Magnetic disk and manufacturing method thereof

Patent metadata

Field	Value
Publication number	US-9984715-B2
Application number	US-201514930229-A
Country	US
Kind code	B2
Filing date	Nov 2, 2015
Priority date	Sep 30, 2008
Publication date	May 29, 2018
Grant date	May 29, 2018

Abstract

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.

First claim

The invention claimed is:

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.

Assignees

• Wd Media Llc

Inventors

• Shimokawa Koichi
• Hamakubo Katsushi
• Itoh Kae

Classifications

• C10M177/00

  Special methods of preparation of lubricating compositions; Chemical modification by after-treatment of components or of the whole of a lubricating composition, not covered by other classes · CPC title

• C10N2080/00

  Special pretreatment of the material to be lubricated, e.g. phosphatising or chromatising of a metal · CPC title

• C10N2040/18

  in connection with recordings on magnetic tape or disc · CPC title

• G11B5/8408

  protecting the magnetic layer · CPC title

• C10M107/38 Primary

  containing halogen · CPC title