Removing gelled unsaturated elastomers from polymerization equipment associated with their production
A process for removing residual polymer from polymerization equipment by combining a degelling agent, residual polymer, and solvent.
1. A process for treating residual polymer in polymerization equipment comprising:
combining residual polymer, solvent, and a degelling agent that comprises a penta-coordinated or hexa-coordinated transition metal carbene complex, where the transition metal is selected from the group consisting of ruthenium and osmium.
2. The process of claim 1 , where the degelling agent can be represented by the formula
where M is ruthenium or osmium, L and L′ each independently comprise any neutral electron donor ligand, A and A′ each independently comprise an anionic substituent, R 3 and R 4 independently comprise hydrogen or an organic group, and c is an integer from 0 to about 5, or where two or more of R 3 , R 4 , L, L′, A, and A′ combine to form a bidentate substituent.
3. The process of claim 1 where the degelling agent comprises a Grubbs or Hoveyda-Grubbs type metathesis catalyst.
4. The process of claim 1 , where the amount of degelling agent present comprises from about 0.001 to about 20 millimoles of metal per 100 grains of residual polymer.
5. The process of claim 1 , where the residual polymer includes at least one metathesis-reactive external double bond per every about 1,000 monomer units.
6. The process of claim 5 , where the process is devoid of added olefin.
7. The process of claim 1 , where the residual polymer contains additives, contaminants or impurities.
8. The process of claim 1 , where the process further comprises the step of pre-mixing the degelling agent and a portion of the solvent prior to combining residual polymer, solvent, and degelling agent.
9. A process for removing residual polymer from a polymerization reactor comprising:
combining residual polymer, solvent, and a degelling agent that comprises a penta-coordinated or hexa-coordinated transition metal carbene complex, where the transition metal is selected from the group consisting of ruthenium and osmium, in a polymerization reactor for a time sufficient to degel at least a portion of the residual polymer and the residual polymer in the solvent; and
removing the degelling agent, solvent, and at least a portion of the degelled residual polymer from the reactor.
10. The process of claim 9 , where the degelling agent can be represented by the formula
where M is ruthenium or osmium, L and L′ each independently comprise any neutral electron donor ligand, A and A′ each independently comprise an anionic substituent. R 3 and R 4 independently comprise hydrogen or an organic group, and c is an integer from 0 to about 5, or where two or more of R 3 , R 4 L, L′, A, and A′ combine to form a bidentate substituent.
11. The process of claim 9 , where the degelling agent comprises a Grubbs or Hoveyda-Grubbs type metatheses catalyst.
12. The process of claim 9 , where the amount of degelling agent present comprises from about 0.001 to about 20 millimoles of metal per 100 grams of residual polymer.
13. The process of claim 9 , where the residual polymer includes at least one metathesis-reactive external double bond per every about 1,000 monomer units.
14. The process of claim 13 , where the process is devoid of added olefin.
15. The process of claim 9 , where the residual polymer contains additives, contaminants or impurities.
16. The process of claim 9 , where the process further comprises the step of pre-mixing the degelling agent and a portion of the solvent prior to combining residual polymer, solvent, and degelling agent.
17. In a process for the removal of residual polymer from polymerization equipment, the improvement comprising the step of combining a degelling agent that comprises a penta-coordinated or hexa-coordinated transition metal carbene complex with the residual polymer, where the transition metal is selected from the group consisting of ruthenium and osmium.