Basell Polyolefine GmbH

A process for controlling the swell ratio of a polyethylene composition, made from or containing three or more polyethylene components and having a specified melt flow rate, including the steps of (a) preparing the polyethylene composition in a polymerization apparatus including three or more polymerization zones in the presence of a polymerization catalyst and hydrogen as molecular weight regulator and (b) selecting different ratios of hydrogen to ethylene in the polymerization zones, thereby forming the three or more polyethylene components which differ in average molecular weight and effecting the swell ratio of the polyethylene composition, wherein a first polyethylene component has the highest average molecular weight and a second polyethylene components has the second-highest average molecular weight.

A process for preparing a polyethylene composition made from or containing bimodal or multimodal polyethylene in an extruder device including the steps of (i) mixing a bimodal or multimodal polyethylene having a density from 0.940 g/cm 3 to 0.968 g/cm 3 , in the form of a polyethylene powder, with an additive, in a mixing device at a temperature from 10° C. to 100° C. without melting the polyethylene powder; (ii) melting and homogenizing the mixture within the extruder device, thereby forming a molten polyethylene composition; and (iii) pelletizing the molten polyethylene composition, and further (iv) adding a liquid made from or containing an organic peroxide, in an amount from 20 ppm to 200 ppm of organic peroxide with respect to the polyethylene powder, to the polyethylene powder at a position where mixing occurs and the polyethylene powder has a temperature of from 10° C. to 100° C.

A polymer blend made from or containing: A) from 65 to 98 wt. % of a first polyethylene component, having a density from 0.948 to 0.960 g/cm 3 , a Melt Index MIF from 30 to 100 g/10 min, and a Melt Flow Ratio MIF/MIP from 15 to 30; and B) from 2 to 35 wt. % of a second polyethylene component, having a density from 0.910 to 0.945 g/cm 3 and a Melt Index MIE of 0.1 to 3 g/10 min.

A process for preparing ethylene polymers including the step of polymerizing ethylene or copolymerizing ethylene and one or more comonomers at a temperature from 100° C. to 350° C. and a pressure of from 110 MPa to 350 MPa in a continuously operated tubular polymerization reactor, thereby yielding a reaction mixture, wherein the tubular polymerization reactor has a reactor cooling jacket for removing the heat of the reaction and a pressure control valve, the reaction mixture leaves the reactor through the pressure control valve, the reaction mixture then passes a post-reactor cooler equipped with a post-reactor cooling jacket, the reactor cooling jacket is provided with a reactor coolant having an inlet temperature and the post-reactor cooling jacket is provided with a post-reactor coolant having an inlet temperature, and the inlet temperature of the post-reactor coolant is independently controlled from the inlet temperature of the reactant coolant.

A process for polymerizing or copolymerizing one or more ethylenically unsaturated monomers with a controlled gas velocity of the gaseous reaction. A process for polymerizing or copolymerizing one or more ethylenically unsaturated monomers at temperatures from 100 to 350 ° C. and pressures in the range from 110 to 500 MPa, comprising the steps of: (a) compressing a gaseous reaction mixture in a hyper compressor, (b) providing the reaction mixture to each compressing stage through a suction pipe system, and (c) discharging the compressed reaction mixture from the compressing stage through a discharge pipe system.

A high-pressure polymerization system having a) a polymerization reactor and b) a reactor blow down system having b1) a reactor blow down vessel, having a circular design over a major portion P having a L/D-ratio in the range from 1.75 to 10.0 and containing an aqueous quenching medium, b2) a release line connecting the polymerization reactor with the reactor blow down vessel and having an outlet located above a maximum level for the aqueous quenching medium, b3) a first emergency valve in the release line to open and close fluid communication between the polymerization reactor and the reactor blow down system, and wherein the release line outlet has a joining piece having an angle (α) between the central axis and a tangent at the reactor blow down vessel in the range from 5° to 70° and the reactor blow down vessel has a vent stack containing a constricted section.

A process for the continuous production of a polyolefin polymer in a gas-phase polymerization reactor in the presence of a polymerization catalyst and an antistatic agent, including the steps of (a) providing a mixture of polyolefin particles and gas, (b) conveying the mixture through a pipe at a gas velocity of greater than or equal to 2 m/s, and (c) introducing an antistatic agent into the mixture.

A visbreaking process, in which either vacuum is applied or not, using low density polyethylene recyclates (rLDPE) comprising also amounts of linear low density polyethylene (rLLDPE). Application of a low energy-intake and vacuum during visbreaking treatment, by limiting temperature and RPM of the extruder's screw, a superior visbroken material is obtained, suitable for films with less gels. A method and visbroken, degassed LDPE recyclate having less odor. The visbroken LDPE recyclate shows only minor increase in or almost the same MFR compared to the starting material, and only moderate increase of density, by a removing of at least 90% of the defects and gels and showing superior optical performance when processed to films.

A lower-energy visbreaking process with lower energy-intake of the polymer for visbreaking of low density polyethylene recyclates, derived from film waste material, via visbreaking thermal and mechanical processing conditions in an extruder, performed for at least two different temperatures, greater than 220° C. and lower than 340° C. Providing a visbroken LDPE with a low increase in MFR compared to the starting material, and lower increase of density. Resulting in a visbroken LDPE material, showing superior optical performance when processed to film, with second generation gels per cm 2 .

A process for preparing an ethylene polymer in a suspension polymerization including the steps of separating the formed suspension of ethylene polymer particles in a solid-liquid separator into ethylene polymer particles and mother liquor, transferring a first part of the mother liquor into a work-up section including an evaporation unit for producing a wax-depleted portion of the mother liquor, wherein a protic agent is added to the part of the mother liquor which is transferred into the work-up section, and recycling a first part of the wax-depleted portion of the mother liquor to the polymerization reactor or the series of polymerization reactors.