POLYOLEFIN COMPOSITION AND A METHOD OF ITS PREPARING Russian patent published in 1995 - IPC

FIELD: chemical technology. SUBSTANCE: composition has, %: propylene copolymer with 3.0-4.3 wt.-% ethylene 28.2-43.0; xylene insoluble copolymer fraction of ethylene with propylene 9.37-11.34 and xylene soluble copolymer fraction of ethylene with propylene 46.6-60.55. Source of latter is copolymer of 27.0-34.8 wt. -% ethylene with propylene showing specific viscosity 1.86-2.18 dl/l. Composition is prepared by two-step copolymerization using catalyst consisting of trialkylaluminium, electrodonor and solid component which are applied on the anhydrous magnesium chloride activated with alcohol, titanium halogenide and dicarboxylic acid ester with specific surface 66,5 m²/g, porosity is 0,261 cm³/g and volume mass is 0,55 g/cm³. At the first stage propylene is copolymerized with ethylene for 20-30 min in the presence of gaseous phase - 0.1-0.58 mol.% hydrogen and 1.45-2.60 mol.% ethylene, and copolymer of propylene with 3.0-4.3 wt.-% ethylene is prepared. Unreacted monomers were removed, and copolymerization of ethylene with propylene is carried out at the second stage for 250-500 min; content of hydrogen and ethylene in the gaseous phase is 2.1-3.0 and 15.9-22.54 mol.%, respectively. Xylene soluble and insoluble fractions were obtained at the second stage at the ratio 4.5-7.1. Composition is used in medicinal equipment. EFFECT: improved method of composition preparing. 3 cl, 2 tbl