Patent US3974251A successfully refreshed from Google Patents.
US3974251A
Expired / Lapsed
US
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Production of flameproof fibers of regenerated cellulose
Assignee: Lenzing AG
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Filing: 1974-03-04
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Granted: 1976-08-10
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Expires: 1994-03-04
Abstract
Abstract Flame-retardant fibers of regenerated cellulose are produced by adding one or more flame-retardant phosphorus compounds to the viscose, extruding the viscose into a spinning bath and, if desired, stretching and after-treating the resulting filaments or staple fibers. The flame-retardant agent is a compound of the general formula PN.sub.x O.sub.y in which x stands for a number between 0.9 and 1.7 and y stands for a number between 1.2 and 0, where the y-values converge towards zero as the x-values increase. The flame-retardant agent is more particularly used in a proportion approximately between 5 and 30 weight %, based on the weight of the cellulose.
Inventors
- 👤 Joseph Cremer
- 👤 Heinz Harnisch
- 👤 Johannes Adolf Krassig
- 👤 Johannes Hupfl
- 👤 Werner Gschaider
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 22:07
CPC Classifications
D; D01; D01F; D01F2/00; D01F2/06; D01F2/08; D01F2/10
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
78 words
In a process for making flame-retardant regenerated cellulose fibers by adding flame-retardant phosphorus compounds to viscose, extruding the viscose containing mixture so obtained into a spinning bath and, if desired, stretching and after-treating the resulting filaments or staple fibers, the improvement comprising adding as the flame-retardant a compound selected from the group consisting of phosphorus nitride, triphosphorus pentanitride, tetraphosphorus hexanitride and mixtures thereof, the amount of the flame-retardant being approximately 5 - 30% by weight of the cellulose.
Claim 2
Dependent Claim
78 words
In a process for making flame-retardant regenerated cellulose fibers by adding flame-retardant phosphorus compounds to viscose, extruding the viscose containing mixture so obtained into a spinning bath and, if desired, stretching and after-treating the resulting filaments or staple fibers, the improvement comprising adding as the flame-retardant a compound selected from the group consisting of phosphorus nitride, triphosphorus pentanitride, tetraphosphorus hexanitride and mixtures thereof, the amount of the flame-retardant being approximately 5 - 30% by weight of the cellulose.
Claim 3
Dependent Claim
30 words
The process as claimed in claim 1, wherein between about 8 and 15 weight %, based on the weight of cellulose, of the flame-retardant is incorporated into the regenerated cellulose.
Claim 4
Dependent Claim
27 words
The process as claimed in claim 1, wherein a suspension or solution of the flame-retardant in a liquid compatible with the viscose is added to the viscose.
Claim 5
Dependent Claim
24 words
The process as claimed in claim 3, wherein the viscose-compatible liquid is water, sodium hydroxide solution or another liquid miscible with an aqueous medium.
Claim 6
Dependent Claim
18 words
The process as claimed in claim 4, wherein an inert organic liquid is used as the viscose-compatible liquid.
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) | 1979-08-10 | 1980-02-09 | 1980-08-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-08-10 | 1984-02-09 | 1984-08-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-08-10 | 1988-02-09 | 1988-08-10 | $7700.00 | Window Closed / Lapsed |