JP2003342526A - Self-cleaning aqueous coating composition and self- cleaning member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a self-cleaning aqueous coating composition which is directly applied to an organic adherend, is cured at a normal temperature to give a coating film body having weather-resistance performances and exhibiting antifouling performances by a photocatalyst. <P>SOLUTION: The self-cleaning aqueous coating composition comprises (a) a silicone resin precursor composed of an aqueous emulsion for forming a silicone resin coating film body and/or an aqueous emulsion for forming a fluororesin and/or colloidal silica, (b) photocatalytic particles or a photocatalytic sol and (c) water. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paint which is self-cleaning among paints applied to the wall surface of a building.

[0002]

2. Description of the Related Art In the fields of construction and paints, stains on exterior building materials, outdoor structures and coating films thereof have become a problem due to environmental pollution. Soot and particles floating in the atmosphere accumulate on the roof and outer walls of buildings in fine weather. The sediment is washed away by rainwater as it rains and flows down the outer wall of the building. Furthermore, in rainy weather, suspended dust is carried by rain and flows down on the outer wall of a building or the surface of an outdoor structure. As a result, contaminants adhere to the surface along the rainwater path. When the surface dries, striped stains appear on the surface. Dirt on building exterior materials and coatings consists of combustion products such as carbon black and inorganic pollutants such as urban dust and clay particles. It is considered that such diversity of pollutants complicates pollution control. (Yoshinori Tachibana, "Methods for Accelerating Contamination Testing of Exterior Wall Finishing Paints", Architectural Institute of Japan, Proceedings of Structural Studies, No. 404, October 1989, p.15-24)
It has been considered that a water-repellent paint such as polytetrafluoroethylene (PTFE) is preferable for preventing stains on the building exterior, but recently, for urban dust containing a large amount of hydrophobic components, , It is considered good to make the surface of the coating film as hydrophilic as possible (polymer, 44, 19
(May 1995, p.307) Therefore, it has been proposed to coat buildings with hydrophilic graft polymers (newspaper "Chemical Industry Daily"), January 30, 1995). According to reports, this coating film exhibits hydrophilicity with a contact angle with water of 30 to 40 °. However,
The contact angle of inorganic dust represented by clay minerals with water is 20 ° to 50 °, and it has affinity for the graft polymer with a contact angle with water of 30-40 ° and easily attaches to its surface. Therefore, it is considered that the coating film of this graft polymer cannot prevent stains due to inorganic dust. Further, conventionally, acrylic resin, acrylic silicone resin, aqueous silicone, block polymer of silicone resin and acrylic resin, acrylic styrene resin, sorbitan fatty acid ethylene oxide, sorbitan fatty acid ester, urethane acetate, polycarbonate diol and / or poly Various hydrophilic coatings composed of crosslinked urethane of isocyanate and crosslinked polyacrylic acid alkyl ester are commercially available. The contact angle of these hydrophilic paints with water is 50 to 70 ° at most, and it is not possible to effectively prevent the stains caused by urban dust containing a large amount of lipophilic components.

As a solution to the above problems, a coating composition containing a photocatalyst has been proposed. The surface of the photocatalyst-containing coating film can be made hydrophilic by ultraviolet rays of outdoor light, and the contact angle with water can be maintained at 20 ° or less. In addition, the oxidative decomposition of the photocatalyst suppresses the growth of molds and algae generated on the outer wall, and NO
It also has the effect of removing harmful substances such as x and SOx.

As a prior art for incorporating a photocatalyst into a coating composition, there are JP-A-11-1659 and JP-A-10-3169.
37 etc. can be mentioned. In JP-A-11-1659, a coating composition is obtained by dispersing a photocatalyst in a fluororesin and silica (or silica precursor) or silicone (or silicone precursor). In the examples, solvent-based fluorine resin and solvent-based silicon resin are used to obtain high durability. Although solvent-based paints have excellent weatherability, there is a risk that weather resistance will deteriorate after coating when applied to organic coatings that are easily affected by solvents such as emulsion paints. Occurrence of cracks is considered). Further, in the examples, the coating film is dried at 120 ° C., and it is considered that the curing condition after coating also affects the durability of the coating film in the art. Japanese Patent Laid-Open No. 10-316937
Then, a photocatalyst is dispersed in an aqueous silicone emulsion resin containing a surfactant to obtain a coating composition. In the description, it is possible to directly coat the organic coated plate. In the examples, the organic coated plate is directly coated and evaluated. But 2
The adhesiveness when a 0 μm thick film is applied cannot be said to be sufficient, and there is no disclosure of weather resistance performance data in this case. Thus, in a water-based coating composition containing a photocatalyst and exhibiting antifouling performance, a technique having sufficient adhesion to an organic coating material at room temperature coating and having weatherability has been disclosed so far. Absent.

[0005]

[Problems to be Solved by the Invention] Making the coating water-based is an indispensable issue in view of environmental load, consideration for the operator and surroundings of the construction area, and safety. A water-based coating composition containing a photocatalyst and exhibiting antifouling performance exhibits sufficient adhesion to an organic coating material at room temperature coating and has a weather resistance performance.

[0006]

In order to solve the above-mentioned problems, the self-cleaning aqueous coating composition according to the present invention has a contact angle with water reduced to, for example, 20 ° or less by light irradiation. Contains the following components (a), (b) and (c), and the blending amount of (b) in the total solid content of the coating is less than 5% by weight. (A) Silicone resin precursor comprising an aqueous emulsion capable of forming a silicone resin coating and / or an aqueous emulsion capable of forming a fluororesin and / or colloidal silica (b) photocatalyst particles or photocatalyst sol (c) water

The self-cleaning aqueous coating composition of the present invention preferably contains an inorganic coloring pigment.

The self-cleaning aqueous coating composition of the present invention preferably contains an inorganic extender pigment.

The extender pigment is preferably whiskers, mica or talc.

The solid content concentration of the self-cleaning aqueous coating composition is preferably 10% or more.

The film thickness of the coating film formed of the self-cleaning aqueous coating composition is preferably 5 μm or more.

The self-cleaning aqueous coating composition can be applied directly to an organic coating object and cured at room temperature.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a silicone resin precursor and / or an aqueous emulsion capable of forming a fluororesin, which is an aqueous emulsion capable of forming a silicone resin coating which is the component (a), and / or colloidal silica are It is a binder component that fixes photocatalyst particles and pigments. The total amount of the resin in the solid content is preferably 10 to 90% by weight. If it is less than 10%, the physical properties of the coating film such as adhesion with the article to be coated, coating film hardness, water resistance performance, and alkali resistance performance will deteriorate. When it is 90% or more, titanium oxide and the color pigment component are insufficient, and the desired function cannot be exhibited.

Specific silicone emulsions include methyltrimethoxysilane, methyltriethoxysilane, methyltrichlorosilane, methyltribromosilane, methyltriisopropoxysilane and methyltri-t-.
Butoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltrichlorosilane, ethyltribromosilane, ethyltriisopropoxysilane, ethyltrit-butoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n- Propyltrichlorosilane, n-propyltribromosilane, n-propyltriisopropoxysilane, n-propyltrit-butoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, n-hexyltrichlorosilane, n-hexyltrichlorosilane Bromsilane, n-hexyltriisopropoxysilane, n-hexyltri-t-butoxysilane, n-decyltrimethoxysilane, n-decyltriethoxysilane, n-decyltrichlorosilane, n- Syltribromosilane, n-decyltriisopropoxysilane, n-decyltrit-butoxysilane, n-octatrimethoxysilane, n-octatriethoxysilane, n-octatrichlorosilane, n-octatribromosilane, n-octa Triisopropoxysilane, n-octatrit-butoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltrichlorosilane, phenyltribromosilane, phenyltriisopropoxysilane, phenyltri-t-butoxysilane, vinyltrichlorosilane, vinyltrichlorosilane Bromsilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltri-t-butoxysilane, trifluoropropyltrichlorosilane, trifluoro B pills tri dibromostyrene silane, trifluoropropyl trimethoxy silane, trifluoropropyl triethoxy silane,
Vinyltrichlorosilane, trifluoropropyltriisopropoxysilane, trifluoropropyltrit-butoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltriisopropoxy Silane, γ-glycidoxypropyltri-t-butoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropyltriisopropoxysilane, γ-methacryloxy Propyltri-t-butoxysilane, γ-aminopropyltrimethoxysilane, γ
-Aminopropyltriethoxysilane, γ-aminopropyltriisopropoxysilane, γ-aminomethacryloxypropyltrit-butoxysilane, γ-methylcaptopropyltrimethoxysilane, γ-methylcaptopropyltriethoxysilane, γ-methyl Captopropyltriisopropoxysilane, γ-methylcaptopropyltri-t-butoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4
-Epoxycyclohexyl) ethyltriethoxysilane hydrolysis, dehydration polycondensation emulsion and the like can be preferably used.

Examples of the fluorine resin emulsion include polytetrafluoroethylene, polyvinylidene fluoride,
Polyvinyl fluoride, polychlorotrifluoroethylene,
Tetrafluoroethylene-hexafluoropropylene copolymer, ethylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, perfluorocyclopolymer, vinyl ether-fluoroolefin copolymer,
Vinyl ester-fluoroolefin copolymer, tetrafluoroethylene-vinyl ether copolymer, chlorotrifluoroethylene-vinyl ether copolymer,
An emulsion of a polymer having a fluoro group such as a tetrafluoroethylene urethane crosslinked product, a tetrafluoroethylene epoxy crosslinked product, a tetrafluoroethylene acrylic crosslinked product, and a tetrafluoroethylene melamine crosslinked product can be preferably used. The average particle size of the particles in the emulsion is preferably 50 to 300 nm.

It is preferable to add a solvent as a film-forming aid to assist the film-forming property of the emulsion. Examples of film-forming aids are alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, hexyl alcohol, octyl alcohol, and texanol, cellosolve, ethyl cellosolve, butyl cellosolve, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether propylene. Ethers such as glycol monomonoethyl ether, propylene glycol monoisobutyl ether, dipropylene glycol monobutyl ether, dipropylene glycol isobutyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monobutyl ether, tripropylene glycol monoisobutyl ether, butyl cellosolve acetate , Diethylene glycol mono Chill ether acetate dipropylene glycol isobutyl ether acetate, glycol ether esters, such as tripropylene glycol mono isobutyl ether acetate, etc. can be suitably used. The ratio of the film-forming aid added to the emulsion resin is 50.
Less than wt% is desirable. If it is added in an amount of 50% or more, a resin stringing phenomenon may occur.

The particle size of colloidal silica is not particularly limited, but is preferably 5 to 150 nm. A particulate shape is preferable, but a chain shape, a rod shape, a feather shape, a whisker shape, or the like can also be used. Water is suitable as the dispersion solvent for the colloidal silica, but an organic solvent can also be used.

The second other than the resin added as (a)
It is also possible to include an organic resin as the resin. The resin that can be added is at least one selected from the group consisting of alkyd resin, epoxy resin, acrylic resin, acrylic silicone resin, phenol resin, fluororesin, polyester resin, chlorinated rubber resin, urethane resin and melamine resin. It is an organic resin. The amount of the second resin added is preferably less than 100% by weight based on the total amount of the resin added as (a). The second resin is composed of an organic compound that is easily oxidatively decomposed by the photocatalyst, so if the amount added exceeds 100% by weight with respect to the total amount of the resin added as (a), the weather resistance of the coating film deteriorates.

The photocatalyst particles as the component (b) are not particularly limited as long as they have photocatalytic activity, and examples thereof include titanium oxide, zinc oxide, tin oxide and the like. Further, as a second component, V and F are provided inside and / or on the photocatalyst.
e, Co, Ni, Cu, Zn, Ru, Rh, Pd, A
The one carrying g, Pt and Au has a better photocatalytic activity, which is desirable. Among these, titanium oxide is preferable in terms of its photocatalytic activity, chemical stability, safety, availability, and cost. Note that it is preferable to use titanium oxide whose crystal type is anatase type because of its strong photocatalytic activity.

The photocatalyst particles can be used in the form of powder or sol. The proportion of photocatalyst particles in the solid content is preferably less than 5% by weight in order to avoid decomposition of the organic resin component in the coating film.

The primary particle size of titanium dioxide is 1 to 100 nm.
Are preferred. Those having a primary particle size of less than 1 nm are not preferable because the dispersion liquid of fine particles is not stable and secondary aggregation occurs and the photocatalytic activity becomes low when a coating film is formed. Further, those having a primary particle size of more than 100 nm are also not preferable because the photocatalytic activity when forming a coating film becomes low.

The inorganic extender pigments to be blended in the present invention include titanium oxide whiskers, calcium carbonate whiskers, potassium titanate whiskers, aluminum borate whiskers, mica, talc, barium sulfate, potassium carbonate, silica sand, diatomaceous earth, kaolin, clay, Ceramic earth, barium carbonate, etc. are suitable. Since these are inorganic components, they can impart high weather resistance to the coating film. In particular, the above whiskers, mica and talc are effective in preventing cracks during drying shrinkage and thermal shock. In order to obtain the crack prevention effect, the addition amount is preferably more than 5% by weight of the solid content, more preferably 10% by weight or more. Further, when it is more than 50% by weight, hardness and alkali resistance are deteriorated, so 50% by weight or less is preferable.

It is known that in whiskers, the aspect ratio (ratio of length: diameter) has an influence on crack prevention, and even in the examples described later, even if the addition amount of whiskers is slightly increased in mica (plate-shaped). Was occurring.
Therefore, it can be said that whiskers are more preferable when comparing mica and whiskers.

The color pigments added to the paint are roughly classified into inorganic pigments and organic pigments. Since an organic pigment is decomposed by a photocatalytic action to cause fading, an inorganic coloring pigment is preferred for addition to a photocatalyst-containing coating.

The inorganic coloring pigments include metal oxides such as titanium oxide white, titanium yellow, spinel green, zinc white, red iron oxide, chromium oxide, cobalt blue and iron black, and metals such as alumina white and yellow iron oxide. Hydroxides, ferrocyanide compounds such as navy blue, lead chromate such as yellow lead, zinc chromate and molybdenum red, sulfides such as zinc sulfide, vermilion, cadmium yellow and cadmium red, selenium compounds, barite, precipitation Sulfate such as barium sulfate, heavy calcium carbonate, carbonate such as precipitated calcium carbonate, hydrous silicate, clay, silicate such as ultramarine, carbon such as carbon black, aluminum powder, bronze powder, Metal powders such as zinc powder,
Examples include pearl pigments such as mica and titanium oxide.

As the solvent contained in the composition according to the present invention, (d) water is used.

In the coating composition of the present invention, the total solid content is preferably 10% by weight or more based on the total coating composition. By doing so, it becomes easier to make the coloring of the coating film uniform. In addition, it is difficult for the paint to drip when applied.

In the coating composition of the present invention, the above (a)
It is more preferable that the sum of the solid contents of the components, the components (b) and (c) exceeds 30% by weight with respect to the entire coating composition. As a result, a sufficient film thickness can be obtained by applying the roller coating only once or twice without particular overcoating, and the ultraviolet ray shielding effect can be obtained, and the weather resistance can be exhibited.

In the coating composition of the present invention, the above (a)
The sum of the solid contents of the component, the component (b) and the component (c) is preferably 60% by weight or less based on the whole coating composition. By so doing, the storage stability of the paint becomes sufficient.

The coating film thickness obtained by the coating composition of the present invention is preferably 5 μm or more, more preferably 20 μm or more. When the film thickness is 5 μm, the ultraviolet ray shielding rate becomes 95% or more. When it is 20 μm or more, the ultraviolet ray shielding rate becomes 99.9% or more. It is possible to prevent deterioration of the base due to ultraviolet rays, and prevent the photocatalyst layer from invading the article to be coated and the deterioration due to ultraviolet rays.

If desired, an anti-settling agent, a surfactant defoaming agent, a pH adjusting agent, a thickener, a curing agent, etc. may be added to the coating composition of the present invention.

The coating composition of the present invention can be directly applied to an organic object to be coated and dried at room temperature, and the obtained coated article has high durability and weather resistance. Here, the normal temperature refers to a normal temperature, and is generally 0 to 40 ° C. Although the coating method is not limited, roller coating, brush coating, spray coating, flow coating, dip coating, spin coating and the like are preferable. As a base material that can be used for coating the coating composition of the present invention, self-cleaning by rainfall can be expected, and in outdoor applications where there is no problem even if it is opaque, for example, metal, ceramics, plastic, wood, stone, cement , Concrete, combinations thereof, laminates thereof, coatings thereof, and the like. More specifically, exteriors of buildings such as outer walls and roofs; window frames; exteriors and coatings of vehicles such as railway cars, aircraft, ships, bicycles, motorcycles; signs, traffic signs, soundproof walls, insulators, shutters,
Street lights, pavements, outdoor lighting, stones and tiles for artificial waterfalls and fountains, bridges, outer wall materials, sealers between walls and glass, guardrails, balconies, vending machines, air conditioner outdoor units, outdoor benches, various display devices, shutters , Toll booths, toll boxes, roof gutters, coating of mechanical devices and articles, exterior and coating of advertising towers, structural members, and films and patches that can be attached to these articles.

[0033]

EXAMPLES Examples of self-cleaning aqueous coating compositions according to the present invention are shown. The constituent materials of the coating composition are shown below. 《Paint constituent materials》 ・ Potassium titanate whiskers: Otsuka Chemical Co., Ltd. Tismo D ・ Talc: Nippon Talc Co., Ltd. P3 ・ Aqueous inorganic coloring pigment paste: Titanium oxide white, Dainichiseika Kogyo MF5760 solids Concentration 65% ・ Photocatalyst particles: Titanium oxide powder STS-21 manufactured by Ishihara Sangyo Co., Ltd.
Average primary particle size 10 nm Solid content concentration 38.4% ・ Silicone resin: Silicone emulsion Trade name "BS45" (Manufacturing: Wacker Chemicals East Asia Co., Ltd., resin content 50%) ・ Fluoropolymer: Fluoropolymer emulsion Trade name "Lumiflon FE4300 (Manufacturing site: Asahi Glass Co., Ltd., resin content: 48%)"-Acrylic urethane resin: Acrylic urethane emulsion Product name "Boncoat CC5050" (Manufacturing site: Dainippon Ink Co., Ltd., resin content 45%)・ Colloidal silica: Product name “ST-” manufactured by Nissan Chemical Industries, Ltd.
50 "Average primary particle size 20 to 30 nm Solid content concentration 4
9% -Solvent: Water-Film forming aid: Texanol Trade name "CS-12" (Manufacturing: Chisso Co., Ltd.) The above components were mixed at the ratios shown in the examples and thoroughly stirred before use.

Example 1 29.4 parts by weight of inorganic pigment paste, 13.1 parts by weight of potassium titanate whisker powder and 4.6 parts by weight of titanium oxide sol were added to 39.4 parts by weight of water. This mixture was kneaded using glass beads to prepare a pigment base. To 10.1 parts by weight of this pigment base, 19.9 parts by weight of a silicon emulsion liquid and a film forming aid were added, and the mixture was stirred for 5 minutes with a stirring blade to obtain a coating composition # 1.

(Example 2) 25.2 parts by weight of inorganic pigment paste, 15.0 parts by weight of potassium titanate whisker powder and 0.5 parts by weight of titanium oxide sol were added to 45.2 parts by weight of water. This mixture was kneaded using glass beads to prepare a pigment base. 15.9 parts by weight of a fluorine emulsion and 2.7 parts by weight of a film-forming auxiliary were added to 84.1 parts by weight of this pigment base, and the mixture was stirred for 5 minutes by a stirring blade to obtain a coating composition # 2.

Example 3 Inorganic pigment paste 24.7 parts by weight, talc 8.2 parts by weight, potassium titanate whisker powder 7.8 parts by weight, titanium oxide sol 5.7 parts by weight and water 97.2 parts by weight. Was added. This mixture was kneaded using glass beads to prepare a pigment base. To 143.6 parts by weight of this pigment base, 1 part of silicone emulsion liquid
4.7 parts by weight, 15.3 parts by weight of fluorine emulsion liquid,
Coating composition # 3 was obtained by adding 3.3 parts by weight of a film-forming aid and further adding water to make the solid content concentration 40% by weight, and then stirring with a stirring blade for 5 minutes.

Example 4 Inorganic pigment paste 19.6 parts by weight, potassium titanate whisker powder 8.4 parts by weight,
25.3 parts by weight of water was added to 4.4 parts by weight of the titanium oxide sol. This mixture was kneaded with glass beads to prepare a pigment base. With respect to 57.7 parts by weight of this pigment base, 15.8 parts by weight of colloidal silica, 13.5 parts by weight of silicon emulsion liquid, and 13.3 parts of fluorine emulsion liquid.
2 parts by weight and 3.5 parts by weight of a film-forming aid were added, and water was further added to adjust the solid content concentration to 40% by weight, followed by stirring with a stirring blade for 5 minutes to obtain coating composition # 4.

(Example 5) Inorganic pigment paste 29.4 parts by weight, potassium titanate whisker powder 7.8 parts by weight,
Water (23.3 parts by weight) was added to titanium oxide sol (5.2 parts by weight). This mixture was kneaded with glass beads to prepare a pigment base. With respect to 65.7 parts by weight of this pigment base, 15.6 parts by weight of colloidal silica, 18.7 parts by weight of a silicon emulsion solution and 3.1 parts by weight of a film-forming aid were added, and water was further added to obtain a solid content concentration. Was adjusted to 40% by weight and then stirred with a stirring blade for 5 minutes to obtain a coating composition # 5.

Example 6 32.5 parts by weight of inorganic pigment paste, 7.6 parts by weight of potassium titanate whisker powder,
22.7 parts by weight of water was added to 0.58 parts by weight of titanium oxide sol. This mixture was kneaded with glass beads to prepare a pigment base. To 63.4 parts by weight of this pigment base, 27.8 parts by weight of colloidal silica, 8.9 parts by weight of a silicone emulsion and 1.0 part by weight of a film-forming aid were added, and water was added to obtain a solid content concentration. Was adjusted to 40% by weight and then stirred with a stirring blade for 5 minutes to obtain coating composition # 6.

Example 7 Inorganic pigment paste 18.4 parts by weight, talc 5.2 parts by weight, potassium titanate whisker powder 2.6 parts by weight, titanium oxide sol 1.4 parts by weight, and water 10 parts by weight were added. . This mixture was kneaded using glass beads to prepare a pigment base. This pigment base 3
To 7.6 parts by weight, 31.2 parts by weight of colloidal silica, 33.5 parts by weight of a fluorine emulsion solution and 3.7 parts by weight of a film-forming aid were added, and further water was added to obtain a solid content concentration of 40 parts by weight. %, And then stirred with a stirring blade for 5 minutes to obtain coating composition # 7.

(Example 8) Inorganic pigment paste 25.4 parts by weight, potassium titanate whisker powder 7.6 parts by weight,
Water (22.8 parts by weight) was added to titanium oxide sol (5.1 parts by weight). This mixture was kneaded with glass beads to prepare a pigment base. To 60.9 parts by weight of this pigment base, 15.3 parts by weight of colloidal silica, 14.0 parts by weight of silicon emulsion solution, 9.7 parts by weight of acrylic urethane emulsion solution, and 4.2 parts by weight of film-forming aid were added. Further, water was further added to adjust the solid content concentration to 40% by weight, and then the mixture was stirred for 5 minutes with a stirring blade to obtain a coating composition # 8.

(Example 9) 2.6 parts by weight of titanium oxide sol, 82 parts by weight of colloidal silica, 15.4 parts by weight of silicon emulsion solution and 2.6 parts by weight of film-forming aid were mixed,
Further, water was added to adjust the solid content concentration to 40% by weight and then stirred for 5 minutes with a stirring blade to obtain a coating composition # 9.

Comparative Example 1 79.3 parts by weight of water was added to 36.6 parts by weight of the inorganic pigment paste and 13.9 parts by weight of titanium oxide sol. This mixture was kneaded with glass beads to prepare a pigment base. To this pigment base (129.3 parts by weight) was added 49.6 parts by weight of a fluorine emulsion solution and 8.2 parts by weight of a film-forming aid, and water was further added to adjust the solid content concentration to 40% by weight, followed by stirring. The coating composition # 10 was obtained by stirring with a blade for 5 minutes.

(Comparative Example 2) 75.8 parts by weight of water was added to 35.8 parts by weight of the inorganic pigment paste and 6.1 parts by weight of titanium oxide sol. This mixture was kneaded with glass beads to prepare a pigment base. After adding 58.1 parts by weight of an acrylic urethane emulsion liquid and 9.2 parts by weight of a film-forming aid to 119.7 parts by weight of this pigment base, water was further added to make the solid content concentration 40% by weight. Stirring was carried out for 5 minutes with a stirring blade to obtain coating composition # 11.

The composition of solids of the coating composition for Nos. 1 to 11 is shown in Table 1. The same applies to all of the coating compositions # 1 to 11 (San Nopco's "SN Deformer 3").
97 ") was added to the coating composition in an amount of 0.3% by weight.

[0046]

[Table 1]

1. Coating film performance evaluation <Test sample coating method> Acrylic organic sealer (product name "EM Sealer" made by Suzuka Fine) is spray-coated on a slate plate cut into 150 mm x 65 mm,
It was dried at room temperature for 16 hours. The thickness of the acrylic sealer layer was 40 to 50 μm. Subsequently, the coating compositions shown in Examples and Comparative Examples were directly spray-coated to obtain coatings. This film thickness was 40 to 50 μm. The evaluation was performed after performing a predetermined curing at room temperature. If necessary, heat drying was performed.

(Presence or absence of cracks after coating) After coating, it was dried at room temperature for 1 day. For the evaluation of the presence or absence of cracks, the presence or absence of cracks was confirmed visually and by observing the surface of the test piece with an optical microscope. As a microscope, Keyence VK-850
The observation was performed at a magnification of 200 using 0. The one in which cracks can be visually confirmed was marked with X, the one in which cracks could be confirmed with a microscope was marked with Δ, and the one without cracks was marked in ○. (Initial adhesion) After coating, it was dried at room temperature for 14 days. An X-cut tape method test was conducted according to JIS K5400 8.5 Adhesion Test Method. The sample with no peeling was rated as O, the sample with partial peeling as Δ, and the sample with complete peeling as x. Further, a test for evaluating the adhesiveness to the organic coating plate and the acrylic plate was separately conducted. The test paint was applied to the test base material by spray painting. The film thickness was adjusted to 20 μm. The test piece was dried at room temperature for 14 days and then JI
A cross-cut test was conducted in accordance with SK5400 8.5. The organic coating board is a slate board coated with an epoxy clear sealer paint and dried at room temperature for 1 day, and a fluorine paint (Asahi Glass Coat And Resin Co., Ltd.) is used as a top coating film.
"Bonflon"), urethane paint (Suzuka Fine
"Wide urethane"), acrylic silicone paint (Isam paint "Neosilica"), acrylic emulsion paint (Suzuka Fine "AEP Modern") were applied at room temperature. (Weather resistance test) After coating, the test piece dried at room temperature for 2 weeks was subjected to an accelerated weather resistance test for 600 hours. The accelerated weather resistance was evaluated based on the sunshine carbon arc equation test of JIS K5400 9.8 accelerated weather resistance test. After the test, the degree of cracking and choking was examined.
The crack confirmation method was the same as above. For choking, the degree of coating film detachment was examined with a finger (○: no detachment, Δ: surface a little detached, ×: significant detachment, × × peeling at the interface of the undercoat paint). (Alkali resistance) A test was performed based on JIS K5400 8.21 Alkali resistance test. The test procedure is as follows: A beaker with a capacity of 300 ml is filled with about 90 mm of 5% aqueous solution of sodium carbonate at 20 ± 2 ° C
Up to the height of the test piece, and the test piece is immersed in this aqueous solution in a substantially vertical direction, and after 24 hours, the test piece is taken out, the surface of the test piece is gently rinsed with water, and the water adhering thereto is wiped off lightly. After standing in the test chamber for 3 hours, the degree of haze and discoloration should be compared with the part not soaked in the test solution, compared to the part not cracked, swollen and softened and eluted on the surface and not soaked. Quality standard: There was no cracking, swelling, peeling or softening and elution, and there was no noticeable clouding or discoloration compared to the part not soaked, which was marked as ◯. A cellophane adhesive tape is attached to a sample that has been subjected to an alkali test and dried at room temperature for 3 hours or more after washing, and the tape is completely adhered to the coating film by rubbing the tape with an eraser. 1-2 after attaching the tape
After a minute, hold one end of the tape and keep it perpendicular to the coated surface,
Peel it off momentarily. When the magnitude of the resistance when the tape was peeled off was not changed from that before the test, it was evaluated as ○, when the resistance was slightly reduced, it was evaluated as Δ, and when there was almost no resistance, it was evaluated as ×. (Evaluation of hydrophilicity) After coating drying, 180 ° C /
The test piece dried for 20 minutes was irradiated with ultraviolet rays of 5 mW / cm ^{2 with} a germicidal lamp, the change in contact angle with water was measured, and the number of days until it became 20 ° or less was evaluated. After coating, immediately place the test piece outdoors without heating and drying (south facing /
The same evaluation was performed. CX-150 manufactured by Kyowa Interface Science Co., Ltd. was used for the contact angle measurement, and the measurement was performed 3 to 5 seconds after dropping a water droplet from a microsyringe.

Table 2 shows the evaluation results regarding cracks after coating, initial adhesion, weather resistance, alkali resistance and hydrophilicity in Examples and Comparative Examples. Table 3 shows the adhesion test results of the organic paint-coated plate, the acrylic plate, and the paint of the example.

[0050]

[Table 2]

[0051]

[Table 3]

As described above, in a coating composition exhibiting self-cleaning properties by a photocatalyst, an aqueous emulsion capable of forming a silicone resin precursor and / or a fluorine resin, which is an aqueous emulsion in which a binder component can form a silicone resin coating film. And / or colloidal silica, and by setting the content of the photocatalyst in the coating film solid content to less than 5% by weight, a coating having sufficient adhesion and excellent durability even when applied to an organic coating object. It has become possible to obtain members. Further, the durability performance is further improved by adding an inorganic coloring pigment and an inorganic extender pigment. It was also confirmed that the same effect can be obtained by adding an organic resin of a different type from the above as a binder.

EFFECTS OF THE INVENTION According to the present invention, in a coating composition exhibiting self-cleaning property by containing photocatalyst particles or sol, a silicone resin precursor comprising a binder component and an aqueous emulsion capable of forming a silicone resin film, and / or
Alternatively, an aqueous emulsion and / or colloidal silica capable of forming a fluororesin is used, and the content of the photocatalyst in the solid content of the coating film is less than 5% by weight so that sufficient adhesion can be obtained even when applied to an organic coating object. Therefore, it is possible to obtain a covering member having excellent durability. Further, the durability performance is further improved by adding an inorganic coloring pigment and an inorganic extender pigment.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C09D 5/16 C09D 5/16 127/12 127/12 201/00 201/00 C09K 3/00 C09K 3 / 00 R 112 112 (72) Norio Sendoda Norio 28, Toranomon, Minato-ku, Tokyo Within Japan Hiderotate Coatings Co., Ltd. (72) Tatsuhiko Kuga 1-28 Toranomon, Minato-ku, Tokyo Japan Hiderotatec Coatings Co., Ltd. F-term (reference) 4D075 BB24Z BB92Z CA34 CA37 DA06 DB01 DB12 DB14 DB21 DB31 DC03 DC08 DC13 DC15 DC38 EA06 EA23 EB16 EB42 EB56 EC02 EC04 EC11 EC22 4J038 CD091 DL03 HA216 HA446 HA536 HA546 KA08 MA08 MA10 NA05 NA05

Claims (12)

[Claims] 1. The following components (a), (b) and (c) are included:
A self-cleaning aqueous coating composition, wherein the solid content of component (b) is less than 5% by weight of the total solid content of the coating. (A) Silicone resin precursor comprising an aqueous emulsion capable of forming a silicone resin coating and / or aqueous emulsion capable of forming a fluororesin and / or colloidal silica (b) photocatalyst particles or photocatalyst sol (c) water 2. The self-cleaning aqueous coating composition according to claim 1, further comprising an inorganic coloring pigment. 3. The self-cleaning aqueous coating composition according to claim 1 or 2, further comprising an inorganic extender pigment. 4. The inorganic extender pigment is titanium whisker,
The self-cleaning aqueous coating composition according to claim 3, which is a potassium titanate whisker, mica, or talc. 5. The self-cleaning aqueous paint composition according to claim 1, further comprising an organic resin as a resin other than the component (a). 6. The self-cleaning aqueous coating composition according to claim 1, wherein the coating composition has a solid content concentration of 10% by weight.
A self-cleaning aqueous coating composition characterized by the above. 7. The self-cleaning aqueous coating composition according to any one of claims 1 to 6, which is used for direct application to an organic coating object. 8. The self-cleaning aqueous coating composition according to any one of claims 1 to 7, which is coated on a place where sunlight is irradiated and where it can be rained, dried at room temperature, and then exposed for 6 months. A self-cleaning coating composition having a contact angle with water of 20 ° or less 9. The self-cleaning aqueous coating composition according to any one of claims 1 to 8, wherein the coating film is formed at room temperature. 10. A self-cleaning member obtained by applying the self-cleaning aqueous coating composition according to claim 1 to a substrate. 11. A self-cleaning member, wherein the dry film thickness of the self-cleaning aqueous coating composition formed in the self-cleaning member according to claim 10 is 5 μm or more. 12. The self-cleaning member according to claim 10 or 11, wherein the base material to be coated is a base material having an organic coating film.