JP2005162916A - Aqueous resin particle and cation electrodeposition coating material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide aqueous resin particles in which a repelling-preventing property can be compatible with smoothness of coated film by adding to a cation electrodeposition coating. <P>SOLUTION: The aqueous resin particles are obtained by carrying out emulsion polymerization of a monomer mixture containing α, β-ethylenically unsaturated monomer having an alkoxysilyl group by using a resin having an ammonium-based group and obtained by adding a tertiary amine compound and an organic acid to a resin having an epoxy group and quaternalizing the resin as a dispersant. The cation electrodeposition coating comprises the aqueous resin particles in an amount of 3-20 mass% based on solid content of a coating resin. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to aqueous resin particles and a cationic electrodeposition coating composition containing the same.

  Cationic electrodeposition coatings are widely applied to automobile bodies because they exhibit high antirust properties. The formation of this cationic electrodeposition coating film is carried out by depositing an uncured coating film by energizing with the object immersed in the paint bath as the cathode and the counter electrode as the anode, and baking and curing it.

  In this cationic electrodeposition coating, it is well known that a coating film defect called repelling occurs. This repellency is thought to occur when various causative substances are mixed in the uncured coating film. Especially, oil scattered from the joints of the car body causes bumping during bake hardening. A dent may be formed on the surface of the coating film. Since removal of the causative substance is practically difficult, it is necessary to prevent repellency on the paint side.For example, if the flowability of the paint film during baking is kept low, the smoothness of the paint film is impaired. Therefore, it is common to use an additive to prevent repellency.

On the other hand, cross-linked particles are added to the electrodeposition paint for the purpose of achieving both the antirust property of the edge portion and the appearance of the coating film. As such an example, an epoxy resin amine adduct containing a hydrolyzable alkoxysilane group is dispersed in water and crosslinked in the particles (for example, see Patent Document 1) or an acrylic resin having an ammonium group as an emulsifier. Crosslinked resin particles obtained by emulsion polymerization of poly (meth) acrylate (for example, see Patent Document 2) are known. Although the effect of preventing repellency can be expected by the addition of these cross-linked particles, the cross-linked particles do not have fluidity, and therefore there is a problem that the smoothness of the coating film is impaired when the addition amount is increased. In addition, even if non-crosslinked particles that are ordinary emulsions are added, the effect of preventing repellency cannot be obtained.
JP-A-6-16818 (Claim 1) JP 2002-212488 A (Claim 1)

  An object of the present invention is to provide water-based resin particles capable of achieving both repellency prevention properties and coating film smoothness by being added to a cationic electrodeposition coating.

  The aqueous resin particles of the present invention are α, β- having an alkoxysilyl group, using a resin having an ammonium group, which is quaternized by adding a tertiary amine compound and an organic acid to a resin having an epoxy group, as a dispersant. It is obtained by emulsion polymerization of a monomer mixture containing an ethylenically unsaturated monomer. Here, the solid content mass ratio between the resin having an ammonium group and the monomer mixture may be 5/95 to 20/80, and the α, β-ethylene having the alkoxysilyl group in the monomer mixture is present. The proportion of the unsaturated monomer may be 5 to 35% by mass. The weight average molecular weight of the aqueous resin particles of the present invention may be 6000 to 12000, and the glass transition temperature of the monomer mixture may be 50 to 100 ° C. Furthermore, the aqueous resin particles of the present invention may further contain an alcohol having 1 to 18 carbon atoms, and the content thereof is 2 to 5 times the molar amount of the α, β-ethylenically unsaturated monomer having an alkoxysilyl group. It may be.

  The method for producing water-based resin particles of the present invention is obtained by adding a tertiary amine compound and an organic acid to a resin having an epoxy group and quaternizing the resin having an ammonium group as a dispersing agent. It is characterized by emulsion polymerization of a monomer mixture containing a β-ethylenically unsaturated monomer.

  The aqueous resin particles obtained by this production method are also one aspect of the present invention.

  The cationic electrodeposition coating composition of the present invention contains 3 to 20% by mass of the above aqueous resin particles in the solid content of the coating resin. Here, the binder component of the cationic electrodeposition coating composition may be an epoxy resin in which an epoxy group is amine-modified and / or an acrylic resin, and may contain the resin having an ammonium group as the binder component.

  By adding the aqueous resin particles of the present invention to the cationic electrodeposition coating material, it is possible to achieve both repellency prevention properties and smoothness of the coating film. This is because the water-based resin particles of the present invention are non-crosslinked type, and in the initial stage of baking, the particles are melted to give the coating film smoothness and further baked to condense alkoxysilyl groups. As a result, it is considered that oil repellency can be prevented at the same time because the hardness of the surface is increased.

  In addition, by setting the solubility parameter value of the monomer mixture as a raw material within a certain range, the film surface migration of particles can be enhanced. Moreover, the stability in a cationic electrodeposition coating composition can be improved by setting the glass transition temperature of a monomer mixture high. Moreover, flow property can be improved by setting the molecular weight of the resin particles low.

  The aqueous resin particles of the present invention are aqueous resin particles obtained by emulsion polymerization of a monomer mixture using a resin having an ammonium group as a dispersant.

  The resin having an ammonium group preferably has 2 to 15 ammonium groups per molecule. If the number of ammonium groups exceeds 15 per molecule, the water resistance of the coating film obtained when used in a cationic electrodeposition paint may be lowered. May not be obtained.

  As the resin having an ammonium group, a resin obtained by adding a tertiary amine compound and an organic acid to a resin having an epoxy group to be quaternized is used. When a resin having a tertiary amino group quaternized with an organic acid is used, there is a problem in the storage stability of the resulting aqueous resin particles.

  Examples of the resin having an epoxy group include an epoxy resin and an acrylic resin. The epoxy resin is not particularly limited, and a polyphenol polyglycidyl ether type epoxy resin which is a reaction product of a polycyclic phenol compound such as bisphenol A, bisphenol F, bisphenol S, phenol novolak, cresol novolak and epichlorohydrin is used. It is common. In addition, those obtained by extending the chain of these exemplified epoxy resins with a bifunctional polyester polyol, polyether polyol, bisphenol, dibasic carboxylic acid or the like can also be used. When an epoxy resin is used as the resin having an epoxy group, the epoxy equivalent is preferably 600 to 1200.

  On the other hand, the acrylic resin is obtained by copolymerizing an α, β-ethylenically unsaturated monomer having an epoxy group such as glycidyl (meth) acrylate with another α, β-ethylenically unsaturated monomer. An acrylic resin having an epoxy group can be used. In the above quaternization method, the epoxy group is ring-opened with a tertiary amine to form an ammonium group. Therefore, the α, β-ethylenically unsaturated group having an epoxy group is selected according to the number of desirable ammonium groups described above. The amount of monomer can be determined. As the other α, β-ethylenically unsaturated monomers, among the general α, β-ethylenically unsaturated monomers described in the description of the production of aqueous resin particles described later, those that do not react with an epoxy group Can be used.

Moreover, it is preferable that the solubility parameter of the copolymerization monomer used in order to obtain the acrylic resin which has this epoxy group is 9-12. If the solubility parameter of the monomer exceeds 12, the coating appearance and rust prevention properties of the coating film obtained when used for the cationic electrodeposition coating are lowered, and if it is less than 9, the problem of poor adhesion with the top coat occurs. The solubility parameter is also called SP (solubility parameter) among those skilled in the art, and is a scale indicating the degree of hydrophilicity or hydrophobicity of the resin, and also determines the compatibility between the resins. It is also an important measure to do. This value is numerically quantified based on, for example, the following turbidity measuring method.
Reference: K.K. W. Suh, D .; H. Clarke J. et al. Polymer. Sci. , A-1, 5, 1671 (1967)

  This acrylic resin having an epoxy group can be carried out by a conventional method such as solution polymerization of the above monomer using a well-known initiator. The number average molecular weight of the acrylic resin having an epoxy group thus obtained is preferably 5,000 to 20,000. If the number average molecular weight exceeds 20000, the viscosity is too high to be used as an emulsifier, and if it is less than 5000, the intended aqueous resin particles may not be obtained.

The quaternization can be performed by previously mixing a tertiary amine compound and an organic acid and adding this mixture as a quaternizing agent to a resin having an epoxy group.
Here, as the tertiary amine compound for introducing an ammonium group into the resin, various compounds such as trimethylamine, triethylamine, tributylamine, trioctylamine, dimethylethanolamine, and methyldiethanolamine can be used. The amount of the tertiary amine compound can be determined according to the amount of ammonium group to be introduced.

  On the other hand, examples of the organic acid include formic acid, acetic acid, lactic acid, propionic acid, boric acid, butyric acid, dimethylolpropionic acid, hydrochloric acid, sulfuric acid, phosphoric acid, N-acetylglycine, and N-acetyl-β-alanine. However, lactic acid, acetic acid, and dimethylolpropionic acid are preferable from the viewpoint of stability during emulsification.

  In this quaternization, the amount of the epoxy group, tertiary amine compound, and organic acid in the acrylic resin having an epoxy group is preferably 1/1/1 to 1/1/2 in molar ratio. The quaternization reaction is generally performed over 2 to 10 hours, and may be heated to 60 to 100 ° C. as necessary.

  The aqueous resin particles of the present invention are obtained by emulsion polymerization of a monomer mixture containing an α, β-ethylenically unsaturated monomer having an alkoxysilyl group using the resin having an ammonium group as a dispersant.

  As the α, β-ethylenically unsaturated monomer having an alkoxysilyl group, γ-methacryloxypropyltrimethoxysilane, γ-acryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-acryloxypropyldimethyl Methoxysilane, γ-methacryloxypropyldimethylmethoxysilane, γ-acryloxypropyltriethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-acryloxypropylmethyldiethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-acryloxypropyldimethylethoxysilane, γ-methacryloxypropyldimethylethoxysilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyltriethoxysilane Emissions, vinyl methyl diethoxy silane, trimethoxy silyl styrene, dimethoxy methyl silyl styrene, triethoxysilyl styrene, etc. diethoxymethylsilyl styrene. Among these compounds, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, which is highly polymerizable with other α, β-ethylenically unsaturated monomers and easily industrially available, γ-methacryloxypropylmethyldimethoxysilane and γ-methacryloxypropylmethyldiethoxysilane are more preferable.

  The monomer mixture contains a general α, β-ethylenically unsaturated monomer in addition to the α, β-ethylenically unsaturated monomer having an alkoxysilyl group. As this general α, β-ethylenically unsaturated monomer, for example, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, allyl alcohol, methacryl alcohol, (meth) Mention may be made of α, β-ethylenically unsaturated monomers having a hydroxyl group such as adducts of hydroxyethyl acrylate and ε-caprolactone.

  On the other hand, (meth) acrylic acid ester (for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate) as an α, β-ethylenically unsaturated monomer having no reactive functional group , (Isopropyl) (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl methacrylate, phenyl acrylate, (Meth) acrylic acid isobornyl, methacrylic acid cyclohexyl, (meth) acrylic acid t-butylcyclohexyl, (meth) acrylic acid dicyclopentadienyl, (meth) acrylic acid dihydrodicyclopentadienyl, etc.), polymerizable aromatic Compound (for example, styrene, α-methylstyrene, vinyl ketone, t-butyl) Styrene, parachlorostyrene, vinyl naphthalene, etc.), polymerizable nitriles (eg, acrylonitrile, methacrylonitrile, etc.), α-olefins (eg, ethylene, propylene, etc.), vinyl esters (eg, vinyl acetate, vinyl propionate, etc.) , Dienes (for example, butadiene, isoprene, etc.), polymerizable aromatic compounds, polymerizable nitriles, α-olefins, vinyl esters, and dienes.

The proportion of the α, β-ethylenically unsaturated monomer having the alkoxysilyl group in the monomer mixture can be 5 to 35% by mass. If it is less than 5% by mass, the repellency is not sufficient, and if it exceeds 35% by mass, a problem may occur in storage stability.
Moreover, it is preferable that the glass transition temperature as said monomer mixture is 50-100 degreeC. If it is less than 50 ° C., there is a problem in storage stability, and if it exceeds 100 ° C., the repellency prevention property may be insufficient. A preferred lower limit is 60 ° C and an upper limit is 95 ° C. On the other hand, the solubility parameter of the monomer mixture is preferably 9-12. If it is less than 9, there is a possibility that the problem of poor adhesion with the top coat may occur, and if it exceeds 12, the coating appearance and rust prevention properties of the coating film obtained when used in a cationic electrodeposition paint may be lowered.

  Furthermore, the monomer mixture may contain an alcohol having 4 to 18 carbon atoms. By containing an alcohol having 6 to 18 carbon atoms, the storage stability of the aqueous resin particles of the present invention can be improved. Examples of the alcohol having 6 to 18 carbon atoms include linear aliphatic alcohols (for example, hexyl alcohol, octyl alcohol, lauryl alcohol, stearyl alcohol), branched aliphatic alcohols (for example, 2-ethylhexyl alcohol, cyclohexyl alcohol). Polyethylene glycol ethers (for example, ethylene glycol monoalkyl ethers, diethylene glycol monoalkyl ethers, triethylene glycol monoalkyl ethers, polyethylene glycol phenyl ether, etc.), polypropylene glycol ethers (for example, propylene glycol monoalkyl, etc.) Ethers, dipropylene glycol monoalkyl ethers, tripropylene glycol monoalkyl ethers, polypropylene Such as glycol phenyl ether) aromatic alcohols (e.g., phenol, cresol, etc.,) and the like. When the monomer mixture contains an alcohol having 6 to 18 carbon atoms, the content thereof can be 2 to 5 times the molar amount of the α, β-ethylenically unsaturated monomer having an alkoxysilyl group. If the amount is less than 2 times the molar amount, it is difficult to improve the storage stability. If the amount exceeds 5 times the molar amount, the repellency prevention property may be insufficient. The aqueous resin particles of the present invention thus obtained substantially contain a predetermined amount of alcohol having 6 to 18 carbon atoms. However, alcohols that are not included in the monomer mixture, such as alcohols used as solvents in the production of acrylic resins having an ammonium group, are not included in the alcohols having 6 to 18 carbon atoms.

  The emulsion polymerization for obtaining the aqueous resin particles of the present invention can be carried out by a generally well-known method. Specifically, the above-mentioned monomer mixture and polymerization initiator are added to the aqueous medium containing an organic solvent such as water or, if necessary, alcohol, as a dispersant, and the mixture is heated and stirred. Can be performed by dripping. A monomer mixture emulsified in advance using a dispersing agent and water may be similarly dropped.

  Preferably, the previous dispersant is dissolved in an aqueous medium, and the initiator is added dropwise under heating and stirring, and then a part of the monomer mixture is first added dropwise, and then pre-emulsified using the dispersant and water. A method of dropping the remaining monomer mixture can be employed. By adopting this method, variation from the target particle diameter is reduced, and preferable aqueous resin particles can be obtained.

  Examples of the polymerization initiator that can be suitably used here include azo oily compounds (for example, azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2 -(2-imidazolin-2-yl) propane) and 2,2′-azobis (2,4-dimethylvaleronitrile)) and aqueous compounds (for example, anionic 4,4′-azobis (4-cyanoacetate) Herbic acid), 2,2-azobis (N- (2-carboxyethyl) -2-methylpropionamidine) and cationic 2,2'-azobis (2-methylpropionamidine)); and redox oily peroxidation Products (for example, benzoyl peroxide, parachlorobenzoyl peroxide, lauroyl peroxide and t-butyl perbenzoate) And aqueous peroxides (e.g., such as potassium persulfate and ammonium persulfate) and the like.

  In addition to the above-mentioned dispersants, those commonly used by those skilled in the art and reactive emulsifiers such as Antox MS-60 (manufactured by Nippon Emulsifier Co., Ltd.), Eleminol JS-2 (manufactured by Sanyo Kasei Kogyo Co., Ltd.) ), Adekaria soap NE-20 (Asahi Denka Co., Ltd.) and Aqualon HS-10 (Daiichi Kogyo Seiyaku Co., Ltd.) may be used in combination.

  Here, the solid content mass ratio between the resin having an ammonium group as a dispersant and the monomer mixture may be 5/95 to 20/80. If it is less than 5/95, it may agglomerate and generate flaws, and if it exceeds 20/80, the repellency prevention property may not be maintained.

  In order to adjust the molecular weight, a mercaptan such as lauryl mercaptan and a chain transfer agent such as α-methylstyrene dimer may be used as necessary.

  The reaction temperature is determined by the initiator, and for example, it is preferably 60 to 90 ° C. for an azo initiator and 30 to 70 ° C. for a redox system. In general, the reaction time is 1 to 8 hours. The amount of the initiator relative to the total amount of the α, β-ethylenically unsaturated monomer mixture is generally 0.1 to 5% by mass, preferably 0.2 to 2% by mass.

  The average particle diameter of the aqueous resin particles of the present invention thus obtained is preferably in the range of 0.05 to 0.30 μm. When the particle diameter is less than 0.05 μm, the effect of improving workability is small, and when it exceeds 0.30 μm, the appearance of the obtained coating film may be deteriorated. The particle diameter can be adjusted, for example, by adjusting the composition of the monomer mixture and the emulsion polymerization conditions.

  Moreover, it is preferable that the mass mean molecular weight of the water-based resin particle of this invention is 6000-12000. If it is less than 6000, the repellency is poor, and if it exceeds 12,000, the smoothness of the coating film may be lowered.

  The method for producing water-based resin particles of the present invention is obtained by adding a tertiary amine compound and an organic acid to a resin having an epoxy group and quaternizing the resin having an ammonium group as a dispersing agent. It is characterized by emulsion polymerization of a monomer mixture containing a β-ethylenically unsaturated monomer. About this content, the description about the aqueous resin particle | grains of the above-mentioned this invention is applied as it is.

  The cationic electrodeposition coating composition of the present invention contains 3 to 20% by mass of the above aqueous resin particles based on the solid content of the coating resin. If it is less than 3% by mass, the effect of preventing repellency cannot be obtained, and if it exceeds 20% by mass, the smoothness of the coating film may be lowered. The cationic electrodeposition coating composition is preferably an epoxy resin and / or an acrylic resin whose binder component is an amine-modified epoxy group. Moreover, the binder component may contain a resin having the above ammonium group.

  The cationic electrodeposition coating composition of the present invention can be obtained by adding the predetermined amount of aqueous resin particles to a normal cationic electrodeposition coating composition. Examples of the normal cationic electrodeposition coating composition include those in which the epoxy group is amine-modified, an epoxy resin and / or an acrylic resin as a binder resin, and a blocked isocyanate as a curing agent.

  The production example for obtaining the material used for the Example of this invention below is shown. In the following production examples and examples, “part”, “%”, and ratio are based on mass.

Production Example 1 Production of Acrylic Resin Having Ammonium Group 120 parts of butyl cellosolve was placed in a reaction vessel, and heated and stirred at 120 ° C. An initiator solution in which 2 parts of t-butylperoxy-2-ethylhexanoate and 10 parts of butyl cellosolve were mixed, 19 parts of glycidyl methacrylate, 60 parts of 2-ethylhexyl methacrylate, 20 parts of 2-hydroxyethyl methacrylate and A monomer consisting of 1 part of n-butyl methacrylate and having a solubility parameter of 10.1 was added dropwise simultaneously over 3 hours. After aging for 30 minutes, a solution in which 0.5 part of t-butylperoxy-2-ethylhexanoate and 5 parts of butyl cellosolve were added dropwise in 30 minutes, and after aging for 2 hours, the mixture was cooled. . The number average molecular weight of the acrylic resin having an epoxy group determined by GPC in terms of polystyrene was 8500, and the weight average molecular weight was 17,900. 7 parts of dimethylaminoethanol and 15 parts of 50% lactic acid aqueous solution were added thereto, and quaternization was performed by heating and stirring at 80 ° C. When the acid value became 1 or less and the viscosity increase stopped, heating was stopped to obtain an acrylic resin having an ammonium group. The number of ammonium groups per molecule of the acrylic resin having ammonium groups was 8.2.

Production Example 2 Preparation of Pigment Dispersion Paste 222.0 parts of isophorone diisocyanate was added to a reaction vessel, diluted with 39.1 parts of methyl isobutyl ketone, and then 0.2 part of dibutyltin dilaurate was added. After raising the temperature to 50 ° C., 131.5 parts of 2-ethylhexyl alcohol was added dropwise over 2 hours. By appropriately cooling and maintaining the reaction temperature at 50 ° C., a half-blocked isocyanate having a solid content of 90% was obtained.

  Next, 351.6 parts of Epon 828 (epoxy resin manufactured by Shell Chemical Co., Ltd., epoxy equivalent 190) and 99.2 parts of bisphenol A were charged in another reaction vessel and heated to 130 ° C. in a nitrogen atmosphere. To this, 1.41 parts of benzyldimethylamine was added and reacted at 170 ° C. for about 1 hour to obtain a bisphenol A type epoxy resin having an epoxy equivalent of 450. After the reaction solution was cooled to 140 ° C., 218.3 parts of the previously obtained half-blocked isocyanate was added and kept at 140 ° C. for 1 hour.

  After diluting by adding 172.3 parts of dipropylene glycol monobutyl ether, the reaction solution was cooled to 100 ° C. and SHP-100 (1- (2-hydroxyethylthio) -2-propanol, Sanyo Chemical Co., Ltd.) 408.0 parts (solid content 136.0 parts), dimethylolpropionic acid 134.0 parts and deionized water 144.0 parts were added and reacted at 70-75 ° C. until the acid value was 3.0 or less. By this reaction, a sulfonium group-modified epoxy resin having a tertiary sulfoniumation rate of 70.6% was obtained. This was diluted with 324.8 parts of dipropylene glycol monobutyl ether and 1204.8 parts of deionized water to obtain a sulfonium group-containing pigment dispersion resin having a resin solid content of 30%.

  180 parts of the sulfonium group-containing pigment dispersion resin thus obtained, 9 parts of MA-100 (carbon black, manufactured by Mitsubishi Chemical Corporation), 76 parts of barium sulfate B-30 (manufactured by Sakai Chemical Industry Co., Ltd.), KF Bowsei PM -303W (aluminum zinc zinc phosphomolybdate inorganic pigment, manufactured by Kikuchi Color Co., Ltd.) 15 parts, 8 parts of dibutyltin oxide and 36 parts of ion-exchanged water are mixed and pulverized to a particle size of 10 μm or less with a sand grind mill to prepare a pigment dispersion paste. did.

Production Example 3 Production of base resin In a reaction vessel, 54.0 parts of 2,4- / 2,6-tolylene diisocyanate (weight ratio = 8/2), 136 parts of methyl isobutyl ketone (hereinafter referred to as MIBK) and dibutyltin dilaurate 0.5 part was added. When 10.9 parts of methanol was added thereto at room temperature, the temperature in the system was raised to 60 ° C. due to heat generation. Thereafter, the reaction was continued for 30 minutes, and then 54 parts of ethylene glycol mono-2-ethylhexyl ether was added dropwise over 1 hour. The reaction was carried out mainly in the range of 60 to 65 ° C. and continued until the isocyanate group disappeared while measuring the IR spectrum.

  Next, 285 parts of epoxy resin having an epoxy equivalent of 950 synthesized from bisphenol F and epichlorohydrin was added, and the temperature was raised to 125 ° C. Thereafter, 0.62 part of benzyldimethylamine was further added, and the reaction was carried out while distilling off by-produced methanol using a decanter until an epoxy equivalent of 1120 was reached. Thereafter, the mixture was cooled, 29.1 parts of diethanolamine, 21.5 parts of methylethanolamine and 32.9 parts of a ketimine product of aminoethylethanolamine (79 wt% MIBK solution) were added and reacted at 110 ° C. for 2 hours. Then, it diluted with MIBK until it became non-volatile matter 80%, and the base resin containing an oxazolidone ring was obtained.

Production Example 4 Production of Blocked Isocyanate Curing Agent In a reaction vessel, 222 parts of 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate and 55.5 parts of MIBK were heated to 70 ° C. After the contents were uniformly dissolved, 17.4 parts of methyl ethyl ketoxime was added dropwise over 2 hours. After completion of the dropwise addition, the temperature was maintained at 70 ° C. and reacted until the isocyanate group disappeared by IR analysis to obtain a blocked isocyanate curing agent.

Example 1 Production of Aqueous Resin Particles Part 1
To the reaction vessel, 20 parts of an acrylic resin having an ammonium group produced in Production Example 1 and 270 parts of deionized water were added and heated and stirred at 75 ° C. To this, 1.5 parts of 2,2′-azobis (2- (2-imidazolin-2-yl) propane)) 100% neutralized aqueous solution of acetic acid was added dropwise over 5 minutes. After aging for 5 minutes, 30 parts of methyl methacrylate was added dropwise over 5 minutes. After aging for 5 minutes, 170 parts of methyl methacrylate, 40 parts of styrene, 30 parts of n-butyl methacrylate, γ-methacryloxy were added to a solution obtained by mixing 70 parts of the acrylic resin having an ammonium group and 250 parts of deionized water. A pre-emulsion obtained by adding and stirring a monomer mixture containing an α, β-ethylenically unsaturated monomer having an alkoxysilyl group consisting of 30 parts of propyltriethoxysilane and 1 part of lauryl mercaptan was added dropwise over 40 minutes. . After aging for 60 minutes, the mixture was cooled to obtain an aqueous resin particle dispersion. The obtained aqueous resin particle dispersion had a non-volatile content of 38%, a pH of 5.0, and an average particle size measured by a laser light scattering method of 90 nm.

Example 2 Production of water-based resin particles 2
To the reaction vessel, 20 parts of an acrylic resin having an ammonium group produced in Production Example 1 and 270 parts of deionized water were added and heated and stirred at 75 ° C. Thereto was added dropwise 2 parts of 2,2′-azobis (2- (2-imidazolin-2-yl) propane)) 100% neutralized aqueous solution of acetic acid over 5 minutes. After aging for 5 minutes, 30 parts of methyl methacrylate was added dropwise over 5 minutes. After further aging for 5 minutes, 150 parts of methyl methacrylate, 35 parts of styrene, 25 parts of n-butyl methacrylate, γ-methacryloxy were added to a solution obtained by mixing 70 parts of acrylic resin having an ammonium group and 270 parts of deionized water. A pre-emulsion obtained by adding and stirring an α, β-ethylenically unsaturated monomer mixture having an alkoxysilyl group consisting of 60 parts of propyltriethoxysilane and 1 part of lauryl mercaptan was added dropwise over 40 minutes. After aging for 60 minutes, the mixture was cooled to obtain an aqueous resin particle dispersion. The obtained aqueous resin particle dispersion had a nonvolatile content of 37%, a pH of 4.7, and an average particle size measured by a laser light scattering method of 100 nm.

Example 3 Production of aqueous resin particles 3
In Example 1, the composition of the α, β-ethylenically unsaturated monomer mixture having an alkoxysilyl group was changed to 150 parts methyl methacrylate, 35 parts styrene, 55 parts n-butyl acrylate, 30 parts γ-methacryloxypropyltriethoxysilane. A water-based resin particle dispersion was obtained in the same manner except that it was changed to 1 part of lauryl mercaptan. The obtained aqueous resin particle dispersion had a non-volatile content of 38%, a pH of 5.0, and an average particle size measured by a laser light scattering method of 90 nm.

Example 4 Production of aqueous resin particles 4
In Example 1, the composition of the α, β-ethylenically unsaturated monomer mixture having an alkoxysilyl group was changed to 150 parts methyl methacrylate, 35 parts styrene, 55 parts n-butyl methacrylate, 30 parts γ-methacryloxypropyltriethoxysilane. An aqueous resin particle dispersion was obtained in the same manner except that the content was changed to 1 part of lauryl mercaptan and 40 parts of lauryl alcohol. The obtained aqueous resin particle dispersion had a non-volatile content of 38%, a pH of 5.0, and an average particle size measured by a laser light scattering method of 90 nm.

Comparative Example 1 Production of aqueous resin particles having no alkoxysilyl group In Example 1, the composition of the α, β-ethylenically unsaturated monomer mixture was not included in the α, β-ethylenically unsaturated monomer having an alkoxysilyl group. An aqueous resin particle dispersion was obtained in the same manner except that 160 parts of methyl methacrylate, 45 parts of styrene, 65 parts of n-butyl methacrylate, and 1 part of lauryl mercaptan were used. The obtained aqueous resin particle dispersion had a non-volatile content of 38%, a pH of 5.0, and an average particle size measured by a laser light scattering method of 90 nm.

Comparative Example 2 Production of Aqueous Crosslinked Resin Particles In Example 1, the composition of the α, β-ethylenically unsaturated monomer mixture having an alkoxysilyl group was changed to 165 parts methyl methacrylate, 30 parts styrene, 25 parts n-butyl methacrylate, γ -Aqueous crosslinked resin particle dispersion was obtained in the same manner except that 30 parts of methacryloxypropyltriethoxysilane and 25 parts of neopentyl glycol dimethacrylate were used. The obtained aqueous crosslinked resin particle dispersion had a nonvolatile content of 38%, a pH of 5.0, and an average particle size measured by a laser light scattering method of 90 nm.

Example 5 Production of Cationic Electrodeposition Coating Composition Containing Aqueous Resin Particles The base resin and the blocked isocyanate curing agent obtained in Production Examples 3 and 4, respectively, were uniformly mixed at a solid content blending ratio of 75:25, and then the solvent was added. An amount of 3% based on the solid content was added. Further, glacial acetic acid was added to neutralize to a neutralization rate of 43%, and then ion-exchanged water was added to slowly dilute. Subsequently, the main emulsion was obtained by removing MIBK under reduced pressure so that the solid content was 36%.
1500 parts of this main emulsion, 540 parts of pigment dispersion paste obtained in Production Example 2, 9.0 parts of dibutyltin oxide, and an aqueous resin obtained in Example 1 having a solid content equivalent to 10% of the resin solids in the paint The particles were mixed with 2000 parts of deionized water to prepare a cationic electrodeposition paint containing aqueous resin particles.

Examples 6 to 8 Production of a cationic electrodeposition coating composition containing aqueous resin particles In Example 5, aqueous resin particles were changed in the same manner except that the aqueous resin particles were changed to those obtained in Examples 2 to 4, respectively. A cationic electrodeposition coating composition containing was prepared.

Comparative Examples 3 and 4 Production of Comparative Cationic Electrodeposition Coating Composition In Example 5, the aqueous resin particles obtained in Comparative Example 1 were obtained without the alkoxysilyl group, and the aqueous crosslinking obtained in Comparative Example 2 A comparative cationic electrodeposition coating composition was prepared in the same manner except that each resin particle was changed.

Storage Stability Evaluation of Aqueous Resin Particles The aqueous resin particle dispersions obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were allowed to stand in a constant temperature room at 40 ° C. for 1 month. The solubility of each was visually evaluated. Further, for those in which no insoluble component was detected, the average particle size was measured by a laser light scattering method and compared with that immediately after production. The results are shown in Table 1.

○: Soluble in THF and average particle size unchanged Δ: Soluble in THF but increased average particle size ×: Insoluble component detected in THF

Evaluation of cationic electrodeposition paint <Coat smoothness>
The cationic electrodeposition coating compositions obtained in Examples 5 to 8 and Comparative Examples 3 and 4 were electrodeposited on a zinc phosphate-treated steel sheet at a voltage such that the film thickness after baking was 20 μm. Baked at 160 ° C. for 15 minutes to obtain a cured film. The smoothness of this coating film was measured for surface roughness (Ra) under the conditions of a cutoff of 0.8 mm and a scanning length of 4.0 mm using a surface roughness meter Surf Test-211 (manufactured by Mitutoyo Corporation). It was determined by evaluating with the criteria. Δ or more is acceptable.

○: Ra value less than 0.2 μm Δ: Ra value 0.2 μm or more and less than 0.3 μm ×: Ra value 0.3 μm or more

<Anti-repellency>
The cationic electrodeposition paints obtained in Examples 5 to 8 and Comparative Examples 3 and 4 were electrodeposited on a zinc phosphate-treated steel sheet at a voltage such that the film thickness after baking was 20 μm. After washing with water, it was allowed to stand at room temperature for 10 minutes. Then, place the painted plate horizontally and place it horizontally, fix the cup made of aluminum foil with a diameter of 14 mm and a height of 5 mm to the center of the painted plate with double-sided tape, and use a spoid to place water inside the aluminum foil cup. And a drop of rust preventive oil was added. The painted plate with the cup was kept horizontal and baked at 160 ° C. for 15 minutes. The repellency prevention property of the obtained cured coating film evaluated the state of the crater-shaped coating film which generate | occur | produced by oil scattering visually by the following evaluation criteria. Three or more points are acceptable.

5 points: No abnormalities such as craters on the coating film surface and smooth 4 points: Slight craters with a diameter of 2 mm or less are generated slightly on the coating film surface 3 points: Shallow craters with a diameter of 3 mm or less are generated on the coating film surface 2 points: Shallow craters larger than 3 mm in diameter are generated on the coating film surface 1 Point: Many craters larger than 3 mm in diameter are generated on the coating film surface Together with the evaluation results of coating film smoothness and repellency resistance Shown in Table 2

  In the examples of the present invention, both coating film smoothness and repellency prevention properties were excellent. In particular, the aqueous resin particles of Example 1 were excellent. In contrast, Comparative Example 1 containing aqueous resin particles having no alkoxyl group has poor repellency, and Comparative Example 2 containing crosslinked resin particles is inferior in coating film smoothness. Was confirmed to be excellent.

  Further, in Example 4, the storage stability of the resin particles is superior to others, and adding an alcohol to a monomer mixture containing an α, β-ethylenically unsaturated monomer having an alkoxysilyl group improves the storage stability. The improvement was confirmed.

  By adding the aqueous resin particles of the present invention, a cationic electrodeposition paint having both repellency prevention properties and smoothness of the coating film can be obtained.

Claims (8)

  Monomer mixture containing an α, β-ethylenically unsaturated monomer having an alkoxysilyl group, using a resin having an ammonium group, which is quaternized by adding a tertiary amine compound and an organic acid to a resin having an epoxy group, as a dispersant. Water-based resin particles obtained by emulsion polymerization.   2. The aqueous resin particle according to claim 1, wherein a solid content mass ratio between the resin having an ammonium group and the monomer mixture is 5/95 to 20/80.   3. The aqueous resin particle according to claim 1, wherein a proportion of the α, β-ethylenically unsaturated monomer having the alkoxysilyl group in the monomer mixture is 5 to 35 mass%.   The water-based resin particle according to any one of claims 1 to 3, which has a mass average molecular weight of 6000 to 12000.   The water-based resin particles according to any one of claims 1 to 4, wherein the monomer mixture has a glass transition temperature of 50 to 100C.   The water-based resin particle according to any one of claims 1 to 5, further comprising an alcohol having 1 to 18 carbon atoms.   Monomer mixture containing an α, β-ethylenically unsaturated monomer having an alkoxysilyl group, using a resin having an ammonium group, which is quaternized by adding a tertiary amine compound and an organic acid to a resin having an epoxy group, as a dispersant. A method for producing aqueous resin particles, characterized in that emulsion polymerization is carried out.   A cationic electrodeposition coating composition containing the aqueous resin particles according to any one of claims 1 to 6 in an amount of 3 to 20% by mass of the solid content of the coating resin.