| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a glass substrate for a recording medium excellent in fluttering characteristics and surface smoothness. <P>SOLUTION: The glass substrate for a recording medium is obtained by coating front-back both sides of an inner layer with a surface layer. The inner layer has a glass composition containing ≥30 mass% of at least one of SiO<SB POS="POST">2</SB>and P<SB POS="POST">2</SB>O<SB POS="POST">5</SB>, wherein a total amount of specific alkali components consisting of Li<SB POS="POST">2</SB>O, Na<SB POS="POST">2</SB>O and K<SB POS="POST">2</SB>O is 0.1-16 mass%. The surface layer has a glass composition containing ≥30 mass% of at least one of SiO<SB POS="POST">2</SB>and P<SB POS="POST">2</SB>O<SB POS="POST">5</SB>, wherein a total amount of specific alkali components consisting of Li<SB POS="POST">2</SB>O, Na<SB POS="POST">2</SB>O and K<SB POS="POST">2</SB>O is 0-0.1 mass%. The difference between the total amount of the specific alkali components in the inner layer and the total amount of the specific alkali components in the surface layer is ≥0.1 mass%. <P>COPYRIGHT: (C)2012,JPO&INPIT |
