JPH02135250A - Water-base paint composition - Google Patents

Abstract

PURPOSE:To provide a water-base paint composition containing a vinylidene chloride resin emulsion produced by the emulsion polymerization of vinylidene chloride, vinyl chloride and other vinyl monomer, etc., having excellent corrosion resistance and suitable as an under-coating paint for the underside of automobile, etc. CONSTITUTION:A vinylidene chloride resin emulsion containing 40-70wt.% of chlorine atom in resin skeleton is produced by the emulsion polymerization of monomer components consisting of (A) 40-80wt.% of vinylidene chloride, (B) 10-60wt.% of vinyl chloride, (C) 5-49.9wt% of other vinyl monomer and (D) 0.1-5wt% of an unsaturated vinyl carboxylic acid. The emulsion is preferably further compounded with 5-50 pts.wt. of a rust-preventing pigment such as zinc chromate or red lead oxide based on 100 pts.wt. of the emulsion in terms of solid.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a water-based paint composition, and more particularly to a water-based paint composition that exhibits excellent corrosion resistance when applied to an 8M board or the like. The water-based paint composition of the present invention is useful as an undercoat paint for fixed-circuit parts, cast parts, forged parts, etc. of automobiles.

[Prior Art] Automobile suspension parts and the like have conventionally been coated with N-coated paint, and corrosion resistance has been imparted by the formed electrodeposition coating. However, for cast or forged parts, it is difficult to apply electrodeposition coating. T! Rust-preventive paints other than II materials are used.

In particular, coatings formed from water-based paints based on vinylidene chloride resin emulsions have an excellent barrier effect that prevents water, oxygen, ions, etc. from permeating.
It has been discovered to be benign and is being considered for use.

For example, in JP-A No. 63-105073M, a tannin substance is mixed into a vinylidene chloride emulsion obtained by emulsion polymerization of vinylidene chloride, a monomer such as an acrylic acid ester, and a vinyl unsaturated carboxylic acid such as acrylic acid. Defense &! ! A coating composition is disclosed. This coating composition exhibits excellent rust prevention performance due to the synergistic effect of the barrier action of vinylidene chloride and the chelation reaction of tannin with iron.

[Problems to be Solved by the Invention] A water-based paint containing a tannin substance is suitable as a rust-preventing paint because it forms a chelate compound with iron and is stabilized. However, according to the research conducted by the present inventors, it has become clear that water-based paints containing tannin substances undergo changes during storage, and the effectiveness of the tannins gradually decreases. In addition, coating films formed from water-based paints using conventional vinylidene chloride resin emulsions as a base resin cannot be said to have sufficient corrosion resistance under severe test conditions. There was a desire to develop a paint that could form a film.

The present invention was made in view of these circumstances, and
The purpose of this invention is to improve the composition of a coating composition using a vinylidene chloride resin emulsion as a base resin without using a tannin substance, so that it has corrosion resistance of -II.

[Means for Solving the Problems] The water-based coating composition of the present invention contains vinylidene chloride 40 to 80%
% by weight, 10-60% by weight of vinyl chloride, 5-49.9% by weight of vinyl monomer, and 0% by weight of vinyl unsaturated carboxylic acid.
．． It is characterized by containing as a resin component a vinylidene chloride resin emulsion, which is formed by emulsion polymerization of a monomer component consisting of 1 to 5% by weight and which contains 40 to 70% by weight of chlorine atoms in the resin skeleton.

In the composition of the resin constituting the vinylidene chloride resin emulsion contained in the aqueous coating composition of the present invention, vinylidene chloride is 40% by weight when the total is 100% by weight.
~80% by weight. The blended amount of vinylidene chloride is 40
When the amount is less than % by weight, the above-mentioned barrier effect is reduced and sufficient corrosion resistance cannot be obtained. On the other hand, if the content exceeds 80% by weight, the resulting emulsion tends to crystallize, resulting in poor film-forming properties. Further, problems may occur in heat resistance.

The greatest feature of the present invention is that vinyl chloride is copolymerized. The present inventors copolymerized various types of nylidene chloride with nylidene chloride and investigated its corrosion resistance. The present invention was completed by discovering that corrosion resistance can be significantly improved by suspending vinyl chloride in a predetermined manner. Vinyl chloride is blended in an amount of 10 to 601%. When the blending amount of vinyl chloride is less than 10% by weight, corrosion resistance decreases and
Even if it exceeds the weight percentage, the corrosion resistance will be poor due to insufficient suspension of vinylidene chloride. A range of 10 to 30% of heavy cypress is particularly preferred.

The content of chlorine atoms in the resin skeleton is 40 to 70% by weight. If the content of chlorine atoms is less than 40% by weight, the barrier effect of the coating film formed will be small and the corrosion resistance will be poor, and if it exceeds 70% by weight, the overall adhesion of the coating film may be insufficient. be.

Note that by blending vinylidene chloride and vinyl chloride in amounts within the above range, the content of chlorine atoms usually falls within this range.

5 to 49.9% by weight of vinyl monomer is blended as another component. When the blending amount of vinyl (thickness) is less than 5% by weight, the adhesion of the coating film becomes insufficient, and when it exceeds 49.9% by weight, the corrosion resistance decreases due to the relative decrease in the blending amount of vinylidene chloride and vinyl chloride. do. The vinyl monomer can be selected from one or more conventionally known monomers such as various acrylic esters, various Nisder methacrylates, vinyl acetate, and styrene.

Moreover, 0.1 to 5% by weight of vinyl unsaturated carboxylic acid is blended in one aqueous coating composition of the present invention.

If this amount is less than 0.1% by weight, film forming properties will be poor,
If it exceeds 5% by weight, the stability of the emulsion particles during the polymerization reaction will be insufficient. Acrylic acid or methacrylic acid is typically used as the vinyl unsaturated carboxylic acid.

A vinylidene chloride resin emulsion, which is one of the components of the aqueous coating composition of the present invention, is obtained by mixing the monomers described above within the above range, adding an emulsifier, and subjecting the mixture to emulsion polymerization. This emulsion polymerization can be carried out in a conventional manner.

The aqueous coating composition of the present invention preferably contains a powder filler. This powder filler is mainly used to improve the physical properties of the coating film and as a jlffi material, and also has the function of preventing water and ions from reaching the material in the coating film and assisting the barrier action of the vinylidene chloride resin. The content of this powdery filler is 10 to 25 parts per 100 parts by weight of the vinylidene chloride resin emulsion in terms of solid content! fi
It is better to make it a department. If the content of M in the powder filler is less than 10 parts by weight, the effect of improving corrosion resistance will not be sufficient, and if it exceeds 250 parts by weight, the resin component will be relatively small, resulting in a decrease in physical properties such as coating film strength. Conversely, corrosion resistance also decreases. This powder filler includes talc,
Extender pigments such as calcium carbonate, barium sulfate, clay, and cinnabar earth are mainly used, but other pigments include inorganic pigments such as titanium oxide, iron oxide, mica, and lead, azo pigments,
Organic pigments such as phthalocyanine, carbon black, etc. (Jf) can also be used.

It is desirable that the aqueous coating composition of the present invention further contains a rust-preventing pigment. By using a rust preventive pigment in the nylidene chloride resin emulsion, the rust preventive performance can be further improved. The amount of this rust-preventive pigment is preferably 5 to 50 parts by weight per 100 parts by weight in terms of solid content of the vinylidene chloride resin emulsion. If the content is less than 5 parts by weight, the effect of the inclusion will be seen, but if the content is more than 50 parts by weight, the effect will be saturated, and the physical properties such as coating film strength and corrosion resistance will decrease due to the relatively small amount of resin component. A decline occurs. As this anti-rust pigment, known anti-rust pigments such as zinc chromate, red lead, calcium lead acid, alinanin, and zinc phosphate can be used. Among these, it is preferable to use non-toxic zinc phosphate.

In addition to the above-mentioned formulations, various coating additives such as anti-sagging agents, antifoaming agents, film-forming aids, and coupling agents can be added to the aqueous coating composition of the present invention.

The water-based coating composition of the present invention is applied to the surface of the object to be coated using a known coating method such as air spraying, and is then maintained at room temperature or under heating for a predetermined period of time to form a coating film with excellent i4 erodibility. be done.

[Operations and Effects of the Invention] The aqueous coating composition of the present invention contains a vinylidene chloride resin emulsion in which vinylidene chloride is copolymerized with vinyl chloride, other vinyl chlorides, and vinyl unsaturated carboxylic acids. The coating film thus formed is significantly more resistant to corrosion than coating films formed from conventional water-based coating compositions that do not copolymerize vinyl chloride. Although the reason for this is not yet clear, it is presumed that the barrier effect of vinylidene chloride resin is further strengthened by the chlorine groups of vinyl chloride.

Therefore, according to the water-based coating composition of the present invention, a coating film having excellent corrosion resistance comparable to that of conventional cationic electrodeposited coatings can be obtained, so that it can be applied to cast parts and forged parts, which have been difficult to coat with conventional cationic electrodeposition coatings. Can be painted to improve corrosion resistance.

EXAMPLES] Hereinafter, the present invention will be specifically explained using examples. In addition, all parts mentioned below mean parts by weight.

(Synthesis of vinylidene chloride resin emulsion) 95 parts of deionized water, 14 parts of nylidene chloride, 1 base cylinder, 4 parts of tabulated vinyl, 0.1 part of sodium alkyl diphenyl ether disulfonate, and 0.2 part of sodium persulfate were reacted under pressure. Pour into a container and hold at 50°C for 4 hours while stirring. Next, sodium argyldiphenyl ether disulfonate 0. 1 part of vinylidene chloride and 16 parts of vinyl chloride were added continuously over 10 hours while stirring while maintaining the temperature at 50°C. Thereafter, 8 parts of ethyl acrylate, 12 parts of acrylic weight and 0.04 part of sodium sulfite were added, and 50 parts of
Hold at ℃ for 10 hours. As a result, emulsion A having a solid content of 60% by weight was obtained.

In addition, emulsions B, C, and D were synthesized using the same synthesis method as above using the monomer composition shown in Table 1, and Ic Q emulsion B contained 50 parts of vinylidene chloride, 15 parts of vinyl chloride, 33 parts of ethyl acrylate, It has a monomer composition of 2 parts of acrylic acid, and together with Emulsion A, it is a vinylidene chloride resin emulsion according to the present invention.

Emulsion C contains the same amount of vinylidene chloride monomer as emulsion A, but does not contain vinylidene chloride monomer. Emulsion D uses the same vinylidene chloride monomer as emulsion B, but does not contain vinyl chloride monomer. That is, Emulsicons C and D are representative examples of emulsions used in conventional water-based paint compositions.

(Example 1) As shown in Table 2, for 100 parts of emulsion A in terms of solid content, 1 part of carbon black, 5 parts of talc,
5 parts of zinc phosphate as a rust preventive pigment, 1 part of paint additive and 200 parts of pure water were added and dispersed with stirring to prepare the aqueous paint composition of Example 1.

This aqueous coating composition was applied by air spray to the surface of a steel plate to a dry film thickness of 40 μm, and dried at room temperature (20° C., hot water content 50%) for 24 hours to form a test plate. The adhesion of the coating film was then evaluated by a substrate test. In addition, a salt spray test was conducted in which crosscuts were cut into the coating film, and salt water was sprayed at 35°C with a concentration of 5 parts, and a water resistance test was conducted in which the coating was immersed in 1 part water at 40°C. The test time was measured as the test time until this occurred or the test time until blisters appeared on the painted surface, whichever was shorter. The results are shown in Table 2. Note that the test was discontinued after 240 hours.

(Example 2) A paint vX14 was prepared in the same manner as in Example 1 except that 50 parts of talc and 10 parts of zinc phosphate were used, and the coating and tests were performed in the same manner. The results are shown in Table 2.

<Example 3> A paint was prepared in the same manner as in Example 1 except that emulsion B was used instead of emulsion A, and 50 parts of talc and 10 parts of zinc phosphate were used. The test was conducted and the results are shown in Table 2.

(Comparative Example 1) A paint was prepared in the same manner as in Example 1 except that Emulsicon C was used instead of the emulsion, and the paint was applied in the same manner.
The test was conducted and the results are shown in Table 2.

(Comparative Example 2) A paint was prepared in the same manner as in Example 2, except that 1Mulsion C was used instead of the emulsion, and the paint was applied in the same manner.
The test was conducted and the results are shown in Table 2.

(Comparative Example 3) A paint was prepared in the same manner as in Example 3 except that Emulsion D was used instead of Emulsion A, and the paint was applied in the same manner.
The test was conducted and the results are shown in Table 2.

(Evaluation) From the test results in Table 2, the test plate formed in the comparative example had a salt spray test result of 48 to 96 hours, but the test plate formed in the example had a salt water spray test result of 120 to 240 hours. In addition, regarding water resistance, blistering occurred after 48 to 120 hours in the comparative example, but no abnormality was observed in the test plate of the example even after 240 hours. These results were used in the examples.
It is clear that this is based on the fact that vinyl chloride is copolymerized in the emulsion.

In addition, compared to the comparison between Example 1 and Actual Flow Example 2, the corrosion resistance was better when there was more talc, and from the comparison between Example 2 and Example 3, it was found that the emulsion A with higher contents of vinylidene chloride and vinyl chloride was used. It can be seen that it has excellent corrosion resistance.

Patent applicant: Aisin Kako Co., Ltd. Agent: Patent attorney 1: Hiroshi Okawa

Claims (1)

[Claims] (1) 40-80% by weight of vinylidene chloride, 10-60% by weight of vinyl chloride, and 5-49.9% by weight of vinyl monomer
A vinylidene chloride resin emulsion containing 40 to 70% by weight of chlorine atoms in the resin skeleton, which is formed by emulsion polymerization of a monomer component consisting of An aqueous paint composition comprising: