Patent ID: 7605186

Claim:
A method of manufacturing a neutral and transparent metal oxide colloid solution containing dispersed titanium dioxide nano particles, comprising the following steps: (i) adding a titanium compound and a stabilizer to alcohol to produce a titanium-containing solution, the stabilizer being selected from the group consisting of: glycolic acid, glycolic salt, oxalic acid, pentanediol, pentanedione, butanedione, alkylacetoacetate, polyethyleneglycol, cetyltrimethyl ammonium hydroxide, polyvinyl acetate, polyvinyl alcohol, trialkanolamine and a mixture thereof, and the titanium compound being selected from the group consisting of titanium(IV) isopropoxide, titanium(IV) butoxide, titanium(IV) ethoxide, titanium(IV) methoxide, titanium(IV) stearate and a mixture thereof; (ii) neutralizing the titanium-containing solution of the previous step by adding a basic solution to produce a neutralized solution, pH of the neutralized solution being controlled in a range of 6-8; (iii) heating the neutralized solution at a temperature of above 75° C., (iv) slowly adding distilled water to the titanium-containing solution in steps (i) and (ii) while stirring, wherein in step (i), the titanium compound and the stabilizer can be added in any order, and wherein 40% (w/w) aqueous titanium tetrachioride solution is added prior to adding the stabilizer and after adding the titanium compound to the alcohol in step (i).