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.

What is claimed: 
     
         1 . A method for modulating the morphology of cellulosic fibers comprising the steps of
 subjecting the fibers to a metal ion-activated peroxide treatment carried out at a pH of between about 1 and about 9 and   subjecting the treated fibers to a refining treatment.   
     
     
         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 ion. 
     
     
         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 . A softwood pulp having a modified morphology, leading to paper making properties substantially functionally equivalent to hardwood pulp papermaking properties. 
     
     
         11 . The softwood pulp of  claim 10  wherein the fibers of said softwood pulp, after treatment, exhibit a substantially shorter fiber length and distribution, and enhanced fiber collapsibility, than prior to treatment. 
     
     
         12 . The softwood pulp of  claim 9  wherein said pulp is oxidatively degraded relative to untreated softwood pulp. 
     
     
         13 . The softwood pulp of  claim 10  wherein the pulp exhibits a Canadian Standard Freeness of between about 115 and about 590. 
     
     
         14 . The softwood pulp of  claim 13  wherein the pulp exhibits a Kajaani average fiber length of between about 1.0 and 1.9 mm 
     
     
         15 . A pulp comprising between about 50% and 90% hardwood pulp and the remainder being softwood pulp which has been subjected to a metal ion-activated peroxide treatment carried out at a pH of between about 2 and about 9 and a refining treatment. 
     
     
         16 . The pulp of  claim 15  wherein said metal ion is a transitional metal. 
     
     
         17 . The pulp of  claim 15  wherein said metal ion is iron and said pH is between about 3 and about 7. 
     
     
         18 . The pulp of  claim 15  wherein said pulp is substantially functionally equivalent to a hardwood pulp as respects the usefulness of the pulp in papermaking. 
     
     
         19 . The softwood pulp of  claim 11  wherein the pulp is used to manufacture a paper web material.