Patent ID: 11866541
Assignee: KRATON CORPORATION
Field: Macromolecular chemistry, polymers (Chemistry)
Classification: CPC C  Y | IPC C

Claim 0:
1. A method to purify a polymer, comprising:
providing a polymer from a polymerization process employing at least a monomer or a comonomer as a feedstock, wherein the monomer or the comonomer is selected from the group consisting of organic polar monomers, inorganic monomers, vinyl aromatic monomers, conjugated dienes, and mixtures thereof, and
wherein the polymer is in molten or solid form, and the polymer contains at least an impurity to be removed;
wherein the impurity is selected from unreacted monomer or comonomer, catalyst residues, oligomers, by-products, impurities in the monomer or comonomer, solvents, residual processing aids, additives, modifiers, diluents, chelating agents, solvent modifiers, chain terminating agents, chain transfer agents, coupling agents, dimers, trimers, metals, catalyst decomposition products, polymer fractions, catalytic solvents, salts, acids, bases, odor-causing compounds, and mixtures thereof;

contacting the polymer in molten or solid form containing the impurity with a fluid solvent having a standard boiling point less than about 70° C. in an extraction vessel at a temperature from 80° C. to about 280° C. and at a pressure from 150 psig (1.03 MPa) to 8,000 psig (55.16 MPa),
wherein the pressure and temperature being controlled for the polymer to be essentially insoluble in the fluid solvent or for the polymer to dissolve into the fluid solvent, for the fluid solvent to extract at least 10% of the impurity from the polymer;

recovering a purified polymer by controlling the pressure and temperature to remove the extracted impurity from the purified polymer; and
collecting the extracted impurity.