Granted Patent B2

US 7,420,021 · App. 10/568,981 · Granted Sep 2, 2008

Abstract

Claims (21)

1. A catalyst composition for the polymerization of propylene or mixtures of propylene and one or more copolymerizable comonomers, said catalyst composition comprising one or more Ziegler-Natta procatalyst compositions comprising:

one or more transition metal compounds and one or more monoesters of aromatic carboxylic acid internal electron donors;

one or more aluminum containing cocatalyst; and

a mixture of two or more different selectivity control agents (SCA), said SCA mixture comprising from 98.5 to 99.9 mol percent of one or more esters of one or more aromatic monocarboxylic acids or substituted derivatives thereof, and from 1.5 to 0.1 mol percent of one or more alkoxysilane compounds.

2. The catalyst composition of claim 1 wherein the internal electron donor is ethyl benzoate.

3. The catalyst composition of claim 1 wherein the SCA mixture comprises ethyl p-ethoxybenzoate and an alkoxysilane containing two or three methoxy groups.

4. The catalyst composition of claim 1 wherein the alkoxysilane is dicyclopentyldimethoxysilane or methylcyclohexyldimethoxysilane.

5. A catalyst composition according to claim 1 wherein the total quantity of selectivity control agent employed provides a molar ratio, based on transition metal, from 1 to 100.

6. The catalyst composition according to claim 1 wherein the SCA mixture comprises from 98.5 to 99.5 mol percent of one or more alkyl esters of one or more aromatic monocarboxylic acids or substituted derivatives thereof, and from 1.5 to 0.5 mol percent of one or more alkoxysilane compounds.

7. The catalyst composition of claim 1 wherein the SCA mixture comprises from 98.6 to 99.0 mol percent of one or more alkyl esters of one or more aromatic monocarboxylic acids or substituted derivatives thereof, and from 1.4 to 1.0 mol percent of one or more alkoxysilane compounds.

8. The catalyst composition of claim 1 wherein the alkoxysilane is selected from the group consisting of diisopropyldimethoxysilane, diisobutyldimethoxysilane, and isobutylisopropyldimethoxysilane.

9. The catalyst composition of claim 1 wherein the SCA mixture comprises ethyl p-ethoxybenzoate and an alkoxysilane selected from the group consisting of dicyclopentyldimethoxysilane, methylcyclohexyldimethoxysilane, and n-propyltrimethoxysilane.

10. The catalyst composition of claim 1 wherein the Ziegler-Natta procatalyst composition is a morphology controlled procatalyst.

11. A polymerization method comprising:

contacting propylene or a mixture of propylene and one or more copolymerizable comonomers under polymerization conditions at a temperature from 45 to 100° C. with a catalyst composition comprising one or more Ziegler-Natta procatalyst compositions comprising one or more transition metal compounds and one or more internal electron donors selected from the group consisting of esters of aromatic monocarboxylic acids, one or more aluminum containing cocatalysts; and a mixture of two or more different selectivity control agents, said SCA mixture comprising from 98.5 to 99.9 mol percent of one or more esters of one or more aromatic monocarboxylic acids or substituted derivatives thereof, and from 1.5 to 0.1 mol percent of one or more alkoxysilane compounds.

12. The method of claim 11 conducted at a temperature from 60 to 85° C.

13. The method of claim 11 wherein the internal electron donor is ethyl benzoate.

14. The method of claim 11 wherein the SCA mixture comprises ethyl p-ethoxybenzoate and a dimethoxysilane.

15. The method of claim 11 wherein the alkoxysilane is dicyclopentyldimethoxysilane or methylcyclohexyldimethoxysilane.

16. The method according to claim 11 conducted under gas phase polymerization conditions.

17. The method according to claim 11 conducted in more than one reactor operating in series.

Assignments (7)