A solid catalyst component for the polymerization of olefins made from or containing Mg, Ti, halogen and an electron donor of formula (I) or (II) ##STR00001## When activated with an aluminum alkyl and optionally an external electron donor, solid catalyst component can give high activity and stereospecificity in the polymerization of olefins.

The present disclosure relates to a catalyst component for the polymerization of olefins comprising Mg. Ti and an electron donor such as mercaptoester derivatives of the general formula (I). ##STR00001##
in which Z is selected from C, Si, O, N, S or P, with the proviso that the atoms O, S, P and N are not directly linked to either the carboxylic group or the sulfur atom of formula (I), the R.sup.2 groups, equal to or different from each other, are selected from hydrogen or a C.sub.1-C.sub.20 hydrocarbon radicals, optionally containing a heteroatom selected from halogen, P, S, N, O and Si, which can be fused together to form one or more cycles, m is a number satisfying the valences of Z and n is an integer ranging from 1 to 10, X is O or S, Y is OR.sup.3, NR.sup.4R.sup.5) or R.sup.6 groups in which R.sup.1 and R.sup.3 are selected from C.sub.1-C.sub.15 hydrocarbon groups, optionally containing a heteroatom selected from halogen, P, S, N, O, and Si, R.sup.4-R.sup.5 groups, independently, are hydrogen or R.sup.1 groups, and R.sup.6 groups have the same composition as R.sup.1 groups.

A solid catalyst component for the polymerization of olefins made from or containing Mg, Ti, halogen and an electron donor of formula (I) or (II)

##STR00001##

When activated with an aluminum alkyl and optionally an external electron donor, solid catalyst component can give high activity and stereospecificity in the polymerization of olefins.

The present disclosure relates to a catalyst component for the polymerization of olefins comprising Mg. Ti and an electron donor such as mercaptoester derivatives of the general formula (I).

##STR00001##

in which Z is selected from C, Si, O, N, S or P, with the proviso that the atoms O, S, P and N are not directly linked to either the carboxylic group or the sulfur atom of formula (I), the R.sup.2 groups, equal to or different from each other, are selected from hydrogen or a C.sub.1-C.sub.20 hydrocarbon radicals, optionally containing a heteroatom selected from halogen, P, S, N, O and Si, which can be fused together to form one or more cycles, m is a number satisfying the valences of Z and n is an integer ranging from 1 to 10, X is O or S, Y is OR.sup.3, NR.sup.4R.sup.5) or R.sup.6 groups in which R.sup.1 and R.sup.3 are selected from C.sub.1-C.sub.15 hydrocarbon groups, optionally containing a heteroatom selected from halogen, P, S, N, O, and Si, R.sup.4-R.sup.5 groups, independently, are hydrogen or R.sup.1 groups, and R.sup.6 groups have the same composition as R.sup.1 groups.

The present disclosure provides a heterogeneous Ziegler-Natta catalyst system to be used in the preparation of ultra-high molecular weight polymers (UHMWP). The system includes at least one procatalyst, at least one co-catalyst, at least one hydrocarbon medium and at least one external donor, wherein the ratio of elemental magnesium to elemental titanium to halide, in the procatalyst, is 1:1.3:3.7; the ratio of elemental aluminum, present in the co-catalyst to elemental titanium, present in the procatalyst, ranges between 6:1 and 12:1; and the ratio of elemental silicon, present in the external donor to elemental titanium, present in the procatalyst, ranges between 1:10 and 10:1. The present disclosure also provides a process for preparation of UHMWPE using the heterogeneous Ziegler-Natta catalyst system of the present disclosure.

Catalyst systems containing a Ziegler-Natta catalyst component are disclosed. Such catalyst systems can contain a co-catalyst and a supported catalyst containing a fluorided silica-coated alumina, a magnesium compound, and vanadium and/or tetravalent titanium.

Catalyst systems containing a Ziegler-Natta catalyst component are disclosed. Such catalyst systems can contain a co-catalyst and a supported catalyst containing a fluorided silica-coated alumina, a magnesium compound, and vanadium and/or tetravalent titanium.