| 摘要 |
A lubricant which does not splash easily and has an improved property of slidableness, and a magnetic disk using the lubricant are provided. A magnetic disk apparatus featuring a prolonged service life of a stable operation and an excellent record reproduction property is provided by installing the above magnetic disk. The lubricant of the invention contains perfluoropolyether expressed by the following general formula, in which a component of its molecular weights less than 1000 is smaller than 10 wt. %, a component of its molecular weights not less than 7000 is smaller than 15 wt. %, a ratio between a weight average molecular weight and a numeric average molecular weight is 1.5 or less, and a substitution ratio of its terminal functional group is not less than 90%:where R1 and R2 are univalent organic groups, m and n are positive integers. Further for the magnetic disk which rotates at a speed of 10000 rpm or more, a lubricant containing a perfluoropolyether expressed by the following general formula is used, in which its numeric average molecular weight is not less than 5500, a component of molecular weights less than 3000 is 15 wt. % or less, a ratio between its weight average molecular weight and its numeric average molecular weight is 1.5 or less, and a substitution ratio of its terminal functional group is not less than 90%:where m and n are positive integers.
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