ETHYLENE/PENTENE-1 COPOLYMER FOR INJECTION MOLDING AND INJECTION-MOLDED MATERIAL OF SAID COPOLYMER

摘要

PURPOSE:To obtain the subject new copolymer particularly suitable for producing an injection-molded material having excellent environmental stress cracking resistance and transparency 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 2.0-50g/10min measured by ASTM-D-1238E, a density (d) in the range of 0.900-0.945g/cm<3> measured by ASTM-D-1505 and a content of repeating unit derived from pentene-1 in the range of 2-20wt.%. A pressed board having 2mm thickness molded from the copolymer by applying ASTM- D-1928 method exhibits >=10hr environmental stress-cracking resistance (ESCR) measured by ASTM-D-1692 and <=20% haze (Haze) measured by ASTM-D-1003 and the above-mentioned values satisfy formula I and formula II.