Abstract:
The present disclosure relates to a continuous process for the preparation of ethylene homopolymers or ethylene copolymers comprising polymerizing ethylene or copolymerizing ethylene and one or more other olefins in the presence of a chromium catalyst in a gas-phase polymerization reactor which is equipped with a cycle gas line for withdrawing reactor gas from the reactor, leading the reactor gas through a heat-exchanger for cooling and feeding the reactor gas back to the reactor, wherein the polymerization is carried out at a temperature from 30° C. to 130° C. and a pressure of from 0.1 to 10 MPa and an aliphatic carboxylic acid ester having from 8 to 24 carbon atoms is added.
Abstract:
A process for the preparation of an ethylene polymer including the step of polymerizing ethylene or copolymerizing ethylene and one or more other olefins in the presence of a Phillips-type chromium catalyst in a gas-phase polymerization reactor containing a reactor bed of particulate polymer, wherein the gas-phase polymerization reactor is equipped with a cycle gas line, wherein the reactor gas returned to the polymerization reactor through the cycle gas line has been condensed in part and the amount of liquid in the returned reactor gas is from 0.5 wt. % to 10 wt. % based upon the total weight of the reactor gas/liquid composition, the polymerization is carried out at from 108° C. to 125° C., and an aluminum alkyl is fed into the polymerization reactor in an amount in the range of from 0.0025 mole to 0.1 mole per ton of dosed ethylene.
Abstract:
A polyethylene composition having the following features: 1) density from about 0.945 to about 0.958 g/cm3, determined according to ISO 1183 at 23° C.; 2) ratio MIF/MIP from about 20 to about 43; 3) MIF from about 4.0 to less than about 8.5 g/10 min.; 4) HMWcopo index from about 3.5 to about 20; and 5) long-chain branching index, LCBI, equal to or lower than about 0.82. The polyethylene composition can be used to produce blown films.
Abstract:
The present disclosure relates to a continuous process for the preparation of ethylene homopolymers or ethylene copolymers comprising polymerizing ethylene or copolymerizing ethylene and one or more other olefins in the presence of a chromium catalyst in a gas-phase polymerization reactor which is equipped with a cycle gas line for withdrawing reactor gas from the reactor, leading the reactor gas through a heat-exchanger for cooling and feeding the reactor gas back to the reactor, wherein the polymerization is carried out at a temperature from 30° C. to 130° C. and a pressure of from 0.1 to 10 MPa and an aliphatic carboxylic acid ester having from 8 to 24 carbon atoms is added.
Abstract:
A process for preparing a polyolefin, including polymerizing olefins in the presence of an antistatic agent made from or containing an alkylene oxide derived polymer made from or containing in average from about 10 to about 200 repeating units —(CH2—CHR—O)— with R being hydrogen or an alkyl group having from 1 to 6 carbon atoms, wherein the alkylene oxide derived polymer is a random copolymer of ethylene oxide and other alkylene oxides and a ratio of n:m is in the range of from 6:1 to 1:1, wherein (n) is the average number of repeating units —(CH2—CH2—O)— derived from ethylene oxide and (m) is the average number of repeating units —(CH2—CHR′—O)— derived from the other alkylene oxides with R′ being an alkyl group having from 1 to 6 carbon atoms, and the end groups of the alkylene oxide derived polymer are —OH groups.
Abstract:
A slurry polymerization process for the preparation of polyethylene in a reactor cascade of two or more polymerization reactors including the steps of feeding to a polymerization reactor amounts of ethylene, of a Ziegler catalyst, of fresh aluminum alkyl and of a diluent; feeding the slurry product withdrawn from the polymerization reactor to a second polymerization reactor; and feeding additional amounts of ethylene and of diluent wherein the ethylene is first passed through an ethylene purification unit, which reduces at least the concentration of carbon monoxide, carbon dioxide, oxygen, acetylene and water contained in the ethylene, before it is fed to the two or more polymerization reactors of the reactor cascade.
Abstract:
A process for the gas-phase polymerization of ethylene or a mixture of ethylene and one or more 1 olefins in the presence of a polymerization catalyst system comprising the steps a) feeding a solid catalyst component, which was obtained by contacting at least a magnesium compound and a titanium compound, to a continuously operated apparatus and contacting the solid catalyst component with an aluminum alkyl compound at a temperature of from 0° C. to 70° C. in a way that the mean residence time of the solid catalyst component in contact with the aluminum alkyl compound is from 5 to 300 minutes; b) transferring the catalyst component formed in step a) into another continuously operated apparatus and prepolymerizing it with ethylene or a mixture of ethylene and one or more 1 olefins in suspension at a temperature of from 10° C. to 80° forming polymer in an amount of from 0.2 to 25 g polymer/g of solid catalyst component in a way that the mean residence time of the solid catalyst component in the apparatus is from 5 minutes to 3 hours; and c) transferring the prepolymerized catalyst component formed in step b) into a gas-phase polymerization reactor and polymerizing ethylene or a mixture of ethylene and one or more 1 olefins in the presence of the prepolymerized catalyst component at temperatures of from 40° C. to 120° C. and pressures of from 0.1 to 10 MPa.
Abstract:
A process for the preparation of polyolefins by polymerizing olefins at temperatures of from 20 to 200° C. and pressures of from 0.1 to 20 MPa in the presence of a polymerization catalyst and an antistatically acting composition in a polymerization reactor, wherein the antistatically acting composition is a mixture comprising an oil-soluble surfactant and water and the use of an antistatically acting composition comprising an oil-soluble surfactant and water as antistatic agent for the polymerization of olefins at temperatures of from 20 to 200° C. and pressures of from 0.1 to 20 MPa in the presence of a polymerization catalyst.
Abstract:
The present disclosure relates to a polyethylene composition with improved swell ratio and mechanical properties for use in preparing blow-moulded articles and having the following features: 1) a density from 0.945 to less than 0.952 g/cm3; 2) an MIF/MIP ratio from 15 to 30; 3) a Shear-Induced Crystallization Index (SIC) from 2.5 to 5.5.
Abstract:
The invention relates to a polyethylene molding composition having a multimodal molar mass distribution particularly suitable for blow molding films having a thickness in the range from 8 to 200 μm. The molding composition has a density at a temperature of 23° C. in the range from 0.953 to 0.960 g/cm3 and an MFR190/5 of the final product after extrusion in the range from 0.10 to 0.50 dg/min. The composition comprises from 30 to 60% by weight of a first ethylene polymer fraction made of a homopolymer A having a first molecular weight, from 22 to 40% by weight of a second ethylene polymer fraction made of a further homopolymer or first copolymer B of ethylene and at least one first comonomer from the group of olefins having from 4 to 8 carbon atoms, the first copolymer B having a second molecular weight higher than the first molecular weight, and from 10 to 30% by weight of a third ethylene polymer fraction made of a second copolymer C having a third molecular weight higher than the second molecular weight. The molding composition of the invention allows to produce thin films having improved processability without impairing the mechanical properties.