Use of an aqueous dispersion of biodegradable polyesters

Abstract

The present invention relates to the use of an aqueous dispersion of at least one biodegradable polyester in the form of a coating for improving the barrier properties of packaging materials made of paper or paperboard, in particular of packaging materials made of recycled paper or paperboard, with respect to mineral oils. The present invention also relates to a process for producing barrier coatings on paper or paperboard, in particular on recycled paper or paperboard.

1 .- 20 . (canceled) 
     
     
         21 . The use of an aqueous dispersion of at least one biodegradable polyester in the form of a coating for improving the barrier properties of packaging material made of paper or paperboard with respect to mineral oils. 
     
     
         22 . The use according to  claim 21 , where the packaging material has been produced at least to some extent from mineral-oil-contaminated recycling paper. 
     
     
         23 . The use according to  claim 21 , where the packaging material is intended for the packaging of food or drink. 
     
     
         24 . The use according to  claim 21 , where the weight per unit area of the coating is from 2 to 50 g/m 2 . 
     
     
         25 . The use according to  claim 21 , where the coating has at least two layers arranged on top of one another. 
     
     
         26 . The use according to  claim 25 , where the coating weight per unit area of each of the layers is from 1 to 30 g/m 2 . 
     
     
         27 . The use according to  claim 21 , where the content of biodegradable polyester, based on the total solids content of the polyester dispersion, accounts for at least 30% by weight. 
     
     
         28 . The use according to  claim 21 , where the biodegradable polyester is selected from the group of the aliphatic polyesters, aliphatic copolyesters, aliphatic-aromatic copolyesters, and mixtures of these. 
     
     
         29 . The use according to  claim 21 , where the polyester consists essentially of:
 a) at least one dicarboxylic acid component A, which is composed of
 a1) at least one aliphatic or cycloaliphatic dicarboxylic acid or ester-forming derivatives of these, or a mixture thereof, and 
 a2) optionally one or more aromatic dicarboxylic acids which have no sulfonic acid group, or ester-forming derivatives of these, or a mixture thereof, 
 a3) optionally one or more aromatic dicarboxylic acids which have at least one sulfonic acid group, or ester-forming derivatives of these, or a mixture thereof; 
   b) at least one diol component B selected from aliphatic and cycloaliphatic diols and mixtures of these;   c) optionally one or more other bifunctional compounds C which react to form bonds with carboxylic acid groups or with hydroxy groups; and   d) optionally one or more compounds D which have at least three functionalities which react to form bonds with carboxylic acid groups or with hydroxy groups;   
       where the molar ratio of component A to component B is in the range from 0.4:1 to 1:1, and components A and B account for at least 80% by weight of the polyester. 
     
     
         30 . The use according to  claim 29 , where the polyester consists essentially of:
 a) at least one dicarboxylic acid component A which is composed of
 a1) from 35 to 90 mol % of at least one aliphatic or cycloaliphatic dicarboxylic acid, or ester-forming derivatives of these, or a mixture thereof, and 
 a2) from 10 to 65 mol % of one or more aromatic dicarboxylic acids or ester-forming derivatives of these, or a mixture thereof; 
 a3) from 0 to 5 mol % of one or more aromatic dicarboxylic acids which have at least one sulfonic acid group, or ester-forming derivatives of these, or a mixture thereof, where the mol % data for components a1), a2), and a3) give a total of 100 mol %; 
   b) from 98 to 102 mol %, based on the total amount of components a1) and a2), of at least one diol component B selected from aliphatic and cycloaliphatic diols and mixtures of these;   c) from 0 to 2% by weight, based on the total weight of the polyester, of one or more other bifunctional compounds C which react to form bonds with carboxylic acid groups or with hydroxy groups; and   d) from 0 to 2% by weight, based on the total weight of the polyester, of one or more compounds D which have at least 3 functionalities which react to form bonds with carboxylic acid groups or with hydroxy groups.   
     
     
         31 . The use according to  claim 21 , where the number-average molecular weight of the polymer is in the range from 5000 to 1 000 000 daltons. 
     
     
         32 . The use according to  claim 21 , where the weight-average molecular weight of the polymer is in the range from 10 000 to 5 000 000 daltons. 
     
     
         33 . A process for producing a barrier coating on paper or paperboard via application of at least one aqueous dispersion of at least one biodegradable polyester as defined in  claim 21 , to at least one surface of the paper or paperboard, where a first layer is produced in a first step via application of the aqueous dispersion to a surface of the paper or paperboard, and then at least one further layer, arranged on the first layer, is produced in at least one further step via application of the aqueous dispersion to the first layer obtained in the first step. 
     
     
         34 . The process according to  claim 33 , where the amount of the polyester dispersion applied in each step is such that the resultant weight per unit area of the coating is in the range from 1 to 30 g/m 2  per layer. 
     
     
         35 . The process according to  claim 33 , where the amount of the polyester dispersions applied in the steps is such that the resultant total weight per unit area of the coating is in the range from 2 to 50 g/m 2 . 
     
     
         36 . The process according to  claim 33 , where the content of biodegradable polyester, based on the total solids content of the polyester dispersion, accounts for at least 30% by weight. 
     
     
         37 . The process according to  claim 33 , where the biodegradable polyester is a polyester according to  claim 28 . 
     
     
         38 . The process according to  claim 33 , where the paper or the paperboard has been produced at least to some extent from mineral-oil-contaminated recycling paper. 
     
     
         39 . The process according to  claim 33 , where the coated paper or the coated paperboard is intended to be packaging material for the packaging of food or drink. 
     
     
         40 . A coated paper or paperboard, obtainable according to  claim 33 .