| 摘要 |
<p>The present invention relates to an alkali-free glass having a strain point of 710°C or higher, an average thermal expansion coefficient at from 50 to 350°C of from 30×10 -7 to 43×10 -7 /°C, a temperature T 2 at which glass viscosity reaches 10 2 dPa·s of 1,710°C or lower, and a temperature T 4 at which the glass viscosity reaches 10 4 dPa·s of 1,320°C or lower, containing, indicated by % by mass on the basis of oxides: SiO 2 58.5 to 67.5, Al 2 O 3 18 to 24, B 2 O 3 0 to 1.7, MgO 6.0 to 8.5, CaO 3.0 to 8.5, SrO 0.5 to 7.5, BaO 0 to 2.5, and ZrO 2 0 to 4.0, containing 0 to 0.35% by mass of Cl, 0.01 to 0.15% by mass of F, and 0.01 to 0.3% by mass of SnO 2 , and having a ²-OH value of the glass of from 0.15 to 0.60 mm -1 , in which (MgO/40.3)+(CaO/56.1)+(SrO/103.6)+(BaO/153.3) is from 0.27 to 0.35, (MgO/40.3)/((MgO/40.3)+(CaO/56.1)+(SrO/103.6)+(BaO/153.3)) is 0.40 or more, (MgO/40.3)/((MgO/40.3)+(CaO/56.1)) is 0.40 or more, and (MgO/40.3)/((MgO/40.3)+(SrO/103.6)) is 0.60 or more.</p> |
