| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a titanium oxide coating film having large antase-type titanium oxide content by bringing a supersaturated solution of titanium oxide obtained by adding a specific additive to an aqueous solution of ammonium titanium fluoride into contact with a substrate to form the titanium oxide coating film on the surface of the substrate. SOLUTION: A supersaturated solution of titanium oxide is obtained by adding 0.02-0.2 mol/L, preferably 0.1-0.2 mol/L aluminum chloride as an additive for moving an equilibrium of the formula; (NH4 )2 TiF6 +2H2 O←↑TiO2 +4HF+2 NH4 F to the right, and ammonia of 1.0-2.0 times as much as the amount of the ammonium chloride, to an aqueous solution containing 0.008-0.5 mol/L ammonium titanium fluoride. The supersaturated solution of the titanium oxide is heated to 25-100 deg.C, and a substrate is dipped into the heated supersaturated solution to precipitate the titanium oxide coating film on the surface of the substrate. As the result, the fear of decrease of the precipitation rate of the titanium oxide and enlargement of an impurity content taken in the titanium oxide is diminished.
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