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1. EP1911725 - PROCESS FOR PRODUCTION OF NON-ALKALINE GLASS AND NON-ALKALINE GLASS

Office European Patent Office
Application Number 06780807
Application Date 05.07.2006
Publication Number 1911725
Publication Date 16.04.2008
Publication Kind A4
IPC
C CHEMISTRY; METALLURGY
03
GLASS; MINERAL OR SLAG WOOL
B
MANUFACTURE OR SHAPING OF GLASS, OR OF MINERAL OR SLAG WOOL; SUPPLEMENTARY PROCESSES IN THE MANUFACTURE OR SHAPING OF GLASS, OR OF MINERAL OR SLAG WOOL
5
Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
16
Special features of the melting process; Auxiliary means specially adapted for glass-melting furnaces
225
Refining
C CHEMISTRY; METALLURGY
03
GLASS; MINERAL OR SLAG WOOL
C
CHEMICAL COMPOSITION OF GLASSES, GLAZES, OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
3
Glass compositions
04
containing silica
076
with 40% to 90% silica by weight
089
containing boron
091
containing aluminium
C03B 5/225
C03C 3/091
CPC
C03B 5/225
C03B 5/2252
C03C 1/004
C03C 3/091
Y02P 40/57
Applicants ASAHI GLASS CO LTD
Inventors NISHIZAWA MANABU
KASE JUNICHIRO
SAITO KENTA
MAEDA KEI
MATSUMOTO SYUJI
Priority Data 2005197528 06.07.2005 JP
2006313431 05.07.2006 JP
Title
(DE) VERFAHREN ZUR HERSTELLUNG VON NICHTALKALISCHEM GLAS UND NICHTALKALISCHES GLAS
(EN) PROCESS FOR PRODUCTION OF NON-ALKALINE GLASS AND NON-ALKALINE GLASS
(FR) PROCÉDÉ DE PRODUCTION D'UN VERRE NON ALCALIN ET VERRE NON ALCALIN
Abstract
(EN)
To provide a process for producing an alkali free glass for effectively suppressing bubbles, and an alkali free glass produced by the process, which is suitable as a glass substrate for flat panel displays and has few bubbles. A process for producing an alkali free glass containing substantially no alkali metal oxide, which comprises melting a glass starting material having a matrix composition of the following composition, and subjecting the molten glass to a treatment process of removing bubbles under reduced pressure, stirring or transferring under a condition where the molten glass is in contact with a platinum member, wherein the starting material is prepared so as to contain SnO 2 in an amount of from 0.01 to 2.0% per 100% of the total amount of the above matrix composition; the starting material is melted under heating at from 1,500 to 1,650°C; then bubbles contained in the molten glass are permitted to rise to the surface of the molten glass, together with oxygen bubbles generated by a reduction reaction in which SnO 2 in the molten glass is reduced to SnO; and in the above treatment process, the oxygen bubbles generated at the interface between the molten glass and the platinum member are permitted to be absorbed by an oxidation reaction in which SnO is oxidized to SnO 2 , under a condition where the molten glass is from 1,300 to 1,500°C. Composition as represented by the mass percentage: SiO 2 58.4 to 66.0%, Al 2 O 3 15.3 to 22.0%, B 2 O 3 5.0 to 12.0%, MgO 0 to 6.5%, CaO 0 to 7.0%, SrO 4 to 12.5%, BaO 0 to 2.0%, MgO+CaO+SrO+BaO 9.0 to 18.0%.