U.S. patent application number 09/923623 was filed with the patent office on 2002-07-25 for sizing dispersion.
Invention is credited to Morgan, Nicholas Stuart, Nicholass, John Franklin.
Application Number | 20020096294 09/923623 |
Document ID | / |
Family ID | 26074203 |
Filed Date | 2002-07-25 |
United States Patent
Application |
20020096294 |
Kind Code |
A1 |
Nicholass, John Franklin ;
et al. |
July 25, 2002 |
Sizing dispersion
Abstract
The present invention refers to an aqueous sizing dispersion
comprising a ketene dimer based sizing agent, wherein the sizing
agent is obtained by (i) providing a mixture of fatty acid halides
comprising saturated fatty acid halides having 12 and 16 carbon
atoms, the amount of fatty acid halides having 16 carbon atoms
being from 20 up to 500 molar % based on total amount of fatty
acids having 12 carbon atoms, and (ii) removal of hydrogen halide
from the saturated fatty acid halides thereby forming ketene dimer.
Furthermore, the invention also includes a process for the
production of paper comprising adding the aqueous dispersion to a
cellulosic suspension, forming and dewatering the suspension on a
wire.
Inventors: |
Nicholass, John Franklin;
(Bristol, GB) ; Morgan, Nicholas Stuart; (Weston
Super Mare, GB) |
Correspondence
Address: |
Richard P. Fennelly
Akzo Nobel Inc.
7 Livingsteone Avenue
Dobbs Ferry
NY
10522-3408
US
|
Family ID: |
26074203 |
Appl. No.: |
09/923623 |
Filed: |
August 7, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60223370 |
Aug 7, 2000 |
|
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Current U.S.
Class: |
162/179 ;
162/175 |
Current CPC
Class: |
D21H 21/16 20130101;
D21H 17/17 20130101 |
Class at
Publication: |
162/179 ;
162/175 |
International
Class: |
D21H 021/16; D21H
017/14; D21H 017/24 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 7, 2000 |
EP |
00850134.8 |
Claims
1. An aqueous sizing dispersion comprising a ketene dimer based
sizing agent, wherein the sizing agent is obtained by (i) providing
a mixture of fatty acid halides comprising saturated fatty acid
halides having 12 and 16 carbon atoms, the amount of fatty acid
halides having 16 carbon atoms being from 20 up to 500 molar %
based on total amount of fatty acids having 12 carbon atoms, and
(ii) removal of hydrogen halide from the saturated fatty acid
halides thereby forming ketene dimer.
2. The dispersion according to claim 1, wherein the amount of fatty
acid halides having 16 carbon atoms is from 30 up to 300 molar %
based on the total amount of fatty acid halides having 12 carbon
atoms.
3. The dispersion according to claim 1, wherein said dispersion
comprises a cationic polysaccharide in an amount from about 0.1 up
to 50% by weight based on sizing agent.
4. The dispersion according to claim 3, wherein the cationic
polysaccharide is cationic starch having a cationic substitution
(DS.sub.c) from about 0.01 up to about 0.2.
5. The dispersion according to claim 1, wherein said dispersion
comprises a cationic polysaccharide in an amount from about 0.1 up
to 50% by weight based on sizing agent and a naphthalene sulphonate
condensation polymer in an amount from about 0.1 up to 50% by
weight based on sizing agent.
6. An aqueous sizing dispersion comprising an amount of from about
5 up to about 50% by weight of a ketene dimer based sizing agent,
wherein the sizing agent is obtained by (i) providing a mixture of
fatty acid halides comprising saturated fatty acid halides having
12, 14 and 16 carbon atoms, the amount of fatty acid halides having
16 carbon atoms being from 30 up to 300 molar % based on total
amount of fatty acid halides having 12 carbon atoms, the amount of
saturated fatty acid halides having 14 carbon atoms being from
about 45 up to about 400 molar %, and (ii) removal of hydrogen
halide from the saturated fatty acid halides thereby forming ketene
dimer.
7. The dispersion according to claim 6, wherein said dispersion
comprises a cationic polysaccharide in an amount from about 0.1 up
to 50% by weight based on sizing agent.
8. The dispersion according to claim 7, wherein the cationic
polysaccharide is cationic starch having a cationic substitution
(DS.sub.c) from about 0.01 up to about 0.2.
9. The dispersion according to claim 6, wherein said dispersion
comprises a cationic polysaccharide in an amount from about 0.1 up
to 50% by weight based on sizing agent and a naphthalene sulphonate
condensation polymer in an amount from about 0.1 up to 50% by
weight based on sizing agent.
10. An aqueous sizing dispersion comprising an amount of from about
5 up to about 50% by weight of a ketene dimer based sizing agent,
wherein the sizing agent is obtained by (i) providing a mixture of
fatty acid halides comprising saturated fatty acid halides having
12, 14 and 16 carbon atoms, the amount of fatty acid halides having
16 carbon atoms being from 30 up to 300 molar % based on amount of
fatty acid halides having 12 carbon atoms, the amount of saturated
fatty acid halides having 14 carbon atoms being from about 45 up to
about 400 molar % based on amount of fatty acid halides having 12
carbon atoms, the amount of fatty acid halides having 12 carbon
atoms being up to about 45% by weight based on total fatty acid
halides in the mixture, and (ii) removal of hydrogen halide from
the saturated fatty acid halides thereby forming ketene dimer.
11. The dispersion according to claim 10, wherein said dispersion
comprises a cationic polysaccharide in an amount from about 0.1 up
to 50% by weight based on sizing agent.
12. The dispersion according to claim 11, wherein the cationic
polysaccharide is cationic starch having a cationic substitution
(DS.sub.c) from about 0.01 up to about 0.2.
13. The dispersion according to claim 10, wherein said dispersion
comprises a cationic polysaccharide in an amount from about 0.1 up
to 50% by weight based on sizing agent and a naphthalene sulphonate
condensation polymer in an amount from about 0.1 up to 50% by
weight based on sizing agent.
14. An aqueous sizing dispersion comprising an amount of from about
5 up to about 50% by weight of a ketene dimer based sizing agent,
wherein the sizing agent is obtained by (i) providing a mixture of
fatty acid halides comprising saturated fatty acid halides having
12, 14 and 16 carbon atoms, the amount of fatty acid halides having
16 carbon atoms being from 30 up to 300 molar % based on amount of
fatty acid halides having 12 carbon atoms, the amount of saturated
fatty acid halides having 14 carbon atoms being from about 45 up to
about 400 molar % based on amount of fatty acid halides having 12
carbon atoms, the amount of fatty acid halides having 12 carbon
atoms being up to about 45% by weight based on total fatty acid
halides in the mixture, the reaction mixture being essentially free
from unsaturated fatty acid halides and branched fatty acid
halides, and (ii) removal of hydrogen halide from the saturated
fatty acid halides thereby forming ketene dimer.
15. The dispersion according to claim 14, wherein said dispersion
comprises a cationic polysaccharide in an amount from about 0.1 up
to 50% by weight based on sizing agent.
16. The dispersion according to claim 15, wherein the cationic
polysaccharide is cationic starch having a cationic substitution
(DS.sub.c) from about 0.01 up to about 0.2.
17. The dispersion according to claim 14, wherein said dispersion
comprises a cationic polysaccharide in an amount from about 0.1 up
to 50% by weight based on sizing agent and a naphthalene sulphonate
condensation polymer in an amount from about 0.1 up to 50% by
weight based on sizing agent.
18. A process for the production of paper comprising adding an
aqueous sizing dispersion comprising a ketene dimer based sizing
agent, wherein the sizing agent is obtained by (i) providing a
mixture of fatty acid halides comprising saturated fatty acid
halides having 12 and 16 carbon atoms, the amount of fatty acid
halides having 16 carbon atoms being from 20 up to 500 molar %
based on total amount of fatty acids having 12 carbon atoms, and
(ii) removal of hydrogen halide from the saturated fatty acid
halides thereby forming ketene dimer, to a cellulosic suspension,
forming and dewatering the suspension on a wire.
Description
[0001] The present invention relates to an aqueous sizing
dispersion comprising a ketene dimer based sizing agent and a
process for production of paper comprising adding the aqueous
sizing dispersion.
[0002] Cellulose-reactive sizing agents, such as those based on
ketene dimers, also referred to as 2-oxetanone sizing agents, are
widely used in papermaking at neutral or slightly alkaline stock
pH's in order to give paper and paper board some degree of
resistance to wetting and penetration by aqueous liquids. Paper
sizes based on cellulose-reactive sizing agents are generally
provided in the form of dispersions containing an aqueous phase and
finely divided particles or droplets of the sizing agent dispersed
therein. The dispersions are usually prepared by homogenising the
hydrophobic, water insoluble material in an aqueous phase in the
presence of a dispersant using shear forces and fairly high
temperatures. The ketene dimers are made from different fatty acid
mixtures which results in sizing agents with varying melting
temperature ranges. Fatty acid mixtures containing fatty acids
having carbon chains with irregularities like double bonds and/or
chain branching usually have lower melting temperatures than
regular ketene dimer sizing agent produced from fatty acid mixtures
containing unsaturated straight chain fatty acids having mainly 16
and 18 carbon atoms. Ketene dimer sizing agents made from fatty
acid mixtures rendering lower melting points have show improved
properties compared to regular ketene dimer sizing agents. However,
paper sized with dispersions containing ketene dimer sizing agents
having lower melting ranges have impaired toner adhesion
properties.
[0003] EP 0666368 A2 refers to the use of paper in high speed
converting or reprographic operations where the paper is sized with
a 2-oxetanone sizing agent which is not a solid at 35.degree. C.
The sizing agent is made from a fatty acid selected from the group
consisting of oleic, linoleic, linolenic or palmitoleic fatty acid
chlorides or a mixture of them.
[0004] EP 0629741 A1 relates to paper sized with 2-oxetanone sizing
agents having one and two 2-oxetanone rings. Exemplified saturated
monocarboxylic acids are inter alia stearic, myristic, palmitic,
decanoic, etc. However, the document is silent about molar ratios
between specific saturated carboxylic acids.
[0005] EP 0742315 A1 discloses a sizing composition which is not a
solid at 35.degree. C. comprising a mixture of 2-oxetanone
compounds containing saturated and unsaturated fatty acids.
Saturated fatty acids which are mentioned are stearic, palmitic,
myristic and lauric, however, the document does not disclose
specific molar ratios between specific saturated carboxylic
acids.
[0006] WO 98141686 A1 refers to a method of manufacturing a paper
grade whereby the paper is sized with a 2-oxetanone based size
whereby at least one of the fatty acids used has a branched carbon
chain with no double bonds. The only exemplified fatty acids are
those containing 16 and 18 carbon atoms.
[0007] It is accordingly an objective of the present invention to
provide an aqueous dispersion comprising a ketene dimer sizing
agent which results in paper having improved toner adhesion
properties.
[0008] A further objective of the present invention is to provide
an aqueous dispersion which improves toner adhesion properties
while maintaining desirable non-impact printing (NIP) properties of
paper.
[0009] Yet a further objective of the present invention is to
provide an aqueous sizing dispersion comprising a sizing agent
having a lower melting temperature range than regular sizing agents
rendering paper with improved toner adhesion properties.
[0010] Another objective of the present invention is that the paper
obtained will improve performance in printers, e.g. Oc printers,
such as less ketone transfer to the belt. Still further objects of
the invention will appear hereinafter.
[0011] In accordance with the present invention it has surprisingly
been found that paper with improved toner adhesion properties is
obtained when an aqueous dispersion according to the claims is used
for stock sizing or surface sizing of paper. More specifically, the
invention relates to an aqueous sizing dispersion comprising a
ketene dimer based sizing agent, wherein the sizing agent is
obtained by
[0012] (i) providing a mixture of fatty acid halides comprising
saturated fatty acid halides having 12 and 16 carbon atoms, the
amount of fatty acid halides having 16 carbon atoms being from 20
up to 500 molar % based on total amount of fatty acids having 12
carbon atoms, and
[0013] (ii) removal of hydrogen halide from the saturated fatty
acid halides thereby forming ketene dimer. The invention further
relates to a process of producing paper comprising adding the
aqueous sizing dispersion to a cellulosic suspension, forming and
dewatering the suspension on a wire.
[0014] According to the present invention the ketene dimer based
sizing agent is made from a mixture of fatty acids, suitably
monocarboxylic fatty acids, comprising saturated fatty acids having
12 and 16 carbon atoms, whereby the amount of fatty acids having 16
carbon atoms is from 20 molar % up to 500 molar % based on total
amount of fatty acids having 12 carbon atoms. Suitably, the ketene
dimer based sizing agent is made from a mixture of fatty acids
comprising saturated fatty acids having 12 and 16 carbon atoms,
whereby the amount of fatty acids having 16 carbon atoms is from 25
molar % up to 400 molar % and most preferably the amount of fatty
acids having 16 carbon atoms is from 30 molar % up to 300 molar %
based on total amount of fatty acids having 12 carbon atoms. The
amount of fatty acids having 14 carbon atoms present in the mixture
may range from 20 molar % up to 500 molar % based on total fatty
acids having 12 carbon atoms, suitably, from 30 molar % up to 400
molar % and more preferably from 45 molar % up to 400 molar %. By
fatty acid is meant any carboxylic acid residue which can be used
for the production of ketene dimer based sizing agents such as
carboxylic (fatty) acid halides, suitably fatty acid chlorides. The
amount of fatty acids in the mixture having 12 carbon atoms can be
up to 45 weight % based on total fatty acids in the mixture,
suitably, up to 40 weight % and more preferably up to 35 weight %
based on total fatty acids in the mixture. Preferably, the fatty
acid mixture comprises fatty acids containing 12, 14, 16 and 18
carbon atoms in a more or less equimolar amount.
[0015] Suitably, the fatty acids contained in the mixture have from
6 up to 26 carbon atoms and more preferably from 10 up to 20 carbon
atoms which may contain irregularities such as chain branching
and/or double bonds. The fatty acids contained in the mixture can
be monocarboxylic acids and/or dicarboxylic acids. If dicarboxylic
acids are present, multimers are formed. Preferably, the mixture is
essentially free, or even more preferably, free from dicarboxylic
fatty acids, thus, the only ketene dimer sizing agents formed are
ketene dimers. Suitable saturated fatty acids present in the
mixture include caproic acid, caprylic acid, capric acid, lauric
acid, myristic acid, palmitic acid, stearic acid, arachidic acid,
behenic acid and lignoceric acid and mixtures thereof. Examples of
branched fatty acids are isostearic acid and isopalmitic acid.
[0016] According to one preferred embodiment of the present
invention the ketene dimer based sizing agent is made from a
mixture of fatty acids which is essentially free from branched
fatty acids, suitably, the mixture of fatty acids is free from
branched fatty acids. According to another preferred embodiment of
the present invention the fatty acid mixture is essentially free
from unsaturated and branched fatty acids. By essentially free is
meant that the amount of branched and/or unsaturated fatty acids in
the mixture is suitably less than 5 molar % based on fatty acid in
the mixture, more preferably less than 2 molar %.
[0017] The ketene dimer sizing agent can be prepared using methods
disclosed in EP 612739. The method suitably comprises providing
fatty acid chlorides formed from a reaction mixture of fatty acids
comprising saturated fatty acids having 12, e.g. lauric acid, and
16 carbon atoms, e.g. palmitic acid, whereby the amount of fatty
acids having 16 carbon atoms is from 20 molar % up to 500% based on
total amount of fatty acids having 12 carbon atoms by using
phosphorous trichloride or other conventional chlorinating agents.
The fatty acid chlorides are then dehydrochlorinated in the
presence of a tertiary amine which functions both as a reactant and
a solvent/diluent, whereby ketene dimers are formed. The ketene
dimers are obtained by stripping off the tertiary amine followed by
separation of formed crystals of tertiary amine hydrogen halide by
acid extraction.
[0018] Preferably, the ketene dimer sizing agent comprised in the
dispersion according to the invention is liquid in a temperature
range of from -30 up to 70.degree. C., suitably from 10 up to
50.degree. C., most preferably from 30 up to 45.degree. C. By
liquid is meant that the sizing agent per se flows without heat of
fusion.
[0019] The mixture of the ketene dimer based sizing agent may be
prepared by using methods for the preparation of ketene dimers or
multimers. In the first step suitably acid chlorides are formed
from a mixture of fatty acids using a chlorination agent. The fatty
acid chlorides are then dimerised in the presence of tertiary
amines such as triethyleamine to form ketene dimers or
multimers.
[0020] The aqueous dispersion comprising a ketene dimer based
sizing agent suitably contains agents which facilitate the
formation of emulsions or dispersions such as polyelectrolytes. The
polyelectrolytes present in the aqueous dispersion can be
non-ionic, anionic, cationic or amphoteric. The cationic or anionic
polyelectrolytes may contain groups of the opposite charge as long
as the overall charge is anionic or cationic, respectively. The
charged groups may be native or can be introduced synthetically.
The polyelectrolytes, often referred to as dispersing agents, can
be derived from natural or synthetic sources. Whereas suitable
natural sources are polysaccharides such as starch originating from
potato, corn, wheat, tapioca, rice, waxy maize or other starch
containing natural sources, suitable synthetic polyelectrolytes
include condensation polymers and vinyl addition polymers. Suitable
condensation polymers include epihalohydrin polymers, polyamidamine
polymers, polyamideamine-epichlorohydrin copolymers, polyamines,
dimethylamine-epichlorohydrin coploymers,
dimethylamine-ethylenediamine-e- pichlorohydrin copolymers,
polyethyleneimine polymers, polyurethanes, naphtalene sulphonates.
Suitable vinyl addition polymers include polyacrylamide and
polyethyleneoxid.
[0021] Anionic polyelectrolytes may have a degree of substitution
varying over a wide range; the degree of anionic substitution
(DS.sub.A) can be from 0.01 to 1.4, suitably from 0.1 to 1.2 and
preferably from 0.2 to 1.0. Cationic polyelectrolytes can have a
degree of substitution (DS.sub.C) from 0.01 to 1.0, suitably from
0.1 to 0.8 and preferably from 0.2 to 0.6.
[0022] By dispersion is meant any aqueous medium comprising finely
divided particles in solid and/or liquid state and/or particles in
any state therebetween.
[0023] According to one preferred embodiment the aqueous sizing
dispersion comprises a ketene dimer sizing agent and a cationic
starch. The cationic substitution (DS.sub.C) of the starch may vary
from 0.01 to 0.2, suitably from 0.1 to 0.15. Suitably, a further
anionic compound is present in the dispersion such as naphthalene
sulphonate condensation polymer in an amount from about 0.1 up to
about 50% by weight, suitably from 5 to 40% by weight, based on the
sizing agent.
[0024] According to yet another preferred embodiment the aqueous
dispersion comprising a ketene dimer sizing agent is essentially
free from starch which is liquid at a starch concentration of 30%
by weight at room temperature or slightly above, i.e. a viscosity
of less than 10000 cps.
[0025] Other suitable compounds can also be incorporated such as
fungicides, alum, aluminium containing compounds and polyaluminium
compounds.
[0026] The aqueous dispersion according to the invention can be
anionic or cationic depending on the amount of anionic and/or
cationic compounds such as polyelectrolytes/dispersing agents
present in the dispersions.
[0027] The aqueous dispersion according to the invention can be
produced by mixing an aqueous phase with the dispersing agent and
optionally any other compound or compounds facilitating the
formation of a dispersion and the ketene dimer based sizing agent,
preferably at a temperature where the sizing agent is liquid and
homogenising the composition so obtained suitably under
pressure.
[0028] The aqueous dispersion containing ketene dimer sizing agents
according to the invention can have ketene dimer contents within
the range of from 5 up to 50% by weight and preferably from 10 up
to 35% by weight, based on total dispersion.
[0029] The amount of dispersing agent/polyelectrolyte or any other
charged components present in the dispersion according to the
invention can be varied over a broad range depending on, among
other things, type and charge density of the dispersing agent, type
of sizing agent, desired anionicity/cationicity and solids content
of the resulting dispersion. In the dispersion, the dispersing
agent such a cationic polysaccharide, e.g. starch, can be present
in an amount of up to 100% by weight, usually from 0.1 to 50% by
weight, suitably from 5 to 40% by weight, based on the sizing
agent.
[0030] The aqueous dispersion comprising a ketene dimer based
sizing agent according to the invention can be used in a process
for the production of paper comprising adding an aqueous dispersion
of a ketene dimer sizing agent as described above to a stock
containing cellulosic fibres and optional fillers, dewatering the
stock on a wire to obtain paper. The aqueous dispersions may be
used both for surface sizing and internal or stock sizing.
Furthermore, the dispersions according to the invention are
suitably added to a cellulosic wet stock comprised in a process for
production of paper having runnability problems created by wet end
and press section deposits. The term "paper", as used herein, is
meant to include not only paper but all types of cellulose-based
products in sheet and web form, including, for example, board,
cardboard and paperboard. The stock contains cellulosic fibres,
optionally in combination with mineral fillers, and usually the
content of cellulosic fibres is at least 50% by weight, based on
dry stock. Examples of mineral fillers of conventional types
include kaolin, china clay, titanium dioxide, gypsum, talc and
natural and synthetic calcium carbonates such as chalk, ground
marble and precipitated calcium carbonate. The present invention
preferably relates to a method for the production of paper in which
an aqueous dispersion, as defined above, is used as a surface or
stock size. Suitably the amount of sizing agent either added to the
stock containing cellulosic fibres, and optional fillers, to be
drained on a wire to form paper, or applied on the paper surface as
a surface size, usually at the size press, is from 0.01 to 1.0% by
weight, based on the dry weight of cellulosic fibres and optional
fillers, preferably from 0.05 to 0.5% by weight, where the dosage
is mainly dependent on the quality of the pulp or paper to be
sized, the cellulose-reactive sizing agent used and the level of
sizing desired.
[0031] The dispersions according to the present invention are
preferably used in a process for the production of paper where the
stock comprises calcium carbonate such as chalk, preferably
precipitated calcium carbonate (PCC) or ground calcium carbonate
(GCC). Whereas chalk and other ground carbonates are produced by
the mechanical treatment, such as crushing and grinding, of
naturally occurring materials, precipitated calcium carbonate is a
different material produced synthetically in a chemical
precipitation process, usually the carbonation process, where
calcium hydroxide is converted to calcium carbonate by reaction
with carbon dioxide. The stock can contain calcium carbonate like
PCC in an amount up to about 35% by weight based on dry weight of
cellulosic fibres, suitably from 5 to 30% by weight and preferably
from 10 to 25% by weight.
[0032] Further additives which are conventional in papermaking may
also be comprised in the stock whereto the aqueous dispersion is
added such as dry drainage and retention agents, strength agents,
wet strength agents, optical brightening agents, dyes, etc.
[0033] The invention is further illustrated in more detail by the
following examples which, however, are only intended to illustrate
the invention and are not intended to limit the same.
EXAMPLE 1
[0034] An aqueous sizing dispersion according to the invention (no.
1) was prepared by mixing a ketene dimer based sizing agent which
was obtained from an equimolar mixture of saturated monocarboxylic
fatty acids containing 12, 14, 16 and 18 carbon atoms with cationic
starch having a cationic substitution (DSc) of 0.08 at a
temperature of 75.degree. C., passing the mixture through a
homogeniser in the presence of an aqueous solution containing
naphthalene sulphonate and then cooling the dispersion so formed.
The pH of the dispersion was adjusted to about 3-4 by the addition
of an aluminium compound. The amount of sizing agent in the
dispersion was 10% by weight based on total dispersion. The amount
of starch was 33% by weight based on sizing agent.
EXAMPLE 2
[0035] The general procedure of example 1 was repeated except that
the sizing agent used was prepared from a mixture of fatty acids
containing 65% by weight, based on fatty acid mixture, of
isostearic monocarboxylic acids and 35% by weight of a mixture of
saturated monocarboxylic acids with 16 and 18 carbon atoms, the
weight ratio of C16:C18 being 55:45. This dispersion was denoted
no.2 and was not according to the present invention.
EXAMPLE 3
[0036] The toner adhesion of paper sized with the sizing
dispersions of example 1 and 2 were evaluated in this example. The
paper sheets were prepared using a pilot plant machine. The
papermaking stock used contained 85 weight % of a 90:10 bleached
eucalyptus:spruce/pine sulphate pulp and 15 weight % precipitated
calcium carbonate (PCC) having a freeness of 35.degree. SR. The
size dispersions were used in conjunction with a commercial
retention and dewatering system containing cationic starch (HiCat
142; Roquette) and anionic modified aluminium-modified silica sol
(BMA 590, Eka Chemicals). which were added separately to the stock
in an amount of 1 weight % of cationic starch on dry fibre and 0.1
kg/tonne silica sol on dry fibre. The toner adhesion was measured
by using the crease test in accordance to ASTM standards
(F1351).
1TABLE 1 Addition of sizing dispersion Image analyses test, Toner
Dispersion weight % on dry pulp lost area in mm.sup.2 no. 1 1.8 5.9
no. 1 2.0 7.1 no. 1 2.2 7.5 no. 2 1.8 8.2 no. 2 2.0 7.7 no. 2 2.2
8.4
* * * * *