JPH07228829A - Water-based coating composition - Google Patents

Abstract

PURPOSE:To relatively easily obtain the subject composition free from any toxicity problem, excellent in storage stability, presenting adequate physical properties in terms of resistances to water and solvents even in the case of being used in an air-drying status, and in good balance between the hardness and elasticity of the coating film therefrom. CONSTITUTION:This water-based coating composition comprises (A) a water- based polyurethane resin obtained by reaction of a hydrazide group-contg. compound with an NCO group-bearing urethane prepolymer derived from (a) a polyisocyanate compound and (b) an active hydrogen compound having nonionic and/or ionic hydrophilic group(s) (or group(s) convertible into hydrophilic group(s) afterward) and (B) a polycarbonyl compound having two or more carbonyl groups at a weight ratio A/B (on a solid basis) of (100:0.1) to (0.5:100).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to waterborne coating compositions. More specifically, it relates to a coating composition containing a crosslinkable water-based polyurethane resin, and is useful as a coating agent for substrates such as metals, plastics, paper, wood, cement and leather.

[0002]

2. Description of the Related Art Aqueous polyurethane resins are widely used for paints, adhesives, and coating agents because they are excellent in film forming property and give a film having abrasion resistance, adhesiveness, rubber elasticity and the like. However, when it is used in an ordinary dry state, it does not exhibit sufficient physical properties in terms of water resistance, solvent resistance, etc., and therefore the range of use is limited to indoors. Further, in the present situation, further improvement is desired in terms of the balance between hardness and elasticity.

For these problems, it is useful to introduce a crosslinking system having both low temperature curability and storage stability into the water-based polyurethane resin. For example, it has been proposed in U.S. Pat. No. 4,598,121 to provide a low temperature self-crosslinking polyurethane emulsion by incorporating hydrazide groups into the polyurethane chain and adding formaldehyde. However, the use of formaldehyde is toxic and environmentally undesirable, so
There is no choice but to limit it to a specific use.

In US Pat. No. 4,983,662,
It has been proposed to provide a self-crosslinkable polyurethane aqueous dispersion using a vinyl polymer having a carbonyl functional group or a non-vinyl-based polycarbonyl compound instead of formaldehyde. However, according to this method, in order to introduce the hydrazide group in a suspended form in the polyurethane chain, it is necessary to use a complicated process and a special raw material, and it is possible to effectively introduce the hydrazide group to the particle surface of the polyurethane emulsion. It is difficult and adversely affects the weather resistance and water resistance of the film formed by the remaining hydrazide group-introducing raw material.

Further, in Japanese Patent Laid-Open No. 1-301761, the urethane prepolymer having an NCO group is chain-extended with hydrazine or water-soluble dihydrazines (ethylene-1,4-dihydrazine etc.) to give a hydrazine group to polyurethane. It has been proposed to introduce and crosslink with vinyl polymers having carbonyl functionality. However, the hydrazine and water-soluble dihydrazines used in this method are toxic and it is difficult to control the reaction with the NCO group. Therefore, the resulting aqueous polyurethane resin is toxic due to the remaining hydrazine derivative, and the hydrazine group is not effectively introduced into the polyurethane.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a polyurethane-based aqueous coating composition which solves the above-mentioned problems of the prior art,
That is, in addition to being easy to produce, the resulting polyurethane-based aqueous coating composition has no problem of toxicity and has good storage stability, and is sufficient in terms of water resistance, solvent resistance, etc. even when it is used in an ordinary dry condition. It is an object of the present invention to provide a polyurethane-based aqueous coating composition that exhibits excellent physical properties and can form a film having a well-balanced hardness and elasticity.

[0007]

The present inventors have found that the above problems can be solved by using an aqueous coating composition comprising a specific hydrazide group-containing aqueous polyurethane resin and a polycarbonyl compound, and the present invention has been made. Has been completed. That is, the present invention provides an NCO group derived from a polyisocyanate compound (a) and an active hydrogen compound (b) having a nonionic and / or ionic hydrophilic group (or a group which can be subsequently converted into a hydrophilic group). The urethane prepolymer has an aqueous polyurethane resin (A) obtained by reacting the compound with a hydrazide group, and a polycarbonyl compound (B), and the solid content weight ratio is (A) /
(B) = 100 / 0.1 to 0.5 / 100, which is an aqueous coating composition.

The present invention will be described in detail below. In the present invention, as the polyisocyanate compound (a) used for synthesizing the urethane prepolymer having an NCO group, for example, 2,4-tolylene diisocyanate, 2,
6-tolylene diisocyanate and mixtures thereof (TD
I), diphenylmethane-4,4'-diisocyanate (MDI), naphthalene-1,5-diisocyanate (NDI), 3,3-dimethyl-4,4-biphenylene diisocyanate (TODI), crude TDI, polymethylene polyphenyl diisocyanate, crude MDI Aromatic diisocyanates such as xylylene diisocyanate (XDI), aromatic alicyclic diisocyanates such as phenylene diisocyanate, 4,4′-methylenebiscyclohexyl diisocyanate (hydrogenated MDI), isophorone diisocyanate (IPDI), dimethylcyclohexane diisocyanate (water Alicyclic diisocyanates such as XDI), diisocyanates such as aliphatic diisocyanates such as hexamethylene diisocyanate (HDI), and 1,8-diisocyanate. Isocyanato-4-isocyanatomethyl octane, diisocyanate compound biuret bond, urea bond, isocyanurate bond, urethane bond,
Examples thereof include polyfunctional isocyanates oligomerized by allophanate bonds and uretdione bonds, and combinations thereof.

Further, in the present invention, an active hydrogen compound having a nonionic and / or ionic hydrophilic group (or a group which can be converted into a hydrophilic group later) used for synthesizing a urethane prepolymer having an NCO group. Examples of the ionic hydrophilic group in (b) include anionic groups such as tertiary amine salts of carboxylic acids and cationic groups such as quaternary ammonium salts.

Examples of the active hydrogen compound having an anion group (or a group which can be converted into an anion group later) include α,
α'-Dimethylolpropionic acid, α, α'-dimethylolacetic acid, α, α'-dimethylolbutyric acid, α, α'-dimethylolvaleric acid and other α, α'-dimethylolalkanoic acids, taurine and other aminosulfonic acids Etc., and combinations thereof. Of these, α, α'-dimethylolpropionic acid is preferred. The acid group of these active hydrogen compounds can be converted into an anionic group by neutralizing with a base during the synthesis of the urethane prepolymer or during emulsification (or water solubilization). As the base used for neutralization,
For example, amine compounds such as triethylamine, ammonia, diethanolamine, dimethylaminoethanol, methyldiethanolamine, and dibutylamine, KO
Examples thereof include alkali metal hydroxides such as H, NaOH, and LiOH, and combinations thereof.

Examples of the active hydrogen compound having a cation group (or a group which can be converted into a cation group later) include N-alkyldialkanolamines such as N-methyldiethanolamine and N-butyldiethanolamine, triethanolamine and tripropanolamine. Trialkanolamines such as N, N-dimethylethanolamine,
N, N-dialkylmonoalkanolamines such as N, N-diethylethanolamine, addition products of alkylene oxides (ethylene oxide, propylene oxide, etc.) having 2 to 4 carbon atoms, and combinations thereof. . The tertiary amino group of these active hydrogen compounds can be converted into a cationic group by neutralizing with an acid or quaternizing with an alkylating agent during the synthesis of a urethane prepolymer or during emulsification (or water solubilization). Examples of the acid used for neutralization include acetic acid, lactic acid, hydrochloric acid, phosphoric acid, sulfuric acid and the like, and combinations thereof. As the alkylating agent,
Examples thereof include dimethyl sulfate, diethyl sulfate, methyl chloride, methyl iodide, benzyl chloride and the like.

As the nonionic hydrophilic group, there may be mentioned, for example, a suspended polyoxyalkylene group, especially a polyoxyethylene group. Examples of the active hydrogen compound having these groups include diols having a suspended polyoxyethylene chain as described in US Pat. No. 3,905,929. Further, as a raw material for synthesizing the urethane prepolymer, other active hydrogen compound (c) can be used if necessary. As the other active hydrogen compound (c), polyols having a number average molecular weight of 400 to 8000 are preferable, and a molecular weight of 400 selected from polyhydric alcohols and / or polyvalent amines as necessary.
The following low molecular weight active hydrogen compounds can be used in combination.

The above-mentioned polyols having a number average molecular weight of 400 to 8000 include polycarbonate polyols, polyether polyols, polyester polyols and polybutadiene glycols, which can be used alone or in combination of two or more kinds. Among these, it is preferable to use a polycarbonate polyol from the viewpoint of water resistance, weather resistance and the like.

Polycarbonate polyols include products obtained by reacting dihydric alcohols with a carbonate agent selected from phosgene, dialkyl carbonates, diallyl carbonates and alkylene carbonates in the presence or absence of a catalyst. Can be mentioned. Examples of the dihydric alcohols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,
4-butanediol, neopentyl glycol, 1,5
-Pentanediol, 1,3-pentanediol, 1,
6-hexanediol and the like, or a combination of two or more of these may be used. The obtained polycarbonate polyol can be used alone or in combination of two or more kinds. Among these polycarbonate polyols, JP-A-2-289616 and JP-A-5-2526 are preferred in terms of flexibility and the like.
Amorphous polycarbonate polyols such as those described in JP-A No. 4 are preferable, and polytetramethylene carbonate diol produced in the presence of an acidic substance is preferable from the viewpoint of solvent resistance, heat-resistant yellowing and the like. (For example, the method described in Japanese Patent Application No. 4-258748) Specific examples of the polyether polyol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyoxyethylene-oxypropylene (random and / or block) glycol. , Polyoxyethylene-oxytetramethylene (random and / or block) glycol, polyoxypropylene-oxytetramethylene (random and / or
Or block) glycol, polyhexamethylene glycol and the like, and a combination of two or more of these.

Specific examples of the polyester polyol include polyethylene adipate, polybutylene adipate, polyethylene butylene adipate, polybutylene hexamethylene adipate, polydiethylene adipate,
Examples thereof include poly (polytetramethylene ether) adipate, polyethylene azelate, polyethylene sebacate, polybutylene azelate, polybutylene sebacate, and polycaprolactone diol, and combinations of two or more thereof.

The polybutadiene glycols include polybutadiene homopolymer type having hydroxyl groups at both ends, polybutadiene copolymer type (styrene butadiene copolymer, acrylonitrile butadiene copolymer, etc.), and hydrogenation of some or all of these unsaturated double bonds. And the like, and combinations of two or more of these.

Specific examples of the low molecular weight active hydrogen compound having a molecular weight of usually 400 or less include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,
4-butanediol, neopentyl glycol, 1,5
-Pentanediol, 1,3-pentanediol, 1,
Dihydric alcohols such as 6-hexanediol, hydrogenated bisphenol A and cyclohexanedimethanol; trihydric or higher alcohols such as glycerin, trimethylolpropane and pentaerythritol; amino alcohols such as monoethanolamine and diethanolamine; ethylenediamine, Hexamethylenediamine, aliphatic amines such as diethylenetriamine; isophoronediamine, 4,4-
Examples thereof include alicyclic amines such as methylenebis (cyclohexylamine), and combinations of two or more of these.

The urethane prepolymer comprises (a) and (b) and, if necessary, (c) from about 30 ° C to about 130 ° C.
It is obtained by carrying out a urethanization reaction at a temperature of ° C under substantially anhydrous conditions. NC of polyisocyanate compound (a) used in producing the urethane prepolymer
In an active hydrogen compound (b) (and optionally other active hydrogen compound (c)) having an O group and a nonionic and / or ionic hydrophilic group (or a group which can be subsequently converted into a hydrophilic group) The equivalent ratio of the active hydrogen group capable of reacting with the NCO group (excluding an ionic hydrophilic group (or a group which can be converted into a hydrophilic group later) such as COOH) is usually 1.1 to
It is 5.0: 1.0, preferably 1.1 to 2.0: 1.0.

In producing the urethane prepolymer,
A catalyst can be used if desired. Specific examples of the catalyst include salts of metals and organic and inorganic acids such as dibutyltin dilaurate, stannous octoate and lead octylate, organic metal derivatives, organic tertiary amines such as triethylamine and triethylenediamine, and diamines. Examples thereof include zabicycloundecene catalyst.

Further, the urethane prepolymer can be produced without solvent or in a solvent. As the solvent, those which are inactive to the NCO group or which are less active than the reaction components can be used. Specifically, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and other ketone solvents; dioxane, tetrahydrofuran, diethylene glycol dimethyl ether, and other ether solvents; dimethylformamide, dimethylacetamide, and other amide solvents; N-methyl-2-pyrrolidone, etc. Lactam solvent, sulfoxide solvent such as dimethyl sulfoxide, ester solvent such as ethyl acetate and cellosolve acetate,
Alcohols such as t-butanol and diacetone alcohol, aromatic hydrocarbon solvents such as toluene xylene, n-
Examples thereof include aliphatic hydrocarbon solvents such as hexane and the like, and their combined use. Of these, acetone, methyl ethyl ketone, and N-methyl-2-pyrrolidone are particularly preferable from the viewpoint of emulsification and dispersibility in water. The solvent may remain in the water-based polyurethane resin (polyurethane emulsion or polyurethane aqueous solution), but it can also be distilled off by heating under normal pressure or reduced pressure after forming an emulsion (or aqueous solution).

The aqueous polyurethane resin (A) in the present invention is obtained by reacting the NCO group-containing urethane prepolymer obtained by the above-mentioned method with a hydrazide group-containing compound. At this time, the equivalent ratio of the NCO group of the urethane prepolymer to the active hydrogen group of the hydrazide group-containing compound is 1.0: 0.3 to 10.0, preferably 1.0: 1.0 to 2.0. is there.

Specific examples of the hydrazide group-containing compound include oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, itaconic acid, itaconic acid, itaconic acid, itaconic acid, Dicarboxylic acid dihydrazides such as acid dihydrazide and phthalic acid dihydrazide, tricarboxylic acid trihydrazides such as nitrilotriacetic acid trihydrazide and trimellitic acid trihydrazide, carbonic acid dihydrazides represented by the general formula (1), and general formula (2) Bissemicarbazides, water-soluble acid hydrazide polymers represented by the general formula (3), and the like (for example, JP-A-55-6535).
Japanese Patent Publication)), and combinations thereof.

[0023]

[Chemical 1]

[0024]

[Chemical 2]

[0025]

[Chemical 3]

As the hydrazide group-containing compound, it is preferable to use a compound having an appropriate hydrophilicity.
Examples thereof include adipic acid dihydrazide, succinic acid dihydrazide, sebacic acid dihydrazide, and carbodihydrazide. Further, the use of a polyfunctional hydrazide compound containing three or more hydrazide groups in one molecule such as the above-mentioned tricarboxylic acid trihydrazides and water-soluble acid hydrazide-based polymers makes the introduction amount of the hydrazide group into the water-based polyurethane resin It is preferable because it increases. The hydrazide group-containing compound may be prepared by reacting at least a part of the hydrazide group with a monoaldehyde, a monoketone or the like (preferably having a boiling point of 30 to 200 ° C., such as acetone or methyl ethyl ketone) in advance to block it as a hydrazone group. It can also be used.

In the present invention, as a specific example of the method of reacting the urethane prepolymer with the hydrazide group-containing compound to obtain an aqueous polyurethane resin, the urethane prepolymer is mixed with the hydrazide group-containing compound under appropriate stirring. A method of reacting by adding an aqueous solution. Under moderate agitation,
A method in which water is added to the urethane prepolymer to form a dispersion (or an aqueous solution), and then an aqueous solution of the hydrazide group-containing compound is added and reacted. A method in which the urethane prepolymer is added and reacted in an aqueous solution of the hydrazine derivative under appropriate stirring. Examples include a method of reacting a urethane prepolymer with a hydrazide group-containing compound in the absence of solvent or an organic solvent, and then adding water to form a dispersion (or an aqueous solution). In any of the above-mentioned methods, a surfactant may be added at any stage for the purpose of assisting the dispersibility and dispersion stability of the water-based polyurethane resin, if necessary. When a cationic or anionic hydrophilic group is introduced into the urethane prepolymer, this surfactant may be the same ionic group or nonionic.

When reacting the urethane prepolymer with the hydrazide group-containing compound, a chain extender may be used in combination with the hydrazide group-containing compound, if necessary. Examples of the chain extender include ethylenediamine, propylenediamine, hexamethylenediamine, tolylenediamine, xylylenediamine, diphenyldiamine,
Various diamines such as diaminodiphenylmethane, diaminocyclohexylmethane, piperazine, 2-methylpiperazine and isophoronediamine; polyethylene polyamines such as diethylenetriamine and the like and combinations thereof can be mentioned. Aqueous polyurethane resin (A) thus obtained
The resin content of can be manufactured at a concentration of 0.1 to 95 wt%,
From the viewpoint of manufacturing, 10 to 50 wt% is preferable.

If necessary in the production of the water-based polyurethane resin (A), various additives may be added for the purpose of improving weather resistance and the like. When using additives,
Usually, it is good to add it during the synthesis of urethane prepolymer, but if the additive is water-soluble or reacts with the reaction component such as isocyanate component, dispersion (or aqueous solution)
And then add it. Specific examples of the additive include
For example, hindered phenol-based, phosphite-based, thioether-based antioxidants, benzophenone-based, benzotriazole-based, salicylate-based UV absorbers, hindered amine-based light stabilizers, organic halogen-based flame retardants, etc. And an antistatic agent, a water repellent agent, and the like, as well as combinations thereof.

In the present invention, the aqueous polyurethane resin (A) thus obtained and the polycarbonyl compound (B) are obtained.
By mixing the two, the functional connection is strongly developed. It is considered that this binding is caused by an organic reaction between the hydrazine functional group and / or the hydrazone functional group in the water-based polyurethane resin (A) and the carbonyl group in the polycarbonyl compound (B) when forming a film. To be

The polycarbonyl compound (B) is a compound having two or more carbonyl groups, such as polyketones such as glyoxal, 2,5-hexanedione and acetylacetone, glutardialdehyde, succinic dialdehyde and the like. Polyaldehydes, JP-A-2-238
A carbonyl group-containing polyurethane prepared from a mono- and / or polyalcohol having a carbonyl group such as hydroxyacetone as described in JP-A No. 015,
JP-A-63-51180 and JP-A-62-7274
No. 2, Japanese Patent Publication No. 1-15011, Japanese Patent Publication No. 1-4
No. 5,497, and JP-A-4-214747, carbonyl group-containing ethylenically unsaturated monomers such as diacetone acrylamide, diacetone methacrylamide, acrolein, vinyl methyl ketone, and acetoacetoxyethyl methacrylate. Examples thereof include aqueous copolymer emulsions having a body as a copolymerization component, and combinations thereof. Among these polycarbonyl compounds (B), a carbonyl group-containing ethylenically unsaturated monomer is used as a copolymerization component from the viewpoint of the balance of hardness and elasticity of the film formed by the aqueous polyurethane resin (A) of the present invention. Aqueous copolymer emulsions are preferred. Further, from the viewpoint of weather resistance, the carbonyl group-containing ethylenically unsaturated monomer is replaced with another ethylenically unsaturated monomer in the presence of the hydrolyzable silane described in JP-A-4-214747. Aqueous copolymer emulsions obtained by copolymerizing with a monomer are preferable.

In the present invention, the mixing ratio of the water-based polyurethane resin (A) and the polycarbonyl compound (B) is
The solid content weight ratio is (A) / (B) = 100 / 0.1
It should be within the range of 0.5 / 100. If the film thickness deviates from this range, the resulting film will not show sufficient physical properties in terms of water resistance, alkali resistance, etc., and will also have an insufficient balance of hardness and elasticity.

The water-based coating composition of the present invention may optionally contain a pigment, a filler, a dispersant, a wetting agent, a thickener, a rheology control agent, a defoaming agent, a plasticizer, a film-forming auxiliary agent, a rust preventive agent and the like. Depending on each purpose, selected, combined and blended,
It can be used for various purposes such as a clear coat agent, a top coat agent, a paint, an undercoat agent, an impregnating agent for cloth or paper, and various adhesives.

[0034]

EXAMPLES Parts in the examples mean parts by weight. The measuring method of each measured value used in the examples is as follows. Sample film used to measure physical properties (thickness is about 100μ
m, width 10 mm, length 60 mm) was prepared by film-forming the aqueous coating composition on a glass plate at room temperature for 5 days. Tensile strength is measured by Tensilon tensile tester (Orientec R Co., Ltd.)
TA-100), atmosphere 25 ° C x 65% RH, measurement length 3
It was measured at 0 mm and a pulling speed of 300 mm / min. The water resistance was evaluated by the presence or absence of whitening in the film state after the sample film was immersed in ion-exchanged water at room temperature for 1 week. The solvent resistance was evaluated in the film state after the sample film was immersed in acetone at room temperature for 24 hours.

Production Example of Waterborne Polyurethane Resin (A) 1116 parts of polytetramethylene carbonate diol (C4PCDL) having a hydroxyl value of 54.6, 363 parts of isophorone diisocyanate (IPDI), 55 parts of triethylamine (TEA), dimethylolpropionic acid ( DMP
A) 73 parts, methyl ethyl ketone (MEK) 1607
And 0.04 part of dibutyltin dilaurate (BTL) were placed in a reactor having a reflux condenser, a thermometer and a stirrer, and a urethanization reaction was performed at 80 ° C. for 6 hours to obtain an NCO-terminated prepolymer solution. . To the prepolymer solution adjusted to 30 ° C., 4089 parts of a 3.5% aqueous solution of adipic dihydrazide was added with stirring over about 30 minutes. Subsequently, this was heated under reduced pressure to 80 ° C. over 3 hours, and kept for 2 hours to remove MEK, and then ion-exchanged water was added to adjust the concentration.
%, Viscosity (B type viscometer, 60 rpm, 20 ° C.) 16 cp
A polyurethane emulsion (A-1) having a particle size of s, a particle size of 1040 and a pH of 7.8 was obtained.

In the same manner as above, the raw materials shown in Table 1 were used to prepare water-based polyurethane resins (A-2) and (A-3) having the properties shown in Table 1. Production Example of Polycarbonyl Compound (B) In a reactor having a reflux condenser, a dropping tank, a thermometer and a stirrer, 300 parts of deionized water, Perex OTP (manufactured by Kao Corporation, sodium dioctylsulfosuccinate 4)
2 parts of 0% aqueous solution, Emulgen 950 (manufactured by Kao Corporation,
1 part of 25% aqueous solution of polyoxyethylene nonyl phenyl ether and 1 part of dodecylbenzene sulfonic acid were added and the temperature in the reaction vessel was raised to 80 ° C., then 11 parts of methacrylic acid, 194 parts of styrene, acrylic acid. A mixed solution of 275 parts of butyl, 20 parts of diacetone acrylamide, 330 parts of ion-exchanged water, 5 parts of Emulgen 950 and 1 part of ammonium persulfate was allowed to flow into the reaction vessel from the dropping tank over 3 hours. The temperature in the reaction vessel is 80 ° C during the inflow.
Kept at. After the end of the inflow, the temperature in the reaction vessel was raised to 85 ° C. and maintained for 6 hours. After cooling to room temperature, 25% aqueous ammonia solution was added to adjust the pH to 8, and the mixture was filtered through a 100-mesh wire net to obtain a solid content of 42.8% and a particle size of 105.
0 carbonyl group-containing copolymer aqueous emulsion (B
-1) was obtained.

[0037]

Examples 1 to 3 and Comparative Examples 1 to 4 The water-based polyurethane resin (A) and the polycarbonyl compound (B) were blended as shown in Table 2 to obtain water-based coating compositions. All of these compositions had good storage stability with little change in viscosity even when stored at 40 ° C. for 1 month. Table 2 shows the results of the physical property test of the film.

[0038]

[Table 1]

[0039]

[Table 2]

[0040]

As is clear from the above results, the water-based coating composition according to the present invention is relatively easy to produce and has excellent storage stability, as well as water resistance even when used in a normal dry condition. It is possible to obtain a film which has sufficient physical properties in terms of solvent resistance and has a well-balanced hardness and elasticity. Therefore, the present invention provides an excellent water-based coating composition that can be used for various purposes such as a clear coating agent, a top coating agent, a paint, an undercoating agent, a cloth or paper impregnating agent, and various adhesives. .

Claims (1)

[Claims] 1. An active hydrogen compound (b) having a polyisocyanate compound (a) and a nonionic and / or ionic hydrophilic group (or a group which can be subsequently converted into a hydrophilic group).
A water-based polyurethane resin (A) obtained by reacting a urethane prepolymer having an NCO group derived from the compound with a hydrazide group-containing compound, and a polycarbonyl compound (B)
And the solid content weight ratio is (A) / (B) = 100.
/0.1-0.5/100 The water-based coating composition characterized by the above-mentioned.