Modified kraft fibers

Abstract

A method of producing a modified pulp comprising treating wood chips in an extraction process to remove hemicellose to form treated wood chips; and subjecting said treated wood chips to chemical or semichemical pulping to form a modified Kraft pulp wherein the amount of hemicellulose contained in the modified Kraft pulp is from about 5 to about 10% by dry weight of the modified pulp.

What is claimed is: 
     
         1 . A method of producing a modified bleached Kraft pulp comprising:
 treating wood chips with an acidic solution in an extraction process with steam, a liquid comprising water or a combination thereof to remove 5% to 20% hemicellulose to form treated wood chips having a pH equal or less than 5.0;   subjecting the treated wood chips to chemical or semichemical pulping to form a modified Kraft pulp wherein the amount of hemicellulose contained in the modified Kraft pulp is from about 3 to about 15% by oven dried weight of the modified pulp;   directly after the subjecting the treated wood chips step, bleaching the modified Kraft pulp to form a modified bleached Kraft pulp.   
     
     
         2 . The method of  claim 1  further comprising a washing step. 
     
     
         3 . The method of  claim 1  further comprising a refining step. 
     
     
         4 . The method of  claim 1  wherein the wood chips are extracted at temperatures ranging from 140 ° C. to 160 ° C. 
     
     
         5 . The method of  claim 1  wherein the wood chips are treated at treatment time ranging from 30 minutes to 240 minutes. 
     
     
         6 . The method of  claim 1  wherein the removal of 5% to 20% hemicelluloses at the extracted temperature of 140 ° C. will take from about 60 minutes to 150 minutes. 
     
     
         7 . The method of  claim 1  wherein the modified Kraft pulp includes enhanced properties define by higher bulk, higher brightness, better drainage and dewatering or drying or a combination. 
     
     
         8 . The method of  claim 1  wherein the step of treating wood chips is producing a modified Kraft pulp having at least about 1% by weight less hemicelluloses the same pulp when un-modified. 
     
     
         9 . The method of  claim 1  wherein the step of treating wood chips is producing a modified Kraft pulp having from about 2% to about 8% less hemicelluloses than the same pulp when un-modified. 
     
     
         10 . The method of  claim 1  wherein the acidic pH is from about 2 to about 4. 
     
     
         11 . The method of  claim 1  wherein the modified pulp exhibits water retention of from about 0.2 g/g to about 0.5 g/g less than that of the same or substantially the same unmodified pulp. 
     
     
         12 . The method of  claim 1  wherein the modified pulp exhibits freeness of from about 25 to about 200 CSF units greater than that of the same or substantially same un-modified pulp. 
     
     
         13 . The method of  claim 1  wherein prior to or during the treating step, a peroxide is added in the treatment. 
     
     
         14 . The method of  claim 13  wherein additional peroxide is added to an extracted hemicelluloses portion after the treating step. 
     
     
         15 . The method of  claim 13  wherein the peroxide is at least one member selected from group consisting of hydrogen peroxide, perborate, per carbonate, persulfate, peroxymonosulfuric (or Oxone) or peracetic acid. 
     
     
         16 . A method of producing a modified bleached Kraft pulp comprising:
 treating wood chips with an acidic solution in an extraction process with steam, a liquid comprising water or a combination thereof to remove 5% to 20% hemicellulose to form treated wood chips having a pH equal or less than 5.0;   subjecting the treated wood chips to chemical or semichemical pulping to form a modified Kraft pulp wherein the amount of hemicellulose contained in the modified Kraft pulp is from about 3 to about 15% by oven dried weight of the modified pulp;   directly after the subjecting step, washing the modified pulp to remove the Kraft liquor therefrom; and   directly after the washing step, bleaching the modified Kraft pulp to form a modified bleached Kraft pulp.   
     
     
         17 . The method of  claim 14  further comprising a refining step after the bleaching step. 
     
     
         18 . The method of  claim 14  wherein the wood chips are extracted at temperature ranging from 140 ° C. to 160 ° C. 
     
     
         19 . The method of  claim 1  wherein the removal of 5% to 20% hemicelluloses at the extracted temperature of 140 ° C. will take from about 60 minutes to 150 minutes.