[0001] The present invention relates to a filler comprising clay and cellulose derivative.
The invention further relates to a method of making the filler, the use of the filler
in papermaking, a process for papermaking in which the filler is used as an additive
as well as paper comprising the filler.
Background of the Invention
[0002] In the production of filled paper, an aqueous suspension containing cellulosic fibres,
fillers and additives, referred to as the stock, is fed into a headbox which ejects
the stock onto a forming wire, Water is drained from the stock through the forming
wire so that a wet web of paper is formed on the wire, and the web is further dewatered
and dried in the drying section of the paper machine.
[0003] Highly filled paper is an established trend in the paper industry, not only due to
the savings in the decreased use of fibre, but also due to improved product quality,
such as higher opacity and better printability. For super calandered paper (SC paper)
and many paper grades containing mechanical fibres, kaolin clay is the most commonly
used filler. The day particles have a flake or plate shape, and at calandering the
flakes are uniformly oriented, giving a high gloss and smoothness to the paper. The
amount of filler can be as high as 30% or more.
[0004] A high degree of filler causes a decrease in paper strength as well as linting and
dusting. A rule of thumb at filler usage in paper is that a 10% increase in filler
content decreases the strength by 20%. Problems with linting and dusting occur, as
small fibre fragments and fillers are not properly bound into the paper. This can
give a specific problem at rotogravure printing of SC paper, called missing dots,
when ink is missing in dots in the print.
[0005] Addition of a binding agent can increase the strength of the paper as well as decrease
the linting and dusting. Among other materials starch has been used as a binding agent.
However, in SC paper making, the calandering of the paper is done at a load of 100-350
kN/m. Starch makes the paper brittle and it can break at such heavy loads. Starch
also makes the paper denser already prior to calandering. Therefore, no starch or
small additions (1-2 kg/tonne dry paper) is used in SC paper making.
[0006] Conventional CMC is sometimes added to the wet end as a strength additive. However,
then the problem is that dewatering is slowed down considerably. A third possibility,
synthetic strength additives, can be used but they are often quite expensive.
[0007] For all paper grades with high filler loadings, paper strength, drainage and filler
retention are important issues. Sometimes size is added, and then also size consumption
is higher when the filler loadings are increased and/or when starch is not used.
[0008] EP 758695 A2 discloses a water-dispersible sheet and a cigarette using the sheet. The sheet comprises
a water-resolvable base paper made from fibrous raw materials and a water-dispersilble
coating layer containing water-soluble polymer and an alkaline compound. The water-resolvable
base paper is made from a mixture of water-dispersible fibres and fibrous carboxymethyl
cellulose acid or fibrous carboxyethyl cellulose acid.
[0009] US 5,759,346 describes a method of improving strength and reducing lint and dust in the production
of tissue paper. The filler is a kaolin clay which has been pre-treated with a cationic
starch.
[0010] WO 01/86067 describes a method for pre-treating a filler with a hydrophobic polymer, which is
a synthetic polymer comprising acrylate and styrene monomers. The use of the pre-treated
filler improves wet strength and reduces the linting of the paper.
[0011] Furthermore,
WO 95/13324 refers to calcium carbonate treated with a cellulose derivative such as sodium carboxymethyl
cellulose ("CMC") having a degree of substitution of 0.70. Said treated calcium carbonate
is used as filler in alkaline papermaking suspensions whereby the brightness of the
paper is increased.
[0012] There is still need for a filler which provides an improved papermaking process and
better properties of the paper produced. It would be desired to provide a filler which
renders possible production of highly filled paper showing excellent printing and
mechanical properties. It would also be desirable to provide a filler which is compatible
with drainage and retention aids, and hereby leads to good drainage, retention and
paper machine runnability. It would also be desirable to provide a simple and efficient
process for producing a filler showing the above characteristics.
Summary of the Invention
[0013] The present invention generally relates to a filler comprising clay and cellulose
derivative. The present invention further generally relates to a filler comprising
clay and carboxymethyl cellulose derivate. The present invention also generally relates
to a method of making the filler by mixing clay with a cellulose derivative, the use
of the filler as an additive in papermaking as well as paper comprising the filler.
The invention further generally relates to papermaking process in which the filler
is introduced into an aqueous cellulosic suspension.
[0014] More specifically, the invention relates to a filler comprising day and a cellulose
derivative having a degree of substitution of net anionic groups from 0.05 up to 0.65
and containing cationic groups. The invention also relates to a filler comprising
clay and a cellulose derivative having a degree of substitution of carboxyalkyl groups
from 0.05 up to 0.65 and containing cationic groups. The invention further relates
to a method of producing a filler which comprises mixing clay with a cellulose derivative
having a degree of substitution of net ionic groups from 0.05 up to 0.65 and containing
cationic groups. The invention also relates to a method of producing a filler which
comprises mixing clay with a cellulose derivative having a degree of substitution
of carboxyalkyl groups from 0.05 up to 0.65 and containing cationic groups. The invention
further relates to a filler obtainable by these methods. The invention further relates
to a papermaking process which comprises providing an aqueous suspension containing
cellulosic fibres, introducing into the suspension a filler comprising clay and cellulose
derivative having a degree of substitution of net ionic groups from 0.05 up to 0.65
and containing cationic groups, and dewatering the suspension to form a web or sheet
of paper. The invention also relates to a papermaking process which comprises providing
an aqueous suspension containing cellulosic fibres, introducing into the suspension
a filler comprising clay and cellulose derivative having a degree of substitution
of carboxyalkyl groups from 0.05 up to 0.65 and containing cationic groups and dewatering
the suspension to form a web or sheet of paper. In the papermaking process, the filler
can be introduced into the cellulosic suspension by adding the clay and cellulose
derivative separately or together as a single composition.
Detailed Description of the Invention
[0015] The present invention provides a new filler that is suitably for use in papermaking.
It has surprisingly been found that the filler according to the invention makes it
possible to reduce some of the problems associated with fillers commonly used in papermaking
and incorporated in paper. More specifically, by employing the filler of this invention
in papermaking processes it is possible to reduce the linting and dusting of paper
and provide paper with excellent printing and mechanical properties. Additional advantages
shown by the present invention include good and/or improved dewatering and fines retention,
which leads to benefits in terms of paper machine runnability.
[0016] When using the filler in the making of SC paper and newsprint paper it has been observed
that the present invention makes it possible to reduce the linting and dusting of
the paper without adversely affecting the mechanical properties of the paper produced
and without decreasing the dewatering and retention of fines and filler in the papermaking
process.
[0017] According to the present invention it has been observed that the cellulose derivative
can be mixed with and more effectively be adsorbed on or attached to the clay surface
during simple processing. The filler of the invention can be regarded as a modified
filler, or cellulose derivative-treated filler.
[0018] According to the present invention it has been found that very good results can be
obtained by adding the clay and cellulose derivative to a cellulosic suspension together
in a pre-mixed or pre-treated form. The pre-treatment of the day with the cellulose
derivative provides a convenient way of separately processing only one component of
the cellulosic suspension to produce a modified filler, which can be used instead
of or partly replacing conventional fillers. Without being bound to any theory, it
is believed that cellulose derivative is adsorbed to the day when mixing the components,
which adsorption may also take place
in situ in the cellulosic suspension when separately adding the components,
[0019] The filler according to the invention comprises a clay and a cellulose derivative.
Examples of suitable clays include those having a flake or plate like shape. Examples
of suitable clays include talc, hydrotalcit, kaolin, calcinated clay, bentonite or
mixtures thereof, preferably kaolin, calcinated clay or talc, most preferably kaolin
and calcinated day. Examples of suitable clays include those having a specific surface
area in the range from 2 m
2/g to 800 m
2/g, suitably from 2 m
2/g to 600 m
2/g, most preferably from 5 m
2/g to 20 m
2/g. The particle size is usually from 0.1 µm to 50 µm, preferably from 0.1 µm to 5
µm and most preferably from 0.8 µm to 3 µm.
[0020] Natural kaolin clay has the chemical formula Al
2O
3 * 2SiO
2 * 2H
2O. Kaolin clays include so called dioctahedral 1:1 aluminium silicates. The kaolin
clay usually have a particle size of from 1µm to 5µm, preferably from 1µm to 3µm.
The kaolin clay usually has a surface area of from 3 m
2/g to 10 m
2/g, suitably from 5 m
2/g to 8 m
2/g.
[0021] Calcinated clay has the formula Al
2O
3 * SiO
2. The calcinated clay usually has a specific surface area of from 10 m
2/g to 20 m
2/g, suitably from 15 m
2/g to 17 m
2/g. The calcinated clay usually has a particle size in the range of from 0.8 µm to
4 µm, preferably from 0.8 µm to 2µm.
[0022] The filler according to the invention further comprises a cellulose derivative. It
is preferred that the cellulose derivative is water-soluble or at least partly water-soluble
or water-dispersible, preferably water-soluble or at least partly water-soluble. The
cellulose derivative is ionic. The cellulose derivative can be cationic or amphoteric,
preferably amphoteric. Examples of suitable cellulose derivatives include cellulose
ethers, e.g. amphoteric cellulose ethers. The cellulose derivative has ionic or charged
groups, or substituents. Examples of suitable ionic groups include anionic and cationic
groups. Examples of suitable anionic groups include carboxylate, e.g. carboxyalkyl,
sulphonate, e.g. sulphoalkyl, phosphate and phosphonate groups in which the alkyl
group can be methyl, ethyl propyl and mixtures thereof, suitably methyl; suitably
the cellulose derivative contains an anionic group comprising a carboxylate group,
e.g. a carboxyalkyl group. The counter-ion of the anionic group is usually an alkali
metal or alkaline earth metal, suitably sodium.
[0023] Examples of suitable cationic groups of cellulose derivatives according to the invention
include salts of amines, suitably salts of tertiary amines, and quaternary ammonium
groups, preferably quaternary ammonium groups. The substituents attached to the nitrogen
atom of amines and quaternary ammonium groups can be same or different and can be
selected from alkyl, cycloalkyl, and alkoxyalkyl, groups, and one, two or more of
the substituents together with the nitrogen atom can form a heterocyclic ring. The
substituents independently of each other usually comprise from 1 to 24 carbon atoms,
preferably from 1 to 8 carbon atoms. The nitrogen of the cationic group can be attached
to the cellulose or derivative thereof by means of a chain of atoms which suitably
comprises carbon and hydrogen atoms, and optionally O and/or N atoms. Usually the
chain of atoms is an alkylene group with from 2 to 18 and suitably 2 to 8 carbon atoms,
optionally interrupted or substituted by one or more heteroatoms, e.g. 0 or N such
as alkyleneoxy group or hydroxy propylene group. Preferred cellulose derivatives containing
cationic groups include those obtained by reacting cellulose or derivative thereof
with a quaternization agent selected from 2, 3-epoxypropyl trimethyl ammonium chloride.
3-chloro-2-hydroxypropyl trimethyl ammonium chloride and mixtures thereof.
[0024] The cellulose derivatives of this invention can contain non-ionic groups such as
alkyl or hydroxy alkyl groups, e.g. hydroxymeyhyl, hydroxyethyl, hydroxypropyl, hydroxylbutyl
and mixtures thereof, e.g. hydroxyethyl methyl, hydroxypropyl methyl, hydroxybutyl
methyl, hydroxyethyl ethyl, hydroxypropoyl and the like. In a preferred embodiment
of the invention, the cellulose derivative contains both ionic groups and non-ionic
groups.
[0025] Examples of suitable cellulose derivatives according to the invention include carboxyalkyl
celluloses, e.g. carboxymethyl cellulose carboxyethyl cellulose, carboxypropyl cellulose,
sulphoethyl carboxymethyl cellulose, carboxymethyl hydroxyethyl cellulose ("CM-HEC"),
carboxymethyl cellulose wherein the cellulose is substituted with one or more non-ionic
substituents, preferably carboxymethyl cellulose ("CMC"). Examples of suitable cellulose
derivatives and methods for their preparation include those disclosed In
U.S. Pat. No. 4,940,785, which is hereby incorporated herein by reference.
[0026] The terms "degree of substitution" or "DS", as used herein, mean the number of substituted
ring sites of the beta-anhydroglucose rings of the cellulose derivative. Since there
are three hydroxyl groups on each anhydroglucose ring of the cellulose that are available
for substitution, the maximum value of DS is 3.0. According to one embodiment of the
invention, the cellulose derivative has a degree of substitution of net ionic groups
("DS
NI") from 0.05 up to 0.65, I.e. the cellulose derivative has an average degree of net
ionic substitution per glucose unit from 0.05 up to 0.65. The net ionic substitution
can be net anionic, or net cationic. When the net ionic substitution is net anionic,
there is a net excess of anionic groups (net anionic groups = the average number of
anionic groups minus the average number of cationic groups per glucose unit) and DS
NI is the same as the degree of substitution of net anionic groups ("DS
NA"). When the net ionic substitution is net cationic, there is a net excess of cationic
groups (net cationic groups = the average number of cationic groups minus the average
number of anionic groups, if any, per glucose unit) and DS
NI is the same as the degree of substitution of net cationic groups ("DS
NC"). According to another preferred embodiment of the invention, the cellulose derivative
has a degree of substitution of carboxyalkyl groups ("DS
CA") from 0.05 up to 0.65. i.e. the cellulose derivative has an average degree of carboxyalkyl
substitution per glucose unit from 0.05 up to 0.65. The carboxyalkyl groups are suitably
carboxymethyl groups and then DS
CA referred to herein is the same as the degree of substitution of carboxymethyl groups
('DS
CM"). According to these embodiments of the invention, DS
NI, DS
NA, DS
NC and DS
CA independently of each other are usually up to 0.60, suitably up to 0.50. preferably
up to 0.45 and more preferably up to 0.40, whereas DS
NI, DS
NA, DS
NC and DS
CA independently of each other are at least 0.05, preferably at least 0.10 and more
preferably at least 0.15. The ranges of DS
NI, DS
NA, DS
NC and DS
CA independently of each other are usually from 0.05 to 0.60, suitably from 0.05 to
0.50, preferably from 0.10 to 0.45 and more preferably from 0.15 to 0.40.
[0027] Cellulose derivatives that are amphoteric usually have a degree of anionic substitution
("DS
A") in the range of from 0.01 to 1.0 as long as DS
NI and DS
NA are as defined herein from 0.05, preferably from 0.10, and more preferably from 0.15
and suitably up to 0.75, preferably up to 0.5, and more preferably up to 0.4. Cellulose
derivatives that are cationic or amphoteric can have a degree of cationic substitution
("DS
C") in the range of from 0.01 to 1.0 as long as DS
NI and DS
NC are as defined herein; suitably from 0.02, preferably from 0.03, and more preferably
from 0.05 and suitably up to 0.75, preferably up to 0.5. and more preferably up to
0.4. The cationic groups are suitably quaternary ammonium groups and then DS
C referred to herein is the same as the degree of substitution of quaternary ammonium
groups ("DS
QN"). For amphoteric cellulose derivatives of this invention DS
A or DS
C can of course be higher than 0.65 as long as DS
NA and DS
NC, respectively, are as defined herein. For example, if DS
A is 0.75 and DS
C is 0.15, then DS
NA is 0.60.
[0028] Examples of suitable cellulose derivatives having degrees of substitution as defined
above include the water-soluble low DS carboxyalkyl cellulose derivatives. The water-soluble
cellulose derivatives suitably has a solubility of at least 85 % by weight based on
total weight of dry cellulose derivative, in an aqueous solution, preferably at least
90 % by weight, more preferably at least 95 % by weight, and most preferably at least
98 % by weight
[0029] The cellulose derivative usually has an average molecular weight which is at least
20,000 Dalton, preferably at least 50,000 Dalton, and the average molecular weight
is usually up to 1,000,000 Dalton, preferably up to 500,000 Dalton.
[0030] Preferably, in the filler according to the invention, the cellulose derivative is
at least in part adsorbed on or attached to the clay. Suitably, at least 10 % by weight,
preferably at least 30 % by weight, more preferably at least 45 % by weight and most
preferably at least 60 % by weight of the cellulose derivate is adsorbed on or attached
to the clay.
[0031] The filler according to the invention usually has a clay content of at least 0.0001
% by weight; the day content can be from 0.0001 to 99.5 % by weight, suitably from
0.1 to 90 % by weight, and preferably from 60 to 80 % by weight, based on the weight
of the solids of the filler, i.e. based on the dry weight of the filler. The filler
usually has a cellulose derivative content of at least 0.01 % by weight; the cellulose
derivative content can be from 0.01 to 30 % by weight, suitably from 0.1 to 20 % by
weight, and preferably from 0.3 to 10 % by weight, based on the weight of the solids
of the filler.
[0032] The filler according to the invention can be supplied as a solid material that can
be essentially free of water. It can also be supplied as an aqueous composition. The
content of aqueous phase, or water, can vary within wide limits, depending on the
method of production and intended use.
[0033] The present invention also relates to a method of making a filler which comprises
mixing a cellulose derivative, e.g. any one of the cellulose derivatives defined herein,
with clay. The cellulose derivative and clay are suitably used in amounts so as to
provide a filler according to the invention having contents of cellulose derivative
and clay as defined herein.
[0034] The cellulose derivative and clay used can be present as solids or in aqueous compositions,
and mixtures thereof. The clay is suitably present as a finely divided material. The
mixing can be achieved by adding the cellulose derivative to the filler, or vice versa,
in a batch, semi-batch or continuous process. According to a preferred embodiment
of the invention, the cellulose derivative is added as a solid to an aqueous composition
of the clay and the composition obtained is then suitably subjected to effective dispersing
to dissolve the cellulose derivative. Preferably, the mixing is carried out by first
forming a neutral to alkaline aqueous phase, suitably an aqueous solution, of cellulose
derivative which is then mixed with an aqueous composition of clay. Prior to mixing
with the clay, the aqueous phase of cellulose derivative can be subjected to pre-treatment,
e.g. homogenisation, centrifugation and/or filtration, for example for separating
undissolved cellulose derivative, if any, from the aqueous phase.
[0035] Preferably, the cellulose derivative is mixed with the clay to allow at least part
of the cellulose derivative to adsorb on or attach to the clay, preferably so that
it is hardly removed from the material by dilution with water. This can be accomplished
by carrying out mixing under a period of time that is sufficient long to allow the
adsorption on attachment. Suitably the mixing time is at least 1 min, preferably at
least 5 mln, more preferably at least 10 min and most preferably at least 20 min.
Mixing periods of even several hours (1 - 10 h) are possible if it is desired to reach
a high degree of attachment. Suitably, at least 10 % by weight, preferably at least
30 % by weight, more preferably at least 45 % by weight and most preferably at least
60 % by weight of the cellulose derivate is transferred from the aqueous phase and
adsorbed on or attached to the clay or other components present in the clay.
[0036] The pH of the aqueous phase of cellulose derivative is usually adjusted for sorption
of the specific cellulose derivative used at a value from 4 to 13, preferably from
6 to 10, more preferably from 7 to 8.5. A suitable base or acid can be used for adjusting
the pH. Examples of suitable bases include bicarbonates and carbonates of alkali metals
and alkali metal hydroxides, suitably sodium bicarbonate, sodium carbonate and sodium
hydroxide. Examples of suitable acids include mineral acids, organic acids and acid
salts, suitably sulphuric acid and its acid salts, such as alum. In general, at a
lower pH. i.e. a pH from 4.0 to neutral, adsorption of the cellulose derivative is
higher but solubility is decreased, whereas at higher pH the adsorption is reduced
but solubility is increased.
[0037] The temperature is not critical in operations in non-pressurized conditions the temperature
is typically from 10 to 100 °C, preferably from 20 to 80 °C. However, higher temperatures
are more favourable, suitably the temperature of the aqueous composition during mixing
is from 30 up to 70 °C. more preferably from 40 up to 60 °C.
[0038] The filler obtained by the method of the invention can be used as such, for example
in papermaking. If present as an aqueous composition, it can be used directly or it
can be dried, if desired, for example to simplify shipping.
[0039] The present invention also relates to a process for the production of paper which
comprises providing an aqueous suspension containing cellulosic fibres ("cellulosic
suspension"), introducing into the cellulosic suspension a filler, e.g. any one of
the fillers defined herein, and dewatering the cellulosic suspension to form a web
or sheet of paper. Preferably, the filler is introduced into the cellulosic suspension
by adding it as a single composition. Alternatively, the clay and cellulose derivative
(e.g. any one of the cellulose derivatives defined herein) can be separately added
to the cellulosic suspension and the filler is formed
in situ in the cellulosic suspension.
[0040] The filler according to the invention can be added to the cellulosic suspension in
amounts which can vary within wide limits depending on, inter alia, type of cellulosic
suspension, type of paper produced, point of addition, etc. The filler is usually
added in an amount within the range of from 1 to 50 % by weight, suitably from 5 to
40 % by weight, and usually from 10 to 30 % by weight, based on the weight of dry
fibres. Accordingly, the paper according to the invention usually has a content of
filler of this invention within the range of from 1 to 50 % by weight, suitably from
5 to 40 % by weight, and usually from 10 to 30 % by weight, based on the weight of
dry fibres.
[0041] In the process, other components may of course be introduced into the cellulosic
suspension. Examples of such components include conventional fillers, optical brightening
agents, sizing agents, coagulant flocculants, drainage and retention aids, dry strength
agents, wet strength agents, etc. Examples of suitable conventional fillers include
Kaolin, china clay titanium dioxide, gypsum, talc, natural and synthetic calcium carbonates,
e.g. chalk, ground marble and precipitated calcium carbonate, hydrogenated aluminum
oxides (aluminum trihydroxides), calcium sulphate, barium sulphate, calcium oxalate,
etc. When using the filler according to the invention together with conventional filler,
the filler according to the invention can be present in an amount of at least 1 %
by weight, suitably at least 5 % by weight, preferably at least 10 % by weight, more
preferable at least 20 % by weight, and suitably up to 99 % by weight, based on the
dry weight of all fillers. Examples of suitable sizing agents include non-cellulose-reactive
sizing agents, e.g. rosin-based sizing agents like rosin-based soaps, rosin-based
emulsions/dispersions, and cellulose-reactive sizing agents, e.g. emulsions/dispersions
of acid anhydrides like alkenyl succinic anhydrides (ASA), alkenyl and alkyl kelene
dimers (AKD) and multimers. Examples of suitable drainage and retention aids Include
organic polymeric products, e.g. cationic, anionic and non-ionic polymers including
cationic polyethylene imines, cationic, anionic and non-ionic polyacrylamides, cationic
polyamines, cationic starch, and cationic guar; inorganic materials, e.g. aluminium
compounds, anionic microparticulate materials like colloidal silica-based particles,
clays of smectite type, e.g. bentonite, montmorillonite; colloidal alumina, and combinations
thereof. Examples of suitable combinations of drainage and retention aids include
cationic polymers and anionic microparticulate materials, e.g. cationic starch and
anionic colloidal silica-based particles, cationic polyacrylamide and anionic colloidal
silica-based particles as well as cationic polyacrylamide and bentonite or montmorllonite.
Examples of suitable wet strength agents include polyamines and polyaminoamides. Paper
containing filler according to the invention and cationic starch shows very good strength
properties.
[0042] The term "paper", as used herein, include not only paper and the production thereof,
but also other cellulosic fibre-containing sheet or web-like products, such as for
example board and paperboard, and the production thereof. The process can be used
in the production of paper from different types of aqueous suspensions of cellulosic
(cellulose-containing) fibres and the suspensions should suitably contain at least
25% by weight and preferably at least 50% by weight of such fibres, based on a dry
substance. The cellulosic fibres can be based on virgin fibres and/or recycled fibres,
including fibres of wood or annual or perennial plants. The cellulosic suspension
can be wood-containing or wood-free, and it can be based on fibres from chemical pulp
such as sulphate, sulphite and organosolve pulps, mechanical pulp such as thermo-mechanical
pulp, chemo-thermo-mechanical pulp, refiner pulp and ground wood pulp, from both hardwood
and softwood, and can also be based on recycled fibres, optionally from de-inked pulps,
and mixtures thereof. The cellulosic suspension suitably has a pH in the acid to neutral
to alkaline range, e.g. from 4 to 10, preferably from 5 to 8.
[0043] The invention is further illustrated in the following Examples which, however, are
not intended to limit the same. Parts and % relates to parts by weight and % by weight,
respectively, unless otherwise stated.
Example 1
[0044] Fillers according to the invention have been prepared by treating clay with cellulose
derivatives. Cellulose derivatives used were carboxymethyl cellulose ("CMC") (according
to prior art) and quaternary ammonium carboxymethyl cellulose ("QN-CMC") (according
to invention). The mole weight of the CMC was <200,000 Dalton. The clay used in the
examples was kaolin clay.
[0045] The types of CMC used to treat the clay were the following:
CMC 0.35 |
DSCA=0.35 (prior art) |
CMC 0.5 |
Gabrosa PA 947 Akzo Nobel DSCA=0.5 (prior art) |
QN-CMC |
DSCA=0.4 and DSQN=0.17 (invention) |
Preparation of CMC-modified clay;
[0046] CMC was first dissolved into water to a consistency of 0.5 % by weight. Thereafter,
the CMC composition was added to the clay filler slurry and mixed during 35 to 40
minutes at a temperature of 50 °C.
Example 2
[0047] In the following example, SC paper (super calandered) was prepared using kaolin clay
treated with carboxymethyl cellulose (CMC). The CMC used was QN-CMC (invention) and
CMC 0.5 (prior art) as described in Example 1. The preparation of the CMC-modified
clay has been done as described in Example 1. The SC paper was then tested for ash
content, total retention and linting.
[0048] The paper sheets were produced from a SC pulp furnish consisting of 80% mechanical
pulp and 20% chemical pulp. The furnish suspension contained 50% day filler, had a
consistency of 0.5% by weight, pH of 7.7 and a conductivity of 0.3 mS/cm. To the pulp
suspension or to the clay slurry an amount of 2% CMC/tonne dry clay was added. A retention
system containing cationic polymer (Eka retention polymer PL 1510) and silica particles
(Eka retention silica NP 442) was also added. Both the polymer and silica particles
were added in an amount of 0.2 kg/tonne dry fibres. The addition sequence was the
following:
Addition of separate CMC when used: |
0 sec. |
Addition of filler: |
15 sec. |
Addition of retention polymer: |
30 sec. |
Addition of retention silica: |
45 sec. |
Sheet making: |
105 sec. |
[0049] The paper sheets prepared in the following examples were made according to standard
using a Dynamical Sheet Former ("Formette", CTP Grenoble).
[0050] The paper sheets were tested for retention and ash content, see table 1. Separate
CMC 0.5 means that the CMC 0.5 was added before the untreated clay.
Table 1
Test No. |
Type of CMC and addition |
Ash level [%] |
Total retention [%] |
1 |
QN-CMC on clay (invention) |
39.8 |
83.0 |
2 |
CMC 0.5 on clay (prior art) |
34.2 |
76.0 |
3 |
Separate CMC 0.5 (prior art) |
36.1 |
78.2 |
[0051] The sheets were also tested for linting, see table 2. Linting is measured by applying
a well defined adhesive tape to an area of the paper surface and then mechanically
draw off the tape at a specific force and angle. The amount of lint, fibre fragments
and filler, present on the tape is then measured. This measurement was also made after
calandering the paper sheets.
Table 2
Test No. |
Type of CMC and addition |
Linting [mg] No calandering |
Linting [mg] After calandering |
1 |
QN-CMC on clay (invention) |
2.5 |
4.5 |
2 |
CMC 0.5 on clay (prior art) |
4.2 |
9.4 |
3 |
Separate CMC 0.5 (prior art) |
4.3 |
10.0 |
Example 3
[0052] In this example, newsprint paper was prepared using a clay treated with CMC. The
CMC used was CMC 0.35 (prior art) and CMC 0,5 (prior art as defined in example 1.
The clay used was a kaolin clay. The preparation of the CMC-modified day ha been done
as described in Example 1. Tensile strength index was measured on the paper and the
results are displayed in table 3.
[0053] Paper sheets were produced from a newsprint pulp furnish consisting of 75% mechanical
pulp and 25% de-inked newsprint pulp. The furnish suspension contained 10% calcinated
clay filler, had a consistency of 0.3%, pH of 7.2 and conductivity of 1.0 mS/cm. To
the pulp suspension or to the clay slurry an amount of 2% CMC/tonne dry clay was added.
The addition sequence was the following:
Addition of separate CMC when used: |
0 sec. |
Addition of filler: |
15 sec. |
Sheet making: |
105 sec. |
[0054] The paper sheets prepared in the following examples were made according to standard
using a Dynamical Sheet Former ("Formette". CTP Grenoble).
[0055] Separate CMC 0.5 means that the CMC 0.5 was added before the untreated clay.
Table 3
Test No. |
Type of CMC and addition |
Tenseile index [kNm/kg] |
1 |
CMC 0.35 on clay (prior art) |
31.5 |
2 |
CMC 0.5 on clay (prior art) |
29.3 |
3 |
Separate CMC 0.5 (prior art) |
29.6 |
Example 4
[0056] A SC paper furnish was prepared using a clay treated with CMC. Three different kinds
of CMC were used to prepare the filler, CMC 0.35 (prior art), CMC 0.5 (prior art)
and QNC-CMC (invention). The types of CMC are as defined in example 1. The preparation
of the CMC-modified clay have been done as described in Example 1, but the CMC and
clay filler slurry has been mixed for 15 minutes or 4 hours respectively.
[0057] The SC paper furnish that was used consisted of 80% mechanical pulp and 20% chemical
pulp. The furnish suspension contained 50% clay filler, had a consistency of 0.25%,
pH of 7.8 and conductivity of 0.3 mS/cm. To the clay slurry an amount of 2% CMC/tonne
dry clay was added and to the pulp suspension a retention system containing cationic
polymer (Eka retention polymer PL 1510) and silica particles (Eka retention silica
NP 780) was added. Both the polymer and silica particles were added in an amount of
1 kg/tonne dry fibres. The addition sequence was the following:
Addition of CMC treated filler: |
0 sec. |
Addition of retention polymer: |
15 sec. |
Addition of retention silica: |
30 sec. |
Dewatering: |
45 sec. |
[0058] The dewatering values are presented in table 4,
Table 4 5
Test No. |
Type of CMC |
Pre-treatment of filler for 4 hours Dewatering time (s) |
Pre-treatment of filler for 15 minutes Dewatering time (s) |
1 |
CMC 0.35 (prior art) |
45.0 |
48.8 |
2 |
QN-CMC (invention) |
40.4 |
33.0 |
3 |
CMC 0.5 (prior art) |
64.7 |
58.7 |
1. A process for the production of paper which comprises providing an aqueous suspension
containing cellulosic fibres, introducing into the suspension a filler comprising
in pre-mixed form a clay and cellulose derivative having a degree of substitution
of net ionic groups from 0.05 up to 0.65 wherein the cellulose derivative contains
cationic groups, and dewatering the suspension to form a web or sheet of paper.
2. A filler comprising clay and cellulose derivative having a degree of substitution
of net ionic groups from 0.05 up to 0.65 wherein the cellulose derivative contains
cationic groups.
3. A method of making a filler which comprises mixing clay with a cellulose derivative
having a degree of substitution of net ionic groups from 0.05 up to 0.65, wherein
the cellulose derivative contains cationic groups.
4. The process according to claim 1, the filler according to claim 2, or the method according
to claim 3, characterised in that the degree of substitution is at least 0.10.
5. The process according to claim 1 or 4, the filler according to claim 2 or 4, or the
method according to claim 3 or 4, characterised in that the degree of substitution is from 0.15 to 0.40.
6. The process according to any one of claims 1, 4 and 5, the filler according to any
one of claims 2, 4 and 5, or the method according to any one of claims 3 to 5, characterised in that the cellulose derivative is a cellulose ether.
7. The process according to any one of claims 1 and 4 to 6, the filler according to any
one of claims 2 and 4 to 6, or the method according to any one of claims 3 to 6, characterised in that the cellulose derivative contains carboxymethyl groups.
8. The process according to any one of claims 1 and 4 to 7, the filler according to any
one of claims 2 and 4 to 7, or the method according to any one of claims 3 to 7, characterised in that the cellulose derivative contains quaternary ammonium groups.
9. The process according to any one of claims 1 and 4 to 7, characterised in that the cellulose derivative is anionic.
10. The process according to any one of claims 1 and 4 to 8, the filler according to any
one of claims 2 and 4 to 8, or the method according to any one of claims 3 to 7 and
9, characterised in that the cellulose derivative is amphoteric.
11. The process according to any one of claims 1 and 4 to 10, the filler according to
any one of claims 2, 4 to 8 and 10, or the method according to any one of claims 3
to 8 and 10, characterised in that the cellulose derivative is at least partly water soluble.
12. The process according to any one of claims 1 and 4 to 11, the filler according to
any one of claims 2, 4 to 8, 10 and 11, or the method according to any one of claims
3 to 8, 10 and 11, characterised in that the filler has a cellulose derivative content from 0.3 to 10 % by weight, based on
the weight of the solids of the filler.
13. The process according to any one of claims 1 and 4 to 12, the filler according to
any one of claims 2, 4 to 8 and 10 to 12, or the method according to any one of claims
3 to 8 and 10 to 12, characterised in that the filler has a clay content from 60 to 80 % by weight, based on the weight of the
solids of the filler.
14. The process according to any one of claims 1 and 4 to 13, the filler according to
any one of claims 2, 4 to 8 and 10 to 13, or the method according to any one of claims
3 to 8 and 10 to 13, characterised in that the clay is a kaolin clay.
15. The process according to any one of claims 1 and 4 to 14, the filler according to
any one of claims 2, 4 to 8 and 10 to 14, or the method according to any one of claims
3 to 8 and 10 to 14, characterised in that the clay is calcinated clay.
16. The process according to any one of claims 1 and 4 to 15, the filler according to
any one of claims 2, 4 to 8 and 10 to 15, or the method according to any one of claims
3 to 8 and 10 to 15, characterised in that the clay is talc.
17. Paper comprising a filler according to any one of claims 2, 4 to 8 and 10 to 16.
18. The paper according to claim 16, characterised in that the total filler content of the paper is from 5 to 40 % by weight, based on dry paper.
19. The process according to any one of claims 1 and 4 to 16, characterised in that the filler is added in an amount of from 5 to 30 % by weight, based on dry fibre.
1. Verfahren zur Papierherstellung, das das Bereitstellen einer wässrigen, Cellulosefasern
enthaltenden Suspension, das Einbringen eines Füllstoffes, umfassend Ton und ein Cellulose-Derivat
mit einem Substitutionsgrad ionischer Nettogruppen von 0,05 bis 0,65 in vorgemischter
Form in die Suspension umfasst, wobei das Cellulose-Derivat kationische Gruppen enthält,
und das Entwässern der Suspension, um eine Papierbahn oder einen Papierbogen herzustellen,
umfasst.
2. Füllstoff umfassend Ton und ein Cellulose-Derivat mit einem Substitutionsgrad ionischer
Nettogruppen von 0,05 bis 0,65, wobei das Cellulose-Derivat kationische Gruppen enthält.
3. Verfahren zur Herstellung eines Füllstoffes, das das Mischen von Ton mit einem Cellulose-Derivat
mit einem Substitutionsgrad ionischer Nettogruppen von 0,05 bis 0,65 umfasst, wobei
das Cellulose-Derivat kationische Gruppen enthält.
4. Verfahren nach Anspruch 1, Füllstoff nach Anspruch 2 oder Verfahren nach Anspruch
3, dadurch gekennzeichnet, dass der Substitutionsgrad mindestens 0,10 beträgt.
5. Verfahren nach Anspruch 1 oder 4, Füllstoff nach Anspruch 2 oder 4 oder Verfahren
nach Anspruch 3 oder 4, dadurch gekennzeichnet, dass der Substitutionsgrad von 0,15 bis 0,40 beträgt.
6. Verfahren nach einem der Ansprüche 1, 4 und 5, Füllstoff nach einem der Ansprüche
2, 4 und 5 oder Verfahren nach einem der Ansprüche 3 bis 5, dadurch gekennzeichnet, dass das Cellulose-Derivat ein Celluloseether ist.
7. Verfahren nach einem der Ansprüche 1 und 4 bis 6, Füllstoff nach einem der Ansprüche
2 und 4 bis 6 oder Verfahren nach einem der Ansprüche 3 bis 6, dadurch gekennzeichnet, dass das Cellulose-Derivat Carboxymethylgruppen enthält.
8. Verfahren nach einem der Ansprüche 1 und 4 bis 7, Füllstoff nach einem der Ansprüche
2 und 4 bis 7, oder Verfahren nach einem der Ansprüche 3 bis 7, dadurch gekennzeichnet, dass das Cellulose-Derivat quaternäre Ammoniumgruppen enthält.
9. Verfahren nach einem der Ansprüche 1 und 4 bis 7, dadurch gekennzeichnet, dass das Cellulose-Derivat anonisch ist.
10. Verfahren nach einem der Ansprüche 1 und 4 bis 8, Füllstoff nach einem der Ansprüche
2 und 4 bis 8 oder Verfahren nach einem der Ansprüche 3 bis 7 und 9, dadurch gekennzeichnet, dass das Cellulose-Derivat amphoter ist.
11. Verfahren nach einem der Ansprüche 1 und 4 bis 10, Füllstoff nach einem der Ansprüche
2, 4 bis 8 und 10 oder Verfahren nach einem der Ansprüche 3 bis 8 und 10, dadurch gekennzeichnet, dass das Cellulose-Derivat mindestens teilweise wasserlöslich ist.
12. Verfahren nach einem der Ansprüche 1 und 4 bis 11, Füllstoff nach einem der Ansprüche
2, 4 bis 8, 10 und 11 oder Verfahren nach einem der Ansprüche 3 bis 8, 10 und 11,
dadurch gekennzeichnet, dass der Füllstoff einen Cellulose-Derivatgehalt von 0,3 bis 10 Gew.% hat, basierend auf
dem Gewicht der Feststoffe des Füllstoffes.
13. Verfahren nach einem der Ansprüche 1 und 4 bis 12, Füllstoff nach einem der Ansprüche
2, 4 bis 8 und 10 bis 12 oder Verfahren nach einem der Ansprüche 3 bis 8 und 10 bis
12, dadurch gekennzeichnet, dass der Füllstoff einen Tongehalt von 60 bis 80 Gew.% hat, basierend auf dem Gewicht
der Feststoffe des Füllstoffes.
14. Verfahren nach einem der Ansprüche 1 und 4 bis 13, Füllstoff nach einem der Ansprüche
2, 4 bis 8 und 10 bis 13 oder Verfahren nach einem der Ansprüche 3 bis 8 und 10 bis
13, dadurch gekennzeichnet, dass der Ton Kaolin ist.
15. Verfahren nach einem der Ansprüche 1 und 4 bis 14, Füllstoff nach einem der Ansprüche
2, 4 bis 8 und 10 bis 14 oder Verfahren nach einem der Ansprüche 3 bis 8 und 10 bis
14, dadurch gekennzeichnet, dass der Ton kalzinierter Ton ist.
16. Verfahren nach einem der Ansprüche 1 und 4 bis 15, Füllstoff nach einem der Ansprüche
2, 4 bis 8 und 10 bis 15 oder Verfahren nach einem der Ansprüche 3 bis 8 und 10 bis
15, dadurch gekennzeichnet, dass der Ton Talk ist.
17. Papier umfassend einen Füllstoff nach einem der Ansprüche 2, 4 bis 8 und 10 bis 16.
18. Papier nach Anspruch 16, dadurch gekennzeichnet, dass der Gesamtfüllstoffgehalt des Papiers von 5 bis 40 Gew.% beträgt, basierend auf dem
trockenen Papier.
19. Verfahren nach einem der Ansprüche 1 und 4 bis 16, dadurch gekennzeichnet, dass der Füllstoff in einer Menge von 5 bis 30 Gew.% hinzugefügt wird, basierend auf der
trockenen Faser.
1. Procédé pour la production de papier qui comprend le fait de fournir une suspension
aqueuse contenant des fibres cellulosiques, d'introduire dans la suspension une charge
comprenant, sous forme prémélangée, une argile et un dérivé de cellulose ayant un
degré de substitution de groupes ioniques totaux allant de 0,05 jusqu'à 0,65 où le
dérivé de cellulose contient des groupes cationiques, et de déshydrater la suspension
pour former une bande ou une feuille de papier.
2. Charge comprenant de l'argile et un dérivé de cellulose ayant un degré de substitution
de groupes ioniques totaux allant de 0,05 jusqu'à 0,65, où le dérivé de cellulose
contient des groupes cationiques.
3. Procédé de fabrication d'une charge qui comprend le fait de mélanger de l'argile avec
un dérivé de cellulose ayant un degré de substitution de groupes ioniques totaux allant
de 0,05 jusqu'à 0,65, où le dérivé de cellulose contient des groupes cationiques.
4. Procédé selon la revendication 1, charge selon la revendication 2, ou procédé selon
la revendication 3, caractérisé(e) en ce que le degré de substitution est d'au moins
0,10.
5. Procédé selon la revendication 1 ou 4, charge selon la revendication 2 ou 4, ou procédé
selon la revendication 3 ou 4, caractérisé(e) en ce que le degré de substitution varie
de 0,15 à 0,40.
6. Procédé selon l'une quelconque des revendications 1, 4 et 5, charge selon l'une quelconque
des revendications 2, 4 et 5, ou procédé selon l'une quelconque des revendications
3 à 5, caractérisé(e) en ce que le dérivé de cellulose est un éther de cellulose.
7. Procédé selon l'une quelconque des revendications 1 et 4 à 6, charge selon l'une quelconque
des revendications 2 et 4 à 6, ou procédé selon l'une quelconque des revendications
3 à 6, caractérisé(e) en ce que le dérivé de cellulose contient des groupes carboxyméthyle.
8. Procédé selon l'une quelconque des revendications 1 et 4 à 7, charge selon l'une quelconque
des revendications 2 et 4 à 7, ou procédé selon l'une quelconque des revendications
3 à 7, caractérisé(e) en ce que le dérivé de cellulose contient des groupes ammonium
quaternaire.
9. Procédé selon l'une quelconque des revendications 1 et 4 à 7, caractérisé en ce que le dérivé de cellulose est anionique.
10. Procédé selon l'une quelconque des revendications 1 et 4 à 8, charge selon l'une quelconque
des revendications 2 et 4 à 8, ou procédé selon l'une quelconque des revendications
3 à 7 et 9, caractérisé(e) en ce que le dérivé de cellulose est amphotère.
11. Procédé selon l'une quelconque des revendications 1 et 4 à 10, charge selon l'une
quelconque des revendications 2, 4 à 8 et 10, ou procédé selon l'une quelconque des
revendications 3 à 8 et 10, caractérisé(e) en ce que le dérivé de cellulose est au
moins partiellement hydrosoluble.
12. Procédé selon l'une quelconque des revendications 1 et 4 à 11, charge selon l'une
quelconque des revendications 2, 4 à 8, 10 et 11, ou procédé selon l'une quelconque
des revendications 3 à 8, 10 et 11, caractérisé(e) en ce que la charge a une teneur
en dérivé de cellulose allant de 0,3 à 10% en poids, par rapport au poids des matières
solides de la charge.
13. Procédé selon l'une quelconque des revendications 1 et 4 à 12, charge selon l'une
quelconque des revendications 2, 4 à 8 et 10 à 12, ou procédé selon l'une quelconque
des revendications 3 à 8 et 10 à 12, caractérisé(e) en ce que la charge a une teneur
en argile allant de 60 à 80% en poids, par rapport au poids des matières solides de
la charge.
14. Procédé selon l'une quelconque des revendications 1 et 4 à 13, charge selon l'une
quelconque des revendications 2, 4 à 8 et 10 à 13, ou procédé selon l'une quelconque
des revendications 3 à 8 et 10 à 13, caractérisé(e) en ce que l'argile est un kaolin.
15. Procédé selon l'une quelconque des revendications 1 et 4 à 14, charge selon l'une
quelconque des revendications 2, 4 à 8 et 10 à 14, ou procédé selon l'une quelconque
des revendications 3 à 8 et 10 à 14, caractérisé(e) en ce que l'argile est de l'argile
calcinée.
16. Procédé selon l'une quelconque des revendications 1 et 4 à 15, charge selon l'une
quelconque des revendications 2, 4 à 8 et 10 à 15, ou procédé selon l'une quelconque
des revendications 3 à 8 et 10 à 15, caractérisé(e) en ce que l'argile est du talc.
17. Papier comprenant une charge selon l'une quelconque des revendications 2, 4 à 8 et
10 à 16.
18. Papier selon la revendication 16, caractérisé en ce que la teneur en charge totale du papier varie de 5 à 40% en poids, par rapport au papier
sec.
19. Procédé selon l'une quelconque des revendications 1 et 4 à 16, caractérisé en ce que la charge est ajoutée en une quantité allant de 5 à 30% en poids, par rapport aux
fibres sèches.