PURPOSE: To efficiently produce a high-strength thermoplastic elastomer exhibiting an excellent elasticity even in the case of a low rubber content and excellent in heat resistance, etc., by dynamically heat treating a specified granular olefin polymer, a graft modifier and a free radical initiator.
CONSTITUTION: The objective graft-modified and cross-linked elastomer is obtained by dynamically heat-treating (A) a granular polymer composed of a crystalline olefin polymer part and an amorphous olefin polymer part, (B) a graft modifier (preferably maleic acid, etc.) and (C) a free radical initiator (preferably benzoyl peroxide, etc.). The dynamic heat treatment is recommendably carried out by melt-kneading the components (A) to (C) using an extruder in an atmosphere of an inert gas at 170 to 240°C for 1 to 10min. In addition, the component (A) is preferably obtained, e.g. by synthesizing the crystalline olefin part through a gas phase polymerization of a 2 to 8C α-olefin or/and another copolymerizable monomer and subsequently synthesizing the amorphous olefin polymer part through a gas phase polymerization.
OKAMOTO KATSUO
KIOKA MAMORU
UEDA TAKASHI
