摘要:
This invention enables the “bulk” oligomerization of ethylene (i.e. the oligomerization of ethylene in the presence of the oligomer product) using a catalyst system comprising 1) a very low concentration of a chromium catalyst and 2) a three part activator. The chromium catalyst contains a diphosphine ligand, preferably a so called P—N—P ligand. The activator includes an aluminoxane, trimethyl aluminum, and triethyl aluminum.
摘要:
Catalysts are activated in a dual reactor solution process by adding substoichiometric and superstoichiometric amounts of an ionic activator to an organometallic polymerization catalyst in a first and second reactor respectively. The new activation method allows one to alter process conditions in a favorably way with minimum impact to process economics. The new activation method also provides polymers which give films having improved optical properties.
摘要:
The oligomerization of ethylene using a chromium catalyst and an aluminoxane activator is well known. The undesired formation of polyethylene as a by-product is also known to occur during prior oligomerization processes. We have discovered that the use of an aluminoxane that is prepared by non-hydrolytic means provides a highly productive activator (co-catalyst) for ethylene oligomerization and mitigates the undesired formation of by-product polyethylene.
摘要:
The oligomerization of ethylene using a chromium catalyst having a heteroatomic ligand may be used to provide oligomerization products that are selective towards hexene and/or octene. However, such processes also typically produce some polymer as an undesirable by product. The present invention is directed towards improvements in the selective oligomerization of ethylene.
摘要:
The oligomerization of ethylene using a chromium catalyst having a bridged diphosphine ligand can produce a selective product distribution (to predominantly hexene or predominantly octene/hexene) when activated with an aluminoxane. The oligomerization reaction also produces polymer by product—particularly when the aluminoxane is provided in a non-aromatic solvent. The present invention mitigates this problem.
摘要:
A pair of shoes is provided that includes a left and a right shoe. The left shoe includes an upper having a left forefoot portion, the left forefoot portion having a lateral side with a portion thereof made of a first material and a medial side with a portion thereof made of a second material. The right shoe includes an upper having a right forefoot, the right forefoot having a medial side with a portion thereof made of the first material and a lateral side with a portion thereof made of the second material, wherein one of the first material and the second material provides more support than the other. The more supportive first material can include a polyurethane, such as TPU, a non-stretch synthetic material, or ceraprene. The second, less supportable material can be a light weight breathable mesh.
摘要:
New group 4 organometallic complexes are characterized by having a phosphinimine ligand and two or more cyclopentadienyl ligands. Certain of these complexes exhibit unusual behavior when examined by nuclear magnetic resonance (NMR) techniques. Well defined crystals of the inventive complexes have been isolated and analyzed by x-ray crystallography. The complexes have also been found to be polymerization catalysts which are surprisingly more active than their simple metallocene analogs.
摘要:
A dual reactor process for the solution (co)polymerization of ethylene uses a catalyst having a phosphinimine ligand in each of the two reactors. In a preferred embodiment, the two reactors are operated at different temperatures and/or with different cocatalyst systems (such as “alumoxanes” and “ionic activators”) for the preparation of linear low density polyethylene (“LLPDE”) having a broad molecular weight distribution. Certain LLDPE polymers of this invention have an outstanding balance of physical properties (high dart impact strength and tear strength) excellent optical properties and excellent processability.
摘要:
A new family of metallacycles, which are preferably zirconacycles, is characterized by having a unique halogenated substituent. The metallacycles are useful for the preparation of main group heterocycles, especially two novel families of heterocycles. The first new family of heterocycles preferably contains a halosilyl substituent. A preferred group of the second family of novel heterocycles contains a silyl group having a leaving group bonded thereto. The preferred group of these heterocycles is suitable for preparing novel organometallic complexes having a bridged bidentate heterocyclic ligand. These novel organometallic complexes may be used as catalyst components in olefin polymerization. The subject catalyst components are particularly well suited for use in the medium pressure solution process to prepare linear low density polyethylene.
摘要:
A catalyst system comprises an organometallic complex of a group 4 metal having a ketimide ligand. The organometallic complex preferably also contains a cyclic ligand which forms a delocalized pi-bond with the metal (such as a cyclopentadienyl-type ligand). Preferred organometallic complexes may be activated with a so-called "substantially non coordinating anion" to form a low cost cocatalyst system which is excellent for the preparation of olefin copolymers having both high molecular weight and very low density.