Multi-functional material with photocatalytic functions and method of manufacturing same

• US 6,027,797 A
• Filed: 10/07/1998
• Issued: 02/22/2000
• Est. Priority Date: 12/10/1993
• Status: Expired due to Term

• Current Assignee: Toto Limited
• Original Assignee: Toto Limited
• Inventors: Hayakawa, Makoto, Watanabe, Toshiya, Kitamura, Atsushi, Kojima, Eiichi, Machida, Mitsuyoshi, Nakashima, Yasushi, Kuga, Tatsuhiko, Chikuni, Makoto, Norimoto, Keiichiro, Kimura, Tamon, Saeki, Yoshimitsu
• Primary Examiner(s): Copenheaver, Blaine
• Application Number:
  US09/167,324
• Time in Patent Office: 503 Days
• Field of Search: 428/312.8, 428/313.9, 428/317.7, 430/947, 502/242, 502/309, 502/439, 427/125, 427/126.2, 427/126.5, 427/126.6, 427/214, 427/217
• US Class Current: 428/312.8
• CPC Class Codes: B01J 21/063 Titanium; Oxides or hydroxides thereof
• CPC Class Codes: B01J 35/30 characterised by their physical properties
• CPC Class Codes: B01J 35/39 Photocatalytic properties
• CPC Class Codes: B01J 37/0215 Coating
• CPC Class Codes: C03C 17/007 containing a dispersed phase, e.g. particles, fibres or flakes, in a continuous phase
• CPC Class Codes: C03C 17/3411 with at least two coatings of inorganic materials C03C17/36, C03C17/42 take precedence
• CPC Class Codes: C03C 2217/42 consisting of particles only
• CPC Class Codes: C03C 2217/425 consisting of a porous layer
• CPC Class Codes: C03C 2217/475 Inorganic materials
• CPC Class Codes: C03C 2217/477 Titanium oxide
• CPC Class Codes: C03C 2217/71 Photocatalytic coatings
• CPC Class Codes: C04B 33/00 Clay-wares monolithic refractories or refractory mortars C04B35/66; porous products C04B38/00
• CPC Class Codes: C04B 35/10 based on aluminium oxide
• CPC Class Codes: C04B 41/0045 Irradiation; Radiation, e.g. with UV or IR C04B41/0036 takes precedence
• CPC Class Codes: C04B 41/009 characterised by the material treated
• CPC Class Codes: C04B 41/4535 applied as a solution, emulsion, dispersion or suspension
• CPC Class Codes: C04B 41/4537 by the sol-gel process
• CPC Class Codes: C04B 41/4539 as a emulsion, dispersion or suspension
• CPC Class Codes: C04B 41/455 the coating or impregnating process including a chemical conversion or reaction
• CPC Class Codes: C04B 41/4554 the coating or impregnating material being an organic or organo-metallic precursor of an inorganic material
• CPC Class Codes: C04B 41/4562 : Photographic methods, e.g. making use of photo-sensitive materials
• CPC Class Codes: C04B 41/5022 : with vitreous materials composition of vitreous glazes and enamels C03C; ceramic pigments C09C1/0009
• CPC Class Codes: C04B 41/5041 : Titanium oxide or titanates
• CPC Class Codes: C04B 41/505 : Tin oxide
• CPC Class Codes: C04B 41/51 : Metallising , e.g. infiltration of sintered ceramic preforms with molten metal covering materials with metals in general C23C; ceramic compositions containing free metal bonded to carbides, diamond, oxides, borides, nitrides, silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides or sulfides, other than as macroscopic reinforcing agents C22C; infiltration of preforms containing free metal, e.g. cermets C22C
• CPC Class Codes: C04B 41/5111 : Ag, Au, Pd, Pt or Cu
• CPC Class Codes: C04B 41/52 : Multiple coating or impregnating multiple coating or impregnating with the same composition or with compositions only differing in the concentration of the constituents, is classified as single coating or impregnation
• CPC Class Codes: C04B 41/81 : Coating or impregnation
• CPC Class Codes: C04B 41/89 : for obtaining at least two superposed coatings having different compositions
• CPC Class Codes: Y10S 430/148 : Light sensitive titanium compound containing
• CPC Class Codes: Y10T 428/24909 : Free metal or mineral containing
• CPC Class Codes: Y10T 428/24997 : Of metal-containing material
• CPC Class Codes: Y10T 428/249974 : Metal- or silicon-containing element
• CPC Class Codes: Y10T 428/249982 : With component specified as adhesive or bonding agent
• CPC Class Codes: Y10T 428/249985 : Composition of adhesive or bonding component specified

Abstract

Multi-functional materials which have a photocatalytic layer with a photocatalytic function disposed on the surface of a base through a binder layer 6 interposed therebetween. Photocatalytic particles of the photocatalytic layer are joined together by a surface energy or solid-state sintering. The photocatalytic layer may have a structure in which fine particles fill interstices defined between photocatalytic particles or a structure in which no fine particles fill interstices defined between photocatalytic particles. A metal such as Ag, Pt, or the like may be fixed or not fixed to surfaces of the photocatalytic particles.

Claims

1. A multi-functional material with a photocatalytic function, comprising:

a base;

a photocatalytic layer having a photocatalytic function and disposed on a surface of said base, said photocatalytic layer including at least a surface layer exposed outwardly, said surface layer being composed of fine photocatalytic particles joined together with interstices defined therebetween at a predetermined porosity;

said surface layer being further composed of electron-capturing particles fixed to surfaces of the photocatalytic particles;

said photocatalytic layer comprise a thin rutile TiO₂ film; and

said electron-capturing particles being made of at least one of Cu, Ag, Fe, Co, Pt, Ni, Pd, and Cu₂ O.

2. A multi-functional material according to claim 1, wherein said thin rutile TiO₂ film comprises a porous body having a porosity of 10% or more.

3. A multi-functional material according to claim 1, wherein said thin rutile TiO₂ film has a thickness in a range of 0.1 μ

m-0.9 μ

m.

4. A multi-functional material according to claim 1, wherein said electron-capturing particles of at least one of Cu, Ag, Fe, Co, Pt, Ni, Pd, and Cu₂ O have an average crystal diameter smaller than the average diameter of pores of said thin rutile TiO₂ film.

5. A multi-functional material according to claim 1, wherein said electron-capturing particles comprise at least one of Cu and Cu₂ O, said particles being fixed to said thin rutile TiO₂ film in an amount per unit area in a range of 0.12 μ

g/cm² -1.2 μ

g/cm².

6. A multi-functional material according to claim 1, wherein said electron-capturing particles comprise at least one of Cu and Cu₂ O, said particles being fixed to said thin rutile TiO₂ film in an amount per unit area of at least 0.7 μ

g/cm².

7. A multi-functional material according to claim 1, wherein said electron-capturing particles comprise Ag, said Ag particles being fixed to said thin rutile TiO₂ film in an amount per unit area in a range of 0.05 μ

g/cm² -1 μ

g/cm².

8. A multi-functional material according to claim 1, wherein said joined photocatalytic particles in said surface layer have necks formed therebetween.

9. A multi-functional material according to claim 1, further including another material reacted with said electron capturing particles to form a colorless or white salt on at least surfaces of the electron capturing particles.

10. A multi-functional material according to claim 1, wherein said photocatalytic layer further includes fine SnO₂ particles provided together with said photocatalytic particles;

said SnO₂ particles having a smaller average crystal diameter than that of said photocatalytic particles, and said SnO₂ particles are provided in a range of 10-80 wt % relative to a total weight of the photocatalytic particles and the SnO₂ particles in the photocatalytic layer.

11. A multi-functional material according to claim 1, wherein said electron capturing particles are uniformly fixed to the surfaces of the photocatalytic particles by coating an aqueous solution of salt of at least one of Cu, Ag, Pt, Fe, Co, Ni, Pd, and Cu₂ O on the surface layer and then photoreducing or heating the coated solution.

12. A multi-fuictional material according to claim 1, wherein said photocatalytic particles used in forming said photocatalytic layer have an average crystal diameter of ≦

0.04 μ

m.

13. A method of manufacturing a multi-functional material with a photocatalytic function, comprising the steps of:

forming a photocatalytic layer having a photocatalytic function on a surface of a base, said photocatalytic layer comprising a thin rutile TiO₂ film with at least a surface layer exposed outwardly, said surface layer being composed of fine photocatalytic particles joined together with interstices defined therebetween at a predetermined porosity;

coating at least one of an aqueous solution of a metal salt of at least one of Ni, Pd, and Pt and an ethanol solution of a metal salt on said surface layer; and

thereafter irradiating the coated solution with light containing ultraviolet rays to reduce metal ions to fix a metal to surfaces of said photocatalytic particles.

14. A method according to claim 13, wherein said thin rutile TiO₂ film comprises a porous body having a porosity of 10% or greater.

15. A method according to claim 13, including a further step of drying said coated aqueous solution and said ethanol solution before said irradiating step.

16. A method according to claim 13, including a further step of forming a binder layer between said thin rutile TiO₂ film and said base such that said thin rutile TiO₂ film is formed on the surface of the base through said binder layer.

17. A method according to claim 13, wherein said thin rutile TiO₂ film has a thickness ranging from 0.1 μ

m to 0.9 μ

m.

18. A method of manufacturing a multi-functional material with a photocatalytic function, comprising the steps of:

forming a photocatalytic layer having a photocatalytic function on a surface of a base, said photocatalytic layer comprising a thin rutile TiO₂ film with at least a surface layer exposed outwardly, said surface layer being composed of fine photocatalytic particles joined together with interstices defined therebetween at a predetermined porosity;

coating an aqueous solution of at least one of a Cu salt and an Ag salt on said surface layer; and

thereafter irradiating the coated solution with light containing ultraviolet rays to reduce at least one of Cu and Ag ions for thereby fixing at least one of Cu and Ag to surfaces of the photocatalytic particles.

19. A method according to claim 18, wherein said aqueous solution contains the Cu salt, and Cu is fixed to the thin rutile TiO₂ film in an amount ranging from 1.2 μ

g/cm² to 10 μ

g/cm².

20. A method according to claim 18, wherein said aqueous solution contains the Ag salt, and Ag is fixed to the thin rutile TiO₂ film in an amount ranging from 0.1 μ

g/cm² to 1 μ

g/cm².