Non-alkali glass substrate

摘要

The present invention relates to a non-alkali glass substrate, having a strain point of 685° C. or higher and 750° C. or lower, an average thermal expansion coefficient at 50 to 350° C. of from 35×10−7 to 43×10−7/° C., a specific gravity of from 2.50 to 2.80, a photoelastic constant of 25 nm/MPa/cm or more and less than 29 nm/MPa/cm, and a temperature (T4) at which viscosity reaches 104 dPa·s of 1,250° C. or higher and lower than 1,350° C., and having a prescribed composition.

主权项

1. A non-alkali glass substrate, having a strain point of 685° C. or higher and 750° C. or lower, an average thermal expansion coefficient at 50 to 350° C. of from 35×10−7 to 43×10−7/° C., a specific gravity of from 2.50 to 2.80, a photoelastic constant of 25 nm/MPa/cm or more and less than 29 nm/MPa/cm, and a temperature (T4) at which viscosity reaches 104 dPa·s of 1,250° C. or higher and lower than 1,350° C., and comprising, indicated by mol % on the basis of oxides,
63% or more and 68% or less of SiO2, 12.2% or more and 14% or less of Al2O3, 0.5% or more and less than 3% of B2O3, 6.5% or more and 13% or less of MgO, 0% or more and less than 4% of CaO, 0% or more and 9% or less of SrO, and 0% or more and 10% or less of BaO, wherein
MgO+CaO+SrO+BaO is from 15 to 20%, andSrO+BaO is from 4 to 10%.