Design of Energy and Environmentally Friendly Fiberglass Compositions Derived from the Quaternary SiO₂-Al₂O₃-CaO-MgO Phase Diagram - Part II: Fluorine-Free E-Glass Compositions Containing Low Levels of B₂O₃ and Li₂O

Abstract

Incumbent E-Glass compositions contain 6 8% B₂O₃ and 0.1-1.0% fluorine. Partial emissions of these ingredients from commercial melt furnaces were recently identified as environmental hazards. Removal of all fluorine and of essentially all boron was required. But the resulting boron-and fluorine-free E-glass compositions posed another environmental concern. They had higher melt viscosities and fiber forming temperatures, and needed much more process energy. Second and thirdgeneration fluorine-free E-glass compositions were therefore developed, which contained low levels of either B₂O₃ or Li₂O and had a 26°C to 47°C lower forming temperature than optimum first generation compositions. This paper provides a detailed description of third-generation fluorine-free E-glass compositions, which contain low levels of both B₂O₃ and Li₂O, have a 65°C lower forming temperature than optimum first generation boron and fluorine-free E-glass, and promise to offer major process energy savings.