Dual reactor ethylene polymerization process
AssigneeNova Chemical (International) S.A.
InventorsIsam Jaber, Stephen John Brown
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Abstract
A dual reactor process for the solution and (co)polymerization of ethylene uses two different types of catalysts in the two reactors. A catalyst having a phosphinimine ligand is used in the first reactor. A Ziegler Natta catalyst is used in the second reactor. The process of this invention is comparatively easy to control and may be used to produce polyethylene products having a broad molecular weight distribution. Linear low density produced according to this invention is well suited for the manufacture of molded goods and plastic films.
Claims7
A medium pressure solution polymerization process comprising:
- A) polymerizing ethylene, optionally with one or more C3-12 alpha olefins, in solvent in a first polymerization reactor at a temperature of from 80 to 200° C. and a pressure of from 500 to 8,000 psi in the presence of (a) a first catalyst which is an organometallic complex of a group 4 or 5 metal that is characterized by having at least one phosphinimine ligand;
- and (b) a first cocatalyst;
- and
- B) passing said first polymer solution into a second polymerization reactor and polymerizing ethylene, optionally with one or more C3-12 alpha olefins, in said second stirred polymerization reactor at a higher polymerization temperature than that of said first reactor in the presence of a Ziegler Natta catalyst, wherein said Ziegler Natta catalyst comprises, 1) a transition metal compound of a transition metal selected from the group consisting of groups 3, 4 or 5 transition metals and, 2) an organoaluminum component which is defined by the formula:
- Al(X′)a(OR)b(R)c
- wherein:
- X′ is a halide;
- OR is an alkoxy or aryloxy group;
- R is a hydrocarbyl;
- and a, b, or c are each 0, 1, 2 or 3 with the provisos that a+b+c=3 and b+c≧1.
Dependencies are inferred from the claim text.