Fluid assisted devolatilization
AssigneeNovacor Chemicals (International) S.A.
InventorJohn P. Skilbeck
Life of this patent
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Abstract
A polymer melt may be devolatilized to less than 500, preferably less than 150 ppm of residual volatile material by injecting into the melt an amount of fluid which will condense but not freeze at pressures of less than about 20 mm Hg, in an amount greater than the amount of residual volatile material in the polymer melt, typically not more than about 10 weight % and passing the melt through a zone of pressure of 8 mm of Hg or less at a temperature of from 200.degree. to 350.degree. C.
Claims11
A process for reducing the amount of residual monomer and solvent to less than 75 parts per million in a polymer or polymer blend, containing less than 1 weight % of such residual monomer, dimer, trimer and solvent, which process comprises:
- (i) heating and maintaining said polymer or polymer blend at a temperature from 200.degree.-270.degree. C.;
- (ii) injecting into said polymer or polymer blend an amount of an organic fluid greater than the amount of residual monomer, dimer, trimer and solvent in said polymer or polymer blend but less than 1 weight %, said injection being at temperature of from 200.degree.-270.degree. C. and pressures from 500 to 1500 psi and said organic fluid being selected from the group consisting of C.sub.1-4 alkanols and C.sub.1-4 ketones:
- and
- (iii) passing said polymer or polymer blend in the form of strands vertically through a flash chamber devolatilizer maintained at a temperature from 225.degree.-235.degree. C. and which has a pressure maintained at less than 5 torr.
Dependencies are inferred from the claim text.