Dow Global Technolgoies LLC

The Dow Chemical Company

Werner Zschoch

Otto J Berbee

Cornelis J Hosman

Mehmet Demirors

Jian Jim Wang

Teresa Plumley Karjala

Sarat Munjal

Lonnie G Hazlitt

Stefan Hinrichs

Christopher R Eddy

Wallace W Yau

Juan Manuel Mezquita

Gerd Lohse

Gerrit Hommersom

Harald Beer

Larry A Morse

John T Keating

Larry Morse

John Keating

Wallace Yau

Otto Berbee

The invention provides a high pressure polymerization process to form an ethylene-based polymer, the process comprising at least the following steps: feeding ethylene to a first reaction zone and to one or more subsequent reaction zones, and wherein for each subsequent reaction zone that receives fresh ethylene, the ratio, Rn (n=reaction zone number, n&#x3e;1), of 'mass fraction of fresh ethylene fed to the first reaction zone (RZ1)' to 'mass fraction of fresh ethylene fed to the nth reaction zone (RZn)' is (Rn=RZ1/RZn) greater than 1, or is from 0 to 0.30, and wherein the &#x201c;total amount of ethylene fed to the polymerization process&#x201d; derives from at least one fresh ethylene stream and at least one recycled ethylene stream, and wherein the at least one recycled ethylene stream comprises at least one chain transfer agent and/or comprises at greater than, or equal to, 1 weight %, based on total amount of components in recycled ethylene stream, of one or more non-ethylene components and/or CTA(s); and wherein the inlet feed to each reaction zone comprises less than 5 weight ppm oxygen based on the total weight of mass flows fed to the reaction zone. The invention also provides a high pressure polymerization process to form an ethylene-based polymer, the process comprising at least the following steps: feeding ethylene to a first reaction zone and to one or more subsequent reaction zones, and wherein 100 weight percent of the total amount of fresh ethylene fed to the polymerization process is fed to the first reaction zone, and wherein the &#x201c;total amount of ethylene fed to the polymerization process&#x201d; derives from at least one fresh ethylene stream and at least one recycled ethylene stream, and wherein the at least one recycled ethylene stream comprises at least one chain transfer agent and/or comprises at greater than, or equal to, 1 weight %, based on total amount of components in recycled ethylene stream, of one or more non-ethylene components and/or CTA(s); and wherein the inlet stream to each reaction zone comprises less than, or equal to, 5 weight ppm oxygen, based on the total weight of mass flows fed to the reaction zone.

Polymerization processes with fresh ethylene distributions for preparation of low density ethylene-based polymers

Disclosed is an ethylene-based polymer with a density from about 0.90 to about 0.94 in grams per cubic centimeter, with a molecular weight distribution (M/M) from about 2 to about 30, a melt index (I) from about 0.1 to about 50 grams per 10 minutes, and further comprising sulfur from about 5 to about 4000 parts per million. The amount of sulfur is also determined based upon the total weight of the ethylene-based polymer. Also disclosed is process for making an ethylene-based polymer which includes the steps of splitting a process fluid for delivery into a tubular reactor; feeding an upstream process feed stream into a first reaction zone and at least one downstream process feed stream into at least one other reaction zone, where the process fluid has an average velocity of at least 10 meters per second; and initiating a free-radical polymerization reaction.

High pressure low density polyethylene resins with improved optical properties produced through use of highly active chain transfer agents

The present invention provides an injection nozzle for mixing an initiator with a process fluid. Then injection nozzle comprises a body comprising an inlet port, and outlet port, and an injector inlet; a process fluid flow passage; an initiator flow fluid passage; and a stylus. The process fluid flow passage comprises a constricting portion and an expanding portion to help improve transport and mixing. The injection nozzle is useful for injecting a fluid into another fluid at elevated temperatures and pressures, and for maximizing mixing of the fluids.

LDPE tubular reactor peroxide mixer

The invention pertains to a method for producing ethylene homopolymerizates and ethylene copolymerizates exhibiting a lower mass density of up to 0.930 g/cm and a melt index ranging from 0.15 to 25 g/10 min (2.16 kg; 463 K). Said polymerizates exhibit an improved processing stability and improved availability in the installation at pressures greater than 1000 bar and at temperatures of up to 603 K. The polymerizates are produced in tubular reactors in the presence of radical-forming initiators, oxygen thereunder and chain transfer agents, of which at least one comprises an aldehydic structure. According to the inventive method, chemokinetic characteristics of the reactive feed materials (thermal half-life periods, concentrations, dosing quantities) are coupled with fluidically relevant characteristics of the tubular reactor (flow rate) while taking the target product quality (melt index, flow figure) into consideration. This coupling is carried out such that the interfering secondary reactions, especially polar-inductive substitution effects, which can lead to the formation and the enrichment of organic hydroperoxides are reduced to a minimum and, as a result, extraordinarily stable processing conditions can be obtained.

Method for producing ethylene homopolymerizates and ethylene copolymerizates of a lower mass density

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Naumburg, Germany

Werner Zschoch