PROCESS FOR PREPARING THERMOPLASTIC ELASTOMER COMPOSITIONS AND THERMOPLASTIC ELASTOMER COMPOSITIONS

PCT No. PCT/JP90/00885 Sec. 371 Date Dec. 13, 1990 Sec. 102(e) Date Dec. 13, 1990 PCT Filed Jul. 10, 1990 PCT Pub. No. WO91/00890 PCT Pub. Date Jan. 24, 1991.Thermoplastic elastomer compositions are prepared by feeding a mixture of (a) a peroxide crosslinking type olefin copolymer rubber, (b) a peroxide decomposition type olefin plastics and optionally, (c) a peroxide non-crosslinking type hydrocarbon rubbery substance through a hopper into a cylinder of an extrusion machine, and feeding simultaneously (d) a mineral oil type softener, or both (d) and (e) silicone oil, through an inlet provided on the cylinder separately from the hopper, thereby dynamically heat treating the resulting mixture in the presence of organic peroxide to prepare a partially crosslinked thermoplastic elastomer composition. Alternatively the mixture of the above-mentioned components (a) and (b), or (a), (b) and (c) are fed through a hopper into a cylinder of an extrusion machine so that the retention time of the mixture in the hopper is within 10 minutes, and feeding simultaneously (d) mineral oil type softener, or both (d) and (e) silicone oil into the hopper, thereby dynamically heat treating the resulting mixture in the presence of organic peroxide to prepare a partially crosslinked thermoplastic elastomer composition.