Patent ID: 7875566

Claim:
Fibres having the composition in weight percent 65%<SiO 2 <86% MgO<10% 13.5%<CaO<27.5% Al 2 O 3 <2% ZrO 2 <3% B 2 O 3 <5% P 2 O 5 <5% 72%<SiO 2 +ZrO 2 +B 2 O 3 +5*P 2 O 5 95%<SiO 2 +CaO+MgO+Al 2 O 3 +ZrO 2 +B 2 O 3 +P 2 O 5 0.2%<M 2 O<1.5% in which M is alkali metal and in which at least 75 mol % of the alkali metal is potassium and soluble in physiological saline solution to give non-toxic dissolved components.