ULTAFINE PARTICLE INORGANIC OXIDE SOL OXIDE COMPOSITION FOR COATING SURFACE PROTECTING LAYER OF ARTICLES COATED WITH PRECIOUS METAL THIN FILM AND COATING METHOD USING SAME

摘要

PURPOSE: An ultrafine particle inorganic oxide sol composition containing magnesium silicate as a main component capable of coating without detriment to external appearance while protecting the article surface coated with precious metal at the same time is provided, which gives hardness sufficient for use at low cost. CONSTITUTION: In a coating agent for the protection of the article surface coated with precious metal containing ultrafine particle alkali earth metal aluminosilicate sol represented by the general formula of MO.mAl2O3nSiO2, M is one of metal ions of Mg, Ca, Sr, Ba; m is 0.1 to 2; and n is 0.5 to 3. The method for forming a coating film for the protection of article surface coated with precious metal comprises: treating ultrafine particle alkali earth metal aluminosilicate sol; and forming a coating film for protection having low refractive index and high strength on an alkali earth aluminosilicate coating layer.