Granted Patent B2

US 9,796,796 · App. 12/674,485 · Granted Oct 24, 2017

Abstract

Claims (8)

1. A catalyst composition for polymerization of propylene comprising:

one or more Ziegler-Natta procatalyst compositions comprising a mixed magnesium/titanium compound and an internal electron donor comprising diisobutyl phthalate;

one or more aluminum containing cocatalysts; and

a non-silane selectivity control agent (SCA) comprising a mixture at ethyl p-ethoxy benzoate activity limiting agent (ALA) and 2,2,6,6-tetramethylpiperidine selectivity determining agent (SDA), wherein the mole percent of ALA is greater than the mole percent of SDA;

wherein the ALA is present in an amount from 60 mole percent to 95 mole percent of total SCA, and the SDA is present in an amount from 5 mole percent to 40 mole percent of total SCA; and

wherein the catalyst composition exhibits a normalized activity ratio A100/A67 of 35% or less, wherein the normalized activity ratio is defined as A100/A67 where A100 is the activity at temperature 100° C. and A67 is die activity at 67° C. and activity is defined as the weight of polymerized propylene per weight catalyst composition per hour at the indicated temperature, and wherein a molar ratio of aluminum to total SCA is from 0.5:1 to 4:1; whereby the catalyst composition is self-extinguishing.

2. The catalyst composition of claim 1 wherein the catalyst composition further has a normalized activity ratio A115/A67 from 3% to 5%, wherein the normalized activity ratio is defined as A115/A67, where A115 is the activity at temperature 115° C. and A67 is the activity at 67° C.

3. The catalyst composition of claim 1 wherein the catalyst composition has a normalized activity ratio A100/A67 of 30% or less, wherein the normalized activity ratio is defined as A100/A67, where A100 is the activity at temperature 100° C. and A67 is the activity at 67° C.

Assignments (16)