JPS6059268B2 - Cationic electrodeposition paint composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The object of the present invention is to provide a cationic electrodeposition coating composition containing graphite, in particular a coating film with excellent surface smoothness and throwing power among electrodeposition properties. There are things to do.

In contrast to conventional anionic electrodeposition coating compositions, cationic electrodeposition coating compositions have been studied and put into practical use as primer coatings for automobiles, building materials, and the like.

Cationic electrodeposition coating compositions contain polyamino whose main skeleton is an epoxy resin or acrylic resin, which has excellent corrosion resistance, as a vehicle component, and are usually used as an aqueous bath by neutralizing it with an organic acid and making it water-soluble.

The first feature of this cationic electrodeposition coating composition is that it has higher corrosion resistance than anionic electrodeposition coating compositions, even when a special rust preventive agent is used. This is because the main skeleton is made of tough and corrosion-resistant resin such as epoxy resin or acrylic resin. However, a drawback is that the surface smoothness of the coating film (phenomena such as pinholes and repelling) is poor when these resins are used, especially when black or clay-colored formulations are produced.

In order to solve the above-mentioned problem, the present inventor took advantage of the high corrosion resistance of the resin component, based on the current resin component, and investigated various pigment components, and identified graphite. It has been found that by adding it in a certain amount, it is effective in improving the surface smoothness of the coated surface, and is also effective in improving the throwing power of the electrodeposition properties.

That is, in the present invention, in a coating composition that becomes an aqueous bath that can be electrodeposited on a cathode by neutralization with acid, 0.1 to 5 parts of graphite is added to 10 parts of the resin component (solid content).
There is a cationic electrodeposition coating composition characterized in that it contains parts by weight.

In the cationic electrodeposition coating composition used in the present invention, the resin component is a basic water-dispersed resin that should be neutralized with an organic acid or an inorganic acid, and for example, the basic resin skeleton is an epoxy resin, an acrylic resin, Examples include those that use polybutadiene and introduce amino groups for water solubilization, but are not limited to these examples.

It is also effective to use an isocyanate compound in order to lower the baking temperature of the coating film.

A neutralizing agent, pigments (coloring pigments, extender pigments, anti-rust pigments, etc.), hydrophilic solvents, water, additives (such as surfactants), etc. are blended with the above basic resin, and then processed using a conventional method. It is made into paint.
Neutralizing agents for neutralizing and water-solubilizing the above-mentioned basic water-dispersible resin (usually in the form of a solution dissolved in a hydrophilic solvent) include acetic acid, hydroxyl acetic acid, propionic acid, butyric acid, lactic acid, etc. Organic acids and inorganic acids such as phosphoric acid and hydrochloric acid are used.

Further, examples of the pigment include coloring pigments such as carbon black, titanium white, and red iron oxide, other extender pigments, and antirust pigments. For example, cationic electrodeposition paints are used as undercoats, so they come in black, clay, or brown colors, but in the case of black, add 2 to 7 parts by weight of carbon black to 10 parts of resin, and add essential pigments. Add 3 to W parts by weight. In the case of clay color, titanium white is added to black. Hydrophilic solvents include ethanol, n-propanol, isopropanol, n-butanol, Sec-
Alcohol solvents such as butanol, tert-butanol, isobutanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether,
Glycol ether solvents such as ethylene glycol mono-n-propyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, and methyl acetate, ethyl acetate, isopropyl acetate, methyl acetoacetate, ethyl acetoacetate, ethylene glycol monomethyl acetate Ester solvents such as ether, ethylene glycol monoethyl acetate, diethylene glycol monomethyl acetate, diethylene glycol monoethyl acetate, and diethylene glycol monobutyl acetate are used.

In addition, as a surfactant, nonionic and/or
Cationic surfactants are preferred, and nonionic surfactants include polyethylene glycol compounds such as polyethylene glycol alkyl ester, polyethylene glycol alkyl ether, polyethylene glycol alkyl phenyl ether, and polyethylene glycol alkylamide, and polyethylene glycol compounds such as sorbitan aliphatic ester. Hydrolic alcohol partial ester compounds are used, and long-chain aliphatic amine salts, quaternary ammonium salts, and the like are used as cationic surfactants. As described above, conventionally known cationic electrodeposition coating compositions can be used for the present invention. In the present invention, 0.1 to 5 parts by weight, preferably 0.5 to 2.5 parts by weight of graphite is added to the resin component (solid content) of the cationic electrodeposition coating composition per 10 parts by weight. .

If the amount added is less than 0.1 part by weight, the effect on the surface smoothness of the coating film will not be as significant, and if it exceeds 5 parts by weight, fluorescein will occur in the coating film, which will actually reduce the surface smoothness. This will result in a loss. In addition, since graphite is used for paints, it can be either natural or artificial, and can be powdered, lumpy,
Although there are scale-like particles, particles with fine particle size, for example, 60 μm or less, are preferable because they have excellent dispersibility when used as paints.

The above-mentioned basic water-dispersed resin, neutralizing agent, pigment, water,
A cationic electrodeposition coating composition consisting of a hydrophilic solvent, graphite, and if necessary a surfactant is diluted with deionized water to an appropriate solids content (for example, 10 to 15% by weight), then prepared in a predetermined bath. A cured coating with excellent surface smoothness is obtained by electrodepositing the coated object at a bath temperature (e.g. 30°C) and appropriate conditions, pulling it out of the electrodeposition bath, washing it with water, and baking it. membrane can be obtained.

In the present invention, by adding graphite in a specific amount to a cationic electrodeposition paint composition, defects such as pinholes and repellents on the surface of the paint film are prevented from occurring, and the surface smoothness of the paint film is maintained well. Something will happen.

Graphite has traditionally been produced using carbon black, metal powder (
It is well known that, like zinc powder, copper powder, etc., it is added to paints to serve as a conductive powder due to its inherent properties. They found that it has an outstanding effect on improving smoothness, and for example, in the case of carbon black (used as a black pigment in thionic electrodeposition paints), which consists of the same carbon atoms, various amounts of addition were investigated. However, no effect on improving the surface smoothness of the coating film could be observed.

Furthermore, the addition of graphite can further improve the throwing power of the electrodeposition properties compared to conventional cationic electrodeposition paints. As mentioned above, the purpose of the present invention was achieved by adding graphite in a specific amount to a cationic electrodeposition paint, and an intermediate coat and a top coat were applied on the resulting paint film as necessary. It can be used to create an excellent finish coating.

The present invention will be explained below with reference to Examples and Comparative Examples. Parts indicate parts by weight. Example 1 Epoxy polyamino with a resin base number of 80 (Kansai Paint Co., Ltd. product, trade name, equivalent to Elekron NO.9OOO base) was dissolved in a mixture of ethylene glycol monoethyl ether and Sec-butanol, and neutralized with acetic acid to the equivalent amount. Pigments according to the pigment formulations shown in Table 1 were added to 100% of the solid content of the varnish partially neutralized with a concentration of 0.2, and dispersed in a pebble mill for an extended period of time to produce cationic electrodeposition coating compositions 1 to 2.

Deionized water was added to this paint to prepare a bath with a solid content of 12%, a carbon plate was used as an anode, and a zinc phosphate treated steel plate (approximately 150 x 90 x 0.8T1rft (7) SPC) was coated.
A cold-rolled steel plate treated with Nippon Parkerizing Co., Ltd. product name Ponderite #137) was used as a cathode.
Electrodeposition coating was performed by applying electricity for 3 minutes at a bath temperature of 30°C.

The coated board was immediately washed with tap water and then baked at 180°C for three times to prepare a test piece. Table 2 shows the coating film performance test results of the test pieces. We also examined whether repellency was likely to occur on the surface of the paint film by changing the type of test piece. The test results show that the addition of graphite in a specific range is effective in improving the smoothness of the painted surface.

In addition, it is generally said that untreated steel sheets and iron phosphate treated sheets are more likely to cause repulsion than zinc phosphate treated sheets, but in the present invention, any treated sheet will not cause problems in practice. It is recognized that there is no. Example 2 A bisphenol A type epoxy resin (trade name: Epicote 1001, manufactured by Shell Chemical Co., Ltd., 500 fff) having an epoxy equivalent of about 500 was dissolved by heating in 2 (1) parts of cellosolve acetate, and 105 parts of diethanolamine was added at 80°C. The amine value was 90 by reacting at 100'C for 2 hours.
An amine-added epoxy resin is obtained.

Next, tolylene diisocyanate (2,4-TDI=80
%, 2,6-TDI=20%) 174 parts Cellosolve 9
0 part was added dropwise at 60°C over 2 hours, and 264 parts of the obtained blocked isocyanate compound was added to the above amine-added epoxy resin and reacted for 2 hours at 60°C.
A basic resin composition having 52 amines and a solid content of 81% is obtained by reacting for a period of time. 1n part of this has a number average molecular weight of 40
1 part of polyethylene glycol with 00, 33 parts of acetic acid,
Add 114 parts of deionized water to obtain a 40% solids composition. The solid content of this product is 10%, and the pigment according to the pigment composition shown in Table 3 is mixed therein, dispersed in a pebble mill for 2 hours, and then a bath is prepared with a solid content of 12%. Acid zinc treated steel plate (approximately 150 x 90 x 0.8
? An SPC cold-rolled steel sheet (treated with Bonderite #137, a product of Nippon Parkerizing Co., Ltd.) was used as a cathode, and electricity was applied for 3 minutes at a bath temperature of 3 Cf'C to perform electrodeposition coating. Immediately wash the painted board with tap water and then
A test piece was prepared by baking three powders at ℃. Table 3 shows the results of the coating film performance test, which focused on improving the smoothness of the coated surface of the test piece. Test method Painted surface condition: Visually check whether there are any defects such as pinholes or repellents on the painted surface, and whether it is smooth or not. Standard 0: No abnormality, 4: Slight repelling, pinholes, etc. Δ: Significant occurrence of repelling, pinholes, etc. is observed. ×: Painted surface is defective due to repelling, pinholes, and smearing. Impact resistance: DuPont type 112
'' with a weight of 500q from a specified height, and the condition of the coated surface on the front and back sides of the coated plate was determined.

Claims (1)

[Claims] 1 In a coating composition that becomes an aqueous bath that can be electrodeposited on a cathode by neutralization with an acid, the resin component (solid content) 1
1. A cationic electrodeposition coating composition comprising 0.1 to 5 parts by weight of graphite per 0.00 parts by weight.