Patent ID: 7737229
Filing Date: 2010-06-15
Classification: C08F

Abstract:
1. A process for continuously preparing an ethylene homopolymer or copolymer in a high-pressure tube reactor in presence of at least one free-radical polymerization initiator and, optionally, a least one molecular weight regulator at from 120° C. to 350° C. and a pressure from 1000 to 4000 bar, wherein the ethylene homopolymer or copolymer is separated from unpolymerized ethylene and optionally from comonomers in a high-pressure stage at a pressure from 100 to 500 bar and at least one low-pressure stage at a pressure from 1 to 100 bar, the unpolymerized ethylene separated off in the high-pressure stage is separated from any remaining monomeric, oligomeric and/or polymeric constituents and is re-circulated to a first inlet of the tube reactor in a high-pressure circuit, and the unpolymerized ethylene separated off in the low-pressure stage is separated from any remaining monomeric, oligomeric and/or polymeric constituents and is re-circulated to a second inlet of the tube reactor in a low-pressure circuit, wherein the free-radical polymerization initiator is used as a solution in an isoparaffinic solvent, the isoparaffinic solvent comprising a boiling point equal to or less than 160° C., and the isoparaffinic solvent is separated from the monomeric, oligomeric and/or polymeric constituents in the low-pressure circuit, and the isoparaffinic solvent is reused for dissolving the free-radical polymerization initiator.