WO2001017680A1

WO2001017680A1 - Particulate titanium dioxide photocatalyst, process for producing the same, and applications thereof

Info

Publication number: WO2001017680A1
Application number: PCT/JP2000/006152
Authority: WO
Inventors: Hiroyuki Hagihara; Katsura Ito
Original assignee: Showa Denko Kabushiki Kaisha
Priority date: 1999-09-08
Filing date: 2000-09-08
Publication date: 2001-03-15
Also published as: AU6876400A

Abstract

A particulate titanium dioxide photocatalyst which comprises: fine titanium dioxide particles; a first deposit layer comprising a calcium compound and formed on the surface of the particles; and a second deposit layer which is a porous layer formed on the surface of the fine titanium dioxide particles having the first deposit layer and comprises an insoluble substance which is photocatalytically inactive and has a solubility product in water of 10-25 or smaller. A composition comprising this particulate titanium dioxide photocatalyst and an organic polymer is used as a molding material, coating material, or the like for producing a molding or structure for environmental purification.

Description

Titanium dioxide photocatalyst powder, its production method, and its application

The present invention relates to a photocatalyst powder containing titanium dioxide as a photocatalyst, a method for producing the photocatalyst powder, a polymer composition containing the photocatalyst powder, a molded product of the polymer composition, and the photocatalyst powder or the powder. The present invention relates to a structure having a combined composition on the surface.

The titanium dioxide photocatalyst powder of the present invention is used as an environmental purification material for removing odors, decomposing and removing harmful substances or dirt in the air, wastewater treatment and purification treatment, or sterilization and algicidal treatment of water. In particular, it is applied to the surface of textiles, paper and plastic moldings, or kneaded with fiber or plastic media during the production process of textiles and plastic moldings, or used as an environmental purification material in the form of paints. Suitable for. Background art

In recent years, photocatalysts using titanium dioxide fine particles have attracted attention as environmental purification materials used for antibacterial, deodorant, antifouling, air purification, and water purification purposes. The photocatalytic mechanism of titanium dioxide is such that when light is applied to the titanium dioxide fine particles, electrons and holes generated inside the titanium dioxide fine particles convert water and oxygen near the surface of the titanium dioxide fine particles into hydroxyl radicals and hydrogen peroxide. It is considered to convert harmful substances into harmless substances such as carbon dioxide by the strong redox effect of hydroxyradical and hydrogen peroxide. It is said that the photocatalytic action of titanium dioxide particles lasts semi-permanently as long as titanium dioxide particles, light, water, and oxygen are present.

In the application of such a titanium dioxide photocatalyst, attempts have been made to knead fiber or plastic media in the process of manufacturing easily-manufactured fiber-plastic molded articles, or apply them to the surface of a substrate such as cloth or paper. Have been. However, due to the strong photocatalytic action of titanium dioxide, not only harmful organic substances and environmental pollutants, but also media such as fibers, plastics, and paper themselves are easily decomposed and deteriorated, which hinders practical use. It was harmful. Furthermore, paints in which titanium dioxide fine particles and a binder are mixed have attracted attention due to their ease of handling, but no inexpensive binder has been found that overcomes such obstacles to the medium.

Japanese Patent Application No. 9-22539 / 1992 and Japanese Patent Application Laid-Open No. 9-239277 disclose the use of dioxidation in order to suppress the deterioration of the resin medium and binder due to the action of titanium dioxide particles. A method has been proposed in which a photoinactive compound is supported in the form of islands distributed on the surface of titanium particles to suppress the photocatalytic action. According to this method, the deterioration of the resin medium and the binder is reduced, but the activity as a photocatalyst is reduced because the photoinactive compound directly adheres to the active point on the surface of the titanium dioxide particles. Is required. In addition, Japanese Patent Application Laid-Open No. H10-244416 proposes a photocatalyst in which titanium dioxide particles are coated with porous calcium phosphate on the surface. The photocatalytic performance of these coated titanium dioxide particles is reduced by the calcium phosphate coating layer, and there is still a problem in durability under strong ultraviolet rays such as sunlight.

Disclosure of the invention

An object of the present invention is to improve the environment in view of the above-mentioned conventional technologies, such as removing odors, decomposing and removing harmful substances or dirt in the air, treating wastewater and purifying water, and imparting antibacterial and antifungal properties. It can be performed effectively, economically and safely, especially when applied to fibers, paper, plastic moldings, etc., or when mixed with fibers or plastic moldings, or when used in the form of paint, etc. A photocatalyst powder having good long-term durability without causing deterioration of a medium, a method for producing the photocatalyst powder, a polymer composition containing the photocatalyst powder, a molded article of the polymer composition, and An object of the present invention is to provide a structure having the polymer composition on the surface.

In particular, a main object of the present invention is to provide a photocatalyst powder exhibiting excellent durability under a strong light irradiation environment such as sunlight, a polymer composition containing the photocatalyst powder, and a molding of the polymer composition. And a structure having the polymer composition on the surface. The present inventor has conducted intensive studies to achieve the above object, and has found that titanium dioxide A first support layer for supporting a calcium compound is formed on the surface of the fine particles, and a porous second support layer for supporting, on the surface of the titanium dioxide fine particles, a water-insoluble substance inert as a photocatalyst. It has been found that the formation of is a photocatalyst with excellent durability without hardly impairing the high photocatalytic action of the titanium dioxide fine particles and without deteriorating the medium.

Thus, according to the present invention, a titanium oxide fine particle has a first support layer containing a calcium compound on the surface thereof, and the first support layer is formed on the surface of the titanium dioxide fine particle as a photocatalyst. There is provided a titanium dioxide photocatalyst powder characterized by having a porous second support layer that is inert and contains a substance that is hardly soluble in water. The poorly soluble substance preferably has a solubility product in water of 10 to ²⁵ or less.

Further, according to the present invention, a method for producing a titanium dioxide photocatalyst powder having the above-described first support layer and second support layer,

(1) A calcium compound is supported on the surface of the titanium dioxide fine particles to form a first support layer, and the surface of the titanium dioxide fine particles on which the first support layer is formed is hardly inactive as a photocatalyst. Supporting a material capable of forming a soluble substance, followed by drying or baking to convert the material to the poorly soluble substance and forming a porous second supporting layer containing the poorly soluble substance; A method for producing a titanium dioxide photocatalyst powder, comprising:

(2) A calcium compound is supported on the surface of the titanium dioxide fine particles to form a first support layer, and the surface of the titanium dioxide fine particles on which the first support layer is formed is further coated with an alkali aqueous solution containing metal ions. Then, the aqueous solution is neutralized, and the surface of the titanium dioxide fine particles on which the first support layer has been formed is contacted with a porous second support containing an insoluble hardly-soluble substance as a photocatalyst. A method for producing a titanium dioxide photocatalyst powder characterized by forming a layer; and

(3) A calcium compound is supported on the surface of the titanium dioxide fine particles to form a first supporting layer, and further, a metal alkoxide is hydrolyzed on the surface of the titanium dioxide fine particles on which the first supporting layer is formed. A photocatalyst on the surface of the titanium dioxide particles. Forming a porous second supporting layer containing an inert hardly soluble substance, thereby providing a method for producing a titanium dioxide photocatalyst powder.

Further, according to the present invention, a polymer composition comprising an organic polymer as a medium and the above titanium dioxide photocatalyst powder; a polymer molded article obtained by molding the polymer composition; and a photocatalyst powder A body or a structure having the polymer composition on a surface is provided. BEST MODE FOR CARRYING OUT THE INVENTION

The titanium dioxide fine particles used in the present invention are not particularly limited as long as they have a photocatalytic action.However, those having a crystal form mainly composed of ana-yuzuze zebrockite are preferable because of their high photocatalytic ability. . The average particle diameter of the primary particles of the titanium dioxide fine particles is preferably from 0.01 to 0.2 micron, particularly preferably from 0.01 to 0.1 micron. If the average particle size of the primary particles is less than 0.001 micron, it is difficult to produce efficiently and it is not practical. If it exceeds 0.2 micron, the performance as a photocatalyst is greatly reduced.

The production method of the titanium dioxide fine particles used in the present invention is not particularly limited as long as they basically have a photocatalytic activity.For example, those prepared by a gas phase reaction using titanium halide as a raw material, or Either a titanium halide solution or titanyl sulfate hydrolyzed by a wet method or a calcined product thereof may be used.

As the calcium compound carried on the surface of the titanium dioxide fine particles, a compound which is hardly soluble in water is used so as not to be easily eluted. There is no particular limitation as long as it is sparingly soluble in water. For example, calcium oxides, phosphates, sulfates, nitrates, carbonates, and salts with organic acids are applicable. Particularly, calcium phosphate, organic carboxylic acid calcium salt and oxidizing calcium are preferable.

As a method of supporting a calcium compound on the surface of titanium dioxide fine particles, generally, titanium dioxide fine particles are dispersed in a solution of a soluble calcium salt (for example, an aqueous solution of calcium chloride), and the calcium compound is added by adding a precipitation agent. Titanium Precipitate on the surface of fine particles (for example, adding calcium phosphate by adding Na ₂ HP (L etc.) Method). If desired, this operation can be repeated to form two or more calcium compound coating layers.

The form of the first supporting layer containing the calcium compound is not particularly limited as long as the photocatalytic function of the titanium dioxide fine particles is maintained. For example, a porous calcium compound is dispersed and supported on the surface of titanium dioxide fine particles in the form of islands, or a porous calcium compound is supported on the entire surface of titanium dioxide fine particles. You may.

The weight of the first support layer containing the calcium compound is preferably from 0.01 to 10% by weight, more preferably from 0.1 to 5% by weight, based on the weight of titanium dioxide. If the amount is less than 0.01% by weight, the durability as a photocatalyst deteriorates when added to plastics and the like, while if it is more than 10% by weight, the photocatalytic function deteriorates.

The titanium dioxide photocatalyst powder of the present invention comprises, on the surface of the titanium dioxide fine particles on which the first support layer containing a calcium compound is formed, a porous second water-insoluble substance which is inactive as a photocatalyst. Is formed. By forming such a second support layer, a photocatalyst with much higher durability can be obtained without substantially impairing the high catalytic action of the titanium dioxide fine particles and without causing deterioration of the medium.

The substance supported as the second supporting layer is a substance that does not substantially exhibit a catalytic action by light and is hardly soluble in porous water. As for the solubility of this substance in water, it is particularly preferable that its solubility product at 25 ° C (also referred to as solubility constant) is 10 to ²⁵ or less. Here, the “porous second support layer” means that the second support layer is made of a solid substance having a large number of pores, and the size of the pores and the thickness of the support layer are: without inhibiting the movement of the gas or organic low molecular substances such as NO _x, and is of a degree that allows the light transparently.

The second support layer may not only exist on the outer surface of the first support layer but may have a portion supported on the exposed surface of the titanium dioxide fine particles where the first support layer does not exist.

Examples of the poorly water-soluble substance supported as the second support layer include, for example, Be, B, M g, Al, Si, V, Cr, Mn, Fe, Co, Cu, Zn, Ge, Zr, Ag, In, Sn, Pb, Sb, Ba, Ta, Ce Hardly water-soluble substances containing at least one element. Specific examples of poorly water-soluble material is a metal oxide B E_〇, B ₂ 〇 _{_{3, MgO, A 1 2 0}} 3, S i OS i 0, V 2 〇 _{5, C rO, C r 20} 3, MnO, Mn ₂ 0 _3, Mn_〇 _{_{_{2, Mn 3 0 4, Fe}}} 2 〇 _{_{_{3, F e 3 0 4 CoO}}} , Co 3 〇 _4, Cu ₂ _{〇, CuO, ZnO, Ge0 2,} Z R_〇 _2, Ag ₂ _{〇, I nO, I n 2 0} 3, Sn_〇, Sn_〇 _2, Pb ₃ 0 _4, Pb_〇 _2, PbO, S B_〇 _{_{_{2, S b 2 0 3,}}} S b 2 0 5, B aT i 0 _3, Ta_〇 _2, Ta ₂ 〇 _{_{5, C e 0 2, C}} a T i 0 3, F e T i 0 3 can be cited, and in non-metallic oxide, CuS, Cu (〇 H) _2, AgC and AgB r, Ag l, AgS, Mg ( _{_{_{〇_H) 2, MgC0 3, CaC0 3}}} , B AC_〇 _{_{3, Zn (OH) 2,}} ZnS, ZnC0 3, CdS, A 1 ( 〇 H _{_{) 3, Sn (OH) 2}} , SnS, SnS 2, PbS, PbC l 2, PbS0 3, P b C_〇 _{_{_{3, Sb 2 S 3, F}}} e S and the like. Among the hardly water-soluble substances described above, silica, alumina, zirconia, aluminum hydroxide, titanium hydroxide, and aluminum phosphate are preferred, and among these, silica, alumina and zirconia are particularly preferred.

The method of forming the porous second support layer includes a method of directly supporting the poorly water-soluble substance on the surface of the titanium dioxide fine particles having the first support layer containing a calcium compound, and a method of forming the porous second support layer. Any of the methods of contacting or supporting a precursor of a soluble substance and converting the precursor into the above-mentioned poorly water-soluble substance can be adopted. Representative examples of the method of forming the second support layer include the following three methods.

(1) A material capable of forming a sparingly water-soluble substance which is substantially inactive as a photocatalyst on the surface of titanium dioxide fine particles having the above-mentioned first supporting layer containing a calcium compound, for example, a silicone oligomer or A method of attaching a silane coupling material, drying and drying or baking to convert the material into the hardly water-soluble substance, and form a second support layer containing the hardly water-soluble substance.

Preferred examples of the material capable of forming a substantially water-insoluble substance which is substantially inactive as a photocatalyst include a silicone oligomer or a silane coupling material. I can do it. By depositing these materials, drying and / or calcining, the materials are converted to silica, forming a second support layer containing porous silica.

(2) The surface of the titanium dioxide fine particles having the first support layer containing the above-mentioned calcium compound is brought into contact with an aqueous alkali solution containing metal ions, and then the aqueous solution is neutralized to thereby be substantially inert as a photocatalyst. Forming a porous second support layer containing a poorly water-soluble substance.

Specific examples of the aqueous alkali solution containing metal ions used in this method include aqueous solutions of sodium aluminate, sodium silicate and sodium zirconate. For example, the titanium dioxide fine particles having the first support layer are brought into contact with an aqueous solution of sodium aluminate, and then the aqueous solution is neutralized by adding an inorganic acid, and porous alumina is deposited to deposit porous alumina. A carrier layer is formed.

(3) Hydrolysis of metal alkoxide on the surface of titanium dioxide fine particles having a first supporting layer containing a calcium compound to convert the metal alkoxide to metal oxide or the like, which is substantially inactive as a photocatalyst. A porous second support layer for supporting a soluble substance is formed.

Specific examples of the metal alkoxide used in this method include zirconium n-butoxide, aluminum triethoxide, aluminum triisopropoxide, methyl silicate, ethyl silicate, silicon ethoxide, and zirconium isopropoxide. Can be For example, titanium dioxide fine particles having a first carrier layer are brought into contact with an alcohol slurry of zirconium n-butoxide, and ethylene glycol and water are added to the slurry and hydrolyzed to deposit porous zirconia. A quality second carrier layer is formed.

If desired, the method for forming the second support layer as described above can be repeated to form a porous second support layer having two or more layers.

The weight of the porous second carrier layer is preferably from 0.01 to 50% by weight, more preferably from 0.1 to 20% by weight, based on the weight of titanium dioxide. If less than 0.01% by weight is added to plastics as a medium, the durability as a photocatalyst Worse. On the other hand, if the content is more than 50% by weight, the photocatalytic function is reduced, and the cost is increased.

The titanium dioxide photocatalyst powder having an environmental purification function of the present invention has at least one metal selected from the group consisting of platinum, rhodium, ruthenium, palladium, silver, copper, zinc, and the like supported on the surface thereof. You may. When such metals are supported, the rate of oxidative decomposition of chemical substances by photocatalysis by titanium dioxide is further increased, and sterilization and algicidal actions are also increased. These metals are supported on the surface of the raw titanium dioxide fine particles, on the surface or layer of the first supporting layer containing a calcium compound, or on the surface or layer of the porous second supporting layer containing a poorly water-soluble substance. Any may be done. The loading of these metals may be carried out by a conventional method, and the loading amount is usually selected in the range of 0.001 to 10% by weight based on the weight of the titanium dioxide photocatalyst powder.

The titanium dioxide photocatalyst powder of the present invention can be used as a medium as a polymer composition by being added to all kinds of organic polymers. As the organic polymer, thermoplastic synthetic resins, thermosetting synthetic resins, natural resins, and the like are widely used, and the types thereof are not particularly limited. Since the titanium dioxide photocatalyst powder of the present invention has the first support layer and the second support layer on the surface, when added to the organic polymer, the organic polymer directly contacts the surface of the titanium dioxide fine particles. The decomposition of the organic polymer does not occur due to the photocatalytic activity of the titanium dioxide fine particles.

Specific examples of the organic polymer used as a medium include polyethylene, polyamide, polyvinyl chloride, polyvinylidene chloride, polyester (polyethylene terephthalate, aramide, thermosetting unsaturated polyester, etc.), polypropylene, and polyethylene oxide. , Polyethylene glycol, silicone resin, polyvinyl alcohol, vinyl acetal resin, ABS resin, epoxy resin, vinyl acetate resin, cellulose, cellulose derivatives, regenerated cellulose (rayon, etc.), polyurethane, polycarbonate, polystyrene, urea resin, fluorine resin (polyfluorinated) Vinylidene, polytetrafluoroethylene, etc.), phenolic resin, celluloid, chitin, starch, acrylic resin, melamine resin, alkyd resin, etc. . The polymer composition comprising the organic polymer and the titanium dioxide photocatalyst powder of the present invention can be used as a material for environmental purification in the form of a paint, a coating composition, a compound, a masterbatch, and the like. The concentration of the titanium dioxide photocatalyst powder in the organic polymer composition is usually 0.01 to 80% by weight, preferably 1 to 50% by weight, based on the total weight of the composition.

Into the polymer composition, an absorbent such as activated carbon for absorbing malodorous substances and harmful substances, or a zealite light may be added.

Furthermore, a molded article having an environmental purification function can be obtained by molding the above polymer composition. Examples of molded articles of such a polymer composition include extruded articles such as fibers, films and sheets, and various injection molded articles and compression molded articles.

Further, since the polymer composition of the present invention has excellent durability, it can be applied as a coating composition to structures such as walls, glass, signboards, and concrete. Further, the polymer composition of the present invention can be applied to an organic structure such as paper, plastic molded article, cloth and wood product, or a structure having a coating film such as a vehicle, The photocatalyst function can be fully exhibited without destroying the coating film.

Hereinafter, the present invention will be described specifically with reference to examples. However, the present invention is not limited at all by the following examples. In the following Examples and Comparative Examples,% is based on weight unless otherwise specified.

Example 1

120 g of ultrafine titanium dioxide particles (F-4, manufactured by Showa Yu Itanim Co., Ltd., average particle size of primary particles: 0.03 micron) were put into 2.8 L of pure water and dispersed to obtain a titanium dioxide slurry. . Then, pure water To NaC by adding Na _₂ HP0 _4, KH ₂ P_〇 _{4, KC 1, MgC 12 ·} 6H 2 0, CaC 1 2, the N a + after mixing with titanium dioxide Nsurari 139 mm, K + is 2.8 mM, 3 ^{2 +} is ^{1. 8mM, Mg 2 ^ S0.5mM,} CI force 144 mM, HP 0 ₄ ² - and H ₂ P_〇 ₄ - salt total concentration was adjusted to be 1. ImM of A 3.5 L solution was prepared. The method 2.8 L of the titanium dioxide slurry obtained above and 3.5 L of the salt solution were mixed, and further kept at a temperature of 40 ° C for 24 hours. Thereafter, the slurry was filtered and washed (using an adept technical membrane filter, pore size 0.2 im, used) and dried at 120 ° C for 4 hours to obtain 100 g of fine powder of titanium dioxide having calcium phosphate supported on the surface. The obtained fine powder of titanium dioxide having a calcium phosphate-supporting layer on the surface was mixed with a blender (Warling), and 20% of a silicone oligomer (AFP-1 manufactured by Shin-Etsu Chemical Co., Ltd.) was sprayed thereon. The obtained mixed powder was dried in the air at 120 for 2 hours, and then fired at 500 ° C for 10 hours. As a result of chemical analysis, the obtained powder was found to carry 1% of calcium phosphate and 10% of porous silica. Next, 3.5 g of the obtained fine powder of titanium dioxide having a porous silica-supporting layer was placed in a 9 Ommci) petri dish, and then placed in a 5 L Tedlar bag containing acetoaldehyde having an initial concentration of 40 ppm. Irradiation was performed with black light at 365 nm of ultraviolet light so as to have an intensity of 0.23 mWZcm ² . One hour after the start of ultraviolet irradiation, the concentration of acetoaldehyde was measured with a detector tube, and the residual ratio of acetoaldehyde was 5%.

Next, a urethane resin for fiber coating (Rubipearl 4100, manufactured by Toyo Polymer Co., Ltd.) was mixed with 20% of the above-mentioned fine powder of titanium dioxide having a porous silica-supporting layer, and the mixture containing the photocatalyst was mixed. Ting agent was prepared. The obtained coating agent was applied to glass with a thickness of 50 im to form a coating film, which was irradiated with ultraviolet rays of 5 OmWZcm ² , and the residual ratio of the coating film after 100 hours was measured. As a result of the measurement, the residual ratio was 93%.

Example 2

0.6 g of a commercially available polycarboxylic acid type polymer surfactant (manufactured by Kao Corporation, trade name: BOYS 530) is added to 2.8 L of pure water, and titanium dioxide ultrafine particles (Showa Taiyu Nimu ( 120 g of F4, manufactured by Co., Ltd., having an average primary particle size of 0.03 μm, was dispersed to obtain a titanium dioxide slurry.

Separately, pure water was added to CaC 1 _2, C a after mixing with titanium dioxide slurry ^{2 +} was adjusted salt solution 3.5 L prepared so that 1.8 mM. The diacid 2.5 L of titanium oxide slurry and 3.5 L of salt solution were mixed, and further kept at a temperature of 40 ° C for 24 hours. Thereafter, the slurry was filtered, washed and dried in the same manner as in Example 1 to obtain a fine powder of titanium dioxide supporting the calcium salt of the polymer surfactant.

Using the same method as in Example 1, a titanium dioxide fine powder having a porous silica-supporting layer on its surface was prepared for the obtained calcium salt-supported titanium dioxide fine powder, and a coating film was prepared and evaluated. did. Table 1 shows the results. Analysis of the calcined coating film by infrared absorption spectroscopy (FT-IR method) revealed that the calcium salt of the surfactant had disappeared, and that calcium ions were converted to calcium oxide during the calcining process. Can be

Example 3

50 g of titanium dioxide fine powder having a calcium phosphate supporting layer obtained in the same manner as in Example 1 and 0.02 mol of sodium aluminate were added to 70 Oml of pure water to obtain a titanium dioxide slurry. 0.06 mol of dilute sulfuric acid was added dropwise to the obtained slurry, adjusted to pH 7.2, filtered, washed, and dried (120, 4 hours). Titanium dioxide having a porous alumina-supported layer on its surface A fine powder was obtained. A coating film was prepared and evaluated in the same manner as in Example 1. The results are shown in Table 1.

Example 4

Ethylene glycol 2 mo 1 and water 72 m 1 were added to a slurry obtained by mixing 50 g of titanium dioxide fine powder having a calcium phosphate supporting layer obtained by the same method as in Example 1, zirconium n-butoxide lmo 1 and ethanol 2.5 L. And hydrolyzed. The obtained slurry was filtered, washed, and dried (120 ° C, 4 hours) to obtain a fine titanium dioxide powder having porous zirconia on the surface. A coating film was prepared in the same manner as in Example 1 and evaluated. Table 1 shows the results.

Example 5

Except that the fine powder of titanium dioxide having a calcium phosphate supporting layer used in Example 4 was changed to the fine powder of titanium dioxide supporting a calcium salt of a polymer surfactant obtained by the same method as in Example 2, In the same manner as in Example 4, the porous zircon A fine powder of titanium dioxide supporting nitro was prepared, and a coating film was prepared and evaluated. Table 1 shows the results. In Table 1, the calcium salt of the polymer surfactant is referred to as calcium polycarboxylate.

Comparative Example 1

Using ultrafine titanium dioxide powder (F-4, manufactured by Showa Taiyu Niimu Co., Ltd., average particle diameter of primary particles of 0.03 μm), without forming a calcium phosphate supporting layer and a porous silica supporting layer, A coating film was prepared and evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2

The titanium dioxide fine powder having a calcium phosphate-supporting layer obtained by the same method as in Example 1 (before treatment with a silicone oligomer) was used without forming a porous silica-supporting layer. A coating film was prepared and evaluated in the same manner. Table 1 shows the results.

Comparative Example 3

With respect to titanium dioxide fine powder carrying a calcium salt of a polymeric surfactant obtained by the same method as in Example 2 (before treatment with a silicone oligomer), without forming a porous silica carrying layer In the same manner as in Example 1, a coating film was prepared and evaluated. The results are shown in Table 1.

Comparative Example 4

Titanium dioxide fine powder carrying a calcium salt of a polymeric surfactant (before treatment with a silicone oligomer) obtained by the same method as in Example 2 was calcined at 500 for 10 hours, and calcium oxide was carried. A titanium dioxide fine powder having a layer was obtained. With respect to this titanium dioxide fine powder, a coating film was prepared and evaluated by the same method as in Example 1 without forming a porous silica supporting layer. Table 1 shows the results.

Comparative Example 5

A method similar to that of Example 3 using ultrafine titanium dioxide powder (F-4, manufactured by Showa Taiyu Niimu Co., Ltd., average particle diameter of primary particles: 0.03 μm) without forming a calcium phosphate supporting layer. Titanium dioxide fine powder with porous alumina support layer Powder was prepared, and a coating film was further prepared and evaluated. Table 1 shows the results.

Comparative Example 6

A method similar to that of Example 1 using ultrafine titanium dioxide powder (F-4, manufactured by Showa Taiyu Nihon Co., Ltd., average particle diameter of primary particles: 0.03 μm) without forming a calcium phosphate supporting layer. In this manner, a silicone oligomer was treated to prepare a titanium dioxide fine powder having a porous silicon-carrying layer, and a coating film was prepared and evaluated. Table 1 shows the results.

Comparative Example 7

A method similar to that of Example 4 using ultrafine titanium dioxide powder (F-4, manufactured by Showa Taiyu Niimu Co., Ltd., average particle diameter of primary particles: 0.03 μm) without forming a calcium phosphate supporting layer. Thus, a titanium dioxide fine powder having a porous zirconium-supporting layer was prepared, and a coating film was prepared and evaluated. Table 1 shows the results.

Table 1 1 Porous sparingly soluble calcium compound acetaldehyde Coating film residual carrier layer Material carrier layer Residual rate (%) Rate (%)

― (First support layer) (Second support layer)

Example 1 Calcium Phosphate Silica 59 3 Example 2 Calcium Oxide Silica 39 2 Example 3 Calcium Phosphate Alumina 2 0 95 5 Example 4 Calcium Phosphate Zirconia 1 5 8 8 Example 5 Polycarboxylic Acid Zirconia 1 3 9 0

Calcium salt

Comparative Example 1 0.5 3 5 Comparative Example 2 Calcium phosphate 2 5 5 Comparative Example 3 Polycarboxylic acid 1 5 3

Calcium salt

Comparative Example 4 Calcium Oxide 5 2 Comparative Example 5 — Alumina 7 0 8 5 Comparative Example 6 — Silica 1 0 6 0 Comparative Example 7 — Zirconia 5 0 6 8 As seen in Table 1, the calcium compound supporting layer and the porous material The photocatalyst powder of the present invention (Examples 1 to 5) having a low water-soluble substance-bearing layer has a high photocatalytic performance (the residual ratio of acetoaldehyde is small), and can be used for a long time after being used for a long time. Deterioration effect is small (residual coating rate is large). Photocatalyst powders having only a calcium compound-supporting layer (Comparative Examples 2 to 4) show high photocatalytic performance, but show significant deterioration of the plastic coating medium after long use. In contrast, the photocatalyst powder having only the porous poorly water-soluble substance-supporting layer (Comparative Examples 5 to 7) has low photocatalytic performance (porous silica). (With the exception of Comparative Example 6), but the deterioration of the plastic coating medium after prolonged use is also relatively large). Industrial applicability

The titanium dioxide photocatalyst powder of the present invention exhibits a photocatalytic action by irradiating light, removes offensive odors, decomposes and removes harmful substances or dirt in the air, wastewater treatment and water purification treatment, antibacterial, antibacterial and antifungal properties. Widely used for purifying water. In addition, this environmental purification can be performed effectively, economically and safely. This titanium dioxide catalyst powder is applied to fibers, paper, plastic molded products, etc., or is kneaded into a fiber or plastic medium during the manufacturing process of fibers, plastic molded products, etc., or is in the form of paint, etc. Can be used. The photocatalytic performance is excellent in durability without causing deterioration of the medium.

Since the titanium dioxide photocatalyst powder of the present invention has a support layer of a calcium compound and a porous support layer of a hardly water-soluble substance which is inactive as a photocatalyst, it is used in combination with an organic polymer as a medium. The high photocatalytic action of the titanium dioxide particles lasts for a long time without causing deterioration of the medium. In particular, the titanium dioxide catalyst powder of the present invention exhibits exceptional durability under a strong light irradiation environment such as sunlight.

Claims

The scope of the claims

1. On the surface of the titanium dioxide fine particles, a first support layer containing a calcium compound is provided, and further, on the surface of the titanium dioxide fine particles on which the first support layer is formed, the first support layer is inert as a photocatalyst; A titanium dioxide photocatalyst powder comprising a porous second support layer containing a poorly soluble substance having a solubility product in water of 10 to ²⁵ or less.

2. The titanium dioxide photocatalyst powder according to claim 1, wherein the calcium compound is at least one selected from calcium phosphate, calcium oxide, and a calcium salt of organic rubonic acid.

3. The titanium dioxide photocatalyst powder according to claim 1, wherein the water-insoluble substance inactive as a photocatalyst is at least one selected from silica, alumina, and zirconia.

4. The titanium dioxide photocatalyst powder according to any one of claims 1 to 3, wherein the titanium dioxide fine particles have a primary particle size of 0.01 to 0.2 microns.

5. Platinum, rhodium, ruthenium, palladium, silver, copper, zinc on the surface of the titanium dioxide fine particles, on the surface or in the first support layer, and at least on the surface or in the second support layer. The titanium dioxide photocatalyst powder according to any one of claims 1 to 4, wherein at least one metal selected from the group consisting of:

6. A calcium compound is supported on the surface of the titanium dioxide fine particles to form a first supporting layer, and further, on the surface of the titanium dioxide fine particles on which the first supporting layer is formed, inactive as a photocatalyst; A material capable of forming a hardly soluble substance having a solubility product of 10 to ²⁵ or less in rubbing water is supported thereon, and then dried or calcined to convert the material into the hardly soluble substance. A method for producing a titanium dioxide photocatalyst powder, comprising forming a porous second carrier layer carrying a soluble substance.

7. The method for producing a titanium dioxide photocatalyst powder according to claim 6, wherein the material capable of forming an inert hardly water-soluble substance as a photocatalyst is a silicone oligomer or a silane coupling material.

8. A calcium compound is supported on the surface of the titanium dioxide fine particles to form a first support layer, and an alkali aqueous solution containing metal ions is further applied to the surface of the titanium dioxide fine particles on which the first support layer is formed. By contacting and then neutralizing the aqueous solution, the surface of the titanium dioxide fine particles on which the first supporting layer is formed is inactive as a photocatalyst and has a solubility product of 10 to ^{25 in} water. A method for producing a titanium dioxide photocatalyst powder, comprising forming a porous second support layer containing a poorly soluble substance as described below.

9. The method for producing a titanium dioxide photocatalyst powder according to claim 8, wherein the aqueous alkali solution containing metal ions is an aqueous solution of alkali aluminate, alkali silicate or alkali zirconate.

10. A calcium compound is supported on the surface of the titanium dioxide fine particles to form a first supporting layer, and the metal alkoxide is hydrolyzed on the surface of the titanium dioxide fine particles on which the first supporting layer is formed. Forming a porous second support layer on the surface of the titanium dioxide fine particles that supports a hardly soluble substance that is inactive as a photocatalyst and has a solubility product in water of 10 to ²⁵ or less. A method for producing a titanium dioxide photocatalyst powder, comprising:

11. The method for producing a titanium dioxide photocatalyst powder according to claim 10, wherein the metal alkoxide is an aluminum, silicon or zirconium alkoxide.

12. The method for producing a titanium dioxide photocatalyst powder according to any one of claims 6 to 11, wherein the calcium compound is at least one selected from the group consisting of calcium phosphate, calcium oxide, and calcium salt of organic rubonic acid. .

13. The method for producing a titanium dioxide photocatalyst powder according to any one of claims 6 to 12, wherein a fine particle having a primary particle size of 0.01 to 0.2 micron is used as the titanium dioxide fine particles.

14. A polymer composition comprising an organic polymer as a medium and the titanium dioxide photocatalyst powder according to any one of claims 1 to 5.

15. A polymer molded article obtained by molding the polymer composition according to claim 14.

1 6. The photocatalyst powder according to any one of claims 1 to 4 or the claim 1 4 A structure having on its surface the polymer composition according to item 1.