Note: Descriptions are shown in the official language in which they were submitted.
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COLLOIDAL BOROSILICATES AND THEIR USE IN THE
PRODUCTION OF PAPER
This is a divisional application of Canadian Patent Application Serial No.
2,304,709 filed on September 17, 1998.
Background of the Invention
1. Field of the Invention
The invention relates to a borosilicate retention aid composition and, a
method of
using the borosilicate retention aid composition in the production of paper. A
method of
making such borosilicate retention aid composition is also disclosed. The
borosilicate
materials are preferably an aqueous suspension of colloidal borosilicate. It
should be
understood that the expression "the invention" and the like encompasses the
subject
matter of both the parent and the divisional applications.
2. Backilround of the Invention
In the manufacture of paper, an aqueous cellulosic suspension or furnish is
formed
into a paper sheet. The slurry of cellulosic fiber is generally diluted to a
consistency
(percent dry weight of solids in the furnish) having a fiber content of about
4 weight
percent of fiber or less, and generally around 1.5% or less, and often below
1.0 % ahead
of the paper machine, while the finished sheet typically has less than 6
weight percent
water. Hence the dewatering and retention aspects of papermaking are extremely
important to the efficiency and cost of the manufacture.
Gravity dewatering is the preferred method of drainage because of its
relatively
low cost. After gravity drainage more expensive methods are used for
dewatering, for
instance vacuum, pressing, felt blanket blotting and pressing, evaporation and
the like. In
actual practice a combination of such methods is employed to dewater, or dry,
the sheet
to the desired water content. Since gravity drainage is both the first
dewatering method
employed and the least expensive, an improvement in the efficiency of this
drainage
process 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.
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Another aspect of paperrnaking that is extremely important to the efficiency
and cost is retention of furnish components on and within the fiber mat. The
papermaking furnish represents a system containing significant amounts of
small
particles stabilized by colloidal forces. A papermaking furnish generally
contains, in
addition to cellulosic fibers, particles ranging in size from about 5 to about
1000 nm
consisting of for example cellulosic fines, mineral fillers (employed to
increase
opacity, brightness and other paper characteristics) and other small particles
that
(Tenerally, without the inclusion of one or more retention aids, would in
significant
portion pass through the spaces (pores) betlveen the mat formed by the
cellulosic
fibers on the papermachine.
Greater retention of fines, fillers, and other components of the furnish
permits,
for a given grade of paper, a reduction in the cellulosic fiber content of
such paper. As
pulps of lower quality are employed to reduce papermaking costs, the retention
aspect
of paperrnaking becomes more important because the fines content of such lower
quality pulps is generally greater. Greater retention also decreases the
amount of such
substances lost to the whitewater and hence reduces the amount of material
wastes, the
cost of waste disposal and the adverse environmental effects therefrom. 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.
Another important characteristic of a given papermaking process is the
formation of the paper sheet produced. Formation may be 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 or
90 %, the formation parameter generally declines.
Various chemical additives have been utilized in an attempt to increase the
rate
at which water drains from the formed sheet, and to increase the amount of
fines and
filler retained on the sheet. The use of high molecular weight water soluble
polymers
was a significant improvement in the manufacture of paper. These high
molecular
weight polymers act as flocculants, forming large flocs which deposit on the
sheet.
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They also aid in the dewatering of the sheet. In order to be effective,
conventional
single and dual polymer retention and drainage programs require incorporation
of a
higher molecular weight component as part of the program. In these
conventional
programs, the high molecular weight component is added after a high shear
point in
the stock flow system leading up to the headbox of the paper machine. This is
necessary since flocs are formed primarily by the bridging mechanism and their
breakdown is largely irrev.ersible and do not re-form to any significant
extent. For this
reason, most of the retention and drainage performance of a flocculant is lost
by
feeding it before a high shear point. To their detriment, feeding high
molecular weight
polymers after the high shear point often leads to formation problems. The
feed
requirements of the high molecular weight polymers and copolymers which
provide
improved retention often lead to a compromise between retention and formation.
While successful, high molecular weight flocculant programs were improved
by the addition of so called inorganic "microparticles".
Polymer/microparticle programs have gained commercial success replacing the
use of polymer-only retention and drainage programs in many mills.
Microparticle
containing programs are defined not only by the use of a microparticle
component but
also often by the addition points of chemicals in relation to shear. In most
microparticle containing retention programs, high molecular weight polymers
are
added either before or after at least one high shear point. The inorganic
microparticulate material is then usually added to the furnish after the stock
has been
flocculated with the high molecular weight component and sheared to break down
those flocs. The microparticle addition re-flocculates the furnish, resulting
in
retention and drainage that is at least as good as that attained using the
high molecular
weight component in the conventional way (after shear), with no deleterious
impact on
formation.
One such program employed to provide an improved combination of retention
and dewatering is described in United States Pat. Nos. 4,753,710 and
4,913,775, to
Langley et al.
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In the method disclosed in Langley et aL, a high molecular weight
linear cationic polymer is added to the aqueous cellulosic papermaking
suspension
before shear is applied to the suspension, followed by the addition of
bentonite after
the shear application. Shearing is generally provided by one or more of the
cleaning,
mixing and pumping stages of the papermaking process, and. the shear breaks
down
the large flocs formed by the high molecular weight polymer into microflocs.
Further
agglomeration then ensues with the addition of the bentonite clay particles.
Other such microparticle programs are based on the use of colloidal silica as
a
microparticle in combination with cationic starch such as that described in U.
S.
Patents. No. 4,388,150 and 4,385,961, or the use of a cationic starch,
flocculant, and
silica sol combination such as that described in both U.S. Patents 5,098,520
and
5,185,062. U.S. Patent 4,643,801 claims a method for the preparation of paper
using a high
molecular weight anionic water soluble polymer, a dispersed silica, and a
cationic starch.
Although, as described above, the microparticle is typically added to the
furnish after the flocculant and after at least one shear zone, the
microparticle effect
can also be observed if the microparticle is added before the flocculant and
the shear
zone (e.g., wherein the microparticle is added before the screen and the
flocculant afler
the shear zone).
In a single polymer/microparticle retention and drainage aid program, a
flocculant, typically a cationic polymer, is the only polymer material added
along with
the microparticle. Another method of improving the flocculation of cellulosic
fines,
mineral fillers and other furnish components on the fiber mat using a
microparticle is
in combination with a dual polymer program which uses, in addition to the
microparticle, a coagulant and flocculant system. In such a system a coagulant
is first
added, for instance a low molecular weight svnthetic cationic polymer or
cationic
starch_ The coagulant may also be an inorganic coagulant such as alum or
polyaluminum chlorides. This addition can take place at one or several points
within
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the furnish make up systeni, including but not limited to the thick stock,
white water
system. or thin stock of a machine. This 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.
The coagulant treatment is followed by the addition of a flocculant. Such a
flocculant
generallv is a high molecular weight synthetic polymer which bridges the
particles
and/or agglomerates, from one surface to another, binding the particles into
larger
agglomerates. The presence of such large agglomerates in the fumish, as the
fiber mat
of the paper sheet is being formed, increases retention. The agglomerates are
filtered
out of the water onto the fiber web, whereas unagglomerated particles would,
to a
great extent, pass through such a paper web. In such a program the order of
addition of
the microparticle and flocculant can be reversed successfully.
The present invention departs from the disclosures of these patents in that a
borosilicate, preferabiv a colloidal borosilicate is utilized as the
microparticle.
Surprisingly we have found that borosilicates provide improved performance
over
other microparticle programs, and especially those using colloidal silica sols
as the
microparticle. The borosilicate microparticles of the invention allow the
production of
paper and board having improved levels of retention, formation, uniform
porosity, and
overall dewatering.
Summarv of the Invention
One aspect of the invention comprises a borosilicate retention aid
composition.
The borosilicates, preferably aqueous solutions of colloidal particles of
borosilicate,
useful in this invention have a mole ratio of boron to silicon of from 1:1000
to 100:1
and generally from 1:100 to 2:5. Preferably the mole ratio of sodium to
silicon in the
borosilicate materials of this invention ranges from 0.006 to 1.04 and even
more
preferably ranges between 0.01 to 0.7. A further aspect of the invention
comprises a
papermaking system which comprises the steps of adding to a papermaking fumish
from about 0.00005 to about 1.25% by weight, based on the weight of the dry
fiber in
the fumish, of a borosilicate. In an alternative embodiment, a nonionic,
cationic, or
anionic polymeric flocculant is added to the furnish either before or after
addition of
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the borosilicate in an amount of from about 0.001 to about 0.50 % by weight
based on
the dry weight of fiber in the furnish. An alternative is the addition of
cationic starch
or guar gum in place of or in addition to a polymeric flocculant to the
furnish either
before or after addition of the borosilicate in an amount of from about 0.005
to about
5.0 % by weight based on the dry weight of fiber in the furnish. Another
alternative is
the addition of a coagulant to the furnish in an amount ranging from 0.005 to
1.25%
by weight of the dry weight of the fiber in the furnish. The flocculation of
components
of the papermaking furnish is increased when the borosilicate is added alone
or in
combination with a conventional polymeric flocculant, alone or in combination
with a
coagulant.
According to a first aspect of the invention there is provided a method for
the
manufacture of a cellulosic sheet which comprises a) forming a cellulosic
furnish
containing from 0.01 to 1.5% by weight cellulosic fiber; b) adding to the
furnish from
about 0.00005 to about 1.25% by weight, based on the dry weight of fiber in
the
furnish, of a borosilicate having a mole ratio of boron to silicon of from
about 1:1000
to about 100:1, a mole ratio of alkali metal to silicon of from about 6:1000
to about
1.04:1, a particle size of from about 1 to 2000 nm; and a surface area of from
about 15
to 3000 m2 /g.; and, from about 0.001 to about 0.5% by weight, based on the
dry
weight of fiber in the furnish of a substantially water soluble polymeric
flocculant
having a molecular weight greater than 500,000 daltons; and then, c)
dewatering said
furnish to obtain a cellulosic sheet.
According to a second aspect of the invention there is provided a method for
the preparation of a colloidal borosilicate which comprises the steps of
contacting a
dilute aqueous solution of an alkali metal silicate with a cation exchange
resin to
produce a silicic acid; forming a heel by mixing together a dilute aqueous
solution of
an alkali metal borate with an alkali metal hydroxide to form an aqueous
solution
containing 0.01 to 30 percent B2 03, having a pH of from 7 to 10.5; adding the
silicic
acid to the aqueous solution with agitation; and then recovering an aqueous
colloidal
borosilicate.
According to a third aspect of the invention there is provided a method for
flocculating the components of a paper mill furnish in a papermaking system
into a
cellulosic sheet comprising: adding to a papermaking furnish from about
0.00005 to
about 1_25% by weight, based on the dry weight of fiber in the furnish, of a
borosilicate
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having a mole ratio of boron to silicon of from about 1:1000 to about 100:1, a
mole
ratio of alkali metal to silicon of from about 6:1000 to about 1.04:1, a
particle size of
from about l to 2000 nm; and a surface area of from about 15 to 3000 m2 /g;
and from
about 0.001 to about 0.5% by weight, based on the dry weight of fiber in the
fumish
of a substantially water soluble polymeric flocculent having a molecular
weight
greater than 500,000 Daltons; subjecting the furnish to papermaking
conditions; and
recovering a cellulosic sheet.
According to a fourth aspect of the invention there is provided a method for
increasing drainage rate of water from the solid components of a paper mill
furnish
comprising adding to the paper mill furnish from about 0.00005 to about 1.25%
by
weight, based on the dry weight of fiber in the furnish, of a borosilicate
having a mole
ratio of boron to silicon of from about 1:1000 to about 100:1, a mole ratio of
alkali
metal to silicon of from about 6:1000 to about 1.04:1, a particle size of from
about I
to 2000 nm; and a surface area of from about 15 to 3000 m 2 /g, and from about
0.005
to 5.0% by weight, based on fiber in the furnish, of a cationic starch; and
then
flocculating the furnish; whereby the drainage rate of water from the paper
mill
fumish is increased.
According to a fifth aspect of the invention there is provided 52. A Method
for
increasing retention of fines and fillers on a cellulosic sheet formed from a
papermaking furnish subjected to papermaking conditions comprising the steps
of
adding to the papermaking furnish from about 0.00005 to about 1.25% by weight,
based on the dry weight of fiber in the furnish, of a borosilicate having a
mole ratio of
boron to silicon of from about 1:1000 to about 100:1, a mole ratio of alkali
metal to
silicon of from about 6:1000 to about 1.04:1, a particle size of from about I
to 2000
nm; and a surface area of from about 15 to 3000 m2 /g; and from about 0.001 to
about
0.5% by weight, based on the dry weight of fiber in the furnish of a
substantially
water soluble polymeric flocculant having a molecular weight greater than
500,000
Daltons; and then subjecting the fumish to papermaking conditions; and
recovering a
cellulosic sheet, whereby the retention of fines and fillers on said sheet and
the rate of
drainage of liquid from said sheet is increased.
According to a sixth aspect of the invention there is provided an aqueous
colloid comprising amorphous borosilicate particles, wherein said amorphous
borosilicate
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particles are not borosilicate glass and wherein said amorphous borosilicate
particles
have a mole ratio of alkali metal to silicon of from about 6:1000 to about
1.04:1.
The borosilicate products described in the present application are amorphous.
Their amorphous structure is evident from X-Ray diffraction analysis.
By the addition of the borosilicate particles of this invention to a
papermaking
furnish or slurry prior to sheet formation, improved sheet properties may be
obtained. As
used herein, the term furnish or slurry is meant as a suspension of cellulosic
fibers used
to form a cellulosic sheet. The sheet may be a fine paper (which as used
herein includes
virgin-fiber-based as well as recycle-fiber based material), board (which as
used herein
includes recycle-fiber based test liner and corrugating medium as well as
virgin-fiber
based materials), and newsprint (which as used herein includes magazine
furnishes as
well as both virgin fiber and recycle-fiber based), or other cellulosic
material. The final
sheet may contain in addition to a cellulosic fiber mat, fillers, pigments,
brighteners,
sizing agents, and other materials used in the production of the numerous
grades of
cellulosic mats commonly referred to as paper or board.
Brief Description of the Drawings
Figure 1 shows X-ray scanning diffraction data for amorphous borosilicate
particles from a colloid.
Figure 2 shows X-ray scanning diffraction data for a quartz material.
Detailed Description of the Invention
The invention comprises a retention and drainage aid composition comprising
a borosilicate (preferably a colloidal borosilicate) having a mole ratio of
boron to
silicon ranging from about 1: 100 to about 2:5. In a preferred embodiment of
the
invention, the borosilicate is characterized as having a mole ratio of sodium
to silicon
ranging from about 6:1000 to 1.04:1. The microparticle retention aid is
preferably a
colloid of borosilicate having a chemistry similar to than of borosilicate
glass. The
borosilicate is preferably used in the form of an aqueous colloid. This
colloid is
generally prepared by reacting an alkali metal salt of a boron containing
compound
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with silicic acid under conditions resulting in the formation of a colloid.
The
borosilicate particles useful in this invention may have a particle size over
a wide
range, for example from inm (nanometer) to 2 microns (2000nm), and preferably
from inni to 1 micron. When a colloidal borosilicate is utilized the particle
size will
generally be in the railge of from I mn to 200nm and preferably from I to
80nm, and
most preferably 20-80nn1. The surface area of the borosilicate particles
useful in this
invention can likewise vary over a wide range. Generally as particle size
decreases,
surface area will increase. The surface area should be in the range of 15 to
3000m2/g
and preferably 50 to 3000m2/g. When the preferred colloidal borosilicate
particles of
the invention are utilized the surface area will generally be in the range of
250 to
3000m2 /g and preferably from 700 to 3000m2/g.
The preferred colloidal borosilicate materials useful in this invention are
generally prepared by first preparing silicic acid. This may be advantageously
accomplished by contacting an alkali metal silicate solution, preferably a
dilute
solution of the alkali metal silicate with a commercial cation exchange resin,
preferably a so called strong acid resin, in the hydrogen form and recovering
a dilute
solution of silicic acid. The silicic acid may then be added, with agitation
to a dilute
solution of an alkali metal borate at a pH of from 6-14, and a colloidal
borosilicate
product suspended in water is recovered. Altematively, the alkali metal borate
and the
silicic acid may be added simultaneously to prepare suitable materials. In the
usual
practice of this invention, the concentration of the silicic acid solution
utilized is
generally from 3 to 8 percent by weight SiO,, and preferably 5 to 7 percent by
weight
SiO,. The weight percent of the borate solution utilized is generally 0.01 to
30 and
preferably 0.4 to 20 weight percent as B203_ The borate salt utilized may
range over a
wide variety of compounds. Commercial borax, sodium tetraborate decahydrate,
or
sodium tetraborate pentahydrate are the preferred material in the practice of
this
invention because of the ready availability of these materials and their low
cost. Other
water soluble borate materials may be utilized. We believe that any soluble
alkali
metal borate salt may be employed in the practice of this invention. The
preparation
of the colloidal borosilicate material of this invention may be accomplished
with or
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without pH adjustment. It is sometimes advisable to conduct the reaction at a
pH of
7.5 to 10.5 through the addition of an appropriate alkali metal hydroxide,
preferably
sodium hydroxide, to the reaction mixture. Best results have been obtained in
the pH
range of 8 to 9.5 although as will be appreciated, the synthesis procedures
for the
borosilicate compositions of this invention are still being optimized. We
believe that
agitation, rate of addition, and other parameters are non-critical to the
formation of the
colloidal borosilicate compositions of the invention. Other methods of
preparing the
colloidal borosilicates of this invention may also be utilized. These methods
could
encompass preparing the colloidal borosilicate as above and spray drying the
particles
followed by grinding, or other methods which would yield a borosilicate
material
meeting the parameters set forth above.
The invention further comprises a method of improving the production of
paper which comprises the step of adding to a paper mill fumish from about
0.00005
to about 1.25% by weight based on the dry weight of fiber in the slurry or
furnish of a
borosilicate, preferably a colloidal borosilicate. In an alternative
embodiment, a
nonionic, cationic or anionic polymeric flocculant may be added to the furnish
either
before or after the addition of the borosilicate in an amount of from about
0.001 to
about 0.5% by weight based on dry weight of fiber in the fumish. A cationic
starch
may alternatively be added to the furnish in place of, or in addition to the
synthetic
polymer flocculant in an amount of from about 0.005 to about 5.0% by weight
based
on the dry weight of fiber in the furnish. More preferably, the starch is
added in an
amount of from about 0.05 to about 1.5% by weight based on the dry weight of
fiber
in the furnish. In yet another embodiment, a coagulant may be added to the
furnish in
place of, or in addition to, the flocculant and/or the starch in an amount of
from about
0.005 to about 1.25% by weight based on the dry weigllt of fiber in the
papermaking
furnish. Preferably the coagulant is added in an amount of from about 0.025 to
about
0.5% by Nveight based on the dry weight of fiber in the furnish.
Tliis invention is also directed to a.method for increasing retention and
drainage of a papermaking fumish on a papermaking machine which comprises the
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steps of adding to a papermaking fumish from about 0.00005 to about 1.25 % by
weight based on the dry weight of fiber in the furnish of a borosilicate
particle,
preferably a colloidal borosilicate. The borosilicate may be added to the
papermaking
fumish along with a nonionic, cationic or anionic polymeric flocculant. The
flocculant may be added either before or after the borosilicate in an amount
of from
about 0.001 to about 0.5% by weight based on the dry weight of fiber in the
furnish.
Starch may alternatively be added to the furnish in place of or in addition to
the
flocculant in an amount of from about 0.005 to about 5.0% by weight based on
dry
weight of fiber in the furnish. If starch is utilized it is preferably a
cationic starch.
When used, the starch is preferably_added in an amount of from about 0.05 to
about
1.5% by weight based on the dry weight of fiber in the fumish. In yet another
alternative, a coagulant may be added to the fumish in place of, or in
addition to, the
flocculant and/or the starch in an amount of from about 0.005 to about 1.25%
by
weight based on the dry weight of fiber in the furnish. Preferably, the
coagulant is
added in an amount of from about 0.025 to about 0.5% by weight based on the
dry
weight of fiber in the furnish.
The dosage of the polymeric flocculant in any of the above embodiments is
preferably from 0.005 to about 0.2 weight percent based on the dry weight of
fiber in
the furnish. The dosage of the borosilicate is preferably from about 0.005 to
about
0.25 percent by weight based on the weight of dry fiber in the furnish, and
most
preferably from about 0.005 to about 0.15% by weight of fiber in the furnish.
It should be pointed out that since this invention is applicable to a broad
range
of paper grades and furnishes the percentages given above may occasionally
vary. It
is within the spirit and intent of the invention that variance can be made
from the
percentages given above without departing from the invention, and these
percentage
values are given only as guidance to one skilled in the art.
In any of the above embodiments, bentonite, talc, synthetic clays, hectorite,
kaolin, or mixtures thereof may also be added anywhere in the papermaking
systeni
prior to sheet formation. The preferred addition point is the thick stock pulp
before
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dilution with wllitewater. This application results in increased cleanliness
of the
papermaking operation which otherwise experiences-hydrophobic deposition
affecting
both the productivity and the quality of paper.
In addition, any of the above embodiments may be applied to papennaking
furnish selected from the group consisting of fine paper, (which as used
herein
includes virgin fiber based as well as recycle-fiber based materials), board
(which as
used herein includes recycle-fiber based test liner and corrugating medium as
well as
virgin-fiber based materials),and newsprint (which as used herein includes
magazine
furnishes as well as both virgin fiber and recycle-fiber based), or other
cellulosic
material. These furnishes include those that are wood-containin--, wood-free,
virgin,
bleached recycled, unbleached recycled, and mixtures thereof.
Paper or paperboard is generally made from a suspension or furnish of
cellulosic material in an aqueous medium, which furnish is subjected to one or
more
shear stages, in which such stages generally are a cleaning stage, a mixing
stage and a
pumping stage, and thereafter the suspension is drained to form a sheet, which
sheet is
then dried to the desired, and generally low, water concentration. The
borosilicate
materials of the invention may be added to the furnish before or after a shear
stage.
In addition to the retention and drainage aid applications described above,
the
borosilicate materials may be used in conjunction with standard cationic wet
strength
resins to improve the wet strength of cellulosic sheet so treated. When
utilized in this
manner the borosilicate is added to the furnish prior to placement of the
fumish,
containing the wet strength resin, on a papermachine. The borosilicate is
generally
utilized at the levels set forth above.
The borosilicate of this invention has been found to significantly enhance the
performance of synthetic polymeric flocculants and retention aids, and starch
in the
paperrnaking process. Further, the borosilicate materials are believed to have
utility as
additives in solids/liquids separation processes such as water pretreatment,
and in
wastewater treatment applications. The borosilicates in addition to enhancing
drainage and retention in newsprint, fine paper, board and other paper grades,
may
also find utility in pitch and stickies control in papermaking, pulp
dewatering in the
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production of dry-lap pulp, saveall and clarifier applications in pulp and
paper mills,
water clarification, dissolved air flotation and sludge dewatering. The
compositions of
this invention may also find utility in solid/liquid separation or emulsion
breaking.
Examples of such applications are municipal sludge dewatering 'the
clarification and
dewatering of aqueous mineral slurries, refinery emulsion breaking and the
like. The
enhanced performance seen utilizing the borosilicate particles of this
invention in
combination with synthetic polymers and or starch includes higher retention,
improved drainage and improved solids/liquids separation, and often a
reduction in the
amount of polymer or starch used to achieve the desired effect.
Microparticle retention programs are based on the restoration of the
originally
formed flocs broken by shear. In such applications, the flocculant is added
before at
least one high shear point, followed by the addition of microparticle just
before the
headbox. Typically, a flocculant will be added before the pressure screens,
followed
by the addition of microparticle after the screens. However a method wherein
this
order may be reversed is contemplated herein. Secondary flocs formed by the
addition
of microparticles result in increased retention and drainage without
detrimentally
affecting formation of the sheet. This allows increased filler content in the
sheet,
eliminates two-sidedness of the sheet, and increases drainage and speed of the
machine in paper manufacturing.
The use of a slight excess of polymeric flocculant and/or coagulant is
believed
necessary to ensure that the subsequent shearing results in the formation of
microflocs
which contain or carry sufficient polymer to render at least parts of their
surfaces
positively charged, although it is not necessary to render the whole furnish
positively
charged_ Thus the zeta potential of the furnish, after the addition of the
polymer and
after the shear stage, may be cationic or anionic.
Shear may be provided by a device in the apparatus used for other purposes,
such as a mixing pump, fan pump or centriscreen, or one may insert into the
apparatus
a shear mixer or other shear stage for the purpose of providing shear, and
preferably a
liigh degree of shear, subsequent to the addition of the polymer.
CA 02509271 1998-09-17
WO 99/16708 PCT/US98/1 IM9
12
The flocculants used in the application of this invention are high molecular
weight water soluble or dispersible polymers which may have a cationic or
anionic
charge. Nonionic high molecular weight polymers may also be utilized. These
polymers may be completely soluble in the papermaking system, or alternatively
may
be readily dispersible. They may have a branched or crosslinked structure
provided
that they do not form objectionable "fish eyes", so called globs of
undissolved
polymer on the finished paper. Polymers of these types are readily available
from a
vanety of commercial sources. They are available as dry solids, aqueous
solutions,
water-in-oil emulsions which when added to water allow the polymer contained
therein to rapidly solubilize, or as dispersions of the water soluble or
dispersible
polymer in aqueous brine solutions. The form of the high molecular weight
flocculant
used herein is not deemed to be critical so long as the polymer is soluble or
dispersible
in the furnish.
As stated above, the polymers may be cationic, anionic, or nonionic. Cationic
polymer flocculants useful herein are generally high molecular vinyl addition
polymers which incorporate a cationic functional group. These polymers are
generally
homopolymers of water soluble cationic vinyl monomers, or may be copolymers of
a
water soluble cationic vinyl monomer with a nonionic monomer such as
acrylamide or
methacrylamide. The polymers may contain only one cationic vinyl monomer, or
may
contain more than one cationic vinyl monomer. Alternatively, certain polymers
may
be modified or derivatized after polymerization such as polyacrylamide by the
mannich reaction to produce a cationic vinyl polymer useful in the invention.
The
polymers may liave been prepared from as little as I mole percent cationic
monomer
to 100 mole percent cationic monomer, or from a cationically modified
functional
group on a post polymerization modified polymer. Most often the cationic
flocculants
will have at least 5 mole percent of cationic vinyl monomer or functional
group, and
most preferably, at least 10 weight percent of cationic vinyl monomer or
functional
group.
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WO 99116708 PCT/US98/19339
13
Suitable cationic vinyl monomers useful in making the cationically charged
vinyl addition copolymers and homopolymers of this invention will be well
known to
those skilled in the art. These materials include: dimethylaminoethyl
methacrylate
(DMAEM), dimethylaminoethyl acrylate (DMAEA), diethylaminoethyl acrylate
(DEAEA), diethylaminoethyl methacrylate (DEAEM) or their quaternary ammonium
forms made with dimethyl sulfate or methyl chloride, mannich reaction modified
polyacrylamides, diallylcyclohexylamine hydrochloride (DACHA HCI),
diallyldimethylammonium chloride (DADMAC),
methacrylamidopropyltrimethylammonium chloride (MAPTAC) and ally] amine
(ALA). Cationized starch may also be used as a flocculant herein. The
flocculant
selected may be a mixture of those stated above, or a mixture of those stated
above
with a cationic starch. Those skilled in the art of cationic polymer based
retention
programs will readily appreciate that the selection of a particular polymer is
furnish,
filler, grade, and water quality dependent.
High molecular weight anionic flocculants which may be useful in this
invention are preferably water-soluble or dispersible vinyl polymers
containing I mole
percent or more of a monomer having an anionic charge. Accordingly, these
polymers may be homopolymers or water soluble anionically charged vinyl
monomers, or copolymers of these monomers with for instance non-ionic monomers
such as acrylamide or methacrylamide. Examples of suitable anionic monomers
include acrylic acid, methacrylamide 2-acrylamido-2-methylpropane sulfonate
(AMPS) and mixture thereof as well as their corresponding water soluble or
dispersible alkali metal and ammonium salts. The anionic high molecular weight
polymers useful in tllis invention may also be either hydrolyzed acrylamide
polymers
or copolymers of acrylamide or its hoinologues, such as methacrylamide, with
acrylic
acid or its homologues, such as methacrylic acid, or with polymers of such
vinyl
monomers as maleic acid, itaconic acid, vinyl sulfonic acid, or other
sulfonate
containing monomers. Anionic polymers may contain sulfonate or phosphonate
functional groups or mixtures thereof, and may be prepared by derivatizing
polyacrylamide or polymethacrylamide polymers or copolyniers. The most
preferred
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high molecular weight anionic flocculants are acrylic acid/acrylamide
copolymers, and
sulfonate containing polymers such as those prepared by the polymerization of
such
monomers as 2-acrylamide-2-methylpropane sulfonate, acrylamido methane
sulfonate,
acrylamido ethane sulfonate and 2-hydroxy-3-acrylamide propane sulfonate with
acrylamide or otlier non-ionic vinyl monomer. When used herein the polymers
and
copolymers of the anionic vinyl monomer may contain as little as I mole
percent of
the anionically charged monomer, and preferably at least 10 mole percent of
the
anionic monomer. Again, the choice of the use of a particular anionic polymer
will be
dependent upon furnish, filler, water quality, paper grade, and the like.
While most microparticle programs perform well with only a high molecular
weight cationic flocculant, we have seen suiprising effects using the
borosilicate
particles of the invention with high molecular weight anionic water soluble
flocculants
with the addition of a cationic coagulant.
Nonionic flocculants useful in this invention may be selected from the group
consisting of polyethylene oxide and poly(meth)acrylamide. In addition to the
above,
it may be advantageous to utilize so called amphoteric water soluble polymers
in
certain cases. These polymers carry both a cationic and an anionic charge in
the same
polymer chain.
The nonionic, cationic and anionic vinyl polymer flocculants useful herein
will
generally have a molecular weight of at least 500,000 daltons, and preferably
molecular weights of 1,000,000 daltons and higher. Water soluble and/or
dispersible
flocculants useful herein may have a molecular weight of 5,000,000, or higher,
for
instance in the range of from 10 to 30 million or higher. The polymers of the
invention
may be entirely water soluble when applied to the system, or may be slightly
branched
(two-dimensional) or slightly cross linked (three dimensional) so long as the
polymers
are dispersible in water. The use of polymers which are entirely water soluble
are
preferred, but dispersible polymers, such as those described in WO 97/16598,
may be
employed. Polymers useful may be substantially linear as such term is defined
in
Langley et. al_, U.S. Patent 4,753,710. The upper limit for molecular weight
is
CA 02509271 1998-09-17
governed by the solubility or dispersiblity of the resulting product in the
papermaking
filmish.
Cationic or amphoteric starches useful in the application of this invention
are
generally described in U.S. Patent 4,385,961. Cationic starch materials are
generally selected from the group consisting of naturally occurring polymers
based on
carbohydrates such as guar gum and starch. The cationic starch materials
believed to
be most useful in the practice of this invention include starch materials
derived frorn
wheat, potato and rice. These materials may in turn be reacted to substitute
ammonium groups onto the starch backbone, or cationize in accordance with the
process suggested by Dondeyne et al, in WO 96/30591. In general starches
useful in
this invention have a degree of substitution (d_s.) of ammonium groups within
the
starch molecule between about 0.01 and 0.05. The d_s. is obtained by reacting
the
base starch with either 3-cliloro-2-hydroxypropyl-trimethylammonium chloride
or 2,3-
epoxypropyl-trimethylammonium chloride to obtain the cationized starch. As
will be
appreciated it is beyond the scope and intent of this invention to describe
means for
the cationizing of starch materials and these modified starch materials are
well known
and are readily available from a variety of commercial sources.
Various characteristics of the cellulosic furnish, such as pH, hardness, ionic
strength and cationic demand, may affect the performance of a flocculant in a
given
application. The choice of flocculant involves consideration of the type of
charge,
charge density, niolecular weight and type of monomers and is particularly
dependent
upon the water chemistry of the furnish being treated.
Other additives may be charged to the cellulosic furnish Nvithout any
substantial interference with the activity of the present invention. Such
other additives
include for instance sizing agents, such as alum and rosin, pitch control
agents,
extenders, bioeides and the like. The cellulosic furnish to which the
retention aid
program of the invention is added may also contain pigments and or fillers
such as
titanium dioxide, precipitated and/or ground calcium carbonate, or other
mineral or
organic fillers. It may be possible, and it is within the spirit of the
invention that the
CA 02509271 1998-09-17
16
instant invention may be combined with other so called microparticle programs
such
as bentonite, kaolin, and silica sols. However data demonstrated herein shows
that the
particles of the subject invention outperform these materials, and the
combination
thereof may yield a performance level less than either of the materials by
themselves.
Nevertheless, when papermakers change grades or furnishes it is possible that
in
certain situations the combination of the borosilicate materials of the
invention with
other microparticles may be practical and desirable.
The borosilicate microparticles of the invention may also be used in
combination with a coagulant according to the teachings of Sofia et. al., U.S.
Patent
4,795,531. Sofia teaches a microparticle program in which a microparticle is
utilized in the presence of a cationic coagulant and a high molecular weight
charged
flocculant.
The cationic coagulant materials which may find use in this aspect of the
invention include well known conunercially available low-to mid molecular
weight
water soluble polyalkylenepolyamines including those prepared by the reaction
of an
alkylene polyamine with a difunctional alkyl halide. Matenals of this type
include
condensation polymers prepared from the reaction of ethylenedichloride and
ammonia, ethylene dichloride, ammonia and a secondary amine such as dimethyl
amine, epichlorohydrin-dimethylamine, epichlorohydrin-dimethylamine-ammonia,
polyethyleneimines, and the like. Also useful will be low molecular weight
solution
polymers and copolymers of vinyl monomers such as diallyldiinethylammonium
halides, especially diallyldimethylammonium chloride,
dialkylaminoalkylacrylates,
dialky-laminoalkylacrylate quaternaries, and the like where `alkyl' is meant
to
designate agroup having 1-4, and preferably 1-2 carbon atoms. Preferably
`alkyl' is
methyl. These monomers are exemplified by such materials as dimethylami oethyl
acrylate, dimethyl-aminoethyl methacrylate and their water-soluble quatemary
ammonium salts. In certain cases cationic starch may be employed as the
coagulant.
Inorganic coagulants, e.g., alum and polyaluminum chloride, may also be used
in this
invention. The usage rate of inorganic coagulants is typically from 0_05 to
2.veight
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WO 99/16708 PCT/US98/19339
17
percent based on the dry weight of fiber in the furnish. The use of a
coagulant with
the borosilicate microparticles of this invention is optional.
The present method is applicable to all grades and types of paper products
that
contain the fillers described herein, and further applicable for use on all
types of pulps
including, without limitation, chemical pulps, including sulfate and sulfite
pulps from
both hardwood and softwood, thermo-mechanical pulps, mechanical pulps and
groundwood pulps.
The amount of any mineral filler used in the papermaking process, generally
employed in a papermaking stock is from about 10 to about 30 parts by weight
of the
filler per hundred parts by weight of dry fiber in the furnish, but the amount
of such
filler mav at times be as low as about 5, or even 0, parts by weight, and as
high as
about 40 or even 50 parts by weight, same basis.
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.
Example 1-23
Each of the Examples shown in Table I below was prepared using the
following general procedure and varying the relative amounts of reagents.
Silicic acid was prepared following the general teaching of Bechtold et al.,
U.S. 2.574,902. A commercially available sodium silicate available from
OxyChem,
Dallas, Texas having a silicon dioxide content of about 29% by weight and a
sodium
oxide content of about 9% by weight was diluted with deionized water to a
silicon
dioxide concentration of 8-9% by weight. A cationic exchange resin such as
Dowex
HGR-W2H or Monosphere 650C, both available from Dow Chemical Conipany,
Midland, Michigan was regenerated to the H-form via treatment with mineral
acid
following well established procedures. The resin was rinsed following
regeneration
with deionized water to insure complete removal of excess regenerant. The
dilute
silicate solution was then passed througli a column of the regenerated waslied
resin.
The resultant silicic acid was collected.
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18
Simultaneously, an appropriate amount of borax solution (reagent grade
sodium tetraborate decahydrate) was combined with an appropriate amount of
aqueous
sodium hydroxide to form a "heel" for the reaction. Optionally, water may be
added
to the heel to insure adequate volume during the early stages of formation.
Freshly prepared silicic acid was then added to the "heel" with agitation at
room temperature. Agitation was continued for 60 minutes after complete
addition of
the silicic acid. The resulting colloidal borosilicate may be used
immediately, or
stored for later use. The table below gives amounts of silicic acid, sodium
hydroxide,
and sodium tetraborate decahydrate (borax) as well as pH.
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19
Table I
Colloidal Borosilicates
Amts Used Molar Ratio Final
Example Borax NaOH Acid Sol B/Si Na/Si pH
I 0.025M(5OmL) 0.1M(18.3mL) 130mL of 0.042 0.037 8.5
1.032g/mL
2 0.025M(50mL) 0.1M(18.5mL) 140mL of 0.028 0.025 8.0
l .046g/mL
3- 0.025M(5OmL) 0.1M(18.5mL) 140mL of 0.039 0.034 8.0
1.032g/mL
4 0.025M(5OmL) 0.1M(22.7g) 140mL of 0.028 0.027 8.5
1.045 g/mL
0.025M(5OmL) O.IM(24.3g) 140mL of 0.029 0.029 9.4
1.043g/mL
6 O.IM(50mL) 1.OM(9.7mL) 140mL of 0.117 0.116 9.4
1.043g/mL
7 0.1 M(50mL) 1 AM(9.7mL) 144mL of 0.109 0.107 9.2
1.046g/mL
8 0.IM(27.6mL) 1.OM(10.9mL) 140mL of 0.063 0.062 8.7
1.046g/mL
9 --- --- 249g of 0 0.208 -
l .047g/mL
0.1M(SOmL) 1.OM(9.7-) 70mL of 0.223 0.220 9.5
1.045g/mL
1] 0.1M(50mL) 1.OM(9.7g) 70mL of 0.223 0.220 9.5
] .045g/mL
12 0.1 M(50mL) I.OM(9.7g) I O5mL of 0:149 0.146 9.2
1.045 e/mL
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WO 99/16708 PCT/US98/19339
TABLE I (Continued)
13 0.1M(446mL) 4.57mL of 1343mL of 0.117 0.115 9.1
50wt% NaOH 1.040g/mL
14 0.1 M(223mL) 2.39mL of 1307mL of 0.063 0.062 8.5
50wt% NaOH 1.040g/mL
15 0.1 M(50mL) 1.OM(24.3mL) 150mL of 0.117 0.201 9.9
1.040g/mL
16 0.1M(IOOmL) 2.OmL of 1OOmL of 0.352 0.510 10.6
50wt% NaOH 1.040g/mL
17 0.1 M(1 OOmL) 2.OmL of SOmL of 0.704 1=.02 11.1
50wt% NaOH 1.040g/mL
18 0.1M(17mL) 2.OmL of 150mL of 0.039 0.242 11.0
50wt% NaOH I .040g/mL
19 0.I M(50mL) 2.OmL of 150mL of 0.117 0.281 10.7
50wt% NaOH 1.040g/m.L
20 0.1 M(500mL) 12.81 mL of I 500mL of 0.117 0.202 10.1
50wt% NaOH 1.040g/mL
21 0.1M(500mL) 12.81mL of 1500mL of 0.117 0.202 10.1
50wt ,o NaOH 1.040g/mL
22 0.1M(50mL) I.OM(24.3mL) 150mL of 0.117 0.201 10.1
1.040g/mL
23 0.1M(50mL) 1.OM(9.7g) 150mL of 0.117 0.116 8.9
1.040g/mL
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21
The commercially available compounds defined in Table II below are used
throughout the following Examples. Unless otherwise indicated, all are
available from
Nalco Cliemical Company, One Nalco Center, Naperville, Illinois 60563-1198..
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22
Table II
Product Description
Nalco 8671 A commercially available colloidal silica. Tliis material has an
average particle size of 4nm, a surface area of 750 ni `'Ig, and about
15% by weight Si02
Nalco& 74907 A commercially avaiiable colloidal Silica having an average
particle size of 7nm, a surface area of 372m2Jg, and containing
about 15% by weight as Si02
Polymer "A" A commercially available copolymer having a molecular weight
greater than 1 million daltons containing approxinlately 10 mole
percent of dimethylaminoethylaerylate, metliyl chloride quatemary
and 90 mole percent acrylamide copolymer containing
approximately 26 percent by weight solids.
Solvitose N A cationized potato starch which is cold water soluble.
Polymer "B" A commercially available cationic copolymer flocculant having a
molecular weight greater than 1 million daltons containing
approximately 10 mole percent copolymer of
dimethylaminoethylacrylate benzy] chloride quatemary and 90
mole percent acrylamide copolymer.
Polymer "C" A commercially available epichlorohydrin-dimethylamine
condensation polymer containing about 45 weight percent
polymer.
Polymer "G" A commercially available high molecular weight copolymer
containing approximately 10 mole percent
dimethylaminoethylmethacrylate and 90 mole percent acrylamide.
Polymer "D" A commercially available copolymer having a molecular weight
greater than I million daltons containing approximately 30 mole
percent sodium acrylate and 70 mole percent acrylamide.
Polymer "E" A commercially available copolymer flocculant having a
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WO 99/16708 PCT/US98/19339
23
molecular weight greater than I million daltons containing
approximately 17 mole percent dimethylaminoethyl acrylate and
83 mole percent acrylamide.
Polymer "F" A commercially available copolymer flocculant having a
molecular weight greater than 1 million daltons containing
approximately 10 mole percent of dimethylaminoethylacylate-
methylchloride quaternary and 90 mole percent acrylamide.
BMA 0 a colloidal silica sol available from Eka Nobel, Surte, Sweden
BMA 670 colloidal silica sol available from Eka Nobel, Surte, Sweden
BMA 780 colloidal aluminum coated silica sol available from Eka Nobel,
Surte, Sweden
The following describes the preparation of Example 9 appearing in Table I.
A control was prepared for comparison purposes. This amounts to carrying out
the
synthesis without borax in the heel. A colloidal silica was prepared by taking
9.68g of
a cominercially available sodium silicate and diluting with 22g of water. The
mixture
was agitated with a magnetic stir bar and brought to room temperature, i.e.,
25 C.
Where upon, silicic acid, 249g with a specific gravity of 1.047, was added
over a 40
minute period. Once all of the silicic acid was added to the reaction mixture,
agitation
continued for an additional hour. The colloidal silica formed contained 8.26%
by
weight SiOZ.
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Table II1
ProRer _ Comparisons
Sample Id. S.A. (m-/g) S-Value DLS Dia. (nm)
8671 700 63.5 12_6
BMA 0 65.7
BMA 670 489 32.6 15.4
BMA 780 435 21.6 145
Example 13 1210 24.2 56.2
Example 8 1052 37.1 61.1
ACS42 619 98 4.5
ACS5a 545 47 13
ACS6a 500 31 17
Sample 1 50 4.6
Sample 2 37 13.3
Sample 3 31 16.5
Example 20 35.6 58.5
JReference: Nordic Pulp and Paper, 11 l(1996), 15.
bReference: Colloids and Surfaces A, 118. (1996), 89.
Definition: S.A. = Surface Area as determined via method described below.
DLS = Dynamic Light Scattering is a method used to determine average
particle size descr-bed below.
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NO 99/36708 PCT/US98/19339
Example 24 (blend of colloidal silica sol and borax)
A"simple blend" control was prepared by mixing a conunercially available
colloidal silica and borax. A. mixture was prepared at room temperature
consisting of
50g of 0. ] M borax solution, 92.3g of water, and 82g of Nalco 8671. The pH of
the
solution was adjusted with concentrated hydrochloric acid to 9.5. The boron to
silicon
molar ratio was 0.098, while sodium to silicon molar ratio was 0.049.
Example 25 (Ex. 3 ofU.S. Patent No. 4,954,220)
An anionic polysilicate microgel, as described in U.S. Patent No. 4,954,220 by
Rushmere, Example 3 was tested. The purpose of the example within the subject
patent was to demonstrate that certain ionic salts induce the formation of
polysilicic
acid microgel. These salts are chosen so as to adjust the pH of a sodium
silicate
solution into the unstable, pH range. A 5% by weight borax solution was
prepared
from 5g of sodium orthoborate=decaliydrate and 95g of water. A 3.75% sodium
silicate solution was prepared from 12.5g of a commercially available sodium
silicate,
containing 29.3% as silicon dioxide and 9.0% as sodium oxide, and 87.5g of
water.
Following the instructions of the subject patent, 60g of the 5% borax solution
was
mixed with 40g of the dilute sodium silicate solution. The mixture was allowed
to
stand for 8 minutes after which time it was further diluted to 0.125 weight %
as silicon
dioxide. It was confirmed repeatedly in our laboratory, that the 1.5% silicon
dioxide
solution of polysilicic acid microgel gelled upon standing at 23 minutes. The
boron to
silicon molar ratio was 1.24. Similarly, the sodium to silicon molar ratio was
1.2. The
final product solids were 0.125% by weight actives.
Example 26 (Borax Solution)
A blank devoid of silica ~vas prepared for study using I OOmL of 0.1M Borax
solution,
48.6 mL of 1 M NaOH solution and 300 mL of water. The solution pH was 13.
The following test protocols were used in conducting the experiments
presented below.
Preparation of Synthetic Standard Furnishes
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WO 99/16708 PCT/US981" ~139
26
= Alkaline Furnish - The alkaline fumish has a pH of 8.1 and is composed of 70
weight percent cellulosic fiber and 30% weight percent filler diluted to an
overall
consistency of 0.5% by weight using synthetic formulation water. The
cellulosic fiber
consists of 60% by weight bleached hardwood kraft and 40% by weight bleached
softwood kraft. These are prepared from dry lap beaten separately to a
Canadian
Standard Freeness (CSF) value ranging from 340 to 380 CSF. The filler was a
commercial ground calcium carbonate provided in dry form. The formulation
water
contained 200 ppm calcium hardness (added as CaC12), 152 ppm magnesium
hardness
(added as MgSO4), and 110 ppm bicarbonate alkalinity (added as NaHCO3).
= Acid Furnish - The acid furnish consisted of the same bleached kraft
hardwood/sofhvood weight ratio, i.e., 60/40. The total solids of the fumish
comprised
92_5% by weight cellulosic fiber and 7.5% by weight filler. The filler was a
coinbination of 2_5% by weight titanium dioxide and 5_0 percent by weight
kaolin
clay. Other additives included alum dosed at 201bs active per ton dry solids.
The pH
of the fumish was adjusted with 50 % sulfuric acid such that the furnish pH
was 4.8
after alum addition.
Britt Jar Test
The Britt Jar Test used a Britt CF Dynamic Drainage Jar developed by K. W.
Britt of
New York University, which generally consists of an upper chamber of about I
liter
capacity and a bottom drainage chamber, the chambers being separated by a
support
screen and a drainage screen. Below the drainage chamber is a flexible tube
extending
downward equipped with a clanip for closure. The upper chamber is provided
with a
2-inch, 3-blade propeller to create controlled shear conditions in the upper
chamber.
The test was done following the sequence below:
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NO 99/16768 PCT/US98/19339
27
Table IV
Alkaline Furnish
Test Protocol
Time Agitator Speed
(seconds) (rpm) Action
0 750 Commence shear via mixing-Add cationic starch.
1500 Add Flocculant.
40 750 Reduce the shear via mixing speed.
50 750 Add the microparticle.
60 750 Open the tube clamp to commence drainage.
90 750 Stop draining.
Table V
Acid Furnish
Test Protocol
Time Agitator Speed
(seconds) (rpm) Action
0 750 Commence shear via mixing.
Add cationic starch and aluni.
10 1500 Add Flocculant.
40 750 Reduce the shear via mixing speed.
50 750 Add the microparticle.
60 750 Open the tube clamp to co"mmence drainage.
90 750 Stop draining.
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In all cases above, the starch used was Solvitose N, a cationic potato starch,
commercially available from Nalco. In the case of the alkaline furnish, the
cationic
starch was introduced at 101bs/ton dry weight of furnish solids or 0.50 parts
by weight
per hundred parts of dry stock solids, while the flocculant was added at
61bs/ton dry
weight of fumish solids or 0.30 parts by weight per hundred parts of dry stock
solids_
In the case of the acid fumish, the additive dosages were: 20lbs/ton dry
weight of
furnish solids of active alum (i.e., 1.00 parts by weight per hundred parts of
dry stock
solids), l Olbs/ton dry weight of furnish solids or 0.50 parts by weight per
hundred
parts of dry stock solids of cationic starch, and the flocculant was added at
6lbs/ton
dry weight of furnish solids or 0.30 parts by weight per hundred parts of dry
stock
solids.
The material so drained from the Britt Jar (the "filtrate") is collected and
diluted with
water to provide a turbidity which can be measured conveniently. The turbidity
of
such diluted filtrate, measured in Nephelometric Turbidity Units or NTUs, 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 arld/or fines. The turbidity values were determined using
a Hach
Turbidimeter. In some cases, instead of ineasuring turbidity, the %
Transmittance
(%T) of the sample was determined using a DigiDisc Photometer. The
transmittance
is directly proportional to papermaking retention performance; the higher the
transmittance value, the higher is the retention value.
SLM (Scanning Laser IVEicroscony)
The Scanning Laser Microscopy employed in the following examples is outlined
in
U.S. Patent No. 4,871,251, issued to Preikschat, F.K. and E. (1989) and
generally
consists of a laser source, optics to deliver the incident light to and
retrieve the
scattered light from the furnish, a photodiode, and signal analysis hardware.
Commercial instruments are available from LasentecTM, Redmond. Washington.
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NO 99/16708 PCT/US98/19339
29
The experiment consists of taking 300 mL of cellulose fiber containing slurry
and placing this in the appropriate mixing beaker. Shear is provided to the
fumish via
a variable speed motor and propeller. The propeller is set at a fixed distance
froni the
probe window to ensure slurry movement across the window. A typical dosing
sequence is shown below.
Table VI
Scanning Laser Microscopy
Test Protocol
Time
(minutes) Action
0 Commence mixing. Record baseline floc size.
1 Add cationic starch. Record floc size change.
2 Add flocculant. Record floc size change.
4 Add the microparticle. Record floc size change.
7 Terminate experiment.
The change in mean chord length of the flocs present in the furnish relates to
papermaking retention performance; the greater the change induced by the
treatment,
the higher the retention value.
Surface Area Measurement
Surface area reported herein is obtained by measuring the adsorption of base
on the surface of sol particles. The method is described by Sears in
Analvtical
Chemistry, 28(12). 1981-1983(1956). As indicated by Iler ("The Chemistry of
Silica",
John Wiley & Sons, 1979, 353), it is the "value for comparing relative surface
areas of
partiele sizes in a given system which can be staildardized." Simply put, the
niethod
CA 02509271 1998-09-17
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involves the titration of surface silanol groups with a standard solution of
sodium
hydroxide, of a know amount of silica(i.c., grams), in a saturated sodium
chloride
solution. The resulting volume of titrant is converted to surface area.
S-value Determination
Another characteristic of colloids in generai, is the amount of space occupied
bv the dispersed phase. One method for determining this was first developed by
R.
Iler and R. Dalton and reported in J. Phys. Chem., 60(1956), 955-957. In
colloidal
silica systems, they showed that the S-value relates to the degree of
aggregation
formed within the product. A lower S-value indicates a greater volume is
occupied by
the same weight of colloidal silica.
DLS Particle Size I1leasurement
Dynanic Light Scattering (DLS) or Photon Correlation Spectroscopy (PCS)
has been used to measure particle size in the submicron range since as early
as 1984.
An early treatment of the subject is found in "Modern Methods of Particle Size
Analysis", H.Barth, editor, Wiley, New York, 1984. The method consists of
filtering
a small volume of the sample through a 0.45 micron membrane filter to remove
stray
contamination such as dust or dirt. The sample is then placed in a cuvette
which in
tum is placed in the path of a focused laser beam. The scattered light is
collected at
90 to the incident beam and analyzed to yield the average particle size. The
present
work used a Coulter N4 unit, commercially available from Coulter Corporation,
Scientific Instruments.
The following examples show the results of a comparison between the
colloidal borosilicate compositions of the invention and the prior art in
several
papermaking furnishes.
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Britt Jar Results
Alkaline Furnish
lOlbs/t Solvitose N followed by 6lbs/t Polymer "A"
'llzrbiditv/3 (NTU) 'I~u'bidity Improvement (%)
Compound O.Olb/t 0.51b/t 1.Olb/t 1.51b/t 2.Olb/t 0.51b/t 1.Olb/t 1.51b/t
2.01b/t
Blank 380
8671 355 310 210 205 6.6 18.4 44.7 46.1
Example 3-.-._ 225 137 160 110 40.8 63.9 57.9 71.1
--- ---- -- --
-
Example 6 180 150 125 170 52.6 60.5-- 67.1 _ 00.3
Example 7 170 145 180 180 55_3 61.8 52.6 52.6
Britt Jar Results
Alkaline Furnish
10lbs/t Solvitose N followed by 61bs/t Polymer "A"
Turbidity/3 (NTU) Turbiditv Improvement (%)
Compound O.Olb/t 0_51b/t 1.01b/t 1.51b/t 2.01b/t 0.51b/t 1.Olb/t 1.51b/t
2.01b/t
Blank 350
8671 316 340 210 180 9.7 2.9 40.0 48.6
Example 8 205 170 140 130 41.4 51.4 60.0 62.9
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Britt Jar Results
Acid Furnish
20lbs/t Alum, I Olbs/t Solvitose N followed by 6lbs/t Polymer "A"
Turbidity/3 (N'I'U) Tlirbidity Improvement (%)
Compound 0.01b/t 0.51b/t 1.01b/t 2_Olb/t 3.01b/t 4.01b/t 0.51b/t 1.Olb/t
2.Olb/t 3.01b/t 4.Olb/t
Blank- 390
8671 330 355 290 270 230 15.4 9.0 25.6 30.8 41.0
Example 6 260 180 155 130 33.3 53.8 60.3 66.7
Britt Jar Results
Acid Furnish
201bs/t Alum, l Olbs/t Solvitose N folioNved by 6lbs/t Polymer "A"
Turbidity/3 (NTU) Turbidity Improvement (%)
Compound 0.OIb/t 0.51b/t 1.01b/t 1.51b/t 2.Olb/t 0_51b/t 1.01b/t 1.51b/t
2.OIb/t
Blank 318
8671 270 288 255 250 15.1 9.4 19.8 21.4
Example 25 - Ex.3 298 255 235 220 6.3 19.8 26.1 30.8
of U.S. Patent No_
4,954,220
Example 13 250 225 180 160 21.4 29.2 43.4 49.7
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Britt Jar Results
Acid Furnish
201bs/t Alum, l0lbs/t Solvitose N followed by 6lbs/t Polymer "A"
- -- -- - --- -- --- -
- Turbidity/3 (NTtJ) Turbidity Improvement (%)
Compound 0.Olb/t 0.51b/t 1.01b/t 1.51b/t 2.Olb/t 0.51b/t 1.01b/t 1.51b/t
2.Olb/t
Blank 360
8671 300 313 275 295 16.7 13.1 23.6 18.1
Example 6 270. 225_.. 180_ 150 25.0 37.5 50.0 58.3
Example 7 260 210 180 195 27.8 41.7 50.0 45.8
Example 8 310 280 210 155 13.9 22_2 41.7 56.9
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Britt Jar Results
Acid Furnish
20Ibs/t Alum, lOlbs/t Solvitose N followed by 6lbs/t Polymer "A"
Turbidity/3 (NTU) Turbidity Improvement (%)
Compound O.Olb/t 0.51b/t 1.01b/t 1.51b/t 2.Olb/t 0_51b/t 1.01b/t 1.51b/t ?
01b/t
Blank 345
8671 245 235 220 230 29.0 31.9 36.2 33.3
Example 13 220 213 195 155 36.2 38.3 43.5 55.1
Example 6 250 200 195 130 27.5 42.0 43.5 62.3
Example 14 . ..250. .228. _ 205 .170..___.. 27.5_-__33.9 _-_ 40.6 _.. 50.7-
__..
Etample 8 270 250 210 200 21.7 27.5 39.1 42.0
Bentonite 290 250 210 205 15.9 27.5 39.1 40.6
Britt Jar Results
Acid Furnish
20lbs/t Alum, l0lbs/t Solvitose N followed by 6lbs/t Polymer "A"
Turbiditv
Turbidity/3 Improvement
(NTU) (%)
Compound O.Olb/t 2.Oib/t 2.Olb/t
Blank 345
Example 26[Borax(only)j 345 0.0
Example 26 [Borax@180X(only)] 280 18.8
8671 275 20.3
Example 24[ 8671 with Borax] 280 18.8
Example 6 115 66.7
Example 14 170 50.7
Example 13 155 55.1
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SLM Data
Acid Furnish
l Olbs/t Alum, 101bs/t Solvitose N followed by 4lbs/t Polymer "A"
Delta @ Maximum Improvement
(microns) (%)
Compound Description @2.Olb/t @2.Olb/t
8671 colloidal silica 3.65
Eiample 13 35.3 867
Example 24 8671+borax(aged 2hrs) 2.4 -34
SLM Data
Alkaline Furnish
101bs/t Solvitose N followed by 61bs/t Polymer "A"
Delta @ Maximum Improvement
(microns) (%)
Compound Description @2.01b/t @2.Olb/t
8671 colloidal silica 23.4
8671 colloidal silica 18.7
8671 colloidal silica 19.8
mean 20.6
standard deviation 2.5
Example 24 8671+borax 23.1 12
Example 13 57.9 181
Note: Example 24 is statisticaliv eot~ivalent to Nalco 8671.
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Example 27
The following work was done on a commercial alkaline fine paper composed of
100%
bleached hardwood virgin fibers. Ash content was 8% via precipitated calcium
carbonate. Consistency was targeted at 1%_ The furnish also contained recycled
coated broke.
SLM Data
Commercial Alkaline Fine Paper,
201bs/t Cationic Starch followed by 2lbs/t Polymer "B"
Delta @ Maximum Improvement
(microns) (%)
Compound Description @2.Olb/t @2.Olb/t
8671 colloidal silica 5.17
Example 6 13.5 161
SLM Data
Alkaline Furnish
101bs/t Solvitose N followed by 6lbs/t Polymer "A"
Delta @ maximum
(microns) Improvement (%)
Compound 0.5lb/t 1_Olb/t 2.01b/t 0.5lb/t 1.01b/t 2_Olb/t
8671 9.5 18.8 27.0
Example 7 35.9 50.3 74.4 277_9 167.6 175.6
Example 6 28.4 57.7 74.1 198.9 206.9 174.4
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SLM Data
Alkaline Furnish
10lbs/t Solvitose N followed by 6lbs/t Polymer "A"
Delta @ maximum
(microns) Improvement (%)
Compound 0.51b/t 1.Olb/t 1.51b/t 2.01b/t 0.51b/t 1.Olb/t 1.51b/t 2.01b/t
8671 7.0 13.1 24.6
Example 3 29.2 42.6 66.9 317.1 225.2 172.0
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Example 28
The following data were collected using an alkaline furnish prepared using
European
hardwood and softwood drylap. The preparation follows that outlined above for
"standard" alkaline fumish. Tiie alkaline fumish lias a pH of 8.1 and is
composed of
70 weight percent cellulosic fiber and 30% weight percent filler diluted to an
overall
consistency of 0.5% by weight using synthetic formulation water. The
cellulosic fiber
consists of 60% by weight European bleached hardwood kraft and 40% by weight
European bleached softwood kraft. These are prepared from dry lap beaten
separately
to a Canadian Standard Freeness value ranging from 340 to 380 CSF. The filler
was a
commercial ground calcium carbonate provided in dry form_ The formulation
water
contained 200 ppm calcium hardness (added as CaClz), 152 ppm magnesium
hardness
(added as MgSO4), and 1 10 ppm bicarbonate alkalinity (added as NaHCO3).
Britt Jar Results
European Alkaline Furnish
lOlbs/t Solvitose N followed by 6lbs/t Polymer `A"
Turbiditv/3 (NTU) Improvement (%)
Compound 0.01b/t 0.51b/t 1.Olb/t 2.Olb/t 0.51b/t 1.Olb/t 2.Olb/t
Blank 465.
8671 404 255 104 13.1 45.2 77.6
N-74907 434 360 263 6.7 22.6 43.4
Example 13 236 80 60 49.2 82.8 87.1
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Britt Jar Results
European Alkaline Furnish
10lbs/t Solvitose N followed by 6lbs/t Polymer "A"
Turbidity
Turbidity/3 Improvement
(NTU) (%)
Compound O.Olb/t 1.Olb/t 1.01b/t
Blank 465
8671 255 45.2
N-74907 360 22.6
Example 13 84.0 81.9
Example 15 33.0 92_9
SLM Data
European Alkaline Furnish
I Olbs/t Solvitose N followed by 6lbs/t Polymer "A"
Delta Improvement
@ Maximum (%)
Compound Description C??2.0Ib/t @2.Olb/t
8671 colloidal silica 16.6
N-74907 colloidal siiica 5.3 -68
Bentonite Natural Mineral 54.4 228
Example 13 Subject of patent 45.5 174
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Example 29
The next fuinish, a commercial European furnish, is used to prepare coated
alkaline
fine paper. The furnish consists of 50% cellulosic fiber, i.e. 100% bleached
kraft fiber,
and 50% filler. The filler is ground calcium carbonate. The furnish has a pH
of 7.4
and an overall consistency of 1.5%. The Britt Jar and SLM testing protocol
consisted
of the following sequence:
Commercial European Alkaline Furnish
Test Protocol
Time Agitator Speed
(seconds) (rpm) Action
0 800 Commence shear via mixing.
5 800 Add Coagulant (Polymer "C"@0.5kg/t).
15 800 Add Alkyl Ketene Dimer Size @ 3kg/t.
20 800 Add Flocculant A(Polymer "G" @ 0.35kg/t).
30 800 Add Flocculant B(Polymer "D"@ 0.35kg/t).
35 800 Add Microparticle @ 0.5kg/t.
40 800 Open the tube clamp to comnience drainage.
800 Begin collecting sample for Turbidity.
75 800 Stop draining.
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Britt Jar Results
Commercial European Alkaline Furnish
See Sequence Above.
Turbidity
Turbidity/3 Improvement
(NTU) (%)
Compound O.Olb/t 0.5kg/t 0.5kg/t
Blank 753
8671 533 29.2
Bentonite 363 51.8
Example 13 393 47.8
Example 15 362 51.9
SLM Data
Commercial European Alkaline Furnish
See Sequence Above.
Delta @ Maximum Improvement
(microns) (%)
Compound Description @2.Okg/t @2.Okg/t
8671 colloidal silica 6.6
N-74907 colloidal silica 4.4 -33
Bentonite Natural Mineral 26.0 294
Example 13 Subject of patent 25.1 280
Example 15 Subject of patent 29.8 352
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42
Example 30
The next furnish, a commercial European furnish, is an acid furnish composed
of 40%
TMP fiber consisting of sulfite bleached and unbleached, 40% is kraft fiber
and the
remaining is coated broke. The filler is kaolin clay. The final product is a
LWC(i.e.,
Light Weight Coated) grade. In particular, the furnish pH was 4.8, with a
consistency
of 0.71 %. The Britt Jar and SLM testing protocol consisted of the following
sequence:
Commercial European Acid TMP Furnish
Test Protocol
Time Agitator Speed
(seconds) (rpm) Action
0 800 Commence shear via mixing.
800 Add 8kg/t of alum and
Skg/Cationic Starch.
800 Add Coagulant Polymer "C"@5kg/t).
30 800 Add Flocculant (Polymer "E"@ 0.66kg/t).
35 800 Add Microparticle @ 2.Okg/t.
40 800 Open the tube clamp to commence drainage_
45 800 Begin collecting sample for Turbidity.
75 800 Stop draining.
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Britt Jar Results
Commercial European Acid TMP Furnish
See Sequence Above.
Turbidity
Turbidity/3 Improvement
(NTLn (%)
Compound O.Olb/t 2.Okg/t 2.Okg/t
Blank 348
8671 335 3.7
N-74907 -- 360= -3.4
- -- - - Bent.onite _ 227 34.8
Example 13 233 33.0
Example 15 247 29.0
SLM Data
Commercial European Acid TM.P Furnish
See Sequence Above.
Delta @ Maximum Improvement
(microns) (%)
Compound Description @2.Okg/t @2.Okg/t
8671 colloidal silica -0.3
N-74907 colloidal silica 3.4 1233
Bentonite Natural Mineral 21.1 7133
Example 13 Subject of patent 10.7 3667
Example 15 Subject of patent 10.0 3433
Sequence the same, liowever the dosages of polymers changed. Alum was
added at 6.7kg/t, cationic starch added at 5_0kg/t, the coagulant was added at
5.Okg/t,
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the flocculant was added at 0.66kg/t just prior to the microparticle being
added at
2.Okg/t.
Example 31
The next furnish, a commercial European furnish, is an alkaline furnish. The
alkaline
furnish consists of 32% Kraft fiber, 48% broke, and 20% ash. The Kraft fiber
consists
of 63% hardwood and 37% softwood kraft pulp. The 20% ash is composed of equal
components of precipitated and ground calcium carbonate. The furnish pH was
8.25,
with a consistency of 1.2%. The SLM testinc, protocol consisted of the
following
sequence: at 30 seconds the coagulant, Polymer "C", was added at 1.0kg/t; this
was
foll'owed 30 seconds later with the flocculant, Polymer "F" at 0.5kg/t; and
the last
additive was the microparticle at 90 seconds and at 1.Okg/t.
SLM Data
Commercial European Alkaline Furnish
See Sequence Above.
Compound Description @1.Okg/t @1.Okg/t
8671 colloidal silica 19.8
N-74907 colloidal silica 31.3 58
Bentonite Natural Mineral 26.0 31
Example 13 Subject of patent 36.1 82
Example 15 Subject of patent 42.1 113
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Example 32
The next furnish, a commercial European fumish, is used to make a neutral
coated
wood-containing sheet . The fumish consisted of CTMP, coated broke and some
Kraft pulp. The fumish pH was 7.5, with a consistency of 0.7%. Of this some
20%
was ash. The SLM testing protocol consisted of the following sequence:
beginning
with cationic starch at 8kg/t; at 60 seconds the coagulant, Polymer "C", was
added at
4.8kg/t; this was followed 30 seconds later with the flocculant, Polymer "E"
at
0.9kg/t; and the last additive was the microparticle at 120 seconds and at
2.Okg/t.
SLM Data
Commercial European CTMP Furnish
See Sequence Above.
Delta @ Maximum Improvement
(microns) (%)
Compound Description @1.Okg/t @1.Okg/t
8671 colloidal silica 8_98
N-74907 colloidal silica 3.37 -62
Example 13 Subject of patent 18.9 110
Example 15 Subject of patent 27.3 204
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:
