Chemical activation and refining of southern pine kraft fibers

Abstract

A method for alteration of the morphology of cellulose fibers, particularly softwood fibers, by (a) subjecting the fibers to a metal ion-activated peroxide treatment carried out at a pH of between about 1 and about 9, preferably between 3 and 7, and (b) subjecting the treated fibers to a refining treatment thereby converts SW fibers to HW-like fibers in many respects. The metal ion-activated peroxide treatment has been noted to act on pulp cellulose and hemi-cellulose, causing oxidation and oxidative degradation of cellulose fibers. The chemical treatment of the pulp, taken alone, is not sufficient to attain the desired modification of the morphology of the fibers, however, subsequent refining or like mechanical treatment of the chemically-treated fibers to achieve a given degree of refinement of the fibers requires dramatically less refining energy to achieve a desired end point of refinement and to impart other desirable properties to the pulp. A pulp of modified SW fibers and a mixture of HW fibers and modified HW fibers are disclosed.

1 . A method for modulating the morphology of cellulosic fibers comprising the step of: 
 subjecting the fibers to a metal ion-activated peroxide treatment carried out at a pH from about 1 to about 9.    
     
     
         2 . The method of  claim 1  wherein said metal ion is a transitional metal ion.  
     
     
         3 . The method of  claim 1  wherein said metal ion is iron.  
     
     
         4 . The method of  claim 1  wherein said pH is between about 3 and about 7.  
     
     
         5 . The method of  claim 1  wherein the fibers are subjected to the solution at temperatures between about 40 degrees C. to about 120 degrees C.  
     
     
         6 . The method of  claim 1  wherein the fibers are subjected to the solution for between about 10 minutes to about 10 hour.  
     
     
         7 . The method of  claim 1  wherein said peroxide is present with said solution at a concentration of between about 0.2% and about 5% based on pulp.  
     
     
         8 . The method of  claim 1  wherein said metal ion is present in said solution at a concentration of between about 0.002% and about 0.1% on pulp.  
     
     
         9 . The method of  claim 1  wherein said pulp is subjected to said solution for a time sufficient to substantially act on at least the cellulose and hemi-cellulose of the pulp, causing oxidation and oxidative degradation of cellulose fibers.  
     
     
         10 . (canceled)  
     
     
         11 . A cellulose fiber having modified morphology wherein the cellulose fiber after treatment, exhibits a substantially shorter fiber length and distribution, and enhanced fiber collapsibility, than prior to treatment.  
     
     
         12 . The cellulose fiber of  claim 11  wherein said fiber is oxidatively degraded relative to untreated softwood pulp fiber.  
     
     
         13 . The cellulose fiber of  claim 11  wherein the fiber exhibits a Canadian Standard Freeness of between about 115 and about 590.  
     
     
         14 . The cellulose fiber of  claim 13  wherein the fiber exhibits a Kajaani average fiber length of between about 1.0 and 1.9 mm.  
     
     
         15 . (canceled)  
     
     
         16 . (canceled)  
     
     
         17 . (canceled)  
     
     
         18 . (canceled)  
     
     
         19 . (canceled)  
     
     
         20 . The cellulose fiber of  claim 11  wherein said cellulosic fiber is a pulp fiber.  
     
     
         21 . The cellulose fiber of  claim 20  wherein said pulp fiber is softwood pulp fiber.  
     
     
         22 . The cellulose fiber of  claim 1  wherein said cellulosic fiber is a pulp fiber.  
     
     
         23 . The cellulose fiber of  claim 22  wherein said pulp fiber is softwood pulp fiber.  
     
     
         24 . A personal hygiene article for absorbing fluids, the article comprising: 
 at least one fluid permeable top sheet layer and at least one substantially fluid impermeable back sheet layer; and    an absorbent sub-layer material interposed between the top sheet layer and the back sheet layer, the sub-layer material comprising a cellulosic fiber having modified morphology in accordance to  claim 11.