A method is disclosed for the preparation of concentrated, homogeneous, free flowing clay-polymer powders which upon addition to an aqueous solution may be inverted so as to produce a beneficiated clay.

INTRODUCTION 
This invention relates to a new method and composition concerning 
homogeneous, concentrated, free flowing, clay-polymer powders. These 
powders are formed by adding a water-in-oil emulsion of a water soluble 
vinyl addition polymer directly to a powdered clay with agitation. The oil 
phase of the water-in-oil emulsion serves as a carrier causing the polymer 
particles to be homogeneously dispersed throughout the clay while 
maintaining the free flowing powder characteristics of the starting clay. 
This clay-powder depending on the concentration of the polymer within the 
clay can be either mixed with more clay or used as is so as to produce a 
beneficiated clay when added to an aqueous solution or fluid. The 
clay-polymer powders of our invention when added to water produce a 
beneficiated clay slurry due to the fact that the water-in-oil emulsion 
absorbed onto the clay powder inverts causing the polymer to solubilize, 
giving a rapid increase of viscosity to clay-polymer water mixture. 
The use of water-soluble acrylamide polymers as thickening agents, is 
well-known in the art. Commercially, these polymers are available in two 
forms: as a dilute liquid; and as a solid. 
The dilute liquid acrylamide polymer solutions, have two disadvantages. 
One, due to the viscosity of the high molecular weight material in water, 
they must be shipped as extremely dilute solutions, usually within the 
range of 0.5 to 3% polymer solids. Also, because they are so dilute, they 
cannot be used in applications where a more concentrated solution is 
desired. The solid acrylamide polymers are most often available 
commercially as powders or as finely divided solids. Due to their large 
particle size, a 100 mesh particle, being on the order of a 150 microns, 
it is difficult to disperse these polymers uniformily in clay solutions. 
In order to assure uniform distribution, they must be dissolved in water. 
Although the various polymers used are soluble in water, difficulty is 
often experienced in preparing aqueous polymer solutions because of slow 
dissolution, and because the solid polymer is not readily dispersible in 
water. Furthermore, dispersion of solid polymers in water is hindered by 
their tendency to clump or remain as agglomerates on contact with water. 
Lumps of solid polymer immediately form by the agglomerating. Although 
many of the lumps are eventually dissolved by continued agitation, it is 
frequently impractical to agitate the solution for a sufficiently long 
period of time to obtain complete dissolution. 
It would, therefore, be an advantage to the art if a compound could be 
found which would be easier to use and provide equivalent results. It is, 
therefore, the method of our invention to provide to the art a 
clay-polymer powder which when added to an aqueous fluid will produce a 
beneficiated clay in the aqueous medium. The method of this invention 
involves adding a water-in-oil emulsion of a finely divided acrylamide 
polymer to a clay powder with agitation so as to evenly disperse the 
emulsion in the clay. The water-in-oil emulsion is carried throughout the 
clay by the hydrophobic phase of the emulsion which is absorbed onto the 
surface of the clay resulting in a free flowing powder clay which contains 
polymer dispersed through the clay-polymer powder. This material may then 
be added to water whereupon the polymer inverts with the resulting 
benefication of the clay. 
OBJECTS 
It is, therefore, an object of our invention to provide a clay-polymer 
powder which is free flowing and which will release the polymer contained 
therein upon the addition of the clay powder to an aqueous fluid. 
Another object of this invention is to provide a method for thickening of 
clays by adding to the clay a water-in-oil emulsion of a finely divided 
acrylamide polymer followed by adding this free flowing mixture to an 
aqueous system thereby producing a beneficiated clay solution. 
A further object of this invention is to provide a method for producing a 
clay-polymer powder concentrate which can be used in a single addition to 
produce a beneficiated clay in an aqueous system. 
Other objects will appear hereinafter.

THE INVENTION 
This invention involves a method for producing a clay-polymer powder using 
a water-in-oil emulsion of a finely divided acrylamide polymer and the 
method for using this concentrate. 
The polymers most commonly used in the application of this invention are 
acrylamide polymers which include polyacrylamide and its water-soluble 
nonionic, cationic or anionic copolymeric derivatives such as, for 
instance, acrylic acid, methacrylic acid, itaconic acid, 
dimethylaminoethylmethacrylate, acrylonitrile and styrene. The copolymers 
contain from about 5 to 95% by weight of acrylamide. The molecular weights 
of such polymers exceed 500,000. 
A polymer also useful in the practice of this invention is hydrolyzed 
polyacrylamide which has from 1 to 50% of the original carboxamide groups 
hydrolyzed to carboxyl groups. 
The molecular weight of the polymers described above may vary over a wide 
range, e.g., 10,000 to 25 million. The preferred polymer has a molecular 
weight in excess of 1 million. 
In general, the polymer emulsions are stable yet at the same time contain 
relatively large amounts of polymer. The polymers dispersed in the 
emulsion are quite stable when the particle size of the polymer is within 
the range of 2 millimicrons up to about 5 microns. The preferred particle 
size is within the range of 5 millimicrons and 3 microns. 
It is extremely important for the purposes of our invention that particle 
size is kept as small as possible. This is due to the fact that the small 
particles are more easily blended in a uniform fashion than large 
particles. 
The stable water-in-oil emulsion comprises: 
1. An aqueous phase; 
2. A hydrophobic liquid; and 
3. A water-in-oil emulsifying agent. 
The polymer-containing emulsion of this invention is comprised of an 
aqueous phase ranging between 30 and 95% by weight of the emulsion. The 
aqueous phase is defined as the sum of the polymer or copolymer and the 
water present in the composition. The preferred range is between 70 and 
90% by weight of the emulsion. The most preferred range is between 70 and 
80% by weight of the emulsion. 
The present invention has a polymer concentration between 10 and 50% by 
weight of the emulsion. A preferred range is between 25 and 40% by weight 
of the emulsion. The most preferred range is between 25 and 35% by weight 
of the emulsion. 
The organic or oil phase of the emulsion is comprised of an inert 
hydrophobic liquid. The hydrophobic liquid usually comprises between 5 and 
70% by weight of the emulsion. The preferred range is between 5 and 30% by 
weight of the emulsion. The most preferred range is between 20 and 30% by 
weight of the emulsion. 
The oils used in preparing these emulsions may be selected from a large 
group of organic liquids which include liquid hydrocarbons and substituted 
liquid hydrocarbons. Preferred groups of organic liquids are hydrocarbon 
liquids which include blends of aromatic and aliphatic hydrocarbon 
compounds, which contain from 4 to 8 carbon atoms. Thus, such organic 
hydrocarbon liquids as benzene, xylene, toluene, mineral oils kerosenes, 
naphtha, and in certain instances, petroleums may be used. A particularly 
useful oil from the standpoint of its physical and chemical properties is 
the branch-chain isoparafinic solvent sold by Humble Oil and Refinery 
Company under the tradename "Isopar M". Typical specifications of this 
narrow-cut isoparaffinic solvent are set forth below in Table I. 
TABLE I 
______________________________________ 
Specification 
Properties 
Minimum Maximum Test Method 
______________________________________ 
Gravity, 
API at 60/60.degree. F 
48.0 51.0 ASTM D 287 
Color, Saybolt 
30 -- ASTM D 156 
Aniline Point, .degree. F 
185 -- ASTM D 611 
Sulfur, ppm 
-- 10 ASTM D 1266 
(Nephelometric mod.) 
Distillation, .degree. F 
IBP 400 410 
Dry Point -- 495 
Flash point, .degree. F 
(Pensky-Martens 
closed cup) 
160 -- ASTM D 93 
______________________________________ 
Any conventional water-in-oil emulsifying agent can be used such as 
sorbitan monostearate, sorbitan monooleate, and the so-called low HLB 
materials which are all documented in the literature and are summarized in 
the Atlas HLB Surfactant Selector. Although the mentioned emulsifiers are 
used in producing good water-in-oil emulsions, other surfactants may be 
used as long as they are capable of producing these emulsions. The 
water-in-oil emulsifying agent is usually present in amounts ranging 
between 0.1 and 21.0% by weight of the emulsion. The preferred range is 
between 1.0 and 5.0% by weight of the emulsion. The most preferred range 
is between 1.2 and 3.0% by weight of the emulsion. 
The polymers contemplated for use in this invention may be synthesized in 
emulsion form as described in Vanderhoff et al, U.S. Pat. No. 3,284,393 
which is hereby incorporated by reference. The polymerization technique 
set forth in Vanderhoff is generally followed in preparing polymeric 
latexes used in this invention. 
Also contemplated in the practice of this invention is the preparation of 
suitable water-in-oil emulsions of water-soluble polymers by the methods 
described in Anderson et al., U.S. Pat. Nos. 3,624,019 and 3,734,873, both 
of which are hereby incorporated by reference. 
THE METHOD 
Once the water-in-oil emulsion of a finely divided acrylamide polymer is 
prepared, it is added to a clay powder. The substance used as the clay may 
include clays, lignosulfonates, and minerals so long as hydrophobic phase 
is absorbed onto the material selected. Preferred clays for use in our 
invention include naturally occurring alumino-silicates, and include 
bentonite (montmorillonite type materials). Preferably the water-in-oil 
emulsion of the water soluble polymer is added to the clay at a weight 
percentage of from 0.1 to 40% based on the dry clay powder. Most 
preferably, from 10 to 30% by weight of the emulsion containing polymer is 
added to the dry clay powder. This mixture is then agitated to produce a 
homogeneous concentrated clay powder containing the polymer. At the levels 
described above, the clay totally absorbs the hydrophobic liquid phase 
from the water-in-oil emulsion of the finely divided vinyl addition 
polymer with the result being that a free flowing powder is achieved. This 
treated clay will still have the characteristics of a free flowing powder 
although with higher polymer additions than those described above the clay 
may not be able to absorb all of the hydrocarbon liquid in the hydrophobic 
phase with the result being that a "wet" looking product may be formed 
which is not free flowing. This is surprising in the fact that upon the 
addition of the polymer to the clay and due to the relative amounts of the 
aqueous phase and oil phase contained within our preferred water-in-oil 
emulsions it would be expected based on the teachings of Anderson et al., 
U.S. Pat. No. 3,624,019 that the clay would cause the polymer to invert 
creating a thickened mass rather than the free flowing powder obtained. 
After the clay-polymer powder is formed by the methods described above it 
may be used in a variety of applications. In order to successfully employ 
this mixture for the purposes which we have contemplated in our invention 
it will be necessary to add the clay-polymer powder to an aqueous system 
so as to provide a thickened clay solution having a polymer concentration 
of between 0.1 and 10% by weight of the aqueous solution. This is due to 
the fact that upon the addition of water, the polymer contained within the 
clay will invert so as to give the desired effect. 
Additionally, if more clay is desired then is achieved by the addition of 
our mixture to the aqueous solution clay can be added to the mixture of 
our invention itself, or in the alternative it may be added separately so 
as to cause the same end result. 
Oftentimes, in the practice of our invention we have found it necessary to 
add a hydrophillic surfactant to the aqueous fluid into which the 
clay-polymer powder is added. These surfactants are typically added in low 
concentrations, in amounts ranging from 0.01 to 50% by weight based on the 
polymer contained in the clay-polymer powder. Generally, the surfactant 
concentration when it is needed will be in the range of 1.0 to 10% by 
weight of the polymer contained within the clay. The preferred surfactants 
are hydrophilic and are further characterized as being water-soluble. Any 
hydrophilic-type surfactant such as ethoxylated nonyl phenols, ethoxylated 
nonyl phenol formaldehyde resins, dioctyl esters of sodium sulfosuccinate, 
and octyl phenol polyethoxyethanol can be used. Basically, any anionic, 
cationic or nonionic surfactant can be employed in this invention. The 
surfactants are fully disclosed in U.S. Pat. No. 3,624,019. The 
surfactants chosen, however, should be tried on a case-by-case basis due 
to variances in the water-in-oil emulsions, the clay, and the quality of 
the water into which the polymer is inverted. 
It is pointed out that it is oftentimes not necessary to use the 
hydrophillic surfactant and its usage will be dictated by the nature of 
the water-in-oil emulsion of the finely divided water soluble vinyl 
addition polymer so employed. Typically, in the applications which we have 
contemplated which include but are not limited to the formation of 
drilling muds, bases for earthen dams and clay "cements" the final 
material should employ polymer in the range of 0.1 to 10% of the total 
mixture with the clay comprising a substantial portion of the mixture. 
The amount of polymer, clay, and water used, will depend on the desired 
viscosity of the thickened clay. The use of more water will cause a 
decrease in viscosity. The use of greater amounts of polymer and greater 
amounts of clay will cause an increase in the viscosity. The following 
examples are offered to illustrate our invention. 
EXAMPLE 1 
______________________________________ 
Acrylamide emulsion recipe: 
______________________________________ 
ISO M 27.6 grams 
Sorbitan Monostearate 1.65 grams 
Water 40.20 grams 
Acrylamide 36.51 grams 
Sodium Hydroxide 2.29 grams 
2,2'azobis (isobutyronitrile) 
0.07 grams 
______________________________________ 
The sorbitan monostearate was dissolved in the ISO M and the resulting 
solution was poured into a 2 liter glass reactor filled with a stirrer, 
thermometer, and nitrogen purge. The monomer solution was prepared by 
dissolving the acrylamide in water. The pH of the monomer solution was 
adjusted to 8.5 with sodium hydroxide. The monomer solution was added to 
the organic phase with rapid agitation. The reactor was purged for 30 
minutes after which time the 2,2'azobis (isobutyronitrile) dissolved in 
acetone was added to the mixture. The emulsion was heated to 60.degree. C. 
with agitation. The reaction proceeded for 21/2 hours at which time it had 
reached completion. The resulting product was a stable emulsion. 
EXAMPLE 2 
______________________________________ 
Acrylamide-acrylic acid emulsion recipe: 
______________________________________ 
ISO M 28.10 grams 
Sorbitan Monostearate 1.85 grams 
Water 40.00 grams 
Acrylamide 33.90 grams 
Acrylic Acid 2.40 grams 
Sodium Hydroxide 2.30 grams 
2,2'azobis (isobutyronitrile) 
0.07 grams 
______________________________________ 
As in Example 1, the sorbitan monostearate was dissolved in the ISO M 
and the resulting solution was poured into a 2 liter glass reactor fitted 
with a stirrer, thermometer, and nitrogen purge. The monomer solution was 
prepared by dissolving the acrylamide and acrylic acid in water. The pH of 
the monomer solution was adjusted to 8.5 with sodium hydroxide. The 
monomer solution was added to the organic phase with rapid agitation. The 
reactor was purged for 30 minutes after which time the 2,2'azobis 
(isobutyronitrile) dissolved in acetone was added to the mixture. The 
emulsion was heated to 60.degree. C. with agitation. The reaction 
proceeded for 21/2 hours at which time it had reached completion. The 
resulting product was a stable emulsion. 
EXAMPLE 3 
______________________________________ 
Acrylamide-methacrylic acid emulsion recipe: 
______________________________________ 
ISO M 27.6 grams 
Sorbitan Monostearate 1.65 grams 
Water 40.20 grams 
Acrylamide 34.51 grams 
Methacrylic Acid 2.31 grams 
Sodium Hydroxide 2.29 grams 
2,2'azobis (isobutyronitrile) 
0.07 grams 
______________________________________ 
The sorbitan monostearate was dissolved in the ISO M and the resulting 
solution was poured into a 2 liter glass reactor fitted with a stirrer, 
thermometer, and nitrogen purge. The monomer solution was prepared by 
dissolving the acrylamide and methacrylic acid in water. The pH of the 
monomer solution was adjusted to 8.5 with sodium hydroxide. The monomer 
solution was added to the organic phase with rapid agitation. The reactor 
was purged for 30 minutes after which time the 2,2'azobis 
(isobutyronitrile) dissolved in acetone was added to the mixture. The 
emulsion was heated to 60.degree. C. with agitation. The reaction 
proceeded for 21/2 hours at which time it had reached completion. The 
resulting product was a stable emulsion. 
This invention is further illustrated by the following examples: 
EXAMPLE 4 
The water-in-oil emulsion of a finely divided acrylamide polymer of Example 
2, was added to Wyoming sodium bentonite at a 5% level (1.7% polymer 
solids). This clay-polymer powder was free flowing and resembled the 
sodium bentonite prior to addition of the water-in-oil emulsion. A 1% 
solution of the sodium bentonite-polymer powder, in water, containing 
0.17% nonylphenol which had been reacted with 10 moles of ethylene oxide, 
increased the viscosity from 50 to 100 cps as a result of this polymer 
addition. In practice, the sodium bentonite 5% polymer powder could be 
added to more sodium bentonite to achieve any intermediate viscosity. 
EXAMPLE 5 
The water-in-oil emulsion of a finely divided acrylamide polymer of Example 
1, was added to a Wyoming sodium bentonite at 5% level (1.68% polymer 
solids). The clay-polymer mixture so produced was a free flowing powder 
which could be transported and handled with relative ease. A 1% solution 
of this sodium bentonite polymer powder in water containing 0.15% 
nonylphenol which had been reacted with 10 moles of ethylene oxide, 
increased the viscosity from about 50 to about 100 cps as a result of this 
polymer addition. 
EXAMPLE 6 
To 400 parts by weight of a sodium bentonite was added 100 parts of a 
water-in-oil emulsion similar to that of Example 2 containing 
approximately 32.0% by weight of a acrylamide-sodium acrylate polymer. 
This was done with agitation and produced a clay-polymer powder which was 
free flowing and which had a slightly darker color than the dry clay 
itself. This clay-polymer powder contained 6.4% polymer (20% water-in-oil 
emulsion). A 2% solution (based on the weight of clay and polymer) of the 
treated clay was substantially more viscous than a 2% solution of the 
untreated material.