Abstract: The present invention relates to a method for producing a catalyst slurry blend suitable for polymerizing ethylene in an ethylene polymerization loop reactor for obtaining an at least trimodal polyethylene product, comprising the steps of: transferring a first ethylene polymerization catalyst at a first mass flow rate to a mixing vessel, simultaneously transferring a second ethylene polymerization catalyst at a second mass flow rate to said mixing vessel, thereby in situ providing a catalyst slurry blend, wherein said second ethylene polymerization catalyst is different from the first ethylene polymerization catalyst, adjusting and monitoring said first and second mass flow rates, thereby obtaining said catalyst slurry blend at a concentration suitable for polymerizing ethylene, and feeding said catalyst slurry blend to an ethylene polymerization double loop reactor producing said at least trimodal polyethylene product.

Abstract: The present invention relates to a process for preparing a bimodal polyethylene product in a single loop reactor, comprising polymerizing ethylene monomer and optionally one or more olefin co-monomers in the presence of a single heterogeneous polymerization catalyst consisting of a metallocene-alumoxane catalyst immobilized on a porous support wherein said metallocene comprises only one transition metal. Said polymerization catalyst consists of two physically different fractions of support particles onto which said metallocene-alumoxane catalyst is immobilized.

Abstract: The present invention relates to a method for optimizing the sequential feeding of at least two ethylene polymerization catalysts to an ethylene polymerization reactor, comprising: transferring to a mixing vessel a first ethylene polymerization catalyst and a first diluent, decreasing the concentration of said first ethylene polymerization catalyst in said mixing vessel, transferring to said mixing vessel a second ethylene polymerization catalyst and a second diluent, progressively replacing said first ethylene polymerization catalyst by said second ethylene polymerization catalyst and said first diluent by said second diluent, increasing the concentration of said second ethylene polymerization catalyst in said mixing vessel, sequentially transferring said first ethylene polymerization catalyst and said second ethylene polymerization catalyst from said mixing vessel to an ethylene polymerization reactor.

Abstract: A high pressure polymerization process to form an ethylene-based polymer comprises the steps of: A. Injecting a first feed comprising ethylene and optionally a chain transfer agent system (CTA system) into a first autoclave reactor zone operating at polymerization conditions to produce a first zone reaction product, the CTA system of the first reactor zone having a transfer activity Z1; and B. (1) Transferring at least part of the first zone reaction product to a second reactor zone selected from a second autoclave reactor zone or a tubular reactor zone and operating at polymerization conditions, and, optionally, (2) freshly injecting a second feed into the second reactor zone to produce a second zone reaction product, with the proviso that the second reactor zone contains a CTA system having a transfer activity Z2; and with the proviso that the ratio of Z1/Z2 is less than 1.

Abstract: The invention relates to a process for the preparation of a particulate bimodal polyethylene product having a median particle diameter of less than 300 ?m in a serially connected double loop reactor, wherein said polymerization catalyst applied in the polymerization process comprises a particulate metallocene-alumoxane catalyst immobilized on a porous silica support, wherein said polymerization catalyst has a median particle diameter of less than 50 ?m; and whereby the ratio of the median particle diameter of the obtained bimodal polyethylene product to the median particle diameter of the applied polymerization catalyst is less than 30.

Abstract: The present invention relates to a process for preparing a polyamide based on dicarboxylic acids and diamines, comprising the following stages: A) providing an aqueous monomer mixture composed of dicarboxylic acids and diamines, where the molar ratio of dicarboxylic acids to diamines is adjusted such that, at the outlet of stage C), there is a molar deficiency of dicarboxylic acids or diamines of 1 to 10 mol%, based on the respective other component, B) transferring the aqueous mixture from stage A) into a continuous evaporator reactor in which diamines and dicarboxylic acids are converted at a temperature in the range from 100 to 370° C. and a pressure in the range from 1 to 50 bar, C) transferring the mixture from stage B) into a separator which is operated at a temperature in the range from 100 to 370° C.

Abstract: Process for the preparation of ethylene homopolymers or copolymers in the presence of free-radical polymerization initiators at from 100° C. to 350° C. and pressures in the range of from 160 MPa to 350 MPa in a tubular reactor with at least two spatially separated initiator injection points, wherein injecting initiator rises the temperature of the reaction mixture in the reaction zone following the injection point, and the first initiator injection point of the tubular reactor is not provided with initiator or is provided with so little initiator that the temperature of the reaction mixture does not rise more than 20° C.

Abstract: The present invention provides dual catalyst systems containing a metallocene catalyst and a hydrogen scavenging catalyst, and polymerization processes employing these dual catalyst systems. Due to a reduction in hydrogen levels in the polymerization processes, olefin polymers produced from these polymerization processes may have a higher molecular weight, a lower melt index, and higher levels of unsaturation.

Abstract: A process for polymerizing or oligomerising a hydrocarbon includes feeding at a low level a liquid hydrocarbon reactant into a bulk liquid phase comprising polymeric or oligomeric product admixed with a catalyst. The liquid hydrocarbon reactant is allowed to vaporise to form bubbles rising through the bulk liquid phase and to polymerise or oligomerise to form the polymeric or oligomeric product, with the rising bubbles creating turbulence in the bulk liquid phase, thereby mixing the bulk liquid phase. Gaseous components comprising any unreacted vaporised hydrocarbon reactant and any gaseous product that may have formed are withdrawn from a head space above the bulk liquid phase. Liquid phase from the bulk liquid phase is withdrawn to maintain the bulk liquid phase at a desired level.

Abstract: A process for the preparation of a chromium-type supported olefin polymerization catalyst. A fluidized bed of support particles in an inert carrier gas is established. A chromium (III) compound is added to the fluidized support particles to provide a supported catalyst component. The supported catalyst component is activated to convert at least a portion of the chromium (III) to Chromium (VI). The chromium (III) containing particles may be recovered from the fluidized bed and then activated or they may be activated in the fluidized bed. Also the support particles can be treated in the fluidized bed with other treatment agents. The support particles may be pretreated with a solution of a boron treating agent prior to incorporation of the support in the fluidized bed.

Abstract: The present invention provides polymerization processes utilizing a catalyst system containing an ansa-metallocene and a second metallocene compound for the production of olefin polymers.

Abstract: A process for making an ethylene homopolymer in the presence of an oxide-supported chromium catalyst is disclosed. A small amount of an ?-olefin contacted with the catalyst before polymerizing ethylene or introduced into an ethylene homopolymerization unexpectedly boosts process productivity. When used at part per million levels, the ?-olefin improves productivity while maintaining desirable polymer properties. The invention is particularly valuable for making HDPE resins useful for blow molding applications.

Abstract: Disclosed is a process for producing a thermoplastic copolymer, which comprises step of supplying a monomer mixture (a) to a loop reactor continuously to produce a copolymer (A), the monomer mixture (a) comprising an aromatic vinyl monomer (a1), a vinyl cyanide monomer (a2) and an N-substituted maleimide monomer (a3). The process enables the production of a thermoplastic copolymer which has an excellent balance among physical properties such as heat resistance, color and flow property, reduces the amount of bleeding that may cause mold staining during molding processing and has excellent handleability and productivity.

Abstract: A novel LDPE from radical, high pressure polymerization is devised.

Abstract: The present invention provides a multiple loop reactor suitable for polymerizing olefins comprising at least two interconnected loop reactors, whereby said connection essentially consists of one or more transfer lines suitable for transferring polymer slurry from a reactor to another reactor and whereby said transfer line extends substantially horizontally. The invention further relates to a process for producing olefin polymers in a multiple loop reactor according to the invention. The invention also relates to the use of a transfer line for transferring polymer slurry from a reactor to another reactor in a multiple loop reactor comprising at least two interconnected loop reactors, whereby said transfer line extends substantially horizontally.

Abstract: This invention relates to catalyst compositions, methods, and polymers encompassing at least one first Group 4 metallocene compound comprising bridging ?5-cyclopentadienyl-type ligands, in combination with at least one second Group 4 metallocene with non-bridging ?5-cyclopentadienyl-type ligands, typically in combination with at least one cocatalyst, and at least one activator. The compositions and methods disclosed herein provide ethylene polymers with a bimodal molecular weight distribution.

Abstract: The present invention provides polymerization catalyst compositions employing half-metallocene compounds with a heteroatom-containing ligand bound to the transition metal. Methods for making these hybrid metallocene compounds and for using such compounds in catalyst compositions for the polymerization of olefins also are provided.

Abstract: A process for producing polyolefins, which includes polymerizing at least one olefin monomer, separating at least a part of the reaction mixture, dividing the separated reaction mixture into a polymer-lean fraction and a polymer-rich fraction, and subjecting at least a part of the polymer-lean fraction to a purification step prior to recycling back to the polymerization of at least one olefin monomer. The obtained polyolefins particularly have a low content of volatile low molecular weight compounds, a low content of low-molecular weight polyolefin waxes and a low content of residues derived from the catalyst employed.

Abstract: Process for the preparation of ethylene homopolymers or copolymers in a high pressure reactor with at least two spatially separated initiator injection points by polymerizing ethylene and optionally further monomers in the presence of at least two different mixtures of free-radical polymerization initiators at from 100° C. to 350° C. and pressures in the range of from 160 MPa to 350 MPa, wherein the process comprises the following steps: a) providing at least two different initiators as solution in a suitable solvent or in liquid state, b) mixing the initiators and optionally additional solvent in at least two static mixers and c) feeding each of the mixtures to a different initiator injection point of the high pressure reactor, and apparatus for feeding initiator mixtures to a high pressure reactor with at least two spatially separated initiator injection points.

Abstract: A polyolefin has 1) a density in the range of 0.93 to 0.97 g/cm3, 2) a BOCD (Broad Orthogonal Co-monomer Distribution) index defined by a given equation in the range of 1 to 5, and 3) a molecular weight distribution (weight average molecular weight/number average molecular weight) in the range of 4 to 10. A supported hybrid metallocene catalyst comprises a first metallocene compound represented by a first given formulae, a second metallocene compound represented by one of three given formulae, and a support.

Abstract: The present invention relates to a process for the polymerization of an olefin monomer. In particular, the present invention relates to a process for the polymerization of an olefin monomer and one or more optional comonomers in presence of a polymerization catalyst and hydrogen, said process being characterized by an improved control of the hydrogen concentration in the polymerization reactor. In addition, the present invention provides for an improved hydrogen feeding system to a polymerization reactor. Furthermore, the present invention provides for a polymerization reactor comprising such an improved hydrogen feeding system.

Abstract: Process for producing a multimodal polyethylene in at least two reactors connected in series, in which 20-80 wt % of a first polymer is made in suspension in a first reactor and 80-20 wt % of a second polymer is made in suspension in a second reactor in the presence of the first polymer, and a stream or slurry containing the resulting polymer is withdrawn from the second reactor and transferred to a flash tank operating at a pressure and temperature such that at least 50 mol % of the liquid component of the slurry, or the non-polymer component of the stream entering the flash tank, is withdrawn from the flash tank as a vapour, wherein the concentration in the stream or slurry entering the flash tank of components having a molecular weight below 50 g/mol, Clights (mol %), satisfies the equation Clights<7+0.07(40?Tc)+4.4(Pc?0.8)?7(CH2/CEt) where Tc and Pc are respectively the temperature (in ° C.

Abstract: A system and method for measuring pressure and flow rate of polymer slurry circulating in a loop reactor. For flow rate measurement, the loop reactor has a pressure tap on an outside radius of an elbow of the loop and a pressure tap on an inside radius of the elbow. The pressure taps incorporate diaphragms. Sensing legs couple the pressure taps with a differential pressure meter configured to provide a signal indicative of the flow rate of the polymer slurry. For pressure measurement, pressure taps without diaphragms at the loop reactor wall may be disposed at various points along the loop reactor, the pressure taps coupled to pressure sensing lines. A diluent flush line having a screen disposed therein may provide diluent to the pressure taps. The screen may reduce fouling of the pressure tap and sensing line with solids from the reactor.

Abstract: Process for producing a multimodal polyethylene in at least two loop reactors connected in series. In the process 20-80 wt % of a high molecular weight (HMW) polymer is made in suspension in a first reactor and 20-80 wt % of a low molecular weight (LMW) polymer is made in suspension in a second reactor, one polymer being made in the presence of the other in either order. The ratio of the average activity in the LMW reactor to the average activity in the HMW reactor is from 0.25 and 1.5, where average activity in each reactor is defined as the rate of polyethylene produced in the reactor (kgPE/hr)/[ethylene concentration in the reactor (mol %)×residence time in the reactor (hours)×feed rate of catalyst into the reactor (g/hr)], residence time being defined as the mass of the polymer in the reactor (kg)/the output rate of polymer from the reactor (kg/hr), and the volumes of the two reactors differ by less than 10%.

Abstract: A process for making an ethylene homopolymer in the presence of an oxide-supported chromium catalyst is disclosed. A small amount of an ?-olefin contacted with the catalyst before polymerizing ethylene or introduced into an ethylene homopolymerization unexpectedly boosts process productivity. When used at part per million levels, the ?-olefin improves productivity while maintaining desirable polymer properties. The invention is particularly valuable for making HDPE resins useful for blow molding applications.

Abstract: The present invention provides polymerization catalyst compositions employing novel dinuclear metallocene compounds. Methods for making these new dinuclear metallocene compounds and for using such compounds in catalyst compositions for the polymerization and copolymerization of olefins are also provided.

Abstract: The present invention provides polymerization catalyst compositions employing novel heterodinuclear metallocene compounds. Methods for making these new dinuclear metallocene compounds and for using such compounds in catalyst compositions for the polymerization of olefins are also provided.

Abstract: A polyester production system employing a vertically elongated esterification reactor. The esterification reactor of the present invention is an improvement over conventional CSTR esterification reactors because, for example, in one embodiment, the reactor requires little or no mechanical agitation. Further, in one embodiment, the positioning of the inlets and outlets of the reactor provides improved operational performance and flexibility over CSTRs of the prior art.

Abstract: The invention relates to a method of operating a high pressure ethylene polymerization unit comprising a tubular reactor, the method characterized in that the electrical conductivity of the aqueous cooling medium is monitored in at least one location. Furthermore, the invention also covers a high pressure ethylene polymerization unit comprising a tubular reactor, the unit characterized in that one or more cooling circuits comprise an electrical conductivity meter. The use of such a polymerization unit is also disclosed.

Abstract: The present invention relates to a process for cooling a polymerization reaction for producing polyolefin comprising the steps of: (a) thermally contacting said polymerization reaction with a cooling fluid such that the cooling fluid removes thermal energy from said reaction, (b) thermally contacting said cooling fluid with a working fluid thereby recovering said thermal energy from said cooling fluid in said working fluid, and (c) thermally contacting the cooling fluid obtained in step (b) with the polymerization reaction thereby cooling said reaction, wherein the working fluid is phase converted thereby providing energy in the form of heat and/or electricity and/or mechanical power back to the polyolefin production process. Said invention also relates to a polymerization process for producing olefin polymers in a reactor, and also relates to a process for energy optimization of energy consumption in a polymerization process and to a polymerization unit.

Abstract: Techniques are provided for producing polymer particles of a size just slightly larger than the size of polymer fines. The technique may prevent or limit the occurrence of reactor fouls associated with large polymer particles. The technique also may provide a greater weight percentage of solids in the reactor. The desired polymer particle size may be achieved by employing a catalyst having particles of a size determined based on the expected catalyst productivity. In certain embodiments, the catalyst particle size may be determined based on the expected catalyst productivity, the polymer particle density, the catalyst particle density, and/or the polymer particle size.

Abstract: This invention discloses caps and closures produced by injection moulding with a bimodal high density polyethylene (HDPE) resin comprising a low molecular weight, high density polyethylene fraction substantially free of comonomer and a high molecular weight, low density polyethylene fraction, having a molecular weight distribution of at least 3.5, preferably greater than 4.0, prepared in two reactors connected in series in the presence of a metallocene-containing catalyst system, wherein the metallocene comprises a bisindenyl or a bis-tetrahydrogenated-indenyl component.

Abstract: Method of reducing fouling in an elastomer polymerization process that includes providing a reactor capable of housing an industrial-scale elastomer polymerization reaction, and applying a mechanical force to the reactor so as to create a vibration in at least one wall of the reactor, in which fouling is reduced in the reactor. In one embodiment the reaction is an industrial scale butyl polymerization reaction and the reactor is a butyl polymerization reactor.

Abstract: Process for producing a multimodal polyethylene in at least two reactors connected in series, in which 20-80 wt % of a high molecular weight (HMW) polymer is made in suspension in a first reactor and 20-80 wt % of a low molecular weight (LMW) polymer is made in suspension in a second reactor in the presence of the HMW polymer, wherein the solids concentration in the second LMW reactor, defined as the mass of polymer divided by the total mass of slurry, is at least 35 wt %, most preferably between 45 wt % and 60 wt %, and/or the ratio of solids concentration in the first reactor to that in the second reactor is maintained at less than 1.0, preferably between 0.6 and 0.8, and further wherein the volume of the second reactor is at least 10%, preferably at least 30% and more preferably at least 50% greater than the volume of the first reactor.

Abstract: Process for producing a multimodal polyethylene in at least two reactors connected in series, in which 20-80 wt % of a high molecular weight (HMW) polymer is made in suspension in a first reactor and 20-80 wt % of a low molecular weight (LMW) polymer is made in suspension in a second reactor. The ratio of the average activity in the LMW reactor to the average activity in the HMW reactor is from 0.25 and 1.5, where average activity in each reactor is defined as the rate of polyethylene produced in the reactor (kgPE/hr)/[ethylene concentration in the reactor (mol %)×residence time in the reactor (hours)×feed rate of catalyst into the reactor (g/hr)], residence time being defined as the mass of the polymer in the reactor (kg)/the output rate of polymer from the reactor (kg/hr). The volume of the second reactor is at least 10% greater than the volume of the first reactor, and the ratio of length to diameter of the first reactor, L/D(1), is greater than that of the second reactor, L/D(2).

Abstract: Polymerisation process in which polyethylene is produced in slurry in a polymerisation reactor in the presence of a Ziegler Natta catalyst and an activator, and a stream or slurry containing the polymer is withdrawn from the reactor and transferred to a flash tank operating at a pressure and temperature such that at least 50 mol % of the liquid or non-polymer component of the stream entering the flash tank or slurry is withdrawn from the flash tank as a vapour and at least 98 mol % of the vapour withdrawn from the flash tank is capable of being condensed at a temperature of between 15 and 50° C., without compression. A by-product suppressor, which reduces the amount of by-product formed per unit of polyethylene produced by at least 10%, compared with an identical polymerisation process where the by-product suppressor is not present, is used in the reactor. The molar ratio of the by-product suppressor added to the reactor to titanium added to the reactor is between 0.2 and 1.

Abstract: The present invention relates to olefin polymers having associative groups containing nitrogen heterocyclic compounds, to hot-melt adhesives including such polymers, and to method for producing same. Specifically, the invention relates to a polymer comprising units from ethylene and from a monomer having associative groups, said monomer including a polymerizing reactive group and an associative group containing nitrogen heterocyclic compounds.

Abstract: The present techniques relate to catalyst compositions, methods, and polymers encompassing a Group 4 metallocene compound comprising bridging ?5-cyclopentadienyl-type ligands, typically in combination with a cocatalyst, and a activator. The compositions and methods presented herein include ethylene polymers with low melt elasticity.

Abstract: The present invention provides polymerization catalyst compositions employing half-metallocene compounds with a heteroatom-containing ligand bound to the transition metal. Methods for making these hybrid metallocene compounds and for using such compounds in catalyst compositions for the polymerization and copolymerization of olefins are also provided.

Abstract: The present invention provides polymerization processes utilizing an ansa-metallocene catalyst system for the production of olefin polymers. Polymers produced from the polymerization processes have properties that vary based upon the presence or the absence of hydrogen and/or comonomer in the polymerization process.

Abstract: The present invention discloses a process for preparing polyethylene resins in a double loop reactor wherein the catalyst system comprises a bis-tetrahydroindenyl and a bis-indenyl catalyst component deposited on the same support. It also discloses the polyethylene resins obtained by the process and their use to prepare films having a good compromise of haze, processing and mechanical properties.

Abstract: The invention relates to a continuous process for preparing polyolefins having a bimodal or multimodal molar mass distribution in suspension in at least two reactors R1, R2.x, R3.y which are connected in series and in which different reaction conditions are set. In this process, the offgases A1, A2.x, A3.y, A4 and A5 leaving all the reactors connected in series are firstly collected, the collected offgases are then compressed in a compression stage 10, the compressed offgases are subsequently cooled and the cooled material is separated into a gaseous fraction and a liquid fraction. The separated fractions are then recirculated to the polymerization process at different points. The process of the invention allows the total conversion of the polymerization, based on monomer and comonomer used, to be increased to a surprising extent.

Abstract: In the present invention, a tubular flow reactor can maintain a plug flow property even though the tubular flow reactor is downsized, and provided is the tubular flow reactor with which uniform resin fine particles exhibiting a narrow particle size distribution and a narrow molecular weight distribution can be prepared when the tubular flow reactor is used for preparation of the resin fine particle via emulsion polymerization or the like. Disclosed is a tubular flow reactor possessing a stirring blade and a cylindrical channel, wherein a ratio d/D is 0.3-0.9 when a diameter of the stirring blade is represented by d and an inner diameter of the cylindrical channel is represented by D, and a ratio Lb/La is 0.80-0.99 when a length of the stirring blade is represented by Lb and a length of the cylindrical channel is represented by La.

Abstract: A process for the polymerization of olefins carried out in a gas-phase reactor having interconnected polymerization zones, where the growing polymer particles flow upward through a first polymerization zone (riser) under fast fluidization or transport conditions, leave said riser and enter a second polymerization zone (downcomer) through which they flow downward under the action of gravity, leave said downcomer and are reintroduced into the riser, a gas recycle stream being withdrawn from said first polymerization zone, subjected to cooling below its dew point and then returned to said first polymerization zone, the process being characterized in that said gas recycle stream is cooled at a temperature Tc ranging from 0.05° C. to 3° C. below its dew point.

Abstract: Process for transferring a slurry stream containing polymer through a transfer line from a polymerisation reactor to a downstream vessel by, prior to entry into the downstream vessel, separating the slurry stream into two flows, the first flow being recycled upstream of the flow separation and the second flow being passed into the downstream vessel. The flow separation is located more than halfway along the transfer line between the reactor and the downstream vessel.

Abstract: A process for fluid phase in-line blending of polymers.

Abstract: The present invention relates to a loop reactor suitable for olefin polymerization process comprising: a plurality of interconnected pipes defining a flow path for a polymer slurry, said slurry consisting essentially of an olefin reactant, a polymerization catalyst, liquid diluent and solid olefin polymer particles, means for introducing olefin reactant, polymerization catalyst and diluent into said reactor, a pump suitable for maintaining the polymer slurry in circulation in said reactor, and single settling leg connected to said loop reactor through (a) a take off line extending from said reactor to said settling leg and configured to remove said polymer slurry from said reactor, and (b) a return line extending from said settling leg to said reactor, characterized in that said take off line is radially connected to said single settling leg.

Abstract: A continuous gas phase circulating bed reactor, including: a riser for contacting a catalyst and a first gas composition comprising an olefin to form a polyolefin under fast-fluidization regime or a dilute-phase pneumatic conveying regime conditions; a downer for contacting the catalyst and a second gas composition comprising an olefin to form additional polyolefin under fast fluidization regime or a dilute-phase pneumatic conveying regime conditions; and a transport section for conveying at least a portion of the catalyst, polyolefin, and additional polyolefin from the downer to the riser. Also disclosed is a polymerization process using such a circulating bed reactor.

Abstract: A method for the copolymerization of ethylene and a C3+ olefin copolymer in a loop reactor system and polymers formed therefrom are described herein.

Abstract: The pump assembly includes an impeller rotatably mounted in a pipe of the reactor having blades that generate a flow of fluid slurry through the pipe, a nosecone protruding in an upstream direction in front of the impeller blades that rotates along with the blades, and a plurality of stationary guide vanes connected to the housing upstream of the impeller blades and having free ends that are radially spaced apart from the nosecone. The leading edges of the stationary vanes are shaped to direct any stringy material into the radial gaps between the free ends of the stationary vanes and the rotating nose cone to be shredded and thus prevent fouling and clogging of the pump assembly when such stringy material is generated during the polymerization process.