JPH0575024B2 - - Google Patents

Description

[Detailed description of the invention]

Background and Problems of the Present Invention Conventionally, it has been known to add minute resin particles (microgel) made of a polymer of internally crosslinked ethylenically unsaturated monomers to electrodeposition paints to obtain a matte coating film. See JP-A-58-93762 and JP-A-56-49766. Adding microgel to electrodeposition paints is effective not only for the purpose of matting, but also for improving coating film performance and throwing power. However, these microgels do not have the charge necessary for electrodeposition, are insoluble in aqueous media, and do not thermally fuse at the baking temperature of the coating film, so they cannot be electrodeposited alone; It must be used in conjunction with a water-based resin that has the necessary charge for electrocoating. However, in this case, the microgel cannot be added in large amounts because it impairs the storage stability of the paint and the workability of electrodeposition due to the above-mentioned properties. Therefore, the present invention provides a new type of cationic gel fine particles with a core/shell structure, in which the core is made of a thermosetting crosslinked resin and the shell is made of an aqueous resin that has a positive charge and hydrophilic groups necessary for electrodeposition. Provided is a method for producing an aqueous dispersion of. Solution The present invention provides (A) a cationic film-forming aqueous resin obtained by modifying an epoxy resin or a partially epoxidized polybutadiene resin with an amine in terms of solid content;
100 parts by weight, and (B) a resin composition containing 10 to 250 parts by weight in terms of solid content of methylolphenols obtained by reacting phenols with formaldehyde, and an aqueous resin composition containing an acid that neutralizes the aqueous resin (A). Provided is a method for producing an aqueous dispersion of cationic gel particles, which comprises emulsifying the present invention in a medium and heating the resulting emulsion at a temperature equal to or higher than the reaction temperature of the methylolphenols. The aqueous dispersion of cationic gel particles of the present invention is
The particles themselves have a positive charge that can be electrodeposited, and the hydrophilic water-based resin forms a shell that covers the insoluble thermosetting cross-linked resin core, so this is added to cationic electrodeposition paints. In this case, the electrodeposition workability and coating performance are not impaired, and the storage stability of the paint is not adversely affected. Preferred Embodiments The cationic film-forming aqueous resin (A) is used as a film-forming resin in the production of cationic electrodeposition paints. They have cationic functional groups such as amino groups that give the resin a positive electrolyte and hydrophilic properties. Various types of such resins are known, and water-based resins that can be used in the present invention include amine-modified epoxy resins and aminated polybutadiene resins. Amine-modified epoxy resin can be produced by reacting a polyglycidyl compound with a primary or secondary amine. A polyglycidyl compound is an epoxy compound having two or more glycidyl groups in the molecule, and is obtained by reacting an aromatic or aliphatic polyhydric alcohol with epichlorohydrin. A specific example is Epotote YD-011 (manufactured by Toto Kasei Co., Ltd.), which is a bisphenol A type.
), aliphatic Denacol EX-212 (manufactured by Nagase Kasei Co., Ltd.) and PG-207 (manufactured by Toto Kasei Co., Ltd.), and phenol novolac type Epotote YDPN-
638 (manufactured by Toto Kasei Co., Ltd.). The primary or secondary amines added to these polyglycidyl compounds include monomethylamine,
Primary amines such as monoethylamine, n-butylamine, monoethanolamine, dimethylamine, diethylamine, diisopropylamine, N
- Secondary amines such as methylethanolamine, N-ethylethanolamine, diethanolamine,
and diketimine obtained by the dehydration reaction of diethylenetriamine and methyl isobutyl ketone. These amines are reacted in approximately equivalent ratios to the epoxy equivalents of the polyglycidyl compound. Aminated polybutadiene resin is (1) a carbon-carbon double bond with a molecular weight of 500 to 5000 and an iodine value of 50 to 500, and 3 to oxirane oxygen atoms.
(2) 30 to 300 mmol per 100 g of the polymer compound having the general formula

[Formula] (In the formula, R ₁ and R ₂ represent a hydrocarbon group having 1 to 20 carbon atoms which may be substituted with a hydroxyl group, or R ₁ and R ₂ represent nitrogen and optionally other heteroatoms. (represents a ring structure containing), and further reacts (3) 0 to 200 mmol of the general formula per 100 g of the polymer compound of (1) above.

[Formula] (In the formula, R ₃ is a hydrogen atom and R ₄ is a hydrogen atom or a methyl group.) A reaction product obtained by reacting unsaturated fatty acids or a mixture thereof containing % by weight or more. For example, liquid butadiene with a molecular weight of 500 to 5000 is treated with peroxide to reduce the oxygen content of oxirane to 3 to 12% by weight.
Partially epoxidized so that 100
It is obtained by reacting 30 to 300 mmol per g of the aforementioned primary or secondary amine and optionally further reacting up to 200 mmol acrylic acid or methacrylic acid per 100 g of liquid polybutadiene. These resins are neutralized with acid and diluted with water to create an aqueous solution or dispersion. Methylolphenols obtained by reacting phenols and formaldehyde in the presence of an alkali catalyst are crosslinking agents that self-crosslink and/or crosslink with the aqueous resin. These are well known as resol type phenolic resin initial condensates, and are manufactured using phenol, p-cresol, pt-butylphenol, p-aminophenol, p-phenylphenol, bisphenol A, etc. as raw materials. . Since the crosslinking agent (B) performs the crosslinking reaction in water, it must be capable of crosslinking at a temperature of 100° C. or lower when the reaction is carried out at normal pressure. However, if the reaction is carried out under pressure in an autoclave, crosslinking agents that react at temperatures above 100° C. can also be used. The aqueous resin (A) and crosslinking agent (B) can contain an organic solvent in order to lower the viscosity and facilitate emulsion formation. Examples of such solvents include ethyl cellosolve, propyl cellosolve, butyl cellosolve, methanol, ethanol, isopropyl alcohol, n-butanol, isobutanol, ethylene glycol dimethyl ether, diacetone alcohol, 4-methoxy-4-methylpentanone-2 , water-miscible organic solvents such as acetone, methyl ethyl ketone, methoxybutanol, dioxane, ethylene glycol monoethyl ether acetate, xylene, toluene, methyl isobutyl ketone, hexane, carbon tetrachloride, 2-ethylhexanol, isophorone, cyclohexane, benzene, etc. water-immiscible organic solvents. The aqueous resin (A) and crosslinking agent (B) can contain a catalyst such as dinonylnaphthalenesulfonic acid, dinonylnaphthalene disulfonic acid, etc. to promote the reaction of the crosslinking agent. In order to prepare an emulsion by emulsifying a resin composition containing an aqueous resin (A) and a crosslinking agent (B) in an aqueous resin medium, at least one of the amino groups in the aqueous resin (A) must be
What is necessary is to neutralize 20% by weight with an acid, add the crosslinking agent (B) and an aqueous resin medium, and emulsify it. Water-based resin (A) and crosslinking agent (B)
The ratio is per 100 parts by weight of the former in terms of solid content,
The latter is 10 to 250 parts by weight. Preferred acids for neutralizing the aqueous resin (A) include acetic acid, propionic acid, and lactic acid. The aqueous tree medium is water and can contain surfactants to promote emulsification. Examples of nonionic surfactants include polyethylene glycol alkyl phenyl ether, polyethylene glycol alkyl ether, polyoxyalkylene alkyl ether, polyethylene glycol sorbitan monostearate, polypropylene glycol polyethylene glycol ether, and the like. Examples of cationic surfactants include lauryltrimethylammonium chloride, distearyldimethylammonium chloride, alkylpicolinium chloride, and the like. It is desirable to remove the solvent in the emulsion by azeotropic distillation or the like after preparing the emulsion and before heating it. This accelerates the crosslinking reaction. Depending on the reaction temperature of the crosslinking agent (B), the emulsion thus obtained can be heated at a temperature above the reaction temperature under normal pressure or increased pressure to form cationic gel particles with the desired core/shell structure. An aqueous dispersion is obtained. The core/shell type emulsion of the present invention has good thermal stability because it is stably dispersed in water due to the repulsive force of charges of the same sign, and therefore, the thermal crosslinking reaction of the crosslinking agent (B) is carried out in the emulsion form. proceed. Such a crosslinking reaction in the form of an emulsion can be confirmed by adding a large amount of a resin-dissolving solvent, such as tetrahydrofuran, to the emulsion before heating. If it is not crosslinked, the emulsion will dissolve transparently in the solvent; if it is crosslinked, it will be insoluble and the solvent will become cloudy. In addition, the aqueous dispersion of cationic gel particles was air-dried,
After drying under reduced pressure, the particles can be observed under an electron microscope. The aqueous dispersion of cationic gel particles obtained by the present invention can be added to known cationic electrodeposition paints for the purpose of matting, improving the performance of electrodeposition coatings, and the like. In that case, even if a relatively large amount is added, electrodeposition workability, coating film performance, storage stability, etc. will not deteriorate. The above dispersion can also be added to general aqueous coating compositions for the same purpose. Production examples and examples of the present invention are shown below. Parts and percentages herein are by weight. Production example 1 Aminated polybutadiene A Nisseki polybutadiene B-2000 (number average molecular weight
2000, 1,2 bonds (65%) was epoxidized using peracetic acid to produce epoxidized polybutadiene with an oxirane oxygen content of 6.4%. After charging 1000 g of this epoxidized polybutadiene and 354 g of ethyl cellosolve into two autoclaves, 62.1 g of dimethylamine was added, and the mixture was heated to 150°C.
The reaction was carried out for 5 hours. Unreacted amine was distilled off to produce an aminated polybutadiene resin solution. The amine value of this product was 120 mmol/100 g (solid content). Non-volatile content 75% Production example 2 Aminated polybutadiene B Nisseki polybutadiene B-2000 (number average molecular weight
2000, 1,2 bonds (65%) was epoxidized using peracetic acid to produce epoxidized polybutadiene with an oxirane oxygen content of 6.4%. After charging 1000 g of this epoxidized polybutadiene and 354 g of ethyl cellosolve into two autoclaves, 62.1 g of dimethylamine was added, and the mixture was heated to 150°C.
The reaction was carried out for 5 hours. After distilling off the unreacted amine, the mixture was cooled to 120°C, a mixture of 79.3 g of acrylic acid, 7.6 g of hydroquinone and 26.4 g of ethyl cellosolve was added, and the mixture was further reacted at 120°C for 3 hours and 45 minutes. The amine value of this product is 85.2 mmol/100g.
The acid value was 10.0 mmol/100 g, and the solids concentration was 75.4%. Production example 3 Aminated epoxy resin Solid content weight part (%) Epotote YD-012 *2) 700 700 Butyl cellosolve 227 Diethylamine 73 *2) 700 parts of epoxy resin Epotote YD-012 manufactured by Toto Kasei Co., Ltd. and 227 parts of butyl cellosolve. 2.Pour into an autoclave and dissolve. 73 parts of dibutylamine was charged, the temperature was raised to 100°C, and the temperature was kept for 90 minutes to react. Unreacted amine was distilled off to produce an aminated epoxy resin solution. The amine value of this product was 128 mmol/100 g (solid content). Non-volatile content 70.5% Example 1 Resin emulsion A Solid content weight part (%) Aminated polybutadiene resin A 100 75 Tamanol 722 *1) 33.3 25 Glacial acetic acid 2.8 Deionized water 363.9 *1) Resol manufactured by Arakawa Chemical Co., Ltd. type phenolic resin To 100 parts of the aminated polybutadiene of Production Example 1, add 33.3 parts of Tamanol 722 and further 2.8 parts of glacial acetic acid,
Stir thoroughly. 363.9 parts of deionized water was added to this and emulsified to obtain resin emulsion A. When a portion of it was added to 100 times the amount of tetrahydrofuran, it dissolved transparently. The solvent was removed under reduced pressure while adding deionized water, and then resin emulsion A was kept at 95° C. for 6 hours and cooled to obtain a cationic gel particle dispersion. This product did not dissolve transparently in tetrahydrofuran, but became cloudy. Next, a tin plate was dipped in a gel particle dispersion containing 10% nonvolatile content, air-dried, and dried under reduced pressure at room temperature. When observed under an electron microscope, fine particles with a particle size of 100 nm or less were observed. Example 1 Resin emulsion B Solid content weight part (%) Aminated polybutadiene resin B 100 75 Tamanol 722 *1) 33.3 25 Glacial acetic acid 2.8 Deionized water 363.9 *1) Manufactured by Arakawa Chemical Co., Ltd., resol type phenolic resin to 100 parts of the aminated polybutadiene of Example 1;
Add 33.3 parts of Tamanol 722 and 2.8 parts of glacial acetic acid, and stir thoroughly. 363.9 parts of deionized water was added to this and emulsified to obtain resin emulsion B. When a portion of it was added to 100 times the amount of tetrahydrofuran, it dissolved transparently. The solvent was removed under reduced pressure while adding deionized water, and then resin emulsion B was kept at 95° C. for 6 hours and cooled to obtain a cationic gel particle dispersion. This product did not dissolve transparently in tetrahydrofuran, but became cloudy. Next, a tin plate was dipped in a gel particle dispersion containing 10% nonvolatile content, air-dried, and dried under reduced pressure at room temperature. When observed under an electron microscope, fine particles with a particle size of 100 nm or less were observed. Example 3 Resin emulsion C Solid content weight part (%) Aminated epoxy resin 107 75 Tamanol 722 *1) 33.3 25 Glacial acetic acid 2.6 Deionized water 357.1 *1) Manufactured by Arakawa Chemical Co., Ltd., resol type phenolic resin Production example 33.3 parts of Tamanol 722 and 2.6 parts of glacial acetic acid were added to 107 parts of the aminated epoxy resin No. 3, and the mixture was thoroughly stirred. 357.1 parts of deionized water was added to this and emulsified to obtain resin emulsion C. When a portion of it was added to 100 times the amount of tetrahydrofuran, it dissolved transparently. The solvent was removed under reduced pressure while adding deionized water, and then the resin emulsion C was kept at 55° C. for 7 days and cooled to obtain a cationic gel particle dispersion. This product did not dissolve transparently in tetrahydrofuran and became cloudy. Next, a tin plate was dipped in a gel particle dispersion containing 10% nonvolatile content, air-dried, and dried under reduced pressure at room temperature. When observed under an electron microscope, fine particles with a particle size of 100 nm or less were observed. Example 4 Resin emulsion D In Example 1, resin emulsion A was heated to 95°C.
Instead of keeping warm for 6 hours, autoclave
The mixture was kept at 110° C. for 5 hours and cooled to obtain a cationic gel particle dispersion. This product did not dissolve transparently in tetrahydrofuran, but became cloudy. Next, a tin plate was dipped in a gel particle dispersion containing 10% nonvolatile content, air-dried, and dried under reduced pressure at room temperature. When observed under an electron microscope, fine particles with a particle size of 100 nm or less were observed.

Claims (1)

[Scope of Claims] 1 (A) (i) Primary or secondary polyglycidyl compound
An amine-modified epoxy resin obtained by adding a secondary amine, or (ii) a partially epoxidized polybutadiene polymer compound obtained by adding a secondary amine and optionally further reacting with (meth)acrylic acid or unsaturated fatty acid. 100 parts by weight of a cationic film-forming aqueous resin selected from aminated polybutadiene resins, and (B) 10 to 250 parts by weight of methylolphenols obtained by reacting phenols with formaldehyde. emulsifying the resin composition containing the resin composition in an aqueous medium containing an acid that neutralizes the aqueous resin (A),
A method for producing an aqueous dispersion of cationic gel particles, which comprises heating the resulting emulsion at a temperature equal to or higher than the reaction temperature of the methylolphenol. 2. The method for producing an aqueous cationic gel particle dispersion according to item 1, wherein the emulsion is heated under pressure. 3. The method for producing an aqueous cationic gel particle dispersion according to item 1 or 2, wherein the emulsion contains an organic solvent and includes a step of removing the organic solvent before the heating. 4. Items 1 to 3, wherein the aqueous resin (A) is an amine-modified epoxy resin obtained by adding a primary or secondary amine to a bisphenol, aliphatic, or phenol novolak epoxy resin. Any method for producing an aqueous dispersion of cationic gel particles. 5 The aqueous resin (A) has (1) a carbon-carbon double bond with a molecular weight of 500 to 5000 and an iodine value of 50 to 500 and 3 to oxirane oxygen atoms;
(2) 30 to 300 mmol per 100 g of the polymer compound having 12% by weight of the general formula [Formula] (wherein R ₁ and R ₂ may be substituted with a hydroxyl group) (represents a hydrocarbon group having 1 to 20 carbon atoms, or R ₁ and R ₂ represent a ring structure containing nitrogen and optionally other heteroatoms), and further (3) 0 to 200 mmol per 100 g of the polymer compound of (1) above, an α,β amorphous compound represented by the general formula [formula] (wherein R ₃ is a hydrogen atom and R ₄ is a hydrogen atom or a methyl group). Any of Items 1 to 3, which is a reaction product obtained by reacting a saturated carboxylic acid, an unsaturated fatty acid having a molecular weight of 100 to 350 and containing 10% by weight or more of carbon-carbon conjugated double bonds, or a mixture thereof. A method for producing an aqueous dispersion of cationic gel particles as described in .