Abstract:
Feeding a supported antistatic compound that does not comprise a transition-metal-based catalyst component to an olefin polymerization reactor allows avoiding the formation of polymer agglomerates in the reactor while at the same time minimizing negative effects on catalyst yield.
Abstract:
A solution process for polymerizing one or more α-olefins of the formula CH2=CHR, where R is H or an alkyl radical C1-C18, to produce a polymer that is soluble in the reaction medium, comprising the steps of: - continuously polymerizing in a liquid phase the α-olefin in the presence of a catalyst system based on a transition metal compound to obtain a solution of polymer in the reaction medium; - the polymeric solution obtained from step a) is then mixed in one or more mixing stages with an aqueous mixture comprising one or more organic compounds having at least a hydroxy or epoxy group, said aqueous mixture having a dynamic viscosity at 30°C higher than 50 cP (centiPoise).
Abstract:
A process for the gas-phase polymerization of one or more alpha-olefins in the presence of a polymerization catalyst system, the process comprising: a) contacting in a continuous way a gas comprising one or more of said alpha-olefins with said catalyst system in a gas-phase tubular reactor at a temperature from 30°C to 130°C in order to obtain a polymerization degree up to 500 grams per gram of catalyst system; b) feeding in continuous the prepolymer from step a) to a successive gas-phase polymerization reactor; wherein said gas-phase tubular reactor has a length/diameter ratio higher than 100.
Abstract:
Process for preparing a broad molecular weight polyethylene by polymerizing ethylene in the presence of a polymerization catalyst, the process comprising the following steps, in any mutual order: a) polymerizing ethylene, optionally together with one or more a-olefinic comonomers having from 3 to 12 carbon atoms, in a gas-phase reactor in the presence of hydrogen, b) copolymerizing ethylene with one or more a-olefinic comonomers having from 3 to 12 carbon atoms in another gas-phase reactor in the presence of an amount of hydrogen less than step a), where in at least one of said gas-phase reactors the growing polymer particles flow upward through a first polymerization zone under fast fluidization or transport conditions, leave said first polymerization zone and enter a second polymerization zone through which they flow downward under the action of gravity.