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.

Processes of polymerizing olefin monomers using catalyst systems and catalysts systems that include a procatalyst having a structure according to formula (I):

Processes of polymerizing olefin monomers using catalyst systems and catalysts systems that include a procatalyst having a structure according to formula (I):

A polyethylene suitable for use in blown film can comprise ethylene derived units and C.sub.3 to C.sub.12 α-olefin derived units at 0.5 wt % to 10 wt % of the polyethylene and have a reversed-co-monomer index (RCI,m) of 35 to 100, a comonomer distribution ratio (CDR-2,m) of 1.20 to 1.80, and a weight average molecular weight (Mw) to number average molecular weight (Mn) of 5 to 7.

A polyethylene suitable for use in blown film can comprise ethylene derived units and C.sub.3 to C.sub.12 α-olefin derived units at 0.5 wt % to 10 wt % of the polyethylene and have a reversed-co-monomer index (RCI,m) of 35 to 100, a comonomer distribution ratio (CDR-2,m) of 1.20 to 1.80, and a weight average molecular weight (Mw) to number average molecular weight (Mn) of 5 to 7.

A polyethylene comprising of ethylene derived units and 0.5 wt % to 10 wt % C.sub.3 to C.sub.12 α-olefin derived units may be synthesized using a mixed catalyst that comprises rac-dimethylsilylbis(tetrahydroindenyl)zirconium dichloride and a zirconium co-catalyst in a mole ratio of 50:50 to 90:10, and wherein the zirconium co-catalyst is a poor comonomer incorporator as compared to the rac-dimethylsilylbis(tetrahydroindenyl)zirconium dichloride catalyst. Such a polyethylene may have a density of 0.91 g/cm.sup.3 to 0.93 g/cm.sup.3, an I.sub.2 value of 0.5 g/10 min to 2 g/10 min, an I.sub.21 value of 25 g/10 min to 75 g/10 min, an I.sub.21/I.sub.2 ratio of 25 to 75, a molar reversed-co-monomer index (RCI,m) of 30 to 180, a phase angle equal or lower than 70° at complex modulus G* of 10,000 Pa, a Θ.sub.2 of 1.5 radians to −1.5 radians, and a low density population of 50% and 70% by weight of the polyethylene.

A polyethylene comprising of ethylene derived units and 0.5 wt % to 10 wt % C.sub.3 to C.sub.12 α-olefin derived units may be synthesized using a mixed catalyst that comprises rac-dimethylsilylbis(tetrahydroindenyl)zirconium dichloride and a zirconium co-catalyst in a mole ratio of 50:50 to 90:10, and wherein the zirconium co-catalyst is a poor comonomer incorporator as compared to the rac-dimethylsilylbis(tetrahydroindenyl)zirconium dichloride catalyst. Such a polyethylene may have a density of 0.91 g/cm.sup.3 to 0.93 g/cm.sup.3, an I.sub.2 value of 0.5 g/10 min to 2 g/10 min, an I.sub.21 value of 25 g/10 min to 75 g/10 min, an I.sub.21/I.sub.2 ratio of 25 to 75, a molar reversed-co-monomer index (RCI,m) of 30 to 180, a phase angle equal or lower than 70° at complex modulus G* of 10,000 Pa, a Θ.sub.2 of 1.5 radians to −1.5 radians, and a low density population of 50% and 70% by weight of the polyethylene.

A biaxially-oriented film comprising a polyethylene having (A) a melt flow index of 1.0 g/10 min or more, (B) a density of 0.90 g/cm3 to less than 0.940 g/cm.sup.3, (C) a g′.sub.LCB of greater than 0.8, (D) ratio of comonomer content at Mz to comonomer content at Mw is greater than 1.0, (E) ratio of comonomer content at Mn to comonomer content at Mw is greater than 1.0, and (F) a ratio of the g′.sub.LCB to the g′.sub.zave is greater than 1.0, and where the film has a 1% secant in the transverse direction of 70,000 psi or more and Dart Drop of 350 g/mil or more.

A biaxially-oriented film comprising a polyethylene having (A) a melt flow index of 1.0 g/10 min or more, (B) a density of 0.90 g/cm3 to less than 0.940 g/cm.sup.3, (C) a g′.sub.LCB of greater than 0.8, (D) ratio of comonomer content at Mz to comonomer content at Mw is greater than 1.0, (E) ratio of comonomer content at Mn to comonomer content at Mw is greater than 1.0, and (F) a ratio of the g′.sub.LCB to the g′.sub.zave is greater than 1.0, and where the film has a 1% secant in the transverse direction of 70,000 psi or more and Dart Drop of 350 g/mil or more.

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##