Catalyst composition with mixed selectivity control agent and method
The present disclosure provides a Ziegler-Natta catalyst composition comprising a procatalyst, a cocatalyst and a mixed external electron donor comprising a first selectivity control agent, a second selectivity control agent, and an activity limiting agent. A polymerization process incorporating the present catalyst composition produces a high-stiffness propylene-based polymer with a melt flow rate greater than about 50 g/10 min. The polymerization process occurs in a single reactor, utilizing standard hydrogen concentration with no visbreaking.
1. A catalyst composition comprising:
a procatalyst composition comprising a phenylene dibenzoate comprising:
wherein R 1 -R 14 are the same or different; each of R 1 -R 14 is selected from hydrogen, a substituted hydrocarbyl group having 1 to 20 carbon atoms, an unsubstituted hydrocarbyl group having 1 to 20 carbon atoms, a halogen, or combinations thereof; and at least one of R 1 -R 14 is not hydrogen;
a cocatalyst; and
a mixed external electron donor (M-EED) comprising an activity limiting agent (ALA), a first selectivity control agent (SCA1), a second selectivity control agent (SCA2) different from SCA1, wherein the SCA1:SCA2 mole ratio is less than or equal to 1.0, the total SCA:ALA mole ratio is 0.43-2.33:1, and the SCA1 to total SCA mole ratio is 0.2-0.5:1.
2. The catalyst composition of claim 1 wherein the SCA1 comprises a member selected from the group consisting of a dimethoxysilane, a dimethoxysilane having at least one secondary alkyl group, a dimethoxysilane having a secondary amino group directly bonded to the silicon atom, and combinations thereof.
3. The catalyst composition of claim 1 wherein SCA2 is selected from the group consisting of 1-ethoxy-2-n-pentoxybenzene and 1-ethoxy-2-(6-(2-ethoxyphenoxy)hexyloxy)benzene.
4. The catalyst composition of claim 1 wherein the ALA is selected from the group consisting of an aromatic ester or a derivative thereof, an aliphatic ester or a derivative thereof, a diether, a poly(alkylene glycol) ester, and combinations thereof.
5. The catalyst composition of claim 1 comprising an aluminum-containing cocatalyst and a mole ratio of Al to M-EED less than about 6.0.
6. The catalyst composition of claim 1 wherein the total SCA:ALA mole ratio is 0.43-1.0:1.
7. The catalyst composition of claim 1 wherein the catalyst composition is a self-limiting catalyst composition.
8. The catalyst composition of claim 1 wherein SCA1 comprises dicyclopentyldimethoxysilane.
9. The catalyst composition of claim 1 wherein SCA2 is selected from the group consisting of methylcyclohexyldiethoxysilane, di-isobutyldiethoxysilane, n-propyltriethoxysilane, tetraethoxysilane, di-n-butyl-dimethoxysilane, benzyltriethoxysilane, but-3-enyltriethoxysilane, 1-(triethoxysilyl)-2-pentene, (triethoxysilyl)cyclohexane, and combinations thereof.
10. The catalyst composition of claim 1 wherein the ALA comprises isopropyl myristate.
11. The catalyst composition of claim 1 wherein the SCA1 is a dimethoxysilane.
12. The catalyst composition of claim 1 wherein the SCA2 is a triethoxysilane.
13. The catalyst composition of claim 1 wherein the ALA is a C 4 -C 30 aliphatic acid ester.
14. The catalyst composition of claim 1 wherein the ALA is isopropyl myristate.
15. The catalyst composition of claim 1 wherein the phenylene dibenzoate is 3-methyl-5-tert-butyl-1,2-phenylene dibenzoate.
16. The catalyst composition of claim 1 wherein the phenylene dibenzoate is 3-methyl-5-tertbutyl-1,2-phenylene dibenzoate, the SCA1 is dicyclopentyldimethoxysilane, the SCA2 is a triethoxysilane and the ALA is isopropylmyristate.
17. A catalyst composition comprising:
(i) a procatalyst comprising a phenylene dibenzoate comprising:
wherein at least one of R 1 -R 4 is selected from an unsubstituted hydrocarbyl group having 2 to 20 carbon atoms or a substituted hydrocarbyl group having 2 to 20 carbon atoms; each of the other R groups of R 1 -R 4 is hydrogen; and each of R 5 -R 14 is selected from hydrogen, an unsubstituted hydrocarbyl group having 1 to 20 carbon atoms, a substituted hydrocarbyl group having 1 to 20 atoms, a halogen, or combinations thereof;
(ii) a cocatalyst; and
(iii) a mixed external electron donor (M-EED) comprising a first selectivity control agent (SCA1), a second selectivity control agent (SCA2) different from SCA1, and an activity limiting agent (ALA), wherein the SCA1:SCA2 mole ratio is less than or equal to 1.0, the total SCA:ALA mole ratio is 0.43-2.33:1, and the SCA1 to total SCA mole ratio is 0.2-0.5:1.
18. The catalyst composition of claim 17 wherein the catalyst composition includes Al, and the mole ratio of Al to total SCA1, SCA2 and ALA is in a range of 0.5-25:1.
19. The catalyst composition of claim 17 wherein SCA1 comprises a dimethoxysilane compound and SCA2 comprises a diethoxysilane compound.