High activity ziegler-natta catalyst for high molecular weight polyolefins
AssigneeNOVA Chemicals (International) S.A.
InventorsJesus Vela Estrada, Vaclav George Zboril
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Abstract
By controlling the hold up times, concentrations and temperatures for mixing the components of aluminum, titanium and magnesium based catalyst for solution polymerization it is possible to prepare a catalyst having a high activity, which prepares high molecular weight polyolefins. Generally, a catalyst loses activity and produces lower molecular weight polymer at higher temperatures. The catalyst of the present invention permits comparable polymers to be produced with higher catalyst activity and at higher reaction temperatures by increasing the concentration of the components used during the preparation of the catalyst.
Claims20
A process for preparing an olefin polymerization catalyst comprising sequentially mixing:
- (i) a mixture of a compound of the formula (R1)2Mg where in R1 is selected from the group consisting of C1-6 alkyl radicals and a compound of the formula Al1(R2)3 wherein R2 is selected from the group consisting of C1-6 alkyl radicals;
- and HCl or a reactive organic chloride of the formula R3Cl wherein R3 is selected from the group consisting of C1-6 alkyl radicals and C6-12 aromatic radicals;
- and maintaining the resulting mixture at a temperature from 40° C. to 60° C. for a period from 60 to 150 seconds at a concentration of R3Cl from 5 to 100 mmol/L;
- then
- (ii) adding a titanium compound of the formula (R4)aTiClb−a wherein R4 is a C1-6 alkoxy radical and a and b are integers from 0 to 4 and the sum of a+b is 4 to provide a molar ratio of Mg:Al1 from 3:1 to 8:1;
- a molar ratio of Cl:Mg from 1.5:1 to 2.5:1;
- a molar ratio of Al1:Ti from 0.5:1 to 1.5:1;
- and a molar ratio of Mg:Ti from 3:1 to 8:1;
- and holding the resulting mixture for a time from 20 to 90 seconds at a temperature from 40° C. to 60° C. at a concentration of (R4)aTiClb−a from 0.1 to 10 mmol/L;
- and
- (iii) adding a compound of the formula (R5)2Al2(R6) wherein R5 is a C1-6 alkyl radical and R6 is a C1-6 alkoxy radical and holding the resulting mixture at a temperature from temperature from 40° C. to 60° C. for a period of time from 5 to 30 seconds.
Dependencies are inferred from the claim text.