COLORLESS MINERAL GLASSES WITH ABSTRACT OPTICAL ABSORPTION FRONT BETWEEN 370 AND 425 NM; PRODUCTS IN SAID GLASSES

摘要

The object of the present invention is colourless inorganic glasses, as well as products manufactured from said glasses. Said glasses are of the type containing copper halides or copper cadmium halides and having a sharp optical absorption cutoff between 370 nm and 425 nm; essentially having the composition below, expressed in cationic percentages: 23-73 % SiO2; 15-45 % B2O3; 0-24 % Al2O3; 0-12 % Li2O; 0-20 % Na2O; 0-12 % K2O; 0.25-5 % CaO+BaO+SrO; 0.125-1 % Cu2O; 0-1 % CdO; 0-5 % ZrO2; with (I) 0.25-2 % Cl+Br; and 0-2 % F; the Cl, Br and F contents being themselves expressed in percentages by weight of the total composition; the weight content of bromine being greater than the weight content of chlorine (Br Cl); with an adequate amount of reducing agent(s) which is (are) advantageously selected from SnO2, As2O3, Sb2O3, and mixtures thereof, in order to have mainly, in said glasses, the copper in the form of cuprous ions (Cu+), and therefore glasses which have neither a red coloration, nor a blue green coloration; and the residual yellow coloration of which is minimised.