CA 02245507 1998-07-31
\~VO 97128311 PCT/LFS97/01274
El ~LSIFIER SYSTEM FOR ROSIN SIZING AGENTS
Field of the Invention
This invention relates to the emulsification and colloidal stabilization of
rosin sizing agents, and is directed to a stable rosin sizing composition or
dispersion, a
method of making the stable sizing dispersion, a method of using the sizing
composition
to produce sized paper, and sized paper, including paperboard, sized with the
sizing
composition.
$ackground of the Invention
While there are a myriad of details for manufacturing paper, the paper
manufacturing process conventionally comprises the following steps: ( 1 )
forming an
aqueous suspension of cellulosic fibers, commonly known as pulp; (2) adding
various
processing and paper enhancing materials, such as strengthening and/or sizing
materials;
{3) sheeting and drying the fibers to form a desired cellulosic web; and (4)
post-treating
tlae web to provide various desired characteristics to the resulting paper,
including surface
application of sizing materials, and the like.
Sizing materials are typically in the form of aqueous solutions,
dispersions, emulsions or suspensions which render the paper treated with the
sizing
agent, namely sized paper, resistant to the penetration or wetting by an
aqueous liquid,
including other treatment additives, printing inks, and the like.
Sizing agents are internal additives employed during papermaking or
external, surface additives employed at the size press that provide the
enhanced
characteristics. There are two basic categories of sizing agents: acid and
alkaline. Acid
w sizing agents are intended for use in acid papermaking systems,
traditionally less than
about pH 6. Analogously, alkaline sizing agents are intended for use in
alkaline
papermaking systems.
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WO 97/28311 PCT/LTS97/OI274
Most acid sizing agents are based on rosin. The development of sizing
with a rosin-based size is dependent upon its reaction with compounds capable
of
forming an aluminum rosinate, typically papermaker's alum, aluminum sulfate,
Alz{SOa)3,
with various amounts of water of hydration. Other similar equivalent well-
known
aluminum compounds, such as aluminum chloride, aluminum chlorohydrate,
poiyaluminum chlorides, and mixtures thereof, may also be used. Rosin and alum
or its
equivalents complex either in the wet end of the papermaking system or during
elevated
. temperature drying to form aluminum rosinate, which renders the paper
hydrophobic.
Since aluminum species that exist predominantly at a low pH (about <pH 6) are
required
for the appropriate interactions needed to effect sizing, rosin and alum have
been used
primarily in acid papenmaking systems. It has been shown that, by proper
selection of
addition paints in the papermaking system and by using cationic dispersed
rosin sizes,
rosin-based sizes can be used in papermaking systems up to about pH 7, thus
extending
the range of acid sizes. However, due to the limitations imposed by alum
chemistry, the
efficiency of rosin-based sizes decreases above about pH 5.5.
Certain properties of sizing agents are important to control for their
efficient and economical use in making paper. One important property is sizing
eff ciency, i. e., the degree of sizing obtained per unit of sizing agent
added. Sizing
efficiency is determined by the amount and cost of materials used in making
the sizing
agent to obtain a desired sizing characteristic or group of characteristics. A
more efficient
sizing agent results in the desired characteristics at a Iower amount or a
greater efficiency,
and thus, improved papermaking economies. Excess sizing agent can result in
significant
decreases in the paper quality by creating deposits on the papenmaking
machine, causing
defects in the paper. Such deposits also reduce the production rate.
Sizing characteristics are affected by the type of sizing agent used, the
type of paper to which the sizing agent is applied, and many other factors
which have
been the subject of a great deal of work in the past and a continuing body of
work
presently by those in the paper treatment industry. The present invention
relates to sizing
agent compositions in the form of emulsions or dispersions, cationic colloidal
coacenvate
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WO 97!28311 PCTIUS97/01274
dispersion compositions for rosin sizing agents, as well as methods of making
and using
the resulting compositions and dispersions. The term "emulsion" (liquid in
liquid) is
sometimes used in the papermaking industry to refer to what is technically a
"dispersion"
(solid in liquid).
Most sizing dispersions are made by a process involving forming an
emulsion of a hydrophobic sizing agent in an aqueous medium at a temperature
at which
the sizing agent is in a liquid form. Upon cooling to ambient temperature the
emulsion
droplets solidify aad a sizing dispersion results. The process needs an
emulsifier and a
stabilizer in order to process well. Upon application to the wet end of the
papermaking
! 0 process, the particles of the sizing agent, along with alum or its
equivalent as described
above adsorb onto the cellulose fiber. Thermal drying causes the rosin
particles to melt,
distribute along the fiber, and react with the alum or its equivalent. The
fiber then
becomes less wetting, i.e., sized.
Polymers have been used in the past to help with the emulsification and
p also to promote interaction of the sizing particles with cellulose fiber
suspensions.
Starches and water soluble polymers such as polyamidoamines have been used in
this
context.
Various sizing compositions comprising sizing agents and dispersion aids
have been previously disclosed.
20 U.S. Patent 4,240,935 (Dumas), discloses a paper sizing composition
comprising a ketene dimer, an anionic dispersing agent such as sodium lignin
sulfonate,
certain water-soluble cationic resins and water. The cationic resins are
composed of the
reaction products of epichlorohydrin and an aminopolyamide derived from a
dicarboxylic
acid and a polyalkylene polyamine having two primary amino groups and at least
one
'_'S secondary or tertiary amine group. Another group of cationic resins is
the reaction product
of epichlorohydrin and the condensates of cyanamides or dicyandiamide with a
polyalkylene polyamine having a given formula including such compounds as
polyethylene
polyamines, polypropylene polyamines and polybutylene polyamines.
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CA 02245507 2004-08-25
U.S. Patent 4,263,182 (Aldrich) and U_S. Patent 4,374,673 (Aldrich) both
disclose aqueous paper sizing compositions in the form of dispersions
consisting essentially
of finely divided fortified rosin particles, a water-soluble or water-
dispersible cationic
starch dispersing agent for the rosin particles, an anionic surface-active
agent and water.
The distinguishing characteristics between the patents include the use of
different types of
starches. The '182 patent discloses using cationized starches which are
anionic starches
modified by reaction with one of five groups of canonizing resin, or a starch
modified by
reaction with a water-soluble polyamine resin containing epoxy groups. The
'673 patent
uses cationic starches made by reacting starch with compounds containing both
amine
groups and groups reactive with hydroxyl groups of the starch, where the
reaction involves
formation of covalent bonds. Various emulsification and dispersion-forming
steps are
disclosed involving the particular cationic starch dispersing agents.
U.S. Patent 4,657,946 (Rende et al.) discloses paper sizing compositions
comprising alkenyl succinic anhydride sizing agents in an emulsion including
cationic
water-soluble vinyl addition polymers and surfactants which may be anionic,
non-ionic or
cationic where one of the cationic emulsifiers can be
poly(diallyldimethylammonium
chloride).
U.S. Patent 4,861,376 (Edwards etal.) discloses stable, high solids
dispersions of ketene dimer using water-soluble carboxylic acid with cationic
starch,
sodium lignin sulfonate and aluminum sulfate. In some instances, commercial
embodiments
include the post addition of poly(diallyldimethylammonium chloride), as a
promoter, rather
than in the emulsification system.
U.S. Patents 5,318,669 (Dasgupta) and 5,338,407 (Dasgupta) disclose a
process and composition for enhancing the dry strength of paper without
substantially
reducing the paper's softness. Added to a bleached pulp furnish, separately or
together, are
an anionic polymer and a cationic polymer. The anionic polymer may be various
guar
materials and
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CA 02245507 2004-08-25
carboxymethyl bean gum. The cationic polymer may be other types of cationic
guar and
bean gums, cationic acrylamide copolymers and resins based on reactions of
various
polymers with epichlorohydrin.
U.S. Patent 5,338,406 (Smith) discloses a composition and method for
enhancing the dry strength of paper made from pulp of unbleached fibers, and
especially
those containing black liquor. The composition comprises a polyelectrolyte
complex
comprising at least one water-soluble, linear, high molecular weight, low
charge density
cationic polymer having an indicated reduced specific viscosity and charge
density, and at
least one water-soluble, anionic polymer having a charge density less than 5
meq/g. The
cationic polymer may include synthetic polymers such as copolymers of
acrylamide,
including copolymers of acrylamide with diallyldimethylammonium chloride.
Anionic
components may include those normally present in unbleached pulps, such as
solubilized
lignins and hemicelluloses, synthetic anionic polymers and anionically
modified natural
polymers. Sodium lignin sulfonate is mentioned as an example of an effective
anion.
U.S. Patent 5,393,337 (Nakamura et al.) discloses a rosin emulsion sizing
agent for papermaking comprising a fortified or unfortified rosin-epoxy
compound obtained
by reacting a rosin and an epoxy compound. The rosin-epoxy compound is
dispersed in
water with the aid of an emulsifying and dispersing agent. The emulsifying and
dispersing
agent can be various kinds of low-molecular weight surfactants, polymer
surfactants and
protective colloids such as casein, polyvinyl alcohol, or modified starch,
used singly or in
combination.
German Patent Publication No. 4,412,136 A1 (PTS Papiertechnik
Beteiligungsgeselischaft mbH) discloses a paper sizing composition comprising
rosin,
starch and lignosulfonate, but there is no disclosure therein of the formation
of any
coacervate or the appropriate zeta potential used in the present invention.
U.S. Patent 3,677,888 (Economou) discloses a process for manufacturing
paper having improved dry strength, using as the strengthening agent an
ionically self
crosslinked normally coacervating insoluble liquid ampholytic polysalt
composed of
normally water-soluble liquid polyanionic polymer and a normally water-soluble
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CA 02245507 1998-07-31
polycationic polymer, where at least one of such polymers is a weak
electrolyte. The
strengthening agent, having at least one weak electrolye component would not
be able to
have the appropriate zeta potential to act as an emulsifying and dispersing
agent capable
of stabilizing rosin in a rosin sizing composition used to size paper.
Soviet Union Patent Publication No. 1,694,484 discloses a method of
purifying aqueous effluents containing lignosulfonates by adding a solution of
polydimethyldiallylammonium chloride to an effluent containing
lignosulfonates, mixing
and leaving the mixture to settle, and separating the clarified liquid,
followed by other
steps. There is no indication that a coacervate is formed, or that there is a
suitable zeta
potential for using the mixture as an emulsifying agent, a dispersing agent or
a stablilizer
in a paper sizing composition.
Despite the efforts of the industry to develop cost-effective and efficient
paper sizing dispersions having the appropriate desired properties, there are
still many
problems that have been encountered. Many polymers which are used to make
sizing
dispersions have limitations. If, on one hand, the molecular weight is too
small, no final
stabilization is possible because the steric effects. are not there. On the
other hand, if the
molecular weight is high enough for a good steric effect, then ionic
contamination can
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CA 02245507 1998-07-31
cause particle bridging and ensuing rheological problems during storage. In
many cases,
as in the use of naturally derived polymers such as starches, the molecular
weight is not
easily controllable and these hydrocolloids have limited use because of their
great
tendency to bridge. Sizing dispersions must be kept at low solids contents to
prevent
high rheological properties.
This invention uses a coacervate concept. Two oppositely charged
polymers are mixed in such a proportion to produce a third system, a cationic
colloidal
coacervate, which functions as an emulsifier and stabilizer for dispersed
rosin sizing
agents. Using this technique, very little bridging between rosin particles is
observed and
thermal cross-linking of cationic resin adsorbed on neighboring rosin
particles is also
prevented. At the same time, the particle charge, which plays an important
role in
particle deposition on cellulose fiber, can be more precisely controlled, by
controlling the
ratio of the oppositely charged polymers making up the coacervate. The highly
charged
particles provide for better retention of the size in the pulp. Rosin-
coacervate sizing
agents of the present invention have enhanced sizing efficiency and are stable
over
anticipated periods of use and storage.
~ummary of the Invention
One aspect of the present invention relates to a dispersed rosin sizing
composition comprising rosin emulsified and stabilized by a cationic colloidal
coacervate
dispersing agent, the coacervate dispersing agent comprising an anionic
component and a
cationic component, the anionic and cationic components being present in a
proportion
such that the sizing composition has a zeta potential of at least about 20
millivolts.
Another aspect of the present invention relates to a cationic colloidal
coacervate dispersion composition comprising water, a lignosulfonate as an
anionic
component and poly(diallyldimethylammonium chloride) as a cationic component,
the
anionic and cationic components being present in such proportion that the
composition is
cationic, the composition having a zeta potential of at least about 20
millivolts.
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CA 02245507 1998-07-31
Yet another aspect of the present invention relates to a method of making a
cationic rosin sizing dispersion containing rosin and a colloidal coacervate
dispersing
agent, the method comprising the steps: (a) forming a colloidal coacervate
dispersing
agent comprising an anionic component and a cationic component in water; and
(b)
forming an aqueous dispersion of rosin in the colloidal coacervate, the
dispersion having
a zeta potential of at least about 20 millivolts.
Still another aspect of the present invention is a method of producing sized
paper comprising employing in the manufacture of the sized paper a sizing
composition
comprising rosin emulsified and stabilized by a cationic colloidal coacervate
dispersing
I 0 agent, the coacervate dispersing agent comprising an anionic component and
a cationic
component, the anionic and cationic components being present in a proportion
such that
the sizing composition has a zeta potential of at least about 20 millivolts.
A further aspect of the present invention is sized paper sized with a rosin
sizing composition comprising rosin emulsified and stabilized by a cationic
colloidal
I 5 coacervate dispersing agent, the coacervate dispersing agent comprising an
anionic
component and a cationic component, the anionic and cationic components being
present
in a proportion such that the sizing composition has a zeta potential of at
least about 20
millivolts.
20 Drief Description of the Drawing,
Figure 1 is a graph showing the sizing efficiency of two different preferred
products of the present invention. The amount of product used is graphed
against the
sizing efficiency as measured by the Hercules Size Test described below.
25 Detailed Description of the Preferred Embodiments
This invention encompasses cationic coacervate systems which can be
used to emulsify and stabilize rosin sizing dispersions. In general, these
systems
comprise a mixture of an anionic component and a cationic component, which,
when
mixed properly and in the right proportions in water, yield a cationic
colloidal coacervate
30 in an aqueous phase. This colloidal coacervate aqueous phase is then
available for
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A 02245507 1998-07-31
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adsorption. at the liquid/liquid intezfacc of a molten rosin or rosin
dissolved in an organic
phase. Upon shearing the rosin and aqueous phases together, emulsification of
the rosin
within the aqueous medium occurs. Further processing, far exa~-nplc, upon
cooling or
solvent extraction, changas this emulsion into a dispersion (solid in liquid}.
The
coacervate adsorbs at the surface or interface of the organic and aqueous
phases as a
multitude of soft gelatinous particles, thereby increasing the viscosity at
that interface tuzd
yielding excellent stability. The coacervate used in the compositions of. the
present
invention inhibits the diffusion of one liquid droplet into another, while in
the emulsion
form. The charge on the colloidal sizing agent particles can be controlled by
controlling
r
the ratio oFthe anionic and cationic components that rnako up the coacervate.
Each of the anionic and cationic components dots not have to be water-
soluble, as long as they are water-dispersible. For example, one can be
colloidal and the
other soluble. Because no true surfactants (i.e. micelle forming matezials}
are necessary,
even though they can be used, the sizing compositions of the present invention
are more
hydrophobic and can also be of larger particle si;ce. The sizing compositions
thereby
knave better stability and less foaming than prior, surfactant-based rosin
sizing agents,
with the desired viscosity and sizing characteristics.
Rosin
~ The zosin useful far the present invention can 6e any rrtodified or
unmodified rosin suitable for sizing paper, including unfortifred rosin,
fortified rosin and
extended rosin, as well as rosin esters, and mixtures and blends thereof.
The rosin used in this inwcntion can be any of the cocnm.ercially available
types of rosin, such as wood rosin, gurrt rosin, tall oil rosin, and mixtures
of any two or
more, in their crude oz refined state. Tall oil rosin and gum rosin are
preferred. Partially
hydrogenated rosins and polymerized rosins: as well as rosins that have been
treated to
inhibit crystallization, such as by heat treatment or reaction with
formaldehyde, also can
be employed.
_g_
AMENDED SNE~
CA 02245507 2004-08-25
A fortified rosin useful in this invention is the adduct reaction product of
rosin and an acidic compound containing the
C=C-C=O
/
group and is derived by reacting rosin and the acidic compound at elevated
temperatures of from about 150°C to about 210°C.
The amount of acidic compound employed will be that amount which
will provide fortified rosin containing from about 1 % to about 16% by weight
of
adducted acidic compound based on the weight of the fortified rosin. Methods
of
preparing fortified rosin are well known to those skilled in the art. See, for
example,
the methods disclosed and described in U.S. Patents 2,628,918 and 2,684,300.
The
'918 and '300 patents teach the preparation of fortified rosin by heating
rosin together
with an acidic compound as described above. The amount of acidic compound may
range from about one-twentieth to one mol for each mol of rosin.
An alkaline dispersion of the rosin in water is then prepared by forming
a preliminary dispersion of relatively high concentration, after which the
concentrated
dispersion may be diluted to the desired extent. The rosin reacted with the
acidic
compound as described above is heated with an alkali metal base and water and
simultaneously stirred in any suitable reaction vessel at temperatures between
about
140°C and 200°C. The various materials used may be added in
amounts varying from
about 50 to 80% rosin, 4 to 14% alkali, and 6 to 46% water, although it is
preferable to
use the small proportions of rosin as the resulting dispersions may be more
readily
removed from the reaction vessels. The charge is finally cooled down to 60 to
90°C,
depending upon the amount of rosin employed, and is then removed, whereupon it
cools to a consistency varying from a viscous fluid mass to a hard and brittle
solid,
which may be ground to a powder. In all instances, the amount of alkali used
in
sufficient only to partly neutralize the resinous reaction product.
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CA 02245507 2004-08-25
Examples of acidic compounds containing the
C=C-C=O
group that can be used to prepare the fortified rosin include the alpha-beta-
unsaturated
organic acids and their available anhydrides, specific examples of which
include
fumaric acid, malefic acid, acrylic acid, malefic anhydride, itaconic acid,
itaconic
anhydride, citraconic acid and citraconic anhydride. Mixtures of acids can be
used to
prepare the fortified rosin if desired. Thus, for example, a mixture of the
acrylic acid
adduct of rosin and the fumaric acid adduct can be used to prepare the novel
dispersions of this invention. Also, fortified rosin that has been
substantially
completely hydrogenated after adduct formation can be used.
Various rosin esters of a type well known to those skilled in the art can
also be used in the rosin-coacervate dispersion of the present invention.
Suitable
exemplary rosin esters may be rosin esterified as disclosed in U.S. Patents
4,540,635
(Ronge et al.) or 5,201,944 (Nakata et al.). Ronge teaches that colophony
rosins may
be esterified either before or after reinforcement by formaledehyde and/or
a,(3-
unsaturated carbonyl compounds. Esterification is carned out with tertiary
amino
alcohols, preferably at the carboxyl groups of the rosin acids.
The esterification may be carried out with a quantity of 2.5 to 10% by
weight of one or more tertiary amino alcohols, based on the starting rosin
used. This
quantity is preferably 4 to 8% by weight. The tertiary amino alcohols are
furthermore
preferably used in a weight ratio of tertiary amino alcohols to a,~-
unsaturated carbonyl
compounds of 0.5 to 3.1;1. This weight ratio is particularly preferably 0.6 to
1.1:1.
Suitable esterification temperatures are for example those in the range of
170°C to
250°C, and preferably in the range of 200 to 220°C. The
temperature can be kept
constant during the esterification or can be varied within the stated limits.
The
esterification is preferably carried out until the acid number of the reaction
mixture
remains constant.
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CA 02245507 2004-08-25
Nakata teaches that the rosin may be esterified by adding an alkanol
tertiary amine in a ratio of 1.5 to 10 wt% of the total rosin content. A
fortified rosin
produced by adding an a,(3-unsaturated carbonyl compound in a ratio of 3 to 11
wt% of
the total rosin content is mixed with the esterified rosin.
The sizing composition comprises a surfactant represented by formula
(1) shown below in a ratio of 1 to 10 wt% of the solids content of the sizing
composition, and casein in a ratio not exceeding 10 wt% of the solids content
of the
sizing composition. The surfactant and casein are dispersed in a mixture of
the
esterified and fortified rosins.
R-O(CH2CHZ0)~OC-CH-CH-COOM (1 )
X Y
where R represents a C,o_Za alkylphenyl group or a linear or branched alkyl
group; n
represents an integer of 6 to 20; X and Y independently represent H or S03M;
and M
represents sodium, potassium or an ammonium group.
The unfortified or fortified rosin or rosin esters can be extended if
desired by known extenders therefor such as waxes (particularly paraffin wax
and
microcrystalline wax); hydrocarbon resins including those derived from
petroleum
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WO 97/2$311 PCT/US97/01274
The unfortified or fortified rosin or rosin esters can be extended if desired
by known extenders therefor such as waxes (particularly paraffin wax and
microcrystalline wax); hydrocarbon resins including those derived from
petroleum
hydrocarbons and terpenes; and the like. This is accomplished by melt blending
or
solution blending with the rosin or fortified rosin from about 10% to about
100% by
weight, based on the weight of rosin or fortified rosin, of the extender.
Also blends of fortified rosin and unfortified rosin; and blends of fortified
rosin, unfortified rosin, rosin esters and rosin extender can be used. Blends
of fortified
and unfortified rosin may comprise, for example, about 25% to 95% fortified
rosin and
about 75% to 5% unfortified rosin. Blends of fortified rosin, unfortified
rosin, and rosin
extender may comprise, for example, about 5% to 45% fortified rosin, 0 to 50%
rosin,
and about 5% to 90% rosin extender.
The rosin component of the rosin-coacervate sizing composition of the
present invention may vary depending on the type and grade of paper or
paperboard being
sized, the equipment used and whether the size is an internal or surface size.
In general, it
is preferred to use about 10 wt% to about 60 wt% of the rosin component, more
preferably about 20 wt% to about 55 wt%, and still more preferably, about 35
wt% to
about 50 wt% of rosin based on the dry weight of rosin in the aqueous rosin-
coacervate
dispersion composition.
~~e~-vate Components
The coacervate dispersing agent is used to form a stable dispersion of the
rosin in water. The components must be able to form emulsions and dispersions
of
sufficient stability such that there is no separation adversely affecting use
of the
coacervate component or the rosin-coacervate dispersion.
For the rosin sizing agents discussed above for use in the present invention
which contain carboxyl groups, both the anionic component and the cationic
component
used to form the aqueous colloidal coacervate dispersing agent preferably
should have an
acidic pH. The pH preferably should be su~ciently low to avoid ionizing the
carboxyl
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~.. -10-
CA 02245507 1998-07-31
w0 97128311 PCT/US97/01274
groups of the rosin to such an extent that the resulting dispersion will not
be stable. The
plH also preferably should be sufficiently low to avoid forming a salt capable
of
destabilizing the dispersion. As a result, the pH of the components of the
coacervate
dispersing agent, the coacervate dispersing agent itself and the composition
comprising
th.e rosin and the coacervate dispersing agent preferably should be maintained
in an acidic
range, that is, with a pH below about 7, and preferably at a pH of about 2 to
about 7, and
more preferably about 4 to about 6.
The components used to make the coacervate colloidal dispersing agent
will nou~~ be described, other than water. It is preferred to use the minimum
amount of
water that will allow for ease of handling and efficient formation of the
coacervate and
the paper sizing dispersion product.
Although the coacer~.~ate has two oppositely charged components, the
overall charge on the coacervate and the sizing composition is cationic with a
zeta
patential of at least 20 millivolts (hereinafter "mvolts"), for reasons
explained below.
Tlus means that there is enough of the cationic component to form a coacervate
and also
an excess of the cationic component to make sure that the final product is
cationic. In this
way, this process produces sizing dispersions which have higher cationic
charge than
most other processes. Such charge characteristics, if applied properly, can
enhance the
sizing efficiency of the product for sizing paper, including paperboard, with
rosin, and
particularly acid processed paper.
~aionic Cam onent
The anionic component of the coacervate can broadly be any one or a
miixture of anionic colloid or polyelectrolyte or surfactant, individually all
of a type well
known in the art. Examples of anionic colloids are clays, silicas or latexes.
Examples of
anionic polyelectrolytes are polycarboxylates (e.g., polyacrylates,
carboxymethyl
cellulose, hydrolyzed polyacrylamides), polysulfates (e.g., polyvinyl sulfate,
polyethylene sulfate) or polysulfonates (e.g., polyvinyl sulfonate, lignin
sulfonates).
Examples of anionic surfactants are alkyl, aryl or alkyl aryl sulfates, alkyl,
aryl or alkyl
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CA 02245507 1998-07-31
WO 97128311 PCT/LTS97/01274
aryl carboxylates or alkyl, aryl or alkyl aryl sulfonates. Preferably, the
alkyl moieties
have about 1 to about I8 carbons, the aryl moieties have about 6 to about 12
carbons, and
the alkyl aryl moieties have about 7 to about 30 carbons. Exemplary groups
would be
propyl, butyl, hexyl, decyl, dodecyl, phenyl, benzyl and linear or branched
alkyl benzene
derivatives of the carboxylates, sulfates and sulfonates.
The preferred anionic components are polycarboxylates, polysulfates and
polysulfonates. More preferred is a polysulfonate, preferably a ligno- or
lignin sulfonate,
such as the sodium salt, calcium salt, ammonium salt, iron salt or chromium
salt.
A presently more preferred anionic component is sodium lignosulfonate
which has not been neutralized with sodium hydroxide.
Cationic Component
The cationic component of the coacervate can broadly be any one or a
mixture of a polymer, a colloid or a surfactant, individually all of a type
well known in
the art, as long as its or their use would result in a coacervate having the
appropriate zeta
potential discussed herein. Cationic polymers are preferred, such as
polyamine,
polysulfonium or polyamidoamine polymers. The polyamines may be primary
amines,
secondary amines, tertiary amines or quaternary amines or may contain a
mixture of
different strength amine groups such as polyethyleneimine.
The polymers which are particularly useful for this invention include
homopolymers and copolymers having weight average molecular weights greater
than
about 5,000 as determined by size exclusion chromatography. Preferably, the
polymers
have molecular weights below about 500,000 and more preferably on the order of
about
125,000 to about 350,000. The polymers should contain at least about 20%
cationic
functional groups, and preferably, 100% of the functional groups should be
cationic.
Preferred exemplary polymers are a quaternary polyamine, such as
poly(diallyldialkylammonium chloride) wherein the alkyl moiety has 1 to about
6
carbons; a polyvinylamine; and the like.
-12-
CA 02245507 1998-07-31
VVO 97128311 PCT/US97/01274
A present more preferred type of cationic component is a quaternary
polyamine such as a poly(diallyldialkylammonium chloride) wherein the alkyl
moiety has
1 to about 6 carbons, the currently most preferred example being
poly(diallyldimethylammonium chloride), sometimes referred to herein as
"poly(DADMAC)." Other suitable quaternary polyamines include, for example,
polymers of acryloxytrimethylammonium chloride (ATMAC),
methylacryloxytrimethylammonium chloride (MTMAC),
acryloyloxyethyltrimethylammonium chloride,
methacryloyloxyethyltrimethylammonium chloride,
methacryloyloxyethyltrimethylammonium methylsulfate or
methacrylamidopropyltrimethylammonium chloride also including cationic
copolymers
of acrylamide with quaternary polyamines.
The preferred molecular weight would be chosen according to the final
coacervate viscosifying effect. The preferred polymeric cationic components of
the
present invention, and especially the poly(DADMAC) polymers, preferably have
an
intrinsic viscosity of about 0.1 dl/g to about 2 dl/g, more preferably about
0.5 dl/g to
about 1.7 dl/g and even more preferably about 1 dl/g to about 1.3 dl/g. This
corresponds
to a broad range for a solution viscosity of the cationic polymer of about 50
centipoise
{cp) to about 5,000 cp, preferably about i 00 cp to about 5,000 cp, and more
preferably
about 1,000 cp to about 3,000 cp, aII measured at 20% solids. (Brookfleld
viscosities
measured at 60 rpm at room temperature, about 25 °C).
The presently preferred cationic component is poly{DADMAC) available
as R.eten~ 203 from Hercules Incorporated, Wilmington, Delaware. The Reten~
203
product is viscous enough to yield a Brookfield viscosity of about 2,000 cp in
a 20%
solution.
To make the proper coacervate, one preferably should use all or as much
of the water available for the aqueous phase make-up. While the order of
addition of the
components forming the coacervate is not believed to be critical, it is
preferred that the
Ieast viscous of the anionic or the cationic components be added to the water
first. In the
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CA 02245507 1998-07-31
WO 97/28311 PCTILTS97/01274
case where the anionic component is sodium lignosulfonate, sometimes referred
to herein
as "SLS", and the cationic component is poly(DADMAC), the SLS is mixed with
the
water first to form a first mixture. The parameters associated with mixing the
coacervate
components are not critical, as long as they are sufficient to result in a
substantially
homogeneous mixture. Typically and preferably, the mixing is conducted at room
temperature (about 25 ° C) and ambient pressure.
Once the first mixture is well mixed to be sub-stantially homogeneous,
then the most viscous component should be added with vigorous agitation to
form a
second mixture. As before, there are no critical mixing parameters. In this
case where
the anionic component is SLS and the cationic component is poly(DADMAC), the
poly(DADMAC) is added second. The second mixture may visually appear quite
nonhomogeneous but will become more colloidal and homogeneous during
homogenization with the rosin. One can also run the coacervate through a
homogenizes
by itself to render it more homogeneous if desired.
The zeta potential charge on the coacervate dispersing agent will depend
on the ratio of anionic and cationic components making up the coacervate.
Likewise, the
zeta potential on the final dispersion composition comprising rosin and the
coacervate
dispersing agent will depend on the ratio of the anionic and cationic
components of the
coacer4Tate, as well as any residual charged functional groups on the rosin.
The coacervate and rosin-coacervate dispersion charge cannot be zero or
close to neutral. Such systems do not work. To form an effective stable
dispersion, the
charge must be moderately to highly cationic. The zeta potential plays a
strong role in
the stability of sizing dispersions. The zeta potential is the potential
across the interface
of solids and liquids, specifically, the potential across the diffuse layer of
ions
surrounding a charged colloidal particle which is largely responsible for
colloidal
stability. Zeta potentials can be calculated from electrophoretic mobilities,
namely, the
rates at which colloidal particles travel between charged electrodes placed in
the
dispersion, emulsion or suspension containing the colloidal particles. A zeta
potential
value of zero to 10 mvolts will be an indicator of poor stability. A zeta
potential value of
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CA 02245507 1998-07-31
to 19 mvolts is an indicator of some, but usually insufficient stability. A
zeta potential
value of at least 20 mvolts, and preferably 25 to 40 mvolts is an indication
of a moderate
charge with good stability. A zeta potential value of greater than 40 to 100
mvolts or
more normally indicates excellent stability. Thus, in the present invention,
the sizing
composition comprising the rosin and the coacervate must have a zeta potential
of at least
mvolts. Thus, it is preferred that the coacervate and rosin-coacervate
dispersion
charge should be highly cationic, with a preferred zeta potential of at least
25 mvolts and,
more preferably, at least 40 mvolts. This would correspond to better
electrostatic
colloidal stability of the final product. The highly cationic coacervate
produces a final
10 stable dispersion which interacts most strongly electrically with the
cellulose pulp fibers.
The amounts and ratios of the anionic and cationic components used in the
coacervate dispersing agent may vary considerably in view of the different
types of
anionic and cationic components. Factors include the molecular weight and
intrinsic
viscosities of the components, their respective charge densities, the
particular type and
15 amount of rosin to be dispersed in the final rosin-coacervate composition,
the desired zeta
potential, and other factors relating to stability, processing ability and
performance, all of
which can be determined empirically without undue experimentation in view of
this
disclosure.
The final viscosity of the sizing composition should be such that the
20 composition can be easily pumped without any coagulation at about 10% to
about 50%
solids in the dispersion. The final viscosity of the rosin-coacervate sizing
composition
should also be sufficient to prevent stratification of dispersed solid
components. Alum
can be post-added to reduce the viscosity of the dispersion. This is
especially useful
when producing higher concentration compositions which tend to yield higher
viscosity.
Within these broad guidelines, a preferred final rosin-coacervate composition
viscosity
should be from about 6 cp to less than about 250 cp Brookfield viscosity
(measured at 60
rpm) and more preferably, less than about 200 cp. In formulations of the rosin-
coacervate
composition having a solids content of about 35 wt%, the viscosity preferably
is about 15
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CA 02245507 1998-07-31
WO 97!28311 PCT/LTS97/01274
to about 40 cp where the composition has a solids content of about 40 wt%, the
viscosity
preferably is about 30 to about 80 cp.
The amounts and ratios of the coacervate components used to make the
coacervate can be readily determined by back-calculating the amounts desired
in the final
rosin-coacervate dispersion.
To make a coacervate dispersing agent having the beneficial properties
discussed herein, the anionic component is preferably present in an amount of
0. I to
about 2 parts by weight, the cationic component is preferably present in an
amount of 0.1
to about 5 parts by weight, based on the dry weight of the component in the
aqueous
coacervate dispersing agent, the balance being about 33 to about 90 parts by
weight of
water. The cationic to anionic components are preferred to be present in a
ratio greater
than about 0.1 of the cationic component to the anionic component.
A more preferred coacervate dispersing agent contains about 0.2 to about
1.5 parts by weight of anionic component, about 0.2 to about 3.5 parts by
weight of
cationic component, the balance being about 40 to about 80 parts by weight of
water.
The cationic component to anionic component ratio is more preferably about 0.6
to about
3.
A still more preferred coacervate dispersing agent contains about 0.4 to
about 0.6 parts by weight of anionic component, about 0.6 to about 1.3 parts
by weight of
cationic component, with a cationic to anionic component ratio of about 1.2 to
about 2.6.
The balance is wrater in amounts of about 44 to about 64 parts by weight.
Once the aqueous coacervate phase is formed, then the rosin (either
dissolved in a solvent to form an organic phase for a solvent process or
melted in a high
temperature process, typically using high temperature high pressure
homogenization) can
be homogenized into the aqueous phase. The coacervate will perform the
emulsification
and stabilize the resulting dispersion.
The general techniques of forming a paper sizing composition of the
present invention comprising rosin dispersed in the coacervate will now be
described,
although the caacervate dispersing agent and the sizing agent including the
rosin and the
~~~"dc~fi~,,i : ..
' f .F ~..p,!:,~,..~
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CA 02245507 1998-07-31
WVO 97128311 PCT1US9710I27~1
coacervate dispersing agent may be prepared by any other process suitable to
make the
desired product.
Generally, in the solvent process or method, the composition of the present
invention is formed as a dispersion comprising the steps {i) dissolving the
rosin in an
organic solvent immiscible in water to form an organic phase; {ii) forming an
aqueous
phase of the cationic colloidal coacervate dispersing agent by mixing with
water the
anionic component and the cationic component in such proportions arid with
sufficient
shear to form a cationic colloidal coacervate; (iii) homogenizing the organic
phase and
the: aqueous phase coacervate dispersing agent to form an emulsion; and (iv)
removing
the organic solvent from the emulsion to form the dispersion. Steps (i) and
(ii) may be
reversed in order or done simultaneously. Moreover, processing may be batch
processing, continuous processing or a combination thereof
More specifically, in preparing the aqueous rosin dispersion of this
invention by the solvent process, the rosin is first dissolved in a water-
immiscible organic
solvent, such as benzene, xylene, methylene chloride, chloroform, or 1,2-
dichloropropane. Other solvents compatible with the desired end product and
paper
sizing operation can also be used. Mixtures of two or more solvents can be
used if
desired. The selected solvent will also be non-reactive with the components of
the
aqueous dispersion to be subsequently prepared.
A mixture is prepared with the organic phase rosin solution and the
coacenTate aqueous phase dispersing agent of cationic and anionic components.
The
essentially unstable aqueous mixture is then subjected to sufficient shear to
provide an
essentially stable emulsion. Sufficient shear is conveniently accomplished by
means of a
homogenizer, although the coacervate dispersing agent of the present invention
allows the
use of considerably less sophisticated equipment, such as a Waring~ blender.
Nevertheless, on a commercial scale, passing, at least once, the unstable
aqueous mixture
through a homogenizer at ambient temperature under a pressure on the order of
from
about 7 kglcmz (100 p.s.i.g.) to about 560 kglcm2 (8,000 p.s.i.g.), preferably
about140
- I7-
CA 02245507 2004-08-25
kg/cm2 (2,000 p.s.i.g.) to about 210 kg/cm2 (3,000 p.s.i.g.) will provide an
essentially
stable emulsion.
Subsequently, the organic solvent component of the emulsion is
removed from the emulsion, as by stripping using vacuum distillation, and
there is
S provided an essentially stable aqueous dispersion of rosin particles. These
procedural
steps are described in U.S. Patent No. 3,565,755. The '755 patent teaches that
a stable
oil-in-water emulsion is prepared by homogenization, with salts of rosin and
salts of
rosin adducts, sometimes called "saponified material", serving as emulsifying
agent.
Substantially all solvent is removed from the emulsion, preferably by
distillation, either
at atmospheric pressure or subatmospheric pressure, such that an aqueous
suspension
that is substantially homogeneous and which has excellent stability for
prolonged
periods of time is formed. The saponified material now serves as a dispersing
agent in
the aqueous suspension.
The general technique used for the high temperature process or method
will now be described for making the sizing composition of the present
invention in the
form of a dispersion. This general method comprises the steps: (i) heating the
rosin to
a temperature sufficient to melt the rosin; (ii) forming an aqueous phase of
the cationic
colloidal coacervate dispersing agent by mixing with water the anionic
component and
the cationic component in such proportions and with sufficient shear to form a
cationic
colloidal coacervate; (iii) mixing the molten rosin with the aqueous
coacervate
dispersing agent to form a mixture; (iv) subjecting the mixture of step (iii)
to sufficient
shear to form an emulsion; and (v) cooling the emulsion of step (iv) to form
the
dispersion. Steps (i) and (ii) may be reversed in order or done simultaneously
and
mixing step (iii) may be combined with emulsifying step (iv). Moreover,
processing
may be batch processing, continuous processing or a combination thereof.
More specifically, in preparing dispersions of this invention by the high
temperature process, the rosin is heated past its melting point, preferably to
at least
-18-
CA 02245507 2004-08-25
about 135°C, and more preferably to about 165°C to about
180°C, where it is less
viscous. Preferably, the molten rosin is pumped, as is the coacervate, to a
homogenizer where they are intimately mixed and emulsified at a temperature of
from about 80°C to about 195°C, preferably about 125°C to
about 145°C, to form
an essentially stable aqueous emulsion. Sufficient shear is conveniently
accomplished by means of a homogenizer. Thus, passing, at least once, the
mixture
through a homogenizer under a pressure on the order of about 70 kg/cm2 (1,000
p.s.i.g.) to about 560 kg/cm2 (8,000 p.s.i.g.), and preferably about 140
kg/cm2
(2,000 p.s.i.g.) to about 210 kg/cmz (3,000 p.s.i.g.) will provide an
essentially
- 18a -
CA 02245507 1998-07-31
'7V0 97!28311 PCTlCTS97/0127AG
stable emulsion which forms a stable dispersion upon cooling. The pressure
selected is
within the skill of the art.
The following information relates to an exemplary presently preferred
embodiment in which the anionic component is sodium lignosulfonate (SLS), such
as
Wanin~ S, from LignoTech USA, Vargon, Sweden, and poly(DADMAC), such as
Reten~ 203, from Hercules Incorporated, Wilmington, Delaware, and having 19.3%
solids, and an intrinsic viscosity of 1.3-I.5 dl/g. The anionic component may
be present
in .an amount of 0.1 wt% to about 2 wt%, and the cationic component may be
present
from about 0.1 wt% to about 5 wt%, and the ratio of cationic component to
anionic
IO component is greater than about 0.1. Rosin may be present in an amount of
about I O
wt% to about 60 wt%. All weight percents are calculated on the basis of the
percentage
of the dry weight of the component in the aqueous rosin-coacervate
composition.
Preferred amounts are about 0.2 wt% to about 1.5 wt% of the anionic
component, about 0.2 wt% to about 3.5 wt% of the cationic component, at a
cationic to
anionic component ratio of about 0.6 to about 3.0, with rosin present in an
amount of
about 20 wt% to about 55 wt%.
More preferred amounts of the ingredients are about 0.4 wt% to about 0.6
wt% of the anionic component, about 0.6 wt% to about 1.3 wt% of the cationic
component, at a cationic to anionic component ratio of about 1.2 to about 2.6,
with rosin
preaent in an amount of about 35 wt% to about 50 wt%.
The amounts and ratios may change based on the use of anionic
components Other than SLS and cationic components other than Reten~ 203. Use
of
these ingredients in the indicated ranges and ratios should produce a stable
emulsion at
sufficient viscosity for efficient homogenization and production of a stable
rosin-
coacervate dispersion composition. By using a lower molecular weight
poly(DADMAC),
such as one having an intrinsic viscosity of about 1.0 dl/g, higher cationic
polymer
contents can be obtained without having viscosity problems. This provides the
ability to
produce more cationic systems.
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CA 02245507 1998-07-31
WO 97128311 PCT/LTS97/01274
Emulsification with this coacervate system is also quite energetically
favorable. Even a Waring~ blender can serve the purpose for emulsification,
although
homogenization works better, as demonstrated using a Tekmar~ homogenizer
(Tekmar
Company, Cincinnati, Ohio) and even better using a Manton-Gaulin~ homogenizer
(APV Gaulin Inc., Wilmington, Massachusetts}.
Other additives, such as alum used to reduce viscosity, defoamers,
biocides and other preservatives, can be added to the rosin-coacervate
dispersion of the
. present invention in amounts and using techniques known to those in the
papermaking
industry.
The sizing composition in the form of the dispersion is employed in the
manufacture of paper to be sized with the composition, typically as an
additive to a
papermaking furnish used to manufacture the sized paper. However, the
composition of
the present invention can also be applied as a surface treatment or external
sizing agent by
applying it to the surface of the paper after the paper is formed in a size
press or other
I~ suitable application equipment using application techniques well known to
those skilled
in the art.
As noted above, rosin-based sizing compositions are used with
papermaker's alum or other equivalent aluminum compounds. The alum or its
equivalent
can be incorporated into the sizing composition of the present invention or,
more
typically, the alum or its equivalent can be applied as a separate component
to the pulp
when the rosin-coacervate dispersion of the present invention is used as an
internal size or
when it is applied as an external, surface size. When the alum or its
equivalent is mixed
with the rosin-coacervate composition of this invention, the alum or its
equivalent may be
present in amounts up to about 50 wt% based on the weight of the rosin-
coacervate
composition including the alum. The amount of alum or its equivalent to be
used is
determined based on the type of alum or its equivalent used, the grade of
paper being
treated, the amount of sizing agent being applied, and other factors well
known to those
skilled in the art. In unbleached papermaking systems, for example, when added
to the
pulp as a separate component, alum or its equivalent is normally used at
addition levels
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CA 02245507 2004-08-25
WO 97/28311 PCT/US97/01274
less than 1 wt%, based upon the dry weight of the pulp, and typically, at
levels of about
0.1 wt% to about 0.8 wt%.
The rosin-coacervate composan of the present invention is used in
amounts based on the desired sizing requirements of the customer, depending
upon the
required degree of sizing, the grade of paper, the type of pulp furnish used
to make the
paper, and other factors well known and easily determined empirically by those
skilled in
the art. In general, the least amount of sizing agent is used to obtain the
desired sizing
specifications.
When the sizing composition is applied as an internal additive during
papermaking, it is preferred to use about 0.025 wt% to about 1 wt% based on
the dry
weight of the pulp.
When the composition of the present invention is employed as an external
surface size, it is preferred to use about 0.01 wt% to about 1 % of the
composition based
on the dry weight of the paper web.
:5
One well-recognized test for measuring sizing performance is the Hercules
Size Test, described in Pulp and Paper Chemistry and Chemical Technology, J.P.
Casey,
Ed., Vol. 3, p. 1553-1554 (1981) and in TAPPI Standard T530. The Hercules Size
Test
determines the degree of water sizing obtained in paper by measuring the
change in
reflectance of the paper's surface as an aqueous solution of dye penetrates
from the
opposite surface side. The aqueous dye solution, e.g., naphthol green dye in
1% formic
acid in Example 13 described below, is contained in a ring on the top surface
of the paper,
and the change in reflectance is measured photoelectrically from the bottom
surface.
Test duration is limited by choosing a convenient end point, e.g., a
reduction in reflected light of 20%, corresponding to 80% reflectance, in
Example 13
described below. A timer measures the time (in seconds) for the end point of
the test to be
reached. Longer times correlate with increased sizing performance, i.e.,
resistance to
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CA 02245507 1998-07-31
WO 97!28311 PCT/LJS97/01274
water penetration increases. Unsized paper will typically fail at 0 seconds,
lightly sized
paper will register times of from about 1 to about 20 seconds, moderately
sized paper
from about ZI to about 150 seconds, and hard sized paper from about 151 to
about 2,000
seconds.
EXAMPLES
The present invention will now be described with reference to the
follo~.ving specific, non-limiting Examples.
Unless otherwise noted in the Examples, the rosin-coacervate composition
was prepared based on the solvent process as described above. The steps were
carried out
at room temperature (about 25 ° C} and ambient pressure, except as
otherwise noted.
Specific processing details, where important, are specified, as are the
appropriate
properties and results of the studies in each of the Examples.
As used in the Examples, all percentages of components are weight
percentages of the components on a dry basis, of the aqueous rosin-coacervate
composition, unless otherwise noted. Percentages of water are by weight based
on the
weight of the aqueous rosin-coacervate composition.
Example 1
Preparation of a rosin size with a coacervate containing
0 5% SLS and I 2% Reten~ 203 using; a Manton-Gaulin~ homogenizes
Organic phase rosin: 307 g of a 6.5% combined fumaric acid (CFA) rosin
dissolved in
450 g of methylene chloride.
Aqueous phase coacervate: 5.3 g of SLS (sodium lignosulfonate, Wanin~ S, from
LignoTech USA, Vargon, Sweden), 65.3 g of Reten~ 203 polymer (19.3% solids,
intrinsic viscosity 1.3 dl/g and 600 g deionized water.
The SLS was dissolved first, then the Reten~ 203 polymer was added.
The pH was 4.2. The aqueous phase was mixed using the high setting on a
Tekmar~
homogenizes (laboratory model No. SD-45) while adding the organic phase. This
took
15 seconds. This pre-mix was then passed through a Manton-Gaulin~ homogenizes
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CA 02245507 1998-07-31
'CVO 97/28311 PCTILTS97/0127~C
(model No. 15MS TBA) twice at 2I0 kg/cm2 (3,000 p.s.i.} pressure. Some
dilution water
w,as introduced to help start the homogenizer. The resulting emulsion was
treated in a
rotary evaporator to remove the methylene chloride solvent at a temperature
above its
boiling point (40°C). The resulting emulsion was cooled to room
temperature, at which
a 5 time a rosin-coacervate dispersion was formed that had the following
properties:
Total solids: 25.3%
Particle size: 578 nm (after passing through a 100 mesh sieve)
Rheology: rpm viscosity, cn
6 ?0
I2 65
30 56
60 49
pH: 2.8
The rheology data indicate that the dispersion has good stability, based on
the small difference between the highest and lowest viscosity readings at the
various rpm
levels. Comparison and quantification are readily performed by taking the
logarithm of
the ratio of the lowest to highest reading. In this case, log(49/70) _ -0.155.
The
calculated value can vary from zero to -1. The closer the calculated value is
to zero, the
more stable the product is. Values less than -0.3 (that is, values such as -
0.4, rather than
values such as -0.2) indicate that the dispersion may exhibit instability
problems.
A sample of the sizing dispersion prepared in this Example was aged in an
oven at 32°C for 4 weeks and the viscosity was measured each week. The
following 60
rpm viscosities and pH were measured using a Brookfield~ LVT Viscometer
(Brookfield
Engineering Laboratories, Inc., Stoughton, Massachusetts) and a pH meter:
1 week weeks weeks 4 weeks
vise, cp: 47 47 42 39
pH: 2.8 2.8 2.8 2.8
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WO 97/28311 PCT/US97/01274
These lower viscosity results indicate good stability. The lower viscosity
indicates that there is no bridging between the rosin particles and the
dispersion is
pumpable. The product did not gel under storage conditions.
The charge on the sizing particles in the dispersion was determined as the
zeta potential (Z.P.) measured with a Lazer Zee~ Meter model 501 (Pen Kem
Inc.,
Bedford Hills, New York). This was done by diluting 1 or 2 drops of the
dispersion in
100 mls of deionized water and adjusting the pH with NaOH or H2S04 to the
values
indicated below-, except for pH 5.8, which was the pH of the composition
without
adjustment with acid or base. The following results show the cationic
character of the
new sizing composition. The high zeta potential value at pH 5.8 is due to no
addition of
acid or base.
pH: ~.l 4!7 5~8 8-00 ~.0
Z.P., mvolts +36.0 +43.2 +52.2 +35.5 +28.3
As can be seen by the positive Z.P. readings, the sizing particles are
cationic, even in the alkaline range. The Z.P. readings indicated good to
excellent
stability of the dispersion. Also, no post addition of alum or any other
dispersing agent is
needed to preserve stability.
xample 2
Preparation of a rosin size with a coacervate containing 0.5%
~T ~ and 0 6% Reten~ 203 using a Manton-Gaulin~ homogenizer
The same techniques were used as in Example 1.
Organic phase rosin: 307 g of a 6.5% combined fumaric acid (CFA) rosin
dissolved in
450 g of methylene chloride.
Aqueous phase coacervate: 5.3 g of SLS (Wanin~ S), 32.6 g of Reten~ 203 (I9.3%
solids) and 600 g deionized water. The SLS was dissolved first, then the
Reten~
polymer was added.
The following properties of the rosin-coacervate product were observed:
Total solids: 30.3%
Particle size: 557 nm (after passing through a 100 mesh sieve)
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CA 02245507 1998-07-31
WVO 97/28311 PCTlUS97/01274
Rheology: ~-pm viscosi, . cn
6 60
12 45
30 36
60 33
log(33/60) _ -0.26, indicating good stability
pH: 2.8
A sample was aged in an oven at 32°C for 4 weeks and the viscosity was
measured each week. The following 60 rpm viscosities and pH were observed,
indicating
excellent stability:
week 2 weeks weeks 4 weeks
vise, cp: 33 34 35 31
pI-i: 2.8 2.8 2.8 2.8
The charge on the particles was determined as the zeta potentials measured
with a Lazer Zee~ Meter model 501. This was done by diluting 1 or 2 drops of
the
dispersion in 100 ml of deionized water and adjusting the pH with NaOH or
H2S04. The
following results show the cationic character of the new sizing composition.
The Z.P.
readings greater than 40 in the acidic range, the range desired for this
particular sizing
composition, indicated excellent stability.
pH: ~ 4-66 $_0 9-00
Z.P., mvolts +45.3 +44.0 +20.4 +17.9
Egample 3
No potymer, rosin onlx
An attempt was made to emulsify rosin only, as in Example 3, but without
Reten~ polymer, anionic component or alum. The product failed rapidly. The
emulsion
broke quickly into 3 layers immediately after being made and could not even be
stripped
- of solvent.
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CA 02245507 1998-07-31
WO 97/Z8311 1'CT/U897/01274
Example 4
reparation lfailurel without the anionic component
A sample of rosin size was prepared using the solvent process following
the techniques of Example 1. The following formulation was used:
S Organic phase rosin: I36 g of a S.4% combined fumaric acid rosin dissolved
in 204.5 g of
methylene chloride
Aqueous phase: 21 g Reten~ 203 (19.3% solids)
403.3 g deionized water
44.5 g of SO% alum
Procedure: The Reten~ polymer was mixed with the deionized water. The pH of
this
solution was S.7S. It was lowered to 4.2 with SN HCI. The water phase was
mixed with
the organic phase and passed through a Manton-Gaulin~ homogenizes. The
emulsion
destabilized while stripping off the solvent at 70°C.
1 S Example 5
1% Reten~ 203 fails without anionic component
An attempt was made to form a dispersion of rosin sizing agent and
Reten~ 203 without the lignosulfonate anionic component following the general
techniques of Example 1, as follows.
Organic phase rosin: 300 mls methylene chloride and 409 g of a 6.S% CFA rosin
Aqueous phase: 807 g deionized water
14 g Reten~ 203 (19.3% solids)
A. Emulsification was attempted in a Manton-Gaulin~ homogenizes
using two passes. The solvent was stripped at 60°C and a sizeable
quantity of rosin
2S material separated out. The system failed while standing.
B. A similar experiment was run using the Telcmar~ homogenizes and
some alum in the water phase:
Organic phase rosin: 20S g of 6.S% CFA rosin in 136 g methylene chloride
Aqueous phase: 403 g deionized water
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7 g Reten~ 203 (19.3% solids)
44.5 g of 50% alum
The organic and aqueous phases were homogenized in a Tekmar~
hamogenizer. The emulsion looked fine but failed during stripping at 55
°C.
- 5 Comparing Examples 4 and 5, in Example 4, the pH was lowered to what
was believed to be a more preferred pH. In Example 5, the pH of 5.8 was not
adjusted.
These Examples demonstrate that emulsions made without the anionic component
are not:
stable.
Example 6
Factorial (statistical) experiment
on SLS-Reten~ 203 sizing emulsions
A statistical experiment was run with two variables: the SLS {Wanin~ S}
an:d the Reten~ 203 {19.3% solids) concentration. Otherwise, the techniques
used in this
example are those used in Example 1, except as otherwise noted.
Organic phase rosin: 307 g of 6.5% CFA rosin in 450 g of methylene chloride
Aqueous phase: The SLS concentration was varied from 0.5% to 3% and the Reten~
polymer concentration from 0.6% to 1.2%. The mid-point was 1.75% SLS and
0.9% Reten~ polymer.
The following results were observed:
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Reten~ Viscosity Diameter
Designation % SLS 203 Result (cp) (nm)
A 0.5 0.6 stable 45 1065
B 0.5 1.2 stable 70 911
C 3 0.6 failed
D 3 1.2 failed
E 1.75 0.9 less 30 3174
stable
As can be seen, there are preferred ratios of the anionic and cationic
components of the coacervate for making the rosin size dispersions of this
invention.
Although it would seem that the SLS would play the role of the emulsifier, it
is the total
coacervate, at the proper ratio and concentration of the cationic and anionic
components,
which ultimately controls the final stability and the emulsification action.
Using 3% (dry
basis) SLS did not produce stable systems. Even using 1.75% SLS was only
marginal.
Using too much cationic polymer (Reten~ 203) produced unacceptably viscous
systems.
Other experiments showed that the more preferred lower limit of SLS using SLS
(Wanin~ S) and Reten~ 203 as the coacervate components is about 0.4% SLS to
still
produce effective emulsification. Other types and/or molecular weights, degree
of
cationic charge and viscosity of the components could be used to obtain the
desired final
properties without undue experimentation in view of this disclosure.
Exam~~le 7
Effect of varied Reten~ 203 concentration
Following the general procedures of Examples 1 and 6, samples of rosin-
coacervate sizes were made at 0.5% SLS (Wanin~ S) and 0.5, 0.4, and 0.3%
Reten~ 203, .
as indicated in the following table:
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0.5% Reten 0.4% Reten 0.3% Reten
Organzc Phase: grams rg ams rg ams
rosin (6.5% CFA) 102.25 102.25 102.25
methylene chloride 150 150 150
Aqueous base:
Wanin~ S (SLS) 1.75 1.75 1.75
Reten~ 203 (19.3%) 9.07 7.25 5.44
deionized water X00 200 X00
Total 463.07 461.25 459.44
%SLS (talc) 0.56 0.56 0.57
/aReten~ (talc) 0.56 0.45 0.34
Reten~/(calc) SLS ratio1.0 0.8 0.6
Total (talc) % Solids 33.8 33.9 33.9
A concentration of 0.4%
Reten~ 203 was the lowest
concentration in this
pa~~ticuiar coacervate g these ular ingredients which
dispersing agent usin partic would give
an emulsion which did not abruptly
break up.
Example 8
Effect of higher solids
Two formulations, A and B, were made following the general techniques
of Examples 1 and 6, using the Tekmar~ laboratory bench homogenizer at the
higher
Reten~ 203 concentrations and having the components and amounts as indicated
below.
The target solids were 40%. The following characteristics of the dispersions
were
achieved:
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0.6% Reten 1.2% Reten
Or~:anic Phase: r s ams
rosin 102.25 102.25
rnethylene chloride 150 1 SO
Aqueous Phase: ,
Wanin~ S (SLS) 1.75 1.75
Reten~ 203 ( 19.3 %) 10.88 2 i .76
deionized water 159.15 149.74,
Total 424.03 425.5
%SLS (calc) 0.64 0.64
%Reten~ (calc) 0.77 1.52
Reten~ISLS ratio {calc) 1.2 2.4
Total % Solids (calc) 38.7 39.3
Particle size (nm) 1981 2143
Viscosity {60 rpm-cp) 54 140
The higher concentration of n~ 203 in this Example caused the
the Rete
viscosity to increase substantially but the samples were acceptable and stable
to heat
aging at 32°C for four weeks.
example 9
J~ffect of neutralized SLS
The techniques of the previous Examples were used, except as noted, to
determine the effect of using a neutralized SLS product, rather than the
acidic SLS
(Wanin~ S) product used in Examples 1 through 8.
The 0.5% SLS and 0.6% Reten~ 203 system was prepared using different
SLS products (Lignosol~ SFX-65, Ufoxane~ 2, both from LignoTech USA,
Rothschild,
Wisconsin). Lignosol~ SFX-65, when dissolved in water, had a pH of 7.2, which
shows
that it is a pre-neutralized product. Ufoxane~ 2 has an even higher degree of
neutralization (SLS/water pH of 9.0). Other components and amounts are listed
below:
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Lignosol~ SFX-65 Ufoxane~ 2
grams rams
rosin (6.5% CFA) 102.25 102.25
methylene chloride 150 150
' SL~S 1.75 1.75
Reten~ 203 (19.3%) 10.88 10.88
dei:onized water 238.8 23g.g
Total 503.68 503.68
%SLS (calc) 0.49 ~ 0.49
%Reten~ {talc) 0.59 0.59
Reten~/SLS ratio (calc) 1.2 1.2
Total % Solids (calc) 30.0 30.0
The Tekmar~ homogenizer was used to make the emulsion. The
emulsion had poor stability while stripping and large amounts of solids could
be filtered
out. When this experiment containing Lignosol~ SFX-65 was repeated with a pH
adj ustment of the aqueous phase to pH 4.0, instability was still encountered.
The
composition using Ufoxane~ 2 also failed.
Tt is believed that the neutralization of the SLS causes the rosin's carboxyl
groups to ionize, resulting in a lower zeta potential on the rosin-coacervate
particles
produced using neutalized SLS components. When the pre-neutralized Lignosol~
SFX-
65 product was Iater acidified, a salt was formed which results in an unstable
product.
Example 10
Lower molecular weight poly(DADMAC~
A lower molecular weight poly(DADMAC) having an intrinsic viscosity
of 1.0 dI/g, 20% solids, pH of 6, viscosity at 20% solids of 700 cp, was used
instead of
Reten~ 203 to make a rosin size. Other than as indicated, the techniques in
the
experiments of this Example were the same used in the previous Examples. The
amounts
of components were as follows:
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Formulation
Organic phase: grams
rosin (6.5% CFA) 102.25
methylene chloride 150
Aqueous phase: '
Wanin~ S (SLS) 1.75
poly(DADMAC) (20% solids) 14 ,
deionized water ~?
Total 500
%SLS (calc) 0.50
%Reten~ (calc) 0.77
Reten~/SLS ratio {calc) 1.54
Total % Solids (calc) 30.5
In this case, test tube scale experiments demonstrated that emulsions could
be made rather easily at 0.6 to 1.0% poly(DADMAC). Using 0.5% Wanin~ S SLS and
0.$% of the lower molecular weight poly(DADMAC), a stable 29.6% solids rosin
sizing
dispersion could be made with a Tekmar~ homogenizer, by mixing the aqueous
phase
using the high setting while adding the organic phase. This took 2 minutes.
Exam In a lI
Constant Reten~ 2Q3/SLS ratio systems, ratio = 0.6/0.5 = 1.2
The same procedures, except as noted below, were used in this Example as
in the previous Examples. Samples having the components and amounts listed
below
were made at a constant coacervate cationic/anionic component ratio of 1.2,
but at
increasing total coacervate concentrations to see the effect on product
processing and
characteristics.
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Formulation A ~ C D E
O~ a~nic phase: rg~
rg
ams
rg
ams
rg
ams
grams
rosin (6.5% CFA) 29.21 29.21 29.21 29.21 29.21
' S methylene chloride 43 43 43 43 43
Aaueous hn ase:
Wanin~ S (SLS) 0.25 0.5 0.75 1 1.25
Reten~ 203 1.55 3.11 4.66 6.22 7.77
deionized water 68-999967-1818 6S-3838 63.37 61.52
Total 143 143 143 142.8 142.75
%SLS (calc) 0.25 0.50 0.75 1.00 i.25
%Reten~ (calc) 0.30 0.60 0.90 1.20 1.50
Reten~/SLS ratio (calc) 1.2 1.2 1.2 1.2 i.2
Tc~tal % Solids (calc) 29.8 30.3 30.9 31.5 32.0
Th.e dispersions were made
by pouring the organic
phase into the aqueous
phase under
high shear using a Tekmar~ homogenizer
as
in
Example
10.
Each
sample
was
homogenized for 2 minutes. The
following
product
characteristics
were
determined:
Designation: A B C D E
Diameter, nm 1900 1659 2926 2056 973
Z;.P. mvolts +29.0 +30.0 +28.0 +30.3 +29.7
Viscosity, cp 13 18 32 29 37
The zeta potential measurement was a simple one point measurement of a
drop diluted in 100 mls of deionized water. The pH of such a measurement was
normally
5.6 which is not a more preferred pH for this cationic rosin sizing product. A
more
preferred pH is about 4.5 to 4.8. This measurement does show good control,
however, by
keeping the coacervate component ratio constant.
All these systems were quite stable and only the viscosity was increased
within acceptable limits by going to higher coacervate concentrations. This
demonstrates
that the amounts of the components may be varied within the appropriate ratios
discussed
. above.
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example 12
Constant Reten~ 203 ~~$ ratio spstems. ratio = 1.210.5 = 2.4
This is essentially the same experiment as in Example 11, except a higher
cationic/anionic component ratio is used. The components and amounts in the
composition are as follows:
!formulation ~ ~ C
Or ag nic hp ase: grains rg; rg grams ram
ams ams
rosin (6.5% CFA) 43.82 43.82 43.8243.82 43.82
methylene chloride 65 65 65 65 65
Aqueous phase:
Wanin~ S (SLS) 0.38 0.75 1.13 1.5 1.88
Reten~ 203 4.66 9.33 13.9918.65 23.32
deionized water 101.14 ~.1 91-060686.03 $098
Total 215 215 215 215 215
%SLS (calc) 0.25 0.50 0.75 1.00 1.25
%Reten~ (calc) 0.60 1.20 1.80 2.40 3.00
Reten~/SLS ratio (calc) 2.37 2.40 2.39 2.40 2.39
Total % Solids (calc) 30.1 30.9 31.8 32.6 33.5
The results of measurements are
like those in Example 11 as
follows:
Designation: A B C D E
Diameter, nm 2407 1720 2021 2483 3067
Z.P., mvolts +28.5 +34.2 +48.9 +48.4 +49.5
Viscosity, cp 22 33 49 75 95
This particular ratio still forms good emulsions but is more sensitive to
viscosity. A higher cationic charge can also be obtained as indicated by the
zeta potential
values.
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example 13
S~jgg efficiencx
The sizing efficiency was measured, using a pilot laboratory paper
forming machine, of two products of the present invention having the
compositions noted
. 5 below:
~ormulatnon Low Reten~ Higlh Reten~
Organic phase: g~"yams g
rosin {6.5% CFA) 306.75 306.75
methylene chloride 450 450
~,ueous phase:
Wanin~ S (SLS) 5.25 5.25
Reten~ 203 32.64 65.28
deionized water 600 600
Total 1394.64 1427.28
%SLS (calc) 0.56 0.54
%Reten~ {calc) 0.67 1.29
Reten~?ISLS ratio (calc) 1.2 2.4
Total % Solids {calc} 33.7 33.2
Fine paper was run using a 70/30
hardwood/softwood bleached blend
at 40
pound basis weight. The rosin-coacervate sizing agents of this invention
were added to
the pulp at the wet end of the Alum (aluminum sulfate) was added
machine. separately in
an amount of 0.75 wt% based on
the dry pulp weight. Sizing level
was varied from 0.2%
to 0.5% on the pulp fiber and
the sizing efficiency was measured
using the Hercules Size
Test described above. Two sizing samples were tried, one with a lower
cationic/anionic
component ratio {1.2) of 0.6% Reten~ 203/0.5% SLS and one with a higher
cationiclanionic component ratio {2.4) of 1.2% Reten~ 203/0.5% SLS.
It is important for understanding the concept of this invention that one
realizes that a strong effect on sizing efficiency is relatable to the
coacervate portion of
the product. There may be other important variables, but according to this
invention, the
coacervate can play a major role in the final efficiency of the product.
The results are shown in the graph of Figure 1.
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The lower, dashed line on the graph shows a relatively lower, but still
acceptable sizing efficiency when a lower amount of the cationic component is
used,
compared to the upper, solid line representing the higher sizing efficiency of
the product
of the present invention using a higher amount of the cationic component. It
is believed
that the greater sizing e~ciency exhibited by the product with the greater
proportion of ,
the cationic component is consistent with the concept that the rosin-
coacervate of the
present invention having a higher cationic charge adsorbs better on the fiber
surface of
the pulp to render the paper hydrophobic.
The present invention may be embodied in other specific forms without
departing from the spirit or essential attributes thereof and, accordingly,
reference should
be made to the appended claims, rather than to the foregoing specification, as
indicating
the scope of the invention.
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