Paper product and method of making

Abstract

Paper having improved curl and cockle properties for water based, ink jet printing applications and a method of producing them. The paper contains at least 50 pounds per ton of a mono alkali metal salt of citric acid. The paper has a maximum Cockle Value of 0.25. It also contain a hexasulfonated optical brightener. The paper is also water fast and can be preprinted with offset printing inks. A method for making the paper.

1 . Uncoated printing paper comprising cellulosic fibers, hexasulfonate optical brightener and at least 50 pounds per ton of said papermaking fibers of a mono alkali metal salt of citric acid.  
     
     
         2 . The printing paper of  claim 1  in which the mono alkali metal salt of citric acid is a mono sodium citrate.  
     
     
         3 . The printing paper of  claim 1  in which the mono alkali metal salt of citric acid is a mono potassium citrate.  
     
     
         4 . The printing paper of  claim 1  in which the salt of citric acid is present in the range of 50 to 300 pounds per ton of paper.  
     
     
         5 . The printing paper of  claim 4  in which the mono alkali metal salt of citric acid is a mono sodium citrate.  
     
     
         6 . The printing paper of  claim 4  in which the mono alkali metal salt of citric acid is a mono potassium citrate.  
     
     
         7 . The printing paper of  claim 1  in which the mono alkali metal salt of citric acid is present in the range of 75 to 250 pounds per ton of paper.  
     
     
         8 . The printing paper of  claim 7  in which the mono alkali metal salt of citric acid is a mono sodium citrate.  
     
     
         9 . The printing paper of  claim 7  in which the mono alkali metal salt of citric acid is a mono potassium citrate.  
     
     
         10 . The printing paper of  claim 1  in which said paper has a maximum Cockle Value of 0.25.  
     
     
         11 . The printing paper of  claim 1  in which said paper is water fast.  
     
     
         12 . The printing paper of  claim 1  further comprising starch, ethylated starch or polyvinyl alcohol.  
     
     
         13 . Uncoated printing paper comprising cellulosic fibers, optical brightener and at least 50 pounds per ton of said papermaking fibers of a mono potassium salt of citric acid, the paper having a maximum Cockle Value of 0.25