Microemulsified functionalized polymers

Abstract: Functionalized polymer microparticles having particle diameters of from about 200 to about 4000Å are prepared and are useful in facilitating a variety of flocculation and thickening of dispersions of suspended solids applications.

Description: The present invention relates to a method of dewatering suspended solids using functionalized, water-soluble polymer microparticles. Functionalized, water-soluble polymers are well known in the art and are useful in a variety of applications. A major drawback of many functionalized polymers is their tendency to cross-link, this problem becoming more severe as the polymer solids content or the molecular weights thereof is increased. Attempts to reduce the tendency of such polymers to cross-link have proven less than satisfactory. For example, high molecular weight Mannich acrylamide polymers (PAMS) are well known and are used in a variety of flocculant applications. A major drawback of Mannich PAMS is their tendency to cross-link. This problem becomes more severe as the polymer solids are increased. Consequently, these polymers are generally made as dilute aqueous solutions in an attempt to slow down the rate of interpolymer cross-linking. The solids level must also be kept low, particularly for very high molecular weight Mannich PAMS, owing to the ability of these polymers to viscosity water. As a result, solids levels of very high molecular weight Mannich PAMS must generally be well below 10%, and more typically 6% or less so that the solutions can be pumped and handled conveniently. Several approaches have been tried to overcome these problems. One approach has been to make the Mannich PAMS at the site of use by inverting high solids inverse emulsion PAMS in water containing dialkylamines and formaldehyde. USP 4,021,394 and USP 4,022,741 describe continuous processes for the preparation of Mannich PAMS which entails inverting an inverse emulsion PAM in a process stream containing formaldehyde and a secondary amine and subjecting the stream to turbulence by in-line mixing to produce an 1-15% aqueous solution of Mannich PAM. This approach, however, suffers from the need to store multiple chemicals on site and from the problems inherent in running chemical reactions at such locations. Another approach has been to prepare dry Mannich PAMS, as described in U.S. 3,864,312; U.S. 3,539,535 and U.S. 3,790,529, or blends of dry PAMS with dry, low-molecular weight Mannich-base forming compounds which, when dissolved in water, react to produce Mannich PAMS, as described in EPO 210,784. These approaches, in general, suffer from cross-linking problems, the reversibility of the Mannich reaction, the difficulty and length of time required to dissolve high molecular weight polymers, and other problems. Another approach has been to make the Mannich PAM in inverse emulsions, such as described in U.S. 3,979,348 and U.S. 4,093,542 and U.S. 4,010,131. While this approach produces a product with substantially higher solids, the average particle size thereof ranges from 10,000-20,000Å in diameter, and consequently, cross-linking of the thousands of polymer chains in each particle renders the products ineffective. The cross-linking rate can be reduce somewhat by adding fairly large quantities of stabilizers such as described in U.S. 4,113,685 and U.S. 4,073,763, but cross-linking continues and the products thus possess a very limited shelf life. In our European Patent No. 0374478 (Application No. 89121217.7) from which the present application has been divided, we describe and claim, inter alia, Mannich (alk)acrylamide based polymers which can be prepared at high solids levels or at high molecular weight without extensive interpolymer crosslinking such that they may be economically transported and easily handled by the end user without the need for any on site preparation. Such functionalised polymers are useful for use in methods of dewatering suspended solids and as such satisfy a long felt need in the art. The present invention is directed to the use of such polymers in methods of dewatering suspended solids. In accordance with the present invention there is provided a method of dewatering suspended solids by the addition to said suspended solids of a Mannich (alk)acrylamide-based polymer, comprising preparing said polymer in the form of micelles having particle diameters of 20 to 400 nm (200 to 4000 Å), said micelles being obtainable from a microemulsion. The present invention also provides a method of dewatering suspended solids by the addition to said suspended solids of a Mannich (alk)acrylamide-based polymer, wherein said polymer is in the form of micelles obtained from a microemulsion, and wherein the micelles have particle diameters of from 20 to 400 nm (200 to 4000 Å). In contrast to prior art wherein the functionalised polymers contain large quantities of polymer molecules in the same aqueous environment, the Mannich (alk)acrylamide-based polymers used in the present invention are isolated as individual, or a limited number of polymer molecules in each aqueous emulsion micelle. Thus, the problem of large scale interpolymer crosslinking inherent in the solution and inverse emulsion products of the prior art is overcome, resulting in polymers which, even though crosslinked, are useful for their intended purpose in dewatering suspended solids. The Mannich groups possessed by the (alk)acrylamide polymer particles used in the present invention may be imparted thereto by (1) reacting a water-soluble (alk)acrylamide polymer with a formaldehyde and a secondary amine or a complex thereof, (2) polymerizing an (alk)acrylamide monomer capable of forming a water-soluble polymer in the presence of a formaldehyde and a secondary amine or a complex thereof, or (3) polymerizing an (alk)acrylamide monomer already possessing a Mannich group and capable of forming, alone or in conjunction with another monomer, a water-soluble polymer; or (4) polymerizing an (alk)acrylamide monomer containing a group capable of being transformed into a Mannich group and capable of forming a water-soluble polymer, (1) alone or in conjunction with another monomer, or (2) after said group has been transformed into a Mannich group. More particularly, in one embodiment, the micelles are formed by: (a) admixing (i) an aqueous solution of at least one (alk)acrylamide monomer and optionally, at least one ethylenically unsaturated comonomer; (ii) an oil solution comprising at least one hydrocarbon liquid; and (iii) an effective amount of surfactant or surfactant mixture so as to form an inverse microemulsion; and (b) subjecting the inverse microemulsion obtained in step (a) to polymerization conditions; (c) reacting the polymerized polymer obtained in step (b) with an effective amount of a formaldehyde and a secondary amine or a complex thereof; and (d) optionally, quaternizing the resultant polymer. In a second embodiment, the micelles are formed by: (a) admixing (i) an aqueous solution comprising an (alk)acrylamide monomer, a formaldehyde and a secondary amine or complex thereof and, optionally, at least one ethylenically unsaturated comonomer; (ii) an oil solution comprising at least one hydrocarbon liquid; and (iii) an effective amount of a surfactant or surfactant mixture, so as to form an inverse microemulsion; and (b) subjecting the inverse microemulsion obtained in step (a) to polymerization conditions and allowing the formaldehyde and secondary amine to react with (alk)acrylamide amide groups; and (c) optionally, quaternizing the resultant polymer. In a third embodiment, the micelles are formed by: (a) reacting (i) at least one (alk)acrylamide monomer and, optionally, at least one ethylenically unsaturated comonomer; and (ii) a formaldehyde and a secondary amine or a complex thereof in aqueous solution to produce a Mannich (alk)acrylamide monomer; (b) admixing (i) an aqueous solution of at least one (alk)acrylamide monomer and optional comonomer obtained in (a); (ii) an oil solution comprising at least one hydrocarbon liquid; and (iii) an effective amount of surfactant or surfactant mixture so as to form an inverse microemulsion; (c) subjecting the inverse microemulsion obtained in step (b) to polymerization conditions; and (d) optionally, quaternizing the resultant polymer. Polymerization is carried out by the addition of a polymerization initiator or by subjecting the inverse microemulsion to ultraviolet irradiation. The preparation of functionalised, water-soluble polymers in small aqueous inverse microemulsion droplets or micelles eliminates large scale interpolymer crosslinking problems inherent in larger particle inverse emulsion systems and solution product forms thereby allowing the polymer to maintain dewatering performance on crosslinking and to be prepared at high polymer solids content. As mentioned above, for use herein the micelles have particle diameters ranging from 20 to 400 nm (200 to 4000 Å), preferably from 30 to 200 nm (300 to 2000 Å) and even more preferably from 35 to 100 nm (350 to 1000 Å). (Alk)acrylamide polymers which may comprise the basis for the polymer particles used in the present invention are those which are capable of forming Mannich polymers. Examples of suitable water-soluble (alk)acrylamide polymers include those produced from such monomers as the acrylamides such as acrylamide and methacrylamide and N-alkyl acrylamide such as N-methylacrylamide and N-octylacrylamide. These water-soluble polymers may be prepared, via known polymerization procedures, by polymerization of the above-enumerated monomers, alone or in conjunction with up to about 99.5%, by weight, based on the total weight of the polymer, of additional non-ionic, cationic or anionic comonomers such as acryloylmorpholine; N-vinyl pyrrolidone; N-vinylformamide; the N,N-dialkylacrylamides such as N,N-dimethylacrylamide, N,N-dipropylacrylamide; the N,N-dialkylalkacrylamide such as N,N-dimethylmethacrylamide, N,N-dipropylmethacrylamide; diallyldialkyl ammonium chlorides; the salts and quaternaries of N,N-dialkylaminoalkyl(alk)acrylates, N,N-dialkylaminoalkyl(alk)acrylamides etc; acrylic acid; methacrylic acid; fumaric acid; itaconic acid; maleic acid; 2-acrylamido-2-methylpropanesulfonic acid; styrene sulfonic acid and their salts. Up to about 10%, by weight, same basis, of water-insoluble comonomers may also be included in the base polymers discussed above. Such monomers include styrene; acrylonitrile; methyl acrylate; methyl methacrylate and vinyl acetate. In the dewatering method of the present invention the Mannich (alk)acrylamide-based polymer can be employed as dilute aqueous solutions formed by inverting the emulsions, optionally in the presence of a breaker surfactant, or by recovering the polymer particles from the emulsion such as by stripping or by adding the emulsion to a solvent which precipitates the polymer, e.g. isopropanol, filtering off the resultant solids, drying and redispersing in water. Polymerization in microemulsion and inverse microemulsions is known to those skilled in this art. P. Speiser reported in 1976 and 1977 a process for making spherical "nanoparticles" with diameters less than 80 nm (800Å) by (1) solubilizing monomers such as acrylamide and methylenebisacrylamide and other materials, such as drugs, in micelles and (2) polymerizing the monomers; see, J. Pharm. Sa., 65 (12), 1763 (1976) and U.S. 4,021,364. Both water-in-oil and oil-in-water systems can be used to prepare these nanoparticles. While not specifically called microemulsion polymerization by the author, this process does contain all the features which are currently used to define microemulsion polymerization. These reports also constitute the first examples of polymerization of acrylamide in a microemulsion. Since then numerous publications reporting polymerization of water-soluble polymers in the inverse phase of microemulsions have appeared. See, for example, U.S. Pat. Nos. 4,521,317; 4,681,912 and GB 216149A. In general, microemulsion polymerization processes are conducted by (i) preparing a monomer microemulsion by mixing an aqueous solution of monomers with a hydrocarbon liquid containing an appropriate surfactant or surfactant mixture to form an inverse microemulsion consisting of small aqueous monomer droplets dispersed in the continuous oil phase and (ii) subjecting the monomer microemulsion to free radical polymerization. In order to obtain an inverse microemulsion, it is generally necessary to use particular conditions whose main parameters are as follows: surfactant concentration, HLB of surfactant or surfactant mixture, temperature, nature of the organic phase and composition of the aqueous phase. Suitable monomers are anionic, non-ionic and cationic and are as defined above. The aqueous monomer solution may contain such conventional additives as are desired. For example, the solution may contain chelating agents to remove polymerization inhibitors, chain-transfer agents, pH adjusters, initiators and other conventional additives. Essential to the formation of the microemulsion which may be defined as a transparent and thermodynamically stable emulsion comprising two liquids insoluble in each other and a surfactant, in which the micelles are usually 100 nm (1000Å) or less in diameter, is the selection of appropriate organic phase and surfactant. The selection of the organic phase has a substantial effect on the minimum surfactant concentration necessary to obtain the inverse microemulsion and may consist of a hydrocarbon or hydrocarbon mixture. Isoparaffinic hydrocarbons or mixtures thereof are the most desirable in order to obtain inexpensive formulations. Typically the organic phase will comprise mineral oil, toluene, fuel oil, kerosene, odorless mineral spirits, mixtures of any of the foregoing. The ratio by weight of the amounts of aqueous phase and hydrocarbon phase is chosen as high as possible, so as to obtain, after polymerization, a microemulsion of high polymer content. Practically, this ratio may range, for example, from about 0.5 to about 3:1, and usually approximates 1:1. The one or more surfactants are selected in order to obtain an HLB (Hydrophilic Lipophilic Balance) value ranging from about 8 to about 12. Outside this range, formation of inverse microemulsions generally cannot be attained. In addition to the appropriate HLB value, the concentration of surfactant must be optimized, i.e., sufficient to form inverse microemulsion. Too low a concentration of surfactant leads to the formation of inverse emulsions and too high a concentration results in increased costs and does not impart any significant benefit. Typical surfactants useful in the practice of this invention may be anionic, cationic or nonionic. Preferred surfactants include sorbitan monooleate, polyoxyethylene (20) sorbitan monooleate, sodium dioctylsulfosuccinate, oleamidopropyldimethylamine and sodium isostearyl-2-lactate. Polymerization of the microemulsion may be carried out in any manner known to those skilled in the art. Initiation may be effected with a variety of thermal and redox free-radical initiators including peroxides such as t-butyl peroxide; azo compounds such as azobisisobutyronitrile; organic compound such as, potassium persulfate and redox couples such as ferrous ammonium sulfate/ammonium persulfate. Polymerization may also be effected by a photochemical irradiation processes such as ultraviolet irradiation or by ionizing radiation with a cobalt 60 source. The invention is illustrated by the Examples which follow. Bulk Viscosity (BV) of emulsions is measured at 25±1° in a Brook viscometer (LVT model) with a #2 spindle at 12 rpm. Standard viscosity (SV) is measured by adding 50 gms of a 0.2% aqueous polymer solution and 5.84 gms of sodium chloride to 48 gm of water, stirring the resulting mixture for 5 minutes to completely dissolve the salt, adjusting the pH to 5 and determining the viscosity at 25±0.1°C using a Brookfiled viscometer (LVT model) with UL adapter at 60 rpm. Cationic equivalent (CEQ) is measured by the technique described in J.CHem. Ed., 62 (7), 627 (1985). EXAMPLE 1 Microemulsion Preparation 100 gms of an aqueous solution (pH = 3.5) containing 42.3 gms of acrylamide and 0.02 gm of 2-hydroxyethyl ethylenediaminetriacetic acid are pumped at the rate of 4.4 ml/min into 150 gms of an organic solution containing 128.5 gms of an isoparaffinic solvent having a b. p. of 207-254°C (IPS), 21.9 gms of polyoxyethylenesorbitol hexaoleate (PESH) and 7.8 gms of sorbitan sesquioleate (SS). A clear, monomer containing microemulsion is obtained. 0.0424 gms of 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile in 2 mls of ethyl acetate is added to the monomer containing microemulsion which was previously sparged for 40 minutes using nitrogen. Polymerization is conducted at 30°C. The product is a clear, stable polyacrylamide (PAM) microemulsion (S.V. = 3.8 mPa·s (= 3.8 cps). DMAM Preparation N,N-dimethyaminomethanol (DMAM) is prepared by slowly adding 7.7 gms of 95 percent paraformaldehyde to a 100 ml flask containing 27.50 gms of a 55 percent aqueous solution of dimethylamine and 6.60 gas of deionized water, keeping the exotherm below 45°C. The resultant DMAM solution is then filtered yielding a clear solution possessing 53.20 gms of DMAM solids. Mannich PAM Microemulsion Preparation 30.0 gms of the above PAM microemulsion are placed in a suitable reactor. The emulsion is warmed to 30°C. Next 10.0 gms or the DMAM solution prepared above are added to the PAM microemulsion at a rate of 0.08 ml/min. with gentle stirring. The resulting Mannich PAM microemulsion is stored at ambient temperature until use. After 24 hours, the polymer has a CEQ of 5.75 meq/g and S.V. of 2.5 mPa·s (2.5 cps). Free-Drainage Testing The efficiency of dewatering a typical municipal sludge is determined as follows: 200 gms of sludge are carefully weighed into screw cap jars. Aqueous solutions of Mannich PAM flocculants are prepared by adding the microemulsion (or in the comparative examples, a solution of commercial Mannich PAM) to water so that the polymer concentration is 0.2 weight percent. Various doses of the polymer solutions are added to the sludge samples, water is added to bring the total weight to 250 gms, the mixtures are agitated for 90 seconds, the resulting flocculated sludge is poured into a Buchner funnel containing a filter cloth, and the free drainage is determined by measuring the volume of filtrate collected in 10 seconds. The results are set forth in Table 6, below. MANNICH PAM OF EXAMPLE NO. DOSE (ml) FILTRATE (ml) 1 10 100 12.5 152 15 158 17.5 160 20 140 1 10 60 12.5 120 15 140 17.5 160 20 128 Table 1 clearly shows the superior performance of the Mannich PAM microemulsion of Example 1 as compared to a typical, commercially available, solution Mannich PAM. EXAMPLES 2-7 Examples 2-7 describe the preparation of PAM microemulsions which are used for the preparation of a series of Mannich PAM microemulsions. EXAMPLE 2 To 150 gms of an organic solution containing 128.5g of IPS, 21.9 gms of PESH and 7.8 gms of SS are slowly added 100 gms of a pH 3.5 aqueous solution containing 42.3g of acrylamide and 0.02 gm of N-(2-hydroxyethyl)ethylenediaminetriacetic acid with stirring. The resulting clear, monomer microemulsion is sparged for 40 minutes with nitrogen. 0.0424 gm of 2,2'-azobis-4-methoxy-2,4 dimethylvaleronitrile in 2 mls of ethyl acetate is then added and the microemulsion polymerized at 30°C. The resulting product is a clear, stable PAM microemulsion having a Standard Viscosity (S.V.) of 3.8 cps and a particle size average of 65 nm (650Å) (median value as measured by transmission electron microscopy). EXAMPLE 3 The procedure of Example 2 is again followed and produces a polyacrylamide microemulsion with an S.V. of 3.7 mPa·s (3.7 cps). EXAMPLES 4 - 6 The procedure of Example 2 is used to prepare the PAM microemulsions of Examples 4 - 6 with the exception that the amount of emulsifier is altered as shown in Table 2, below, to vary the resultant PAM microemulsion particle size. PAM MICROEMULSION PESH-g SS-g PARTICLE nm SIZE (Å) mPa·s (cps) Example 4 18.72 6.66 59 (590) 3.7 Example 5 15.60 5.55 71 (710) 3.5 Example 6 12.48 4.44 96 (960) 3.6 EXAMPLE 7 Example 7 shows the preparation of a PAM microemulsion with a different emulsifier system. To 145 gms of an organic solution containing 120 gms of IPS, 14.82 gms of PESH and 11.12 gms of the reaction product of diethanolamine and oleic acid (DOA) are slowly added 100 gms of a pH 3.5 aqueous solution containing 42.3 gms of acrylamide and 0.02 gm of N-(2-hydroxyethyl)-ethylenediaminetriacetic acid with stirring. The resulting clear, monomer containing microemulsion is sparged for 40 minutes with nitrogen. 0.0423 gm of 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile in 2 mls of ethyl acetate are then added and the microemulsion is polymerized at 30°C. The resulting product is a clear, stable PAM microemulsion having an S.V. of 3.1 mPa·s (3.1 cps). EXAMPLE 8 Example 8 describes the preparation of dimethylamine/formaldehyde (DMA/CH 2 O) adducts used to prepare Mannich PAM microemulsions from the PAM microemulsions of Examples 2, 3, and 7. A. 10.08 gms of 95 percent paraformaldehyde are slowly added to a reaction vessel containing 26.3 gms of a 55 percent aqueous solution of dimethylamine keeping the exotherm below 45°C. The resulting solution is filtered yielding a clear solution. B. To 30.0 gms of the solution prepared in Example 8A are added 3.05 gms of 100 percent dimethylamine with mixing, bringing the DMA/CH 2 O ratio from 1/1 to 1.25/1. EXAMPLES 9-15 Examples 9-15 describe the preparation of Mannich PAM microemulsions with differing amounts of dimethylaminomethyl substitution from the PAM microemulsions of Examples 2, 3 and 6 and the DMA/CH 2 O adduct from Example 8B. 30.0 gms of the PAM microemulsion from Example 2 are placed in a reaction vessel at ambient temperature. To this are slowly added 11.0 gms of the DMA/CH 2 O adduct from Example 8B, with stirring, yielding a clear, Mannich PAM microemulsion. After approximately 24 hours, the microemulsion is inverted into water resulting in a Mannich PAM with an S.V. of 3.9 mPa·s (3.9 cps) and a CEQ of 6.2 meq/g. The identical procedure is used to prepare the Mannich PAM microemulsions of Examples 10-15, which differ only in the amount of DMA/CH 2 O adduct charged and the PAM microemulsion, as shown in Table 3. EXAMPLE DMA/CH 2 O adduct(g) PAM MICROEMULSION OF EXAMPLE NO. CEQ (meq/g) S.V. mPa·s (cps) 9 11.0 Ex. 2 6.2 3.9 (3.9) 10 6.6 Ex. 2 3.5 4.8 (4.8) 11 4.4 Ex. 2 3.3 4.6 (4.6) 12 2.2 Ex. 2 - 4.1 (4.1) 13 1.1 Ex. 3 - 2.7 (2.7) 14 1.5 Ex. 3 - 2.7 (2.7) 15 11.0 Ex. 3 - 4.1 (4.1) EXAMPLE 16 Example 16 is a repeat of Example 8A, with the exception being a slight dilution of the clear solution to reduce the adduct concentration. 22.3 gms of 95 percent paraformaldehyde are slowly added to a vessel containing 57.78 gms of a 55 percent aqueous solution of dimethylamine keeping the exotherm below 45°C. The resulting solution is filtered yielding a clear solution. 12.30 gms of deionized water are then added. EXAMPLES 17 - 19 Examples 17-19 describe the preparation of Mannich PAM microemulsions from PAM microemulsions of Examples 2, 6 and 7 and with a DMA/CH 2 O (1/1) adduct. EXAMPLE 17 30.0 gms of the PAM microemulsion from Example 2 are placed in a vessel at ambient temperature. To this are slowly added 10.0 gms of the DMA/CH 2 O adduct of Example 16 with stirring, yielding a Mannich PAM microemulsion. After approximately 24 hours, the microemulsion is inverted into water resulting in a Mannich PAM solution with an S.V. of 3.7 mPa·s (3.7 cps) and a CEQ of 5.6 meq/g. The identical procedure is used to prepare the Mannich PAM microemulsions of Examples 18 and 19 as shown in Table 4, except different PAM microemulsions are used. PAM MICROEMULSION OF EXAMPLE DMA/CH 2 O adduct(g) EXAMPLE NO. CEQ(meq/g) S.V. mPa·s (cps) 18 10.0 Ex. 7 5.1 2.4 (2.4) 19 10.0 Ex. 6 5.4 3.3 (3.3) EXAMPLE 20 Example 20 describes the preparation of PAM microemulsion via redox initiation. To 149.64 gms of an organic solution containing 128.5 gms of IPS, 21.9 gms of PESH and 7.8 gms of SS are slowly added 100 gms of a pH 3.0 aqueous solution containing 42.3 gms of acrylamide, 0.00428 gm of sodium bromate and 0.02 gm of N-(2-hydroxyethyl)-ethylenediaminetriacetic acid with stirring. The resulting clear, monomer microemulsion is sparged for 40 minutes with nitrogen. SO 2 gas is then bubbled into the microemulsion while holding the polymerization temperature at 25°C. The resulting product is a clear, stable PAM microemulsion having an S.V. of 2.1 mPa·s (2.1 cps). EXAMPLES 21 - 22 Examples 21 and 22 show the preparation of a morpholine/formaldehyde adduct and the Mannich PAM microemulsion prepared from this adduct. EXAMPLE 21 10.08 gms of 95 percent paraformaldehyde are slowly added to a reaction vessel containing 27.84 gms of morpholine and 15.45 gms of water keeping the exotherm below 45°C. The resulting solution is filtered yielding a clear solution. EXAMPLE 22 30.0 gms of the PAM microemulsion from Example 2 are placed in a vessel at ambient temperature. To this are slowly added 11.80 gms of the morpholine/CH 2 O adduct of Example 21 with stirring yielding a clear, Mannich PAM microemulsion. After approximately 17 days, the microemulsion is inverted into water giving a Mannich PAM solution with an S.V. of 1.4 mPa·s (1.4 cps) and a CEQ of 3.1 meq/g. EXAMPLE 23 Example 23 shows the preparation of a Mannich PAM microemulsion where formaldehyde and diethylamine are charged sequentially into the PAM microemulsion. 30.0 gms of the PAM microemulsion of Example 3 are placed in a vessel at ambient temperature. To this are slowly added 2.85 gms of 37.2 percent aqueous formaldehyde with stirring. Next, 2.56 gms of diethylamine are slowly added to the microemulsion with stirring, yielding a slightly hazy, Mannich PAM microemulsion. After 24 hours, the microemulsion is inverted into water giving a Mannich PAM solution having an S.V. of 3.58 mPa·s (3.58 cps) and a CEQ of 3.0 meq/g. EXAMPLES 24 and 25 Examples 24 and 25 show the preparation of a diethylamine/dimethylamine/formaldehyde (0.5/0.5/1) adduct and the Mannich PAM microemulsion prepared from this adduct. EXAMPLE 24 10.08 gms of 95 percent paraformaldehyde are slowly added to a reaction vessel containing 12.83 gms of a 56 percent aqueous solution of dimethylamine, 11.67 gms of diethylamine and 8.32 gms of water, keeping the exotherm below 45°C. The resulting solution separates into two layers. The bottom layer, which weighs 32.6 gms is shown by NMR to be the desired diethylamine/dimethylamine/ formaldehyde (0.5/0.5/1) adduct. This layer is collected and used in Example 25 to prepare a Mannich PAM microemulsion. EXAMPLE 25 30.0 gms of the PAM microemulsion of Example 3 are placed in a vessel at ambient temperature. To this is slowly added the diethylamine/dimethylamine/ formaldehyde adduct of Example 24 with stirring to yield a clear, Mannich PAM microemulsion. After approximately 24 hours, the microemulsion is inverted into water giving a Mannich PAM with an S.V. of 2.8 mPa·s (2.8 cps) and a CEQ of 4.04 meq/g. EXAMPLES 26 - 31 Examples 26-28 describe the preparation of PAM copolymer microemulsions using acrylic acid (AA), 2-acrylamido-2-methylpropanesulfonic acid (AMMPS), and diallyl dimethylammonium chloride (DADM), respectively, as the comonomers with acrylamide. Examples 29 - 31 describe the preparation of Mannich PAM microemulsions from these systems. EXAMPLE 26 To 299.3 gms of an organic solution containing 240 gms of IPS, 43.78 gms of PESH and 15.5 gms of SS are slowly added 200 gms of a pH 3.15 aqueous solution containing 80.38 gms of acrylamide, 4.29 gms of acrylic acid and 0.028 gms of N-(2-hydroxyethyl)-ethylenediaminetriacetic acid with stirring. The resulting clear monomer microemulsion is sparged for 40 minutes with nitrogen. 0.0424 gm of 2,2'azobis-4-methoxy-2,4-dimethylvaleronitrile, in 2 mls of ethyl acetate, are then added and the nicroemulsion is polymerized at 30°C. The resulting product is a clear, stable acrylamide-acrylic acid copolymer microemulsion with an S.V. of 3.48 mPa·s (3.48 cps). EXAMPLE 27 To 150 gms of an organic solution containing 120.0 gms of IPS, 15.0 gms of PESH and 15.0 gms of SS are slowly added 100 gms of a pH 8.5 aqueous solution containing 31.22 gms of acrylamide, 11.18 gms of AMMPS and 0.02 gm of N-(2-hydroxyethyl)-ethylenediaminetriacetic acid with stirring. The resulting monomer microemulsion is sparged for 40 minutes with nitrogen. 1.0 gm of a 4.24 percent solution of 2,2'azobis(2,4-dimethylpentane) nitrile in ethyl acetate are then added and the microemulsion is polymerized at 50°C. The resulting product is a clear, stable, acrylamide-AMMPS copolymer microemulsion with an S.V. of 3.0 mPa·s (cps). EXAMPLE 28 To 137.1 gms of an organic solution containing 120 gms of decane, 14.20 gms of PESH and 2.90 gms of polyoxyethylene sorbitan monooleate (POSO) are slowly added 106.97 gms of an aqueous solution containing 17.23 gms of acrylamide, 25.92 gms of DADM and 0.02 gm of N-(2-hydroxyethyl)-ethylenediaminetriacetic acid with stirring. The resulting clear, monomer microemulsion is sparged for 40 minutes with nitrogen. 0.0424 gm of 2,2'-azobis-4methoxy-2,4-dimethylvaleronitrile in 0.8 gm of ethyl acetate is then added and the microemulsion is polymerized at 30°C. The resulting product is a clear, stable acrylamide-DADM copolymer microemulsion with an S.V. of 2.3 mPa·s (cps). EXAMPLE 29 30.0 gms of the acrylamide/acrylic acid copolymer microemulsion of Example 26 are placed in a vessel at ambient temperature. To this are slowly added a solution of 9.50 gms of the DMA/CH 2 O adduct of Example 16 and 0.36 gm of dimethylamine with stirring yielding a Mannich acrylamide-acrylic acid copolymer microemulsion. After approximately 24 hours, the microemulsion is inverted into water giving a Mannich copolymer with an S.V. of 4.1 mPa·s (cps) and a CEQ of 6.33 meq/g. EXAMPLE 30 30.0 gms of the acrylamide/AMMPS copolymer microemulsion of Example 28 are placed in a vessel at ambient temperature. To this are slowly added 7.06 gms of a solution of the DMA/CH 2 O adduct of Example 16 and 0.645 gm of dimethylamine with stirring yielding a Mannich acrylamide-AMMPS copolymer with an S.V. of 1.7 mPa·s (cps) and a CEQ of 4.1 meq/g. EXAMPLE 31 30.0 gms of the acrylamide/DADM copolymer microemulsion of Example 28 are placed in a vessel at ambient temperature. To this are slowly added 4.06 gms of a solution of the DMA/CH 2 O adduct of Example 16 and 0.41 gm of dimethylamine with stirring yielding a Mannich acrylamide-DADM copolymer microemuision. After approximately 24 hours, the microemulsion is inverted into water giving a Mannich copolymer with an S.V. of 2.3 mPa·s (cps) and a CEQ of 6.70 meq/g. EXAMPLES 32 - 63 Examples 32 - 35 describe the preparation of inverse emulsion PAMS with particle sizes of 360 nm (3600Å); 660 nm (6600Å); 1140 nm (11,400Å) and 2050 nm (20,500Å) which are then converted to Mannich PAM inverse emulsions by reacting them with DMA/CH 2 O (1.25/1 and 1/1) adducts in Examples 36 - 39 and 40 - 43, respectively. The products of Examples 17, 19 and 40 - 43 are then used to determine the effect of particle size on flocculation performance. EXAMPLES 32 - 35 The general procedure used to prepare the inverse emulsion PAMS is as follows: DOA and an A/B/A block copolymer of about 5000 m.w. wherein the A units comprise palmitic acid and 12-hydroxystearic acid (1:5) and the B units are polyethyleneoxide (m.w. 1500), hereinafter PHP, are dissolved in low odor paraffin solvent (OPS) to produce an oil solution. An aqueous monomer solution is prepared by dissolving a 52 percent aqueous solution of acrylamide, the disodium salt of ethylenediaminetetraacetic acid (EDTA-2Na) 2,2'-azobis-(2-amidinopropane) hydrochloride and Na 2 SO 4 in water, and then adjusting the pH to 3.0 - 3.5 with 10 percent sulfuric acid. The aqueous monomer solution is then added to the oil solution and emulsified. The resulting inverse emulsion is sparged with nitrogen and then initiated with UV light at 25°C. The polymerization is continued for approximately 3.5 hours. The particle size average is a median value as measured by a Horiba particle size analyzer. The composition of the inverse emulsions and the resulting polymer characteristics are shown below in Table 5. EXAMPLES 36 - 43 The following is a general description of the method used to prepare the Mannich PAM inverse emulsions of Examples 36 - 43. 30.0 gms of PAM inverse emulsion from the previous designated example is placed in a vessel at ambient temperature. To this is slowly added a solution of DMA/CH 2 O adduct with stirring yielding a stable Mannich PAM inverse emulsion. After several days, the Mannich PAM inverse emulsion is inverted into water giving a Mannich PAM and the S.V. and the CEQ are determined. The compositions of the examples and the resulting characteristics are shown in Tables 6 and 8, below. EXAMPLE 44 The performance of the Mannich PAM microemulsion of Example 9 is determined by free-drainage sludge dewatering tests as follows: 200 gms of sewage sludge from the Stamford, CT waste treatment plant is carefully weighed into screw cap jars. Aqueous solutions of Mannich PAM flocculant are prepared so that the concentration of polymer is 0.2%. Various doses of the solutions are added to the sludge samples, water is added to bring the total weight to 250 gms, the sludge is agitated for 90 seconds, the resulting flocculated sludge is poured into a Buchner funnel containing a filter cloth, and the free drainage is determined by measuring the volume of filtrate collected in 10 seconds. The improved performance of Mannich PAM microemulsion from Example 9 (10 days old) compared to a commercially available Mannich PAM is clearly seen in Table 7. Mannich PAM of Example No. Dose (ml) Filtrate (ml) 9 9.5 70 10.5 108 11.0 135 12.5 125 13.0 125 15.0 105 9 11.5 65 12.5 85 13.0 85 15.0 98 16.5 120 17.5 125 20.0 120 EXAMPLE 45 The significance of particle size on performance is determined by free-drainage testing of the aged (72 day old) microemulsions and inverse emulsions as shown in Table 8, below. The test results clearly show the increase in flocculant dose required as the particle size increases. EXAMPLE 46 The procedure of Example 1 is again followed except that the Mannich PAM microemulsion is subjected to treatment with dimethyl sulfate to quaternize the Mannich PAM. A quaternized polymer is recovered. EXAMPLE 47 To 246.05 grams of an organic solution containing IPS (199.7 gms) , PESH (31.6 gms) and SS (13.9 gms) are slowly added 242.5 gms of a pH 3.0 aqueous solution containing acrylamide (109.8 gms) sodium bromate (0.0055 g) and N-(2-hydroxyethyl) - ethylenediaminetriacetic acid (0.10 g) with stirring. The resulting, slightly cloudy, monomer microemulsion is sparged for 40 minutes with nitrogen. SO 2 gas is then bubbled into the resultant microemulsion and the polymerization temperature kept at 55°C. The SO 2 gas is prepared by passing nitrogen gas through a 0.5% sodium metabisulfite solution. The resulting product is a clear, stable, polyacrylamide microemulsion having an S.V. of 2.7 mpa·s (cps). EXAMPLE 48 A. Paraformaldehyde (92.4 gms, 95%) is slowly added to a suitable vessel containing a dimethylamine (218.4 gms, 60.4% aqueous solution) while keeping the exotherm below 45°C. The resulting solution is allowed to cool with stirring and is then filtered yielding a clear solution. B. To 70.0 gms of the product of Example 48A are added 17.13 gms of deionized water. C. To 190.0 gms of the product of Example 48A are added 15.04 gms of dicyanadiamide, 18.62 gms of sodium bisulfite, and 12.86 gms deionized water. The solution is filtered yielding a clear solution. EXAMPLE 49 150 gms of the PAM microemulsion of Example 47 are placed in a reaction vessel at ambient temperature. To this are slowly added 62.7 gms of the DMA/CH 2 O adduct from Example 48B, with stirring, yielding a hazy, Mannich PAM microemulsion. After approximately 24 hours, the microemulsion is inverted into water giving a Mannich PAM with an S.V. of 2.65 mPa·s (cps) and a CEQ of 6.6 meq/g. EXAMPLE 50 150 gms of the PAM microemulsion of Example 47 are placed in a reaction vessel at ambient temperature. To this are slowly added 62.7 gms of the DMA/CH 2 O adduct from Example 48C, with stirring, yielding a clear, Mannich PAM nicroemulsion. After approximatley 24 hours, the microemulsion is inverted into water giving a Mannich PAM with an S.V. of 2.65 mPa·s (cps) and a CEQ of 6.2 meq/g. EXAMPLE 51 75 gms of the Mannich PAM microemulsion of Example 50 are placed in a pressure reactor mounted on a shaker. To this are added 8.5 gms of methylchloride at ambient temperature over a period of approximately 2 hours, keeping the pressure of the reactor under 2.07 bar (30 psi). The resulting product is a clear, stable, quaternized Mannich PAM having an S.V. of 2.1 mPa·s (cps). EXAMPLE 52 50 gms of the Mannich PAM microemulsion of Example 50 are placed in a pressure reactor mounted on a shaker. To this are added 4.5 gms of methylchloride at ambient temperature over a period of approximately 2 hours, keeping the pressure of the reactor under 2.07 bar (30 psi). The resulting product is a clear, stable, quaternized Mannich PAM having an S.V. of 2.2 mPa·s (cps). EXAMPLE 53 50 gms of the Mannich PAM microemulsion of Example 50 are placed in a pressure reactor mounted on a shaker. To this are added 2.9 gms of methylchloride at ambient temperature over a period of approximately 2 hours, keeping the pressure of the reactor under 2.07 bar (30 psi). The resulting product is a clear, stable, quaternized Mannich PAM having an S.V. of 2.4 mPa·s (cps). EXAMPLE 54 50 gms of the Mannich PAM microemulsion of Example 49 are placed in a pressure reactor mounted on a shaker. To this are added 6.0 gms of methylchloride at ambient temperature over a period of approximately 2 hours, keeping the pressure of the reactor under 2.07 bar (30 psi). The resulting product is a clear, stable, quaternized Mannich PAM having an S.V. of 1.8 mPa·s (cps). EXAMPLE 55 150 gms of the PAM microemulsion of Example 47 are placed in a reaction vessel at ambient temperature. To this are slowly added 25.1 gms of the DMA/CH 2 O adduct from Example 48C, with stirring, yielding a hazy, Mannich PAM microemulsion. After approximately 24 hours, the microemulsion is inverted into water giving a Mannich PAM with an S.V. of 2.65 mPa·s (cps). EXAMPLE 56 50 gms of the Mannich PAM microemulsion of Example 55 are placed in a pressure reactor mounted on a shaker. To this are added 2.7 gms of methylchloride at ambient temperature over a period of approximately 2 hours, keeping the pressure of the reactor under 2.07 bar (30 psi). The resulting product is a clear, stable, quaternized Mannich PAM having an S.V. of 1.4 mPa·s (cps). EXAMPLE 57 The performance of the quaternized Mannich PAMs of Examples 51 - 54 and 56 is determined by free drainage sludge dewatering tests as follows: 200 gms of sewage sludge from a municipal waste treatment plant are carefully weighed into jars. Aqueous solutions of the quaternized Mannich PAM flocculant are prepared so that the concentration of polymer is 0.2%. Various doses of the resultant solutions are added to the sludge samples, the sludge agitated for 5 seconds at 300 rpm with an overhead mixer, the resulting flocculated sludge poured into a Buchner funnel containing a filter cloth and the free drainage determined by measuring the milliliters of filtrate collected in 10 seconds. The efficacy of the quaternized polymers (QP) as flocculants is clearly seen in Table 9, below, where they are compared to a commercially available cationic flocculant with similar charge. QP of Example Dosage kg/907.2 kg (lbs/ton) Filtrate Vol. (ml.) 51 1.69 (3.72) 140 2.53 (5.58) 155 3.37 (7.44) 155 4.22 (9.30) 160 52 1.69 (3.72) 140 2.53 (5.58) 155 3.37 (7.44) 155 4.22 (9.30) 160 53 1.69 (3.72) 145 2.53 (5.58) 155 3.37 (7.44) 170 4.22 (9.30) 165 54 1.69 (3.72) 130 2.53 (5.58) 155 3.37 (7.44) 165 4.22 (9.30) 170 56 1.69 (3.72) 48 2.53 (5.58) 50 3.37 (7.44) 60 4.22 (9.30) 95 5.06 (11.16) 110 5.91 (13.02) 115 6.75 (14.88) 120 7.59 (16.74) 128 0.84 (1.86) 125 1.69 (3.72) 140 3.37 (5.88) 148 4.22 (7.44) 148 Example 57 Following the testing procedure set forth above except where modified as indicated, other quaternary polymers falling within the scope of the instant invention are tested as flocculants. The results are set forth in Table 10, below. QP of Example Dosage kg/907.2 kg (lbs/ton) Filtrate Vol. (ml.) Cake Solids Sludge #2 46 (S.V=1.2) 11.34 (25.0) 140 21.2 12.47 (27.5) 148 21.0 13.61 (30.0) 142 21.5 14.74 (32.5) 136 21.1 Comm. 10.21 (22.5) 114 19.7 11.34 (25.0) 142 19.9 12.47 (27.5) 134 20.6 14.74 (30.0) 142 18.6 Sludge #3 46 (S.V=2.0) 18.44 (40.0) 130 10.5 21.77 (48.0) 126 10.5 25.40 (56.0) 128 10.7 46 (S.V.=1.2) 18.44 (40.0) 131 10.2 21.77 (48.0) 134 10.8 25.40 (56.0) 134 11.4 Comm. 10.89 (24.0) 125 9.1 14.51 (32.0) 120 8.3 18.44 (40.0) 108 8.8 Sludge #4 46 (S.V.=1.45) 0.64 (1.4) 14 1.22 (2.7) 33 37.1 1.86 (4.1) 65 41.4 2.45 (5.4) 80 42.0 3.08 (6.8) 90 41.3 Comm. 0.64 (1.4) 22 0.22 (2.7) 58 39.5 1.86 (4.1) 45 32.9 2.45 (5.4) 37 30.2 Sludge #5 46 (S.V.=2.0) 3.73 (8.23) 160 14.8 5.60 (12.35) 205 15.3 7.47 (16.46) 220 15.8 9.34 (20.58) 230 16.3 11.20 (24.69) 230 16.9 46 (S.V.=2.4) 3.73 (8.23) 130 14.2 5.60 (12.35) 210 15.3 7.47 (16.46) 220 16.0 9.34 (20.58) 235 16.5 11.20 (24.69) 236 16.7 Comm 3.37 (8.23) 160 14.1 4.67 (10.29) 200 14.7 5.60 (12.35) 208 15.0 7.47 (16.46) 226 15.1 9.34 (20.58) 214 14.7 Sludge #6 51 (S.V.=2.4) 2.86 (6.3) 134 22.5 3.81 (8.4) 158 24.4 4.76 (10.5) 152 23.4 5.72 (12.6) 160 24.5 Comm. 1.91 (4.2) 146 21.2 2.40 (5.3) 143 21.2 2.86 (6.3) 145 21.5 3.81 (8.4) 138 21.1 Sludge #7 Shear Dosage Fitrate Cake 46 (S.V.=2.5) 300rpm/5min 4.54 (10) 70 13.1 300rpm/10min 4.54 (10) 85 13.3 300rpm/5min 5.31 (11.7) 98 14.0 300rpm/10min 5.31 (11.7) 88 13.3 300rpm/10min 6.03 (13.3) 95 14.0 300rpm/10min 6.80 (15.0) 100 14.6 Comm. 300rpm/8min 3.04 (6.7) 82 12.8 300rpm/15min 3.04 (6.7) 70 13.0 300rpm/5min 3.76 (8.3) 70 12.3 300rpm/10min 3.76 (8.3) 85 13.0 300rpm/15min 3.76 (8.3) 82 13.9 300rpm/15min 4.54 (10.0) 95 13.8 300rpm/15min 5.31 (11.7) 92 12.6 300rpm/30min 5.31 (11.7) 89 14.1 Many variations of the present invention will suggest themselves to those skilled in this art in light of the above detailed description. For example, instead of employing acrylamide as the (alk)acrylamide monomer; methacrylamide and ethacrylamide may be used. Polymerization may be initiated by any known method such as ionizing radiation in addition to ultraviolet or redox initiation. A wide variety of secondary amines are suitable for use in the Mannich reaction such as piperidine, diethanolamine, dibutylamine and amylmethylamine; as are a wide variety of formaldehydes, including trioxane. Although the above discussion is directed primarily to the use of (meth)acrylamide-based polymers which, before functionalization, are substantially linear, it is also possible to use lightly to moderately cross-linked (meth)acrylamide-based polymers which can be prepared by adding small amounts of cross-linking monomers such as methylenebisacrylamide etc. to the aqueous acrylamide monomer solutions prior to polymerization.

Claims: A method of dewatering suspended solids by the addition to said suspended solids of a Mannich (alk)acrylamide-based polymer, comprising preparing said polymer in the form of micelles having particle diameters of 20 to 400 nm (200 to 4000 Å), said micelles being obtainable from a microemulsion. The method as defined in Claim 1, wherein said particle diameters are from 30 to 200 nm (300 to 2000 Å). The method as defined in Claim 2, wherein said particle diameters are from 35 to 100 nm (350 to 1000 Å). The method as defined in any preceding claim, wherein said (alk)acrylamide is acrylamide. The method as defined in any preceding claim, wherein said Mannich acrylamide-based polymer is quaternized. The method as defined in any preceding claim, wherein the polymer is added to said suspended solids as an aqueous solution. The method as defined in Claim 6, wherein the polymer is added to said suspended solids as an aqueous solution prepared by recovering the polymer from said micelles and dispersing the polymer into water. The method as defined in Claim 7, wherein the polymer is recovered from the micelles by precipitating the polymer from the micelles, filtering off the resultant solids and drying the solids to recover the polymer. The method as defined in Claim 8, wherein the polymer is precipitated from the micelles by adding the micelles to a solvent selected from isopropanol and acetone. The method as defined in any preceding claim, wherein the polymer solids content of the microemulsion is greater than 10 percent by weight. The method as defined in any preceding claim, wherein the amount of polymer added to said suspended solids is from 10 to 100,000 parts per million. The method as defined in any preceding claim, wherein said suspended solids comprises a biologically treated suspension. A method as defined in any one of Claims 1-11, wherein said suspended solids comprises paper waste, refinery waste or food waste. A method of dewatering suspended solids by the addition to said suspended solids of a Mannich (alk)acrylamide-based polymer, wherein said polymer is in the form of micelles obtained from a microemulsion, and wherein the micelles have particle diameters of from 20 to 400 nm (200 to 4000 Å). The method of Claim 14, wherein the micelles are formed by: (a) admixing (i) an aqueous solution of at least one (alk)acrylamide monomer and, optionally, at least one ethylenically unsaturated comonomer; (ii) an oil solution comprising at least one hydrocarbon liquid; and (iii) an effective amount of surfactant or surfactant mixture so as to form an inverse microemulsion; (b) subjecting the inverse microemulsion obtained in step (a) to polymerization conditions; and (c) reacting the polymerized polymer obtained in step (b) with an effective amount of a formaldehyde and a secondary amine or a complex thereof; and (d) optionally, quaternizing the resultant polymer. The method of Claim 14, wherein the micelles are formed by: (a) reacting (i) at least one (alk)acrylamide monomer and, optionally, at least one ethylenically unsaturated comonomer; and (ii) a formaldehyde and a secondary amine or a complex thereof in aqueous solution to produce a Mannich (alk)acrylamide monomer; (b) admixing (i) an aqueous solution of at least one said (alk)acrylamide monomer and optional comonomer obtained in (a); (ii) an oil solution comprising at least one hydrocarbon liquid; and (iii) an effective amount of surfactant or surfactant mixture so as to form an inverse microemulsion; (c) subjecting the inverse microemulsion obtained in step (b) to polymerization conditions; and (d) optionally, quaternizing the resultant polymer. The method of Claim 14, wherein the micelles are formed by: (a) admixing (i) an aqueous solution comprising an (alk)acrylamide monomer and, optionally, at least one ethylenically unsaturated comonomer, a formaldehyde and a secondary amine or a complex thereof; (ii) an oil solution comprising at least one hydrocarbon liquid; and (iii) an effective amount of surfactant or surfactant mixture, so as to form an inverse microemulsion; (b) subjecting the inverse microemulsion obtained in step (a) to polymerization conditions and allowing the formaldehyde and secondary amine to react with (alk)acrylamide amide groups; and (c) optionally, quaternizing the resultant polymer. The method of any one of Claims 14 to 17, wherein the micelles have particle diameters of from 30 to 200nm (300 to 2000Å). The method of Claim 18, wherein the micelles have particle diameters from 35 to 100 nm (350 to 1000 Å). The method of any one of Claims 14-19, wherein the polymer is added to said suspended solids as an aqueous solution prepared by inverting the micelles into water, optionally in the presence of a breaker surfactant. The method of any one of Claims 14-19, wherein the polymer is added to said suspended solids as an aqueous solution prepared by recovering the polymer from the micelles and dispersing the polymer into water. The method of any one of Claims 15-17, wherein said (alk)acrylamide monomer comprises acrylamide, said formaldehyde comprises formalin, and said secondary amine comprises dimethylamine. The method of any one of Claims 14-22, wherein the amount of polymer added to said suspended solids is 10 to 100,000 parts per million.

Inventors: DUPLAISE DAVID L, KOZAKIEWICZ JOSEPH J, DUPLAISE, DAVID L., KOZAKIEWICZ, JOSEPH J.
Applicants: CYTEC TECH CORP, CYTEC TECHNOLOGY CORP.
Application year: 1989
Main classification: C08F8
IPC codes: D21H21, C08J3, C08F8, D21H17