U.S. patent application number 11/198294 was filed with the patent office on 2007-02-08 for enzymatic opacifying composition for paper, pulp or paperboard, processes using same and pulp, paper or paperboard produced therefrom.
Invention is credited to Alexandre De Laryssa, Yassin Elgarhy.
Application Number | 20070029059 11/198294 |
Document ID | / |
Family ID | 37716598 |
Filed Date | 2007-02-08 |
United States Patent
Application |
20070029059 |
Kind Code |
A1 |
Elgarhy; Yassin ; et
al. |
February 8, 2007 |
Enzymatic opacifying composition for paper, pulp or paperboard,
processes using same and pulp, paper or paperboard produced
therefrom
Abstract
An organic agent for enhancing opacity in paper, paperboard or
pulp comprises a hydrolase or an oxido-reductase; this enzymatic
opacifying agent overcomes drawbacks associated with traditional
organic and inorganic opacifying agents but also serves to provide
increased strength and reduced porosity in paper and
paperboard.
Inventors: |
Elgarhy; Yassin; (Chomedy,
CA) ; De Laryssa; Alexandre; (St-Bruno, CA) |
Correspondence
Address: |
OGILVY RENAULT LLP
1981 MCGILL COLLEGE AVENUE
SUITE 1600
MONTREAL
QC
H3A2Y3
CA
|
Family ID: |
37716598 |
Appl. No.: |
11/198294 |
Filed: |
August 8, 2005 |
Current U.S.
Class: |
162/72 ;
162/158 |
Current CPC
Class: |
D21H 17/005
20130101 |
Class at
Publication: |
162/072 ;
162/158 |
International
Class: |
D21H 17/02 20070101
D21H017/02 |
Claims
1. In a method of enhancing opacity in a paper composition, in
which an organic opacifying agent is incorporated in the paper
composition, the improvement wherein the organic opacifying agent
comprises an enzyme selected from the group consisting of
hydrolases and oxidoreductases.
2. A method according to claim 1, wherein the paper composition is
a paper or paperboard and wherein the organic opacifying agent is
incorporated in a papermaking pulp slurry and the pulp slurry is
formed into the paper or paperboard.
3. A method according to claim 1, wherein the paper composition is
a papermaking pulp and wherein the organic opacifying agent is
incorporated in a slurry of the papermaking pulp.
4. A method according to claim 1, wherein said enzyme is a
hydrolase.
5. A method according to claim 4, wherein said hydrolase is a
cellulase.
6. A method according to claim 1, wherein said enzyme is an
oxidoreductase.
7. A method according to claim 6, wherein said oxidoreductase is a
laccase.
8. A method according to claim 7, wherein said organic opacifying
agent further comprises a mediator.
9. A method according to claim 1, wherein said enzyme is
incorporated in said paper composition in an amount of 0.00002 to
2%, by weight, catalytic protein based on the oven dry weight of
pulp fibers of said paper composition.
10. A method according to claim 9, wherein said amount is 0.0002 to
0.2%, by weight, catalytic protein based on the oven dry weight of
pulp fibers of said paper composition.
11. An opacifying agent for use in enhancing opacity in a paper
composition selected from paper, paperboard and papermaking pulp,
comprising an enzyme selected from the group consisting of
hydrolases and oxidoreductases.
12. An agent according to claim 11, wherein said enzyme is
associated with at least one surfactant or stabilizing agent.
13. An agent according to claim 11, wherein said enzyme is a
cellulase or a laccase.
14. A papermaking stock comprising: pulp slurry of papermaking
fibers and an organic opacifying agent in an aqueous vehicle; said
organic opacifying agent comprising an enzyme selected from
hydrolases and oxidoreductases.
15. A papermaking stock according to claim 14, wherein said slurry
further comprises at least one papermaking additive selected from
the group consisting of fillers, brighteners and sizing agents.
16. A papermaking stock according to claim 14, wherein said enzyme
is selected from cellulases and laccases, and is present in said
slurry in an amount of 0.00002 to 2%, by weight catalytic protein,
based on the oven dry weight of papermaking fibers.
17. An opacified paper composition comprising papermaking fibers
and an organic opacifying agent, wherein said organic opacifying
agent comprises an enzyme selected from the group consisting of
hydrolases and oxidoreductases.
18. An opacified paper composition according to claim 17, wherein
said enzyme is a hydrolase or laccase, and said enzyme is present
in an amount of 0.00002 to 2%, by weight catalytic protein, based
on the oven dry weight of papermaking fibers.
19. A process of producing paper or paperboard of enhanced opacity
comprising: i) providing a pulp slurry of papermaking fibers, ii)
adding an organic opacifying agent to said slurry, and iii) forming
paper or paperboard from said slurry, wherein said organic
opacifying agent comprises an enzyme selected from hydrolases and
oxidoreductases.
20. A process according to claim 19, wherein said enzyme is a
cellulase or a laccase, and said enzyme is in an amount of 0.00002
to 2%, by weight, catalytic protein based on the oven dry weight of
papermaking fibers.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a composition for use in making
paper, pulp or paperboard; and a process of making paper, pulp or
paperboard employing the composition, especially to add opacity to
the paper, pulp or paperboard and a paper, pulp or paperboard
produced using the composition.
BACKGROUND OF THE INVENTION
[0002] In paper and paperboard manufacture, sheet formation is
generally obtained on wire webs in a wet end from pulp slurry and
is followed by the gradual removal of moisture in a press section
and drier section. A calender section follows the drier section
with the purpose of obtaining a desired finish, for example,
smoothness, thickness or gloss.
[0003] Despite the real advantages of using mechanical action to
impart certain characteristics to the sheet, these advantages are
limited. Complementary solutions for improving even further certain
paper or paperboard characteristics can be applied internally in
the wet end or externally with size-presses or coaters when these
are available. These solutions are related to the use of fillers
and functional additives.
[0004] Fillers are generally white pigments that can be divided
into two major categories: [0005] a) regular fillers having wide
application and cost lower than that of cellulosic fiber, e.g.
kaolin clay, ground calcium carbonate and precipitated calcium
carbonate; [0006] b) specialized fillers having usually lower
volume applications and costs sometimes comparable with or even
higher than cellulosic fiber; Some examples are: anatase titanium
dioxide, rutile titanium dioxide, composite pigments, e.g. clay and
titanium dioxide, PSS (precipitated synthetic silica--silica oxides
and precipitated silicate--aluminum silicate), talc (industrial
grade hydrated magnesium silicate), aluminum trihydrate, calcium
sulfate, natural or precipitated barium sulfate, zinc oxide, zinc
sulfur--surface treatments only, Satin White (calcium
sulfo-aluminate complex)--surface treatments only, urea
formaldehyde resin (organic pigment), plastic pigments (empty or
full spheres)--surface treatments only.
[0007] The advantages brought by fillers in paper or paperboard
manufacture are mostly related to cost reductions, except with some
of the specialized fillers, especially titanium dioxide. The
process disadvantages are however important and concern mostly
wire, felt, doctor blade, refiners abrasion, machine deposits
increase, increased linting dust, breaks related to sheet strength
decrease and filler retention difficulties requiring retention
program solutions.
[0008] On the other hand, the functional advantages, with respect
to final product characteristics, brought by fillers are also
important: optical properties, i.e. brightness and opacity,
improvement, improved printability, better sheet formation,
increased smoothness and improved dimensional stability. The
functional disadvantages are mostly related to increased two
sidedness, reduced rigidity, increased linting and decreased sheet
strength.
[0009] Improving the paper or paperboard characteristics beyond the
mechanical limits of a paper or paperboard machine often requires
the use of fillers for their functional advantages and the use of
functional additives for even better results.
[0010] Examples of functional additives which can improve the sheet
characteristics are dyes and optical brighteners, coating polymers,
wet and dry strength resins, sizing agents, fluorocarbons,
traditional organic opacifying agents and other specialty
additives, while process additives that improve the production
process include biocides, deposit-control agents, felt conditioners
and cleaners, defoamers, and effluent treatments.
[0011] Traditional organic opacifying agents are important
functional additives used to improve the sheet characteristics
obtained with mechanical means and with filler use. Resistance to
water penetration, better printing characteristics, increased
opacity brightness and whiteness, increased bulk and caliper,
better formation, have been investigated and often obtained. Some
process improvements related to reduced abrasion and cost reduction
have also been noticed in some cases.
[0012] The following examples illustrate some of the traditional
organic opacifiers:
[0013] U.S. Pat. Nos. 5,296,024 and 5,292,363 disclose a
composition for enhancing opaqueness in papermaking comprising the
reaction product of a fatty acid and a diamine.
[0014] Different US patents related to U.S. Pat. No. 5,296,024
indicate that the resulting amide of the diamine, which forms the
cationic softener base, is the fatty acid monoamide or the diamide
or a mixture thereof.
[0015] U.S. Pat. No. 5,488,139 describes an opacifier which is a
reaction product of an alkanol amine and a dimerized acid, wherein
the diamine (aminoethylethanol amine) is preferred, in this Patent,
the principal reactant with the amine is a dimerized acid.
[0016] Despite the clear advantages traditional opacifiers bring to
papermaking, functional limitations on their use related especially
to paper sheet strength and porosity have been noticed in mill
conditions.
[0017] A particular category of chemical additives with both
funtional and process applications are enzymes, which are proteins
with catalytic properties.
[0018] The use of enzymes is ecologically interesting, and such
enzymes can generally be applied anywere in the paper, paperboard
or even pulp production. The following examples illustrate some of
the present mill or laboratory applications for enzymes: [0019]
Xylanases--for prebleaching and bleaching pulps, especially Kraft.
[0020] Pectinases and xylanases--for debarking. [0021] Laccases,
proteases--for mechanical pulp refining [0022] Cellulases and
xylanases--for chemical pulp refining [0023] Cellulases--for
recycled pulp refining [0024] Cellulases--for KAPPA number
reduction in Kraft cooking [0025] Xylanases--for brightness
reversion [0026] Cellulases, amylases, xylanases, lipases--for
deinking [0027] Cellulases--for tissue softness [0028]
Laccases--for mechanical pulp strength [0029] Manganese
peroxidases--for chemical pulp strength [0030] Cellulases--for
chemical fibre Tinting reduction [0031] Laccases--for increased
chemical fibre bulk [0032] Cellulases and xylanases--for increased
chemical fibre flexibility [0033] Cellulases--for reduced porosity
and increased fibrilation of chemical fibres [0034] Cellulases and
amylases--for increased drainage [0035] Esterases--for stickies
reduction [0036] Amylases, proteases, levan hydrolase--for paper
machine cleaning [0037] Acetyl esterase, pectinases--for mechanical
pulp white water treatments [0038] Peroxidases, laccases,
catalases--for effluent treatments [0039] Pectinases for cationic
demand reduction in peroxide bleached mechanical pulp
[0040] In the prior art, WO95/27825 discloses a preparation process
for increasing the content of inorganic fillers while maintaining
or increasing the Scott internal bond strength, by addition of a
cellulase type enzyme. Increasing the content of inorganic fillers
is known in the art to be needed for particular applications;
inorganic fillers function as opacifiers.
[0041] Increasing the level of inorganic fillers for the majority
of specific paper grades very often equates into one or more of the
following disadvantages: [0042] Increased paper machine blades
abrasion [0043] Increased paper machine press rolls wear [0044]
Increased paper machine inorganic deposits and breaks [0045]
Increased chemical costs in papermaking (e.g. when TiO.sub.2 is
used) [0046] Increased printer equipment abrasion
[0047] All these reasons justify the use of traditional organic
opacifiers rather than inorganic filleras as opacifiers.
[0048] In the prior art. it was known that increasing the levels of
inorganic fillers favors opacity increase, but also results in
decrease in strength.
SUMMARY OF THE INVENTION
[0049] Surprisingly, while investigating porosity increase
enzymatic applications, it has now been discovered that some
enzymes also improve opacity without the drawbacks associated with
traditional organic opacifiers. The handsheets made with enzyme
treated fibres were often less porous, with increased tensile
strength as compared with the untreated controls; and were much
less porous, and exhibited much higher tensile strength as compared
with the traditional organic opacifier treated handsheets.
[0050] In this invention, the opacity obtained with enzymes as
opacifying agents was higher or similar to that obtained with
traditional organic opacifiers while porosity and strength
properties were clearly improved.
[0051] Although the prior art such as WO95/27825 shows that a
cellulase can increase an internal bond strength of paper, the
particular features of the present invention are absent from prior
art. The prior art contains no showing that enzymes increase sheet
opacity without an increase in the content of opacifying inorganic
fillers.
[0052] The enzymes which function as organic opacifying agents may
be added during the course of paper and paperboard manufacturing
processes; and can also be used in the pulp manufacture stage.
[0053] It is an object of the present invention to provide an agent
that adds opacity to paper, paperboard or pulp to which it is
added.
[0054] It is another object of the present invention to provide an
agent for adding to a pulp slurry of cellulosic fibers to enhance
opacity without adversely affecting other properties.
[0055] It is another object of the invention to provide a method of
enhancing opacity in a paper composition such as paper, paperboard
or papermaking pulp.
[0056] It is yet another object of the invention to provide a
process of producing paper or paperboard of enhanced opacity.
[0057] It is still another object of the invention to provide a
papermaking stock, which stock may be formed into a paper or
paperboard of enhanced opacity.
[0058] It is yet another object of this invention to provide an
opacified paper composition, for example a paper, paperboard or
papermaking pulp of enhanced opacity.
[0059] It is a specific object of the present invention to provide
a process wherein an organic opacifying agent is added to recycled,
deinked or virgin pulp of cellulosic fibers to form a paper,
paperboard or pulp having desirable physical characteristics.
[0060] Still another specific object of the present invention is to
provide a process for adding a composition to pulp slurry of
cellulosic fibers in a papermaking process that results in a paper,
paperboard or pulp having enhanced opacity.
[0061] Another specific object of the present invention is to
provide a paper, paperboard, pulp or pulp slurry having the
desirable characteristic of enhanced opacity.
[0062] In accordance with the invention, there is provided in a
method of enhancing opacity in a paper composition, in which an
organic opacifying agent is incorporated in the paper composition,
the improvement wherein the organic opacifying agent comprises an
enzyme selected from the group consisting of hydrolases and
oxidoreductases.
[0063] In accordance with another aspect of the invention, there is
provided an opacifying agent for use in enhancing opacity in a
paper composition selected from paper, paperboard and papermaking
pulp, comprising an enzyme selected from the group consisting of
hydrolases and oxidoreductases.
[0064] In accordance with still another aspect of the invention,
there is provided a papermaking stock comprising: pulp slurry of
papermaking fibers and an organic opacifying agent in an aqueous
vehicle; said organic opacifying agent comprising an enzyme
selected from hydrolases and oxidoreductases.
[0065] In accordance with yet another aspect of the invention,
there is provided an opacified paper composition comprising
papermaking fibers and an organic opacifying agent, wherein said
organic opacifying agent comprises an enzyme selected from the
group consisting of hydrolases and oxidoreductases.
[0066] In accordance with yet another aspect of the invention,
there is provided a process of producing paper or paperboard of
enhanced opacity comprising: i) providing a pulp slurry of
papermaking fibers, ii) adding an organic opacifying agent to said
slurry, and iii) forming paper or paperboard from said slurry,
wherein said organic opacifying agent comprises an enzyme selected
from hydrolases and oxidoreductases.
DETAILED DESCRIPTION OF THE INVENTION
[0067] The invention employs an organic opacifying agent which
avoids disadvantages associated with traditional inorganic
opacifying agents while providing superior physical properties as
compared with prior organic opacifying agents.
[0068] The organic opacifying agents of the invention comprise a
hydrolase or an oxidoreductase enzyme. A preferred hydrolase is a
cellulose (E.C.3.2.1.4); a preferred oxidoreductase is laccase
(E.C.1.10.3.2).
[0069] Hydrolases are enzymes that catalyse the hydrolysis of a
chemical bond, whereby a molecule is cleaved into two parts by the
addition of a molecule of water. The catalysed reaction would have
the following form: A-B+H.sub.2O.fwdarw.A-OH+B-H
[0070] The chemical bonds cleaved in this way by hydrolysis include
C--O, C--N and C--C bonds or in the case of organophosphorous
hydrolases even P--O, P--F and P--S bonds.
[0071] As shown indirectly in the pulp and paper enzymatic
applications example list hereinbefore, hydrolases are a class of
enzymes that benefit from the presence of an extremely large group
of substrates available for enzymatic action, for example
cellulose, hemicelluloses and many others, in conjunction with the
presence of water in large quantities in the pulp, paper and
paperboard processes.
[0072] Cellulases, in particular hydrolyse cellulose, which is an
unbranched glucose polymer composed of 1,4 glucose units linked by
.beta.-1,4-glycosidic bonds, and is the main component of pulp, by
cleaving the .beta.-1,4-glycosidic bonds. Hydrolases which are
cellulolytic enzymes can be classified into three major types:
[0073] 1.0 ENDOGLUCANASES, hydrolyzing randomly the polymeric chain
(EC 3.2.1.4) [0074] 2.0 EXOGLUCANASES, hydrolyzing the ends of the
chain: [0075] 2.1.1 Cellobiohydrolases, eliberating cellobiose--the
glucose dimer (EC 3.2.1.91) [0076] Cellobiohydrolases I:
hydrolyzing the reducing end [0077] Cellobiohydrolases II:
hydrolyzing the non-reducing end [0078] 2.1.2 Glucanhydrolases,
eliberating directly glucose (EC 3.2.1.74) [0079] 3.0
.beta.-GLUCOSIDASES or cellobiases, acting on cellobiose or soluble
cellodextrins (EC 3.2.1.21).
[0080] As shown indirectly in the pulp and paper enzymatic
applications example list, oxidoreductases are a second class of
enzymes that benefit from the presence of an extremely large group
of substrates available for enzymatic action, for example lignin,
cellulose, hemicelluloses and many others, in the pulp, paper and
paperboard processes.
[0081] Oxidoreductases are enzymes that catalyse the transfer of
electrons from one molecule (oxidant or hydrogen donor or electron
donor) to another molecule (reductant or hydrogen acceptor or
electron acceptor). The catalyzed reation would have the following
form: A.sup.-+B.fwdarw.A+B.sup.-
[0082] Laccases in particular (EC 1.10.3.2), surprisingly catalyse
the oxidation of a large number of different substrates, while
enzymes in general, for example cellulases, are usually substrate
specific. Phenolic lignin units, lignin is an aromatic
heteropolymer of phenyl-propanoid units, many phenolic compounds
(diphenols, polyphenols, different substituted phenols), diamines,
aromatic amines, benzenethiols and some inorganics (e.g. iodine)
are oxidised directly with molecular oxygen as final electron
acceptor through laccase action, the oxygen being reduced to
water.
[0083] Besides the presence of molecular oxygen, laccases may
require organic mediators which are sometimes already present in
the pulp slurry.
[0084] Suitable mediators, by way of example, are
2-2'azinobis(3-ethylbenzthiazoline-6-sulfonate); ABTS
1-hydroxybenzotriazole; HBT N-acetyl-N-phenylhydroxylamine or NHA
violuric acid or VIO N-hydroxybenzotriazole or NHB methyl
3,5-dimethoxy-4-hydroxybenzoate; methyl syringate potassium
octacyanomolybtate; 1-phenyl-3-methyl-pyrazolone sodium;
1-phenyl-3methyl-4-methylamino-pyrazolone-5-N(4)-methanesulfonate;
PPNa 1-(3'sufophenyl)-3-methylpyrazolone-5); and SPP
N-hydroxyphthalimide as well as numerous phenoxazines and
phenotiazines.
[0085] The laccase active site contains four copper atoms. In a
reported mechanism, the separate type 1 copper atom extracts one
electron from the substrate, while the other copper atoms (one type
2 and two type 3) grouped in a trinuclear cluster receive the
electron through presumably a conserved Hys-Cys-His tripeptide.
Once the complete reduction in the trinuclear center takes place it
is followed by the molecular oxygen reduction.
[0086] The organic opacifying agent of this invention is usually
added to bleached wood pulp or recycled paper pulp.
[0087] The organic opacifying agent of this invention can be added
alone or in conjunction with sizing agents, brighteners and other
opacifying agents or any other functional or process additives.
[0088] The organic opacifying agent of this invention can be added
to any pulp slurry, deinked or recycled pulp.
[0089] The amount of the opacifying agent and the other components
added to the pulp slurry depends on the type of pulp slurry to
which the opacying agent is added.
[0090] The opacifying agent of this invention provides an increase
in opacity to the paper, paperboard or pulp and provides an
improved strength and porosity.
[0091] The opacifying agent may be employed in conjunction with a
surfactant and stabilizing agents
[0092] Even though the opacying agent can be applied as a powder,
typically it is dispersed in water for addition to the pulp slurry
and typically is added in an amount of 0.00002% to 2%, preferably
0.0002% to 0.2%, catalytic protein by weight, based on the oven dry
weight of the pulp fibers.
[0093] The dispersion in water typically contains 0.1 to 30%, and
preferably about 1-10%, by weight of the catalytic protein.
[0094] The opacifying agent of the invention is more efficient and
more effective even at lower concentration than traditional organic
opacifying agents.
[0095] The opacifying agent of the invention provides improved
opacity to the treated paper, paperboard or pulp.
[0096] A particular advantage of the present invention is that for
a given amount of inorganic filler, if present, in the paper,
paperboard or pulp, which filler may or may not have opacifying
properties, the opacity is enhanced by the organic, enzymatic
opacifying agent. More especially, it is not necessary to use an
inorganic opacifying agent and it is not necessary to increase the
content of an inorganic filler having opacifying properties in
order to increase the opacity, and which increase in content would
result in loss of strength. The organic, enzymatic opacifying agent
of the invention not only enhances the opacity but also increases
the strength and lowers the porosity.
[0097] An inorganic filler is not required in order to provide
opacity when employing the organic opacity agent of the invention;
and the invention contemplates paper compositions containing the
opacifying agent of the invention and being free of inorganic
filler, although inorganic fillers may be included in the paper
composition for the traditional purpose of reducing the pulp
content, without their necessity to provide an opacifying
function.
[0098] The invention is further illustrated by reference to the
Examples.
EXAMPLES
Example 1
[0099] Laboratory opacity, brightness, porosity and tensile
strength testing were performed with the following materials and
methods:
Pulp Preparation:
[0100] Water deionized at pH 7.0
[0101] Furnish: 400 g a.d. pulp: 10% deinked market pulp (40 g),
25% Softwood Kraft (100 g a.d.), 65% Hardwood Kraft (260 g
a.d.).
Additives:
Traditional organic opacifier (amide of fatty acid and diamine),
Trizym DEO (trademark for a cellulase of Tri-Tex), PCC (without
dispersant), TiO.sub.2 (anatase), anionic PAM retention aid
Apparatus for Pulp Preparation:
[0102] Beater with controlled bedplate (Pile Valley Iron Works)
[0103] British disintegrator
[0104] Canadian standard freeness tester
[0105] 150 microns mesh
[0106] Hotplate (Termolyne Cimarec 2.TM.)
[0107] pH meter (VWR scientific model 8000)
[0108] Thermometer (Fisherbrand)
[0109] Caframo stirrer RZR50.TM.
[0110] 1000 ml beaker
[0111] In all trials (control/amide of fatty acid and
diamine/cellulase) the pulp treatments were made as described
below: [0112] 1) In a first stage refining was performed for the
entire 400 g a.d. of pulp according to TAPPI T 200 om-85 to a
freeness of 300 ml CSF. Following the refining, pulp consistency
was adjusted to 3% by filtration through a 150 micron mesh. [0113]
2) In the second stage 30 g a.d./trial of fibre (1000 g pulp) were
heated and maintained at 55.degree. C. for 20 minutes with
opacifier additions or with no opacifier additions (control) in a
1000 ml beaker on the hotplate, while stirring at 300 rpm. The
opacifier additions were made at 0.2% as is/a.d. fibre for Trizym
DEO (trademark for a cellulase of Tri-Tex) and at 0.2% dry/a.d.
fibre for the traditional organic opacifier (amide of fatty acid
and diamine) [0114] 3) In the third stage 15% PCC (4.5 g dry) and
15% TiO.sub.2 (4.5 g dry) addition was followed by 10 minutes of
stirring while maintaining 55.degree. C. pulp temperature. [0115]
4) In the fourth stage the heating was stopped and the pulp was
diluted to 1% with the addition of 2000 g deionized room
temperature water, followed by 0.1% (0.03 g dry) anionic PAM
addition and 2 minutes stirring at 200 rpm.
[0116] Handsheet preparation for optical testing was made with a
slight modification of TAPPI T 218 om-83 without a dispersion
stage, with conditioning (without preconditioning) according to
TAPPI T 402 om-88 for 5 hours at 23.degree. C. and 51% RH. The
modification aimed at improved monitoring of the effect of fines
and white water recirculation on opacity, concerned reusing three
times the white water resulting from sheet formation and retaining
for testing only each fourth sheet.
[0117] Handsheet preparation for physical testing was made with a
slight modification of TAPPI T 205 om-83, with conditioning
(without preconditioning) according to TAPPI T 402 om-88 for 5
hours at 23.degree. C. and 51% RH. The second modification aimed at
improved monitoring of the effect of fines and white water
recirculation on porosity, concerned reusing three times the white
water resulting from sheet formation and retaining for testing only
each fourth sheet.
[0118] Handsheet printing opacity (ISO standard 2471) and ISO
brightness testing were made in the conditioning temperature and
humidity conditions after 5 hours from the handsheet preparation on
a Technibrite Micro TB-1C.TM..
[0119] Handsheet tensile strength (TAPPI T 220 om-88 and TAPPI T
494 om-88) and the air resistance of paper (TAPPI T 460 om-88) were
tested in the conditioning temperature and humidity conditions
after 5 hours from the handsheet preparation with a MC TEC vertical
tensile tester and a UEC-1012--A densometer tester. TABLE-US-00001
ISO ISO Densometer Tensile Trial Brightness Opacity sec/100 ml
Strength nr. % % air kN/m 1 Control 86.50 80.69 63 4.8 2 amide of
86.88 81.58 55 4.4 fatty acid and diamine 3 cellulase 86.91 82.71
121 5.4
Example 2
[0120] Laboratory opacity, brightness, porosity and tensile
strength testing were performed with the following materials and
methods:
Pulp Preparation:
[0121] Water deionized at pH 7.0
[0122] Furnish: 400 g a.d. pulp: 10% deinked market pulp (40 g),
10% Aspen BCTMP (40 g) 25% Softwood Kraft (100 g a.d.), 55%
Hardwood Kraft (220 g a.d.).
Additives:
[0123] Traditional organic opacifier (amide of fatty acid and
diamine), Trizym DLC (trademark for a laccase of Tri-Tex), PCC
(without dispersant), TiO.sub.2 (anatase), anionic PAM retention
aid
Apparatus for Pulp Preparation:
[0124] Beater with controlled bedplate (Pile Valley Iron Works)
[0125] British disintegrator
[0126] Canadian standard freeness tester
[0127] 150 microns mesh
[0128] Hotplate (Termolyne Cimarec 2.TM.)
[0129] pH meter (VWR scientific model 8000)
[0130] Thermometer (Fisherbrand)
[0131] Caframo stirrer RZR50.TM.
[0132] 1000 ml beaker
[0133] In all trials (control/amide of fatty acid and
diamine/laccase) the pulp treatments were made as described below:
[0134] 5) In a first stage refining was performed for the entire
400 g a.d. of pulp according to TAPPI T 200 om-85 to a freeness of
300 ml CSF. Following the refining, pulp consistency was adjusted
to 3% by filtration through a 150 micron mesh. [0135] 6) In the
second stage 30 g a.d./trial of fibre (1000 g pulp) were heated and
maintained at 55.degree. C. for 20 minutes with opacifier additions
or with no opacifier additions (control) in a 1000 ml beaker on the
hotplate, while stirring at 300 rpm. The opacifier additions were
made at 0.2% as is/a.d. fibre for Trizym DLC (trademark for a
laccase of Tri-Tex) and at 0.2% dry/a.d. fibre for the traditional
organic opacifier (amide of fatty acid and diamine) [0136] 7). In
the third stage 15% PCC (4.5 g dry) and 15% TiO.sub.2 (4.5 g dry)
addition was followed by 10 minutes of stirring while maintaining
55.degree. C. pulp temperature. [0137] 8) In the fourth stage the
heating was stopped and the pulp was diluted to 1% with the
addition of 2000 g deionized room temperature water, followed by
0.1% (0.03 g dry) anionic PAM addition and 2 minutes stirring at
200 rpm.
[0138] Handsheet preparation for optical testing was made with a
slight modification of TAPPI T 218 om-83 without a dispersion
stage, with conditioning (without preconditioning) according to
TAPPI T 402 om-88 for 5 hours at 23.degree. C. and 51% RH. The
modification aimed at improved monitoring of the effect of fines
and white water recirculation on opacity, concerned reusing three
times the white water resulting from sheet formation and retaining
for testing only each fourth sheet.
[0139] Handsheet preparation for physical testing was made with a
slight modification of TAPPI T 205 om-83, with conditioning
(without preconditioning) according to TAPPI T 402 om-88 for 5
hours at 23.degree. C. and 51% RH. The second modification aimed at
improved monitoring of the effect of fines and white water
recirculation on porosity, concerned reusing three times the white
water resulting from sheet formation and retaining for testing only
each fourth sheet.
[0140] Handsheet printing opacity (ISO standard 2471) and ISO
brightness testing were made in the conditioning temperature and
humidity conditions after 5 hours from the handsheet preparation on
a Technibrite Micro TB-1C.TM..
[0141] Handsheet tensile strength (TAPPI T 220 om-88 and TAPPI T
494 om-88) and the air resistance of paper (TAPPI T 460 om-88) were
tested in the conditioning temperature and humidity conditions
after 5 hours from the handsheet preparation with a MC TEC vertical
tensile tester and a UEC-1012--A densometer tester. TABLE-US-00002
ISO ISO Densometer Tensile Trial Brightness Opacity sec/100 ml
Strength nr. % % air kN/m 1 Control 86.11 80.51 52 4.3 2 amide of
86.48 81.38 45 4.0 fatty acid and diamine 3 laccase 86.53 81.59 57
5.1
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