Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1996-09-23
1998-07-21
Szekely, Peter A.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
524311, 524312, 524313, 524315, 524306, C08K 510, C08K 5101, C08K 5103
Patent
active
057836191
DESCRIPTION:
BRIEF SUMMARY
This Application is a 371 of PCT/U.S. 95/03202 Mar. 31, 1995.
DETAILED DESCRIPTION OF THE INVENTION
The present invention concerns a polyacetal resin composition with excellent slidability and abrasion resistance appropriately used for sliding parts and plastic sliding parts. More specifically, it concerns a polyacetal resin composition that makes it possible to propose sliding parts with excellent slidability and abrasion resistance even when the material of the partner sliding part is plastic or metal when used as sliding parts, and sliding parts that employ this composition.
Polyacetal resin is a resin that has excellent mechanical properties and heat resistance, especially abrasion resistance, and is used for sliding parts in a wide range of fields.
Methods of adding inorganic solid lubricants such as molybdenum disulfide and graphite, liquid, or semisolid lubricants such as petroleum lubricants, synthetic lubricants, aliphatic alcohols or esters thereof, and polyolefin resin micropowders with a molecular weight of at least 500,000 are known in order to further improve the abrasion resistance of polyacetal resin.
However, even if the partner sliding part is made of plastic, the abrasion resistance varies greatly depending on the type of plastic. Even though there are good properties for partner sliding parts made of certain types of plastics, the problem is that the abrasion resistance is poor to partner sliding parts made from other plastics. The lubricant had to be selected by taking into consideration the material of the partner sliding parts with which contact was to be made.
Nonetheless, gears, rollers, cams, switches, etc., made from many types of plastic materials, beginning with polyacetal, are used in electrical and electronic equipment, especially office machinery such as audio machines, copy machines, and printers. For example, gears are designed so that the speed of rotation is regulated by the connection of several gears. There are consequently cases in which gears made of polyacetal are meshed with gears made of polyacetal or other plastics. Consequently, the development of a polyacetal resin composition that makes it possible to provide excellent slidability and abrasion resistance even without selecting the lubricant by taking into consideration the type of plastic was desired.
A polyacetal resin composition with a density of no more than 0.93 g/cm.sup.3 that contains no more than 15% by weight of polyolefin resin with a weight mean molecular weight of no more than 500,000 was consequently developed (Japanese Patent Application No. Hei 5-143322) as a polyacetal resin composition with excellent abrasion resistance regardless of the type of plastic from which the partner sliding parts are made.
Nonetheless, metal shafts are inserted in the inner diameter of gears. Good slidability and abrasion resistance between polyacetal and metal are therefore required simultaneously in addition to the good slidability and abrasion resistance between polyacetal and other plastics. Even though there is a certain level of good slidability and abrasion resistance when the partner sliding parts are made of metal when one uses a polyacetal resin composition with a density of no more than 0.93 g/cm.sup.3 that contains no more than 15% by weight of polyolefin resin with a weight mean molecular weight of no more than 500,000, the problem was that abrasion developed with long term operation and noises such as squeaking were produced by abrasion when used under high load or high sliding speed conditions.
International Patent Application WO 93/11206 of E. I. du Pont de Nemours and Company discloses lubricated polyacetal compositions containing at least one lubricant and a copolymer of the general formula E/X/Y, wherein E is ethylene; X is methyl, ethyl, or butyl acrylate; and Y is glycidyl acrylate or methacrylate, or glycidyl vinyl ether.
European Patent Application EP-A-354 802 of Polyplastics Co., Ltd. discloses polyacetal compositiins and sliding member, wherein the compositions comprises 0.5 to 40 parts b
REFERENCES:
patent: 4041002 (1977-08-01), Aboshi et al.
patent: 5106896 (1992-04-01), Endo et al.
patent: 5191006 (1993-03-01), Matsumoto et al.
patent: 5346737 (1994-09-01), Takahashi et al.
patent: 5559180 (1996-09-01), Takahashi et al.
E. I. Du Pont de Nemours and Company
Szekely Peter A.
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