PROPYLENE-ETHYLENE COPOLYMER COMPOSITIONS AND PROCESS FOR THE PRODUCTION THEREOF

摘要

A propylene-ethylene copolymer composition is obtained which has a good moldability and is excellent in the balance of rigidity, toughness, and impact-strength. A propylene-ethylene copolymer composition having a melt flow rate of 10 to 300 g/10 minutes and obtained by producing 60 to 95 % by weight, based on the weight of whole polymer, of a propylene polymer having a melt flow rate (ASTM D-1238) in the range of 100 to 1,000 g/10 minutes and having a ratio (Cf) of integrated values of the propylene polymer dissolved in o-dichlorobenzene at a temperature of lower than 112 DEG C, and a temperature of 112 DEG C or higher, respectively, which is an index of the stereoregurality in molecules and molecular weight distribution, when the amounts of the propylene polymer dissolved therein at each of the temperatures were determined by raising the temperature of the o-dichlorobenzene continuously or stepwise, of 0.5 or less, by carrying out polymerization of propylene in the presence of a highly stereoregular catalyst and hydrogen in a polymerization step (I), and then producing 5 to 40 % by weight, based on the weight of whole polymer, of an ethylene-propylene copolymer by feeding ethylene and propylene to the propylene polymer produced in the polymerization step (I) to react so that the content of ethylene becomes 30 to 80 % by weight, in a polymerization step (II); and a propylene-ethylene copolymer composition comprising the composition mentioned above and a alpha -crystal and/or beta -crystal nucleator added therewith.