Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic -co- compound
Reexamination Certificate
1998-03-30
2001-09-11
Medley, Margaret (Department: 1721)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic -co- compound
C508S524000, C508S588000, C360S097010
Reexamination Certificate
active
06288014
ABSTRACT:
FIELD OF THE INVENTION
The field of this invention is lubricants for use in information storage systems. More particularly, the invention pertains to information storage systems employing a lubricant including perflouroacrylate ester polymer and having improved anti-wear properties.
BACKGROUND OF THE INVENTION
In information storage systems, such as disk drives found in personal computers and other data processing devices, a rigid magnetic storage medium is moved relative to a read/write head to provide information introduction to and/or retrieval from the magnetic storage medium. The magnetic storage medium (also referred to as a “disk” or “media”) are typically comprised of a rigid substrate, an underlayer, a magnetic layer and a carbon layer atop the magnetic layer. In the design of such devices, it is most desirable from a magnetic standpoint to have the read/write head continually touch the surface of the disk during movement to maximize the signal quality. However, the magnetic benefits of such a design are outweighed by the wear and material interactions caused by such a contact arrangement, and such interactions lead to poor system reliability and performance.
To reduce the wear and material interactions on the surface of the disk, a lubricant is commonly disposed on the surface of the disk. A variety of lubricants are used by the industry. One group of commonly used lubricants are perfluoropolyethers (PFPE). There is a continued interest in the development of improved lubricants. This is particularly the case as storage system designs strive for lower “fly heights”. The fly height is known in the art to define a certain minimal distance maintained between the head and the disk during movement. Lower fly heights increase the need for good quality lubricants.
Prior art lubricants have been found to be subject to a number of limitations. For example, lubricants may be insoluble or otherwise incompatible with other fluids such as solvents. Also, known lubricants may not be thermally stable. To increase the life of the lubricant, various additives may be added to the lubricant. For example, anti-wear additives may be added to increase the wear resistance of the lubricating fluid. In this case, the solubility, stability and compatibility of the additive must also be evaluated. Moreover, by-products given off during decomposition of the lubricant and/or additives can be problematic.
Thus, there is interest in the development of improved lubricants and additives that exhibit good lubricating properties including wear resistance, are thermally stable, and soluble or compatible with other fluids.
OBJECTS AND SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an information storage system employing a lubricant exhibiting desirable lubricating properties.
Another object of the present invention is to provide a lubricant having improved wear resistance properties.
More particularly, it is an object of the present invention to provide a lubricant including a perflouroacrylate ester polymer on the surface of a disk in an information storage system.
Another object of the present invention is to provide a lubricant composition comprised of a mixture of perfluoro-polyether and perflouroacrylate ester polymer.
These and other objects and advantages are achieved by the invention herein where an information storage system comprising a perfluoroacrylate ester polymer lubricant on the surface of a rigid storage medium is provided. In one embodiment of the subject invention, the lubricant includes a perfluoroacrylate ester homopolymer having a repeat unit of the general structure:
where R is a perfluoro alkyl chain, linear or branched and containing 1 to 18 carbon atoms; and X is selected from the group consisting of H, CH
3
, CF
3
or C(CF
3
)
3
.
In an alternative embodiment of the present invention the lubricant includes a perfluoroacrylate ester copolymer having a repeat unit of the structure:
wherein Rf is a perfluoro alkyl chain, linear or branched and containing 1 to 18 carbon atoms; and X is selected from the group consisting of H, CH
3
, CF
3
or C(CF
3
)
3
.
In a further alternative embodiment, the lubricant composition is provided comprising a mixture of perfluoro-polyether and perflouroacrylate ester polymer.
REFERENCES:
patent: 5066409 (1991-11-01), Nader
patent: 5099055 (1992-03-01), Kar et al.
patent: 5118431 (1992-06-01), Nader
patent: 5124060 (1992-06-01), Yokouchi et al.
patent: 5131674 (1992-07-01), Tokui
patent: 5194652 (1993-03-01), Nader
patent: 5230964 (1993-07-01), Kar et al.
patent: 5494596 (1996-02-01), Law et al.
patent: 5624713 (1997-04-01), Ramer
patent: 5677051 (1997-10-01), Ueda
Medley Margaret
Seagate Technology LLC
Thomason Moser & Patterson LLP
Toomer Cephia D.
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