US3832411A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for the depolymerization of polytetrafluoroethylene
Assignee: Zeneca Inc
•
Filing: 1971-02-02
•
Granted: 1974-08-27
•
Expires: 1991-02-02
Abstract
Abstract High yield monomeric tetrafluoroethylene may be recovered from polytetrafluoroethylene and polytetrafluoroethylene composites by pyrolyzing the polymer in the presence of high temperature steam. The steam acts as a condensable carrier gas for the low molecular weight pyrolysis products and should be present in an amount such that the mole ratio of steam to pyrolysis products is at least one to one. The steam also acts as a means for heating the polymer to the necessary decomposition temperatures.
Inventors
- 👤 B Arkles
- 👤 R Bonnett
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 08:57
CPC Classifications
C; C07; C07C; C07C17/00; C07C17/361; C07C17/367
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
21 words
A method according to claim 1 wherein the polymeric tetrafluoroethylene is heated to a temperature of between about 780*F. and 1,400*F.
Claim 2
Dependent Claim
41 words
A method according to claim 1 wherein the polymeric tetrafluoroethylene is heated to a temperature of between about 800*F. and 1,100*F., and the mole ratio of steam to said pyrolysis products is between about 10 to 1 and 40 to 1.
Claim 3
Dependent Claim
21 words
A method according to claim 1 wherein the polymeric tetrafluoroethylene is heated by steam having a temperature of at least 950*F.
Claim 4
Dependent Claim
85 words
In a method for depolymerizing polymeric tetrafluoroethylene by pyrolysis, the improvement comprising heating polymeric tetrafluoroethylene at a pressure of at least atmospheric pressure and in the presence of high temperature steam sufficient to heat said polymeric tetrafluoroethylene to a temperature of at least about 780* F., said steam being present in an amount such that the mole ratio of steam to pyrolysis products is at least about 4 to 1, condensing the steam froM the mixture of pyrolysis products, and collecting the resulting pyrolysis products.
Claim 5
Dependent Claim
18 words
A method according to claim 5 wherein said steam has a temperature of between about 950*F. and 1,800*F.
Claim 6
Dependent Claim
26 words
A method according to claim 5 wherein the mole ratio of steam to said pyrolysis products is between about 10 to 1 and 40 to 1.
Claim 7
Dependent Claim
15 words
A method according to claim 5 wherein said polymeric tetrafluoroethylene is recycled scrap containing fillers.
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) | 1977-08-26 | 1978-02-25 | 1978-08-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-08-26 | 1982-02-25 | 1982-08-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-08-26 | 1986-02-25 | 1986-08-27 | $7700.00 | Window Closed / Lapsed |