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

Abstract

The present invention relates to compositions of starch. The compositions consist of an anionic and a cationic starch wherein at least one of 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 starch composition in which the starch consists of an anionic and a cationic starch, wherein at least one of the starches is waxy starch, said composition is at least slightly cationic, and the anionic starch is oxidized waxy starch modified with maleic or succinic anhydride. 
     
     
       2. A starch composition according to  claim 1  consisting of an anionic and a cationic starch, said composition having an anionic demand of lower than 200 μeq/l. 
     
     
       3. A starch composition according to  claim 1  wherein the ratio of anionic to cationic starch is between 1:10 and 10:1 (w/w). 
     
     
       4. A starch composition according to  claim 1 , wherein said starch composition has an anionic demand of less than 100 μeq/l. 
     
     
       5. A starch composition according to  claim 1 , wherein said starch composition is a dry blend of said anionic and cationic starch. 
     
     
       6. A starch composition according to  claim 1 , wherein said starch composition is a slurry. 
     
     
       7. A starch composition according to  claim 1  wherein said anionic starch is a waxy starch modified with maleic anhydride.  
     
     
       8. A starch composition according to  claim 1  wherein said anionic starch is modified with succinic anhydride.  
     
     
       9. A starch composition consisting essentially of anionic starch and cationic starch, wherein at least one of the starches is waxy starch, said composition is at least slightly cationic, and said ionic starch consists essentially of waxy starch modified with maleic or succinic anhydride.  
     
     
       10. A starch composition according to  claim 9  wherein said composition has an anionic demand of lower than  200  μeq/l.  
     
     
       11. A starch composition according to  claim 9  wherein said starch composition has an anionic demand of less than  100  μeq/l.  
     
     
       12. A starch composition according to  claim 9  wherein the ratio of anionic starch to cationic starch is between  1 : 10  and  10 : 1  ( w/w ).  
     
     
       13. A starch composition according to  claim 9  wherein the ratio of anionic starch to cationic starch is  60 %  w/w to  40   %  w/w.    
     
     
       14. A starch composition according to  claim 9  wherein said cationic starch is cationic maize starch.  
     
     
       15. A starch composition according to  claim 9  wherein said cationic starch is cationic potato starch.  
     
     
       16. A starch composition according to  claim 9  wherein said cationic starch is waxy cationic starch.  
     
     
       17. A starch composition according to  claim 9  wherein said starch composition is a dry blend of said anionic starch and said cationic starch.  
     
     
       18. A starch composition according to  claim 9 , wherein said starch composition is a slurry.