Manufacturing method of alkali-free glass

Abstract

The present invention provides a method suitable for producing alkali-free glass having a high strain point, low viscosity, low devitrification, and particularly easy float forming. A method for manufacturing alkali-free glass. Glass raw materials are put into a melting furnace, heated to a temperature of 1400-1800° C. to form molten glass, and then the molten glass is formed into a plate shape by a float method. In the manufacturing method , in the heating in the melting furnace, the heating by the combustion flame of the burner is combined with the electric heating of the molten glass by the heating electrode arranged in such a manner as to be immersed in the molten glass in the melting furnace In use, when the resistivity at 1400° C. of the molten glass is Rg (Ωcm) and the resistivity at 1400° C. of the refractory constituting the melting furnace is Rb (Ωcm), Rb> The glass raw material and the refractory are selected in terms of Rg.

Description

technical field [0001] The present invention relates to a method for producing an alkali-free glass suitable as substrate glasses for various displays and substrate glasses for photomasks. [0002] Hereinafter, in this specification, when referring to "alkali-free", it refers to alkali metal oxides (Li 2 O, Na 2 O, K 2 The content of O) is 2000 ppm or less. Background technique [0003] Conventionally, various substrate glasses for displays, especially substrate glasses on which a metal or oxide thin film or the like has been formed on the surface, have required the following characteristics. [0004] (1) When an alkali metal oxide is contained, the alkali metal ions diffuse into the film to degrade the film properties, so the content of the alkali metal oxide is extremely low, specifically, the content of the alkali metal oxide is 2000 ppm or less. [0005] (2) When exposed to high temperature in the thin film forming process, in order to minimize the deformation of the...

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