Anionic-cationic polymer blend for surface size

Abstract

A composition for surface sizing and strengthening of paper and other cellulosic products and the related sizing method and resulting sized product, wherein the composition is an aqueous mixture of a film-forming binder, such as starch and an anionic polymer and a cationic polymer.

1 . A method of sizing a cellulosic web for improving surface size and surface strength comprising applying to a surface of the cellulosic web an aqueous sizing mixture of a film-forming binder, a cationic polymer and an anionic polymer, wherein the film-forming binder is a starch, wherein the cationic polymer is a polyamidoamine-epichlorohydrin resin and wherein the anionic polymer is a hydrolyzed copolymer of styrene-maleic anhydride.  
     
     
         2 . The method of  claim 1  wherein the hydrolyzed copolymer of styrene-maleic anhydride has a copolymer of styrene-acrylic ester dispersed therein.  
     
     
         3 . The method of  claim 2  wherein said hydrolyzed copolymer of styrene-maleic anhydride is prepared by forming an ammonium salt of said styrene-maleic anhydride copolymer.  
     
     
         4 . The method of  claim 3  wherein said hydrolyzed copolymer of styrene-maleic anhydride having a copolymer of styrene-acrylic ester dispersed therein is NovaCote PS2.  
     
     
         5 . A sized cellulosic web made by the method of  claim 1 .  
     
     
         6 . A sized cellulosic web made by the method of  claim 2 .  
     
     
         7 . A sized cellulosic web made by the method of  claim 3 .  
     
     
         8 . A sized cellulosic web made by the method of  claim 4.