U.S. patent application number 12/160898 was filed with the patent office on 2009-03-12 for chemical pulp treatment compositions and methods.
This patent application is currently assigned to NOVOZYMES NORTH AMERICA, INC.. Invention is credited to Kimberly Bloomfield, Kim Borch, Stefanie McCloskey, Hui Xu.
Application Number | 20090065159 12/160898 |
Document ID | / |
Family ID | 38226487 |
Filed Date | 2009-03-12 |
United States Patent
Application |
20090065159 |
Kind Code |
A1 |
Xu; Hui ; et al. |
March 12, 2009 |
CHEMICAL PULP TREATMENT COMPOSITIONS AND METHODS
Abstract
The present invention relates to compositions and methods for
treating pitch problems in chemical pulp by treating chemical pulp
process water with a combination of a lipase and a peroxide source.
The present invention also relates to compositions and methods for
treating pitch problems in chemical pulp by treating chemical pulp
process water with a lipase, a peroxide source and organic
acid(s).
Inventors: |
Xu; Hui; (Wake Forest,
NC) ; Bloomfield; Kimberly; (Greenville, NC) ;
McCloskey; Stefanie; (Raleigh, NC) ; Borch; Kim;
(Birkeroed, DK) |
Correspondence
Address: |
NOVOZYMES NORTH AMERICA, INC.
500 FIFTH AVENUE, SUITE 1600
NEW YORK
NY
10110
US
|
Assignee: |
NOVOZYMES NORTH AMERICA,
INC.
Franklinton
NC
|
Family ID: |
38226487 |
Appl. No.: |
12/160898 |
Filed: |
February 14, 2007 |
PCT Filed: |
February 14, 2007 |
PCT NO: |
PCT/US2007/062136 |
371 Date: |
August 14, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60773242 |
Feb 14, 2006 |
|
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Current U.S.
Class: |
162/78 |
Current CPC
Class: |
D21C 9/08 20130101; D21H
21/02 20130101 |
Class at
Publication: |
162/78 |
International
Class: |
D21C 3/00 20060101
D21C003/00 |
Claims
1. A method for reducing pitch problems in a chemical pulp,
comprising treating a chemical pulp with a lipase and a peroxide
source in amount effective to reduce pitch problems.
2. The method of claim 1, wherein said treating is performed
before, after or in between bleaching stages.
3. The method of claim 1, wherein said chemical pulp is a Kraft
pulp.
4. The method of claim 1, wherein said chemical pulp is a sulfite
pulp.
5. The method of claim 1, wherein said chemical pulp is bleached
Kraft pulp.
6. The method of claim 1, further comprising the step of preparing
paper, linerboard, corrugated paperboard, tissue, towels,
corrugated containers or boxes from said pulp.
7. The method of claim 1, wherein said lipase is derived from a
strain of Aspergillus, a strain of Achromobacter, a strain of
Bacillus, a strain of Candida, a strain of Chromobacter, a strain
of Fusarium, a strain of Humicola, a strain of Hyphozyma, a strain
of Pseudomonas, a strain of Rhizomucor, a strain of Rhizopus, or a
strain of Thermomyces.
8. The method of claim 1, wherein said lipase is derived from a
strain of Candida.
9. The method of claim 1, wherein said lipase is derived from a
strain of Candida antarctica lipase A or the Candida antarctica
lipase B.
10. The method of claim 1, comprising treating a chemical pulp with
a lipase, a peroxide source and an organic acid.
11. The method of claim 1, wherein peroxide source is hydrogen
peroxide.
12. The method of claim 1, wherein peroxide source is a precursor
of hydrogen peroxide.
13. The method of claim 12, wherein the precursor of hydrogen
peroxide is perborate or a percarbonate.
14. The method of claim 1 wherein the peroxide source is an enzyme
that converts molecular oxygen and an organic or inorganic
substrate into hydrogen peroxide.
15-16. (canceled)
Description
FIELD OF THE INVENTION
[0001] The present invention relates to enzymatic compositions and
methods for treating pitch problems in chemical pulp.
BACKGROUND OF THE INVENTION
[0002] Wood contains about 1 to 10% of pitch or extractives in
addition to its main components cellulose, hemicullose and lignin.
Major components of pitch are fatty acids, triglycerides, sterols,
steryl esters and resin acids, such as, for example, abietic acid.
Pitch causes problems in paper machines by sticking to the rollers
and causing spots or holes in the paper material.
[0003] Various enzymatic processes have been used to treat pitch
problems. WO 00/53843 discloses steryl esterase enzyme preparations
and their use in the manufacture of paper to hydrolyze the steryl
ester part of pitch.
[0004] U.S. Pat. No. 6,066,486 discloses an enzyme preparation
comprising a cholesterol esterase derived from Pseudomonas fragi,
and its use to hydrolyze pulp resin.
[0005] JP 2000080581 discloses the use of certain peroxidases for
the decomposition of abietic acid during pulping or paper making
processes.
[0006] X. Zhang; Pulp & Paper Canada. 101: 3 (2000), page
59-62, discloses studies of the ability of laccase to remove
dissolved and colloidal substances.
[0007] Karlsson et al.: Reactivity of Trametes laccases with fatty
and resin acids; Appl. Microbiol. Biotechnol. (2001) 55: 317-320
discloses experiments in which laccases were used to treat
pitch.
[0008] U.S. Patent application 20030124710 discloses a process for
manufacturing a paper material by treating a papermaking pulp
process water with a fatty acid oxidizing enzyme.
[0009] U.S. Pat. No. 5,356,517 discloses the use of lipases to
hydrolyze triglycerides during peroxy bleaching in the preparation
of chemithermomechanical pulp.
SUMMARY OF THE INVENTION
[0010] The present invention relates to compositions and methods
for treating pitch problems in chemical pulp by treating chemical
pulp process water with a combination of a lipase and a peroxide
source. Although not limited to any one theory of operation, it is
believed that the addition of a lipase and peroxide leads to the
formation of peracids which in turn oxidize unsaturated fatty acids
and resin acids through an expoxidation reaction. The resulting
products are hydrophilic and are readily washed from the pulp,
thereby reducing pitch problems associated with chemical pulp.
[0011] In another embodiment, the present invention relates to
compositions and methods for treating pitch problems in chemical
pulp by treating chemical pulp process water with a lipase, a
peroxide source and an organic acid.
DETAILED DESCRIPTION OF THE INVENTION
[0012] A "paper-making process" refers to a process wherein a
chemical pulp is suspended in water, mixed with various additives
and then passed to equipment for further processing, e.g., in which
the paper, cardboard, tissue, towel etc. is formed, pressed and
dried.
[0013] The term "paper material" refers to products which can be
made out of pulp, such as paper, linerboard, corrugated paperboard,
tissue, towels, corrugated containers or boxes.
[0014] The term "a papermaking pulp" or "pulp" means any chemical
pulp which can be used for the production of a paper material.
[0015] A "chemical pulp" refers to chemical pulp (such as Kraft
pulp or sulfite pulp) or semichemical pulp (SCP). Chemical pulp is
usually manufactured by alkaline cooking whereby most of the lignin
and some hemicellulose components are removed. In Kraft pulping or
sulphate cooking, sodium sulphide or sodium hydroxide are generally
used as principal cooking chemicals. In such pulp, as a result of
the alkaline cooking, the triglyceride part of pitch will be
hydrolyzed into fatty acids and glycerol.
[0016] In a particular embodiment of the use and the process of the
invention, the chemical pulp is a Kraft pulp or a sulfite pulp. In
particular embodiments, the Kraft pulp is bleached Kraft pulp, for
example softwood bleached Kraft (SWBK, also called NBKP (Nadel Note
Bleached Kraft Pulp)), hardwood bleached Kraft (HWBK, also called
LBKP (Laub Hote Bleached Kraft Pulp and)) or a mixture thereof.
[0017] The Kraft pulp to be Seated may be a bleached Kraft pulp,
which may consist of softwood bleached Kraft (SWBK, also called
NBKP (Nadel Holz Bleached Kraft Pulp)), hardwood bleached Kraft
(HWBK, also called LBKP (Laub Holz Bleached Kraft Pulp and)) or a
mixture of these
[0018] The pulp to be used in the process of the invention is a
suspension of chemical pulp. The pulp to be used in the process of
the invention may comprise at least 10%, at least 20%, at least
30%, at least 40%, at least 50%, at least 60%, at least 70%, at
least 80%, at least 90%, at least 95%, or 100% of chemical pulp
(such as Kraft pulp or sulfite pulp). The percentage of chemical
pulp lies within the range of 1-100%, in particular embodiments,
the percentage of chemical pulp (such as Kraft pulp or sulfite
pulp) lies within the range of 1-99%, 2-98%, 3-97%, 4-96%, 5-95%,
6-94%, 7-93%, 8-92%, 9-91%, 10-90%, 15-85%, 20-80%, 25-75%, 30-70%,
40-60%, or 45-55%.
[0019] In accordance with the present invention, chemical pulp
process water is treated with a combination of a lipase and a
peroxide source. Such chemical pulp process water contains pitch
causing components, such as, fatty acids, triglycerides, sterols,
steryl esters and/or resin acids (for example, abietic acid). The
process of the invention is particularly applicable to the
reduction of compounds constituting the pitch during a pulping or
paper-making process, e.g. to avoid pitch troubles.
[0020] Any suitable lipase may be used. Lipases include the enzymes
classified by EC 3.1.1.3. Reference is made to the Recommendations
(1992) of the Nomenclature Committee of the international Union of
Biochemistry and Molecular Biology, Academic Press Inc., 1992
[0021] In a preferred embodiment of the present invention, the
lipase is preferably of microbial origin, in particular of
bacterial, fungal or yeast origin. The lipase may be derived from
any source, including, for example, a strain of Absidia, in
particular Absidia blakesleena and Absidia corymbifera, a strain of
Achromobactor, in particular Achromobacter iophagus, a strain of
Aeromonas, a strain of Alternaria, in particular Alternaria
brassiciola, a strain of Aspergillus, in particular Aspergillus
niger and Aspergillus flavus, a strain of Achromobacter, in
particular Achromobacter iophagus, a strain of Aureobasidium, in
particular Aureobasidium pullulans, a strain of Bacillus, in
particular Bacillus pumilus, Bacillus strearothermophilus and
Bacillus subtilis, a strain of Beauveria, a strain of Brochothrix,
in particular Brochothrix thermosohata, a strain of Candida, in
particular Candida cylindracea (Candida rugosa), Candida
paralipolytica, and Candida antarctica, a strain of Chromobacter,
in particular Chromobacter viscosum, a strain of Coprinus, in
particular Coprinus cinerius, a strain of Fusarium, in particular
Fusarium oxysporurn, Fusahum solani, Fusarium solani pisi, and
Fusarium roseum culmorum, a strain of Geotricum, in particular
Geotricum penicillatum, a strain of Hansenula, in particular
Hansenula anomala, a strain of Humicola, in particular Humicola
brevispora, Humicola brevis var. thermoidea, and Humicola insolens,
a strain of Hyphozyma, a strain of Lactobacillus, in particular
Lactobacillus curvatus, a strain of Metarhizium, a strain of Mucor,
a strain of Paecilomyces, a strain of Penicillium. In particular
Penicillium cyclopium, Penicillium crustosum and Penicillium
expansum, a strain of Pseudomonas in particular Pseudomonas
aeruginosa, Pseudomonas alcaligenes, Pseudomonas cepacia (syn.
Burkholderia cepacia), Pseudomonas fluorescens, Pseudomonas tragi,
Pseudomonas maltophilia, Pseudomonas mendocina, Pseudomonas
mephitica lipolytica, Pseudomonas alcaligenes, Pseudomonas
plantari, Pseudomonas pseudoalcaligenes. Pseudomonas putida,
Pseudomonas stutzeri, and Pseudomonas wisconsinensis, a strain of
Rhizoctonia, in particular Rhizoctonia solani, a strain of
Rhizomucor, in particular Rhizomucor miehei, a strain of Rhizopus,
in particular Rhizopus japonicus, Rhizopus microspore and Rhizopus
nodosus, a strain of Rhodosporidium, in particular Rhodosporidium
toruloides, a strain of Rhodotorula, in particular Rhodotorula
glutinis, a strain of Sporobolomyces, in particular Sporobolomyces
shibatanus, a strain of Thermomyces, in particular Thermomycas
lanuginosus (formerly Humicola lanuginosa), a strain of
Thiarosporella, in particular Thiarosporella phaseolina, a strain
of Trichodema, in particular Trichoderma harzianum, and Trichoderma
reesei, and/or a strain of Verticillium.
[0022] In a preferred embodiment, the lipase is derived from a
strain of Aspergillus, a strain of Achromobacter, a strain of
Bacillus, a strain of Candida, a strain of Chromobacter, a strain
of Fusarium, a strain of Humicola, a strain of Hyphozyma, a strain
of Pseudomonas a strain of Rhizomucor, a strain of Rhizopus, or a
strain of Thermomyces.
[0023] Preferred lipases include the lipases described in U.S. Pat.
No. 6,074,863 and WO 02/055679, Preferred commercial lipases
include Resinase A2X and Resinase NT (Novozymes A/S). In another
preferred embodiment, the lipase is the Candida antarctica lipase A
(CALA) or the Candida antarctica lipase 8 (GALS) (available from
Novozymes A/S)
[0024] As used herein, a "peroxide source" or "hydrogen peroxide
source" refers to hydrogen peroxide itself or components which can
generate peroxide. The hydrogen peroxide source may be added at the
beginning or during the lipase treatment process, e.g., at a
concentration of about 0.001-100 mM, particularly 0.01-50 mM. One
source of hydrogen peroxide includes precursors of hydrogen
peroxide, such as, e.g., a perborate or a percarbonate. Another
source of hydrogen peroxide includes enzymes which are able to
convert molecular oxygen and an organic or inorganic substrate into
hydrogen peroxide and the oxidized substrate, respectively. These
enzymes produce only low levels of hydrogen peroxide. Examples of
enzymes which are capable of producing hydrogen peroxide include,
but are not limited to, glucose oxidase, urate oxidase, galactose
oxidase, alcohol oxidase, amine oxidase, amino acid oxidase and
cholesterol oxidase.
[0025] Although not limited to any one theory of operation, it is
believed that the addition of a lipase and peroxide leads to the
formation of peracids which in turn oxidize unsaturated fatty
acids, resin acids and other pitch components through an
epoxidation reaction. The resulting products are hydrophilic and
are readily washed from the pulp, thereby reducing or eliminating
pitch problems.
[0026] Organic acid(s) may also be added to the pulp, e.g., to
enhance the pitch treatment. Organic acids refer to any organic
substance which contains at least one acidic group. Examples of
organic acids are acetic acid, butyric acid, and linoleic acid. The
concentration of organic acid is preferably between 0.001-500
mM.
[0027] In the case of paper and pulp processing, the process
according to the invention can be carried out at any pulp
production stage. The enzyme can be added to any holding tank, e.g.
to a pulp storing container (storage chest), storage tower, mixing
chest or metering chest. The enzyme treatment is preferably applied
before or after pulp bleach process or in between the pulp
bleaching stages. The enzyme can be added to the circulated process
water (white water) originating from bleaching. In a particular
embodiment of a Kraft pulping process, the enzyme is added during
the brown-stock washing.
[0028] In the present context, the term "process water" can include
water added as a raw material to the paper manufacturing process;
intermediate water products resulting from any step of the process
for manufacturing the paper material; as well as waste water as an
output or by-product of the process. In a particular embodiment,
the process water is, has been, is being, or is intended for being
circulated or re-circulated, i.e., re-used in another step of the
process. The term "water" in turn means any aqueous medium,
solution, suspension, e.g., ordinary tap water, and tap water in
admixture with various additives and adjuvants commonly used in
paper manufacturing processes, in a particular embodiment the
process water has a low content of solid (dry) matter, e.g., below
20%, 18%, 16%, 14%, 12%, 10%, 8%, 7%, 6%, 5%, 4%, 3%, 20% or below
1% dry matter.
[0029] The process of the invention may be carried out at
conventional conditions in the paper and pulp processing. The
process conditions will be a function of the enzyme(s) applied, the
reaction time and the conditions given.
[0030] The enzyme and peroxide should be added in an effective
amount. By the term "effective amount" is meant the amount
sufficient to achieve the desired effect of reducing or inhibiting
pitch components, such as, by degrading or converting such
components into a form which can be more readily removed from the
pulp or pulp process water.
[0031] In a particular embodiment, the dosage of the lipase enzyme
is from about 0.1 mg enzyme protein to about 100.000 mg enzyme
protein (of each enzyme) per ton of paper pulp.
[0032] The enzymatic treatment can be done at consistency, e.g.,
0.5-10% dry substance, in particular embodiments, the consistency
is within the range of 0.5-45; 0.5-40; 0.5-35; 0.5-30; 0.5-25;
0.5-20; 0.5-15; 0.5-10; 0.5-3; 0.5-6; or 0.5-5% dry substance.
[0033] The enzymatic treatment may be carried out at a temperature
of from about 10 to about 100.degree. C. Further examples of
temperature ranges (all "from about" and "to about") are the
following; 20-100, 30-100, 35-100, 37-100, 40-100, 50-100, 60-100,
70-100, 10-90, 10-80, 10-70, 10-60, and 30-60.degree. C., as well
as any combination of the upper and lower values here indicated.
The temperature may be from about 20 to 90.degree. C., or 20 to
95.degree. C., preferably from about 40 to 70.degree. C., or 40 to
75.degree. C.
[0034] The enzymatic treatment may be carried out at a pH of from
about 2 to about 12. Further examples of pH ranges (all "from
about" and "to about") are the following: 3-12, 4-12, 5-12, 6-12,
7-12, 8-12, 9-12, 2-11, 2-10, 2-9, 2-8, 4-10, 5-8 as well as any
combination of the upper and lower values here indicated. The pH
range may be from about 2 to 11, preferably within the range from
about 3-9.
[0035] A suitable duration of the enzymatic treatment may be in the
range from a few seconds to several hours, e.g. from about 30
seconds to about 48 hours, or from about 1 minute to about 24
hours, or from about 1 minute to about 18 hours, or from about 1
minute to about 12 hours, or from about 1 minute to 5 hours, or
from about 1 minute to about 2 hours, or from about 1 minute to
about 1 hour, or from about 1 minute to about 30 minutes. The
reaction time may be from about 10 minutes to 3 hours, 10 minutes
to 10 hours, preferably 15 minutes to 1 hour, or 15 minutes to 2
hours.
[0036] Various additives over and above the enzyme and peroxide
treatment can be used in the process or use of the invention.
Surfactants and/or dispersants are often present in, and/or added
to a papermaking pulp. Thus the process and use of the present
invention may be carried out in the presence of an anionic,
non-ionic, cationic and/or zwitterionic surfactant and/or
dispersant conventionally used in a papermaking pulp. Examples of
anionic surfactants are carboxylates, sulphates, sulphonates or
phosphates of alkyl, substituted alkyl or aryl. Fatty acids are
examples of alkyl-carboxylates. Examples of non-ionic surfactants
are polyoxyethylene compounds, such as alcohol ethoxylates,
propoxylates or mixed ethoxy-/propoxyiates, poly-glycerols and
other polyols, as well as certain block-copolymers. Examples of
cationic surfactants are water-soluble cationic polymers, such as
quartenary ammonium sulphates and certain amines, e.g.
epichlorohydrin/dimethylamine polymers (EPI-DMA) and cross-linked
solutions thereof, polydiallyl dimethyl ammonium chloride (DADMAO),
DADMAC/Acrylamide co-polymers, and ionene polymers, such as those
disclosed in U.S. Pat. Nos. 5,681,862; and 5,575,993. Examples of
zwitterionic or amphoteric surfactants are betains, glycinates,
amino propionates, imino propionates and various
imidazolin-derivatives. Also the polymers disclosed in U.S. Pat.
No. 5,256,252 may be used.
[0037] Also according to the invention, surfactants such as the
above, including any combination thereof may be used in a paper
making process. The amount of each surfactant in such composition
may amount to from about 8 to about 40% (w/w) of the composition.
In particular embodiments the amount of each surfactant is from
about 10 to about 38, or from about 12 to about 36, or from about
14 to about 34, or from about 16 to about 34, or from about 18 to
about 34, or from about 20 to about 34, or from about 22 to about
34, or from about 24 to about 34, or from about 26 to about 34, or
from about 28 to about 32% (w/w).
[0038] It is to be understood that the term enzyme, as well as the
various enzymes and enzyme classes mentioned herein, encompass
wild-type enzymes, as well as any variant thereof that retains the
activity in question. Such variants may be produced by recombinant
techniques. The wild-type enzymes may also be produced by
recombinant techniques, or by isolation and purification from the
natural source.
[0039] In a particular embodiment the enzyme in question is
well-defined, meaning that only one major enzyme component is
present. This can be inferred e.g. by fractionation on an
appropriate Size-exclusion column. Such well-defined, or purified,
or highly purified, enzyme can be obtained as is known in the art
and/or described in publications relating to the specific enzyme in
question.
[0040] The term "applied together with" (or "used together with")
means that the additional enzyme may be applied in the same, or in
another step of the process of the invention. The other process
step may be upstream or downstream in the paper manufacturing
process, as compared to the step in which the papermaking, pulp or
process water is treated with lipase and peroxide source.
[0041] In particular embodiments the additional enzyme is an enzyme
which has protease, xylanase, cutinase, oxidoreductase, cellulase,
endoglucanase, amylase, mannanase, steryl esterase, and/or
cholesterol esterase activity. Examples of oxidoreductase enzymes
are enzymes with laccase, and/or peroxidase activity.
[0042] The term "a step" of a process means at least one step, and
it could be one, two, three, four, five or even more process steps.
Thus, the lipase and peroxide source may be applied in at least one
process step, and the additional enzyme(s) may also be applied in
at least one process step, which may be the same or a different
process step as compared to the step where the lipase and peroxide
source is used.
[0043] The term "enzyme preparation" means a product containing at
least one lipase enzyme. In addition to the enzymatic activity such
a preparation preferably contains at least one adjuvant. Examples
of adjuvants, which are used in enzyme preparations for the paper
and pulp industry, are buffers, polymers, surfactants and
stabilizing agents.
[0044] Any enzyme having protease, xylanase, cutinase,
oxidoreductase, cellulase endoglucanase, amylase, mannanase, steryl
esterase, and/or cholesterol esterase activity can be used as
additional enzymes in the use and process of the invention. Below
some non-limiting examples are listed of such additional enzymes.
The enzymes written in capitals are commercial enzymes available
from Novozymes A/S, Krogshoejvej 36, DK-2880 Bagsvaerd, Denmark.
The activity of any of those additional enzymes can be analyzed
using any method known in the art for the enzyme in question,
including the methods mentioned in the references cited.
[0045] Examples of cutinases are those derived from Humicola
insolens (U.S. Pat. No. 5,827,719); from a strain of Fusarium, e.g.
F. roseum culmorum, or particularly F. solani pisi (WO 90/09446; WO
94/14964, WO 94/03578), The cutinase may also be derived from a
strain of Rhizoctonia, e.g. R. solani, or a strain of Alternaria,
e.g. A. brassicicola (WO 94/03578), or variants thereof such as
those described in WO 00/34450, or WO 01/92502.
[0046] Examples of proteases are the ALCALASE, ESPERASE, SAVINASE,
NEUTRASE and DURAZYM proteases. Other proteases are derived from
Nocardiopsis, Aspergillus, Rhizopus, Bacillus alcalophilus, B.
cereus, B. natto, B. vulgatus, B. mycoide, and subtilisins from
Bacillus, especially proteases from the species Nocardiopsis sp.
and Nocardiopsis dassonvillei such as those disclosed in WO
88/03947, and mutants thereof, e.g. those disclosed in WO 91/00345
and EP 415296.
[0047] Examples of amylases are the BAN, AQUAZYM, TERMAMYL, and
AQUAZYM Ultra amylases. An example of a xylanase is the PULPZYME HC
hemicellulase. Examples of endoglucanases are the NOVOZYM 613, 342,
and 476 enzyme products.
[0048] Examples of mannanases are the Trichoderma reesei
endo-beta-mannanases described in Stahlbrand et ai. J. Biotechnol.
29 (1993), 229-242.
[0049] Examples of steryl esterases, peroxidases, laccases, and
cholesterol esterases are disposed in the references mentioned in
the background art section hereof. Further examples of
oxidoreductases are the peroxidases and laccases disclosed in EP
730641; WO 01/98469; EP 719337; EP 765394; EP 767836; EP 763115;
and EP 788547. In the present, context, whenever an oxidoreductase
enzyme is mentioned that requires or benefits from the presence of
acceptors, enhancers, mediators and/or activators, such compounds
should be considered to be included if not already present Examples
of enhancers and mediators are disclosed in EP 705327; WO 98/56899;
EP 677102; EP 781328; and EP 707637. If desired a distinction could
be made by defining an oxidoreductase enzyme system (e.g. a
laccase, or a peroxidase enzyme system) as the combination of the
enzyme in question and its acceptor, and optionally also an
enhancer and/or mediator for the enzyme in question.
[0050] These are particular embodiments of the present invention:
Use of a lipase and peroxide source for reducing the deposition of
pitch in the paper making process. A process for reducing
deposition of pitch in the paper making process, wherein the
process comprises treating the pulp and/or process wafer with a
lipase and peroxide source. Use of a lipase, peroxide source and
organic acid for reducing the deposition of pitch in the paper
making process. A process for reducing deposition of pitch in the
paper making process, wherein the process comprises treating the
pulp and/or process water with a lipase, a peroxide source and
organic acid.
[0051] The invention described and claimed herein is not to be
limited in scope by the specific embodiments herein disclosed,
since these embodiments are intended as illustrations of several
aspects of the invention. Any equivalent embodiments are intended
to be within the scope of this invention, indeed, various
modifications of the invention in addition to those shown and
described herein will become apparent to those skilled in the art
from the foregoing description. Such modifications are also
intended to fail within the scope of the appended claims. In the
case of conflict, the present disclosure including definitions will
control.
[0052] Various references are cited herein, the disclosures of
which are incorporated by reference in their entireties.
EXAMPLES
Example 1
Deresination of Kraft Pulp Pitch by Candida antarctica Lipase B
(CALB)
[0053] Dammar resin was obtained from Fluka and used as a model
pitch to simulate Kraft pulp pitch. TAED was also obtained from
Fluka. Put 75 mg of Dammar resin in a flask and add 75 mL of Dl
water. Add chemicals or enzymes according to the conditions shown
in Table 1. Stir at ambient temperature overnight. Turbidity of the
solutions was determined by UV-vis at 600 nm.
TABLE-US-00001 Sample ID Chemical/Enzyme Dose per beaker 600 nm 1
Control 0.043 2 CALB 50 mg 0.222 3 Peroxide 25 mg 0.084 4 CALB and
peroxide 50 mg/25 mg 0.847 5 Peroxide and TAED 25 mg/360 mg
0.501
After mixing the samples overnight, it was observed that the lipase
(CALB) and peroxide treated sample turned into milky emulsion
whereas the control sample was still as clear as water with the
resins deposited either at the bottom on the wail of the of the
flask. The turbidity results clearly showed that a combination of
peroxide with lipase could lead to better emulsification of dammar
resin. Peracetic acid generated in situ by peroxide and a bleach
activator (TAED) was also fairly effective, but not as effective as
peroxide and lipase combination.
Example 2
Deresination of Kraft Pulp Pitch by Resinase A2X and Resinase
HT
[0054] The experiment was carried out in the same manner as
illustrated in Example 1 except that the flasks were stirred
overnight at 40.degree. C. The lipases used in this study were
Resinase.RTM. A2X and Resinase.RTM. HT (available from Novozymes
A/S).
TABLE-US-00002 Sample ID Chemical/Enzyme Dose per beaker 600 nm 6
Control 0.104 7 Resinase .RTM. A2X 50 mg/25 mg 0.178 8 Resinase
.RTM. HT 50 mg/25 mg 0.219 9 Resinase .RTM. A2X and 50 mg/25 mg
0.535 H.sub.2O.sub.2 10 Resinase .RTM. HT and 50 mg/25 mg 0.614
H.sub.2O.sub.2
It is evident that both Resinase.RTM. A2X and Resinase.RTM. HT
worked to emulsify the Kraft model pitch.
* * * * *