Patent ID: 6025448
Filing Date: 2000-02-15
Classification: C08F,C08L,Y10S

Abstract:
A fluidized bed, gas phase process for the production of an ethylene polymer having long chain branching and a critical shear stress at the onset of gross melt fracture of greater than about 4.times.10.sup.6 dyne/cm.sup.2, the process comprising the steps of:(A) feeding gaseous monomers into a fluidized bed reactor and contacting the monomers under continuous polymerization conditions in the reactor, the gaseous monomers comprising at least one of (i) ethylene, or (ii) ethylene and at least one of a copolymerizable alpha-olefin or diolefin, in the presence of a catalyst prepared from:1. a metal complex corresponding to the formula: ##STR5## wherein: M is a Group 4 metal in the +2, +3 or +4 formal oxidation state;L is a group containing a cyclic, delocalized, aromatic, anionic, system through which the L group is bound to M, and which L group is also bound to Z, said L group containing up to 60 nonhydrogen atoms;Z is a moiety covalently bound to both L and Y, comprising boron, or a member of Group 14 of the Periodic Table of the Elements, said moiety having up to 60 non-hydrogen atoms;Y is a moiety comprising nitrogen, phosphorus, sulfur or oxygen through which Y is covalently bound to both Z and M, said moiety having up to 25 nonhydrogen atoms;X' independently each occurrence is a Lewis base containing up to 40 nonhydrogen atoms;X independently each occurrence is a monovalent anionic moiety having up to 20 nonhydrogen atoms, provided however that neither X is an aromatic group that is .pi.-bonded to M, optionally, two X groups may be covalently bound together forming a divalent dianionic moiety having both valences bound to M, or further optionally one or more X and one X' group may be bonded together thereby forming a moiety that is both covalently bound to M and coordinated thereto by means of Lewis base functionality;q is a number from 0 to 1; andn is 0, 1 or 2 depending on the formal oxidation state of M;2. an activating cocatalyst selected from the group consisting of neutral Lewis acids and nonpolymeric, compatible noncoordinating ion forming compounds; and3. a support;(B) withdrawing continuously from the reactor unreacted gaseous monomers, and forming from the withdrawn unreacted gaseous monomers a recycle stream;(C) introducing a condensable fluid into the recycle stream to increase the dew point of the recycle stream and produce a two-phase mixture, and feeding the recycle stream to the reactor;(D) producing in the reactor from the gaseous monomers an ethylene polymer having long chain branching; and(E) recovering the ethylene polymer having long chain branching from the reactor.