Patent ID: 6849699
Filing Date: 2005-02-01
Classification: C08F

Abstract:
1. A continuous vapor-phase fluid-bed process for the preparation of ethylene homopolymers and copolymers having a density d of from 0.87 to 0.97 g/cm 3 in which ethylene or mixtures of ethylene and C 3 -C 8 α-monoolefins are (co)polymerized in the presence of a supported chromium catalyst wherein the support is a porous metal oxide or SiO 2 in the polymerization zone of a vapor-phase fluidized-bed reactor under pressures ranging from 1 to 100 bar and at temperatures ranging from 30° to 125° C. in the vapor phase in an agitated bed of bulk material comprising particulate polymer, the resultant heat of polymerization is removed by cooling the recirculated reactor gas and the resulting (co)polymer is removed from the vapor-phase fluidized-bed reactor, wherein, for the preparation of a (co)polymer of a specified density d, (co)polymerization is carried out at a temperature which is in a range restricted by an upper envelope defined by equation I and a lower envelope defined by equation II in which the variables have the following meanings: T T d′ is the numerical value of the density d of the (co)polymer to be synthesized.