Note: Descriptions are shown in the official language in which they were submitted.
CA 02929377 2016-05-02
WO 2015/100125 PCT/US2014/071139
METHOD FOR IMPROVING SIZING EFFICIENCY OF ASA EMULSION
EMULSIFIED BY A POLYMER EMULSIFIER
TECHNICAL FIELD
[0001] The present disclosure relates to a method for improving
sizing
efficiency of an ASA sizing agent in a paper-making process. In particular,
the
invention relates to a method for improving the sizing efficiency of a polymer
emulsifier emulsified ASA emulsion by treating paper-making filler particles
with a
hydroxyl-containing hydrocarbon natural polymer polysaccharide compound in the
sizing process of paper-making.
BACKGROUND OF THE INVENTION
[0002] Paper is a cellulose-containing fiber composite having a
typical polar,
strongly hydrophilic character, which is to say it can be easily wetted and
swelled by
aqueous system. When writing on and imprinting paper, and also when processing
paper, this results in excessive and uncontrolled penetration of water and
other
liquids (such as ink, printing inks) into the fibrous web. The resulting
problems
include weakening of the internal fiber bonding strength, worsening of the
mechanical properties, decrease in the dimensional stability, and very poor
writing
and imprinting ability.
[0003] In order to control the wetting and penetration behavior so
called
sizing agents are employed, which through partial hydrophobization counteract
the
aforementioned behavior. These auxiliary agents can be added both to the
aqueous
cellulose pulp (internal sizing) or be applied by way of a surface treatment
of the
previously formed paper web using an appropriate application system such as a
size
press, film press, coater and the like (surface sizing). Both methods are
employed
together for some types of paper.
[0004] In a neutral or slightly alkaline paper-making process,
neutral sizing
1
CA 02929377 2016-05-02
WO 2015/100125 PCT/US2014/071139
agents, such as typical neutral sizing agents including, e.g., alkyl ketene
dimer
(AKD) and alkenyl succinic anhydride (ASA) are used. In recent years, the use
of neutral sizing agents for the sizing of paper and board has become common
throughout the globe. Generally, the neutral sizing agent itself is a water
insoluble
oil. Therefore, it must be in an emulsion state before addition to the furnish
for
internal sizing. To get a stable emulsion of the neutral sizing agent, an
appropriate
emulsifier is of paramount importance. Cationic starch and synthetic
acrylamide
based polymers arc normally used as emulsifiers. Compared to cationic starch,
polymer emulsifiers are attracting more attention due to the fact that a large
amount
of cationic starch has to be used to achieve target sizing efficiency, whereas
a
relatively much smaller amount of synthetic polymer can be used to obtain a
similar
effect. Moreover, the use of a large amount of cationic starch greatly
increases the
chemical oxygen demand (COD) level in the water released from a paper mill,
which might cause serious environmental pollution. From environmental
protection
point of view, it is desirable to replace cationic starch with cationic
polymers.
[0005] In another aspect, due to cost reduction requirements, more
and more
fillers, such as CaCO3, TiO2 are being added to paper to decrease fiber
consumption.
However, such typically used fillers detrimentally affect the sizing of
alkaline paper.
With increasing ash content, that is, more fillers added, the neutral sizing
is
negatively impacted. More specifically, the effect of the neutral sizing when
using
polymeric emulsifiers is not ideal compared to cationic starch emulsifiers.
[0006] It has been reported in some literature that the sizing
efficiency can
be improved by surface treating the fillers, mainly focusing on
hydrophobization
modification and treatment techniques of fillers. U.S. Patent No. 5,411,639
discloses that a starch / fatty acid soap complex can be obtained by cooking
the
starch and then mixing the aqueous solution of the starch and the fatty acid
soap
(sodium or potassium salt of fatty acid) in certain conditions. When such
complex
is used to modify the filler, the sizing efficiency of the AKD can be
effectively
2
CA 02929377 2016-05-02
WO 2015/100125 PCT/US2014/071139
improved. U.S. Patent No. 5,527,430 also discloses a method for improving ASA
sizing efficiency wherein a polymer is used to surface modify the fillers so
that the
surface of the filler become hydrophobic. In both of the two methods, a fatty
acid
or a salt of the fatty acid is used, and the starch / fatty acid complex is
used in a large
amount, which causes a complex process. The use of large amounts of chemicals
for surface modifying calcium carbonate is not economically suitable for
practical
applications.
SUMMARY OF THE INVENTION
[0007] In view of the above defects in the prior art, the present
invention
solves the problems by providing a method for improving sizing efficiency of a
polymer emulsifier emulsified ASA emulsion, which can significantly improve
the
efficiency of the neutral sizing.
[0008] It has been found that the sizing efficiency of the polymer
emulsifier
emulsified ASA emulsion can be significantly improved by the use of a
hydroxyl-containing hydrocarbon natural polymer polysaccharide compound
modified paper-making filler particles as paper making fillers. Moreover, it
has
been surprisingly found that the above effect can be achieved by modifying an
paper-making filler particles with only very small amount of the
hydroxyl-containing hydrocarbon natural polymer polysaccharide compound.
[0009] That is, the invention provides a method for improving sizing
efficiency of a polymer emulsifier emulsified ASA emulsion in a paper-making
process, comprising: sizing a pulp slurry by using a polymer emulsifier
emulsified
ASA emulsion as a sizing agent, and, adding, as a paper-making filler, paper-
making
filler particles modified by a hydroxyl-containing hydrocarbon natural polymer
polysaccharide compound into the pulp slurry.
[0010] Furthermore, the invention provides a process for paper-making
comprising the steps of: adding paper-making filler particles modified by a
3
CA 02929377 2016-05-02
WO 2015/100125 PCT/US2014/071139
hydroxyl-containing hydrocarbon natural polymer polysaccharide into a pulp
slurry,
at the same time of or before or after adding a polymer emulsifier emulsified
ASA
emulsion into the pulp slurry.
[0011] According to the invention, the sizing efficiency of the ASA
sizing
can be significantly improved when a polymer emulsifier is used as an
emulsifier.
According to the invention, the sizing efficiency of the synthetic polymer-
emulsified
ASA emulsion is not less than the sizing efficiency of the ASA emulsion that
is
emulsified by a cooked cationic starch emulsifier.
DETAILED DESCRIPTION OF THE INVENTION
[0012] If it is not indicated otherwise, the scientific and technical
terminology in the specification has meanings the same as understood by one of
skill
in the art. If inconsistency occurs, the meanings used in the specification
should
prevail.
[0013] The invention provides a method for improving sizing
efficiency of a
polymer emulsifier emulsified ASA emulsion in a paper-making process,
comprising:
sizing a pulp slurry by using the polymer emulsifier emulsified ASA emulsion
as a sizing agent, and
adding paper-making filler particles which are modified by a
hydroxyl-containing hydrocarbon natural polymer polysaccharide compound as a
paper-making filler into the pulp slurry.
[0014] ASA
[0015] In the context, ASA refers to alkenyl succinic anhydrides,
which are
known as neutral sizing agent (see, e.g., U.S. Patent No. 3,102,064). ASA
sizing
agents are commercially available, such as N7540, N7542, and N7543 from Nalco
Co., A52300 from Kemi Co., etc. ASA is a water soluble oil, and its mixture
with
water is present in an emulsion. To get a stable ASA emulsion, an emulsifier
must
4
CA 02929377 2016-05-02
WO 2015/100125 PCT/US2014/071139
be used.
[0016] Polymer Emulsifier
[0017] As an emulsifier for emulsifying ASA emulsion, cationic starch
and
acrylamide -based synthetic polymer can be mentioned. In the context, polymer
emulsifiers can be a water-soluble acrylamide compound, which can be selected
from a group consisting of a copolymer of acrylamide and a cationic monomer as
well as a copolymer of glyoxal cross-linked acrylamide and a cationic monomer.
[0018] Herein, the cationic monomer can be selected from a group
consisting of dimethyldiallylammonium chloride, methylacrolyloxyethyltrimethyl
ammonium chloride, N,N,N-trimethy1-3-(2-methylallylamido)-1-propylammonium
chloride, N,N'- dimethylamino ethyl methacrylate, quatemary ammonium salt
cation
of N,N'-dimethylamino ethyl methacrylate, dimethylamino ethyl acrylate,
quatemary
ammonium salt of dimethylamino ethyl acrylate, diethylamino ethyl acrylate,
and
quatemary ammonium salt of diethylamino ethyl acrylate.
[0019] For example, the polymer emulsifier can be the copolymer of
acrylamide and a cationic monomer having a weight average molecular weight of
10,000 to 1,000,000 Dalton, in which the ratio of the cationic monomer unit to
the
acrylamide unit is between 1/99 and 20/80, for example, between 2/98 and
18/82, or
for example, between 5/95 and 15/85.
[0020] In the context, a "cationic monomer unit" refers to the moiety
of the
polymer that derives from a cationic monomer; a "acrylamide unit" refers to
the
moiety of the polymer that derives from acrylamide. A "glyoxal unit" refers to
the
moiety of the polymer that derives from glyoxal.
[0021] For example, the polymer emulsifier can be a copolymer of a
glyoxal
cross-linked acrylamide and a cationic monomer having a weight average
molecular
weight of 100,000-3,000,000 Dalton, in which the ratio of the acrylamide unit
to the
cationic monomer unit is between 5/95 and 95/5, the ratio of the glyoxal unit
to the
acrylamide unit is between 60/40 and 5/95, or for example, between 50/50 and
10/90,
CA 02929377 2016-05-02
WO 2015/100125 PCT/US2014/071139
or for example, between 45/55 and 10/90.
[0022] More particularly, the polymer emulsifier can be selected from
a
group consisting of a copolymer of methylacrolyloxyethyltrimethyl ammonium
chloride and acrylamide as well as glyoxal cross-linked dimethyldiallyl
ammonium
chloride acrylamide.
[0023] N7541 and N63007 From Nalco Co. and Bubond 650 from Buckman
Co. are examples of commercially available polymer emulsifiers that can be
used.
[0024] ASA emulsion emulsified by a polymer emulsifier
[0025] A polymer emulsifier emulsified ASA emulsion is known in the
art,
for example, by reference to U.S. Patent Nos. 4,657,946 and 6,491,790. A
polymer
emulsifier emulsified ASA emulsion can be prepared by, for example, mixing
e.g.,
0.01-10 parts by weight of a polymer emulsifier and 50-99.9 parts by weight of
water, and then adding 0.01-40 parts by weight of ASA, stirring in a high
shear
condition for 1-2 minutes. Herein, the "high shear condition" means that the
ASA is
dispersed into the water by a mechanical force so as to form an emulsion. The
high
shear condition can be achieved by known methods in the art. For example, it
can
be realized by a homogenizer or a turbo pump. In the polymer emulsifier
emulsified ASA emulsion, the content of ASA can be in an amount of 0.01-10
wt%.
The emulsified ASA particles can have a particle size of, e.g., 0.1-5 i.tm, or
for
example, 0.2-2 i.tm, or for example, 0.5-1.5 pm.
[0026] Paper-making filler particles modified by a hydroxyl-
containina
hydrocarbon natural polymer polysaccharide compound
[0027] Paper making filler particles modified by a hydroxyl-
containing
hydrocarbon natural polymer polysaccharide compound comprise: a core, which is
formed by an individual paper-making filler particle or an aggregate of
paper-making filler particles; and a covering layer, which is formed by the
hydroxyl-containing hydrocarbon natural polymer polysaccharide compound and
covers the surface of the core. Paper making filler particles modified by
6
CA 02929377 2016-05-02
WO 2015/100125 PCT/US2014/071139
hydroxyl-containing hydrocarbon natural polymer polysaccharides can be
composed
of only the above core and the above covering layer. A "covering layer formed
by a
hydroxyl-containing hydrocarbon natural polymer polysaccharide compound" is
intended to mean that the covering layer contains only the hydroxyl-containing
hydrocarbon natural polymer polysaccharides as a modifier for the paper-making
filler particles.
[0028] The hydroxyl-containing hydrocarbon natural polymer
polysaccharide comopund refers to polysaccharide macromolecule carbohydrates
formed by monosaccharide monomer (C6H1006) via glucosidic bond. The specific
examples can be selected from a group consisting of cellulose, cationic
cellulose,
chitosan , cationic chitosan, guar gum, cationic guar gum, cooked native
starch and
cooked cationic starch, or any combination thereof.
Specifically, the
hydroxyl-containing hydrocarbon natural polymer polysaccharide comopund can
also be a combination of any, such as two or three or more, selected from the
given
examples. For example, it can be the cooked starch in combination with one or
two or more selected from cellulose, chitosan, guar gum or their cationic
compound.
For example, it can be the cooked starch (cooked native starch and/or cooked
cationic starch in the specification). For example, it can be the cooked
native
starch.
[0029] "Paper-
making filler" or "filler for paper-making" is one class of
important raw materials for paper making, which can substitute a large amount
of
pulp fiber for paper making process. The use of the filler can substantially
decrease the cost of paper making, and improve the whiteness, opaqueness,
smoothness, glossiness of the final paper, the adaptability of the printing
and writing,
and/or the size stability, etc. In some conditions, it can also improve the
drainage
of the paper stock in wet end and decrease the cost of the paper-making. The
paper-making filler can be an inorganic filler or organic filler. The
inorganic filler
can be, for example, selected from kaolin, calcium carbonate, talc, titanium
dioxide,
7
CA 02929377 2016-05-02
WO 2015/100125 PCT/US2014/071139
aluminum hydroxide, calcium sulfate, and amorphous silicate, or any
combination
thereof. For example, the inorganic filler can be calcium carbonate in
combination
with one or two or more selected from kaolin, talc, titanium dioxide, aluminum
hydroxide, calcium sulfate, and amorphous silicate. The inorganic filler can
be, for
example, calcium carbonate. The calcium carbonate can be anionic calcium
carbonate, for example, anionic ground calcium carbonate or anionic
precipitate
calcium carbonate; or cationic calcium carbonate, for example, cationic
precipitate
calcium carbonate or cationic ground calcium carbonate.
[0030] The organic filler can be selected from a group consisting of
synthetic
polymer filler, starch-based filler, wood powder filler, or any combination
thereof.
The synthetic polymer filler can be, for example, 1,1-
dichloroethylene/acrylonitrile
copolymer, urea formaldehyde resin agglomerate filler and starch-based filler.
The
paper-making filler can be, for example, calcium carbonate in combination with
one
or two or more selected from a group consisting of kaolin, talc, titanium
dioxide,
aluminum hydroxide, calcium sulfate, amorphous silicate, polymer-based filler,
starch-based filler, and wood powder filler. The paper-making filler can be
either
surface unmodified or surface modified. The surface modification can be
carried
out by a conventional surface modifier in the art, such as unmodified starch,
cationic
starch.
[0031] "paper-making filler particles" refers to particles of paper-
making
filler which are not subject to an surface modification. The paper making
filler
particles can be primary particle (an individual paper-making filler
particle), or
secondary particle (aggregate of paper-making filler particles). There is no
special
limitation on the particle size of the paper-making filler particles, as long
as it does
not influence its use as paper making filler. The paper-making filler
particles can
have a particle size of such as 0.1-200 [tm, e.g., 2-100 [tm, e.g., 10-50 pm.
[0032] A "covering layer" refers to a layer that covers the surface
of the core.
The covering layer and the core can have a weight ratio of e.g., 0.1:100-
5:100, e.g.,
8
CA 02929377 2016-05-02
WO 2015/100125 PCT/US2014/071139
0.2:100-2:100, or e.g., 0.3:100-1.5:100.
[0033] The paper making filler particles modified by hydroxyl-
containing
hydrocarbon natural polymer polysaccharides can be produced by the following
methods. The production method includes:
[0034] 1. Preparation of a solution or a dispersion of the hydroxyl-
containing
hydrocarbon natural polymer polysaccharides. The solution or dispersion can
be,
e.g., aqueous solution or dispersion liquid. There is no special limitation to
the
content of the hydroxyl-containing hydrocarbon natural polymer polysaccharides
the
solution or dispersion, and it can be suitably selected according to the
practical
requirement, which can be 0.1-20 wt%, or e.g., 0.2-10 wt%, or e.g., 0.5-5 wt%.
[0035] 2. Preparation of a suspension of the paper-making filler
particles.
The suspension can be an aqueous suspension. There is no special limitation to
the
content of the paper-making filler particles in the suspension, which can be
suitably
selected according to the practical requirements. For example, the content of
the
paper-making filler particles in the suspension can be 1-60 wt%, or e.g., 5-30
wt%,
or e.g., 10-20 wt%.
[0036] 3. Mixing the solution or dispersion of the hydroxyl-
containing
hydrocarbon natural polymer polysaccharides and the suspension of the
paper-making filler particles so that the hydroxyl-containing hydrocarbon
natural
polymer polysaccharide compound covers the surface of the paper-making filler
particles. There is no special limitation to the mixing ratio of the solution
or
dispersion of the hydroxyl-containing hydrocarbon natural polymer
polysaccharides
to the suspension of the paper-making filler particles, which can be suitably
selected
according to the practical requirement. For example, relative to the 100 parts
by
weight of the paper-making filler particles in the suspension of the paper-
making
filler particles, the hydroxyl-containing hydrocarbon natural polymer
polysaccharides in the solution or dispersion of the hydroxyl-containing
hydrocarbon natural polymer polysaccharides can be added in an amount of 0.1-
20
9
CA 02929377 2016-05-02
WO 2015/100125 PCT/US2014/071139
parts by weight, or e.g., 0.2-10 parts by weight, or e.g., 0.5-5 parts by
weight.
During and/or after the mixing, the mixing can be facilitated by, e.g.,
stirring. The
obtained liquid can be used as paper-making filler directly, and the prepared
paper
making filler particles modified by the hydroxyl-containing hydrocarbon
natural
polymer polysaccharide compound can also be separated by means such as
filtration
and/or centrifugation. The weight ratio of the hydroxyl-containing hydrocarbon
natural polymer polysaccharide compound and the paper-making filler particles
in
the prepared paper making filler particles modified by the hydroxyl-containing
hydrocarbon natural polymer polysaccharide compound can be adjusted by
adjusting
the mixing ratio, mixing duration, stirring conditions,
filtration/centrifugation
conditions of the solution or dispersion of the hydroxyl-containing
hydrocarbon
natural polymer polysaccharide compound and the suspension of the paper-making
filler particles.
[0037] The weight ratio of the hydroxyl-containing hydrocarbon
natural
polymer polysaccharide compound to the paper-making filler particles in the
paper
making filler particles modified by the hydroxyl-containing hydrocarbon
natural
polymer polysaccharide compound can be determined, for example, by the
following method: the obtained paper making filler particles modified by the
hydroxyl-containing hydrocarbon natural polymer polysaccharide compound is
dried by, e.g., heating to remove the contained medium (e.g., water, organic
solvent),
and then weighed and indicated as Ml; the heat-dried paper making filler
particles
modified by the hydroxyl-containing hydrocarbon natural polymer polysaccharide
compound is immersed again with a medium (e.g., water, organic solvent) to
swell
the hydroxyl-containing hydrocarbon natural polymer polysaccharide compound
layer, and then the hydroxyl-containing hydrocarbon natural polymer
polysaccharide
compound layer is removed by a physical method (for example, polishing with
sandpaper), dried again, e.g. by heating the obtained paper-making filler
particles to
remove the attached medium, and then weighed again, indicated as M2; the
weight
CA 02929377 2016-05-02
WO 2015/100125 PCT/US2014/071139
ratio is M1-M2/ M2. For example, when the paper-making filler particles is
inflammable inorganic filler such as calcium carbonate, the weight ratio can
be
determined by the following method: separating the obtained paper making
filler
particles modified by the hydroxyl-containing hydrocarbon natural polymer
polysaccharide compound by filtration, such as drying at 120 C, to remove the
medium (e.g., water, organic solvent), taking a certain amount of the
completely
dried paper making filler particles modified by the hydroxyl-containing
hydrocarbon
natural polymer polysaccharide compound, weigh, indicated as Ml; heating in
the
air at 550 C for 2 hours, weigh again, indicated as M2; the weight ratio is
M1-M2/
M2.
[0038] Paper-Making Process
[0039] "Paper-making process" or "process for paper-making" is
intended to
mean a method of making paper products mainly comprising forming an aqueous
cellulosic papermaking furnish, draining the furnish to form a sheet and
drying the
sheet.
[0040] "Pulp slurry" or "pulp" is intended to mean a product obtained
from a
pulping process. "Pulping" involves a production process of dissociating the
plant
fiber raw materials by a chemical method or a mechanical method, or a
combination
of the both, to form a pulp slurry with an inherent color (unbleached pulp) or
further
to form a bleached pulp. The pulp can be any of known pulps, including but not
limited to, mechanical pulp, chemical pulp, chemical-mechanical pulp, and
recycled
waste pulp slurry, for example, a pulp containing mechanical pulp and / or
recycled
fiber.
[0041] The pulp is subject to pulping and additive adjustment,
producing a
fiber suspension which can be used in a hand sheet. Such fiber suspension is
called
as "paper stock", so as to be distinguished from the paper slurry which is not
subject
to the pulping and the additive adjustment.
[0042] "Wet paper sheet" refers to a product obtained after the pulp
stock
11
CA 02929377 2016-05-02
WO 2015/100125 PCT/US2014/071139
passed the headbox, the forming section and the press section to be formed and
partially drained, wherein the dryness of the wet paper sheet can be in a
range of
from 35% to 50%, for example. For the sake of clarity, the product which comes
from the forming section but is not subject to drainage in the press section
is called
as "wet paper web", which can have a dryness in a range of from 15% to 25%,
for
example.
[0043] "Paper sheet" refers to a product obtained after the wet paper
sheet is
dried in the dryer section. The dryness of the paper sheet can be in a range
of from
92% to 97%, for example.
[0044] In one aspect, the invention further provides a method for
paper
making, comprising the steps of:
(a) providing a pulp slurry;
(b) adding paper-making filler particles modified by a hydroxyl-containing
hydrocarbon natural polymer polysaccharide compound into the pulp slurry, at
the
same time of or before or after adding a polymer emulsifier emulsified ASA
emulsion into the pulp slurry, to obtain a paper stock;
(c) forming the obtained paper stock to obtain a wet paper web;
(d) pressing and draining the wet paper web obtained in the step (c) to obtain
a
wet paper sheet; and
(e) drying the wet paper sheet obtained in the step (d) to obtain a paper
sheet.
[0045] 1. The treatment before flowing onto the wire comprises:
[0046] (1) the preparation of paper stock: a paper slurry can be made
into a
paper stock, and the preparation of the paper stock comprises pulping and
additive
adjustment (adding additives such as sizings, fillers, pigments and aids). The
paper
slurry is first subject to pulping wherein the fiber of the paper slurry
undergoes
treatments such as necessary cutting, swelling and fine fibrosis, so as to
provide the
paper with physical properties and mechanical properties required by a certain
sort
of paper and meeting the requirements of a paper-making machine. In order to
12
CA 02929377 2016-05-02
WO 2015/100125 PCT/US2014/071139
render the paper sheet useful for writing and resistant to liquid
impregnation,
improve the paper color, white and tone, increase the transparency of the
paper and
increase the printing performance of the paper, etc., the paper slurry can
undergo
sizing, adding filler and staining. Furthermore, various chemical aids can be
added
to provide the paper with some special properties (for example, enhancing the
dry
strength, wet strength and eliminating bubbles). In this stage, a part or all
of the
paper-making filler particles modified by a hydroxyl-containing hydrocarbon
natural
polymer polysaccharide compound can be added into the paper slurry as a
filler.
Independently, at the same time of or before or after this, a part or all of
the polymer
emulsifier emulsified ASA emulsion can be added into the paper slurry as an
sizing
agent. As a filler, the paper slurry may be added with only the paper-making
filler
particles modified by a hydroxyl-containing hydrocarbon natural polymer
polysaccharide compound; and / or, as a sizing agent, the paper slurry may be
added
with only the polymer emulsifier emulsified ASA emulsion. It is apparent that
other fillers and / or sizing agents can be added into the paper slurry as
required.
[0047] (2) supplying the paper stock to the slurry supply system: the
paper
stock is supplied into the slurry supply system, undergoes treatments such as
storing,
screening, purifying, de-slagging, de-sanding, de-gasing, and discharges the
metal,
nonmetal impurities, fiber bundle, lump and air, etc., so as to avoid the
adverse
effects on the quality of paper and hinder the paper-making process. The
slurry
undergoes slurry proportion, dilution, concentration adjustment, dosage and
pressure
elimination, and then flowes into the head box and onto the wire for making
paper.
[0048] 2. The paper-making of paper comprises:
[0049] (1) stock flow approaching: the paper stock is delivered to
the
forming section (wire section) through the headbox. The headbox is useful in
dispersing the fiber homogeneously and flowing the slurry onto the wire
smoothly.
The additives for paper making, such as the dry strength aids for paper, the
wet
strength aids for paper, can be added in the process of stock flow
approaching. In
13
CA 02929377 2016-05-02
WO 2015/100125 PCT/US2014/071139
this stage, a part or all of the paper-making filler particles modified by a
hydroxyl-containing hydrocarbon natural polymer polysaccharide compound can be
added into the paper slurry as a filler. Independently, at the same time of or
before
or after this, a part or all of the polymer emulsifier emulsified ASA emulsion
can be
added into the paper slurry as an sizing agent. As a filler, the paper slurry
may be
added with only the paper-making filler particles modified by a hydroxyl-
containing
hydrocarbon natural polymer polysaccharide compound; and / or, as a sizing
agent,
the paper slurry may be added with only the polymer emulsifier emulsified ASA
emulsion. It is apparent that other fillers and / or sizing agents can be
added into
the paper slurry as required.
[0050] (2) forming: in the forming section, the paper stock delivered
by the
forming section is formed into a wet paper web by draining on the wire. The
forming section is also referred to as wire section. The dryness of the wet
paper
web can be in range of from 15% to 25%, for example.
[0051] The step (c) can be carried out by the step (1) or (2), but
not limited
to this.
[0052] (3) pressing and draining: in the pressing section, the wet
paper web
from the forming section is subject to a mechanical pressing to form a wet
paper
sheet. The dryness of the wet paper sheet can be in a range of from 35% to
50%,
for example.
[0053] The step (d) can be carried out by e.g., the step (3), but not
limited to
this.
[0054] (4) drying: in the dryer section, the wet paper sheet from the
pressing
section is dried with a dry cylinder to form a paper sheet. The dryness of the
paper
sheet can be in a range of from 92% to 97%, for example.
[0055] The step (e) can be carried out by e.g., the step (4), but not
limited to
this.
[0056] The amount of the paper making filler particles modified by
the
14
CA 02929377 2016-05-02
WO 2015/100125 PCT/US2014/071139
hydroxyl-containing hydrocarbon natural polymer polysaccharide compound added
into the paper slurry can be suitably selected by one skilled in the art
according to
the requirements, for example, can be 20-30 wt% of the final paper (when the
particles are added in several stages, the amount thereof refers to the total
amounts).
For example, relative to 100 parts by weight of over-dried pulp slurry, the
total
amount of the added paper making filler particles modified by the
hydroxyl-containing hydrocarbon natural polymer polysaccharide compound can
be,
e.g., 1-50 parts by weight, or e.g., 10-30 parts by weight, or e.g., 15-30
parts by
weight, or e.g., 20-30 parts by weight. The sizing in the above two stages is
called
as internal sizing, and this way of sizing is the way used in the paper making
process.
The amount of the added ASA emulsion emulsified by a polymer emulsifier can be
suitably selected by one skilled in the art according to the requirement, and
such
selection is a common skill of the skilled artisan (when the emulsion is added
in
several stages, the amount thereof refers to the total amounts). The ASA
emulsion
emulsified by a polymer emulsifier can be added, based on ASA, in an amount
of,
for example, 0.05-0.5 parts by weight, e.g., 0.05-0.1 parts by weight,
relative to 100
parts by weight of over-dried pulp slurry.
[0057] Moreover, the paper sheet can undergo, as required, finishing
procedures such as calendering, winding and cutting, paper-sorting or
rewinding,
packaging, etc., so as to produce the paper sheet in to a finished paper in
the form of
flat or roller. Additionally, in order to improve the quality of the paper
sheet,
surface sizing, coating and online soft calender or offline supercalender can
be
carried out in the dryer section.
[0058] In the paper-making process, the paper slurry provided by a
paper
stock preparation system is generally subject to a slurry supply system
(undergoing a
treatment before the paper stock flows onto the wire), the headbox and the
forming
section, the press section, dryer section, etc.
CA 02929377 2016-05-02
WO 2015/100125 PCT/US2014/071139
[0059] Examples
[0060] The invention is described in more detail by referring to the
following Examples and Comparative Examples, but not limited to these
Examples.
[0061] 1. Preparation of the cooked starch or other hydroxyl-
containing
hydrocarbon natural polymer polysaccharide compounds
[0062] As ahydroxyl-containing hydrocarbon natural polymer
polysaccharide compound, starch (either unmodified starch or cationic starch)
need
to be cooked for use. Starch paste was formed by cooking a certain amount of
the
starch in water.. The concentration of the starch paste was 2 wt%. For other
hydroxyl-containing hydrocarbon natural polymer polysaccharide compounds, a
solution or dispersion with a concentration of 1 wt% was formulated at room
temperature and stored for future use.
[0063] 2. Preparation of the hydroxyl-containing hydrocarbon natural
polymerpolysaccharide compound modified paper making filler particles by
covering the paper-making filler particles with cooked starch or other
hydroxyl-containing hydrocarbon natural polymer polysaccharide compounds
[0064] A suspension of calcium carbonate with a certain concentration
was
placed in a beaker and a certain amount of hydroxyl-containing hydrocarbon
natural
polymer polysaccharide compounds was added into calcium carbonate particles
under stirring for 10 minutes. After the addition of the hydroxyl-containing
hydrocarbon natural polymer polysaccharide compounds, the particle size of the
calcium carbonate particles increased significantly.
[0065] 3. Preparation of the ASA emulsion emulsified by a polymer
emulsifier
[0066] 0.01-10 g of N7541 or N63007 (both are Nalco products) was
mixed with 50-99.9g of water, and then added into 0.01-40g of ASA and stirred
for
1-2 minutes under a high shear condition, affording an ASA emulsion for
sizing.
16
CA 02929377 2016-05-02
WO 2015/100125 PCT/US2014/071139
[0067] 4. Sheeting procedure in laboratory scale and the water-
resistance test
of paper
[0068] The composition of the fiber slurry: 20% of needle bleached
kraft
pulp (NBKP), 20% of Leafwood bleached kraft pulp (LBKP), 20% of Bleached
chemi-thermomechanical pulp (BCTMP).
[0069] A certain amount of fiber slurry was mixed with a
corresponding
amount of pretreated filler. After mixing for 5 seconds, wet end starch was
added
followed by the addition of the polymer emulsified ASA emulsion 15 seconds
after
the mixing of fiber slurry and pretreated filler. Ten seconds after addition
of ASA
emulsion, the Nalco product N-61067 was added as retention aid and further
mixed
for 15 seconds. The stirring was stopped and the furnish mixture was
transferred to
a Rapid Kothen Sheet Former for sheeting. The formulation of the loaded slurry
for sheeting was 20-30 parts by weight of polysaccharide compound-treated
calcium
carbonate filler relative to 100 parts by weight of the loaded slurry. As a
control,
untreated calcium carbonate filler was used as filler as well and added into
the fiber
slurry for sheeting. A paper sheet with a diameter of 20 cm was formed after
being
drained though 100 mesh form line. Afterwards, the paper sheet was dried in
vacuum at 96 C for 8 minutes, and cured overnight at 24 C in a constant
temperature condition.
[0070] The water Resistance of the paper sample is tested by a
Hercules
Sizing Test, (HST). The HST method is an optical method measuring the
resistance
of paper to permeation of an aqueous penetrant and is a useful general-purpose
test
for degree of sizing. The penetration time of the test ink in the paper is
used to
evaluate the water Resistance of the paper. The ink used in the experiment
contains 1% of formic acid (see Tappi Official Method 530).
[0071] 5. Results of Experiments and Data Analysis
[0072] Example 1:
[0073] A solution of cationic chitosan (1% concentration) was added
into a
17
CA 02929377 2016-05-02
WO 2015/100125
PCT/US2014/071139
certain amount of anionic calcium carbonate suspension under stirring and
further
stirred for about 20 minutes. The average particle size of calcium carbonate
was
1.9 p.m before treatment, and increased to about 7-10 lam after treated by the
cationic chitosan solution. The weight ratio of the cationic chitosan and the
calcium carbonate in the particles was determined as about 0.3:100 to 1.5:100.
The
treated calcium carbonate suspension was added to a pulp slurry and used for
the
sheet according to the above step 4. The ASA emulsifier used for the sheet was
a
Nalco product, N7541, having a structure of a copolymer of
methylacrolyloxyethyl
trimethylammonium chloride and acrylamide containing 10 mol% cationic charge
(DMAEM*MCQ (Dimethylammoniumethylmethyacrylated methylchloride
quat)/AcAm(acrylamide)). Calcium carbonate accounted for about 27-30% of the
weigh of the final paper, that is, in the 100 parts by weight of pulp slurry
with filler,
about 27-30 parts by weight was calcium carbonate. The dosage of ASA used in
the handsheet making process, the amount of cationic chitosan used to treat
the
CaCO3 filler, the particle size of the filler before and after treatment, the
HST results
and the ash content of the final paper sheet are summarized in Table 1.
Table 1
Dosage of
CaCO3 Ash
ASA dosage (kg cationic chitosan
particle size HST(s) content
of
ASA/ton slurry) for treating
(P m) sheet
(%)
CaCO3 (kg/ton)
0.5 0 1.9 2.8 28.0
0.5 3 7.3 3.8 28.1
0.5 8 9.5 10.2 28.5
0.5 12 9.0 20.3 27.9
0.5 15 9.8 26.5 28.5
0.7 0 1.9 11.8 27.2
0.7 3 7.3 17.4 27.9
0.7 8 9.5 29.3 28.1
0.7 12 9.0 38.9 27.4
0.7 15 9.8 52 27.8
0.9 0 1.9 36.1 27.9
0.9 3 7.3 57.6 28.8
18
CA 02929377 2016-05-02
WO 2015/100125 PCT/US2014/071139
0.9 8 9.5 131.5 28.3
0.9 12 9.0 144.1 28.4
0.9 15 9.8 177.0 28.2
[0074] It can be seen from the above data that the pretreatment of
CaCO3
filler with cationic chitosan helps to improve the sizing efficiency of the
polymer
emulsified ASA emulsion. For example, in the case that calcium carbonate is
untreated, the filler is added in an amount of about 28-29 wt% and ASA is
added in a
dosage of 0.5kg/ton, the paper sample obtained from sheeting has a HST value
of
2.8 s; and the HST value increases to 26.5 s after the filler is treated with
cationic
chitosan in a dosage of 15kg/ton. In the case that calcium carbonate is
untreated,
the filler is added in an amount of about 28-29 wt% and ASA is added in a
dosage of
0.9kg/ton, the paper sample obtained from sheeting has a HST value of 36.1 s;
and
the HST value increases to 177.0 s after the filler is treated with cationic
chitosan in
a dosage of 15kg/ton.
[0075] Example 2:
[0076] A solution of guar gum (1% concentration, the cationic
substitution
degree is 0.04) was added into a certain amount of anionic calcium carbonate
suspension under stirring and further stirred for about 20 minutes. The
average
particle size of calcium carbonate was 1.9 pm before treatment, and increased
to
about 9-30 pm depending on the dosage of the guar gum. The weight ratio of the
cationic chitosan and the calcium carbonate in the particles was determined as
about
0.3:100 to 1.5:100. The treated calcium carbonate suspension was added to a
pulp
slurry and used for the sheet according to the above step 4. The ASA
emulsifier
used for the sheet was a Nalco product, N7541. Calcium carbonate accounted for
about 30% of the weigh of the final paper, that is, in the 100 parts by weight
of pulp
slurry with filler, about 30 parts by weight was calcium carbonate. The dosage
of
ASA used in the handsheet making process, the amount of cationic guar gum used
to
treat the CaCO3 filler, the particle size of the filler before and after
treatment, the
19
CA 02929377 2016-05-02
WO 2015/100125
PCT/US2014/071139
HST results and the ash content of the final paper sheet are summarized in
Table 2.
Table 2
Dosage of guar
ASA dosage
gum for treating CaCO3 particle Ash
content
(kg ASA/ton HST(s)
CaCO3 size ( m) of sheet
(%)
slurry)
(kg/ton)
0.6 0 2.6 4.5 28.0
0.6 3 8.8 11.1 27.8
0.6 8 25.7 32.3 28.5
0.6 12 32.7 32.6 29.1
0.6 15 21.6 32.7 28.1
0.8 0 2.6 12.1 27.6
0.8 3 8.8 31.2 28.1
0.8 8 25.7 81.3 28.6
0.8 12 32.7 80.2 28.7
0.8 15 21.6 87.6 28.3
1.0 0 2.6 15.5 28.4
1.0 3 8.8 45.0 29.1
1.0 8 25.7 122.3 28.2
1.0 12 32.7 136.5 28.1
1.0 15 21.6 141.3 28.6
[0077] It can be seen from the above data that the pretreatment of
calcium
carbonate with cationic guar gum helps to improve the sizing efficiency of the
polymer emulsified ASA emulsion. For example, in the case that calcium
carbonate is untreated, the filler is added in an amount of about 28-29 wt%
and ASA
is added in a dosage of 0.6kg/ton, the paper sample obtained from sheeting has
a
HST value of 4.5 s; and the HST value increases to 32.7 s after the filler is
treated
with cationic guar gum in a dosage of 15kg/ton. In the case that calcium
carbonate
is untreated, the filler is added in an amount of about 28-29 wt% and ASA is
added
in a dosage of 1.0kg/ton, the paper sample obtained from sheeting has a HST
value
of 15.5 s; and the HST value increases to 143.1 s after the filler is treated
with
cationic guar gum in a dosage of 15kg/ton.
CA 02929377 2016-05-02
WO 2015/100125 PCT/US2014/071139
[0078] Example 3:
[0079] Cooked cationic starch solution (2% concentration) was added
into a
certain amount of anionic calcium carbonate suspension under stirring and
further
stirred for about 20 minutes. The average particle size of calcium carbonate
was
1.9 lam before treatment, and increased to about 100 p.m after being treated
with the
starch solution. The weight ratio of the cationic chitosan and the calcium
carbonate
in the particles was determined as about 0.3:100 to 1.5:100. The treated
calcium
carbonate suspension was added to a pulp slurry for sheeting. Calcium
carbonate
accounted for about 30% of the weigh of the final paper, that is, in the 100
parts by
weight of pulp slurry with filler, about 30 parts by weight was calcium
carbonate.
The composition of the fiber pulp slurry was: 20%NBKP+60%LBKP+ 20%BCTMP,
and the basis weight of the paper was 100 g/m2. The polymer emulsifier used in
the experiment was a Nalco product, N63007. In Table 3, the test data for
water
resistance are shown.
Table 3
Dosage of cooked
ASA dosage CaCO3
cationic starch for Ash content
(kg ASA/ton particle size HST(s)
treating CaCO3 of Sheet
slurry) (Pm)
(kg/ton)
0.5 0 1.9 6.2 29.4
0.5 3 102.9 8.2 29.1
0.5 8 107.2 41.8 29.2
0.5 12 102.6 61.7 29.5
0.5 15 105.0 110.2 28.8
0.7 0 1.9 31.2 29.1
0.7 3 102.9 56.3 29.2
0.7 8 107.2 108.9 29.3
0.7 12 102.6 175.7 29.2
0.7 15 105.0 242.8 29.6
0.9 0 1.9 68.3 29.7
0.9 3 102.9 127.6 29.6
0.9 8 107.2 258 29.7
0.9 12 102.6 308.7 29.2
21
CA 02929377 2016-05-02
WO 2015/100125 PCT/US2014/071139
0.9 15 105.0 1 395.6 1 29.5
[0080] It can be seen from the above data that the pretreatment of
CaCO3
filler with cationic cooked starch helps to improve the sizing efficiency of
the
polymer emulsified ASA emulsion. For example, in the case that calcium
carbonate is untreated, the filler is added in an amount of about 28-29 wt%
and ASA
is added in a dosage of 0.5 kg/ton, the paper sample obtained from sheeting
has a
HST value of 6.2 s; and the HST value increases to 110.2 s after the filler is
treated
with cooked cationic starch a dosage of 15kg/ton. In the case that calcium
carbonate is untreated, the filler is added in an amount of about 28-29 wt%
and ASA
is added in a dosage of 0.9 kg/ton, the paper sample obtained from sheeting
has a
HST value of 68.3 s; and the HST value increases to 395.6s after the filler is
treated
with the cooked cationic starch in a dosage of 15kg/ton.
[0081] Example 4:
[0082] A solution of cooked unmodified starch (2% concentration) was
added into a certain amount of anionic calcium carbonate suspension under
stirring
and further stirred for about 20 minutes.The average particle size of calcium
carbonate was 2 pm before treatment, and increased to about 17-50 m depending
on
the dosage of the starch in the treatment solution. The weight ratio of the
cationic
chitosan and the calcium carbonate in the particles was determined as about
0.3:100
to 1.5:100. The treated calcium carbonate suspension was added to a pulp
slurry
for sheeting. Calcium carbonate accounted for about 28-30% of the weigh of the
final paper, that is, in the 100 parts by weight of pulp slurry with filler,
about 28-30
parts by weight was calcium carbonate. The composition of the fiber pulp
slurry was:
20%NBKP+60%LBKP+20%BCTMP, and the basis weight of the paper was
100g/m2. The polymer emulsifier used in the experiment was a Nalco product,
N63007. In Table 4, the test data for water resistance are shown.
Table 4
22
CA 02929377 2016-05-02
WO 2015/100125 PCT/US2014/071139
Dosage of cooked Ash
ASA dosage CaCO3
unmodified starch content
(kg ASA/ ton particle size HST(s)
for treating CaCO3 of sheet
slurry) (P m)
(kg/ton) (%)
0.5 0 1.9 2.6 29.9
0.5 3 17.3 17.3 30.5
0.5 8 48.1 67.6 29.8
0.5 12 43.7 86.4 29.6
0.5 15 37.8 122.1 29.5
0.7 0 1.9 8.3 30.2
0.7 3 17.3 64.8 28.6
0.7 8 48.1 111.9 28.2
0.7 12 43.7 144.9 29.1
0.7 15 37.8 172.4 27.9
0.9 0 1.9 16.3 30.3
0.9 3 17.3 87.8 28.1
0.9 8 48.1 155.3 27.9
0.9 12 43.7 215.8 28.6
0.9 15 37.8 240.5 27.5
[0083] It can be seen from the above data that the pretreatment of
calcium
carbonate with the cooked unmodified starch helps to improve the sizing
efficiency
of the polymer emulsified ASA emulsion. For example, in the case that calcium
carbonate is untreated, the filler is added in an amount of about 28-29 wt%
and ASA
is added in a dosage of 0.5 kg/ton, the paper sample obtained from sheeting
has a
HST value of 2.6s; and the HST value increases to 122.1s after the filler is
treated
with cooked cationic starch a dosage of 15kg/ton. In the case that calcium
carbonate is untreated, the filler is added in an amount of about 28-29 wt%
and ASA
is added in a dosage of 0.9 kg/ton, the paper sample obtained from sheeting
has a
HST value of 16.3s; and the HST value increases to240.5 s after the filler is
treated
with the cooked cationic starch in a dosage of 15kg/ton.
[0084] Example 5: Compared with the case wherein the starch is used
as
emulsifier
[0085] Cationic starch is one of the most commonly used efficient
23
CA 02929377 2016-05-02
WO 2015/100125 PCT/US2014/071139
emulsifiers used in the ASA sizing. The purpose of the example is to compare
the
sizing efficiency of 7541 as emulsifier when the filler is pretreated with
cooked
starch with the sizing efficiency of cationic starch directly used as
emulsifier. In
the experiments, the calcium carbonate filler was pretreated with the cooked
starch
when 7541 was used as emulsifier. The dosage of the cooked unmodified starch
used to prtreat the filler was 10kg cooked starch per ton of the filler. U.S.
Patent
No. 5,411,639 discloses that starch and sodium stearylcarboxylate are used to
treat
calcium carbonate filler so as to improve the sizing efficiency. In the
present
experiment, the influence of calcium carbonate on ASA sizing efficiency were
compared, wherein calcium carbonate is treated by a complex formed by the
addition of sodium stearylcarboxylate into the cooked starch. It can be found
from
the experiment that cooked starch worked more efficiently to improve the
polymer
emulsified ASA sizing efficiency than cook starch-sodium stearylcarboxylate
complex by the filler treatement approach. N7541 worked more efficiently as an
emulsifier when the filler was pretreated as compared to cooked starch where
the
filler was not pretreated.
Table 5: Comparison of the ASA sizing efficiency between N7541 as emulsifier
when the filler was pretreated with the cooked starch, and cationic starch as
emulsifier
ASA dosage
Emulsifier CaCO3 Pretreatment HST(s)
(kg/T)
kg/T
0.5 24.5
N7541 Cooked Unmodified Starch
10 kg/T
0.7 59.1
N7541 Cooked Unmodified Starch
10 kg/T
0.9 123.3
N7541 Cooked Unmodified Starch
Cooked
Untreated 0.5 4.8
Starch
Cooked
Untreated 0.7 38.1
Starch
24
CA 02929377 2016-05-02
WO 2015/100125 PCT/US2014/071139
Cooked
Untreated 0.9 99.1
Starch
Cooked Unmodified Starch
N7541 + 0.5 6.35
sodium stearylcarboxylatea
Cooked Unmodified Starch
N7541 + 0.7 19.4
sodium stearylcarboxylatea
Cooked Unmodified Starch
N7541 + 0.9 45.4
sodium stearylcarboxylatea
a: The cooked starch used to pretreat the calcium carbonate filler contains 5
wt% of
sodium stearylcarboxylate with a dosage of 10kg/ton calcium carbonate. The
calcium carbonate was added in an amount of 30% based on the weight of the
final
paper.
[0086] Example 6:Influence ofCaCO3 in different contents
[0087] In the example, the influences of the starch-treated filler in
different
filler dosages on the sizing efficiency of the polymer emulsifier were
compared,
wherein the used starch was the cooked non-cationized unmodified starch. The
composition of the used fiber pulp slurry was:
20%NBKP+60%LBKP+20%BCTMP, the basis weight of the paper was 100g/m2,
and the polymer emulsifier used in the experiment was a Nalco product, N7541.
Table 6: Influence of N7541 as emulsifier in different filler dosages on the
sizing
efficiency of the polymer emulsifier-emulsified ASA emulsion
Calcium Carbonate
Pretreatment Dosage of the
Emulsifier ASA dosage (kg Cooked added calcium HST(s)
(kg/T)
Unmodified Starch/t carbonate (%)
Calcium Carbonate)
N7541 0.9 5 10 345.5
N7541 0.9 5 15 284.4
N7541 0.9 5 20 196.1
N7541 0.9 5 30 73.1
CA 02929377 2016-05-02
WO 2015/100125 PCT/US2014/071139
N7541 0.9 10 10 365.6
N7541 0.9 10 15 306.3
N7541 0.9 10 20 259.5
N7541 0.9 10 30 114.3
N7541 0.9 15 10 514.3
N7541 0.9 15 15 393.9
N7541 0.9 15 20 319.8
N7541 0.9 15 30 173.2
[0088] It can be seen from Table 6 that the sizing efficiency of ASA
decreases with the increase of the amount of the added fillers while the
sizing
efficiency of ASA is improved when the amount of the starch used for treating
calcium carbonate is increased.
26
