The present disclosure provides a supported hybrid catalyst which facilitates the preparation of polyolefins having improved bubble stability and exhibiting excellent processability for a blown film while maintaining high transparent haze and improved melt strength, and a method for preparing the same.

The present invention relates to a cascade process for the preparation of a graft copolymer comprising a polyolefin main chain and one or a multiple polymer side chains. The process comprising step A) of copolymerizing at least one first type of olefin monomer and at least one second type of metal-pacified functionalized olefin monomer using a catalyst system to obtain a polyolefin main chain having one or multiple metal-pacified functionalized short chain branches, the catalyst system comprising: i) a metal catalyst or metal catalyst precursor comprising a metal from Group 3-10 of the IUPAC Periodic Table of elements; and ii) optionally a co-catalyst; and step B) of forming one or multiple polymer side chains on the polyolefin main chain having one or multiple metal-pacified functionalized short chain branches to obtain the graft copolymer.

The polypropylene nonwoven fabric produced by the method for producing a polypropylene nonwoven fabric according to the present invention has features that it has excellent stretchability and excellent water pressure resistance.

The present disclosure relates to a polyethylene suitable for preparing fibers with enhanced yellow index and filterability in the spinning process by having improved aging lifetime of the polyethylene, and a preparation method of the same.

Catalyst systems and methods for making and using the same. A method of methylating a catalyst composition while substantially normalizing the entiomeric distribution is provided. The method includes slurrying the organometallic compound in dimethoxyethane (DME), and adding a solution of RMgBr in DME, wherein R is a methyl group or a benzyl group, and wherein the RMgBr is greater than about 2.3 equivalents relative to the organometallic compound. After the addition of the RMgBr, the slurry is mixed for at least about four hours. An alkylated organometallic is isolated, wherein the methylated species has a meso/rac ratio that is between about 0.9 and about 1.2.

Ethylene-based polymers having a density of 0.952 to 0.968 g/cm.sup.3, a ratio of HLMI/MI from 185 to 550, an IB parameter from 1.46 to 1.80, a tan at 0.1 sec.sup.1 from 1.05 to 1.75 degrees, and a slope of a plot of viscosity versus shear rate at 100 sec.sup.1 from 0.18 to 0.28 are described, with low melt flow versions having a HLMI from 10 to 30 g/10 min and a Mw from 250,000 to 450,000 g/mol, and high melt flow versions having a HLMI from 30 to 55 g/10 min and a Mw from 200,000 to 300,000 g/mol. These polymers have the processability of chromium-based resins, but with improved stress crack resistance and topload strength for bottles and other blow molded products.

Catalyst systems and methods for making and using the same. A method of methylating a catalyst composition while substantially normalizing the entiomeric distribution is provided. The method includes slurrying the organometallic compound in dimethoxyethane (DME), and adding a solution of RMgBr in DME, wherein R is a methyl group or a benzyl group, and wherein the RMgBr is greater than about 2.3 equivalents relative to the organometallic compound. After the addition of the RMgBr, the slurry is mixed for at least about four hours. An alkylated organometallic is isolated, wherein the methylated species has a meso/rac ratio that is between about 0.9 and about 1.2.

The present disclosure relates to dual catalyst systems and processes for use thereof. The present disclosure further provides a catalyst system that is a combination of at least two hafnium metallocene catalyst compounds. The catalyst systems may be used for olefin polymerization processes. The present disclosure further provides for polymers, which can be formed by processes and catalyst systems of the present disclosure.

This invention relates to hafnium metallocene compounds having a group substituted (preferably at the 3 position) on at least one cyclopentadienyl ring represented by the formula R.sup.20SiR.sub.3 or R.sup.20CR.sub.3 where R.sup.20 is a C.sub.1 to C.sub.4 hydrocarbyl (preferably methyl) and R is a C.sub.1 to C.sub.20 substituted or unsubstituted hydrocarbyl.

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 includes at least one of the following general formulas:

##STR00001##

In both catalyst systems, the R groups can be independently selected from any number of substituents, including, for example, H, a hydrocarbyl group, a substituted hydrocarbyl group, or a heteroatom group, among others.