Water-repellent substrate

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention, cement moldings, stone tiles, building materials of the metal tiles such as civil engineering and construction materials such as concrete, sandstone, etc. stone construction materials Monument, glasses, glass products such as optical lenses, synthetic resin plate, a plastic sheet, The present invention relates to a water-repellent substrate having a stain-proof and dew-proof function in which the surface of a substrate such as a synthetic resin product such as a fiber is subjected to a water-repellent treatment and the surface has a water-repellent action and a photocatalytic action.

【0002】

[Conventional technology]

Conventionally, the following are known as water-repellent substrates having a water-repellent effect. For example, Japanese Patent Application Laid-Open No. 7-291667 states that it is transparent, has water repellency, absorbs and shields ultraviolet rays and infrared rays, and can sufficiently block ultraviolet rays having a wavelength around 400 nm, without impairing optical characteristics. In order to obtain water-repellent ultraviolet-infrared absorbing glass having excellent durability such as adhesion, chemical resistance, and scratch resistance, a silicon isocyanate compound and a fluoroalkylsilane compound are contained on one side of a transparent base material such as a glass substrate. An ultraviolet ray formed by forming a water-repellent thin film, applying a synthetic resin-based primer coating solution prepared by dissolving and adding a fluorescent whitening agent, an ultraviolet absorber and an infrared absorber to the other surface of the substrate, and heat-curing the film. -Repellent provided with an infrared-absorbing thin film and a protective thin film formed by applying a silicone-based hard coating solution in which a siloxane prepolymer is dissolved in an organic solvent on the ultraviolet / infrared-absorbing thin film and heat-curing to form a coating. Aqueous UV / infrared absorbing glass is described.

【0003】

Japanese Patent Application Laid-Open No. 8-143332 describes strong water repellency that can prevent the surface of a substrate to be treated such as an optical element with an antireflection film from being contaminated for a long period of time and can always secure a good surface. In order to form a thin film, the surface of the base material is activated by an ion beam method, a plasma method, a bombard method, or the like before the formation of the water-repellent thin film, and the activated surface is water-repellent by the PVD method. A method for forming a thin film of an organic silicon compound containing a certain perfluoro group is disclosed.

【0004】

Japanese Patent Application Laid-Open No. 8-12922 states that tetraalkoxysilane or a multimer thereof is hydrolyzed in order to prevent the generation of streak-like stains that are likely to occur in the part where rainwater collects and flows, such as under the window frame of a building. It is described that a surface treatment agent containing 0.01 to 50% of a silane compound having a decomposed silanol group is used, and the surface of a hydrophobic synthetic resin coating film of an outdoor article is treated with this surface treatment agent to form a thin film. ..

【0005】

Further, conventionally, a water-repellent member having both a water-repellent function and a photocatalytic function on the surface thereof is also known. For example, in Japanese Patent Application Laid-Open No. 9-228073, in a water-repellent member having a water-repellent coating film formed on its surface, a layer containing photocatalytic particles and an electron-capturing metal is formed as a base layer of the water-repellent coating film. The water-repellent member is described.

【0006】

On the other hand, amorphous titanium peroxide sol and amorphous titanium oxide sol having no photocatalytic ability, and titanium oxide sol obtained by heating these sol at 100 ° C. or higher are also known. For example, Japanese Patent Application Laid-Open No. 9-71418 describes a titania film formed from an amorphous titanium peroxide sol, and Japanese Patent Application Laid-Open No. 9-262481 by the present inventors supports and fixes a photocatalyst on a substrate. A method for producing a photocatalyst, which is a method for producing a photocatalyst using a titanium oxide sol having a photocatalytic ability and an amorphous titanium peroxide sol having no photocatalytic ability, is described in JP-A-10-53437 as a substrate. Methods for fixing the amorphous titanium peroxide layer are described respectively.

【0007】

[Problems to be Solved by the Invention]

As described above, a water-repellent member having both a water-repellent function and a photocatalytic function on its surface is known, but in the water-repellent member described in JP-A-9-228073, the surface thereof is used as a water-repellent layer and a base layer. Since the photocatalyst functional layer containing the photocatalytic particles and the electron trapping metal is provided, it cannot be said that the photocatalytic function is sufficient. In addition, in the case of a porous and water-absorbent base material such as concrete or rock, deterioration of the base material and deterioration of cosmetic properties due to aging such as stains such as oil and algae generation on the surface due to infiltration of rainwater etc. There was a problem such as occurring.

【0008】

An object of the present invention is that the surface thereof has both an excellent water-repellent function and an excellent photocatalytic function, and not only has both an antifouling effect and a dew-proof effect, but also the water-repellent coating film is made of an organic polymer resin. It is also an object of the present invention to provide a surface water-repellent substrate that is not deteriorated by the photocatalytic layer.

【0009】

[Means for solving problems]

In order to solve the above problems, we conducted intensive research and found that a specific photocatalyst, that is, an amorphous titanium peroxide sol having no photocatalytic ability, was heated at 100 ° C or higher on the surface of the water-repellent base material. To complete the present invention, it has been found that a water-repellent substrate provided with a photocatalytic layer using an anatase-type titanium oxide sol having photocatalytic activity obtained by the above has not only excellent photocatalytic performance but also excellent water-repellent performance. I arrived.

【0010】

Further, a coating layer using an alkali metal silica compound and / or an amorphous titanium peroxide sol or an amorphous titanium oxide sol on the surface of a base material on which a water-repellent coating film that is deteriorated by a photocatalyst made of an organic polymer resin or the like is formed. A water-repellent substrate provided with a photocatalytic layer using an anatase-type titanium oxide sol obtained by heating an amorphous titanium peroxide sol at 100 ° C or higher on the water-repellent substrate has only excellent photocatalytic ability. We have found that the water-repellent coating film made of an organic polymer resin is not deteriorated by the photocatalytic coating layer and can maintain excellent water-repellent performance for a long period of time, and have completed the present invention.

【0011】

That is, in the present invention, the water repellency of an alkali metal silica compound or a coating film using an amorphous titanium peroxide sol, an amorphous titanium oxide sol or an amorphous titanium hydroxide containing the alkali metal silica compound on the surface of the base material is provided. A coating film is formed, and a photocatalyst layer using an anatase-type titanium oxide sol obtained by heating an amorphous-type titanium peroxide sol at 100 ° C. or higher is provided on the water-repellent coating film. Regarding a water-repellent substrate.

【0012】

Further, in the present invention, a water-repellent coating film is formed on the surface of the base material, and a coating layer using an amorphous titanium peroxide sol or an amorphous titanium oxide sol is provided on the water-repellent coating film, and the coating layer is provided. The present invention relates to a water-repellent substrate, which is provided with a photocatalyst layer using an anatase-type titanium oxide sol obtained by heating an amorphous titanium peroxide sol at 100 ° C. or higher.

【0013】

Further, in the present invention, a water-repellent coating film is formed on the surface of the base material, and an alkali metal silica compound or an amorphous titanium peroxide sol containing the alkali metal silica compound or amorphous oxidation on the water-repellent coating film. A coating layer using titanium sol or amorphous titanium hydroxide is provided, and a photocatalytic layer using anatase type titanium oxide sol obtained by heating amorphous titanium peroxide sol at 100 ° C. or higher is provided on the coating layer. The present invention relates to a water-repellent substrate, which is characterized by being provided with.

【0014】

Further, in the present invention, a coating layer using an amorphous titanium peroxide sol or an amorphous titanium oxide sol is provided on the surface of the base material, and the amorphous titanium peroxide sol is heated at 100 ° C. or higher on the coating layer. An anatase-type titanium oxide sol thus obtained and a water-repellent agent composed of an alkali metal silica compound or an amorphous titanium peroxide sol containing the alkali metal silica compound, an amorphous titanium oxide sol, an amorphous titanium hydroxide, or the like were used. The present invention relates to a water-repellent substrate characterized in that a photocatalyst layer is provided.

【0015】

Further, according to the present invention, an anatase-type titanium oxide sol obtained by heating an alkali metal silica compound, an amorphous titanium peroxide sol or an amorphous titanium oxide sol, and an amorphous titanium peroxide sol at 100 ° C. or higher on the surface of a base material. The present invention relates to a water-repellent substrate, which comprises providing a photocatalyst layer using and.

【0016】

Further, the present invention comprises the above-mentioned water-repellent substrate having a water contact angle of 80 ° or more and a surface tension of 70 dyne / cm or less on the surface thereof, or a substrate whose surface is inorganic and has pores. In particular, the present invention relates to the above-mentioned water-repellent substrate, which is characterized by being a cement or concrete substrate or a porous rock-based substrate such as sandstone.

【0017】

BEST MODE FOR CARRYING OUT THE INVENTION

The base material used in the surface water-repellent substrate of the present invention includes cement molded products, building materials such as metal tiles, civil engineering / buildings such as concrete, glass products such as glasses and optical lenses, synthetic resin plates, and plastic sheets. Examples of synthetic resin products such as fibers include porous rocks such as cement and sand rock, inorganic materials such as ceramics and glass, and organic materials such as organic polymer resins, rubber, wood, and paper. , And metal materials such as aluminum and steel can be used without limitation. Further, the size and shape of the base material are not particularly limited, and block-shaped, plate-shaped, needle-shaped, honeycomb-shaped, fiber-shaped, filter sheet-shaped, bead-shaped, foam-shaped, or a combination thereof may be used.

【0018】

Among these base materials, an inorganic base material having pores, for example, cement, concrete, GRC (cement hollow extrusion molding material), mortar, tile, brick, porous rock such as sand rock, etc. is used as a base material, and alkali is used. The water-repellent substrate of the present invention using a metallic silica compound or an amorphous titanium peroxide sol containing the alkali metal silica compound, an amorphous titanium oxide sol or an amorphous titanium hydroxide as a water repellent has excellent water repellency. In addition to excellent photocatalytic ability, a strong water absorption prevention layer with excellent durability is formed on the surface of the base material, and as a result, it exhibits excellent effects in preventing deterioration due to salt damage, frost damage, neutralization, etc. and prevention of algae growth. ..

【0019】

When the base material is made of an organic polymer resin material such as a plastic plate and may be deteriorated by the photocatalyst layer, an alkali metal silica compound is placed between the photocatalyst layer and the organic polymer resin base material. A coating layer using a solution, an amorphous titanium peroxide sol containing this alkali metal silica compound, an amorphous titanium oxide sol or a coating layer using an amorphous titanium hydroxide, or an amorphous titanium peroxide sol or an amorphous titanium oxide sol. By interposing the used coating layer as an intermediate layer, or by providing a photocatalyst layer containing an alkali metal silica compound, an amorphous titanium peroxide sol or an amorphous titanium oxide sol, and an anatase type titanium oxide sol as a photocatalyst layer. , Deterioration of the organic polymer resin base material due to the photocatalyst can be prevented. As described above, according to the present invention, the use of the organic polymer resin-based substrate is not restricted as compared with the conventional water-repellent substrate.

【0020】

In the water-repellent coating film of the present invention, in addition to the coating layer formed on the surface of the base material using the water-repellent agent, the surface of the base material itself has water repellency, or the surface of the base material is impregnated with the water-repellent agent. For the sake of convenience, those having water repellency due to a chemical reaction on the surface of the substrate are also included. As the water repellent used for forming the water-repellent coating film, JP-A-7-291667, JP-A-8-143332, JP-A-8-12922, JP-A-9-228073, etc. Any of the above-mentioned conventionally known ones and commercially available ones, regardless of whether they are inorganic or organic water repellents, as long as they show water repellency or hydrophobicity when coated on a substrate. Although it can be used as a water-repellent (hydrophobic) agent, it is desirable that the water-repellent (hydrophobic) ability can be controlled by heat, air or the like.

【0021】

For organic water repellents, for example, organic polymer water repellents, heat treatment or CO in air₂Examples of silicon-based and fluorine-based water repellents that generate a water-repellent function when combined with silane / silicon-based water repellent include methyl-substituted linear dimethylpolysiloxane and dimethylpolysiloxane and methyl. As a fluorine-based agent, a copolymer with hydroxysiloxane is used as a perfluorooctyl acrylate polymer containing a perfluoroalkyl group-containing acrylate polymer as a main component, a chromium-coordinating compound of saturated fluorinated monobasic acid, and polytetrafluoro. Specific examples of the ethylene agent and the like can be given. Moreover, the silicone surface modifier "X-24-7890" manufactured by Shin-Etsu Chemical Co., Ltd. can be exemplified.

【0022】

When a water-repellent coating film is formed using these organic polymer-based water-repellent agents in the water-repellent substrate of the present invention, an alkali is formed between the organic polymer-based water-repellent coating film and the photocatalyst layer. A coating layer using a metal silica compound solution, an amorphous titanium peroxide sol containing this alkali metal silica compound, an amorphous titanium oxide sol or a coating layer using an amorphous titanium hydroxide, or an amorphous titanium peroxide sol or an amorphous type. It is preferable to prevent the organic polymer-based water-repellent coating film from being decomposed and deteriorated by the photocatalyst by interposing a coating layer using titanium oxide sol as an intermediate layer. This intermediate layer blocks the photocatalytic action, but not the water repellent action.

【0023】

Examples of the inorganic water repellent include a solution of an alkali metal silica compound such as potassium silicate, lithium silicate, and sodium silicate, or an amorphous titanium peroxide sol containing these alkali metal silica compounds, an amorphous titanium oxide sol, or an amorphous type. Titanium hydroxide compounds can be exemplified (see Japanese Patent Application No. 9-259495). When an inorganic water repellent composed of these alkali metal silica compound solutions or an inorganic water repellent containing the same is applied to a cement or concrete base material or a porous rock base material such as sand rock, the cement or concrete base material is applied. Alternatively, the water repellent permeates into the pores on the porous surface of porous rocks such as sand rocks, and calcium hydroxide Ca (OH), which is a lime component in concrete, rocks, etc.₂Calcium silicate CaSiO reacts with₂Potassium carbonate K reacts with layers and carbon dioxide in the air₂CO₃A layer and a layer composed of such calcium silicate and potassium carbonate are formed, and a water-repellent coating film having excellent water resistance is formed. Further, as a commercially available product of the inorganic water repellent, "Hydrosum RX" manufactured by Nippon Chemix Co., Ltd. can be specifically exemplified. When these inorganic water repellents are used, unlike the case where the organic polymer water repellent is used, an amorphous titanium peroxide sol or an amorphous titanium oxide sol is formed between the water repellent coating film and the photocatalyst layer. There is no need to provide an intermediate layer.

【0024】

Further, the alkali metal silica compound such as potassium silicate, lithium silicate, and sodium silicate has an action of preventing decomposition / deterioration of the organic polymer material such as the organic polymer-based water-repellent coating film by a photocatalyst. Since it has an effect of enhancing the water-repellent performance of other water-repellent agents, the coating layer containing this alkali metal silica compound may be used as an organic polymer-based water-repellent coating film, an organic polymer-based substrate, and a photocatalyst layer. By interposing it as an intermediate layer between the two, it is possible to prevent decomposition and deterioration of the organic polymer material by the photocatalyst and to obtain a water-repellent substrate having excellent water-repellent performance.

【0025】

The amorphous titanium peroxide sol and the amorphous titanium oxide sol in the present invention do not have a photocatalytic function, but have an ultraviolet absorbing function. On the other hand, the anatase-type titanium oxide sol has a photocatalytic function. These amorphous titanium peroxide sol, amorphous titanium oxide sol and anatase type titanium oxide sol can be produced, for example, as follows.

【0026】

Titanium tetrachloride TiCl₄Ammonia water or alkali hydroxide such as sodium hydroxide is added to the aqueous titanium salt solution such as. The resulting pale bluish white, amorphous titanium hydroxide Ti (OH)₄Is orthotitanium acid H₄TiO₄Also called, when this titanium hydroxide is washed and separated and then treated with hydrogen peroxide solution, an amorphous titanium peroxide solution can be obtained. This amorphous titanium peroxide sol has a pH of 6.0 to 7.0 and a particle size of 8 to 20 nm, and its appearance is a transparent yellow liquid, which is stable even when stored at room temperature for a long period of time. The sol concentration is usually adjusted to 1.40 to 1.60%, but the concentration can be adjusted as needed. When using at a low concentration, dilute with distilled water or the like before use. Further, when this amorphous titanium peroxide sol is heated at room temperature to 100 ° C, a part of it changes to an amorphous titanium oxide sol, and when it is heated at 100 ° C or higher, it gradually becomes an anatase type titanium oxide sol.

【0027】

As described above, the amorphous titanium oxide can be obtained by heating the amorphous titanium peroxide sol as it is at room temperature to 100 ° C, or by coating the amorphous titanium peroxide sol on the substrate and then heating it at about 200 ° C. It can also be obtained by drying and fixing. Further, as the amorphous titanium hydroxide used in the present invention, an amorphous titanium hydroxide solution which is an intermediate product in the manufacturing process of the amorphous titanium peroxide sol can be exemplified.

【0028】

The amorphous titanium peroxide sol and the amorphous titanium oxide sol have not yet crystallized in an amorphous state at room temperature, have excellent adhesion, have high film forming properties, and can produce a uniform and flat thin film. Since the dry film has a property of being insoluble in water, a coating layer can be easily formed at room temperature by using these. As described above, the amorphous titanium peroxide sol and the coating layer using the amorphous titanium oxide sol are decomposed and deteriorated by the photocatalyst of the adjacent lower layer organic polymer resin base material and organic polymer water repellent coating film. In addition to having an action of preventing the above, it can be expressed on the surface of the coating layer without interfering with the water repellency of the water-repellent coating film formed as the lower layer. Further, the coating layer using the mixture of the amorphous titanium peroxide sol or the amorphous titanium oxide sol, the alkali metal silica compound, and the anatase type titanium oxide sol is decomposed by the photocatalyst of the adjacent lower organic polymer resin base material. In addition to having the effect of preventing deterioration, it exhibits excellent water repellency and photocatalytic activity on its surface.

【0029】

In the present invention, the anatase-type titanium oxide sol used for forming the photocatalyst layer can be prepared by heating an amorphous-type titanium peroxide sol at 100 ° C. or higher. As described above, when the amorphous titanium peroxide sol is heated at room temperature to 100 ° C, a part of it changes to an amorphous titanium oxide sol, and when it is heated at 100 ° C or higher, it gradually becomes an anatase type titanium oxide sol. For example, even when the amorphous titanium peroxide sol is heated at 100 ° C or higher, when the heating is performed only for a short time, not all of them become anatase type titanium oxide sol, and the anatase type titanium oxide sol is used. A mixture of amorphous titanium peroxide sol and / or amorphous titanium oxide sol is formed. Since this mixture also has photocatalytic activity, the "anatase-type titanium oxide sol obtained by heating the amorphous titanium peroxide sol at 100 ° C. or higher" in the present invention includes anatase-type titanium oxide sol and amorphous peroxidation for convenience. Mixtures with titanium sol and / or amorphous titanium oxide sol are also included. As described above, the type and properties of the product change depending on the heating temperature and heating time of the amorphous titanium peroxide sol, but when treated at 100 ° C. for 6 hours, most of the product becomes anatase type titanium oxide sol. The properties of this anatase-type titanium oxide sol are pH 7.5 to 9.5, particle size 8 to 20 nm, and its appearance is a yellow-suspended liquid. The sol concentration of this anatase-type titanium oxide sol is usually adjusted to 2.70 to 2.90% by weight, but the concentration can be adjusted and used as needed. Further, the anatase-type titanium oxide sol can be made into anatase-type titanium oxide by coating an amorphous titanium peroxide sol on a substrate and then drying and fixing the sol by heating it to about 200 ° C. or higher.

【0030】

A major feature of the present invention is the use of this anatase-type titanium oxide sol. By using this anatase-type titanium oxide sol for forming the photocatalyst layer, the water-repellent performance of the water-repellent coating film or the like formed as the lower layer is exhibited on the surface of the water-repellent substrate without being hindered by the photocatalyst layer. Further, in the present invention, other photocatalysts and electron-capturing metals can be contained in the anatase-type titanium oxide sol as long as the characteristics of the anatase-type titanium oxide sol are not impaired. This anatase-type titanium oxide sol has excellent adhesion, high film-forming property, a uniform and flat thin film can be produced, and the dry film has the property of being insoluble in water, so that the coating layer can be formed at room temperature. Since it can be easily formed and does not require heating at 200 to 300 ° C for film formation, not only does it not reduce the water repellency of the water repellent coating film due to heating, but also the cement or concrete surface. Alternatively, it can be directly applied to the outer surface of existing building materials, civil engineering, buildings, monuments, etc. that have a porous rock surface such as sand rock.

【0031】

Further, in the present invention, as a coating method for forming a water-repellent coating film or an amorphous titanium peroxide sol or anatase type titanium oxide sol, a method of forming a thin film by a method such as spray coating, dipping or spin coating can be mentioned. The thickness of the coating layer is determined by the thickness at which the functions of each layer can be achieved, such as imparting water repellency, blocking photocatalytic activity, and developing photocatalytic activity, and the film-forming performance of each coating agent.

【0032】

Schematic diagrams of the structure of the water-repellent substrate of the present invention are shown in FIGS. 1 to 6, but the present invention is not limited thereto. In FIG. 1, a water-repellent coating film 2 using an alkali metal silica compound solution is provided on the surface of the inorganic base material 1, and a photocatalyst layer 3 using anatase-type titanium oxide sol is provided on the surface of the water-repellent coating film 2. The provided water repellent substrate of the present invention is shown. In FIG. 2, an organic polymer-based water-repellent coating film 4 is provided on the surface of the inorganic base material 1, and a coating layer 5 using an amorphous titanium peroxide sol is provided on the water-repellent coating film 4. , The water-repellent substrate of the present invention provided with a photocatalyst layer 3 using an amorphous titanium oxide sol is shown on the upper surface of the coating layer 5. In FIG. 3, an organic polymer-based water-repellent coating film 4 is provided on the surface of the inorganic base material 1, and a coating layer 2 using an alkali metal silica compound solution is provided on the water-repellent coating film 4. The water-repellent substrate of the present invention provided with a photocatalyst layer 3 using an anatase-type titanium oxide sol is shown on the upper surface of the coating layer 2.

【0033】

Further, in FIG. 4, an organic polymer-based water-repellent coating film 4 is provided on the surface of the inorganic base material 1, and an amorphous titanium peroxide sol containing an alkali metal silica compound is placed on the water-repellent coating film 4. The used coating layer 6 is provided, and the water-repellent substrate of the present invention provided with the photocatalyst layer 3 using an amorphous titanium oxide sol is shown on the upper surface of the coating layer 6. In FIG. 5, a coating layer 5 using an amorphous titanium peroxide sol is provided on the surface of the organic polymer resin base material 7, and the coating layer 5 is composed of an anatase type titanium oxide sol and an alkali metal silica compound. The water-repellent substrate of the present invention provided with the photocatalyst layer 8 using the water-repellent agent is shown. FIG. 6 shows the water-repellent substrate of the present invention in which a photocatalyst layer 9 using an alkali metal silica compound, an amorphous titanium peroxide sol, and an anatase type titanium oxide sol is provided on the surface of an organic polymer resin base material 7. Has been done.

【0034】

The surface water-repellent substrate having the photocatalyst layer of the present invention has excellent water-repellent (hydrophobic) performance and antifouling function by the photocatalyst when irradiated with ultraviolet rays, and cannot exhibit the antifouling function by the photocatalyst when not irradiated with ultraviolet rays. It has the feature of having excellent water repellency. In the case of the water-repellent substrate of the present invention, there is a function of blocking deterioration due to the photocatalytic function between the photocatalyst layer having photocatalytic activity and the organic polymer resin water-repellent coating film or the organic polymer resin substrate. A coating layer containing an amorphous titanium peroxide sol and / or an amorphous titanium oxide sol, a coating layer using an alkali metal silica compound solution, an amorphous titanium peroxide sol containing an alkali metal silica compound, and an amorphous titanium oxide sol. Alternatively, since there is a coating layer using amorphous titanium hydroxide, excellent water repellency and antifouling function are maintained for a long time without deterioration of the organic polymer resin water-repellent coating film and the organic polymer resin base material. Maintained over.

【0035】

As described above, the excellent water-repellent (hydrophobic) performance of the water-repellent substrate of the present invention is obtained when the water-repellent performance of the lower layer is expressed on the surface through the photocatalyst layer or when the water-repellent agent is mixed with the photocatalyst layer. It appears on the surface of the photocatalyst layer and repels rainwater and the like, but does not have an oil-repellent effect on oil and the like. Such water repellency and oil repellency are said to be determined by the strength of the interaction between the solid and the liquid, that is, the amount of the solid / liquid interfacial tension, and the surface tension of the liquid (rc) is higher than the critical surface tension (rc) of the solid. When r) is large (rc <r), the surface of the substrate exhibits water repellency and oil repellency. For example, a substrate treated with an alkali metal silicic acid compound-based water repellent, a paraffin-based water repellent, or a silicon-based water repellent having a critical surface tension (rc) of about 24 to 26 dyne / cm has a surface tension of 72 dyne /. It has a water-repellent effect on water of cm and rainwater of 53 dyne / cm, but has no oil-repellent effect on gasoline with a surface tension of 22 dyne / cm, and these adhere to the surface of the substrate. It causes dirt. Further, the oil film adhering to the surface of the rainwater droplet remains slightly when the water droplet is removed from the water-repellent substrate, and the accumulation of this oil film also causes stains. However, the water-repellent substrate of the present invention has water-repellent performance. Since it also has a photocatalytic function, contaminated organic substances such as oil and dirt adhering to the surface of the substrate can be decomposed by photocatalytic action.

【0036】

Further, when a solid, a liquid and its saturated vapor are brought into contact with each other, the contact angle defined as the angle between the tangent line drawn on the liquid at the three-phase contact point and the solid surface on the side containing the liquid is also the substrate. It is usually used as a standard for expressing the water-repellent performance of a water-repellent substrate, similar to the critical surface tension of. The water-repellent substrate of the present invention preferably has a water contact angle of 80 ° or more, preferably 90 ° or more, and a surface tension of 70 dyne / cm or less, preferably 50 dyne / cm or less on the surface thereof.

【0037】

[Example]

Hereinafter, the present invention will be described in more detail with reference to examples, but the technical scope of the present invention is not limited to these examples. Reference Example 1 (Manufacturing of amorphous titanium peroxide sol) Titanium tetrachloride TiCl₄50% solution (Sumitomo Citics Co., Ltd.) diluted 70 times with distilled water and ammonium hydroxide NH₄A 25% solution of OH (Takasugi Pharmaceutical Co., Ltd.) diluted 10-fold with distilled water is mixed at a volume ratio of 7: 1 to carry out a neutralization reaction. After the neutralization reaction, adjust the pH to 6.5 to 6.8, leave it for a while, and then discard the supernatant. Remaining Ti (OH)₄Add about 4 times the amount of distilled water in the gel, stir well and leave. Check with silver chloride and repeat washing with water until no chlorine ions are detected in the supernatant. Finally, discard the supernatant and leave only the gel. In some cases, dehydration can be performed by centrifugation. This pale bluish white Ti (OH)₄To 3600 ml, 210 ml of 35% hydrogen peroxide solution is added in two portions every 30 minutes, and the mixture is stirred at about 5 ° C overnight to obtain about 2500 ml of a yellow transparent amorphous titanium peroxide sol. In the above steps, if heat generation is not suppressed, water-insoluble substances such as metatitanic acid may precipitate, so it is desirable to suppress heat generation in all steps.

【0038】

Reference Example 2 (Manufacturing of anatase-type titanium oxide sol) When the amorphous titanium peroxide sol is heated at 100 ° C., anatase-type titanium oxide is produced after about 3 hours, and when it is heated for about 6 hours, anatase-type titanium oxide sol is obtained. In addition, when heated at 100 ° C for 8 hours, it becomes pale yellow and slightly suspended fluorescence, and when concentrated, a yellow-opaque one is obtained, and when heated at 100 ° C for 16 hours, a very pale yellow one is obtained. The degree of dry adhesion is slightly lower than that of the above-mentioned one heated at 100 ° C for 6 hours. Since this anatase-type titanium oxide sol has a lower viscosity than the amorphous-type titanium peroxide, it can be concentrated to about 2.5% by weight for easy dipping.

【0039】

(Preparation of water repellent substrate) Example 1 0.05 g of a water repellent containing 7.4% by weight of potassium silicate was uniformly applied to the surface of a 100 × 100 × 2 mm glass plate, dried at 100 ° C, and then manufactured according to Reference Example 2 on it. Anatase-type titanium oxide sol (TiO₂0.4 g of a 2-fold diluted product (containing 1.7% by weight) was uniformly applied and dried at 28 ° C. to prepare the water-repellent substrate of the present invention. For application, use Meiji Machine Co., Ltd.'s spray gun FS-G05R-1 with a 0.54 mm diameter round blowout nozzle at 2 kg / cm.³Used with the air pressure of (the same applies hereinafter).

【0040】

Example 2 0.4 g of silicone surface modifier "X-24-7890" manufactured by Shin-Etsu Chemical Co., Ltd. was uniformly applied to the surface of the above glass plate, dried at 28 ° C, and then manufactured in Reference Example 1 on it. Amorphous titanium peroxide sol (TiO)₃0.2 g of a 2-fold diluted product (containing 1.7% by weight) is uniformly applied, dried at 28 ° C, and then the above-mentioned anatase-type titanium oxide sol (TiO) is further applied.₂0.4 g of a 2-fold diluted product (containing 1.7% by weight) was uniformly applied and dried at 28 ° C. to prepare the water-repellent substrate of the present invention.

【0041】

Comparative Examples 1 and 2 On the surface of the glass plate, the anatase-type titanium oxide sol (TiO)₂0.4 g of a 2-fold diluted product (containing 1.7% by weight) was uniformly applied, dried at 28 ° C, and then 0.05 g and 0.1 of the above water repellent containing 7.4% by weight of potassium silicate were added thereto. g was uniformly applied and dried at 100 ° C. to prepare water-repellent substrates of Comparative Examples 1 and 2.

【0042】

Example 3 0.9 g of a water repellent containing 7.4% by weight of potassium silicate is uniformly applied to the surface of a 300 x 300 x 10 mm GRC (cement hollow extrusion molding material: manufactured by Showa Denko KK) and dried at 28 ° C. Later, on top of that, the above-mentioned anatase-type titanium oxide sol (TiO)₂As a result, 0.6 g of a 2-fold diluted product (containing 1.7% by weight) was uniformly applied and dried at 28 ° C. to prepare the water-repellent substrate of the present invention.

【0043】

Example 4 300 × 300 × 24 mm Indian sandstone (for walls) On the surface of the building material, the above-mentioned mosquitoes 1.2g / 100cm water repellent containing 7.4% by weight of rum²After applying evenly at the ratio of, and drying at 28 ° C, the above anatase-type titanium oxide sol (TiO) is placed on it.₂As a 2-fold diluted solution containing 1.7% by weight) 0.8g / 100cm²The water-repellent substrate of the present invention was prepared by uniformly applying the mixture and drying at 28 ° C.

【0044】

(Water repellency test) On the test substrates prepared in Examples 1 to 4 and Comparative Examples 1 and 2, 0.1 ml of tap water was dropped from a height of 1 cm with a dropper, left for about 10 minutes, and then the substrate. This was done by measuring the contact angle of the water droplets above. The results are shown in Table 1.

【0045】

(Photocatalyst performance test) A 20-fold diluted solution of commercially available red ink (manufactured by Pilot Co., Ltd.) was applied by spraying onto the test substrates prepared in Examples 1 to 4 and Comparative Examples 1 and 2 on the substrate surface. The time to decolorization was measured outdoors under cloudy, 28 ° C climatic conditions. The results are shown in Table 1.

【0046】

[table 1]

<img file="JP2000135442A_D0001.tif" />【0047】

As can be seen from the water repellency test in Table 1, the substrates prepared in Examples 1 to 4 and Comparative Examples 1 and 2 all have a contact angle of more than 90 ° and show excellent water repellency. However, in the photocatalyst performance test by the organic matter decomposition reaction using red ink, the water-repellent substrates of Examples 1 to 3 of the present invention having a photocatalyst layer on the surface layer are comparative examples having a water-repellent coating film on the surface layer. It was found that the decoloring time of the red ink was 1/4 faster than that of the substrate of the above, and the water-repellent substrate of the present invention was remarkably superior in photocatalytic performance.

【0048】

[Effect of the invention]

The water-repellent substrate of the present invention has an extremely excellent water-repellent function and a photocatalytic function, and has both an antifouling effect and a dew-proofing effect. Further, the water-repellent substrate of the present invention is not deteriorated by the photocatalytic action even if the water-repellent coating film is made of an organic polymer resin, and also has a photocatalytic action even if the base material is an organic polymer resin base material. According to the present invention, the use of the organic polymer resin-based material is not restricted in the water-repellent coating film or the base material because it is not deteriorated by the above. Further, in the present invention, an inorganic base material having pores such as concrete, rocks such as sandstone, etc. is used as the base material, and an alkali metal silica compound or an amorphous titanium peroxide sol containing the alkali metal silica compound as a water repellent agent, etc. In addition to excellent water repellency and photocatalytic ability, a strong water absorption prevention layer with excellent durability is formed on the surface of the base material, resulting in prevention of deterioration due to salt damage, frost damage, neutralization, etc. It has an excellent effect on preventing the growth of algae.

[Simple explanation of drawings]

[Figure 1]

It is a schematic diagram which shows the water-repellent substrate of this invention.

[Figure 2]

It is a schematic diagram which shows the water-repellent substrate of the different aspect of this invention.

[Fig. 3]

It is a schematic diagram which shows the water-repellent substrate of the different aspect of this invention.

[Fig. 4]

It is a schematic diagram which shows the water-repellent substrate of the different aspect of this invention.

[Fig. 5]

It is a schematic diagram which shows the water-repellent substrate of the different aspect of this invention.

[Fig. 6]

It is a schematic diagram which shows the water-repellent substrate of the different aspect of this invention.

[Simple description of the code]

1 Inorganic base material 2 Water-repellent coating film or coating layer using alkali metal silica compound solution 3 Photocatalytic layer using anatase-type titanium oxide sol 4 Organic polymer water-repellent coating film 5 Coating layer using amorphous titanium peroxide sol 6 Coating layer using amorphous titanium peroxide sol containing alkali metal silica compound 7 Organic polymer resin base material 8 Photocatalytic layer using a water repellent composed of anatase-type titanium oxide sol and alkali metal silica compound 9 Photocatalytic layer using amorphous titanium peroxide sol and anatase type titanium oxide sol