The present invention is concerned with a process for polymerizing ethylene or copolymerizing ethylene and at least one alpha-olefin comonomer in the presence of a supported polymerization catalyst in a multi-stage process in which the last polymerization stage is a gas phase reactor, the use of said process for reducing particle carry-over in the last polymerization stage and the use of a supported polymerization catalyst with a certain median particle size to polymerize an ethylene homo- or copolymer in said multi-stage process with a span of its particle size distribution which can be predicted from the median particle size of the catalyst.

This disclosure relates to a continuous solution polymerization process where ethylene interpolymer products having an improved color index; for example, products having higher whiteness (Whiteness Index (WI)) and lower yellowness (Yellowness Index (YI)). Product color was improved by adjusting selected solution polymerization reaction conditions. The disclosed ethylene interpolymer products have improved color relative to comparative polyethylene compositions.

Methods of making spray-dried Ziegler-Natta (pro)catalyst systems containing titanium Ziegler-Natta (pro)catalysts, a hydrophobic silica carrier material, and tetrahydrofuran. The spray-dried Ziegler-Natta (pro)catalyst systems made by the method. Methods of polymerizing olefin (co)monomer(s) with the spray-dried Ziegler-Natta catalyst system to make polyolefin polymers, and the polyolefin polymers made thereby.

A heterogeneous procatalyst includes a preformed heterogeneous procatalyst and a metal-ligand complex. The preformed heterogeneous procatalyst includes a titanium species and a magnesium chloride (MgCl.sub.2) support. The metal-ligand complex has a structural formula (L).sub.aM(Y).sub.m(XR.sup.2).sub.b, where M is a metal cation; each L is a neutral ligand or (═O); each Y is a halide or (C.sub.1-C.sub.20)alkyl; each XR.sup.2 is an anionic ligand in which X is a heteroatom or a heteroatom-containing functional group and R.sup.2 is (C.sub.1-C.sub.20)hydrocarbyl or (C.sub.1-C.sub.20) heterohydrocarbyl; n is 0, 1, or 2; m is 0-4; and b is 1-6. The metal-ligand complex is overall charge neutral. The heterogeneous procatalyst exhibits improved average molecular weight capability. A catalyst system includes the heterogeneous procatalyst and a cocatalyst. Processes for producing the heterogeneous procatalyst and processes for producing ethylene-based polymers utilizing the heterogeneous procatalyst are also disclosed.

The present disclosure provides a method for improving the activity of Ziegler-Natta (ZN) catalysts. The method includes forming a modified precursor composition of a ZN catalyst by providing a precursor composition of the ZN catalyst for treatment with an aluminum alkyl compound in a liquid organic solvent. The precursor composition of the ZN catalyst includes at least one titanium compound. The at least one titanium compound in the precursor composition is treated with the aluminum alkyl compound in the liquid organic solvent, where the aluminum alkyl compound converts the at least one titanium compound in the precursor composition into a modified state of the ZN catalyst. At least a portion of the aluminum alkyl compound not consumed in converting the at least one titanium compound in the precursor composition into the modified state of the ZN catalyst and reaction by-product compounds in the liquid organic solvent are removed to form the modified precursor composition of the ZN catalyst.

The present disclosure provides a method for improving the activity of Ziegler-Natta (ZN) catalysts. The method includes forming a modified precursor composition of a ZN catalyst by providing a precursor composition of the ZN catalyst for treatment with an aluminum alkyl compound in a liquid organic solvent. The precursor composition of the ZN catalyst includes at least one titanium compound. The at least one titanium compound in the precursor composition is treated with the aluminum alkyl compound in the liquid organic solvent, where the aluminum alkyl compound converts the at least one titanium compound in the precursor composition into a modified state of the ZN catalyst. At least a portion of the aluminum alkyl compound not consumed in converting the at least one titanium compound in the precursor composition into the modified state of the ZN catalyst and reaction by-product compounds in the liquid organic solvent are removed to form the modified precursor composition of the ZN catalyst.

A multilayer blown film having an inner layer, a first outer layer, and a second outer layer, wherein the inner layer comprises an ethylene-based polymer having a MWCDI value greater than 0.9, and a melt index ratio (I10/I2) that meets the following equation: I10/I2≥7.0−1.2×log (I2); and the first outer layer and the second outer layer independently comprise a polyethylene composition which comprises the reaction product of ethylene and, optionally, one or more alpha olefin comonomers, wherein the polyethylene composition is characterized by the following properties: (a) a melt index, I.sub.2, of from 0.1 to 2.0 g/10 min; (b) a density of from 0.910 to 0.930 g/cc; (c) a melt flow ratio, I.sub.10/I.sub.2, of from 6.0 to 7.6; and (d) a molecular weight distribution, (Mw/Mn) of from 2.5 to 4.0.

An activator-nucleator formulation comprising an activating effective amount of (A) an alkylaluminum(chloride) compound (compound (A)); and a nucleating effective amount of a compound (B) selected from at least one of compounds (B1) to (B3): (B1) calcium (1R,2S)-cis-cyclohexane-1,2-dicarboxylate (1:1); (B2) calcium stearate (1:2), and (B3) zinc stearate (1:2); wherein the compound (A) is effective for activating a Ziegler-Naha procatalyst to give a Ziegler-Natta catalyst; and wherein the compound (B) is effective for lowering isothermal crystallization peak time period of a semicrystalline polyethylene polymer made in a polymerization process by the Ziegler-Natta catalyst. A method of polymerizing ethylene, and optionally 0, 1, or more alpha-olefin comonomers, in a polymerization process conducted in a polymerization reactor, the method comprising contacting ethylene, and optionally 0, 1, or more alpha-olefin comonomers, with the Ziegler-Naha catalyst system to give a semicrystalline polyethylene polymer. The semicrystalline polyethylene polymer made by the method of polymerizing.

This disclosure relates to ethylene interpolymer compositions. Specifically, ethylene interpolymer products having: a Dilution Index (Y.sub.d) greater than 0; total catalytic metal 3.0 ppm; 0.03 terminal vinyl unsaturations per 100 carbon atoms, and; optionally a Dimensionless Modulus (X.sub.d) greater than 0. The disclosed ethylene interpolymer products have a melt index from about 0.3 to about 500 dg/minute, a density from about 0.869 to about 0.975 g/cm.sup.3, a polydispersity (M.sub.w/M.sub.n) from about 2 to about 25 and a CDBI.sub.50 from about 20% to about 97%. Further, the ethylene interpolymer products are a blend of at least two ethylene interpolymers; where one ethylene interpolymer is produced with a single-site catalyst formulation and at least one ethylene interpolymer is produced with a heterogeneous catalyst formulation.

Embodiments of methods for producing a trimodal polymer in a solution polymerization process comprise three solution polymerization reactors organized in parallel or in series.