| 摘要 |
The present invention relates to an alkali-free glass having a strain point of 725°C or higher, an average thermal expansion coefficient at from 50 to 300°C of from 30×10 -7 to 40×10 -7 /°C, a temperature T 2 at which a glass viscosity is 10 2 dPa·s of 1,710°C or lower, and a temperature T 4 at which a glass viscosity is 10 4 dPa·s of 1,320°C or lower, the alkali-free glass including, in terms of mol% on the basis of oxides, SiO 2 : 66 to 70, Al 2 O 3 : 12 to 15, B 2 O 3 : 0 to 1.5, MgO: more than 9.5 and 13 or less, CaO: 4 to 9, SrO: 0.5 to 4.5, BaO: 0 to 1, and ZrO 2 : 0 to 2, in which MgO+CaO+SrO+BaO is from 17 to 21, MgO/(MgO+CaO+SrO+BaO) is 0.4 or more, MgO/(MgO+CaO) is 0.4 or more, MgO/(MgO+SrO) is 0.6 or more, and the alkali-free glass does not substantially contain an alkali metal oxide.
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