US 4,308,369 AGranted

High efficiency catalyst for polymerizing olefins

AssigneeThe Dow Chemical Company

InventorsRandall S. Shipley, Donald F. Birkelbach, Kirby Lowery, Jr.

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Abstract

Olefins are polymerized in the presence of a catalyst prepared by reacting tetravalent titanium compounds such as a titanium tetraalkoxide, an anhydrous zinc compound such as diethyl zinc, an organomagnesium component such as a hydrocarbon soluble complex of dialkyl magnesium and an alkyl aluminum and a halide source such as a hydrogen halide or an alkyl aluminum halide and an aluminum compound if the halide source or organomagnesium component does not contain sufficient quantities of aluminum. Polymerization processes employing this catalyst composition do not require conventional catalyst removal steps in order to provide polymers having suitable color and other physical characteristics and these catalysts produce polymers having broader molecular weight distributions than do corresponding catalysts without the anhydrous zinc compound.

A process for the polymerization of one or more polymerizable .alpha.-olefins under conditions characteristic of Ziegler polymerization wherein the polymerization is conducted in the presence of, as a catalyst for said polymerization, a catalytic reaction product of

(A) a tetravalent titanium compound represented by the formula TiX.sub.n (OR).sub.4-n wherein X is a halogen, R is an alkyl or an aryl group having from 1 to 12 carbon atoms and n has a value of 0 to 4;
(B) an anhydrous divalent zinc compound represented by the formula R.sub.2 Zn wherein each R is independently a hydrocarbyl group having from 1 to about 20 carbon atoms;
(C) an organomagnesium component selected from (1) an organomagnesium compound or (2) a complex of an organomagnesium compound and an organometallic compound in an amount sufficient to solubilize the organomagnesium compound in a hydrocarbon solvent, said organomagnesium compound and said complex being represented respectively by the following formulas MgR".sub.2 and MgR".sub.2.xMR".sub.y wherein each R" is independently a hydrocarbyl group having from 1 to 20 carbon atoms;
M is a metal selected from Al, Zn, Si, Sn, B and P;
y is the number of hydrocarbyl groups and corresponds to the valency of M and x is about 0.001 to 10 and
(D) a halide source selected from (1) an active non-metallic halide, said non-metallic halide corresponding to the formula R'X wherein R' is hydrogen or a hydrocarbyl group such that the hydrocarbyl halide is at least as active as sec-butyl chloride and does not poison the catalyst and X is halogen or (2) a metallic halide corresponding to the formula MR.sub.y-a X.sub.a wherein M is a metal of Group IIIA or IVA of Mendeleev's Periodic Table of Elements, R is a monovalent hydrocarbyl radical, X is halogen, y is a number corresponding to the valence of M and a is a number of 1 to y;
provided that the proportions of the foregoing components of said catalytic reaction product being such that the atomic ratio of Zn:Mg is from about 0.02:1 to about 25:1, the atomic ratio of Zn:Al is from about 0.02:1 to about 50:1, the atomic ratio of Zn:Ti is from about 0.1:1 to about 200:1, the atomic ratio of excess X:Al is from about 0.0005:1 to about 10:1;
and further provided that when the organomagnesium component and/or the halide source provides insufficient quantities of aluminum, there is also present an aluminum compound represented by the formula AlR.sub.y' X.sub.y" wherein R and X are as defined above and y' and y" each have a value of from zero to three with the sum of y' and y" being three;
and wherein the catalyst components are added in the order selected from
(a) (C), (D), (B), aluminum compound, if required, and (A);
(b) (C), (D), (A), aluminum compound, if required, and (B) and provided that the halide source, (D), is other than a tin compound;
and
(c) (C), (D), aluminum compound, if required, (A), and (B).

10 more elements

Abstract

Claims24