Patent ID: 6235667
Filing Date: 2001-05-22
Classification: C03C,Y10S

Abstract:
Essentially lead-free, substantially cesium-free, decolorized glass of improved workability and fusibility, having the characteristics of lead crystal without the presence of lead, a density greater than 2.9 g/cm.sup.3 and a refractive index greater than 1.545, and at most 1% by weight Cs.sub.2 O as an impurity, and suitable for use as imitation lead crystal tableware and decorative crystal glassware, and comprising the following percentage by weight oxide composition:SiO.sub.2 50-58 CaO + MgO + Al.sub.2 O.sub.3 0-4 K.sub.2 O 0-13 TiO.sub.2 + ZrO.sub.2 +Y.sub.2 O.sub.3 0-6 Na.sub.2 O 0-9 SnO.sub.2 + GeO.sub.2 0-5 Li.sub.2 O 0-4 BaO + La.sub.2 O.sub.3 + Nb.sub.2 O.sub.5 + Bi.sub.2 O.sub.3 7-14 CaO 0-3 SiO.sub.2 + Al.sub.2 O.sub.3 52-58 MgO 0-4 K.sub.2 O + Na.sub.2 O + Li.sub.2 O 12-18 B.sub.2 O.sub.3 0-2 ZnO + BaO + La.sub.2 O.sub.3 + Nb.sub.2 O.sub.5 + Bi.sub.2 O.sub.3 26-33 ZnO 16-30 SiO.sub.2 + K.sub.2 O + Na.sub.2 O + Li.sub.2 O + ZnO + at least BaO + Al.sub.2 O.sub.3 + La.sub.2 O.sub.3 + Nb.sub.2 O.sub.5 + Bi.sub.2 O.sub.3 90 BaO 0-13 TiO.sub.2 0-6 ZrO.sub.2 0-5 Y.sub.2 O.sub.3 0-5 Al.sub.2 O.sub.3 0-3 SnO.sub.2 0-5 La.sub.2 O.sub.3 0-9 Nb.sub.2 O.sub.5 0-9 Bi.sub.2 O.sub.3 0-13 GeO.sub.2 0-5wherein the glass composition contains one or more of Sb.sub.2 O.sub.3, As.sub.2 O.sub.3, NiO, CoO, MnO.sub.2, Er.sub.2 O.sub.3, Nd.sub.2 O.sub.3, SeO and CeO.sub.2 as refining and decolorizing agents in a total amount of below 2% by weight, with the Sb.sub.2 O.sub.3 content being 0-1% by weight.