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 composition for improving surface size and surface strength for cellulosic products comprising an aqueous sizing mixture of a film-forming binder, an anionic polymer and a cationic polymer.  
     
     
         2 . The composition of  claim 1 , wherein the film-forming binder is a starch.  
     
     
         3 . The composition of  claim 2  wherein the cationic polymer and starch are provided using a cationic polymer-grafted onto said starch.  
     
     
         4 . The composition of  claim 2  wherein the anionic polymer and starch are provided using an anionic polymer-grafted onto said starch.  
     
     
         5 . The composition of  claim 2  wherein the anionic polymer is an alkali soluble, acid-containing copolymer.  
     
     
         6 . The composition of  claim 5  wherein the anionic polymer is selected from the group consisting of a hydrolyzed copolymer of styrene-maleic anhydride, or one of its salts; a copolymer of styrene-maleic acid, or one of its salts; a styrene-acrylic acid copolymer, or one of its salts, a styrene-methacrylic acid copolymer, or one of its salts, a styrene-fumaric acid copolymer, or one of its salts, a styrene-acrylonitrile-acrylic acid copolymer, or one of its salts, a styrene-butyl acrylate-acrylic acid copolymer, or one of its salts; a copolymer of styrene-acrylic ester dispersed in a copolymer of styrene-maleic acid, or one of its salts, and mixtures thereof.  
     
     
         7 . The composition of  claim 5  wherein the cationic polymer is selected from the group consisting of a polyamine; a polyethylene imine; a styrene-maleic anhydride copolymer imide quaternary ammonium salt; a polyamidoamine-epichlorohydrin resin; a dialkylamine-epichlorohydrin resin; a homo- or copolymer of diallyldimethyl-ammonium chloride; a homo- or copolymer of a vinyl amine; a homo- or copolymer of a (meth)acrylamide; a homo- or copolymer of a (meth)acrylate, and corresponding acid addition salts and quaternary ammonium salts thereof.  
     
     
         8 . The composition of  claim 1  comprising a mixture of starch grafted with a copolymer of diallyldimethylammonium chloride-acrylamide and an alkali soluble, acid containing copolymer.  
     
     
         9 . The composition of  claim 2  comprising an anionic polymer latex having sulfonic or carboxylic moieties and a polyamidoamine-epichlorohydrin resin.  
     
     
         10 . The composition of  claim 2  comprising a copolymer of styrene-acrylic ester dispersed in a copolymer of styrene-maleic acid, or one of its salts and a polyamidoamine-epichlorohydrin resin.  
     
     
         11 . The composition of  claim 8  wherein the alkali soluble, acid containing copolymer is selected from the group consisting of a hydrolyzed copolymer of styrene-maleic anhydride, or one of its salts; a copolymer of styrene-maleic acid, or one of its salts; a styrene-acrylic acid copolymer, or one of its salts, a styrene-methacrylic acid copolymer, or one of its salts, a styrene-acrylonitrile-acrylic acid copolymer, or one of its salts, a styrene-butyl acrylate-acrylic acid copolymer, or one of its salts and mixtures thereof.  
     
     
         12 . A composition for improving surface size and surface strength for cellulosic products comprising an aqueous sizing mixture of a film-forming binder, an anionic polymer and a cationic polymer, wherein the film-forming binder is a starch, wherein the anionic polymer is selected from the group consisting of a hydrolyzed copolymer of styrene-maleic anhydride, or one of its salts; a copolymer of styrene-maleic acid, or one of its salts; a styrene-acrylic acid copolymer, or one of its salts, a styrene-methacrylic acid copolymer, or one of its salts, a styrene-fumaric acid copolymer, or one of its salts, a styrene-acrylonitrile-acrylic acid copolymer, or one of its salts, a styrene-butyl acrylate-acrylic acid copolymer, or one of its salts; a copolymer of styrene-acrylic ester dispersed in a copolymer of styrene-maleic acid, or one of its salts, and mixtures thereof, wherein the cationic polymer is selected from the group consisting of a polyamine; a polyethylene imine; a styrene-maleic anhydride copolymer imide quaternary ammonium salt; a polyamidoamine-epichlorohydrin resin; a dialkylamine-epichlorohydrin resin; a homo- or copolymer of diallyldimethyl-ammonium chloride; a homo- or copolymer of a vinyl amine; a homo- or copolymer of a (meth)acrylamide; a homo- or copolymer of a (meth)acrylate, and corresponding acid addition salts and quaternary ammonium salts thereof, and wherein the anionic and cationic polymers are provided in a weight ratio of anionic polymer to cationic polymer of between about 0.2:1 to about 2.5:1.  
     
     
         13 . A method of sizing a cellulosic web comprising applying to a surface of the cellulosic web an aqueous sizing composition comprising a mixture of a film-forming binder, an anionic polymer and a cationic polymer.  
     
     
         14 . The method of  claim 13  wherein the film-forming binder is a starch.  
     
     
         15 . The method of  claim 14  wherein the cationic polymer and starch are provided using a cationic polymer-grafted onto said starch.  
     
     
         16 . The method of  claim 14  wherein the anionic polymer and starch are provided using an anionic polymer-grafted onto said starch.  
     
     
         17 . The method of  claim 14  wherein the anionic polymer is selected from the group consisting of a hydrolyzed copolymer of styrene-maleic anhydride, or one of its salts; a copolymer of styrene-maleic acid, or one of its salts; a styrene-acrylic acid copolymer, or one of its salts, a styrene-methacrylic acid copolymer, or one of its salts, a styrene-fumaric acid copolymer, or one of its salts, a styrene-acrylonitrile-acrylic acid copolymer, or one of its salts, a styrene-butyl acrylate-acrylic acid copolymer, or one of its salts; a copolymer of styrene-acrylic ester dispersed in a copolymer of styrene-maleic acid, or one of its salts, and mixtures thereof.  
     
     
         18 . The method of  claim 14  wherein the anionic polymer is an alkali soluble, acid containing copolymer  
     
     
         19 . The method of  claim 18  wherein the cationic polymer is selected from the group consisting of a polyamine; a polyethylene imine; a styrene-maleic anhydride copolymer imide quaternary ammonium salt; a polyamidoamine-epichlorohydrin resin; a dialkylamine-epichlorohydrin resin; a homo- or copolymer of diallyldimethyl-ammonium chloride; a homo- or copolymer of a vinyl amine; a homo- or copolymer of a (meth)acrylamide; a homo- or copolymer of a (meth)acrylate, and corresponding acid addition salts and quaternary ammonium salts thereof.  
     
     
         20 . The method of sizing of  claim 13  wherein the aqueous sizing composition comprises a mixture of starch grafted with a copolymer of diallyldimethylammonium chloride-acrylamide and an alkali soluble, acid containing copolymer.  
     
     
         21 . The method of  claim 13  wherein the aqueous sizing composition comprises an anionic polymer latex having sulfonic or carboxylic moieties and a polyamidoamine-epichlorohydrin resin.  
     
     
         22 . The method of  claim 13  wherein the aqueous sizing composition comprises a copolymer of styrene-acrylic ester dispersed in a copolymer of styrene-maleic acid, or one of its salts and a polyamidoamine-epichlorohydrin resin.  
     
     
         23 . The method of  claim 20  wherein the alkali soluble, acid containing copolymer is selected from the group consisting of a hydrolyzed copolymer of styrene-maleic anhydride, or one of its salts; a copolymer of styrene-maleic acid, or one of its salts; a styrene-acrylic acid copolymer, or one of its salts, a styrene-methacrylic acid copolymer, or one of its salts, a styrene-acrylonitrile-acrylic acid copolymer, or one of its salts, a styrene-butyl acrylate-acrylic acid copolymer, or one of its salts and mixtures thereof.  
     
     
         24 . A sized cellulosic web made by the method of  claim 13 ,  14 ,  15 ,  16 ,  17 ,  18 ,  19 ,  20 ,  21 ,  22  or  23 .