Olefin polymerization processes featuring in situ blending of an oil extension
View Patent ↗High molecular weight elastomers, such as ethylene-propylene-diene monomer (EPDM) polymers, are conventionally formulated with a post-polymerization oil extension to mitigate their high Mooney viscosity. Post-polymerization oil extension adds to processing costs and precludes use of polymerization facilities lacking oil extension capabilities. A low molecular weight polymer may be co-produced with a high molecular weight elastomer containing the same monomers, where the low molecular weight polymer may function in place of conventional oil extension. Polymerization methods may comprise: combining one or more olefinic monomers, a metallocene first catalyst component and a non-metallocene transition metal second catalyst component, and a solvent; and reacting the one or more olefinic monomers under solution polymerization conditions to form a polyolefin blend comprising first and second polyolefins having a bimodal molecular weight distribution. The non-metallocene second catalyst component may be a pyridylbisimine, quinolinyldiamido, pyridylamido, phenoxyimine, or bridged bi-aromatic complex.
1. A method comprising:
combining a reaction mixture comprising:
one or more olefinic monomers,
a first catalyst component comprising a metallocene and a second catalyst component comprising at least one non-metallocene transition metal complex selected from the group consisting of a pyridylbisimine complex, a quinolinyldiamido complex, a pyridylamido complex, a phenoxyimine complex, a bridged bi-aromatic complex, and any combination thereof, wherein a molar ratio of the second catalyst component to the first catalyst component ranges from about 3:1 to about 15:1, and
a solvent; and
reacting the one or more olefinic monomers under solution polymerization conditions to form a polyolefin blend comprising a first polyolefin and a second polyolefin, the polyolefin blend exhibits a bimodal molecular weight distribution and the second polyolefin has a higher weight average molecular weight than the first polyolefin, wherein the second polyolefin has a weight average molecular weight of about 150,000 or higher and the first polyolefin has a weight average molecular weight of about 50,000 or lower.
2. The method of claim 1 , wherein the first catalyst component promotes formation of the first polyolefin and the second catalyst component promotes formation of the second polyolefin.
3. The method of claim 1 , wherein the second catalyst component is a quinolinyldiamido complex.
4. The method of claim 3 , wherein the second catalyst component is a Hf or Zr quinolinyldiamido complex.
5. The method of claim 1 , wherein the second catalyst component is a Group 4 quinolinyldiamido complex.
6. The method of claim 1 , wherein the molar ratio of the second catalyst component to the first catalyst component ranges from about 3:1 to about 10:1.
7. The method of claim 1 , wherein the reaction mixture further comprises one or more activators.
8. The method of claim 7 , wherein the one or more activators are selected from the group consisting of an alumoxane and a non-coordinating anion activator.
9. The method of claim 7 , wherein the reaction mixture further comprises at least one alkylaluminum compound.
10. The method of claim 1 , wherein the solvent comprises at least one hydrocarbon solvent.
11. The method of claim 1 , wherein the one or more olefinic monomers comprise at least ethylene and propylene.
12. The method of claim 1 , wherein the one or more olefinic monomers comprise ethylene, propylene, and a diene monomer.
13. The method of claim 1 , wherein the reaction mixture is combined and reacted in a single reactor vessel to form the polyolefin blend.
14. The method of claim 1 , further comprising:
obtaining the polyolefin blend in a solution comprising the solvent.
15. The method of claim 1 , further comprising:
separating the polyolefin blend from the solvent to provide a substantially solvent-free polyolefin blend.
16. The method of claim 1 , wherein the first polyolefin has a weight average molecular weight ranging from about 10,000 to about 40,000.
17. The method of claim 1 , wherein the polyolefin blend comprises a higher mass percentage of the second polyolefin than the first polyolefin.
18. The method of claim 1 , wherein the polyolefin blend comprises about 20 wt. % to about 40 wt. % of the first polyolefin and about 60 wt. % to about 80 wt. % of the second polyolefin.
19. The method of claim 1 , wherein the bimodal molecular weight distribution exhibits a peak-to-peak molecular weight separation that is at least two orders of magnitude.
20. The method of claim 1 , further comprising:
selecting an amount of the first catalyst component sufficient to provide a substantially solvent-free polyolefin blend having a Mooney viscosity ML (1+4) about 50 MU or more, as measured using a Mooney viscometer.
21. The method of claim 1 , wherein the polyolefin blend has a Mooney viscosity ML (1+4) of about 50 MU to about 150 MU, as measured using a Mooney viscometer.