摘要:
A novel loop/slurry olefin polymerization process is provided which produces ultra high molecular weight ethylene homopolymers and ultra high molecular weight ethylene copolymers. Catalyst systems used are selected from the group consisting of inorganic oxide supported titanium-containing catalyst systems, inorganic oxide supported organo-zirconium catalyst systems and inorganic oxide supported organo-hafnium catalyst systems.
摘要:
Methods and systems for preparing catalyst, such as chromium catalysts, are provided. The valence of at least a portion of the catalyst sent to an activator is changed from Cr(III) to Cr(VI). The catalyst is prepared or activated continuously using a fluidization bed catalyst activator.
摘要:
A system and method for activating chromium catalyst, including: increasing temperature of a chromium catalyst at a first rate for a first period of time to a first temperature; and increasing temperature of the chromium catalyst at a second rate for a second period of time from the first temperature to a second temperature, wherein the first rate is greater than the second rate, and wherein the first period precedes the second period.
摘要:
New methods for activating chromium catalysts for polymerization processes decrease the amount of time required for activation and increase catalyst activity. Rapid heating to a first temperature is followed by a first hold period before heating to a higher second temperature and maintaining the second temperature for a second hold period. In one aspect, the overall activation process takes less than 10 hours.
摘要:
A copolymer of ethylene and a higher alpha olefin, preferably 1-hexene, can be produced using an activated chromium containing catalyst system and a cocatalyst selected from the group consisting of trialkylboron, trialkylsiloxyalutninum, and a combination of trialkylboron and thalkylaluminum compounds. The polymerization process must be carefully controlled to produce a copolymer resin having an exceptionally broad molecular weight distribution, extremely high PENT ESCR values, and a natural branch profile that impacts branching preferably into the high molecular weight portion of the polymer. The resulting copolymer resin is especially useful in high stiffness pipe applications.
摘要:
Polymerization processes for ethylene and at least one mono-1-olefin comonomer having from about three to eight carbon atoms per molecule in the presence of a twice-aged catalyst system comprising chromium supported on a silica-titania support and a trialkylboron compound is provided. Novel ethylene copolymers also are produced.
摘要:
A copolymer of ethylene and a higher alpha olefin, preferably 1-hexene, can be produced using an activated chromium containing catalyst system and a cocatalyst selected from the group consisting of trialkylboron, trialkylsiloxyaluminum, and a combination of trialkylboron and trialkylaluminum compounds. The polymerization process must be carefully controlled to produce a copolymer resin having an exceptionally broad molecular weight distribution, extremely high PENT ESCR values, and a natural branch profile that impacts branching preferably into the high molecular weight portion of the polymer. The resulting copolymer resin is especially useful in high stiffness pipe applications.
摘要:
An olefin polymerization process is provided comprising contacting an olefin monomer with chromium oxide on a titanium containing silica support having less than about 3 weight percent titanium in combination with an organoboron promoter. Polymers thus produced are useful for blow molding applications.
摘要:
A catalyst system for the polymerization of alpha-olefins comprising a chromium-containing catalyst and an yttrium-containing catalyst wherein the yttrium-containing catalyst is represented by the formula (Cp.sub.2 YX.sub.x).sub.y.M.sub.z L.sub.n, wherein Cp is cyclopentadienyl or cyclopentadienyl substituted with alkyl or alkyl silyl radical or radicals, X is a halogen, M is an alkali metal, L is a suitable electron donor ligand, x is 1 or 2, y is 1 or 2, z is 0 or 1, and n is a number corresponding to the value needed to form a stable complex, with the proviso that when y is 2, z and n are 0 is provided. Also disclosed is a polymerization process employing such a catalyst system, and novel olefin polymers. Polymers thus produced exhibit high bulk density and a broad molecular weight distribution.