Multistage process for producing ethylene polymer compositions

摘要

The present invention relates to a process of producing an ethylene polymer composition in multiple stages, of which the first stage is preferably a slurry polymerization stage, in the presence of a catalyst system, comprising: a) a solid catalyst precursor, comprising a transition metal selected from titanium and vanadium; magnesium; a halide, optionally an electron donor; and a solid particulate material comprising an inorganic oxide, and wherein the median particle diameter, D50, of the solid catalyst precursor, based upon the total volume of solid catalyst precursor, is from 1 to 13 micrometers; and b) an organoaluminium compound.

主权项

1. A composition comprising:
a solid comprising a mixture of first and second ethylene polymers, from 0.1 to 10 parts by weight of a stabilizing agent for each 100 parts by weight of the mixture, and a plurality of gels of varying size dispersed in the solid, wherein said composition has a density of 0.950-0.970 g/cm3, an MI5 of 0.08 to 1.0 g/10 min, a 3-point flexural Young's modulus when compression molded, as measured on an Instron apparatus according to ISO 178, greater than
1.340*{1-exp[-235*(density−0.9451)]}; and wherein a 5 m2 sample of a 50 micrometer thick cast film prepared from a sample of the composition exhibits both of: (i) less than 6 gels per m2 of a size greater than 800 micrometers, and (ii) less than 100 gels per m2 of a size in the range from 400 to 800 micrometers.