Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1989-02-15
1992-10-20
Seidleck, James J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525196, 525244, 525258, 5253275, 525282, 525301, 525384, 526271, 524600, C08F27904, C08F27906, C08F 842
Patent
active
051570831
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a composition containing a novel rubber-like polymer and more particularly it relates to a rubber composition which has excellent strength characteristics while retaining a very good balance in performance characteristics such as oil resistance, heat resistance, weather resistance, and low-temperature resistance.
BACKGROUND ART
Rubber obtained by hydrogenating acrylonitrile-butadiene copolymer rubber (NBR) is well known as an excellent rubber having a good balance among oil resistance, heat resistance, weather resistance, low-temperature resistance and strength. Since hydrogenated NBR has such excellent characteristics, it is used for purposes requiring oil resistance, heat resistance and strength, for example, it is used in toothed transmission belts (timing belts) for automobiles.
However, also in such applications, from the viewpoint of long-term service, a high strength at ordinary temperature and high temperatures is required, and in order to insure efficient power transmission it has been desirable to improve the insufficient low-extension stress (e.g. 50% tension stress) at high temperatures which is a defect of hydrogenated NBR.
On the other hand, it is known that the strength of NBR can be improved by further copolymerizing a carboxyl-group-containing monomer. However, although excellent in strength at ordinary temperature and high temperatures, a hydride of the NBR obtained by copolymerizing a carboxyl-group-containing monomer is not much different from hydrogenated NBR in low-extension stress at high temperature, namely, it is not improved in low-extension stress.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a composition of a highly saturated nitrile-group-containing rubber, which has not only an improved strength at ordinary temperature and high temperatures but also an improved low-extension stress at high temperatures.
The present inventors have devoted themselves to research and consequently found that the above object can be achieved by using a rubber obtained by adding maleic anhydride or the like to a highly saturated nitrile-group-containing rubber, whereby the present invention has been accomplished.
Thus, according to the present invention, there is provided a rubber composition comprising a polymer obtained by adding maleic anhydride or a derivative thereof to a nitrile-group-containing highly saturated polymer rubber having an iodine value of 80 or less.
The nitrile-group-containing high saturated polymer rubber used in this invention includes rubbers obtained by hydrogenating the conjugated diene unit portions of unsaturated nitrile-conjugated diene copolymer rubbers, unsaturated nitrile-conjugated diene-ethylenic unsaturated monomer ternary copolymer rubbers, rubbers obtained by hydrogenating the conjugated diene unit portions of the ternary copolymer rubbers, unsaturated nitrile-ethylenic unsaturated monomer copolymer rubbers, etc. These nitrile-group-containing highly saturated polymer rubbers can be obtained by a conventional polymerization method and a conventional hydrogenation method, but needless to say, a method for producing said rubber is not critical in the present invention. Although not critical, the content of unsaturated nitrile in the nitrile-group-containing highly saturated polymer rubber is usually in the range of 10 to 60% by weight.
Examples of monomers used for producing nitrile-group-containing highly saturated polymer rubbers described above are given below.
The unsaturated nitriles include acrylonitrile, methacrylonitrile, etc. The conjugated dienes, include 1,3-butadiene, 2,3-dimethylbutadiene, isoprene, 1,3-pentadiene, etc. The ethylenic unsaturated monomers include, for example, vinyl aromatic compounds such as styrene, chlorostyrene, p-t-butylstyrene, chloromethylstyrene, and the like; esters of unsaturated carboxylic acids, such as methyl acrylate, 2-ethylhexyl acrylate, and the like; alkoxyalkyl esters of the aforesaid unsaturated carboxylic acids, such as methoxymeth
REFERENCES:
patent: 3385912 (1968-05-01), Harris
patent: 4033888 (1977-07-01), Kiorsky
patent: 4332918 (1982-06-01), Fukahori
patent: 4560729 (1984-10-01), Watanabe et al.
patent: 4786675 (1988-11-01), Iwata et al.
Aimura Yoshiaki
Aonuma Mitsuyoshi
Sakakida Hiroshi
Jagannathan Vasu S.
Nippon Zeon Co Ltd
Seidleck James J.
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