# US 12,006,255 B2 · Lithium containing aluminosilicate glass with low expansion after chemical toughening

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 12,006,255 B2
- Document ID: US12006255B2
- Status: Granted
- Kind: B2
- Application number: 16/552,326
- Filed: 2019-08-27
- Published: 2019-12-19
- Granted: 2024-06-11
- Earliest claimed: 2017-02-27
- Assignees: SCHOTT Glass Technologies (Suzhou) Co. Ltd.
- Applicants: SCHOTT Glass Technologies (Suzhou) Co. Ltd.
- Inventors: Junming Xue; Feng He; Jose Zimmer; Ning Da
- Web page: https://patentgrep.com/patent/US12006255B2

## CPC

- C03C 3/083: containing aluminium oxide or an iron compound
- C03C 3/093: containing zinc or zirconium
- C03C 3/078: containing an oxide of a divalent metal, e.g. an oxide of zinc
- C03C 3/085: containing an oxide of a divalent metal
- C03C 3/089: containing boron
- C03C 3/097: containing phosphorus, niobium or tantalum
- C03C 21/002: {to perform ion-exchange between alkali ions (C03C21/005 takes precedence)}
- C03C 2203/50: After-treatment
- 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 toughenable or toughened glass has, before chemical toughening, a thickness t of at most 1100 μm. The glass comprises the following components: 45-75 mol-% SiO2; 10-25 mol-% Al2O3; >1-11 mol-% Li2O; 0-15 mol-% P2O5; 0-8 mol-% B2O3; and 0-5 mol-% TiO2. The average number of bridging oxygen per polyhedron (BO) calculated as 2*4−2*(cmol(O)/(cmol(Si)+cmol(Al)+cmol(B)+cmol(P)+cmol(Ti))) is higher than 3.55. Upon chemical toughening, the linear dimension variation in the unit of percentage (V1) is so low that the overall geometry variation (OGV) calculated as (DoL/t)/V1 is higher than 0.8. DoL is the total depth of all ion-exchange layers on one side of the glass and DoL is more than 1 μm, when the glass is chemically toughened with NaNO3 only, KNO3 only or with both KNO3 and NaNO3.

## Claims

### Claim 1

A chemically toughenable or toughened glass having before chemical toughening a thickness t of less than or equal to 500 μm, the glass comprising the following components in mol-%:
SiO2 45-75;
Al2O3 12-25;
Li2O >1-11;
P2O5 0-15;
B2O3 0-8;
TiO2 0-5; and
Na2O in an amount of at least 3 mol-%;
wherein an average number of bridging oxygen per polyhedron (BO) calculated as 2*4−2*(cmol(O)/(cmol(Si)+cmol(Al)+cmol(B)+cmol(P)+cmol(Ti))) is higher than 3.55 and wherein upon chemical toughening a linear dimension variation in the unit of percentage V1 is so low that an overall geometry variation OGV calculated as (DoL/O/V1 is higher than 0.8, wherein DoL is a total depth of all ion-exchange layers on one side of the glass and wherein DoL is from >3 μm to <0.5*t when the glass is chemically toughened with NaNO3 only, KNO3 only, or with both KNO3 and NaNO3, wherein a molar ratio of Li2O/(Li2O+Na2O+K2O) is larger than 0.20.

### Claim 2 (depends on 1)

The glass of claim 1, wherein the glass has a Young's modulus of from 60 GPa to 120 GPa.

### Claim 3 (depends on 1)

The glass of claim 1, wherein a geometry variation after chemical toughening GVACT calculated as GVACT=BO*Young's modulus is from >250 GPa to <500 GPa.

### Claim 4 (depends on 1)

The glass of claim 1, wherein BO is from >3.6 to 4.0.

### Claim 5 (depends on 1)

The glass of claim 1, wherein OGV is from >1.0 to <10.0.

### Claim 6 (depends on 1)

The glass of claim 1, wherein the thickness t of the glass before chemical toughening is >6 μm.

### Claim 7 (depends on 1)

The glass of claim 1, wherein the glass has at least one surface with a roughness Ra of less than 5 nm.

### Claim 8 (depends on 1)

The glass of claim 1, wherein a temperature difference ΔT between a working temperature T4 and a maximum crystallization temperature TOEG of the glass is higher than 50 K.

### Claim 9 (depends on 1)

The glass of claim 1, wherein the glass has a coefficient of thermal expansion CTE of from 3 ppm/K to 12 ppm/K in a temperature range of from 20° C. to 300° C.

### Claim 10 (depends on 1)

The glass of claim 1, wherein a surface compressive stress CS of the glass after chemical toughening is from >0 MPa to <1500 MPa.

### Claim 11 (depends on 1)

The glass of claim 1, wherein the glass comprises an outer ion exchange layer and an inner ion exchange layer after chemical toughening, wherein the inner ion exchange layer is positioned between the outer ion exchange layer and a bulk glass, wherein the bulk glass is the part of the glass that has not been ion exchanged.

### Claim 12 (depends on 11)

The glass of claim 11, wherein a molar concentration of Na+ in the inner ion exchange layer is higher than a molar concentration of Na+ in the outer ion exchange layer.

### Claim 13 (depends on 11)

The glass of claim 11, wherein a molar concentration of K+ in the inner ion exchange layer is lower than a molar concentration of K+in the outer ion exchange layer.

### Claim 14 (depends on 11)

The glass of claim 11, wherein a molar concentration of K+ in the inner ion exchange layer is lower than a molar concentration of Na+in the inner ion exchange layer.

### Claim 15 (depends on 11)

The glass of claim 11, wherein a molar concentration of K+ in the outer ion exchange layer is higher than a molar concentration of Na+ in the outer ion exchange layer.

### Claim 16 (depends on 11)

The glass of claim 11, wherein a thickness of the inner ion exchange layer is at least as high as a thickness of the outer ion exchange layer.

### Claim 17 (depends on 1)

The glass of claim 1, wherein the glass comprises at least one of the following:
a content of ZrO2 from 0 to 5 mol-%;
a content of alkali metal oxides R2O from 10 to 30 mol-%;
a content of Na2O from 3 to 15 mol-%;
a content of K2O from 0 to 5 mol-%;
a content of the sum of Li2O and Na2O from 10 to 25 mol-%;
a content of MgO from 0 to 5 mol-%;
a content of ZnO from 0 to 5 mol-%;
a content of the sum of MgO and ZnO from 0 to 10 mol-%;
a content of at least one of SnO2, SbO2, CeO2 or Fe2O3 from 0 to 3 mol-%; or
a content of Al2O3 from >12 to 22 mol-%.

### Claim 18 (depends on 1)

The glass of claim 1, wherein a molar ratio of Na2O/(Na2O+K2O) is from >0.5 to 1.0.

### Claim 19 (depends on 1)

The glass of claim 1, wherein a molar ratio of Li2O/(Li2O+Na2O+K2O) is from >0.1 to 0.6.

### Claim 20 (depends on 1)

The glass of claim 1, wherein the glass comprises the following components in mol-%:
Li2O >1-<8; and
K2O 0-5.

### Claim 21 (depends on 1)

The glass of claim 1, wherein the glass comprises the following components in mol-%:
SiO2 >63-75;
Al2O3 12-25;
Li2O >2.5-<8;
P2O5 0-10;
B2O3 1-5; and
K2O >0.5-5.

### Claim 22

A method for producing a glass, the method comprising the steps of:
a) providing a composition;
b) melting the composition;
c) producing the glass from the melted composition; and
d) chemically toughening the glass, the glass having before chemical toughening a thickness t of less than or equal to 500 μm, the glass comprising the following components in mol-%:
SiO2 45-75;
Al2O3 12-25;
Li2O >1-11;
P2O5 0-15;
B2O3 0-8;
TiO2 0-5; and
Na2O in an amount of at least 3 mol-%;
wherein an average number of bridging oxygen per polyhedron BO calculated as 2*4−2*(cmol(O)/(cmol(Si)+cmol(Al)+cmol(B)+cmol(P)+cmol(Ti))) is higher than 3.55 and wherein upon chemical toughening a linear dimension variation in the unit of percentage V1 is so low that an overall geometry variation OGV calculated as (DoL/t)/V1 is higher than 0.8, wherein DoL is a total depth of all ion-exchange layers on one side of the glass and wherein DoL is from >3 μm to <0.5*t, when the glass is chemically toughened with NaNO3 only, KNO3 only, or with both KNO3 and NaNO3, wherein a molar ratio of Li2O/(Li2O+Na2O+K2O) is larger than 0.20.

### Claim 23 (depends on 1)

The glass of claim 1, wherein the molar ratio of Li2O/(Li2O+Na2O+K2O) is larger than 0.21.