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Patent US6605674 - Structurally-modified polymer flocculants - Google Patenten
This invention is directed to structurally-modified water-soluble polymers prepared by initiating polymerization of an aqueous solution of monomers under free radical polymerization conditions to form a polymer solution and adding at least one structural modifier to the polymer solution after at least...http://www.google.nl/patents/US6605674?utm_source=gb-gplus-sharePatent US6605674 - Structurally-modified polymer flocculants
Publicatienummer US6605674 B1
Aanvraagnummer US 09/606,581
Publicatiedatum 12 aug 2003
Aanvraagdatum 29 juni 2000
Prioriteitsdatum 29 juni 2000
Ook gepubliceerd als CA2406270A1, CA2406270C, CN1239544C, CN1426429A, EP1297039A1, EP1297039A4, EP1297039B1, US6753388, WO2002002662A1
Publicatienummer 09606581, 606581, US 6605674 B1, US 6605674B1, US-B1-6605674, US6605674 B1, US6605674B1
Uitvinders Wesley L. Whipple, Chidambaram Maltesh, Cathy C. Johnson, Ananthasubramanian Sivakumar, Tracey M. Guddendorf, Angela P. Zagala
Oorspronkelijke patenteigenaar Ondeo Nalco Company
Patentcitaties (13), Verwijzingen naar dit patent (58), Classificaties (26), Juridische gebeurtenissen (12)
Structurally-modified polymer flocculants
US 6605674 B1
This invention is directed to structurally-modified water-soluble polymers prepared by initiating polymerization of an aqueous solution of monomers under free radical polymerization conditions to form a polymer solution and adding at least one structural modifier to the polymer solution after at least 30% polymerization of the monomers has occurred, and to use of the water-soluble cross-linked polymers as flocculating agents.
1. A structurally-modified nonionic, cationic or anionic water-soluble polymer, the polymer comprising a mixture of linear polymer and long-chain branched polymer, said polymer mixture having a reduced specific viscosity above 3 dl/g, wherein the polymer is prepared by initiating polymerization of an aqueous solution of monomers under free radical polymerization conditions to form a polymer solution and adding at least one structural modifier to the polymer solution after at least 30% polymerization of the monomers has occurred.
2. The structurally-modified water-soluble polymer according to claim 1 selected from the group consisting of emulsion polymers, dispersion polymers and gel polymers.
3. The structurally-modified nonionic, cationic or anionic structurally-modified water-soluble polymer according to claim 1 wherein the monomers are selected from the group consisting of acrylamide, methacrylamide, diallyldimethylammonium chloride, dimethylaminoethyl acrylate methyl chloride quaternary salt, acrylamidopropyltrimethylammonium chloride, dimethylaminoethyl methacrylate methyl chloride quaternary salt, methacrylamidopropyltrimethylammonium chloride, acrylic acid, sodium acrylate, ammonium acrylate, methacrylic acid, sodium methacrylate, and ammonium methacrylate.
4. The structurally-modified water-soluble polymer of claim 1 wherein the structural modifier is selected from the group consisting of cross-linking agents, chain transfer agents and mixtures thereof.
5. The structurally-modified water-soluble polymer of claim 4 wherein the chain transfer agents are selected from the group consisting of alcohols, sulfur compounds, carboxylic acids or salts thereof, phosphites, and combinations thereof.
6. The structurally-modified water-soluble polymer of claim 5 wherein the chain transfer agents are selected from sodium formate and sodium hypophosphite.
7. The structurally-modified water-soluble polymer of claim 1 wherein the monomers are acrylamide and dimethylaminoethylacrylate methyl chloride quaternary salt and the structural modifier is sodium hypophosphite.
8. A method of preparing a structurally-modified nonionic, cationic or anionic water-soluble polymer, the polymer comprising a mixture of linear polymer and long-chain branched polymer, said polymer mixture having a reduced specific viscosity above 3 dl/g, comprising initiating polymerization of an aqueous solution of monomers under free radical polymerization conditions to form a polymer solution and adding at least one structural modifier to the polymer solution after at least 30% polymerization of the monomers has occurred.
This invention is directed to structurally-modified water-soluble polymers prepared by initiating polymerization of an aqueous solution of monomers under free radical polymerization and adding at least one modifier after at least 30% polymerization of the monomers has occurred, and to the use of the polymers as flocculants.
Water-soluble polymeric flocculants are commonly used for clarifying suspensions of organic matter of a proteinaceous or cellulosic nature such as those found in sewage and industrial plant treatment effluents or in paper mills.
While strictly mechanical means have been used to effect solids/liquid separation, modem methods often rely on mechanical separation techniques that are augmented by synthetic and natural polymeric materials to accelerate the rate at which solids can be removed from water. These processes include the treatment of raw water with cationic coagulant polymers that settle suspended inorganic particulates and make the water usable for industrial or municipal purposes. Other examples of these processes include the removal of colored soluble species from paper mill effluent wastes and the use of polymeric flocculants for the treatment of industrial water, as sludge conditioners for the treatment of municipal water systems, as retention and drainage aids in the manufacture of paper, as chemicals for recovering useful and valuable substances from white water in the papermaking process and in emulsion breaking.
Regarding the mechanism of separation processes, particles in nature have either a cationic or anionic charge. Accordingly, these particles often are removed by a water-soluble coagulant or flocculant polymer having a charge opposite to that of the particles. This is referred to as a polyelectrolyte enhanced solids/liquid separation process, wherein a water-soluble or dispersible ionically charged polymer is added to neutralize the charged particles or emulsion droplets to be separated. The dosage of these polymers is critical to the performance of the process. Too little ionically charged polymer, and the suspended particles will not be charge neutralized and will thus still repel each other. Too much polymer, and the polymer will be wasted, or worse, present a problem in and of itself.
Notwithstanding the variety of commercially available polymers that have been found to be capable of flocculating or coagulating sludges, there are various circumstances which tend to limit the usefulness of these reagents. While for certain sludges economical treatments with these known reagents are feasible, more often sludges require very high and cost-ineffective dosages of reagents for successful treatment. Moreover, variations often occur in sludge from any one source. For example, variations in the supply of material to the waste water/sludge/paper furnish process water and/or in the oxidizing conditions that may be involved in the production of these waters lead to a variety of particle types which must be removed. Furthermore, it is not uncommon to encounter sludges that are, for some reason, not amenable to flocculation by any of the known polymeric flocculating agents.
Therefore, there is a need for an improved family of polymers that provide better drainage at lower doses in sludge dewatering. Likewise, there is a continuing need for treatments to increase the efficiency of pulp and paper manufacture.
EP 202,780 discloses particulate cross-linked copolymers of acrylamide with at least 5 mole percent dialkylaminoalkyl acrylate for use as flocculants in high-shear applications.
The addition of a cross-linking agent both at the beginning, and during the polymerization process under conditions such that its availability for reaction is substantially constant throughout the process is disclosed in U.S. Pat. No. 4,950,725.
EP 374,458 discloses water-soluble branched high molecular weight cationic flocculants formed from monomers polymerized in the presence of chain transfer agents such as isopropanol and branching agents such as methylene bisacrylamide, in which the chain transfer agent is added to prevent cross linking. Cross linking can render the polymer insoluble in water.
Addition of chain transfer agent at the conclusion of polymerization of a DADMAC/acrylamide copolymer to produce a linear higher molecular weight copolymer is disclosed in EP 363,024.
U.S. Pat. No. 4,913,775 discloses use of substantially linear cationic polymers such as acrylamide/dimethylaminoethyl acrylate methyl chloride quaternary salt copolymers and bentonite as additives in pulp or paper manufacture.
U.S. Pat. No. 5,393,381 discloses use of a branched cationic polyacrylamide powder such as an acrylamide/dimethylaminoethyl acrylate quaternary salt copolymer and bentonite for paper or cardboard manufacture.
We have discovered that the late stage addition to a polymerization reaction of a structural modifier as described herein results in formation of a more effective, structurally-modified flocculant. When the structural modifier is a chain-transfer agent, the resulting water-soluble polymers typically have a faster rate of solubilization, higher reduced specific viscosities and are more active than unmodified analogs. This is applicable to cationic, anionic, or nonionic polymers, synthesized using water-in-oil emulsion, dispersion, or gel polymerization techniques.
Accordingly, in its principal aspect, this invention is directed to a water-soluble polymer prepared by initiating polymerization of an aqueous solution of monomers under free radical polymerization conditions to form a polymer solution and adding at least one structural modifier to the polymer solution after at least 30% polymerization of the monomers has occurred.
“DMAEA. BCQ” for dime thylaminoethyl acrylate, benzyl chloride quaternary salt.
“DMAEA. MCQ” for dimethylaminoethyl acrylate, methyl chloride quaternary salt.
“EDTA. 4Na+” for ethylenediaminetetraacetic acid, tetrasodium salt.
“Alfonic® 1412-60” is a ethoxylated linear alcohol (60% ethylene oxide), available from Vista Chemical Co., Houston, Tex.
“Triton® N-101 ” for nonylphenoxy polyethoxy ethanol, available from Rohm and Haas Co., Philadelphia, Pa.
“Tween 61 ” for POE (4) sorbitan monostearate, available from ICI Specialty Chemicals, Wilmington, Del.
“AIBN” for 2,2′-azobis(isobutyronitrile), available from E. I. duPont Nemours & Co. Inc.; Wilmington, Del.
“AIVN” for 2,2′-azobis(2,4-dimethylvaleronitrile), available from E. I. duPont Nemours & Co. Inc.; Wilmington, Del.
“RSV” stands for Reduced Specific Viscosity. Within a series of polymer homologs which are substantially linear and well solvated, “reduced specific viscosity (RSV)” measurements for dilute polymer solutions are an indication of polymer chain length and average molecular weight according to Paul J. Flory, in “Principles of Polymer Chemistry”, Cornell University Press, Ithaca, N.Y., ® 1953, Chapter VII, “Determination of Molecular Weights”, pp. 266-316. The RSV is measured at a given polymer concentration and temperature and calculated as follows: RSV = [ ( η / η o ) - 1 ] c η = viscosity of polymer solution η o = viscosity of solvent at the same temperature c = concentration of polymer in solution.
The units of concentration “c” are (grams/100 ml or g/deciliter). Therefore, the units of RSV are dl/g. In this patent application, a 1.0 molar sodium nitrate solution is used for measuring RSV, unless specified. The polymer concentration in this solvent is 0.045 g/dl. The RSV is measured at 30° C. The viscosities η and ηo are measured using a Cannon Ubbelohde semimicro dilution viscometer, size 75. The viscometer is mounted in a perfectly vertical position in a constant temperature bath adjusted to 30±0.02° C. The error inherent in the calculation of RSV is about 2 dl/grams. When two polymer homologs within a series have similar RSV's that is an indication that they have similar molecular weights.
“Raw water” means water from natural geographical sources including rivers, lakes, well water, rain water, and the like.
“Process water” means water used in a process such as a manufacturing process (paper machine), steel production, chemical production processes, refinery processes, food production processes (i.e., sugar process), and the like.
“Waste water” means water from a manufacturing process, municipal waste or other waters which are required to be treated prior to discharge to a receiving stream, lake or other water way.
“Papermaking process” means a method of making paper products from pulp comprising forming an aqueous cellulosic papermaking furnish, draining the furnish to form a sheet and drying the sheet. The steps of forming the papermaking furnish, draining and drying may be carried out in any conventional manner generally known to those skilled in the art. Conventional coagulants, conventional flocculants, microparticles, alum, cationic starch or a combination thereof may be utilized as adjuncts with the structurally-modified water-soluble polymer of this invention, though it must be emphasized that no adjunct is required for effective retention and drainage activity.
Representative non-ionic, water-soluble monomers include acrylamide, methacrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, N-isopropylacrylamide, N-vinylformamide, N-vinylmethylacetamide, N-vinyl pyrrolidone, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, N-t-butylacrylamide, N-methylolacrylamide, and the like.
Representative anionic monomers include acrylic acid, and it's salts, including, but not limited to sodium acrylate, and ammonium acrylate, methacrylic acid, and it's salts, including, but not limited to sodium methacrylate, and ammonium methacrylate, 2-acrylamido-2-methylpropanesulfonic acid (AMPS), the sodium salt of AMPS, sodium vinyl sulfonate, styrene sulfonate, maleic acid, and it's salts, including, but not limited to the sodium salt, and ammonium salt, sulfonate itaconate, sulfopropyl acrylate or methacrylate or other water-soluble forms of these or other polymerisable carboxylic or sulphonic acids. Sulfomethylated acrylamide, allyl sulfonate, sodium vinyl sulfonate, itaconic acid, acrylamidomethylbutanoic acid, fumaric acid, vinylphosphonic acid, vinylsulfonic acid, allylphosphonic acid, sulfomethyalted acryamide, phosphonomethylated acrylamide, and the like.
Representative cationic monomers include dialkylaminoalkyl acrylates and methacrylates and their quaternary or acid salts, including, but not limited to, dimethylaminoethyl acrylate methyl chloride quaternary salt, dimethylaminoethyl acrylate methyl sulfate quaternary salt, dimethyaminoethyl acrylate benzyl chloride quaternary salt, dimethylaminoethyl acrylate sulfuric acid salt, dimethylaminoethyl acrylate hydrochloric acid salt, dimethylaminoethyl methacrylate methyl chloride quaternary salt, dimethylaminoethyl methacrylate methyl sulfate quaternary salt, dimethylaminoethyl methacrylate benzyl chloride quaternary salt, dimethylaminoethyl methacrylate sulfuric acid salt, dimethylaminoethyl methacrylate hydrochloric acid salt, dialkylaminoalkylacrylamides or methacrylamides and their quaternary or acid salts such as acrylamidopropyltrimethylammonium chloride, dimethylaminopropyl acrylamide methyl sulfate quaternary salt, dimethylaminopropyl acrylamide sulfuric acid salt, dimethylaminopropyl acrylamide hydrochloric acid salt, methacrylamidopropyltrimethylammonium chloride, dimethylaminopropyl methacrylamide methyl sulfate quaternary salt, dimethylaminopropyl methacrylamide sulfuric acid salt, dimethylaminopropyl methacrylamide hydrochloric acid salt, diethylaminoethylacrylate, diethylaminoethylmethacrylate, diallyldiethylammonium chloride and diallyldimethyl ammonium chloride. Alkyl groups are generally C1-4 alkyl.
“Chain transfer agent” means any molecule, used in free-radical polymerization, which will react with a polymer radical forming a dead polymer and a new radical. In particular, adding a chain transfer agent to a polymerizing mixture results in a chain-breaking and a concommitant decrease in the size of the polymerizing chain. Thus, adding a chain transfer agent limits the molecular weight of the polymer being prepared. Representative chain transfer agents include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, butyl alcohol, and glycerol, and the like, sulfur compounds such as alkylthiols, thioureas, sulfites, and disulfides, carboxylic acids such as formic and malic acid, and their salts and phosphites such as sodium hypophosphite, and combinations thereof. See Berger et al., “Transfer Constants to Monomer, Polymer, Catalyst, Solvent, and Additive in Free Radical Polymerization,” Section II, pp. 81-151, in “Polymer Handbook,” edited by J. Brandrup and E. H. Immergut, 3 d edition, John Wiley & Sons, New York (1989) and George Odian, Principles of Polymerization, second edition, John Wiley & Sons, New York (1981). A preferred alcohol is 2-propanol. Preferred sulfur compounds include ethanethiol, thiourea, and sodium bisulfite. Preferred carboxylic acids include formic acid and its salts. More preferred chain-transfer agents are sodium hypophosphite and sodium formate.
The water-soluble modified polymers prepared as describe herein may be cationic, anionic or non-ionic. They may be emulsion polymers, dispersion polymers, or gel polymers.
“Emulsion polymer” and “latex polymer” mean a water-in-oil polymer emulsion comprising a cationic, anionic or nonionic polymer according to this invention in the aqueous phase, a hydrocarbon oil for the oil phase and a water-in-oil emulsifying agent. Inverse emulsion polymers are hydrocarbon continuous with the water-soluble polymers dispersed within the hydrocarbon matrix. The inverse emulsion polymers are then “inverted” or activated for use by releasing the polymer from the particles using shear, dilution, and, generally, another surfactant. See U.S. Pat. No. 3,734,873, incorporated herein by reference. Representative preparations of high molecular weight inverse emulsion polymers are described U.S. Pat. Nos. 2,982,749;3,284,393; and 3,734,873. See also, “Mechanism, Kinetics and Modeling of the Inverse-Microsuspension Homopolymerization of Acrylamide,” Hunkeler, et al., Polymer (1989), 30(1), 127-42; and “Mechanism, Kinetics and Modeling of Inverse-Microsuspension Polymerization: 2. Copolymerization of Acrylamide with Quaternary Ammonium Cationic Monomers,” Hunkeler et al., Polymer (1991), 32(14), 2626-40.
The oil phase is prepared by mixing together an inert hydrocarbon liquid with one or more oil soluble surfactants. The surfactant mixture should have a low HLB, to ensure the formation of an oil continuous emulsion. Appropriate surfactants for water-in-oil emulsion polymerizations, which are commercially available, are compiled in the North American Edition of McCutcheon's Emulsifiers & Detergents. The oil phase may need to be heated to ensure the formation of a homogeneous oil solution.
The resulting emulsion polymer is a free-flowing liquid. An aqueous solution of the waterin-oil emulsion polymer can be generated by adding a desired amount of the emulsion polymer to water with vigorous mixing in the presence of a high-HLB surfactant (as described in U.S. Pat. No. 3,734,873).
In a typical procedure for preparing a dispersion polymer, an aqueous solution containing one or more inorganic or hydrophobic salts, one or more water-soluble monomers, any polymerization additives such as processing aids, chelants, pH buffers and a water-soluble stabilizer polymer is charged to a reactor equipped with a mixer, a thermocouple, a nitrogen purging tube, and a water condenser. The monomer solution is mixed vigorously, heated to the desired temperature, and then a water-soluble initiator is added. The solution is purged with nitrogen while maintaining temperature and mixing for several hours. After this time, the mixture is cooled to room temperature, and any post-polymerization additives are charged to the reactor. Water continuous dispersions of watersoluble polymers are free flowing liquids with product viscosities generally 100-10,000 cP, measured at low shear.
The polymerization reactions described herein are initiated by any means which results in generation of a suitable free-radical. Thermally derived radicals, in which the radical species results from thermal, homolytic dissociation of an azo, peroxide, hydroperoxide and perester compound are preferred. Especially preferred initiators are azo compounds including 2,2′-azobis(2 amidinopropane) dihydrochloride, 2,2′-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride, 2,2′-azobis(isobutyronitrile) (AIBN), 2,2′-azobis(2,4-dimethylvaleronitrile) (AIVN), and the like.
Where the structural modifier is a cross-linking agent, polymers formed by the addition of a cross-linking agent to the polymerization generally between 30% and 99% conversion, preferably between 50 and 90% conversion, and frequently between 65 and 85% conversion, are more active than the unmodified polymers which are substantially linear, cross-linked, water-insoluble particles disclosed in U.S. Pat. No. 4,950,725 and EP 202,780 and the highly branched, water-soluble polymers disclosed in U.S. Pat. No. 5,945,494.
The polymers modified with a cross-linking agent after the start of polymerization differ from the particulate polymer flocculants disclosed in U.S. Pat. No. 4,950,725 and EP 202,780 that are swellable, but, insoluble in water. These particles are formed either through the addition of a watersoluble cross-linking agent, or a mixture of different cross-linking reagents with different reactivities, usually polyethylenically unsaturated monomers at the front-end, or alternatively both at the beginning of the process and at or near the end of the process such that the availability of the cross-linker is substantially constant throughout the reaction or by cross-linking preformed watersoluble polymers. Polymers modified with a cross-linking agent as described herein are not particulate in aqueous solution.
The polymers of this invention also differ from polymers disclosed in U.S. Pat. No. 5,945,494, which are water-soluble, highly branched species. Essential to the formation of these polymers is the inclusion of a molecular weight modifying, or chain-transfer agent in combination with high levels of a branching agent (4 to 80 ppm, based on initial molar content) to form highly-branched, watersoluble polymers. As stated in U.S. Pat. No. 5,945,494 column 5, lines 35-38, in the absence of a chaintransfer agent, the incorporation of even extremely small amounts of branching agent, e.g. 5 parts per million may cause crosslinking, rendering the polymer insoluble in water. The combination of a branching agent and a molecular weight modifying agent included in the aqueous monomer solution at the start of reaction as disclosed in U.S. Pat. No. 5,945,494, will yield highly branched polymers with polymer chains of limited molecular weight.
It is believed that polymers modified with a cross-linking agent after the start of polymerization described herein contain a mixture of linear high molecular weight polymer formed during the initial part of the reaction, and long-chain branched polymer formed during the latter part of the reaction. For aqueous solutions made-up from polymers modified using late addition of a cross-linking agent, it is possible that water-soluble, non-particulate, aggregates of several entangled polymer chains exist. Macromolecular entanglements have been proposed for high molecular weight polymers, formed by free-radical polymerization methods (Gardner, et. al., J. Applied Polymer Science, 22 881-882, (1978); A. Wan, Polymer Preprints, Am. Chem. Soc., Division of Polymer Chemistry, 37(2), 655, (1996).
In a preferred aspect of this invention, the structurally-modified water-soluble polymer is selected from the group consisting of emulsion polymers, dispersion polymers and gel polymers.
In another preferred aspect, the monomers are selected from acrylamide or methacrylamide and one or more monomers selected from the group consisting of diallyldimethylammonium chloride, dimethylaminoethyl acrylate methyl chloride quaternary salt, acrylamidopropyltrimethylammonium chloride, dimethylaminoethyl methacrylate methyl chloride quaternary salt, methacrylamidopropyltrimethylammonium chloride, acrylic acid, sodium acrylate, ammonium acrylate, methacrylic acid, sodium methacrylate, and ammonium methacrylate.
In another preferred aspect, the structural modifier is selected from the group consisting of cross-linking agents, chain transfer agents and mixtures thereof.
In another preferred aspect, the chain transfer agents are selected from the group consisting of alcohols, sulfur compounds, carboxylic acids or salts thereof, phosphites, and combinations thereof.
In another preferred aspect, the chain transfer agents are selected from sodium formate and sodium hypophosphite.
In another preferred aspect, the cross-linking agent is selected from the group consisting of N,N-methylenebisacrylamide, N,N-methylenebismethacrylamide, triallylamine, triallyl ammonium salts, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, N-vinyl acrylamide, N-methyl allylacrylamide, vinyltrimethoxysilane, and combinations thereof.
In another preferred aspect, the cross-linking agent is vinyltrimethoxysilane.
In another preferred aspect, the cross-linking agent is methylenebisacrylamide.
In another preferred aspect, the monomers are acrylamide and dimethylaminoethylacrylate benzyl chloride quaternary salt and the structural modifier is vinyltrimethoxysilane.
In another preferred aspect, the monomers are acrylamide and diallyldimethylammonium chloride and the structural modifier is vinyltrimethoxysilane.
In another preferred aspect, the monomers are acrylamide and dimethylaminoethylacrylate methyl chloride quaternary salt and the structural modifier is methylenebisacrylamide.
In another preferred aspect, the monomers are acrylamide and dimethylaminoethylacrylate methyl chloride quaternary salt and the structural modifier is sodium formate.
In another preferred aspect, the monomers are acrylamide and dimethylaminoethylacrylate methyl chloride quaternary salt and the structural modifier is sodium hypophosphite.
In another preferred aspect, the monomers are acrylamide and dimethylaminoethylacrylate methyl chloride quaternary salt and the structural modifier is a combination of sodium formate and methylenebisacrylamide.
In another preferred aspect, the monomers are acrylamide, dimethylaminoethylacrylate benzyl chloride quaternary salt and dimethylaminoethylacrylate methyl chloride quaternary salt and the structural modifier is methylenebisacrylamide.
In another preferred aspect, the monomers are acrylamide, dimethylaminoethylacrylate benzyl chloride quaternary salt and dimethylaminoethylacrylate methyl chloride quaternary salt and the structural modifier is sodium formate.
In another preferred aspect, the monomers are acrylamide, dimethylaminoethylacrylate benzyl chloride quaternary salt and dimethylaminoethylacrylate methyl chloride quaternary salt and the structural modifier isa combination of methylenebisacrylamide and sodium formate.
In another preferred aspect, the monomers are acrylamide, dimethylaminoethylacrylate benzyl chloride quaternary salt and dimethylaminoethylacrylate methyl chloride quaternary salt and the structural modifier is vinyltrimethoxysilane.
In another preferred aspect, the monomers are acrylamide and acrylic acid or a salt thereof and the structural modifier is sodium hypophosphite.
In another aspect, this invention is directed to a method of preparing a structurally-modified water-soluble polymer comprising initiating polymerization of an aqueous solution of monomers under free radical polymerization conditions to form a polymer solution and adding at least one structural modifier to the polymer solution after at least 30% polymerization of the monomers has occurred.
In another aspect, this invention is directed to a method of flocculating an aqueous suspension of organic matter comprising adding to the suspension an effective flocculating amount of the structurally-modified water-soluble polymer prepared by initiating polymerization of an aqueous solution of monomers under free radical polymerization conditions to form a polymer solution and adding at least one structural modifier to the polymer solution after at least 30% polymerization of the monomers has occurred.
In another aspect, this invention is directed to a method of clarifying waste water comprising adding to the waste water an effective flocculating amount of a structurally-modified water-soluble polymer prepared by initiating polymerization of an aqueous solution of monomers under free radical polymerization conditions to form a polymer solution and adding at least one structural modifier to the polymer solution after at least 30% polymerization of the monomers has occurred.
The effective flocculating amount of the structurally-modified water-soluble polymer depends on the characteristics of the water being treated and can be readily determined by one of ordinary skill in the art. Polymer should be dosed at a sufficient level to cause flocculation of the dispersed material and cause improved settling. Typical dosages are from about 10 to 1,000 ppm, preferably from about 15 to about 400 ppm and more preferably from about 20 to about 200 ppm based on polymer actives.
In another aspect, this invention is directed to a method of increasing retention and drainage in a papermaking furnish comprising adding to the furnish an effective amount of a structurally-modified water-soluble polymer prepared by initiating polymerization of an aqueous solution of monomers under free radical polymerization conditions to form a polymer solution and adding at least one structural modifier to the polymer solution after at least 30% polymerization of the monomers has occurred.
The effective amount of the structurally-modified water-soluble polymer depends on the characteristics of the particular papermaking furnish and can be readily determined by one of ordinary skill in the papermaking art. Typical dosages are from about 0.01 to about 6, preferably from about 0.1 to about 4 and more preferably from about 0.1 to about 2 pounds polymer actives/ton solids in the furnish.
The structurally-modified water-soluble polymer of this invention may also be used in combination with a coagulant as part of a dual polymer treatment program. The retention and drainage properties of the furnish may also be improved by addition of a microparticle is described in U.S. Pat. Nos. 4,753,710 and 4,913,775 incorporated herein by reference.
“Microparticles” means highly charged materials that improve flocculation when used together with natural and synthetic macromolecules. Microparticles are used in combination with other wet end additives to improve retention and drainage on the paper machine. Microparticles encompass a broad set of chemistries including polysilicate microgel, structured colloidal silicas, colloidal alumina, polymers including copolymers of acrylic acid and acrylamide and and naphthalene sulfonate/formaldehyde condensate polymers, bentonite and mineral clays such as montmorillonite, saponite and smectite types and colloidal silica in its many forms including modified colloidal silicic acids such as those described in PCT/US98/19339.
Representative copolymers of acrylic acid and acrylamide usefil as microparticles include Nalco® 8677 PLUS, available from Nalco Chemical Company, Naperville, Ill., USA. Other copolymers of acrylic acid and acrylamide are described in U.S. Pat. No. 5,098,520, incorporated herein by reference.
“Bentonites” include any of the materials commercially referred to as bentonites or as bentonite-type clays, i.e., anionic swelling clays such as sepialite, attapulgite and montmorillonite. In addition, the bentonites described in U.S. Pat. No. 4,305,781 are suitable. A preferred bentonite is a hydrated suspension of powdered bentonite in water. Powdered bentonite is available as Nalbrite™, from Nalco Chemical Company.
Representative dispersed silicas have an average particle size of from about 1 to about 100 nanometers (nm), preferably from about 2 to about 25 nm, and more preferably from about 2 to about 15 nm. This dispersed silica, may be in the form of colloidal, silicic acid, silica sols, fumed silica, agglomerated silicic acid, silica gels, precipitated silicas, and all materials described in Patent Cooperation Treaty Patent Application No. PCT/US98/19339, so long as the particle size or ultimate particle size is within the above ranges. Dispersed colloidal silica in water with a typical particle size of 4 nm is available as Nalco® 8671, from Nalco Chemical Company. Another type of inorganic colloid used as a microparticle is a borosilicate in water; available as Nalco® 8692, from Nalco Chemical Company. Other types of colloidal silica and modified colloidal silicas are commercially available from E.I. DuPont de Nemours and Co., Wilmington, Del. under the tradename Ludox® from Akzo Nobel, Surte, Sweden (BMA or NP Series), from Vinings Industries Inc., Atlanta, Ga. and from Nissan Chemical Industries, Ltd., Tokyo, Japan.
Representative naphthalene sulfonate/formaldehyde condensate polymers include Nalco® 8678 from Nalco Chemical Company.
The microparticle is added to the papermaking funish either before or after the structurally-modified polymer is added to the furnish. The choice of whether to add the microparticle before or after the polymer can be made by a person of ordinary skill in the art based on the requirements and specifications of the papermaking furnish.
In another aspect, this invention is directed to a method of increasing retention and drainage in a papermaking furnish comprising adding to the furnish a microparticle and an effective amount of a structurally-modified water-soluble polymer prepared by initiating polymerization of an aqueous solution of monomers under free radical polymerization conditions to form a polymer solution and adding at least one structural modifier to the polymer solution after at least 30% polymerization of the monomers has occurred.
In another aspect, this invention is directed to a method of increasing retention and drainage in a papermaking furnish comprising adding to the furnish a microparticle, a coagulant and an effective amount of a structurally-modified water-soluble polymer prepared by initiating polymerization of an aqueous solution of monomers under free radical polymerization conditions to form a polymer solution and adding at least one structural modifier to the polymer solution after at least 30% polymerization of the monomers has occurred.
In another aspect, this invention is directed to a method of flocculating an aqueous coal refuse slurry comprising adding an effective amount of a structurally-modified water-soluble polymer prepared by initiating polymerization of an aqueous solution of monomers under free radical polymerization conditions to form a polymer solution and adding at least one structural modifier to the polymer solution after at least 30% polymerization of the monomers has occurred.
The foregoing may be better understood by reference to the following examples which are presented for purposes of illustration and are not intended to limit the scope of the invention. Examples 1-10 illustrate the embodiment of the invention which is late addition of cross linker; Examples 11-14, 25 and 26 illustrate the embodiment of the invention which is late addition of chain transfer agent; and Examples 15-23 illustrate the embodiment of the invention which is late addition of both cross-linker and chain transfer agent.
POLYMERS MODIFIED BY LATE ADDITION OF CROSS LINKING AGENTS EXAMPLE 1
Polymer 1, a control polymer of 15% polymer solids, 90/10 mole percent AcAm/DMAEA.BCQ dispersion is synthesized in the following manner:
To a 1500 ml reaction flask fitted with a mechanical stirrer, thermocouple, condenser, nitrogen purge tube and addition port is added 213 g of a 49.6% aqueous solution of acrylamide (Nalco Chemical Company, Naperville, Ill.), 56.6 g of dimethylaminoethylacrylate benzyl chloride quaternary salt (70.9% aqueous solution, Nalco Chemical Company, Naperville, Ill.), 9 g of glycerin, 59 g of the copolymer of dimethylaminoethylacrylate benzyl chloride quaternary salt and diallyldimethylammonium chloride (15% aqueous solution, Nalco Chemical Company, Naperville, Ill.), 0.4 g of ethylenediaminetetraacetic acid, tetrasodium salt, 157 g of ammonium sulfate and 424 g of deionized water. The mixture is then heated to 48° C. while stirring at 900 rpm. After reaching 48° C., 1.2 g of a 1.0% aqueous solution of 2,2′-azobis(2-amidinopropane) dihydrochloride (V-50, Wako Chemicals, Dallas, Tex.) is added to the reaction mixture, the system is purged with nitrogen and the temperature is maintained at 48° C. Two hours after initiation, 3.8 g of a 1.0% aqueous solution of 2,2′-azobis(2-amidinopropane) dihydrochloride is added to the reaction and at three hours after initiation 6.0 g of dimethylaminoethylacrylate benzyl chloride quaternary salt and at four hours 4 g of a 10% aqueous solution of 2,2′-azobis(2-amidinopropane) dihydrochloride is added. At six hours the reaction is cooled to ambient temperature and 55.0 g of sodium sulfate, 10.0 g sodium thiosulfate, and 10.0 g acetic acid are added. The resulting product is a smooth milky white dispersion with a bulk viscosity of 30 cP (centipoise) and a reduced specific viscosity of 17.8 dl/g (0.045% polymer in 0.125 N NaNO3 solution at 30° C.).
Polymer 2, a vinyltrimethoxysilane modified 15% polymer solids, 90/10 mole percent AcAm/DMAEA.BCQ dispersion polymer is synthesized using the general procedure described in Example 1. The standard method is modified by adding 0.25 g vinyltrimethoxysilane (Huls America, Inc., Bristol, Pa.) to the reaction mixture at 3.5 hours after initiation (approximately 88% conversion). No further modifications are made. The reduced specific viscosity of the product is 18.3 dl/g (0.045% polymer in 0.125 N NaNO3 solution at 30° C.).
Polymer 3, a vinyltrimethoxysilane modified 15% polymer solids, 90/10 mole percent AcAm/DMAEA.BCQ dispersion is synthesized using the general procedure described in Example 1. The standard method is modified by addition of 0.10 g vinyltrimethoxysilane (Huls America, Inc. Bristol, Pa.) to the reaction mixture at 3 hours after initiation (approximately 86% conversion). No further modifications are made. The resulting product is a smooth milky white dispersion has a bulk viscosity of 30 cP and a reduced specific viscosity of 16 dl/g (0.045% polymer in 0.125 N NaNO3 solution at 30° C.).
Polymer 4, a VTMS modified 15% solids, 90/10 mole percent AcAm/DMAEA.MCQ is synthesized using the following procedure.
To a 1500 ml resin flask equipped with a stirrer, temperature controller, nitrogen sparge tube and water condenser is added 335.2 g of deionized water, 230.3 g of a 48.6% aqueous solution of acrylamide (Nalco Chemical Co., Naperville, Ill.), 43.6 g of dimethlyaminoethylacrylate methyl chloride quaternary salt (DMAEA.MCQ, 80%, NCF Manufacturing, Riceboro, Ga.), 50.0 g of a 15% solution of poly(dimethlaminoethylmethacrylate methyl chloride quaternary salt, Nalco Chemical Co., Naperville, Ill.), 5.0 g of adipic acid, 13.5 g of glycerol, 0.42 g of EDTA.4 Na+and 302.0 g ammonium sulfate. The mixture is heated to 48° C. and 1.0 g of a 1% solution of V-50 is added. The resulting solution is sparged with nitrogen at the rate of 1000 ml/min. After 15 minutes, polymerization begins and the solution becomes viscous. Over the next four hours, the temperature is maintained at 48° C. After 3.0 hours of polymerization, an additional 2.0 g of a 1% solution of V-50 is added to the reaction mixture. After 3.5 hours of polymerization (approximately 80% conversion), 0.25 g of vinyltrimethoxysilane is added to the reaction mixture. At four hours after initiation, 4.0 g of a 10% solution of V-50 is added to the dispersion and the reaction is allowed to continue for another 4 hours. After this time, the dispersion is cooled to room temperature, and 5.0 g of adipic acid and 10.0 g of sodium thiosulfate is added. The polymer product has a Brookfield viscosity of 150 cP (#3 spindle, 12 rpm) and a reduced specific viscosity of 18 dl/g at 450 ppm in 1 N NaNO3.
Polymer 5, a 21% polymer solids, 70/30 mole percent acrylamide/diallyldimethyl ammonium chloride VTMS-modified dispersion polymer was synthesized in the following manner.
To a 1500 ml reaction flask fitted with a mechanical stirrer, thermocouple, condenser, nitrogen purge tube, and addition port is added 28.0 g of a 49.4% aqueous solution of acrylamide (Nalco Chemical Company, Naperville, Ill.), 175.0 g of a 63% aqueous solution of diallyldimethyl ammonium chloride (Nalco Chemical Company, Naperville, Ill.), 44.0 g of a 15% aqueous solution of a homopolymer of dimethylaminoethyl acrylate methyl chloride quaternary salt (Nalco Chemical Company, Naperville, Ill.), 0.66 g of sodium formate, 0.44 g of ethylenediaminetetraacetic acid, tetra sodium salt, 220.0 g of ammonium sulfate, 44.0 g sodium sulfate, 0.20 g polysilane antifoam (Nalco Chemical Company, Naperville, Ill.), and 332.0 g of deionized water. The resulting mixture is heated to 42° C. and is stirred at 700 rpm. Upon reaching 42° C., 5.0 g of a 10.0% aqueous solution of 2,2′-azobis[2-(2- imidazolin-2-yl)propane]dihydrochloride (VA-044, Wako Chemicals, Dallas, Tex.) is added to the reaction mixture and a nitrogen purge started. Forty-five minutes after initiator addition, 194.7 g of a 49.4% aqueous solution of acrylamide is added to the reaction mixture over a period of 6 hours. At 4.5 hours after initiator addition (˜80% acrylarnide conversion based on total monomer), 0.26 g of vinyltrimethoxysilane (Huls America, Inc., Bristol, Pa.) is added to the reaction. At 8 hours after the initiator addition, the reaction mixture is cooled to ambient temperature. The product is a smooth milky white dispersion with a bulk viscosity of 520 cP and a reduced specific viscosity of 4.5 dl/g (0.045% solution of the polymer in 1.0 N aqueous sodium nitrate at 30° C.).
Polymer 6, a vinyltrimethoxy silane-modified, 21% polymer solids, 70/30 mole percent acrylamide/diallyldimethyl ammonium chloride dispersion polymer is synthesized following the procedure described in Example 5, except that the vinyltrimethoxysilane is added to the reaction 5.5 hours after initiator addition (˜90% acrylamide conversion based on total monomer). The product is a smooth milky white dispersion with a bulk viscosity of 460 cp and a reduced specific viscosity of 5.1 dl/g (0.045% solution of the polymer in 1.0 N aqueous sodium nitrate at 30° C.).
The polymers synthesized by the methods of Example 1-6 are summarized in Table 1.
Polymer Modified by Late Addition of VTMS
(VTMS levels in ppm based on polymer actives in product)
Polymer Modified Form [VTMS] (ppm) RSV (dL/g)
1 no hydrophobic None 18
2 yes hydrophobic 1667 18
3 yes hydrophobic 667 16
4 yes hydrophilic 1667 18
5 yes hydrophilic 1250 4.5
6 yes hydrophilic 1250 5.1
71 no hydrophilic None 18
82 no hydrophilic None 4.5
1Commercially available 90/10 mole percent AcAm/DMAEA.MCQ copolymer (Nalco Chemical Company, Naperville, IL).
2Commercially available 70/30 mole percent AcAm/DADMAC copolymer (Nalco Chemical Company, Naperville, IL).
Three experimental techniques are utilized to assess the utility of the structurally-modified polymers in papermaking applications. These techniques are detailed below. For the first two techniques, a synthetic alkaline paper furnish is utilized.
The alkaline furnish has a pH of 8.1 and is composed of 80 weight percent cellulosic fiber and 20 weight percent filler diluted to an overall consistency of 0.5% by weight using synthetic formulation water. The cellulosic fiber consists of 60% by weight bleached hardwood kraft and 40% by weight bleached softwood kraft. The filler is a commercial ground calcium carbonate provided in dry form. The formulation water contains 200 ppm calcium hardness (added as CaCl2), 152 ppm magnesium hardness (added as MgSO4), and 110 ppm bicarbonate alkalinity (added as NaHCO3).
The Britt Jar Test uses a Britt CF Dynamic Drainage Jar developed by K. W. Britt of New York University, which generally consists of an upper chamber of about 1 liter capacity and a bottom drainage chamber, the chambers being separated by a support screen and a drainage screen (typically 200 mesh or 76 μm opening). Below the drainage chamber is a flexible tube extending downward equipped with a clamp for closure. The upper chamber is provided with a 2-inch, 3-blade propeller to create controlled shear conditions in the upper chamber. The test is performed according to the following sequence:
0 Commence shear via mixing; add synthetic furnish.
10 Add starch (usually 10 lb/t).
20 Add flocculant to be tested.
30 Open the tube clamp to commence drainage.
60 Stop draining and measure turbidity of filtrate.
Where the beneficial effect of microparticles on polymer performance is evaluated, the following sequence is used:
0 750 Commence shear via mixing; add synthetic furnish.
10 750 Add cationic starch (usually 10 lb/t).
20 2000 Add flocculant to be tested.
50 750 Reduce the shear via mixing speed.
60 750 Add microparticle.
70 750 Open the tube clamp to commence drainage.
100 750 Stop draining.
The starch used is Solvitose N, a cationic potato starch, commercially available from Nalco Chemical Company, Naperville, Ill. The material drained from the Britt Jar (the “filtrate”) is collected and diluted with water to provide a turbidity which can be measured conveniently. The turbidity of such diluted filtrate is then determined in Nephelometric or Formazine Turbidity Units (NTU or FTU). The turbidity of the filtrate is inversely proportional to the papermaking retention performance; the lower the turbidity value (or higher the turbidity reduction), the higher is the retention of filler and/or fines. Therefore the lower the turbidity, the more efficient the flocculant. The turbidity values are determined using a Hach Turbidimeter.
Filler retention for the synthetic alkaline furnish is also determined by gravimetric analysis (500-550° C.) of the filtrate collected.
The size of flocs formed (evaluated by determining changes in the mean chord length) for the synthetic alkaline furnish are measured in-situ using a Focused Beam Reflectance (FBRM) instrument to measure peak mean chord length. The FBRM employed in the following examples is described in U.S. Pat. No. 4,871,251 and Alfano, et al., Nordic Pulp and Paper Research Journal, 13, (2), 159 (1998), and generally consists of a laser source, optics to deliver the incident light to and retrieve the scattered light from the furnish, a photodiode, and signal analysis hardware. Commercial instruments (Model # M100 or M500) are available from Lasentec™, Redmond, Wash.
The experiment consists of taking 300 ml of the desired paper furnish and placing this in the appropriate mixing beaker. Shear is provided to the furnish via a variable speed motor and propeller. The propeller is set at a fixed distance from the probe window to ensure slurry movement across the window. The change in mean chord length of the the furnish relates to papermaking retention performance; the greater the change induced by the treatment, the higher the retention value. Therefore a larger mean chord length number means that the flocculant is more efficient. A typical dosing sequence is shown below.
0 Commence mixing. Record baseline floc size
30 Add cationic starch. Record floc size change.
45 Add flocculant to be tested. Record floc size change.
90 Terminate experiment.
Dissolved Air Flotation Test (DAF)
Samples of dissolved air flotation (DAF) influent are obtained from a Southern United States newsprint deinking mill. Typical jar tests are used to monitor polymer performance. Samples of the deinking influent are stirred at 200 rpm (fast mix) for 3 minutes. A coagulant (alum) is added at the beginning of fast mix and the flocculant during the last 40 seconds of the fast mix. This is followed by a slow mix at 25 rpm for 2 minutes. The samples are allowed to settle for 5 minutes and an aliquot of the upper liquid layer is removed. The turbidity of these aliquots is determined with a HACH DR2000 at 450 nm. The lower the turbidity, the more efficient the flocculant.
The Britt Jar test described above is utilized to obtain the results of Tables 2-4. In all examples, a greater turbidity reduction resulted from use of VTMS-modified dispersion polymer flocculants than with the equivalent dispersion polymer flocculants which are not modified.
Polymer Retention Performance Comparison for Modified versus
Unmodified Dispersion Polymers at 750 rpm (low shear)
Dosage1 Polymer 7 Polymer 4
0.3 69.2 71.5
0.6 78.3 83.2
0.9 82.6 86.9
1pound active per ton solids.
2measured in terms of percent turbidity reduction.
Polymer Retention Performance for Modified versus Unmodified
Dispersion Polymers at 1250 rpm (medium shear)
Dosage1 Polymer 1 Polymer 2 Polymer 7 Polymer 4
0.60 57.1 59.4 57.1 59.4
0.90 62.9 64.7 59.7 62.5
1.20 63.7 72.1 62.3 69.5
Dispersion Polymers at 1500 rpm (high shear)
Dosage1 Polymer 1 Polymer 2 Polymer 3 Polymer 7 Polymer 4
0.60 — — — 50.4 53.3
0.90 52.6 60.6 — — —
1.20 54.2 — 55.3 55.6 63.4
1.80 — — 67.5 55.6 64.3
2.10 65.1 67.8 71.1 — —
The Dissolved Air Flotation test (DAF) is utilized to obtain the results of Table 5. In the tests, the VTMS modified dispersion polymer flocculant provided greater turbidity reduction than the equivalent unmodified polymer flocculent.
Clarification of DAF Influent using Modified and
Unmodified Polymers (performance in terms of
percent turbidity reduction for a polymer dose of 1.6 ppm)
Polymer 8 Polymer 5 Polymer 6
69.23 70.9 71.4
Clarification of DAF Influent using
Unmodified and Modified polymers
Polymer Dose1 (ppm) Polymer 8 Polymer 5 Polymer 6
0.8 67.89 69.23 68.56
1.6 76.59 78.93 77.26
1In the presence of 150 ppm alum.
The foregoing results demonstrates that a modified polymer shows improved performance over that of an unmodified polymer having comparable solution properties.
AcAm/DMAEA.MCQ (9:1) inverse emulsion polymers modified with MBA at different conversions are synthesized in the following manner:
An aqueous monomer phase is made-up by stirring together 364.37 g of a 49.6% aqueous solution of acrylamide (AcAm, Nalco Chemical Co., Naperville, Ill.), 178.33 g of water, 9.00 g of adipic acid, 27.00 g of NaCl, and 0.80 g of a 50% aqueous solution of NaOH. The components are stirred until dissolved. To the resulting solution is added 67.90 g of a 80.3% solution of dimethylaminoethylacrylate methyl chloride quaternary salt (DMAEA.MCQ, CPS Chemical Co.; Old Bridge, N.J.) and 0.09 g of EDTA.4 Na+ (ethylenediamine tetraacetic acid, tetra sodium salt, Van Waters & Rogers, Geismar, La.). The pH of the resulting mixture is 3.9.
An oil phase is prepared by heating a mixture of 234.29 g of paraffinic oil (Isopar M, Exxon, Houston, Tex.), 13.50 g of Span-80 and 4.50 g of Tween-61 until the surfactants dissolve (54-57° C.). The oil phase is charged into a 2 L reactor and heated to 45° C. With vigorous stirring (900 rpm, 10 mm rod with a teflon paddle at the base and 6-blade turbine mounted 3-inches from the bottom), the monomer phase is added over 2 minutes. The resulting mixture is stirred for 30 minutes.
To the water-in-oil emulsion is added 0.200 g of AIBN and 0.027 g of AIVN. The polymerization is carried out under a N2 atmosphere at 45° C. for 4 hours, then 70° C. for one hour. The percent conversion is estimated by density change. A density of 0.9855 g/ml is measured for the starting emulsion, and a density of 1.0217 g/ml for the final emulsion. At different densities of the emulsion (related to percent monomer conversion), 4.72 g of a 200 ppm solution of methylene bisacrylamide (4 ppm based on monomer, MBA, Aldrich Chemical Company, Milwaukee, Wis.) is added to the reaction mixture. Polymers prepared using the foregoing procedure are shown in Table 7. Polymer 14 is representative of those polymers disclosed in EP 202,780. For these emulsion polymers synthesized at 26 percent actives, the highest reduced specific viscosity is obtained for polymers where MBA is added at 75-85% conversion.
Representative 90/10 mole % AcAm/DMAEA.MCQ
Copolymers Modified Using MBA, Prepared
According to the Method of Example 8
Polymer [MBA], ppm % Conversion RSV, (dl/g)
9 0 NA 27.0 ± 2.8
10 4 75-85 31.9 ± 1.4
11 4 65 26.3
12 4 46 22.0
13 4 17 16.0
141 4 0 13.0
1Polymer synthesized as described in EP 202,780.
Reduced Specific Viscosity of Modified Polymers
(90/10 mole % AcAm/DMAEA · MCQ)
MBA Concentration Added At
Polymer (ppm) % Conversion RSV, (dl/g)
9 0 NA 26.8
10 4 82 31.0
151 2 0 19.3
161 6 0 9.4
Table 8 illustrates that when the cross-linking agent is present at the beginning of polymerization, the resulting polymers show a drop in reduced specific viscosity even at very low MBA concentrations. In contrast to the polymers disclosed in EP 202,780, the polymers modified as described herein have a greater viscosity, which is advantageous for a flocculant.
Polymers modified with MBA according to the procedure described in Example 8 are compared to polymers conventionally cross-linked. It is known to those skilled in the art that conventionally, the cross-linker is added at the beginning of the polymerization. We have discovered that when the cross-linker is added is of critical importance to the flocculating ability of the resultant polymer. Tables 8-15 illustrate the surprising superiority of polymer 10, modified by late addition of cross-linker over polymer 14 that is conventionally cross-linked and polymer 9 that is unmodified. Tables 9, 10, 12, 13, 15 and 16 contain results of Britt Jar tests, and Tables 11 and 14 contain results of FBRM tests.
Retention Performance for Modified and Unmodified Polymers
Dose1 Polymer 9 Polymer 10 Polymer 14
0.14 58.6% 59.8% NA
0.28 69.1% 78.1% 71.9%
0.56 84.3% 87.2% 82.9%
1Pounds active per ton of slurry solids
2Percent turbidity reduction indicative of total retention; synthetic alkaline furnish.
Dose1 Polymer 9 Polymer 10
0.25 55.9% 68.8%
1.00 87.5% 95.1%
2.00 87.6% 99.9%
1Pounds active per ton of slurry solids.
2Percent increase in filler retention; synthetic alkaline furnish.
Flocculation Performance of Modified and Unmodified Polymers
Determined using FBRM
0.25 36.0 32.1
0.50 44.1 35.5
1.00 45.2 46.0
2.00 46.2 57.2
2Change in peak mean chord length; synthetic alkaline furnish.
% Turbidity Reduction1
Polymer 0.5 lb/t 1.0 lb/t
14 51.9 66.3
13 54.3 71.4
12 56 70.8
11 66 79.2
10 62 78.7
9 60.3 78
1Furnish from a southern paper mill.
1.0 18.9% 20.4%
2.0 36.5% 40.2%
4.0 55.0% 64.1%
2Percent turbidity reduction; at a midwestern paper mill.
Determined using FBRM (Model M100)
0.25 48.5 58.7
0.50 60.0 69.5
1.00 73.5 94.4
2Change in peak mean chord length; furnish from a midwestern paper mill.
The data in the above tables clearly show that the structurally-modified polymers are more efficient and effective retention aids than the linear controls for synthetic alkaline furnish and mill furnishes.
The following two Britt Jar test experiments demonstrate that the polymers of this invention modified by late addition of cross-linkers have better retention performance than conventional treatments when used together with bentonite in a microparticle program on a synthetic alkaline furnish. The results are detailed in Tables 15 and 16.
Performance of Modified and Unmodified Polymers
in Conjunction with Microparticles
Bentonite dose
(pounds active per ton of Retention,
Polymer1 slurry solids) %
9 1.0 81.5
10 1.0 87.5
172 1.0 78.1
1Treated at 1.5 pounds active per ton of slurry solids; synthetic alkaline furnish.
2Cationic flocculant FO 4198, available from SNF, St. Etienne, France. (cationic, branched dry polymer described in US 5,393,381).
Table 16 shows the results for a polymer/microparticle combination, where the microparticle is either bentonite or borosilicate, available from Nalco Chemical Co. of Naperville, Ill. under the tradename UltraXol®. For the sake of clarity, modified polymers of this invention are offset to the right in the first column, for comparison to conventional treatments which are offset to the left.
Polymer/Dose1 Microparticle/Dose1 Retention, %
9/0.5 bentonite/3.0 72.8
9/1.0 bentonite/1.0 77.1
9/1.0 bentonite/3.0 86.4
10/0.5 bentonite/3.0 79.8
10/1.0 bentonite/1.0 88.0
10/1.0 bentonite/3.0 95.1
14/0.5 bentonite/3.0 63.3
14/1.0 bentonite/3.0 80.4
10/0.5 borosilicate/1.0 79.5
10/1.0 borosilicate/1.0 93.9
1Pounds active per ton of slurry solids; synthetic alkaline furnish.
Table 16 demonstrates that the modified polymers of this invention (Polymer 10) performs better than the commercially available flocculant (Polymer 9) in a microparticle program of bentonite or borosilicate. Polymers synthesized with cross-linking agent added upfront (Polymer 14) also show inferior performance to the modified polymer of this invention.
CHAIN TRANSFER AGENT MODIFIED POLYMERS EXAMPLE 11
An AcAm/DMAEA.MCQ (90:10) copolymer lattice modified by late addition of sodium formate at high conversion (Polymer 18), is synthesized in the following manner.
An aqueous monomer phase is made-up by stirring together 484.12 g of a 49.4% aqueous solution of acrylamide (Nalco Chemical Co., Naperville, Ill.), 20.25 g of water, 9.00 g of adipic acid, 27.00 g of NaCl, and 0.27 g of a 50% aqueous solution of NaOH. The components are stirred until dissolved. To the resulting solution is added 90.30 g of a 80.2% solution of dimethylaminoethylacrylate methyl chloride quaternary salt (DMAEA.MCQ, CPS Chemical Co.; Old Bridge, N.J.) and 0.18 g of EDTA.4 Na+ (Van Waters & Rogers, Geismar, La.). The pH of the resulting mixture is 3.8.
An oil phase is prepared by heating a mixture of 243.00 g of paraffinic oil (Isopar M, Exxon, Houston, Tex.), 8.92 g of Span-80 and 13.58 g of Tween-61 until the surfactants dissolve (54-57° C.). The oil phase is charged into a 2 L reactor and heated to 45° C. With vigorous stirring (900 rpm, 10 mm rod with a teflon paddle at the base and 6-blade turbine mounted 3-inches from the bottom), the monomer phase is added over 2 minutes. The resulting mixture is stirred for 30 minutes.
To the water-in-oil dispersion is added 0.200 g of AIBN and 0.027 g of AIVN. The polymerization is carried out under a N2 atmosphere at 45° C. for 4 hours, then 70° C. for one hour. At a conversion of 80% (estimated by density change), 8.29 g of a 38% solution of sodium formate (2000 ppm based on monomer, Van Waters & Rogers, Geismar, La.) is added to the reaction mixture. The resulting polymer has an RSV of 30.9 dl/g (1M NaNO3, 450 ppm, 30° C.). An unmodified polymer polymerized without late addition of sodium formate (Polymer 19, Table 17) is synthesized in a similar manner. These polymers are characterized in Table 17.
Representative Cationic AcAm/DMAEA-MCQ Copolymers
Modified Using Sodium Formate
(prepared according to the method of Example 11)
Mole % Added at RSV
Polymer DMAEA-MCQ ppm (% Conversion) (dl/g)
18 10 2000 82 30.9
19 10 0 — 17.8
To those skilled in the art, formic acid or metal salts thereof, are known as efficient chain transfer agents to limit the molecular weight and viscosity of acrylamide based polymers (for example, U.S. Pat. No. 4,307,215). It has also been reported (U.S. Pat. No. 4,307,215 at col., line 54) that addition of chain transfer agent after polymerization has no effect on molecular weight. However, as shown in Tables 17, 19 and 22, we have found that adding chain transfer agents at different polymerization stages gives polymers with increased reduced specific viscosity over unmodified analogs. Tables 18 and 20 illustrate that the modified polymers are superior to the unmodified control polymers in paper retention tests.
Dose1 Polymer 19 Polymer 18
0.25 61.4% 71.6%
0.50 72.2% 86.6%
1.00 85.2% 93.5%
2Percent turbidity reduction; synthetic alkaline furnish.
An AcAm/DMAEA.MCQ (90:10) copolymer lattice modified by late addition of sodium hypophosphite at high conversion (Polymer 20), is synthesized in the following manner.
An aqueous monomer phase is made-up by stirring together 281.96 g of acrylamide (Mitsubishi, Japan), 194.00 g of water, 9.00 g of adipic acid, 27.00 g of NaCl, and 0.27 g of a 50% aqueous solution of NaOH. The resulting mixture is stirred for 10 minutes. To the resulting suspension is added 107.54 g of a 79.4% solution of dimethylaminoethylacrylate methyl chloride quaternary salt (DMAEA.MCQ, CPS Chemical Co.; Old Bridge, N.J.) and 0.18 g of EDTA.4 Na+ (Van Waters & Rogers, Geismar, La.). A solution is obtained by heating the suspension to 35° C. while stirring for about 10 minutes. The pH of the resulting mixture is 3.8.
An oil phase is prepared by heating a mixture of 252.00 g of paraffmic oil (Isopar M, Exxon, Houston, Tex.), 15.79 g of Span-80 and 11.21 g of Tween-61 until the surfactants dissolve (54-57° C.). The oil phase is charged into a 2 L reactor and heated to 42° C. With vigorous stirring (900 rpm, 10 mm rod with a teflon paddle at the base and 6-blade turbine mounted 3-inches from the bottom), the monomer phase is added over 2 minutes. The resulting mixture is stirred for 30 minutes.
To the water-in-oil emulsion is added 0.200 g of AIBN and 0.027 g of AIVN. The polymerization is carried out under a N2 atmosphere at 42° C. for 2 hours. The reaction mixture is then cooled to 35° C., 0.85 g of a 10% aqueous solution of 2,2′-azobis[2-(2-imidazolin-2-yl)] dihydrochloride (VA-044, Wako Chemical Co.) is added, and the reaction continued for 19 hours. At a conversion of 75% (estimated by density change, 100 minutes), 1.84 g of a 20% solution of sodium hypophosphite monohydrate (1000 ppm based on monomer, J. T. Baker, Phillipsburg, N.J.) is added to the reaction mixture. The resulting polymer has an RSV of 27.7 dl/g (1M NaNO3, 450 ppm, 30° C.).
An unmodified polymer polymerized without late addition of sodium hypophosphite (Polymer 21) is synthesized in a similar manner, except, VA-044 is omitted from the formulation and polymerization is performed using a 42-50° C. temperature gradient over 2.5 hours, then at 70° C. for 1 hour. Polymer 21 has an RSV of 13.6 dl/g (1M NaNO3, 450 ppm, 30° C.).
Representative Cationic AcAm/DMAEA.MCQ Latex Copolymers
Modified Using Sodium Hypophosphite
(prepared according to the method of Example #12)
Chain Added at
Mole % Transfer Level % con- RSV
Polymer DMAEA.MCQ Agent (ppm) version (dl/g)
20 10 Sodium 1,000 75 27.7
21 10 — — — 13.6
FBRM Measurement of Polymers 9, 20 and 21 using the
Dosing Sequence in Table 21
(Lasentec M500)
Dose1 Polymer 9 Polymer 21 Polymer 20
0.25 4.2 (±0.3) 1.6 (±1.2) 5.8 (±1.8)
0.50 7.7 (±0.7) 3.8 (±0.9) 10.0 (±1.3)
1.00 13.3 (±1.4)  7.8 (±2.0) 15.8 (±2.0)
2Change in peak mean chord length; synthetic alkaline furnish
Dosing Sequence for Table 20
20 Add flocculant to be tested. Record floc size change.
60 Terminate experiment.
An AcAm/sodium acrylate (70:30) copolymer lattice modified by late addition of sodium hypophoshite at high conversion (Polymer 22), is synthesized in the following manner.
An aqueous monomer phase is made-up as follows. A 50% aqueous solution of NaOH (92.0 g) is addes dropwise to a cold solution of acrylamide (376.8 g of a 50.8% aqueous solution), 166.5 g of water, and 83.0 g of glacial acrylic acid until a solution pH of 8.3 is obtained. A 2% solution of EDTA.4Na+ Waters & Rogers, Geismar, La.) is added to the resulting mixture.
An oil phase is prepared by heating a mixture of 252.8 g of paraffinic oil (Escaid-110), 12.2 g of Span-80 and 7.3 g of Tween-61 until the surfactants dissolved (54-57° C.). The oil phase is charged into a 2 L reactor and heated to 45° C. With vigorous stirring (900 rpm, 10 mm rod with a teflon paddle at the base and 6-blade turbine mounted 3-inches from the bottom), the monomer phase is added over 2 minutes. The resulting mixture is stirred for 30 minutes.
To the water-in-oil emulsion is added 0.51 g of AIBN. The polymerization is carried out under a N2 atmosphere at 45° C. for 4 hours, then at 70° C. for 1 hour. At a conversion of 70 (estimated by density change, 90 minutes), 4.0 g of a 0.5% solution of sodium hypophosphite monohydrate (67 ppm based on monomer, J. T. Baker, Phillipsburg, N.J.) is added to the reaction mixture. The resulting polymer has an RSV of 50.7 dl/g (1M NaNO3, 450 ppm, 30° C.).
An unmodified polymer polymerized without late addition of sodium hypophosphite (Polymer 23) is synthesized in a similar manner.
Representative Anionic AcAm/Sodium Acrylate Latex Copolymers
Modified Using Chain-Transfer Agents
(prepared according to the method of Example 13)
Mole % Chain Added at
Sodium transfer Level % con- RSV
Polymer acrylate agent (ppm) version (dl/g)
22 30 Sodium 67 70 50.7
23 30 — — — 20.0
An aqueous dispersion of acrylamide/acrylic acid copolymer (70/30 mole %), that contains sodium formate (CTA) in the initial monomer phase and is modified by late addition of sodium hypophosphite at high conversion (Polymer 24), is synthesized in the following manner.
A monomer reaction solution is prepared by combining 334.6 g deionized water, 65.0 g sodium sulfate, 85.0 g ammonium sulfate, 1.4 g sodium formate, 326.3 g of a 48.9% aqueous solution of acrylamide, 0.40 g of the tetrasodium salt of ethylene diamine tetracetic acid, 69.3 g acrylic acid, 13.5 g of a 50% aqueous solution of sodium hydroxide, and 100.0 g of a 12% aqueous solution of poly(acrylamidomethylpropanesulfonic acid/methacrylic acid) copolymer (Nalco Chemical Company, Naperville, Ill.). The pH of the resulting mixture is 4.0. The monomer reaction solution is heated to 35° C. with thorough mixing. To the homogenous monomer reaction solution is added 1.0 g of a 1% aqueous solution of VA-044 (2,2′-Azobis (N,N′dimethyleneisobutyramidine)dihydrochloride), Wako Chemicals USA, Inc.; Richmond, Va.). The polymerization is carried out under N2 atmosphere at 35° C. with thorough mixing. After a total reaction time of 4 hours, 1.0 g of a 1% aqueous solution of VA-044 is added to the reaction mixture. At a monomer conversion of 80%, 0.57 g of a 10% aqueous solution of sodium hypophosphite monohydrate (250 ppm based on monomer) is added to the reaction mixture. After a total reaction time of 8 hours, 2.0 g of a 10% aqueous solution of VA-044 is added, and the reaction continued for another 4 hours (for a total reaction time of 12 hours). The product of this reaction is a milky white liquid having a RSV of 30 dl/g (1 M NaNO3, 450 ppm, 30° C.).
An unmodified polymer polymerized without late addition of sodium hypophosphite (Polymer 25) is synthesized in a similar manner. The unmodified polymer has a RSV of 34 dl/g (1M NaNO3, 450 ppm, 30° C.).
Representative Anionic Acrylamide/Acrylic Acid Dispersion
Polymers Modified Using Chain-Transfer Agents
(prepared according to the method of Example 14)
Mole % Level Added
Acrylic Chain transfer (ppm at % RSV
Polymer acid agent BOM) conversion (dL/g)
24 30 Sodium 250 80 30
25 30 — — — 34
Retention and Drainage Performance of Polymers 24 and 25
% Turbidity Reduction2
Dose1 Polymer 24 Polymer 25
0.25 69.6 59.2
0.5 78.0 69.3
1.00 83.7 78.5
1Pounds polymer active per ton of slurry solids.
2Britt Jar testing, synthetic alkaline furnish.
POLYMERS MODIFIED WITH COMBINATIONS OF CROSSLINKER & CHAIN TRANSFER AGENTS EXAMPLE 15
An AcAm/DMAEA-MCQ (90:10) copolymer lattice modified with a chain-transfer and cross-linking agent added during polymerization (Polymer 26) is synthesized as follows.
An aqueous monomer phase is made-up by stirring together 364.37 g of a 49.6% aqueous solution of acrylamide (Nalco Chemical Co., Naperville, Ill.), 175.20 g of water, 9.00 g of adipic acid, 27.00 g of NaCl, and 0.80 g of a 50% aqueous solution of NaOH until the components are in solution. To the resulting solution is added 67.90 g of a 80.3% solution of dimethylaminoethylacrylate methyl chloride quaternary salt (DMAEA.MCQ, CPS Chemical Co.; Old Bridge, N.J.) and 0.09 g of EDTA.4 Na+ (Van Waters & Rogers, Geismar, La.). The pH of the resulting mixture is 3.8.
An oil phase is prepared by heating a mixture of 234.29 g of paraffmic oil (Isopar M, Exxon, Houston, Tex.), 13.5 g of Span-80 and 4.5 g of Tween-61 until the surfactants dissolve (54-57° C.). The oil phase is charged into a 2 L reactor. With vigorous stirring (900 rpm, 10 mm rod with a teflon paddle at the base and 6-blade turbine mounted 3-inches from the bottom), the monomer phase is added over 2 minutes. The resulting mixture is stirred for 30 minutes and heated to 45° C.
To the water-in-oil emulsion is added 0.200 g of AIBN and 0.027 g of AIVN. The polymerization is carried out under a N2 atmosphere at 45° C. for 4 hours, then 70° C. for one hour. A 5 solution of 0.0059 g methylene bisacrylamide (25 ppm, Aldrich Chemical Company, Milwaukee, Wis.) and 0.1882 g sodium formate (800 ppm, Van Waters & Rogers, Geismar, La.) in 5.87 g water is added to the reaction mixture at a constant rate from 54-80% monomer conversion. The resulting polymer has a RSV of 22.7 dl/g (1M NaNO3, 450 ppm, 30° C.).
An AcAm/DMAEA.MCQ (1:1) copolymer lattice modified with a chain-transfer and cross-linking agent added during polymerization (Polymer 27) is synthesized in the following manner.
An aqueous monomer phase is made-up by stirring together 130.1 lb of a 49.5% aqueous solution of acrylamide (Nalco Chemical Co., Naperville, Ill.), 180.6 lb of water, 8.0 lb of adipic acid, 24.0 lb of NaCl, and 0.7 lb of a 50% aqueous solution of NaOH until the components are in solution. To the resulting solution is added 219.5 lb of a 80.0% solution of dimethylaminoethylacrylate methyl chloride quaternary salt (DMAEA.MCQ, CPS Chemical Co.; Old Bridge, N.J.) and 0.2 lb of EDTA.4 Na+ (Van Waters & Rogers, Geismar, La.). The pH of the resulting mixture is 3.8.
An oil phase is prepared by heating a mixture of 208.0 lb of paraffinic oil (Escaid 110, Exxon, Houston, Tex.), 7.2 lb of Span-80 and 15.2 lb of Tween-61 until the surfactants dissolved (54-57° C.) in a 100-gal reactor. A water-in-oil dispersion is made by adding the monomer phase to the oil phase and stirring for 30 minutes. To the water-in-oil dispersion is added 0.26 lb of AIBN and 0.04 lb of AIVN. The polymerization is carried out under a N2 atmosphere at 42° C. A solution of 0.006 lb methylene bisacrylamide (25 ppm, Aldrich Chemical Company, Milwaukee, Wis.) and 0.192 lb sodium formate (800 ppm, Van Waters & Rogers, Geismar, La.) in 6.00 lb water is added to the reaction mixture at a constant rate from 11-82% monomer conversion. When the reaction appeared complete, the reaction mixture is heated at 75° C. for 1 hour. After cooling 14.4 lb of Alfonice 14-12 Nalco 60 is added to the dispersed polymer. Polymer 27 has a RSV of 8.8 dl/g (1M NaNO3, 450 ppm, 30° C.).
Polymer 28 (Table 25) is synthesized in a similar manner.
Representative Cationic AcAm/DMABA.MCQ Copolymers Modified
Using Combinations of Chain Transfer Agent
and Cross-linking Agent
Mole % [MBA] [NaF] Added at RSV
Polymer DMAEA.MCQ ppm ppm (% Conversion) (dl/g)
26 10 25 800 54-82 22.7
27 50 25 800 11-82 8.8
28 50 25 800 6-49 6.2
291 50 0 0 — 21.0
150:50 mole percent AcAm/DMAEA.MCQ latex copolymer (Nalco Chemical Co., Naperville, IL).
To further demonstrate the superiority of the modified polymers, they are compared to polymers prepared according to the procedure of EP 374,458 as follows.
The three 10 mole % cationic copolymers of DMAEA.MCQ with acrylamide (Polymers 30, 31 and 32) shown in Table 26 are synthesized according to the procedure outlined in EP 374,458 at page 6, line 53, example 5 B. The polymers contain varying amounts of a branching (or cross-linking) and chain transfer agents.
Representative Polymers Prepared as Described in EP 374,458
Branching or Cross-
Chain transfer agent linking agent (Methylene Solubility
Polymer (1.5% Isopropanol) % bisacrylamide), ppm Quotient, %
30 3 8 33
31 9 8 36
32 18 8 52.5
The retention performance of Polymers 31 and 32, representative of the polymers described in EP 374,458, is compared to a modified polymer of this invention in Table 27 (Polymer 10). The results are presented in Table 27.
Comparative Retention Performance of Modified
and Unmodified Polymers
Polymeric Treatments
Dose1 Polymer 31 Polymer 32 Polymer 10
0.50 62.9% 59.9% 87.2%
1.00 73.7% 68.6% 93.3%
1Pounds active per ton of slurry solids, synthetic alkaline furnish.
2Percent turbidity reduction.
As shown in Table 27, as a flocculant alone, the polymers of EP 374,458 show significantly inferior retention performance to the modified polymers of this invention. The retention preformance of the polymers of EP 374,458 and a representative modified polymer of this invention in conjunction with bentonite in a microparticle program is shown in Table 28. This data shows the superiority of modified polymers of this invention over those disclosed in EP 374,458.
Comparative Britt Jar Retention Performance
(Turbidity reduction) of Modified and Unmodified Polymers
Treatment/Dose1 Bentonite dose1 Retention, %
10/1.0 1.0 88.0
31/1.0 1.0 61.6
32/1.0 1.0 57.8
10/1.0 3.0 95.1
31/1.0 3.0 65.1
32/1.0 3.0 63.5
Polymer 33, a polymer of 20% polymer solids, 65/25/10 mole percent AcAm/DMAEA.BCQ/DMAEA.MCQ dispersion is synthesized in the following manner.
A 1500 ml reaction flask is fitted with a mechanical stirrer, thermocouple, condenser, nitrogen purge tube, and addition port. To this reactor is added 139 g of a 49.4% aqueous solution of acrylamide (Nalco Chemical Co., Naperville, Ill.), 134 g of dimethylaminoethylacrylate benzyl chloride quaternary salt (71.5% aqueous solution, Nalco Chemical Co., Naperville, Ill.), 36 g of dimethylaminoethylacrylate methyl chloride quaternary salt (80% aqueous solution, NCF Manufacturing, Riceboro, Ga.), 10 g of glycerin, 56 g of the copolymer of dimethylaminoethylacrylate benzyl chloride quaternary salt and diallyldimethylammonium chloride (15% aqueous solution, Nalco Chemical Co., Naperville, Ill.), 10 g of the homopolymer of dimethylaminoethylacrylate methyl chloride quaternary salt (15% aqueous solution, Nalco Chemical Co., Naperville, Ill.), 0.25 g of ethylenediaminetetraacetic acid, tetra sodium salt, 152 g of ammonium sulfate and 380 g of deionized water. The mixture is then heated to 48° C. while stirring at 700 rpm. After reaching 48° C., 2.0 g of a 1.0% aqueous solution of 2,2′-azobis(2-amidinopropane) dihydrochloride (V-50, Wako Chemicals of Dallas, Tex.) is added to the reaction mixture and the temperature is maintained at 48° C. throughout the reaction. Forty five minutes into the reaction (˜10% monomer conversion) 2.5 g of a 10% aqueous solution of sodium formate is added to the reaction. Two hours after initiation 3.0 g of a 1.0% aqueous solution of 2,2′-azobis(2-amidinopropane) dihydrochloride is added to the reaction, and at four hours 4.0 g of a 10% aqueous solution of 2,2′-azobis(2-amidinopropane) dihydrochloride is added. At eight hours the reaction is returned to ambient temperature and 59.9 g of sodium sulfate, and 11.9 g acetic acid are added. The resulting product is a smooth milky white dispersion with a bulk viscosity of 100 cP having a RSV of 10.2 dl/g (0.125 N NaNO3 solution at 0.045% polymer).
Polymer 34 is prepared according to the procedure of Example 18, except that MBA is added instead of sodium formate. At 80% monomer conversion, 2.0 g of a 0.1% aqueous methylene bisacrylamide solution is added. The resulting product is a smooth milky white dispersion having a bulk viscosity of 100 cP and a RSV of 9.5 dl/g (0.045% polymer in 0.125 N NaNO3 solution).
Polymer 35 is prepared according to the procedure of Example 19, except sodium formate (2.5 g of 10% aqueous solution) is added to the monomer (0% conversion), and no methylene bisacrylamide is added. The resulting product is a smooth milky white dispersion having a bulk viscosity of 100 cP and a RSV of 12.1 dl/g (0.045% polymer in 0.125 N NaNO3 solution).
Polymer 36 is prepared according to the procedure of Example 20, except that 2.0 g of a 0.1% aqueous solution of methylene bisacrylamide is added at 80% conversion. The resulting product is a smooth milky white dispersion having a bulk viscosity of 100 cP and a RSV of 12.0 dl/g (0.045% polymer in 0.125 N NaNO3 solution).
A 10/90 mole % DMAEA.MCQ/AcAm dispersion polymer with methylenebisacrylamide and sodium formate added late in the polymerization (polymer 37) is prepared according to the method of Example 4, except that the amount of deionized water in the formula is reduced by 10.0 g, and instead of vinyltrimethoxysilane, a solution containing 0.0015 g of methylenebisacrylamide, 0.075 g sodium formate and 9.9235 g of deionized water is fed to the polymerization over 90 minutes, beginning at 1.5 hours after initiation. The resulting polymer product has a Brookfield viscosity of 300 cP (#3 spindle, 12 rpm) and a RSV of 18.5 dl/g at 450 ppm in 1 M NaNO3.
Cationic Dispersion Polymers Modified with Cross-linking
agent and Chain Transfer Agents
DMAEA· DMAEA· Na Na MBA
AcAm MCQ BCQ formate formate MBA added RSV
Polymer (mole %) (mole %) (mole %) (ppm) added at (ppm) at (dl/g)
37 90 10 — 500 1.5-3 10 1.5-3 18.5
33 65 10 25 1275 ˜10% 0 NA 10.2
34 65 10 25 1275 ˜10% 10 ˜80% 9.5
38 65 10 25 500 6-41% 10 6-41% 16.2
35 65 10 25 1000 0 0 NA 12.1
36 65 10 25 1000 0 10 ˜80% 12
391 65 10 25 0 NA 0 NA 18
402 65 20 15 0 NA 0 NA 18
41 65 20 15 1275 ˜10% 10 t = 3 hr 16.3
1Available from Nalco Chemical Company, Naperville, IL.
2Available from Derypol, S. A., Barcelona Spain.
Retention Performance of Modified and Unmodified Polymers
(in terms of percent turbidity reduction)
lbs/ton Polymer 7 Polymer 37
0.3 66.3 70.9
0.6 78.5 81
1 88.8 89.5
High Shear Test for Dewatering
To illustrate that polymers prepared according to the procedure of Example 17 are less efficient than the structurally-modified polymers disclosed herein, some comparative testing is done as follows.
The polymer at the desired concentration is added to 200 ml of sludge from a Midwestern municipal facility and mixed using the Britt Jar impeller at 1200 rpm for 1 or 2 seconds depending on the sludge. The conditioned sludge is then poured through a belt filter press filter medium. The amount of water drained in 10 seconds is taken as a measure of the polymer performance, and a larger amount of drainage indicates better dewatering capabilities.
The sludge dewatering performance of the modified polymers are compared to their unmodified counterparts in Tables 31-34. For each example, higher drainage is obtained with the polymers modified according to the procedures described herein than with the equivalent unmodified polymer.
Ten Second Free Drainage
Drainage, (ml)
Dose, (ppm) Polymer 29 Polymer 28
51 44 72
Ten Second Free Drainage Results
Dose, (ppm) Polymer 39 Polymer 33 Polymer 34 Polymer 38
58 68 78 74
68 72 80 86 86
77 80 84 90 82
Ten Seconds Free Drainage Results
Dose, (ppm) 39 36
113 52 58
122 54 72
131 66 74
140 60 74
Dose (ppm) 39 36
59 48 78
Procedure for Coal Refuse Slurry Laboratory Cylinder Seffling Test
Comparative flocculation preformance of an acrylamide/acrylic acid copolymer (70:30 mole %) modified by late addition of sodium hypophosphite (Polymer 24) and the corresponding unmodified polymer (Polymer 25) in a mining applications is done as follows.
A 5-gallon sample of coal refuse slurry is stirred constantly to ensure that the slurry is well dispersed. The slurry is then transferred to 500-ml graduated cylinders. Masking tape is placed on each of the 500-ml cylinders adjancent to the cylinder graduation marks. The initial level of the coal refuse slurry at time equal to zero (which is at the 500-ml mark of the graduated cylinder) is marked on the masking tape. Prior to each test the 500 ml-cylinder containing the coal refuse slurry is inverted several times to disperse any settled solids. The cylinder is then quickly dosed with the desired amount of a 0.12% polymer actives solution (flocculant) and inverted 4 times. The cylinder is then returned to the upright position and a timer is started. The position of the solids interface is monitored as a function of time (in seconds) by marking the level of the solids interface on the masking tape at the appropriate time interval. When the rate of descent of the solid interface begins to slow down the marking of the masking tape is ended. The settling rate (in inches/minute) of the coal refuse slurry for the free-fall region is calculated by dividing the distance of the solid interface from the initial level (in inches) by the elapsed time (in seconds). A faster settling rate indicates better performance
Flocculation Performance of Polymers 24 and 25
Settling Rate (in/min)
Dose (ml)1 Polymer 24 Polymer 25
7 5.4 2.6
9 8.1 4.2
1ml of a 0.12% polymer actives dispersion.
A 22.7% polymer solids, 70/30-mole percent acrylamide/acrylic dispersion polymer (Polymer 42) is synthesized in the following manner.
To a 1500 ml reaction flask fitted with a mechanical stirrer, thermocouple, condenser, nitrogen purge tube, addition port and heating tape is added a solution prepared by combining 356.6 g of deionized water, 64 g sodium sulfate, 84 g ammonium sulfate, 2.8 g sodium formate, 85.0 g of a 16% aqueous solution of poly(acrylamidomethylpropanesulfonic acid/methacrylic acid) copolymer (Nalco Chemical Company, Naperville, Ill.) 329.6 g of a 48.4% aqueous solution of acrylamide (Nalco Chemical Company, Naperville, Ill.), 0.40 g of the tetrasodium salt of ethylene diamine tetracetic acid, 69.3 g acrylic acid (Rohm and Haas Texas, Inc., Deer Park, Tex.), and 4.0 g of a 50% aqueous solution of sodium hydroxide. The pH of the resulting mixture is 3.6. The monomer reaction solution is heated to 35° C. with thorough mixing. To the homogenous monomer reaction solution is added 1.0 g of a 1% aqueous solution of VA-044 (2,2′-Azobis (N,N′-dimethyleneisobutyramidine) dihydrochloride), Wako Chemicals USA, Inc., Richmond, Va.). The polymerization is carried out under N2 atmosphere at 35° C. with thorough mixing. After a total reaction time of 6 hours, 2.0 g of a 1% aqueous solution of VA-044 is added to the reaction mixture. The reaction mixture is kept at 35° C. overnight. The next day, 2.0 g of a 10% aqueous solution of VA-044 is added, and the reaction temperature is maintained for another 2 hours before the reaction mixture is cooled and removed from the reactor. The product of this reaction is a milky white liquid (700 cP., RSV of 33.7 dl/g (1 M NaNO3, 450 ppm, 30° C.).
A 22.7% polymer solids, 70/30 mole percent acrylamide/acrylic acid dispersion polymer modified with sodium formate (Polymer 43) is synthesized according to the procedure of Example 25. After a total 7 hours of reaction time (81% conversion), 2.8 g of sodium formate is added to the reaction mixture. The polymerization is then continued and finished as described in Example 25. The product of this reaction is a milky white liquid (570 cP., RSV of 30.8 dl/g in 1 M NaNO3, 450 ppm, 30° C.).
Flocculation Performance of Modified and Unmodified
Anionic Dispersion Polymers
Dose1 Polymer 42 Polymer 43
0.25 44 56
0.50 59 63
1.0 69 81
1.5 73 95
1Pounds polymer actives per ton of slurry solids.
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Classificatie in de VS 526/78, 525/329.4, 525/329.8, 525/329.9, 526/82, 525/329.7, 525/313, 525/244
Internationale classificatie C08F2/10, C02F1/56, C08F2/38, C08F265/04, C08F2/44, C08F265/10, C02F11/14, C08F265/00, C08J3/24, B01D21/01
Coöperatieve classificatie C08F265/10, C08F265/04, C08F2/10, B03D1/1431
Europese classificatie B03D1/14D, C08F265/10, C08F2/10, C08F265/04
23 okt 2000 AS Assignment
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:WHIPPLE, WESLEY L.;JOHNSON, CATHY C.;GUDDENDORF, TRACEY M.;AND OTHERS;REEL/FRAME:011257/0569;SIGNING DATES FROM 20000906 TO 20001017
21 april 2006 AS Assignment