PROCESS FOR PRODUCING A POLYMER WATER-IN-OIL EMULSION

Abstract: A semi-continuous process for producing a polymer water-in-oil emulsion which comprises: (a) combining: (i) an aqueous solution comprising at least one water-soluble monomer and (ii) a mixture compris­ ing a hydrophobic liquid, a hydrophobic monomer and an oil-soluble surfactant; (b) homogenizing the mixture from (a) to form a water-in-oil emulsion; (c) deoxygenating said homogenized water-in-oil emulsion; (d) continually adding the homogenized water-in-oil emulsion to a reactor while adding a deoxygenated initiator solution; (e) heating the mixture from (d) under polymerization a conditions so as to form a polymer water-in-oil and (f) recovering a polymer water-in-oil emulsion.

Description: PROCESS FOR PRODUCING A POLYMER WXTER-IN-OIL EMULSION This invention is directed to a semi-continuous process for producing a copolymer water-in-oil emulsion. Water-in-oil emulsion processes, in which a water-soluble monomer is emulsified in an oil phase and polymerized therein, are well known in the art. For exarrple, U.S. Patent 3,284,393 describes such a process wherein water-soluble monaners are polymerized to high molecular weight polymers or copolymers utilizing a water-in-oil emulsion polymerization procedure. In the polynerization process described in said patent, one or a plurality of water-soluble monsters, or an aqueous solution thereof, is emulsified in an oil phase by means of a water-in-oil emulsifier and emulsion polymerized under free radical farming conditions to form a polymeric latex in which the oil phase is the dispersion medium. U.S. 3,284,393 further states that the inert hydrophosic liquid, in which a water-in-oil emulsifying agent is dissolved, is added to a reactor, and then an aqueous solution or itoncrer, mixed monomers, or mono- mers per se, is added to the oil phase until the monomer phase is emulsion fied in the oil phase and the polymerization is carried out. The patent states that the order of addition of reaction media ingredients is not important. The examples in the patent describe a batch reaction, i.e. a reaction in which all of the ingredients are added to the reactor and polymerization takes place. However, it is difficult to control the compositional uniformity of the product produced by a batch reaction and also it is difficult to control the exotherm of the reaction. Difficulty in controlling uniformerly results in a broad and often erratic compositional distribution. Inability to control the exotherm of the reaction results in the formation of undesirable low molecular weight polyeer, or a branched polymer, and/or agglomeration of the reaction mixture. It has now been found that the product copolymer water-in-oil emulsion produced by the semi-continuous process of this invention has high cwr positional uniformity. The product formed by the semi-continuous process of this invention is much more uniform than that produced by a batch process. Also, the process of this invention allows safer control of the exotherm. Another advantage of the semi-continuous process is that the polymerization is carried out at a faster rate at the initial stage of polymerization, which results in a shorter reaction time, and a more stable water-in-oil emulsion than can be achieved by carrying out the polymeri- zation by a batch process, in reactors having identical cooling capabilities. By the term "semi-cont mucus" as used herein, is meant a process whereby the monomer emulsion is fed continuously into the reactor during the course of polymerization. In contradistinction, all the ittrnmr emulsion is charged to a reactor at the beginning of the reaction in a batch process. This invention is directed to a semi-continuous process for pro- ducing a polymer water-in-oil emulsion which process comprises: (a) combining: (i) an aqueous solution comprising at least one water-soluble monomer, and (ii) a mixture comprising a hydrophobic liquid, a hydrophobic monaner and an oil-soluble surfactant: : (b) hcmogenizing the mixture fran (a) to form a water-in-oil emulsion; (c) deoxygenating said homogenized water-in-oil emulsion; (d) continually adding the homogenized water-in-oil emulsion to a reactor while adding thereto a deoxygenated initiator solution; (e) heating the mixture fran (a) under polymerization conditions so as to form a polymer water-in-oil emulsion; and (f) recovering a polymer water-in-oil emulsion. A water-soluble surfactant is generally added to the recovered water-in-oil emulsion (f). These water-in-oil emulsions are solubilized, or inverted, in the presence of water so that the polymer readily goes into solution. These solutions are suitable for use as flocculants for water Pu- rification, such as to facilitate the settling of particles in phosphate slimes. A process for flocculating phosphate slimes is described in U.S. Patent Application Serial No. (Docket No. 13,300) filed in the names of M. Rosen et al, titled "Process for Flocculating Phosphate Containing Slimes" and filed on the same date as this application. In the first step of the process of this invention, an aqueous solution containing a water-soluble monomer is combined with a mixture containing a hydrophobic liquid, a hydrophobic itonotner and an oil-soluble surfactant. This cattination of materials is homogenized to form a waterin-oil emulsion. The aqueous solution contains a mixture of water soluble monomers. These monaners have a water solubility of at least 5 weight percent and include acrylamide, methacrylamide, acrylic acid, methacrylic acid, and their alkali metal salts, aminoalkyl acrylate, aminoalkyl methacrylate, dialkylaminoalkyl acrylate, benzyl sulfonates, maleic anhydride, and the like. The e preferred monomers are acrylamide and acrylic acid. If acrylic acid is used as a monomer it is reacted with a base, preferably with an equivalent amount of base, such as sodium hydroxide, so that the sodium acrylate solution has a pH of from about 5.0 to about 10.0, preferably from about 6.5 to about 8.5, depending on the type and amount of base employed. This solution is combined with another water soluble monomer, such as acrylamide, and then with water to form the aqueous phase. The aqueous phase contains from about 45 to about SO, preferably from about 48 to about 78 weight percent of a combination of water and water soluble monomer(s). The mixture wnich is combined with the aqueous solution containing tne water-soluble monomer(s) contains a hydrophobic liquid, a hydropnobic monomer and an oil-soluble surfactant. The hydrophobic liquids suitable for use herein include benzene, xylene, toluene, mineral oils, kerosenes, petroleuo, and mixtures thereof. A preferred hydrophobic liquid is Isobar M (sold by Humble Oil and Refinery Company). The hydrophobic monomer(s) which may be used in this invention include one or more of vinyl esters, such as vinyl acetate, alkyl acrylates, such as ethylacrylate, alkyl methacrylates such as methyl methacrylate, vinyl ethers such as butylvinyl ether, acrylonitrile, styrene and its derivatlves, such as -methylstyrene, N-vinyl carbazole, and the like. The surfactants suitable for use in this invention are usually of the oil-soluble type having a Hydrophile-Lipophile Balance (HLB) value of from about 1 to about 10, preferably from about 2 to about 6. These surfactants are normally referred to as the water-in-oil type. The surfactants include fatty acid esters1 such as sorbitaii monolaurate, sorbitan monostearate, sorbitan monooleate, sorbtan trioleate, mono and diglycerides, such as mono and diglycerioes obtained from the glycerolysis of edible fats, polyoxyetnylenated fatty acid esters, such as pol yottyethyl enated (4) sorbitan monostearate, pol yoxyethylenated linear alcohol, such as Tergitol 15-S-3 and Tergitol 25-L-3 (both supplied by Union Carbide Corp.), polyoxyethylene sorbitol esters, such as polyoxyethylene sorbitol beeswax derivative, polyoxyethylenated alcohols such as polyoxyethylenated (2) cetyl ether, and the like. The mixture of the aqueous phase and oil phase contains from about 20 to about 50, preferably fran about 22 to about 42 weight percent of the hydrophobic liquid and hydrophobic itonomer(s), based on the total weight of the composition. The aqueous solution (i) containing the water-soluble monomer(s) is combined with the mixture containing a hydrophobic liquid, a hydrophobic mcnsmer(s) and an oil-soluble surfactant. This mixture is homogenized to form a water-in-til emulsion. Homogenization takes place by by subjecting the mixture to high shear mixing techniques which are generally wellknawn in the art. These include the use of harogenizers, high speed mixers and any other techniques for obtaining high shear mixing. The hanogenization is carried out at a temperature of fran about 10 to about 400C, preferably fran about 15 to 250C. The homogenization may be carried out either continuously or in a batch process. The emulsions so prepared have a rather narrow particle size dis tritution. The diameters of the majority of the particles range from about 0.2 to about 5 microns. The water-in-oil emulsion so produced comprises: (a) An aqueous phase constituting fran about 45 to about 80, preferably from about 48 to about 78 weight percent and containing watersoluble monomer(s) wherein the moners constitute fran about 20 to about 60, preferably from about 30 to about 50 weight percent; (b) A hydrophobic liquid and hydrophobic monaner(s) constituting fran about 15 to about 50, preferably fran about 20 to about 40 weight percent; (c) An oil-soluble surfactant constituting from about 0.1 to about 5, preferably fran about 1 to about 3 weight percent. After forming the water-in-oil emulsion, it is generally deoxygenated, by for example, subjecting the emulsion to a vacuum of from about 50 to about 500, preferably fran about 100 to about 200 mn of mercury under an inert gas atmosphere at a temperature of fran about 10 to about 400C, either continuously or as a batch process. A reactor is continuously charged with the decKygenated water-inoil emulsion. Preferably, an initial charge of between about 20 to about 50 percent of the deoxygenated emulsion is added to the reactor. Most preferably, the reactor is charged with an ant of deoxygenated water in-oil emulsion so as to cover the agitator blades therein. The amount charged to the reactor depends on the geatetry and size of the reactor. Also, a catalyst or initiator useful in polymerizing ethylenically unsaturated ncnomers is added to the reactor. These catalysts include one or more azo and/or peroxide containing compounds, such as t-butyl hydroperoxide, t-butyl perbenzoate, benzoyl peroxide, ammonium persulfate, cumene hydroperoxide, 2,2'-azobis(isobutyroni-trile), 2,2'-azobis(2,4-di methyl-valeronitrile), redox catalysts, and others known in the art.Thes catalysts are added to the reactor either directly or in the form of a solution, i.e., the catalyst is dissolved in a solvent, such as a hydrocarbon liquid, i.e., toluene. The catalyst solution contains fran about 1 to about 10, preferably fran about 3 to about 6 weight percent of the catalyst. Fran about 1 to about 99, preferably from about 20 to about 60 percent of the catalyst solution is initially added to the reactor containing the water-in-oil emulsion. The e remaining water-in-oil emulsion and catalyst solution are then continually fed into the reactor. The e polymerization is carried out at a temperature of fran about 30 to about 700C, preferably fran about 40 to about 550C, most preferably fran about 48 to about 520C, for about 1 to about 10 hours, preferably fran about 2 to about 6 hours. The reaction time depending on the size of the reactor and the polymerization conditions. The polymerization is generally carried out at atmospheric pressure, although subatmospheric and superatmospheric pressures may be used. The polymerization is preferably carried out under an inert atmosphere, such as a helium, argon or nitrogen. The polymerization reaction generates considerable heat which must be removed. Generally, the heat is dissipated by normal cooling facilities. The polymerization reaction rate may be controlled by the introduction of small quantities of air (atmospheric air and/or oxygen) into the reaction. The air may be introduced, i.e. sparged, either intermittently or oontinuously into the reactor to control the reaction temperature. When a continuous air sparging is employed, the amount of oxygen in the reaction medium must be carefully controlled so as to achieve the desired rate of polymerization. An oxygen content of from about 0.01 to about 1.0, preferably fran about 0.02 to about 0.50 parts per million is desirable. When the air is introduced intermittently, a flow rate of fran about 0.01 to about 1.0, preferably from about 0.05 to about 0.5 cubic inches per minute, per pound of reactor charge is desirable. The duration of air injection may vary fran a fraction of a second to a few seconds, and it may be repeated as many times as necessary until a desired rate of polymerization is achieved. After the polymerization is complete, an antioxidant may be added to the reaction mass. Any organic antioxidant suitable for the inhibi tion of free radical reactions may be used. The e antioxidant is generally dissolved in a suitable solvent. The preferred antioxidants include substituted phenols, such as Ionol, thiobisphenol, such as Santonox-R, and hydroquinone derivatives, such as the nxtxmethyl ether of hydroquinone. The e suitable solvents include toluene, benzene, xylene, diethyl ether, methyl acetate, and the like. The antioxidant is present in the solution in amounts of fran about 1 to about 30, preferably fran about 5 to about 10 percent. The antioxidant solution is added to the reaction mass in amounts of from about 0.05 to about 5 parts per hundred parts of resin. Addition of the antioxidant may be commenced either at the end of the polymerization or after the reaction mixture has been cooled to am bient temperature. The reaction mass is generally cooled to about 25"C and the poly mer water-in-oil emulsion recovered. The polymer water-in-oil emulsion is described in European Patent Application (Attorney Docket No. SC 13,299-EP) filed in the name of Union Carbide Corporation, titled "Polymer Water-in- Oil -flnulsions", and filed on the same date as this application. The polymer water-in-oil emulsion as described in said Application (Attorney Docket No. SC-13,299-EP) comprises: (a) an aqueous phase comprising fran about 60 to about 80, preferably fran about 68 to about 78 weight percent, and containing therein from about 30 to about 70, preferably from about 35 to about 55 weight percent of polymer and fran about 30 to about 70, preferably fran about 45 to about 65 weight percent of water, based on the total weight of the formulation; (b) a hydrophobic liquid constituting fran about 15 to about 39.5, preferably fran about 19 to about 31 weight percent, and (c) an oil-soluble surfactant constituting fran about 0.5 to about 5, preferably fran about 1 to about 3 weight percent (based on the total weight of the emulsion). The polymers produced by the process of this invention have an intrinsic viscosity of fran about 2 to about 40, preferably fran about 10 to about 35, and most preferably fran about 18 to about 30 dl/g as measured in a one normal (N) aqueous sodium chloride solution at 250C. The polymers produced by the process of this invention are copolymers, terpolymers or tetrapolymers. The polymers may be anionic, cationic or nonionic. The polymers are preferably of the following general formula: EMI9.1 wherein R, R1 and R3 are independently hydrogen or methyl1 R; is an alkali metal ion, such as Na+ or K+, R4 is OR5, where R5 Is an alkyl group having up to 5 carbon atoms, EMI10.1 wherein R is either methyl or ethyl, EMI10.2 phenyl, 7 7 substituted phenyl, CN, or EMI10.3 and R6 Is an alkyl group having up to 8 carbon atoms, wherein(a) is from 0 to about 90, preferably from about 30 to about 60 percent, (b) is from to about 90, preferably from about 30 to about 60 percent, (c) is from about 0.2 to about 20, preferably from about 1 to about 10 percent, with the proviso that (a)+(b)+(c) equal 100, and (d) Is an integer of from about 1,000 to about 500,000. Under certain conditions, the alkoxy or acyloxy groups in the polymer may be partially hydrolyzed to the corresponding alcohol group and yield a tetrapolymer of the following general formula: EMI10.4 wherein R, R1, Rt, R3, R4, a, b, c, and d are as previously defined and e is from about 0.1 to less than about 20 percent; The preferred polymers are terpolymers of the following formula: EMI10.5 wherein R+2 is Na+ Or K+, R7 is methyl, ethyl, or butyl, and f Is from about 5 to about 90, preferably from about 30 to about 60 percent, g is from about 5 to 90, preferably from about 30 to 60 percent h is from about 0.2 to about 20, with the proviso that (f)+(g)+(h) equal 100 and d is as previously defined. The preferred tetrapolymers are of the following formula: EMI11.1 wherein h , R31 R7, f, g, h, d and e are as previous defined. If desired, the polymer may be recovered by, for example, coagulation in a large excess of-a non-solvent for the polymer, sucn as isopropyl alcohol. The polymer is then collected by filtration and subsequently dried. After the water-in-oil emulsion is preparea, a water-soluole inverting surfactant may De aodea thereto. The surfactants whicn may be used include polyoxyetnylene alkyl phenol, polyoxyethylene (10 mole) cetyl ether, polyoxrethylene alkyl-aryl etner, quaternary ammonum derivatives, potassium oleate, N-cetyl N-ethyl morpnolinium ethosulfate, sodium lauryl sulfate, condensation products of higner fatty alconols with ethylene oxide, sucn as tne reaction product of oleyl alcohol with 10 ethylene oxide units; condensation products of alkyiphenols and methylene oxiae, such as tne reaction products of ;sooctylphenol with 12 ethylene oxide units; condensation products of higher fatty acid amines with five, or more, ethylene cxide units; ethylene oxide conden- sat ion products of polyhydric alcohol partial higher fatty esters, and their inner anhydrides (mannitolanhydride, called Mannitan, and sorbitolanhydride, called Sorbitan). The preferred surfactants are ethoxylated nonyl phenols, ethoxylated nonyl phenol formaldehyde resins, and the like. The e inverting surfactant is used in amounts of from about 0.1 to about 20, preferably from about 1 to about 10 parts per one hundred parts of the polymer. The water-in-oil emulsion containing the inverting surfactant is solubilized or inverted in the presence of water. The e polymer-containing emulsion releases the polymer in the water in a very short period of time The solubilized polymer may then be used as a flocculant. For use as a flocculant the water solution contains fran about 0.001 to about 0.3, preferably fran about 0.01 to about 0.1 percent of the polymer. EXAMPLES The following examples serve to give specific illustrations of the practice of this invention but they are not intended in any way to limit the scope of this invention. Example 1 Preparation of monomer emulsion feed: (i) Sodium acrylate solution: An acrylic acid solution containing 158.2 gm of acrylic acid and 186.94 gm of deionized water was neutralized with a freshly prepared 40 percent sodium hydroxide solution (about 229.09 gm) to a final pH of 6.5. The neutralization was carried out at a temperature not exceeding 200C to prevent premature polymeriza tion fran taking place. (ii) Acrylamide solution: The solution was prepared by adding 205.69 gm of acrylamide crystals under vigorous stirring to 251.95 gm of deionized water at a temperature below 250C. Air was present during the dissolution to inhibit polymerization. (iii) Oil-soluble itonater and surfactant mixture: A homogenous solution was prepared by dissolving 18.92 gm of a sorbitan mocoleate (Span-80 supplied by Imperial Chemical Industries) into 339.5 gin of IsoparEM while stirring. Thereafter, 27.27 gin of vinyl acetate was rapidly added and the system stirred for an additional five minutes to yield a uniform mixture. (iv) Monomer emulsion feed: Intro a Waring blender, containing mixutre (iii), was added, under vigorous stirring, solutions (i) and (ii) The latter was combined with 0.06 gm of ethylenediamine tetraacetic acid prior to its addition to ensure compositicnal uniformity of the finished irmer emulsion. The monomer emulsion as prepared above was thoroughly deoxygenated by stirring under a vacuum for 10 minutes and subsequently breaking the vacuum with nitrogen; this procedure was repeated two more times. Thereafter, the monomer emulsion was kept at 250C or below under a nitrogen atmosphere until its complete addition. The storage tank was equipped with a cooling coil (jacket), a temperature measuring device, and an airinjection dip tube which can be used to stop the polymerization in case of an accidental initiation. Initiator solution feed: This solution was prepared by dissolving 0.78 gm of 2,2'-azobis(isobutyronitrile ) dissolved in 17.78 gm of toluene. The solution was purged with nitrogen before and during the course of polymerization. inhibitor solution: The solution was prepared by dissolving 0.78 gra of a thiobisphenol (Santonox-R supplied by Monsanto Chemical Co, ) in 10 gm of toluene. The reactor consisted of a two-liter Pyrex glass reactor equipped with a turbine agitator, two addition tunnels, a condenser, a thermometer and a nitrogen inlet and outlet tube. An external heating/cooling bath was employed. The turbine agitator had a four-one-inch blade impeller and the blades were pitched at a 450 angle to the driving shaft. The reactor was charged, under a nitrogen atmosphere, with 282.32 gm (20 percent) of the nsgumer emulsion. While the nitrogen flow continued, heating was applied to bring the reaction temperature to 550C. Once the temperature was stabilized, 3.91 gm of the initiator solution was quickly added. Thereafter, both the ncncmer emulsion and the catalyst solution streams were continuously fed into the reactor at rates such that feeding was complete in about two hours. The induction time was usually very short and an exothenn may occur jintediately after the initiator addition. After charging was complete, the polymerization was allowed to continue for two additional hours. During this period, sufficient cooling was provided to dissipate the heat of polymerization. The reactor temperature was maintained at 55+20C. At the end of polymerization, the inhibitor solution was added and the reactor was allowed to cool to roan temperature (about 250C). The product was discharged through a two-layer cheese cloth. The conversion was usually quantitative and the finished emulsion contained about 30 percent by weight of polymer. The polymer had an intrinsic viscosity of 18.4 dl/gm. as measured in a one normal aqueous sodium chloride solution. The emulsion was highly uni- form and contained very fine particles which had diameters ranging fran 0.2 to 2 microns. Ecarle 2 Preparation of monomer emulsion feed (i) Sodium acrylate solution: An acrylic acid solution containing 124.84 gm acrylic acid and 227.86 gm of deionized water was neutralized with a freshly prepared 40 percent sodium hydroxide solution (about 173.39 gm) to a final pH of 6.5. The neutralization was carried out at temperatures not exceeding 20"C to prevent premature polymerization fran taking place. (ii) Acrylamide solution: This solution was prepared by adding 205.93 gm of acrylamide crystals to 261.6 gm of water under vigorous stirring at temperatures below 250C. Air was present during the dissolution to inhibit polymerization. (iii) Oil-soluble monomer and surfactant mixture: A homcgenous solution was prepared by dissolving 19.12 gm of Span-80 into 339.43 gm of IsoparEM under agitation. Thereafter, 66.6 gin of ethyl acrylate was rapidly added and the system stirred for an additional five minutes to yield a uniform mixture. The monomer emulsion feed was prepared and deoxygenated, the initiator solution feed and inhibitor solution were prepared and the manomers polymerized all by the procedure as described in Example 1. The product was a milky white water-in-oil emulsion. Examination by an optical microsoope showed that the average diameter of the suspended particles was about 0.2 to 2 microns. The polymer had an intrinsic viscosity of 16.4 dl/gm as measured in a one normal aqueous sodium chloride solution. Example 3 The procedure of Example 1 was exactly repeated except that the 2,2'-azcis (isobutyronitrile) initiator was replaced with the same amount of 2,2-azabis(2r 4-dimethyl-Mleranitrile (Vazo-52 supplied by E.I. duPont de Nemours Co.). A uniform milky white water-in-oil emulsion was prov duced. The average diameter of the suspended particles was measured by an optical microscope and found to be about 1.5 microns. The polymer had an intrinsic viscosity of 18.1 dl/gm as measured in a one normal aqueous sodium chloride solution. Example 4 The procedure of Example lwas exactly repeated except that the 2,21-azobis(isobutyronitrile) initiator was replaced with the same amount of 2, 2-azobis (2, 4dittethyl -valeronitrile) and the polymerization was carried out at a temperature of 43"C instead of 55"C. A uniform, milky white water-in-oil emulsion was produced. The polymer had an intrinsic viscosity of 28.6 dl/gm as measured in a one normal aqueous sodium chloride solution. Example 5 The procedure of Example 4 was exactly repeated except that one-half the amount of initiator was used. The polymer product had an intrinsic viscosity of 29.7 dl/gm as measured in a one normal aqueous sodium chloride solution. Example 6 The proceoure of Example 5 was exactly repeated except that the polymerization was carried out at a temperature of 40iC instead of 43'C. A uniform milKy wnite water-in-oil emulsion was obtained. Tne polymer product had an intrinsic viscosity of 30.6 dl/gm as measured in a one nonnal aqueous sodium chloride solution. Tne suspended particles in tne emulsion were found to have diameters ranging from 0.2 to 2 microns. Example 7 The procedure of Example 1 was exactly repeated except: (a) tne sodium acrylate solution was prepared using 28.22 gm of acrylic acia and 39.2 gm of a 40 percent sodium nydroxide solution and 50 gm of water, (b) the acrylamide solution contained 47.14 ym of acrylamide, 72.75 gm of water, ano 0.02 gin of ethyteneaia ine tetraacetic acid, and (c) the oil mixture was made from 4.4 gm of Span-SO, 82 gm of Isopar-M, and 12.99 gm or vinyl acetate and (a). a mixture containing 0.2 gm of the monomethyl ether of hydoquinone, 3 gm of water, and 2.5 gm of Isopar- was introduced at the end of polymerization to act as an inhibitor. A uniform, milky white emulsion was produced. The conversion was quantitative. Tne recovered polymer was found to contain 12.83 mole percent of vinyl acetate, 52.19 mole percent of acrylamide, and 34.98 mole percent of sodium acrylate. Tne polymer had an intrinsic viscosity of 8.61 dl/gm as measured in a one normal aqueous sodium chloride solution. Example 8 The procedure of Example 1 was exactly repeated except: (a) tne sodium acrylate solution was prepared using 48.34 gm of acrylic acid 61.37 gm of a 40 percent sodium hydroxide solution, and 66.6 gm of water, (D) the acrylamlde solution contained 62.85 gm of acrylamide, 97.15 gm of water, ana 0.02 gm of ethylenediarnine tetraacetic acid, (c) the oil mixture was made from 5.8 gm of Span-80, 113.3 gni of Isopar-M, and 9.5 gm of vinyl acetate and (c) a mixture containing 0.26 gi;i of tne monomethyl ether of hydroquinone, 2.5 gm of water, and 2.5 gm of lsopar-M was introduced at the end of polymerization to act an inhibitor. A uniform, milky.wnite emulsion was produced. Tne recovered polymer was found to contain 10.14 mole percent of vinyl acetate, 55.55 mole percent of acrylamide, ana 35.31 mole percent of sodium acrylate. The polymer had an intrinsic viscosity of 10.67 dilgm as measured in a one normal aqueous sodium chloride solution Example 9 The procedure of Example 2 was exactly repeated except: (a) the pH of the sodium acrylate solution was 9.37 instead of 6.5, (b) the initiator solution was prepared by dissolving 0.39 gm of 2,2'-azobis(2,4-dimetnyl-valeronitrile) in 18.78 gm of toluene and (c) the polymerization was carried out at 40tC, A uniform product was obtained. The recovered polymer had an intrinsic viscosity of 28 al/gm as measured in a one nonnal sodium aqueous chloride solution. Example 10 The procedure of Example 9 was exactly repeated except that tne pH of the sodium acrylate solution was 6.5. A unifonn product was obtained. Tne recoveted.polymer naa an intrinsic viscosity of 24.6 dligm as measured in a one normal aqueous sodium chloride solution. Example 11 The procedure of Example 2 was exactly repeated except: (a) the sodium acrylate solution was adjusted to a pH of 10.67, (b) an equivalent amount of 2,2-azobis (2,4-dimethyl-. valeronitrile) was used instead of 2,21-azobis(isobutyronitrile), and (c) tne polymerization was carried out at a temperature of 43 0C. A uniform water-in-oil emulsion was obtained. The recovered polymer had an intrinsic viscosity of 15.9 dllgm as measured in a one normal aqueous sodium cnlpride solution. Example 12 The procedure of Example 2 was exactly repeatea except: (a) an ammonium persulfate initiator was used in aooition to the 2,2'-azobis(isobutyronitrile), and (b) an aqueous solution containing 0.3 gm of ammonium persulfate ano 3 gm of water was introduced to the reaction vessel one-nour after the completion of the monomer addition. A uniform water-in-oil emulsion was obtained. The recovered polymer had an intrinsic viscosity of 10.34 aligm as measured in a one normal aqueous sodium chloride solution. Example 13 The procedure of Example 12 was exactly repeated except tnat the 2,2'-azobis(isobutyronitrile) was replaced witn an equal amount of lauroyl peroxide. A milky-whlte, uniform emulsion was obtained. The recovered polymer had an intrinsic viscosity of 9.86 dl/gm as measurea in a one normal aqueous sodium chloride solution. Example 14 The procedure of Example 13 was exactly repeated except that the lauroyl peroxide initiator was replaced with an equal amount of bentoyl peroxide. A uniform water-in-oil emulsion was contained. The recovered polymer had an intrinsic viscdsity of 9.85 allgm as measured in a one normal aqueous sodium chloride solution. Example 15 The procedure of Example 1 was exactly repeated except that the Span-80 was replaced with an equal amount of a sorbitan monostearate (Span-6O supplied ny Imperial Chemical Industries). A uniform, milky white emulsion was obtained. Tne recovered polymer had an intrinsic viscosity of 18.1 dl/gm as measureo In a one normal aqueous sodium cntorioe solution. Example 16 The procedure of Example 1 was exactly repeated except that the Span-80 was replaced with an equal amount of an 1:1 mixture of a sorbitol partial fatty esters (Atpet-lOO suppliea by Imperial Chemical Inaustries) and a sorbfran tristearate (Span-65 suppliea by Imperial Chemical Industries). A uniform, milky white emulsion was obtained. The recovered polymer had an intrinsic viscosity of 17.9 dligin as measured in a one normal aqueous sodium chloride solution. Example 17 The procedure of Example 1 was exactly repeatea, except that the Span-80 was replaced witfl an equal amount of a polyoxyethylene sorbitol beeswax derivative (G-1702 supplied by Imperial Chemical Industries). A uniform, milky white emulsion was obtained. The recovered polymer had an intrinsic viscosity of 17.6 dllgm as measured in a one nonnal aqueous sodium chloride solution. Example 18 A portion of the product preparea in Example 1 was tnorougnly mixed with a water soluble surfactant, i.e., a polyoxyethylenatea nonylpnenol (Tergitol SP-10 supplied by Union Carbide Corporation) to yield an emulsion containing about 1.5 percent by weight of the surfactant. This mixture can be rapidly dissolved in water with stirring. An aqueous solution containing 0.3 percent of this polymer nad a typical Brookfiela viscosity to about 2,400 centipoise (Brookfield Viscometer Moael HdT, Spindle No. 2, 10 RPM and at 25 0C.). Example 19 A portion of the product made in Example 2 was mixed with a water soluble surfactant, i.e., a polyoxyethylenated nonylphenol (Tergitol NP 13 supplied oy Union Carbioe Corporation) to yield an emulsion containing about 1.5 percent by weight of the surfactant. An aqueous solution containing 1 percent by weight of this emulsion had a Brookfield viscosity of about 2,200 centlpoise (as measured by the procedure in Example 18). Example 20 The procedure of Example 1 was exactly repeated except: (a) tne acrylamide solution was prepared using a coitizercial 50 percent aqueous solution (Acrylamiae-50 supplied by American Cyanamide) instead of the acrylamide crystals (b) ana one half tne amount of 2,2'-azobis (2,4-dimethyi-valeronitrile) was substituted for the 292|-dzobis(isobutyronitrile). A uniform and milky white emulsion was obtained. Tne recovered polymer had an intrinsic viscosity of 14.3 dl!gm as measured in a one normal aqueous sodium cnloride solution. Example 21 Tne procedure of Example 1 was exactly repeated except: (a) the acrylamide solution was prepared using acrylamide-50 (described in Example 20), (b) an equal amount of 2,2'-azobis (2,4-dimethyl-valeronitrile) was substituted for the 2,2'-azobis(isobutyronftrile), (c) a douole amount of ethylenediamine tetraacetic acid was used, and (d) the polymerization was carried out at a temperature or 52' instead of 55' C. A fine emulsion was obtained at the ena of polymerization. The recovered polymer had an intrinsic viscosity of 19.1 dilym as measured in a one normal aqueous soaium cnloride solution A 0.3 percent aqueous solution of this polymer had a Brookfield viscosity of 2,912 centipoise (Brookfiela Viscometer Model HBT, Spindle No. 2, 10 RPM at 25'C). Example 22 A (vinyl acetate-sodium acrylate) copolymer water-in-oil emulsion was prepared according to the following procecures: An aqueous solution was prepared by mixing, under cooling conditions, 96.49 gm of acrylic acid, 163.75 gm of water, 130 gm of a 40 percent sodium hydroxide solution and 0.02 gm of ethylenedlamine tetraacetic acid. Separately, an oil solution was prepared by mixing 5.8 gm of Span-0, 113.3gm of Isopar-e and 6.5 gm of vinyl acetate. Tne two solutions were combined in a nigh speed waring blender to give a uniform emulsion. A catalyst solution was prepared by dissolving 0.26 gm of 2,2'-azobis(isobutyronitrile) it 3.13 ml of acetone. The monomer emulsion was tnen deoxygenated as described in Example 1. The polymerization was carried out in the manner as in Example 1, except tnat a one-liter pyrex ylass reactor equipped as described in Example 1, was used. Tne product produced was a milKy white emulsion containiny about 24 percent by weight of the polymer. Tne polymer nad an intrinsic viscosity of 4.2 dl/gm as measureo in a one normal aqueous sodium chloride solution. Example 23 A nonionic vinyl acetate-acrylamide copolymer was prepared according to tne procedure as aescribed in Example 22, except that the aqueous solution contained 125.96 gm of acrylamide, 200.57 gm of water and 0.02 gm of ethylenediamine tetraacetic acid. The water-in-oil emulsion contained 26 percent by weight of active polymer. The polymer had an intrinsic viscosity of 3 dl/ym as measured in a one normal aqueous sodium chloride solution. Example 24 A cationic copolymer composed of tne quaternization product of methylaininoethyl methacrylate, methyl chloriae and hydroxyethyl acrylate was prepared according to the procedure as described in Example 22, except that the aqueous solution was made from 146.95 gm of the quaternization product, 332.6 gm of water and 0.02 gm of ethylenediamine tetraacetic acid. Tne oil phase was composed of a fine mixture of 146.93 ym of lsopar-M, 5.8 gm of Span-80, and 20 gm of hyaroxyethyl acrylate. After the polymerization was completed, a fine ana uniform emulsion was recovered. The polymer had an intrinsic viscosity of 6.1 dllgm as measured in a 3 percent sodium cnloride solution. Example 25 A cationic terpolymer composed of tne quaternization product used in Example 24, acrylamioe, ana vinyl acetate prepared according to the procedure described in Example 22, except that the aqueous solution was maae from 35.5 gm of acrylamide, 332.6 gm of water, 0.02 gm of etnylenediamine tetraacetic acid ana 138.4 gm of tne quaternization product. The oil solution was made from 5.8 gm of Span-80, 113.3 gm of Isopar-M and 5 gm of vinyl acetate. The finished water-in-oil emulsion contained aoout 20 percent by weight of active polymer.The polymer had an intrinsic viscosity of 6.1 dllgm as measured in a 3 percent aqueous sodium chloride solution. Example 26 Tne procedure of Example 1 was exactly repeated with the exception that tne deoxygenatlon of the monomer emulsion was performed by a continous process aescribed as follows: The monomer emulsion prepared according to Example l(iv) was pumped through a thin-film devolatilizer operating under a vacuum of 200 rtrn of mercury pressure and a nitrogen atinosphere. The operating conditions of the thin-film devolatilizer were adjusted such that the dissolved oxygen content in the deoxygenated monomer emulsion was reduced to below 3 ppm, preferably below 1 ppm. The reactor was charged, under a nitrogen atmosphere, with 282.32 gm (20 percent) of the deoxygenated monomer emulsion. while the nitrogen flow continued, tne reaction temperature was raised to 55 . Once the temperature was stabilized, 3.91 gm of tne initiator solution was added. Tne monomer emulsion was then addea continously through the thin-film devolatilizer into the reactor at a rate such that the addition was complete in about two hours. The rest of the initiator solution was fea simultaneously as described in Example 1. After charging was complete, the polymerization was allowed to continue for two additional hours. At tne end of the polymerization, tne inhibitor solution was added and tne reactor was allowed;to cool to room temperature (about 25 cm. A fine and uniform water-in-oil emulsion was obtained. Tne conversion was greater than 99 percent and the recovered polymer had an intrinsic viscosity of 19.2 ol/Qm as measured in a one normal aqueous sodium chloride solution.

Claims: CLAIMS: 1. A semi-continuous process for producing a polymer water-in-oil emulsion, which process comprises: (a) combining: (i) an aqueous solution comprising at least one water-soluble monomer and (ii) a mixture com- prising a hydrophobic liquid, a hydrophobic monomer and an oil-soluble surfactant; (b) homogenizing the mixture from (a)to form a water-in-oil emulsion; (c) deoxygenating said homogenized water-in-oil emulsion; (d) continually adding the homogenized water-in-oil emulsion to a reactor while adding thereto a deoxygenated initiator solution; (e) heating the mixture from (d) under polymerization conditions so as to form a polymer water-in-oil emulsion, and (f) recovering a polymer water-in-oil emulsion. 2. A process as defined in claim 1 wherein the water soluble monomer in (a) (i) is selected from one or more of the following: acrylamide, methacrylamide, acrylic acid, methacrylic acid, and their alkali metal salts, aminoalkyl -acrylate, aminoalkyl methacrylate, dialkylaminoalkyl acrylate, dialkylamino methacrylate, and their quarternized salt with dimethyl sulfate or methyl chloride, vinyl benzyl dimethyl ammonium chloride, alkali metal and ammonium salts of 2-sulfoethylacrylate, alkali metal and ammonium salts of vinyl benzyl, sulfonates, and maleic anhydride and 2-acry - amido-2-methylpropane sulfonic acid. 3. A process as defined in claims 1 or 2 wherein the water soluble monomer in (a) (i) is selected from acrylamide or acrylic acid, or mixtures thereof, and alkali metal salts of acrylic acid. 4. A process as defined in any of claims 1-3 wherein the aqueous solution in (a) (i) contains from about 45 to about 80 percent of a combination of water and water soluble monomer(s). 5. A process as defined in any of claims 1-4 wherein the hydrophobic monomer in (a) (ii) is selected from a vinyl ester, an alkyl acrylate, an alkyl methacrylate, a vinyl ether, acrylonitrile, styrene and its derivatives, N-vinyl carbazole, an alkyl vinyl ether, and mixtures thereof, preferably from vinyl acetate, ethylacrylate, butylvinyl ether, acrylonitrile, styrene, d-methylstyrene, N-vinyl carbazole, and mixtures thereof. 6. A process as defined in any of claims 1-5 wherein the hydrophobic liquid is selected from benzene, xylene, mineral oil, kerosene, petrolewnoil, and mixtures thereof, and preferably is Isopar M. 7. A process as defined in any of claims 1-6 wherein the oil-soluble surfactant has an HLB of from about 1 to about 10. 8. A process as defined in any of claims 1-7 wherein the mixture of (a) contains from about 15 to about 50 percent of the hydrophobic liquid and hydrophobic monomer(s). 9. A process as defined in any of claims 1-8 wherein the homogenization of (b) is carried out at a temperature of from about 10 to about 400C. 10. A process as defined in any of claims 1-9 wherein the water-in-oil emulsion has particles whose diameters are from about 0.2 to about 5 microns. 11. A process as defined in any of claims 1-10 wherein the homogenized water-in-oil emulsion is deoxygenated in step (c) by subjecting it to a vacuum and/or nitrogen sparging. 12. A process as defined in any of claims 1-11 wherein the polymerization is carried out at a temperature of from about 30 to about 700C. 13. A process as defined in any of claims 1-12 wherein the polymerization reaction rate is controlled by the introduction of air into the reaction. 14. A process as defined in any of claims 1-13 wherein an antioxidant is added to the reaction mass after polymerization. 15. A process as defined in any of claims 1-14 wherein the polymer in the water-in-oil emulsion has an intrinsic viscosity of from about 2 to about 40 dl/gm as measured in an one normal aqueous sodium chloride solution at 250C. 16. A process as defined in any of claims 1-15 wherein the polymer is a copolymer, terpolymer or tetrapolymer. 17. A process as defined in any of claims 1-16 wherein the polymers are of the following general formula: EMI28.1 wherein R, R1 and R3 are independently hydrogen or methyl, is is an alkali metal ion, R4 is OR5, where R5 2 is an alkyl group having up to 5 carbon atoms, EMI29.1 wherein R7 is either methyl or ethyl, EMI29.2 phenyl or substituted phenyl, CN, or EMI29.3 and R6 is an alkyl group having up to 8 carbon atoms, and wherein (a) is from 0 to about 90, (b) is from 0 to about 90 (c) is from about 0.2 to about 20, with the proviso that (a)+(b)+(c) equal 100, and (d) is an integer of from about 1,000 to about 500,000. 18. A process as defined in any of claims 1-16 wherein the polymer is a terpolymer of the following formula: EMI29.4 wherein R2+ is Na+ or K+ , R7 is methyl, ethyl, or butyl, and f is from about 5 to about 90 percent, g is from about 5 to about 90, h is from about 0.2 to about 20 with the proviso that (f)+(g)+(h) equal 100 and d is an integer of from about 1000 to about 500,000.

Inventors: BRODE, GEORGE LEWIS, FAN, YOU-LING
Applicants: UNION CARBIDE CORPORATION
Application year: 1982
Main classification: C08F2
IPC codes: C08F2