Bonding of paper using latex-dispersions of copolymers made of hydrophobic monomers/polymers of styrene/maleic anhydride type of low molecular mass

Abstract

Such latex-dispersions used in paper bonding formulations make it possible to obtain acceptable COBB values, even with printing and writing papers or wrapping papers obtained from recycled or de-inked mechanical pulps.

1 . Application of latex-dispersions, such as those resulting from the polymerization of a mixture of hydrophobic monomers composed of styrene and of (meth)acrylic esters in emulsion in an aqueous solution of a water-soluble or water-dispersible amphiphilic copolymer consisting of a combination of hydrophobic monomers and hydrophilic monomers bearing carboxylic acid functions, in the presence of a radical initiator, in which the said amphiphilic copolymer has a molecular mass of between 500 and 5,000, to the bonding of papers.  
     
     
         2 . Application of latex-dispersions according to  claim 1 , characterized in that, in the latex-dispersions, the copolymer with a molecular mass of between 500 and 5,000 is a copolymer of one or more hydrophobic monomers taken from the group consisting of styrene or derivatives thereof, isobutylene or derivatives thereof and (meth)acrylic esters and of one or more hydrophilic monomers taken from the group consisting of (meth)acrylic acid and maleic anhydride, it being possible for the latter to be partially modified with an alcohol or an amine while at the same time remaining water-soluble or water-dispersible in aqueous medium.  
     
     
         3 . Application of latex-dispersions according to  claim 1 , characterized in that, in the latex-dispersions, the copolymer with a molecular mass of between 500 and 5,000 is a copolymer of styrene and of maleic anhydride in which the anhydride part may or may not be modified with an alcohol or an amine and in which the acid number is between 150 and 500.  
     
     
         4 . Application of latex-dispersions according to  claim 1 , characterized in that, in the latex-dispersions, the hydrophobic monomers are taken from the group consisting of styrene and derivatives thereof, (meth)acrylic esters, including fluoro(meth)acrylic esters resulting from the esterification of (meth)acrylic acid with a perfluoro alcohol, or a mixture of these monomers.  
     
     
         5 . Application according to any one of  claims 1  to  4 , in which the paper is a printing and writing paper.  
     
     
         6 . Application according to any one of  claims 1  to  4 , in which the paper is a wrapping paper.  
     
     
         7 . Application according to any one of  claims 1  to  4 , in which the paper is a wrapping paper made from a de-inked mechanical pulp or from a recycled pulp.