Processes for producing anatase titanium oxide and titanium oxide coating material

Abstract

Production processes are provided which can produce, at a relatively low temperature and in a reduced number of steps, anatase titanium oxide powder having high photocatalytic activity and large specific surface area and anatase titanium oxide slurry having high storage stability and dispersibility. The slurry thus obtained can also be coated, as a coating material having photocatalytic activity, on materials having low heat resistance. In the production process of anatase titanium oxide powder according to the present invention, a titania sol solution, a titania gel, or a titania sol-gel mixture is heat treated in a closed vessel under pressure, and the treated product is then dried to produce anatase titanium oxide powder. In the production process of anatase titanium oxide slurry according to the present invention, a titania sol solution, a titania gel, or a titania sol-gel mixture is heat treated in a closed vessel under pressure, and the treated product is then dispersed/stirred to produce anatase titanium oxide slurry.

1 . A process for producing anatase titanium oxide, comprising the steps of: 
 heat treating a titania sol solution, a titania gel, or a titania sol-gel mixture in a closed vessel under pressure, said titania sol solution, titania gel, or titania sol-gel mixture containing as a solvent an alcohol having a structure represented by formula C n H 2n+1 OH; and    then ultrasonically dispersing or stirring the treated product to prepare anatase titanium oxide slurry.    
     
     
         2 . A process for producing anatase titanium oxide, comprising the steps of: 
 heat treating a substantially organic solvent-free aqueous titania sol solution, titania gel, or titania sol-gel mixture in a closed vessel under pressure; and    then stirring or ultrasonically dispersing the treated product to prepare aqueous anatase titanium oxide slurry.    
     
     
         3 . A process for producing a titanium oxide coating material, comprising the steps of: 
 providing a titania sol solution, a titania gel, or a titania sol-gel mixture; and    treating the titania sol solution, the titania gel, or the titania sol-gel mixture with ozone gas to produce a titanium oxide coating material.    
     
     
         4 . The process for producing a titanium oxide coating material according to  claim 3 , wherein water, an organic solvent, or a mixture thereof is incorporated as a solvent into the titania sol solution, the titania gel, or the titania sol-gel mixture.  
     
     
         5 . The process for producing a titanium oxide coating material according to  claim 3 , wherein the titanium oxide coating material produced by treating the titania sol solution, the titania gel, or the titania sol-gel mixture with ozone gas is further diluted with an organic solvent.  
     
     
         6 . The process for producing a titanium oxide coating material according to  claim 3 , wherein the titania sol solution, the titania gel, or the titania sol-gel mixture is treated with ozone gas and at least one member selected from the group consisting of titanium oxide powder, titanium oxide slurry, and a mixture thereof is mixed with the treated product to produce a titanium oxide coating material.  
     
     
         7 . The process for producing a titanium oxide coating material according to  claim 3 , wherein at least one member selected from the group consisting of acidic materials, alkaline materials, surfactants, and metal alkoxides other than titanium alkoxides is added to the titania sol solution, the titania gel, or the titania sol-gel mixture.