METHOD FOR PRODUCTION OF NON-ALKALI GLASS

摘要

Disclosed is a method for producing a highly uniform and highly flat non-alkali glass which has few bubbles formed therein. Specifically disclosed is a method for producing a non-alkali glass, which comprises melting a glass raw material comprising a glass base composition raw material containing a silica sand and a boron source and also comprising a clarifying agent and molding the molten material, wherein particles of the silica sand having a D50 value of 15 to 60 µm and a particle diameter of 100 µm or more make up 2.5 vol% or less of the total volume of the particles of the silica sand, the boron source contains anhydrous boric acid in an amount of 10 to 100 mass% relative to 100 mass% of the total amount of the boron source, SnO2 is used as the clarifying agent, and the melting of the glass raw material is carried out by the following steps (a) and (b): (a) heating the glass raw material at a temperature at which the viscosity of the molten glass becomes more than 102.4 dPa·s, thereby producing a molten glass; and (b) heating the molten glass at a temperature at which the viscosity of the molten glass becomes 102.4 dPa·s or less and which is higher by 30°C or more than the temperature employed in the step (a), thereby removing air bubbles from the molten glass.