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

• Main Authors: HOSMAN CORNELIS J, BERBEE OTTO J, ZSCHOCH WERNER
• Format: Patent
• Language: English
• Published: 01.09.2015
• Subjects: CHEMISTRY; COMPOSITIONS BASED THEREON; MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVINGCARBON-TO-CARBON UNSATURATED BONDS; METALLURGY; ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP

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>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 "total amount of ethylene fed to the polymerization process" 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 "total amount of ethylene fed to the polymerization process" 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.