PROCESS FOR PRODUCING ALKALI-FREE GLASS SUBSTRATE

摘要

A process for producing an alkali-free glass substrate in which a protective coating film capable of being easily removed in a cleaning step is efficiently formed and the back side of the glass substrate is inhibited from being marred while reducing the amount of sulfur dioxide to be used; and an alkali-free glass substrate obtained by the process. The process for alkali-free glass substrate production produces an alkali-free glass substrate by the float method. It comprises a forming step in which a molten glass is formed on molten tin into a glass substrate and an annealing step in which the glass substrate formed in the forming step is annealed. The process further comprises a first supply step in which an inorganic substance containing an alkali metal is blown against that surface of the glass substrate which was in contact with the molten tin and a second supply step in which after the first supply step, SO2 gas is blown against that surface of the glass substrate which was in contact with the molten tin.