# US 2016/0355432 A1 · Glass for chemical strengthening, chemically strengthened glass, and method for producing chemically strengthened glass

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- Number: US 2016/0355432 A1
- Document ID: US20160355432A1
- Status: Published application
- Kind: A1
- Application number: 15/179,433
- Filed: 2016-06-10
- Published: 2016-12-08
- Earliest claimed: 2013-12-13
- Assignees: Asahi Glass Company, Limited
- Applicants: Asahi Glass Company, Limited
- Inventors: Junichiro KASE
- Web page: https://patentgrep.com/patent/US20160355432A1

## CPC

- C03C 3/087: containing calcium oxide, e.g. common sheet or container glass
- C03C 3/085: containing an oxide of a divalent metal
- C03C 4/18: for ion-sensitive glass
- C03C 21/002: {to perform ion-exchange between alkali ions (C03C21/005 takes precedence)}
- C03C 2204/00: Glasses, glazes or enamels with special properties
- 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 glass for chemical strengthening is a glass sheet containing, as expressed by mass percentage based on oxides, 60 to 75% of SiO2, 3 to 12% of Al2O3, 2 to 10% of MgO, 0 to 10% of CaO, 0 to 3% of SrO, 0 to 3% of BaO, 10 to 18% of Na2O, 0 to 8% of K2O, 0 to 3% of ZrO2, 0 to 0.3% of TiO2, 0.005 to 0.2% of Fe2O3, and 0.02 to 0.4% of SO3. The glass has a sheet thickness of 0.2 mm or more and 1.2 mm or less. A value of β-OH measured without polishing both front and back surfaces of the glass sheet is lower than a value of β-OH measured after polishing surface layers of both the front and back surfaces of the glass sheet by 50 μm or more each.

## Claims

### Claim 1

A glass for chemical strengthening that is a glass sheet comprising, as expressed by mass percentage based on oxides, 60 to 75% of SiO2, 3 to 12% of Al2O3, 2 to 10% of MgO, 0 to 10% of CaO, 0 to 3% of SrO, 0 to 3% of BaO, 10 to 18% of Na2O, 0 to 8% of K2O, 0 to 3% of ZrO2, 0 to 0.3% of TiO2, 0.005 to 0.2% of Fe2O3, and 0.02 to 0.4% of SO3, and having a sheet thickness of 0.2 mm or more and 1.2 mm or less, wherein a value of β-OH measured without polishing both front and back surfaces of the glass sheet is lower than a value of β-OH measured after polishing surface layers of both the front and back surfaces of the glass sheet by 50 μm or more each.

### Claim 2 (depends on 1)

The glass for chemical strengthening according to claim 1, wherein the glass sheet is formed according to a float process.

### Claim 3 (depends on 2)

The glass for chemical strengthening according to claim 2, from which the surface layers of both the front and back surfaces of the glass sheet has not been polished away after being formed according to the float process.

### Claim 4 (depends on 1)

The glass for chemical strengthening according to claim 1, wherein a difference between the value of β-OH measured without polishing both the front and back surfaces of the glass sheet and the value of β-OH measured after polishing the surface layers of both the front and back surfaces of the glass sheet by 50 μm or more each is 0.003 mm−1 or more.

### Claim 5 (depends on 1)

A chemically strengthened glass obtained by chemically strengthening the glass for chemical strengthening of claim 1.

### Claim 6 (depends on 5)

The chemically strengthened glass according to claim 5, having a surface compressive stress of 600 MPa or more and a depth of compressive stress of 6 μm or more and 30 μm or less.

### Claim 7 (depends on 5)

The chemically strengthened glass according to claim 5, having a surface compressive stress of 700 MPa or more and a depth of compressive stress of 8 μm or more and 20 μm or less.

### Claim 8 (depends on 1)

A method for producing a chemically strengthened glass, comprising a chemical strengthening step of subjecting the glass for chemical strengthening of claim 1 to an ion-exchange treatment.

### Claim 9

A glass that is a glass sheet comprising, as expressed by mass percentage based on oxides, 60 to 75% of SiO2, 3 to 12% of Al2O3, 2 to 10% of MgO, 0 to 10% of CaO, 0 to 3% of SrO, 0 to 3% of BaO, 10 to 18% of Na2O, 0 to 8% of K2O, 0 to 3% of ZrO2, 0 to 0.3% of TiO2, 0.005 to 0.2% of Fe2O3, and 0.02 to 0.4% of SO3, and having a sheet thickness of 0.2 mm or more and 1.2 mm or less, wherein a value of β-OH measured without polishing both front and back surfaces of the glass sheet is lower than a value of β-OH measured after polishing surface layers of both the front and back surfaces of the glass sheet by 50 βm or more each.

### Claim 10 (depends on 9)

The glass according to claim 9, wherein, after being formed according to a float process, the surface layers of both the front and back surfaces of the glass sheet has not been polished away.

### Claim 11 (depends on 9)

The glass according to claim 9, wherein a difference between the value of β-OH measured without polishing both the front and back surfaces of the glass sheet and the value of β-OH measured after polishing the surface layers of both the front and back surfaces of the glass sheet by 50 μm or more each is 0.003 mm−1 or more.

### Claim 12 (depends on 9)

The glass according to claim 9, wherein the glass sheet is applicable to a chemical strengthening treatment.

### Claim 13 (depends on 12)

A chemically strengthened glass obtained by chemically strengthening the glass of claim 12.