# US 5,346,987 A · Preparation of compounded rubber composition from bubble-containing ethylene/.alpha.-olefin rubber

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- Number: US 5,346,987 A
- Document ID: US5346987A
- Status: Granted
- Kind: A
- Application number: 07/947,972
- Filed: 1992-09-21
- Granted: 1994-09-13
- Earliest claimed: 1988-10-14
- Assignees: Mitsui Petrochemical Industries, Ltd.
- Inventors: Takashi Nakahara; Toshiaki Kimura; Takashi Mishima
- Web page: https://patentgrep.com/patent/US5346987A

## CPC

- C08J 9/122: {Hydrogen, oxygen, CO2, nitrogen or noble gases}
- C08J 9/12: by a physical blowing agent
- C08J 2323/16: Ethene-propene or ethene-propene-diene copolymers
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)

## Abstract

In accordance with the present invention, there is provided a bubble-containing ethylene/.alpha.-olefin rubber excellent in kneadability, characterized in that the ethylene/.alpha.-olefin rubber prepared by copolymerization of 50-95 mol % of ethylene, 5-50 mol % of .alpha.-olefin having at least 3 carbon atoms and 0-10 mol % of non-conjugated polyene contains 5-1000 parts by volume, based on 100 parts by volume of said rubber, of bubbles and has a water absorption volume as measured in accordance with ASTM D 1506 of less than 20% by volume of the total bubble volume.

## Claims

### Claim 1

A process for preparing a compounded, bubble-free rubber composition which comprises mixing and kneading at least one compounding agent selected from reinforcing materials, fillers, softeners and vulcanizing accelerators with a base rubber comprising (A) a non-vulcanized copolymer of (1) about 50 to 95 mol % of ethylene, (2) about 5 to 50 mol % of .alpha.-olefin having at least 3 carbon atoms, and (3) 0 to about 10 mol % of non-conjugated polyene and (B) 5-1000 parts by volume, based on 100 parts by volume of the base rubber, of bubbles and providing a water absorption volume as measured in accordance with ASTM D1506 of less than 20% by volume of the total volume of bubbles.

### Claim 2

A process for preparing a compounded rubber composition, which comprises (I) preparing a non-vulcanized bubble-containing ethylene/.alpha.-olefin copolymer rubber by the steps of
(A) heating an ethylene/.alpha.-olefin copolymer rubber obtained by polymerizing:
(1) 50-90 mol % of ethylene,
(2) 5-50 mol % of .alpha.-olefin having at least 3 carbon atoms; and
(3) 0-10 mol % of non-conjugated polyene, to at least the softening temperature of the rubber,
(B) kneading the softened rubber while blowing a gaseous substance thereinto; and
(C) extruding the gaseous substance-containing rubber, followed by cooling; wherein said rubber contains from 5 to 1000 parts by volume, based on 100 parts by volume of said ethylene/.alpha.olefin copolymer rubber of step (A), of bubbles and providing a water absorption volume as measured in accordance with ASTM D 1506 of less than 20% by volume of the total volume of bubbles, and (II) kneading the resulting ethylene/.alpha.-olefin copolymer rubber with a compounding agent selected from reinforcing materials, fillers, softeners, vulcanizing accelerators and vulcanizers, said bubbles being dissipated in said compound rubber.