JP3897850B2

JP3897850B2 - VACUUM INSULATION PANEL, CORE MANUFACTURING METHOD, AND REFRIGERATOR USING VACUUM INSULATION PANEL

Info

Publication number: JP3897850B2
Application number: JP04336397A
Authority: JP
Inventors: 芳夫西本
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 1997-02-27
Filing date: 1997-02-27
Publication date: 2007-03-28
Anticipated expiration: 2017-02-27
Also published as: JPH10238938A

Description

【０００１】
【発明の属する技術分野】
本発明は、例えば冷蔵庫や保冷車などの断熱を要する壁面の金属製薄板および樹脂成形品で構成された間隙に断熱材として用いる真空断熱パネルに関するものであり、さらに詳しくは真空断熱パネルの外殻を形成して外気の侵入を遮断して内部の真空を維持する機能を保有する包装材の内部にあって、主に大気圧による加圧から形状を維持する機能を付与された芯材に関するものであり、その材料構成とそれを得るための製造方法に関するものである。
【０００２】
【従来の技術】
近年、地球環境を保護するため、オゾン層破壊速度を抑制するためのクロロフルオロカーボン類、さらにはそれの１／１０以下にまで抑制できるハイドロクロロフルオロカーボン類まで対象となった使用規制が実施され、将来技術として発泡剤を用いずにより一層の断熱性能向上と用いた材料が容易に回収と再利用が可能な断熱システムが社会的に要求されている。
【０００３】
従来、冷蔵庫や保冷車などの断熱体の壁面は、その外郭を鉄板などの金属製薄板、内面部分を樹脂成形品で形成され、その間隙を断熱性に優れた硬質ポリウレタンフォームを注入発泡して充填させたものが用いられてきた。
【０００４】
断熱材である硬質ウレタンフォーム（ＰＵＦ）の発泡剤には優れた断熱性が得られるハイドロクロロフルオロカーボン類である１，１−ジクロロ−１−フルオロエタンが用いられてきたが、近年、オゾン層破壊の原因となる塩素を分子中に含まないハイドロフルオロカーボン類やハイドロカーボン類を用いることが提案されている。
例えば、特開平２−２３５９８２号公報では、1,1,2,2,3-ペンタフルオロプロパン（以後、HFC-245fa という。）や、1,1,1,4,4,4-ヘキサフルオロブタン（以後、HFC-356mffm という。）などのハイドロフルオロカーボン類を、特開平３−１５２１６０号公報ではシクロペンタンなどの可燃性物質を、各々、発泡剤に適用した硬質ポリウレタンフォームの製造方法について述べられている。しかし、これら硬質ウレタンフォームの冷蔵庫などへの適用品で最も優れた断熱性は１７〜２０mw/mK である。
【０００５】
オゾン層破壊の原因物質を用いないこと、リサイクルなどの資源の有効活用、これにに併せて消費電力の低減が求められている冷蔵庫などでは、断熱材である硬質ウレタンフォームに対する断熱性能向上が限界にあることから、図１の各断熱材の性能比較図に示す如く、硬質ウレタンフォームの２倍以上の断熱性能が得られる真空断熱パネルを応用する技術が新たに提案されている。
例えば、特開昭６０−２４３４７１号公報ではＰＵＦ粉砕品を合成樹脂袋に投入してボード状に真空パックしたものを壁内に配設した断熱箱体があり、特開昭６０−６０４８３号公報では側板のフランジ側にＰＵＦが流動する隙間を設けた真空断熱パネルの設置方法を提案している。
【０００６】
以上の提案をはじめとする多くの真空断熱パネルの形状は、厚さが１０〜２０mmの板状であり、図２に示す工程を経て図３の断面図の如く状態で冷蔵庫の壁に組み込んだ状態で作られる。このため、真空断熱パネルの芯材には、真空状態のパネル形状を保持する機能を満足するために所定の強度を有することが必要となる。
【０００７】
一方、真空断熱パネルの断熱性能向上には、構成する材料に熱が伝達し難い物質を用いること、材料間の接触面積を少なくすること、熱伝達を断熱方向と直角の面方向に制御することが重要になる。これによって断熱（厚さ）方向に物質を伝達する熱量を抑制、更に輻射伝熱を抑制する物質を介在させたり、空隙の大きさを小さくすることが輻射伝熱を抑制するうえで有効となる。
【０００８】
上記条件を満たすものとして多くの提案があり、例えば特開昭６０−２０５１６４号公報では連通気泡の硬質ウレタンフォームを、特開昭６０−７１８８１号公報ではパーライト粉末を、特開平４−２１８５４０号公報では熱可塑性のウレタン樹脂粉体を型内で焼結させた板状成形品、特開平７−９６５８０号公報ではグラスの長繊維と無機微粉末をフィビリル化した樹脂繊維により固化保持したボードを各々、真空断熱パネルのコア材として応用している。
【０００９】
これら物質の適用に関し、断熱性能の向上を達成するために断熱方向と直角に繊維を配設して熱伝達量を抑制した特開昭６０−２０８６９６号公報や特開昭５８−１０６２９２号公報、輻射熱の遮蔽効果に優れる金属箔または金属蒸着フィルムを埋設するした特開昭６２−１３９７９号公報やケイ酸カルシウム等の微粉末を混合したＰＵＦを用いる特開昭６３−１３５６９４号公がある。
【００１０】
【発明が解決しようとする課題】
断熱性能の向上には、構成する材料に熱伝導の低い物質を用いること、材料間の接触面積を少なくすること、熱伝達を断熱方向と直角の面方向に制御することにより断熱（厚さ）方向に物質を伝達する熱量を抑制、さらに熱の反射能力の高い物質を混入させて輻射伝熱の減少を両立させて伝熱と輻射熱を抑制する断熱機構が必要となる。
しかし、従来の方法ではこれら真空断熱パネルの芯材として必要な断熱機構を一部しか応用していない芯材構造であるため、真空断熱パネルとしての断熱性能が不十分であった。
【００１１】
つまり、ケイ酸カルシウムやパーライト等の粒状物質やグラス繊維で代表される繊維状物質をそのまま板状に成形するなどして真空断熱パネルの芯材に用いると、物質間の接触を減らすことによって熱伝達の抑制が達成できるものの、物質が無配向であることによって断熱方向にも物質を伝わる伝熱が抑制できなかったり、繊維を配向させたとしても輻射断熱の抑制がその物質の熱反射にのみ依存するなど、必ずしも上述した断熱機構を十分に応用した芯材構造を得ていない。
【００１２】
一方、輻射伝熱の抑制を目的に金属箔を配設した芯材であっても、伝熱が面方向に展開するのみで減衰することがないから、物質間の伝熱に対する抑制を得た構造ではない。
【００１３】
しかも、粒子（粉末）状や繊維状の物質をそのままで用いようとするならば、芯材の変形を無くすために圧縮強度を向上させる工夫や嵩密度を上げる為の処理を十分に行う必要がある。つまり、これら処理を行わずにそのままの状態であれば、真空断熱パネルへの挿入および所望する形状が容易に得られないうえ、包装用の袋内を真空状態にした後の体積減少が大きいために、取り扱いが固化された材料のように簡易に行うことが困難となる。しかも、この体積減少に伴う変形によって包装材が折れ曲がり、亀裂発生などの欠陥の発生によって真空が維持できなくなる可能性もある。
【００１４】
この発明は、構成する物質の熱伝導が低くく、物質間の接触面積が少なく、断熱（厚さ）方向に物質を伝達する熱量を抑制し、さらに伝熱と輻射熱を抑制する断熱機構を具備した真空断熱パネルを提供することを目的とする。
また、上記のような真空断熱パネルに用いる芯材の製造方法を提供することを目的とする。
さらに、上記のような真空断熱パネルを断熱材として用いる冷蔵庫を提供することを目的とする。
【００１５】
【課題を解決するための手段】
この発明は上記問題点を解決するために、真空断熱パネルの芯材を、包装材の形状を保持し、グラスウールマットの面上に輻射熱の遮蔽効果に優れた輻射熱遮蔽部材を積層した複素体で構成した。
また、グラスウールマットを、断熱方向に直角な面方向にグラスウールを堆積させて構成した。
また、輻射熱遮蔽部材を板状片で構成した。
また、板状片をはマイカフレークで構成した。
また、板状片を金属箔で構成した。
また、板状片をプラスチックフィルムに金属の薄膜を被覆したもので構成した。
また、板状片の密着を抑制する密着抑制剤を用いた。
【００１６】
また、真空断熱パネルの芯材を、グラスウールマット上に板状片を配設して複素体を作製する複素体作製工程と、複素体作製工程で得られた複素体の水分の除去を行う乾燥工程と、乾燥工程で乾燥した複素体を樹脂の溶液中に浸漬する含浸工程と、含浸工程で樹脂を含浸させた複素体を一定の加圧力を付与しながら硬化させて成形する圧縮硬化成形工程とにより製造するものである。
また、複素体作製工程で、板状片を均一分散させたスラリー液をグラスウールマットで抄きあげるようにした。
また、複素体作製工程で、板状片を均一分散させたスラリー液をグラスウールマット上に散布するようにした。
【００１７】
また、スラリー液に、板状片の他に板状片同士を固定化し、板状片同士の密着を抑制する結合材と、グラスウールマットの表面に結合材の一部を結合させ易くする凝集剤とを含有させた。
また、凝集剤にアクリルアミドを用いた。。
また、結合材にミクロフィブリル化したセルロース繊維を用いた。
また、含浸工程における樹脂に、半硬化状態の熱硬化性樹脂または熱可塑性樹脂を用いた。
また、圧縮硬化成形工程で、含浸工程で樹脂を含浸させた複素体を４〜１２層重ねて成形した。
また、圧縮硬化成形工程における加圧力を０．７〜１．５kg/cm2とした。
【００１８】
また、冷蔵庫の外箱と内箱とを嵌合して形成される間隙部に、この発明の真空断熱パネルを配設して断熱材として用いた。
さらに、間隙部において真空断熱パネルが配設されていない他の空隙部に硬質ポリウレタンフォ−ムを充填した。
【００１９】
【発明の実施の形態】
実施の形態１．
以下、この発明の実施の形態１を図及び表を用いて説明する。
１．芯材の作成方法
以下に、グラスマット上に輻射熱遮蔽部材である板状片としてマイカを配設させた芯材を例として、その作成方法を述べる。
図４は真空断熱パネルの製造工程図であり、この製造工程図に芯材の作成方法の概念を示し、方法の詳細を以下に述べる。
（１）板状片（板状充填材）の調整
この発明における輻射熱遮蔽部材である板状片（板状充填材）に必要な機能は熱反射性に優れていることが重要であり、従って、金属または無機物などの高密度な物質が好ましい。板状片（フレーク）形成の容易性から反映される価格から鑑みても、アルミ箔又はマイカを用いることが最も好ましい。
また、低密度物質であるプラスチックのフィルムであっても、表面にアルミなどの金属薄膜を被覆して用いれば、同様の効果を得ることができる。
ここではマイカをフレーク状にして用いた例を用いて説明する。マイカは粉砕器を用いて直径が０.１mm以上、好ましくは５〜０.５mm、更に好ましくは２mm程度の大きさに粉砕する。このときの粉砕にはウオータージェットによる高速水流を応用すれば、層間の引き剥がしも同時に行われて、より薄いフレーク状のマイカが得られるので好ましい。
【００２０】
（２）スラリー液の作製
マイカは１０wt％以下、好ましくは０.１〜５wt％、更に好ましくは０.５〜３wt％の濃度で水中で撹拌しながら分散させる。このときの撹拌の強さは、マイカが沈降して濃度に不均一が生じさせないことは当然であるが、他にもマイカの粉砕が進行しないように調整することが好ましい。
次に、結合材であるミクロフィビリル化したセルロース繊維（略称；ＭＦＣ）をマイカの投入量に対して０．５〜５wt％、好ましくは１〜３wt％を投入、均一分散させる。この場合の投入量は、一般にミクロフィビリル化したセルロース繊維が５〜１０wt％の濃度で水に分散させた高粘度スラリー状のものが販売されており、これを乾燥させた固体量にて換算することが必要である。ここで、ミクロフィビリル化したセルロース繊維を用いたのは、極めて少量の添加によってマイカ同士を固定化させると共に、直径が１ミクロン以下の繊維がマイカの層間に介在することになるので、マイカ同志の密着が抑制できる。しかも、そこで形成される多くの微小空間が固体伝熱を遮断し、より輻射熱の断熱効果が得られるためである。
マイカ同志の密着を抑制する効果は、密着抑制剤である微粒子をマイカ表面に付着させることによって、マイカ同志の密着防止と空間形成を行うことでより有効な効果が得られる。このときに用いる微粒子の大きさは１００ミクロン以下が好ましく、更に好ましくは１０ミクロン以下である。
最後に、凝集剤をマイカの投入量に対して０.０１〜１wt％、好ましくは０.０５〜０．２wt％を投入する。この凝集剤の投入によって、マイカの表面にミクロフィビリル化したセルロース繊維の端部が十分に結合する結果となり、マイカ同志またはグラス繊維との固定をより強固なものとすることができる。凝集剤としては、アクリルアミドが一般的で最も好ましいが、このほかにもポリエチレンイミンやキト酸、デンプンなどが利用できる。
もし、ミクロフィビリル化したセルロース繊維を使用しなければグラスマットとマイカおよびマイカ同志などの充填材の固定が不十分となり、すぐにグラスマットとマイカとの複素体が分解するなど、取り扱い性に極めて劣るものしか得られない。
また、ここで凝集剤を使用しなければ、スラリー液内でミクロフィビリル化したセルロース繊維と、グラスマットとマイカおよびシリカなどの粒子との結合が不十分になるので、充填材の固定が不十分で不均一なものしか得られなくなるという問題が発生する。
【００２１】
（３）スラリー液の抄きあげ
グラスマットは１kg/cm2の圧縮荷重を付加させたときの厚さが２０mm以下、好ましくは１０mm以下、更に好ましくは２〜５mmの厚さのものを用い、しかも、みかけの厚さに対する寸法変化率が１／２０以上、好ましくは１／５程度の密度のもの選択する。スラリー液の抄きあげは図５に示す如く、筒状容器９の底部に配置したグラスマット上に、マイカなどを分散させたスラリー液６を投入、マイカが沈降して液上部が透明になるまで１〜３分間の静置の後、容器下部のドレン抜き８から排水することによって、グラスマット５上にマイカと並行して配設させた複素体が得られる。このとき、排水を真空ポンプなどを用いて強制的に行えば、短時間に残存水分の少ない効率的な排水となるうえ、直径の小さなマイカのみが上部に堆積することによって剥がれやすくなるという不具合も防止できる。
図４の製造工程では、図５に示すスラリー液の抄きあげにより複素体を得たが、板状片を均一分散させたスラリー液をグラスウールマット上に散布することでも同様の効果が得られる。
【００２２】
（４）乾燥
得られた複素体は、以降の工程における品質を安定化させる為、高温雰囲気下に放置して水分の除去を十分に行う。このときの乾燥温度は、ミクロフィビリル化したセルロース繊維のマイカおよびグラス繊維との結合力に劣化が生じ得ない１５０℃以下、好ましくは１００〜１２０℃の雰囲気下で乾燥させ、しかも圧縮によって複素体の嵩密度が小さくすることができる回転ドラムの表面に張り付けた後、乾燥初期の重さによって試料が落下するのを防止するために固定用ベルトやロールの間を通過させるようなヤンキードライヤー式が有効である。これ以外にも、乾燥炉を用いたり、併用することも有効である。
【００２３】
（５）樹脂の含浸
乾燥した複素体は、熱硬化性樹脂の溶液中に浸漬後、引き上げて十分に過剰な樹脂を滴下、除去させ、更に乾燥を行うことによって樹脂の溶剤を除去させる。このとき、用いる熱硬化性樹脂は成型時に溶融する半硬化状態が制御可能な、エポキシ樹脂が最も好ましく、これ以外にもポリエステルやポリイミドを用いることも可能である。
又、熱硬化性樹脂に変えて、熱可塑性樹脂を用いることも有効である。
一方、含浸させる樹脂の量は、圧縮硬化成形後にグラス繊維やマイカ堆積層表面に樹脂が完全に覆うことによって真空脱気に支障が来さないようにすることが重要である反面、圧縮による変形を維持できる量を確保することも必要であるから、その範囲を限定することとなる。含浸させる樹脂の量は、複素体の重量に対し、１〜２０wt％が好ましく、５〜１０wt％が更に好ましい。この、含浸させる樹脂の量は樹脂液中の樹脂濃度と樹脂液の粘度によって経験的に調整する。
【００２４】
（６）圧縮硬化成形
半硬化状態の樹脂を含浸させた複素体は、樹脂の反応に適した硬化条件、つまり温度と時間、さらに一定の圧力を保持した熱板の間に挟んで、ボード状に成形される。このときの硬化条件は樹脂の種類によって異なるが、エポキシ樹脂の場合は１２０〜１８０℃で１時間以内の硬化、つまり成形が完了するように調整する。この工程で最も重要なのは圧縮力であり、圧縮によって繊維同志の点接触機会を増して固化を充実させる必要がある反面、グラスやマイカそれに樹脂などの固体成分量が増えると断熱性の低下が大きくなる。そのために、圧縮荷重には範囲が限定され、０.５〜３kg/cm2が好ましく、０.８〜１.５kg/cm2 が更に好ましい。
試料となる芯材は、所定厚さを得るために、樹脂を含浸させた複素体の複数枚を重ねて合わせて調整した圧縮成形品を用いた。
【００２５】
２．真空断熱パネルの作成方法
図４の製造工程図を用いて、真空断熱パネルの形成方法を述べる。
予め３方向を熱シールした包装材内に芯材を挿入した後、図６に示す装置を用いて所定の真空度の雰囲気中で残った１方向を熱シールすることによって図７に示す内部構造を有する真空断熱パネルが得られる。
このとき、包装材のシール面には熱溶着が可能な熱可塑性樹脂が用いられ、中間層には外気の侵入を完全に遮断するためのアルミ箔などの金属箔などが用いられ、更に最外層には傷つきなどに耐性のある樹脂が用いられている。このように、単一のフィルムではなく、３層以上で構成された多層シートを用いることが好ましい。試料には、所定の大きさを得るために芯材を裁断して調整した。
【００２６】
２．評価の方法
芯材の評価は上述したようにして得られた真空断熱パネルを用いて、断熱性能と形状の経時変化を含む特性について行った。
試料である真空断熱パネルは芯材として厚さが２０mm、面の大きさが１８０＊１８０mmに調整したものを用い、包装材としてナイロン、アルミ箔、ポリエステル、さらにアルミ箔の上下面がポリエステル系の接着剤の介在で構成された５層シートを用いた。真空断熱パネル内の真空度は１０１〜１０−３Torrの間の任意の値とし、断熱性能の評価は栄光精機（株）社製の「オートラムダ」を用いて熱伝導率で行った。
【００２７】
【実施例】
実施例１．
以下に本発明の実施の形態の具体的な実施例の断熱性能の向上効果を確認した結果について述べる。
まず、グラスマットと板状充填材の複素体に接着剤を塗布したプリプレグの主たる成分の組成を表１に示す。
【００２８】
【表１】

【００２９】
図５の装置を用いてグラスマット上に板状充填材であるマイカ又はアルミ箔に、ＭＦＣと少量のアクリルアミドを分散させたスラリー液投入、５分間の静置後に強制吸引して水を除去して抄きあげたグラスマットと板状充填材の複素体をオーブン中の１００℃×２０分間の条件で乾燥させた。ここで用いたグラスマットの厚さは、１kg/cm2の荷重下で５mmの厚さになるものを選択した。また、フレーク状マイカは平均直径が３mmのもの、アルミ箔は２０μｍ厚さで平均直径が５mmに裁断したもの、密着防止の為に用いるシリカ粒子は平均粒径が５μｍのものである。
【００３０】
以上の方法で得たグラスマットと板状充填材の複素体は、樹脂原料のビスフェノールＡとエピクロルヒドリンに、溶剤としてメチルセルソルブを用いて成るエポキシ樹脂液に含浸した後、網上に約３０分間の放置によって過剰のエポキシ樹脂液を滴下させた。その後、１２５℃のオーブン中で１時間の加熱・乾燥を行うことによって溶剤の除去と反応の進行による半硬化状態のエポキシ樹脂重合体をグラスマットの繊維および板状充填物の表面に被覆させたプリプレグを得た。
【００３１】
以上のプリプレグを１８０×１８０mmの大きさに裁断した後、同一の大きさを有する平板金型内に４枚を金型内にて重ねて配設し、１２０℃で１０−１Torrの真空雰囲気下で１０分の放置をした後、加圧下にて１８０℃まで１０分で昇温、さらに４０分の放置によって完全硬化、室温付近まで降温後、成型品である芯材を取り出した。このとき、プリプレグにかかる荷重は、金型の重量の含めて１．２kg/cm2とした。
【００３２】
上記方法によって得られた芯材を用いて、包装材の内部が１０１〜１０−３Torrの間の任意の真空度である真空断熱パネルを作製し、これの熱伝導率を測定した。得られた図８に示すような真空度と熱伝導率の関係曲線から、０.１Torr に相当する真空度の熱伝導率と、急激に熱伝導率が上昇する臨界真空度を求め、その結果を表２に示す。一方、真空断熱パネルの大気圧による変形は、目視によって確認した。
【００３３】
また、従来品に相当するグラスマット単体および連通硬質ポリウレタンフォ−ムを芯材に用いた真空断熱パネルを従来品として比較試料１および比較試料２として示した。比較試料２として示した連通硬質ポリウレタンフォ−ムは気泡を形成するセル膜に穴があいており、これによって内部に残存する空気を容易に排出できる構造になっており、これの同等品を芯材に用いた真空断熱パネルは現在、冷蔵庫などに用いられている。
【００３４】
【表２】

【００３５】
以上の結果から、本実施例による試料１〜４の真空断熱パネルは従来品に相当する比較試料として示したグラスマット単体および連通硬質ポリウレタンフォ−ムと比較して、熱伝導率で示される断熱性能が格段に向上していることが明白である。
【００３６】
また、臨界真空度が従来品と比較して高いことから、包装材などを通して真空断熱パネル系内に侵入してくるガスなどによる真空度低下がもたらす断熱性能劣化の耐力にも優れていると言える。さらに、変形に対しても実用上、十分な抑制力を有している。
【００３７】
上記方法によって芯材の低熱伝導率化の機構は定かではないが、恐らく以下のごとき要因を有しているものと推測する。グラスマットは、ほぼ面方向に堆積させた数ミリから数十ミリの長さのグラス繊維で構成されており、不規則に絡んだ構造を有しているから、繊維同志の接触間には多くの空隙が確保できるという特徴を有している。これによって、軽量化を確保できるとともに、繊維同志の接触部分が微小な面積に抑制できることから、面方向と直角にある伝熱を抑制でき、断熱効果を得ることができる。
【００３８】
一方、輻射熱の遮蔽効果に優れた板状物質を、それ同志が微粒子等により直接接触しないように積層してグラスマットの上に重ねた様な構造である複素構造を成すことにより、輻射熱の断熱を有効に確保できる。しかも、板状物質がグラスマットの伝熱係数より大きくとも、極めて薄い層であるから、厚さ方向への板状物質を伝わる熱がもたらす断熱効果悪化への影響もほとんどない。この結果、従来のグラスマットのみを芯材に用いた場合と比較して、板状物質の配設による伝熱の増加よりも輻射伝熱量の低下が有意に上回るので、真空断熱パネルに用いたときの断熱性能向上が達成できるものと推測する。
【００３９】
実施例２．
次に、板状充填材と微粒子を併用する効果を確認した。主たる成分の組成を表３に示す。
【００４０】
【表３】

【００４１】
板状充填材であるマイカとマイカ同士の密着防止の為に用いるシリカ微粒子とミクロフィブリル化したセルロース繊維の混合・分散させたスラリー液を、１kg/cm2の荷重下で５mmの厚さになるグラスマット上に、図５に示す装置を用いて散布、下部より過剰の水分を強制吸引して除去して抄きあげた。なお、ここで用いたフレーク状マイカは平均直径が３mm、シリカ粒子は平均粒径が１０μｍのものである。このようして得たグラスマットを１００℃×２０分間の乾燥条件にてオーブン中に放置、水分を完全に除去し、これと板状充填材の複素体は、樹脂原料のビスフェノールＡとエピクロルヒドリンに溶剤としてメチルセルソルブを用いて成るエポキシ樹脂液に含浸後、網上に約３０分間の放置によって過剰のエポキシ樹脂液を滴下させた。その後、１２５℃のオーブン中で１時間の加熱・乾燥によって溶剤の除去と反応の進行による半硬化状態の重合物をグラスマットの繊維および板状充填物の表面に被覆させたプリプレグを得た。
【００４２】
以上のプリプレグを１８０×１８０mmの大きさに裁断した後、同一の大きさを有する平板金型内に４枚を重ねて配設し、１２０℃で１０−１Torrの真空雰囲気下で１０分の放置後、１８０℃まで１０分で昇温、さらに４０分の放置によって完全硬化後、室温付近まで降温後、取り出した。このとき、プリプレグにかかる荷重は、金型の重量の含めて１.２kg/cm2とした。
【００４３】
上記方法によって得た芯材を用い、包装材の内部が１０１〜１０−３Torrの任意の真空度で真空断熱パネルを作製、これを室温で５日間放置した後に熱伝導率を測定し、得られた真空度と熱伝導率の関係曲線から０.１Torr に相当する真空度の熱伝導率と、急激に熱伝導率が上昇する臨界真空度を求めた。その結果を表４に示す。また、マイカの層間に固定されて板状充填材であるマイカ同士が密着しないようにする役割を担うシリカ粒子を用いないものと、マイカと同重量添加した組成の場合を各々、比較試料３および比較試料４に示した。
【００４４】
【表４】

【００４５】
以上の結果から、本実施例による真空断熱パネルの芯材における板状充填材であるマイカに微粒子であるシリカ粒子を併用する効果を試料４〜７に示した。この添加範囲におけるシリカ微粒子の効果に差異はないが、比較例として示したマイカのみを使用した比較試料３と比較すれば、臨界真空度に差異はないものの、熱伝導率で示される断熱性能が有意に優れている。これは、板状充填材どうしが密着して単一層として作用することによるものと考えられ、微粒子を板状充填材の層間に固定して空隙を設けることの有効性が確認できた。
【００４６】
一方、板状充填材の過剰添加は比較試料４との比較において確認できるものであり、シリカ微粒子の２５部添加による臨界真空度の差異がない反面、熱伝導率で示される断熱性能の低下が認められた。これは、シリカ微粒子の過剰量が凝集し、その凝集で作られた空間をエポキシ樹脂が被うことによって、独立した空間を形成、この空間内に残存した溶剤のメチルセルソルブや空気などが後に、真空断熱パネル内の真空度を低下させる要因を生むことによるものと予測する。
【００４７】
実施例３．
次に、プリプレグの圧縮成型時にかける荷重についてその効果を確認した。主たる成分は表１および表３にて示した試料４を用いた。
プリプレグの作成は、すでに述べた実施例１および実施例２で述べた内容と同様の方法で行った。つまり、表面に付着したフレーク状マイカを１kg/cm2の荷重下で５mmの厚さになるグラスマット上に配設した複素体をエポキシ樹脂液に含浸後、加熱・乾燥による半硬化状態の重合物をグラスマットの繊維および板状充填物であるマイカの表面に被覆させたプリプレグを得る。得られたプリプレグを１８０×１８０mmの大きさに裁断後、平板金型内に４枚を重ねて配設した状態で１２０℃で１０−１Torrの真空雰囲気下で１０分間放置後、任意の荷重をかけて１８０℃まで１０分間で昇温後、さらに４０分間保持して完全硬化後、室温付近まで降温させて取り出すことにより、真空断熱パネルの芯材を作成した。
【００４８】
このとき、プリプレグにかかる荷重は、金型の重量を含めて０.７〜１.５kg/cm2を好ましい範囲として試料に、プリプレグにかかる荷重が好ましい範囲よりも低い０.５kg/cm2のものと逆に高い１.８kg/cm2のものを比較試料とする芯材を用い、包装材の内部が１０１〜１０−３Torrの任意の真空度で真空断熱パネルを作製、これの熱伝導率を測定した。真空度と熱伝導率の関係曲線から、０. １Torr相当の真空度における熱伝導率と、急激に熱伝導率が上昇する臨界真空度を求め、その結果を試料４および試料８〜１０と比較試料５〜６として表５に併記した。一方、大気圧による変形に対しては目視によって確認した。
【００４９】
【表５】

【００５０】
以上の結果から、真空断熱パネルの芯材成形にかかる圧縮成形荷重の違いは、試料８〜１０で示した０.７〜１.５kg/cm2の範囲内における圧縮成形荷重の影響による熱伝導率、臨界真空度に差異を生じない。しかし、比較試料５として示した低圧縮成形荷重では臨界真空度と断熱性能の指標である熱伝導率と同等であるものの、冷蔵庫などに搭載した場合に意匠性を損なうような変形を確認した。
【００５１】
逆に、比較試料６として示した高圧縮荷重では変形がないものの、熱伝導率を有意に大きくして断熱性能が劣ることを確認した。
【００５２】
これは、各充填材の間隔が必要以上に小さくなり、過剰となった樹脂が空隙を部分的にあっても埋めて密閉空間を形成してしまう。その結果として、この中に残存した溶剤のメチルセルソルブや空気などが、後に真空断熱パネル内の真空度を低下させて熱伝導率が悪化する要因として作用するものと推測する。
【００５３】
実施例４．
次に、真空断熱パネルの芯材と成す際の積層に関する効果を確認した。主たる成分は表１および表３にて示した試料４を適用した。
つまり、マイカとシリカ粒子を１kg/cm2の荷重下で１〜５mmの任意の厚さになるグラスマット上に配設した複素体をエポキシ樹脂液に含浸後、加熱・乾燥させることによって半硬化状態の重合物をそれら表面に被覆させたプリプレグを得る。このプリプレグを１８０×１８０mmに裁断後、平板金型内に複数枚を重ねて配設した状態で１２０℃の加温下で１０−１Torrの真空の雰囲気下で１０分間の放置後、金型重量を含めて１．２kg/cm2の荷重をかけて１８０℃まで１０分間で昇温、さらに４０分間の放置によって完全硬化させた後に室温付近まで降温させた状態で取り出すことにより、真空断熱パネルの芯材を作成した。
【００５４】
このとき、グラスマットとマイカなどの充填材を複素化させたプリプレグを金型内で重ねる数、つまりプリプレグ積層枚数が４〜１２枚を好ましい範囲として試料４および試料１１〜１３、更にプリプレグ積層枚数として好ましい積層数より少ない２枚と、逆に過剰に積層した１９枚のものについても試料７と比較試料８として得た芯材を用い、包装材の内部が１０１〜１０−３Torrの任意の真空度で真空断熱パネルを作製、これの熱伝導率を測定した。真空度と熱伝導率の関係曲線から、０.１Torr の真空度における熱伝導率と、急激に熱伝導率が上昇する臨界真空度を求めた。その結果を表６に併記した。
【００５５】
【表６】

【００５６】
以上の結果から、試料４と試料１１〜１３で示した４枚〜１２枚の積層枚数の増加によって臨界真空度がわずかに上昇する傾向を有するのみで、熱伝導率には差異が認められなかった。しかし、積層枚数の少ない比較試料７で熱伝導率にわずかな低下と臨界真空度の明白な低下がみられた。さらに、比較試料８として示した積層枚数が多すぎる場合には臨界真空度がわずかに優れる反面、熱伝導率が有意に高くなり、断熱性能の低下を確認した。
【００５７】
これは、板状充填材であるマイカが真空下での成型時に、芯材内部に残存した溶剤や空気などの排出が容易に行われず、これら残存ガスが真空断熱パネルとなった状態で経時的に系内の真空度を低下させて、熱伝導率の悪化要因になったものと予測する。
【００５８】
実施例５．
次に、本発明における真空断熱材を用いた冷蔵庫の運転性能を測定し、その効果を確認した。
まず、アルミ箔を中間層に有する包装材を用いて実施例１に示す試料４と同じ方法で作製した真空断熱パネルを用い、薄板鋼板の折り曲げ加工によって得られた外箱にＡＢＳ樹脂の真空成型によって得られた内箱を勘合して形成される間隙に、図３に示す如く、天井面、冷凍室および冷蔵室の左右側面、背面の合計６枚を外箱側に貼り付けて配設した後、残りの空隙に硬質ウレタンフォームを注入・発泡して充填させることで完全固定させた。
【００５９】
上記方法で作製した断熱箱体を用いて冷媒回路などを配設し、４００Ｌクラスの冷蔵庫を組み立て、これを試作冷蔵庫とした。一方、実施例１に示した比較試料２と同じ方法で作製した芯材を連通気泡の硬質ウレタンフォームを芯材とした真空断熱パネルを用いて、同様に作製した断熱箱体を用いた冷蔵庫を比較冷蔵庫１、内箱と外箱の間隙のすべてが硬質ウレタンフォームで充填した断熱箱体を比較冷蔵庫２とし、これらすべての冷蔵庫をＪＩＳ−Ｃ９６０７における消費電力Ｂ法測定法に準拠して消費電力を求め、表７に併記した。
【００６０】
【表７】

【００６１】
以上の結果から、本発明によるグラスマット上にフレーク状マイカを積層した構造の芯材を有する真空断熱パネルを配設した冷蔵庫は、硬質ウレタンフォ−ムのみを断熱材とする比較冷蔵庫２に比べてはるかに小さな消費電力量を示すのみならず、一般に用いられている連通気法の硬質ウレタンフォ−ムを芯材とする真空断熱パネルを用いた比較冷蔵庫１と比較しても優位に優れた消費電力量を醸し出すことが解った。
【００６２】
これは、実施例１にて示されたように、この発明の真空断熱パネルの断熱性能が従来の真空断熱パネルと比較しても有意に優れていることに基づくものである。
【００６３】
以上、冷蔵庫への適用を模擬した真空断熱パネルの構造と、それを得るための組成ならびにその製造方法に関する実施例の断熱特性の指標となる熱伝導率と、安定した断熱性能が確保できる臨界真空度と、外観変形の有無について評価した。
その結果、従来のグラスマットや連通気泡硬質ポリウレタンフォームを芯材に用いた真空断熱パネルに対し、本発明によるグラスマットに熱反射特性に優れた板状充填材を積層したうえ含浸させた樹脂によって固化して得られる複素構造体を芯材に適用することによって、冷蔵庫などの断熱材として用いるうえで優れた断熱特性と外装面の変形を抑制するうえで適しているといえる。
【００６４】
実施の形態２．
以上述べた実施の形態１では、実施例として冷蔵庫とその扉などに真空断熱パネルを用いるものを示したが、冷蔵庫に限定されるものではなく、例えば車載用の小型冷蔵庫やプレハブ式簡易冷蔵庫、保冷車やパイプや建築物の保温材など、保温および／または保冷用製品の部品としても応用が可能であり、その要旨を脱し得ない範囲で種々変形して実施することができる。
【００６５】
【発明の効果】
以上のように、この発明の真空断熱パネルによれば、グラスウールマット上に積層した輻射熱遮蔽部材により、輻射伝熱を減少させる効果を奏する。
また、マイカフレークや金属箔は、板状片の形成が容易である。
また、板状片の表面に密着抑制剤を付加させることで、板状片同志の密着を抑制減少して、断熱性能が向上する。
また、この発明の真空断熱パネルの芯材は、樹脂を含浸させた複素体を一定の加圧力を付与しながら硬化させて成形しているので、真空断熱パネル内を真空にしても、包装材内が使用中に変形することもない。
また、板状片を均一分散させたスラリー液をグラスウールマットで抄きあげるのみで、板状片をグラスウールマット上に容易に配設することができる。
また板状片を含むスラリー液をグラスウールでの上に散布するのみで、板状片をグラスウールマット上に容易に配設することができる。
また、凝集剤と結合材により、スラリー液をグラスウール上に捕捉しやすくしているうえに、結合材によって固定化させることができるので、樹脂含浸でも剥がれることもなく、安定して保持できるので、取扱いが容易である。
また、この発明の真空断熱パネルを断熱材として用いた冷蔵庫は、断熱材が従来の硬質ウレタンフォ−ムのみ、さらには連通気泡の発泡ウレタンを芯材に用いた真空断熱パネルを配設した冷蔵庫に比較して有意に消費電力が少なく、断熱性に優れている。
さらに、隙間部の余った空隙が硬質ウレタンフォームで保持されているので強固に固定され、従来の冷蔵庫となんら変わりのない外観が確保できる。
【図面の簡単な説明】
【図１】各断熱材の断熱性能比較図である。
【図２】真空断熱パネルを搭載した冷蔵庫の製造工程図である。
【図３】冷蔵庫断面における真空断熱パネルの配設図である。
【図４】この発明の真空断熱パネルの製造工程図である。
【図５】この発明の板状物質をグラスマット上に配設させるための抄造装置の概念図である。
【図６】真空雰囲気下で端辺を融着させる真空断熱パネル製造装置の概念図である。
【図７】真空断熱パネルの断面図である。
【図８】真空度と熱伝導率の関係の一例を示すグラフ図である。
【符号の説明】
１冷蔵庫の外箱、２冷蔵庫の内箱、３真空断熱パネル、４硬質ポリウレタンフォ−ム、５グラスマット、６スラリー液、７ドレン液、８ドレン抜き（金網）、９筒状容器、１１真空パネル成形機、１４包装材、１５芯材。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vacuum heat insulation panel used as a heat insulation material in a gap constituted by a metal thin plate and a resin molded product of a wall requiring heat insulation such as a refrigerator or a cold car, and more specifically, an outer shell of a vacuum heat insulation panel Concerning a core material that has the function of maintaining the shape from pressurization by atmospheric pressure, which is inside the packaging material that has the function of blocking the intrusion of outside air and maintaining the internal vacuum The present invention relates to the material configuration and a manufacturing method for obtaining the material configuration.
[0002]
[Prior art]
In recent years, in order to protect the global environment, chlorofluorocarbons for suppressing the ozone depletion rate, and hydrochlorofluorocarbons that can be reduced to 1/10 or less, have been implemented. As a technology, there is a social demand for a heat insulation system that can further improve the heat insulation performance and easily recover and reuse the used material without using a foaming agent.
[0003]
Conventionally, the wall surface of a heat insulator such as a refrigerator or a cold car is made of a thin metal plate such as an iron plate and the inner surface part is formed of a resin molded product. Filled ones have been used.
[0004]
1,1-dichloro-1-fluoroethane, a hydrochlorofluorocarbon that provides excellent heat insulation properties, has been used as a foaming agent for rigid urethane foam (PUF), which is a heat insulating material. It has been proposed to use hydrofluorocarbons and hydrocarbons that do not contain chlorine, which is a cause of the above, in the molecule.
For example, JP-A-2-235882 discloses 1,1,2,2,3-pentafluoropropane (hereinafter referred to as HFC-245fa), 1,1,1,4,4,4-hexafluorobutane. (Hereinafter referred to as "HFC-356mffm"), and JP-A-3-152160 describes a method for producing a rigid polyurethane foam in which a combustible material such as cyclopentane is applied to a foaming agent. Yes. However, the most excellent heat insulating property of these rigid urethane foams applied to refrigerators and the like is 17 to 20 mw / mK.
[0005]
In refrigerators and the like that do not use substances that cause ozone layer destruction, effectively use resources such as recycling, and reduce power consumption in conjunction with this, the improvement in heat insulation performance for rigid urethane foam, which is a heat insulating material, is the limit. Therefore, as shown in the performance comparison diagram of each heat insulating material in FIG. 1, a technique for applying a vacuum heat insulating panel that can obtain heat insulating performance more than twice that of rigid urethane foam has been proposed.
For example, Japanese Patent Application Laid-Open No. 60-243471 has a heat insulating box in which a PUF pulverized product is put into a synthetic resin bag and vacuum-packed into a board is disposed in a wall. Has proposed a method for installing a vacuum heat insulation panel in which a gap through which the PUF flows is provided on the flange side of the side plate.
[0006]
The shape of many vacuum insulation panels including the above proposal is a plate shape having a thickness of 10 to 20 mm, and is incorporated into the refrigerator wall in the state shown in the cross-sectional view of FIG. 3 through the process shown in FIG. Made in state. For this reason, it is necessary for the core material of the vacuum heat insulating panel to have a predetermined strength in order to satisfy the function of maintaining the vacuum panel shape.
[0007]
On the other hand, in order to improve the heat insulation performance of vacuum insulation panels, use materials that do not easily transfer heat to the constituent materials, reduce the contact area between materials, and control the heat transfer in a plane direction perpendicular to the heat insulation direction. Becomes important. In this way, it is effective in suppressing radiation heat transfer by suppressing the amount of heat that is transferred to the material in the direction of heat insulation (thickness), further interposing a material that suppresses radiant heat transfer, and reducing the size of the gap. .
[0008]
There are many proposals for satisfying the above conditions. For example, Japanese Unexamined Patent Publication No. 60-205164 discloses open-celled rigid urethane foam, Japanese Unexamined Patent Publication No. 60-71881 discloses pearlite powder, and Japanese Unexamined Patent Publication No. Heisei 4-218540. Then, a plate-like molded product obtained by sintering thermoplastic urethane resin powder in a mold, and JP-A-7-96580 discloses a board in which glass long fibers and inorganic fine powder are solidified and held by fibrillated resin fibers, respectively. It is applied as a core material for vacuum insulation panels.
[0009]
Regarding the application of these substances, JP-A-60-208696 and JP-A-58-106292 in which fibers are arranged at right angles to the heat insulating direction to suppress heat transfer in order to achieve improvement in heat insulating performance, Japanese Patent Laid-Open No. Sho 62-13979 in which a metal foil or a metal vapor-deposited film excellent in radiant heat shielding effect is embedded and Japanese Patent Laid-Open Publication No. Sho 63-135694 using PUF mixed with fine powders such as calcium silicate are known.
[0010]
[Problems to be solved by the invention]
Insulation performance (thickness) is achieved by using a material with low thermal conductivity, reducing the contact area between materials, and controlling heat transfer in a plane direction perpendicular to the heat insulation direction. There is a need for a heat insulating mechanism that suppresses heat transfer and radiant heat by suppressing the amount of heat that transmits the material in the direction, and mixing a material with high heat reflection ability to achieve both reduction in radiant heat transfer.
However, the conventional method has a core material structure in which only a part of the heat insulation mechanism necessary for the core material of these vacuum heat insulation panels is applied, and thus the heat insulation performance as a vacuum heat insulation panel is insufficient.
[0011]
In other words, when a particulate material such as calcium silicate or pearlite or a fibrous material typified by glass fiber is directly formed into a plate shape and used as the core material of a vacuum insulation panel, heat is reduced by reducing contact between the materials. Although the suppression of transmission can be achieved, the non-orientation of the material does not suppress the heat transfer that propagates the material in the heat insulation direction, or even if the fibers are oriented, the suppression of radiant heat insulation only affects the heat reflection of the material. The core material structure which fully applied the heat insulation mechanism mentioned above is not necessarily obtained.
[0012]
On the other hand, even if the core material is provided with a metal foil for the purpose of suppressing radiant heat transfer, heat transfer does not attenuate just by spreading in the surface direction, so suppression of heat transfer between substances was obtained. It is not a structure.
[0013]
Moreover, if particles (powder) or fibrous materials are used as they are, it is necessary to devise to improve the compressive strength and to increase the bulk density in order to eliminate deformation of the core material. is there. That is, if these treatments are not performed, they cannot be easily inserted into the vacuum heat insulation panel and have a desired shape, and the volume of the packaging bag after vacuuming is large. In addition, it is difficult to perform as easily as a solidified material. In addition, the packaging material is bent due to the deformation accompanying the volume reduction, and there is a possibility that the vacuum cannot be maintained due to the occurrence of defects such as cracks.
[0014]
This invention has a heat insulation mechanism in which the heat conduction of the constituting material is low, the contact area between the materials is small, the amount of heat transmitted to the material in the heat insulation (thickness) direction is suppressed, and further, heat transfer and radiant heat are suppressed. An object of the present invention is to provide a vacuum insulation panel.
Moreover, it aims at providing the manufacturing method of the core material used for the above vacuum heat insulation panels.
Furthermore, it aims at providing the refrigerator which uses the above vacuum heat insulation panels as a heat insulating material.
[0015]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention is a complex body in which the core material of the vacuum heat insulating panel is formed by stacking a radiant heat shielding member having the shape of the packaging material and having an excellent radiant heat shielding effect on the surface of the glass wool mat. Configured.
Further, the glass wool mat was constructed by depositing glass wool in a surface direction perpendicular to the heat insulation direction.
Moreover, the radiation heat shielding member was comprised with the plate-shaped piece.
The plate-shaped piece was made of mica flakes.
Moreover, the plate-shaped piece was comprised with the metal foil.
The plate-like piece was composed of a plastic film coated with a metal thin film.
Moreover, the adhesion inhibitor which suppresses contact | adherence of a plate-shaped piece was used.
[0016]
Moreover, the core material of a vacuum heat insulation panel arrange | positions a plate-shaped piece on a glass wool mat, the complex production process which produces a complex, and the drying which removes the water | moisture content of the complex obtained by the complex production process Process, an impregnation step of immersing the complex dried in the drying step in a resin solution, and a compression-curing molding step of curing and molding the complex impregnated with the resin in the impregnation step while applying a certain pressure It is manufactured by.
Further, in the complex production step, the slurry liquid in which the plate-like pieces are uniformly dispersed is made up with a glass wool mat.
In the complex production step, the slurry liquid in which the plate-like pieces are uniformly dispersed is dispersed on the glass wool mat.
[0017]
In addition to the plate-like pieces, the plate-like pieces are fixed to each other in the slurry liquid to suppress the adhesion between the plate-like pieces, and the flocculant that makes it easy to bond a part of the binder to the surface of the glass wool mat. And contained.
Further, acrylamide was used as the flocculant. .
Moreover, the cellulose fiber microfibrillated was used for the binder.
A semi-cured thermosetting resin or thermoplastic resin was used as the resin in the impregnation step.
Further, in the compression curing molding process, 4 to 12 layers of the complex body impregnated with the resin in the impregnation process were overlaid and molded.
Further, the applied pressure in the compression hardening molding process was set to 0.7 to 1.5 kg / cm <2>.
[0018]
Moreover, the vacuum heat insulation panel of this invention was arrange | positioned and used as a heat insulating material in the clearance gap formed by fitting the outer box and inner box of a refrigerator.
Further, a hard polyurethane foam was filled in other gaps where no vacuum heat insulation panel was disposed in the gaps.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings and tables.
1. How to create a core material
Below, the preparation method is described by taking as an example a core material in which mica is disposed as a plate-shaped piece that is a radiation heat shielding member on a glass mat.
FIG. 4 is a manufacturing process diagram of a vacuum heat insulating panel. This manufacturing process diagram shows a concept of a method for creating a core material, and details of the method will be described below.
(1) Adjustment of plate-shaped piece (plate-shaped filler)
It is important that the function necessary for the plate-like piece (plate-like filler) which is a radiant heat shielding member in this invention is excellent in heat reflectivity. Therefore, a high-density substance such as a metal or an inorganic substance is preferable. In view of the price reflected from the ease of forming the plate-like piece (flakes), it is most preferable to use aluminum foil or mica.
Moreover, even if it is a plastic film which is a low density substance, the same effect can be acquired if it coat | covers and uses metal thin films, such as aluminum.
Here, an example in which mica is used in the form of flakes will be described. Mica is pulverized to a size of 0.1 mm or more, preferably 5 to 0.5 mm, more preferably about 2 mm, using a pulverizer. It is preferable to apply a high-speed water flow by a water jet to the pulverization at this time because peeling between layers is performed at the same time to obtain a thinner flake-like mica.
[0020]
(2) Preparation of slurry liquid
Mica is dispersed with stirring in water at a concentration of 10 wt% or less, preferably 0.1 to 5 wt%, more preferably 0.5 to 3 wt%. The strength of the stirring at this time is naturally adjusted so that the mica does not settle and the concentration does not become non-uniform, but it is preferably adjusted so that the pulverization of mica does not proceed.
Next, a microfibrillated cellulose fiber (abbreviation: MFC) as a binder is added in an amount of 0.5 to 5 wt%, preferably 1 to 3 wt%, and uniformly dispersed with respect to the input amount of mica. In this case, the input amount is generally a highly viscous slurry in which microfibrillated cellulose fibers are dispersed in water at a concentration of 5 to 10 wt%, and this is converted to the amount of solid dried. It is necessary to. Here, the microfibrillated cellulose fibers were used to immobilize the mica by adding a very small amount, and fibers having a diameter of 1 micron or less were interposed between mica layers. Can be suppressed. In addition, the many minute spaces formed there block the solid heat transfer, and the heat insulation effect of radiant heat can be obtained.
The effect of suppressing the adhesion of mica is more effective by preventing adhesion of mica and forming a space by attaching fine particles, which are adhesion inhibitors, to the mica surface. The size of the fine particles used at this time is preferably 100 microns or less, more preferably 10 microns or less.
Finally, the flocculant is added in an amount of 0.01 to 1 wt%, preferably 0.05 to 0.2 wt%, based on the amount of mica. By introducing the flocculant, the ends of the microfibrillated cellulose fibers are sufficiently bonded to the surface of the mica, and the fixation with the mica or the glass fibers can be further strengthened. As the flocculant, acrylamide is common and most preferred, but polyethyleneimine, chito acid, starch and the like can also be used.
If microfibrillated cellulose fibers are not used, glass mats and fillers such as mica and mica will be insufficiently fixed, and the complex of glass mat and mica will immediately decompose, making handling easier. Only very inferior ones can be obtained.
If no flocculant is used here, the cellulose fibers microfibrillated in the slurry liquid and the bonding between the glass mat and particles such as mica and silica are insufficient, so that the filler cannot be fixed. There arises a problem that only sufficient and non-uniform ones can be obtained.
[0021]
(3) Making up slurry liquid
The glass mat has a thickness of 20 mm or less, preferably 10 mm or less, more preferably 2 to 5 mm when a compression load of 1 kg / cm 2 is applied, and the dimensional change rate with respect to the apparent thickness. Is selected to have a density of 1/20 or more, preferably about 1/5. As shown in FIG. 5, slurry liquid 6 in which mica is dispersed is put on a glass mat placed at the bottom of the cylindrical container 9, and the mica settles and the upper part of the liquid becomes transparent. After leaving still for 1 to 3 minutes, draining from the drain remover 8 at the bottom of the container gives a complex disposed on the glass mat 5 in parallel with the mica. At this time, if drainage is forcibly performed using a vacuum pump, etc., it becomes efficient drainage with little residual moisture in a short time, and there is also a problem that only mica with a small diameter is easily deposited by depositing on the top. Can be prevented.
In the manufacturing process of FIG. 4, the complex was obtained by drawing up the slurry liquid shown in FIG. 5, but the same effect can be obtained by spraying the slurry liquid in which the plate-like pieces are uniformly dispersed on the glass wool mat. .
[0022]
(4) Drying
The obtained complex is left in a high temperature atmosphere to sufficiently remove moisture in order to stabilize the quality in the subsequent steps. The drying temperature at this time is 150 ° C. or less, preferably 100 to 120 ° C., in which the bonding strength between the microfibrillated cellulose fibers and mica and the glass fibers cannot be deteriorated, and is complex by compression. Yankee dryer type that passes between fixing belts and rolls to prevent the sample from dropping due to the initial dry weight after being attached to the surface of a rotating drum that can reduce the bulk density of the body Is effective. In addition to this, it is also effective to use a drying furnace or use it in combination.
[0023]
(5) Impregnation of resin
The dried complex is immersed in a solution of a thermosetting resin, and then pulled up to drop and remove a sufficient excess resin, followed by drying to remove the resin solvent. At this time, the thermosetting resin to be used is most preferably an epoxy resin capable of controlling a semi-cured state that melts at the time of molding, and it is also possible to use polyester or polyimide in addition to this.
It is also effective to use a thermoplastic resin instead of the thermosetting resin.
On the other hand, the amount of the resin to be impregnated is important to prevent the vacuum degassing from being hindered by covering the glass fiber or mica deposition layer surface completely after compression hardening molding, but the deformation due to compression Since it is also necessary to secure an amount that can maintain the range, the range is limited. The amount of the resin to be impregnated is preferably 1 to 20% by weight, more preferably 5 to 10% by weight, based on the weight of the complex. The amount of the resin to be impregnated is adjusted empirically by the resin concentration in the resin liquid and the viscosity of the resin liquid.
[0024]
(6) Compression hardening molding
The complex impregnated with the resin in a semi-cured state is formed into a board shape by being sandwiched between curing plates suitable for the reaction of the resin, that is, temperature and time, and a hot plate holding a certain pressure. The curing conditions at this time vary depending on the type of resin, but in the case of an epoxy resin, it is adjusted so that curing within 120 hours at 120 to 180 ° C., that is, molding is completed. The most important thing in this process is the compression force, and it is necessary to increase the point contact opportunities between the fibers by compression, and solidification needs to be enhanced. On the other hand, if the amount of solid components such as glass, mica and resin increases, the heat insulation performance decreases greatly. Become. Therefore, the range of the compressive load is limited, and is preferably 0.5 to 3 kg / cm @ 2, more preferably 0.8 to 1.5 kg / cm @ 2.
The core material used as a sample was a compression molded product prepared by adjusting a plurality of complex bodies impregnated with a resin in order to obtain a predetermined thickness.
[0025]
2. How to make a vacuum insulation panel
A method for forming a vacuum heat insulation panel will be described with reference to the manufacturing process diagram of FIG.
After inserting the core material into the packaging material heat-sealed in three directions in advance, the internal structure shown in FIG. 7 is heat-sealed in one direction remaining in an atmosphere of a predetermined degree of vacuum using the apparatus shown in FIG. A vacuum insulation panel having
At this time, a thermoplastic resin capable of heat welding is used for the sealing surface of the packaging material, a metal foil such as an aluminum foil for completely blocking the intrusion of outside air is used for the intermediate layer, and the outermost layer. Resin that is resistant to scratches is used. Thus, it is preferable to use a multilayer sheet composed of three or more layers instead of a single film. The sample was adjusted by cutting the core material in order to obtain a predetermined size.
[0026]
2. Evaluation method
The evaluation of the core material was performed for the characteristics including the heat insulation performance and the shape change with the passage of time using the vacuum heat insulation panel obtained as described above.
The sample vacuum insulation panel uses a core material with a thickness adjusted to 20 mm and a surface size adjusted to 180 * 180 mm. The packaging material is nylon, aluminum foil, polyester, and the upper and lower surfaces of the aluminum foil are polyester-based. A 5-layer sheet composed of an adhesive was used. The degree of vacuum in the vacuum heat insulation panel was set to an arbitrary value between 101 and 10-3 Torr, and the heat insulation performance was evaluated by thermal conductivity using “Auto Lambda” manufactured by Eiko Seiki Co., Ltd.
[0027]
【Example】
Example 1.
The results of confirming the effect of improving the heat insulation performance of specific examples of the embodiment of the present invention will be described below.
First, Table 1 shows the composition of main components of a prepreg in which an adhesive is applied to a complex of a glass mat and a plate-like filler.
[0028]
[Table 1]

[0029]
Using the apparatus shown in FIG. 5, the slurry liquid in which MFC and a small amount of acrylamide are dispersed on a glass mat and mica or aluminum foil is added to the glass mat, and the water is removed by forced suction after standing for 5 minutes. The complex of the glass mat and the plate-shaped filler thus prepared was dried in an oven at 100 ° C. for 20 minutes. The glass mat used here was selected to have a thickness of 5 mm under a load of 1 kg / cm @ 2. The flake mica has an average diameter of 3 mm, the aluminum foil has a thickness of 20 μm and is cut to an average diameter of 5 mm, and the silica particles used for adhesion prevention have an average particle diameter of 5 μm.
[0030]
The complex of the glass mat and the plate-like filler obtained by the above method was impregnated with an epoxy resin solution using bisphenol A and epichlorohydrin as resin raw materials and methyl cellosolve as a solvent, and then on the net for about 30 minutes. The excess epoxy resin liquid was dripped by leaving. Thereafter, the surface of the glass mat fiber and the plate-like filler was coated with a semi-cured epoxy resin polymer by removing the solvent and proceeding the reaction by heating and drying in an oven at 125 ° C. for 1 hour. A prepreg was obtained.
[0031]
After the above prepreg is cut to a size of 180 × 180 mm, four sheets are stacked in a flat plate mold having the same size, and are placed in a vacuum atmosphere at 120 ° C. and 10-1 Torr. After standing for 10 minutes, the temperature was raised to 180 ° C. under pressure for 10 minutes, and after further hardening for 40 minutes, the temperature was lowered to near room temperature, and then the core material as a molded product was taken out. At this time, the load applied to the prepreg was 1.2 kg / cm 2 including the weight of the mold.
[0032]
Using the core material obtained by the above method, a vacuum heat insulating panel having an arbitrary degree of vacuum between 101 to 10-3 Torr inside the packaging material was produced, and the thermal conductivity thereof was measured. From the obtained curve of the degree of vacuum and thermal conductivity shown in FIG. 8, the thermal conductivity of the degree of vacuum corresponding to 0.1 Torr and the critical degree of vacuum at which the thermal conductivity rapidly increases are obtained. Is shown in Table 2. On the other hand, deformation due to atmospheric pressure of the vacuum heat insulation panel was confirmed by visual observation.
[0033]
Further, a vacuum heat insulating panel using a glass mat alone corresponding to a conventional product and a continuous rigid polyurethane foam as a core material is shown as Comparative Sample 1 and Comparative Sample 2 as a conventional product. The continuous rigid polyurethane foam shown as the comparative sample 2 has a cell membrane that forms bubbles, and has a structure that allows the air remaining inside to be easily discharged. The vacuum insulation panel used for the material is currently used for refrigerators and the like.
[0034]
[Table 2]

[0035]
From the above results, the vacuum heat insulation panels of Samples 1 to 4 according to this example are heat insulation expressed by thermal conductivity as compared with the glass mat alone and the continuous rigid polyurethane foam shown as comparative samples corresponding to the conventional products. It is clear that the performance has improved significantly.
[0036]
In addition, since the critical vacuum is higher than that of conventional products, it can be said that it has excellent heat resistance performance due to deterioration of vacuum caused by gas entering the vacuum insulation panel system through packaging materials. . Further, it has a sufficient suppression force for deformation with respect to practical use.
[0037]
Although the mechanism for reducing the thermal conductivity of the core material by the above method is not clear, it is presumed that it probably has the following factors. A glass mat is composed of glass fibers with a length of several to several tens of millimeters deposited almost in the plane direction, and has an irregularly entangled structure. It has the characteristic that the space | gap of this can be ensured. As a result, the weight can be secured and the contact portion between the fibers can be suppressed to a very small area, so that heat transfer perpendicular to the surface direction can be suppressed and a heat insulating effect can be obtained.
[0038]
On the other hand, by forming a complex structure that has a structure in which a plate-like substance that has an excellent shielding effect against radiant heat is laminated so that they do not come into direct contact with each other by fine particles etc. Can be secured effectively. In addition, even if the plate-like substance is larger than the heat transfer coefficient of the glass mat, it is an extremely thin layer, so there is almost no influence on the deterioration of the heat insulation effect caused by the heat transmitted through the plate-like substance in the thickness direction. As a result, compared to the case where only the conventional glass mat is used as the core material, the decrease in the amount of radiant heat transfer is significantly greater than the increase in heat transfer due to the arrangement of the plate-like material, so it was used for the vacuum insulation panel. It is estimated that the heat insulation performance improvement can be achieved.
[0039]
Example 2
Next, the effect of using the plate-like filler and fine particles in combination was confirmed. Table 3 shows the composition of the main components.
[0040]
[Table 3]

[0041]
Glass that becomes 5mm thick under a load of 1kg / cm2 with a slurry solution in which silica fine particles and microfibrillated cellulose fibers used to prevent adhesion between mica and mica, which are plate-like fillers, are mixed and dispersed. Sprinkling was carried out on the mat using the apparatus shown in FIG. The flaky mica used here has an average diameter of 3 mm, and the silica particles have an average particle diameter of 10 μm. The glass mat thus obtained is left in an oven under a drying condition of 100 ° C. for 20 minutes to completely remove moisture, and this and the complex of the plate-like filler are bisphenol A and epichlorohydrin as resin raw materials. After impregnation with an epoxy resin solution using methyl cellosolve as a solvent, an excess epoxy resin solution was dropped on the net for about 30 minutes. Thereafter, heating and drying in an oven at 125 ° C. for 1 hour gave a prepreg in which the surface of the glass mat fiber and the plate-like filler was coated with the polymer in a semi-cured state due to the removal of the solvent and the progress of the reaction.
[0042]
After the above prepreg is cut into a size of 180 × 180 mm, four sheets are placed in a flat plate mold having the same size, and left for 10 minutes in a vacuum atmosphere of 10-1 Torr at 120 ° C. Thereafter, the temperature was raised to 180 ° C. in 10 minutes, and after further curing by standing for 40 minutes, the temperature was lowered to near room temperature and then taken out. At this time, the load applied to the prepreg was set to 1.2 kg / cm 2 including the weight of the mold.
[0043]
Using the core material obtained by the above method, the inside of the packaging material was made with a vacuum heat insulation panel at an arbitrary degree of vacuum of 101 to 10-3 Torr, and this was allowed to stand at room temperature for 5 days. From the relationship curve between the degree of vacuum and the thermal conductivity, the thermal conductivity at a degree of vacuum corresponding to 0.1 Torr and the critical degree of vacuum at which the thermal conductivity rapidly increases were obtained. The results are shown in Table 4. In addition, a sample not using silica particles that are fixed between mica layers and serve to prevent the mica, which are plate-like fillers, from sticking to each other, and a case of a composition added with the same weight as mica, respectively Shown in Comparative Sample 4.
[0044]
[Table 4]

[0045]
From the above results, Samples 4 to 7 show the effect of using silica particles, which are fine particles, together with mica, which is a plate-like filler in the core material of the vacuum heat insulating panel according to this example. Although there is no difference in the effect of the silica fine particles in this addition range, the heat insulation performance indicated by the thermal conductivity is not different from the comparative sample 3 using only the mica shown as the comparative example, although the critical vacuum degree is not different. Significantly better. This is considered to be due to the fact that the plate-like fillers are in close contact with each other and act as a single layer, and the effectiveness of providing voids by fixing the fine particles between the layers of the plate-like filler was confirmed.
[0046]
On the other hand, the excessive addition of the plate-like filler can be confirmed in comparison with the comparative sample 4, and there is no difference in the critical vacuum degree due to the addition of 25 parts of silica fine particles, but the heat insulation performance indicated by the thermal conductivity is reduced. Admitted. This is because an excessive amount of silica fine particles agglomerate, and the epoxy resin covers the space created by the aggregation, thereby forming an independent space. Predicted to be caused by a factor that lowers the degree of vacuum in the vacuum insulation panel.
[0047]
Example 3
Next, the effect was confirmed about the load applied at the time of compression molding of a prepreg. Sample 4 shown in Tables 1 and 3 was used as the main component.
The preparation of the prepreg was performed in the same manner as described in Example 1 and Example 2. In other words, a polymer in a semi-cured state by heating and drying after impregnating a complex with flaky mica adhering to the surface placed on a glass mat having a thickness of 5 mm under a load of 1 kg / cm 2 into an epoxy resin solution. A prepreg obtained by coating the surface of mica, which is a fiber and a plate-like filler of glass mat, is obtained. The obtained prepreg is cut into a size of 180 × 180 mm, left in a vacuum mold of 10-1 Torr at 120 ° C. for 10 minutes in a state where four sheets are placed in a flat plate mold, and an arbitrary load is applied. After heating up to 180 ° C. over 10 minutes, holding for an additional 40 minutes and completely curing, the temperature was lowered to near room temperature and taken out to prepare a core material for a vacuum heat insulation panel.
[0048]
At this time, the load applied to the prepreg is 0.7 to 1.5 kg / cm2 including the weight of the mold in a preferable range, and the load applied to the prepreg is 0.5 kg / cm2 which is lower than the preferable range. On the other hand, using a core material having a comparatively high 1.8 kg / cm @ 2 as a comparative sample, a vacuum insulation panel was produced at an arbitrary vacuum degree of 101 to 10-3 Torr inside the packaging material, and the thermal conductivity of this was measured. . From the relationship curve between the degree of vacuum and the thermal conductivity, the thermal conductivity at a vacuum degree equivalent to 0.1 Torr and the critical vacuum degree at which the thermal conductivity suddenly increases are obtained, and the results are compared with Sample 4 and Samples 8-10. Samples 5 to 6 are also shown in Table 5. On the other hand, deformation due to atmospheric pressure was confirmed visually.
[0049]
[Table 5]

[0050]
From the above results, the difference in compression molding load applied to the core material of the vacuum insulation panel is the thermal conductivity due to the influence of the compression molding load in the range of 0.7 to 1.5 kg / cm @ 2 shown in Samples 8 to 10. No difference in critical vacuum. However, although the low compression molding load shown as the comparative sample 5 is equivalent to the thermal conductivity that is an index of the critical vacuum degree and the heat insulation performance, deformation that impairs the designability when mounted in a refrigerator or the like was confirmed.
[0051]
Conversely, although there was no deformation at the high compressive load shown as Comparative Sample 6, it was confirmed that the thermal conductivity was significantly increased to deteriorate the heat insulation performance.
[0052]
As a result, the interval between the fillers becomes smaller than necessary, and even if the excess resin partially fills the gap, a sealed space is formed. As a result, it is presumed that the solvent such as methyl cellosolve or air remaining therein acts as a factor that lowers the degree of vacuum in the vacuum heat insulation panel and deteriorates the thermal conductivity.
[0053]
Example 4
Next, the effect regarding the lamination | stacking at the time of forming with the core material of a vacuum heat insulation panel was confirmed. Sample 4 shown in Tables 1 and 3 was applied as the main component.
In other words, the mica and silica particles are impregnated in epoxy resin liquid with a complex placed on a glass mat with a thickness of 1 to 5 mm under a load of 1 kg / cm2, then heated and dried to make it semi-cured. A prepreg having the surface thereof coated with a polymer is obtained. After cutting this prepreg into 180 × 180 mm, a plurality of sheets are placed in a flat plate mold and left standing for 10 minutes in a vacuum atmosphere of 10-1 Torr under heating at 120 ° C. The core of the vacuum insulation panel is removed by heating it up to 180 ° C over 10 minutes with a load of 1.2 kg / cm2 and then completely curing it by leaving it for 40 minutes and then cooling it down to near room temperature. Made the material.
[0054]
At this time, the number of the prepregs in which the fillers such as glass mat and mica are complexed are stacked in the mold, that is, the number of prepregs stacked is 4 to 12, and the number of samples 4 and 11 to 13 is further increased. 2 cores obtained as sample 7 and comparative sample 8 for 2 sheets less than the preferred number of layers and 19 sheets laminated in excess, and any vacuum with the inside of the packaging material of 101 to 10-3 Torr A vacuum heat insulation panel was prepared at a degree, and its thermal conductivity was measured. From the relationship between the degree of vacuum and the thermal conductivity, the thermal conductivity at a vacuum degree of 0.1 Torr and the critical vacuum degree at which the thermal conductivity rapidly increases were obtained. The results are also shown in Table 6.
[0055]
[Table 6]

[0056]
From the above results, the critical vacuum degree has a tendency to slightly increase with the increase in the number of laminated sheets of 4 to 12 shown in Sample 4 and Samples 11 to 13, and no difference is observed in the thermal conductivity. It was. However, a slight decrease in the thermal conductivity and an obvious decrease in the critical vacuum degree were observed in the comparative sample 7 having a small number of laminated layers. Furthermore, when the number of laminated layers shown as the comparative sample 8 is too large, the critical vacuum degree is slightly excellent, but the thermal conductivity is significantly increased, and it is confirmed that the heat insulating performance is lowered.
[0057]
This is because when the mica, which is a plate-like filler, is molded under vacuum, the solvent or air remaining inside the core material is not easily discharged, and the residual gas becomes a vacuum insulation panel over time. It is predicted that the degree of vacuum in the system was lowered and the thermal conductivity deteriorated.
[0058]
Example 5 FIG.
Next, the operation performance of the refrigerator using the vacuum heat insulating material in the present invention was measured, and the effect was confirmed.
First, using a vacuum insulation panel produced by the same method as Sample 4 shown in Example 1 using a packaging material having an aluminum foil as an intermediate layer, vacuum molding of ABS resin in an outer box obtained by bending a thin steel plate As shown in FIG. 3, a total of six pieces on the ceiling surface, the left and right side surfaces of the freezer compartment, and the refrigeration compartment, and the rear surface are attached to the outer case side in the gap formed by fitting the inner box obtained by Thereafter, rigid urethane foam was filled into the remaining voids by filling, foaming and filling.
[0059]
A refrigerant circuit or the like was arranged using the heat insulation box produced by the above method, and a 400 L class refrigerator was assembled, which was used as a prototype refrigerator. On the other hand, a refrigerator using a heat insulation box produced in the same manner using a vacuum heat insulation panel made of a hard urethane foam having open cells as a core material produced by the same method as comparative sample 2 shown in Example 1 Comparative refrigerator 1, heat insulation box body in which the gap between the inner box and the outer box is filled with rigid urethane foam is referred to as comparative refrigerator 2, and all these refrigerators are consumed in accordance with the power consumption B method measurement method in JIS-C9607. And was also shown in Table 7.
[0060]
[Table 7]

[0061]
From the above results, the refrigerator in which the vacuum heat insulating panel having the core material having the structure in which the flake mica is laminated on the glass mat according to the present invention is compared with the comparative refrigerator 2 using only the hard urethane foam as the heat insulating material. In addition to showing much smaller power consumption, it is superior in comparison with the comparative refrigerator 1 using a vacuum heat insulation panel having a hard urethane foam of a generally used continuous ventilation method as a core material. It turns out that it brings about power consumption.
[0062]
This is based on the fact that the heat insulation performance of the vacuum heat insulation panel of the present invention is significantly superior to that of the conventional vacuum heat insulation panel as shown in Example 1.
[0063]
As described above, the structure of the vacuum heat insulation panel simulating the application to the refrigerator, the thermal conductivity that is an index of the heat insulation characteristics of the embodiment relating to the composition for obtaining the structure and the manufacturing method thereof, and the critical vacuum that can ensure the stable heat insulation performance The degree and the presence or absence of external deformation were evaluated.
As a result, the conventional glass mat and the vacuum heat insulation panel using the open cell rigid polyurethane foam as the core material are laminated with a resin that is laminated and impregnated with a plate-like filler having excellent heat reflection characteristics on the glass mat according to the present invention. By applying the complex structure obtained by solidification to the core material, it can be said that it is suitable for suppressing the deformation of the exterior surface and the excellent heat insulating characteristics when used as a heat insulating material for a refrigerator or the like.
[0064]
Embodiment 2. FIG.
In Embodiment 1 mentioned above, what used a vacuum heat insulation panel for a refrigerator and its door etc. was shown as an example, but it is not limited to a refrigerator, for example, a small refrigerator for vehicles, a prefabricated simple refrigerator, The present invention can also be applied as a part of a product for heat insulation and / or cold insulation, such as a cold car, a pipe, and a heat insulation material for a building, and various modifications can be made without departing from the scope of the invention.
[0065]
【The invention's effect】
As mentioned above, according to the vacuum heat insulation panel of this invention, there exists an effect which reduces radiant heat transfer by the radiant heat shielding member laminated on the glass wool mat.
Further, mica flakes and metal foils can be easily formed into plate-like pieces.
Further, by adding an adhesion inhibitor to the surface of the plate-like piece, the adhesion of the plate-like pieces is suppressed and reduced, and the heat insulation performance is improved.
Further, since the core material of the vacuum heat insulation panel of the present invention is formed by curing the complex impregnated with resin while applying a certain pressure, the packaging material is provided even if the vacuum heat insulation panel is evacuated. The inside does not deform during use.
Moreover, a plate-like piece can be easily arrange | positioned on a glass wool mat only by drawing up the slurry liquid which disperse | distributed the plate-like piece uniformly with the glass wool mat.
Moreover, a plate-shaped piece can be easily arrange | positioned on a glass wool mat only by spraying the slurry liquid containing a plate-shaped piece on glass wool.
In addition, the flocculant and the binding material make it easy to capture the slurry liquid on the glass wool and can be fixed by the binding material, so it can be stably held without being peeled off by resin impregnation, Easy to handle.
The refrigerator using the vacuum heat insulating panel of the present invention as a heat insulating material is a refrigerator in which a heat insulating material is a conventional hard urethane foam only, and further a vacuum heat insulating panel using open cell foamed urethane as a core material is provided. Compared with, it has significantly less power consumption and excellent heat insulation.
Furthermore, since the space | gap with which the clearance gap part was hold | maintained with the hard urethane foam, it fixes firmly and can ensure the external appearance which is not different from the conventional refrigerator.
[Brief description of the drawings]
FIG. 1 is a comparison diagram of heat insulation performance of each heat insulating material.
FIG. 2 is a manufacturing process diagram of a refrigerator equipped with a vacuum heat insulation panel.
FIG. 3 is a layout view of a vacuum heat insulation panel in a refrigerator cross section.
FIG. 4 is a manufacturing process diagram of the vacuum heat insulation panel of the present invention.
FIG. 5 is a conceptual diagram of a papermaking apparatus for disposing a plate-like substance of the present invention on a glass mat.
FIG. 6 is a conceptual diagram of a vacuum heat insulating panel manufacturing apparatus for fusing end sides in a vacuum atmosphere.
FIG. 7 is a cross-sectional view of a vacuum heat insulation panel.
FIG. 8 is a graph showing an example of the relationship between the degree of vacuum and the thermal conductivity.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Outer box of refrigerator, 2 Inner box of refrigerator, 3 Vacuum insulation panel, 4 Hard polyurethane foam, 5 Glass mat, 6 Slurry liquid, 7 Drain liquid, 8 Drain removal (wire net), 9 Cylindrical container, 11 Vacuum Panel molding machine, 14 packaging material, 15 core material.

Claims

A packaging material having a function of forming an outer shell, blocking intrusion of outside air and maintaining a vacuum inside;
On the surface of the grayed Las wool mat, excellent radiation heat shielding effect was laminated radiant heat shielding member made of a plate-shaped piece interposed therebetween inhibits adhesion inhibitor adhesion parallel on the glass wool mat complex A core that is composed of a body, is housed in the packaging material, and retains the shape of the packaging material ;
A vacuum insulation panel characterized by comprising:

2. The vacuum heat insulating panel according to claim 1, wherein the plate-like piece is made of mica flakes.

The vacuum heat insulating panel according to claim 1, wherein the plate-like piece is made of a metal foil.

2. The vacuum heat insulating panel according to claim 1, wherein the plate-like piece is formed by coating a plastic film with a metal thin film.

A plate-like piece mixed in the slurry liquid, a binding material for fixing the plate-like pieces, an adhesion inhibitor for suppressing adhesion between the plate-like pieces, and a part of the binding material on the surface of the glass wool mat. The flocculant that makes it easy to bind is drawn up on the glass wool mat,
By arranging the plate-like pieces on the glass wool mats to form a complex body,
Have a row in the removal of moisture before the Symbol complex body,
The complex body in which Drying was immersed in a solution of the resin,
Method for producing a core material of vacuum insulation panels, which comprises molding the complex body impregnated with tree butter cured while applying a constant pressure.

The steel work complex body, a manufacturing method of the core material of a vacuum insulation panel according to claim 5, characterized in that'll paper making slurry solution uniformly dispersed so the plate-like piece with the glass wool mat.

The steel work complex body, a manufacturing method of the core material of a vacuum insulation panel according to claim 5, characterized in that spraying the plate-shaped piece of slurry were uniformly dispersed on the glass wool mat.

The method for producing a core material for a vacuum heat insulating panel according to claim 5 , wherein the flocculant is acrylamide.

The method for producing a core material for a vacuum heat insulating panel according to claim 5 , wherein the binder is a microfibrillated cellulose fiber.

The method for producing a core material for a vacuum heat insulating panel according to claim 5, wherein the resin into which the complex is immersed is a semi-cured thermosetting resin or a thermoplastic resin.

Molding of the complex body is pre 4-12 layers of the complex body of Bark fat impregnated, method for producing the core material of a vacuum insulation panel according to claim 5, wherein the molding by laminating.

The method for producing a core material for a vacuum heat insulating panel according to claim 5 or 11 , wherein the pressing force is 0.7 to 1.5 kg / cm ² in forming the complex .

An outer box made by bending a thin steel plate,
An inner box made by molding resin,
A gap formed by fitting the outer box and the inner box;
A vacuum heat insulation panel according to claim 1 is provided in the gap and used as a heat insulating material.

The vacuum insulation panel affixed to the inner box or the outer box of the gap portion, rigid polyurethane follower in addition to the gap portion of the gap - claims 1 to 3, characterized in that it is held to fill the arm The refrigerator described.