Cationic cellulosic fibers and methods of making and using the same

Abstract

The present invention relates to cationic cellulosic fibers that are useful for preparing dyeable fabrics and garments, for example, garments that have a mélange effect and/or a denim-like in appearance.

What is claimed is: 
     
         1 . A cationic cellulosic fiber comprising:
 an outer layer comprising a plurality of covalently attached cationic moieties; and   an inner layer that is substantially free of cationic charge,   
       wherein a thickness ratio of the outer layer to the inner layer is in the range of about 10:1 to about 1:10, wherein the cationic moieties are derived from a quaternary ammonium salt. 
     
     
         2 . The cationic cellulosic fiber of  claim 1 , which is a yarn fiber. 
     
     
         3 . The cationic cellulosic fiber of  claim 1 , which is a warp yarn fiber. 
     
     
         4 . The cationic cellulosic fiber of  claim 1 , wherein the cationic moieties are derived from N-(3-chloro-2-hydroxypropyl)trimethyl ammonium chloride and/or 1-propanaminium, N,N′-(oxydi-2,1-ethanediyl)bis[3-chloro-2-hydroxy-N,N-dimethyl dichloride. 
     
     
         5 . The cationic cellulosic fiber of  claim 1 , which is prepared by a process comprising the steps of:
 immersing an untreated cellulosic fiber into a cationic treatment solution through a yarn treatment slasher machine to form a saturated cellulosic fiber, wherein the cationic treatment solution comprises a cationic agent and an alkali;   padding the saturated cellulosic fiber though a horizontal squeeze roll to a liquor pick-up of up to about 100% of the weight of the untreated cellulosic fiber to form a padded cellulosic fiber;   heating the padded cellulosic fiber to form a fixated cationic cellulosic fiber; and   processing the fixated cationic cellulosic fiber to form the cationic cellulosic fiber.   
     
     
         6 . The cationic cellulosic fiber of  claim 5 , wherein the ratio of cationic agent to alkali in the cationic treatment solution is in the range of about 10:1 to about 1:10. 
     
     
         7 . The cationic cellulosic fiber of  claim 5 , wherein the ratio of cationic treatment solution to untreated cellulosic fiber is about 1:1. 
     
     
         8 . The cationic cellulosic fiber of  claim 5 , wherein the heating is performed by conveying the padded cellulosic fiber through a heating means selected from the group consisting of a heating bath, a steam chamber, a dry can column, and a hot air chamber. 
     
     
         9 . A cationic fabric comprising the cationic cellulosic fiber of  claim 1 . 
     
     
         10 . The cationic fabric of  claim 9 , which is substantially colorless. 
     
     
         11 . The cationic fabric of  claim 9 , prepared by a process comprising the steps of:
 providing the cationic cellulosic fiber as a warp yarn for weaving; and   weaving the cationic cellulosic fiber with an untreated weft yarn to yield a cationic fabric.   
     
     
         12 . A garment comprising the cationic fabric of  claim 9 . 
     
     
         13 . The garment of  claim 12 , which is substantially colorless. 
     
     
         14 . The garment of  claim 12 , which is a dyed garment. 
     
     
         15 . The garment of  claim 12 , which has a denim-like appearance. 
     
     
         16 . The garment of  claim 12 , which is a dyed garment, prepared by a process comprising the steps of:
 providing the cationic fabric;   shaping the cationic fabric into a substantially colorless garment;   immersing the substantially colorless garment in a dye bath solution comprising water and a wetting agent to form a pre-treated garment; and   reacting the pre-treated garment with an anionic dye, wherein the reacting involves gradually adding the anionic dye to the dye bath solution containing the pre-treated garment, wherein the dye bath solution is substantially free of salt and alkaline content.   
     
     
         17 . The garment of  claim 16 , wherein the anionic dye is a direct dye, a reactive dye or an acid dye. 
     
     
         18 . The garment of  claim 16 , wherein the ratio of weight of the substantially colorless garment to weight of the dye bath solution is in the range of about 1:4 to about 1:50. 
     
     
         19 . The garment of  claim 16 , wherein the dye bath solution is substantially free of sodium chloride and sodium sulphate. 
     
     
         20 . A method of recycling the cationic fabric of  claim 9  to form a regenerated cationic cellulosic fiber, comprising:
 cutting the cationic fabric to form a plurality of cellulosic fiber fragments; and 
 reacting the plurality of cellulosic fiber fragments with a cationic treatment solution comprising a cationic agent and an alkali. 
 
     
     
         21 . A method of producing a garment from a ring dyed core yarn, comprising:
 preparing a cationic cellulosic fiber comprising the steps of:
 treating an outer layer comprising a plurality of covalently attached cationic moieties, wherein the cationic moieties are derived from a quaternary ammonium salt; and 
 leaving an inner layer that is substantially free of cationic charge after the treating step; 
   weaving the cationic cellulosic fiber into an undyed cationic fabric;   shaping the undyed cationic fabric into:
 a substantially colorless garment; and 
 cut-and-sew waste; 
   dyeing the substantially colorless garment with an anionic dye; and   reprocessing the cut-and-sew waste into an undyed cationic yarn.   
     
     
         22 . The method of  claim 21 , wherein the undyed cationic yarn is weaved into the undyed cationic fabric. 
     
     
         23 . The method of  claim 21 , wherein the reprocessing step comprises cutting and grinding the cut-and-sew waste. 
     
     
         24 . A cationic cellulosic yarn comprising:
 an outer layer comprising a plurality of covalently attached cationic moieties; and   an inner layer that is substantially free of cationic charge,   wherein the plurality of covalently attached cationic moieties gradually decreases through a thickness of the outer layer toward the inner layer, and wherein the cationic moieties are derived from a quaternary ammonium salt.   
     
     
         25 . An anionic dyed cellulosic yarn comprising:
 a surface layer of the yarn absorbing the largest proportion of the anionic dye;   an inner core of the yarn absorbing none of the anionic dye; and   a gradation layer of the yarn between the surface layer and the inner core, wherein the gradation layer absorbs a varying amount of the anionic dye depending on the distance from the surface layer.   
     
     
         26 . The anionic dyed cellulosic yarn of  claim 25 , wherein the amount of anionic dye absorbed by the gradation layer is at a maximum closest to the surface layer and a minimum closest to the inner core. 
     
     
         27 . The anionic dyed cellulosic yarn of  claim 25 , wherein the anionic dye is a direct dye, a reactive dye or an acid dye. 
     
     
         28 . The anionic dyed cellulosic yarn of  claim 25 , that is substantially free of indigo dye.