Magnetic disk and manufacturing method thereof
AssigneesWD Media (Singapore), LLC, Singapore Pte. Ltd.
InventorsKoichi Shimokawa, Katsushi Hamakubo, Kae Itoh
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Abstract
A magnetic disk having at least a magnetic layer, a carbon protective layer, and a lubrication layer sequentially provided on a substrate. The lubrication layer is a film formed by a lubricant that contains two types of compounds having a perfluoropolyether main chain in the structure, a molecular weight distribution of the two types in total being within a range of 1 to 1.2. The two types of compounds include a compound a having a hydroxyl group at the end and a compound b having a number average molecular weight smaller than the number average molecular weight of the compound a and not more than 1500. A content of the compound b in the two types of compounds is not more than 10%.
Claims9
A magnetic disk comprising:
- a substrate;
- at least a magnetic layer, a protective layer, and a lubrication layer sequentially provided on the substrate,
- wherein the lubrication layer is a film formed by a lubricant that contains two types of compounds each having a perfluoropolyether main chain in its structure,
- wherein the two types of compounds includes a compound a having two or four hydroxyl groups in total at ends of a molecule of the compound a and a compound b, and wherein the compound b has a number average molecular weight that is smaller than the number average molecular weight of the compound a and not more than 1500;
- wherein a molecular weight distribution of the two types of compounds in total is within a range of 1 to 1.2;
- wherein a content of the compound b in the two types of compounds is not more than 10%;
- and
- wherein the compound b is selected from the group consisting of the following compounds represented by formula (1), formula (2), formula (3) and formula (4):
- wherein Rf represents —(OC2F4)m(OCF2)n- and m and n each represents an integer of not less than 1.
A manufacturing method of a magnetic disk having at least a magnetic layer, a protective layer, and a lubrication layer sequentially provided on a substrate, characterized in that
- said lubrication layer is formed by:
- performing molecular distillation of a lubricant containing
- two types of compounds each having a perfluoropolyether main chain in its structure,
- wherein the two types of compounds includes a compound a having two or four hydroxyl groups in total at ends of a molecule of the compound a and a compound b, and wherein the compound b has a number average molecular weight that is smaller than the number average molecular weight of the compound a and not more than 1500;
- wherein a molecular weight distribution of the two types of compounds in total is within a range of 1 to 1.2;
- wherein a content of the compound b in the two types of compounds is not more than 10%;
- and
- wherein the compound b is selected from the group consisting of the following compounds represented by formula (1), formula (2), formula (3) and formula (4):
- wherein Rf represents —(OC2F4)m(OCF2)n- and m and n each represents an integer of not less than 1;
- and
- forming a film of the lubricant on said protective layer.
Dependencies are inferred from the claim text.