US5294707A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Semi-continuous depolymerization of nylon 6 polymer
Assignee: BASF Corp
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Filing: 1993-02-25
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Granted: 1994-03-15
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Expires: 2013-02-25
Abstract
Abstract Polyamide is semi-continuously depolymerized by: (a) charging the polyamide to a depolymerization reactor containing 5 to 50% by weight of an unpolymerized catalyst; (b) melting the polyamide and subjecting the resultant melt to a flow of superheated steam to obtain a steam distillate; (c) separating amide monomers in the distillate from other volatiles therein; (d) when conversion to amide monomers is 40 to 90% complete, recharging polyamide to the depolymerization reactor; and (e) repeating steps (a)-(d) until a desired amount of polyamide is depolymerized.
Inventors
- 👤 Richard Kotek
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 03:40
CPC Classifications
C; C07; C07D; C07D201/00; C07D201/02; C07D201/12
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
92 words
A process for the semi-continuous depolymerization of nylon 6 comprising: (a) charging nylon 6 to a depolymerization reactor containing 5 to 50% by weight of unpolymerized catalyst; (b) melting the nylon 6 and subjecting the resultant melt to a flow of superheated steam to obtain a stream distillate; (c) separating caprolactam monomers in the distillate from other volatiles therein; (d) when conversion to caprolactam is 40 to 90% complete, recharging nylon 6 to the depolymerization reactor; and (e) repeating steps (a)-(d) until a desired amount of nylon 6 is converted to caprolactam.
Claim 2
Dependent Claim
92 words
A process for the semi-continuous depolymerization of nylon 6 comprising: (a) charging nylon 6 to a depolymerization reactor containing 5 to 50% by weight of unpolymerized catalyst; (b) melting the nylon 6 and subjecting the resultant melt to a flow of superheated steam to obtain a stream distillate; (c) separating caprolactam monomers in the distillate from other volatiles therein; (d) when conversion to caprolactam is 40 to 90% complete, recharging nylon 6 to the depolymerization reactor; and (e) repeating steps (a)-(d) until a desired amount of nylon 6 is converted to caprolactam.
Claim 3
Dependent Claim
27 words
The process of claim 1 wherein said charging is to a depolymerization reactor containing a catalyst selected from the group consisting of ortho-phosphoric acid and p-toluenesulfonic acid.
Claim 4
Dependent Claim
14 words
The process of claim 1 wherein said melting is to at least 270° C.
Claim 5
Dependent Claim
18 words
The process of claim 1 wherein said charging is to a depolymerization reactor containing an ortho-phosphoric acid catalyst.
Claim 6
Dependent Claim
19 words
The process of claim 4 wherein said recharging is when conversion to amide monomers is 40 to 85% complete.
Claim 7
Dependent Claim
21 words
The process of claim 4 wherein said charging is to a depolymerization reactor containing 5 to 25% by weight of catalyst.
Claim 8
Dependent Claim
18 words
The process of claim 1 wherein said charging is to a depolymerization reactor containing a p-toluenesulfonic acid catalyst.
Claim 9
Dependent Claim
19 words
The process of claim 7 wherein said recharging is when conversion to caprolactam monomers is 70 to 90% complete.
References Cited (Backward Citations)
US3182055A
Cited
US3939153A
Cited
US4107160A
Cited
US4605762A
Cited
JPS6020379A
Cited
US4620032A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-03-14 | 1997-09-13 | 1998-03-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-03-14 | 2001-09-13 | 2002-03-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-03-14 | 2005-09-13 | 2006-03-15 | $7700.00 | Window Closed / Lapsed |