# US 2016/0355431 A1 · Glass for chemical strengthening and chemically strengthened glass

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- Number: US 2016/0355431 A1
- Document ID: US20160355431A1
- Status: Published application
- Kind: A1
- Application number: 15/179,273
- Filed: 2016-06-10
- Published: 2016-12-08
- Earliest claimed: 2013-12-13
- Assignees: Asahi Glass Company, Limited
- Applicants: Asahi Glass Company, Limited
- Inventors: Shusaku Akiba; Akio Koike; Junichiro Kase; Shuji Yamazaki
- Web page: https://patentgrep.com/patent/US20160355431A1

## CPC

- C03C 3/087: containing calcium oxide, e.g. common sheet or container glass
- C03C 21/002: {to perform ion-exchange between alkali ions (C03C21/005 takes precedence)}
- 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 contains, as expressed by mass percentage based on oxides, 60% to 75% of SiO2, 3% to 9% of Al2O3, 2% to 10% of MgO, 3% to 10% of CaO, 10% to 18% of Na2O, at most 4% of K2O, 0% to 3% of ZrO2, 0% to 0.3% of TiO2, and 0.02% to 0.4% of SO3. It has a temperature T2 at which a viscosity of a glass melt is 100 dPa·sec of 1530° C. or lower. In a chemically strengthened main surface thereof, it has a depth of a compressive stress layer of 8 μm or more and a surface compressive stress of 500 MPa or more.

## Claims

### Claim 1

A chemically strengthened glass
comprising, as expressed by mass percentage based on oxides:
60% to 75% of SiO2,
3% to 9% of Al2O3,
2% to 10% of MgO,
3% to 10% of CaO,
10% to 18% of Na2O,
at most 4% of K2O,
0% to 3% of ZrO2,
0% to 0.3% of TiO2, and
0.02% to 0.4% of SO3;
having a temperature T2 at which a viscosity of a glass melt is 100 dPa·sec of 1530° C. or lower; and
in a chemically strengthened main surface thereof, having a depth of a compressive stress layer of 8 μm or more and a surface compressive stress of 500 MPa or more.

### Claim 2 (depends on 1)

The chemically strengthened glass according to claim 1, having a thickness falling within a range of 0.1 mm to 5 mm.

### Claim 3 (depends on 1)

The chemically strengthened glass according to claim 1, chemically strengthened in all edge surfaces thereof.

### Claim 4 (depends on 1)

The chemically strengthened glass according to claim 1, wherein the depth of the compressive stress layer is 25 μm or less.

### Claim 5 (depends on 1)

The chemically strengthened glass according to claim 1, produced according to a float process.

### Claim 6 (depends on 1)

The chemically strengthened glass according to claim 1, wherein an Sn component exists in at least one surface of glass surfaces.

### Claim 7

A glass
comprising, as expressed by mass percentage based on oxides:
60% to 75% of SiO2,
3% to 9% of Al2O3,
2% to 10% of MgO,
3% to 10% of CaO,
10% to 18% of Na2O,
at most 4% of K2O,
0% to 3% of ZrO2,
0% to 0.3% of TiO2, and
0.02% to 0.4% of SO3; and
having a temperature T2 at which a viscosity of a glass melt is 100 dPa·sec of 1530° C. or lower.

### Claim 8 (depends on 7)

The glass according to claim 7, which is a glass applicable to a chemical strengthening treatment, having a depth of a compressive stress layer of 8 μm or more and a surface compressive stress of 500 MPa or more, in a chemically strengthened main surface thereof when being processed for the chemical strengthening treatment.

### Claim 9 (depends on 7)

The glass according to claim 7, wherein when a refractive index at a room temperature of the glass is referred to as R1 and when a refractive index at the room temperature of the glass, after kept at a temperature higher by about 100° C. than a glass transition point for 10 minutes and then annealed to the room temperature at a rate of 1° C./min, is referred to as R2, R2-R1 is 0.0003 or more and 0.0012 or less.

### Claim 10 (depends on 7)

The glass according to claim 7, produced according to a float process.

### Claim 11

A glass for chemical strengthening
comprising, as expressed by mass percentage based on oxides:
60% to 75% of SiO2,
3% to 9% of Al2O3,
2% to 10% of MgO,
3% to 10% of CaO,
10% to 18% of Na2O,
at most 4% of K2O,
0% to 3% of ZrO2,
0% to 0.3% of TiO2, and
0.02% to 0.4% of SO3; and
having a temperature T2 at which a viscosity of a glass melt is 100 dPa·sec of 1530° C. or lower.

### Claim 12 (depends on 11)

The glass for chemical strengthening according to claim 11, wherein when a refractive index at a room temperature of the glass for chemical strengthening is referred to as R1 and when a refractive index at the room temperature of the glass for chemical strengthening, after kept at a temperature higher by about 100° C. than a glass transition point for 10 minutes and then annealed to the room temperature at a rate of 1° C./min, is referred to as R2, R2-R1 is 0.0003 or more and 0.0012 or less.

### Claim 13 (depends on 11)

The glass for chemical strengthening according to claim 11, produced according to a float process.