| 摘要 |
PURPOSE:To improve coatability and both smoothness and transparency after calcination, by adjusting pH and solid content of an aqueous dispersion of a colloidal hydrated alumina used on a base plate having surface porosity. CONSTITUTION:An aluminum alcoholate solution or an solution of a water soluble aluminum salt is hydrolyzed under such a condition that the relation between pH of the water dispersion of the colloidal hydrated alumina after hydrolysis and the solid content when calcinated at 500 deg.C should be in the range of formula I, especially preferably in the range of formula II to obtain an aqueous dispersion of the colloidal hydrated alumina. As the acid used in hydrolysis, a composition where acetic acid is the main component is preferable in taking into consideration easy handling and stability and working environmental suitability of the aqueous dispersion of the colloidal hydrated alumina. The base plate is coated in a relatively short time at a specific temp. by using these aqueous dispersion and dried to adhere them on the base plate. Then, calcination is carried out at 250 deg.C-550 deg.C for 10min-120min.
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