Propylene-ethylene copolymer composition and manufacture method

This invention relates to a propylene-ethylene copolymer formulation with excellent forming property and mechanic properties such as hardness, toughness, and impact resistance. The manufacture process includes a two-step solvent polymerization engineering (I and II). In polymerization I, a polypropylene whose melting flow ratio (ASTM D-1238) ranged within 100-1000g per 10 minutes is produced under the existence of high steric regularitied catalyst and hydrogen. The solvent (o-dichlorobenzene) temperature is increased continuously or stepwisely. At different temperatures, the solubility of propylene in o-dichlorobenzene is measured to indicate the inter-molecular steric regularity and molecular weight distribution. The resulted propylene copolymer should make up about 60-95 by the weight percentage of total copolymer whose ratio (Cf) of cumulative solubility in o-dicholorobenzene measured under 112 DEG C and above is less than 0.5. In polymerization II, the previous propylene polymer from polymerization I reacts with a propylene mixture with 30-80 by the weight percentage of ethylene. As the ethylene-propylene copolymer makes up to 5-40% of the total copolymer by weight, the propylene-ethylene copolymer composition with a melting flow ratio of 10-300 g/10ml can be obtained after adding alpha type or beta type crystalizing agent.