Abstract:
A process for making an ethylene homopolymer in the presence of an oxide-supported chromium catalyst is disclosed. A small amount of an α-olefin contacted with the catalyst before polymerizing ethylene or introduced into an ethylene homopolymerization unexpectedly boosts process productivity. When used at part per million levels, the α-olefin improves productivity while maintaining desirable polymer properties. The invention is particularly valuable for making HDPE resins useful for blow molding applications.
Abstract:
The present invention provides an ethylene copolymer resin that has unique melt elastic properties not observed in ethylene copolymers heretofore known. Specifically, the ethylene copolymer resin of the present invention when in pelletized form has a reduction in melt elasticity (ER) of 10% or more to a final value of 1.0 or less upon rheometric low shear modification or solution dissolution. Moreover, the resin of the present invention when in reactor-made form exhibits at least a partially reversible increase of 10% or more in ER when pelletizing the same. An ethylene polymerization catalyst, a process of preparing the ethylene copolymer resin and a high-impact film are also provided herein.
Abstract:
A process for producing olefin polymer composites having improved melt strength and other improved physical characteristics is provided. The process is a solution process wherein an organically modified clay is intimately incorporated, at low levels and without the use of compatibilizing agents, into an olefin polymer base resin.
Abstract:
A process for the polymerization of olefins is disclosed. A boraaryl catalyst precursor and an activator are used in the presence of a silane modifier. A low level of silane modifier enhances the activity of the catalyst.
Abstract:
Supported heterometallocene catalysts wherein the support is a particulate polymeric material are provided. The catalysts have a transition metal complex containing at least one anionic, polymerization stable heteroatomic ligand associated with the transition metal and a boron activator compound deposited on the support. Polymeric supports used for the heterometallocene catalysts of the invention are homopolymers of ethylene and copolymers of ethylene and C3-8 &agr;-olefins.
Abstract:
The present invention is directed to a novel halosilane cocatalyst component which, when used in conjunction with an aluminum containing cocatalyst, is effective in increasing the activity of a supported magnesium/titanium containing catalyst in the polymerization of ethylene and .alpha.-olefins. In addition to the increased catalytic activity, the polymers produced by the present invention are characterized as having an unexpected enhancement in the polymer melt index. Thus, the catalyst system of the instant invention represents an advancement in the art in view of the combination of increased activity, i.e., yield of polymer produced, and physical properties of the polyolefin product.In another aspect of the present invention, a process for polymerizing .alpha.-olefins is disclosed. In this process at least one olefin is polymerized under olefin polymerization conditions utilizing the catalyst system of the present invention, which includes the solid catalyst component of the present invention, along with the first cocatalyst, an aluminum-containing compound, and the second cocatalyst, a halosilane compound.
Abstract:
The present invention is directed to a novel halosilane cocatalyst component which may be used in conjunction with an aluminum-containing cocatalyst to provide enhanced catalytic activity of a vanadium based solid catalyst component in the polymerization of .alpha.-olefins. In addition to the enhancement in the catalytic activity obtaining using the present catalyst system, the resultant polymer produced by the present invention exhibits improved physical properties compared with polymers produced by prior art vanadium based catalyst systems. Thus, the catalyst system of the instant invention represents an advance in the art in view of the combination of increased catalytic activity, i.e. yield of polymer produced, and enhanced physical properties of the polyolefin produced.In accordance with the present invention, a catalyst system is provided which comprises a solid catalyst component and a halosilane cocatalyst component. The solid catalyst component of the present invention is the product formed by admixing a solid inorganic oxide, an organometallic compound, a vanadium-containing compound and an organic reagent.In another aspect of the present invention, a process of the polymerization of .alpha.-olefins is disclosed. In this process at least one olefin is polymerized under olefin polymerization catalyst utilizing the catalyst system of the present invention, which includes the solid catalyst component of the present invention, and a cocatalyst selected from the group consisting of halosilane compounds and admixtures thereof with aluminum compounds.
Abstract:
A method of modifying a polyethylene is disclosed. In the method ethylene or a mixture of ethylene and a C3-C10 α-olefin is polymerized in an organic solvent with a Ziegler or single-site catalyst to form an initial polyethylene solution. The initial polyethylene solution is then reacted with a free radical initiator to produce a modified polyethylene. The modified polymer has an enhanced melt elasticity and increased long chain branching index, and is essentially free of gel.
Abstract:
A process for polymerizing olefins is disclosed. The process uses a hydrosilane in a polymerization catalyzed by an open architecture, bridged indenoindolyl organometallic complex and an activator. Polyolefins from the process have increased molecular weight.
Abstract:
A method for modifying a high-density polyethylene (HDPE)-clay nanocomposite is disclosed. The method comprises shearing a melt of the nanocomposite at an effective shear rate. The modified nanocomposite shows significantly increased complex melt viscosity, storage modulus, and loss modulus.