Depolymerization of substantially amorphous polyesters
AssigneeEastman Chemical Company
InventorsGeorge W. Tindall, Randall L. Perry, Art T. Spaugh, Jr.
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Abstract
Ester bonds are hydrolyzed in the conversion of substantially amorphous polyesters to their monomeric components, by being contacted with a mixture of (a) an alcohol, such as methanol, or glycol, (b) a polar aprotic solvent such as N-methyl-pyrrolidone or dimethyl sulfoxide and (c) an alkoxide or hydroxide such as sodium hydroxide.
Claims16
A process for the conversion of polyesters to their monomeric components comprising contacting a substantially amorphous polyethylene terephthalate having a crystallinity of no greater than 25% with a mixture of (a) at least one alcohol or glycol;
- (b) at least one polar aprotic solvent;
- and (c) at least one alkoxide or hydroxide for a sufficient time to convert at least a portion of said polyester to it's monomeric components;
- wherein said alcohol or glycol, said polar aprotic solvent, and said alkoxide or hydroxide are compatible, bringing at least a portion of said alkoxide or hydroxide into solution in the solvent mixture.
A process for the conversion of polyesters to their monomeric components comprising:
- I) heating a crystalline polyethylene terephthalate to form a melt,
- II) quenching said melt to form a substantially amorphous polyethylene terephthalate having a crystaliniity no greater than 25%, and
- III) contacting sad substantially amorphous polyethylene terephthalate with a mixture of (a) about 5 to 80 (vol) % methanol, (b) about 95 to 20 (vol) % of a polar aprotic solvent selected from the group consisting of dimethyl sulfoxide and N-methyl-pyrrolidone, and (c) an alkali metal hydroxide in molar excess, with respect to the ester bonds to be hydrolyzed, at a temperature between about room temperature and the boiling point of the mixture for a sufficient time to convert said substantially amorphous polyethylene terephthalate to its monomeric components.
A process for the conversion of polyesters to their monomeric components comprising:
- A) heating crystalline polyethylene terephthalate to form a melt, and
- B) quenching said melt into a liquid to form a substantially amorphous polyethylene terephthalate having a crystallinity no greater than 25%, wherein said substantially amorphous polyethylene terephthalate is contacted with a mixture of (a) about 5 to 80 (vol) % methanol, (b) about 95 to 20 (vol) % of a polar aprotic solvent selected from the group consisting of dimethyl sulfoxide and N-methyl-pyrrolidone, and (c) an alkali metal hydroxide in molar excess, with respect to the ester bonds to be hydrolyzed, in said polyethylene terephthalate and said liquid is at least one component of the mixture of (a), (b) and (c).
Dependencies are inferred from the claim text.