Glass for chemical strengthening, chemically strengthened glass, and method for manufacturing chemically strengthened glass
An object of the present invention is to provide a glass for chemical strengthening which is capable of improving strength as compared with an ordinary soda lime silicate glass even when the same chemical strengthening treatment as that in a conventional process is applied and has good devitrification characteristics, a chemically strengthened glass using the glass for chemical strengthening, and a method for producing the chemically strengthened glass. The present invention provides a glass for chemical strengthening having a specific glass composition described in the present specification.
1. A glass, comprising, as expressed by mass percentage based on oxides, 64 to 72% of SiO 2 , 4.4 to 7% of Al 2 O 3 , 7 to 10.9% of MgO, 0.1 to 5% of CaO, 14 to 19% of Na 2 O, and 0 to 3% of K 2 O, wherein RO is 8 to 11% wherein the RO represents the sum of alkaline earth metal oxides, and RO/(RO+R 2 O) is 0.20 or more and 0.42 or less, wherein the R 2 O represents the sum of alkali metal oxides,
and wherein the glass has a temperature (T 2 ) at which a viscosity is 10 2 dPa·s of 1550° C. or lower.
2. The glass according to claim 1 , wherein the RO/(RO+R 2 O) is 0.40 or less.
3. The glass according to claim 1 , comprising 5% or more of Al 2 O 3 .
4. The glass according to claim 1 , comprising 8% or more of MgO.
5. The glass according to claim 1 , comprising 10% or less of MgO.
6. The glass according to claim 1 , further comprising 0 to 4% of B 2 O 3 , 0 to 1% of Fe 2 O 3 and 0 to 1% of TiO 2 .
7. The glass according to claim 1 , which has been formed according to a float process.
8. A chemically strengthened glass obtained by chemically strengthening the glass according to claim 1 .
9. The chemically strengthened glass according to claim 8 , having a surface compressive stress of 300 MPa or more.
10. The chemically strengthened glass according to claim 8 , having a depth of compressive stress of 10 μm or more.
11. A method for producing a chemically strengthened glass, comprising a chemical strengthening step of subjecting the glass according to claim 1 to an ion-exchange treatment.
12. The glass according to claim 1 , comprising 64.1 to 72% of SiO 2 and 4.4 to 6.9% of Al 2 O 3 .
13. The glass according to claim 1 , comprising 64.3 to 72% of SiO 2 and 4.4 to 6.7% of Al 2 O 3 .
14. The glass according to claim 1 , comprising 65.6 to 72% of SiO 2 and 4.4 to 5.9% of Al 2 O 3 .