Chemically strengthened glass, and glass for chemical strengthening

Abstract

A glass for chemical strengthening contains, in mole percentage on an oxide basis, 58 to 80% of SiO2, 13 to 18% of Al2O3, 0 to 5% of B2O3, 0.5 to 4% of P2O5, 4 to 10% of Li2O, 5 to 14% of Na2O, 0 to 2% of K2O, 0 to 11% of MgO, 0 to 5% of CaO, 0 to 20% of SrO, 0 to 15% of BaO, 0 to 10% of ZnO, 0 to 1% of TiO2, and 0 to 2% of ZrO2. A value of X is 30000 or more. The value of X is calculated based on the formula, X=SiO2×329+Al2O3×786+B2O3×627+P2O5×(−941)+Li2O×927+Na2O×47.5+K2O×(−371)+MgO×1230+CaO×1154+SrO×733+ZrO2×51.8, by using the contents in mole percentage on an oxide basis of components.

1 - 7 . (canceled) 
     
     
         8 . A chemically strengthened glass sheet, comprising a glass which comprises, in mole percentage on an oxide basis, 58 to 72% of SiO 2 , 13 to 18% of Al 2 O 3 , 0 to 5% of B 2 O 3 , 0.5 to 4% of P 2 O 5 , 4 to 13% of Li 2 O, 7 to 14% of Na 2 O, 0 to 2% of K 2 O, 0 to 11% of MgO, 0 to 14% of CaO, 0 to 12% of SrO, 0 to 15% of BaO, 0 to 10% of ZnO, 0 to 1% of TiO 2 , and 0 to 2% of ZrO 2 , wherein:
 the chemically strengthened glass sheet has a surface compressive stress (CS) of 450 MPa or more;   a compressive stress value (CS 90 ) in a portion at a depth of 90 μm from a surface of the chemically strengthened glass sheet is 25 MPa or more, or a compressive stress value (CS 100 ) in a portion at a depth of 100 μm from the surface is 15 MPa or more;   a depth d h  of a portion at which a magnitude of an internal compressive stress of the chemically strengthened glass sheet reaches ½ of a surface compressive stress (CS) of the chemically strengthened glass sheet is 30 μm or less; and   a value of X is 30000 or more, the value of X being calculated based on the following formula by using contents in mole percentage on an oxide basis of components of SiO 2 , Al 2 O 3 , B 2 O 3 , P 2 O 5 , Li 2 O, Na 2 O, K 2 O, MgO, CaO, SrO, BaO, and ZrO 2 :
   X=SiO 2 ×329+Al 2 O 3 ×786+B 2 O 3 ×627+P 2 O 5 ×(−941)+Li 2 O×927+Na 2 O×47.5+K 2 O×(−371)+MgO×1230+CaO×1154+SrO×733+ZrO 2 ×51.8.
 
   
     
     
         9 . The chemically strengthened glass sheet according to  claim 8 , wherein the chemically strengthened glass sheet has a thickness of 2 mm or less. 
     
     
         10 . The chemically strengthened glass sheet according to  claim 8 , wherein a product (CS 100 ×t 2 ) of a compressive stress value CS 100  (MPa) in a portion at a depth of 100 μm from the surface and a square of a thickness t (mm) of the chemically strengthened glass sheet is 5 MPa·mm 2  or more. 
     
     
         11 . The chemically strengthened glass sheet according to  claim 8 , wherein an area Sc (MPa-μm) of a compressive stress layer of the chemically strengthened glass sheet is 30000 MPa·μm or more. 
     
     
         12 . The chemically strengthened glass sheet according to  claim 8 , wherein the depth d h  is 8 μm or more. 
     
     
         13 . The chemically strengthened glass sheet according to  claim 8 , wherein a depth of a compressive stress layer (DOL) of the chemically strengthened glass sheet is 110 μm or more.