Method of forming metal oxide film by using metal alkoxide solution
First Claim
1. A method of forming a metal oxide film on a substrate, the method having the steps of preparing a solution of at least one metal alkoxide, adjusting the viscosity of the alkoxide solution by adding thereto a viscosity adjusting agent, thereafter applying the alkoxide solution to the substrate to form a sol film on the substrate, drying the sol film to cause the sol film to turn into a gel film and baking the gel film to a temperature sufficient to convert the gel film to the metal oxide film,characterized in that said viscosity adjusting agent is a combination of a first hydroxypropyl cellulose of which 2 wt % aqueous solution has a viscosity in the range from 150 to 400 centipoises at 20°
- C. and a second hydroxypropyl cellulose of which 2 wt % aqueous solution has a viscosity in the range from 6 to 10 centipoises at 20°
C., wherein the proportion of said first hydroxypropyl cellulose to said second hydroxypropyl cellulose is in the range from 70;
30 to 97;
3 by weight.
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Abstract
The invention relates to a sol-gel method for forming a metal oxide film, e.g. TiO2 film or TiO2 -SiO2 film, on a substrate by applying a solution of at least one metal alkoxide to the substrate to form a sol film on the substrate, drying the sol film to cause it to turn into a gel film by hydrolysis and baking the gel film. According to the invention the viscosity of the metal alkoxide solution is adequately increased, preferably to 3-30 cP at 20° C., by the addition of a combination of a hydroxypropyl cellulose of which 2 wt % aqueous solution has a viscosity of 150-400 cP at 20° C. and another hydroxypropyl cellulose of which 2 wt % aqueous solution has a viscosity of 6-10 cP at 20° C. Metal oxide films formed by this method are free from minute cracks and excellent in optical characteristics and durability. By this method it is possible to form a metal oxide film as thick as about 300 nm without repeating the application of the alkoxide solution to the substrate.
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Citations
9 Claims
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1. A method of forming a metal oxide film on a substrate, the method having the steps of preparing a solution of at least one metal alkoxide, adjusting the viscosity of the alkoxide solution by adding thereto a viscosity adjusting agent, thereafter applying the alkoxide solution to the substrate to form a sol film on the substrate, drying the sol film to cause the sol film to turn into a gel film and baking the gel film to a temperature sufficient to convert the gel film to the metal oxide film,
characterized in that said viscosity adjusting agent is a combination of a first hydroxypropyl cellulose of which 2 wt % aqueous solution has a viscosity in the range from 150 to 400 centipoises at 20° - C. and a second hydroxypropyl cellulose of which 2 wt % aqueous solution has a viscosity in the range from 6 to 10 centipoises at 20°
C., wherein the proportion of said first hydroxypropyl cellulose to said second hydroxypropyl cellulose is in the range from 70;
30 to 97;
3 by weight. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
- C. and a second hydroxypropyl cellulose of which 2 wt % aqueous solution has a viscosity in the range from 6 to 10 centipoises at 20°
Specification