Catalyst composition and system having extended lifetime
A Ziegler-Natta catalyst composition is disclosed. The catalyst composition includes an internal electron donor with improved polymerization kinetics, a long lifetime, improved stereoselectivity and/or improved hydrogen response.
1. A catalyst composition for stereoselective polymerization of propylene comprising:
a combination of a magnesium moiety, a titanium moiety, and an internal electron donor, the internal electron donor comprising:
wherein:
R 1 and R 4 are each a hydrocarbyl group having from 1 to 20 carbon atoms;
R 2 is hydrogen;
R 3 is a substituted or unsubstituted hydrocarbyl group having from 5 to 15 carbon atoms, the hydrocarbyl group having a branched or linear structure or comprising a cycloalkyl group having from 7 to 15 carbon atoms;
E 1 and E 2 are the same or different and selected from the group consisting of an alkyl having 1 to 20 carbon atoms, a substituted alkyl having 1 to 20 carbon atoms, an aryl having 6 to 20 carbon atoms, a substituted aryl having 6 to 20 carbon atoms, and an inert functional group having 1 to 20 carbon atoms and optionally containing heteroatoms;
X 1 is NR 5 and X 2 is O, S, or NR 5 , or X 2 is NR 5 and X 1 is O, S, or NR 5 ; and
R 5 is a hydrocarbyl group having 1 to 20 carbon atoms or is hydrogen.
2. The catalyst composition of claim 1 , wherein R 3 is a branched alkyl or alkenyl group.
3. The catalyst composition of claim 2 , wherein the branched alkyl or alkenyl group contains from 5 to 10 carbon atoms.
4. The catalyst composition of claim 1 , wherein R 3 is a 3-pentyl group, a 2-pentyl group, a cycloheptyl group, or a cyclooctyl group.
5. The catalyst composition of claim 1 , wherein R 1 and R 4 are the same.
6. The catalyst composition of claim 1 , wherein R 1 and R 4 are linear hydrocarbyl groups.
7. The catalyst composition of claim 1 , wherein R 1 and R 4 comprise a C1 to C8 alkyl group, a C2 to C8 alkenyl group, or mixtures thereof.
8. The catalyst composition of claim 1 , wherein the magnesium moiety comprises a magnesium halide.
9. The catalyst composition of claim 1 , wherein E 1 and E 2 both comprise phenyl groups.
10. The catalyst composition of claim 1 , further comprising a cocatalyst, optionally an activity limiting agent and optionally a selectivity control agent.
11. The catalyst composition of claim 10 , wherein the cocatalyst comprises a hydrocarbon aluminum cocatalyst.
12. The catalyst composition of claim 10 , wherein the selectivity control agent is present and comprises an alkoxysilane.
13. The catalyst composition of claim 10 , wherein the selectivity control agent comprises dicyclopentyldimethoxysilane, di-tert-butyldimethoxysilane, methylcyclohexyldimethoxysilane, methylcyclohexyldiethoxysilane, ethylcyclohexyldimethoxysilane, diphenyldimethoxysilane, diisopropyldimethoxysilane, di-n-propyldimethoxysilane, diisobutyldimethoxysilane, diisobutyldiethoxysilane, isobutylisopropyldimethoxysilane, di-n-butyldimethoxysilane, cyclopentyltrimethoxysilane, isopropyltrimethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, ethyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, diethylaminotriethoxysilane, cyclopentylpyrrolidinodimethoxysilane, bis(pyrrolidino)dimethoxysilane, bis(perhydroisoquinolino)dimethoxysilane, dimethyldimethoxysilane or mixtures thereof.
14. The catalyst composition of claim 1 , wherein the magnesium moiety comprises a spray crystallized magnesium halide compound comprising ethanol and magnesium chloride in a weight ratio of from about 1.5:1 to about 3.1:1.
15. A polymerization process comprising: polymerizing an olefin in the presence of a catalyst composition comprising the catalyst composition of claim 1 .
16. The polymerization process of claim 15 , wherein the olefin comprises propylene for forming a propylene homopolymer or comprises propylene and ethylene for forming a propylene and ethylene copolymer.
17. The polymerization process of claim 16 , wherein the process produces a heterophasic polymer.
18. The polymerization process of claim 17 , wherein the heterophasic polymer comprises a first polymer phase comprising a polypropylene homopolymer or a polypropylene random copolymer, the heterophasic polymer further comprising a second polymer phase combined with the first polymer phase, the second polymer phase comprising an elastomeric propylene ethylene copolymer.
19. The polymerization process of claim 18 , wherein the first polymer phase is formed in a first reactor and the second polymer phase is formed in a second reactor, the catalyst composition remaining active in both the first reactor and the second reactor.
20. An olefin polymer containing the catalyst composition of claim 1 .
21. The catalyst composition of claim 11 , wherein the hydrocarbon aluminum cocatalyst comprises triethylaluminum.