JP2010115581A - Photocatalyst supporting member and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photocatalyst supporting member with superior photocatalytic performance, initial antifouling performance, abrasion resistance and surface hardness, wherein a base material like soda lime glass is used allowing easy elution of alkali metal ions and/or alkaline earth metal ions. <P>SOLUTION: The photocatalyst supporting member includes: the base material with a total ion elution amount of 1.0 μg/cm<SP>2</SP>or more, found by measuring the amount of the alkali metal ions and/or alkaline earth metal ions in distilled water obtained by soaking three sample plates of 6 cm×6 cm×2 mm in 250 g of distilled water at 80°C for 24 hours by the atomic absorption spectrometry; a precoat layer formed by applying a precoat composition having polysilazane or a modified matter thereof as a principal component on the base material and curing it; and a photocatalyst-containing layer formed by applying to the precoat layer, thin flake-like titanic acid obtained by applying a basic compound having an interlayer swell action to layered titanium acid and swelling or exfoliating the layers, followed by heat-treating. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a photocatalyst-supporting member using a base material from which alkali metal ions and / or alkaline earth metal ions such as soda-lime glass are easily eluted, and a method for producing the same.

  Functional glass is known in which titanium oxide is coated on the glass surface to provide photocatalytic and superhydrophilic capabilities.

Glass is classified according to differences in main components and the like, and each has different properties. For example, silicate glass and borosilicate glass are special-purpose glasses that have high heat resistance and are used in laboratory equipment, and because of their high melting temperature, high energy is required during molding, making mass production possible. Have difficulty. On the other hand, general-purpose soda-lime glass can be melt-processed at low temperatures by including Na ₂ O or CaO. Therefore, chemical durability such as water resistance and acid resistance is low. In addition, there is a disadvantage that alkali metal ions and / or alkaline earth metal ions, particularly sodium ions, contained in the glass are eluted.

  A method of coating photocatalytic ability by coating titanium oxide on a substrate such as glass is known. In Patent Document 1, a coating film-forming composition containing polysilazane or a modified product thereof as a main component is applied on a base material, cured, and then further treated with high-temperature water. It is disclosed that a siliceous ceramic layer is formed and a photocatalyst-containing layer containing titanium oxide is formed on the siliceous ceramic layer. By treating with high temperature water, components such as ammonia remaining in the siliceous ceramic layer are removed, and the adhesion between the silica ceramic layer and the photocatalyst containing layer is improved.

  However, since particulate titanium oxide is used as a photocatalyst, it has a photocatalytic ability, but there is a problem that the surface of the coating film is not smooth and many initial contaminants are deposited. In addition, when the photocatalyst-containing layer is formed using only the titanium oxide sol, the adhesion and wear resistance are inferior. Therefore, it is necessary to form the photocatalyst-containing layer using a binder such as a silicone compound.

  In Patent Document 2, a photocatalytic hydrophilic member having good abrasion resistance can be obtained by forming a photocatalyst-containing layer containing plate-like photocatalytic metal oxide particles and silica or a silicone precursor. It is disclosed.

  In Patent Document 3, a coating material containing scaly titanium oxide fine particles obtained by ion-exchange treatment of layered titanate with alkylammonium, and silicon oxide or titanium oxide sol as a binder, It is disclosed that it is formed by coating on a base material made of borosilicate glass or the like.

  However, in the above Patent Documents 1 to 3, when a base material from which alkali metal ions and / or alkaline earth metal ions such as soda lime glass are easily eluted, alkali metal ions and / or / Or the influence by alkaline-earth metal ion is not considered.

In Patent Document 4, when soda lime glass is used as a substrate, a SiO ₂ film containing Al ₂ O ₃ is formed as a first layer on the surface of the substrate, and a _second layer is formed thereon. A photocatalytic glass for forming a film mainly composed of TiO ₂ is disclosed. It is said that by providing an Al ₂ O ₃ —SiO ₂ film on the base material, diffusion of sodium ions from the base material can be prevented and the photocatalytic function can be sufficiently exhibited.

However, when flaky titanic acid obtained by swelling or peeling between layers by allowing a basic compound having an interlayer swelling action to act on layered titanic acid is used as a photocatalyst, sufficient photocatalytic ability is obtained even by such a method, Initial antifouling ability, abrasion resistance, and surface hardness could not be obtained.
JP 2001-335950 A Japanese Patent Laid-Open No. 11-76834 JP 2005-290369 A Japanese Patent Laid-Open No. 11-60281

  An object of the present invention is to provide a photocatalytic ability, initial antifouling ability, wear resistance, and surface of a photocatalyst carrying member using a base material from which alkali metal ions and / or alkaline earth metal ions such as soda lime glass are easily eluted. The object is to provide a photocatalyst-supporting member having excellent hardness and a method for producing the same.

In the photocatalyst carrying member of the present invention, three sample plates each having a size of 6 cm × 6 cm × 2 mm are immersed in 250 g of distilled water at 80 ° C. for 24 hours, and the amounts of alkali metal ions and alkaline earth metal ions in the distilled water are determined. A base material having a total ion elution amount determined by measurement by atomic absorption analysis of 1.0 μg / cm ² or more and a precoat composition mainly composed of polysilazane or a modified product thereof are applied onto the base material, After applying a precoat layer formed by curing and flaky titanic acid obtained by swelling or peeling between layers by allowing a basic compound having an interlayer swelling action to act on layered titanic acid on the precoat layer And a photocatalyst-containing layer formed by heat treatment.

The base material used in the present invention has a total ion elution amount of the above alkali metal ions and alkaline earth metal ions of 1.0 μg / cm ² or more. Here, the alkali metal ions are lithium ions, sodium ions, and potassium ions, and the alkaline earth metal ions are beryllium ions, magnesium ions, and calcium ions. In the present invention, when a base material having a high total elution ion amount of alkali metal ions and alkaline earth metal ions is used, the total ion elution amount of alkali metal ions and alkaline earth metal ions eluted from the base material, particularly By reducing the influence of the amount of sodium ion elution ions on the photocatalyst containing layer, the photocatalyst carrying member is excellent in photocatalytic ability, initial antifouling ability, abrasion resistance, and surface hardness. Examples of the base material having a total ion elution amount of alkali metal ions and alkaline earth metal ions of 1.0 μg / cm ² or more include base materials formed from soda-lime glass, tile, or enamel.

Soda lime glass is also called soda lime glass or soda glass, and is a silicate structure in which sodium ions, calcium ions, etc. are contained in silicate ions in which a tetrahedral structure consisting of silicon atoms and oxygen atoms is connected. It is what has. The glass transition point is, for example, about 730 ° C. and the melting point is about 1000 ° C. The _composition, such as _{SiO 2 -Na 2 O · K 2} O-CaO · MgO-Al 2 O 3 and the like. Specific examples of the composition include SiO ₂ 60 to 75 mol%, Na ₂ O · K ₂ O 10 to ₂₀ mol%, CaO · MgO 5 to 15 mol%, Al ₂ O ₃ 0 to ₅ mol%, and Fe ₂ O ₃ 0.1. %.

  The tile used as a base material in the present invention is a plate-like material obtained by pulverizing soil (clay) or stone (kaolin, feldspar, quartzite, granite, etc.) at a high temperature and applying a glassy glaze. Baked and generally used to cover the interior or exterior of a building. Depending on the quality and water absorption rate of the substrate, it is classified into ceramic tiles, stoneware tiles, and porcelain tiles. Porcelain tiles are generally porous and rough, and have a large water absorption rate (5.0 to 22.5% by weight). The base material is harder than porcelain tiles, and the water absorption rate (1.0-5.0% by weight) is called the stoneware tile. The base material is fine and hard, and the water absorption rate is less than 1.0%. Things are called porcelain tiles.

  The enamel used as a base material in the present invention includes a surface of a metal plate such as iron or aluminum, which is baked by applying a glassy glaze, and is generally used to cover the inside or outside of a building. The thing that is.

  In the present invention, polysilazane or a modified product thereof as a main component in the precoat composition for forming the precoat layer includes those having a main skeleton composed of units represented by the following general formula [I].

(Wherein R ₁ , R ₂ and R ₃ each independently represent a hydrogen atom, an alkyl group, an alkenyl group, a cycloalkyl group or an aryl group, provided that R ₁ , R ₂ and R ₃ At least one of them is a hydrogen atom, and n is preferably an integer in the range of 5 to 500.)

  The method for producing a photocatalyst carrying member of the present invention is a method by which the photocatalyst carrying member of the present invention can be produced. The step of applying a precoat composition on a substrate and then curing it to form a precoat layer And applying a suspension of flaky titanic acid obtained by swelling or peeling the layer by causing a basic compound having an interlayer swelling action to act on the layered titanic acid on the precoat layer, followed by heat treatment and photocatalyst And a step of forming a content layer.

  According to the production method of the present invention, the photocatalyst carrying member of the present invention can be produced efficiently and easily.

  In the manufacturing method of this invention, it is preferable that the heat processing temperature for forming a photocatalyst content layer exists in the range of 400-700 degreeC. If the heat treatment temperature is less than 400 ° C, the flaky titanic acid does not transfer to anatase-type titanium oxide having high photocatalytic performance, so that the photocatalytic performance is low, and if the heat treatment temperature exceeds 700 ° C, the rutile type has low photocatalytic performance. This is because the transition further proceeds to titanium oxide.

  In the present invention, a precoat layer comprising a precoat composition containing polysilazane or a modified product thereof as a main component is formed on a base material, and a basic layer having an interlayer swelling action on layered titanic acid on the precoat layer. A photocatalyst-containing layer made of flaky titanic acid obtained by swelling or peeling between the layers by the action of a compound is formed. Therefore, the precoat layer can prevent alkali metal ions and / or alkaline earth metal ions, particularly sodium ions, eluted from the base material from moving to the photocatalyst containing layer. Therefore, according to the present invention, a photocatalyst carrying member excellent in photocatalytic ability, initial antifouling ability, abrasion resistance, and surface hardness can be obtained.

  Moreover, according to the manufacturing method of the present invention, the photocatalyst carrying member of the present invention can be manufactured efficiently and easily.

  In the present invention, the precoat composition for forming the precoat layer is mainly composed of polysilazane or a modified product thereof as described above. As described above, the polysilazane or a modified product thereof is preferably a polysilazane having a main skeleton composed of units represented by the general formula [I] or a derivative thereof. The number average molecular weight is preferably in the range of 100 to 10,000. Examples of such polysilazane or a modified product thereof include trade names NP-110, NP-120, NN-110, and NN-120 manufactured by AZ Electronic Materials Co., Ltd.

  As described above, the flaky titanic acid used in the present invention can be obtained by swelling or peeling between layers by causing a basic compound having an interlayer swelling action to act on layered titanic acid. Layered titanic acid can be obtained by treating a layered titanate with acid or warm water.

As the layered titanate, for example, potassium carbonate, lithium carbonate, and titanium dioxide are mixed and ground at K / Li / Ti = 3/1 / 6.5 (molar ratio), and fired at 800 ° C. The resulting K _0.8 Li _0.27 Ti _1.73 O ₄ can be mentioned.

Moreover, it is obtained by baking at 700-1200 degreeC the mixture which mixed alkali metal or alkali metal halide, or sulfate as a flux so that the weight ratio of a flux / raw material may be 0.1-2.0. Formula A _x M _y □ Ti _{2- (y + z)} O ₄ (wherein A and M are 1 to 3 valent metals different from each other, □ represents a defect site of Ti. X satisfies 0 <x <1.0. A layered titanate represented by the following formula: y is a positive real number, and y and z are each 0 or a positive real number satisfying 0 <y + z <1.0.

  A in the above formula is a metal having a valence of 1 to 3, and is preferably at least one selected from K, Rb, and Cs. M is a valence 1-3 metal different from the metal A, and is preferably at least one selected from Li, Mg, Zn, Cu, Fe, Al, Ga, Mn, and Ni.

Specific examples include K _0.80 Li _0.27 Ti _1.73 O ₄ , Rb _0.75 Ti _1.75 Li _0.25 O ₄ , Cs _0.70 Li _0.23 Ti _1.77 O. ₄ , Ce _0.70 □ _0.18 Ti _1.83 O ₄ , Ce _0.70 Mg _0.35 Ti _1.65 O ₄ , K _0.8 Mg _0.4 Ti _1.6 O ₄ , K _{0. 8} Ni _0.4 Ti _1.6 O ₄ , K _0.8 Zn _0.4 Ti _1.6 O ₄ , K _0.8 Cu _0.4 Ti _1.6 O ₄ , K _0.8 Fe _0.8 Ti _1.2 O ₄ , K _0.8 Mn _0.8 Ti _1.2 O ₄ , K _0.76 Li _0.22 Mg _0.05 Ti _1.73 O ₄ , K _0.67 Li _0.2 Al _{Examples include 0.07} Ti _1.73 O ₄ .

_Further, after pickling and _{K 0.8 Li 0.27 Ti 1.73 O 4} , obtained by calcining _{K 0.5~0.7} Li _0.27 Ti _1.73 O _3.85~3.95 Is mentioned.

  Examples of the layered titanic acid include those obtained by acid-treating the layered titanate and replacing replaceable metal cations with hydrogen ions or hydronium ions. The acid used for the acid treatment is not particularly limited, and may be a mineral acid such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, boric acid, or an organic acid.

  The suspension of flaky titanic acid is obtained, for example, by causing an organic basic compound having an interlayer swelling action to act on the layered titanic acid in an aqueous medium or an aqueous solution, and swelling or peeling between the layers. Can be mentioned.

  As the organic basic compound having an interlayer swelling action, known compounds can be applied, for example, primary to tertiary amines and salts thereof, alkanolamines and salts thereof, quaternary ammonium salts, phosphonium salts, amino acids and the like. And the like. Examples of the primary amines include methylamine, ethylamine, n-propylamine, butylamine, pentylamine, hexylamine, octylamine, dodecylamine, stearylamine, 2-ethylhexylamine, 3-methoxypropylamine, and 3-ethoxy. Examples thereof include propylamine and salts thereof. Examples of secondary amines include diethylamine, dipentylamine, dioctylamine, dibenzylamine, di (2-ethylhexyl) amine, di (3-ethoxypropyl) amine, and salts thereof. Examples of tertiary amines include triethylamine, trioctylamine, tri (2-ethylhexyl) amine, tri (3-ethoxypropyl) amine, dipolyoxyethylene dodecylamine, and salts thereof. Examples of alkanolamines include ethanolamine, diethanolamine, triethanolamine, isopropanolamine, diisopropanolamine, triisopropanolamine, N, N-dimethylethanolamine, 2-amino-2-methyl-1-propanol, and the like. Of the salt. Examples of the quaternary ammonium hydroxide salts include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide. Examples of quaternary ammonium salts include dodecyl trimethyl ammonium salt, cetyl trimethyl ammonium salt, stearyl trimethyl ammonium salt, benzyl trimethyl ammonium salt, benzyl tributyl ammonium salt, trimethyl phenyl ammonium salt, dimethyl distearyl ammonium salt, dimethyl didecyl ammonium salt. Dimethylstearylbenzylammonium salt, dodecylbis (2-hydroxyethyl) methylammonium salt, trioctylmethylammonium salt, dipolyoxyethylene dodecylmethylammonium and the like.

  Examples of phosphonium salts include organic phosphonium salts such as tetrabutylphosphonium salt, hexadecyltributylphosphonium salt, dodecyltributylphosphonium salt, and dodecyltriphenylphosphonium salt. In addition, amino acids such as 12-aminododecanoic acid and aminocaproic acid and salts thereof, and imines such as polyethyleneimine and salts thereof can also be used.

  These basic compounds may be used singly or as a mixture of several kinds depending on the purpose. In particular, since a basic compound having high hydrophobicity alone does not progress sufficiently, it is preferably used in combination with a basic compound having high hydrophilicity.

  Preferable examples include lower alkyl-substituted organic basic compounds such as 3-methoxypropylamine, n-propylamine, and 2-methyl-2-amino-1-propanol.

  As a method of allowing an organic basic compound having an interlayer swelling action to act, a basic compound or a basic compound is added to an aqueous system under stirring in a suspension in which layered titanic acid after acid treatment or hot water treatment is dispersed in an aqueous medium. The method of adding what was diluted with the medium can be mentioned. Moreover, the method of adding this layered titanic acid or its suspension to the aqueous solution of a basic compound with stirring can be mentioned.

  The aqueous medium or aqueous solution means water, a solvent soluble in water, a mixed solvent of water and a solvent soluble in water, or a solution thereof.

  Examples of the water-soluble solvent include alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol, ketones such as acetone, ethers such as tetrahydrofuran and dioxane, nitriles such as acetonitrile, ethyl acetate, propylene carbonate and the like. And the like.

The addition amount of the basic compound is 0.3 to 10 equivalents, preferably 0.5 to 2 equivalents, of the ion exchange capacity of the layered titanate. Herein, the ion-exchange capacity, a metal cation amount replaceable, for example, when the layered titanate is represented by the general formula _{A x M y □ z Ti 2-} (y + z) O 4, the valence of A Is the value represented by mx + ny, where m is the valence of M and n.

  The reaction is usually carried out at room temperature to 90 ° C. for about 30 minutes to 24 hours.

  As described above, a suspension of flaky titanic acid can be obtained by causing an organic basic compound having an interlayer swelling action to act on layered titanic acid.

  The average major axis of the flaky titanic acid is preferably in the range of 1 to 100 μm, more preferably in the range of 10 to 50 μm. The average thickness is preferably in the range of 0.5 nm to 2 μm, more preferably in the range of 1 nm to 1 μm.

  The average major axis of the flaky titanic acid is a step in which delamination is performed by applying a basic compound, and the average major axis of the layered titanate as a raw material can be substantially maintained unless stirring is performed with a strong shearing force. .

  When the average major axis of the flaky titanic acid is less than 1 μm, it may be difficult to form a uniform coating film. In addition, flaky titanic acid having an average major axis exceeding 100 μm is difficult to synthesize raw material layered titanate having an average major axis exceeding 100 μm.

  Since the average thickness of the flaky titanic acid is about 0.5 nm when the layered titanic acid is peeled up to a single layer, it is difficult to make the average thickness less than 0.5 nm. On the other hand, when the average thickness exceeds 2 μm, the flaky titanic acid suspension becomes difficult to uniformly disperse, and the flaky titanic acid may settle.

  A photocatalyst-containing layer can be formed by applying flaky titanic acid, for example, as a suspension and heat-treating it. The concentration of the flaky titanic acid suspension is preferably in the range of 0.01 to 50% by weight, more preferably in the range of 0.1 to 10% by weight, as the solid content concentration. When the solid content concentration is less than 0.01% by weight, it may be difficult to form a coating film because the viscosity is low, and when it exceeds 50% by weight, the viscosity becomes high and handling may be difficult.

  According to the production method of the present invention, after a precoat composition is applied on a substrate, it is cured to form a precoat layer, and a flaky titanic acid suspension is applied on the precoat layer. And heat treatment to form a photocatalyst-containing layer.

  The precoat composition can be applied by a method such as spray coating, dip coating, spin coating, flow coating, or roll coating. After applying the precoat composition, it is cured by heating. This hardening process can be hardened by heating for 1 minute to 1 hour at the temperature of 25-250 degreeC, for example.

  The film thickness of the precoat layer is preferably in the range of 40 nm to 1000 nm, more preferably in the range of 50 nm to 200 nm. When the film thickness of the precoat layer is 40 nm or less, the effect of suppressing the migration of alkali metal ions and / or alkaline earth metal ions, particularly sodium ions, eluted from the substrate to the photocatalyst containing layer is sufficiently obtained. There may not be. Moreover, even if the film thickness of the precoat layer is 1000 nm or more, the effect is not changed, and a film thickness of more than that is uneconomical.

  The flaky titanic acid suspension may be an aqueous suspension of flaky titanic acid obtained by swelling or peeling between layers by causing a basic compound having an interlayer swelling action to act on layered titanic acid. Alternatively, this aqueous suspension may be dispersed in a hydrophilic alcohol and used as a hydrous alcohol suspension. For example, ethanol is preferable as the hydrophilic alcohol.

  The flaky titanic acid dispersion prepared as described above is applied on the precoat layer and then heat-treated to form a photocatalyst-containing layer. As described above, the heat treatment temperature is preferably in the range of 400 to 700 ° C. The heat treatment time is, for example, 10 minutes to 1 hour.

  The thickness of the photocatalyst-containing layer is not particularly limited, but is generally in the range of 4 nm to 50 nm, preferably in the range of 10 nm to 20 nm. If the thickness of the photocatalyst-containing layer is too thin, the photocatalytic ability may not be sufficiently obtained. Even if the photocatalyst-containing layer is too thick, the effect is not changed, which is uneconomical.

  If necessary, a binder may be added to the flaky titanic acid suspension. Examples of the binder include silica-based binders such as tetraethoxysilane, alumina-based binders such as aluminum isopropoxide, and titania-based binders such as titanium tetraisopropoxide. These binders can be added so that it may become 0.01 to 0.1 weight% with respect to the suspension of flaky titanic acid, for example.

  By adding a binder, the abrasion resistance of the photocatalyst-containing layer can be improved, and the adhesion to the precoat layer can also be improved.

  According to the present invention, it is possible to obtain a photocatalyst carrying member that is excellent in surface hardness and wear resistance and in which initial adhesion of contaminants is reduced. The photocatalyst carrying member of the present invention can be used for, for example, general household window glass, window glass for trains, buses, automobiles, etc., glass for lighting fixtures, cover glass for solar cells, and the like. Furthermore, the present invention can also be applied to those coated with a soda-lime glass glaze such as tiles and enamels.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples, and can be appropriately changed without departing from the scope of the present invention.

<Synthesis of flaky titanic acid suspension>
(Synthesis Example 1)
A raw material in which 27.64 g of potassium carbonate, 4.91 g of lithium carbonate, and 69.23 g of titanium dioxide were pulverized and mixed by a dry method was calcined at 1060 ° C. for 4 hours. The fired sample was immersed in 10 kg of deionized water, stirred for 20 hours, separated, washed and dried at 110 ° C. The obtained white powder was layered titanate K _0.80 Li _0.27 Ti _1.73 O ₄ and had an average major axis of 32 μm.

65 g of this layered titanate was dispersed and stirred in 5 kg of 3.5% hydrochloric acid, reacted at 40 ° C. for 2 hours, separated by suction filtration, and washed with water. The obtained layered titanic acid had a K ₂ O residual amount of 0.2% and a metal ion exchange rate of 99.6%. The total amount of the layered titanic acid obtained was dispersed in 1.6 kg of deionized water, and a solution prepared by dissolving 15.1 g (1 equivalent) of 3-methoxy-propylamine in 0.4 kg of deionized water was added with stirring. After stirring at ° C for 12 hours, micromesh filtration was performed to obtain a flaky titanic acid suspension. The obtained suspension had a pH of 11.0 and a concentration of 2.7% by weight, and no sedimentation of solid matter was observed even after standing for a while. This was designated as flaky titanic acid suspension A. The average major axis of the flaky titanic acid was 31 μm and the average thickness was 1 nm.

(Synthesis Example 2)
A flaky titanic acid suspension B was prepared in the same manner as in Synthesis Example 1, except that the basic compound was replaced with n-propylamine. The obtained flaky titanic acid suspension B had a pH of 11.5 and a concentration of 2.9% by weight, and no solid sedimentation was observed even after standing for a while. The average major axis was 31 μm and the average thickness was 1 nm.

(Synthesis Example 3)
A flaky titanic acid suspension C was prepared in the same manner as in Synthesis Example 1 except that the basic compound was replaced with 2-methyl-2-amino-1-propanol. The obtained flaky titanic acid suspension C had a pH of 10.6 and a concentration of 3.1% by weight, and no solid sedimentation was observed even after standing for a while. The average major axis was 31 μm and the average thickness was 1 nm.

(Synthesis Example 4)
18.5 g of flaky titanic acid suspension A of Synthesis Example 1 was diluted with 31.5 g of deionized water, 150 g of ethanol and 0.05 g of titanium isopropoxide were further added, and 0.25 wt% of flaky titanic acid was added. Ethanol suspension D was obtained.

<Manufacture of photocatalyst carrying member>
As a base material for the photocatalyst support member, a soda-lime glass plate, a general interior tile, and a general interior enamel plate were used. The tiles are pottery tiles whose surfaces are treated with glassy glaze. The enamel plate is baked by applying a glassy glaze on an iron plate (steel plate). About each base material, the ion elution amount (total ion elution amount) of sodium ion, lithium ion, potassium ion, beryllium ion, magnesium ion, and calcium ion was measured. The total ion elution amount was obtained by immersing three substrates (6 cm (length) x 6 cm (width) x 2 mm (thickness)) in 250 g of distilled water at 80 ° C. for 24 hours, and analyzing the amount of each ion in distilled water by atomic absorption spectrometry. It was determined by measuring with. The total ion elution amount of each substrate is as follows.

Soda lime glass plate: 2.90 μg / cm ²
General interior tile: 12.3 μg / cm ²
General interior enamel plate: 15.6 μg / cm ²

Example 1
Polysilazane (manufactured by AZ Electronic Materials Co., Ltd., trade name NP-110, 20% by weight xylene solution) was diluted to 2% by weight with a butyl acetate solvent, and 6 cm (length) × 6 cm (width) × 2 mm (thickness) The soda-lime glass plate was applied by spin coating, and dried at 25 ° C. for 1 hour to form a precoat layer (film thickness 50 nm).

  On this precoat layer, the flaky titanic acid suspension A produced in Synthesis Example 1 was applied by spin coating, and after application, baked at 500 ° C. for 10 minutes to form a photocatalyst-containing layer (film thickness 10 nm). Thus, a light carrying member was obtained.

(Example 2)
Polysilazane (manufactured by AZ Electronic Materials Co., Ltd., trade name NN-110, 20% by weight xylene solution) was diluted to 2% by weight with a butyl acetate solvent, and 6 cm (length) × 6 cm (width) × 2 mm (thickness) The soda-lime glass plate was applied by spin coating, and dried at 25 ° C. for 1 hour to form a precoat layer (film thickness 50 nm).

  On this precoat layer, the flaky titanic acid suspension B produced in Synthesis Example 2 was applied by spin coating, and after application, baked at 500 ° C. for 10 minutes to form a photocatalyst containing layer (film thickness 10 nm). Thus, a light carrying member was obtained.

(Comparative Example 1)
In place of the flaky titanic acid suspension A, titanium oxide ethanol diluted to 2% by weight with particulate titanium oxide (manufactured by Nippon Soda Co., Ltd., trade name “Vistreator L NRC-360C”) with ethanol A photocatalyst carrying member was obtained in the same manner as in Example 1 except that the suspension was used. The film thickness of the photocatalyst containing layer was 10 nm.

(Comparative Example 2)
In place of polysilazane, alkoxysilane (manufactured by Nippon Soda Co., Ltd., trade name “Vistreiter H NDH-500A”) diluted to 2% by weight with ethanol was used and replaced with flaky titanic acid suspension. Thus, a photocatalyst carrying member was obtained in the same manner as in Example 1 except that the same ethanol suspension of titanium oxide as in Comparative Example 1 was used. The film thickness of the photocatalyst containing layer was 10 nm.

(Comparative Example 3)
A photocatalyst carrying member was obtained in the same manner as in Example 1 except that the same alkoxysilane as in Comparative Example 2 was used and the same flaky titanic acid suspension A as in Example 1 was used.

[Evaluation of photocatalyst carrying member]
About the photocatalyst carrying member produced in Examples 1-2 and Comparative Examples 1-3, a contact angle, a decomposition rate, initial stage adhesion, abrasion resistance, and surface hardness were measured. The contact angle is for evaluating super hydrophilicity, and the decomposition rate is for evaluating optical resolution. The initial adhesion is for evaluating the initial antifouling ability, and the wear resistance is for evaluating the adhesion. These were evaluated as follows.

(1) Contact angle After irradiating black light (1 mW / cm < ² >) on the surface in which the photocatalyst containing layer of the photocatalyst carrying member was formed for 12 hours, pure water was dropped and the contact angle was measured.

(2) Decomposition rate After measuring the initial adhesion described below, before irradiation with black light by irradiating black light (1 mW / cm ² ) for 3 hours and measuring the amount of methylene blue (MB) after irradiation. The decomposition rate was calculated from the MB amount after irradiation.

(3) Initial adhesion The photocatalyst-supporting member is immersed in a 0.1 mM methylene blue (MB) aqueous solution overnight, then taken out, washed with deionized water, and then the area of the absorption spectrum of MB with a visible ultraviolet spectrophotometer. Was measured.

(4) Abrasion resistance In accordance with JIS (Japanese Industrial Standards) K5400, a grid is formed on the surface of the photocatalyst containing layer, and a tape is attached to the surface to peel off. Indicated.

(5) Surface hardness Pencil hardness was measured according to JIS K5400.

  The measurement results are shown in Table 1.

  As shown in Table 1, in Comparative Example 1 using particulate titanium oxide instead of flaky titanic acid, the photocatalytic ability (contact angle and decomposition rate) is lower than in Examples 1 and 2. It can be seen that the initial antifouling ability (initial adhesion), wear resistance (adhesion) and surface hardness are also reduced.

  In Comparative Example 2, alkoxysilane was used instead of polysilazane, and particulate titanium oxide was used instead of flaky titanic acid. In Comparative Example 3, alkoxysilane was used instead of polysilazane, and the photocatalyst-containing layer was formed using flaky titanic acid. In Comparative Example 2 and Comparative Example 3, all of photocatalytic ability (contact angle and decomposition rate), initial antifouling ability (initial adhesion), abrasion resistance (adhesion), and surface hardness are considerably worse than those in Examples 1 and 2. It has become. Compared with Comparative Example 2 and Comparative Example 3, the results are almost the same. When Examples 1 and 2 are compared with Comparative Example 1, the flakes according to the present invention are used instead of the particulate titanium oxide of Comparative Example 1. It can be seen that by using the titanic acid, the photocatalytic ability (contact angle and decomposition rate), initial antifouling ability (initial adhesion), abrasion resistance (adhesion), and surface hardness are remarkably improved. Therefore, it can be seen that by using a precoat layer made of polysilazane, performance such as photocatalytic activity of flaky titanic acid can be exhibited better. This is because the influence of alkali metal ions and / or alkaline earth metal ions, particularly sodium ions, eluted from the base material can be effectively reduced by providing a precoat layer made of polysilazane on the base material. I think that the.

(Example 3)
The same polysilazane as used in Example 1 was diluted to 2% by weight with a butyl acetate solvent, and spin coated on a general interior tile having a size of 14 cm (length) × 14 cm (width) × 4 mm (thickness). It was coated by the method and dried at 25 ° C. for 1 hour to form a precoat layer (film thickness 100 nm). Next, the flaky titanic acid suspension C produced in Synthesis Example 3 was applied onto this precoat layer by a spin coating method, and then baked at 500 ° C. for 10 minutes to thereby form a photocatalyst-containing layer (film thickness: 10 nm). ) To obtain a photocatalyst carrying member.

Example 4
The polysilazane used in Example 2 was diluted to 2% by weight with a butyl acetate solvent, and applied to a general interior enamel plate of 6 cm (length) × 6 cm (width) × 1 mm (thickness) by dip coating. Thereafter, the film was dried at 200 ° C. for 10 minutes to form a precoat layer (film thickness 100 nm). The flaky titanic acid ethanol suspension D produced in Synthesis Example 4 was applied onto this precoat layer by a dip coating method, and then baked at 500 ° C. for 10 minutes to form a photocatalyst-containing layer (film thickness 10 nm). The photocatalyst carrying member was obtained.

(Comparative Example 4)
It replaces with flaky titanic acid suspension C, and is the same as Example 3 except forming a photocatalyst content layer (film thickness of 10 nm) using the same titanium oxide ethanol dispersion liquid used in comparative example 1. Thus, a photocatalyst carrying member was obtained.

(Comparative Example 5)
A precoat layer (film thickness 100 nm) is formed using the same alkoxysilane as used in Comparative Example 2, and the flaky titanic acid suspension B is used instead of the flaky titanic acid suspension C. A photocatalyst carrying member was obtained in the same manner as in Example 3.

[Evaluation of photocatalyst carrying member]
Similarly to the above, for the photocatalyst carrying members of Examples 3 to 4 and Comparative Examples 4 to 5, photocatalytic ability (contact angle and decomposition rate), initial antifouling ability (initial adhesion), wear resistance (adhesion), The surface hardness was measured, and the measurement results are shown in Table 2.

  As shown in Table 2, Examples 3 and 4 in which a precoat layer was formed from polysilazane according to the present invention, and a photocatalyst-containing layer was formed using flaky titanic acid, compared with Comparative Examples 4 and 5, It turns out that it is excellent in antifouling ability, abrasion resistance, and surface hardness.

Claims (5)

By immersing three 6 cm × 6 cm × 2 mm sample plates in 250 g of distilled water at 80 ° C. for 24 hours, and measuring the amount of alkali metal ions and alkaline earth metal ions in the distilled water by atomic absorption spectrometry A substrate having a total ion elution amount required of 1.0 μg / cm ² or more;
A precoat composition comprising polysilazane or a modified product thereof as a main component, applied onto the substrate and cured,
A photocatalyst formed by applying flaky titanic acid obtained by swelling or peeling between layers by causing a basic compound having an interlayer swelling action to act on layered titanic acid, and then applying heat treatment to the precoat layer. A photocatalyst carrying member comprising a containing layer.   The photocatalyst carrying member according to claim 1, wherein the base material is formed of soda-lime glass, tile, or enamel. 3. The photocatalyst-supporting member according to claim 1, wherein the polysilazane or a modified product thereof has a main skeleton composed of units represented by the following general formula [I].

(Wherein R ₁ , R ₂ and R ₃ each independently represent a hydrogen atom, an alkyl group, an alkenyl group, a cycloalkyl group or an aryl group, provided that R ₁ , R ₂ and R ₃ At least one of them is a hydrogen atom.) A method for producing the photocatalyst carrying member according to any one of claims 1 to 3,
A step of applying the precoat composition on the substrate and then curing to form the precoat layer;
And a step of applying the flaky titanic acid suspension on the precoat layer and then heat-treating it to form the photocatalyst-containing layer.   The method for producing a photocatalyst-supporting member according to claim 4, wherein the heat treatment temperature is in the range of 400 to 700 ° C.