Method for tempering glass plate, and tempered glass plate

Patent metadata

Field	Value
Publication number	US-10654742-B2
Application number	US-201816047660-A
Country	US
Kind code	B2
Filing date	Jul 27, 2018
Priority date	Feb 26, 2016
Publication date	May 19, 2020
Grant date	May 19, 2020

Abstract

To provide a method for tempering glass to obtain tempered glass having high surface quality and a deep compression stress layer. The present invention relates to a method for tempering a glass plate comprising a preparation step of preparing a glass plate having a surface temperature of at most the strain point, an internal heating step of heating the internal temperature of the glass plate to be at least the annealing point, while maintaining the surface temperature of the glass plate within 10 minutes, or to be at most the strain point, and a cooling step of cooling the glass plate.

First claim

What is claimed is:

1. A tempered glass plate made of glass with a single matrix composition and having a first main surface and a second main surface opposed to each other,
wherein the tempered glass plate has a compressive stress layer at its surface, and
wherein in the distribution of stress remaining in a cross section passing through the center of the first main surface and being perpendicular to the first main surface, a depth from the first main surface where the compressive stress component in a direction parallel to the first main surface becomes zero, is at least 22% of a plate thickness of the tempered glass plate.

2. The tempered glass plate according to claim 1 , which has at least one of a first region and a second region in a range from the first main surface to a position where the above compressive stress component becomes zero, wherein
the first region is a region where an absolute value of a change rate of the stress distribution in the plate thickness direction of the tempered glass plate becomes constant, and
the second region is a region where the absolute value decreases towards the first main surface.

3. The tempered glass plate according to claim 1 , wherein in the stress distribution, the absolute value of the change rate in the plate thickness direction of the tempered glass plate becomes maximum between a position where the compressive stress component becomes zero and the first main surface, and then decreases towards the first main surface.

4. The tempered glass plate according to claim 1 , wherein in the stress distribution, the compressive stress component at the first main surface is less than 1.6 times a tensile stress component at a center of the cross-section.

5. The tempered glass plate according to claim 1 , wherein the compressive stress component at the first main surface is from 5 to 85 MPa.

6. The tempered glass plate according to claim 1 , which has a compressive stress layer formed by ion exchange at least at the first main surface.

7. The tempered glass plate according to claim 6 , wherein the compressive stress component at the first main surface is from 100 to 2,000 MPa.

8. The tempered glass plate according to claim 1 , wherein the plate thickness is from 0.5 to 25 mm.

9. The tempered glass plate according to claim 6 , wherein the tempered glass plate is made by the method comprising:
maintaining a surface temperature of a glass plate made of a glass with a single matrix composition at at most a strain point of the glass;
internally heating the glass plate such that the internal temperature of the glass plate to be at least an annealing point of the glass, while maintaining the surface temperature of the glass plate to be higher than the strain point and at most the annealing point within 10 minutes, or to be at most the strain point; and
cooling the glass plate.

Assignees

• Agc Inc

Inventors

• Saito Isao
• Kato Yasumasa

Classifications

• C03B29/025

  Glass sheets · CPC title

• C03C21/002

  to perform ion-exchange between alkali ions (C03C21/005 takes precedence) · CPC title

• C03B27/012 Primary

  by heat treatment, e.g. for crystallisation; Heat treatment of glass products before tempering by cooling (C03B27/008, C03B27/016 take precedence) · CPC title

• C03B29/08

  Glass sheets · CPC title

• C03B27/0413 Primary

  Stresses, e.g. patterns, values or formulae for flat or bent glass sheets · CPC title