JP2010144104A - Cationic electrodeposition coating material composition and electrodeposition coating method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrodeposition coating method capable of forming a film having an excellent edge covering property and smoothness. <P>SOLUTION: There is provided a cationic electrodeposition coating material which comprises, as essential components, (a) an amine modified epoxy resin with an amine concentration of ≥1.0 mol/kg, (b) a blocked isocyanate compound and (c) an amorphous silica particle subjected to cation exchange. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a cationic electrodeposition coating composition and an electrodeposition coating method thereof. More specifically, the present invention relates to a cationic electrodeposition coating composition capable of obtaining a coating film excellent in edge cover property and smoothness on an object to be coated and a method of cationic electrodeposition coating.

Electrodeposition coating can be applied to the details even if the object has a complicated shape, and can be applied automatically and continuously, so it has a large and complicated shape such as an automobile body. However, it is widely used as an undercoating method for objects to be coated that requires high rust prevention.
Cationic electrodeposition coating is performed by immersing an object to be coated in a cationic electrodeposition paint as a cathode and applying a voltage. Conventionally, the steel plate occupies most of the objects to be subjected to cationic electrodeposition coating. What surface-treated this steel plate is normally used as a to-be-coated article.

However, the resin component contained in the electrodeposition coating film may flow due to heating during the baking and curing of the electrodeposition coating film. The flow of the resin component causes a decrease in the amount of the coating composition adhering particularly to the end surface portion of the object to be coated, and the occurrence of corrosion and rust proceeds from the end surface portion where the coating composition does not adhere much. In other words, the cationic electrodeposition coating is excellent in throwing power, uniformity of film thickness, etc., but the coating film thickness at the edge of the object to be coated does not increase during heating, and the edge cover property tends to be insufficient. There was a problem with anticorrosion.

As a cationic electrodeposition paint having excellent anticorrosion properties at the edge, a cationic electrodeposition paint obtained by emulsifying two kinds of resins containing a thermosetting acrylic resin and a thermosetting epoxy resin is known. (For example, refer to Patent Document 1) However, this paint is intended to achieve both edge cover properties and weather resistance, and is not sufficient in terms of smoothness.

In addition, as an electrodeposition coating that can provide a cured coating film that has excellent rust prevention properties at the end face of the object and has a good finished appearance, an epoxy resin-amine adduct containing a hydrolyzable alkoxysilane group ( A) and an adduct of a polyisocyanate compound having at least two or more isocyanate groups in one molecule and an oxime compound and / or a compound (B) having at least two or more epoxy groups in one molecule. A cationic electrodeposition coating composition characterized by containing fine particles obtained by water-dispersing the mixture and further intra-particle cross-linking as required in a range of 1 to 35% by mass based on the total resin solid content, A cationic electrodeposition coating composition containing resin fine particles having an average particle size of 0.5 to 10 μm in an amount of 1 to 30% by mass based on the solid content of the coating (for example, Patent Document 2) 3 reference), and the like are known. These coating compositions are a technique of controlling the flowability by increasing the melt viscosity at the time of baking of the coating film by introducing the particle component into the coating film, so when obtaining sufficient edge cover properties, There is a drawback that the smoothness of the coating surface is impaired.

Furthermore, as a coating composition that can be used as an electrodeposition coating, a cationic epoxy resin (A), a crosslinking agent (B), a phosphate group-containing dispersion resin (C), a zinc powder (D), a conductive property A water-based coating composition containing a filler (E), a triazole compound (F), and a phosphate group containing a total of 100 parts by mass of a solid content of a cationic epoxy resin (A) and a crosslinking agent (B) Resin for dispersion (C) 0.1-30 parts by mass, zinc powder (D) 5-200 parts by mass, conductive filler (E) 0.1-100 parts by mass, triazole compound (F) 0.1-30 parts by mass An aqueous coating composition containing a part thereof is known (see, for example, Patent Document 4). However, this coating composition is an aqueous coating composition excellent in coating stability and anticorrosion, and does not improve the edge cover property.

JP 2004-190111 A JP-A-6-287267 JP 2005-200506 A JP 2008-050454 A

As described in the background art above, excellent edge cover properties and smoothness are contradictory coating film performances, and a coating film excellent in both coating film performances has not been obtained.
An object of this invention is to provide the cationic electrodeposition coating composition which can make these two coating-film performances compatible, and the electrodeposition coating method using the same.

As a result of intensive studies to solve the above problems, the present inventors have achieved both excellent edge cover properties and excellent smoothness by a cationic electrodeposition coating composition having a composition under a specific condition. The present inventors have found that a coated film can be obtained, and have completed the present invention.

That is, the present invention includes (a) an amine-modified epoxy resin having an amine concentration of 1.0 mol / kg or more, (b) a blocked isocyanate compound, and (c) cation-exchanged amorphous silica fine particles as essential components. A cationic electrodeposition coating composition is provided.
In the cationic electrodeposition coating composition, the content of the component (c) is 0.3 to 2.0 with respect to the solid content of the total content of the components (a) and (b). Provided is a cationic electrodeposition coating composition having a mass%.
The present invention also provides an electrodeposition coating method comprising electrodeposition coating the above cationic electrodeposition coating composition.

By the electrodeposition coating composition and the electrodeposition coating method of the present invention, a coating film having excellent edge cover properties and smoothness can be formed.

The cationic electrodeposition coating composition used in the present invention is a blocked isocyanate curable electrodeposition coating composition, which contains a resin having a cationic charge and a blocked isocyanate, and is subjected to electrodeposition by utilizing the charge of the resin. It is a type of cationic electrodeposition coating composition that cures when the blocking agent of the blocked isocyanate is dissociated during the curing of the resin and the active hydrogen in the resin component reacts.

As the base resin which is the component (a) of the present invention, an amine-modified epoxy resin having an amine concentration of 1.0 mol / kg or more is used. The amine concentration of the amine-modified epoxy resin is more preferably 1.10 mol / kg or more. When the amine concentration of the amine-modified epoxy resin is less than 1.0 mol / kg, the edge cover property is inferior. The upper limit of the amine concentration of the amine-modified epoxy resin is not particularly limited, but is preferably 2.0 mol / kg or less, and more preferably 1.5 mol / kg or less.

As the epoxy resin in the component (a), any low molecular weight or high molecular weight compound can be used as long as it has an average of more than one glycidyl group per molecule. In particular, polyglycidyl ethers having an average of 2 or more glycidyl groups per molecule are preferred.

Examples of the polyglycidyl ether include polyglycidyl ether of polyphenol. Examples of the polyphenol represented by bisphenol A or bisphenol F include 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane, and 2,2-bis (4 -Hydroxy-3-tert-butylphenyl) propane, 1-5-dihydroxy-3-naphthalene and the like.

As the polyglycidyl ether, a polyglycidyl ether of a cyclic polyol other than polyphenol can also be used. Examples of cyclic polyols other than polyphenols include 1,2-cyclohexanediol, 1,4-cyclohexanediol and 1,2-bis (hydroxymethyl) cyclohexane, which are alicyclic polyols, and hydrogenated bisphenol A and hydrogenated. Bisphenol F prepared.

Examples of other polyglycidyl ethers include polyglycidyl ethers obtained by reacting polyglycidyl ethers of polyalkylene glycols such as polyethylene glycol and polypropylene glycol with monophenol compounds, and phenolic novolac resins or similar polyphenol resins. Examples thereof include polyglycidyl ether and polyglycidyl ether obtained by a reaction between an epoxy compound and a carboxyl terminated butadiene-acrylonitrile copolymer.

  The amine used in the amine-modified epoxy resin is not particularly limited as long as it is an amine that reacts with polyglycidyl ether to form an adduct, for example, primary mono or polyamine, secondary mono or polyamine, or 1, 2 Examples thereof include mixed mono- or polyamines; secondary mono- or polyamines having a ketiminated primary amino group.

Examples of primary mono- and polyamines to be reacted with polyglycidyl ether, secondary mono- and polyamines include mono- and dialkylamines such as methylamine, ethylamine, propylamine, butylamine, dimethylamine, diethylamine, dipropylamine, and methylbutylamine. Mono- and dialkanolamines such as ethanolamine, N-methylethanolamine and diethanolamine; dialkylaminoalkylamines such as dimethylaminoethylamine and diethylaminopropylamine; and N, N-dimethyl-2-hydroxyethyl-propylenediamine It is done.

Examples of mono- and polyamines having a ketiminated primary amino group include N-methylaminopropylamine and a reaction product of diethylenetriamine and methyl isobutyl ketone.

In addition to the amine-modified epoxy resin (a) component, the cationic electrodeposition coating composition of the present invention may be an acrylic, alkyd, polybutadiene, or any other resin that has a functional group that reacts with an isocyanate group. Any resin such as polyester can be used in combination, and two or more of these resins may be used in combination. The content ratio of these resins is preferably 30% by mass or less based on the total amount of the amine-modified epoxy resin and other resins.

Next, the blocked isocyanate compound used as the curing agent for component (b) may be a self-crosslinking type contained in the molecule of the base resin, or an external crosslinking type contained outside the base resin. In both cases of the self-crosslinking type and the external crosslinking type, the isocyanate compound and the blocking agent used for the production of the blocked isocyanate compound to be used are the polyisocyanate compounds and the blocks dissociated by heating at 100 to 200 ° C. The agent is suitable.

Examples of the polyisocyanate compound include tolylene diisocyanate, xylylene diisocyanate, tetramethylene diisocyanate, 4,4′-diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, p-phenylene diisocyanate, 3,3′-dimethyldiphenyl 4,4 ′. Aromatic, aliphatic and alicyclic polyisocyanates such as diisocyanate, 1,5-naphthalene diisocyanate, 1,6-hexane diisocyanate, lysine diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, norbornane diisocyanate Compounds.

Polyisocyanate compounds include, for example, polyols including ethylene glycol, propylene glycol, tetramethylene glycol, trimethylolpropane, polyethylene glycol, polypropylene glycol, polycaprolactone, polycarbonate polyol, adipic acid, phthalic acid, azelaic acid, sebacin It may be a polyisocyanate compound having an isocyanate at the terminal by reacting with a carboxylic acid such as acid or maleic acid.

Examples of the blocking agent include aliphatic alcohols such as methanol, ethanol, n-butanol and 2-ethylhexanol, oximes such as methyl ethyl ketoxime, diacetketoxime, butanone-2-oxime and cyclohexanone oxime, phenol, p- Cresol, phenols such as p-tertiary butylphenol, lactams such as ε-caprolactam, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether, propylene glycol monobutyl ether, diethylene glycol monomethyl ether, ethylene glycol monophenyl ether, Propylene glycol monophenyl ether, butyl diglycol (= diethylene glycol mono Chirueteru) ether alcohols such as, aromatic alkyl alcohols such as phenyl carbitol. In particular, caprolactams and oximes are suitable for paints that require low-temperature curability.

A dissociation catalyst can also be used for dissociating the blocking agent of the blocked polyisocyanate as the curing agent. As the dissociation catalyst, organic tin compounds such as dibutyltin laurate, dibutyltin oxide and dioctyltin, amines such as N-methylmorpholine, and metal salts such as zinc, cobalt, bismuth and zirconium can be used. The concentration of the catalyst is usually preferably 0.1 to 5% by mass with respect to the solid content of the coating film in the cationic electrodeposition coating.

In the blocked isocyanate-containing cationic electrodeposition coating composition, the self-crosslinking type blocked isocyanate compound having the blocked isocyanate in the base resin can be produced by a conventionally known method, for example, a partially blocked polyisocyanate compound. It can be produced by introducing blocked isocyanate into the base resin by a method of reacting free isocyanate in the isocyanate compound with active hydrogen in the base resin. Moreover, as an external bridge | crosslinking type block isocyanate compound, what blocked all the isocyanates of the said polyisocyanate is mentioned.

The solid content mass ratio (amine-modified epoxy resin / curing agent) of the component (a) amine-modified epoxy resin and the component (b) blocked isocyanate compound is preferably 90/10 to 50/50, more preferably 80. / 20 to 65/35.

In the present invention, the cation-exchanged amorphous silica fine particles of component (c) can not only simply increase the melt viscosity of the coating film but also develop a structural viscosity.
Since the cation-exchanged amorphous silica fine particles of component (c) have a special surface, they have excellent affinity with the component (a) amine-modified epoxy resin. The interaction with the polar group of the amine-modified epoxy resin exhibits a structural viscosity behavior in which the viscosity at the low shear rate is higher than the viscosity at the high shear rate. A coating film exhibiting this structural viscosity behavior effectively works to prevent squeezing of the edge portion without increasing the melt viscosity more than necessary and suppressing fluidity, and has excellent edge cover properties.

Examples of the cation with which the amorphous silica fine particles are ion-exchanged include calcium ion and magnesium ion, and calcium ion is particularly preferable.
For example, the amorphous silica fine particles subjected to calcium ion exchange include non-toxic rust preventive pigments obtained by ion exchange of calcium ions in porous silica gel powder. It is considered that H + that has passed through the coating film ion-exchanges with Ca + in the coating film, and the released Ca + protects the metal surface and exhibits a rust preventive action. Commercially available products of calcium ion-exchanged amorphous silica fine particles include Shieldex 303, AC-3, AC-5 (manufactured by W. RGlace & Co), Shielddex (manufactured by Fuji Silysia), and the like.

The average particle size of the cation-exchanged amorphous silica fine particles is preferably 1 to 10 μm, and more preferably 2 to 5 μm.
The cation content in the cation-exchanged amorphous silica fine particles is preferably 1 to 20% by mass, and more preferably 3 to 10% by mass.

  The content of the component (c) used in the present invention is preferably 0.3 to 2.0% by mass, more preferably 0.8%, based on the solid content of the total content of the components (a) and (b). It is 5-1.8 mass%. When the content of the component (c) is less than 0.3 mass% with respect to the solid content of the total content of the components (a) and (b), the edge cover property is not sufficient, and 2.0 mass When it exceeds%, smoothness deteriorates.

A pigment can be blended in the cationic electrodeposition coating composition of the present invention as necessary.
The pigment is not particularly limited as long as it is a pigment that is usually used in electrodeposition paints. For example, coloring pigments such as titanium oxide, bengara, carbon black, and yellow iron oxide; extender pigments such as clay, talc, mica, and calcium carbonate Rust preventive pigments such as zinc phosphomolybdate, aluminum phosphate, and aluminum polyphosphate;

In the cationic electrodeposition coating composition of the present invention, a pigment dispersing resin intended for pigment dispersion can be used. There is no restriction as a resin for dispersing the pigment, and a resin having a cationic charge can be used. However, a resin with improved dispersibility of the pigment is preferable. For example, an epoxy quaternary ammonium type, a tertiary amine type, an acrylic quaternary type Ammonium type resins are preferred.

The cationic electrodeposition coating composition of the present invention is usually carried out using a ball mill, a sand mill, a super mill, a continuous disperser or the like until the pigment is crushed to a desired size, sufficiently wet, and dispersed to produce a pigment paste, In making the resin aqueous, an amount of water sufficient to form a continuous water phase is blended, and an aqueous solution or emulsion is produced using a stirrer, an emulsifier, or the like.

The cationic electrodeposition coating composition of the present invention is adjusted so that the solid content of the coating is generally 5 to 35% by mass and the pH is 5.0 to 6.5 by adding an aqueous medium such as water if necessary. Thus, it is preferable to perform electrodeposition coating.
As an electrodeposition coating method using the cationic electrodeposition coating composition of the present invention, for example, the coating temperature is 25 to 35 ° C., the voltage is 40 to 400 V, and the film thickness of the cured coating film is in the range of 10 to 40 μm. A method of painting is preferred. Furthermore, the range of 100-200 degreeC is suitable for the baking temperature at the time of hardening of a coating film.

In the present invention, it is particularly preferable that the wet coating film of the cationic electrodeposition coating composition has a viscosity at 120 ° C. and a shear rate of 5S- ¹ at least 10 times the viscosity at a shear rate of 50S- ¹ It is more preferably 10.5 times or more. When this viscosity ratio is less than 10 times, it is difficult to achieve both edge cover properties and smoothness. There is no upper limit for this viscosity ratio, and the higher the better.
Moreover, it is preferable to adjust so that the viscosity at 120 degreeC and shear rate 5S- ¹ time may become 100 Pa * S or less, and it is more preferable to adjust so that it may become 90 Pa * S or less. When it exceeds 100 Pa · S, it is difficult to obtain smoothness.

The cationic electrodeposition coating composition of the present invention is a conductive substrate, for example, a metal such as cold rolled steel, hot rolled steel, aluminum, magnesium, magnesium alloy, and surface treatment of these substrates as necessary. For example, it can be applied to a desired one according to the required quality, such as a zinc phosphate treatment, an iron phosphate treatment, a chromate treatment, an organic film treatment or the like.

There are no particular restrictions on the intermediate coating and top coating applied on the electrodeposition coating film of the present invention, and any commonly used intermediate coating or top coating can be applied.

Next, although the Example of this invention is described in detail, this invention is not limited to these description. In each example, all the descriptions regarding “parts” and “%” are “parts by mass” or “% by mass” unless otherwise specified.

Production Example 1 Production of pigment dispersing resin 2598 parts of bisphenol-A-diglycidyl ether having an epoxy equivalent weight of 188, 787 parts of bisphenol A, 603 parts of dodecylphenol and 206 parts of butyl glycol were added to 4 parts of triphenylphosphine. In the presence, it was reacted at 130 ° C. to an epoxy equivalent of 856. Next, while cooling, 849 parts of butyl glycol and 1534 parts of polypropylene glycol diglycidyl ether (manufactured by Dow Chemical, trade name “DER732”) were added, and 266 parts of 2,2-aminoethoxyethanol and N, at 90 ° C. N-dimethylaminopropylamine (212 parts) was added and reacted. After 2 hours, after the viscosity became constant, diluted with 1512 parts of butyl glycol, neutralized with 201 parts of glacial acetic acid, and further added with 1228 parts of deionized water, an aqueous pigment dispersion resin solution having a solid content of 60% was obtained. Created.

Production Example 2 Production of curing agent A reactor equipped with a stirrer, reflux condenser, internal temperature controller and inert gas supply pipe was charged with polymethylene polyphenyl polyisocyanate (trade name “Luprant, manufactured by BASF AG). ]) 10552 parts were charged under a nitrogen atmosphere. To this, 18 parts of dibutyltin dilaurate was added, and 9498 parts of butyl diglycol was added dropwise little by little with occasional cooling so that the reaction temperature did not exceed 60 ° C. After the addition was complete, the temperature was maintained at 60 ° C. for an additional 60 minutes and dissolved in 7768 parts of methyl isobutyl ketone, after which 933 parts of trimethylolpropane were added at a rate such that the product did not exceed 100 ° C. After completion of the addition, the reaction was further continued for 60 minutes to confirm that no free NCO groups were detected. The mixture was cooled to 65 ° C. and simultaneously diluted with 965 parts of n-butanol and 267 parts of methyl isobutyl ketone to obtain a blocked polyisocyanate compound having a solid content of 70%. The dissociation temperature of the blocked isocyanate compound using butyl diglycol as a blocking agent was 170 ° C.

Production Example 3 Production of amine-modified epoxy resin A Epoxy resin based on bisphenol A having an epoxy equivalent of 188 in a reactor equipped with a stirrer, reflux condenser, internal thermometer and inert gas supply pipe. 6150 parts of (bisphenol-A-diglycidyl ether) were heated to 125 ° C. under a nitrogen atmosphere together with 1400 parts of bisphenol A, 335 parts of dodecylphenol, 470 parts of p-cresol and 441 parts of xylene, and reacted for 10 minutes. Next, the mixture was heated to 130 ° C., and 23 parts of N, N′-dimethylbenzylamine was added as an epoxy polymerization catalyst. This temperature was maintained until the epoxy equivalent weight reached 880. 90 parts of additive polyether (BYK Chemie, trade name “K-2000”) was added and maintained at 100 ° C. After 30 minutes, 211 parts of butyl alcohol and 1210 parts of isobutanol were added.

Immediately after this, diethylenetriamine and methyl isobutyl ketone were mixed and then heated and refluxed at 130 to 150 ° C. to remove the generated water, and 467 parts of ketimine obtained by cooling when the distillation of the generated water stopped at 150 ° C. And 450 parts of methylethanolamine were added to the reactor and the temperature was adjusted to 100 ° C. After another 30 minutes, the temperature was raised to 105 ° C. and 80 parts of N, N′-dimethylaminopropylamine was added. 75 minutes after the addition of the amine, 903 parts of a propylene glycol compound (manufactured by BASF, trade name “Plastitit 3060”) was added, diluted with 725 parts of propylene glycol phenyl ether, cooled, solid content 80%, amine concentration 1. 1 mol / kg of amine-modified epoxy resin A was obtained.

Production Example 4 Production of amine-modified epoxy resin B Epoxy resin based on bisphenol A having an epoxy equivalent of 188 in a reactor equipped with a stirrer, reflux condenser, internal thermometer and inert gas supply pipe 6150 parts of (bisphenol-A-diglycidyl ether) were heated to 125 ° C. under a nitrogen atmosphere together with 1400 parts of bisphenol A, 335 parts of dodecylphenol, 470 parts of p-cresol and 441 parts of xylene, and cooled for 10 minutes. Subsequently, the mixture was heated to 130 ° C. and 23 parts of N, N′-dimethylbenzylamine was added. This temperature was maintained until the epoxy equivalent weight reached 880. 90 parts of an additive polyether (manufactured by BYK Chemie, trade name “K-2000”) was added and maintained at 100 ° C. After 30 minutes, 211 parts of butyl alcohol and 1210 parts of isobutanol were added.

Immediately after this, diethylenetriamine and methyl isobutyl ketone were mixed and then heated and refluxed at 130 to 150 ° C. to remove the generated water, and 467 parts of ketimine obtained by cooling when the distillation of the generated water stopped at 150 ° C. And 350 parts of methylethanolamine were added to the reactor and the temperature was adjusted to 100 ° C. After another 30 minutes, the temperature was raised to 105 ° C. and 40 parts of N, N′-dimethylaminopropylamine was added. 75 minutes after the addition of the amine, 903 parts of a propylene glycol compound (trade name “Plastilit 3060” manufactured by BASF) was added, diluted with 695 parts of propylene glycol phenyl ether, cooled to 95 ° C., solid content 80%, amine An amine-modified epoxy resin B having a concentration of 0.9 mol / kg was obtained.

Production Example 5 Production of pigment paste Using the pigment-dispersed resin obtained in Production Example 1, each compounding component was sufficiently mixed at the ratio (mass%) shown in Table 1, and then the particle size was reduced by a ball mill. The pigment pastes P-1 to P-6 having a solid content of 65% were obtained by dispersing with a gauge so as to be 5 μm or less.

Explanation of numbers in parentheses in Table 1 1) Carbon black: MA100 (Mitsubishi Chemical Corporation)
2) DBTO: Dibutyltin oxide Neostan U-300 (Nitto Kasei Co., Ltd.)
3) Kaolin: ASP200 (manufactured by Engelhard)
3) Titanium dioxide: Taipure R900 (manufactured by DuPont)
4) Calcium ion exchanged amorphous silica fine particles: Shieldex 303 (manufactured by W. RG Race & Co, average particle size 3 μm, ion exchanged calcium ion content 6 mass%)
5) Silica fine particles: Silicia 446 (manufactured by Fuji Silysia)

Production Example 6 Production of Emulsion-1 A9949 parts of the amine-modified epoxy resin A obtained in Production Example 3 and 4872 parts of the curing agent obtained in Production Example 2 were mixed and stirred with 88% lactic acid. A mixed solution of 424 parts and 7061 parts of deionized water was added dropwise. Next, 12600 parts of deionized water was added dropwise over 30 minutes to obtain Emulsion-1 having a solid content of 32%.

Production Example 7 Production of Emulsion-2 The amine-modified epoxy resin A 10740 parts obtained in Production Example 3 and 4081 parts of the curing agent obtained in Production Example 2 were mixed and stirred with 88% lactic acid. A mixed solution of 424 parts and 7061 parts of deionized water was added dropwise. Next, 12600 parts of deionized water was added dropwise over 30 minutes to obtain an emulsion-2 having a solid content of 32%.

Production Example 8 Production of Emulsion-3 A mixture of 9949 parts of amine-modified epoxy resin B obtained in Production Example 4 and 4872 parts of the curing agent obtained in Production Example 2, and 424 parts of 88% lactic acid under stirring. And a mixture of 7061 parts of deionized water were added dropwise. Next, 12600 parts of deionized water was added dropwise over 30 minutes to obtain Emulsion-3 having a solid content of 32%.

Examples 1-8, Comparative Examples 1-2
The respective blending components were sufficiently mixed at the paint blending ratio (mass%) shown in Table 2 to obtain cationic electrodeposition paint compositions of Examples 1-8. The obtained electrodeposition paint had a solid content of 20%.

(Evaluation method of paint and coating film)
The cationic electrodeposition coating compositions obtained in the above Examples and Comparative Examples and the electrodeposition coating films obtained by electrodeposition coating were evaluated by the following methods. The evaluation results are shown in Table 3.

(1) Method for measuring the viscosity of the coating film Cationic batteries obtained by the above-mentioned Examples and Comparative Examples were applied to a cold-rolled steel sheet for automobiles that had been treated with zinc phosphate (PBL-3060, manufactured by Nihon Parkerizing Co., Ltd.). The coating material was electrodeposited under the conditions of a coating temperature of 30 ° C., a voltage of 200 V, and an electrodeposition time of 3 minutes so that the dry film thickness was 15 μm. After washing with water and air-drying at room temperature for 30 minutes to remove the moisture from the coating film, the wet coating film was scraped and collected as a sample. The sample thus obtained was measured with a viscoelasticity measuring apparatus MR300 (manufactured by UBM Co., Ltd.) in a steady flow viscosity measurement mode at a measurement temperature of 120 ° C., a viscosity at a shear rate of 5S- ¹ and a shear rate of 50S- ¹ Viscosity was measured.

(2) Evaluation method of edge cover properties To a cutter knife (OLFA, LB-50K) treated with zinc phosphate, the cationic electrodeposition paint obtained by the above examples and comparative examples was dried to a film thickness of 15 μm. The electrodeposition was performed under the conditions of a paint temperature of 30 ° C., a voltage of 200 V, and an electrodeposition time of 3 minutes. Electrodeposited. After washing with water, baking at 170 ° C. for 20 minutes, sharpening the cross section of the cutter knife covered with the electrodeposition coating film, measuring the film thickness at the tip with a digital microscope (VH-500, manufactured by Keyence Corporation) The film thickness at the tip was evaluated as follows.

◎: 4 μm or more ○: 2 μm or more, less than 4 μm
Δ: 1 μm or more and less than 2 μm ×: less than 1 μm

(3) Evaluation method of smoothness Cationic electrodeposition paints obtained by the above-mentioned examples and comparative examples were applied to a cold-rolled steel sheet for automobiles treated with zinc phosphate (manufactured by Parkerizing Japan, PBL-3060). The electrodeposition was performed under the conditions of a coating temperature of 30 ° C., a voltage of 200 V, and an electrodeposition time of 3 minutes so that the dry film thickness was 15 μm. Electrodeposited. After rinsing with water, baking was performed at 170 ° C. for 20 minutes. The roughness Ra (μm) was measured, and the average roughness (Ra) was evaluated as follows.

◎: Less than 0.25 μm ○: 0.25 μm or more, less than 0.30 μm ○ Δ: 0.30 μm or more, less than 0.35 μm Δ: 0.35 μm or more, less than 0.40 μm ×: 0.40 μm or more

Claims (3)

Cationic electrodeposition characterized by comprising (a) an amine-modified epoxy resin having an amine concentration of 1.0 mol / kg or more, (b) a blocked isocyanate compound, and (c) cation-exchanged amorphous silica fine particles as essential components. Paint composition. The cationic electrodeposition coating composition according to claim 1, wherein the content of the component (c) is 0.3 to 2.0 mass% with respect to the solid content of the total content of the components (a) and (b). . An electrodeposition coating method comprising electrodeposition coating the cationic electrodeposition coating composition according to claim 1 or 2.