JPH07228830A - Water-based coating composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition excellent in storage stability, presenting adequate physical properties in terms of resistance to water and solvents even in the case of being used in an air-drying status, and capable of giving coating films good in balance between hardness and elasticity. CONSTITUTION:This composition comprises (A) a polyurethane emulsion obtained by mixing 100 pts.wt. of an NCO group-bearing urethane prepolymer derived from (a) a diisocyanate compound and (b) an active hydrogen-bearing compound including a polyol 400-8000 in number-average molecular weight with (c) 0.5-500 pts.wt. of a polyisocyanate compound followed by reaction with a hydrazine derivative in the presence of water and (B) a polycarbonyl compound at a weight ratio A/B (on a solid basis) of (100:0.1) to (5:100).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to aqueous coating compositions. Further, the present invention relates to a coating composition containing a crosslinkable polyurethane emulsion, which is useful as a coating agent for a substrate such as metal, plastic, paper, wood, cement and leather.

[0002]

2. Description of the Related Art Polyurethane emulsions are widely used for paints, adhesives, and coating agents because they are excellent in film-forming property and give coating films 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 into the polyurethane emulsion a crosslinking system having both low temperature curability and storage stability. For example, it is possible to provide self-crosslinking polyurethane emulsions at low temperatures by incorporating hydrazide groups into the polyurethane chain and adding formaldehyde, US Pat. No. 4,598,812.
No. 1 proposed. However, the use of formaldehyde is toxic and environmentally undesirable, so it must be limited to specific applications.

In US Pat. No. 4,983,662,
A self-crosslinking polyurethane emulsion using a vinyl polymer having a carbonyl functional group or a non-vinyl-based polycarbonyl compound instead of formaldehyde has been proposed. However, according to this method, in order to introduce the hydrazide group in a suspended form in the polyurethane chain, not only complicated steps and special raw materials have to be used,
The hydrazide group cannot be effectively introduced to the particle surface of the polyurethane emulsion (that is, the crosslinking efficiency is poor), and the remaining hydrazide group-introducing raw material adversely affects the weather resistance and water resistance of the film.

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, in this method, since the hydrazine group is introduced only at both ends of the polyurethane chain, the total amount of hydrazine groups introduced is very small, so that the crosslinking efficiency becomes poor, and a sufficient effect for improving water resistance, solvent resistance, etc. can be obtained. Not not. Further, hydrazine and water-soluble dihydrazines used in this method are toxic and it is difficult to control the reaction with NCO groups. Therefore, the obtained aqueous polyurethane resin is toxic due to the above-mentioned residual hydrazine derivative, and the hydrazine group is not effectively introduced into the polyurethane.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a polyurethane emulsion-based aqueous coating composition that solves the above-mentioned problems of the prior art, that is, it has good storage stability and is water resistant even when used in a normal dry condition. The purpose of the present invention is to provide a polyurethane emulsion-based aqueous coating composition that exhibits sufficient physical properties in terms of solvent resistance and the like, and can form a film having a well-balanced hardness and elasticity.

[0007]

The present inventors have completed the present invention by using an aqueous coating composition comprising a specific hydrazide group-containing polyurethane emulsion and a polycarbonyl compound. That is, the present invention relates to the diisocyanate compound (a) and at least a number average molecular weight of 400 to 8000.
Urethane Prepolymer Having NCO Group Derived From Compound (b) Having Active Hydrogen Containing Polyols Of
0.5 to 100 parts by weight of the polyisocyanate compound (c)
After mixing 500 parts by weight, a polyurethane emulsion (A) obtained by reacting with a hydrazine derivative in the presence of water and a polycarbonyl compound (B) are included, and the solid content weight ratio is (A) / (B). = 100 / 0.1-5 /
The water-based coating composition is 100.

The present invention will be described in detail below. In the present invention, examples of the diisocyanate compound (a) used for synthesizing the urethane prepolymer having an NCO group include 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 And other aromatic diisocyanates, xylylene diisocyanates (XDI), phenylene diisocyanates and other aromatic alicyclic diisocyanates, and further 4,4′-methylenebiscyclohexyl diisocyanate (hydrogenated MDI), isophorone diisocyanate (IPDI), dimethylcyclohexane diisocyanate Alicyclic diisocyanates such as (hydrogenated XDI) and hexamethylene diisocyanate (H
Aliphatic diisocyanates such as DI) are mentioned.

In the present invention, the compound (b) having active hydrogen containing at least a number average molecular weight of 400 to 8,000 polyols used for synthesizing the urethane prepolymer having an NCO group has a number average molecular weight of 40.
In addition to 0-8000 polyols, polyhydric alcohols and / or polyhydric amines having a molecular weight of 400 or less, and a nonionic and / or ionic hydrophilic group (or a group which can be subsequently converted into a hydrophilic group) are used. The active hydrogen compound is selected as an optional component.

The number average molecular weight of the polyols is 400 to
It is 8,000, preferably 500 to 4000.
As the polyols, polycarbonate polyol,
Polyether polyols, polyester polyols, polybutadiene glycols, etc., which are used alone or
It can be used in combination of one or more kinds. Of these, polycarbonate polyols are preferable from the viewpoints of heat yellowing resistance, water resistance, solvent resistance, weather resistance and the like.

As the polycarbonate polyol, a product obtained by reacting a dihydric alcohol with a carbonate agent selected from phosgene, dialkyl carbonate, diallyl carbonate and alkylene carbonate in the presence or absence of a catalyst is used. 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-4-2526 are preferred from the viewpoint of flexibility and the like.
Amorphous polycarbonate polyols described in Japanese Patent Publication No. 4 and the like are preferable, and polytetramethylene carbonate diol produced in the presence of an acidic substance in view of solvent resistance, hardness and the like (see Japanese Patent Application No. 4-258748). The method described) is preferred.

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 random). (Block) glycol, polyoxypropylene-oxytetramethylene (random and / or block) glycol, polyhexamethylene glycol, and the like, and a combination of two or more thereof.

Specific examples of polyester polyols 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, 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.

In order to further improve the properties such as the heat softening temperature, the flexibility and the hardness of the obtained polyurethane, the molecular weight of the compound (b) having the active hydrogen of the present invention is usually 400 if necessary. The following compounds having low-molecular active hydrogen are preferably used in combination. Specific examples thereof include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,3-pentanediol, Dihydric alcohols such as 1,6-hexanediol, hydrogenated bisphenol A and cyclohexanedimethanol, trihydric or higher alcohols such as glycerin, trimethylolpropane and pentaerythritol, amino alcohols such as monoethanolamine and diethanolamine, Aliphatic amines such as ethylenediamine, hexamethylenediamine, diethylenetriamine, isophoronediamine, 4,4-methylenebis (cyclohexylamine)
Alicyclic amines and the like, and combinations of two or more of these.

If necessary, a part of the compound (b) having active hydrogen of the present invention may be a compound having a nonionic and / or ionic hydrophilic group (or a group which can be converted into a hydrophilic group later). When used in combination, the resulting polyurethane can be made into a self-emulsifying type. The self-emulsifying type is preferable because it improves the dispersion stability of the polyurethane emulsion and the water resistance of the film obtained therefrom.

Examples of the ionic hydrophilic group include anionic groups such as tertiary amine salts of carboxylic acids and cationic groups such as quaternary ammonium salts. Examples of the compound having an anion group (or a group which can be subsequently converted into an anion group) include
α, α′-dimethylolpropionic acid, α, α′-dimethylolacetic acid, α, α′-dimethylolbutyric acid, α, α ′
-Α, α'-dimethylolalkanoic acids such as dimethylolvaleric acid, aminosulfonic acids such as taurine, and the like, and combinations thereof. Of these, α, α'-dimethylolpropionic acid is preferred. The acid group of these compounds having active hydrogen can be converted into an anionic group by neutralizing with a base during synthesis of the urethane prepolymer or during emulsification. Examples of the base used for neutralization include amine compounds such as triethylamine, ammonia, diethanolamine, dimethylaminoethanol, methyldiethanolamine, dibutylamine, KOH, Na
Examples thereof include alkali metal hydroxides such as OH and LiOH, and combinations thereof.

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

Examples of the nonionic hydrophilic group include a pendant polyoxyalkylene group, particularly a polyoxyethylene group. Examples of compounds having these groups include diols having a suspended polyoxyethylene chain as described in US Pat. No. 3,905,929. The urethane prepolymer of the present invention is obtained by subjecting (a) and (b) to a urethanization reaction at a temperature of 30 ° C to 130 ° C under substantially anhydrous conditions. The equivalent ratio of the NCO group of the diisocyanate compound (a) used when producing the urethane prepolymer to the active hydrogen group capable of reacting with the NCO group in the compound (b) having active hydrogen is usually 1.1 to 5.0. : 1.0, preferably 1.1 to 2.0: 1.0.

In producing the urethane prepolymer, a catalyst can be used if necessary. As the catalyst, 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 diazabicycloundecene. A system etc. are mentioned.

The urethane prepolymer can be produced without a solvent or in a solvent. As this solvent, one that is inactive to the NCO group or 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 solvent such as toluene xylene, n-hexane And the like, and combinations thereof. Among these, acetone, methyl ethyl ketone, N-
Methyl-2-pyrrolidone is particularly preferred. The solvent may remain in the polyurethane emulsion, but it can also be distilled off by heating under normal pressure or reduced pressure after forming the emulsion.

In the present invention, N obtained by the above-mentioned method
After mixing the polyisocyanate compound with the urethane prepolymer having a CO group, it is important to use it for the next reaction. That is, this makes it possible to increase the amount of hydrazide groups introduced into the polyurethane emulsion and the degree of internal cross-linking, which in turn improves the water resistance of the film produced by cross-linking with the polycarbonyl compound and the balance between hardness and elasticity. Can be achieved. Further, it is not appropriate to mix the polyisocyanate compound during the synthesis of the urethane prepolymer. Because, when trying to fully exert the effect of the polyisocyanate compound,
This is because the method in which the urethane prepolymer is mixed at the time of synthesizing the urethane prepolymer significantly increases the viscosity of the urethane prepolymer and causes gelation, so that it cannot be used in the next reaction.

As the polyisocyanate compound, 1,
8-diisocyanato-4-isocyanatomethyloctane, and further, the diisocyanate compound exemplified as the raw material (a) of the urethane prepolymer was oligomerized by a buret bond, a urea bond, an isocyanurate bond, a urethane bond, an allophanate bond, a uretdione bond, or the like. And combinations thereof.

NC of these polyisocyanate compounds
The O group is 1 to 50 wt%, preferably 5 to 30 w
t%. The polyisocyanate compound is mixed in an amount of 0.5 to 500 parts by weight, preferably 5 to 100 parts by weight, based on 100 parts by weight of the urethane prepolymer. If the amount of the polyisocyanate compound is less than 0.5 parts by weight, the effect of the polyisocyanate compound cannot be sufficiently exhibited, and if it is more than 500 parts by weight, the flexibility of the polyurethane is impaired.

The polyurethane emulsion (A) in the present invention is obtained by reacting the mixture of the urethane prepolymer having an NCO group obtained by the above-mentioned method and the polyisocyanate compound with a hydrazine derivative in the presence of water. At this time, the equivalent ratio of the total NCO groups of the mixture of the urethane prepolymer and the polyisocyanate compound to the active hydrogen groups of the hydrazine derivative is usually 1.0: 0.3 to
2.0, preferably 1.0: 1.0 to 2.0.

Examples of the hydrazine derivative include hydrazine; water-soluble dihydrazines such as ethylene-1,2-dihydrazine, propylene-1,3-dihydrazine and butylene-1,4-dihydrazine; and hydrazide groups. Examples thereof include polyhydrazide compounds having at least two in the molecule. Among these, polyhydrazide compounds are preferable from the viewpoint of easy control of reactivity with NCO group and toxicity.

As the polyhydrazide compound, 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 dihydrazide,
Dicarboxylic acid dihydrazides such as isophthalic acid dihydrazide and phthalic acid dihydrazide, tricarboxylic acid trihydrazides such as trimellitic acid trihydrazide, carbonic acid dihydrazides represented by the general formula (1), and bissemicarbazide represented by the general formula (2). And the like, and combinations thereof.

[0028]

[Chemical 1]

[0029]

[Chemical 2]

These polyhydrazide compounds have an appropriate hydrophilicity because if they are too hydrophobic, they will not disperse in water and the reaction of the mixture of the urethane prepolymer and the polyisocyanate compound in the presence of water will be difficult. Preference is given to using the compounds having. Suitable representative examples include, for example, adipic acid dihydrazide, succinic acid dihydrazide, sebacic acid dihydrazide, carbodihydrazide and the like.

In the hydrazine derivative, if necessary, at least a part of the hydrazide group or the hydrazine group may be previously prepared with a monoaldehyde or monoketone (preferably 30 parts).
It can also be used by blocking with a hydrazone group by reacting with, for example, acetone, methyl ethyl ketone) having a boiling point of ˜200 ° C. In the present invention, the method of reacting the hydrazine derivative in the mixture of the urethane prepolymer and the polyisocyanate compound in the presence of water is carried out by adding an aqueous solution of the hydrazine derivative to the mixture of the urethane prepolymer and the polyisocyanate compound under appropriate stirring. Method. A method in which water is added to a mixture of a urethane prepolymer and a polyisocyanate compound with appropriate stirring to form a dispersion, and then an aqueous solution of a hydrazine derivative is added to react. Examples include a method in which a mixture of a urethane prepolymer and a polyisocyanate compound is added to an aqueous solution of a hydrazine derivative under appropriate stirring and the mixture is reacted. the above~
In any of the above methods, a surfactant may be added at any stage for the purpose of assisting or adding the dispersibility and dispersion stability of the mixture of the urethane prepolymer and the polyisocyanate compound, 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 the hydrazine derivative is reacted with the mixture of the urethane prepolymer and the polyisocyanate compound in the presence of water, a chain extender may be used together with the hydrazine derivative if necessary. As the chain extender, ethylenediamine, propylenediamine, hexamethylenediamine, tolylenediamine, xylylenediamine, diphenyldiamine, diaminodiphenylmethane, diaminocyclohexylmethane, piperazine, 2-methylpiperazine, isophoronediamine, and various other diamines, diethylenetriamine And the like, and combinations thereof.

The concentration of the resin component of the polyurethane emulsion (A) thus obtained can be 0.1 to 95 wt%, but 10 to 50 wt% is preferable in terms of production. In addition, various additives may be added to the polyurethane emulsion (A) for the purpose of improving weather resistance and the like, if necessary. When an additive is used, it is usually added at the time of synthesizing the urethane prepolymer, but when the additive is water-soluble or reacts with a reaction component such as an isocyanate component, it is preferably added as a dispersion. As additives, hindered phenol type, phosphite type,
Thioether-based antioxidants, benzophenone-based, benzotriazole-based, salicylate-based UV absorbers, hindered amine-based light stabilizers, organic halogen-based flame retardants and antistatic agents, water repellents, and the like, and These can be used in combination.

In the present invention, by mixing the polyurethane emulsion (A) thus obtained with the polycarbonyl compound (B), a functional bond is strongly developed. It is considered that this binding is caused by the organic reaction between the hydrazine functional group and / or the hydrazone functional group in the polyurethane emulsion (A) and the carbonyl group in the polycarbonyl compound (B) when forming a film. .

The polycarbonyl compound (B) is a compound having two or more carbonyl groups, for example, polyketones such as glyoxal, 2,5-hexanedione and acetylacetone, polyglutones such as glutardialdehyde and succinic dialdehyde. Aldehydes, JP-A-2-23801
No. 5, but not limited to carbonyl group-containing polyurethanes prepared from mono- and / or polyalcohols having a carbonyl group such as hydroxyacetone, as disclosed in JP-A-63-51180 and JP-A-62-72742. Publication, Japanese Patent Publication No. 1-15011, Japanese Patent Publication No. 1-454
A carbonyl group-containing ethylenically unsaturated monomer such as diacetone acrylamide, diacetone methacrylamide, acrolein, vinyl methyl ketone, and acetoacetoxyethyl methacrylate, as described in Japanese Patent Application Laid-Open No. 97, Japanese Patent Application Laid-Open No. 4-214747 and the like. And copolymer aqueous emulsions containing as a copolymerization component, and combinations thereof. These polycarbonyl compounds (B)
Among them, copolymer aqueous emulsions containing a carbonyl group-containing ethylenically unsaturated monomer as a copolymerization component are preferable from the viewpoint of the balance of hardness and elasticity of the film formed by the polyurethane emulsion (A) in the present invention. Further, from the viewpoint of weather resistance, obtained by copolymerizing an ethylenically unsaturated monomer containing a carbonyl group with another ethylenically unsaturated monomer in the presence of a hydrolyzable silane described in JP-A-4-214747. Copolymer aqueous emulsions are preferred.

In the present invention, the blending ratio of the polyurethane emulsion (A) and the polycarbonyl compound (B) is
The solid content weight ratio is (A) / (B) = 100 / 0.1
Within the range of 5/100 is a requirement of the present invention.
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 aqueous coating composition of the present invention may optionally contain a pigment, a filler, a dispersant, a wetting agent, a thickener, a rheology control agent, an antifoaming agent, a plasticizer, a film-forming aid, an anticorrosive 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.

[0038]

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 is 100% after the sample film is immersed in ion-exchanged water at room temperature for 1 week and then dried at room temperature for 1 day.
The elongation modulus retention rate was calculated by the following equation (1). Retention of 100% elongation modulus = M ₂ / M ₁ × 100 (1) where M ₂ is 100% elongation modulus (K
g / cm ² ) and M ₁ are 100% elongation modulus before immersion in water (Kg / cm ² ). The solvent resistance was determined by placing the sample film in a 200-mesh wire mesh bag, immersing the sample film in acetone at room temperature for 24 hours, and then determining the retention rate of the film weight by the following formula (2). Weight retention = S ₂ / S ₁ × 100 (2) where S ₂ is the film weight after immersion in acetone (g), S
₁ is the film weight (g) before immersion in acetone.

Production Example of Polyurethane Emulsion (A) 1063 parts of polytetramethylene glycol (PTMG) having a hydroxyl value of 57.3, 363 parts of isophorone diisocyanate (IPDI), and triethylamine (TEA) 5
5 parts, dimethylolpropionic acid (DMPA) 73 parts,
1554 parts of methyl ethyl ketone (MEK) and 0.04 part of dibutyltin dilaurate (BTL) were placed in a reactor equipped with a reflux condenser, a thermometer and a stirrer, and heated at 80 ° C. for 6 minutes.
The urethane reaction was carried out for an hour to obtain an NCO-terminated prepolymer solution. "Duranate TPA" as a polyisocyanate compound was added to the prepolymer solution adjusted to 30 ° C.
(Asahi Kasei Co., Ltd., hexamethylene diisocyanate isocyanurate type oligomer (NCO group content 2
3.1 wt%)) in an amount of 311 parts, and while stirring 5380 parts of a 5.7% adipic acid dihydrazide aqueous solution, about 30 parts are added.
Added over 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, and the solid content was 30% and the viscosity (B Type viscometer, No1, 60
rpm, 20 ° C) 36 cps, particle size 1440, pH
A polyurethane emulsion (A-1) of 7.8 was obtained.

In the same manner as above, using the raw materials shown in Table 1, polyurethane emulsions (A-2) and (A-3) having the properties shown in Table 1 were prepared. 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.

[0042]

Examples 1 to 3 and Comparative Examples 1 to 6 The polyurethane emulsion (A) obtained in each production example and the polycarbonyl compound (B) were blended as shown in Table 2. All of the aqueous coating compositions had good storage stability with little change in viscosity even after storage at 40 ° C. for 1 month. Further, the physical properties of the film were tested by using each of the aqueous coating compositions alone. The results are shown in Table 2.

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

The water-based coating composition of the present invention not only has excellent storage stability, but also exhibits sufficient physical properties in terms of water resistance, solvent resistance, etc. even when it is used in an ordinary dry state, and has a balance between hardness and elasticity. A clear film can be obtained. Therefore, according to the present invention, a clear coat agent, a top coat agent, a paint, an undercoat agent, an impregnating agent for cloth or paper,
Provided is an excellent aqueous coating composition which can be used for various applications as various adhesives and the like.

Claims (1)

[Claims] 1. An NCO derived from a diisocyanate compound (a) and a compound (b) having active hydrogen containing at least a polyol having a number average molecular weight of 400 to 8000.
Polyurethane emulsion (A) obtained by mixing 0.5 to 500 parts by weight of a polyisocyanate compound (c) with 100 parts by weight of a urethane prepolymer having a group, and then reacting with a hydrazine derivative in the presence of water; Compound (B), the solid content weight ratio of which is (A) /
(B) = 100 / 0.1-5 / 100, The aqueous coating composition characterized by the above-mentioned.