Monomer recovery process for contaminated polymers
AssigneeE. I. Du Pont de Nemours and Company
InventorFrancis G. Gallagher
Life of this patent
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Abstract
An improved process for recovering reaction products from polymers such as polyesters or polyamides, especially those having a desired polymer level below about 98%. The process involves depolymerization and vapor phase extraction of monomers in the presence of a solid support.
Claims20
A process for recovering reaction products from a reaction mass that comprises a starting polymer, wherein said polymer is a polyester or polyamide having about 2% to 70% by weight non-polymer contaminants, which process comprises:
- (a) depolymerizing the polymer by means of a depolymerizing agent to yield volatile reaction products;
- (b) vapor-phase stripping the volatile reaction products to yield a stripping-agent/product distillate;
- wherein said depolymerization and vapor-phase stripping is carried out in the presence of a solid support that comprises from about 5% to 99% by weight of the reaction mass, which solid support is solid under the conditions of steps (a) and (b), such that a suspended bed is formed and the quantity and rate of recovery of reaction products is enhanced over that obtained in the absence of said solid support;
- and
- (c) recovering the reaction products from the stripping-agent/product distillate while leaving non-volatile residue material with the support material.
A process for recovering reaction products from a reaction mass that comprises a starting polymer, wherein said polymer is a polyester or polyamide having about 2% to 70% by weight non-polymer contaminants, which process comprises:
- (a) depolymerizing the polymer by means of a depolymerizing agent to yield volatile reaction products;
- (b) vapor-phase stripping the volatile reaction products to yield a stripping-agent/product distillate;
- wherein said depolymerization and vapor-phase stripping is carried out in the presence of a support material selected from the group consisting of glass, carbon fiber, mineral, metal, ceramic, wood, aramid, and non-depolymerized residual polymer, which support material comprises from about 5% to 99% by weight of the reaction mass, which support material is solid under the conditions of steps (a) and (b), such that a suspended bed is formed in which the support material provides porosity for gas passage and surface area for gas/polymer and gas/oligomer contacting, thereby enhancing the quantity and rate of recovery of reaction products over that obtained in the absence of said support material;
- and
- (c) recovering the reaction products from the stripping-agent/product distillate while leaving non-volatile residue material with the support material.
Dependencies are inferred from the claim text.