| 摘要 |
Disclosed is a process for producing a glass substrate for an information recording medium by press-shaping a molten glass which gives a glass containing 0.1 to 30 mol % of TiO2, 1 to 45 mol % of CaO, 5 to 40 mol % of total of MgO and the above CaO, 3 to 30 mol % of total of Na2O and Li2O, 0 to 15 mol % of Al2O3 and 35 to 65 mol % of SiO2 and having properties of a liquidus temperature of 1,360° C. or lower and a viscosity of at least 10 poise in a shaping-allowable temperature range, or by preparing a preform formed of a glass which contains 0.1 to 30 mol % of TiO2, 1 to 45 mol % of CaO, 5 to 40 mol % of total of MgO and the above CaO, 3 to 30 mol % of total of Na2O and Li2O, 0 to 15 mol % of Al2O3 and 35 to 65 mol % of SiO2 and has properties of a liquidus temperature of 1,360° C. or lower and shaping the preform in the form of a disc by a re-heat pressing method. According to the above process, there can be mass-produced, with high productivity, high-quality glass substrates to be used for information recording media such as a magnetic disc, an optical disc, a magneto-optic disc, and the like.
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