| 摘要 |
1. A process for the continuous production of copolymers of ethylene with at least one alpha-monoolefin of 3 to 12 carbon atoms, as comonomer, by polymerizing a mixture of 100 molar parts of ethylene and 3 to 50 molar parts of the comonomer, using a transition metal catalyst system, at a temperature of from 50 to 110 degrees C and a pressure of 5 to 50 bars, in a stirred bed of particulate copolymer, a) the heat of polymerization being removed by Joule-Thomson cooling by flashing an excess of a monomer mixture, which has been compressed to a pressure that is 50 to 95 bars higher than the polymerization pressure, and is at a temperature that is 40 to 130 degrees C lower than the polymerization temperature, into the polymerization zone in such a way that the desired polymerization temperature therein is maintained by the resulting Joule-Thomson cold, and b) the amount of monomer mixture not consumed in the polymerization, which is gaseous, being removed from the polymerization zone and - while adding fresh monomer to make up for the amount of monomer consumed in the polymerization - recycled to the polymerization zone for flashing after it has been brought by compression and cooling to the pressure and temperature selected, prior to flashing, for Joule-Thomson cooling, wherein step (b) is so conducted that b1 ) the amount of gaseous monomer mixture (I) withdrawn from the polymerization zone and not consumed in the polymerization, which has been supplemented by fresh monomer, is cooled, prior to renewed compression, to such an extend that there is formed, in addition to a gaseous portion (II) of the monomer mixture, a liquid portion (III) which contains 50 to 80 mole % of the comonomer in the monomer mixture (I), b2 ) the two portions (II) and (III) of the monomer mixture, formed in step (b1 ), are separately brought by compression and cooling to the pressure and temperature selected, prior to flashing, for Joule-Thomson cooling, and then recycled to the polymerization zone.
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