JPH0841390A - Cationic electrodeposition coating composition containing reactive leveling agent - Google Patents

Abstract

PURPOSE:To obtain a cationic electrodeposition coating compsn. which is not lowered in adhesion to a top coating film and can prevent self-cissing and oil cissing, by blending a specific polymer as a leveling agent. CONSTITUTION:A cationic electrodeposition coating compsn. comprising (A) a hydrophilic film-forming resin having cationic groups and (B) a cross-linking agent, both dispersed in an aq. medium contg. a neutralizer, is blended with (C) 1-35wt.%, (in terms of solid content based on the solid resin content of the whole compsn.) polymer contg. 10-90wt.% polyoxyalkylene chain having a number-average mol.wt. of 400 to 4,000 in the molecule thereof and having a plurality of blocked isocyanate groups blocked with a blocking agent selected from among lactams, phenols, glycol ethers and oximes. An amine-modified epoxy resin is pref. used as the component (A). A blocked polyisocyanate compd. is used as the component (B).

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION The present invention relates to a cationic electrodeposition coating composition containing a reactive surface smoothing agent. When the electrodeposition coating film is baked and cured, pinholes or craters may occur due to volatilization of volatile components in the coating film. This is called self-rebellion. In addition, there is a so-called "oil cissing" phenomenon in which a large number of craters are generated in the electrodeposition coating film when an electrodeposition coating material containing oil droplets is applied or when oil droplets scattered from the surroundings adhere to the electrodeposition coating film before baking and curing. Can be seen.

Until now, various measures have been taken in order to prevent these cissing phenomena and keep the coating film surface smooth. For example, a method of suppressing the flowability of the coating film at the time of baking by increasing the pigment concentration in the coating film by adding kaolin, adding a high-viscosity resin having a large molecular weight, and the like. However, these measures are not sufficiently effective, and have drawbacks such as macroscopic smoothness of the coating film and poor adhesion to the top coating film.

Further, it has been proposed to add various additives to the cationic electrodeposition coating composition as a surface smoothing agent or an anti-repellent agent. Examples of such additives include polyoxyalkylene polyamines in JP-A-2-503573, reaction products of polyoxyalkylene polyamines and polyepoxides in JP-A-59-11760, and JP-A-64- Japanese Patent Publication No. 69678 discloses polyoxyalkylene glycol, Japanese Patent Publication No. 1-503239 discloses an addition product of a polyether urethane prepolymer and a secondary amine, and Japanese Patent Publication No. 4-26627 discloses isocyanurate-type hexamethylene diisocyanate. A low Tg crosslinking agent in which the monomer is blocked with ethylene glycol monoalkyl ether is proposed, respectively. However, although these additives are effective in preventing self-repellency, they are not effective in oil repellency, or have the drawback that the adhesion to the top coating film is reduced.

Therefore, the present invention is effective in preventing both self-repelling and oil-repelling, and further contains a reactive surface smoothing agent or anti-repelling agent which does not reduce the adhesion to the top coating film. A composition is provided.

DISCLOSURE OF THE INVENTION The present invention is a cationic electrodeposition coating composition prepared by dispersing (a) a hydrophilic film-forming resin having a cationic group and (b) a crosslinking agent in an aqueous medium containing a neutralizing agent. In the thing,
(C) A plurality of blocks containing 10 to 90% by weight of a polyoxyalkylene chain having a number average molecular weight of 400 to 4000 in the molecule and blocked with a blocking agent selected from lactams, phenols, glycol ethers or oximes. Provided is a cationic electrodeposition coating composition, which comprises a polymer having an isocyanate group as a solid content in an amount of 1 to 35% by weight of a resin solid content of the entire composition.

When the electrodeposition coating film is heated and cured, the component (c) is blocked by a blocking agent whose concentration on the surface of the coating film becomes high due to its surface chemical properties and which is dissociated at a relatively low temperature. Therefore, the surface portion of the coating film starts earlier than other portions. Even if oil droplets are attached due to the surface portion hardening quickly in this way, craters (oil cissing)
Does not occur.

Preferred Embodiment (a) A large number of hydrophilic film-forming resins that can be used in the cationic electrodeposition coating composition are known. These are amine-modified epoxy resins, amine-modified polyurethane polyol resins, amine-modified acrylic resins, amine-modified polybutadiene resins, and modified epoxy resins having sulfonium groups as cationic groups. However, since the surface smoothing agent or anti-crater agent of the present invention reacts like a blocked polyisocyanate crosslinking agent, a resin having this reaction as a curing mechanism, preferably an amine-modified epoxy resin is used.

These resins are typically bisphenol-type epoxy resins to primary amines, secondary amines, or tertiary amines.
It is obtained by addition reaction of a primary amine and an acid to open an epoxy ring. Further, as disclosed in JP-A-5-306327 of the present applicant, an oxazolidone ring is formed in the chain obtained by reacting a bisurethane compound obtained by reacting a diisocyanate with a lower alkanol and a bisphenol type epoxy resin. A resin obtained by adding an amine to an epoxy resin having the same as a starting material may be used.

A blocked polyisocyanate compound is used as the crosslinking agent (b) . The blocked isocyanate crosslinking agent can be obtained by an addition reaction of a polyfunctional isocyanate compound and an isocyanate blocking agent. Aliphatic, cycloaliphatic or aromatic polyisocyanates are used as polyfunctional isocyanate compounds. For example, tolylene diisocyanate, xylylene diisocyanate,
4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, their biurets, isocyanurates, and low molecular weight polyols such as adducts with trimethylolpropane are mentioned. On the other hand, the isocyanate blocking agent is one in which the blocked isocyanate compound formed by addition is stable at room temperature and can dissociate the blocking agent to regenerate a free isocyanate group when heated to 100 to 200 ° C. For example, lactam compounds (ε-caprolactam, γ-butyrolactam, etc.),
Phenolic compounds (phenol, cresol, xylenol, etc.), glycol ethers (ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol mono-2-ethylhexyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, diethylene glycol mono-2-) Ethylhexyl ether, propylene glycol monobutyl ether, propylene glycol monohexyl ether, propylene glycol mono-2-ethylhexyl ether, dipropylene glycol monobutyl ether, dipropylene glycol monohexyl ether, dipropylene glycol mono-2-ethylhexyl ether, etc.), oxime-based Compound (methyl ethyl Ton'okishimu, such as cyclohexanone oxime), and the like.

Component (c) The feature of the cationic electrodeposition coating composition of the present invention lies in the component (c).
Although there are several methods for synthesizing a polymer having a polyoxyalkylene chain and a plurality of blocked isocyanate groups in the molecule, preferred methods will be described.

The first method is to react a polyoxyalkylene polyol, polyoxyalkylene polyamine, or polyoxyalkylene polythiol with a partially blocked polyisocyanate compound to form active hydrogen-containing groups of the polyoxyalkylene compound and residual free isocyanate. It is a method of synthesis utilizing an addition reaction with a group.

As the polyoxyalkylene chain, a polyoxypropylene chain is preferable, and a bifunctional polyol, polyamine or polythiol is preferable.

The partially blocked polyisocyanate compound can be synthesized by reacting the above-mentioned polyisocyanate compound with the above-mentioned blocking agent in a proportion such that at least one free isocyanate group remains. As the polyisocyanate compound,
Polyisocyanate compounds having a functional number greater than 2, such as isocyanurate type, low molecular weight polyols such as adducts with trimethylolpropane, and polymethylene polyphenylene polyisocyanate (Polymeric MDI) are preferred.

By the reaction of the partially blocked polyisocyanate compound and the polyoxyalkylene active hydrogen compound, the blocked isocyanate-containing group is bonded to the polyoxyalkylene chain by a urethane bond, a thiourethane bond, or a urea bond.

In the second method, the epoxy ring of polyoxyalkylene polyol polyglycidyl ether is opened with a carboxyl group, a hydroxyl group or a thiol group, and the partially blocked polyisocyanate compound remains on the secondary alcoholic hydroxyl group produced. This is a method of adding a free cyanate group. Polyoxypropylene glycol diglycidyl ether is preferred.

Compounds that can be used for opening the epoxy ring include benzoic acid, linseed oil fatty acid, 2-ethylhexanoic acid, versatic acid, lactic acid, 12-hydroxystearic acid and other monocarboxylic acids; adipic acid, Dicarboxylic acids such as sebacic acid, isophthalic acid and dimer acid; mono- such as phenol, butylphenol, nonylphenol, bisphenol A and bisphenol F
Or polyphenol; thiols such as butyl mercaptan, 2-ethylhexyl mercaptan, and dodecyl mercaptan.

As is well known, a secondary alcoholic hydroxyl group is formed at the β-position of a propylene chain by opening the epoxy ring. Therefore, the addition reaction between this hydroxyl group and the residual free isocyanate group of the partially blocked polyisocyanate compound is utilized. Thus, a polymer having a polyoxyalkylene chain and a plurality of blocked isocyanate groups in the molecule can be synthesized.

The third method uses a monofunctional isocyanate group-containing acrylic monomer in which the isocyanate groups have been blocked in advance. Such monomers are obtained by reacting (meth) acryloyl isocyanate or 2-isocyanatoethyl (meth) acrylate with a blocking agent. A preferred monomer is N-methacryloylcarbamic acid 2-hexoxyethyl ester obtained by blocking methacryloyl isocyanate with ethylene glycol monohexyl ether.

The blocked isocyanate group-containing acrylic monomer is then copolymerized with an acrylic monomer containing a polyoxyalkylene chain and optionally other monomers. Acrylic monomer containing polyoxyalkylene chain,
It can be produced by reacting a polyoxyalkylene glycol having a terminal blocked with an ether or ester bond with a monoalcohol, phenol or monocarboxylic acid, and (meth) acrylic acid chloride. The end-capped polyoxypropylene methacrylate monomer is commercially available under the name of Bremmer P or the like. Any other copolymerizable monomers include alkyl (meth) acrylates (methyl, ethyl, n-propyl, n-butyl, 2-
Conventional ethylenically unsaturated monomers such as ethylhexyl, 2-hydroxyethyl, etc.), styrene, vinyl acetate, etc.

The polymers produced by the first to third methods contain 10 to 90% by weight of polyoxyalkylene chain,
It should preferably contain 30 to 80% by weight. Moreover, the number average molecular weight of those polyoxyethylene chains is 400-
It should be 4,000, preferably 500-1,000.

Coating Composition The cationic electrodeposition composition of the present invention can be coated in the same manner as a conventional cationic electrodeposition coating composition except that it contains the component (c). The proportion of component (c) in the coating composition is 0.1 to 35% by weight, preferably 0.5 to 20% by weight, of the resin solid content of the entire composition as a solid content. By adding the component (c), self-repellency and oil repellency can be prevented and the surface smoothness of the coating film can be improved without lowering the adhesion to the topcoat coating film. Further, as a secondary effect, the defoaming property of the paint is improved.

Neutralization of the cationic electrodeposition coating composition of the present invention
The solubilization is carried out by mixing the components (a), (b) and (c),
It is carried out by dispersing in a water-based medium containing a water-soluble organic acid such as formic acid, acetic acid, propionic acid, lactic acid, citric acid, malic acid, tartaric acid, acrylic acid or an inorganic acid such as hydrochloric acid or phosphoric acid as a neutralizing agent. .

The cationic electrodeposition coating composition of the present invention may further contain a conventional coating additive, such as titanium dioxide, carbon black, color pigments such as red iron oxide, talc, calcium carbonate, clay and silica, if necessary. The extender pigment may be dispersed with a pigment dispersion resin and added as a pigment dispersion paste. If necessary, rust preventive pigments such as chromium pigments (strontium chromate, zinc chromate), lead pigments (basic lead silicate, basic lead chromate, lead tin, cyanamide lead, etc.), phosphoric acid pigments ( Paint additives such as aluminum phosphate, zinc phosphate, calcium phosphate, etc., boric acid-based pigments (barium metaborate, etc.), organic solvents, curing catalysts (dibutyltin oxide, etc.) can be added.

The cathode electrodeposition coating composition of the present invention can be applied to a desired substrate surface by cationic electrodeposition coating. Cationic electrodeposition coating is carried out according to a method known per se, generally by diluting with deionized water so that the solid content concentration becomes 5 to 40% by weight, preferably 15 to 25% by weight, and further adjusting the pH to 5 An electrodeposition bath composed of the cathodic electrodeposition coating composition of the present invention adjusted within the range of 0.5 to 8.5 is usually adjusted to a bath temperature of 20 ° C to 35 ° C and a load voltage of 100 to 450V.
It can be performed under the conditions of. The baking temperature of the coating film is generally 1
10 to 200 ° C, preferably 150 to 180 ° C
It's 30 minutes.

In the following production examples and examples, all "parts" and "%" are based on weight.

Synthesis of Component (a) Production Example 1 A flask equipped with a stirrer, a cooler, a nitrogen injection tube, a thermometer and a dropping funnel was prepared. Into this flask, bisphenol A epoxy resin and 2,4- / 2,6-
Epoxy equivalent 475 synthesized from tolylene diisocyanate (weight ratio 8/2), oxazolidone ring-containing epoxy resin 285.0 g, and bisphenol A epoxy resin 38, epoxy equivalent 950
0.0 g, p-nonylphenol 77.0 g, and methyl isobutyl ketone 196.7 g were charged and the temperature was raised to homogenize. To this, 3.0 g of benzyldimethylamine was added and reacted at 130 ° C. until the epoxy equivalent became 1140. It is then cooled and diethanolamine 19.2.
g, N-methylethanolamine 27.0 g, and aminoethyl ethanolamine ketiminate (79% methylisobutyltoken solution) 30.6 g were added, and 110
The reaction was performed at 0 ° C for 2 hours. Then, it is diluted with methyl isobutyl ketone to a non-volatile content of 80% to obtain a base resin a-1.
I got

Production Example 2 A flask equipped with a stirrer, a condenser, a nitrogen injection tube, a thermometer and a dropping funnel was prepared. In this flask,
92 g of 2,4- / 2,6-tolylene diisocyanate (weight ratio = 8/2), 95 g of methyl isobutyl ketone and 0.5 g of dibutyltin dilaurate were added, and 21 g of methanol was further added dropwise while stirring this. The reaction started at room temperature and was heated to 60 ° C. due to heat generation. Then, after continuing the reaction for 30 minutes, 57 g of ethylene glycol mono-2-ethylhexyl ether was dropped from a dropping funnel, and 42 g of a 5 mol adduct of bisphenol A-propylene oxide was further added. The reaction is mainly 60 ℃
It carried out in the range of -65 degreeC, and it continued until the isocyanate group disappeared, measuring IR spectrum. Next, 365 g of an epoxy resin having an epoxy equivalent of 188, which was synthesized from bisphenol A and epichlorohydrin, was added, and the temperature was changed to 125 ° C.
The temperature was raised to. Then benzyldimethylamine 1.0
g was added and the mixture was reacted at 130 ° C. until the epoxy equivalent was 410. Subsequently, when 87 g of bisphenol A was added to the reaction vessel and reacted at 120 ° C., the epoxy equivalent was 1
It became 190. Then cool down and diethanolamine 1
1 g, 24 g of N-methylethanolamine, and 25 g of a ketimine compound of aminoethylethanolamine (79% by weight methyl isobutyl ketone solution) were added, and 110
The reaction was performed at 0 ° C for 2 hours. Then, it was diluted with methyl isobutyl ketone to a nonvolatile content of 80% to obtain an oxazolidone ring-containing base resin a-2.

Synthesis of Component (b) Production Example 3 A flask equipped with a stirrer, a cooler, a nitrogen injection tube, a thermometer and a dropping funnel was prepared. In this flask, as a polyisocyanate compound, hexamethylene diisocyanate trimer (trade name "Coronate HX": manufactured by Nippon Polyurethane Co., Ltd.) 199 g, methyl isobutyl ketone 32 g, and dibutyl tin dilaurate 0.0.
And 5 g were added. To this, 87.0 g of methyl ketoxime was added dropwise from a dropping funnel over 1 hour while stirring while blowing nitrogen. The reaction was carried out until the absorption spectrum of the NCO group disappeared in the IR spectrum to obtain a curing agent b.

Production of Pigment Paste Production Example 4 Bisphenol type epoxy resin having an epoxy equivalent of 450 was reacted with 2-ethylhexanol half-blocked isophorone diisocyanate to give 1- (2-hydroxyethylthio) -2-propanol and dimethylolpropionic acid. 125.0 g of a resin varnish for dispersing pigments which has been tertiary-sulfonated with (30.6% of tertiary-sulfonation, 60% of resin solid content), 400.0 g of ion-exchanged water, 8.5 g of carbon black, 72.0 g of kaolin, Titanium dioxide 345.0g and aluminum phosphomolybdate 75.0g
Was dispersed with a sand grind mill and further pulverized to a particle size of 10 μm or less to obtain a pigment dispersion paste.

Synthesis of Partially Blocked Polyisocyanate Production Example 5 Polymeric MDI (Polymethylene polyphenylene polyisocyanate, Nippon Polyurethane Co., Ltd. Coronate 1104) 360. was placed in a container equipped with a stirrer, a cooler, a nitrogen injection tube, a thermometer and a dropping funnel. 5 g was added, the mixture was diluted with 217.6 g of methyl isobutyl ketone, 0.3 g of dibutyl tin laurate was added, and after heating to 50 ° C., 147.9 g of methyl ethyl ketoxime was added dropwise under stirring in a nitrogen atmosphere for 2 hours. Cool and raise reaction temperature to 50
The reaction was carried out by keeping the temperature at ℃. 70% solid content

Production Example 6 Polymeric MDI 1 was added to the reaction vessel used in Production Example 5.
Add 20.2g, 70.2g of methyl isobutyl ketone
Dilute with dibutyltin dilaurate 0.2g,
After the temperature was raised to 50 ° C., 43.8 parts of n-hexyl cellosolve was added dropwise under stirring in a nitrogen atmosphere over 1 hour, and while cooling, the reaction temperature was kept at 50 ° C. for reaction. Solid content 70
%

Production Example 7 The reaction vessel used in Production Example 5 was charged with isocyanurate type tolylene diisocyanate trimer (Coronate 2030, solid content 60.0%, manufactured by Nippon Polyurethane Co.) 1465.
0 g was added, 0.3 g of dibutyltin dilaurate was added, the temperature was raised to 50 ° C., and n-hexyl cellosolve 292.
0 g of the solution was added dropwise under stirring in the atmosphere for 1 hour, cooled during this time, and the reaction temperature was kept at 50 ° C. for reaction. Solid content 6
6.6%

Synthesis Example 8 of Component (c) Production Example 8 891.0 g of polypropylene glycol diglycidyl ether having an epoxy equivalent of 297 was placed in a container equipped with a stirrer, a cooler, a nitrogen injection tube, a thermometer and a dropping funnel.
Versadim 216 (synthetic fatty acid) 576.0 g and 1
30-0.5 g of 2-hydroxystearic acid was charged and heated to 100 ° C under a nitrogen atmosphere. To this, 2.7 g of dimethylbenzylamine was added, and the temperature was raised to 140 ° C., maintained at this temperature until the acid value was 5 or less, cooled after confirming that the acid value reached 5 or less, and cooled to 110 ° C. with methyl. 754.3 g of isobutyl ketone was added for dilution. Continue cooling 5
After reaching 0 ° C., 726.3 g of the partially blocked polyisocyanate of Production Example 5 was added dropwise over 1 hour, and the reaction temperature was kept at 50 ° C. by cooling during this period. Infrared absorption spectrum until absorption of isocyanate groups virtually disappears 6
It was kept at 0 ° C. for 1 hour to produce a surface smoothing agent c-1.
Solid content 70%, PO content 39%

Production Example 9 The container used in Production Example 8 was charged with 408.0 g of polypropylene glycol having a molecular weight of 1000 and 174.9 g of methyl isobutyl ketone, heated to 60 ° C., and then produced in Production Example 6
234.3 g of the partially blocked polyisocyanate of was added dropwise with stirring in a nitrogen atmosphere for 1 hour, and while cooling, the reaction temperature was maintained at 60 ° C. The surface smoothing agent c-2 was produced by holding at 60 ° C. for 1 hour until the absorption of the isocyanate group disappeared by infrared absorption spectrum. Solid content 7
0%, PO content 73%

Production Example 10 Polypropylene glycol diglycidyl ether 594.0 having an epoxy equivalent of 297 was added to the container used in Production Example 8.
g, Versadime 216 288.0 g, and 12-hydroxystearic acid 300.5 g were charged and heated to 100 ° C. under a nitrogen atmosphere. 2.7 g of dimethylbenzylamine was added thereto, and the temperature was raised to 140 ° C., and then maintained at this temperature until the acid value became 5 or less. After confirming that the acid value has reached 5 or less, it is cooled, and methyl isobutyl ketone 5
03.9g was added and diluted. Continue to cool at 50 ℃
1452.6 g of the partially blocked polyisocyanate of Production Example 5 was added dropwise over 1 hour, and the reaction temperature was maintained at 60 ° C. by cooling during this period. It was kept for 1 hour until the absorption of the isocyanate group disappeared by infrared absorption spectrum, to produce a surface smoothing agent c-3. Solid content 70
%, PO content 27%

Production Example 11 The container used in Production Example 8 was charged with polypropylene glycol diglycidyl ether 1420.
0 g and bisphenol A (114.0 g) were charged, heated to 100 ° C. under a nitrogen atmosphere, added with dimethylbenzylamine (3.6 g), heated to 170 ° C., and reacted at this temperature until the epoxy equivalent became 1530. Immediately after that, cool at 140 ° C. with 12-hydroxystearic acid 30
0.5 g was added and reacted until the acid value became 5 or less.
After confirming that the acid value reached 5 or less, the mixture was cooled and then diluted at 110 ° C. by adding 698.3 g of methyl isobutyl ketone. When cooling was further continued and the temperature reached 50 ° C., 1757.2 g of the partially blocked isocyanate of Preparation Example 7 was added dropwise over 2 hours, while cooling was performed to maintain the reaction temperature at 60 ° C.
The surface smoothing agent c-4 was produced by holding at 60 ° C. for 1 hour until the absorption of the isocyanate group disappeared by infrared absorption spectrum. Solid content 70%, PO content 47%

Production Example 12 60 g of butyl cellosolve was placed in a five-necked flask equipped with a reflux condenser, a stirrer, and a dropping funnel, and 130 ° C.
It was kept heated. Into this, Bremmer P (end-capped polypropylene glycol monomethacrylate) 64.1
g, 8.6 g of isobutyl acrylate, 15 parts of an adduct of methacryloyl isocyanate and n-hexyl cellosolve, and 2-hydroxyethyl methacrylate 1
A mixture of 2.3 g and azobisisobutyronitrile 3.2 g was added dropwise from a dropping funnel over 3 hours. After the dropping was completed, the mixture was kept at 130 ° C for about 30 minutes, and then a mixture of 8 g of butyl cellosolve and 0.5 g of azobisisobutyronitrile was added dropwise from the dropping funnel over about 20 minutes, and then kept at 130 ° C for about 1 hour. Then, a surface smoothing agent c-5 was produced. Solid content 58%

Production Example 13 (for Comparative Example) The polypropylene glycol diglycidyl ether ring-opening adduct of Production Example 8 before the reaction with the partially blocked polyisocyanate was used as the surface smoothing agent c-6. Solid content 70
%

Production Example 14 (for Comparative Example) Commercially available polyoxypropylene diamine Jeffamine D-2000 (Molecular weight 200 manufactured by Texaco Chemical Co., Ltd.)
0) was used as the surface smoothing agent c-7.

Production Example 15 (for Comparative Example) The container used in Production Example 8 was charged with 243.1 g of hexamethylene diisocyanate and 364.
6 g was charged and heated to 50 ° C. under a nitrogen atmosphere. To this, 0.5 g of dibutyltin dilaurate was added to give a molecular weight of 11
1162.6 g of polyoxyalkylene glycol (ethylene oxide-propylene oxide copolymer) of 00 was added dropwise, the reaction temperature was kept at 70 ° C or lower during this period, and the reaction was carried out at the same temperature until the NCO equivalent reached the theoretical value. Then, 349.7 g of a methylisobutylketone solution of ketimine of diethylenetriamine and methylisobutylketone (amine equivalent 130) was added, the temperature was raised to 90 ° C., and the same temperature was maintained until all isocyanate groups disappeared, and the surface was smoothed. Agent c-8 was prepared.

Example 1 849.0 parts of the base resin (a-1) of Production Example 1, Production Example 3
364.0 parts of the curing agent (b) of Example 1 and 43.0 parts of the surface smoothing agent (c-1) of Production Example 8 are mixed to make ethylene glycol mono-2-ethylhexyl ether 3% based on the solid content. So added. Glacial acetic acid was added to this to neutralize it so that the neutralization rate was 40.5%, and ion-exchanged water was slowly added to dilute it, and methyl isobutyl ketone was removed under reduced pressure to obtain a solid content of 36.0%. The main emulsion of was obtained. 2,000 parts of this main emulsion, 460.0 parts of the pigment paste of Production Example 4, and ion-exchanged water 2
252 parts and 1% of dibutyltin oxide based on the solid content were mixed to obtain a cationic electrodeposition coating composition with a solid content of 20%.

Example 2 In Example 1, 744.0 parts of the base resin (a-1),
A cationic electrodeposition coating composition was obtained in the same manner as in Example 1 except that the curing agent (b) was changed to 319.0 parts and the surface smoothing agent (c-1) was changed to 214.0 parts.

Example 3 The base resin used in Example 1 was the same as in Production Example 2 (a-2).
A cationic electrodeposition coating composition was obtained in the same manner as in Example 1 except that the surface smoothing agent was changed to (c-2) in Production Example 9.

Example 4 The base resin used in Example 1 was the same as in Production Example 2 (a-2).
A cationic electrodeposition coating composition was obtained in the same manner as in Example 1, except that the surface smoothing agent was changed to (c-3) in Production Example 10.

Example 5 In Example 1, the surface smoothing agent was prepared in the same manner as in Production Example 11 (c-
A cationic electrodeposition coating composition was obtained in the same manner as in Example 1 except that the procedure (4) was changed.

Example 6 The base resin used in Example 1 was the same as in Production Example 2 (a-2).
A cationic electrodeposition coating composition was obtained in the same manner as in Example 1 except that the surface smoothing agent was changed to (c-5) of Production Example 12.

Comparative Example 1 In Example 1, the surface smoothing agent was added as in Production Example 13 (c-
A cationic electrodeposition coating composition was obtained in the same manner as in Example 1, except that the procedure in 6) was changed.

Comparative Example 2 In Example 1, the base resin was used as in Production Example 2 (a-2).
A cationic electrodeposition coating composition was obtained in the same manner as in Example 1, except that the surface smoothing agent was changed to (c-7) in Production Example 14.

Comparative Example 3 The base resin used in Example 1 was the same as in Production Example 2 (a-2).
In the same manner as in Example 1 except that the surface smoothing agent was changed to (c-8) in Production Example 15, a cationic electrodeposition coating composition was obtained.

Evaluation (1) The coating materials of Examples and Comparative Examples were electrodeposited on a cooled steel sheet treated with self-hazyl zinc phosphate conversion so as to give a dry film thickness of 20μ, washed with water and baked at 160 ° C. for 10 minutes. A cured coating film was obtained. 70
The number of craters on the coated surface per cm ² was visually counted. (2) Oil repellent Similarly to the above, electrodeposition was performed so that the dry film thickness was 20μ, followed by washing with water and air-drying at room temperature for 1 hour, then placing an aluminum cup in the center, in which ion-exchanged water and rust preventive oil (Knoxlast) were placed. ) For each 1
Use the dropper to add 160 drops as it is.
A cured coating film was obtained by baking at 10 ° C for 10 minutes. The degree of oil repellency of the obtained cured film was visually evaluated. ◯: Good Δ: Slight cissing occurred ×: Significant cissing occurred (3) Two-coat adhesion test The cured coating film obtained by the above method was spray-coated with an alkyd-based top coat paint to a dry film thickness of 35 μm. ,
The coating film obtained by baking at 140 ° C for 30 minutes has JIS
1mm x 1m according to K5400-1979 6.15
100 pieces of square stitches of m were made, a cellophane adhesive tape was adhered to the surface thereof, and the pieces were rapidly peeled off, and the number of residual stitches coating film was recorded. ◯: No peeling Δ: Peeling less than 10% X: Peeling more than 10% The results are shown in Table 1.

[0051]

[Table 1]

Claims (6)

[Claims] 1. A cationic electrodeposition coating composition obtained by dispersing (a) a hydrophilic film-forming resin having a cationic group and (b) a crosslinking agent in an aqueous medium containing a neutralizing agent.
(C) A plurality of blocks containing 10 to 90% by weight of a polyoxyalkylene chain having a number average molecular weight of 400 to 4000 in the molecule and blocked with a blocking agent selected from lactams, phenols, glycol ethers or oximes. A cationic electrodeposition coating composition comprising a polymer having an isocyanate group as a solid content in an amount of 1 to 35% by weight of a resin solid content of the entire composition. 2. The component (c) comprises an active hydrogen-containing group of polyoxyalkylene polyol, polyoxyalkylene polyamine or polyoxyalkylene polythiol,
The cationic electrodeposition coating composition according to claim 1, which is an adduct formed by an addition reaction of a partially blocked polyisocyanate compound with a residual free isocyanate group. 3. The component (c) is a secondary alcoholic product produced by ring-opening the epoxy ring of polyoxyalkylene polyol polyglycidyl ether by reaction with a compound containing a carboxyl group, a hydroxyl group or a thiol group. The cationic electrodeposition composition according to claim 1, which is an adduct obtained by subjecting a residual free isocyanate group of a partially blocked polyisocyanate compound to an addition reaction with a hydroxy group. 4. A copolymer of the component (c), which is an acrylic monomer having a blocked isocyanate group, an end-capped polyoxyalkylene glycol (meth) acrylate, and optionally other ethylenically unsaturated monomer. The cationic electrodeposition coating composition according to claim 1. 5. The component (a) comprises a part of an epoxy ring containing a plurality of oxazolidone rings in a resin skeleton which is a monoalcohol,
Ring-opening with at least one first active hydrogen compound selected from diols, monocarboxylic acids and dicarboxylic acids,
The cationic electrodeposition coating composition according to claim 1, obtained by ring-opening the remaining epoxy ring with a second active hydrogen compound capable of introducing a cationic group. 6. The cationic electrodeposition coating composition according to claim 1, wherein the component (b) is a blocked polyisocyanate compound.