JPH06220369A - Coating composition - Google Patents

Abstract

PURPOSE:To obtain a coating composition excellent in mixing stability and further characteristics such as adhesion to various substrates, weather, fouling and breakage resistance and thick coating properties. CONSTITUTION:This coating composition comprises an aqueous emulsion containing a homopolymer or a copolymer composed of at least one monomer unit selected from an acrylic or a methacrylic acid ester-based monomer unit, a styrenic monomer unit and a diene-based monomer unit as a dispersoid and a polyvinyl alcoholic polymer having mercapto group as a dispersing agent and a pigment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating composition having excellent suitability for a flat finish paint, a three-dimensional finish paint, a sand wall finish paint and the like.

[0002]

2. Description of the Related Art Conventionally, as exterior materials for the purpose of protecting building walls and making beautiful appearances, in addition to dry exterior materials such as decorative galvanized iron, printed plywood, various inorganic boards, and metal panels, mortar finish, tiles, etc. Wet exterior materials such as sticking and various coatings have been mainly used. However, in recent years, workability, economy,
With the increasing importance of aesthetics and the like, the spread of the wet method has been remarkable. The wet method is widely used because it can efficiently coat a large area with relatively simple work such as spraying and roll coating, has excellent waterproofness and durability, and is aesthetically preferable to various materials. There is. Among wet type exterior materials, mortar, tiled, inorganic spray materials, etc. are gradually changing to paint-based spray exterior materials using an organic polymer as a binder in order to prevent accidents due to peeling or falling off from wall surfaces. As an organic polymer,
Epoxy-based, urethane-based, vinyl acetate-based, acrylic ester-based, and synthetic rubber-based polymers are used, but water-based binders are becoming the mainstream due to recent pollution problems. The combined emulsion has been used as a prize. The main function of the exterior material is to beautifully protect and protect the wall surface, but when the base material is concrete, etc., prevention of crack propagation to the coating surface due to base cracks (even if cracks occur in the base It should be noted that the coating film should not be cracked) and the waterproof property should be given as important properties. For this purpose, various binders used for the spraying material have been studied.

Epoxy resin binders are widely used because of their excellent coating strength and adhesiveness, but they prevent cracks from spreading to the coating surface due to undercoat cracks (hereinafter referred to as undercoat crack resistance). (It is abbreviated as "property"), film-forming property, weather resistance, etc. Also, vinyl acetate emulsion is a relatively economical material and is used for some applications as a coating material, but it has poor water resistance and alkali resistance, the coating film is hard, and the resistance to base cracking is high. Is inferior,
It is rarely used in multi-layer paints for the purpose of waterproofing. Acrylic emulsions also have relatively excellent coating strength and adhesion, and also have excellent film-forming properties and weather resistance. By controlling the viscosity of the coating, it is possible to give an arbitrary coating pattern. Therefore, it is becoming widely used. However, since acrylic emulsions are generally produced by emulsion polymerization of acrylic acid ester monomers in the presence of various surfactants, vinyl acetate containing a water-soluble polymer such as polyvinyl alcohol as a protective colloid is used. Compared to system emulsions, the particle size is smaller, so when the coating film is thick, the particles also migrate (migrate) in the direction of water migration during the drying process, and as a result, the film formation speed on the coating surface and inside It has a drawback that a difference is caused and a coating film is easily cracked. Further, the base crack resistance requires the flexibility of the coating film to the extent that no crack is generated during the rapid crack propagation of the base, but in the case of an acrylic polymer, it is possible to give sufficient flexibility. However, the softening of the polymer itself causes an increase in tackiness on the surface of the coating film, which causes problems such as deterioration of stain resistance, which is not preferable in practical use. Further, the elasticity at a low temperature increases as the flexibility is imparted, but the softening at a high temperature is remarkable and the physical properties of the coating film are deteriorated. The temperature dependence of the physical properties of the coating film is important as the performance required for the binder for paint. The temperature of the building wall surface may change from -10 ° C to 60 ° C from winter to summer, and the coating film is required to maintain desirable performance in this temperature range. Most organic polymers are usually
At low temperature, it loses elasticity and hardens, and on the contrary, it tends to soften at high temperature, and none of them show constant properties over a wide temperature range. In particular, the resin emulsions as described above,
This tendency is remarkable, and if importance is attached to flexibility at low temperature, softening occurs at high temperature, physical properties of the coating film deteriorate, and use becomes unusable. On the contrary, if importance is attached to elasticity at high temperature, there are problems such as a decrease in elongation at room temperature and a decrease in base crack resistance due to curing at low temperature. Such a problem is caused by the essential property of the thermoplastic polymer, and the fundamental solution is extremely difficult.

As polymers having excellent physical properties even when the temperature changes, there are rubber polymers, and paints having excellent coating performance even at low temperature and high temperature have been developed. For example, butyl rubber, chloroprene rubber,
Solvent-based paints using fluororubber, silicone rubber, halogenated polyethylene rubber, etc. are known to have excellent coating performance in a wide temperature range, but they are extremely disadvantageous in terms of cost and Due to pollution problems caused by scattering, it is used only for extremely limited purposes. The butadiene rubber latex is economically excellent and has excellent coating performance in a wide temperature range, but its weather resistance is inferior due to deterioration of the polymer due to the breakage of the double bond of butadiene. Is rarely used in. The weather resistance of the coating film of butadiene-based paint is related to the amount of butadiene in the polymer and is gradually improved by reducing the amount of butadiene, but if the amount of butadiene is reduced too much, the elasticity of the coating film is lost and Hardening at high temperature and softening at high temperature, and the physical properties at room temperature also deteriorate. Tokusho Sho 6
JP-A 1-38742 discloses a paint using a butadiene rubber latex which has excellent coating performance from low temperature to high temperature and is also excellent in weather resistance, and the amount of butadiene in the butadiene rubber latex and the gel in the polymer. It is disclosed that the one whose content is appropriately controlled is effective. However, since this butadiene rubber latex is produced by an emulsion polymerization method in the presence of various surfactants as in the case of the above acrylic emulsion, it is generally a protective colloid for water-soluble polymers such as polyvinyl alcohol. The particle size is smaller than that of the above, and therefore, when the paint is applied thickly, there is a drawback that cracks or lack of smoothness of the coating film due to migration easily occur.

[0005]

Under the circumstances, the present invention is excellent in mixing stability, and has excellent adhesion to various substrates, weather resistance, stain resistance, breakage resistance, thick coating property, etc. It is an object of the present invention to provide a coating composition having excellent properties.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to develop a coating composition having the above-mentioned preferable properties, and as a result, have identified a polyvinyl alcohol having a mercapto group at a terminal as a dispersant. It has been found that a coating composition prepared by blending a pigment in the above aqueous emulsion can meet the purpose. The present invention has been completed based on such findings. That is, the present invention provides, as a dispersoid, at least one unit selected from acrylic acid ester-based monomer units, methacrylic acid ester-based monomer units, styrene-based monomer units, and diene-based monomer units. Containing a homopolymer or copolymer consisting of a monomer unit,
Further, the present invention provides a coating composition characterized by containing an aqueous emulsion containing a polyvinyl alcohol-based polymer having a mercapto group at a terminal as a dispersant and a pigment.

Each component used in the coating composition of the present invention will be described. The aqueous emulsion used in the coating composition of the present invention contains, as a dispersoid, an acrylic acid ester monomer unit, a methacrylic acid ester monomer unit, a styrene monomer unit and a diene monomer unit. It contains a homopolymer or a copolymer composed of at least one monomer unit selected from (Meth) acrylic acid ester-based monomer [(meth) acrylic acid means acrylic acid or methacrylic acid. The same applies hereinafter. ], For example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth)
2-ethylhexyl acrylate, dodecyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate,
Examples thereof include dimethylaminoethyl (meth) acrylate, quaternary products thereof, and glycidyl methacrylate. On the other hand, examples of the styrene-based monomer include styrene and α-
Methyl styrene, p-methyl styrene sulfonic acid, its sodium, potassium salt, etc. are mentioned. Also,
Examples of the diene-based monomer include butadiene, isoprene and chloroprene. These monomers may be used alone or in combination of two or more.

The aqueous emulsion used in the present invention can also be copolymerized with a monomer other than the (meth) acrylic acid ester-based, styrene-based, and diene-based monomers as long as the performance is not impaired. Examples of the copolymerizable monomers include olefins such as ethylene, propylene and isobutylene, vinyl formates such as vinyl formate, vinyl acetate, vinyl propionate and vinyl versatate, vinyl chloride, vinyl fluoride, vinylidene chloride and vinylidene fluoride. Halogenated olefins such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid,
Α, β-ethylenically unsaturated carboxylic acids such as citraconic acid and salts thereof, (meth) acrylamide, N-methylol (meth) acrylamide, N, N′-dimethylacrylamide, acrylamide 2-methylpropanesulfonic acid and sodium salt thereof And other (meth) acrylamide-based monomers, and other monomers such as vinylpyridine and N-vinylpyrrolidone.

The aqueous emulsion used in the present invention is
The dispersant is a polyvinyl alcohol (PVA) -based polymer having a mercapto group at the terminal, and preferably the PV
Obtained by emulsion (co) polymerizing one or more monomers selected from the above (meth) acrylic acid ester-based monomers, styrene-based monomers and diene-based monomers in the presence of the A-based polymer. Is an aqueous emulsion that is used. By using PVA having a mercapto group as a dispersant in the aqueous emulsion of the present invention, a stable emulsion cannot be obtained with a conventional PVA-based polymer (meth) acrylic acid ester-based, styrene-based, diene-based single emulsion. A stable emulsion can be obtained even in the monomer form. That is, when an extremely active mercapto group is introduced into a PVA-based polymer in a radical polymerization reaction, it is highly effective for (meth) acrylic acid ester-based, styrene-based, and diene-based monomers having relatively low radical reactivity. It strongly reacts with each other and chemically bonds the particles to the PVA-based polymer to firmly form an adsorption hydration layer that contributes to the stability of the aqueous emulsion. The above PVA-based polymer may be a polymer having a mercapto group in the main chain of the PVA molecule, but by forming a disulfide bond by oxidation of PVA itself,
It may become insoluble. Therefore, in the present invention, a PVA-based polymer having a mercapto group only at one end of the molecule is easy to handle without fear of insolubilization and is preferably used. A PVA-based polymer having a mercapto group only at one end of such a molecule is a polyvinyl ester-based polymer obtained by polymerizing a vinyl-based monomer mainly containing vinyl esters in the presence of thiol acid by a conventional method. It can be obtained by saponification, and its production method will be described in detail below.

First, the thiol acid used here is -COS.
It includes an organic thiol acid having an H group. Examples thereof include thiol acetic acid, thiol propionic acid, thiol butyric acid, and thiol valeric acid. Among them, thiol acetic acid is most preferable because of its degradability. Further, vinyl esters can be used as long as they are radically polymerizable vinyl esters. For example, vinyl formate, vinyl acetate, vinyl propionate, vinyl versatate, vinyl laurate, vinyl stearate and the like can be mentioned. Among them, vinyl acetate is the most polymerizable and preferred. It is also possible to copolymerize these vinyl esters with a monomer copolymerizable therewith. Examples of the copolymerizable monomer include ethylene, propylene, isobutylene, acrylic acid, methacrylic acid, maleic anhydride, maleic acid, fumaric acid, itaconic acid or salts thereof or alkyl esters thereof, acrylonitrile, methacrylonitrile, Acrylamide, methacrylamide, trimethyl- (3-acrylamido-3-dimethylpropyl) -ammonium chloride, ethyl vinyl ether, butyl vinyl ether,
Examples thereof include N-vinylpyrrolidone, vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, vinylidene fluoride, tetrafluoroethylene, sodium vinyl sulfonate and sodium allyl sulfonate.

Polymerization of vinyl monomers mainly composed of vinyl esters such as vinyl acetate in the presence of thiol acid is carried out in the presence of a radical polymerization initiator in the bulk polymerization method, solution polymerization method, pearl polymerization method, Although any method such as an emulsion polymerization method can be used, the solution polymerization method using methanol as a solvent is industrially most advantageous. The amount and method of addition of the thiol acid present during the polymerization to the polymerization system are not particularly limited and should be appropriately determined according to the physical properties of the desired PVA-based polymer. As a polymerization method, a known method such as a batch method, a semi-continuous method, or a continuous method can be adopted.

As the radical polymerization initiator, for example, 2,
Known radical polymerization initiators such as 2'-azobisisobutyronitrile, benzoyl peroxide, and carbonate carbonate can be used, but azo initiators such as 2,2'-azobisisobutyronitrile are easy to handle and preferable. . Radiation, electron beam, etc. can also be used. As the polymerization temperature, it is desirable to adopt an appropriate temperature depending on the kind of the initiator used, but it is usually selected from the range of 30 to 90 ° C. After polymerization for a predetermined period of time, unpolymerized vinyl esters are removed by a usual method to obtain a polyvinyl ester polymer having a thiol ester group at the terminal.

The polyvinyl ester polymer thus obtained is saponified by a conventional method, but it is usually advantageous to carry out the polymer as an alcohol solution, especially a methanol solution. As the alcohol, not only an anhydride but also a small amount of water-containing alcohol may be used according to the purpose, and an organic solvent such as methyl acetate or ethyl acetate may be optionally contained. The saponification temperature is usually selected from the range of 10 to 70 ° C. As the saponification catalyst, for example, alkaline catalysts such as sodium hydroxide, potassium hydroxide, sodium methylate, and potassium methylate are preferable. The amount of the catalyst used is appropriately determined depending on the degree of saponification, the amount of water, etc., but it is desirable to use the catalyst in a molar ratio of 0.0001 or more, preferably 0.002 or more with respect to the vinyl ester unit. On the other hand, if the amount of alkali is too large, it becomes difficult to remove the residual alkali from the polymer, and the polymer is colored, which is not preferable, and the molar ratio is preferably 0.2 or less. If the polyvinyl ester-based polymer contains a component that reacts with an alkali catalyst such as a carboxyl group or its ester group and consumes alkali, use the amount of the alkali catalyst added to the consumption amount. Is desirable.

By this saponification reaction, the terminal thiol ester of the polyvinyl ester polymer having a thiol ester group at the terminal and the vinyl ester bond in the main chain are saponified, and the polymer terminal becomes a mercapto group and the main chain becomes a vinyl alcohol. However, the degree of saponification of the vinyl ester unit in the main chain can be changed according to the purpose of use. The polymer precipitated after the saponification reaction can be usually obtained as a white powder by purifying by a known method such as washing with methanol and removing impurities such as residual alkali and an alkali metal salt of acetic acid and drying.

The method for producing the PVA-based polymer having a mercapto group at the terminal used in the present invention has been described above. The degree of polymerization of this PVA-based polymer is preferably 3500 or less. Although the degree of saponification cannot be uniquely stated, it is preferably 70 mol% or more from the viewpoint of water solubility. The amount of the PVA-based polymer thus obtained is 1 to 20 with respect to the amount of the (meth) acrylic acid ester-based monomer, the styrene-based monomer, the diene-based monomer, or the like. %, Especially 2 to 10% by weight is preferred. When the amount of the PVA-based polymer used is less than 1% by weight based on the amount of the monomer, the emulsion polymerization stability decreases, and a stable aqueous emulsion is difficult to obtain, which is not preferable. On the other hand, when the amount of the PVA-based polymer used exceeds 20% by weight, water-stopping performance and adhesion to the finishing treatment material (structure) may not be sufficiently exhibited, which may cause a problem.

Using the PVA polymer as a dispersant,
In carrying out emulsion (co) polymerization of one or more monomers selected from (meth) acrylic acid ester-based monomers, styrene-based monomers and diene-based monomers, water, a dispersant and The above-mentioned unsaturated monomer may be added temporarily or continuously in the presence of a polymerization initiator, and any ordinary emulsion polymerization method such as heating and stirring may be carried out. A method of continuously adding a mixture of a PVA-based polymer aqueous solution and an emulsion may be carried out. As the polymerization initiator, a redox system composed of a mercapto group at the PVA end and a water-soluble oxidizing agent such as potassium bromate, potassium persulfate, hydrogen peroxide can also be used. Among them, potassium bromate is usually used under normal polymerization conditions. PV alone does not generate radicals
It is a particularly preferred initiator because it decomposes only by a redox reaction with the mercapto group at the A terminal to generate a radical, which effectively forms a block copolymer with PVA and thereby enhances the stabilizing effect. It is also possible to use potassium bromate at the start of the polymerization, and then to add another oxidizing agent, so that the oxidizing agent can be used in combination. When emulsion polymerization is carried out using the PVA polymer having a mercapto group, it is desirable that the polymerization system is acidic. This is because under acidic conditions, the mercapto group is ionically added to the double bond of the monomer and disappears at a large rate, and the polymerization efficiency is significantly reduced. All polymerization operations are performed at pH 6 or less, preferably pH 5 or less. It is desirable to carry out.

The aqueous emulsion according to the present invention contains the above-mentioned mercapto group-containing PV as an emulsion dispersion stabilizer.
In addition to A-based polymers, conventionally known nonionic surfactants, anionic surfactants, cationic surfactants, conventionally known unmodified PVA, various modified PVA, and water-soluble cellulose such as hydroxyethyl cellulose. Water-soluble polymers can be used in combination as long as they do not impair the performance as a paint. As the aqueous emulsion used in the present invention, the aqueous emulsion obtained by the above method may be used as it is, but various aqueous emulsions can be added if necessary. Examples of such an aqueous emulsion include polyvinyl acetate emulsion, ethylene-vinyl acetate copolymer emulsion, polychloroprene emulsion, polybutadiene emulsion, styrene-butadiene copolymer emulsion, butadiene-acrylonitrile copolymer emulsion, butyl rubber emulsion,
Polyacrylic ester emulsion, polyvinyl chloride emulsion, polyvinylidene chloride emulsion and the like can be mentioned.

The coating composition of the present invention comprises the above-mentioned aqueous emulsion and a pigment. Here, the pigment is not particularly limited, and various natural pigments, synthetic inorganic pigments and synthetic organic pigments can be used. More specifically, coloring pigments (titanium white, iron yellow, ultramarine blue, cadmium yellow, red iron oxide, chrome yellow, carbon black, cyanine pigment, azo pigment, triphenylmethane pigment, quinoline pigment, anthraquinone pigment,
Phthalocyanine pigments, etc., extender pigments (barium sulfate, calcium carbonate, kaolin, talc, silica, alumina, perlite, silica sand, etc.), special pigments (rust preventive pigments, luminescent pigments, thermochromic pigments, etc.), fibrous or flaky pigments Specific inorganic pigments (asbestos, rock wool, mica, etc.) can be mentioned, and these pigments can be used alone or in combination of two or more kinds. The amount of the pigment blended is preferably 40 to 400 parts by weight, more preferably 60 to 300 parts by weight, based on 100 parts by weight of the resin content of the aqueous emulsion. When the amount of the pigment added is less than 40 parts by weight, weather resistance is deteriorated such as swelling of the coating film, while when it exceeds 400 parts by weight, the flexibility and elasticity of the coating film are lost. Likely to happen.

In preparing the coating composition of the present invention, the pigment is mixed with the above-mentioned aqueous emulsion, and further,
Various additives used when preparing ordinary water-based emulsion type paints, such as methyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, polyacrylic acid salts, polyacrylamide, thickeners such as polyvinylpyrrolidone, tripolyphosphoric acid, hexametaphosphoric acid, etc. Condensed phosphates, anionic, nonionic or cationic surfactants, dispersants such as styrene-maleic anhydride half ester salts, diisobutylene-maleic anhydride half ester salts, defoaming agents, antifungal agents, preservatives Agents, film forming aids, antiaging agents, antifreezing agents, etc. can be added as necessary. The obtained paint is applied by a general method using a roll, a trowel, a brush, a spray gun or the like. The paint according to the present invention can be suitably used for various surfaces such as wall surfaces, floor surfaces, and ceiling surfaces made of concrete, mortar, ALC plates, flexible plates, metal plates, plywood and the like. For the purpose of improving the adhesion to the substrate, waterproofness, weather resistance, aesthetics, etc., a substrate treatment agent, a top coat agent, etc. can be used.

[0020]

EXAMPLES The present invention will be specifically described below with reference to examples, but these examples do not limit the present invention in any way. All parts or percentages are by weight unless otherwise specified. The test methods used in the examples are as follows. (1) Miscibility of Pigment and Inorganic Filler The dispersion state when the pigment and the inorganic filler were added to the aqueous emulsion was evaluated on the basis of the following three criteria. ◯: Good dispersion condition Δ: Viscosity increased ×: Rough feeling and solidification

(2) Thick coating property The coating composition was sprayed onto an asbestos slate board using a gun (nozzle diameter 6.5).
mm, spraying pressure 3 kg / cm ² ) about 2.0 kg /
It was sprayed to a weight of cm ² and dried at 20 ° C. for 7 days. Observe the state of the coating film surface of this paint spray board,
The following criteria evaluated 3 grades. ◯: Smooth coating film formation △: Slightly uneven coating film formation ×: Cracks in coating film (3) Adhesion 2. Apply coating composition to asbestos slate plate of 7 × 70 × 70 mm.
Spray at a weight of 0 kg / cm ² and run at 20 ° C for 7
Allowed to dry for days. Standard state according to JIS A6910,
The wet adhesion strength was measured. In addition, the adhesion strength in a wet state is measured in a wet state after being immersed in water at 20 ° C. for 24 hours.

(4) Adhesiveness (stain resistance) After the defoaming coating composition was dried on a glass plate, the film thickness was 2 m.
After being coated so as to have a thickness of m, it was dried at room temperature for 3 days, peeled from the glass plate, turned over, and dried for another 4 days. The tack of the surface of the test body thus obtained was judged by the finger touch method according to the following criteria. ◯: Almost no adhesion X: Large adhesion (5) Tensile test The test body prepared in (4) was punched with JIS No. 2 dumbbell in accordance with JIS K6301, -10 ° C, 25 ° C and 6
The tensile strength was measured at each temperature of 0 ° C.

(6) Weather resistance The surface of the test body of (2) was top-coated with acrylic urethane enamel and exposed to a weather meter (Xenon Weathering Tester, manufactured by Toyo Seiki Seisakusho) for 300 hours, and evaluated according to the following criteria. did. ◎: No change ○: Very slight discoloration △: Discoloration ×: Significant discoloration (7) Breaking resistance (underground crack resistance) (2) Tensile speed of 20 mm / min according to the zero span tension test method using the test specimen I went there. Growth is half
Displayed as stress elongation.

Example 1 A PVA having a mercapto group at its end (PVA-3; degree of polymerization: 500, degree of saponification: 88.5) was placed in a 1-liter glass container equipped with a reflux condenser, a dropping funnel, a thermometer, and a nitrogen blowing port.
15% (mol%) by heating with 280 g of ion-exchanged water,
The pH was adjusted to 3.5 with dilute sulfuric acid. Then 140 rpm
While stirring at 40 g, 40 g of methyl methacrylate and 60 g of butyl acrylate were charged, the temperature was raised to 60 ° C., and then 10 g of a 5% ammonium persulfate aqueous solution was added to initiate polymerization. 15 minutes after starting the polymerization, methyl methacrylate 8
0 g and 120 g of butyl acrylate were continuously added over 2 hours. After 5 hours, the polymerization rate was 99.9% and the mixture was cooled. PH = 6 of the produced emulsion with aqueous ammonia.
It was adjusted to 8 to obtain an aqueous emulsion having a solid content concentration of 50.3%, a viscosity of 800 cp, and an average particle size of 0.7 μm by a dynamic light scattering method (DLS method). While stirring in 100 parts by weight of this aqueous emulsion, 3 parts of a 3% aqueous solution of sodium hexametaphosphate, 2 parts of a 3% aqueous solution of Metroses 15000 (methyl cellulose manufactured by Shin-Etsu Chemical Co., Ltd.) and Nopco 8034.
(Antifoam manufactured by San Nopco Co., Ltd.) 0.5 part was added, and ground calcium carbonate (manufactured by Shiraishi Industry Co., Ltd., Whiten P)
-40) 56 parts, rutile type titanium oxide 16.5 parts and talc 37.5 parts were added and uniformly mixed. The coating composition thus obtained was tested and the results are shown in Table 1.

Example 2 12 g of PVA having a mercapto group at the end (PVA-2; degree of polymerization: 350, degree of saponification: 96.0 mol%) dissolved in 290 g of ion-exchanged water with heating was charged with a nitrogen inlet and a thermometer. It was placed in a pressure-resistant autoclave equipped with it. After adjusting the pH to 4.0 with dilute sulfuric acid, 210 g of styrene and then 90 g of butadiene were charged from a pressure meter, the temperature was raised to 70 ° C., and 10 g of a 2% aqueous solution of potassium persulfate was injected under pressure to initiate polymerization. Pressure is decreased with progress of the polymerization from 3.9 kg / cm ^2, 15 hours later 0.3 kg / cm ² mm was 99.3% when calculated polymerization rate. The obtained emulsion was adjusted to pH = 6.8 with aqueous ammonia to obtain an aqueous emulsion having a solid content concentration of 49.2%, a viscosity of 900 cp, and an average particle size of 0.6 μm by a dynamic light scattering method. Using this aqueous emulsion, a coating composition was prepared in the same manner as in Example 1, its performance was evaluated, and the results are shown in Table 1.

Example 3 A PVA having a mercapto group at its end (PVA-3; degree of polymerization 600, degree of saponification 88.5) was placed in a 1-liter glass container equipped with a reflux condenser, a dropping funnel, a thermometer, and a nitrogen blowing port.
18% (mol%) by heating with 280 g of ion-exchanged water,
The pH was adjusted to 3.5 with dilute sulfuric acid. Then 140 rpm
While stirring at 45 g, 45 g of styrene and 45 g of 2-ethylhexyl acrylate were charged, the temperature was raised to 70 ° C., and 10 g of a 5% ammonium persulfate aqueous solution was added to initiate polymerization. 15 minutes after starting the polymerization, 105 g of styrene and 105 g of 2-ethylhexyl acrylate were continuously added over 3 hours. After 6 hours, the polymerization rate was 99.5% and the mixture was cooled. PH of the resulting emulsion with ammonia water
= 6.8, solid concentration 50.2%, viscosity 1100c
p, an aqueous emulsion having an average particle size of 0.6 μm was obtained by the dynamic light scattering method. Example 1 using this aqueous emulsion
A coating composition was prepared in the same manner as above, the performance thereof was evaluated, and the results are shown in Table 1.

Comparative Example 1 PVA having a mercapto group at the terminal used in Example 1
The same operation as in Example 1 was carried out except that 12 g of a nonionic surfactant (polyoxyethylene (40) nonylphenyl ether manufactured by Sanyo Kasei Co., Ltd., Nonipol 200) was used instead of (PVA-1), The pH of the produced emulsion was adjusted to 6.8 with aqueous ammonia, and the solid content concentration was adjusted to 5.0.
%, Viscosity 70 cp, average particle size 0.2μ by dynamic light scattering method
m aqueous emulsion was obtained. Then, using this aqueous emulsion, a coating composition was prepared in the same manner as in Example 1, the performance thereof was evaluated, and the results are shown in Table 1.

Comparative Example 2 PVA having a mercapto group at the terminal used in Example 2
Instead of (PVA-2), 9 g of an anionic surfactant (Sanyo Kasei Co., Ltd. alkyl diphenyl ether disulfonic acid sodium salt, Sandet BL) was used.
The same operation as in Example 2 was carried out to adjust the pH of the resulting emulsion to 6.5 with aqueous ammonia, to obtain an aqueous emulsion having a solid content concentration of 49.0%, a viscosity of 800 cp, and an average particle size of 0.1 μm by the dynamic light scattering method. Obtained. Then, using this aqueous emulsion, a coating composition was prepared in the same manner as in Example 1,
The performance was evaluated and the results are shown in Table 1.

Comparative Example 3 PVA having a mercapto group at the end used in Example 3
Instead of (PVA-1), 9 g of a nonionic surfactant (polyoxyethylene (40) nonylphenyl ether manufactured by Sanyo Chemical Co., Ltd., Nonipol 200) and an anionic surfactant (alkyl diphenyl ether manufactured by Sanyo Chemical Co., Ltd.) Disulfonic acid sodium salt, Sandet BL) 3g
The same operation as in Example 3 was carried out except that the resulting emulsion was adjusted to pH = 6.8 with aqueous ammonia, the solid content concentration was 50.2%, the viscosity was 100 cp, and the average particle size by dynamic light scattering method was 0. A 0.2 μm aqueous emulsion was obtained. Then, using this aqueous emulsion, a coating composition was prepared in the same manner as in Example 1, the performance thereof was evaluated, and the results are shown in Table 1.

Comparative Example 4 An unmodified PVA (Kuraray, P) was placed in a 1-liter glass container equipped with a reflux condenser, a dropping funnel, a thermometer, and a nitrogen inlet.
15 g of VA-217; degree of polymerization 1700, degree of saponification 89.0 mol%) was dissolved by heating with 290 g of ion-exchanged water, and pH was adjusted to 4.5 with diluted sulfuric acid. Next, 300 g of vinyl acetate was charged while stirring at 140 rpm, the temperature was raised to 60 ° C., and then polymerization was started using a redox initiator of 0.5% hydrogen peroxide solution-2% tartaric acid aqueous solution. After 2 hours, the polymerization rate was 99.2% and the mixture was cooled. The pH of the produced emulsion was adjusted to 5.8 with aqueous ammonia, and the solid content concentration was 49.2%.
An aqueous emulsion having a viscosity of 3500 cp and an average particle diameter of 0.5 μm was obtained by a dynamic light scattering method (DLS method). Then, using this aqueous emulsion, a coating composition was prepared in the same manner as in Example 1, the performance thereof was evaluated, and the results are shown in Table 1.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

As is apparent from Table 1 above, the coating composition of the present invention is excellent in mixing stability, and is also excellent in thick coatability, adhesion, weather resistance, stain resistance, and breakage resistance.

[0035]

As described above, the coating composition of the present invention has a good compatibility with the pigment and the inorganic filler because the aqueous emulsion thereof is stable and maintains a good dispersion state, It is possible to produce a coating film with excellent coatability and various properties such as adhesion, weather resistance, stain resistance, and breakage resistance. Therefore, the paint composition of the present invention is effective as various paints such as flat finish paint, three-dimensional finish paint, and sand wall finish paint.

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location C09D 129/02 LGT 6904-4J 133/00 PGF 7921-4J

Claims (1)

[Claims] 1. A dispersoid of at least one unit selected from acrylic acid ester-based monomer units, methacrylic acid ester-based monomer units, styrene-based monomer units, and diene-based monomer units. A coating composition comprising an aqueous emulsion containing a homopolymer or copolymer composed of body units and a polyvinyl alcohol-based polymer having a mercapto group at a terminal as a dispersant, and a pigment.