Starch compositions and the use thereof in the wet-end of paper preparation

Abstract

The present invention relates to compositions of starch compositions consist of an anionic and a cationic starch wherein at least one o,the starches is waxy. The compositions are surprisingly not resulting in an agglomerated product when cooked. The compositions are used in paper or cardboard preparation. The compositions are cooked and added at the wet end of the paper production process. This results in a high Possible addition level and the use of the size press is abolished. The resulting paper and board are shown to have better characteristics than the paper and board prepared with the same components which have not been mixed prior to addition but which are added separately.

1 . A composition of matter which consists of an anionic and a cationic starch wherein at least one of the starches is waxy starch.  
     
     
         2 . A composition of matter according to  claim 1  consisting of an anionic and a cationic starch having an anionic demand (PCD) of lower than 200 μeq.  
     
     
         3 . A composition according to  claim 1  wherein the anionic starch is oxidised waxy starch modified with maleic or succinic anhydride.  
     
     
         4 . A composition of matter according  claim 1  wherein the ratio of anionic to cationic starch is between 1:10 and 10:1 (w/w).  
     
     
         5 . A method for producing paper or bond comprising the step of 
 a) cooking a composition consisting of an anionic and a cationic starch and wherein at least one of the starches is a waxy starch,    b) adding the cooked composition of the previous step to the wet-end of the paper production process and    c) drying the paper or board.    
     
     
         6 . A method according to  claim 5  in the composition of step a) the ratio of anionic to cationic starch is between 1:10 and 10:1 (w/w).  
     
     
         7 . Paper or board comprising a composition according to any one of  claims 1  to  4  in an amount of between 1 and 10% (w/w) preferably between 2 and 8% and more preferably between 4 and 6%.  
     
     
         8 . A process for preparing paper or board wherein the use of the size press is replaced by the addition of a composition as claimed in any ore of  claims 1  to  4 .