Note: Descriptions are shown in the official language in which they were submitted.
CA 02204050 1997-04-30
Background of the Invention
I. Field of the Invention
The present invention is in the technical field of papermaking and more
particularly in the technical field of wet-end additives to papermaking
furnish.
2. Descri lion of the Prior Art
In the manufacture of paper an aqueous cellulosic suspension or slurry is
formed
into a paper sheet. The cellulosic slurry is generally diluted to a
consistency (percent dry
wei_ht of solids in the slum') of less than 1 percent and often below 0.5
percent ahead of
the paper machine, while the finished sheet must have less then 6 weight
percent water.
Hence the dewatering aspects of papermaking are extremely important to the
efficiency
and cost of the manufacture.
The dewatering method of the least cost in the process is drainage, and
thereafter
more expensive methods are used, for instance vacuum, pressing, evaporation
and the
1 ~ like. and in practice a combination of such methods are employed to
dewater, or dry the
sheet to the desired water content. Since drainage is both the first
dewatering method
employed and the least expensive. improvement in the efficiency of drainage
will
decrease the amount of water required to be removed by other methods and hence
improve the overall efficiency of dewatering and reduce the cost thereof.
Another aspect of papermaking that is extremely important to the efficiency
and
cost of the manufacture is retention of furnish components on and within the
fiber mat
being formed during papermaking. A papermaking furnish contains generally
panicles
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that range in size from about the 2 to 3 millimeter size of cellulosic fibers,
to fillers at a
few microns, and to colloids. Within this range are cellulosic fines, mineral
fillers
(employed to increase opacity, brightness and other paper characteristics) and
other small
particles that generally, without the inclusion of one or more retention aids,
would in
significant portion pass through the spaces (pores) between the cellulosic
fibers in the
fiber mat being formed during papermal:ing.
One method of improving the retention of cellulosic fines, mineral fillers and
other furnish components on the fiber mat is the use of a coagulant/flocculant
system,
added ahead of the paper machine. In such a system there is first added a
coagulant, for
instance a low molecular weight cationic synthetic polymer or a cationic
starch to the
furnish. which coagulant generally reduces the negative surface charges
present on the
particles in the furnish, particularly cellulosic fines and mineral fillers,
and thereby
accomplishes a degree of agglomeration of such particles, followed by the
addition of a
flocculant. Such flocculant generally is a high molecular weight anionic
synthetic
1 s polymer which bridges the particles and/or agglomerates, from one surface
to another,
bindin~_ the particles into large agglomerates. The presence of such large
agglomerates in
the furnish as the fiber mat of the paper sheet is being formed increases
retention. The
ag;~lomerates are filtered out of the water onto the fiber web, where
unagglomerated
particles would to a great extent pass through such paper web.
While a flocculated agglomerate generally does not interfere with the drainage
of
the fiber mat to the extent that would occur if the furnish were gelled or
contained an
amount of gelatinous material, when such flocs are filtered by the fiber web
the pores
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thereof are to a degree reduced, reducing the drainage efficiency therefrom.
Hence the
retention is being increased with some degree of deleterious effect on the
drainage..
Aziother system employed to provide an improved combination of retention and
dewatenng is described in United States Patent No. 4,73,710 and United States
Patent
No. 4,913,77, inventors Langley et al., issued respectively June 28, 1988 and
April 3, 1990. In brief, such method adds to the aqueous cellulosic
papermaking suspension first a high molecular weight linear cationic polymer
before shearing the suspension, followed by the addition of bentonite after
shearing. The
shearing generally is provided by one or more of the cleaning, mixing and
pumping
stages of the papei~making process, and the shearing breaks down the large
flocs formed
by the high molecular weight polymer into microflocs, and further
agglomeration then
ensues with the addition of the bentonite clay particles.
Another system uses the combination of cationic starch followed by colloidal
silica to increase the amount of material retained on the web by the method of
charge
1 ~ neutralization and adsorption of smaller agglomerates. This system is
described in
United States Patent No. 4,388.1 ~0, inventors Sunden et al.; issued June 14,
1983.
Dewatering generally. and particularly dewatering by drainage, is believed
improved when the pores of the paper web are less plugged, and it is believed
that
retention by adsorption in comparison to retention by filtration reduces such
pore
plugging.
Greater retention of fines and fillers permits, for a given grade of paper, a
reduction in the cellulosic fiber content of 'such paper. As pulps of less
quality are
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CA 02204050 1997-04-30
employed to reduce papermaking costs, the retention aspect of papermal:ing
becomes
even more important because the fines content of such lower quality pulps is
greater
generally than that of pulps of higher quality.
Greater retention of fines, fillers and other slurry components reduces the
amount
of such substances lost to the white water and hence reduces the amount of
material
wastes, the cost of waste disposal and the adverse environmental effects
therefrom.
Another important characteristic of a given papermaking process is the
formation
of the paper sheet produced. Formation is determined by the variance in light
transmission within a paper sheet, and a high variance is indicative of poor
formation. As
retention increases to a high level, for instance a retention level of 80 to
90 percent, the
formation parameter generally abruptly declines from good formation to poor
formation.
It is at least theoretically believed that as the retention mechanisms of a
given
papermaking process shift from filtration to adsorption, the deleterious
effect on
formation. as high retention levels are achieved. will diminish, and a good
combination of
1 ~ hi~_h retention with 2ood formation is attributed to the use of bentonite
in U. S. Patent No.
4.913.77.
It is generally desirable to reduce the amount of material employed in a
papermaking process for a given purpose, without diminishing the result
sought. Such
add-on reductions may realize both a material cost savings and handling and
processing
benefits.
It is also desirable to use additives that can be delivered to the paper
machine
without undue problems. An additive that is difficult to dissolve, slurry or
otherwise
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disperse in the aqueous medium may require expensive
equipment to feed it to the paper machine. When
difficulties in delivery to the paper machine are
encountered, the additive is often maintained in aqueous
slurry form by virtue of high energy input equipment. In
contrast, additives that are easily dissolved or dispersed
in water require less energy and expense and their
uniformity of feed is more reliable.
Summary of the Invention
The invention comprises a papermaking process
comprising forming an aqueous cellulosic papermaking slurry,
subjecting the slurry to one or more shear stages, adding to
the slurry a mineral filler prior to at least one of the
shear stages, adding to the slurry after the addition of the
mineral filler and prior to at least one of the shear stages
an effective amount of a dispersion polymer selected from
the group consisting of copolymers of acrylamide and
dimethylaminoethylacrylate methyl chloride quaternary salt
(DMAEA.MCQ), dimethylaminoethylmethacrylate methyl chloride
quaternary salt (DMAEM.MCQ), dimethylaminoethylacrylate
benzyl chloride quaternary salt (DMAEA.BCQ) and
dimethylaminoethylmethacrylate benzyl chloride quaternary
salt (DMAEM.BCQ) and diallyldimethylammonium chloride
(DADMAC), shearing the slurry, adding a microparticle
selected from the group consisting of organics such as
copolymers of acrylic acid, inorganics such as bentonite and
silica sol, draining the slurry to form a sheet, and drying
the sheet to form a paper sheet.
In one aspect, the invention provides a
papermaking process, comprising: forming an aqueous
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cellulosic papermaking slurry; subjecting the slurry to one
or more shear stages; adding to the slurry a mineral filler
prior to at least one of the shear stages; adding to the
slurry after the addition of the mineral filler and prior to
at least one of the shear stages from 0.5 to 100 ppm by
weight of dry pulp contained in the slurry of a cationic
dispersion polymer obtained by dispersion polymerization of
a monomer mixture soluble in an aqueous solution of a
polyvalent anionic salt said polymer being selected from the
group consisting of copolymers of acrylamide and
dimethylaminoethylacrylate methyl chloride quaternary salt,
dimethylaminoethylmethacrylate methyl chloride quaternary
salt, dimethylaminoethylacrylate benzyl chloride quaternary
salt and dimethylaminoethylmethacrylate benzyl chloride
quaternary salt and wherein said polymer is insoluble in the
aqueous solution; shearing the slurry; adding microparticles
selected from the group consisting of a copolymer of acrylic
acid, bentonite and silica sot to the slurry; draining the
slurry to form a sheet; and drying the sheet to form a paper
sheet.
Brief Description of the Drawings
FIG. 1 is a plot of Filtrate Weight vs. Time for
an alkaline test stock in which Polymer A and Polymer D are
compared, with and without the addition of Microparticle A.
FIG. 2 is a plot of Filtrate Weight vs. Time for
an alkaline test stock in which Polymer B and Polymer D are
compared, with and without the addition of Microparticle A.
FIG. 3 is a plot of Filtrate Weight vs. Time for
an acid test stock in which Polymer A and Polymer D are
compared, with and without the addition of two different
levels of Microparticle A.
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66530-619
FIG. 4 is a plot of Filtrate Weight vs. Time for
an acid test stock in which Polymer A and Polymer D are
compared, with and without the addition of Microparticle B.
FIG. 5 is a plot of Filtrate Weight vs. Time for a
corrugated coated test stock in which the effect of Polymer
A is compared to no polymer being present and is also
compared to Polymer A being present with Microparticle A.
FIG. 6 is a plot of Filtrate Weight vs. Time for a
corrugated coated test stock in which the effect of Polymer
A is compared to no polymer being present and is also
compared to Polymer A being present with Microparticle B.
FIG. 7 is a plot of Filtrate Weight vs. Time for
an alkaline test stock in which Polymer A and Polymer D are
compared, with and without the addition of Microparticle C.
Description of the Preferred Embodiments
According to the invention, a water soluble
polymer is added to a cellulosic slurry before the formation
of a paper product. The water soluble polymer should become
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CA 02204050 1997-04-30
substantially dispersed within the slurry before formation of the paper
product in any
case. The microparticle of the invention is added after shearing of the
slurry. The
addition of the polymer in an aqueous medium, for instance as a water solution
or
dispersing, facilitates the dispersion of the polymer of the slurry. In a
preferred
embodiment, the polymer is added to the cellulosic slurry before the
processing steps of
draining and forming the paper sheet.
The present process is believed applicable to all grades and types of paper
products, and further applicable for use on all types of pulps including,
without
limitation. chemical pulps, including sulfate and sulfite pulps from both hard
and soft
woods and acid pulps, thermo-mechanical pulps, mechanical pulps, recycle pulps
and
eround wood pulps, although it is believed that the advantages of the process
of the
present invention are best achieved when the pulp employed is of the chemical
pulp type,
particularly alkaline chemical pulp.
In preferred embodiment the filler used in the cellulosic slurry is anionic,
or at
1 ~ least partially anionic. Other mineral, or inorganic, fillers may,
however, be used, such as
calcium carbonate. clay. titanium dioxide, or talc or a combination may be
present.
The amount of alkaline inorganic filler. such as one of the alkaline
carbonates,
generally employed in a papermaking stock is from about 10 to about 30 parts
by weight
of the filler, as CaCOj, per hundred pans by weight of dry pulp in the slurry,
but the
amount of such filler may at times be as low as about 5, or even about 2,
parts by weight,
and as high as about 40 or even ~0 parts by weight, same basis.
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The reduced specific viscosities of the polymers and copolymers as reported
herein were determined in 0.125M sodium nitrate solution from published data.
Similarly, all molecular weights of the polymers as reported herein are the
approximate
weight average molecular weights of the polymers.
The dispersion polymerization process used to manufacture the polymers of the
invention offer numerous advantages which have previously been unavailable.
Since the
polymers of the invention are synthesized entirely in water, no oil solvent is
required.
This is sienificant since:
1 ) the polymers of the invention do not present a fire hazard;
2) oil is not added to the water which is to be treated (more environmental
friendly);
3) dissolution of the polymers of the invention requires only the addition of
water,
no special activators are needed;
4) the ability of the polymers of the invention to dissolve/invert is superior
to that of
oil dispersion latexes; and
1 > p) the polymers of the invention may be diluted to virtually any
concentration by
using appropriately concentrated salt water.
Another major advantage is that the bulk viscosity of the polymer is low,
unlike
some oil dispersion latex polymers. This physical property enables any
standard
chemical pump to deliver the material at the injunction site.
A new class of water-soluble dispersion polymers have been discovered to be
more effective in increasing drainaue and retention than currently available
chemical
treatments. As will be discussed in more detail below, the polymer dispersion
of the
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invention is prepared in an aqueous solution of a polyvalent anionic salt. The
polymer
dispersion of the invention achieves fine particle sizes and
aqueouswsolubilities not
available with other polymers used for this application. Furthermore, there
does not
appear~o be a problem with overfeeding the polymer dispersion which is a
drawback
with latex polymers.
According to the method. the dispersion polymer of the invention is added to a
cellulosic papermaking slurry. The polymer is added in an effective amount of
from 0.~.
to about 100 ppm. More preferably, the amount of the polymer added is from 2
to about
40 ppm: and most preferably from about 4 to about 2~ ppm. It is believed; that
there does
not appear to be a,maaimum dosage at which the polyrrters adversely affect the
system.
At some higher doses the beneficial effect may plateau, and on a cost basis
such higher
doses, probably above about 100 ppm, are not cost effective. The polymers of
the
invention are preferably added to the system in neat form. However, in some
applications. the polymers can be added as an aqueous solution.
1 ~ The preferred polymers of the invention are manufactwed by Hymo
Corporation,
Japan. Methods for manufacturing the polymer dispersion used in the invention
is
described in detail in U. S. Patent No. ~.006.~90 and U. S. Patent No.
4,929,655, assigned
to Kyoritsu Yuki Co., Ltd., Tokyo. Japan.
In the preferred embodiment of the invention, an organic or inorganic
microparticle is added to the slumr after the introduction of shear.
Preferably, the organic
microparticle is a medium molecular weight anionic polymer such as the
copolymers of
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66530-619
acrylic acid described in U.S. Patent No. 5,098,520, or medium molecular
weight anionic sulfonated polymers such as those described in U.S. Patent
No. 5,185,062. The inorganic microparticle may be preferably chosen
from among bentonite and silica sol.
According to the invention, the dispersion polymer used to treat.the
cellulosic
papermaking slurry may further be prepared from a water-soluble monomer
mixture
' containing at least ~ mole % of a cationic monomer represented by the
general formula
(I):
R
CH,=C R~
Q
O= At gt N CHZ X
i ~ ~ cI)
R
wherein Ri is H or CH3; R= and R3 are each an alkyl group having 1 to 2 carbon
atoms;
A, is an oxygen atom or NH: B, is an alkyl group having 2 to 4 carbon atoms or
a
1 ~ hydroxypropyl group and X, is a counter anion.
'The above water-soluble monomer mixture is soluble in the aqueous solution of
the polyvalent anionic salt. 'The polymer generated from the monomer mixture
is,
however, insoluble in the aqueous polyvalent anionic salt solution. The
polymer of the
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monomer mixture can also be used as the seed polymer. The seed polymer is
described
in detail below.
The above cationic monomer represented by the general fotmtula (I) preferably
is
a quaternary ammonium salt obtained by the reaction of methyl chloride or
benzyl
chloride and dimethylaminoethyl acrylate, diethylaminoethyl acrylate,
dimethylaminohydroxypropyl acrylate, dimethylaminopropyl acrylamide,
dimethylaminoethyl methacrylate, dimethylaminoethyl methacrylate,
diethylaminoethyl
methacrr~late and dimethylaminopropyl methacrylamide.
The concentration of the above-mentioned monomers in the polymerization
reaction mixture is suitably in the range of 1.0 to 30% by weight for the
methyl chloride
quaternary ammonium salt. Preferably, the concentration is from about 10 to
about 20%
by weight. For the benzyl chloride quaternary ammonitun salts, the
concentration in the
polymerization reaction mixture is suitably in the range of from about 1.0 to
about 3~%
by weight. Preferably, the concentration is from about 10 to about 20% by
weight.
1 ~ Monomers preferably copolymerized with the cationic monomer are
represented
by the general formula (I) includes acrylamide, methacrylamide and the
cationic
monomers represented by the general formula (II):
R_;
CH,=C -RQ
O (II)
O= -A2 -B2- N R~
11
CA 02204050 1997-04-30
wherein R,, is H or CH3; R; and R6 are each an alkyl group having 1 to 2
carbon atoms;
A~ is H or an alkyl group having 1 to 2 carbon atoms; Az is an oxygen atom or
NH; B= is
an alkyl group having 2 to 4 carbon atoms or a hydroxypropyl group and Xz is a
counter
anion.
Preferable monomers represented by the formula (II) include the ammonium salts
of dimethylaminoethyl acrylate, diethylaminoethyl acrylate,
dimethylaminopropyl
acn~lamide, diethylaminopropyl acn~lamide and dimethylhydroxypropyl acrylate,
dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate,
dimethylaminopropyl
methacnUamide, diethylaminopropyl methacrylamide and dimethylhydroxypropyl
methacrylate as well as the methylated and ethylated quaternary salts. Among
the more
1 ~ preferable cationic monomers represented by the general formula (II) are
the salts and
methylated quaternary salts of dialkylaminoethyl acrylate and
dialkylaminoethyl
methacrvlate.
The polyvalent anionic salt to be incorporated in the aqueous solution
according
to the present invention is suitably a sulfate, a phosphate or a mixture
thereof. Preferable
salts include ammonium sulfate, sodium sulfate, magnesium sulfate, aluminum
sulfate,
ammonium hydrogen phosphate. sodium hydrogenphosphate and potassium
12
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hydrogenphosphate. In the present invention, these salts may be each used as
an aqueous
solution thereof having a concentration of 15% or above.
A dispersant is present in the aqueous anionic salt solution in which the
polymerization of the above monomers occurs. The dispersant is a water-soluble
high
molecular weight cationic polymer. The dispersant is soluble in the above-
mentioned
aqueous salt solution. The dispersant is preferably used in an amount of from
1 to 10%
by weight based on the total weight of the monomers. The dispersant is
composed of 20
mole % or more of cationic monomer units represented by the formula (II).
Preferably
the residua( mole % is acrylamide or methacrylamide. The performance of the
dispersant
is not greatly affected by molecular weight. However, the molecular weight of
the
dispersant is preferably in the range of 10,000 to 10,000,000 daltons.
According to one
embodiment of the invention a multifunctional alcohol such as glycerin or
polyethylene
glycol is coexistent in the polymerization system. The deposition of the fine
particles is
smoothly carried out in the presence of these alcohols.
1 ~ For the polymerizations a usual water-soluble radical-forming agent can be
employed. but preferably water-soluble azo compounds such as 2,2'-azobis(2-
amidinopropane) hydrochloride and 2.2~-azobis(N.N'-dimethyleneisobutylamine)
hydrochloride are used.
According to one embodiment of the invention, a seed polymer is added before
the beginning of the polymerization of the above monomers for the purpose of
obtaining
a fine dispersion. The seed polymer is a water-soluble cationic polymer
insoluble in the
aqueous solution of the polyvalent anionic salt. The seed polymer is
preferably a
13
CA 02204050 1997-04-30
polymer prepared from the above monomer mixture by the process described
herein.
Nevertheless, the monomer composition of the seed polymer need not always be
equal to
that of the water-soluble cationic polymer formed during polymerization.
However, like
the water-soluble polymer formed during polymerization, the seed polymer
should
contain at least ~ mole percent of cationic monomer units represented by the
general
formula (I). According to one embodiment of the invention, the seed polymer
used in
one polymerization reaction is the water-soluble polymer prepared in a
previous reaction
which used the same monomer mixture.
ram le
The following examples are presented to describe preferred embodiments and
utilities of the invention and are not meant to limit the invention unless
otherwise stated
in the claims appended hereto. In the following examples, common terms used
throughout have the following meanings.
Microparticle A (colloidal silica)
1 ~ Dispersed silica in water with a particle size of 4 rtm.
Microparticle B
Copolymer of acrylic acid
Microparticle C (bentonite)
Hydrated suspension of powdered bentonite in water.
14
CA 02204050 1997-04-30
Dispersion Polymers
Polymer A 10 mole% DMAEA.BCQ RSV 19.6 dl/g
Polymer B 10 Mole % DMAEA.MCQ RSV 21.4 dUg
Polymer C 20 mole % DMAEA.MCQ RSV 27.6 dl/g
Latex Polymer
Polymer D 10 mole% DMAEA.MCQ RSV 19.7 dl/g
The Reduced Specific Viscosity (RSV) was measured at a concentration of
0.04% polymer in a solution of 0.13~M NaN03 solution.
Britt Jar Test
The Britt Jar Test employed in Examples 1 to 3 used a Britt CF Dynamic
Drainage Jar developed by K. W. Britt of New York State University, which
generally
consists of an upper chamber of about I liter capacity and a bottom drainage
chamber, the
chamber bein, separated by a support screen and a drainage screen. Below the
drainage
chamber is a downward extendin, flexible tube equipped with a clamp for
closure. The
upper chamber is provided with a variable speed, high torque motor equipped
with a 2-
1 ~ inch 3-bladed propeller to create controlled shear conditions in the upper
chamber. The
test w'as conducted by placing the cellulosic stock in the upper chamber and
then
subjecting the stock to the followine sequence:
15
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Time Action
0 seconds Commence shear stirring at 7~0 rpm, (add
starch, if needed).
Add the cationic polymer, increase speed to
seconds 2000 rpm.
40 Reduce shear stirring to 750 rpm.
seconds
50 Add the microparticle.
seconds
60 Open the tube clamp to commence drainage,
seconds and continue drainage for 30 seconds.
The material so drained from the Britt jar (the "filtrate") is collected and
diluted
with water to one-fourth of its initial volume. The turbidity of such diluted
filtrate,
~ measured in Formazin Turbidity Units or FTU's, is then determined. The
turbidity of
such a filtrate is inversely proportional to the papermaking retention
performance; the
lower the turbidity value, the higher is the retention of filler andlor fines.
The turbidity
values were determined using a Hach Spectrophotometer, model DR2000.
The turbidity values (in FTU) that were determined were converted to (Percent
10 Improvement) values using the formula:
Percent Improvement = 100 X (Turbidityl, - Tur6idity~lTurbidityu
where Turbidityu is the turbidity reading result for the blank for which no
polymer or
I ~ microparticle, and wherein Turbidity~ is the turbidity reading result of
the test using
polymer, or polymer and microparticle.
16
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Filtration Test
The filtration tests used in Examples 1 to 8 measured the drainage (water
removal) rate of the test stock subjected to the various chemical treatments.
A filtration
celh mounted upright on a stand, was used. The capacity of this cell is about
220
milliliters. A 200 mesh drainage screen (761rm screen with 8% opening) served
as the
filter medium. The stock was filtered by gravity. The filtrate was collected
in a cup
placed on a weighing balance below the cell. This balance was interfaced with
a
computer so that the displayed weight was recorded continuously over time. The
computer automatically recorded the change of weight over time.
The cellulosic stock was treated in the aforementioned Brittjar. The treated
stock
was transferred to the cell and filtered until completion. The rate of
filtrate collection is
an indication of the drainage performance; the higher the filtrate collection
rate, the
higher is the improvement in drainage.
1 ~ Test Stocla
Alkaline Test Stock
The cellulosic stock or slurry used in Examples 1 to 3 and 8 was comprised of
70
weight percent fiber and 30 weight percent filler, diluted to an overall
consistency of 0.5
percent with formulation water. The fiber was a 60/40 blend by weight of
bleached
hardwood Krafr and bleached softwood Krafr, separately beaten to a Canadian
Freeness
value range of from 320 to 360 C.F.S. The filler was a commercial calcium
carbonate ,
provided in dry form. The formulation water contained 60 ppm calcium hardness
(added
17
CA 02204050 1997-04-30
as CaCl2 ), 18 ppm magnesium hardness (added as MgS04) and 134 ppm bicarbonate
alkalinity ( added as NaHC03). The pH of the final thin stock was pH 7.2.
Acid Test Stock
The cellulosic stock or slurry used in Examples 4 to 5 was comprised of 93
weight percent fiber and 7 weight percent filler, diluted to an overall
consistency of 0.54
percent with formulation water. The fiber was a 50/50 blend by weight of
bleached
hardwood Kraft and bleached sofrwood Kraft, separately beaten to a Canadian
Freeness
value range of from 320 to 360 C.F.S. The fillers were clay as predispersed
kaolin and
titanium dioxide, commercially provided in dry form. The pH was adjusted to pH
4.00
using dilute sulfuric acid. following which alum (0.00% of final slurry) and
sizing agent
rosin (0.002 w~t% of final slurry) were added. The formulation water contained
60 ppm
calcium hardness (added as CaCI_), 18 ppm magnesium hardness (added as MgS04)
and
134 ppm bicarbonate alkalinity ( added as NaHC03).
Corrucated Coated Test Stock
1 ~ The stock used in Examples 6 and 7 was obtained as thick stock
(consistency of
=1.1 1 %) from a paper mill. It was a mixture of OCC, newsprint, and boxboard.
It was
diluted to an overall consistency of 0.8% with formulation water containing 60
ppm
calcium hardness (added as CaCl2 ), 18 ppm magnesium hardness (added as MgS04)
and
134 ppm bicarbonate alkalinity ( added as NaHC03). The final pH of the thin
stock was
pH 6.~. The percent ash of the thin stock was 7.3 wt%.
18
CA 02204050 1997-04-30
Example 1
Using the alkaline test stock described above, the Britt jar test, also
described
above was employed to determine the retention performances of dispersion
Polymer A in
comparison to the inverse emulsion Polymer D, with microparticle A as the
microparticle. In each test, cationic potato starch was charged to the test
stock in the
amount of 10 lb/ton of dry weight of slum solids. The various programs tested
are
shown below in Table 1. The test results are reported in Table 1 below as
diluted filtrate
turbidity values (FTU) and (Percent Improvement), as defined earlier, for each
of the
programs tested.
The drainage performance of these programs was measured for the same alkaline
furnish using the filtration test described above. In each test starch was
charged to the
1 p test stock in the amount of 10 Ib/ton of dry weight of slurry solids. The
results are shown
for each of the programs tested in Figure I as graphs of collected filtrate
weight versus
Ume.
Example 2
Using the alkaline test stock described above, the Britt jar test, also
described
above was employed to determine the retention performances of dispersion
Polymer B in
comparison to the inverse emulsion Polymer D, with microparticle A as the
microparticle. In each test, cationic potato starch was charged to the test
stock in the
19
CA 02204050 1997-04-30
amount of 10 lb/ton of dry weight of slurry solids. The various programs
tested are
shown below in Table 2. The test results are reported in Table 2 below as
diluted filtrate
turbidity values (FTU) and (Percent Improvement), as defined earlier, for each
of the
programs tested.
The drainage performance of these programs was measured for the same alkaline
furnish using the filtration test described above. In each test starch was
charged to the
test stock in the amount of 10 lb/ton of dry weight of slurry solids. The
results are shown
for each of the programs tested in Figure 2 as graphs of collected filtrate
weight versus
time.
Table I
Britt Jar Retention Tests
Alkaline Furnish
No. Polymer Polymer Microparticle Turbidity Percent
Dosage A Dosage (FTU) Improvement
Ib/ton Ib/ton
blank 0 0 39.5 -
1 A 1.6 0 289 20
2 A 1.6 2 84 77
3 D 1.6 0 291 19
4 D 1.6 2 162 5~
CA 02204050 1997-04-30
Table II
Britt Jar Retention Tests
Alkaline Furnish
No. Polymer Polymer MicroparticleTurbidity Percent
Dosage A Dosage (FTl>] Improvement
lb/ton Ib/ton
blank 0 0 359.5
1 B 1.6 0 252 30
2 B 1.6 2 74 79
3 D 1.6 0 291 19
4 D 1.6 2 162
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CA 02204050 1997-04-30
Example 3
Using the alkaline test stock described above, the Britt jar test, also
described
above was employed to determine the retention performances of dispersion
Polymer C in
comparison to the inverse emulsion Polymer D, with microparticle A as the
microparticle. In each test, cationic potato starch was charged to the test
stock in the
amount of 10 lb/ton of dry weight of slurry solids. The various programs
tested are
shown below in Table 3. The test results are reported in Table 3 below as
diluted filtrate
turbidity values (FTU) and (Percent Improvement), as defined earlier, for each
of the
programs tested.
Table III
Britt Jar Retention Tests
Alkaline Furnish
No. Polymer Polymer MicroparticleTurbidity Percent
Dosage A Dosage (FTU) Improvement
Ib/ton Ib/ton
blank 0 0 359.5
1 C L.6 0 266 26
2 C 1.6 2 120 67
3 D 1.6 0 291 19
4 D 1.6 2 162 55
Example 4
Using the acid test stock described above, the filtration test, also described
above
was employed to determine the drainage performances of dispersion Polymer A in
comparison to the inverse emulsion Polymer D, with microparticle A as the
microparticle. The results are shown for each of the programs tested in Figure
3 as
graphs of collected filtrate weight versus time.
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CA 02204050 1997-04-30
Example 5
Using the acid test stock described above, the filtration test, also described
above
was employed to determine the drainage performances of dispersion Polymer A in
comparison to the inverse emulsion Polymer D, with microparticle B as the
microparticle.
The results are shown for each of the programs tested in Figure 4 as graphs of
collected
filtrate wei2ht versus time.
Example 6
Using the corrugated coated test stock described above, the filtration test,
also
described above was employed to determine the drainage performances of
dispersion
Polymer A. with microparticle A as the microparticle. The results are shown
for each of
the programs tested in Figure 5 as graphs of collected filtrate weight versus
time.
l~ Example 7
Using the corrugated coated test stock described above, the filtration test,
also
described above was employed to determine the drainage performances of
dispersion
Polymer A, with microparticle B as the microparticfe. The results are shown
for each of
the programs tested in Figure 6 as graphs of collected filtrate weight versus
time.
Exam le
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CA 02204050 1997-04-30
Using the alkaline test stock described above, the filtration test, also
described
above was employed to determine the drainage performances of dispersion
Polymer A in
comparison to the inverse emulsion Polymer D, with microparticle C as the
microparticle.
In each test, cationic potato starch was charged to the test stock in the
amount of 10 Ib/ton
of dry weight of slurry solids. The results are shown for each of the programs
tested in
Figure 7 as graphs of collected filtrate weight versus time.
Changes can be made in the composition, operation and arrangement of the
method of the present invention described herein without departing from the
concept and
scope of the invention as defined in the following claims:
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