Starch Derivatives for Use in Paper Sizing and/or Coating Compositions

Abstract

The present invention relates to a method of preparing a starch-based composition, characterised in that it comprises: (a) mixing a starch substrate with sodium perborate; (b) adding water to the mix of step (a) to form a slurry; and (c) pasting the slurry of step (b). The invention further relates to starch-based compositions prepared in accordance with said method, paper sizing and/or coating compositions comprising said starch-based compositions and paper products treated with said sizing and/or coating compositions.

1 . A starch-based composition prepared by a method comprising the steps of:
 (a) obtaining a mixture of thermally modified starch substrate and sodium perborate;   (b) adding water to the mix of step (a) to form a slurry; and   (c) pasting the slurry of step (b) at a temperature of 80-140° C.;   
     provided that the method does not include the step of adding an effective amount of hydrolytic enzyme to the slurry. 
   
   
       2 . The composition of  claim 1 , wherein the thermally modified starch is dextrin. 
   
   
       3 . The composition of  claim 1 , wherein the method further comprises mixing the starch substrate of step (a) or the slurry of step (b) with sodium carbonate and/or calcium carbonate. 
   
   
       4 . The composition of  claim 1 , wherein 0.01-1.25 parts sodium perborate, on a dry weight basis, are mixed to 100 parts starch substrate in step (a). 
   
   
       5 . The composition of  claim 1 , wherein 0.01-0.35 parts sodium perborate, on a dry weight basis, are mixed to 100 parts starch substrate in step (a). 
   
   
       6 . The composition of  claim 1 , wherein the slurry of step (b) comprises 0.5-50% weight dry substance. 
   
   
       7 . The composition of  claim 1 , wherein step (c) is carried out at a temperature of 90-130° C. 
   
   
       8 . The composition of  claim 7 , wherein step (c) lasts for 1-45 min. 
   
   
       9 . A paper sizing and/or coating composition comprising a starch-based composition, wherein said starch based composition is prepared by a method comprising the steps of:
 (a) obtaining a mixture of thermally modified starch substrate and sodium perborate;   (b) adding water to the mix of step (a) to form a slurry;   (c) pasting the slurry of step (b) at a temperature of 80-140° C.; and   (d) adding to the paste of step (c) one or more additional paper sizing and/or coating composition ingredients,   
     provided that the method does not include the step of adding an effective amount of hydrolytic enzyme to the slurry. 
   
   
       10 . The composition of  claim 9 , wherein the thermally modified starch is dextrin. 
   
   
       11 . The composition of  claim 9 , wherein the method further comprises mixing the starch substrate of step (a) or the slurry of step (b) with sodium carbonate and/or calcium carbonate. 
   
   
       12 . The composition of  claim 9 , wherein 0.01-1.25 parts sodium perborate, on a dry weight basis, are mixed to 100 parts starch substrate in step (a). 
   
   
       13 . The composition of  claim 9 , wherein 0.01-0.35 parts sodium perborate, on a dry weight basis, are mixed to 100 parts starch substrate in step (a). 
   
   
       14 . The composition of  claim 9 , wherein the slurry of step (b) comprises 0.5-50% weight dry substance. 
   
   
       15 . The composition of  claim 9 , wherein step (c) is carried out at a temperature of 90-130° C. 
   
   
       16 . The composition of  claim 15 , wherein step (c) lasts for 1-45 min.