Surface-Coated Titanium Dioxide Sol, Process for Producing the Same and Coating Compositions Containing the Same
AssigneeTayca Corporation
InventorNobuyuki Yokoyama
Life of this patent
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Abstract
A transparent titanium oxide in which the titanium oxide particles have been coated with a hydrated metal oxide having no photocatalytic activity in order to block photocatalytic activity. Hydrous titanium oxide sol particles are coated with a layer comprising a hydrated oxide of silicon. The coating layer can further contain a hydrated oxide of at least one metal selected among tin, aluminum, and zirconium and a hydrated oxide of antimony. Also provided are a process for producing a sol of surface-coated transparent titanium oxide and a coating composition containing a sol of surface-coated transparent titanium oxide.
Claims21
1-25. (canceled)
A titanium dioxide sol composition comprising titanium dioxide sol particles having a coating layer thereon and a liquid dispersion medium of the sol, said coating layer comprising hydrated silica in a proportion calculated as SiO2 from 10 to 60% by weight of said titanium dioxide particles calculated as TiO2.
A titanium dioxide sol composition comprising titanium dioxide sol particles having a coating layer thereon and a liquid dispersion medium of the sol, said coating layer comprising:
- (i) hydrated silica in a proportion calculated as SiO2 from 10 to 40% by weight of said titanium dioxide sol particles calculated as TiO2, and
- (ii) at least one hydrated metal oxide selected from the group consisting of tin oxide, aluminum oxide and zirconium oxide in a proportion calculated as sum of SnO2, Al2O3 and ZrO2 from 2 to 40% by weight of said titanium dioxide sol particles calculated as TiO2.
A titanium dioxide sol composition comprising titanium dioxide sol particles having a coating layer thereon and a liquid dispersion medium of the sol, said coating layer comprising:
- (i) hydrated silica in a proportion calculated as SiO2 from 10 to 40% by weight of said titanium dioxide sol particles calculated as TiO2,
- (ii) at least one hydrated metal oxide selected from the group consisting of tin oxide, aluminum oxide and zirconium oxide in a proportion calculated as sum of SnO2, Al2O3 and ZrO2 from 10 to 40% by weight of said titanium dioxide sol particles calculated as TiO2, and
- (iii) hydrated antimony oxide in a proportion calculated as Sb2O5 from 0.5 to 10% by weight of said titanium sol particles calculated as TiO2.
A process for producing a stable titanium dioxide sol composition comprising the steps of:
- (a) providing a titanium dioxide hydrosol;
- (b) adding to said titanium oxide hydrosol a stabilizer selected from the group consisting of hydrogen peroxide, an aliphatic or aromatic hydroxy-carboxylic acid, and an alkoxysilane compound of the formula:
- R1nSiX4-n
- wherein R1 is C1-C8 alky, glycidoxylated C1-C8 alkyl or C2-C8 alkenyl, X is alkoxy, and n is 0 or 1;
- (c) adding the stabilized titanium dioxide hydrosol prepared in step (a) to a solution of a water-soluble silicate salt or silica sol containing an amount of alkali sufficient to keep the mixture alkaline at a pH higher than 9 after said titanium dioxide hydrosol has been added;
- (d) adjusting the pH of the mixture lower than 8, and
- (e) removing electrolytic contaminants from the mixture.
Dependencies are inferred from the claim text.