Note: Descriptions are shown in the official language in which they were submitted.
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POLYETHYLENE OXIDE TREATMENT FOR DRAINAGE AGENTS
AND DRY STRENGTH AGENTS
[000I] This application claims the benefit of US provisional application
number
61/864,262, filed 09 August 2013, the entire contents of which are hereby
incorporated by
reference.
BACKGROUND
[0002] Paper and paperboard are produced from an aqueous slurry of
cellulosic fiber,
depositing this slurry on a moving papermaking wire or fabric, and forming a
sheet from the
solid components of the slurry by draining the water. This sequence is
followed by pressing
and drying the sheet to further remove water.
[0003] Drainage or dewatering of the fibrous slurry on the papermaking wire
or fabric is
often the limiting step in achieving faster paper machine speeds. Improved
dewatering can
also result in a drier sheet in the press and dryer sections, resulting in
reduced energy
consumption. Chemicals are often added to the fibrous slurry before it reaches
the
papermalcing wire or fabric to improve drainage/dewatering and solids
retention; these
chemicals are called retention and/or drainage aids.
[0004] Dry strength additives are used in paper mill to increase the
strength of paper. It
increases the strength of paper by increasing internal bond formation.
Moreover dry strength
additives improve bust strength, tear strength, wax pick values, folding
endurance, stiffness,
machine runnability, increase levels of paper filler uses etc. Dry strength
additives also
reduced linting and dusting.
[0005] Retention and drainage aids have reduced efficacy in some furnish
substrates
which contain high levels of soluble organics and salts. Two such examples of
these
furnishes are neutral sulfite semi chemical (NSSC) and kraft virgin
linerboard, where high
levels of soluble lignin and other organic materials containing a high anionic
charge are
present. These highly anionic materials neutralize the charge on the
conventional retention
and drainage aids, significantly reducing their effectiveness.
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DETAILED DESCRIPTION OF INVENTION
[00061 It has been discovered that treatment of cellulosic furnish with a
polyethylene
oxide homo polymer or copolymer ("PEO") will improve the performance of the
drainage or
strength agents in cellulosic furnish that contain high levels of soluble
lignin where the
drainage or strength agents are not typically active. Soluble lignin levels in
these cellulosic
furnishes range from 25 parts-per-million (ppm) up to 500 ppm.
[0007] Without wishing to be bound by theory it is believed that the PEO
reacts with the
excess lignin and other excess anionic materials in the cellulosic furnish
thereby allowing
the drainage or strength agent to work without be hindering by reacting with
the undesirable
materials.
[0008] Molecular weights (Mw) are viscosity average molecular weight as
determined
from intrinsic viscosity determinations.
[0009] The PEO can be a homo-polymer of ethylene oxide, or a copolymer of
ethylene
oxide. Suitable comonomers include propylene oxide or butylene oxide. A
hornopolymer of
polyethylene oxide is the most preferred. Additional suitable comonomers used
to make the
PEO copolymer can be cationic, anionic, non-ionic or hydrophobic monomers, and
any
mixture thereof. The molecular weight of the PEO homo-polymer or co-polymer
can range
from 1000 daltons up to 25,000,000 daltons or 100,000 to 15,000,000 daltons or
1,000,000
to 10,000,000 daltons. Examples of ethylene oxide containing homo polymers or
copolymers are UcarflocTm 300, 302, 304, and 309 (available from Dow Chemical,
Midland,
MD.
[0010] The feed point of the PEO treatment can include the thick stock,
thin stock, white
water, or process water. The PEO treatment can be added at the blend chest,
machine chest,
fan pump, cleaners, centriscreen, save-all, white water tray and white water
silo.
[0011] The PEO treatment dosage can range from 0.01 pounds (lbs) to 10 lbs
of PEO
polymer per ton of furnish solids. The dosage can also be based upon the
furnish volume,
ranging from 0.01parts-per-million (ppm) to 10,000 ppm of PEO per volume of
furnish or
substrate water. The PEO is generally supplied as a dry powder or granular
product, where
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it is dissolved at the application site. It can also be supplied to the end
user as a slurry or
dispersion for ease of use, where it can be diluted and fed into the process
stream.
[0012] The drainage or strength agents, which will function due to the
PEO treatment,
are generally water-soluble or water-dispersible synthetic polymers,
"synthetic polymer".
The synthetic polymers can be nonionic polymers, cationic copolymers or
anionic
copolymers.
[0013] The nonionic monomers used to make the synthetic polymer
include, but are not
limited to, acrylamide; methacrylamide; N-alkylacrylamides, such as N-
methylacrylamide; N,N-dialkylacrylamide, such as N,N-climethylacrylamide;
methyl
methacrylate; methyl acrylate; acrylonitrile; N-vinyl methylacetamide; N-
vinylformamide;
N-vinylmethyl formamide; ; vinyl acetate; N-vinyl pyrrolidone and mixtures of
any of the
foregoing. The invention contemplates that other types of nonionic monomer can
be used.
More than one kind of non-ionic monomer can be used to make the synthetic
polymer.
Preferable nonionic monomers used are acrylamide; methacrylamide, N-
vinylformamide.
[0014] The cationic monomers used to make the synthetic polymer
include, but are not
limited to, cationic ethylenic ally unsaturated monomers such as the
diallyldialkylanarnonium
halides, such as diallyldirnethylammonium chloride; the (meth)acrylates of
dialkylaminoalkyl compounds, such as dimethylaminoethyl (meth)acrylate,
diethylaminoethyl (meth)acrylate, dimethyl aminopropyl (meth)acrylate, 2-
hydroxydimethyl
aminopropyl (meth)acrylate, aminoethyl (meth)acrylate, and the salts and
quaternaries
thereof; the N,N-dialkylaminoalkyl(meth)acrylamides, such as N,N-
dimethylaminoethylacrylamide, and the salt and quaternaries thereof and
mixtures of the
foregoing. More than one kind of non-ionic monomer can be used to make the
synthetic
polymer. Most preferred are diallyldimethylammonium chloride and
dimethylaminoethyl
(meth) acrylate and the salt and quaternaries thereof and mixtures of the
foregoing.
[0015] Poly(vinylamine) is also a suitable cationic synthetic polymer
for the
invention. The polyvinyl amine can he a homopolyrner or a copolymer. One
method of
producing a polyvinylarnine polymer is by polymerization of the monomer(s)
followed by
hydrolysis. The level of hydrolysis can be expressed as"% hydrolysis" or
"hydroIysis%" on
a molar basis. A hydrolyzed polymer can thus be described by as "%
hydrolyzed."
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Moreover the level of hydrolysis can be approximated. For the purposes of
applicants'
invention, a poly(vinylamine) that is referred to as "50% hydrolyzed" means
from 40% to
60% hydrolyzed. Likewise, a poly(vinylamine) that is about 100% hydrolyzed
means from
80% to 100% hydrolyzed. The hydrolysis reaction results in the conversion of
some or all of
the monomer(s) to amines, as controlling the hydrolysis reaction can vary the
resultant
percentage of monomers having amine functionality.
[0016] Examples of monomers used to make a poly(vinylamine) include,
but are not
limited to, N-vinylformamide, N-vinyl methyl formamide, N-vinylphthalimide, N-
vinylsuccinimide, N-vinyl-t-butylcarbamate, N-vinylacetamide, and mixtures of
any of the
foregoing. Most preferred are polymers prepared by the hydrolysis of N-
vinylformamide.
b the case of copolymers, nonionic monomers, such as those described above,
are the
preferred comonomers. Alternatively, poly(vinylamine) can be prepared by the
derivatization of a polymer. Examples of this process include, but are not
limited to, the
Hofmann reaction of polyacrylamide. It is contemplated that other synthetic
routes to a
poly(vinylamine) or polyamine can be utilized.
[0017] The molar percentage of nonionic monomer to cationic monomers
may fall
within the range of about 100:1 to 1:100, or 80:20 to 20 to 80, or 75:25:
25:75 or 40:60 to
60:40, where the molar percentages of nonionic monomers to cationic monomers
must add
up to 100%. It is to be understood that more than one kind of nonionic or
cationic monomer
may be present in synthetic polymer.
[0018] The anionic monomers used to make the synthetic polymer include,
but are not
limited to, the free acids and salts of acrylic acid; methacrylic acid; maleic
acid; itaconic
acid; acrylamidoglycolic acid; 2-acrylamido-2-methy1-1-propanesulfonic acid; 3-
allyloxy-2-
hydroxy-1-propanesulfonic acid; styrenesulfonic acid; vinylsulfonic acid;
vinylphosphonic
acid; 2-acrylarnido-2-methylpropane phosphonic acid; and mixtures of any of
the
foregoing. Most common are the free acids or salts of acrylic acid,
methacrylic acid,
and 2-acrylamido-2-methyl-1-propanesulfonic acid. When a salt form of an acid
is used to
make an anionic polymer, the salt is selected from Nat, K+ or N1-14. More than
one kind of
anionic monomer can be used to make the synthetic polymer.
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[0019] The molar percentage of nonionic monomers to anionic
monomers may fall
within the range of about 100: Ito 1:100, or 90:10 to 30:70, or 40:60 to
70:30, where the
molar percentages of nonionic monomers to anionic monomers must add up to
100%.
It is to be understood that more than one kind of nonionic may be present. It
is also to be
understood that more than one kind of cationic monomer may be present.
[0020] The synthetic water-soluble or water-dispersible polymers
can also be
modified to impart additional properties to the synthetic polymer or to modify
the
synthetic polymer structure. Polymerization of the monomers can occur in the
presence of a
polyfunctional agent, or the polyfunctional agent can be utilized to treat the
polymer post-
polymerization. Useful polyfunctional agents comprise compounds having either
at least two
double bounds, a double bond and a reactive group, or two reactive groups.
Illustrative of
those containing at least two double bounds are N,N- methylenebisacrylamide;
N,N-
methylenebismethacrylamide; polyethyleneglycol diacrylate; polyethyleneglycol
dimethacrylate; N-vinyl acrylarnide; divinylbenzene; triallylammonium salts,
and N-
methylallylacrylamide. Polyfunctional branching agents containing at least one
double bond
and at least one reactive group include glycidyl acrylate; glycidyl
methacrylate; acrolein; and
methylolacrylamide. Polyfunctional branching agents containing at least two
reactive
groups include dialdehydes, such as glyoxal; and diepoxy compounds;
epichlorohydtin.
[0021] Examples of synthetic polymers used in the invention
include but are not limited
to polyvinylamine, glyoxylated cationic polyacrylamide, and cationic
polyacrylamide.
Preferred are 100% hydrolyzed polyvinylanaine, 50% hydrolyzed polyvinylamine
and
cationic polyacrylamide containing at least 10 mole % cationic monomer. One
example
would be cationic polyacrylamide containing at least 10 mole %
diallyldimethylammonium chloride or 10 mole % dinnethylaminoethyl
(meth)acrylate.
Additional useful polymers of the present invention include PerformTM products
such as SP
7200 (anionic polyacrylamide polymer), (Hercules Incorporated, Wilmington DE.
HercobondTm 6350 (polyvinylamine copolymer polymer), HercohondTM 6363
(polyvinylamine copolymer), HercobondTm 6950 (polyvinylamine copolymer),
HercobondTM 1307 (modified cationic polyacrylamide), Perfomirm PC 8181
(cationic
polyacrylamide), Perforrem PC 8179 (cationic polyacrylamide).
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[0022] The molecular weight of the non-ionic, cationic, or anionic polymers
can range
from 10,000 to 50,000,000 daltons, or 1,000,000 to 25,000,000 daltons, or
5,000000 to
20,000,000 daltons.
[0023] The treatment is effectuated by adding the PEO to the cellulosic
furnish (slurry)
at a feed point in the papermaking system and adding the water-soluble or
water-dispersible
synthetic polymers to the treated slurry. The PEO and the synthetic polymers
can be added
at the same feed point or different feed points. The PEO and the synthetic
polymers can be
added simultaneously, individual or as a blend. In one embodiment the PEO and
the
synthetic polymers can be added in sequence to the papermaking system. The
slurry is then
drained on the papermaking wire to dewater the fibrous slurry and to form a
sheet.
Improved drainage is observed when the PEO and the synthetic polymers are used
in
conjunction with one another.
[0024] Less synthetic polymer can be used while still maintaining the same
performance
level (drainage) when the PEO is used in conjunction with the synthetic
polymer.
[0025] The feed point of the synthetic polymer can include the thick stock
or thin stock.
Potential addition points of the synthetic polymer can include the blend
chest, machine
chest, fan pump, cleaners, and before or after the centriscreen. The synthetic
polymer
dosage can range from 0.01 lbs to 10 lbs. of active polymer per ton of furnish
solids or 0.01
to 5 , or 0.05 to 5, or 0.1 to 2 lbs. of polymer per ton of furnish solids.
The synthetic
polymer can be manufactured and supplied to the end user as a dry or granular
powder, an
aqueous solution or dispersion, or an inverse emulsion.
[0026] The weight ratio of the PEO to synthetic water-soluble polymer can
range from
100:1 to 1:100 or 80:20 to 20: 80 or 50:50 to 10:90.
[0027] Suitable cellulosic furnish or fiber pulps for the method of the
invention include
conventional papermaking stock such as traditional chemical pulp. For
instance, bleached
and unbleached sulfate pulp and sulfite pulp, mechanical pulp such as
groundwood, thermo-
mechanical pulp, chemi-thermomechmical pulp, recycled pulp such as old
corrugated
containers, newsprint, office waste, magazine paper and other non-deinked
waste, deinked
waste, and mixtures thereof, may be used. The pH of the cellulosic furnish or
slurry may
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range from 4 to 8.
EXAMPLES
[00281 A series of drainage experiments were conducted utilizing a paper
machine pulp
slurry comprising neutral sulfite semi-chemical (NSSC), virgin kraft, and old
corrugated
containers (OCC). The drainage performance of the inventive process was
evaluated using a
vacuum test, where a Buechner funnel is affixed atop a graduated cylinder. 500
milliliters
(m's) of the pulp slurry is mixed in a beaker using a mechanical overhead
mixer, and the
noted polymer treatment are added sequentially. The time required to collect
the noted
amount of filtrate is recorded, where a lower time is representative of the
desired faster
drainage. The PEO is a high molecular weight (7 million) homopolymer and
FlercobondTM
6950 is a cationic modified polyamine water soluble polymer, (Hercules,
Wilmington DE).
The data in Table I demonstrated no drainage response with the HercobondTM
6950
compared to the untreated system. A drainage response is noted with the PEO. A
high
drainage response is noted by the inventive process, where the pulp slurry is
treated first
with the PEO, followed by the addition of the HercobondTM 6950.
Table 1
PEO eHercobond 6950
Run
Number #/T #/T ! 200 mls 250 mls
1 .00 j 720
2 a 2 0 29 52
3 .2 0.5 .. 13 19
. , . . .
4 0.2 0.25 i 14 22
! 0.1 0
= 1 150 360
6 0.1 0.5 io13
7 i 0 0.5 780 . nia
8 0.2 0.5 23 45
