# US 11,028,013 B2 · Chemically strengthened glass and method for producing the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,028,013 B2 - Document ID: US11028013B2 - Status: Granted - Kind: B2 - Application number: 15/896,639 - Filed: 2018-02-14 - Published: 2018-08-16 - Granted: 2021-06-08 - Earliest claimed: 2017-02-15 - Assignees: AGC Inc. - Applicants: AGC Inc. - Inventors: Masao Ozeki; Shusaku Akiba; Izuru Kashima - Web page: https://patentgrep.com/patent/US11028013B2 ## CPC - C03C 21/002: {to perform ion-exchange between alkali ions (C03C21/005 takes precedence)} - C03C 3/085: containing an oxide of a divalent metal - C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS ## Abstract A chemically strengthened glass has a compressive stress layer formed in a glass surface layer by ion exchange. The compressive stress layer includes at least two types of stress patterns of a stress pattern A close to a glass surface and a stress pattern B on an inner side of the glass. In the stress pattern A, compressive stress increases as going inward from the glass surface. In the stress pattern B, compressive stress decreases as going inward from the glass surface. Depth of compressive stress layer in the stress pattern B is 90 μm or more from the glass surface. Compressive stress α MPa of the glass surface in the stress pattern A and compressive stress β MPa at a point where the stress pattern A and the stress pattern B cross each other satisfy a relation of β>α. ## Claims ### Claim 1 A chemically strengthened glass having a compressive stress layer formed in a glass surface layer by ion exchange, wherein the compressive stress layer includes at least two types of stress patterns of a stress pattern A close to a glass surface and a stress pattern B on an inner side of the glass, in the stress pattern A, compressive stress increases as going inward from the glass surface, in the stress pattern B, compressive stress decreases as going inward from the glass surface, depth of compressive stress layer in the stress pattern B is 90 μm or more from the glass surface, and compressive stress α MPa of the glass surface in the stress pattern A and compressive stress β MPa at a point where the stress pattern A and the stress pattern B cross each other satisfy a relation of β>α, and wherein the compressive stress layer further includes a stress pattern C on an inner side of the glass from the stress pattern B, and when the stress pattern C is approximated as a linear function, a slope i MPa/μm of compressive stress thereof satisfies −8≤i<0. ### Claim 2 (depends on 1) The chemically strengthened glass according to claim 1, wherein a value obtained by dividing the compressive stress α MPa by the compressive stress β MPa is less than 0.9. ### Claim 3 (depends on 1) The chemically strengthened glass according to claim 1, wherein the compressive stress layer includes the two types of stress patterns of the stress pattern A and the stress pattern B, and depth of compressive stress layer in the stress pattern A is more than 10 μm. ### Claim 4 (depends on 1) The chemically strengthened glass according to claim 1, wherein a value of compressive stress of 250 MPa or more at a position 15 μm deep from the glass surface thereof is 250 MPa or more. ### Claim 5 (depends on 1) A chemically strengthened glass according to claim 1, which has a thickness of 0.7 mm or less. ### Claim 6 (depends on 1) A method for producing a chemically strengthened glass according to claim 1, in which a compressive stress layer is formed in a glass surface layer by an ion exchange treatment of replacing alkali metal ions a in the glass with alkali metal ions b having larger ion radius than the alkali metal ions a, the method comprising sequentially for the ion exchange treatment: a first step of bringing the glass into contact with a first salt which contains the alkali metal ions a and the alkali metal ions b and in which a ratio of a molar amount of the alkali metal ions b to a total of a molar amount of the alkali metal ions a and the molar amount of the alkali metal ions b is X1′%; a second step of bringing the glass into contact with a second salt in which the ratio is X2′%; and a third step of bringing the glass into contact with a third salt in which the ratio is X3′%; wherein: the ratios X1′%, X2′% and X3′% satisfy a relation of X3′