Method for preparation of thermoplastic resin composition

Abstract

A two-step process for production of thermoplastic elastomer, which comprises dynamically vulcanizing polypropylene and olefinic rubber in the presence of peroxide (1st step), and dynamically vulcanizing the vulcanized mixture, polypropylene and halogenated butyl rubber in the presence of zinc oxide (2nd step). In another method (a) polyolefin and olefin rubber are dynamically cross-linked in the presence of an organic peroxide and (b) in a separate second operation a dynamically vulcanized blend comprising polyolefin and halogenated butyl rubber is prepared and mixed with (a) to disperse (a) and (b) in one another. The thermoplastic elastomer composition is useful in materials for parts of automobiles. In an example, pp 9 wt. % parts, EPDM 21 wt. % parts, peroxide 0.3 wt. % part and divinylbenzene 0.5 wt. % part were blended and supplied to the first hopper (1) of biaxial extruder as shown in a figure. In the first blending zone (2), temperature and residence time are 200.degree. C. and 60 seconds respectively. And then, to the second hopper (3) of the extruder, pp 50 parts and the vulcanized product (EPDM+chlorinated butyl rubber) 20 parts were supplied and extruded in the heat blending zone (4) above mentioned mixture for 30 seconds of residence time. The physical properties of the composition are MFR: 18, Flex. Mod.: 3,300 (23.degree. C.) and 1,150 (80.degree. C.), Tens. at break: 105, Elong.: 420%, Izod.: No break (room temperature) and 25 (-40.degree. C.) Shore-D: 58, Flow marks: good and paintability: 100/100.