OLEFIN THERMOPLASTIC ELASTOMER COMPOSITIONS

摘要

An olefin thermoplastic elastomer compositions of the invention is in a non-crosslinked or crosslinked form and comprises a crystalline polyolefin resin (A) and an ethylene/.alpha.-olefin/nonconjugated polyene copolymer rubber (B), and optionally a softer (C) and/or an inorganic filler (D), in a specific ratio. The copolymer rubber (B) is prepared by the use of a metallocene catalyst and comprises ethylene, an .alpha.-olefin of 3 to 20 carbon atoms and a nonconjugated polyene. This composition can provide molded products of more excellent tensile strength, elongation at break, elastomeric properties (elongation set, permanent compression set, etc.), heat resistance and low-temperature properties than the conventional non-crosslinked olefin thermoplastic elastomers, even if the composition is in the non-crosslinked form. The composition in the partially or completely crosslinked form can provide molded products of more excellent low-temperature properties, tensile strength, elongation at break and elastomeric properties than the conventional vulcanized rubbers. The other olefin thermoplastic elastomer compositions comprises a crystalline polyolefin resin (E) and an ethylene/.alpha.-olefin copolymer rubber (F), and optionally an olefin rubber (G) and/or a softener (H), in a specific ratio, and is partially or completely crosslinked. The copolymer rubber (F) is obtained by random copolymerizing ethylene and an .alpha.-olefin of 3 to 20 carbon atoms in the presence of a metallocene catalyst and has (1) a specific molar ratio ((a)/(b)) of units derived from ethylene (a) to units derived from the .alpha.-olefin of 3 to 20 carbon atoms (b), (2) a specific density, (3) a specific melt flow rate and (4) a specific intrinsic viscosity (?). This thermoplastic elastomer composition can provide molded products of more excellent tensile properties such as tensile strength and elongation at break than the conventional vulcanized rubbers.