Production method of chemically strengthened glass, and chemically strengthened glass

Abstract

The present invention relates to a method for producing a chemically strengthened glass, the method including, performing a chemical strengthening treatment including the following steps (1) to (3) to a glass having a specific composition, (1) a step of bringing the glass into contact with an inorganic salt composition including 70 mass % or more of potassium nitrate to perform ion exchange; (2) a step of bringing the glass having been ion-exchanged in step (1) into contact with an inorganic salt composition including 50 mass % or more of sodium nitrate to perform ion exchange; and (3) a step of bringing the glass having been ion-exchanged in step (2) into contact with an inorganic salt composition including 70 mass % or more of potassium nitrate to perform ion exchange.

What is claimed is: 
     
         1 : A method for producing a chemically strengthened glass, the method comprising
 (1) contacting a glass with an inorganic salt composition comprising 70 mass % or more of potassium nitrate to perform ion exchange;   (2) contacting the glass obtained in (1) with an inorganic salt composition comprising 50 mass % or more of sodium nitrate to perform ion exchange; and   (3) contacting the glass obtained in (2) with an inorganic salt composition comprising 70 mass % or more of potassium nitrate to perform ion exchange,   wherein the glass comprises, in mole percentage based on oxides, from 50 to 80% of SiO 2 , from 2 to 25% of Al 2 O 3 , from 0.1 to 20% of Li 2 O, from 0.1 to 18% of Na 2 O, from 0 to 10% of K 2 O, from 0 to 15% of MgO, from 0 to 5% of CaO, from 0 to 5% of P 2 O 5 , from 0 to 6% of B 2 O 3 , from 0 to 5% of Y 2 O 3 , and from 0 to 5% of ZrO 2 .   
     
     
         2 : The method of  claim 1 , satisfying at least one of the following (a1) to (a3):
 (a1) in (1), the contact between the glass and the inorganic salt composition is performed at 350 to 480° C. for 0.5 to 20 hours;   (a2) in (2), the contact between the glass and the inorganic salt composition is performed at 340 to 480° C. for 0.5 to 20 hours; and   (a3) in (3), the contact between the glass and the inorganic salt composition is performed at 350 to 480° C. for 0.5 to 20 hours.   
     
     
         3 : The method of  claim 1 , satisfying at least one of the following (b1) to (b3):
 (b1) the inorganic salt composition in (1) is an inorganic salt composition comprising 80 mass % or more of potassium nitrate;   (b2) the inorganic salt composition in (2) is an inorganic salt composition comprising 65 mass % or more of sodium nitrate; and   (b3) the inorganic salt composition in (3) is an inorganic salt composition comprising 80 mass % or more of potassium nitrate.   
     
     
         4 : The method of  claim 1 , satisfying at least one of the following (c1) to (c3):
 (c1) in (1), the contact between the glass and the inorganic salt composition is performed at 360 to 470° C.;   (c2) in (2), the contact between the glass and the inorganic salt composition is performed at 350 to 470° C.; and   (c3) in (3), the contact between the glass and the inorganic salt composition is performed at 360 to 470° C.   
     
     
         5 : The method of  claim 1 , satisfying at least one of the following (d1) to (d3):
 (d1) in (1), the contact between the glass and the inorganic salt composition is performed for 0.5 to 15 hours;   (d2) in (2), the contact between the glass and the inorganic salt composition is performed for 1 to 15 hours; and   (d3) in (3), the contact between the glass and the inorganic salt composition is performed for 0.5 to 15 hours.   
     
     
         6 : The method of  claim 1 , wherein:
 Na ion is ion-exchanged with K ion in (1);   Li ion is ion-exchanged with Na ion in (2); and   Na ion is ion-exchanged with K ion in (3).