Chemically resistant glass composition for the manufacture of glass reinforcing strands
View Patent ↗The present invention relates to a chemically resistant glass composition for the production of reinforcing strands which comprises the following constituents within the limits defined below, expressed in mol %: SiO 2 67-72%; ZrO 2 5-9.5%, preferably ≧7.5%; R 2 O (R=Na, K and Li) 11-17%; Li 2 O 0-5.5%; K 2 O 0-5.5%; Na 2 O<10%; and CaO 3-9%, the composition furthermore containing less 1% of impurities (Al 2 O 3 , Fe 2 O 3 , Cr 2 O 3 , TiO 2 , MgO, SrO, BaO and P 2 O 5 ) and being free of F. It also relates to the glass strands obtained from this composition and to the composites based on an organic or inorganic material containing such strands.
1. 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.
2. The composition as claimed in claim 1 , characterized in that it satisfies the following relationship:
2.5%<Na 2 O+K 2 O−CaO<9.5%.
3. The composition of claim 1 wherein, the difference between strand forming temperature (Tlogn=3) and liquidus temperature (Tliq) is at least +10° C.
4. The composition of claim 1 , comprising: 5-<10% Na 2 O.
5. The composition of claim 4 , comprising: 1.5-5.5% Li 2 O.
6. The composition of claim 1 , further comprising:
3 to 8.5% CaO.
7. The composition of claim 1 , wherein the Li 2 O/R 2 O and K 2 O/R 2 O molar ratios are ≦5-0.5.
8. The composition of claim 7 , wherein the Li 2 O/R 2 O molar ratio is 5-0.35.
9. The composition of claim 7 , wherein the K 2 O/R 2 0 molar ratio is 0.30.
10. The composition of claim 1 , comprising about 7.5% ZrO 2 .