Mitsui Chemicals, Inc.

Masao Kunizane

Masaaki Kawasaki

Tetsuo Tojo

Yoshiharu Kikuchi

Kotaro Ichino

Takashi Hakuta

Hiroki Ebata

Taku Koda

Mitsunao Arino

Takayuki Kajihara

Shuichi Nonaka

Akinori Takehara

The present invention provides a rubber composition having adequate foamability, uses thereof, a copolymer contained in the rubber composition, a rubber composition capable of providing a cross-linked foam, which has a low specific gravity and an excellent shape-retaining property even when the usage of a nonconjugated polyene is reduced, and a cross-linked rubber and a cross-linked foam, which are produced from the rubber composition. A copolymer (A) according to the present invention is a copolymer including structural units derived from ethylene [A], an &#x3b1;-olefin [B], a nonconjugated polyene [C-1], in which one carbon-carbon double bond (C&#x2550;C) polymerizable with a metallocene catalyst is present in one molecule, and a nonconjugated polyene [C-2], in which two bonds of C&#x2550;C polymerizable with the metallocene catalyst are present in one molecule, and being synthesized with the metallocene catalyst, wherein (1) the units derived from the component [B] constitute 10 to 50 percent by mole, (2) the total of the units derived from the component [C-1] and the units derived from the component [C-2] is 1.0 to 6.0 percent by mole, (3) the molar ratio of the units derived from the component [C-1] to the units derived from the component [C-2] is 75/25 to 99.5/0.5, (4) [ML (1+4) 100&#xb0; C.] is 10 to 200, and (5) 50&#x3e;activation energy of fluidization (kJ/mol)&#x3e;35 is satisfied.

Copolymer, rubber composition, cross-linked rubber, cross-linked foam, and uses thereof

The invention provides a copolymer rubber excellent in processability in kneading and processability in extrusion; rubber compositions containing the rubber; and crosslinked moldings of the compositions excellent in sealing properties and shape retention. A random copolymer rubber of ethylene (A), a C&#x3b1;-olefin (B) and a nonconjugated polyene (C) which satisfies the following requirements (1) to (5): (1) the structural units (A) and (B) are contained at an (A)/(B) molar ratio of 40/60 to 95/5, (2) the structural unit (C) content is 0.01 to 5% by mole, (3) the limiting viscosity [&#x3b7;] is 1.0 to 5.0 dl/g as determined in decahydronaphthalene at 135&#xb0;., (4) the Mw/Mn is 1 to 8, and (5) the P value is 0.46 to 1.00 as defined by formula (1): P=Ln(limiting viscosity [&#x3b7;])&#x2212;5.0&#xd7;10&#xd7;&#x3b7;*(10) (1) (wherein Ln is a natural logarithm; and &#x3b7;*(10) is viscosity (Pa&#xb7;sec) as determined at 190&#xb0; C. and at 10 rad/sec.

Copolymer rubber, rubber composition and rubber molded product

Disclosed is a foam processable rubber composition which comprises an ethylene/.alpha.-olefin of 3 to 20 carbon atoms/non-conjugated polyene copolymer rubber (A), a crystalline polyolefin resin (B) having a melting point of 100 to 150.degree. C. and a foaming agent (C), in specific proportions. The copolymer rubber (A) has an ethylene/.alpha.-olefin molar ratio of 60/40 to 80/20, an intrinsic viscosity (.eta.), as measured in decalin at 135.degree. C., of 0.7 to 2 dl/g, and an iodine value of 10 to 50. A vulcanized rubber foam-molded product can be obtained by vulcanizing and foaming the rubber composition. The rubber composition can provide vulcanized rubber foam-molded products having excellent vulcanization properties such as weathering resistance, heat resistance, ozone resistance and tear strength. Besides, the rubber composition exhibits excellent precision moldability and productivity of vulcanized rubber foam-molded products in transfer molding, injection molding and cast molding.

Foam processable rubber compositions and vulcanized rubber foam molded

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Sodegaura, Japan

Masao Kunizane