Alkali-free glass substrate and method for producing same

Patent metadata

Field	Value
Publication number	US-9708211-B2
Application number	US-201514919814-A
Country	US
Kind code	B2
Filing date	Oct 22, 2015
Priority date	Apr 23, 2013
Publication date	Jul 18, 2017
Grant date	Jul 18, 2017

Abstract

The present invention relates to an alkali-free glass substrate, having a strain point of 680° C. or higher, a Young's modulus of 78 GPa or greater, an UV transmittance at a wavelength of 300 nm of from 40% to 85% in terms of 0.5 mm thickness, an in-plane distribution of the UV transmittance at a wavelength of 300 nm in a G6-sized substrate of 1% or less in terms of 0.5 mm thickness, an average cooling rate around the glass transition point obtained according to a rate cooling method of 400° C./min or lower, and an in-plane distribution of the average cooling rate of 40° C./min or less.

First claim

The invention claimed is:

1. An alkali-free glass substrate, having a strain point of 680° C. or higher, a Young's modulus of 78 GPa or greater, an UV transmittance at a wavelength of 300 nm of from 40% to 85% in terms of 0.5 mm thickness, an in-plane distribution of the transmittance at a wavelength of 300 nm in a G6-sized substrate of 1% or less in terms of 0.5 mm thickness, an average cooling rate around the glass transition point obtained according to a rate cooling method of 400° C./min or lower, and an in-plane distribution of the average cooling rate of 40° C./min or less, and comprising, on a mass percentage basis in terms of oxides:
SiO 2 50 to 73;
Al 2 O 3 10.5 to 24;
B 2 O 3 0 to 5;
MgO 0 to 10;
CaO 0 to 14.5;
SrO 0 to 24;
BaO 0 to 20;
ZrO 2 0 to 5;
SnO 2 0.01 to 1; and
Fe 2 O 3 0.005 to 0.1,
wherein MgO+CaO+SrO BaO is from 8 to 29.5,
and wherein the alkali-free glass substrate is obtained by managing temperature conditions at the time of forming and annealing such that an average cooling rate around the glass transition point obtained according to a rate cooling method is 400° C./min or lower, an in-plane distribution of the average cooling rate is 40° C./min or less, and an in-plane distribution of the UV transmittance at a wavelength of 300 nm in a G6-sized substrate is 1% or less in terms of 0.5 mm thickness.

2. The alkali-free glass substrate according to claim 1 , having an in-plane distribution of a content of Fe of from 0.001% to 0.003% on a mass percentage basis in terms of Fe 2 O 3 .

3. The alkali-free glass substrate according to claim 1 , having a strain point of 690° C. or higher, a Young's modulus of 80 GPa or greater, an UV transmittance at a wavelength of 300 nm of from 45% to 80% in terms of 0.5 mm thickness, an in-plane distribution of the UV transmittance at a wavelength of 300 nm in a G6-sized substrate of 0.5% or less in terms of 0.5 mm thickness, an average cooling rate around the glass transition point obtained according to a rate cooling method of 350° C./min or lower, and an in-plane distribution of the average cooling rate of 30° C./min or less, and comprising, on a mass percentage basis in terms of oxides:
SiO 2 56 to 70;
Al 2 O 3 16.5 to 22;
B 2 O 3 0.5 to 5;
MgO 3 to 7;
CaO 1 to 10;
SrO 1.5 to 9;
BaO 0 to 6;
ZrO 2 0 to 5;
SnO 2 0.03 to 0.3; and
Fe 2 O 3 0.008 to 0.05,
wherein MgO+CaO+SrO+BaO is from 8 to 29.5.

4. The alkali-free glass substrate according to claim 1 , having a total amount of a halogen element is from 0.001% to 1%, on a mass percentage basis in terms of oxides.

5. The alkali-free glass substrate according to claim 4 , having an in-plane distribution of a content of Fe of from 0.001% to 0.003% on a mass percentage basis in terms of Fe 2 O 3 .

6. A method of producing an alkali-free glass substrate according to claim 1 , having a SiO 2 —Al 2 O 3 —RO (RO is one or more kinds of MgO, CaO, BaO, and, SrO)-based composition, comprising:
a process of preparing glass raw materials so as to make alkali-free glass having a strain point of 680° C. or higher, a Young's modulus of 78 GPa or greater and an UV transmittance at a wavelength of 300 nm of from 40% to 85% in terms of 0.5 mm thickness, and comprising, on a mass percentage basis in terms of oxides,
SiO 2 50 to 73,
Al 2 O 3 10.5 to 24,
B 2 O 3 0 to 5,
MgO 0 to 10,
CaO 0 to 14.5,
SrO 0 to 24,
BaO 0 to 20,
ZrO 2 0 to 5,
SnO 2 0.01 to 1, and
Fe 2 O 3 0.005 to 0.1,
wherein MgO+CaO+SrO+BaO is from 8 to 29.5; and

a process of managing temperature conditions at the time of forming and annealing such that an average cooling rate around the glass transition point obtained according to a rate cooling method is 400° C./min or lower, an in-plane distribution of the average cooling rate is 40° C./min or less, and an in-plane distribution of the UV transmittance at a wavelength of 300 nm in a G6-sized substrate is 1% or less in terms of 0.5 mm thickness.

7. The method of producing an alkali-free glass substrate according to claim 6 , wherein an in-plane distribution of a content of Fe is from 0.001% to 0.003% on a mass percentage basis in terms of Fe 2 O 3 .

8. The method of producing an alkali-free glass substrate according to claim 6 , wherein a total amount of a halogen element is from 0.001% to 1% on a mass percentage basis in terms of oxides.

9. The method of producing an alkali-free glass substrate according to claim 8 , wherein an in-plane distribution of a content of Fe is from 0.001% to 0.003% on a mass percentage basis in terms of Fe 2 O 3 .

Assignees

• Asahi Glass Co Ltd

Inventors

• Tokunaga Hirofumi
• Koike Akio
• Kunigita Masaya

Classifications

• C03C3/085

  containing an oxide of a divalent metal · CPC title

• C03C4/0085 Primary

  for UV-transmitting glass · CPC title

• C03C3/118

  containing aluminium · CPC title

• C03C3/087

  containing calcium oxide, e.g. common sheet or container glass · CPC title

• C03C3/091

  containing aluminium · CPC title