JPH0848746A - Water-base resin dispersion - Google Patents

Abstract

PURPOSE:To obtain a water-base resin dispersion which is useful as a cationic electrodeposition coating material capable of forming a coating film excellent in weatherability and corrosion resistance. CONSTITUTION:The dispersion contains as the solid component a water-sol. or -dispersible polyurethane-modified epoxy resin/amine adduct which is formed by reacting a polyurethane compd. having one terminal isocyanate group in the molecule, a bisphenol epoxy resin having at least two epoxy groups in the molecule, and an amine compd. having an active hydrogen atom. The polyturethane compd. used is obtd. 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 aqueous resin dispersion, and more specifically, an aqueous resin dispersion capable of forming a coating film excellent in weather resistance and anticorrosion property, particularly suitable for cathodic electrocoating. Regarding liquid.

[0002]

2. Description of the Related Art As an aqueous resin dispersion for a cathodic electrocoating composition, a block polyisocyanate compound is conventionally blended as a curing agent with an amine-added epoxy resin obtained by a reaction between an epoxy resin and an active hydrogen-containing amino compound. The composition 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 aqueous resin composition capable of forming a coating film excellent in both corrosion resistance and weather resistance, and as a result, modified epoxy resin. Therefore, they have found that the above object can be achieved by using a specific polyurethane resin, and have completed the present invention.

According to the present invention, however, (A) a polyhydroxy compound (a) having a number average molecular weight of 50 to 8000, a polyisocyanate compound (b), and a compound having one active hydrogen atom in one molecule. Polyurethane compound having one terminal isocyanate group in one molecule obtained by the reaction of (c), (B) Bisphenol type epoxy resin having at least two epoxy groups in one molecule, and (C) Active hydrogen There is provided an aqueous resin dispersion liquid comprising a water-solubilized or water-dispersed product of a polyurethane-modified amine-added epoxy resin produced by a reaction of an amine compound containing a.

The aqueous resin dispersion of the present invention will be described in more detail below.

Polyurethane compound (A): The polyurethane compound (A) is obtained by the reaction of a polysidoxy compound (a), a polyisocyanate compound (b) and a compound (c) having one active hydrogen in one molecule. It is a polyurethane compound having one terminal isocyanate group in the molecule, and it is generally desirable that it has a number average molecular weight in the range of 400 to 10,000, preferably 1,000 to 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 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). The baking temperature of the coating film of the aqueous resin dispersion formed (usually 120 to 200 ° C., preferably 160
It is possible to use a compound which dissociates from a blocked isocyanate group at ˜180 ° C.) to give a free isocyanate group.

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 to 80% by weight, polyisocyanate compound (b): 5 to 80% by weight, preferably 10 to 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 preferable, 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 smoothness of the coated surface is lowered, which is not preferable.

Bisphenol-type epoxy resin (B): The bisphenol-type epoxy resin (B) is a bisphenol-based compound having at least two epoxy groups in one molecule, and in particular, a bisphenol-based 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, the bisphenol A type diglycidyl ether represented by the following formula is a flexible resin,
It is particularly suitable in that it gives a coating film having excellent anticorrosion properties.

[0025]

Embedded image

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

As an epoxy resin (B), an excess amount of bisphenol diglycidyl ether 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 which is the main component of the aqueous resin dispersion of the present invention is, for example, a polyurethane-modified epoxy resin obtained by reacting the above-mentioned polyurethane compound (A) with a bisphenol type epoxy resin (B). After obtaining, further active hydrogen-containing amine compound (C)
Can be obtained by adding.

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 ratios of the respective components of the polyurethane compound (A), the epoxy resin (B) and the active hydrogen-containing amino compound (C) can be varied over a wide range depending on 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 preferably has a number average molecular weight in the range of usually 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 the range of the primary hydroxyl group equivalent is not particularly limited, but is usually 600 to 1,000, and 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 reaction with the above-mentioned 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.

The polyurethane-modified amine-added epoxy resin obtained as described above can be used in combination with an external crosslinking agent. The external cross-linking agent that can be used in combination is a compound having two or more cross-linkable functional groups in one molecule, for example, block polyisocyanate, polyamine β-hydroxycarbamic acid ester, malonic acid ester, malonic acid ester derivative, and methylolated melamine. , Methylolated urea and the like. The compounding ratio (solid content ratio) of the polyurethane-modified amine-added epoxy resin and these external crosslinking agents is not strictly limited, but is usually 100 /
It is preferably in the range of 0 to 60/40, particularly 85/15 to 60/40.

The polyurethane-modified amine-added epoxy resin can be water-solubilized or water-dispersed by protonating the amino group in the resin with a water-soluble organic acid such as formic acid, acetic acid, lactic acid. The amount of the acid that can be used for the above protonation (neutralization value) depends on the type of the resin and cannot be strictly defined, but in general, about 5 to about 40 KOHmg per 1 g of the resin solid content, particularly 1
The range of 0 to 20 KOHmg is preferable in terms of electrodeposition characteristics.

The water-solubilized or water-dispersed product of the polyurethane-modified amine-added epoxy resin thus obtained can be dissolved or dispersed in an aqueous medium to give the aqueous resin dispersion of the present invention. The concentration of the polyurethane-modified amine-added epoxy resin in the dispersion is not particularly limited and can be varied over a wide range depending on the application of the dispersion and the like, but is generally 32 to 36% by weight in terms of solid content, particularly A range of 35 to 36% by weight is suitable.

The aqueous resin dispersion of the present invention is particularly suitable for use in a cathodic electrocoating composition. In this case, a pigment, a solvent, a curing catalyst, a surfactant, etc. may be added, if necessary. it can.

As the method and apparatus for performing electrodeposition coating on an article to be coated using the aqueous resin dispersion of the present invention, known methods and apparatuses conventionally used in cathodic electrodeposition coating can be used. You can 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 generally bath temperature: 20 to 30
C, voltage: 100 to 400 V (preferably 200 to 30)
0 V), current density: 0.01 to 3 A / dm ² , energization time:
1 to 5 minutes, electrode area ratio (A / C): 2/1 to 1/2, distance between electrodes: 10 to 100 cm, and electrodeposition in a stirred state is desirable.

After washing, the coating film deposited on the object to be coated on the cathode can be baked and cured at a temperature of about 140 ° C. to about 180 ° C.

[0046]

FUNCTION AND EFFECT Since the polyurethane-modified amine-added epoxy resin in the aqueous resin dispersion of the present invention is modified with a specific polyurethane compound, the polyurethane-modified amine in the coating film formed by using the aqueous resin dispersion is modified. Good compatibility between epoxy resin and unmodified epoxy resin,
Therefore, by using the aqueous resin dispersion of the present invention, it is possible to form a coating film having excellent weather resistance, corrosion resistance and appearance.

[0047]

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

Production Example 1 Production of Polyurethane Compound In a flask equipped with a stirrer, a thermometer, a nitrogen introducing tube and a reflux condenser, 666 g of isophorone diisocyanate (manufactured by Daicel-Hyurus Co., Ltd.), 269 g of methyl isobutyl ketone, and ethylene glycol monobutyl ether. 118 g and dibutyltin dilaurylate 0.2 g were added and reacted at 70 ° C. under a nitrogen atmosphere until the isocyanate group concentration reached 6.38 mmol / g, and then the cyclic lactone ring-opening polyester polyol Praxel 208 (OH equivalent weight). : 409, manufactured by Daicel Chemical Industries, Ltd.) 1634 g, and reacted at 70 ° C. under a nitrogen atmosphere until the isocyanate group concentration became 0.414 mmol / g to obtain a viscous urethane prepolymer solution.

Polyurethane-modified amine-added epoxy
Production of resin In a flask equipped with a stirrer, a thermometer, a nitrogen introduction tube and a reflux condenser, 775 g of bisphenol A diglycidyl ether having an epoxy equivalent of 190 and bisphenol A2
Add 37 g and 13.5 g of dimethylbenzylamine,
Epoxy resin (number average molecular weight 1.02) was reacted at 110 ° C until the epoxy concentration reached 1.85 mmol / g.
5, epoxy equivalent 539) was obtained.

To this epoxy resin, 1333 g of the urethane prepolymer solution prepared in was added and reacted at 90 ° C. in a nitrogen atmosphere until the isocyanate groups were exhausted. Then ethylene glycol monobutyl ether 3
Dilute with 78 g, add 200 g of diethanolamine,
The reaction is carried out at 90 ° C. until the epoxy group disappears, and the solid content is diluted to 75% with ethylene glycol monobutyl ether to obtain a polyurethane-modified amine-added epoxy resin (1) having a primary hydroxyl equivalent of 638 and an amine value of 46.3. It was

Production Example 2 Production of Polyurethane Resin In a flask equipped with a stirrer, a thermometer, a nitrogen introducing tube and a reflux condenser, 837 g of isophorone diisocyanate (manufactured by Daicel-Hyurus Co., Ltd.), 267 g of methyl isobutyl ketone, and 1 part of ethylene glycol monobutyl ether.
18 g and dibutyl tin dilaurate 0.2 g were added,
At 70 ° C, the isocyanate group concentration is 2.90 mmol /
reaction under a nitrogen atmosphere until the product reaches g, and then Praxel 2 which is a cyclic lactone ring-opening polyester polyol.
05 (OH equivalent: 409, manufactured by Daicel Chemical Industries, Ltd.) 1445 g was added and reacted at 70 ° C. under a nitrogen atmosphere until the isocyanate group concentration became 0.417 mmol / g, and a viscous urethane prepolymer solution was added. Got

Polyurethane-modified amine-added epoxy
Production of resin In a flask equipped with a stirrer, a thermometer, a nitrogen introduction tube and a reflux condenser, 775 g of bisphenol A diglycidyl ether having an epoxy equivalent of 190 and bisphenol A2
Add 37 g and 13.5 g of dimethylbenzylamine,
Epoxy resin (number average molecular weight 1.02) was reacted at 110 ° C until the epoxy concentration reached 1.85 mmol / g.
5, epoxy equivalent 539) was obtained.

To this epoxy resin, 1333 g of the urethane prepolymer solution prepared in was added and reacted at 90 ° C. under a nitrogen atmosphere until the isocyanate groups were exhausted. Then ethylene glycol monobutyl ether 3
Dilute with 78 g, add 200 g of diethanolamine,
The reaction is carried out at 90 ° C. until the epoxy group disappears, and the solid content is diluted to 75% with ethylene glycol monobutyl ether to obtain a polyurethane-modified amine-added epoxy resin (2) having a primary hydroxyl equivalent of 638 and an amine value of 46.3. It was

Production Example 3 (Comparative Example) In a flask equipped with a stirrer, a thermometer, a nitrogen introducing tube and a reflux condenser, 775 g of bisphenol A diglycidyl ether having an epoxy equivalent of 190 and bisphenol A2 were used.
Add 37 g and 13.5 g of dimethylbenzylamine,
Epoxy resin (number average molecular weight 1.02) was reacted at 110 ° C until the epoxy concentration reached 1.85 mmol / g.
5, epoxy equivalent 539) was obtained.

This epoxy resin was mixed with ε-caprolactone 1
200 g and 0.21 g of tetrabutyl orthotitanate are added and reacted at 170 ° C. until the heating residue reaches 100%. Then, dilute with 378 g of ethylene glycol monobutyl ether, add 200 g of diethanolamine, and react at 90 ° C. until the epoxy group disappears, dilute to 75% solid content with ethylene glycol monobutyl ether, primary hydroxyl group equivalent 505, amine value An ε-caprolactone-modified amine-added epoxy resin having 46.3 was obtained.

Examples 1 and 2 and Comparative Example 1 Methyl ethyl ketoxime block isophorone diisocyanate was added to the resins obtained in the above Production Examples 1 to 3, and the block isocyanate group was a polyurethane and ε-caprolactone modified epoxy-polyamine resin. It was blended so as to be equivalent to the primary hydroxyl group. 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%.

The three kinds of diluted paints obtained as described above were 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. 170 ° C for these electrodeposition coated plates
After baking for 20 minutes, a coated panel was obtained. Table 1 shows the test results of the coated panels obtained.

The test methods in Table 1 are as follows.

(* 1) Weather resistance Top clear (Magiclon 700
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.

(* 2) Corrosion resistance (against salt spray) A crosscut was put in 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.

[0061]

[Table 1]

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Claims (1)

[Claims] (A) Obtained by reacting a polyhydroxy compound (a) having a number average molecular weight of 50 to 8000, a polyisocyanate compound (b), and a compound (c) having one active hydrogen in one molecule. Compound having one terminal isocyanate group in one molecule, (B)
A bisphenol type epoxy resin having at least two epoxy groups in one molecule and (C) a water-solubilized or water-dispersed product of a polyurethane-modified amine-added epoxy resin produced by the reaction of an amine compound containing active hydrogen (C) An aqueous resin dispersion, which is characterized by containing as.