US 12,448,320 B2
Alkali-free glass
Hirofumi Tokunaga, Tokyo (JP); and Kazutaka Ono, Tokyo (JP)
Assigned to AGC Inc., Tokyo (JP)
Filed by AGC Inc., Tokyo (JP)
Filed on Aug. 6, 2021, as Appl. No. 17/396,247.
Application 17/396,247 is a continuation of application No. PCT/JP2020/004850, filed on Feb. 7, 2020.
Claims priority of application No. 2019-020257 (JP), filed on Feb. 7, 2019; application No. 2019-051570 (JP), filed on Mar. 19, 2019; application No. 2019-141422 (JP), filed on Jul. 31, 2019; application No. 2019-186805 (JP), filed on Oct. 10, 2019; and application No. 2020-017692 (JP), filed on Feb. 5, 2020.
Prior Publication US 2021/0387897 A1, Dec. 16, 2021
This patent is subject to a terminal disclaimer.
Int. Cl. C03C 3/091 (2006.01); C03C 3/087 (2006.01)
CPC C03C 3/091 (2013.01) [C03C 3/087 (2013.01)] 55 Claims
 
1. An alkali-free glass, comprising, in mol % in terms of oxides:
SiO2: 63-75%;
Al2O3: 10-16%;
B2O3: 1.7-5%;
MgO: 0.1-15%;
CaO: 0.1-12%;
SrO: 0-8%; and
BaO: 1.6-6%,
wherein:
[MgO]/[CaO] is larger than 1.5;
a value of Formula (A) is 82.5 or larger, Formula (A) being 1.131[SiO2]+1.933[Al2O3]+0.362[B2O3]+2.049[MgO]+1.751[CaO]+1.471[SrO]+1.039[BaO]−48.25;
a value of Formula (B) is 690 or larger and 800 or smaller, Formula (B) being 35.59[SiO2]+37.34[Al2O3]+24.59[B2O3]+31.13[MgO]+31.26[CaO]+30.78[SrO]+31.98[BaO]−2761;
a value of Formula (C) is 100 or smaller, Formula (C) being −9.01[SiO2]+36.36[Al2O3]+5.7[B2O3]+5.13[MgO]+17.25[CaO]+7.65[SrO]+10.58[BaO];
a value of Formula (D) is 20 or smaller, Formula (D) being −0.731[SiO2]+1.461[Al2O3]−0.157[B2O3]+1.904[MgO]+3.36[CaO]+3.411[SrO]+1.723[BaO]+(−3.318[MgO][CaO]−1.675[MgO][SrO]+1.757[MgO][BaO]+4.72[CaO][SrO]+2.094[CaO][BaO]+1.086[SrO][BaO])/([MgO]+[CaO]+[SrO]+[BaO]); and
the alkali-free glass has a Young's modulus of 83 GPa or larger and a surface devitrification viscosity ηc of 104.2 dPa·s or higher.