Patent ID: 6545088
Filing Date: 2003-04-08
Classification: C08F,C08L

Abstract:
A process for the manufacture of an ethylene/&agr;-olefin/diene monomer elastomer having a density of from about 0.850 g/cm3 to about 0.895 g/cm3, the process comprising the steps of:A. contacting in a first reactor (1) ethylene, (2) at least one C3-C20 aliphatic &agr;-olefin, (3) at least one C4-C20 diene, (4) an activated catalyst comprising a Group 4 metal metallocene complex, and (5) a solvent, the first reactor operated such that a first elastomeric product is produced at a polymer concentration of from about 1 to about 15 weight percent, based on the weight of the reaction mass in the first reactor; B. contacting in a second reactor (1) ethylene, (2) at least one C3-C10 aliphatic &agr;-olefin, (3) at least one C4-C20 diene, (4) an activated catalyst comprising a Group 4 metal metallocene complex, (5) a solvent, and (6) a product stream from the first reactor, the second reactor operated such that a second elastomeric product is produced at a polymer concentration of from about 2 to about 30 weight percent, based on the weight of the reaction mass in the second reactor; C. removing an elastomeric product stream from the second reactor; D. removing solvent from the elastomeric product stream of the second reactor in an anhydrous, first stage solvent recovery operation such that the polymer concentration of the elastomeric product stream is increased by at least about 100 percent; and E. removing additional solvent in an anhydrous, second stage solvent recovery operation from the elastomeric product of the first stage solvent recovery operation such that the polymer concentration of the elastomeric product stream is in excess of 65 weight percent; the metallocene complex of steps A and B corresponding to the formula:ZLMXpXâ€²q in whichM is a metal of Group 4 of the Periodic Table of the Elements having an oxidation state of +2, +3 or +4 bound in an &eegr;5 bonding mode to L; L is a cyclopentadienyl-, indenyl-, tetrahydroindenyl-. fluorenyl-, tetrahydrofluorenyl-, or octahydrofluorenyl-group covalently substituted with at least a divalent moiety, Z, and L further may be substituted with from 1 to 8 substituents independently selected from the group consisting of hydrocarbyl, halo, halohydrocarbyl, hydrocarbyloxy, dihydrocarbylamine, dihydrocarbylphosphino or silyl groups, the substituent containing up to 20 nonhydrogen atoms; Z is a divalent moiety bound to both L and M via &sgr;-bonds, said Z comprising boron, or a member of Group 14 of the Periodic Table of the Elements, and optionally, also comprising nitrogen, phosphorus, sulfur or oxygen; X is an anionic or dianionic ligand group having up to 60 atoms exclusive of the class of ligands that are cyclic, delocalized, &pgr;-bound ligand groups: Xâ€² independently each occurrence is a neutral Lewis base ligating compound having up to 20 atoms; p is 0, 1 or 2, and is two less than the formal oxidation state of M, with the proviso that when X is a dianionic ligand group, p is 1; and q is 0, 1 or 2.