JPH0637597B2 - Matte electrodeposition coating composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a matte electrodeposition coating composition. More specifically, it relates to a matte electrodeposition coating composition obtained by mixing an aqueous electrodeposition coating composition containing a polycarboxylic acid resin, an amino resin and a polyurethane resin as a film forming component with an aqueous dispersion of a specific wax.

(Prior Art) Conventionally, as a paint for forming a matte coating film by electrodeposition coating,
A matte electrodeposition coating composition is known in which an aqueous electrodeposition coating composition containing a polycarboxylic acid resin or an amino resin as a coating film forming component is mixed with a specific wax aqueous dispersion. (Japanese Patent Laid-Open No. 61-14359
However, this matte electrodeposition coating composition can form a uniform matte electrodeposition coating film without uneven gloss, but it is difficult to set the gloss of the coating film to less than 10 at a 60-degree specular gloss value. , A paint capable of forming a lower gloss electrodeposition coating film has been desired.

(Problems to be Solved by the Invention) An object of the present invention is to provide a matte electrodeposition coating composition capable of forming a matte electrodeposition coating film having a low gloss, which is difficult with the conventional paints. .

(Means for Solving Problems) When the present invention is outlined, the matte electrodeposition coating composition according to the present invention comprises (a) a polycarboxylic acid resin, (b) an amino resin,
(C) Polyurethane resin as a coating film forming component, (d)
(A) An aqueous electrodeposition coating composition comprising a basic compound that at least partially neutralizes the carboxyl group of the component, (e) an organic solvent and (f) water, and (g) a solid at room temperature and an electrodeposition coating film. A matte electrodeposition coating composition prepared by mixing an aqueous dispersion of wax having a melting point of not higher than the baking temperature.

The present inventor has paid attention to the point that the gloss of a coating film is reduced by the interaction between the diffuse reflection of light due to the unevenness of the coating film surface and the diffuse reflection of light entering the coating film. The present invention has been completed based on the knowledge that the gloss changes.

The matte electrodeposition coating composition of the present invention was made on the basis of such findings, and by adding a polyurethane resin as a coating film forming component together with an aqueous dispersion of a specific wax, a 60-degree specular gloss can be obtained. The value can be made less than 10, and a uniform matte electrodeposition coating film can be formed, and a coating film excellent in coating performance such as alkali resistance and boiling water resistance and coating appearance can be formed. Is.

The present invention will be described in detail. First, the electrodeposition paint used in the present invention contains (a) a polycarboxylic acid resin, (b) an amino resin, and (c) a polyurethane resin as coating film forming components.

As the polycarboxylic acid resin as the component (a), a saturated or unsaturated alkyd resin and an oil-modified product thereof, a carboxyl group-containing acrylic polymer, a vinyl polymer, an acrylic vinyl copolymer, and the like, or a mixture of two or more of the above. To use.

As the amino resin as the component (b), melamine resin, urea resin, benzoguanamine resin, acetoguanamine resin and the like can be used. In the present invention, one or two of melamine resins such as methanol, ethanol, propanol and butanol is used. Suitable are poorly water-soluble methylolmelamines which are at least partially etherified with one or more monohydric alcohols.

As the polyurethane resin as the component (c), a self-crosslinking type anionic or nonionic aqueous dispersion is used.

The polycarboxylic acid resin of component (a) is (d) one in which at least a part of the carboxyl groups is neutralized with a basic substance, that is, an organic amine or ammonia, so that it can be diluted transparently or as an emulsion with water. .

As the organic amine used for neutralizing the polycarboxylic acid resin, monomethylamine, dimethylamine, trimethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, dimethylaminoethanol, diethylaminoethanol and the like can be used.

It is necessary to improve the physical and chemical properties of a coating film as a thermosetting electrodeposition coating composition by using a polycarboxylic acid resin mixed with an amino resin.

Among the coating film forming components, (a) polycarboxylic acid resin and (b)
The composition ratio with the amino resin is 30 to 30% of the polycarboxylic acid resin.
98% by weight, amino resin 70 to 2% by weight, preferably polycarboxylic acid resin 50 to 90% by weight, amino resin 50 to
It can be used in the range of 10% by weight.

The component (c) is added to an electrodeposition coating solution containing the components (a), (b), (d) and (e), or to the electrodeposition coating obtained by adding the water (f) to it. And stir well to mix.

Examples of the aqueous dispersion of component (g) wax to be added to the electrodeposition paint include montan wax such as montanic acid wax and monotannic acid ester wax, polyolefin wax such as polyethylene wax and oxidized polyethylene wax, and polyolefin such as copolymer polyethylene wax. An acrylic polymer wax such as a copolymer wax, a vinyl ether polymer wax, an acrylic polymer wax, a methacrylic polymer wax, an acrylic / styrene copolymer wax, and an acrylic copolymer wax such as a metal-crosslinked acrylic / styrene copolymer wax can be used.

These waxes are mechanically or emulsified and dispersed in water together with a surfactant.

In the present invention, the wax is a solid which is solid at room temperature and has a melting point not higher than the baking temperature of the electrodeposition coating film, and the water charge of the wax is anionic or nonionic. This is because normal temperature liquid wax cannot be uniformly mixed with the electrodeposition paint and cannot be agitated in the electrodeposition paint film, while wax having a melting point higher than the baking temperature of the electrodeposition paint film is used. The reason is that, when heated and dried, it does not melt, or melts only partly, and in any case, the matte effect cannot be obtained.
Further, when the particle charge of the aqueous dispersion of wax is cationic, the wax does not migrate toward the anode during electrodeposition coating, and the proportion of the wax present in the coating film becomes very small, so that the matte effect cannot be obtained.
In addition, the coating film is also unfavorably roughened.

In the present invention, the electrodeposition coating film having a 60-degree specular gloss value of less than 10 is formed by the synergistic action of the components (c) and (g). The blending amounts of these components are the components (a) and (b). ) At least 5 parts by weight of component (c) (5 PHR; hereinafter referred to as PHR), preferably 1
0-40 PHR is suitable, and the compounding amount of the component (g) is such that an appropriate amount is added to the addition amount of the component (c) according to the desired gloss.

When the compounding amount of the component (c) is less than 5 PHR, a low-gloss coating film intended by the present invention cannot be obtained, while when it exceeds 40 PHR, the coating thickness decreases, the coating appearance and coating performance deteriorate. Therefore, it is not preferable.

The aqueous dispersion of wax is added to an electrodeposition coating stock solution or an electrodeposition coating solution prepared by diluting the stock solution with deionized water, and sufficiently stirred to mix.

The matte electrodeposition coating composition of the present invention has a coating film forming component of 3 to 5
It is adjusted to 0% by weight before use. If desired, the matte electrodeposition coating composition may be mixed with a conventional additive such as a colorant, a surfactant, and other fine powder for matting.

The matte electrodeposition coating composition of the present invention can be produced, for example, by the following method.

In a container equipped with a stirrer and a thermometer, (a) a polycarboxylic acid resin, (b) an amino resin and (e) an organic solvent were put and stirred sufficiently, and then (d) a basic compound was added. Component (a) is made water-dispersible, and then (c) an aqueous dispersion of a polyurethane resin and water are added to prepare an appropriate resin solid content concentration, and then (g) an aqueous dispersion of wax is added. And mix well to finish.

Examples of the organic solvent include methanol, ethanol, n
-Propanol, isopropanol, n-butanol,
Alcohols such as isobutanol, sec-butanol, t-butanol, pentanol, etc., methyl cellosolve, ethyl cellosolve, isopropyl cellosolve,
Cellosolves such as butyl cellosolve and sec-butyl cellosolve are used. The amount of the organic solvent in the electrodeposition coating composition is generally 1 to 5% by weight of the coating film forming component.
Used in the range of.

The matte electrodeposition coating composition of the present invention varies depending on the type of the conductive base material to be coated, but generally the voltage is 15 to 3
An electrodeposition coating film can be formed by applying a direct current of 00 volts for 30 to 300 seconds. After electrodeposition coating, wash with water or heat bake without washing with water. The temperature for heating and baking needs to be at least higher than the melting point of the wax used, but is usually in the range of 150 to 300 ° C.

The target conductive substrate may be any one having conductivity, and the type, size, shape, presence or absence of coloring, etc. are not limited, and examples thereof include iron, copper, aluminum, anodizing treatment or chemical conversion treatment. Aluminized aluminum, and boehmite aluminum can be used.

(Example) Hereinafter, an example will be described in order to more specifically describe the present invention. However, the present invention is not limited to these examples. In addition, the number of parts in the examples means part by weight unless otherwise specified.

Example 1 An electrodeposition coating solution (commercial name: Hanilite) composed of an acrylic polycarboxylic acid resin and a methoxy-butoxy-mixed methylolated melamine as a film-forming component and partially neutralized with triethylamine using methanol and butyl cellosolve as a solvent. AL-7800 Honey Chemical Co., Ltd .: Resin solid content 50% by weight) 160 parts by weight of an aqueous dispersion of anionic polyurethane resin (trade name: Superflex Daiichi Kogyo Co., Ltd .: resin solid content 30% by weight) 20PHR,
An aqueous dispersion of wax showing anionic properties (trade name HYT
ECE-4A manufactured by Toho Kagaku Co., Ltd. (wax solid content: 55% by weight) was added so as to be 17 PHR, deionized water was further added, and they were mixed sufficiently. As a result, a matte electrodeposition coating composition having a solid content of the coating film forming component of 8% by weight was obtained.

Examples 2-5 and Comparative Examples 1-2 All were the same method except that the compounding amounts of the polyurethane resin water dispersion and the wax water dispersion were changed as shown in Table 1 in the method of Example 1. A matte electrodeposition coating composition was prepared.

Experimental Example Example 1 using an aluminum material that has been subjected to normal anodic oxidation treatment
5 to 5 and Comparative Examples 1 and 2 were immersed in the coating compositions of the respective electrodeposition coating compositions, and the aluminum material was used as an anode,
A stainless steel plate is provided as a counter electrode, and electrodeposition coating is performed at a voltage of 180 V for 1 minute, followed by washing with water and then at 180 ° C. for 3 minutes.
It was baked for 0 minutes.

As a result, it was confirmed that the gloss of the electrodeposition coating film was reduced to less than 10 when the coating compositions of the electrodeposition coating composition prepared in Examples 1 to 5 were used. In addition to gloss, the coating thickness, coating appearance, and coating performance were as shown in Table 1.

In addition, the gloss is a high digital variable angle gloss meter (trade name UGV-4
D, manufactured by Suga Test Instruments Co., Ltd.) is a value of 60-degree specular gloss, and the boiling water resistance test of the matte electrodeposition coating film is JIS
K-5400, alkali resistance test is JIS H-860
It carried out according to the test method of 2. However, the boiling water resistance is
The presence or absence of abnormality of the coating film after being immersed in boiling water for 8 hours was determined, and the alkali resistance test was determined by the presence or absence of abnormality of the coating film after being immersed in alkaline aqueous solution for 72 hours.

(Effects of the Invention) As described above, the matte electrodeposition coating composition of the present invention is
The matte electrodeposition coating film having a 60-degree specular gloss value of less than 10 and having excellent coating film appearance and coating film performance can be formed.

Claims (2)

[Claims] 1. A base which comprises (a) a polycarboxylic acid resin, (b) an amino resin and (c) a polyurethane resin as a coating film forming component and at least partially neutralizes a carboxyl group of (d) component (a). Water-based electrodeposition coating composition comprising an organic compound, (e) an organic solvent, and (f) water, and (g) an aqueous dispersion of a wax which is solid at room temperature and has a melting point not higher than the baking temperature of the electrodeposition coating film. Matte electrodeposition coating composition. 2. The matte electrodeposition coating composition according to claim 1, wherein the polyurethane resin is an aqueous dispersion exhibiting anionic or nonionic properties.