JP3496737B2 - Method for producing water-dispersed resin composition - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a water-dispersible resin composition which is useful for coating metal materials.

[0002]

2. Description of the Related Art In recent years, labor-saving and energy-saving demands have been strong for coatings and adhesives for coating automobile industrial machinery, steel furniture, electric appliances, etc., and air pollution caused by organic solvents emitted from the coatings. The use of organic solvents is being restricted for the purpose of preventing the above problems and improving the working environment, and the development of solventless paints such as powder paints and radiation-curable paints and water-based paints is being promoted.

[0003] Among them, since the epoxy resin exhibits excellent processability and chemical resistance even in a solvent system, the epoxy resin is often made water-based. For example, a method in which a carboxyl functional polymer is esterified with an epoxy resin in the presence of an amine esterification catalyst and dispersed in water with an amine (JP-A-55-3482), methacrylic acid is reacted with an epoxy group, Further, after polymerizing the acrylic monomer, it is neutralized with an amine and dispersed in water (Japanese Patent Publication No. 59-
37287), a quaternary ammonium hydroxide is produced by reacting an amine-neutralized acrylic resin with a high molecular weight epoxy resin, which reacts with a carboxyl functional polymer to form a carboxyl functional polymer. A method for forming a polymeric quaternary ammonium-amine mixed salt and dispersing it in water (Japanese Patent Publication No. 4-5072), using a catalyst such as benzoyl peroxide, and containing a carboxyl group in the side chain of the epoxy resin. A method of graft-polymerizing an acrylic monomer containing a monomer, neutralizing the resulting resin with ammonia and an amine system, and stably dispersing it in water (Japanese Patent Laid-Open No. 53-1228), acrylic resin, and epoxy resin. A carboxyl group-excessive composite resin composition obtained by mixing a partially bound product and a phenol resin is neutralized with ammonia and water is added. How to make variance (KOKOKU 1-2548
No. 9), an acrylic resin-modified epoxy resin aqueous dispersion obtained by precondensing a phenol resin (Japanese Patent Laid-Open No. 215/1985).
No. 015), a method of using a phenoxy resin instead of an epoxy resin in order to maintain workability (Japanese Patent Publication No.
No. 21279), an aqueous resin composition comprising an epoxy resin having no oxirane ring and an acrylic resin (Japanese Patent Laid-Open No. 6-212046) and the like are disclosed.

However, when an acrylic resin is reacted with an epoxy resin in the presence of an esterification catalyst such as an amine or in the absence of a catalyst, the particles become large, which causes a problem in coating workability. Further, when a carboxyl group-containing monomer is grafted onto the epoxy resin, a low molecular weight ungrafted acrylic resin is produced, the processability is lowered, and cracking easily occurs.
Furthermore, if the epoxy group remains as described above, the storage stability decreases, and if a phenoxy resin is used to improve the processability, the acrylic monomer becomes difficult to graft,
Unreacted phenoxy resin tends to remain.

[0005]

The invention according to claim 1 is capable of being baked for a short time, has a good appearance of the cured coating film, and has excellent boiling water resistance, adhesion and processability. A method of making a composition is provided. In addition to the invention of claim 1, the invention of claim 2 provides a method for producing a water-dispersible resin composition having good dispersibility, stability, corrosion resistance and the like. In addition to the invention of claim 1 or 2, the invention of claim 3 provides a method for producing a water-dispersible resin composition further excellent in adhesiveness, processability and the like.

[0006]

The present invention provides (a) an aromatic compound having an average of 1 or more and less than 2 terminal epoxy groups in one molecule and a number average molecular weight of 3,000 to 7,000. After polymerizing a copolymerizable unsaturated monomer mixture consisting of (b) an ethylenically unsaturated aliphatic carboxylic acid and another copolymerizable unsaturated monomer in the presence of a system epoxy resin, (a) )
With respect to 100 parts by weight of the total amount of the component and the component (b), 0.
80-100 ° C in the presence of 1-2% by weight of volatile base
The present invention relates to a method for producing a water-dispersible resin composition, which comprises heating for 2 hours to 6 hours , then further adding a volatile base to neutralize and disperse in water. Further, the present invention is
Component (a) 60 to 80 parts by weight and component (b) 20 to 4
The present invention relates to a method for producing the water-dispersible resin composition, which is used as 0 parts by weight (the total amount of the components (a) and (b) is 100 parts by weight). In addition, the present invention further provides a method for producing the water-dispersible resin composition, which further comprises (c) a phenol resin in an amount of 1 to 40 parts by weight (based on a total of 100 parts by weight of the components (a) and (b)). Regarding

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing a water-dispersible resin composition of the present invention comprises (a) an average of 1 or more and less than 2 terminal epoxy groups in one molecule and a number average molecular weight of 3,000. ~ 7,0
00 in the presence of an aromatic epoxy resin,
After polymerizing a copolymerizable unsaturated monomer mixture consisting of an ethylenically unsaturated aliphatic carboxylic acid and other copolymerizable unsaturated monomers, heated in the presence of a catalytic amount of a volatile base,
Then, a volatile base is further added to neutralize and then dispersed in water.

The (a) epoxy resin in the present invention is 1
It is necessary to have an average of 1 or more and less than 2 terminal epoxy groups in the molecule. When the average number of the terminal epoxy groups is less than 1 in one molecule, the processability and adhesion of the final resin are deteriorated, while when the number of the terminal epoxy groups is 2 or more, the gelation tends to occur when heated in the presence of an amine esterification catalyst. Become. Further, the (a) epoxy resin in the present invention has a number average molecular weight of 3,000 to
It is necessary to be 7,000, preferably 4,000 to 6,000. If the number average molecular weight is less than 3,000, the processability, adhesion, etc. of the cured coating film on the final resin will decrease, while if it exceeds 7,000, the molecular weight of the epoxy resin will increase, so that the acrylic monomer will increase. Grafting becomes difficult, and unreacted epoxy resin tends to remain.

Examples of the epoxy resin (a) in the present invention include commercially available products such as Epicot 1009, 1010 (manufactured by Shell Chemical Co., Ltd.) and Epomic R309 (manufactured by Mitsui Petrochemical Industry Co., Ltd.). Also, DER343 (diglycidyl ether of bisphenol A, trade name) and bisphenol A, which are sold by Dow Chemical Company, can be used for easy production. In this case, the weight ratio of bisphenol A / DER343 is 22-34.
The ratio of / 78 to 66 is preferable from the viewpoint of controlling the molecular weight.

The reaction method of bisphenol A and DER343 is preferably carried out at a reaction temperature of 180 to 190 ° C. If the reaction temperature is less than 180 ° C, it will take a long time to obtain the final target molecular weight, and the content of low-molecular substances will increase, tending to reduce the curability of the final product. Tends to be difficult. Further, it is preferable not to use a reaction solvent.
When a reaction solvent is used, the reaction time tends to be long and the low molecular weight substance content tends to increase.

Examples of the ethylenically unsaturated aliphatic carboxylic acid in the component (b) in the present invention include α, β-monoethylenically unsaturated carboxylic acids (acrylic acid, methacrylic acid, maleic acid, itaconic acid, etc.). And an α, β-ethylenically unsaturated monomer having a hydroxyl group (acrylic acid 2
-Hydroxyethyl, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, etc.) and the like.

Examples of the other unsaturated monomer in the component (b) in the present invention include alkyl esters of α, β-monoethylenically unsaturated carboxylic acids (methyl acrylate, ethyl acrylate, n-butyl acrylate). , Acrylic acid 2-
Ethylhexyl, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, etc.), α, β-ethylenically unsaturated aliphatic carboxylic acid having a hydroxyl group (2-hydroxyethyl acrylate, acrylic Acid 2-hydroxypropyl,
2-hydroxyethyl methacrylate, 2-methacrylic acid
Hydroxypropyl, etc., acrylamide derivatives (acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, diacetone acrylamide, etc.), glycidyl ester of α, β-monoethylenically unsaturated carboxylic acid (glycidyl acrylate, methacryl) Acid glycidyl), saturated carboxylic acid vinyl ester (vinyl acetate, vinyl propionate, etc.),
Aromatic unsaturated monomer (styrene, α-methylstyrene,
Vinyltoluene, etc.) and the like.

The acid value of the component (b) in the present invention is 23.
It is preferably from 0 to 400, more preferably from 250 to 350. When the acid value is less than 230,
(A) The water dispersibility of the water dispersion resin obtained after the reaction with the epoxy resin tends to be poor, and the stability of the coating tends to be poor. On the other hand, when it exceeds 400, the coating film properties (especially boiling water resistance) tend to be deteriorated, and gelation tends to occur during the reaction with the (a) epoxy resin.

The amount of component (a) used in the present invention is preferably 60 to 80 parts by weight, with the total amount of components (a) and (b) being 100 parts by weight. If the content is less than 60 parts by weight, the workability and corrosion resistance of the coating film will tend to decrease, and if it exceeds 80 parts by weight, the dispersibility and the stability of the coating composition will tend to decrease. The blending amount of the component (b) in the present invention includes the components (a) and (b)
The total amount of the components is 100 parts by weight, preferably 20 to 40 parts by weight. If this blending amount is less than 20 parts by weight, the dispersibility and the stability of the coating tend to decrease, and 4
If it exceeds 0 parts by weight, the workability and corrosion resistance of the coating film tend to be lowered.

The method of polymerizing the component (b) in the presence of the component (a) in the present invention includes, for example, organic dissolution.
Using a radical polymerization initiator (azobisisobutylnitrile, benzoylperoxide, etc.) in the agent, 8
Examples include a method of heating at a temperature of 0 to 150 ° C. for 30 minutes to 8 hours. During this polymerization, the component (b) is grafted onto the component (a). The amount of the radical polymerization initiator used is preferably 4 to 15% by weight or more, and more preferably 6 to 15% by weight, based on the component (b). If the amount used is less than 4% by weight, the polymerizability is low,
Grafting efficiency is poor and water dispersibility, resin stability, etc. tend to be lacking, and if it exceeds 15% by weight, processability, corrosion resistance, etc. tend to deteriorate.

The heating conditions for heating in the presence of a catalytic amount of a volatile base in the present invention are 80 to 100 ° C. and 2
The time is preferably set to 6 hours, more preferably 3 to 4 hours. If the heating time is less than 2 hours, the workability, adhesion, etc. tend to be lowered, and if the heating time is more than 6 hours, the viscosity of the final product tends to be too high. As the volatile base, for example, ammonia, amine or the like is used. Examples of the amine include monopropylamine, monobutylamine, diethylamine, dibutylamine, triethylamine, tributylamine, monoethanolamine, ethylmonoethanolamine, monocyclohexylamine, dimethylaminoethanol, 2
Examples include primary, secondary and tertiary aliphatic or alicyclic amines such as -amino-2-methyl-1-propanol, morpholine and piperidine.

The amount of volatile base used is usually
It is preferably 0.1 to 2% by weight based on 100 parts by weight of the total amount of the components (a) and (b),
It is more preferably 0.2% by weight. If the amount used is less than 0.1% by weight, the workability and corrosion resistance tend to be poor, and if it exceeds 2% by weight, the corrosion resistance, retort resistance, workability and the like tend to decrease.

The above-mentioned volatile base is used in order to neutralize by adding a volatile base in the present invention and disperse in water. The amount of the volatile base used in the neutralization is preferably 0.6 to 1.0 mol per 1 equivalent of the acid group. If the amount used is less than 0.6 mol, the water dispersibility tends to be poor, and if it exceeds 1.0 mol, the viscosity tends to be too high.

In the method for producing the water-dispersible resin composition of the present invention, from the viewpoint of further improving adhesion, processability, etc.,
(C) It is preferable to use a phenol resin.
The (c) phenol resin is not particularly limited, and a resole-type phenol-formaldehyde resin is preferable from the viewpoint of adhesion and the like. As such a resin, for example,
It can be produced by reacting phenols with formaldehyde in a known reaction solvent in the presence of a basic catalyst.

Examples of phenols include bisphenols (bisphenol A, bisphenol F, etc.),
Examples thereof include trifunctional phenols (phenol, 3,5-xylenol, etc.). Also, along with these phenols and trifunctional phenols, P-cresol, P-tert
-Trifunctional phenols such as butylphenol and 2,3-xylenol can also be used in combination. Examples of formaldehydes include formalin, paraformaldehyde, Holmit B, 1B, and M manufactured by Koei Chemical Co., Ltd. Among them, formalin is preferable.

The proportion of phenols and formaldehydes used is preferably 0.5 to 4.0 moles of formaldehyde and more preferably 0.5 to 2.5 moles per mole of phenol. preferable. If the amount of formaldehyde is less than 0.5 mol, unreacted phenol remains and the water solubility tends to be poor, and if it exceeds 4.0 mol, gelation tends to occur.

Examples of the basic catalyst include alkali metal hydroxides, alkaline earth metal hydroxides, amines and the like. Alkali metal hydroxides include sodium hydroxide, lithium hydroxide and potassium hydroxide, and alkaline earth metal hydroxides include magnesium hydroxide and
Examples thereof include barium hydroxide. Examples of amines include ammonia, diethylamine, triethylamine and the like. The amount of basic catalyst used is phenol 1
The amount is preferably 0.01 to 1.0 mol, and more preferably 0.05 to 1.0 mol, based on mol. If the amount used is less than 0.01 mol, the reaction hardly proceeds and it tends to take a long time, and if it exceeds 1.0 mol, the exothermic reaction rapidly progresses and the control of the molecular weight tends to be difficult. .

The reaction conditions are not particularly limited and may be appropriately selected from a wide range, but the reaction temperature is preferably 40 to 120 ° C., and 60 to 120 ° C.
The temperature is preferably 80 ° C. The reaction time is preferably 1 to 8 hours, more preferably 2 to 3 hours.

The resole-type phenol-formaldehyde resin obtained by this synthesis method contains 20 to 40% by weight of a component having a number average molecular weight of 250 or less when it is large and 5 to 20% by weight when it is small. However, it is preferable to reduce the component having a number average molecular weight of 250 or less to 1% by weight or less from the viewpoints of workability and scattering of a low molecular weight substance during baking, which adversely affects the characteristics. Therefore, washing with hot toluene extraction can reduce the components having a number average molecular weight of 250 or less to 1% by weight or less.

This operation will be described in detail as an example.
100 parts by weight of toluene is dissolved and dispersed in 100 parts by weight (solid content) of the phenol resin which is the above reaction product,
Reflux at 110 ° C. and stir for 1 hour. Then, when it is left to stand, it is separated into an upper layer toluene and a lower layer phenol resin into two layers. Therefore, by removing only the upper toluene layer by decantation and repeating the above washing 5 to 10 times, the phenol resin component having a number average molecular weight of 250 or less can be reduced to 1% by weight or less.

The number of methylol groups of the resol-type phenol-formaldehyde resin is preferably 0.5 to 2.0 per unit of bisphenol unit because of the characteristics of the coating material.

The amount of the component (c) used in the present invention is preferably 1 to 40 parts by weight, preferably 3 to 20 parts by weight, based on 100 parts by weight of the total amount of the components (a) and (b).
It is more preferable to set it as a weight part. If the amount is less than 1 part by weight, the adhesion to metal tends to be poor,
If it exceeds the weight part, the workability tends to be poor.

In the water-dispersible resin composition obtained by the present invention, a catalyst such as an inorganic acid (hydrochloric acid, phosphoric acid, etc.), an organic acid (paratoluene sulfonic acid, etc.), a component (a) and a component (b).
It is also possible to add 1 part by weight or less to 100 parts by weight of the total amount of the components. If the amount used exceeds 1 part by weight, the workability tends to decrease.

The water-dispersible resin composition obtained according to the present invention comprises alkyl alcohols (methanol, ethanol,
n-propanol, isopropanol, n-butanol
, Sec-butanol, tert-butanol, isobutanol, etc.), ether alcohols (methyl cellosolve,
Ethyl cellosolve, propyl cellosolve, butyl cellosolve, 2-ethylhexyl cellosolve, hexyl cellosolve, methyl carbitol, ethyl carbitol, butyl carbitol, etc.), ether esters (methyl cellosolve acetate, ethyl cellosolve acetate, etc.),
It can be used by diluting a mixed solvent of water-soluble organic solvent such as other dioxane, diacetone alcohol, 3-methoxy-3-methylbutan-1-ol and the like as a diluent to obtain an appropriate solid content. . As the blending amount of water and the organic solvent, water / organic solvent is 100/0 to 80/2.
It is preferably 0 (weight ratio).

The water-dispersible resin composition obtained according to the present invention may contain pigments and other additives depending on the purpose. Examples of the method for coating the water-dispersible resin composition obtained by the present invention include spray coating, coating with a roll coater, dipping and the like.

[0031]

EXAMPLES The present invention will be described below with reference to examples. Production Example 1 (Production of Aromatic Epoxy Resin (A)) Diglycidyl ether type DE of bisphenol A
405 parts by weight of R343 (manufactured by Dow Chemical Co.) and 208 parts by weight of bisphenol A were weighed and put into a flask equipped with a stirrer, a reflux condenser, a thermometer, and an inert inlet. The mixture was heated for 30 minutes to reach 130 ° C., then the heating was stopped, the reaction heat was used to raise the temperature to 190 ° C., and the mixture was reacted at that temperature for 2 hours to give the aromatic epoxy resin (A). Synthesized. Then butanol 224.8
It was diluted with parts by weight and 87.6 parts by weight of Solfit. 1
The average number of epoxy groups in the molecule was 1.35, and the number average molecular weight (Mn) was 4,000.

Production Example 2 (Production of Aromatic Epoxy Resin (B))

[Table 1] A flask equipped with a stirrer, a reflux condenser, a thermometer, and an inert inlet was charged with the materials shown in Table 1 and gradually heated to 11
The temperature was raised to 8 ° C. and completely dissolved to obtain an aromatic epoxy resin (B). (Heating residue 50% by weight)

Production Example 3 (Preparation of Monomer Mixture Solution (C))

[Table 2] The materials in Table 2 were blended to obtain a monomer mixture solution (C).

Production Example 4 (Production of Phenol Resin (I)) 228.3 parts by weight of bisphenol A, 22.5 parts by weight of paraformaldehyde, 170 parts by weight of toluene were added to a stirrer, a reflux condenser, a thermometer, an inert inlet. Was charged into a flask equipped with a reactor, 1.5 parts by weight of oxalic acid was added as a catalyst, and the mixture was reacted at 90 to 95 ° C. for 3 hours, and then 200 under reduced pressure.
The temperature was raised to 160 ° C. in mmHg to perform desolvation. To 100 parts by weight (solid content) of the above reaction product, 100 parts by weight of toluene was charged and heated to perform hot toluene extraction. Toluene reflux is performed at 110 ° C for 1 hour to form a toluene layer on the upper layer,
The lower layer was separated into two resin layers, and only the upper toluene layer was removed. As a result of performing the above extraction 10 times, the amount of the component having a number average molecular weight of 250 or less was 0.8% by weight.

258 parts by weight of this reaction product (base resin), 37.5 parts by weight of paraformaldehyde and 10.1 parts by weight of triethylamine were charged, and further 129 parts by weight of xylene and 129 parts by weight of butanol were charged into a flask as a reaction solvent. The reaction was carried out at 80 ° C. for 6 hours to obtain a phenol resin (I). The obtained phenol resin (I) has a heating residue of 50% by weight, a degree of methylolation per bisphenol of 0.7, and a number average molecular weight (M
n) is 1,282 and weight average molecular weight (Mw) is 6,58.
9, the dispersity was 5.14. The component having a number average molecular weight of 250 or less was 0.7% by weight.

Production Example 5 (Production of Phenolic Resin (II)) The same base resin as in Production Example 4 (258 parts by weight), paraformaldehyde (56.3 parts by weight), triethylamine (10.
1 part by weight was charged, and xylene 1 was further used as a reaction solvent.
29 parts by weight and 129 parts by weight of butanol were charged into a flask and reacted at 90 ° C. for 2 hours to give a phenol resin (I
I) got. The obtained phenol resin (II) had a heating residue of 50% by weight, a degree of methylolation per bisphenol of 0.95, and a number average molecular weight (Mn) of 1,48.
0, the weight average molecular weight (Mw) was 7,800, and the dispersity was 5.27. Further, the component having a number average molecular weight of 250 or less was 0.5% by weight.

Example 1

[Table 3] A flask equipped with a stirrer, a reflux condenser, a thermometer, and an inert inlet was charged with the ingredients shown in Table 3 and heated to 95 ° C.,
Add the product in Table 3 over 2 hours at the same temperature for 3
The mixture was stirred for a polymerization reaction to obtain an epoxy acrylic graft copolymer. Then, the substances shown in Table 3 were added and the reaction was carried out for 3 hours. Before and after the reaction, disappearance of the epoxy group was confirmed by ¹ H-NMR. Next, after adding in Table 3, neutralizing the obtained epoxy acrylic graft copolymer,
Was dropped over 1 hour to obtain a water-dispersed resin composition (solid content: 28.5% by weight). Further, the solvent was removed in order to remove butanol, and a white water-dispersed resin composition having a heating residue of 35.1% by weight was obtained. The final solvent composition, viscosity (measured by a rotary viscometer), acid value, pH and dispersion state (confirmed by sight) of the obtained water-dispersible resin composition are shown in Table 5 as characteristics.

Examples 2 to 9 In the same manner as in Example 1, resins were prepared with the formulations shown in Table 4 to obtain water-dispersible resin compositions. The phenol resin was uniformly mixed before dropping the ion-exchanged water. The resulting water-dispersed resin composition, heating residue, final solvent composition, viscosity,
The acid value, pH and dispersion state are shown in Table 5 as properties.

[0039]

[Table 4]

[0040]

[Table 5]

Comparative Examples 1-5 With the formulation shown in Table 6, dimethylaminoethanol was added,
A water-dispersed resin composition was obtained in the same manner as in Example 1 except that the reaction was not performed for 3 hours. The heating residue, final solvent composition, viscosity, acid value, pH and dispersion state of the obtained water-dispersible resin composition are shown in Table 7 as properties.

[0042]

[Table 6]

[0043]

[Table 7]

(Preparation of Coating Film) The water-dispersible resin compositions obtained in Examples 1 to 9 and Comparative Examples 1 to 4 were adjusted to 30% by weight in solid content, and coating films were prepared under the following conditions. did. In Comparative Example 5, no coating film was prepared because it gelled. Substrate: Tin plate Coating method: Using a bar coater # 18, coating was performed so that the film thickness after baking was 5 to 7 μm. Baking conditions: After baking at 270 ° C. for 30 seconds,
It was left at room temperature for 24 hours. The appearance of each of the obtained coating film was confirmed by eye <br/> view, the pencil hardness test, bending test and耐沸aqueous test test (appearance and adhesion) coating characteristics by the following method The results are shown in Tables 8 and 9 .

(Film coating property test method) -Pencil hardness: Evaluated according to JIS K5400 using Mitsubishi Uni. Bending: The test plate was folded in two at 3φ and the degree of cracking of the coating film at the bent portion was determined. ◯: No cracks Δ: Some cracks were found ×: Significant cracks were observed-Boiling water resistance (appearance): After immersion in boiling water for 1 hour, the pieces were taken out, and the appearance was visually judged. ◯: No whitening △: Slight whitening X: Significant whitening-Boiling resistance (adhesion): After soaking in boiling water for 1 hour, cut 100 1mm x 1mm squares into a scotch tape It was peeled off and judged by the ratio of the coating film remaining on the substrate.

[0046]

[Table 8]

[0047]

[Table 9]

[0048]

The method for producing a water-dispersible resin composition according to claim 1 is excellent in stability, can be baked at high temperature for a short time, and has a good appearance when formed into a cured coating film, and has boiling water resistance and adhesion. A water-dispersible resin composition having excellent properties and processability can be obtained.
The method for producing a water-dispersible resin composition according to claim 2 has the effects of the method for producing a water-dispersible resin composition according to claim 1, and further has good dispersibility, stability, corrosion resistance, and the like. A resin composition can be obtained. The method for producing a water-dispersible resin composition according to claim 3 has the effects of the method for producing a water-dispersible resin composition according to claim 1 or 2, and is more excellent in adhesiveness and processability. A composition can be obtained.

Claims (3)

(57) [Claims] 1. (a) An average of 1 or more and less than 2 terminal epoxy groups in one molecule and a number average molecular weight of 3,000 to.
In the presence of an aromatic epoxy resin of 7,000 ,
( B) After polymerizing a copolymerizable unsaturated monomer mixture consisting of an ethylenically unsaturated aliphatic carboxylic acid and other copolymerizable unsaturated monomers , the total amount of the components (a) and (b)
Heating in the presence of 0.1 to 2% by weight of a volatile base to 100 parts by weight at 80 to 100 ° C. for 2 to 6 hours ,
Next, a method for producing a water-dispersible resin composition, which comprises further adding a volatile base to neutralize and disperse in water. 2. Component (a) 60 to 80 parts by weight and component (b) 20 to 40 parts by weight (component (a) and component (b)).
The method for producing a water-dispersible resin composition according to claim 1, wherein the total amount of the components is 100 parts by weight). 3. (c) Phenolic resin 1 to 4
The method for producing a water-dispersible resin composition according to claim 1 or 2, wherein 0 part by weight (based on 100 parts by weight of the total of the components (a) and (b)) is added.