Patent ID: 7838136

Claim:
An information recording media, which comprises a glass substrate for a magnetic disk and a magnetic recording layer formed thereon, wherein the glass substrate comprises, as represented by mol % based on oxide; from 61 to 66% of SiO 2 , from 11.5 to 17% of Al 2 O 3 , from 8 to 16% of Li 2 O, from 2 to 8% of Na 2 O, from 2.5 to 8% of K 2 O, from 0 to 6% of MgO, from 0 to 4% of TiO 2 , from 0 to 3% of ZrO 2 , and from 0 to 1% of at least one alkaline earth metal oxide selected from the group consisting of CaO, SrO and BaO; provided that Al 2 O 3 +MgO+TiO 2 is at least 12%, and Li 2 O+Na 2 O+K 2 O is from 16 to 23%, and said glass comprises less than 1% of B 2 O 3 , wherein when the glass is left under steam atmosphere at 120° C. at 0.2 MPa for 20 hours, and the amount of Li, the amount of Na and the amount of K, which precipitate on a surface of the glass are represented as C Li , C Na , C K , respectively, C Na is at most 0.7 nmol/cm 2 , and C Li +C Na +C K is at most 3.5 nmol/cm 2 .