Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02509471 1998-09-17
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.
Backeround 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. Background 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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2
Another aspect of papermaking 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 ranginj in size from about S to about
1000 nm
consisting of for example cellulosie fines, mineral fillers (employed to
increase
opacity, brightness and other paper characteristics) and other small particles
that
- jenerally, without the inclusion of one or more retention aids; would in
significant
portion pass through the spaces (pores) beriveen 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 papermaking 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
ofpoor
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.
CA 02509471 1998-09-17
3
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 pan 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 irreversible 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
requiremerits 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 floceulant 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 vay (after shear), with no deleterious
impact on
formatiori.
One such program employed to provide an improved combination of retention
and dewatering is described in United Stated Pat. Nos. 4,753,710 and
4,913,775, to
Langley et al.
CA 02509471 1998-09-17
4
In the method disclosed in Langley et al., a high molecular weight
linear cationic polymer is added to the aqueous cellulosic papem~aking
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. 4,388,1 SO 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.j., wherein the microparticle is added before the screen and the
flocculant after
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
rnicroparticle, a coagulant and flocculant system_ In such a system a
coagulant is first
added, for instance a low molecular weight synthetic 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 system, 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 floccuIant. Such a
flocculant
generally is a high molecular weight synthetic polymer which bridges the
particles
andlor agglomerates, from one surface to another, binding the particles into
larger
agglomerates. The presence of such large agglorrierates in the furnish, 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, preferably a colloidal borosilicate is utilized as the
mieroparticle.
Surprisingly we have found that borosilicates provide improved performance
over
other microparticle programs, and especially those using colloidal silica sots
as the
microparticIe. The borosilicate microparticles of the invention allow the
production of
paper and board having improved levels of retention, formation, uniform
porosity, and
overall dewatering.
~ummarv of the lnvention
One aspect of the invention comprises a borosilicate retention aid
composition.
The borosiIicates, 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
furnish
from about 0.00005 to about 1.25% by weight, based on the weight of the dry
fiber in
the furnish, 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
CA 02509471 1998-09-17
6
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
I .25%
by weight of the dry weight of the fiber in the furnish. The flocculation of
components
of the papenmaking 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 O.OI 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 l :l 000
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, 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
borosi licate.
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
CA 02509471 1998-09-17
6/1
having a mole ratio of boron io 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
panicle size of
from about I to 2000 rim; and a surface area of from about I S 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 flocculent having a molecular
weight
greater than 500,000 Daltons; subjecting the furnish to papermaking
conditions; and
recovering a ceilulosic 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 1
to 2000 nm; and a surface area of from about 15 to 3000 m2 /g, and from about
0.005
to 5.0% by weight, based on fiber in the funnish, of a cationic starch; and
then
flocculating the furnish; whereby the drainage rate of water from the paper
mill
furnish 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 I :1000 to about 100:1, a mole ratio of alkali
metal to
silicon of from about 6:1000 to about I .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 furnish 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
CA 02509471 1998-09-17
6/2
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: I .
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 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. 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.
Detailed Descriution of the Inyention
'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 I : 1 00 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: 1 000 to 1.04: I . The microparticle retention aid is
preferably a
colloid of borosilicate having a chemistry similar to that 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
CA 02509471 1998-09-17
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PCT/US98119339
7
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 I nm to I micron. When a colloidal borosilicate is utilized the panicle
size will
generally be in the range of from I nm to 200nm and preferably from I to 80nm,
and
most preferably 20-80nm. 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 I S to
3000m2/g
and-preferably 50 to 3000mz/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 300Um2/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. Alternatively, 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 S 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 B,O3. 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
CA 02509471 1998-09-17
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8
without pH adjustment. It is sometimes advisable to conduct the reaction at a
pH of
'1.5 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 furnish 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 boiosilicate in an amount of from about
0.001 to
about 0.5% by weight based on dry weight of fiber in the furnish. 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 0.0~ 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 weight of fiber in the
papenmaking
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.
This invention is also directed to a.method for increasing retention and
drainage of a papermaking furnish on a papermaking machine which comprises the
k , .,
CA 02509471 1998-09-17
W O 99/a 6708 PCT/US98119339
9
steps of 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
panicle,
preferably a colloidal borosiIicate. The borosilicate may be added to the
papermaking
furnish 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
O.OS to about . - - .
1.5% by weight based on the dry weight of fiber in the furnish. In yet another
alternative, 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 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
system
prior to sheet formation. The preferred addition point is the thick stock pulp
before
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WO 99/167Q8 PCT/t)S981'~?.39
dilution with whitewater. This application results in increased cleanliness of
the
papermaking operation which otherwise experiencea~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
v 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-containing, 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
furnish,
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
papermaking 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
dew~atering in the
f r
CA 02509471 1998-09-17
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PCTlUS98119339
11 -
production of dry-lap gulp, 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
micraflocs
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 sta~~e, 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 dr centriscreen, or one may insert into the
apparatus
a shear mixer or other shear stake for the purpose of providing shear, and
preferably a
high degree of shear, subsequent to the addition of the polymer.
.
CA 02509471 1998-09-17
WO 99/16708
PCT/US98/t x339
' 12
The floccuIants 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
variety 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
w 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 floccuiants 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 have been prepared from as little as 1 mole percent cationic
monomer
to 100 mole percent cafionic 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. . _ . .
CA 02509471 1998-09-17
\ WO 99116708
PCT/US98/t 9339
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, diallylcyclohexyiamine hydrochloride (DACHA HCl),
diallyldimethylammonium chloride (DADMAC),
methacrylamidopropyltrimethylammonium chloride (MAPTAC) and allyl amine
(ALA). Cationized starch may also be used as a llocculant 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 preferabiy water-soIubie or dispersible vinyl polymers
containing 1 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 acryiamide 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 aikali metal and ammonium salts. The anionic high molecular weight
polymers useful in this invention may also be either hydrolyzed acrylamide
polymers
or copolymers of acrylamide or its homologues, such as methacrylamide, with
acrylic
acid or its homologues, such as methacrylic acid, or with polymers of such
vinyl
monomers as malefic acid, itaconic acid, vinyl sulfonie acid, or other
sulfonate
containing monomers. Anionic poiymers may contain sulfonate or phosphonate
functional groups or mixtures thereof, and may be prepared by derivatizing
polyacrylamide or polymethacrylamide polymers or copolymers. The most
preferred
f ,
CA 02509471 1998-09-17
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PCT/US98/19339
_.
14
high molecular weight anionic tlocculants are acrylic acid/aerylamide
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 other non-ionic vinyl monomer. When used herein the polymers and
copolymers of the anionic vinyl monomer may contain as little as 1 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 surprising effects using the
borosilicate
particles of the invention with high molecular weight anionic water soluble
flocculants
with the addition of a cationic coagulant.
Nonionic floccuiants 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 vinyi 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 andlor
dispersible
flocculants useful herei7 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/I6598,
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 02509471 1998-09-17
I$
governed by the solubility or dispersiblity of the resuhing product in the
papermaking
furnish.
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 from
wheat, potato and rice. These materials may in turn be reacted to substitute
ammonium groups onto the starch backbone, or canonize 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-chloro-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 ofthis invention to describe
means for
the canonizing 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 celluIosic 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, molecular 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 without 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, biocides 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 02509471 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 micropariicles 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 commercially available low-to mid molecular
weight
water soluble polyalkylenepolyamines including those prepared by the reaction
of an
alkylene polyamine with a difunctional alkyl halide. Materials of this type
include
condensation polymers prepared from the reaction of ethylenedichioride 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 dia11y1dimethylammonium
halides, especially diallyldimethyIammonium chloride,
dialkylaminoalkylacrylates,
dialky-laminoalkylacrylaie quaternaries, and the like where 'alkyl' is meant
to
designate agroup having 1-4, and preferably 1-? carbon atoms. Preferably
'alkyl' is
methyl. These monomers are exemplified by such materials as
dimethylami:=oethyl
acrylate, dimethyl-aminoethyl methacrylate and their water-soluble quaternary
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
weight
.... ..a. .. ,. . ,
CA 02509471 1998-09-17
'WO 99!16?08
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 papetlnaking 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 may 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 arid
utilities of the invention and are not meant to limit the invention unless
otherwise
stated in the claims appended hereto.
Example I-2~
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 commercialiy 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 Company,
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 through a column of the regenerated washed
resin.
The resultant silicic acid was collected.
,. ..,.
CA 02509471 1998-09-17
V110 99116708 PCT/US98i' ~-'i39
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 siIicic 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.
CA 02509471 1998-09-17
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19
Table I
Colloidal Borosilicates
Amts Used Molar Ratio Final
Example Borax NaOH Acid Sol B/Si Na/Si pH
1 0.02SM(SOmL)O.1M(18.3mL) 130mL of 0.042 0.037 8.5
I.032g/mL
2 0.025M(SOmL)O.1M(l8.SmL) 140mL of 0.028 0.025 8.0
1.046g/mL
-. - _ 3 _ 0.025M(SOmL).O.1M(l8.SmL).140mL of,_0.039__0.034 8.0
_
1.032g/mL
4 _ 0.025M(SOmL)O.1M(22.7g) 140mL of 0_028 0.027 8.S
I .045g/mL
0.02SM(SOmL)O.1M(24.3g) 140mL of 0.029 0.029 9.4
1.043 g/mL
6 0.1M(SOmL) 1.OM(9.7mL) 140mL of 0.117 0.116 9.4
1.043g/mL
7 0.1 M(50mL) 1.OM(9.7mL) 140mL of 0.109 0.107 9.2
1.046gJmL
8 O.1M(27.6mL)1.OM(10.9mL} 140mL of 0.063 0.062 8.7
1.046g/mL
9 --- -~ 249g of 0 0.208
I .047g/mL
O.1M(SOmL) 1.OM(9.7g) 70mL of 0.223 0.220 9.5
1.045g/mL
11 O.1M(SOmL) 1.OM(9.7g) 70mL of 0.2?3 0.220 9.S
1.045g/mL
12 O.1M(SOmL) l.OM(9.7g) lOSmL of 0:149 0.146 9.2
~
1.045e/mL
.~_ ... . ....
CA 02509471 1998-09-17
WO 99/I6708 PCT'/US98/19339
TABLE 1 (Continued)
13 O.1M(446mL) 4.57mL of 1343mL 0:117 O.I15 9.1
of
. . SOwt% NaOH 1.040g/mL
14 0.1 M(223mL)2.39mL of 1307mL 0.063 0.062 8.5
of
SOwt% NaOH I .040g/mL. -
- ~
15 0.1 M(SOmL) I .OM(24.3mL)1 SOmL 0.117 0.201 9.9
of
I .040d/mL
16 0.1 M( 100mL)2.0mL of 100mL of 0.352 0.510 i 0.6
SOwt% NaOH 1.040g/mL
17 0.1 M( 100mL)2.OmL of SOmL of 0.704 1.02 I I.I
SOwt% NaOH 1.040g/mL
~
18 O.IM(l7mL) . 2.OmL of 150mL of 0.039 0.242 11.0
SOwt% NaOH 1.040g/mL
19 O.1M(SOmL) 2.OmL of 150mL of 0.117 0.281 10.7
SOwt% NaOH 1.040g/mL
20 0.1 M(SOOmL)12.81 mL of I SOOmL 0.1 0.202 10.1
of I 7
SOwt% NaOH 1.040g/mL
21 O.1M(SOOmL) 12.81mL of 1500mL 0.117 0.202 10.1
of
SOwt.' NaOH 1.040g/mL
22 0_1M(SOmL) 1.OM(24.3mL) 150mL of 0.117 0.201 10.I
1.040,g/mL
23 0.1 M(SOmL) 1.0M(9.7g) 1 SOmL 0. I 0. 8.9
of 17 I
16
1.040g/mL
.,
y... . ~ v
CA 02509471 1998-09-17
JVO 99/16708 PCTlUS98J19339
21
The commercially available compounds defined in Table II below are used
throughout the following Examples. Unless otherwise indicated, all are
available from
Nalco Chemical Company, One Nalco Center, Naperville, Illinois 60563-1 i 98..
~ _, , .a.
,.. ,
CA 02509471 1998-09-17
W 0 99/16708 PCTIU S 98/' ~'i39
22
Table II ..
Product Description
Nalco~ 8671 A commercially available colloidal silica.
This material has an
average particle size of 4nm, a surface area
of 750 m2/g, and about
I 5% by weight Si02
Nalco ~U 74907A commercially available colloidal Silica having
an average
- particle size of 7nm, a surface area of 372m21g,
and containing
about 15% by weight as Si02
- Polymer "A" A commercially available copolymer having a
molecular weight
greater than I million daltons containing approximately
10 mole
percent of dimethylaminoethylacrylate, methyl
chloride quaternary
and 90 mole percent acrylamide copolymer containing
approximately 26 percent by weight solids.
Solvitose A cationized potato starch which is cold water
N 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 benzyl chloride
quaternary and 90
mole percent acrylamide copolymer.
Polymer "C" A conunercially 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 1 million daltons containing
approximately 30 mole
percent sodium acrylate-and 70 mole percent-aerylamide.
Polymer "E" A commercially available copolymer flocculant
having a
" . ., . ~,." _ . . . .
CA 02509471 1998-09-17
- V1~0 99/16708
PCT/U598119339
23
molecular weight greater than 1 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 dimethylaminoethyiacylate-
methylchloride quaternary and 90 mole percent
acrylamide.
BMA 0 a colloidal silica sot 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 commercially 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, 2498 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 Si02.
:.... . fi . ...~._ ....... ...,._.~__.._
~ .,.
CA 02509471 1998-09-17
WO 99/1608 PCT/US98/~ 2339
24
Table III
ProperfX, omp~risons
Sample Id. S.A. (m-/g) S-Value DLS Dia. (nrn)
8671 700 63.5 12.6
BMA 0 65.7
BMA 670 489 32.6 I S.4
BMA 780 435 21.6 145
Example 13 1210 24.2 56.2
Example 8 1052 37.1 61.1
.. . ,a,CS4~ 619 . 9g .. . . _ . _ 4.5
... .
ACSS' 545 47 13
ACS6a S00 3I 17
Sample 1 -. SO 4.6
Sample 2 37 13.3
Sample 3 31 16.5
Example 20 35.6 58.5
"Reference: Nordic Yulp and Yaper, 1 1 ( 1 ). ( 1 yyb), m.
bReference: Colloids and Surfaces A, ~$ (1996), 89.
Definition: S.A. = Surface Area as determined via method described below.
DLS = Dynamic Light Scattering is a method used to determine average
panicle size described below.
.t .. _ , w .,..
.~. __ . .. . , w. _ . ..
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PCf/US98/I 9339
Example 24 (blend of colloidal silica sol and borax)
A "simple blend" control was prepared by mixing a commercially available
colloidal silica and borax. A mixture was prepared at room temperature
consisting of
SOg of 0. I M borax solution, 92.38 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 of U.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
fomnation 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 S% by weight borax solution was
prepared
from Sg of sodium orthoborate~decahydrate and 95g of water. A 3.75% sodium
silicate solution was prepared from I2.Sg of a commercially available sodium
silicate,
containing 29.3% as silicon dioxide and 9.0% as sodium oxide, and 87.~g 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 v~~as confirmed repeatedly in our laboratory, that the 1.5%
silicon dioxide
solution of polysilicic acid microgeI gelled upon standing at 23 minutes. The
boron to
silicon molar ratio was I:?4. Similarly, the sodium to silicon molar ratio was
1.2. The
final product solids were 0.125% by weight actives.
Exnmpje 26 (Borax Solution)
A blank devoid of silica was prepared for study using 100mL of O.IM 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.
Prem3ration of Synthetic Standard Furnishes
~.:. _..~. . _ .__. ._ ... ..,... ...___... _
~,
CA 02509471 1998-09-17
VVO 99/16708 PCT/US98~"'Z39
26
~ Alkaline Furnish - The alkaline furnish 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
cellulosie 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 CaCl2), 152 ppm magnesium
hardness
(added as MgS04), and 110 ppm bicarbonate alkalinity (added as NaHC03).
~ Acid Furnish --The acid furnish consisted of the same bleached kraft
hardwood/sofrivood weight ratio, i.e., 60/40. The total solids of the furnish
comprised
92.5% by weight cellulosic fiber and 7.5% by weight filler. The filler was a
combination 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 furnish 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 1
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 clamp 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:
... . ~ .,. . , .... . .
.. _.F.. .... , .rt._ .._..
CA 02509471 1998-09-17
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PCT/US98/19339
27
Table IV
Alkaline Furnish
Test' Protocol
Time Agitator
(seconds)Speed _ Action
(rpm)
0 750 Commence shear via mixing-Add cationic
starch.
10 1500 Add Flocculant.
40 . ?50 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
(seconds)Speed Action
(rpm)
0 750 Commence shear via mixing.
Add cationic starch and alum.
10. 1500 Add Flocculant.
40 750 Reduce the shear via mixing speed.
50 750 Add the microparticle.
GO 750 Open the tube clamp to commence drainage.
.
90 750 Stop draining.
~.... . . , , , , .,."
CA 02509471 1998-09-17
WO 99/16708 PCT/tJS98/19339
28
In all cases above, the starch used was SoIvitose 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 pans
by weight
per hundred parts of dry stock solids, while 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.
In the case of the acid furnish, the additive dosages were: 201bs/ton dry
weight of
furnish solids of active alum (i.e., 1.00 pans by weight per hundred pans of
dry stock
solids), 1 OIbs/ton dry-weight of furnish solids or 0.50 pans by weight per
hundred
parts of dry stock solids of cationic starch, and the flocculant was added at
6Ibs/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 f ller arid/or fines. The turbidity values were determined using
a Hach
Turbidimeter. In some cases, instead of measuring turbidity, the %
Transmittance
(%T) of the sample was dete~rnined 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 l~Scannin,~Laser lflicrosco~yl
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 LasentecT"", Redmond, Washington.
.. .,~... .. ..
CA 02509471 1998-09-17
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
furnish via
a variable speed motor and propeller. The propeller is set at a fixed distance
from 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 jVleasu,~ement
Surface area reported herein is obtained by measuring the adsorption of base
on the surface of sot particles. The method is described by Sears in a 'cal
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
particle sizes in a given system which can be standardized." Simply put, the
method
..~._..,t __ . .._. . .....~. ...__....
* .. . ..., ... . .,
CA 02509471 1998-09-17
WO 99/16708 PCT/US98J19339
involves the titration of surface silanol groups with a standard solution of
sodium
hydroxide, of a know amount of silica(i.e., grams), in a saturated sodium
chloride
solution. The resulting volume of titrant is convened to surface area.
S-value Determination
Another characteristic of colloids in general, is the amount of space occupied
by t:ne dispersed phase. One method for determining this was first developed
by R.
Iler and R. Dalton and reported in T. Phys. Chem., ,6(1956), 955-957. In
colloi al
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.
pLS Particle Size llZeasurement
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", I3.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 bet'veen the
colloidal borosilicate compositions of the invention and the prior art in
several
papermaking furnishes.
.,u_.. ~.t_.. . . ...... . ..."..._..w. .. ... .... .
. ... . .., . ."...._ ,y... .... . ,.,.......... .,.... , _ . .. ..~,..
....._.. . . .
CA 02509471 1998-09-17
~' WO 99116708 PCT/US98/19339
31
Britt Jar Results
Alkaline Furnish
lOlbs/t Sotvitose N followed by 6lbs/t Polymer "A"
~lwbidity/3 'I~rbidity
(NTLJ) Improvement
(/)
Compound O.OIb/t l.Olb/t1.51b1t2.Olb/t0.51b/ti.Olblt1.51b/t2.01b/t
0.51b1t
Blank 380
8671 ' 355 310 210 305 6.6 18.4 44.7 46.1
.':-__.' _-_._.:.Example3___.-_:..~.._._.5.___.137..-_160_.__11040.8 _ 57.9
7L1
63.9
Example 6 180 150 125 _-_ ___ _ 67.1 ~ 55.3
170 02.6 60.5 "
Example 7 170 195 180 180 55.3 61.8 52.6 52.6
Britt Jar Results
Alkaline Furnish
_ l Olbs/t Solvitose N followed by 6lbs/t Polymer "A"
Wrbidity/3 (NTLJ) 'I~rbidity Improvement
(%)
Compound O.Olblt 0.5Ib/t l.Olb/t 0.51b1t l.Olb/t 1.51b/t
1_51b/t 2.Olb/t 2.OIb/t
Blank 350
8671 316 340 210 180 9.7 2.9 40.0 48.6
Example 205 170 140 130 41_4 51.4 60_0 62.9
8
.. ..r . ....~.w ......,~ .. .. .
,..,..... . . ."...- ...
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PCT/US98~' X339
32
Britt Jar Results
Acid Furnish
201bs/t Alum, l0lbs/t Solvitose N followed by 6lbs/t Polymer "A"
-- - Wlirbidity/3 (1\TTLJ) ~ ~rbiditv Improvement (%)
Compound 0.01b1t 0.51b1t l.OlbJt Z.Olblt 3.OlbJt 4.Olblt 0.51bJt l.OlbJt
2.Olblt 3.Olblt 4.Olblt
Blank 390
8671 330 355 290 2 70 230 15.4 9.0 25.6 30.8 41.0
trample 6- - - 260 180 155 130 33.3 53.8 60.3 66.?
Britt Jar Results
Acid Furnish
201bs/t Alum, 101bs/t Solvitose N followed by 6lbs/t Polymer "A"
~rbidity/3 ~rbidity
(NTU) Improvement
(%)
Compound O.OIbIt0.51b/tl.Olblt1.51bit2.Olblt0.51bitl.Olb/t1.51b1t2.Olblt
Blank 318
8671 270 288 255 250 15.1 9.4 19.821.4
Example 25 - 298 255 ?35 220 6.3 19.8 26.130.8
Ex.3
of U.S_ Patent
No.
4,954,220
Example 13 250 225 180 160 21.4 ?9.2 43.449.7
. ..,..~_.... _ .-.......__-....~._- __... .
.._~ . . _*.Y ..
CA 02509471 1998-09-17
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PCT/US98/19339
33
Britt Jar Results
Acid Farnisb
201bs/t Alum, 101bs/t Solvitose N followed by 6lbs/t Polymer "A"
_ ____.__~ ______.___..____-__. ~rbidity
. . ._..._ Improvement
,I,~,biditv/3 (%)
(NTLJ)
_ Compound O.Olb/t
l.Olblt1.51b/t2.Olb/t0.51b/tl.Olb/t1.51b/t2.Olblt
0.51b/t
Blank 360
8671 .. 300 313 275 295 16.7 13.1 23.6 18.1
_ . ...___ _.. _...._._____-~..:. . . 150 25.0 37.5 50.0 58.3
_ _ . _. Example .... 270_ _ I80_
6. . 225_..
_ __
Example ? _._ 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
_ . .. , ...w ..j,..._.. . __~.._._.~~.___ ._ .
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34
Britt Jar Results
Acid Furnish
201bs/t Alum, l Olbs/t Solvitose. N followed by 6lbs/t Polymer "A"
Turbidity/3 Turbiditv
(NTtT) Improvement
(%)
Compound O.OIb/t
l.Olb/t1.51b/t2.Olblt0.51b/tl.Olb/t1.51b/t2.Olb/t
0.51b/t
Blank 345
8671 24$ 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
. .._ .._._:._.:.._.._._:_._:_.._..__ _... _ _ .._ . __..
_._..33.9.__.40.6__- 50.7_..._._
Example 14- . _. ..._.250_228-. 205. _ 27.5_ __ .__
- 170.._
_.
Example 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
201bs/t Alum, l Olbs/t Solvitose N followed by 6lbs/t Polymer "A"
Turbiditv
Turbidity/3 Improvement
(NTIn (%)
Compound O.OIb/t 2.Olb/t 2_Olb/t
Blank 345
Example 26[Borax(only)) 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
. . ., . . ..........~..~ .._ ... .._.. , w_......~. .....,_ _. . .. ...
.,_. ~.,__.. _ . . _._ _. . . _ ...,~_.. . ..,_. .. .
CA 02509471 1998-09-17
WO 99/16708 PCT/US98/19339
SLM Data
Acid Furnish
l Olbs/t Alum, lOlbs/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
Evample~ 13-. ~ - _ - ____ . - _ .. - 35.3 867
Example 24 8671+borax(aged 2hrs) 2.4 -34
SLM Data
Alkaline ish
Furn
lOlbs/t Solvitose N followed 6lbs/t Polymer"A"
by
Delta Improvement
@ Maximum
(microns) (
Compound Descri ption @2.Olb/t @2.Olblt
8671 colloida l silica 23.4 .
8671 colloidal 18.7
silica
8671 colloidal 19.8
silica
.
mean 20.6
standard 2.5
deviation
Example 24 8671borax 23.1 12
Example 13 57.9 181
Note: ~xamole ~4 is statistical)v eq~jivalent to Nalco 8671.
......._...... _: _.....~_..~..~._..__._w_~~_a~~_~ __.. . -.. _ .
_,~~ ~....... . . ,.. . . ... . ~.,..~ _..... ..
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36
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
SLIfI Data
Alkaline Furnish
101bs/t Solvitose N followed by 6tbs/t Polymer "A"
Delta
@ maximum
(microns) Improvement (~6)
Compound 0.51b/tl.Olblt 0.51b/t 1.01b/t
?.Olb/t 2.Olb/t
8671 9.5 . 18.8 27.0
.
Example 35.9 50.3 74:4 277.9 167.6 175.6
?
Example 28.4 57.7 74.1 198.9 206.9 174.4
6
r...... ..._.__ ~__... ~.__....,.
_. , r._ ..,,. ___.._ . ~.._. ,.. .._..,._.~_... ... .. ..
CA 02509471 1998-09-17
WO 99/,16708 PCT/US98/19339
37
SLM Data
Alkaline Furnish
101bs/t Solvitose N followed by 6lbs/t Polymer "A"
Delta Q maximum
(microns) Improvement (%)
Compound 0.51b/t l.Olb/t 1.51b/t 2.Olblt 0.51b/t l.Olb/t 1.51b/t 2.Olb/t
8671 7.0 13.1 24.6
Example 3 29.2 42.6 66.9 317.1 225.2 172.0
.. ,. ._ _.~...., _....".~ ._ .......w.,.. ,.~ ..... .. ..
~___ .. . ...~ . .. ..~~.. ..f...~.
CA 02509471 1998-09-17
WO 99116708 . PCT/US98~ X39
38
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 furnish. The alkaline furnish 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 European bleached hardwood kraft and
40°f° 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 ?00 ppm calcium hardness (added' as CaClz), 152 ppm magnesium
hardness
(added as MgS04}, and 1 I 0 ppm bicarbonate alkalinity (added as NaHC03)_
Britt Jar Results
European Alkaline Furnish
141bs/t Solvitose 1V followed by 6lbs/t Polymer 'A"
Turbiditv/3 Improvement
(NTT.I) (%)
_ _
~
Compound O.OIb/t 0.51b/tl.Olb/t 0.51b/tl.Uib/t2.OIb/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 I3 236 80 60 49.2 82.8 87.I
~, ., .........., .__...... .~"..."m,.. m__.....
CA 02509471 1998-09-17
WO 99/16708
PCT/US98/19339
39
Britt Jar Results
European Alkaline Furnish
I Olbs/t Solvitose N followed by 6lbs/t Polymer "A"
Turbidity
Turbidity/3 Improvement
(~
Compound O.Olb/t l.Olb/t l.Olb/t
.... _.._ . .. .. _.... . . 465
... Blank
8671 255 45.2
N-~490~ 360 22.6
Example 13 84.0 . 81.9
Example 15 33.0 92.9
SLM Data
European Alkaline Furnish
l Olbs/t Solvitose A"
N followed by 6lbs/t
Polymer "
. Delta Improvement
Q Maximum (%)
Compound Description C2.Olb/t . ~2.Olb/t
86 r 1 colloidal silica 16.6
N-?4907 colloidal silica 5.3 -68
Bentonite Natural Mineral 54.4 228
Example 13 Subject of patent 45.5 174
. _ _... ...... -~__.~_.~.._._..... _.._ . ~_~ .__~..._
,w... ,~_._.... . . . . , ."" ..._ .... ,....
CA 02509471 1998-09-17
WQ 99!16708 - PCTNS98/19339
Example 29
The next furnish, a commercial European furnish, is used to prepare coated
alkaline
fine paper. The furnish consists of SO% ceIlulosic fiber, i.e. 100% bleached
kraft fiber,
and SO% 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
(seconds)Speed Action
(rpm)
0 ( 800 ~ Commence shear via mixing.
5 800 Add Coagulant (Polymer "C"@O.Sk~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 @ O.Skg/t.
40 800 Open the tube clamp to commence drainage.
800 BeDin collecting sample for Turbidity.
75 800 ~ _ . Stop draining.
.~ ..... . .. ..........r~,.~.......~...,~.~.~..~.~ .._...w._
. . , ". . . ~.... ... .... , . ~.,.,. .. _ . . .
CA 02509471 1998-09-17
WO 99/16708 PCT/US98/19339
41
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 ' ~ 4?.8
Example 15 362 51.9
SLM Data .
Commercial European Alkaline Furnish
See Sequence Above.
Delta ~ MaximumImprovement
(microns) (%)
Compound Descri ption C~32.Okg/t t~2.Okg/t
8671 colloidalsilica6.6
N-7490? rnlloidal 4.4 -33
silica
Bentonite l~Tatural 26.0 294
Mineral
Example 13 Subject 25.1 280
of patent
Example 15 Subject 29.8 352
bf patent
,.. , ....._,.~..~.w .._._...,....._~...~~~...._ _._.....,.
. . .~_.~....._~. a.~__~ , . _ .-.__.... .... _ .
CA 02509471 1998-09-17
WO 99!16708 PCT/US98h Q339
Example 30
42
The next furnish, a commercial fiuropean furnish, is an acid furnish composed
of 40%
TMP f ber 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 '
(seconds)Speed Action
(rpm)
0 800 Commence shear via mixing.
I 0 800 Add 8kg/t of alum and
Skg/Cationic Starch.
IS 800 Add Coagulant Polymer "C"@Skg/t).
30 800 Add Flocculant (Polymer "E"@ 0.66kg/t).
35 80U Add Microparticle @ 2.Okg/t.
40 800 Open the tube clamp to commence drainage.
4S 800 Begin collecting sample for Turbidity.
7S 800 ~ Stop draining.
.__ .. . .. _ .. ...,..~.r~~~~.~~~_~_____ . _
.., "m- .a"..... . _ . .~.._.. , ...T"...._,..~.
CA 02509471 1998-09-17
WO 99f16708
PCT/US98/t 9339
43
Britt Jar Results
Commercial European Acid TMP Furnish
See Sequence Above.
- Turbidity
_ _ . _ . . Turbidity/3 Improvement
(NT~. . .... . _ . . (~) . ........_
Compound O.Olb/t 2.Okg/t 2.Okg/t
Blank 348
8671 335 3.7
_.. ..... : . _ . _ :__ . 360 -3.4 ' _ _ . . .
. _= N-74907 -: -
_ : _ ~ _:: _ Bentonite _ . 227 . ... 34.8
. . . . .
Example 13 233 33.0
Example 15 . 247 29.0
SLM Data
Commercial European Acid TMP Furnish
See Sequence Above.
Delta (~ MaximumImprovement
(microns) (%)
Compound Description ~2.Okg/t (32.Okg/t
8671 colloidal silica-0.3
N-74907 colloidal silica3_4 1233
Bentonite Natural Mineral21.1 7133
Example 13 Subject of patent10.7 3667
Example 15 Subject of patent10.0 3433
Sequence the same, however the dosages of polymers changed. Alum was
added at 6_7kg/t, cationic starch added at S.Okg/t, the coagulant was added at
S.Okg/t,
. , . , . . .~ ._., ~..,:_ .._._ _.~,~ _. ~ ._.~~ _.._.__...,. . .
. ._..~~. ~._ ..... . r ~...,.. .~ . m. .
CA 02509471 1998-09-17
WO 99/16708 PCT/US98/19339
44 . -
the flocculant was added at 0.66kg/t just prior to the microparticle being
added at
2.Okg/t.
Example 3l
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 testing protocol consisted of the
following
sequence: at 30 seconds the coagulant, Polymer "C", was added at l .Okg/t;
this was
followed 30 seconds later with the floccuiant, Polymer "F" at O.Skg/t; and the
last
additive was the microparticle at 90 seconds and at l.Okglt.
SLM Data
Commercial European Alkaline Furnish .
See Sequence Above.
Compound Description C~?l.Okg/t (~l.Okg/t
86?1 colloidal silica 19.8
N-?4907 colloidal silica 31.3 58
Bentonite Natural Mineral 26.0 31
Example 13 Subject of patent36.1 82
Example 15 Subject of patent42.I 113
__..,._.,_..._.~_.__._..~.~..._.~~...~...~,~_...-... __
,. ..., _ ....,. ,..... .
CA 02509471 1998-09-17
JVO 99/16708 PCT/US98/19339
Example 32
The next furnish, a commercial European furnish, is used to make a neutral
coated
wood-containing sheet . The furnish consisted of CTMP, coated broke and some
Kraft pulp. The furnish 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 Q Maximum Improvement
(microns) ('/ )
Compound Descri ption C~3l.Okglt (~l.Okg/t
8671 colloidalsilica8.98
N-74907 colloidal 3.37 -62
silica
Example 13 Subject 18.9 110
of patent
Example 15 Subject 27.3 204
of patent
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:
,_.....,. . . .., w.~.._.~...~,-._~,...~...~.-,.~...~.w~. _... .
