JPH0211669A - Cationic electrodeposition composition - Google Patents

Abstract

PURPOSE:To obtain the title composition improved in low-temperature curability and shelf stability by neutralizing a mixture of a resin containing both a cationic group and an active hydrogen atom with a specified reaction product with an organic acid and dissolving or dispersing the resulting product in water. CONSTITUTION:An epoxy resin (e.g., bisphenol A epoxy resin) is reacted with a cationizing agent (e.g., diethanolamine) to obtain a resin (a) containing both a cationic group and an active hydrogen atom which becomes water-soluble when partially neutralized with an acid. Separately, an isocyanate or a polyisocyanate having allophanate and/or biuret structures is reacted with a blocking agent selected from among an oxime, acetylacetone, malonic diester and an acetoacetate to obtain a reaction product (b). Component (a) is mixed with 0.1-2.0 pts.wt., per pt.wt. solid matter of component (a), component (b) to obtain a mixture. This mixture is neutralized with an organic acid and dissolved or dispersed in water.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a cationic electrodeposition coating composition having excellent low-temperature hardening properties and coating stability.

[Problems to be solved by conventional technology and invention]

Conventional cationic electrodeposition coating has been widely used, mainly in the automobile industry, due to its excellent rust prevention, coating workability, economy, and low pollution properties.

The cationic electrodeposition coating compositions used in these applications usually contain a blocked incyanate blocked with alcohol or caprolactam as a curing agent.

However, isocyanates blocked with alcohol or caprolactam have baking temperatures of 150'C to 1
Since the baking temperature is as high as 80°C, the baking temperature has to be adjusted from the viewpoint of energy conservation, the need for electrodeposition coating on composite materials such as steel, rubber, and plastic, and the need for electrodeposition coating on high-tension steel and springs. Low temperature curability, that is, 120°C or less, is required.

In order to solve this problem, various low-temperature curable coating compositions have been studied, but cationic electrodeposition has sufficient coating performance when baked at temperatures below 120°C and has good coating stability. A coating composition has not yet been obtained.

[Means for solving problems]

In view of the above-mentioned circumstances, the present inventors conducted intensive studies and found that a block containing a cationic group and active hydrogen-containing resin that is water-dispersible when partially neutralized with an acid and a block that hardens at 60 to 120°C. We discovered that in combination with isocyanate, it is possible to achieve both low-temperature curability and paint stability.
The present invention has now been completed.

That is, the present invention provides a cationic group and active hydrogen-containing resin (component 1) that has water acidity when partially neutralized with an acid (component 1).
A cationic electrodeposition coating composition comprising a reaction product (component 2) of a polyisocyanate having an isocyanenurate, allophanate, and/or biuret structure and a blocking agent selected from oxime, acetylacetone, malonic acid diester, and/or acetoacetic ester. and a cationic group and active hydrogen-containing resin (component 1) that is water-dispersible when partially neutralized with an acid, a polyol having a triazine ring and/or a derivative thereof, a polyisocyanate, an oxime, acetylacetone, a malonic acid diester, and/or This is a cationic electrodeposition coating composition comprising a reaction product (component 3) with a blocking agent selected from acetoacetic esters.

Component 1 used in the present invention is, for example, a product obtained by reacting an epoxy group-containing tM fat with a cationizing agent, and/or a cationic group-containing α,β-unsaturated ethylene compound, an active hydrogen-containing αβ-unsaturated ethylene compound, and/or the like. Examples include copolymers consisting of a polymerizable ethylene compound.

Examples of the epoxy group-containing resin include polyepoxy resins synthesized from polyphenol compounds and epichlorohydrin, resins in which the terminals of polyalkylene oxide are plugged with epoxy, and epoxidized resins in which unsaturated ethylene groups are oxidized and epoxidized in a metal catalyst. Examples include one or a mixture of two or more of polybutadiene resins, copolymers of glycidyl (meth)acrylate and Ike's polymerizable ethylene compound, and the like.

Here, as polyphenols that can be used, for example,
bis(4-hydroxyphenyl)-2,2-propane,
Bis(4-hydroxyphenyl)-1,1-ethane, bis(4-hydroxyphenyl)methane, 4,4'-dihydroxybenzophenone, bis(4-hydroxy-ter
t-butylphenyl)-2,2-propane, tetra(
4-hydroxyphenyl)-1,1,2,2-ethane,
Examples thereof include 44'-dihydroxydiphenyl ether, phenol novolak, and cresol novolak.

The epoxy group-containing resin may be extended with polycarboxylic acid, polyamine, polyester polyol, polyether polyol, polyisocyanate, etc., if necessary.

The cationizing agent may be a primary or secondary cationizing agent containing an alkyl group, an aryl group, and/or an alkanol group.
amine, tertiary amine salt, secondary sulfide salt, tertiary amine salt,
Examples include class phosphine salts. Examples of these include methylamine, ethylamine, propylamine,
Primary amines such as benzylamine, monoethanolamine and propatoolamine; secondary amines such as diethylamine, dipropylamine, N-methylbenzylamine, N-methylethanolamine and jetanolamine;
Ethylenediamine, diethylenetonoamine, dimethylaminopropylamine, diethylaminopropylamine,
Hydroxyethylamine Polyamines such as ethylamine, a reaction product of hexamethylene diamine and Cardura E-10 (manufactured by Shell Ichigaku Co., Ltd.), a reaction product of tetraethylenetriamine and butyl glycidyl ether, etc., obtained by the reaction of a primary amine and a ketone. Examples include ketimine, which is
After reacting with the epoxy group-containing resin by a known method, these are neutralized with an acid, particularly preferably an organic carboxylic acid such as formic acid, acetic acid, or lactic acid, to become a cationic group. Furthermore, triethylamine', triethanolamine, N-N-
Dimethylethanolamine, N-methyljetanolamine, N,N-diethylethanolamine, etc., boric acid, carbonic acid, hydrochloric acid, etc. $! , organic acid or formic acid, acetic acid,
Contains lactic acid, propionic acid, etc. 8! Tertiary amine salt neutralized with acid, diethyl sulfide, diphenyl sulfide,
Tertiary sulfonium salts obtained by neutralizing 1,000 sulfur ethanol, etc. with the above acids; quaternary phosphonium salts obtained by neutralizing triethylphosphine, phenyldimethylphosphine, diphenylmethylphosphine, triphenylphosphine, etc. with the above acids. can be mentioned.

The epoxy group-containing resin is reacted with a cationizing agent by a known method to obtain the resin of component 1 of the present invention.

The above-mentioned cationic group-containing α, β-unsaturated ethylene (compounds include, for example, dimethylaminoethyl methacrylate, diethylaminoethyl di′-tacrylamide, dimethylaminostyrene, vinylpyridine, allylamine, hydroxyl group-containing acrylic monomer,
Examples include those made by reacting diisocyanate half-blocked with alkanolamine.

In addition, the active hydrogen-containing α,β-unsaturated ethylene monomers include, for example, carboxyl group-containing vinyl monomers such as acrylic acid and methacrylic acid, allyl alcohol, 2-
A hydroxyl group-containing vinyl monomer such as hydroxylethyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl methacrylate, etc., and a compound obtained by transesterifying such hydroxyl group-containing vinyl monomer with ethyl acetoacetate, dimethyl malonate, etc., ε
- Examples include chemical products obtained by polymerizing caprolactone.

Examples of the polymerizable ethylene compounds mentioned above include (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and stearyl (meth)acrylate. Acid esters, styrene vinyl toluene, vinyl acetate, vinyl salt C, vinyl f compounds such as vinyl fluoride, vinylidene compounds such as vinylidene fluoride and vinylidene chloride, butadiene, pentagene,
Examples include coumaron and indene.

Using such a compound, a conventional radical polymerization reaction is carried out at room temperature to 200° C. using a radical polymerization initiator such as azobisisobutyronitrile, dicumyl peroxide, t-butyl peroxide, etc. to obtain the resin of component 1 of the present invention. Get it.

In this reaction, a solvent such as toluene, xylene, ethyl cellosolve, butyl cellosolve, methyl isobutyl ketone, or a chain transfer agent such as n-dodecyl mercaptan or mercaptopropionic acid may be used as necessary.

What is used as component 2 of the present invention is 2 molecules or 3 or more molecules of diisocyanate-1.
Polyurethane or polyol which has a biuret bond, an allophanate bond, an isocyanurate bond in its molecule and has two or more active isocyanurate bonds and has two or more active isocyanate groups. and a mixture of one or more polyisocyanate compounds comprising a diisocyanate as described above, having a urethane bond in the molecule, and having two or more active isocyanate groups, and an oxime as a blocking agent.
It is obtained by reacting acetylacetone with malonic acid ester and/or acetoacetic acid ester.

Examples of the diisocyanate include hexamethylene diisocyanate, diphenylmethane diisocyanate, toluene diisocyanate, xylene diisocyanate, isophorone diisocyanate, and the like.

Examples of the oxime include methyl ethyl ketoxime, methyl isobutyl ketoxime, acetoxime, 2-butanone oxime, propatool oxime, and the like.

Examples of the malonic acid diester include methyl ethyl malonate, dimethyl malonate, dibutyl malonate, and the like.

Further, examples of the acetoacetate include methyl acetoacetate, ethyl acetoacetate, butyl acetoacetate, and the like.

Component 3 of the present invention is a reaction product consisting of a polyol containing a triazine ring and/or its derivatives such as cyanuric acid, isocyanurate, melamine, etc., and the aforementioned polyisocyanate and blocking agent. Examples of polyol compounds containing such a triazine ring and its derivatives include tris-2-hydroxyethyl isocyanurate, a reaction product of trisglycidylethyl isocyanurate and acrylic acid, and the like.

Such an isocyanate and a substance capable of reacting with incyanate are reacted at room temperature to 200°C in the presence of an inert organic solvent such as toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, isophorone, dioxane, etc. to form component 2 and inocyanate of the present invention. Get 3. In this reaction, a catalyst such as a tertiary amine may be used as necessary.

The medium amount of C in component 2 or 3 of the present invention may be an amount sufficient to remove the coating and react with hydroxyl groups, amino groups, etc. in the resin when baking the electrodeposition coating film, and component 1. It is preferably 0.1 to 2.0 parts per part of solid content.

To prepare the composition for cationic electrodeposition coating of the present invention, component 1 and component 2 or component 3 are mixed, and this is mixed with an appropriate acid, for example, an inorganic acid such as boric acid, philic acid, sulfuric acid, hydrochloric acid, formic acid,
After neutralization with an organic acid such as acetic acid or lactic acid, preferably an organic acid alone or in combination, it is dissolved or dispersed in water.

In the composition for cationic electrodeposition coating according to the present invention, conventional additives such as pigments, solvents, surfactants, etc. may be appropriately added to the above-mentioned components.

Any conventional pigment may be used, such as inorganic pigments such as iron oxide, carbon black, titanium dioxide, clay, talc, barium sulfate, cadmium yellow, cadmium red, lead chromate, strontium chromate, phthalocyanine blue, Examples include organic pigments such as phthalocyanine green.

In the electrodeposition method using the composition of the invention, the composition of the invention is brought into contact with an electrically conductive anode and an electrically conductive cathode (having the surface to be coated), usually at a voltage of 10 to 500 V.
A voltage is applied to deposit a coating film on the cathode surface. Electrodeposition conditions may vary widely, but are generally those known in the art. After electrodeposition coating, e.g. 130°
C or less, preferably 60 or less The present invention will be specifically explained by giving examples of the present invention.

All parts in the examples are parts by weight.

Production example 1 (component 1) 4'I! 951 parts of propylene glycol methyl ether and 1900 parts of bisphenol A type epoxy resin with an epoxy equivalent of 475 were placed in a χ4 Tulo flask, heated and dissolved, and then 200 parts of jetanolamine and 120 parts of ethyl aminopropylamine were added at 60°C, and the mixture was heated at 120°C. The mixture was heated to a temperature of 100.degree. C., reacted for 3 hours, cooled to room temperature, and then taken out to obtain a base resin A.

Manufacture @2 (Component 1) 3 ￥Z 4 626 parts of propylene glycol methyl ether and 13011 parts of EPU-3 (Asahi Denka (working urethane-modified epoxy resin) were placed in a turf flask and dissolved by heating at f&60°C to obtain 100 parts of jetanolamine. 1 part, 60 parts of diethylaminopropylamine were added, and the mixture was heated at 120°C for 3 parts.
The reaction mixture was allowed to react for a period of time, and after cooling to room temperature, it was taken out to obtain base resin B.

Production Example 3 (Component 1) 960 parts of propylene glycol methyl ether and Nisseki Polybutadiene E-1800-6 were placed in a 3-4 tube flask.
, 5 (Japan Petrochemical (F@-type epoxidized polybutadiene) 1800 parts was charged, heated while mixing, and added 210 parts of jetanolamine at 60°C. After reacting at 160°C for 4 hours, 240 parts of castor oil fatty acid was added. , 4 parts of hydroquinone were added thereto, and the mixture was allowed to react at 160°C for an additional 4 hours.Then, the mixture was cooled to room temperature and taken out to obtain a base resin C.

Production example 4 (component 1) 3 yen;, 4 tube flasks, 20 isopropanol
0 parts and 443 parts of ethyl cellosolve were charged and refluxed at 105°C. To this, 870 parts of methyl methacrylate, 300 parts of hydroxyethyl methacrylate, 150 parts of acrylamide, 18 parts of dimethylaminoethyl methacrylate.
3 parts of a mixture of 0 parts and 30 parts of azobisisobutyronetrile.
Dropwise over a period of time to perform radical polymerization. then 10
After being maintained at 5°C for 3 hours, it was cooled to room temperature and taken out to obtain a base resin.

Production Example 5 (Component 2) 2': 206 parts of xylene, 206 parts of dioxane, and 522 parts of isocyanurate-type trimer of tolylene diisocyanate-1 were placed in a 2': Z 4 flask, and 261 parts of methyl ethyl ketoxime was added at 20°C. Drip over time. After that, the mixture was reacted at 60°C for 3 hours, and then 10 parts of butyl cellosolve was added, and the mixture was reacted at 60°C for 1 hour.

Curing agent A was obtained. The content of unreacted isocyanate groups in this product was 0%.

Production example 6 (component 2) 2'? ; 410 parts of xylene and 504 parts of a piure-nod type trimer of hexamethylene diisocyanate were placed in a C4 tube flask, and while stirring, 480 parts of diethyl malonate was added.
1 part and 20 parts of dibutyl octadilaurate, and heated to 120°C.
After reacting for 6 hours, 100 parts of butyl cellosolve was added and the mixture was further reacted at 120° C. for 1 hour to obtain abrasive agent B. The content of unreacted incyanate groups in this product was 0%.

Production Example 7 (Component 2) 2 yen; 720 parts of xylene, 720 parts of methyl isobutyl ketone, and 666 parts of isocyanurate type trimer of isophorone diisocyanate are charged into a 4-meter flask and dissolved with stirring. To this, 348 parts of acetoacetic acid methyl ester and 20 parts of dibnaltin dilaurate were added and reacted at 100"C for 4 hours. Then, 100 parts of methanol was added and an additional 100 parts of methanol was added.
Curing agent C was obtained by reacting at 0° C. for 1 hour.

Production Example 8 (Component 3) 898 parts of toluene and Plaxel 3 in a 3-roofed 4-walled flask
08 (Polycaprolact manufactured by Daicel Chemical Co., Ltd.) 800 parts of Triol TL fat and 522 parts of tolylene diisocyanate were added dropwise to react at 80°C for 1 hour with stirring to obtain a hardened shavings.Unreacted isocyanate group content of this product was 0%.

Production Example 9 (Component 3) Methyl isobutyl ketone 643 in a 2" α4 flask
390 parts of ethyl acetoacetate and 10 parts of dibutyl dilaurate were added under stirring, and the mixture was reacted at 80° C. for 2 hours. 300 parts of xamethylolated melamine was added to the mixture and reacted at 80°C for an additional 2 hours to obtain a curing agent E.

Production Example 10 (Component 3) 2:Z 490 parts of xytone, 504 parts of hexamethylene diisocyanate, 213 parts of trishydroxyethyl isocyanurate, and 7 parts of dibutyltin dilaurate were charged into a z 4 tube flask, and reacted at 90° C. for 4 hours. Thereafter, 350 parts of acetylacetone was added and reacted at 120°C for 4 hours to obtain a curing agent F. The unreacted isocyanate group content of this product was measured and found to be Q%.

Production Example 11 (Conventional hardening agent) 486 parts of toluene, 522 parts of tolylene diisocyanate, and 339 parts of ε-caprolactam in a 2° 474-meter flask.
134 parts of trimethylolpropane and heated to 60°C.
After reacting for 6 hours, 50 parts of butyl cellosolve was added and reacted at 90°C for 1 hour to obtain curing agent G3.

Examples 1 to 7 and Comparative Examples 1 to 3 To the base resin and curing agent in the amounts shown in Table 1, 2 parts of carphone black, 20 parts of titanium oxide, 15 parts of kaolin, and 1 part of dibutyltin dilaurate. After adding and thoroughly mixing 1.6 parts of formic acid and dispersing for 30 minutes using a three-roll mill, 600 parts of deionized water was gradually added and emulsified while stirring with a day silver to obtain an electrodeposition paint.

Using this paint, cationic electrodeposition coating was applied to an iron plate treated with zinc phosphate by a known method, and the coating properties shown in Table 1 were obtained.

[ Effect of the invention〕

The electrodeposition paint of the present invention can be baked sufficiently even at a low temperature of about 120° C., and has excellent paint bath stability, so it is suitable for a low temperature curing type with a cationic electrodeposition value of ↑.

Patent applicant Shinto Paint Co., Ltd.

Claims (1)

[Scope of Claims] 1. A resin containing a cationic group and active hydrogen that is water-dispersible when partially neutralized with an acid (component 1), and a polyisocyanate having an isocyanenurate, allophanate, and/or biuret structure; oxime, acetylacetone,
A cationic electrodeposition coating composition comprising a reaction product (component 2) with a blocking agent selected from malonic diesters and/or acetoacetic esters. 2. A cationic group and active hydrogen-containing resin (component 1) that is water-dispersible when partially neutralized with an acid, a polyol having a triazine ring and/or its derivative, a polyisocyanate, an oxime, acetylacetone, a malonic acid diester, and or a reaction product (component 3) with a blocking agent selected from acetoacetate.