| 摘要 |
PURPOSE:To provide the title sol which gives a coating film having a thickness which can be easily controlled without causing cracking and forming any void or any pinhole, containing colloidal zirconia sol obtd. by hydrolyzing an aq. zirconium salt soln. CONSTITUTION:An aq. soln. of a water-soluble zirconium salt such as zirconyl chloride, zirconyl acetate, etc. is hydrolyzed. The solvent contg. anions and unreacted metal ions is removed by filtration, and the residue is washed with pure water. The pH thereof is adjusted to 5-9 by adding a basic matcrial (e.g., NaOH) and the resulting product is washed with pure water and dehydrated by adding an alcohol including polyhydric clcohol to obtain an org. solvent (A) contg. 0.01-20wt% (in terms of ZrO2 colloidal zirconia sol having an average particle size of 300-1,500Angstrom . If desired, 0.01-0.5wt% at least one sol (B) selected from the group consisting of alumina sol, silica sol and titania sol is added to the component A. The mixture is applied to a substrate and exposed to an atmosphere at a relative humidity of 70-95% and 30-70 deg.C for one hr or longer. The relative humidity is lowered to 10-40% and the substrate is heated to 100-500 deg.C at a heating rate of 0.2-5 deg.C/min to form a coating film having a thickness of 0.5-10mum. |
