A Ziegler-Natta catalyzed ethylene/alpha-olefins copolymer is provided having sporadic long chain branches and reversed comonomer composition distribution or short chain branching distribution (SCBD) in the high molecular weight fractions. According to the invention, polyethylene film made with the inventive copolymer has a balance of improved physical, optical, mechanical properties as well as processability. In one aspect, the film includes a 1% secant modulus of greater than 25,000 psi, a film haze of less than 10, a film clarity of greater than 90, a dart impart resistance of greater than 500 g/mil, and a MD tear strength of greater than 500 g/mil.

A Ziegler-Natta catalyzed ethylene/alpha-olefins copolymer is provided having sporadic long chain branches and reversed comonomer composition distribution or short chain branching distribution (SCBD) in the high molecular weight fractions. According to the invention, polyethylene film made with the inventive copolymer has a balance of improved physical, optical, mechanical properties as well as processability. In one aspect, the film includes a 1% secant modulus of greater than 25,000 psi, a film haze of less than 10, a film clarity of greater than 90, a dart impart resistance of greater than 500 g/mil, and a MD tear strength of greater than 500 g/mil.

A catalyst composition for polymerizing a polyolefin having excellent processability and impact strength, a process for producing a polyolefin and a polyolefin resin thereof are disclosed. The catalyst composition comprises at least one first organometallic compound of following formula 1; at least one second organometallic compound of following formula 2; and aluminoxane. The polyolefin resin satisfies following properties (i) to (iv) and (vi), (i) melt flow index (ASTM D1238), measured at 190° C., under a load of 2.16 kg: 0.1 to 1.5 g/10 min, (ii) density: 910 to 930 kg/m.sup.3, (iii) the ratio (Mw/Mn), as measured by gel permeation chromatography (GPC): 3.0 to 7.0, (iv) the ratio (Mz/Mw), as measured by GPC: 2.2 to 4.5, and (vi) when the TREF curve of multimodal distribution is deconvoluted, the area of TREF curve having a peak at 50 to 74° C. is 40 to 75% of the total area of the TREF curve.

A catalyst composition for polymerizing a polyolefin having excellent processability and impact strength, a process for producing a polyolefin and a polyolefin resin thereof are disclosed. The catalyst composition comprises at least one first organometallic compound of following formula 1; at least one second organometallic compound of following formula 2; and aluminoxane. The polyolefin resin satisfies following properties (i) to (iv) and (vi), (i) melt flow index (ASTM D1238), measured at 190° C., under a load of 2.16 kg: 0.1 to 1.5 g/10 min, (ii) density: 910 to 930 kg/m.sup.3, (iii) the ratio (Mw/Mn), as measured by gel permeation chromatography (GPC): 3.0 to 7.0, (iv) the ratio (Mz/Mw), as measured by GPC: 2.2 to 4.5, and (vi) when the TREF curve of multimodal distribution is deconvoluted, the area of TREF curve having a peak at 50 to 74° C. is 40 to 75% of the total area of the TREF curve.

A propylene resin composition includes a propylene polymer (A) satisfying requirements (1) to (3) below: (1) having a number average molecular weight (Mn) measured by gel permeation chromatography (GPC) of 5000 to 22000; (2) having a ratio (Mw/Mn) of a weight average molecular weight (Mw) to a number average molecular weight (Mn) measured by gel permeation chromatography (GPC) being 1.2 to 3.5; and (3) having a proportion of a component eluted at a temperature of not more than −20° C. in temperature rising elution fractionation (TREF) being not more than 3.5 mass %.

A propylene resin composition includes a propylene polymer (A) satisfying requirements (1) to (3) below: (1) having a number average molecular weight (Mn) measured by gel permeation chromatography (GPC) of 5000 to 22000; (2) having a ratio (Mw/Mn) of a weight average molecular weight (Mw) to a number average molecular weight (Mn) measured by gel permeation chromatography (GPC) being 1.2 to 3.5; and (3) having a proportion of a component eluted at a temperature of not more than −20° C. in temperature rising elution fractionation (TREF) being not more than 3.5 mass %.

Catalyst systems and methods for making and using the same. A method of polymerizing olefins to produce a polyolefin polymer with a multimodal composition distribution, includes contacting ethylene and a comonomer with a catalyst system. The catalyst system includes a first catalyst compound and a second catalyst compound that are co-supported to form a commonly supported catalyst system. The first catalyst compound includes a compound with the general formula (C.sub.5H.sub.aR.sup.1.sub.b)(C.sub.5H.sub.cR.sup.2.sub.d)HfX.sub.2. The second catalyst compound comprises the following formula:

##STR00001##

wherein each R.sup.3 or R.sup.4 is independently H, a hydrocarbyl group, a substituted hydrocarbyl group, or a heteroatom group, wherein each R.sup.3 or R.sup.4 may be the same or different, and each X is independently a leaving group selected from a labile hydrocarbyl, a substituted hydrocarbyl, a heteroatom group, or a divalent radical that links to an R.sup.3 group.

Catalyst systems and methods for making and using the same. A method of polymerizing olefins to produce a polyolefin polymer with a multimodal composition distribution, includes contacting ethylene and a comonomer with a catalyst system. The catalyst system includes a first catalyst compound and a second catalyst compound that are co-supported to form a commonly supported catalyst system. The first catalyst compound includes a compound with the general formula (C.sub.5H.sub.aR.sup.1.sub.b)(C.sub.5H.sub.cR.sup.2.sub.d)HfX.sub.2. The second catalyst compound comprises the following formula:

##STR00001##

wherein each R.sup.3 or R.sup.4 is independently H, a hydrocarbyl group, a substituted hydrocarbyl group, or a heteroatom group, wherein each R.sup.3 or R.sup.4 may be the same or different, and each X is independently a leaving group selected from a labile hydrocarbyl, a substituted hydrocarbyl, a heteroatom group, or a divalent radical that links to an R.sup.3 group.

In the present disclosure, there are provided a polyethylene having improved low-temperature sealing properties with an increase in the content and molecular weight of a low crystalline polymer, and a method for preparing the same.

In the present disclosure, there are provided a polyethylene having improved low-temperature sealing properties with an increase in the content and molecular weight of a low crystalline polymer, and a method for preparing the same.