JP2002047450A - Water-based coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a water-based coating composition which has a volatile organic solvent content of less than 1 wt.% and is excellent in the brush applicability on brush coating and blushing. SOLUTION: This water-based coating composition having a volatile organic compound content of less than 1 wt.% and containing a resin emulsion and a thickener, is characterized in that the thickener consists of a Newtonian viscosity imparting agent and a pseudo-plastic viscosity imparting agent and is contained in an amount as a solid content of 0.3-3.0 wt.% relative to the coating composition. For example, a weight ratio of the solid content of the Newtonian viscosity imparting agent to that of the pseudo-plastic viscosity imparting agent is 3/1 to 12/1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based coating composition, and more particularly to a water-based coating composition excellent in workability of coating.

[0002]

2. Description of the Related Art A water-based paint used for indoor coating usually contains a volatile organic compound called VOC as an antifreezing agent or a film-forming aid. However, recent environmental problems, unpleasant odor and sick house syndrome have occurred. From the viewpoint of the effects on the human body such as chemical sensitivity, water-based paints have been commercialized that minimize VOCs contained in the paint itself and VOCs released from the resulting coating film as much as possible.

A typical example of such an aqueous paint is an aqueous paint containing a resin emulsion as a main component. However, such a paint has a low viscosity, so that the coating workability is poor, and more specifically, there is a problem that the brush slip is strong at the time of brush application and the fogging is poor. Therefore, in order to give an appropriate viscosity at the time of brush application, it has been attempted to add a thickener that imparts Newtonian viscosity.However, in order to sufficiently obtain the viscosity at the time of brush application, it is necessary to add a thickener to the paint. There is a possibility that the amount of the paint may be increased and the sagging property at the time of coating may be deteriorated, the performance of the obtained coating film may be deteriorated, or the viscosity of the paint itself may be increased, thereby making it difficult to handle. In particular, in a water-based paint substantially free of volatile organic compounds, which has recently been developed and has a content of volatile organic compounds of less than 1% by weight,
This tendency is remarkable, and a practical problem has occurred.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an aqueous coating composition containing less than 1% by weight of a volatile organic solvent excellent in brush slipping and fogging during brush coating. Aim.

[0005]

According to the present invention, there is provided an aqueous coating composition containing a resin emulsion and a thickener, wherein the content of a volatile organic solvent is less than 1% by weight. And a pseudoplastic viscosity imparting agent, and the content thereof is 0.3 wt.
It is an aqueous coating composition characterized in that it is about 3.0% by weight. For example, the solid content weight ratio of the Newtonian viscosity-imparting agent to the pseudoplastic viscosity-imparting agent is 3/1 to 12/1. Here, the Newtonian viscosity-imparting agent is preferably a nonionic polyurethane resin, and the pseudoplastic viscosity-imparting agent is preferably a cellulose derivative.

The emulsion resin is an acrylic resin emulsion, and the content of the acrylic resin emulsion in the coating composition is preferably 3% by weight or more in terms of resin solid content, and its Tg is -60 to -10. ° C, number average molecular weight is 5000-200000 and acid value is 15-
Preferably it is 50.

Further, the aqueous coating composition of the present invention contains a nonionic surfactant, and the content thereof is 0.2 to 5%.
% By weight, and its HLB is 12.5 to
It is preferably 18.5.

Further, the aqueous coating composition of the present invention contains a pigment, and the content of the pigment is 25% by volume of the pigment.
It is preferable that it is above.

Further, the aqueous coating composition of the present invention has a viscosity of 7 in a Stormer viscometer at 25 ° C.
It is preferable that the viscosity measured by a rotary viscometer at ⁰ KU is 0.5 poise or more at a shear rate of 10 ⁴ sec ^-1 .

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The volatile organic compound (hereinafter abbreviated as VOC) in the present invention means one having a boiling point of 250 ° C. or less.

The aqueous coating composition of the present invention comprises a resin emulsion and a thickener, wherein the content of a volatile organic solvent is less than 1% by weight. Agent and a pseudoplastic viscosity-imparting agent, and the content thereof is 0.3% in solid content in the coating composition.
To 3.0% by weight.

One Newtonian viscosity-imparting agent constituting the thickener contained in the water-based coating composition of the present invention facilitates brushing of the coating and improves fogging during coating. Specifically, a nonionic polymer type can be used. Commercially available products such as this include polyurethane resin Adecanol UH series (manufactured by Asahi Denka Co., Ltd.) and BERMODOL PU.
R series (Akzo Nobel), Primal RM-
Examples include 2020NPR (manufactured by Rohm and Haas Japan) and OPTIFLO series (manufactured by Nissan Sudohemie Catalysts), which is a non-urethane resin. Among them, a nonionic polyurethane resin is preferred from the viewpoint of sagging during coating.

The other pseudoplastic viscosity-imparting agent constituting the thickener suppresses sagging after brush application. Specific examples include cellulose derivatives, higher fatty acid amides, modified polysaccharides, modified acrylic copolymers, and the like. Examples of commercially available products such as these include the BERMOCOLL series (manufactured by Akzo Nobel) in the above hydroxycellulose derivatives,
Chixol W-300 (manufactured by Kyoeisha Chemical Co., Ltd.) for higher fatty acid amides and BENAQUA for modified polysaccharides
1000 (manufactured by Elementis Japan Co., Ltd.), and RHEOLATE430 (manufactured by Elementis Japan Co., Ltd.) for modified acrylic copolymer, Primal DR series,
Primal TT-615 (both manufactured by Rohm and Haas Japan) can be exemplified. Among these, a cellulose derivative is preferable, and a hydroxycellulose derivative is more preferable, from the viewpoints of film repellency and tonality.

The solid content weight ratio of the Newtonian viscosity-imparting agent and the pseudoplastic viscosity-imparting agent constituting the thickener contained in the aqueous coating composition of the present invention may be 3/1 to 12/1. More preferably, it is 6/1 to 9/1. If the solid content ratio is less than 3/1, the coating workability may be reduced, and if it exceeds 12/1, sagging may occur during coating.

Here, the solids content of the above-mentioned thickener is 0.3 to 3.0% by weight based on 100 parts by weight of the coating composition.
From the viewpoint of workability and sagging during painting, 0.4
Preferably it is ~ 2.0% by weight. When the content is less than 0.3% by weight, the coating workability is not improved, and when the content is more than 3.0% by weight, the viscosity of the coating material itself becomes high, so that the handleability and color mixing stability are increased. Or the water resistance of the resulting coating film decreases.

[0016] The aqueous coating composition of the present invention contains a resin emulsion. The resin emulsion is not particularly limited, and examples thereof include acrylic resin emulsions, polyester resin emulsions, urethane resin emulsions, and other resin emulsions well-known by those skilled in the art.From the viewpoints of weather resistance and water resistance, It is preferably an acrylic resin emulsion.

When the resin emulsion is an acrylic resin emulsion, its Tg is from -60 to -10 ° C, preferably from -45 to -20 ° C. The number average molecular weight is 5,000 to 20,000, and 5,000 to 5,000.
It is preferably 15,000. Further, the acid value is 15
-50, preferably 25-45.

Further, the acrylic resin emulsion is
It may have a multilayer structure called a so-called core / shell structure. In the case of exhibiting a multilayer structure, the proportion of the core portion may be 80% by weight or less in the emulsion particles. The shell polymer has a Tg of −60 to −10 ° C., a number average molecular weight of 5,000 to 20,000, an acid value of 15 to 50, and the core polymer has a Tg of −60 to −20 ° C., and a number average molecular weight of 5,000 to 5,000. 500,000 and an acid value of 0 to 50.

The acrylic resin emulsion has a Tg of-
When the temperature exceeds 10 ° C, the surface tends to crack after drying when the coating film thickness is large, and when the temperature is lower than -60 ° C,
It is difficult to synthesize with general-purpose raw materials.

When the acrylic resin emulsion has a number average molecular weight of more than 20,000, cracks tend to be formed on the coating film surface after drying, and when the number average molecular weight is less than 5,000,
Since a large amount of a chain transfer agent is required at the time of resin synthesis, a mercaptan odor remains in the acrylic resin emulsion, which is not preferable.

The acrylic resin emulsion has an acid value of 5
If it exceeds 0, the water resistance of the coating film deteriorates, and if it is less than 15, the adhesion of the coating film decreases, which is not preferable.

In the present invention, Tg and acid value are as follows:
By calculation from the type and amount of monomer used in the production,
You can ask. The number average molecular weight can be determined by measuring the obtained emulsion resin using gel permeation chromatography (GPC).

The average particle size of the acrylic resin emulsion is not particularly limited, but is preferably 150 to 200 nm from the viewpoint of touch-up properties.

As a method for obtaining such an acrylic resin emulsion, a method in which an ethylenically unsaturated monomer is emulsion-polymerized in water, or a method in which an ethylenically unsaturated monomer is polymerized in an organic solvent, followed by desolvation and emulsification. Examples of the method include a method in which the process is simple, and a method obtained by emulsion polymerization in water that does not require consideration of the residual organic solvent is preferable. Specifically, in water at 40 to 100 ° C., ethylenic acid is preferably used. A method in which an unsaturated monomer is reacted for 2 to 10 hours using 0.1 to 5% by weight of a radical polymerization initiator and an appropriate amount of a chain transfer agent in the presence of 0.2 to 10% by weight of an emulsifier. be able to.

The above ethylenically unsaturated monomers include:
For example, acrylic acid or methacrylic acid and its alkyl esters, for example, methyl ester, ethyl ester, isobutyl ester, s-butyl ester, t-
Butyl esters, 2-ethylhexyl esters, lauryl esters, etc .; vinyl compounds, for example, styrene, methylstyrene, etc .; carboxylic acids, for example, acrylic acid, methacrylic acid, maleic acid, itaconic acid, etc .; hydroxyalkyl esters of acrylic acid or methacrylic acid , For example, hydroxyethyl ester, hydroxypropyl ester, hydroxybutyl ester and the like; nitriles,
Examples thereof include (meth) acrylonitrile and the like; amides such as (meth) acrylamide, N-methylolacrylamide, N, N-dimethylacrylamide and N-isopropylacrylamide. Two or more of these ethylenically unsaturated monomers may be used.

Examples of the polymerization initiator include persulfates such as ammonium persulfate and potassium persulfate; peroxides such as t-butyl hydroperoxide and hydrogen peroxide; redox initiators such as sulfurous acid Combinations of reducing agents such as sodium hydrogen, sodium sulfite, ascorbic acid, Rongalite and oxidizing agents such as the above initiators; azo compounds such as 4,4'-azobis-4-cyanovaleric acid; it can.

As the emulsifier, an anionic emulsifier,
For example, dodecylbenzene sulfonate, lauryl sulfate, alkyl diphenyl ether disulfonate, dialkyl sulfosuccinate, polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene polycyclic phenyl ether sulfate, polyoxyethylene alkyl ether sulfate, etc. , Nonionic emulsifiers such as polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene polycyclic phenyl ether, polyoxyethylene sorbitan fatty acid ester, etc .; anionic or nonionic and having a radical polymerizable group A so-called reactive emulsifier, for example, Aqualon HS-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., polyoxyethylene alkylpropenyl phenyl ether sulfate), Aqualon RN-2 (Daiichi Kogyo Seiyaku Co., Ltd., polyoxyethylene alkylpropenyl phenyl ether), Eleminol JS-2 (Sanyo Chemical Industry Co., Ltd., sodium alkyl allyl sulfosuccinate), Latemul S-180A (Kao Co., Ltd., sulfosuccinic acid type reactive activity) Agent (oleyl ammonium salt)), and Antox MS-60 (manufactured by Nippon Emulsifier Co., Ltd., bis (polyoxyethylene polycyclic phenyl ether) methacrylate sulfate).

Examples of the chain transfer agent include lauryl mercaptan, t-dodecyl mercaptan, octyl mercaptan, 2-ethylhexyl thioglycolate,
Examples thereof include 2-methyl-5-t-butylthiophenol.

The acrylic resin emulsion having a multilayer structure can be obtained by a conventional two-stage polymerization method based on the above method.

A neutralizing agent may be used to adjust the pH of the obtained acrylic resin emulsion, for example, ammonia, N, N-dimethylaminoethanol,
Examples thereof include amines such as 2-amino-2-methyl-1-propanol and hydroxides such as sodium hydroxide and potassium hydroxide. From the viewpoint of VOC and obtained coating film performance, 2-amino- Preferably, it is 2-methyl-1-propanol. Further, the neutralization rate by such a neutralizing agent is preferably 10% or less from the viewpoint of VOC.

When the aqueous coating composition of the present invention contains the above acrylic resin emulsion, the resin solid content in the coating resin solid content is 3% by weight or more, and is 8 to 35%.
% By weight. When the content is less than 3% by weight, a coating film may not be formed.

[0032] The aqueous coating composition of the present invention may further contain a nonionic surfactant. By containing the nonionic surfactant, the paint can be prevented from freezing. Specific examples of the nonionic surfactant include polyoxyalkylene-based surfactants. Such polyoxyalkylene-based nonionic surfactant HLB (hydrophile-lipophile)
e balance) is preferably 12.5 to 18.5. When the HLB is more than 18.5, the hydrophilicity is too high, and the adsorptivity to the hydrophobic portion on the particle surface is reduced, so that the freeze stabilizing function is not exhibited. The hydration ability of the group decreases, and the paint stability during freezing cannot be ensured.

Examples of the polyoxyalkylene-based nonionic surfactant include polyoxyethylene nonyl phenyl ether, polyoxyethylene alkyl phenyl ether such as polyoxyethylene polyoxyethylene octyl phenyl ether, polyoxyethylene lauryl ether, and the like. Polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene alkyl ether such as polyoxyethylene oleyl ether, polycyclic phenyl is polyoxypolycyclic phenyl ether such as distyrenated phenyl, fatty acid is lauric acid,
Examples thereof include polyoxyethylene sorbitan fatty acid esters such as stearic acid and oleic acid. The nonionic surfactant has a high boiling point and does not hit the VOC component. The HLB in the present invention is obtained by the Griffin formula.

When the aqueous coating composition of the present invention contains the above nonionic surfactant, its content in the coating resin solids is preferably from 0.025 to 1.25% by weight, and more preferably from 0.05 to 25% by weight. More preferably, it is 0.5% by weight. If the content exceeds 1.25% by weight, the water resistance of the resulting coating film may be reduced.
If the content is less than 25% by weight, the coating composition may coagulate during freezing and may not be redispersed after dissolution.

The aqueous coating composition of the present invention can contain a pigment from the viewpoint of improving the appearance. Such pigments are not particularly limited, and include, for example, inorganic pigments such as titanium dioxide and carbon black, phthalocyanine, benzimidazolone, isoindolinone, azo, anthraquinone, quinophthalone, and anthrapyridinine. And organic pigments such as quinacridone, toluidine, pyrathron, and perylene pigments.

When the aqueous coating composition of the present invention contains the above pigment, its content in the coating resin solid content of the coating composition is 25% or more in terms of pigment volume concentration (PVC), and is 45% or more.
It is preferably about 70%. When the pigment volume concentration is 2
If it is less than 5%, the surface tackiness of the coating film increases,
Coating quality may be poor and impractical.

Further, in addition to the above-mentioned components, the aqueous coating composition of the present invention may further comprise a pigment dispersant, an extender, a surface conditioner, a defoamer, an ultraviolet absorber, an antioxidant, and a preservative. And other components well known by those skilled in the art, such as fungicides, anti-algal agents, and the like.

The aqueous coating composition of the present invention has a temperature of 25 ° C.
When the viscosity by the Stormer viscometer in the above was 70 KU, the viscosity by the rotary viscometer was 10 ⁴ seconds.
^-1 is preferably 0.5 poise or more, from the viewpoint of workability at the time of coating, from 0.5 to 2.0 poise.
is more preferable, and 0.5 to 1.5 po
More preferably, it is "is". When the viscosity by the above rotary viscometer is less than 0.5 poise, it is easy to slip at the time of brush application, there is a possibility that sufficient fogging may not be obtained, or when it exceeds 1.5 poise, at the time of brush application It is heavy, and coating workability may be reduced. Here, the rotational viscometer is not particularly limited, and is well known by those skilled in the art, such as a rotational viscometer using a rotor such as a cone plate of a type that matches the viscosity range of the paint to be measured. Things can be mentioned.

Further, the water-based coating composition of the present invention has a low VOC content in the coating composition from the viewpoint of environmental pollution and influence on the human body.
Is less than 1% by weight, and preferably less than 0.1% by weight. The content of VOC in the coating composition is
It can be determined by measuring by a method well known to those skilled in the art, such as a mini-chamber method by the Japan Paint Manufacturers Association, which is a method of measuring VOC released from the coating film, or by calculating from the coating composition.

The aqueous coating composition of the present invention can be produced by mixing and uniformly dispersing the above-mentioned raw materials by a method well known to those skilled in the art. When the above nonionic surfactant is contained, it is preferable to add it at the time of final coating.

The aqueous coating composition of the present invention thus obtained is diluted with water according to the purpose, and can be applied by a method well known to those skilled in the art. For coating, it is also possible to perform recoating on an object to be coated.

The water-based coating composition of the present invention is generally applied to various objects by brushing.
In addition, it may be applied by a method generally known by those skilled in the art, for example, spray coating, roller coating, roll coater, curtain flow coating, spray coating, knife edge coating, dip coating, and the like. After application, the coating can be obtained at room temperature. The amount of coating, the thickness of the coating, and the drying time can be arbitrarily set according to the type of the coating material and the object to be coated.

[0043]

EXAMPLES Production Example 1 Production of acrylic resin emulsion 1
Concrete dropping funnel, a thermometer, a nitrogen inlet tube, reflux condenser and equipped with a stirrer 5-necked separable flask of ion-exchanged water 2
In a nitrogen atmosphere, the temperature was raised to 80 ° C. After adding 10 parts by weight of laurimercaptan to a monomer mixture comprising 318 parts by weight of styrene, 40 parts by weight of methyl methacrylate, 581 parts by weight of 2-ethylhexyl acrylate and 61 parts by weight of methacrylic acid, the mixture was added to Perex SS- H (sodium alkyl diphenyl ether disulfonate manufactured by Kao Corporation) in 20 parts by weight of deionized water 6
The mixture was added to an emulsifier aqueous solution dissolved in 00 parts by weight and emulsified using a mixer. A 1/20 amount of the pre-emulsion thus obtained was charged into a flask and stirred for 10 minutes, and then an initiator aqueous solution in which 0.75 parts by weight of ammonium persulfate was dissolved in 10 parts by weight of ion-exchanged water was added to carry out polymerization. The reaction was started. Then, after stirring for 10 minutes,
2.25 parts by weight of ammonium persulfate was added to ion-exchanged water 15
The aqueous initiator solution dissolved in 0 parts by weight and the remaining amount of the monomer pre-emulsion were simultaneously dropped from separate dropping funnels. The former started dropping evenly over 200 minutes and the latter started dropping evenly over 180 minutes. After the completion of the dropwise addition, the reaction was continued at the same temperature for another 120 minutes. After cooling, the mixture was neutralized with aqueous ammonia corresponding to 10 mol% of the methacrylic acid used. The neutralized product was filtered through a wire mesh of 400 mesh to obtain a resin solid content of 50%.
Acrylic resin emulsion 1 was obtained by weight. Table 1 shows the number average molecular weight of the obtained acrylic resin emulsion obtained by measurement by GPC (gel permeation chromatography), and the Tg and resin solid content acid value obtained by calculation from the compounding amount.

Production Example 2 Preparation of acrylic resin emulsion 2
Were charged 200 parts by weight of deionized water to the same apparatus as in Production Example 1, it was heated to 80 ° C. under a nitrogen atmosphere, except in accordance with the formulation shown in Table 1, resin solid in the same manner as in Production Example 1 Min 5
An acrylic resin emulsion 2 of 0% by weight was obtained. In addition,
Table 1 shows the number average molecular weight of the obtained acrylic resin emulsion obtained by measurement by GPC (gel permeation chromatography), the Tg and the acid value of the resin solid content obtained by calculation from the compounding amount.

Production Example 3 Acrylic resin having a multilayer structure
Emulsion 3 200 parts by weight of deionized water were charged into the same apparatus as in Production Example 1, and the temperature was raised to 80 ° C. Perex SS-H (Kao Corporation,
Sodium alkyl diphenyl ether disulfonate)
10 parts by weight and Newcol 504 (manufactured by Nippon Emulsifier Co., Ltd., polyoxyethylene nonylphenyl ether, HLB = 1
6.0) Two emulsifier aqueous solutions prepared by dissolving 10 parts by weight in 300 parts by weight of ion-exchanged water were prepared, and the first and second-stage monomers and the chain transfer agent having the formulations shown in Table 1 were respectively prepared. The mixture was added and stirred to prepare a pre-emulsion. 1/10 amount of the obtained first stage pre-emulsion was charged into a flask, stirred for 10 minutes, and then an initiator aqueous solution in which 0.75 parts by weight of ammonium persulfate was dissolved in 10 parts of ion-exchanged water was added to carry out polymerization. Was started. After stirring for 10 minutes, an initiator aqueous solution obtained by dissolving 2.25 parts by weight of ammonium persulfate in 150 parts by weight of ion-exchanged water and the remaining amount of the pre-emulsion of the first-stage monomer were simultaneously dropped from separate dropping funnels. . The former was dropped evenly over 200 minutes and the latter over 80 minutes. Ten minutes after the end of the latter dropping, the pre-emulsion of the second stage monomer was added dropwise over 90 minutes. After all the drops were completed, the reaction was continued at the same temperature for another 120 minutes. After cooling, the mixture was neutralized with aqueous ammonia corresponding to 10 mol% based on the methacrylic acid used. This was filtered through a 400 mesh wire net to obtain an acrylic resin emulsion 3 having a resin solid content of 50% by weight. Note that T between the first stage and the second stage
Table 1 shows the acid value of g and the resin solid content, and the number average molecular weight of the obtained acrylic resin emulsion.

[0046]

[Table 1]

Production Example 4 Preparation of Pigment Dispersion Paste 120 parts by weight of ion-exchanged water, 120 parts by weight of Daicel SP600N (hydroxyethylcellulose-based thickener, 2.5% by weight aqueous solution manufactured by Daicel Chemical Industries, Ltd.), and Nopco Spars 44C (manufactured by San Nopco) 12 parts by weight of a polycarboxylic acid-based pigment dispersant, 2 parts by weight of SN-154 (an antifoaming agent manufactured by San Nopco), 266 parts by weight of calcium carbonate (a first-class product manufactured by Kishida Chemical) and titanium CR-95 (Ishihara Sangyo Co., Ltd.) 200 parts by weight of titanium dioxide) and dispersed in a sand grinder mill for 0.5 hour to obtain a solid content of 50% by weight.
A pigment-dispersed paste having a dispersed particle size of less than 41 μm was obtained.

Example 1 75.5 parts by weight of the pigment-dispersed paste obtained in Production Example 4 and 0.7 of Emulgen 147 (polyoxyethylene lauryl ether manufactured by Kao Corporation, HLB = 16.3, solid content 18% by weight) 0.7 After adding 2 parts by weight, 23.4 parts by weight of the acrylic resin emulsion 1 obtained in Production Example 1 and
BERMODOL PU as Newtonian viscosity improver
2.0 parts by weight of R2130 (a nonionic polyurethane resin manufactured by Akzo Nobel Co., solid content: 30% by weight) and BERMOCOLL EBS481 as a pseudoplastic viscosity imparting agent
90 KU and 60% of PVC are obtained by mixing 8.0 parts by weight of FQ (nonionic hydroxyethylcellulose derivative manufactured by Akzo Nobel Co., 2.5% by weight of solid content), stirring with a disperser or the like, and uniformly dispersing. Was obtained. In addition, BERMODOL PUR21
The solids weight ratio of 30 to BERMOCOLL EBS481FQ was 3/1. VOC in this coating composition
Was less than 0.1% by weight from the formulation.

Example 2 2.0 parts by weight of BERMODOL PUR2130 was added.
93K in the same manner as in Example 1 except that BERMOCOLLEBS481FQ was mixed with 4.0 parts by weight.
A water-based coating composition 2 in which U and PVC were 60% was obtained. BERMODOL PUR2130 and BERMOC
The weight ratio of solid content to OLL EBS481FQ was 6/1. The content of VOC in this coating composition was less than 0.1% by weight from the formulation.

Example 3 3.0 parts by weight of BERMODOL PUR2130
97K in the same manner as in Example 1 except that BERMOCOLLEBS481FQ was mixed with 3.0 parts by weight.
A water-based coating composition 3 in which U and PVC were 60% was obtained. BERMODOL PUR2130 and BERMOC
The solid content weight ratio with OLL EBS481FQ is 12/1.
Met. The content of VOC in this coating composition was less than 0.1% by weight from the formulation.

Comparative Example 1 BERMODOL PUR2130 and BERMOCOL
An aqueous coating composition 4 having 61 KU and 60% PVC was obtained in the same manner as in Example 1 except that LEBS481FQ was not used. The content of VOC in this coating composition was less than 0.1% by weight from the formulation.

Comparative Example 2 The same procedure as in Example 1 was carried out except that BERMODOL PUR2130 was not used.
% Of an aqueous coating composition 5 was obtained. The content of VOC in this coating composition was less than 0.1% by weight from the formulation.

Comparative Example 3 An aqueous coating composition 6 of 78 KU was obtained in the same manner as in Example 1 except that BERMOCOLL EBS481FQ was not used. The content of VOC in this coating composition was less than 0.1% by weight from the formulation.

Comparative Example 4 The procedure of Example 1 was repeated except that 10.0 parts by weight of BERMODOL PUR2130 and 20.0 parts by weight of BERMOCOLLEBS481FQ were mixed.
An aqueous coating composition 7 having 36 KU and 60% PVC was obtained. BERMODOL PUR2130 and BER
The solid content ratio with MOCOLL EBS481FQ is 6
/ 1. The content of VOC in this coating composition is
It was less than 0.1% by weight from the formulation.

Evaluation Test All the evaluation results are shown in Table 1.

<Viscosity at a shear stress of 10 ⁴ sec ⁻¹ >
To 4 and the aqueous coating compositions 1 to 8 of Comparative Examples 1 to 4
The solution was diluted with ion-exchanged water to a viscosity of 70 KU at 70 ° C with a Stormer viscometer, and the viscosity at 25 ° C at a shear stress of 10 ⁴ sec ^-1 was measured by CAP VISCOMET.
It was measured using ERS (Rotary viscometer manufactured by Brookfield), and those having a value of 0.5 poise or more were regarded as acceptable.

<Coating workability> Slate plate (450 × 90
mm) was coated with Nippe Ultra Sealer II transparent (manufactured by Nippon Paint Co., Ltd.) to produce a substrate. Each of the aqueous coating compositions 1 to 8 of Examples 1 to 4 and Comparative Examples 1 to 4 was diluted with ion-exchanged water so that the viscosity of the aqueous coating composition at 25 ° C. measured by a Stormer viscometer was 70 KU. Was applied over the entire surface with a flat brush for water-based paint, and workability, sagging property and fogging were evaluated according to the following evaluation criteria. The sagging property and fog were visually evaluated after drying for 3 hours after coating. (1) Workability ○: The brush operation is smooth. △: The brush operation is slightly heavy. ×: The brush operation is light and has a slippery feeling. (2) Sagging ◎: No brush operation, smooth △: The brush operation remains. ×: Sagging (3) Fog ◎: The whole surface was completely concealed △: The left half is slightly transparent ×: The left half is clearly transparent

<Touch-up Property> After the aqueous coating compositions 1 to 8 of Examples 1 to 4 and Comparative Examples 1 to 4 were toned to beige paint colors, the viscosity at 25 ° C. measured by a Stormer viscometer was 75 KU. Dilute to make Slate board (4
50 × 90mm) Nippe Ultra Sealer I on the right half
I transparent (Nippon Paint Co., Ltd.) was applied. After drying, each diluted aqueous coating composition was applied over the entire surface with a medium wool roller. The next day, approximately 40 × 40 mm was applied to the center of each of the painted and unpainted parts of the sealer with Kodaira brush. The next day, the color difference and gloss difference between the roller-painted portion and the brush-painted portion were visually evaluated. In addition,
The evaluation criteria were as follows. ：: The brush-painted portion cannot be confirmed. ：: The brush-painted portion can hardly be confirmed. Δ: The brush-painted portion can be recognized.

<Water resistance> JIS K5663 5.9
The test was carried out in accordance with the standards described above, and those having no abnormality were evaluated as acceptable (O).

[0060]

[Table 2]

As is clear from Table 2, the water-based coating composition of the present invention was able to improve the coating workability by using two different types of viscosity-imparting agents. Also,
Even if the viscosity-imparting agent is not added in a usual amount or more, sufficient coating workability can be obtained, so that the water resistance of the obtained coating film does not decrease. Since the increase in the viscosity of the coating material itself was small, it was very easy to handle. In addition, although there was no decrease in the water resistance of the obtained coating film, good coating workability could not be obtained when the combined viscosity-imparting agent was not used or was not combined (Comparative Examples 1 to 3). Was. In addition, when the amount of the thickener was increased without performing such a combination (Comparative Example 4), the coating workability was reduced.

[0062]

The aqueous coating composition of the present invention has a content of volatile organic compounds of less than 1% by weight.
Since a viscosity imparting agent having a specific function is used in combination, fogging and sagging are good, and coating workability is excellent.

Further, the aqueous coating composition of the present invention further contains a nonionic surfactant and a pigment, and the main resin emulsion is an acrylic resin emulsion.
By setting the special value of each component in a specific range, a water-based paint having excellent touch-up properties can be obtained. This can minimize the unpleasant odor and the effect on the human body due to the volatilization of the volatile organic compound during application and drying of the paint.

Claims (10)

[Claims] An aqueous coating composition containing a resin emulsion and a thickener, wherein the content of a volatile organic compound is less than 1% by weight, wherein the thickener is a Newtonian viscosity modifier and a pseudoplastic viscosity modifier. And a content of the solid content in the coating composition of 0.3 to 3.0% by weight. 2. The aqueous coating composition according to claim 1, wherein the weight ratio of the solid content of the Newtonian viscosity-imparting agent to the pseudoplastic viscosity-imparting agent is 3/1 to 12/1. 3. The aqueous coating composition according to claim 1, wherein the Newtonian viscosity imparting agent is a nonionic polyurethane resin. 4. The aqueous coating composition according to claim 1, wherein the pseudoplastic viscosity imparting agent is a cellulose derivative. 5. The aqueous coating composition according to claim 1, wherein the emulsion resin is an acrylic resin emulsion, and the content of the acrylic resin emulsion in the coating composition is 3% by weight or more in terms of resin solid content. object. 6. The Tg of the acrylic resin emulsion is-
60 to -10 ° C, number average molecular weight of 5,000 to 20,000
The aqueous coating composition according to claim 5, wherein 0 and the acid value are 15 to 50. 7. The aqueous coating composition according to claim 1, further comprising a nonionic surfactant, the content of which is 0.2 to 5% by weight. 8. The nonionic surfactant having an HLB of 1
The aqueous coating composition according to claim 7, which has a molecular weight of 2.5 to 18.5. 9. The aqueous coating composition according to claim 1, further comprising a pigment, wherein the content is 25% or more by volume concentration of the pigment. 10. The viscosity of the coating composition measured by a rotary viscometer when the viscosity of the coating composition measured by a Stormer viscometer at 25 ° C. is 70 KU is 0.5 at a shear rate of 10 ⁴ sec ^-1 .
The aqueous coating composition according to any one of claims 1 to 9, which is at least poise.