JP5904662B2 - Cationic electrodeposition coating composition - Google Patents

Description

The present invention relates to a cation-type electrodeposition coating composition, and is mainly applied to a steel sheet with one coat to form an excellent coating film appearance and to form a coating film having excellent corrosion resistance and weather resistance. The present invention relates to a cationic electrodeposition coating composition mainly composed of a resin.

Conventionally, cationic electrodeposition paints can form coatings with excellent corrosion resistance and durability, are water-based paints, and have high paint application efficiency, leading to resource savings, cost savings, and reduced environmental impact. Since then, it has been widely used for automobiles, household equipment, industrial equipment, and the like. More specifically, in order to promote resource saving, process saving, cost saving, etc. in motorcycles, industrial equipment, automobile parts, etc., there is a need for a cationic electrodeposition paint that has a good appearance and can be finished in one coat.

In applications such as the above motorcycles, industrial equipment, and automotive parts, it maintains the corrosion resistance, chemical resistance, and weather resistance that are the characteristics of cationic electrodeposition paints, is a one-coat type, and is gasoline, kerosene, and brake oil. Further, there is a need for a cationic electrodeposition coating that does not cause a decrease in the hardness of the coating film and does not impair the appearance of the coating film even if various other oils adhere to the coating film surface.

In a conventional one-coat type cationic electrodeposition coating, it is customary to use an amino group-containing acrylic resin and an amino group-containing epoxy resin in order to achieve both corrosion resistance, chemical resistance, and weather resistance. In each of Patent Documents 1 to 3, an SP value difference of a certain value or more is ensured between the amino group-containing acrylic resin and the amino group-containing epoxy resin, and the acrylic resin is mainly transferred to the upper layer of the coating film during the baking process. The resin is separated into the lower layer of the coating, and the role of each resin layer is divided, that is, the acrylic resin in the upper layer is weather resistance, the epoxy resin in the lower layer is corrosion resistance, and one coat tries to satisfy both weather resistance and corrosion resistance. Technology.

Also in Patent Document 4, there is basically no difference from Patent Documents 1 to 3 in that two kinds of resins having a SP value difference of a certain value or more are used, but the two kinds of resins are not separated in the paint. As shown above, the amino group-containing acrylic resin and the amino group-containing acrylic modified epoxy resin were used to bring the compatibility of both resins close to a certain degree, and the coating was adjusted to separate the layers with a stable and electrodeposition-coated film. Technology.

In Patent Document 5, in addition to using two types of resins, an amino group-containing acrylic resin having an SP value difference of a certain value or more and an amino group-containing epoxy resin, both resins have a difference in precipitation. Thus, the technique is adjusted so as to change the composition of the coating film obtained depending on the portion of the electrodeposition coating object.

However, in any of these techniques, it is a technique related to an electrodeposition coating using two kinds of resins, an amino group-containing acrylic resin and an amino group-containing epoxy resin, and in these techniques, it is formed after electrodeposition coating and baking. Even if acrylic resin is unevenly distributed in the upper layer of the coating film, if gasoline, kerosene, brake oil, or other various oils adhere to the coating film surface, the hardness of the coating film decreases and more or less is applied. There is a problem that the film appearance is impaired.

JP-A-8-333528 JP 2000-345394 A JP 2001-234116 A JP 2000-178480 A JP 2003-328192 A

  The problem of the present invention is that the above-described decrease in hardness, appearance deterioration, etc. do not occur even when gasoline, kerosene, brake oil or the like adheres to the surface of the coating film in a one-coatable cationic electrodeposition coating composition. And providing an electrodeposition coating composition having both corrosion resistance, chemical resistance, and weather resistance.

That is, the present invention
(A) A vinyl copolymer aqueous resin having a base number of 10 to 85 mgKOH / g-solid, a hydroxyl value of 20 to 200 mgKOH / g-solid, a Tg of 0 to 50 ° C., and a weight average molecular weight of 3,000 to 100,000. , (B) A methacrylic acid ester monomer having a homopolymer Tg of 60 to 170 ° C. and an ester group having 3 to 8 carbon atoms is used as a copolymerization component, and the content of the methacrylic acid ester monomer is 30. -Amino group-containing compound is reacted with a vinyl copolymer resin having a hydroxyl value of 20-200 mg KOH / g-solid and a Tg of 50-120 ° C., and an epoxy resin having an epoxy equivalent of 150-3,000. In the cationic electrodeposition coating composition comprising an amino group-containing epoxy resin obtained as above and (D) a blocked polyisocyanate as essential components, Cationic electrodeposition coating composition in which vinyl copolymer resin (B) is 1 to 40 solid parts by weight with respect to 100 parts by weight of the total of A), (B), (C), and (D) Vinyl copolymer aqueous resin (A), vinyl copolymer resin (B), amino group-containing epoxy resin (C), and blocked polyisocyanate (D) in 100 parts by weight based on the total amount of vinyl copolymer. A cationic electrodeposition coating composition in which the polymerization resin (B) is 4 to 25 solid parts by weight, and in the vinyl copolymer resin (B), the methacrylic acid ester monomer is t-butyl methacrylate and / or cyclohexyl methacrylate. A cationic electrodeposition coating composition, wherein the methacrylic acid ester monomer is t-butyl methacrylate in the vinyl copolymer resin (B). There, vinyl copolymer resin (B) contains an amino group, its base number is a cation type electrodeposition coating composition is 10~85mgKOH / g-solid.

  If the cationic electrodeposition coating composition of the present invention is used, an electrodeposition coating film having excellent corrosion resistance, chemical resistance, durability such as weather resistance, and coating film appearance can be obtained by performing electrodeposition coating once. Even when gasoline, kerosene, brake oil or the like adheres to the surface of the coating film, it does not cause a decrease in hardness, an appearance deterioration, or the like.

Hereinafter, the cationic electrodeposition coating composition of the present invention will be described in detail.
[Vinyl Copolymer Aqueous Resin (A)]
The vinyl copolymer aqueous resin (A) used in the present invention has a base number of 10 to 85 mgKOH / g-solid, a hydroxyl value of 20 to 200 mgKOH / g-solid, a Tg of 0 to 50 ° C., and a weight average molecular weight of 3. , 1,000 to 100,000 vinyl copolymer aqueous resin.

First, the amino group in the vinyl copolymer aqueous resin (A) imparts water dispersibility and electrophoretic properties. As an example of a means for introducing an amino group, an amino group-containing unsaturated monomer is co-polymerized. There are a polymerization method and a method in which a glycidyl group-containing unsaturated monomer is copolymerized and an amino group-containing compound having active hydrogen is further reacted therewith. Examples of amino group-containing unsaturated monomers include dimethylaminoethyl acrylate, diethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dimethylaminopropylacrylamide, diallylamine, and the like. Can be used. Examples of the glycidyl group-containing unsaturated monomer include glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, and the like, and one kind or a mixture of two or more kinds can be used. Examples of amino group-containing compounds to be reacted with glycidyl groups include methylamine, ethylamine, n-propylamine, isopropylamine, monoethanolamine, diethylamine, diethanolamine, N-methylethanolamine, N-ethylethanolamine, ethylenediamine, Examples include diethylenetriamine, hydroxyethylaminoethylamine, ethylaminoethylamine, methylaminopropylamine, dimethylaminopropylamine, and mixtures thereof. The primary amino group is reacted with a ketone in advance to form a block, and then the remaining activity. Hydrogen and an epoxy group may be reacted.

The base number in the vinyl copolymer aqueous resin (A) is designed within a range of 10 to 85 mgKOH / g-solid, more preferably 20 to 75 mgKOH / g-solid. If the base number is less than 10 mgKOH / g-solid, sufficient water dispersibility and electrophoretic properties cannot be ensured, and if it exceeds 85 mgKOH / g-solid, the coating film becomes brittle and the water resistance is lowered to obtain sufficient performance. It's hard to be done.

Next, the hydroxyl group in the aqueous vinyl copolymer resin (A) reacts with the blocked polyisocyanate (D) when the coating film is baked to provide curability. There is a method of copolymerizing the unsaturated monomer containing, for example, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxy Examples thereof include butyl methacrylate, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, and the like, and lactone-modified products thereof. One kind or a mixture of two or more kinds can be used.

  The hydroxyl value in the vinyl copolymer aqueous resin (A) is designed in the range of 20 to 200 mgKOH / g-solid, more preferably 40 to 160 mgKOH / g-solid. When the hydroxyl value is less than 20 mgKOH / g-solid, sufficient curability is not ensured, and when it exceeds 200 mgKOH / g-solid, the coating film becomes brittle, water resistance is lowered, and sufficient performance is hardly obtained.

  Further, in the vinyl copolymer aqueous resin (A), an amino group-containing unsaturated monomer, a glycidyl group-containing unsaturated monomer obtained by reacting an amino group-containing compound, or a unit other than a hydroxyl group-containing unsaturated monomer. As unsaturated monomers, other unsaturated monomers can be copolymerized. For other unsaturated monomers, acrylic acid or methacrylic acid alkyl esters, or other vinyl monomers and amide monomers The body can be used. Specific examples of the compound include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, isobutyl. Acrylic acid such as methacrylate, t-butyl acrylate, t-butyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, heptyl acrylate, heptyl methacrylate or the like Methacrylic acid Alkyl monomers, styrene, α-methylstyrene, vinyl toluene, vinyl acetate, acrylonitrile, methacrylonitrile, and other vinyl monomers, acrylamide, methacrylamide, methylol acrylamide, methylol methacrylamide, methoxymethyl acrylamide, n-butoxymethyl acrylamide, Examples thereof include amide monomers such as diacetone acrylamide and diacetone methacrylamide, ethylene glycol diacrylate, ethylene glycol dimetallate, trimethylolpropane triacrylate, and trimethylolpropane trimethacrylate. These may be used alone or in combination of two or more.

  The content of the other unsaturated monomer in the vinyl copolymer aqueous resin (A) is preferably 40 to 90% by weight, and more preferably 60 to 80% by weight.

  The Tg (glass transition temperature) of the aqueous vinyl copolymer resin (A) is 0 to 50 ° C. When the Tg is lower than 0 ° C., the physical properties, particularly the hardness, of the dried coating film are reduced, and the vinyl copolymer resin ( The compatibility with B) deteriorates, and the stability of the electrodeposition paint decreases. Moreover, when Tg is high, it becomes difficult to obtain an electrodeposition coating film. About the concrete numerical value of Tg of a copolymer resin, it calculates with the formula of the following Fox. Moreover, the range of the weight average molecular weight of the vinyl copolymer aqueous resin (A) is 3,000 to 100,000, preferably 6,000 to 70,000, more preferably 10,000 to 50,000. It is. When the weight average molecular weight is 3,000 or less, the coating film durability is hardly obtained. When the weight average molecular weight is 100,000 or more, the water dispersibility is lowered, and the handleability of the paint tends to be poor.

  The aqueous vinyl copolymer resin (A) as described above is obtained by polymerizing each unsaturated monomer by a known method such as solution polymerization, non-aqueous dispersion polymerization, bulk polymerization, emulsion polymerization, suspension polymerization or the like. However, solution polymerization is particularly preferred, and the reaction temperature is usually 40 to 170 ° C.

  Reaction solvents include n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, t-butyl alcohol, propyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono It is preferable to use a hydrophilic solvent such as butyl ether. Moreover, as a polymerization initiator, well-known things, such as an organic peroxide, an azo compound, ammonium persulfate, potassium persulfate, can be used.

  The proportion of the aqueous vinyl copolymer resin (A) used is an aqueous vinyl copolymer aqueous solution based on 100 parts by weight of the total of (A), (B), (C), and (D), which are constituents of the present invention. The resin (A) is 5 to 80 solids by weight, more preferably 20 to 70 solids by weight, and even more preferably 30 to 60 solids by weight.

[Vinyl copolymer resin (B)]
The vinyl copolymer resin (B) used in the present invention is used together with the vinyl copolymer aqueous resin (A) to increase the hardness of the resulting electrodeposition coating film, improve the scratch resistance, and apply to the coating film surface. Even if gasoline, kerosene, brake oil or other various oils adhere, it is used to prevent the coating film hardness from being lowered and to prevent the appearance of the coating film from being damaged. (Glass transition temperature) is 60 to 170 ° C., the content of the methacrylic acid ester monomer having 3 to 8 carbon atoms in the ester group is 30 to 90% by weight, and the hydroxyl value is 20 to 200 mgKOH / g-solid. Vinyl copolymer resin. Furthermore, it is more preferable that the vinyl copolymer resin (B) contains an amino group in order to obtain a stable resin liquid dispersion, and the means for introducing the amino group include the means described in the vinyl copolymer aqueous resin (A). The same is true, and the base number is preferably 10 to 85 mgKOH / g-solid. However, even when the vinyl copolymer resin (B) does not have an amino group, the performance of the obtained coating film is not adversely affected.

  Examples of the methacrylic acid ester monomer having a homopolymer Tg of 60 to 170 ° C. and an ester group having 3 to 8 carbon atoms include isopropyl methacrylate (81 ° C.), t-butyl methacrylate (118 ° C.), cyclohexyl methacrylate (83 (° C.) and the like, but are not limited to these, and there is no problem even if these are used alone or in combination. Of these, t-butyl methacrylate and / or cyclohexyl methacrylate are preferable, and t-butyl methacrylate is particularly preferable. The content of these monomers in the vinyl copolymer resin (B) is preferably 30 to 90% by weight. If it is less than 30% by weight, the effect of not lowering the hardness of the coating film is not obtained even if oils adhere, and if it exceeds 90% by weight, it is compatible with the aqueous vinyl copolymer resin (A). Decreases, and the stability of the electrodeposition paint decreases.

  For methacrylic acid ester monomers having a Tg of homopolymer of 60 to 170 ° C. and an ester group of 3 to 8 carbon atoms, they are used in common with other unsaturated monomers in the vinyl copolymer aqueous resin (A). The vinyl copolymer resin (B) has a content of 30 to 90% by weight, which occupies a large part of the entire vinyl copolymer resin (B), and the resulting vinyl copolymer resin. (B) gives an effect different from the vinyl copolymer aqueous resin (A) in the present invention.

  The introduction of the hydroxyl group in the vinyl copolymer resin (B) is the same as the means described in the vinyl copolymer aqueous resin (A), and the hydroxyl value in the vinyl copolymer resin (B) is 20 to 200 mgKOH / g-solid. More preferably, it is designed in the range of 40 to 160 mg KOH / g-solid. When the hydroxyl value is less than 20 mgKOH / g-solid, sufficient curability is not ensured, and when it exceeds 200 mgKOH / g-solid, the coating film becomes brittle, water resistance is lowered, and sufficient performance is hardly obtained.

  Furthermore, it can copolymerize using 1 type (s) or 2 or more types of the other unsaturated monomer described in vinyl copolymer aqueous resin (A) as another unsaturated monomer.

  The weight average molecular weight of the vinyl copolymer resin (B) is preferably 3,000 to 50,000, and is preferably smaller than the weight average molecular weight of the aqueous vinyl copolymer resin (A). The Tg of the vinyl copolymer resin (B) is preferably 50 to 120 ° C., and is preferably higher than the Tg of the aqueous vinyl copolymer resin (A). The vinyl copolymer resin (B) has the monomer composition, weight average molecular weight, and Tg as described above, and is preferably produced so as to have a base number. A) It can be obtained by the same production method.

  The ratio of the vinyl copolymer resin (B) used is that of the vinyl copolymer resin (A), (B), (C), and (D), which is a component of the present invention, with respect to 100 parts by weight of the total solid content. B) is 1 to 40 solid parts by weight, more preferably 4 to 25 solid parts by weight, and even more preferably 6 to 20 solid parts by weight.

[Amino group-containing epoxy resin (C)]
The amino group-containing epoxy resin (C) used in the present invention is an amino group-containing epoxy resin obtained by reacting an amino group-containing compound with an epoxy resin having an epoxy equivalent of 150 to 3,000.

The epoxy resin and amino group-containing compound used for the amino group-containing epoxy resin (C) are not particularly specified and used, but are exemplified below.

About an epoxy resin, Preferably it is an epoxy resin which has two epoxy groups in 1 molecule on the average, The epoxy equivalent is 150-3,000, Especially 300-1,500 are preferable.

Specifically, one example is glycidyl ether of polyphenol having two phenolic hydroxyl groups in one molecule, or a polycondensate thereof. Preferred polyphenols include resorcin, hydroquinone, 2,2-bis- (4-hydroxyphenyl) -propane (commonly known as bisphenol A), 4,4′-dihydroxybenzophenone, 1,1-bis- (4-hydroxyphenyl) -methane, 1,1-bis- (4-hydroxyphenyl)- Ethane, 4,4′-dihydroxybiphenyl and the like can be mentioned, and 2,2-bis- (4-hydroxyphenyl) -propane, so-called bisphenol A is particularly preferable.

Other examples include glycidyl ethers of diols having two alcoholic hydroxyl groups in one molecule, or polycondensates thereof. Preferred diols include ethylene glycol, propylene glycol, 1,4-butanediol, 1, Examples include low-molecular diols such as 6-hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol, and 1,4-cyclohexanediol, and oligomer diols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. Without limitation, a mixture of the above epoxy resins is also possible.

  In order to obtain a suitable molecular weight, the epoxy resin is made high molecular weight using a linking agent. Preferred linking agents include the above-mentioned polyphenols or diols, and dicarboxylic acids having two carboxyl groups in one molecule, such as adipic acid, azelaic acid, sebacic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, Examples thereof include isophthalic acid, dimer acid, carboxyl group-containing butadiene polymer and butadiene / acrylonitrile copolymer. Examples of amines include primary amines such as ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, monoethanolamine, dimethylaminopropylamine and diethylaminopropylamine, and diamines such as hexamethylenediamine. A diamine having a secondary amino group can be mentioned. Moreover, chain length extension by polyisocyanate is also possible. A particularly preferred high molecular weight is a method in which the glycidyl ether of the polyphenol or the glycidyl ether of the diol is linked with the polyphenol.

The high molecular weight reaction using the connecting material can be performed in a melt without a solvent, but can also be performed in a system to which a small amount of solvent is added. The solvent is not particularly limited as long as it does not react with the epoxy group. The reaction temperature is suitably 70 to 180 ° C.

  Furthermore, flexibility can be imparted and molecular weight can be adjusted by adding an isocyanate that is half-blocked with a polyol to a hydroxyl group present in the epoxy skeleton.

Examples of the amino group-containing compound to be reacted with the epoxy resin include methylamine, ethylamine, N-propylamine, isopropylamine, monoethanolamine, diethylamine, diethanolamine, N-methylethanolamine, N-ethylethanolamine, ethylenediamine, diethylenetriamine, Hydroxyethylaminoethylamine, ethylaminoethylamine, methylaminopropylamine, dimethylaminopropylamine, etc., or a mixture thereof can be mentioned, and after the primary amino group has been blocked by reacting with a ketone in advance, the remaining active hydrogen and Epoxy groups may be reacted.

The amination reaction in which the epoxy resin and the amino group-containing compound are reacted can be performed in a solvent or a melt without a solvent, and the reaction temperature is suitably 40 to 150 ° C.

The use ratio of the amino group-containing epoxy resin (C) is an amino group-containing epoxy with respect to 100 parts by weight of the total of (A), (B), (C), and (D), which are the constituents of the present invention. The resin (C) is 5 to 40 solid parts by weight, more preferably 8 to 20 solid parts by weight.

A specific method for cationizing a resin containing an amino group constituting the present invention can be carried out by neutralizing the amino group with a protonic acid. Particularly preferred acids include formic acid, lactic acid, and acetic acid. , Propionic acid, citric acid, malic acid, sulfamic acid and the like, or a mixture thereof. The neutralization degree of the acid is preferably 15 to 85%.

[Blocked polyisocyanate (D)]
The blocked polyisocyanate (D) used in the present invention is a reaction product of a polyisocyanate and a blocking agent, and the polyisocyanate is an aromatic or aliphatic (including alicyclic) polyisocyanate. 2,4- or 2,6-tolylene diisocyanate and mixtures thereof, p-phenylene diisocyanate, diphenylmethane-4,4′-diisocyanate, polymethylene polyphenyl isocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 1, 3 or 1,4-bis- (isocyanatomethyl) -cyclohexane, dicyclohexylmethane-4,4′-diisocyanate, bis- (isocyanatomethyl) -norbornane, 3 or 4-isocyanate Tomethyl-1-methylcyclohexyl isocyanate, m- or p-xylylene diisocyanate, m- or p-tetramethylxylylene diisocyanate, a burette modified product of the above isocyanate, an isocyanurate modified product, or an isocyanate group of the above isocyanate Parts of ethylene glycol, propylene glycol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol, 1,4-cyclohexanediol, and other low molecular diols, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, poly Polymers such as oligomeric diols such as lactone diols, trimethylolethane, trimethylolpropane, pentaerythritol, etc. Examples thereof include polyisocyanate linked by riol or a mixture thereof.

On the other hand, the blocking agent includes aliphatic alcohol compounds such as methanol, ethanol, n-butanol and 2-ethylhexanol, cellosolve compounds such as ethylene glycol monomethyl ether and ethylene glycol monobutyl ether, and carbitols such as ethyl carbitol and butyl carbitol. Toll compounds, oxime compounds such as acetone oxime, methyl ethyl ketone oxime and cyclohexanone oxime, lactam compounds such as ε-caprolactam, phenol compounds such as phenol, cresol and xylenol, amino group-containing compounds such as diisopropylamine, pyrazole and triazole, malon Examples include active hydrogen-containing compounds such as acid diethyl ester, acetoacetic acid methyl ester, and acetoacetic acid ethyl ester.

The reaction between the polyisocyanate and the blocking agent can be carried out in a solvent or in a melt without a solvent. Solvents used for the reaction include solvents that do not react with polyisocyanates, such as ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, and isophorone, and aromatics such as benzene, toluene, xylene, chlorobenzene, and nitrobenzene. Examples thereof include hydrocarbons, cyclic ethers such as tetrahydrofuran and dioxane, and hydrogen halides such as chloroform and carbon tetrachloride. Although there is no limitation in particular about reaction temperature, Preferably it is 30-150 degreeC.

  The ratio of the blocked polyisocyanate (D) used is that of the blocked polyisocyanate (A), (B), (C), and (D), which is a constituent of the present invention, with respect to 100 solid parts by weight of the whole. D) is 10 to 50 solids by weight, more preferably 15 to 45 solids by weight, and even more preferably 20 to 40 solids by weight.

  Moreover, a normal coating additive can be added to the cationic electrodeposition coating composition of the present invention as required. Illustrative examples include pigments such as titanium white, carbon black, and bengara, extender pigments such as talc, calcium carbonate, mica, clay, and silica, aluminum molybdate, zinc molybdate, calcium molybdate, zinc phosphomolybdate, and phosphomolybdic acid. Aluminum, zinc phosphate, iron phosphate, aluminum phosphate, calcium phosphate, zinc phosphite, aluminum phosphite, zinc cyanide, zinc oxide, aluminum tripolyphosphate, calcium ferrite, magnesium ferrite, zinc ferrite, bismuth oxide, water Examples include rust preventive pigments such as bismuth oxide, antifoaming agents, repellents, aqueous solvents, and curing catalysts. Moreover, other resin, for example, an acrylic resin, a polyester resin, a urethane resin, and a butadiene resin can be contained.

  The cationic electrodeposition coating composition of the present invention can be applied to the surface of a desired material by known cationic electrodeposition coating. Specifically, the solid content concentration of the paint is preferably 5 to 40% by weight, more preferably 15 to 25% by weight, the pH is adjusted to 5 to 8 according to the amount of acid used, the liquid temperature is 15 to 45 ° C., the load Although the object to be coated can be applied as a cathode under the condition of a voltage of 100 to 450 V, it is not limited to this condition. The coated object to be coated is washed with water and then baked at a temperature of 100 to 220 ° C. for 10 to 30 minutes in a baking oven to obtain a cured coating film. Although there is no restriction | limiting in the coating film thickness obtained, 5-60 micrometers in a cured coating film, Preferably 10-40 micrometers is suitable.

EXAMPLES Next, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these. In addition, unless otherwise indicated, the compounding quantity in a table | surface represents a weight part and weight%.

[Production of aqueous vinyl copolymer resin (A)]
Production Example 1 (Production of resin liquid A1)
A reactor having a stirring device, a thermometer, a monomer dropping device, and a reflux cooling device is prepared. In accordance with the formulation shown in Table 1, (1) and (2) were charged into a reactor, raised to reflux temperature with stirring, and (3) to (8) were mixed uniformly in advance and then added dropwise over 2 hours. . The temperature was maintained at the reflux temperature. (1.5) was added 1.5 hours after the completion of the dropwise addition, and the reaction was further continued at the same temperature for 1.5 hours to obtain a transparent and viscous resin liquid A1. Their solid content (%), Tg (° C.), hydroxyl value (mgKOH / g-solid), base number (mgKOH / g-solid), and weight average molecular weight are also shown in Table 1.

[Production of vinyl copolymer resin (B)]
Production Examples 2 to 7 (Resin Liquids B1 to B6) For Examples and Comparative Examples Production Examples 8 to 9 (Resin Liquids B7 to B8) For Comparative Examples As in the production examples of the vinyl copolymer aqueous resin (A), a stirrer A reaction device having a thermometer, a monomer dropping device, and a reflux cooling device is prepared. In accordance with the formulation shown in Table 2, (1) was charged into a reactor, raised to the reflux temperature with stirring, (2) to (7) were uniformly mixed in advance, and then dropped over 3 hours. The temperature was maintained at the reflux temperature. After 1.5 hours from the end of dropping, (8) is added, and the reaction is further continued at the same temperature for 1.5 hours, and transparent and viscous resin liquids B1 to B6 (for Examples and Comparative Examples) and resin liquid B7 to B8 (for comparative example) were obtained. Their solid content (%), homopolymer Tg of 60 to 170 ° C., and methacrylic acid ester monomer having 3 to 8 carbon atoms of ester group (%), Tg (° C.), hydroxyl value (mgKOH / g-solid), base number (mgKOH / g-solid), and weight average molecular weight are also shown in Table 2.

[Production of amino group-containing epoxy resin (C)]
Production Example 10 (Production of resin liquid C1)
A reaction vessel equipped with a stirrer, a thermometer, and a cooling tube was charged with 1,900 parts of Epototo YD-014 (a bisphenol A-based solid epoxy resin manufactured by Nippon Steel Chemical Co., Ltd.) and 904 parts of propylene glycol monomethyl ether. The mixture was heated to 90 ° C. by stirring and heating. Next, 210 parts of diethanolamine was added while maintaining the same temperature, and the mixture was kept warm for 2 hours to obtain an amino group-containing epoxy resin C1. The solid content was 70%.

[Production of blocked polyisocyanate (D)]
Production Example 11 (Production of resin liquid D1)
In a reaction vessel equipped with a stirrer, a thermometer and a cooling tube, 133 parts of isophorone, 150 parts of toluene, 333 parts of VESTANAT T-1890 / 100 (nurate of isophorone diisocyanate manufactured by Degussa AG), Coronate HX (Nippon Polyurethane Co., Ltd.) 300 parts of hexamethylene diisocyanate nurate produced by the company was charged and the temperature was raised to 60 ° C. Next, 261 parts of methyl ethyl ketone oxime was added dropwise over 1 hour while maintaining 60 ° C., and the mixture was further kept at 60 ° C. for 2 hours. Finally, 100 parts of propylene glycol monomethyl ether was charged to obtain a blocked polyisocyanate D1 having a solid content of 75%.

[Preparation of water-dispersed resin liquid]
According to the formulation in Table 3, deionized water (14) was gradually added to the mixed resin neutralized product of (1) to (13) with good stirring to obtain respective water-dispersed resin liquids.

[Adjustment of pigment paste]
According to the formulation shown in Table 3, (15) to (20) were sufficiently stirred with a dissolver, and then dispersed using a horizontal sand mill until the particle gauge particle size became 10 μm or less to obtain respective pigment pastes.

[Preparation of electrodeposition paint]
The water-dispersed resin liquid and the pigment paste were blended as shown in Table 3 to obtain electrodeposition paints of Examples and Comparative Examples, respectively.

[Preparation of coating test plate and test results]
Using the electrodeposition paint obtained above, a carbon electrode as an anode and a zinc phosphate-treated plate (PB-L3080, 0.8 × 70 × 150 mm manufactured by Nippon Test Panel Co., Ltd.) as a cathode, and a film after baking Electrodeposition coating was performed under the condition that the thickness was 20 μm, and baking was performed at 150 ° C. for 25 minutes. Table 4 shows the properties of the electrodeposition paint and the coating performance test results.

[Description of raw materials]
MA-100 Carbon black ASP # 200 made by Mitsubishi Chemical Corporation Made by Engelhard Corporation
Kaolin (external pigment)
KC-100 Kyodo Yakuhin Co., Ltd. dibutyltin oxide

The evaluation method of emulsifying property and coating film performance is as follows.
(1) Emulsification: The dispersion resin liquid is filtered and determined by the presence or absence of a filtration residue.
○: No filtration residue
×: Many filtration residues (2) Gasoline resistance: After immersion in No. 1 gasoline of JIS-K-2202 at 23 ° C for 2 hours
Observe the paint surface.
○: Almost no difference in gloss and appearance
×: Difference in gloss and appearance (3) Brake oil resistance:
After immersion for 2 hours in brake fluid (DOT4 defined by the Federal Motor Vehicle Safety Standards) at 23 ° C, (i) Observe the coating surface condition.
(Ii) Pencil hardness is measured according to JIS-K-5600-5-4.
(I) Coating state
○: Almost no difference in gloss and appearance
×: Difference in gloss and appearance
(Ii) Pencil hardness
○: Decrease in hardness scale after immersion is 2 or less
X: Decrease in hardness scale after immersion is 3 or more (4) Acid resistance: Observation of the coated surface state after immersion in a 5% sulfuric acid aqueous solution at 20 ° C. for 120 hours.
○: Almost no difference in gloss and appearance
×: Difference in gloss and appearance (5) Alkali resistance: Observation of the coated surface after immersion in a 1% aqueous sodium hydroxide solution at 20 ° C. for 120 hours.
○: Almost no difference in gloss and appearance
X: There is a difference in gloss and appearance. (6) Salt spray resistance test: It was performed according to JIS-Z-2371.
Scratches that reach the substrate on the electrodeposited surface are put with a cutter knife, and the rust width after 500 hours is evaluated.
○: Corrosion width is 3.0 mm or less from cutter knife scratches
X: Corrosion width exceeds 3.0 mm from scratches on cutter knife (7) Accelerated weather resistance test: JIS-D-0205 was performed.
The test coating was fixed in a sunshine carbon weather meter set to the WAN-1S test conditions, and the coated surface state was observed after irradiation for 600 hours.
○: Gloss retention 80% or more
×: Gloss retention less than 80%

According to the present invention, it is possible to carry out one-coat cationic electrodeposition coating on a steel plate or the like, it is possible to form a good coating film appearance, and even when gasoline, kerosene, brake oil, etc. adhere to the coating film surface Further, it is possible to provide a coating film that does not cause a decrease in hardness, deteriorates the appearance, and the like and has both corrosion resistance, chemical resistance, and weather resistance.

Claims (5)

  (A) A vinyl copolymer aqueous resin having a base number of 10 to 85 mgKOH / g-solid, a hydroxyl value of 20 to 200 mgKOH / g-solid, a Tg of 0 to 50 ° C., and a weight average molecular weight of 3,000 to 100,000. , (B) A methacrylic acid ester monomer having a homopolymer Tg of 60 to 170 ° C. and an ester group having 3 to 8 carbon atoms is used as a copolymerization component, and the content of the methacrylic acid ester monomer is 30. -Amino group-containing compound is reacted with a vinyl copolymer resin having a hydroxyl value of 20-200 mg KOH / g-solid and a Tg of 50-120 ° C., and an epoxy resin having an epoxy equivalent of 150-3,000. In the cationic electrodeposition coating composition comprising an amino group-containing epoxy resin obtained as above and (D) a blocked polyisocyanate as essential components, Cationic electrodeposition coating composition in which vinyl copolymer resin (B) is 1 to 40 solid parts by weight with respect to 100 parts by weight of the total of A), (B), (C), and (D) .   The vinyl copolymer resin (A), the vinyl copolymer resin (B), the amino group-containing epoxy resin (C), and the blocked polyisocyanate (D) in total 100 solid parts by weight of vinyl copolymer resin (A) The cationic electrodeposition coating composition according to claim 1, wherein B) is 4 to 25 parts by weight of solid content.   3. The cationic electrodeposition coating composition according to claim 1, wherein in the vinyl copolymer resin (B), the methacrylic acid ester monomer is t-butyl methacrylate and / or cyclohexyl methacrylate. 3. The cationic electrodeposition coating composition according to claim 1, wherein in the vinyl copolymer resin (B), the methacrylic acid ester monomer is t-butyl methacrylate.
What The cationic electrodeposition according to claim 1, 2, 3, or 4, wherein the vinyl copolymer resin (B) contains an amino group and has a base number of 10 to 85 mgKOH / g-solid. Paint composition.