JP4690227B2 - Aqueous dispersion and paint using the same - Google Patents

Description

  The present invention relates to an aqueous dispersion using an organosiloxane or a hydrolyzate thereof and a paint using the same.

  In recent years, there has been a strong demand for pollution-free paints for environmental protection and safety and health, and conventional solvent-based paints are being made water-based. For example, water-based (meth) acrylic emulsion type paints are characterized by easy handling, no solvent odor, no risk of flammable explosion, direct application on wet surfaces, and relatively low cost. However, water-based (meth) acrylic emulsion-type paints may have problems such as insufficient weather resistance, poor gloss compared to solvent-type paints, and relatively slow drying depending on the application. is doing.

  In addition, solvent-type silicone acrylic copolymer resin paints are widely used because they have excellent weather resistance, water repellency, and stain resistance following fluororesin paints. Yes. However, when it becomes aqueous, the alkoxysilyl group contained in the resin is hydrolyzed to form a silanol group, and this generated silanol group may condense with time, resulting in an increase in the viscosity of the paint or gelation. There is a problem that there is.

  In order to solve these problems, a method of obtaining a stable emulsion by preparing an emulsion of a polymer having no alkoxysilyl group and then adding an alkoxysilane compound and hydrolyzing it (Patent Document 1) , A method of preparing an emulsion of a polymer having no alkoxysilyl group, hydrolyzing it by adding an alkoxysilane compound and further subjecting it to a condensation reaction (Patent Document 2), polymerizable double bond An aqueous emulsion (Patent Document 3) obtained by simultaneously carrying out radical copolymerization of a reactive silane monomer containing ethylenic unsaturated monomer and cationic polymerization of a linear siloxane precursor monomer has been proposed. All emulsions have the problem of poor stability.

  Furthermore, in the presence of an alkoxysilane that does not contain a polymerizable double bond, polymerization and condensation of a reactive silane monomer containing a polymerizable double bond and an ethylenically unsaturated monomer are simultaneously performed, and the resulting emulsion is organically mixed. Although it has been proposed to produce a microgel dispersion by phase inversion with a solvent (Patent Document 4), it goes against the pollution-free coating, that is, the transition from a solvent system to an aqueous system, and the process is complicated. It is insufficient in that there is.

  In addition, an emulsion obtained by simultaneously copolymerizing an alkoxysilane containing no polymerizable double bond, a reactive silane monomer having a polymerizable double bond, an ethylenically unsaturated monomer, and an ethylenically unsaturated monomer having a carboxyl group Has been proposed to prepare an emulsion by copolymerizing an ethylenically unsaturated monomer and an ethylenically unsaturated monomer having a carboxyl group (Patent Document 5). In the case of an emulsion prepared by this method In addition, the production method is complicated and the emulsion is insufficiently stable, the film-forming property is not good, a large amount of film-forming auxiliary is required, and thus the stain resistance of the coating film is lowered. is there.

  In addition, an emulsion obtained by copolymerizing an ethylenically unsaturated monomer and an ethylenically unsaturated monomer having a carboxyl group is used as a seed particle to react with an alkoxysilane that does not contain a polymerizable double bond and a polymerizable double bond. A method of preparing an emulsion by simultaneously copolymerizing a functional silane monomer, an ethylenically unsaturated monomer and an ethylenically unsaturated monomer having a carboxyl group (Patent Document 6) has been proposed. The emulsion obtained by this method is insufficient in stability and is insufficient in that the film-forming property is not good, so that a large amount of film-forming aid is required, and therefore the stain resistance of the coating film is reduced. .

  In addition, a method of adding colloidal silica particles to make the surface of the coating film hydrophilic and improving the stain resistance (Patent Document 7) has also been proposed. However, the glossiness of the film deteriorates, the coating film becomes hard, and the frost resistance is deteriorated.

JP-A-4-173807 JP-A-4-57868 JP-A-2-67324 JP-A-60-181173 Japanese Patent Laid-Open No. 5-93071 JP-A-4-175343 Japanese Patent Application Laid-Open No. 11-116885

  The object of the present invention is to solve the above-mentioned problems and to obtain an aqueous dispersion exhibiting excellent stain resistance and frost damage resistance and having high emulsion stability, and a paint using the same.

  This invention is a dispersion containing an organosiloxane or a hydrolyzate thereof (A) and a (meth) acrylic polymer (B) having a glass transition temperature of −30 to 70 ° C. By using an aqueous dispersion having an ionic component (C), the above problems have been solved.

  The aqueous dispersion according to the present invention harmonizes the light resistance by the component (A), the frost damage resistance by the component (B) and the stain resistance improvement by the component (C) at a high level, and has emulsion stability. Good and glossy coating film can be provided.

Embodiments of the present invention will be described below.
The aqueous dispersion according to the present invention comprises an organosiloxane or a hydrolyzate thereof (hereinafter referred to as “component (A)”) and a predetermined (meth) acrylic polymer (hereinafter referred to as “component (B)”. A dispersion containing a zwitterionic component (hereinafter referred to as “component (C)”).

((A) component)
The organosiloxane constituting the component (A) or a hydrolyzate thereof is a compound used for the purpose of improving weather resistance. Examples of the organosiloxane or a hydrolyzate thereof include alkyl alkoxysilanes, alkylalkoxysilanes partially hydrolyzed and condensed (hereinafter collectively referred to as “alkylalkoxysilanes”), and the like. Examples of such alkylalkoxysilanes include trialkoxysilane, trimethylethoxysilane, and dimethylethoxysilane as monoalkoxysilane, and dimethyldimethoxysilane, dimethyldiethoxysilane, and methylphenyldimethoxysilane as dialkoxysilanes. Examples of trialkoxysilanes include methyltrimethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, and i-propyltrimethoxysilane. These alkoxysilanes may further have a substituent such as an amino group or a mercapto group.

  The organosiloxane hydrolyzate can be obtained by hydrolyzing the organosiloxane with water or water containing acid / alkali or the like.

((B) component)
The (meth) acrylic polymer constituting the component (B) is a resin serving as a base material for the aqueous dispersion according to the present invention, and is a monomer homopolymer containing a (meth) acrylic monomer. Or a copolymer. In this specification, “(meth) acryl” means “acryl or methacryl”.

  Examples of the (meth) acrylic polymer include (meth) acrylic resin, (meth) acrylic / styrene copolymer resin, vinyl acetate / (meth) acrylic copolymer, vinyl chloride / (meth) acrylic copolymer resin And silicone-containing (meth) acrylic resins.

  Monomers constituting the (meth) acrylic polymer include (meth) acrylic acid ester monomers, styrene or derivatives thereof, (meth) acrylonitrile, vinyl acetate, other vinyl monomers, butadiene, chloroprene, isoprene. And diene monomers. As these monomers, only (meth) acrylic monomers may be used, or one or more of other comonomers may be selected and used. Moreover, when emulsion-polymerizing these monomers, in order to stabilize the produced | generated emulsion particle | grains, it is preferable to copolymerize using the radically polymerizable monomer which has a hydrophilic group.

  Preferred examples of the (meth) acrylic acid ester monomer include (meth) acrylic acid (cyclo) alkyl esters having 1 to 8 carbon atoms in the alkyl group. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, (meth) acrylic Examples include 2-ethylhexyl acid, n-octyl (meth) acrylate, and cyclohexyl (meth) acrylate.

  Specific examples of the styrene or derivatives thereof include styrene, α-methylstyrene, vinyltoluene and the like.

  Specific examples of the other vinyl monomers include (meth) acrylonitrile, vinyl acetate, vinyl propionate, vinyl versatate, vinyl chloride and the like.

  The silicone-containing (meth) acrylic resin is obtained by emulsion polymerization of (meth) acrylic monomers such as (meth) acrylic acid alkyl esters in the presence of alkylalkoxysilanes or partial hydrolysates thereof. Manufactured by the method.

  Examples of the radical polymerizable monomer having a hydrophilic group include anionic, cationic, and nonionic monomers.

  Examples of the anionic monomer include a carboxyl group-containing monomer having a carboxyl group in the molecule, a sulfone group-containing monomer having a sulfone group in the molecule, and a phosphate group-containing monomer having a phosphate group in the molecule. These anionic monomers can also be used as salts of alkali metals such as ammonia, organic amines such as trimethylamine and monoethanolamine, and sodium and potassium.

  Examples of the carboxyl group-containing monomer include maleic acid, fumaric acid, crotonic acid, itaconic acid, acrylic acid, and methacrylic acid. Examples of the sulfone group-containing monomer include vinyl sulfonic acid, allyl sulfone test, (meth) acryl sulfonic acid, styrene sulfonic acid, (meth) acrylic acid 2-ethyl sulfonic acid, (meth) acrylamide 2-methyl sulfonic acid, and the like. Can be given. Furthermore, examples of the phosphate group-containing monomer include (meth) acrylic acid 2-hydroxyethyl phosphate ester.

  Next, examples of the cationic monomer include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, (meth) acrylamide dimethylaminopropyl, (meth) acrylamidopropyltrimethylammonium chloride, diallyldimethylammonium chloride. , P-vinylbenzylammonium chloride and the like.

  Examples of the nonionic monomer include (meth) acrylamide, N-methylol (meth) acrylamide, N, N-dimethyl (meth) acrylamide, (meth) acryloylmorpholine, diacetone (meth) acrylamide, vinyl pyrrolidone, vinyl oxazolidone, (meth) ) Hydroxyethyl acrylate, hydroxypropyl (meth) acrylate, and the like.

  If the amount of the radically polymerizable monomer having a hydrophilic group is too small, the stability of the emulsion is lowered, and if too large, the water resistance of the film after drying is deteriorated. About 5 to 10% by weight, preferably about 1 to 5% by weight.

  Furthermore, an amphoteric monomer having a polymerizable double bond can be used as the radical polymerizable monomer having a hydrophilic group. By using the zwitterionic monomer having a polymerizable double bond, the feature of improving the stain resistance can be exhibited. In addition, the structural unit which consists of the said amphoteric monomer in the (meth) acrylic-type polymer using this amphoteric monomer corresponds to the (C2) component of the (C) component mentioned later.

  Examples of the zwitterionic group possessed by the zwitterionic monomer having a polymerizable double bond include betaine-based zwitterionic groups. The betaine zwitterionic group refers to a group represented by the following chemical formula (1).

^{-R 1 -N + (R 2)} (R 3) -R 4 -X - (1)
In the above formula (1), R ¹ and R ⁴ each independently represent an alkylene group having 1 to 4 carbon atoms, and R ² and R ³ each independently represent an alkyl group having 1 to 4 carbon atoms. X ⁻ represents COO ⁻ or SO ₃ ^— .

  Specific examples of the zwitterionic monomer having a polymerizable double bond include N-methacryloyloxyethyl-N, N-dimethylammonium-α-carboxybetaine (GLBT), N, N-dimethyl-N- (2- And methacryloyloxyethyl) -N- (3-sulfopropyl) ammonium betaine (SPE).

  The content ratio of the zwitterionic monomer having a polymerizable double bond in all monomers constituting the (meth) acrylic polymer is preferably 0.1% by weight or more, and 0.5% by weight or more. Is preferred. If it is less than 0.1% by weight, the anti-contamination effect tends to be insufficient. On the other hand, the upper limit of the content ratio is preferably 10% by weight, and preferably 5% by weight. When it is more than 10% by weight, the water resistance tends to decrease.

  As the (B) component, the most preferable polymer is the above (meth) acrylic acid ester monomer, carboxyl group-containing monomer, and both ions having a polymerizable double bond in which the above (C2) component is constituted by polymerization. And a copolymer of a monomer group having a polymerizable monomer.

  The mixing ratio of the (meth) acrylic acid ester-based monomer, the carboxyl group-containing monomer, and the zwitterionic monomer having a polymerizable double bond constituted by the polymerization (C2) component is a weight ratio of acrylic acid Ester monomer / carboxyl group-containing monomer / zwitterionic monomer having a polymerizable double bond, 99.4 / 0.5 / 0.1-80 / 10/10 is good, 98.5 / 1.0 / 0.5-90 / 5.0 / 5.0 is preferable. If it deviates from this range, it becomes difficult to satisfy the water resistance, frost damage resistance, and contamination resistance in a well-balanced manner.

  The glass transition temperature (Tg) of the component (B) is preferably −30 ° C. or higher, and preferably 0 ° C. or higher. When it is lower than −30 ° C., the surface of the coating film tends to be sticky and contaminants tend to adhere. On the other hand, the upper limit of Tg is preferably 70 ° C, and preferably 50 ° C. When the temperature is higher than 70 ° C., it is necessary to use a large amount of a film-forming auxiliary in order to maintain the film-forming property, and the contamination resistance is likely to deteriorate.

  The (meth) acrylic polymer can be obtained by, for example, a usual suspension polymerization method, dispersion polymerization method, or emulsion polymerization method. Among these, emulsion polymerization is preferable from the viewpoint of the environment. This emulsion polymerization reaction is carried out in the presence of an emulsifier by supplying the above monomers and polymerization initiator all at once or at a predetermined temperature with stirring in an aqueous medium.

In addition, said Tg means the value calculated by following formula (1).
1 / Tg = Wa / Tga + Wb / Tgb + (1)
In the formula (1), Tg is the glass transition temperature (K) of the copolymer, Tga and Tgb are the glass transition temperature (K) of the homopolymer of monomer a and monomer b, respectively, Wa And Wb indicate the weight fraction (%) of monomer a and monomer b, respectively.

  The emulsifier is usually used in a range of 0.05 to 10% by weight, preferably 0.1 to 5% by weight, based on the total amount of the polymerization monomers. As this emulsifier, an anionic, cationic or nonionic surfactant can be used. And these emulsifiers can select and use 1 type (s) or 2 or more types.

  Specific examples of the anionic surfactant include potassium oleate, sodium laurate, sodium dodecylbenzenesulfonate, sodium alkanesulfonate, sodium alkylnaphthalenesulfonate, sodium dialkylsulfosuccinate, sodium polyoxyethylene alkyl ether sulfate. , Non-reactive surfactants such as sodium polyoxyethylene alkyl allyl ether sulfate, polyoxyethylene alkyl phosphate ester, polyoxyethylene alkyl allyl phosphate ester, and alkyl allyl sulfosuccinate (for example, Sanyo Kasei Co., Ltd .: Eleminol ( Registered trademark) JS-2, for example, manufactured by Kao Corporation: latemuru (registered trademark) S-180A, S-180, etc.), polyoxyethylene alkylpropenyl phenyl -Sulfuric acid ester ammonium salt (for example, manufactured by Daiichi Kogyo Seiyaku Co., Ltd .: Aqualon (registered trademark) HS-10, HS-5, BC-10, BC-5 etc.), α-sulfo-ω- (1 -(Nonylphenoxy) methyl-2- (2-propenyloxy) ethoxy) -poly (oxy-1,2-ethanediyl) ammonium salt (for example, Adeka Soap (registered trademark) SE-10 manufactured by Asahi Denka Kogyo Co., Ltd.) , SE-1025A and the like), polyoxyethylene-1- (allyloxymethyl) alkyl ether sulfate ammonium salt (for example, Dairon Kogyo Seiyaku Co., Ltd .: Aqualon (registered trademark) KH-10) and the like. ), Α-sulfo-ω- (1- (alkoxy) methyl-2- (2-propenyloxy) ethoxy) -poly (oxy-1,2-ethanedi) Yl) ammonium salt (for example, Asahi Denka Kogyo Co., Ltd .: Adekaria Soap (registered trademark) SR-10, SR-1025, etc.), polyoxyalkylene alkenyl ether sulfate ammonium salt (for example, Kao Co., Ltd .: Latemu) (Registered trademark) PD-104 and the like) and the like.

  Specific examples of the cationic surfactant include non-reactive surfactants such as stearylamine hydrochloride, lauryltrimethylammonium chloride, and trimethyloctadecylammonium chloride.

  Specific examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene oxypropyl block polymer, polyethylene glycol fatty acid ester, polyoxyethylene sorbitan fatty acid ester and the like. Surfactant, α-hydro-ω- (1-alkoxymethyl-2- (2-propenyloxy) ethoxy) -poly (oxy-1,2-ethanediyl)) (Asahi Denka Kogyo Co., Ltd .: Adeka Rea soap ER-10, ER-20, ER-30, ER-40), polyoxyethylene alkylpropenyl phenyl ether (Daiichi Kogyo Seiyaku Co., Ltd .: Aqualon RN-20, RN-30, RN-50), polyoxy Alkylalkenyl ether (manufactured by Kao Corporation: Latemul P Reactive surfactants such as D-420, PD-430, and PD-450).

  Furthermore, as the above-mentioned emulsifier, an amphoteric surfactant can be used as the amphoteric component in addition to those described above. By using this amphoteric surfactant, in particular, the feature of improving the stain resistance can be exhibited. This amphoteric surfactant corresponds to the component (C1) among the components (C) described later.

  Specific examples of the amphoteric surfactant include lauryl betaine, lauryl dimethylaminoacetic acid betaine, stearyl dimethylaminoacetic acid betaine, lauryl dimethylamine oxide, 2-lauryl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine. , 2-stearyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, lauric acid amidopropyl betaine, stearic acid amidopropyl betaine, coconut amidopropyl betaine, lauryl hydroxysulfobetaine, stearyl hydroxysulfobetaine, etc. Surfactants.

  The content of the amphoteric surfactant with respect to the solid content of the aqueous dispersion according to the present invention is preferably 0.5% by weight or more, and more preferably 1.0% by weight or more. If it is less than 0.5% by weight, the stain resistance may be insufficient. On the other hand, the upper limit of the content ratio is preferably 10% by weight, and preferably 5% by weight. When it is more than 10% by weight, the water resistance tends to be insufficient.

  In addition to the above-mentioned emulsifier, water-soluble polymer polyvinyl alcohol, hydroxyethyl cellulose, water-soluble acrylic copolymer, copolymer of sodium styrenesulfonate, and the like can be used alone or in combination with the above-mentioned emulsifier.

  The monomer concentration during the polymerization is usually 30 to 70% by weight, preferably 35 to 65% by weight. As the polymerization initiator, generally used radical polymerization initiators such as ammonium persulfate and persulfuric acid are used. Persulfates such as potassium and sodium persulfate, azo polymerization initiators such as 2,2′-azobisisobutylnitrile and 2,2′-azobis (2,4-dimethylvaleronitrile), benzoyl peroxide, lauryl per Peroxide-based polymerization initiators such as oxide can be used.

  The amount of radical polymerization initiator used may be about 0.05 to 10% by weight, preferably about 0.05 to 8% by weight, based on the total amount of charged monomers.

  The reaction time is usually about 2 to 16 hours, and the temperature during polymerization is usually about 60 to 100 ° C.

((C) component)
The zwitterionic component constituting the component (C) is a component used for the purpose of improving stain resistance. This (C) component should just exist in the aqueous dispersion liquid concerning this invention, and the presence form is not ask | required. For example, the above-mentioned amphoteric surfactant (C1) component may be mixed in the aqueous dispersion, may be a constituent unit (C2) component constituting the component (B), or other These components may be a zwitterionic component, or may be a plurality of components including both the component (C1) and the component (C2). When the component (C) is the structural unit (C2) component constituting the component (B), the zwitterionic monomer having the polymerizable double bond, wherein the component (C2) is constituted by polymerization, Used as part of the monomer to be copolymerized.

((D) component)
In addition to the above components (A), (B) and (C), colloidal silica as component (D) is added to the aqueous dispersion according to the present invention for the purpose of improving stain resistance. be able to. This component (D) is a particle in which fine particles of silica are dispersed in an aqueous medium, and this silica colloidal aqueous dispersion includes those that are acidic in the state of the aqueous dispersion and those that are basic. There are, however, either. In addition, it is also possible to use cationic colloidal silica that is specially treated to have a positive charge on the surface of silica particles that are negatively charged and anionic.

Specific examples of the colloidal aqueous dispersion of silica showing acidity include, for example, Snowtex O (trade name, SiO ₂ solid content: 20%), Snowtex OL (trade name, SiO ₂ solid content: 20%), Snowtex OUP (trade name, SiO ₂ solid content: 15%) (the above is manufactured by Nissan Chemical Industries, Ltd.), Adelite AT-20Q (trade name, manufactured by Asahi Denka Kogyo Co., Ltd., SiO ₂ solid content: 20% ), Cataloid SN (trade name, manufactured by Catalyst Chemical Industry Co., Ltd., SiO ₂ solid content: 20%), silica dol-20A (trade name, manufactured by Nippon Chemical Industry Co., Ltd., SiO ₂ solid content: 20%), etc. Can be given.

Specific examples of the colloidal aqueous dispersion of silica exhibiting basicity include, for example, Snowtex 30 (trade name, SiO ₂ solid content: 30%), Snowtex C (trade name, SiO ₂ solid content: 20%). ), Snowtex N (trade name, SiO ₂ solid content: 20%), Snowtex S (trade name, SiO ₂ solid content: 30%), Snowtex UP (trade name, SiO ₂ solid content: 20%), Snowtex 20L (trade name, SiO ₂ solid content: 20%), Snowtex CM (trade name, SiO ₂ solid content: 30%), Snowtex XL (trade name, SiO ₂ solid content: 40%), Snowtex YL (trade name, SiO ₂ solid content: 40%), Snowtex ZL (trade name, SiO ₂ solid content: 40%), Snowtex MP-1040 (trade name, SiO ₂ solid content: 0%), Snowtex MP-2040 (trade name, SiO ₂ solid content: 40%), Snowtex MP-3040 (trade name, SiO ₂ solid content: 40%) (or more manufactured by Nissan Chemical Industries, Ltd.) Adelite AT-20 (trade name, SiO ₂ solid content: 20%), Adelite AT-20N (trade name, SiO ₂ solid content: 20%), Adelite AT-20A (trade name, SiO ₂ solid content: 20%) (The above is manufactured by Asahi Denka Kogyo Co., Ltd.), Cataloid S-20H (trade name, SiO ₂ solid content: 20%), Cataloid SI-30 (trade name, SiO ₂ solid content: 30%), Cataloid SI- 80P (trade name, SiO ₂ solid content: 40%), Cataloid SA (trade name, SiO ₂ solid content: 30%) (the above is manufactured by Catalyst Chemical Industry Co., Ltd.), Silica Dole-20 (trade name, SiO ₂ Solid content 0%), silica Doll -20B (trade name, SiO ₂ solid content: 20%) (more than Nippon Chemical Industrial Co., Ltd. are exemplified, Ltd.).

Moreover, as a colloidal aqueous dispersion of silica showing cationic property, Snowtex AK (trade name, manufactured by Nissan Chemical Industries, SiO ₂ solid content: 18%), Adelite CT-100 (trade name, Asahi Denka) Industrial Co., Ltd., SiO ₂ solid content: 20%), Silica Doll-20P (trade name, manufactured by Nippon Chemical Industry Co., Ltd., SiO ₂ solid content: 20%) and the like.

  Such colloidal silica particles as component (D) may be used singly or in combination of two or more. When combining two or more types, the same ionic ones or different ionic ones may be used in combination.

  The amount of component (D) used relative to the total amount of component (A), component (B) and component (C) is preferably 3% by weight or more, and more preferably 5% by weight or more. When it is less than 3% by weight, the stain resistance tends to be insufficient. On the other hand, the upper limit of the mixing amount is preferably 40% by weight, and preferably 30% by weight. When the amount is more than 40% by weight, the frost damage resistance, the glossiness and the coating film formability tend to deteriorate.

(Aqueous dispersion)
As described above, the aqueous dispersion according to the present invention comprises the components (A) to (C) and, if necessary, the component (D). The component (C) may be used as an emulsifier, a monomer, or an emulsifier and a monomer. On the other hand, (A) component and (D) component are not normally used directly in the case of manufacture of (B) component. The timing of adding the component (A) and the component (D) may be during the production of the component (B) or after the production.

  The aqueous dispersion thus obtained can be used as an aqueous paint by blending a pigment, various other additives, and the like within a range that does not impair the object and effect of the present invention. Examples of the pigment include coloring pigments and extender pigments. Examples of various additives include dispersants, thickeners, sagging inhibitors, ultraviolet absorbers, light stabilizers, antifoaming agents, and organic solvents.

  When the total solid content of each component contained in the aqueous dispersion is 100 parts by weight, the blending amount of the pigment is preferably 30 parts by weight or more, and preferably 50 parts by weight or more. When the amount is less than 30 parts by weight, the concealability is not good. On the other hand, the upper limit of the amount of the pigment is 140 parts by weight, preferably 120 parts by weight. When the amount is more than 140 parts by weight, the gloss is remarkably lowered.

  The water-based paint can be applied to an object usually used for building materials or the like to form a coating film. As such a coating method, methods such as brush coating, roller coating, spray coating, and dip coating can be used. Examples of the article to be coated include wood, concrete materials, cement materials, calcium silicate and other ceramic materials.

EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, this invention is not limited by a following example, unless the summary is exceeded. First, test methods and raw materials are shown below.
[Measurement of solid content]
The adhesive composition was measured according to the method described in JIS K 6833.

[Glass transition temperature (Tg)]
It calculated according to following formula (1).
1 / Tg = Wa / Tga + Wb / Tgb + (1)
In the formula (1), Tg is the glass transition temperature (K) of the copolymer, Tga and Tgb are the glass transition temperature (K) of the homopolymer of monomer a and monomer b, respectively, Wa And Wb indicate the weight fraction (%) of monomer a and monomer b, respectively.

[Left stability]
The obtained paint was put in a 100 ml plastic container and left in a dryer at 50 ° C. for 7 days, and the change in viscosity before and after standing and the state of gelation were visually observed and evaluated according to the following criteria.
○: No change △: Thickening is observed ×: Gelled

[Frost damage test]
The obtained paint is applied to a 150 mm x 70 mm x 5 mm slate plate coated with an aqueous sealer to a coating amount of 250 g / m ² and dried and cured for 7 days under conditions of 23 ° C and 50% RH. Did. Then, according to the following frost damage test cycle, the number of cycles until cracks occurred in the coating film was measured and evaluated according to the following criteria.
1 cycle of frost damage = (immersion in water at 23 ° C. for 12 hours) × (standing at −20 ° C. for 12 hours)
・ Evaluation ○: No change in appearance of coating film in test of 10 cycles or more Δ: Crack occurred on the coating film surface in 5 cycles or more and less than 10 cycles ×: Cracking in coating film surface in less than 5 cycles ( Cracks)

[Rain dripping resistance]
The obtained paint was applied to a 150 mm × 70 mm × 5 mm slate plate coated with an aqueous sealer so that the coating amount was 250 g / m ^2, and dried and cured for 7 days under conditions of 23 ° C. and 50% RH. Next, it was installed outdoors with the painted surface facing north and vertical, exposed for 1 month, counted the number of rain stripes before and after exposure, and evaluated according to the following criteria.
◎: Number of rain streaks 0: Number of rain streaks 1 to 2 △: Number of rain streaks 3 to 5 ×: Number of rain streaks 6 or more

(Raw materials used)

[(A) component]
-KC89S: Methyltrimethoxysilane oligomer, manufactured by Shin-Etsu Chemical Co., Ltd .: KC-89S (trade name)

[Monomer for producing component (B) (excluding monomer constituting component (C2))]
・ Cyclohexyl methacrylate: manufactured by Asahi Kasei Kogyo Co., Ltd., hereinafter abbreviated as “CHMA”.
-Methyl methacrylate: manufactured by Mitsubishi Rayon Co., Ltd., hereinafter abbreviated as "MMA".
・ 2-ethylhexyl acrylate: manufactured by Mitsubishi Chemical Corporation, hereinafter abbreviated as “2EHA”.
-Hydroxyethyl methacrylate: manufactured by Mitsubishi Rayon Co., Ltd., hereinafter abbreviated as “HEMA”.
Acrylic acid: manufactured by Mitsubishi Chemical Corporation, hereinafter abbreviated as “AA”.

[Emulsifier (excluding (C1) component)]
Polyoxyethylene alkylpropenyl ether sulfate ammonium salt: manufactured by Daiichi Kogyo Seiyaku Co., Ltd .: Aqualon BC-10 (trade name), hereinafter abbreviated as “BC10”.

[Component (C)]
<(C1) component>
Lauryldimethylaminoacetic acid betaine: manufactured by Kao Corporation: Amphithol 20BS (trade name), active ingredient 30% by weight, non-reactive carboxybetaine, hereinafter abbreviated as “amphital”.

<(C2) component>
N, N-dimethyl-N- (2-methacryloyloxyethyl) -N- (3-sulfopropyl) ammonium betaine: manufactured by RASCHIG: Reactive sulfobetaine, hereinafter abbreviated as “SPE”.
N-methacryloyloxyethyl-N, N-dimethylammonium-α-carboxybetaine: manufactured by Osaka Organic Chemical Co., Ltd .: Reactive carboxybetaine monomer, hereinafter abbreviated as “GLBT”.

(Aqueous dispersion containing component (D))
-The colloidal silica shown below was processed in the ultrasonic washing machine (Nippon Seiki Seisakusyo Co., Ltd. product: NS200-6U, 28 KHz) over 20 minutes, and the aqueous dispersion of colloidal silica was obtained.
Colloidal silica: manufactured by Nissan Chemical Industries, Ltd .: Snowtex XL treated by the following method, average particle size: 79.7 nm, ζ potential: −55.31 mV (hereinafter referred to as “XL”)

(Examples 1-8 , Comparative Examples 1-3 )
In a 1 L flask equipped with a stirrer, reflux condenser and raw material inlet, 50.0 parts by weight of ion-exchanged water and the emulsifier shown in Table 1 are charged in the amounts shown in Table 1, and the internal temperature is set to 75 ° C. While maintaining, as a polymerization initiator, 0.3 parts by weight of ammonium persulfate (APS) was added, and then 55.0 parts by weight of ion-exchanged water and an amount of emulsifier described in Table 1 were mixed in Table 1. The emulsion mixture obtained by mixing each component in the amount of was added dropwise over 3 hours as a drop solution.
After completion of the dropwise addition, the internal temperature was raised to 80 ° C. and aged for 4 hours. Then, 25 wt% aqueous ammonia was added as a pH adjuster so that the pH of the emulsion was 7-9, and the emulsion was cooled to 30 ° C to obtain an emulsion. And as needed, (D) component shown in Table 1 was added, and the aqueous dispersion liquid was obtained. Each of the above evaluations was performed using this aqueous dispersion. The results are shown in Table 1.

Claims (6)

A dispersion containing an organosiloxane or a hydrolyzate thereof (A) and a (meth) acrylic polymer (B) having a glass transition temperature of −30 to 70 ° C. In the dispersion, an amphoteric component the (C) possess,
The component (C) contains the structural unit (C2) constituting the component (B),
The component (B) has at least a (meth) acrylic acid ester monomer containing cyclohexyl (meth) acrylate, a carboxyl group-containing monomer, and a polymerizable double bond in which the component (C2) is constituted by polymerization. An aqueous dispersion which is a copolymer of a monomer group having an amphoteric monomer . Component (C), the aqueous dispersion of claim 1 comprising a zwitterionic surfactant (C1). The polymerizable zwitterionic group zwitterionic monomer having a double bond, an aqueous dispersion according to claim 1 is a betaine zwitterionic groups. A (meth) acrylate monomer containing at least cyclohexyl (meth) acrylate, a carboxyl group-containing monomer, and a zwitterionic monomer having a polymerizable double bond comprising the component (C2) by polymerization. The mixing ratio is 99.4 / 0.5 / 0.1-80 / 10 / in the weight ratio of (meth) acrylic acid ester monomer / carboxyl group-containing monomer / zwitterionic monomer having a polymerizable double bond. The aqueous dispersion according to claim 1 , wherein the aqueous dispersion is 10. In addition to the above components (A), (B) and (C), colloidal silica (D) is added to 3 to 3 with respect to the total amount of components (A), (B) and (C). The aqueous dispersion according to any one of claims 1 to 4 , containing 40% by weight. An aqueous paint using the aqueous dispersion according to any one of claims 1 to 5 .