Titanium dioxide-based photocatalytic coating substrate, and titanium dioxide-based organic dispersions

• US 6,037,289 A
• Filed: 03/12/1998
• Issued: 03/14/2000
• Est. Priority Date: 09/15/1995
• Status: Expired due to Term

• Current Assignee: Saint-Gobain Vitrage, Rhodia Chimie (Solvac SA)
• Original Assignee: Saint-Gobain Vitrage, Rhodia Chimie (Solvac SA)
• Inventors: Talpaert, Xavier, Dupuis, Dominique, Chopin, Thierry, Lehaut, Corinne, Chartier, Pascal
• Primary Examiner(s): Lovering, Richard D.
• Application Number:
  US09/043,063
• Time in Patent Office: 733 Days
• Field of Search: 252/588, 516/33, 106/287.16, 106/287.19, 501/12, 427/160, 427/168, 427/169, 502/351, 502/2
• US Class Current: 502/2
• CPC Class Codes: B01J 35/30 characterised by their physical properties
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01G 23/047 Titanium dioxide
• CPC Class Codes: C01P 2002/02 Amorphous compounds
• CPC Class Codes: C01P 2002/50 Solid solutions
• CPC Class Codes: C01P 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: C01P 2004/86 Thin layer coatings, i.e. the coating thickness being less than 0.1 time the particle radius
• CPC Class Codes: C01P 2006/60 Optical properties, e.g. expressed in CIELAB-values
• CPC Class Codes: C01P 2006/82 water content
• CPC Class Codes: C03C 17/007 containing a dispersed phase, e.g. particles, fibres or flakes, in a continuous phase
• CPC Class Codes: C03C 17/008 comprising a mixture of materials covered by two or more of the groups C03C17/02, C03C17/06, C03C17/22 and C03C17/28
• CPC Class Codes: C03C 17/2456 Coating containing TiO2
• CPC Class Codes: C03C 17/256 Coating containing TiO2
• CPC Class Codes: C03C 2217/212 TiO2
• CPC Class Codes: C03C 2217/29 Mixtures
• CPC Class Codes: C03C 2217/45 Inorganic continuous phases
• CPC Class Codes: C03C 2217/477 Titanium oxide
• CPC Class Codes: C03C 2217/71 Photocatalytic coatings
• CPC Class Codes: C03C 8/20 containing titanium compounds; containing zirconium compounds
• CPC Class Codes: C04B 41/5041 Titanium oxide or titanates
• 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: C09D 1/00 : Coating compositions, e.g. paints, varnishes or lacquers, based on inorganic substances
• CPC Class Codes: C09D 17/008 : Titanium dioxide
• CPC Class Codes: C23C 18/1216 : Metal oxides C23C18/1212 takes precedence
• CPC Class Codes: C23C 18/1225 : Deposition of multilayers of inorganic material
• CPC Class Codes: C23C 18/1245 : Inorganic substrates other than metallic
• CPC Class Codes: C23C 18/1254 : Sol or sol-gel processing
• CPC Class Codes: C23C 18/1258 : Spray pyrolysis
• CPC Class Codes: C23C 18/127 : Preformed particles
• CPC Class Codes: C23C 18/1295 : with after-treatment of the deposited inorganic material
• CPC Class Codes: C23C 26/00 : Coating not provided for in groups C23C2/00 - C23C24/00
• CPC Class Codes: C23C 30/00 : Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process C23C26/00, C23C28/00 take precedence
• CPC Class Codes: Y02T 50/60 : Efficient propulsion technologies, e.g. for aircraft
• CPC Class Codes: Y10S 502/522 : Radiant or wave energy activated

Abstract

The invention relates to a substrate provided, on at least a portion of one of its faces, with a coating with a photocatalytic property based on titanium dioxide which is at least partially crystalline and which is incorporated in the said coating partly in the form of particles predominantly crystallized in the anatase form. The invention also relates to a process for the preparation of this substrate and organic dispersions of titanium dioxide particles used in the said process for the preparation of the substrate.

Claims

1. A substrate provided, on at least a portion of one of its faces, with a coating with a photocatalytic property based on titanium dioxide which is at least partially crystalline and which is incorporated in said coating partly in the form of particles predominantly crystallized in the anatase form, said particles being incorporated in the coating using an inorganic binder, and wherein at least one thin layer with an anti-static, thermal or optical function or forming a barrier to the migration of alkali metals originating from the substrate, is arranged under the coating based on titanium dioxide.

2. A substrate according to claim 1, wherein the size of particles is between 5 and 80 nm.

3. A substrate according to claim 1, wherein the binder is in the form of an amorphous or partially crystalline oxide or mixture of oxides selected from the group consisting of silicon oxide, titanium oxide, tin oxide, zirconium oxide and aluminum oxide.

4. A substrate according to claim 3, wherein the coating exhibits a refractive index of between 1.40 and 2.35.

5. A substrate according to claim 4, wherein the coating exhibits a refractive index of between 1.6 and 2.3.

6. A substrate according to claim 1, wherein the binder is at least partly organic.

7. A substrate according to claim 1, wherein at least a portion of the titanium dioxide particles comprise, in their crystal lattice, metal ions selected from the group consisting of iron, copper, ruthenium, cerium, molybdenum, bismuth, tantalum, nickel, and vanadium.

8. A substrate according to claim 1, wherein at least a portion of the titanium dioxide particles are covered at least in part by a layer of metal oxides or salts, the metal being selected from the group consisting of iron, copper, ruthenium, cerium, molybdenum, bismuth, tantalum, cobalt, nickel, vanadium, tungsten, tin, zirconium, cadmium, and zinc.

9. A substrate according to claim 8, wherein at least a portion of the titanium dioxide particles are covered at least partly by a layer of metal selected from the group consisting of platinum, silver and rhodium.

10. A substrate according to claim 1, wherein the coating comprises additive particles based on cadmium, tin, tungsten, zinc, cerium or zirconium.

11. A substrate according to claim 1, wherein the thickness of the coating is between 5 nm and 1 micron.

12. A substrate according to claim 11, wherein the thickness of the coating is between 5 mn and 100 nm.

13. A substrate according to claim 1, wherein said substrate is based on glass, ceramic or vitroceramic.

14. A substrate according to claim 1, wherein the thin layer is a conductive material which is a metal or doped metal oxide.

15. A substrate according to claim 14, wherein the thin layer is a doped metal oxide selected from the group consisting of indium oxide doped with tin ITO, tin oxide doped with fluorine SnO₂ :

F, zinc oxide doped with indium ZnO;

In, zinc oxide doped with fluorine ZnO;

F, zinc oxide doped with aluminum ZnO;

Al, and zinc oxide doped with tin ZnO;

Sn.

16. A substrate according to claim 14, wherein the coating constitutes the final layer of a stack of anti-glare layers.

17. A monolithic glazing or multiple glazing of the double glazing or laminated type incorporating a substrate according to claim 1.

18. A process for producing a substrate provided, on at least a portion of one of its faces, with a coating with a photocatalytic property based on titanium dioxide which is at least partially crystalline and which is incorporated in said coating partly in the form of particles predominantly crystallized in the anatase form, said particles being incorporated in the coating using an inorganic binder, comprising the step of depositing and heat treating the coating, from a dispersion comprising at least one organometallic compound and titanium dioxide particles, said particles being predominantly crystallized in the anatase form.

19. A process for producing a substrate according to claim 18, wherein the coating is deposited by a sol-gel technique, with a method of deposition of dip-coating, cell-coating, lamninar-coating or spray-coating, from a dispersion comprising at least one organometallic compound and titanium dioxide particles, said particles being predominantly crystallized in the anatase form.

20. A process according to claim 19, wherein the dispersion has a ratio of the mass of the organometallic compounds, expressed as metal oxides (MO_x), with respect to the weight of TiO₂ contributed by the particles and of the organometallic compounds, expressed as metal oxides (MO_x), between 5 and 80%.

21. A process according to claim 19, wherein the organometallic compounds are based on titanium or on silicon.

22. A process according to claim 19, comprising the step of depositing the coating in at least two successive stages.

23. A process according to claim 22, comprising the step of subjecting the coating, after deposition, to at least one heat treatment.

24. A process for producing a substrate provided, on at least a portion of one of its faces, with a coating with a photocatalytic property based on titanium dioxide which is at least partially crystalline and which is incorporated in said coating partly in the form of particles predominantly crystallized in the anatase form, said particles being incorporated in the coating using an inorganic binder, comprising the step of depositing the coating by liquid phase pyrolysis, from a dispersion comprising one or more organometallic compounds and titanium dioxide particles, said particles being predominantly crystallized in the anatase form.

25. A process according to claim 24, wherein the dispersion has a ratio of the mass of the organometallic compounds, expressed as metal oxides (MO_x), with respect to the weight of TiO₂ contributed by the particles and of the organometallic compounds, expressed as metal oxides (MO_x), between 5 and 80%.

26. A process according to claim 24, wherein the organometallic compounds are based on titanium or on silicon.

27. An organic dispersion, comprising:

titanium dioxide particles with a size of between 5 and 80 nm which are monodisperse and predominantly in the anatase crystalline form,

at least one organometallic compound, and

at least one organic solvent.

28. An organic dispersion according to claim 27, wherein the organic solvent exhibits a latent heat of vaporization which is less than that of water.

29. A dispersion according to claim 27, wherein the organic solvent is an alcohol or an ester.

30. A dispersion according to claim 27, wherein the titanium dioxide particles result from a solution preparation process.

31. A dispersion according to claim 30, wherein the titanium dioxide particles are prepared by hydrolysing at least one titanium compound A in the presence of at least one compound B selected from the group consisting of:

(i) acids which exhibit;

either a carboxyl group and at least two hydroxyl and/or amine groups,

or at least two carboxyl groups and at least one hydroxyl and/or amine group,

(ii) organic phosphoric acids of following formulae;

##STR4## in which n and m are integers of between 1 and 6 and p is an integer of between 0 and 5, R1, R2 and R3, which are identical or different, representing a hydroxyl, amino, aralkyl, aryl or alkyl group or hydrogen,

(iii) compounds capable of releasing sulphate ions in acidic medium, and

(iv) salts of the acids described above, in the presence of anatase titanium dioxide seeds exhibiting a size of at most 5 nm and in a ratio by weight of TiO₂ present in the seeds/titanium present before introduction of the seeds in the hydrolysis medium, expressed as TiO₂, of between 0.01% and 3%.

32. A dispersion according to claim 30, wherein the particles are porous.

33. A dispersion according to claim 27, further comprising at least one organometallic compound whose metal is titanium, silicon, tin, zirconium or aluminum.

34. A dispersion according to claim 33, wherein the organometallic compound is a compound of general formula M(OR)₄ in which M is titanium, silicon, tin, zirconium or aluminum and R an alkyl, cycloalkyl, aryl, alkylaryl or arylalkyl, alkenyl or alkynyl group, an acetylacetonate group, an amino group, or a glycolate.

35. A dispersion according to claim 27, wherein the proportion of the organometallic compounds is such that the ratio of the mass of these organometallic compounds, expressed as metal oxides (MO_x), with respect to the weight of TiO₂ contributed by the particles and of the organometallic compounds, expressed as metal oxides (MO_x), is between 5 and 80%.

36. A dispersion according to claim 27, comprising additive particles based on metal compounds whose metal is cadmium, tin, tungsten, zinc, cerium or zirconium.

37. A dispersion according to claim 27, wherein at least a portion of the titanium dioxide particles of the dispersion is doped in their crystal lattice by metal ions whose metal is iron, copper, ruthenium, cerium, molybdenum, bismuth, tantalum, cobalt, nickel or vanadium.

38. A dispersion according to claim 27, wherein at least a portion of the titanium dioxide particles of the dispersion are at least partly covered by a layer of metal oxides or salts, whose metal is iron, copper, ruthenium, cerium, molybdenum, bismuth, tantalum, cobalt, nickel, vanadium, tungsten, tin, zirconium, cadmium or zinc.

39. A dispersion according to claim 27, wherein at least a portion of the titanium dioxide particles of the dispersion is at least partly covered by a catalyst.

40. A dispersion according to claim 39, wherein said catalyst is platinum, silver or rhodium.