U.S. patent application number 10/365770 was filed with the patent office on 2003-08-14 for styrene copolymers combined with metallic species in deposition inhibition.
This patent application is currently assigned to Huntsman Petrochemical Corporation. Invention is credited to Nguyen, Duy T., Parr, Rodney W..
Application Number | 20030150578 10/365770 |
Document ID | / |
Family ID | 46281989 |
Filed Date | 2003-08-14 |
United States Patent
Application |
20030150578 |
Kind Code |
A1 |
Nguyen, Duy T. ; et
al. |
August 14, 2003 |
Styrene copolymers combined with metallic species in deposition
inhibition
Abstract
Provided herein are compositions useful for inhibiting the
formation of gummy residues on equipment in processing operations
which liberate tiny adhesive particles having a tendency to
agglomerate into larger particles and/or films. The compositions
comprise a complex or adduct formed from styrene/methacrylic acid
copolymer and calcium ions. The compositions according to the
invention may be added to a processing system at any point, either
upstream or downstream from the location at which residues are
formed. Compositions according to the invention may be applied by
spray techniques.
Inventors: |
Nguyen, Duy T.; (Austin,
TX) ; Parr, Rodney W.; (Doncaster, AU) |
Correspondence
Address: |
Legal Department
Huntsman LLC
P. O. Box 15730
Austin
TX
78761
US
|
Assignee: |
Huntsman Petrochemical
Corporation
Austin
TX
|
Family ID: |
46281989 |
Appl. No.: |
10/365770 |
Filed: |
February 13, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10365770 |
Feb 13, 2003 |
|
|
|
09776985 |
Feb 5, 2001 |
|
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Current U.S.
Class: |
162/199 |
Current CPC
Class: |
D21C 9/086 20130101;
D21H 21/02 20130101; C08K 3/24 20130101 |
Class at
Publication: |
162/199 |
International
Class: |
D21F 001/32 |
Claims
We claim:
1) An aqueous composition of matter which consists essentially of:
a) water; and b) the complex formed between: i) a copolymer
component comprising a water soluble anionic form of
styrene/methacrylic acid copolymer in which the copolymer has a
styrene content in the range of 10.0% to 45.0% by weight based upon
the total weight of the styrene/methacrylic acid copolymer,
including every hundredth percentage therebetween, and wherein said
copolymer component has a molecular weight in the range of 2,000 to
30,000 including every molecular weight therebetween; and ii) a
metal component comprising an aqueous solution containing at least
one multivalent cation selected from the group consisting of:
calcium, magnesium, strontium, barium, nickel, copper, tin, cobalt,
iron, zinc, or mixtures thereof, wherein the ratio of the copolymer
component to the metal component is in the range of between 1:4 to
1:500 on a weight basis.
2) A composition according to claim 1 wherein the ratio of the
copolymer component to the metal component is in the range of
between 1:10 to 1:400 on a weight basis.
3) A composition according to claim 1 wherein the ratio of the
copolymer component to the metal component is in the range of
between 1:15 to 1:300 on a weight basis.
4) A composition according to claim 1 wherein said copolymer
component has a styrene content in the range of 15.0% to 38.0% by
weight based upon the total weight of the styrene/methacrylic acid
polymer, including every hundredth percentage therebetween.
5) A composition according to claim 1 wherein said copolymer
component has a molecular weight in the range of 5,000 to 25,000
including every molecular weight therebetween.
6) An aqueous composition of matter which consists essentially of:
a) water; and b) the complex formed between: i) a copolymer
component comprising a water soluble anionic form of
styrene/methacrylic acid copolymer in which the copolymer has a
molecular weight in the range of 2,000 to 30,000 including every
molecular weight therebetween; and ii) a metal component comprising
an aqueous solution containing at least one multivalent cation
selected from the group consisting of calcium, magnesium,
strontium, barium, nickel, copper, tin, cobalt, iron, zinc or
mixtures thereof, wherein the ratio of the copolymer component to
the metal component is in the range of between 1:4 to 1:500 on a
weight basis.
7) A composition according to claim 6 wherein the ratio of the
copolymer component to the metal component is in the range of
between 1:10 to 1:400 on a weight basis.
8) A composition according to claim 6 wherein the ratio of the
copolymer component to the metal component is in the range of
between 1:15 to 1:300 on a weight basis.
9) A composition according to claim 6 wherein the molecular weight
of the copolymer is in the range of 5,000 to 24,000, including
every molecular weight therebetween.
10) A composition according to claim 6 wherein the molecular weight
of the copolymer is in the range of 9,000 to 18,000, including
every molecular weight therebetween.
11) A composition according to claim 6 wherein the molecular weight
of the copolymer is in the range of 11,000 to 15,000, including
every molecular weight therebetween.
12) An aqueous composition of matter which consists essentially of:
a) water; and b) the complex formed between i) a copolymer
component comprising a water soluble form anionic of
styrene/methacrylic acid copolymer in which the copolymer has a
styrene content in the range of 10.0% to 45.0% by weight based upon
the total weight of the styrene/methacrylic acid copolymer,
including every hundredth percentage therebetween; and ii) a metal
component comprising an aqueous solution containing at least one
multivalent cation selected from the group consisting of calcium,
magnesium, strontium, barium, nickel, copper, tin, cobalt, iron,
zinc, or mixtures thereof, wherein the ratio of the copolymer
component to the metal component is in the range of between 1:4 to
1:500 on a weight basis.
13) A composition according to claim 12 in which the styrene
content of the copolymer is in the range of between about 15.0% and
35.0%, by weight based upon the total weight of the
styrene/methacrylic acid copolymer, including every hundredth
percentage therebetween.
14) A composition according to claim 12 in which the styrene
content of the copolymer is in the range of between about 18.0% and
30.0%, by weight based upon the total weight of the
styrene/methacrylic acid copolymer, including every hundredth
percentage therebetween.
15) A composition according to claim 12 in which the styrene
content of the copolymer is in the range of between about 21.0% and
27.0%, by weight based upon the total weight of the
styrene/methacrylic acid copolymer, including every hundredth
percentage therebetween.
16) A process for preventing deposition of pitch, resin, stickies,
lignin, and other residues on processing equipment in processes in
that such species are present which comprises the steps of: a)
providing an aqueous composition of matter which comprises: i) a
copolymer component comprising a water soluble anionic form of
styrene/methacrylic acid copolymer; and ii) a metal component
comprising an aqueous solution containing at least one multivalent
cation selected from the group consisting of calcium, magnesium,
strontium, barium, nickel, copper, tin, cobalt, iron, zinc, or
mixtures thereof, and b) introducing an effective deposition
inhibiting amount of said aqueous composition into a process stream
in which pitch, resin, lignin, and other residues are liberated,
wherein the concentration of the copolymer component of said
aqueous composition in said process stream is in the range of
between 0.5 parts per million to 500 parts per million by weight
based upon the weight of said process stream.
17) A process according to claim 16 wherein the concentration of
the copolymer component of said aqueous composition in said process
stream is in the range of between 2.0 parts per million to 150
parts per million by weight based upon the weight of the process
stream
18) A process as in claim 16 wherein the metal component is present
in said process stream in any amount between 4 times the amount of
the copolymer component and 500 times the amount of the copolymer
component.
19) A process as in claim 17 wherein the metal component is present
in said process stream in any amount between 4 times the amount of
the copolymer component and 500 times the amount of the copolymer
component.
20) A process according to claim 16 wherein said multivalent cation
is selected from the group consisting of: calcium and magnesium;
and wherein the molecular weight of the copolymer is in the range
of 2,000 to 30,000 including every molecular weight therebetween
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This Application is a continuation-in-part of U.S.
application Ser. No. 09/776,985 which was filed on Feb. 5, 2001 and
is currently still pending, the entire contents of which are herein
incorporated by reference thereto.
TECHNICAL FIELD
[0002] This invention relates to compositions of matter useful in
causing tacky surfaces or materials to be rendered less tacky. More
particularly, the invention relates to compositions useful in
preventing coagulation in solutions comprising minute particles of
tacky materials. The compositions and processes detailed herein are
especially well-suited for use in paper mills and other employments
where solutions containing sticky particles come into contact with
process equipment and have the propensity to cause fouling of the
surfaces of such equipment by agglomeration of such particles.
BACKGROUND
[0003] The formation of troublesome agglomerations of sticky bodies
in aqueous solutions used in processing various chemical materials
has been observed in various systems for some time. Such formation
is a particular noteworthy problem in the paper and pulp
manufacturing industry, regardless of the method used to pulp raw
wood.
[0004] In general terms, there are two methods which are recognized
by those in the paper science arts for making a pulp from which
many useful products may be derived. The qualities of the pulp
produced by each process renders them each useful in particular
end-use applications.
[0005] The first of such processes is a chemical process, which is
known as the "Krafft" process, and involves chemically treating
wood chips and the like at an elevated temperature with a strongly
alkaline aqueous solution of sodium sulfide in order to produce a
pulp having most of the lignins and resins removed from the
interstices between the individual fibers.
[0006] The second of such processes is known as mechanical pulping
and entails forcing de-barked logs against a grinding stone or
metal disks called "refiners" in order to produce a pulp. From the
mechanical process is produced a pulp product having more of the
lignins and the resins remaining in the pulp than in the Krafft
process. There are other processes employed for pulping, which
contain some character of each of the chemical and the mechanical
processes. In one variant, wood chips are treated with steam in the
presence of caustic soda for a prescribed time prior to being
subject to grinding in the mechanical process. In another variant,
wood chips are impregnated with sulfur compounds prior to the
steaming.
[0007] Regardless of the method used to produce a pulp, all pulping
processes are carried out in the presence of water, which is
capable of acting as a carrier for all of the materials present
during the pulping. Some of the materials include as aforesaid, the
resins and lignins, which are capable of existing in the form of
soaps. One particularly troublesome property of these materials is
that while soluble at high pH levels, they tend to exist in the
form of particulate precipitates in the presence of divalent metal
ions, such as the alkaline earth metals. The nature of these
particulate precipitates is that they are generally very sticky on
their exterior and thus have a propensity towards formation of
larger gummy globules and/or films on equipment with which they
come into contact. This problem is typically manifest at the point
at which the soluble resin and lignin first come into contact with
a source of di-valent metal cation, which in the case of the
chemical process is usually in the first washer which the pulp
encounters after leaving the digesters because this is where fresh
rinse water containing di-valent metal ions enters such a chemical
pulping system. The initial deposition of such particles is often
in the form of a rough film. As deposition continues, thick
incrustations form, particularly on exposed edges to such an extent
as to interfere with the operation of the pulp mill equipment.
Eventually, portions of, or even the whole operation must be shut
down to enable cleaning of the machinery, which is a costly and
time-consuming endeavor.
[0008] Another class of materials known as "stickies" are
troublesome in pulping and like operations. Whereas pitch, resin,
and the like arises from the processing of virgin pulp, stickies
arise from secondary fibers. Stickies are described in U.S. Pat.
No. 4,956,051 which is incorporated in its entirety herein by
reference thereto.
[0009] The prior art is replete with the attempts of various
workers to prolong or even eliminate the formation of such deposits
on paper mill equipment. For example, U.S. Pat. No. 3,992,249 which
is incorporated herein in its entirety by reference thereto,
teaches a process for inhibiting the deposition of adhesive pitch
particles onto the surface of pulp-making equipment, prior to
beating, from the water with which a cellulose fiber suspension
having a content of the particles is being washed. The process
comprises washing the suspension in a pulp washer containing an
aqueous solution of an anionic polymer containing at least about 25
mol percent, but not more than about 85 mol percent, of
hydrophobic-oleophilic linkages. Hydrophobic oleophilic linkages
suitable for this employment are selected from the group comprising
styrene, isobutylene, methylstyrene, allyl stearate, octadecyl
acrylate, octadecene, dodecene, n-octadecylacrylamide, vinyl
stearate and vinyl dodecyl ether. Also present in the solution is
at least about 15 mol percent, but not more than about 75 mol
percent, of hydrophilic acid linkages. Hydrophilic acid linkages
suitable for this use are selected from the group comprising
acrylic acid, methacrylic acid, maleic acid, itaconic acid,
acrylamidoacetic acid, maleamic acid and styrenesulfonic acid. A
pitch-polymer complex of the particles and the polymer is formed by
their admixture, which is removed with the water used to wash the
cellulose fiber suspension. Thus, substantially all of the
pitch-polymer complex is separated from the cellulose fiber
suspension. The amount of the polymer used is in the range of about
0.5 to 100 parts by weight per million parts by weight of the
suspension.
[0010] U.S. Pat. No. 4,184,912 which is incorporated herein in its
entirety by reference thereto, teaches a method of inhibiting pitch
formation in paper mill pulp systems which comprises adding to such
systems, at a point prior to where pitch deposits normally occur,
at least 0.5 ppm, based on the weight of the pulp, of a composition
comprising varying amounts of surfactants. One such system contains
varied amounts of: Non-ionic surfactant; Anionic Dispersant;
Anionic Polymer having molecular weight less than 100,000. In
another embodiment, the surfactants comprise: an ethoxylated
phenol; an alkyl-substituted naphthalene sulfonate; and an acrylic
acid co-polymer (molecular weight between 5,000 and 40,000).
[0011] U.S. Pat. No. 6,143,800 which is incorporated herein in its
entirety by reference thereto, discloses compositions and methods
for inhibiting deposition of organic contaminants in equipment
associated with a pulping operation which entails the addition of a
composition comprising: a dinonyl sulfosuccinate anionic
surfactant; and a multivalent cation to the system wherein the
weight ratio of said dinonyl sulfosuccinate anionic surfactant to
multivalent cation ranges from about 1:4 to about 1:100. A
composition embraced by the above-mentioned description is added to
the pulp or the surfaces of pulping mill machinery in an effective
deposition inhibiting amount.
[0012] However, each of the methods of the prior art has its own
drawbacks. For example, the teachings of U.S. Pat. No. 3,992,249
uses calcium to form pitch and subsequently adds a sodium salt
copolymer to prevent further deposition of unwanted solids such as
pitch, stickies, and the like. U.S. Pat. No. 4,184,912 and
6,143,800 claim the use of surfactants to control the deposition of
stickies, pitch, and the like, but when the fiber slurry is diluted
with white water from the paper-making machinery the surfactants
tend to de-sorb from the surfaces of the stickies, pitch, and like
particles. As a result the particles once again become susceptible
to agglomeration with themselves and other particles, and are hence
once again susceptible to re-deposition.
SUMMARY OF THE INVENTION
[0013] The present invention provides an aqueous composition of
matter which comprises a copolymer component comprising a water
soluble anionic form of styrene/methacrylic acid copolymer and a
metal component. The copolymer preferably has a styrene content in
the range of about 10.0% to about 45.0% by weight based upon its
total weight, and has a molecular weight in the range of about
1,000 to about 100,000. The metal component comprises an aqueous
solution containing at least one multivalent cation selected from
the group consisting of: calcium, magnesium, strontium, barium,
nickel, copper, tin, cobalt, iron, zinc, or mixtures thereof. The
ratio of the copolymer component to the metal component is in the
range of between 1:4 to 1:500 on a weight basis.
[0014] In order to use a composition according to the invention,
one introduces an effective deposition inhibiting amount of said
aqueous composition into a process stream in which pitch, resin,
lignin, and other residues exist or are liberated. The
concentration of the copolymer component in an aqueous composition
according to the invention in the process stream is in the range of
between about 0.5 parts per million to 500 parts per million by
weight based upon the weight of the process stream. The metal
component content in a composition according to the invention is
calculated based upon the amount of copolymer present. One
preferred form of the invention employs a copolymer component
concentration of between about 10 ppm to 50 ppm based upon the
amount (weight basis) of the process stream treated and the metal
component is calcium ion, present at between about 100 ppm to 500
ppm, also based upon the amount (weight basis) of the process
stream treated.
DETAILED DESCRIPTION
[0015] The present invention provides a composition of matter which
comprises at least one styrene/methacrylic acid copolymer in
combination with a multi-valent metal cation, which compositions
according to the invention are preferably aqueous solutions
comprising these components. To provide a composition according to
the invention, one first provides the copolymer component as an
aqueous solution of its alkali metal salt. Suitable metals include
lithium, sodium, potassium, rubidium, etc. A preferred ratio of
styrene to methacrylic acid in the copolymer is 40:60 on a weight
basis; however, copolymers having any content of styrene in the
range of 10.0% to 45.0%, by weight based upon the total weight of
the styrene/methacrylic acid polymer, including every hundredth
percentage therebetween, are suitable for use in the present
invention.
Styrene/Methacrylic Acid Copolymer and Water Soluble Salt
Thereof
[0016] The preparation of styrene/methacrylic acid copolymers is
straightforward and is known in the art. One method for preparing
such copolymers useful in the present invention involves fitting a
3-necked IL flange flask with a mechanical stirrer, heating mantle,
thermometer, reflux condenser, addition inlet, and provision for
maintaining an inert atmosphere within the reaction vessel, such as
a nitrogen inlet. The flask is charged with three hundred thirty
six (336) grams of isopropanol and one hundred twelve (112) grams
of water. Heating is commenced under stirring and slow nitrogen
sweep until a gentle reflux is achieved, at about 80 deg.
Centigrade. A first stream comprising eighty (80) milliliters of a
5% aqueous sodium persulphate solution was slowly added to the
contents of the refluxing contents of the flask simultaneously with
a second stream comprising a liquid mixture of 70.4 grams of
styrene and 105.4 grams of methacrylic acid, over the course of
about 2 hours. Following the addition, the temperature was
maintained at reflux for an additional 2 hours to ensure complete
reaction. Then, an additional ten (10) milliliters of 22% sodium
persulphate was added, and the temperature maintained at reflux for
one additional hour to provide a styrene/methacrylic acid
copolymer.
[0017] To prepare the sodium salt of the aforesaid polymer, the
flask from the above was set up for distillation by affixing a head
and condenser thereto. The flask is heated until the azeotrope of
isopropanol and water begins to distill, and then two hundred
thirteen (213) grams of a 23% (wt.) aqueous solution of sodium
hydroxide is slowly added to the flask during the distillation at a
rate which is approximately equal to the rate at which the
azeotrope is being distilled. The temperature of the contents of
the flask are monitored, and when the temperature reaches 100-105
deg., the flask is allowed to cool to 50 degrees centigrade and the
pH is adjusted to a level between about 8 and 10 using aqueous
NaOH, and to a total solids content of between about 30 and 35%
(wt.) as determined by evaporation of all of the water from a
sample of known weight and dividing the weight of the solids
remaining by the total initial weight and converting to a
percentage by multiplication by 100.
[0018] The above procedure affords an aqueous solution comprising
the sodium salt of styrene/methacrylic acid copolymer, to which may
be added a multivalent metal ion in order to afford a composition
according to the invention which is useful as an anti-coagulation
additive for pitch and resinous materials in paper mills and other
systems.
[0019] Although the styrene/methacrylic acid ratio in the above
preparatory method is about 40:60, copolymers of styrene and
methacrylic acid having other ratios are also useful herein as the
copolymer component from which an anti-coagulant additive may be
formed. The copolymers having any content of styrene in the range
of 10.0% to 45.0%, by weight based upon the total weight of the
styrene/methacrylic acid polymer, including every hundredth
percentage therebetween, are suitable for use in the present
invention. These polymers having varied amounts of styrene and
methacrylic acid are made by altering the relative amounts of each
of the components in the second stream referred to in the
preparatory method above. For example, when a copolymer having a
styrene to methacrylic acid ratio of 30:70 is desired, the second
stream comprises 52.70 grams of styrene and 123.06 grams of
methacrylic acid. When a copolymer having a styrene to methacrylic
acid ratio of 20:80 is desired, the second stream comprises 35.15
grams of styrene and 140.61 grams of methacrylic acid.
[0020] Although the water-soluble salt of the copolymer whose
preparation is described above as being the sodium salt as formed
by the addition of aqueous sodium hydroxide in the final step in
which the alcohol is removed by distillation, other basic
substances which produce a water-soluble polymer are suitable as
employment as neutralizing agents herein. Such basic substances
include without limitation alkaline aqueous solutions or
suspensions of other soluble metal cations, metal oxides,
carbonates, etc., including without limitation, basic carbonates of
any of the alkali metals or monovalent iron, the basic oxides of
any of the alkali metals or monovalent iron, ammonia, or alkyl
amines including primary, secondary and tertiary amines provided
that a solution of the copolymer results after the admixture and
heating. In cases where suspensions of oxides are used, a longer
heating time may be necessary to effectuate solution, depending
upon the particle size of the basic substance.
[0021] The final polymers produced according to a procedure such as
that described above may have molecular weights of any molecular
weight value in the range of about 1,000 to about 100,000, with
molecular weights having any value in the range of 1,500 to 50,000
being preferred, with molecular weights having any value in the
range of about 2,000 to about 30,000 being most preferred.
The Multivalent Metal Component
[0022] Compositions prepared in accordance with and useful in the
preferred form of the present invention are prepared from combining
a solution of a copolymer component with a solution or suspension
of a metal cation component. The multivalent metal component (or
"metal cation" component) useful for admixture with the soluble
copolymer component in accordance with the present invention may
contain any metal cation which reduces the contact angle of the
copolymer sufficiently to modify the surface of pitch, stickies, or
the like from hydrophobic to hydrophilic. It is preferred that a
multivalent cation used in the present invention is capable of
existing and is present in a di-valent form. Thus, any metal for
which stable divalent compounds are known to exist is suitable for
use in the present invention. Such metals include, without
limitation, magnesium, calcium, strontium, barium, nickel, copper,
tin, cobalt, iron, and zinc. It is preferred that the multivalent
metal is a divalent metal. It is more preferred that the
multivalent metal is a metal selected from the group consisting of
the alkaline earth metals. It is most preferred that the
multivalent metal is selected from the group consisting of calcium
and magnesium.
The Anti-Coagulant Compositions
[0023] Although a solution of a multivalent metal ion and a
solution of a soluble copolymer of styrene and methacrylic acid may
both be added separately to an aqueous system, it is preferred that
these materials be mixed with one another prior to their being
added to the system. This is because it is believed that the two
species interact with one another to form an adduct or complex
which possesses anti-coagulant properties for resin, pitch, lignin,
and other bodies present in these aqueous systems. The present
invention is concerned with preventing the deposition of particles
derived from lignin, pitch, resin, and the like onto various
articles and pieces of process equipment and these terms are
intended herein to refer to any material which can be considered to
form a sticky residue including without limitation: natural resins
(fatty and resin acids, fatty esters, insoluble salts, sterols,
etc.); defoamers (oil, EBS, silicate, silicone oils, ethoxylates);
sizing agents (rosin size, ASA, AKD, hydrolysis products, insoluble
salts); coating binders (PVAC, SBR); Waxes, Inks, Hot melt glues
(EVA, PVAC, amorphous polyolefins); contact adhesives (SBR, vinyl
acrylates, polyisoprene, and the like). From a physical standpoint,
such deposits typically form from microscopic particles of
materials having adhesive outer surfaces in the stock which
accumulate on papermaking or pulping equipment. Such deposits are
often found on stock chest walls, paper machine foils, Uhle boxes,
paper machine wires, wet press felts, dryer felts, dryer cans, and
calendar stacks. Such particles formed from resins, pitch, lignins
and the like are usually particles of visible or nearly visible
size.
[0024] To form a composition according to a preferred form of the
invention, one begins with a first solution that contains a water
soluble salt or solution of the copolymer, and a second solution
that contains a soluble aqueous solution of the divalent metal
selected. A vessel containing either of the solutions is caused to
undergo agitation, and a stream of the second solution is slowly
added to the first. Upon mixing of the two solutions, a clear
solution is formed. It is this final clear solution that results
from admixture of the soluble copolymer solution with a multivalent
metal ion that is useful as an anti-coagulant in accordance with a
preferred form of the present invention. Such a final solution
containing an anti-coagulant may be simply added to the pulp mill's
water system at any location which is upstream from the point where
the pitch, resin, or lignin-derived material first comes into
contact with calcium ions (typically from an outside water source
used as rinse or process water) because calcium ions can react with
pitch, resin, or lignin-derived material to form microscopic sized
particulate precipitates, which particulate precipitates are
capable of agglomerating with one another to form undesirable films
and gummy precipitates.
[0025] As mentioned, the compositions of the present invention are
effective at inhibiting the deposition of organic contaminants in
all papermaking systems regardless of the type of process employed
including without limitation Krafft, acid sulfite, mechanical pulp
and recycled fiber systems. Deposition in the brown stock washer,
screen room, and Decker system in Krafft papermaking processes can
be inhibited according to the teachings of the invention. The
present compositions can be utilized to inhibit deposition on all
surfaces of any papermaking system from the pulp mill to the reel
of the paper machine, including those process contents having any
pH in the range of about 3 to about 11, and under a variety of
other system conditions including temperatures, ionic strengths,
solids content, etc. More specifically, the styrene/methacrylic
acid compositions effectively decrease the deposition not only on
metal surfaces but also plastic and synthetic surfaces such as
machine wires, felts, foils, Uhle boxes, rolls and headbox
components. Further, the compositions of the present invention may
be used with other pulp and papermaking additives including without
limitation starches, whiteners such as titanium dioxide, defoamers,
wet strength resins, sizing aids, and any other material known to
those skilled in the art as being useful as a functional additive
in a papermaking system.
[0026] The compositions of the present invention can be added to
the paper-making system at any stage. They may be added directly to
the pulp furnish or indirectly to the furnish through the headbox.
In another form of the invention, an anti-coagulant composition
prepared in accordance with the teachings herein may be sprayed
directly onto pieces of equipment which are desired to be protected
from the gummy precipitates or films. Also, a composition according
to the invention may be sprayed onto areas upon which are already
deposited gummy residues from pitch, resin, lignin, etc. Such areas
may include without limitation wires, press felts, press rolls and
other deposition-prone surfaces. When added by spraying techniques,
the composition is preferably diluted with water to a satisfactory
inhibitor concentration. Thus, a composition according to the
invention may be added to any point in a pulp and papermaking
system. Spraying may be conducted using a spray bar, atomizer, or
other means known by those skilled in the art of providing a spray
to a surface.
[0027] The compositions of the present invention can be added to
the papermaking system neat, as a powder, slurry or in solution;
the preferred primary solvent including without limitation, water.
The compositions may be added specifically and only to a furnish
identified as contaminated or may be added to blended pulps. The
compositions may be added to the stock at any point prior to the
manifestation of the deposition problem and at more than one site
when more than one deposition site occurs. Combinations of the
above additive methods may also be employed by feeding the pulp
millstock, feeding to the paper machine furnish, and spraying on
the wire and the felt simultaneously.
[0028] It is preferred that the weight ratio of styrene/methacrylic
copolymer to multivalent cation in the complex formed according to
the invention ranges from about 1:4 to about 1:500. More
preferably, this ratio is in the range of between about 1:10 to
about 1:400. It is most preferred that the weight ratio of
styrene/methacrylic copolymer to multivalent cation in the complex
formed according to the invention ranges from about 1:15 to about
1:300.
[0029] In use in an aqueous system in which there exist chemical
species derived from resins, lignins, pitch, etc. which are capable
of forming microscopic particles in the presence of calcium, which
particles have a propensity to agglomerate to form an insoluble
fouling, gummy film on plant equipment and the like, to which a
composition according to the invention is to be added, the total
concentration of the styrene/methacrylic acid copolymer present
which is effective for preventing agglomeration of gummy residues
on plant equipment and the like is between about 0.5 parts per
million to 500 parts per million of styrene/methacrylic acid
copolymer, based upon the weight of the pulp or solution to which a
composition according to the invention is added. It is more
preferred that this concentration is in the range of about 2.0
parts per million to 100 parts per million of styrene/methacrylic
acid copolymer, based upon the weight of the pulp or solution. It
is most preferred that the total concentration of copolymer present
is in the range of between 5 and 80 parts per million based upon
the weight of the pulp or solution to which it is added.
[0030] For purposes of the present invention, the term "an
effective deposition inhibiting amount" is defined as that amount
which is sufficient to inhibit deposition of residues derived from
pitch, resin, lignin, and the like in pulp and papermaking systems.
The effective amount to be added to the papermaking system depends
on a number of variables including the pH of the system, hardness
of the water, temperature of the water, additional additives, and
the organic contaminant type and content of the pulp. Generally,
from about 0.5 parts to about 150 parts of the inventive
composition per million parts of pulp is added to the papermaking
system. Preferably, from about 2 parts to about 100 parts of the
inventive composition are added per million parts of pulp in the
system.
[0031] The data set forth below were developed to evaluate test
results obtained through use of the present invention. However, it
quickly became evident that a synergistic result was discovered
with respect to the contact angle measurements and the amount of
calcium ion present. The following data are included as being
illustrative of the present invention and should not be construed
as being delimitive thereof in any way.
Surface Tension and Contact Angle Measurements
[0032] Contact angle measurements provide direct information about
the hydrophobicity of a surface which is coated with a sticky
substance, such as an agglomerated residue derived from a pitch,
lignin, resin, etc. These measurements are thus capable of
providing information about the change in the hydrophobicity of a
surface as surface-active materials are adsorbed and/or de-sorbed
at the surface. A lower contact angle indicates that the surface is
less susceptible to deposition of such gummy residues. A zero
contact angle is most preferred. Surface tension provides
information about the surface activity of the surfactants. A lower
surface tension indicates that the surfactant can emulsify and
therefore stabilize the pitch dispersion more effectively. A stable
dispersion will, in turn, minimize or prevent deposition.
[0033] A well-known Wilhelmy-type technique was used to obtain
surface tensions and receding contact angles of a solid immersed in
the solutions containing different treatments. The Kruss K-12
Tensiometer was used. The experiment was performed at room
temperature (23.degree. C.). A clean platinum plate with exactly
known geometry is brought in contact with liquid and the force
acting on the plate is measured via a microbalance. The surface
tension of the liquid is calculated from the measured force:
.lambda.=P/(L.times.COS .theta.)
[0034] in which .lambda.=surface tension; P=measured (Wilhelmy)
force; and L=wetted length. In this equation, .theta. is the
contact angle between the tangent at the wetting line and the plate
surface. For the determination of the surface tension, the
roughened and cleaned platinum plate is used and its contact angle
is zero.
[0035] A packaging tape made from a styrenebutadiene rubber and
vinylic esters and a polyester film such as MYLAR.RTM. (trademark
of E. I. DuPont de Nemours), were used as a solid substrate for
contact angle measurements. For the testing, a clean solid
substrate was clamped on a film stage, then placed in a glass test
cell. The test solution was added to the cell and the whole test
cell was placed inside the chamber of a goniometer. The substrate
was in contact with the solution for 30 minutes and after which an
air bubble was positioned on the underside of the substrate with an
inverted tip. Contact angle provides information about the
hydrophobicity of a simulated surface comprising a pitch, resin, or
lignin and the change in the hydrophobicity as surface-active
materials are adsorbed and/or de-sorbed at the surface. A lower
contact angle is indicative of the surface being less susceptible
to stickies and/or pitch deposition. Surface tension provides
information about the surface activity of the surfactants. A lower
surface tension indicates that the surfactant is likely to adsorb
at the contaminant's surface and thereby, stabilizing the pitch
dispersion more effectively. A stable dispersion will minimize or
prevent deposition. The results of this testing are reported in
Table I The following abbreviations are used in the examples which
follow: STYMMA 1=styrene methacrylic copolymer (30 wt % styrene/70
wt % methacrylic acid); STYMMA 2=styrene methacrylic copolymer (10
wt % styrene/90 wt % methacrylic acid); STYMMA 3=styrene
methacrylic copolymer (40 wt % styrene/60 wt % methacrylic acid);
STYMAA 4=styrene methacrylic copolymer (50 wt % styrene/50 wt %
methacrylic acid); STYMMA 5=styrene methacrylic copolymer (40 wt %
styrene/60 wt % methacrylic acid but higher molecular weight than
STYMMA 3); PVA=polyvinyl alcohol (88% hydrolysis); and DI
H.sub.2O=de-ionized water.
1TABLE I Surface Tension and Contact Angle Measurements at
23.degree. C. of solutions having varied copolymer concentrations
and calcium content in the complex. Surf. ID copolymer Ca Tension
Contact Angle No. Substance level ppm ppm (dyne/cm) (degrees) 1 DI
H.sub.2O 0 0 72.8 63.2 (MYLAR .RTM.) 70.9 (Tape) 2 DI H.sub.2O + 0
50 72.8 63.2 (MYLAR .RTM.) Ca 70.9 (Tape) 3 STYMMA 1 1 0 -- 70.4
(Tape) 4 STYMMA 1 50 0 72.5 62.4 (MYLAR .RTM.) 5 STYMMA 1 1000 0 --
56.8 (MYLAR .RTM.) 6 STYMMA 1 0.5 50 -- 41.2 (Tape) 7 STYMMA 1 1 50
-- 32.4 (Tape) 8 STYMMA 1 10 50 54.6 21.6 (MYLAR .RTM.) 9 STYMMA 1
50 50 50.23 13.1 (MYLAR .RTM.) 10 STYMMA 3 1 50 -- 26.0 (Tape) 11
PVA 1 0 -- 51.9 (Tape) 12 PVA 3 0 -- 45.9 (Tape)
[0036] The results presented in Table I demonstrate that the STYMMA
polymers operate synergistically with calcium towards minimization
of the contact angle. Contact angle measurements are shown in
example 2, at 50 ppm calcium and in the absence of copolymer for
both substrates of Tape and MYLAR.RTM.. Looking at examples 3-5
shows the contact angle measurements for varying levels of
copolymer but in the absence of calcium, and from the examples 2-5
it is clear that for both cases where copolymer is present in the
absence of calcium and where calcium is present in the absence of
copolymer, the magnitude of the contact angle measured is about the
same in both cases, in the range of about 55-70 degrees. However,
as is evident from the examples 6-10, when calcium and copolymer
are both present, the contact angle drops dramatically, in evidence
of the heretofore unknown synergy between styrene/methacrylic acid
copolymers and calcium ion towards altering the hydrophobicity of a
simulated surface comprising a pitch, resin, or lignin and the
change in the hydrophobicity as surface-active materials are
adsorbed and/or de-sorbed at the surface. The most dramatic effect
is evident from comparing examples 9 and 4, which shows the
dramatic effect of the presence of calcium on the decrease in the
surface tension and contact angle.
Standard Tape Detackification Test
[0037] This test method measures the effect of chemical additives
on contact adhesion. An adhesive tape (2".times.4") and a polyester
coupon (2".times.4") were treated with the test solution (600
gram). The solution contained in a 600 mL beaker is placed in a
water bath with agitation and heated to the desired temperature.
After 30 minutes of immersion, the tape and coupon are removed from
the solution and pressed to 10,000 lb force for 1 minute and then
the peel force is then measured. A reduction of peel force
indicates the level of detackification of the adhesive surface. The
more the adhesive surface is detackified, the less the deposition
potential of particulate residues derived from pitch, lignin,
resin, etc. would be. The % control or detackification is
calculated by the following equation:
% detackification=[(untreated force)-(treated
force)].times.100/untreated force
[0038] Results of this testing are set for the in Table II
below:
2TABLE II Standard Tape Detackification Test Peel % Sample Dosage
Ca Temp. Force detacki- No. Substance (ppm) (ppm) .degree. C. (lbf)
fication 1 DI H.sub.2O 0 50 5.13 0 2 STYMAA 1 0.15 0 50 4.50 2.2 3
STYMAA 1 0.15 5 50 4.00 13.0 4 STYMAA 1 0.15 10 50 1.07 76.7 5
STYMAA 1 0.15 30 50 0.59 87.2 6 STYMAA 1 0.15 50 50 0.28 94.5 7
STYMMA 1 0.15 100 50 0.20 95.7 8 STYMMA 1 0.15 500 50 0.31 93.3 9
STYMAA 1 0.10 100 50 0.93 79.8 10 STYMAA 1 0.25 100 50 0.03 99.3 11
DI H.sub.2O 0 0 25 6.1 0 12 STYMAA 1 0.25 0 25 6.02 0 13 STYMAA 1
0.25 10 25 3.40 33.7 14 STYMAA 1 0.25 30 25 2.00 61.0 15 STYMAA 1
0.25 50 25 1.77 65.5 16 STYMAA 1 0.25 100 25 0.68 86.7 17 STYMAA 1
0.25 200 25 0.52 89.9 18 STYMAA 1 0.25 500 25 0.36 93.0 19 PVA 1 25
0.63 87.7 20 STYMAA 3 0.15 50 50 0.34 93.4 21 STYMAA 5 0.15 50 50
1.58 69.2 22 STYMAA 4 0.15 50 50 3.57 43.7 23 STYMAA 2 0.15 50 50
1.56 69.6
[0039] These results confirm the results set forth in Table I that
the efficacy of styrene methacrylic acid copolymers towards
inhibiting deposition of the residues addressed herein is
significantly increased when it is used together with multivalent
metallic species such as calcium ions. From In examples 2-8 it is
clear that increasing the calcium increases the detackification
values. Increased detackification occurs upon increasing the
calcium concentration to about 50 ppm, after which the performance
levels are seen to level off Examples 11-18 evidence the same
performance qualities of the compositions, except at lower
temperature, thus evidencing the temperature-independence of the
general effect discovered. In addition, there seems to be an
optimum styrene content as evidenced by examples 20-23, which is
about 15% to about 40%. Of the styrene methacrylic copolymers
tested, STYMAA 1 and STYMMA 3 exhibited the best performance as
reflected by their ultra-low peel force. These results are in
agreement with those obtained from surface tension and contact
angle measurements. Thus these are preferred polymer compositions
according to the invention. Unless noted otherwise, all molecular
weights specified in this specification and the claims appended
hereto in are on a weight-average molecular weight basis.
[0040] A composition according to one form of the present invention
does not contain any pitch, stickies, or other materials known to
those skilled in the papermaking art to cause fouling on
papermaking equipment. This is because a composition according to
the present invention is intended to be added to a papermill
furnish or other fiber refining operation in which stickies, pitch,
and other fouling substances known to those in fiber processing
arts are present, in order to lessen their detrimental effect on
the associated equipment.
[0041] Consideration must be given to the fact that although this
invention has been described and disclosed in relation to certain
preferred embodiments, obvious equivalent modifications and
alterations thereof will become apparent to one of ordinary skill
in this art upon reading and understanding this specification and
the claims appended hereto. Accordingly, the presently disclosed
invention is intended to cover all such modifications and
alterations, and is limited only by the scope of the claims which
follow.
* * * * *