JPS6214183B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a resin composition for coatings with excellent pigment dispersibility. Conventionally, paints in which pigments are dispersed using vinyl resin or acrylic resin as a color vehicle are known, but when two or more paints of different colors are mixed and painted, the surface of the paint film is Pigment separation and floating (due to the specific gravity of the pigment itself and other factors, when a rubbing test is performed on a paint film, there will be a difference in color between the rubbed test area and other areas)
Such phenomena occurred. This phenomenon is considered to be due to homoaggregation and heteroaggregation of pigments. This heteroaggregation can be prevented to some extent by adding various additives such as surfactants and alcohols during pigment dispersion. However, when a large amount of additives are present in a paint, it brings about unfavorable results in terms of paint film performance, such as repellency and a decrease in water resistance. On the other hand, as a method to prevent homoaggregation, a solution has been found by changing the combination of the conventionally used vehicle and pigment. This method was not universal because it relied on the experience and intuition of paint manufacturers. In order to prevent the agglomeration of pigments as described above, synthetic resins with dispersibility comparable to that of nitrified cotton and oils and fats have been developed, but a sufficient amount has not yet been obtained. The present invention has been made in view of the above-mentioned current situation, and aims to provide a resin composition for paints whose main purpose is to improve the homoaggregation of pigments and improve the dispersibility of pigments. . That is, the present invention provides: (a) acrylic acid or methacrylic acid alkyl ester......46.0 to 99.99% by weight, (b) bis(methacryloxyethyl) phosphate......0.01 to 4.0% by weight, and (c) others The present invention relates to a paint resin composition comprising a copolymer obtained from 0 to 50.0% by weight of a vinyl monomer, a pigment, and a solvent. In other words, one feature of the present invention is that it uses a resin copolymerized with a small amount of a polyfunctional polar monomer. Examples of the alkyl ester of acrylic acid or methacrylic acid [component (a)] used in the present invention include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and (meth)acrylate.
Examples include butyl acrylate, octyl (meth)acrylate, lauryl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and the like, and these may be used alone or as a mixture of two or more. This component is used in a proportion of 46.0 to 99.99% by weight in the copolymer. If the content of this component exceeds 99.99% by weight, the amount of component (b) described later will inevitably decrease, making it impossible to achieve the effects of the present invention. In addition, the component (a) above is 96.0
If the weight percentage is not calculated, the component (c) described later is used in addition to the component (b). Considering the purpose of the present invention and the performance of the coating film, the amount of component (a) used should be at least 46.0% by weight. Further, the bis(methacryloxyethyl) phosphate (component (b)) used in the present invention has the following structural formula. Component (b) is used in a proportion of 0.01 to 4.0% by weight in the copolymer. In the above range, component (b) is 0.01
If it is less than 4% by weight, it is difficult to obtain the effect of preventing pigment homoaggregation, which is the objective of the present invention;
There is a risk of gelation during the production of the copolymer used in excess of 20%, and both are undesirable. Due to the presence of a small amount of the component (b) in the copolymer, when the polar group of the component (b) in the copolymer is adsorbed to the pigment surface, the polymeric resin layer that prevents the pigments from coagulating together is formed. It is thought that it is formed on the surface of the pigment, and as a result, homoaggregation of the pigment is prevented. Furthermore, in the present invention, other vinyl monomers [component (c)] may be used in combination in a proportion of 50% by weight or less in the copolymer, if necessary. The (c) component includes (meth)acrylic acid, maleic anhydride, cyclohexyl (meth)acrylate,
Examples include styrene, vinyltoluene, α-methylstyrene, divinylbenzene, vinyl acetate, (meth)acrylonitrile, glycidyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, etc. These may be used alone or in a mixture of two or more. used as. In particular, in the copolymer of the present invention, a vinyl monomer containing a carboxyl group or an acid anhydride group, such as (meth)acrylic acid or maleic anhydride, is added to improve adhesion to the coated object. It is preferably used in a proportion of 0.1 to 1% by weight in the copolymer. If the amount of the vinyl monomer exceeds 1% by weight, it is not preferable because the water resistance, alkali resistance, etc. of the film decrease. The resin composition of the present invention includes a monomer mixture consisting of component (a), component (b), and optionally component (c),
0.1 to 5% by weight of a polymerization initiator and 50 to 400% by weight, preferably 60 to 150% by weight of a solvent are added to the mixture, and the mixture is constantly heated at 60 to 150°C for about 3 to 12 hours. It can be obtained by a copolymerization reaction according to a method. At this time, monomers, polymerization initiators, etc. may be used separately. Examples of the polymerization initiator include organic peroxides such as benzoyl peroxide, di-tert-butyl peroxide, and methyl isobutyl ketone peroxide; azobisisobutyronitrile;
Examples include azo compounds such as azobisvaleronitrile and azobis2-methylbutyronitrile. In addition, the solvents include aromatic hydrocarbon solvents such as benzene, toluene, and xylene; aliphatic hydrocarbon solvents such as mineral turpentine; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; methyl acetate, ethyl acetate. , ester solvents such as butyl acetate; and ether alcohol solvents such as ethylene glycol ethyl ether and diethylene glycol ethyl ether. These solvents may be used singly or as a mixture of two or more thereof. The molecular weight of the copolymer obtained by the above production method is preferably about 60,000 to 120,000. The resin composition thus obtained is further diluted with a solvent if necessary, and then mixed with a pigment in a conventional manner. Therefore, the resin composition of the present invention mixed with each pigment does not cause any agglomeration of pigments even when two or more types are mixed, and can be used as a coating composition as it is to be applied to metals and other base materials using conventional methods. Even when applied by a painting method, the performance of the film is as good as, if not better than, conventional ones. The pigments used in the composition of the present invention include, for example, organic or inorganic coloring pigments such as titanium oxide, Bengara, iron oxide yellow, and carbon black azo red, or extender pigments, which are generally used for paints. All pigments can be used. Furthermore, the resin composition of the present invention is used as a coating composition by blending various additives, plasticizers, and other resins as necessary. Furthermore, the resin composition of the present invention can contain a polyisocyanate compound or They can be used in combination with amino resins as coating compositions for cold-curing or heat-curing paints, respectively. Hereinafter, the details of the present invention will be explained with reference to Examples.
"Part" or "%" indicates "part by weight" or "% by weight". Example 1 70 parts of methyl methacrylate, 10 parts of ethyl acrylate
part, butyl acrylate 20 parts, maleic anhydride 0.4 parts
parts, bis(methacryloxyethyl) phosphate 0.05 parts, azobisisobutyronitrile 0.8 parts
A mixture of 40 parts of toluene, 10 parts of butyl acetate was charged into a four-necked flask equipped with a stirrer, a thermometer, and a reflux condenser, and reacted at 85±2°C for 8 hours. After the reaction, 50 parts of toluene was added. was added to dilute the resin composition of the present invention. The obtained resin composition was light brown and transparent, and had a color number of 2.
(Gardner), nonvolatile content was 50%, and viscosity was 30 Stoke Poise (hereinafter referred to as sp). Examples 2 to 7 Resin compositions of the present invention were obtained in the same manner as in Example 1 using the formulations shown in Table 1. The solution state, color number, nonvolatile content, and viscosity of the obtained resin composition are also shown in Table 1.

【table】

[Table] Comparative Examples 1 to 3 Compositions of comparative examples were obtained in the same manner as in Example 1 using the formulations shown in Table 2.

[Table] Comparative Test 1 Using each of the resin compositions obtained in Examples 1 to 5 and Comparative Examples 1 and 3, the compositions shown in Table 3 were mixed in a sand grinder to produce white, rust-red, and yellow. Brown, black, and red primary color paints were created. Similarly, using each resin composition obtained in Examples 6 to 7 and Comparative Example 2, primary color paints of white, rust red, tan, black, and red were prepared according to the formulations shown in Table 4. Next, as shown in Table 5, paints were mixed at a ratio of 1 part of each primary color to 10 parts of white paint, and white/rust red/yellow/black = 1/1/2/1.
Paints were prepared by mixing in the ratio of (parts) (the viscosity of each paint was 90-120KU/20℃), and each
% thinner, air spray coating was applied to the entire surface of the slate board, and after drying for 5 minutes, half of the air spray coating was flow coated. After drying for 2 minutes, the flow-coated area was rubbed with a finger and the difference in color was observed. The results are shown in Table 5. In the table, ◎ indicates that there is no difference in color between the air spray area, flow coating area, and rubbing area, △ indicates that the color is slightly different, × indicates that it is different, and XX indicates that there is a significant difference in color. .

【table】

【table】

【table】

[Table] It is clear from the test results table in Table 5 that the paint obtained from the resin composition of the present invention shows no difference in color, while the comparative composition shows no difference in color between the spray-painted area and the sink. Differences in color from the painted areas were observed, particularly in the mixed colors of white/black and white/red rust/yellow/black. Comparative Test 2 A white paint obtained using each of the resin compositions described above was applied onto a glass plate using a 4 mil applicator, drying properties were observed, and then air sprayed onto a slate plate, and the paint was applied with a 4 mil applicator at room temperature. After drying for a week, JIS
Comparative tests were conducted on the alkali resistance, water resistance, weather resistance (Sunshine Weather-Ometer), and adhesion of -K-5654. The results are shown in Table 6.

【table】

[Table] It is clear from the comparative test table in Table 6 that the film performance of the paint obtained from the resin composition of the present invention was superior to, if not inferior to, other similar acrylic resin paints. .

Claims (1)

[Scope of Claims] 1 (a) Acrylic acid or methacrylic acid alkyl ester......46.0 to 99.99% by weight, (b) Bis(methacryloxyethyl) phosphate......0.01 to 4.0% by weight, and (c) A resin composition for coatings comprising a copolymer obtained from 0 to 50.0% by weight of other vinyl monomers, a pigment, and a solvent.