US 12,246,980 B2
Glass substrate for vehicle glazing, in particular for the windscreen of a vehicle
Thomas Seuthe, Jena (DE); Thilo Zachau, Neuengönna (DE); Thomas Schmiady, Jena (DE); Sandra von Fintel, Jena (DE); and Jochen Alkemper, Klein Winternheim (DE)
Assigned to SCHOTT AG, Mainz (DE)
Filed by SCHOTT AG, Mainz (DE)
Filed on Mar. 4, 2020, as Appl. No. 16/808,520.
Claims priority of application No. 10 2019 105 421.4 (DE), filed on Mar. 4, 2019.
Prior Publication US 2020/0354253 A1, Nov. 12, 2020
Int. Cl. C03B 18/06 (2006.01); C03B 18/20 (2006.01); C03C 3/089 (2006.01); C03C 3/091 (2006.01)
CPC C03B 18/06 (2013.01) [C03B 18/20 (2013.01); C03C 3/089 (2013.01); C03C 3/091 (2013.01)] 26 Claims
OG exemplary drawing
 
1. A method for producing a glass substrate for vehicle glazing, comprising:
hot forming a borosilicate glass to have an average thickness from 0.3 mm to 5 mm in a hot forming section;
adjusting a viscosity of the borosilicate glass to be between log (η/dPa·s)=4.8 and log (η/dPa·s)=5.5 at a beginning of the hot forming section by temperature control,
wherein the temperature control comprises a heat absorbing chamber upstream of a throughput control component and ceiling heaters of a float bath furnace that has a tin bath onto which molten glass to be hot formed into the borosilicate glass is transferred through the throughput control component,
wherein the heat absorbing chamber comprises fluid flow areas forming a metallic pipe system through which water flows and which absorb heat from the molten glass to be hot formed,
wherein the metallic pipe system comprises a heat-absorbing dye or a temperature-resistant paint on a surface thereof;
maintaining an aging velocity (Av) of glass to be hot formed while stretching the borosilicate glass in a flow direction or a longitudinal direction of movement of the borosilicate glass in the hot forming section to not exceed 10 mm/s and to not undershoot 3 mm/s;
wherein the following equation applies to the aging velocity (Av):
Av=(a difference in velocity in the hot forming section)*Bg/Hsl
where:
Bg is a width of the borosilicate glass to be hot formed in the hot forming section; and
Hsl is a length of hot forming section along which the borosilicate glass is stretched;
maintaining the width Bg so that the width Bg is altered by less than 3% in the hot forming section; and
adjusting the viscosity of the borosilicate glass to be between log (η/dPa·s)=7.1 and log (η/dPa·s)=7.6 at an end of the hot forming section.