# US 12,006,252 B2 · Chemically strengthened glass with a film and method for measuring surface stress of chemically strengthened glass

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- Number: US 12,006,252 B2
- Document ID: US12006252B2
- Status: Granted
- Kind: B2
- Application number: 17/469,139
- Filed: 2021-09-08
- Published: 2022-03-10
- Granted: 2024-06-11
- Earliest claimed: 2020-09-09
- Assignees: AGC Inc.
- Applicants: AGC Inc.
- Inventors: Seiki Ohara; Shunji Wachi; Hironobu Sato
- Web page: https://patentgrep.com/patent/US12006252B2

## CPC

- C03C 3/095: containing rare earths
- C03C 21/002: {to perform ion-exchange between alkali ions (C03C21/005 takes precedence)}
- C03C 17/28: with organic material (C03C17/34, C03C17/44 take precedence)
- C03C 17/30: with silicon-containing compounds
- C03C 17/32: with synthetic or natural resins (C03C17/30 takes precedence)
- C03C 17/42: at least one coating of an organic material and at least one non-metal coating
- G01L 1/24: by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis {using infrared, visible light, ultraviolet}
- C03C 2217/732: made of a single layer
- C03C 2217/734: comprising an alternation of high and low refractive indexes
- C03C 2218/151: by vacuum evaporation
- 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
- G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G)

## Abstract

The present invention relates to a chemically strengthened glass with a film, including: a chemically strengthened glass having a pair of main surfaces opposing each other; and a film formed on at least one of the main surfaces of the chemically strengthened glass, in which the chemically strengthened glass has two or less interference fringes observed under stress measurement utilizing surface propagation light having a wavelength of 365 nm, and the film has a refractive index lower than a refractive index of the chemically strengthened glass.

## Claims

### Claim 1

A chemically strengthened glass with a film, comprising:
a chemically strengthened glass having a pair of main surfaces opposing each other; and
a film formed on at least one of the main surfaces of the chemically strengthened glass,
the chemically strengthened glass having a base composition comprising, in mole percentage on an oxide basis:
68.5-80% of SiO2;
8-20% of Al2O3;
0-10% of B2O3;
10.6-14% of Li2O;
2-12% of Na2O;
0-10% of K2O;
0-10% of a total content (MgO+CaO+SrO+BaO) of MgO, CaO, SrO, and BaO;
0-5% of a total content (ZrO2+TiO2) of ZrO2 and TiO2; and
7-20% of a total content (Li2O+Na2O+K2O) of Li2O, Na2O, and, K2O,
wherein the chemically strengthened glass has two or less interference fringes observed under stress measurement utilizing surface propagation light having a wavelength of 365 nm, and
the film has a refractive index lower than a refractive index of the chemically strengthened glass.

### Claim 2 (depends on 1)

The chemically strengthened glass with a film according to claim 1, wherein a difference between the refractive index of the film and the refractive index of the chemically strengthened glass is in a range of 0.02 to 0.30.

### Claim 3 (depends on 1)

The chemically strengthened glass with a film according to claim 1, Wherein a stress depth of a deep layer of the chemically strengthened glass is 0.1×t or more, where t is a thickness of the chemically strengthened glass.

### Claim 4 (depends on 1)

The chemically strengthened glass with a film according to claim 1, wherein the film has a thickness in a range of 2 nm to 50 nm.

### Claim 5 (depends on 1)

The chemically strengthened glass with a film according to claim 1, wherein the film comprises a fluorine-based organic compound.

### Claim 6 (depends on 1)

The chemically strengthened glass with a film according to claim 1, wherein a surface stress depth formed by potassium ions is 4 μm or less.

### Claim 7 (depends on 1)

The chemically strengthened glass with a film according to claim 1, wherein a surface stress depth formed by potassium ions is 2.9 μm or less.

### Claim 8 (depends on 1)

The chemically strengthened glass with a film according to claim 1, wherein the content of Li2O is 5% or more and 12% or less.

### Claim 9 (depends on 1)

The chemically strengthened glass with a film according to claim 1, wherein the total content (MgO+CaO+SrO+BaO) of MgO, CaO, SrO, and BaO is 0% or more and 5% or less.

### Claim 10 (depends on 1)

A surface stress measuring method for a chemically strengthened glass having a pair of main surfaces opposing each other, the method comprising:
obtaining a chemically strengthened glass with a film according to claim 1, by forming a film having a refractive index lower than a refractive index of the chemically strengthened glass on at least one of the main surfaces of the chemically strengthened glass; and
measuring a surface compressive stress of the chemically strengthened glass by performing stress measurement utilizing surface propagation light on the chemically strengthened glass with a film,
wherein the chemically strengthened glass has two or less interference fringes observed under stress measurement utilizing surface propagation light having a wavelength of 365 nm.

### Claim 11 (depends on 10)

The surface stress measuring method for a chemically strengthened glass according to claim 10, wherein the surface propagation light to be applied to the chemically strengthened glass with a film has a wavelength of 650 nn or less.