JP2008111060A - Resin composition for water-based coating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition for a water-based coating having a long pot life and capable of forming a coating film excellent in initial hardness and appearance. <P>SOLUTION: The resin composition for the water-based coating contains a water-dispersive polyisocyanate composition (A) containing a hydrophobic polyisocyanate (a1), preferably a mixture of the hydrophobic polyisocyanate (a1) and a polyisocyanate (a2) having dispersibility to water; a resin (B) soluble or dispersive to water which has an active hydrogen-containing group that can react with an isocyanate group, preferably a vinyl polymer containing a hydroxyl group; a water-dispersive metallic catalyst (C), preferably one obtained by treating an organic metallic catalyst with an emulsifier to make it disperse in water; and water. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a resin composition for water-based paints which is excellent in workability and excellent in appearance, initial hardness, water resistance and the like of the cured product.

  In recent years, in various industrial fields, it has been strongly demanded from the viewpoint of workability and environmental problems to reduce the content of volatile organic solvents contained in applicable curable compositions. In order to meet this requirement, attempts have been made to make organic solvent-based curable compositions water-based, for example, by using water-based paints using an aqueous curable composition comprising a water-dispersible polyisocyanate and a hydroxyl group-containing aqueous resin. It has been reported that a coating film excellent in hardness, appearance, water resistance and adhesion can be provided (see, for example, Patent Document 1).

  On the other hand, there is a demand from the market for the development of a resin composition for water-based paints that can exhibit higher performance in various applications. For example, it is a resin composition for water-based paints excellent in so-called initial hardness in which the curing reaction proceeds not only in hardness after about one week after coating but also in a relatively short time such as several hours after coating or the next day. However, the coating film obtained from the water-based paint using the resin composition for water-based paint described in Patent Document 1 does not have sufficient initial hardness under curing conditions at room temperature or lower.

  In order to solve this problem, when a metal catalyst used in a solvent-type urethane paint or the like is used, the appearance and hardness of the resulting coating film are poor because of poor mixing with the resin composition for aqueous paint. It is enough. Furthermore, when the amount of the catalyst is increased to improve the initial hardness, there is a problem that the pot life is shortened and workability is deteriorated.

Japanese Patent Laying-Open No. 2005-200197

  The subject of this invention is providing the resin composition for water-based paints which can form the coating film which is long in pot life and is excellent in initial hardness and external appearance.

  As a result of diligent research to solve the above problems, the present inventors have found that the water-dispersible polyisocyanate composition (A) containing the hydrophobic polyisocyanate (a1), containing active hydrogen capable of reacting with isocyanate groups When the resin (B) having a group and soluble or dispersible in water, the water-dispersed metal catalyst (C) and the resin composition for water-based paints containing water are used, the pot life is long and the initial hardness and appearance are improved. The inventors have found that a water-based paint capable of forming an excellent coating film can be easily obtained, and have completed the present invention.

  That is, the present invention relates to a water-dispersible polyisocyanate composition (A) containing a hydrophobic polyisocyanate (a1), a resin having an active hydrogen-containing group capable of reacting with an isocyanate group and soluble or dispersible in water (B ), A water-dispersed metal catalyst (C) and water, and a resin composition for water-based paints.

  By using the resin composition for water-based paints of the present invention, even when the organic solvent is not contained or the content thereof is extremely small, a usable life is long, and a coating film excellent in initial hardness, appearance, etc. A water-based paint that can be formed can be easily obtained.

Hereinafter, the present invention will be described in more detail.
First, the water dispersible polyisocyanate composition (A) used in the present invention will be described.

  The water-dispersible polyisocyanate composition (A) used in the present invention may be any polyisocyanate composition containing a hydrophobic polyisocyanate (a1) and has water-dispersibility. And a mixture of a water-dispersible compound capable of water-dispersing the water-soluble polyisocyanate (a1). Specific examples include (1) a mixture of a hydrophobic polyisocyanate (a1) and a water-dispersible polyisocyanate (a2), and (2) a hydrophobic polyisocyanate (a1) and a hydrophilic group that does not have an isocyanate group. And a mixture of the dispersant (a3) having In particular, a mixture of the hydrophobic polyisocyanate (a1) of (1) and the polyisocyanate (a2) having water dispersibility can be obtained because a water-based paint capable of forming a coating film having excellent hardness, water resistance and solvent resistance is obtained. Is preferred. The polyisocyanate (a2) having water dispersibility and the dispersant (a3) having no isocyanate group but having a hydrophilic group can be used in combination.

  Examples of the hydrophobic polyisocyanate (a1) include those having no hydrophilic group such as an anionic group, a cationic group, and a nonionic group in the molecule. For example, 1,4-tetramethylene diisocyanate, ethyl Aliphatic diisocyanates such as (2,6-diisocyanato) hexanoate, 1,6-hexamethylene diisocyanate, 1,12-dodecamethylene diisocyanate, 2,2,4- or 2,4,4-trimethylhexamethylene diisocyanate; Aliphatic triisocyanates such as 1,3,6-hexamethylene triisocyanate, 1,8-diisocyanate-4-isocyanate methyloctane, 2-isocyanatoethyl (2,6-diisocyanate) hexanoate;

1,3- or 1,4-bis (isocyanatomethylcyclohexane), 1,3- or 1,4-diisocyanatocyclohexane, 3,5,5-trimethyl (3-isocyanatomethyl) cyclohexyl isocyanate, dicyclohexylmethane Cycloaliphatic diisocyanates such as -4,4'-diisocyanate, 2,5- or 2,6-diisocyanatomethylnorbornane; 2,5- or 2,6-diisocyanatomethyl-2-isocyanate propylnorbornane Alicyclic diisocyanates such as m-xylylene diisocyanate, aralkylene diisocyanates such as α, α, α ′, α′-tetramethyl-m-xylylene diisocyanate;

m- or p-phenylene diisocyanate, tolylene-2,4- or 2,6-diisocyanate, diphenylmethane-4,4'-diisocyanate, naphthalene-1,5-diisocyanate, diphenyl-4,4'-diisocyanate, 4,4 Aromatic diisocyanates such as' -diisocyanate-3,3'-dimethyldiphenyl, 3-methyl-diphenylmethane-4,4'-diisocyanate, diphenyl ether-4,4'-diisocyanate; triphenylmethane triisocyanate, tris (isocyanate) Aromatic triisocyanates such as natephenyl) thiophosphate;

Polyisocyanates having a uretdione structure obtained by cyclizing and dimerizing the isocyanate groups of the various diisocyanates or triisocyanates described above; Isocyanates obtained by cyclizing and trimerizing the isocyanate groups of the various diisocyanates or triisocyanates described above Polyisocyanate having a nurate structure; polyisocyanate having a burette structure obtained by reacting the above-mentioned various diisocyanates or triisocyanates with water; oxadiater obtained by reacting the various diisocyanates or triisocyanates with carbon dioxide Examples include polyisocyanates having a gintrione structure; polyisocyanates having an allophanate structure.

  Among the hydrophobic polyisocyanates (a1), a resin composition for water-based paints capable of forming a coating film having excellent weather resistance can be obtained. Therefore, aliphatic or alicyclic diisocyanates or triisocyanates, aralkylene diisocyanates Or derivatives thereof are preferred.

  Examples of the hydrophobic polyisocyanate (a1) include isocyanurate type polyisocyanates, polyisocyanates having a burette structure, polyisocyanates having a uretdione structure, polyisocyanates having an allophanate structure, diisocyanates and trihydric or higher polyhydric alcohols. A tri- or higher functional polyisocyanate such as polyisocyanate obtained by the reaction is preferable because a resin composition for water-based paints capable of forming a coating film having excellent weather resistance and durability can be obtained.

  Examples of the water-dispersible polyisocyanate (a2) include polyisocyanates having hydrophilic groups, and examples of such hydrophilic groups include anionic groups, cationic groups, and nonionic groups. Among them, a polyisocyanate having a nonionic group as a hydrophilic group is preferable since a resin composition for water-based paints capable of forming a coating film having excellent water resistance is obtained. Specifically, a polyoxyethylene group is preferable. More preferred is a polyisocyanate having

  Examples of the water-dispersible polyisocyanate (a2) include polyethers, polyesters, polyurethanes, vinyl polymers, alkyd resins, fluororesins, and silicone resins having an isocyanate group and a hydrophilic group. These can be used singly or in combination of two or more. However, since the polyisocyanate composition having excellent water dispersibility and water dispersibility can be easily obtained by mixing with the hydrophobic polyisocyanate (a1), the isocyanate group and the hydrophilic property can be obtained. A vinyl polymer (a21) having a group is preferred.

  Examples of the vinyl polymer (a21) having an isocyanate group and a hydrophilic group include an acrylic polymer, a fluoroolefin polymer, a vinyl ester polymer, and an aromatic vinyl having an isocyanate group and a hydrophilic group. In the case where the resin (B) having an active hydrogen-containing group capable of reacting with an isocyanate group described later and soluble or dispersible in water is an acrylic polymer, these may be mentioned. Therefore, it is preferable to use an acrylic polymer or a fluoroolefin polymer having an isocyanate group and a hydrophilic group.

  The vinyl polymer (a21) having an isocyanate group and a hydrophilic group is, for example, a) a vinyl polymer containing a vinyl monomer having an isocyanate group and a vinyl monomer having a hydrophilic group. A method of polymerizing a monomer mixture; b) obtained by polymerizing a vinyl monomer mixture containing a vinyl monomer having an active hydrogen-containing group and a vinyl monomer having a hydrophilic group. It can be produced by a production method such as a method of reacting an active hydrogen-containing group of a vinyl polymer with a polyisocyanate.

  Examples of the vinyl monomer having an isocyanate group used in the production method a) include 2-isocyanatopropene, 2-isocyanatoethyl vinyl ether, 2-isocyanatoethyl methacrylate, m-isopropenyl-α, Examples include α-dimethylbenzyl isocyanate, reaction products of polyisocyanate and a vinyl monomer having a hydroxyl group.

  Examples of the vinyl monomer having a hydrophilic group used in the production method a) include alkoxypolyoxyethylene such as methoxypolyethylene glycol (meth) acrylate, butoxypolyethylene glycol (meth) acrylate, and methoxypolyoxyethylene vinyl. Examples thereof include vinyl monomers having a group, anionic group-containing vinyl monomers such as sodium alkylallylsulfonate and sodium alkylallylphosphate.

  Examples of the active hydrogen-containing group in the vinyl monomer having an active hydrogen-containing group used in the production method (b) include, for example, a hydroxyl group, a carboxyl group, a phosphoric acid group, a phosphorous acid group, a sulfonic acid group, a sulfinic acid group, Mercapto group, silanol group, active methylene group, carbamate group, ureido group, carboxylic acid amide group, sulfonic acid amide group and the like can be mentioned. Among them, the introduction of the active hydrogen-containing group into a vinyl polymer is easy. Therefore, a hydroxyl group, an amino group, a carboxyl group, and an active methylene group are preferable, and a hydroxyl group and a carboxyl group are more preferable. One kind of the active hydrogen-containing group may be introduced alone or two or more kinds may be introduced into the vinyl polymer.

  Examples of the vinyl monomer having an active hydrogen-containing group used in the production method (b) include acrylate monomers such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate. Moreover, as a vinyl-type monomer which has a hydrophilic group, the thing similar to what is used by the said manufacturing method a) can be used.

  In the production methods a) and b), it is preferable to use a vinyl monomer having a hydrophobic group having 4 or more total carbon atoms in combination. By using such a vinyl monomer, the reaction between the water-dispersible polyisocyanate composition (A) and water can be prevented, and the resin composition for water-based paints of the present invention has a sufficient pot life. It becomes possible to make it.

  As a method for introducing a hydrophobic group having 4 or more total carbon atoms into the vinyl polymer (a21) having an isocyanate group and an aqueous group, for example, in the above-described production method a) or b), Examples thereof include a method in which a vinyl monomer having a hydrophobic group having 4 or more carbon atoms is used as a part of the vinyl monomer mixture for copolymerization.

  Examples of the vinyl monomer having a hydrophobic group having 4 or more total carbon atoms include n-butyl group, iso-butyl group, tert-butyl group, n-pentyl group, n-hexyl group, Vinyl monomers having an alkyl group having 4 or more carbon atoms such as 2-ethylhexyl group, n-octyl group, n-dodecyl group, n-octadecyl group; cyclopentyl group, cyclohexyl group, cyclooctyl group, dicyclo Examples thereof include vinyl monomers having a cycloalkyl group having 4 or more carbon atoms such as a pentanyl group, a bornyl group, and an isobornyl group, and specifically, acrylates such as n-butyl acrylate and n-butyl methacrylate. Monomer.

  In the vinyl polymer (a21) having an isocyanate group and a hydrophilic group, in addition to the various vinyl monomers described above, other vinyl monomers can be used within the scope of achieving the object of the present invention. Can be used together.

  Examples of the other vinyl monomers include acrylic monomers such as methyl acrylate and methyl methacrylate.

  The weight-average molecular weight of the vinyl polymer (a21) having an isocyanate group and a hydrophilic group thus obtained is determined by using the vinyl polymer (a21) as a water-dispersible polyisocyanate (a2) and a hydrophobic polyisocyanate (a1). 2), a water-dispersible polyisocyanate composition obtained by mixing with water) has a good dispersibility in water and stability of the isocyanate group in water, and a resin composition for water-based paints having excellent curability is obtained. The range of 000 to 100,000 is preferable, and the range of 3,000 to 50,000 is more preferable.

  The vinyl polymer (a21) having an isocyanate group and a hydrophilic group is preferably mixed with the hydrophobic polyisocyanate (a1) and used as a water-dispersible polyisocyanate composition. The weight ratio (a1 / a21) of the polyisocyanate (a1) and the vinyl polymer (a21) having an isocyanate group and a hydrophilic group is preferably in the range of 3/7 to 9.5 / 0.5. The range of 5-9 / 1 is more preferable, and the range of 6 / 4-8 / 2 is still more preferable.

  A water-dispersible polyisocyanate composition comprising a mixture of the vinyl polymer (a21) having an isocyanate group and a hydrophilic group and the hydrophobic polyisocyanate (a1) is, for example, hydrophobic in the production method (a) or (b). Can be easily produced by a one-step reaction using an excess amount of the functional polyisocyanate (a1).

  Examples of the dispersant (a3) that does not have an isocyanate group but has a hydrophilic group include, for example, an acrylic polymer, a fluoroolefin polymer, and a vinyl ester type that do not have an isocyanate group but have a hydrophilic group. Examples thereof include a polymer, an aromatic vinyl polymer, and a polyolefin polymer. Among the dispersants (a3) having no isocyanate group but having a hydrophilic group, a resin (B) which has an active hydrogen-containing group capable of reacting with an isocyanate group described later and which can be dissolved or dispersed in water is acrylic. In the case of a polymer, it is preferable to use an acrylic polymer or a fluoroolefin polymer that does not have an isocyanate group but has a hydrophilic group because of their good compatibility.

  When the dispersant (a3) having no isocyanate group but having a hydrophilic group is mixed with the hydrophobic polyisocyanate (a1) and used as a water-dispersible polyisocyanate composition, these weight ratios (a1) / A3) is preferably within the range of 3/7 to 9.5 · 0.5, more preferably within the range of 5/5 to 9/1, and even more preferably within the range of 6/4 to 8/2.

  The hydrophobic polyisocyanate (a1), the water-dispersible polyisocyanate (a2), and the dispersant (a3) having no isocyanate group but having a hydrophilic group all achieve the object of the present invention. In such a range, it can be used after diluted with an organic solvent inert to the isocyanate group.

  Examples of the organic solvent inert to the isocyanate group include aliphatic or alicyclic hydrocarbons such as n-hexane, n-heptane, n-octane, cyclohexane, cyclopentane, and mineral spirits; Aromatic hydrocarbons such as toluene, xylene, ethylbenzene; esters such as ethyl acetate, n-butyl acetate, n-amyl acetate, ethylene glycol monomethyl ether acetate; acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl n-amyl ketone, cyclohexanone Ketones such as;

Polyalkylene glycol dialkyl ethers such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether and dipropylene glycol dimethyl ether; polyalkylene glycol monoalkyl ether acetates such as ethylene glycol methyl ether acetate, propylene glycol methyl ether acetate and diethylene glycol methyl ether acetate Ethers such as 1,2-dimethoxyethane, tetrahydrofuran and dioxane; N-methylpyrrolidone, dimethylformamide, dimethylacetamide, ethylene carbonate and the like can be mentioned, and these can be used alone or in combination of two or more.

  Next, the resin (B) which has an active hydrogen-containing group capable of reacting with the isocyanate group used in the present invention and can be dissolved or dispersed in water will be described.

  The resin (B) used in the present invention is soluble or dispersible in water and has an active hydrogen-containing group capable of reacting with an isocyanate group in the water-dispersible polyisocyanate composition (A). The form, type, and the like are not limited, and may be any of water-soluble resins, self-water dispersible resins, resins that are water-dispersible by using a dispersant, and the like. Examples of the active hydrogen-containing group possessed by the resin (B) include a functional group having an active methylene group such as a hydroxyl group, a carboxyl group, an amino group, an amide group, and an acetoacetyl group. Among these, a hydroxyl group is preferable.

  The resin (B) can be easily mixed with water and used as an aqueous solution or an aqueous dispersion such as a colloidal dispersion or an emulsion.

  Examples of the resin (B) include a vinyl acetate resin, a styrene-butadiene resin, a styrene-acrylonitrile resin, an acrylic resin, a fluoroolefin resin that can be dissolved or dispersed in water and has the active hydrogen-containing group. Resins, silicon-modified vinyl polymers, vinyl polymers such as polyvinyl alcohol; polyester resins, polyurethane resins, phenol resins, melamine resins, epoxy resins, alkyd resins, polyamide resins, polyether resins, Synthetic resins other than vinyl polymers such as silicone resins; natural polymers such as animal proteins, starches, cellulose derivatives, dextrin, gum arabic, etc., preferably vinyl polymers, more preferably hydroxyl group-containing vinyls Based polymer. These can be used alone or in combination of two or more.

  The amount of the active hydrogen-containing group contained in the resin (B) is 0.1 to 6 per 1000 g of the resin (B) because a resin composition for water-based paints excellent in curability and water resistance of the coating film is obtained. Moles are preferred, 0.2-4 moles are more preferred, and 0.4-3 moles are most preferred.

  Among the resins (B), the hydroxyl group-containing vinyl polymer can be produced, for example, by subjecting a vinyl monomer having a hydroxyl group or other vinyl monomers to radical polymerization or redox polymerization.

  Examples of the vinyl monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl acrylate, 2-hydroxypropyl (meth) acrylate, and the like.

  Examples of the other vinyl monomers include styrene, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate, acrylamide, and the like.

  The radical polymerization described above is roughly classified into an emulsion polymerization method using water as a solvent and a solution polymerization method using an organic solvent as a solvent, and both methods can be applied.

  The solution polymerization method is a method in which the above-described vinyl monomer having a hydroxyl group, other vinyl monomers and an initiator are added to an organic solvent for copolymerization. The resin (B) can be produced by removing the solvent.

  Examples of the organic solvent include diluting the hydrophobic polyisocyanate (a1), the polyisocyanate (a2) having water dispersibility, and the dispersant (a3) having no isocyanate group but having a hydrophilic group. The thing similar to the organic solvent inactive with respect to the isocyanate group which can be used can be used.

  Examples of the initiator include 2,2′-azobis (isobutyronitrile), 2,2′-azobis (2,4-dimethylbutyronitrile), and 2,2′-azobis (2-methylbutyronitrile). Various azo compounds such as nitrile); tert-butyl peroxypivalate, tert-butyl peroxybenzoate, tert-butyl peroxy-2-ethylhexanoate, di-tert-butyl peroxide, cumene hydroperoxide And peroxides such as diisopropyl peroxycarbonate.

  Further, as the hydroxyl group-containing vinyl polymer obtained by the solution polymerization method, a hydroxyl group-containing vinyl polymer having a neutralized carboxyl group, such as acrylic acid, can be easily dissolved or dispersed in water. Then, after copolymerizing a vinyl monomer having a carboxyl group such as methacrylic acid and maleic acid with a vinyl monomer having a hydroxyl group as described above to obtain a hydroxyl group-containing vinyl polymer having a carboxyl group, A hydroxyl group-containing vinyl polymer that is neutralized with a basic compound and is soluble or dispersible in water is preferred.

  Examples of the basic compound include amines such as triethylamine, dimethylethanolamine, and ammonia (ammonia water); alkali metals such as sodium hydroxide and potassium hydroxide.

  In addition, the emulsion polymerization method using water as a solvent is a method in which a vinyl monomer having a hydroxyl group described above, other vinyl monomers and an emulsifier are added to water for copolymerization. Examples of emulsifiers that can be used at this time include nonionic properties such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene polycyclic phenyl ether, polyoxyethylene-polyoxypropylene block copolymer, and sorbitan fatty acid ester. Emulsifier: Higher alcohol sulfate ester, alkylbenzene sulfonate, alkyl diphenyl ether disulfonate, polyoxyethylene alkylphenyl ether sulfate, polyoxyethylene alkyl ether sulfate, polyoxyethylene polycyclic phenyl ether sulfate, polyoxyethylene Alkyl sulfonate, alkyl ether phosphate, alkenyl succinate, dialkyl sulfosuccinate, monoalkyl sulfosuccinic acid Anionic emulsifiers such as N; N-dimethyllaurylamine, cationic emulsifiers such as tertiary amine carboxylates and quaternary ammonium salts having a long-chain alkyl group such as N, N-dimethyloctadecylamine; carboxylate bases A compound having both an anionic group and a double bond such as a sulfate group and a phosphate group, a compound having both a nonionic group and a polymerizable double bond, and a cationic group such as a quaternary ammonium base and a polymerizable double bond Examples include reactive emulsifiers such as compounds that are also present. Two or more of these emulsifiers can be used in combination.

  Since the above-mentioned emulsifier does not reduce the water resistance of the coating film obtained using the resin composition for water-based paints of the present invention, 0.1 to 10 parts per 100 parts by weight of the total vinyl monomer used. It is preferable to use in the range of parts by weight, and more preferable to use in the range of 0.5 to 5 parts by weight.

  In the emulsion polymerization method, the resin (B) can be obtained by redox polymerization of the above-described vinyl monomer having a hydroxyl group and other vinyl monomers by using a reducing agent.

  As the hydroxyl group-containing vinyl polymer obtained by the emulsion polymerization method, those having a carboxyl group are preferable. For example, a vinyl monomer having a carboxyl group such as acrylic acid, methacrylic acid, maleic acid, etc. By being copolymerized with a vinyl monomer having a hydroxyl group, a carboxyl group can be introduced into the vinyl polymer. In addition, the carboxyl group at this time may be neutralized by the above-described basic compound to form a carboxylate.

  Among such hydroxyl group-containing vinyl polymers, a vinyl monomer having a hydroxyl group, a vinyl monomer having a carboxyl group, and other vinyl monomers are solution-polymerized and then neutralized with a basic compound. Preferred is a vinyl polymer obtained by emulsion polymerization of a vinyl monomer having a hydroxyl group and another vinyl monomer.

  In addition, since the vinyl polymer obtained by the emulsion polymerization is obtained as an aqueous dispersion, it can be used as it is in the resin composition for water-based paints of the present invention without being separated. Since the vinyl polymer obtained by neutralization with a basic compound is obtained as an organic solvent solution, this solution and water are mixed and phase-inverted and emulsified, and the organic solvent is removed if necessary. It is preferable to use it after performing the conversion treatment.

Next, the water-dispersed metal catalyst (C) used in the present invention will be described.
The water-dispersed metal catalyst (C) used in the present invention may be any metal catalyst that can be dispersed in water, and examples thereof include those obtained by subjecting a metal catalyst to water dispersion treatment with a dispersant or the like. Especially, since the resin composition for water-based paints which forms the coating film which is excellent in initial stage hardness is obtained, what processed the organometallic catalyst with the emulsifier and was water-dispersed is preferable.

  Examples of the metal contained in the organometallic catalyst include cobalt, zinc, manganese, zirconium, bismuth, lithium, potassium, calcium, magnesium, iron, copper, nickel, aluminum, and barium. Cobalt, zinc, and zirconium are preferred because a coating film excellent in the initial hardness of a cured product obtained using the aqueous curable composition can be formed, and a resin composition for an aqueous coating with a low environmental load can be obtained.

  Further, the organometallic catalyst is selected from the group consisting of cobalt, zinc and zirconium because a coating composition having excellent initial hardness and appearance can be formed, and a resin composition for water-based paints having a low environmental load can be obtained. A salt composed of at least one kind of metal and an organic acid is preferable, and a salt composed of a fatty acid is particularly preferable.

  Examples of such fatty acids include naphthenic acid, octylic acid, neodecanoic acid, stearic acid, oleic acid and the like.

  Specific examples of the organometallic catalyst include cobalt compounds such as cobalt naphthenate, cobalt octylate, and acetylacetone cobalt; zinc compounds such as zinc naphthenate, zinc octylate, and zinc acetylacetone; manganese naphthenate, manganese octylate, and acetylacetone Manganese compounds such as manganese; zirconium compounds such as zirconium naphthenate, zirconium octylate and zirconium acetylacetone; bismuth compounds such as bismuth naphthenate, bismuth octylate and bismuth neodecanoate; lithium compounds such as lithium naphthenate and lithium octylate; Potassium compounds such as potassium acid and potassium octylate; calcium compounds such as calcium naphthenate, calcium octylate and calcium acetylacetone; naphthe Magnesium compounds such as magnesium acid and magnesium acetylacetone; Iron compounds such as iron naphthenate, iron octylate and iron acetylacetone; Copper compounds such as copper naphthenate and copper acetylacetone; Nickel compounds such as nickel octylate and nickel acetylacetone; Aluminum octylate And aluminium compounds such as acetylacetone aluminum; and barium compounds such as acetylacetone barium.

  As the emulsifier, any of the above-described nonionic emulsifiers, anionic emulsifiers, and cationic emulsifiers can be used as an emulsifier used in the emulsion polymerization method for obtaining the resin (B), and two or more kinds can be used in combination. .

  The emulsifier is preferably used in an amount of 2 to 30 parts by weight with respect to 100 parts by weight of the solid content of the metal catalyst because a resin composition for water-based paints capable of forming a coating film having excellent water resistance is obtained. It is more preferable to use 20 parts by weight.

  Examples of the method of treating the metal catalyst with the emulsifier to form a water-dispersed metal catalyst include a method of mixing the emulsifier aqueous solution and the metal catalyst after dissolving the emulsifier in water to obtain an aqueous emulsifier solution. It is done. The temperature which melt | dissolves an emulsifier in water is 20-90 degreeC normally, Preferably it is 50-85 degreeC. Moreover, the mixing temperature of the emulsifier aqueous solution and the metal catalyst is usually 20 to 80 ° C., preferably 40 to 70 ° C., and the mixing time is usually 3 to 20 hours, preferably 5 to 15 hours.

  In addition, the said water dispersion type metal catalyst (C) can also contain an organic solvent in the range which achieves the objective of this invention.

  As the organic solvent, various organic solvents can be used. For example, the hydrophobic polyisocyanate (a1), the water-dispersible polyisocyanate (a2), and a dispersion having no isocyanate group but having a hydrophilic group. An organic solvent inert to the isocyanate group that can be used when diluting the agent (a3) is preferred.

  Among these organic solvents, a water-borne resin composition having excellent water dispersibility of the water-dispersible metal catalyst (C) is obtained, so that n-hexane, n-heptane, n-octane, cyclohexane, cyclopentane, mineral Aliphatic or alicyclic hydrocarbons such as spirit are preferred.

  The resin composition for water-based paints of the present invention comprises the water-dispersible polyisocyanate composition (A), the resin (B), the water-dispersible metal catalyst (C), and water. The thing melt | dissolved or disperse | distributed to water is mentioned. As a method of mixing these, for example, the water-dispersed metal catalyst (C) is added to the aqueous solution or dispersion of the resin (B) and stirred, and further the water-dispersed polyisocyanate composition (A) is dispersed in water. The method etc. which add a body etc. and stir are mentioned. As a stirring method, for example, there are methods using various stirrers, and if it is a small amount, it can be easily and uniformly mixed by simple stirring using a stirring rod or the like. The use of a stirrer is preferable because a large amount of the resin composition for water-based paint can be prepared in a short time.

  Since the mixing ratio of the resin (B) and the water-dispersed metal catalyst (C) at this time is long, the resin composition for water-based paints having excellent initial hardness and appearance can be obtained. It is preferable that the metal content in the water-dispersed metal catalyst (C) is 0.005 to 5.0 parts by weight with respect to 100 parts by weight of the solid content of (B), and 0.02 to 2.0 More preferred are parts by weight.

  Further, the mixing ratio of the water-dispersible polyisocyanate composition (A) and the resin (B) is such that the pot life is long and the resin composition for water-based paints having excellent initial hardness, appearance, etc. is obtained. The molar ratio (NCO / OH) of the isocyanate group (NCO) in the water-dispersible polyisocyanate composition (A) and the hydroxyl group (OH) in the resin (B) that can be dissolved or dispersed in water is 0.1 to 0.1. 5 is preferable, 0.3 to 3 is more preferable, and 0.5 to 2 is still more preferable.

  The resin composition for water-based paints of the present invention can be used as it is as a clear composition containing no pigment as it is, or it can also be used as a colored paint by blending various organic or inorganic pigments. . In addition, for such paints, additives suitable for various applications, for example, fillers, leveling agents, thickeners, antifoaming agents, organic solvents, ultraviolet absorbers, antioxidants, pigment dispersants as necessary. It can be used by blending various additives.

  And the water-based paint obtained using the resin composition for water-based paints of this invention has a long pot life, and can obtain the cured coating film which is excellent in initial hardness and external appearance.

  Next, although a reference example, an example, and a comparative example explain the present invention in detail, the present invention is not limited to this. All parts and% in the text are based on weight unless otherwise specified.

First, the polyisocyanate used in Examples and Comparative Examples will be described.
Hydrophobic polyisocyanate (XA-1): Hexamethylene diisocyanate-based isocyanurate type polyisocyanate “Bernock DN-980S” [manufactured by Dainippon Ink & Chemicals, Inc., isocyanate group content (hereinafter abbreviated as NCO group content) 21), average NCO functional group number 3.6, nonvolatile content 100%]

Reference Example 1 [Preparation Example of Water Dispersible Polyisocyanate Composition (A-1)]
After charging 200 parts of diethylene glycol diethyl ether (hereinafter abbreviated as DEDG) into a four-necked flask equipped with a stirrer, a thermometer, a cooling pipe and a nitrogen introduction pipe, the temperature was raised to 110 ° C. under a nitrogen stream, Methoxy polyethylene glycol methacrylate (containing 9 average oxyethylene units per molecule) 100 parts, methyl methacrylate (hereinafter abbreviated as MMA) 60 parts, 2-hydroxyethyl methacrylate (hereinafter abbreviated as 2-HEMA) A mixed solution consisting of 10 parts, 30 parts of cyclohexyl methacrylate, 5 parts of t-butylperoxy-2-ethylhexanoate and 1 part of t-butylperoxybenzoate was added dropwise over 5 hours. After the dropping, the mixture was reacted at 110 ° C. for 9 hours to obtain an acrylic polymer solution having a nonvolatile content of 50%. Next, 600 parts of hydrophobic polyisocyanate (XA-1) was added, the temperature was raised to 95 ° C., and the mixture was reacted at the same temperature for 6 hours to obtain a water-dispersible polyisocyanate composition having a non-volatile content of 80% and an NCO group content of 12%. (A-1) was obtained.

Reference Example 2 [Preparation Example of Water Dispersible Polyisocyanate Composition (A-2)]
In a four-necked flask similar to Reference Example 1, 200 parts of DEDG, 143 parts of methoxypolyethylene glycol (molecular weight: 400) and 657 parts of hydrophobic polyisocyanate (XA-1) were charged, and the temperature was raised to 95 ° C. over 30 minutes. Then, the mixture was reacted at 95 ° C. for 6 hours to obtain a water-dispersible polyisocyanate composition (A-2) modified with methoxypolyethylene glycol having a nonvolatile content of 80% and an NCO group content of 12%.

Reference Example 3 [Preparation example of hydroxyl group-containing acrylic resin emulsion (B-1)]
In a four-necked flask similar to Reference Example 1, 5 parts of “Hytenol N-08” (anionic emulsifier manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), “Emulgen 931” [nonionic emulsifier manufactured by Kao Corporation] 5 parts and 270 parts of deionized water were charged and heated to 80 ° C. under a nitrogen stream, and then an aqueous solution in which 0.8 part of ammonium persulfate was dissolved in 16 parts of deionized water was added. Further, 80 parts of butyl acrylate (hereinafter abbreviated as BA), 87 parts of MMA, 4 parts of acrylic acid (hereinafter abbreviated as AA), 14 parts of 2-HEMA and 2-hydroxypropyl methacrylate (hereinafter referred to as 2-HPMA) (Abbreviated.) A mixture of 15 parts was added dropwise over 3 hours. After dropping, the mixture was reacted for 2 hours, cooled to 25 ° C., neutralized with 1.5 parts of 28% aqueous ammonia, and a hydroxyl group-containing acrylic resin emulsion (B) having a nonvolatile content of 43% and a solid content hydroxyl value of 60 mgKOH / g. -1) was obtained.

Reference Example 4 [Preparation example of hydroxyl group-containing acrylic resin dispersion (B-2)]
In a four-necked flask similar to Reference Example 1, 60 parts of DEDG was charged and heated to 125 ° C. under a nitrogen stream, and then a mixed solution consisting of 80 parts of BA, 87 parts of MMA, 4 parts of AA and 14 parts of 2-HEMA, and t A mixed solution consisting of 20 parts of butyl peroxy-2-ethylhexanoate and 1 part of t-butyl peroxybenzoate was added dropwise over 5 hours. After the dropwise addition, the mixture was reacted at 125 ° C. for 5 hours, then cooled to 60 ° C., 5.6 parts of triethylamine was added, and the mixture was mixed at 60 ° C. for 30 minutes. Then, 461 parts of ion exchange water was added dropwise over 2 hours, and then cooled to 25 ° C. to obtain a hydroxyl group-containing acrylic resin dispersion (B-2) having a nonvolatile content of 30% and a solid content hydroxyl value of 60 mgKOH / g.

Reference Example 5 [Preparation example of water-dispersed metal catalyst (C-1)]
The same four-necked flask as in Reference Example 1 was charged with 10 parts of “New Coal 707SF” (anionic emulsifier manufactured by Nippon Emulsifier Co., Ltd.) and 150 parts of deionized water, and the mixture was heated to 80 ° C. and mixed. Then, the temperature was lowered to 60 ° C., and 150 parts of “Co-NAPHTHENATE 6%” (cobalt naphthenate manufactured by Dainippon Ink & Chemicals, Inc.) was charged over 3 hours. The mixture was stirred at the same temperature for 10 hours to obtain a water-dispersed metal catalyst (C-1) having a metal content of 3.0%.

Reference Example 6 [Preparation example of water-dispersed metal catalyst (C-2)]
In a four-necked flask similar to that in Reference Example 1, 10 parts of “New Coal 707SF” and 150 parts of deionized water were charged and heated to 80 ° C. and mixed. Thereafter, the temperature was lowered to 60 ° C., and 150 parts of “Zn-NAPHTHENATE 5%” [Zinc naphthenate manufactured by Dainippon Ink & Chemicals, Inc.] were charged over 3 hours. The mixture was stirred at the same temperature for 10 hours to obtain a water-dispersed metal catalyst (C-2) having a metal content of 2.5%.

Reference Example 7 [Preparation Example of Water Dispersible Metal Catalyst (C-3)]
In a four-necked flask similar to that in Reference Example 1, 10 parts of “New Coal 707SF” and 150 parts of deionized water were charged and heated to 80 ° C. and mixed. Thereafter, the temperature was decreased to 60 ° C., and 150 parts of “Zn-OCTOATE 8%” [Dainippon Ink & Chemicals, Inc., zinc octylate] was charged over 3 hours. The mixture was stirred at the same temperature for 10 hours to obtain a water-dispersed metal catalyst (C-3) having a metal content of 3.9%.

Reference Example 8 [Preparation Example of Water Dispersible Metal Catalyst (C-4)]
In a four-necked flask similar to that in Reference Example 1, 10 parts of “New Coal 707SF” and 150 parts of deionized water were charged and heated to 80 ° C. and mixed. Thereafter, the temperature was decreased to 60 ° C., and 150 parts of “Zr-OCTOATE 8%” (Dainippon Ink & Chemicals, Inc., zirconium octylate) was charged over 3 hours. The mixture was stirred at the same temperature for 10 hours to obtain a water-dispersed metal catalyst (C-4) having a metal content of 5.8%.

Example 1
After adding 10 parts of the water-dispersible metal catalyst (C-1) to 500 parts of the hydroxyl group-containing acrylic resin emulsion (B-1), 80 parts of the water-dispersible polyisocyanate composition (A-1) and deionized water are further added. 100 parts was mixed to prepare a resin composition for water-based paint (D-1). The pot life of the obtained water-borne resin composition (D-1), the appearance of the cured coating film, and the initial hardness were evaluated as follows, and the results are shown in Table 1 (1).

“Usable time”: The change in viscosity when the resin composition for water-based paints was stored at 20 ° C. for 3 hours was evaluated. The evaluation criteria at that time are as follows.
○: Almost no change.
X: Significant thickening or gelation.

“Appearance”: The resin composition for water-based paints just prepared was applied on a glass plate using an applicator so that the film thickness of the cured coating film was 40 μm, and the temperature was 20 ° C. and the humidity was 60% RH for one week. The surface state of the cured coating film after drying and curing was visually evaluated. The evaluation criteria at that time are as follows.
○: No stuff.
Δ: A small amount of irregularities.
X: There is a large amount of irregularities.

“Initial hardness”: The resin composition for water-based paints immediately after preparation was applied on a glass plate using an applicator so that the film thickness of the cured coating film was 40 μm, and the temperature was 20 ° C. and the humidity was 60% RH. After drying and curing for a period of time, the hardness of the cured coating film was measured with a Konig hardness tester under the same temperature and humidity conditions. The larger the measured value, the higher the hardness.

Examples 2-5
Water-dispersible polyisocyanate compositions (A) to (A-2), a hydroxyl group-containing acrylic resin emulsion (B-1), and a hydroxyl group-containing acrylic resin disper at the usage ratios shown in Tables (1) to (2). John (B-2), water-dispersed metal catalysts (C-1) to (C-4), and if necessary, deionized water are mixed, and the resin composition for water-based paints (D-2) of the present invention is mixed. To (D-5) were prepared. The working time of the resin composition for water-based paints and the cured coating film thereof were the same as in Example 1 except that the resin compositions for water-based paints (D-2) to (D-5) thus obtained were used. Appearance and initial hardness were evaluated. The evaluation results are shown in Tables (1) to (2).

Comparative Examples 1-3
In the usage ratio shown in Table 1 (2), the water-dispersible polyisocyanate composition (A), the hydroxyl group-containing acrylic resin emulsion (B-1), “Co-NAPHTHENATE 6%” (hereinafter abbreviated as cobalt naphthenate) The resin compositions (RD-1) to (RD-3) for comparative water-based paints were prepared by mixing deionized water as necessary. The pot life of the aqueous paint resin composition and its cured coating were the same as in Example 1 except that the comparative resin compositions for aqueous paint (RD-1) to (RD-3) thus obtained were used. The appearance and initial hardness of the film were evaluated. The evaluation results are shown in Table 1 (2).

Claims (10)

Water-dispersible polyisocyanate composition (A) containing hydrophobic polyisocyanate (a1), resin (B) having active hydrogen-containing groups capable of reacting with isocyanate groups and soluble or dispersible in water, water-dispersed metal A resin composition for water-based paints, comprising a catalyst (C) and water. The resin composition for water-based paints according to claim 1, wherein the water-dispersed metal catalyst (C) contains at least one metal selected from the group consisting of cobalt, zinc and zirconium. The resin composition for water-based paints according to claim 1, wherein the water-dispersed metal catalyst (C) contains a salt comprising at least one metal selected from the group consisting of cobalt, zinc and zirconium and a fatty acid. The resin composition for water-based paints according to claim 1, wherein the water-dispersed metal catalyst (C) is obtained by treating an organic metal catalyst with an emulsifier to disperse in water. The resin composition for water-based paint according to claim 1, 2 or 3, wherein the water-dispersible polyisocyanate composition (A) is a mixture of a hydrophobic polyisocyanate (a1) and a water-dispersible polyisocyanate (a2). object. The water-dispersible polyisocyanate composition (A) is a mixture of a hydrophobic polyisocyanate (a1), a vinyl polymer (a21) having an isocyanate group and a hydrophilic group, and a weight ratio (a1 / a21) thereof. ) Is 3/7 to 9.5 / 0.5. The resin composition for water-based paints according to claim 1, 2 or 3. The resin composition for water-based paints according to claim 1, wherein the resin (B) is a hydroxyl group-containing vinyl polymer. The hydroxyl group-containing vinyl polymer is obtained by solution polymerization of a vinyl monomer having a hydroxyl group, a vinyl monomer having a carboxyl group, and other vinyl monomers, and then neutralizing with a basic compound. The resin composition for water-based paints according to claim 7, which is a vinyl polymer obtained by emulsion polymerization of a vinyl polymer or a vinyl monomer having a hydroxyl group and another vinyl monomer. In the water-dispersed metal catalyst (C), the content of the metal component in the water-dispersed metal catalyst (C) is 0.005 to 5.0 weight with respect to 100 parts by weight of the solid content of the resin (B). The resin composition for water-based paints of Claims 1-8 contained in the range used as a part. The molar ratio (NCO / OH) of the isocyanate group (NCO) in the water-dispersible polyisocyanate composition (A) to the hydroxyl group (OH) in the resin (B) that can be dissolved or dispersed in water is 0.1 to 0.1. The resin composition for water-based paints according to claim 1, which is 5.