Method for repulping wet strength fiber

Abstract

The present disclosure is directed to a method for repulping lignocellulosic fibers having at least one wet strength resin disposed thereon, the method comprising:a) preparing an aqueous slurry comprising (1) the lignocellulosic fiber, (2) the resin, and (3) an enzymatic agent present in an amount of from about 0.01 to about 1 wt. %, based on the dry weight of the lignocellulosic fiber, wherein the enzymatic agent comprises:i) at least one hemicellulase; and,ii) at least one cellulase; and,b) agitating the slurry.

What is claimed is: 
     
         1 . A method for repulping lignocellulosic fibers having at least one wet strength resin disposed thereon, the method comprising:
 a) preparing an aqueous slurry of (1) the lignocellulosic fibers, (2) the resin, and (3) an enzymatic agent present in an amount of from about 0.01 to about 1 wt. %, based on the dry weight of the lignocellulosic fiber, wherein the enzymatic agent comprises:
 i) at least one hemicellulase; and, 
 ii) at least one cellulase; and, 
   b) agitating the slurry.   
     
     
         2 . The method according to  claim 1 , wherein at least a portion of the lignocellulosic fibers are provided from paper broke. 
     
     
         3 . The method according to  claim 1 , wherein the lignocellulosic fibers comprise or consist of wet strength secondary fiber. 
     
     
         4 . The method according to  claim 1 , wherein the wet strength resin is covalently bound to the lignocellulosic fibers. 
     
     
         5 . The method according to  claim 1 , wherein the wet strength resin is a polyamine-epichlorohydrin resin. 
     
     
         6 . The method according to  claim 1 , wherein the step of preparing comprises:
 i) adding the lignocellulosic fiber to an aqueous liquid under agitation; and,   ii) dispersing the enzymatic agent into the agitated aqueous liquid to form the aqueous slurry.   
     
     
         7 . The method according to  claim 1 , wherein the at least one hemicellulase is chosen from: xylanase; α-L-arabinofuranosidase; acetyl xylan esterase; α-d-glucuronidase; α-d-galactosidase; mannanase; endo-polygalacturonase; endoarabinase; exoarabinase; exo-β-1,3-galactanase; xyloglucan-specific exo-beta-1,4-glucanase ferulic acid esterase; galactomannanase; and, combinations thereof. 
     
     
         8 . The method according to  claim 1 , wherein the at least one hemicellulase comprises or consists of at least one xylanase. 
     
     
         9 . The method according to  claim 8 , wherein the xylanase is chosen from: endoxylanases; exoxylanases; D3-xylosidases; and, combinations thereof. 
     
     
         10 . The method according to  claim 1 , wherein the at least one cellulase is chosen from: cellobiohydrolase (CBH); endoglucanase (EG); beta-glucosidase (BG); and, combinations thereof. 
     
     
         11 . The method according to  claim 1 , wherein the ratio by weight of hemicellulase to cellulase in the enzymatic agent is from 10:1 to 1:10. 
     
     
         12 . The method according to  claim 1 , wherein the enzymatic agent further comprises at least one de-inking enzyme chosen from lipases, pectinases, ligninolytic enzymes and combinations thereof. 
     
     
         13 . The method according to  claim 1 , wherein the enzymatic agent comprises or consists of, based on the weight of the enzymatic agent:
 from 30 to 100 wt. % of the sum of the i) at least one hemicellulase and ii) at least one cellulase;   from 0 to 30 wt. % of iii) at least one proteolytic enzyme;   from 0 to 30 wt. % of iv) at least one esterase which does not have hemicellulase or cellulase activity; and,   from 0 to 30 wt. % of v) at least one amylase chosen from α-amylase, β-amylase, γ-amylase and combinations thereof.   
     
     
         14 . The method according to  claim 13 , wherein the enzymatic agent comprises the at least one proteolytic enzyme. 
     
     
         15 . The method according to  claim 14 , wherein the enzymatic agent comprises at least one protease chosen from: pronase; trypsin; chymotrypsin; bromelain; pepsin; collagenase; papain; and, combinations thereof. 
     
     
         16 . The method according to  claim 13 , wherein the enzymatic agent comprises the at least one esterase which does not have hemicellulase or cellulase activity. 
     
     
         17 . The method according to  claim 13 , wherein the enzymatic agent comprises the at least one amylase chosen from α-amylase, β-amylase, γ-amylase and combinations thereof. 
     
     
         18 . The method of  claim 1 , wherein the step of agitating is performed for a duration of from 5 to 75 minutes. 
     
     
         19 . The method according to  claim 1 , wherein the aqueous slurry comprises less than 1000 ppm by weight of oxidizing agents. 
     
     
         20 . The method according to  claim 1 , wherein the aqueous slurry comprises less than 1000 ppm by weight of hypochlorite salts.