Lubricant

Abstract

A lubricant in the form of lubricating oil or grease, for use in contact with graphite or molybdenum disulfide or in contact with aluminum materials, which comprises a perfluoropolyether oil free from (CF₂O)_n groups as a repeat unit of polymer and having a kinetic viscosity at 40° C. of 50-1,500 mm²/sec., as a base oil, where F(CF₂CF₂CF₂O)_mC₂F₅ or RfO[CF(CF₃)CF₂O]_p(CF₂CF₂O)_qRf′ s used as the perfluoropolyether base oil. The lubricant undergoes no considerable deterioration of high-temperature characteristics (high-temperature durability), even if used in various uses as mentioned above, and also has distinguished low-temperature characteristics when the base oil has a kinetic viscosity of 50-250 mm²/sec.

Description

TECHNICAL FIELD[0001]The present invention relates to a lubricant, and more particularly to a lubricant comprising a lubricating oil or a grease for use in contact with graphite or molybdenum disulfide such as sintered, oil-impregnated bearings containing graphite or molybdenum disulfide or for use in contact with aluminum materials such as sliding members, etc., formed from aluminum materials.BACKGROUND ART[0002]Sintered, oil-impregnated bearings comprises porous bodies made compression of several kinds of solid powder obtained by adding solid lubricants such as graphite, molybdenum disulfide, carbon black, etc. to metal powders such as iron, copper, tin, zinc, etc. The sintered, oil-impregnated bearings can be used without any addition of oil owing to the self-lubrication action of a small amount of initially impregnated lubricant. Thus, it is important for the life of bearings that the a sufficient amount of lubricant can be retained in the bearings and can be stably used for a l...

AI Technical Summary

Benefits of technology

[0009]Perfluoropolyether oils undergo dramatically deterioration of the high-temperature characteristics (high-temperature durability) not only due to the structure of perfluoropolyether oils, but also due to contact with graphite or molybdenum disulfide used as one component in the sintered, oil-impregnated bearings. The present invention provides a lubricant free from considerable deterioration of high-temperature characteristics when used in contact with graphite or molybdenum disulfide such as the sintered, oil-impregnated bearings, etc. containing graphite or molybdenum disulfide, or in contact with metallic parts such as ball bearings, etc. containing graphite or molybdenum disulfide. Cases of the lubricant as used in contact with metallic parts include those used in atmospheres where the graphite or molybdenum disulfide prevails as scattered particles or as contaminants, for example, cases in contact with graphite or molybdenum disulfide coming from motor parts such as brushes, shafts, etc. The atmospheres where the graphite or molybdenum disulfide prevails as scattered particles or as contaminants are not to be restricted to the afore-mentioned cases.

[0010]The perfluoropolyether oils having a kinematic viscosity at 40° C. of 50-1,500 mm2 / sec. can maintain the volatility and stability for a long time, even if used at higher temperature more than 150° C. in the presence of a solid lubricant such as graphite, molybdenum disulfide, etc., thereby attaining a longer life of parts to be used. Particularly, perfluoropolyether oils having a kinematic viscosity of 50-250 mm2 / sec., preferably 65-200 mm2 / sec., have distinguished low-temperature characteristics as well.

[0011]The present lubricant can be used in any mode of sliding including revolution, reciprocation, slipping, and oscillation, for example, as sintered, oil-impregnated bearing or bushes containing graphite or molybdenum disulfide in automobile uses fuel injectors including units for controlling rates of idle revolution, units for recycling an exhaust gas, units for electronic throttle controlling, etc., and uses such as those requiring a heat resistance, a low-temperature resistance and a load resistance, typically hub units, traction motors, alternators, etc. or in those requiring abrasion resistance or a low friction characteristics, typically power transmission units, power wind motors, wipers, etc.; in information system uses requiring a high speed, a low friction coefficient, a low outgassing capacity, etc., typically hard disc drives, flexible disc memory devices, compact disc drives, photomagnetic disc drives, etc.; business machine uses, typically LBP scanner motors, etc.; and motor uses such as domestic electric appliances, sound equipment, etc., used in the high-temperature circumstances, etc. The present lubricant can be also effectively used in atmospheres where graphite or molybdenum disulfide comes into contact with the lubricant directly or through the contaminant prevailing there.

[0012]The high-temperature characteristics (high-temperature durability) of perfluoropolyether oils are drastically lowered also when used in contact with aluminum materials including aluminum material as sliding members, but the present lubricant never undergoes considerable deterioration of high-temperature characteristics, even when used in such a case as above. That is, the present lubricant can maintain the volatility or stability for a long time and can show a lubricability in various sliding operations, even if used in the presence of aluminum materials at higher temperature more than 150° C. or 200° C., thereby attaining an extremely longer life of parts to be used.

[0013]Besides such various uses as mentioned above, the present lubricant can be used also in bearings or bushes of heated rolls used in plastics-processing machines, business machines, and copiers, and those of chains, etc. used in construction machines, machine tools, electrically driven tools, machines for printing, book-binding and paper processing, or their parts, and also can be used in lubrication of contacts between sliding members of ball-and-roller bearings, plain bearings, sintered bearings, gears, valves, cocks, oil seals, rolls, electric contacts, etc.

Problems solved by technology

Lubricating oil compositions comprising a perfluoropolyether oil as a base oil have been so far used in such situations, and have been inevitably brought into and kept with contact with some kinds of metals or solid lubricants having a very large surface area, so even the perfluoropolyether oils fail to maintain stable high-temperature characteristics, depending on their structures.

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