Sizing dispersion

Abstract

An aqueous dispersion of a sizing agent comprising starch having aromatic groups and a condensed sulfonate, wherein the starch contains less than 95 weight % of amylopectin.

1 . An aqueous sizing dispersion comprising a sizing agent, starch having aromatic groups and a condensed sulfonate, wherein the starch contains less than 95 weight % of amylopectin.  
     
     
         2 . The aqueous dispersion according to  claim 1 , wherein the starch contains less than 90 weight % of amylopectin.  
     
     
         3 . The aqueous dispersion according to  claim 1 , wherein the condensed sulfonate is a condensation product of aromatic sulfonic acids and aldehyde.  
     
     
         4 . The aqueous dispersion according to  claim 1 , wherein the condensed sulfonate is a condensation product of aromatic sulfonic acids and formaldehyde.  
     
     
         5 . The aqueous dispersion according to  claim 1 , wherein the condensed sulfonate is a condensation product derived from aromatic compounds selected from naphthalene, naphthalene and cresol, diphenyl ether, toluene, isopropylbenzene, cresol, and phenol.  
     
     
         6 . The aqueous dispersion according to  claim 1 , wherein the condensed sulfonate is a condensation product of naphthalene sulfonic acid and formaldehyde.  
     
     
         7 . The aqueous dispersion according to  claim 1 , wherein the sizing agent is a cellulose-reactive sizing agent.  
     
     
         8 . A method of sizing paper comprising adding an aqueous sizing dispersion comprising a sizing agent, starch having aromatic groups containing less than 95 weight % of amylopectin and a condensed sulfonate, to an aqueous suspension containing cellulosic fibres, forming and dewatering the suspension on a wire, wherein the suspension has a conductivity of at least 0.5 mS/cm.  
     
     
         9 . The method of sizing paper according to  claim 8 , wherein the suspension has a conductivity of at least 4.5 mS/cm.  
     
     
         10 . The method of sizing paper according to  claim 8 , wherein the starch contains less than 90 weight % of amylopectin.  
     
     
         11 . The method of sizing paper according to  claim 8 , wherein the condensed sulfonate is a condensation product of naphthalene sulfonic acid and formaldehyde.  
     
     
         12 . The method of sizing paper according to  claim 8 , wherein the sizing agent is a cellulose-reactive sizing agent.  
     
     
         13 . An aqueous sizing dispersion comprising a sizing agent, starch having the general structural formula (I):  
       
         
           
           
               
               
           
         
       
       wherein P is a residue of a starch; A is a chain of atoms comprising C and H atoms attaching N to the polysaccharide residue, R 1  and R 2  are each H or a hydrocarbon group, R 3  is an aromatic hydrocarbon group, n is an integer from 2 up to 300000, and X −  is an anionic counter ion, and a condensed sulfonate, wherein the starch contains less than 95 weight % of amylopectin.  
     
     
         14 . The aqueous dispersion according to  claim 13 , wherein the starch contains less than 90 weight % of amylopectin.  
     
     
         15 . The aqueous dispersion according to  claim 13 , wherein the condensed sulfonate is a condensation product of aromatic sulfonic acids and aldehyde.  
     
     
         16 . The aqueous dispersion according to  claim 13 , wherein the condensed sulfonate is a condensation product of aromatic sulfonic acids and formaldehyde.  
     
     
         17 . The aqueous dispersion according to  claim 13 , wherein the condensed sulfonate is a condensation product derived from aromatic compounds selected from naphthalene, naphthalene and cresol, diphenyl ether, toluene, isopropylbenzene, cresol, and phenol.  
     
     
         18 . The aqueous dispersion according to  claim 13 , wherein the condensed sulfonate is a condensation product of naphthalene sulfonic acid and formaldehyde.  
     
     
         20 . The aqueous dispersion according to  claim 13 , wherein R 1  and R 2  are alkyl groups having at least 2 carbon atoms, and R 3  is an aralkyl group including benzyl and phenylethyl groups.  
     
     
         21 . The aqueous dispersion according to  claim 13 , wherein the sizing agent is a cellulose-reactive sizing agent.  
     
     
         22 . The aqueous dispersion according to  claim 13 , wherein the sizing agent is selected from ketene dimers and acid anhydrides.  
     
     
         23 . A method of sizing paper comprising adding an aqueous sizing dispersion comprising a sizing agent, starch having the general structural formula (I):  
       
         
           
           
               
               
           
         
       
       wherein P is a residue of a starch; A is a chain of atoms comprising C and H atoms attaching N to the polysaccharide residue, R 1  and R 2  are each H or a hydrocarbon group, R 3  is an aromatic hydrocarbon group, n is an integer from 2 up to 300000, and X −  is an anionic counter ion, and a condensed sulfonate, the starch containing less than 95 weight % of amylopectin, and a condensed sulfonate, to an aqueous suspension containing cellulosic fibres, forming and dewatering the suspension on a wire, wherein the suspension has a conductivity of at least 0.5 mS/cm.  
     
     
         24 . The method of sizing paper according to  claim 23 , wherein the suspension has a conductivity of at least 4.5 mS/cm.  
     
     
         25 . The method of sizing paper according to  claim 23 , wherein the starch contains less than 90 weight % of amylopectin.  
     
     
         26 . The method of sizing paper according to  claim 23 , wherein the condensed sulfonate is a condensation product of naphthalene sulfonic acid and formaldehyde.  
     
     
         27 . The method of sizing paper according to  claim 23 , wherein the sizing agent is a cellulose-reactive sizing agent.