Alkali-free glass
AssigneeAGC Inc.
InventorsHirofumi TOKUNAGA, Kazutaka ONO
Life of this patent
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Abstract
An alkali free glass having an average coefficient of thermal expansion at 50 to 350° C. of 30×10−7 to 43×10−7/° C., a strain point of 650 to 725° C., a temperature T4 at which a viscosity reaches 104 dPa·s of 1,290° C. or lower, and a temperature T2 at which the viscosity reaches 102 dPa·s of 1,680° C. or lower, and including, as represented by mol % based on oxides: 62 to 67% of SiO2, 8 to 13% of MgO, 6 to 12% of CaO, 0.5 to 4% of SrO, and 0 to 0.5% of BaO, wherein MgO+CaO+SrO+BaO is 18 to 22%, and MgO/CaO is 0.8 or more, and the alkali free glass has a value expressed by the following Expression (I) of 4.6 or less: (7.87[A2O3]-8.5[B2O3]+11.35[MgO]+7.09[CaO]+5.52[SrO]−1.45[BaO])/[SiO2] Expression (I).
Claims17
An alkali free glass having an average coefficient of thermal expansion at 50 to 350° C. of 30×10−7 to 43×10−7/° C., a strain point of 650 to 725° C., a temperature T4 at which a viscosity reaches 104 dPa·s of 1,290° C. or lower, and a temperature T2 at which the viscosity reaches 102 dPa·s of 1,680° C. or lower, and
- comprising, as represented by mol % based on oxides:
- 62 to 67% of SiO2,
- 8 to 13% of MgO,
- 6 to 12% of CaO,
- 0.5 to 4% of SrO, and
- 0 to 0.5% of BaO,
- wherein MgO+CaO+SrO+BaO is 18 to 22%, and MgO/CaO is 0.8 or more, and
- the alkali free glass has a value expressed by the following Expression (I) of 4.6 or less:
- (7.87[Al2O3]−8.5[B2O3]+11.35[MgO]+7.09[CaO]+5.52[SrO]−1.45[BaO])/[SiO2] Expression (I).
Dependencies are inferred from the claim text.