JP2000290464A - Aqueous dispersion, method for producing the same, and coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aqueous dispersion having high dispersion stability and storage stability without using a silane compound and having high film-forming properties even at a high solid content concentration. SOLUTION: In a system in which inorganic or organic particles are dispersed in an aqueous medium in the presence of a nonionic surfactant, a vinyl monomer is polymerized at a temperature equal to or higher than the cloud point, thereby containing core-shell structure composite particles. Produce an aqueous dispersion. By adjusting the reaction conditions, it is possible to control the formation ratio of the core-shell composite particles / polymer single particles / inorganic or organic particles, and thus the gloss of the coating film. The aqueous dispersion is useful as a coating composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an aqueous dispersion composed of composite particles having an inorganic or organic particle as a core and an organic polymer as a shell, a process for producing the same, and a coating comprising the aqueous dispersion. The present invention relates to a coating composition having high formability and stain resistance and capable of controlling gloss, mechanical properties, and the like.

[0002]

2. Description of the Related Art Colloidal silica is excellent in hardness, mechanical strength, antistatic property, chemical resistance and weather resistance, and organic polymer is excellent in flexibility, adhesion, water resistance and the like. Organic / inorganic composite aqueous compositions are known. For example, an aqueous coating material containing a mixture of a vinyl acetate emulsion, an acrylic emulsion, an acrylic-styrene emulsion, colloidal silica, a water-curable binder, and the like as a main component is known. However, these aqueous coating agents have a small bonding force between the organic polymer and the inorganic substance, and do not have sufficient long-term durability, film forming property, water resistance, and the like. Further, in a coating composition using a binder system of the colloidal silica and an organic polymer as a binder, a large amount of the colloidal silica decreases the film-forming property,
It is difficult to achieve a good balance between the contamination by the colloidal silica and the film forming property at a high level. Furthermore, when a matting agent such as silica or calcium carbonate is used to adjust the gloss of the coating film, the water resistance, weather resistance, and mechanical properties decrease with an increase in the matting agent.

To chemically bond colloidal silica as an inorganic substance and an organic polymer, JP-A-59-7131 is used.
No. 6, JP-A-63-37168 discloses an aqueous resin dispersion obtained by copolymerizing a silane-based monomer and colloidal silica. In this dispersion, a chemical bond is formed between the colloidal silica and the silane monomer, so that the compatibility and affinity between the inorganic substance and the organic polymer are good, and the water resistance, alkali resistance, and stain resistance are excellent. ing. However, the stability of the obtained aqueous dispersion and paint is low, and the coating film is non-uniform, so that the coating film shrinks and has a strong cohesive force, which may cause cracks in the coating film and increase durability. There are difficulties.

Japanese Patent Application Laid-Open No. 9-194208 proposes producing an aqueous dispersion of core-shell composite particles by coupling colloidal silica and organoalkoxysilane and then polymerizing a vinyl monomer. Have been. However, when a colloidal silica having an average particle diameter of 50 nm or less that exhibits good strength, appearance, and transparency as a coating film is used, it is difficult to obtain an aqueous dispersion having a solid content of 40% by weight or more, At a high solids content, the viscosity increases significantly and the film formability is poor. In addition, stable core
In order to obtain shell-like composite particles, it is necessary to use many special silane compounds having a methacryloyl group, which is disadvantageous in cost. Furthermore, the total reaction time is 10 hours or more, and it is not possible to industrially produce aqueous dispersions and binders for paints.

[0005] Furthermore, the conventional method cannot provide stable core-shell composite particles having not only colloidal silica but also inorganic or organic particles as a core and an organic polymer as a shell.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an aqueous dispersion having good dispersion stability and storage stability, a high solid content and a high film-forming property, and a process for producing the same. is there.

Another object of the present invention is to provide an aqueous dispersion having excellent characteristics economically and advantageously without using a special silane compound and a method for producing the same.

Another object of the present invention is to provide an aqueous dispersion mainly composed of core-shell composite particles having inorganic or organic particles as a core and an organic polymer as a shell, and a method for producing the same.

Still another object of the present invention is to provide a method for producing an aqueous dispersion capable of controlling the amount of polymer-only particles produced and the degree of surface coverage of inorganic or organic particles.

Another object of the present invention is to provide a coating composition which can maintain a high level of film forming property, stain resistance, appearance and weather resistance and can form a coating film having high durability.

Still another object of the present invention is to provide a coating composition capable of adjusting the gloss of a coating film without using a matting agent.

[0012]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, in a system in which inorganic or organic particles are dispersed in an aqueous medium in the presence of a nonionic surfactant, When a vinyl monomer is polymerized at a temperature equal to or higher than the cloud point of a nonionic surfactant, the vinyl polymer is effectively bonded to the surface of the inorganic or organic particles, and an aqueous dispersion having high dispersion stability and film formability can be obtained. And completed the present invention.

That is, the aqueous dispersion of the present invention comprises composite particles in which a vinyl polymer is bonded to the surface of inorganic or organic particles directly or via a nonionic surfactant,
The particles are dispersed in an aqueous medium. The inorganic or organic particles may be colloidal silica or pigment. As the nonionic surfactant, a polyoxyalkylene ether or a derivative thereof can be used, and the vinyl polymer is a (meth) acrylic monomer, an aromatic vinyl monomer, a vinyl ester monomer, or the like. Can be formed. In such an aqueous dispersion, the composite particles have an average particle size of 10 μm or less.

The aqueous dispersion polymerizes a vinyl monomer at a temperature higher than the cloud point of the nonionic surfactant in a system in which inorganic or organic particles are dispersed in an aqueous medium in the presence of the nonionic surfactant. Can be manufactured. The present invention also discloses a coating composition containing the aqueous dispersion.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The composite particles constituting the aqueous dispersion of the present invention are composed of inorganic or organic particles and a vinyl polymer bonded to the surface of the inorganic or organic particles directly or via a nonionic surfactant. And are dispersed in an aqueous medium. The composite particles of this dispersion system utilize the fact that a nonionic surfactant is adsorbed on the particle surface at a temperature higher than the cloud point to provide a site for polymerization of vinyl monomers.

In the present invention, fine particles are usually used as the particles.

In the composite particles, the inorganic or organic particles constitute a core, and the polymer which is a vinyl polymer constitutes a shell. In the shell portion of such an aqueous dispersion,
Other nonionic or anionic surfactants may be included.

[Inorganic particles] As the inorganic particles, various functional particles, for example, silica, inorganic pigments, conductors (for example,
Gold, silver, platinum, aluminum or their alloys),
A magnetic material (eg, ferrite) can be used.
These functional particles may be colloidal (for example, colloidal silica).

(Colloidal Silica Particles) The colloidal silica particles (colloidal silica) have an average particle diameter of 5 nm.
Colloids (colloids) of fine particles of silicic anhydride having a thickness of about 1 μm, preferably about 10 to 100 nm can be used. For colloidal silica, JP-A-53-112732, JP-B-57-9051, and JP-A-57-51653 can be used. Publications and the like can be referred to.

The colloidal silica can be prepared and used by a sol-gel method, or a commercially available product can be used. When colloidal silica is prepared by a sol-gel method, Werner Stober et al; J. Colloid and Interface S
ci., 26, 62-69 (1968), Rickey D. Badley et al; Lang.
muir 6, 792-801 (1990), Journal of the Society of Color Materials, 61 [9] 488-493
(1988).

Commercially available colloidal silica is available from Nissan Chemical Co., Ltd. under the name of Snowtex-XL (average particle size 40 to 6).
0 nm), Snowtex-YL (average particle size 50-80)
nm), Snowtex-ZL (average particle size 70-100)
nm), PST-2 (average particle diameter 21 nm), Snowtex 20 (average particle diameter 10 to 20 nm, SiO ₂ / Na ₂ O)
> 57), Snowtex 30 (average particle size 10-20 n)
m, SiO ₂ / Na ₂ O> 50), Snowtex C (average particle size 10-20 nm, SiO ₂ / Na ₂ O> 100),
Snowtex O (average particle size 10-20 nm, SiO ₂
/ Na ₂ O> 500), Snowtex 50 (average particle size 20-30 nm), etc., and Adelaite AT-40 (average particle size 10-2
0 nm, solid content 40% by weight), Adelite AT-50
(Average particle diameter: 20 to 30 nm, solid content: 50% by weight) etc. (Note that SiO ₂ / Na ₂ O indicates the content ratio by weight of silicon dioxide and sodium hydroxide (converted to Na ₂ O), and It is described in). When a commercial product is used, Adelite AT-40, AT-50, Snowtex 40, 50 and the like are preferable.

The colloidal silica is mainly composed of silicon dioxide, and may contain alumina, sodium aluminate and the like as minor components. Further, the colloidal silica may contain an inorganic base (such as sodium hydroxide, potassium hydroxide, lithium hydroxide, or ammonia) or an organic base (such as tetramethylammonium) as a stabilizer.

(Inorganic pigments) As inorganic pigments, white pigments (eg, zinc oxide, lithopone, titanium oxide, etc.), yellow pigments (eg, chrome yellow, nickel titanium yellow, iron oxide yellow, yellow lead oxide, etc.), red pigments (For example,
Iron oxide red, red lead oxide, molybdenum red, etc.), orange pigments (eg, molybdate orange, etc.), green pigments (eg, chrome green, chromium oxide, etc.), blue pigments (eg, navy blue, ultramarine, cobalt blue), Examples include a purple pigment (for example, manganese violet), a black pigment (for example, carbon black such as channel black and furnace black, and black iron oxide).

Further, extenders (eg, calcium carbonate, barium sulfate, aluminum hydroxide, etc.) may be used.

[Organic particles] Organic particles include organic pigments,
Organic polymer particles (for example, silicone resin, polymethyl methacrylate resin, melamine resin, crosslinked styrene resin, etc.) can be used.

(Organic pigments) As organic pigments, azo pigments (for example, yellow pigments such as Hansa Yellow, Benzidine Yellow, Vulcan Fast Yellow and Permanent Yellow, orange pigments such as pyrazolone orange, Vulcan Orange and Permanent Orange, toluidine red,
Permanent red, brilliant fast scarlet, balkan fast red, pyrazolone red, watching red, litho red, lake red, brilliant carmine, lake bordeaux and other red pigments, phthalocyanine pigments (for example, phthalocyanine blue, fast sky blue and other blue) Pigments, green pigments such as phthalocyanine green), lake pigments (eg, red pigments such as rhodamine lake, blue pigments such as methyl violet lake and Victoria Pure Blue lake, and green pigments such as Final Yellow Green)
And the like. In addition, organic pigments such as quinacridone-based, perylene-based, isoindolinone-based, dioxazine-based, and sulene-based pigments may be used.

These inorganic or organic particles may be used alone or in combination of two or more. Usually, colloidal silica and pigments (inorganic or organic pigments) are used as the inorganic or organic particles.

The average particle size of the inorganic or organic particles is 5
μm or less (for example, 5 nm to 1 μm), preferably 10 μm
nm to 0.5 μm, more preferably 20 nm to 0.2
It can be selected from a range of about μm. When the inorganic or organic particles are colloidal silica, the average particle size is 5 to 10
0 nm, preferably about 10 to 80 nm, and more preferably about 10 to 50 nm. In the case of carbon black, the average particle size is 10 to 300 nm, preferably 20 to 100 nm, more preferably 30 to 80 nm.
It is about.

These inorganic or organic particles may be subjected to a surface treatment, if necessary.

[Nonionic surfactant] In the composite particles, a vinyl polymer is bonded to the surface of the inorganic or organic particles directly or via a nonionic surfactant. The inorganic or organic particles are usually negatively charged in an aqueous medium to be dispersed and stabilized. Therefore, in the present invention, after mixing the nonionic surfactant and the inorganic or organic particle dispersion liquid at a temperature lower than the cloud point, the nonionic surfactant is added to the surface of the inorganic or organic particles by adjusting the temperature to the cloud point or higher. Let it adsorb,
Provides a place for the polymerization of vinyl monomers. The surface of the inorganic or organic particles is usually hydrophilic, but the surface of the particles can be made hydrophobic by adsorption of a nonionic surfactant.

In the present invention, the cloud point of a nonionic surfactant is defined as the cloud point of a dispersion in which inorganic or organic particles are dispersed in an aqueous medium in the presence of a nonionic surfactant. Means the temperature at which The cloud point is
Since it is affected by the concentration of the nonionic surfactant and the electrolyte, it can be measured under each reaction condition. The cloud point of the nonionic surfactant is, for example, 0 to 80 ° C., preferably 10 to 80 ° C.
To 70 ° C, more preferably about 20 to 60 ° C.

Examples of nonionic surfactants (dispersants or dispersion stabilizers) include proteins (gelatin, colloidal albumin, casein, lecithin, etc.), sugar derivatives (agar, starch derivatives, etc.) and cellulose derivatives (hydroxymethyl cellulose, etc.). ), Esters of polyhydric alcohols [ethylene glycol monofatty acid esters (for example,
Monoglycol ester of oleic acid, monoglycol ester of stearic acid, etc.), polyethylene glycol monofatty acid ester, propylene glycol monofatty acid ester, glycerin monofatty acid ester (for example,
Monoglyceride, stearic acid, etc.), glycerin difatty acid ester, sucrose fatty acid ester, sorbitan fatty acid ester (trade name span) etc.), synthetic hydrophilic polymer,
For example, polyvinyl alcohol, polyvinyl alcohol modified with a terminal long-chain alkyl group, vinyl polymer [at least one ethylenically unsaturated such as hydroxyalkyl (meth) acrylate, alkyl vinyl ether, vinyl acetate, (meth) acrylamide, diacetone acrylamide, etc. Or copolymer containing a monomer having a group as a constituent element], polyoxyalkylene (polyoxyethylene, polyoxypropylene) or a derivative thereof [polyoxyethylene alkyl ether, polyoxyethylene alkylaryl ether, the fatty acid ester] Alkylene oxide adducts (for example, polyoxyethylene glycerin fatty acid ester, polyoxyethylene sucrose fatty acid ester, polyoxyethylene sorbitan fatty acid ester (trade name Twi) ), Etc.)].
As the dispersant, a graft polymer, a block polymer or a macromer in which an anchor group and a dispersion stabilizing group are separated may be used. These nonionic surfactants can be used alone or in combination of two or more.

When a nonionic surfactant having an unsaturated bond (eg, vinyl, isopropenyl, (meth) acryloyl, etc.) is used, the nonionic surfactant adsorbed on the surface of inorganic or organic particles is polymerized with a vinyl monomer. it can.

Preferred nonionic surfactants include polyoxyethylene alkyl ethers (for example, polyoxyethylene lauryl ether (Emulgen 108, Kao Corporation, cloud point 40 ° C.), polyoxyethylene stearyl ether (Kao Corporation) ), Emulgen 409P, cloud point 5
5 ° C.), polyoxyethylene C _6-20 alkyl ether], polyoxyethylene alkyl phenyl ether [eg, polyoxyethylene octyl phenyl ether,
Polyoxyethylene lauryl phenyl ether, polyoxyethylene nonyl phenyl ether (manufactured by Kao Corporation,
Polyoxyethylene C _6-20 alkyl phenyl ether such as emulgen 909, cloud point 40 ° C.), polyoxyethylene sucrose C _12-20 fatty acid ester, polyoxyethylene sorbitan C _12-20 fatty acid ester, polyoxyalkylene block Copolymers [for example, polyoxyethylene-polyoxypropylene block copolymers (Pluronic L61, manufactured by Asahi Denka Kogyo Co., Ltd., cloud point 24 ° C., Pluronic L-64, cloud point 58 ° C.)], allyl groups, etc. Polyoxyethylene C _6-20 alkylphenyl ether having at least one ethylenically unsaturated group (polymerizable unsaturated group) [for example, 1-allyloxymethyl-2-nonylphenyloxyethanol ethylene oxide adduct (Asahi Denka Industrial Corporation, NE-10, cloud point 40 ° C.).

The hydrophilic-lipophilic balance (HLB) of the nonionic surfactant can be selected in a wide range, for example, about 1 to 30, preferably about 3 to 25, and more preferably about 5 to 20.

The nonionic surfactant is used in an amount of 0.1 to 100 parts by weight of the vinyl polymer described below in terms of solid content.
It is about 1 to 20 parts by weight, preferably about 0.5 to 15 parts by weight, and more preferably about 1 to 10 parts by weight. Note that the nonionic surfactant may be referred to as a first nonionic surfactant.

[Vinyl polymer] The vinyl polymer can be formed from a conventional polymerizable monomer, and may be a homopolymer or a copolymer. The monomer (vinyl monomer) forming the vinyl polymer includes a radical polymerizable monomer having at least one ethylenically unsaturated group, for example, a (meth) acrylic monomer, an aromatic vinyl-based monomer. Monomers and vinyl ester monomers. These monomers can be used alone or in combination of two or more.

As the vinyl monomer, for example, (meth)
Acrylic acid alkyl esters [methyl (meth) acrylate, ethyl (meth) acrylate, n- or i-propyl (meth) acrylate, 2-methyl-2-nitropropyl (meth) acrylate, n-, i-, s- Or t-butyl (meth) acrylate, n- or t-pentyl (meth) acrylate, 3-pentyl (meth) acrylate, 2,2-dimethylbutyl (meth) acrylate, n-hexyl (meth) acrylate, cetyl (meth) A) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 4-methyl-2-propylpentyl (meth) acrylate, n
( _C1-20 alkyl esters of (meth) acrylic acid such as octadecyl (meth) acrylate), cycloalkyl (meth) acrylate [cyclohexyl (meth) acrylate, cyclopentyl (meth) acrylate and the like],
Aralkyl (meth) acrylate [benzyl (meth) acrylate, etc.], polycyclic (meth) acrylate [2-
Isobornyl (meth) acrylate, 2-norbornylmethyl (meth) acrylate, 5-norbornene-2-
Yl-methyl (meth) acrylate, 3-methyl-2-
Norbornylmethyl (meth) acrylate], hydroxyl group-containing (meth) acrylates [hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2,3-dihydroxypropylmethyl-butyl (meth) Methacrylate, etc.), alkoxy or phenoxy group-containing (meth) acrylates [2-methoxyethyl (meth) acrylate,
2-ethoxyethyl (meth) acrylate, 2-methoxymethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethyl carbitol (meth) acrylate, phenoxyethyl (meth) acrylate, etc.), epoxy group-containing (meth ) Acrylates [glycidyl (meth) acrylate, etc.], halogen-containing (meth) acrylates [2,2,2-trifluoroethyl (meth) acrylate, 2,2,2-
Trifluoroethylethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, hexafluoropropyl (meth) acrylate, octafluoropentyl (meth) acrylate, heptadecafluorodecyl (meth) acrylate, etc.], (meth) acrylamides [ For example, (meth) acrylamide, N-methyl (meth) acrylamide, Nn-butyl (meth) acrylamide, Ni-propyl (meth) acrylamide, Nt-butyl (meth) acrylamide, N, N-
Dimethyl (meth) acrylamide, 2- (meth) acrylamide-2-methylpropanesulfonic acid, (meth) acrylamidopropyltrimethylammonium chloride, diacetone (meth) acrylamide, (meth) acryloylmorpholine, N-methylol (meth) acrylamide, etc.] , Alkylaminoalkyl (meth) acrylates [dimethylaminoethyl (meth) acrylate etc.], vinyl cyanides [(meth) acrylonitrile etc.], vinyl esters (eg vinyl acetate etc.),
Aromatic vinyl compounds (for example, styrene, p-chlorostyrene, t-butylstyrene, α-methylstyrene, sodium styrenesulfonate, etc.), a carboxyl group-containing monomer or a salt thereof [(meth) acrylic acid, itaconic acid, Maleic acid, fumaric acid or a salt thereof], a sulfonic acid group-containing monomer or a salt thereof [vinyl sulfonic acid, sodium vinyl sulfonate, sodium allyl sulfonate,
Sodium methallyl sulfonate], unsaturated polycarboxylic acid derivatives (esters such as dimethyl maleate, dibutyl maleate and diethyl fumarate, N-substituted maleimides such as N-phenylmaleimide), N-vinyl polyvalent Carboxylic acid imides [such as N-vinyl succinimide], dienes (eg, butadiene, cyclopentadiene, isoprene), and heterocyclic vinyl monomers (N-vinyl pyrrolidone, N-vinyl oxazolidone, 1-vinyl imidazole, 4-vinyl Pyridine, etc.), N-vinylamides (N-vinylformamide, N-vinyl-N-
Methylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide, etc.), halogen-containing vinyl monomers (vinyl chloride, viridene chloride, etc.), vinyl alkyl ethers (eg, methyl vinyl ether, etc.), olefins ( Ethylene, propylene, 1-butene, isobutene, etc.).
These vinyl monomers can be used alone or in combination of two or more.

Preferred vinyl monomers include (meth) acrylic monomers, aromatic vinyl monomers, vinyl ester monomers and the like. In particular, at least a (meth) acrylic monomer is often used.

The vinyl monomer may be used in combination with a polyfunctional vinyl monomer having two or more unsaturated groups. As the polyfunctional vinyl monomer, for example, divinylbenzene, 4,
4′-isopropylidene diphenylene (meth) acrylate, 1,3-butylene di (meth) acrylate,
1,4-cyclohexylene dimethylene (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, tetramethylene di ( (Meth) acrylate, diisopropylidene glycol di (meth) acrylate, divinyloxymethane, ethylidene di (meth) acrylate, allyl (meth) acrylate, 1,6-di (meth) acrylamidohexane, N, N'-methylenebis (meth) Acrylamide,
N, N- (1,2-dihydroxy) ethylenebis (meth) acrylamide, 2,2-dimethyl-1,3-trimethylenedi (meth) acrylate, phenylethylenedi (meth) acrylate, 2,2,2-trichloroethylidene Di (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, 1,3,5-tri (meth) acryloylhexahydro-s-triazine, Screw (meta)
Acrylamide acetic acid, ethylidine tri (meth) methacrylate, propylidine tri (meth) acrylate, vinyl allyl oxyacetate and the like can be mentioned. These polyfunctional vinyl monomers can be used alone or in combination. Among these polyfunctional vinyl monomers, divinylbenzene, a monomer having two or more (meth) acryloyl groups (such as ethylene glycol di (meth) acrylate)
Is commonly used.

In the above dispersion system, it is preferable that the nonionic surfactant is adsorbed on the surface of the inorganic or organic particles during the polymerization of the vinyl monomer. Therefore, the polymerization temperature of the vinyl monomer is preferably a temperature exceeding the cloud point of the nonionic surfactant, for example, 20 to 110 ° C, preferably 30 to 100 ° C, and more preferably 60 to 10 ° C.
0 ° C., especially about 70 to 90 ° C.

The vinyl monomer can be selected according to the properties required for the coating film (film forming property, glass transition temperature, etc.), and is usually -30 to 80 ° C., preferably −30 to 80 ° C. A vinyl polymer is formed at a temperature of 20 ° C to 50 ° C, particularly about 0 to 50 ° C. In addition, a vinyl monomer having a reactive group such as a hydroxyl group, a carboxyl group, an acid anhydride group, or a glycidyl group may be used to form a crosslinking system.

The ratio between the vinyl polymer and the inorganic or organic particles can be selected according to the film-forming properties and the like. For example, 3 to 500 parts by weight of the inorganic or organic particles per 100 parts by weight of the vinyl polymer.
It is about 10 parts by weight, preferably about 10 to 300 parts by weight, more preferably about 20 to 200 parts by weight (for example, about 30 to 200 parts by weight).

[Aqueous Dispersion] The average particle size of the composite particles composed of such components varies depending on the size of the inorganic or organic particles of the core, and is, for example, 10 μm or less (for example, 10 nm to 10 μm). Preferably 50 nm to 5 μ
m (for example, 80 nm to 5 μm), and more preferably about 0.1 to 1 μm. When the average particle diameter is in the above range, the dispersion stability of the composite particles is high. When the inorganic or organic particles are colloidal silica, the average particle size of the composite particles is 10 to 500 nm, preferably 20 to 300 nm.
(Eg, 20-250 nm), especially 30-200 nm
It is about. In the case of carbon black, the average particle size is 10 nm to 1 μm, preferably 30 nm to 0.5 μm.
μm, and more preferably about 50 nm to 0.3 μm.

The ratio of the above components is, for example, 0.1 to 2 parts by weight of the nonionic surfactant per 100 parts by weight of the vinyl polymer.
0 parts by weight (for example, 0.5 to 10 parts by weight), 3 to 500 parts by weight of inorganic or organic particles (for example, 100 to 500 parts by weight)
(Parts by weight).

In the aqueous dispersion, not all of the dispersed particles need to be the core-shell composite particles, and the core-shell composite particles and at least one type of particles selected from vinyl polymer particles and inorganic or organic particles. May be used. In a preferred aqueous dispersion, 80% by weight or more of the particles are composed of composite particles having a core-shell structure in which inorganic or organic particles are used as a core and a vinyl polymer is used as a shell.

[Production Method of Aqueous Dispersion] The aqueous dispersion of the present invention is prepared by dispersing inorganic or organic particles in an aqueous medium in the presence of a nonionic surfactant (first nonionic surfactant). It can be obtained by polymerizing a vinyl monomer at a temperature higher than the cloud point. In particular, after mixing the first nonionic surfactant and the inorganic or organic particle dispersion at a temperature lower than the cloud point, the temperature is raised to a temperature higher than the cloud point, and the first nonionic surfactant is added to the surface of the inorganic or organic particles. By adsorbing the agent and polymerizing the vinyl monomer, composite particles in which inorganic or organic particles and a vinyl polymer are effectively bonded can be obtained.

In the above dispersion system, as the first nonionic surfactant is adsorbed on the surface of the inorganic or organic particles, or as the polymerization of the vinyl monomer proceeds, the inorganic or organic particles become hydrophobic and the dispersion stability decreases. To form a cohesive gel. Therefore, a second nonionic surfactant may be added to the reaction system in order to stabilize the dispersion of the hydrophobic or inorganic particles in an aqueous medium. The second nonionic surfactant may be added at the beginning of mixing, or may be added at the time of temperature rise, at the beginning of polymerization, or after the polymerization. Preferably, after reaching a temperature equal to or higher than the cloud point of the first nonionic surfactant,
It is preferable to add a nonionic surfactant.

The cloud point of the second nonionic surfactant is
In order to stabilize the dispersion of the inorganic or organic particles to which the nonionic surfactant is adsorbed, the nonionic surfactant often exceeds the cloud point of the first nonionic surfactant. Furthermore, in the process of polymerization of the vinyl monomer, in order to stabilize the inorganic or organic particles,
It preferably has a cloud point above the polymerization temperature. The second nonionic surfactant is oriented on the surface of the hydrophobicized inorganic or organic particles, stabilizes the inorganic or organic particles, and further, together with the first nonionic surfactant, acts as a polymerization site for the vinyl monomer. provide.

The amount of the second nonionic surfactant used is preferably equal to or less than the critical micelle concentration (CMC) in order to prevent micelles from forming vinyl polymer single particles. In conversion, inorganic or organic particles 10
It is often 0.01 to 5 parts by weight, preferably 0.1 to 3 parts by weight, and more preferably about 0.1 to 2 parts by weight with respect to 0 parts by weight.

Further, an anionic surfactant generally used for emulsion polymerization may be used for stabilizing the dispersion. In addition, in order to effectively adsorb the first nonionic surfactant on the surface of the inorganic or organic particles, after adsorbing the first nonionic surfactant on the surface of the inorganic or organic particles, the anionic surfactant is added. Is preferred. For example, the anionic surfactant may be added after the nonionic surfactant is uniformly adsorbed on the inorganic or organic particles, or after the vinyl monomer has been polymerized to produce stabilized seed-like composite particles. . As described above, since the inorganic or organic particles are usually negatively charged in an aqueous medium, the adsorption efficiency with an anionic surfactant is expected to be low, but the anionic surfactant having a negative charge is expected. The agent may form micelles alone for inorganic or organic particles that are negatively charged. Therefore, if an anionic surfactant is added at the beginning of mixing, a large number of polymer-only particles may be generated.

In the present invention, the vinyl monomer can be polymerized by various methods which can be polymerized in the dispersion system. A preferred polymerization method is an emulsion polymerization method in which a vinyl monomer is polymerized in an aqueous medium (particularly, water). In the emulsion polymerization method, a method in which a vinyl monomer is continuously or stepwise charged into a reaction system is preferable. If monomers are charged into a system in which inorganic or organic particles are dispersed in the presence of a nonionic surfactant, the possibility of forming core-shell composite particles may be reduced. This seems to be because the adsorbed nonionic surfactant is dissolved in the monomer oil droplets, and the amount of nonionic surfactant adsorbed on the surface of the inorganic or organic particles is reduced. After the stable particles are generated as a seed, the vinyl monomer may be charged at once. When a monomer is added to the reaction system, the composition of the monomer may be the same or may be changed.

As the polymerization initiator, a peroxide (for example,
Hydrogen peroxide, etc., persulfates (eg, potassium persulfate, ammonium persulfate), aqueous azo compounds and redox polymerization initiators can be used.

In the polymerization of the present invention, in order to adjust the molecular weight of the polymer, a chain transfer agent such as an organic peroxide soluble in a vinyl monomer, an organic azo compound, a halogenated hydrocarbon (such as carbon tetrachloride, etc.) ), Mercaptans, thiols, and the like. The amount of the chain transfer agent used is, for example, 5% by weight or less based on the vinyl monomer.

If necessary, a pH adjuster (for example, acid (sulfuric acid, hydrochloric acid, etc.), ammonia, amine, etc.) may be added to the aqueous solution after the polymerization process or after completion of the reaction in order to enhance the dispersion stability of the inorganic or organic particles. It may be added to the dispersion. The pH of the polymerization system or the aqueous dispersion may be adjusted to, for example, about pH 7 to 9 (for example, 7.5 to 8.5).

In the present invention, the ratio of core-shell composite particles / vinyl polymer particles / inorganic or organic particles can be adjusted by adjusting the cloud point, critical micelle concentration (CMC) or the amount of nonionic surfactant used in combination. Can be arbitrarily controlled.

That is, when a vinyl monomer is polymerized at a temperature higher than the cloud point of a nonionic surfactant in a system in which inorganic or organic particles are dispersed in an aqueous medium, at least the core
An aqueous dispersion mainly composed of composite particles having a shell structure can be obtained. Further, when the vinyl monomer is polymerized at a nonionic surfactant concentration lower than the critical micelle concentration (CMC) (a), the nonionic surfactant can be effectively adsorbed on inorganic or organic particles, and the core-shell structure can be obtained. Can be obtained. On the other hand, when the nonionic surfactant concentration is equal to or higher than the critical micelle concentration (b), micelles may be formed as a polymerization site for vinyl monomers, and vinyl polymer particles may be formed.

Further, the amount of the nonionic surfactant used is
When the amount is less than the saturated adsorption amount to the inorganic or organic particles (1), ordinary inorganic or organic particles are generated. An aqueous dispersion can be obtained.

As described above, in the present invention in which polymerization is performed at a temperature equal to or higher than the cloud point of the nonionic surfactant, by adjusting the type and concentration of the nonionic surfactant, the core-shell composite particles / vinyl polymer particles / The ratio of inorganic or organic particles can be controlled. More specifically,
It is as follows.

(A-1) When the concentration of the nonionic surfactant is
When the concentration is less than the critical micelle concentration (CMC) and less than the saturated adsorption amount for inorganic or organic particles, an aqueous dispersion composed of a mixture of composite particles having a core-shell structure / inorganic or organic particles is obtained.

(A-2) When the concentration of the nonionic surfactant is
When the concentration is less than the critical micelle concentration and is equal to or higher than the saturated adsorption amount for inorganic or organic particles, an aqueous dispersion containing core-shell composite particles as a main component can be obtained.

When (b-1) the concentration of the nonionic surfactant is not less than the critical micelle concentration and less than the saturated adsorption amount to inorganic or organic particles, the composite particles / vinyl polymer particles / inorganic or organic particles An aqueous dispersion composed of a ternary system of particles can be obtained.

When (b-2) the concentration of the nonionic surfactant is not less than the critical micelle concentration and not less than the saturated adsorption amount to inorganic or organic particles, it is composed of a mixture of composite particles / vinyl polymer particles. Aqueous dispersion can be obtained.

In the present specification, the critical micelle concentration (CMC) means a concentration at which micelles are formed in an aqueous phase when a nonionic surfactant is added in the presence of inorganic or organic particles. The critical micelle concentration varies depending on the content of inorganic or organic particles, the electrolyte concentration, etc., and from the relationship between the surfactant concentration and the surface tension, an index of the apparent critical micelle concentration at which the surface tension becomes a minimum value. It can be. For example, the presence of these components increases the critical micelle concentration of the nonionic surfactant compared to the case where no inorganic or organic particles or electrolyte is present. The saturated adsorption amount can be measured in advance by a conventional method. In the case of inorganic or organic particles having an average particle size of 50 nm or less, based on 100 parts by weight of inorganic or organic particles in terms of solid content,
It is often about 0.5 to 5 parts by weight (for example, 1 to 2 parts by weight).

The solid concentration of the aqueous dispersion can be selected according to the use and the like, and is, for example, about 10 to 60% by weight, preferably about 30 to 55% by weight, and particularly about 45 to 55% by weight.

The aqueous dispersion obtained by such a method is
Even if the content of the inorganic or organic particles is 50% by weight, it is possible to form a coating film excellent in high film forming property, stainability, heat resistance and the like. Further, the ratio of the core-shell composite particles / vinyl polymer particles / inorganic or organic particles can be controlled, and a high gloss coating film or a matte coating film can be formed. for that reason,
The composition composed of the aqueous dispersion of the present invention is useful as a film forming material (coating agent), particularly as a coating composition. In the aqueous dispersion, the ratio between the composite particles and the inorganic or organic particles is determined by the following formula: composite particles / inorganic or organic particles =
When it is changed in the range of 100/0 to 50/50 (weight ratio in terms of solid content), the gloss (gloss) at an incident angle of 60 ° is in the range of about 85 to 3 without using a matting agent such as silica. Can be adjusted.

In the coating composition (water-based coating composition) of the present invention, various components usually used in water-based coatings, for example, dispersants, wetting agents, thickeners, plasticizers, surface conditioners, defoamers ,
Viscosity modifiers, flame retardants, antistatic agents, water-soluble organic solvents and the like can be used. In addition, the coating composition may contain a pigment if necessary. As the above-mentioned pigments, the above-mentioned inorganic or organic pigments (for example, coloring pigments such as titanium dioxide and phthalocyanine blue, extenders such as calcium carbonate and barium sulfate) may be used, and luster such as aluminum powder and mica flakes may be used. An agent may be used. The pigment weight concentration (PWC) in the coating composition is usually expressed in terms of solid content,
It is about 1 to 70% by weight, preferably about 10 to 65% by weight, and more preferably about 20 to 60% by weight. When the solid content is less than 1% by weight, the concealing property is reduced. When the solids content is more than 70% by weight, the gloss of the coating film is reduced, the viscosity is increased, and the water resistance and mechanical strength are apt to be reduced.

Among the above-mentioned coating compositions, the coating composition containing the composite particles (which also function as a binder) as a main component (80% by weight or more) is based on 100 parts by weight of the vinyl monomer, and is composed of inorganic or organic particles. 3 to 500 parts by weight (preferably 5 to 5 parts by weight)
0 to 500 parts by weight, more preferably 100 to 500 parts by weight) having a high film forming property in a wide range,
Has excellent stain resistance and flame retardancy. In particular, a coating composition having a high content of inorganic or organic particles can exhibit high flame retardancy without using a flame retardant.

If necessary, a water-soluble or water-dispersible binder resin, a crosslinking agent, a curing agent, a crosslinking or curing assistant, etc. may be added to the coating composition of the present invention. When the coating composition of the present invention is applied to a substrate by a conventional method and dried or cured, a coating film having high durability can be formed.

[0070]

According to the present invention, since the aqueous dispersion contains the composite particles (particularly, core-shell composite particles having inorganic or organic particles as a core and an organic polymer as a shell), dispersion stability and storage stability are improved. Even if the solid content is high, the film formability can be enhanced. Further, an aqueous dispersion having excellent characteristics can be obtained economically without using a special silane compound.

In the coating composition of the present invention, a film-forming property and
Stain resistance and weather resistance, which could not be achieved conventionally as a water-based paint, can be maintained at a high level, and a coating film having high water resistance, weather resistance, and high durability can be formed. In addition, a composition having a high composition ratio of inorganic or organic particles can greatly improve heat resistance and flame retardancy while maintaining high film formability. Furthermore, the amount of vinyl polymer particles produced and the degree of surface coverage of inorganic or organic particles can be controlled, and the composition ratio of composite particles / vinyl polymer particles / inorganic or organic particles can be adjusted. Therefore, the gloss of the coating film can be adjusted without using a matting agent.

[0072]

The present invention will be described in more detail based on Synthesis Examples, Examples and Comparative Examples, but the present invention is not limited by these Examples.

Synthesis Example 1 Distilled water was placed in a 1000 mL glass four-necked flask equipped with a stirrer, thermometer, dropping funnel and reflux condenser.
0 g and colloidal silica (Adelite AT-50, manufactured by Asahi Denka Kogyo KK, solid content 50% by weight, average particle size 2)
0 to 30 nm) and a first nonionic surfactant (NE-10, manufactured by Asahi Denka Kogyo KK) under a nitrogen stream.
3.0 g, cloud point 40 ° C., reactivity). After adjusting the 2N-H ₂ SO ₄ at pH8~8.5, 7
The temperature was raised to 0 ° C. 0.6 g of ammonium persulfate was added, and methyl methacrylate (MMA) / n-butyl acrylate (n-BA) / methacrylic acid (MAA) = 49/5.
5 g of a vinyl monomer of 0/1 (weight ratio) was added dropwise for 10 minutes and left for 60 minutes. Further, a second nonionic surfactant (manufactured by Kao Corporation, Emulgen 840S, solid content 70%)
Weight%, cloud point 100 ° C. or higher) and 2.1 g.
At 95 ° C., 95 g of a vinyl monomer of MMA / n-BA / MAA = 49/50/1 (weight ratio) was added dropwise over 4 hours. The reaction temperature was maintained at 70 ° C., and after the completion of the dropwise addition, the mixture was further maintained at 70 ° C. for 1 hour and stirring was continued. After that, it is cooled and 25% by weight
The pH was adjusted to 8.5 with aqueous ammonia to obtain 402 g of a composite fine particle dispersion (yield 98%, solid content 50% by weight, average particle diameter 81 nm).

Synthesis Example 2 Distilled water was placed in a 1000 mL four-neck glass flask equipped with a stirrer, thermometer, dropping funnel and reflux condenser.
0 g and colloidal silica (manufactured by Nissan Chemical Industries, Ltd., Snowtex 50, solid content 50% by weight, average particle size 20 to
300 g), a first nonionic surfactant (NE-10, cloud point 40 ° C., reactivity, manufactured by Asahi Denka Kogyo KK), and a second surfactant (Kao Corporation) under a nitrogen stream. Made,
Emulgen 840S, solid content 70% by weight, cloud point 100 ° C
4.5 g and 2.5 g, respectively, were added with stirring. After adjusting the 2N-H ₂ SO ₄ at PH8～8.5, the temperature was raised to 70 ° C.. 0.6 g of ammonium persulfate was added, and further, MMA / n-BA / styrene (St)
10 g of a vinyl monomer having a ratio of / MAA = 29/50/20/1 (weight ratio) was dropped for 10 minutes, and left for 60 minutes. Then, an anionic surfactant (manufactured by Kao Corporation, Emar 20)
C, 25% by weight of solid content) and then adding 2.0 g of MMA /
90 g of vinyl monomer having n-BA / St / MAA = 29/50/20/1 (weight ratio) was added dropwise at 70 ° C. for 4 hours. The reaction temperature was maintained at 70 ° C., and after completion of the dropwise addition, the temperature was further maintained at 70 ° C. for 1 hour, and stirring was continued. Then cool down,
The pH was adjusted to 8.5 with 25% by weight of aqueous ammonia, and 501 g of a composite fine particle dispersion (yield 98%, solid content 50% by weight,
The average particle diameter was 66 nm.

Synthesis Example 3 [Composite Particles / Polymer Particles] Distilled water 10 was placed in a 1000 mL glass four-necked flask equipped with a stirrer, thermometer, dropping funnel and reflux condenser.
0 g, colloidal silica (Adelite AT-50, manufactured by Asahi Denka Kogyo KK), solid content 50% by weight, average particle size 20 to
30 g) and a first nonionic surfactant (Pluronic L-, manufactured by Asahi Denka Kogyo KK) under a nitrogen stream.
64, cloud point 58 ° C.), second surfactant (Kao Corporation)
Emulgen 840S, solid content 70% by weight, cloud point 10
3.0 g and 6.2 g, respectively, were added with stirring. After adjusting the 2N-H ₂ SO ₄ at PH8～8.5, the temperature was raised to 70 ° C.. 0.6 g of ammonium persulfate
And MMA / n-BA / MAA = 49/5
10 g of 0/1 (weight ratio) vinyl monomer was added dropwise for 10 minutes and left for 60 minutes. Thereafter, an anionic surfactant (manufactured by Kao Corporation, Emar 20C, solid content 25% by weight)
After adding 2.0 g, MMA / n-BA / MAA = 49
90 g of a / 50/1 (weight ratio) vinyl monomer was added dropwise at 70 ° C. over 4 hours. The reaction temperature was maintained at 70 ° C., and after completion of the dropwise addition, the temperature was further maintained at 70 ° C. for 1 hour, and stirring was continued. Thereafter, the mixture was cooled and adjusted to pH 8.5 with 25% by weight aqueous ammonia to obtain 400 g of an aqueous dispersion (yield 98%, solid content 50% by weight, average particle diameter 69 nm).

Synthesis Example 4 [Composite Particles / Colloidal Silica Particles] Distilled water 10 was placed in a 1000 mL glass four-necked flask equipped with a stirrer, thermometer, dropping funnel, and reflux condenser.
0 g, colloidal silica (manufactured by Nissan Chemical Industries, Ltd., Snowtex 50, solid content 50% by weight, average particle size 20 to 30)
200 g), and 0.8 g of a nonionic surfactant (Pluronic L-61, manufactured by Asahi Denka Kogyo KK, cloud point 24 ° C.) was added thereto with stirring under a nitrogen stream. 2N-H ₂
After adjusting the pH to 8 to 8.5 with SO ₄ , the temperature was raised to 70 ° C. 0.6 g of ammonium persulfate was added and MM
A / n-BA / 2-ethylhexyl acrylate (2-E
10 g of a vinyl monomer (HA) / MAA = 49/20/30/1 (weight ratio) was added dropwise for 10 minutes, and left for 60 minutes. Thereafter, 1.5 g of an anionic surfactant (Emaal 20C, manufactured by Kao Corporation, solid content: 25% by weight) was added.
At a temperature of 70 ° C., MMA / n-BA / 2-EHA / MAA =
90 g of vinyl monomer of 49/20/30/1 (weight ratio)
Was added dropwise over 4 hours. Maintaining the reaction temperature at 70 ° C.,
After completion of the dropwise addition, the mixture was further kept at 70 ° C. for 1 hour and stirring was continued. Thereafter, the mixture is cooled and adjusted to pH 25 with 25% by weight aqueous ammonia.
The mixture was adjusted to 8.5 to obtain 399 g of an aqueous dispersion (yield 98%, solid content 50% by weight, average particle diameter 90 nm).

Synthesis Example 5 [Composite Particles / Polymer Particles / Colloidal Silica Particles] Distilled water was added to a 1000 mL glass four-necked flask equipped with a stirrer, thermometer, dropping funnel and reflux condenser.
0 g, colloidal silica (manufactured by Nissan Chemical Industries, Ltd., Snowtex 40, solid content 40% by weight, average particle size 10 to 20)
nm), and a first nonionic surfactant (NE-10, cloud point 40, manufactured by Asahi Denka Kogyo KK) under a nitrogen stream.
° C, reactivity), second nonionic surfactant (Kao Corporation)
EMULGEN 840S, cloud point 100 ° C or higher, solid content 7
0.8 wt.% And 6.2 g., Respectively, with stirring. After adjusting the 2N-H ₂ SO ₄ at PH8～8.5, the temperature was raised to 70 ° C.. 0.6 g of ammonium persulfate
And further, MMA / n-BA / St / MAA =
5 g of a 29/50/20/1 (weight ratio) vinyl monomer was added dropwise over 10 minutes and left for 60 minutes. Thereafter, 1.5 g of an anionic surfactant (Emaal 20C, solid content 25% by weight, manufactured by Kao Corporation) was added, and then MMA / n-B was added.
95 g of a vinyl monomer having A / St / MAA = 29/50/20/1 (weight ratio) was added dropwise at 70 ° C. over 4 hours.
The reaction temperature was maintained at 70 ° C.
And kept stirring for 1 hour. Thereafter, the mixture was cooled and adjusted to pH 8.5 with 25% by weight aqueous ammonia to obtain 399 g of an aqueous dispersion (yield 98%, solid content 50% by weight, average particle size 82 nm).

Synthesis Examples 6 to 8 Using the components shown in Table 1, aqueous dispersions were obtained in the same manner as in the above Synthesis Examples.

Synthesis Example 9 In a 500 mL steel beaker, 240 g of distilled water, and a first nonionic surfactant (NE-, manufactured by Asahi Denka Kogyo KK)
10, a cloud point of 40 ° C., reactivity), 2.4 g of a second nonionic surfactant (Emulgen 840S, manufactured by Kao Corporation, solid content of 70% by weight, cloud point of 100 ° C. or higher), 1.2 g each
g, and 0.24 g of an antifoaming agent (manufactured by San Nopco Co., Ltd., Nopco 8034) is added. While stirring at 1000 rpm, titanium dioxide (manufactured by Teica Co., Ltd., JR-60) is added.
3) While gradually adding 240 g, use a disper,
Stirring was performed at 3000 rpm for 15 minutes to obtain a white mill base.

403.2 g of the white mill base was equipped with a stirrer, a thermometer, a dropping funnel and a reflux condenser.
Put into a 00 mL four-necked flask and add 50 g of distilled water
Was added and the temperature was raised to 70 ° C. under a nitrogen stream. 0.3 g of ammonium persulfate was added, and MMA / n-BA /
5 g of vinyl monomer having MAA = 49/50/1 (weight ratio)
Was dropped over 10 minutes and left for 60 minutes. afterwards,
Anionic surfactant (manufactured by Kao Corporation, Emar 20C,
After adding 0.4 g of solid content 25% by weight, MMA / n-
95 g of a vinyl monomer of BA / MAA = 49/50/1 (weight ratio) was added dropwise at 70 ° C. over 4 hours. After completion of the dropwise addition, the temperature was further maintained at 70 ° C. for 1 hour, and stirring was continued. Thereafter, the mixture was cooled and adjusted to pH 8.5 with 25% by weight aqueous ammonia to obtain 500 g of an aqueous dispersion (yield: 99%, solid content: 50% by weight, average particle diameter: 305 nm).

Synthesis Example 10 Using the components shown in Table 1, an aqueous dispersion was obtained in the same manner as in the above Synthesis Example.

Synthesis Example 11 180 g of distilled water was placed in a 500 mL steel beaker, and a first nonionic surfactant (NE-, manufactured by Asahi Denka Kogyo KK)
10, a cloud point of 40 ° C., reactivity), 5.0 g of a second nonionic surfactant (Emulgen 840S, manufactured by Kao Corporation, solid content of 70% by weight, cloud point of 100 ° C. or higher), 2.5 g each
g, and a wetting agent (manufactured by San Nopco Co., Ltd., Modicol L, nonionic activator, solid content 100% by weight) 3.0
g, antifoaming agent (San Nopco Co., Ltd., Nopco 8034)
While adding 0.3 g, and gradually adding 120 g of quinacridone red (manufactured by Dainichi Seika Kogyo Co., Ltd., Chromofine Red 6820) while stirring at 1000 rpm, 200 g of glass beads is further added, and the number of rotation is 3 with a disper.
Stirring was performed at 000 rpm for 15 minutes.

207.2 g of the mixture obtained above was equipped with a stirrer, thermometer, dropping funnel and reflux condenser.
The mixture was placed in a 00 mL glass four-necked flask, further added with 100 g of distilled water, and heated to 70 ° C. under a nitrogen stream.
0.3 g of ammonium persulfate was added and MMA /
5 g of vinyl monomer of n-BA / MAA = 49/50/1 (weight ratio) was added dropwise over 10 minutes, and left for 60 minutes. Then, after adding 0.4 g of an anionic surfactant (manufactured by Kao Corporation, Emal 20C, solid content 25% by weight),
MMA / n-BA / MAA = 49/50/1 (weight ratio)
Of vinyl monomer was added dropwise at 70 ° C. over 4 hours. After completion of the dropwise addition, the temperature was further maintained at 70 ° C. for 1 hour, and stirring was continued. After cooling, the pH is adjusted with 25% by weight aqueous ammonia.
The mixture was adjusted to 8.5 to obtain 403 g of an aqueous dispersion (yield: 99%, solid content: 45% by weight, average particle diameter: 283 nm).

Comparative Synthesis Example 1 Colloidal silica (Nissan Chemical Industries, Inc., Snowtex 50, solid content 50 wt.) Was placed in a 1000 mL glass four-necked flask equipped with a stirrer, thermometer, reflux condenser, and dropping funnel. %, Average particle diameter 20 to 30 nm), 200 g, non-ionic surfactant (manufactured by Kao Corporation, Emulgen 840S, solid content 70% by weight, cloud point 100 ° C. or higher) under a nitrogen stream.
25 g were added with stirring. PH in 2N-H ₂ SO ₄
After adjusting to 8 to 8.5, the temperature was raised to 70 ° C. 0.6 g of ammonium persulfate was added and further MMA / n-BA
/ MAA = 49/50/1 (weight ratio) vinyl monomer 5
g was added dropwise for 10 minutes and then for 60 minutes. Thereafter, 2.0 g of an anionic surfactant (manufactured by Kao Corporation, Emar 20C, solid content 25% by weight) was added, and MMA / n-BA / M was added.
95 g of vinyl monomer having AA = 49/50/1 (weight ratio)
Was added dropwise over 4 hours. The reaction temperature was maintained at 70 ° C., and after completion of the dropwise addition, the temperature was further maintained at 70 ° C. for 1 hour, and stirring was continued.
Thereafter, the mixture was cooled and adjusted to pH 8.5 with 25% by weight aqueous ammonia.
And 400 g of an aqueous dispersion (yield 98%, solid content 5
0% by weight and an average particle diameter of 98 nm).

Comparative Synthesis Example 2 A 1000 mL glass four-necked flask equipped with a stirrer, a thermometer, a dropping funnel, and a reflux condenser was charged with colloidal silica (Snowtex 40, Nissan Chemical Co., Ltd., solid content 40 wt.). %, Average particle diameter 20 to 30 nm), 16 g of an anionic surfactant (Emaal 20C, manufactured by Kao Corporation, solid content 25% by weight), and 135 g of distilled water.
It was stirred and adjusted to pH7.5 with -H ₂ SO _4. After the temperature was raised to 60 ° C. in a nitrogen stream, 10 g of 3-methacryloyloxypropyltrimethoxysilane was added, and the mixture was stirred for 4 hours. Thereafter, 0.5 g of ammonium persulfate and 0.2 g of sodium sulfite were added, and MMA / n-BA /
MAA = 49/50/1 (weight ratio) vinyl monomer 10
0 g was added dropwise over 4 hours. Reaction temperature during dropping is 65
C. and the stirring was continued for 1 hour after the completion of the dropwise addition. Thereafter, the mixture was cooled and adjusted to pH 8.5 with 25% by weight of aqueous ammonia to obtain 500 g of a composite fine particle dispersion (yield 98%, solid content 40% by weight, average particle size 51 nm).

Comparative Synthesis Example 3 A 1000 mL glass four-necked flask equipped with a stirrer, a thermometer, a dropping funnel and a reflux condenser was charged with an anionic surfactant (Emal 20C, manufactured by Kao Corporation, solid content 25% by weight). ) 12 g, colloidal silica (manufactured by Nissan Chemical Industries, Ltd.,
333 g of Snowtex 30, solid content 30% by weight) and 65 g of distilled water were added and stirred. Under a nitrogen stream,
After the temperature was raised to 60 ° C., 0.5 g of ammonium persulfate and 0.2 g of sodium bisulfite were added, and MMA / n-BA /
100 g of a vinyl monomer of MAA / γ-methacryloyloxypropyltrimethoxysilane = 49 / 49.5 / 1 / 0.5 (weight ratio) was added dropwise over 3 hours. The reaction temperature during the dropwise addition was kept in the range of 60 to 70 ° C., and stirring was continued at the same temperature for 2 hours after the completion of the dropwise addition. Then cool, 2
The pH was adjusted to 8.5 with 5% by weight aqueous ammonia, and 508 g of a composite fine particle dispersion (solid content: 39% by weight, average particle size: 7%)
6 nm).

[Proportions of Composite Particles, Polymer Particles, and Colloidal Silica Particles] The aqueous dispersions of Synthesis Examples 1 to 5 and Comparative Synthesis Example 3 were analyzed with a transmission electron microscope.

First, the aqueous dispersion of the sample was diluted 10 times with distilled water, and the diluted solution was diluted with a mesh Cu having a carbon film.
A small amount was dried on a 200A using a spatula and dried. The dried film was observed with a transmission electron microscope TEM (JEM1220, manufactured by JEOL Datum Co., Ltd.). Under the conditions of an acceleration voltage of 100 kv and a magnification of 20,000, about 200 samples were observed for one sample, and the core-shell type composite particles /
The number ratio of polymer alone particles / colloidal silica particles was calculated.

In the aqueous dispersion obtained in Comparative Synthesis Example 3, the number ratio of core-shell type composite particles / polymer single particles / colloidal silica particles was 12/25/6.
It was 3.

[0090]

[Table 1]

From Table 1, the aqueous dispersions of Synthesis Examples 1 and 2 are
Less polymer alone particles and colloidal silica particles,
It was an aqueous dispersion composed of core-shell type composite particles. The aqueous dispersion of Synthesis Example 3 was composed of composite particles having a core-shell structure and single polymer particles. Further, the aqueous dispersion of Synthesis Example 4 includes a composite particle having a core-shell structure,
And colloidal silica particles. The aqueous dispersion of Synthesis Example 5 was composed of a three-component system of core-shell structure composite particles / polymer single particles / colloidal silica particles. From these synthesis examples, in the present invention, the above three components can be arbitrarily adjusted by adjusting the synthesis conditions and the type of nonionic surfactant.

[Storage Stability] Synthesis Examples 1-2 and 10-1
1. The aqueous dispersion of Comparative Synthesis Example 1 was stored at room temperature for 3 months and stored at a temperature of 50 ° C. for 10 days to examine accelerated storage stability. Table 2 shows the results.

[0093]

[Table 2]

The aqueous dispersions of Synthesis Examples 1-2 and 10-11 exhibited good storage stability with no increase in viscosity and no change in appearance even in storage tests at room temperature and accelerated tests at 50 ° C. . On the other hand, in the comparative synthesis examples, a tendency to hate was observed, probably due to the free silanol compound.
In the accelerated test at ℃, a remarkable thickening was observed.

[Coating Composition] Example 1 10.8 distilled water was placed in a 500 mL steel beaker.
g, thickener (Asahi Denka Kogyo KK, UH420, solid content 6% by weight) 5.0 g, dispersant (Kao Corp., Demol EP) 4.0 g, wetting agent (Kao Corp.) , Emulgen L
-40) (1.0 g) and 0.8 g of an antifoaming agent (San Nopco Co., Ltd., Nopco 8034) were added, and while stirring at 1000 rpm, titanium dioxide (Taika Co., Ltd., JR-60) was added.
3) 80 g was gradually added, and the mixture was stirred at 3000 rpm for 15 minutes using a disper. Thereafter, 200 g of the aqueous dispersion (emulsion) of Synthesis Example 1 was gradually added at 1,000 rpm, and 60 g of distilled water was further added, followed by stirring for 5 minutes. Next, 12 g of a film-forming auxiliary (butyl acetate di-euxole, manufactured by Osaka Organic Chemical Industry Co., Ltd.)
Was added and stirring was continued for another 5 minutes to obtain a white paint.

Examples 2 to 5 In the proportions shown in Table 3, coating compositions were obtained in the same manner as described above.

Example 6 10.8 g of distilled water was placed in a 500 mL steel beaker.
Defoamer (San Nopco Co., Ltd., Nopco 8034) 0.4
g, and stirred at 1000 rpm, while
Of an aqueous dispersion (emulsion) and 160 g of a normal acrylic emulsion (G-25, 50% by weight, manufactured by Mizutani Paint Co., Ltd.). Then, distilled water 60
g and a thickener (UH420, manufactured by Asahi Denka Kogyo Co., Ltd., solid content 6% by weight) were added, and the mixture was stirred for about 10 minutes.
Further, 12 g of a film-forming aid (butyl acetate di-euxole, manufactured by Osaka Organic Chemical Industry Co., Ltd.) was added, and stirring was continued for 5 minutes to obtain a white paint.

Example 7 10.8 g of distilled water was placed in a 500 mL steel beaker.
Defoamer (San Nopco Co., Ltd., Nopco 8034) 0.4
g, and stirred at 1000 rpm, while
200 g of the aqueous dispersion (emulsion) of Example 1 and 180 g of the aqueous dispersion (emulsion) of Synthesis Example 6 were added. continue,
60 g of distilled water and a thickener (UH42 of Asahi Denka Kogyo KK)
(0, solid content: 6% by weight) and stirred for about 10 minutes. Furthermore, a film forming aid (Osaka Organic Chemical Industry Co., Ltd.)
12 g of butyl acetate di-euxole), and stirring was continued to obtain a white paint.

Comparative Example 1 A white paint was obtained by using 200 g of an acrylic emulsion (G-25, solid content of 50% by weight, manufactured by Mizutani Paint Co.) instead of 200 g of the aqueous dispersion of Synthesis Example 1. That is, 10.8 g of distilled water was placed in a 500 mL still beaker,
5.0 g of thickener (6% by weight, UH-420), 4.0 g of dispersant (Demol EP), 1.0 g of wetting agent (Emulgen L40), 0.8 g of antifoaming agent (manufactured by San Nopco Co., Ltd.)
Nopco 8034) and 80 g of titanium dioxide (JR-603) was gradually added while stirring at 1000 rpm with a disper. After the number of revolutions was set to 3000 rpm, stirring was continued for 15 minutes. After that, the rotation speed is 1000r
After that, 200 g of an emulsion (G-25, solid content 50% by weight, manufactured by Mizutani Paint) was added. Further, 150 g of colloidal silica (Adelite AT-50) was added, and 60 g of water and 12 g of a film-forming aid (butyl acetate di-uxole) were further added, followed by stirring for 10 minutes to obtain a white paint.

Comparative Example 2 An acrylic emulsion (G-25, 50% by weight, manufactured by Mizutani Paint) was used instead of 200 g of the aqueous dispersion of Synthesis Example 1.
50 g and colloidal silica (Adelite AT-5)
0) A white paint was obtained using 150 g. That is, 50
In a 0 mL steel beaker, 10.8 g of distilled water, 5.0 g of thickener (6% by weight, UH-420), 4.0 g of dispersant
(Demol EP), 1.0 g of wetting agent (Emulgen L4
0), 0.8 g of an antifoaming agent (Nopco 8 manufactured by San Nopco Co., Ltd.)
034) and 80 g of titanium dioxide (JR-603) was gradually added while stirring at 1000 rpm with a disper. After the number of revolutions was set to 3000 rpm, stirring was continued for 15 minutes. Then, after the number of revolutions was set to 1000 rpm, 50 g of an emulsion (G-25, solid content 50% by weight, manufactured by Mizutani Paint) and 150 g of colloidal silica (Adelite AT-50) were further added. Further, 60 g of water and 12 g of a film-forming aid (butyl acetate di-euxole) were added and stirred for 10 minutes to obtain a white paint.

Comparative Examples 3 to 5 In the proportions shown in Table 3, coating compositions were obtained in the same manner as described above. Table 3
Shows the compositions of the paints of the above Examples and Comparative Examples.

Samples were prepared for the paints of the examples and comparative examples as follows. 15 parts by weight of water was added to 100 parts by weight of the paints obtained in Examples and Comparative Examples, and after adjusting the sample, 200 g of coating amount was applied to a 70 × 150 m slate plate.
/ M ² by a spray gun and left at room temperature for 7 days to form a coating film.

An L-shaped stainless steel test panel for stainability was prepared by applying a spray gun in the same manner as described above and leaving it to stand at room temperature for 7 days. The L-shaped stainless steel panel is a plate perpendicular to the ground (width 20c).
mx 30 cm in height) and an inclined plate (width 20 cm) extending obliquely upward from the upper end of this plate at an angle of 120 ^°.
× length 70 cm), and the end of the inclined plate was supportable.

Then, as described below, a coating film forming property,
Resistance, alkali resistance, boiling resistance, frost damage resistance, accelerated weather resistance,
When the outdoor exposure test and the stain resistance were evaluated, the results shown in Table 3 were obtained.

[Test Method and Evaluation Method] (1) Storage Stability 100 g of the paint was placed in a 200 ml container, stored in a hot-air drying oven at 50 ° C. for 10 days, and the state of the paint was visually observed. Evaluation was based on criteria.

◎: Not thickened at all ○: Slightly thickened が: Thickened but no problem in coating: Significantly thickened and unsuitable for coating × : In a gelled state (2) Gloss and coating film forming property The composition was applied on a glass plate with a doctor blade (4 mil), dried at room temperature, and the coating film was observed with a microscope and evaluated according to the following criteria. The gloss of the coating was measured as 60 ^° gloss.

◎: No cracking at a temperature of 5 ° C. or less ○: No cracking ▲: Slight cracking ×: Significant cracking (3) Adhesion Cross-cut 2 mm width A cellophane tape peeling test was carried out.
0, the case where all of the grids were peeled was displayed as 0/100.

(4) Water resistance The film was immersed in water for 20 days, and the state of the coating film was visually observed and evaluated according to the following criteria.

◎: There is no change in the coating film, and it is extremely good. ：: There is almost no change in the coating film, and good. Δ: The change in the coating film is small and there is no practical problem. ：: The change in the coating film is slightly large. A level at which a problem occurs in practical use. ×: The change in the coating film is large and the practicality is poor. Evaluation was made based on the same criteria.

(6) Frost resistance The test plate immersed in tap water was kept at -20 ° C for 16 hours for 20 hours.
The film was subjected to a 50-cycle freezing test in which the cycle was performed at 8 ° C. for 8 hours, and the state of the coating film was visually observed and evaluated based on the same criteria as in the above (4).

(7) Outdoor exposure test The appearance (gloss, crack, discoloration) of the coating film after 18 months was observed and evaluated according to the same criteria as in (4) above. The gloss retention of gloss was also evaluated.

(8) Contamination Six months after coating on the stainless steel plate shown in the figure, discoloration of the inclined portion and the vertical portion was visually observed, and evaluated based on the same criteria as in (4) above.

(9) Flame retardancy The paint was poured into a mold having a length of 150 mm, a width of 20 mm and a thickness of 10 mm, and was allowed to stand at room temperature for one month.
Test pieces of m ± 0.5 mm were prepared. This test piece was
A test was performed in accordance with IS K7201 and the flame retardancy was evaluated based on the burning oxygen index value according to the following criteria.

◎: 28 or more ○: 26 or more and less than 28 Δ: 24 or more and less than 26 ：: 20 or more and less than 24 ×: less than 20

[0115]

[Table 3]

[0116]

[Table 4]

As shown in Tables 3 and 4, Examples 1 to
In the paint No. 5, the stain resistance, the outdoor exposure test (weather resistance), the water resistance, etc. were improved by about 1 to 2 ranks as compared with Comparative Example 1. In addition, as is clear from the comparison between Example 2 and Comparative Example 2, in Example 2, the coating film forming properties, adhesion, and resistance were improved, and the coating film properties were well balanced. . Further, by using an emulsion containing colloidal silica, the gloss of the coating film can be adjusted in a wide range. Furthermore, in Examples 2 and 3 using emulsions having a high content of colloidal silica (Synthesis Examples 7 and 8), the flame retardancy was relatively evaluated based on the evaluation criteria. Flame retardancy can be imparted without adding.

Further, in the paint of Example 6 using Synthesis Example 10 (using titanium dioxide as fine particles), since titanium dioxide was covered with a polymer, the paint was used for comparison in light resistance, water resistance, alkali resistance and the like. It can be improved compared to Example 1 and has balanced physical properties. Further, Synthesis Example 10 (using titanium dioxide as fine particles)
And the paint of Example 7 using Synthesis Example 6 (using colloidal silica particles as fine particles), the contamination was further improved as compared with Example 6.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Tsutomu Mizutani 4-90 Nishi-Mikuni, Yodogawa-ku, Osaka-shi Mizutani Paint Co., Ltd. (72) Inventor Yoshiharu Kimura 1126-1 Takakaicho, Omihachiman City, Shiga Prefecture (72) Inventor Masatoshi Miyamoto 425-3 Ise-cho, Moriyama-shi, Shiga

Claims (14)

[Claims] Claims: 1. Direct or via a nonionic surfactant
An aqueous dispersion in which particles having a vinyl polymer bonded to the surface of inorganic or organic particles are dispersed in an aqueous medium. 2. The aqueous dispersion according to claim 1, wherein the inorganic or organic particles are colloidal silica or pigment. 3. The aqueous dispersion according to claim 1, wherein the nonionic surfactant is a polyoxyalkylene ether or a derivative thereof. 4. The cloud point of the nonionic surfactant is from 0 to 80.
The aqueous dispersion according to claim 1 or 3, wherein the aqueous dispersion is at 0 ° C. 5. The aqueous dispersion according to claim 1, wherein the nonionic surfactant has at least one ethylenically unsaturated group. 6. The vinyl polymer is at least one polymer selected from a (meth) acrylic monomer, an aromatic vinyl monomer, and a vinyl ester monomer.
An aqueous dispersion as described. 7. The aqueous dispersion according to claim 1, comprising 3 to 500 parts by weight of inorganic or organic particles and 0.1 to 20 parts by weight of a nonionic surfactant based on 100 parts by weight of the vinyl polymer. 8. The aqueous dispersion according to claim 1, wherein 80% by weight or more of the particles are spherical composite particles having a core-shell structure having inorganic or organic particles as a core and a vinyl polymer as a shell. 9. The aqueous dispersion according to claim 1, wherein the average particle diameter of the particles having the vinyl polymer bonded to the surface of the inorganic or organic particles is 10 μm or less. 10. An aqueous dispersion in which inorganic or organic particles are dispersed in an aqueous medium, and a vinyl monomer is polymerized in the presence of a nonionic surfactant at a temperature equal to or higher than the cloud point of the nonionic surfactant. Production method. 11. A vinyl monomer is polymerized by adsorbing a nonionic surfactant on the surface of inorganic or organic particles.
0. The method for producing an aqueous dispersion according to item 0. 12. The amount of the nonionic surfactant used is defined as (a-
1) less than the critical micelle concentration, and less than the saturated adsorption amount of inorganic or organic particles, (a-2) less than the critical micelle concentration, and more than the saturated adsorption amount of inorganic or organic particles, (b-1) critical micelle Concentration or more, and less than the saturated adsorption amount of inorganic or organic particles, or (b-2) or more than the critical micelle concentration, and more than the saturated adsorption amount of inorganic or organic particles, and the vinyl monomer is polymerized. 12. The method for producing an aqueous dispersion according to 10 or 11. 13. A coating composition comprising the aqueous dispersion according to claim 1. 14. The ratio of the composite particles having a core-shell structure to the inorganic or organic particles is expressed as solid / solid when the former / latter = 1
14. The coating composition according to claim 13, comprising an aqueous dispersion having a weight ratio of 00/0 to 50/50.