Patent ID: 6518211
Filing Date: 2003-02-11
Classification: C03C,Y10T

Abstract:
A boron-free float glass having a density which is less than 2.48 g/cm3 and a composition capable of being chemically strengthened over a period of less than 100 hours to exhibit a surface stress of at least 400 Mpa with a depth of ion penetration greater than 200 microns comprising:SiO258% to70% (by weight)Al2O35% to15%Na2O12% to18%K2O0.1% to5%MgO4% to10%CaO0% to1%with the provisos that the sum of the Al2O3 and MgO exceeds 13%, that the sum of the amounts of Al2O3 plus MgO divided by the amount of K2O exceeds 3 and that the sum of the Na2O plus K2O plus MgO exceeds 22%.