GLASS COMPOSITION FOR SUBSTRATE AND METHOD FOR PRODUCING THE SAME

摘要

Disclosed is a glass composition for substrates which has excellent productivity by lowering high-temperature viscosity, while assuring characteristics and quality required for FPD substrates, particularly for PDP substrates. Specifically disclosed is a glass composition for substrates which is characterized by containing, in mol% based on oxides, 55-75% of SiO2, 5-15% of Al2O3, 4-18% of MgO, 3-12% of CaO, 4-18% of SrO, 0-20% of BaO, 6-20% of Na2O + K2O, 0.5-6% of ZrO2 and 18-25% of MgO + CaO + SrO + BaO as a glass matrix composition, and containing 0.001-0.6% of SO3. The glass composition for substrates is also characterized in that when the viscosity is represented by ?, the temperature satisfying log ? = 2 is not more than 1545°C, and the devitrification temperature is lower than the temperature satisfying log ? = 4. The glass composition for substrates is further characterized by having a thermal expansion coefficient of from 75 x 10-7 to 90 x 10-7 /°C, a specific gravity of not more than 2.8, and a glass transition temperature of not less than 600°C.