JP6766355B2 - Method for manufacturing aqueous resin composition and coating - Google Patents

Description

This onset bright relates to a process for the preparation of a manufacturing method and a coated product which has been coated with the aqueous resin composition of the aqueous resin composition.

In recent years, in the field of paints, the conversion from organic solvent-based paints to water-based paints has been attempted from the viewpoints of environmental protection and safety and health.
For example, Patent Document 1 discloses an aqueous epoxy resin coating material containing a copolymer of a macromonomer and a polymerizable unsaturated monomer having a nonionic hydrophilic group. Further, Patent Document 2 discloses a self-emulsifying aqueous resin composition composed of a polymer containing a specific macropolyol and an aqueous coating material containing a curing agent.

International Publication No. 12/033226 International Publication No. 13/157479

However, the storage stability of the aqueous resin compositions described in Patent Documents 1 and 2 was insufficient. In addition, the aqueous resin composition has a high viscosity, which may limit the method of use and use thereof.
An object of the present invention is to provide an aqueous resin composition having a low viscosity and excellent storage stability, a method for producing the same, and a coated material coated with such an aqueous resin composition.

The present invention is an organic solvent containing 60% by mass or more of an organic solvent having a solubility parameter SP value of 8.50 (cal / cm ³ ) ^1/2 or less and a solubility in water of 3 g / 100 g or more by the Polymers method. (I) is a method for producing an aqueous resin composition, which comprises a step of polymerizing a radically polymerizable monomer in the presence of an α-methylstyrene dimer to produce a polymer (II), wherein the polymer ( In the step of producing II), the radically polymerizable monomer (A) containing the hydroxyl group-containing radically polymerizable monomer (a) is polymerized in the organic solvent (I) in the presence of the α-methylstyrene dimer. The step (1) for obtaining a dispersion liquid containing the polymer (P) and the radical polymerizable monomer (B) containing the carboxyl group-containing radical monomer (b) in the dispersion liquid containing the polymer (P). ) Is polymerized to obtain a dispersion liquid containing the polymer (Q), which is a method for producing an aqueous resin composition .

The aqueous resin composition of the present invention (hereinafter referred to as the present composition) has a low viscosity and excellent storage stability. Further, according to the method for producing an aqueous resin composition according to the present invention, an aqueous resin composition having a low viscosity and excellent storage stability can be produced.

[Organic solvent]
The organic solvent (I), which is a component of the present composition, contains 60% by mass or more of an organic solvent having a solubility parameter SP value of 10.00 (cal / cm ³ ) ^1/2 or less according to the Fedors method.
By containing 60% by mass or more of an organic solvent having an SP value of 10.00 (cal / cm ³ ) ^1/2 or less, the storage stability of the present composition is improved. The SP value of an organic solvent having an SP value of 10.00 (cal / cm ³ ) ^1/2 or less is preferably 9.50 (cal / cm ³ ) ^1/2 or less, preferably 9.00 (cal / cm ³ ) ^{1 /. 2} or less is more preferable, and 8.50 (cal / cm ³ ) ^1/2 or less is particularly preferable. The content ratio of the organic solvent having an SP value of 10.00 (cal / cm ³ ) ^1/2 or less in all the organic solvents is preferably 70% by mass or more, more preferably 80% by mass or more, and 90% by mass. The above is particularly preferable. The solubility parameter SP value is a value calculated by the Fedors method (Robert F. Fedors, Polymer Engineering and Science, 14, 147-154 (1974)), and can be calculated by using the following formula (1). it can.
δ = (E / V) ^1/2 (1)
In the formula (1), δ represents the SP value, E represents the aggregation energy (cal / mol), and V represents the molar volume (cm ³ / mol).

Further, it is preferable that the organic solvent (I) contains 60% by mass or more of the organic solvent having a solubility in water at 20 ° C. of 1 g / 100 g or more because the viscosity of the obtained aqueous resin composition can be kept low. .. The solubility of an organic solvent in water at 20 ° C. of 1 g / 100 g or more is preferably 3 g / 100 g or more, and more preferably 9 g / 100 g or more. The content ratio of the organic solvent of 1 g / 100 g or more is more preferably 70% by mass or more, further preferably 80% by mass or more, and particularly preferably 90% by mass or more.

A preferable compound as an organic solvent having an SP value of 10.00 (cal / cm ³ ) ^1/2 or less is, for example, propylene glycol dimethyl ether (SP value: 7.53, solubility in water at 20 ° C.: 44 g / 100 g). , Ethylene glycol dimethyl ether (SP value: 7.63, solubility in water at 20 ° C.: ∞ / 100 g), Dipropylene glycol dimethyl ether (SP value: 7.88, solubility in water at 20 ° C.: 53 g / 100 g), Tripropylene glycol dimethyl ether (SP value 8.07, solubility in water at 20 ° C.: 24 g / 100 g), diethylene glycol dimethyl ether (SP value: 8.10, solubility in water at 20 ° C.: ∞ / 100 g), diethylene glycol diethyl ether Ether-based solvents such as (SP value: 8.18, solubility in water at 20 ° C.: ∞ / 100 g), triethylene glycol dimethyl ether (SP value: 8.37, solubility in water at 20 ° C.: ∞ / 100 g) Dipropylene glycol monomethyl ether acetate (SP value: 8.71, solubility in water at 20 ° C.: 19 g / 100 g), propylene glycol monomethyl ether acetate (SP value: 8.73, solubility in water at 20 ° C.: 1) .6 g / 100 g), diethylene glycol monoethyl ether acetate (SP value: 9.00, solubility in water at 20 ° C: ∞ g / 100 g), propylene glycol diacetate (SP value: 9.60, to water at 20 ° C) Solubility: 8 g / 100 g) and the like, acetate-based solvents and the like can be mentioned. As the organic solvent having an SP value of 10.00 (cal / cm ³ ) ^1/2 or less, one type may be used alone or two or more types may be used in combination.

The content of the organic solvent (I) in the present composition is preferably 1 to 50 parts by mass, and 5 to 35 parts by mass with respect to 100 parts by mass of the polymer (II) from the viewpoint of storage stability, environmental protection, and safety and health. Parts by mass are more preferred.

[Polymer (II)]
The polymer (II), which is a component of the present composition, is a polymer obtained by polymerizing a radically polymerizable monomer and contains a structure derived from α-methylstyrene dimer.

α-Methylstyrene dimer α-methylstyrene dimer (2,4-diphenyl-4-methyl-1-pentene; hereinafter, sometimes referred to as “MSD”) is known as an add-square root chain transfer agent (2,4-diphenyl-4-methyl-1-pentene; hereinafter referred to as “MSD”). Japanese Unexamined Patent Publication No. 7-2954). When a radically polymerizable monomer is polymerized in the presence of MSD, a polymer having an unsaturated group derived from MSD at the terminal is obtained. When a radically polymerizable monomer is polymerized in the presence of this polymer, a polymer in which a polymer chain composed of this monomer is grafted can be obtained. Since the polymer thus obtained contains a structure derived from MSD, it can be used as the polymer (II).

Radically polymerizable monomer polymer (II) has a purpose of reacting with a curing agent to be described later, from the viewpoint of storage stability of the composition, and preferably has a hydroxyl group. The hydroxyl group can be introduced by copolymerizing the hydroxyl group-containing radically polymerizable monomer (a). Specific examples of the hydroxyl group-containing radically polymerizable monomer (a) include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl. Examples thereof include (meth) acrylate, 1-methyl-4-hydroxybutyl (meth) acrylate, 1-methyl-4-hydroxypentyl (meth) acrylate, and allyl glycol. These can be used alone or in combination of two or more.

The amount of the hydroxyl group-containing radically polymerizable monomer (a) used is preferably 5 to 50% by mass with respect to the total amount of the monomers used as the raw material of the polymer (II). If it is 5% by mass or more, the obtained aqueous resin composition is excellent in storage stability, and if it is 50% by mass or less, the obtained coating film is excellent in water resistance and moisture resistance. More preferably, it is 7 to 45% by mass, and most preferably 10 to 40% by mass.

Further, from the viewpoint of storage stability, it is preferable to copolymerize the carboxyl group-containing radically polymerizable monomer (b). Specific examples of the carboxyl group-containing radically polymerizable monomer (b) include methacrylic acid, acrylic acid, fumaric acid, itaconic acid, maleic acid, crotonic acid, vinyl benzoic acid, maleic acid monobutyl ester, and itaconic acid. Examples thereof include monomethyl ester and itaconic acid butyl ester. These can be used alone or in combination of two or more.

The amount of the carboxyl group-containing radically polymerizable monomer (b) used is preferably 0.5 to 5% by mass with respect to the total amount of the monomers used as the raw material of the polymer (II). If it is 0.5% by mass or more, the obtained aqueous resin composition is excellent in storage stability, and if it is 5% by mass or less, the obtained coating film is excellent in water resistance and moisture resistance. More preferably, it is 0.5 to 3% by mass.

Examples of the radically polymerizable monomer (c) other than the monomers (a) and (b) that can be used as a raw material for the polymer (II) include methyl (meth) acrylate, ethyl (meth) acrylate, and n-. Butyl (meth) acrylate, iso-butyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, etc. Alkyl (meth) acrylates having an alkyl group having 1 to 18 carbon atoms; styrene derivatives such as styrene, vinyltoluene and α-methylstyrene; ethylenically unsaturated nitriles such as acrylonitrile and methacrylonitrile; N-methoxy N-alkoxy substituted amides such as methyl acrylamide, N-ethoxymethyl acrylamide, N-butoxymethyl acrylamide; glycidyl (meth) acrylate, β-methylglycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, Epoxy group-containing ethylenically unsaturated monomers such as 3,4-epoxycyclohexylethyl (meth) acrylate, 3,4-epoxycyclohexylpropyl (meth) acrylate, and allylglycidyl ether, dimethylaminoethyl (meth) acrylate, diethylamino. Examples thereof include ethylenically unsaturated basic monomers such as ethyl (meth) acrylate. These can be used alone or in combination of two or more. Further, from the viewpoint of storage stability of the obtained aqueous resin composition, it is preferable to contain epoxy group-containing ethylenically unsaturated monomers. The amount of the epoxy group-containing ethylenically unsaturated monomer used is preferably 0.01 to 1% by mass, preferably 0.01 to 0.5, based on the total amount of the monomers used as the raw material of the polymer (II). The mass% is more preferable, and 0.01 to 0.2% by mass is particularly preferable.

Polymerization Step The polymer (II) of the present invention can be produced by a known polymerization method such as a solution polymerization method, a massive polymerization method, an emulsion polymerization method, etc. Among them, a solution using an organic solvent (I) as a solvent. It is preferably produced by a polymerization method.
Further, the polymerization step of the polymer (II) preferably includes the following steps (1) and (2).

<Process (1)>
A step of obtaining a dispersion liquid containing a polymer (P) obtained by polymerizing a radically polymerizable monomer (A) in an organic solvent (I).

<Process (2)>
A step of polymerizing a radically polymerizable monomer (B) in a dispersion containing the polymer (P) to obtain a dispersion containing the polymer (Q).

The polymerization of step (1) is preferably carried out in the presence of MSD. The presence of MSD gives a polymer (P) having an unsaturated group derived from MSD at the end. When the polymerization of the step (2) is carried out using this polymer (P), the polymer (II) obtained by grafting the polymer (Q) onto the polymer (P) is obtained, and thus the aqueous resin composition is stored. The stability can be further improved.

Further, from the viewpoint of storage stability of the aqueous resin composition, the radically polymerizable monomer (A) contains a hydroxyl group-containing radical polymerizable monomer (a) and an epoxy group-containing ethylenically unsaturated monomer. , The radically polymerizable monomer (B) preferably contains a carboxyl group-containing radical monomer (b). By doing so, an epoxy group is introduced into the polymer (P) and a carboxyl group is introduced into the polymer (Q). Therefore, the reaction between the epoxy group and the carboxyl group causes the polymer (P) to be heavily weighted. Since the polymer (II) obtained by grafting the coalescence (Q) is obtained, the storage stability of the aqueous resin composition can be further improved.

The reaction temperature at the time of polymerization in the presence of MSD in the step (1) is preferably in the range of 110 ° C. to 200 ° C. from the viewpoint of the reaction efficiency of MSD and the like. The polymerization time is usually preferably 1 hour to 10 hours, more preferably 1 hour to 6 hours.

The weight average molecular weight polymer (II) preferably has a weight average molecular weight of 3,000 to 100,000, more preferably 3,000 to 50,000, and even more preferably 5,000 to 20,000. The larger the weight average molecular weight, the better the obtained coating film has various durability such as water resistance, moisture resistance, weather resistance, solvent resistance, etc., and the smaller the weight average molecular weight, the better the dispersibility in water, and the obtained coating film has high gloss. ..

In the present specification, the weight average molecular weight of the polymer (II) means the weight average molecular weight measured under the following conditions by using the tetrahydrofuran-soluble component as a polystyrene-equivalent value by the GPC method.
Measuring device: High-speed GPC device HLC-8320 manufactured by Tosoh Corporation
Column: Made by Tosoh Corporation, TSKgelSuper HZM-M, HZM-M, HZ2000
Oven temperature: 40 ° C
Eluent: tetrahydrofuran Sample concentration: 0.3% by weight
Flow rate: 0.35 mL / min Injection volume: 10 μL

As the initiator , those generally used for radical polymerization can be used, for example, azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 2,2'. Oils such as -azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile Soluble azo compounds; 2,2'-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2,2'-azobis {2-methyl-N -[2- (1-Hydroxyethyl)] propionamide}, 2,2'-azobis {2-methyl-N- [2- (1-hydroxybutyl)] propionamide}, 2,2'-azobis [2 -(5-Methyl-2-imidazolin-2-yl) propane] and its salts, 2,2'-azobis [2- (2-imidazolin-2-yl) propane] and its salts, 2,2'-azobis [2- (3,4,5,6-tetrahydropyrimidine-2-yl) propane] and its salts, 2,2'-azobis (1-imino-1-pyrrolidino-2-methylpropane) and its salts, 2 , 2'-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} and its salts, 2,2'-azobis (2-methylpropionamidine) and its salts, 2 , 2'-Azobisisobuty [N- (2-carboxyethyl) -2-methylpropionamidine] and its salts and other water-soluble azo compounds; benzoyl peroxide, cumenehydroperoxide, t-butylhydroperoxide, t-butyl Examples thereof include organic peroxides such as peroxy-2-ethylhexanoate and t-butylperoxyisobutyrate, and persulfates such as potassium persulfate, sodium persulfate and ammonium persulfate. These can be used alone or in combination of two or more.

Other chain transfer agents When adjusting the molecular weight, mercaptans other than MSD such as n-dodecyl mercaptan, t-dodecyl mercaptan, n-octyl mercaptan, n-tetradecyl mercaptan, and n-hexyl mercaptan are used as molecular weight modifiers. Known chain transfer agents such as halogen compounds such as carbon tetrachloride and ethylene bromide can also be used, and these can be used alone or in combination of two or more.

[Water dispersion process]
As a method for obtaining the aqueous resin composition of the present invention from a polymer solution containing an organic solvent (I) and a polymer (II) obtained by solution polymerization or the like, all of the carboxyl groups contained in the polymer (II) or It is preferable that a part thereof is neutralized with a basic compound and then water is added to disperse in water, or a polymer solution neutralized in water is added and dispersed in water. It is also possible to add a polymer solution to water containing a basic compound and disperse it.

Examples of the basic compound used for neutralizing the carboxyl group of the polymer (II) include ammonia, triethylamine, propylamine, dibutylamine, amylamine, 1-aminooctane, 2-dimethylaminoethanol, ethylaminoethanol and 2-. Diethylaminoethanol, 1-amino-2-propanol, 2-amino-1-propanol, 2-amino-2-methyl-1-propanol, 3-amino-1-propanol, 1-dimethylamino-2-propanol, 3- Examples thereof include dimethylamino-1-propanol, 2-propylaminoethanol, ethoxypropylamine, aminobenzyl alcohol, morpholin, sodium hydroxide and potassium hydroxide. These can be used alone or in combination of two or more.

The amount of the basic compound used is such that the degree of neutralization, that is, the molar ratio of the basic compound to the carboxyl group is 40 to 150%, preferably 60 to 120%, and more preferably 80 to 110%.

The temperature at the time of water dispersion is preferably 90 ° C. or lower, more preferably 80 ° C. or lower, from the viewpoint of storage stability of the obtained aqueous resin composition.

[Other combinations]
When the polymer (II) has a hydroxyl group, the present composition may contain a cross-linking agent having a cross-linking property with the hydroxyl group. By blending the cross-linking agent, it is possible to obtain a coating film having excellent durability such as water resistance, moisture resistance, weather resistance and solvent resistance. Examples of the cross-linking agent include melamine-based, isocyanate-based, carbodiimide-based, oxazoline-based, and epoxy-based compounds. From the viewpoint of stability and the like, melamine-based and isocyanate-based cross-linking agents are preferable. The amount of the cross-linking agent used is preferably in the range where the equivalent of the cross-linking compound such as isocyanate is 0.3 to 2 equivalents with respect to 1 equivalent of the hydroxyl group contained in the polymer (II). More preferably, it is 0.5 to 1.1 equivalents.

Furthermore, from the viewpoint of exhibiting excellent performance as a coating material, this composition contains various pigments, antifoaming agents, pigment dispersants, leveling agents, anti-dripping agents, matting agents, ultraviolet absorbers, light stabilizers, etc. Various additives such as antioxidants, heat resistance improvers, slip agents, preservatives, plasticizers, and film-forming aids may be blended.

Further, the present composition contains other water-dispersible resins such as polyester-based resin, polyurethane-based resin, acrylic-based resin, acrylic silicone-based resin, silicone-based resin, fluorine-based resin, and epoxy-based resin, and water-soluble resins. You may.

[Painted material]
The water-based resin composition of the present invention is suitable as a water-based coating material, and can be coated on various base materials to obtain a coated product. Examples of the base material include metal base materials such as iron and aluminum, organic base materials such as various plastics, and inorganic substrates such as glass and cement mortar.

As a method of applying the present composition to the surface of various substrates, for example, various coating methods such as a spray coating method, a roller coating method, a bar coating method, an air knife coating method, a brush coating method, and a dipping method can be appropriately selected. it can.

After coating, a coating film can be obtained by drying at room temperature or heating and drying at room temperature or higher and 200 ° C. or lower.

Examples of the present invention are shown below. In addition, "part" in this Example means "part by mass".
[Example 1]
The following organic solvent is charged in a flask equipped with a stirrer, a reflux condenser, a temperature control device and a dropping pump, the internal temperature of the flask is raised to 120 ° C., and then the following contains a monomer, an initiator and a chain transfer agent. The first mixture was added dropwise over 3 hours. The internal temperature was maintained at 120 ° C. during the dropping.

Organic solvent:
25.0 parts of DMFDG (dipropylene glycol dimethyl ether) First mixture:
Monomer (a):
2-Hydroxyethyl methacrylate 15.8 parts Monomer (c):
Styrene 6.0 parts Methyl methacrylate 17.0 parts n-Butyl methacrylate 46.2 parts Initiator:
2,2'-Azobis (2-methylbutyronitrile) 2.0 parts Chain transfer agent:
α-Methylstyrene dimer 4.0 parts

After completion of the dropwise addition, the internal temperature was raised to 130 ° C., and then the following second mixture containing the monomer and the initiator was added dropwise over 1.5 hours. The internal temperature was maintained at 130 ° C. during the dropping.

Second mixture:
Monomer (a):
2-Hydroxyethyl methacrylate 6.2 parts monomer (b):
Acrylic acid 2.0 parts Methacrylic acid 0.5 parts Monomer (c):
n-Butyl Methacrylate 6.3 Part Initiator:
Perbutyl O (trade name, manufactured by NOF CORPORATION) 1.5 copies

Then, the internal temperature was cooled to 80 ° C., 3.2 parts of dimethylethanolamine was added dropwise over 0.25 hours, and 94 parts of pure water was subsequently added dropwise over 0.5 hours. The mixture was cooled to room temperature to obtain an aqueous resin composition. The solid content was 45.0%. Using the obtained aqueous resin composition, the viscosity and storage stability were evaluated by the following methods. The results are shown in Table 1.

[Evaluation method]
(1) Initial Viscosity The aqueous resin composition was sealed in a glass bottle, and the viscosity (B-type viscosity, 60 rpm) in an atmosphere of 25 ° C. was measured and evaluated according to the following criteria.
"○": less than 1000 mPa · s "△": 1000 mPa · s or more and less than 5000 mPa · s "×": 5000 mPa · s or more

(2) Storage stability The aqueous resin composition was sealed in a glass bottle, stored in an atmosphere of 40 ° C. for a predetermined period, and then the viscosity was measured by the same method as the initial viscosity. The viscosity change rate and appearance calculated by the post-storage viscosity / pre-storage viscosity × 100 were evaluated according to the following criteria.
"◎": Viscosity change rate after storage for 3 months is 80% to 120%
"○": Does not correspond to "◎", and the rate of change in viscosity after storage for 1 month is 80% to 120%.
"△": Does not correspond to "◎" and "○", and the viscosity change rate after storage for 2 weeks is 80% to 120%.
"X": Does not correspond to any of "◎", "○" and "△", or appearance abnormality such as separation is observed after storage for 2 weeks.

[Examples 2 to 4, Reference Examples 5 to 6, Comparative Examples 1 to 4]
An aqueous resin composition was obtained and evaluated in the same manner as in Example 1 except that the organic solvent and the first monomer mixture were changed as shown in Table 1. The results are shown in Table 1.

The abbreviations in Table 1 indicate the following compounds. The units in Table 1 are all parts by mass except for the evaluation results.
DMFDG: Dipropylene glycol dimethyl ether DMDG: Diethylene glycol dimethyl ether DEDG: Diethylene glycol diethyl ether DMTG: Triethylene glycol dimethyl ether PMA: Propropylene glycol monomethyl ether acetate BDG: Diethylene glycol monobutyl ether Buticero: Ethylene glycol monobutyl ether 2-HEMA: 2-Hydroxyethyl methacrylate St: Stylene MMA: Methyl Methacrylate n-BMA: n-Butyl Methacrylate AA: Acrylic Acid MAA: Methacrylate AMBN: 2,2'-azobis (2-methylbutyronitrile)
αMSD: α-methylstyrene dimer

All of the aqueous resin compositions of Examples 1 to 4 had a low viscosity and good storage stability, and were suitable for an aqueous coating material. On the other hand, in the aqueous resin composition of Comparative Example 1, since the polymer (II) did not contain the structure derived from MSD, the storage stability was insufficient. The aqueous resin composition of Comparative Examples 2 to 4 contains 60 mass of an organic solvent (I) having a solubility parameter (SP value) of 8.50 (cal / cm ³ ) ^1/2 or less according to the Fedors method. Since it does not contain more than%, storage stability was insufficient.

Claims (4)

In an organic solvent (I) containing 60% by mass or more of an organic solvent having a solubility parameter SP value of 8.50 (cal / cm ³ ) ^1/2 or less and a solubility in water of 3 g / 100 g or more by the Polymers method. A method for producing an aqueous resin composition, which comprises a step of polymerizing a radically polymerizable monomer in the presence of an α-methylstyrene dimer to produce a polymer (II), wherein the polymer (II) is produced. In the step of forming the polymer (A), a radically polymerizable monomer (A) containing a hydroxyl group-containing radically polymerizable monomer (a) is polymerized in the presence of the α-methylstyrene dimer in the organic solvent (I). The step (1) for obtaining a dispersion liquid containing P) and the radical polymerizable monomer (B) containing a carboxyl group-containing radical monomer (b) are polymerized in the dispersion liquid containing the polymer (P). A method for producing an aqueous resin composition, which comprises the step (2) of obtaining a dispersion liquid containing the polymer (Q). The amount of the hydroxyl group-containing radical polymerizable monomer (a) and the carboxyl group-containing radical monomer (b) used in the production of the polymer (II) is the monomer that is the raw material of the polymer (II). The method for producing an aqueous resin composition according to claim 1, which is 5 to 50% by mass and 0.5 to 5% by mass, respectively, with respect to the total amount of the above. The method for producing an aqueous resin composition according to claim 1 or 2 , further comprising a step of blending a curing agent into a polymer solution containing an organic solvent (I) and a polymer (II). A method for producing a coating material, in which at least a part of the surface of a base material is coated with the aqueous resin composition produced by the method according to claim 3 .