Anionic-cationic polymer blend for surface size
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.