Coating agent for forming inorganic film, method of producing the same and method of forming the same inorganic film

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention provides an inorganic film that provides a titanium oxide film having excellent photoactivity, antibacterial property, hydrophilicity, stain resistance, antifogging property, gas decomposition property, deodorizing property, water treatment property, energy conversion property, decolorization property and the like. The present invention relates to a coating agent for forming, a method for producing a coating agent for forming an inorganic film, and a method for forming an inorganic film.

【0002】

[Conventional technology and its problems]

Conventionally, as a method of forming a titanium oxide film, (1) a method of applying titanium oxide sol to a base material and then sintering it, and (2) a method of applying an aqueous solution of titanium chloride or titanium sulfate to a base material and then heat-treating it. , (3) Plasma spraying method in which solid particles are melted in plasma generated in the atmosphere and struck on the surface of the substrate, (4) Oxide target is sputtered in vacuum to form a film on the substrate. Sputtering method, (5) CVD method in which organic metal compounds are volatilized and decomposed in an electric furnace to form a film on the substrate, (6) Sol obtained by hydrolysis of metal alkoxide is applied to the substrate. , Sol-gel method of sintering and the like.

【0003】

However, in the above method, (1) is inferior in film-forming property because cracking and peeling occur at a film thickness of 0.1 μm or more, and it is necessary to sinter at a temperature of several hundred degrees or more, which is troublesome. 2) has an adverse effect on the base material due to thermal decomposition products, and it is necessary to sinter at a temperature of several hundred degrees or more, which is troublesome. In (4) and (5), a good film cannot be obtained unless the pressure is reduced, and a reaction vessel capable of vacuum exhaust is required. Generally, the film formation rate is slow, and several hundred degrees or more is required to obtain a dense film. The substrate must be heated, acid, alkali or organic matter is added to the sol of (6), and there is a problem of corrosion of the material to be coated, and the temperature for removing the organic matter (400 ° C or higher) ) Was needed.

【0004】

In addition, as a method that does not include the step of high-temperature sintering, which is the above-mentioned drawback, (7) forming a titanium oxide film from a fluoride aqueous solution of titanium oxide and boric acid, (8) titanium chloride or titanium sulfate aqueous solution and ammonia, etc. A method of precipitating titanium hydroxide gel from an alkaline solution such as caustic soda, then separating the titanium hydroxide gel by decantation, washing thoroughly with water, and further adding aqueous hydrogen peroxide solution (see JP-A-9-71418) is known. Has been done. However, (7) requires a long time to form a film, the handling of fluoride is troublesome, and (8) is a complicated process and troublesome removal of alkali salts. There are drawbacks such as it is difficult to obtain a high-purity product that is easily mixed with other metals, and it is difficult to control the PH, and the product obtained differs depending on the fluctuation.

【0005】

An object of the present invention is to provide a coating agent for forming an inorganic film, a method for producing the same, and a method for forming an inorganic film, which solves the above-mentioned problems.

【0006】

[Means for solving problems]

As a result of intensive research to achieve the above object, the present inventor peroxidizes a titanium monomer containing a group that hydrolyzes to a hydroxyl group and / or a low condensate thereof, particularly in the presence of titanium oxide sol. It has been found that the coating agent for forming an inorganic film obtained by reacting with hydrogen peroxide and the coating agent for forming an inorganic film formed by heat modification thereof eliminate all the conventional drawbacks, and have completed the present invention. That is, the present invention is characterized in that it is obtained by reacting a titanium monomer containing a group that hydrolyzes to a hydroxyl group and / or a low condensate thereof with a hydrogen peroxide solution in the presence of a titanium oxide sol. It is characterized in that a coating agent for film formation, a titanium monomer containing a group that hydrolyzes to a hydroxyl group and / or a low condensate thereof is reacted with a hydrogen peroxide solution within a reaction temperature range of 1 to 70 ° C. A method for producing an inorganic film-forming coating agent, an inorganic film-forming coating agent obtained by heat-modifying the inorganic film-forming coating agent, and the inorganic film-forming coating agent are applied or impregnated into a base material, and dried or heat-treated. It relates to a method for forming an inorganic film, which is characterized by being formed by.

【0007】

BEST MODE FOR CARRYING OUT THE INVENTION

The coating agent for forming an inorganic film of the present invention is obtained by reacting a titanium monomer containing a group that hydrolyzes to a hydroxyl group and / or a low condensate thereof with a hydrogen peroxide solution in the presence of a titanium oxide sol. Is.

【0008】

The titanium oxide sol used in the present invention is a sol in which atypical titania and anatas-type titania fine particles are dispersed in water (for example, an aqueous organic solvent such as alcohol or alcohol ether may be contained if necessary). Is.

【0009】

As the above-mentioned titanium oxide sol, conventionally known ones can be used. Examples of the titanium oxide sol include (1) one obtained by hydrolyzing a titanium-containing solution such as titanium sulfate and titanyl sulfate, and (2) one obtained by hydrolyzing an organic titanium compound such as titanium alkoxide. 3) Atypical titania sol in which titanium oxide aggregates such as those obtained by hydrolyzing or neutralizing a titanium halide solution such as titanium tetrachloride are dispersed in water or the titanium oxide aggregates are fired to produce anatas-type titanium fine particles. Titanium can be used by dispersing it in water. Amorphous titania can be converted into anatase-type titania by firing at a temperature equal to or higher than the crystallization temperature of anatase, for example, 400 ° C to 500 ° C or higher. Examples of the aqueous sol of titanium oxide include TKS-201 (manufactured by TAYCA Corporation, trade name, Anatas type crystal form, average particle size 6 nm), TA-15 (manufactured by Nissan Chemical Co., Ltd., trade name, etc.). Anatas type crystal form), STS-11 (manufactured by Ishihara Sangyo Co., Ltd., trade name, Anatas type crystal form) and the like.

【0010】

The weight ratio of the titanium oxide sol to the titanium hydrogen peroxide reactant when used for reacting the titanium monomer or its condensate with the hydrogen peroxide solution is 1/99 to 99/1, preferably about 10/90. It is in the range of ~ 90/10. If the weight ratio is less than 1/99, the effect of adding the titanium oxide sol such as stability and photoreactivity is not observed, and if it exceeds 99/1, the film forming property is deteriorated, which is not preferable.

【0011】

As the titanium monomer containing a group that hydrolyzes to a hydroxyl group, the general formula Ti (OR) is particularly used.₄ Tetraalkoxy titanium (in the formula, R represents the same or different alkyl group having 1 to 5 carbon atoms) is preferable. Examples of the alkyl group having 1 to 5 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl group, a sec-butyl group and a tert-butyl group. Can be mentioned.

【0012】

Further, as a low condensate of a titanium monomer containing a group that hydrolyzes into a hydroxyl group, the above-mentioned Ti (OR) is particularly suitable.₄ Compounds having a degree of condensation of 2 to 30 can be used, and those having a degree of condensation of 2 to 10 are particularly preferable. The mixing ratio of a titanium monomer containing a group that hydrolyzes to a hydroxyl group and / or a low condensate thereof (hereinafter, these are simply abbreviated as "hydrolyzable titanium") and a hydrogen peroxide solution is hydrolyzed. It is preferably in the range of 0.1 to 100 parts by weight, particularly 1 to 20 parts by weight, in terms of hydrogen peroxide with respect to 10 parts by weight of sex titanium. If it is less than 0.1 parts by weight in terms of hydrogen peroxide, chelate formation is not sufficient and white turbid precipitation occurs. On the other hand, if it exceeds 100 parts by weight, unreacted hydrogen peroxide tends to remain and dangerous active oxygen is released during storage, which is not preferable.

【0013】

The hydrogen peroxide concentration of the hydrogen peroxide solution is not particularly limited, but it is preferably in the range of 3 to 30 weights in terms of ease of handling and the solid content of the product liquid related to coating workability. Further, the coating agent for forming an inorganic film of the present invention can be produced by reacting hydrolyzable titanium with a hydrogen peroxide solution within a reaction temperature range of 1 to 70 ° C for 10 minutes to 20 hours.

【0014】

In the coating agent for forming an inorganic film of the present invention, by reacting hydrolyzable titanium with hydrogen peroxide solution, the hydrolyzable titanium is hydrolyzed with water to produce a hydroxyl group-containing titanium compound, and then hydrogen peroxide is generated. It is presumed that it coordinates with the produced hydroxyl group-containing titanium compound, and it was obtained by this hydrolysis reaction and coordination with hydrogen peroxide occurring near the same time. It is extremely stable in the room temperature range and has a long period of time. Produces a chelating solution that can withstand storage. The titanium hydroxide gel used in the conventional manufacturing method is partially three-dimensionalized by a Ti-O-Ti bond, and the composition and stability of this gel and the reaction of hydrogen peroxide solution are essentially different. Further, if titanium oxide sol is added in advance, it is possible to prevent a partial condensation reaction from occurring during synthesis and thickening. It is considered that the reason is that the condensation reaction product is adsorbed on the surface of the titanium oxide sol and prevents polymerization in the solution state. A dense titanium oxide film having excellent adhesiveness can be formed by applying the coating agent for forming an inorganic film of the present invention on a substrate, drying it, or heat-treating it at a low temperature. A titanium oxide film can be formed even at a low temperature, but a treatment temperature of 200 ° C. or higher is preferable in order to improve adhesion. Further, a film having excellent adhesion can be formed without peeling off a titanium oxide film having a thickness of 1 μm or more with one application, but the film thickness is usually preferably in the range of 0.001 to 10 μm, particularly 0.1 to 1 μm. The coating agent for forming an inorganic film of the present invention forms a film containing amorphous titanium oxide containing a small amount of hydroxyl groups at a temperature lower than 200 ° C, but forms a dense crystalline titanium oxide film at a temperature of 200 ° C or higher. Form.

【0015】

When the amount of titanium oxide sol is large, a crystalline titanium oxide film can be formed just by applying it, which is useful as a coating material for a material that cannot be heat-treated. In such a method, a product that can be used for the above-mentioned various uses, has a relatively high density, and has good adhesion can be obtained at a low temperature. The film that has just been dried is water resistant but also invasive, and by impregnating with another compound solution and then heat-treating, a complex in which other substances are supported or dispersed is formed in the titanium oxide film. It is also possible to do. As other substances, for example, other metal compounds can be used.

【0016】

Other pigments and sol can be added and dispersed later to the above-mentioned coating agent for forming an inorganic film. Examples of the additive include commercially available titanium oxide sol and titanium oxide powder.

【0017】

The base material that can be used in the present invention can be applied to any material that can withstand heat treatment according to the application, such as metal, ceramics, plastics, fibers, glass, and concrete, and is a porous body. It is also possible to perform surface treatment on the inside of the concrete and powder. Many of the titanium oxide films obtained by the present invention are activated by light irradiation. For example, nitrogen oxides and the like can be oxidized to nitric acid. Further, the titanium oxide film obtained by the present invention can be used as a heat-resistant and anticorrosion coating film because it can form a film having excellent heat resistance and corrosion resistance in addition to its photoactive properties.

【0018】

Utilizing the photoactive properties of titanium oxide as described above, for example, decomposition and removal of environmental pollutants in air and water, hydrophilic treatment, antibacterial treatment, deodorization, antifogging property, water treatment, energy conversion property, etc. It can be used in the field of.

【0019】

[Example]

Next, the present invention will be described in detail with reference to examples. The present invention is not limited to the examples described below. In addition, "part" and "%" described in Examples and Comparative Examples are based on weight. Example 1 A mixture of 10 parts of tetra iso-propoxytitanium and 10 parts of iso-propanol is 5 parts (solid content) of TKS-201 (manufactured by TAYCA Corporation, titanium oxide sol), 10 parts of 30% hydrogen peroxide solution, 100 parts of deionized water. It was added dropwise to the mixture of parts at 10 ° C for 1 hour with stirring. Then, it was aged at 10 ° C. for 24 hours to obtain a yellow transparent, slightly viscous coating agent for forming an inorganic film.

【0020】

Example 2 A coating agent for forming an inorganic film was obtained under the same production conditions by using tetra n-butoxytitanium instead of the tetraiso-propoxytitanium of Production Example 1.

【0021】

Example 3 A coating agent solution for forming an inorganic film was obtained under the same production conditions using a tetraiso-propoxytitanium trimer instead of the tetraiso-propoxytitanium of Example 1.

【0022】

Example 4 In Example 1, a three-fold amount of hydrogen peroxide solution was added dropwise at 10 ° C for 1 hour, and the mixture was further aged at 10 ° C for 30 hours to obtain a coating agent for forming an inorganic film.

【0023】

Comparative example 1 A mixture of 10 parts of tetra iso-propoxytitanium and 10 parts of iso-propanol was added dropwise to a mixture of 10 parts of 30% hydrogen peroxide solution and 100 parts of deionized water at 10 ° C. for 1 hour with stirring. Then, it was aged at 10 ° C. for 24 hours to obtain a yellow transparent, slightly viscous coating agent for forming an inorganic film. When the coating liquids for forming the inorganic film of Examples 1 to 4 and Comparative Example 1 were concentrated to a titanium oxide concentration of 5%, Comparative Example 1 solidified into a paste, but Production Examples 1 to 4 were fluid liquids. It was.

【0024】

The coating film was formed by the following method. The coating agent for forming an inorganic film of Examples 1 to 4 and the coating agent for forming an inorganic film of Comparative Example 1 are coated on a mild steel plate with a bar coater so that the dry film thickness is 0.3 μm, and baked at 100 ° C. for 30 minutes. It was. Storage stability (1) of the coating agent for forming an inorganic film of Examples 1 to 4 and the coating agent for forming an inorganic film of Comparative Example 1, and a coating film state (2) and adhesiveness using a coating plate formed under the above conditions. (3), pencil hardness (4), water resistance (5), and water wettability (water contact angle) (6) were tested, and the results are summarized in Table 1.

【0025】

[table 1]

<img file="JP2001089141A_D0001.tif" />【0026】

(1) Storage stability: Viscosity changes and sedimentation after 100 hours of storage at 50 ° C were investigated (compared to the initial ones). (2) Coating film condition: The presence or absence of coating film abnormalities such as smoothness, transparency, and film-forming property (cracking, etc.) of the coating film was observed. (3) Adhesiveness: According to the JIS K-5400 8.5.2 (1990) grid-tape method, 100 squares of 1 mm x 1 mm were created, and the tape was adhered to the surface and peeled off. I checked the number of remaining squares. (4) Pencil hardness: A pencil scratch test specified in JIS K-5400 8.4.2 (1990) was conducted and evaluated by scratches. (5) Water resistance: After immersing in water at 20 ° C for 7 days, the appearance of the coating film was visually observed. (6) Water wettability: The water contact angle on the coating film surface was measured. After irradiating a 4KW high-pressure mercury lamp at a distance of 30 cm from the coating film surface for 10 minutes, the water contact angle was measured. The water contact angle was 0.03 cc of deionized water droplets formed on the test coating plate at 20 ° C, and the contact angle of the water droplets was measured by Kyowa Kagaku Co., Ltd.'s Contactan Gourmet-DCCA type.

【0027】

[Effect of the invention]

In the production method of the present invention, a titanium monomer and / or a low condensate thereof containing a group that hydrolyzes into a hydroxyl group in the presence of a titanium oxide sol is reacted with a hydrogen peroxide solution to cause the titanium monomer and / or The components of the low condensate are adsorbed on the titanium oxide sol particles of the titanium oxide sol, and the adsorbed titanium monomer and / or the low condensate reacts on the surface of the particles to react with the hydroxyl groups on the surface of the particles, and the titanium monomer and / or Alternatively, it chemically bonds with the low condensate thereof, and the titanium monomer and / or the low condensate product itself is also condensed and polymerized on the particle surface, so that there is no gelation or thickening, and the coating is stable and without production variation. A coating agent (titanium sol solution) having excellent film performance can be produced. Naturally, the titanium oxide sol alone is inferior in film-forming property, and even if a titanium hydrogen peroxide complex is added later, the compatibility is low and the film-forming property is not so improved. Further, in the production method of the present invention, only the titanium hydrogen peroxide complex formed by the reaction of the titanium monomer and / or its low condensate with the hydrogen peroxide solution forms only atypical titanium oxide when the coating film is dried at a low temperature. However, when anatase-type titanium oxide sol is used as the sol, it exhibits a function as a photocatalyst even when the coating film is dried at a low temperature. This product can be used in fields such as corrosion resistance and fields utilizing the photocatalytic activity of the titanium oxide film.