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AssigneesHoechst Aktiengesellschaft, Chemiefaser Lenzing Aktiengesellschaft
InventorsJoseph Cremer, Heinz Harnisch, Johannes Adolf Krassig, Johannes Hupfl, Werner Gschaider
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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.
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.
Dependencies are inferred from the claim text.