Chemically strengthened glass
The present invention relates to a chemically strengthened glass, in which CT 1 and CT 5 satisfy CT 5 /CT 1 ≤0.85, the CT 1 satisfies CT 1 >−38.7×ln(t/1000)+48.2 [MPa] and an internal energy density rE satisfies rE≤23.3×t/1000+15 [kJ/m 2 ]. CS is a surface compressive stress value [MPa], σ (x) is a compressive stress value [MPa] at a position x in a depth direction, DOL is a compressive stress depth [μm], and t is a sheet thickness [μm].
1. A chemically strengthened glass, wherein:
a CT 1 obtained by formula (1) and an internal tensile stress CT 5 obtained by formula (5) satisfy CT 5 /CT 1 ≤0.85;
the internal tensile stress CT 5 is 30 MPa or more;
a compressive stress value at a depth of a half value of the compressive stress depth DOL from the surface of the chemically strengthened glass is 10% or less of the surface compressive stress CS;
when a sheet thickness of the chemically strengthened glass is t (μm), the CT 1 satisfies CT 1 >−38.7×ln(t/1000)+48.2 [MPa]; and
an internal energy density rE obtained by formula (6) satisfies rE≤23.3×t/1000+15 [kJ/m 2 ]:
CT
1
=
CS
×
DOL
(
t
-
2
×
DOL
)
(
1
)
CT
5
=
2
×
∫
0
DOL
σ
(
x
)
dx
(
t
-
2
×
DOL
)
(
5
)
rE
=
CT
5
×
(
t
-
2
×
DOL
)
2
1000
×
t
(
6
)
wherein
CS is a surface compressive stress value [MPa] of the chemically strengthened glass,
σ (x) is a compressive stress value [MPa] at a position x in a depth direction from a surface of the chemically strengthened glass,
DOL is a compressive stress depth [μm] of the chemically strengthened glass, and
t is a sheet thickness [μm] of the chemically strengthened glass.
2. The chemically strengthened glass according to claim 1 , wherein the surface compressive stress CS is 600 MPa or more.
3. The chemically strengthened glass according to claim 1 , wherein the compressive stress depth DOL is 30 μm or more.
4. The chemically strengthened glass according to claim 1 , wherein the sheet thickness t is 1500 μm or less.
5. The chemically strengthened glass according to claim 1 , wherein a position HW having a compressive stress being a half value of the surface compressive stress CS is a position less than 8 μm from the surface of the chemically strengthened glass.
6. The chemically strengthened glass according to claim 1 , wherein the internal tensile stress CT 5 satisfies CT 5 >−38.7×ln(t/1000)+48.2 [MPa].
7. The chemically strengthened glass according to claim 1 , wherein the internal tensile stress CT 5 [MPa] is 1.1 times or more a CT limit value [MPa] obtained by formula (2):
CT limit =−38.7×ln( t/ 1000)+48.2 (2),
wherein t is the sheet thickness [μm] of the chemically strengthened glass.
8. The chemically strengthened glass according to claim 1 , wherein the internal tensile stress CT 5 [MPa] is 1.1 times or more a CT limit value [MPa] obtained by formula (4):
CT limit =−36.7×ln( t/ 1000)+48.7 (4),
wherein t is the sheet thickness [μm] of the chemically strengthened glass.
9. The chemically strengthened glass according to claim 1 , wherein the CT 1 [MPa] is 1.1 times or more a CT limit value [MPa] obtained by formula (2):
CT limit =−38.7×ln( t/ 1000)+48.2 (2),
wherein t is the sheet thickness [μm] of the chemically strengthened glass.
10. The chemically strengthened glass according to claim 1 , wherein the CT 1 [MPa] is 1.1 times or more a CT limit value [MPa] obtained by formula (4):
CT limit =−36.7×ln( t/ 1000)+48.7 (4),
wherein t is the sheet thickness [μm] of the chemically strengthened glass.
11. The chemically strengthened glass according to claim 1 , wherein the internal tensile stress CT 5 [MPa] is 1.5 times or more a CT limit value [MPa] obtained by formula (2):
CT limit =−38.7×ln( t/ 1000)+48.2 (2),
wherein t is the sheet thickness [μm] of the chemically strengthened glass.
12. The chemically strengthened glass according to claim 1 , wherein the internal tensile stress CT 5 [MPa] is 2.0 times or more a CT limit value [MPa] obtained by formula (2):
CT limit =−38.7×ln( t/ 1000)+48.2 (2),
wherein t is the sheet thickness [μm] of the chemically strengthened glass.
13. The chemically strengthened glass according to claim 1 , wherein the internal tensile stress CT 5 [MPa] is 3.0 times or more a CT limit value [MPa] obtained by formula (2):
CT limit =−38.7×ln( t/ 1000)+48.2 (2),
wherein t is the sheet thickness [μm] of the chemically strengthened glass.
14. The chemically strengthened glass according to claim 1 , wherein the internal tensile stress CT 5 [MPa] is 1.5 times or more a CT limit value [MPa] obtained by formula (4):
CT limit =−36.7×ln( t/ 1000)+48.7 (4),
wherein t is the sheet thickness [μm] of the chemically strengthened glass.
15. The chemically strengthened glass according to claim 1 , wherein the internal tensile stress CT 5 [MPa] is 2.0 times or more a CT limit value [MPa] obtained by formula (4):
CT limit =−36.7×ln( t/ 1000)+48.7 (4),
wherein t is the sheet thickness [μm] of the chemically strengthened glass.
16. The chemically strengthened glass according to claim 1 , wherein the internal tensile stress CT 5 [MPa] is 3.0 times or more a CT limit value [MPa] obtained by formula (4):
CT limit =−36.7×ln( t/ 1000)+48.7 (4),
wherein t is the sheet thickness [μm] of the chemically strengthened glass.