Patent ID: 6365685
Filing Date: 2002-04-02
Classification: C08F

Abstract:
A process for the preparation of random propylene copolymers which contain up to 15% by weight of ethylene, in which the natural logarithm of the content by weight of xylene-soluble fraction and the weight percentage of ethylenic units define points below the straight line given by the equation:ln(Xs)=ln(a)+bC2 whereinXs=% by weight of the fraction soluble in xylene at 25Â° C.; C2=% by weight of ethylenic units in the copolymer; a=from 1.55 to 1.73; b=0.29; the process comprising contacting ethylene and propylene in the presence of a catalyst comprising:(A) a solid component comprising a titanium compound supported on a magnesium chloride in active form and an electron-donor compound; (B) an alkyl-Al compound; and (C) an electron donor-compound selected from the group of 1,3-diethers of formula (I): â€ƒwherein R, RI, RII, RIII, RIV, and, RV, which are identical or different, are hydrogen or linear or branched alkyl radicals, cycloalkyl radicals, aryl radicals, alkylaryl radicals or arylalkyl radicals having 1-18 carbon atoms; with the limitation that R and RI cannot simultaneously be hydrogen and that at least one of R and RI is a secondary or tertiary hydrocarbon radical selected from alkyl, cycloalkyl, or aromatic groups; wherein RVI and RVII, which are identical or different, are linear or branched alkyl radicals, cycloalkyl radicals, aryl radicals, alkylaryl radicals or arylalkyl radicals having 1-18 carbon atoms; and further wherein at least two of the radicals R,RI, RII, RIII, RIV, RV, RVI, and RVII can be linked together to form one or more cyclic structures.