JP3447821B2 - Cationic electrodeposition coating composition - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cationic electrodeposition coating composition, and more particularly to a cationic electrodeposition coating composition having both corrosion resistance during low temperature baking and pigment dispersion stability.

[0002]

2. Description of the Related Art A cationic electrodeposition coating composition for providing a corrosion-resistant coating on an object to be coated such as an automobile is a pigment paste containing a cationic resin, a curing agent, and a pigment dispersed by a pigment dispersion resin dispersed in an aqueous medium. It will be provided in the designated form.

In recent years, in order to reduce energy costs, it has been required to bake the above cationic electrodeposition coating material at a low temperature for a short time. On the other hand, cationic electrodeposition coatings naturally require pigment dispersion stability. It is difficult for these two conditions to be compatible with each other in the technologies so far.

For example, when a resin containing a quaternary ammonium salt is used as the pigment dispersion resin, the pigment dispersion stability is excellent, but the corrosion resistance is not sufficient during so-called low temperature baking at 160 ° C. or lower.

It has also been proposed to use a tertiary sulfonium salt as a pigment dispersing resin. When this pigment-dispersed resin is used, the corrosion resistance during low-temperature baking is excellent, but the pigment dispersion stability is poor, and the stability of the coating bath is insufficient.

Further, a pigment dispersion resin containing an acid-neutralized salt of a tertiary amine has been proposed, but it has the same drawbacks as the pigment dispersion resin using the sulfonium salt.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a cationic electrodeposition coating composition which has both dispersion stability of a pigment and corrosion resistance at 160 ° C. or lower, that is, so-called low temperature baking.

[0008]

That is, the present invention provides a pigment paste containing (A) a cationic resin, (B) a low temperature dissociative blocked isocyanate curing agent, and (C) a pigment dispersed in a pigment dispersion resin. Which has a SP value of 10.0 to 11.0 before the cationization of the resin for dispersing the pigment, and has a primary amino group in the molecule of 1.6. To 4.0, and the ratio of each component is A / B / C = 10 to 88/10 to 50/2 to 50
A cationic electrodeposition coating composition is provided.

The cationic resin that can be used in the present invention can be any known cationic resin. For example, Japanese Patent Publication Sho 54
Amine-modified epoxy resin systems such as -4978 and 56-34186, amine-modified polyurethane polyol resin systems such as 55-115476, JP-B-62-61
077, amine-modified polybutadiene resin systems such as JP-A-63-86766, JP-A-63-139909,
Examples thereof include amine-modified acrylic resin systems such as Japanese Patent Publication No. 1-60516. Resin systems containing sulfonium groups and resin systems containing phosphonium groups are also known. A preferred cationic resin is an amine-modified cationic resin.

The chaotic resin (A) is added in an amount of 10 to 88% by weight, preferably 30 to 70% by weight, based on the solid content of the coating material. If it exceeds 88% by weight, the curability is insufficient and 10
If it is less than wt%, the rust preventive performance will decrease.

The cationic electrodeposition coating composition of the present invention comprises a block polyisocyanate having a dissociation temperature of 100 to 160 ° C.
Contains (B). The blocked polyisocyanate (B) may be present in the composition as a separate component or may be integrated with the other components. For example, the half-blocked polyisocyanate may be reacted with the cationic resin (A) to give the cationic resin (A) crosslinking ability. When the block polyisocyanate is not contained, the curability is insufficient, and when the dissociation temperature of the block polyisocyanate is less than 100 ° C., the fluidity of the coating film is very poor and the smoothness of the flat surface portion is lowered, which is not preferable. . There is also a problem with the stability of the paint. On the other hand, when the dissociation temperature exceeds 160 ° C., the curability at the time of low temperature baking, which is the object of the present invention, becomes insufficient and the anticorrosion property deteriorates.

As the block polyisocyanate having a dissociation temperature of 100 ° C. to 160 ° C., all polyisocyanates conventionally used as a vehicle component for electrodeposition coatings can be used, but it is necessary to select a blocking agent in low temperature curing. is there. Representative polyisocyanates are exemplified below. Trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, ethylidene diisocyanate,
Aliphatic diisocyanates such as butylidene diisocyanate, 1,3-cyclopentane diisocyanate, 1,4
-Cyclohexane diisocyanate, 1,2-cyclohexane diisocyanate, aliphatic cyclic diisocyanate such as isophorone diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate,
Aromatic diisocyanates such as 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 1,4-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4- or 2,6-toluene diisocyanate or mixtures thereof 4,4 '
-Aliphatic-aromatic diisocyanates such as toluidine diisocyanate, 1,4-xylene diisocyanate,
Nuclear-substituted aromatic diisocyanates such as dianisidine diisocyanate, 4,4′-diphenyl ether diisocyanate and chlorodiphenyl diisocyanate, triphenylmethane-4,4 ′, 4 ″ -triisocyanate, 1,3,
5-triisocyanate benzene, 2,4,6-triisocyanate triisocyanate such as toluene, 4,4 ′
There are tetraisocyanates such as -diphenyl-dimethylmethane-2,2 ', 5,5'-tetraisocyanate, and polymerized polyisocyanates such as toluene diisocyanate dimer and toluene diisocyanate trimer.

The blocking agent which dissociates at a temperature of 100 to 160 ° C. may be in the presence of a catalyst. Such blocking agents include, for example, in the case of aromatic polyisocyanates, halogenated hydrocarbons such as 1-chloro-2-propanol and ethylene chlorohydrin, n-
Aliphatic or heterocyclic alcohols such as propanol, furfuryl alcohol, and alkyl group-substituted furfuryl alcohol, phenols such as phenol, m-cresol, p-nitrophenol, p-chlorophenol, and nonylphenol, methyl ethyl ketone oxime, methyl isobutyl Examples include oximes such as ketone oxime, acetone oxime, cyclohexane oxime, active methylene compounds such as acetylacetone, ethyl acetoacetate, ethyl malonate, and caprolactam. Particularly preferred are oximes, phenols, alcohols. Then, it is a furfuryl alcohol and a furfuryl alcohol substituted with an alkyl group. In the case of aliphatic polyisocyanate, phenols and oximes are preferable among the above.

When a dissociation catalyst for the blocked polyisocyanate curing agent (B) is used, an organotin compound such as dibutyltin laurate, dibutyltin oxide or dioctyltin, or an organic tin compound,
Amines such as N-methylmorpholine and metal salts such as lead acetate, strontium, cobalt and copper can be used. The concentration of the catalyst is usually 0.1 to 6% by weight based on the solid content of the film-forming resin in the cationic electrodeposition coating composition.

The content of the blocked polyisocyanate curing agent (B) in the composition is 10 to 50% by weight, preferably 15 to 40% by weight, based on the solid content of the coating composition. 10% by weight
If it is less than 50% by weight, it has a drawback of insufficient curability, and if it exceeds 50% by weight, a large amount of desorbed substances are generated during baking of the coating film, so that the smoothness of the coating film is deteriorated and a large amount of tar and smoke cause pollution. There's a problem.

The pigment-dispersing resin used in the pigment paste of the present invention is obtained by introducing a primary amino group into a hydrophobic resin and then neutralizing it with an acid. Hydrophobic resin is SP
It has a value of 10.0 to 11.0 and the average number of amino groups introduced into it is 1.6 to 4.0 per molecule.

The most preferable pigment-dispersing resin used in the present invention is obtained by reacting a bisphenol A type epoxy resin with an isocyanate having an isocyanate residue of 1.0 to 0.5 molar equivalent in one molecule. A hydrophobic epoxy resin obtained by introducing a primary amino group is preferred.

The epoxy resin used in the present invention is generally a polyepoxide. This polyepoxide has an average of one or more 1,2-epoxy groups in one molecule. These polyepoxides preferably have an epoxy equivalent of 180 to 1000, in particular 375 to 800. If the epoxy equivalent is less than 180, a film cannot be formed during electrodeposition and a coating film cannot be obtained. When it exceeds 1,000, the amount of cationic groups per molecule is insufficient and sufficient water solubility cannot be obtained.

Useful classes of such polyepoxides include polyglycidyl ethers of polyphenols (eg, bisphenol A). These are, for example:
It is prepared by etherifying polyphenol with epichlorohydrin or dichlorohydrin in the presence of alkali. This polyphenol is bis (4-
It can be hydroxyphenyl) -2,2-propane, 4,4'-dihydroxybenzophenone, bis (4-hydroxyphenyl) -1,1-ethane or the like.

The isocyanate used in the present invention for reacting with the above-mentioned epoxy resin is an isocyanate in which the residue of the isocyanate in one molecule has 1.0 to 0.5 molar equivalent, and is produced by reacting with the epoxy resin. There is no particular limitation as long as the SP value of the hydrophobic epoxy resin can be adjusted to 10.0 to 11.0. The introduction of isocyanate groups makes the epoxy resin more hydrophobic.

Examples of isocyanates used in the present invention include monoisocyanates such as butyl isocyanate and half-blocked isocyanates prepared by partially blocking organic polyisocyanates. Is preferably used.

The reaction between the organic polyisocyanate and the blocking agent may be carried out in the presence of a tin catalyst, if necessary, by cooling the mixture to 40 to 50 ° C. while dropping the blocking agent while stirring. preferable. The reaction ratio between the organic polyisocyanate and the blocking agent is such that the isocyanate residue in one molecule of the half-blocked isocyanate produced is 1.0 to 0.5 molar equivalent, preferably 0.99 to 0.0.
The reaction ratio of the blocking agent can be determined by stoichiometric calculation so that the molar ratio is 80 molar equivalents. If the isocyanate residue exceeds 1.0 molar equivalent, gelation may occur during reaction with the epoxy resin. When the amount is less than 0.5 molar equivalent, the total blocked isocyanate that remains without reacting with the epoxy resin increases and water solubility is impaired, which is not preferable.

The organic polyisocyanate that can be used is not particularly limited as long as it has an average of two or more isocyanate groups in one molecule. As typical examples, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-
Aliphatic diisocyanates such as butylene diisocyanate, 1,3-butylene diisocyanate, ethylidyne diisocyanate and butylidene diisocyanate,
Aliphatic cyclic compounds such as 1,3-cyclopentane diisocyanate, 1,4-cyclohexane diisocyanate and 1,2-cyclohexane diisocyanate, isophorone diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, Aromatic diisocyanates such as 1,5-naphthalene diisocyanate and 1,4-naphthalene diisocyanate, 4,4'-diphenylene methane diisocyanate, 2,4- or 2,6-
Tolylene diisocyanate, or a mixture thereof, 4,
Aliphatic-aromatic diisocyanates such as 4'-toluidine diisocyanate and 1,4-xylylene diisocyanate, dianisidine isocyanate, 4,4'-
Nuclear substituted aromatic diisocyanates such as diphenyl ether diisocyanate and chlorodiphenylene diisocyanate, triphenylmethane-4,4 ', 4 "-triisocyanate, 1,3,5-triisocyanate benzene and 2,4,6-triisocyanate toluene , Tetraisocyanates such as 4,4'-diphenyldimethylmethane-2,2 ', 5,5'-tetraisocyanate, polymerized polyisocyanates such as tolylene diisocyanate dimers and trimers, etc. Is mentioned.

The polyisocyanate used in the present invention preferably has isocyanate groups having various reactivities which facilitate the partial blocking reaction. Suitable blocking agents for preparing half-blocked isocyanates are lower aliphatic alkyl monoalcohols having 4 to 20 carbon atoms. If the number of carbon atoms contained in the blocking agent is less than 4, a proper SP value cannot be obtained,
If it exceeds the range, the anticorrosive property is deteriorated, which is not preferable. Specifically, lower fatty acids such as butyl alcohol, amyl alcohol, hexyl alcohol, 2-ethylhexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, 3,3,5-trimethylhexanol, decyl alcohol, lauryl alcohol and stearyl alcohol. Group alcohols are mentioned.

Then, the above-mentioned epoxy resin is reacted with a half-blocked isocyanate to obtain a hydrophobic epoxy resin. The reaction is preferably carried out by keeping at 140 ° C. for about 1 hour. The reaction ratio between the epoxy resin and the half-blocked isocyanate is 1: 0.5-
It is preferably set to 1: 2.5. The reaction is carried out by tracing using IR until the isocyanate group is substantially disappeared.

In this reaction, the hydroxyl group contained in the epoxy resin and the unblocked isocyanate group in the half-blocked isocyanate bond to each other to improve the hydrophobicity of the epoxy resin. By that,
The pigment-dispersed paste containing the cationic resin as a dispersant obtained by using this has dispersion stability. The hydrophobic epoxy resin is preferably 10.0-11.
It has an SP value of 0, more preferably 10.2 to 10.6. The SP value is an index showing the polarity of the resin, and for example,
It can be measured using a turbidity method by titration with water or hexane. When the SP value of the hydrophobic epoxy resin exceeds 11.0, the hydrophobicity of the resin decreases and the interaction with the pigment becomes poor, so that the dispersion stability of the pigment dispersion paste becomes insufficient and becomes less than 10.0. Since the hydrophilicity of the resin becomes poor, the storage stability as an aqueous electrodeposition coating becomes poor. The SP value of the hydrophobic epoxy resin can be adjusted by appropriately selecting the reaction ratio of the half blocked isocyanate and the blocking agent for preparing the half blocked isocyanate.

Then, a primary amino group is introduced into the obtained hydrophobic epoxy resin and neutralized to impart hydrophilicity. This makes it possible to obtain an electrodeposition coating composition that exhibits dispersibility and storage stability when the pigment-dispersed paste is diluted with an aqueous medium. In the present invention, the introduction of the primary amino group is carried out by the reaction between the partially ketimine-capped polyamine and the epoxy group in the hydrophobic epoxy resin. The cap of the ketimine-capped polyamine is removed to regenerate the primary amino group and neutralize it to render it hydrophilic. The partially ketimine-capped polyamine is obtained by reacting a polyamine compound with a ketone in an amount such that a part of the primary amine is capped.

Examples of the polyamine compound used in the present invention include diethylenetriamine, aminoethylethanolamine, aminoethylpiperazine and the like. These polyamines are reacted with ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone to give ketimine derivatives. The ketimine production reaction proceeds easily by heating at 100 ° C. or higher and distilling off the produced water.

The reaction between the partially ketimine-capped polyamine and the epoxy resin is carried out under the condition of being kept at 120 ° C. for 1 hour, then cooled to 90 ° C., and an appropriate amount of pure water is regenerated to regenerate the primary amino group. The primary amino group that had been ketiminated is regenerated.

Further, the primary amino group may be amidated with anhydrous acid to adjust the introduction amount. The amide group is generally a hydrophilic group, and by introducing the amide group, the water solubility of the pigment dispersion resin can be supplemented regardless of the amino group. Those having 1.6 to 4.0 primary amino groups in one molecule are amidated with anhydrous acid to average 1.0 to 3.0 primary amino groups in one molecule, preferably 1.2 to 2 on average. .Adjust to have four. By introducing an amide group, paint workability such as re-solubility can be improved without lowering water solubility. Examples of the acid anhydride used for amidation include propionic acid anhydride and acetic anhydride, with acetic anhydride being preferred. The number of amide groups in one molecule is preferably on average 0.
The number is 6 to 3.0, and more preferably 0.8 to 2.0.

The pigment paste of component (C) of the present invention is a mixture of the above pigment dispersion resin and a suitable pigment. Examples of pigments that can be used are coloring pigments such as carbon black, graphite, titanium oxide and zinc white, extender pigments such as aluminum silicate and kaolin, strontium chromate, basic lead silicate, basic lead sulfate and molybdenum phosphonate. Synthetic pigments such as aluminum oxide can be used. The concentration of the pigment is 1 to 35% by weight, preferably 10 to 30% by weight, based on the total solid content of the electrodeposition coating composition. The amount of the pigment-dispersed resin used depends on the amount of the above-mentioned pigment, but is 1 to 20% by weight, preferably 1 to 15% by weight based on the total solid content of the electrodeposition coating composition.
Is.

The cationic electrodeposition coating composition of the present invention may contain various additives and solvents, if necessary, in addition to the above components.

Examples of the additives include acids such as formic acid, acetic acid, lactic acid and sulfamic acid used for dispersing the film-forming component in an aqueous medium, and a surfactant.
The concentration of these additives is usually 0.1 to 15% by weight, preferably 0.1 to 5% by weight, based on the resin solid content in the electrodeposition coating composition.

The cationic electrodeposition coating composition of the present invention is dispersed in an aqueous medium, but various organic solvents other than water may be used in the aqueous medium for adjusting the dissolution and viscosity of the resin. Good. Examples of the solvent that can be used are hydrocarbons (eg, xylene or toluene), alcohols (eg, methyl alcohol, n-butyl alcohol, isopropyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, propylene glycol), ethers ( For example, ethylene glycol monoethyl ether,
Ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, propylene glycol monoethyl ether, 3-methyl-3-methoxybutanol, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether), ketones (for example, methyl isobutyl ketone, cyclohexanone, isophorone, acetylacetone) ), Esters (for example, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate) and a mixture thereof. The amount of these solvents used is about 0.01 to 25% by weight, preferably 0.05 to 15% by weight, based on the entire coating composition.

In the electrodeposition coating carried out in the present invention, the coating bath temperature is 20 to 40 ° C., the applied voltage is 50 to 500 V, and the energization time is 30 seconds to 30 seconds when the object to be coated is completely immersed in the coating bath. 1
It is performed under the condition that has been conventionally used such as 0 minutes. The required thickness of the electrodeposition coating film is 5 to 50 μm as a baking coating film,
It is preferably 10 to 35 μm.

The baking of the electrodeposition coating film in the present invention is carried out at a temperature of an object to be coated of 100 ° C to 200 ° C, preferably 130 ° C to 16 ° C.
It is 0 ° C., and usually 5 minutes to 50 minutes. However, 1
Even when baked at a high temperature of 60 ° C. or higher, the anticorrosive property according to the present invention does not deteriorate.

The metal material to which the method of the present invention can be applied is a metal which has been hitherto generally electrodeposited, such as iron or copper.
It may be a galvanized material, aluminum, an alloy thereof, or the like, or may be one that has been subjected to chemical conversion treatment.

[0038] Examples will be specifically described in the present invention embodiment. Unless otherwise noted, "part" means part by weight.

Preparation Example 1 Preparation of Polyurethane Crosslinking Agent A A hexamethylene diisocyanate 840 was placed in a reaction vessel equipped with a stirrer, a cooling tube, a nitrogen introducing tube and a thermometer.
Parts, and diluted with 609 parts of methyl isobutyl ketone (hereinafter abbreviated as MIBK), 0.9 parts of dibutyl tin laurate was added, and after heating to 50 ° C., trimethylolpropane (hereinafter abbreviated as TMP) 223. Five parts were gradually added so that the resin temperature did not exceed 60 ° C. Next, methityl ethyl ketoxime (hereinafter abbreviated as MEK oxime)
435 parts were added so that the resin temperature did not exceed 70 ° C.
Hold at 70 ° C. for 1 hour until the absorption of the isocyanate group is substantially extinguished from the infrared absorption spectrum, and then n-
Diluted with 32 parts butanol (resin solids 70.0
%).

Preparation Example 2 Preparation of aminated epoxy resin A bisphenol A type epoxy resin (Epototo YD-014 Toto Kasei Co., Ltd.) having an epoxy equivalent of 950 was placed in a reaction vessel equipped with a stirrer, a cooling tube, a nitrogen introducing tube and a thermometer. ) 950 parts were heated to 100 ° C. together with MIBK237.5 parts and completely dissolved. Then, diethylenetriamine in methylisobutyldiketimine 73% MIBK solution 7
3.4 parts and further 60.1 parts of n-methylethanolamine were added, the mixture was heated to 115 ° C., reacted for 1 hour and then taken out (resin solid content 80.5%).

[0041] Preparation Example 3 for cationic electrodeposition paint main preparation component aqueous dispersion A of resin parts aminated epoxy resin (Preparation Example 2) 832.3 Polyurethane crosslinking agent A (Preparation Example 1) 471.4 n-hexyl Cellosolve 65.0 Glacial acetic acid 18.5 Deionized water 1737.8

The aminated epoxy resin obtained in Preparation Example 2 according to the above composition and the polyurethane cross-linking agent A obtained in Preparation Example 1 were mixed with n-hexyl cellosolve, neutralized with glacial acetic acid and then deionized water. And slowly diluted. Then, the organic solvent was removed under reduced pressure until the solid content became 36.0% to obtain an aqueous dispersion A of a main resin for cationic electrodeposition coating.

Preparation Example 4 Preparation of Polyurethane Crosslinking Agent B A reaction vessel equipped with a stirrer, a cooling tube, a nitrogen introducing tube and a thermometer was charged with isophorone diisocyanate (hereinafter referred to as I
PDI) (1110 parts) is added and diluted with MIBK (719 parts), and then dibutyl tin laurate (1.1 parts) is added.
After raising the temperature to 50 ° C, the resin temperature of TMP223.5 parts is 60
It was added gradually so that the temperature did not exceed ℃. Then, 435 parts of MEK oxime was added so that the resin temperature did not exceed 70 ° C. Hold at 70 ° C for 1 hour until the absorption of the isocyanate group is substantially extinguished according to the infrared absorption spectrum, and then
Diluted with 38 parts of n-butanol (resin solids 70.0.
%).

Preparation Example 5 Preparation of polycaprolactone diol chain-extended polyether In a reaction vessel equipped with a stirrer, a cooling tube, a nitrogen introducing tube and a thermometer, a bisphenol A type epoxy resin having an epoxy equivalent of 190 (Epicoat 828 oiled shell Epoxy Co., Ltd.) 690 parts, polycaprolactone polyol (Molecular weight 500, Daicel Chemical Industries Co., Ltd.) 250 parts, bisphenol A 198 parts and MIBK 59.9 parts, and benzyl dimethylamine 1.5 parts in the presence of 180 ° C. for 1 hour, Furthermore, 2.2 parts of benzyldimethylamine was added and reacted at 150 ° C. for 4 hours with an epoxy equivalent of 110.
A product with 0 was obtained. MIBK137.
After adding 2 parts and cooling to 100 ° C., methylisobutyldiketimine of diethylenetriamine 73% MIBK
72.3 parts of solution, and further n-methylethanolamine 5
9.1 parts were added and the mixture was heated to 115 ° C. and reacted for 1 hour. Then, it was diluted with 132 parts of MIBK to obtain a resin varnish (resin solid content: 78.0%).

Preparation Example 6 Preparation Component of Aqueous Dispersion B of Main Resin for Cationic Electrodeposition Coating Parts by Weight Polycaprolactonediol Chain Extension 859.0 Polyether (Preparation Example 5) Polyurethane Crosslinking Agent B (Preparation Example 4) 471.4 n-hexyl cellosolve 50.0 glacial acetic acid 15.5 deionized water 1729.1

The polycaprolactone diol chain-extended polyether obtained in Preparation Example 5 according to the above composition and the polyurethane cross-linking agent B obtained in Preparation Example 4 were mixed with n-hexyl cellosolve and neutralized with glacial acetic acid. Deionized water was added to slowly dilute. Then, this is solid content 3
The organic solvent was removed under reduced pressure to 6.0% to obtain an aqueous dispersion B of the main resin for cationic electrodeposition coating.

Preparation Example 7 Preparation of Acrylic Cationic Resin A reaction vessel equipped with a stirrer, a cooling tube, a nitrogen introducing tube and a thermometer was charged with 45 parts of ethylene glycol monohexyl ether and heated to 120 ° C. To this 20 parts of styrene, 30 parts of 2-hydroxyethyl methacrylate
Part, ethyl acrylate 35 parts, dimethylaminoethyl methacrylate 15 parts, t-dodecyl mercaptan 3
Part and azobisisobutyronitrile 2 parts were added dropwise over 2 hours. After the dropping was completed, the mixture was kept at 120 ° C. for 30 minutes, and then ethylene glycol monohexyl ether 5
Part of azobisisobutyronitrile 0.2 parts
The mixture was added dropwise over a period of minutes, and then held at 120 ° C. for 1 hour to obtain an acrylic copolymer varnish having a resin solid content of 68.0% and a weight average molecular weight of about 10,000.

Preparation Example 8 Preparation Component of Water Solution C of Main Resin for Cationic Electrodeposition Coating Part by Weight Acrylic Cationic Resin 1176.5 (Preparation Example 7) Polyurethane Crosslinking Agent B (Preparation Example 4) 285.7 Glacial Acetic Acid 17 .4 Deionized water 1298.2

The acrylic cationic resin obtained in Preparation Example 7 and the polyurethane cross-linking agent B obtained in Preparation Example 4 were mixed according to the above constitution, neutralized with glacial acetic acid, and deionized water was added slowly. It was diluted and obtained by adding an aqueous dispersion C of a main resin for cationic electrodeposition coating having a solid content of 36.0%.

Example 1 A reaction vessel equipped with a stirrer, a cooling pipe, a nitrogen introducing pipe and a thermometer was placed in an isophorone diisocyanate (hereinafter referred to as IP
222.0 parts of DI) was added and diluted with 39.1 parts of methyl isobutyl ketone (hereinafter abbreviated as MIBK), 0.2 parts of dibutyltin laurate was added, and the temperature was raised to 50 ° C., and then 2-ethyl was added. 131.5 parts of hexanol (hereinafter abbreviated as 2EH) was added dropwise under stirring in a dry nitrogen atmosphere over 2 hours. The reaction temperature is adjusted to 5 by appropriately cooling.
Maintained at 0 ° C. As a result, 2-ethylhexanol half-blocked IPDI was obtained (resin solid content 90.0
%).

Then, in accordance with the composition shown in the table below, Epicoat 828 and bisphenol A were charged into a reaction vessel equipped with a stirrer, a cooling tube, a nitrogen introducing tube and a thermometer, and heated to 130 ° C. in a nitrogen atmosphere to obtain dimethylbenzylamine. Was added and reacted at 170 ° C. for 1 hour under an exothermic reaction to obtain a bisphenol A type epoxy resin having an epoxy equivalent of 490. Then 140
After cooling to ° C, 2-ethylhexanol half blocked IPDI was added. The mixture was kept at 140 ° C. for 1 hour for reaction to obtain a hydrophobic epoxy resin having an SP value of 10.6. After adding ethylene glycol monobutyl ether to dilute, the reaction mixture was cooled to 100 ° C. and a solution of aminoethylethanolamine in methylisobutylmonoketimine 78.8% MIBK was added. This mixture was kept at 110 ° C. for 1 hour and then cooled to 90 ° C., deionized water was added and stirring was continued for another 30 minutes to regenerate the ketiminized primary amino group. Excess water and MIBK were removed from this mixture under reduced pressure, and then diluted with ethylene glycol monobutyl ether to obtain a pigment dispersion resin varnish A (resin solid content 50%).

Ingredients by weight Epicoat 828 376.0 Bisphenol A 114.0 Benzyldimethylamine 0.15 2-Ethylhexanol half-blocked IPDI 198.4 Ethylene glycol monobutyl ether 266.6 Methylisobutyl of aminoethylethanolamine 236.0 Monoketimine 78.8% MIBK solution Deionized water 360.0 Ethylene glycol monobutyl ether 486.1

The epoxy equivalent of the bisphenol A type epoxy resin used here, the number of moles of half-blocked isocyanate added to one molecule of the epoxy resin, the number of ketimine groups with respect to the epoxy groups, and the SP value of the hydrophobic epoxy resin were determined as follows. It is shown in Table 1 together with the results obtained in Examples 2-6 and Comparative Examples 1-4.

Example 2 Ingredients by weight Epicoat 828 376.0 Bisphenol A 114.0 Benzyldimethylamine 0.15 2-Ethylhexanol half-blocked IPDI 198.4 Ethylene glycol monobutyl ether 266.6 Diethyltriamine methylisobutyldiketimine 367 0.073% MIBK solution Deionized water 360.0 Ethylene glycol monobutyl ether 449.1 According to the above composition, by reacting under the same reaction conditions as in Example 1, a cationic resin for pigment dispersion was obtained, and a varnish B for pigment dispersion was obtained. (Resin solid content 50%).

Example 3 Component parts by weight Epicoat 828 376.0 Bisphenol A 114.0 Nonylphenol 44.0 Benzyldimethylamine 0.15 2-Ethylhexanol half blocked IPDI 396.8 Ethylene glycol monobutyl ether 323.2 Aminoethylethanol Amine methylisobutyl 188.8 monoketimine 78.3% MIBK solution deionized water 360.0 ethylene glycol monobutyl ether 588.1

According to the above composition, the reaction was carried out under the same reaction conditions as in Example 1 except that Epicoat 828 and bisphenol A were placed in a reaction vessel equipped with a stirrer, a cooling tube, a nitrogen introducing tube and a thermometer, and nonylphenol was further added. By doing so, a cationic resin for pigment dispersion was obtained, which was used as a varnish C for pigment dispersion (resin solid content 50%).

Example 4 Component parts by weight Epicoat 828 568.9 Bisphenol A 231.1 Nonylphenol 44.0 Benzyldimethylamine 0.15 2-Ethylhexanol half-blocked IPDI 198.4 Ethylene glycol monobutyl ether 418.3 Methyl diethylenetriamine. Isobutyl diketimine 293.6 73% MIBK solution Deionized water 360.0 Ethylene glycol monobutyl ether 794.8

According to the above composition, a cationic resin for pigment dispersion was obtained by reacting under the same reaction conditions as in Example 3 to obtain a varnish D for pigment dispersion (resin solid content 50%).

Example 5 Ingredients by weight Epicoat 828 376.0 Bisphenol A 114.0 Nonylphenol 44.0 Benzyldimethylamine 0.15 2-Ethylhexanol half-blocked IPDI 99.2 Ethylene glycol monobutyl ether 257.1 Methyl diethylenetriamine Isobutyl diketimine 293.6 73% MIBK solution Deionized water 360.0 Ethylene glycol monobutyl ether 591.8

According to the above composition, a cationic resin for pigment dispersion was obtained by reacting under the same reaction conditions as in Example 3 to obtain a varnish E for pigment dispersion (resin solid content 50%).

Example 6 Ingredients by weight Epicoat 828 568.9 Bisphenol A 231.1 Nonylphenol 44.0 Benzyldimethylamine 0.15 2-Ethylhexanol half-blocked IPDI 496.0 Ethylene glycol monobutyl ether 503.4 Methyl diethylenetriamine. Isobutyl diketimine 293.6 73% MIBK solution Deionized water 360.0 Ethylene glycol monobutyl ether 1022.1

According to the above composition, a cationic resin for pigment dispersion was obtained by reacting under the same reaction conditions as in Example 3 to obtain a varnish F for pigment dispersion (resin solid content 50%).

Example 7 Ingredients by weight Epicoat 828 376.0 Bisphenol A 114.0 Nonylphenol 44.0 Benzyldimethylamine 0.15 2-Ethylhexanol half-blocked IPDI 198.4 Ethylene glycol monobutyl ether 285.5 Methyl diethylenetriamine. Isobutyl diketimine 293.6 73% MIBK solution Deionized water 14.4 Acetic anhydride 40.8 Ethylene glycol monobutyl ether 468.8

According to the above composition, the primary amino group is regenerated by reacting under the same reaction conditions as in Example 3 until the addition of deionized water. Then, the reaction mixture was cooled to 80 ° C., and acetic anhydride was added dropwise over 30 minutes. After MIBK was removed from this mixture under reduced pressure, it was diluted with ethylene glycol monobutyl ether to obtain a pigment dispersion resin varnish G. (Resin solid content 50%)

Comparative Example 1 component by weight Epicoat 828 376.0 Bisphenol A 114.0 Benzyldimethylamine 0.15 Ethylene glycol monobutyl ether 209.8 Aminoethylethanolamine methylisobutyl 236.0 Monoketimine 78.8% MIBK solution Desorption Ionized water 360.0 Ethylene glycol monobutyl ether 384.0

According to the above composition, a cationic resin for pigment dispersion was obtained by reacting under the same reaction conditions as in Example 1 except that 2-ethylhexanol half-blocked IPDI was not added to obtain a varnish H for pigment dispersion (resin 50% solids).

Comparative Example 2 components by weight Epicoat 828 376.0 Bisphenol A 114.0 Nonylphenol 88.0 Benzyldimethylamine 0.15 2-Ethylhexanol half-blocked IPDI 198.4 Ethylene glycol monobutyl ether 304.3 Aminoethylethanol Amine methylisobutyl 141.6 monoketimine 78.8% MIBK solution deionized water 360.0 ethylene glycol monobutyl ether 484.0

According to the above composition, a cationic resin for pigment dispersion was obtained by reacting under the same reaction conditions as in Example 3 to obtain a varnish I for pigment dispersion (resin solid content 50%).

Comparative Example 3 components by weight Epicoat 828 376.0 Bisphenol A 114.0 Benzyldimethylamine 0.15 2-ethylhexanol half-blocked IPDI 198.4 Ethylene glycol monobutyl ether 266.6 N-methylethanolamine 75. 1 Ethylene glycol monobutyl ether 457.2

According to the above composition, aminoethyl ethanolamine methylisobutyl monoketimine 78.8% M
N-methylethanolamine was used instead of the IBK solution, the reaction was performed under the same reaction conditions as in Example 1 except that deionized water was not added and the concentration under reduced pressure was not performed. Dispersion varnish J was used (resin solid content 50%).

[0071] Comparative Example 4 Sho 54-4978 discloses a resin according to preparation 1) Preparation component parts of the quaternizing agent solid content of the 2-ethylhexanol half-blocked 320.0 304 TDI (in MIBK) dimethyl Ethanolamine 87.2 87.2 Lactic acid aqueous solution 117.6 88.2 Ethylene glycol monobutyl ether 39.2 −

According to the above composition, 2-ethylhexanol half-blocked T was prepared at room temperature using a suitable reaction vessel.
DI was added to dimethylethanolamine. The mixture exothermed and was stirred at 80 ° C. for 1 hour. Next, lactic acid was charged, and butyl cellosolve was added to the reaction mixture at 65 ° C.
After stirring for about half an hour, a quaternizing agent was obtained.

2) Preparation Component of Resin Vehicle Parts by Weight Solids Content Epon 829 ¹ 710.0 681.2 Bisphenol A 289.6 289.6 2-Ethylhexanol Half Blocked 406.4 386.1 TDI (in MIBK) 1 ) of quaternizing agent 496.3 421.9 deionized water 71.2 ethylene glycol monobutyl ether 1584.1 - ¹ bisphenol a type epoxy resin, epoxy equivalent 1
93-203, Shell Chemical Company

According to the above composition, EPON829 and bisphenol A were charged into a suitable reaction vessel and heated to 150 to 160 ° C. under a nitrogen atmosphere. An initial exothermic reaction occurred. The reaction mixture was reacted at 150-160 ° C for about 1 hour, then after cooling to 120 ° C, 2-ethylhexanol half blocked TDI was added. 11 reaction mixture
Hold at 0-120 ° C. for about 1 hour, then add butyl cellosolve. Then, the mixture was cooled to 85 to 95 ° C., homogenized, and the quaternizing agent of 1) was added. The reaction mixture was kept at 85 to 85 ° C. until the acid value became 1, to obtain a varnish K for dispersing pigment (resin solid content 50%).

[0075]

[Table 1]

Examples 8 to 14 show the preparation of various pigment dispersion pastes using the pigment dispersion varnishes obtained in Examples 1 to 7 and the preparation of various cationic electrodeposition coating compositions using these pigment pastes.

Example 8 The following mixture of components was dispersed in a sand grind mill,
A pigment dispersion paste pulverized to a particle size of 10 μm or less was prepared.

Ingredients By Weight Pigment Dispersion Paste (Example 1) 30.0 (15.0 Parts Solids) Deionized Water 71.9 50% Lactic Acid 3.5 Carbon Black 1.8 Kaolin 20.0 Lead Silicate 6 0.0 Titanium dioxide 72.2 This pigment-dispersed paste had a total solid content of 56.0%, a resin solid content of 7.3%, and a pigment solid content of 48.7%.

Then, a cationic electrodeposition coating material A was prepared according to the following composition. Ingredients by weight Aqueous dispersion A of the main resin for cationic electrodeposition coating A 1979.2 Pigment paste of this example 513.4 Deionized water 2507.4

A pigment paste was added to an aqueous dispersion A of a main resin for cationic electrodeposition coating composition and mixed uniformly, and deionized water was added to obtain a cationic electrodeposition coating composition A having a solid content of 20.0%. The stability with time of the cationic electrodeposition coating material A obtained by evaluating the 380 mesh screen filterability and the amount of residue after storing for 2 weeks under stirring at 40 ° C. was evaluated.

Then, the obtained electrodeposition coating composition A was electrodeposited on a zinc phosphate-treated cold rolled steel sheet by 20 μm, baked at 160 ° C. for 10 minutes, cut, and then 240 ° C. in 5% NaCl water at 55 ° C. for 240 hours. I put it in. A 2.4 cm wide adhesive tape (manufactured by Nichiban Co., Ltd.) was firmly attached to this sample with a finger, and then the adhesive tape was rapidly peeled off, and the maximum peeling width of the coating film from the steel sheet was measured. The salt water corrosion resistance was evaluated. The evaluation results are shown in Table 2 together with the results obtained in Examples 9 to 14 and Comparative Examples 5 to 9 below.

Example 9 A pigment-dispersed paste was prepared in the same manner as in Example 8 except that the pigment-dispersed varnish of Example 2 was used instead of the pigment-dispersed varnish of Example 1, and cationic electrodeposition was performed using the paste. Paint B was prepared.

Example 10 The pigment dispersion varnish of Example 3 was used in place of the pigment dispersion varnish of Example 1, 72.6 parts of deionized water, 50% lactic acid 2.
Change to 8 parts, water dispersion B of the main resin for cationic electrodeposition coatings
A pigment dispersion liquid paste was prepared in the same manner as in Example 8 except that was used to prepare a cationic electrodeposition coating C using the same.

Example 11 The pigment dispersion varnish of Example 4 was used in place of the pigment dispersion varnish of Example 1, and 72.5 parts of deionized water and 2.9% of 50% lactic acid were used.
A pigment-dispersed paste was prepared in the same manner as in Example 8 except that parts were changed, and a cationic electrodeposition coating D using the same was prepared.

Example 12 The pigment dispersion varnish of Example 5 was used in place of the pigment dispersion varnish of Example 1, and 44.6 parts of the pigment dispersion varnish, 73.5 parts of deionized water, and 5.1 parts of 50% lactic acid were added. Pigment Dispersion Paste (total solids content 56.0)
%, Resin solid content 11.2%, pigment solid content 44.8%), and a cationic electrodeposition coating E using the same was prepared according to the following composition.

Ingredients by weight Aqueous dispersion A of the main resin for cationic electrodeposition coating A 1909.7 Pigment paste of this example 558.0 Deionized water 2532.3

Example 13 The pigment dispersion varnish of Example 6 was used in place of the pigment dispersion varnish of Example 1, and 89.3 parts of the pigment dispersion varnish, 73.4 parts of deionized water and 5.2 parts of 50% lactic acid were added. Pigment Dispersion Paste (total solids content 56.0)
%, Resin solid content 18.7%, pigment solid content 37.3%), and a cationic electrodeposition coating F using the same was prepared according to the following composition.

Ingredients by weight Aqueous dispersion of main resin for cationic electrodeposition coating A 1736.1 Pigment paste of this example 669.6 Deionized water 2594.3

Example 14 The pigment dispersion varnish of Example 7 was used in place of the pigment dispersion varnish of Example 1 except that 30.0 parts of the pigment dispersion varnish, 75.4 parts of deionized water, and 50% lactic acid were not added. A pigment dispersion paste (total solids content: 56.0) was obtained in the same manner as in Example 8 except for the above.
%, Resin solid content 7.3%, pigment solid content 48.7%), and a cationic electrodeposition coating G using the same was prepared.

Example 15 A cationic electrodeposition coating composition H was prepared in the same manner as in Example 8 except that the aqueous dispersion C of the main resin for cationic electrodeposition coating using the pigment dispersion paste of Example 8 was used.

Comparative Examples 5 to 9 show the preparation of various pigment dispersion pastes using the pigment dispersion varnishes of Comparative Examples 1 to 4 and the preparation of various cationic electrodeposition coating compositions using these pigment pastes.

Comparative Example 5 The pigment dispersion varnish of Example 1 was replaced with the pigment dispersion varnish of Comparative Example 1 using 70.9 parts of deionized water and 50% lactic acid 4.5.
A pigment-dispersed paste was prepared in the same manner as in Example 8 except that parts were changed, and a cationic electrodeposition coating material I using the same was prepared.

Comparative Example 6 The pigment-dispersed varnish of Comparative Example 2 was used in place of the pigment-dispersed varnish of Example 1, and 73.9 parts of deionized water and 2.0% of 50% lactic acid were used.
A pigment-dispersed paste was prepared in the same manner as in Example 8 except that the parts were changed, and a cationic electrodeposition coating material J using the same was prepared.

Comparative Example 7 The pigment-dispersed varnish of Example 1 was replaced by the pigment-dispersed varnish of Comparative Example 3, and 71.8 parts of deionized water and 3.6% of 50% lactic acid were used.
A pigment-dispersed paste was prepared in the same manner as in Example 8 except that parts were changed, and a cationic electrodeposition coating K using the same was prepared.

Comparative Example 8 The same as Example 8 except that the pigment-dispersed varnish of Comparative Example 4 was used in place of the pigment-dispersed varnish of Example 1, and 75.4 parts of deionized water and 50% lactic acid were added without compounding. To prepare a pigment-dispersed paste, and a cationic electrodeposition coating L using the same is prepared.
Was prepared.

Comparative Example 9 Ingredients by weight Pigment dispersion varnish A of Example 1 712.5 Glacial acetic acid 27.7 Aqueous dispersion A of the main resin for cationic electrodeposition coating A 989.6 Pigment paste of Example 8 513.4 Deionized water 2756.8

Glacial acetic acid was uniformly mixed with the pigment dispersion varnish A of Example 1 according to the above composition, and then the aqueous dispersion A of the main resin for cationic electrodeposition coating was slowly added and completely dissolved. A pigment paste and deionized water were added to this to obtain a cationic electrodeposition coating L having a solid content of 20.0%.

[0098]

[Table 2] (1) (2) Example No. Storage stability used Salt water resistant Paint solid content Pigment dispersion evaluation result Anticorrosion pigment dispersion resin Varnish weight ratio (mg) (mm) (%) ) Example 8 A 15 2.0 3.8 Example 9 B 9 1.5 3.8 Example 10 C 12 2.5 3.8 Example 11 D 18 1.8 3.8 Example 12 E 25 2.1 6.2 Example 13 F 15 2.9 12.5 Example 14 G 13 2.6 3.8 Example 15 A 28 3.0 3.8 Comparative Example 5 H 1000 or more 3.5 3.3. 8 Comparative Example 6 I 50 3.0 3.8 Comparative Example 7 J 1000 or higher 3.8 3.8 Comparative Example 8 K 35 6.5 3.8 Comparative Example 9 A 11 4.8 39.4 (1) 2 liters of the coating material was stored under stirring at 40 ° C. for 2 weeks, and evaluated by the amount of 380 mesh screen filtration residue. (2) Saltwater corrosion resistance is measured in 240 hours. The maximum peel width is shown.

[0099]

EFFECT OF THE INVENTION A cationic resin capable of providing an electrodeposition coating composition having excellent storage stability and a coating film having excellent corrosion resistance is provided.

Front Page Continuation (72) Inventor Yoshio Kojima 19-17 Ikedanaka-cho, Neyagawa City, Osaka Japan Paint Co., Ltd. (56) References JP-A-52-11228 (JP, A) JP-A-58-18746 (JP) , A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C09D 5 / 44,163 / 00,175 / 04

Claims (5)

(57) [Claims] 1. An electrodeposition coating composition comprising (A) a cationic resin, (B) a low temperature dissociative blocked isocyanate curing agent, and (C) a pigment paste having a pigment dispersed in a pigment dispersion resin. The SP value of the hydrophobic resin before cationization of the pigment dispersion resin is 10.
0 to 11.0 and a primary amino group of 1.6 to 1 in one molecule.
It has 4.0 and each component ratio is A / B / C = 10
88/10 to 50/2 to 50, wherein the hydrophobic resin is an epoxy resin, and the SP value of the hydrophobic epoxy resin is 1.0 to 0 for residues of isocyanate in one molecule. A cationic electrodeposition coating composition, which is adjusted by adding 0.5 to 2.5 of an isocyanate having a molar equivalent of 0.5 to one molecule of an epoxy resin. 2. The cationic electrodeposition coating composition according to claim 1, wherein the primary amino group is introduced by the reaction of a partially ketimine-capped polyamine and an epoxy resin. 3. The cationic electrodeposition coating composition according to claim 1, wherein a part of the primary amino group added to the hydrophobic resin is reacted with an acid anhydride to form an amide group. 4. The cation according to claim 3, which has an average of 1.0 to 3.0 amino groups and an average of 0.6 to 3.0 amide groups in one molecule of the pigment dispersion resin before cationization. Electrodeposition coating composition. 5. The cationic electrodeposition coating composition according to claim 1, wherein the cationic resin of component A is an amine-modified epoxy resin.