Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Heterocyclic ring compound; a heterocyclic ring is one...
Patent
1997-05-23
1999-10-12
McAvoy, Ellen M.
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Heterocyclic ring compound; a heterocyclic ring is one...
508255, 508267, 508549, 508546, 428695, 252 6254, 544179, 546184, 546248, C07C24300, C10M10556
Patent
active
059654961
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a lubricant prepared by modifying terminals of fluorine-containing polyethers, perfluoroalkyl compounds or perfluoroalkenyl with organic free radicals, especially a lubricant for magnetic recording medium, and a magnetic recording medium comprising said lubricant.
The lubricant firmly adhered to a surface of base made of, in particular, carbon, amorphous carbon, graphite, ceramics, metals, etc. as a thin layer imparts improved lubricating properties to the base leading to excellent lubrication of a magnetic recording medium.
BACKGROUND ART
Improvement of magnetic recording density of magnetic recording media, such as tapes, cards, discs has been requested more and more leading to severe sliding conditions between a magnetic recording head and a magnetic face. Specifically, a decrease of distance between a magnetic recording head and a magnetic recording face, or an increase of sliding rate occurs leading to requirement of improved performance of lubricants applied to the surface of magnetic recording medium from the viewpoint of duration and utility.
Previously, for example, U.S. Pat. No. 3,715,378 discloses perfluoroethers as lubricants applied to magnetic recording media.
The perfluoropolyethers are excellent lubricants because of superior properties of heat-resistance, chemical inactivity and low vapor pressure. However, the perfluoropolyethers alone are inferior in adsorptivity to a medium which makes it difficult to employ the perfluoropolyethers by itself as a lubricant for magnetic recording medium.
Attempts of converting terminals of perfluoropolyethers into polar groups by the action of which perfluoropolyether lubricants were adhered to a base medium were carried out so as to improve an adsorptivity of the lubricants to the medium (see, U.S. Pat. No. 4,267,238; U.S. Pat. No. 4,268,556; and Japanese Unexamined Patent Publication No. 61-4727).
Lubricants comprising perfluoroalkylpolyethers having polar groups at terminals are adhered to a medium by the action of the polar groups and maintain lubricating properties by perfluoropolyoxy-alkylene chain elongated therefrom.
However, requests for significant improvement of magnetic recording density lead to higher requests for improvement of lubricating properties of lubricant for use in magnetic recording medium. Under these circumstances, even perfluoropolyethers with polar groups are not practically enough in lubricating properties and durability.
It is an object of the invention to provide a lubricant for magnetic recording medium imparting good lubricating properties to magnetic recording medium and a fluorine-containing compound useful as said lubricant.
DISCLOSURE OF THE INVENTION
The invention provides a fluorine-containing polyether compound represented by formula (1) or (1') --Y1--Z1 (1) --(Rf2)--(CF.sub.2).sub.x --(CH.sub.2).sub.y --{CHR--CH.sub.2 }.sub.z3 --Y3--Z3 (1') fluorine-containing polyether group, a perfluoroalkyl group or a perfluoroalkenyl group; Y1, Y2 and Y3 are the same or different and each represents a single bond, --O--, --COO-- or --CONH--; Rs are the same or different and each represents a hydrogen atom or a hydroxyl group provided that Y1, Y2 and Y3 represent --O-- when R is a hydroxyl group; Z1, Z2 and Z3 are a group containing an organic free radical in structure thereof; x and y are an integer of 0-10, respectively; z1, z2 and z3 are 0 or 1. The invention also provides a lubricant, a lubricant for magnetic recording medium and a magnetic recording medium comprising said fluorine-containing polyether compound.
The fluorine-containing polyether groups represented by Rf1 and Rf2 include groups represented by formulae (2) and (3): O).sub.l -- (2) --(CCCl.sub.2 CF.sub.2 CF.sub.2 O).sub.c --(CHFCF.sub.2 CF.sub.2 O).sub.d --(CFClCF.sub.2 CF.sub.2 O).sub.e --(CF.sub.2 CF.sub.2 CF.sub.2 O).sub.f --(3) integer, respectively and meet the expression 2<l+m+n<200; integer, respectively and meet the expressions 2<a+b+c+d+e+f<200, and, a+c+d+f>1.
Molecular weight of
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Honda Yoshitaka
Yamana Masayuki
Daikin Industries Ltd.
McAvoy Ellen M.
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