Process for producing glass tubes and use thereof

A process for producing glass tubes is provided that includes: applying a glass melt onto the outer surface of a rotating cylindrical shaping body to form thereon a hollow glass melt body; and withdrawing the hollow glass melt body over the shaping body toward a front end for forming a glass tube; w...

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1. Verfasser: KASS CHRISTOF
Format: Patent
Sprache:eng
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Zusammenfassung:A process for producing glass tubes is provided that includes: applying a glass melt onto the outer surface of a rotating cylindrical shaping body to form thereon a hollow glass melt body; and withdrawing the hollow glass melt body over the shaping body toward a front end for forming a glass tube; wherein the shaping body is coated with platinum or a platinum alloy in regions that are in contact with the glass melt. The glass melt has a composition in wt.-% of: SiO2 71.0 to 77.0; B2O3 9.0 to 12.0; Na2O 5.5 to 8.0; K2O 0.0 to 2.0; Al2O3 6.5 to 8.0; CaO 0.0 to 1.5; BaO 0.0 to 2.0; Li2O 0.0 to 0.5; ZrO2 0.0 to 5.0. The glass composition provides enhanced devitrification characteristics so that glass tubes can be drawn using a Danner mandrel that is coated with platinum or a platinum alloy.