Glass compositions with high softening point temperatures

Abstract

Provided are glass compositions with higher softening point temperatures than conventional glasses, which improve flame penetration test performance of flexible duct insulation. In particular, the glass compositions have a softening point in the range of about 1230-1276° F., a log-3 viscosity temperature in the range of about 1802-1879° F., and a temperature difference between log-3 viscosity and liquidus temperatures of at least 150° F. These glasses are specially formulated to increase softening point while only minimally increasing log-3 viscosity temperature, so as to allow fiber insulation manufacturing without requiring increased energy use.

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