Self-cleaning water-based coating compositions, and self-cleaning member

ES 2 425 840 T3

DESCRIPTION

Self-cleaning water-based coating compositions and self-cleaning members

Technical field

This invention relates to a coating that is applied to the exterior surface of a building and exhibits self-cleaning properties.

Background of the technique

In recent years, photocatalytic materials have gained considerable attention as materials that become hydrophilic upon exposure to sunlight and perform a self-cleaning function with the help of rain when applied to the exterior surface of a building. They have also gained attention as environmentally friendly materials that break down toxic gases such as NOx.

For example, Japanese Patent Open to Public Inspection No. 10-195333 describes that a coating film capable of decomposing NOx is formed by applying a coating containing water-soluble silicate, a curing agent, and photocatalytic powder (titanium dioxide or zinc oxide) to the surface of a tunnel wall. or a railing and heat treating it.

Japanese Patent Open to Public Inspection No. 10-237354 discloses that a building material superior in self-cleaning properties is obtained by applying a coating containing lithium silicate and titanium dioxide to a building material and heat treating it.

In recent years, there has been an increasing trend to use a water-based coating rather than a solvent-based coating from the standpoint of work environment, effect on surroundings, and odor. As a result, water-based photocatalytic coating materials to be applied to building exteriors etc. as described above have also been proposed.

For example, Japanese Patent Open to Public Inspection No. 10-195369 describes a coating composition that is obtained by mixing a photocatalyst and a perfluorocopolymer in the emulsion state.

Japanese Patent Open to Public Inspection No. 10-279886 proposes a coating composition that is a silicone emulsion containing a photocatalyst and a fluoro group.

In addition, in the fields of building construction and coating, dirt and stains on the exterior of the building, exterior structures and the coating film thereon have been raised with problems with increasing environmental pollution. Airborne dust and particulate matter accumulate on the roofs and exterior walls of buildings in good weather. The accumulations are washed away by the rain when it rains and slides down the exterior walls of buildings. In addition, soot and dust from the air are carried by rainwater in rainy weather and slide down the exterior walls of buildings and the surface of external structures. As a result, pollutants bind to the surface of exterior walls and those of structures along the path that rainwater has taken. Once the surfaces dry, streaked dirt appears on the surfaces.

Dirt and stains on the external faces of the building or building covering films are made of contaminants from: combustion products such as carbon black, urban soot and dust, and inorganic matter such as clay particles. This diversity of pollutants makes pollution preventive measures complicated (Kitsutaka, Y. "Accelerated Test Method for Contamination of Exterior Wall Coating", Trasactions of Structural Division, Architectural Institute of Japan, no. 404, Oct. 1989, 15-24).

Previously, it was generally accepted an idea that water repellent coatings such as polytetrafluoroethylene (PTFE) were preferably used to prevent dirt and stains on the exteriors of buildings, etc., as described above. In recent years, however, an idea has been generally accepted that the surface of coating films on building exteriors, etc., should be as hydrophilic as possible so as to avoid soot fouling. urban and dust, which contains many hydrophobic components (Macromolecule, Vol. 44, May, 1995, 307). In such circumstances, an intention has been made that the exteriors of buildings should be coated with a hydrophilic grafted polymer (Newspaper, "Japan Chemical Week", January 30, 1995). According to the newspaper report, the hydrophilic graft polymer coating film shows a hydrophilic nature such that the contact angle of water on the coating film is 30 to 40 °. However, the contact angle between the inorganic powder, typified by a clay mineral, and water is 20 ° to 50 °, and said inorganic powder has an affinity for the grafted polymer in that the contact angle of water is 30 to 40 ° and is likely to bond to the surface of the grafted polymer. Thus, the coating film of said grafted polymer is not able to prevent dirt and stains from inorganic dust. Meanwhile, a variety of hydrophilic coatings have been sold which are composed of acrylic resin, acrylic resin-silicone, water-based silicone, silicone resin block copolymer and acrylic resin, acrylic resin-styrene, ethylene acid oxide sorbitan fatty acid, sorbitan fatty acid ester,

ES 2 425 840 T3 urethane-based acetate, cross-linked polycarbonate diol urethane and / or polyisocyanate or polyacrylic alkylester. The contact angle between each of the above hydrophilic coatings and water is 50 to 70 ° at most, and such coatings are not able to effectively prevent dirt and stains from urban soot and dust, which contain many lipophilic components.

As means of solving the problems described above, coating compositions containing a photocatalyst have been proposed. Photocatalyst-containing coating films are able to make their surface hydrophilic when exposed to UV rays from outside light and keep the contact angle of water in them 20 ° or less. Furthermore, they have the effect of both inhibiting the spread of mold and algae and of eliminating toxic substances such as NOx and SOx.

Examples of coating compositions containing a photocatalyst are those described in: 1. WO 98/03607, 2. Japanese Patent Laid-Open No. 11-1659, 3. Japanese Patent Open to Public Inspection No. 2002-69376, 4. Japanese Patent Open to Public Inspection No. 10-316937 and 5. WO 99/51345.

WO 98/03607 describes a composition that includes: photocatalytic particles composed of metal oxide; at least one selected from the group consisting of silica fine particles, a silicone resin film precursor capable of forming a silicone resin film, and a silica film precursor capable of forming a silica film; and a solvent, wherein the concentration of the total amount of the above photocatalytic particles plus the above fine silica particles or the precursor, in terms of silica weight, in the composition is 0.01 to 5% by weight. In the examples described in the above specification, tetrafunctional silane was used as the silicone resin film precursor capable of forming a silicone resin film. The specification states that to prevent the film from becoming opaque white due to uneven light reflection and to allow it to be essentially transparent, the thickness of the film is preferably 0.4 µm or less. Furthermore, in the examples described in the specification, the alcohol having high power to dissolve organic resins, such as methanol or propanol, was used together with water so that the tetrafunctional silane dissolves.

Japanese Patent Open to Public Inspection No. 11-1659 describes a coating composition that is obtained by dispersing a photocatalyst in fluorine resin and silica (or the precursor thereof) or silicone (or the precursor thereof). In the examples described in the specification, the solvent-based fluorine resin and the solvent-based silicon resin were used so that a highly durable coating is produced. Solvent-based coatings are superior in weathering performance; however, when applied to an organic base that is susceptible to attack by solvents, such as emulsion paint, their weatherability may possibly deteriorate (problems such as peeling and breakage may possibly occur) after application. In the examples described in the specification, the cover film was dried at 120 ° C, so the curing conditions after coating can further affect the durability of the cover film in this technique.

Japanese Patent Open to Public Inspection No. 2002-69376 describes a self-cleaning coating composition that is obtained by mixing photocatalytic particles or the sol thereof in trifunctional silicone resin and / or trifunctional silicone resin precursor capable of forming a silicone resin film and a whisker. (or mica, talc) and providing a film such that the contact angle of water on its surface is decreased to 20 ° or less when exposed to light.

Japanese Patent Open to Public Inspection No. 10-316937 describes a coating composition that is obtained by dispersing photocatalytic particles in water-based silicon emulsion resin containing a surfactant such that the photocatalytic particles constitute 5% by weight or more of the composition. The specification states that the composition can be applied directly to dishes whose surface has an organic paint coating. And in the examples described in the report, the direct application of the composition in said dishes is carried out and evaluated.

The water-based coatings described in Japanese Patent Laid-Open Nos. 10195333 and 10-237354 have poor wettability to base materials that have hydrophobic substances on their surface, such as plastics and painted steel, and therefore their applications are limited to glass, wood, and metals.

The water-based coatings described in Japanese Patent Laid-Open Nos. 10195369 and 10-279886 have improved wettability to base materials that have hydrophobic substances on their surface, such as plastics and painted steel; however, assuming they are used outdoors, the contact angle of the water on them immediately after application is still too great. As a result, they could not perform their self-cleaning function with the help of rain immediately after application.

From the standpoints of environmental impact, in consideration of the safety and security of the builders or a construction site and its vicinity, replacing solvent-based coatings with water-based ones is the issue to look at.

ES 2 425 840 T3

Self-cleaning coatings for use on exterior walls are required to have good weatherability. To improve the weatherability of a coating, particularly of a coating containing a photocatalyst, the thickness of the coating film has to be increased to an extent such that the radicals generated from the photocatalyst by exposure of the coating film to UV rays do not reach the underlying layer of the coating film (several pm or more) and thus protect the underlying layer from the activity of the photocatalyst. Although on the other hand, with increasing thickness of the coating film, breaks on the surface of the film are more likely to occur. Thus, how to make weatherability and shatter prevention compatible is a problem with self-cleaning coatings containing a photocatalyst.

In refinishing existing walls, organic primer coats are often used. These primer coats are composed of acrylic emulsion and are therefore susceptible to attack by strong solvents. Accordingly, when it is intended to apply a coating directly on such organic bases, a water-based coating is desirably used.

As mentioned above, WO 98/03607 describes a coating composition in which tetrafunctional silane is used primarily as a silicone resin film precursor. However, when a film containing tetrafunctional silane is formed to a thickness of several pm so as to impart weatherability to the film, tears are likely to occur in the film.

Furthermore, when the above coating composition is applied directly on an organic base, the alcoholic solvent attacks the organic base due to its high dissolving power against the resin, which can cause breakage or peeling of the film immediately after application. of the coating composition.

The inventors of this invention proposed in Japanese Patent Laid-Open No. 2002-69376 a photocatalytic coating composition that includes a mixture of: a trifunctional silicone resin and / or a trifunctional silicone resin precursor capable of forming a silicone resin film; and whisker so as to provide a self-cleaning coating composition that has both weatherability and difficulty in causing breakage, although they could not render the composition a water-based one. Furthermore, the coating composition described in Japanese Patent Laid-Open No. 2002-69376 was so tough that it needed a proper internal coating when applied to an organic material to be coated.

In the examples described in Japanese Patent Laid-Open No. 10-316937, the 1 and 20 pm coating films were formed on the respective plate whose surface has an organic paint coating, and the adhesion etc. of each coating film was evaluated. The evaluation showed that the adhesion was not sufficient for the 20 µm thick coating film applied directly on the plate whose surface has an organic paint coating. The report did not describe any data on the film's weather resistance.

No prior art has disclosed a water-based coating composition containing photocatalyst and showing stain protection performance that provides a coating film that not only has good adhesion to organic materials such as objects to be coated even when coating is carried out. at ordinary temperature, but also have good weather resistance performance.

As described above, there has been no water-based photocatalytic coating composition that has good adhesion to a substrate, does not cause breakage when used outdoors, and has good weatherability performance, even when formed into a film. which is thick enough to intercept ultraviolet light.

This invention has been made in light of the circumstances described above. Accordingly, an object of this invention is to provide: a photocatalytic coating material that does not pose problems in terms of work environment, effect on the surroundings and odor, that can be applied on base materials that have hydrophobic substances on their surface, such as plastics and painted steel, and that allows, when form into a film on base materials that have hydrophobic substances on their surface, that the formed film has firm adhesion to the base materials, that allows the contact angle of the water on the surface of the film to be smaller even immediately after the application of the composition, and therefore the film to perform its self-cleaning function with the help of rain immediately after use, and furthermore that it allows the above-described state of the film to be maintained for a long time by exposing the film to sunlight; a photocatalytic composite material formed by applying the above photocatalytic coating material to a base material having a hydrophobic substance on its surface; and a method to produce the same.

Another object of this invention is to provide a photocatalyst-containing water-based coating composition showing stain protection performance that provides a coating film that not only has good adhesion to organic materials such as objects to be coated even when its

ES 2 425 840 T3 coating is carried out at ordinary temperature, but also has good weathering performance and therefore does not cause breakage when used outdoors.

Description of the invention

To solve the problems described above, this invention aims to provide a self-cleaning member obtainable by coating a base material having an organic paint film on its surface with a self-cleaning water-based coating composition that provides a film of coating so that the contact angle of the water on the surface of the coating film is lowered to 20 ° or less with the help of light irradiation; specifically, the composition includes the following ingredients (a), (b) and (c):

(a) a silicone resin precursor composed of a water-based emulsion capable of forming a silicone resin film and / or a water-based emulsion capable of forming a fluorine resin and / or colloidal silica, (b) particles photocatalytic or photocatalytic sol, and (c) water, wherein ingredient (b) constitutes less than 5% by weight of the total solid matter of the coating composition.

Preferably the self-cleaning water-based coating composition of this invention contains an inorganic coloring pigment.

Preferably the self-cleaning waterborne coating composition of this invention contains an inorganic expander pigment.

Preferably the above inorganic expander pigment is whiskey, mica or talc.

Preferably the solid content in the above self-cleaning waterborne coating composition is 10% or more.

Preferably the coating film formed from the above self-cleaning waterborne coating composition is 5 µm or more thick.

The above self-cleaning water-based coating composition can be directly coated on an organic base and hardened at ordinary temperature.

Best mode to carry out the invention

The self-cleaning water-based coating composition according to a preferred embodiment of this invention provides a coating film such that the contact angle of water on the surface of the coating film is decreased to 20 ° or less with the aid of light irradiation; specifically, the coating composition includes the following ingredients (a), (b), and (c):

(a) a silicone resin precursor composed of a water-based emulsion capable of forming a silicone resin film and / or a water-based emulsion capable of forming a fluorine resin and / or colloidal silica, (b) particles photocatalytic or photocatalytic sol, and (c) water, wherein ingredient (b) constitutes less than 5% by weight of the total solid matter of the coating composition.

In this invention, ingredient (a), that is, a silicone resin precursor composed of a water-based emulsion capable of forming a silicone resin film and / or a water-based emulsion capable of forming a fluorine resin and / or colloidal silica, is a binder component of the coating that helps to fix the photocatalytic particles and pigments. Preferably, the total content of said resins in the total solid matter of the coating composition is 10 to 90% by weight. If the content is less than 10%, the physical properties of the coating film, such as adhesion to organic bases, film hardness, water resistance and alkali resistance, deteriorate, while if the content is 90% or more, the components such as titanium oxide and coloring pigment are insufficient, which inhibits the coating film from exerting the desired function.

Specific examples of suitable silicone emulsions used are hydrolysis emulsions or dehydration condensation polymers of, for example, methyltrimethoxysilane, methyltriethoxysilane, methyltrichlorosilane, methyltribromosilane, methyltriisopropoxysilane, methyltri-t-butoxysilane, ethyltrimethoxysilane, ethyltrimethoxysilane, ethyltrimethoxysilane, ethyltrimethoxysilane,

ES 2 425 840 T3 ethyltrichlorosilane, ethyltribromosilane, ethyltriisopropoxysilane, ethyltri-t-butoxysilane, n-propyltrimethoxysilane, npropyltriethoxysilane, n-propyltrichlorosilane, n-propyltribromosilane, n-propyltriimethoxysilane, n-propyltriimethoxysilane-hexylanotrioxysilane, n-propyltriimethoxysilane-hexylatrioxysilane , n-hexyltrichlorosilane, n-hexyltribromosilane, n-hexyltriisopropoxysilane, nhexyltri-t-butoxysilane, n-decyltrimethoxysilane, n-decyltriethoxysilane, n-decyltrichlorosilane, n-decyltribromosilane, ndecyltriisopropoxysilane, n-decyltri-t-butoxysilane, n-octatrimethoxysilane, n-octatriethoxysilane, n-octatrichlorosilane, noctatribromosilane, n-octatriisopropoxysilane, n-octatri-t-butoxysilane, phenyltrimethoxysilane, phenyltrimethoxysilano-triylanoxysilane, phenyltrimethoxysilanoxysilane, phenyltrimethoxysilanoxysilane, phenyltrimethoxysilanoxysilane, butoxysilane, vinyltrichlorosilane, vinyltribromosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltri-t-butoxysilane, trifluoropropyltrichlorosilane, trifluoropropiltritidibromosilano, trifluoropropyltrimethoxysilane, trifluoropropiltrietoxisilano, vinyltrichlorosilane, trifluoropropiltriisopropoxisilano, t-butoxysilane trifluoropropiltri-, γ-glycidoxypropyltrimethoxysilane, γglicidoxipropiltrietoxisilano, γ-glycidoxypropyltriisopropoxysilane, γ-t-butoxysilane glicidoxipropiltri-, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-metacriloxipropiltriisopropoxisilano, γ-methacryloxypropyltri t- butoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ aminopropyl, γ-t-butoxysilane aminometacriloxipropiltri-, γ-metilcaptopropiltrimetoxisilano, metilcaptopropiltrietoxisilano γ, γ-metilcaptopropiltriisopropoxisilano, γ-t-butoxysilane metilcaptopropiltri-, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane and e- (3,4-epoxycyclohexyl) ethyltriethoxysilane.

Examples of suitably used fluorine resin emulsions are polymer emulsions having a fluoro group, such as polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, polychlorotrifluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, ethylene-tetrafluoroethylene copolymer. , ethylenechlorotrifluoroethylene copolymer, tetrafluoroethylene-perfluoroalkylvinylether copolymer, perfluorocyclo polymer, vinyl ether-fluroolefin copolymer, vinyl ester-fluoroolefin copolymer, tetrafluoroethylene-vinyl ether copolymer, chlorotrifluoroethylene-vinyl ether copolymer, tetrafluoroethylene urethane cross-linked polymer, tetrafluoroethylene epoxy cross-linked polymer, tetrafluoroethylene acryl cross-linked polymer, and methylene tetrafluoroethylene cross-linked polymer. Preferably, the average particle size of the particles in the emulsion is 50 to 300 nm.

To aid the film integrity of the emulsion, it is preferable to add a solvent as a film integrity aid. Concrete examples of properly used film integrity assistants are: alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, hexyl alcohol, octyl alcohol, and texanol; Ethers such as cellosolve, ethyl cellosolve, butyl cellosolve, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monoethyl ether, propylene glycol monoisobutyl ether, dipropylene glycol monobutyl ether, dipropylene glycol isobutyl ether, tripropylene glycol monobutyl ether, tripropylene glycol monobutyl ether, tripropylene glycol monobutyl ether, tripropylene glycol monoethyl ether; glycol ether esters such as butyl cellosolve acetate, diethylene glycol monoethyl ether acetate, dipropylene glycol isobutyl ether acetate and tripropylene glycol monisobutyl ether acetate. Preferably, the amount of the film integrity aid added to the emulsion resin is less than 50% by weight. If the amount is 50% or more, resin entanglement or the like may occur.

With respect to colloidal silica, its particle size is preferably (not limited to) 5 to 150 nm. Colloidal silica in the form of a particle is preferably used; however, chain-type, rod-type, feather-type or whisker-type colloidal silica can also be used. As a dispersion medium for colloidal silica, water is preferable, although organic solvents can also be used.

The self-cleaning water-based coating composition may include an organic resin, such as a second resin, in addition to the resins added as ingredient (a). The resin that can be added as a second resin is at least one type of organic resin selected from the group consisting of alkyd resin, epoxy resin, acrylic resin, acrylic-silicone resin, phenolic resin, fluorine resin, polyester resin, resin resin. chlorinated rubber, urethane resin and melamine resin. Preferably, the amount of the second resin added is less than 100% by weight of the total amount of the resins added as ingredient (a). If the amount is more than 100% by weight of the total amount of the added resins as ingredient (a), the weather resistance of the coating film deteriorates, because the second resins are composed of organic compounds susceptible to decomposition. by oxidation by photocatalyst.

Examples of photocatalytic particles used as ingredient (b) include: titanium oxide, zinc oxide and tin oxide particles, but are not limited to these, as long as they have photocatalytic activity. Photocatalytic particles with V, Fe, Co, Ni, Cu, Zn, Ru, Pd, Ag, Pt or Au, as a second component, carried within themselves and / or on their surface are preferable, because they have enhanced photocatalytic activity. .

Of the above photocatalytic particles, those of titanium oxide are preferably used for their photocatalytic activity, chemical stability, safety, availability and low cost. The anatase type of titanium oxide is particularly preferably used for its strong photocatalytic activity.

The photocatalytic particles can be used in the form of powder or sol. To avoid decomposition of the organic resin ingredient in the coating film, the photocatalytic particles constitute less than 5% by weight of the total solid matter of the coating composition.

The primary particle size of titanium dioxide is preferably 1 to 100 nm. Primary particles smaller than 1 nm in size are not preferable because the dispersion of such fine particles is not stable and their

Secondary agglomeration is likely to occur, which would cause deterioration of photocatalytic activity when a coating film is formed. At the same time, primary particles larger than 100 nm in size are not preferable, either, because they can also cause deterioration of photocatalytic activity when forming a coating film.

Examples of inorganic expander pigments suitably used in this invention include: titanium oxide whisker, calcium carbonate whisker, potassium titanate whisker, aluminum borate whisker, mica, talc, barium sulfate, potassium carbonate, sand silica, diatomaceous earth, kaolin, clay, potter's clay, and barium carbonate. Because the pigments described above are inorganic ingredients, they can provide a coating film to form with excellent weatherability. The use of the whiskers described above, mica or talc, is particularly effective in preventing breakage when the coating film undergoes dry shrinkage or thermal shock. To obtain a breakage-preventing effect, preferably the amount of these added inorganic expander pigments is more than 5% by weight of the total solid matter of the coating composition and preferably 10% by weight or more. Furthermore, the amount is preferably 50% by weight or less. The reason is that if the amount is more than 50% by weight, the hardness and alkali resistance of the coating film to be formed deteriorates.

In whiskers, their aspect ratio (length: diameter ratio) is known to have an effect in preventing breakage, and the examples described later confirmed that the breaks occurred somewhat in mica (in the form of a sheet), but not in whiskers, even when they were added in the same amount. Therefore, of mica and whiskers, whiskers are preferable.

Coloring pigments added to coatings are classified into two broad types: inorganic and organic. However, when used in photocatalyst-containing coatings, inorganic coloring pigments are preferable because organic pigments decompose by photocatalytic action and discolor.

Examples of 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 black iron oxide; metal hydroxides such as alumina white and yellow oxide; ferrocyanides such as Prussian blue; lead chromates such as chromium yellow, zinc chromate, and molybdate red; sulfides such as zinc sulfide, vermilion, cadmium yellow, and cadmium red; selenides; sulfates such as barium salts and precipitated barium sulfate; carbonates such as ground calcium carbonate and precipitated calcium carbonate; silicates such as silicate hydrate, clay and ultramarine; carbons such as carbon black; metallic powders such as aluminum powder, bronze powder, and zinc powder; and pearl pigments such as titanate mica.

As the solvent contained in the composition of this invention, (d) water is used.

In the coating composition of this invention, preferably the sum of the solid matter constitutes 10% by weight or more of the entire coating composition. This makes it easy to pigment the coating film to form uniformly. In addition, sagging of the coating at the time of application of the coating is difficult to occur.

In the coating composition of this invention, more preferably the sum of the solid matter in ingredients (a), (b) and (c) constitutes more than 30% by weight of the entire coating composition.

This makes it possible to obtain a sufficient film thickness only by roller coating once or twice without overlapping the coating composition one on the other and a coating film that produces a UV shielding effect and exerts good weather resistance. .

In the coating composition of this invention, preferably the sum of the solid matter in ingredients (a), (b) and (c) constitutes 60% by weight or less of the entire coating composition.

This provides sufficient stability.

Preferably, the thickness of the coating film obtained using the coating composition of this invention is 5 µm thick or more and preferably 20 µm or more. With the 5 pm thick film, the UV shielding efficiency is 95% or more. With the film 20 pm or more thick, the UV shielding efficiency is 99.9% or more. This makes it possible to prevent the substrate from deteriorating due to UV rays and furthermore to prevent the base from being attacked by the photocatalytic layer or from deteriorating due to UV rays.

Additives such as anti-settling agent, surfactant, anti-foaming agent, pH adjuster, thickening agent, and hardener can be added to the coating composition of this invention, depending on the situation.

The coating composition of this invention can be applied directly on an organic base and dried at ordinary temperature, and the resulting coated article has excellent durability and weatherability. "Ordinary temperature" used in this document means normal temperature, generally 0 to 40 ° C. Examples

Suitable coating methods used are, not limited to, roll coating, brush coating, spray coating, flow coating, dip coating and spin coating.

When it is intended to use the coating composition of this invention outdoors, where the self-cleaning action of the coating with the help of rain can be expected and the opacity of the coating film is not a problem, the base materials to which it is Applicable coating composition are, for example, metals, ceramics, plastics, wood, stone, cement, concrete, the combination thereof, the laminates thereof, and things coated with that. More specifically, applications for the coating composition of this invention include: for example, the exterior of buildings such as exterior walls and roofs; external face and covering of means of transport such as window frames, rolling stock, airplanes, boats, bicycles, motorcycles; advertising panel covering, traffic signs, noise insulation walls, insulation, rain shutter doors, street lamps, paving, outdoor lighting, artificial waterfalls, artificial fountain stones / tiles, bridges, exterior wall materials, sealants between walls o glass, railings, porches, vending machines, outdoor units of air conditioners, outdoor benches, various types of screens, blinds, toll barriers, ticket machines, gutters, equipment or articles; exterior face and covering of advertising supports; structural members; and films or emblems that can be attached to the items described above.

In the following examples of self-cleaning water-based coating compositions according to this invention will be described.

First, the materials constituting coating compositions according to this invention will be shown.

Coating Materials • Potassium titanate whisker: Tismo N, by Otsuka Chemical Co., Ltd.

• Talc: P3, by Nippon Talc Co., Ltd.

• Water-based paste of inorganic color pigment: Titanium Oxide White, MF5760, by Dainichiseika Color and Chemical Mfg. Co., Ltd., with a solid content of 65%.

• Photocatalytic Particles: Titanium Oxide Powder, STS-21, ISHIHARA SANGYO Co., Ltd. with an average primer layer particle size of 10 nm and a solids content of 38.4%.

• Silicone resin: silicone emulsion, BS45, by Wacker Chemicals East Asia, with a resin content of 50%.

• Fluorine resin: Fluorine resin emulsion, Lumiflon FE4300, by Asahi Glass Co., Ltd., with a resin content of 48%.

• Acrylic urethane resin: Acrylic urethane emulsion, Boncoat CC5050, by Dainippon Ink and Chemicals, Incorporated, with a resin content of 45%.

• Colloidal Silica: ST-50, by Nissan Chemicals Industries, Ltd., with an average primer layer particle size of 20 to 30 nm and a solid content of 49%.

• Solvent: water.

• Film Integrity Wizard: texanol, CS-12, by CHISSO CORPORATION.

The materials shown above were mixed in ratios shown in the examples and stirred thoroughly so as to be used as coating compositions.

Example 1

39.4 parts by weight of water were added to a mixture of 23.0 parts by weight of inorganic pigment paste, 13.1 parts by weight of potassium titanate whisker powder and 4.6 parts by weight of sol of titanium oxide. The mixture was kneaded using glass beads to prepare a pigment base. 19.9 parts by weight of liquid silicone emulsion and film integrity assistant were added to 80.1 parts by weight of pigment base and stirred with a stirrer for 5 minutes to produce coating composition no. 1.

Example 2

45.2 parts by weight of water were added to a mixture of 23.4 parts by weight of inorganic pigment paste, 15.0 parts by weight of potassium titanate whisker powder and 0.5 parts by weight of sol of titanium oxide. The mixture was kneaded using glass beads to prepare a pigment base. 15.9 parts by weight were added

ES 2 425 840 T3 of fluorine liquid emulsion and 2.7 parts by weight of film integrity assistant to 84.1 parts by weight of pigment base and stirred with a stirring element for 5 minutes to produce a coating composition no. 2.

Example 3

97.2 parts by weight of water were added to a mixture of 24.7 parts by weight of inorganic pigment paste,

8.2 parts by weight of talc, 7.8 parts by weight of potassium titanate whisker powder and 5.7 parts by weight of titanium oxide sol. The mixture was kneaded using glass beads to prepare a pigment base. 14.7 parts by weight of liquid silicone emulsion, 15.3 parts by weight of liquid fluorine resin emulsion, and 3.3 parts by weight of film integrity assistant were added to 143.6 parts by weight basis of pigment and water was added further so that the solid content in the mixture was 40% by weight. The resulting mixture was stirred with a stirrer for 5 minutes to produce coating composition no. 3.

Example 4

25.3 parts by weight of water were added to a mixture of 19.6 parts by weight of inorganic pigment paste, 8.4 parts by weight of potassium titanate triquete powder and 4.4 parts by weight of sol of titanium oxide. The mixture was kneaded using glass beads to prepare a pigment base. 15.8 parts by weight of colloidal silica, 13.5 parts by weight of liquid silicone emulsion, 13.2 parts by weight of liquid fluorine resin emulsion and 3.5 parts by weight of film integrity assistant were added. to 57.7 parts by weight of pigment basis and additional water was added so that the solid content in the mixture was 40% by weight. The resulting mixture was stirred with a stirrer for 5 minutes to produce coating composition no. Four.

Example 5

23.3 parts by weight of water were added to a mixture of 29.4 parts by weight of inorganic pigment paste, 7.8 parts by weight of potassium titanate triquete powder and 5.2 parts by weight of sol of titanium oxide. The mixture was kneaded using glass beads to prepare a pigment base. 15.6 parts by weight of colloidal silica, 18.7 parts by weight of liquid silicone emulsion and 3.1 parts by weight of film integrity aid were added to 65.7 parts by weight of pigment base and added additional water so that the solid content in the mixture was 40% by weight. The resulting mixture was stirred with a stirrer for 5 minutes to produce coating composition no. 5.

Example 6

22.7 parts by weight of water were added to a mixture of 32.5 parts by weight of inorganic pigment paste, 7.6 parts by weight of potassium titanate triquete powder and 0.58 parts by weight of sol of titanium oxide. The mixture was kneaded using glass beads to prepare a pigment base. 27.8 parts by weight of colloidal silica, 8.9 parts by weight of liquid silicone emulsion and 1.0 part by weight of film integrity aid were added to 63.4 parts by weight of pigment base and added additional water so that the solid content in the mixture was 40% by weight. The resulting mixture was stirred with a stirring element for 5 minutes to produce a coating composition no. 6.

Example 7

10 parts by weight of water were added to a mixture of 18.4 parts by weight of inorganic pigment paste, 5.2 parts by weight of talc, 2.6 parts by weight of potassium titanate whisker powder and 1, 4 parts by weight of titanium oxide sol. The mixture was kneaded using glass beads to prepare a pigment base. They were added

31.2 parts by weight of colloidal silica, 33.5 parts by weight of fluorine resin liquid emulsion and 3.7 parts by weight of film integrity assistant at 37.6 parts by weight of pigment base and additional water was added so that the solid content in the mixture was 40% by weight. The resulting mixture was stirred with a stirrer for 5 minutes to produce coating composition no. 7.

Example 8

22.8 parts by weight of water were added to a mixture of 25.4 parts by weight of inorganic pigment paste, 7.6 parts by weight of potassium titanate whiskey powder and 5.1 parts by weight of sol of titanium oxide. The mixture was kneaded using glass beads to prepare a pigment base. 15.3 parts by weight of colloidal silica, 14.0 parts by weight of liquid silicone emulsion, 9.7 parts by weight of liquid acrylic urethane resin emulsion, and 4.2 parts by weight of silicone integrity assistant were added. film at 60.9 parts by weight of pigment basis and additional water was added so that the solid content in the mixture was 40% by weight. The resulting mixture was stirred with a stirrer for 5 minutes to produce coating composition no. 8.

Example 9

ES 2 425 840 T3

2.6 parts by weight of titanium oxide sol, 82 parts by weight of colloidal silica, 15.4 parts by weight of liquid silicone emulsion and 2.6 parts by weight of film integrity assistant were mixed, and added water to the mixture so that the solid content in the mixture was 40% by weight. The resulting mixture was stirred with a stirrer for 5 minutes to produce coating composition no. 9.

Comparative Example 1

79.3 parts by weight of water was added to a mixture of 36.6 parts by weight of inorganic pigment paste and 13.9 parts by weight of titanium oxide sol. The mixture was kneaded using glass beads to prepare a pigment base. 49.6 parts by weight of fluorine resin liquid emulsion and 8.2 parts by weight of film integrity assistant were added to 129.3 parts by weight of pigment base and additional water was added so that the content in solid in the mixture was 40% by weight. The resulting mixture was stirred with a stirrer for 5 minutes to produce coating composition no. 10.

Comparative Example 2

77.8 parts by weight of water were added to a mixture of 35.8 parts by weight of inorganic pigment paste and 6.1 parts by weight of titanium oxide sol. The mixture was kneaded using glass beads to prepare a pigment base. 58.1 parts by weight of acrylic urethane liquid emulsion and 9.2 parts by weight of film integrity assistant were added to 119.7 parts by weight of pigment base and water was added so that the solid content in the mixture was 40% by weight. The resulting mixture was stirred with a stirrer for 5 minutes to produce coating composition no. eleven.

The composition of the solid matter is shown in Table 1 for each of the coating compositions no. 1 to no. 11. 0.3% by weight of antifoam agent (defoamer SN 397, by San Nopco Limited) was added to each of coating compositions no. 1 to no. eleven.

Table 1

Composition and concentration of solid matter in each of the coating compositions of examples and comparative examples.

(% in weigh)

<td></td><td>Silicone emulsion</td><td>Colloidal silica</td><td>Fluorine resin emulsion</td><td>Photocatalytic Titanium Oxide</td><td>Pigment (white)</td><td>Potassium Titanate Whiskey</td><td>talcum powder</td><td>Acrylic urethane emulsion</td><td>Solid content (%)</td>

<td>Example 1</td><td> 25</td><td></td><td></td><td> 4,5</td><td> 37,5</td><td> 33</td><td></td><td></td><td> 39,8</td>

<td>Example 2</td><td></td><td></td><td> 20</td><td> 0,5</td><td> 40</td><td> 39,5</td><td></td><td></td><td> 38,1</td>

<td>Example 3</td><td> 15</td><td></td><td> 15</td><td> 4,5</td><td> 32,7</td><td> 16</td><td> 16,8</td><td></td><td> 40,0</td>

<td>Example 4</td><td> 15</td><td> 15</td><td> 15</td><td> 4,5</td><td> 30</td><td> 20,5</td><td></td><td></td><td> 40,0</td>

<td>Example 5</td><td> 21</td><td> 14</td><td></td><td> 4,5</td><td> 43</td><td> 17,5</td><td></td><td></td><td> 40,0</td>

<td>Example 6</td><td> 10</td><td> 25</td><td></td><td> 0,5</td><td> 47,5</td><td> 17,0</td><td></td><td></td><td> 40,0</td>

<td>Example 7</td><td></td><td> 30</td><td> 31</td><td> 1,0</td><td> 23</td><td> 5</td><td> 10</td><td></td><td> 40,0</td>

<td>Example 8</td><td> 16</td><td> 14</td><td></td><td> 4,5</td><td> 38</td><td> 17,5</td><td></td><td> 10</td><td> 40,0</td>

<td>Example 9</td><td> 15,5</td><td> 80</td><td></td><td> 4,5</td><td></td><td></td><td></td><td></td><td> 40,0</td>

<td>Comparative Example 1</td><td></td><td></td><td> 45</td><td> 10</td><td> 45</td><td></td><td></td><td></td><td> 40,0</td>

<td>Comparative Example 2</td><td></td><td></td><td></td><td> 10</td><td> 45</td><td></td><td></td><td> 45</td><td> 40,0</td>

1. Coating film performance evaluation.

Specimen coating method.

Acrylic organic sealer (EM Sealer, by Suzukafine Co., Ltd) was spray coated on tiles that had been cut to 150mm x 65mm and dried at room temperature for 16 hours. The thickness of the acrylic sealant film was 40 to 50 pm. Then, the coating compositions shown in the examples and the examples

Comparative ES 2 425 840 T3 were directly spray coated onto the respective sealer coated tiles to produce coated tiles. The thickness of each coating film was 40 to 50 pm. The evaluation of the coating films was carried out after subjecting the coated tiles to the prescribed cure. Heat drying was carried out depending on the situation.

(Presence or absence of breaks)

After application of the respective coating compositions, the coated tiles were dried at room temperature one day. The presence or absence of breaks was verified by observing the surface of each specimen visually and with an optical microscope. The optical microscope used was VK-8500, by KEYENCE Corporation and the observation was carried out at 200 magnification. Films in which tears were observed visually were judged as P, those in which tears were observed under the microscope as F, and those in which no tears were observed as G.

(Initial adhesion)

After application of the respective coating compositions, the coated tiles were dried at room temperature for 14 days. The X-cut adhesion test was carried out for each coated tile according to JIS K5400 8.5. Films that did not peel at all were judged as G, those that partially peeled off as F, and those that were completely peeled off as P.

The evaluation of adhesion to an organic painted plate and an acrylic plate was also carried out, separately. The test coating compositions were spray coated on the respective test base materials. The thickness of the coating films was adjusted to 20 pm. The specimens were dried at room temperature for 14 days and then cross cut adhesion test according to JIS K5400 8.5. The used organic painted plates were prepared by applying a clear epoxy sealer coating on the tiles, drying the sealer coated tiles at ordinary temperature for one day, and applying a fluorine coating (Bonflon, by Asahi Glass Coat &amp; Resin, Co., Ltd). .), a urethane coating (Wideurethane, by Suzakafine Co., Ltd.), an acrylic-silicone coating (Neosilica, by Isamu Paint Co., Ltd.), or an acrylic emulsion coating (AEP Modern, by Suzukafine Co., Ltd.), as an exterior coating, on the respective tiles coated with ordinary temperature sealer.

(Weathering test)

The accelerated weathering test was carried out for specimens that had dried at room temperature for 2 weeks after being coated with the respective coating compositions. The evaluation was carried out based on the accelerated weathering test using solar carbon arc according to the JIS K5400 9.8 standard. After the test, the degree of breakage and friction wear was evaluated. The presence or absence of breaks was confirmed in the same way as before, while that of friction wear by evaluating the degree of flaking with the fingers (films without flaking confirmed with this were judged as G, those with little flaking as F, those with remarkable flaking as P, and those with peeling that occurs at the interface with the primer layer as VP).

(Alkaline resistance)

The alkaline resistance test was carried out according to JIS K5400 8.21. The procedure for the test was as follows: pour 5% aqueous sodium carbonate solution at 20 ± 2 ° C into a 300 ml beaker at a height of approximately 90 mm; immerse each specimen in the aqueous solution while it remains vertically; remove the specimen from the beaker after 24 hours of immersion and subsequently wash its surface while gently pouring water; dry the bound water slightly from the specimen and allow the specimen to stand in the test room for 3 hours; and evaluating the presence of breakage, swelling and softening elution of the surface of the specimen and comparing the degree of turbidity and change in color caused in the submerged part of the specimen with the non-submerged part.

Quality standard: Films were judged as G when their surface had no breakage, swelling, peeling and softening elution after dipping in alkali and haze and color change in its part dipped in alkali is not serious, even when it is compared to that part not immersed in alkali.

Specimens that have undergone the alkali resistance test were washed and dried at room temperature for 3 hours. Then, adhesive cellophane tape was put on each specimen and erased with an eraser so that the tape completely stuck to its cover film. One to two minutes after the tape was glued to the overlay film, one end of the tape was grasped and held perpendicular to the surface of the overlay film and the tape was peeled off the overlay film in one example . When the films have tear strength as great as that of the films before the alkali resistance test, they were judged as G. When they have slightly less tear strength than the films before alkali resistance test, they were judged as F. And when they have low tear strength, they were judged as P.

ES 2 425 840 T3 (Evaluation of hydrophilic nature)

Specimens that have been heat dried at 180 ° C for 20 minutes after their coating films dried were exposed to 5 mW / cm UV light.² from a germicidal lamp so that the change in the contact angle of water in its coating films was measured, and its hydrophilic nature was evaluated by the number of days it took to decrease the contact angle to 20 ° or less. At the same time, for specimens that have not been heat-dried, although they were placed outside (with their coating surface facing south and inclined at 45 °) immediately after application of the coating composition, their Hydrophilic nature was also evaluated in the same way as above. The contact angle was measured with CX-150 by Kyowa Interface Science Co., Ltd., after a lapse of 3 to 5 seconds after a drop of water was dripped through the micro-syringe.

The evaluations of breakage after coating, initial adhesion, weatherability, alkali resistance and hydrophilic nature for the coating compositions of the examples and the comparative examples are shown in Table 2. The adhesion of the coating compositions of the Examples to organic painted plates and an acrylic plate were tested as well. The results are shown in Table 3.

Table 2

Evaluations for Cover Films of the Examples and Comparative Examples (1)

<td rowspan="2"></td><td rowspan="2">Breakage after coating</td><td rowspan="2">Tape adhesion after coating</td><td colspan="2">Weather resistance</td><td colspan="2">Alkali resistance</td><td colspan="2">Hydrophilic nature</td>

<td>Break</td><td>Scaled</td><td>Appearance</td><td>Tape test</td><td>Germicidal lamp</td><td>Outdoor exposure</td>

<td>Example 1</td><td>G</td><td>G</td><td>G</td><td>G</td><td>G</td><td>G</td><td>5 days</td><td>155 days</td>

<td>Example 2</td><td>G</td><td>G</td><td>G</td><td>G</td><td>G</td><td>G</td><td>4 days</td><td>123 days</td>

<td>Example 3</td><td>G</td><td>G</td><td>G</td><td>G</td><td>G</td><td>G</td><td>4 days</td><td>90 days</td>

<td>Example 4</td><td>G</td><td>G</td><td>G</td><td>G</td><td>G</td><td>G</td><td>1 day</td><td>45 days</td>

<td>Example 5</td><td>G</td><td>G</td><td>G</td><td>G</td><td>G</td><td>G</td><td>1 day</td><td>20 days</td>

<td>Example 6</td><td>G</td><td>G</td><td>G</td><td>G</td><td>G</td><td>G</td><td>4 days</td><td>65 days</td>

<td>Example 7</td><td>G</td><td>G</td><td>G</td><td>G</td><td>G</td><td>G</td><td>2 days</td><td>65 days</td>

<td>Example 8</td><td>G</td><td>G</td><td>G</td><td>G</td><td>G</td><td>G</td><td>2 days</td><td>65 days</td>

<td>Example 9</td><td>G</td><td>G</td><td>G</td><td>F</td><td>G</td><td>G</td><td>5 days</td><td>155 days</td>

<td>Comparative Example 1</td><td>G</td><td>G</td><td>F</td><td>P</td><td>G</td><td>G</td><td>1 day</td><td>45 days</td>

<td>Comparative Example 2</td><td>G</td><td>G</td><td>P</td><td>VP</td><td>G</td><td>G</td><td>1 day</td><td>45 days</td>

Table 3

Cross cut adhesion test on organic painted plates and acrylic plate (2)

<td rowspan="2"></td><td colspan="4">Exterior coating on organic painted dishes</td><td rowspan="2">Acrylic plate</td>

<td>Fluorine coating</td><td>Urethane coating</td><td>Acrylic-silicone coating</td><td>Acrylic coating</td>

<td>Example 4</td><td> 100/100</td><td> 100/100</td><td> 100/100</td><td> 100/100</td><td> 100/100</td>

<td>Example 7</td><td> 100/100</td><td> 100/100</td><td> 100/100</td><td> 100/100</td><td> 100/100</td>

ES 2 425 840 T3

As described above, in coating compositions that develop self-cleaning properties in the presence of a photocatalyst, when the binder components are a silicone resin precursor composed of a water-based emulsion capable of forming a silicone resin film and / or a water-based emulsion capable of forming a fluorine and / or colloidal silica resin and the content In 5-photocatalyst the solid matter of the coating film to be formed is less than 5% by weight, a coating member can be obtained which has good adhesion even to organic bases and excellent durability. If an inorganic coloring pigment and an inorganic expander pigment are added to the coating compositions, the durability of the resulting coating member is further improved. The evaluations confirmed that when an organic resin is added as a binder different from those described above, the same effects can be obtained.