d US005393461A United States Patent (19) 11 Patent Number: 5,393,461 Fillipova 45 Date of Patent: Feb. 28, 1995

54 PREPARATION OF STABLE AOUEOUS 4,997,864 3/1991 Waters ...... 523/319 EMULSIONS OF WATER-INSOLUBLE 5,032,390 7/1991 Iwaya et al...... 424/59 5,066,485 11/1991 Brieva et al...... 424/63 PARTICLES 5,091, 188 2/1992 Ahynes ...... 424/450 75 Inventor: Irina V. Fillipova, Bethlehem, Pa. 5,171,572 12/1992 Suganuma et al...... 424/401 73) Assignee: RTD Corporation, Bethlehem, Pa. 5,250,289250,289 10/1993 Boothroydhrowd et al...... 424/59/ 21 Appl. No.: 131,448 FOREIGN PATENT DOCUMENTS - a - - 9 22 Filed: Oct. 4, 1993 610397 12/1960219 candCanada ...... 523/502M 51) Int. Cl...... bo so cosko Primary Examiner-Richard D. Lovering C08K 3/22 57 ABSTRACT 52 U.S. Cl...... 252/314; 106/23 C; A process for preparing an emulsion of water-insoluble 106/472; 252/310; 252/311; 252/312; particles useful in the cosmetic, pharmaceutical, paint 252/315.2; 514/937; 514/938; 514/942; and ink industries comprising: 58 Field of Search 514/952;252/30, 523/502; 311, 312,523/505 314 treating the water-insoluble particles with a wetting 252/315.2, 514/937,938,942, 952;523/502,505 106/23 C, combiningagent in anthe organic water-insoluble solvent; particles with- an oily- or polymeric substance to obtain an oily suspen 56) References Cited sion; U.S. PATENT DOCUMENTS preparing an aqueous ision of a combination of 2,764,499 9/1956 Porter, Jr...... 252/314 X R. agents; I ti ith the oil 3,133,893 5/1964 Newman ...... 524/720 combining the aqueous solution with the oily suspen 3,544,500 12/1970 Osmond et al. .. 428/402.24 sion to form an emulsion. 3,580,880 5/1971 Clarke et al...... 524/457 4,421,660 12/1983 Solc nee Hajna ...... 252/62.54 7 Claims, No Drawings 5,393,461 1. 2 b) mixing of 1 to 90% w/w of a finely divided pow PREPARATION OF STABLE AOUEOUS der having 50 to 100 nm particle size distribution EMULSONS OF WATER-INSOLUBLE with the wetting solution to obtain a dispersion; PARTICLES c) mixing the dispersion with of from about 10 to about 99% w/w of an oily/polymeric substance BACKGROUND OF THE INVENTION dissolved in an organic solvent to obtain an oily suspension; Field of the Invention d) preparing an aqueous solution by mixing in water This invention relates to stable aqueous emulsions of of from about 0.1 to about 2.0% w/w of an emulsi water-insoluble particles useful in the cosmetic, phar 1O fying agent selected from the group consisting of a maceutical, paint and ink industries. cationic, nonionic, anionic and zwitterionic surface 2. Reported Developments active agent by stirring for about 30 to 90 minutes The prior art has expended great effort to provide at a temperature of from about 60 to about 70° C. stable emulsions of particulates for various applications to obtain an aqueous solution; in the above-mentioned industries. The main problem 5 e) cooling the aqueous solution to room temperature; encountered with emulsions is inadequate physical sta f) adding from about 20 to about 35% w/w of the bility whereby the particulates flocculate, agglomerate oily/polymeric suspension to from about 65 to and settle-out from the emulsions and become non about 80% w/w of the aqueous solution and mix uniform. ing them for about 20 to 30 minutes at room tem U.S. Pat. No. 3,133,893 discloses pigment particles perature to obtain an aqueous suspension; coated with a polymer for coloring of plastics, resins g) emulsifying the aqueous suspension by using emul and synthetic fibers. The polyner is a thermoplastic, sifying means, such as a sonifier to obtain an emul linear, addition polymer of a compound containing the sion which contains organic solvents used in step polymerizable group of (a); and 25 h) removing the organic solvent by stirring/evapora tion or other means to obtain a final emulsion essen N / tially free of the organic solvent. C The concentration of the final emulsion may be con / N trolled by either varying the percentage of the oily 30 suspension obtained in step (c), added to the aqueous U.S. Pat. No. 3,544,500 discloses a process for encap solution obtained in step (d), or by evaporation of the sulating solid particles for use in insecticides, pharma water from the final emulsion obtained in step (h). ceuticals and powders. The process comprises adsorb DETALED DESCRIPTION OF THE ing a polymer on the surface of the particles and provid 35 ing a stabilizer having an anchor group which become INVENTION associated with the adsorbed polymer on the surface An important requirement in the preparation of the and a pendant hydrophilic component solvated by the emulsion of the present invention is the use of narrow aqueous phase and provides a stabilizing sheath around distribution size particles, namely of from about 50 or the solid particles. less nm to about 100 nm. U.S. Pat. No. 3,580,880 discloses a process for making dispersions of particulate solids by dispersing the partic Water-insoluble Particles ulate solids in a lipophilic or a hydrophilic liquid in the The finely-divided particles used in the present inven presence of a polymeric amphipathic stabilizer which tion should be essentially water-insoluble. Such parti associates with the surface of the particles and provides 45 cles may be inorganic, organic and polymeric particles a solvated steric barrier around the particles. depending on the intended end use of the emulsion. The U.S. Pat. No. 4,421,660 discloses a process for prepar required particle size is achieved by conventional tech ing compositions comprising the steps of: niques, such as by grinding, milling or comminution. emulsifying a hydrophilic emulsion polymerizable Examples of inorganic particles include, but are not 50 limited to zinc oxide, talc, kaolin, mica, titanium diox monomer in an aqueous dispersion of discrete parti ide, zirconium oxide, iron oxides, aluminum hydroxide, cles of an inorganic solid; and aluminum chloride, calcium phosphate, magnesium polymerizing the monomer to coat the discrete parti oxide, aluminum silicate, calcium silicate, titanium diox cles of the inorganic solid. ide, bentonite, asbestine, china clay, calcium carbonate, While the above-listed and similar approaches made 55 magnesium carbonate and dolomite. great strides in satisfying the needs of various industries, Examples of organic and polymeric particles include, they do have some shortcomings including the com but are not limited to, starch, polyamide resin, polyole plexity of the processes and less than the desired stabil fin resins, polystyrene, polystyrene resin, acrylic resin, ity in the products produced thereby. The present in epoxy resin, vinyl resin, vinylidene resin, polyurethane vention intends to provide solutions for these and other resin, natural rubber, synthetic rubber, chitin, chitosan, shortcomings. fibroin, keratin and cellulose. Some of these materials are extensively used in the SUMMARY OF THE INVENTION various industries for various purposes. For example: The present invention provides a process for making zinc oxide is used industing powders, pastes, ointments, an emulsion comprising the steps of: 65 creams and lotions; talc, titanium dioxide and zinc oxide a) preparing a solution of from about 0.01 to about are used in cosmetic powders; titanium dioxide and zinc 5% w/w of a wetting agent in an organic solvent to oxide are used as sunblockers; antimony oxide, red OX obtain a wetting solution; ide, lemon chrone, cobalt blue, metal containing or 5,393,461 3 4 ganic pigments and carbon blacks are used as pigments ethylene oxide wherein the ethylene oxide is present in in the paint and printing industries. equal amounts of from about 30 to 60 moles of ethylene When materials are ground, milled or comminuted to oxide per mole of alcohol; and carboxylic esters formed very small particle size, air is adsorbed onto the surface by the reaction of fatty acids with polyhydric alcohols. of the particles. The adsorbed air prevents or at least greatly reduces the wettability of the particles thereby Other nonionic include: polyoxyethylene hindering uniform suspensions of the particles in a liquid p-tert-octylphenyl ether and polyoxyethylene mono vehicle. For this reason a wetting agent must be used to hexadecyl ether. replace solid-air interface with a solid liquid interface. Zwitterionic surfactants include N-dodecyl-N,N- In non-aqueous solutions the molecules of a wetting 10 dimethyl betaine. agent are oriented with the hydrophobic group towards Preferred emulsifying agents include: potassium lau the molecules of the nonaqueous solution thereby in rate, , lauryl sulfate, creasing the hydrophobicity of the solid particles and magnesium laurylsulfate, triethanolamine laurylsulfate, rendering them more wettable. The prior art has uti sulfated castor oil, dialkylglycerylphosphorylcoline, lized aqueous, oily, waxy or volatile organic vehicles 15 sodium lauryl sulfoacetate, sodium dodecyl benzenesul for dispersing solid particles for obtaining the desired fonate, polyoxyethylated lauryl, hexadecyltrime effects in the various end products. While the use of thylammonium bromide or chloride, ethoxylated pa these approaches and materials provided improvements raoctylphenol, 2-ethyl-hexyl alcohol, ethoxylate and in emulsions, the need for further improvements are cetyltrimethyl . obvious for those practicing in the cosmetic, paint, 20 The surfactants used as emulsifying agents are prefer pharmaceutical and printing industries. ably used with a co-. The ratio of surfactant to Wetting Agents co-surfactant should be in the range of 1:1 to 1:3 for best The wetting agents used in an organic solvent in step results. (a) of the process to provide a wetting solution include 25 Co-surfactants include: lauryl-, cetyl-, miristyl-, stea but are not limited to: sodium dodecyl benzene sulfo ryl, oleyl- and isocetyl-alcohols, lanolin and its deriva nate, alkyl benzene sulfonate, sodium lauryl sulfate, tives, hexadecane, 1-pentanol, hexanol and decane. sodium dioctyl sulfosuccinate, sodium-dilauryl phos In the process the co-surfactant must be added to the phate, lanolin and lanolin derivatives, sodium mono aqueous phase together with the surfactant. glyceryl lauryl sulfate, sodium methyl oleoyl taurate, 30 sodium octoxynol-2-ethanesulfonate, sodium dioctyl The Oily/Polymeric Substance sulfosuccinate, sodium octoxynol-2-ethane sulfonate, The oily substances used in the present invention di-3-naphthylmethane disulfate, sulfated castor oil, so include, but are not limited to, oils and fats, such as: dium secondary alcohol sulfate, sodium alkylaryl sulfo fatty alcohols, for example, cetyl alcohol, lauryl alcohol nate (AEROSOL OS), dialkylsulfosuccinate (AERO 35 and stearyl alcohol; vegetable oils, for example, olive SOL MA), dioctyl ester of sodium sulfosuccinate oil, grape seed oil, safflower oil, soybean oil, corn oil, (AEROSOL OT), sodium-2-ethylhexyl sulfate (TER rapeseed oil, avocado oil, almond oil, castor oil, peanut GITOL 08), sodium-7-ethyl-2-methyl-undecyl-4-sulfate oil, coconut oil, and cottonseed oil; animal fats, for (TERGITOL 04), and sodium-3,9-diethyltridecyl-6-sul example, tallow, mink oil, and hardened oil; waxes, for fate (TERGITOL 07). example, shellac, beeswax, lanolin, liquid lanolin, Emulsifying Agents carunauba wax and candelilla wax; and hydrocarbons, The emulsifying agents used in an aqueous solution in for example, liquid paraffin and squalane, and petrola step (d) of the process include, but are not limited to: tum. Cationic surfactants which include long-chain amino 45 condensates with ethylene oxide and quaternary ammo The Organic Solvent nium compounds, such as cetyl trimethyl ammonium An organic solvent or a mixture of organic solvents is bromide and dodecyl dimethyl , used to dissolve the wetting agent as well as to dissolve hexadecyl (cetyl) trimethylammonium bromide, dode the oily/polymeric substance. The type of organic sol cyl pyridinium chloride and dodecylamine hydrochlo 50 vent used depends on the solubility of the wetting agent ride. and the oily/polymeric substance. Preferred solvents Anionic surfactants include: salts of aliphatic monoes are those that volatilize easily and do not leave undesir ters of sulfuric acid and soaps, such as sodium lauryl able odor. Examples of solvents include ethyl alcohol, sulphate and sodium heptadecyl sulphate; sulfonated methyl alcohol, isopropyl alcohol, chloromethane, di aromatic agents such as alkylbenzene sulfonic acids and 55 salts thereof, such as tridecylbenzene sulphonic acid chloromethane, chloroform, carbon tetrachloride, and the sodium and amino salts of dodecylbenzene sul methyl ethyl ketone, methyl isobutyl, ketone, ethyl phonic acid; alkyl naphthalene sulfonates, such as so acetate, perchloroethylene, acetone and glycol ethers. dium butylnaphthalene sulphonate, sulphosuccinates Comminution of the Particles such as sodium dioctyl sulphosuccinate and N-acyl-N- alkyl fatty acid taurates; sulfated polyoxyethylated al The particles used in the present invention should be cohols; and sulfated oils. in the range of from about 50 to about 100 nm or less. Non-ionic surfactants which include: polyethylene The required particle size powder may be obtained by oxide condensates of alkylphenols, such as octyl cresol, using methods of particle-size reduction known in the octyl phenol or nonyl phenol with ethylene oxide; eth 65 art, such as by grinding, sonification, high pressure and oxylated aliphatic alcohols which are the condensation shear and high speed impact in air. products of aliphatic alcohols having from about 8 to 18 The present invention will now be illustrated by the carbon atoms, for example, oley or cetyl oxide, with following examples. 5,393,461 5 6 d&e) 0.5 g of sodium dodecyl sulfate and 1.5 g of EXAMPLE stearyl alcohol were dissolved in 98 g of deionized Paint and Ink Preparations water at a temperature of 70° C., followed by cool a) 0.01 g of alkylbenzylsulfonate was dissolved in 12 ing to room temperature to obtain an aqueous solu ml of acetone to obtain a wetting solution. tion. b) 2 g of carbon black was mixed with the wetting The remaining process steps were performed as de solution to obtain a dispersion. scribed in Example 1. c) The dispersion was mixed with a solution of 2 g of Table I shows typical preparations useful in the paint epoxide resin and 2 g of a vinyl polymer in dichlo and ink industries wherein ingredients from the columns romethane to obtain an oily suspension. 0 are combined according to the process described in d&e) 0.2 g of sodium lauryl sulfate and 0.6 g of cetyl Example 1. TABLE I Paint and Ink Preparations 0.01 to 5% w/w 2 to 18% w/w of 0.1 to 2.0% w/w 2 to 18% w/w of 20-80 in of Wetting Agent Oily Substance of Emulsifying Particulate Organic Solvent selected from the selected from Agent selected selected from Selected from the group the group from the group the group group Alkyl-benzene- Phenolic resin, Sodium lauryl Carbon black, Chloronethane, sulfonate, Dioctyl Epoxide resin, sulfate, Copper Dichloro ester sodium Chiorinated Sodium dodecyl carbonate, methane, sulfosuccinate Rubber, sulfate, Manganese Chloroform, (AEROSOL OT), Amino Resin, Cetyl alcohol, Dioxide, Carbon tetra Sodium Urethane resin, Steary alcohol, Zinc chronate, chloride, alkylary Urethane oil, Alkane Barium Methyl ethyl sulfonate Polyurethane hexadecane chromate, ketone, (AEROSOLOS), unsaturated Cadmium Methyl isobutyl Diethyl polyester, sulfide, ketone, sulfosuccinate Nitrocellulose, Iron oxide, Ethyl acetate, (AEROSOL MA), Acrylic Ultramarine, Perchloro Sodium-2- polymer, Prussian blue, ethylene, ethylarylsulfate Acrylic- Cobalt blue, Isopropanol, (TERGITOL 08), copolymer, Chronium Acetone, Sodium-3,9- Vinyl polymer, oxide, Methanoi, diethyltridecyl-6- Vinyl co- Red iron oxide, Ethanoi sulfate polyner, Titanium Butanol (TERGITOL 07), Styrene dioxide, Propanol Sodium-7-ethyl- polyner, Zinc oxide, Iso-propanol 2-methyl- Styrene co- Antimony Iso-butanol undecyl-4-sulfate polymer oxide, (TERGITOL 04) Lead carbonate Lanoin triethanolamine Steatate

alcohol were dissolved in deionized water at a EXAMPLE 3 temperature of 65 C., followed by cooling to room Dermatological/Cosmetic Preparation temperature to obtain an aqueous solution. 50 a) A 5% w/w dioctyl ester sodium sulfosuccinate f&g) The suspension (c) and aqueous solution (d&e) (AEROSOL OT) in ethanol was prepared to ob were then added together and stirred for 15 to 30 tain a wetting solution. minutes at room temperature and emulsified by a b) 10 g of zinc oxide was mixed with 50 ml of the sonifier. wetting solution to obtain a dispersion. h) The organic solvents, acetone and dichlorometh 55 c) The dispersion was mixed with a solution of 10 g of ane were removed from the emulsion by evapora cetyl alcohol in 50 ml of chloromethane to obtain tion using a magnetic stirrer. an oily suspension. EXAMPLE 2 d&e) 0.35 g of sodium lauryl sulfate and 1.0 g of hexadecane were dissolved in 300 g deionized Paint and Ink Preparations 60 water at a temperature of 60° C. and stirred for 40 a) 0.4 g of alkylaryl sulfonate (AEROSOL OS) was minutes, followed by cooling to room temperature dissolved in 30 ml of carbon tetrachloride to obtain to obtain an aqueous solution. a wetting solution. The remaining process steps were performed as de b) 18 g of manganese dioxide was mixed with the scribed in Example 1. wetting solution to obtain a dispersion. 65 Table II shows typical preparations useful in derma c) The dispersion was mixed with a solution of 18 g of tology wherein ingredients from the columns are con chlorinated rubber and 18 g of an acrylic polymer bined according to the process described in Example 1. in chloromethane to obtain an oily suspension. 5,393,461 7 TABLE I Dernatological/Cosmetic Preparations 0.01 to 5% w/w of 2 to 8% w/w of 0.1 to 2% ww of 2 to 18% w/w of 20-80 in of Wetting Agent Oily Substance Emulsifying Particulate Organic Solvent selected from the selected from Agent selected selected from selected from the group the group from the group the group group Alkyl-benzene- Cetyl alcohol, Sodium lauryl Zinc oxide, Chloromethane, sulfonate, Dioctyl Olive oil, sulfate, Starch Dichloro ester sodium Cottonseed oil, Sodium dodecyl containing an methane, sulfosuccinate Sesame oil, sulfate, antiseptic Chloroform, (AEROSOL OT), Glycerides, Hexodecane, therein, Carbon tetra Sodium Liquid paraffin, Cetyl alcohol, Talc, chloride alkylaryl Petroleun wax, Stearyl alcohol Calamine, Butanol sulfonate Polyglycol Titanium Propanol (AEROSOLOS), esters dioxide, Iso-propanol Diethyl Magnesium Iso-butanol sulfosuccinate carbonate (AEROSOL MA), Sodium-2- ethylarylsulfate (TERGITOL 08), Sodium-3,9- diethyltridecyl-6- sulfate (TERGITOL 07), Sodium-7-ethyl 2-methyl undecyl-4-sulfate (TERGITOL 04) Lanolin triethanolamine Stearate Preparations of the present invention may include other ingredients commonly used in emulsions. For 30 example, the dermatological formulations may include undecyl-4-sulfate, and sodium-3,9-diethyltridecyl topical drugs for the treatment of diseases. Both the 6-sulfate, in an organic solvent selected from the dermatological and cosmetic preparations ordinarily group consisting of ethyl alcohol, methyl alcohol, include preservatives against microbial growth exam isopropyl alcohol, chloromethane, dichlorometh ples of which include methyl, ethyl, propyl, and butyl 35 ane, chloroform, carbon tetrachloride, methyl parabens. ethyl ketone, methyl isobutyl ketone, ethyl acetate, Penetration enhancers may also be included in the perchloroethylene, acetone and glycol ethers to dermatological formulations, such as propylene glycol, obtain a wetting solution; glycerin, tetrahydrofurfunyl alcohol, dimethylacetam b) mixing of 1 to about 90% w/w of a finely divided ide, dimethylformamide, pyrrollidones, alkyl sulfoxides, powder having 50 to 100 nm particle size distribu phosphine oxides and sugar esters. tion or less with the wetting solution to obtain a Stability studies at room and higher temperature dispersion; were conducted to ascertain shelf-life of the emulsions c) mixing the dispersion with from about 10 to about of the present invention. At room temperature the emul 99% w/w of an oily or polymeric substance dis sions remained homogeneous for at least four months, 45 solved in an organic solvent selected from the while at higher than room temperature, such as at group consisting of ethyl alcohol, methyl alcohol, 40-50 C., they remained homogeneous for about 30 to isopropyl alcohol, chloromethane, dichlorometh 40 days. Upon vigorous agitation the emulsions, both at ane, chloroform, carbon tetrachloride, methyl room and at higher temperatur, regained their initial ethyl ketone, methyl isobutyl ketone, ethyl acetate, homogenity and were then ready for their intended end 50 perchloroethylene, acetone and glycol ethers to Se. obtain an oily suspension; The invention, having been fully described, it will be d) preparing an aqueous solution by mixing in water apparent to one skilled in the art that changes and modi of from about 0.1 to about 2% w/w of an emulsify fications can be made thereto without departing from ing agent selected from the group consisting of a the spirit and scope thereof. 55 cationic, nonionic, anionic and zwitterionic surface What is claimed is: active agent to obtain an aqueous solution; 1. A process for preparing an emulsion comprising e) adding of from about 20 to about 35% w/w of the the steps of: oily suspension to about 65 to 80% w/w of the a) preparing a solution of from about 0.01 to 5% w/w aqueous solution to obtain an aqueous suspension; of a wetting agent selected from the group consist and ing of alkyl benzene sulfonate, sodium lauryl sul f) emulsifying the aqueous suspension. fate, sodium dilauryl phosphate, lanolin, sodium 2. The process of claim 1 further comprising remov monoglyceryl lauryl sulfate, sodium methyl oleoyl ing said organic solvent from said aqueous suspension. taurate, sodium octoxynol-2-ethanesulfonate, di-p3 3. The process of claim 1 wherein said finely divided naphthylmethane disulfate, sulfated castor oil, so 65 powder is selected from the group consisting of inor dium secondary alcohol sulfate, sodium alkylaryl ganic, organic and polymeric particles. sulfonate, dialkylsulfosuccinate, dioctyl ester of 4. The process of claim 1 wherein said finely divided sodium sulfosuccinate, sodium-7-ethyl-2-methyl powder is selected from the group consisting of zinc 5,393,461 10 oxide, titanium dioxide, talc, aluminum hydroxide, alu b) mixing of 1 to 90% w/w of a finely divided pow minum chloride, calcium phosphate, magnesium oxide, der having 50 to 100 nm particle size distribution with the wetting solution to obtain a dispersion; aluminum silicate, starch, calcium carbonate, magne c) mixing the dispersion with of from about 10 to sium carbonate, natural rubber, synthetic rubber, cellu about 99% w/w of an oily or polymeric substance lose, polyamide resin and polyolefin resin. dissolved in an organic solvent selected from the 5. The process of claim 1 wherein said emulsifying group consisting of ethyl alcohol, methyl alcohol, agent is selected from the group consisting of potas isopropyl alcohol, chloromethane, dichlorometh sium laurate, sodium dodecyl sulfate, ammonium lauryl ane, chloroform, carbon tetrachloride, methyl sulfate, magnesium laurylsulfate, triethanolamine lauryl O ethyl ketone, methyl isobutyl ketone, ethyl acetate, sulfate, sulfated castor oil, dialkylglycerylphosphoryl perchloroethylene, acetone and glycol ethers to choline, sodium lauryl sulfoacetate, sodium dodecyl obtain an oily emulsion; benzenesulfonate, polyoxyethylated lauryl, hexadecyl d) preparing an aqueous solution by mixing of from trimethylammonium bromide or chloride, ethosylated about 0.1 to about 2% w/w of an emulsifying agent para-octylphenol, 2-ethyl-hexyl alcohol ethoxylate and 15 selected from the group consisting of potassium cetyltrimethyl ammonium persulfate. laurate, sodium dodecyl sulfate, ammonium lauryl 6. The process of claim 1 wherein said oily or poly sulfate, magnesium lauryl sulfate, triethanolamine meric substance is selected from the group consisting of lauryl sulfate, sulfated castor oil, dialkylglyceryl cetyl alcohol, lauryl alcohol, stearyl alcohol, olive oil, phosphorylcholine, sodium lauryl sulfoacetate, 20 sodium dodecyl benzenesulfonate, polyoxye corn oil, tallow, shellac, lanolin, beeswax, polyure thylated lauryl, hexadecyltrimethyl-ammonium thane, phenolic resin, epoxide resin, nitrocellulose, bromide or chloride, ethoxylated para-octyl acrylic polymer and styrene polymer. phenol, 2-ethyl-hexyl alcohol ethoxylate and cetyl 7. A process of making an emulsion comprising the trimethyl ammonium persulfate, and from about steps of: 25 0.1 to about 6% of a co-surfactant selected from the a) preparing a solution of from about 0.01 to 5% w/w group consisting of: lauryl-, cetyl-, myristyl, stea of a wetting agent selected from the group consist ryl-, oleyl- and isocetyl-alcohols, lanolin, hexa ing of alkyl benzene sulfonate, sodium lauryl sul decane, 1-pentanol, hexanol and decane by stirring fate, sodium dilauryl phosphate, lanolin, sodium for about 30 to 90 minutes at a temperature of from monoglyceryl lauryl sulfate, sodium methyl oleoyl 30 about 60° C. to about 70 C. to obtain an aqueous taurate, sodium octoxynol-2-ethanesulfonate, di-g- solution; naphthylmethane disulfate, sulfated castor oil, so e) cooling the aqueous solution to room temperature; f) adding from about 20 to about 35% w/w of the oily dium secondary alcohol sulfate, sodium alkylaryl suspension to from about 65 to about 80% w/w of sulfonate, dialkylsulfosuccinate, dioctyl ester of the aqueous solution and mixing them for about 20 sodium sulfosuccinate, sodium-7-ethyl-2-methyl to 30 minutes at room temperature to obtain an undecyl-4-sulfate, and sodium-3,9-diethyltridecyl aqueous suspension; 6-sulfate, in an organic solvent selected from the g) emulsifying the aqueous suspension by using an group consisting of ethyl alcohol, methyl alcohol, emulsifying technique to obtain an emulsion which isopropyl alcohol, chloromethane, dichlorometh contains organic solvents used in steps (a and c); ane, chloroform, carbon tetrachloride, methyl and ethyl ketone, methyl isobutyl ketone, ethyl acetate, h) removing the organic solvent to obtain a final perchloroethylene, acetone and glycol ethers to emulsion essentially free of the organic solvent. obtain a wetting solution; k k ck ck 2k 45

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