Producing propylene impact copolymers and products
A process for producing a propylene impact copolymer (ICOP), the process comprising the steps of feeding propylene and optionally one or more first comonomers into a first reactor; feeding into the first reactor a catalyst mixture; contacting the propylene with the catalyst mixture under first polymerization conditions to form an active propylene-based polymer; transferring at least a portion of the first reactor contents to a second reactor; 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 to form the propylene impact copolymer (ICOP), wherein the second reactor temperature is below 70° C.
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.
2. The process of claim 1 in which the optionally one or more first comonomers are not fed into the first reactor.
3. The process of claim 1 in which the optionally one or more first comonomers are fed into the first reactor.
4. The process of claim 1 in which the cocatalyst is triethylaluminum.
5. The process of claim 1 in which the optionally additional cocatalyst is not fed into the second reactor.
6. The process of claim 1 in which the optionally one or more first comonomers comprise one of a C 2 or C 4 -C 8 alpha-olefin.
7. The process of claim 1 in which the optionally one or more second comonomers comprise one of a C 2 or C 4 -C 8 alpha-olefin.
8. The process of claim 1 , in which the optionally one or more first comonomers are the same as the optionally one or more second comonomers.
9. The process of claim 1 , in which the optionally one or more first comonomers are different from the optionally one or more second comonomers.
10. The process of claim 1 in which the first and second reactors are fluid-bed reactors.
11. The process of claim 1 in which the second reactor temperature does not exceed 68° C.
12. The process of claim 1 in which the second reactor temperature does not exceed 65° C.
13. The process of claim 1 in which the weight fraction of rubber material in the propylene impact copolymer (ICOP) is greater than or equal to 25 wt %.
14. A propylene impact copolymer (ICOP) manufactured according to the process of claim 1 .
15. A propylene impact copolymer (ICOP) manufactured according to the process of claim 12 .