Patent ID: 8535438

Claim:
A chemically resistant glass composition for the production of reinforcing strands, comprising in mol %: 67-72% SiO 2 5-9.5% ZrO, 11-17% R 2 O where R 2 O is the sum of Na 2 O, K 2 O and Li 2 O 0-5.5% Li 2 O 2.5-5.5% K 2 O less than 10% Na 2 O 3-9% CaO less than 1% of impurities selected from the group consisting of Al 2 O 3 , Fe 2 O 3 , Cr 2 O 3 , TiO 2 , MgO, SrO, BaO and P 2 O 5 ; and the composition being free of F.