PROCESS FOR PRODUCTION OF NON-ALKALINE GLASS AND NON-ALKALINE GLASS

摘要

The invention provides a process for the production of non-alkaline glass which is effectively depressed in foaming; and non-alkaline glass produced by the process which little contains bubbles and is favorably usable as the glass substrate for flat panel displays. A process for the production of non-alkaline glass which comprises the step of melting a glass raw material which is substantially free from alkali metal oxides and has a parent composition described below and the treatment step of subjecting the molten glass in contact with a platinum member to vacuum defoaming, stirring, or transfer, wherein a raw material comprising 100 wt% of the parent composition and 0.01 to 2.0 wt% of SnO₂ is prepared and melted under heating to 1500 to 1650ºC; the bubbles contained in the molten glass together with oxygen bubbles generated by the reduction of the SnO₂ into SnO are made to float on the surface of the molten glass; and in the above treatment step, the oxygen bubbles generated on the interface between the molten glass and the platinum member are absorbed by the oxidation of the SnO into SnO₂ with the molten glass kept at 1300 to 1500ºC: Composition in terms of weight percentage SiO₂: 58.4 to 66.0%, Al₂O₃: 15.3 to 22.0%, B₂O₃: 5.0 to 12.0%, MgO: 0 to 6.5%, CaO: 0 to 7.0%, SrO: 4 to 12.5%, BaO: 0 to 2.0%, and (MgO + CaO + SrO + BaO): 9.0 to 18.0%.