Glass for chemical strengthening, chemically strengthened glass, and electronic device case
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·m 1/2 ; a thermal conductivity at 20° C. of at least 1.3 W/m·K; and comprises a lithium aluminosilicate crystallized glass.
1. A glass for chemical strengthening, comprising a lithium aluminosilicate crystallized glass, and comprising, as expressed by mass % on an oxide basis:
58 to 71% of SiO 2 ;
8 to 30% of Al 2 O 3 ;
1 to 15% of Li 2 O;
1 to 5% of Na 2 O;
0 to 2% of K 2 O;
0 to 6% of SnO 2 ;
0 to 8% of ZrO 2 ;
0 to 6% 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 4 to 12%,
wherein the glass for chemical strengthening is free of As 2 O 3 and Sb 2 O 3 , and
the glass for chemical strengthening 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.
2. The glass for chemical strengthening according to claim 1 , having a Vickers hardness of 680 or more.
3. The glass for chemical strengthening according to claim 1 , wherein the crystallized glass comprises a β-spodumene.
4. The glass for chemical strengthening according to claim 1 , comprising, as expressed by mass % on an oxide basis:
60 to 70% of SiO 2 ,
12 to 25% of Al 2 O 3 ;
1.5 to 10% of Li 2 O;
1 to 4% of Na 2 O;
0 to 5% of SnO 2 ,
0 to 6% of ZrO 2 ; and
0 to 5% of P 2 O 5 .
5. The glass for chemical strengthening according to claim 1 , which is free of BaO.
6. The glass for chemical strengthening according to claim 1 , which is free of K 2 O.
7. The glass for chemical strengthening according to claim 1 , which is free of TiO 2 .
8. The glass for chemical strengthening according to claim 1 , having the haze value of 0.4% or lower.
9. The glass for chemical strengthening according to claim 1 , wherein a content ratio Li 2 O/Al 2 O 3 between Li 2 O and Al 2 O 3 is 0.3 or less.
10. The glass for chemical strengthening according to claim 1 , wherein a ratio SnO 2 /(SnO 2 +ZrO 2 ) of the SnO 2 content to the total of SnO 2 and ZrO 2 is 0.3 to 0.7.
11. A chemically strengthened glass, comprising a lithium aluminosilicate crystallized glass, and comprising, as expressed by mass % on an oxide basis:
58 to 71% of SiO 2 ;
8 to 30% of Al 2 O 3 ;
1 to 15% of Li 2 O;
1 to 5% of Na 2 O;
0 to 2% of K 2 O;
0 to 6% of SnO 2 ;
0 to 8% of ZrO 2 ;
0 to 6% 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 4 to 12%,
wherein the glass for chemical strengthening is free of As 2 O 3 and Sb 2 O 3 , and
the glass for chemical strengthening 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;
a thermal conductivity at 20° C. of 1.3 W/m·K or more; and
a surface compressive stress of 500 MPa or more, and a depth of a compressive stress layer of 45 μm or more.
12. The chemically strengthened glass according to claim 11 , having a Vickers hardness of 700 or more.
13. The chemically strengthened glass according to claim 11 , wherein the crystallized glass comprises a β-spodumene.
14. The chemically strengthened glass according to claim 11 , comprising, as expressed by mass % on an oxide basis:
60 to 70% of SiO 2 ,
12 to 25% of Al 2 O 3 ;
1.5 to 10% of Li 2 O;
1 to 4% of Na 2 O;
0 to 5% of SnO 2 ;
0 to 6% of ZrO 2 ; and
0 to 5% of P 2 O 5 .
15. The chemically strengthened glass according to claim 11 , 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.
16. An electronic device housing member comprising the chemically strengthened glass according to claim 11 .
17. An electronic device housing, wherein a surface area of a part formed of the chemically strengthened glass according to claim 11 occupies 40% or higher with respect to a surface area of the housing.
18. The electronic device housing according to claim 17 , wherein a thickness of a thinnest part of the chemically strengthened glass is 0.6 mm or less.