| 摘要 |
PROBLEM TO BE SOLVED: To obtain a glass having the high glass transition temperature, the same thermal expansion coefficient as that of soda-lime glass, and high fractional toughness by including SiO2, Al2O3, B2O3, an alkaline earth metal oxide, ZrO2 and an alkali metal oxide in specific proportions. SOLUTION: This glass for a substrate comprises 45-65 wt.% SiO2, 6-20 wt.% Al2O3, 0.5-6 wt.% B2O3, 2-5 wt.% MgO, 1-10 wt.% CaO, 0-6.5 wt.% SrO, 0-2 wt.% BaO, 10-17 wt.% (MgO+CaO+SrO+BaO), 0-7 wt.% ZrO and 7-15 wt.% (Na2O+K2O). The physical properties of the glass are preferably >=0.70 MPa.m1/2 fractional toughness, <2.65 specific gravity, >=600 deg.C glass transition temperature and 75×10-7-95×10-7/ deg.C average thermal expansion coefficient at 50-350 deg.C. A transparent glass substrate is obtained by formulating the glass components for the substrate, continuously charging the formulated components to a melting furnace, heating and melting the charged components at 1500-1650 deg.C, forming the melted glass into a plate having a prescribed thickness by a floating method, slowly cooling the formed glass and cutting the cooled glass.
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