Magnetic disk and manufacturing method thereof
View Patent ↗A magnetic disk of is provided, the magnetic disk having at least a magnetic layer, a carbon protective layer, and a lubrication layer sequentially provided on a substrate. In an embodiment, the lubrication layer a film formed by a lubricant having a perfluoropolyether compound A having a perfluoropolyether main chain in the structure and also having a hydroxyl group at the end and a compound C obtained from a reaction between a compound B expressed by: [Chemical formula 1] CF 3 (—O—C 2 F 4 )m-(O—CF 2 )n-OCF 3 [m and n in the formula are natural numbers.] and aluminum oxide.
1. A magnetic disk comprising a magnetic layer, a protective layer, and a lubrication layer sequentially provided on a substrate, wherein:
said lubrication layer comprises a lubricant comprising:
a compound A comprising a perfluoropolyether main chain and a hydroxyl terminal group, wherein the compound A has a number average molecular weight of 1000 to 10,000; and
a compound C, wherein the compound C is obtained from a reaction between aluminum oxide and a compound B expressed by formula I:
CF 3 (—O—C 2 F 4 ) m —(O—CF 2 ) n —OCF 3 formula I
wherein m and n are natural numbers not less than 1;
wherein:
the aluminum oxide is removed after the reaction, and
the compound C consists of fragments resulting from a cleavage of a carbon-carbon bond in the compound B and has a number average molecular weight less than compound A and not more than 1500.
2. The magnetic disk according to claim 1 , wherein the compound A has a number average molecular weight of 1000 to 6000.
3. The magnetic disk according to claim 1 , wherein said protective layer is a carbon protective layer.
4. The magnetic disk according to claim 1 , wherein the magnetic disk is a magnetic disk mounted on a Load-Unload method magnetic disk device.
5. The magnetic disk according to claim 1 , wherein said compound A and said compound C have a weight ratio of 8:2 to 9:1.
6. The magnetic disk according to claim 1 , wherein said compound B has a molecular weight of 3000 to 7000.
7. The magnetic disk according to claim 1 , wherein the lubrication layer has a film thickness of 5 to 20 Å.
8. The magnetic disk according to claim 1 , wherein the protective layer has a film thickness of 20 to 70 Å.
9. The magnetic disk according to claim 1 , wherein the compound A has two terminal hydroxyl groups.
10. The magnetic disk according to claim 1 , wherein the compound A has a chemical formula:
wherein p and q are natural numbers not less than 1.
11. The magnetic disk according to claim 1 , wherein the compound C has a number average molecular weight of 500 to 1500.