JPH10219194A - Water-base coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a water-base coating material which has a low risk to cause environmental pollution and fire during coating, can be simply and easily stored and applied, and gives a film excellent in physical properties and having high gloss by blending an aqueous resin dispersion comprising a vinyl polymer having self-dispersibility in water, and a water-soluble organic solvent having a solubility in water and a boiling point each in a specified range, each in a specified amount. SOLUTION: The vinyl polymer having self-dispersibility in water is obtained by using at least 65wt.% non-functional (meth)acrylic ester having a 4-12C hydrocarbon group or mixture of this ester with an aromatic vinyl monomer, and 3-6wt.% mixture of a nonfunctional unsaturated monomer having a polyethylene glycol group with an α,β-ethylenically unsaturated carboxylic acid at a weight ratio of (1 to 5):1. An aqueous resin dispersion comprising this vinyl polymer is blended with an organic solvent having a boiling point under ordinary pressure of about 130-220 deg.C and a solubility in water at 20 deg.C of at least 100. The amount of the organic solvent blended is at least 20wt.% based on the solids of the dispersion and at most 15wt.% in the coating material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a new and useful aqueous coating composition. More specifically, the present invention is based on an aqueous dispersion consisting of an aqueous resin dispersion of a vinyl polymer with a low solvent content, of a specific composition ratio, in particular with a low organic solvent content, The present invention relates to an extremely practical water-based coating composition which is excellent in gloss and excellent in various physical properties of a coating film.

[0002]

2. Description of the Related Art Various water-based paints have been studied as a countermeasure against environmental pollution. However, these water-based paints are based on emulsion polymers and water-soluble paints. It can be broadly classified into those based on so-called colloidal dispersion, in which the resin is self-emulsified and dispersed or dissolved in the presence of a solvent.

Conventionally, however, the former type of water-based paint based on an emulsion polymer has a lower organic solvent content, but has a process of forming a film by fusing resin particles together. In the above, the smoothness of the coating film surface is impaired, and thus the gloss is impaired, and as a result, it is difficult to obtain a coating film having good stain resistance and the like, and in addition, the emulsifier contained therein , The foamability of the coating material is increased, and the water resistance of the coating film and the adhesion to the base material are inferior.

[0004] On the other hand, in the case of the latter type of water-based paint based on colloidal dispersion, the smoothness of the coating film surface is more easily improved than that of the former type, which is based on an emulsion polymer. Compared with those based on solvent-based resins, it is generally inferior, and in order to further improve the smoothness of the coating film surface, it is necessary to increase the water-soluble solvent content,
Therefore, it is an unfavorable paint in terms of environmental pollution prevention measures.

Further, due to polar groups such as a carboxyl group introduced for obtaining self-emulsifying dispersibility, it was difficult to obtain desired coating properties such as sufficient water resistance and alkali resistance.

[0006] Among the various performances of the coating film, the smoothness of the dried coating film is important not only from the viewpoint of high aesthetics of high gloss but also from the viewpoint of preventing contamination of the coating film after coating. Needless to say, performance.

[0007] That is, a water-based paint having a very high practicality that has a low acid value, a low solvent content, and a coating film having high gloss and good water resistance can be obtained. However, as far as the conventional technology is concerned, it is impossible to obtain it at all.

[0008]

SUMMARY OF THE INVENTION In view of the above-mentioned various disadvantages of the prior art, the present inventors have developed an aqueous resin dispersion of a vinyl polymer having a low solvent content. Based on aqueous dispersion,
Above all, intense research has been started in search of an extremely practical aqueous coating composition that has a low organic solvent content, is excellent in the gloss of the coating film, and is also excellent in various physical properties of the coating film. .

[0009] Therefore, the problem to be solved by the present invention is, on the one hand, to have excellent coating properties comparable to solvent-based paints, high gloss and high organic solvent content. An object of the present invention is to provide a water-based paint for drying at room temperature or forcibly drying.

[0010]

Means for Solving the Problems Accordingly, the present inventors have:
As a result of diligent and intensive studies to solve the various unresolved problems of the conventional technology, a vinyl polymer having a specific composition, especially an acrylic polymer, a specific type and its amount The organic solvent is a specific water-based paint that contains as an essential component, environmental pollution and less dangers such as fire at the time of painting, can be easily stored and installed, and moreover The present invention has been completed here by finding that it shows excellent coating properties and high gloss, which are unprecedented.

That is, the present invention basically comprises, in part, a non-functional (meth) acrylate (a-1) having a hydrocarbon group having 4 to 12 carbon atoms, or A non-functional (meth) acrylates and an aromatic vinyl monomer (a-2), a monofunctional unsaturated monomer having a polyethylene glycol group (b), and α,
The β-ethylenically unsaturated carboxylic acid (c) is used, and among the total polymerizable unsaturated monomers, the monomer (a-
The sum of the monomer (b) and the monomer (c) obtained by using 1) or (a-2) in an amount of 65% by weight or more is 3%.
A vinyl polymer having a self-water dispersibility in a range of 1 to 6% by weight and a weight ratio of the monomer (b) / the monomer (c) in a range of 1 to 5; The essential components are an aqueous resin dispersion (A) and an organic solvent (B) having a boiling point under normal pressure of about 130 to about 220 ° C and a water solubility at 20 ° C of 100 or more. The organic solvent (B) contains about 20% by weight or more based on 100 parts by weight of the solid content of the aqueous resin dispersion (A). An aqueous coating composition comprising less than about 15% by weight of total organic solvent,

The second is that the above-mentioned non-functional (meth) acrylates (a-1), or these non-functional (meth) acrylates and aromatic vinyl monomers (A-2), the above-mentioned monofunctional unsaturated monomer (b), and the above-mentioned α, β-ethylenically unsaturated carboxylic acid (c), and a total polymerizable unsaturated monomer All over the body,
The above monomer (a-1) or (a-2) is converted to 65
By weight of at least 3% by weight of the monomer (b) and the monomer (c), and
The weight ratio of the monomer (b) / the monomer (c) is 1
An aqueous resin dispersion (A) having a self-water dispersing ability in a range of from about 5 to about 5;
Water solubility at 20.degree.
The above organic solvent (B) and the curing agent (C) are essential components, and the above organic solvent (B) is added to the aqueous resin dispersion (A) in an amount of about Another object of the present invention is to provide an aqueous coating composition containing not less than 20% by weight, and the total amount of organic solvents in the obtained aqueous coating composition is about 15% by weight or less. ,

More specifically, each of the above-mentioned aqueous resin dispersions (A) has a gel permeation.
The number average molecular weight was about 8,000 in terms of the molecular weight in terms of polystyrene by chromatography (GPC).
From about 20,000 to about 20,000, the weight average molecular weight is from about 15,000 to about 50,000, and the acid value in terms of solid content is from about 3 to about 18 mg KO.
It is also intended to provide a specific aqueous coating composition which is within the range of H / g, and two of the above-mentioned aqueous resin dispersions (A) The hydroxyl value in terms of solid content of about 30 to about 120 mg KO
It is also intended to provide a specific aqueous coating composition in the range of H / g, and three is that the above-mentioned curing agent (C) is a polyisocyanate compound, and The isocyanate compound is blended with the above aqueous resin dispersion (A) in an equivalent ratio of NCO group / OH group within a range of about 0.5 to about 2 in a specific amount. It is also intended to provide an aqueous coating composition.

[0014]

As described above, in the present application, the number of carbon atoms is four.
(A) a non-functional (meth) acrylate having a hydrocarbon group of from 1 to 12 or a non-functional (meth) acrylate and an aromatic vinyl monomer (a -2), a monofunctional unsaturated monomer having a polyethylene glycol group (b), and an α, β-ethylenically unsaturated carboxylic acid (c), and a fully polymerizable unsaturated monomer. In the above, the monomer (a-1) or (a
-2) in an amount of 3 to 6% by weight obtained by using 65% by weight or more of the monomer (b) and the monomer (c), and an aqueous resin dispersion (A) of a vinyl polymer having self-water dispersibility having a weight ratio of b) / the monomer (c) in the range of 1 to 5; An organic solvent (B) having a solubility in water within a range of 130 to about 220 ° C. and 20 ° C. of 100 or more as an essential component;
Is contained in an amount of about 20% by weight or more based on 100 parts by weight of the solid content of the aqueous resin dispersion (A), and the total amount of the organic solvent in the obtained aqueous coating composition is about 1%.
Claiming an aqueous coating composition comprising no more than 5% by weight;

In addition, the present invention relates to a non-functional (meth) acrylic ester (a-1) having a hydrocarbon group having 4 to 12 carbon atoms, or a non-functional (meth) acrylic ester thereof. Acid esters and aromatic vinyl monomers (a-
2), a monofunctional unsaturated monomer having a polyethylene glycol group (b), and an α, β-ethylenically unsaturated carboxylic acid (c). And the above monomer (a-1) or (a-2)
When the sum of the monomer (b) and the monomer (c) obtained by using 65% by weight or more is within a range of 3 to 6% by weight, and the monomer (b) / the monomer An aqueous resin dispersion (A) having a self-water dispersing ability in which the weight part ratio of the monomer (c) is in the range of 1 to 5, and a boiling point under normal pressure of about 130 to about 22
Within the range of 0 ° C., and the solubility of water at 20 ° C. is 1
The organic solvent (B) and the curing agent (C) are essential components, and the organic solvent (B) is added to the aqueous resin dispersion (A) based on 100 parts by weight of the solid content. About 2
Claims are also directed to an aqueous coating composition containing at least 0% by weight, and having a total organic solvent content of about 15% by weight or less in the obtained aqueous coating composition. ,

Further, in the present application, the above-mentioned aqueous resin dispersion (A) has a number average molecular weight of about 8,000 to about 20 in terms of polystyrene equivalent molecular weight by gel permeation chromatography (GPC). ,
000 and a weight average molecular weight of about 15,
The present invention also claims a specific aqueous coating composition having an acid value in the range of 000 to about 50,000 and an acid value in terms of solid content of about 3 to about 18 mgKOH / g. And

Further, the present invention relates to the aqueous resin dispersion (A) described above, in particular, each having a number average molecular weight of about 8,000 to about 8,000 in terms of polystyrene conversion molecular weight by GPC.
The aqueous resin dispersion (A) has a hydroxyl value in terms of solid content of about 20,000 and a weight average molecular weight of about 15,000 to about 50,000. It is in the range of 30 to about 120 mgKOH / g, and a polyisocyanate compound is used as the above-mentioned curing agent (C), and the polyisocyanate compound has an NCO group relative to the aqueous resin dispersion (A). / OH
It is also claimed that certain aqueous coating compositions are formulated to be in the range of about 0.5 to about 2 at the base equivalent ratio.

Hereinafter, the present invention will be described in more detail.

First, the aqueous resin dispersion (A) described above needs to have a specific monomer composition as the aqueous resin dispersion (A). One is that non-functional (meth) acrylates having a hydrocarbon group having 4 to 12 carbon atoms are used. The (meth) acrylates, that is, (meth) ) Acrylates are components essential for improving, among other things, the water resistance, chemical resistance and weather resistance of the resulting coating film.

These (meth) acrylic esters,
In other words, various compounds are used as the (meth) acrylates. Among them, if only typical ones are exemplified, normal (n-) butyl (meth) acrylate and iso (i) -) Butyl (meth) acrylate, tert-butyl (meth) acrylate,
Examples thereof include 2-ethylhexyl (meth) acrylate or lauryl (meth) acrylate or cyclohexyl (meth) acrylate or benzyl (meth) acrylate, which are used as one kind or as a mixture of two or more kinds.

Here, when the (meth) acrylic acid ester having a hydrocarbon group having more than 12 carbon atoms is used, the obtained coating film, in particular, the adhesion to the substrate and the like is deteriorated. Is not preferred.

In addition, styrene, vinyltoluene, p-tert-butylstyrene and the like may be mentioned only as typical examples of the aromatic vinyl monomer. The monomers themselves are used as needed, in particular for improving the coating, in particular the chemical resistance and the like.

The amount of these aromatic vinyl monomers to be used is determined based on the total amount of the monomers, that is, based on the total amount of the monomers, in consideration of the balance of various physical properties of the resulting coating film.
Desirably less than about 40% by weight.

The combination of the above-mentioned non-functional (meth) acrylic acid esters with an aromatic vinyl compound (a-
As the amount of 2), as the sum of the amounts of these two monomers,
About 6% of all monomers, that is, based on the total amount of monomers
It is necessary that it be at least 5% by weight.

Next, the monofunctional unsaturated monomer (b) having a polyethylene glycol group will be described. Particularly typical examples of the monofunctional unsaturated monomer (b) are as follows. By way of example only, mono (meth) acrylate of polyethylene glycol, or a compound in which the terminal hydroxyl group thereof is blocked with a so-called alkoxyl group such as a methoxy group or an ethoxy group, etc.

Further, as the monomer (b), specifically, “Blemmer PME400, PME4
000, AE350 or PE350 "[the above products are products of NOF Corporation]," NK ester M-90G or M-230G "[the above products are products of Shin-Nakamura Chemical Co., Ltd.] or" NF Visomer S-10W " , S-20W,
MPEG350MA or PEM6E "[the above are products of Daiichi Kogyo Seiyaku Co., Ltd.].

These monomers (b) are mainly
The aqueous resin dispersion (A), in particular, improves the hydrophilicity and the like, and thus, not only improves the water dispersibility of the aqueous resin dispersion (A), but also improves the pigment dispersibility,
Furthermore, in order to improve the water retention, especially, by delaying the surface drying property of the resulting coating film,
It is an essential component that contributes to the development of high gloss.

In terms of the molecular weight of the above-mentioned polyethylene glycol group in the monofunctional unsaturated monomer (b), the polyethylene glycol is one having an ethylene oxide 3 mol adduct or less, that is,
When it comes to using a compound in a form in which less than or equal to mol of ethylene oxide is added, the effect of improving the hydrophilicity, pigment dispersibility and water retention, respectively, as described above, tends to be low, On the other hand, when a compound having an ethylene oxide addition of 50 mol or more, that is, a compound in which about 50 mol or more of ethylene oxide is added is used, inevitably, the obtained coating film, especially the adhesion to the substrate, etc. Care must be taken, as it tends to decrease.

In the case of a non-crosslinked paint, there is no difference between a paint having a terminal hydroxyl group and a paint having a blocked alkoxyl group, and any of them can be used. In the case of paint,
It is more desirable to use one having a terminal hydroxyl group from the viewpoint that the crosslinking reaction becomes faster.

Next, the above-mentioned α, β-ethylenically unsaturated carboxylic acid (c) will be described. The monomer (c) is particularly hydrophilic with respect to the aqueous resin dispersion (A). Properties, to improve the aqueous dispersion stability and pigment dispersibility, from the point of giving the substrate adhesion of the resulting coating film, etc., is essential for the aqueous coating composition according to the present invention. A component,

If only typical examples of the α, β-ethylenically unsaturated carboxylic acid (c) are given as examples, examples thereof include (meth) acrylic acid and crotonic acid, and further, fumaric acid. Various unsaturated dicarboxylic acids, such as, maleic acid, itaconic acid or citraconic acid;
Alternatively, these are monoalcohol esters of dicarboxylic acids and the like, and these are used as one kind or as a mixture of two or more kinds.

The above-mentioned monofunctional unsaturated monomers (b) each having a polyethylene glycol group and α, β
-The amount used with the ethylenically unsaturated carboxylic acid (c) is to be determined in view of the properties of the resulting coating film, in particular, the coating film properties such as gloss, water resistance and alkali resistance, Monomer (b) in all monomers
And the sum of the amounts of the monomers (c) used is in the range of about 3 to 6% by weight, and the weight ratio of monomer (b) / monomer (c) is about It is preferably in the range of 1 to 5.

If the sum of the amounts of the monomers (b) and (c) becomes too large, exceeding about 6% by weight, it is inevitable that the resulting coating film, especially However, if the total is less than about 3% by weight, the resin, especially the water dispersibility, is inferior. Either case is not preferable because it becomes easier.

When the ratio by weight of the monomer (b) / monomer (c) is less than about 1, the obtained coating material tends to be insufficient due to insufficient water retentivity. And, consequently, it is easy to obtain a high gloss coating film,
On the other hand, if the ratio by weight exceeds about 5, the resin, especially the pigment dispersibility, the adhesion of the obtained paint to the base material, and the like become inferior.

As the aqueous resin dispersion (A), the solid content of the aqueous resin dispersion (A) is particularly preferable in terms of water resistance, alkali resistance and substrate adhesion. Diacid value is about 3 to about 18mgKOH / g
Is suitably within the range, preferably from 6 to 15
A range of mgKOH / g is appropriate.

In addition, only other typical polymerizable unsaturated monomers that can be copolymerized are exemplified as methyl (meth) acrylate, ethyl (meth) acrylate, and n. Various (meth) acrylates ((meth) acrylates) having an alkyl group having 3 or less carbon atoms, such as -propyl (meth) acrylate or i-propyl (meth) acrylate;

Various vinyl esters such as vinyl acetate, vinyl benzoate or "Veoba" (trade name of vinyl versatate, Shell Co., Netherlands); perfluorocyclohexyl (meth) acrylate or di-perfluoro Various perfluoroalkyl group-containing monomers such as cyclohexyl fumarate; various cyano group-containing monomers such as (meth) acrylonitrile;

Various (halogenated) olefins such as ethylene or propylene or vinyl chloride, vinylidene chloride or vinyl fluoride; glycidyl (meth)
Various amide bond containing monomers, such as acrylate, (meth) acrylamide or N-methylol (meth) acrylamide;

Alternatively, (meth) acryloyloxyalkyl acid phosphate, N, N-dimethylaminoethyl (meth) acrylate, methacryloxypropyltrimethoxysilane, alkoxylated polypropylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate , 2-hydroxyethyl (meth)
Including acrylate, 2-hydroxypropyl (meth) acrylate or hydroxybutyl (meth) acrylate,

Further, it may be, for example, di-2-hydroxyethyl fumarate or the like, polyethylene glycol (meth) acrylate having a molecular weight of less than about 250 and having a polyethylene glycol group, or cyclohexyldimethanol mono (meth) acrylate. Such as

Further, "Placcel FM or F
E monomers "(trade names of ε-caprolactone-added monomers manufactured by Daicel Chemical Co., Ltd.) and the like, and of course, the present invention is not limited to these examples. It is by no means limited to the examples shown.

In particular, the above-mentioned (meth) acrylates do not at all hinder the use of polymerizable unsaturated monomers having a hydrocarbon group having more than 12 carbon atoms. These various copolymerizable unsaturated monomers, in the resulting coating film, in particular, for the purpose of improving the hardness, pigment dispersibility and adhesion to the substrate, among all the monomers, that is, The amount is appropriately selected and used in an amount of about 32% by weight or less based on the total amount of all monomers.

The molecular weight of the aqueous resin dispersion (A) is determined based on the balance of durability and film forming property of the resulting coating film, the balance of the viscosity of the aqueous resin dispersion, and the like. In terms of molecular weight in terms of polystyrene by gel permeation chromatography,
Suitably, the number average molecular weight is in the range of about 8,000 to about 20,000, and more preferably, the weight average molecular weight is in the range of about 15,000 to about 50,000.

The method of polymerizing the aqueous resin dispersion (A) is, of course, not particularly limited, but may be carried out in the presence of a part or all of a water-soluble organic solvent (B) as described later. It is desirable in the process that the solution polymerization is carried out and then the dispersion is carried out in water or the dispersion polymerization is carried out in the coexistence of the organic solvent (B) and water.

Further, the glass transition point (Tg) of the aqueous resin dispersion (A) is also not particularly limited, and is determined in consideration of the base material, the application, the drying method, the coating composition and the like. The theoretical Tg of a non-crosslinked paint is about 4 from the balance of stain resistance, water resistance and toughness.
The range of 0 to about 80 ° C. is appropriate, while the range of about 10 to about 60 ° C. is appropriate as the theoretical Tg in the case of a so-called cross-linked paint of the polyisocyanate compound combination type. .

Further, the carboxyl group in the aqueous resin dispersion (A) is a volatile basic substance from the viewpoint of the paint, especially the stability and the pigment dispersibility. It is desirable that the basic substance is a typical one such as ammonia, triethylamine, monoethanolamine, diethanolamine, dimethylethanolamine or 2-amino acid. -2-methyl-
The present invention is in no way limited to only these illustrative examples, such as 1-propanol.

However, by using a polyisocyanate compound as the curing agent (C),
In the case of crosslinking, it is better to avoid using a basic substance containing a reactive hydrogen atom such as ammonia. In addition, it is a matter of course that excessive use should be refrained from the fact that these basic substances become volatile organic solvents and may cause odor.

Next, the above-mentioned organic solvent (B) which is another essential component of the aqueous coating composition according to the present invention.
In the first place, the organic solvent (B) is distributed in the aqueous resin composition according to the present invention in the particles of the aqueous resin dispersion (A) and the aqueous phase. In particular, while improving the film forming property of the aqueous resin dispersion (A),
By delaying the drying property of the coating film surface to develop high gloss and further mixing with water, the surface tension of the obtained paint is lowered, dispersibility of the pigment, wettability of the paint to the base material, etc. It is an essential component also in the sense of improving the coating workability and, in turn, the coating workability and the adhesion of the coating film to the substrate.

From this point of view, the organic solvent (B) should be selected from both the sufficient hydrophilicity and the optimum boiling point range. It is absolutely necessary that the solubility of water at 20.degree. In that respect, solvents with water solubility less than 100,
In general, although the swelling effect of the resin particles is high, it is difficult to obtain a high gloss coating film.Therefore, it is necessary to use a large amount of a solvent, and as a result, environmental protection measures must be taken. Which is not desirable.

On the other hand, it is absolutely necessary that the boiling point of the latter is in the range of about 130 to about 220 ° C. at normal pressure. At that point, the boiling point is about 130
If the temperature is lower than 0 ° C., it is easy to volatilize with water as a main solvent during the drying process of the coating film, and thus it is difficult to obtain a coating film having both high smoothness and gloss. So it is not preferable,

On the other hand, if the boiling point exceeds about 220 ° C. and becomes too high, the organic solvent tends to remain in the coating film even after the coating film is formed. It is also not preferred from the viewpoint that the softening of the film tends to cause the contamination of the coating film and the decrease in the initial water resistance of the coating film.

If only typical examples of the organic solvent (B) are given as examples, 3-methoxybutanol, 3-methoxy-3-methylbutanol, ethylene glycol monoethyl ether, ethylene glycol mono (n- Or i-) propyl ether, ethylene glycol mono (n-, i- or tert-) butyl ether,

Diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono (n- or i-) propyl ether or propylene glycol mono (n-, i- or tert-) butyl ether ,

Alternatively, it is dimethylformamide, N-methylpyrrolidone or ethylene glycol methyl ether acetate. Of course, the present invention is by no means limited to these illustrative examples. These solvents are mainly used in consideration of the coating (drying) conditions and the solubility and solubility of the aqueous resin dispersion (A) based on the composition and molecular weight, respectively.
The species or a mixture of two or more species is appropriately selected and used.

The amount of the organic solvent (B) used is desirably about 20% or more based on 100 parts by weight of the solid content of the aqueous resin dispersion (A). If the amount used is less than about 20% by weight, the effect of the use of the organic solvent (B) will not necessarily be sufficient.

The content of the organic solvent (B) in the obtained paint is determined from the viewpoint of prevention of various disasters such as burning of the paint and the like, and measures against environmental pollution, including the organic solvent (B). It should be less than about 15% by weight, preferably
Should be no more than 12% by weight.

When an excessively large amount exceeding about 15% by weight is used, depending on the type of the solvent, the paint generally ignites and easily burns. In addition, the coating method, the drying step, and the like are also likely to be greatly restricted, and this is not preferable in terms of environmental pollution prevention measures.

In the present invention, of course, the organic solvent other than the organic solvent (B) may be used, for example, in the aqueous coating composition according to the present invention, that is, the drying property of paint, or the Above all, for leveling, film-forming properties and improvement in freeze stability, etc., it is possible to use them without difficulty within the limits of the amount of addition as described above. It does not prevent the combined use with an organic solvent other than the organic solvent (B). In addition, in the present invention, it is preferable to use many aprotic solvents when performing crosslinking by using a polyisocyanate compound.

Next, pigments will also be described. Originally, the water-based coating composition of the present invention can be used as a so-called clear coating in a form containing no pigment. Among them, various known and commonly used pigments can be used to impart so-called various functions, such as coloring, concealing property, hardness of a coating film, drying property, adhesiveness to a substrate, ultraviolet shielding and design property. However, it goes without saying that it can be used if necessary.

In such a case, only particularly typical examples of the pigment are exemplified, and titanium oxide, calcium carbonate, barium sulfate, mica, silica,
Various inorganic pigments represented by talc, clay, red iron oxide, iron black, zinc oxide, mapico yellow, carbon black or aluminum powder;

Alternatively, various organic pigments such as quinacridone red or phthalocyanine blue and the like, and further, these various pigments may be dispersed in an aqueous medium to form a commercially available, so-called aqueous pigment. And dispersed pigments.

The amount of the pigment used is not particularly limited, but is preferably used in an amount of about 120 parts by weight or less based on 100 parts by weight of the solid content of the aqueous resin dispersion (A). Is appropriate. In particular, if it is used in an excessively large amount exceeding about 120 parts by weight, the obtained coating film, especially, tends to have reduced smoothness and gloss, and thus the coating film appearance, It is not preferable because not only the visibility in visual observation is easily deteriorated, but also the stain resistance after outdoor exposure is apt to be greatly deteriorated. However, for specific purposes, such pigments and the like,
It does not prevent the gloss value from being appropriately selected and used to intentionally lower the gloss value.

In the present invention, a so-called crosslinked paint, in which a hydroxyl group is introduced into the aqueous resin dispersion (A) and combined with a polyisocyanate crosslinker, can be used to obtain a coating film, especially a weather resistant resin. This is also desirable from the viewpoint of improving water resistance, stain resistance, solvent resistance, and the like.

As described above, to introduce a hydroxyl group into the aqueous resin dispersion (A), it is most preferable to copolymerize a so-called hydroxyl group-containing polymerizable monomer as described above. Because it is simple, it could be recommended.

Here, only typical examples of the above-mentioned polyisocyanate compound used for preparing such a polyisocyanate-based cross-linking paint are given below, and examples thereof include tolylene diisocyanate and diphenylmethane diisocyanate. Various aromatic diisocyanates;

Various alicyclic diisocyanates such as hexamethylene diisocyanate or trimethylhexane diisocyanate; isophorone diisocyanate, methylcyclohexane-2,4 (or 2,6)
Various alicyclic isocyanates such as diisocyanate, 4,4'-methylenebis (cyclohexyl diisocyanate) or 1,3- (isocyanatomethyl) cyclohexane;

Alternatively, these various diisocyanates may be used in combination with various polyvalent compounds represented by ethylene glycol, polyether polyols (eg, polyethylene glycol, polypropylene glycol, polycaprolactone polyol), trimethylolethane, and trimethylolpropane. Alcohol,

Various low molecular weight polyester resins, various acrylic copolymers, adducts with water, etc. in the form of having a functional group which reacts with an isocyanate group; Body, etc., but among them, a particularly desirable example is

"Barnock D-750, D-800, D
N-950 or DN-901S "[the above are products of Dainippon Ink and Chemicals, Inc.] and the like. In addition, these various compounds may be used by emulsifying and dispersing them,

Alternatively, various water-soluble or water-dispersible polyisocyanate compounds, for example, “BAYHY
DUR LS-2980 or LS-2032 "(these are products of Bayer AG, Germany) or" Aquanate 100, 110, 200 or 210 "[the above are products of Nippon Polyurethane Industry Co., Ltd.], etc. However, various aqueous polyisocyanate compounds may also be used, and of course, the present invention is by no means limited to only these illustrative examples.

In the case of such a so-called polyisocyanate cross-linking system, the hydroxyl value of the solid content of the aqueous resin dispersion (A) is not limited to improve or improve various physical properties of a coating film to be obtained. Suitably between about 30 and about 120, and preferably between 50 and 100.

The polyisocyanate compound (C),
The mixing ratio with the aqueous resin dispersion (A) is NCO group /
It is appropriate to mix the OH groups in an equivalent ratio of about 0.5 to about 2, and preferably,
It is appropriate to mix them in the range of 0.8 to 1.3.

The aqueous coating composition according to the present invention, that is, a so-called coating composition, may be used in any known or conventional form within a range not departing from the object of the present invention or within a range not impairing the effects of the present invention. Various paint additives can be used.
If only a typical representative of such additives is exemplified, an antifoaming agent, a leveling agent, a thixotropic agent, a drying regulator, a dispersant, a thickener, an ultraviolet absorber, an antioxidant,
Preservatives, fungicides, antistatic agents, charge control agents, film-forming aids,
Plasticizers, crosslinking catalysts, freeze stabilizers, water repellents or wetting agents.

The aqueous coating composition of the present invention, that is, the coating of the present invention is not particularly limited in its use, base material, coating method, etc. Primarily in the field of civil engineering and construction, the interior and exterior of various alkaline inorganic cured structures, such as cement concrete and fiber reinforced cement boards, and their various members;

Various metal structures such as tanks, bridges or fences and their components; plastic members and wooden members;
Furthermore, it is also suitable as a top coat for repair, and also as a universal paint for home use, etc., and the aqueous coating composition according to the present invention is used, inter alia, at room temperature or forced drying. It is desirable.

The coating method at that time is also not limited, and if only typical ones among such coating methods are exemplified, a brush coating, a spray, a roller, a shower coat, and the like may be used. Alternatively, various known and common coating methods such as a curtain coat can be used and applied.

In addition, depending on the purpose of the coating at that time, any known and commonly used undercoating paint such as a rust preventive paint, a sealer, a sealing paint or a pattern paint may be applied to the undercoat. There are no restrictions. Furthermore, although the coating film thickness is also not limited, the aqueous coating composition according to the present invention,
In other words, it is desirable to apply the coating in the range of about 20 to about 150 micrometers or micron (μm) in order to develop the excellent properties of the coating of the coating of the present invention.

[0078]

EXAMPLES Hereinafter, the present invention will be described in more detail by reference examples, examples and comparative examples, but the present invention is in no way limited to only these illustrative examples. is not. In the following, all parts and percentages are by weight unless otherwise specified.

Reference Example 1 (Synthesis example 1 of aqueous resin dispersion)

In a reaction vessel equipped with a reflux condenser, a stirrer and a nitrogen inlet tube, ethylene glycol mono-n-
330 parts of butyl ether was charged, the temperature was raised to 110 ° C., and stirring was started.

Under a nitrogen stream at the same temperature, 33
0 parts, 395 parts of 2-ethylhexyl methacrylate,
240 parts of methyl methacrylate, 10 parts of acrylic acid and "NK ester M230G" [Shin Nakamura Chemical Co., Ltd.
Methoxylated polyethylene glycol (23 mol)
Methacrylate trade name], and a monomer mixture comprising 25 parts of

An initiator consisting of 20 parts of tert-butyl peroxy-2-ethylhexanoate and 10 parts of tert-butyl peroxybenzoate, and 30 parts of ethylene glycol mono-n-butyl ether were mixed with 3 parts
Over time, parallel additions were made.

Thereafter, 5 parts of tert-butyl peroxybenzoate was further added, and the temperature was maintained at the same temperature for 6 hours to complete the reaction. After cooling to 80 ° C., 13 parts of triethylamine was added, and 1,130 parts of ion-exchanged water was further added. The mixture was mixed and dispersed by a homogenizer.

The target aqueous resin dispersion thus obtained is a milky white liquid having a solid content of 40% and a
The viscosity at 5 ° C. (hereinafter abbreviated as viscosity) is 4.0 or 4.0.
00 mPa · sec. And the acid value of the solid content is 8,

The number average molecular weight in polystyrene conversion molecular weight measurement by gel permeation chromatography (GPC) was 11,000, the weight average molecular weight was 25,000, and the organic solvent content was 15%.
%. Hereinafter, this is abbreviated as DS-1.

Reference Example 2 (Synthesis 2 of aqueous resin dispersion)

First, as the monomer mixture,
200 parts of 2-ethylhexyl methacrylate, 350 parts of n-butyl methacrylate, 200 parts of cyclohexyl methacrylate, 200 parts of methyl methacrylate
Parts, 20 parts of methacrylic acid, "NK-ester M90
G "[trade name of methoxylated polyethylene glycol (9 mol) methacrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.]
And "Blemmer PME4000" [Methoxylated polyethylene glycol (90%, manufactured by NOF Corporation)
Mol) methacrylate].

By repeating the same operation as in Reference Example 1 except that the addition amount of triethylamine was changed to 23 parts, a milky white target aqueous resin dispersion was obtained. This aqueous resin dispersion has a solid content of 40% and a viscosity of 5,000 mPa · sec. The solid content acid value was 13, the number average molecular weight was 12,000, the weight average molecular weight was 27,000, and the organic solvent content was 16%. Hereinafter, this is abbreviated as DS-2.

Reference Example 3 (Synthesis of Aqueous Resin Dispersion 3)

First, 150 parts of ethylene glycol mono-i-propyl ether and 180 parts of ethylene glycol methyl ether acetate were used as the solvent for the initial preparation.

Further, as the monomer mixture,
300 parts of styrene, 40 parts of n-butyl methacrylate
0 parts, 100 parts of methyl methacrylate, 150 parts of β-hydroxyethyl methacrylate, 10 parts of acrylic acid
Department,

10 parts of "NK-ester M230G",
"NF-Visomer PME6E" [Daiichi Kogyo Pharmaceutical Co., Ltd.
Brand name of polyethylene glycol (6 mol) monomethacrylate manufactured by Toshiba Corporation]

By repeating the same operation as in Reference Example 1, a milky white desired aqueous resin dispersion was obtained here. This aqueous resin dispersion has a solid content of 40%
And the viscosity is 5,000 mPa · sec. The solid content acid value is 8, the solid content hydroxyl value is 70, the number average molecular weight is 11,000, and the weight average molecular weight is 27,
000, and the organic solvent content was 15%. Hereinafter, this is abbreviated as DS-3.

Reference Example 4 (Synthesis example 4 of aqueous resin dispersion)

In a reaction vessel equipped with a reflux condenser, a stirrer and a nitrogen inlet tube, 200 parts of ethylene glycol mono-i-propyl ether and 70 parts of N-methylpyrrolidone were charged, and heated to 110 ° C. Warm and start stirring.

Under a nitrogen stream, 505 parts of n-butyl methacrylate, 200 parts of i-butyl methacrylate, 90 parts of methyl methacrylate, 155 parts of β-hydroxyethyl methacrylate, 20 parts of acrylic acid, “NK
A monomer mixture consisting of 10 parts of "ester M230G" and 20 parts of "NF-Visomer PME6E";

60% of a mixture of 25 parts of tert-butylperoxy-2-ethylhexanoate and 30 parts of N-methylpyrrolidone, respectively, with the initiator were brought to the same temperature. The addition was carried out over 2 hours while maintaining.

Thereafter, the temperature was maintained at the same temperature for one hour, and while adding 1,170 parts of ion-exchanged water and 13 parts of triethylamine, the inside of the reaction vessel was cooled.
The temperature was lowered to 95 ° C. Further, the remainder of each of the monomer mixture and the initiator mixture was added at the same temperature over 1 hour, and 5 parts of tert-butylperoxy-2-ethylhexanoate was further added. Then, the same temperature was maintained for 2 hours.

After cooling to 80 ° C., 13 parts of triethylamine were added. This was treated with a homogenizer to obtain a milky white target aqueous resin dispersion. This aqueous resin dispersion has a solid content of 40% and a viscosity of 2,500 mPa · sec. In, the solid content acid value is 15, and the solid content hydroxyl value is 70,
The number average molecular weight is 13,000, the weight average molecular weight is 45,000, and the organic solvent content is 13
%. Hereinafter, this is abbreviated as DS-4.

Reference Example 5 (Preparation example 1 of control aqueous resin dispersion)

First, as the monomer mixture,
Modified to use 200 parts of 2-ethylhexyl methacrylate, 350 parts of n-butyl methacrylate, 200 parts of cyclohexyl methacrylate, 200 parts of methyl methacrylate and 50 parts of methacrylic acid,

By repeating the same operation as in Reference Example 1 except that the addition amount of triethylamine was changed to use 59 parts, a milky white target aqueous resin dispersion was obtained. . This aqueous resin dispersion has a solid content of 40% and a viscosity of 5,000 mPa.
-Sec. And the solid content acid value is 32, the number average molecular weight is 11,000, and the weight average molecular weight is 2
4,000, and the organic solvent content was 17%. Hereinafter, this is abbreviated as DS-5 '.

Reference Example 6 (Preparation example 2 of control aqueous resin dispersion)

First, 600 parts of ethylene glycol mono-n-butyl ether was charged into the same reaction vessel of Reference Example 1, and stirring was started while the temperature was raised to 110 ° C. Under a nitrogen stream at the same temperature, 300
Parts, 400 parts of 2-ethylhexyl methacrylate, 280 parts of methyl methacrylate

A monomer mixture consisting of 20 parts of acrylic acid and an initiator mixture consisting of 15 parts of tert-butylperoxy-2-ethylhexanoate and 10 parts of tert-butylperoxybenzoate; 30 parts of glycol mono-n-butyl ether were added in parallel over 4 hours.

Thereafter, 5 parts of tert-butyl peroxybenzoate was further added, and the mixture was maintained at the same temperature for 8 hours to complete the reaction. After cooling to 80 ° C, triethylamine 26
Was added, and 860 parts of ion-exchanged water was further added. The mixture was mixed and dispersed with a homogenizer.

The aqueous resin dispersion for control thus obtained was a translucent liquid having a solid content of 40% and a viscosity of 6,000 m
Pa · sec. , The solid content acid value was 13, the number average molecular weight was 11,000, the weight average molecular weight was 23,000, and the organic solvent content was 27% as measured by GPC. Hereinafter, this is abbreviated as DS-6 '.

Reference Example 7 (Preparation example 3 of control aqueous resin dispersion)

First, as the monomer mixture,
400 parts of ethyl acrylate, 550 parts of methyl methacrylate, 20 parts of methacrylic acid, 15 parts of "NK-ester M90G" and "Blemmer PME400
0 ", and the same operation as in Reference Example 1 was repeated except that the addition amount of triethylamine was changed to 23 parts. A control aqueous resin dispersion was obtained.

The aqueous resin dispersion for control thus obtained had a solid content of 40% and a viscosity of 6,000 mPa.s.
-Sec. , The acid content of the solid content is 13, the number average molecular weight is 12,000, and the weight average molecular weight is 2
6,000, and the organic solvent content was 16%. Hereinafter, this is abbreviated as DS-7 '.

Reference Example 8 (Preparation example 4 of control aqueous resin dispersion)

First, 300 parts of styrene and 350 parts of 2-ethylhexyl methacrylate were used as the monomer mixture.
Parts, 280 parts of methyl methacrylate, 50 parts of “NK ester M230G” and “Blemmer PME400
By repeating the same operation as in Reference Example 1 except that 20 parts of "0" were used, a milky-white aqueous resin dispersion for control was obtained.

The aqueous resin dispersion for reference thus obtained has a solid content of 40% and a viscosity of 3,000 mP.
a.sec. , The acid value of the solid content is 0, the number average molecular weight is 12,000, and the weight average molecular weight is 2
It was 8,000, and the organic solvent content was 15%. Hereinafter, this is abbreviated as DS-8 '.

Examples 1 to 8 and Comparative Examples 1 to 10 Each of the aqueous resin dispersions obtained in Reference Examples 1 to 8 was made into a paint in the following manner. As a comparative product, a solvent-based paint and an acrylic-based emulsion gloss paint were applied on various substrates, and then a test for evaluating various properties of the coating film thus obtained was performed.

The results are collectively shown in Tables 1, 2 and 3, wherein Table 1 shows the properties of the non-crosslinked paint and various physical properties of the coating, and the results are shown in Table 1 when dried at room temperature. And Table 2 shows the properties of the crosslinked paint and various physical properties of the coating film, which were obtained at room temperature drying, and Table 3 shows the crosslinked paint and It shows the properties of the paint and the physical properties of the coating film of both systems, that is, the non-crosslinked system, and the case of forced drying.

Formulation example 1 of non-crosslinked water-based paint

Aqueous resin dispersion (solid content: 40%) 125 parts “Taipek R930” [trade name of titanium oxide manufactured by Ishihara Sangyo Co., Ltd.] 82 parts “Nopco 8034” [defoaming manufactured by San Nopco Co., Ltd.] Trade name of the agent] 0.2 parts ion exchange water 0-10 parts

[0118] Sand mill dispersion, 1 hour

(Let down prescription)

Aqueous resin dispersion 125 parts Deionized water 0 to 20 parts

Paint solids 52-54% PWC 45% Paint viscosity Adjusted to 70-76 KU (Stomer viscometer) with ion-exchanged water in the mixing ratio table.

Resins used DS1 and 2 and 5 ', 6', 7 'and 8'

Formulation Example 2 of non-crosslinked, solvent-based paint

Acrylic A181X (acrylic-styrene resin for lacquer, manufactured by Dainippon Ink and Chemicals, Incorporated; a solid content of 45% in the form of xylene as a solvent) was used as described above. 1 (except that
Xylene is used only as the diluting solvent. ), A coating material having a solid content of 40% and a PWC of 45% was prepared.

Formulation example 3 of water-based paint of crosslinking type

Aqueous resin dispersion (solid content = 40%) 125 parts “Taipec R930” 100 parts “Nopco 8034” 0.2 parts Ion exchange water 10 parts {Sand mill dispersion, 1 hour} ───────────

(Let down prescription)

Aqueous resin dispersion 125 parts Ion-exchanged water 10 to 30 parts {hardening agent blending} "Aquanate 210" / water = 1 / 1 (parts by weight) 50-74 parts

Paint solids 52-55% PWC 42-44% NCO / OH equivalent ratio 0.8-1.2 Paint viscosity Adjusted to 70-76 KU with ion-exchanged water in the mixing ratio table.

Resin used DS3 and 4

<< Note >>"Aquanate210": trade name of water-dispersible polyisocyanate compound manufactured by Nippon Polyurethane Industry Co., Ltd .; NCO content = 17%

Formulation Example 4 for Crosslinking Solvent-Based Paint

“Acrydic A801” [trade name of acrylic polyol manufactured by Dainippon Ink and Chemicals, Inc .; solid content = 50%, solid content hydroxyl value = 100, toluene / n-butyl acetate solvent] and “Acrylic A801” Burnock DN-9
50 "(trade name of polyisocyanate compound, manufactured by Dojo Co .; solid content = 75%, ethyl acetate solvent, NCO = 12
%], The solid content is 44%, and P
A coating material having a WC of 43% and an NCO / OH equivalent ratio of 1 (the diluent solvent was n-butyl acetate) was prepared.

Formulation Example 5 of Emulsion Paint

A Bon Coat EC889 (Acrylic Styrene emulsion for gloss paint (50% solid content), manufactured by Dainippon Ink and Chemicals, Inc.) was used.
A gloss paint was prepared according to the following formulation.

Ion-exchanged water 42 parts 10% aqueous solution of sodium tripolyphosphate 1.6 parts “Demol NL” [trade name of a dispersant manufactured by Kao Corporation] 1.2 parts Ethylene glycol 5.2 parts “Best side FX” [Product name of preservative manufactured by Dainippon Ink and Chemicals, Inc.] 0.3 parts "SN Deformer 373" [brand name of antifoaming agent manufactured by San Nopco Co., Ltd.] 0.2 parts Taipaque R930 ”81 copies

分散 Dispersion dispersion, 2 hours────────────

“Boncoat EC889” 200 parts “Texanol” (trade name of a film-forming aid manufactured by Eastman Kodak Company, USA) 15 parts 3% “Serosize QP4400H” (Union Carbide, USA) Hydroxyethylcellulose is a trade name and is used as a thickener.) Aqueous solution 5 parts 28% ammonia water 0.3 parts 15% “UH438” [trade name of a thickener manufactured by Asahi Denka Co., Ltd.] 6 parts "SN Deformer 373" 0.7 parts Ion exchange water 22 parts

───────────── Stirring ────────────

Paint solids 48% PWC 45% Paint viscosity 73 KU

(Application Test Conditions)

Base material: Cement / asbestos board [product of Nozawa Slate Co., Ltd., 150 × 70 × 3 m
m. ]

Glass plate [a product of Japan Test Panel Co., Ltd., having the same size as the above case. ]

Aluminum plate (of the same size as above)

Coating: The cement / asbestos plate was coated twice with a brush so that the dry film thickness was 80 μm.

The aluminum plate was coated with an applicator so that the dry film thickness was 80 μm.

Drying at normal temperature: After coating, the coating was left to dry for one week under conditions of a temperature of 20 ° C. and a relative humidity of 65%.

Forced drying: 80 ° C. after coating
For 10 minutes, and then left for one week under the same conditions as in the case of the normal temperature drying described above.

Flash point measurement: Measurement was carried out using a creepland open type flash point measuring machine.

Mitsuzawa: 3 mils on a glass plate
After coating with an applicator and drying under predetermined conditions, a so-called gloss value of a 20-degree specular gloss and a 60-degree specular gloss was measured with a reflection gloss meter, respectively. .

-Actual exposure contamination resistance: 1-3 Takasago, Takaishi-shi, Osaka
In the Dainippon Ink and Chemicals, Inc. Sakai Plant,
After the exposure for 6 months, the appearance of the cement-asbestos board and the coated board made of the aluminum board were determined by visual inspection.

Accelerated weather resistance: A cement / asbestos-coated plate and an aluminum-coated plate were subjected to a test for 1,000 hours with a sunshine weather meter, respectively. It was expressed as gross retention using the ratio to the value.

Freezing and thawing resistance: A cement-asbestos-coated plate is placed horizontally on a plastic tray, and water is poured. The coated plate is completely immersed therein.
4 hours → 4 hours at 40 ° C., and this was repeated for 20 cycles, and the change in the state of the coating film was visually determined.

Water resistance: A cement / asbestos-coated plate was immersed in tap water at 20 ° C. for 30 days, and the state change of the coating film was visually judged.

Alkali resistance: A cement / asbestos-coated plate was immersed in a 2% NaOH / saturated Ca (OH) ₂ aqueous solution at 20 ° C. for 30 days, and the state change of the coating film was visually determined.

Solvent resistance: The coating film on the glass coated plate is
Rubbing was performed 20 times with gauze impregnated with xylene, and the change in the state of the coating film was visually determined.

[0157]

[Table 1]

<< Note >>"Accelerated weathering resistance" is an abbreviation of "accelerated weathering resistance (GR,%)", which is a value of the gross retention as described above, expressed as a percentage. Moreover,
The values in parentheses are for the case of an aluminum coated plate using an aluminum plate as a base material, while those without the parentheses are for the case of a cement / asbestos coated plate.

Evaluation criteria: ○: good Δ: slightly poor ×: poor

[0160]

[Table 2]

[0161]

[Table 3]

<< Note >> The numerical values in parentheses are for aluminum-coated plates.

[0163]

[Table 4]

[0164]

[Table 5]

<< Note >> The numerical values in parentheses are for aluminum coated plates.

[0166]

[Table 6]

[0167]

As is clear from the results of Tables 1, 2 and 3, the water-based coating composition according to the present invention is
Compared to solvent-based paints, or even better than this, it has a coating film physical properties and coating appearance unprecedented in the past, in addition,
Since the organic solvent content is low, there is little risk of ignition and combustion, and further, it is extremely practical from the viewpoint of environmental pollution prevention measures and resource saving.

As described above, the present invention provides an aqueous coating composition having extremely high practicality, and at the same time, provides such a valuable aqueous coating composition. It's easy to know what is important.

Claims (4)

[Claims] 1. Non-functional (meth) acrylates having a hydrocarbon group having 4 to 12 carbon atoms (a-1)
Or a non-functional (meth) acrylic acid ester and an aromatic vinyl monomer (a-2), a monofunctional unsaturated monomer having a polyethylene glycol group (b), and α , Β-ethylenically unsaturated carboxylic acid (c)
And the monomer (b) obtained by using the above-mentioned monomer (a-1) or (a-2) in a total amount of 65% by weight or more in the total polymerizable unsaturated monomer. And the monomer (c) is in the range of 3 to 6% by weight, and the ratio of the monomer (b) / the monomer (c) is 1 to 5 by weight.
An aqueous resin dispersion (A) of a vinyl polymer having self-water dispersibility within a range of from about 130 to about 130.degree.
And an organic solvent (B) having a solubility of water of 100 or more at 20 ° C. as an essential component in the range of about 220 ° C. to about 220 ° C. About 20% by weight based on 100 parts by weight of the solid content of A)
An aqueous coating composition containing the above, and wherein the total amount of organic solvents in the obtained aqueous coating composition is about 15% by weight or less. 2. Non-functional (meth) acrylic esters having a hydrocarbon group having 4 to 12 carbon atoms (a-1)
Or the non-functional (meth) acrylic acid ester and the aromatic vinyl monomer (a-2), the monofunctional unsaturated monomer having a polyethylene glycol group (b), and α , Β-ethylenically unsaturated carboxylic acid (c)
And the above-mentioned monomer (b) obtained by using the above-mentioned monomer (a-1) or (a-2) in a total amount of 65% by weight or more in the total polymerizable unsaturated monomer. And the above-mentioned monomer (c) is in the range of 3 to 6% by weight, and the ratio by weight of the above-mentioned monomer (b) / the above-mentioned monomer (c) is 1 to 5
Aqueous resin dispersion (A) having self-water dispersibility within a range, and a boiling point under normal pressure of about 130 to about 220 ° C., and water solubility at 20 ° C. of 100 or more. The organic solvent (B) and the curing agent (C) are essential components, and the organic solvent (B) is added in an amount of about 20 parts by weight based on 100 parts by weight of the solid content of the aqueous resin dispersion (A). %
An aqueous coating composition containing the above, and wherein the total amount of organic solvents in the obtained aqueous coating composition is about 15% by weight or less. 3. The aqueous resin dispersion (A) has a number average molecular weight of about 8, as a polystyrene-equivalent molecular weight determined by gel permeation chromatography.
000 to about 20,000, the weight average molecular weight is about 15,000 to about 50,000, and the acid value in terms of solid content is about 3 to about 18 mgK.
3. The composition according to claim 1, which is in the range of OH / g.
A composition according to claim 1. 4. The composition according to claim 1, wherein the aqueous resin dispersion (A) has a number average molecular weight of about 8, as a polystyrene equivalent molecular weight by gel permeation chromatography. The water-based resin dispersion (A) has a hydroxyl value in terms of solid content in the range of 000 to about 20,000 and the weight average molecular weight in the range of about 15,000 to about 50,000. Is in the range of about 30 to about 120 mgKOH / g, and the curing agent (C) is a polyisocyanate compound, and the polyisocyanate compound is based on the aqueous resin dispersion (A). And NCO group / OH
A water-based coating composition characterized in that it is blended in a range of about 0.5 to about 2 at a basic equivalent ratio.