Rayon fibers containing starch

Abstract

Rayon fibers made by spinning a viscose containing dissolved starch. Starch grains may be slurried in water, then made alkaline with NaOH to form a solution and then added to viscose.

What is claimed is  .[.1. Process for preparing starch-containing rayon fibers which comprises forming a slurry of starch granules in aqueous medium, adding sodium hydroxide (NaOH) to said slurry to produce an aqueous alkaline solution of starch, blending said solution with viscose, extruding the starch-containing viscose in fiber form and regenerating the cellulose in the extruded viscose to form starch-containing regenerated cellulose fibers, said starch having an amylopectin content of at least 60 percent..].  .[.2. Process as in claim 1 in which the proportion of starch is about 5 to 100% b.o.c..]. .[.3. Process as in claim 1 in which the proportion of starch is about 5 to 25% b.o.c..]. .[.4. Process as in claim 1 in which the porportion of starch is about 10 to 20% b.o.c..]. .[.5. Process as in claim 1 in which the NaOH concentration in said solution is between 2 and 41/2%, based on the weight of water and NaOH and said granules are of corn starch..]. .[.6. Process as in claim 5 in which the concentration of the starch in solution is about 6 to 20%..]. .[.7. Process as in claim 1 in which the NaOH concentration in said solution is such that in the "microscope method" the grain boundaries disappear..]. .[.8. Process as in claim 7 in which the concentration of the starch in solution is about 6 to 20%..]. .[.9. Process as in claim 1 in which said slurry contains a starch chain-splitting agent active in alkaline 
     
        medium..]. 10. Process as in claim .[.9.]. .Iadd.29 .Iaddend.in which said 
     
     
        chain-splitting agent comprises hydrogen peroxide. 11. Process as in claim 10 in which the concentration of H 2  O 2  is at least 0.01% based 
     
     
        on the weight of water. 12. Process as in claim .[.9.]. .Iadd.29 .Iaddend.in which the proportion of chain-splitting agent is such as to produce the alkaline starch solution having a concentration of 14 to 20% starch and a viscosity of about 35-170 poises, said viscosity being lower than that of a corresponding starch solution which has not been subjected to said chain-splitting agent.  .[.13. Process for preparing starch-containing rayon fibers which comprises dissolving corn starch granules in an aqueous alkaline medium which contains between 2 and 41/2% NaOH based on the total weight of water and NaOH, the concentration of starch in the resulting solution being about 6 to 20%, and blending said solution with viscose and extruding the starch-containing viscose in fiber form and regenerating the cellulose in the extruded viscose to form starch-containing regenerated cellulose fibers, said starch having an 
     
     
        amylopectin content of at least 60 percent..]. 14. Process for producing rayon fibers which comprises extruding a viscose solution, containing about 5 to 25% dissolved starch b.o.c., to form a plastic stretchable fiber and then stretching said plastic fiber at least 50% to form fibers having a tenacity of at least about 2 grams per denier.[., said starch 
     
     
        having an amylopectin content of at least 60 percent.].. 15. Process as in claims 14 in which said viscose solution is extruded into an aqueous coagulating bath containing H 2  SO 4  and at least 0.5% ZnSO 4   
     
     
        and is stretched at a temperature about 70° C. 16. Process as in claim 15 in which said coagulating bath containing about 6-13% H 2   
     
     
        SO 4  about 0.5-5% ZnSO 4  and about 12-25% Na 2  SO 4 . 
     
     
        17. Product of the process of claim 14. 18. Process as in claim 14 in which the viscose contains a regeneration retarder, the stretching is at 
     
     
        least 100% and the resulting fiber has a wet modulus above 7. 19. Product 
     
     
        of the process of claim 18. 20. Process as in claim 15 in which the stretching conditions are such as to produce coagulated regenerated filaments having a skin and a partly exposed core and the stretched filaments are cut into staple fibers and then relaxed to form crimped 
     
     
        fibers. 21. Product of the process of claim 20. 22. Process .Iadd.as in claim 29 .Iaddend.which comprises extruding in fiber form a viscose containing about 5 to 100% dissolved starch b.o.c. and an anionic polymer dispersed in said viscose and coagulating the extruded solution to form fibers containing dispersed anionic polymer and having an increased fluid holding capacity because of the presence of said anionic polymer.[., said 
     
     
        starch having an amylopectin content of at least 60 percent.].. 23. Process as in claim 22 in which the amount of said anionic polymer 
     
     
        dispersed in said viscose is at least about 10% b.o.c. 24. Product of the 
     
     
        process of claim 22. 25. Process as in claim 23 in which said anionic polymer has at least about 0.2 gram equivalent of salt forming anionic 
     
     
        groups per 100 grams. 26. Process as in claim 25 in which said anionic 
     
     
        polymer comprises a sodium polyacrylate. 27. Process as in claim 25 in 
     
     
        which said anionic polymer comprises sodium carboxymethyl cellulose. 28. Process .Iadd.as in claim 29 .Iaddend.which comprises extruding in fiber form a viscose containing about 5 to 100% dissolved starch b.o.c. and polyvinylpyrollidone and coagulating the extruded solution to form fibers having increased fluid holding capacity because of the presence of said polyvinylpyrollidone.[., said starch having an amylopectin content of at least 60 percent.].. .Iadd. 29. Process for preparing starch-containing rayon fiber which comprises forming a slurry of starch granules in aqueous medium, adding an aqueous solution of a starch-splitting agent active in alkaline medium to said slurry, the proportion being about 0.003 by 0.015 moles of agent per mole of starch in slurry, adding sodium hyroxide (NaOH) to said slurry to produce an aqueous alkaline solution of starch, blending said solution with viscose, extruding the starch-containing viscose in fiber form and regenerating the cellulose in the extruded viscose to form starch-containing regenerated cellulose fibers, said starch having an amylopectin content of at least 60%. .Iaddend.