Process for reducing sticky contaminants in stock systems containing waste paper and in coated broke

Abstract

The invention relates to a process for reducing sticky contaminants in stock systems containing waste paper and in coated broke, and their reuse in the manufacture of papers. In this process, both polyvinyl alcohols and bentonite are added.

1 . Process for reducing sticky contaminants, in particular those with a finely divided composition (microstickies) in the preparation of stock systems containing waste paper and of coated broke, characterized in that, after mechanical preparation has been carried out and, if necessary, coarse sticky constituents (macrostickies) have been separated, the stock system has added to it at least one water-soluble organic polyol, in particular a water-soluble organic polyvinyl alcohol or a mixture of various water-soluble polyols, in particular of water-soluble organic polyvinyl alcohols, and at least one bentonite or a mixture of different bentonites and, if appropriate, further chemical additives and filler.  
     
     
         2 . Process according to    claim 1   , characterized in that the organic polyvinyl alcohols used are water-soluble polymers with proportions of vinyl alcohol or a copolymer of vinyl alcohol and vinyl acetate, which contain hydrophobic groups and are hydrolyzed to more than 70% by weight, being used after the mechanical preparation in proportions from 0.05 to 2% by weight, in particular from 0.1 to 1% by weight, based on fibrous material, in combination with bentonites with a high specific surface, preferably alkali modified bentonites, in proportions from 1 to 10% by weight, based on fibrous material.  
     
     
         3 . Process according to    claim 1   , characterized in that the organic polyvinyl alcohols used have a molecular weight from 1 000 to 250 000, preferably 9 000 to 150 000.  
     
     
         4 . Process according to    claim 1   , characterized in that the prepared stock mixture has added to it cationic fixing agents in proportions from 0.05 to 1% by weight, based on fibrous material.  
     
     
         5 . Process according to    claim 1   , characterized in that further chemical additives and fillers are mixed in.  
     
     
         6 . Paper which is produced by means of a secondary fibrous material mixture prepared in accordance with    claim 1   .