JPH0860047A - Cationic electrodeposition coating composition - Google Patents

Abstract

PURPOSE: To obtain a cationic electrodeposition coating compsn. which can form a coating film excellent in weathering resistance ad corrosion resistance. CONSTITUTION: This compsn. contains an amine adduct (I) of a polyurethane- modified epoxy resin and a nonionic film-forming resin (II) in a wt. ratio of I to II of (15:85)-(95:5). The component (I) is produced by reacting a polyurethane compd. having one terminal isocyanate group in the molecule, a disphenol epoxy resin having at least two epoxy group in the molecule, and an amine compd. having active hydrogen atoms. The polyurethane compd. is formed by reacting a polyhydroxy compd. having a number-average mol.wt. of 50-8,000, a polyisocyanate compd., and a compd. having one active hydrogen atom in the molecule.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel electrodeposition coating composition, and more particularly to a cationic electrodeposition coating composition capable of forming a coating film having excellent weather resistance and corrosion resistance.

[0002]

2. Description of the Related Art As a cationic electrodeposition coating composition, a composition obtained by mixing a block polyisocyanate compound as a curing agent with an amine-added epoxy resin obtained by a reaction between an epoxy resin and an amino compound containing active hydrogen has hitherto been used. Is used. The coating film formed by using this composition has excellent corrosion resistance, but has a drawback that the weather resistance is not sufficient.

In order to improve the weather resistance, it has been proposed to modify the epoxy resin with a polyester resin, a polyether resin, an acrylic resin or the like, whereby the weather resistance of the coating film is slightly improved. However, there is a problem that the anticorrosion property which is a characteristic of the epoxy resin is lowered.

In addition, in the case of modifying an epoxy resin with an acrylic resin, it is difficult to sufficiently carry out the modification reaction itself due to the poor compatibility of these two components, and the viscosity of the resulting modified product is also high. Has the drawback of being high.

[0005]

Means for Solving the Problems The inventors of the present invention have earnestly studied for the purpose of developing an electrodeposition coating composition capable of forming a coating film having both excellent corrosion resistance and weather resistance. It was found that the above object can be achieved by using a specific polyurethane resin for modification and using it together with a nonionic film-forming resin such as an acrylic resin or a polyester resin, and completed the present invention. .

Therefore, according to the present invention, I. (A) a polyhydroxy compound (a) having a number average molecular weight of 50 to 8000, a polyisocyanate compound (b),
And a polyurethane compound having one terminal isocyanate group in one molecule obtained by the reaction of the compound (c) having one active hydrogen in one molecule, (B) at least two epoxy groups in one molecule A bisphenol type epoxy resin having the same, and (C) a polyurethane-modified amine-added epoxy resin formed by the reaction of an amine compound containing active hydrogen, II. Resin I / Resin II
A cationic electrodeposition coating composition is provided in which the weight ratio thereof is within the range of 15/85 to 95/5.

The cationic electrodeposition coating composition of the present invention will be described in more detail below.

I. Polyurethane modified amine-added epoxy
Resin polyurethane compound (A): Polyurethane compound (A)
Is a polyurethane compound having one terminal isocyanate group in one molecule obtained by the reaction of the polysidoxy compound (a), the polyisocyanate compound (b) and the compound (c) having one active hydrogen in one molecule. Yes,
Generally from 400 to 10,000, preferably from 1,000
It is desirable to have a number average molecular weight in the range of 4,000.

The polyhydroxy compound (a) has at least two alcoholic hydroxyl groups in one molecule and has a number average molecular weight of 50 to 8,000, particularly 50 to 6,
It can be used without particular limitation as long as it is in the range of 000, and examples thereof include various polyester polyols or polyether polyols and mixtures thereof which are usually used in the production of polyhydric alcohols or polyurethane resins. To be

Examples of the above polyhydric alcohols include ethylene glycol, propylene glycol, butanediol, diethylene glycol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, N-methyl-diethanolamine and N-ethyl. -Dihydric alcohols such as diethanolamine; trihydric alcohols such as glycerin, trimethylolpropane and triethanolamine;
Examples thereof include tetrahydric alcohols such as pentaerythritol.

As the polyester polyol, a condensate of polyhydric alcohol and polybasic carboxylic acid,
Examples thereof include a condensation product of a hydroxycarboxylic acid and a polyhydric alcohol, and a product obtained by ring opening of a cyclic lactone. Examples of the polyhydric alcohol used here include those described above, and examples of the polybasic carboxylic acid that can be condensed with this include adipic acid, azelaic acid, dimer acid, glutaric acid, and pyromellitic acid. Examples of the hydroxycarboxylic acid include dimethylolpropionic acid and the like. As the condensate of hydroxycarboxylic acid and polyhydric alcohol, castor oil, castor oil and a reaction product of ethylene glycol, propylene glycol and the like can also be used.

Further, as the polyether polyol, for example, ethylene oxide, propylene oxide,
It is a product obtained by addition-polymerizing one or more alkylene oxides such as butylene oxide and tetrahydrofuran to a compound having two or more active hydrogens, and is a polyether polyol known per se which is usually used for producing a polyurethane resin. Either can be used. Examples of the compound having two or more active hydrogens that can be used for producing the polyether polyol include, for example, the above-mentioned polyhydric alcohol and polybasic carboxylic acid, amines such as ethylenediamine and hexamethylenediamine; ethanolamine, Alkanolamines such as propanolamine; polyvalent phenols such as bisphenol; castor oil and the like.

The above-mentioned polyhydroxy compound (a)
Can be used alone or in combination of two or more as long as the number average molecular weight is in the range of 50 to 8,000. The polyisocyanate compound (b) used for producing the polyurethane compound (A) is a compound having two or more, preferably 2 or 3 isocyanate groups in one molecule, and those generally used for producing a polyurethane resin are Can be used as well. Examples of such polyisocyanate compound (b) include aliphatic, alicyclic, and araliphatic polyisocyanate compounds,
Typically, the following can be exemplified.

Hexamethylene diisocyanate (HMD
I), biuret compounds of HMDI, aliphatic polyisocyanate compounds such as isocyanurate compounds of HMDI; isophorone diisocyanate (IPDI), IP
Alicyclic polyisocyanate compounds such as biuret compounds of DI, isocyanurate compounds of IPDI, hydrogenated xylylene diisocyanate and hydrogenated 4,4'-diphenylmethane diisocyanate; aromatic aliphatic compounds such as tolylene diisocyanate and xylylene diisocyanate -Based polyisocyanate compounds.

These may be used alone or in combination of two or more. The compound (c) having one active hydrogen in one molecule used for producing the polyurethane compound (A) is used for blocking the isocyanate group in the polyisocyanate compound (b). It is preferable to use a compound which dissociates from a blocked isocyanate group to give a free isocyanate group at the baking temperature (usually 120 to 200 ° C., preferably 160 to 180 ° C.) of the coating film of the formed cationic electrodeposition coating composition. it can.

Examples of such active hydrogen-containing compound (c) include monohydric alcohols such as methanol, ethanol and diethylene glycol monobutyl ether; monovalent carboxylic acids such as acetic acid and propionic acid; monovalent thiols such as ethyl mercaptan; Secondary amines such as diethylamine; diethylenetriamine, monoethanolamine and other secondary amino groups or primary amino groups of amine compounds containing hydroxyl groups and one or more primary amino groups, ketones, Examples thereof include compounds that have been modified into aldimine, ketimine, oxazoline or imidazoline by heating reaction with aldehyde or carboxylic acid at a temperature of 100 to 230 ° C .; oximes such as methylethylketoxime and the like. It is desirable that these active hydrogen-containing compounds (c) generally have a molecular weight in the range of 30 to 2,000, especially 30 to 200.

The polyhydroxy compound (a), the polyurethane compound (b) and the active hydrogen-containing compound (c) described above are reacted with each other to give the polyurethane compound (A). The reaction ratio of is generally within the following range based on the total amount of the components (a), (b) and (c), and is therefore appropriate.

Polyhydroxy compound (a): 10 to 94
% By weight, preferably 30-80% by weight, polyisocyanate compound (b): 5-80% by weight, preferably 10-60% by weight, active hydrogen-containing compound (c): 1-85% by weight, preferably 1- 60% by weight.

The polyhydroxy compound (a),
There are no particular restrictions on how to react the polyisocyanate compound (b) and the active hydrogen-containing compound (c), and for example,
Method of mixing three components (a), (b) and (c) and reacting them simultaneously; a method of reacting the component (b) and the component (c) in advance, and then reacting the product with the component (a) Is mentioned. Regardless of which method is used for the reaction, the reaction ratio and / or the reaction sequence of each component is adjusted so that the resulting polyurethane compound has one terminal isocyanate group in one molecule.

Of the above methods, the method is preferred, and specifically, the polyisocyanate compound (b) and the active hydrogen-containing compound (c) are added to the compound (c) per one isocyanate group of the compound (c). The hydrogen-containing group is 1 equivalent or less, preferably 0.5 equivalent or less, more preferably 0.1.
A block polyisocyanate compound is produced by reacting at a ratio of 7 equivalents or less until substantially no unreacted active hydrogen-containing group is present, and then the polyhydroxy compound (a) is added to the compound (b) in an isocyanate equivalent amount of the compound. (A) and compound (c) are blended so as to increase by 1.0 with respect to the total of the hydroxyl group equivalent and the active hydrogen equivalent, and the reaction is carried out to such an extent that the hydroxyl group is substantially not detected. ) Can be manufactured.

In the above reaction, if necessary, a known catalyst for urethane synthesis, for example, a tertiary amine such as triethylamine; an organometallic compound such as dibutyltin dilaurylate, or the like can be used. .

The polyurethane compound (A) thus obtained has one terminal isocyanate group in one molecule, and its number average molecular weight is 400 to 10,0.
00, preferably 1,000 to 4,000. If the number average molecular weight is less than 400, the flexibility is lowered, while if it is more than 10,000, the coated surface smoothness is lowered, which is generally not preferable.

Bisphenol type epoxy resin (B): The bisphenol type epoxy resin (B) is a bisphenol type compound having at least two epoxy groups in one molecule, and particularly, a bisphenol type compound and epihalohydrin. For example, a diglycidyl ether of bisphenol, which is obtained by a condensation reaction with epichlorohydrin, is suitable because a coating film having excellent flexibility and anticorrosion property can be easily obtained.

Representative examples of the bisphenol compound that can be used for preparing the epoxy resin (B) are bis (4-hydroxyphenyl) -2,2-propane and bis (4-hydroxyphenyl) -1,2. 1-ethane, bis (4-hydroxyphenyl) -methane, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, bis (4-hydroxyphenyl) -1,1-isobutane, Examples thereof include bis (4-hydroxy-3-t-butylphenyl) -2,2-propane.

Among the epoxy resins (B) formed using such bisphenol compounds, bisphenol A type diglycidyl ether represented by the following formula is flexible,
It is particularly suitable in that it gives a coating film having excellent anticorrosion properties.

[0026]

Embedded image

In the formula, q is a number of 2 to 20.

As an epoxy resin (B), an excess amount of diglycidyl ether of bisphenol obtained by a condensation reaction of a bisphenol compound and epihalohydrin is further etherified with a bisphenol compound. Those obtained can also be used suitably.

The epoxy resin (B) used in the present invention is
It is generally preferred to have a number average molecular weight within the range of about 310 to about 10,000, especially about 320 to about 2,000, and the epoxy equivalent weight is about 155 to about 5,000.
It is preferably in the range of 0, especially about 160 to about 1,000.

Active hydrogen-containing amino compound (C): The active hydrogen-containing amino compound (C) is an amino compound having active hydrogen capable of reacting with an epoxy group and is an aliphatic, alicyclic or araliphatic type compound. Primary or secondary amines or alkanolamines or modified products thereof, tertiary
Primary amine salts and the like are included. Examples of these amine compounds having active hydrogen include the following.

(1) First of amine compounds containing one secondary amino group and one or more primary amino groups, such as diethylenetriamine, hydroxyethylaminoethylamine, ethylaminoethylamine and methylaminopropylamine. The primary amino group is combined with a ketone (eg, acetone, methyl ethyl ketone, etc.), an aldehyde (eg, acetaldehyde, propionaldehyde, etc.) or a carboxylic acid (eg, acetic acid, propionic acid, etc.), for example, 100 to 2
By reacting by heating at a temperature of 30 ° C, aldimine,
Compounds modified with ketimine, oxazoline or imidazoline; (2) diethylamine, diethanolamine, di-n-
Or secondary monoamines such as iso-propanolamine, N-methylethanolamine and N-ethylethanolamine; (3) monoalkanolamines such as monoethanolamine and dialkyl (meth) s such as dimethyl (meth) acrylamide. Secondary amino group-containing compound obtained by addition of acrylamide with Micheal addition reaction; (4) Monoethanolamine, neopentanolamine, 2-aminopropanol, 3-aminopropanol, 2-hydroxy-2 '-( (5) dimethylethanolamine, triethylamine, a compound obtained by modifying the primary amino group of an alkanolamine such as aminopropoxy) ethyl ether into a ketimine;
Salts of tertiary amines such as trimethylamine, triisopropylamine and methyldiethanolamine with organic acids such as acetic acid and lactic acid.

Of these, the compounds of the above groups (1), (2) and (4) are preferable, and among them, after the secondary amino group such as diethanolamine or ketimine compound of diethylenetriamine reacts with the epoxy group, Those which further have an active hydrogen group or which can have an active hydrogen group by hydrolysis of ketimine have a cross-linking functional group and are particularly preferable.

Polyurethane-modified amine-added epoxy resin
Fat: The polyurethane-modified amine-added epoxy resin contained in the cationic electrodeposition coating composition of the present invention as an essential component is
For example, it can be obtained by reacting the above-mentioned polyurethane compound (A) with a bisphenol type epoxy resin (B) to obtain a polyurethane-modified epoxy resin, and then adding an active hydrogen-containing amine compound (C). it can.

As the reaction for obtaining the polyurethane-modified amine-added epoxy resin, for example, the secondary hydroxyl group in the bisphenol type epoxy resin (B) is reacted with the polyurethane compound (A), and then the obtained polyurethane-modified epoxy resin is obtained. The method of adding the active hydrogen-containing amine compound (C) to the terminal oxirane group of the resin is particularly preferable from the viewpoint of resin design and control. However, the addition of the active hydrogen-containing amine compound (C) is the same as that of the polyurethane-modified epoxy resin. It can also be performed simultaneously during manufacturing. The reaction between the active hydrogen-containing amino compound (C) and the epoxy group of the epoxy resin (B) can be carried out, for example, by reacting at a temperature of about 30 to about 160 ° C. for about 1 to about 5 hours. .

The reaction ratio of each component of the polyurethane compound (A), the epoxy resin (B) and the active hydrogen-containing amino compound (C) can be varied over a wide range according to the purpose, but in general, Based on the total amount of the three components of the polyurethane compound (A), the epoxy resin (B) and the active hydrogen-containing amino compound (C), the polyurethane compound (A) is in the range of 16 to 80% by weight, particularly 50 to 70% by weight. It is preferable to use it inside. The epoxy resin (B) is 20 to 84% by weight, especially 30 to 50% by weight.
It is preferable to use it within the range. Further, the active hydrogen-containing amino compound (C) is preferably used in an amount such that the resulting polyurethane-modified amine-added epoxy resin has an amine value of 15 to 100, particularly 15 to 47.

The polyurethane-modified amine-added epoxy resin to be formed generally preferably has a number average molecular weight in the range of 1,000 to 20,000, particularly 2,400 to 4,000.

The polyurethane-modified amine-added epoxy resin preferably contains a primary hydroxyl group, and although the range of the primary hydroxyl group equivalent is not particularly limited, it is usually 600 to 1,000, particularly 600 to 850. The range of is preferable. The primary hydroxyl group provided by the active hydrogen-containing amino compound (C) and the like, the secondary hydroxyl group present in the epoxy resin (B) portion, etc. serve as a reactive functional group with the crosslinking agent.

The polyurethane-modified amine-added epoxy resin is also reacted with a reaction agent such as a tertiary amine salt, a monocarboxylic acid, a secondary sulfide salt, a monophenol or a monoalcohol to give a water-dispersible resin. It is also possible to make adjustments and improve the smoothness of the coating film.

Further, a crosslinkable functional group such as a block isocyanate group, a β-hydroxycarbamic acid ester group, an α, β-unsaturated carbonyl group and an N-methylol group is further introduced into the polyurethane-modified amine-added epoxy resin. Therefore, the internal crosslinkability can be improved.

The above reaction with the reaction reagent and the introduction of the crosslinkable functional group may be carried out before the addition of the active hydrogen-containing amino compound (C) to the polyurethane-modified epoxy resin.

II. Nonionic film-forming resin: polyurethane-modified amine-added epoxy resin (resin I) described above
The nonionic film-forming resin (resin II) used in combination with a functional group (eg, carboxyl group) capable of forming an ionic group (cationic group and anionic group) by neutralization with an acid or a base. Group, amino group, etc.) and is capable of forming a continuous film under the baking conditions of the electrodeposition coating film, which itself is a thermoplastic resin, which resin may optionally be as described above. It may contain a functional group (for example, a hydroxyl group, an epoxy group, etc.) capable of reacting with the external crosslinking agent.

The resin II generally has a number average molecular weight of about 3,000 to 100,000, preferably about 4,000.
It is desirable that it is in the range of 0 to 50,000 and has a non-ionic functional group (for example, a hydroxyl group) capable of undergoing a crosslinking reaction with the blocked isocyanate group of the resin I or the external curing agent in the molecule during bake curing.

As the resin II having the above-mentioned characteristics, specifically, acrylic resin, polyester resin, polyester modified acrylic resin, acrylic modified polyester resin, silicon modified resin and the like having excellent weather resistance are preferable. It can be illustrated as

Hereinafter, these preferable resins II will be described more specifically.

Examples of the nonionic acrylic resin include (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, propyl (meth) acrylate and 2-ethylhexyl (meth) acrylate. Alkyl ester of acrylic acid;
A hydroxyalkyl ester of (meth) acrylic acid such as hydroxyethyl (meth) acrylate or hydroxypropyl (meth) acrylate; mainly containing one or more acrylic monomers selected from glycidyl (meth) acrylate, And other unsaturated monomers, for example, vinyl aromatic compounds such as styrene and α-methylstyrene, depending on the desired physical properties of the resulting resin;
(Meth) acrylonitrile, (meth) acrylamide;
Acrylic obtained by appropriately selecting one or more selected from olefins such as ethylene and propylene; dienes such as butadiene and isoprene; vinyl acetate and the like, and (co) polymerizing according to a conventional method. Examples include resin.

It is desirable that the acrylic resin contains 25% by weight or more, especially 35% by weight or more of the unit derived from the acrylic monomer, and the acrylic resin has a number average molecular weight of About 3,000 to about 100,000
Those in the range of 0, preferably in the range of about 4,000 to about 50,000 are suitable. When the acrylic resin contains a hydroxyl group as a functional group, it can be crosslinked and cured by reacting with the block isocyanate group in the resin I or the block polyisocyanate compound as an external crosslinking agent.

Nonionic polyester resins which can be used as the resin II include, for example, phthalic acid and its acid anhydride, isophthalic acid, terephthalic acid, trimellitic acid and its acid anhydride, pyromellitic acid and its acid anhydride,
Hexahydrophthalic acid and its acid anhydride, succinic acid,
Polybasic acid components such as adipic acid, pimelic acid, sebacic acid, brassylic acid, and ethylene glycol, diethylene glycol, propylene glycol, neopentyl glycol, 1,6-hexanediol, trimethylolpropane, glycerin, pentaerythritol, tricyclodetylene It includes a polyester resin having no terminal carboxyl group, which can be produced by condensation-condensation with a polyol component such as candimethanol according to a conventional method. At that time, as a terminal blocking agent, for example, benzoic acid, pt
-Butylbenzoic acid and the like can be used to control the molecular weight.

The polyester resin is generally 3,000
To 100,000, preferably 4,000 to 50,000
It can have a number average molecular weight in the range of.

As the resin II, the above acrylic resin and polyester resin may be blended and used. Alternatively, a polyester modified acrylic resin obtained by modifying (grafting) the above acrylic resin with polyester, an acrylic modified polyester resin obtained by modifying (grafting) the above polyester resin with an acrylic resin, etc.
It can be used as I.

Further, the nonionic silicone-modified resin which can be used as the resin II includes a suitable base resin, for example, an acrylic resin or polyester resin as described above, or an alkyd resin modified with a silicone resin. Generally, the amount of silicone resin used is 50
It is suitable to be less than or equal to wt%, preferably within the range of 3 to 45 wt%.

The silicone resin used for modifying the base resin usually has a reactive group such as a hydroxyl group or an alkoxy group in the molecule, the number average molecular weight of which is preferably in the range of about 500 to about 2,000. An organopolysiloxane resin having two or more, such as Z-6018 (Dow Cornin
g company product, molecular weight 1,600), Z-6188 (Dow Cor
ning products, molecular weight 650), Sylkyd 50,
DC-3037 (Dow Corning product), KR-21
6, KR-218, KSP-1 [Shin-Etsu Silicone Co., Ltd.
Products], TSK-160, TSR-165 [Tokyo Shibaura Electric Co., Ltd. products], SH5050, SH6018, SH6
A commercially available product such as 188 [product of Toray Silicone Co., Ltd.] can be used.

The silicon-modified resin is obtained by co-condensing the above-mentioned silicone resin and a base resin having a hydroxyl group and / or a carboxyl group, such as an acrylic resin, a polyester resin, etc., in the above-mentioned use ratio by a method known per se. It can be manufactured.

Among the resins exemplified above, the polyester-modified nonionic acrylic resin is particularly preferable because it has good compatibility with the urethane-modified amine-added epoxy resin and the cross-linking functional group can be easily introduced.

Cationic electrodeposition coating composition: The cationic electrodeposition coating composition of the present invention is prepared by dissolving or dispersing Resin I and Resin II described above in an aqueous medium by a method known per se. be able to.

For example, Resin I and Resin II are dissolved in a water-miscible organic solvent and mixed with water and an acid (for example, water-soluble organic acid or inorganic acid such as acetic acid, formic acid, lactic acid, phosphoric acid, sulfuric acid). To form an aqueous bath or to disperse Resin I in an aqueous medium and neutralize with an acid as described above to form an aqueous bath, in which water-miscible organic solvent of Resin II is added. The solution can be prepared by a method such as forced dispersion using a homogenizer or the like. In the composition obtained by any of the above methods and, the particles of Resin II are extremely stably dispersed in water by the acid-neutralized product of Resin I, and have excellent storage stability over a long period of time. Indicates.

In the preparation of the electrodeposition coating composition of the present invention, Resin I and Resin II may be used alone or in combination of two or more kinds. The mixing ratio of the resin I and the resin II can be changed according to the type of each resin and the desired characteristics of the electrodeposition coating, but in general, the resin I
The weight ratio of / resin II may be within the range of 15/85 to 95/5, preferably 50/50 to 90/10. When the blending ratio is outside the above range, it is difficult to obtain a multilayer film having an effective concentration gradient, and weather resistance and corrosion resistance tend to be poor.

In the electrodeposition coating composition of the present invention, in addition to the resin I and the resin II described above, a coloring pigment, an anticorrosive pigment, an extender pigment, which are usually used in the field of coatings, may be added as needed.
A curing catalyst, a surfactant, and other additives can also be added. Further, as an external cross-linking agent, a cross-linkable functional group is added
You may mix | blend the compound which has two or more in a molecule | numerator, for example, block polyisocyanate, polyamine β-hydroxycarbamic acid ester, malonic acid ester, malonic acid ester derivative, methylolated melamine, methylolated urea and the like. The amount of these external cross-linking agents to be compounded is generally 100 by weight ratio of (resin I + resin II) / external cross-linking agent.
/ 0-60 / 40, preferably 85 / 15-75 / 25
It is desirable to be within the range. As a method and apparatus for performing electrodeposition coating on an article using the electrodeposition coating composition of the present invention, known methods and apparatuses conventionally used per se in cationic electrodeposition coating can be used. . At this time, it is desirable to use the object to be coated as the cathode and use the stainless steel or carbon plate as the anode. The electrodeposition coating conditions that can be used are not particularly limited, but in general,
Bath temperature: 20 to 30 ° C., voltage: 100 to 400 V (preferably 200 to 300 V), current density: 0.01 to 3 A /
dm ² , energization time: 1 to 5 minutes, pole area ratio (A / C): 2
/ 1 to 1/2, distance between electrodes: 10 to 100 cm, and electrodeposition in a stirred state is desirable.

The coating film deposited on the object to be coated on the cathode can be baked and cured at about 140 ° C. to about 180 ° C. after cleaning.

[0059]

ACTION AND EFFECT Since the polyurethane-modified amine-added epoxy resin used in the cationic electrodeposition coating composition of the present invention is modified with a specific polyurethane resin, there are a polyurethane-modified epoxy resin and an unmodified epoxy resin in the coating film. It is possible to form a coating film having excellent compatibility, excellent weather resistance, corrosion resistance and appearance.

[0060]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. In addition, "%" means "weight%" below.

I. Sample 1. Production of polyurethane-modified amine-added epoxy resin In a flask equipped with a stirrer, a thermometer, a nitrogen inlet tube and a reflux condenser, 666 g of isophorone diisocyanate (manufactured by Daicel-Hyurus Ltd.), 269 g of methyl isobutyl ketone, 118 g of ethylene glycol monobutyl ether and Dibutyltin dilaurylate (0.2 g) was added, and the mixture was reacted at 70 ° C. under a nitrogen atmosphere until the isocyanate group concentration reached 6.38 mmol / g, and then cyclic lactone ring-opening polyester polyol Praxel 208 (OH equivalent: 409). (Manufactured by Daicel Chemical Industries, Ltd.) 1634 g, and reacted at 70 ° C. under a nitrogen atmosphere until the isocyanate group concentration reached 0.414 mmol / g to obtain a viscous urethane prepolymer solution.

Then, a flask equipped with a stirrer, a thermometer, a nitrogen inlet tube and a reflux condenser was charged with an epoxy equivalent of 19
0 bisphenol A diglycidyl ether 775 g,
Bisphenol A (237 g) and dimethylbenzylamine (13.5 g) were added and reacted at 110 ° C. until the epoxy concentration reached 1.85 mmol / g to obtain an epoxy resin (number average molecular weight 1,025, epoxy equivalent 539).

To this epoxy resin, 1333 g of the above urethane prepolymer solution was added and reacted at 90 ° C. in a nitrogen atmosphere until the isocyanate groups disappeared. Then, dilute with 378 g of ethylene glycol monobutyl ether, add 200 g of diethanolamine, and add 90 ° C.
Then, the reaction is continued until the epoxy group is eliminated, and the solid content is diluted to 75% with ethylene glycol monobutyl ether to obtain a polyurethane-modified amine-added epoxy resin (I-1) having a primary hydroxyl group equivalent of 638 and an amine value of 46.3. It was

2. Production of nonionic acrylic resin Butyl cellosolve 26 parts 80% Polyester monomer ("FM-3X" manufactured by Daicel) 37.5 parts Styrene 40 parts Hydroxyethyl methacrylate 25 parts n-Butyl methacrylate 5 parts AIBN (azobisisobutyro) Nitrile) 4 parts Butyl cellosolve 5 parts Azobisdimethyl valeronitrile 0.5 parts Cellosolve 23 parts The components are heated to 130 ° C.
After dropping over a period of time, maintain at 130 ° C for 2 hours and
The ingredients are added dropwise over 2 hours at 130 ° C.
Hold for time, then add ingredients and cool. Thus, an acrylic resin solution (II-1) having a solid content of 62% and a number average molecular weight of about 5,000 was obtained.

II. Examples and Comparative Examples Resins (I-1) and (II-1) obtained in the above I, 1 and 2 and methyl ethyl ketoxime broccisophorone diisocyanate, which is a cross-linking agent, in the proportions shown in Table 1 (resin solid content). Blended in. Further, 1 g of polypropylene glycol (manufactured by Sanyo Kasei Co., Ltd., Sanniktus PP4000) and formic acid of 0.
82 g and 1 g of lead acetate were added, and deionized water was gradually added with heating to 40 ° C. with stirring to disperse in water to obtain a stable emulsion having a resin solid content of 30%. Thus, 100 g of resin solids of emulsion obtained, 3 g of basic lead silicate, 13 g of titanium white, 0.3 g of carbon, 3 g of clay, 2 g of dibutyltin oxide and nonionic surfactant (trade name: Neugen EA-142B. (Manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) was added, and the pigment was dispersed in a ball mill until the particle size became 10 μm or less, and then diluted with deionized water to a resin solid content of 15%. Resin (I
The compounding ratios of -1) and (II-1) are shown in Table 1.

The cationic electrodeposition coating composition obtained as described above was subjected to cationic electrodeposition coating on a non-treated steel sheet at a bath temperature of 28 ° C. and a voltage of 250 V for 3 minutes. These electrodeposition coated plates were baked at 170 ° C. for 20 minutes to obtain coated panels. Table 1 shows the test results of the coated panels obtained.

[0067]

[Table 1]

The test methods in Table 1 are as follows.

(* 1) Coating state (visual): ◯: good, ×: inferior (* 2) Weather resistance Top clear (Magiclon 700) on the above-mentioned coated panel
0, manufactured by Kansai Paint Co., Ltd.) to obtain a weather resistance test panel. About this test plate, Sunshine weather meter (test temperature: 63 ± 3 ° C., spray cycle: 1 in 60 minutes)
Repeat the test cycle of 2 minutes, humidity 50 ± 5%) 20 hours, 40 ° C. hot water dip 2 hours. After the completion of each cycle, a cross-cut is put on the coated plate and peeled off with a cellophane tape to evaluate the adhesion between the base and the clear. When the peeling of the clear hardly occurred, it was marked with ◯, and when the peeling occurred in a wide range around the cross cut, it was marked with x.
The weather resistance was evaluated as the test time until it became x.

(* 3) Corrosion resistance (against salt spray) A crosscut was put on a coated plate and tested according to JIS Z2871, and after 480 hours, the crosscut was peeled off with cellophane tape and the peeled width was measured.

Claims (1)

[Claims] 1. An I.D. (A) Number average molecular weight is 50 to 8000
A polyurethane compound having one terminal isocyanate group in one molecule obtained by the reaction of the polyhydroxy compound (a), the polyisocyanate compound (b), and the compound (c) having one active hydrogen in one molecule , (B)
A bisphenol type epoxy resin having at least two epoxy groups in one molecule, and (C) a polyurethane-modified amine-added epoxy resin produced by the reaction of an amine compound containing active hydrogen; II. Resin I / Resin II
The cationic electrodeposition coating composition is characterized in that the weight ratio thereof is within the range of 15/85 to 95/5.