Patent ID: 6664203
Filing Date: 2003-12-16
Classification: C03C

Abstract:
An alkali-free glass comprising:(A) a composition including: 50 to 70 wt % of SiO2; 7.5 to 20 wt % of Al2O3; 10 to 15 wt % of B2O3; 0 to 5 wt % of ZnO; and 5 to 30 wt % of at least one of MgO, CaO, SrO and Bao, in which an amount of MgO is 0 to 8 wt %, an amount of CaO is 0 to 10 wt %, an amount of SrO is 0 to 8 wt % and an amount of BaO is 0 to 15 wt %; wherein the composition shows a temperature for a viscosity at 102 dPas being equal to or higher than 1,615 Â° C., and the composition does not substantially contain each of ZrO2 and an alkali metal oxide;(B) total tin oxide in an amount of 0.1 to 2 wt %, as a refining agent, based on the weight of the composition (A); and (C) at least one of total cerium oxide, total manganese oxide, total tungsten oxide, total tantalum oxide and total niobium oxide in an amount of 0.1 to 1 wt %, as a refining agent, based on the weight of the composition (A).