Glass yarns, composite thereof, method for making same and reinforcing glass composition

摘要

Reinforcing glass yarn, the composition of which comprises the following constituents, within the limits defined below, expressed in percentages by weight: SiO₂ 54.5 to 58% Al₂O₃ 12 to 15.5% SiO₂ + Al₂O₃ 70 to 73% CaO 17 to 25% MgO 0 to 5% RO = CaO + MgO 21 to 28% R₂O = Na₂O + K₂O + Li₂O up to 2% TiO₂ less than 1% Fe₂O₃ less than 0.5% B₂O₃ up to 3% F₂ less than 1% and such that the ratio R 1 =Al₂O₃/CaO is less than 0.7, and when SiO₂ is greater than 57% the amount of boron oxide B₂O₃ is greater than 2%.