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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a composition comprising an aqueous cellulosic
furnish, cationic polymer and a modified lignin and methods using the
composition for making paper or paperboard having improved properties in
the areas of drainage, retention and formation.
2. Brief Description of the Background Art
In the production of paper or paperboard from a dilute aqueous cellulosic
furnish improvements in retention and drainage and in the formation
properties of the final paper or paperboard sheet are particularly
desirable. It is well known by those skilled in the art that these
parameters are frequently in conflict with each other. For example, if the
cellulosic fibers of the aqueous cellulosic furnish are flocculated
effectively to larger flocs, retention of, for example, fiber fines and
filler is generally good and can result in a porous structure yielding
generally good drainage; however, formation is poor. In this light,
conventional practice has resulted in those skilled in the art selecting
one or more additives to improve the production of paper or paperboard
according to the parameters that are most important to achieve.
Alternatively, if the cellulosic fibers are flocculated to a lesser
degree, drainage and retention are less satisfactory; however, formation
is improved. Further, drainage and retention are often in conflict with
each other when, for example, increased production of paper or paperboard
is desired over the need for retention of, such as for example, fillers
and the like.
Retention is believed to be a function of different mechanisms such as
filtration by mechanical entrainment, electrostatic attraction and
bridging between aqueous cellulosic fibers and filler. Because both
cellulose and many common fillers are electronegative, they are mutually
repellant and, in the absence of a retention aid, the only factor tending
to enhance retention is mechanical entrainment.
Drainage relates to the rate at which free water is released from a sheet
as it is being formed. Thus, it will be appreciated that drainage aids
improve the overall efficiency of dewatering in the production of paper or
paperboard.
Formation relates to the formation of the paper or paperboard sheet
produced from the papermaking process. Formation is generally evaluated by
the variance in light transmission within a paper sheet. A high variance
is indicative of poor formation. It is generally well known by those
skilled in the art that as the retention level increases, the level of
formation generally decreases from good formation to poor formation.
A variety of compositions and processes have been proposed to improve
retention, drainage, or formation to improve the papermaking process.
U.S. Pat. No. 4,913,775 (Langley et al) discloses a process of making paper
or paper board comprising passing an aqueous cellulosic suspension through
one or more shear stages, draining the suspension to form a sheet and
drying the sheet wherein an improved combination of retention, drainage,
drying and formation is achieved by adding to the suspension an excess of
high molecular weight linear synthetic cationic polymer before shearing
the suspension and adding bentonite after shearing.
U.S. Pat. No. 4,643,801 (Johnson) discloses a paper making process in which
paper making stock containing a sufficient amount of cellulosic pulp is
formed into a sheet and dried and to which is added prior to formation of
the sheet a coacervate binder comprising a cationic starch, a high
molecular weight anionic polymer and a dispersed silica.
U.S. Pat. No. 4,388,150 (Sunden et al) discloses a paper making process and
an improved cellulosic paper product. This patent states that a paper
making process is provided in which an aqueous papermaking stock
containing a sufficient amount of cellulosic pulp is formed and dried,
wherein the improvement comprises providing in the stock prior to the
formation of the sheet a binder comprising colloidal silica acid having an
average particle size less than 20 nanometers and cationic starch. This
patent states that the cationic starch and the colloidal silica acid are
admixed with each other in the presence of cellulosic fiber to form a
complex of cationic starch and colloidal silica acid which serves as a
binder for the cellulosic fibers.
U.S. Pat. No. 5,098,520 (Begala) discloses a process in which paper or
paperboard is made and wherein drainage and/or retention is improved
including forming an aqueous cellulosic papermaking slurry that is subject
to one or more shear stages, adding sequentially to the slurry a mineral
filler, a high molecular weight cationic polymer that is a
(meth)acrylamide polymer, and a medium molecular weight anionic polymer.
U.S. Pat. No. 5,185,062 (Begala) discloses a process in which paper or
paperboard is made and wherein drainage and/or retention is improved
including forming an aqueous cellulosic papermaking slurry that is subject
to one or more shear stages, adding sequentially to the slurry a
(meth)acrylamide polymer and a medium molecular weight anionic polymer
having at least 20 mole percent ionizable mer units including at least 10
mole percent sulfonate-containing mer units.
U.S. Pat. No. 4,313,790 (Pelton et al) discloses a papermaking process for
simultaneously increasing the retention of fines, fillers and pigments and
decreasing the deposition of pitch on the papermaking apparatus comprising
adding to an aqueous wood slurry a poly(oxyethylene) and a kraft lignin
product.
U.S. Pat. No. 4,347,100 (Brucato) discloses a method of producing paper
having improved bursting strength from mechanical or thermomechanical pulp
comprising defibering wet wood by mechanical attrition to form mechanical
or thermomechanical pulp, processing the pulp to form a furnish,
incorporating into the pulp at an elevated temperature and pressure an
anionic organic polyelectrolyte or polymer to improve bursting strength,
and adding to the furnish a cationic organic polyelectrolyte or polymer.
The patent states that the anionic organic polyelectrolyte or polymer
causes dispersion of lignin and retards deposition of lignin to improve
the bursting strength. This patent discloses that the anionic
polyelectrolyte or polymer must be incorporated into the pulp by cooking
at elevated temperature and pressure before or during the refining or
defibering stage to achieve the desired end result of paper having
improved bursting strength. This patent states that the anionic organic
polyelectrolyte or polymer is a polymeric sulfonate.
U.S. Pat. No. 4,606,790 (Youngs et al) discloses a method of preparing an
electrically conductive multi-ply structure for intercepting and
dissipating electrostatic charges and discharges comprising forming in a
mixing vessel an aqueous slurry consisting essentially of a fibrous
material, particles of an inorganic electrically conductive substance and
an electroconductive polymer dispersant, dispersing the particles in the
mixing vessel in the presence of the fibrous material and the polymer
dispersant, forming a plurality of separate aqueous slurries consisting
essentially of a non-conductive fibrous material, transporting the slurry
containing the particles of the conductive substance from the mixing
vessel to a paper forming machine, and adding a retention aid polymer to
the slurry. This patent states that the electroconductive polymer
dispersant is a cationic amine-substituted polymethacrylate or an anionic
alkali metal polyacrylate or lignosulfonate.
U.S. Pat. No. 4,145,246 (Goheen et al) discloses a linerboard composition
and a process for producing the linerboard composition having a percent
mullen of at least 80%, including a replacement quantity of
sulfite-modified thermomechanical pulp. This patent states that the
process for producing a linerboard composition comprises imparting
mechanical attrition forces to undefibered lignocellulose which has been
subjected to elevated temperature and pressure, adding a sulfite chemical
to the lignocellulose prior to, during, or subsequent to the initial
mechanical attrition, subjecting the sulfite-treated lignocellulose to a
second mechanical attrition step, forming an aqueous linerboard furnish
including at least 25% by weight of the sulfite-modified thermomechanical
pulp, depositing the furnish on a foraminous surface to produce a wet
linerboard web, and drying the linerboard web.
U.S. Pat. No. 3,180,787 (Adams) discloses a method for increasing the
flexural strength of paper comprising adding a water soluble
lignosulfonate salt to a water slurry of cellulose pulp, adding a
polyethylene polyamine thereby precipitating insoluble polyethylene
polyamine lignosulfonate, and forming the pulp fibers with adhered
insoluble precipitate into a continuous paper web.
U.S. Pat. No. 4,772,332 (Nemeh et al) discloses a heat stabilized dispersed
slurry of particles of chemically bulked hydrous kaolin clay pigment for
use in coating or filling paper and method for preparing same. The patent
states that the process comprises preparing a fluid aqueous suspension of
kaolin clay, adding thereto a cationic polyelectrolyte for flocculating
the clay suspension, filtering the suspension, washing the filtered clay,
adding to the filtered clay a dispersant that is a combination of a
polyacrylate salt, an anionic water soluble lignosulfonate and a
water-soluble naphthalene sulfonate formaldehyde complex to provide a
fluid suspension of bulked clay free from a phosphate dispersant.
U.S. Pat. No. 3,985,937 (Fife) discloses a corrugating medium laminating
adhesive comprising a polymer latex emulsion adhesive containing polyvinyl
acetate homopolymers and styrenebutadiene polymers admixed in water with a
clay, a paraffin wax, a polyalkylene glycol wetting agent and a
lignosulfonate dispersant.
U.S. Pat. No. 3,849,184 (Roberts) discloses a coated paperboard containing
paperboard consisting of at least one ply consisting essentially of
cellulosic fibrous materials, and a coating on at least one surface
thereof comprising a water soluble lignosulfonate salt and a non-reactive
hydrophobic waxy material.
U.S. Pat. No. 3,758,377 (Fife) discloses a process for the preparation of a
paper sheet by treating the cellulosic fibers in an aqueous slurry with a
mixture of a lignosulfonate and an isoprene resin stabilized with an
urea-formaldehyde resin.
TAPPI, Papermakers Conference Proceedings, Book 1, pp. 115-186, (Atlanta,
Georgia--Apr. 18-21, 1993) discloses microparticle systems such as for
example, a system having a cationic starch or cationic polyacrylamide or
anionic polymers and an anionic silica colloid or bentonite or alumina sol
for improving dewatering, retention, formation and dry strength.
TAPPI, The Journal Of The Technical Association Of The Pulp And Paper
Industry, Vol. 63, No. 6, pp. 63-66 (June, 1980) authorized by C. H. Tay,
discloses that water soluble substances such as lignosulfonate originating
from wood constituents deactivate cationic polyelectrolytes used for
filler retention.
Colloids And Surfaces, Vol. 64, pp. 223-234 (1992), co-authored by P. Li
and R. Pelton, discloses that cationic poly (diallyldimethyl ammonium
chloride) increased the efficiency of the displacement washing of aqueous
kraft lignin from a bed of glass beads. This publication states that
improved washing results when the poly (diallyldimethyl ammonium chloride)
concentration is high enough to form an insoluble complex with lignin.
TAPPI, Contaminant Problems And Strategies In Wastepaper Recycling, Seminar
Notes (Madison, Wis.) pp. 91-96 (Apr. 24-26, 1989), authored by T. H.
Wegner, discloses that pulping liquors, such as kraft lignin and
saponified extractives, used in papermaking are a major source of white
water contaminants and adversely affect the performance of a cationic
polyacrylamide used as a drainage aid. More specifically, this publication
states that kraft lignin completely negated the effectiveness of
polyacrylamide as a drainage aid, and that fines retention was also
adversely affected.
EUCEPA/ATICELCA, Devt. & Trends in Sci. & Technol. of Pulp & Pmkg., Vol. 2,
Paper No. 31, pp. 1-22 (Oct. 6-10, 1986), co-authored by D. Ahrabi, L.
Odberg and G. Strom, discloses that in closed white water systems anionic
polymers such as, for example, lignin and lignosulfonate, interfere
strongly with cationic polymers that are used to improve retention and
drainage on the paper machine.
It will be appreciated by those skilled in the art that the above mentioned
background technical publications teach against the addition of lignin or
modified lignin to paper furnishes having a cationic component. Therefore,
it will be understood by those skilled in the art that applicants have
discovered unexpectedly that the composition and process of the instant
invention comprising adding a modified lignin to an aqueous cellulosic
furnish having a high molecular weight cationic polymer component results
in producing paper or paperboard having improved drainage, retention and
formation properties that are superior to results of others previously
achieved.
In spite of this background material, there remains a very real and
substantial need for a composition and process for making improved paper
or paperboard in the areas of drainage, retention, or formation, and
combinations thereof.
BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 compares the effect on formation between the use of a cationic
polymer alone, and cationic polymer and a modified lignin at varying
amounts and shear rates.
FIG. 2 compares the effect on retention between the use of a cationic
polymer alone, and cationic polymer and a modified lignin at varying
amounts and shear rates.
FIG. 3 compares the effect on opacity between the use of a cationic polymer
alone, and cationic polymer and a modified lignin at varying amounts and
shear rates.
FIG. 4 compares the effect on brightness between the use of a cationic
polymer alone, and cationic polymer and a modified lignin at varying
amounts and shear rates.
FIG. 5 compares the effect on drainage time between the use of a cationic
polymer alone, and cationic polymer and a modified lignin at varying
amounts and shear rates.
SUMMARY OF THE INVENTION
The present invention has met the above-described needs. The present
invention provides a process in which paper or paperboard having
unexpectedly improved properties is made by forming an aqueous cellulosic
paper furnish, adding to the furnish an effective amount, based on the dry
weight of the solids of the furnish, of (A) a high molecular weight
cationic polymer and (B) a modified lignin, draining the slurry to form a
sheet and drying the sheet. The weight ratio of the cationic polymer (A)
to the modified lignin (B) is from about 10:1 to 1:10, on an active basis,
more preferably from about 5:1 to 1:5, and most preferably from about 3:1
to 1:3.
In a preferred embodiment of this invention, the process as described
herein is provided wherein the modified lignin is selected from the group
consisting of sulfonated lignin, carboxylated lignin, oxidized lignin, and
salts thereof. In another preferred embodiment of this invention, the
process wherein the sulfonated lignin has a degree of sulfonation of from
about 0.1 to 10 moles of sulfonic acid groups per 1000 unit weight of the
lignin is included.
In yet another embodiment of this invention, paper or paperboard produced
by the process of this invention is provided wherein the paper or
paperboard has improved properties in the areas of retention, drainage or
formation, and combinations thereof.
Another embodiment of this invention provides a process in which paper or
paperboard is made by forming an aqueous cellulosic paper furnish
comprising subjecting the furnish to one or more shear stages, adding to
the furnish prior to at least one of the shear stages a high molecular
weight cationic polymer (A), adding to the furnish subsequent to the
addition of the cationic polymer and at least one shear stage subsequent
there to, a modified lignin (B), draining the furnish to form a sheet and
drying the sheet. The weight ratio of the cationic polymer (A) to the
modified lignin (B) is from about 10:1 to 1:10, on an active basis, more
preferably from about 5:1 to 1:5, and most preferably from about 3:1 to
1:3.
Another embodiment of this invention provides a composition comprising (a)
an aqueous cellulosic furnish, (b) a high molecular weight cationic
polymer, and (c) a modified lignin wherein the ratio of the cationic
polymer to the modified lignin is from about 10:1 to 1:10, on an active
basis, more preferably from about 5:1 to 1:5 and most preferably from
about 3:1 to 1:3.
In another embodiment of this invention, paper or paperboard is provided
comprising the composition of this invention.
DETAILED DESCRIPTION OF THE INVENTION
The instant invention is directed to a process in which paper or paperboard
having improved properties is made and the composition for improving
drainage, retention, or formation, and combinations thereof in the
manufacture of paper or paperboard.
As used herein, the term "furnish" refers to all paper and paperboard
furnishes based on, for example, but not limited to, mechanical pulp,
semi-bleached kraft pulp, unbleached kraft pulp and/or unbleached sulfite
pulp.
As used herein, the term "active basis" means a concentration of additive
based on the solids in the stock solution.
As used herein, the term "effective amount" refers to that amount of the
composition necessary to bring about a desired result, such as, for
example, the amount needed to improve drainage, retention, or formation,
and combinations thereof in the manufacture of paper or paperboard.
The present invention provides a composition comprising (a) an aqueous
cellulosic furnish, (b) a high molecular weight cationic polymer, and (c)
a modified lignin, wherein the ratio of the cationic polymer to the
modified lignin is from about 10:1 to 1:10, on an active basis. The
modified lignin used in the instant invention can be derived from the
kraft pulping process and may be, for example, but not limited to,
fractionated lignins in terms of molecular weight, purified or may be used
in either the protonated or salt forms. In a preferred embodiment of this
invention, the modified lignin is selected from the group consisting of
sulfonated lignin, carboxylated lignin, oxidized lignin and salts thereof.
The modified lignin used in the instant invention can be derived from the
sulfite pulping process for example, but not limited to, a lignin adduct
copolymerized with formaldehyde resulting in a modified lignin having a
weight average molecular weight greater than about 50,000 such as for
example Dynasperse A commercially available from Lignotech USA, Inc.,
Greenwich, Conn.
In a most preferred embodiment of this invention, the composition as
described herein includes a sulfonated lignin that has a degree of
sulfonation of from about 0.1 to 10 moles of sulfonic acid groups per 1000
unit weight of the lignin.
In a preferred embodiment of this invention, the composition as described
herein includes wherein the sulfonated lignin has a weight average
molecular weight of greater than about 2,500, more preferably greater than
about 10,000, and most preferably greater than about 50,000.
The composition of the instant invention, as described herein, preferably
includes wherein the weight ratio of the cationic polymer to the modified
lignin is from about 5:1 to 1:5 and most preferably is from about 3:1 to
1:3.
In another embodiment of this invention, the cationic polymer of the
instant composition is derived from at least one cationic monomer selected
from the group consisting of a quaternary dialkyldiallyl ammonium monomer,
methacryloyloxyethyl trimethyl ammonium chloride, methacryloyloxyethyl
trimethyl ammonium methosulfate, acrylamido propyl trimethyl ammonium
chloride, methacrylamido propyl trimethyl ammonium chloride,
acryloyloxyethyl trimethyl ammonium chloride, quaternized derivatives of
N, N-dimethyl amino ethyl methacrylate, dimethyl amino ethyl acrylate,
diethyl amino ethyl acrylate, dibutyl amino ethyl methacrylate, dimethyl
amino methyl acrylate, dimethyl amino methyl methacrylate, diethyl amino
propyl acrylate, diethyl amino propyl methacrylate, acryloyloxyethyl
trimethyl ammonium methosulfate, amino methylated polyacrylamide, and
combinations thereof.
As used herein, the term "dialkyldiallyl ammonium monomer" refers to any
water soluble monomer of the formula DADAAX.sup.- !, which represents
dialkyldiallyl ammonium X.sup.-, wherein each alkyl is independently
selected from an alkyl group of from about 1 to 18 carbon atoms in length,
and preferably from about 1 to 4 carbon atoms, and wherein X.sup.- is any
suitable counterion. Preferably, the counterions are selected from the
group consisting of conjugate bases of acids having an ionization greater
than 10.sup.-13, and more preferably selected from the group consisting of
a halide, hydroxide, nitrate, acetate, hydrogen sulfate, methyl sulfate,
and primary phosphates. The halide may be any halide, and more preferably
is selected from the group consisting of fluoride, bromide and chloride.
Preferably, the quaternary dialkyldiallyl ammonium halide monomer is
selected from the group consisting of dimethyl diallyl ammonium chloride,
diethyl diallyl ammonium chloride, dimethyl diallyl ammonium bromide, and
diethyl diallyl ammonium bromide.
It is noted that the cationic polymer component of the composition of this
invention may contain one or more other mer units without departing from
the concept of this invention. Copolymers, terpolymers, etc., such as, for
example, polymers comprising dimethyl diallyl ammonium chloride and
acrylamide may be employed as the cationic polymer component of the
composition of the instant invention. In a preferred embodiment of this
invention, the cationic polymer is a copolymer derived from at least one
of the hereinbefore mentioned cationic monomers and of at least one of a
nonionic monomer selected from the group consisting of acrylamide,
methacrylamide, diacetone acrylamide, and N, N-dimethyl acrylamide,
wherein the ratio of the cationic monomer to the nonionic monomer is from
about 99:1 to 1:99. Preferably, the weight ratio of the cationic monomer
to the nonionic monomer is from about 3:97 to 60:40 and most preferably is
from about 10:90 to 23:77. It will be appreciated by those skilled in the
art that the ratio of mer units in such copolymers generally is determined
by the quantity of cationic units necessary in the instant composition to
impart the desired drainage, retention and formation, or combinations
thereof for the manufacture of a particular paper or paperboard. Further,
additional cationic mer units may be present.
It will be understood by those skilled in the art that the cationic polymer
component and the modified lignin component of the composition of this
invention, as described herein, are water soluble or water dispersible.
It will be appreciated by those skilled in the art that when employing
diacetone acrylamide as the nonionic monomer, it is preferable to employ
less than about 35 weight percent of diacetone acrylamide for achieving
adequate water solubility. It will be understood that employing more than
35 weight percent of diacetone acrylamide results in reduced water
solubility.
An effective amount of the composition of the instant invention should be
employed. It will be appreciated by those skilled in the art that the
dosage of the composition added to the aqueous cellulosic furnish being
treated is dependent on the degree of retention, drainage and formation
desired. At least about 0.1 pounds per ton based on the dry weight of
solids in the furnish should be added.
The high molecular weight cationic polymer component of the instant
composition has a weight average molecular weight above about 300,000 and
preferably above about 1,000,000. Most preferably, the high molecular
weight cationic polymer component of the instant composition has a weight
average molecular weight above about 2,000,000.
The composition of the instant invention can generally be successfully
added to aqueous cellulosic furnishes over the entire pH range customarily
employed in the papermaking process. Preferably, the composition of the
instant invention is added to aqueous cellulosic furnishes having a pH
from about 3 to 10. Therefore, it will be appreciated by those skilled in
the art that the composition of the instant invention may be added to
aqueous cellulosic paper furnishes that are acid, alkaline, or neutral in
character. It will be understood by those skilled in the art that
generally an acid furnish has a pH range from about 3.0 to 5.5, an
alkaline furnish has a pH range from about 7.0 to greater than about 10.0,
and a neutral furnish has a pH range of from about 5.5 to 7.0.
In another embodiment of this invention, a process is provided for in which
paper or paperboard having improved properties is made by forming an
aqueous cellulosic paper furnish which comprises adding to the furnish an
effective amount, based on the dry weight of the solids of the furnish, of
(A) a high molecular weight cationic polymer, as hereinbefore described,
and (B) a modified lignin, as hereinbefore described, draining the furnish
to form a sheet and drying the sheet, wherein the weight ratio of the
cationic polymer (A) to the modified lignin (B) is from about 10:1 to
1:10, on an active basis, preferably from about 5:1 to 1:5, and most
preferably about 3:1 to 1:3. In another embodiment of the instant
invention, the process, as hereinbefore described, includes wherein the
modified lignin is selected from the group consisting of sulfonated
lignin, carboxylated lignin, oxidized lignin and salts thereof.
Preferably, the process includes wherein the sulfonated lignin has a
degree of sulfonation of from about 0.1 to 10 moles of sulfonic acid
groups per 1000 unit weight of the lignin.
In another embodiment of this invention, the process, as hereinbefore
described, includes wherein the sulfonated lignin has a weight average
molecular weight greater than about 2,500, preferably greater than about
10,000, and most preferably greater than about 50,000.
In a further embodiment of this invention the process includes wherein the
cationic polymer is derived from at least one cationic monomer, as
hereinbefore described. More preferably the process of this invention, as
hereinbefore described includes wherein the cationic polymer is a
copolymer derived from at least one of the cationic monomers and of at
least one of the nonionic monomers as hereinbefore described. The instant
process includes wherein the weight ratio of the cationic monomer to the
nonionic monomer is from about 99:1 to 1:99, preferably from about 3:97 to
60:40, and most preferably from about 10:90 to 23:77.
The process of the instant invention includes adding an effective amount of
the composition to the aqueous cellulosic paper furnish. It will be
appreciated by those skilled in the art that the dosage of the composition
added to the aqueous cellulosic paper furnish is dependent on the
drainage, retention and formation parameters desired. At least about 0.1
pounds per ton of the cationic polymer should be added to the furnish
based on the dry weight of solids in the furnish. The instant process
includes wherein at least about 0.1 pounds of the modified lignin is added
to the furnish based on the dry weight of solids in the furnish.
It is believed that the pH of the aqueous cellulosic paper furnish is
unimportant as the instant composition is effective in treating aqueous
cellulosic paper furnishes having a wide range of alkaline, neutral and
acidic pH's. Preferably, the process of the instant invention includes
wherein the aqueous cellulosic paper furnish has a pH from about 3 to 10.
In another embodiment of the instant invention, a process is provided in
which paper or paperboard is made by forming an aqueous cellulosic paper
furnish comprising subjecting the furnish to one or more shear stages,
adding to the furnish prior to at least one of the shear stages a high
molecular weight cationic polymer, as hereinbefore described, adding to
the furnish subsequent to the addition of the cationic polymer and at
least one shear stage subsequent thereto, a modified lignin, as
hereinbefore described, draining the furnish to form a sheet and drying
the sheet, wherein the weight ratio of the cationic polymer to the
modified lignin is from about 10:1 to 1:10, on an active basis, preferably
from about 5:1 to 1:5, and most preferably from about 3:1 to 1:3.
A further embodiment of the instant invention provides a process, as
hereinbefore described, including the cationic polymer derived from at
least one cationic monomer, as hereinbefore described, and combinations
thereof. Preferably, the instant invention includes the process wherein
the cationic polymer is a copolymer derived from at least one of the
cationic monomers, as hereinbefore described, and of at least one of the
nonionic monomers, as hereinbefore described. The weight ratio of the
cationic monomer to the nonionic monomer is from about 99:1 to 1:99.
Another embodiment of this invention includes paper or paperboard produced
by the process of the instant invention, as hereinbefore described,
wherein the paper or paperboard has improved properties in the areas of
retention, drainage, or formation and combinations thereof.
It will be appreciated by those skilled in the art that the composition and
process of this invention may be employed in conjunction with other
additives used during the manufacture of paper or paperboard such as, but
not limited to, fillers, pigments, binders, and strength aids.
The cationic polymers of the instant composition may be prepared using any
conventional polymerization technique that is well known by those skilled
in the art.
The composition of the instant invention may be added to the paper furnish
as hereinbefore described at any convenient point prior to sheet
formation. It will be appreciated by those skilled in the art that the
exact points of addition are mill specific. Preferably, the composition of
this invention is added to thin diluted aqueous cellulosic paper furnish.
Any suitable method of addition known in the art can be utilized. A
preferred method of addition includes adequate dilution to accomplish
dispersion of the composition throughout the furnish.
It will be appreciated by those skilled in the art that the process and the
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