JP2014177514A - Cationic electrodeposition coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cationic electrodeposition coating composition which hardly causes cissing on a coating film, can sufficiently ensure glossiness and smoothness and further can ensure the initial characteristics even if a coating material resides for a long period of time without impairing characteristics such as corrosion resistance, chemical resistance, ground adhesiveness and topcoating suitability which are required for a cationic electrodeposition coating material.SOLUTION: A cationic electrodeposition coating composition comprises, as essential components; (1) a cationic resin (base resin) in which an amino group is cationized with an acid in an amine-modified epoxy resin containing the amino group; (2) a blocked poly-isocyanate (curing agent); and (3) a polyether polyol represented by the following general formula: [B]-[A]-[C]. [A] represents a linking group having (CH(CH)CHO) as a repeating unit, and [B] and [C] represent a linking group having (CHCHO) as a repeating unit and in which one terminal of the final repeating unit is an OH group.

Description

In the present invention, by using a novel anti-repellent agent, problems due to repelling are unlikely to occur in the painting process and the subsequent baking process. Therefore, the present invention has excellent properties in coating smoothness and paint storage stability. The present invention relates to an epoxy resin-based cationic electrodeposition coating composition.

Electrodeposition coating is superior to air spray coating and electrostatic spray coating for parts having a bag structure, such as automobiles and electrical appliances. It has come to be widely put to practical use such as coat coating. However, the demand for electrodeposition coating has been advanced, and there is a demand for an electrodeposition coating with fewer defects in appearance of the coating film than in the prior art.

One of the defects in the paint film is a phenomenon called repellency. It is a pinhole due to volatilization of volatile components remaining in the paint film before baking, oil droplets originally present in the electrodeposition paint, or from the surroundings before baking. The cause is a crater by oil droplets scattered on the electrodeposition coating. In electrodeposition paints, the film-forming component is usually present in water in a particle state with a particle size of around 100 nm. However, if the electrodeposition paint stays in the bath bath for a long time, some of the constituent components are particles. This detachment component also causes repellency to be formed on the coating film, causing defects in the coating film.

In the prior art, for example, a method in which an extender pigment such as kaolin is added and increased to increase the pigment concentration in the paint to prevent repellency has been frequently used. However, although this method is effective in reducing repellency, there is a basic problem that the gloss of the coating film is inevitably lowered and sufficient coating film smoothness cannot be obtained.

There are also attempts to prevent repelling by using various additives in combination. That is, in patent document 1, it is a technique which uses silicone oil together as a repellency inhibitor. Silicone oil is a compound with a low SP value in the first place, and is generally based on the idea that it is distributed at a high concentration in the upper layer of an electrodeposition coating film with a high SP value to suppress repellency. When the overcoating is further applied on the electrodeposition coating film, there is a problem that the adhesion of the overcoating is extremely lowered.

In Patent Document 2 and Patent Document 3, an acrylic resin having a specific structure is proposed as a repellency inhibitor. As specified in Patent Document 3, these techniques basically specify the SP value of an acrylic resin, and, as in Patent Document 1, distribute acrylic resin at a high concentration in the upper layer portion of the coating film. Is to suppress. Depending on the amount of acrylic resin used, even if the repellency can be reduced, there may be a problem in the adhesion of the top coat. On the contrary, the acrylic resin becomes an oil droplet component, which may promote the repellency.

In Patent Document 4, a combination of a vinyl resin having a specific SP value and a polyalkylene glycol is proposed as a repellency inhibitor. In this case, however, the SP value of the vinyl resin and the polyalkylene glycol must be strictly specified. If both are not an appropriate combination, a sufficient repellency effect cannot be exhibited.

In patent document 5, the crosslinked resin particle is proposed as a repellency inhibitor. As shown in the production examples, specifically, crosslinked resin particles obtained by combining various monofunctional vinyl monomers with bifunctional vinyl monomers and emulsion-polymerizing them. When such crosslinked resin particles are used in an electrodeposition paint, the gloss is basically lowered according to the amount thereof. Therefore, the repelling effect of the present technology is considered to be because the repelling is difficult to be visually observed due to the decrease in gloss. In addition, the presence of the crosslinked resin particles naturally reduces the flowability of the coating film, so that a smooth coating film appearance is not achieved.

Japanese Patent Laid-Open No. 5-140489 JP-A-10-110124 Japanese Patent Laid-Open No. 2008-239989 JP 2001-89685 A JP 2002-356646 A

  Various required performances required for electrodeposition paints, such as corrosion resistance, water resistance, chemical resistance, substrate adhesion, coating workability, etc. When the top coat is applied after the electrodeposition coating, the smoothness of the top coat is sufficiently secured, and even when the paint stays in the bath for a long time, the initial characteristics are problematic. It is an object of the present invention to provide an electrodeposition coating having excellent storage stability that is ensured without any problems.

That is, the present invention has been made to solve the above-described problems. Specifically, (a) as a constituent component, (1) a cationic resin (group) in which the amino group of an amine-modified epoxy resin is cationized with an acid. Agent resin), (2) blocked polyisocyanate (curing agent), and (3) a cationic electrodeposition coating composition containing a polyether polyol represented by the following general formula as an essential component,
General Formula [B]-[A]-[C] Here, [A] represents a linking group having (CH (CH ₃ ) CH ₂ O) as a repeating unit.
[B], [C]: represents a linking group having (CH ₂ CH ₂ O) as a repeating unit and one terminal of the final repeating unit being an OH group.

(B) Further, an amine-modified epoxy resin (1) containing an amino group is obtained by reacting an amine with an epoxy resin obtained by reacting a polyphenol glycidyl ether, a polyol glycidyl ether, and a polyphenol. It is a cationic electrodeposition coating composition that is an epoxy resin,

(B) Furthermore, the molecular weight of [A] of the polyether polyol (3) is 500 to 2000, and the total of [B] and [C] parts is 5 to 90% by weight in the whole (3). A cationic electrodeposition coating composition,

(C) Further, the cationic electrodeposition coating composition in which the polyether polyol (3) is 0.5 to 10 parts by weight with respect to 100 parts by weight of the total solid content of the cationic resin (1) and the block polyisocyanate (2). A composition,

(D) Furthermore, the cationic electrodeposition coating composition in which the polyether polyol (3) is 1 to 6 parts by weight with respect to 100 parts by weight of the total solid content of the cationic resin (1) and the block polyisocyanate (2). And

(E) Furthermore, it is a cationic electrodeposition coating composition in which the molecular weight of [A] of the polyether polyol (3) is 700 to 1500, and the sum of the [B] and [C] parts of (3) is (3) It relates to a cationic electrodeposition coating composition that is 5 to 55% by weight in the whole.

  By applying the electrodeposition paint of the present invention, almost no repelling occurs in the appearance of the coating film without impairing various required performances such as corrosion resistance, chemical resistance, substrate adhesion, and coating workability. In addition, gloss, smoothness, appropriate top coating, etc. are sufficiently ensured. Even when the paint stays in the bath liquid tank for a long time, the initial characteristics can be secured without any problem.

The present invention will be specifically described below.
[(1) Cationic resin (base resin)]
The cationic resin (1) in the present invention is a cationic amine-modified epoxy resin obtained by cationizing an amine-modified epoxy resin obtained by reacting an epoxy resin with an amine with an acid.

The epoxy resin before the amine is reacted is preferably an epoxy resin having two or more epoxy groups per molecule on average, and its molecular weight is preferably 200 to 7000, particularly preferably 300 to 4000. Specifically, one example is glycidyl ether of polyphenol having two or more phenolic hydroxyl groups in one molecule, or a polycondensate thereof. Preferred polyphenols include resorcin, hydroquinone, 2,2-bis. -(4-hydroxyphenyl) -propane (commonly called bisphenol A), 4,4'-dihydroxybenzophenone, 1,1-bis- (4-hydroxyphenyl) -methane, 1,1-bis- (4-hydroxyphenyl) -Ethane, 4,4'-dihydroxybiphenyl, phenol or cresol novolak, and the like, but are not limited thereto, and a mixture of the above epoxy resins is also possible.

Other examples include glycidyl ethers of polyols having two or more alcoholic hydroxyl groups in one molecule, or polycondensates thereof. Preferred polyols include ethylene glycol, propylene glycol, 1,4-butanediol, , 6-hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol, 1,4-cyclohexanediol and other low molecular diols, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, bisphenol A and polyoxyethylene group or polyoxypropylene An oligomer polyol such as a compound having a group bonded thereto can be mentioned, but is not limited thereto, and 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 polyols, 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.

In addition, amino group-containing linking agents include primary amines such as ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, monoethanolamine, dimethylaminopropylamine, diethylaminopropylamine, or hexamethylenediamine. The diamine which secondaryized each amino group of diamines etc. can be mentioned. Moreover, chain length extension by polyisocyanate is also possible. 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.

A particularly preferred epoxy resin is an epoxy resin obtained by linking the above-mentioned polyphenol glycidyl ether and polyol glycidyl ether with polyphenol. Examples of polyphenols include resorcin, hydroquinone, 2,2-bis- (4-hydroxyphenyl) -propane (commonly called bisphenol A), 4,4′-dihydroxybenzophenone, 1,1-bis- (4-hydroxyphenyl) -methane. 1,1-bis- (4-hydroxyphenyl) -ethane, 4,4′-dihydroxybiphenyl, etc., or a mixture thereof, but is not limited thereto.

The high molecular weight reaction using the above linking agent can be carried out in a solvent-free melt, but it can also be carried out in a system to which a small amount of solvent is added. The solvent is not particularly limited as long as it does not participate in the reaction. The reaction temperature is suitably 40 to 180 ° C.

The amines that modify the epoxy resin include methylamine, ethylamine, n-propylamine, isopropylamine, monoethanolamine, n-propanolamine, isopropanolamine, diethylamine, diethanolamine, N-methylethanolamine, N-ethylethanolamine. , Ethylenediamine, diethylenetriamine, hydroxyethylaminoethylamine, ethylaminoethylamine, methylaminopropylamine, dimethylaminopropylamine, diethylaminopropylamine and the like, and mixtures thereof. Of these, alkanolamines having a hydroxyl group are particularly preferred. Alternatively, the primary amino group may be blocked by reacting with a ketone in advance and then reacted with the remaining active hydrogen and an epoxy group. As a specific method of amination, it can be carried out in a solvent or in a melt without solvent, and the reaction temperature is suitably 40 to 150 ° C.

The base number in the amine-modified epoxy resin used in the present invention is designed in the range of 10 to 200 mgKOH / g-solid, more preferably 30 to 150 mgKOH / solid. If the base number is less than 20 mgKOH / g-solid, sufficient water dispersibility and electrophoretic properties cannot be secured, and if it exceeds 200 mgKOH / g-solid, the coating film becomes brittle and the water resistance is lowered to obtain sufficient performance. It's hard to be done.

A specific method for cationizing the amine-modified epoxy resin of the present invention can be carried out by neutralizing an amino group with a protonic acid, and particularly preferable acids include formic acid, acetic acid, lactic acid, propionic acid, citric acid. Examples include acids, malic acid, sulfamic acid phosphoric acid, toluene sulfonic acid, naphthalene sulfonic acid, and the like, or mixtures thereof. The neutralization degree of the acid is preferably 15 to 85%.

[(2) Blocked polyisocyanate (curing agent)]
The blocked polyisocyanate (curing agent) (2) 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, Examples include 2,4- or 2,6-tolylene diisocyanate and mixtures thereof, p-phenylene diisocyanate, diphenylmethane-4,4′-diisocyanate, polymethylene polyphenyl diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate. 1,3 or 1,4-bis- (isocyanatomethyl) -cyclohexane, dicyclohexylmethane-4,4′-diisocyanate, bis- (isocyanatomethyl) -norbornane, 3 or 3 Examples include 4-isocyanatomethyl-1-methylcyclohexyl isocyanate, m- or p-xylylene diisocyanate, m- or p-tetramethylxylylene diisocyanate, and a burette modified product or isocyanurate modified product of the above isocyanate. However, the present invention is not limited to these, and a mixture of the above polyisocyanates is also possible.

Furthermore, it is also possible to connect a part of the isocyanate group of the polyisocyanate with a polyol. For example, low molecular diols such as ethylene glycol, propylene glycol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol, 1,4-cyclohexanediol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, poly Examples thereof include oligomeric diols such as lactone diols, polyisocyanates linked by polyols such as trimethylolethane, trimethylolpropane, and pentaerythritol, and mixtures thereof.

Examples of the blocking agent include aliphatic alcohol compounds such as methanol, ethanol, n-butanol and 2-ethylhexanol, cellosolve compounds such as ethylene glycol monobutyl ether and ethylene glycol monohexyl ether, diethylene glycol monoethyl ether and diethylene glycol monobutyl ether. Carbitol compounds, oxime compounds such as acetone oxime, methyl ethyl ketone oxime, cyclohexanone oxime, lactam compounds such as ε-caprolactam, phenol compounds such as phenol, cresol and xylenol, active methylene such as ethyl acetoacetate and diethyl malonate Examples thereof include a group-containing compound or a mixture thereof.

The reaction between the polyisocyanate and the blocking agent can be carried out in a solvent or in a melt. 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, cyclohexane, and isophorone, and aromatics such as benzene, toluene, xylene, chlorobenzene, and nitrobenzene. Examples thereof include hydrocarbons, cyclic ethers such as tetrahydrofuran, and halogenated hydrocarbons such as chloroform. Although there is no limitation in particular about reaction temperature, Preferably it is 30-150 degreeC.

[(3) Polyether polyol]
The polyether polyol (3) in the present invention is a compound having (CH (CH ₃ ) CH ₂ O) and (CH ₂ CH ₂ O) as repeating units in one molecule. It can be expressed by a formula. Generally, it is called a pluronic-type polyether polyol.
General Formula [B]-[A]-[C] Here, [A] represents a linking group having (CH (CH ₃ ) CH ₂ O) as a repeating unit.
[B], [C]: represents a linking group having (CH ₂ CH ₂ O) as a repeating unit and one terminal of the final repeating unit being an OH group.

About the molecular weight of [A] of polyether polyol (3), Preferably it is 500-2000, More preferably, it is 700-1500. The total of the [B] and [C] parts of the polyether polyol (3) is preferably 5 to 90% by weight, more preferably 5 to 55% by weight in the whole (3).

  A commercially available product can be used as the polyether polyol (3), for example, Sanyo Chemical Industries, New Pole PE-71, PE-75, PE-108, ADEKA, Adeka Pluronic. Examples thereof include, but are not limited to, L-34, L-61, F-68, P-85, L-121, BASF Corporation, Pluronic L31, L43, L64, and the like.

Regarding the quantitative ratio of the components (1), (2) and (3) in the present invention, the content ratio of the cationic resin (base resin) (1) and the blocked polyisocyanate (curing agent) (2) is solid. The weight ratio is 90 to 40/10 to 60, preferably 85 to 40/15 to 60, and more preferably 80 to 55/20 to 45. For the polyether polyol (3), the polyether polyol (3) is preferably 0.1 to 20 parts by weight with respect to 100 parts by weight in total of the cationic resin (1) and the block polyisocyanate (2). More preferably, it is 0.5-10 weight part, More preferably, it is 1-6 weight part.

In the cationic electrodeposition coating composition of the present invention, extender pigments, coloring pigments, rust preventive pigments and the like can be used in combination as pigments generally used in the field of electrodeposition coatings as necessary. For example, extender pigments such as kaolin (clay), talc, calcium carbonate, silica, diatomaceous earth, barium sulfate, titanium white, carbon black, other inorganic or organic color pigments, zinc phosphate, iron phosphate, aluminum phosphate, calcium phosphate Prevention of zinc phosphite, aluminum phosphite, zinc cyanide, zinc oxide, aluminum tripolyphosphate, zinc molybdate, aluminum molybdate, calcium molybdate, zinc phosphomolybdate, aluminum phosphomolybdate, bismuth hydroxide, etc. Although a rust pigment can be mentioned, it is not limited to these.

In addition, paint additives commonly used in the field of electrodeposition paints, such as antifoaming agents, viscosity modifiers, surfactants, antioxidants, ultraviolet absorbers, and various organic solvents or curing catalysts can do.

Examples of the organic solvent include hydrocarbons such as toluene, xylene and terpene, alcohols such as methyl alcohol, isopropyl alcohol, n-butyl alcohol, 2-ethylhexyl alcohol, ethylene glycol and propylene glycol, ethylene glycol monoethyl Ethers, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, propylene glycol monoethyl ether, 3-methyl-3-methoxybutanol, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, and other ethers, methyl isobutyl ketone, cyclohexanone, isophorone, acetylacetone Ketones such as ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl Ether acetates, esters such as butyl acetate, or mixtures thereof.

Examples of the curing catalyst include tin compounds such as dibutyltin laurate, dibutyltin oxide and dioctyltin, bismuth compounds such as bismuth lactate, and amine compounds such as N-methylmorpholine, and other resins such as acrylic resins, polyester resins, A urethane resin, a butadiene resin, or the like can be contained.

[Preparation of electrodeposition coating composition]
An amine-modified epoxy resin, a blocked polyisocyanate (curing agent), a polyether polyol, a water-dispersed resin liquid obtained by dispersing formic acid, acetic acid, lactic acid or the like as a neutralizing agent in an aqueous medium, and obtained from the above-described pigment. A method of obtaining an electrodeposition coating composition by mixing a pigment paste and, if necessary, an organic solvent and adjusting the concentration with water, is generally an amine-modified epoxy resin, blocked polyisocyanate (curing agent), polyether There is also a method in which all of polyol, pigment paste, and neutralizing agent are mixed in advance and then dispersed in an aqueous medium to obtain an electrodeposition coating composition. The solid content of the electrodeposition paint is adjusted to around 20% and used for painting. A preferable amount of the neutralizing agent is determined so that the coating pH is adjusted to about 5 to 8.

[Electrodeposition coating method]
The cationic electrodeposition coating composition of the present invention can be applied to a desired article by known cationic electrodeposition coating, usually dispersed in water. The object to be coated is preferably a conductor that has been subjected to surface treatment such as zinc phosphate treatment in advance, but there is no particular problem even if the treatment is not performed. For the paint, the solid concentration is preferably about 5 to 40% by weight, more preferably 15 to 25% by weight, the pH is adjusted to 5 to 8, the bath liquid temperature is 15 to 35 ° C., and the load voltage is 100 to 450V. Under certain conditions, the object can be applied as a cathode. After the coated object is washed with water, it can be baked at 100 to 200 ° C. for 10 to 30 minutes in a baking oven to obtain a cured coating film. Although there is no restriction | limiting in particular in the film thickness of the coating film obtained from the cationic electrodeposition coating composition of this invention, 5-60 micrometers in a cured coating film, Preferably 10-40 micrometers is suitable.

Below, this invention is demonstrated with a manufacture example, an Example, and a comparative example. The present 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 Example 1 Production of amine-modified epoxy resin (1-1)]
A reaction apparatus having a stirrer, a thermometer, and a cooling pipe is prepared. 661 parts of DER-331 (Dow Chemical Japan Co., Ltd. bisphenol A type liquid epoxy resin), 289 parts of bisphenol A, and 1 part of dimethylbenzylamine were charged into a reactor, and the temperature was raised to 150 ° C. by stirring and heating. After holding at 150 ° C. for 6 hours, 451 parts of methyl isobutyl ketone was gradually added and cooled to 80 ° C. Next, 105 parts of diethanolamine was added and the temperature was raised to 100 ° C. After holding at 100 ° C. for 2 hours, it was cooled to 80 ° C. and then taken out. The obtained amine-modified epoxy resin (1-1) had a solid content of 70%.

[Production Example 2 Production of amine-modified epoxy resin (1-2)]
A reaction apparatus having a stirrer, a thermometer, and a cooling pipe is prepared. 600 parts of glycier PP-300P (polypropylene glycol diglycidyl ether manufactured by Sanyo Chemical Industries), 1122 parts of DER-331 (bisphenol A liquid epoxy resin manufactured by Dow Chemical Japan Co., Ltd.), 684 parts of bisphenol A and dimethylbenzylamine 1 part was charged, and the temperature was raised to 150 ° C. by stirring and heating. After maintaining at 150 ° C. for 6 hours, 1121 parts of methyl isobutyl ketone was gradually added and cooled to 80 ° C. Next, 210 parts of diethanolamine was added and the temperature was raised to 100 ° C. After holding at 100 ° C. for 2 hours, it was cooled to 80 ° C. and then taken out. The resulting amine-modified epoxy resin (1-2) had a solid content of 70%.

[Production Example 3 Production of Blocked Polyisocyanate (2-1)]
A reaction apparatus having a stirrer, a thermometer, and a cooling pipe is prepared. 840 parts of Millionate MR-400 (Nippon Polyurethane Industry Co., Ltd. polymethylene polyphenyl isocyanate) and 235 parts of methyl isobutyl ketone were charged and heated to 100 ° C. with stirring and heating. Thereafter, a solution of 339 parts of ε-caprolactam previously dissolved in 110 parts of methyl isobutyl ketone was added dropwise over 1 hour while maintaining the reactor temperature at 100 ° C., and the reaction was carried out at 100 ° C. for 2 hours. Next, 500 parts of ethylene glycol monobutyl ether was added dropwise over 1 hour while maintaining 100 ° C. After holding at 100 ° C. for 2 hours, it was cooled to 80 ° C. and taken out. The obtained blocked polyisocyanate (2-1) had a solid content of 75%.

[Production Example 4 Production of pigment-dispersed resin]
A reaction apparatus having a stirrer, a thermometer, and a cooling pipe is prepared. 292 parts of methyl isobutyl ketone and 835 parts of Sumidur T-80 (tolylene diisocyanate manufactured by Sumika Bayer Urethane Co., Ltd.) were charged, and 686 parts of 2-ethylhexanol was added dropwise over 1 hour at 50 ° C. or less, and then 3 hours. The reaction intermediate was obtained by incubation.
Prepare another reactor with stirrer, thermometer, and condenser. Epototo YD-014 (Bisphenol A type solid epoxy resin manufactured by Nippon Steel Chemical Co., Ltd.) 3039 parts and methyl isobutyl ketone 1303 parts were charged, the temperature was raised to 95 ° C., and the reaction intermediate was charged. After maintaining at 95 ° C. for 5 hours, 1040 parts of ethylene glycol monobutyl ether was added, and methyl isobutyl ketone was distilled off at around 90 ° C. under reduced pressure. Thereafter, 1565 parts of ethylene glycol monobutyl ether was added, and a mixture of 409 parts of dimethylethanolamine and 579 parts of 50% lactic acid was added and maintained at 80 ° C for 3 hours. The obtained pigment-dispersed resin had a solid content of 60%.

[Preparation of aqueous dispersion resin solution]
Production Examples 5 to 16 (Production of aqueous dispersion resin liquids 1 to 12)
According to the formulation shown in Table 1, deionized water (10) was gradually added to the mixed resin neutralized product of (1) to (9) with good stirring to obtain respective aqueous dispersion resin liquids. Table 1 also shows the weight percent of the polyether polyol (3) based on 100 parts by weight of the total of the cationic resin (1) and the blocked polyisocyanate (2).

[Description of raw materials]
Pluronic L31
BASF polyether polyol (3)
Molecular weight of [A]: 950
Total of [B] and [C] parts in (3): 10% by weight
Adeka Pluronic L-34
ADEKA polyether polyol (3)
Molecular weight of [A]: 1200
Total of [B] and [C] parts in (3): 30% by weight
New Pole PE-108
Polyether polyol (3) manufactured by Sanyo Chemical Industries
Molecular weight of [A]: 3250
Total of [B] and [C] parts in (3): 80% by weight
Adeka Pluronic L-121
ADEKA polyether polyol (3)
Molecular weight of [A]: 3850
Total of [B] and [C] parts in (3): 10% by weight

[Preparation of pigment paste]
Production Examples 17 and 18 (Production of Pigment Pastes 1 and 2)
After mixing (1) to (5) with a dissolver according to the formulation shown in Table 2, each particle paste is dispersed using a horizontal sand mill until the particle gauge particle size is determined to be 10 μm or less as determined by a distribution diagram method. It was.

[Description of raw materials]
MA-100 Carbon Black Taipure R-900 manufactured by Mitsubishi Chemical Corporation Titanium oxide manufactured by DuPont KC-100 manufactured by Kyodo Pharmaceutical Co., Ltd. Dibutyltin oxide

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

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

The evaluation methods of paint and coating film performance are as follows.
(1) Repelling resistance (initial paint evaluation)
The coating film appearance of a 70 × 150 mm size coating test plate is observed to observe the presence or absence of repellency and craters.
◎: Number of repels or craters 0 to 1 ○: Number of repels or craters 2 to 3 ×: Number of repels or craters 4 or more (2) Gloss of coating film 60 degree specular reflectance with a gloss meter taking measurement.
(3) Ra
Ra is measured with a surface roughness meter.
Measurement conditions Cut-off: 2.5mm
Feeding speed: 0.5 mm / second (4) Salt spray resistance test Performed according to JIS-Z-2371. A scratch reaching the substrate is put on the electrodeposited surface with a cutter knife, and the rust width after 900 hours is evaluated.
○: Corrosion width of 3.0 mm or less from scratches on cutter knife ×: Corrosion width exceeds 3.0 mm from scratches on cutter knife (5) Acid resistance 20 ° C. After 120 hours immersion in 5% sulfuric acid aqueous solution Observe the surface condition.
○: There is almost no difference in gloss and appearance compared to the state before immersion. ×: There is a difference in gloss and appearance. (6) Alkali resistance After immersing in 1% sodium hydroxide aqueous solution at 20 ° C for 120 hours, the coated surface state is observed. .
○: There is almost no difference in gloss and appearance compared to the state before immersion. ×: There is a difference in gloss and appearance. (7) Cross-cut adhesion Adhesion of 100 squares with a width of 1 mm with a cutter knife on the coated plate. After sticking the cellophane tape on top, observe the adhesion when the cellophane tape is quickly peeled off.
○: No peeling ×: Peeling (8) Applicability for top coating After applying the top coating to the electrodeposition coated plate, a cross-cut adhesion test with a width of 2 mm is performed.
Top coating conditions Paint: Super Glymine # 1000 Baking conditions manufactured by Shinto Paint Co., Ltd .: 140 ° C. × 20 minutes Film thickness: 30 μm
○: No peeling with respect to the top coating ×: Peeling with respect to the top coating (9) While maintaining a state where the storage-stable paint was sealed so that moisture and the like would not fly off, the stirring was continued at 30 ° C. for one month, and then (1 The electrodeposition coating similar to the test of) is performed, and the presence or absence of an increase in the appearance of the coating film is observed.
○: Number of repellants or craters does not increase ×: Number of repellants or craters increases

According to the present invention, there is almost no repellency in the appearance of the coating film, gloss and smoothness are sufficiently achieved, and there are no problems with the properties of conventional paints in terms of corrosion resistance, chemical resistance, substrate adhesion, suitability for top coating, etc. A cationic electrodeposition coating composition that is ensured can be obtained.

Claims (7)

(1) In an amine-modified epoxy resin containing an amino group as a component, a cationic resin (base resin) having a base number of 10 to 200 mg KOH / g-solid and an amino group cationized with an acid, ( 2) A cationic electrodeposition coating composition comprising, as essential components, a blocked polyisocyanate (curing agent) and (3) a polyether polyol represented by the following general formula.
General Formula [B]-[A]-[C] Here, [A] represents a linking group having (CH (CH ₃ ) CH ₂ O) as a repeating unit.
[B], [C]: represents a linking group having (CH ₂ CH ₂ O) as a repeating unit and one terminal of the final repeating unit being an OH group. (1) The amine-modified epoxy resin containing an amino group is an amine-modified epoxy resin obtained by reacting an amine with an epoxy resin obtained by reacting a polyphenol glycidyl ether, a polyol glycidyl ether, and a polyphenol. The cationic electrodeposition coating composition according to claim 1.   The molecular weight of [A] of the polyether polyol (3) is 500 to 2000, and the sum of the [B] and [C] parts is 5 to 90% by weight in the total of (3). Alternatively, the cationic electrodeposition coating composition according to claim 2.   The polyether polyol (3) is 0.1 to 20 parts by weight with respect to 100 parts by weight of the total solid content of the cationic resin (1) and the blocked polyisocyanate (2). Alternatively, the cationic electrodeposition coating composition according to claim 3.   The polyether polyol (3) is 0.5 to 10 parts by weight with respect to 100 parts by weight of the total solid content of the cationic resin (1) and the blocked polyisocyanate (2). The cationic electrodeposition coating composition according to claim 3 or 4.   The polyether polyol (3) is 1 to 6 parts by weight with respect to 100 parts by weight of the total solid content of the cationic resin (1) and the blocked polyisocyanate (2). The cationic electrodeposition coating composition according to claim 3, claim 4 or claim 5. The molecular weight of [A] of the polyether polyol (3) is 700 to 1500, and the sum of the [B] and [C] parts of (3) is 5 to 55% by weight in the whole (3). The cationic electrodeposition coating composition according to claim 1, claim 2, claim 3, claim 4, claim 5, or claim 6.