Ultra-low profile multidentate lubricant for use as a sub-nanometer thick lubricant layer for magnetic media

Patent metadata

Field	Value
Publication number	US-9466322-B2
Application number	US-201414185153-A
Country	US
Kind code	B2
Filing date	Feb 20, 2014
Priority date	Feb 20, 2014
Publication date	Oct 11, 2016
Grant date	Oct 11, 2016

Abstract

According to one embodiment, a lubricant includes a multidentate perfluoropolyether having a chemical structure of: R e —R z —R i —R z —R i —R z —R e , where R z includes at least one perfluoroethyl ether unit, and where R e and R i each include at least one functional group configured to attach to a surface. According to another embodiment, the aforementioned lubricant may be suitable for use in a sub-nanometer thick lubricant layer for various applications, and particularly useful for magnetic recording media.

First claim

What is claimed is:

1. A lubricant, comprising:
a multidentate perfluoropolyether according to the formula:
R e —R z —R i —R z —R i —R z —R e ,

wherein each R z segment includes at least one perfluoroethyl ether unit,
wherein each R e and R i segment includes at least one functional group configured to attach to a surface,
wherein the R z segments have the same structure as one another.

2. The lubricant as recited in claim 1 , wherein the least one perfluoroethyl ether unit is represented by:
—(CF 2 CF 2 O) n —, wherein n is an integer greater than zero.

3. The lubricant as recited in claim 2 , wherein n is 2.

4. The lubricant as recited in claim 1 , wherein each R z segment has a molecular weight between about 300 amu to about 1350 amu.

5. The lubricant as recited in claim 1 , wherein the at least one functional group is selected from the group consisting of: a hydroxyl group, a piperonyl group, an amine group, a carboxylic acid, a phosphazene group, and a combination thereof.

6. The lubricant as recited in claim 1 , wherein the multidentate perfluoropolyether includes eight functional groups configured to attach to a surface.

7. The lubricant as recited in claim 1 , wherein each R z segment is represented by:
—OCH 2 CF 2 O—(CF 2 CF 2 O) n —CF 2 CH 2 O—, wherein n is an integer ranging from 1 to 10.

8. The lubricant as recited in claim 1 , wherein each R e segment is represented by:

wherein each X is independently selected from the group consisting of: a hydroxyl group, a piperonyl group, an amine group, a phosphazene group, and a combination thereof.

9. The lubricant as recited in claim 1 , wherein each R i segment is represented by:

wherein each X is independently selected from the group consisting of: a hydroxyl group, a piperonyl group, an amine group, a phosphazene group, and a combination thereof.

10. The lubricant as recited in claim 1 , wherein the R e segments have the same structure as one another.

11. The lubricant as recited in claim 1 , wherein the R i segments have the same structure as one another.

12. A method for forming a magnetic medium, the method comprising:
forming a magnetic recording layer above a non-magnetic substrate;
forming a protective overcoat above the magnetic recording layer; and
forming a lubricant layer above the protective overcoat,
wherein the lubricant layer comprises the multidentate perfluoropolyether as recited in claim 1 .

13. The method as recited in claim 12 , wherein formation of the lubricant layer over the protective overcoat comprises dipping the magnetic medium having the protective overcoat thereon into a lubricant bath, wherein the lubricant bath comprises the multidentate perfluoropolyether and a solvent.

14. The method as recited in claim 12 , wherein a concentration of the multidentate perfluoropolyether in the lubricant bath is between about 0.1 g/L to about 0.2 g/L.

15. A lubricant, comprising:
a multidentate perfluoropolyether according to the formula:
R e —R z —R i —R z —R i —R z —R e ,

wherein R z includes at least one perfluoroethyl ether unit,

wherein R e and R i each include at least one functional group configured to attach to a surface,
wherein the multidentate perfluoropolyether includes eight functional groups configured to attach to a surface,
wherein the eight functional groups are hydroxyl groups.

16. A magnetic medium, comprising:
a magnetic recording layer positioned above a non-magnetic substrate;
a protective overcoat positioned above the magnetic recording layer; and
a lubricant layer positioned above the protective overcoat, the lubricant layer comprising a multidentate perfluoropolyether according to the formula:
R e —R z —R i —R z —R i —R z —R e ,

wherein R z includes at least one perfluoroethyl ether unit,
wherein R e and R i each include at least one functional group configured to attach to a surface,
wherein the multidentate perfluoropolyether includes eight functional groups configured to attach to a surface, wherein the eight functional groups are hydroxyl groups.

17. The magnetic medium as recited in claim 16 , wherein the least one perfluoroethyl ether unit is represented by:
—(CF 2 CF 2 O) n —, wherein n is an integer greater than zero.

18. The magnetic medium as recited in claim 16 , wherein R z is represented by:
—OCH 2 CF 2 O—(CF 2 CF 2 O) n —CF 2 CH 2 O—, wherein n is an integer ranging from 1 to 10.

19. The magnetic medium as recited in claim 16 , wherein R e is represented by:

wherein each X corresponds to one of the hydroxyl groups.

20. The magnetic medium as recited in claim 16 , wherein R i is represented by:

wherein each X corresponds to one of the hydroxyl groups.

21. The magnetic medium as recited in claim 16 , wherein a thickness of the lubricant layer is between 7 Å to 8 Å.

22. The magnetic medium as recited in claim 16 , wherein the multidentate perfluoropolyether exhibits a bonded percentage of at least 75%.

23. The magnetic medium as recited in claim 16 , wherein the lubricant layer having a thickness of between 7 Å to 8 Å includes less contaminants than an otherwise identical layer comprised of Z-Tetraol Multidentate (ZTMD).

24. A magnetic data storage system, comprising:
at least one magnetic head;
the magnetic recording medium as recited in claim 16 ;
a drive mechanism for passing the magnetic recording medium over the at least one magnetic head; and
a controller electrically coupled to the at least one magnetic head for controlling operation of the at least one magnetic head.

Assignees

• HGST Netherlands BV

Inventors

• Deng Hong
• Guo Xing-Cai
• Marchon Bruno
• Pathem Bala K
• Waltman Robert

Classifications

• G11B5/8408 Primary

  protecting the magnetic layer · CPC title

• G11B5/725 Primary

  containing a lubricant {, e.g. organic compounds (inorganic carbon protective coating G11B5/727)} · CPC title

• C10M145/24

  Polyethers · CPC title

• G11B5/7257 Primary

  Perfluoropolyether lubricant · CPC title