JPS6176556A - Water-based inorganic zinc-rich primer - Google Patents

Abstract

PURPOSE:The titled primer that is composed of a vehicle containing aqueous ammonium silicate and a synthetic resin emulsion at a specific ratio and a specific amount of zinc, dust, thus showing good anticorrosive, welding properties, high adhesion to base body and good wet-on-wet coating properties. CONSTITUTION:The objective primer is obtained by mixing (A) a vehicle containing aqueous ammonium silicate of the formula and a synthetic resin emulsion such as epoxy emulsion at a weight ratio of 1:(0.01-0.5) on the solid basis, (B) 40-70wt%, based on the solid components of the coating, of zinc sphere dust of 2-3mu diameter and, when needed, other pigments such as ferrophosphorous. USE:Coating for ships, marine structures, tanks, pipelines, plants and other land structures.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention provides a color vehicle comprising an aqueous solution of ammonium silicate and a synthetic resin emulsion! This invention relates to a water-based inorganic zinc-rich primer containing lIi button powder that has excellent corrosion resistance, weldability, heat resistance, adhesion to substrates, recoatability with top coats, etc.

(Prior Art and Problems to be Solved by the Invention) In general, an inorganic zinc-rich primer using an alkali silicate containing alkali metals such as Li, Na, etc. as a color vehicle is a primer that has particularly excellent anticorrosion properties. It is widely used in ships; offshore structures; and land structures such as tanks, pipelines, and plants. However, when used as a shop primer (sub-rust prevention primer for steel materials), the rust prevention and weldability are good, but (1) the adhesion to the substrate is poor, so the surface to be coated must be cleaned before painting. It must be completely rust-free.

(2) It is difficult to perform airless spray painting.

(3) There is selectivity in recoating with top coat paints, and there is a difficulty in recoating with oil-based paints in particular.

(4) The coating film has poor flexibility.

Due to these drawbacks, it is not actually used as a shop primer.

Therefore, the inventors of the present invention have applied
In Japanese Patent No. 6271, the above (1) is obtained by modifying and treating this alkali silicate with a synthetic resin emulsion.
It has been disclosed that the drawbacks of ) to (4) can be improved. However, it still had the following problems and was still unsatisfactory as a shop primer.

In other words, since the total alkali content in the alkali silicate remains in the coating without being completely removed, the p on the coating surface decreases.
Since H is high and the pH does not drop forever, paints that lack alkali resistance such as oil-based paints are coated over and over again.
This is because the coating may peel off if exposed for a long period of time.

(Means for resolving the problem) The present inventors have solved the essential drawbacks of these conventional alkali silicates and have developed a shop primer that does not cause problems even when overcoated with oil-based paint that lacks alkali resistance. As a result of extensive research, the present invention was completed based on the knowledge that the purpose could be achieved by using ammonium silicate instead of alkali silicate. A color vehicle containing an aqueous solution of ammonium silicate represented by the formula % and a synthetic resin emulsion at a solid content ratio of 1 (0.01 to 0.5), and a color vehicle having a solid content of 40 to 70% by weight based on the solid content of the paint. The present invention relates to an aqueous inorganic zinc-rich primer (hereinafter simply referred to as primer) containing zinc powder. In addition, in the above general formula, m is a positive number, and n is 0 or a positive number.

The ammonium silicate used in the present invention is usually in the form of an aqueous solution, and when zinc powder is mixed with it, it forms a network polymer as shown by the following formula, which coats the object to prevent corrosion. In addition, excess dumbbell acts as a coagulating anode and reacts with carbon dioxide and moisture in the air as shown below to form water-insoluble zinc carbonate, which also has anti-corrosion properties. demonstrate.

In addition, N)14 on the coating film surface reacts with carbon dioxide gas and moisture in the air as shown in the following equation to form a white product and is removed from the system, so the pH of the coating film surface decreases. .

-2 Regarding the degree of decrease in pH of the coating film surface over time.

Compared to conventional alkali silicates, the ammonium silicate of the present invention has a much larger P after coating.
Although H shows a high value like alkali silicate, it rapidly decreases with the passage of time, so even if an oil-based paint is used as a top coat, there will be no problem in its recoatability. In practice, the processing of steel materials involves processing such as fusing, welding and assembling after applying a shop primer, and usually requires a process such as fusing and welding.
Since it takes months or more, the number of days required for the pH of the coated film surface of the primer of the present invention to decrease in one hour does not pose a particular problem.

These are the differences between alkali silicate-based zinc-rich primer and ammonium-silicate-based zinc clinch primer based on the number of days of exposure! This is also clear from Figure 1, which shows the change in ρ11 on the surface of the desert.

Therefore, the present inventors modified ammonium silicate with a synthetic resin 1j:1 emulsion in order to more fully exhibit the characteristics of the zinc clinch primer, which uses ammonium silicate as a legal phase, which has excellent recoatability with top coats. However, when organic properties were added to the paint film, adhesion to the substrate was significantly improved, recoatability with the top coat was further improved, and the increased viscoelasticity of the paint film improved its flexibility. The present inventors have succeeded in taking the present invention one step further by discovering that the workability of airless spray painting also improves.

Synthetic resin emulsions used for modifying ammonium silicate include epoxy emulsions, acrylic emulsions, acrylic-styrene emulsions, styrene-butadiene emulsions, alkyd emulsions, and epoxy ester emulsions, among which epoxy emulsions are most suitable. This is because the epoxy emulsion reacts with ammonium silicate after being uniformly dispersed within the primer.
This is because the paint film becomes more honeyed and has greater cohesive force, which provides the paint film with toughness as a function of a primer.

The blending amount of the synthetic resin emulsion with respect to ammonium silicate is 0.01 to 0.5, preferably 0.05 to 0.3 per 1 of ammonium silicate in terms of solid content ratio.
It is. If it is less than 0.01, adhesion to the substrate and recoatability with the top coat will be reduced, and if it exceeds 0.5, weldability will be markedly reduced and rust prevention will also be reduced.

The zinc powder used in the present invention is spherical with a diameter of 2 to 3 μm or flaky with a diameter of 3 to 15 μm and a thickness of 1 to 2 μm, and these are used alone or in combination.

When spherical and flaky zinc powder is used in combination, the activity is lower than that of spherical zinc powder alone, resulting in better storage stability, and also prevents adhesion to the substrate.
Since metal soap is less likely to be produced by reaction with fatty acids in oil-based paints, recoatability with top coats also improves. ! I! The amount of powder to be mixed is 40 to 7 per solid content of the paint.
0% by weight, preferably 45-65% by weight, 40% by weight
If the content is below 70% by weight, the rust prevention properties tend to deteriorate, and if it exceeds 70% by weight, the properties of melting and cutting are reduced.

Pigments other than zinc powder used in the present invention include:
Phosphorous Sl (Fe, P), titanium oxide, chromium oxide,
iron oxide, zinc chromate, condensed aluminum phosphate,
These include mica and talc.

In this way, in the present invention, the type and amount of zinc dust and other pigments other than zinc dust are carefully selected to further improve the recoatability with the top coat paint. .

The primer of the present invention consists of three components: (a) an aqueous ammonia 11 silicate solution, (b) an aqueous synthetic resin emulsion solution, and (c) a zinc dust mixture of zinc dust and other pigments other than zinc dust. These three components are mixed and painted.6 (Examples and Comparative Examples) The present invention will be specifically explained below using Examples and Comparative Examples.

Examples 1 to 6 Each component (a) and (b) of the primer formulation shown in Table-1
, (c) were blended in the composition ratio shown in the same table to produce Examples 1 to 6.
The primer of the present invention was obtained.

Here, the ammonium silicate aqueous solution of component (-a) and the synthetic resin emulsion aqueous solution of component (b) were obtained by diluting ammonium silicate and synthetic resin emulsion, respectively, with deionized water and stirring until uniform. The zinc dust mixture of component (c) was obtained by mixing zinc dust and other pigments other than the zinc dust in a mixer until uniform, and passing through a 325 mesh sieve.

The primer obtained by mixing these three components has a viscosity of 10
After diluting with water to give a dry film thickness of 2 sec (Ford Cup Nα4/20'C), a sandblasted steel plate was coated with a dry film thickness of 2
It was spray-painted so that it had a thickness of 0μ, and was left to dry at room temperature for 70 minutes. Table 3 shows the coating film performance after being allowed to dry.

Comparative Examples 1 to 3 Each component (a) and (b) of the Brimer formulation shown in Table-2
, (c) were used to obtain brimers of Comparative Examples 1 to 3 according to Examples 1 to 6.

The primers thus obtained were diluted with water in Comparative Example 1.2 and with a solvent (isopropyl alcohol) in Comparative Example 3.
Similarly, the viscosity is 10 seconds (Fort cup size 1α4/20°
C), and then coated according to Examples 1 to 6 and left to dry. The coating film performance is shown in Table 3.

Note-13◎: No starter 17 Note-14 Same as Note-13.

Note - 15 After applying the primer obtained in Examples and Comparative Examples and leaving it at room temperature for 7 days, it was further exposed outdoors for 7 days, and various top coats were applied over it, and it was left at room temperature for 7 days again to be used for the test. did.

Chlorinated rubber-based paints are used as top coats. Searaban Marine Primer, oil-based The system is Dio Nα400. The epoxy system Nipico Marine N-3000, tar Epoxy systems include Balasco Nα400 and Po The urethane type is urethane HB Silva. - (Both products are manufactured by Nippon Oil & Fats Co., Ltd.) (product name) was used.

The test results show that the top coat paint After that, the oily system was exposed on the shore for 12 months. Others were placed in artificial seawater for 12 months. The appearance of the coating film after immersion is shown.

◎: No abnormality observed O: Color, rust, and peeling observed within 3% of the total area △: Swelling, rust and peeling observed within 4-10% of the total area X: Swelling over 11% of the total area , Rust and peeling are observed Note-16 The results of the substrate adhesion test after being treated in the same manner as Note-15 are shown.

@: 100/100 0: (91~99)/100 Δ: (81~90)/100 x: (51~80)/100 Note-17 Steel dimensions 500mmX I OOOmmX6
mmt Oxygen pressure 5kg/am2 Acetylene pressure 0.5kg/cm2 Note-18 Steel dimensions 100mmX I OOOmmX6
mmt Welding rod JIS-D-5026 series welding rod 1 volume J side, left Grass tee 18 Welding speed Rod operation ratio ((beat length) / (consumed welding rod length)) = 1.3 Note-19 Good = Effect of the invention with no peeling in the 5th board visibility test) As is clear from Table 3, the results were compared with the examples in terms of the sturt spray test, outdoor exposure test, fusing properties, weldability, and adhesion to steel plates. There is almost no difference between the examples and both examples show good results. However, in terms of the compatibility of the topcoat paints, the appearance of the coating film is in perfect condition. On the other hand, in all of the Comparative Examples, blistering was observed in the submerged areas in the chlorinated rubber-based products, and JIIv standard was observed after exposure in the oil-based products. moreover,
In the 8'th board adhesion test, adhesion problems were also observed in the chlorinated rubber and oil based systems.

These chlorinated rubber-based and oil-based paints are typical top coats for marine paints, and the poor adhesion with these paints as in the comparative example means that they are completely impractical as shop primers. It is no exaggeration. On the other hand, it is clear that the primers of Examples 1 to 6 according to the present invention completely adhered to any top coat and exhibited extremely excellent performance as a shop primer.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between the number of days of exposure and ρ1 of the coating surface for alkali silicate zinc rich primers and ammonium silicate zinc rich primers.Curve I: Alkali silicate zinc rich primer curve ■ :Ammonium silicate zinc rich primer

Claims (1)

[Claims] An aqueous solution of ammonium silicate represented by the general formula (NH_4)_2O・mSiO_2・nH_2O and a synthetic resin emulsion are blended at a solid content ratio of 1:(0.01 to 0.5). Colorant and 40-70% by weight based on paint solids
(In the above general formula, m is a positive number, and n is 0 or a positive number.)