Patent US3884850A successfully refreshed from Google Patents.
US3884850A
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Continuous atmospheric depolymerization of polyester
Assignee: Celanese Corp
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Filing: 1970-02-13
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Granted: 1975-05-20
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Expires: 1990-02-13
Abstract
Abstract Process for the depolymerization of high molecular weight, i.e., fiber-formable, polyesters to low molecular weight oligomer depolymerizate in a continuous process at atmospheric pressure.
Inventors
- 👤 Henry S Ostrowski
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 14:43
CPC Classifications
C; C08; C08J; C08J11/00; C08J11/04; C08J11/10; C08J11/18; C08J11/22; C08J11/24; C08G; C08G63/00; C08G63/78; C08G63/785; C08J2367/00; C08J2367/02; Y; Y02; Y02W; Y02W30/00; Y02W30/50; Y02W30/62
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
139 words
A PROCESS FOR CONTINUOUSLY DEPOLYMERIZING HIGH MOLECULAR WEIGHT LINEAR POLYESTER SCRAP SAID POLYESTER BEING THE POLYCONDENSATION PRODUCT OF A DIHYDRIC ALCOHOL AND A DICARBOXYLIC ACID COMPRISING DISSOLVING SAID POLYESTER SCRAP AT AN ELEVATED TEMPERATURE IN A SOLVENT WHICH IS LIQUID AT THE DISSOLVING TEMPERATURE, SAID SOLVENT BEING SELECTED FROM THE GROUP CONSITING OF MONOMERIC ESTER, BIESTER, LOWE MOLECULAR WEIGHT ESTERS AND OLIGOMERS OF SAID HIGH MOLECULAR WEIGHT POLYESTER TO FORM A DEPOLYMERIZATION MIXTURE, CONTINUOUSLY ADDING WITH SAID SCRAP POLYESTER, DIHYDRIC ALCOHOL CORRESPONDING TO THE DIHYDRIC ALCOHOL OF SAID POLYESTER SCRAP IN A STOICHIOMETRIC EXCESS SUFFICIENT TO PRODUCE THE DESIRED DEGREE OF DEPOLYMERIZATION TO AT LEAST AN OLIGOMER, EFFECTING SAID DEPOLYMERIZATION UNDER ATMOSPHERIC PRESSURE AT A TEMPERATURE ABOVE THE BOILING POINT OF SAID DIHYDRIC ALCOHOL BUT BELOW THE MELTING POINT OF SAID POLYESTER AND CONTINUOUSLY RECOVERING LOWER MOLECULAR WEIGHT DEPOLYMERIZATE.
Claim 2
Dependent Claim
139 words
A PROCESS FOR CONTINUOUSLY DEPOLYMERIZING HIGH MOLECULAR WEIGHT LINEAR POLYESTER SCRAP SAID POLYESTER BEING THE POLYCONDENSATION PRODUCT OF A DIHYDRIC ALCOHOL AND A DICARBOXYLIC ACID COMPRISING DISSOLVING SAID POLYESTER SCRAP AT AN ELEVATED TEMPERATURE IN A SOLVENT WHICH IS LIQUID AT THE DISSOLVING TEMPERATURE, SAID SOLVENT BEING SELECTED FROM THE GROUP CONSITING OF MONOMERIC ESTER, BIESTER, LOWE MOLECULAR WEIGHT ESTERS AND OLIGOMERS OF SAID HIGH MOLECULAR WEIGHT POLYESTER TO FORM A DEPOLYMERIZATION MIXTURE, CONTINUOUSLY ADDING WITH SAID SCRAP POLYESTER, DIHYDRIC ALCOHOL CORRESPONDING TO THE DIHYDRIC ALCOHOL OF SAID POLYESTER SCRAP IN A STOICHIOMETRIC EXCESS SUFFICIENT TO PRODUCE THE DESIRED DEGREE OF DEPOLYMERIZATION TO AT LEAST AN OLIGOMER, EFFECTING SAID DEPOLYMERIZATION UNDER ATMOSPHERIC PRESSURE AT A TEMPERATURE ABOVE THE BOILING POINT OF SAID DIHYDRIC ALCOHOL BUT BELOW THE MELTING POINT OF SAID POLYESTER AND CONTINUOUSLY RECOVERING LOWER MOLECULAR WEIGHT DEPOLYMERIZATE.
Claim 3
Dependent Claim
20 words
The process of claim 1 wherein said polyester is selected from the group consisting of polyethylene, polytrimethylene and polytetramethylene terephthalates.
Claim 4
Dependent Claim
25 words
The process of claim 1 wherein the polyester is polyethylene terephthalate and the temperature of depolymerization is within the range of about 220* to 250*C.
Claim 5
Dependent Claim
13 words
The process of claim 3 wherein the temperature is about 230* to 245*C.
Claim 6
Dependent Claim
11 words
The process of claim 4 wherein the solvent is bis-(hydroxyethyl) terephthalate.
Claim 7
Dependent Claim
19 words
The process of claim 1 wherein the average residence time in the depolymerizer is about 1 to 5.0 hours.
Claim 8
Dependent Claim
11 words
The process of claim 1 wherein the polyester is polytetramethylene terephthalate.
Claim 9
Dependent Claim
28 words
The process of claim 1 wherein the dihydric alcohol is used in an amount of up to about 15 percent by weight in excess of the stoichiometric requirement.
Claim 10
Dependent Claim
91 words
A process for continuously depolymerizing polyethylene terephthalate scrap to an oligomer mixture which comprises charging bis-(hydroxyethyl) terephthalate to a depolymerizer operating at about 220*-250*C under atmospheric pressure, continuously adding said polyethylene terephthalate and an amount of ethylene glycol up to about 15% by weight in excess of that required for stoichiometric depolymerization to an oligomer mixture of average chain length of about 2 to 3 monomer units based on terephthalic acid and a sufficient amount for maintenance of a continuous reaction to said depolymerizer, and continuously recovering said oligomer mixture therefrom.
Claim 11
Dependent Claim
91 words
A process for continuously depolymerizing polyethylene terephthalate scrap to an oligomer mixture which comprises charging bis-(hydroxyethyl) terephthalate to a depolymerizer operating at about 220*-250*C under atmospheric pressure, continuously adding said polyethylene terephthalate and an amount of ethylene glycol up to about 15% by weight in excess of that required for stoichiometric depolymerization to an oligomer mixture of average chain length of about 2 to 3 monomer units based on terephthalic acid and a sufficient amount for maintenance of a continuous reaction to said depolymerizer, and continuously recovering said oligomer mixture therefrom.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-05-19 | 1978-11-18 | 1979-05-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-19 | 1982-11-18 | 1983-05-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-19 | 1986-11-18 | 1987-05-20 | $7700.00 | Window Closed / Lapsed |