Cover glass and method for producing cover glass

Abstract

The disclosed cover glass is produced by etching a glass substrate that has been formed by a down-drawing process, and chemically strengthening the glass substrate to provide the glass substrate with a compressive-stress layer on the principal surfaces thereof. The glass substrate contains, as components thereof, 50% to 70% by mass of SiO 2 , 5% to 20% by mass of Al 2 O 3 , 6% to 30% by mass of Na 2 O, and 0% to less than 8% by mass of Li 2 O. The glass substrate may also contain 0% to 2.6% by mass of CaO, if necessary. The glass substrate has an etching characteristic in which the etching rate is at least 3.7 μm/minute in an etching environment having a temperature of 22° C. and containing hydrogen fluoride with a concentration of 10% by mass.

What is claimed is: 
     
         1 . A method for producing a cover glass, comprising:
 subjecting a glass substrate to shape-processing by etching, the glass substrate having been formed into a plate-like shape by a down-drawing process and containing, as components thereof, 50% to 70% by mass of SiO 2 , 5% to 20% by mass of Al 2 O 3 , 6% to 30% by mass of Na 2 O, and 0% to less than 8% by mass of Li 2 O; and   forming a compressive-stress layer on the shape-processed glass substrate by subjecting the glass substrate to chemical strengthening.   
     
     
         2 . The method for producing a cover glass according to  claim 1 , wherein the glass substrate further contains, as a component thereof, 0% to 2.6% by mass of CaO. 
     
     
         3 . The method for producing a cover glass according to  claim 1 , wherein, if the content by percentage of the SiO 2  is X % by mass and the content by percentage of the Al 2 O 3  is Y % by mass, X−1/2·Y is at most 57.5% by mass. 
     
     
         4 . The method for producing a cover glass according to  claim 3 , wherein the X−1/2·Y is at least 45% by mass. 
     
     
         5 . The method for producing a cover glass according to  claim 1 , wherein the etching is chemical etching. 
     
     
         6 . A method for producing a cover glass, comprising:
 subjecting a glass substrate to shape-processing, the glass substrate having been formed into a plate-like shape and containing, as components thereof, 50% to 70% by mass of SiO 2 , 5% to 20% by mass of Al 2 O 3 , 6% to 30% by mass of Na 2 O, 0% to less than 8% by mass of Li 2 O, and 0% to 2.6% by mass of CaO;   processing at least an end surface of the shape-processed glass substrate by chemical etching; and   forming a compressive-stress layer on the processed glass substrate by subjecting the glass substrate to chemical strengthening.   
     
     
         7 . The method for producing a cover glass according to  claim 6 , wherein, if the content by percentage of the SiO 2  is X % by mass and the content by percentage of the Al 2 O 3  is Y % by mass, X−1/2·Y is at most 57.5% by mass.