Glass which can be compression moulded at relatively low temps. - made from the oxides of phosphorus, lead, lithium, sodium, and barium fluoride (NL 7.4.81)

摘要

The glass is mouldable at below 450 deg.C, and is melted using a batch contg. in mol.% 25-55% P2O5, 15-45% R2O, 0-20% RO; where R2O contains 0-45% Li2O, 0-20% Na2O, 0-10% K2O; and RO contains 0-10% MgO, 0-15% CaO, 0-20% SrO, 0-20% BaO; and after melting, the glass contains 0.3-3 wt.% F. The glass pref. also contains max. 25% made up from, all maxima, 20% PbO, 7% La2O3, 12% ZnO. When the P2O5 is below 30%, a max. of 25% B2O3 may be present, but only max. 5% B2O3 when the P2O5 exceeds 45%. The esp. pref. glass (I) can be compression moulded below 350 deg.C and is made from a batch contg. 53% P2O5, 12.5% PbO, 15.9% BaF2, 9.3% Li2O, 9.3% Na2O. The glass is used e.g., in the compression moulding of spectacle lenses which donot need grinding or polishing.