Catalyst Composition with Mixed Selectivity Control Agent and Method

• US 20090203863A1
• Filed: 02/23/2009
• Published: 08/13/2009
• Est. Priority Date: 08/24/2007
• Status: Active Grant

• Current Assignee: W R Grace & Company - CONN (WR Grace & Company)
• Original Assignee: Dow Global Technologies LLC (Dow, Inc.)
• Inventors: Chen, Linfeng
• Granted Patent: US 7,893,003 B2
• Time in Patent Office: Days
• US Class Current: 526/194
• CPC Class Codes: B01J 31/0201 Oxygen-containing compounds
• CPC Class Codes: B01J 31/0212 Alkoxylates
• CPC Class Codes: B01J 31/0272 containing elements other than those covered by B01J31/0201 - B01J31/0255
• CPC Class Codes: B01J 31/128 Mixtures of organometallic compounds
• CPC Class Codes: B01J 31/143 of aluminium
• CPC Class Codes: B01J 31/2213 At least two complexing oxygen atoms present in an at least bidentate or bridging ligand
• CPC Class Codes: B01J 31/2226 Anionic ligands, i.e. the overall ligand carries at least one formal negative charge
• CPC Class Codes: B01J 8/1809 Controlling processes
• CPC Class Codes: B01J 8/1872 Details of the fluidised bed reactor B01J8/1836 takes precedence
• CPC Class Codes: C08F 10/02 Ethene
• CPC Class Codes: C08F 10/06 Propene
• CPC Class Codes: C08F 110/06 Propene
• CPC Class Codes: C08F 2/00 Processes of polymerisation
• CPC Class Codes: C08F 2/34 Polymerisation in gaseous state
• CPC Class Codes: C08F 2/40 using retarding agents
• CPC Class Codes: C08F 210/06 Propene
• CPC Class Codes: C08F 210/16 Copolymers of ethene with alpha-alkenes, e.g. EP rubbers
• CPC Class Codes: C08F 2400/02 Control or adjustment of polymerization parameters
• CPC Class Codes: C08F 2500/12 Melt flow index or melt flow ratio
• CPC Class Codes: C08F 2500/18 Bulk density
• CPC Class Codes: C08F 2500/24 : Polymer with special particle form or size
• CPC Class Codes: C08F 4/6465 : containing silicium
• CPC Class Codes: C08F 4/6494 : containing oxygen
• CPC Class Codes: C08F 4/651 : Pretreating with non-metals or metal-free compounds

Abstract

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.

Claims

1. A catalyst composition comprising:

a procatalyst composition;

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), and a SCA1;

SCA2 mole ratio from 0.1-1.0;

1.

2. The catalyst composition of claim 1 wherein the procatalyst composition comprises an internal electron donor comprising a bidentate composition.

3. The catalyst composition of any of claims 1-2 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.

4. The catalyst composition of any of claims 1-3 wherein SCA2 is selected from the group consisting of a diethoxysilane, a triethoxysilane, a tetraethoxysilane, a trimethoxysilane, a diether, a dialkoxybenzene, a dimethoxysilane containing two linear alkyl groups, a dimethoxysilane containing two alkenyl groups, and combinations thereof.

5. The catalyst composition of any of claims 1-4 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.

6. The catalyst composition of any of claims 1-5 comprising an aluminum-containing cocatalyst and a mole ratio of A1 to M-EED less than about 6.0.

7. The catalyst composition of any of claims 1-6 comprising a mole ratio of total-SCA to ALA less than 1.0.

8. The catalyst composition of any of claims 1-7 wherein the catalyst composition is a self-limiting catalyst composition.

9. The catalyst composition of any of claims 1-8 wherein SCA1 comprises dicyclopentyldimethoxysilane.

10. The catalyst composition of any of claims 1-9 wherein SCA2 is selected from the group consisting of methylcyclohexyldiethoxysilane, di-isobutyldiethoxysilane, n-propylttiethoxysilane, tetraethoxysilane, di-n-butyl-dimethoxysilane, benzyltriethoxysilane, but-3-enyltriethoxysilane, 1-(triethoxysilyl)-2-pentene, (triethoxysilyl)cyclohexane, and combinations thereof.

11. The catalyst composition of any of claims 1-10 wherein the ALA comprises isopropyl myristate.

12. 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 a procatalyst, a cocatalyst and a mixed external electron donor (M-EED) comprising a first selectivity control agent (SCA1), a second selectivity control agent (SCA2), and an activity limiting agent (ALA); 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.

13. The process of claim 12 comprising self-limiting the polymerization when the temperature in the polymerization reactor is greater than about 100°

C.

14. The process of any of claims 12-13 comprising forming a propylene-based polymer comprising at least about 5 ppm ALA.

15. The process of any of claims 12-14 comprising forming an uncracked propylene-based polymer.

16. A propylene-based polymer comprising at least about 5 ppm of an activity limiting agent, the propylene-based polymer having a melt flow rate greater than about 50 g/10 min as measured in accordance with ASTM D 1238-01 at 230°

C., 2.16 kg.

17. The propylene-based polymer of claim 16 wherein the propylene-based polymer is uncracked.

18. The propylene-based polymer of any of claims 16-17 wherein the propylene-based polymer is a propylene homopolymer.

19. The propylene-based polymer of any of claims 16-18 comprising a property selected from the group consisting of a xylene solubles content less than about 4 wt %, a silicon content less than about 100 ppm, a post-reactor oligomer content less than about 3000 ppm, a T_MF greater than about 165°

C., and combinations thereof.

20. The propylene-based polymer of any of claims 16-19 wherein the melt flow rate is greater than about 100 g/10 min.