Photocatalytic powder for environmental clarification and process for producing same, said powder-containing polymer composition, and shaped article of said composition and process for producing same

• US 6,090,736 A
• Filed: 12/28/1998
• Issued: 07/18/2000
• Est. Priority Date: 12/25/1997
• Status: Expired due to Term

• Current Assignee: Hiroshi Taoda, Japan As Represented By Director General of Agency of National Institute of Health, Showa Denko KK, Toru Nonami
• Original Assignee: Agency for Industrial Science and Technology, Hiroshi Taoda, Showa Denko KK, Toru Nonami
• Inventors: Hagihara, Hiroyuki, Ito, Katsura, Nonami, Toru, Taoda, Hiroshi
• Primary Examiner(s): Berman, Susan W.
• Application Number:
  US09/220,762
• Time in Patent Office: 568 Days
• Field of Search: 522/29, 522/28, 522/66, 502/5, 502/159, 502/208, 502/349, 502/350, 526/908, 523/125, 523/126
• US Class Current: 502/5
• CPC Class Codes: B01D 53/885 Devices in general for catalytic purification of waste gases
• CPC Class Codes: B01J 21/063 Titanium; Oxides or hydroxides thereof
• CPC Class Codes: B01J 27/1806 with alkaline or alkaline earth metals
• CPC Class Codes: B01J 35/30 characterised by their physical properties
• CPC Class Codes: B01J 35/39 Photocatalytic properties
• CPC Class Codes: B01J 37/0217 Pretreatment of the substrate before coating
• CPC Class Codes: B01J 37/0219 the coating containing organic compounds
• CPC Class Codes: B01J 37/0221 of particles
• CPC Class Codes: Y10S 502/522 Radiant or wave energy activated
• CPC Class Codes: Y10T 428/2933 Coated or with bond, impregnation or core
• CPC Class Codes: Y10T 428/2938 Coating on discrete and individual rods, strands or filaments
• CPC Class Codes: Y10T 428/2942 Plural coatings
• CPC Class Codes: Y10T 428/2949 Glass, ceramic or metal oxide in coating

Abstract

A photocatalytic powder for environmental clarification, comprising finely divided titanium dioxide particles having a coating of porous calcium phosphate formed on at least part of the surface of each titanium dioxide particle, wherein an anionic surface active agent is present at least on the interface between said coating of porous calcium phosphate and the titanium dioxide particle. This photocatalytic powder is produced by dispersing finely divided titanium dioxide particles in an aqueous slurry containing an anionic surface active agent, and then forming a coating of porous calcium phosphate on at least part of the surface of each titanium dioxide particle. This photocatalytic powder is used, for example, by supporting it in an organic polymer shaped article.

Claims

1. A photocatalytic powder for environmental clarification, comprising finely divided titanium dioxide particles having a coating of porous calcium phosphate formed on at least part of the surface of each finely divided titanium dioxide particle, wherein an anionic surface active agent is present at least on the interface between said coating of porous calcium phosphate and the finely divided titanium dioxide particle.

2. The photocatalytic powder for environmental clarification as claimed in claim 1, wherein the finely divided titanium dioxide particles have an average primary particle diameter of from about 0.001 μ

m to about 0.2 μ

m.

3. The photocatalytic powder for environmental clarification as claimed in claim 1, wherein the finely divided titanium dioxide particles are in the form of a powder comprising primary dispersion particles produced by the gaseous phase reaction starting from a titanium halide.

4. The photocatalytic powder for environmental clarification as claimed in claim 1, wherein the amount of the porous calcium phosphate is in the range of from about 0.01% to about 50% by weight based on the weight of the finely divided titanium dioxide particles.

5. A process for producing a photocatalytic powder for environmental clarification, comprising dispersing finely divided titanium dioxide particles in an aqueous slurry containing an anionic surface active agent, and then forming a coating of porous calcium phosphate on at least part of the surface of each finely divided titanium dioxide particle.

6. The process for producing a photocatalytic powder for environmental clarification as claimed in claim 5, wherein the aqueous slurry used for dispersing the finely divided titanium dioxide particles therein contains from about 0.02 part to about 20 parts by weight of the anionic surface active agent per 100 parts by weight of the finely divided titanium dioxide particles.

7. The process for producing a photocatalytic powder for environmental clarification as claimed in claim 5, wherein the finely divided titanium dioxide particles have an average primary particle diameter of from about 0.001 μ

m to about 0.2 μ

m.

8. The process for producing a photocatalytic powder for environmental clarification as claimed in claim 5, wherein the finely divided titanium dioxide particles are in the form of a powder comprising primary dispersion particles produced by the gaseous phase reaction starting from a titanium halide.

9. The process for producing a photocatalytic powder for environmental clarification as claimed in claim 5, wherein a coating of porous calcium phosphate is formed on at least part of the surface of each finely divided titanium dioxide particle by contacting a pseudo substance solution containing at least calcium ion and phosphate ion with the finely divided titanium dioxide particles whereby porous calcium phosphate is deposited on at least part of the surface of each titanium dioxide particle.

10. The process for producing a photocatalytic powder for environmental clarification as claimed in claim 9, wherein the pseudo substance solution has a calcium ion concentration of from about 0.1 mM to about 50 mM and a phosphate ion concentration of from about 0.1 mM to about 20 mM.

11. A polymer composition comprising an organic polymer and about 0.01% to about 80% by weight, based on the weight of the polymer composition, of a photocatalytic powder for environmental clarification;

said photocatalytic powder comprising finely divided titanium dioxide particles having a coating of porous calcium phosphate formed on at least part of the surface of each finely divided titanium dioxide particle, wherein an anionic surface active agent is present at least on the interface between said coating of porous calcium phosphate and the finely divided titanium dioxide particle.

12. A polymer shaped article having an environmental clarification function, which is obtained by shaping the polymer composition as claimed in claim 11.

13. A process for making a polymer shaped article having an environmental clarification function, which comprises kneading the polymer composition as claimed in claim 11 in an extruder and extruding the polymer composition therefrom.