Display cover glass and display cover glass fabrication method

Abstract

The present invention provides a cover glass for a display, having high durability to slow cracking and strong abraded strength even though a compressive stress is large and a depth of a compressive stress layer is deep. The present invention relates to a cover glass for a display, in which a depth of a compressive stress layer (DOL) is 30 μm or more, a surface compressive stress is 300 MPa or more, a position (HW) at which a compressive stress is half of a value of the surface compressive stress is a position of 8 μm or more from a glass surface, and the depth of the compressive stress layer (DOL) and the position (HW) at which the compressive stress is half of the value of the surface compressive stress satisfy the following formula: 0.05≦ HW/DOL ≦0.23  (1).

1 : A cover glass for a display, wherein
 a depth of a compressive stress layer DOL is 50 μm or more,   a surface compressive stress CS is 300 MPa or more,   the cover glass has a HW/DOL ratio of 0.23 or less, where HW is a position at which a compressive stress is half of the surface compressive stress,   the cover glass has a three-point bending strength of more than 43 MPa, and   the cover glass has a slow cracking height of 35 cm or more measured using a stainless steel sphere having a weight of 4 g, or a slow cracking height of 7.4 cm or more measured using a stainless steel sphere having a weight of 28 g.   
     
     
         2 - 6 . (canceled) 
     
     
         7 : The cover glass according to  claim 1 , wherein the HW/DOL ratio is 0.05 or more. 
     
     
         8 : The cover glass according to  claim 1 , wherein the surface compressive stress CS is 500 MPa or more. 
     
     
         9 : The cover glass according to  claim 1 , wherein the cover glass has a slow cracking height greater than a glass having the same CS×DOL value and a HW/DOL ratio of greater than 0.23. 
     
     
         10 : The cover glass according to  claim 1 , wherein the cover glass has a composition of 50 to 80% of SiO 2 , 2 to 25% of Al 2 O 3 , 0 to 10% of Li 2 O, 0 to 18% of Na 2 O, 0 to 10% of K 2 O, 0 to 15% of MgO, 0 to 5% of CaO, and 0 to 5% of ZrO 2 , in terms of mol %. 
     
     
         11 : The cover glass according to  claim 1 , wherein, in terms of mol %,
 the cover glass has a composition of 61 to 72% of SiO 2 , 8 to 17% of Al 2 O 3 , 6 to 18% of Li 2 O, 2 to 15% of Na 2 O, 0 to 8% of K 2 O, 0 to 6% of MgO, 0 to 6% of CaO, 0 to 4% of TiO 2 , and 0 to 2.5% of ZrO 2 ,   a total content of Li 2 O, Na 2 O, and K 2 O is 15 to 25%,   a ratio Li 2 O/(Li 2 O+Na 2 O+K 2 O) is 0.35 to 0.8, and   a total content of MgO and CaO is 0 to 9%.