FIELD: polymers.
SUBSTANCE: invention relates to a composition of a procatalyst for the stereoselective polymerization of propylene, a catalytic system and a polymerization method. The composition of the procatalyst contains: a combination of a magnesium fragment, a titanium fragment, and a mixed internal electron donor, with the mixed internal electron donor containing at least the first internal electron donor and the second internal electron donor. The first internal electron donor contains a non-phthalate and non-succinate internal electron donor, wherein this first internal electron donor has the following structure:
,
in which substituents R1-R4 are the same or different, and each of substituents R1-R4 is selected from a group including a hydrogen atom, a substituted hydrocarbyl group having from 1 to 20 carbon atoms, an unsubstituted hydrocarbyl group having from 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having from 6 to 20 carbon atoms, an alkoxy group having from 1 to 20 carbon atoms, a heteroatom and a combination thereof, and at least, one of substituents R1-R4 is not a hydrogen atom; and at least one, or two, or three, or four R groups from R1-R4 are selected from a substituted hydrocarbyl group having 1 to 20 carbon atoms, an unsubstituted hydrocarbyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a heteroatom and their combinations, and wherein substituents E1 and E2 are the same or different and contain an aryl having 6 to 20 carbon atoms, or a substituted aryl having 6 to 20 carbon atoms. The second internal electron donor contains a 1,3-diester. The catalytic system contains a procatalyst composition and a cocatalyst. The polymerization method includes: polymerizing an olefin in the presence of a catalyst composition containing a Ziegler-Natta procatalyst composition, a cocatalyst composition and optionally an external electron donor compound, wherein the procatalyst composition is formed from a transition metal compound and a mixture of internal electron donors containing at least the above first internal electron donor and second internal electron donor.
EFFECT: composition exhibits excellent polymerization activity and hydrogen response, and can produce a polyolefin exhibiting high stereoregularity, high melt flow index, low xylene soluble content, and desired molecular weight distribution.
26 cl, 2 tbl, 5 ex
