U.S. patent application number 11/710765 was filed with the patent office on 2007-07-05 for nonviscous aqueous dispersion compositions of water-swellable layered silicates and the method of producing the same.
This patent application is currently assigned to AMCOL International Corporation. Invention is credited to Jerald W. JR. Darlington, Jennifer Gould, Ilona Lin, Ashoke K. SenGupta.
Application Number | 20070151931 11/710765 |
Document ID | / |
Family ID | 32313061 |
Filed Date | 2007-07-05 |
United States Patent
Application |
20070151931 |
Kind Code |
A1 |
SenGupta; Ashoke K. ; et
al. |
July 5, 2007 |
Nonviscous aqueous dispersion compositions of water-swellable
layered silicates and the method of producing the same
Abstract
Concentrated suspensions of smectite clays are obtained as
either relatively "thin" or highly shear-thinning slurries that are
easy to pump, by adding one or more of certain cationic polymers
whose weight average molecular weight, Mw, is 50,000 or higher. It
was found during the course of the invention that a cationic
polymer with an Mw of 10,000 did not work, while the same polymer
with a bimodal Mw of 50,000 and 30,000 worked satisfactorily. To
achieve the full advantage of the present invention, the cationic
polymer preferably has 1 to 10 milliequivalents of cationic charge
per gram of the polymer, and more preferably 5 to 10
milliequivalents of cationic charge per gram of the polymer, and
most preferably 6 to 8 milliequivalents of cationic charge per gram
of the polymer.
Inventors: |
SenGupta; Ashoke K.;
(Barrington, IL) ; Darlington; Jerald W. JR.;
(Marengo, IL) ; Gould; Jennifer; (Lake in the
Hills, IL) ; Lin; Ilona; (Wauconda, IL) |
Correspondence
Address: |
MARSHALL, GERSTEIN & BORUN LLP
233 S. WACKER DRIVE, SUITE 6300
SEARS TOWER
CHICAGO
IL
60606
US
|
Assignee: |
AMCOL International
Corporation
Arlington Heights
IL
|
Family ID: |
32313061 |
Appl. No.: |
11/710765 |
Filed: |
February 26, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10706752 |
Nov 12, 2003 |
|
|
|
11710765 |
Feb 26, 2007 |
|
|
|
60425862 |
Nov 13, 2002 |
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Current U.S.
Class: |
210/702 ;
524/445 |
Current CPC
Class: |
A61K 2800/5426 20130101;
C02F 1/5236 20130101; C08K 3/34 20130101; A61K 8/817 20130101; C02F
1/56 20130101; C08K 3/346 20130101; A61K 8/26 20130101; C02F
2103/002 20130101; A61Q 5/06 20130101; C08K 7/00 20130101 |
Class at
Publication: |
210/702 ;
524/445 |
International
Class: |
C02F 1/52 20060101
C02F001/52; C08K 9/04 20060101 C08K009/04 |
Claims
1. An aqueous suspension comprising a sodium smectite clay, and at
least one water-soluble, cationic polymer with a weight average
molecular weight of at least 50,000, wherein the amount of sodium
smectite clay exceeds 20 weight percent based on the total weight
of the aqueous suspension, and wherein the aqueous suspension has a
Brookfield RV viscosity, at 10 rpm, less than 6,000 cps, when
measured at 38% sodium smectite clay, based on the total weight of
clay and water.
2. The suspension of claim 1 wherein the layered silicate is
selected from the group consisting of smectite clays, lithium
magnesium silicate (laponite), and a mixture thereof.
3. (canceled)
4. The suspension of claim 1 wherein the amount of sodium smectite
clay is from greater than 20 weight percent to 50 weight percent
based on the total weight of the suspension.
5. The suspension of claim 4 wherein the amount of sodium smectite
clay is from 25 weight percent to 50 weight percent based on the
total weight of the suspension.
6. The suspension of claim 5 wherein the amount of sodium smectite
clay is from 25 weight percent to 45 weight percent based on the
total weight of the suspension.
7. The suspension of claim 1 wherein the weight ratio of sodium
smectite clay to the cationic polymer is 2:1 to 1000:1.
8. The suspension of claim 7 wherein the amount of cationic polymer
in the suspension is in the range of 0.1% to 50% based on the dry
weight of sodium smectite clay.
9. The suspension of claim 8 wherein the amount of cationic polymer
in the suspension is in the range of 8% to 30% based on the dry
weight of sodium smectite clay.
10. The suspension of claim 9 wherein the amount of cationic
polymer in the suspension is in the range of 10% to 25% based on
the dry weight of sodium smectite clay.
11. The suspension of claim 1 wherein the cationic polymer has 1 to
10 milliequivalents of cationic charge per gram of the polymer.
12. The suspension of claim 11 wherein the cationic polymer has 5
to 10 milliequivalents of cationic charge per gram of the
polymer.
13. The suspension of claim 12 wherein the cationic polymer has 6
to 8 milliequivalents of cationic charge per gram of the
polymer.
14. The suspension of claim 1 wherein the suspension contains a
mixture of a lower molecular weight cationic polymer and a higher
molecular weight cationic polymer, at least one of which has a
weight average molecular weight of at least 50,000.
15. The suspension of claim 14, wherein the weight ratio of the
lower molecular weight cationic polymer to the higher molecular
weight cationic polymer is in the range of 10:1 to 1:10.
16. The suspension of claim 15, wherein the weight ratio of the
lower molecular weight cationic polymer to the higher molecular
weight cationic polymer is in the range of 7:1 to 1:7.
17. The suspension of claim 16, wherein the weight ratio of the
lower molecular weight cationic polymer to the higher molecular
weight cationic polymer is in the range of 1:1 to 1:7.
18. A method of clarifying a wastewater containing suspended matter
comprising adding to said wastewater an effective amount of the
aqueous suspension of claim 1 to flocculate or coagulate the
suspended matter.
19. The method of claim 18, comprising adding to said wastewater
the sodium smectite clay and cationic polymer at a combined dry
weight of 1 ppm to 10,000 ppm, based on the weight of the
wastewater treated.
20. The method of claim 19, comprising adding to said wastewater
the sodium smectite clay and cationic polymer at a combined dry
weight of 10 ppm to 1,000 ppm, based on the weight of the
wastewater treated.
21. The method of claim 20, comprising adding to said wastewater
the sodium smectite clay and cationic polymer at a combined dry
weight of 10 ppm to 500 ppm, based on the weight of the wastewater
treated.
22.-26. (canceled)
27. A method of softening a fabric comprising contacting said
fabric with an effective amount of the aqueous suspension of claim
1.
28. The method of claim 27, wherein the aqueous suspension is
diluted with water during fabric softening such that the
concentration of sodium smectite clay and cationic polymer in said
water is in the range of 0.001% to 5% by weight, based on the total
weight of water.
29. The method of claim 28, wherein the aqueous suspension is
diluted with water such that the concentration of sodium smectite
clay and cationic polymer in said water is in the range of 0.005%
to 3.0% by weight, based on the total weight of water.
30. The method of claim 29, wherein the aqueous suspension is
diluted with water such that the concentration of sodium smectite
clay and cationic polymer in said water is in the range of 0.1% to
2.5% by weight, based on the total weight of water.
31. The method of claim 30, wherein the aqueous suspension is
diluted with water such that the concentration of sodium smectite
clay and cationic polymer in said water is in the range of 0.3% to
1.0% by weight, based on the total weight of water.
32. A method of reducing the viscosity of an aqueous suspension of
a having greater than 20 weight percent sodium smectite clay
comprising shearing said suspension with a cationic polymer having
a weight average molecular weight of at least 50,000, such that the
aqueos suspension has a Brookfield RV viscosity, at 10 .mu.m, less
than 6,000 cps, when measured at 38% sodium smectite clay, based on
the total weight of clay and water.
Description
SUMMARY OF THE INVENTION
[0001] This application is a continuation of U.S. patent
application Ser. No. 10/706,752, filed Nov. 12, 2003, which is
based on U.S. Provisional Patent Application 60/425,862, filed Nov.
12, 2002.
[0002] The present invention relates to concentrated, aqueous
dispersion or aqueous slurry compositions of water-swellable
layered silicates such as the smectite clays, which either have
unusually low viscosities or have high shear-thinning properties,
as well as the ability to coagulate/flocculate suspended materials
in water, and a method of producing the compositions. While the
weight content of the suspended clay particles in these slurry
compositions can be as high as 40-50%, the dispersions remain
sufficiently thin or shear-thinning to allow pumping of the slurry.
Ordinarily, even at relatively low concentrations (for example
5-10%), smectite clays can bring about significant thickening in
aqueous suspensions, often turning the suspensions into gels.
[0003] A key object of the present invention is to produce such
dispersions of smectite clays, which are amenable to pumping even
when the clay content is relatively high, in a manner that renders
the dispersion compositions especially suited for
coagulating/flocculating suspended matter in wastewater or other
water streams. This is achieved by adding one or more cationic
polymers with a weight average molecular weight of at least 50,000
Daltons to aqueous clay suspensions, at concentrations sufficient
for the cationic polymer(s) to function as a thinning agent for the
suspended clay particles.
[0004] Thickening or gelation of aqueous suspensions by smectite
clays is a manifestation of clay particles forming a network
structure due to interparticle associations, that spans through the
entire suspension volume, entrapping the suspension medium. A
thinning agent acts to minimize such particle-to-particle links by
providing for interparticle repulsion upon adsorption on the
particle surface. The use of a cationic polymer as a thinning agent
leaves the surface of the clay particles cationic such that these
cationic particles can draw anionic particles into
coagulation/flocculation by bridging two or more of such particles
that generally constitute the suspended matter in water
streams.
BACKGROUND OF THE INVENTION
[0005] Layered silicate materials such as the smectite clays are a
class of inorganic particulate materials that occur as stacks of
individual, planar silicate layers referred to as platelets in the
clay literature. Examples of smectite clays include
montmorillonite, bentonite, bidelite, hectorite, saponite, and
stevensite. These clays are popular particulate gellants or
thickeners for aqueous compositions.
[0006] Smectite clays also find use as a flocculation aid in
wastewater treatment where the flocculant compositions used are
generally solid admixtures of clay and other treatment reagents.
These flocculant products, however, are excluded from those
wastewater treatment scenarios where the facility is not equipped
to handle any solid treatment reagent. Since smectite clay-water
slurries turn into gels once the clay content exceeds a level that
may be as low as in the range of 5-10% by weight, handling,
especially pumping, of clay suspensions with high clay content may
prove to be extremely difficult, if not impossible. Nevertheless,
in order for it to be viable, any liquid product of clay-based
flocculants should have clay content much exceeding the above
range. The present invention reveals a method for achieving such
desirable liquid products of smectite clay-based flocculants, and
the compositions thereof.
[0007] The face-surfaces of the platelets of smectite clays bear
anionic charges counterbalanced by exchangeable cations that remain
electrostatically attracted to the anionic charge of the clay
surface. The exchangeable cations are generally either sodium ions
or calcium ions. Smectite clay is referred to as sodium or calcium
clay, depending on the type of predominant counterions associated
with the face-surfaces of the clay platelets. While the anionic
charge on the platelet face-surfaces does not vary with pH, the
electrical charge on the edge-surfaces of these clays, although
anionic under alkaline pH, could be cationic under acidic pH.
[0008] Fundamentally, the formation of particulate gels is a
manifestation of suspended colloidal particles forming a network
structure that entraps and thus immobilizes the suspending medium.
Clay-based gels may form when individual platelets or stacks of a
few, e.g., 3-15, aggregated platelets (tactoids) engage in
interparticle associations with their neighboring platelets. These
particle-to-particle links result in a particulate structure
pervading through the entire suspension-volume. Such interparticle
associations are governed by the interplay between the attractive
and repulsive forces that generally act between particles suspended
in a liquid.
[0009] Clearly, the strength of particulate gels will depend on the
number of interparticle associations in a given volume of the gel,
implying that the greater the number-concentration of suspended
particles, the stronger is the gel. Also, a dominance of the
attractive interactions over the repulsive interactions, the
likelihood of which increases with decrease in interparticle
separation distance, is required for suspended particles to
associate with their neighbors. An increase in number-concentration
of particles will tend to reduce their separation distances, an
effect that could be especially dramatic for planar particles since
the separation distance between two adjacent platelets will vary
along their lengths when their faces do not align in parallel
configuration. Nonetheless, too strong an attraction between
adjacent clay platelets may draw them into strong face-to-face
association, minimizing the number-concentration of particles.
[0010] Considering the above, the key to making clay-based gels is
to ensure that there is sufficient interplatelet repulsion for the
clay platelets to exfoliate (delaminate) under shear, releasing a
large number of platelets as individual platelets or tactoids
having fewer stacked platelets, that would then be available to
form a particle network. On the other hand, in order to form a
voluminous network structure, the net interaction (the sum of
attractive and repulsive forces) between the delaminated platelets
must be such that they can remain "bound" (attracted) to their
neighboring platelets without being drawn into strong face-to-face
association. Accordingly, the gel-network may form if the
delaminated platelets, while being separated from the surrounding
platelets by as thick as possible an intervening layer of the
suspending medium, reside in a minimum of free energy of
interaction with the neighboring platelets. Albeit physically
separated from their neighbors, the individual platelets are no
longer free to move independently, being trapped in a free energy
minimum, in effect producing a particulate structure, and therefore
thickening or gelation. Yet another phenomenon that clay-based gels
may form in aqueous compositions, is where clay platelets coagulate
due to edge-to-face associations, forming the so-called
"card-house" structure described in clay literature.
[0011] The sodium smectite clays exfoliate to a much greater extent
than their calcium analogs. For this reason, the sodium smectite
clays produce a significantly higher level of thickening as
compared to the calcium smectite clays. Therefore, one way of
having concentrated clay suspensions with high fluidity is to use
calcium smectite clays. However, such dispersions, while possibly
meeting the requirement of low viscosity, would not present a high
number concentration of delaminated platelets, which may be
desirable for having good flocculating properties during wastewater
treatment.
[0012] The ability of clay platelets to bring about
coagulation/flocculation of suspended debris particles in
wastewater is related to a phenomenon that may be described as
heterocoagulation (coagulation between dissimilar materials)
between the clay platelets and the debris particles. Such
heterocoagulation would occur when the physicochemical conditions
of the wastewater are such that the interaction between the debris
particles and the clay platelets is attractive, even though the
interaction between the debris particles is repulsive, preventing
these particles from coagulating. Another way to describe such a
heterocoagulation process is to use the analogy of bridging
flocculation by polymeric flocculants, as described in colloid
literature: like polymeric flocculants, the clay platelets draw the
suspended debris particles into flocculation by sticking to and
thus bridging two or more debris particles simultaneously.
[0013] It may be expected that the aforementioned debris-clay
coagulation process will be favored if the number concentration of
clay platelets is high (i.e., if the clay platelets are highly
delaminated or exfoliated, an effect that also promotes thickening
induced by clay platelets) and/or if a strong clay platelet-debris
particle attraction is brought into play. Accordingly, conflicting
demands are faced in obtaining concentrated, non-viscous
clay-suspensions where the clay platelets are sufficiently
delaminated in order to have good flocculating power. Nevertheless,
even when a large number of clay platelets have been released due
to exfoliation, the platelets may be prevented from engaging into
any association with the neighboring platelets if the interparticle
repulsive forces greatly dominate over the attractive forces.
Therefore, the key to attaining concentrated, but non-viscous
clay-suspensions, without necessarily sacrificing good exfoliation
of clay platelets, is to ensure that strong repulsive forces act
between the platelets, superseding any attractive interplatelet
forces that tend to bring about associations between the platelets.
Most surfaces tend to acquire an anionic charge when wetted with an
electrolyte or water. Also, the surface active agents (emulsifiers
and dispersing agents) that are more commonly used in industrial
applications are anionic, resulting in suspended particles in most
wastewater streams that are generally anionic. So in the context of
clay-based flocculants, it has been found that a way to increase
the clay platelet-debris attraction is to render the surface of the
clay platelets cationic through the adsorption of cationic
species.
[0014] As described in colloid literature, ionic polymers or
polyelectrolytes may provide for electrical and steric repulsion
forces between suspended particles, if, upon adsorption on the
particle surface, i) the adsorbed polymer chains render the
particle surface electrically charged, ii) the adsorbed polymer
chains occupy more than 50% of the particle surface area, and iii)
the polymer segments dangle out off the particle surface into the
surrounding dispersion medium, forming loops and tails. Once
brought into play, these repulsion forces act to minimize
interparticle associations, resulting in thinning of the
suspension. The adsorption of cationic polyelectrolytes on the
surface of clay platelets could potentially increase the attractive
interaction between the clay platelets and the anionic debris
particles, which in turn could enhance the flocculating ability of
clay.
[0015] Although the prior art teaches the use of various types of
anionic polymer as thinning agents for smectite clay suspensions,
it does not disclose the effects of cationic polymers on the
rheological properties (for example, viscosity properties) of
concentrated clay suspensions (for example, suspensions having a
smectite clay content exceeding 20% by weight). Therefore, it is
not clear whether or not the addition of a cationic polymer to a
concentrated suspension of smectite clay would produce either a
"thin" or a highly shear-thinning suspension that shows a viscosity
significantly lower than what it would have been in the absence of
the polymer. It is only since the present invention that it has
been found that cationic polymers with a weight average molecular
weight falling within a certain range, when used even at relatively
low concentrations, would render a concentrated suspension of
smectite clays non-viscous, while the suspension shows considerable
flocculating ability.
[0016] Although a targeted application for the product of the
present invention is coagulation/flocculation of suspended matter
in water streams as, for example, in wastewater treatment, because
of the coagulating ability of the product, it may be used even as a
drainage aid in the papermaking process, wherein the product helps
in bringing about agglomeration of pulp fibers to facilitate the
drainage process.
[0017] Other potential uses of the product include, but are not
limited to, an additive in personal care and cosmetic formulations,
as well as a fabric softener. The cationic polymer-modified clays
would be substantive to (or adhere onto) the anionic surfaces of
the hair or the skin, such that these clays can help deliver some
useful hair care or skin care properties when used as an additive
in personal care or cosmetic products. For example, the deposition
of cationic clay platelets on the anionic surface of the hair
shafts is expected to be substantive to hair shafts to enhance hair
styling. Accordingly, the use of cationic polymer-modified clays in
hair care products should add to the hair styling properties of
these products. The prior art discloses the use of smectite clays
as a fabric softener. Furthermore, the most commonly used fabric
softeners are cationic surfactants. As for the molecular structure,
surfactant molecules contain a hydrophilic part and a hydrophobic
part, with the two parts of the molecule segregated from one
another. The cationic surfactants used as fabric softeners impart
softness by adsorbing onto the (negatively charged) fabrics with
their hydrophilic part, consisting of the cationic functional
group, attached onto the fabric surface, while their hydrophobic
part projects outwardly from the surface. Such adsorption of the
cationic surfactants minimizes interfacial tension between the
fabric surface and the surrounding air mass and minimizes the
adhesion of water to the fabric surface. This reduces the shrinkage
(reduction of substrate surface area) and resulting hard "feel"
that accompanies the removal of water from the substrate. In
accordance with the present invention, the cationic modification of
the smectite clay surface by the surface treatment of the clay with
one or more cationic species, e.g., polymers, that contain one or
more hydrophobic groups, render the clay platelets better equipped
to serve as a fabric softener.
SUMMARY OF THE INVENTION
[0018] The objects of the present invention are as follows: [0019]
Produce concentrated suspensions of layered silicate materials,
that are amenable to pumping, and show good
coagulating/flocculating abilities by surface treating the layered
silicate material with cationic polymers. [0020] Provide a method
for surface-treating particles of layered silicate materials, that
would result in thinning of concentrated suspensions of these
particulate materials, while rendering the particles better
equipped to function as a coagulant/flocculant [0021] Produce a
surface-modified clay wherein the clay surface is rendered cationic
due to the surface-treatment of the clay with one or more cationic
polymer(s), in order that such cationically-modified clays are
useful in formulating hair and skin care products as well as a
fabric softener
[0022] Preferably, the weight content of the layered silicate
material in the suspension is more than 25%, and the weight ratio
of the silicate mineral and the thinning reagent is 4:1 to 10:1.
Since one of the targeted application areas, i.e., wastewater
treatment, for the product of the present invention, is highly
cost-sensitive, it is important that the dosage level of the
thinning agent is held relatively low.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] The preferred layered silicate materials are phyllosilicates
of the 2:1 type with an anionic charge on the face surface,
counterbalanced by sodium counterions. More preferably, the layered
silicate materials are smectite clays such as montmorillonite,
bentonite, bidelite, hectorite, saponite, and stevensite.
[0024] According to the present invention, concentrated suspensions
of smectite clays are obtained as either relatively "thin" or
highly shear-thinning slurries that are easy to pump, by adding one
or more of certain cationic polymers whose weight average molecular
weight, Mw, is 50,000 or higher. It was found during the course of
the invention that a cationic polymer with an Mw of 10,000 did not
work, while the same polymer with a bimodal Mw of 50,000 and 30,000
worked satisfactorily. To achieve the full advantage of the present
invention, the cationic polymer preferably has 1 to 10
milliequivalents of cationic charge per gram of the polymer, and
more preferably 5 to 10 milliequivalents of cationic charge per
gram of the polymer, and most preferably 6 to 8 milliequivalents of
cationic charge per gram of the polymer.
[0025] The word "thin" above refers to such slurry consistency or
viscosity as exemplified by the Brookfield RV viscosity (at 10 rpm)
of a suspension containing 38% of a sodium smectite clay (based on
the total weight of clay and water, the dispersion medium), and
under strong agitation by, for example, a shaft-mounted agitator,
is less than 6,000 cps, more preferably less than 1,000 cps, and
most preferably less than 500 cps. The clay content of the
concentrated suspensions of the present invention, expressed as a
percentage of the total weight of clay and water (dispersion
medium), is in the range of 1-50%, more preferably in the range of
5-45%, and most preferably in the range of 25-45%. The dosage of
the cationic polymer based on the dry weight of clay is in the
range of 0.1-50%, more preferably in the range of 8-30%, and most
preferably in the range of 10-25%.
[0026] According to one embodiment of the present invention, the
smectite clay is surface-treated with a mixture of low and high
molecular weight cationic polymers, wherein the weight average
molecular weight of the high molecular weight cationic polymer is
at least 50,000. When such mixtures of cationic polymers are used,
the weight ratio of the low molecular weight polymer to the high
molecular weight polymer is in the range of 10:1 to 1:10, more
preferably in the range of 7:1 to 1:7, and most preferably in the
range of 1:1 to 1:7.
[0027] An important embodiment of the present invention is that the
concentrated suspension of cationic polymer-modified layered
silicate materials shows coagulating/flocculating abilities either
by itself or in conjunction with one or more additional anionic or
cationic polymers that are commonly used as a flocculant. By the
phrase "coagulating/flocculating ability" is meant the ability to
significantly increase the clarity or reduce the turbidity of a
water stream that contains suspended matter, by inducing
aggregation of most or all of the suspended matter, forming
aggregated particles or flocs, for easy separation from the
water.
[0028] The most preferred cationic polymers that can be used in
producing thin, concentrated suspensions of layered silicate
materials include but not limited to poly (diallyldimethylammonium
chloride) referred to herein as poly(DADMAC), polyquaternary amine
polymers prepared from epichlorohydrin and dimethylamine referred
to herein as EPI/DMA, and their copolymers with non-ionic,
water-soluble polymers. Cationic polymers having weight average
molecular weights of 50,000 or higher, derived from natural
polymers such as tannin, starch, proteins, guar, gum, lignin,
lignosulfonate, and humate can also be used. Polyalkyl amines or
polyaryl amines having a weight average molecular weight of at
least 50,000 can be used as well. For use in personal care and
cosmetic product formulations, any cationic polymer with a weight
average molecular weight of at least 50,000, including various
cationic copolymers that are used in hair and/or skin care products
may be useful. Film forming cationic polymers (for example,
chitosan polymers or copolymers; cationic polymers or copolymers
containing polyvinyl pyrrolidone; polyacrylate; and
polyalkylmethacrylate); cationic polymers or copolymers containing
hydroxyl, carboxyl, carbonyl, phenolic, and/or ether groups; as
well as cationic polymers or copolymers that contain a strong
hydrophobic moiety such as an alkyl chain of C8 or higher, and one
or more aromatic groups may be used when the product of the present
invention is used in personal care and cosmetic formulations.
[0029] In accordance with another embodiment of the present
invention, the dispersions of cationic polymer-modified clay
further contain one or more coagulation/flocculation aids such as a
salt of monovalent, and preferably multivalent, cations such as
aluminum, iron, and calcium.
[0030] For wastewater treatment, the dosage of the product of the
present invention, based on the sum of the weights of the dry clay
and the dry cationic polymer, could be in the range of 1 ppm-10,000
ppm, more preferably in the range of 10 ppm-1000 ppm, and most
preferably in the range of 10 ppm-500 ppm. For the fabric softening
application, the product dosage, based on the sum of the weights of
the dry clay and the dry cationic polymer, could be in the range of
0.005%-30% of the total weight of the fabric softener formulation,
more preferably in the range of 1%-20%, and most preferably in the
range of 1%-10% of the formulation. A detergent product that may
contain the product of the present invention as a fabric softener
component of the formulation may be eventually used in a diluted
form, for example, as encountered in a wash cycle of a commercial
washer. For hair and skin product formulations, the dosage of the
product of the present invention, based on the sum of the weights
of the dry clay and the dry cationic polymer, could be in the range
of 0.005%-10% of the hair or skin care product formulation, more
preferably 0.005%-5% of the formulation, and most preferably 1%-5%
of the formulation. Since hair and/or skin care products generally
contain a vehicle or a solvent, the solvent composition should
contain at least 20% by weight of water, in order to get the full
benefit of the present invention.
[0031] In the present invention, the thin, concentrated suspensions
of layered silicate materials are produced by adding a single
layered silicate material, or a mixture of layered silicate
materials to an aqueous solution of one or more of the
aforementioned types of cationic polymers, and then shearing the
resulting suspension using a shearing device such as a
shaft-mounted shearing agitator, a rotor-stator mixture, a
homogenizer, a media mill, or a colloid mill for a period of time
to at least partially exfoliate the layered silicate
material(s).
[0032] In order to illustrate the present invention clearly, the
following examples and data are presented. However, they should not
be construed as limiting the scope of the invention to their
details.
EXAMPLE 1
[0033] This example shows the thinning ability of poly(DADMAC)
(ZETAG 7131, weight average molecular weight, Mw=100,000, obtained
from Ciba Specialty Chemicals) in concentrated suspensions of
smectite clay. The procedure followed in carrying out the
slurry-viscosity tests for evaluating the cationic polymer is as
follows: 76 grams of a sodium smectite clay (ACCOFLOC obtained from
CETCO/AMCOL International and POLARGEL NF obtained from ACC/Amcol
International) was slowly added to an aqueous solution of the
cationic polymer, and sheared in a multi-speed Waring blender,
while the blender was operated at speed 1. Immediately after the
entire amount of clay was added, the resulting slurry was
homogenized at speed 7 (22,000 rpm) of the blender for 5 minutes.
The suspension thus produced was transferred to a plastic container
and the viscosity was measured in a Brookfield RV viscometer. The
slurry-viscosity was measured after 20-25 minutes from the time of
completion of mixing, at shear rates corresponding to 10, 20, 50,
and 100 rpm of spindle speed in a Brookfield RV viscometer. After
completion of viscosity measurements, the lid of the slurry
container was replaced and the suspension was shaken vigorously by
hand for a brief period of time, after which the slurry viscosity
was measured again at 10 rpm. The results of the slurry viscosity
tests are shown in Table I. TABLE-US-00001 TABLE I Viscosity Time
Since after Completion Brookfield Manual Cationic Tap of Mixing,
Viscosity, Shaking, Test # Clay Polymer, g Water, g minutes Rpm cps
cps 1 ACCOFLOC 27.14 106.46 20 10 350 75 ZETAG 7131 20 250 (35%
solids) 50 178 100 159 2 ACCOFLOC 32.57 102.93 20 10 120 60 ZETAG
7131 20 115 50 108 100 110 3 POLARGEL 21.71 109.99 20 10 12,000
2,000 NF ZETAG 7131 20 6,750 50 3,000 100 1,775 4 POLARGEL 27.14
106.46 20 10 4,200 475 NF ZETAG 7131 20 2,350 50 1,080 100 660 5
POLARGEL 32.73 102.83 20 10 4,400 475 NF ZETAG 7131 20 2,550 50
1,300 100 800
[0034] It should be noted that the slurries from tests 3 through 5
thickened up to the consistency of a gel after about 16 days of
standing. However, upon shaking the slurry containers vigorously by
hand for a brief period of time, the suspensions from tests 4 and 5
showed high shear thinning, with 890 cps and 750 cps, respectively,
being their Brookfield viscosities at 10 rpm.
EXAMPLE 2
[0035] This example shows the efficacy of EPI/DMA (SUPERFLOC C-573
Flocculant, bimodal weight average molecular weight, Mw=50,000 and
30,000, from Cytec Industries, and ZETAG 7191, weight average
molecular weight, Mw=50,000, from Ciba Specialty Chemicals) as a
thinning agent in concentrated sodium smectite clay suspensions,
based on slurry viscosity tests. The procedure followed in carrying
out the slurry-viscosity tests is the same as that described in
EXAMPLE 1. The results of the slurry viscosity tests are shown in
Table II. TABLE-US-00002 TABLE II Time Since Viscosity Completion
Brookfield after Cationic Tap of Mixing, Viscosity, Shaking, Test #
Clay Polymer, g Water, g minutes Rpm cps cps 1 ACCOFLOC 19 114.6 23
10 3,000 Viscous C-573 (50% 20 1,375 solids) 50 900 100 580 2
ACCOFLOC 22.8 112.7 20 10 700 40 C-573 20 500 50 240 100 190 3
ACCOFLOC 26.6 110.8 20 10 260 12 C-573 20 165 50 95 100 69 4
ACCOFLOC 22.8 112.7 30 10 3,700 40 ZETAG 20 1,300 after about 6
7191 50 480 hours from 100 390 the time of mixing
EXAMPLE 3
[0036] This example shows that cationic reagents having a
relatively low weight average molecular weigh would not work well
as thinning agents for concentrated suspensions of sodium smectite
clay. The cationic reagents evaluated include SUPERRFLOC C-572
Flocculant (Mw=10,000, from Cytec Industries), and AGEFLEX (monomer
for the DADMAC polymer from Ciba Speciality Chemicals). Slurry
viscosity tests were carried out the same as in the previous
examples. TABLE-US-00003 TABLE III Time Since Viscosity Completion
Brookfield after Cationic Tap of Mixing, Viscosity, Shaking, Test #
Clay Polymer, g Water, g minutes Rpm cps cps 1 ACCOFLOC 22.8 112.7
30 10 10,800 C-572 (50% 20 5,350 solids) 50 2,760 100 1,320 2
ACCOFLOC 30.4 108.9 35 10 4,300 5,250 C-572 20 2,875 50 1,360 100
750 3 ACCOFLOC 38 105.1 20 10 4,100 3,300 C-572 20 2,300 50 980 100
530 4 ACCOFLOC 27.14 115.96 20 10 4,200 2,700 Ageflex 20 2,400 (70%
solids) 50 1,860 100 1020
EXAMPLE 4
[0037] This example shows the slurry thinning ability of mixtures
of cationic polymers, ZETAG 7131, with Mw=100,000, and ZETAG 7122,
with Mw=425,000, in a concentrated suspension of sodium bentonite
clay. Similar slurry-viscosity tests as in the previous examples
were carried out. TABLE-US-00004 TABLE IV Time Since Viscosity
Completion Brookfield after Cationic Tap of Mixing, Viscosity,
Shaking, Test # Clay Polymer, g Water, g minutes Rpm cps cps 1
ACCOFLOC 32.57 102.93 20 10 120 60 ZETAG 7131, 20 115 15% polymer
50 108 on clay 100 110 2 ACCOFLOC 57 78.5 20 10 19,750 17,500 Zetag
7122, 20 14,375 15% polymer 50 9,460 on clay 100 6,940 3 ACCOFLOC
16.29 113.41 20 10 Highly ZETAG 20 viscous 7131, 7.5% 50 polymer on
100 clay 4 ACCOFLOC 28.5 101.2 20 10 Highly ZETAG 7122, 20 viscous
7.5% polymer 50 on clay 100 5 ACCOFLOC 28.5 90.61 20 10 1,500 700
ZETAG 7122 + 16.29 20 1,300 ZETAG 7131, 50 1,100 15% polymer 100
940 on clay 6 ACCOFLOC 76 ZETAG 58.97 20 10 4,250 7122 + 6.51 20
3,700 ZETAG 7131, 50 3,120 23% polymer 100 2,760 on clay
EXAMPLE 5
[0038] This example shows the coagulating/flocculating ability of a
concentrated suspension of sodium smectite clay, wherein
poly(DADMAC) is used as the thinning agent for the slurry. The clay
suspension is identical in composition to the clay suspension in
Test 1 of EXAMPLE 1. Flocculation tests were carried out by adding
a given weight of the clay suspension to 100 grams of an industrial
wastewater sample having poor clarity or high turbidity. In some
cases, a measured amount of a 15% alum solution was added to the
wastewater sample along with the clay suspension. After mixing
(using a magnetic stirrer) the clay suspension and/or the alum
solution with the wastewater for 1 minute, an aliquot of a dilute
solution (0.1%-1% by weight) of an anionic flocculant (sodium
polyacrylate) marketed under the trade-name of F730A by CETCO was
added to the wastewater, and mixing was continued for an additional
1.25 minutes during which time the suspended materials contained in
the wastewater separated out as large flocs. The treated wastewater
thus obtained was filtered, and the filtrate was taken for %
Transmittance (% T) measurement (at 620 nm wavelength) in a Hach
Spectrophotometer calibrated with deionized water for 100% T. A
high value of % T indicates a high level of clarification or a low
level of turbidity. TABLE-US-00005 TABLE V Wastewater Clay 15% Alum
Anionic Test # sample ID Suspension, g solution, g polymer, g pH %
T Comments 1 Thomas Betts 0 0.3 6, No 0.1% clarification solution
of F730A 2 Same as 0.25 0.3 6, 7.39 94 above 0.1% solution of F730A
3 Same as 0.3 0.35 6, 7.18 95 above 0.1% solution of F730A 4 Same
as 0.35 0.3 6, 7.86 97 above 0.1% solution of F730A 5 Muellor 0.3
0.3 0.28, 8.99 97 Vibratory 1% solution of F730A 6 Muellor 0.3 0
0.3 9.09 98 Vibratory 1% solution of F730A
EXAMPLE 6
[0039] This example shows the coagulating/flocculating ability of
sodium bentonite dispersions containing mixtures of cationic
polymers, ZETAG 7131, with Mw=100,000, and ZETAG 7122, with
Mw=425,000. The compositions of the dispersions tested are given
below.
[0040] Slurry # 1
[0041] ACCOFLOC clay=100 g
[0042] ZETAG 7131=22.86 g
[0043] ZETAG 7122=22.5 g
[0044] Tap water=91.14 g
[0045] Slurry # 2
[0046] ACCOFLOC clay=100 g
[0047] ZETAG 7131=8.57 g
[0048] ZETAG 7122=100 g
[0049] Tap water=47 g
[0050] The dispersions were tested for clarifying ability in a
sample of a laundry wastewater. The results of these flocculation
tests are shown in Table VI. TABLE-US-00006 TABLE VI Clay
Suspension, Anionic Test # Slurry # ppm Polymer, ppm % T 1 1 780 10
97 2 2 300 Approximately 94.5 10-30
* * * * *