JP5759892B2 - Basecoat paint composition - Google Patents

Description

  The present invention relates to a base coat coating composition.

In general, undercoats, intermediate coats, and topcoats are sequentially applied to an object to be coated such as an automobile outer plate part to form a multi-layer coat consisting of an undercoat, an intermediate coat, and an overcoat. The Usually, the undercoat coating film is required to have anticorrosion properties, and the intermediate coating film is required to have smoothness, chipping resistance, ensuring adhesion between the undercoat film and the topcoat film, and the like. Further, the top coat film is required to have an excellent appearance.
Further, the top coating film is generally formed by a multilayer coating film comprising a base coat film and a clear coat film. The base coat film is usually formed by using a colored base coat paint containing pigments such as a luster pigment and a color pigment, and a transparent clear coat film is provided on the base coat film to form a multilayer coat film. By doing so, it is possible to obtain a top coat film having an excellent appearance and having a design property derived from the base coat film and a gloss and smoothness derived from the clear coat film.
In recent years, from the viewpoint of improving the overall coating performance of a multi-layer coating composed of an undercoat, an intermediate coat, a base coat, and a clear coat, the base coat is not only designed but also smooth. It is also desired that the coating film performance such as chipping resistance and adhesion is excellent. Therefore, recently, it has been demanded to develop a base coat paint capable of forming a coating film having excellent design properties, smoothness, adhesion and chipping resistance.
For example, JP-A No. 2002-121472 discloses that 60 mol% or more of the polybasic acid component obtained by reacting a polyhydric alcohol and a polybasic acid is an alicyclic polybasic acid and a hydroxyl group. It is described that a coating film excellent in chipping resistance and appearance can be formed by using, as a base coat paint, a resin composition for a colored paint containing a polyester resin (A) and a curing agent (B). Has been. However, the coating film formed with the colored paint resin composition may still have insufficient smoothness, adhesion and chipping resistance.
JP-A-9-176559 discloses (A) a hydroxyl group- and carboxyl group-containing acrylic resin, (B) a melamine resin, (C) a compound containing one alicyclic epoxy group in one molecule, and (D) It is described that a coating film excellent in chipping resistance and water resistance can be formed by using an aqueous base coat coating composition containing a neutralizing agent. However, even in the coating film obtained by the aqueous base coat coating composition, smoothness, adhesion and chipping resistance may still be insufficient.
Further, JP-A-58-71968 discloses a chipping resistant coating composition containing (A) an aqueous resin, (B) a fine resin powder, (C) a chipping resistant pigment, and (D) a rust preventive pigment. Is described. However, when the chipping-resistant coating composition is used as a base coat paint, the base coat film visually recognized through the clear coat film is inferior in smoothness and sharpness, and a satisfactory appearance as a top coat film is obtained. I can't. The formed base coat film usually has a relatively thin cured film thickness of less than 20 μm, but is obtained when the above chipping-resistant coating composition is applied so as to have such a relatively thin cured film thickness. The base coat film has problems such as inferior smoothness, decreased adhesion between the base coat film and the clear coat film, and decreased adhesion and chipping resistance as the entire multilayer coating film.

An object of the present invention is to provide a base coat coating composition capable of forming a coating film excellent in smoothness, sharpness, adhesion and chipping resistance.
As a result of intensive studies, the present inventors have now obtained a base coat coating composition containing a talc having a specific particle size and a resin containing a hydroxyl group and a phosphate group in addition to the film-forming resin component. The inventors have found that the object can be achieved and have completed the present invention.
Thus, the present invention
(A) a film-forming resin component,
(B) In the volume-based particle size distribution, the particle size (D ₅₀ ) at which the integrated particle size distribution from the small particle size side is 50% is in the range of 1 to 10 μm, and the particle size is 0.1 μm or more and 3 μm. The ratio P _r = P ₂ / P ₁ between the content P ₁ (%) of particles less than 3% and the content P ₂ (%) of particles having a particle size of 3 μm or more and 10 μm or less, and at least 1.1, and (C) The present invention provides a base coat coating composition comprising a resin containing a hydroxyl group and a phosphate group.
If the base coat coating composition of the present invention is used, a multilayer coating film excellent in smoothness, sharpness, adhesion and chipping resistance can be formed on an object to be coated.

［式中、Ｒ^１は水素原子又はメチル基を示し、Ｘは−Ｏ−又は−ＮＨ−を示し、Ｒ^２は炭素数１〜３０の２価の有機基を示す］
で表されるリン酸基含有重合性不飽和モノマーを挙げることができる。
上記一般式（１）において、Ｘは−Ｏ−であることが好ましい。また、Ｒ^２で示される炭素数１〜３０の有機基としては、エーテル結合、エステル結合又はカーボネート結合を有していてもよい炭素数１〜３０のアルキレン基であることが好ましい。
リン酸基含有重合性不飽和モノマー（ｃ−２）としては、例えば、以下に記載するアルキレン変性リン酸基含有重合性不飽和モノマー（ｃ−２−１）、オキシアルキレン変性リン酸基含有重合性不飽和モノマー（ｃ−２−２）、ポリエステル変性リン酸基含有重合性不飽和モノマー（ｃ−２−３）、ポリカーボネート変性リン酸基含有重合性不飽和モノマー（ｃ−２−４）等を用いることが好ましい。これらはそれぞれ単独でもしくは２種以上組み合わせて使用することができる。
アルキレン変性リン酸基含有重合性不飽和モノマー（ｃ−２−１）は下記一般式（２）

［式中、Ｒ^１は前記と同じ意味を有し、Ｒ^３は炭素数１〜６のアルキレン基を示す］
で表されるモノマーである。
上記式（２）において、Ｒ３で示されるアルキレン基は直鎖状又は分岐状のいずれであってもよい。また。該アルキレン基は炭素数２〜４であることが好ましく、炭素数２又は３であることがより好ましい。
上記アルキレン変性リン酸基含有重合性不飽和モノマー（ｃ−２−１）としては、具体的には、例えば、アシッドホスホオキシエチル（メタ）アクリレート、アシッドホスホオキシプロピル（メタ）アクリレート、アシッドホスホオキシブチル（メタ）アクリレート、アシッドホスホオキシヘキシル（メタ）アクリレート等が挙げられる。これらはそれぞれ単独でもしくは２種以上組み合わせて使用することができる。これらのうち、特に、アシッドホスホオキシエチル（メタ）アクリレートが好ましい。
オキシアルキレン変性リン酸基含有重合性不飽和モノマー（ｃ−２−２）は下記一般式（３）

［式中、Ｒ^１は前記と同じ意味を有し、Ｒ^４は炭素数１〜１０のアルキレン基を示し、ｐは３〜３０の整数を示し、複数個のＲ^４は互いに同一でも異なっていてもよい］
で表されるモノマーである。
上記式（３）において、Ｒ４で示されるアルキレン基は直鎖状又は分岐状のいずれであってもよい。また。該アルキレン基は炭素数２〜４であることが好ましく、炭素数２又は３であることがより好ましい。ｐは４〜２０の整数であることが好ましく、５〜１５の整数であることがより好ましい。
オキシアルキレン変性リン酸基含有重合性不飽和モノマー（ｃ−２−２）としては、具体的には、例えば、アシッドホスホオキシテトラ（オキシエチレン）グリコールモノ（メタ）アクリレート、アシッドホスホオキシペンタ（オキシエチレン）グリコールモノ（メタ）アクリレート、アシッドホスホオキシペンタ（オキシプロピレン）グリコールモノ（メタ）アクリレート、アシッドホスホオキシヘキサ（オキシプロピレン）グリコールモノ（メタ）アクリレート等が挙げられる。これらはそれぞれ単独でもしくは２種以上組み合わせて使用することができる。
オキシアルキレン変性リン酸基含有重合性不飽和モノマー（ｃ−２−２）は、例えば、（メタ）アクリル酸を、常法に従いアルキレンオキサイドで変性し、五酸化リン、オキシ塩化リン等の既知のリン酸化剤を作用させた後、加水分解することにより容易に合成することができる。変性に用いるアルキレンオキサイドとしては、例えば、エチレンオキサイド、プロピレンオキサイド、ブチレンオキサイド等を挙げることができる。これらのうち、エチレンオキサイド及び／又はプロピレンオキサイドが好ましく、プロピレンオキサイドがより好ましい。
ポリエステル変性リン酸基含有重合性不飽和モノマー（ｃ−２−３）は下記一般式（４）

［式中、Ｒ^１及びＸは前記と同じ意味を有し、Ｒ^５は炭素数１〜６のアルキレン基を示し、Ｒ^６及びＲ^７は互いに独立して炭素数１〜１０のアルキレン基を示し、ｑは１〜３０の整数を示し、ｑが２以上のとき、複数個のＲ^６は互いに同一でも異なっていてもよく、ｒは０〜３０の整数を示し、ｒが２以上のとき、複数個のＲ^７は互いに同一でも異なっていてもよい］
で表されるモノマーである。
上記式（４）において、Ｒ５で示されるアルキレン基は直鎖状又は分岐状のいずれであってもよい。また、該アルキレン基は炭素数２〜４であることが好ましく、炭素数２又は３であることがより好ましい。Ｒ６で示されるアルキレン基は直鎖状又は分岐状のいずれであってもよい。また、該アルキレン基は炭素数２〜６であることが好ましく、炭素数４〜６であることがより好ましい。Ｒ７で示されるアルキレン基は直鎖状又は分岐状のいずれであってもよい。また。該アルキレン基は炭素数２〜４であることが好ましく、炭素数２又は３であることがより好ましい。ｑは１〜２０の整数であることが好ましく、１〜１０の整数であることがより好ましい。ｒは０〜２０の整数であることが好ましく、０〜１０の整数であることがより好ましい。
ポリエステル変性リン酸基含有重合性不飽和モノマー（ｃ−２−３）は、例えば、水酸基含有（メタ）アクリレート類を、常法に従い、環状エステル及び／又はアルキレンオキサイドで変性し、リン酸化剤を作用させた後、加水分解することにより容易に合成することができる。
上記環状エステルとしては、例えば、β−プロピオラクトン、γ−ブチロラクトン、δ−バレロラクトン、ε−カプロラクトン等の炭素数３〜１１のラクトン類を挙げることができる。これらはそれぞれ単独でもしくは２種以上組み合わせて使用することができる。これらのうち、ε−カプロラクトンを用いることが好ましい。また、上記リン酸化剤としては、それ自体既知のもの、例えば、五酸化リン、オキシ塩化リン等を使用することができる。
ポリカーボネート変性リン酸基含有重合性不飽和モノマー（ｃ−２−４）は下記一般式（５）

［式中、Ｒ^１及びＸは前記と同じ意味を有し、Ｒ^８は炭素数１〜６のアルキレン基を示し、Ｒ^９及びＲ^１０は互いに独立して炭素数１〜１０のアルキレン基を示し、ｓは１〜３０の整数を示し、ｓが２以上のとき、複数個のＲ^９は互いに同一でも異なっていてもよく、ｔは０〜３０の整数を示し、ｔが２以上のとき、複数個のＲ^１０は互いに同一でも異なっていてもよい］
で表されるモノマーである。
上記式（５）において、Ｒ^８で示されるアルキレン基は直鎖状又は分岐状のいずれであってもよい。また、該アルキレン基は炭素数２〜４であることが好ましく、炭素数２又は３であることがより好ましい。Ｒ^９で示されるアルキレン基は直鎖状又は分岐状のいずれであってもよい。また、該アルキレン基は炭素数２〜６であることが好ましく、炭素数２〜４であることがより好ましい。Ｒ^１０で示されるアルキレン基は直鎖状又は分岐状のいずれであってもよい。また、該アルキレン基は炭素数２〜４であることが好ましく、炭素数２又は３であることがより好ましい。ｓは１〜２０の整数であるのが好ましく、１〜１０の整数であるのがより好ましい。ｔは０〜２０の整数であるのが好ましく、０〜１０の整数であることがより好ましい。
ポリカーボネート変性リン酸基含有重合性不飽和モノマー（ｃ−２−４）は、例えば、水酸基含有（メタ）アクリレート類を、常法に従い、環状カーボネート及び／又はアルキレンオキサイドで変性し、リン酸化剤を作用させた後、加水分解することにより容易に合成することができる。
上記環状カーボネートとしては、例えば、１，３−ジオキソラン−２−オン、１，３−ジオキサン−２−オン、１，３−ジオキセパン−２−オン等が挙げられる。これらはそれぞれ単独でもしくは２種以上組み合わせて使用することができる。また、リン酸化剤としては、それ自体既知のもの、例えば、五酸化リン、オキシ塩化リン等を使用することができる。
その他の重合性不飽和モノマー（ｃ−３）
その他の重合性不飽和モノマー（ｃ−３）は、水酸基含有重合性不飽和モノマー（ｃ−１）及びリン酸基含有重合性不飽和モノマー（ｃ−２）と共重合し得る、当該モノマー（ｃ−１）及び（ｃ−２）以外の重合性不飽和モノマーである。該モノマー（ｃ−３）は、水酸基及びリン酸基を含有する樹脂（Ｃ）に望まれる特性に応じて適宜選択して使用することができる。該モノマー（ｃ−３）の具体例としては以下の（ｉ）〜（ｘｖｉｉｉ）に記載するものを挙げることができる。これらはそれぞれ単独でもしくは２種以上組み合わせて使用することができる。
（ｉ） アルキル又はシクロアルキル（メタ）アクリレート：例えば、メチル（メタ）アクリレート、エチル（メタ）アクリレート、ｎ−プロピル（メタ）アクリレート、ｉ−プロピル（メタ）アクリレート、ｎ−ブチル（メタ）アクリレート、ｉ−ブチル（メタ）アクリレート、ｔｅｒｔ−ブチル（メタ）アクリレート、ｎ−ヘキシル（メタ）アクリレート、ｎ−オクチル（メタ）アクリレート、２−エチルヘキシル（メタ）アクリレート、ノニル（メタ）アクリレート、トリデシル（メタ）アクリレート、ラウリル（メタ）アクリレート、ステアリル（メタ）アクリレート、イソステアリル（メタ）アクリレート、シクロヘキシル（メタ）アクリレート、メチルシクロヘキシル（メタ）アクリレート、ｔ−ブチルシクロヘキシル（メタ）アクリレート、シクロドデシル（メタ）アクリレート、トリシクロデカニル（メタ）アクリレート等。
（ｉｉ） イソボルニル基を有する重合性不飽和モノマー：例えば、イソボルニル（メタ）アクリレート等。
（ｉｉｉ） アダマンチル基を有する重合性不飽和モノマー：例えば、アダマンチル（メタ）アクリレート等。
（ｉｖ） トリシクロデセニル基を有する重合性不飽和モノマー：例えば、トリシクロデセニル（メタ）アクリレート等。
（ｖ） 芳香環含有重合性不飽和モノマー：例えば、ベンジル（メタ）アクリレート、スチレン、α−メチルスチレン、ビニルトルエン等。
（ｖｉ） アルコキシシリル基を有する重合性不飽和モノマー：例えば、ビニルトリメトキシシラン、ビニルトリエトキシシラン、ビニルトリス（２−メトキシエトキシ）シラン、γ−（メタ）アクリロイルオキシプロピルトリメトキシシラン、γ−（メタ）アクリロイルオキシプロピルトリエトキシシラン等。
（ｖｉｉ） フッ素化アルキル基を有する重合性不飽和モノマー：例えば、パーフルオロブチルエチル（メタ）アクリレート、パーフルオロオクチルエチル（メタ）アクリレート等のパーフルオロアルキル（メタ）アクリレート；フルオロオレフィン等。
（ｖｉｉｉ） マレイミド基等の光重合性官能基を有する重合性不飽和モノマー。
（ｉｘ） ビニル化合物：例えば、Ｎ−ビニルピロリドン、エチレン、ブタジエン、クロロプレン、プロピオン酸ビニル、酢酸ビニル等。
（ｘ） カルボキシル基含有重合性不飽和モノマー：例えば、（メタ）アクリル酸、マレイン酸、クロトン酸、β−カルボキシエチルアクリレート等。
（ｘｉ） 含窒素重合性不飽和モノマー：例えば、（メタ）アクリロニトリル、（メタ）アクリルアミド、Ｎ，Ｎ−ジメチルアミノエチル（メタ）アクリレート、Ｎ，Ｎ−ジエチルアミノエチル（メタ）アクリレート、Ｎ，Ｎ−ジメチルアミノプロピル（メタ）アクリルアミド、メチレンビス（メタ）アクリルアミド、エチレンビス（メタ）アクリルアミド、２−（メタクリロイルオキシ）エチルトリメチルアンモニウムクロライド、グリシジル（メタ）アクリレートとアミン類との付加物等。
（ｘｉｉ） 重合性不飽和基を１分子中に２個以上有する重合性不飽和モノマー：例えば、アリル（メタ）アクリレート、１，６−ヘキサンジオールジ（メタ）アクリレート等。
（ｘｉｉｉ） エポキシ基含有重合性不飽和モノマー：例えば、グリシジル（メタ）アクリレート、β−メチルグリシジル（メタ）アクリレート、３，４−エポキシシクロヘキシルメチル（メタ）アクリレート、３，４−エポキシシクロヘキシルエチル（メタ）アクリレート、３，４−エポキシシクロヘキシルプロピル（メタ）アクリレート、アリルグリシジルエーテル等。
（ｘｉｖ） 分子末端がアルコキシ基であるポリオキシエチレン鎖を有する（メタ）アクリレート。
（ｘｖ） スルホン酸基を有する重合性不飽和モノマー：例えば、２−アクリルアミド−２−メチルプロパンスルホン酸、２−スルホエチル（メタ）アクリレート、アリルスルホン酸、４−スチレンスルホン酸等；これらスルホン酸のナトリウム塩、アンモニウム塩等。
（ｘｖｉ） 紫外線吸収性官能基を有する重合性不飽和モノマー：例えば、２−ヒドロキシ−４−（３−メタクリロイルオキシ−２−ヒドロキシプロポキシ）ベンゾフェノン、２−ヒドロキシ−４−（３−アクリロイルオキシ−２−ヒドロキシプロポキシ）ベンゾフェノン、２，２’−ジヒドロキシ−４−（３−メタクリロイルオキシ−２−ヒドロキシプロポキシ）ベンゾフェノン、２，２’−ジヒドロキシ−４−（３−アクリロイルオキシ−２−ヒドロキシプロポキシ）ベンゾフェノン、２−（２’−ヒドロキシ−５’−メタクリロイルオキシエチルフェニル）−２Ｈ−ベンゾトリアゾール等。
（ｘｖｉｉ） 光安定性重合性不飽和モノマー：例えば、４−（メタ）アクリロイルオキシ−１，２，２，６，６−ペンタメチルピペリジン、４−（メタ）アクリロイルオキシ−２，２，６，６−テトラメチルピペリジン、４−シアノ−４−（メタ）アクリロイルアミノ−２，２，６，６−テトラメチルピペリジン、１−（メタ）アクリロイル−４−（メタ）アクリロイルアミノ−２，２，６，６−テトラメチルピペリジン、１−（メタ）アクリロイル−４−シアノ−４−（メタ）アクリロイルアミノ−２，２，６，６−テトラメチルピペリジン、４−クロトノイルオキシ−２，２，６，６−テトラメチルピペリジン、４−クロトノイルアミノ−２，２，６，６−テトラメチルピペリジン、１−クロトノイル−４−クロトノイルオキシ−２，２，６，６−テトラメチルピペリジン等。
（ｘｖｉｉｉ） カルボニル基を有する重合性不飽和モノマー：例えば、アクロレイン、ダイアセトンアクリルアミド、ダイアセトンメタクリルアミド、アセトアセトキシエチルメタクリレート、ホルミルスチロール、４〜７個の炭素原子を有するビニルアルキルケトン（例えば、ビニルメチルケトン、ビニルエチルケトン、ビニルブチルケトン）等。
得られる塗膜の耐水性の観点から、その他の重合性不飽和モノマー（ｃ−３）としては、その成分の少なくとも一部として、疎水性重合性不飽和モノマーを含有することが好ましい。
上記疎水性重合性不飽和モノマーには、炭素数６以上の直鎖状、分岐状又は環状の飽和又は不飽和炭化水素基を有する重合性不飽和モノマーが包含され、水酸基含有重合性不飽和モノマー等の親水性基を有するモノマーは除外される。そのような疎水性重合性不飽和モノマーとしては、例えば、ｎ−ヘキシル（メタ）アクリレート、オクチル（メタ）アクリレート、２−エチルヘキシル（メタ）アクリレート、ノニル（メタ）アクリレート、トリデシル（メタ）アクリレート、ラウリル（メタ）アクリレート、ステアリル（メタ）アクリレート、イソステアリル（メタ）アクリレート、シクロヘキシル（メタ）アクリレート、メチルシクロヘキシル（メタ）アクリレート、ｔ−ブチルシクロヘキシル（メタ）アクリレート、シクロドデシル（メタ）アクリレート等のアルキル又はシクロアルキル（メタ）アクリレート；イソボルニル（メタ）アクリレート等のイソボルニル基を有する重合性不飽和モノマー；アダマンチル（メタ）アクリレート等のアダマンチル基を有する重合性不飽和モノマー；ベンジル（メタ）アクリレート、スチレン、α−メチルスチレン、ビニルトルエン等の芳香環含有重合性不飽和モノマー等を挙げることができる。これらはそれぞれ単独でもしくは２種以上組み合わせて使用することができる。得られる塗膜の耐水性向上の観点から、特に、芳香環含有重合性不飽和モノマーを用いることが好ましく、スチレンを用いることがさらに好ましい。
疎水性重合性不飽和モノマーは、水酸基含有重合性不飽和モノマー（ｃ−１）、リン酸基含有重合性不飽和モノマー（ｃ−２）及びその他の重合性不飽和モノマー（ｃ−３）の合計量を基準として、一般に２〜８０質量％、特に１０〜６０質量％、さらに特に１５〜４０質量％の範囲内で使用することが好適である。
共重合体（Ｃ’）において、水酸基含有重合性不飽和モノマー（ｃ−１）、リン酸基含有重合性不飽和モノマー（ｃ−２）及びその他の重合性不飽和モノマー（ｃ−３）の使用割合は、モノマー（ｃ−１）〜（ｃ−３）の合計量を基準にして下記の範囲内とすることができる。
水酸基含有重合性不飽和モノマー（ｃ−１）：１〜５０質量％、好まし
くは５〜４０質量％、さ
らに好ましくは１０〜
３０質量％、
リン酸基含有重合性不飽和モノマー（ｃ−２）：１〜７０質量％、好ま
しくは１０〜５５質
量％、さらに好ましく
は２０〜４５質量％、
その他の重合性不飽和モノマー（ｃ−３）：０〜９８質量％、好ましく
は５〜８５質量％、さらに
好ましくは２５〜７０質
量％。
水酸基含有重合性不飽和モノマー（ｃ−１）、リン酸基含有重合性不飽和モノマー（ｃ−２）及びその他の重合性不飽和モノマー（ｃ−３）の共重合は、例えば、有機溶剤中での溶液重合法、水性媒体中でのエマルション重合法等のそれ自体既知の方法により行なうことができる。これらのうち、溶液重合法が好適である。
溶液重合法による場合は、例えば、水酸基含有重合性不飽和モノマー（ｃ−１）、リン酸基含有重合性不飽和モノマー（ｃ−２）及びその他の重合性不飽和モノマー（ｃ−３）と、ラジカル重合開始剤との混合物を有機溶媒に溶解又は分散せしめ、通常、約８０〜約２００℃の温度で１〜１０時間程度撹拌しながら加熱して共重合させることにより共重合体（Ｃ’）を得ることができる。
上記共重合反応において使用し得る有機溶媒としては、例えば、ヘプタン、トルエン、キシレン、オクタン、ミネラルスピリット等の炭化水素系溶剤；酢酸エチル、酢酸ｎ一ブチル、酢酸イソブチル、エチレングリコールモノメチルエーテルアセテート、ジエチレングリコールモノブチルエーテルアセテート等のエステル系溶剤；メチルエチルケトン、メチルイソブチルケトン、ジイソブチルケトン、シクロヘキサノン等のケトン系溶剤；メタノール、エタノール、イソプロパノール、ｎ−ブタノール、ｓｅｃ−ブタノール、イソブタノール等のアルコール系溶剤；ｎ−ブチルエーテル、ジオキサン、エチレングリコールモノメチルエーテル、エチレングリコールモノブチルエーテル、プロピレングリコールモノメチルエーテル、プロピレングリコールモノプロピルエーテル、プロピレングリコールモノブチルエーテル、ジプロピレングリコールモノメチルエーテル、ジプロピレングリコールモノブチルエーテル、トリプロピレングリコールモノメチルエーテル等のエーテル系溶剤；Ｎ，Ｎ−ジメチルアセトアミド、Ｎ，Ｎ−ジメチルホルムアミド、Ｎ−メチル−２−ピロリドン、Ｎ，Ｎ−ジメチル−β−メトキシプロピオンアミド等のアミド系溶剤；１，３−ジメチル−２−イミダゾーリジノン等のウレア系溶剤；ジメチルスルホキシド等のスルホキシド系溶剤；テトラメチレンスルホン等のスルホン系溶剤；丸善石油化学（株）製の「スワゾール３１０」、「スワゾール１０００」、「スワゾール１５００」（以上、いずれも商品名）等の芳香族石油系溶剤等を挙げることができる。これらの有機溶剤はそれぞれ単独でもしくは２種以上組み合わせて使用することができる。溶液重合における有機溶剤の使用量は、モノマー（ｃ−１）〜（ｃ−３）の合計量１００質量部あたり、通常４００質量部以下であることが好ましい。
前記ラジカル重合開始剤としては、例えば、シクロヘキサノンパーオキサイド、３，３，５−トリメチルシクロヘキサノンパーオキサイド、メチルシクロヘキサノンパーオキサイド等のケトンパーオキサイド類；１，１−ビス（ｔｅｒｔ−ブチルパーオキシ）−３，３，５−トリメチルシクロヘキサン、１，１−ビス（ｔｅｒｔ−ブチルパーオキシ）シクロヘキサン、ｎ−ブチル−４，４−ビス（ｔｅｒｔ−ブチルパーオキシ）バレレート等のパーオキシケタール類；クメンハイドロパーオキサイド、２，５−ジメチルヘキサン−２，５−ジハイドロパーオキサイド等のハイドロパーオキサイド類；１，３−ビス（ｔｅｒｔ−ブチルパーオキシ−ｍ−イソプロピル）ベンゼン、２，５−ジメチル−２，５−ジ（ｔｅｒｔ−ブチルパーオキシ）ヘキサン、ジイソプロピルベンゼンパーオキサイド、ｔｅｒｔ−ブチルクミルパーオキサイド等のジアルキルパーオキサイド類；デカノイルパーオキサイド、ラウロイルパーオキサイド、ベンゾイルパーオキサイド、２，４−ジクロロベンゾイルパーオキサイド等のジアシルパーオキサイド類；ビス（ｔｅｒｔ−ブチルシクロヘキシル）パーオキシジカーボネート等のパーオキシカーボネート類；ｔｅｒｔ−ブチルパーオキシベンゾエート、２，５−ジメチル−２，５−ジ（ベンゾイルパーオキシ）ヘキサン等のパーオキシエステル類等の有機過酸化物系重合開始剤；２，２’−アゾビスイソブチロニトリル、１，１−アゾビス（シクロヘキサン−１−カルボニトリル）、アゾクメン２，２’−アゾビスメチルバレロニトリル、４，４’−アゾビス（４−シアノ吉草酸）等のアゾ系重合開始剤等を挙げることができる。これらのラジカル重合開始剤の使用量は、特に限定されるものではないが、モノマー（ｃ−１）〜（ｃ−３）の合計量１００質量部あたり、通常約０．１〜約１５質量部の範囲内が好ましく、約０．３〜約１０質量部の範囲内がより好ましい。
上記重合反応において、モノマー成分及び重合開始剤の添加順序は、特に制約されないが、重合反応における温度制御の容易性、不良な架橋ゲル化物の生成抑制等の点から、重合開始剤は重合初期に一括仕込みするよりも重合初期から重合後期にわたって数回に分けて分割滴下する方が好ましい。
かくして得られる共重合体（Ｃ’）は一般に１５〜２００ｍｇＫＯＨ／ｇ、特に２０〜１４０ｍｇＫＯＨ／ｇ、さらに特に３０〜１００ｍｇＫＯＨ／ｇの範囲内の水酸基価を有することが好適である。また、該共重合体（Ｃ’）は一般に１０〜２００ｍｇＫＯＨ／ｇ、特に４０〜１７０ｍｇＫＯＨ／ｇ、さらに特に６０〜１５０ｍｇＫＯＨ／ｇの範囲内の酸価を有することが好適である。さらに、該共重合体（Ｃ’）は一般に２，０００〜１００，０００、特に４，０００〜５０，０００、さらに特に８，０００〜３０，０００の範囲内の数平均分子量を有することが好適である。
ベースコート塗料組成物
本発明のベースコート塗料組成物は、以上に述べた被膜形成性樹脂成分（Ａ）、タルク（Ｂ）ならびに水酸基及びリン酸基を含有する樹脂（Ｃ）を、通常の塗料化手段により、溶媒中に均一に混合することにより調製することができる。上記溶媒としては、有機溶剤又は水性溶媒を使用することができる。水性溶媒としては、脱イオン水又は脱イオン水と親水性有機溶媒との混合物を使用することができる。該親水性有機溶媒としては、例えば、プロピレングリコールモノメチルエーテル等を挙げることができる。
上記混合の際、得られる塗膜の平滑性、鮮映性、付着性、耐チッピング性等の観点から、タルク（Ｂ）と水酸基及びリン酸基を含有する樹脂（Ｃ）とをあらかじめ混合して顔料分散液を調製しておき、その顔料分散液を被膜形成性樹脂成分（Ａ）等と共に有機溶剤中又は水性媒体中で混合、分散せしめることが好ましい。
本発明のベースコート塗料組成物における被膜形成性樹脂成分（Ａ）、タルク（Ｂ）ならびに水酸基及びリン酸基を含有する樹脂（Ｃ）の含有量は、被膜形成性樹脂成分（Ａ）ならびに水酸基及びリン酸基を含有する樹脂（Ｃ）の合計樹脂固形分１００質量部を基準として、次の範囲内にあることが好適である。
被膜形成性樹脂成分（Ａ）：５０〜９９．５質量部、好ましくは７５〜
９９質量部、さらに好ましくは８５〜９８
質量部、
タルク（Ｂ）：２〜５０質量部、好ましくは５〜３０質量部、さらに好
ましくは６．５〜２５質量部、さらに特に好ましくは８
〜２０質量部、
水酸基及びリン酸基を含有する樹脂（Ｃ）：０．５〜５０質量部、好ま
しくは１〜２５質量部、さ
らに好ましくは２〜１５
質量部。
本発明のベースコート塗料組成物を使用することにより、付着性及び耐チッピング性に優れ、かつ上塗り塗料に求められる優れた平滑性及び鮮映性を有する塗膜を形成せしめることができる。その理由としては、本塗料中のタルク（Ｂ）が、小粒径側からの積算粒径分布が５０％となる粒径（Ｄ_５０）が１〜１０μｍの範囲内であり、比較的小粒径のタルクを主成分とする一方で、粒径が０．１μｍ以上３μｍ未満の粒子の含有率Ｐ_１（％）と粒径が３μｍ以上１０μｍ以下の粒子の含有率Ｐ_２（％）との比Ｐ_ｒ＝Ｐ_２／Ｐ_１が１．１以上であり、粒径が０．１μｍ以上３μｍ未満の粒子よりも粒径が３μｍ以上１０μｍ以下の粒子を多く含有し、過度に小粒径化していないため、耐チッピング性を損なわずに、優れた平滑性及び鮮映性を有する塗膜を形成せしめるできることが推察される。さらに、水酸基及びリン酸基を含有する樹脂（Ｃ）中のリン酸基が、タルク（Ｂ）と相互作用し、タルク（Ｂ）を塗膜中に均一に分散させるため、得られる塗膜の平滑性、鮮映性及び塗膜強度が向上し、結果として、平滑性、鮮映性、付着性及び耐チッピング性に優れた塗膜が形成されると推察される。
本発明の塗料組成物は、得られる塗膜の平滑性向上の観点から、さらに、疎水性溶媒（Ｄ）を含有することが好ましい。
疎水性溶媒（Ｄ）としては、２０℃における１００ｇの水に対する溶解質量が１０ｇ以下、好ましくは５ｇ以下、より好ましくは１ｇ以下の有機溶媒を用いることが望ましい。かかる有機溶媒としては、例えば、ゴム揮発油、ミネラルスピリット、トルエン、キシレン、ソルベントナフサ等の炭化水素系溶媒；１−ヘキサノール、１−オクタノール、２−オクタノール、２−エチル−１−ヘキサノール、１−デカノール、ベンジルアルコール、エチレングリコールモノ２−エチルヘキシルエーテル、プロピレングリコールモノｎ−ブチルエーテル、ジプロピレングリコールモノｎ−ブチルエーテル、トリプロピレングリコールモノｎ−ブチルエーテル、プロピレングリコールモノ２−エチルヘキシルエーテル、プロピレングリコールモノフェニルエーテル等のアルコール系溶媒；酢酸ｎ−ブチル、酢酸イソブチル、酢酸イソアミル、酢酸メチルアミル、酢酸エチレングリコールモノブチルエーテル等のエステル系溶媒；メチルイソブチルケトン、シクロヘキサノン、エチルｎ−アミルケトン、ジイソブチルケトン等のケトン系溶媒を挙げることができる。これらはそれぞれ単独でもしくは２種以上組み合わせて使用することができる。
疎水性溶媒（Ｄ）としては、得られる塗膜の平滑性の観点から、アルコール系疎水性溶媒を用いることが好ましい。なかでも、炭素数７〜１４のアルコール系疎水性溶媒が好ましく、１−オクタノール、２−オクタノール、２−エチル−１−ヘキサノール、エチレングリコールモノ２−エチルヘキシルエーテル、プロピレングリコールモノｎ−ブチルエーテル、ジプロピレングリコールモノｎ−ブチルエーテルからなる群より選ばれる少なくとも１種のアルコール系疎水性溶媒がさらに好ましい。
本発明の塗料組成物が疎水性溶媒（Ｄ）を含有する場合、疎水性溶媒（Ｄ）の含有量は、被膜形成性樹脂成分（Ａ）ならびに水酸基及びリン酸基を含有する樹脂（Ｃ）の合計樹脂固形分１００質量部あたり、通常１０〜１００質量部、特に２０〜８０質量部、さらに特に３０〜６０質量部の範囲内であることが好適である。
また、本発明の塗料組成物は、光輝性顔料（Ｅ）を含有することができる。光輝性顔料（Ｅ）は、塗膜にキラキラとした光輝感や光干渉性模様を付与するために使用される顔料であり、具体的には、例えば、ノンリーフィング型もしくはリーフィング型アルミニウム（蒸着アルミニウムも含む）、銅、亜鉛、真ちゅう、ニッケル、ガラスフレーク、酸化アルミニウム、雲母、酸化チタンや酸化鉄で被覆された酸化アルミニウム、酸化チタンや酸化鉄で被覆された雲母等から選ばれる少なくとも１種の顔料を使用することができる。なかでも、特に、アルミニウム顔料を使用することが好適である。
上記メタリック顔料はりん片状であることが好ましく、これらのメタリック顔料としては、長手方向寸法が１〜１００μｍ、特に５〜４０μｍの範囲内、そして厚さが０．００１〜５μｍ、特に０．０１〜２μｍの範囲内にあるものが適している。
光輝性顔料（Ｅ）は、被膜形成性樹脂成分（Ａ）ならびに水酸基及びリン酸基を含有する樹脂（Ｃ）の合計樹脂固形分１００質量部あたり、通常１〜５０質量部、特に５〜３５質量部、さらに特に８〜２０質量部の範囲内で使用することが好適である。
本発明の塗料組成物は、さらに必要に応じて、着色顔料、体質顔料、増粘剤、硬化触媒、紫外線吸収剤、光安定剤、消泡剤、可塑剤、有機溶剤、表面調整剤、沈降防止剤等の通常の塗料用添加剤をそれぞれ単独でもしくは２種以上組み合わせて含有することができる。
上記着色顔料としては、例えば、酸化チタン、亜鉛華、カーボンブラック、モリブデンレッド、プルシアンブルー、コバルトブルー、アゾ系顔料、フタロシアニン系顔料、キナクリドン系顔料、イソインドリン系顔料、スレン系顔料、ペリレン系顔料、ジオキサジン系顔料、ジケトピロロピロール系顔料等が挙げられ、上記体質顔料としては、例えば、クレー、カオリン、バリタ、硫酸バリウム、炭酸バリウム、炭酸カルシウム、シリカ、アルミナホワイト等が挙げられる。
本発明の塗料組成物は、通常、光輝性顔料（Ｅ）及び／又は着色顔料を含有する着色ベースコート塗料組成物として使用することができる。
増粘剤としては、例えば、ケイ酸塩、金属ケイ酸塩、モンモリロナイト、コロイド状アルミナ等の無機系増粘剤；（メタ）アクリル酸と（メタ）アクリル酸エステルとの共重合体、ポリアクリル酸ソーダ等のポリアクリル酸系増粘剤；１分子中に親水性部分と疎水性部分を有し、水性媒体中において、該疎水性部分が塗料中の顔料やエマルション粒子の表面に吸着したり、該疎水性部分同士が会合したりすることにより効果的に増粘作用を示す会合型増粘剤；カルボキシメチルセルロース、メチルセルロース、ヒドロキシエチルセルロース等の繊維素誘導体系増粘剤；カゼイン、カゼイン酸ソーダ、カゼイン酸アンモニウム等のタンパク質系増粘剤；アルギン酸ソーダ等のアルギン酸系増粘剤；ポリビニルアルコール、ポリビニルピロリドン、ポリビニルベンジルエーテル共重合体等のポリビニル系増粘剤；プルロニックポリエーテル、ポリエーテルジアルキルエステル、ポリエーテルジアルキルエーテル、ポリエーテルエポキシ変性物等のポリエーテル系増粘剤；ビニルメチルエーテル−無水マレイン酸共重合体の部分エステル等の無水マレイン酸共重合体系増粘剤；ポリアマイドアミン塩等のポリアマイド系増粘剤等が挙げられる。これらの増粘剤はそれぞれ単独で又は２種以上組み合わせて使用することができる。上記増粘剤としては、特にポリアクリル酸系増粘剤及び／又は会合型増粘剤が好適である。ポリアクリル酸系増粘剤としては、市販品を使用することができ、例えば、ロームアンドハース社製の「プライマルＡＳＥ−６０」、「プライマルＴＴ−６１５」、「プライマルＲＭ−５」（以上、いずれも商品名）；サンノプコ社製の「ＳＮシックナー６１３」、「ＳＮシックナー６１８」、「ＳＮシックナー６３０」、「ＳＮシックナー６３４」、「ＳＮシックナー６３６」（以上、いずれも商品名）等の市販品が挙げられる。また、上記会合型増粘剤としては、市販品を使用することができ、例えば、ＡＤＥＫＡ社製の「ＵＨ−４２０」、「ＵＨ−４５０」、「ＵＨ−４６２」、「ＵＨ−４７２」、「ＵＨ−５４０」、「ＵＨ−７５２」、「ＵＨ−７５６ＶＦ」、「ＵＨ−８１４Ｎ」（以上、いずれも商品名）；ロームアンドハース社製の「プライマルＲＭ−８Ｗ」、「プライマルＲＭ−８２５」、「プライマルＲＭ−２０２０ＮＰＲ」、「プライマルＲＭ−１２Ｗ」、「プライマルＳＣＴ−２７５」（以上、いずれも商品名）；サンノプコ社製の「ＳＮシックナー６１２」、「ＳＮシックナー６２１Ｎ」、「ＳＮシックナー６２５Ｎ」、「ＳＮシックナー６２７Ｎ」、「ＳＮシックナー６６０Ｔ」（以上、いずれも商品名）等の市販品が挙げられる。
本発明の塗料組成物が上記増粘剤を含有する場合、該増粘剤の含有量は、被膜形成性樹脂成分（Ａ）ならびに水酸基及びリン酸基を含有する樹脂（Ｃ）の合計樹脂固形分１００質量部あたり、通常０．０１〜１０質量部、特に０．０５〜３質量部、さらに好ましくは０．１〜２質量部の範囲内であることが好適である。
本発明の塗料組成物は、一般に５〜５０質量％、特に１５〜４０質量％、さらに特に２０〜３０質量％の範囲内の固形分を有することが好適である。
塗装
本発明の塗料組成物は、種々の被塗物に塗装することにより、優れた平滑性、鮮映性、付着性及び耐チッピング性を有する塗膜を形成せしめることができる。
本発明の塗料組成物を適用し得る被塗物としては、特に限定されるものではなく、例えば、乗用車、トラック、オートバイ、バス等の自動車車体の外板部；自動車部品；携帯電話、オーディオ機器等の家庭用電気電子製品の外板部等を挙げることができる。なかでも、自動車車体の外板部及び自動車部品が好ましい。
また、本発明の塗料組成物を適用し得る被塗物の材質もまた、特に限定されるものではなく、例えば、鉄、アルミニウム、真鍮、銅板、ステンレス鋼板、ブリキ板、亜鉛メッキ鋼板、合金化亜鉛（Ｚｎ−Ａｌ、Ｚｎ−Ｎｉ、Ｚｎ−Ｆｅ等）メッキ鋼板等の金属材料；ポリエチレン樹脂、ポリプロピレン樹脂、アクリロニトリル−ブタジエン−スチレン（ＡＢＳ）樹脂、ポリアミド樹脂、アクリル樹脂、塩化ビニリデン樹脂、ポリカーボネート樹脂、ポリウレタン樹脂、エポキシ樹脂等の樹脂類や各種のＦＲＰ等のプラスチック材料；ガラス、セメント、コンクリート等の無機材料；木材；繊維材料（紙、布等）等を挙げることができ、なかでも、金属材料及びプラスチック材料が好適である。
上記被塗物は、上記金属材料等の基材上に、電着塗膜等の下塗り塗膜を形成したものであってもよい。また、該基材上に下塗り塗膜及び中塗り塗膜を順に形成したものであってもよい。基材が金属材料である場合は、該基材上に下塗り塗膜を形成させる前に、予めりん酸塩処理、クロメート処理、複合酸化物処理等の表面処理が施されたものであってもよい。
本発明の塗料組成物の塗装方法としては、特に限定されず、例えば、エアスプレー塗装、エアレススプレー塗装、回転霧化塗装、カーテンコート塗装等が挙げられる。これらの塗装方法でウエット塗膜を形成せしめることができる。これらの内、エアスプレー塗装、回転霧化塗装等の方法が好ましい。塗装に際して、必要に応じて、静電印加を行ってもよい。
本発明の塗料組成物の塗布量は、硬化膜厚として、通常２〜４０μｍ、好ましくは５〜３０μｍ、さらに好ましくは８〜１８μｍの範囲内とすることができる。
ウェット塗膜の硬化は、被塗物に本発明の塗料組成物を塗装後、加熱することにより行うことができる。加熱はそれ自体既知の加熱手段により行うことができ、例えば、熱風炉、電気炉、赤外線誘導加熱炉等の乾燥炉を使用することができる。加熱温度は通常約８０〜約１８０℃、好ましくは約１００〜約１７０℃、さらに好ましくは約１２０〜約１６０℃の範囲内であることができる。また、加熱時間は通常約１０〜約９０分間、好ましくは約１５〜約６０分間、さらに好ましくは約２０〜約４０分間の範囲内とすることができる。
本発明の塗料組成物が水性塗料の場合、ワキ等の塗膜欠陥の発生を防止するという観点から、該塗料組成物の塗装後、上記加熱硬化を行なう前に、塗膜が実質的に硬化しない加熱条件でプレヒート、エアブロー等を行うことが好ましい。プレヒートの温度は通常約４０〜約１００℃、好ましくは約５０〜約９０℃、さらに好ましくは約６０〜約８０℃の範囲内であることができる。プレヒートの時間は通常約３０秒間〜約２０分間、好ましくは約１〜約１５分間、さらに好ましくは約２〜約１０分間の範囲内とすることができる。また、上記エアブローは、通常、被塗物の塗装面に、常温の又は約２５℃〜約８０℃の範囲内の温度に加熱された空気を約３０秒間〜約１５分間吹き付けることにより行うことができる。
本発明の塗料組成物によって形成される塗膜上には、必要に応じて、それ自体既知のクリヤーコート塗料組成物を塗装することができる。該クリヤーコート塗料組成物を塗装する場合、本発明の塗料組成物によって形成される塗膜は、未硬化塗膜であってもよく、或いは硬化塗膜であってもよい。本発明の塗料組成物によって形成される塗膜が未硬化塗膜である場合、上記クリヤーコート塗料組成物を塗装後に、本発明の塗料組成物の塗膜とクリヤーコート塗料組成物の塗膜を同時に加熱硬化させることができる。
上記クリヤーコート塗料組成物は、それ自体既知の方法、例えば、エアスプレー塗装、エアレススプレー塗装、回転霧化塗装等の方法によって塗装することができる。該クリヤーコート塗料組成物の塗装膜厚は、硬化膜厚として、一般に１０〜８０μｍ、好ましくは１５〜６０μｍ、さらに好ましくは２０〜５０μｍの範囲内とすることができる。
上記クリヤーコート塗料組成物の硬化は、前述した如きそれ自体既知の加熱手段により行うことができる。加熱温度は通常約８０〜約１８０℃、好ましくは約１００〜約１７０℃、さらに好ましくは約１２０〜約１６０℃の範囲内であることができる。また、加熱時間は通常約１０〜約９０分間、好ましくは約１５〜約６０分間、さらに好ましくは約２０〜約４０分間の範囲内とすることができる。   Hereinafter, the base coat coating composition of the present invention will be described in more detail.
  The base coat paint composition of the present invention (hereinafter sometimes abbreviated as “the present paint” or “the paint composition of the present invention”)
(A) a film-forming resin component,
(B) In the volume-based particle size distribution, the particle size (D₅₀) Is in the range of 1 to 10 μm and the particle content P is 0.1 μm or more and less than 3 μm.₁(%) And the content P of particles having a particle size of 3 μm to 10 μm₂Ratio P to (%)_r= P₂/ P₁A talc having a value of at least 1.1, and
(C) Resin containing hydroxyl group and phosphate group
Is included.
Film-forming resin component (A)
  As the film-forming resin component (A), there can be used a film-forming resin component known per se, which comprises a base resin and optionally further contains a curing agent, which has been conventionally used in the paint field. Examples of the base resin include acrylic resin, polyester resin, alkyd resin, and polyurethane resin, and preferably have a crosslinkable functional group such as a hydroxyl group, a carboxyl group, and an epoxy group.
  Particularly preferred as the film-forming resin component (A) is a resin containing a hydroxyl group-containing resin (A1) as a base resin in combination with a curing agent (A2).
Hydroxyl-containing resin (A1)
  The hydroxyl group-containing resin (A1) is a resin having at least one hydroxyl group in one molecule, and the hydroxyl group-containing resin (A1) is generally 1 to 300 mgKOH / g, from the viewpoint of water resistance of the obtained coating film, etc. It is particularly preferable to have a hydroxyl value in the range of 5 to 250 mgKOH / g, more particularly 10 to 180 mgKOH / g.
  The hydroxyl group-containing resin (A1) can also have an acid group in the molecule. Examples of the acid group include a carboxyl group, a sulfonic acid group, and a phosphoric acid group, and a carboxyl group is particularly preferable.
  When the coating composition of the present invention is used as a water-based coating, it is preferable to make the hydroxyl group-containing resin (A1) water-soluble or water-dispersed by neutralizing an acid group, preferably a carboxyl group, with a basic compound. . Examples of the basic compound include alkali metal or alkaline earth metal hydroxides such as sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, and barium hydroxide; ammonia; ethylamine, propylamine, and butylamine. , Primary amines such as benzylamine, monoethanolamine, neopentanolamine, 2-aminopropanol, 2-amino-2-methyl-1-propanol, 3-aminopropanol; diethylamine, diethanolamine, di-n-propanol Secondary monoamines such as amine, di-iso-propanolamine, N-methylethanolamine, N-ethylethanolamine; dimethylethanolamine, trimethylamine, triethylamine, triisopropylamine, methyldiethanol Amine, 2- (dimethylamino) tertiary monoamines such as ethanol; diethylenetriamine, hydroxyethylaminoethylamine, ethylamino ethylamine, may be mentioned polyamines such as methylamino propylamine. These basic compounds can be used in the range of usually 0.1 to 1.5 equivalents, preferably 0.2 to 1.2 equivalents, relative to the acid groups of the hydroxyl group-containing resin (A1).
  In the present specification, the term “water-based paint” is a term that is contrasted with an organic solvent-type paint, and generally includes a film-forming resin component, a pigment, and the like in water or a medium mainly containing water (aqueous medium). It means a paint that is dispersed and / or dissolved. The coating composition of the present invention is preferably a water-based coating from the viewpoint of reducing environmental load. When the coating composition of the present invention is a water-based coating, the water content in the composition is usually in the range of 10 to 90% by mass, particularly 20 to 80% by mass, more particularly 30 to 60% by mass. Is preferred.
  From the viewpoints of storage stability of the coating composition, water resistance of the resulting coating film and the like, the hydroxyl group-containing resin (A1) is generally 1 to 200 mgKOH / g, particularly 2 to 150 mgKOH / g, more particularly 3 to 80 mgKOH / g. It is preferable to have an acid value within the range. When a hydroxyl group-containing resin having an acid value of 10 mgKOH / g or less is used as the hydroxyl group-containing resin (A1), the hydroxyl group-containing resin and an emulsifier are used instead of neutralizing with the basic compound. It can also be used as a water-based paint by mixing, applying mechanical shearing force and stirring to forcibly disperse the hydroxyl group-containing resin in water.
  Examples of the hydroxyl group-containing resin (A1) include polyester resins, acrylic resins, polyether resins, polycarbonate resins, polyurethane resins, epoxy resins, alkyd resins, and the like. These may be used alone or in combination of two or more. Can do. Among these, the hydroxyl group-containing resin (A1) is preferably at least one selected from the group consisting of a hydroxyl group-containing acrylic resin (A1-1) and a hydroxyl group-containing polyester resin (A1-2). It is more preferable that it is A1-1).
Hydroxyl group-containing acrylic resin (A1-1)
  The hydroxyl group-containing acrylic resin (A1-1) is usually a hydroxyl group-containing polymerizable unsaturated monomer (a) and another polymerizable unsaturated monomer (b) copolymerizable with the hydroxyl group-containing polymerizable unsaturated monomer (a). Can be produced by copolymerization by a method known per se such as a solution polymerization method in an organic solvent and an emulsion polymerization method in an aqueous medium.
  The hydroxyl group-containing polymerizable unsaturated monomer (a) is a compound having at least one hydroxyl group and polymerizable unsaturated bond in one molecule, such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl. Monoesterified products of (meth) acrylic acid such as (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and dihydric alcohols having 2 to 8 carbon atoms; these monoesterified products Ε-caprolactone modified product of: N-hydroxymethyl (meth) acrylamide; allyl alcohol; (meth) acrylate having a polyoxyethylene chain having a hydroxyl group at the molecular end.
  In the present specification, “(meth) acrylate” means acrylate or methacrylate, and “(meth) acrylic acid” means acrylic acid or methacrylic acid. “(Meth) acryloyl” means acryloyl or methacryloyl. Furthermore, “(meth) acrylamide” means acrylamide or methacrylamide.
  The other polymerizable unsaturated monomer (b) copolymerizable with the hydroxyl group-containing polymerizable unsaturated monomer (a) is appropriately selected and used depending on the properties desired for the hydroxyl group-containing acrylic resin (A1-1). be able to. Specific examples of the monomer (b) include those described in the following (i) to (xviii). These can be used alone or in combination of two or more.
(I) alkyl or cycloalkyl (meth) acrylate: for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, tridecyl (meth) Acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) Acrylate, cyclododecyl (meth) acrylate, tricyclodecanyl (meth) acrylate.
(Ii) Polymerizable unsaturated monomer having an isobornyl group: for example, isobornyl (meth) acrylate.
(Iii) Polymerizable unsaturated monomer having an adamantyl group: for example, adamantyl (meth) acrylate and the like.
(Iv) Polymerizable unsaturated monomer having a tricyclodecenyl group: for example, tricyclodecenyl (meth) acrylate.
(V) Aromatic ring-containing polymerizable unsaturated monomer: for example, benzyl (meth) acrylate, styrene, α-methylstyrene, vinyltoluene and the like.
(Vi) Polymerizable unsaturated monomer having an alkoxysilyl group: for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, γ- (meth) acryloyloxypropyltrimethoxysilane, γ- ( (Meth) acryloyloxypropyltriethoxysilane and the like.
(Vii) Polymerizable unsaturated monomer having a fluorinated alkyl group: for example, perfluoroalkyl (meth) acrylate such as perfluorobutylethyl (meth) acrylate and perfluorooctylethyl (meth) acrylate; fluoroolefin and the like.
(Viii) A polymerizable unsaturated monomer having a photopolymerizable functional group such as a maleimide group.
(Ix) Vinyl compound: For example, N-vinylpyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate, vinyl acetate and the like.
(X) Carboxy group-containing polymerizable unsaturated monomer: For example, (meth) acrylic acid, maleic acid, crotonic acid, β-carboxyethyl acrylate, and the like.
(Xi) Nitrogen-containing polymerizable unsaturated monomer: for example, (meth) acrylonitrile, (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N- Dimethylaminopropyl (meth) acrylamide, methylenebis (meth) acrylamide, ethylenebis (meth) acrylamide, 2- (methacryloyloxy) ethyltrimethylammonium chloride, an adduct of glycidyl (meth) acrylate and amines, and the like.
(Xii) A polymerizable unsaturated monomer having two or more polymerizable unsaturated groups in one molecule: for example, allyl (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and the like.
(Xiii) Epoxy group-containing polymerizable unsaturated monomer: for example, glycidyl (meth) acrylate, β-methylglycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 3,4-epoxycyclohexylethyl (meth) ) Acrylate, 3,4-epoxycyclohexylpropyl (meth) acrylate, allyl glycidyl ether and the like.
(Xiv) (meth) acrylate having a polyoxyethylene chain having an alkoxy group at the molecular end.
(Xv) polymerizable unsaturated monomer having a sulfonic acid group: for example, 2-acrylamido-2-methylpropanesulfonic acid, 2-sulfoethyl (meth) acrylate, allylsulfonic acid, 4-styrenesulfonic acid, etc .; Sodium salt, ammonium salt and the like.
(Xvi) polymerizable unsaturated monomer having an ultraviolet absorbing functional group: for example, 2-hydroxy-4- (3-methacryloyloxy-2-hydroxypropoxy) benzophenone, 2-hydroxy-4- (3-acryloyloxy-2) -Hydroxypropoxy) benzophenone, 2,2'-dihydroxy-4- (3-methacryloyloxy-2-hydroxypropoxy) benzophenone, 2,2'-dihydroxy-4- (3-acryloyloxy-2-hydroxypropoxy) benzophenone, 2- (2′-hydroxy-5′-methacryloyloxyethylphenyl) -2H-benzotriazole and the like.
(Xvii) Light-stable polymerizable unsaturated monomer: for example, 4- (meth) acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4- (meth) acryloyloxy-2,2,6, 6-tetramethylpiperidine, 4-cyano-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 1- (meth) acryloyl-4- (meth) acryloylamino-2,2,6 , 6-tetramethylpiperidine, 1- (meth) acryloyl-4-cyano-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6 6-tetramethylpiperidine, 4-crotonoylamino-2,2,6,6-tetramethylpiperidine, 1-crotonoyl-4-crotonoyloxy-2, , 6,6-tetramethylpiperidine and the like.
(Xviii) polymerizable unsaturated monomer having a carbonyl group: for example, acrolein, diacetone acrylamide, diacetone methacrylamide, acetoacetoxyethyl methacrylate, formylstyrol, vinyl alkyl ketone having 4 to 7 carbon atoms (for example, vinyl Methyl ketone, vinyl ethyl ketone, vinyl butyl ketone) and the like.
  The hydroxyl group-containing acrylic resin (A1-1) preferably has an amide group, and the hydroxyl group-containing acrylic resin having such an amide group is, for example, other copolymerizable with the hydroxyl group-containing polymerizable unsaturated monomer (a). It can be produced by using an amide group-containing polymerizable unsaturated monomer such as (meth) acrylamide or N, N-dimethylaminopropyl (meth) acrylamide as at least part of the polymerizable unsaturated monomer (b).
  Further, the hydroxyl group-containing acrylic resin (A1-1) can be used in combination with a so-called urethane-modified acrylic resin that has been extended to a high molecular weight by subjecting a part of the hydroxyl groups in the resin to a urethanization reaction with a polyisocyanate compound. .
  The hydroxyl group-containing polymerizable unsaturated monomer (a) is generally 1 to 50% by mass, preferably 2 to 40% by mass, more preferably 3 to 30%, based on the total amount of the monomer (a) and the monomer (b). It can be used within the range of mass%.
  The hydroxyl group-containing acrylic resin (A1-1) is generally in the range of 1 to 200 mgKOH / g, particularly 2 to 150 mgKOH / g, more particularly 5 to 100 mgKOH / g, from the viewpoints of storage stability and water resistance of the resulting coating film. It is preferable to have a hydroxyl value within the above range.
  The hydroxyl group-containing acrylic resin (A1-1) is also generally within the range of 1 to 200 mgKOH / g, particularly 2 to 150 mgKOH / g, more particularly 5 to 80 mgKOH / g, from the viewpoint of water resistance of the resulting coating film. It preferably has an acid value.
  The hydroxyl group-containing acrylic resin (A1-1) is generally from 2,000 to 5,000,000, particularly from 50,000 to 1,000,000, from the viewpoints of the appearance and water resistance of the coating film obtained. It is particularly preferred to have a weight average molecular weight in the range of 100,000 to 500,000.
  In this specification, the number average molecular weight and the weight average molecular weight are the retention time (retention capacity) measured using a gel permeation chromatograph (GPC) and the retention time of a standard polystyrene with a known molecular weight measured under the same conditions. Based on (retention capacity), it is a value obtained by converting to the molecular weight of polystyrene. Specifically, “HLC-8120GPC” (trade name, manufactured by Tosoh Corporation) is used as a gel permeation chromatograph apparatus, and “TSKgel G4000HXL”, “TSKgel G3000HXL”, “TSKgel G2500HXL” and “TSKgel” are used as columns. G2000HXL "(trade name, all manufactured by Tosoh Corporation), using a differential refractometer as the detector, mobile phase: tetrahydrofuran, measurement temperature: 40 ° C, flow rate: 1 mL / min Can be measured below.
  When the coating composition of the present invention is a water-based paint, the hydroxyl group-containing acrylic resin (A1-1) has one molecule of polymerizable unsaturated group from the viewpoint of the smoothness, sharpness, water resistance, etc. of the formed coating film. 0.1 to 30% by mass of polymerizable unsaturated monomer (c) having at least two in it and 70 to 99.9% by mass of polymerizable unsaturated monomer (d) having one polymerizable unsaturated group in one molecule Copolymer (I) core obtained by copolymerizing, hydroxyl group-containing polymerizable unsaturated monomer (a) 1 to 35% by mass, hydrophobic polymerizable unsaturated monomer (e) 5 to 60% by mass, And a copolymer obtained by copolymerizing 5 to 94% by mass of a polymerizable unsaturated monomer (f) other than the hydroxyl group-containing polymerizable unsaturated monomer (a) and the hydrophobic polymerizable unsaturated monomer (e) (II) ) Shell / core type It is preferably a water-dispersible hydroxy-containing acrylic resin having a structure (A1-1 ').
  Examples of the polymerizable unsaturated monomer (c) having at least two polymerizable unsaturated groups constituting the core include allyl (meth) acrylate, ethylene glycol di (meth) acrylate, Triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, 1 , 4-Butanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, pentaerythritol di (meth) acrylate , Pentaerythritol tetra (meth) acrylate, glycerol di (meth) acrylate, 1,1,1-trishydroxymethyl Ethanedi (meth) acrylate, 1,1,1-trishydroxymethylethanetri (meth) acrylate, 1,1,1-trishydroxymethylpropane tri (meth) acrylate, triallyl isocyanurate , Diallyl terephthalate, divinylbenzene and the like, and these can be used alone or in combination of two or more. The polymerizable unsaturated monomer (c) having at least two polymerizable unsaturated groups in one molecule preferably has an amide group from the viewpoint of the smoothness of the formed coating film. Examples of the unsaturated monomer include methylene bis (meth) acrylamide and ethylene bis (meth) acrylamide.
  The polymerizable unsaturated monomer (c) having at least two polymerizable unsaturated groups in one molecule is generally 0.1 to 30% by mass, preferably based on the total mass of the monomer (c) and the monomer (d). Can be used within the range of 0.5 to 10% by mass, more preferably 1 to 4% by mass.
  Moreover, the polymerizable unsaturated monomer (d) having one polymerizable unsaturated group constituting the core in one molecule is a polymerizable unsaturated monomer (c) having at least two polymerizable unsaturated groups in one molecule. And a compound containing a polymerizable unsaturated group such as a vinyl group or a (meth) acryloyl group in one molecule.
  Specific examples of the polymerizable unsaturated monomer (d) having one polymerizable unsaturated group per molecule include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i -Propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (Meth) acrylate, nonyl (meth) acrylate, tridecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, “isostearyl acrylate” (trade name, manufactured by Osaka Organic Chemical Industry Co., Ltd.), cyclohexyl (meth) Acrylate, methylcyclohexyl ( (C) alkyl or cycloalkyl (meth) acrylate such as acrylate, t-butylcyclohexyl (meth) acrylate, cyclododecyl (meth) acrylate, or the like, and a polymerizable group having an isobornyl group such as isobornyl (meth) acrylate. Saturated monomer; polymerizable unsaturated monomer having adamantyl group such as adamantyl (meth) acrylate; vinyl aromatic compound such as styrene, α-methylstyrene, vinyltoluene; 2-hydroxyethyl (meth) acrylate, 2-hydroxy A monoesterified product of (meth) acrylic acid such as propyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and a dihydric alcohol having 2 to 8 carbon atoms, (Meth) acrylic acid and C2-C8 divalent al Hydroxyl-containing polymerizable unsaturated monomers such as ε-caprolactone modified products of monoesters with coal, allyl alcohol, (meth) acrylates having a polyoxyethylene chain whose molecular terminal is a hydroxyl group; (meth) acrylic acid, maleic Carboxyl group-containing polymerizable unsaturated monomers such as acid, crotonic acid, and β-carboxyethyl acrylate; (meth) acrylonitrile, (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, dimethylaminoethyl (meth) acrylate, glycidyl (meta ) Nitrogen-containing polymerizable unsaturated monomers such as adducts of acrylates and amines, and the like. These can be used alone or in combination of two or more.
  On the other hand, as the hydroxyl group-containing polymerizable unsaturated monomer (a) constituting the shell, as described above, for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3- Monoesterified product of (meth) acrylic acid and dihydric alcohol having 2 to 8 carbon atoms such as hydroxypropyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate; (meth) acrylic acid and 2 to 8 carbon atoms Ε-caprolactone modified product of monoesterified product with dihydric alcohol; allyl alcohol; (meth) acrylate having a polyoxyethylene chain whose molecular terminal is a hydroxyl group, and the like. These can be used in combination.
  The hydroxyl group-containing polymerizable unsaturated monomer (a) is generally 1 to 35% by mass, preferably 6 to 25% by mass, more preferably based on the total mass of the monomer (a), the monomer (e) and the monomer (f). Can be used within a range of 11 to 20% by mass.
  The hydrophobic polymerizable unsaturated monomer (e) constituting the shell is a polymerizable unsaturated monomer containing a straight-chain, branched or cyclic saturated or unsaturated hydrocarbon group having 6 or more carbon atoms. Specifically, for example, n-hexyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, tridecyl (meth) acrylate, lauryl (meth) ) Acrylate, stearyl (meth) acrylate, “isostearyl acrylate” (trade name, manufactured by Osaka Organic Chemical Industry Co., Ltd.), cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) Alkyl or cyclo such as acrylate and cyclododecyl (meth) acrylate Polymerizable unsaturated monomer having an isobornyl group such as isobornyl (meth) acrylate; Polymerizable unsaturated monomer having an adamantyl group such as adamantyl (meth) acrylate; styrene, α-methylstyrene, vinyltoluene, etc. These can be used alone or in combination of two or more. As the hydrophobic polymerizable unsaturated monomer (e) used in the water-dispersible hydroxyl group-containing acrylic resin (A1-1 ′), from the viewpoints of smoothness of the formed coating film, sharpness, etc., among others, vinyl aromatic compounds Is preferred, and styrene is particularly preferred.
  The hydrophobic polymerizable unsaturated monomer (e) is generally 5-60% by weight, in particular 9-40% by weight, more particularly 15%, based on the total amount of monomer (a), monomer (e) and monomer (f). It is preferable to use within a range of ˜25% by mass.
  Examples of the polymerizable unsaturated monomer (f) other than the hydroxyl group-containing polymerizable unsaturated monomer (a) and the hydrophobic polymerizable unsaturated monomer (e) constituting the shell include methyl (meth) acrylate, ethyl ( Alkyl (meth) acrylates such as meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, tert-butyl (meth) acrylate And carboxyl group-containing polymerizable unsaturated monomers such as (meth) acrylic acid, maleic acid, crotonic acid, and β-carboxyethyl acrylate, and the like. These may be used alone or in combination of two or more. it can.
  The polymerizable unsaturated monomer (f) other than the hydroxyl group-containing polymerizable unsaturated monomer (a) and the hydrophobic polymerizable unsaturated monomer (e) is at least one of its components from the viewpoint of ensuring the smoothness of the formed coating film. As part, it is preferable to contain a carboxyl group-containing polymerizable unsaturated monomer (g).
  Examples of the carboxyl group-containing polymerizable unsaturated monomer (g) include (meth) acrylic acid, maleic acid, crotonic acid, β-carboxyethyl acrylate and the like. Among them, (meth) acrylic acid is particularly preferred. Is preferred.
  The carboxyl group-containing polymerizable unsaturated monomer (g) is a monomer (from the viewpoint of the stability of the water-dispersible hydroxyl group-containing acrylic resin (A1-1 ′) in an aqueous medium and the smoothness and water resistance of the formed coating film). It is generally preferable to use within the range of 1 to 40% by mass, particularly 6 to 25% by mass, more particularly 11 to 19% by mass, based on the total mass of a), monomer (e) and monomer (f).
  The water-dispersible hydroxyl group-containing acrylic resin (A1-1 ′) is generally in the range of 1 to 70 mgKOH / g, particularly 2 to 60 mgKOH / g, more particularly 5 to 45 mgKOH / g, from the viewpoint of water resistance of the formed coating film. It is preferable to have a hydroxyl value of
  The water-dispersible hydroxyl group-containing acrylic resin (A1-1 ′) is generally 5 to 90 mgKOH / g, particularly 10 to 70 mgKOH / g, more particularly 15 to 15% from the viewpoint of storage stability and water resistance of the formed coating film. It is preferred to have an acid value in the range of 50 mg KOH / g.
  Furthermore, from the viewpoint of smoothness of the formed coating film, sharpness, etc., as a monomer (a), a monomer (e) and a monomer (f), a polymerizable unsaturated group having only one polymerizable unsaturated group per molecule. It is preferable to use a saturated monomer and make the shell of the water-dispersible hydroxyl group-containing acrylic resin (A1-1 ′) uncrosslinked.
  The water-dispersible hydroxyl group-containing acrylic resin (A1-1 ′) includes, for example, 0.1 to 30% by mass of a polymerizable unsaturated monomer (c) having at least two polymerizable unsaturated groups in one molecule and a polymerizable unsaturated group. Hydroxyl-containing polymerizable unsaturated in an emulsion obtained by emulsion polymerization of a monomer mixture (I) containing 70 to 99.9% by mass of a polymerizable unsaturated monomer (d) having one saturated group per molecule Monomer (a) 1 to 35% by mass, hydrophobic polymerizable unsaturated monomer (e) 5 to 60% by mass, and polymerizable unsaturated monomer (f) other than monomer (a) and monomer (d) 5 to 94% by mass % Monomer mixture (II) can be added and further polymerized.
  Emulsion polymerization of the monomer mixture can be performed by a method known per se, for example, using a polymerization initiator in the presence of an emulsifier.
  As the emulsifier, an anionic emulsifier or a nonionic emulsifier is suitable. Examples of the anionic emulsifier include sodium salts and ammonium salts of organic acids such as alkyl sulfonic acid, alkyl benzene sulfonic acid, and alkyl phosphoric acid. Nonionic emulsifiers include, for example, polyoxyethylene oleyl ether, Polyoxyethylene stearyl ether, polyoxyethylene lauryl ether, polyoxyethylene tridecyl ether, polyoxyethylene phenyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene monolaurate, polyoxyethylene mono Stearate, polyoxyethylene monooleate, sorbitan monolaurate, sorbitan monostearate, sorbitan monostearate, sorbitan trioleate , Polyoxyethylene sorbitan monolaurate, and the like.
  An anionic emulsifier containing a polyoxyalkylene group having an anionic group and a polyoxyalkylene group such as a polyoxyethylene group or a polyoxypropylene group in one molecule, or the anionic group and a radically polymerizable unsaturated group in one molecule A reactive anionic emulsifier may be used, and among them, it is preferable to use a reactive anionic emulsifier.
  Examples of the reactive anionic emulsifier include sodium salts and ammonium salts of sulfonic acid compounds having radically polymerizable unsaturated groups such as (meth) allyl groups, (meth) acryloyl groups, propenyl groups, and butenyl groups. . Among these, an ammonium salt of a sulfonic acid compound having a radical polymerizable unsaturated group is preferable because the formed coating film is excellent in water resistance. Examples of the ammonium salt of the sulfonic acid compound include commercially available products such as “Latemul S-180A” (trade name, manufactured by Kao Corporation).
  Among the ammonium salts of sulfonic acid compounds having a radical polymerizable unsaturated group, ammonium salts of sulfonic acid compounds having a radical polymerizable unsaturated group and a polyoxyalkylene group are more preferable. Examples of the ammonium salt of a sulfonic acid compound having a radically polymerizable unsaturated group and a polyoxyalkylene group include “AQUALON KH-10” (trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), “SR-1025A” (product) Name, manufactured by Asahi Denka Kogyo Co., Ltd.).
  The emulsifier is usually used in a range of 0.1 to 15% by mass, preferably 0.5 to 10% by mass, more preferably 1 to 5% by mass, based on the total amount of all monomers used. be able to.
  The polymerization initiator may be any of oil-soluble and water-soluble types. For example, benzoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, cumene hydroperoxide, tert- Organic peroxides such as butyl peroxide, tert-butyl peroxylaurate, tert-butyl peroxyisopropyl carbonate, tert-butyl peroxyacetate, diisopropylbenzene hydroperoxide; azobisisobutyronitrile, azobis (2, 4-dimethylvaleronitrile), azobis (2-methylpropiononitrile), azobis (2-methylbutyronitrile), 4,4′-azobis (4-cyanobutanoic acid), dimethylazobis (2-methylpropyl) Pionate), azo compounds such as azobis [2-methyl-N- (2-hydroxyethyl) -propionamide], azobis {2-methyl-N- [2- (1-hydroxybutyl)]-propionamide}; Examples thereof include persulfates such as potassium sulfate, ammonium persulfate, and sodium persulfate. These can be used alone or in combination of two or more.
  In addition, if necessary, for example, a reducing agent such as sugar, sodium formaldehyde sulfoxylate, or iron complex may be used in combination with the polymerization initiator to form a redox polymerization system.
  It is preferable to use the said polymerization initiator in the range of 0.1-5 mass% normally based on the total mass of all the monomers used, especially 0.2-3 mass%. The method for adding the polymerization initiator is not particularly limited, and can be appropriately selected depending on the type and amount thereof. For example, the polymerization initiator may be previously contained in the monomer mixture or the aqueous medium, or may be added all at once during the polymerization, or may be added dropwise.
  The water-dispersible hydroxyl group-containing acrylic resin (A1-1 ′) is prepared by adding the hydroxyl group-containing polymerizable unsaturated monomer (a), the hydrophobic polymerizable unsaturated monomer (e) and the monomer ( It can be obtained by adding a monomer mixture (II) containing a polymerizable unsaturated monomer (f) other than a) and monomer (e) and further polymerizing.
  The monomer mixture (II) can appropriately contain components such as a polymerization initiator, a chain transfer agent, a reducing agent, and an emulsifier as listed above, if necessary.
  The monomer mixture (II) can be dropped as it is, but it is desirable to disperse the monomer mixture (II) in an aqueous medium and drop it as a monomer emulsion. In this case, the particle size of the monomer emulsion is not particularly limited.
  The polymerization of the monomer mixture (II) can be carried out, for example, by adding the monomer mixture (II), which may be emulsified, all at once or dropwise to the emulsion and heating to an appropriate temperature while stirring.
  The water-dispersible hydroxyl group-containing acrylic resin (A1-1 ′) obtained as described above comprises a polymerizable unsaturated monomer (c) having at least two polymerizable unsaturated groups in one molecule and a polymerizable unsaturated group. A copolymer (I) formed from a monomer mixture (I) containing a polymerizable unsaturated monomer (d) having 1 in a molecule, a hydroxyl group-containing polymerizable unsaturated monomer (a), hydrophobic A copolymer (II) formed from a monomer mixture (II) containing a polymerizable polymerizable unsaturated monomer (e) and a polymerizable unsaturated monomer (f) other than the monomers (a) and (e) It can have a core / shell type multilayer structure.
  In addition, the water-dispersible hydroxyl group-containing acrylic resin (A1-1 ′) is a polymerizable resin that forms another resin layer between the step of obtaining the copolymer (I) and the step of obtaining the copolymer (II). It is good also as a resin particle which consists of three layers or more by adding the process which supplies a saturated monomer (1 type, or 2 or more types of mixtures), and performs emulsion polymerization.
  In the present invention, the “shell” of the water-dispersible hydroxyl group-containing acrylic resin (A1-1 ′) means a polymer layer present in the outermost layer of the resin particles, and the “core” is a resin particle excluding the shell portion. This means an inner polymer layer, and the “core / shell structure” means a structure having the above core and shell. The core / shell type structure is generally a layer structure in which the core is completely covered with the shell. However, depending on the mass ratio of the core to the shell, the amount of the monomer of the shell may form the layer structure. It may be insufficient. In such a case, it is not necessary to have a complete layer structure as described above, and it may be a structure in which a part of the core is covered with a shell, or a polymerizable part which is a constituent element of the shell on a part of the core. A structure in which an unsaturated monomer is graft-polymerized may also be used. Further, the concept of the multilayer structure in the core / shell structure is similarly applied to the case where the multilayer structure is formed in the core in the water-dispersible hydroxyl group-containing acrylic resin (A1-1 ′).
  The ratio of the copolymer (I) and the copolymer (II) in the water-dispersible hydroxyl group-containing acrylic resin (A1-1 ′) having a core / shell type reversal structure is the flip-flop property of the formed coating film, metallic unevenness From the standpoint of the above, the solid content mass ratio of copolymer (I) / copolymer (II) is generally 10/90 to 90/10, particularly 50/50 to 85/15, more particularly 65/35 to 80. It is preferably within the range of / 20.
  The water-dispersible hydroxyl group-containing acrylic resin (A1-1 ') obtained as described above can generally have an average particle diameter in the range of 10 to 1000 nm, particularly 20 to 500 nm. The average particle diameter of the hydroxyl group-containing acrylic resin is a value measured by a Coulter counter method at a measurement temperature of 20 ° C. This measurement can be performed using, for example, “COULTER N4 type” (trade name, manufactured by Beckman Coulter, Inc.).
  In order to improve the mechanical stability of the aqueous dispersion particles of the resulting water-dispersible hydroxyl group-containing acrylic resin (A1-1 ′), the carboxyl group and the like of the water-dispersible hydroxyl group-containing acrylic resin (A1-1 ′) It is desirable to neutralize acidic groups with a neutralizing agent. The neutralizing agent is not particularly limited as long as it can neutralize acidic groups, and examples thereof include sodium hydroxide, potassium hydroxide, trimethylamine, 2- (dimethylamino) ethanol, Examples include 2-amino-2-methyl-1-propanol, triethylamine, aqueous ammonia, and the like. These neutralizing agents are water-dispersible hydroxyl group-containing acrylic resins (A1-1 ′) after neutralization. It is desirable to use such an amount that the pH is about 6.5 to about 9.0.
Hydroxyl-containing polyester resin (A1-2)
  In the coating composition of the present invention, the smoothness of the coating film obtained can be improved by using the hydroxyl group-containing polyester resin (A1-2) as the base resin of the hydroxyl group-containing resin component (A).
  The hydroxyl group-containing polyester resin (A1-2) can be usually produced by an esterification reaction or an ester exchange reaction between an acid component and an alcohol component.
  As said acid component, the compound normally used as an acid component can be used at the time of manufacture of a polyester resin. Examples of the acid component include an aliphatic polybasic acid, an alicyclic polybasic acid, an aromatic polybasic acid, and the like.
  The aliphatic polybasic acid generally includes an aliphatic compound having two or more carboxyl groups in one molecule, an acid anhydride of the aliphatic compound, and an esterified product of the aliphatic compound. Are, for example, aliphatic polycarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, octadecanedioic acid, citric acid, etc. An anhydride of the aliphatic polyvalent carboxylic acid; and a lower alkyl esterified product of the aliphatic polyvalent carboxylic acid having 1 to 6, preferably 1 to 4 carbon atoms. The above aliphatic polybasic acids can be used alone or in combination of two or more. As the aliphatic polybasic acid, it is particularly preferable to use adipic acid and / or adipic anhydride from the viewpoint of the smoothness of the resulting coating film.
  The alicyclic polybasic acid generally includes a compound having one or more alicyclic structures and two or more carboxyl groups in one molecule, an acid anhydride of the compound, and an esterified product of the compound. The alicyclic structure can be mainly a 4-6 membered ring structure. Specific examples of the alicyclic polybasic acid include 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and 4-cyclohexene-1,2-dicarboxylic acid. , 3-methyl-1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,3,5-cyclohexanetricarboxylic acid, etc. Examples thereof include monovalent carboxylic acids; anhydrides of the alicyclic polyvalent carboxylic acids; lower alkyl esterified products of the alicyclic polyvalent carboxylic acids having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms. The above alicyclic polybasic acids can be used alone or in combination of two or more. As said alicyclic polybasic acid, from a smoothness viewpoint of the coating film obtained, 1, 2- cyclohexane dicarboxylic acid, 1, 2- cyclohexane dicarboxylic acid anhydride, 1, 3- cyclohexane dicarboxylic acid, 1, 4 -Cyclohexanedicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic anhydride are preferably used, among which 1,2-cyclohexanedicarboxylic acid and / or 1,2 -More preferred is the use of cyclohexanedicarboxylic anhydride.
  The aromatic polybasic acid generally includes an aromatic compound having two or more carboxyl groups in one molecule, an acid anhydride of the aromatic compound, and an esterified product of the aromatic compound. Specifically, For example, aromatic polyvalent carboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid, trimellitic acid, pyromellitic acid; anhydride of the aromatic polyvalent carboxylic acid A lower alkyl esterified product of the aromatic polycarboxylic acid having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms. The above aromatic polybasic acids can be used alone or in combination of two or more. Among these aromatic polybasic acids, phthalic acid, phthalic anhydride, isophthalic acid, trimellitic acid, and trimellitic anhydride are preferably used.
  Moreover, acid components other than the said aliphatic polybasic acid, alicyclic polybasic acid, and aromatic polybasic acid can also be used. The acid component is not particularly limited, and examples thereof include coconut oil fatty acid, cottonseed oil fatty acid, hemp seed oil fatty acid, rice bran oil fatty acid, fish oil fatty acid, tall oil fatty acid, soybean oil fatty acid, linseed oil fatty acid, tung oil fatty acid, rapeseed Fatty acids such as oil fatty acid, castor oil fatty acid, dehydrated castor oil fatty acid, safflower oil fatty acid; lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, benzoic acid, p-tert-butylbenzoic acid Examples thereof include monocarboxylic acids such as acid, cyclohexane acid, and 10-phenyloctadecanoic acid; hydroxycarboxylic acids such as lactic acid, 3-hydroxybutanoic acid, and 3-hydroxy-4-ethoxybenzoic acid. These acid components can be used alone or in combination of two or more.
  As the alcohol component, a polyhydric alcohol having at least two hydroxyl groups in one molecule can be preferably used. Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, diethylene glycol, trimethylene glycol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3 -Butanediol, 1,2-butanediol, 3-methyl-1,2-butanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,2-pentanediol, 1,5-pentanediol 1,4-pentanediol, 2,4-pentanediol, 2,3-dimethyltrimethylene glycol, tetramethylene glycol, 3-methyl-4,3-pentanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentane 1,6-hexanediol, 1,5-hexanediol, 1,4-hexanediol, 2,5-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, water Dihydric alcohols such as hydrogenated bisphenol A, hydrogenated bisphenol F, and dimethylolpropionic acid; polylactone diols obtained by adding lactones such as ε-caprolactone to these dihydric alcohols; ester diols such as bis (hydroxyethyl) terephthalate An alkylene oxide adduct of bisphenol A, a polyether diol such as polyethylene glycol, polypropylene glycol and polybutylene glycol; glycerin, trimethylolethane, trimethylolpropane, diglycerin, triglyceride Trihydric or higher alcohols such as phosphorus, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol, tris (2-hydroxyethyl) isocyanuric acid, sorbitol, mannitol, and the like. And polylactone polyols to which lactones such as caprolactone are added.
  Moreover, alcohol components other than the said polyhydric alcohol can also be used. The alcohol component is not particularly limited, and examples thereof include monoalcohols such as methanol, ethanol, propyl alcohol, butyl alcohol, stearyl alcohol, and 2-phenoxyethanol; propylene oxide, butylene oxide, “Cardura E10” (trade name) And alcohol compounds obtained by reacting monoepoxy compounds such as HEXION Specialty Chemicals, Inc. (glycidyl esters of synthetic highly branched saturated fatty acids) and acids.
  The manufacturing method of a hydroxyl-containing polyester resin (A1-2) is not specifically limited, It can carry out according to a normal method. For example, by heating the acid component and the alcohol component in a nitrogen stream at a temperature of about 150 to about 250 ° C. for about 5 to 10 hours, and performing an esterification reaction or a transesterification reaction of the acid component and the alcohol component. A hydroxyl group-containing polyester resin (A1-2) can be produced.
  When the acid component and the alcohol component are esterified or transesterified, these components may be added to the reaction vessel at one time, or one or both may be added in several portions. Good. First, after synthesizing a hydroxyl group-containing polyester resin, the resulting hydroxyl group-containing polyester resin is reacted with an acid anhydride to undergo half esterification, whereby a carboxyl group- and hydroxyl group-containing polyester resin can be produced. Furthermore, after synthesizing a carboxyl group-containing polyester resin, the alcohol component may be added to produce a hydroxyl group-containing polyester resin.
  In the esterification or transesterification reaction, in order to promote the reaction, dibutyltin oxide, antimony trioxide, zinc acetate, manganese acetate, cobalt acetate, calcium acetate, lead acetate, tetrabutyl titanate, tetraisopropyl titanate, etc. A catalyst known per se can be used.
  The hydroxyl group-containing polyester resin (A1-2) can be modified with a fatty acid, a monoepoxy compound, a polyisocyanate compound or the like during or after the production of the resin.
  Examples of fatty acids that can be used for modification include coconut oil fatty acid, cottonseed oil fatty acid, hempseed oil fatty acid, rice bran oil fatty acid, fish oil fatty acid, tall oil fatty acid, soybean oil fatty acid, linseed oil fatty acid, tung oil fatty acid, rapeseed oil fatty acid, castor oil Fatty acid, dehydrated castor oil fatty acid, safflower oil fatty acid and the like can be mentioned. Examples of the monoepoxy compound that can be used for modification include “Cardura E10” (trade name, manufactured by HEXION Specialty Chemicals, a synthetic highly branched saturated fatty acid glycidyl. Ester).
  Examples of polyisocyanate compounds that can be used for modification include aliphatic diisocyanates such as lysine diisocyanate, hexamethylene diisocyanate, and trimethylhexane diisocyanate; hydrogenated xylylene diisocyanate, isophorone diisocyanate, methylcyclohexane-2,4-diisocyanate, Alicyclic diisocyanates such as methylcyclohexane-2,6-diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), 1,3- (isocyanatomethyl) cyclohexane; tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, etc. Aromatic diisocyanates; organic polyisocyanates such as triisocyanates and higher polyisocyanates such as lysine triisocyanate Adduct of each of these organic polyisocyanates with polyhydric alcohol, low molecular weight polyester resin, water, etc .; cyclized polymer (for example, isocyanurate) between these organic polyisocyanates, biuret type addition Thing etc. are mentioned. These polyisocyanate compounds can be used alone or in admixture of two or more.
  As the hydroxyl group-containing polyester resin (A1-2), the total content of aliphatic polybasic acid and alicyclic polybasic acid in the acid component of the raw material from the viewpoint of excellent smoothness and chipping resistance of the resulting coating film However, based on the total amount of the acid component, those generally in the range of 30 to 100 mol%, particularly 40 to 97 mol%, more particularly 50 to 95 mol% are preferable. In particular, from the viewpoint that the resulting coating film has excellent chipping resistance, the aliphatic polybasic acid is adipic acid and / or adipic acid anhydride, and the alicyclic polybasic acid is 1,2-cyclohexanedicarboxylic acid and It is preferable that it is / or 1,2-cyclohexanedicarboxylic anhydride.
  The hydroxyl group-containing polyester resin (A1-2) is generally 10 to 300 mgKOH / g, particularly 50 to 250 mgKOH / g, more particularly 80 to 180 mgKOH / g in terms of water resistance of the resulting coating film. It is preferable to have
  When the hydroxyl group-containing polyester resin (A1-2) further has a carboxyl group, it is generally 1 to 200 mgKOH / g, particularly 15 to 100 mgKOH / g, more particularly 20 to 60 mgKOH / g, from the viewpoint of water resistance of the resulting coating film. It is preferable to have an acid value in the range of g.
  In addition, the hydroxyl group-containing polyester resin (A1-2) is generally 500 to 50,000, particularly 1,000 to 30,000, more particularly 1,200, from the viewpoint of the smoothness and water resistance of the resulting coating film. It is preferred to have a number average molecular weight in the range of -10,000.
  When the coating composition of the present invention is an aqueous paint, the hydroxyl group-containing polyester resin (A1-2) preferably has a carboxyl group. In this case, the hydroxyl group-containing polyester resin (A1-2) is generally 1 to 1 It is preferred to have an acid value in the range of 200 mg KOH / g, in particular 15-100 mg KOH / g, more particularly 20-60 mg KOH / g.
  In the coating composition of the present invention, the base resin in the film-forming resin component (A) is a resin containing substantially no hydroxyl group other than the hydroxyl group-containing resin (A1) (hereinafter referred to as “hydroxyl group-free resin”). ) (A3) can also be used.
Hydroxyl-free resin (A3)
  Examples of the hydroxyl group-free resin (A3) include polyurethane resin, polyester resin, acrylic resin, alkyd resin, silicon resin, fluororesin, epoxy resin, and the like, such as chipping resistance and water resistance of the resulting coating film. From the viewpoint, polyurethane resin is particularly preferable. These resins can have a functional group such as a carboxyl group and an epoxy group, and particularly preferably have a carboxyl group. These resins can be used alone or in combination of two or more, but it is usually preferable to use them in combination with the hydroxyl group-containing resin (A1).
  Examples of the polyurethane resin include aliphatic and / or alicyclic diisocyanates; at least one diol selected from the group consisting of polyether diols, polyester diols, and polycarbonate diols; low molecular weight polyhydroxy compounds and dimethanol alkanoic acids. A urethane prepolymer is produced by reaction, neutralized with a tertiary amine, emulsified and dispersed in water, and then an aqueous solution containing a chain extender such as polyamine, a crosslinking agent and / or a terminator as necessary. A self-emulsifying urethane emulsion (A3-1) etc. obtained by mixing with a medium and reacting until the isocyanate groups are substantially eliminated, having an average particle size in the range of about 0.001 to about 3 μm, etc. Can be mentioned. As this urethane emulsion, commercial items, such as a brand name "Yukot UX-5000" and a brand name "Yukot UX-8100" (all are the Sanyo Chemical Industries Ltd. make), can be mentioned, for example.
Curing agent (A2)
  The curing agent (A2) can cure the coating composition of the present invention by reacting with the hydroxyl groups present in the hydroxyl group-containing resin (A1) and possibly crosslinkable functional groups such as carboxyl groups and epoxy groups. It is a functional group-containing compound. Examples of the curing agent (A2) include amino resins, polyisocyanate compounds, blocked polyisocyanate compounds, epoxy group-containing compounds, carboxyl group-containing compounds, carbodiimide group-containing compounds, and the like. These can be used in combination. Of these, amino resins, polyisocyanate compounds and blocked polyisocyanate compounds capable of reacting with hydroxyl groups are preferred from the viewpoint of water resistance and chipping resistance of the resulting coating film, and moreover, from the viewpoint of storage stability of the resulting paint. Amino resins are particularly preferred.
  As said amino resin, the partial methylolation amino resin obtained by reaction of an amino component and an aldehyde component, or a complete methylolation amino resin can be used. Examples of the amino component include melamine, urea, benzoguanamine, acetoguanamine, steroguanamine, spiroguanamine, dicyandiamide and the like. Examples of the aldehyde component include formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde, and the like.
  Those obtained by partially or completely etherifying the methylol group of the methylolated amino resin with an appropriate alcohol can also be used. Examples of alcohols that can be used for etherification include methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, 2-ethyl-1-butanol, and 2-ethyl-1. -Hexanol etc. are mentioned.
  As the amino resin, a melamine resin is preferable. In particular, methyl ether melamine resins in which methylol groups of partially or fully methylolated melamine resins are partially or completely etherified with methyl alcohol, methylol groups of partially or fully methylolated melamine resins are partially or completely with butyl alcohol. Preferred is a methyl-butyl mixed etherified melamine resin in which the methylol group of a partially or completely methylolated melamine resin is partially or completely etherified with methyl alcohol and butyl alcohol. Etherified melamine resins are more preferred.
  Among these, from the viewpoint that a multilayer coating film excellent in sharpness and water resistance can be obtained, as the hydroxyl group-containing resin (A1), aliphatic polybasic acid and alicyclic polybasic acid in the raw acid component are used. Produced using an acid component having a total content in the range of 30 to 97 mol% and a content of aromatic polybasic acid in the range of 3 to 70 mol% based on the total amount of the acid components A hydroxyl group-containing polyester resin is used, and at least one alkyl etherified melamine resin selected from the methyl etherified melamine resin, butyl etherified melamine resin and methyl-butyl mixed etherified melamine resin is used as the curing agent (A2). The coating composition is particularly suitable.
  The melamine resin preferably has a weight average molecular weight in the range of generally 400 to 6,000, particularly 700 to 4,000, more particularly 1,000 to 3,000.
  Commercially available products can be used as the melamine resin. Specifically, for example, “Cymel 202”, “Cymel 203”, “Cymel 204”, “Cymel 211”, “Cymel 238”, “Cymel 251”, “Cymel 303”. ”,“ Cymel 323 ”,“ Cymel 324 ”,“ Cymel 325 ”,“ Cymel 327 ”,“ Cymel 350 ”,“ Cymel 385 ”,“ Cymel 1156 ”,“ Cymel 1158 ”,“ Cymel 1116 ”,“ Cymel 1130 ” (The above is a product name made by Nihon Cytec Industries, Ltd., “Uban 120”, “Uban 20HS”, “Uban 20SE60”, “Uban 2021”, “Uban 2028”, “Uban 28-60” (above, Mitsui Chemicals). Company name, product name) and the like.
  When a melamine resin is used as the curing agent (A2), sulfonic acids such as p-toluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid; monobutyl phosphoric acid, dibutyl phosphoric acid, mono 2-ethylhexyl phosphoric acid, di-2 -Alkyl phosphate esters such as ethylhexyl phosphate; salts of these acids with amines can be used as catalysts.
  The polyisocyanate compound is a compound having at least two isocyanate groups in one molecule. For example, aliphatic polyisocyanate, alicyclic polyisocyanate, araliphatic polyisocyanate, aromatic polyisocyanate, Derivatives and the like are included.
  Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3. -Aliphatic diisocyanates such as butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, dimer acid diisocyanate, methyl 2,6-diisocyanatohexanoate (common name: lysine diisocyanate); 2 , 6-Diisocyanatohexanoic acid 2-isocyanatoethyl, 1,6-diisocyanato-3-isocyanatomethylhexane, 1,4,8-triisocyanatooctane, 1,6,6 1-triisocyanatoundecane, 1,8-diisocyanato-4-isocyanatomethyloctane, 1,3,6-triisocyanatohexane, 2,5,7-trimethyl-1,8-diisocyanato-5-isocyanatomethyl Examples thereof include aliphatic triisocyanates such as octane.
  Examples of the alicyclic polyisocyanate include 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (common name) : Isophorone diisocyanate), methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,3- or 1,4-bis (isocyanatomethyl) cyclohexane (common name: hydrogenated xylylene diisocyanate) or The mixture, alicyclic diisocyanate such as norbornane diisocyanate; 1,3,5-triisocyanatocyclohexane, 1,3,5-trimethylisocyanatocyclohexane, 2- (3-iso Anatopropyl) -2,5-di (isocyanatomethyl) -bicyclo (2.2.1) heptane, 2- (3-isocyanatopropyl) -2,6-di (isocyanatomethyl) -bicyclo (2. 2.1) Heptane, 3- (3-isocyanatopropyl) -2,5-di (isocyanatomethyl) -bicyclo (2.2.1) heptane, 5- (2-isocyanatoethyl) -2-isocyanate Natomethyl-3- (3-isocyanatopropyl) -bicyclo (2.2.1) heptane, 6- (2-isocyanatoethyl) -2-isocyanatomethyl-3- (3-isocyanatopropyl) -bicyclo (2.2.1) heptane, 5- (2-isocyanatoethyl) -2-isocyanatomethyl-2- (3-isocyanatopropyl) -bicyclo (2.2.1) -heptane, 6- (2 -B Shianatoechiru) -2-isocyanatomethyl-2- (3-isocyanatopropyl) - bicyclo (2.2.1) may be mentioned alicyclic triisocyanates such heptane and the like.
  Examples of the araliphatic polyisocyanate include 1,3- or 1,4-xylylene diisocyanate or a mixture thereof, ω, ω′-diisocyanato-1,4-diethylbenzene, 1,3- or 1,4-bis. Aromatic aliphatic diisocyanates such as (1-isocyanato-1-methylethyl) benzene (common name: tetramethylxylylene diisocyanate) or mixtures thereof; aromatic aliphatic triisocyanates such as 1,3,5-triisocyanatomethylbenzene, etc. Can be mentioned.
  Examples of the aromatic polyisocyanate include m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 2,4′- or 4,4′-diphenylmethane diisocyanate or the like. Mixtures, 2,4- or 2,6-tolylene diisocyanate or mixtures thereof, aromatic diisocyanates such as 4,4′-toluidine diisocyanate, 4,4′-diphenyl ether diisocyanate; triphenylmethane-4,4 ′, 4 ′ Aromatic triisocyanates such as '-triisocyanate, 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene; 4,4'-diphenylmethane-2,2', 5,5'- Tetraisocyanate And aromatic tetraisocyanates such as the over bets like.
  Examples of the polyisocyanate derivative include, for example, the dimer, trimer, biuret, allophanate, uretdione, uretoimine, isocyanurate, oxadiazine trione, polymethylene polyphenyl polyisocyanate (crude MDI, polymeric MDI) of the above polyisocyanate compound, Examples include Crude TDI.
  The above polyisocyanates and derivatives thereof may be used alone or in combination of two or more. Among these polyisocyanates, it is preferable to use aliphatic diisocyanates, alicyclic diisocyanates, and derivatives thereof singly or in combination of two or more.
  In addition, as the polyisocyanate compound, a prepolymer obtained by urethanating the polyisocyanate and the derivative thereof with a polyhydric alcohol, a low molecular weight polyester resin, or water under an isocyanate group-excess condition can also be used.
  The polyisocyanate compound has an equivalent ratio (NCO / OH) of the isocyanate group in the polyisocyanate compound and the hydroxyl group in the hydroxyl group-containing resin (A1) of usually 0.5 to 5 from the viewpoint of water resistance of the resulting coating film. It is preferable to use it at a ratio of 2.0, particularly 0.8 to 1.5.
  The blocked polyisocyanate compound is a compound obtained by blocking an isocyanate group of a polyisocyanate compound having at least two isocyanate groups in one molecule with a blocking agent.
  Examples of the polyisocyanate compound having at least two isocyanate groups in one molecule include aliphatic diisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, dimer acid diisocyanate, and lysine diisocyanate; hydrogenated xylylene diisocyanate, cyclohexylene Cycloaliphatic diisocyanates such as diisocyanate and isophorone diisocyanate; Aromatic diisocyanates such as tolylene diisocyanate, phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, naphthalene diisocyanate; 2-isocyanato Ethyl-2,6-diisocyanatocaproate, 3-isocyanate Trivalent or higher organic polyisocyanate compounds such as tomethyl-1,6-hexamethylene diisocyanate, 4-isocyanatomethyl-1,8-octamethylene diisocyanate (common name, triaminononane triisocyanate); 2 of these polyisocyanate compounds Examples include prepolymers obtained by subjecting these polyisocyanate compounds and polyhydric alcohols, low molecular weight polyester resins, or water to a urethanization reaction under an excess of isocyanate groups. .
  Examples of the blocking agent include phenols such as phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonylphenol, octylphenol, methyl hydroxybenzoate; ε-caprolactam, δ-valero Lactams such as lactam, γ-butyrolactam, β-propiolactam; aliphatic alcohols such as methanol, ethanol, propyl alcohol, butyl alcohol, amyl alcohol, lauryl alcohol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene Glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, Ethers such as propylene glycol monomethyl ether and methoxymethanol; benzyl alcohol, glycolic acid, methyl glycolate, ethyl glycolate, butyl glycolate, lactic acid, methyl lactate, ethyl lactate, butyl lactate, methylol urea, methylol melamine, diacetone alcohol Alcohols such as 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate; oximes such as formamide oxime, acetamide oxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, cyclohexane oxime; dimethyl malonate, diethyl malonate , Active methylenes such as ethyl acetoacetate, methyl acetoacetate, acetylacetone; butyl mercaptan, t-butylmer Mercaptans such as captan, hexyl mercaptan, t-dodecyl mercaptan, 2-mercaptobenzothiazole, thiophenol, methylthiophenol, ethylthiophenol; acetanilide, acetanisid, acetolide, acrylamide, methacrylamide, acetic acid amide, stearamide, benzamide, etc. Acid amides; succinimides, phthalic imides, maleic imides and other imides; diphenylamines, phenylnaphthylamines, xylidines, N-phenylxylidines, carbazoles, anilines, naphthylamines, butylamines, dibutylamines, butylphenylamines, etc. Imidazole system such as imidazole and 2-ethylimidazole; urea, thiourea, ethyleneurea, ethylenethiourea, dipheny Examples include ureas such as urea; carbamates such as phenyl N-phenylcarbamate; imines such as ethyleneimine and propyleneimine; sulfites such as sodium bisulfite and potassium bisulfite; and azole compounds. . Examples of the azole compounds include pyrazole, 3,5-dimethylpyrazole, 3-methylpyrazole, 4-benzyl-3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole, 4-bromo-3, Pyrazole or pyrazole derivatives such as 5-dimethylpyrazole and 3-methyl-5-phenylpyrazole; Imidazole or imidazole derivatives such as imidazole, benzimidazole, 2-methylimidazole, 2-ethylimidazole and 2-phenylimidazole; 2-methylimidazoline And imidazoline derivatives such as 2-phenylimidazoline.
  Of these, oxime-based blocking agents, active methylene-based blocking agents, pyrazoles or pyrazole derivatives are particularly suitable.
  As the blocking agent, a hydroxycarboxylic acid having one or more hydroxyl groups and one or more carboxyl groups, for example, hydroxypivalic acid, dimethylolpropionic acid, or the like can also be used.
  When the coating composition of the present invention is an aqueous coating, after blocking the isocyanate group using the hydroxycarboxylic acid, a blocked polyisocyanate compound imparted with water dispersibility by neutralizing the carboxyl group of the hydroxycarboxylic acid It can be used suitably.
  In addition, when the hydroxyl group-containing resin (A1) and / or the hydroxyl group-free resin (A3) has a crosslinkable functional group such as a carboxyl group or an epoxy group, a crosslinking agent that can react with the functional group as a curing agent (A2). A curing agent having a functional functional group can be used.
  Examples of such a curing agent include an epoxy group-containing compound, a carboxyl group-containing compound, a carbodiimide group-containing compound and the like that can react with the crosslinkable functional group, and among them, polycarbodiimide that can react with a carboxyl group. Compounds are preferred.
  The polycarbodiimide compound is a compound having at least two carbodiimide groups in one molecule. For example, a compound obtained by subjecting isocyanate groups of an isocyanate group-containing compound to a carbon dioxide removal reaction can be used.
  When the coating composition of the present invention is a water-based coating, it is preferable to use a water-soluble or water-dispersible polycarbodiimide compound as the polycarbodiimide compound from the viewpoint of the smoothness of the resulting coating film. As the water-soluble or water-dispersible polycarbodiimide compound, any polycarbodiimide compound that can be stably dissolved or dispersed in an aqueous medium can be used without particular limitation.
  Specific examples of the water-soluble polycarbodiimide compound include “Carbodilite SV-02”, “Carbodilite V-02”, “Carbodilite V-02-L2”, “Carbodilite V-04” (trade names, both) Commercial products such as Nisshinbo Co., Ltd.) can be used. Moreover, as said water dispersible polycarbodiimide compound, commercial items, such as "Carbodilite E-01" and "Carbodilite E-02" (Brand name, all are the Nisshinbo Co., Ltd.), can be used, for example.
  The said polycarbodiimide compound can be used individually or in combination of 2 or more types, respectively.
  The use ratio of the hydroxyl group-containing resin (A1) and the curing agent (A2) in the coating composition of the present invention is based on the total amount of both from the viewpoint of improving the adhesion of the coating film and the chipping resistance. The resin (A1) is generally in the range of 30 to 95% by weight, especially 50 to 90% by weight, more particularly 60 to 80% by weight, and the curing agent (A2) is generally 5 to 70% by weight, in particular 10 to 50% by weight. Furthermore, it is particularly preferable that the content be in the range of 20 to 40% by mass.
  When the hydroxyl group-containing resin (A1) contains the hydroxyl group-containing acrylic resin (A1-1) as at least a part of the hydroxyl group-containing resin (A1-1), the content of the hydroxyl group-containing acrylic resin (A1-1) in the coating composition of the present invention is Based on the total amount of A1) and curing agent (A2), it is generally in the range of 2 to 80% by weight, in particular 10 to 60% by weight, more particularly 20 to 50% by weight.
  When the hydroxyl group-containing resin (A1) contains the hydroxyl group-containing polyester resin (A1-2) as at least a part thereof, the content of the hydroxyl group-containing polyester resin (A1-2) in the coating composition of the present invention is as follows. Based on the total amount of A1) and curing agent (A2), it is generally in the range of 2 to 80% by weight, in particular 5 to 60% by weight, more particularly 10 to 50% by weight.
  When the coating composition of this invention contains the above-mentioned urethane emulsion (A3-1), content of a urethane emulsion (A3-1) is 100 mass parts in total of a hydroxyl-containing resin (A1) and a hardening | curing agent (A2). Generally, it is preferable that the content is in the range of 1 to 80 parts by mass, particularly 5 to 60 parts by mass, more particularly 10 to 40 parts by mass.
Talc (B)
  In the coating composition of the present invention, as the talc (B), in the volume-based particle size distribution, the particle size (D) where the integrated particle size distribution from the small particle size side is 50%.₅₀) Is in the range of 1 to 10 μm, and the particle content P is 0.1 μm or more and less than 3 μm.₁(%) And the content P of particles having a particle size of 3 μm to 10 μm₂Ratio P to (%)_r= P₂/ P₁A talc with a value of at least 1.1 is used.
  Talc is a hydrous silicate mineral of magnesium, and the composition formula is generally Mg₃Si₄O₁₀(OH)₂It is represented by Examples of such talc include “Simgon”, “Talc MS”, “MICRO ACE SG-95”, “MICRO ACE P-8”, “MICRO ACE P-6”, “MICRO ACE P-4”, “MICRO”. "ACE P-3", "MICRO ACE P-2", "MICRO ACE L-1", "MICRO ACE K-1", "MICRO ACE LG", "MICRO ACE S-3", "NANO ACE D" -1000 "(trade name, manufactured by Nippon Talc)," P talc "," PH talc "," PS talc "," TTK talc "," TT talc "," T talc "," ST talc "," "Hightron", "Hightron A", "Microlite", "Hilac", "Himicron HE5" (trade name, manufactured by Takehara Chemical Industry Co., Ltd.) Commercially available products of the like.
  The volume-based particle size distribution of talc (B) can be measured by a laser diffraction / scattering method. In this specification, the volume-based particle size distribution of talc (B) is measured using a laser diffraction / scattering particle size distribution measuring device “Microtrack NT3300” (trade name, manufactured by Nikkiso Co., Ltd.). At that time, water was used as a dispersion medium, and the sample concentration was adjusted to be within a predetermined transmittance range set in the apparatus.
  From the volume-based particle size distribution measured as described above, the particle size (D₅₀) Can be calculated. In talc (B), from the viewpoint of smoothness and chipping resistance of the resulting coating film, the particle size (D₅₀) Is preferably in the range of 1 to 10 μm, particularly 2 to 9 μm, more particularly 3 to 8 μm.
  In addition, talc (B) has a content P of particles having a particle size of 0.1 μm or more and less than 3 μm in a volume-based particle size distribution from the viewpoint of the smoothness and chipping resistance of the resulting coating film.₁(%) And the content P of particles having a particle size of 3 μm to 10 μm₂Ratio P to (%)_r= P₂/ P₁Is preferably in the range of at least 1.1, in particular 1.3 to 20, more particularly 1.5 to 10, and even more particularly 2 to 5.
  Particle size (D) where the cumulative particle size distribution from talc is 50% from the small particle size side₅₀) And content P₁And content P₂Ratio P_rAs a method for adjusting the amount of the talc to fall within the above specific range, for example, a method of adjusting a pulverization time when talc is pulverized, a method of adjusting a dispersion time when talc is dispersed in a paint solvent, etc. Is mentioned.
Resin containing hydroxyl group and phosphate group (C)
  The resin (C) containing a hydroxyl group and a phosphate group used in the coating composition of the present invention is a resin having at least one hydroxyl group and at least one phosphate group in one molecule. Examples of the type include acrylic resin, polyester resin, and polyurethane resin.
  The above-mentioned resin (C) containing a hydroxyl group and a phosphate group generally has a hydroxyl value within the range of 15 to 200 mgKOH / g, particularly 20 to 140 mgKOH / g, more particularly 30 to 100 mgKOH / g. The resin (C) preferably has an acid value within a range of generally 10 to 200 mgKOH / g, particularly 40 to 170 mgKOH / g, more particularly 70 to 150 mgKOH / g. Furthermore, it is preferred that the resin (C) generally has a number average molecular weight in the range of 2,000 to 100,000, particularly 4,000 to 50,000, more particularly 8,000 to 30,000.
  Examples of the resin (C) containing a hydroxyl group and a phosphate group include 1 to 50 parts by mass of a hydroxyl group-containing polymerizable unsaturated monomer (c-1) described below, a phosphate group-containing polymerizable unsaturated monomer (c-). 2) The copolymer (C ') obtained by copolymerizing 1-70 mass parts and other polymerizable unsaturated monomers (c-3) 0-98 mass parts is suitable.
Hydroxyl-containing polymerizable unsaturated monomer (c-1)
  The hydroxyl group-containing polymerizable unsaturated monomer (c-1) is a compound having at least one hydroxyl group and polymerizable unsaturated bond in one molecule, and specifically, for example, 2-hydroxyethyl (meth) acrylate. -Monoester of (meth) acrylic acid such as 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and a dihydric alcohol having 2 to 8 carbon atoms Ε-caprolactone modified products of these monoester compounds; N-hydroxymethyl (meth) acrylamide; allyl alcohol; (meth) acrylate having a polyoxyethylene chain having a hydroxyl group at the molecular end. These can be used alone or in combination of two or more.
Phosphoric acid group-containing polymerizable unsaturated monomer (c-2)
  The phosphoric acid group-containing polymerizable unsaturated monomer (c-2) is a compound having at least one phosphoric acid group and a polymerizable unsaturated bond in one molecule. Specifically, for example, the following general formula ( 1)

[Wherein R¹Represents a hydrogen atom or a methyl group, X represents —O— or —NH—, R²Represents a divalent organic group having 1 to 30 carbon atoms]
The phosphate group containing polymerizable unsaturated monomer represented by these can be mentioned.
  In the above general formula (1), X is preferably —O—. R²It is preferable that it is a C1-C30 alkylene group which may have an ether bond, an ester bond, or a carbonate bond as a C1-C30 organic group shown by these.
  Examples of the phosphoric acid group-containing polymerizable unsaturated monomer (c-2) include alkylene-modified phosphoric acid group-containing polymerizable unsaturated monomer (c-2-1) and oxyalkylene-modified phosphoric acid group-containing polymerization described below. Unsaturated monomer (c-2-2), polyester-modified phosphate group-containing polymerizable unsaturated monomer (c-2-3), polycarbonate-modified phosphate group-containing polymerizable unsaturated monomer (c-2-4), etc. Is preferably used. These can be used alone or in combination of two or more.
  The alkylene-modified phosphate group-containing polymerizable unsaturated monomer (c-2-1) is represented by the following general formula (2):

[Wherein R¹Has the same meaning as above, R³Represents an alkylene group having 1 to 6 carbon atoms]
It is a monomer represented by.
  In the above formula (2), the alkylene group represented by R3 may be either linear or branched. Also. The alkylene group preferably has 2 to 4 carbon atoms, and more preferably 2 or 3 carbon atoms.
  Specific examples of the alkylene-modified phosphate group-containing polymerizable unsaturated monomer (c-2-1) include acid phosphooxyethyl (meth) acrylate, acid phosphooxypropyl (meth) acrylate, and acid phosphooxy. Examples thereof include butyl (meth) acrylate and acid phosphooxyhexyl (meth) acrylate. These can be used alone or in combination of two or more. Of these, acid phosphooxyethyl (meth) acrylate is particularly preferred.
  The oxyalkylene-modified phosphate group-containing polymerizable unsaturated monomer (c-2-2) is represented by the following general formula (3):

[Wherein R¹Has the same meaning as above, R⁴Represents an alkylene group having 1 to 10 carbon atoms, p represents an integer of 3 to 30, and a plurality of R⁴May be the same or different from each other]
It is a monomer represented by.
  In the above formula (3), the alkylene group represented by R4 may be either linear or branched. Also. The alkylene group preferably has 2 to 4 carbon atoms, and more preferably 2 or 3 carbon atoms. p is preferably an integer of 4 to 20, and more preferably an integer of 5 to 15.
  Specific examples of the oxyalkylene-modified phosphoric acid group-containing polymerizable unsaturated monomer (c-2-2) include, for example, acid phosphooxytetra (oxyethylene) glycol mono (meth) acrylate, acid phosphooxypenta (oxy) Ethylene) glycol mono (meth) acrylate, acid phosphooxypenta (oxypropylene) glycol mono (meth) acrylate, acid phosphooxyhexa (oxypropylene) glycol mono (meth) acrylate, and the like. These can be used alone or in combination of two or more.
  The oxyalkylene-modified phosphoric acid group-containing polymerizable unsaturated monomer (c-2-2) is, for example, a (meth) acrylic acid modified with an alkylene oxide according to a conventional method, and known phosphorous pentoxide, phosphorus oxychloride and the like. It can be easily synthesized by allowing a phosphorylating agent to act and then hydrolyzing. Examples of the alkylene oxide used for modification include ethylene oxide, propylene oxide, butylene oxide, and the like. Among these, ethylene oxide and / or propylene oxide are preferable, and propylene oxide is more preferable.
  The polyester-modified phosphoric acid group-containing polymerizable unsaturated monomer (c-2-3) is represented by the following general formula (4).

[Wherein R¹And X have the same meaning as above, and R⁵Represents an alkylene group having 1 to 6 carbon atoms, and R⁶And R⁷Each independently represents an alkylene group having 1 to 10 carbon atoms, q represents an integer of 1 to 30, and when q is 2 or more, a plurality of R⁶May be the same as or different from each other, r represents an integer of 0 to 30, and when r is 2 or more, a plurality of R⁷May be the same or different from each other]
It is a monomer represented by.
  In the above formula (4), the alkylene group represented by R5 may be either linear or branched. The alkylene group preferably has 2 to 4 carbon atoms, and more preferably 2 or 3 carbon atoms. The alkylene group represented by R6 may be linear or branched. The alkylene group preferably has 2 to 6 carbon atoms, and more preferably 4 to 6 carbon atoms. The alkylene group represented by R7 may be either linear or branched. Also. The alkylene group preferably has 2 to 4 carbon atoms, and more preferably 2 or 3 carbon atoms. q is preferably an integer of 1 to 20, and more preferably an integer of 1 to 10. r is preferably an integer of 0 to 20, and more preferably an integer of 0 to 10.
  Polyester-modified phosphoric acid group-containing polymerizable unsaturated monomer (c-2-3) is prepared by, for example, modifying a hydroxyl group-containing (meth) acrylate with a cyclic ester and / or alkylene oxide according to a conventional method, After acting, it can be easily synthesized by hydrolysis.
  Examples of the cyclic ester include lactones having 3 to 11 carbon atoms such as β-propiolactone, γ-butyrolactone, δ-valerolactone, and ε-caprolactone. These can be used alone or in combination of two or more. Of these, ε-caprolactone is preferably used. As the phosphorylating agent, those known per se, for example, phosphorus pentoxide, phosphorus oxychloride and the like can be used.
  The polycarbonate-modified phosphate group-containing polymerizable unsaturated monomer (c-2-4) is represented by the following general formula (5).

[Wherein R¹And X have the same meaning as above, and R⁸Represents an alkylene group having 1 to 6 carbon atoms, and R⁹And R¹⁰Independently represent an alkylene group having 1 to 10 carbon atoms, s represents an integer of 1 to 30, and when s is 2 or more, a plurality of R⁹May be the same as or different from each other, t represents an integer of 0 to 30, and when t is 2 or more, a plurality of R¹⁰May be the same or different from each other]
It is a monomer represented by.
  In the above formula (5), R⁸The alkylene group represented by may be linear or branched. The alkylene group preferably has 2 to 4 carbon atoms, and more preferably 2 or 3 carbon atoms. R⁹The alkylene group represented by may be linear or branched. The alkylene group preferably has 2 to 6 carbon atoms, and more preferably 2 to 4 carbon atoms. R¹⁰The alkylene group represented by may be linear or branched. The alkylene group preferably has 2 to 4 carbon atoms, and more preferably 2 or 3 carbon atoms. s is preferably an integer of 1 to 20, and more preferably an integer of 1 to 10. t is preferably an integer of 0 to 20, and more preferably an integer of 0 to 10.
  Polycarbonate-modified phosphoric acid group-containing polymerizable unsaturated monomer (c-2-4) is prepared by, for example, modifying a hydroxyl group-containing (meth) acrylate with a cyclic carbonate and / or alkylene oxide according to a conventional method, After acting, it can be easily synthesized by hydrolysis.
  Examples of the cyclic carbonate include 1,3-dioxolan-2-one, 1,3-dioxan-2-one, 1,3-dioxepan-2-one, and the like. These can be used alone or in combination of two or more. As the phosphorylating agent, those known per se, for example, phosphorus pentoxide, phosphorus oxychloride and the like can be used.
Other polymerizable unsaturated monomer (c-3)
  The other polymerizable unsaturated monomer (c-3) may be copolymerized with the hydroxyl group-containing polymerizable unsaturated monomer (c-1) and the phosphate group-containing polymerizable unsaturated monomer (c-2) ( It is a polymerizable unsaturated monomer other than (c-1) and (c-2). The monomer (c-3) can be appropriately selected and used depending on the properties desired for the resin (C) containing a hydroxyl group and a phosphate group. Specific examples of the monomer (c-3) include those described in the following (i) to (xviii). These can be used alone or in combination of two or more.
(I) alkyl or cycloalkyl (meth) acrylate: for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, tridecyl (meth) Acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) Acrylate, cyclododecyl (meth) acrylate, tricyclodecanyl (meth) acrylate.
(Ii) Polymerizable unsaturated monomer having an isobornyl group: for example, isobornyl (meth) acrylate.
(Iii) Polymerizable unsaturated monomer having an adamantyl group: for example, adamantyl (meth) acrylate and the like.
(Iv) Polymerizable unsaturated monomer having a tricyclodecenyl group: for example, tricyclodecenyl (meth) acrylate.
(V) Aromatic ring-containing polymerizable unsaturated monomer: for example, benzyl (meth) acrylate, styrene, α-methylstyrene, vinyltoluene and the like.
(Vi) Polymerizable unsaturated monomer having an alkoxysilyl group: for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, γ- (meth) acryloyloxypropyltrimethoxysilane, γ- ( (Meth) acryloyloxypropyltriethoxysilane and the like.
(Vii) Polymerizable unsaturated monomer having a fluorinated alkyl group: for example, perfluoroalkyl (meth) acrylate such as perfluorobutylethyl (meth) acrylate and perfluorooctylethyl (meth) acrylate; fluoroolefin and the like.
(Viii) A polymerizable unsaturated monomer having a photopolymerizable functional group such as a maleimide group.
(Ix) Vinyl compound: For example, N-vinylpyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate, vinyl acetate and the like.
(X) Carboxy group-containing polymerizable unsaturated monomer: For example, (meth) acrylic acid, maleic acid, crotonic acid, β-carboxyethyl acrylate, and the like.
(Xi) Nitrogen-containing polymerizable unsaturated monomer: for example, (meth) acrylonitrile, (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N- Dimethylaminopropyl (meth) acrylamide, methylenebis (meth) acrylamide, ethylenebis (meth) acrylamide, 2- (methacryloyloxy) ethyltrimethylammonium chloride, an adduct of glycidyl (meth) acrylate and amines, and the like.
(Xii) A polymerizable unsaturated monomer having two or more polymerizable unsaturated groups in one molecule: for example, allyl (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and the like.
(Xiii) Epoxy group-containing polymerizable unsaturated monomer: for example, glycidyl (meth) acrylate, β-methylglycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 3,4-epoxycyclohexylethyl (meth) ) Acrylate, 3,4-epoxycyclohexylpropyl (meth) acrylate, allyl glycidyl ether and the like.
(Xiv) (meth) acrylate having a polyoxyethylene chain whose molecular end is an alkoxy group.
(Xv) polymerizable unsaturated monomer having a sulfonic acid group: for example, 2-acrylamido-2-methylpropanesulfonic acid, 2-sulfoethyl (meth) acrylate, allylsulfonic acid, 4-styrenesulfonic acid, etc .; Sodium salt, ammonium salt and the like.
(Xvi) polymerizable unsaturated monomer having an ultraviolet absorbing functional group: for example, 2-hydroxy-4- (3-methacryloyloxy-2-hydroxypropoxy) benzophenone, 2-hydroxy-4- (3-acryloyloxy-2) -Hydroxypropoxy) benzophenone, 2,2'-dihydroxy-4- (3-methacryloyloxy-2-hydroxypropoxy) benzophenone, 2,2'-dihydroxy-4- (3-acryloyloxy-2-hydroxypropoxy) benzophenone, 2- (2′-hydroxy-5′-methacryloyloxyethylphenyl) -2H-benzotriazole and the like.
(Xvii) Light-stable polymerizable unsaturated monomer: for example, 4- (meth) acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4- (meth) acryloyloxy-2,2,6, 6-tetramethylpiperidine, 4-cyano-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 1- (meth) acryloyl-4- (meth) acryloylamino-2,2,6 , 6-tetramethylpiperidine, 1- (meth) acryloyl-4-cyano-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6 6-tetramethylpiperidine, 4-crotonoylamino-2,2,6,6-tetramethylpiperidine, 1-crotonoyl-4-crotonoyloxy-2, , 6,6-tetramethylpiperidine and the like.
(Xviii) polymerizable unsaturated monomer having a carbonyl group: for example, acrolein, diacetone acrylamide, diacetone methacrylamide, acetoacetoxyethyl methacrylate, formylstyrol, vinyl alkyl ketone having 4 to 7 carbon atoms (for example, vinyl Methyl ketone, vinyl ethyl ketone, vinyl butyl ketone) and the like.
  From the viewpoint of the water resistance of the resulting coating film, the other polymerizable unsaturated monomer (c-3) preferably contains a hydrophobic polymerizable unsaturated monomer as at least a part of its components.
  The hydrophobic polymerizable unsaturated monomer includes a polymerizable unsaturated monomer having a linear, branched or cyclic saturated or unsaturated hydrocarbon group having 6 or more carbon atoms, and a hydroxyl group-containing polymerizable unsaturated monomer. Monomers having hydrophilic groups such as are excluded. Examples of such hydrophobic polymerizable unsaturated monomers include n-hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, tridecyl (meth) acrylate, and lauryl. Alkyl such as (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, cyclododecyl (meth) acrylate or the like Cycloalkyl (meth) acrylate; polymerizable unsaturated monomer having an isobornyl group such as isobornyl (meth) acrylate; heavy having an adamantyl group such as adamantyl (meth) acrylate Sex unsaturated monomer; benzyl (meth) acrylate, styrene, alpha-methyl styrene, can be mentioned aromatic ring-containing polymerizable unsaturated monomers such as vinyl toluene. These can be used alone or in combination of two or more. From the viewpoint of improving the water resistance of the resulting coating film, it is particularly preferable to use an aromatic ring-containing polymerizable unsaturated monomer, and it is more preferable to use styrene.
  The hydrophobic polymerizable unsaturated monomer is composed of a hydroxyl group-containing polymerizable unsaturated monomer (c-1), a phosphoric acid group-containing polymerizable unsaturated monomer (c-2) and other polymerizable unsaturated monomers (c-3). It is suitable to use in the range of generally 2 to 80% by mass, particularly 10 to 60% by mass, more particularly 15 to 40% by mass, based on the total amount.
  In the copolymer (C ′), the hydroxyl group-containing polymerizable unsaturated monomer (c-1), the phosphoric acid group-containing polymerizable unsaturated monomer (c-2), and other polymerizable unsaturated monomers (c-3). The use ratio can be within the following range based on the total amount of the monomers (c-1) to (c-3).
Hydroxyl group-containing polymerizable unsaturated monomer (c-1): 1 to 50% by mass, preferred
                                          Or 5-40% by mass
                                          More preferably, 10
                                          30% by mass,
Phosphoric acid group-containing polymerizable unsaturated monomer (c-2): 1 to 70% by mass, preferred
                                            Or 10-55 quality
                                            % By weight, more preferred
                                            Is 20 to 45% by mass,
Other polymerizable unsaturated monomer (c-3): 0 to 98% by mass, preferably
                                        5 to 85% by mass,
                                        Preferably 25-70 quality
                                        amount%.
  The copolymerization of the hydroxyl group-containing polymerizable unsaturated monomer (c-1), the phosphoric acid group-containing polymerizable unsaturated monomer (c-2) and the other polymerizable unsaturated monomer (c-3) is, for example, in an organic solvent. Can be carried out by a method known per se, such as a solution polymerization method in E. coli and an emulsion polymerization method in an aqueous medium. Of these, the solution polymerization method is preferred.
  In the case of the solution polymerization method, for example, a hydroxyl group-containing polymerizable unsaturated monomer (c-1), a phosphate group-containing polymerizable unsaturated monomer (c-2), and other polymerizable unsaturated monomers (c-3) The copolymer (C ′) is prepared by dissolving or dispersing the mixture with the radical polymerization initiator in an organic solvent and copolymerizing by heating with stirring at a temperature of about 80 to about 200 ° C. for about 1 to 10 hours. ) Can be obtained.
  Examples of the organic solvent that can be used in the copolymerization reaction include hydrocarbon solvents such as heptane, toluene, xylene, octane, mineral spirits; ethyl acetate, n-butyl acetate, isobutyl acetate, ethylene glycol monomethyl ether acetate, diethylene glycol Ester solvents such as monobutyl ether acetate; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone and cyclohexanone; alcohol solvents such as methanol, ethanol, isopropanol, n-butanol, sec-butanol and isobutanol; n-butyl ether , Dioxane, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene Ether solvents such as recall monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether; N, N-dimethylacetamide, N, N-dimethylformamide, N-methyl Amide solvents such as 2-pyrrolidone and N, N-dimethyl-β-methoxypropionamide; Urea solvents such as 1,3-dimethyl-2-imidazolidinone; Sulfoxide solvents such as dimethyl sulfoxide; Tetramethylene Sulfone solvents such as sulfone; aromatic petroleum solvents such as “Swazole 310”, “Swazole 1000”, “Swazole 1500” (all are trade names) manufactured by Maruzen Petrochemical Co., Ltd. The These organic solvents can be used alone or in combination of two or more. It is preferable that the usage-amount of the organic solvent in solution polymerization is 400 mass parts or less normally per 100 mass parts of total amounts of monomer (c-1)-(c-3).
  Examples of the radical polymerization initiator include ketone peroxides such as cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, and methylcyclohexanone peroxide; 1,1-bis (tert-butylperoxy) -3 Peroxyketals such as 1,3,5-trimethylcyclohexane, 1,1-bis (tert-butylperoxy) cyclohexane, n-butyl-4,4-bis (tert-butylperoxy) valerate; cumene hydroperoxide Hydroperoxides such as 2,5-dimethylhexane-2,5-dihydroperoxide; 1,3-bis (tert-butylperoxy-m-isopropyl) benzene, 2,5-dimethyl-2,5 -Di (tert-butylperoxy) Dialkyl peroxides such as xane, diisopropylbenzene peroxide, tert-butyl cumyl peroxide; diacyl peroxides such as decanoyl peroxide, lauroyl peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide; bis ( peroxycarbonates such as tert-butylcyclohexyl) peroxydicarbonate; organic peroxides such as peroxyesters such as tert-butylperoxybenzoate and 2,5-dimethyl-2,5-di (benzoylperoxy) hexane. Oxide polymerization initiator: 2,2′-azobisisobutyronitrile, 1,1-azobis (cyclohexane-1-carbonitrile), azocumene 2,2′-azobismethylvaleronitrile, 4,4′- A Bis (4-cyanovaleric acid) azo-based polymerization initiator such as and the like. Although the usage-amount of these radical polymerization initiators is not specifically limited, About 0.1 to about 15 mass parts normally per 100 mass parts of total amounts of monomer (c-1)-(c-3). Is preferably within the range of about 0.3 to about 10 parts by mass.
  In the above polymerization reaction, the order of addition of the monomer component and the polymerization initiator is not particularly limited, but the polymerization initiator is used at the initial stage of polymerization from the viewpoint of easy temperature control in the polymerization reaction and suppression of formation of a defective cross-linked gel. Rather than batch charging, it is preferable to divide and drop in several portions from the initial polymerization to the late polymerization.
  The copolymer (C ′) thus obtained generally has a hydroxyl value in the range of 15 to 200 mgKOH / g, particularly 20 to 140 mgKOH / g, more particularly 30 to 100 mgKOH / g. The copolymer (C ') preferably has an acid value within the range of generally 10 to 200 mgKOH / g, particularly 40 to 170 mgKOH / g, more particularly 60 to 150 mgKOH / g. Further, the copolymer (C ′) generally has a number average molecular weight in the range of 2,000 to 100,000, especially 4,000 to 50,000, more particularly 8,000 to 30,000. It is.
Basecoat paint composition
  The base coat coating composition of the present invention comprises the above-described film-forming resin component (A), talc (B) and resin (C) containing a hydroxyl group and a phosphate group in a solvent by a usual coating means. It can be prepared by mixing uniformly. As the solvent, an organic solvent or an aqueous solvent can be used. As the aqueous solvent, deionized water or a mixture of deionized water and a hydrophilic organic solvent can be used. Examples of the hydrophilic organic solvent include propylene glycol monomethyl ether.
  In mixing, the talc (B) and the resin (C) containing a hydroxyl group and a phosphate group are mixed in advance from the viewpoint of smoothness, sharpness, adhesion, chipping resistance, and the like of the resulting coating film. It is preferable to prepare a pigment dispersion and mix and disperse the pigment dispersion together with the film-forming resin component (A) in an organic solvent or an aqueous medium.
  The content of the film-forming resin component (A), talc (B) and the resin (C) containing a hydroxyl group and a phosphoric acid group in the base coat coating composition of the present invention is as follows. It is preferable to be within the following range based on 100 parts by mass of the total resin solid content of the resin (C) containing a phosphate group.
Film-forming resin component (A): 50 to 99.5 parts by mass, preferably 75 to
                          99 parts by weight, more preferably 85-98
                          Parts by mass,
Talc (B): 2 to 50 parts by mass, preferably 5 to 30 parts by mass, more preferably
              It is preferably 6.5 to 25 parts by mass, more preferably 8
              ~ 20 parts by mass,
Resin (C) containing hydroxyl group and phosphate group: 0.5 to 50 parts by mass, preferred
                                        1-25 parts by weight
                                        More preferably 2-15
                                        Parts by mass.
  By using the base coat coating composition of the present invention, a coating film having excellent adhesion and chipping resistance and excellent smoothness and sharpness required for top coating can be formed. The reason for this is that the talc (B) in the paint has a particle size (D) where the cumulative particle size distribution from the small particle size side is 50%.₅₀) Is in the range of 1 to 10 μm and contains talc having a relatively small particle size as a main component, while the content P of particles having a particle size of 0.1 μm or more and less than 3 μm.₁(%) And the content P of particles having a particle size of 3 μm to 10 μm₂Ratio P to (%)_r= P₂/ P₁Is 1.1 or more, contains more particles with a particle size of 3 μm or more and 10 μm or less than particles with a particle size of 0.1 μm or more and less than 3 μm, and is not excessively reduced in particle size, thereby impairing chipping resistance It is speculated that a coating film having excellent smoothness and sharpness can be formed. Furthermore, since the phosphate group in the resin (C) containing a hydroxyl group and a phosphate group interacts with talc (B) and talc (B) is uniformly dispersed in the coating film, It is surmised that smoothness, sharpness, and coating film strength are improved, and as a result, a coating film excellent in smoothness, sharpness, adhesion, and chipping resistance is formed.
  The coating composition of the present invention preferably further contains a hydrophobic solvent (D) from the viewpoint of improving the smoothness of the resulting coating film.
  As the hydrophobic solvent (D), it is desirable to use an organic solvent having a dissolution mass in 100 g of water at 20 ° C. of 10 g or less, preferably 5 g or less, more preferably 1 g or less. Examples of the organic solvent include hydrocarbon solvents such as rubber volatile oil, mineral spirit, toluene, xylene, and solvent naphtha; 1-hexanol, 1-octanol, 2-octanol, 2-ethyl-1-hexanol, 1-hexanol, Decanol, benzyl alcohol, ethylene glycol mono 2-ethylhexyl ether, propylene glycol mono n-butyl ether, dipropylene glycol mono n-butyl ether, tripropylene glycol mono n-butyl ether, propylene glycol mono 2-ethylhexyl ether, propylene glycol monophenyl ether, etc. Alcohol solvents; ester solvents such as n-butyl acetate, isobutyl acetate, isoamyl acetate, methyl amyl acetate, and ethylene glycol monobutyl ether Methyl isobutyl ketone, cyclohexanone, ethyl n- amyl ketone solvents such as diisobutyl ketone. These can be used alone or in combination of two or more.
  As the hydrophobic solvent (D), an alcohol-based hydrophobic solvent is preferably used from the viewpoint of the smoothness of the resulting coating film. Among these, alcohol-based hydrophobic solvents having 7 to 14 carbon atoms are preferable, such as 1-octanol, 2-octanol, 2-ethyl-1-hexanol, ethylene glycol mono-2-ethylhexyl ether, propylene glycol mono n-butyl ether, dipropylene. More preferred is at least one alcohol-based hydrophobic solvent selected from the group consisting of glycol mono n-butyl ether.
  When the coating composition of the present invention contains the hydrophobic solvent (D), the content of the hydrophobic solvent (D) is the film-forming resin component (A) and the resin (C) containing a hydroxyl group and a phosphate group. The total resin solid content is usually within the range of 10 to 100 parts by weight, particularly 20 to 80 parts by weight, and more particularly 30 to 60 parts by weight.
  Moreover, the coating composition of this invention can contain a luster pigment (E). The glitter pigment (E) is a pigment used for imparting a glittering glitter or light interference pattern to the coating film. Specifically, for example, non-leafing type or leafing type aluminum (evaporated aluminum) At least one selected from copper, zinc, brass, nickel, glass flakes, aluminum oxide, mica, aluminum oxide coated with titanium oxide or iron oxide, mica coated with titanium oxide or iron oxide, etc. Pigments can be used. Among these, it is particularly preferable to use an aluminum pigment.
  The metallic pigment is preferably in the form of flakes. These metallic pigments have a longitudinal dimension of 1 to 100 μm, particularly 5 to 40 μm, and a thickness of 0.001 to 5 μm, particularly 0.01. Those in the range of ˜2 μm are suitable.
  The glitter pigment (E) is usually 1 to 50 parts by mass, particularly 5 to 35 parts per 100 parts by mass of the total resin solid content of the film-forming resin component (A) and the resin (C) containing a hydroxyl group and a phosphate group. It is suitable to use within a range of parts by mass, more particularly 8 to 20 parts by mass.
  The coating composition of the present invention may further include a color pigment, extender pigment, thickener, curing catalyst, ultraviolet absorber, light stabilizer, antifoaming agent, plasticizer, organic solvent, surface conditioner, sedimentation, if necessary. Ordinary paint additives such as inhibitors can be used alone or in combination of two or more.
  Examples of the color pigment include titanium oxide, zinc white, carbon black, molybdenum red, Prussian blue, cobalt blue, azo pigment, phthalocyanine pigment, quinacridone pigment, isoindoline pigment, selenium pigment, and perylene pigment. , Dioxazine pigments, diketopyrrolopyrrole pigments, and the like. Examples of the extender pigments include clay, kaolin, barita, barium sulfate, barium carbonate, calcium carbonate, silica, and alumina white.
  The coating composition of the present invention can usually be used as a colored base coat coating composition containing a glitter pigment (E) and / or a colored pigment.
  Examples of the thickener include inorganic thickeners such as silicate, metal silicate, montmorillonite and colloidal alumina; copolymer of (meth) acrylic acid and (meth) acrylic ester, polyacrylic Polyacrylic acid thickeners such as acid soda; having a hydrophilic part and a hydrophobic part in one molecule, and the hydrophobic part is adsorbed on the surface of pigments and emulsion particles in the paint in an aqueous medium , An associative thickener that effectively exhibits a thickening action by the hydrophobic parts being associated with each other; a fibrous derivative-based thickener such as carboxymethylcellulose, methylcellulose, hydroxyethylcellulose; casein, sodium caseinate, Protein thickeners such as ammonium caseinate; Alginate thickeners such as sodium alginate; Polyvinyl alcohol, Polyvinylpyrrolidone Polyvinyl thickeners such as polyvinyl benzyl ether copolymer; polyether thickeners such as pluronic polyether, polyether dialkyl ester, polyether dialkyl ether, and polyether epoxy modified product; vinyl methyl ether-maleic anhydride copolymer Examples thereof include a maleic anhydride copolymer thickener such as a partial ester of a polymer; a polyamide thickener such as a polyamideamine salt. These thickeners can be used alone or in combination of two or more. As the thickener, a polyacrylic acid thickener and / or an associative thickener is particularly suitable. Commercially available products can be used as the polyacrylic acid thickener, for example, “Primal ASE-60”, “Primal TT-615”, “Primal RM-5” (above, manufactured by Rohm and Haas) Commercially available products such as “SN thickener 613”, “SN thickener 618”, “SN thickener 630”, “SN thickener 634”, “SN thickener 636” (all are trade names) manufactured by San Nopco. Goods. Moreover, as said associative thickener, a commercial item can be used, for example, "UH-420", "UH-450", "UH-462", "UH-472" made by ADEKA, “UH-540”, “UH-752”, “UH-756VF”, “UH-814N” (all are trade names); “Primal RM-8W”, “Primal RM-825” manufactured by Rohm and Haas. “Primal RM-2020NPR”, “Primal RM-12W”, “Primal SCT-275” (all are trade names); “SN thickener 612”, “SN thickener 621N”, “SN thickener” manufactured by San Nopco. Commercial products such as “625N”, “SN thickener 627N”, “SN thickener 660T” (all are trade names).
  When the coating composition of the present invention contains the above thickener, the content of the thickener is the total resin solids of the film-forming resin component (A) and the resin (C) containing a hydroxyl group and a phosphate group. It is suitable that it is usually in the range of 0.01 to 10 parts by mass, particularly 0.05 to 3 parts by mass, more preferably 0.1 to 2 parts by mass per 100 parts by mass of the minute.
  The coating composition of the present invention generally has a solid content in the range of 5 to 50% by mass, particularly 15 to 40% by mass, and more particularly 20 to 30% by mass.
Painting
  The coating composition of the present invention can form a coating film having excellent smoothness, sharpness, adhesion and chipping resistance by coating on various objects.
  The coating object to which the coating composition of the present invention can be applied is not particularly limited, and examples thereof include an outer plate part of an automobile body such as a passenger car, a truck, a motorcycle, and a bus; an automobile part; a mobile phone and an audio device. And the like, and the like. Especially, the outer-plate part of a motor vehicle body and a motor vehicle part are preferable.
  In addition, the material of the object to which the coating composition of the present invention can be applied is not particularly limited, for example, iron, aluminum, brass, copper plate, stainless steel plate, tin plate, galvanized steel plate, alloying Metal materials such as zinc (Zn-Al, Zn-Ni, Zn-Fe, etc.) plated steel sheets; polyethylene resin, polypropylene resin, acrylonitrile-butadiene-styrene (ABS) resin, polyamide resin, acrylic resin, vinylidene chloride resin, polycarbonate resin Resin such as polyurethane resin and epoxy resin and various plastic materials such as FRP; inorganic materials such as glass, cement and concrete; wood; fiber materials (paper, cloth, etc.), among others, metal Materials and plastic materials are preferred.
  The object to be coated may be one in which an undercoat film such as an electrodeposition film is formed on a substrate such as the metal material. In addition, an undercoat coating film and an intermediate coating film may be sequentially formed on the substrate. When the substrate is a metal material, it may have been subjected to surface treatment such as phosphate treatment, chromate treatment, complex oxide treatment in advance before forming an undercoat on the substrate. Good.
  The coating method of the coating composition of the present invention is not particularly limited, and examples thereof include air spray coating, airless spray coating, rotary atomization coating, and curtain coat coating. A wet coating film can be formed by these coating methods. Of these, methods such as air spray coating and rotary atomization coating are preferred. When applying, electrostatic application may be performed as necessary.
  The coating amount of the coating composition of the present invention is usually 2 to 40 μm, preferably 5 to 30 μm, and more preferably 8 to 18 μm as a cured film thickness.
  Curing of the wet coating film can be performed by heating the coating composition of the present invention on the object to be coated. Heating can be performed by a known heating means, and for example, a drying furnace such as a hot air furnace, an electric furnace, an infrared induction heating furnace or the like can be used. The heating temperature can usually be in the range of about 80 to about 180 ° C, preferably about 100 to about 170 ° C, more preferably about 120 to about 160 ° C. In addition, the heating time can be generally in the range of about 10 to about 90 minutes, preferably about 15 to about 60 minutes, more preferably about 20 to about 40 minutes.
  When the coating composition of the present invention is a water-based coating, from the viewpoint of preventing the occurrence of coating film defects such as armpits, the coating film is substantially cured after the coating composition is applied and before the above heat curing is performed. It is preferable to perform preheating, air blowing, etc. under heating conditions that do not. The temperature of the preheating can usually be in the range of about 40 to about 100 ° C, preferably about 50 to about 90 ° C, more preferably about 60 to about 80 ° C. The preheating time can usually be in the range of about 30 seconds to about 20 minutes, preferably about 1 to about 15 minutes, more preferably about 2 to about 10 minutes. The air blowing is usually performed by blowing air heated to a normal temperature or a temperature within a range of about 25 ° C. to about 80 ° C. for about 30 seconds to about 15 minutes on the surface to be coated. it can.
  On the coating film formed by the coating composition of the present invention, a clear coat coating composition known per se can be applied, if necessary. When the clear coat coating composition is applied, the coating film formed by the coating composition of the present invention may be an uncured coating film or a cured coating film. When the coating film formed by the coating composition of the present invention is an uncured coating film, the coating film of the coating composition of the present invention and the coating film of the clear coating coating composition are applied after the clear coating coating composition is applied. It can be cured by heating at the same time.
  The clear coat coating composition can be applied by a method known per se, for example, a method such as air spray coating, airless spray coating, or rotary atomization coating. The coating film thickness of the clear coat coating composition can be generally in the range of 10 to 80 μm, preferably 15 to 60 μm, and more preferably 20 to 50 μm as a cured film thickness.
  The clear coat coating composition can be cured by a known heating means as described above. The heating temperature can usually be in the range of about 80 to about 180 ° C, preferably about 100 to about 170 ° C, more preferably about 120 to about 160 ° C. In addition, the heating time can be generally in the range of about 10 to about 90 minutes, preferably about 15 to about 60 minutes, more preferably about 20 to about 40 minutes.

（注１）「タルク ＭＳ」（商品名、日本タルク社製、タルク粉末）
着色顔料分散液の製造例
製造例１５
製造例１で得た水酸基含有アクリル樹脂溶液（Ａ１−１−１）１８部（樹脂固形分１０部）、「カーボンＭＡ−１００」（商品名、三菱化学社製、カーボンブラック）１０部及び脱イオン水６０部を混合し、２−（ジメチルアミノ）エタノールでｐＨ８．２に調整した後、ペイントシェーカーで３０分間分散して着色顔料分散液を得た。
リン酸基含有重合性不飽和モノマー（ｃ−２）の製造
製造例１６
温度計、サーモスタット、撹拌装置、還流冷却器、空気導入管及び滴下装置を備えた反応容器に、「ＰＬＡＣＣＥＬ ＦＭ２Ｄ」（商品名、ダイセル化学工業（株）製、２−ヒドロキシエチルメタクリレート１モルにε−カプロラクトン２モルを付加したモノマー）３５８部を入れ、反応液中に乾燥空気をバブリングさせながら、５０〜６０℃で五酸化リン６３．９部を少量ずつ加えた。全量添加後、６０℃で５時間熟成し、イオン交換水９．０部を加え、さらに８０℃にて５時間熟成を行い、ポリエステル変性リン酸基含有重合性不飽和モノマー（ｃ−２−３−１）を得た。
製造例１７
温度計、サーモスタット、撹拌装置、還流冷却器、空気導入管及び滴下装置を備えた反応容器に、「ＨＥＭＡＣ１」（商品名、ダイセル化学工業（株）製、ヒドロキシエチルメタクリレート１モルにジメチルトリメチレンカーボネート１モルを付加したモノマー）２６０部を入れ、反応液中に乾燥空気をバブリングさせながら、５０〜６０℃で五酸化リン６３．９部を少量ずつ加えた。全量添加後、６０℃で５時間熟成し、イオン交換水９．０部を加え、さらに８０℃にて５時間熟成を行い、ポリカーボネート変性リン酸基含有重合性不飽和モノマー（ｃ−２−４−１）を得た。
水酸基及びリン酸基を含有する樹脂（Ｃ）の製造例
製造例１８
温度計、サーモスタット、撹拌装置、還流冷却器、窒素導入管及び滴下装置を備えた反応容器にプロピレングリコールモノメチルエーテル１２０部を入れ、１１０℃に加熱し、同温度に保持しつつ、２−ヒドロキシエチルアクリレート１０部、「ライトエステルＰ−１Ｍ」（商品名、共栄社化学社製、アシッドホスホキシエチルメタクリレート、前記一般式（２）において、Ｒ^１がメチル基であり、Ｒ^３がエチレン基である場合の化合物）３０部、スチレン２５部、ラウリルメタクリレート１５部、ｎ−ブチルアクリレート２０部及びｔ−ブチルパーオキシ−２−エチルヘキサノエート３部からなる混合物（Ｉ）１０３部を４時間かけて滴下し、滴下終了後１時間攪拌熟成を行なった。その後、ｔ−ブチルパーオキシ−２−エチルヘキサノエート１部とプロピレングリコールモノメチルエーテル３０部とからなる重合開始剤溶液を１時間かけて滴下し、滴下終了後１時間攪拌熟成して、固形分４０％の水酸基及びリン酸基を含有する樹脂の溶液（Ｃ−１）を得た。得られた水酸基及びリン酸基を含有する樹脂（Ｃ−１）は、水酸基価が４８ｍｇＫＯＨ／ｇ、酸価が１４０ｍｇＫＯＨ／ｇ、数平均分子量が１２，０００であった。
製造例１９〜２２
製造例１８において、混合物（１）に代えて、下記表２に示す配合割合の混合物を使用する以外は、製造例１８と同様にして、固形分４０％の水酸基及びリン酸基を含有する樹脂の溶液（Ｃ−２）〜（Ｃ−５）を得た。下記表２に、水酸基及びリン酸基を含有する樹脂の溶液（Ｃ−１）〜（Ｃ−５）の原料である混合物（部）、水酸基価（ｍｇＫＯＨ／ｇ）、酸価（ｍｇＫＯＨ／ｇ）及び数平均分子量を示す。

（注２）「Ｐｈｏｓｍｅｒ ＰＰ」：商品名、ユニケミカル社製、アシッドホスホキシポリオキシプロピレングリコールモノメタクリレート。前記一般式（３）において、Ｒ^１がメチル基であり、Ｒ^４がプロピレン基であり、ｐが５又は６である場合の化合物。
「ライトエステルＰ−１Ｍ」はアルキレン変性リン酸基含有モノマー（ｃ−２−１）であり、「Ｐｈｏｓｍｅｒ ＰＰ」はオキシアルキレン変性リン酸基含有モノマー（ｃ−２−２）であり、モノマー（ｃ−２−３−１）はポリエステル変性リン酸基含有モノマー（ｃ−２−３）であり、モノマー（ｃ−２−４−１）はポリカーボネート変性リン酸基含有モノマー（ｃ−２−４）である。
スチレン及びラウリルメタクリレートは疎水性重合性不飽和モノマーであり、スチレンは芳香環含有重合性不飽和モノマーである。
リン酸基含有樹脂の製造例
製造例２３
温度計、サーモスタット、撹拌装置、還流冷却器、窒素導入管及び滴下装置を備えた反応容器にプロピレングリコールモノメチルエーテル１２０部を入れ、１１０℃に加熱し、同温度に保持しつつ、「ライトエステルＰ−１Ｍ」（商品名、共栄社化学社製、アシッドホスホキシエチルメタクリレート、前記一般式（２）において、Ｒ^１がメチル基であり、Ｒ^３がエチレン基である場合の化合物）３０部、スチレン２５部、ラウリルメタクリレート１５部、ｎ−ブチルアクリレート３０部及びｔ−ブチルパーオキシ−２−エチルヘキサノエート３部からなる混合物（Ｉ）１０３部を４時間かけて滴下し、滴下終了後１時間攪拌熟成を行なった。その後、ｔ−ブチルパーオキシ−２−エチルヘキサノエート１部とプロピレングリコールモノメチルエーテル３０部とからなる重合開始剤溶液を１時間かけて滴下し、滴下終了後１時間攪拌熟成して、固形分４０％のリン酸基含有樹脂溶液（Ｐ−１）を得た。得られたリン酸基含有樹脂（Ｐ−１）は、水酸基価が０ｍｇＫＯＨ／ｇ、酸価が１４０ｍｇＫＯＨ／ｇ、数平均分子量が８，０００であった。
ベースコート塗料組成物の製造
実施例１
撹拌混合容器内において、製造例４で得たタルク分散液（Ｂ−１）４８部及び製造例１８で得た水酸基及びリン酸基を含有する樹脂の溶液（Ｃ−１）１０部を混合し、タルク混合液を得た。
上記タルク混合液、製造例１で得た水酸基含有アクリル樹脂溶液（Ａ１−１−１）１３部、製造例２で得た水酸基含有アクリル樹脂エマルション（Ａ１−１−２）８３部、製造例３で得た水酸基含有ポリエステル樹脂溶液（Ａ１−２−１）３６部、メラミン樹脂（Ａ２−１）（メチル−ブチル混合エーテル化メラミン樹脂、固形分８０％、重量平均分子量１，４００）３８部及び製造例１５で得た着色顔料分散液４４部を均一に混合し、更に、「プライマルＡＳＥ−６０」（商品名、ロームアンドハース社製、増粘剤）、２−（ジメチルアミノ）エタノール及び脱イオン水を加えて、ｐＨ８．０、塗料固形分２５％、２０℃におけるフォードカップＮｏ．４による粘度が４０秒の水性ベースコート塗料組成物（Ｘ−１）を得た。
実施例２〜１６、比較例１〜４
実施例１において、配合組成を下記表３に示すとおりとする以外は、実施例１と同様にして、ｐＨ８．０、固形分２５％、２０℃におけるフォードカップＮｏ．４による粘度が４０秒である水性ベースコート塗料組成物（Ｘ−２）〜（Ｘ−２０）を得た。

（注３） メラミン樹脂（Ａ２−２）：メチルエーテル化メラミン樹脂、固形分８０％、重量平均分子量８００。
（注４） 「カルボジライトＳＶ−０２」（商品名、日清紡株式会社製、ポリカルボジイミド化合物、固形分４０％）。

（注５） 「ユーコートＵＸ−５０００」（商品名、三洋化成工業株式会社製、ウレタンエマルション、固形分４０％）。
試験用被塗物の作製
リン酸亜鉛処理された冷延鋼板に、熱硬化性エポキシ樹脂系カチオン電着塗料組成物（商品名「エレクロンＧＴ−１０」、関西ペイント社製）を膜厚２０μｍになるように電着塗装し、１７０℃で３０分加熱して硬化させた。次いで、この電着塗膜上に中塗り塗料組成物（商品名「ＴＰ−６５−２」、関西ペイント社製、ポリエステル樹脂・アミノ樹脂系有機溶剤型塗料組成物）を膜厚３５μｍになるように塗装し、１４０℃で３０分間加熱して硬化させた。かくして、鋼板上に電着塗膜及び中塗り塗膜を形成してなる試験用被塗物を作製した。
塗膜形成方法
実施例１７
上記試験用被塗物に、実施例１で得たベースコート塗料組成物（Ｘ−１）を、回転霧化型の静電塗装機を用いて、硬化膜厚１６μｍとなるように静電塗装し、ベースコート塗膜を形成した。３分間放置後、８０℃で３分間プレヒートを行なった後、該未硬化のベースコート塗膜上に「マジクロンＫＩＮＯ−１２１０」（商品名、関西ペイント社製、カルボキシル基含有アクリル樹脂及びエポキシ基含有アクリル樹脂を含む有機溶剤型クリヤーコート塗料組成物）を、回転霧化型の静電塗装機を用いて、硬化膜厚３５μｍとなるように静電塗装し、クリヤーコート塗膜を形成せした。７分間放置後、１４０℃で３０分間加熱して、上記ベースコート塗膜及びクリヤーコート塗膜を同時に硬化させることにより試験塗板を作製した。
実施例１８〜３２、比較例５〜８
実施例１７において、実施例１で得たベースコート塗料組成物（Ｘ−１）を、下記表４に示すベースコート塗料組成物（Ｘ−２）〜（Ｘ−２０）のいずれかに変更する以外は、実施例１７と同様にして試験塗板を作製した。
評価試験
上記実施例１７〜３２及び比較例５〜８で得られた各試験塗板について、下記の試験方法により評価を行なった。評価結果を下記表４に示す。
（試験方法）
平滑性： 「Ｗａｖｅ Ｓｃａｎ ＤＯＩ」（商品名、ＢＹＫ Ｇａｒｄｎｅｒ社製）によって測定されるＷｄ値を用いて評価した。Ｗｄ値が小さいほど塗面の平滑性が高いことを示す。
鮮映性： 「Ｗａｖｅ Ｓｃａｎ ＤＯＩ」によって測定されるＷｂ値を用いて評価した。Ｗｂ値が小さいほど塗面の鮮映性が高いことを示す。
耐水付着性： 試験板を４０℃の温水に２４０時間浸漬し、引き上げ、２０℃で１２時間乾燥した後、試験板の複層塗膜を素地に達するようにカッターで格子状に切り込み、大きさ２ｍｍ×２ｍｍのゴバン目を１００個作る。続いて、その表面に粘着セロハンテープを貼着し、２０℃においてそのテープを急激に剥離した後のゴバン目塗膜の残存状態を調べた。
◎：ゴバン目塗膜が１００個残存し、カッターの切り込みの縁において塗膜の小さなフチカケが生じていない。
○：ゴバン目塗膜が１００個残存するが、カッターの切り込みの縁において塗膜の小さなフチカケが生じている。
△：ゴバン目塗膜が９０〜９９個残存する。
×：ゴバン目塗膜の残存数が８９個以下である。
耐チッピング性： スガ試験機社製の飛石試験機ＪＡ−４００型（チッピング試験装置）の試片保持台に試験板を設置し、−２０℃において、３０ｃｍの距離から０．３９２ＭＰａ（４ｋｇｆ／ｃｍ^２）の圧縮空気により、粒度７号の花崗岩砕石５０ｇを試験板に４５度の角度で衝突させた。その後、得られた試験板を水洗して、乾燥し、塗面に布粘着テープ（ニチバン社製）を貼着して、それを剥離した後、塗膜の傷の発生程度等を目視で観察し、下記の基準により評価した。
（傷の大きさ）
◎：傷が極めて小さい。
○：傷が小さい。
△：傷が大きい。
×：傷が極めて大きい。
（傷の深さ）
◎：電着面及び素地の鋼板面が露出していない。
○：電着面の露出はあるが、素地の鋼板面は露出していない。
△：素地の鋼板面が露出している。
×：電着面及び素地の鋼板面が露出している。

EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited only to these Examples. “Part” and “%” are based on mass.
Production of hydroxyl group-containing resin (A1)
Production of hydroxyl group-containing acrylic resin (A1-1) Production Example 1
A reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, nitrogen inlet tube and dropping device was charged with 35 parts of propylene glycol monopropyl ether, heated to 85 ° C., then 30 parts of methyl methacrylate, 2-ethylhexyl acrylate 20 parts, 29 parts of n-butyl acrylate, 15 parts of 2-hydroxyethyl acrylate, 6 parts of acrylic acid, 15 parts of propylene glycol monopropyl ether and 2.3 parts of 2,2′-azobis (2,4-dimethylvaleronitrile) The mixture was added dropwise over 4 hours, and aged for 1 hour after completion of the addition. Thereafter, a mixture of 10 parts of propylene glycol monopropyl ether and 1 part of 2,2′-azobis (2,4-dimethylvaleronitrile) was added dropwise over 1 hour, followed by aging for 1 hour after completion of the addition. Further, 7.4 parts of diethanolamine was added to obtain a hydroxyl group-containing acrylic resin solution (A1-1-1) having a solid content of 55%. The obtained hydroxyl group-containing acrylic resin had an acid value of 47 mgKOH / g and a hydroxyl value of 72 mgKOH / g.
Production Example 2
A reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser, a nitrogen introduction tube and a dropping device was added to 130 parts of deionized water and “Aqualon KH-10” (trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., polyoxy 0.52 part of ethylene alkyl ether sulfate ester ammonium salt (active ingredient 97%) was charged, mixed with stirring in a nitrogen stream, and heated to 80 ° C. Next, 1% of the total amount of the following monomer emulsion (1) and 5.3 parts of a 6% aqueous ammonium persulfate solution were introduced into the reaction vessel and maintained at 80 ° C. for 15 minutes. Thereafter, the remaining monomer emulsion (1) was dropped into the reaction vessel maintained at the same temperature over 3 hours, and aging was performed for 1 hour after completion of the dropping. Thereafter, the following monomer emulsion (2) was added dropwise over 1 hour, and after aging for 1 hour, the mixture was cooled to 30 ° C. while gradually adding 40 parts of a 5% 2- (dimethylamino) ethanol aqueous solution to the reaction vessel, It is discharged while being filtered through a 100 mesh nylon cloth, and is diluted with deionized water using an average particle diameter of 100 nm (submicron particle size distribution measuring device “COULTER N4 type” (trade name, manufactured by Beckman Coulter, Inc.) at 20 ° C. And a hydroxyl group-containing acrylic resin emulsion (A1-1-2) having a solid content concentration of 30% was obtained. The obtained hydroxyl group-containing acrylic resin had an acid value of 33 mgKOH / g and a hydroxyl value of 25 mgKOH / g.
Monomer emulsion (1): 42 parts of deionized water, 0.72 part of “AQUALON KH-10”, 2.1 parts of methylenebisacrylamide, 2.8 parts of styrene, 16.1 parts of methyl methacrylate, 28 parts of ethyl acrylate and 21 parts of n-butyl acrylate was mixed and stirred to obtain a monomer emulsion (1).
Monomer emulsion (2): 18 parts of deionized water, 0.31 part of “AQUALON KH-10”, 0.03 part of ammonium persulfate, 5.1 part of methacrylic acid, 5.1 part of 2-hydroxyethyl acrylate, styrene 3 Part, 6 parts of methyl methacrylate, 1.8 parts of ethyl acrylate and 9 parts of n-butyl acrylate were mixed and stirred to obtain a monomer emulsion (2).
Production of hydroxyl group-containing polyester resin (A1-2) Production Example 3
In a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser and water separator, 109 parts of trimethylolpropane, 141 parts of 1,6-hexanediol, 126 parts of 1,2-cyclohexanedicarboxylic acid anhydride and adipine After charging 120 parts of acid and raising the temperature from 160 ° C. to 230 ° C. over 3 hours, the resulting condensed water was distilled off with a water separator and subjected to a condensation reaction at 230 ° C. for 4 hours. Subsequently, in order to add a carboxyl group to the obtained condensation reaction product, 38.3 parts of trimellitic anhydride was further added and reacted at 170 ° C. for 30 minutes, and then 2-ethyl-1-hexanol (20 ° C. Was diluted with 100 g of water dissolved in water (0.1 g) to obtain a hydroxyl group-containing polyester resin solution (A1-2-1) having a solid content concentration of 70%. The obtained polyester resin had an acid value of 46 mgKOH / g, a hydroxyl value of 150 mgKOH / g, a solid content concentration of 70%, and a number average molecular weight of 1,400.
Example of production of talc dispersion Production example 4
40 parts of hydroxyl group-containing acrylic resin solution (A1-1-1) obtained in Production Example 1 (22 parts of resin solid content), 30 parts of “MICRO ACE S-3” (trade name, manufactured by Nippon Talc Co., Ltd.) and 70 parts of deionized water was mixed, adjusted to pH 8.0 with 2- (dimethylamino) ethanol, and then dispersed with a paint shaker for 40 minutes to obtain a talc dispersion (B-1). In the obtained talc dispersion, the particle size (D ₅₀ ) at which the cumulative particle size distribution from the small particle size side becomes 50% is 2.1 μm, and the content of particles having a particle size of 0.1 μm or more and less than 3 μm The ratio P _r = P ₂ / P ₁ between P ₁ (%) and the content P ₂ (%) of particles having a particle size of 3 μm or more and 10 μm or less was 1.2.
Production Examples 5-14
In Production Example 4, talc dispersions (B-2) to (B-11) were obtained in the same manner as in Production Example 4 except that the talc and dispersion time were changed to the talc and dispersion time shown in Table 1 below. It was. Table 1 shows the particle size (D ₅₀ ) at which the cumulative particle size distribution from the small particle size side of the talc dispersions (B-1) to (B-11) is 50%, and the particle size is 0.1 μm or more and less than 3 μm. The particle content P ₁ (%), the particle content P ₂ (%) having a particle size of 3 μm or more and 10 μm or less, and the ratio P _r = P ₂ / P ₁ between P ₁ and P ₂ are shown.

(Note 1) “Talc MS” (trade name, manufactured by Nippon Talc Co., Ltd., talc powder)
Production Example of Colored Pigment Dispersion Production Example 15
18 parts of a hydroxyl group-containing acrylic resin solution (A1-1-1) obtained in Production Example 1 (10 parts of resin solid content), 10 parts of “Carbon MA-100” (trade name, manufactured by Mitsubishi Chemical Corporation, carbon black) and desorption 60 parts of ionic water was mixed and adjusted to pH 8.2 with 2- (dimethylamino) ethanol, and then dispersed with a paint shaker for 30 minutes to obtain a colored pigment dispersion.
Production of phosphoric acid group-containing polymerizable unsaturated monomer (c-2) Production Example 16
In a reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser, an air inlet tube and a dropping device, “PLACCEL FM2D” (trade name, manufactured by Daicel Chemical Industries, Ltd., 1 mol of 2-hydroxyethyl methacrylate) -Monomer added with 2 moles of caprolactone) 358 parts were added, and 63.9 parts of phosphorus pentoxide was added little by little at 50-60 ° C while bubbling dry air into the reaction solution. After addition of the entire amount, aging at 60 ° C. for 5 hours, adding 9.0 parts of ion-exchanged water, aging at 80 ° C. for 5 hours, and polyester-modified phosphate group-containing polymerizable unsaturated monomer (c-2-3) -1) was obtained.
Production Example 17
In a reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser, an air introduction tube and a dropping device, “HEMAC1” (trade name, manufactured by Daicel Chemical Industries, Ltd., 1 mol of hydroxyethyl methacrylate and dimethyltrimethylene carbonate) 260 parts of monomer added with 1 mol) was added, and 63.9 parts of phosphorus pentoxide was added little by little at 50-60 ° C. while bubbling dry air into the reaction solution. After addition of the entire amount, aging at 60 ° C. for 5 hours, adding 9.0 parts of ion-exchanged water, and further aging at 80 ° C. for 5 hours, a polycarbonate-modified phosphate group-containing polymerizable unsaturated monomer (c-2-4). -1) was obtained.
Production Example 18 of Resin (C) Containing Hydroxyl Group and Phosphate Group Production Example 18
Into a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, nitrogen inlet tube and dripping device, 120 parts of propylene glycol monomethyl ether was heated to 110 ° C. and maintained at the same temperature while maintaining 2-hydroxyethyl. 10 parts of acrylate, “light ester P-1M” (trade name, manufactured by Kyoeisha Chemical Co., Acid Phosphoxyethyl methacrylate, in the general formula (2), when R ¹ is a methyl group and R ³ is an ethylene group Compound) 30 parts, 25 parts of styrene, 15 parts of lauryl methacrylate, 20 parts of n-butyl acrylate and 3 parts of t-butylperoxy-2-ethylhexanoate (103 parts) are added dropwise over 4 hours. Then, after completion of dropping, the mixture was aged and stirred for 1 hour. Thereafter, a polymerization initiator solution consisting of 1 part of t-butylperoxy-2-ethylhexanoate and 30 parts of propylene glycol monomethyl ether was added dropwise over 1 hour, and after completion of the addition, the mixture was stirred and aged for 1 hour to obtain a solid content. A resin solution (C-1) containing 40% hydroxyl groups and phosphate groups was obtained. The obtained resin (C-1) containing a hydroxyl group and a phosphate group had a hydroxyl value of 48 mgKOH / g, an acid value of 140 mgKOH / g, and a number average molecular weight of 12,000.
Production Examples 19-22
In Production Example 18, a resin containing a hydroxyl group and a phosphate group having a solid content of 40% is used in the same manner as in Production Example 18 except that a mixture having the blending ratio shown in Table 2 below is used instead of the mixture (1). Solutions (C-2) to (C-5) were obtained. In Table 2 below, a mixture (part) which is a raw material of the solution (C-1) to (C-5) of a resin containing a hydroxyl group and a phosphate group, a hydroxyl value (mgKOH / g), an acid value (mgKOH / g) ) And number average molecular weight.

(Note 2) “Phosmer PP”: product name, manufactured by Unichemical Co., Ltd., acid phosphoxypolyoxypropylene glycol monomethacrylate. In the general formula (3), a compound in which R ¹ is a methyl group, R ⁴ is a propylene group, and p is 5 or 6.
“Light ester P-1M” is an alkylene-modified phosphate group-containing monomer (c-2-1), and “Phosmer PP” is an oxyalkylene-modified phosphate group-containing monomer (c-2-2), c-2-3-1) is a polyester-modified phosphate group-containing monomer (c-2-3), and the monomer (c-2-4-1) is a polycarbonate-modified phosphate group-containing monomer (c-2-4). ).
Styrene and lauryl methacrylate are hydrophobic polymerizable unsaturated monomers, and styrene is an aromatic ring-containing polymerizable unsaturated monomer.
Production Example of Phosphate Group-Containing Resin Production Example 23
120 parts of propylene glycol monomethyl ether was put in a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, nitrogen inlet tube and dropping device, heated to 110 ° C., and kept at the same temperature, “light ester P -1M "(trade name, manufactured by Kyoeisha Chemical Co., Ltd., acid phosphooxyethyl methacrylate, compound in the case where R ¹ is a methyl group and R ³ is an ethylene group in the general formula (2)), 30 parts, styrene 25 Part of a mixture (I) consisting of 3 parts of lauryl methacrylate, 15 parts of lauryl methacrylate, 30 parts of n-butyl acrylate and 3 parts of t-butylperoxy-2-ethylhexanoate was added dropwise over 4 hours, and stirred for 1 hour after completion of the addition. Aged. Thereafter, a polymerization initiator solution consisting of 1 part of t-butylperoxy-2-ethylhexanoate and 30 parts of propylene glycol monomethyl ether was added dropwise over 1 hour, and after completion of the addition, the mixture was stirred and aged for 1 hour to obtain a solid content. A 40% phosphoric acid group-containing resin solution (P-1) was obtained. The obtained phosphate group-containing resin (P-1) had a hydroxyl value of 0 mgKOH / g, an acid value of 140 mgKOH / g, and a number average molecular weight of 8,000.
Production of basecoat paint composition Example 1
In the stirring and mixing vessel, 48 parts of the talc dispersion (B-1) obtained in Production Example 4 and 10 parts of the resin solution (C-1) containing the hydroxyl group and phosphate group obtained in Production Example 18 were mixed. A talc mixture was obtained.
13 parts of the talc mixed solution, the hydroxyl group-containing acrylic resin solution (A1-1-1) obtained in Production Example 1, 83 parts of the hydroxyl group-containing acrylic resin emulsion (A1-1-2) obtained in Production Example 2, and Production Example 3 36 parts of the hydroxyl group-containing polyester resin solution (A1-2-1) obtained in the above, 38 parts of melamine resin (A2-1) (methyl-butyl mixed etherified melamine resin, solid content 80%, weight average molecular weight 1,400) and 44 parts of the color pigment dispersion obtained in Production Example 15 were uniformly mixed, and further, “Primal ASE-60” (trade name, manufactured by Rohm and Haas, thickener), 2- (dimethylamino) ethanol and dehydrated Add ionic water, pH 8.0, paint solids 25%, Ford Cup No. 20 at 20 ° C. An aqueous base coat coating composition (X-1) having a viscosity according to 4 of 40 seconds was obtained.
Examples 2-16, Comparative Examples 1-4
In Example 1, the Ford Cup No. at pH 8.0, solid content of 25%, 20 ° C. was prepared in the same manner as in Example 1 except that the composition was as shown in Table 3 below. Aqueous base coat coating compositions (X-2) to (X-20) having a viscosity according to 4 of 40 seconds were obtained.

(Note 3) Melamine resin (A2-2): methyl etherified melamine resin, solid content 80%, weight average molecular weight 800.
(Note 4) “Carbodilite SV-02” (trade name, manufactured by Nisshinbo Co., Ltd., polycarbodiimide compound, solid content 40%).

(Note 5) “Yukot UX-5000” (trade name, manufactured by Sanyo Chemical Industries, Ltd., urethane emulsion, solid content 40%).
Preparation of test article: Thermosetting epoxy resin cationic electrodeposition coating composition (trade name “Electron GT-10”, manufactured by Kansai Paint Co., Ltd.) with a thickness of 20 μm is applied to a zinc phosphate-treated cold rolled steel sheet. Electrodeposition coating was performed, and the mixture was cured by heating at 170 ° C. for 30 minutes. Next, an intermediate coating composition (trade name “TP-65-2”, manufactured by Kansai Paint Co., Ltd., polyester resin / amino resin organic solvent type coating composition) is formed on the electrodeposition coating film to a film thickness of 35 μm. And cured by heating at 140 ° C. for 30 minutes. Thus, an object to be tested was prepared by forming an electrodeposition coating film and an intermediate coating film on the steel plate.
Coating film forming method Example 17
The base coat coating composition (X-1) obtained in Example 1 was electrostatically applied to the above test object using a rotary atomization type electrostatic coating machine so as to have a cured film thickness of 16 μm. A base coat film was formed. After standing for 3 minutes and preheating at 80 ° C. for 3 minutes, “Magiclon KINO-1210” (trade name, manufactured by Kansai Paint Co., Ltd., carboxyl group-containing acrylic resin and epoxy group-containing acrylic was applied on the uncured base coat film. An organic solvent-type clear coat coating composition containing a resin was electrostatically applied to a cured film thickness of 35 μm using a rotary atomizing type electrostatic coating machine to form a clear coat film. After leaving for 7 minutes, the base coat film and the clear coat film were simultaneously cured by heating at 140 ° C. for 30 minutes to prepare a test coated plate.
Examples 18-32, Comparative Examples 5-8
In Example 17, except that the base coat paint composition (X-1) obtained in Example 1 is changed to any of the base coat paint compositions (X-2) to (X-20) shown in Table 4 below. A test coated plate was produced in the same manner as in Example 17.
Evaluation Test Each test coated plate obtained in Examples 17 to 32 and Comparative Examples 5 to 8 was evaluated by the following test method. The evaluation results are shown in Table 4 below.
(Test method)
Smoothness: The smoothness was evaluated using the Wd value measured by “Wave Scan DOI” (trade name, manufactured by BYK Gardner). It shows that the smoothness of a coating surface is so high that Wd value is small.
Vividness: Evaluated using Wb value measured by “Wave Scan DOI”. The smaller the Wb value, the higher the clearness of the coating surface.
Water-resistant adhesion: After immersing the test plate in warm water at 40 ° C. for 240 hours, pulling it up and drying at 20 ° C. for 12 hours, cut the multi-layer coating film of the test plate into a grid shape with a cutter so as to reach the substrate, Make 100 2mm x 2mm gobangs. Then, the adhesive cellophane tape was stuck on the surface, and the remaining state of the goby eye coating after the tape was rapidly peeled off at 20 ° C. was examined.
(Double-circle): 100 galvanic coatings remain | survive and the small edge of a coating film does not arise in the edge of a cutting of a cutter.
◯: 100 gobanged paint films remain, but small edges of the paint film are formed at the edge of the cutter.
(Triangle | delta): 90-99 pieces of gobang eyes coating films remain | survive.
X: The remaining number of gobang eye coats is 89 or less.
Chipping resistance: A test plate was placed on a specimen holder of a stepping stone testing machine JA-400 (chipping test device) manufactured by Suga Test Instruments Co., Ltd., and at −20 ° C., a distance of 30 cm from a distance of 0.392 MPa (4 kgf / cm ² ) 50 g of granite crushed stone with a particle size of 7 was collided with the test plate at an angle of 45 degrees by compressed air of ² ). Thereafter, the obtained test plate is washed with water, dried, and a cloth adhesive tape (manufactured by Nichiban Co., Ltd.) is applied to the coated surface. After peeling it off, the degree of occurrence of scratches on the coating film is visually observed. And evaluated according to the following criteria.
(Scratch size)
A: Scratches are extremely small.
○: Scratches are small.
Δ: Scratches are large.
X: Scratches are extremely large.
(Scratch depth)
A: The electrodeposition surface and the base steel plate surface are not exposed.
○: The electrodeposited surface is exposed, but the base steel plate surface is not exposed.
(Triangle | delta): The steel plate surface of a base is exposed.
X: The electrodeposition surface and the base steel plate surface are exposed.

Claims (14)

A base coat coating composition for applying immediately before applying a clear coat coating composition when forming a multilayer coating film including at least three coating films on a coating object,
(A) a film-forming resin component,
(B) In the volume-based particle size distribution, the particle size (D ₅₀ ) at which the integrated particle size distribution from the small particle size side is 50% is in the range of 3 to 8 μm, and the particle size is 0.1 μm or more and 3 μm. Talc in which the ratio P _r = P ₂ / P ₁ of the content ratio P ₁ (%) of particles less than 3% and the content ratio P ₂ (%) of particles having a particle size of 3 μm or more and 10 μm or less is in the range of 2 to 5 And (C) a base coat coating composition comprising a resin containing a hydroxyl group and a phosphate group.   The base coat coating composition according to claim 1, wherein the film-forming resin component (A) comprises a hydroxyl group-containing resin (A1) and a curing agent (A2).   The base coat coating composition according to claim 2, wherein the hydroxyl group-containing resin (A1) has a hydroxyl value within a range of 1 to 300 mgKOH / g.   The base coat coating composition according to claim 2, wherein the hydroxyl group-containing resin (A1) is selected from the group consisting of a hydroxyl group-containing acrylic resin (A1-1) and a hydroxyl group-containing polyester resin (A1-2).   The base coat coating composition according to claim 2, wherein the curing agent (A2) is selected from the group consisting of an amino resin, a polyisocyanate compound and a blocked polyisocyanate compound.   Resin (C) containing a hydroxyl group and a phosphate group has a hydroxyl value in the range of 15 to 200 mgKOH / g and / or an acid value in the range of 10 to 200 mgKOH / g and / or a range of 2,000 to 100,000. The base coat coating composition of claim 1 having a number average molecular weight of   Resin (C) containing hydroxyl group and phosphate group is 1-50 parts by mass of hydroxyl group-containing polymerizable unsaturated monomer (c-1), 1-70 parts by mass of phosphate group-containing polymerizable unsaturated monomer (c-2) And a base coat coating composition according to claim 1, which is a copolymer (C ′) obtained by copolymerizing 0 to 98 parts by mass of other polymerizable unsaturated monomer (c-3).   The hydroxyl group-containing polymerizable unsaturated monomer (c-1) is a monoesterified product of (meth) acrylic acid and a dihydric alcohol having 2 to 8 carbon atoms, an ε-caprolactone modified product of the monoesterified product, N-hydroxymethyl ( The base coat coating composition according to claim 7, which is selected from the group consisting of (meth) acrylamide, allyl alcohol and (meth) acrylate having a polyoxyethylene chain whose molecular end is a hydroxyl group. Phosphoric acid group-containing polymerizable unsaturated monomer (c-2) is represented by the general formula (1)

[Wherein R ¹ represents a hydrogen atom or a methyl group, X represents —O— or —NH—, and R ² represents a divalent organic group having 1 to 30 carbon atoms]
The base coat coating composition according to claim 7, which is a polymerizable unsaturated monomer containing a phosphoric acid group represented by the formula:   The phosphate group-containing polymerizable unsaturated monomer (c-2) is an alkylene-modified phosphate group-containing polymerizable unsaturated monomer (c-2-1), an oxyalkylene-modified phosphate group-containing polymerizable unsaturated monomer (c-2). -2), a polyester-modified phosphate group-containing polymerizable unsaturated monomer (c-2-3) and a polycarbonate-modified phosphate group-containing polymerizable unsaturated monomer (c-2-4). The base coat paint composition as described in 1.   Other polymerizable unsaturated monomers (c-3) are a hydroxyl group-containing polymerizable unsaturated monomer (c-1), a phosphoric acid group-containing polymerizable unsaturated monomer (c-2), and other polymerizable unsaturated monomers ( The base coat coating composition of Claim 7 which contains 2-80 mass parts of aromatic ring containing polymerizable unsaturated monomers on the basis of the total amount of c-3). The copolymer (C ′) has a hydroxyl value in the range of 15 to 200 mg KOH / g and / or 10 to 10 mg
The base coat coating composition according to claim 7, having an acid value in the range of 200 mg KOH / g and / or a number average molecular weight in the range of 2,000 to 100,000.   50 to 99.5 parts by mass of the film-forming resin component (A) and 50 to 99.5 parts by mass of talc (100 parts by mass of the total resin solid content of the resin (C) containing a hydroxyl group and a phosphate group. The base coat coating composition according to claim 1, comprising 2 to 50 parts by mass of B) and 0.5 to 50 parts by mass of a resin (C) containing a hydroxyl group and a phosphate group.   An article coated with the base coat paint composition according to any one of claims 1 to 13.