U.S. patent application number 15/490990 was filed with the patent office on 2017-08-03 for method for making lignocellulosic paper and paper products.
The applicant listed for this patent is Solenis Technologies, L.P.. Invention is credited to Qu-Ming Gu, Josette Huynh-Ba.
Application Number | 20170218570 15/490990 |
Document ID | / |
Family ID | 56801786 |
Filed Date | 2017-08-03 |
United States Patent
Application |
20170218570 |
Kind Code |
A1 |
Gu; Qu-Ming ; et
al. |
August 3, 2017 |
Method for Making Lignocellulosic Paper and Paper Products
Abstract
Enzyme compositions comprising laccase, lipase, cationic
polymer, and optionally laccase activator, for papermaking
application are disclosed. It also relates to the use of the enzyme
composition to improve dry strength property of a paper product
made from lignocellulosic-containing materials before or after
mechanical refining in a papermaking process.
Inventors: |
Gu; Qu-Ming; (Bear, DE)
; Huynh-Ba; Josette; (Hockessin, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Solenis Technologies, L.P. |
Schaffhausen |
|
CH |
|
|
Family ID: |
56801786 |
Appl. No.: |
15/490990 |
Filed: |
April 19, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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14835931 |
Aug 26, 2015 |
9663899 |
|
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15490990 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D21H 17/72 20130101;
D21C 9/005 20130101; D21H 21/18 20130101; D21H 11/14 20130101; D21H
17/005 20130101; D21H 17/455 20130101; D21D 1/20 20130101; D21C
9/08 20130101 |
International
Class: |
D21H 17/00 20060101
D21H017/00; D21D 1/20 20060101 D21D001/20 |
Claims
1. A method of making a paper product with improved dry strength
comprising: providing a pulp furnish or suspension having a
temperature of from about 20.degree. C. to about 70.degree. C. and
pH of from about 4.0 to 9.0; treating the pulp furnish or
suspension with a composition comprising from about 3 wt. % to
about 40 wt. % dry weight of total composition laccase and from
about 1 wt. % to about 80 wt. % dry weight of total composition
lipase, wherein the laccase has at least 12 LAMU of laccase
activity and the lipase has from about 0.1 to about 10 KLU of
lipase activity per Kg of dry fiber, and wherein the composition is
added over a period of at least 0.1 hours; optionally refining the
treated pulp furnish or suspension using a mechanical refiner for
wood fiber; optionally adding additional papermaking additives to
the pulp furnish; and drying and forming the pulp furnish into the
desired paper product.
2. The method of claim 1, wherein pulp furnish or suspension is
recycled OCC fiber.
3. The method of claim 2, wherein the optional papermaking additive
is selected from the group consisting of starch, starch
derivatives, polyacrylamide derivatives, guar, poly(vinylamine),
polyethyleneimine, urea formaldehyde resin, epichlorohydrin reacted
poly(aminoamide), starch aldehyde and glycoxylated polyacrylamide,
flocculants, retention aids, drainage aids, debonders, softeners,
sizing agents for paper products, and creping adhesives and
enzymes.
4. The method of claim 3, wherein the enzymes are selected from the
group consisting of cellulases, hemicellulases, amylases,
proteases, lipases, esterases, pectinases, lyases, pectate lyase,
cellulase, oxidoreductases, glucose oxidases, and peroxidases.
5. The method according to claim 1, wherein the dry strength
composition can be added to the papermaking process either before,
during or after mechanical refining in a papermaking process.
Description
[0001] This application claims the benefit of U.S. Non-Provisional
patent application Ser. No. 14/835,931, filed 26 Aug. 2015, the
entire contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a method of making paper
and paper products. More specifically, a laccase, lipase and
cationic fixative polymer composition is added to a lignocellulosic
suspension to help improve dry strength of the paper and paper
products.
[0003] Paper pulp is typically processed from wood through the
Kraft processes. This process produces a cellulosic fiber with a
dark brown color, mostly due to the presence of lignin. For some
applications, lignin molecules are further removed by a process
known as bleaching to produce bleached fiber suitable for making
paper products such as tissue, towel, and printing and writing
paper. For other uses such as linerboard, unbleached fiber is
preferred because it is economical and also environmental friendly
for not going through bleaching process using toxic bleaching
chemicals. Unbleached Kraft fiber usually contains 1% to 2% lignin.
Although lignin is significantly reduced via the Kraft process, the
remaining lignin is embedded in cellulose, resulting in a
lignocellulosic material that requires more than 50% of the energy
that is needed to refine a bleached fiber mechanically in
papermaking processes. Other mechanical pulps such as thermal
mechanical pulp (TMP) is another type of unbleached fiber that is
widely used for papermaking. Lignocellulosic material is a term
used to describe the wood fiber that contains lignin molecules.
Many recycled brown furnishes are derived from a mixture of
different types of fibers with inferior quality than virgin fibers.
Recycled fibers, e.g., old corrugated container (OCC) and waste
newspaper, not only contain lignin, hemicellulose and other
biomass, but also contain a significant amount of contaminants
known as stickies and pitches such as polyvinyl acetate and ester
organic contaminants. These types of contaminants can interfere
with fiber to fiber bonding resulting in decreased dry strength of
the final product.
[0004] To restore dry strength properties of the paper product made
from recycled lignocellulosic material such as poor quality OCC
fiber, papermakers traditionally use synthetic polymeric dry
strength additives. The use of enzymes for papermaking has gained
popularity steadily due to the rapid developments of robust and
inexpensive enzyme products and its environmentally friendly
approach. Although cellulases are being used recently for paper dry
strength, the commercial success is limited to bleached virgin
fiber or drinking pulp (DIP). It is evident that accessibility of
cellulase to lignocellulosic fiber is hindered by lignin molecule
and other non-cellulosic biomasses bound with the cellulose.
Although many commercial trials have been attempted, cellulase is
generally not suitable for poor quality recycled lignocellulosic
fiber, or short fiber TMP, etc., for dry strength application.
Until now, no enzyme technology has achieved significant commercial
success in papermaking with recycled OCC fiber, particularly poor
quality OCC. Thus, there is a need of an environmentally friendly
and sustainable enzyme approach for recycled OCC or unbleached
virgin fiber as an alternative technology or a replacement of the
synthetic polymeric additives.
[0005] Laccases are copper-containing enzymes that are known to be
good oxidizing agents in the presence of oxygen and are used for
many other applications, including treatment of pulp waste water,
pulp de-inking, industrial color removal, bleach for laundry
detergents, oral care teeth whiteners. Laccases are being widely
investigated for bio-bleaching wood fiber in pulping process as a
replacement for toxic chemical bleaching reagents. Laccase is also
capable of polymerizing lignin or polyphenols in the wood fiber and
thereby widely investigated as a catalyst or a facilitator to
improve paper dry strength, either with or without mediators or
radical generating chemicals. The likely mechanism for the improved
strength was the crosslinking of lignocellulosic fiber through
lignin oxidation and polymerization. In addition, laccase may also
oxidize other phenolic-containing components such as aromatic side
chains in protein, hemicellulose, cellulosic fiber, etc. under
specific radical-assisted conditions, to provide functional groups
that interact with each other to give paper strength properties.
Advantageously, the actions of laccase on lignin and other
functional groups generally have no adverse effect on fiber quality
such as fiber length under conventional papermaking conditions.
[0006] U.S. Pat. No. 6,207,009 disclosed a process for producing
paper or paperboard from mechanical pulp in which the pulp is
treated with a phenol-oxidizing enzyme, particularly laccase and
peroxidase, after mechanical refining of the pulp has been
completed. The resulting paper exhibits an increased strength
relative to paper produced from untreated pulp. The prior art did
not mention any synergistic effect of laccase with lipase and
cationic polymers for recycled lignocellulosic fiber. Similarly,
U.S. Pat. No. 6,610,172 claimed a process for producing paper
materials having improved wet strength. This process involves (a)
preparing a suspension of unbleached or semi-bleached chemical or
semichemical pulp or pulp from recycled fibers; (b) treating the
pulp with a phenol-oxidizing enzyme, e.g., laccase, and a mediator;
and (c) de-watering the treated pulp in a papermaking machine to
make paper. U.S. Pat. No. 5,603,804 described a process for
producing linerboard or corrugated medium using the oxidase-treated
pulp. The pulp is unbleached Kraft pulp, neutral sulfite
semichemical pulp, or recycled pulp from old corrugated containers
or old news print. The oxidases include laccase, or catechol
oxidase, or bilirubin oxidase.
[0007] US Patent Application No. 20140116635 described a method of
making paper or paperboard having enhanced dry strength using a
laccase or a cellulase enzyme and a cationic water-soluble polymer.
The prior art did not disclose any synergistic effect of laccase
with lipase and cationic polymers on OCC recycled fiber.
[0008] Lipase or esterase has been commercially used for removing
stickies or pitches adhered on the fiber surface in papermaking.
Stickies content varies with fiber type and paper mill systems, and
it poses a major problem to recycled paper mills, particularly to
the Asian or European linerboard mills that routinely use poor
quality recycled OCC. Not only do hydrophobic stickies or pitches
accumulated on the process machinery to reduce productivity and/or
deposit on paper products to lower paper product quality, but also
do those hydrophobic organic contaminants interfere with cellulosic
fiber-fiber interaction and thereby reducing paper strength. In
addition, those hydrophobic contaminants on fiber surface could
prevent enzymes and chemical additives from accessing to fiber
surface for reaction or interactions, and reduce the efficiency of
these reagents.
[0009] US Patent Application No. 20070261806 disclosed methods of
treating pulp stocks with an enzyme formulation containing one or
more oxidative enzymes, to reduce pitch deposition. It described
that the pulp stock is treated with an enzyme formulation
containing laccases, peroxidases, esterases, and/or combinations
thereof. The enzyme formulations may also contain a laccase
mediator and/or a dispersant. The enzyme formulation can be applied
at any of several locations during the pulping and/or papermaking
process, but typically applied as a solution to the pulp stock. The
prior art did not discuss the effect of a cationic polymer on
laccase and esterase performances, and did not disclose any effect
of the formations on paper dry strength property.
[0010] Cationic polymers could be used to blend with enzyme to
improve enzyme stability and accessibility of the enzyme to
cellulosic fiber surface via their fixative property. It could also
benefit in fiber retention and COD reduction in recycled paper
mills. Those benefits have been proved in the lab and also in many
commercial practices.
[0011] U.S. Pat. No. 8,454,798 disclosed a method for making paper
or paper board by applying a composition containing enzyme and
cationic coagulant to papermaking pulp prior to paper forming.
However, this prior art did not disclose any synergistic effect of
laccase, esterase and cationic polymers on paper dry strength
property.
[0012] US Patent Application 20140116653 disclosed a method of
making paper or paperboard having enhanced dry strength using an
enzyme and a polymer including at least one of a cationic
water-soluble polymer and an amphoteric water-soluble polymer. The
prior did not disclose any information on effect of esterase or
lipase on paper strength.
[0013] It is known in the art that cationic polymer can be used in
combination with enzyme for papermaking uses. Cationic polymers are
used together with enzymes for stickies control and strength
applications. Those cationic polymers includes
poly(diallyldimethylammonium chloride), poly(DMA-Epi) polyamine,
polyaminoamide derivatives and polyvinylamine derivatives etc.
However, not all the cationic polymers would benefit enzymes
performance or stability. As matter of a fact, many cationic
polymers reduce or deactivate activity of the enzymes such as
laccase and lipase. Polyvinylamine and glycoxylated PAM may
covalently react and crosslink enzyme to deactivate the enzyme
activity completely. Simply combining an enzyme with a cationic
polymer is not a solution to all.
[0014] The current method provides a dry strength composition for
papermaking to improve dry strength properties of a paper product
and also improve the efficiency of the papermaking process. It has
been discovered that a combination of laccase and lipase together
with cationic polymer with or without a laccase activator provides
for synergistic effects in papermaking and produces a paper product
with improved dry strength properties. More specifically, the
current method relates to the use of a composition to improve dry
strength properties of a paper product by treating a pulp furnish
containing lignocellulosic unbleached fiber and/or recycled brown
stock.
[0015] In the current composition, laccase serves as an enzyme to
polymerize lignin via oxidization, lipase catalyzes breakdown of
organic stickies and pitches on fiber surfaces and improves
accessibility of laccase and the fiber to fiber binding
interaction. The cationic polymers help in dispersing stickies,
stabilizing the laccase and lipase and improves fiber retention.
When laccase and lipase were used in combination with a cationic
polymer, a synergetic effect was observed. Thus, the invention
provides a three-component dry strength composition for use in
papermaking application.
BRIEF SUMMARY OF THE INVENTION
[0016] Provided is method of making a paper and paper products
using a laccase, lipase, cationic fixative polymer composition as
an additive to a lignocellulosic suspension. More particularly, the
current method relates to the use of a laccase, lipase and cationic
fixative polymer formulation or composition to improve dry strength
properties of a paper product made primarily of unbleached
lignocellulosic fibers and/or recycled brown stock. The dry
strength composition includes, in addition to at least one cationic
fixative polymer, at least one laccase having a laccase activity of
at least 12 LAMU and at least one lipase having a lipase activity
of 0.1 to 10 KLU per kilogram (kg) of dry fiber. The addition of
the dry strength composition to the lignocellulosic suspension can
be performed prior to, during, or after mechanical refining.
[0017] In the present application, it is believed laccase is an
active ingredient that specifically catalyzes the oxidation of
lignin, resulting in polymerization of lignin molecule. The laccase
may also catalyze the oxidation of other phenolic components or
carbohydrates under specific conditions. The lipase of the
composition can catalyze the hydrolysis of the wood pitches such as
fatty ester to enhance accessibility of laccase to fiber surface,
or the hydrolysis and removal of stickies contaminants such as
polyvinyl acetate from fiber to help improve fiber binding
property. The three component dry strength composition of the
current method provides improved and enhanced performances of paper
dry strength relative to the use of one or two of the individual
components alone. The present composition can also reduce organic
contaminants and improves turbidity of white water in papermaking
process. As used herein, enzyme composition is the combination or
mixture of one or more enzymes. By "dry strength composition" it is
meant the combination or mixture of laccase, lipase and cationic
fixative polymer.
[0018] Examples of laccases that can be used in the current method
are NS51003 and NS51002 from Novozymes (Bagsvaerd, Denmark); the
optional laccase activator can be selected from copper sulfate,
ascorbic acid and salicylic acid; lipases such as StickAway.RTM. or
Resinase.RTM. A2X from Novozymes (Bagsvaerd, Denmark), and cationic
fixative polymer such as those available from Solenis LLC
(Wilmington, Del., USA) including Zenix DC.RTM. 7429 and Zenix.RTM.
DC7479.
[0019] It should be noted that copper ion may be important for
laccase's catalytic activity or enzyme stability. Laccase from a
commercial sources could lose its activity when the copper ion is
stripped away from the tertiary structure of a laccase protein. It
was discovered that laccase can lose its activity quickly upon
dilution with water, especially at elevated temperatures. This may
be explained by the possibility that the copper ion is released
from laccase when the enzyme solution is diluted. It was also
discovered that the addition of a small amount of copper sulfate to
a laccase formulation helped maintain the laccase activity upon
dilution. With additional copper ion in the formulation, the
equilibrium of copper ion shifts to the laccase protein so the
tertiary structure of the enzyme is maintained in a stable form.
Other ingredients of the dry strength composition may also extract
the copper ion away from laccase so additional copper sulfate may
be needed for the enzyme composition to maintain laccase activity.
It was found that activity of laccase improved significantly when
the copper sulfate was added to the enzyme composition in the range
of 0.05 to 0.1 wt. %. However, when the copper level was further
increased to 0.5 wt. %, the laccase lost some of its original
activity.
The dry strength composition used in the current method is an
aqueous formulation, typically containing up to 95% of water and
5-50% of other non-aqueous components.
[0020] In one embodiment of the dry strength composition, the
active content of wherein the laccase content is from about 3 wt. %
to about 40 wt. % and can be about 10 wt. % to about 25 wt. % by
total weight of the composition; the lipase content is from about 1
wt. % to about 80 wt. %, can be from about 3 wt. % to about 40 wt.
% and may be from about 5 wt. % to about 20 wt. % by total weight
of the composition; and the cationic fixative polymer content can
be from about 2 wt. % to 50 wt. %, can be from about 5 wt. % to
about 40 wt. %, and may be from about 7% to about 20% by total
weight of the composition.
[0021] Laccase alone or in combination with a cationic fixative
polymer, may be used in papermaking processes to improve paper
properties. However, not all the cationic fixative polymers are
compatible with laccase. It was found through laccase assays that
some cationic fixative polymers can reduce or even deactivate
laccase NS51003 (a laccase from Novozymes). Those cationic polymers
include polyvinylamine and glyoxalated poly(acrylamide) that may
have covalently reacted and cross-linked with laccase to deactivate
the enzyme activity. It was also discovered that the enzyme
composition of the current method performed better than a
combination of laccase and cationic polymer in providing improved
dry strength to a paper product made from recycled OCC,
particularly from the poor quality OCC that contains lots of
stickies and pitches contaminants.
[0022] The current method also relates to the process of making a
paper product using a dry strength composition of laccase, lipase
and a cationic polymer. In some aspects, a lignocellulosic fiber in
an aqueous solution is formed to produce a pulp slurry. The dry
strength composition is added to the pulp slurry and the slurry is
dewatered and dried to produce the desired paper product. The
lignocellulosic fiber in an aqueous solution as used herein is
described as a pulp slurry, pulp furnish or pulp suspension, all of
which mean the same thing.
[0023] The dry strength composition of the current method can be
formulated at different weight ratios of laccase and lipase
depending on the specific pulp furnish. In general, an enzyme
composition with higher weight ratio of laccase to lipase gave
better strength results for an unbleached virgin fiber or a good
quality old corrugated container (OCC) furnish having Canadian
standard freeness (CSF) higher than 500, while the enzyme
composition with higher ratio of lipase vs. laccase gave better
strength results for a poor quality recycled OCC furnish with
freeness less than 400 CSF.
[0024] The dry strength composition of the current method may be
also used to reduce organic contaminants in papermaking process and
improve papermaking productivity. The cationic fixing polymer is
effective in interacting with anionic trash, dispersing stickies
and pitch particles, and helping improve fiber-to-fiber interaction
and flocculation which could result in better drainage. It was
found that the treatment of the recycled fiber with the enzyme
composition had no negative effect on fiber yield of virgin
unbleached fiber, and the enzyme composition improved fiber
retention and white water turbidity of a recycled OCC furnish.
[0025] The enzyme compositions have shown synergistic effect in
improving laccase activity and papermaking performance for enhanced
dry strength properties of paper product made from lignocellulosic
material, particularly recycled OCC fibers.
DETAILED DESCRIPTION OF THE INVENTION
[0026] The current method relates to paper products having improved
dry strength. More particularly, the method relates to a
composition for making a paper product that comprises laccase,
lipase, cationic fixative polymer and optionally laccase activity
modifiers or activators wherein the laccase content is from about
wherein the laccase content is from about 3 wt. % to about 40 wt. %
and can be about 10 wt. % to about 25 wt. % by total weight of the
composition; the lipase content is from about 1 wt. % to about 80
wt. %, can be from about 3 wt. % to about 40 wt. % and may be from
about 5 wt. % to about 20 wt. % by total weight of the composition;
and the cationic fixative polymer content can be from about 2 wt. %
to 50 wt. %, can be from about 5 wt. % to about 40 wt. %, and may
be from about 7% to about 20% by total weight of the
composition.
[0027] In other aspects, the current method relates to the use of
enzymes to improve dry strength properties of a paper product. The
method relates to the addition of a composition to a pulp furnish
or suspension, such as a pulp furnish containing unbleached fibers
or recycled brown stock, wherein the composition comprises a
laccase with an activity of at least 12 LAMU and a lipase having a
lipase activity of 0.1 KLU per Kg to 10 KLU per Kg of dry fiber,
and wherein the enzymes are added to the papermaking process either
before, during or after mechanical refining in a papermaking.
[0028] The laccase of the current method may be derived from
microbial, fungal, or other sources. It may furthermore be produced
by recombinant techniques. The laccase of the current method can be
from a commercial source, for example, NS51003 and NS51002 from
Novozymes (Bagsvaerd, Denmark).
[0029] The laccase of the current method can also include enzymes
that possess laccase activity based on current assay methods. The
activity of the laccase used in the Examples below were determined
using syringaldazine as the substrate or by the ABTS assay.
[0030] Examples of enzymes containing laccase activity include, for
example, laccase (EC 1.10.3.2), catechol oxidase (EC 1.10.3.1),
mono-phenol monooxygenase (EC 1.14.99.1), bilirubin oxidase (EC
1.3.3.5), and ascorbate oxidase (EC 1.10.3.3). These can be used
alone or in combination with one another. The EC (Enzyme
Commission) number is based upon the Nomenclature Committee of the
International Union of Biochemistry and Molecular Biology
(IUBMB).
[0031] In other aspects of the current method, the laccase modifier
or activator can be one or more inorganic or organic compounds,
such as copper sulfate, copper ion salts, other metal ions salts,
and ligands that help activate laccase activity, and also laccase
mediators or activators including ascorbic acid, ascorbate,
salicylic acid, salicylate, nicotinic acid, nicotinate, a hardwood
black liquor, a softwood black liquor, ligno-organosolv, lignin
sulfonate, 2-thiouracil, N-benzylidene-benzylamine, melamine,
ferric chloride, potassium ferricyanide, guanidine, cyanuric acid,
nicotinic acid, pyruvic acid, imidazole, phenol, and mixtures
thereof. The term laccase modifier, laccase mediator, laccase
activator, and laccase enhancer are used interchangeably and relate
to the same compounds.
[0032] In yet another aspect of the current method, the laccase
enhancer can be copper sulfate, ascorbic acid, salicyclic acid and
combinations thereof, at a dosage of from about 0.01 wt. % to about
0.5 wt. % by weight of the total composition. The activity may be
negatively affected by a high level of copper sulfate at >0.5%
based on the total weight of the dry strength composition.
[0033] It should be noted that laccase needs oxygen to be active.
Therefore, effective oxygen and air flow in the papermaking process
helps to improve the enzyme activity and efficiency of the laccase
in the papermaking application.
[0034] In some aspects of the current method, lipases can be
derived from microbial, fungal, or other natural sources. Lipases
can also be produced by a genetic recombinant technique or via
chemical modifications. The enzymes possessing lipase activity
include, for example, tri-alkanoate glycerol lipase, fatty ester
lipase, esterase, phospholipase, or combination thereof.
Commercially available enzymes containing lipase activity include,
for example, Stick Away.RTM. or Resinase.RTM. A2X, Resinase.RTM.
NT, Palatase.RTM. from Novozymes (Bagsvaerd, Denmark), and Lipase
G-1000 from DuPont Industrial Biosciences (Palo Alto, Calif., USA).
The lipase activity in the following examples were determined using
the standard lipase KLU (KLU equals to 1000 lipase Units, defined
in WO 89/04361) or determined by lipase assays described in the
current method.
[0035] The lipases of the current method also include enzymes that
possess catalytic activity of hydrolyzing ester bonds, based on the
assays of the current method. Enzymes, such as proteases and
amidases are known to contain lipase activity and therefore could
be used in the current method.
[0036] In one aspect of the present method, current method the
lipase has high esterase activity as determined by lipase assay
using triacetin as a substrate. This lipase preferably catalyzes
the hydrolysis of hydrophobic polyvinyl acetate to release
hydrophilic polyvinyl alcohol and acetic acid. One lipase is
StickAway.RTM., which possesses strong esterase activity towards
triacetin but also lipase activity towards a fatty ester with a
long chain alkyl group up to C18 carbons.
[0037] When StickAway.RTM. was added to a polyvinyl acetate
contaminated old corrugated container (OCC) suspension, the paper
product made from the treated fiber achieved more than 10%
improvement in strength properties over the control without lipase
treatment (see Table 1).
[0038] It is envisioned any enzymes containing lipase activity
towards short chain alkyl esters can also work to enhance fiber
binding property and paper strength. For example, it was discovered
that Resinase.RTM. A2X worked as well as StickAway.RTM. with North
American OCC furnish (see Table 2).
[0039] In other aspects, the cationic fixative polymers used in the
current method with the laccases and lipases can be selected from
the group consisting of poly(diallyldimethylammonium chloride),
poly(dimethylamine-epichlorohydrin-ethylene diamine), cationic
poly(acrylamide), poly(ethyleneimine), hydrophobically modified
cationic polymers, long chain alkyl glycidyl ether modified
poly(aminoamide), cationic natural products such as, cationic
starch and cationic guar, amphoteric polymers that are net
cationic, and combinations thereof. Other cationic fixative
polymers that can be used in the current method are commercially
available from Solenis LLC, Wilmington, Del., USA, such as Zenix
DC.RTM. 7429, Zenix.RTM. DC7479 and DeTac.RTM. DC786C. The cationic
fixative polymers of the current method can be one or more
papermaking additives such as a dry strength resins, wet strength
resins, flocculants, retention aids, and/or drainage aids. It is
worth noting that a different cationic polymer can be applied to a
papermaking system in combination with the current dry strength
composition to improve overall performance of the papermaking
process. It should also be noted that not all the cationic fixative
polymers are suitable for laccase and some cationic polymers, such
as polyvinylamines and glycoxylated polyacrylamides can reduce or
even deactivate the activity of laccase. For example, a
polyvinylamine based cationic polymer negatively affects activities
of laccase or lipase when the polymer is blended with the enzymes,
but as long as the polymer is not blended directly with the
enzymes, it could be used in combination with the laccase and
lipase enzymes in the papermaking process.
[0040] In some aspects of the current method, the dry strength
composition can be stabilized by one or more compounds selected
from propylene glycol, glycerol, ethylene glycol, sorbitol, lactic
acid, glucose, galactose, maltodextrin, monosaccharides,
oligosaccharides, corn syrup, inorganic salts such as sodium and
potassium chloride, a pH buffer system such as sodium or potassium
phosphates, sodium citric acid, tris(hydroxymethyl)methylamine
(Tris), 4-2-hydroxyethyl-1-piperazineethanesulfonic acid (HEPES);
piperazine-N,N-bis(2-ethanesulfonic acid), and 2 2-(N-morpholino)
ethanesulfonic acid.
[0041] In yet another aspect of the method, the dry strength
composition of the current method includes at least one laccase, at
least one lipase with high esterase activity as determined by the
lipase assay using triacetin as substrate, at least one cationic
fixative polymer selected from poly(diallyldimethylammonium
chloride), poly(dimethylamine-epichlorohydrin-ethylene diamine),
and mixtures thereof, and optionally a laccase activator, such as
copper sulfate, ascorbic acid, salicyclic acid and combinations
thereof.
[0042] The weight ratio of laccase/lipase/cationic polymer of the
dry strength composition of the current method is important for its
performance in papermaking as a strength additive. The ratio of
these three main ingredients of the dry strength composition of the
current method can be changed to a specific range to provide
optimized enzyme activities and stability under specific pH, ionic
strength and temperature conditions. The percentage levels of the
three ingredients also affect laccase and lipase efficiencies of
treating different types of unbleached lignocellulosic fibers to
improve paper dry strength. The dry strength composition of the
current method is an aqueous formulation, typically containing up
to 95% of water and 5-50% of other non-aqueous components. In one
embodiment of the dry composition, the active content of a laccase
is from wherein the laccase content is from about 3 wt. % to about
40 wt. % and can be about 10 wt. % to about 25 wt. % by total
weight of the composition; the lipase content is from about 1 wt. %
to about 80 wt. %, can be from about 3 wt. % to about 40 wt. % and
may be from about 5 wt. % to about 20 wt. % by total weight of the
composition; and the cationic fixative polymer content can be from
about 2 wt. % to 50 wt. %, can be from about 5 wt. % to about 40
wt. %, and may be from about 7% to about 20% by total weight of the
composition.
[0043] The active weight percentage of the laccase and lipase of
the dry strength composition is defined on the basis that the
commercial enzymes are 100% active as they are obtained from a
commercial source. The active percentages of the cationic fixative
polymer and laccase activator of the composition are defined as
non-aqueous parts of these polymers or chemicals of the dry
strength compositions.
[0044] The enzyme composition of the current method exhibited
improved laccase activity relative to the original laccase. The
term "improved laccase stability" is intended to indicate that the
enzyme composition after being stored for a period of time at a
certain temperature, and is subjected to the same standard test
conditions as the original laccase at the same dilution factor,
exhibits less in reduction of the laccase activity compared with
that of the original laccase.
[0045] In the enzyme composition of the current method, lipase
activity was measured using triacetin or tributyrin as substrates
via the titration method as described in the example section. It
was found that the cationic fixative polymer Perform.RTM. PC8229
and/or the laccase NS51003 had no negative effect on the lipase
activity of StickAway.RTM.. The lipase activity of the composition
was relatively stable.
[0046] In some aspects of the current method, the pH of the dry
strength composition can be from about 3 to about 10, can be from
about 4 to about 9, and can be from about 5 to about 8. In still
other aspects of the method, laccase can be optionally mixed with a
laccase activator for 5 to 30 minutes at room temperature followed
by the addition of the lipase and cationic fixative polymer.
However, in other aspects, the ingredients can be added in any
sequence in the process of formulating the composition prior to the
composition being added to the pulp furnish. The pH adjustment of
the formulation can be done at the end of the process with an acid
or an alkali after all the ingredients become a homogenous
formulation. A buffer system may also be used to control the pH of
the enzyme composition within a specific range.
[0047] Physical storage stability is a factor when evaluating the
properties of the dry strength composition of the current method.
The term "good physical stability" of the product is intended to
indicate that the enzyme composition has maintained desired
physical properties in appearance, homogeneity and having no
deteriorated odor. The weight ratio of the cationic fixative
polymer is one of the factors affecting such a stability.
[0048] The laccase enzyme activity of the laccase used in the
current method, was measured by a standard syringaldazine assay as
described in the experimental section. The activity was in the
range from about 200 Laccase Myceliophthora Units (LAMU) to 10,000
LAMU per gram, can be from about 500 to about 5,000 LAMU per gram,
and may be from about 1,000 to 2,000 LAMU per gram. The lipase
activity of the enzyme used in the current method, is defined in WO
89/04361, and was in the range of from about 2 KLU/gram to 50 KLU
per gram (one KLU is equal to 1,000 lipase Units), can be from
about 5 KLU to about 25 KLU per gram, and may be from about 10 KLU
per gram to about 30 KLU per gram. The laccase and lipase
activities of the enzymes used in the dry strength composition may
vary with specific batches of products and the commercial sources
from where the enzyme came from. However, amounts used in the
experiments were calculated based on the assumption of being 100%
active as received.
[0049] In other aspects of the current method, the laccase activity
of the dry strength composition of the current method is normally
in the range of from about 40 LAMU per gram to about 2,000 LAMU per
gram, can be from about 100 LAMU per gram to about 1,000 LAMU per
gram, and may be from about 200 LAMU per gram to about 400 LAMU per
gram. The lipase activity of the lipase used in the current method
is normally in the range of from about 0.1 KLU per gram to about 15
KLU per gram, can be from about 0.25 KLU per gram to about 10 KLU
per gram, and may be from about 0.5 KLU per gram to about 5 KLU per
gram. The enzyme activities of the dry strength composition may be
evaluated under specific pH and temperature conditions with
different enzyme substrates as needed.
[0050] In some aspects of the current method, the dry strength
composition may be used in treating all types of cellulosic fibers,
such as lignocellulosic fiber including bleached, unbleached virgin
fiber, mechanical fiber and OCC recycled fiber. In some aspects of
the current method, the dry strength composition may be used to
treat a mixture of bleached fiber, unbleached virgin fiber and
recycled fiber at a certain fiber mixing ratio. In other aspects,
the dry strength composition of the current method is useful in
providing improved dry strength properties of recycled linerboard
produced in papermaking. The dry strength composition may work
effectively with poor quality recycled fiber from Asian such as
TOCC (Taiwan OCC), COCC (Chinese OCC), EOCC (European OCC), and
better quality AOCC (American OCC) as well as unbleached Kraft
fiber (UBSK). The degree of the improvement in a specific strength
property varies with fiber type and treatment conditions and the
specific enzyme composition.
[0051] It was found that the dry strength composition of the
current method usually provided higher improvement in Ring Crush to
the paper made from a good quality fiber such as AOCC and UBSK
while better performance was observed in dry tensile and Mullen
Burst properties of the paper made from the poorer quality fibers
such as TOCC or COCC or EOCC. In addition, the enzyme composition
having a higher weight ratio of laccase vs. lipase is more
efficient in improving ring crush and other strength properties
than a better quality AOCC and unbleached virgin fiber. The
composition having a higher weight ratio of lipase vs. laccase gave
better results in treating poor quality OCC from Asian and Europe
that contained high levels of stickies and pitches.
[0052] In another aspect of the current method, lignocellulosic
fiber in suspension is treated for at least 0.1 hours with the dry
strength composition wherein the dry strength composition has at
least 12 LAMU of laccase activity and 0.1 to 10 KLU of lipase
activity per Kg of dry fiber and the fiber suspension is at a
temperature of from about 20.degree. C. to about 70.degree. C. and
a pH of from about 4.0 to about 9.0. The treated fiber suspension
can optionally be refined using a mechanical refiner for wood fiber
either prior to or subsequent to the addition of the dry strength
composition. The treated suspension can then be dewatered and dried
to form the desired paper product. The dry strength properties of
the paper product, such as Mullen burst, dry tensile, Ring Crush,
ZDT, etc. are tested and the data normalized based on the basis
weight of the blank sheet with treatment or the control with the
individual ingredients of the enzyme composition.
[0053] In yet another aspect of the current method, the pH of the
treated pulp furnish is from about 3.0 to about 9.0, can be from
about 4.0 to about 8.5 and may be from about 4.5 to 8.0; contact
time of the dry strength composition with pulp furnish is from
about 0.1 hour to about 5 hours, can be from about 0.2 hours to
about 3 hours and may be from about 0.3 to about 2 hours; The
temperature can be in the range of from about 10.degree. C. to
70.degree. C., can be in the range of from about As the stock
temperature, pH and other conditions in a papermaking system varies
with paper machines and specific fibers, the efficiencies of
laccase and lipase in a specific enzyme formulation may vary as
well as their particular performances.
[0054] The enzyme composition of the current method can introduced
into a pulper during the pulping stage, or brought into contact at
any stock storage chest, high consistency chest or other holding
tank. It can also be added into the paper machine white water or,
alternatively, can be applied in the water treatment loops of
virgin or recycling mills to treat wood fiber. An effective
agitation or mixing is needed for the laccase and lipase to have an
effective action on the fiber. Air flow in the papermaking system
is particularly critical for laccase that needs oxygen to be
active. Adding an oxidizing agent, such as oxygen, or hydrogen
peroxide, and other peroxides, or TEMPO reagent, may help improve
laccase efficiency in the oxidation reactions. The pulp consistency
is also a factor for the effectiveness of the treatment by the
enzyme composition. High pulp consistency reduces mass-transfer
efficiency, resulting in non-uniform interactions between the
enzyme composition and fiber. Low pulp consistency decreases the
concentration of the enzymes in the pulp at the same dosage of the
enzyme composition based on dry fiber and reduces enzyme
efficiency. In general, the pulp consistency of the lignocellulosic
fiber treated by the enzyme composition of the current method is in
the range of 0.3% to 5%, preferably in the range of 0.5% to 4%, and
most preferably in the range of 1% to 3%.
[0055] In some aspects of the current method, the laccase, lipase,
the cationic fixative polymer, and optionally laccase activator of
the dry strength composition can be formulated together providing a
stable composition. In other aspects, the three or four ingredients
can be used in any combination, added to the pulp furnish
separately, be added at the same or different points in the
papermaking process, and can be added in any sequence to the pulp
furnish to realize the strength benefits of the composition.
[0056] The improved laccase activity was observed with the
combination of laccase, laccase activator, lipase and cationic
fixative polymer via ABTS laccase assay. The results have revealed
that the cationic fixative polymer improved the laccase activity
and lipase gave further improvement on the laccase activity than
seen with the addition of the cationic polymer alone.
[0057] The dry strength composition of the current method may be
used in combination with other papermaking performance additives to
improve paper product properties, such as cationic, anionic,
amphoteric, a nonionic synthetic compounds and natural polymers.
Examples of compounds suitable for use with the composition of the
current method include, but are not limited to, dry strength
papermaking additives, such as starch, starch derivatives,
polyacrylamide derivatives, guar, poly(vinylamine), contaminant
control detackifiers or fixative detackifiers, such as nonionic or
anionic detackifiers, hydrophobically end-capped poly(ethylene
glycol), poly(vinyl alcohol-vinyl acetate), whey protein, soy
protein, hydrophobic and hydrophilic block copolymers,
hydrophobically modified hydroxyethyl cellulose, wet strength
papermaking additives including, but not limited to
polyethyleneimine, urea formaldehyde resin, epichlorohydrin reacted
poly(aminoamide), starch aldehyde, glyoxalated poly(acrylamide);
flocculants for water treatment; coagulants for water treatment;
drainage aids for papermaking; retention aids for papermaking;
sizing agent for paper products; adhesives; debonders; softeners;
creping adhesives; plasticizers for optimizing resin properties;
and modifiers for optimizing resin properties. Individual
components of any of the above combinations may be applied together
or sequentially in papermaking. Additionally, individual components
listed above may be used in combination or blended together prior
to use to make stable formulations or they can be combined on site
at a paper mill prior to use.
[0058] In some aspects of the current method, the dry strength
composition may be used in combination with one or more other
enzymes such as hydrolases, cellulases, xylanases, proteases,
amylases, hemicellulases, mannanases, pectinases, lyases, such as
pectate lyase, cutinase, oxidoreductases, such as glucose oxidase
and peroxidases, or any combinations thereof. These enzymes can be
used in any form, such as in liquid or solid form. Individual
enzymes or any combinations of different enzymes may be applied
together with the dry strength composition of the current method,
or applied sequentially before or after the addition of the dry
strength composition of the current method. Individual enzymes may
be also blended together with the dry strength composition of the
current method to form a blended composition prior to use.
[0059] An experimental model was established to simulate a real
situation in recycled paper mills. Polyvinyl acetate, as model
stickies, may be coated onto OCC paper at 1-2 weight % (based on
dry wt. fiber) and the coated fiber may be pulped to make a uniform
furnish for the dry strength treatment and the subsequent
papermaking. It was seen that the OCC fiber pulped from the coated
paper had higher paper dry strength than the blank after the OCC
fiber was treated with the enzyme composition of the current method
or a lipase.
EXAMPLES
[0060] The following examples further illustrate the current
method, and they are not intended to be in any way limiting to the
scope of the method as claimed.
Determination of Laccase Activity
[0061] Laccase activity was determined using syringaldazine as a
substrate. In this assay, a laccase containing sample was incubated
with syringaldazine dissolved in methanol under aerobic conditions
in 0.1 molar (M) phosphate buffer at pH 7.5 and 25.degree. C. for
110 seconds. The syringaldazine was oxidized to tetramethoxyl azo
bis-methylene quinone having a molar absorptivity of 65,000 at A540
nanometer (nm). The absorbance was measured at 540 nm for 50
seconds. The standard laccase enzyme unit (LAMU) is the amount of
enzyme which converts lmicromole (.mu.mol) syringaldazine to its
quinone form per minute under the prescribed reaction conditions.
One of the laccases used in the examples below is NS51003 from
Novozymes (Bagsvaerd, Denmark) that has a laccase activity unit no
less than 1,000 LAMU per gram as reported and measured at 1,050
LAMU per gram. The laccase activity can vary with batches, storage
time and storage temperature.
ABTS Laccase Assay for Relative Laccase Activity
[0062] The laccase activity was also determined using 2,
2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) as a
substrate. One unit of activity is equal to the micromole of the
oxidized product from ABTS per min per mg protein at pH 4.0 to 6.0
at 23.degree. C. in an acetate buffer. The extinction coefficient
of the oxidized ABTS had a molar absorptivity of 30,000 at A420 nm.
A diluted enzyme solution (1.5 milliliter (ml)) was added to a
mixture of 1.5 ml ABTS (0.5 millimole (mM)) solution and 1.5 ml of
sodium acetate buffer (1 mM) to initiate the oxidization reaction.
After mixing, incubation was conducted at 23.degree. C., while the
change in absorbance per minute was measured at 420 nm. Two
Aspergillus laccases were used both from Novozymes (Bagsvaerd,
Denmark), to compare with the enzyme compositions. The assay pH was
found to have had an effect on laccase activity. NS51002 alone
worked best at pH 4-5 while NS51003 worked best at pH 5-6.
Lipase Assay to Differentiate Esterase and Lipase for Short Chain
and Long Chain Alkanoate Esters
[0063] Lipase activity was determined using tri-alkanoate glycerol
as a substrate. One unit of activity is equal to a micromole of
alkanoic acid released in 1 minute by 1 gram enzyme at pH 7.0. A
one gram sample of tri-alkanoate glycerol was added to 50 grams of
a 0.2 molar (M) sodium chloride solution containing 10 microliter
(.mu.1) of 1% phenolphthalein in ethanol at 45.degree. C. A lipase
solution (0.01 g) was added to initiate a hydrolytic reaction.
While stirring, the pH was maintained at 7.0 by adding 0.1M NaOH
solution to give a slightly pink color (or using a pH-Stat). The
total amount of NaOH solution consumed in 5 to 10 minutes was used
to calculate the alkanoic acid released in the reaction per minute.
In this type assay, triolein was used as a substrate for the lipase
with activity to hydrolyze long chain alkanoate ester and triacetin
was used as a substrate to measure esterase activity to hydrolyze
short chain alkanoate ester. Tributyrin was also used as a
substrate to measure both lipase and esterase activities. For
example, as measured using triolein and triacetin as the
substrates, StickAway.RTM. had 2.5 times more esterase activity
than Resinase.RTM. A2X when triacetin was used as the substrate
while StickAway.RTM. was only 44% of lipase activity of
Resinase.RTM. A2X when triolein was used as the substrate.
[0064] The enzyme activity was also determined using p-nitrophenol
esters of ethanoate, butanoate, dodecanoate, and hexadecanoate as
substrates. One unit of activity is equal to .mu.mol of
p-nitrophenol released in 1 minute by 1 gram enzyme solution at pH
7.5 and 30.degree. C. Substrate solutions (50 mM) of p-nitrophenol
esters were dissolved in dimethyl sulfoxide prior to addition to
the reaction mixture. The assay was initiated when the substrate
solution was added to 50 mM sodium phosphate buffer (pH 7.5)
solution containing lipase activity. Initial rates of p-nitrophenol
release from the substrates were quantitated by measuring
absorbance at 410 nm with molar absorptivity of 12.2 at pH 7.5.
[0065] One of the lipases used in the current method is
StickAway.RTM. from Novozymes (Bagsvaerd, Denmark) that has the
standard lipase at 16.4 KLU/g (KLU equals to 1,000 lipase Units, as
defined in WO 89/04361). The activity can vary with batches,
storage time and temperature.
Protein Assay
[0066] The protein concentration was determined using the Bio-Rad
Protein Assay Method, which is a dye-binding assay based on the
method of Bradford and involves the addition of an acidic dye to a
protein solution, and subsequent measurement at 595 nm with a
Jenway 6320D spectrometer. Comparison to the bovine serum albumin
(BSA) standard curve provides a relative measurement of protein
concentration. The Bio-Rad protein assay reagent was obtained from
Bio-Rad Laboratories. The protein standard was bovine serum albumin
(BSA).
[0067] The protein assay was used to measure protein content in
percentage of the dry strength composition of the current method
and to determine the specific enzyme activity.
Example 1--Synergetic Effect of Laccase, Lipase and Cationic
Polymer Combination on OCC Paper Strength
[0068] Example 1, demonstrates improvement in Mullen burst and Ring
Crush paper dry strength properties of paper sheets made from 100%
recycled OCC. The OCC medium fiber was pulped in water to 3%
consistency creating a pulp slurry and refined to 320 milliliter
CSF using a valley beater. The resulting pulp slurry was treated
with laccase NS51003, StickAway.RTM. and cationic fixative polymer
Perform.RTM. PC8229, each being added to the slurry individually
and also in combinations at 50.degree. C. for 60 minutes under
effectively stirring. The dosages of the chemicals used for the
treatment were based on the dry fiber in percentage. The
combination of chemicals were mixed together prior to the addition
to the pulp slurry. After the treatment, the pulp slurry was cooled
down to room temperature using an ice water bath. Paper handsheets
having a basis weight of 80 lb./3000 sq. ft. were made on a Noble
and Wood hand sheet machine at pH 7.0. Mullen Burst (TAPPI Test
Method T403) and Ring Crush (TAPPI Test Method T818) were
determined, and expressed as % versus the control in Table I.
TABLE-US-00001 TABLE I Synergetic effect of NS51003, StickAway
.RTM. and Perform .RTM. PC 8229 on OCC paper strength. Laccase
Stick- Perform .RTM. Ring Mullen N551003 Away .RTM. PC8229 Crush
Burst Examples Dose % Dose % Dose % % % Comparative 0.2 0 0 105.1
103.6 example 1-1 Comparative 0 0.2 0 101.0 105.9 example 1-2
Comparative 0 0 0.2 92.5 102.2 example 1-3 Comparative 0.2 0.2 0
104.9 107.5 example 1-4 Comparative 0.2 0 0.2 104.9 109.1 example
1-5 Comparative 0 0.2 0.2 98.2 112.5 example 1-6 Example 1-1 0.2
0.2 0.2 108.6 121.5 Example 1-2 0.1 0.1 0.1 105.4 117.5
[0069] In Table I, NS51003 from Novozymes was the laccase,
StickAway.RTM. was the lipase also from Novozymes and Perform.RTM.
PC8229, a poly(diallyldimethylammonium chloride) from Solenis LLC
was the cationic fixative polymer. The results indicate improved
dry strength performances for the combination of laccase NS51003,
lipase StickAway.RTM. and cationic fixative polymer Perform.RTM.
PC8229 (Example 1-1 and 1-2) in both Mullen burst and Ring Crush
compared with those individual components alone and in all the
other combinations when only two of the three chemicals were used
(Comparative Example 1-1 to 1-6). The dry strength composition
containing the laccase, lipase and polymer (Example 1-1) gave 21.5%
improvement in Mullen Burst over the blank at the same enzyme and
polymer dosages and 17.5% improvement at 50% reduced enzymes and
polymer dosages (Example 1-2). This clearly demonstrates the
synergistic effect of the combination of the three components on
Mullen burst. Dry strength improvement in the Ring Crush test with
the three component system (Example 1-1) provided an 8.6% increase
when compared with the laccase, lipase and polymer being added
independently or in combinations of only two of the chemicals using
the same enzyme and polymer dosages.
Example 2--Formulation Process of the Enzyme Compositions
[0070] Example 2, illustrates a method of preparing the dry
strength composition of the current method using laccase, lipase,
cationic fixative polymer and a laccase activator.
[0071] A laccase, optionally a laccase activator when needed, and a
lipase were added sequentially to water at about 20.degree. C. with
gentle stirring until becoming a homogenous solution. A solution of
the cationic fixative polymer was added to the homogenous solution
over 20 minutes at room temperature. The temperature of the
resulting solution was maintained at about 20.degree. C. and
stirred for 20 minutes and then the pH was adjusted to 7.0 using
HCl or NaOH. The solution was a homogenous brown color. The active
content in weight percentage of the laccase or lipase (also termed
as laccase active' or `lipase active`) of the enzyme composition
was based on the original enzyme at 100% active as it is obtained
from a commercial source. The active content in weight percentage
of the laccase activator or cationic fixative polymer (also termed
as `polymer active`) of the dry strength composition is defined as
the non-aqueous parts of the components of the dry strength
composition. The Bio-Rad protein assay was used on the dry strength
compositions to determine protein concentration of the enzyme
composition. Some of the representative enzyme compositions are
tabulated in Table II.
TABLE-US-00002 TABLE II Formulation of the dry strength
compositions of laccase, lipase and cationic polymers Cationic
Appearance fixative Laccase Appearance after 30 days Examples
Laccase Lipase polymer activator as made At 32-35.degree. C.
Example NS51003, StickAway .RTM. Perform .RTM. None 1-1 33% 33%
PC8229, 33% Example NS51003, StickAway .RTM. Perform .RTM. None
Homogenous No change 2-1 24% 6% PC8229, 20% Example NS51003,
StickAway .RTM. Perform .RTM. CuSO4, Homogenous No change 2-2 24%
6% PC8229, 20% 0.05% Example NS51003, StickAway .RTM. Perform .RTM.
None Homogenous No change 2-3 18% 12% PC8229, 20% Example NS51003,
StickAway .RTM. Perform .RTM. None Homogenous A little 2-4 15% 15%
PC8229, 20% settlement Example NS51003, Resinase .RTM. Perform
.RTM. None Homogenous No change 2-5 15% 15% PC8229, 20% Example
NS51003, StickAway .RTM. Perform .RTM. CuSO4, Homogenous A little
2-6 18% 12% PC8229, 20% 0.05% settlements Example NS51003,
StickAway .RTM. Perform .RTM. None Homogenous No change 2-7 18% 12%
PC8229, 10% Example NS51003, Resinase .RTM. Perform .RTM. None
Homogenous Settlement 2-8 18% 12% PC8229, 40% Example NS51003,
StickAway .RTM. Zenix .RTM. None Homogenous No change 2-9 15% 15%
DC7479, 20% Example NS51003, Resinase .RTM. Perform .RTM. Ascorbic
Homogenous 2-10 18% 12% PC8229, 20% acid 0.5% Example NS51003,
StickAway .RTM. Perform .RTM. Salicylic Homogenous 2-11 18% 12%
PC8229, 20% acid 0.5% Example NS51003, StickAway .RTM. Perform
.RTM. Homogenous 2-12 40% 40% PC8229, 20%
[0072] The compositions in Table II also contain 20% glycerol and
water, unless otherwise noted, to make up 100% in total weight.
Example 1-1 and Example 2-12 do not contain glycerol. Zenix.RTM.
DC7479 is poly(dimethylamine-epichlorohydrin-ethylene diamine), a
cationic fixative polymer from Solenis LLC.
Example 3. Synergy of the Enzyme Composition for Improved Laccase
Activity
[0073] The ABTS laccase assay was used to evaluate the effects of
cationic fixative polymer, lipase and the laccase activator of the
dry strength compositions on laccase activity. The same amount of
laccase active in each composition was used in the assay. In Table
III, the relative activity numbers were determined by normalizing
the values based on that of laccase alone at 100%. The effects of
lipase StickAway.RTM. and cationic polymer Perform.RTM. PC8229 on
the ABTS colorimetric assay were small but were also measured and
included in the calculation.
TABLE-US-00003 TABLE III Effect of additives on Laccase activity
based on Laccase assay Laccase Activity Enzyme Compositions (ABTS
Examples Description Assay) % Comparative Laccase NS51003 only 100
Example 3-1 Comparative Laccase NS51003 104.5 Example 3-2 and
Perform .RTM. PC8229 18:20 blend Example 2-3 Enzyme composition
108.2 Example 2-10 Enzyme composition with 115.5 ascorbic acid
Example 2-11 Enzyme composition with 115.2 salicylic acid Example
3-1 Example 2-3 with 0.1% 107.2 H.sub.2O.sub.2
[0074] As shown in Table III, with 20 parts of Perform.RTM. PC8229
(cationic fixative polymer) formulated with 18 parts of laccase
NS51003 (comparative example 3-2), the laccase activity was
enhanced by 4% over laccase alone (Comparative example 3-1). When
an additional 12 parts of the fixative polymer (Example 2-3) was
added to the composition another 4% improvement in laccase activity
was observed, resulting in an 8% improvement in total activity over
the laccase alone. Ascorbic acid or salicylic acid at 0.5% (Example
2-10, 2-11) in the assay further improved the activity by about 7%
with an overall improvement at 15%. Hydrogen peroxide did not help
improve laccase activity (Example 3-1).
[0075] Copper ion such as that from copper sulfate was found to
improve the activity of laccase alone after the laccase enzyme was
diluted. With 0.05% to 0.1% of copper sulfate, the laccase activity
improved more than 30% while it was negatively affected when the
dosage of copper sulfate was higher than 0.5%. The effect of copper
sulfate in the composition on laccase activity is not
significant.
Example 4--Performance of Enzyme Composition on Dry Strength of
Paper Made from UBSK/TOCC Fiber Mix Via the Pilot Paper Machine
Trial
[0076] Example 4, shows the improvement in dry strength properties
of a paper sheet made from unbleached softwood Kraft (UBSK)/TOCC
fiber mix (25:75) by treating the lignocellulosic fiber with the
dry strength composition of the current method. The UBSK was pulped
and refined to 475 ML CSF using a circle beater and then blended
with TOCC (CSF 300 ML) in the slurry chest at a temperature of
about 50.degree. C. to 60.degree. C. The mixed furnish was
transferred to a machine chest of a pilot paper machine (located at
the Hercules Research Center in Wilmington, Del.) and then treated
with the dry strength composition at 0.4% dosage based on the dry
fiber for 15 minutes at 55.degree. C. with agitation. The treated
furnish or slurry was transferred to a small machine chest and used
to produce paper sheets having a basis weight of 80 lb./3000 sq.
ft. The Mullen Burst and Ring Crush properties of the paper sheets
were measured, normalized and expressed as versus the blank sheet
made from UBSK/TOCC fiber mix at the 50/50 ratio with no dry
strength additive (see Table IV).
TABLE-US-00004 TABLE IV Strength performance of fiber substitution
with the enzyme composition Fiber Enzyme Ring Mullen Examples
composition composition Crush % Burst % Comparative UBSK/TOCC None
100 100 Example 4-1 (50/50) Comparative UBSK/TOCC None 95.2 86.5
Example 4-1 (25/75) Example 4-1 UBSK/TOCC Example 103.3 89.5
(25/75) 2-12
[0077] The UBSK/TOCC fiber mix (50:50) blank was a benchmark in
this pilot paper machine trial (Comparative example 4-1).
Substituting 50% UBSK with TOCC resulted in 5% lower in Ring Crush
and 14% lower in Mullen Burst (Comparative example 4-2). The dry
strength composition of the current method (Example 2-12) had 8%
higher Ring Crush and 3% higher Mullen Burst than the control
without the treatment (Example 4-1). The treated furnish also
achieved 50% UBSK reduction and was 3% higher in Ring Crush.
Example 5--Effect of Mechanical Refining on Enzyme Compositions'
Performance in Paper Dry Strength
[0078] Example 5, shows the improvement in dry strength properties
of a paper sheet made from AOCC by treating the fiber with two dry
strength compositions of the current method either prior to or
after mechanical refining. For the pre-refining experiment, the
pulp slurry was incubated with the dry strength compositions for 1
hour at 60.degree. C., and then refined to 300 CSF using a PFI
mill. For post-refining treatment, the pulp slurry was first
refined to 300 CSF using a PFI mill and then the resulting pulp
slurry was treated with the dry strength compositions. The dosage
difference in the two enzyme compositions was determined based on
approximately equal costs of the two compositions. The treated pulp
furnish was used to make handsheets having a basis weight of 80
lb./3000 sq. ft. The Mullen Burst and Ring Crush of the handsheets
were measured and expressed as % versus the corresponding blanks
for the pre-refining furnish and the post-refining furnish. Results
are summarized in Table V below.
TABLE-US-00005 TABLE V Strength performance of the enzyme
composition on OCC before and after refining Refining Enzyme after
the Mullen Ring Examples composition treatment Dosage Burst % Crush
% Example 5-1 Example 2-3 PFI mill 0.25 105.4 117.2 Example 5-2
Example 2-1 PFI mill 0.3 106.3 110.8 Example 5-3 Example 2-3 No
0.25 102.5 113.3 Example 5-4 Example 2-1 No 0.3 103.1 111.2
[0079] The results show good improvement in Ring Crush (>10%)
with the AOCC furnish whether the dry strength composition was
added to the furnish pre-refining or post refining of the furnish
(Example 5-1 to 5-4). The improvement in Mullen Burst was less but
pre-refining treatment appeared to give better Mullen burst
strength properties at 5% to 6% over the blank (Example 5-1,
5-2).
Example 6--Performance of the Enzyme Compositions with Different
Types of OCC Furnishes
[0080] In this experiment, TOCC and COCC, an OCC recycled fiber
from Asia was used. This recycled fiber is of poor quality and a
CSF<300 ML, while AOCC is a much better quality OCC fiber with
freeness in the range from 400 to 600 ML CSF. The TOCC furnish also
contains a lot of organic stickies and pitches. Handsheet
experiments were done using two dry strength compositions made
according to the current method were evaluated on the poor quality
TOCC and better quality AOCC for dry strength performance. AOCC
furnish was refined to a pulp slurry of 300 ML CSF using a PFI mill
and was then treated with the dry strength compositions. The TOCC
slurry was treated with the dry strength compositions without
mechanical refining. All the treated pulp furnish was used to make
handsheets having a basis weight of 80 lb./3000 sq. ft. The Mullen
Burst, Ring Crush and/or dry tensile of the handsheets were
measured and expressed as % versus the blanks without enzyme
treatment (see Table VI).
TABLE-US-00006 TABLE VI Performance of the enzyme compositions on
TOCC and AOCC Enzyme Dosage Mullen Dry Ring Exam- com- OCC wt. %
Burst Tensile Crush ples position furnish vs. fiber % % % Example
Example TOCC 0 100 100 100 6-1 2-1 0.15 101.2 100.6 106.5 0.3 103.8
105.6 112.2 Example Example AOCC 0 100 100 6-2 2-1 0.1 104.2 108
0.2 106.1 117.5 0.4 107.9 116.4 Example Example TOCC 0 100 100 100
6-3 2-3 0.15 107.5 113.5 103.0 0.3 109.2 115.1 105.5
[0081] Table VI shows the results of a handsheet trial using two
OCC fibers having different paper dry strength properties and two
dry strength compositions. These experiments demonstrated different
performance of the two different enzyme compositions with TOCC. The
enzyme composition with different weight percentages of laccase vs.
lipase (i.e. 18% vs 12% (Example 2-3)) gave better performance in
dry tensile and Mullen burst with TOCC (15% improvement in Mullen
Burst at 0.3% dosage (Example 6-3)) while the dry strength
composition with higher levels of laccase and the weight % of
laccase vs. lipase at 24% to 6% (Example 2-1) had better
performance in Ring Crush, giving 12% improvement at 0.3% dosage
but less improvements in dry tensile and Mullen Burst (Example
6-1).
[0082] Each reference cited in the present application above,
including books, patents, published applications, journal articles
and other publications, is incorporated herein by reference in its
entirety.
* * * * *