Method and apparatus for producing a thin glass ribbon, and thin glass ribbon produced according to such method

Patent metadata

Field	Value
Publication number	US-10618834-B2
Application number	US-201615351054-A
Country	US
Kind code	B2
Filing date	Nov 14, 2016
Priority date	May 14, 2014
Publication date	Apr 14, 2020
Grant date	Apr 14, 2020

Abstract

An improved method and an improved apparatus are provided for producing a thin glass ribbon, which provide borders at the edges of the ribbon. The edges formed are of high mechanical quality and a formation of new secondary borders after the severing or at least the thickness of such secondary borders is reduced compared to the original borders. The method includes drawing the thin glass ribbon from a molten glass or from a preform, severing the borders, and cooling the resulting glass ribbon. The severing is effected at a location along the moving direction of the thin glass ribbon and at a time at which during the cooling of the thin glass ribbon the viscosity of the glass is in a range from 10 7 dPa·s to 10 11 dPa·s, so that the edges of the thin glass ribbon newly produced by the severing of the borders are rounded off.

First claim

What is claimed is:

1. A method for producing a thin glass ribbon, comprising:
drawing in a moving direction the thin glass ribbon from a molten glass or from a preform in a thickness of not more than 300 μm, the thin glass ribbon having borders at two edges, the borders having a thickness that is greater than a thickness at a center of the thin glass ribbon;
cooling the thin glass ribbon down after drawing; and
severing, during the cooling, the borders from the thin glass ribbon to define new borders of the thin glass ribbon, the severing being effected at a location along the moving direction and at a time at which glass of the thin glass ribbon has a viscosity in a range from 10 7 dPa·s to 10 11 dPa·s, wherein the new borders are round, and wherein the location is a distance in a range from 80 mm to 400 mm from a drawing orifice or a preform heater, wherein the step of severing provides the new borders with a fire-polished surface.

2. The method as claimed in claim 1 , wherein the range is from 10 8 dPa·s to 10 11 dPa·s.

3. The method as claimed in claim 1 , wherein the range is from 10 9 dPa·s to 10 10 dPa·s.

4. The method as claimed in claim 1 , wherein the step of severing comprises using a laser to sever the borders from the thin glass ribbon, wherein the laser melts through the thin glass ribbon.

5. The method as claimed in claim 1 , wherein the step of severing comprises squeezing the thin glass ribbon using wheels without breaking the glass which is still viscoelastic after the drawing.

6. The method as claimed in claim 1 , wherein the severing of the borders is effected with a width in a range from 30 mm to 150 mm.

7. The method as claimed in claim 1 , wherein, after the severing step, the thin glass ribbon has a temperature difference between the new borders and a center of the ribbon of less than 20° C., measured perpendicular to the drawing direction.

8. The method as claimed in claim 1 , wherein the new borders are free of any microcracks.

9. The method as claimed in claim 1 , wherein the new borders have a maximum thickness (D B ), wherein

D
B

≤

2
·

D
use

·
200

⁢

⁢
µm

π

,

wherein D use is the thickness at the center, and
wherein π is the mathematical constant number π.

10. The method as claimed in claim 1 , wherein the thin glass ribbon comprises a lithium aluminosilicate glass having the following composition, in wt %:

SiO 2
55-69,

Al 2 O 3
18-25,

Li 2 O
3-5,

Na 2 O + K 2 O
 0-30,

MgO + CaO + SrO + BaO
0-5,

ZnO
0-4,

TiO 2
0-5,

ZrO 2
0-5,

TiO 2 + ZrO 2 + SnO 2
2-6,

P 2 O 5
0-8,

F
0-1, and

B 2 O 3
0-2.

11. The method as claimed in claim 1 , wherein the thin glass ribbon comprises a soda-lime glass having the following composition, in wt %:

SiO 2
40-81,

Al 2 O 3
0-6,

B 2 O 3
0-5,

Li 2 O + Na 2 O + K 2 O
 5-30,

MgO + CaO + SrO + BaO + ZnO
 5-30,

TiO 2 + ZrO 2
0-7, and

P 2 O 5
0-2.

12. The method as claimed in claim 1 , wherein the thin glass ribbon comprises a borosilicate glass having the following composition, in wt %:

SiO 2
60-85, 

Al 2 O 3
0-10,

B 2 O 3
5-20,

Li 2 O + Na 2 O + K 2 O
2-16,

MgO + CaO + SrO + BaO + ZnO
0-15,

TiO 2 + ZrO 2
0-5, and

P 2 O 5
0-2. 

13. The method as claimed in claim 1 , wherein the thin glass ribbon comp

Assignees

• Schott Ag

Inventors

• Habeck Andreas
• Rossmeier Thomas
• VOGT Jürgen
• Lange Ulrich
• Zachmann Stephan
• Wiegel Thomas

Classifications

• C03B17/064

  by the overflow downdraw fusion process; Isopipes therefor · CPC title

• C03B21/02 Primary

  by cutting (C03B9/46 takes precedence) · CPC title

• C03B21/06

  by flashing-off, burning-off or fusing (C03B9/42 takes precedence) · CPC title

• C03B29/16 Primary

  Glass sheets · CPC title

• C03C3/091

  containing aluminium · CPC title