Enhanced bulk and high strength paper

Abstract

Disclosed herein are systems and methods for attaching particulate additives to a population of cellulose fibers dispersed in an aqueous solution. The cellulose fibers are treated with an activator that forms complexes with them. The particulate additive is attached to a tether that is capable of interacting with the activator, thereby forming a tether-bearing particulate additive. The tether-bearing particulate additive can be added to the activated suspension of cellulose fibers. The resulting interaction between the tether and the activator forms durable complexes that attach the particulate additive to the cellulose fibers. Using these systems and methods, useful additives like starches can be attached to cellulose fibers, imparting advantageous properties such as increased strength to paper products formed thereby. These systems and methods are particularly useful for papermaking involving virgin pulp fibers, recycled fibers, or any combination thereof.

1 . A method of increasing the bulk of a paper product formed from a pulp slurry comprising cellulose fibers, comprising:
 providing a first population of cellulose fibers comprising unrefined softwood fibers,   forming a first slurry comprising the first population,   adding an activator polymer to the first slurry, forming complexes between the activator polymer and the cellulose fibers,   providing a second population of cellulose fibers comprising hardwood fibers,   forming a second slurry comprising the second population,   preparing tether-bearing starch granules, wherein the tether-bearing starch granules comprise a tether polymer capable of interacting with the activator polymer,   combining the tether-bearing starch granules with the second slurry whereby the tether-bearing starch granules attach to the hardwood fibers, and   adding the second slurry to the first slurry to form a pulp slurry, whereby the tether-bearing starch granules attach the hardwood fibers to the softwood fibers in the pulp slurry, thereby improving a measure of bulk of a paper product formed from the pulp slurry.   
     
     
         2 . The method of  claim 1 , wherein the bulk is increased without a loss of strength. 
     
     
         3 . A method of increasing the bulk of a paper product formed from a pulp slurry comprising cellulose fibers, comprising:
 providing a cellulose fiber mixture,   forming a slurry comprising the cellulose fiber mixture,   adding an activator polymer to the slurry to form an activated mixture comprising activated cellulose fibers,   preparing tether-bearing starch granules, wherein the tether-bearing starch granules comprise a tether polymer capable of interacting with the activator polymer,   combining the tether-bearing starch granules with the activated fiber mixture, whereby the tether-bearing starch granules affix the activated cellulose fibers to each other, thereby increasing the bulk of the paper product formed therefrom.   
     
     
         4 . The method of  claim 3 , wherein the cellulose fiber mixture comprises recycled fibers. 
     
     
         5 . The method of  claim 3 , wherein the cellulose fiber mixture comprises hardwood and softwood fibers. 
     
     
         6 . The method of  claim 4 , wherein the cellulose fiber mixture comprises refined and unrefined fibers. 
     
     
         7 . The method of  claim 5 , wherein the cellulose fiber mixture comprises about 40% to about 80% of hardwood fibers. 
     
     
         8 . The method of  claim 5 , wherein the cellulose fiber mixture comprises from about 60% to about 80% hardwood fibers. 
     
     
         9 . The method of  claim 5 , wherein the cellulose fiber mixture comprises from about 65% to about 75% hardwood fibers. 
     
     
         10 . A paper product formed according to the method of  claim 1 . 
     
     
         11 . A papermaking precursor comprising a population of cellulose fibers in an aqueous solution wherein:
 the population of cellulose fibers is dispersed in the aqueous solution and   wherein the cellulose fibers are complexed with an activator, and   wherein the aqueous solution further comprises a tether-bearing particulate additive,   wherein the tether-bearing particulate additive attaches to the population of cellulose fibers by an interaction between the activator and the tether.   
     
     
         12 . The precursor of  claim 11 , wherein the additive is an organic additive. 
     
     
         13 . The precursor of  claim 12 , wherein the organic additive comprises a starch. 
     
     
         14 . The precursor of  claim 13 , wherein the starch comprises a cationic starch. 
     
     
         15 . The precursor of  claim 13 , wherein the starch comprises a hydrophobic starch. 
     
     
         16 . The precursor of  claim 11 , wherein the additive is an inorganic additive. 
     
     
         17 . A paper product formed by subjecting the papermaking precursor of  claim 11  to a papermaking process comprising drying. 
     
     
         18 . A system for papermaking, comprising:
 a first set of processing stations, wherein a papermaking precursor is formed by combining a population of cellulose fibers dispersed in an aqueous solution and complexed with an activator, and a tether-bearing particulate additive, and wherein the addition of the tether-bearing particulate additive attaches the additive to the population of cellulose fibers by the interaction of the activator and the tether; and   a second set of processing stations.   
     
     
         19 . The system of  claim 18 , wherein the additive is an organic additive. 
     
     
         20 . The system of  claim 19 , wherein the organic additive comprises a starch. 
     
     
         21 . The system of  claim 20 , wherein the starch comprises a cationic starch. 
     
     
         22 . The system of  claim 20 , wherein the starch comprises a hydrophobic starch. 
     
     
         23 . The system of  claim 18 , wherein the additive is an inorganic additive.