Patent ID: 9663647
Date: 2017-05-30
CPC Classifications: C08F,C08L

Claim:
1. A process for producing a propylene impact copolymer (ICOP), the process comprising the steps of: feeding propylene monomer and optionally one or more first comonomers into a first reactor; feeding into the first reactor a catalyst mixture comprising (1) a Ziegler-Natta catalyst composition comprising (a) a transition metal compound, and (b) an internal electron donor, (2) a cocatalyst, and (3) an external donor comprising (a) an activity limiting agent and (b) a selectivity control agent; contacting the propylene with the catalyst mixture under first polymerization conditions to polymerize propylene and the optionally one or more first comonomers to form an active propylene-based polymer; transferring at least a portion of the first reactor contents to a second reactor, the first reactor contents comprising the active propylene-based polymer, unreacted propylene monomer, and the catalyst mixture; feeding additional activity limiting agent, additional selectivity control agent and, optionally additional cocatalyst and one or more second comonomers into the second reactor; and maintaining the second reactor at a second reactor temperature in a range that is sufficient to allow copolymerization of the active propylene-based polymer, unreacted propylene monomer and the optionally one or more second comonomers to form the propylene impact copolymer (ICOP), wherein the second reactor temperature is below 70° C.