PURPOSE:To obtain a glass article resistant to discoloration with radiation of electron ray, by contacting soda-lime silica glass with a molten salt containing K to substitute the Na in the surface layer of the glass with K and heat-treating the product. CONSTITUTION:A soda-lime silica glass is made to contact with a molten salt containing potassium ion to substitute the sodium ion in the surface layer of the glass with potassium ion and the product is heat-treated. The surface layer extending from the surface to the intrusion depth of the radiated electron ray has a Na2O/(Na2O+K2O) molar ratio of 0.4-0.65. When the K -containing molten salt is potassium nitrate, the molten salt is maintained preferably at 440-480 deg.C and is made to contact with the glass for preferably 0.5-4hr. The heat-treatment is preferably carried out at 440-480 deg.C for 1-10hr.

Shibaoka Kazuo

Papers

Method for producing glass article resistant to discoloration with electron ray