Method of manufacturing a magnetic disk
View Patent ↗On manufacturing a magnetic disk having at least a magnetic layer ( 60 ), a protective layer ( 70 ), and a lubricating layer ( 80 ) formed in this order over a substrate ( 10 ), the lubricating layer is formed by using a coating solution in which a perfluoropolyether compound having a perfluoropolyether main chain and a hydroxyl group in a structure thereof is dispersed and dissolved in a fluorine-based solvent having a boiling point of 90° C. or more.
1. A method of manufacturing a magnetic disk comprising at least a magnetic layer, a protective layer, and a lubricating layer formed in this order over a substrate, wherein the lubricating layer is formed by:
first dispersing and dissolving a perfluoropolyether compound comprising a perfluoropolyether main chain and four or more hydroxyl groups in a structure thereof in a fluorine-based solvent having a boiling point of 90° C. or more to obtain a coating solution;
heating the coating solution to a temperature in a range of 45° C. to 60° C. such that the temperature of the coating solution is lower than a boiling point of the solvent and the perfluoropolyether compound is dissolved in the solvent; and then
coating the magnetic disk having the magnetic layer and the protective layer with the coating solution having the temperature of 45° C. to 60° C. to form the lubricating layer by dipping and immersing the magnetic disk having the magnetic layer and the protective layer into the coating solution having the temperature of 45° C. to 60° C., and then lifting the magnetic disk out of the coating solution to obtain the lubricating layer uniformly coated on the protective layer.
2. The method according to claim 1 , wherein a number-average molecular weight of the perfluoropolyether compound included in the lubricating layer is in a range of 1,000 to 10,000.
3. The method according to claim 1 , wherein the protective layer is a carbon-based protective layer formed by a plasma CVD method.
4. The method according to claim 3 , wherein the protective layer comprises nitrogen in an area adjacent to the lubricating layer.
5. The method according to claim 1 , wherein the magnetic disk is a magnetic disk adapted to be mounted in a magnetic disk apparatus of a load/unload system as a start/stop mechanism and to be used with a head flying height of 5 nm or less.
6. The method according to claim 1 , wherein the fluorine-based solvent is represented by either formula (1) or formula (2):
C 6 F 13 OCH 3 (1)
C 3 HF 6 —CH(CH 3 )O—C 3 HF 6 (2).