Polymer water-in-oil emulsions for the production of aqueous flocculants solutions are described in which the oil phase consists entirely or to a large degree of readily biodegradable compounds and these compounds are aliphatic dicarboxylic esters.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to organosol flocculants, which in an organic phase 
contain a very finely-distributed water-soluble polymer or a polymer 
dissolved in water which is composed primarily of acrylic and/or 
methacrylic monomers. 
2. Discussion of the Background 
Water-in-oil emulsions of, for instance, high molecular weight 
polyacrylamides or acrylamide copolymers have achieved particular 
importance in technical applications as liquid products which have a high 
percentage of solids while still retaining manageable viscosity. The 
reversability of the emulsion makes rapid production of aqueous solutions 
possible. They are also used, particularly as flocculants, in the refining 
of drinking water, for instance, or in purifying public and industrial 
effluents. 
There are well known procedures for manufacturing water-in-oil emulsions of 
compounds of high molecular weight by polymerization of water-dissolved, 
ethylene-unsaturated monomers in an oil-phase. Oils used in the production 
of polymer water-in-oil emulsions are liquid, non water-soluble, organic 
substances or mixtures of these substances. Thus, according to DE-A 1 081 
228, the oil phase may consist of any inert hydrophobic liquid which may 
include hydrocarbons and chlorinated hydrocarbons, for example, toluol, 
xylene, o-dichlorobenzene and propylene dichloride. 
According to DE-B 21 54 081, oils from a large group of organic liquids can 
be used, for instance, liquid hydrocarbons and substituted liquid 
hydrocarbons, including both aromatic and aliphatic compounds. Benzol, 
xylol, mineral oils, kerosine, naphthas and an isoparaffin-based oil, 
which is particularly well-suited, are named as examples of such liquid 
hydrocarbons. DE-A 22 26 143 also lists the above-mentioned organic 
substances to create the oil phase and DE-B 24 32 699 again indicates 
aromatic hydrocarbons and aliphatic hydrocarbons, such as paraffin oils 
and tetrachloroethylene, for a hydrophobic organic dispersion medium. 
DE-A 33 02 069 describes preparations which, among other things, are used 
as flocculants in which the oil phase may consist exclusively of the 
above-named aromatic and aliphatic hydrocarbons of natural plant or animal 
triglycerides, such as olive oil, peanut oil, cotton oil, coconut butter, 
beet oil, sunflower oil, and of fatty acid monoesters, primarily C.sub.1-4 
alkyl esters of C.sub.12-24 fatty acids such as oleic, palmitic, or 
hexadecylic acid. Mixtures of the above may be used if necessary. 
EP-A 45 720 and EP-A 80 976 describe water-in-oil emulsion polymers for 
cosmetic applications which require hydrophobic organic liquids such as 
aliphatic or aromatic hydrocarbons, animal or vegetable oils and the 
corresponding denatured oils as polymers in the oil phase. 
The use of organic flocculants as the base of water-in-oil emulsions with 
an oil phase of aliphatic and/or aromatic hydrocarbons, in waste-treatment 
installations, for example, carries with it the growing danger of 
contaminating the ground water and, consequently, the supply of drinking 
water because of the oil residue in the sludge that is deposited. 
The explanation for this lies in the fact that the treatment of sewage in a 
large city, for instance, causes several hundred kilograms of oil to be 
deposited with sewage sludge and that the decomposition of aliphatic and 
aromatic hydrocarbons by micro-organisms is only possible in the presence 
of oxygen and relatively slow even then. 
To remove the danger of poisoning the soil with such hard-to-degrade oils, 
the sludge is now burned. Another possibility would be to use polymer 
water-in-oil emulsions in which the oil phase consisted of substances 
which are more readily bio-degradable as, for instance, in the 
above-mentioned DE-A 33 02 069. However, burning the oil in the sludge or 
using natural plant or animal oils and C.sub.12-24 fatty-acid monoesters 
in the oil phase increases the cost of flocculants in the sewage-treatment 
installation considerably. Aside from the cost of natural oil, which is 
several times that of mineral oils, the natural products are less uniform 
and fluctuate in their composition which has an unfavorable effect on the 
quality of the organosol and its use as a flocculant. 
A need continues to exist for polymer water-in-oil emulsions in which the 
continuous oil phase consists of substances which are more readily 
bio-degradable than the previously used hydrocarbon oils and which, 
compared to natural oils and fats, can be produced more economically and 
which have more consistent properties. 
SUMMARY OF THE INVENTION 
Accordingly, one object of the present invention is to provide polymer 
water-in-oil emulsions or organosol flocculants which are more 
biodegradable that previously used hydrocarbon oils. 
A further object of the invention is to produce polymer water-in-oil 
emulsions or organosol flocculants which can be produced more economically 
and which have more consistent properties than natural oils and fats. 
Surprisingly, it was found that aliphatic dicarboxylic acid esters which 
can be biologically degraded, if necessary, after hydrolysis, are 
extremely suitable as the oil phase in the production of polymer 
water-in-oil emulsions and their utilization.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Dicarboxylic acid esters, and the dicarboxylic acids and monofunctional 
aliphatic alcohols needed for their production, are industrially 
synthesized on a large-scale. They are economical, of consistent quality 
and they are readily bio-degradable. 
The decomposition begins with the oxygen-containing center of the molecule. 
If necessary after prior hydrolytic separation of the ester group, by for 
instance enzyme catalyzation, the carbon chain of the dicarboxylic acid 
and also of the alcohol are decomposed by micro-organisms through beta 
oxidation. Adipic acid, for instance, is known to have a pronounced 
absence of toxicity, since it is rapidly oxidized within the organism. It 
is metabolized, according to well-known tests with C.sub.14 -labeled 
adipic acid, by beta oxidation within the organism just like normal fatty 
acids. 
Polymer water-in-oil emulsions, produced in accordance with the invention 
are environmentally compatible organosol flocculants and are suitable for 
water purification, for treatment of public and industrial effluents or as 
environmentily compatible liquidifiers for slurries of drilled minerals, 
for instance, when exploring or drilling for oil. 
In the process of the invention, water-soluble homo- and copolymers are 
produced in emulsions by polymerization of water dissolved 
ethylenically-unsaturated compounds in which the aqueous phase is 
dispersed in a continuous oil phase which contains considerable quantities 
of aliphatic dicarboxylic acid esters. The amount of dicarboxylic acid 
esters in the oil phase is at least 10% by weight, preferably at least 50% 
by weight, and may contain up to 100% by weight of this highly 
bio-degradable compound. In addition to the dicarboxylic acid esters which 
are suitable for the invention, the oil phase can also contain components 
which are known in the art to be used in the oil phase of polymer 
water-in-oil emulsions. Such components are, especially aliphatic 
hydrocarbons, animal or vegetable oils and fats and fatty acid monoesters. 
Examples of dicarboxylic acid components of the aliphatic dicarboxylic acid 
esters, in accordance with the invention are: oxalic acid, malonic acid, 
succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, 
azelaic acid and sebacic acid, which in the sequence used here, can be 
represented by the chemical formula 
EQU HOOC--(CH.sub.2).sub.x --COOH 
wherein x may be from 0 to 8. The C.sub.10 dicarboxylic acid mixture, 
available commercially under the trade of Isosebacinsaure Isosebacic acid, 
is a dicarboxylic acid ester which can be used in the process of the 
invention. Adipic and sebacic acids are preferred acids. 
The alcoholic components of the aliphatic dicarboxylic acid esters are 
monofunctional aliphatic alcohols with 1 to 20 atoms such as, for 
instance, methanol, ethanol, isopropanol, n-butanol isobutanol, 
2-ethylhexanol, 1-decanol, 1-undecanol, 1-dodecanol, 1-hexadecanol, 
1-octadecanol, isodecanol or isotridecanol. 2-Ethyl hexanol, which is 
produced by subsequent hydration of butyraldehyde produced by 
aldol-condensation during the oxo-synthesis process, is a preferred 
alcoholic component. 
Dicarboxylic acid esters with monofunctional alcohols are used industrially 
as softeners or lubricants. The esters used most frequently for this 
purpose are those from adipic, azelaic and sebacic acids particularly with 
oxo alcohols or Alfolen (registered Trademark) which, when industrially 
produced as mixtures, contain various alcohols. The industrial production 
of these alcohols is described, for instance, in Ullmann's "Encyclopedia 
of Industrial Chemistry", 4th ed vol 7, pp 203-223. It is , therefore, 
also within the scope of the invention to use lubricants, known as ester 
oils by the industry, which are obtained as esters from aliphatic 
dicarboxylic acids and monofunctional aliphatic alcohols as the oil phase 
of organosol flocculants and during their production. 
Examples of dicarboxylic acid esters, also known as ester oils and suitable 
for the invention, are bis-(2-ethylhexyl)sebacate, 
bis-(2-ethylhexyl)adipate and bis-(3, 5, 5-trimethylhexyl)adipate. Other 
examples of appropriate dicarboxylic acid esters are: succinic acid 
didodecyl ester, adipic acid dipropyl ester, and pimelic acid 
di-2-ethylhexyl ester. The dicarboxylic acid esters can also be used as 
mixtures wherein the dicarboxylic acid components and/or the alcohol 
components of the esters can be different. Industrial mixtures of such 
dicarboxylic acid esters are usually the previously mentioned ester oils. 
The continuous phase of the water-in-oil emulsion, which is the 
dicarboxylic acid ester oil phase, is present in quantities of 20 to 60% 
by weight in both the polymerization of the monomer emulsion and also in 
the dispersion to be used. 
According to the process of the invention, homo- and copolymers are 
produced which, as flocculants, increase the sedimentation rate of solids 
suspended in water. Monomers for the production of such polymers are 
compounds which are primarily soluble in water or in the aqueous monomer 
phase which are unsaturated and can be polymerized. Examples of such 
monomers are: acrylic acid; methacrylic acid; alkali salts of acrylic acid 
and methacrylic acid; the ammonium salts of these two acids; acrylamide; 
methacrylamide; N-substituted amides such as methyl methacrylamide, 
acrylamido- and methacrylamido alkyl sulfonic acids and their salts, such 
as 2-acrylamido-2-methyl propane sulfonic acid, known by its trade name of 
"AMPS" (Lubrizol Corporation); or its sodium or ammonium salt. Other 
water-soluble monomers for the production of polymer water-in-oil 
emulsions, in accordance with the invention, are acrylic and methacrylic 
esters of amino alcohols, such as dimethylaminoethyl methacrylate, which 
can also be used for polymerization in neutralized or quaternized form. 
Other usable water-soluble monomers are hydroxy-alkyl acrylates and 
methacrylates as, for instance, ethylene glycol monoacrylate and 
2-hydroxy-propyl methacrylate. Also included are 
.alpha.,.beta.-unsaturated monomers which do not belong to the acrylic or 
methacrylic series and are soluble in the water phase, such as maleic 
acid, vinyl sulfonic acid or vinyl benzene-sulfonic acid, their alkali and 
ammonium salts or N-vinyl pyrrolidone. 
Preferred monomers are acrylamide, methacrylamide, "AMPS", sodium acrylate, 
sodium methacrylate, ammonium acrylate, 2-dimethylaminoethyl methacrylate 
hydrochloride, 2-trimethylammoniumethyl methacrylate chloride, 
2-trimethylammoniumethyl acrylate chloride, N-trimethylammoniumpropyl 
methacrylamide chloride and the corresponding trimethylammonium 
methosulfates. The acrylamide copolymers, used primarily as flocculants, 
contain one or more comonomers in quantities of 2 to 80% by weight related 
to all polymers. 
For the dispersion of the aqueous monomer solution in the continuous oil 
phase, water-in-oil emulsifying agents with HLB values from 1 to 10, and 
preferably from 2 to 8, are used. (The Atlas HLB System, Atlas Chemie 
GmbH, EC10G July 1971. HLB-System, Rompps Chemie Lexicon, 8th edition, p. 
1715, Frankh'sche Verlagshandlunq, Stuttgart). 
Polymer emulsifiers are described in DE-C 24 12 266. Other known 
emulsifiers are, e.g., sorbitan-monostearate and sorbitan-monooleate. 
Emulsifiers are added to the oil phase in quantities of 0.1 to 30%, and 
preferably 1 to 15% by weight, as related to the entire emulsion. 
The sedimentation stability of the polymer water-in-oil emulsion is 
improved by adding 0.1 to 10% by weight of a wetting agent whose HLB value 
is more than 10 to the emulsion to be polymerized. Hydrophylic, 
water-soluble products, for instance ethoxylated alkyl phenols, such as 
ethoxylated nonyl phenol with a degree of ethoxylation of 5 to 20; or 
soaps of fatty acids with 10 to 22 carbon atoms are suitable. The wetting 
agent is generally dissolved or suspended in the organic phase but it can 
also be added to the aqueous phase or to the finished polymer water-in-oil 
emulsion. 
The appropriate addition of water-soluble acids, such as adipic acid or 
adipic acid in a mixture with other acids to transform the polymer 
emulsion into an aqueous solution, and their use in accordance with DE-C 
22 38 017 and DE-A 32 10 752, take place already when the organosol is 
being made. 
The share of the aqueous, dispersed phase in the monomer water-in-oil 
emulsion is in the range of 40 to 80% by weight, wherein the share of the 
water-soluble monomers of this phase is in the range of 20 to 85%, and 
preferably 50 to 80% by weight. 
The polymerization of the monomers is carried out in the presence of the 
usual polymerization initiators. One may use, for instance, peroxides such 
as dibenzoyl peroxide, dilauroyl peroxide, hydrogen peroxide, ammonium 
persulfate, or azo compounds such as azodi-isobutyronitrile, or 
oxidation-reduction (redox) systems such as ammonium persulfate/ferro 
sulfate, dibenzoyl peroxide/N,N-dimethyl-p-toluidine. The polymerization 
temperature depends on the initiator used. It may be in the range of 
5.degree. C. to about 100.degree. C. It is appropriate to polymerize 
initially with a redox system with low conversion percentages and then to 
polymerize at higher temperatures with a peroxide initiator, for instance, 
which may have been part of the redox system to complete polymerization. 
The completion of polymerization is indicated when the emulsion bath 
temperature remains constant. 
Other features of the invention will become apparent in the course of the 
following descriptions of exemplary embodiments which are given for 
illustration of the invention and are not intended to be limiting thereof. 
EXAMPLES 
Example 1 
Into a monomer emulsion, made by stirring an aqueous monomer phase with the 
composition of: 
83.6 g: acrylamide 
195.6 g: 2-trimethylammoniumethyl methacrylate chloride 
54.9 g: distilled water 
14.4 g: mixture of about 45% by weight glutaric acid, about 35% by weight 
adipic acid and about 20% by weight succinic acid 
and an oil phase with the composition of: 
205.2 g: bis-(2-ethylhexyl) adipate (commercial product Vestinol 
(registered trademark) OA of the Chemische Werke Huls AG) 
21 g: polymer emulsifier in accordance with DE-C 24 12 266, consisting of a 
mixed polymer of 30% by weight dimethylaminoethyl methacrylate and 70% by 
weight of a mixture of C.sub.10 -C.sub.20 alkyl methacrylates 
from which dissolved oxygen is largely eliminated by nitrogen degassing, is 
added 0.013 g ammonium persulfate as a 1% aqueous solution and 0.012 g 
FeSO.sub.4 as a 1% aqueous solution, with continued stirring at a 
temperature between 20.degree. to 30.degree. C. The temperature of the 
emulsion rose to 35.degree. to 41.degree. C. At this temperature the same 
amounts of ammonium persulfate and FeSO.sub.4 are again added as described 
above. The end of polymerization is indicated when the emulsion bath 
temperature remains constant. 
The polymer emulsion is filtered through a wire net. It is self-converting 
and the viscosity of a 1% aqueous solution is about 9,000 mpas. 
Example 2 
A monomer emulsion produced from an aqueous phase corresponding to that of 
Example 1 and an oil phase with the composition: 
138.2 g: bis-(2-ethylhexyl) adipate (Vestinol (registered trademark) OA) 
52.7 g: stearic acid methyl ester 
35.3 g: polymer emulsion corresponding to Example 1 
is increasingly polymerized after degassing with nitrogen as in Example 1, 
at a temperature range of 40.degree. to 55.degree. C. After filtering 
through a wire net, an emulsion is obtained with a viscosity of 4,400 mpas 
which is self-converting and shows a viscosity of 6,600 mpas of the 1% 
aqueous solution. 
Example 3 
To a monomer emulsion produced with an aqueous monomer phase of the 
composition: 
168 g: 2-trimethylammoniumethylmethacrylatechloride 
102 g: Water 
12.4 g: of the dicarboxylic acid mixture as given in Example 1 
and of the oil phase with the composition: 
138.2 g: mineral oil (Shell oil G 07) 
35.2 g: (2-ethylhexyl) adipate (Vestinol (reg. trademark) OA) 
17.6 g: isodecanol 
35 g: polymer emulsifier corresponding to Example 1 
are added 0.31 g ammonium persulfate as a 1% aqueous solution at 40.degree. 
C., after degassing with nitrogen and continued stirring. Polymerization 
is carried out at temperature of 45.degree. to 48.degree. C. To the final 
polymerization, 0.31 g ammonium persulfate as a 1% aqueous solution is 
again added and then 0.005 g FeSO.sub.4 as a 1% aqueous solution. 
The viscosity of the organosol thus obtained is 1,700 mpas. It is 
self-converting with a viscosity of the 1% aqueous solution of 7,500 mpas. 
Obviously, numerous modifications and variations of the present invention 
are possible in light of the above teachings. Therefore, it is to be 
understood that within the scope of the appended claims, the invention may 
be practiced otherwise than as specifically described.