JPH06100806A - Electrodeposition coating composition - Google Patents

Abstract

PURPOSE:To obtain the subject compsn. which gives a coating film excellent in corrosionproofness, flexibility, and low-temp. curability by compounding a specific polyurethane-modified epoxy-polyamine resin, an alkyltin ester of an arom. carboxylic acid, and a lanthanum compd. CONSTITUTION:An epoxidized polyurethane obtd. from a polyhydroxyl compd. having a number-average mol.wt. of 50-8,000, a polyisocyanate, and a compd. having at least one hydroxyl group and at least one alicyclic epoxy group in the molecule is reacted with a bisphenol compd., a bisphenol diglycidyl ether, and an amine compd. having an active hydrogen atom to give a polyurethane- modified epoxy-polyamine resin. The objective compsn. contains this resin, at least one alkyltin ester of an arom. carboxylic acid selected from the group consisting of compds. of formulae I and II (wherein R1 is 1-12C alkyl; and R2 is H or 1-4C alkyl), and at least one lanthanum compd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrodeposition coating composition, and more particularly to an electrodeposition coating composition capable of providing a coating film excellent in corrosion resistance and low temperature curability.

[0002]

2. Description of the Related Art As a resin composition used in a cathodic electrodeposition coating 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 polymer obtained by polymerizing bisphenol A diglycidyl ether with bisphenol A is usually used, but in order to impart flexibility to the coating film, Furthermore, 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 blended in 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 anticorrosion property and flexibility in Japanese Patent Application No. 3-348372.
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 must 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 which is 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 with polyurethane as a modifier, a specific organotin compound, and a lanthanum compound are used. The present inventors have found that the electrodeposition coating composition containing the composition forms a coating film having excellent anticorrosion properties, flexibility, and smoothness of the coating surface, and is also excellent in low-temperature curability, and completed the present invention.

According to the present invention, however, a polyhydroxy compound (a) having a number average molecular weight of 50 to 8,000, a polyisocyanate compound (b), and one hydroxyl group and at least one alicyclic ring in one molecule. An epoxy group-containing polyurethane compound (A) composed of a compound (c) having a formula epoxy group, a bisphenol compound (B), a bisphenol diglycidyl ether compound (C), and an amine compound (D) having active hydrogen. ) Polyurethane-modified epoxy-polyamine-based resin comprising a reaction product with an alkylcarboxylic acid ester of an aromatic carboxylic acid represented by the following formulas (I) and (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), and at least one of lanthanum compounds. An electrodeposition coating composition is provided which comprises a seed.

In the present invention, the epoxy group-containing polyurethane compound (A) used in the polyurethane-modified epoxy-polyamine resin is a polyhydroxy compound (a), a polyisocyanate compound (b) and 1 having a number average molecular weight of 50 to 8,000. It is composed of a compound (c) having one hydroxyl group and at least one alicyclic epoxy group in the molecule, and the composition ratios of these components are the components (a), (b) and ( The compound (a) is 5 to 80% by weight, preferably 20 to 60% by weight, and the compound (b) is 5 to 90% by weight, preferably 10 in terms of the total measurement of c).
60% by weight; Compound (c) may be in the range of 10 to 90% by weight, preferably 30 to 70% by weight.

The epoxy group-containing polyurethane compound (A) has a number average molecular weight of 400 to 10,000, preferably 1,000 to 4,000, and an epoxy equivalent of 10.
It is desired to be 0 to 5,000, preferably 400 to 2,000. When the number average molecular weight is less than 400, flexibility tends to decrease, while when it exceeds 10,000, the smoothness of the coated surface tends to decrease. Also, the epoxy equivalent is 10
When it is less than 0, the flexibility is lowered, while when it is more than 5,000, the smoothness of the coated surface tends to be lowered.

Epoxy group-containing polyurethane compound (A)
As the polyhydroxy compound (a) having a number average molecular weight of 50 to 8,000 which can form a part of the above, any polyhydroxy compound (a) can be used without particular limitation as long as it satisfies the above conditions. Examples include various polyester polyols or polyether polyols used in the production of alcohols and general urethane compounds, and mixtures thereof. Examples of the polyester polyol as used herein include condensates of polyhydric alcohols and polybasic carboxylic acids, condensates of hydroxycarboxylic acids and polyhydric alcohols, and those obtained by ring-opening of cyclic lactones.

Examples of the polyhydric alcohol used for producing the above polyhydric alcohol and polyester polyol or polyether polyol include ethylene glycol, propylene glycol, butanediol, diethylene glycol, 3-methyl-1,5-pentanediol and glycerin. , 1,6-hexanediol, trimethylolpropane and the like, and examples of the polybasic carboxylic acid used in the production of the polyester polyol include adipic acid, azelaic acid, dimer acid, glutaric acid and pyromellitic acid. Can be mentioned. As the condensate of hydroxycarboxylic acid and polyhydric alcohol, castor oil, castor oil and reaction products of ethylene glycol, propylene glycol and the like can also be used.

The polyether polyol is, for example, one of alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide and tetrahydrofuran.
It is a product obtained by addition-condensing one kind or two or more kinds to a compound having two or more active hydrogens, and any known polyether polyol used for producing a usual polyurethane resin can be used. In this case, examples of the compound having two or more active hydrogens include the above-mentioned polyhydric alcohols and polybasic carboxylic acids, amines such as ethylenediamine and hexamethylenediamine; alkanolamines such as ethanolamine and propanolamine. Polyphenols such as bisphenols; castor oil and the like.

The above polyhydroxy compound (a) has a number average molecular weight of 50 to 50 containing an average of two or more hydroxyl groups in one molecule.
8,000, preferably 50 to 6,000, and when the average number of the hydroxyl groups is less than 2 in one molecule, the molecular weight of the polyurethane compound is low, so that the corrosion resistance and flexibility of the coating film deteriorate. Further, when the number average molecular weight is more than 8,000, the solution viscosity of the resin becomes high, which makes handling difficult and the compatibility with other resins deteriorates, which is not preferable.

The polyhydroxy compound (a) having a number average molecular weight of 50 to 8,000 can be used alone,
Alternatively, it can be used as a mixture of a low molecular weight polyhydroxy compound having a number average molecular weight of 50 to 499 and a high molecular weight polyhydroxy compound having a number average molecular weight of 500 to 8,000.

As the low molecular weight polyhydroxy compound, for example, the polyhydric alcohol component described above or the polyester polyol or polyether polyol shown above having a number average molecular weight of 499 or less can be used.

As the high molecular weight polyhydroxy compound, for example, the number average molecular weight of the polyester polyol or polyether polyol shown above is 500.
~ 8,000 are used.

The blending ratio of the high molecular weight polyhydroxy compound and the low molecular weight polyhydroxy compound is not particularly limited and can be used in any blend depending on the required performance, but is preferably low relative to 100 parts by weight of the high molecular weight polyhydroxy compound. The molecular weight polyhydroxy compound is in the range of about 5 to 70 parts by weight.

Epoxy group-containing polyurethane compound (A)
The polyisocyanate compound (b) that can be used for the production of the above is a compound having two or more isocyanate groups in the molecule, and various compounds used in the production of general polyurethane resins can be used. Examples of the compound (b) include aliphatic, alicyclic, and araliphatic polyisocyanate compounds, and the following can be typically exemplified.

Aliphatic polyisocyanate compound: hexamethylene diisocyanate (HMDI), HMDI buret compound, HMDI isocyanurate compound and the like.

Alicyclic polyisocyanate compound: isophorone diisocyanate (IPDI), burette compound of IPDI, isocyanurate compound of IPDI,
Hydrogenated xylylene diisocyanate, hydrogenated 4,4
′ -Diphenylmethane diisocyanate and the like.

Aroaliphatic polyisocyanate compound:
Xylylene diisocyanate, meta (or para) tetramethylene diisocyanate, etc.

These may be used alone or in combination of two or more.

Epoxy group-containing polyurethane compound (A)
The compound (c) having one hydroxyl group and at least one alicyclic epoxy group in the molecule that can form a part of is an alicyclic structure composed of 5 to 6 carbon atoms (carbon-carbon double bond). Epoxy group (oxirane group) is directly bonded to the compound (not having a group). Such compounds include number average molecular weights of 100 to 5,0.
00, especially about 100 to 2,000, epoxy equivalent of about 10
0-1,000, especially about 120-600, melting point about 130
C. or less, particularly about 50 to 115.degree. C. can be preferably used, and compounds having the structures shown below can be exemplified.

[0023]

[Chemical 5]

The formula, R ₃ represents a divalent hydrocarbon group direct bond or C ₁ ~ _20; R ₄ are identical or different,
Each represent a divalent hydrocarbon group of C ₁ ~ _8; R ₅ is H,
It represents CH _3; n is an integer of from 1 to 10.

The divalent hydrocarbon group may be any of saturated aliphatic, aromatic, alicyclic, and combinations thereof. The saturated aliphatic may be linear or branched. Further, the aromatic includes an aromatic ring substituted with an alkyl group or the like. As these preferred embodiments, methylene divalent hydrocarbon group of C ₁ ~ _8, ethylene, propylene,
2-methylpropylene, hexamethylene, phenylene,

[0026]

[Chemical 6]

[0027] include groups such as, also, 2 of C ₁ ~ ₂₀
The valent hydrocarbon group other than a divalent hydrocarbon group of C ₁ ~ _8, decamethylene and octadecamethylene the like.

Among these, the following can be exemplified as those commercially available.

[0029]

[Chemical 7]

Epoxy group-containing polyurethane compound (A)
(I) For example, the three components (a) described above,
(B) and (c) are blended and reacted, or (ii)
Preliminary two components (a) and (b) are reacted so that two or more isocyanate groups are contained in the molecule to produce a urethane prepolymer, and then the urethane prepolymer and the component (c) are reacted. What is obtained by making it can be used.

Of the above-mentioned production methods, the latter method (ii) is preferable, and specifically, the polyisocyanate compound (b) and the polyhydroxy compound (a) are combined with the compound (b).
Per 1 isocyanate group, the hydroxyl group of the compound (a) is blended in a ratio of not more than the equivalent, preferably in the range of 0.70 to 0.98, and the reaction is carried out to the extent that it has substantially no hydroxyl group. A urethane prepolymer containing the compound (c) is produced, and then the resulting urethane prepolymer and the compound (c) are added to the isocyanate group 1 of the urethane prepolymer.
It is produced by blending the hydroxyl groups of the compound (c) in an equivalent amount or more, preferably in the range of about 1.0 to 1.1, and reacting to a degree not having substantially isocyanate groups. be able to.

In the reaction between the above isocyanate group and hydroxyl group, if necessary, a known catalyst for urethane synthesis, such as a tertiary amine, (eg: triethylamine), an organometallic compound (eg: dibutyltin) is used. Dilaurate) can be added.

The epoxy group-containing polyurethane compound (A) shown above is reacted with the bisphenol compound (B) and the bisphenol diglycidyl ether compound (C) to obtain a polyurethane-modified epoxy resin.
Further, a polyurethane-modified epoxy-polyamine resin is obtained by adding an amine compound (D) having active hydrogen.

The reaction for obtaining the polyurethane-modified epoxy-polyamine resin is, for example, the reaction of the epoxy group-containing polyurethane compound (A) with the bisphenol compound (B) in excess of the equivalent amount to obtain a terminal hydroxyl group of the resin obtained. A method of reacting an equivalent amount of a bisphenol diglycidyl ether compound (C) and then adding an amine compound (D) to the terminal oxirane group of the resulting polyurethane-modified epoxy resin is particularly preferable in terms of resin design and control. However, the addition of the amine compound (D) can be carried out simultaneously with the production of the above polyurethane-modified epoxy resin.

A typical example of the bisphenol compound (B) used in the above reaction 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.

The bisphenol diglycidyl ether compound (C) has a number average molecular weight of at least about 310, preferably in the range of about 320 to 2,000 and an epoxy equivalent of at least about 155, preferably about 160. ~
Bisphenol diglycidyl ether in the range of 1,000 is suitable, especially the following formula

[0037]

[Chemical 8]

The bisphenol A type diglycidyl ether represented by is particularly preferable in terms of flexibility and corrosion resistance.

When the epoxy group-containing polyurethane compound (A), the bisphenol compound (B) and the bisphenol diglycidyl ether (C) are reacted to produce an epoxy resin, the amount of the epoxy group-containing polyurethane compound (A) used is It is preferably 10% by weight or more based on the total amount of the epoxy group-containing polyurethane compound (A), bisphenol (B) and bisphenol diglycidyl ether (C). If the amount of the epoxy group-containing polyurethane compound (A) used is less than 10%, it tends to be difficult to obtain a coating film having excellent flexibility and smoothness of the coated surface.

The polyurethane-modified epoxy resin obtained preferably has a number average molecular weight within the range of 1,000 to 20,000 from the viewpoint of anticorrosion properties.

The reaction between the oxirane group and the hydroxyl group to obtain the polyurethane-modified epoxy resin can be carried out by a method known per se, for example, triethylamine,
In the presence of a catalyst such as tertiary amines such as tributylamine and dimethylbenzylamine, boron trifluoride monoethylamine, and boron fluoride compounds such as zinc borofluoride, about 4
It can be carried out by heating at a temperature of 0 ° C. to about 200 ° C. for about 1 to 15 hours.

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

As the amine compound (D) having active hydrogen, an oxirane group such as an aliphatic, alicyclic or araliphatic primary or secondary amine, an alkanolamine or a tertiary amine salt is used. Examples thereof include amine compounds capable of introducing an amino group or a quaternary ammonium salt into the polyurethane-modified epoxy resin having reactive hydrogen that can react. The following can be mentioned as typical examples of these amine compounds having active hydrogen.

(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 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 reacted with the oxirane group in the polyurethane-modified epoxy resin at a temperature of, for example, about 30 to about 160 ° C. for about 1 to about 5 hours to produce a polyurethane-modified epoxy resin. -A polyamine resin can be obtained. Also,
As described above, the addition of the amine compound (D) to the polyurethane-modified epoxy resin can be performed simultaneously with the production of the polyurethane-modified epoxy resin.

The amount of these amine compounds (D) having active hydrogen used is preferably such that the amine value of the polyurethane-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 water resistance of the resulting coating film tends to be poor.

The above polyurethane-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. Are 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.

[0049]

[Chemical 9]

[Chemical 10]

[Chemical 11]

[Chemical 12]

The amount of the above-mentioned dialkyltin aromatic carboxylic acid salt to be used can be selected according to the performance required for the electrodeposition coating composition, but in general, the resin solid content in the electrodeposition coating composition is 100% by weight. The amount is 0.1 to 10 parts by weight, preferably 0.2 to 5 parts by weight. If it is out of this range, the low temperature curability or the bath stability tends to be adversely affected.

The lanthanum compound used in combination with the above-mentioned alkyl tin ester compound of aromatic carboxylic acid in the present invention is an organic or inorganic water-soluble or sparingly water-insoluble compound containing lanthanum as a constituent component, Examples thereof include lanthanum organic acid salts such as lanthanum acetate, lanthanum lactate, and lanthanum oxalate, and inorganic lanthanum compounds such as lanthanum nitrate, lanthanum hydroxide, lanthanum oxide, and lanthanum tungstate. Of these, water-soluble lanthanum compounds such as organic acid salts are advantageous because they dissolve in a bath and can be effective even when used in a small amount. Lanthanum acetate is particularly preferable.

The compounding amounts (total) of the alkyl tin ester compound of an aromatic carboxylic acid and the lanthanum compound in the present invention can be selected according to the performance required for the electrodeposition coating, but generally, 0.1 to 10 parts by weight, preferably 0.2 to 10 parts by weight of resin solids
It can be in the range of 5 parts by weight.

The mixing ratio of the alkyl tin ester compound of aromatic carboxylic acid and the lanthanum compound is 1:10 by weight.
Within the range of 10: 1, improvement in the curability of the coating film is recognized at any rate compared to the case of using each alone. Further preferable results can be obtained if the mixing ratio is within the range of 1: 2 to 2: 1.

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

The external cross-linking agent is a compound having two or more cross-linking groups in one molecule, for example, blocked polyisocyanate, polyamine β-hydroxycarbamic acid ester, malonic acid ester derivative, methylolated melamine, methylolated urea. And so on. The compounding ratio (solid content ratio) of the polyurethane-modified epoxy-polyamine resin and these external crosslinking agents is 100/0 to 6
It is preferably within the range of 0/40.

Among the above-mentioned external crosslinking agents, blocked polyisocyanates are particularly preferable from the viewpoint of low temperature curability. The blocked polyisocyanate compound can be the addition reaction product of each theoretical amount of the polyisocyanate compound and the 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 Terminal polyisocyanate compounds obtained by reacting an aliphatic polyisocyanate compound and an excess amount of these isocyanate compounds with a low-molecular-weight active hydrogen-containing compound such as ethylene glycol, propylene glycol, trimethylolpropane, hexanetriol, and castor oil. To be

On the other hand, the isocyanate blocking agent is one which blocks by adding to the isocyanate group of the polyisocyanate compound, and the blocked isocyanate compound produced by the addition is stable at room temperature and when heated to about 100 to 200 ° C. It is desirable that the blocking agent can be dissociated to regenerate a free isocyanate group. Examples of the blocking agent satisfying such requirements are lactam compounds such as ε-caprolactam and γ-butyrolactam; methylethylketoxime,
Oxime-based compounds such as cyclohexanone oxime; phenol-based compounds such as phenol, para-t-butylphenol and cresol; aliphatic alcohols such as n-butanol and 2-ethylhexanol; aromatics such as phenylcarbinol and methylphenylcarbinol Alkyl alcohols; ether alcohol compounds such as ethylene glycol monobutyl ether and the like can be mentioned. Of these, the oxime-based and phenol-based blocking agents are blocking agents that dissociate at a relatively low temperature, and thus are particularly suitable 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 and the lanthanum compound of the aromatic carboxylic acid are contained, the time of mixing them is not particularly limited. Generally, the alkyl tin ester compound is added before water-solubilizing the resin for electrodeposition coating composition. Is preferably added to. In many cases, the alkyl tin ester compound is not well compatible when mixed after being made aqueous. Further, the introduction of the lanthanum compound into the electrodeposition coating composition is not particularly limited and can be carried out in the same manner as an ordinary pigment dispersion method. For example, the lanthanum compound is previously dispersed in a dispersing resin. A dispersion paste can be prepared by adding the dispersion paste, or in the case of a water-soluble lanthanum compound, the dispersion paste can be added as it is after the preparation of the resin emulsion for the coating material. Examples of preferable cationic resins as the dispersing resin include epoxy type tertiary amine type resins, acrylic type quaternary ammonium salt type resins, and epoxy type quaternary ammonium salt type resins.

The dispersion paste can be prepared from the above lanthanum compound and the dispersing resin in the same manner as in the case of blending pigments into an ordinary electrodeposition coating composition. Specifically, for example, lanthanum is used. It can be carried out by dispersing the compound together with the above-mentioned dispersing resin and the like in a dispersion mixer such as a ball mill to form a paste. At that time, other pigments and the like may be dispersed together with the lanthanum compound.

Other pigments that can be used are not particularly limited as long as they are pigments usually used in electrodeposition paints, and any pigments can be used. For example, coloring pigments such as titanium oxide, carbon black, red iron oxide, and the like; Extender pigments such as clay, mica, barita, talc, calcium carbonate, silica;
Examples include rust preventive pigments such as aluminum phosphomolybdate and aluminum tripolyphosphate.

In order to make the above polyurethane-modified epoxy-polyamine resin water-soluble or water-dispersible, the amino group is protonated with a water-soluble organic acid such as formic acid, acetic acid or lactic acid to dissolve or disperse it in water. You can do it.

The amount of acid used for protonation (neutralization value) cannot be strictly specified, but generally 1 g of resin solids
Therefore, the range of about 5 to 40 KOHmg, especially 10 to 20 KOHmg is preferable in view of electrodeposition characteristics. The aqueous solution or aqueous dispersion thus obtained is particularly suitable for cathodic electrodeposition coating, and in this case, if necessary, a coloring pigment, an extender pigment,
A rust preventive pigment, a solvent, a pigment dispersant, a surfactant and the like can be added and used.

As the method and apparatus for carrying out electrodeposition coating on an object 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 object 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 cathode article to be coated can be baked and cured at about 100 ° C. to about 180 ° C. after cleaning.

[0065]

The electrodeposition coating composition of the present invention uses an epoxy-polyamine resin modified with an epoxy group-containing polyurethane compound so that the main skeleton of the epoxy group-containing polyurethane is a polyhydroxy compound and a polyhydroxy compound. It is composed of polyurethane bonds by reaction with an isocyanate compound, and the alicyclic structure is introduced into the resin by the alicyclic epoxy group at the end of the epoxy group-containing polyurethane compound, which reduces the corrosion resistance of the epoxy resin. It is presumed that a coating film excellent in flexibility and appearance can be formed without doing so. Furthermore, the composition of the present invention contains a lanthanum compound in addition to the alkyl tin ester compound of an aromatic carboxylic acid having good compatibility with the above-mentioned resin, so that it is extremely excellent in low-temperature curability, particularly of a blocked isocyanate curing type. In this case, the effect is large, and it is possible to provide a coating film having an anticorrosion property which is almost equal to or even better than the case where a lead compound or the like is added.

[0066]

EXAMPLES The present invention will be described in more detail below with reference to examples. In addition, "%" means "weight%" below.

Production Example 1 In a flask equipped with a stirrer, a thermometer, a nitrogen inlet tube and a reflux condenser, polytetramethylene glycol (hydroxyl value 109, PTMG-1000, manufactured by Sanyo Chemical Industry Co., Ltd.) 1
37.1 g and 3-methyl 1,5-pentanediol (hydroxyl value 950.8, MPD, manufactured by Kuraray Co., Ltd.) 48.9
g was added, and the mixture was stirred under a nitrogen atmosphere so as to be uniform. Hexamethylene diisocyanate (HMD
I, manufactured by Sumitomo Bayer Urethane Co., Ltd.) 146.4 g was added with stirring, and then 0.2 g of dibutyltin dilaurate was added.
Was added and reacted at 50 ° C. for 4 hours to obtain a urethane prepolymer having an isocyanate group of 8.19%.

To this, 92 g of 3,4-epoxycyclohexylmethanol (epoxy equivalent, 142, manufactured by Daicel Chemical Industries, Ltd.) was added, and the mixture was reacted at 70 ° C. for about 6 hours at 70 ° C. until the isocyanate groups disappeared, and methyl isobutyl ketone 148 was added. Diluted with 0.9 g. Then, 609.4 g of bisphenol A was added and dissolved, and then 0.6 g of zinc borofluoride was added and reacted at 100 ° C. until the epoxy group was substantially eliminated. Furthermore, bisphenol diglycidyl ether 12 having an epoxy equivalent of 190
72.6 g and diethanolamine 21 g were added,
The reaction was carried out at 0 ° C. until the epoxy group concentration reached 0.727 mmol / g. Then, it was diluted with 555.6 g of ethylene glycol monobutyl ether and cooled, and when the temperature reached 90 ° C., 173.3 g of diethanolamine was added and reacted until the epoxy groups disappeared. Solid content 78%, primary hydroxyl group equivalent 676, amine value 41 A urethane-modified epoxy-polyamine resin (A-1) having 0.5 was obtained.

Production Example 2 126.5 g of polypropylene glycol (hydroxyl value 118.1, PP-950, Sanyo Kasei Co., Ltd.) and 1,6-hexanediol (hydroxyl value 950.8) were placed in the same reactor as in Production Example 1. ) 53.3 g was added, and the mixture was stirred under a nitrogen atmosphere so as to be uniform. To this, 152.6 g of hexamethylene diisocyanate (HMDI, manufactured by Sumitomo Bayer Urethane Co., Ltd.) was added with stirring, and then 0.2 g of dibutyltin dilaurate was added and reacted at 50 ° C. for 4 hours to give 8.19% of isocyanate groups. A urethane prepolymer having the above was obtained.

To this, 92 g of 3,4-epoxycyclohexylmethanol (epoxy equivalent, 142, manufactured by Daicel Chemical Industries, Ltd.) was added, and the mixture was reacted in a nitrogen atmosphere at 70 ° C. for about 6 hours until the isocyanate groups disappeared, and methyl isobutyl ketone 148 was added. Diluted with 0.9 g. Then, 609.4 g of bisphenol A was added and dissolved, and then 0.6 g of zinc borofluoride was added and reacted at 100 ° C. until the epoxy group was substantially eliminated. Furthermore, bisphenol diglycidyl ether 12 having an epoxy equivalent of 190
72.6 g and diethanolamine 21 g were added,
The reaction was carried out at 0 ° C. until the epoxy group concentration reached 0.727 mmol / g. Then, it was diluted with 555.6 g of ethylene glycol monobutyl ether and cooled, and when the temperature reached 90 ° C., 173.3 g of diethanolamine was added and reacted until the epoxy groups disappeared. Solid content 78%, primary hydroxyl group equivalent 676, amine value 41 A urethane-modified epoxy-polyamine resin (A-2) having 0.5 was obtained.

Production Example 3 126.5 g of polypropylene glycol (hydroxyl value 118.1, PP-950, Sanyo Kasei Co., Ltd.) and 1,6-hexanediol (hydroxyl value 950.8) were placed in the same reactor as in Production Example 1. ) 46.3 g was added, and the mixture was stirred under a nitrogen atmosphere so as to be uniform. To this, 159.6 g of xylylene diisocyanate (Takenate 500, manufactured by Takeda Chemical Industries, Ltd.) was added with stirring, and then 0.2 g of dibutyltin dilaurate was added and reacted at 50 ° C. for 4 hours to give an isocyanate group of 8.19%. A urethane prepolymer having

To this, 92 g of 3,4-epoxycyclohexylmethanol (epoxy equivalent, 142, manufactured by Daicel Chemical Industries, Ltd.) was added, and the mixture was reacted at 70 ° C. for about 6 hours at 70 ° C. until the isocyanate groups disappeared, and methyl isobutyl ketone 148 was added. Diluted with 0.9 g. Then, 609.4 g of bisphenol A was added and dissolved, 0.6 g of zinc borofluoride was added, and the mixture was reacted at 100 ° C. until the epoxy group was substantially eliminated. Furthermore, bisphenol A diglycidyl ether 12 with an epoxy equivalent of 190
72.6 g and diethanolamine 21 g were added,
The reaction was carried out at 0 ° C. until the epoxy group concentration reached 0.727 mmol / g. Then, it was diluted with 555.6 g of ethylene glycol monobutyl ether and cooled, and when the temperature reached 90 ° C., 173.3 g of diethanolamine was added and reacted until the epoxy groups disappeared. Solid content 78%, primary hydroxyl group equivalent 676, amine value 41 A urethane-modified epoxy-polyamine resin (A-3) having 0.5 was obtained.

Production Example 4 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
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 (A-4) having a solid content of 78%, a primary hydroxyl group equivalent of 541 and an amine value of 51.8 was obtained.

Production Example 5 425.3 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 120 ° C
Then, the mixture was reacted until the epoxy group concentration reached 0.727 mmol / g, then diluted and cooled with 555.2 g of ethylene glycol monobutyl ether, and when it reached 90 ° C, 173.3 g of diethanolamine was added, and the reaction was continued until the epoxy group disappeared. Thus, a modified epoxy-polyamine resin (A-5) 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) was added to a solution having an amount corresponding to 100 g of the solid content of the resin composition.
4000) 1 g, acetic acid 1.82 g and curing catalyst shown in Table 1 in a solid amount of 2 g, and 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, 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 surface of the coated film after it was strongly rubbed 10 times with absorbent cotton containing ethyl cellosolve back and forth. Sample Nos. 1 to 8 are comparative examples.
-12 are Examples of the present invention. The evaluation was judged according to the following criteria. It has a strong coating surface and no 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, the samples (No. 9 to 12) of the combined use system of the organotin compound and the lanthanum compound of the present invention are the samples using the conventionally used tin catalyst (No. 2 to 5) and Samples using the organotin compound used in the present invention alone (No. 6 to
It can be seen that the low temperature curability of the electrodeposition coating film is very excellent as compared with 8).

[0077]

[Table 1]

Examples 1 to 6 and Comparative Examples 1 to 4 Methyl ethyl ketoxime block isophorone diisocyanate was added to the five resin solutions obtained in the above Production Examples 1 to 5 in the ratio shown in Table 3. To 100 g of the solid content of each of the resin compositions, 1 g of polypropylene glycol (manufactured by Sanyo Kasei Co., Sannix PP4000), tin compounds having the formulations 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.

[0079]

[Table 2]

Example 7 Methyl ethyl ketoxime block isophorone diisocyanate was added to the resin solution obtained in the above Production Example 1 in the ratio shown in Table 3. 1 g of polypropylene glycol (manufactured by Sanyo Kasei Co., Ltd., Sannix PP4000), a tin compound having the composition shown in Table 3 and acetic acid were added to 100 g of the solid content of the resin composition, and the mixture was stirred uniformly and then a 10% lanthanum acetate aqueous solution was added. 10 g (1 g in terms of solid content) was added, deionized water was gradually added to the solution by heating to 40 ° C. and stirring to disperse it in water to obtain a clear emulsion for cationic electrodeposition coating having a resin solid content of 35%. This clear emulsion 286
69.7 g of the pigment paste of the formulation 3 shown in Table 2 above was added to g with stirring, and the resin solid content was further increased to 15 with deionized water.
It was diluted so that it became 10% to obtain the electrodeposition coating material of Example 7.

Coating test Each electrodeposition coating 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 methods in Table 3 were 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, the Dupont impact tester has a pedestal of a specified size. 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 on the shooting target, and the maximum height (cm) at which there was no cracking 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 to a bending tester (10 mmφ). Do it. When there was no abnormality on both the front and back sides of the bent portion, it was evaluated as ◯, and when there was abnormality such as cracks or peeling on at least one of them, it was evaluated as x.

* 3 Salt spray resistance A cross-cut was put in a test plate and a salt spray test was conducted according to JIS Z2871, and after 840 hours, a cellophane tape was adhered to the cross-cut part and the peeling width (one side, cm ) Was measured.

* 4 Curability The coating surface of each test plate was rubbed with 4 layers of gauze soaked with methyl isobutyl ketone at a pressure of about 4 kg / cm ² for 20 reciprocations about 3 to 4 cm in length. The surface appearance was visually evaluated. ◯: No scratch is observed on the coated surface. Δ: A scratch is observed on the coated surface, but the base material is not visible. X: The coating film is dissolved and the base material is visible.

* 5 Bath stability After stirring the coating material at 30 ° C. for 1 month, 400
Filtration was performed with a mesh wire mesh, and the amount of residue on the wire mesh was evaluated. ◯: Residue amount 0 to 10 mg / 1 or less Δ: Residue amount 10 mg / 1 or more to 100 mg / 1 or less X: Residue amount 100 mg / 1 or more

[0088]

[Table 3]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location C08G 59/68 NKM 8416-4J (72) Inventor Yoshio Yasuoka 4-chome 1-17 Higashihachiman, Hiratsuka-shi, Kanagawa Issue Kansai Paint Co., Ltd.

Claims (3)

[Claims] 1. A polyhydroxy compound (a) having a number average molecular weight of 50 to 8,000, a polyisocyanate compound (b), and a compound having one hydroxyl group and at least one alicyclic epoxy group in one molecule ( From a reaction product of an epoxy group-containing polyurethane compound (A) composed of c), a bisphenol compound (B), a bisphenol diglycidyl ether compound (C), and an amine compound (D) having active hydrogen. The following polyurethane-modified epoxy-polyamine resin and an alkyltin ester compound of an aromatic carboxylic acid represented by the following formulas (I) and (II): [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), and at least one lanthanum compound. An electrodeposition coating composition comprising: 2. The electrodeposition coating composition according to claim 1, which contains a blocked polyisocyanate as a crosslinking agent for the polyurethane-modified epoxy-polyamine resin. 3. The electrodeposition coating composition according to claim 1, wherein the lanthanum compound is lanthanum acetate.