Catalyst composition with mixed selectivity control agent and method
View Patent ↗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 polymerization process comprising:
contacting propylene and optionally at least one other olefin with a catalyst composition in a polymerization reactor under polymerization conditions, the catalyst composition comprising (i) a procatalyst 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;
(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;
controlling the mole ratio of (1) SCA1 to SCA2, and/or (2) total-SCA to ALA, and/or (3) SCA1 to total SCA; and
forming a propylene-based polymer having a melt flow rate of at least 50 g/10 min as measured in accordance with ASTM D 1238-01 at 230° C. with a 2.16 kg weight.
2. The process of claim 1 comprising self-limiting the polymerization when the temperature in the polymerization reactor is greater than about 100° C.
3. The process of claim 1 comprising forming a propylene-based polymer comprising at least about 5 ppm ALA.
4. The process of claim 1 comprising forming an uncracked propylene-based polymer.
5. The process of claim 1 wherein the SCA1 is a dimethoxysilane.
6. The process of claim 1 wherein the SCA1 is dicyclopentyldimethoxysilane.
7. The process of claim 1 wherein the SCA2 is a triethoxysilane.
8. The process of claim 1 wherein the ALA is a C 4 -C 30 aliphatic acid ester.
9. The process of claim 1 wherein the ALA is isopropyl myristate.
10. The process of claim 1 wherein the phenylene dibenzoate is 3-methyl-5-tert-butyl-1,2-phenylene dibenzoate.
11. The process of claim 1 comprising forming a propylene-based polymer having a melt flow rate of greater than 60 g/10 min as measured in accordance with ASTM D 1238-01 at 230° C. with a 2.16 kg weight.
12. The process of claim 1 comprising forming a propylene-based polymer having a melt flow rate of greater than 70 g/10 min as measured in accordance with ASTM D 1238-01 at 230° C. with a 2.16 kg weight.
13. The process of claim 1 comprising forming a propylene-based polymer having a melt flow rate of greater than 100 g/10 min as measured in accordance with ASTM D 1238-01 at 230° C. with a 2.16 kg weight.
14. The process of claim 1 comprising forming a propylene-based polymer having a xylene solubles content of less than 3%.
15. The process of claim 1 wherein the phenylene dibenzoate is 3-methyl-5-tert-butyl-1,2-phenylene dibenzoate, the SCA1 is dicyclopentyldimethoxysilane, the SCA2 is a triethoxysilane and the ALA is isopropylmyristate.
16. The process of claim 1 , forming the propylene-based polymer to include at least 5 ppm ALA.
17. The process of claim 1 , wherein the catalyst composition includes Al, and the process further comprises controlling a mole ratio of Al to total SCA1, SCA2 and ALA in the range of 0.5-25:1.
18. The process of claim 1 , wherein SCA1 comprises a dimethoxysilane compound and SCA2 comprises a diethoxysilane compound.
19. A polymerization process comprising:
contacting propylene and optionally at least one other olefin with a catalyst composition in a polymerization reactor under polymerization conditions, the 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 and 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, and 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;
controlling the mole ratio of (1) SCA1 to SCA2, and/or (2) total-SCA to ALA, and/or (3) SCA1 to total SCA; and
forming a propylene-based polymer having a melt flow rate of at least 50 g/10 min as measured in accordance with ASTM D 1238-01 at 230° C. with a 2.16 kg weight.
20. The process of claim 19 , forming the propylene-based polymer to include at least 5 ppm ALA.
21. The process of claim 19 , wherein the catalyst composition includes Al, and the process further comprises controlling a mole ratio of Al to total SCA1, SCA2 and ALA in the range of 0.5-25:1.
22. The process of claim 19 , wherein SCA1 comprises a dimethoxysilane compound and SCA2 comprises a diethoxysilane compound.