US 12,454,480 B2
Crystallized glass, chemically strengthened glass, and production method therefor
Hitomi Furuta, Tokyo (JP); Takanori Fukushi, Tokyo (JP); Qing Li, Tokyo (JP); and Yusuke Arai, Tokyo (JP)
Assigned to AGC Inc., Tokyo (JP)
Filed by AGC Inc., Tokyo (JP)
Filed on Sep. 23, 2021, as Appl. No. 17/448,570.
Application 17/448,570 is a continuation of application No. PCT/JP2020/011304, filed on Mar. 13, 2020.
Claims priority of application No. 2019-072736 (JP), filed on Apr. 5, 2019.
Prior Publication US 2022/0002189 A1, Jan. 6, 2022
Int. Cl. B32B 9/00 (2006.01); C03C 10/00 (2006.01)
CPC C03C 10/0054 (2013.01) [C03C 2203/50 (2013.01)] 15 Claims
OG exemplary drawing
 
1. A glass ceramic, comprising:
a glass ceramic having a three-dimensional shape and comprising a plurality of R-shapes including a smallest R-shape having an average radius of curvature of 5.0×102 mm or less and a largest R-shape having an average radius of curvature is 1.0×103 mm or more,
wherein the glass ceramic has a composition comprising, in mass % in terms of oxides, 58-74% of SiO2 and greater than 0% of SnO2, the glass ceramic has a haze value of 1.0% or less corresponding to a thickness of 0.8 mm in the largest R-shape and a maximum value of 20 nm/mm or less for retardations measured using a birefringence measuring instrument by perpendicularly irradiating one or more points on a circular arc of each R-shape with a light having a wavelength of 543 nm, and no retardation measurement is performed in a case that an angle formed by a tangential line of a curved surface of a central portion of a measurement sample and a tangential line of a measurement target surface is 90° or more.