JP5620138B2 - Water-based coating composition and method for producing the same - Google Patents

Description

  The present invention relates to an aqueous coating composition containing a (meth) acrylic polymer emulsion (A) and an aqueous silicone resin dispersion (B). In particular, the present invention relates to a water-based paint composition intended for architectural paints and / or household paints.

  In general, a paint having a low gloss is required as a paint for exterior walls of buildings. As a technique for producing a low gloss paint, inorganic fine particle matting agents such as silica, talc, clay and calcium carbonate, and organic fine particle matting agents such as crosslinked unsaturated polyester are used. Such a matting agent for paint has the disadvantage that the paint thickens and settles because it is fine particles. On the other hand, a matting agent for water-based paints containing an alkylene oxide addition polymer of monool or polyol has been proposed in order to control thickening and sedimentation of the paint (Patent Document 1). However, when such a matting agent is used, water resistance and weather resistance are lowered.

  As another technique, it is well known that an aqueous coating composition of an aqueous polymer emulsion and an aqueous silicone resin dispersion has a low gloss coating and water repellency. However, with such an aqueous coating composition, high storage stability cannot be obtained, and if the ratio of the silicone resin aqueous dispersion is small, a low gloss coating cannot be formed. On the other hand, when there are many silicone resin water dispersions, the problem that film-forming becomes inadequate will generate | occur | produce.

  In addition, an aqueous resin composition containing a fatty acid-modified resin aqueous dispersion and a silicone resin aqueous dispersion has been proposed (Patent Document 2). It can be cured at room temperature and has good film formability, but a low gloss coating cannot be obtained. Furthermore, the coating composition containing the metal oxide which has a photocatalytic action with a silicone resin aqueous dispersion is disclosed (patent document 3). By using this coating composition, an uneven coating film is formed, and a low gloss coating film is obtained. However, this coating composition also has the disadvantage of poor storage stability.

JP 2008-255194 A JP 2008-255194 A JP 2004-315727 A

  The object of the present invention is to maintain a water repellency characteristic of a silicone resin aqueous dispersion, while being able to form a coating film with low gloss and good water resistance, weather resistance, and stain resistance, and storage stability. It is to provide a water-based paint composition having good properties.

  As a result of intensive studies to solve the above problems, the present inventors polymerize a (meth) acrylic monomer containing a predetermined amount of a hydroxyl group-containing polymerizable monomer ( A mixture containing a specific amount of the silicone resin aqueous dispersion (B) and the high HLB surfactant (C) in the (meth) acrylic polymer emulsion (A) is surprisingly a stable aqueous coating composition. The present inventors have found that a coating film having excellent water repellency, weather resistance, stain resistance and water resistance and a low gloss can be formed, and the present invention has been completed based on the above findings.

The present invention has the following aspects.
[1] A (meth) acrylic polymer emulsion (A) obtained by polymerizing a (meth) acrylic monomer containing 2 to 15% by mass of a hydroxyl group-containing polymerizable monomer, an aqueous silicone resin dispersion ( B), and a water-based coating composition containing a high HLB surfactant (C) having an HLB of 16 to 20, wherein the high HLB surfactant (C) is converted into a (meth) acrylic polymer emulsion (A). An aqueous coating composition containing 0.2 to 2 parts by mass with respect to 100 parts by mass.
[2] The water-based coating composition according to [1], wherein the particle diameter of the (meth) acrylic polymer emulsion (A) is 110 to 250 nm.
[3] The mass ratio of the (meth) acrylic polymer emulsion (A) and the silicone resin aqueous dispersion (B) is in the range of 80-20 / 20-80, according to [1] or [2] Water-based paint composition.
[4] In any one of [1] to [3], the (meth) acrylic polymer emulsion (A) is formed by emulsion polymerization in the presence of an ultraviolet absorber and / or a light stabilizer. The water-based coating composition as described.
[5] A method for producing a water-based coating composition according to any one of [1] to [4], wherein 1) a step of forming a (meth) acrylic polymer emulsion (A), and 2) A method for producing an aqueous coating composition comprising a step of mixing a (meth) acrylic polymer emulsion (A), an aqueous silicone resin dispersion (B), and a high HLB surfactant (C) in this order.
[6] A method for producing an aqueous coating composition according to any one of [1] to [4], wherein 1) a step of forming a (meth) acrylic polymer emulsion (A), 2) ( A step of making a mixed solution of a (meth) acrylic polymer emulsion (A) and a high HLB surfactant (C), and 3) a (meth) acrylic polymer emulsion (A) and a high HLB surfactant (C) A method for producing a water-based coating composition, comprising the step of mixing the silicone resin aqueous dispersion (B) in this order with a mixed solution of

  The water-based coating composition according to the present invention has good storage stability and low gloss, water repellency, water resistance, weather resistance, gloss retention (appearance even when only a small amount of the silicone resin aqueous dispersion (B) is used. With regard to durability, the coating film excellent in stain resistance can be formed. Therefore, the water-based coating composition is useful as a coating material, an outer wall material of a building material or a finishing material, particularly as a coating material or a finishing material of a building material.

  Hereinafter, various components contained in the water-based coating composition of the present invention will be described in more detail.

(Meth) acrylic polymer emulsion (A)
In the aqueous coating composition of the present invention, the (meth) acrylic polymer emulsion (A) used in combination with the silicone resin aqueous dispersion (B) contains 2 to 15% by mass of a hydroxyl group-containing polymerizable monomer. It is a (meth) acrylic polymer emulsion obtained by polymerizing a (meth) acrylic monomer. The (meth) acrylic polymer emulsion is characterized in that it is stable and forms a transparent coating film with sharpness alone. However, a low gloss and translucent coating film can be obtained from an aqueous coating composition obtained by mixing the (meth) acrylic polymer emulsion and the silicone resin aqueous dispersion (B). Further, in general, in the case of a single clear coating film, as the amount of the hydroxyl group-containing polymerizable monomer in the water-based coating composition increases, the gloss of the coating film increases. By mixing the (meth) acrylic polymer emulsion formed using the group-containing polymerizable monomer with the silicone resin aqueous dispersion (B), the very interesting phenomenon that the gloss of the resulting coating film decreases I found it. Hereinafter, the detail of the raw material used at the time of manufacturing a (meth) acrylic-type polymer emulsion (A) is demonstrated.

[Hydroxyl group-containing polymerizable monomer]
Specific examples of the hydroxyl group-containing polymerizable monomer used in the present invention include 2-hydroxyethyl (meth) acrylate, 4-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, caprolactone-modified ( Examples include hydroxyl group-containing (meth) acrylates such as (meth) acrylate, polyethylene glycol (meth) acrylate, and polypropylene glycol (meth) acrylate, and one or more selected from these groups can be used. Particularly preferred is 2-hydroxyethyl (meth) acrylate. It is important to use 2 to 15% by mass of one or more of these hydroxyl group-containing polymerizable monomers with respect to the entire polymerizable monomer used to obtain the (meth) acrylic polymer emulsion. is there. A (meth) acrylic emulsion obtained from such a monomer is mixed with the silicone resin aqueous dispersion (B) to form a low gloss and translucent coating film with excellent water resistance. It becomes possible to do. In particular, from the viewpoint of water resistance, it is most preferable to use 3 to 10% by mass of a hydroxyl group-containing polymerizable monomer.

[Alkoxysilane group-containing polymerizable monomer]
Examples of alkoxysilane group-containing polymerizable monomers used for the preparation of (meth) acrylic polymer emulsions include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, vinylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-acryloxypropylmethyldimethoxysilane, γ-methacryloxypropyl Examples thereof include triethoxysilane and γ-methacryloxypropylmethyldiethoxysilane, and one or more selected from these groups can be used. Particularly preferred are γ-methacryloxypropyltrimethoxysilane and γ-methacryloxypropyltriethoxysilane. Furthermore, it is preferable to use 0.1-10 mass% alkoxysilane group containing polymerizable monomer with respect to the whole polymerizable monomer used in order to obtain a (meth) acrylic-type polymer emulsion. In particular, from the viewpoint of polymerization stability, blending stability, and water resistance of the resulting coating film, 0.1 to 5% by mass is preferable.

[Carboxyl group-containing polymerizable monomer]
Specific examples of the carboxyl group-containing polymerizable monomer used in the preparation of the (meth) acrylic polymer emulsion include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, maleic anhydride and the like. 1 or 2 or more selected from these groups can be used. Acrylic acid and methacrylic acid are particularly preferred. Furthermore, it is preferable to use 0.5-10 mass% carboxyl group-containing polymerizable monomer with respect to the whole polymerizable monomer used in order to obtain a (meth) acrylic-type polymer emulsion. In particular, 1 to 5% by mass is preferable from the viewpoint of the storage stability after blending with the silicone resin aqueous dispersion.

  There are no particular limitations on the polymerizable monomers other than those used in the preparation of the (meth) acrylic polymer emulsion, and examples thereof include aromatic monomers such as (meth) acrylic acid esters, styrene, vinyltoluene, and acetic acid. Examples include vinyl esters such as vinyl, vinyl propionate and vinyl persuccinate, vinyl cyanides such as (meth) acrylonitrile, vinyl halides such as vinyl chloride and vinylidene chloride, and butadiene. Further, various functional monomers such as (meth) acrylamide, diacetone acrylamide, vinyl pyrrolidone, glycidyl (meth) acrylate, N-methylol acrylamide, N-butoxymethyl acrylamide, divinylbenzene, methyl vinyl ketone and the like can be mentioned. It is done.

  Specific examples of (meth) acrylic acid esters include (meth) acrylic acid alkyl esters having 1 to 18 carbon atoms in the alkyl group and (poly) oxyethylene mono (meth) having 1 to 100 ethylene oxide groups. Examples thereof include acrylate, (poly) oxypropylene mono (meth) acrylate, and (poly) oxyethylene di (meth) acrylate having 1 to 100 ethylene oxide groups. Specific examples of the (meth) acrylic acid alkyl ester include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and (meth) acrylic acid t-. Examples include butyl, 2-ethylhexyl (meth) acrylate, dodecyl (meth) acrylate, and (meth) acrylic acid cycloalkyl ester.

  When the acrylic polymer emulsion (A) has an acidic group, it is desirable to neutralize with a neutralizing agent in order to improve the mechanical stability of the particles of the acrylic polymer emulsion (A). . The neutralizing agent is not particularly limited as long as it can neutralize acidic groups. For example, sodium hydroxide, potassium hydroxide, trimethylamine, dimethylaminoethanol, 2-methyl-2-amino-1-propanol, Examples include triethylamine and aqueous ammonia. These neutralizing agents are desirably used in such an amount that the pH of the neutralized fatty acid-modified acrylic resin aqueous dispersion becomes about 7 to 10.

  In the acrylic polymer emulsion (A), the average particle size of the dispersion resin is preferably 110 to 250 nm, and particularly preferably 140 to 200 nm. When the dispersion resin has such an average particle diameter, the storage stability (storage stability) when blended with the silicone resin aqueous dispersion (B) is improved, and a low gloss coating film can be obtained. .

  As a method for producing the acrylic polymer emulsion (A), an ordinary multistage emulsion polymerization method can be employed. As a typical example, in the presence of an emulsifier and a polymerization initiator in water, a polymerizable monomer is usually emulsion-polymerized at a temperature of 60 to 90 ° C. with a pH of 4 or less. Is a method in which the above is repeated several times.

  The emulsifier is not particularly limited, and for example, an anionic emulsifier, a nonionic emulsifier, a cationic emulsifier, an amphoteric emulsifier, a polymer emulsifier, and the like can be used. For example, fatty acid salts such as sodium lauryl sulfate, higher alcohol sulfates, alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate, polyoxyethylene alkyl ether sulfates, polyoxyethylene polycyclic phenyl ether sulfates, polyoxynonyls Anionic surfactants such as phenyl ether sulfonate, polyoxyethylene-polyoxypropylene glycol ether sulfate, so-called reactive emulsifier having a sulfonic acid group or sulfate ester group and a polymerizable unsaturated double bond in the molecule Polyoxyethylene alkyl ether, polyoxyethylene nonylphenyl ether, sorbitan fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene-polyoxypropylene block copolymer, Nonionic surfactants such as reactive nonionic surfactants having a skeleton and a polymerizable unsaturated double bond in the molecule; Cationic surfactants such as alkylamine salts and quaternary ammonium salts; (Modified) Polyvinyl alcohol etc. are mentioned. These emulsifiers may be used alone or in combination of several kinds.

  The polymerization method for emulsion polymerization of a (meth) acrylic polymer emulsion includes a monomer batch charging method in which monomers are charged in batch, a monomer dropping method in which monomers are continuously dropped, and a simple method. Examples include a pre-emulsion method in which a monomer, water and an emulsifier are mixed and emulsified in advance, and these are added dropwise, or a combination thereof. The method for using the polymerization initiator is not particularly limited.

  As the polymerization initiator used for emulsion polymerization of the (meth) acrylic polymer emulsion, a general radical initiator can be used. A radical polymerization initiator is one that generates radicals by heat or a reducing substance to cause addition polymerization of a polymerizable monomer. Water-soluble or oil-soluble persulfates, peroxides, azobis compounds are included. Specifically, potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide, t-butyl hydroperoxide, t-butyl peroxybenzoate, 2,2-azobisisobutyronitrile, 2,2-azobis (2-diaminopropane) hydrochloride, 2,2-azobis (2,4-dimethylvaleronitrile) and the like are mentioned, and water-soluble ones are preferable. When acceleration of the polymerization rate or a low temperature reaction is desired, a reducing agent such as sodium bisulfite, ferrous chloride, ascorbic acid, formaldehyde sulfooxylate salt or the like can be used in combination with the radical polymerization initiator.

  For example, a (meth) acrylic polymer emulsion optionally contains a thickener, film-forming aid, plasticizer, antifreeze agent, antifoaming agent, dye, preservative, ultraviolet absorber, light stabilizer, etc. can do.

  Ultraviolet absorbers include benzophenone series, benzotriazole series, and triazine series. Specific examples of the benzophenone ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, and 2-hydroxy-4-n-octate. Xibenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, bis (5-benzoyl-4-hydroxy-2-methoxyphenyl) methane, 2,2'-dihydroxy-4 -Methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 2-hydroxy-4-methoxy -2'-Carboki Benzophenone, 2-hydroxy-4-stearyloxy benzophenone.

  Specific examples of the radical polymerizable benzophenone ultraviolet absorber include 2-hydroxy-4-acryloxybenzophenone, 2-hydroxy-4-methacryloxybenzophenone, 2-hydroxy-5-acryloxybenzophenone, 2-hydroxy-5. -Methacryloxybenzophenone, 2-hydroxy-4- (acryloxy-ethoxy) benzophenone, 2-hydroxy-4- (methacryloxy-ethoxy) benzophenone, 2-hydroxy-4- (methacryloxy-diethoxy) benzophenone, 2-hydroxy-4- And (acryloxy-triethoxy) benzophenone.

  Specific examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-5′-tert-butylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) benzotriazole, 2- (2-hydroxy-5-tert-octylphenyl) benzotriazole, 2- (2-hydroxy-3,5- Di-tert-octylphenyl) benzotriazole, 2- [2′-hydroxy-3 ′, 5′-bis (α, α′-dimethylbenzyl) phenyl] benzotriazole), methyl-3- [3-tert-butyl -5- (2H-benzotriazol-2-yl) -4-hydroxyphenyl] propionate and polyethylene Condensate with glycol (molecular weight 300) (manufactured by Ciba Geigy Japan, product name: TINUVIN 1130), isooctyl-3- [3- (2H (12) benzotriazol-2-yl) -5-tert-butyl-4 -Hydroxyphenyl] propionate (manufactured by Ciba Geigy Japan, product name: TINUVIN 384), 2- (3-dodecyl-5-methyl-2-hydroxyphenyl) benzotriazole (manufactured by Ciba Geigy Japan, product name: TINUVIN 571) 2- (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-amylphenyl) Benzotriazole, 2- (2′-hydroxy-4′-octoxyphenyl) benzoto Azole, 2- [2′-hydroxy-3 ′-(3 ″, 4 ″, 5 ″, 6 ″ -tetrahydrophthalimidomethyl) -5′-methylphenyl] benzotriazole, 2,2-methylenebis [ 4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], 2- (2H-benzotriazol-2-yl) -4,6-bis ( 1-methyl-1phenylethyl) phenol (manufactured by Nippon Ciba-Geigy Co., Ltd., product name: TINUVIN900).

  Specific examples of radically polymerizable benzotriazole-based ultraviolet absorbers include 2- (2′-hydroxy-5′-methacryloxyethylphenyl) -2H-benzotriazole (manufactured by Otsuka Chemical Co., Ltd., product name: RUVA- 93), 2- (2′-hydroxy-5′-methacryloxyethyl-3-tert-butylphenyl) -2H-benzotriazole, 2- (2′-hydroxy-5′-methacrylyloxypropyl-3-tert) -Butylphenyl) 5-chloro-2H-benzotriazole, 3-methacryloyl-2-hydroxypropyl-3- [3 '-(2 "-benzotriazolyl) -4-hydroxy-5-tert-butyl] phenylpropi Honate (Nippon Ciba-Geigy Co., Ltd., product name: CGL-104).

  Specific examples of the triazine-based ultraviolet absorber include TINUVIN 400 (product name, manufactured by Ciba Geigy Japan, Inc.).

  As the light stabilizer, hindered amine light stabilizers are preferable, among them, those having low basicity are more preferable, and those having a base constant (pKb) of 8 or more are particularly preferable. Specific examples of the light stabilizer include bis (2,2,6,6-tetramethyl-4-piperidyl) succinate, bis (2,2,6,6-tetramethylpiperidyl) sebacate, bis (1,2, 2,6,6-pentamethyl-4-piperidyl) 2- (3,5-di-tert-butyl-4-hydroxybenzyl) 2-butyl malonate, 1- [2- [3- (3,5-di -Tert-butyl-4-hydroxyphenyl) propynyloxy] ethyl] -4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propynyloxy] -2,2,6,6-tetra A mixture of methylpiperidine, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl-1,2,2,6,6-pentamethyl-4-piperidyl-sebacate (Nippon Chi Product made by Geigy Co., Ltd., product name: TINUVIN292), bis (1-octoxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, TINUVIN123 (product name, manufactured by Ciba-Geigy Japan), etc. It is done.

  Specific examples of the radical polymerizable hindered amine light stabilizer include 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate, 1,2,2,6,6-pentamethyl-4-piperidyl acrylate, 2 2,2,6,6-tetramethyl-4-piperidyl methacrylate, 2,2,6,6-tetramethyl-4-piperidyl acrylate, 1,2,2,6,6-pentamethyl-4-iminopiperidyl methacrylate, 2, , 2,6,6-tetramethyl-4-iminopiperidyl methacrylate, 4-cyano-2,2,6,6-tetramethyl-4-piperidyl methacrylate, 4-cyano-1,2,2,6,6- Examples include pentamethyl 4-piperidyl methacrylate.

  As a method for introducing the ultraviolet absorber and / or the light stabilizer into the (meth) acrylic emulsion, a method of introducing the ultraviolet absorber and / or the light stabilizer into the emulsion by being present during emulsion polymerization; A method of introducing into a (meth) acrylic polymer emulsion by mixing with an auxiliary agent, etc .; introducing into the emulsion; mixing an ultraviolet absorber and / or a light stabilizer with a film-forming auxiliary, a surfactant, water And then emulsifying and then adding to the (meth) acrylic polymer emulsion to introduce it into the emulsion. Moreover, when an ultraviolet absorber and a light stabilizer are used in combination, the resulting coating film exhibits excellent durability and gloss is further reduced due to their synergistic effect.

Silicone resin water dispersion (B)
In the aqueous coating composition of the present invention, the silicone resin aqueous dispersion (B) used in combination with the (meth) acrylic polymer emulsion (A) is emulsified and dispersed in an aqueous medium in the presence of an emulsifier. An emulsified composition is included.

  The organopolysiloxane constituting the silicone resin aqueous dispersion (B) is a resin having a structure in which silicon (Si) and oxygen (O) to which organic groups are bonded are alternately connected by chemical bonds. A resin called sesquioxane or silicone oil is wrapped.

  The organopolysiloxane is not particularly limited as long as it forms a coating film. For example, dimethylpolysiloxane, diethylpolysiloxane, dipropylpolysiloxane, dibutylpolysiloxane, diisopropylpolysiloxane, dihexylpolysiloxane, dioctylpolysiloxane. Examples include siloxane, ethyl methyl polysiloxane, methyl propyl polysiloxane, butyl methyl polysiloxane, isopropyl methyl polysiloxane, hexyl methyl polysiloxane, methyl octyl polysiloxane, ethyl propyl polysiloxane, butyl octyl polysiloxane, and the like. These organopolysiloxanes may be used alone or in combination of two or more.

  In the aqueous coating composition of the present invention, the mass ratio of the acrylic polymer emulsion (A) and the silicone resin aqueous dispersion (B) is preferably in the range of 80 to 20/20 to 80. By using both components in such a mass ratio, it is possible to form a coating film having excellent low glossiness and water resistance while maintaining high water repellency.

High HLB surfactant (C)
In the water-based coating composition of the present invention, a high HLB surfactant having an HLB of 16 to 20 is used in order to improve storage stability. In particular, the high HLB surfactant preferably has an HLB greater than 16, and more preferably has an HLB greater than 18. HLB here is a value calculated by the Griffin equation (HLB = 20 × (mass ratio of hydrophilic groups in the molecule)). A suitable surfactant is polyoxyethylene alkyl (C12-15) ether. A NEWCOL® surfactant obtained from Nippon Emulsifier Co., Ltd. has been found to be particularly useful in the present invention. In particular, NEWCOL (registered trademark) 2320 having an HLB of 16.4 and NEWCOL (registered trademark) 2399S having an HLB of 19.2 are most preferable. Emulgen 150 having an HLB of 18.3 obtained from Kao Corporation is also suitable.

  In the aqueous coating composition of the present invention, in order to stably disperse the acrylic polymer emulsion (A) and the silicone resin aqueous dispersion (B), a high HLB interface with respect to 100 parts by mass of the acrylic polymer emulsion (A). It is calculated | required that the quantity of an activator is 0.2-2 mass parts. Further, the amount of the high HLB surfactant is most preferably 0.5 to 1 part by mass.

  As a method for producing the water-based coating composition of the present invention, a (meth) acrylic polymer emulsion (A) is formed, and then the (meth) acrylic polymer emulsion (A) and a silicone resin aqueous dispersion (B ) And a high HLB surfactant (C). Alternatively, a (meth) acrylic polymer emulsion (A) is formed, and a mixed solution of the (meth) acrylic polymer emulsion (A) and the high HLB surfactant (C) is prepared, A method of mixing the silicone resin aqueous dispersion (B) with this mixed solution is exemplified. Compared to the aqueous coating composition obtained by the former method of simultaneously mixing the (meth) acrylic polymer emulsion (A), the silicone resin aqueous dispersion (B) and the high HLB surfactant (C), ( The aqueous coating composition obtained by the latter method of mixing the silicone resin aqueous dispersion (B) in the mixed liquid of the (meth) acrylic polymer emulsion (A) and the high HLB surfactant (C) is more storage. It is preferable in terms of more excellent stability.

  According to the present invention, a water-based coating composition is obtained that has good storage stability and can form a low-gloss coating having excellent water repellency, water resistance, weather resistance, and stain resistance without using pigments. It is done. In the water-based coating composition of the present invention, a (meth) acrylic polymer emulsion obtained from a monomer mixture containing a hydroxyl group-containing polymerizable monomer is used to blend with a small amount of an aqueous silicone resin dispersion. Only a low gloss coating is formed. Furthermore, even if only a small amount of the silicone resin aqueous dispersion is used, the water repellency, which is a feature of the coating film formed from the silicone resin aqueous dispersion, is also exceptionally excellent. Therefore, by using the water-based coating composition of the present invention, it is possible to form a coating film having excellent weather resistance and stain resistance. Further, in this water-based coating composition, by adding a high HLB surfactant to the blend composition of the (meth) acrylic polymer emulsion (A) and the silicone resin aqueous dispersion (B), an acrylic system is obtained. The compatibility between the polymer emulsion and the silicone resin aqueous dispersion is improved, and the problems of thickening and sedimentation are solved. By using a high HLB surfactant, the storage stability of the water-based coating composition over time is improved.

  Hereinafter, the present invention will be described in more detail with reference to specific production examples and examples. The present invention is not limited in any way by these examples. The “parts” and “%” described below are based on mass unless otherwise specified.

  First, the (meth) acrylic polymer emulsion, the water-based coating composition, and a method for evaluating the physical properties of the obtained coating film will be described.

Evaluation of polymerization stability The (meth) acrylic polymer emulsion obtained after emulsion polymerization was filtered through a 100-mesh filter cloth, and the residue mass was divided by the mass of the (meth) acrylic polymer emulsion to obtain a residue. Rate.
○: Residual rate is less than 100 ppm. Δ: Residual rate is 100 ppm or more and less than 1000 ppm. X: A large amount of aggregate is generated.

Measurement of Particle Diameter The average particle diameter of the obtained (meth) acrylic polymer emulsion was measured with a Microtrac particle size distribution meter manufactured by Leeds & Northrup.

Solid content ratio of (meth) acrylic polymer emulsion This is the dry mass after drying the (meth) acrylic polymer emulsion at 105 ° C. for 3 hours. More specifically, about 1 g of (meth) acrylic polymer emulsion was accurately weighed in an aluminum dish whose mass was previously known, dried at 105 ° C. for 3 hours with a constant temperature dryer, and then silica gel was added. In a desiccator, allow to cool for 30 minutes and then weigh accurately. The solid content was obtained by dividing the mass after drying of the substance by the mass before drying.

The storage-stable water-based coating composition was put in a 250 mm polycup by the 8th minute, and the initial viscosity and the viscosity after storage at 50 ° C. for 4 weeks were measured and evaluated as a viscosity change rate (rounded off to the nearest decimal place). The viscosity here was measured at 60 rpm using a TVB-10M viscometer manufactured by Toki Sangyo Co., Ltd.
A: Viscosity change rate is 20% or less compared to the initial viscosity.
○: The viscosity change rate is 30% or less compared to the initial viscosity.
Δ: The viscosity change rate is 40% or less compared to the initial viscosity.
X: Viscosity change rate is 41% or more compared with initial viscosity.

The coating film glossy water-based coating composition was applied to a wire coater No. 50 was applied to an ABS plate, forcedly dried at 100 ° C. for 5 minutes, and then dried at 50 ° C. for 1 week. About the coating film after drying, 60 degree gloss gloss was measured with the gloss meter (micro tri gloss micro, BYK Gardner make).
60 or more; glossy.
50-59; some gloss.
50 or less; no gloss.

Water contact angle This water contact angle is a scale for measuring the water repellency of a coating film, and the larger the value, the higher the water repellency.
The water-based coating composition was applied to a wire coater No. 50 was applied to a glass plate and left in an oven at 80 ° C. for 5 minutes. Further, after being allowed to stand at room temperature for 1 day, the water contact angle was measured in an atmosphere at a temperature of 23 ° C. and a humidity of 50%. If the water contact angle is 100 ° ± 3, it is determined that the water repellency is high. The water contact angle was measured with a CA-X150 type contact angle measuring device manufactured by Kyowa Interface Science Co., Ltd.

The water-resistant water- based coating composition was applied to a wire coater No. 50 was applied to an alumite sulfate plate and left in an oven at 80 ° C. for 5 minutes. Furthermore, after letting it stand at room temperature for 1 day, it was immersed in 40 degreeC water for 30 days, and the state was determined visually. Judgment criteria are as follows. ○ The above was accepted.
A: No blistering or glossiness is seen.
○: Slightly blistering but no glossiness.
Δ: There is blistering and glossiness is also seen.
X: The whole surface is blistering and glossy.

[Method for Producing Acrylic Polymer Emulsion (A)]
Production Example 1
In a reaction vessel equipped with a stirrer, reflux condenser, dropping tank and thermometer, 505 parts of water, Aqualon KH1025 (ammonium-α-sulfonato-ω-1- (allyloxymethyl) alkyloxypolyoxyethylene: Daiichi Kogyo Seiyaku ( 4.4 parts) was added, the temperature in the reaction vessel was raised to 80 ° C., 15 parts of 2% aqueous solution of ammonium peroxodisulfate was added, and 5 minutes later, 122 parts of methyl methacrylate (MMA) , Cyclohexyl methacrylate (CHMA) 50 parts, butyl methacrylate (BMA) 20 parts, butyl acrylate (BA) 236 parts, 2-ethylhexyl acrylate (2EHA) 40.75 parts, methacrylic acid (MAA) 6.25 parts, 2- Hydroxyethyl methacrylate (2HEMA) 25 parts, Aqualon KH1025 40 parts, 3 parts of styrene sulfonate, 25 parts of 2% aqueous solution of ammonium peroxodisulfate, 6 parts of γ-methacryloxypropyltrimethoxysilane (SZ6030 manufactured by Dow Corning Toray) and 245 parts of water The reaction vessel was charged into the reaction vessel over 120 minutes. The pH of the reaction system was maintained at 4 or lower. After the addition of the emulsified liquid mixture was completed, the temperature of the reaction vessel was kept at 80 ° C. as it was.

  Next, 115.5 parts of methyl methacrylate (MMA), 20 parts of cyclohexyl methacrylate (CHMA), 11 parts of butyl methacrylate (BMA), 33 parts of butyl acrylate (BA), 8 parts of methacrylic acid (MMA), acrylic acid (AA) ) 2 parts, 2-hydroxyethyl methacrylate (2HEMA) 10 parts, diacetone acrylamide (DAAm) 0.5 part, NEWCOL707SF (manufactured by Nippon Emulsifier Co., Ltd.) 7 parts, 2% aqueous solution of ammonium peroxodisulfate 10 parts, water 130 parts The emulsified mixed liquid consisting of was added from the dropping tank over 50 minutes. The pH of the reaction system was maintained at 4 or lower. The reaction vessel temperature was kept at 80 ° C. After the end of charging, the temperature was kept at 80 ° C. for 30 minutes.

  Next, 76 parts of methyl methacrylate (MMA), 30 parts of cyclohexyl methacrylate (CHMA), 12.25 parts of butyl methacrylate (BMA), 130 parts of butyl acrylate (BA), 33 parts of 2-ethylhexyl acrylate (2EHA), methacrylic acid (MAA) 3.75 parts, 2-hydroxyethyl methacrylate (2HEMA) 15 parts, NEWCOL707SF 7 parts, ammonium peroxodisulfate 2% aqueous solution 15 parts, γ-methacryloxypropyltrimethoxysilane (SZ6030 manufactured by Dow Corning Toray) ) An emulsified mixed solution consisting of 1 part and 143 parts of water was charged into the reaction vessel from the dropping tank over 70 minutes. The pH of the reaction system was maintained at 4 or lower. After the addition of the emulsified liquid mixture was completed, the temperature of the reaction vessel was 82 ° C., and stirring was continued for 60 minutes. Then, it cooled to room temperature. After cooling, the mixture was filtered with a 200 mesh wire net to remove aggregates and the like. After filtration, the pH was adjusted to 8 with 25% aqueous ammonia, and then water was added to adjust the solid content to 46% (Table 1).

Production Examples 2-8
An acrylic polymer emulsion was produced in the same manner as in Production Example 1 except that the amount and type of the hydroxyl group-containing polymerizable monomer were changed as shown in Table 1. For Production Example 2, the hydroxyl group-containing polymerizable monomer is unused. In Table 1, HEA is an abbreviation for 2-hydroxyethyl acrylate.

Production Example 9
To the acrylic polymer emulsion according to Production Example 1, 5 parts of a 25% surfactant, NEWCOL 2399S (manufactured by Nippon Emulsifier Co., Ltd.) was added and stirred for 30 minutes (Table 1).

Production Example 10
For the purpose of improving weather resistance, 10 parts of UV absorber (manufactured by Ciba Geigy Japan, product name: TINUVIN 400) and 10 parts of light stabilizer (manufactured by Ciba Geigy Japan, product name: TINUVIN 123) are manufactured. These additives were introduced into the (meth) acrylic polymer emulsion by being present during the emulsion polymerization to produce the (meth) acrylic polymer emulsion of Example 1.

Production Examples 11-17
An acrylic polymer emulsion was produced in the same manner as in Production Example 1 except that the amount of the initial surfactant was changed as shown in Table 2 for the purpose of controlling the particle size of the acrylic polymer emulsion. About the acrylic polymer emulsion of each of these production examples, the results of physical property evaluation are shown in Tables 1-2.

Example 1
100 parts of the acrylic polymer emulsion of Production Example 1, 100 parts of a silicone resin emulsion (WACKER BS45 manufactured by Asahi Kasei Silicone Co., Ltd.), and a surfactant having a HLB of 19.2 (NEWCOL2399S manufactured by Nippon Emulsifier Co., Ltd.) "Ne-2399S")) 0.5 part was mixed and stirred for 60 minutes using a stirrer to prepare a water-based coating composition.

Examples 2-6, 8
100 parts of acrylic polymer emulsions of Production Examples 3 to 7, 10 parts, 100 parts of a silicone resin emulsion (WACKER BS45 manufactured by Asahi Kasei Silicone Co., Ltd.), and a surfactant having an HLB of 19.2 (Nippon Emulsifier Co., Ltd.) 0.5 parts of NEWCOL2399S manufactured) was mixed and stirred for 60 minutes using a stirrer to prepare a water-based coating composition.

Example 7
100 parts of the acrylic polymer emulsion of Production Example 9 and 100 parts of a silicone resin emulsion (WACKER BS45 manufactured by Asahi Kasei Silicone Co., Ltd.) are blended and mixed with stirring for 60 minutes to prepare a water-based coating composition. did.

Examples 9-14
100 parts of the acrylic polymer emulsion of Production Example 1, 100 parts of a silicone resin emulsion (WACKER BS45 manufactured by Asahi Kasei Silicone Co., Ltd.), and a high HLB surfactant (NEWCOL2320 manufactured by Nippon Emulsifier Co., Ltd. of HLB16.4 (Table) "Ne-2320"), Emulgen 150 manufactured by Kao Corporation of HLB18.3 ("Em150" in the table), or NEWCOL2399S manufactured by Nippon Emulsifier Co., Ltd. of HLB19.2 ("Ne-2399S" in the table)) Was mixed with stirring using a stirrer for 60 minutes to prepare a water-based coating composition.

Examples 15-19
100 parts of an acrylic polymer emulsion of Production Examples 11 to 15, 100 parts of a silicone resin emulsion (WACKER BS45 manufactured by Asahi Kasei Silicone Co., Ltd.), and a surfactant having a HLB of 19.2 (NEWCOL2399S manufactured by Nippon Emulsifier Co., Ltd.) ) 0.5 parts was mixed and stirred for 60 minutes using a stirrer to prepare a water-based coating composition.

Example 20
160 parts of the acrylic polymer emulsion of Production Example 1, 40 parts of a silicone resin emulsion (WACKER BS45 manufactured by Asahi Kasei Silicone Co., Ltd.), and a surfactant having a HLB of 19.2 (NEWCOL2399S manufactured by Nippon Emulsifier Co., Ltd.) 0 8 parts was mixed and stirred for 60 minutes using a stirrer to prepare a water-based coating composition.

Example 21
120 parts of the acrylic polymer emulsion of Production Example 1, 80 parts of a silicone resin emulsion (WACKER BS45 manufactured by Asahi Kasei Silicone Co., Ltd.), and a surfactant having a HLB of 19.2 (NEWCOL2399S manufactured by Nippon Emulsifier Co., Ltd.) 0 6 parts was mixed and stirred for 60 minutes using a stirrer to prepare a water-based coating composition.

Example 22
80 parts of the acrylic polymer emulsion of Production Example 1, 120 parts of a silicone resin emulsion (WACKER BS45 manufactured by Asahi Kasei Silicone Co., Ltd.), and a surfactant having a HLB of 19.2 (NEWCOL2399S manufactured by Nippon Emulsifier Co., Ltd.) 0 4 parts was mixed and stirred for 60 minutes using a stirrer to prepare an aqueous coating composition.

Example 23
40 parts of the acrylic polymer emulsion of Production Example 1, 160 parts of a silicone resin emulsion (WACKER BS45 manufactured by Asahi Kasei Wacker Silicone Co., Ltd.), and a surfactant having a HLB of 19.2 (NEWCOL2399S manufactured by Nippon Emulsifier Co., Ltd.) 0 2 parts were mixed and stirred for 60 minutes using a stirrer to prepare an aqueous coating composition.

Comparative Examples 1-7 (Table 3)
A water-based coating composition was prepared in the same manner as in Example 1 except that the (meth) acrylic polymer emulsion and the surfactant of the production examples described in Table 3 were used. In the table, Em108 and Em120 are abbreviations for Emulgen 108 (HLB12.1) and Emulgen 120 (HLB15.3) manufactured by Kao Corporation, respectively.

Comparative Examples 8-9 (Table 4)
A water-based coating composition was prepared in the same manner as in Example 1 except that the (meth) acrylic polymer emulsion of the production example described in Table 4 was used.

Reference Examples 1 to 3 (Table 4)
Only (A) component or (B) component described in Table 4 was prepared, and this was made into Reference Examples 1-3.

  Evaluation of physical properties (storage stability, gloss value of coating film, water contact angle (water repellency), water resistance) of each of the aqueous coating compositions of Examples, Comparative Examples and Reference Examples prepared as described above. went. The results are shown in Tables 3-4.

  From the results of Tables 3 to 4, it was found that the water-based coating composition according to the present invention was excellent in storage stability, and the formed coating film had good low glossiness, water repellency and water resistance. Further, from the results of Example 7, the silicone resin water dispersion was obtained in the mixture of (A) and (C) obtained by adding the high HLB surfactant (C) to the acrylic polymer emulsion (A). The storage stability of the aqueous coating composition prepared by mixing with the body (B) is the storage stability of the aqueous coating composition obtained by simultaneously mixing (A), (B) and (C). It was found that it was even better.

  Since the water-based coating composition of the present invention has good storage stability and low gloss, it can form a coating film excellent in water repellency, water resistance, weather resistance, gloss retention, and stain resistance. It is suitably used as a paint in the field.

Claims (6)

(Meth) acrylic polymer emulsion (A) obtained by polymerizing a (meth) acrylic monomer containing 2-15% by mass of a hydroxyl group-containing polymerizable monomer, an aqueous silicone resin dispersion (B), And an aqueous coating composition containing a high HLB surfactant (C) having an HLB of 16 to 20, wherein the high HLB surfactant (C) is added to 100 parts by weight of a (meth) acrylic polymer emulsion (A). 0.2 to 2 parts by mass of the silicone resin aqueous dispersion (B) is dimethylpolysiloxane, diethylpolysiloxane, dipropylpolysiloxane, dibutylpolysiloxane, diisopropylpolysiloxane, dihexylpolysiloxane, dioctylpolysiloxane , Ethyl methyl polysiloxane, methyl propyl polysiloxane, butyl methyl polysiloxane, isop Pills methylpolysiloxane, hexyl methyl polysiloxane, methyl octyl polysiloxane, ethyl propyl polysiloxane emulsion composition der Ru aqueous coating composition individually or in combination of two or more organopolysiloxanes selected from butyl octyl polysiloxane.   The water-based coating composition according to claim 1, wherein the particle diameter of the (meth) acrylic polymer emulsion (A) is 110 to 250 nm.   The water-based coating composition according to claim 1 or 2, wherein the mass ratio of the (meth) acrylic polymer emulsion (A) and the silicone resin aqueous dispersion (B) is in the range of 80 to 20/20 to 80.   The water-based paint composition according to any one of claims 1 to 3, wherein the (meth) acrylic polymer emulsion (A) is formed by emulsion polymerization in the presence of an ultraviolet absorber and / or a light stabilizer. object.   It is a manufacturing method of the water-based coating composition of any one of Claims 1-4, Comprising: 1) The process of forming a (meth) acrylic-type polymer emulsion (A), and 2) (Meth) acrylic-type A method for producing an aqueous coating composition comprising the steps of mixing a polymer emulsion (A), a silicone resin aqueous dispersion (B), and a high HLB surfactant (C) in this order.   It is a manufacturing method of the water-system coating composition of any one of Claims 1-4, Comprising: 1) The process of forming a (meth) acrylic-type polymer emulsion (A), 2) (meth) acrylic-type heavy A step of preparing a mixed solution of the combined emulsion (A) and the high HLB surfactant (C), and 3) silicone in the mixed solution of the (meth) acrylic polymer emulsion (A) and the high HLB surfactant (C). A method for producing an aqueous coating composition comprising the steps of mixing the resin water dispersion (B) in this order.