Degumming and scouring of bast material for production of textile and pulp-quality fiber

Abstract

A method for degumming bast fibers comprising soaking a source of bast fiber in a saline solution. The source of bast fiber may be soaked in a saline solution having a concentration ranging between less than 1 part per thousand to about 200 parts per thousand. The saline concentration may vary as the source of bast fiber is soaking, or by alternating bast fiber between aqueous solutions of differing ionic concentrations. In one embodiment, the source of bast fiber is soaked in seawater, wherein the saline concentration varies by alternating the salinity using a tide. The source of bast fiber may be hemp.

What is claimed is: 
     
         1 . A method for degumming bast fibers comprising immersing a source of bast fibers in an aqueous solution and varying the ionic concentration of the aqueous solution in which the source of bast fibers is immersed so that the varying ionic concentration of the solution imposes varying interstitial pressure within the source of bast fibers to aid in release of gum from cellulose fibers in the source of bast fibers. 
     
     
         2 . The method as claimed in  claim 1  wherein varying the ionic concentration of the solution has an effect selected from the group consisting of delivering reagent to the source of bast fibers, flushing gum and reacted byproducts from the bast fibers, imparting structural stress on the source of bast fibers, increasing surface area of gum as a reactive substrate, separating the bast fibers freed of gum, and more than one of them. 
     
     
         3 . The method as claimed in  claim 1  wherein the source of bast fibers soaks in an ionic solution without electrolysis of the ionic solution. 
     
     
         4 . The method of  claim 1 , wherein the ionic solution is a saline solution having a concentration ranging from less than 1 part per thousand to about 200 parts per thousand. 
     
     
         5 . The method of  claim 4  including varying the ion concentration of the aqueous soaking solution in which the source of bast fiber is immersed. 
     
     
         6 . The method of  claim 1 , wherein immersing a source of bast fiber comprises soaking the source of bast fiber in seawater. 
     
     
         7 . The method of  claim 1 , wherein immersing a source of bast fiber comprises soaking the source of bast fiber in brackish water. 
     
     
         8 . The method of  claim 5 , wherein varying the concentration of the aqueous solution comprises exposing the source of bast fiber to water with salinity that varies with time. 
     
     
         9 . The method of  claim 1  including soaking the source of bast fiber in a sulfur solution to sulfonate lignin for removal from bast fiber in the source of bast fiber. 
     
     
         10 . The method of  claim 1  including soaking the source of bast fiber in an oxidizing solution to remove lignin, pectin and hemicellulose from bast fiber in the source of bast fiber. 
     
     
         11 . The method of  claim 1  including rinsing the source of bast fiber with water to further remove lignin, pectin and hemicellulose from the bast fiber in the source of bast fiber. 
     
     
         12 . The method of  claim 1  including rinsing the source of bast fiber with detergent and water to further remove lignin, pectin and hemicellulose from the bast fiber in the source of bast fiber. 
     
     
         13 . The method of  claim 1  wherein the source of bast fiber is hemp. 
     
     
         14 . A method for removing lignin, pectin and hemicellulose from cellulosic fibers in a hemp plant comprising:
 soaking the hemp plant in a saline solution;   soaking the hemp plant in a sulfur solution to sulfonate lignin for removal from the hemp plant; and   rinsing the hemp plant with aqueous solution to further remove lignin, pectin and hemicellulose and their partially oxidized intermediates from the cellulosic fibers in the hemp plant.   
     
     
         15 . The method of  claim 14  including soaking the hemp plant in an oxidizing solution to remove lignin, pectin and hemicellulose from the cellulosic fiber. 
     
     
         16 . The method of  claim 15 , wherein soaking the hemp plant in an oxidizing solution comprises soaking the hemp plant in a hydrogen peroxide solution. 
     
     
         17 . The method of  claim 16 , including generating hydrogen peroxide as the oxidizing solution with electrolysis. 
     
     
         18 . The method of  claim 15 , wherein soaking hemp plant in an oxidizing solution comprises soaking the hemp plant in the oxidizing solution at a pH between about 6 to about 12 and at a temperature below a boiling point of the oxidizing solution. 
     
     
         19 . The method of  claim 14 , wherein soaking the hemp plant in a sulfur solution comprises soaking the hemp plant in the sulfate solution at a pH between about 6 to about 12 and at a temperature between about 20° C. to about 90° C. 
     
     
         20 . The method of  claim 14 , wherein soaking the hemp plant in a saline solution comprises soaking the hemp plant in tidally flushed water so that the salinity of the solution proximate to the hemp plant varies with tidal fluctuations. 
     
     
         21 . A bast fiber having a green color, the bast fiber being sufficiently free of lignin, pectin and hemicellulose that the fiber can be processed in conventional textile machinery. 
     
     
         22 . A bast fiber as claimed in  claim 21  wherein the bast fiber has a green color imparted to the bast fiber by chlorophyll. 
     
     
         23 . A bast fiber as claimed in  claim 21  wherein processing in conventional textile machinery is selected from the group consisting of spinning, braiding, felting, making nonwovens such as by needle-punching, and more than one of them. 
     
     
         24 . A bast fiber as claimed in  claim 21  wherein the bast fiber is hemp. 
     
     
         25 . A bast fiber as claimed in  claim 21  wherein the green color of the bast fiber is extractable and has an absorption spectrum indicating the presence of chlorophyll in the extract.