Treated kraft pulp compositions and methods of making the same

Abstract

Compositions including treated Kraft pulp, useful for making rayon fibers, having a lower degree of polymerization, a high R18, a low hemicellulose content, and high reactivity, are described. Methods of making the compositions are also described.

What is claimed is: 
     
         1 . A treated Kraft pulp, comprising:
 a hemicellulose content of 5% or more;   a R18 value of 88% or more; and   at least one reactivity value selected from:   a standard reactivity of 3.5 mL or more,   a modified reactivity of 30 mL or more,   a gamma number of 60% or less,   a filter value Kr of 10,000 or less,   a SEM fiber segment count of 11 or less per 100 µm 2  of a filter when the pulp is subjected to a modified reactivity test, and a crystallite cross-section of less than 20.6 nm 2 ;   wherein the treated pulp has less than 8% by weight of cellulose II as determined by x-ray crystallography; and   wherein the treated Kraft pulp is treated chemical wood pulp.   
     
     
         2 . The treated pulp of  claim 1 , wherein the hemicellulose content is greater than 7%. 
     
     
         3 . The treated pulp of  claim 1 , wherein the R18 value is from 88% to 92%. 
     
     
         4 . The treated pulp of  claim 1 , wherein the treated pulp further comprises one or more of a pentosan content of from 4.6% to 9%, a xylan content of 4% to 8%, and a mannan content of 3% to 8%. 
     
     
         5 . The treated pulp of  claim 1 , wherein the treated pulp comprises a standard reactivity of 5 mL or more. 
     
     
         6 . The treated pulp of  claim 1 , wherein the treated pulp comprises a modified reactivity of 50 mL or more. 
     
     
         7 . The treated pulp of  claim 1 , wherein the treated pulp comprises a filter value Kr of 8,000 or less. 
     
     
         8 . The treated pulp of  claim 1 , wherein the treated pulp further comprises a carboxyl content of less than 3.6 meq/100 g. 
     
     
         9 . The treated pulp of  claim 1 , wherein the treated pulp further has an ASTM degree of polymerization of from 600 to 900. 
     
     
         10 . The treated pulp of  claim 1 , wherein the treated pulp further has a copper number of from 0.3 to 1.2. 
     
     
         11 . The treated pulp of  claim 1 , wherein the treated pulp has 0% cellulose II as determined by x-ray crystallography. 
     
     
         12 . The treated pulp of  claim 1 , wherein the treated pulp has an ageing time of 50 hours or less to reach a target Cuox DP of 340. 
     
     
         13 . A pulp blend comprising:
 a treated pulp according to  claim 1 ;   a dissolving pulp having a R18 of greater than 92%; and   a total xylan and mannan content of 6% or more;   wherein the blend comprises at least 20% by weight of the treated pulp.   
     
     
         14 . The blend of  claim 13 , further comprising a surfactant. 
     
     
         15 . (canceled) 
     
     
         16 . The blend of  claim 13 , wherein the blend further comprises a filter value Kr of 15,000 or less. 
     
     
         17 . The blend of  claim 13 , wherein the blend further comprises a gamma number of 45.1% or more. 
     
     
         18 . The blend of  claim 13 , wherein the blend has an ageing time of 50 hours or less to reach a target Cuox DP of 340. 
     
     
         19 - 20 . (canceled) 
     
     
         21 . The treated pulp of  claim 1 , wherein the treated pulp further has a copper number of from 0.2 to 1.6. 
     
     
         22 . A treated Kraft pulp, comprising:
 a hemicellulose content of 5% or more; a R18 value of 88% or more; and a gamma number of 60% or less;   wherein the treated pulp has less than 8% by weight of cellulose II as determined by x-ray crystallography; and   wherein the treated Kraft pulp is treated chemical wood pulp.