US Patent 9896374 Glass for chemical tempering and chemically tempered glass

To provide chemically tempered glass which is less likely to break even if scratched. Chemically tempered glass, which comprises, as represented by mole percentage based on the following oxides, from 56 to 72% of SiO2, from 8 to 20% of Al2O3, from 9 to 25% of Na2O, from 0 to 2% of K2O, and from 0 to 15% of MgO, and which has a surface compressive stress of at least 900 MPa and an internal tensile stress of at most 30 MPa. Glass for chemical tempering, which comprises, as represented by mole percentage based on the following oxides, from 56 to 69% of SiO2, from 8 to 16% of Al2O3, from 9 to 22% of Na2O, from 0 to 1% of K2O, from 5.5 to 14% of MgO, from 0 to 2% of ZrO2, and from 0 to 6% of B2O3.