U.S. patent application number 11/231016 was filed with the patent office on 2006-08-03 for method of preparing modified cellulose pulp.
Invention is credited to Tilmann Busse, Jurgen Engelhardt, Christa Kruger, Jurgen Puls, Bode Saake, Nils Schroder.
Application Number | 20060169432 11/231016 |
Document ID | / |
Family ID | 34933545 |
Filed Date | 2006-08-03 |
United States Patent
Application |
20060169432 |
Kind Code |
A1 |
Schroder; Nils ; et
al. |
August 3, 2006 |
Method of preparing modified cellulose pulp
Abstract
A method of preparing modified cellulose pulp using
arabinoxyolans is described. The method involves contacting, (i) an
arabinoxylan with (ii) a cellulose pulp. The arabinoxylan of the
process is in a form selected from a concentrated solution
comprising arabinoxylan or a suspension comprising arabinoxylan.
Also described are: a modified cellulose pulp prepared according to
the present invention; and a particular arabinoxylan having on its
main chain 5 to 20% arabinose substituents, and less than 5%
4-O-methylglucuronic acid substituents, (the percent weights being
based on the total weight of the arabinoxylan).
Inventors: |
Schroder; Nils; (Bad
Fallingbostel, DE) ; Engelhardt; Jurgen; (Bad
Fallingbostel, DE) ; Kruger; Christa;
(Schneverdingen, DE) ; Busse; Tilmann; (Hamburg,
DE) ; Saake; Bode; (Hamburg, DE) ; Puls;
Jurgen; (Reinbeck, DE) |
Correspondence
Address: |
BAYER MATERIAL SCIENCE LLC
100 BAYER ROAD
PITTSBURGH
PA
15205
US
|
Family ID: |
34933545 |
Appl. No.: |
11/231016 |
Filed: |
September 20, 2005 |
Current U.S.
Class: |
162/175 ;
162/158; 162/182 |
Current CPC
Class: |
D21H 17/22 20130101;
D21H 23/02 20130101; D21C 5/005 20130101 |
Class at
Publication: |
162/175 ;
162/158; 162/182 |
International
Class: |
D21H 17/24 20060101
D21H017/24 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 2, 2005 |
EP |
05002073.4 |
Claims
1. A method of preparing a modified cellulose pulp comprising
contacting, (i) an arabinoxylan, said arabinoxylan being in a form
selected from the group consisting of a concentrated solution
comprising arabinoxylan and a suspension comprising arabinoxylan,
with (ii) a cellulose pulp.
2. The method of claim 1 wherein 0.1 and 40% by weight of said
arabinoxylan is contacted with said cellulose pulp, based on the
total weight of arabinoxylan and cellulose pulp.
3. The method of claim 1 further comprising: incubating the
arabinoxylan with the cellulose pulp at a cellulose pulp
concentration of a positive amount up to 20% by weight, based on
the total weight of arabinoxylan and cellulose pulp, thereby
forming an incubated composition comprising arabinoxylan and
cellulose pulp; and adding at least one paper additive to said
incubated composition.
4. The method of claim 1 further comprising: adding at least one
paper additive, thereby forming a composition comprising
arabinoxylan, cellulose pulp and said additive; and incubating the
composition comprising arabinoxylan, cellulose pulp and said
additive, wherein said cellulose pulp is present in a positive
amount of up to 20% by weight, based on the total weight of
arabinoxylan and cellulose pulp.
5. The method of claim 1 further comprising: providing a paper
making machine comprising a head box; and introducing said
arabinoxylan and said cellulose pulp into the head box of said
paper making machine after contacting said arabinoxylan with said
cellulose pulp.
6. The method of claim 1 further comprising refining a composition
formed by contacting said arabinoxylan with said cellulose pulp in
a refiner.
7. A modified cellulose pulp comprising: cellulose pulp; and 0.1%
to 40% by weight of an arabinoxylan, based on the total weight of
cellulose pulp and arabinoxylan.
8. The modified cellulose pulp of claim 7 wherein the arabinoxylan
comprises, on its main chain: 5 to 20% arabinose substituents; and
less than 5% 4-O-methylglucuronic acid substituents, the percent
weights being based on the total weight of the arabinoxylan.
9. An arabinoxylan comprising, on its main chain: 5 to 20%
arabinose substituents; and less that 5% 4-O-methylglucuronic acid
substituents the percent weights being based on the total weight of
the arabinoxylan.
10. Paper comprising the modified cellulose of claim 1.
Description
CROSS REFERENCE TO RELATED PATENT APPLICATION
[0001] The present patent application claims the right of priority
under 35 U.S.C. .sctn. 119 (a)-(d) of European Patent Application
No. 05 002 073.4, filed Feb. 2, 2005.
FIELD OF THE INVENTION
[0002] The present invention concerns the use of arabinoxylans as
additive in paper production.
BACKGROUND OF THE INVENTION
[0003] The mechanical properties of paper are influenced by a
series of different parameters of a chemical and physical nature.
Several theories to explain the tear resistance properties of paper
have been suggested, most of which emphasise the special relevance
of fibre-fibre bonding. Amongst the most frequently cited is the
theory that includes the factors of interfibre bonding force of the
bonded surface and the length of the fibre.
[0004] It is generally agreed that the hemicelluloses native to the
pulp improves the tear resistance and contributes to the formation
of stronger fibre bonding. Depending upon the raw material and the
pulping method, these hemicelluloses are modified greatly during
pulp preparation and are destroyed to a considerable extent.
[0005] The use of xylans as additive in paper manufacture is known.
Thus Naterova et al. (Papir a celuloza, 41, (7-8), V23-V30, 1986)
describe the addition of 2% maize xylan to packaging paper. In this
way the flexural strength is increased by about 172% by the
addition of 2% xylan.
[0006] DE 44 09 372 A1, U.S. Pat. No. 5,810,972 and WO 2004/031477
A1 describe the addition of highly refined birch pulp and Lenzing
xylan in the range of 0.005 to 0.14% (WO 2004/031477 A1) or 0.15 to
1.5% (U.S. Pat. No. 5,810,972, DE 44 09 372 A1) to tissue products.
A positive effect of the xylans and xylan-rich, highly refined
birch pulp on the softness of the tissue product and the behaviour
of the paper web on the drying drum is described. The breaking
strength was increased by 15 to 73% in the machine way and 17 to
90% transverse to the direction of travel. Allegedly the behaviour
of the dry end was positively influence but not reported
numerically, but assessed according to the experience of the paper
maker.
[0007] In the aforementioned applications the use of xylans from
the raw material wood and its secondary product pulp is discussed.
In particular, the use of acetyl-4-O-methylglucuronoxylan from
deciduous wood and arabino-4-O-methylglucuronoxylan from coniferous
wood is cited. The examples on the use of xylans cites Lenzing
xylan. This product is obtained by alkaline extraction of beech
wood pulp in the viscose process and exhibits only a low degree of
polymerisation of about 35.
[0008] Consequently different xylans have been investigated in
respect of their attributes for the fibre properties or as paper
additive. However, the work cited shows that an improvement in tear
length is associated with a deterioration in other strength
properties or in an unacceptable deterioration in optical
properties.
[0009] There is therefore still the requirement for a
cost-effective paper additive that brings about an improvement in
paper properties, in particular strength, bulk and optical
properties.
SUMMARY OF THE INVENTION
[0010] It has now been surprisingly found that the addition of
arabinoxylans to pulp during paper production brings about a
significant improvement in paper properties. By the use of
arabinoxylan the tear length, the tear resistance and the bulk,
i.e., the volume of the paper, is improved. The improvement in the
bulk improves both the strength properties and the optical
properties of the paper. Surprisingly a significantly greater
improvement of the paper properties is achieved in comparison to
other xylans such as 4-O-methylglucuronoxylans from deciduous wood
or Lenzing xylans.
[0011] In accordance with the present invention, there is provided
a method of preparing a modified cellulose pulp comprising
contacting, [0012] (i) an arabinoxylan, said arabinoxylan being in
a form selected from the group consisting of a concentrated
solution comprising arabinoxylan and a suspension comprising
arabinoxylan, with [0013] (ii) a cellulose pulp.
[0014] In further accordance with the present invention, there is
provided a modified cellulose pulp comprising: [0015] cellulose
pulp; and [0016] 0.1% to 40% by weight of an arabinoxylan, based on
the total weight of cellulose pulp and arabinoxylan.
[0017] There is also provided, in accordance with the present
invention, an arabinoxylan comprising, on its main chain: [0018] 5
to 20% arabinose substituents; and [0019] less that 5%
4-O-methylglucuronic acid substituents the percent weights being
based on the total weight of the arabinoxylan.
[0020] The subject matter of the invention relates in part to the
use of arabinoxylans as additive in paper manufacture.
[0021] The features that characterize the present invention are
pointed out with particularity in the claims, which are annexed to
and form a part of this disclosure.
[0022] These and other features of the invention, its operating
advantages and the specific objects obtained by its use will be
more fully understood from the following detailed description and
accompanying drawings in which preferred embodiments of the
invention are illustrated and described.
[0023] Unless otherwise indicated, all numbers or expressions used
in the specification and claims are understood as modified in all
instances by the term "about."
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a graphical representation of plots of tear and
tensile strengths of pulp samples treated with arabinoxylan;
and
[0025] FIG. 2 is a graphical representation of a plot of specific
volume of pulp versus tensile break strength for samples of pulp
treated with arabinoxylan.
DETAILED DESCRIPTION OF THE INVENTION
[0026] Suitable arabinoxylans are polysaccharides that are present
in, for example, different annual plants and agricultural residues
such as oat husks, straw or maize. The arabinoxylans can be
obtained by different extraction techniques, e.g., with water,
steam or solvents with the aid of the most different of auxiliary
chemicals, as well as by enzymatic isolation and purification
steps. Preferably alkali-extracted arabinoxylans are used,
especially arabinoxylans from oat husks that can be obtained, for
example, by extraction of oat husks with aqueous alkali solution,
separation of the alkaline extract and subsequent precipitation of
the alkaline extract in a precipitation bath of water and a
water-miscible organic solvent A, with the alkaline extract not
neutralised before precipitation.
[0027] The special feature of the arabinoxylans from oat husks in
comparison to xylans from deciduous wood and coniferous wood is
that they have a comparably high number of arabinose substituents
but not the 4-O-methylglucuronic acids occurring in deciduous and
coniferous xylans. In comparison to xylans from pulp such as the
Lenzing xylans, the arabinoxylans exhibit a much higher chain
length.
[0028] Within the context of the present invention arabinoxylans
are understood to be such xylans that bear 5 to 20% (w/w relative
to the whole sample), preferably 7 to 15%, most preferably 8 to 13%
arabinose substituents in their main chain and less than 5%,
preferably less than 2%, most preferably less than 1%
4-O-methylglucuronic acid substituents (chromatographic sugar
determination after acid hydrolysis).
[0029] Arabinoxylans that are obtained by extraction of oat husks
with aqueous alkaline solution with isolation of an alkaline
extract and subsequent precipitation of the alkaline extract in a
precipitation bath of water with a water-miscible organic solvent A
with the alkaline extract not neutralised before precipitation are
particularly preferred. Such arabinoxylans exhibit a chain length
of at least 100 also after a possible bleaching stage. Usually the
chain lengths of these arabinoxylans lie in the range 120 to
240.
[0030] A further subject matter of the invention is a method for
the preparation of cellulose pulps comprised of contact with a
concentrated solution or suspension of an arabinoxylan with pulp or
stock system that contains pulp.
[0031] In one embodiment of the invention the arabinoxylan solution
or suspension is added to the fibre suspension before sheet making.
The action of the arabinoxylan is also carried out in combination
with other paper chemicals which are added to the fibre before,
after or together with the arabinoxylan. In this way the use of
arabinoxylan is advantageous for the most different of products in
the paper industry.
[0032] Other normal paper chemicals are for example wet-strength
agents, fillers, retention agents, fixatives, defoamers,
deaerators, sizing agents, optical brighteners and colorants.
[0033] A homogeneous solution or suspension of the arabinoxylan can
be achieved, for example, by intense mechanical loading such as
stirring, by the effect of temperature or with the help of
chemicals, preferably basic chemicals such as alkali or alkaline
earth hydroxides, preferably NaOH. The concentration of the
arabinoxylan solution or suspension can be varied over a wide range
of 0.1 to 40% (w/w). Preferred is the range of 0.1 to 25% (w/w),
especially preferred is the range from 0.5% to 10% (w/w).
[0034] The arabinoxylan solution or suspension can be incubated
with the pulp and the desired paper auxiliaries and additives in
high pulp density (solids content) of up to 20% before the pulp
enters the headbox of the paper machine. Then by squeezing out the
supernatant solution any unabsorbed chemicals can be used for the
next batch.
[0035] In a further embodiment of the invention the pulp is mixed
with the additives and the arabinoxylan solution or suspension in
any desired sequence in the headbox, that is immediately before
entry into the machine for paper production. The addition of the
arabinoxylan in the headbox usually achieves better results than
the previous incubation with the pulp.
[0036] In a further embodiment of the invention the arabinoxylan
solution or suspension is added to the pulp suspension before the
refinement of the pulp fibres.
[0037] Usually after achieving the optimal quantities no further
increase in strength and bulk is achieved by further increase in
the amount of arabinoxylan in a product formulation. The optimal
amount is dependent upon which other paper auxiliaries are used in
the mass so that that the amount of arabinoxylan used relative to
pulp can be in a wide range of 0.1% to 40% (w/w). Preferably,
however, an amount between 0.5 and 10% arabinoxylan is used.
Usually with the use of paper additives the optimal increase in
strength is achieved at even lower arabinoxylan concentration.
[0038] The invention is illustrated but not limited in the
following by a number of embodiment examples.
EXAMPLES
[0039] Unless otherwise stated in the following examples the
compositions of xylans are given as % w/w relative to the whole
sample, determined by chromatographic sugar determination after
acid hydrolysis.
Example 1
Of the Invention
[0040] An arabinoxylan from oat husks (9.5% arabinose, <1%
4-O-methylglucuronic acid, DP ca. 160) was dissolved in water with
heating with formation of a 5% solution. 20 g coniferous sulfite
pulp was suspended in water and treated with the xylan solution in
the amounts given in Table 1. For experiments with higher amounts
of xylan solution correspondingly lower amounts of water were used
in each case for suspension of the pulp. After addition of the
xylan suspensions the pulp density was 7.1% in each case. The
experimental batches were all incubated for 2 h at 50.degree. C.
After incubation the pulp was filtered off through a nutsch.
[0041] The pulp was refined for 2.5 min in a Jokro mill in
accordance with ISO 5264-3 and laboratory sheets produced in
accordance with ISO 5269-2 (rapid Kothen method). Testing for
strength was carried out in accordance with ISO 1974 (DIN EN
21974). TABLE-US-00001 TABLE 1 Amount of arabinoxylan in % (w/w)
rel. to pulp Tear length (m) 0 2734 (reference) 7.5 3473 22.5 3935
37.5 4199
[0042] The data in Table 1 show that in comparison with the
reference pulp without xylan the pulp treated with arabinoxylan
from oat husks exhibited considerably higher strength. The tear
lengths increased with increasing xylan amounts. The greatest
increase in tear length by addition of arabinoxylan from oat husks
is 1465 m.
Example 2
Comparison Example
[0043] A 4-O-methylglucuronoxylan from birch wood (no arabinose
side chains, 8.8% molar ratio 4-O-methylglucuronic acid relative to
xylose units, determined by .sup.1H NMR, DP ca. 95) was dissolved
in water with heating as 5% solution. 20 g coniferous sulfite pulp
was suspended in water and treated with the xylan solution. For
experiments with higher amounts of xylan solution correspondingly
lower amounts of water were used to suspend the pulp. After
addition of the xylan suspensions the pulp density was 7.1% in each
case. The experimental batches were each incubated for 2 h at
50.degree. C. After incubation the pulp was filtered off through a
nutsch.
[0044] The pulp was refined for 2.5 min in a Jokro mill in
accordance with ISO 5264-3 and laboratory sheets produced in
accordance with ISO 5269-2 (rapid Kothen method). Testing for
strength was carried in accordance with ISO 1974 (DIN EN 21974).
TABLE-US-00002 TABLE 2 Amount of 4-O- methylglucuronoxylan in %
(w/w) rel. to pulp Tear length (m) 0 2734 (reference) 7.5 2983 22.5
3126 37.5 3189
[0045] The data in Table 2 show that the 4-O-methylglucuronoxylan
from birch wood can bring about only a very small increase in
strength. The action of this xylan is less that 31% of the action
of arabinoxylan from oat husks.
Experiment 3
Comparison Example
[0046] The Lenzing xylan from beech wood pulp (no arabinose side
chains, 1% 4-O-methylglucuronic acid, DP ca. 35) was dissolved in
water with heating as 5% solution. 20 g coniferous sulfite pulp was
suspended in water and treated with the xylan solution. For
experiments with higher amounts of xylan solution correspondingly
lower amounts of water used to suspend the pulp. After addition of
the xylan suspensions the pulp density was 7.1% in each case. The
experimental batches were incubated for 2 h at 50.degree. C. After
incubation the pulp was filtered off through a nutsch.
[0047] The pulp was refined for 2.5 min in a Jokro mill in
accordance with ISO 5264-3 and laboratory sheets produced in
accordance with ISO 5269-2 (rapid Kothen method). Testing for
strength was carried out in accordance with ISO 1974 (DIN EN
21974).
[0048] The data in Table 3 show that the "Lenzing xylan" from beech
wood pulp can bring about only a very small increase in strength.
The action of this xylan is less that 36% of the action of
arabinoxylan from oat husks. TABLE-US-00003 TABLE 3 Amount of
Lenzing xylan in % (w/w) rel. to pulp Tear length (m) 0 2734
(reference) 7.5 3010 22.5 3000 37.5 3260
Example 4
[0049] An arabinoxylan (9.5% arabinose, <1% 4-O-methylglucuronic
acid DP ca. 160) from oat husks was dissolved in water with heating
as 5% solution. A coniferous sulfite pulp was then refined for 2.5
min. in a Jokro mill in accordance with ISO 5264-3 and laboratory
sheets prepared in accordance with ISO 5269-2 (rapid Kothen
method). The arabinoxylan solutions were in each case added to the
pan which is used for portioning the suspension for the individual
laboratory sheets. In each pan 16 g pulp were equalised in each
case in a total liquid of 6.67 l with a pulp density of 0.24%. The
respective amounts of arabinoxylan solution was added. After 5 min
portioning and preparation of the laboratory sheets was carried
out. All experiments were carried out at room temperature. Testing
for strength was carried out according to ISO1974 (DIN EN 21974).
TABLE-US-00004 TABLE 4 Influence of arabinoxylan from oat husks on
the tear length of coniferous sulfite pulp. The arabinoxylan
treatment took place at a pulp density of 0.24% after refinement of
the pulp. Amount of arabinoxylan % (w/w) rel. to pulp Tear length
(m) Reference 2830 4.7 3759 9.4 4216 28.1 4031
[0050] The tear length can be improved by more than 1000 m by the
addition of arabinoxylan from oat husks compared to the reference.
With this method of addition the increases in strength can be
achieved with low usage of arabinoxylan.
Example 5
[0051] An arabinoxylan from oat husks (9.5% arabinose, <1%
4-O-methylglucuronic acid DP ca. 160) was dissolved in water with
heating as 5% solution. A coniferous sulfite pulp was then refined
for 2.5 min. in a Jokro mill in accordance with ISO 5264-3 and
laboratory sheets prepared in accordance with ISO 5269-2 (rapid
Kothen method). The xylan solutions were in each case added to the
pan which is used for portioning the suspension for the individual
laboratory sheets. In each pan 16 g pulp were equalised in each
case in a total liquid of 6.67 l with a pulp density of 0.24%. A
cationic polyamide-epichlorhydrin resin was added as paper
auxiliary and stirred into the suspension for 5 min. The dosage of
the paper additive corresponded constantly to a charge density of
0.013 meq/g pulp in all experiments carried out. Next the
respective arabinoxylan solution was added. After 5 min portioning
and preparation of the laboratory sheets was carried out.
[0052] All experiments were carried out at room temperature.
Testing for strength was carried out according to ISO1974 (DIN EN
21974). TABLE-US-00005 TABLE 5 Influence of arabinoxylan from oat
husks on the tear length of coniferous sulfite pulp with
concomitant use of a paper additive. The arabinoxylan treatment
took place at a pulp density of 0.24% after refinement of the pulp.
Arabinoxylan with paper Amount of xylan additive % (w/w) rel. to
pulp Tear length (m) Reference 3944 0.09 3992 0.93 4698 2.3 5486
4.7 5629 7.0 5710 9.4 5728
[0053] The tear length can again be significantly increased by the
addition of arabinoxylan compared to the reference. It can be
clearly seen from the reference that through the use of the paper
additive the strength generally lies at a higher level. In regard
to the effect of the arabinoxylan a synergistic effect emerges in
the interaction with the paper additive. The increases in the tear
length are now up to as much as ca. 1800 m. The higher increases in
strength are even effective at lower amounts of arabinoxylan than
in the experiments without paper additive.
Example 6
[0054] An arabinoxylan from oat husks (9.5% arabinose, <1%
4-O-methylglucuronic acid, DP ca. 160) was dissolved in water with
heating as 5% solution. A beech wood sulfite pulp was then refined
for 2.5 min, 5 min, 10 min, 15 min and 20 min in a Jokro mill in
accordance with ISO 5264-3 and laboratory sheets were prepared in
accordance with ISO 5269-2 (rapid Kothen method). The arabinoxylan
solutions at 9.4% (relative to pulp) were in each case added to the
pan which is used for portioning the suspension for the individual
laboratory sheets. In each pan 16 g pulp were equalised in each
case in a total liquid of 6.67 l with a pulp density of 0.24%. 5
Min after addition of the arabinoxylan solution portioning and
preparation of the laboratory sheets was carried out. All
experiments were carried out at room temperature. Testing for
strength was carried out according to ISO1974 (DIN EN 21974). Light
scattering coefficients were determined according to Instruction
SCAN C 27:76.
[0055] The experiments showed that not only the tensile strength of
the pulp was increase by arabinoxylan addition, but also the tear
strength. The tear-tensile plot allows combined viewing of the
tensile strength and tear strength of all samples from the
refinement series (FIG. 1, Effect of arabinoxylan from oat husks
(9.38% relative to pulp) on the tear-tensile plot of beech sulfite
pulp). It is obvious that the samples show clearly better values in
both strengths by the addition of the arabinoxylan such that the
whole curve is displaced to a higher level.
[0056] The specific volume of the pulp is characterised by the
bulk, which is plotted in FIG. 2 against the tensile breaking
strength (Effect of arabinoxylan from oat husks (9.38% relative to
pulp) on the bulk-tensile plot of beech sulfite pulp). It is clear
that the curve for the different points of the degree of refinement
is displaced to higher bulk values. In order to produce a product
with the desired strength a higher sheet volume can be produced by
the addition of the arabinoxylan. The increased bulk leads to an
increase in the light scattering coefficients and thus to improved
optical properties.
[0057] Although the invention has been described in detail in the
foregoing for the purpose of illustration, it is to be understood
that such detail is solely for that purpose and that variations can
be made therein by those skilled in the art without departing from
the spirit and scope of the invention except as it may be limited
by the claims.
* * * * *