Glass for chemical strengthening, chemically strengthened glass, and electronic device case

Abstract

The present invention pertains to a glass for strengthening, that: has an average transmittance of at least 70% when converted to a thickness of 0.8 mm at a wavelength of 380-780 nm; has a haze value of no more than 0.7% when converted to a thickness of 0.8 mm in a C light source; has a Young's modulus of at least 85 GPa; has a fracture toughness value of at least 0.90 MPa·m1/2; a thermal conductivity at 20° C. of at least 1.3 W/m·K; and comprises a lithium aluminosilicate crystallized glass.

1 - 4 . (canceled) 
     
     
         5 . A chemically strengthened glass, comprising a lithium aluminosilicate crystallized glass, and comprising, as expressed by mass % on an oxide basis:
 4 to 15% of Li 2 O;   0.2 to 4% of Na 2 O;   0 to 2% of K 2 O;   0 to 4% of SnO 2 ;   1 to 8% of ZrO 2 ;   1 to 4% of P 2 O 5 ;   0 to 1% of BaO; and   0 to 2% of ZnO,   a total of SnO 2  and ZrO 2  being 3 to 8%,   wherein the glass is free of As 2 O 3  and Sb 2 O 3 , and   the glass has:   an average transmittance at a wavelength of 380 to 780 nm of 70% or higher in terms of a thickness of 0.8 mm;   a haze value of 0.7% or lower in terms of the thickness of 0.8 mm at a C illuminant;   a Young's modulus of 85 GPa or more;   a fracture toughness value of 0.90 MPa·m 1/2  or more; and   a thermal conductivity at 20° C. of 1.3 W/m·K or more.   
     
     
         6 . The chemically strengthened glass according to  claim 5 , having a Vickers hardness of 700 or more. 
     
     
         7 . The chemically strengthened glass according to  claim 5 , wherein the crystallized glass comprises a β-spodumene. 
     
     
         8 . The chemically strengthened glass according to  claim 5 , further comprising, as expressed by mass % on an oxide basis:
 0 to 2% of CaO;   0 to 0.25% of TiO 2 ; and   0 to 3% of B 2 O 3 ,   a total of Na 2 O and K 2 O being 0.3 to 4%.   
     
     
         9 . The chemically strengthened glass according to  claim 5 , wherein the depth of a compressive stress layer is 60 μm or more, and a maximum depth where a compressive stress value is 50 MPa or more is 50 μm or more. 
     
     
         10 . An electronic device housing member comprising the chemically strengthened glass according to  claim 5 . 
     
     
         11 . An electronic device housing, wherein a surface area of a part formed of the chemically strengthened glass according to  claim 5  occupies 40% or higher with respect to a surface area of the housing. 
     
     
         12 . The electronic device housing according to  claim 11 , wherein a thickness of a thinnest part of the chemically strengthened glass is 0.6 mm or less. 
     
     
         13 . The chemically strengthened glass according to  claim 5 , having a depth of a compressive stress layer of 45 μm or more. 
     
     
         14 . The chemically strengthened glass according to  claim 5 , having a surface compressive stress of 500 MPa or more.