Pulping processes

Abstract

A pulping process comprises using a high concentration of anthraquinone (AQ). The pulping process is capable of providing a pulp having low Kappa number with unexpectedly high strength. The pulping process can use wood or non-wood fibers (e.g., bagasse and corn stover) to provide pulp having good papermaking quality. The method for pulping a fiber comprising cooking a first mixture comprising the fibers, water, an alkali, and a delignification selectivity enhancing chemical for a cooking time and at a cooking condition sufficient to form a first pulp having a desired Kappa number of about 15 or less, and strength parameters that are sufficient for papermaking, where the starting material prior to cooking has a Kappa number of 60 or greater.

1 . A method for pulping a fiber comprising:
 providing a first mixture comprising the reaction products of:
 a fiber from a non-wood fiber source, 
 water, 
 anthraquinone, or derivative thereof, having concentration of about 0.1% by weight or greater of the dry fiber, and 
 an alkali, 
 wherein the first mixture has a liquid to dry fiber ratio from about 4 to about 10, and an initial Kappa number of about 60 or greater; and 
   reacting the first mixture for a cooking time and at a cooking condition sufficient to form a second mixture having a Kappa number of about 20 or less.   
     
     
         2 . The method of  claim 1 , wherein the second mixture has a tensile of at least about 5.50 km, and/or a burst index of at least about 3.00 kPa·m 2 /g. 
     
     
         3 . The method of  claim 1 , wherein the first mixture comprises the reaction products of about 0.2% by weight or greater of anthraquinone or derivative thereof. 
     
     
         4 . The method of  claim 1 , wherein the cooking condition and cooking time provides an H-factor of about 200 or higher. 
     
     
         5 . The method of  claim 1 , wherein the second mixture has a Kappa number of about 19 or less. 
     
     
         6 . The method of  claim 1 , wherein the second mixture has a Kappa number of about 18 or less. 
     
     
         7 . The method of  claim 1 , wherein the second mixture has a Kappa number of about 15 or less. 
     
     
         8 . The method of  claim 1 , wherein the non-wood fiber source comprises agricultural renewable fiber. 
     
     
         9 . The method of  claim 8 , wherein the agricultural renewable fiber comprises bagasse, corn stover, wheat straw, cereal straws, rice straw, soy residuals, coconut tissues, cotton stalks, palm baskets, kenaf, industrial hemp, seed flax straw, textile flax straw, sisal, hesperaloe, rye grass, or combinations thereof. 
     
     
         10 . The method of  claim 1 , wherein the second mixture has a Kappa number of about 5 or less and further comprising the step of bleaching the second mixture to form a third mixture having an ISO brightness of about 80% or higher. 
     
     
         11 . The method of  claim 10 , wherein the step of bleaching comprises a chlorine free bleaching or elemental chlorine free bleaching. 
     
     
         12 . The method of  claim 11 , wherein the third mixture has an ISO brightness of about 88% or higher. 
     
     
         13 . A method for pulping a fiber comprising:
 providing a first mixture comprising the reaction products of:
 a fiber from a wood fiber source, 
 water, 
 anthraquinone or derivative thereof, having a concentration of about 0.1% by weight or greater of the dry fiber, and 
 an alkali, 
 wherein the first mixture has a liquid to dry fiber ratio from about 4 to about 10, and an initial Kappa number of about 60 or greater; and 
   reacting the first mixture for a cooking time and at a cooking condition sufficient to form a second mixture having a Kappa number of about 20 or less.   
     
     
         14 . The method of  claim 13 , wherein the cooking time and the cooking condition provides an H-factor of about 2000 or higher for the cooking reaction. 
     
     
         15 . The method of  claim 14 , wherein the second mixture has a Kappa number of about 10 or less. 
     
     
         16 . The method of  claim 15 , wherein the second mixture has a Kappa number of about 5 or less and further comprising the step of bleaching the second mixture to a third mixture having ISO brightness of about 80% or higher. 
     
     
         17 . A pulp composition made according to the method of  claim 1 . 
     
     
         18 . A pulp composition made according to the method of  claim 2 . 
     
     
         19 . A pulp composition made according to the method of  claim 13 . 
     
     
         20 . A pulp composition made according to the method of  claim 14 .