Note: Descriptions are shown in the official language in which they were submitted.
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REDUCED SHEAR CELLULOSE REACTIVE SIZING AGENT
FOR WET END APPLICATIONS
BACKGROUND
It is well known that the property of sizing, as applied to paper, refers
to a fibrous substrate's ability to resist wetting or penetration of a liquid
into a
paper sheet. Aqueous dispersions of alkenylsuccinic anhydride cellulose-
reactive sizing agent have been widely used in the paper and board making
industry for many years, for sizing a wide variety of grades which include
printing and writing grades and bleached and unbleached board grades.
Cellulose-reactive alkenylsuccinic anhydride imparts hydrophobic properties
to, the paper and board products.
Chemicals used to achieve sizing properties are known as either
internal sizes or surface sizes. Internal sizes can be either rosin-based or
synthetic sizes such as alkenylsuccinic anhydride, or other materials.
Internal
sizes are added to the paper pulp prior to sheet formation. Surface sizes are
sizing agents that are added after the paper sheet has formed, most generally
at the size press, although spraying applications may also be used.
Alkenylsuccinic anhydride sizing agent is ordinarily applied by
dispersing it in a cationic or amphoteric hydrophilic substance such as a
starch or a polymer. The starch or polymer-dispersed alkenylsuccinic
anhydride sizing emulsion is added to the pulp slurry before the formation of
a
paper web. This type of addition of alkenylsuccinic anhydride sizing
emulsions to the papermaking system is commonly called wet-end addition or
internal addition of alkenyisuccinic anhydride.
Application of wet end applied cellulose reactive sizing agents such
as alkenyl succinic anhydride using traditional emulsification methods has
the following disadvantages: ASA emulsification in cationic starch needs a
high starch/size ratio for emulsification. Also, in addition to the foregoing
problem, the starch needs to be an high quality starch suitable for
producing a stable, high quality ASA emulsion. ASA emulsification in
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cationic polymer or starch-grafted polymer also uses a lower polymer/size
ratio than for starch, but a polymer that provides a stable, high quality ASA
emulsion is needed for emulsification. Also the traditional emulsification of
ASA in starch or polymer solution requires high shear conditions.
It would be desirable to develop an improved method of sizing paper at
the wet end that will use a simpler and less expensive, low shear equipment
for the ASA emulsification.
SUMMARY
The invention relates to method for sizing a paper product that involves
the steps of: (a) providing a paper stock system; (b) forming, in the absence
of
high shearing forces, an aqueous sizing emulsion comprising an alkenyl
succinic anhydride component; (c) submitting the emulsion formed from step
b to a post-dilution step in the presence of a cationic component under
conditions, in the absence of high shearing forces, that produce a post-
diluted
emulsion having improved sizing efficacy; (d) adding the post-diluted emulsion
to the paper stock; and (e) forming a paper web.
In one embodiment, the invention relates to a paper made by the
above-mentioned process.
In one embodiment, the invention relates to a method for sizing a paper
product comprising:
(a) providing a paper stock system;
(b) forming, in the absence of high shearing forces, an aqueous
sizing
emulsion comprising an alkenylsuccinic anhydride component;
wherein the emulsion is made in the presence of a cationic component
under conditions, in the absence of high shearing forces, that produce an
emulsion having improved sizing efficacy;
(d) adding the emulsion to the paper stock; and
(e) forming a paper web.
These and other features, aspects, and advantages of the present
invention will become better understood with reference to the following
description and appended claims.
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DESCRIPTION
Other than in operating examples or where otherwise indicated, all
numbers or expressions referring to quantities of ingredients, reaction
conditions, and the like, used in the specification and claims are to be
understood as modified in all instances by the term "about." Various numerical
ranges are disclosed in this patent application. Because these ranges are
continuous, they include every value between the minimum and maximum
values. Unless expressly indicated otherwise, the various numerical ranges
specified in this application are approximations.
The emulsion prepared prior to the post-dilution step includes an
alkenyisuccinic anhydride-containing emulsion, which when subjected to a
post-dilution step, improves sizing efficacy as compared to an emulsion that
is
not subjected to a post-dilution step. The emulsion, for instance, can include
an alkenylsuccinic anhydride component containing alkenylsuccinic anhydride
particles suspended in a starch component containing emulsifying starch
selected from the group consisting of non-ionic starches, anionic starches,
cationic starches and mixtures thereof. Starches that are used for the
emulsification can be based on corn, potato, wheat, tapioca, or sorghum, and
they could be modified through the use of enzymes, high temperature or
chemical/thermal converting techniques.
Alternatively, the emulsion can include an alkenyisuccinic anhydride
component containing alkenyisuccinic anhydride particles suspended in an
aqueous polymer solution selected from the group of cationic polymers,
nonionic polymers, anionic polymers, vinyl addition polymers, condensation
polymers, and mixtures thereof. In one version of the invention, the invention
includes an alkenylsuccinic anhydride component containing (i)
alkenylsuccinic anhydride particles and (ii) surfactant component; suspended
in water.
The emulsion of step (b) can be made by any suitable method.
Generally, the emulsion is made with an emulsifying agent, e.g., a surfactant.
Cationic polymer or cationic starch may be present, but they are not required.
The weight ratio of the alkenylsuccinic anhydride to polymer or starch solids
generally ranges from 1 to 0.02 to 1:1, or from 1 to 0.05 to 1 to 0.5, or from
1
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to 0.1 to.1 to 0.2.In one embodiment, for instance, the emulsion in step (b)
can be made by emulsifying an alkenyisuccinic anhydride component
containing (i) alkenyisuccinic anhydride and (ii) a surfactant component, with
water; and thereby forming an emulsion having an alkenyisuccinic anhydride
component containing (i) alkenylsuccinic anhydride particles and (ii) a
surfactant component; suspended in water. Alternatively, the emulsion in step
(b) can be made by emulsifying an alkenylsuccinic anhydride component,
optionally containing a surfactant, with an aqueous polymer solution, and
thereby forming the emulsion. The sizing emulsion can be formed with a
polyoxyalkylene alkyl ether or one surfactant selected from the group
consisting of sulfosuccinates, alkyl and aryl amides and primary, secondary
and tertiary amines and their corresponding quaternary salts, fatty acids,
ethoxylated fatty acids, fatty alcohols, ethoxylated fatty alcohols, fatty
esters,
ethoxylated fatty esters, ethoxylated triglycerides, certain ethoxylated
lanolin,
sulfonated amines, sulfonated amides, ethoxylated polymers, propoxylated
polymers, ethoxylated/ propoxylated copolymers, polyethylene glycols,
phosphate esters, phosphonated fatty acid ethoxylates, phosphonated fatty
alcohol ethoxylates, alkyl sulfonates, aryl sulfonates, alkyl sulfates, aryl
sulfates, and combinations thereof.
The polymer used to emulsify the alkenyisuccinic anhydride can be
any polymer, which when used in accordance with the invention, can produce
an emulsion in accordance with the invention. Examples of suitable polymers
used in the emulsion of this sizing composition include polymeric stabilizers
that include vinyl addition and condensation polymers having anionic,
cationic, non-ionic and amphoteric charge characteristics with a charge
substitution range varying from 0 to about 90%, and more preferably from 0 to
about 10%. Further, the molecular weight of aforementioned synthetic
polymeric stabilizer generally falls within the value ranging from about
10,000
to about 10 million daltons, or from about 100,000 to about two million or
from
about 200,00 to about 1 million daltons. All molecular weights mentioned
herein are weight average.
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Generally, suitable water-soluble polymers of this instant invention are
cationic vinyl addition polymers, anionic vinyl addition polymers, neutral
polymers, ampholytic polymers and condensation polymers.
Examples of suitable polymers include, water-soluble polymers having
molecular weights ranging from 10,000 daltons to 3,000,000 daltons. The
substantially water-soluble polymers to be used in this invention are
comprised of but not limited to homopolymers and copolymers, and
combinations thereof leading to terpolymers, and tetrapolymers comprised of
the following monomers: acrylamide, diallyldimethylammonium chloride,
dimethylaminoethylacrylate, dimethylaminoethyfacrylate quaternaries,
diethylaminoethyl acrylate, diethylaminoethylacrylate quaternaries,
dimethylaminoethylmethacrylate, dimethylaminoethylmethacrylate
quaternaries, dimethylaminoethylmethacrylate and its quaternaries,
methacrylamidopropyltrimethyl ammonium chloride, acrylic acid. Suitable
polymers also include polymers and copolymers of acrylamide that have been
subjected to the "Mannich" reaction. Also, in one embodiment, the
corresponding Mannich quaternaries are possible water-soluble polymers.
Examples of other water-soluble polymers include copolymers comprised of
substantially water-soluble and water dispersible styrene-alkylacrylates,
styrene alkylacrylics, styrene maleic acid, styrene-maleic acid amide, styrene
maleic acid esters, styrene maleic acid amide ester, and their corresponding
salts. In another embodiment, suitable polymers include aqueous dispersions
containing combinations of the reaction products of the above monomers,
polyurethane dispersions with polyvinyl alcohol, poly vinylalcohol-
vinylamine),
their corresponding acetates or formamates or partially hydrolyzed polymers,
or polyvinylamine.
Examples include copolymers of N,N-dialkylamino-alkyl(meth)
acrylates and/or amides and/or alkyl(meth)acrylates , styrene, isobutylene,
diisobutylene, vinyl acetate and/or acrylonitrile. Examples include
condensation polymers of trimethlyene diamine and 1,2-dichloroethane or 1,3
dichloropropane; adipic acid with diethylenetriamine, tetraethylenepentamine
or similar polyalkylene; polyamides; subsequent reaction products with
epichlorohydrin; dimethylamine-epichlorohydrin; ethylenediamine
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polyacrylamide. Examples include polyvinyl pyridine, poly-N-methyl pyridinium
chloride; poly-p-chlorostyrene quaternized with trialkylamine. Examples of
such suitable polymers are described in U.S. Pat. Nos. 4,657,946, 4,784,727,
3,445,330, 6,346,554, incorporated herein by reference in their entirety.
Natural polymers, gums, and their extracts included in the
embodiments of the invention may be taken from the following list: guar,
acacia, agar, algin, carrageenan, cellulose and its derivatives, chitin,
chitosan,
damar, dextran, dextrin, ethylcellulose, gelatin, gellan, jalap, karaya, kelp,
locust bean, methlycellulose, olibanum, pectin, rhamsan, sandarac,
tragacanth, welan, and xanthan. This includes the salts and derivatives of the
natural polymers. The polymers may be in their natural state or derivatized
thereafter to form salts or other derivatives (e.g. hydroxyethylated).The
products may be anionic, cationic, amphoteric, or neutral.
The emulsion may be made in the absence of high shearing forces
(low shear conditions), e.g., those shearing conditions are created by a
device selected from the group of centrifugal pumps, static in-line mixers,
peristaltic pumps, and combinations thereof.
The alkenylsuccinic anhydride component generally includes
alkenyisuccinic anhydride compounds composed of mono unsaturated
hydrocarbon chains containing pendant succinic anhydride groups. The
alkenylsuccinic anhydride compounds are generally liquid and may be
derived from maleic anhydride and suitable olefins. The alkenylsuccinic
anhydride compounds may be solid.
Generally speaking, the alkenylsuccinic anhydride compounds may be
made by reacting an isomerized C14 - C20 mono olefin, preferably an excess
of an internal olefin, with maleic anhydride, at a temperature and for a time
sufficient to form the alkenylsuccinic anhydride compound.
If the olefin to be employed in the preparation of the alkenylsuccinic
anhydride compounds is not an internal olefin as is the case for example, with
a-olefins, it may be preferable to first isomerize the olefins to provide
internal
olefins. The olefins that may be used in the preparation of the
alkenylsuccinic
anhydride compounds may be linear or branched. Preferably, the olefins may
contain at least about 14 carbon atoms. Typical structures of alkenyisuccinic
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anhydride compounds are disclosed, for example, in U.S. Pat. No. 4,040,900,
incorporated herein by reference in its entirety. Alkenyisuccinic anhydride
compounds and methods for their preparation are described, for example, in
C. E. Farley and R. B. Wasser, "The Sizing of Paper, Second Edition," edited
by W. F. Reynolds, TAPPI Press, 1989, pages 51-62, the disclosures of
which are hereby incorporated herein by reference in its entirety.
The alkenylsuccinic anhydride component may contain some
hydrolyzed alkenylsuccinic anhydride. The amount of hydrolyzed
alkenylsuccinic anhydride may range from about 1 to about 30 wt.%, based
on the total weight of the alkenylsuccinic anhydride component.
The alkenylsuccinic anhydride component can include:
a. from 80 to 97 parts of substituted cyclic dicarboxylic acid
anhydride corresponding to the formula
0
~C\
O\ /R-R'
C
I I
O
(A)
wherein R represents a dimethylene or trimethylene radical and
wherein R' is a hydrophobic group containing more than 5 carbon atoms
which may be selected from the class consisting of alkyl, alkenyl, aralkyl, or
aralkenyl groups;
Rx
1
H iH2
aC-C-CH-CH=CH-Ry O\ I
C-CH2
(B)
O
wherein RX is an alkyl radical containing at least 5 carbon atoms and
Ry is an alkyl radical containing at least 5 carbon atoms, and Rx and Ry are
interchangeable;
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(C)
H
OsC I -CH2 I -CH2-Rx
~C-CH2 CH
O Ry wherein Rx is an alkyl radical containing at least 5 carbon atoms and Ry
is an alkyl radical containing at least 5 carbon atoms and RX and Ry are
interchangeable; and
b. from 3 to 20 parts of a polyoxyalkylene alkyl or polyoxyalkylene
alkyl-aryl ether or the corresponding mono- or diester selected from the group
consisting of:
i)
O O
c%xH2x+1-C-O-[(CH2)i-CH2-CH2-O]m C-CnH2n+1
ii) 0
HO-[(CH2)1-CH2-CH2-O] nr-C11
-LnH2n+i
iii)
HO-[(CH2)i-CH2-CH2-O] m-R- CnH2n+1
iv)
HO-[(CH2)i-CH2-CH2-O]m--CnH2n+i
wherein x and n are integers in the range of 8 to 20; R is an aryl
radical; m is an integer in the range of 5 to 20; and i is 0, 1, or 2.
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The alkenylsuccinic anhydride component is generally present in the
emulsion in an amount that is at least about 0.01 wt.%, or from about 0.1 to
about 20 wt.%, or from about 0.3 wt.% to about 15 wt. %, based on the total
weight of the emulsion. The emulsion generally contains alkenylsuccinic
anhydride particles ranging from 0.5 microns to less than 3 microns.
When a surfactant is used to make the emulsion, the surfactant
component includes surfactants, which when used to make an emulsion in
accordance with the invention, produces an emulsion that minimizes
coalescing and imparts useful sizing properties to a fibrous substrate after
the
emulsion contacts the fibrous substrate. The surfactant component functions
as an emulsifying agent when the emulsion is made. The surfactant
component facilitates the emulsification of the alkenyisuccinic anhydride with
the water component when the emulsion is made. Generally, the surfactants
are anionic or nonionic or can be cationic and can have a wide range of HLB
values.
Examples of suitable surfactants include but are not limited to alkyl and
aryl primary, secondary and tertiary amines and their corresponding
quaternary salts, sulfosuccinates, fatty acids, ethoxylated fatty acids, fatty
alcohols, ethoxylated fatty alcohols, fatty esters, ethoxylated fatty esters,
ethoxylated triglycerides, sulfonated amides, sulfonated amines, ethoxylated
polymers, propoxylated polymers or ethoxylated/ propoxylated copolymers,
polyethylene glycols, phosphate esters, phosphonated fatty acid ethoxylates,
phosphonated fatty alcohol ethoxylates, and alkyl and aryl sulfonates and
sulfates. Examples of preferred suitable surfactants include but are not
limited
to amides; ethoxylated polymers, propoxylated polymers or
ethoxylated/propoxylated copolymers; fatty alcohols, ethoxylated fatty
alcohols, fatty esters, carboxylated alcohol or alkylphenol ethoxylates;
carboxylic acids; fatty acids; diphenyl sulfonate derivatives; ethoxylated
alcohols; ethoxylated fatty alcohols; ethoxylated alkylphenols; ethoxylated
amines; ethoxylated amides; ethoxylated aryl phenols; ethoxylated fatty acids;
ethoxylated triglycerides; ethoxylated fatty esters; ethoxylated glycol
esters;
polyethylene glycols; fatty acid esters; glycerol esters; glycol esters;
certain
lanolin-based derivatives; monoglycerides, diglycerides and derivatives;
olefin
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sulfonates; phosphate esters; phosphorus organic derivatives; phosphonated
fatty acid ethoxylates, phosphonated fatty alcohol ethoxylates; polyethylene
glycols; polymeric polysaccharides; propoxylated and ethoxylated fatty acids;
alkyl and aryl sulfates and sulfonates; ethoxylated alkylphenols;
sulfosuccinamates; sulfosuccinates.
In one embodiment, the surfactant component includes an amine
selected from the group consisting of trialkyl amine of the formula (I):
R,
I
R2 I
R3
dimethyl sulfate quaternary salt of trialkyl amine of the formula (I), benzyl
chloride quaternary salt of trialkyl amine of the formula (I), and diethyl
sulfate
quaternary salt of trialkyl amine of the formula (I), in which R, is methyl or
ethyl, R2 is methyl or ethyl, and R3 is alkyl having 14 to 24 carbon atoms. In
another embodiment, the surfactant excludes this amine.
The surfactant levels can range from about 0.1 weight % up to about
weight % based on the alkenylsuccinic anhydride component.
It has been discovered that the following examples do not provide
suitable results (produce paper products with useless sizing properties) under
certain conditions: sorbitan monolaurate (Arlacel 20), ethoxylated sorbitan
20 trioleate (Tween 85), propoxylated lanolin (Solulan PB-5), ethoxylated
lanolin
(Laneto 100), sorbitan trioleate (Span 85), isostearic alkanolamide (Monamid
150-IS), hydroxylated milk glycerides (Cremophor HMG), bis(tridecyl) ester of
sodium sulfosuccinic acid (AEROSOL TR-70).
The post-dilution step generally involves mixing the emulsion with a
cationic component at autogenous conditions. The cationic component can be
selected from the group consisting of cationic starches, cationic polymers,
cationic starch-grafted polymers, and mixtures thereof. Also, the cationic
component can be selected from the group consisting of cationic vinyl addition
polymers, cationic condensation polymers, and combinations thereof.
Starches that are used for the post-dilutation step can be based on corn,
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potato, wheat, tapioca, or sorghum, and they could be modified through the
use of enzymes, high temperature or chemical/thermal converting techniques.
The starches that are used for the post-dilution have to be cationic.
The ratio of the cationic component solids to the alkenyisuccinic
anhydride in the post-dilution step should range from 0.1:1 to 4:1, but in
some
cases could be as high as 50:1. This ratio will depend on the requirements for
a specific paper production application.
The temperature at which the process of the invention can be carried
out is generally less than 50 C. The pH at which the process of the invention
is practiced varies, depending on the application. The pH, for instance, can
range from 4 to 8 or from 6 to 8. The post-dilution step is generally carried
out
under low shear conditions e.g., those shearing conditions are created by a
device such as selected from the group of centrifugal pumps static in-line
mixers, peristatic pumps, magnetic stirring bar in a beaker, overhead stirrer,
and combinations thereof. Although the post dilution step is typically carried
out, in one embodiment, if alkenyl succinic anhydride is emulsified in a
cationic component than the post-dilution with a second cationic component is
optional.
The duration of the mixing in step(c) generally occurs less than one
minute. For instance, the mixing in step(c) can occur from 1 to 20 seconds.
The stability of the post-diluted composition varies. For instance, the
stability of the post-diluted composition can be stable from 1 to 6 hours.
The method of the invention provides valuable advantages. For
instance, the paper sized in accordance with the invention generally exhibits
a
sizing efficiency that is more than 20% higher, as compared to paper made
with a composition that is not subjected to a post-dilution step. The paper
that
can be sized with the method of the invention can be selected from the group
consisting of paperboard papers, fine papers, newsprint papers, and
combinations thereof.
As such, the invention can also be directed to the papers treated with
Applicants' invention.
The invention is further described in the following illustrative examples
in which all parts and percentages are by weight unless otherwise indicated.
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EXAMPLES
Handsheets Studies - Examples 1-12
Evaluation of a low shear alkenylsuccinic anhydride (ASA)
performance was done by preparation of ASA emulsions with water, polymers
or starch, characterization of the emulsion particle size distribution,
addition of
these emulsions to the paper furnish, forming paper handsheets and
measuring the sizing of paper handsheets. The performance of the low shear
emulsion was compared to a conventional, high shear ASA emulsion.
Emulsification of Low Shear ASA in Water Using a Centrifugal Pump-
Method 1
Alkenylsuccinic anhydride (ASA) containing 5% Brij 98 surfactant was
emulsified in water with a single impeller, open-feed, 1-horespower
centrifugal
pump at a speed of 1700 rpm. The low shear centrifugal pump was connected
to a tap water supply and the pump was operated using the pressure from the
tap water supply. No pH or temperature adjustment was made to the tap
water prior to emulsification. ASA was supplied to the centrifugal pump from a
calibration column via a gear pump. ASA entered the water inlet just before
the centrifugal pump. The water flow rate was approximately 1 L/min and ASA
flow rate was approximately 240 mL/min. The centrifugai pump was a single-
pass emulsification process with no recirculation. The resulting ASA emulsion
contained 19 weight percent ASA.
Emulsification of Low Shear ASA in Polymer or Starch Solution Using a
Centrifugal Pump - Method 2
The emulsification of ASA containing 5% Brij 98 surfactant in polymer
or starch solution was done as the emulsification in water, except that
polymer
or starch were added to a water line using a variable speed gear pump, and it
was mixed using an in-line static mixer before it was combined with ASA flow.
The centrifugal pump was run at a speed between 1700 and 3600 rpm. The
concentration of ASA in the emulsion varied from about 3 to about 10 wt %,
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depending on particular study. The total flow rate of water, ASA and polymer
or starch was about I L/min.
Emulsification of ASA with Hiah Shear
A high shear ASA, BAYSIZE 1 18 size (LANXESS Corporation)
emulsion were prepared with a polymer or starch solution using a household
blender on high speed for 90 -180 sec. See details in examples.
Emulsion Particle Size Analysis
A commercially available, light scattering, particle analyzer, Horiba LA-
300 was used to determine the particle size of the emulsions. Results are
reported as the median particle size in microns.
Handsheet Preparation Process Used in Examples 1-10
Handsheets were prepared using a furnish of a 50/50 mixture of
bleached hardwood and softwood kraft pulp refined to a Canadian Standard
Freeness (CSF) of 500 mL to which 10 % by weight of precipitated calcium
carbonate was added, and pH was adjusted to 7.8.
Deionized water was used for furnish preparation and additional 80
ppm of sodium sulfate and 50 ppm of calcium chloride were added.
While mixing, a batch of pulp at 0.71 % solids containing 17 g of
cellulose fibers and calcium carbonate was treated with an ASA emulsion that
was diluted to 0.25 wt.% with tap water. Alum was also added to the batch
and applied at a dose of 5 lb per ton of dry fiber. Alum was applied 30 sec
prior to ASA emulsion addition. After a 60-sec contact time, 1 lb per ton on
dry
fiber of an anionic retention aid was added, and mixing continued for 15 sec.
Three 5.0 g sheets of paper were formed using a standard (8"x8")
Nobel & Woods handsheet mold, to target a basis weight of 121 g/m2. Each
sheet was pressed between felts in the nip of a pneumatic roll press at about
15 psig and dried on a rotary dryer at 240 F.
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PAPER SIZING EVALUATION PROCEDURES
A 2-min Cobb test or Ink Penetration Holdout test was used to evaluate
the sizing paper.
2-MIN COBB TEST
The sizing of handsheets was tested using a 2-min Cobb test. The test
was performed according to TAPPI Test Method T441 om-90. A 100-cm2 ring
was utilized in this test.
INK PENETRATION HOLDOUT
Ink Penetration Holdout was measured using a method similar to that
described in TAPPI Method T 530 pm-89 except that an instrument was used
as described in U.S. Pat. No. 5,483,078. The test measures the time (in
seconds) for the reflectance of the paper on the side opposite that contacting
the ink to decreases to 80% of the initial value. The ink consists of 1.25%
Napthol Green B dye buffered to pH 7. The test values were normalized for
basis weight of the paper assuming that the values vary as the cube of the
basis weight. Results were expressed in units of seconds.
EXAMPLE 1
ASA containing 5 wt % of Brij 98 surfactant was emulsified in an
aqueous solution of the high molecular weight cationic acrylamide polymer,
BAYSIZE E LS polymer (LANXESS Corporation) at a sizing agent to polymer
solids ratio of 1/0.1.
The emulsification was done according to Method 2, using a centrifugal
pump at a speed of 3000 rpm. During the emulsification process, the ASA
flow was 53 mL/min, the 10.8 %(w/w) polymer solution flow was 47 mL/min,
and water flow was 1030 mL/min. The sizing agent concentration in the
emulsion was 4.88 % (w/w). The emulsion particle size was 1.18 microns. The
handsheets were prepared with this emulsion and the sizing of these
handsheets was measured using a 2-min Cobb test.
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EXAMPLE 2 (COMPARATIVE)
BAYSIZE 1 18 size (LANXESS Corporation) was emulsified in the
aqueous solution of the high molecular weight cationic acrylamide polymer
BAYSIZE E LS polymer (LANXESS Corporation) at a sizing agent to polymer
solids ratio of 1/0.1. During the emulsification process, 20.2g of
BAYSIZE 1 18 size (LANXESS Corporation) was added to 100 g of 2.02(w/w)
polymer solution and mixed in a household blender on high speed for 3 min.
The emulsion particle size was 0.72 microns. The handsheets were prepared
with this emulsion and the sizing of these handsheets was measured using a
2-min Cobb test.
Table 1. Performance of Sizing Agents Emulsified with a High
Molecular Weight Cationic Polymer.
Example 2-min Cobb Sizing (g/m )
4.25 lb/t of 5.25 lb/t of 6.25 Ib/t of 4.25 lb/t of
sizing agent sizing agent sizing agent sizing agent;
5 Ib/t of alum
Examplel 54.5 35 30.5 26.5
Example 2 38.0 28.5 30.0 25.5
(comparative)
The emulsion of a low shear ASA (Example 1) provided worse paper
sizing than the high shear ASA emulsion (Example 2) at a low sizing agent
dose, but as the dose was increased or as 5 lb/t of alum was applied, the
sizing performance of both sizing agents was equivalent.
EXAMPLE 3
ASA containing 5 % (w/w) of Brij 98 surfactant was emulsified in the
aqueous solution of the low molecular weight cationic acrylamide polymer
BAYSIZE E HE polymer (LANXESS Corporation) at a sizing agent to
polymer solids ratio of 1/0.15.
The emulsification was done according to Method 2, using a centrifugal
pump at a speed of 1700 rpm. During the emulsification process, the ASA
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flow was 50 mL/min, the 26-wt. % polymer solution flow was 26 mL/min, and
water flow was 1909 mL/min. The sizing agent concentration in the emulsion
was 4.8 wt. %. The emulsion particle size was 2.3 microns. The handsheets
were prepared with this emulsion, and the sizing of these handsheets was
measured using a 2-min Cobb test.
EXAMPLE 4 (COMPARATIVE)
BAYSIZE 1 18 size (LANXESS Corporation) was emulsified in the
aqueous solution of the low molecular weight cationic acrylamide polymer
BAYSIZE E HE polymer (LANXESS Corporation) at a sizing agent to polymer
solids ratio of 1/0.15. During the emulsification process, 20.2 g of BAYSIZE I
18 size (LANXESS Corporation) was added to 101 g of 3% (w/w) polymer
solution and mixed in a household blender on high speed for 3 min. The
emulsion particle size was 1.1 microns. The handsheets were prepared with
this emulsion, and the sizing of these handsheets was measured using a 2-
min Cobb test.
Table 2. Performance of Sizing Agents Emulsified with a Low
Molecular Weight Cationic Polymer.
Example 2-min Cobb Sizing (g/m )
4.5 Ib/t of 5.5 Ib/t of 6.5 lb/t of 4.5 Ib/t of
sizing agent sizing agent sizing agent sizing agent,
5 Ib/t of alum
Example 3 104.5 73.0 28.0 25.5
Example 4 66 36.5 29.5 26.5
(comparative)
The sizing performance of the low shear ASA emulsified with the low
molecular weight cationic polymer (Example 3) matched the performance of
the high shear ASA emulsified with the same low molecular cationic polymer
(Example 4) when a higher dose of sizing agent was used. The sizing
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performance was also matched when a lower dose of sizing agent was used
in conjunction with alum.
EXAMPLE 5
ASA containing 5%(w/w) of Brij 98 surfactant was emulsified in a
solution of Hi-Cat CWS pregelatinized starch (Roquette) at a sizing agent to
starch solids ratio of 1/1. The emulsification was done according to Method 2,
using a centrifugal pump at a speed of 2400 rpm. During the emulsification
process, the ASA flow was 44.5 mL/min, the 4.19% (w/w) starch solution flow
was 955.5 mUmin, and there was no water flow. The sizing agent
concentration in the emulsion was 4.21 % (w/w). The emulsion particle size
was 3.6 microns. The handsheets were prepared with this emulsion, and the
sizing of these handsheets was measured using a 2-min Cobb test.
EXAMPLE 6
ASA containing 5%(w/w) of Brij 98 surfactant was emulsified in tap
water.
The emulsification was done according to Method 1, using a centrifugal
pump at a speed of 1700 rpm. During the emulsification process, the ASA
flow was 44.5 mUmin, the water flow was 955.5 mL/min. The sizing agent
concentration in the emulsion was 4.2 % (w/w). The emulsion particle size
was 1.5 microns. The emulsion was post-diluted with the 4.19% (w/w) solution
of Hi-Cat CWS pregelatinized starch (Roquette). The sizing agent to starch
solids ratio in the post-diluted emulsion was 1/1. The handsheets were
prepared with this emulsion, and the sizing of these handsheets was
measured using a 2-min Cobb test.
EXAMPLE 7 (COMPARATIVE)
BAYSIZE 1 18 size (LANXESS Corporation) was emulsified in an
aqueous solution of Hi-Cat CWS pregelatinized starch (Roquette) at a sizing
agent to starch solids ratio of 1/1.
During the emulsification process, 8.08 g of BAYSIZE 1 18 size
(LANXESS Corporation) was added to 191.92 g of the 4.19% (w/w) starch
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solution and mixed in a household blender on high speed for 90 seconds. The
emulsion particle size was 0.62 microns.
The handsheets were prepared with this emulsion, and the sizing of these
handsheets was measured using a 2-min Cobb test.
Table 3. Performance of Sizing Agents Emulsified in Starch or Post-
diluted with Starch.
Example 2-min Cobb Sizing (g/m )
4.25 Ib/t of 5.25 Ib/t of 6.25 Ib/t of
sizing agent sizing agent sizing agent
Example 5 44.0 26.5 27.0
Example 6 137.5 72.5 33.5
Example 7 34.0 27.0 25.5
(comparative)
The low shear ASA emulsified in a cationic starch solution (Example 5)
provided similar performance to the high shear ASA emulsified in the same
starch solution (Example 7). Worse performance was achieved when the low
shear ASA was emulsified in water and post-diluted with starch solution to
provide the sizing agent to starch solids ratio of 1/1.
EXAMPLE 8
The amount of 6.0 g of ASA containing 5 wt % of Brij 98 surfactant was
emulsified with 114 g of 0.53 % (w/w) aqueous solution BAYSIZE E HE
polymer (LANXESS Corporation), using a household blender on low speed for
30 second. The emulsion particle size was 1.3 microns. The handsheets were
prepared with this emulsion. During the handsheets making process, each set
was treated with 5 lb/t of alum. The sizing of these handsheets was measured
using a 2-min Cobb test.
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EXAMPLE 9
ASA, 6.0 g, containing 5 % (w/w) of Brij 98 surfactant was emulsified in
114.0 g of tap water, using a household blender on low speed for 30 second.
The emulsion particle size was 0.95 microns. Ten grams of the emulsion was
post-diluted with 190 g of 0.026-wt. % aqueous solution of the low molecular
weight cationic acrylamide polymer BAYSIZE E HE polymer (LANXESS
Corporation). The handsheets were prepared with this emulsion. During the
handsheets making process, each set was treated with 5 lb/t of alum. The
sizing of these handsheets was measured using a 2-min Cobb test.
EXAMPLE 10 (COMPARATIVE)
BAYSIZE 1 18 size (LANXESS Corporation) was emulsified in the
aqueous solution of the low molecular weight cationic acrylamide polymer
BAYSIZE E HE polymer (LANXESS Corporation) at a sizing agent to polymer
solids ratio of 1/0.1. During the emulsification process, 20 g of BAYSIZE 1 18
size (LANXESS Corporation) was added to 100 g of 2%(w/w) polymer
solution and mixed in a household blender on high speed for 3 min. The
emulsion particle size was 1.0 micron. The handsheets were prepared with
this emulsion. During the handsheets making process, each set was treated
with 5 lb/t of alum. The sizing of these handsheets was measured using a 2-
min Cobb test.
Table 4. Performance of Sizing Agents Emulsified or Post-diluted with
a Low Molecular Weight Cationic Polymer.
Example 2-min Cobb Sizing (g/m )
4.0 lb/t of 5.0 lb/t of sizing 6.0 lb/t of
sizing agent; agent; sizing agent;
5 Ib/t of alum 5 Ib/t of alum 5 lb/t of alum
Example 8 24.6 18.8 26.9
Example 9 35.0 27.4 15.3
Example 10 25.7 24.4 24.1
(comparative)
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As this is shown in Table 4, the application of alum in the handsheets
making process improved the performance of a low shear ASA. The
performance of the low shear ASA emulsified in the low molecular weight
cationic polymer (Example 8) provided comparable performance to the high
shear ASA (Example 10) over the broad dose range. The low shear ASA that
was emulsified in water and post-diluted with the polymer solution (Example
9) provided worse sizing than ASA emulsified with the polymer, but the
difference in the performance was rather small.
EXAMPLE 11
ASA, 6.0 g, containing 5%(w/w) of Brij 98 surfactant was emulsified in
114.0 g of tap water, using a household blender on low speed for 30 second.
The emulsion particle size was 1.03 microns. The emulsion was post-diluted
to 0.25 % (w/w) with tap water, and than mixed with a 1 /a (w/w) cationic
starch solution. The 82 g/m2 basis weight handsheets were prepared with this
emulsion. Handsheets were made with the recycled furnish obtained from a
board mill. During the handsheet-making process, each set was first treated
with polyaluminum chloride at a dose of 12 lb/t of dry fiber. After 30 sec,
the
mixture of ASA emulsion and starch was added to the furnish. The mixture of
ASA emulsion provided 20 lb of dry starch per ton of dry fiber. After a 60-sec
contact time, an anionic retention aid was added at a dose of 1 lb/t of dry
fiber, and mixing continued for 15 sec. Ink Penetration Holdout was used to
evaluate the paper sizing.
EXAMPLE 12 (COMPARATIVE)
This example was like Example 11, except that the ASA emulsion and
the starch solution was added separately to the furnish. ASA, 6.0 g,
containing 5 % (w/w) of Brij 98 surfactant was emulsified in 114.0 g of tap
water, using a household blender on low speed for 30 sec. The emulsion
particle size was 1.03 microns. The handsheets were prepared with this
emulsion. Handsheets were made with recycled furnish. During the
handsheet-making process, each set was first treated with polyaluminium
chloride at a dose of 12 lb per ton of dry fiber. After 30 sec, the ASA
emulsion
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was added and mixed with furnish for 5 sec before 20 lb of cationic starch per
ton of dry fiber was added. After 55 sec, 1 lb of an anionic retention aid per
ton of dry fiber was added, and mixing continued for 15 sec. Ink Penetration
Holdout was used to evaluate paper sizing.
Table 5. Post-dilution of Low Shear ASA Emulsion with Starch vs.
Separate Addition of ASA Emulsion and Starch to the Furnish.
Example Neutral Ink Holdout (sec)
0.12 Ib/t of 0.25 lb/t of 0.5 lb/t of sizing
sizing agent sizing agent agent
Example 11 308 740 2197
Example 12 240 259 354
(comparative)
The post-dilution of the low shear ASA emulsion with cationic starch
solution prior to the addition of ASA emulsion to the furnish (Example 11)
provided significantly higher paper sizing than the separate addition of ASA
emulsion and starch to the furnish (Example12).
EXAMPLE 13-17
Evaluation of low shear alkenyisuccinic anhydride (ASA) performance
was done by preparation of ASA emulsions in water or in a polymer solution,
or post-dilution of ASA emulsified in water with starch or polymer solution,
and
addition of these emulsions to the paper furnish during a pilot machine paper
making process. The sizing performance of the low shear emulsion was
compared to a conventional, high shear ASA emulsion, using a 2-min Cobb
test.
PAPER FURNISH
A 30/70 blend of bleached northern softwood Kraft refined to 420 mL
CSF and bleached northern hardwood Kraft refined to 350 mL CSF was
applied in the pilot machine papermaking process. Precipitated calcium
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carbonate was added to the machine chest in the amount of 10 wt. % on dry
fiber. The basis weight of the paper produced on the pilot machine was 120
gm2.
Pilot Paper Machine Operating Conditions
The pilot machine speed is 85 feet per minute, giving a production rate
of about 1.16 Ib/min. The pH of the paper furnish was maintained between 7.9
and 8.4. The ASA emulsions were diluted with tap water to 0.5 % (w/w)
concentration before the addition to the paper furnish. An anionic retention
aid
in the amount of 0.5 lb per ton of dry paper was applied. The paper moisture
content was 4%(w/w) at the reel.
EXAMPLE 13
ASA containing 5 % (w/w) of Brij 98 surfactant was emulsified in an
aqueous solution of the low molecular weight cationic acrylamide polymer
BAYSIZE E HE polymer (LANXESS Corporation) at a sizing agent to polymer
solids ratio of 1/0.12.
The emulsification was done according to Method 2, using a centrifugal
pump at a speed of 3300 rpm. During the emulsification process, the ASA
flow was 50mL/min, the 13.27% (w/w) polymer solution flow was 40 mUmin,
and water flow was 810 mL/min. The sizing agent concentration in the
emulsion was 5.26 % (w/w). The emulsion particle size was 1.17 microns.
This emulsion was applied as an internal sizing agent to produce paper on the
pilot paper machine. The sizing of the felt and wire side of this paper was
measured using a 2-min Cobb test.
EXAMPLE 14
ASA containing 5%(w/w) of Brij 98 surfactant was emulsified in tap
water.
The emulsification was done according to Method 1, using a centrifugal
pump at a speed of 1700 rpm. During the emulsification process, the ASA
flow was 50.0 mL/min, the water flow was 850 mL/min. The sizing agent
concentration in the emulsion was 5.26 % (w/w). The emulsion particle size
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was 1.44 microns. The emulsion was post-diluted with the 0.05% (w/w) of
BAYSIZE E HE polymer (LANXESS Corporation). The sizing agent to polymer
solids ratio in the post-diluted emulsion was 1/0.1, and the ASA concentration
was 0.5 wt. %. This emulsion was applied as an internal sizing agent to
produce paper on the pilot paper machine. The sizing of the felt and wire side
of this paper was measured using a 2-min Cobb test.
EXAMPLE 15 (COMPARATIVE)
BAYSIZE 1 18 size (LANXESS Corporation) was emulsified in the
aqueous solution of the low molecular weight cationic acrylamide polymer
BAYSIZE E HE polymer (LANXESS Corporation) at a sizing agent to polymer
solids ratio of 1/0.1. During the emulsification process, 240 g of BAYSIZE 1
18
size (LANXESS Corporation) was added to 180.86 g of a 13.25 % (w/w)
polymer solution and 1019.71 g of tap water, and the mixture stirred in an
industrial blender on low speed for 1.5 min. The emulsion particle size was
1.15 microns. Handsheets were prepared with this emulsion. This emulsion
was applied as an internal sizing agent to produce paper on the pilot paper
machine. The sizing of the felt and wire side of this paper was measured
using a 2-min Cobb test.
Table 5. Performance of Sizing Agents Emulsified with a Low
Molecular Weight Cationic Polymer. Data from the Pilot Machine Trial.
Example 2-min Cobb Sizing (g/m )
4.0 Ib/t of 5.0 Ib/t of 6.0 Ib/t of 4.0 Ib/t of 5.0 Ib/t of
sizing agent sizing agent sizing agent sizing agent; sizing ager
5 lb/t of alum 5 lb/t of alt
Example 13 119.8 77.5 39.6 31.5 32
Example 14 49.5
Example 15 124.8 87.5 43.8 39.5 34.5
(comparative)
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The low shear ASA (Example 13) provided slightly better sizing than
the high shear ASA (Example 15) over a broad dose range when both sizing
agents were applied at the wet-end of paper making process on the pilot
machine. The low shear ASA emulsified in water and post-diluted with a
cationic polymer solution (Example 14) provided a good sizing response,
however the sizing was lower than the sizing obtained with the low shear ASA
emulsified in the polymer solution (Example 13).
E)CAMPLE 16
ASA containing 5%(w/w) of Brij 98 surfactant was emulsified in tap
water, as it was described in Example 14. The emulsion was post-diluted with
a 2.2. % (w/w) solution of the Hi-Cat CWS pregelatinized starch (Roquette).
The sizing agent to starch solids ratio in the post-diluted emulsion was 1/4,
and the ASA concentration was 0.5% (w/w). This emulsion was applied as an
internal sizing agent to produce paper on the pilot paper machine. The sizing
of the felt and wire side of this paper was measured using a 2-min Cobb test.
EXAMPLE 17 (COMPARATIVE)
BAYSIZE 1 18 size (LANXESS Corporation) was emulsified in an
aqueous solution of the Hi-Cat CWS pregelatinized starch (Roquette) at a
sizing agent to starch solids ratio of 1/1. During the emulsification process,
80
g of BAYSIZE 1 18 size (LANXESS Corporation) was added to 1920 g of
4.17% (w/w) starch solution and mixed in an industrial blender on low speed
for 30 sec. The emulsion particle size was 1.37 microns. The emulsion was
post-diluted with a 1.7% (w/w) solution of the Hi-Cat CWS pregelatinized
starch (Roquette). The sizing agent to starch solids ratio in the post-diluted
emulsion was 1/4, and the ASA concentration was 0.5% (w/w). The
handsheets were prepared with this emulsion. This emulsion was applied as
an internal sizing agent to produce paper on the pilot paper machine. The
sizing of the felt and wire side of this paper was measured using a 2-min
Cobb test.
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Table 6. Performance of Sizing Agents Emulsified in Starch or Post-
diluted with Starch.
Example 2-min Cobb Sizing (g/m )
4.0 Ib/t of 7.0 Ib/t of 8.0 Ib/t of
sizing agent sizing agent sizing agent
Example 16 41.3 36.5 32.3
Example 17 29.8
(comparative)
The results in Table 6 indicate that the low shear ASA post-diluted with
the cationic starch is less effective in terms paper sizing as the high shear
ASA emulsified in the cationic starch. However, the simplicity of the
emulsification process of the low shear ASA and acceptable sizing response
gives the paper maker operational and cost benefits in using this system.
Although the present invention has been described in detail with
reference to certain preferred versions thereof, other variations are
possible.
Therefore, the spirit and scope of the appended claims should not be limited
to the description of the versions contained therein.
