| 摘要 |
<p>To provide a glass substrate which has a high glass transition temperature, which has a thermal expansion coefficient close to that of soda lime glass, which has a low specific gravity, which will hardly undergo yellowing, and which further has good melting characters and is thereby produced with high productivity. A glass substrate which has a composition comprising, as represented by mass percentage based on oxides, SiO 2 55 to 65%, Al 2 O 3 4 to 8%, MgO 6 to 9%, CaO 0.1 to 5%, SrO 0.5 to 6%, BaO 0 to 2%, MgO+CaO+SrO+BaO 6.6 to 19%, Na 2 O 0 to 5%, K 2 O 9.5 to 21%, Na 2 O+K 2 O 10 to 22%, ZrO 2 0.5 to 5%, Fe 2 O 3 0.06 to 0.15%,
which has a specific gravity of at most 2.7, which has an average thermal expansion coefficient from 50 to 350°C of from 80×10 -7 °C to 90×10 -7 /°C, which has a glass transition temperature of at least 640°C, and wherein when the viscosity is ·, the temperature at which log·=2 is satisfied is at most 1,550°C, and the yellow coloring b* on the glass surface is at most 8.</p> |
