Note: Descriptions are shown in the official language in which they were submitted.
CA 02569823 2006-12-07
WO 2006/003122 PCT/EP2005/052964
Amphoteric Polymers for Controlling Deposition of Pitches and Stickies in
Papermaking
This application claims the benefit of U.S. Provisional Application No.
60/585,184, filed on
July 2, 2004 and U. S. Provisional Application No. 60/662,755, filed March 17,
2005 which
applications are herein incorporated by reference.
The present invention relates to a method for controlling pitch and stickies
deposition in a
pulp and papermaking process using amphoteric copolymers formed from the
monomers
diallyldimethylammonium chloride (DADMAC), acrylic acid and optionally
acrylamide. The
method may optionally further comprise the addition of a siliceous material.
The pitch and
stickies are found in mechanical pulps, recycled fiber, coated broke, white
water and the like.
The invention also encompasses a composition for pitch and stickies control in
papermaking
comprising the amphoteric copolymer and optionally, a siliceous material.
The present invention is directed to the use of compositions comprising
amphoteric polymers
of dial lyid imethylammon iu m chloride (DADMAC) with acrylic acid and
optionally acrylamide
for controlling and preventing deposition of pitch and stickies in
papermaking. The
composition may optionally, further comprise a siliceous material.
The siliceous material may be chosen from one or more of the .materials silica
based
particles, silica microgels, colloidal silica, silica sols, silica gels,
polysilicates, cationic silica,
aluminosilicates, polyaluminosilicates, borosilicates, polyborosilicates,
zeolites and swelling
clays. The siliceous material may be in the form of an anionic
microparticulate material.
When the siliceous material is a swelling clay, it may typically be a
bentonite type clay.
Cationic polymers have been used extensively in paper making as flocculants
for improving
retention and drainage and as coagulants or fixatives to control anionic trash
and deposition
of pitch and stickies. Among the most important and extensively used cationic
polymers for
deposit control are the quaternary ammonium polymers of diallyldialkyl
ammonium
compounds (e.g. DADMAC) and copolymers of epichlorohydrin and dimethylamine
known as
polyamines. Homopolymers of DADMAC and polyamines with high cationic charge
density
are good for neutralizing anionic trash but have limited success for
controlling pitch and
stickies deposition. There is still a need for polymer compositions, which
will prevent pitch
and stickies deposition.
CA 02569823 2006-12-07
WO 2006/003122 PCT/EP2005/052964
-2-
Pitch and stickies are interfering substances in the wet end of papermaking
that can affect
both the machine runnability and paper quality. The term "pitch" used here
refers to a
colloidal dispersion of wood-derived hydrophobic particles released from the
fibers during a
pulping process and is also called wood pitch. Wood pitch includes fatty
acids, resin acids,
their insoluble salts, and esters of fatty acids with glycerol, sterols, and
other fats and waxes.
The hydrophobic components of pitch, particularly triglycerides, are
considered one of the
major factors determining whether the presence of such pitch will lead to
deposit problems.
Deposit-forming pitch often contains significantly high amounts of
triglyciderides.
The term "stickies" used herein refers to sticky materials and interfering
substances that arise
from components of recycled fibers, such as adhesives and coatings. Stickies
can come from
coated broke, recycled waste paper for board making and de-inked pulp (DIP).
The stickies
from coated broke is sometimes called white pitch. Deposition of pitch and
stickies often
leads to defects in the finished product and paper machine downtime causing
lost profits for
the mill. These problems become more significant when paper mills "close up"
their process
water systems for conservation and environmental reasons. Unless the pitch and
stickies are
continuously removed from the system in a controlled manner, these interfering
substances
will accumulate and eventually lead to deposition and runnability problems.
Technology in
place today is based on fixing the pitch or stickies to the fibers before they
have a chance to
agglomerate, or alternatively coating the pitch or stickies with a polymer
that makes them
non-tacky and therefore unable to agglomerate.
Three chemical methods are commonly used by paper mills to control pitch and
stickies
deposit:
1) detackification
2) stabilization
3) fixation
These methods are, however, not commonly used together since they may conflict
with each
otherAn detackification, a chemical is used to build a boundary layer of water
around the
pitch and stickies to decrease depositability. Detackification can be achieved
by addition of
pitch adsorbents such as talc and bentonite. However, pitch adsorbents such as
talc can end
up contributing to the pitch deposit problem if the talc/pitch particles are
unable to be retained
in the paper sheet with surfactants and water-soluble polymers. In
stabilization, surfactants
CA 02569823 2006-12-07
WO 2006/003122 PCT/EP2005/052964
-3-
and dispersants are used to chemically enhance colloidal stability and allow
pitch and
stickies to pass through the process without agglomerating or depositing.
In fixation, polymers are used to fix pitch and stickies to the fiber and
remove them from the
white water system. The interfering substances in papermaking systems are
usually anionic
in nature and are sometimes referred to as anionic trash or cationic demand.
Anionic trash
consists of colloidal (pitch and stickies) and dissolved materials that
adversely affect the
paper making in a variety of ways through deposit formation or interference
with chemical
additives. Removal of anionic trash by reducing cationic demand with a
cationic polymer is a
way of deposit control through fixation. The advantage of using cationic
polymeric coagulants
for pitch and stickies control is that the pitch and stickies are removed from
the system in the
form of microscopic particles dispersed among the fibers in the finished paper
product.
Cationic polymers are normally used as fixatives to control pitch and stickies
through fixation.
Nonionic polymers discussed in PCT Application No. 200188264 such as polyvinyl
alcohol
and copolymers such as polyacrylamide-vinyl acetate have been developed and
used for
stickies control through detackification. U.S. Pat. No. 6,051,160 discloses
hydrophobically
modified anionic polymers such as a copolymer of styrene and maleic anhydride
for used in
pitch deposit control through, most likely, the pitch stabilization mechanism.
Homopolymers of DADMAC are commonly used alone or with other components as
fixatives
for anionic trash control and pitch control.
Canadian Patent No. 1,194,254 teaches a method of reducing wood pitch
particles in
aqueous pulp with a polyDADMAC. The patent does not teach use of the
polyDADMAC for
stickies containing pulps from recycled secondary fibers. Papermakers today
face the
increased use of recycled secondary fiber. Unlike virgin fiber that was used
in the past,
recycled fibers contain stickies from many sources such as glue, adhesives and
coating
binders. The Canadian patent is also limited to use of DADMAC homopolymer.
U.S. Pat. No. 5,989,392 teaches use of crosslinked DADMAC polymers for
controlling
anionic trash and pitch deposition in pulp containing broke. A pulp filtrate
turbidity test is used
to evaluate polymer performance in pitch deposition control therein. Improved
efficiencies of
solution crosslinked or branched polyDADMACs over conventional linear
polyDADMAC are
CA 02569823 2006-12-07
WO 2006/003122 PCT/EP2005/052964
-4-
demonstrated. The crosslinked or branched polyDADMACs used are prepared using
a
polyolefinic crosslinking monomer such as triallylamine hydrochloride or
methylene
bisacrylamide.
U.S. Pat. No. 4,964,955 discloses a method of using an aqueous slurry of
polyDADMAC and
kaolin clay for reducing pitch in pulping and papermaking.
U.S. Pat. No. 4,913,775 provides a process wherein a water soluble
substantially linear
cationic polymer is applied to the paper making stock prior to a shear stage
and then
reflocculating by introducinting bentonite after that shear stage. This
process provides
enhanced drainage and also good formation and retention. This process which is
commercialized by Ciba Specialty Chemicals under the HYDROCOL trade mark has
proved
successful for more than a decade. This process however, relates to retention
and drainage,
not pitch and sticky deposit control. The bentonite and cationic polymer are
normally added
to the thin stock in the papermaking process.
U.S. Pat. No. 4,795,531 describes a method of making paper in which a low
molecular
weight cationic organic polymer is added to the furnish and then a colloidal
silica and a high
molecular weight charged acrylamide copolymer of molecular weight of at least
500,000.
U.S. Pat. No. 5,256,252 discloses a method for controlling pitch deposit using
enzyme
(lipase) with DADMAC polymers. This patent is related more to use of enzyme
which is a
necessary component for the method. A filtrate turbidity test is used to
evaluate pitch control
performance.
U.S. Pat. No. 5,230,774 is directed to a process for controlling pitch
deposits by adding a
blend of a homopolymer of DADMAC and ammonium zirconium carbonate. None of the
polymers are copolymers of DADMAC.
U.S. Pat. No. 5,131,982 teaches use of DADMAC homopolymers and copolymers for
coated
broke treatment to control white pitch. The patent teaches a method of adding
DADMAC
polymer to re-pulped coated broke and then admixing the treated coated broke
pulp with
other fiber sources before forming a paper sheet. Use of DADMAC polymers for
pitch and
stickies control for mechanical pulp and deinked recycled pulp is not taught.
The copolymers
CA 02569823 2006-12-07
WO 2006/003122 PCT/EP2005/052964
-5-
claimed are mainly copolymers of DADMAC and acrylamide with more than 25% of
acrylamide.
European Application No. 464,993 discloses use of an amphoteric copolymer of
DADMAC
and acrylic acid salts for controlling wood pitch deposition or natural pitch.
A filtrate turbidity
test is one of the test methods used to evaluate pitch deposit control
performance. The
polymers disclosed are not claimed for use in deposit control of stickies and
white pitch in
recycle pulps and coated broke.
PCT Application No. 200034581 teaches use of amphoteric terpolymers of DADMAC,
acrylamide and acrylic acid as a retention/drainage/formation aid in a
papermaking process.
The terpolymers are also taught for controlling white pitch for coated broke.
Terpolymers of
DADMAC, acrylamide and acrylic acid are disclosed for treating white pitch
wherein the
termpolymer contains more than 25% of acrylamide and not more than 50% of
DADMAC. A
filtrate turbidity test is used to determine the polymers white pitch deposit
control
performance.
European Application No. 058622 teaches a method for reducing or preventing
the
deposition of wood pitch during the papermaking process with an emulsion
copolymer of
DADMAC, DADEAC, acrylamide and acrylic acid. The copolymer contains 45 to 50%
acrylamide, no more than 50 wt% of DADMAC and at least 2 wt% of an uncommon
monomer, DADEAC, (diallyidiethylammonium chloride) which is not commercially
available
today. No mention is made for use of the copolymer for stickies control of
recycled fibers.
U.S. Pat. No. 4,505,828 teaches use of an inverse emulsion amphoteric
copolymer made
from acrylamide, acrylic acid and dimethylaminoethyl methacrylate in petroleum
recovery by
a water flooding process and in papermaking as a drainage aid. Use of a
solution amphoteric
terpolymer of DADMAC, acrylamide and acrylic acid is not taught. The patent is
not related to
pitch and stickies deposit control in papermaking.
U.S. Pat. No. 3,639,208 discloses the preparation and composition of certain
amphoteric
terpolymers of DADMAC, acrylamide and acrylic acid obtained by partly
hydrolyzing a
copolymer of acrylamide and DADMAC. The copolymer and its hydrolyzed
terpolymer
CA 02569823 2006-12-07
WO 2006/003122 PCT/EP2005/052964
-6-
contains less than 70% DADMAC. The terpolymers obtained are used as retention
aids in
papermaking. Use of the amphoteric terpolymer for pitch control is not taught.
US Pat. No. 5,837,100 teaches the use of blends of a dispersion polymer and a
coagulant for
coated broke treatment to improve retention and/or drainage. The water
dispersion polymer
is a copolymer of acrylamide and quaternary dimethylaminoethyl acrylate. The
coagulant is a
copolymer of epichlorohydrin and dimthylamine. Turbidity reduction testing is
used to
determine the activity efficiency of the polymers.
Fixatives with increased pitch and stickies fixation power are needed. Alum,
starches and low
molecular weight cationic coagulants conventionally used for deposit control
can neutralize
anionic trash and detrimental substances (pitch and stickies) and form
complexes. However,
they may not carry sufficient charge and/or molecular weight to fix pitch and
stickies
complexes to the fiber. If not strongly fixed to the fibers, the complexes
will become
concentrated in the system and will lead to deposition problems.
Innovations in fixatives for runnability improvement by the present inventors
have led to
development of a number of diallyidimethylammonium chloride (DADMAC)
copolymers with
high fixation power for pitch and stickies control. These DADMAC polymers have
significantly
greater power to remove detrimental pitch and stickies from a papermaking
water system
than existing commercial fixative products. When combined with siliceous
material, the
polymers are also effective.
The above review shows that there is a need for controlling pitch and stickies
deposition in
paper making with effective polymers. The search for polymer compositions,
which will
prevent pitch and stickies deposition has met with limited success and is
still ongoing. It has
now been found that an amphoteric DADMAC copolymer with high DADMAC and
acrylic acid
(AA) units wherein the acrylic acid units are in an amount from about 0.2 to
about 30%
based on the weight of the DADMAC copolymer content is very effective in
reducing pitch
and stickies. The amphoteric polymers are effective when used on their own and
when
combined with siliceous material.
A dual functional polymer capable of controlling deposition through both
fixation and anionic
trash reduction is desirable. The inventive water-soluble amphoteric polymers
described
CA 02569823 2006-12-07
WO 2006/003122 PCT/EP2005/052964
-7-
herein serve this dual purpose since they contain anionic and nonionic
hydrogen bonding
groups in addition to cationic functionality for fixation and charge
neutralization. The
polymers are also effective when combined with siliceous material.
Amphoteric polymers are polyelectrolytes containing both positive and negative
charges in
the same polymer molecule. Amphoteric DADMAC polymers are DADMAC polymers,
which
also contain negative charges in the formed polymer.
One objective of this invention is to provide for pitch and stickies deposit
control in
papermaking with an amphoteric polymer of DADMAC containing anionic groups,
which
impart variable charge density and hydrophobicity for the polymer in response
to pH change.
Another objective of this invention is to provide for pitch and stickies
deposit control in
papermaking an amphoteric polymer of DADMAC further containing nonionic
functional
groups, which can provide additional interactions through hydrogen bonding in
addition to
ionic charge interaction.
Accordingly, the invention encompasses a process for pitch and stickies
deposit control in
papermaking comprising adding to a paper furnish a composition comprising an
amphoteric
polymer
R
P n m
O + O
H2N ~/N~R1 M+
X
wherein X is an anion;
M is hydrogen, ammonium, sodium, or potassium;
R is hydrogen or methyl;
R1 is methyl or ethyl;
n is from about 70 to about 99.8 wt.%,
m is from about 0.2 to about 30 wt.%, and
CA 02569823 2006-12-07
WO 2006/003122 PCT/EP2005/052964
-8-
p is from about 0 to about 30 wt.%,
wherein n + m + p = 100% based on the total weight of the amphoteric polymer.
Preferably X is Cl,
M is sodium,
n is from about 85 to about 98 wt.%,
m is from about 1 to about 15 wt.%, and
p is from about 1 to about 10 wt.% by weight based on the total weight of the
amphoteric
polymer.
The amphoteric polymer composition may further comprise at least one siliceous
material.
The amphoteric polymer may be added before, after or simultaneously with the
siliceous
material to the furnish. For example, the amphoteric polymer may be added to
the furnish
before the siliceous material is added separately to the furnish.
The ratio of cationic charge to anionic charge refers to the ratio of the
moles of the cationic
monomer or cationic monomers divided by the moles of the anionic monomer or
anionic
monomers which form the amphoteric polymer.
The present inventors have discovered that a cationic amphoteric DADMAC
polymer with a
ratio of cationic charge to anionic charge greater than about 1.2 can be
successfully used to
control pitch and stickies deposit by removing the pitch and stickies from the
system in the
form of microscopic particles.
The present invention is directed to the application of a composition
comprising water-soluble
amphoteric polymer for controlling and preventing deposition of pitch and
stickies in
papermaking. The method comprises the step of adding the composition to treat
mechanical
pulp for controlling wood pitch deposits, coated broke for controlling
stickies or with pitch
deposit, and recycled pulp for controlling stickies deposit. The composition
comprising an
amphoteric polymer may further comprise a siliceous material The siliceous
material may be
added after, before or simultaneously with the amphoteric polymer. The
siliceous material
may be added separately after or before the amphoteric polymer.
CA 02569823 2006-12-07
WO 2006/003122 PCT/EP2005/052964
-9-
The cationic amphoteric polymer is made by radical polymerization of for
example, DADMAC
with (meth)acrylic acid and/or acrylamide.
in the invention, the amphoteric polymer is any polymer containing both
cationic charges and
anionic charges. The amphoteric polymer is an amphoteric polymer with a total
cationic
charge content greater than the total anionic charge. The amphoteric polymer
can be a
polymer formed from two monomers derived from cationic and anionic monomers or
a
terpolymer of three monomers derived from cationic, anionic and nonionic
monomers.
Cationic polymers are commonly used in papermaking to remove anionic trash by
charge
neutralization. Anionic trash consists of colloidal (pitch and stickies) and
dissolved materials
that adversely affect the papermaking in a variety of ways through deposit
formation or
interference with chemical additives. Removal of anionic trash by fixing the
colloidal particles
to fiber and reducing the cationic demand with a cationic polymer is a way of
pitch and
stickies deposit control. The advantage of using cationic polymeric coagulants
for pitch and
stickies control is that the pitch and stickies are removed from the system in
the form of
microscopic particles dispersed among the fibers in the finished paper
product.
The present inventors have discovered that the fixation of pitch and stickies
to paper fiber
and charge neutralization can be enhanced by the use of amphoteric copolymers
with a mole
ratio of cationic charge to anionic charge greater than about 1.2, preferably
greater than
about 4 and most preferably greater than about 5. The amphoteric copolymers
are formed by
polymerization of diallyldialkylammonium compounds and (meth)acrylic acid
(and/or its salts)
and optionally acrylamide. For example, the diallyidialkyl ammonium compounds
are
diallyidimethylammonium chloride (DADMAC).
The amphoteric polymer of the present invention can be represented by the
following
structure:
CA 02569823 2006-12-07
WO 2006/003122 PCT/EP2005/052964
-10-
* R
p n
m
0 + 0 (i)
H~N ~1~R M+
1
x
wherein X is an anion;
M is hydrogen, ammonium, sodium, or potassium;
R is hydrogen or methyl;
R1 is methyl or ethyl;
n is from about 70 to about 99.8 wt.%;
m is from about 0.2 to about 30 wt.%
and
p is from about 0 to about 30 wt. % with n + m + p 100% based on the total
weight of the
amphoteric polymer.
Preferably X is CI;
M is sodium;
n is from about 85 to about 98 wt.%;
m is from about 1 to about 15 wt.%
and
p is from about 1 to about 10 wt.% based on the total weight of the amphoteric
polymer.
The unit n of the above polymer represents a unit derived from a cationic
monomer chosen
from diallyldialkylammonium compounds.
For example, the cationic monomer can be a diallyidiethylammonium halide or
diallydimethylammonomium halide.
The unit m of the above polymer represents a unit derived from at least one
anionic
monomer chosen from hydrolysed acrylamide and (meth)acrylic acids and /or
salts thereof.
CA 02569823 2006-12-07
WO 2006/003122 PCT/EP2005/052964
-11-
The amphoteric DADMAC polymer for use in accordance with the present invention
may be
one containing cationic charge in excess of the anionic charge. The molar
ratio of n/m may
be for example, greater than about 1.2; greater than about 4 or greater than
about 5.
The amphoteric DADMAC polymer may have a weight average molecular weight
ranging
from about 10,000 to about 20,000,000, from about 100,000 to about 2,000,000
or from
about 300,000 to about 2,000,000.
The amphoteric DADMAC polymer can be used in dosages that range from about
0.01 to
about 20 lbs/ton, or from about 0.2 to about 10 lbs/ton based on dry solids.
Polymerization of the amphoteric polymer can be carried out by aqueous
solution
polymerization, water-in-oil inverse emulsion polymerization or dispersion
polymerization
using a suitable free radical initiator. Examples of suitable initiators
include persulfates such
as ammonium persulfate (APS); peroxides such as hydrogen peroxide, t-butyl
hydroperoxide, and t-butyl peroxy pivalate; azo initiators such as 2,2'-
azobis2-amidino-
ropane) dihydrochloride, 4,4'-azobis-4-cyanovaleric acid and 2,2'-
azobisisobutyronitrile; and
redox initiator systems such as t-butyl hydroperoxide/Fe(II) and ammonium
persulfate/bisulfite. Aqueous solution polymerization using ammonium
persulfate (APS) is a
preferred method for preparing an amphoteric polymer from for example DADMAC,
(meth)acrylic acid and acrylamide.
(Meth)acrylic acid monomer can be used in its acid form in polymerization. The
produced
acid polymer solution can then be neutralized with a suitable base to the
desired pH and
counter ions. Alternatively, (meth)acrylic acid monomer can be partly or
completely
neutralized before polymerization. Examples of suitable bases for
neutralization of
(meth)acrylic acid monomeric units include NaOH, KOH, and (NH4)OH.
The polymerization may be carried out in the absence of oxygen. Oxygen can be
removed
from the reaction medium by applying vacuum with agitation or by purging with
an inert gas
such as nitrogen or argon. The polymerization can then be conducted under a
blanket of the
inert gas.
CA 02569823 2006-12-07
WO 2006/003122 PCT/EP2005/052964
-12-
The siliceous material may be chosen from one or more of the materials silica
based
particles, silica microgels, colloidal silica, silica sols, silica gels,
polysilicates,
aluminosilicates, polyaluminosilicates, borosilicates, polyborosilicates and
zeolites. This
siliceous material may be in the form of an anionic microparticulate material.
Alternatively the
siliceous material may be cationic silica.
In one more embodiment of the invention, the siliceous material may be
selected from silicas
and polysilicates. The silica may be any colloidal silica, for instance as
described in
U.S. Pat. No. 4,961,825. The polysilicate may be a colloidal silicic acid as
described in
U.S. Pat. No. 4,388,150.
The polysilicates of the invention may be prepared by acidifying an aqueous
solution of an
alkali metal silicate. For instance, polysilicic microgels otherwise known as
active silica may
be prepared by partial acidification of alkali metal silicate to pH of about 8
to about 9 by use
of mineral acids or acid exchange resins, acid salts and acid gases. It may be
desirable to
age the freshly formed polysilicic acid in order to allow sufficient three
dimensional network
structure to form. Generally the time of ageing is insufficient for the
polysilicic acid to gel.
Particularly preferred siliceous materials include polyalumino-silicates. The
polyalumino-
silicates may be for instance aluminated polysilicic acid, made by first
forming polysilicic acid
microparticies and then post treating with aluminium salts, for instance as
described in
U.S. Pat. No. 5,176,891. Such polyaluminosilicates consist of silicic
microparticles with the
aluminium located preferentially at the surface.
Alternatively the polyaluminosilicates may be polyparticulate microgels of
surface area in
excess of 1000 m2 /g formed by reacting an alkali metal silicate with acid and
water soluble
aluminium salts, for instance as described in U.S. Pat. No. 5,482,693.
Typically the
polyaluminosilicates may have a mole ratio of alumina:silica from between
about 1 to about
10 to about 1 to about 1500 (- 1:-10 to - 10:- 1500).
Polyaluminosilicates may be formed by acidifying an aqueous solution of alkali
metal silicate
to about pH 9 or about 10 using concentrated sulphuric acid containing about
1.5 to about
2.0% by weight of a water soluble aluminium salt, for instance aluminium
sulphate. The
aqueous solution may be aged sufficiently for the three dimensional microgel
to form.
CA 02569823 2006-12-07
WO 2006/003122 PCT/EP2005/052964
-13-
Typically the polyaluminosilicate is aged for up to about two and a half hours
before diluting
the aqueous polysilicate to about 0.5 weight % of silica.
The siliceous material may be a colloidal borosilicate, for instance as
described in
WO-A-9916708. The colloidal borosilicate may be prepared by contacting a
dilute aqueous
solution of an alkali metal silicate with a cation exchange resin to produce a
silicic acid and
then 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 about
0.01 to about
30% B203, having a pH from about 7 to about 10.5.
When the siliceous material is a silica or silicate type material it has a
particle size in excess
of 10 nm. The silica or silicate material for example, has a particle size in
the range of about
to about 250 nm, or in the range about 40 to about 100 nm.
15 The siliceous material may be a swelling clay. The swellable clays may for
instance be
typically a bentonite type clay. The preferred clays are swellable in water
and include clays
which are naturally water swellable or clays which can be modified, for
instance by ion
exchange to render them water swellable. Suitable water swellable clays
include but are not
limited to clays often referred to as hectorite, smectites, montmorillonites,
nontronites,
20 saponite, sauconite, hormites, attapulgites and sepiolites. These clays may
be either
naturally occurring or synthetic. An example of a synthetic hectorite clay
would be
LAPONITE available from Southern Clay Products, Inc., U.S.A. Typical anionic
swelling clays
are described in U.S. Pat. Nos. 4,753,710 and 4,913,775.
The clay may be a bentonite type clay. The bentonite may be provided as an
alkali metal
bentonite. Bentonites may be natural or synthetic. Naturally occurring
bentonites may be
either as alkaline bentonites, such as sodium bentonite or as the alkaline
earth metal salt,
usually the calcium or magnesium salt. Generally the alkaline earth metal
bentonites are
activated by treatment with sodium carbonate or sodium bicarbonate. Activated
swellable
bentonite clay is often supplied to the paper mill as dry powder.
Alternatively the bentonite
may be provided as a high solids flowable slurry of activated bentonite, for
example at least
about 15 or about 20% solids, for instance as described in U.S. Pat. Nos.
5,223,098,
6,024,790 and 6,045,657.
CA 02569823 2006-12-07
WO 2006/003122 PCT/EP2005/052964
-14-
The bentonite may be applied to the cellulosic suspension as an aqueous
bentonite slurry.
When supplied to the paper mill as a high solids flowable slurry usually the
slurry is diluted to
an appropriate concentration. Typically the bentonite slurry comprises up to
10 wt. %
bentonite. The bentonite slurry will normally comprise at least about 3 wt. %
bentonite clay,
typically about 5 wt. % bentonite. The bentonite may be added to the
cellulosic suspension
either before or after addition of the amphoteric polymer. The bentonite may
also be added
simultaneously, but separately with the amphoteric polymer.
Desirably the siliceous material is applied in an amount of at least about 100
ppm by weight
based on dry weight of suspension. Desirably the dose of siliceous material
may be as much
as about 10,000 ppm by weight or higher. In one preferred aspect of the
invention doses of
about 100 to about 500 ppm by weight have been found to be effective.
Alternatively, higher
doses of siliceous material may be desired, for instance about 1000 to about
2000 ppm by
weight.
Dosages in the paper industry are frequently expressed in the units kg/ton
based on dry
weight of the furnish. Expressed in these units the amount of siliceous
material added to the
furnish may range from about 0.2 to about 10 kg/ton; about 1.0 to about 6
kg/ton; or about
1.0 to about 4 kg/ton based on the dry weight of the furnish.
The weight to weight ratio of the amphoteric polymer to siliceous material may
range from
about 0.2 to about 10; from about 1 to about I to from about 1 to about 4; or
about I to about
2. For example, the fixative or polymer may range from about 0.5 to about 2
kg/ton with the
siliceous dosage ranging from about 1 to about 2 kg/ton.
For deposit control the siliceous material and the polymeric fixative are
preferably added to
the thick stock (about 2-4% cellulose concentration) during the papermaking
process.
The amount of the free radical initiator used in the polymerization process
depends on the
total monomer concentration and the type of monomers used and may range from
about
0.2 to about 5.0 wt % of the total monomer charge to achieve conversion of
more than about
99 wt. % of the total monomer.
CA 02569823 2006-12-07
WO 2006/003122 PCT/EP2005/052964
- 15-
The specific embodiments of this invention are illustrated by the following
examples. These
examples are illustrative of this invention and not intended to be limiting.
Examples
Synthesis of Polymers
Example 1
Synthesis of Amphoteric DADMAC Polymers 1- 10 and DADMAC homopolymer Control
The procedure for making Polymer 1 is described in this example. Other
polymers are made
following the same procedure, but using different monomer weight ratios,
initiator feeds and
temperature to obtain polymers with different compositions and molecular
weights. Molecular
weights of the polymers are measured using the bulk viscosity or Brookfield
viscosity (BV) at
20% polymer solids. A high 20% BV value indicates a high MW. Properties of the
polymers
synthesized are shown in Table 1.
A 1-liter reactor equipped with a condenser, a thermometer, a nitrogen inlet,
and an
overhead agitator is charged with 453.86 g of 66% monomer DADMAC, 15.8 g of
acrylic
acid, 59 g of deionized water and 0.15 g of Versene (Na4EDTA). 35 g of a 25%
NaOH
solution is added slowly to the reactor at room temperature to neutralize the
acrylic acid. The
polymerization mixture is purged with nitrogen and heated with agitation to a
temperature of
about 90 C. 36 g of a 14.5% ammonium persulfate (APS) aqueous solution was
slowly fed
to the reactor over 165 minutes. The reaction temperature is allowed to
increase to above
100 C and then maintained at 100 to 110 C during the APS feed period. After
the APS feed,
the reaction mixture is diluted with deionized water to about 40% solids and
held at 90 C for
about 30 minutes. Then an aqueous solution containing 5.6 g of sodium
metabisufite is
added over 40 minutes. The reactor is held at 90 C for another 30 minutes to
complete the
polymerization (above 99% conversion). The polymer solution is diluted with
sufficient water
to about 35% solids. This product has a solids content of 35.3 wt. % with a 25
C Brookfield
viscosity of 8,800 cps and a 25 C Brookfield viscosity at 20% solids (20% BV)
of about
400 cps. The 20% BV is proportional to molecular weight of the polymer and
therefore the
data are used to compare the molecular weights of different solution polymers.
Unless,
CA 02569823 2006-12-07
WO 2006/003122 PCT/EP2005/052964
-16-
stated to the contrary all percents are based on total weight. All monomer
ratios are based
on total weight of the monomers.
Table 1
Copolymers of DADMAC, acrylic acid and acrylamide
Sample M1/M2/M3 Solids 2Viscosity, 20% BV at
cps 25 C, cps
Control 100/0/0 34.6% 7,850 10
Polymer 1 5/5/0 35.3% 3,800 100
Polymer 2 0/10/0 5.3% 3,850 00
Polymer 3 5/5/0 5.4% 15,700 30
Polymer 4 0/10/0 5.4% 15,560 25
Polymer 5 30/20/0 4.6% 39,800 1500
Polymer 6 30/40/0 4.6% 31,000 1300
Polymer 7 5/5/0 1.1 % 2760 180
Polymer 8 2/80 1.5% 2730 1960
Polymer 9 2.5/2.515 1.6% 2860 1990
Polymer 10 1/8/1 20.3% 2400 2240
1. Homopolymer of DADMAC
2. Viscosities of 1000 to 3000 cps, use spindle LV3 at 30rpm; 3000 to 8000 cps
use spindle LV3 at 12 rpm and 8,000 to 16,000 cp, use spindle LV3 at 6 rpm.
*M1 = DADMAC; M2 = acrylic acid (AA); M3 = acrylamide
Performance Evaluation
Commercial products listed in Table 2 are also used for comparision in the
evaluation.
Table 2A
Existing commercial fixatives (EFC) products tested
Product ID Polymer Chemistry
Alcofix 269 Low MW DADMAC homopolymer
Alcofix 110 High MW DADMAC homopolymer
Alcofix 111 High MW DADMAC homopolymer
Alcofix 159 Medium MW polyamine
Alcofix 160 High MW polyamine
CA 02569823 2006-12-07
WO 2006/003122 PCT/EP2005/052964
-17-
Alcofix 158 Low MW polyamine
1Alcofix 161 DADMAC copolymer
Alcofix 505 DADMAC copolymer
Raifix 120 Cationic starch
1. Copolymer of 95 wt. % DADMAC and 5 wt. % acrylamide
2. Copolymer of 50 wt.% DADMAC and 50 wt.% acrylamide.
A vacuum drainage filtrate turbidity test is used to demonstrate the
performance of the
amphoteric polymers of the present invention and commercial fixatives products
and their
ability to fix pitch, stickies and other contaminants onto fibre and therefore
control and
prevent these contaminants from deposition during paper making. The detailed
test
procedure is shown below.
1. About 250 mL of a 3 - 5% consistency furnish is measured into a baffled
Britt jar.
Adequate mixing is provided with a IKA mixer set to agitate at 1000 rpm.
2a. The required amount of polymer is added to the agitated thick stock and
allowed to mix
for 2 minutes.
2b. Optionally, the required amount of siliceous material is added to the
agitated thick stock
and allowed to mix for 2 minutes.
3. The treated thick stock.. is then filtered through a Whatman 541 filter
paper (11 cm
diameter, coarse - retention for particles > 20-25 microns) under vacuum.
4. Vacuum filtration continues until the "wet line" just disappears or
approximately 200 mLs of
filtrate is collected.
5.Turbidity of the filtrate is measured with a suitable turbidimeter.
6. Cationic charge demand (CCD) of the filtrate is determined by colloidal
titration.
Dosage used is in weight of active polymer per ton of pulp solids (dry
weight).
The lower the filtrate turbidity, the greater is the pitch and stickies
control of the treatment
employed and therefore the better performance of the polymer used.
CA 02569823 2006-12-07
WO 2006/003122 PCT/EP2005/052964
-18-
Example 2
The samples tested in this example all have a relatively low molecular weight
expressed by
the 20% BV of about 400 cps. Testing is performed on 100 % recycled old
corrugated
container (OCC) furnish from a linerboard mill experiencing serious stickies
deposit problem.
This example shows that with similar MW, the amphoteric DADMAC copolymer
Polymer I
performs better in the turbidity reduction than the DADMAC homopolymer
control. Results in
Table 2B for the Control, Polymer 1 and Polymer 2, demonstrate that the
performance
improvement with incorporation of the AA anionic component is diminished when
the AA
content is above 10%.
Table 2B
100 % recycled Old Corrugated Containe
(OCC) furnish blank Turbidity, 379 NTU
(a) Dosage, kg/ton 1.0 2.0 .0
(ii) Turbidity, NTU
Control 1(homopolymer 0% AA) 57 49 13
Polymer 1 (5% AA) 57 J46 39
Polymer 2 (10% AA) 60 j54 12
Example 3
The samples tested in this example all have a higher molecular weight
expressed by the
20% BV of above 600 cps. Testing is performed on 100 % recycle deinked pulp
furnish from
a paper mill. This example further demonstrates that the performance
improvement with
incorporation of AA anionic component is diminished when the AA content is
above 10%.
See Table 3A. A commercial fixative (Alcofix 159, a medium MW polyamine)
commonly used
for deposit control in paper mills is also included in the testing. Polymer 3
of the present
invention gives significantly better performance in turbidity reduction than
the commercial
fixatives.
CA 02569823 2006-12-07
WO 2006/003122 PCT/EP2005/052964
-19-
Table 3A
100% recycled furnish deinked pulp (DIP)
urnish blank turbidity, 578 NTU
(a) Dosage, kg/ton 0.2 0.4 0.8
(iii) Turbidity, NTU
Commercial fixative (Alcofix 159) 126 73 50
Polymer 3 (5% AA) 99 63 1
Polymer 4(10% AA) 176 104 9
Polymer 5 (20% AA) 149 105 51
Polymer 6 (40% AA) 159 101 50
Example 4
Performance on coated broke
Performance of the DADMAC copolymers of the present invention for white pitch
control is
evaluated on different types of coated broke. The samples are tested on the
following three
types of broke.
= 45# Pub Matte, a light-weight free sheet
= 38# DPO, heavy weight groundwood containing
= 70# DPO, heavy weight groundwood containing
For each dosage of polymer treatment, the turbidity and cationic demand of the
filtrate is
measured. The results of the study are shown in the Tables 4A, 4B and 4C.
Table 4A
45# Pub Matte: Turbidity of treated furnish at different dosage (lb/ton on dry
solids basis)
Dosage (lb/ton) 0.4 0.8 1.2 1.6 2.4
Polymer 7 2635 511 176 110
Polymer 8 2792 396 194 120
Polymer 9 2558 414 166 68
Alcofix 110 2995 825 246 200
Alcofix 269 2011 322 248
Alcofix 159 1258 447 316
CA 02569823 2006-12-07
WO 2006/003122 PCT/EP2005/052964
-20-
Table 4B
70# DPO: Turbidity of treated furnish at different dosage (lb/ton on dry
solids basis)
Dosage (lb/ton) 0.4 0.8 1.2 1.6 2.4
Polymer 7 110 57 44 31
Polymer 8 141 49 29 35
Polymer 9 88 56 31 31
Alcofix 110 170 87 58 46
Alcofix 269 157 130 97
Alcofix 159 110 87 72
Table 4C
38# DPO: Turbidity of treated furnish at different dosage (lb/ton on dry
solids basis)
Dosage(lb/ton) 0.4 0.8 1.2 1.6 2.4
Polymer 7 10372 4090 2246 302
Polymer 8 4894 605 131 56
Polymer 9 7556 2596 329 122
Alcofix 110 11368 5192 2172 184
Alcofix 269 2512 247 127
Alcofix 159 6856 2286 319
The test data on existing commercial fixative products (Alcofix 269, Alcofix
110, and Alcofix
159) are also obtained for comparison and show the benefit of using the
copolymers of the
present invention. The copolymers of the present invention give performance
significantly
better than all the commercial products tested.
Example 5
Performance on deinked pulp (DIP) recycled furnish.
The test data on recycled deinked pulp (DIP) are obtained to show performance
of the
amphoteric DADMAC copolymers over existing commercial fixatives products
Alcofix 161, a
coplymer of DADMAC and acrylamide. The new DADMAC-based amphoteric polymer
CA 02569823 2006-12-07
WO 2006/003122 PCT/EP2005/052964
-21 -
samples give performance significantly better than the commercial products.
Improvements
of up to about 50% over a commercial DADMAC copolymer (Alcofix 161) in average
turbidity
reduction are obtained.
Filtrate turbidity (FT) results in Table 5 show DIP furnish treatment with
amphoteric DADMAC
copolymers and compare with furnish treated with a commercial DADMAC copolymer
(Alcofix 161).
Lower FT indicates better performance for stickies deposit control.
Table 5
Dosage(lb/ton) 1.0 2.0 3.0 4.0 Average FT, % FT
NTU reduction
over
Alcofix161
Alcofix 161 131 87 65 49 83 0
Polymer 1 111 64 52 45 68 18.1
Polymer 3 100 55 45 41 60 27.4
Polymer 7 98 48 48 34 57 31.3
Polymer 8 71 41 29 23 41 50.6
Example 6
Performance on TMP, DIP and TMP/DIP mix furnish.
Amphoteric DADMAC copolymers of the present invention are evaluated on three
types of
furnish (TMP, DIP and mix of DIP&TMP) from a paper mill together with nine
commercial
products. Various commercial fixative products included in the testing are 3
DADMAC
homopolymers with different molecular weights, 2 copolymers of DADMAC and
acrylamide
with different monomer ratios and molecular weights, 3 polyepiamines with
different
molecular weights and structures, and 1 cationic starch. Of the 9 commercial
fixatives tested,
Alcofix 161, a DADMAC copolymer, performed consistently the best among the
commercial
products. Therefore, results of the amphoteric DADMAC copolymers of the
present invention
are compared only to those of Alcofix 161 to show their performance over
existing
commercial fixative products. As can be seen from Table 6A, B and C, the
amphoteric
* DADMAC copolymers of the present invention perform significantly better than
the best
CA 02569823 2006-12-07
WO 2006/003122 PCT/EP2005/052964
-22-
commercial fixative for all three types of furnishes. An improvement of
greater than about
20 to about 74% turbidity removal over Alcofix 161 is observed using the
amphoteric
DADMAC copolymers of the present invention.
Table 6A
Filtrate turbidity (FT) of treated furnish with 100% TMP at different dosages
(kg/ton on dry
solids base). Turbidity of untreated furnish is 213 NTU.
Dosage (kg/ton) 0.25 0.5 1.0 2.0 Average % FT reduction
FT, NTU over Alcofix161
Alcofix 161 154 120 80 43 99 0
Polymer 7 126 96 63 27 78 20
Polymer 8 116 95 57 23 73 24
Polymer 9 131 91 71 23 58 19
Table 6B. Filtrate turbidity (FT) of treated furnish with 100% DIP at
different dosage (kg/ton
on dry solids base). Turbidity of untreated furnish is 218 NTU.
Dosage (kg/ton) 0.10 0.2 Average % FT reduction
FT, NTU over Alcofix161
Alcofix 161 100 41 71 0
Polymer 7 78 28 53 25
Polymer 8 62 25 44 38
Polymer 9 79 32 56 21
Table 6C. Filtrate turbidity (FT) of treated furnish with 60% TMP and 40% DIP
at different
dosages (kg/ton on dry solids base). Turbidity of untreated furnish is164 NTU.
Dosage (kg/ton) 0.10 0.2 Average % FT reduction
FT, NTU over Alcofix161
Alcofix 161 125 103 114 0
Polymer 7 106 77 92 45
Polymer 8 90 64 77 74
Polymer 9 115 85 100 28
CA 02569823 2006-12-07
WO 2006/003122 PCT/EP2005/052964
-23-
Example 7
Filtrate turbidity (FT) of treated furnish of 100% TMP at different dosages
(kg/ton on dry
solids basis) of fixative and bentonite.
The turbidity and total ester concentrations (a measure of pitch) are
determined in the filtrate
and compared in Table 7. The testing procedure is essentially the same as that
preformed
for the commercial fixatives shown in Table 2 except a 2% consistency furnish
is tested and
the residual ester, triglyceride esters and total ester pitch concentrations
are determined
using gas chromatography (GC).
The GC analysis was run on a DB-5HT 5m x 0.25 mm X 0.10 micron column, an
Inlet
temperature of 300 C and an FID Detector temperature of 350 C. The heating
program:
Initial temp of 100 C hold for 1 minute then increase 15 C/min up to 350 C
and hold for
15 minutes.
Table 7
Filtrate turbidity (FT) of treated furnish of mechanical pulp at different
dosages (kg/ton on dry
solids basis).
Polymer Bentonite Centrifuged Residual Tri- Ester
dosage dosage Turbidity Ester glyceride Pitch
(solids Conc. esters Total
basis)
Treatment Kg/ton kg/ton NTU (ppm) (ppm) (ppm)
Blank 0 0 564 2.4 1.5 3.9
Alcofix 269 1 0 362 0.6 0.6 1.2
1Polymer 10 1.0 0 455 0.6 0.6 1.2
2bentonite 0 2.0 398 1.3 1.2 2.5
bentonite 1.0 2.0 337 0.2 0.2 0.4
followed by
Polymer 10
1. Terpolymer of DADMAC, acrylic acid and acrylamide.
CA 02569823 2006-12-07
WO 2006/003122 PCT/EP2005/052964
-24-
2. Bentonite is supplied under the tradename HYDROCOL 2D1 from Ciba Specialty
Chemical Corp. The HYDROCOL 2D1 was supplied as a 5% aqueous slurry based on
the total weight of the aqueous slurry.
Example 8
Treatment of coated broke with polymer and bentonite
The furnish is primarily bleached TMP. The furnish is combined with about 12
to about 20 %
coated broke and diluted to approximately 3% consistency using white water
from the mill
process. Bentonite was added first as a 5% aqueous slurry at a dosage of 1.5
kg/t then
followed by polymer 10. Table 8 shows the improvement in turbidity when the
amphoteric
polymer is combined with bentonite.
Table 8
Tubidity knockdown for coated broke
Treatment Turbidity in NTU
Blank 925
Alcofix 269 (0.4 kg/ton) 287
Polymer 10 (0.2 kg/ton) 240
Polymer 10 (0.8 kg/ton) + 1bentonite (1.5 130
kg/ton)
1. Bentonite is supplied under the tradename HYDROCOL 2D1 from Ciba Specialty
Chemical Corp.
It should be understood that the above description and examples are
illustrative of the
invention, and are not intended to be limiting. Many variations and
modifications are possible
without departing from the scope of this invention.
