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EP-4739717-A2 - PREPARATION OF A HIGH REACTION TEMPERATURE DPAM HAVING IMPROVED STANDARD VISCOSITY AND WATER SOLUBILITY

EP4739717A2EP 4739717 A2EP4739717 A2EP 4739717A2EP-4739717-A2

Abstract

The present invention generally relates to compositions and methods for preparation of high reaction temperature dry polyacrylamide (DPAM) polymers. In particular, the disclosure provides methods for adiabatic redox initiated free-radical polymerization of reaction mixtures comprising at least acrylamide monomers, optional free-radical scavenger stabilizers, azo initiators, and redox initiators under pH and initial temperature conditions that allow heat of polymerization to increase reaction temperatures to above 100 °C (Tmax > 100 °C). Gel polymerization under these conditions produces anionic DPAM polymers for use in variety of industrial applications with improved standard viscosity and high water-solubility.

Inventors

  • HOLAPPA, Susanna

Assignees

  • KEMIRA OYJ

Dates

Publication Date
20260513
Application Date
20240703

Claims (15)

  1. 1. A method for preparing a high reaction temperature dry polyacrylamide (DPAM) by redox initiated free-radical polymerization, the method comprising: (a) providing an aqueous solution of ethylenically unsaturated monomers comprising water and (i) acrylamide or (ii) acrylamide and one or more additional monomers capable of copolymerizing with acrylamide; (b) optionally adding one or more stabilizers; (c) optionally adding one or more additives, including but not limited to, one or more chelators, and optionally, one or more chaotropic agents, one or more chain transfer agents, or any combination thereof; (d) adding one or more azo initiators; (e) adjusting the pH to a range of 7-9, 7-8, 7.1-7.8, or 7.25-7.75; (f) cooling to a redox initiation temperature of less than 25 °C; (g) adding one or more redox initiators, thereby producing a redox initiated reaction mixture; (h) allowing a gel polymerization to occur under essentially adiabatic conditions, wherein said redox initiated reaction mixture is heated by an exothermic heat of polymerization to a maximum reaction temperature (Tmax) of greater than 100° C; and (i) maintaining said Tmax for a curing time, thereby providing a high reaction temperature polyacrylamide gel.
  2. 2. The method of claim 1, further comprising after step (i), drying, and milling said high reaction temperature polyacrylamide gel to form said high reaction temperature DPAM as a homopolymer, copolymer, or terpolymer.
  3. 3. The method of claim 1 or 2, wherein said gel polymerization: (a) occurs under an atmosphere comprising nitrogen, argon, helium, or a combination thereof; and/or (b) occurs under a high pressure which is greater than atmospheric pressure and is maintained optionally by heating by said exothermic heat of polymerization or by pressurizing with an inert gas, including but not limited to, nitrogen, argon, helium, or any combination thereof, and further wherein said high pressure is sufficient to prevent boiling of the aqueous reaction mixture when subjected to temperatures greater than 100 °C.
  4. 4. The method of any one of claims 1, 2, or 3, wherein one, two, three or all four of the following are satisfied: (a) said redox initiation temperature ranges from -10 to 25 °C, -10 to 15 °C, -10 to 10 °C, -10 to 5 °C, or -6 to 3 °C; (b) said final reaction temperature ranges from 100 to 150 °C, 100 to 140 °C, 100 to 130 °C, 100 to 120 °C, 100 to 110 °C, or 100 to 105 °C; (c) after addition of said one or more redox initiators, said final reaction temperature is reached over a time ranging from 5-120 min, 10-90, 20-90, or 20-60 min; and (d) said curing time ranges from 10-240 min, 30-180 min, or 60-120 min.
  5. 5. The method of any one of the foregoing claims, wherein said one or more additional monomers comprises: (a) one or more ethylenically unsaturated, preferably water-soluble, nonionic monomers, including but not limited to, (meth)acrylamide; N-alkylacrylamides, including but not limited to, N-methylacrylamide, N-ethylacrylamide, N-propylacrylamide, and N- butylacrylamide; N,N-dialkylacrylamides, including, but not limited to, N,N- dimethylacrylamide and N,N-diethylacrylamide; N-alkyl methacrylamides; alkyl acrylates; hydroxyalkyl acrylates and methacrylates, including but not limited to, hydroxymethyl acrylate, 2-hydroxyethyl acrylate, 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, hydroxymethyl methacrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl methacrylate, and 4-hydroxybutyl methacrylate; dihydroxyalkyl acrylates and methacrylates, including but not limited to, 2,3-dihydroxypropyl acrylate, 3,4- dihydroxybutyl acrylate, 2,3-dihydroxypropyl methacrylate (DHPMA), and 3,4- dihydroxybutyl methacrylate; alkyl acrylates, including but not limited to, methyl methacrylate; acrylonitrile; N-vinylmethylacetamide, N-vinylmethylformamide; N-vinyl acetate, glyoxalated acrylamides, and vinyl pyrrolidone; (b) one or more ethylenically unsaturated anionic monomers, including but not limited to, acrylic acid, methacrylic acid; sulfonic acids, phosphonic acids, maleic acid, itaconic acid, vinyl sulfonic acid, acrylamido tertiary butyl sulfonic acid (ATBS), acrylamido methanesulfonic acid, acrylamido ethanesulfonic acid, 2-hydroxy-3-acrylamide propane sulfonic acid, styrene sulfonic acid, vinyl phosphonic acid, and alkali metal salts, alkaline earth metal salts, and ammonium salts thereof; or (c) any combination of the foregoing.
  6. 6. The method of any one of the foregoing claims, wherein said aqueous solution of ethylenically unsaturated monomers comprises: (a) acrylamide; (b) acrylamide and acrylic acid; or (c) acrylamide, acrylic acid, and ATBS.
  7. 7. The method of any one of the foregoing claims, wherein: (a) said one or more optional stabilizers comprise one or more radical scavengers, including but not limited to, thiourea, N,N'-dimethylthiourea, N,N'-diethylthiourea, N,N'- diphenylthiourea, thiocyanates, tetramethylthiuram disulfide, 2-mercaptobenzothiazole (MBT) and salts thereof, 2-mercaptobenzimidazole and salts thereof, sodium dimethyldithiocarbamate, sodium diethyldithiocarbamate 2,2'-dithiobis(benzothiazole ), 4,4'-thiobis( 6-t-butyl-m-cresol), dicyandiamide, cyanamide, paramethoxyphenol, 2,6-di- t-butyl-4-methylphenol, butylhydroxyanisole, 8-hydroxyquinoline, 2,5-d i(t- amyl)hydroquinone, 5-hydroxy-l,4-naphthoquinone, dimedone, propyl-3,4,5- trihydroxybenzoate, ammonium N-nitrosophenylhydroxylamine, 4-hydroxy-2,2,6,6- tetramethyoxylpiperidine, (N-(l,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, l,2,2,6,6-pentamethyl-4-piperidinol, or any combination of the foregoing; (b) said one or more additives comprise: (i) said one or more chelators, including but not limited to, diethylenetriaminepentaacetic acid, ethylenediaminetetraacetic acid (EDTA) and salts thereof, 2,2',2",2"'-(l,4,7,10-Tetraazacyclododecane-l,4,7,10-tetrayl)tetraacetic acid (DOTA), phosphoric acid, and alkali metal salts, alkaline earth metal salts, and ammonium salts thereof; (ii) said one or more chaotropic agents, including but not limited to, urea, thiourea, alcohols, glycerol, guanidine, and guanidinium halide salts; (iii) said one or more chain transfer agents, including but not limited to, hypophosphorous acid and salts thereof, sodium hypophosphite, sodium formate, pentamethyldisilane (PMDS), isopropyl alcohol, n-butyl mercaptan, chloroform, carbon tetrachloride, carbon tetrabromide, bromotrichloromethane, 4- methylbenzenethiol, and 4,4'-thiobisbenzenethiol; or (iv) any combination of the foregoing; (c) said one or more azo initiators are selected from the group consisting of azobisisobutyronitrile (AIBN), 2,2'-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride; 2,2-azobis(2-methylpropionamidine) dihydrochloride; 2,2'-azobis(A/-(2-carboxyethyl)-2- methylpropionamidine hydrate; 2,2'-azobis{ 2-[l-(2-hydroxyethyl)-2-imidazolin-2- yl]propene} dihydrochloride; and 2,2'-azobis(l-imino-l-pyrrolidino-2-ethylpropane) dihydrochloride; and (d) said one or more redox initiators are selected from the group of redox initiator systems consisting of ammonium persulfate and ammonium iron(ll) sulfate (APS/FAS); tert-butyl hydroperoxide and sodium sulfite (tBHP/SS); Fe(l I )/Fe(l 11 )-hydrogen peroxide systems, Fe( I l)/Fe( I II )-a Ikyl hydroperoxides systems, alkyl hydroperoxides-sulfite systems, peroxides-thiosulfate systems, alkyl hydroperoxides-sulfinates systems; alkyl hydroperoxides-hydroxymethanesulfinate systems, and t-butyl hydroperoxide-sodium hydroxymethanesulfinate systems; or (e) any combination of the foregoing.
  8. 8. The method of any one of the foregoing claims, wherein: (a) said one or more optional stabilizers comprise sodium 2-mercaptobenzothiazole (Na-2- MBT); (b) said one or more azo initiators comprise AIBN; and (c) said one or more redox initiators comprise ammonium persulfate and ammonium iron(ll) sulfate (APS/FAS) or tert-butyl hydroperoxide and sodium sulfite (tBHP/SS).
  9. 9. The method of any one of the foregoing claims, wherein said one or more additives comprise: (a) diethylenetriaminepentaacetic acid; (b) diethylenetriaminepentaacetic acid and urea; (c) diethylenetriaminepentaacetic acid and sodium hypophosphite; or (d) diethylenetriaminepentaacetic acid, sodium hypophosphite, and urea.
  10. 10. The method of any one of the foregoing claims, wherein said redox initiated reaction mixture comprises: (a) a total monomer concentration ranging from 30-60%, 32-55%, 32-50%, or 36-42% by wt based on all components therein, wherein said total monomer concentration is sufficient to heat said redox initiated reaction mixture from said redox initiation temperature to said Tmax of greater than 100° C, wherein said redox initiated reaction mixture is heated by said exothermic heat of polymerization; (b) a mole percent of acrylamide in said total monomer concentration ranging from 1-100%, 35-95%, or 65-85%; (c) a mole percent of said one or more additional monomers in said total monomer concentration ranging from 0-99%, 5-65%, or 15-35%; (d) optionally a stabilizer concentration ranging from 0.01-2%, 0.02-1.5%, or 0.05-1.0% by wt based on total weight of monomers therein; and (e) an equilibrium redox initiator product concentration (e.g., oxidant x reductant) ranging from 50-6000, 100-5000, 200-5000, 500-5000, 1000-5000, or 1000-3000 [(pmol/kg) 2 ].
  11. 11. The method of any one of the foregoing claims, wherein: (a) the pH ranges from 7.2-7.8, the equilibrium redox initiator product concentration of tBHP/SS ranges from 750-5000 [(pmol/kg) 2 ], the redox initiation temperature ranges from -4 to 6 °C, -4 to 2 °C, or -4 to -2 °C, and the total monomer concentration ranges from 36-42% by wt; or (b) the pH ranges from 7.2-7.8, the equilibrium redox initiator product concentration of APS/FAS ranges from 50-400 [(pmol/kg) 2 ], and the redox initiation temperature ranges from -4 to 6 °C, -4 to 2 °C, or -4 to -2 °C, and the total monomer concentration ranges from 36-42% by wt.
  12. 12. The method of any one of the foregoing claims, wherein said high reaction temperature DPAM: (a) has a standard viscosity (SV) ranging from 6.0-7.5 mPas, 6.5-7.4 mPas, or 7.0-7.2 mPas, determined using a Brookfield viscometer DV1MLV with a UL adapter and a ULA-DIN-Y spindle at 25 °C ± 0.2 °C and 60 rpm; (b) has a high water solubility as determined by residual insoluble gel content ranging from 0-0.5% by wt, 0-0.2% by wt, 0-0.1% by wt, or 0-<0.1% by wt, determined by dissolving 1 g of said high reaction temperature DPAM in 1 L of water at 25 °C and then filtering through a 300 pm aperture; (c) has a higher standard viscosity (SV) and higher water solubility compared to a DPAM polymer prepared using the same monomers and same high temperature (Tmax > 100 °C) method with the exceptions of lower pH; or (d) any combination of the foregoing.
  13. 13. A method for preparing a high reaction temperature dry polyacrylamide (DPAM) by redox initiated free-radical polymerization according to claim 1, the method comprising: (a) providing an aqueous solution of ethylenically unsaturated monomers comprising water and (i) acrylamide or (ii) acrylamide and one or more additional monomers selected from the group consisting of acrylic acid and salts thereof, acrylamido tertiary butyl sulfonic acid (ATBS) and salts thereof, or a combination of acrylic acid and sodium ATBS; (b) adding 2-mercaptobenzothiazole (MBT) or salts thereof; (c) adding diethylenetriaminepentaacetic acid; (d) adding azobisisobutyronitrile (AIBN); (e) adjusting the pH to a range of 7-8, 7.1-7.8, or 7.25-7.75; (f) cooling to a redox initiation temperature ranging from less than 25 °C, -10 to 25 °C, -10 to 15 °C, -10 to 10 °C, -10 to 5 °C, or -6 to 3 °C; (g) adding one or more redox initiators selected from the group of redox initiator systems consisting of ammonium persulfate and ammonium iron(ll) sulfate (APS/FAS) system; tert-butyl hydroperoxide and sodium sulfite (tBHP/SS) system, thereby producing a redox initiated reaction mixture; (h) allowing a gel polymerization to occur under essentially adiabatic conditions and under a high pressure inert gas atmosphere, wherein said high pressure is sufficient to prevent boiling, wherein said redox initiated reaction mixture is heated by an exothermic heat of polymerization to a maximum reaction temperature (Tmax) ranging from greater than 100 °C, 100 to 150 °C, 100 to 140 °C, 100 to 130 °C, 100 to 120 °C, or 100 to 110 °C, wherein said gel polymerization occurs; (i) maintaining said Tmax for a curing time ranging from 10-240 min, 30-180 min, or 60-120 min, thereby providing a high reaction temperature polyacrylamide gel; and (j) optionally drying and milling said high reaction temperature polyacrylamide gel to form said high reaction temperature DPAM; wherein the resultant high reaction temperature DPAM is a homopolymer, copolymer, or terpolymer.
  14. 14. The method of claim 13, wherein said redox initiated reaction mixture comprises one or more of: (a) a total monomer concentration ranging from 32-50%, or 36-42% by wt based on all components therein; (b) a mole percent of acrylamide in said total monomer concentration ranging from 1-100%, 35-95%, or 65-85%; (c) a mole percent of said one or more additional monomers in said total monomer concentration ranging from 0-99%, 5-65%, or 15-35%; (d) a stabilizer concentration ranging from 0.01-2%, 0.02-1.5%, or 0.05-1.0% by wt based on total weight of monomers therein; (e) an equilibrium redox initiator product concentration (e.g., oxidant x reductant) of tBHP/SS ranging from 750-5000, 1000-5000, or 1000-3000 [(pmol/kg) 2 ] or an equilibrium redox initiator product concentration (e.g., oxidant x reductant) of APS/FAS ranging from 50-1000, 50-600, or 50-400 [(pmol/kg) 2 ]; or (f) any combination of the foregoing.
  15. 15. A composition comprising a high reaction temperature dry polyacrylamide (DPAM), obtainable or produced by a method according to any of the foregoing claims.

Description

PREPARATION OF A HIGH REACTION TEMPERATURE DPAM HAVING IMPROVED STANDARD VISCOSITY AND WATER SOLUBILITY FIELD OF THE INVENTION [0001] The present application claims benefit of priority to US Provisional Application No.: 63/511,978, filed on July 5, 2023, and to Finnish Application Number 20236044 filed on September 21, 2023, the contents of both of which are incorporated by reference in their entireties. FIELD OF THE INVENTION [0002] The present invention generally relates to compositions and methods for preparation of high reaction temperature dry polyacrylamide (DPAM) polymers. In particular, the disclosure provides methods for adiabatic redox initiated free-radical polymerization of reaction mixtures comprising at least acrylamide monomers, optional free-radical scavenger stabilizers, azo initiators, and redox initiators under pH and initial temperature conditions that allow heat of polymerization to increase reaction temperatures to above 100 °C (Tmax > 100 °C). Gel polymerization under these conditions produces anionic DPAM polymers for use in variety of industrial applications with improved standard viscosity and high water-solubility BACKGROUND OF THE INVENTION [0003] Polyacrylamide homopolymers and copolymers having high molecular weight, high watersolubility, and high standard viscosity in solution are used in many fields of industry, for example as thickeners, flocculants, strengtheners for paper, for enhanced oil recovery, for tailings treatment, wastewater treatment, drinking water treatment, and for mining applications. [0004] Such polymers, especially high molecular weight polyacrylamides, are of critical importance for enhanced oil recovery (EOR). EOR techniques, such as polymer flooding wherein large volumes of a polymer solution are injected into a subterranean oil reservoir, can be used to increase the amount of unrefined petroleum (e.g., crude oil) that may be extracted from an oil reservoir (e.g., an oil field). By way of example, using EOR, about 40-60% of the reservoir's original oil can typically be extracted, compared with only 20-40% using traditional primary and secondary recovery techniques (e.g., by water injection or natural gas injection). [0005] One of the largest uses for polyacrylamide is to flocculate solids in a liquid for the purpose of dewatering and filtering. Many industrial processes use dewatering and filtering steps, in which the water content of a bulk solid or slurry is reduced by filtering or other methods. Dewatering processes are necessary, for example, in the treatment of sludge (for example, in sludge ponds or sludge from municipal wastewater treatment process), slurries and in paper-based pulp as well as in other paper treatment processes. Dewatering methods are also used in mining, for example, in dewatering of mine tailings, and metal ores. Specifically, the mining, processing, and purification of naturally occurring minerals often involve one or more processing or treatment operations in which fine mesh size particles of the mineral of interest are suspended or dispersed in a continuous medium, e.g., a continuous aqueous medium, and the mineral particles are then separated from the medium. [0006] Flocculants that comprise polyacrylamide homopolymers and copolymers having high molecular weight are commonly used as a chemical treatment for dewatering oil sands tailings, sludge, and other wastewater. Polyacrylamide flocculants are widely employed in the purification of drinking water as well as in sewage treatment, storm-water treatment, treatment of industrial wastewater streams, and to facilitate settling in slurries comprising mined mineral and ore. [0007] Polyacrylamides and copolymers thereof are also used extensively in pulp and paper applications. Polyacrylamide homopolymers and copolymers are used as retention aids (if molecular mass > 2 million g/mole), dry-strength resins, pitch-control agents, and micro-polymer drainage aids. [0008] Preparation of homopolymers and copolymers of acrylamide having high molecular weight, high water-solubility, and high standard viscosity in solution is essential for the aforementioned industrial applications. Such polymers are typically prepared as dry polyacrylamides (DPAMs) using gel polymerization methods, such as adiabatic redox initiated free-radical gel polymerization. [0009] Considerable effort has been directed toward gel polymerization methods for preparing high reaction temperature DPAMs (i.e., produced at high temperatures (Tmax) exceeding 100 °C) with high molecular weight, good solubility (low residual insoluble gel) and high viscosity (SV 6-7.5 mPas). Use of high monomer concentration is beneficial for achieving optimal molecular weight and high viscosity. However, such efforts have been unsuccessful due to unwanted side reactions at Tmax greater than 100 °C and possible ultra-high molecular weight polymer strand formation during polymerization at high monomer concentration. Such phenomena cause undes