METHOD FOR REPULPING WET STRENGTH FIBER
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.
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.