PHOTOCHROMIC GLASSES SUITABLE FOR SIMULTANEOUS HEAT TREATMENT AND SHAPING

摘要

PHOTOCHROMIC GLASSES SUITABLE FOR SIMULTANEOUS HEAT TREATMENT AND SHAPING The instant invention is related to the manufacture of photochromic glasses having base compositions with m a very narrow interval of the alkali metal boroaluminosilicate system wherein silver chloride and/or silver bromide crystals impart photochromic properties. The glasses are notable for their rapid fading characteristics and relatively low temperature dependence of darkening. The compositions are especially suitable for a production process which contemplates simultaneously shaping articles from glass sheet and developing photochromic properties therein.