JP6671531B1 - Aqueous paint composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous coating composition capable of forming a coating film having good water resistance and weather resistance. An aqueous coating composition comprising a fluororesin emulsion (A) and an acrylic silicone resin emulsion (B), wherein the fluororesin emulsion (A) is a fluorine-containing seed polymerization emulsion, Aqueous coating composition, wherein the SP value of the acrylic silicone resin emulsion (B) is in the range of 9.5 to 10.9. [Selection diagram] None

Description

  The present invention relates to an aqueous coating composition containing a fluororesin emulsion (A) and an acrylic silicone resin emulsion (B).

  Background Art Various exterior paints are applied to the walls of buildings such as houses and buildings in order to maintain quality and appearance while being exposed to the wind and rain and receiving direct sunlight. Such paints are required to have basic performances such as weather resistance, weather resistance, water resistance, discoloration resistance, and adhesion to a base material, but in recent years, there have been problems such as environmental pollution, safety in painting work, hygiene, and the like. Is becoming more aqueous.

  When long-term weather resistance and durability as described above are required, a coating composition containing a fluorine resin containing a fluorine atom (for example, a fluorine resin emulsion) is used. However, coating compositions containing fluororesin emulsions are generally expensive. In addition, in the case of the aqueous coating composition containing a fluororesin emulsion, there has been a case where a recent demand for further improvement in performance, particularly, a water resistance cannot be sufficiently satisfied.

  JP-A-2006-138223 (Patent Document 1) includes a dispersion in which a fluoropolymer (α) and an acrylic silicone (β) are dispersed or dissolved in an aqueous medium, and the fluoropolymer ( α) and the acrylic silicone (β) have a compounding ratio “α / β” (mass ratio of dry solid content) of 90/10 to 30/70, and the number average of the acrylic silicone (β) in the dispersion is An aqueous coating composition having a particle size of 50 to 150 nm is described (Claim 1).

JP-A-2006-223223

  Aqueous coating compositions containing fluororesin emulsions are used in applications where long-term weather resistance and durability are required. However, a coating film formed by an aqueous coating composition containing a fluororesin emulsion may not have sufficient water resistance. Patent Document 1 discloses an aqueous coating composition containing a fluoropolymer (α) and acrylic silicone (β) as an aqueous coating composition capable of forming a coating film having excellent weather resistance and water resistance. . However, it has been found that the appearance of the formed coating film may be inferior depending on the types of the fluoropolymer and acrylic silicone used.

  An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide an aqueous coating composition capable of forming a coating film having good water resistance and weather resistance, and a specific fluororesin. It is an object of the present invention to provide an aqueous coating composition containing the emulsion (A) and the acrylic silicone resin emulsion (B).

In order to solve the above problems, the present invention provides the following aspects.
[1]
A fluororesin emulsion (A) and an acrylic silicone resin emulsion (B),
An aqueous coating composition comprising:
The fluorine resin emulsion (A) is a fluorine-containing seed polymerization emulsion, and the SP value of the acrylic silicone resin emulsion (B) is in the range of 9.5 to 10.9.
Aqueous coating composition.
[2]
An aqueous coating composition, wherein the acrylic silicone resin emulsion (B) has a hydroxyl value of 30 mgKOH / g or less.
[3]
The acrylic silicone resin emulsion (B) is an emulsion polymer of a monomer mixture,
The monomer mixture contains an alkoxysilyl group-containing radically polymerizable unsaturated monomer,
Aqueous coating composition.
[4]
The monomer mixture further comprises one or more selected from the group consisting of methyl methacrylate, n-butyl acrylate and 2-ethylhexyl acrylate,
The total amount of one or more selected from the group consisting of methyl methacrylate, n-butyl acrylate and 2-ethylhexyl acrylate with respect to 100 parts by mass of the monomer mixture is in the range of 20 to 99.9 parts by mass. Is,
Aqueous coating composition.
[5]
An aqueous coating composition, wherein the fluororesin emulsion (A) is an emulsion of a seed polymer of a radically polymerizable unsaturated monomer using fluoropolymer particles as seeds.
[6]
The solid content mass ratio of the fluororesin emulsion (A) and the acrylic silicone resin emulsion (B) contained in the aqueous coating composition is (A) :( B) = 20: 80 to 90:10. , Aqueous coating compositions.
[7]
The haze value of a mixture of a fluororesin emulsion (A) and an acrylic silicone resin emulsion (B) having a solid content mass ratio of 50:50 and a dry coating film thickness of 50 μm is 4.10 or less. And the aqueous coating composition.
[8]
The above-mentioned aqueous coating composition which is an aqueous coating composition for building material coating or building coating.
[9]
A method for producing the above aqueous coating composition, comprising the following steps:
A step of subjecting a radical polymerizable unsaturated monomer to seed polymerization of the fluoropolymer particles in an aqueous dispersion of the fluoropolymer particles to obtain a fluororesin emulsion (A);
A step of emulsion-polymerizing a monomer mixture containing an alkoxysilyl group-containing radically polymerizable unsaturated monomer to obtain an acrylic silicone resin emulsion (B), and mixing the fluororesin emulsion (A) and the acrylic silicone resin emulsion (B) A step of obtaining an aqueous coating composition,
Including,
A method for producing an aqueous coating composition.

  The aqueous coating composition contains a specific fluororesin emulsion (A) and an acrylic silicone resin emulsion (B). A coating film formed by using the above-mentioned aqueous coating composition has an advantage that, in addition to being excellent in weather resistance, it also has excellent blocking resistance and water resistance.

  The aqueous coating composition contains a fluororesin emulsion (A) and an acrylic silicone resin emulsion (B). Hereinafter, each component is described.

Fluororesin emulsion (A)
The aqueous coating composition contains a fluororesin emulsion (A). As the above-mentioned fluororesin emulsion (A), an emulsion of a seed polymer of a radical polymerizable unsaturated monomer using a fluoropolymer particle as a seed (fluorine-containing seed polymerization emulsion) is suitably used.

The fluororesin emulsion (A) is, for example,
Aqueous dispersion polymerization of a monomer containing at least one fluoroolefin in the presence of a surfactant to produce an aqueous dispersion of fluoropolymer (a) particles, and fluoropolymer (a) particles In which the radical polymerizable unsaturated monomer is seed-polymerized to particles of the fluoropolymer (a) in the aqueous dispersion of (a) to obtain a fluororesin emulsion (A). .

  The fluoroolefin used for preparing the fluoropolymer (a) particles is not particularly limited, and examples thereof include tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and perfluoro (alkyl vinyl ether) (PAVE). Non-perfluoroolefins such as chlorotrifluoroethylene (CTFE), vinyl fluoride (VF), vinylidene fluoride (VdF), trifluoroethylene, trifluoropropylene, pentafluoropropylene, tetrafluoropropylene and hexafluoroisobutene And olefins. Specific examples of perfluoro (alkyl vinyl ether) (PAVE) include, for example, perfluoro (methyl vinyl ether) (PMVE), perfluoro (ethyl vinyl ether) (PEVE), and perfluoro (propyl vinyl ether) (PPVE).

  Further, as the fluoroolefin, a functional group-containing fluoroolefin monomer can also be used. Examples of the functional group of the functional group-containing fluoroolefin include a hydroxyl group, a carboxylic acid group, a sulfonic acid group, a carboxylic acid group, and an epoxy group.

  These may be used alone or in combination of two or more. Further, a non-fluorinated monomer copolymerizable with a fluoroolefin may be used in combination.

As the surfactant used for preparing the fluoropolymer (a) particles, any of a fluorine-based surfactant and a non-fluorine-based surfactant can be used.
As the fluorine-based surfactant, an anionic fluorine-based surfactant is preferable. As the fluorinated surfactant, for example, partial fluorination having a hydrophobic group having a CH bond and a CF bond and a hydrophilic group such as a carboxylic acid group, a sulfonic acid group, a phosphoric acid group and a salt thereof. Surfactants can be suitably used.
As the non-fluorinated surfactant, an anionic non-fluorinated surfactant is preferable. As the non-fluorinated surfactant, for example, a surfactant having a hydrophobic group containing an unsaturated double bond group and a hydrophilic group such as a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, and a salt thereof is preferable. Can be used. Specific examples of such a non-fluorinated surfactant include, for example, Aqualon HS-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.).
Further, if necessary, a surfactant other than the above, which is usually used by those skilled in the art, may be contained.

  The fluoropolymer (a) particles can be prepared by performing aqueous dispersion polymerization in the presence of the surfactant. Examples of the aqueous dispersion polymerization include emulsion polymerization and suspension polymerization. Emulsion polymerization is particularly preferable because a large number of polymer particles having a small particle diameter are produced. For example, in the case of emulsion polymerization, the use amount of the surfactant is preferably 0.01 to 5% by mass, more preferably 0.02 to 4% by mass, based on the total amount of water as a medium.

  The polymerization temperature is not particularly limited and can be selected according to the type of the polymerization initiator. The polymerization temperature is, for example, preferably from 40 to 120 ° C, and more preferably from 50 to 100 ° C. In the polymerization, the monomer may be supplied continuously or sequentially.

  As the polymerization initiator, a water-soluble radical polymerization initiator can be suitably used. Specific examples of the water-soluble radical polymerization initiator include, for example, persulfuric acid, perboric acid, perchloric acid, perphosphoric acid, ammonium salts of potassium percarbonate, potassium salts, sodium salts and the like are preferable, and ammonium persulfate and potassium persulfate are preferable. Particularly preferred. The method of adding the polymerization initiator is not particularly limited. For example, a concentration of several ppm or more with respect to water as a medium can be added all at once in the beginning of polymerization, or sequentially, or continuously. .

  In the production method of the present invention, a molecular weight modifier and the like may be further added. The molecular weight modifier may be added all at once in the beginning, or may be added continuously or dividedly. Examples of the molecular weight regulator include, for example, dimethyl malonate, diethyl malonate, methyl acetate, ethyl acetate, butyl acetate, esters such as dimethyl succinate, isopentane, isopropanol, acetone, various mercaptans, carbon tetrachloride, cyclohexane, Monoiodomethane, 1-iodomethane, 1-iodopropane, isopropyl iodide, diiodomethane, 1,2-diiodomethane, 1,3-diiodopropane and the like can be mentioned.

  The polymerization pressure can be appropriately selected within the range of 0.1 to 10 MPa, and more preferably 0.2 to 8 MPa, and within this range, the pressure may be low (0.1 to 1 MPa) or high ( 1 to 10 MPa).

  As the stirring means, for example, a known stirring means using an anchor blade, a turbine blade, an inclined blade, a large blade, or the like can be used. For example, stirring with a large blade called a full zone or a max blend is preferable from the viewpoints of good monomer diffusion and polymer dispersion stability. The stirring device may be a horizontal stirring device or a vertical stirring device. The average particle diameter of the fluoropolymer (a) particles obtained by the above step is preferably 100 to 200 nm. The number average molecular weight of the fluoropolymer is preferably 10,000 to 1,000,000.

  In the present specification, the average particle diameter is an average particle diameter determined by a dynamic light scattering method, and specifically, an electrophoretic light scattering photometer ELS-800 (manufactured by Otsuka Electronics Co., Ltd.) or the like. Can be measured. Further, in this specification, the number average molecular weight can be measured by GPC (gel permeation chromatography), and can be calculated by a converted value based on polystyrene standards.

  Next, in the aqueous dispersion of the obtained fluoropolymer (a) particles, the radical polymerizable unsaturated monomer is seed-polymerized to the fluoropolymer (a) particles to form the fluororesin emulsion (A). Obtainable. As the seed polymerization method, for example, a conventionally known polymerization method described in JP-A-8-67795 can be used. More specifically, a radical polymerizable unsaturated monomer is added to an aqueous dispersion of the fluoropolymer (a) particles, and the radical polymerizable unsaturated monomer is used as a core of the fluoropolymer (a) particles (seed particles). This is a method in which a monomer is subjected to aqueous dispersion polymerization.

  The radically polymerizable unsaturated monomer means a monomer having at least one unsaturated bond such as a vinyl group in a molecule. Specific examples of the radically polymerizable unsaturated monomer include esters of (meth) acrylic acid. , Unsaturated carboxylic acids, hydroxyl group-containing alkyl vinyl ethers, carboxylic acid vinyl esters, α-olefins and the like. In addition, (meth) acrylic acid in this specification refers to acrylic acid or methacrylic acid.

  Preferable specific examples of the esters of (meth) acrylic acid include, from the viewpoint of good compatibility with the fluoropolymer (a), alkyl esters of (meth) acrylic acid having 1 to 10 carbon atoms, for example, ( Methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth) And cyclohexyl acrylate.

  Specific examples of the unsaturated carboxylic acids include acrylic acid, methacrylic acid, vinyl acetic acid, crotonic acid, cinnamic acid, 3-allyloxypropionic acid, 3- (2-allyloxyethoxycarbonyl) propionic acid, itaconic acid and itaconic acid. Acid monoester, maleic acid, maleic acid monoester, maleic anhydride, fumaric acid, fumaric acid monoester, vinyl phthalate, vinyl pyromellitate, undecylenic acid and the like. Among them, vinyl acetic acid, crotonic acid, itaconic acid, maleic acid, maleic acid monoester, fumaric acid, fumaric acid monoester, 3-allyloxypropionic acid, undecylenic acid having low homopolymerizability have low homopolymerizability. It is preferable because it is difficult to form a homopolymer and the introduction of a carboxyl group is easily controlled.

  Specific examples of the hydroxyl group-containing alkyl vinyl ethers include, for example, 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2-hydroxypropyl vinyl ether, 2-hydroxy-2-methylpropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxy- Examples include 2-methylbutyl vinyl ether, 5-hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, 2-hydroxyethyl allyl ether, 4-hydroxybutyl allyl ether, and glycerol monoallyl ether. Among these, 4-hydroxybutyl vinyl ether and 2-hydroxyethyl vinyl ether are preferred because of their excellent polymerization reactivity.

  Specific examples of vinyl carboxylate include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caproate, vinyl versatate, vinyl laurate, vinyl stearate, vinyl cyclohexyl carboxylate , Vinyl benzoate, vinyl para-t-butyl benzoate and the like. Examples of the α-olefin include ethylene, propylene, n-butene, isobutene and the like.

  The amount of the radical polymerizable unsaturated monomer used in the seed polymerization is preferably from 5 to 400 parts by mass, based on 100 parts by mass of the resin solid content of the fluoropolymer particles (A) as the seed particles. More preferably, it is 150 parts by mass.

  In the seed polymerization, a surfactant may be used as necessary. As the surfactant, the above-mentioned surfactant can be suitably used. When the surfactant is used, the amount used is preferably, for example, 0.01 to 5% by mass based on the total amount of water as a medium.

  The fluororesin emulsion (A) obtained by the above procedure preferably has an average particle size of 100 to 300 nm. Further, the number average molecular weight of the fluororesin emulsion (A) is preferably from 10,000 to 1,000,000.

  Commercial products can also be used as the fluororesin emulsion (A). Examples of commercially available products include Zeffle SE-310, SE-405, and SE-700 manufactured by Daikin Industries, Ltd.

Acrylic silicone resin emulsion (B)
The aqueous coating composition contains an acrylic silicone resin emulsion (B) in addition to the fluororesin emulsion (A). The acrylic silicone resin emulsion (B) can be prepared, for example, by polymerizing a monomer mixture containing an alkoxysilyl group-containing radically polymerizable unsaturated monomer and another radically polymerizable unsaturated monomer.

  The alkoxysilyl group-containing radical polymerizable unsaturated monomer is a radical polymerizable unsaturated monomer having an alkoxysilyl group. As the alkoxysilyl group, an alkoxysilyl group having 1 to 14 carbon atoms is preferable. One to three alkoxyl groups having 1 to 14 carbon atoms can be bonded to the silicon atom constituting the alkoxysilyl group having 1 to 14 carbon atoms. The alkoxyl group is easily hydrolyzed particularly in an acidic environment to form a silanol group. The dehydration of the silanol group forms a siloxane bond to crosslink or increase the molecular weight, so that the resulting coating film has improved film-forming properties, blocking resistance, and temperature resistance, and is particularly excellent. There is an advantage that high weather resistance and warm water resistance can be obtained.

  The above-mentioned alkoxysilyl group-containing radically polymerizable unsaturated monomer has a hydrocarbon group containing a polymerizable unsaturated bond such as a vinyl group, and at least one silicon atom constituting the alkoxysilyl group separately from the alkoxyl group. Combine. Due to having the unsaturated bond, the alkoxysilyl group-containing radically polymerizable unsaturated monomer can be subjected to addition polymerization, in addition to the effect of the siloxane bond, in addition to the film-forming properties of the resulting coating film, blocking resistance and Temperature change resistance can be improved.

  The alkoxysilyl group-containing radically polymerizable unsaturated monomer is not particularly limited as long as it is a radically polymerizable unsaturated monomer containing an alkoxysilyl group having 1 to 14 carbon atoms. For example, trimethoxysilylpropyl (meth) acrylate , Triethoxysilylpropyl (meth) acrylate, tributoxysilylpropyl (meth) acrylate, dimethoxymethylsilylpropyl (meth) acrylate, methoxydimethylsilylpropyl (meth) acrylate, vinyltrimethoxysilane, vinyltriethoxysilane , Vinyldimethoxymethylsilane, vinylmethoxydimethylsilane, vinyltris (β-methoxyethoxy) silane, and the like. These may be used alone or in combination of two or more.

  Of the alkoxysilyl group-containing radically polymerizable unsaturated monomers, trimethoxysilylpropyl (meth) acrylate, triethoxysilylpropyl (meth) acrylate, vinyltrimethoxysilane, and vinyltriethoxysilane are particularly preferable.

  The amount of the alkoxysilyl group-containing radically polymerizable unsaturated monomer contained in the monomer mixture is preferably in the range of 0.1 parts by mass and 3 parts by mass with respect to 100 parts by mass of the monomer mixture.

  The monomer mixture may further contain an alkoxysilane compound having 1 to 14 carbon atoms. When the alkoxysilane compound is contained, the obtained coating film can be provided with excellent weather resistance and water resistance.

  The alkoxysilane compound is not particularly limited as long as it is an alkoxysilane compound having an alkoxysilyl group having 1 to 14 carbon atoms. The alkoxysilyl group having 1 to 14 carbon atoms may be linear or branched. Good. Further, 1 to 4 alkoxysilyl groups may be bonded to silicon atoms constituting the alkoxysilane compound. In the present invention, the alkoxysilane compound does not have a polymerizable unsaturated bond such as a vinyl group in the compound, unlike the alkoxysilyl group-containing polymerizable monomer.

  The alkoxysilane compound is not particularly limited, and includes, for example, tetramethoxysilane, trimethoxymethylsilane, dimethoxydimethylsilane, methoxytrimethylsilane, tetraethoxysilane, triethoxyethylsilane, diethoxydiethylsilane, ethoxytriethylsilane, γ- Glycidoxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane and the like can be mentioned. These can be used alone or in combination of two or more. Of these, tetramethoxysilane, trimethoxymethylsilane, dimethoxydimethylsilane, methoxytrimethylsilane, and γ-glycidoxypropyltrimethoxysilane are preferred.

  The amount of the alkoxysilane compound is preferably in the range of 0.1 to 10 parts by mass based on 100 parts by mass of the monomer mixture.

  The monomer mixture contains another radically polymerizable unsaturated monomer in addition to the alkoxysilyl group-containing radically polymerizable unsaturated monomer.

The radical polymerizable unsaturated monomer is not particularly limited, for example,
Ethylenically unsaturated carboxylic acid monomers such as acrylic acid, methacrylic acid, maleic acid and itaconic acid;
Ethylene such as methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate An unsaturated carboxylic acid alkyl ester monomer;
Monoester monomers of ethylenically unsaturated dicarboxylic acids such as ethyl maleate, butyl maleate, ethyl itaconate and butyl itaconate;
Hydroxyl such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and a reaction product of 2-hydroxyethyl (meth) acrylate with ε-caprolactone Group-containing ethylenically unsaturated carboxylic acid alkyl ester monomers;
Ethylenically unsaturated carboxylic acid aminoalkyl ester monomers such as aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, and butylaminoethyl (meth) acrylate;
Ethylenically unsaturated carboxylic acid aminoalkylamide monomers such as aminoethyl (meth) acrylamide, dimethylaminomethyl (meth) acrylamide, methylaminopropyl (meth) acrylamide;
Other amide group-containing ethylenically unsaturated carboxylic acid monomers such as acrylamide, methacrylamide, N-methylolacrylamide, methoxybutylacrylamide, and diacetoneacrylamide;
Unsaturated fatty acid glycidyl ester monomers such as glycidyl acrylate and glycidyl methacrylate;
Vinyl cyanide monomers such as (meth) acrylonitrile and α-chloroacrylonitrile;
Vinyl esters of saturated aliphatic carboxylic acids such as vinyl acetate and vinyl propionate;
Styrene-based monomers such as styrene, α-methylstyrene and vinyltoluene;
And the like. These may be used alone or in combination of two or more.

  The monomer mixture contains an alkoxysilyl group-containing radically polymerizable unsaturated monomer and another radically polymerizable unsaturated monomer, wherein the other radically polymerizable unsaturated monomer is methyl methacrylate, n-butyl acrylate and acrylic acid 2. It preferably contains one or more selected from the group consisting of -ethylhexyl. More preferably, the other radically polymerizable unsaturated monomers include methyl methacrylate and n-butyl acrylate. In such an embodiment, the total amount of one or more selected from the group consisting of methyl methacrylate, n-butyl acrylate, and 2-ethylhexyl acrylate with respect to 100 parts by mass of the monomer mixture is 20 to 99. It is preferably in the range of 9 parts by mass, more preferably in the range of 40 to 99.9 parts by mass, still more preferably in the range of 50 to 99.9 parts by mass, and more preferably in the range of 68 to 99.9 parts by mass. It is particularly preferred that the amount be within the range of 9 parts by mass. Without being bound by theory, when the composition of the monomer mixture satisfies the above conditions, the compatibility in the fluororesin emulsion (A) and the acrylic silicone resin emulsion (B) becomes better, and as a result, a better It is believed that the haze value is achieved.

  When the other radically polymerizable unsaturated monomer contains one or more selected from the group consisting of methyl methacrylate, n-butyl acrylate and 2-ethylhexyl acrylate, for example, aromatic monomers such as styrene monomers The physical strength of the obtained acrylic silicone resin can be increased without using a group-containing monomer. Accordingly, there is an advantage that performance such as weather resistance can be improved by suppressing generation of radicals derived from an aromatic group.

  The other radically polymerizable unsaturated monomer may also include a substituted or unsubstituted cycloalkyl group-containing radically polymerizable unsaturated monomer. The cycloalkyl group-containing radically polymerizable unsaturated monomer is not particularly limited. For example, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate , Hydroxymethylcyclohexyl (meth) acrylate, cyclooctyl (meth) acrylate, cyclodecyl (meth) acrylate, cyclododecyl (meth) acrylate and the like. These can be used alone or in combination of two or more.

  The acrylic silicone resin emulsion (B) can be prepared by polymerizing the above monomer mixture in the presence of an emulsifier and a polymerization initiator as required, by a method known to those skilled in the art.

  As the emulsifier and the polymerization initiator, an emulsifier and a polymerization initiator known to those skilled in the art can be used. The emulsifier is not particularly limited, and may be a usual emulsifier, for example, a non-reactive emulsifier having no polymerizable unsaturated bond such as a vinyl group in the molecule, and / or a polymerizable polymer such as a vinyl group in the molecule. Reactive emulsifiers having unsaturated bonds can be used. The non-reactive emulsifier is not particularly limited, and examples thereof include sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, ammonium dodecyl sulfate, sodium diphenylether sulfonate, and polyoxyethylene alkyl ester. The reactive emulsifier is not particularly limited, and for example, Aqualon HS series such as Aqualon HS-10 (manufactured by Daiichi Kogyo Seiyaku), Aqualon RN series (manufactured by Daiichi Kogyo Seiyaku), Eleminor JS-2 (Sanyo Chemical Co., Ltd.) Industrial company), Latemul S-120, S-180A (manufactured by Kao Corporation) and the like. These can be used alone or in combination of two or more.

  The polymerization initiator generates radicals by heat or a reducing substance and causes addition polymerization of the monomer. A water-soluble polymerization initiator or an oil-soluble polymerization initiator can be used. The water-soluble polymerization initiator is not particularly limited, and examples thereof include persulfate initiators such as ammonium persulfate, sodium persulfate, and potassium persulfate, and inorganic initiators such as hydrogen peroxide. it can. These can be used alone or in combination of two or more. The oil-soluble polymerization initiator is not particularly limited, and examples thereof include benzoyl peroxide, t-butylperoxybenzoate, t-butyl hydroperoxide, t-butylperoxy (2-ethylhexanoate), and t-butyl. Organic peroxides such as peroxy-3,5,5-trimethylhexanoate, di-t-butyl peroxide, 2,2′-azobisisobutyronitrile, 2,2′-azobis-2,4 And azobis compounds such as -dimethylvaleronitrile, 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile) and 1,1'-azobis-cyclohexane-1-carbonitrile. These can be used alone or in combination of two or more.

  In the present invention, since the emulsion polymerization is mainly performed in an aqueous medium, it is preferable to use the water-soluble polymerization initiator. For example, ammonium persulfate can be suitably used. The water-soluble polymerization initiator or the oil-soluble polymerization initiator may be used in combination with a reducing agent such as sodium sulfite, ferrous chloride, ascorbate, and Rongalite, thereby accelerating the emulsion polymerization rate. In addition, it becomes easy to carry out emulsion polymerization at a low temperature.

  The amount of the emulsifier used is preferably a lower limit of 0.5 parts by mass and an upper limit of 10 parts by mass based on 100 parts by mass of the total amount of the monomer mixture. The amount of the polymerization initiator to be used is preferably a lower limit of 0.5 parts by mass and an upper limit of 10 parts by mass based on 100 parts by mass of the total amount of the monomer mixture.

  The acrylic silicone resin emulsion (B) may have a multilayer structure including a core and a shell. The acrylic silicone resin emulsion (B) having a multilayer structure can be prepared, for example, according to a known production method described in JP-A-2002-12816. When the acrylic silicone resin emulsion (B) has a multilayer structure composed of a core portion and a shell portion, preferred ranges of special values such as a preferred amount and ratio of a monomer mixture, a hydroxyl value, an SP value, and an average particle diameter are as follows: This is the same as the above or below preferred ranges.

  As the stirrer and polymerization conditions used for the polymerization of the acrylic silicone resin emulsion (B), a stirrer and conditions generally used by those skilled in the art can be used. For example, the polymerization temperature in the preparation of the acrylic silicone resin emulsion (B) is not particularly limited, and can be appropriately selected according to the type of the polymerization initiator and the like. The polymerization temperature is, for example, preferably from 40 to 120 ° C, and more preferably from 50 to 100 ° C. In the polymerization, the monomer mixture may be supplied continuously, sequentially, or stepwise. Further, an acrylic silicone resin emulsion having a core-shell structure composed of a core portion and a shell portion can be prepared by supplying two or more kinds of monomer mixtures in a stepwise manner.

  The acrylic silicone resin emulsion (B) has a solubility parameter (SP value) in the range of 9.5 to 10.9. The SP value is preferably in the range of 9.8 to 10.7, and more preferably in the range of 10.0 to 10.7. When the SP value of the acrylic silicone resin emulsion (B) is within the above range, there is an advantage that the affinity (compatibility) with the fluororesin emulsion (A) is improved and the appearance of the obtained coating film is improved.

  The SP value is an abbreviation of solubility parameter (solubility parameter) and is a measure of solubility. The higher the SP value, the higher the polarity, and the lower the SP value, the lower the polarity.

  For example, the SP value can be measured by the following method [Reference: SUH, CLARKE, J. et al. P. S. A-1, 5, 1671-1681 (1967)].

As a sample, 0.5 g of an organic solvent is weighed into a 100 ml beaker, and 10 ml of acetone is added using a whole pipette and dissolved with a magnetic stirrer. The poor solvent was dropped on this sample at a measurement temperature of 20 ° C. using a 50 ml burette, and the point at which turbidity occurred was defined as the dropping amount. As the poor solvent, a turbidity point is measured using ion-exchanged water as a high SP poor solvent and n-hexane as a low SP poor solvent. The SP value δ of the organic solvent is given by the following formula.
δ = (V _ml ^1/2 δ _ml + V _mh ¹ / _{2δ mh} ) / (V _ml ^1/2 + V _mh ^1/2 )
V _m = V ₁ V ₂ / (φ ₁ V ₂ + φ ₂ V ₁ )
δ _m = φ ₁ δ ₁ + φ ₂ δ ₂
Vi: molecular volume of solvent (ml / mol)
φi: volume fraction of each solvent at the turbid point δi: SP value of the solvent ml: low SP poor solvent mixed system hh: high SP poor solvent mixed system

  When the acrylic silicone resin emulsion (B) includes a plurality of types of acrylic silicone resin emulsions, the SP value of the acrylic silicone resin emulsion (B) is calculated using the SP value of each monomer. )) It can be determined by calculating an average value based on the mass ratio of solids in the component.

  The acrylic silicone resin emulsion (B) preferably has a hydroxyl value of 30 mgKOH / g or less. The hydroxyl value is more preferably 20 mgKOH / g or less, further preferably 10 mgKOH / g or less. When the hydroxyl value of the acrylic silicone resin emulsion (B) is within the above range, there are advantages such as that the obtained coating composition has good water resistance. In addition, in this specification, a hydroxyl value shows a solid content hydroxyl value and can be calculated based on the solid content hydroxyl value of the used monomer mixture.

  The acrylic silicone resin emulsion (B) preferably has a glass transition temperature (Tg) in the range of 10 to 25 ° C, more preferably in the range of 15 to 25 ° C.

  The glass transition temperature (Tg) is the mass fraction of each monomer constituting the fine particles (polymer) as a Tg (K: Kelvin) value of a homopolymer (homopolymer) derived from each monomer. It can be calculated as the reciprocal of the sum of each quotient obtained by dividing.

More specifically, in the present invention, the glass transition temperature (Tg) of the fine particles is calculated by the Fox equation (TG Fox; Bull. Am. Phys. Soc., 1 (3), 123 (1956)). can do.
For example, fine particles, when a polymer of a plurality of acrylic monomers represented by the following general formula _{1 / Tg = w 1 / Tg} 1 + w 2 / Tg 2 + ··· + w n / Tg n
Is defined as the Tg of the fine particles.
Tg _a: glass transition temperature of the homopolymer of monomer _A (K), W _a: weight fraction of monomer A tg _b: glass transition temperature of the homopolymer of monomer B (K), W _b: mass fraction of monomer B Tg _n : glass transition temperature (K) of homopolymer of monomer N, W _n : mass fraction of monomer N (W _a + W _b +... + W _n = 1)

If the acrylic silicone resin emulsion (B) has a core-shell structure, the glass transition temperature of the shell portion (Tg _s)> is preferably from the glass transition temperature of the core (Tg _c), the glass transition temperature of the core (Tg _c ) is at 0 ℃ or less, the glass transition temperature of the shell (Tg _s) is more preferably at 30 ° C. or higher. In the case where the acrylic silicone resin emulsion (B) has a core-shell structure, the “glass transition temperature (Tg) of the acrylic silicone resin emulsion (B)” indicates the mass fraction of the constituent core and shell, and the core and shell, respectively. It can be calculated as the reciprocal of the sum of each quotient obtained by dividing by the Tg (K: Kelvin) value.

  The acrylic silicone resin emulsion (B) preferably has an average particle diameter in the range of 80 to 200 nm, more preferably 100 to 150 nm. When the average particle diameter of the acrylic silicone resin emulsion (B) is within the above range, there is an advantage that the obtained coating film can sufficiently secure sufficient water resistance.

Aqueous paint composition and coating film An aqueous paint composition can be prepared using the above-mentioned fluororesin emulsion (A) and acrylic silicone resin emulsion (B). The aqueous coating composition may be, for example, a fluororesin emulsion (A), an acrylic silicone resin emulsion (B), and, if necessary, pigments, additives, solvents, and the like usually used in the art. It can be prepared by mixing according to a given method.

  When the pigment is contained, the pigment is not particularly limited, and examples thereof include extender pigments, inorganic coloring pigments, and organic coloring pigments. When a pigment is used, it is preferable to use the pigment within a range where the pigment mass concentration (PWC) with respect to the resin solid content of the coating composition is 5 to 60% by mass.

  In the preparation of the water-based coating composition, additives usually used, for example, viscosity modifier, surface modifier, filler, dispersant, ultraviolet absorber, light stabilizer, antioxidant, antifreeze, antialgal agent , An antifoaming agent, a film-forming aid, a preservative, a fungicide, a pH adjuster, and the like. The method for preparing the aqueous coating composition is not particularly limited, and can be prepared by a commonly used method such as stirring each component described above using a stirrer or the like.

  The solid content mass ratio of the fluororesin emulsion (A) and the acrylic silicone resin emulsion (B) contained in the aqueous coating composition is (A) :( B) = 20: 80 to 90:10. It is more preferable that (A) :( B) = 50: 50 to 80:20. When the solid content mass ratio (A) :( B) is within the above range, there is an advantage that an aqueous coating composition having a good balance between weather resistance and water resistance can be obtained.

  Furthermore, regarding the fluororesin emulsion (A) and the acrylic silicone resin emulsion (B) contained in the aqueous coating composition, the solid content ratio of the fluororesin emulsion (A) and the acrylic silicone resin emulsion (B) is 1: 1. It is more preferable that the haze value of a dried coating film (film thickness: 50 μm) obtained by applying the above mixture so that the dry film thickness becomes 50 μm is 4.10 or less. When the haze value of the dried coating film of the mixture of the fluororesin emulsion (A) and the acrylic silicone resin emulsion (B) at a solid content of 1: 1 is within the above range, the fluororesin emulsion (A) and the acrylic silicone resin It means that the affinity of the emulsion (B) is high. By using such a fluororesin emulsion (A) and an acrylic silicone resin emulsion (B), there is an advantage that an aqueous coating composition having good weather resistance and good water resistance can be obtained. .

  The aqueous coating composition thus prepared can be applied to various objects to be coated. As the object to be coated, for example, a building material used for a wall surface or a roof such as an inner wall or an outer wall of a building such as a house or a building is preferable. Therefore, the above-mentioned aqueous coating composition can be used as an aqueous coating composition for building material coating or an aqueous coating composition for building coating. The aqueous coating composition can be used, for example, as an aqueous clear coating composition for building material coating or an aqueous clear coating composition for building coating.

  The building material suitable as the object to be coated with the aqueous coating composition is not particularly limited, and examples thereof include inorganic material building materials, woody building materials, metal building materials, and plastic building materials.

Examples of the inorganic material building materials include ceramic building materials and glass base materials described in JIS A 5422, JIS A 5430, etc., and examples thereof include a silica plate, a pulp cement plate, a slag gypsum plate, and magnesium carbonate. Examples include a board, an asbestos perlite board, a wood chip cement board, a hard wood cement board, a concrete board, a lightweight cellular concrete board and the like.
Examples of the wooden building materials include lumber, laminated wood, plywood, particle board, fiber board, improved wood, chemical treated wood, floorboard, and the like.
Examples of the plastic building material include an acrylic plate, a polyvinyl chloride plate, a polycarbonate plate, an ABS plate, a polyethylene terephthalate plate, and a polyolefin plate.
Examples of the metal building material include an aluminum plate, an iron plate, a galvanized steel plate, an aluminum galvanized steel plate, a stainless steel plate, and a tin plate.

  The object to be coated may be previously coated with a sealer composition, an undercoat composition, or the like, if necessary. Examples of the undercoat composition include an aqueous undercoat composition containing a pigment (for example, various color pigments). The water-based coating composition also has an advantage that it adheres well to coating films of various undercoat coating compositions containing a color pigment.

  The method of applying the aqueous coating composition is not particularly limited, and examples thereof include commonly used coatings such as dipping, brushing, a roller, a roll coater, an air spray, an airless spray, a curtain flow coater, a roller curtain coater, and a die coater. Methods and the like can be mentioned. These can be appropriately selected according to the type of building material and the like. The aqueous coating composition is preferably coated so as to have a dry film thickness of 30 μm to 1 mm, and more preferably 50 to 500 μm.

  After applying the aqueous coating composition, a drying step may be performed as necessary. Drying conditions can be appropriately selected depending on the shape and size of the article to be coated. Specific examples of drying conditions include, for example, heating at a temperature of 50 to 130 ° C. for 1 to 60 minutes.

  The aqueous coating composition contains a specific fluororesin emulsion (A) and an acrylic silicone resin emulsion (B). A coating film formed by using the above-mentioned aqueous coating composition has an advantage that, in addition to being excellent in weather resistance, it also has excellent blocking resistance and water resistance. The aqueous coating composition can be suitably used as an aqueous coating composition for building material coating or an aqueous coating composition for building coating, for example, an aqueous clear coating composition for building material coating, or an aqueous clear composition for building coating. It can be suitably used as a coating composition.

  The present invention will be described more specifically with reference to the following examples, but the present invention is not limited thereto. In Examples, "parts" and "%" are based on mass unless otherwise specified.

Production Example 1-1 Production of Fluororesin Emulsion (A-1)
Step (I)
In a 2 L stainless steel autoclave, 500 parts by mass of ion-exchanged water, 2.2 parts by mass of a 50% by mass aqueous solution of ammonium perfluorohexanoate, ammonium polyoxyethylene nonylpropenyl phenyl ether sulfate (Aqualon HS-10, Daiichi Kogyo Seiyaku) 0.789 parts by mass of a 38% by mass aqueous solution (manufactured by K.K.), the system was sufficiently purged with nitrogen gas, and the pressure was reduced. Subsequently, vinylidene fluoride (VdF) / tetrafluoroethylene (TFE) / chlorotrifluoroethylene (CTFE) (= 72.2 / V) so that the pressure in the polymerization tank becomes 0.75 to 0.8 MPa. (16.0 / 11.8 mol%) The mixed monomer was injected under pressure and the temperature was raised to 70 ° C.
Next, a polymerization initiator solution in which 1.00 part by mass of ammonium persulfate was dissolved in 4 parts by mass of ion-exchanged water and 0.75 part by mass of ethyl acetate were press-fitted with nitrogen gas, and the reaction was started while stirring at 600 rpm. At the time when the internal pressure starts to decrease with the progress of polymerization, the VdF / TFE / CTFE mixed monomer (= 72.2 / 16.0 / 11.8 mol%) is converted to an internal pressure of 0.75 to 0.8 MPa. Supplied to maintain. After 7 hours and 33 minutes from the start of the polymerization, unreacted monomers were released, and the autoclave was cooled to obtain an aqueous dispersion of a fluoropolymer (solid content: 46.1% by mass, average particle size: 112 nm). Was. The particle diameter was measured using an electrophoretic light scattering photometer ELS-800 (manufactured by Otsuka Electronics Co., Ltd.).
This aqueous dispersion was frozen at −10 ° C. for 24 hours to perform coagulation. The obtained coagulated product was washed with water and dried to obtain fluoropolymer (a-1) particles.

Process (II)
The fluoropolymer (a-1) particles obtained in the step (I) are dispersed in ion-exchanged water, and an aqueous dispersion of the fluoropolymer (a-1) (solid content: 38.4% by mass) ) Was prepared. 43.94 parts by mass of polyoxyethylene nonylpropenyl phenyl ether ammonium sulfate (Aqualon HS-10, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was added to 1,783.8 parts by mass of the obtained aqueous dispersion of the fluoropolymer (a-1). Was added and mixed well to prepare an emulsion of the fluoropolymer (a-1).
Next, in a stainless steel container, 513.1 parts by mass of methyl methacrylate (MMA), 162.4 parts by mass of butyl acrylate (BA), 6.8 parts by mass of acrylic acid (AA), 2.1 parts by mass of mercaptan, ion exchange 159.0 parts by mass of water was added and mixed with a disper to prepare a preliminary emulsion. The whole amount of the pre-emulsion was gradually added to the emulsion of the fluoropolymer (a-1) and mixed well with a disper. Then, polyethylene glycol monomethyl ether methacrylate (RMA-450) was further used as a surfactant. , Nippon Emulsifier Co., Ltd.) and 95.4 parts by mass of a 50% aqueous solution of methacryloyloxy polyoxyalkylene sulfate sodium salt (Eleminol RS-3000, manufactured by Sanyo Chemical Industries, Ltd.) were added and mixed with a disper. .
The internal temperature of the reaction vessel was raised to 75 ° C., and polymerization was promoted while adding 75.2 parts by mass of a 1% by mass aqueous solution of ammonium persulfate in four portions every 40 minutes. Two hours after the start of the polymerization, the reaction solution was cooled to room temperature to terminate the reaction, and 2,857.6 parts by mass of a fluororesin emulsion (A-1) (solid content: 51.7% by mass, average particle size: 160 nm) ) Got.

Production Examples 1-2, 1-3 Production of Fluororesin Emulsions (A-2) and (A-3) Production Example 1-1 except that the type and amount of the radical polymerizable unsaturated monomer were changed according to the following table. In the same manner as in the above, fluororesin emulsions (A-2) and (A-3) were obtained.

Production Example 2-1 Production of Acrylic Silicone Resin Emulsion (B-1) In a stainless steel container, 42.9 parts by mass of methyl methacrylate, 9.6 parts by mass of cyclohexyl methacrylate, 33.7 parts by mass of butyl acrylate, butyl methacrylate After stirring and mixing 10.5 parts by mass, 1.8 parts by mass of methacrylic acid and 1.5 parts by mass of 3-trimethoxysilylpropyl methacrylate, ammonium sulfosuccinate diester (Latemul S-180A, manufactured by Kao Corporation) 5 as an emulsifier 0.0 parts by mass and 20.3 parts by mass of water were added, and the mixture was stirred at room temperature for 15 minutes using a homomixer to obtain an emulsified mixture before the reaction.
94.7 parts by mass of water is charged into a reaction vessel equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer, and the temperature in the reaction vessel is raised to 80 ° C., and then the above-mentioned emulsified mixture before reaction is 125.3 masses , And 13 parts by mass of a 1.5% by mass aqueous solution of ammonium persulfate as a reaction initiator were simultaneously dropped over 2 hours from separate dropping funnels. After completion of the dropwise addition, the temperature in the reaction vessel was maintained at 80 ° C. for 1 hour, and then cooled to 30 ° C., and 233.0 parts by mass of an acrylic silicone resin emulsion (B-1) (solid content: 45.0 parts by mass) %, Particle diameter: 132 nm).
The particle size of the obtained acrylic silicone resin emulsion was measured using an electrophoretic light scattering photometer ELS-800 (manufactured by Otsuka Electronics Co., Ltd.).

Production Examples 2-2 to 2-5 and 2-7 to 2-8 Production of acrylic silicone resin emulsions (B-2) to (B-5) and (B-7) to (B-8) Acrylic silicone resin emulsions (B-2) to (B-5) and (B-7) to (B-8) were obtained in the same manner as in Production Example 2-1 except that the type and amount of the monomer were changed. Was.

Production Example 2-7 Production of Core-Shell Type Acrylic Silicone Resin Emulsion (B-6) In a stainless steel container, 17.5 parts by mass of methyl methacrylate, 9.6 parts by mass of cyclohexyl methacrylate, 29.2 parts by mass of butyl acrylate, methacryl After stirring and mixing 1.0 parts by mass of an acid and 1.5 parts by mass of 3-trimethoxysilylpropyl methacrylate, 2.5 parts by mass of sulfosuccinic acid diester ammonium salt (Latemul S-180A, manufactured by Kao Corporation) as an emulsifier and water 30 The mixture was stirred at room temperature for 15 minutes using a homomixer to obtain a first pre-reaction emulsified mixture.
61.1 parts by mass of water was charged into a reaction vessel equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer, and the temperature in the reaction vessel was raised to 80 ° C. 8 parts by mass and 5.5 parts by mass of a 1.5% by mass aqueous solution of ammonium persulfate as a reaction initiator were simultaneously added dropwise from separate dropping funnels over 2 hours. After the completion of the dropwise addition, the temperature in the reaction vessel was maintained at 80 ° C. for 30 minutes to obtain an acrylic silicone resin emulsion.
In a separate container, 25.4 parts by mass of methyl methacrylate, 4.5 parts by mass of butyl acrylate, 10.5 parts by mass of butyl methacrylate, and 0.8 parts by mass of methacrylic acid are stirred and mixed, and then ammonium sulfosuccinate diester is used as an emulsifier. 2.5 parts by mass of salt (Latemul S-180A, manufactured by Kao Corporation) and 25.0 parts by mass of water were added, and the mixture was stirred at room temperature for 15 minutes using a homomixer to obtain an emulsified mixture before the second reaction.
Into a container containing the acrylic silicone resin emulsion obtained earlier, 68.7 parts by mass of the emulsified mixture before the second reaction and 5.5 parts by mass of a 1.5% by mass aqueous solution of ammonium persulfate as a reaction initiator were separately dropped into a dropping funnel. Then, the mixture was simultaneously added dropwise over 2 hours. After the completion of the dropwise addition, the temperature in the reaction vessel was maintained at 80 ° C. for 1 hour, and then cooled to 30 ° C., and 232.6 parts by mass of a core-shell type acrylic silicone resin emulsion (B-6) (solid content: 45.50 parts). 0 mass%, particle diameter: 136 nm).

Production Example 3 Production of Acrylic Resin Emulsion (C) An acrylic resin emulsion (C) was obtained in the same manner as in Production Example 2-1 except that the type and amount of the monomer were changed according to the following table.

Example 1 Production of aqueous coating composition (1) Fluororesin emulsion (A-1) (solid content: 51.7% by mass) 46.0 parts by mass (solids 23.8 parts by mass), acrylic silicone resin emulsion (B-1) (solid content concentration: 45.0% by mass) 21.9 parts by mass (solids content 9.9 parts by mass), diethylene glycol dibutyl ether (DBDG, film forming aid) 4.6 parts by mass, and water 16 Then, 0.8 parts by mass of Primal ASE 60 (manufactured by Dow Chemical Company, thickener) was added, followed by stirring and mixing with a disper to obtain an aqueous coating composition (1).
The viscosity of the obtained aqueous coating composition was measured at 25 ° C. using a Stormer viscometer KU-2 (manufactured by BROOKFIELD) and found to be 67 KU.

Examples 2 to 12 and Comparative Examples 1 to 5 Production of aqueous coating compositions (2) to (17) According to the following table, a fluororesin emulsion (A), an acrylic silicone resin emulsion (B) and an acrylic resin emulsion (C) were prepared . Coating compositions (2) to (17) were obtained in the same manner as in Example 1 except that the type and amount were changed.

  The following evaluations were performed using the aqueous coating compositions obtained from Examples and Comparative Examples. The evaluation results are shown in the following table. In Comparative Example 5, (B) should be read as (C).

Preparation of a test plate Spray-coating on a siding board with AudePower 390 Spray (Nippon Paint Industrial Coatings Co., Ltd.), which is an aqueous primer coating composition containing a coloring pigment, so that the dry film thickness becomes 50 μm. It was dried at 100 ° C. for 3 minutes in a jet drier (wind speed: 10 m / s).
Next, the aqueous coating compositions obtained in Examples and Comparative Examples were spray-coated so that the dry film thickness became 30 μm, and dried at 100 ° C. for 10 minutes by a jet drier (wind speed: 10 m / s). A test plate was obtained.

The fluororesin emulsion (A) and the acrylic silicone resin emulsion (B) were mixed with a disper so that the solid content mass ratio was 1: 1 to obtain an emulsion mixture. The obtained emulsion mixture is applied on a glass plate using a doctor blade (6 mil) so as to have a dry film thickness of 50 μm, and dried at 100 ° C. for 10 minutes by a jet drier (wind speed: 10 m / s). Then, a test plate was obtained.
Using a haze meter NDH-2000 (manufactured by Nippon Denshoku Industries Co., Ltd.) as a test machine, the haze value of the obtained test plate was measured based on an unpainted glass plate.
The measured haze value was evaluated according to the following criteria. The smaller the haze value, the smaller the turbidity of the coating film and the better the compatibility.

：: The haze value was smaller than 4.10.
C: The haze value was 4.10 or more and 4.50 or less.
X: The haze value exceeded 4.50.

Evaluation of Blocking Resistance The obtained test plate was evaluated for blocking resistance using a blocking tester (manufactured by Kami Kiko Co., Ltd.) according to the following procedure.
Two coated test surfaces were placed on top of each other, a test was conducted at a plate temperature of 50 ° C. and a load of 3 kg / cm ² for 10 minutes, and the appearance of the coating film when the test plates were separated was visually observed. The evaluation was based on criteria.

：: There was no change in the coating film surface.
Δ: Damage was observed in a part of the coating film.
×: Damage was observed on the entire surface of the coating film.

Weather resistance evaluation (exposure test)
The obtained test plate was subjected to a two-year exposure test at Miyakojima Weathering Center, Nippon Paint Holdings, based on a direct exposure test (based on JIS Z 2381 General rules for outdoor exposure test method and JIS K 5600-7-6 etc.). . The 60 ° gloss value of the coating film after 2 years was measured with a gloss meter GN-268Plus (manufactured by Konica Minolta), and the change rate (gloss retention rate) with respect to the 60 ° gloss value before installation was calculated. Was evaluated. In addition, the location of the exposure field is as follows.
Exposure location: 3742 Karima, Hirara, Miyakojima City, Okinawa Prefecture (24 ° 51′N)

：: The gloss retention was 80% or more.
Δ: The gloss retention was 60% or more and less than 80%.
X: The gloss retention was less than 60%.

Weather resistance evaluation (accelerated weather resistance test)
The obtained test plate was subjected to an accelerated weathering test for 6,000 hours using a sunshine weatherometer S80 (sunshine carbon arc type accelerated weathering tester, manufactured by Suga Test Instruments Co., Ltd.) (operating conditions: JIS B). 7753). The 60 ° gloss value of the coating film after the test for 6,000 hours was measured with a gloss meter GN-268Plus (manufactured by Konica Minolta), and the rate of change (gloss retention) with respect to the 60 ° gloss value before the test was calculated. Evaluation was made according to the following criteria.

：: The gloss retention was 80% or more.
X: The gloss retention was less than 80%.

Hot water resistance evaluation (hot water immersion test)
After immersing the test plate in hot water at 60 ° C. for 10 days, the test plate was taken out, and the appearance and color difference (ΔL value) of the coating film were evaluated according to the following methods and criteria.
The hue (L value) of the coating surface before and after the test was measured with a colorimeter CR-300 (manufactured by Konica Minolta), and the L value (L0) of the coating film before the test and the hue (L0) after the test were measured. It was determined by calculating the difference (ΔL value (L1−L0)) from the coating film L value (L1). The smaller the ΔL value, the smaller the water absorption whitening of the coating film.

：: ΔL value was 2 or less.
Δ: ΔL value was greater than 2 and less than 3.
×: ΔL value was 3 or more.

All of the aqueous coating compositions of the examples were good in compatibility (haze value) evaluation, blocking resistance evaluation, weather resistance evaluation, and water resistance evaluation.
Comparative Examples 1 and 2 are examples in which the SP value of the acrylic silicone resin emulsion (B) is not in the range of 9.5 to 10.9. In each of these examples, it was confirmed that the water resistance was poor.
Comparative Example 3 is an example not including the fluororesin emulsion (A). In this example, it was confirmed that the weather resistance was poor.
Comparative Example 4 is an example not including the acrylic silicone resin emulsion (B). In this example, it was confirmed that the water resistance was poor.
Comparative Example 5 is an example in which an acrylic resin emulsion was used instead of the acrylic silicone resin emulsion (B). In this example, it was confirmed that the weather resistance was poor.

  The aqueous coating composition contains a specific fluororesin emulsion (A) and an acrylic silicone resin emulsion (B). A coating film formed by using the above-mentioned aqueous coating composition has an advantage that, in addition to being excellent in weather resistance, it also has excellent blocking resistance and water resistance. Since the aqueous coating composition further contains a fluorine-containing seed polymerization emulsion as the fluororesin emulsion (A), it is inexpensive despite the high concentration of fluorine atoms, and has the advantage of reducing production costs.

Claims (9)

A fluororesin emulsion (A) and an acrylic silicone resin emulsion (B),
An aqueous coating composition comprising:
The fluororesin emulsion (A) is a fluorinated seed polymerization emulsion, and the SP value of the acrylic silicone resin emulsion (B) is in the range of 9.5 to 10.9.
Aqueous coating composition.   The aqueous coating composition according to claim 1, wherein the acrylic silicone resin emulsion (B) has a hydroxyl value of 30 mgKOH / g or less. The acrylic silicone resin emulsion (B) is an emulsion polymer of a monomer mixture,
The monomer mixture contains an alkoxysilyl group-containing radically polymerizable unsaturated monomer,
The aqueous coating composition according to claim 1. The monomer mixture further comprises one or more selected from the group consisting of methyl methacrylate, n-butyl acrylate and 2-ethylhexyl acrylate,
The total amount of one or more selected from the group consisting of methyl methacrylate, n-butyl acrylate and 2-ethylhexyl acrylate with respect to 100 parts by mass of the monomer mixture is within the range of 20 to 99.9 parts by mass. Is,
The aqueous coating composition according to claim 1.   The aqueous coating composition according to any one of claims 1 to 4, wherein the fluororesin emulsion (A) is an emulsion of a seed polymer of a radically polymerizable unsaturated monomer using fluoropolymer particles as seeds.   The solid content mass ratio of the fluororesin emulsion (A) and the acrylic silicone resin emulsion (B) contained in the aqueous coating composition is (A) :( B) = 20: 80 to 90:10. The aqueous coating composition according to any one of claims 1 to 5.   The haze value of a coating film having a dry coating film thickness of 50 μm of a mixture of a fluororesin emulsion (A) and an acrylic silicone resin emulsion (B) having a solid content mass ratio of 50:50 is 4.10 or less. The aqueous coating composition according to any one of claims 1 to 6.   The aqueous coating composition according to any one of claims 1 to 7, which is an aqueous coating composition for building material coating or building coating. A method for producing a water-based coating composition according to any one of claims 1 to 8, comprising the following steps:
A step of subjecting a radical polymerizable unsaturated monomer to seed polymerization of a fluoropolymer particle in an aqueous dispersion of fluoropolymer particles to obtain a fluororesin emulsion (A),
A step of emulsion-polymerizing a monomer mixture containing an alkoxysilyl group-containing radical polymerizable unsaturated monomer to obtain an acrylic silicone resin emulsion (B), and mixing the fluororesin emulsion (A) and the acrylic silicone resin emulsion (B) A step of obtaining an aqueous coating composition,
Including,
A method for producing an aqueous coating composition.