METHOD FOR MANUFACTURING ALKALI-FREE GLASS SUBSTRATE AND ALKALI-FREE GLASS SUBSTRATE

摘要

Provided is an alkali-free glass substrate having a high strain point and excellent bubble count, and a method for manufacturing the alkali-free glass substrate. The method includes: a batch preparing process of preparing a raw material batch so as to obtain alkali-free glass containing, in mass %, 50 to 80% of SiO₂, 15 to 30% of Al₂O₃, 0 to 4.5% of B₂O₃, 0 to 10% of MgO, 0 to 15% of CaO, 0 to 10% of SrO, 0 to 15% of BaO, 0 to 5% of ZnO, 0 to 5% of ZrO₂, 0 to 5% of TiO₂, 0 to 15% of P₂O₅ and 0 to 0.5% of SnO₂ as a glass composition; a melting process of melting the prepared raw material batch; a fining process of fining the molten glass; and a forming process of forming the fined glass into a sheet shape. The raw material batch is melted such that a bubble enlarging temperature of the obtained glass is lower than a maximum temperature of the fining process.