The present disclosure relates to a Ziegler-Natta catalyst system comprising a pro-catalyst, a co-catalyst and a selectivity control agent. The pro-catalyst comprises a magnesium compound, a titanium compound and a multi-dentate internal donor, wherein the internal donor is tetraethyl 3,3,3′,3′-tetramethyl-2,2′,3,3′-tetrahydro-1,1′-spirobiindane-5,5′,6,6′-tetracarbonate. The present disclosure further relates to a process for polymerization of an olefin using the Ziegler-Natta catalyst system. The Ziegler-Natta catalyst system of the present disclosure shows very high hydrogen response and thus can be used to produce low to high molecular weight polyolefin.

Catalyst system, the catalyst system comprising (i) at least one metallocene complex of formula (I) wherein Mt1 is Hf, X is a sigma-donor ligand, R.sup.1, R.sup.2, R.sup.3 are the same or different from each other and can be hydrogen or a saturated linear or branched C.sub.1-C.sub.10 alkyl, whereby the alkyl group can optionally contain up to 2 heteroatoms belonging to groups 14-16 of the periodic table, or R.sup.1 and R.sup.2 or R.sup.2 and R.sup.3 can form a ring having 4 to 6 C-atoms and 1 to 3 double bonds, R.sup.4 and R.sup.5 are the same or different from each other and can be saturated linear or branched C.sub.1-C.sub.10 alkyl, C.sub.5-C.sub.10 aryl, C.sub.6-C.sub.20 alkylaryl or C.sub.6-C.sub.20 arylalkyl groups, which can optionally contain up to 2 heteroatoms belonging to groups 14-16 of the periodic table, n can be 1 to 5, Ar is a C.sub.6-C.sub.20-aryl or -heteroaryl group, which can be unsubstituted or substituted by 1 to 5 linear or branched C.sub.1-C.sub.10 alkyl group(s), and (ii) an aluminoxane cocatalyst and (iii) optionally an aluminium alkyl compound AI(R.sup.7).sub.3, with R.sup.7 being a linear or branched C.sub.2-C.sub.8-alkyl group. ##STR00001##

The present disclosure relates to a method for preparing a polyolefin using a supported hybrid metallocene catalyst. According to the present disclosure, a polyolefin having a narrow molecular weight distribution can be prepared very effectively by introducing a cocatalyst in an optimum content in the presence of a supported hybrid metallocene catalyst containing two or more metallocene compounds having a specific chemical structure. The polyolefin prepared according to the present disclosure exhibits excellent uniformity in chlorine distribution in polyolefin during chlorination, thereby significantly improving elongation of the chlorinated polyolefin, compatibility with PVC and impact reinforcing performance. Thus, it exhibits excellent chemical resistance, weather resistance, flame retardancy, processability and impact strength reinforcing effect, and can be suitably applied as an impact reinforcing agent for PVC pipes and window profiles.

The present disclosure relates to a method for preparing a polyolefin using a supported hybrid metallocene catalyst. According to the present disclosure, a polyolefin having a narrow molecular weight distribution can be prepared very effectively by introducing a cocatalyst in an optimum content in the presence of a supported hybrid metallocene catalyst containing two or more metallocene compounds having a specific chemical structure. The polyolefin prepared according to the present disclosure exhibits excellent uniformity in chlorine distribution in polyolefin during chlorination, thereby significantly improving elongation of the chlorinated polyolefin, compatibility with PVC and impact reinforcing performance. Thus, it exhibits excellent chemical resistance, weather resistance, flame retardancy, processability and impact strength reinforcing effect, and can be suitably applied as an impact reinforcing agent for PVC pipes and window profiles.

The present invention relates to a process for producing a propylene polymer, such as a propylene homopolymer, a propylene-ethylene random copolymer or a heterophasic propylene copolymer using a specific class of metallocene complexes in combination with a cocatalyst system comprising a boron containing cocatalyst and an aluminoxane cocatalyst, preferably in a multistage polymerization process including a gas phase polymerization step.

Embodiments of the disclosure include processes of polymerizing olefins. The process includes contacting ethylene and a (C.sub.3-C.sub.40)alpha-olefin comonomer in the presences of a catalyst system. The catalyst system comprises a procatalyst and a bimetallic activator complex. The bimetallic activator complex comprises an anion and a countercation, and the anion has a structure according to formula (I).

Embodiments of the disclosure include processes of polymerizing olefins. The process includes contacting ethylene and a (C.sub.3-C.sub.40)alpha-olefin comonomer in the presences of a catalyst system. The catalyst system comprises a procatalyst and a bimetallic activator complex. The bimetallic activator complex comprises an anion and a countercation, and the anion has a structure according to formula (I).

A propylene copolymer, a preparation method therefor, and an application thereof are provided. The copolymer forms a cross-linked network by means of a reaction between a furan-containing propylene copolymer and a small molecule of a coupling agent, thereby achieving a chemical bond connection between a polypropylene resin phase and an ethylene-propylene copolymer elastomer phase, fundamentally strengthening the force between the two phases, and improving the mechanical properties of a material. Meanwhile, the copolymer can achieve the decrosslinking of a material during melt processing such that the material has thermoplasticity, and after cooling, it can be crosslinked again to produce network structure.

Disclosed is a catalyst for olefin polymerization, comprising a main catalyst and a cocatalyst; the main catalyst is a bisphenol metal complex represented by formula I, and the cocatalyst comprises an organoaluminum compound; in formula I, R.sub.1, R.sub.1′, R.sub.2, R.sub.2′ are the same or different, and are each independently selected from hydrogen and a substituted or unsubstituted C.sub.1-C.sub.20 hydrocarbyl; R.sub.3-R.sub.7, R.sub.3′-R.sub.7′ are the same or different, and are each independently selected from hydrogen and a substituted or unsubstituted C.sub.1-C.sub.20 hydrocarbyl; R.sub.8 and R.sub.9 are the same or different, and are each independently selected from hydrogen or a substituted or unsubstituted C.sub.1-C.sub.20 hydrocarbyl; M and M′ are the same or different, and are selected from Group IV metals; and X is halogen;

##STR00001##

This invention relates to polyolefin. More specifically, this invention relates to polyolefin that has small copolymer content, but exhibits excellent mechanical properties.