ETHYLENE/PENTENE-1 COPOLYMER FOR ROTATIONAL MOLDING AND ROTATIONALLY MOLDED MATERIAL

摘要

PURPOSE:To obtain the subject copolymer suitable for producing a rotationally molded material in a short molding cycle having excellent environmental stress cracking resistance and impact resistance having a specific melt flow rate, density and ethylene/pentene-1 content expressed in terms of monomer weight. CONSTITUTION:Ethylene and pentene-1 are copolymerized in the presence of a catalyst comprising a component of MgCl2 carrying Ti-tetraethoxide and an organic Al compound to afford the aimed copolymer having a melt flow rate (MFR) in the range of 1.0-20g/10min a density (d) in the range of 0.900-0.945g/cm3 and a content of repeating unit derived from pentene-1 in the range of 2-20wt.%. A pressed board having 2mm thickness using the copolymer exhibits =20hr environmental stress-cracking resistance (ESCR) and molding cycle (MS) for molding a cylindrical bottle having 20l volume using powder of the copolymer comprising =4wt.% not passing through 32 mesh sieves, =3wt.% passing through 200 mesh sieves and =80wt.% from passing through 32 mesh sieves to not passing of 80 mesh sieves is =15min/piece, and the above- mentioned values satisfy formula I and formula II.