Polymer and use thereof in the production of paper and board

Abstract

As additive for the production of paper and board to improve the strength of a wet web a copolymer stabilized with a cationic polysaccharide is proposed in which copolymer an acrylamide of metacrylamide, vinylic carboxyl acid and optionally other vinylic monomers are used as monomers. The wet strength of a web means the strength of a paper or board web during production at a dry solids content of 20-60%. The additive according to the invention improves, in addition to the wet strength of the web, also the surface resistance of the product. Compared to the additives of the prior art, a small relative ratio of the number of the side chains to the cationic groups is used, because a polysaccharide having a higher cationic character has been found to provide better stability.

1 . An additive for the production of paper and board, containing a product polymerized from at least one vinylic monomer in the presence of a cationic saccharide, characterized in that the cationic polysaccharide has a degree of substitution of 0.02-0.50, and that monomers in the amount of up to 30% calculated on the dry weight of the starting materials are used in the polymerization, whereby at least 95% of the molar amount of the monomer component is amide.  
     
     
         2 . The additive according to  claim 1 , characterized in that up to 5% of the molar amount of the monomer component is vinylic carboxylic acid.  
     
     
         3 . The additive according to  claim 1  or  2 , characterized in that monomers in the amount of up to 20% calculated on the dry weight of the starting materials are used in the polymerization.  
     
     
         4 . The additive according any of  claims 1  to  3 , characterized in that the polysaccharide is degraded starch.  
     
     
         5 . A use of the additive according to  claim 1  in the production of paper and board.  
     
     
         6 . The use according to  claim 5 , characterized in that the additive is added in an amount of 1-3 kg per ton of the dry solids of the pulp.