Note: Descriptions are shown in the official language in which they were submitted.
CA 02334532 2000-12-05
WO 99/64677 PCT/NL99/00351
Title: A process for making paper
The invention relates to a process for making paper
and to the use of starch in said process.
In order to increase the strength properties of
paper, it has been common practice during the last thirty
years to add cationic starch at the wet-end stage of the
papermaking process. The wet-end of the papermaking process
refers to the stages of the papermaking process, wherein a
pulp of fibers, obtained from cellulose-based materials, such
as recycled, used paper, wood, cotton, or alternative
sources, is being processed. The term "wet-end" originates in
the large amounts of water, in the presence of which the pulp
is processed.
During the last decade, there have been several
trends in the papermaking process which either call for more
starch in the pape:r than is feasible with cationic starch, or
which make the application of cationic starch more difficult.
One of these trends is the environmental demand to recycle
paper. As paper is recycled, the fibers of the paper tend to
become shorter and weaker, the latter of which is due to
reduced interactions among the fibers. As a result, increased
amounts of starch are necessary in the wet-end of the
papermaking in order to produce a paper which is sufficiently
strong. It has been found that after paper has been recycled
a certain number of times, the loss of strength due to
recycling cannot be compensated by adding cationic starch,
leading to paper having an inferior paper strength.
Another trend is the urge to produce cheaper paper.
This can be achieved by incorporating large amounts of a
cheap filler into the paper. However, a larger filler content
of the paper results in a deterioration of paper strength,
which gives rise to a demand for the addition of increased
amounts of starch in the wet-end.
Yet another trend concerns a change in the
apparatuses used in the papermaking process. The
conventionally used size-press is more and more being
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2
replaced by a premetering size-press. The use of a
premetering size-press often has the effect that starch
penetrates to lesser degree into the paper sheet than when a
conventional size-press is used. As a result, the starch
provides a smaller contribution to the strength of the paper.
Moreover, the use of a premetering size-press for
pigmentizing diminishes the internal strength of the paper
even more. Therefore, it is desired to provide an increase of
the strength of the paper obtained in the wet-end.
1.0 In "Anionic starch: an effective wet-end concept for
enhancing paper strength", Proceedings of the PITA Annual
Conference, 87-91, Manchester, October 1997, J. Terpstra and
R.P. Versluijs have proposed to use anionic starch instead of
cationic starch as a strengthening agent in the wet-end of
the papermaking process, in order to achieve a greater
internal strength of the paper produced. This concept of
using anionic starch has also been described in P. Brouwer,
Wochenblatt fur Papierfabrikation, 19 (1997), 928-937,
WO-A-93/01353 and TniO-A-96/05373, and may be explained as
follows.
2 0
The fibers and filler particles, which are used to
produce paper from, are negatively charged. When cationic
starch is used as a paper strengthening agent, its retention
is mainly caused by the interaction between the positively
charged starch and the negatively charged fibers and filler
particles. In order to adhere anionic starch molecules onto
anionic fibers and filler particles, use is made of a so-
called cationic fi:cative. In principle, any cationic paper
aid can be used as a fixative for the anionic starch,
:30 although some lead to better results than others. Because
they are cheap and hardly affected by water hardness,
polyaluminum chlorides are considered very attractive
fixatives. Other materials that have been proposed for use as
a fixative in this regard are, inter alia, alum, or cationic
polymers, such as polydimethyldiallylammonium chloride and
polyamines.
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It has been found that, by using anionic starch in
combination with a suitable fixative, it is possible to
incorporate up to five times as much starch into a paper
sheet in comparison with the case wherein only cationic
starch is used as a strengthening agent. Of course, this
results in a much stronger paper sheet. At the same time, the
retention of the starch in a papermaking process is much
higher when anionic starch and a fixative are used instead of
cationic starch. This means, that a much smaller part of the
starch, which is added to the pulp in the wet-end of the
papermaking process, is lost to the processing water.
Furthermore, by using anionic starch in combination with a
suitable fixative, it has been found that the retention of
fines and fillers is increased substantially, and it is
possible to reduce the refining. Also, an increase in
dewatering speed has been observed.
A disadvantage of the use of anionic starch instead
of cationic starch in the wet-end of the papermaking process
resides in the necessity of using a fixative. Even though
some of the fixatives proposed in the art are relatively
cheap, the costs of the paper that is produced may increase
considerably because of the use of the fixative. Also, as the
fixative is a cationic compound, it is inevitable that
anionic counterions are added to the paper along with the
fixative. Often, the counterions are chloride ions which are
corrosive. Furtherniore, the use of a fixative may lead to a
hardening of the ps-ocess water and to the production of
salts, which may iriterfere with other papermaking aids.
Surprisingly, it has now been found that the above
described disadvantages of the use of anionic starch as a
strengthening agent in paper may be mitigated by using an
anionic starch which primarily comprises amylopectin.
Hence, the invention relates to a process for making
paper wherein an anionic starch, which is based on a starch
:35 comprising at least.95 wt.%, based on dry substance of the
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4
starch, of amylopectin, or a derivative of said starch, is
used in combination with a fixative as a strengthening agent.
The use of the specific anionic starch has been found
to make it possible to use significantly smaller amounts of a
fixative, when compared with the use of a conventional
anionic starch. Moreover, the incorporation of an anionic
starch which primarily comprises amylopectin into a paper
sheet leads to a paper sheet having a superior strength.
Most starch types consist of granules in which two
1.0 types of glucose polymers are present. These are amylose (15-
35 wt.% on dry substance) and amylopectin (65-85 wt.% on dry
substance). Amylose consists of unbranched or slightly
branched molecules having an average degree of polymerization
of 1000 to 5000, depending on the starch type. Amylopectin
consists of very large, highly branched molecules having an
average degree of polymerization of 1,000,000 or more. The
commercially most important starch types (maize starch,
potato starch, wheat starch and tapioca starch) contain 15 to
30 wt.% amylose.
Of some cereal types, such as barley, maize, millet,
wheat, milo, rice and sorghum, there are varieties of which
the starch granules nearly completely consist of amylopectin.
Calculated as weight percent on dry substance, these starch
granules contain more than 95%, and usually more than 98%
:25 amylopectin. The arnylose content of these cereal starch
granules is thus less than 5%, and usually less than 2%. The
above cereal varieties are also referred to as waxy cereal
grains, and the amylopectin-starch granules isolated
therefrom as waxy cereal starches.
In contrast to the situation of different cereals,
root and tuber varieties of which the starch granules nearly
exclusively consis=t of amylopectin are not known in nature.
For instance, potato starch granules isolated from potato
tubers usually contain about 20% amylose and 80% amylopectin
(wt.% on dry substance). During the past 10 years, however,
successful efforts have been made to cultivate by genetic
CA 02334532 2007-02-21
modification potato plants which, in the potato tubers, form
starch granules consisting for more than 95 wtA (on dry
substance) of amylopectin. It has even been found feasible to
produce potato tubers comprising substantially only
5 amylopectin.
In the formation of starch granules, different
enzymes are catalytically active. Of these enzymes, the
granule-bound starch synthase (GBSS) is involved in the
formation of amylose. The presence of the GBSS enzyme depends
on the activity of genes encoding for said GBSS enzyme.
Elimination or inhibition of the expression of these specific
genes results in the production of the GBSS enzyme being
prevented or limited. The elimination of these genes can be
realized by genetic modification of potato plant material or
by recessive mutation. An example thereof is the amylose-free
mutant of the potato (amf) of which the starch substantially
only contains amylopectin through a recessive mutation in the
GBSS gene. This mutation technique is described in, inter
alia, J.H.M. Hovenkamp-Hermelink et al., "Isolation of
amylose-free starch mutant of the potato (Solanum tuberosurn
L.)", Theor. Appl. Gent., (1987), 75:217-221, and E. Jacobsen
et al., "Introduction of an amylose-free (amf) mutant into
breeding of cultivated potato, Solanum tuberosurn L.,
Euphytica, (1991), 53:247-253.
Elimination or inhibition of the expression of the
GBSS gene in the potato is also possible by using so-called
antisense inhibition. This genetic modification of the potato
is described in R.G.F. Visser et al., "Inhibition of the
expression of the gene for granule-bound starch synthase in
potato by antisense constructs", Mol. Gen. Genet., (1991),
225:289-296.
By using genetic modification, it has been
found possible to cultivate and breed roots and
tubers, for instance potato, yam, or cassave (South
African Patent Application No. ZA1997000004383,
publication date: December 23, 1997), of which the
starch granules contain little or no amylose. As
referred to herein, amylopectin-potato starch is
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the potato starch granules isolated from potato tubers and
having an amylopectin content of at least 95 wt.% based on
dry substance.
Regarding production possibilities and properties,
there are significant differences between amylopectin-potato
starch on the one riand, and the waxy cereal starches on the
other hand. This particularly applies to waxy maize starch,
which is commercially by far the most important waxy cereal'
starch. The cultivation of waxy maize, suitable for the
_LO production of waxy maize starch is not commercially feasible
in countries havincl a cold or temperate climate, such as The
Netherlands, Belgium, England, Germany, Poland, Sweden and
Denmark. The climate in these countries, however, is suitable
for the cultivatioii of potatoes. Tapioca starch, obtained
:15 from cassave, may be produced in countries having a warm
climate, such as is found in regions of South East Asia and
South America.
The compos_Ltion and properties of root and tuber
starch, such as amylopectin-potato starch and amylopectin-
20 tapioca starch, differ from those of the waxy cereal
starches. Amylopectin-potato starch has a much lower content
of lipids and proteins than the waxy cereal starches.
Problems regarding odor and foaming, which, because of the
lipids and/or proteins, may occur when using waxy cereal
25 starch products (native and modified), do not occur, or occur
to a much lesser degree when using corresponding amylopectin-
potato starch products. In contrast to the waxy cereal
starches, amylopectin-potato starch contains chemically bound
phosphate groups. As a result, amylopectin-potato starch
30 products in a dissolved state have a distinct polyelectrolyte
character.
The invention contemplates the use of anionic starch
obtained from cereal and fruit sources on the one hand, and
root and tuber sources on the other hand. Of the cereal
35 starches, waxy maize starch has proven very suitable. In
general, however, root and tuber starches are more preferred.
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As has been indicated above, it is often advantageous to use
a starch having a very low content of lipids and/or proteins.
The use of anionic amylopectin-potato starch and amylopectin-
tapioca starch as a strengthening agent in paper has been
found to lead to a particularly strong paper sheet.
By the term anionic, starch is meant a starch having a
charge density of at least 0.03 eq/mg starch, preferably at
least 0.15 eq/mg starch. In the context of the invention,
the charge density is defined as the amount of a cationic
polymer (methyl glycol chitosan iodide, Sigma M-3150) which
has to be added to a known amount of dissolved starch in
order to reach the equivalence point. This equivalence point
may be determined by measuring the electrophoretic
zetapotential of the dispersion to which silicate particles
1.5 are added as indicator. The zetapotential can for instance be
measured by using a Malvern Zetasizer 3.
The anionic starch, which, according to the
invention, is used in combination with a fixative as a
strengthening agent in paper, may be prepared from the starch
comprising at least 95 wt.%, based on dry substance of the
starch, of amylopectin, or the derivative of said starch, on
which it is based in any manner known for regular starch
comprising both amylopectin and amylose. For a description of
a possible manner of preparing an anionic starch, reference
may be made to O.B. Wurzburg (Ed.), "Modified Starches:
Properties and Uses", CRC Press Inc., Boca Eaton, Florida,
1986.
Examples of anionic starch may be obtained by
introduction of any anionic substituents or by any oxidation
:30 process known in the derivatization of starch. Suitable
examples of anionic: substituents are phosphate, phosphonate,
sulfonate, sulfate, (alkyl)succinate, anionic graft
copolymers and combinations thereof. An example of a suitable
oxidation is oxidation by hypochlorite. Preferably, a
:35 carboxymethyl of pho-sphated starch is used. The degree of
substitution (DS), which is the molar ratio between the
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8
amount of substituted hydroxyl groups of a glucose unit in
the starch and the amount of glucose units in the starch, may
range between 0.005 and 0.5, preferably between 0.01 and 0.2,
more preferably between 0.01 and 0.1.
Suitable derivatives of a starch comprising at least
95 wt.% amylopectin (based on dry substance) are starches
wherein, besides an anionic substituent, also one or more
non-ionic or cationic substituents may be introduced.
Suitable examples of non-ionic or cationic substituents may
be introduced by etherifcation idem esterifcation reactions,
such as methylation, ethylation, hydroxyethylation,
hydroxypropylation, alkylglycidylation (wherein the length of
the alkyl chain varies from 1 to 20 carbon atoms),
acetylation, propylation, carba-imidation, diethylamino-
ethylation, and/or trimethylammoniumhydroxypropylation.
Further, the starch may be crosslinked by any crosslinking
known in the derivatization of starch. Examples of suitable
crosslinking agentS include epichlorohydrine,
dichloropropanol, sodium trimethaphosphate,
phosphorousoxychloride and adipic acid anhydride. Of course,
care should be taken that the overall charge of the starch is
anionic.
As has beer.i indicated hereinabove, it is essential to
use a fixative, when anionic starch is used in the wet-end to
provide strength iri paper. In accordance with the invention,
suitable fixatives are cationically charged compounds, which
are capable of binciing anionic starch to anionic paper fibers
and filler particles. In principle, any cationic compound
that has been proposed for use as a fixative for anionic
:30 starch in the wet-end of a papermaking process can be used.
Examples include a:Lum, cationic starch or derivatives
thereof, polyaluminum compounds, and cationic polymers, such
as polydimethyldia:Llylarnmonium chlorides, polyamines,
polyvinylamines, polyethylene imines, dicyandiamide
polycondensates, or.other high molecular weight cationic
polymers or copolymers, e.g. comprising a quaternized
CA 02334532 2007-02-21
9
nitrogen atom or polyvinyl alcohol, and combinations thereof.
Such cationic polymers preferably should have a weight
average molecular weight of at least about 10,000, preferably
at least about 50,000, more preferably at least 100,000. In a
preferred embodiment, the cationic polymers have a weight
average molecular weight in the range from about 50,000 to
about 2,000,000.
Preferably, a fixative having a high charge density
is used. In this regard, a charge density higher than 1
eq/mg. is considered a high charge density. The charge
density of the fixative is defined as the amount of an
anionic polymer (sodium polystyrenesulfonate, Aldrich Product
# 243051)which has to be added to a known amount of
fixative (typically a few milliliters of the fixative in 500
ml demineralized water) in order to reach the equivalence
point. This equivalence point may be determined by measuring
the electrophoretic zetapotential of the dispersion to which
silicate particles are added as indicator. The zetapotential
can for instance be measured by using a Malvern Zetasizer 3.
It has been found that the use of a fixative having a higher
charge density leads to a decreased sensitivity of the
papermaking process for the hardness and conductivity of the
process water. Preferred fixatives having a high charge
density are polyaluminum compounds, such as polyaluminum
chloride or polyaluminum sulfate, polydimethyldiallylammonium
chlorides, polyamines, and combinations thereof.
In a process for making paper, the anionic starch,
which is based on a starch comprising at least 95 wt.%, based
on dry substance of the starch, of amylopectin, or a
derivative of said starch, and the fixative are added at the
wet-end of the process. This means that they are added to a
pulp comprising fibers obtained from recycled paper or from
wood and water. It is common practice to add a filler
compound to the pulp. In accordance with the invention, any
of the commonly used filler compounds, such as clay, ground
CaCO3, precipitated CaCOõ talc or titaniumdioxide, may be
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employed. Preferably, the filler compound is added to the
pulp prior to the addition of the anionic starch and the
fixative. Further, the anionic starch is preferably added to
the pulp before the fixative is added.
5 The amount in which the anionic starch is added to
the pulp will depend on the desired paper strength.
Generally, the amount will vary between 0.1 and 10 wt.%,
preferably between 1 and 5 wt.%, based on (consistency) the-
weight of the solidts in the pulp (fibers, filler compounds,
T1 0 fines, and so forth).
The amount of the fixative which is added depends on
the nature of the fixative and the pulp that is being used
and on the amount of anionic starch that is to be
incorporated into t:he paper. Generally, the amount of
fixative is chosen such that at least 60%, preferably at
least 80%, more preferably at least 90% adsorption of the
anionic starch is attained. It is noted that in this regard a
distinction should be made between adsorption and retention.
Retention refers to the amount of starch added in the wet-end
:20 that is eventually incorporated in the paper, while
adsorption refers to the amount of starch added in the wet-
end that adsorbs to the paper fibers in the pulp in the wet-
end. The skilled person will be able to adjust the amount of
the fixative to the circumstances at hand. Typical values
differ for inorganic and organic fixatives. When normal,
amylose containing anionic starch is used, the weight ratio
of fixative to anionic starch is about 1:1 for inorganic
fixatives and about 1:4 for organic fixatives. When, in
accordance with the invention, an amylopectin type anionic
starch is used, these amounts may be reduced by a factor of
about 8-10 for organic fixatives and a factor of about 4-6
for inorganic fixatives.
The pulp that is used for making paper in a process
according to the invention may be any aqueous suspension of
cellulose-based fibers that can be used to make paper from.
After the anionic starch and the fixative have been added to
-- -------- - -- -------
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~ 11
the pulp, the pulp may be processed into paper in any known
manner.
The invention will now be further elucidated by the
following, non-restrictive examples.
EXAMPLE I
A solution of 30 g urea and 31,1 g phosphoric acid
(85%) in 85 ml of water was neutralized to pH 6.0 with 50%
NaOH. This solution was mixed with 600 g of amyopectin-potato
starch (moisture 20%) for 30 minutes in a Hobart mixer. The
mixture was equilibrated and subsequently dried in a Retsch
fluid bed dryer for 30 minutes at 60 C, and for 30 minutes at
90 C. the mixture was heated at 145 C in a fluid bed reactor
for 30 minutes. The resulting product was HK4017A and had a
charge density of C.47 eq/mg.
EXAMPLE II
A solution of 30 g urea and 31,1 g phosphoric acid
(85%) in 85 ml of water was neutralized to pH 6.0 with 50%
NaOH. This solutiori was mixed with 600 g of amyopectin-potato
starch (moisture 20%) for 30 minutes in a Hobart mixer. The
mixture was equilibrated and subsequently dried in a Retsch
fluid bed dryer for 30 minutes at 60 C, and for 30 minutes at
90 C. the mixture was heated at 140 C in a fluid bed reactor
for 30 minutes. The resulting product was HK4041B and had a
charge density of 0.34 eq/mg.
:30
EXAMPLE III
The adsorpt:ion of the starch on to solid pulp
components was studied as follows. To a pulp (consistency of
1%) anionic starch was added (dosage 3% on consistency). The
pulp was stirred in a baffled beaker at 800 rpm. After 60
seconds a fixative was added and after another 60 seconds the
CA 02334532 2007-02-21
12
pulp was filtered. The starch adsorption was determined by
measuring the amount of non-adsorbed starch in the filtrate.
The pulp was a birch sulfate pulp beaten to 35 SR
(measured at 21 C) at a consistency of 2% in tap-water using
a Hollander. After beating the pulp was diluted to a
consistency of 1% with tap-water.
The pulp was divided in three separate batches. The
conductivity of one batch was set to 3.01 mS/cm with sodium-
sulphate (Na2SO4 = 10H2O1 Merck reinst) . The water hardness of
the second batch was increased from ca. 11 to ca. 80 GH by
adding calcium chloride (CaCl2 =2HZO, Merck reinst). The
resulting conductivity of this batch was 3.01 mS/cm. To the
third batch no salt was added. The conductivity and water
hardness was 0.51 mS/cm and ca. 11 GH, respectively. The
conductivity of the pulp was measured with a Radiometer CDM
80 conductivity meter.
The starches used are: anionic potato starch PR9510 A
(commercialized as Aniofax AP25) and two anionic amylopectin
potato starches: HK4017A and HK4041B. The latter two products
were prepared as described in Examples I and II,
respectively. The starches were cooked with life steam
starting with a 10% slurry in tap-water. After cooking the
starch solutions were diluted to 5% with hot tap-water. The
viscosities of the 5% solutions were determined using a
Brookfield LVTDV-II at 60 rpm (see table 1). The degrees of
substitution of phosphate in the starches were determined as
described in J.Th.L.B. Rameau and J. ten Have, Chemisch
Weekblad, No. 50 (1951), after excess of phosphate was
removed by dialysis against 0.05 N HC1 solution for 48 hours
and against demineralized water for 24 hours, and
neutralization to pH 7-8 with 0.10 N NaOH.
CA 02334532 2007-02-21
13
TaYile 1: Characterization of the applied starches
arc a.scosi y p
(50 C, 5%)
[mol/mol] [mPa-s]
PR9510A (AZM) 0.022 391 7.1
HK4017A (AAZM) 0.024 680 7.1
HK4041B (AAZM) 0.018 252 7.2
TM
The used fixatives are Sachtoklar (obtained from
TM
Sachtleben Chemie GmbH, Germany), Retinal 1030 (obtained from
Joud, france), and PD5-8159 (obtained from Allied Colloids
Ltd. , UK).
TM TM
Before use, the fixatives Sachtoklar and Retinal 1030
were diluted by a factor of 10 with demineralized water. A
solution of PD5-8159 was prepared by first dissolving 1 g of
polymer in 4 g of acetone. After stirring for 30 minutes 95 g
demineralized water was added. Some properties of the
fixatives are listed in table 2.
The charge density of the fixatives was determined by
adding sodium polystyrenesulfonate to a known amount of
fixative (typically a few milliliters of the fixative in 500
ml demineralized water). The amount necessary in order to
reach the equivalence point was the charge density. This
equivalence point was determined by measuring the
electrophoretic zetapotential, using a Malvern Zetasizer 3,
of the dispersion to which silicate particles were added as
indicator.
Table 2: Characterization of the applied fixatives
ixa ive pH of iscosi y ol e 7CIFar-ge ensi y
fixative (20 C,
as received as received,
60 rpm) [%] [ eq/mg]
[mPa=s)
SachtoklarTM2.3 7.3 23.2 +2.0
(= Paper-
PAC-N)
RetinalTM 5.7 950 50.1 +7.6
1030
PD5-8159 6.6 2240 26.8 +7.0
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WO 99/64677 PCT/NL99/00351
14
The amount of starch in the filtrate was determined
in an enzymatic method. In accordance with this method,
starch is first converted into glucose with an a-amylase and
an amyloglucosidase. Subsequently, the amount of glucose is
determined spectroscopically using a hexokinase test method
(Boehringer no. 716251). The amount of starch is calculated
from the obtained amount of glucose using a correction factor
for incomplete conversion of the starch into glucose by the
enzymes. The applied enzymatic conversion factor of Aniofax
AP25 is 0.78. The starch adsorption was calculated from the
enzymatically determined starch concentration in the filtrate
using the following expression:
A=1-CSGV eq. A
where A is the starch adsorption, cs is the starch
concentration in the filtrate, V is the total volume of water
and G is the added amount of starch. The total amount of
water is obtained by:
V=Vp - dsp+Vt - ds, +VrX-dsfX
eq. B
where Vp, Vst and Vfl, represent the volume of the batch
~.:
of pulp, the volume of the starch dosage and the volume of
the fixative dosage, respectively. The total volume is
corrected for the dry solids contents dsp, dsst and dsfi,r
(assuming density of dry solids is 1 g/ml).
The starch adsorption was investigated by varying
three parameters: starch, fixative and pulp properties
(conductivity and water hardness). The results will be
discussed using the fixative dosage expressed as dry on
fiber.
CA 02334532 2007-02-21
An overview of the fixative dosages needed for a
starch adsorption of at least 90% is given in table 3 for
each starch and each experimental condition.
The smallest amount of fixative for a starch
5 adsorption >90% is needed in case of HK4017A. For PD5-8159
the fixative dosage is 1.5 to 2.5 times larger in case of
TM
HK4041B and 2.5 to 5 times for PR9510A. For Retinal 1030 the
increase of the dosage is a factor 2 to 2.5 for HK4041B and-2
to at least 5 for PR9510A.
TM
10 Also for the PAC Sachtoklar the best results are
obtained for the amylopectin starches. In case of PR9510A the
PAC dosage is 1.5 to more than 3.5 times higher than in case
of HK4017A.
A noteworthy difference between PR9510A and HK4017A
15 is the effectivity of the organic fixatives PD5-8159 and
TM
Retinal 1030 at high water hardness. With HK4017A the starch
adsorpLion is higher at high hardness for both fixatives,
while with PR9510A the adsorption is the same or lower. Thus,
with this anionic AAZM a high water hardness leads to higher
starch adsorptions, not only for PACs but also for the tested
organic fixatives. In case of the other anionic AAZM,
HK4041B, the same effect of water hardness is observed for
TM
Retinal 1030, but not for PDS-8159.
These results confirm that the applied organic
fixatives are more effective in adsorbing amylopectin
molecules than in adsorbing amylose molecules.
CA 02334532 2007-02-21
16
Table 3: Data for comparison of the starches. The listed
fixative dosage is the lowest dosage for which a starch
adsorption higher than 90o is obtained. The ratio of fixative
dosages is the amount of fixa ti ve needed with HK4 041B or
PR9510A divided by the amount needed for HK4017A.
ixa ive on . ar - arc ix. arc a
P-
nr. (mS/cm) ness dos. ads. fix. dos.
ac o ar TM . 0.46
ac o arTM .
ac o ar TM 0. - . . .
-
ac o ar TM . 93.4
ac o ar'TM ' s . .
saclit o ar- TM * . > .
ac o ar TM . . -
ac o ar TM 2.98 96.9
9 ac o ar TM .
PD5-8159 . * 92.3 .
FL)b-8159 . .
- . .
19 e lna TM
1030
e i.na TM 97.2
1030
21 e i na TM . 0.25 .C-S
1030
e ina TM . -
1030
e ina ,M .
1030
e i.na Tm * >4
25 1030 2.00 95.7 8
2.6 e 1.na TM . -
1030
27- e ina TM . .
1030
e ina jM 98 __B7R9510A U.25 I q'i . -i
*
1030
*not according to invention
