Borosilicate glass composition for producing glass tubes and its use for producing glass tubes and as outer tube for lamps

摘要

A glass composition and its use for producing glass tubes is provided. The glass tubes having the provided composition are particularly suitable for the outer tubes of fluorescent lamps in the case of which a phosphor layer is baked at temperatures of up to 700° C. The tubes composed of the glass of the provided composition have a lower tendency to deform or stick together when processed at high temperatures. To obtain the observed effects, the molar ratio of Na2O/(Na2O+K2O), inter alia, is greater than 0.4 and not more than 0.72.

主权项

1. A borosilicate glass comprising, in mol % on an oxide basis:
SiO2 74-81; B2O3 8.5-14.5; Al2O3 0.5-3.5; Na2O 1.5-3.5; K2O 1.0-2.0; Li2O 0-1.0: MgO 0.5-1.5; CaO 0.5-1.5; BaO 0-0.6; TiO2 2.0-3.5; ZrO2 0-1.0, and as refining agents Sb2O3 0-0.15; CeO2 0-0.5; and SnO2 0-0.5, and having a molar ratio of Na2O/(Na2O+K2O) that is greater than 0.4, but less than 0.72.