Coating composition comprising hydrolysed wheat proteins

Abstract

A paper or cardboard coating composition having a dry matter content of between 45% and 80%, comprising i) binders which include at least one modified starch and one adhesive, ii) a hydrolyzed wheat protein having an average molecular weight of between 7 and 1000 kDa, and iii) a mineral filler, and also the method for obtaining such a composition. A method for coating or brightening paper or cardboard, comprising the steps consisting of i) the provision of a composition as described, and ii) the depositing of said composition on a paper or cardboard substrate, and to the coated paper or cardboard thus obtained. Finally, the use of a hydrolyzed wheat protein in the replacement of latex in a paper or cardboard coating composition.

1 . A paper or cardboard coating composition having a dry matter content of between 45% and 80% comprising:
 binders including at least one modified starch and one synthetic adhesive,   a hydrolyzed wheat protein having an average molecular weight of between 7 and 1000 kDa, and   a mineral filler.   
     
     
         2 . The composition as claimed in  claim 1 , characterized in that the hydrolyzed wheat protein has an average molecular weight of between 8 and 100 kDa. 
     
     
         3 . The composition as claimed in  claim 1 , characterized in that it comprises, in parts per 100 parts by weight of mineral filler:
 1 to 99 parts of binders, and   1 to 50 parts by weight of wheat protein.   
     
     
         4 . The composition as claimed in  claim 1 , characterized in that it comprises a modified starch/synthetic adhesive ratio of from 1:5 to 5:1. 
     
     
         5 . The composition as claimed in  claim 1 , characterized in that it comprises a binders/wheat protein ratio of from 1:5 to 5:1. 
     
     
         6 . The composition as claimed in  claim 1 , characterized in that the modified starch is chosen from a pregelatinized starch, a dextrin, a hydrolyzed starch, an oxidized starch, a starch ester, a starch ether, a crosslinked starch and mixtures thereof. 
     
     
         7 . The composition as claimed in  claim 6 , characterized in that the dextrin modified starch comprises a dextrin and the dextrin has a molecular weight of between 20 and 300 kDa, and/or a viscosity of between 50 and 400 mPa·s. 
     
     
         8 . The composition as claimed in  claim 1 , characterized in that the synthetic adhesive is chosen from the group made up of latexes, vinyl acetates, polyvinyl alcohol, sodium carboxymethylcellulose and hydroxyethylcellulose. 
     
     
         9 . The composition as claimed in  claim 1 , characterized in that the synthetic adhesive is a latex preferentially chosen from the group made up of styrene-butadiene latexes, polyvinyl alcohol latexes and acrylic copolymer latexes. 
     
     
         10 . A method for producing a paper or cardboard coating composition, comprising the following steps:
 mixing, with stirring, a mineral filler and binders which include at least one modified starch and one synthetic adhesive,   adding, with stirring, to the mixture obtained, a hydrolyzed wheat protein having an average molecular weight of between 7 and 1000 kDa, and   adding water, with stirring, so as to obtain a composition having a dry matter content of between 45% and 80%.   
     
     
         11 . A method for coating or brightening paper or cardboard, said method comprising the steps consisting of
 (a) the provision of a composition having a dry matter content of between 45% and 80% and comprising binders, including at least one modified starch and one synthetic adhesive, a hydrolyzed wheat protein having an average molecular weight of between 7 and 1000 kDa, and a mineral filler, and   (b) the depositing of said composition on a paper or cardboard substrate.   
     
     
         12 . A paper or cardboard coated with a composition having a dry matter content of between 45% and 80% and comprising binders, including at least one modified starch and one synthetic adhesive, a hydrolyzed wheat protein having an average molecular weight of between 7 and 1000 kDa, and a mineral filler, or a composition obtained by mixing, with stirring, a mineral filler and binders which include at least one modified starch and one synthetic adhesive, adding, with stirring, to the mixture obtained, a hydrolyzed wheat protein having an average molecular weight of between 7 and 1000 kDa, and adding water, with stirring, so as to obtain a composition having a dry matter content of between 45% and 80%. 
     
     
         13 . A method of using a hydrolyzed wheat protein, comprising substituting the hydrolyzed wheat protein for latex in a process for making a paper or cardboard coating composition, said hydrolyzed wheat protein having an average molecular weight of between 7 and 1000 kDa. 
     
     
         14 . The method of use as claimed in  claim 13 , characterized in that said composition comprises:
 binders which include at least one modified starch and one preferentially synthetic adhesive,   a hydrolyzed wheat protein having an average molecular weight of between 7 and 1000 kDa, and   a mineral filler.   
     
     
         15 . The method of use as claimed in  claim 13 , characterized in that the binders/wheat protein ratio is from 1:5 to 5:1. 
     
     
         16 . The composition as claimed in  claim 1 , wherein the composition has a dry matter content of between 50% and 78%. 
     
     
         17 . The composition as claimed in  claim 1 , characterized in that the hydrolyzed wheat protein has an average molecular weight of between 9 and 80 kDa 
     
     
         18 . The method of  claim 10 , wherein said modified starch has previously undergone a cooking step. 
     
     
         19 . The method of  claim 10 , wherein said hydrolyzed wheat protein is in a pulverulent form. 
     
     
         20 . The method of  claim 10 , wherein the adding of water is carried out with the mineral filler and/or the modified starch and/or the hydrolyzed protein.