Improvements relating to the cold-alkali process for the production of regenerated cellulosic fibers

Abstract

A method and processing facility for producing regenerated cellulosic fibers includes extruding a spinning solution into a coagulation bath which contains a salt and preferably an alkali to produce the fibers. The spinning solution may include cellulose dissolved in an aqueous solvent comprising NaOH and ZnO. The coagulation bath may have a pH-value of at least seven. The method may also include a continuous process of applying to the fibers in a never-dried state a crosslinking agent with two or more reactive groups and heating the fibers to a curing temperature while maintaining the never-dried condition to produce a reaction between the crosslinking agent and the cellulose of the fiber.

The invention claimed is: 
     
         1 . A method for producing regenerated cellulosic fibers, comprising the steps of:
 extruding a spinning solution into a coagulation bath which contains a salt to produce fibers, the spinning solution comprising cellulose dissolved in an aqueous solvent comprising NaOH and ZnO, the coagulation bath having a pH-value of at least seven,   applying to the fibers in a never-dried state a crosslinking agent with two or more reactive groups; and   heating the fibers to a curing temperature while maintaining the never-dried condition to produce a reaction between the crosslinking agent and the cellulose of the fibers.   
     
     
         2 . The method according to  claim 1 , wherein the crosslinking agent is applied on the fibers after the fibers have been partially washed. 
     
     
         3 . The method according to  claim 1 , wherein the crosslinking agent is applied on the fibers after the fibers have been washed, wherein the crosslinking agent is applied in combination with an inorganic alkali. 
     
     
         4 . The method according to  claim 1  wherein the crosslinking agent is applied to the fibers by directing the fibers through an application bath comprising the crosslinking agent. 
     
     
         5 . The method according to  claim 1 , wherein the step of heating of the fibers to a curing temperature further comprises at least one of the following steps:
 heating a fluid comprising the crosslinking agent to a temperature above the curing temperature before applying the crosslinking agent to the fibers, and   steaming the fibers after applying the crosslinking agent to the fibers.   
     
     
         6 . The method according to  claim 1 , wherein the crosslinking agent comprises a reactive dyestuff having two or more reactive groups. 
     
     
         7 . The method according to  claim 1 , wherein the crosslinking agent and a monolinking dyestuff are applied to the fibers. 
     
     
         8 . The method according to  claim 7 , wherein a monolinking dyestuff is applied to the fibers in combination with the crosslinking agent. 
     
     
         9 . The method according to  claim 1 , further comprising the step of incorporating a water-soluble polymeric alcohol into the fibers before the application of the crosslinking agent. 
     
     
         10 . A processing facility for producing regenerated cellulosic fibers, comprising:
 a coagulation bath containing a salt and having a pH-value of at least seven;   a spinneret configured to extrude a spinning solution into the coagulation bath to produce fibers, wherein the spinning solution comprising cellulose dissolved in an aqueous solvent comprising NaOH and ZnO;   a crosslinking facility configured to apply a crosslinking agent with two or more reactive groups to the fibers in a never-dried state; and   a curing facility configured to heat the fibers to a curing temperature while maintaining the never-dried condition to produce a reaction between the crosslinking agent and the cellulose of the fibers.   
     
     
         11 . The processing facility according to  claim 10 , wherein the crosslinking facility comprises an application bath in which the crosslinking agent is provided and applied to the fibers. 
     
     
         12 . The processing facility according to  claim 10 , further comprising a washing facility upstream from the crosslinking facility. 
     
     
         13 . A regenerated cellulosic fiber produced by a method comprising the steps of:
 extruding a spinning solution into a coagulation bath which contains a salt to produce fibers, the solution comprising cellulose dissolved in an aqueous solvent comprising NaOH and ZnO, the coagulation bath having a pH-value of at least seven,   applying to the fibers in a never-dried state a crosslinking agent with two or more reactive groups; and   heating the fibers to a curing temperature while maintaining the never-fried condition to produce a reaction between the crosslinking agent and the cellulose of the fibers.   
     
     
         14 . The regenerated cellulosic fiber according to  claim 13 , the fiber comprising the crosslinking agent in an amount of about 0.5% per weight to about 5% per weight based on a weight of the fiber when dry. 
     
     
         15 . A product made from a regenerated cellulosic fiber produced by a method comprising the steps of:
 extruding a spinning solution a coagulation bath which contains a salt to produce fibers, the solution comprising cellulose dissolved in an aqueous solvent comprising NaOH and ZnO, the coagulation bath having a pH-value of at least seven,   applying to the fibers in a never-dried state a crosslinking agent and the cellulose of the fibers,   wherein the product is selected from a list consisting of yarns, fabrics, textiles, home textiles, garments, nonwovens, hygiene products, upholstery, technical applications, filter material, and paper.   
     
     
         16 . A regenerated cellulosic fiber produced in a processing facility for producing regenerated cellulosic fibers comprising:
 a coagulation bath containing a salt and having a pH-value of at least seven;   a spinneret configured to extrude a spinning solution into the coagulation bath to produce fibers, wherein the spinning solution comprising cellulose dissolved in an aqueous solvent comprising NaOH and ZnO;   a crosslinking facility configured to apply a crosslinking agent with two or more reactive groups to the fibers in a never-dried state; and   a curing facility configured to heat the fibers to a curing temperature while maintaining the never-dried condition to produce a reaction between the crosslinking agent and the cellulose of the fibers.   
     
     
         17 . The regenerated cellulosic fiber according to  claim 16 , the regenerated cellulosic fiber comprising the crosslinking agent in an amount of about 0.5% per weight to about 5% per weight based on a weight of the fiber when dry. 
     
     
         18 . A product made from a regenerated cellulosic fiber produced in a processing facility for producing regenerated cellulosic fibers comprising:
 a coagulation bath containing a salt and having a pH-value of at least seven;   a spinneret configured to extrude a spinning solution into the coagulation bath to produce fibers, wherein the spinning solution comprising cellulose dissolved in an aqueous solvent comprising NaOH and ZnO;   a crosslinking facility configured to apply a crosslinking agent with two or more reactive groups to the fibers in a never-dried state; and   a curing facility configured to heat the fibers to a curing temperature while maintaining the never-dried condition to produce a reaction between the crosslinking agent and the cellulose of the fibers.   
     
     
         19 . The method according to  claim 2 , wherein the crosslinking agent is applied on the fibers after the fibers have been partially washed to a pH of between about 10 and about 12. 
     
     
         20 . The method according to  claim 3 , wherein the crosslinking agent is applied on the fibers after the fibers have been washed to a pH of between 5 and 11. 
     
     
         21 . The method according to  claim 1 , further comprising the step of applying a water-soluble polymeric alcohol in combination with the crosslinking agent.