摘要:
A method of modifying a Ziegler-Natta type polyolefin catalyst comprises contacting the Ziegler-Natta catalyst with olefin monomer to form a prepolymerized catalyst. The prepolymerized catalyst can comprise a reduced number of catalyst particles having a size of 40 microns or less. The prepolymerized catalyst can be used in a polymerization process to produce polymer fluff particles with a reduced number of polymer fluff fines than the Ziegler-Natta type catalyst.
摘要:
Disclosed is a bimodal Ziegler-Natta catalyzed polyethylene, having a density of from 0.930 g/cc to 0.960 g/cc, and a molecular weight distribution of from 10 to 25, wherein an article formed therefrom has a PENT of at least 1500. Also disclosed is a method of preparing a tubular article including obtaining a bimodal polyethylene having a density of from 0.930 g/cc to 0.960 g/cc and a molecular weight distribution of from 10 to 25, and processing the polyethylene under conditions where a specific energy input (SEI) is less than 300 kW·h/ton, and wherein the article has a PENT of at least 1500. Further disclosed is a method for controlling the degradation of polyethylene including polymerizing ethylene monomer, recovering polyethylene, extruding the polyethylene, and controlling the degradation of polyethylene by measuring the SEI to the extruder and adjusting throughput and/or gear suction pressure keep SEI less than 300 kW·h/ton, and forming an article.
摘要:
Propylene polymerization processes, polymers and films formed therefrom are described herein. The propylene polymerization processes generally include contacting propylene and an amount of ethylene with a first metallocene catalyst and a second metallocene catalyst within a polymerization reaction vessel to form a propylene based polymer, wherein the amount is an amount effective to form the propylene based polymer including from about 2 wt. % to about 6 wt. % ethylene, the second metallocene catalyst is capable of incorporating a greater amount of ethylene into the propylene based polymer than the first metallocene catalyst and wherein the first metallocene catalyst is capable of forming a propylene/ethylene random copolymer exhibiting a melting temperature that is greater than that of a propylene/ethylene random copolymer formed from the second metallocene catalyst.
摘要:
Supported catalyst systems and methods of forming the same are described herein. In one specific embodiment, the methods generally include providing an inorganic support material and contacting the inorganic support material with an aluminum fluoride compound represented by the formula AlFpX3-pBq to form an aluminum fluoride impregnated support, wherein X is selected from Cl, Br and OH−, B is H2O, p is selected from 1 to 3 and q is selected from 0 to 6. The method further includes contacting the aluminum fluoride impregnated support with a transition metal compound to form a supported catalyst system, wherein the transition metal compound is represented by the formula [L]mM[A]n; wherein L is a bulky ligand, A is a leaving group, M is a transition metal and m and n are such that a total ligand valency corresponds to the transition metal valency.
摘要:
Polyethylene modified by using radical initiators such as oxygen and peroxides sometimes has a yellow color which may be reduced or eliminated by incorporating additives such as polyethylene glycol, and/or neutralizing species such as alkali metal stearates, particularly calcium stearate, and zinc oxide.
摘要:
Injection stretch blow molded (ISBM) articles and processes for forming the same are described herein. The articles include a propylene based polymer having a melt flow rate of less than 10 g/10 min.
摘要:
Blown films and blow molded objects may be prepared using a polyethylene composition comprising a unimodal metallocene catalyzed polyethylene copolymer. The polyethylene copolymer has high melt fow rate and good melt strength allowing it to be useful in both extrusion and injection blow molding. Blown film prepared therewith has a high level of clarity.
摘要:
A method of forming a polyolefin catalyst component includes halogenating metal complexes. The metal complexes result from reacting a metal alkoxide with an alcohol-ether. A particular non-limiting example is a magnesium complex formed by reacting magnesium alkoxide with an ethylene alcohol-ether, and then chlorinating the magnesium complex. Catalyst components, catalysts, catalyst systems, polyolefin polymers and methods of making each are disclosed.
摘要:
It has been discovered that the amount of fluoropolymer additive used in a polyethylene resin affects the quality of finish of an article made with free surface polyethylene resins using chromium, Ziegler-Natta or metallocene catalysts. Reducing the amount of fluoropolymer increases the matte nature of the polymer finish, whereas increasing the amount of fluoropolymer increases the gloss nature of the finish. Introducing a peroxide or air in an increasing amount increases the long chain branching (LCB) of the polymer. Introducing an antioxidant in an amount to balance the peroxide amount can improve the melt strength of the polymer, and the amount of antioxidant is balanced with the amount of peroxide and/or air. The resultant polymer density ranges between about 0.960 and 0.962 g/cm3 inclusive, where the molecular weight distribution (MWD) of the polymer is greater than 3 and less than 6.
摘要翻译:已经发现,聚乙烯树脂中使用的含氟聚合物添加剂的量影响使用铬,齐格勒 - 纳塔或茂金属催化剂的用游离表面聚乙烯树脂制成的制品的表面光洁度。 减少含氟聚合物的量增加了聚合物涂饰的无光泽性质,而增加含氟聚合物的量增加了涂饰的光泽性质。 以增加的量引入过氧化物或空气增加聚合物的长链支化(LCB)。 引入抗氧化剂以达到平衡过氧化物量可以提高聚合物的熔体强度,并且抗氧化剂的量与过氧化物和/或空气的量平衡。 所得聚合物密度在约0.960至0.962g / cm 3之间,其中聚合物的分子量分布(MWD)大于3且小于6。
摘要:
A method comprising preparing a multi-component catalyst system comprising a catalyst and a cocatalyst, and adjusting the level of at least one component of the catalyst system to maintain a user-desired level of catalyst activity throughout a process, wherein the component comprises a catalyst activator and wherein the catalyst activator comprises the catalyst or the cocatalyst. A method comprising contacting a polymerization catalyst system comprising a Ziegler-Natta catalyst and a cocatalyst with a catalyst activator at least twice during a polymerization process, wherein the polymerization process is carried out in a reactor system comprising multiple reactor types.