JP4559152B2 - Aqueous resin composition - Google Patents

Description

  The present invention relates to an aqueous resin composition capable of forming a coating film excellent in drying property, adhesion to a substrate, and anticorrosion, and an aqueous coating composition comprising the composition.

  In recent years, in the fields of paints, inks, adhesives, etc., from the viewpoint of resource saving, environmental hygiene, non-pollution, non-hazardous materials, etc., conversion from organic solvent type compositions to aqueous type compositions has been promoted. . For example, examples of the vehicle used in the aqueous coating composition include resins such as alkyd resins, acrylic resins, polyester resins, polyurethane resins, and epoxy resins. In these aqueous coating compositions, the alkyd resin can introduce an oxidative curing group into the resin skeleton by using an unsaturated fatty acid as a raw material, and the aqueous coating composition using the alkyd resin can be cured at one room temperature. In addition, because of its oiliness, corrosion resistance when applied to a metal surface can be expected, but its soft nature may delay the drying of the coating film. On the other hand, the acrylic resin is inferior in anticorrosion property although it is excellent in quick drying property and weather resistance. As an aqueous resin material having the characteristics of these two types of resins, many graft resins and the like for bonding alkyd resins and acrylic resins by chemical reaction have been developed and proposed. For example, Patent Document 1 discloses a fatty acid-modified monomer obtained by reacting a dry oil fatty acid or semi-dry oil fatty acid with an α, β-ethylenically unsaturated acid glycidyl ester using a surfactant and / or a polymer protective colloid. It is disclosed that an oxidative polymerization type aqueous emulsion is produced by emulsion polymerization of a monomer mixture containing a radically polymerizable monomer.

  By the way, the formation mechanism of the emulsion polymer is that the monomer diffuses in the water from the large monomer droplets in the aqueous phase, and the polymerization proceeds in the micelles made by the surfactant to produce polymer particles (polymerized small particles). It consists of to do. In this case, the monomer used for the polymerization must be supplied by diffusing water from the monomer droplets to the polymer particles under the conditions for polymerization.

  In general, there is a large particle size difference between monomer droplets and polymer particles growing from micelles. This means that there is a large difference between the total surface area of the monomer droplets and the total surface area of the polymer particles, so that the initiator radical and the monomer diffusing in water penetrate the larger surface area, that is, the polymer particles, The polymerization then proceeds. In the emulsion polymerization method, polymer particles grow while the particle diameter gradually increases.

  In the case of emulsion polymerization of a radically polymerizable monomer mixture containing the above fatty acid-modified monomer, the fatty acid-modified monomer having extremely poor solubility in water is left in the monomer droplets in the polymerization stage, and polymerization proceeds in the monomer droplets. Polymer particles containing a large amount of fatty acid-modified monomer units are formed, while monomers other than the fatty acid-modified monomer diffuse in water from the monomer droplets into the micelles, where the polymer contains many monomer units other than the fatty acid-modified monomer units. Since the particles are generated, there is a high possibility that the nonuniform distribution of the hydrophilic polymer particles and the hydrophobic polymer particles is extremely generated in the polymer particles in the finally obtained emulsion. Therefore, in the coating film formed from such an oxidation polymerization type aqueous emulsion, the hydrophobic polymer particles become nuclei and cause repelling, or the surface floats and remains sticky on the surface. Therefore, there is a problem that a transparent film cannot be formed and the finished appearance of the coating film is remarkably deteriorated.

  As a measure for overcoming the above problems, Patent Document 2 proposes an aqueous copolymer containing a copolymer that is a polymerization product of a vinyl monomer and a hydrophobic ester or a partial ester, and a method for producing the same. . In this publication, it is proposed to add a hydrophobic ester from a dry oil acid and a polyol to the monomer droplets in order to suppress the formation of second generation particles other than the monomer droplets during the polymerization. The water-based copolymer described in the publication forms a transparent film that does not contain a volatile coalescing aid. However, particularly in the initial stage after application, the drying property is slow, and the adhesive film remains practically sticky. There are drawbacks such as insufficient corrosion resistance of the formed coating film.

JP 59-8773 A JP 2000-319525 A

  The main object of the present invention is to provide an aqueous resin composition capable of forming a coating film excellent in adhesion to a substrate, corrosion resistance and water resistance even at room temperature.

  The present inventors have now completed the present invention with an aqueous resin composition containing an aqueous fatty acid-modified acrylic resin and an aqueous fatty acid-modified epoxy resin produced by a specific production method, and an aqueous coating composition containing the composition. It came.

Thus, the present invention
1. (A) The monomer mixture (I) containing the fatty acid-modified polymerizable unsaturated monomer (A1) and the other polymerizable unsaturated monomer (A2) is finely dispersed in an aqueous medium so that the average particle size is 500 nm or less, An aqueous fatty acid-modified acrylic resin produced by polymerizing the resulting monomer emulsion and an aqueous fatty acid-modified epoxy resin containing (B) fatty acid (b1) and epoxy resin (b2) having a weight average molecular weight of 200 or more as constituent units only including,
In the aqueous fatty acid-modified epoxy resin (B), the equivalent ratio of the fatty acid (b1) and the epoxy resin (b2) to the carboxyl group of the fatty acid (b1) and the epoxy group of the epoxy resin (b2) is 0.75: 1 to 1. It is obtained by making the fatty acid-modified epoxy resin (B1) obtained by reacting within the range of 25: 1 aqueous with an emulsifier, or
The fatty acid (b1) and the epoxy resin (b2) are reacted in an equivalent ratio of the carboxyl group of the fatty acid (b1) and the epoxy group of the epoxy resin (b2) in the range of 0.5: 1 to 1.3: 1. A fatty acid-modified epoxy resin containing a carboxyl group obtained by reacting a polymerizable unsaturated monomer (B2) containing a carboxyl group-containing polymerizable unsaturated monomer with the fatty acid-modified epoxy resin (B1) obtained by An aqueous resin composition obtained by adding water to make it water-soluble,
2. The aqueous resin composition according to 1, wherein the fatty acid-modified polymerizable unsaturated monomer (A1) is a reaction product of the fatty acid (a1) and the epoxy group-containing polymerizable unsaturated monomer (a2),
3. Item 3. The aqueous resin composition according to Item 1 or 2 , wherein the mixing ratio of the aqueous fatty acid-modified acrylic resin (A) and the aqueous fatty acid-modified epoxy resin (B) is in the range of 5/95 to 95/5 in terms of solid content weight ratio. object,
4). The aqueous resin composition according to any one of items 1 to 3 , further comprising a hydrazine derivative,
5.1 An aqueous coating composition comprising the aqueous resin composition according to any one of items 1 to 4 ;
6). A method for forming a coating film, which comprises applying the aqueous coating composition according to item 5 to a surface to be coated,
7). A coated article obtained by the method for forming a coating film according to item 6 ,
About.

  According to the aqueous resin composition of the present invention, the drying property and film forming property are good even under conditions of room temperature drying, excellent adhesion to the base material, and performance such as water resistance, durability, and corrosion resistance. Has a remarkable effect that an excellent coating film can be formed.

Fatty acid-modified polymerizable unsaturated monomer (A1)
The fatty acid-modified polymerizable unsaturated monomer (A1) used in the present invention can stably produce the aqueous fatty acid-modified acrylic resin (A), and is a coating film formed using the aqueous resin composition of the present invention. In the case of imparting adhesion to the composition and imparting oxidative curability to the composition of the present invention, an oxidative curing group can be introduced into the aqueous fatty acid-modified acrylic resin (A) particles, and a fatty acid-derived hydrocarbon. Polymerizable unsaturated monomers having a polymerizable unsaturated group at the end of the chain are included. Here, examples of the polymerizable unsaturated group include a vinyl group and a (meth) acryloyl group, and a (meth) acryloyl group is particularly preferable.

  Examples of the fatty acid-modified polymerizable unsaturated monomer (A1) include a reaction product of a fatty acid (a1) and an epoxy group-containing polymerizable unsaturated monomer (a2).

  Examples of the fatty acid (a1) include those having a structure in which a carboxyl group is bonded to the end of a hydrocarbon chain, and examples thereof include a dry oil fatty acid, a semi-dry oil fatty acid, and a non-dry oil fatty acid. Dry oil fatty acids and semi-dry oil fatty acids are not strictly distinguishable, but usually dry oil fatty acids are unsaturated fatty acids that are iodinated 130 or more, and semi-dry oil fatty acids are iodinated 100 or more and less than 130. Of unsaturated fatty acids. On the other hand, non-drying oil fatty acids are usually fatty acids having an iodine value of less than 100.

  Examples of the dry oil fatty acid and semi-dry oil fatty acid include fish oil fatty acid, dehydrated castor oil fatty acid, safflower oil fatty acid, linseed oil fatty acid, soybean oil fatty acid, sesame oil fatty acid, poppy oil fatty acid, eno oil fatty acid, hemp oil fatty acid, grape Nuclear oil fatty acid, corn oil fatty acid, tall oil fatty acid, sunflower oil fatty acid, cottonseed oil fatty acid, walnut oil fatty acid, rubber seed oil fatty acid, hydienoic acid fatty acid, etc., and non-drying oil fatty acid include, for example, coconut oil fatty acid , Hydrogenated coconut oil fatty acid, palm oil fatty acid and the like. These can be used alone or in combination of two or more. Furthermore, these fatty acids can be used in combination with caproic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid and the like.

  In the present invention, the fatty acid (a1) is preferably a dry oil fatty acid or a semi-dry oil fatty acid so as to impart oxidative curability to the formed coating film.

  The epoxy group-containing polymerizable unsaturated monomer (a2) that can be reacted with the fatty acid (a1) to produce the fatty acid-modified polymerizable unsaturated monomer (A1) is one epoxy group and one in one molecule. Specifically, for example, glycidyl (meth) acrylate, β-methyl glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 3,4- Examples thereof include epoxycyclohexylethyl (meth) acrylate, 3,4-epoxycyclohexylpropyl (meth) acrylate, and allyl glycidyl ether. These can be used alone or in combination of two or more.

  The fatty acid (a1) and the epoxy group-containing polymerizable unsaturated monomer (a2) have an equivalent ratio of a carboxyl group in the fatty acid (a1) and an epoxy group in the epoxy group-containing monomer (a2) of 0.75: 1 to 1. The reaction can be carried out in such a ratio that it is in the range of 1.25: 1, preferably 0.8: 1 to 1.2: 1.

  The reaction between the fatty acid (a1) and the epoxy group-containing polymerizable unsaturated monomer (a2) is usually carried out in the presence of a polymerization inhibitor without causing a problem such as gelation in the fatty acid component. The reaction can be carried out under conditions that allow the group and the epoxy group in the epoxy group-containing polymerizable unsaturated monomer to react smoothly, and is usually heated at a temperature of about 100 to about 180 ° C. for about 0.5 to about 10 hours. Is suitable.

  In this reaction, an esterification reaction catalyst such as a tertiary amine such as N, N-dimethylaminoethanol, a quaternary ammonium salt such as tetraethylammonium bromide or tetrabutylammonium bromide can be used. An inert organic solvent may be used.

  Examples of the polymerization inhibitor include hydroxy compounds such as hydroquinone, hydroquinone monomethyl ether, pyrocatechol and p-tert-butylcatechol; nitrobenzene, nitrobenzoic acid, o-, m- or p-dinitrobenzene, 2,4- Nitro compounds such as dinitrotoluene, 2,4-dinitrophenol, trinitrobenzene, and picric acid; quinone compounds such as p-benzoquinone, dichlorobenzoquinone, chloranil, anthraquinone, and phenanthroquinone; nitrosobenzene, nitroso-β-naphthol, and the like Examples thereof include radical polymerization inhibitors known per se such as nitroso compounds, and these can be used alone or in combination of two or more.

  The reaction product of the fatty acid (a1) and the epoxy group-containing polymerizable unsaturated monomer (a2) has a secondary hydroxyl group in the molecule, and is a coating film formed using the aqueous resin composition of the present invention. Adhesiveness can be improved, which is preferable.

  The fatty acid-modified polymerizable monomer (A1) can also be obtained by esterifying the fatty acid (a1) with the hydroxyl group-containing polymerizable unsaturated monomer (a3). Examples of the hydroxyl group-containing polymerizable unsaturated monomer (a3) include a compound having one hydroxyl group and one polymerizable unsaturated group in one molecule. Specifically, for example, 2-hydroxyethyl (meta C2-C8 hydroxyalkyl (meth) acrylate of (meth) acrylic acid such as acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, allyl alcohol -(Meth) acrylate having a hydroxyl group, such as an ε-caprolactone modified product of the above C2-C8 hydroxyalkyl (meth) acrylate; (meth) acrylate having a polyoxyethylene chain having a hydroxyl group at the molecular end, and the like. These can be used alone or in combination of two or more. .

  The fatty acid (a1) and the hydroxyl group-containing polymerizable unsaturated monomer (a3) usually have an equivalent ratio of 0.4: 1 to the carboxyl group in the fatty acid (a1) to the hydroxyl group in the hydroxyl group-containing monomer (a3). The reaction can be carried out in such a ratio that it is in the range of 1.25: 1, preferably 0.5: 1 to 1.2: 1.

  The reaction between the fatty acid (a1) and the hydroxyl group-containing polymerizable unsaturated monomer (a3) is usually carried out in the fatty acid (a1) component in the presence of a polymerization inhibitor without causing a reaction problem such as gelation. In the presence of an esterification catalyst at a temperature of about 100 to about 180 ° C. in the presence of an esterification catalyst. It is suitable to carry out by heating for 5 to about 10 hours. Examples of the esterification catalyst include sulfuric acid, aluminum sulfate, potassium hydrogen sulfate, alkyl-substituted benzene, hydrochloric acid, methyl sulfate, phosphoric acid, and the like. These catalysts usually contain the fatty acid (a1) to be reacted and a hydroxyl group. It can be used in the range of about 0.001 to about 2.0% by weight, based on the total amount of the polymerizable unsaturated monomer (a3). Furthermore, an organic solvent inert to the reaction can also be used.

  Examples of the polymerization inhibitor include hydroxy compounds such as hydroquinone, hydroquinone monomethyl ether, pyrocatechol and p-tert-butylcatechol; nitrobenzene, nitrobenzoic acid, o-, m- or p-dinitrobenzene, 2,4- Nitro compounds such as dinitrotoluene, 2,4-dinitrophenol, trinitrobenzene, and picric acid; quinone compounds such as p-benzoquinone, dichlorobenzoquinone, chloranil, anthraquinone, and phenanthroquinone; nitrosobenzene, nitroso-β-naphthol, and the like Examples thereof include radical polymerization inhibitors known per se such as nitroso compounds, and these can be used alone or in combination of two or more.

Other polymerizable unsaturated monomers (A2)
In the aqueous fatty acid-modified acrylic resin (A) in the present invention, the other polymerizable unsaturated monomer (A2) is a polymerizable unsaturated monomer copolymerizable with the fatty acid-modified polymerizable unsaturated monomer (A1), and is a molecule. Examples thereof include compounds containing one or more, preferably one polymerizable unsaturated group. Examples of the polymerizable unsaturated group include a vinyl group and a (meth) acryloyl group. Specific examples of the other polymerizable unsaturated monomer (A2) include methyl (meth) acrylate, ethyl (meth) acrylate, n -Propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-hexyl (meth) acrylate, octyl (meta ) Acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, tridecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, “isostearyl acrylate” (manufactured by Osaka Organic Chemical Co., Ltd.), cyclohexyl ( Meta) acryl Alkyl, cycloalkyl (meth) acrylate such as methylcyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, cyclododecyl (meth) acrylate; isobornyl group such as isobornyl (meth) acrylate Polymerizable unsaturated monomer; adamantyl group-containing polymerizable unsaturated monomer such as adamantyl (meth) acrylate; glycidyl (meth) acrylate, β-methylglycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 3 , 4-epoxycyclohexylethyl (meth) acrylate, 3,4-epoxycyclohexylpropyl (meth) acrylate, and other epoxy group-containing polymerizable unsaturated monomers such as allyl glycidyl ether; styrene, α-methylstyrene Aromatic vinyl monomers such as vinyl and toluene; vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, γ- (meth) acryloyloxypropyltrimethoxysilane, γ- (meth) acryloyloxypropyl Alkoxysilyl group-containing polymerizable unsaturated monomer such as triethoxysilane; siloxane macromonomer such as polydimethylsiloxane macromonomer; perfluoroalkyl such as perfluorobutylethyl (meth) acrylate and perfluorooctylethyl (meth) acrylate (meta ) Acrylate; alkyl fluorine group-containing polymerizable unsaturated monomer such as fluoroolefin; polymerizable unsaturated monomer having a photopolymerizable functional group such as maleimide group; N-vinylpyrrolidone, ethylene, Vinyl compounds such as tadiene, chloroprene, vinyl propionate and vinyl acetate; carboxyl group-containing polymerizable unsaturated monomers such as (meth) acrylic acid, fumaric acid, itaconic acid, maleic acid, crotonic acid and β-carboxyethyl acrylate; anhydrous Unsaturated carboxylic acid anhydrides such as maleic acid and itaconic anhydride; (meth) acrylonitrile, (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, dimethylaminoethyl (meth) acrylate, glycidyl (meth) acrylate and amines -Containing polymerizable unsaturated monomers such as adducts with 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, hydroxybutyl (meth) Acrylate Any (meth) acrylic acid having a hydroxyl group such as an alkyl (meth) acrylate having 2 to 8 carbon hydroxyl groups, an allyl alcohol, or an ε-caprolactone modified form of the above hydroxy (meth) acrylate having 2 to 8 carbon atoms. (Meth) acrylate; hydroxyl group-containing polymerizable unsaturated monomer such as (meth) acrylate having a polyoxyethylene chain having a hydroxyl group at the molecular end: (meth) acrylate having a polyoxyethylene chain having an alkoxy group at the molecular end; 2 -Sulphonic acid group-containing polymerizable unsaturated monomers such as acrylamido-2-methylpropane sulfonic acid, allyl sulfonic acid, styrene sulfonic acid sodium salt, sulfoethyl methacrylate and its sodium salt and ammonium salt; 2-hydroxy-4- (3 -Methacryloyloxy-2-hydroxy Propoxy) benzophenone, 2-hydroxy-4- (3-acryloyloxy-2-hydroxypropoxy) benzophenone, 2,2′-dihydroxy-4- (3-methacryloyloxy-2-hydroxypropoxy) benzophenone, 2,2′- Addition reaction formation of hydroxybenzophenones such as 2,4-dihydroxybenzophenone and 2,2 ', 4-trihydroxybenzophenone such as dihydroxy-4- (3-acryloxy-2-hydroxypropoxy) benzophenone and glycidyl (meth) acrylate Or a polymerizable unsaturated monomer having an ultraviolet-absorbing functional group such as 2- (2′-hydroxy-5′-methacryloyloxyethylphenyl) -2H-benzotriazole; 4- (meth) acryloyloxy-1,2 , 2,6,6- N-methylpiperidine, 4- (meth) acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-cyano-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 1- (Meth) acryloyl-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 1- (meth) acryloyl-4-cyano-4- (meth) acryloylamino-2,2,6 6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, 4-crotonoylamino-2,2,6,6-tetramethylpiperidine, 1-crotonoyl-4-crotonoyl Polymerizable unsaturated monomers having UV-stable functional groups such as oxy-2,2,6,6-tetramethylpiperidine; acrolein, dye Carbonyl group-containing polymerizable monomers such as seton acrylamide, diacetone methacrylamide, acetoacetoxyethyl methacrylate, formylstyrene, vinyl alkyl ketones having 4 to 7 carbon atoms (for example, vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone) Saturated monomer: allyl (meth) acrylate, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1,3- Butylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, 1,4-butanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6 -Hexanediol (meth) acrylate Pentaerythritol di (meth) acrylate, pentaerythritol tetra (meth) acrylate, glycerol di (meth) acrylate, 1,1,1-trishydroxymethylethanedi (meth) acrylate -1,1,1-trishydroxymethylethane tri (meth) acrylate, 1,1,1-trishydroxymethylpropane tri (meth) acrylate, triallyl isocyanurate, diallyl terephthalate And polyvinyl compounds having at least two polymerizable unsaturated groups in one molecule such as divinylbenzene, etc., and the like. These may be used alone or in combination of two or more according to the desired performance. .

  The use ratio of the monomer (A1) and the monomer (A2) is not particularly limited, and can be appropriately selected according to the performance and application desired for the target aqueous resin composition. , Based on the total amount of monomer (A1) and monomer (A2), monomer (A1) is in the range of 5-50 wt%, preferably 10-40 wt%, more preferably 10-35 wt%, and The monomer (A2) can be in the range of 50 to 95% by weight, preferably 60 to 90% by weight, and more preferably 65 to 90% by weight.

  In the present invention, the other polymerizable unsaturated monomer (A2) is an acid group-containing polymerizable unsaturated monomer (a4) based on the total weight of the monomer (A1) and the monomer (A2). It is desirable that it is contained within a range of 5% by weight, preferably 0.5% by weight or more and less than 3% by weight.

  Examples of the acid group-containing polymerizable unsaturated monomer (a4) include carboxyl group-containing polymerizable unsaturated monomers such as (meth) acrylic acid, maleic acid, crotonic acid, and β-carboxyethyl acrylate; 2-acrylamide-2- Examples include methylpropane sulfonic acid, allyl sulfonic acid, styrene sulfonic acid sodium salt, sulfoethyl methacrylate and sulfonic acid group-containing polymerizable unsaturated monomers such as sodium salt and ammonium salt thereof, and particularly acrylic acid, methacrylic acid A carboxyl group-containing polymerizable unsaturated monomer such as crotonic acid is preferred.

  Stability of aqueous fatty acid-modified acrylic resin (A) particles obtained in an aqueous medium by using acid group-containing polymerizable unsaturated monomer (a4) as at least a part of other polymerizable unsaturated monomer (A2) In addition, when the aqueous resin composition containing the same is applied to an enamel paint, the toning property of the paint can be improved.

  In addition, the other polymerizable unsaturated monomer (A2) is at least a part of the polymerizable unsaturated monomer containing a linear, branched or cyclic, saturated or unsaturated hydrocarbon group having 4 or more carbon atoms. The monomer (a5) is contained in the range of 30 to 90% by weight, preferably 35 to 85% by weight, more preferably 45 to 80% by weight, based on the total weight of the monomer (A1) and the monomer (A2). It is desirable that

  Examples of the polymerizable unsaturated monomer (a5) containing a linear, branched or cyclic, saturated or unsaturated hydrocarbon group having 4 or more carbon atoms include n-butyl (meth) acrylate and i-butyl. (Meth) acrylate, tert-butyl (meth) acrylate, n-hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, tridecyl (meth) acrylate, lauryl (meth) ) Acrylate, stearyl (meth) acrylate, “isostearyl acrylate” (manufactured by Osaka Organic Chemical Co., Ltd.), cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, Cyclododecyl (meth) acrylate, etc. Alkyl or cycloalkyl (meth) acrylate; isobornyl group-containing polymerizable unsaturated monomer such as isobornyl (meth) acrylate; adamantyl group-containing polymerizable unsaturated monomer such as adamantyl (meth) acrylate; styrene, α-methylstyrene, vinyltoluene And aromatic vinyl monomers. The use of the polymerizable unsaturated monomer (a5) having a hydrocarbon group having 4 or more carbon atoms can improve the water resistance of a coating film formed using the aqueous resin composition.

  In addition, the other polymerizable unsaturated monomer (A2) includes, as at least a part thereof, a polymerizable unsaturated monomer (a6) containing a linear or branched hydrocarbon group having 6 or more carbon atoms. It is desirable to contain 1 to 30% by weight, preferably 5 to 20% by weight, more preferably 6 to 18% by weight, based on the total weight of (A1) and monomer (A2).

  Examples of the polymerizable unsaturated monomer (a6) containing a linear or branched hydrocarbon group having 6 or more carbon atoms include n-hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl ( And (meth) acrylate, nonyl (meth) acrylate, tridecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, “isostearyl acrylate” (manufactured by Osaka Organic Chemical Co., Ltd.), etc. Or in combination of two or more.

  By using the polymerizable unsaturated monomer (a6) containing a linear or branched hydrocarbon group having 6 or more carbon atoms as at least a part of the other polymerizable unsaturated monomer (A2), aqueous Monomer emulsification after atomization of monomer mixture (I) containing fatty acid-modified polymerizable unsaturated monomer (A1) and other polymerizable unsaturated monomer (A2) in an aqueous medium in the production of fatty acid-modified acrylic resin (A) The polymerization stability of the product can be maintained, and the water resistance of the coating film formed using the aqueous resin composition can be improved.

  In the present invention, the other polymerizable unsaturated monomer (A2) is an acid group-containing polymerizable unsaturated monomer (a4) and a linear, branched or cyclic saturated or unsaturated hydrocarbon having 4 or more carbon atoms. A polymerizable unsaturated monomer (a5) containing a group, and a polymerizable unsaturated monomer (a7) other than the fatty acid-modified polymerizable unsaturated monomer (A1), the monomer (a4) and the monomer (a5). Comprising 5 to 50% by weight of monomer (A1), preferably 10 to 40% by weight, more preferably 10 to 35% by weight, based on the total weight of monomer (A1) and monomer (A2) 0.1 to 5% by weight of (a4), preferably 0.5 to 4.5% by weight, more preferably 0.5 to 3% by weight, and 45 to 80% by weight of monomer (a5), preferably 50 to 75 weight More preferably 55 to 70% by weight, and other polymerizable unsaturated monomer (a7) 0 to 49.9% by weight, preferably 0 to 39.5% by weight, more preferably 0 to 34.5% by weight. And the polymerizable unsaturated monomer (a5) containing a hydrocarbon group having 4 or more carbon atoms contains the above-mentioned linear or branched hydrocarbon group having 6 or more carbon atoms. Monomer (a6) is included in the range of 1 to 30% by weight, preferably 5 to 20% by weight, more preferably 6 to 18% by weight, based on the total weight of monomer (A1) and monomer (A2). It is desirable to become.

  The aqueous fatty acid-modified acrylic resin (A) can be stably produced by copolymerizing the above-mentioned specific proportion of the fatty acid-modified polymerizable unsaturated monomer (A1) and other polymerizable unsaturated monomer (A2). Further, there is a transparency of the coating film formed using the aqueous resin composition, and performances such as water resistance and anticorrosion can be improved.

  In addition, the other polymerizable unsaturated monomer (A2) preferably includes the cycloalkyl group-containing polymerizable unsaturated monomer (a8) as at least a part thereof. As the cycloalkyl group-containing polymerizable unsaturated monomer (a8), a compound having one cycloalkyl group having 6 or more carbon atoms and one polymerizable unsaturated bond in one molecule is preferable. Examples thereof include cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, cyclododecyl (meth) acrylate, and the like. These can be used in combination. Of these, cyclohexyl (meth) acrylate is preferred.

  A coating formed using an aqueous resin composition by using at least a part of the other polymerizable unsaturated monomer (A2) containing the cycloalkyl group-containing polymerizable unsaturated monomer (a8). The weather resistance of the film can be improved, and the water resistance and stain resistance can also be improved. The content in the case of improving the weather resistance is 1 to 70% by weight, preferably 10 to 60% by weight based on the total weight of the monomer (A1) and the monomer (A2). is there.

  In addition, the other polymerizable unsaturated monomer (A2) desirably contains an aromatic vinyl monomer (a9) as at least a part thereof. As an aromatic vinyl monomer (a9), vinyl aromatic compounds, such as styrene, (alpha) -methylstyrene, vinyl toluene, can be mentioned, for example, These can be used individually or in combination of 2 or more types. By using such an aromatic vinyl monomer (a9), the copolymerizability of the monomer (A1) and the monomer (A2) can be increased, the amount of unreacted monomers can be minimized, and water-resistant coating such as water resistance can be formed. The physical properties of the film can be improved.

  The aromatic vinyl monomer (a9) is generally 1 to 50% by weight, preferably 5 to 45% by weight, more preferably 12 to 35% by weight, based on the total weight of the monomer (A1) and the monomer (A2). It is preferable to use within the range of%.

  In addition, the other polymerizable unsaturated monomer (A2) preferably includes the carbonyl group-containing polymerizable unsaturated monomer (a10) as at least a part thereof.

  The carbonyl group-containing polymerizable unsaturated monomer (a10) includes a compound having one carbonyl group and one polymerizable unsaturated bond in one molecule, and specifically includes, for example, acrolein, diacetone acrylamide. , Diacetone methacrylamide, acetoacetoxyethyl methacrylate, formylstyrene, vinyl alkyl ketones having 4 to 7 carbon atoms (for example, vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone) and the like. Or it can use in combination of 2 or more types. Of these, diacetone (meth) acrylamide is particularly preferred.

  By using at least a part of the other polymerizable unsaturated monomer (A2) that contains the carbonyl group-containing polymerizable unsaturated monomer (a10) and blending a hydrazine derivative described later, a carbonyl group and hydrazine It is possible to proceed with crosslinking with the derivative, to further improve the drying property of the coating film, and to prepare a coating composition that forms a coating film having excellent physical properties such as weather resistance and water resistance. it can.

  Such carbonyl group-containing polymerizable unsaturated monomer (a10) is generally 0.1 to 35% by weight, preferably 0.5 to 20% by weight, based on the total weight of monomer (A1) and monomer (A2). It is suitable to use within the range.

  In addition, the other polymerizable unsaturated monomer (A2) is a hydroxyl group-containing polymerizable unsaturated monomer (a11) in order to ensure the stability of the particles in the polymerization stage or storage stage of the aqueous fatty acid-modified acrylic resin (A). It can also comprise. Examples of the hydroxyl group-containing polymerizable unsaturated monomer (a11) include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) acrylate. Hydroxyl groups such as alkyl (meth) acrylates having 2 to 8 carbon atoms of (meth) acrylic acid, allyl alcohols, and ε-caprolactone modified products of hydroxy (meth) acrylates having 2 to 8 carbon atoms, such as (Meth) acrylates having (meth) acrylates having a polyoxyethylene chain whose molecular end is a hydroxyl group, and the use ratio thereof is generally based on the total amount of the monomer (A) and the monomer (B). 1 to 50% by weight, preferably 1 to 30% by weight.

Aqueous fatty acid-modified acrylic resin (A)
In the present invention, the monomer mixture (I) contains the fatty acid-modified polymerizable unsaturated monomer (A1) and the other polymerizable unsaturated monomer (A2) as essential components, and is further substantially polymerizable unsaturated group. The compound which does not contain can also be contained. Thereby, the aqueous | water-based fatty acid modified acrylic resin (A) particle | grains can also include the compound which does not contain this polymerizable unsaturated group substantially.

  Examples of such a compound that does not substantially contain a polymerizable unsaturated group include paint additives such as UV absorbers, UV stabilizers and metal dryers; acrylic resins, polyester resins, polyurethane resins, alkyd resins, polyorganosiloxanes. Resins such as pigments; colorants such as pigments and dyes.

  When the monomer mixture (I) is finely dispersed in an aqueous medium, an emulsifier may be used in combination as necessary. As the emulsifier, an anionic emulsifier and a nonionic emulsifier are suitable. Examples of the anionic emulsifier include sodium salts and ammonium salts such as alkylsulfonic acid, alkylbenzenesulfonic acid, and alkylphosphoric acid. Nonionic emulsifiers include, for example, polyoxyethylene oleyl ether, polyoxyethylene stearyl ether, polyoxyethylene lauryl ether, polyoxyethylene tridecyl ether, polyoxyethylene phenyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene octyl Phenyl ether, polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene monooleate, sorbitan monolaurate, sorbitan monos Areto, sorbitan monostearate, sorbitan trioleate, polyoxyethylene sorbitan monolaurate, and the like.

  Also, a polyoxyalkylene group-containing anionic emulsifier having an anionic group and a polyoxyalkylene group such as a polyoxyethylene group or a polyoxypropylene group in one molecule, or the anionic group and polymerizable unsaturated in one molecule Reactive anionic emulsifiers having groups may be used.

  The emulsifier can be used in the range of 0.1 to 15% by weight, preferably 0.5 to 12% by weight, based on the total amount of all monomers used.

  The monomer mixture (I) may contain a chain transfer agent for the purpose of adjusting the molecular weight of the resulting aqueous fatty acid-modified acrylic resin (A). Examples of the chain transfer agent include compounds having a mercapto group. Specifically, for example, lauryl mercaptan, t-dodecyl mercaptan, octyl mercaptan, 2-ethylhexyl thioglycolate, 2-methyl-5-tert- Examples thereof include butylthiophenol, mercaptoethanol, thioglycerol, mercaptoacetic acid (thioglycolic acid), mercaptopropionate, and n-octyl-3-mercaptopropionate. In general, the chain transfer agent is preferably used in an amount of 0.05 to 10% by weight, particularly 0.1 to 5% by weight, based on the total amount of all monomers.

  The aqueous fatty acid-modified acrylic resin (A) can be stably produced by the fatty acid-modified polymerizable unsaturated monomer (A1) and the like, which can suppress the diffusion of the monomer (A2) in the polymerization stage. If necessary, the monomer mixture (I) may be blended with a hydrophobic organic solvent generally used in miniemulsion polymerization such as a long-chain saturated hydrocarbon solvent such as hexadecane or a long-chain alcohol solvent such as hexadecanol. May be.

  The monomer mixture (I) described above is a particle dispersion that is a particle dispersion containing the fatty acid-modified polymerizable unsaturated monomer (A1) and the other polymerizable unsaturated monomer (A2) by being finely dispersed in an aqueous medium. Product (hereinafter sometimes abbreviated as “monomer emulsion”) is formed.

  Examples of the aqueous medium include water or a water-organic solvent mixed solution obtained by mixing water with an organic solvent such as a water-soluble organic solvent.

  The concentration of the monomer mixture (I) in the aqueous medium is generally 10 to 70 from the viewpoint of atomization suitability of the monomer emulsion to be formed, stability in the polymerization stage, practicality when applied to an aqueous paint, and the like. It is suitable within the range of wt%, preferably 20-60 wt%.

  The fine dispersion of the monomer mixture (I) in the aqueous medium is not particularly limited, and can be usually performed using a disperser having a high energy shearing ability. Examples of the disperser that can be used in this case include a high-pressure emulsifier, an ultrasonic emulsifier, a high-pressure colloid mill, and a high-pressure homogenizer. These dispersers can usually be operated under a high pressure of about 10 to 1000 MPa, preferably about 50 to 300 MPa. In addition, the monomer mixture (I) may be pre-emulsified with a disper or the like in advance before being dispersed by the machine.

  The average particle diameter of the dispersed particles in the monomer emulsion obtained by finely dispersing the monomer mixture (I) in the aqueous medium by the above method is 500 nm or less from the viewpoint of the transparency of the formed coating film, water resistance, and the like. The range of 80 to 400 nm is preferable, and the range of 100 to 300 nm is more preferable. If it exceeds 500 nm, the polymerization stability of the monomer emulsion and the transparency of the coating film formed using the aqueous resin composition of the present invention become insufficient, which is not preferable.

  In this specification, the average particle size is “SALD-3100” (trade name, manufactured by Shimadzu Corporation, laser diffraction particle size distribution analyzer), and the sample is diluted with deionized water to 20 ° C. The average particle size of the emulsion or resin dispersion of the atomized monomer mixture (I) is measured at 30 minutes after the production, respectively.

  In the polymerization of the monomer emulsion thus obtained, for example, in accordance with the mini-emulsion polymerization method, all the monomer emulsion after fine dispersion is charged into a reactor equipped with a stirrer, a polymerization initiator is added, and the mixture is heated while stirring. Can be performed.

  The polymerization initiator may be either oil-soluble or water-soluble, and examples of the oil-soluble polymerization initiator include benzoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide. Organic peroxides such as oxides; azo compounds such as azobisisobutyronitrile and azobis (2,4-dimethylvaleronitrile); and water-soluble initiators such as cumene hydroperoxide , Organic peroxides such as tert-butyl peroxide, tert-butyl peroxylaurate, tert-butyl peroxyisopropyl carbonate, tert-butyl peroxyacetate, diisopropylbenzene hydroperoxide; azobis (2-methylpropiononitrile) A Bis (2-methylbutyronitrile), 4,4′-azobis (4-cyanobutanoic acid), dimethylazobis (2-methylpropionate), azobis [2-methyl-N- (2-hydroxyethyl)- Azo compounds such as propionamide] and azobis {2-methyl-N- [2- (1-hydroxybutyl)]-propionamide}; and persulfates such as potassium persulfate, ammonium persulfate, and sodium persulfate. . These can be used alone or in combination of two or more. Further, if necessary, a reducing agent such as sugar, sodium formaldehyde sulfoxylate, or iron complex may be used in combination with the polymerization initiator to form a redox polymerization system.

  In general, the polymerization initiator is preferably used in an amount of 0.1 to 5% by weight, particularly 0.2 to 3% by weight, based on the total weight of the monomer (A1) and the monomer (A2). The method for adding the polymerization initiator is not particularly limited, and can be appropriately selected according to the type and amount thereof. For example, it may be previously contained in the monomer mixture (I) or the aqueous medium, or may be added all at once during the polymerization, or may be dropped.

  In the present invention, in order to improve the mechanical stability of the particles of the obtained aqueous fatty acid-modified acrylic resin (A), when the aqueous fatty acid-modified acrylic resin (A) has an acidic group, it is neutralized. It is desirable to neutralize with an agent. The neutralizing agent is not particularly limited as long as it can neutralize acidic groups. For example, sodium hydroxide, potassium hydroxide, trimethylamine, dimethylaminoethanol, 2-methyl-2-amino-1-propanol, Examples thereof include triethylamine and aqueous ammonia, and these neutralizing agents are desirably used in such an amount that the pH of the aqueous resin dispersion after neutralization is about 6.5 to 9.0.

  The aqueous fatty acid-modified acrylic resin (A) obtained by the above production method can be produced stably, and the average particle size of the dispersion resin can be 500 nm or less, particularly within the range of 100 to 300 nm. In addition, the oil length of the aqueous fatty acid-modified acrylic resin (A) is 0.5 to 45%, preferably 3 to 35%, more preferably 10 to 35% in terms of finish of the formed coating film and corrosion resistance. The inside is preferable. In this specification, the oil length is the weight percentage of fatty acid to resin solids.

Water-based fatty acid-modified epoxy resin (B)
In the present invention, the aqueous fatty acid-modified epoxy resin (B) is an aqueous resin containing fatty acid (b1) and an epoxy resin (b2) having a weight average molecular weight of 200 or more as constituent units, and the average particle size of the dispersion resin is 100 to 100. Those in the range of 1000 nm, particularly 100 to 800 nm, more particularly 100 to 500 nm are preferred.

  In the present specification, the weight average molecular weight is a value obtained by converting the weight average molecular weight measured by gel permeation chromatography using tetrahydrofuran as a solvent based on the weight average molecular weight of polystyrene. Columns used in the gel permeation chromatography are “TSKgel G-4000H × L”, “TSKgel G-3000H × L”, “TSKgel G-2500H × L”, “TSKgel G-2000H × L” (all Tosoh Corporation).

  In addition, the oil length of the aqueous fatty acid-modified epoxy resin (B) is 0.5 to 300%, preferably 5 to 200%, more preferably 8 to 180%, from the viewpoint of the finish of the formed coating film and the corrosion resistance. The range of is preferable.

  As said fatty acid (b1), it can select from the illustration of the fatty acid (a1) used for the said aqueous | water-based fatty acid modified acrylic resin (A) suitably, and can use it.

  The epoxy resin (b2) is a resin having one or more, preferably two, epoxy groups in the molecule and a weight average molecular weight of 200 or more. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin In addition, a polyphenol such as bisphenol A / F type epoxy resin or novolac type phenol resin is reacted with an epihalohydrin such as epichlorohydrin to introduce a glycidyl group, or this glycidyl group introduction reaction product is further reacted with a polyphenol. An aromatic epoxy resin having an increased molecular weight; an epoxy resin such as an aliphatic epoxy resin or an alicyclic epoxy resin; an epoxy group-containing polymerizable unsaturated monomer and another polymerizable unsaturated monomer are copolymerized Epoxy group-containing acrylic copolymer; epoxy group Polybutadiene resin having; polyurethane resin having an epoxy group.

  The said epoxy resin can be used individually or in combination of 2 or more types according to the objective, respectively. Particularly suitable epoxy resins include aromatic epoxy resins.

  The epoxy resin (b2) is generally an epoxy having a weight average molecular weight in the range of 200 to 6000, in particular 300 to 2000, more particularly 350 to 2000, and generally in the range of 100 to 3000, in particular 150 to 1000, more particularly 175 to 1000. It is preferable to have an equivalent weight.

  The aqueous fatty acid-modified epoxy resin (B) is preferably obtained by making the fatty acid-modified epoxy resin (B1) obtained by reacting the fatty acid (b1) and the epoxy resin (b2) aqueous. .

  In the fatty acid-modified epoxy resin (B1), the use ratio of the fatty acid (b1) and the epoxy resin (b2) is such that the equivalent ratio of the carboxyl group of the fatty acid (b1) to the epoxy group of the epoxy resin (b2) is 0.75. : 1 to 1.25: 1, preferably 0.8: 1 to 1.2: 1.

  The reaction between the fatty acid (b1) and the epoxy resin (b2) is usually carried out in the presence of a polymerization inhibitor without causing problems such as gelation and the carboxyl group in the fatty acid (b1) and the epoxy resin. (B2) can be carried out under conditions that allow the epoxy group to react smoothly, and is usually suitable by heating at a temperature of about 140 to about 170 ° C. for about 7 to about 15 hours. .

  In this reaction, an esterification reaction catalyst such as a tertiary amine such as N, N-dimethylaminoethanol, a quaternary ammonium salt such as tetraethylammonium bromide or tetrabutylammonium bromide can be used. An inert organic solvent may be used.

  Examples of the polymerization inhibitor include hydroxy compounds such as hydroquinone, hydroquinone monomethyl ether, pyrocatechol and p-tert-butylcatechol; nitrobenzene, nitrobenzoic acid, o-, m- or p-dinitrobenzene, 2,4- Nitro compounds such as dinitrotoluene, 2,4-dinitrophenol, trinitrobenzene, and picric acid; quinone compounds such as p-benzoquinone, dichlorobenzoquinone, chloranil, anthraquinone, and phenanthroquinone; nitrosobenzene, nitroso-β-naphthol, and the like Examples thereof include radical polymerization inhibitors known per se such as nitroso compounds, and these can be used alone or in combination of two or more.

  The method of making the fatty acid-modified epoxy resin (B1) aqueous is not particularly limited, but a method of mixing an emulsifier with the fatty acid-modified epoxy resin (B1) and dispersing it in an aqueous medium, the fatty acid-modified epoxy. When resin (B1) has a carboxyl group, after neutralizing this carboxyl group with a basic substance, the method of disperse | distributing in an aqueous medium, etc. are mentioned.

  The emulsifier can be appropriately selected from those listed in the description of the aqueous fatty acid-modified acrylic resin (A). As a compounding quantity, 0.1-15 weight% with respect to resin (B1) solid content, Preferably it is 0.1-10 weight%, More preferably, the inside of the range of 0.5-5 weight% is suitable.

  The aqueous fatty acid-modified epoxy resin (B) is obtained by reacting a polymerizable unsaturated monomer (B2) with a fatty acid-modified epoxy resin (B1) obtained by reacting a fatty acid (b1) and an epoxy resin (b2). It may be obtained by making the resin aqueous.

  In the fatty acid-modified epoxy resin (B1) before reacting with the polymerizable unsaturated monomer (B2), the use ratio of the fatty acid (b1) and the epoxy resin (b2) is the carboxyl group of the fatty acid (b1) and the epoxy resin ( It is preferred that the equivalent ratio of b2) to the epoxy group is in the range of 0.5: 1 to 1.3: 1, preferably 0.5: 1 to 1.2: 1.

  The polymerizable unsaturated monomer (B2) can be appropriately selected from those exemplified in the description of the polymerizable unsaturated monomer (A2) in the aqueous fatty acid-modified acrylic resin (A).

  In the polymerizable unsaturated monomer (B2), the polymerizable unsaturated monomer (B2) preferably includes an aromatic vinyl monomer. As the aromatic vinyl monomer, the same aromatic vinyl monomer (a9) as that described above can be used, and the use ratio thereof is generally 1 to 50% by weight in the polymerizable unsaturated monomer (B2), preferably 4 -45 wt%, more preferably 12-35 wt% is preferred.

  The polymerizable unsaturated monomer (B2) preferably comprises a carbonyl group-containing polymerizable unsaturated monomer. The carbonyl group-containing polymerizable unsaturated monomer can be the same as the carbonyl group-containing polymerizable unsaturated monomer (a10), and the use ratio thereof is generally 0% in the polymerizable unsaturated monomer (B2). Desirably, it is within the range of 1-35 wt%, preferably 0.5-20 wt%.

  The polymerizable unsaturated monomer (B2) preferably contains a hydroxyl group-containing polymerizable unsaturated monomer. As such a hydroxyl group-containing polymerizable unsaturated monomer, those similar to the hydroxyl group-containing polymerizable unsaturated monomer (a11) can be used, and the use ratio thereof is 1 in the polymerizable unsaturated monomer (B2). It is desirable to be within the range of ˜50% by weight, preferably 1 to 30% by weight.

  In the present invention, the reaction between the fatty acid-modified epoxy resin (B1) and the polymerizable unsaturated monomer (B2) is performed by, for example, mixing the fatty acid-modified epoxy resin (B1), the polymerizable unsaturated monomer (B2), the polymerization initiator, and the like. And it can carry out by carrying out a heating reaction within about 60-150 degreeC normally for about 1 to 10 hours. In this case, the use ratio of the fatty acid-modified epoxy resin (B1) and the polymerizable unsaturated monomer (B2) is such that the polymerizable unsaturated monomer (B2) is 10 to 2000 weight per 100 parts by weight of the fatty acid-modified epoxy resin (B1). Part, preferably 25 to 1000 parts by weight.

  As the polymerization initiator, conventionally known polymerization initiators can be used, but radicals are generated in the fatty acid-modified epoxy resin (B1) molecule by hydrogen abstraction, so that grafting with the polymerizable unsaturated monomer (B2) proceeds efficiently. In order to achieve this, it is desirable to use a peroxide polymerization initiator. Examples of the peroxide-based polymerization initiator include benzoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, and the like. Among these, benzoyl peroxide is preferable.

  Further, in order to efficiently advance the reaction between the fatty acid-modified epoxy resin (B1) and the polymerizable unsaturated monomer (B2), the fatty acid-modified epoxy resin (B1) has an epoxy group, and the polymerizable unsaturated monomer (B2) has Each of them may contain a carboxyl group-containing polymerizable unsaturated monomer. Examples of the polymerizable unsaturated monomer having a carboxyl group include (meth) acrylic acid, fumaric acid, itaconic acid, maleic acid, crotonic acid, β-carboxyethyl acrylate and the like. In the polymerizable unsaturated monomer (B2), It is desirable to contain 0.5 to 20% by weight, preferably 1 to 15% by weight. When the polymerizable unsaturated monomer (B2) contains a carboxyl group-containing polymerizable unsaturated monomer, water dispersibility or pigment dispersibility can be improved, which is preferable.

  In the esterification reaction, the reaction can be carried out by heating for about 1 to 10 hours under the conditions of 120 ° C. to 150 ° C. in the presence of an epoxy group / carboxyl group reaction catalyst. Examples of epoxy group / carboxyl group reaction catalysts include quaternary salt catalysts such as tetraethylammonium bromide, tetrabutylammonium bromide, tetraethylammonium chloride, tetrabutylphosphonium bromide, triphenylbenzylphosphonium chloride; triethylamine, tributylamine And the like.

  In the reaction between the fatty acid-modified epoxy resin (B1) and the polymerizable unsaturated monomer (B2), the order of the grafting reaction by hydrogen abstraction and the esterification reaction by epoxy group / carboxyl group can be selected as appropriate, and they are performed simultaneously. It is also possible.

  The method for making the fatty acid-modified epoxy resin modified with the polymerizable unsaturated monomer (B2) aqueous is not particularly limited, and is a method in which an emulsifier is mixed with the fatty acid-modified epoxy resin and dispersed in an aqueous medium. In the case where the fatty acid-modified epoxy resin has a carboxyl group, a method in which the carboxyl group is neutralized with a basic substance and then dispersed in an aqueous medium can be used. Moreover, the organic solvent in a system can also be distilled off and removed as needed after making it aqueous.

Aqueous resin composition The aqueous resin composition of the present invention contains the aqueous fatty acid-modified acrylic resin (A) and the aqueous fatty acid-modified epoxy resin (B) as base resin components, and the blending ratio thereof is strictly limited. It can be changed according to the use of the resin composition, but from the viewpoint of the dryness and anticorrosion of the formed coating film, the resin (A) / resin (B) solid content weight ratio, Generally, it can be in the range of 5/95 to 95/5, preferably 10/90 to 90/10.

  In addition to this, the aqueous resin composition of the present invention preferably further contains a hydrazine derivative. Specific examples of the derivatives include saturated carboxylic acid dihydrazides having 2 to 18 carbon atoms such as oxalic acid dihydrazide, malonic acid dihydrazide, glutaric acid dihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, and the like. Monoolefinic unsaturated dicarboxylic acid dihydrazide such as maleic acid dihydrazide, fumaric acid dihydrazide, itaconic acid dihydrazide; phthalic acid dihydrazide, terephthalic acid dihydrazide or isophthalic acid dihydrazide, pyromellitic acid dihydrazide, trihydrazide or tetrahydrazide; Citric acid trihydrazide, 1,2,4-benzenetrihydrazide, ethylenediaminetetraacetic acid tetrahydrazide, 1,4,5,8-naphthoic acid tetrahydride A polyhydrazide obtained by reacting a low polymer having a carboxylic acid lower alkyl ester group with hydrazine or a hydrazine hydrate (hydrazine hydride); a compound having a hydrazide group such as dihydrazide carbonate; a bissemicarbazide; hexamethylene diisocyanate or isophorone A polyfunctional semicarbazide obtained by excessively reacting a diisocyanate such as diisocyanate and a polyisocyanate compound derived therefrom with an N, N-substituted hydrazine such as N, N-dimethylhydrazine or the hydrazide exemplified above; The dihydrazide exemplified above is excessively reacted with an isocyanate group in a reaction product of a polyether and an active hydrogen compound containing a hydrophilic group such as polyols and polyethylene glycol monoalkyl ethers. Resulting aqueous polyfunctional semicarbazide; compound having a semicarbazide group, such as a mixture of polyfunctional semicarbazide and aqueous polyfunctional semicarbazide, compounds and the like having a hydrazone group such as bis-acetyl-di hydrazone.

  By containing the hydrazine derivative, the formed coating film is useful because it can adsorb and remove harmful substances in the air, such as formaldehyde, and is also useful. When B) has a carbonyl group, it can act as a crosslinking agent for crosslinking.

  The blending amount of the hydrazine derivative is 0.01 to 10% by weight, particularly 0.1 to 5%, based on the total resin solid content of the aqueous fatty acid-modified acrylic resin (A) and the aqueous fatty acid-modified epoxy resin (B). It is desirable to be in the range of wt%.

  Moreover, the said aqueous resin composition can also contain a metal dryer as a catalyst for promoting oxidative hardening. Examples of the metal dryer include a salt of at least one metal selected from the group consisting of aluminum, calcium, cerium, cobalt, iron, lithium, magnesium, manganese, zinc, and zirconium, and an acid. Examples include capric acid, caprylic acid, isodecanoic acid, linolenic acid, naphthenic acid, neodecanoic acid, octenoic acid, oleic acid, palmitic acid, resin acid, ricinoleic acid, soybean oil fatty acid, stearic acid, tall oil fatty acid and the like. It is done. The blending amount of the metal dryer is 0.01 to 10% by weight, particularly 0.1 to 10% by weight, based on the total resin solid content of the aqueous fatty acid-modified acrylic resin (A) and the aqueous fatty acid-modified epoxy resin (B). A range of 5% by weight is desirable.

  In addition to the above components, the aqueous resin composition includes water-soluble or emulsion-type alkyd resins, silicone resins, fluorine resins, epoxy resins, urethane resins, polyester resins, amino resins, and other modified resins; wetting agents, antifoaming agents Additives such as plasticizers, film-forming aids, organic solvents, thickeners, preservatives, fungicides, pH adjusters, curing catalysts, and surface adjusters can be appropriately selected and combined.

  Thus, the above-mentioned aqueous resin composition is used for coatings such as automotive outer panels, automotive parts, automotive repairs, cans, PCMs, architectural coatings, printing inks, non-woven fabrics, etc. It can be used for various applications such as an agent, a filler, a molding material, and a resist.

Aqueous coating composition The aqueous coating composition of the present invention comprises the aqueous resin composition described above.

  When the aqueous resin composition is applied to an aqueous coating composition, it can be applied to either a clear coating or an enamel coating.

  When applied as an enamel paint, conventionally known color pigments, glitter pigments, extender pigments, rust preventive pigments, and the like can be blended as the pigment component.

  The blending amount of the pigment is preferably in the range of 5 to 45%, particularly 10 to 40%, more particularly 14 to 38% in terms of pigment volume concentration. Here, the “pigment volume concentration” is a volume ratio of the pigment content in the total solid content of the total resin content and the total pigment content in the paint. In this specification, the specific gravity of the pigment which is the basis for calculating the volume of the pigment is according to “Paint Raw Material Handbook 6th Edition” (Japan Paint Manufacturers Association), and the specific gravity of the resin solids is Approximate to 1.

  Although the water-based coating composition of the present invention is not particularly limited, since the familiarity of the fatty acid component of the aqueous fatty acid-modified acrylic resin (A) and the aqueous fatty acid-modified epoxy resin (B) to the iron surface is good, iron It is suitable as an undercoat for painted surfaces on substrates or iron substrates.

  When used as such an undercoat paint, it is desirable to blend a rust preventive pigment as the pigment, and it is desirable to use a phosphoric acid pigment as the rust preventive pigment. The phosphoric acid pigment is desirably dispersible easily in the presence of a polymer surfactant from the viewpoint of corrosion resistance and gloss. Specific examples of the phosphate pigment include, for example, zinc phosphate, phosphorous zinc silicate, aluminum zinc phosphate, calcium zinc phosphate, calcium phosphate, aluminum pyrophosphate, calcium pyrophosphate, aluminum dihydrogen triphosphate, metaphosphoric acid Examples thereof include aluminum, calcium metaphosphate, zinc phosphomolybdate, and aluminum phosphomolybdate.

  The aqueous coating composition preferably contains at least one compound selected from the group consisting of nitrites, phytates, tannates, polyphosphates and polyamine compounds. Examples of the nitrite include sodium nitrite, calcium nitrite, strontium nitrite, barium nitrite, and ammonium nitrite.Examples of the phytate include sodium phytate and potassium phytate. Examples of the tannate include sodium tannate and potassium tannate. Examples of the polyamine compound include N- (2-hydroxyethyl) ethylenediaminetriacetic acid (HEDTA), ethylenediaminetetraacetic acid (EDTA), and diethylenetriamine. Pentaacetic acid (DTPA), propylenediaminetetraacetic acid (PDTA), iminodiacetic acid, nitrilotriacetic acid (NTA), diethylenetriaminepentamethylenephosphonic acid (DTPMP), and alkali metal salts thereof; monoalkylamines and Riamin, intercalation compounds and the like formed by intercalating the like layered phosphate and quaternary ammonium ion such as dihydrogen tripolyphosphate aluminum. These can be used alone or in combination of two or more. The compounding amount of the above compound is 0.01 to 10% by weight, particularly 0.02 to 5%, based on the total resin solid content of the aqueous fatty acid-modified acrylic resin (A) and the aqueous fatty acid-modified epoxy resin (B). It is desirable to be in the range of wt%.

  In the aqueous coating composition, pigment dispersant, surfactant, surface conditioner, plasticizer, anti-settling agent, antistatic agent, antibacterial agent, fragrance, ultraviolet absorber, ultraviolet stabilizer, curing catalyst, dispersant, Antifoaming agent, thickener, film-forming aid, preservative, antifungal agent, antifreezing agent, pH adjuster, flash last inhibitor, aldehyde scavenger, layered viscosity mineral, powdered or fine particle activated carbon, photocatalyst Additives such as titanium dioxide and low-contaminating agents such as alkylene glycol-modified alkyl silicate can be appropriately selected and contained in combination.

  The aqueous coating composition can be applied using a method such as roller, air spray, airless spray, lysine gun, universal gun, brush, electrostatic coating, or the like. Moreover, as a drying method, any of heat drying, forced drying, and normal temperature drying may be sufficient. In the present specification, the drying condition of less than 40 ° C. is normal temperature drying, the drying condition of 40 ° C. or more and less than 80 ° C. is forced drying, and the drying condition of 80 ° C. or more is heat drying.

  Hereinafter, the present invention will be described more specifically with reference to examples. “Parts” and “%” are “parts by weight” and “% by weight”.

Production of fatty acid-modified polymerizable unsaturated monomer Production Example 1
The following components were put into a reaction vessel and reacted at a reaction temperature of 140 ° C. for 5 hours while stirring to obtain a fatty acid-modified polymerizable unsaturated monomer (a-1).
Flaxseed oil fatty acid 280 parts Glycidyl methacrylate 142 parts.

Production of aqueous fatty acid-modified acrylic resin Production Example 2
The following components are put into a glass beaker and stirred at 2000 rpm for 15 minutes with a disper to produce a pre-emulsified liquid. Then, the pre-emulsified liquid is pressurized at 100 MPa with a high-pressure emulsifier that applies high-pressure energy to collide the fluids. By processing, a monomer emulsion having an average particle size of dispersed particles of 190 nm was obtained.
Monomer emulsion composition Fatty acid-modified polymerizable unsaturated monomer (a-1) 30 parts n-butyl methacrylate 5 parts i-butyl methacrylate 18 parts t-butyl methacrylate 13 parts 2-ethylhexyl methacrylate 7 parts cyclohexyl methacrylate 20 parts 2-hydroxyethyl methacrylate 5 parts methacrylic acid 2 parts "Newcol 707SF" (Note 1) 3 parts deionized water 145 parts The monomer emulsion is then transferred to a flask so that the solids concentration is 45% with deionized water. Diluted. Thereafter, the temperature was raised to 85 ° C., and an initiator aqueous solution in which 0.5 part of ammonium persulfate was dissolved in 13 parts of deionized water was added to the flask, and stirred for 3 hours while maintaining the temperature. Thereafter, an initiator aqueous solution in which 0.25 part of ammonium persulfate was dissolved in 10 parts of deionized water was added to the flask, stirred for 1 hour while maintaining the temperature, cooled to 40 ° C., and adjusted to pH with dimethylaminoethanol. The aqueous fatty acid-modified acrylic resin (A-1) having a solid content concentration of 40% and an average particle size of the dispersed resin of 190 nm was obtained by adjusting to 8.0.
(Note 1) “Newcol 707SF”: trade name, manufactured by Nippon Emulsifier Co., Ltd., an anionic emulsifier having a polyoxyethylene chain, 30% active ingredient.

Production Examples 3-8
Aqueous fatty acid-modified acrylic resins (A-2) to (A-7) were obtained in the same manner as in Production Example 2 except that the composition of the monomer emulsion was changed as shown in Table 1.
Production Example 9
Production Example 2 except that the pre-emulsified liquid obtained in Production Example 2 was stirred at 10,000 rpm for 5 minutes using a disperser having high shearing ability to obtain a monomer emulsion having an average particle diameter of dispersed particles of 520 nm. In the same composition and procedure as in No. 2, an aqueous fatty acid-modified acrylic resin (A-8) having an average particle size of the dispersion resin of 630 nm was produced.

Production of aqueous fatty acid-modified epoxy resin Production Example 10
Into a reaction vessel, 280 parts of linseed oil fatty acid, 185 parts of “Epicoat 828” (Note 2) and 0.23 part of tetraethylammonium bromide were added and reacted at a reaction temperature of 140 ° C. with stirring to obtain a fatty acid-modified epoxy resin. The reaction between epoxy groups and carboxyl groups was monitored by measuring the amount of residual carboxyl groups. The reaction was continued until the amount of residual carboxyl groups was almost eliminated, and it took about 7 hours until the reaction was completed. Thereafter, 19 parts of “Newcol 707SF” was put into the reaction vessel, and 620 parts of deionized water was dropped while stirring at 2000 rpm with a disper to obtain an aqueous fatty acid-modified epoxy resin (B-1) having a solid content of 40%. It was.
(Note 2) “Epicoat 828”: trade name, manufactured by Japan Epoxy Resin, liquid bisphenol A type epoxy resin, epoxy equivalent 185
Production Examples 11-14
Aqueous fatty acid-modified epoxy resins (B-2) to (B-5) were produced in the same manner as in Production Example 10 except that the composition was changed as shown in Table 2.

(Note 3) “Epicoat 1001”: trade name, manufactured by Japan Epoxy Resin, solid bisphenol A type epoxy resin, epoxy equivalent of 450 to 500
(Note 4) “EP-4080E”: trade name, manufactured by Asahi Denka Kogyo Co., Ltd., hydrogenated bisphenol A, epoxy equivalent 240
(Note 5) “Epicron HP-820”: trade name, manufactured by Dainippon Ink, Inc., epichlorohydrin adduct of alkyldiphenol, epoxy equivalent 220.

Production of fatty acid-modified epoxy resin before being modified with acrylic Production Example 15
Into a reaction vessel, 280 parts of linseed oil fatty acid, 185 parts of “Epicoat 828” (Note 2) and 0.23 part of tetraethylammonium bromide were allowed to react with stirring at a reaction temperature of 140 ° C. for 7 hours. C-1) was produced.
Production Examples 16-20
Fatty acid-modified epoxy resins (C-2) to (C-6) were produced in the same manner as in Production Example 15 except that the composition was changed as shown in Table 3. For Production Examples 19 and 20, the amount of epoxy groups was calculated by monitoring the amount of residual carboxyl groups, and the reaction was carried out until the amount of epoxy groups reached the value in the table.

Production of fatty acid-modified epoxy resin modified with acrylic Production Example 21
43 parts of the fatty acid-modified epoxy resin (C-1) obtained in Production Example 15 and 18 parts of ethylene glycol monobutyl ether were heated to 140 ° C. under a nitrogen stream, and the polymerizable unsaturated monomer and polymerization initiator shown below. And the solvent mixture was added dropwise over 3 hours, followed by aging for 2 hours. After completion of the reaction, after cooling to room temperature, 4 parts of dimethylaminoethanol was added, and 255 parts of deionized water was added dropwise with stirring, and modified with acrylic having a non-volatile content of 30% and an average particle size of the dispersed resin of 180 nm. An aqueous fatty acid-modified epoxy resin (D-1) was obtained.
Styrene 40 parts n-butyl acrylate 20 parts t-butyl methacrylate 20 parts 2-ethylhexyl methacrylate 6 parts methyl methacrylate 5 parts 2-hydroxyethyl methacrylate 5 parts methacrylic acid 4 parts t-butylperoxy-2-ethylhexanoate 8 parts 42 parts of ethylene glycol monobutyl ether.

Production Examples 22 to 27
Aqueous fatty acid-modified epoxy resins (D-2) to (D-7) modified with acrylic were obtained in the same manner as in Production Example 21 except that the composition was changed as shown in Table 4.

(Note 6) “Caprolactone methacryl 3X”: trade name, manufactured by Daicel Chemical Industries, ε-caprolactone-modified hydroxyethyl methacrylate, active ingredient 80%.

Production Example 28
43 parts of the fatty acid-modified epoxy resin (C-5) obtained in Production Example 19 and 18 parts of ethylene glycol monobutyl ether were heated to 140 ° C. under a nitrogen stream, and a mixture of the following polymerizable unsaturated monomer and polymerization initiator: Was dropped in 3 hours, and aged for 2 hours after dropping. Next, 0.05 part of tetraethylammonium bromide was added, and the reaction was carried out for about 2 hours. After the reaction was completed, the reaction mixture was cooled to room temperature, 4 parts of dimethylaminoethanol was added, and 255 parts of deionized water was added dropwise with stirring. An aqueous fatty acid-modified epoxy resin (D-8) having a content of 30% and an average particle size of 110 nm was obtained.
Styrene 15 parts n-butyl acrylate 15 parts i-butyl methacrylate 20.2 parts t-butyl methacrylate 20 parts 2-ethylhexyl methacrylate 15 parts 2-hydroxyethyl methacrylate 5 parts methacrylic acid 9.8 parts t-butyl peroxy-2- Ethylhexanoate 8 parts Ethylene glycol monobutyl ether 45 parts Production Example 29
An aqueous fatty acid-modified epoxy resin (D-9) was obtained in the same manner as in Production Example 28 except that the formulation in Production Example 28 was changed as shown in Table 4.

Production of aqueous coating composition Example 1
The following components were sequentially charged in a container and stirred with a disper for 30 minutes until uniform, to obtain a pigment paste having the following composition. Thereafter, 201.4 parts of the pigment paste were charged with 175 parts of 40% aqueous fatty acid-modified acrylic resin (A-1) and 75 parts of 30% aqueous fatty acid-modified epoxy resin (B-1), and “DICnate 1000W” (Note 9) 3.2 parts, 0.25 parts adipic acid dihydrazide, 15 parts “TEXANOL” (Note 10), 2 parts “SN Deformer 380” (Note 11), 2 parts “Adecanol UH-438” (Note 12) and nitrous acid 0.5 parts of sodium were sequentially mixed to obtain an aqueous coating composition.
Pigment paste composition Water supply 40 parts Ethylene glycol 2 parts "Sulaoff 72N" (Note 13) 0.8 parts "Nopcosanto K" (Note 14) 2 parts "Adecanol UH-438" (Note 12) 0.8 Part "JR-600A" (Note 15) 60 parts "Sunlight SL-1500" (Note 16) 50 parts "LF Bowsey P-W-2" (Note 17) 45 parts "SN Deformer 380" (Note 11) 0 .8 parts.

Examples 2 to 21 and Comparative Examples 1 to 3
In Example 1 above, each aqueous coating composition was produced in the same manner as in Example 1 except that the composition was changed to Table 5 below.

(Note 7) “CD540”: trade name, manufactured by Dainippon Ink & Chemicals, Inc., acrylic-modified epoxy ester aqueous dispersion (fatty acid adduct), solid content 40%
(Note 8) “Phthalkid W790”: trade name, manufactured by Hitachi Chemical, acrylic-modified epoxy ester aqueous dispersion (fatty acid adduct), solid content 39%
(Note 9) “DICnate 1000W”: trade name, manufactured by Dainippon Ink and Chemicals, metal dryer, Co content 3.6%
(Note 10) “TEXANOL”; trade name, manufactured by Eastman Chemical Co., Ltd., 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, film-forming aid (Note 11) “SN deformer 380”: Product name, manufactured by San Nopco, defoaming agent (Note 12) “Adecanol UH-438”: Product name, manufactured by Adeka Co., Ltd., thickener (Note 13) “Suraoff 72N”: Product name, manufactured by Takeda Pharmaceutical Co., Ltd. Preservative (Note 14) “Nopco Santo K”: trade name, manufactured by San Nopco, pigment dispersant (Note 15) “JR-600A”: trade name, manufactured by Teica, titanium white, specific gravity 4.1
(Note 16) “Sunlight SL-1500”: trade name, manufactured by Takehara Chemical Co., Ltd., Tancal, specific gravity 2.7
(Note 17) “LF Bow PW-2”: trade name, manufactured by Kikuchi Color Co., Ltd., zinc phosphate anticorrosive pigment, specific gravity 3.5.

Performance Evaluation Each water-based coating composition obtained in Examples 1 to 21 and Comparative Examples 1 to 3 was evaluated according to the following criteria. The results are shown in Table 5.
(* 1) Water resistance:
A steel plate (150 × 70 × 0.8 mm) specified in JIS K 5410 is degreased with xylene, and further, each of the aqueous coating compositions is diluted to about 70 KU with clean water, and the coating amount is 150 g / b with a brush. Each test coating plate was obtained by coating to m ² and drying for 1 week under conditions of an air temperature of 20 ° C. and a relative humidity of 60%. Each test coated plate was subjected to a water resistance test (96 hours immersion) according to JIS K 5400 8.19. Each coated surface after the test was evaluated according to the following criteria.
○: No swelling of the coating film Δ: Slight swelling of the coating film is observed ×: Swelling is observed on the entire coating surface (* 2) Drying property Drying property of the test coating plate obtained in the same manner as the above (* 1) Was evaluated according to the following criteria.
○: very good, Δ: good, ×: poor.
(* 3) Corrosion protection:
A steel plate (150 x 70 x 0.8 mm) specified in JIS K 5410 is used as a raw material, degreased with xylene, and each water-based paint is diluted to about 70 KU with tap water, and applied with a brush. It was painted in such a way as to provide 100g / ^{m 2.} Further, after the first drying, the second coating was performed in the same manner as the first coating, and each test coating plate was prepared by drying for 7 days under conditions of an air temperature of 20 ° C. and a relative humidity of 60%. These were subjected to 36 cycles of the combined cycle anti-corrosion resistance test specified in JIS K 5621, and the coating surface was evaluated according to the following criteria.
○: No rust is observed in the coating film △: Some rust is observed in the coating film,
X: Rust is recognized on the entire surface of the coating film.

Claims (7)

(A) The monomer mixture (I) containing the fatty acid-modified polymerizable unsaturated monomer (A1) and the other polymerizable unsaturated monomer (A2) is finely dispersed in an aqueous medium so that the average particle size is 500 nm or less, An aqueous fatty acid-modified acrylic resin produced by polymerizing the resulting monomer emulsion and an aqueous fatty acid-modified epoxy resin containing (B) fatty acid (b1) and epoxy resin (b2) having a weight average molecular weight of 200 or more as constituent units only including,
In the aqueous fatty acid-modified epoxy resin (B), the equivalent ratio of the fatty acid (b1) and the epoxy resin (b2) to the carboxyl group of the fatty acid (b1) and the epoxy group of the epoxy resin (b2) is 0.75: 1 to 1. It is obtained by making the fatty acid-modified epoxy resin (B1) obtained by reacting within the range of 25: 1 aqueous with an emulsifier, or
The fatty acid (b1) and the epoxy resin (b2) are reacted in an equivalent ratio of the carboxyl group of the fatty acid (b1) and the epoxy group of the epoxy resin (b2) in the range of 0.5: 1 to 1.3: 1. A fatty acid-modified epoxy resin containing a carboxyl group obtained by reacting a polymerizable unsaturated monomer (B2) containing a carboxyl group-containing polymerizable unsaturated monomer with the fatty acid-modified epoxy resin (B1) obtained by An aqueous resin composition obtained by adding water to make it aqueous. The aqueous resin composition according to claim 1, wherein the fatty acid-modified polymerizable unsaturated monomer (A1) is a reaction product of the fatty acid (a1) and the epoxy group-containing polymerizable unsaturated monomer (a2). The aqueous resin composition according to claim 1 or 2 , wherein the mixing ratio of the aqueous fatty acid-modified acrylic resin (A) and the aqueous fatty acid-modified epoxy resin (B) is in the range of 5/95 to 95/5 in terms of solid content weight ratio. object. The aqueous resin composition according to any one of claims 1 to 3 , further comprising a hydrazine derivative. An aqueous coating composition comprising the aqueous resin composition according to any one of claims 1 to 4 . A method of forming a coating film, comprising applying the aqueous coating composition according to claim 5 to a surface to be coated. The coated article obtained by the coating-film formation method of Claim 6 .