JPH05311099A - Electrodeposition coating composition - Google Patents

Abstract

PURPOSE:To provide an electrodeposition coating composition which can give a coating film excellent in corrosion resistance, flexibility, surface smoothness and low-temperature curability by mixing a specified polyamide-modified epoxy- polyamine resin with a specified organotin compound and a bismuth compound or a zirconium compound. CONSTITUTION:The composition comprises a polyamide-modified epoxy- polyamine resin prepared by reacting a phenolic-hydroxyl-terminated polyamide compound comprising a polyamine compound, a polycarboxylic acid and a compound containing a phenolic hydroxyl group and a carboxyl group in the molecule with a bisphenol diglycidyl ether compound and optionally a bisphenol compound and further reacting the obtained product with an amine compound containing active hydrogen atoms, an alkyltin aromatic carboxylate compound of formula I or II (wherein R1 is 1-12C alkyl; and R2 is hydrogen or 1-4C alkyl) and a bismuth compound or a zirconium compound.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electrodeposition coating composition,
Specifically, it relates to an electrodeposition coating composition that can provide a coating film having excellent anticorrosion properties and low temperature curability.

[0002]

2. Description of the Related Art As a resin composition used in a cathodic electrocoating composition, there has been known, for example, JP-A-54-93024.
As disclosed in the publication, a resin composition is generally used in which an epoxy-polyamine resin obtained by reacting an epoxy group-containing resin with a polyamine is combined with a polyisocyanate curing agent blocked with alcohols. As the epoxy group-containing resin, from the viewpoint of anticorrosion property, a bisphenol A diglycidyl ether having a high molecular weight using bisphenol A is usually used, but in order to impart flexibility to the coating film, Further, a plasticizer obtained by introducing a plastic modifier such as a partially soft polyester, polyether, polyamide, polybutadiene, or butadiene-acrylonitrile copolymer into the epoxy resin has been put into practical use. In recent years, in the field of electro-deposition coating of automobile bodies and lower parts, there is an increasing demand for the development of coatings having a high degree of corrosion resistance from the viewpoint of coating film performance. If the amount of the plastic modifier is reduced, corrosion resistance is improved, but there is a problem that flexibility and smoothness of the coated surface are deteriorated.

Further, in order to improve the corrosion resistance of the electrodeposition coating film, a lead compound such as lead acetate or lead chromate is often mixed with the electrodeposition coating material as a rust preventive pigment or as a catalyst. In terms of pollution control, there is a demand for a measure that can achieve equivalent corrosion resistance without using such lead compounds.

Therefore, the present applicants have proposed a resin composition satisfying both corrosion resistance and flexibility in Japanese Patent Application No. 3-348431.
Proposed in the issue. As a result, a resin composition having a high degree of anticorrosion property was obtained, but the baking temperature of the electrodeposition coating using the resin needs to be at least about 150 ° C. as in the case of using the conventional epoxy resin, From the viewpoint of saving energy consumption and the like, there is a demand for an electrodeposition coating composition which is also excellent in low temperature curability.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a specific epoxy-polyamine resin using polyamide as a modifier, a specific organotin compound, and a bismuth compound. Further, the inventors have found that an electrodeposition coating material containing a zirconium compound forms a coating film having excellent corrosion resistance, flexibility, and smoothness of the coating surface, and further has excellent low-temperature curability, and completed the present invention. It was

According to the present invention, however, the number average molecular weight of 40 to 40 having primary and / or secondary amino groups in the molecule is
8,000 polyamine compound (a), number average molecular weight 1
A phenolic hydroxyl group-terminated polyamide compound (A) composed of 00 to 8,000 polycarboxylic acid (b) and a compound (c) having at least one phenolic hydroxyl group and one carboxyl group in one molecule; A polyamide-modified epoxy-polyamine resin obtained by reacting a bisphenol diglycidyl ether compound (B) with a bisphenol compound (C) as the case requires, and further reacting an amine compound (D) having active hydrogen. ,
Alkyl tin ester compound of aromatic carboxylic acid represented by the following formula (I) or (II)

[Chemical 3]

[Chemical 4] (In the formula, R ₁ represents an alkyl group having ₁ to 12 carbons, R ₂ represents a hydrogen atom or an alkyl group having 1 to 4 carbons), a bismuth compound and a zirconium compound. And at least one of the above.

In the present invention, the phenolic hydroxyl group-terminated polyamide compound (A) used in the polyamide-modified epoxy-polyamine resin has a number average molecular weight of 40 to 8,000 having a primary and / or secondary amino group in the molecule. Polyamine compound (a), number average molecular weight 100 to 8,000
0 polycarboxylic acid (b) and at least 1 in one molecule
Composed of a compound (c) having one phenolic hydroxyl group and one carboxyl group, and the constituent ratios of these components are calculated by converting the components (a), (b) and (c) into a total measurement amount. The compound (a) is 5 to 90% by weight, preferably 10 to 60% by weight; the compound (b) is 0 to 80% by weight, preferably 20 to 60% by weight; and the compound (c) is 10% by weight.
It may be in the range of 90 to 90% by weight, preferably 30 to 70% by weight.

The phenolic hydroxyl group-terminated polyamide compound (A) has a number average molecular weight of 400 to 10,000.
0, preferably 1,000 to 4,000, and phenolic hydroxyl group equivalent 100 to 5,000, preferably 400.
It is desirable that it is ˜2,000. Number average molecular weight is 4
When it is less than 00, the flexibility is lowered, while when it exceeds 10,000, the smoothness of the coated surface is lowered, which is not preferable. Further, when the phenolic hydroxyl group equivalent is less than 100, the flexibility is lowered, while when it exceeds 5,000, the coated surface smoothness is lowered, which is not preferable.

Examples of the polyamine compound (a) having a number average molecular weight of 40 to 8,000 and containing two or more primary or secondary amino groups constituting a part of the phenolic hydroxyl group-terminated polyamide compound (A) include piperazine. , Ethylenediamine, ethylaminoethylamine, 1,2-diaminopropane, 1,3-diaminopropane, ethylaminopropylamine, hexamethylenediamine, 2-methylpentamethylenediamine, 2-hydroxyethylaminopropylamine, 1,4-diamino Butane, laurylaminopropylamine, metaxylylenediamine, 1,3-
Bis (aminomethyl) cyclohexane, isophoronediamine, bis (3-aminopropyl) ether, 1,3-
Examples thereof include bis (3-aminopropoxy) -2,2-dimethylpropane, diethylenetriamine, polyoxyalkylenepolyamine and the like. These amino compounds can be used alone or in combination of two or more.

Examples of the compound (b) having two or more carboxyl groups in one molecule which can be used in the production of the phenolic hydroxyl group-terminated polyamide compound (A) include, for example, adipic acid, pimelic acid, suberic acid, azelaic acid and sebacin. Acid, undecanedioic acid, dodecanedioic acid, dimer acid, 1,1-cyclopropanedicarboxylic acid, phthalic acid,
Isophthalic acid, terephthalic acid, 1,2-naphthalenedicarboxylic acid, 2,2'-bibenzyldicarboxylic acid, 4,4
′ -Isopropylidene dibenzoic acid and the like can be mentioned. These carboxylic acid compounds can be used alone or in combination of two or more.

The compound (c) having at least one phenolic hydroxyl group and one carboxyl group in one molecule which can constitute a part of the phenolic hydroxyl group-terminated polyamide compound (A) has a number average molecular weight of 100 to 5, 000, particularly 100 to 2,000, and compounds having the structures shown below can be exemplified.

[0012]

[Chemical 5]

In the formula, R ₃ represents a direct bond or a C _1-20 hydrocarbon group; R ₄ is the same or different and each is C _1-22.
It represents a hydrocarbon group; R ₅ represents a hydrocarbon group of H or C _1-22; n is an integer of from 1 to 10.

Typical of these are hydroxybenzoic acid, hydroxyphenylacetic acid, hydroxyphenylpropionic acid, hydroxyphenylstearic acid and the like.

The phenolic hydroxyl group-terminated polyamide compound (A) is prepared, for example, by mixing (i) the above-mentioned three components (a), (b) and (c) and reacting them, or (ii) in advance. The components (a) and (b) are reacted so that two or more primary and / or secondary amino groups are contained in the molecule to produce a polyamidoamine, and then the polyamidoamine and the component (c) are mixed. Those obtained by reacting can be used.

Of the above-mentioned production methods, the latter method (ii) is preferable, and specifically, the polyamine compound (a) and the polycarboxylic acid (b) are added to the polyamine compound per one amino group of the compound (a). The carboxyl group of the carboxylic acid (b) is mixed in an equivalent ratio or less, preferably in the range of 0.70 to 0.98, and the reaction is carried out to such an extent that it does not substantially have a carboxyl group and has an amino group. A polyamidoamine is produced, and the polyamidoamine and the compound (c) obtained subsequently are used in an amount of equivalent or more, preferably about 1.0 to 1.1, of the carboxyl group of the compound (c) per amino group of the polyamidoamine. It can be produced by blending within the range and carrying out the reaction to such an extent that it has substantially no amino group.

In the present invention, the above-mentioned phenolic hydroxyl group-terminated polyamide compound (A) is reacted with the bisphenol diglycidyl ether compound (B) and the bisphenol compound (C) to obtain a polyamide-modified epoxy resin, which is then further activated. Polyamide-modified epoxy by adding amine compound (D) having hydrogen
A polyamine resin is obtained.

As the reaction for obtaining the polyamide-modified epoxy-polyamine resin, for example, a phenolic hydroxyl group-terminated polyamide compound (A) is reacted with a bisphenol diglycidyl ether compound (B) exceeding the equivalent amount, or necessary. According to the above, the bisphenol compound (C) is reacted with the terminal oxirane group of the resin obtained by the reaction of (A) and (B), and then the amine compound (D) is added to the terminal oxirane group of the obtained polyamide modified epoxy resin.
The addition of the amine compound (D) can be performed simultaneously with the production of the above polyamide-modified epoxy resin, although the addition of the amine compound (D) is particularly preferable in terms of resin design and control.

The bisphenol diglycidyl ether compound (B) used in the above reaction has a number average molecular weight of at least about 310, preferably about 320 to 2,000 and an epoxy resin equivalent of at least about 155, preferably. Bisphenol diglycidyl ether in the range of about 160 to 1,000 is suitable, and in particular, bisphenol A type diglycidyl ether represented by the following formula is particularly preferable in terms of flexibility and corrosion resistance.

[0020]

[Chemical 6]

A typical example of the bisphenol compound (C) is bis (4-hydroxyphenyl) -2,2-.
Propane, bis (4-hydroxyphenyl) -1,1-
Ethane, bis (4-hydroxyphenyl) -methane,
4,4'-dihydroxydiphenyl ether, 4,4 '
-Dihydroxydiphenyl sulfone, bis (4-hydroxyphenyl) -1,1-isobutane, bis (4-hydroxy-3-t-butylphenyl) -2,2-propane and the like.

When a polyamide-modified epoxy resin is produced by reacting a phenolic hydroxyl group-terminated polyamide compound (A), a bisphenol diglycidyl ether type compound (B) and a bisphenol type compound (C), a phenolic hydroxyl group terminated polyamide compound (A ) Is preferably 10% by weight or more based on the total amount of the phenolic hydroxyl group-terminated polyamide compound (A), bisphenol diglycidyl ether compound (B) and bisphenol compound (C). . The amount of the phenolic hydroxyl group-terminated polyamide compound (A) used is 1
If it is less than 0%, it tends to be difficult to obtain a coating film having excellent flexibility and smoothness on the coated surface. Further, it is preferable that the obtained polyamide-modified epoxy resin has a number average molecular weight within the range of 1,000 to 20,000 from the viewpoint of anticorrosion property.

The reaction between the oxirane group and the hydroxyl group to obtain the above polyamide-modified epoxy resin can be carried out by a method known per se, for example, tertiary amines such as triethylamine, tributylamine, dimethylbenzylamine, and trifluoride. In the presence of a catalyst such as a boron fluoride monoethylamine and a boron fluoride compound such as zinc borofluoride, about 40
It can be carried out by heating at a temperature of ℃ to about 200 ℃ for about 1 to 15 hours.

The polyamide-modified epoxy resin obtained as described above can be converted to a polyamide-modified epoxy-polyamine resin by subsequently adding an amine compound (D) having active hydrogen.

The amine compound (D) having active hydrogen includes an oxirane group such as an aliphatic, alicyclic or araliphatic primary or secondary amine, an alkanolamine or a tertiary amine salt. Examples thereof include amine compounds capable of introducing an amino group or a quaternary ammonium salt into a polyamide-modified epoxy resin having active hydrogen capable of reacting. Typical examples of these amine compounds having active hydrogen include the following.

(1) A primary amino group of an amine compound containing one secondary amino group such as diethylenetriamine, hydroxyethylaminoethylamine, ethylaminoethylamine and methylaminopropylamine and one or more primary amino groups. , A compound modified by heating reaction with a ketone, an aldehyde or a carboxylic acid at a temperature of, for example, about 100 to 230 ° C. to give an aldimine, ketimine, oxazoline or imidazoline; (2) diethylamine, diethanolamine, di-n-
Or a second such as -iso-propanolamine, N-methylethanolamine, N-ethylethanolamine
Secondary monoamine; (3) secondary amine-containing compound obtained by adding monoalkanolamine such as monoethanolamine and dialkyl (meth) acrylamide by Michael addition reaction; (4) monoethanolamine, neopentanol A compound obtained by modifying the primary amino group of an alkanolamine such as amine, 2-aminopropanol, 3-aminopropanol, 2-hydroxy-2 '-(aminopropoxy) ethyl ether into ketimine; (5) dimethylethanolamine, triethylamine,
Salts of tertiary amines such as trimethylamine, triisopropylamine and methyldiethanolamine with organic acids such as acetic acid and lactic acid.

The amine compound (D) having these active hydrogens is combined with the oxirane group in the polyamide-modified epoxy resin at a temperature of about 30 to about 160 ° C. for about 1 to about 5, for example.
A polyamide-modified epoxy-polyamine resin can be obtained by reacting for about a time. Further, addition of the amine compound (D) to the polyamide-modified epoxy resin can be performed simultaneously with the production of the epoxy resin, as described above.

The amount of these amine compounds having active hydrogen used is preferably such that the amine value of the polyamide-modified epoxy-polyamine resin of the present invention is within the range of 15 to 100. When the amine value is less than 15, it becomes difficult to disperse the resin in water, and when the amine value exceeds 100,
The resulting coating film tends to have poor water resistance.

The above polyamide-modified epoxy-polyamine 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 control the water dispersibility. It is also possible to improve the smoothness of the coating film. The reaction with these reaction reagents may be carried out before the addition of the amine compound (D) having active hydrogen to the polyurethane-modified epoxy resin.

As the alkyltin ester compound of aromatic carboxylic acid used in the present invention, any aromatic carboxylic acid ester of alkyltin can be used without particular limitation, but the alkyl group of alkyltin has 10 or less carbon atoms. Is preferred, and as the aromatic carboxylic acid, benzoic acid,
Substituted benzoic acid is preferred. Representative examples of the alkyl tin ester compound of an aromatic carboxylic acid include dioctyl tin benzoate oxy, dibutyl tin benzoate oxy, dioctyl tin dibenzoate and dibutyl tin dibenzoate represented by the following formula.

[0031]

[Chemical 7]

[0032]

[Chemical 8]

[0033]

[Chemical 9]

[0034]

[Chemical 10]

In the present invention, examples of the bismuth compound and the zirconium compound used in combination with the above-mentioned alkyl tin ester compound of aromatic carboxylic acid include bismuth hydroxide, bismuth trioxide, bismuth nitrate, bismuth benzoate, bismuth citrate and oxycarbonic acid. Examples thereof include bismuth, bismuth silicate, zirconium dioxide, zirconium silicate, and zirconium hydroxide. Among these, bismuth hydroxide, bismuth silicate, and zirconium hydroxide are particularly preferable. In addition, antimony compounds have some similar effects, and can be used in combination with the bismuth compounds and zirconium compounds.

The total amount of the alkyl tin ester compound of the aromatic carboxylic acid and the bismuth compound and / or the zirconium compound in the present invention can be selected according to the performance required for the electrodeposition coating, but in general, Is 0.1 to 10 relative to 100 parts by weight of the resin solid content of the electrodeposition coating.
It may be in the range of 0.2 to 5 parts by weight, preferably 0.2 to 5 parts by weight.

The mixing ratio of the alkyltin ester compound of an aromatic carboxylic acid and at least one of the bismuth compound and the zirconium compound is within the range of 1:10 to 10: 1 by weight, and any of them may be used alone. The improvement in the curability of the coating film is recognized as compared with the case of using.
Furthermore, if the mixing ratio is within the range of 1: 2 to 2: 1, more preferable results can be obtained.

The polyamide-modified epoxy-polyamine resin can be used in combination with an external cross-linking agent, and a blocked isocyanate group, β-hydroxycarbamic acid ester group, α, β-unsaturated carbonyl group,
Internal crosslinkability can be imparted by introducing a crosslinkable functional group such as an N-methylol group. The introduction of these crosslinkable functional groups may be carried out before adding the amine compound (D) having active hydrogen to the polyamide-modified epoxy resin.

As the external cross-linking agent which can be used in combination, a compound having two or more cross-linking groups in one molecule, for example, blocked polyisocyanate, β-hydroxycarbamic acid ester of polyamine, malonic acid ester derivative, methylolated melamine, Examples thereof include methylolated urea. The compounding ratio (solid content ratio) of the polyamide-modified epoxy-polyamine resin and these external crosslinking agents is 100 /.
The range of 0 to 60/40 is preferable.

Among the above-mentioned external crosslinking agents, blocked polyisocyanates are particularly preferable from the viewpoint of low temperature curability. The blocked polyisocyanates can each be the addition reaction product of a theoretical amount of polyisocyanate compound and an isocyanate blocking agent. Examples of the polyisocyanate compound include aromatic compounds such as tolylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, bis (isocyanatomethyl) cyclohexane, tetramethylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, and isophorone diisocyanate, alicyclic compounds or Ethylene glycol, propylene glycol, trimethylolpropane, hexanetriol, in excess of aliphatic polyisocyanate compounds and these isocyanate compounds,
Examples thereof include a terminal isocyanate-containing compound obtained by reacting a low molecular weight active hydrogen-containing compound such as castor oil.

The above-mentioned isocyanate blocking agent blocks by adding to the isocyanate group of the polyisocyanate compound, and the blocked isocyanate compound formed by the addition is stable at room temperature and about 1
It is desirable that the blocking agent can be dissociated to regenerate a free isocyanate group when heated to 00 to 200 ° C. As a blocking agent satisfying such requirements,
For example, lactam compounds such as ε-caprolactam and γ-butyrolactam; oxime compounds such as methylethylketoxime and cyclohexanone oxime; phenol compounds such as phenol, para-t-butylphenol and cresol; n-butanol, 2-ethylhexanol and the like. Aliphatic alcohols; aromatic alkyl alcohols such as phenylcarbinol and methylphenylcarbinol; ether alcohol compounds such as ethylene glycol monobutyl ether. Of these, oxime-based and phenol-based blocking agents are blocking agents that dissociate at a relatively low temperature, and thus are particularly preferable from the viewpoint of curability of the resin composition for electrodeposition coating.

In the present invention, in the above resin composition,
Although the alkyl tin ester compound of the aromatic carboxylic acid and the bismuth compound or the zirconium compound are contained, the time of mixing them is not particularly limited, but generally, the alkyl tin ester compound is a water-soluble resin for electrodeposition coating resin. It is preferable to add the bismuth compound or the zirconium compound before the formation of the bismuth compound, and it is preferable to pulverize the bismuth compound or the zirconium compound together with other pigments by a ball mill or the like and add the paste to the paint. In many cases, the alkyl tin ester compound is not well compatible when mixed after being made aqueous.

To make the polyamide-modified epoxy-polyamine resin water-soluble or water-dispersible, formic acid,
The amino group may be protonated with a water-soluble organic acid such as acetic acid or lactic acid, and dissolved or dispersed in water. The amount of the acid used for the protonation (neutralization value) cannot be strictly specified, but it is generally about 5 to 40 per 1 g of the resin solid content.
From the viewpoint of electrodeposition characteristics, the number of KOH mg is preferably in the range of 10 to 20 KOH mg. The aqueous solution or aqueous dispersion thus obtained is particularly suitable for cathodic electrodeposition coating.

In the composition of the present invention, if necessary, a coloring pigment such as titanium white or carbon black, an extender pigment such as talc or clay, an anticorrosive pigment such as aluminum phosphomolybdate, a solvent, a pigment dispersant, and an interface. An activator and the like can be added and used.

As the method and apparatus for carrying out electrodeposition coating on an article to be coated using the above aqueous solution or aqueous dispersion, known methods and apparatus conventionally used in cathodic electrodeposition coating can be used. it can. At this time, it is desirable to use the article to be coated as a cathode and 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
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, electrodeposition under stirring condition is desirable.

The coating film deposited on the object to be coated of the cathode can be baked and cured at about 100 ° C. to about 180 ° C. after cleaning.

[0047]

In the electrodeposition coating composition of the present invention, an epoxy resin obtained by using a phenolic hydroxyl group-terminated polyamide compound is composed of a specified component having a polyamide bond in a part of the resin main chain. It is presumed that a coating film excellent in flexibility and appearance can be formed without deteriorating the corrosion resistance of the epoxy resin, because they are bound by the molecular chain. Furthermore, the composition of the present invention contains a bismuth compound and / or a zirconium compound in addition to the alkyl tin ester compound of an aromatic carboxylic acid having good compatibility with the above-mentioned resin, and thus is extremely excellent in low-temperature curability, In the case of the block isocyanate curing type, its effect is large, and also in terms of anticorrosion, it is almost the same as or when it is blended with such a lead compound at a lower baking temperature than that of an ordinary electrodeposition coating containing a lead compound. As described above, it is possible to provide a coating film having excellent rust preventive power.

[0048]

EXAMPLES The present invention will be described in more detail below with reference to examples. In the following, "parts" and "%" mean "parts by weight" and "% by weight", respectively.

Production Example 1 2-Methylpentamethylenediamine 31 was placed in a flask equipped with a stirrer, a thermometer, a nitrogen inlet tube and a reflux condenser.
6 g of dimer acid (acid value 200) and 964 g of xylene 1
After adding 10 g and performing reflux dehydration at 230 ° C. under nitrogen gas blowing, and reacting until the dehydration amount reaches 62 g, 818 g of hydroxyphenylstearic acid (acid value 137)
When the dehydration amount reaches 36 g, xylene is removed under reduced pressure, diluted with 857 g of ethylene glycol monobutyl ether and cooled to obtain a phenolic compound having a solid content of 70% and a phenolic hydroxyl group equivalent of 1,000. A hydroxyl group-terminated polyamide compound (A-1) was obtained.

Next, 1,335 g of bisphenol diglycidyl ether having an epoxy equivalent of 190 and 21 g of diethanolamine were added to 643 g of the above-mentioned phenolic hydroxyl group-terminated polyamide compound A-1, and 21 g of diethanolamine was added, and the epoxy concentration became 3.19 mmol / g at 110 ° C. Then, 521 g of bisphenol A is further added, and the mixture is allowed to react at 110 ° C. until the epoxy group concentration becomes 0.714 mmol / g. Then, the mixture was diluted and cooled with 512.3 g of ethylene glycol monobutyl ether, and when the temperature reached 90 ° C, 173 g of diethanolamine was added, and the mixture was reacted at 90 ° C until the epoxy groups disappeared. Solid content 78%, primary hydroxyl group equivalent 676, amine value 41 A polyamide-modified epoxy-polyamine resin (B-1) solution having 0.5 was obtained.

Production Example 2 1272.6 g of bisphenol A diglycidyl ether having an epoxy equivalent of 190 was placed in the same reactor as in Production Example 1.
Bisphenol A 535.8 g, diethanolamine 2
1 g and 150 g of methyl isobutyl ketone were charged, and 11
React at 0 ° C until the epoxy group concentration becomes 0.909 mmol / g, then dilute and cool with 415 g of ethylene glycol monobutyl ether, and when it reaches 90 ° C, add 173.3 g of diethanolamine and react until the epoxy group disappears. Thus, an epoxy-polyamine resin (B-2) solution having a solid content of 78%, a primary hydroxyl group equivalent of 541 and an amine value of 51.8 was obtained.

Production Example 3 425.3 g of polypropylene glycol diglycidyl ether (epoxy equivalent: 315, manufactured by Tohto Kasei Co., Ltd.), 1222.1 g of bisphenol A diglycidyl ether having an epoxy equivalent of 190, and bisphenol were placed in the same reactor as in Production Example 1. A659.1 g, diethanolamine 21 g
And 150 g of methyl isobutyl ketone were charged, and the temperature was 120 ° C.
To make the epoxy group concentration 0.727 mmol / g, then dilute and cool with 555.2 g of ethylene glycol monobutyl ether, and when it reaches 90 ° C, add 173.3 g of diethanolamine and react until the epoxy group disappears. Thus, a modified epoxy-polyamine resin (B-3) solution having a solid content of 78%, a primary hydroxyl group equivalent of 676, and an amine value of 41.5 was obtained.

Test Example 1 Methyl ethyl ketoxime block isophorone diisocyanate (solid content 23 parts) was added to the resin solution (solid content 77 parts) obtained in Production Example 1. Polypropylene glycol (manufactured by Sanyo Kasei Co., Sannix, PP
4000) 1 g, 1.82 g of acetic acid and 2 g of the solid content of the curing catalyst shown in Table 1 are heated to 40 ° C., and deionized water is added with stirring to disperse the water to obtain a stable clear emulsion having a resin solid content of 20%. Obtained. The curing catalyst used was dispersed as needed.

Using this as an electrodeposition bath and using a degreased steel plate as a cathode, electrodeposition was carried out at 25 ° C. and 190 V for 2 minutes, followed by baking for 30 minutes at the temperature shown in Table 1 to obtain a coating film having a thickness of 10 μm.
Next, Table 1 shows the results of observing the coating film surface after rubbing the baked coating film 10 times with an absorbent cotton containing ethyl cellosolve back and forth. Sample No. 1 to 8 are comparative examples, and 9 to 12 are examples of the present invention. The evaluation was judged according to the following criteria. A solid coating surface that does not cause scratches. ◎ Slight scratches on the coating surface. ○ Countless scratches on the coating surface. △ Part of the coating film peeled off and the bare metal was exposed. × The surface of the coating film is completely peeled off. XX From the results of Table 1, a sample of a combination system of the organotin compound of the present invention and a bismuth compound or a zirconium compound (No. 9 to
12) is electrodeposition coated as compared with samples (Nos. 2 to 5) using a tin catalyst which has been conventionally used and samples (No. 6 to 8) using an organic tin compound used alone in the present invention. It can be seen that the low temperature curability of the film is very excellent.

[0055]

[Table 1]

Examples 1 to 4 and Comparative Examples 1 to 4 Methyl ethyl ketoxime block isophorone diisocyanate was blended in the ratios shown in Table 3 to the three resin solutions obtained in the above Production Examples 1 to 3. To 100 g of the solid content of each of the resin compositions, 1 g of polypropylene glycol (Sanyo Kasei Co., Ltd., Sannix PP4000), a tin compound having the composition shown in Table 3, acetic acid, etc. were added, and the mixture was heated to 40 ° C. with stirring. Deionized water was gradually added and dispersed in water to obtain a clear emulsion for cationic electrodeposition coating having a resin solid content of 35%. 286g of this clear emulsion
69.7 g of the pigment paste having the composition shown in Table 2 below was added with stirring and further diluted with deionized water to a resin solid content of 15% to obtain each electrodeposition coating material shown in Table 3.

[0057]

[Table 2]

Coating Test Each electrodeposition paint obtained as described above was subjected to a bath temperature of 28 ° C.
Untreated steel plate (0.8 × 150 × 7 at voltage 250V for 3 minutes
0 mm) was subjected to cationic electrodeposition coating. These electrodeposition coated plates were baked at 130 ° C. for 20 minutes to obtain coated panels. The obtained coated panel was used as a test plate, and the test results are shown in Table 3.

The test method in Table 3 was carried out as follows.

* 1 Impact resistance (DuPont type) After placing the test plate in a constant temperature and humidity chamber at a temperature of 20 ± 1 ° C. and a humidity of 75 ± 2% for 24 hours, a pedestal of a specified size is placed on the DuPont impact tester. And a 1/2 inch diameter wick, attach the test plate with the coated side facing up, sandwich it between them, then weigh 50
A weight of 0 g was dropped onto the shooting target, and the maximum height (cm) at which there was no crack or peeling of the coating film due to impact was measured.

* 2 Bending resistance After the test plate was placed in a constant temperature and humidity chamber at a temperature of 20 ± 1 ° C. and a humidity of 75 ± 2% for 24 hours, 180 ° bending was performed in 1 to 2 seconds on a bending tester (10 mmφ). Do it. When there is no abnormality on both the front and back sides of the bent part, it is marked as ○, and when there is abnormality such as cracks or peeling on at least one of them, it is ×.
And

* 3 Salt spray resistance A cross-cut was put in a test plate and a salt spray test was conducted according to JIS Z2871. After 840 hours, a cellophane tape was brought into close contact with the cross-cut portion and the peeling width (one side, cm ) Was measured.

* 4 Curability The coated surface of each test plate was covered with four layers of gauze impregnated with methyl isobutyl ketone, and the pressure was about 4 kg / cm ² , and the test surface was about 3 to 3.
The appearance of the coated surface when the length of 4 cm was rubbed 20 reciprocations was visually evaluated. ◯: No scratch is observed on the coated surface. Δ: Scratches are recognized on the coated surface, but the base material is not visible. X: The coating film is dissolved and the substrate is visible.

* 5 Bath stability After stirring the paint for 1 month while keeping it at 30 ° C., 400
Filtration was performed using a mesh wire mesh, and the amount of residue on the wire mesh was evaluated. ◯: Residual amount 0 to less than 10 mg / l Δ: Residual amount 10 mg / l to less than 100 mg / l ×: Residual amount 100 mg / l or more

[0065]

[Table 3]

Claims (2)

[Claims] 1. A polyamine compound (a) having a primary and / or secondary amino group in the molecule and having a number average molecular weight of 40 to 8,000, and a polycarboxylic acid (b) having a number average molecular weight of 100 to 8,000. And a phenolic hydroxyl group-terminated polyamide compound (A) composed of a compound (c) having at least one phenolic hydroxyl group and one carboxyl group in one molecule, and a bisphenol diglycidyl ether compound (B), A polyamide-modified epoxy-polyamine resin obtained by reacting with a bisphenol compound (C) and optionally with an amine compound (D) having active hydrogen, and represented by the following formula (I) or (II): Alkyl tin ester compound of aromatic carboxylic acid [Chemical 2] (In the formula, R ₁ represents an alkyl group having ₁ to 12 carbons, R ₂ represents a hydrogen atom or an alkyl group having 1 to 4 carbons), a bismuth compound and a zirconium compound. And at least one of the above. 2. The electrodeposition coating composition according to claim 1, which contains a blocked polyisocyanate as a crosslinking agent for the polyamide-modified epoxy-polyamine resin.