Depolymerization method for resource recovery from polymeric wastes
AssigneesS-P Reclamation, Inc., John S. Schwab
InventorGerald M. Platz
Life of this patent
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Abstract
Scrap rubber chunks from used tires are processed and the monomeric chemicals from which the tire rubber was synthesized are recovered. Rubber chunks reduced to a finely divided size are exposed to gaseous ozone to break down the cross-linked structure of the rubber. Subsequent thermal depolymerization occurs in a reactor chamber. Finely divided silica is introduced within the reactor to prevent agglomeration of rubber particles and to enhance the maintenance of a uniform reactor temperature. Reduced pressure within the reactor permits rapid removal of monomer vapors. Once the monomer vapors are separated, silica and carbon residues are recovered separately for either recycle or disposal.
Claims24
A process for recovering a monomer from a vulcanized addition polymer feedstock formed from the monomer, comprising the steps of:
- (a) exposing the addition polymer feedstock to gaseous ozone under conditions sufficient to rupture chemical bonds formed during the vulcanization process of the addition polymer feedstock and thereby form one or more intermediate products;
- (b) mixing the intermediate products of step (a) with silica to form a mixture;
- (c) heating the mixture formed in step (b) to a temperature and for a time sufficient to depolymerize the addition polymer and form the monomer;
- and
- (d) removing the monomer following its formation from the mixture.
A process for the recovering more than one monomer from a vulcanized addition copolymer feedstock formed from multiple monomers, comprising the steps of:
- (a) exposing the addition copolymer feedstock to gaseous ozone under conditions sufficient to rupture chemical bonds formed during the vulcanization process of the addition copolymer feedstock and thereby form one or more intermediate products;
- (b) mixing the intermediate products of step (a) with silica to form a mixture;
- (c) consecutively heating within a series of close coupled reaction zones the mixture formed in step (b) to temperatures and for times sufficient to depolymerize the addition copolymer and form more than one monomer;
- and
- (d) removing each monomer following its formation from the mixture.
Dependencies are inferred from the claim text.