Continuous production of (co)polyethylene by high-pressure polymerization uses free radical initiator as solution in isoparaffin of given boiling range, which is separated in low pressure cycle and re-used for dissolving initiator

摘要

In continuous production of (co)polyethylene (I) using free radical polymerization initiator (II) and optionally molecular weight regulator at 100-4000 bar and 120-350[deg]C, in which (I) is separated from unpolymerized ethylene (III) (and comonomers) in high-pressure and low-pressure (LP) stages, (II) is dissolved in isoparaffin (V) with boiling point up to 160[deg]C and (V) is separated from other constituents in LP cycle and re-used for dissolving (II). In continuous production of (co)polyethylene (I) in the presence of free radical polymerization initiator (II) and optionally molecular weight regulator at 100-4000 bar and 120-350[deg]C, in which (I) is separated from unpolymerized ethylene (III) and optionally comonomers (IV) in a high-pressure stage (4a) at 100-500 bar and low-pressure stage(s) (4b) at 1-100 bar, (III) separated in high-pressure stage (4a) is circulated in the high-pressure cycle (9) and (III) separated in the low-pressure stage (4b) is separated from (IV), oligomers and/or polymers in a low-pressure cycle (10) and returned to the inlet of the tubular reactor, the novel features are that (II) is dissolved in an isoparaffinic solvent (V) with a boiling point of at most 160[deg]C and (V) is separated from the other constituents in the low-pressure cycle (10) and re-used for dissolving (II). An independent claim is also included for the equipment used.