METHOD FOR PRODUCING CHEMICALLY TEMPERED GLASS
To provide a method for producing chemically tempered glass, whereby frequency of replacement of the molten salt can be reduced. A method for producing chemically tempered glass, which comprises repeating ion exchange treatment of immersing glass in a molten salt, wherein the glass comprises, as represented by mole percentage, from 61 to 77% of SiO 2 , from 1 to 18% of Al 2 O 3 , from 3 to 15% of MgO, from 0 to 5% of CaO, from 0 to 4% of ZrO 2 , from 8 to 18% of Na 2 O and from 0 to 6% of K 2 O; SiO 2 +Al 2 O 3 is from 65 to 85%; MgO+CaO is from 3 to 15%; and R calculated by the following formula by using contents of the respective components, is at least 0.66: R =0.029×SiO 2 +0.021×Al 2 O 3 +0.016×MgO−0.004×CaO+0.016×ZrO 2 +0.029×Na 2 O+0×K 2 O−2.002
1 . (canceled)
2 . A glass for chemical tempering, comprising, as represented by mole percentage based on the following oxides:
from 61 to 66.7% of SiO 2 ;
from 10.2 to 18% of Al 2 O 3 ;
from 0 to 9.1% of MgO;
from 0 to 0.5% CaO;
from 0 to 4% of ZrO 2 ;
from 11 to 14.6% of Na 2 O;
from 0 to 1% of K 2 O; and at least one component selected from the group consisting of B 2 O 3 , SrO and BaO:
wherein
a content of the B 2 O 3 is at most 4.2%,
a total content of SiO 2 and Al 2 O 3 is at most 85%, and
R′ calculated by the following formula by using contents of the respective components, is at least 0.66:
R′= 0.029×SiO 2 +0.021×Al 2 O 3 +0.016×MgO−0.004×CaO+0.016×ZrO 2 +0.029×Na 2 O+0×K 2 O+0.028×B 2 O 3 +0.012×SrO+0.026×BaO−2.002.
3 . The glass for chemical tempering according to claim 2 , wherein a content of Fe 2 O 3 as represented by mass percentage is at most 0.15%.
4 . The glass for chemical tempering according to claim 2 , further comprising at least one component selected from the group consisting of ZnO, Li 2 O and SnO 2 ; wherein a total content of the ZnO, Li 2 O and SnO 2 is at most 2%.
5 . The glass for chemical tempering according to claim 2 , wherein the content of Na 2 O is from 13.6% to 14.6%.
6 . The glass for chemical tempering according to claim 2 , wherein when SrO is present, a content of the SrO is at most 0.5%.
7 . The glass for chemical tempering according to claim 4 , wherein when ZnO is present, a content of ZnO is at most 0.5%.
8 . The glass for chemical tempering according to claim 2 , wherein a total content of SiO 2 , Al 2 O 3 , MgO, CaO, ZrO 2 , Na 2 O, K 2 O, B 2 O 3 , SrO and BaO is at least 98.5%.
9 . The glass for chemical tempering according to claim 2 , wherein no K 2 O is contained.
10 . The glass for chemical tempering according to claim 2 , wherein no Li 2 O is contained.
11 . The glass for chemical tempering according to claim 2 , wherein no ZrO 2 is contained.
12 . The glass for chemical tempering according to claim 2 , wherein the glass for chemical tempering has a thickness of from 0.4 to 1.2 mm.
13 . The glass for chemical tempering according to claim 2 , which further comprises at most 0.15% of SO 3 , a chloride and a fluoride as represented by mass percentage.
14 . The glass for chemical tempering according to claim 2 , which is a cover glass for a display device.
15 . A glass for chemical tempering, comprising, as represented by mole percentage based on the following oxides:
from 61 to 64.6% of SiO 2 ,
from 10.2 to 18% of Al 2 O 3 ,
from 0 to 9.1% of MgO;
from 0 to 0.5% CaO;
from 0 to 4% of ZrO 2 ;
from 11 to 15% of Na 2 O;
from 0 to 1% of K 2 O; and
from 3.4 to 5.6% of B 2 O 3 ;
wherein
a content of Fe 2 O 3 as represented by mass percentage is at most 0.15%, and
R′ calculated by the following formula by using contents of the respective components, is at least 0.66:
R′= 0.029×SiO 2 +0.021×Al 2 O 3 +0.016×MgO−0.004×CaO+0.016×ZrO 2 +0.029×Na 2 O+0×K 2 O+0.028×B 2 O 3 +0.012×SrO+0.026×BaO−2.002.
16 . The glass for chemical tempering according to claim 15 , wherein the content of B 2 O 3 is from 3.4% to 5%.
17 . The glass for chemical tempering according to claim 15 , further comprising at least one component selected from the group consisting of ZnO, Li 2 O and SnO 2 ; wherein a total content of the ZnO, Li 2 O and SnO 2 is at most 2%.
18 . The glass for chemical tempering according to claim 15 , wherein the content of Na 2 O is from 13.6% to 15%.
19 . The glass for chemical tempering according to claim 15 , wherein a content of SrO is at most 0.5%.
20 . The glass for chemical tempering according to claim 15 , wherein when ZnO is present, a content of the ZnO is at most 0.5%.
21 . The glass for chemical tempering according to claim 15 , wherein a total content of SiO 2 , Al 2 O, MgO, CaO, ZrO 2 , Na 2 O, K 2 O, B 2 O 3 , SrO and BaO is at least 98.5%.
22 . The glass for chemical tempering according to claim 15 , wherein no K 2 O is contained.
23 . The glass for chemical tempering according to claim 15 , wherein no Li 2 O is contained.
24 . The glass for chemical tempering according to claim 15 , wherein no ZrO 2 is contained.
25 . The glass for chemical tempering according to claim 15 , wherein the glass for chemical tempering has a thickness of from 0.4 to 1.2 mm.
26 . The glass for chemical tempering according to claim 15 , which further comprises at most 0.15% of SO 3 , a chloride and a fluoride as represented by mass percentage.
27 . The glass for chemical tempering according to claim 15 , which is a cover glass for a display device.