Enzymatic Treatment of Paper Making Pulps

Abstract

The invention relates to processes for treating a pulp, and for making a paper material such as paper, cardboard linerboard, corrugated paperboard, tissue, towels, corrugated containers boxes etc. these processes comprising an alkaline treatment of a pulp, a treatment with a pectin lyase and/or a pectate lyase, and, if desired, a draining of the pulp. Pectate lyase in combination with pectinesterase may be substituted for pectin lyase. The invention also relates to the use of xylanase, pectin lyase, pectate lyase, and/or the combination of pectate lyase with pectinesterase for anionic trash reduction and/or reduction of cationic demand of a paper pulp.

1 . A process for the treatment of a paper making pulp, the process comprising the following steps: a) an alkaline treatment of the pulp, b) a treatment of the pulp with a pectin lyase, a pectate lyase, or a combination of a pectate lyase and a pectinesterase.  
   
   
       2 . The process of  claim 1 , wherein 
 (i) the pectate lyase treatment follows the alkaline treatment step;    (ii) the pectate lyase treatment is followed by the alkaline treatment step;    (iii) the pectin lyase treatment is followed by the alkaline treatment step;    (iv) the treatment with a combination of pectate lyase and pectinesterase is followed by the alkaline treatment step; or    (v) the treatment with a combination of pectate lyase and pectinesterase follows the alkaline treatment step.    
   
   
       3 . The process of anyone of  claim 1 , further comprising step G) a draining of the pulp.  
   
   
       4 . The process of  claim 3  which is a process for making a paper material.  
   
   
       5 . The process of  claim 1 , wherein the enzyme treatment of step b) leads to the formation of unsaturated oligomers with a 4,5 carbon-carbon double bond in the non-reducing end, resulting in degradation products exhibiting a distinct UV absorbance at 235 nm.  
   
   
       6 . The process of  claim 3 , wherein step c) follows steps a) and b).  
   
   
       7 . The process of  claim 1  which comprises at least one of the following additional steps: d) debarking, e) chipping, f) refining, g) screening, h) cleaning, i) thickening, j) storage, k) forming the paper material, and/or l) drying the paper material.  
   
   
       8 . The process of  claim 1 , wherein the alkaline treatment is a hydrogen peroxide or hydrosulphite bleaching, or a repulping of recycled pulp.  
   
   
       9 . The process of  claim 1 , wherein the pulp is additionally treated with a potygalacturonase and/or a pectate disaccharide-lyase.  
   
   
       10 . The process of  claim 1 , wherein the enzymes are added to wash water, white water process water, and/or drained water.  
   
   
       11 . The process of  claim 1 , wherein the enzymes are added together with complexing agents and/or surfactants.  
   
   
       12 . A method of reducing the cationic demand and/or the content of anionic trash in a pulp, the method comprising the steps of a) an alkaline treatment of the pulp, b) a treatment of the pulp with i) a xylanase, and/or ii) a pectin lyase, a pectate lyase, or a combination of a pectate lyase and a pectinesterase.  
   
   
       13 . The method of  claim 12 , wherein 
 (i) the pectate lyase treatment follows the alkaline treatment step;    (ii) the pectate lyase treatment is followed by the alkaline treatment step;    (iii) the pectin lyase treatment is followed by the alkaline treatment step;    (iv) the treatment with a combination of pectate lyase and pectinesterase is followed by the alkaline treatment step;    (v) the treatment with a combination of pectate lyase and pectinesterase follows the alkaline treatment step;    (vi) the xylanase treatment follows the alkaline treatment step; and/or    (vii) the xylanase treatment is followed by the alkaline treatment step.    
   
   
       14 . The method of  claim 12 , wherein step b) includes a treatment of the pulp with a pectinase.