Crystal form of 2-acrylamido-2-methylpropanesulfonic acid potassium salt

Abstract

The invention relates to a crystal form of 2-acrylamide-2-methylpropanesulfonic acid potassium salt (ATBS.K). The X-ray powder diffraction pattern of the crystal form has characteristic peaks at 2 theta (+ / -0.1 degrees) of 13.1 degrees, 14.4 degrees, 16.3 degrees, 19.8 degrees, 23.5 degrees, 24.3 degrees, 26.9 degrees, 27.6 degrees, 29.3 degrees, 30.6 degrees, 31.6 degrees, 34.3 degrees, 36.1 degrees, 41.7 degrees, 44.6 degrees and 46.7 degrees.

Description

TECHNICAL FIELD

[0001] The present invention relates to a crystalline form of 2-acrylamido-2-methylpropane sulfonic acid. More specifically, the present invention relates to a crystalline form of the potassium salt of 2-acrylamido-2-methylpropane sulfonic acid. The present invention also relates to a process for preparing the crystalline form of the potassium salt of 2-acrylamido-2-methylpropane sulfonic acid and to a polymer made from the crystalline form. BACKGROUND

[0002] 2-Acrylamido-2-methylpropane sulfonic acid, also known as ATBS, is widely used in the acrylic fiber industry as an additive or as a raw material for producing polymers. The polymers can be used as dispersants, thickeners, friction reducers, flocculants or superabsorbent materials in the oil and gas industry, mining, construction, textile, water treatment (desalination, mineral processing, etc.) and cosmetic industries.

[0003] In the process for preparing 2-acrylamido-2-methylpropane sulfonic acid, the reaction is carried out following the reaction scheme: an excess of acrylonitrile is used both as a reaction solvent and as a reactant, and acrylonitrile is contacted with oleum and isobutylene.

[0004] [Reaction 1]

[0005]

[0006] One of the by-products that can be produced in this synthesis is acrylamide.

[0007] 2-Acrylamido-2-methylpropane sulfonic acid is not soluble in the acrylonitrile solvent, so the reaction product is present in the reaction solvent in the form of a suspension of crystals.

[0008] For example, US 6,448,347 and CN 102351744 describe a process for the continuous production of 2-acrylamido-2-methylpropane sulfonic acid. The process generally involves separating 2-acrylamido-2-methylpropane sulfonic acid from acrylonitrile by filtration, followed by a drying process.

[0009] It is necessary to dry 2-acrylamido-2-methylpropane sulfonic acid to reduce the content of acrylonitrile and acrylamide remaining in the crystals. Both of these compounds are classified as carcinogenic, mutagenic or reprotoxic substances (CMR). Therefore, it is necessary to perform an effective filtration to remove acrylonitrile as completely as possible, and then dry the 2-acrylamido-2-methylpropane sulfonic acid to obtain a low content of acrylonitrile and acrylamide.

[0010] As is known by those skilled in the art, the lattice arrangement of the 2-acrylamido-2-methylpropane sulfonic acid crystals forms needle-shaped solid crystals.

[0011] As known to the person skilled in the art, the macroscopic properties of acicular crystals cause difficulties in the handling and transport operations of solid materials (poor flowability, tendency to form lumps, low resistance to shear stress) and in the process operations (poor filtration, difficulty in drying, tendency to attrition).

[0012] For 2-acrylamido-2-methylpropane sulfonic acid, the additional problems typically encountered include the small size of the acicular crystals, the density properties of the solid material and the explosiveness of the fine dust.

[0013] These macroscopic properties are directly related to the crystal form and to its specific surface area. Acicular crystals have the property of having a high specific surface area.

[0014] Patents WO 2009 / 072480, JP 2008 / 307822 and JP 2003 / 137857 all indicate that the 2-acrylamido-2-methylpropane sulfonic acid crystals obtained are acicular.

[0015] The application WO 2018 / 172676 filed by the Applicant describes a new crystal form, called "2-acrylamido-2-methylpropane sulfonic acid hydrated crystal form". This new crystal form has physicochemical properties different from the acicular crystals and enables polymers of 2-acrylamido-2-methylpropane sulfonic acid containing this new crystal form to have more excellent properties.

[0016] However, regardless of the form in which 2-acrylamido-2-methylpropane sulfonic acid is present, due to the strong acidity of its sulfonic group, this substance is always a strong acid with a high degree of corrosion of metals. In view of the fine particle properties of the 2-acrylamido-2-methylpropane sulfonic acid powder, there is also the risk of chemical burns due to the contact of the fine particles suspended in the air with the skin or the eyes, or their inhalation into the lungs, during the powder handling operations.

[0017] When 2-acrylamido-2-methylpropane sulfonic acid is used in polymerization reactions, it must be converted into an aqueous solution form. This aqueous phase can be used directly in the acidic form or after neutralization with alkali metals, alkaline earth metals or molecules containing unsubstituted / substituted amine groups.

[0018] The shelf life of this aqueous solution is generally short, due to the phenomenon of self-polymerization induced by temperature, UV light or contaminants such as iron and its oxidized forms. These contaminants can originate from the corrosion of the metal pipes or containers by the acidic form of 2-acrylamido-2-methylpropane sulfonic acid. In addition, the temperature increase resulting from the self-polymerization of 2-acrylamido-2-methylpropane sulfonic acid far exceeds the boiling point of water, which can cause an increase in the pressure inside the container and trigger an explosion. Therefore, the phenomenon of self-polymerization poses a risk to the safety of personnel and to the equipment.

[0019] Applicants have discovered a new form of 2-acrylamido-2-methylpropane sulfonic acid, called "2-acrylamido-2-methylpropane sulfonic acid potassium salt crystalline form" (hereinafter ATBS.K). This new form provides superior physico-chemical and application properties (similar to the "hydrated crystal" form) while avoiding the neutralization stage, and reducing the risks of burns, corrosion and self-polymerization. Finally, the ATBS.K crystalline form has a longer shelf life than its aqueous solution.

[0020] The use of the ATBS.K crystalline form according to the present application is in line with the principles of environmental awareness and helps to reduce the impact of industrial and human activities on the planet. The new form of the product makes it safer to use for the operators, while reducing the energy consumption impact - both because the neutralization step is no longer necessary in the ATBS polymerization process, and because the powder form allows for a higher active ingredient transport (100% active ingredient content in the powder form, versus a maximum of 50% in the solution form). The extension of the shelf life of the product means that the waste resulting from the need to increase the dosage due to the degradation of the product properties is reduced. In addition, the improvement in the properties of the polymer made from the ATBS.K crystalline form according to the present application helps to reduce the total amount of product needed in its field of application, thus reducing the overall water consumption and the emission of greenhouse gases such as carbon dioxide.

[0021] The present application discloses

[0022] The present application aims to provide a specific form of 2-acrylamido-2-methylpropane sulfonic acid, hereinafter called "2-acrylamido-2-methylpropane sulfonic acid potassium salt crystalline form".

[0023] The present application also relates to a process for producing the ATBS.K crystalline form.

[0024] The present application further relates to the use of the ATBS.K crystalline form for the preparation of water-soluble, water-swellable or superabsorbent polymers.

[0025] The present application also relates to a process for treating a suspension of solid particles in water, comprising contacting said suspension with at least one water-soluble polymer, which is at least partially made from the ATBS.K crystalline form, and which has an X-ray powder diffraction pattern having characteristic peaks at 13.1°; 14.4°; 16.3°; 19.8°; 23.5°; 24.3°; 26.9°; 27.6°; 29.3°; 30.6°; 31.6°; 34.3°; 36.1°; 41.7°; 44.6°; 46.7° 2Q (± 0.1°).

[0026] The present application also relates to a method for improving the recovery of hydrocarbons (oil and / or gas) comprising the steps of:

[0027] The present application also relates to a method for improving the recovery of hydrocarbons (oil and / or gas) comprising the steps of:

[0028] a) preparing an injection fluid comprising at least one 2-acrylamido-2-methylpropane sulfonic acid water-soluble polymer and water or brine;

[0029] said 2-acrylamido-2-methylpropane sulfonic acid being at least partially in the ATBS.K crystalline form before polymerization and said ATBS.K crystalline form having a X-ray powder diffraction pattern with characteristic peaks at 13.1°; 14.4°; 16.3°; 19.8°; 23.5°; 24.3°; 26.9°; 27.6°; 29.3°; 30.6°; 31.6°; 34.3°; 36.1°; 41.7°; 44.6°; 46.7° 2Q (± 0.1°);

[0030] b) injecting the injection fluid into a subterranean formation;

[0031] c) displacing the subterranean formation with the injection fluid;

[0032] d) producing a water-containing hydrocarbon mixture (a mixture comprising water and hydrocarbons).

[0033] The present application also relates to a fracturing fluid comprising at least one proppant and at least one water-soluble polymer, said polymer being at least partially made from the ATBS.K crystalline form and said ATBS.K crystalline form having a X-ray powder diffraction pattern with characteristic peaks at 13.1°; 14.4°; 16.3°; 19.8°; 23.5°; 24.3°; 26.9°; 27.6°; 29.3°; 30.6°; 31.6°; 34.3°; 36.1°; 41.7°; 44.6°; 46.7° 2Q (± 0.1°).

[0034] The present application also relates to a method for producing a fracturing fluid comprising at least one water-soluble polymer, said polymer being at least partially made from the ATBS.K crystal form, and said ATBS.K crystal form having an X-ray powder diffraction pattern with characteristic peaks at 13.1°; 14.4°; 16.3°; 19.8°; 23.5°; 24.3°; 26.9°; 27.6°; 29.3°; 30.6°; 31.6°; 34.3°; 36.1°; 41.7°; 44.6°; 46.7° 2Q (± 0.1°).

[0035] The present application also relates to a method for hydraulic fracturing of unconventional subterranean reservoirs using the fracturing fluid according to the present application.

[0036] The present application also relates to a method for achieving a reduction of the resistance in hydraulic fracturing operations of unconventional subterranean reservoirs using the fracturing fluid according to the present application.

[0037] The present application also relates to the use of a polymer made at least partially from the ATBS.K crystal form in the following fields: drilling or cementing operations; profile control, flow diversion; open, closed or semi-closed circuit water treatment; fermentation broth treatment; sludge treatment; construction work; paper or paperboard manufacturing; batteries; wood treatment; water-hardening compositions (concrete, cement, mortar and aggregates) treatment; cosmetic formulations; detergent formulations; textile manufacturing; geothermal energy; diaper manufacturing; or the agricultural field.

[0038] Finally, the present application also relates to the use of a polymer made at least partially from the ATBS.K crystal form as a coagulant, a binder, a viscosity reducer, a thickener, an absorbent, a drainage agent, a filler retention agent, a dehydrating agent, a conditioning agent, a stabilizing agent, a fixing agent, a film-forming agent, a sizing agent, a superplasticizing agent, a clay inhibitor or a dispersing agent. SUMMARY

[0039] The term "polymer" is understood as a homopolymer or a copolymer. The term "copolymer" is understood as a polymer made from at least two different monomers. It can thus be a copolymer of at least two monomers chosen from the group consisting of hydrophilic anionic monomers, hydrophilic cationic monomers, hydrophilic non-ionic monomers, hydrophilic zwitterionic monomers, hydrophobic monomers and mixtures thereof.

[0040] The term "hydrophilic monomer" is understood as a monomer having an octanol-water partition coefficient (K ow ) equal to or less than 1, measured at 25°C in a 1 / 1 volume mixture of octanol-water at a pH value of between 6 and 8. ow

[0041] ​The term "crystal" or "crystalline form" refers to a solid material whose constituent units, such as atoms, molecules, or ions, are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. The term does not include amorphous solids.

[0042] The term "hydrophobic monomer" is understood to mean a monomer having an octanol-water partition coefficient (K ow ) greater than 1, wherein the partition coefficient K ow is determined at 25°C in a 1 / 1 volume mixture of octanol-water at a pH of between 6 and 8.

[0043] The octanol-water partition coefficient (K ow ) represents the ratio of the concentrations (g / L) of the monomer in the octanol phase and in the water phase, and is defined as follows:

[0044] [mathematical formula 1]

[0045]

[0046] By definition, a water-soluble polymer is a polymer that forms an aqueous solution when stirred and dissolved in water at a concentration of 10 g / L at 25°C.

[0047] "X and / or Y" is understood to mean "X", "Y" or "X and Y".

[0048] The present disclosure also includes all possible combinations of the disclosed embodiments, whether these embodiments are preferred or exemplary. Furthermore, when numerical ranges are indicated, the limits of these ranges are included in the range. The present disclosure also includes all combinations of the limits of these numerical ranges. For example, the numerical range "1-20, preferably 5-15" means that the ranges "1-5", "1-15", "5-20" and "15-20" as well as the numbers 1, 5, 15 and 20 are disclosed.

[0049] Crystalline form of ATBS.K

[0050] The present invention relates to a crystalline form of potassium 2-acrylamido-2-methylpropane sulfonate (hereinafter ATBS.K) having an X-ray powder diffraction pattern showing characteristic diffraction peaks at 13.1°, 14.4°, 16.3°, 19.8°, 23.5°, 24.3°, 26.9°, 27.6°, 29.3°, 30.6°, 31.6°, 34.3°, 36.1°, 41.7°, 44.6° and 46.7° 2Θ. The measurement uncertainty of these peaks is typically ±0.1°.

[0051] X-ray crystallography (also known as X-ray diffraction analysis or X-ray diffraction analysis) is an analytical technique for studying the structure of crystalline materials at the atomic scale, based on the physical phenomenon of X-ray diffraction. The experiment can be performed using a diffractometer equipped with a copper source.

[0052] A powder composed of a specific crystalline phase will always show diffraction peaks in the same direction, and the diffraction pattern thus constitutes a unique identification feature of the crystalline phase. By this technique it is possible to accurately determine the specific composition of each crystalline phase in a mixture or in a pure substance.

[0053] This characteristic spectrum is specific for each organic or inorganic compound and is represented as a list of diffraction peaks at a series of 2-theta angles.

[0054] This technique is used for substance characterization, in particular for the identification of different crystalline forms (also called polymorphs) of the same chemical molecule.

[0055] Another aspect of the present invention relates to an ATBS.K crystalline form having a Fourier transform infrared spectrum showing characteristic absorption peaks at 3293 cm -1 , 3075 cm -1 , 3000 cm -1 , 2979 cm -1 , 1655 cm -1 , 1625 cm -1 , 1550 cm -1 , 1405 cm -1 , 1209 cm -1 , 1190 cm -1 , 1162 cm -1 , 1048 cm -1 , 979 cm -1 , 824 cm -1 , 803 cm -1 , 756 cm -1 , 633 cm -1 , and 523 cm -1 . The measurement uncertainty of these peaks is typically ± 8 cm -1 .

[0056] The infrared measurements are performed by Fourier transform, for example using a Perkin Elmer Spectrum 100 spectrometer equipped with a single reflection ATR polarized accessory, with a measurement accuracy of 8 cm -1 .

[0057] The Fourier transform infrared spectroscopy technique mainly analyzes the vibrational signals emitted, absorbed or scattered by a molecule. This technique is very sensitive to so-called short-range interactions (influence of the chemical bond on the unit cell). In most cases, the Fourier transform infrared spectra of different crystalline systems differ significantly. Thus, the Fourier transform infrared spectrum reflects the detailed characteristics of the crystal structure of a compound.

[0058] X-ray diffraction patterns and infrared spectra are generally obtained at a temperature of 20°C and at 1 standard atmosphere (101,325 Pa) unless otherwise stated.

[0059] Another aspect of the application relates to an ATBS.K crystalline form having a minimum ignition energy greater than 500 mJ, preferably greater than 1000 mJ.

[0060] Minimum ignition energy refers to the lowest energy input, which can be electrical or thermal, required to ignite a product (compound). The minimum ignition energy is a crucial parameter when assessing the risk of explosion in the handling of a product (transfer, storage, reaction, shaping, etc.).

[0061] The minimum ignition energy depends on the characteristics (composition) of the powder and its macroscopic molecular structure (particle size, crystalline form, specific surface area).

[0062] For a solid substance, this energy refers to the minimum energy of an electric spark that can ignite a dust cloud. The higher the minimum ignition energy value, the lower the risk of the solid during use, handling or storage.

[0063] The minimum ignition energy is determined according to the NF EN 13821 standard.

[0064] Another aspect of the application relates to an ATBS.K crystalline form having two thermal phenomena detected by differential scanning calorimetry at 79.4°C and 207°C. The observed uncertainty of these thermal phenomena is generally 10°C (± 10°C), preferably 5°C or less.

[0065] The thermal phenomena are measured by differential scanning calorimetry (DSC). This technique makes it possible to measure the heat change associated with thermal denaturation of a compound during constant rate heating, for example at a temperature rise rate of 10°C / min.

[0066] Process for the preparation of the ATBS.K crystalline form

[0067] The application also relates to a process for the preparation of the ATBS.K crystalline form, comprising at least the following successive steps:

[0068] 1 ) mixing 2-acrylamido-2-methylpropanesulfonic acid with an aqueous solution SAl and at least one potassium salt base, preferably for at least 1 minute, to form an aqueous solution or an aqueous suspension SA2;

[0069] 2) subjecting the aqueous solution or the aqueous suspension SA2 to distillation at a pressure of 700 mbar or less, to form a suspension S1 ;

[0070] 3) subjecting the suspension S1 to a solid-liquid separation, separating the crystals in the suspension S1 obtained at the end of step 2), to obtain a composition C1.

[0071] The obtained crystals are in the ATBS.K crystal form.

[0072] In step 1), the "potassium salt base" is understood to be at least one inorganic potassium salt Brønsted base (base), such as potassium hydroxide, potassium carbonate, potassium bicarbonate or a mixture thereof. base), such as potassium hydroxide, potassium carbonate, potassium bicarbonate or a mixture thereof.

[0073] The temperature and mixing time of step 1) can be adjusted in particular as a function of the concentration of 2-acrylamido-2-methylpropanesulfonic acid (ATBS). The person skilled in the art knows how to optimize the formation of crystals by adjusting the temperature variation and the mixing time.

[0074] The method for preparing the ATBS.K crystal form can be applied to any form of ATBS raw material, such as a needle-shaped crystal form or a hydrated crystal form.

[0075] This production method can be applied to any purity grade of ATBS raw material.

[0076] Thus, the method can be implemented downstream of any type of ATBS production process, but also for reprocessing already obtained ATBS crystals.

[0077] Step 1) of the method for preparing the ATBS.K crystal form:

[0078] ATBS is prepared by the aforementioned production method (acrylonitrile, fuming sulfuric acid and isobutene). 2-Acrylamido-2-methylpropanesulfonic acid can be in the form of a fine powder or can be controllably shaped by processes such as compaction, granulation or extrusion.

[0079] ATBS can be added to the aqueous solution SA1 before, after or simultaneously with the addition of the potassium salt base, preferably simultaneously. The aqueous solution SA1 is preferably water.

[0080] The potassium salt base can be added in the form of an aqueous solution. In this case, the potassium salt base aqueous solution can be used partially or totally as the aqueous solution SA1.

[0081] Preferably, the concentration of ATBS potassium salt in the aqueous solution or aqueous suspension SA2 ranges from 1% to the saturation concentration (percentage by weight, based on the total weight of SA2), more preferentially from 10% to the saturation concentration, further preferentially from 20% to the saturation concentration, more further preferentially from 30% to the saturation concentration, particularly preferentially from 40% to the saturation concentration, most preferentially from 50% to the saturation concentration.

[0082] ATBS and the potassium salt base can be added all at once or in stages. Preferentially, they are added in stages, but also preferentially all at once.

[0083] When added in stages, ATBS and the potassium salt base are added in portions.

[0084] There is no limit to the number of batches when the addition is carried out in stages, it being preferred for the addition to be carried out in at least two batches, more preferably in at least three batches.

[0085] The order of addition of ATBS and potassium salt base is not limited. The addition can be simultaneous (i.e. parallel addition), sequential (ATBS is added first and then the potassium salt base, or vice versa), or alternating (a first batch of ATBS is added, then a first batch of potassium salt base, then a second batch of ATBS and a second batch of potassium salt base, and so on); it being preferred for the addition to be simultaneous.

[0086] When sequential or alternating addition is used, the second compound (whether ATBS or potassium salt base) can be added while the first compound is not yet completely added.

[0087] The first batch F1 of ATBS preferably represents at least 1 %, more preferably at least 5 %, further preferably at least 10 %, particularly preferably at least 15 %, most preferably at least 20 % of the total amount of ATBS in the aqueous solution or aqueous suspension SA2.

[0088] The second batch F2 of ATBS preferably represents at least 1 %, more preferably at least 5 %, further preferably at least 10 %, particularly preferably at least 15 %, most preferably at least 20 % of the total amount of ATBS in the aqueous solution or aqueous suspension SA2.

[0089] The third batch F3 of ATBS preferably represents at least 1 %, more preferably at least 5 %, further preferably at least 10 %, particularly preferably at least 15 %, most preferably at least 20 % of the total amount of ATBS in the aqueous solution or aqueous suspension SA2.

[0090] In particular embodiments, the process is carried out in a continuous manner, in which case ATBS and potassium salt base are added in a continuous feed manner.

[0091] The content of ATBS in the aqueous solution or aqueous suspension SA2 is preferably between 10 and 90 % by weight, more preferably between 20 and 85 %, further preferably between 30 and 80 %, relative to the total weight of SA2.

[0092] The mixing process (ATBS + potassium salt base) of step 1) is preferably carried out at a temperature ranging from 0 to 90 °C, more preferably from 5 to 60 °C, further preferably from 10 to 40 °C, in order to obtain the aqueous solution or aqueous suspension SA2.

[0093] In particular embodiments, the aqueous solution or suspension SA2 can comprise one or more organic solvents.

[0094] In certain embodiments, the aqueous solution SA1 can also comprise one or more organic solvents.

[0095] The amount of organic solvent can be adjusted depending on the temperature and the amount of ATBS or potassium salt base. The amount is not limited as long as it does not affect the obtaining of the ATBS.K crystal form. The person skilled in the art can determine the amount limit by routine experiments. Generally, the volume fraction of water in the aqueous solution or aqueous suspension SA2 is higher than that of the organic solvent.

[0096] The organic solvent is preferably selected from the following compounds:

[0097] An organic acid, preferably a carboxylic acid comprising 1 to 8 carbon atoms;

[0098] An amide, preferably comprising 1 to 8 carbon atoms;

[0099] An alcohol, preferably comprising 1 to 8 carbon atoms;

[0100] A ketone, preferably comprising 3 to 8 carbon atoms;

[0101] An ether, preferably comprising 2 to 8 carbon atoms;

[0102] An ester, preferably comprising 2 to 8 carbon atoms;

[0103] An alkane, preferably comprising 4 to 8 carbon atoms, more preferably 5 to 6 carbon atoms;

[0104] A halogenated hydrocarbon compound, preferably comprising 1 to 8 carbon atoms;

[0105] A nitrile, preferably comprising 1 to 8 carbon atoms;

[0106] or a mixture of the above.

[0107] When the organic solvent is used in the present application, the temperature can be adjusted so that the mixture of the solvent and water remains liquid.

[0108] These compounds can be linear or branched, saturated or containing unsaturated bonds (unsaturated bonds correspond to double or triple bonds, such as C=C or C≡C).

[0109] The organic solvent is preferably selected from acetonitrile, isopropyl alcohol, acetic acid or a mixture thereof, more preferably acetonitrile.

[0110] The organic solvent is generally liquid at the temperature at which steps 2) and 3) are carried out, and is preferably partially miscible with water, more preferably completely miscible.

[0111] The organic solvent can be used, if necessary, to dissolve various impurities or by-products that coexist with ATBS (for the formation of the aqueous solution or aqueous suspension SA2). It is noted, however, that ATBS itself is not necessarily soluble in this solvent.

[0112] In a preferred embodiment of the present application, the aqueous solution or aqueous suspension SA2 does not contain an organic solvent.

[0113] In a preferred embodiment of the present application, the aqueous solution SA1 does not contain an organic solvent.

[0114] The mixing time of the aqueous solution SA1 with ATBS is preferably at least 1 minute, more preferably 1 to 600 minutes, further preferably 5 to 400 minutes, particularly preferably 10 to 240 minutes.

[0115] The compounds of step 1) can be mixed using a variety of techniques, including but not limited to: reactors with stirrers, loop reactors, static mixers, microreactors, plug flow reactors, stirred filter dryers (such as Nutsche filters), paddle mixers, double cone mixers, ploughshare mixers and disc mixers.

[0116] The pH value in step 1) is preferably controlled between 6 and 14, more preferably between 8 and 14, further preferably between 10 and 14, particularly preferably between 12 and 14, most preferably between 13 and 14.

[0117] The content of ATBS.K in the aqueous solution SA2 or in the aqueous suspension SA2 is preferably between 10 and 90% by weight, more preferably between 20 and 90%, further preferably between 30 and 90%, particularly preferably between 50 and 90%, also preferably between 20 and 85%, most preferably between 30 and 80% of the total weight of the solution or suspension.

[0118] Step 2) of the process for preparing the ATBS.K crystal form:

[0119] The distillation of the aqueous solution or aqueous suspension SA2 is carried out at a pressure of 700 mbar or less. This process is usually carried out in a vacuum distillation apparatus, typically an evaporator, and is therefore also referred to herein as "vacuum distillation".

[0120] When the aqueous solution or aqueous suspension SA2 is distilled through an evaporator or the like, the ATBS.K crystals begin to form. At this point, the ATBS, the at least one potassium salt base and the ATBS.K crystal solid particles coexist in the aqueous solution or aqueous suspension SA2.

[0121] The aqueous solution or aqueous suspension SA2 can be distilled using an evaporator, which can be a falling film evaporator, a rising film evaporator, a wiped film evaporator, a short path evaporator, a forced circulation evaporator, a spiral tube evaporator or a flash evaporator. A continuously stirred reactor can also be used. Preferably, the distillation is carried out in a wiped film evaporator, a short path evaporator or a forced circulation evaporator, more preferably a wiped film evaporator is used.

[0122] An evaporator is typically a device comprising an inlet for the solution to be treated (aqueous solution or aqueous suspension SA2), a discharge outlet for the distilled solvent (water and any organic solvent) and a discharge outlet for the suspension S1.

[0123] The residence time of the aqueous solution or aqueous suspension SA2 in the distillation apparatus, i.e. the distillation time at a pressure of 700 mbar or less, is preferably between 1 and 600 seconds, more preferably between 3 and 300 seconds, further preferably between 30 and 100 seconds. The residence time corresponds to the time required to complete step 2), i.e. the time required to produce the suspension S1 by distilling the aqueous solution or aqueous suspension SA2. In other words, when an evaporator is used, this time is the residence time of the ATBS (and / or the potassium salt crystal form thereof) between the inlet and the outlet of the apparatus. The residence time depends on the content of water (and any organic solvent), ATBS and potassium salt base in the aqueous solution or aqueous suspension SA2. The person skilled in the art can adjust this residence time depending on the composition of the aqueous solution or aqueous suspension SA2 in order to obtain the ATBS.K crystal form.

[0124] The distillation can be carried out in a vertical or horizontal evaporator, preferably in a vertical evaporator.

[0125] The aqueous solution or aqueous suspension SA2 can flow co-currently or counter-currently to the steam generated by the evaporation, preferably counter-currently to the steam in the distillation apparatus. In other words, the aqueous solution or aqueous suspension SA2 preferably enters the distillation apparatus (preferably an evaporator) in a co-current or counter-current manner to the distillation solvent.

[0126] The aqueous solution or aqueous suspension SA2 can be circulated in one or more evaporators in series, preferably in a single evaporator, before obtaining the suspension S1.

[0127] The absolute pressure during the distillation (1 mbar = 100 Pa) is preferably between 1 and 700 mbar (not including 700 mbar), more preferably below 700 mbar, further preferably below 600 mbar, particularly preferably below 500 mbar, more further preferably below 400 mbar, especially preferably below 300 mbar, particularly preferably below 200 mbar, most preferably below 100 mbar, especially preferably below 50 mbar, and preferably above 1 mbar. The absolute pressure corresponds to the pressure value relative to zero pressure (vacuum).

[0128] Generally, the pressure during the distillation is preferably between 10 and 700 mbar, more preferably between 20 and 700 mbar, further preferably between 40 and 700 mbar, particularly preferably between 50 and 600 mbar, more further preferably between 50 and 500 mbar, especially preferably between 50 and 400 mbar, particularly preferably between 50 and 300 mbar, more preferably between 100 and 700 mbar, further preferably between 200 and 700 mbar, particularly preferably between 500 and 700 mbar, most preferably between 40 and 100 mbar.

[0129] In a particular embodiment, step 2) comprises a step 2') (optional step) of assisting the solvent evaporation. Step 2') is achieved by increasing the temperature of the aqueous solution or aqueous suspension SA2, in other words, the distillation of this step 2') is performed under heating conditions.

[0130] In some embodiments, the aqueous solution or aqueous suspension SA2 is heated during step 2), preferably at a temperature comprised between 5°C and 95°C, more preferably above 10°C and 60°C, further preferably above 20°C and 40°C.

[0131] The heating during the distillation can be achieved by various techniques, including but not limited to: steam heating, hot water heating, electric heating, vapor compression or heat pump heating. Thus, the distillation device can be jacketed so that a heat transfer fluid circulates between the double walls for heating.

[0132] The aqueous solution or aqueous suspension SA2 is preferably heated to a temperature above 5°C and 95°C, more preferably above 10°C and 60°C, further preferably above 20°C and 40°C.

[0133] When the aqueous solution or aqueous suspension SA2 is heated, its temperature is preferably higher than the temperature of step 1).

[0134] The temperature of the aqueous solution or aqueous suspension SA2 is preferably increased at a rate comprised between 0.1 and 10°C / hour, more preferably between 0.2 and 9°C / hour, further preferably between 0.3 and 8°C / hour, in particular between 0.5 and 5°C / hour.

[0135] In certain embodiments, the temperature of the aqueous solution or aqueous suspension SA2 is preferably increased at a rate comprised between 10 and 150°C / hour, more preferably between 30 and 110°C / hour, further preferably between 50 and 100°C / hour, in particular between 60 and 90°C / hour.

[0136] The temperature increase can not be constant throughout the process. For example, the aqueous solution or aqueous suspension SA2 can be heated at a rate of 5°C / hour during the first three hours, then at a rate of 10°C / hour until the final temperature is reached.

[0137] According to another particular embodiment of the application, step 2) can comprise a step 2") (optional step) performed after step 2' or instead of step 2', which improves the productivity and the economic benefits of the process of the application by accelerating the crystallization of ATBS into its potassium salt crystalline form. Step 2") is achieved by decreasing the temperature of the aqueous solution or aqueous suspension SA2.

[0138] The aqueous solution or aqueous suspension SA2 is preferably cooled to a temperature in the range of 5°C to below 95°C, more preferably 10°C to below 60°C, further preferably 20°C to below 40°C, particularly preferably 10°C to 40°C.

[0139] In some embodiments, step 2) further comprises a cooling step.

[0140] The cooling step is preferably carried out in the temperature range of 5°C to 95°C, more preferably above 10°C to 60°C, further preferably above 10°C to 40°C.

[0141] In certain embodiments, the temperature of the cooling step is decreased at a rate of 0.1 to 8°C / hour, more preferably 0.2 to 8°C / hour, further preferably 0.3 to 8°C / hour, particularly preferably 0.5 to 5°C / hour.

[0142] In some embodiments, the temperature of the cooling step is preferably below the heating temperature of step 2) and / or step 1).

[0143] In some embodiments, the cooling step is carried out on the aqueous solution or aqueous suspension SA2 and / or the concentrated aqueous solution or aqueous suspension SA2 and / or the suspension S1.

[0144] When the aqueous solution or aqueous suspension SA2 is cooled (step 2"), its temperature is preferably below the temperature of step 2) and optional step 2').

[0145] According to a preferred embodiment, the temperature of step 2") is equal to or below the temperature of step 1).

[0146] In certain embodiments, no organic solvent or aqueous solution is added in step 2") to obtain ATBS.K crystals.

[0147] The temperature of the solution or aqueous suspension SA2 is preferably decreased at a rate of 0.1 to 8°C / hour, more preferably 0.2 to 8°C / hour, further preferably 0.3 to 8°C / hour, particularly preferably 0.5 to 5°C / hour.

[0148] The temperature decrease can not be constant throughout the process. For example, the aqueous solution or aqueous suspension SA2 can be cooled at a rate of 5°C / hour for the first three hours and then at a rate of 8°C / hour until the final temperature is reached.

[0149] During the cooling of the aqueous solution or aqueous suspension SA2, ATBS.K crystals are formed and finally the suspension S1 is obtained.

[0150] In a particular embodiment, pre-obtained ATBS.K crystals can be added in this step to modify the formation process of the suspension S1, the process being called crystal seeding addition, which allows better control of the crystallization temperature, the crystal size, the size distribution, the purity of the final product and possibly the yield. The 2-acrylamid-2-methylpropanesulfonic acid potassium salt crystals added in this way preferably have an X-ray powder diffraction pattern comprising the following 2 theta (± 0.1 °) characteristic peaks: 13.1 °; 14.4°; 16.3°; 19.8°; 23.5°; 24.3°; 26.9°; 27.6°; 29.3°; 30.6°; 31.6°; 34.3°; 36.1 °; 41.7°; 44.6°; 46.7°.

[0151] According to a particular embodiment of the application, the solvent distilled in step 2) can be partially or totally recycled for the formation of the aqueous solution or suspension SA2 of step 1). In other words, the distilled solvent is preferably at least partially recycled into the aqueous solution or suspension SA2.

[0152] According to another particular embodiment of the application, the distilled solvent can be partially or totally recycled, generally for the washing of the ATBS.K crystals obtained after the solid-liquid separation of step 3) in an optional step 4), which can or not comprise a pre-treatment step.

[0153] The suspension S1 obtained preferably comprises between 30% and 80% (weight percentage, based on the total weight of the suspension S1 ) of ATBS.K crystalline form, more preferably between 50% and 60%.

[0154] During step 2), the pH is preferably greater than 10, more preferably greater than 1 1, further preferably greater than 12, particularly preferably between 13 and 14.

[0155] Step 3) of the process for the preparation of ATBS.K crystalline form:

[0156] The ATBS.K crystals contained in the suspension S1 obtained at the end of step 2) are separated by a solid-liquid separation step, obtaining a composition C1.

[0157] The solid-liquid separation step can be carried out using various technologies, including but not limited to: centrifuges, decanters, filter presses, stirred filters, belt filters, disc filters or drum filters. Preferably, the solid-liquid separation is carried out using a centrifuge. The separation can also be carried out by gravity sedimentation.

[0158] Step 3) is preferably carried out at a temperature ranging from -20°C to 40°C, more preferably from -5°C to 30°C.

[0159] After the solid-liquid separation of step 3) is completed, the 2-acrylamid-2-methylpropanesulfonic acid potassium salt crystals are preferably not subjected to a drying treatment.

[0160] The content of the 2-acrylamido-2-methylpropanesulfonic acid potassium salt crystals in the composition C1 obtained by separation is preferably from 40% to 99% (based on the total weight of the composition C1), more preferably from 60% to 99%, further preferably from 60% to 98%, and particularly preferably from 80% to 99%. The remainder of the composition C1 can comprise water and / or dissolved ATBS.K, and the potassium salt base introduced in step 1).

[0161] At the end of this step 3), the crystals are characterized as ATBS.K crystals.

[0162] In particular embodiments, all or part of the liquid phase obtained after the solid-liquid separation can be used in the aqueous solution or aqueous suspension SA2 of step 1).

[0163] During step 4), the pH is preferably controlled between 6 and 14, more preferably between 8 and 14, further preferably between 10 and 14, particularly preferably between 12 and 14, and most preferably between 13 and 14.

[0164] Step 4) of the process for the preparation of the ATBS.K crystal form:

[0165] In the optional step 4), the composition C1 obtained at the end of step 3) comprising ATBS.K crystals is washed using a washing solution.

[0166] The washing solution can be water, an aqueous solution of a potassium salt base (saturated or non-saturated), or a solution of 2-acrylamido-2-methylpropanesulfonic acid potassium salt (saturated or non-saturated, preferably in the ATBS.K crystal form), more preferably an ATBS.K saturated solution.

[0167] Examples of potassium salt base solutions include solutions of potassium hydroxide, potassium carbonate, potassium bicarbonate or mixtures thereof.

[0168] The washing solution can comprise one or more organic solvents.

[0169] The amount of organic solvent can be adjusted according to the temperature and the content of 2-acrylamido-2-methylpropanesulfonic acid potassium salt or potassium salt.

[0170] Preferably, the washing solution does not contain an organic solvent.

[0171] As mentioned in step 1), the organic solvent is preferably chosen from organic acids, amides, alcohols, ketones, ethers, esters, alkanes, halogenated hydrocarbon compounds, nitriles or mixtures thereof, more preferably from acrylonitrile, isopropyl alcohol, acetic acid or mixtures thereof, and most preferably is acrylonitrile.

[0172] In particular embodiments, the washing is performed by spraying the washing solution on the composition C1.

[0173] In another particular embodiment, the washing is carried out by suspending the composition C1 in a washing solution.

[0174] The weight ratio of the washing solution to the composition C1 obtained at step 3) is preferably comprised between 0.05:1 and 10:1, more preferably between 0.1 :1 and 5:1.

[0175] The washing step is preferably carried out at a temperature ranging from -5 to 40°C, more preferably from 0 to 30°C. The person skilled in the art knows how to adjust the temperature in order to avoid the dissolution of the ATBS.K crystals.

[0176] The ATBS.K crystals obtained at the end of this optional step 4) can be separated from the washing solution by a solid-liquid separation step, leading to a composition C2.

[0177] The solid-liquid separation step can be achieved using various techniques, including but not limited to: vertical or horizontal centrifuges, decanters, filter presses, belt filters, disc filters, pusher filters or rotary drum filters. The separation can also be achieved by gravity settling.

[0178] In a particular embodiment, all or part of the recovered washing solution can be reused in step 4), with or without pre-treatment.

[0179] In another particular embodiment, all or part of the recovered washing solution can be used in the aqueous solution or in the aqueous suspension SA2 of step 1), with or without pre-treatment.

[0180] The pH of the washing solution of step 4) is preferably controlled between 6 and 14, more preferably between 8 and 14.

[0181] Step 5) of the process for the preparation of the ATBS.K crystalline form:

[0182] In the optional step 5), the composition C1 obtained at the end of step 3) or the composition C2 obtained at the end of step 4) is dried.

[0183] The drying step can be achieved using various techniques, including but not limited to: all convective, conductive or radiative drying techniques (fluidized bed dryers, through bed dryers, conveyor belt drying, microwave drying, heated agitated filters, high frequency radiation, infrared radiation, spray drying).

[0184] The drying operation can be carried out under atmospheric pressure or under vacuum.

[0185] The drying step can be carried out in batch (batch drying) or continuously.

[0186] Other steps of the process for the preparation of the ATBS.K crystalline form:

[0187] At least one polymerization inhibitor can be introduced throughout the production process (i.e. during steps 1) to 5) ) to prevent possible polymerization of ATBS or its salts. The inhibitor can be chosen, without limitation, from the group consisting of: hydroquinone, p-methoxyphenol, phenothiazine, 2,2,6,6-tetramethyl(piperidin-1-yl)oxyl, 4-hydroxy-2,2,6,6-tetramethyl(piperidin-1-yl)oxyl, a phenylenediamine derivative or mixtures thereof.

[0188] Preferably, p-methoxyphenol or 4-hydroxy-2,2,6,6-tetramethyl(piperidin-1-yl)oxyl.

[0189] The amount of inhibitor added is preferably between 0.001% and 5% (weight percentage), more preferably between 0.01% and 1%, relative to the amount of ATBS introduced in step 1).

[0190] The inhibitor can be added at any one or more steps of the process, preferably in addition in step 1). More preferably, the inhibitor is part of the aqueous solution SA1 or of the aqueous solution / suspension SA2 introduced in step 1).

[0191] The production process (steps 1) to 5)) can be carried out in continuous or in batch (batch production).

[0192] Polymer

[0193] The present application also relates to the use of the new ATBS.K crystal form in the production of polymers.

[0194] The present application therefore also relates to a polymer made at least from ATBS, wherein the ATBS is at least partially in the ATBS.K crystal form whose X-ray powder diffractogram has characteristic peaks at the following 2 theta angles (±0.1°): 13.1°, 14.4°, 16.3°, 19.8°, 23.5°, 24.3°, 26.9°, 27.6°, 29.3°, 30.6°, 31.6°, 34.3°, 36.1°, 41.7°, 44.6°, 46.7°.

[0195] The polymer is at least partially derived from the ATBS.K crystal form and preferably also comprises at least one other monomer chosen from the group consisting of: a hydrophilic non-ionic monomer, a hydrophilic anionic monomer (other than the ATBS.K crystal form), a hydrophilic cationic monomer, a hydrophilic zwitterionic monomer and a hydrophobic monomer.

[0196] It can therefore be a copolymer or a homopolymer of a plurality of different monomers.

[0197] Preferably, at least 10 mol%, more preferably at least 30 mol%, further preferably at least 50 mol%, particularly preferably at least 70 mol% of the ATBS used to prepare the polymer is ATBS.K crystal form. Most preferably, 100 mol% of the ATBS used is ATBS.K crystal form.

[0198] The polymer preferably comprises 1 to 100 mol% of ATBS, more preferably 2 to 60 mol%, further preferably 3 to 25 mol%. At least 10 mol%, more preferably at least 30 mol%, further preferably at least 50 mol%, particularly preferably at least 70 mol% of the ATBS is ATBS.K crystal form. Most preferably, 100 mol% of the ATBS used is ATBS.K crystal form.

[0199] In particular embodiments, the polymer preferably comprises at least 10 mol% of ATBS, more preferably at least 20 mol%, further preferably at least 30 mol%, particularly preferably at least 40 mol%, especially preferably at least 50 mol%, further more preferably at least 60 mol%, particularly preferably at least 70 mol%, most preferably at least 80 mol%, especially preferably at least 90 mol%. At least 10 mol%, more preferably at least 30 mol%, further preferably at least 50 mol%, particularly preferably at least 70 mol% of the ATBS is ATBS.K crystal form, most preferably 100% of the ATBS used is ATBS.K crystal form.

[0200] In particular embodiments, the polymer is an ATBS homopolymer, and at least 10 mol%, more preferably at least 30 mol%, further preferably at least 50 mol%, particularly preferably at least 70 mol% of the ATBS is ATBS.K crystal form, most preferably 100% of the ATBS used is ATBS.K crystal form.

[0201] In particular embodiments, the polymer is an ATBS.K crystal form homopolymer.

[0202] In particular embodiments, the polymer is prepared from ATBS, at least 10 mol% of which is preferably ATBS.K crystal form, and at least one non-ionic monomer.

[0203] Polymer composition

[0204] The polymer is prepared from ATBS.K crystal form, and preferably further comprises at least one other monomer, which can be selected from the group consisting of: hydrophilic non-ionic monomers and / or hydrophilic anionic monomers and / or hydrophilic cationic monomers and / or hydrophilic zwitterionic monomers and / or hydrophobic monomers and mixtures thereof. It can be a copolymer or a homopolymer of a plurality of different monomers.

[0205] Preferably, the hydrophilic non-ionic monomers which can be employed in the present application are selected in particular from the group comprising water-soluble vinyl monomers such as acrylamide, methacrylamide, N-alkyl acrylamides, N-alkyl methacrylamides, N,N-dialkyl acrylamides (for example N,N-dimethyl acrylamide or N,N-diethyl acrylamide), N,N-dialkyl methacrylamides, alkoxylates of acrylic acid, N-vinylpyrrolidone, N-hydroxymethyl (meth) acrylamide, N-vinyl caprolactam, N-vinyl formamide (NVF), N-vinyl acetamide, N-vinylimidazole, N-vinyl succinimide, acryloyl morpholine (ACMO), glycidyl methacrylate, vinyl acetate, glyceryl methacrylate, bis-acetone acrylamide, methacrylic anhydride, acrylonitrile, maleic anhydride, itaconamide, hydroxyalkyl (meth) acrylate, thioalkyl (meth) acrylate, prenol and its alkoxy derivatives, hydroxyethyl methacrylate and its alkoxy derivatives, hydroxypropyl acrylate and its alkoxy derivatives, and mixtures thereof. In the non-ionic monomers, the alkyl groups are preferably C1-C5, more preferably C1-C3, and are preferably straight-chain alkyl groups. The hydrophilic non-ionic monomer is preferably acrylamide.

[0206] The polymer preferably comprises from 0 to 99 mol% of the hydrophilic non-ionic monomer, more preferably from 40 to 98 mol%, further preferably from 75 to 97 mol%.

[0207] Preferably, the hydrophilic anionic monomers which can be employed in the present application, in addition to the ATBS.K crystal form, can be selected from a wide range of materials. These monomers can have a vinyl functionality (preferably acrylic acid, maleic acid, fumaric acid, malonic acid, itaconic acid or allyl) and comprise a carboxylate, phosphonate, phosphate, sulphate or sulphonate group, or other anionic charge group. Examples of suitable monomers include: acrylic acid; methacrylic acid; dimethacrylic acid; itaconic acid; C1-C3 half esters of itaconic acid; acryloyl chloride; crotonic acid; maleic acid; fumaric acid; 3-acrylamido-3-methylbutanoic acid; strong acid monomers (for example having a sulphonic or phosphonic functionality) such as vinyl sulphonic acid, vinyl phosphonic acid, allyl sulphonic acid, methallyl sulphonic acid, 2-methylene propane-1,3-disulphonic acid, sulfoethyl methacrylate, sulfopropyl methacrylate, sulfopropyl acrylate, allyl phosphonic acid, ethyleneglycol methacrylic acid phosphonate, 2-acrylamido-2-methylpropane sulphonic acid (ATBS), 2-acrylamido-2-methylpropane disulphonic acid, 3-allyloxy-2-hydroxypropane sulphonic acid, diethylallyl phosphonate, carboxyethyl acrylate; water-soluble salts (such as alkali metal salts (distinguished from the ATBS.K crystal form), alkaline earth metal salts or ammonium salts) of these monomers; and mixtures thereof. The hydrophilic anionic monomer is preferably acrylic acid and / or a salt thereof.

[0208] The polymer preferably comprises 0 to 99 mol% of the hydrophilic anionic monomer (in addition to the ATBS.K crystal form), more preferably 5 to 70 mol%, further preferably 10 to 50 mol%. When the content is higher than 5 mol%, these percentages also include the ATBS.K crystal form monomer according to the present application.

[0209] In particular embodiments, the hydrophilic anionic monomer in addition to the ATBS.K crystal form can be salified.

[0210] By salification is meant the replacement of the proton of at least one -R a (=0)-OH type acid function (R represents P, S or C) of the anionic monomer by a metal or ammonium cation, forming a -R a (=0)-OX type salt (X is a metal cation or an organic cation). In other words, the non-salified form corresponds to the acid form of the monomer, for example the R b -C(=0)-OH form; while the salified form of the monomer corresponds to the R b -C(=0)-O-X + form, in which X + corresponds to an alkali metal cation or an organic cation. The salification of the branched water-soluble polymer acid function can be partial or total. The salified form preferably corresponds to a salt of an alkali metal (Li, Na, K, etc.), an alkaline earth metal (Ca, Mg, etc.) or an ammonium (for example ammonium ion or tertiary ammonium), with a potassium salt being preferred.

[0211] The salification can be carried out before, during or after polymerization.

[0212] In particular embodiments, the polymer preferably comprises 1 to 100 mol% of the salified hydrophilic anionic monomer, more preferably 50 to 100 mol%. These percentages include the ATBS.K crystal form monomer according to the present application.

[0213] Preferably, the hydrophilic cationic monomers that can be used according to the application are chosen from monomers derived from vinyl-type units (preferably acrylamides, acrylic acids, allyl or maleic acids) that bear a phosphonium or quaternary ammonium function. Mention can be made, without limitation, of: diallyldialkylammonium salts, such as diallyldimethylammonium chloride (DADMAC); acidified or quaternary ammonium salts of dialkylaminoalkyl (meth)acrylamides, for instance methacrylamidopropyltrimethylammonium chloride (MAPTAC), acrylamidopropyltrimethylammonium chloride (APTAC); acidified or quaternary ammonium salts of dialkylaminoalkyl acrylates, such as quaternized or salted dimethylaminoethyl acrylate (DMAEA); acidified or quaternary ammonium salts of dialkylaminoalkyl methacrylates, such as quaternized or salted dimethylaminoethyl methacrylate (DMAEMA); acidified or quaternary ammonium salts of N,N-dimethylallylamine; acidified or quaternary ammonium salts of diallylmethylamine; acidified or quaternary ammonium salts of diallylamine; vinylamines obtained by hydrolysis (basic or acid) of an amide group -N(R2)-CO-R1 (R1 and R2 being independently a hydrogen atom or an alkyl chain of 1 to 6 carbons), for instance the vinylamine resulting from the hydrolysis of formamide vinylamide; vinylamines obtained by Hofmann degradation; and mixtures thereof. Preferentially, the alkyl groups are C1-C7, more preferentially C1-C3, and can be linear, cyclic, saturated or unsaturated chains. Preferentially, the quaternized dimethylaminoethyl acrylate.

[0214] The person skilled in the art knows how to prepare quaternized monomers, for instance using a quaternizing agent of the R-X type (in which R is an alkyl group and X is a halogen or a sulfate).

[0215] "Quaternizing agent" means a molecule capable of alkylating a tertiary amine.

[0216] The quaternizing agent can be chosen from dialkyl sulfates containing from 1 to 6 carbon atoms or alkyl halides containing from 1 to 6 carbon atoms. Preferentially, the quaternizing agent is chosen from methyl chloride, benzyl chloride, dimethyl sulfate or diethyl sulfate. Furthermore, the application also encompasses DADMAC, APTAC and MAPTAC monomers for which the counterion is sulfate, fluoride, bromide or iodide (instead of chloride).

[0217] The polymer preferably comprises from 0 to 20 mol% of hydrophilic cationic monomers, more preferentially from 0 to 6 mol%.

[0218] Preferably, the hydrophilic zwitterionic monomer can be a derivative of a vinyl type unit (preferably acrylamide, acrylic acid, allyl or maleic acid) which simultaneously bears a quaternary amine or ammonium function and a carboxylic acid (or carboxylate), sulfonic acid (or sulfonate) or phosphoric acid (or phosphate) function. One can in particular and in a non-limiting manner mention dimethylaminoethyl acrylate derivatives such as 2-((2-(acryloyloxy)ethyl)dimethylammonio)ethane-1 -sulfonate, 3-((2-(acryloyloxy)ethyl)dimethylammonio)propane-1 -sulfonate, 4-((2-(acryloyloxy)ethyl)dimethylammonio)butane-1 -sulfonate, [2-(acryloyloxy)ethyl](dimethylammonio)acetate; dimethylaminoethyl methacrylate derivatives such as 2-((2-(methacryloyloxy)ethyl)dimethylammonio)ethane-1 -sulfonate, 3-((2-(methacryloyloxy)ethyl)dimethylammonio)propane-1 -sulfonate, 4-((2-(methacryloyloxy)ethyl)dimethylammonio)butane-1 -sulfonate, 2-(methacryloyloxy)ethyl](dimethylammonio)acetate; dimethylaminopropyl acrylamide derivatives such as 2-((3-acrylamidopropyl)dimethylammonio)ethane-1 -sulfonate, 3-((3-acrylamidopropyl)dimethylammonio)propane-1 -sulfonate, 4-((3-acrylamidopropyl)dimethylammonio)butane-1 -sulfonate, [3-(acryloyloxy)propyl](dimethylammonio)acetate; dimethylaminopropyl methacrylamide derivatives such as 2-((3-methacrylamidopropyl)dimethylammonio)ethane-1 -sulfonate, 3-((3-methacrylamidopropyl)dimethylammonio)propane-1 -sulfonate, 4-((3-methacrylamidopropyl)dimethylammonio)butane-1 -sulfonate and [3-(methacryloyloxy)propyl](dimethylammonio)acetate; and mixtures thereof.

[0219] Other hydrophilic zwitterionic monomers can also be used, in particular those described by the Applicant in document WO 2021 / 123599.

[0220] The polymer preferably comprises from 0 to 20 mol% of hydrophilic zwitterionic monomer, more preferably from 0 to 10 mol%.

[0221] Partition coefficient K ow Hydrophobic monomers having a partition coefficient K greater than 1 can also be used to prepare the polymer of the application. These monomers are preferably chosen from the following list: (meth)acrylates having (i) C4-C 30 alkyl, (ii) aralkyl (C4-C 30 alkyl, C4-C 30 aryl), (iii) propoxylated, (iv) ethoxylated or (v) ethoxylated and propoxylated chains; alkyl aryl sulfonates (C4-C 30alkyl, C4-C 30 aryl); with (i) C4-C 30 alkyl, (ii) aralkyl (C4-C 30 alkyl, C4-C 30 aryl), (iii) propoxylated, (iv) ethoxylated or (v) ethoxylated and propoxylated chains, mono- or di-substituted (meth)acrylamides; anionic or cationic monomer derivatives of (meth)acrylamides or (meth)acrylic acid with hydrophobic chains; vinylpyridine; and mixtures thereof. The hydrophobic monomers can comprise halogen atoms, for example chlorine atoms.

[0222] Among these hydrophobic monomers:

[0223] alkyl, preferably C4-C 20 , more preferably C4-C8. Among these, C6-C 20 alkyl is preferably linear, C4-C5 alkyl is preferably branched;

[0224] aralkyl, preferably C7-C 25 , more preferably C7-C 15 ;

[0225] ethoxylated chains preferably comprise from 1 to 200 -CH2-CH2-O- groups, more preferably from 6 to 100, further preferably from 10 to 40;

[0226] propoxylated chains preferably comprise from 1 to 50 -CH2-CH2-CH2-O- groups, more preferably from 1 to 20.

[0227] Preferred hydrophobic monomers belonging to these classes include, for example:

[0228] n-hexyl (meth)acrylate, n-octyl (meth)acrylate, octyl (meth)acrylamide, lauryl (meth)acrylate, lauryl (meth)acrylamide, myristyl (meth)acrylate, myristyl (meth)acrylamide, pentadecyl (meth)acrylate, pentadecyl (meth)acrylamide, cetyl (meth)acrylate, cetyl (meth)acrylamide, oleyl (meth)acrylate, oleyl (meth)acrylamide, erucyl (meth)acrylate, erucyl (meth)acrylamide, N-tert-butyl (meth)acrylamide, 2-ethylhexyl acrylate, C4-C 22 itaconic acid half-esters, C4-C 22 acidified or quaternary ammonium salts of dialkylaminoalkyl (meth)acrylates, C4-C 22 acidified or quaternary ammonium salts of dialkylaminoalkyl (meth)acrylamides, vinylpyridine, acrylamidoundecanoic acid, and mixtures thereof;

[0229] Cationic allyl derivatives of formula (I) or (II):

[0230]

[0231] wherein:

[0232] R: independently an alkyl chain containing from 1 to 4 carbon atoms;

[0233] R1: an alkyl or aralkyl chain containing from 8 to 30 carbon atoms;

[0234] X: selected from bromide, chloride, iodide, fluoride and any halide with a negatively charged counterion;

[0235] and preferably, the (meth)acryl type hydrophobic cationic derivative according to formula (III):

[0236]

[0237] wherein:

[0238] - A represents O or N-R5 (preferably A represents N-R5);

[0239] - R2, R3, R4, R5, R6, R7: independently hydrogen or an alkyl chain containing from 1 to 4 carbon atoms;

[0240] - Q: an alkyl chain containing from 1 to 20 carbon atoms;

[0241] - R8: an alkyl or aralkyl chain containing from 8 to 30 carbon atoms;

[0242] - X: selected from bromide, chloride, iodide, fluoride and any halide with a negatively charged counterion.

[0243] When the polymer is water soluble, it preferably comprises less than 5 mol% of hydrophobic monomers and the amount thereof is adjusted to ensure that the polymer remains water soluble.

[0244] The present application can also use monomers having a fluorescent functionality. The fluorescent functionality monomers can be detected by any suitable method, for example by fluorescence measurement using a fixed wavelength fluorimeter. Typically, the fluorescent functionality monomers are detected at their excitation and emission maxima, which can be determined by scanning fluorimetry.

[0245] The fluorescent functional monomer can be selected from the group consisting of sodium or potassium styrenesulfonate, styrenesulfonic acid, vinylimidazole and derivatives thereof, 9-vinylanthracene and derivatives thereof, N-9-xanthenylallylacetamide and derivatives thereof, allyldibenzosuberenol and derivatives thereof, chinaldine and derivatives thereof, quinophthalone and derivatives thereof, chinaldionone and derivatives thereof, N,N-dimethyl-N-[3-[N'-(4-methoxynaphthalimidyl)]propyl-N-(2-hydroxy-3-allyloxy)propylammonium hydroxide, and mixtures thereof.

[0246] Other fluorescent compounds can also be used after functionalization with an allyl, vinyl or acrylic double bond, such as, for example: pyranine and derivatives thereof, coumarin and derivatives thereof, quinolaxine and derivatives thereof, pinacyanol and derivatives thereof, xanthene and derivatives thereof, DABSYL and derivatives thereof, 3-hydroxy-2-methylene-3-(1-naphthyl)propionic acid and derivatives thereof, rhodamine and derivatives thereof, N-dibenzoazolylallylacetamide and derivatives thereof, naphthalene derivatives, fluorescein and derivatives thereof, pyrene and derivatives thereof, indolyl carbonyl and derivatives thereof, pyrazoline and derivatives thereof, and mixtures thereof.

[0247] In a preferred embodiment, the polymer does not comprise a monomer comprising a fluorescent functional group.

[0248] In a particular embodiment, the polymer can comprise at least one cyclic monomer having a hydrolysable functional group. Preferably, said cyclic monomer having a hydrolysable functional group is selected from the group consisting of cyclic enone acetal, thiolactone and mixtures thereof.

[0249] Said cyclic enone acetal is preferably selected from the group consisting of 2-methylene-1,3-dioxepane (MDO), 5,6-benzo-2-methylene-1,3-dioxepane (BMDO), 2-methylene-4-phenyl-1,3-dioxolane (MPDL), 2-methylene-1,3,6-trioxocane (MTC), and mixtures thereof, preferably 2-methylene-1,3-dioxepane (MDO).

[0250] Said thiolactone is preferably selected from the group consisting of dibenzo[c,e]oxepin-7H-5-thione (DOT), ε-thiolactone, 3,3-dimethyl-2,3-dihydro-5H-benzo[e][1,4]dioxepin-5-thione (DBT), and mixtures thereof, preferably 3,3-dimethyl-2,3-dihydro-5H-benzo[e][1,4]dioxepin-5-thione.

[0251] In a particular embodiment, the polymer can comprise at least one group having a LCST (Lower Critical Solution Temperature).

[0252] As is generally understood by those skilled in the art, a group with LCST (lowest concentration of water) refers to a group whose water solubility at a specific concentration changes above a certain temperature and with varying salinity. This group has a heating transition temperature, which defines its lack of affinity for the solvent medium. Lack of affinity for the solvent leads to emulsification or loss of transparency in the medium, which may be due to precipitation, aggregation, gelation, or increased viscosity. The lowest point of this transition temperature is called the LCST. For each concentration of the LCST group, a heating transition temperature can be observed that is higher than the LCST (the lowest point on the curve). Below this temperature, the polymer is soluble in water; above this temperature, the polymer loses its water solubility.

[0253] In a particular embodiment, the polymer may contain at least one group having a UCST (maximum critical dissolution temperature).

[0254] As is generally understood by those skilled in the art, a group with UCST (Unified Cooling Transition Temperature) refers to a group whose water solubility at a specific concentration changes below a certain temperature and with varying salinity. This group possesses a cooling transition temperature, which defines its lack of affinity for the solvent medium. This lack of affinity for the solvent leads to emulsification or loss of transparency in the medium, which may be due to precipitation, aggregation, gelation, or increased viscosity. The highest point of this transition temperature is called the UCST. For each concentration of the UCST group, a cooling transition temperature can be observed below the UCST (the highest point on the curve). Above this temperature, the polymer is soluble in water; below this temperature, the polymer loses its water solubility.

[0255] Those skilled in the art will adjust the amount of different monomers to ensure that the total amount of monomers does not exceed 100 mol when preparing the polymer of the present invention.

[0256] According to the present invention, the polymer may have a linear, branched, crosslinked, star-shaped, or comb-shaped structure. This structure can be achieved by selecting an initiator, chain transfer agent, polymerization techniques (such as reversible addition-fragmentation chain transfer (RAFT) polymerization, nitrile-oxygen mediated polymerization (NMP), or atom transfer radical polymerization (ATRP)), and introducing or controlling the concentration of structural monomers, which is conventional technical knowledge for those skilled in the art.

[0257] This polymer can also be structured using branching agents. Structured polymers are nonlinear polymers with side chains that, when dissolved in water, form highly entangled structures, resulting in extremely high low-gradient viscosity.

[0258] Preferably, the branching agent is selected from the following categories:

[0259] - a structurant: can be chosen from the group comprising polyethylenically unsaturated monomers (having at least two unsaturated functions, such as vinyl functions, in particular allyl or acrylic functions), such as methylenebisacrylamide (MBA), triallylamine, tetraallylammonium chloride or 1,2-dihydroxyethylenebis(N-acrylamide);

[0260] - a monomer having at least two epoxy functions;

[0261] - a monomer having at least one unsaturated function and one epoxy function;

[0262] - a macroinitiator (such as a polyperoxide, a polyazide) and a transfer agent (such as a polythiol polymer and a polyol);

[0263] - a functionalized polysaccharide;

[0264] - a water-soluble metal complex comprising:

[0265] * a metal having a valence greater than 3 (such as, but not limited to, aluminum, boron, zirconium or titanium);

[0266] * a ligand bearing a hydroxyl function.

[0267] The content of branching agent in the polymer is preferably less than 40,000 ppm (weight ratio) of the total weight of the polymer monomers, more preferably less than 10,000 ppm, most preferably less than 5,000 ppm.

[0268] In particular embodiments, the content of branching agent is at least 0.1 ppm, preferably at least 1 ppm, more preferably at least 10 ppm, further preferably at least 100 ppm, in particular at least 1,000 ppm, of the total weight of the polymer monomers.

[0269] When the polymer is water-soluble and contains a branching agent, the polymer can retain water-soluble properties. The skilled person is able to achieve this by adjusting the amount of branching agent and, if necessary, adding a transfer agent.

[0270] In a preferred aspect, the polymer is a water-soluble polymer that does not contain a branching agent. In particular embodiments, the polymer can comprise a transfer agent.

[0271] Suitable transfer agents include, but are not limited to, methanol; isopropanol; sodium hypophosphite; calcium hypophosphite; magnesium hypophosphite; potassium hypophosphite; ammonium hypophosphite; formic acid; sodium formate; calcium formate; magnesium formate; potassium formate; ammonium formate; 2-mercaptoethanol; 3- mercapto-propanol; dithiopropanol; thioglycerol; mercaptoacetic acid; mercapto- propionic acid; mercapto-lactic acid; mercapto-malic acid; cysteine; aminoethyl mercaptan; mercapto-acetate; allyl phosphite; allyl mercaptans (e.g., n-dodecyl mercaptan); sodium methylallyl sulfonate; calcium methylallyl sulfonate; magnesium methylallyl sulfonate; potassium methylallyl sulfonate; ammonium methylallyl sulfonate; alkyl phosphites (e.g., tri(C 12 -C 15 )alkyl phosphites, dioleyl hydrogen phosphite, dibutyl phosphite); dialkyl dithiophosphates (e.g., dioctyl phosphonate); t-nonyl mercaptan; 2-ethylhexyl mercaptoacetate; n-octyl mercaptan; n-dodecyl mercaptan; t-dodecyl mercaptan; iso-octyl mercaptoacetate; 2-ethylhexyl mercaptoacetate; 2-ethylhexyl mercaptoacetate; polythiols; and mixtures thereof. Sodium hypophosphite or sodium formate is preferred.

[0272] The amount of transfer agent in the polymer is preferably from 0 to 100,000 ppm (w / w) of the total weight of the monomers of the polymer, more preferably from 0 to 10,000 ppm, even more preferably from 0 to 1,000 ppm, and especially from 0 to 100 ppm. When present, the amount of transfer agent is at least 0.1 ppm, and preferably at least 1 ppm, of the total weight of the monomers of the polymer.

[0273] In certain embodiments, the polymer is free of transfer agent.

[0274] Generally, no special polymerization methods need to be developed for the polymer. Indeed, the polymer can be prepared using any polymerization technique well known to those skilled in the art, including: solution polymerization; gel polymerization; precipitation polymerization; (normal or reverse phase) emulsion polymerization; suspension polymerization; reactive extrusion polymerization; water-in-water polymerization; micellar polymerization; and the like.

[0275] The polymerization is generally carried out by free radical polymerization, preferably by reverse phase emulsion polymerization or gel polymerization. Free radical polymerization includes conventional free radical polymerization using UV, azo initiators, redox initiators or thermal initiators, as well as controlled radical polymerization (CRP) or template polymerization techniques.

[0276] Controlled radical polymerization techniques include, but are not limited to, iodine transfer polymerization (ITP), nitroxide-mediated polymerization (NMP), atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer (RAFT) polymerization, MADIX technology (molecular design via Xanthates exchange), organometallic-mediated radical polymerization (OMRP) in its various variants, and organohetereoatom-mediated radical polymerization (OHRP).

[0277] The polymer can be partially or completely post-hydrolyzed. Post-hydrolysis refers to the hydrolysis reaction that occurs after the monomers have polymerized to form the polymer. The essence of post-hydrolysis is to react the hydrolyzable functional groups (preferably non-ionic functional groups, more preferably amide groups or ester groups) in the monomers with a hydrolysis agent. The hydrolysis agent can be an enzyme, an ion exchange resin, a Bronsted acid (such as a hydrohalic acid) or a Bronsted base (such as an alkali / alkaline earth metal hydroxide), preferably a Bronsted base. During the post-hydrolysis process, the number of carboxylic acid functional groups in the polymer increases as the base reacts with the amide groups or ester groups in the polymer to form carboxylate groups.

[0278] If the preparation process includes a drying step (such as spray drying, drum drying, microwave irradiation drying or fluidized bed drying), the polymer can be in a liquid, gel or solid state.

[0279] The molecular weight of the polymer is preferably at least 0.5 million g / mol (weight average molecular weight), more preferably in the range of 0.5 million to 40 million g / mol, and even more preferably in the range of 5 million to 30 million g / mol. Polymers having a molecular weight in the range of 5,000 to 100,000 g / mol or 100,000 to 500,000 g / mol can also be prepared.

[0280] The molecular weight is determined by the intrinsic viscosity of the polymer. The specific viscosity at different concentrations is first determined using methods known in the art, and the intrinsic viscosity value is obtained by extrapolating the specific viscosity-concentration curve to zero concentration (or calculated using the least square method). The molecular weight is then calculated using the Mark-Houwink equation:

[0281] [η] = K.M α

[0282] wherein:

[0283] [η] represents the intrinsic viscosity of the polymer determined by solution viscosity method;

[0284] K is an empirical constant;

[0285] M represents the molecular weight of the polymer;

[0286] a is the Mark-Houwink coefficient.

[0287] The values of K and a depend on the specific polymer-solvent system.

[0288] Polymer properties

[0289] When the polymer is water-soluble, its filtration ratio (FR for short) is preferably less than 1.5, more preferably less than 1.3, and most preferably less than 1.1.

[0290] In this article, "filtration ratio" refers to a test method used to evaluate the performance of polymer solutions by simulating the permeability of a deposit layer. This test is achieved by measuring the time required for a specific volume / concentration of solution to flow through a filter. The FR value is typically calculated by comparing the filtration performance of a polymer solution for two consecutive equal volumes of filtrate, and its value reflects the tendency of the solution to clog the filter—a lower FR value indicates better performance.

[0291] The FR determination method is as follows: Prepare a 1000 ppm (by weight) polymer solution and measure the time required for a specific volume of solution to flow through a filter. The test unit maintains a pressure of 2 bar, and the filter has a diameter of 47 mm and a calibrated pore size (typically using a 1.2 μm, 3 μm, 5 μm, or 10 μm pore size membrane). Record the time required for 100 ml (t) of filtered solution to flow through the filter. 100ml ), 200ml (t) 200ml ) and 300ml (t 300ml The required time is calculated using the following formula to determine the filtration ratio:

[0292] [Mathematical Expression 2]

[0293]

[0294] Time measurement is accurate to 0.1 seconds.

[0295] The filtration ratio (FR) characterizes the tendency of a polymer solution to clog a filter caused by two consecutive equal volumes of filtrate.

[0296] Compared with polymers of the same molecular weight prepared from amorphous ATBS.K, the polymers used in this invention have superior resistance to chemical and thermal degradation.

[0297] Chemical degradation resistance test method:

[0298] Under aerobic conditions, a polymer solution of a specific concentration was prepared in a saline solution with a specified mineralization, and then brought into contact with chemical pollutants such as iron or hydrogen sulfide. The viscosity of the solution was measured before and 24 hours after exposure to the pollutants, with all viscosity tests conducted under the same temperature and shear gradient conditions.

[0299] Test method for resistance to mechanical degradation:

[0300] Under anaerobic conditions (such as an inert glove box protected by nitrogen), a polymer solution of a specific concentration was prepared in a brine solution of a designated component and placed in a stainless steel aging tank at a set temperature for a predetermined aging time. The aging tank was then cooled to room temperature, and the viscosity of the solution was measured and compared with the initial value. All operations were performed within the glove box to avoid oxygen contact, and the stainless steel aging tank was completely sealed to ensure that oxygen could not penetrate during the thermal aging process. Viscosity measurements before and after aging were performed within the glove box under the same temperature and velocity gradient conditions.

[0301] The resistance to chemical and thermal degradation is quantified by the rate of viscosity loss (expressed in percentage) calculated as follows:

[0302] [Equation 3]

[0303]

[0304] Method for treating a water suspension of solid particles

[0305] The Applicant has surprisingly found that the use of water-soluble polymers prepared from ATBS.K crystals allows to significantly improve the efficiency of the treatment of suspensions, in particular in terms of:

[0306] - increasing the sludge concentration at the outlet of the thickener;

[0307] - the dewatering step and the step of drying and solidification of the suspension when it is discharged to the ground;

[0308] - the mechanical treatment of the treated suspension

[0309] Accordingly, the present application relates to a method for treating a water suspension of solid particles, characterized in that said suspension is brought into contact with at least one water-soluble polymer prepared from ATBS.K crystals. The treatment method is achieved by mixing the suspension with the water-soluble polymer.

[0310] Such treatment can be carried out in a thickener (typically a cylindrical retention zone with a conical bottom, having a diameter of several meters). In a particular embodiment, the aqueous suspension is conveyed through a pipe to the thickener, and the water-soluble polymer is added in the pipe.

[0311] In another embodiment, the water-soluble polymer is added directly into the thickener already containing the suspension to be treated. In a typical mineral treatment process, the suspension is concentrated in the thickener, which finally forms a high-density sludge (discharged from the bottom) and a treated suspension-released aqueous fluid (called clear liquid, which overflows from the top). The addition of the water-soluble polymer allows to effectively increase the sludge concentration and to enhance the clear liquid clarity.

[0312] In yet another embodiment, the water-soluble polymer is added during the conveying of the particulate suspension through a pipe to a deposition zone. Preferably, the polymer is injected into the conveying pipe, and the treated suspension is spread in the deposition zone for dewatering and solidification. These deposition zones can be open-air sites without containment, or they can be closed tanks or cells.

[0313] Typical example of treatment during conveying: after the polymer-treated suspension has been spread on the ground for dewatering and solidification, a second layer of treated suspension is laid on the already solidified layer.

[0314] Another embodiment is a continuous spreading of the water-soluble polymer treated suspension: the treated suspension is continuously dropped onto the previously dropped suspension in the deposition area, thereby forming a treated material body that can be subjected to water extraction.

[0315] In a particular embodiment, the water-soluble polymer is added to the suspension prior to the mechanical treatment, such as centrifugation, filter pressing or filtration. The polymer can be added at different stages of the suspension treatment process, for example both in the pipe conveying the suspension to the thickener and in the slurry leaving the thickener and being conveyed to the deposition area or the mechanical treatment device.

[0316] The water-soluble polymer can be added to the aqueous suspension to be treated in liquid or solid form, for example in the form of an emulsion, preferably a water-in-oil emulsion, an aqueous or multiphase oil-based particulate suspension, or a powder. Preferably, the addition is performed in the form of an aqueous solution prepared from a concentrated form, such as a powder, a water-in-oil emulsion or a multiphase particulate suspension.

[0317] In a particular embodiment, the aqueous multiphase particulate suspension preferably comprises:

[0318] 15 to 60% by mass of at least one water-soluble polymer in the form of solid particles having an average particle size of 5 to 500 μm;

[0319] 15 to 45% by mass of at least one alkali metal salt and / or alkaline earth metal salt;

[0320] a thickener of at least one non-water-soluble polymer;

[0321] at least 10% by mass of water;

[0322] and the Brookfield viscosity of the suspension at 20°C is 500 to 20,000 cps;

[0323] the density is between 1.1 and 2 kg-L"1.

[0324] In another embodiment, the oily multiphase particulate suspension preferably comprises:

[0325] 15 to 60% by mass of at least one water-soluble polymer in the form of solid particles having an average particle size of 5 to 500 μm;

[0326] a thickener of at least one non-water-soluble polymer;

[0327] at least 10% by mass of oil;

[0328] and the Brookfield viscosity of the suspension at 20°C is 500 to 20,000 cps;

[0329] the density is between 0.6 and 1.4 kg-L"1.

[0330] The Brookfield viscosity is measured using a Brookfield viscometer equipped with an LV spindle, at a rotation speed of 30 rpm, preferably at 20°C. The density is measured at 20°C, at 1 atmosphere (i.e. 101,325 Pa).

[0331] When the water-soluble polymer is in solid form, it can be partially or totally hydrated by using a polymer preparation device, such as the polymer slicing unit PSU disclosed in EP 2 203 245.

[0332] In particular embodiments, the water-soluble polymer can be used in combination with at least one other synthetic or natural polymer. These polymers can be added simultaneously or in stages, before and after the addition of the water-soluble polymer. The other polymers can be water-soluble or water-swellable substances, including dispersants, coagulants or flocculants.

[0333] In another embodiment, the water-soluble polymer can be used in combination with salts, such as calcium and / or magnesium salts. The polymer and the salt can be added simultaneously or in stages. Suitable salts include inorganic and organic salts, including in particular: calcium chloride, calcium acetate, calcium sulfate, calcium nitrate, calcium hydroxide, calcium carbonate, magnesium chloride, magnesium acetate, magnesium sulfate, magnesium nitrate, magnesium hydroxide, magnesium carbonate, calcium formate, calcium gluconate, calcium propionate, tricalcium phosphate and calcium succinate.

[0334] The water-soluble polymer is preferably added to the aqueous suspension in an amount of between 50 and 5,000 g per ton of solid particles (dry weight), preferably between 250 and 2,000 g / ton, more preferably between 500 and 1,500 g / ton. The exact amount to be added is determined according to the nature and composition of the suspension to be treated, and can be determined by routine adjustment by a person skilled in the art.

[0335] According to the application, the method can be used to treat suspensions of solid particles, in particular mineral particles. The aqueous suspension of solid particles can comprise various types of sludge, residue or waste, in particular mineral particle suspensions originating from mineral extraction, such as industrial sludge, washing effluents and waste resulting from mining operations (coal mines, diamond mines, phosphate mines, metal mines, etc.). Such suspensions can also result from oil sand extraction processes, such as sludge or extraction residue resulting from oil sand processing. Such suspensions generally contain organic / inorganic particles, such as mixtures with water, for example clays, sediments, sand particles, metal oxides, oils, etc.

[0336] Generally, the suspension of solid particles is concentrated, containing between 5% and 60% by weight of solid particles, preferably between 20% and 50% by weight of solid particles, relative to the total weight of the suspension.

[0337] The process according to the invention is particularly suitable for treating oil sand extraction residues (known as "fine tailings" or "polished fine tailings"), i.e. tailings containing a high amount of clay material; and mature fine tailings (MFT), which are formed over the years by sedimentation and have a higher clay content. The process according to the invention can also be used to treat so-called "fresh" residues, i.e. residues directly resulting from the operation of separating bitumen from the soil in which it is extracted.

[0338] Flocculation process of an aqueous suspension of solid particles

[0339] The present invention also relates to a flocculation process of an aqueous suspension of solid particles, bringing said suspension into contact with at least one water-soluble polymer prepared from an ATBS.K crystalline form having an X-ray powder diffraction pattern comprising the following 2 theta (± 0.1°) characteristic peaks: 13.1°; 14.4°; 16.3°; 19.8°; 23.5°; 24.3°; 26.9°; 27.6°; 29.3°; 30.6°; 31.6°; 34.3°; 36.1°; 41.7°; 44.6°; 46.7°.

[0340] All the preceding embodiments relating to the process for treating an aqueous suspension of solid particles are applicable to the flocculation process of an aqueous suspension of solid particles.

[0341] Method for enhanced hydrocarbon recovery (oil and / or gas)

[0342] The present invention relates to a method for enhanced hydrocarbon (oil and / or gas) recovery, comprising the following steps:

[0343] a) preparing an injection fluid: mixing at least one 2-acrylamido-2-methylpropane sulfonic acid (AMPS) water-soluble polymer with water or brine;

[0344] said 2-acrylamido-2-methylpropane sulfonic acid being in ATBS.K crystalline form before polymerization, having an X-ray powder diffraction pattern comprising the following 2 theta (± 0.1°) characteristic peaks: 13.1°; 14.4°; 16.3°; 19.8°; 23.5°; 24.3°; 26.9°; 27.6°; 29.3°; 30.6°; 31.6°; 34.3°; 36.1°; 41.7°; 44.6°; 46.7°;

[0345] b) injecting the injection fluid into a subterranean formation;

[0346] c) displacing hydrocarbons in the formation by the injection fluid;

[0347] d) recovering an aqueous hydrocarbon mixture.

[0348] When the water-soluble polymer used to formulate the injection fluid is in the form of a powder, the average particle size of the particles is preferably less than 1.5 mm, more preferably less than 850 microns, and suitably greater than 5 microns.

[0349] The average particle size refers to the average of the largest dimension of the particles (e.g. the diameter of a spherical particle). Preferably, a conventional laser measurement device can be used. For example, a Malvern Mastersizer Model MS2000 laser particle size instrument can be used. Such an instrument can determine the particle size distribution in a liquid or solid medium by laser diffraction.

[0350] If the water-soluble polymer is in the form of particles, it can be dissolved in the aqueous medium in a dispersion device. For example, a polymer slicing unit (PSU) as described in US 8,186,871 can be used to prepare a concentrated aqueous solution of the polymer.

[0351] The water or brine used in the injection fluid can be sourced from produced water. "Produced water" refers to all brackish / dilute water, brine, seawater or aquifer water from a hydrocarbon reservoir. According to the patent application WO 2018 / 020175, the produced water can be pre-treated before formulating the injection fluid.

[0352] The water-soluble polymer can be used in combination with a stabilizing compound. These stabilizing compounds (stabilizers) are effective in protecting the polymer from thermal, chemical and / or mechanical degradation. Examples of suitable stabilizers can be found in the patent application WO 2010 / 133258.

[0353] Depending on the process requirements, the polymer-containing injection fluid can be injected alone or in combination with one or more chemical agents for enhanced hydrocarbon recovery. These chemical agents include weak / strong / ultra-strong inorganic or organic bases that can saponify the crude oil and generate surfactants in situ to solubilize hydrocarbons (especially petroleum), such as sodium (potassium) carbonate, caustic soda, borate and metaborate compounds, amines and basic polymers. Another class of compounds that are often co-injected with polymers are surfactants, which are usually anionic, zwitterionic, cationic, and sometimes non-ionic. These compounds are rarely injected in pure form and are usually formulated with co-surfactants and co-solvents to improve their compatibility and effectiveness in the reservoir (subterranean formation).

[0354] The content of the water-soluble polymer in the injection fluid is preferably from 10 to 15,000 ppm (by weight), more preferably from 50 to 10,000 ppm, and particularly preferably from 100 to 5,000 ppm.

[0355] Applicants have unexpectedly discovered that water-soluble polymers prepared from the ATBS.K crystal form have superior filtration and chemical / thermal degradation resistance properties compared to polymers of equivalent molecular weight prepared from the amorphous ATBS.K form. It is well known that the higher the molecular weight of a polymer, the worse the filtration properties. The advantage of the present invention is that it is possible to achieve both ultra-high molecular weight and good filtration properties. In addition, the concentration of polymer required to achieve a target viscosity is significantly reduced, thereby improving the economics of hydrocarbon (oil and / or gas) recovery.

[0356] The key role of the water-soluble polymer in the present invention is to increase viscosity - to achieve mobility control by increasing the viscosity of the aqueous phase injected into a hydrocarbon reservoir (subterranean rock formation) without the need for chemical cross-linking (i.e. inter-chain bridging).

[0357] In particular embodiments, the method of enhancing hydrocarbon (oil and / or gas) recovery comprises the steps of:

[0358] a) Formulating an injection fluid: the fluid comprises a water-soluble polymer having a molecular weight greater than 5 million g / mol and satisfies:

[0359] the injection fluid has a salt concentration greater than 100 g / L, with the divalent salt content being no more than 50 g / L;

[0360] the polymer has a 2-acrylamido-2-methylpropanesulfonic acid (AMPS) monomer content of at least 80 mol%, and wherein at least 50 mol% (preferably at least 70 mol%, more preferably 100 mol%) is in the ATBS.K crystal form prior to polymerisation;

[0361] the water-soluble polymer concentration in the injection fluid is less than 3,000 ppm (w / w);

[0362] the injection fluid has an initial viscosity V1 prior to shearing in step b);

[0363] b) subjecting the injection fluid to shearing treatment to reduce its viscosity by more than 25% compared to V1, wherein:

[0364] [mathematical equation 4]

[0365]

[0366] wherein:

[0367] V1 is the viscosity of the injection fluid prior to shearing in step b) at the temperature of the formation;

[0368] V2 is the viscosity of the injection fluid after shearing in step b) at the temperature of the formation;

[0369] V 水 is the viscosity of the water used to formulate the injection fluid at the temperature of the formation;

[0370] c) injecting the injection fluid into a subterranean formation,

[0371] The subterranean formation is a carbonate formation having a permeability of less than 300 millidarcies and a temperature of more than 100°C;

[0372] d) displacing hydrocarbons in the formation by the injection fluid;

[0373] e) recovering the aqueous hydrocarbon (oil and / or gas) mixture.

[0374] The shearing step can be carried out by means of a valve, an orifice plate or a pump.

[0375] The concentration of divalent salts in the injection fluid is preferably comprised between 3 and 50 g / L.

[0376] The carbonate formation is a sedimentary formation having a carbonate content of at least 50%.

[0377] Fracturing fluid

[0378] The present invention relates to a fracturing fluid comprising an aqueous phase, at least one proppant and a water-soluble polymer made from 2-acrylamido-2-methylpropane sulfonic acid in the ATBS.K crystalline form having an X-ray powder diffraction pattern comprising the following 2 theta (± 0.1°) characteristic peaks: 13.1°; 14.4°; 16.3°; 19.8°; 23.5°; 24.3°; 26.9°; 27.6°; 29.3°; 30.6°; 31.6°; 34.3°; 36.1°; 41.7°; 44.6°; 46.7°.

[0379] The aqueous phase is preferably selected from the group consisting of sea water, brine and fresh water, more preferably brine. Brine is a solution consisting of water and organic or inorganic salts, which can comprise monovalent, divalent, trivalent salts and mixtures thereof. Preferably, the brine has a salt content of at least 1,000 mg / L, more preferably at least 5,000 mg / L, further preferably at least 10,000 mg / L, particularly preferably at least 50,000 mg / L, most preferably it is a saturated brine.

[0380] The proppant can be selected from the non-limiting list comprising: sand, ceramic, bauxite, glass beads and resin impregnated sand.

[0381] The content of proppant in the fracturing fluid is preferably comprised between 0.5% and 40%, more preferably between 1% and 25%, particularly preferably between 1.5% and 20% of the total weight of the fracturing fluid.

[0382] The content of water-soluble polymer made from said ATBS.K crystalline form in the fracturing fluid is preferably comprised between 0.001% and 1%, more preferably between 0.002% and 0.2% of the total weight of the fracturing fluid.

[0383] The fracturing fluid can also comprise other compounds known in the art (as described in SPE 152596), for example:

[0384] - clay anti-swelling agents (such as potassium chloride or choline chloride);

[0385] - bactericides for preventing the growth of bacteria, especially sulphate-reducing bacteria, which can form sticky sludge, reducing the surface of the channels, typical examples of which are commonly used, including the most widespread glutaraldehyde, and formaldehyde or isothiazolinone compounds, and / or;

[0386] - oxygen scavengers (such as ammonium bisulphite) for preventing oxidative corrosion damage to the injection tubings and other components, and / or;

[0387] - corrosion protection additives for protecting the tubings from oxidation by residual oxygen, preferably N,N-dimethylformamide, and / or;

[0388] - lubricants, such as petroleum distillates, and / or;

[0389] - iron chelators, such as citric acid, ethylenediaminetetraacetic acid / EDTA, phosphonates, and / or;

[0390] - anti-scaling agents, such as phosphates, phosphonates, polyacrylates or glycols.

[0391] The water-soluble polymer according to the present application can be in various solid or liquid forms before being used in the fracturing fluid, preferably in the form of a powder, a water-in-oil reverse emulsion, an aqueous or oily multiphase granular suspension.

[0392] Process for preparing a fracturing fluid

[0393] The present application also relates to a process for preparing a fracturing fluid, by adding to water or brine at least one water-soluble polymer made from 2-acrylamido-2-methylpropane sulphonic acid in the form of ATBS.K crystalline form (as described previously), and in one of the following forms before forming the fracturing fluid:

[0394] - in the form of a powder;

[0395] - in the form of a water-in-oil reverse emulsion;

[0396] - in the form of an aqueous or oily multiphase granular suspension.

[0397] The process for preparing a fracturing fluid according to the present application preferably comprises the step of adding to the aforementioned fluid at least one proppant, as described previously.

[0398] When the water-soluble polymer added to the fracturing fluid is in the form of a powder before being formulated, the average size of the polymer particles is preferably less than 1.5 mm, more preferably less than 850 μm, particularly preferably less than 200 μm, and advantageously greater than 5 μm.

[0399] The average particle size of the water-soluble polymer particles refers to the average value of the largest dimension of the particles (e.g. the diameter of a spherical particle) and is preferably determined using a laser measurement device (e.g. a Malvern Mastersizer MS2000 laser particle size analyzer) as is routine for the skilled person. Such an instrument can measure the particle size distribution in a liquid or solid medium by laser diffraction.

[0400] When the water-soluble polymer of the application is in a solid form, it can be partially or completely hydrated and dissolved using a polymer preparation device (e.g. a polymer slicing unit PSU as disclosed in EP 2 203 245).

[0401] If the water-soluble polymer to be added to the fracturing fluid is in the form of a water-in-oil inverse emulsion before being formulated, the concentration of the polymer in the emulsion is preferably comprised between 5% and 60% by weight of the total weight of the emulsion, more preferably between 15% and 40%.

[0402] In a preferred embodiment of the application, the water-in-oil inverse emulsion can comprise between 0.01% and 70% (by weight, relative to the total weight of the emulsion) of organic and / or inorganic salts, preferably between 5% and 20%. The salts can be chosen from the non-limiting list comprising sodium chloride, sodium sulfate, sodium bromide, ammonium sulfate, ammonium chloride, lithium chloride, lithium bromide, potassium chloride, potassium bromide, magnesium sulfate, aluminum sulfate and mixtures thereof, among which ammonium chloride and ammonium sulfate are preferred.

[0403] When the water-soluble polymer to be added to the fracturing fluid is in the form of an aqueous multi-phase particle suspension before being formulated, the suspension preferably comprises:

[0404] - between 15% and 60% by weight of at least one water-soluble polymer in the form of solid particles having an average particle size comprised between 5 and 500 pm;

[0405] - between 15% and 45% by weight of at least one alkali metal salt and / or alkaline earth metal salt;

[0406] - at least one thickener of non-water-soluble polymers;

[0407] - at least 10% by weight of water;

[0408] and a Brookfield viscosity at 20°C comprised between 500 and 20,000 cps; and

[0409] The density is comprised between 1.1 and 2 kg.L"1.

[0410] When the water-soluble polymer to be added to the fracturing fluid is in the form of an oily multi-phase particle suspension before being formulated, the suspension preferably comprises:

[0411] - between 15% and 60% by weight of at least one water-soluble polymer in the form of solid particles having an average particle size comprised between 5 and 500 pm;

[0412] - at least one thickening agent of a non-water soluble polymer;

[0413] - at least 10% by weight of an oil;

[0414] and the Brookfield viscosity of the suspension at 20°C is between 500 and 20,000 cps; and

[0415] The density is between 0.6 and 1.4 kg L"1.

[0416] The Brookfield viscosity is measured using a Brookfield viscometer equipped with an LV spindle (spindle speed selectable at 30 rpm), preferably at 20°C. The density is measured at 20°C, 1 atmosphere pressure (i.e. 101,325 Pa).

[0417] Hydraulic fracturing method for unconventional oil and gas reservoirs

[0418] The present invention also relates to a hydraulic fracturing method for unconventional subterranean oil and gas reservoirs, comprising formulating a fracturing fluid as described above and injecting the fracturing fluid into a subterranean reservoir.

[0419] The fractures are distributed and extended along the full length of the production well by means of pressurized injection.

[0420] Optionally, at least one oxidizing compound and / or at least one surface active compound is injected into the reservoir before, during or after the fractures are formed.

[0421] The injection of a surface active compound can eliminate the viscosity created by the polymer by inhibiting the hydrophobic chain-chain interactions, while the injection of an oxidizing compound directly degrades the polymer - both of which can restore the fluid viscosity to near that of water.

[0422] The oxidizing compounds include bleaches (hypochlorite solutions), hydrogen peroxide, ozone, chloramines, persulfates, permanganates and perchlorates.

[0423] The surface active compounds are not limited in their chemical nature and can be anionic, non-ionic, amphoteric, zwitterionic and / or cationic, with the present invention preferably being anionic.

[0424] Preferably, the surface-active compound used is chosen from anionic surfactants and zwitterions thereof, including alkyl sulfate derivatives, alkyl ether sulfates, aryl alkyl sulfates, aryl alkyl ether sulfates, alkyl sulfonates, alkyl ether sulfonates, aryl alkyl sulfonates, aryl alkyl ether sulfonates, alkyl phosphates, alkyl ether phosphates, aryl alkyl phosphates, aryl alkyl ether phosphates, alkyl phosphonates, alkyl ether phosphonates, aryl alkyl phosphonates, aryl alkyl ether phosphonates, alkyl carboxylates, alkyl ether carboxylates, aryl alkyl carboxylates, aryl alkyl ether carboxylates, polyalkyl ethers, aryl alkyl polyethers, and the like.

[0425] An alkyl chain is defined as a branched or linear structure comprising from 6 to 24 carbon atoms, can have multiple units, and optionally comprises one or more heteroatoms (O, N, S). An aryl alkyl chain is defined as a branched or linear structure comprising from 6 to 24 carbon atoms, contains one or more aromatic rings, and can comprise one or more heteroatoms (O, N, S).

[0426] The most commonly used surface-active compounds are of the sulfonate or sulfate type, in the form of alkali metal or ammonium salts, based on cost, stability, and availability considerations.

[0427] Method for reducing the friction of fracturing fluids in hydraulic fracturing operations in unconventional subterranean oil and gas reservoirs

[0428] The present invention also relates to a method for reducing the friction of fracturing fluids in hydraulic fracturing operations in unconventional subterranean oil and gas reservoirs, comprising preparing a fracturing fluid as described above, and injecting the fracturing fluid into a subterranean reservoir.

[0429] The reduction in friction can reduce or eliminate the (pressure) losses caused by friction during the injection of the fracturing fluid.

[0430] Other uses of the polymer

[0431] Another aspect of the present invention relates to the use of the polymer obtained from the ATBS.K crystalline form.

[0432] The present invention also relates to the use of the polymer in the following fields: drilling or cementing operations; profile control and flow diversion; open, closed or semi-closed circuit water treatment; fermentation broth treatment; sludge treatment; construction work; paper or paperboard manufacturing; battery industry; wood treatment; treatment of hydraulic compositions (concrete, cement, mortar and aggregates); cosmetic formulations; detergent formulations; textile manufacturing; geothermal energy development; diaper manufacturing; or agricultural production.

[0433] The present invention also relates to the use of the polymer as a flocculant, binder, absorbent, drainage aid, dewatering agent, conditioning agent, stabilizer, fixative, film-forming agent, sizing agent, water-reducing agent, clay inhibitor or dispersant.

[0434] The application and its advantages will be better understood by way of the following non-limiting description of the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0435] Figure 1 A proton nuclear magnetic resonance spectrum of ATBS acicular crystals obtained according to Example 1 is shown.

[0436] Figure 2 A proton nuclear magnetic resonance spectrum of ATBS.K crystals obtained according to Example 2a is shown.

[0437] Figure 3 An X-ray diffraction pattern of ATBS crystals obtained according to Example 1 is shown.

[0438] Figure 4 An X-ray diffraction pattern of ATBS.K crystals obtained according to Example 2a is shown.

[0439] Figure 5 A Fourier transform infrared spectrum of ATBS crystals obtained in Example 1 is shown.

[0440] Figure 6 A Fourier transform infrared spectrum of ATBS.K crystals obtained in Example 2a is shown.

[0441] Figure 7 A thermal analysis plot of ATBS crystals obtained according to Example 1 is shown.

[0442] Figure 8 A thermal analysis plot of ATBS.K crystals obtained according to Example 2a is shown.

[0443] Figure 9 A particle size distribution of ATBS crystals obtained according to Example 1 is shown.

[0444] Figure 10 A particle size distribution of ATBS.K crystals obtained according to Example 2a is shown.

[0445] Figure 11 An optical microscope view of ATBS crystals obtained according to Example 1 is shown.

[0446] Figure 12a An optical microscope view of ATBS.K crystals obtained according to Example 2a is shown.

[0447] Figure 12b A thermal analysis plot of ATBS.K crystals obtained according to Example 2b is shown.

[0448] Figure 12c A thermal analysis plot of ATBS.K crystals obtained according to Example 2c is shown.

[0449] Figure 12d shows a picture of the ATBS.K product obtained in solution according to Comparative Example 2b (according to US6331647 (Example 27)).

[0450] Figure 12e shows an optical microscope view of ATBS.K crystals obtained according to Comparative Example 2c (according to WO2013079507 (Example 3)).

[0451] Figure 12f shows an optical microscope view of ATBS.K crystals obtained according to Comparative Example 2d.

[0452] Figure 12g shows an optical microscope view of ATBS.K crystals obtained according to Comparative Example 2e.

[0453] Figure 13 shows the corrosion effect of the ATBS used (acid form Example 1) with potassium salt crystals (Example 2a) on a carbon steel plate after 15 days at 50°C.

[0454] Figure 14 shows the curve of the percentage of friction reduction of the polymer as a function of time.

[0455] Figure 15 shows the curve of the percentage of friction reduction of the homopolymer as a function of time.

[0456] Figure 16 shows the curve of the percentage of friction reduction of the terpolymer as a function of time.

[0457] Figure 17 shows the curve of the percentage of friction reduction of the post-hydrolyzed polymer as a function of time.

[0458] Figure 18 shows the effect of the ATBS form on the viscosity loss of the homopolymer P3 (the present invention) and P'3 (ATBS acid form) solutions when they are in contact with different amounts of iron (II) contaminant.

[0459] Figure 19 shows the effect of the ATBS form on the viscosity loss of the polymers P3 (the present invention) and P'3 (ATBS acid form) when they are aged at 90°C.

[0460] Figure 20 shows the effect of the ATBS form on the viscosity loss of the homopolymer P5 (the present invention) and P'5 (ATBS acid form) solutions when they are in contact with different amounts of iron (II) contaminant. Example

[0461] Example 1 : Synthesis of 2-acrylamido-2-methylpropanesulfonic acid (ATBS) (AH )

[0462] To a 2000 ml stirred double-jacketed reactor was added 1522 g of acrylonitrile with a water content of 0.4 wt% and 180 g of oleum with a titration of 104% H2SO4(18% oleum). The mixture was stirred for 1 hour and the temperature of the sulfonation mixture was maintained at -20°C by the reactor double-jacket cooling system.

[0463] To the above sulfonation mixture was added 97 g of isobutene at a rate of 1.6 g per minute.

[0464] The temperature of the mixture was controlled at 45°C during the addition of isobutene. ATBS particles precipitated from the mixture with a solid content of about 20 wt%. The reaction mixture was filtered through a Buchner funnel and dried under vacuum at 50°C. The resulting solid was 2-acrylamido-2-methylpropane sulfonic acid (ATBS A H ) in the form of a white fine powder.

[0465] Optical microscopy observations Figure 11 showed that ATBS A H crystals presented a needle-like morphology.

[0466] Example 2a: Preparation of a crystalline form of the potassium salt of 2-acrylamido-2-methylpropane sulfonic acid (ATBS.K A K 2a) (of the invention)

[0467] To a 1000 ml stirred double-jacketed reactor was added 477 g of a 28 wt% aqueous solution of potassium hydroxide, then to this mixture was added 452 g of ATBS A H .

[0468] The mixture was stirred at 10°C for 30 minutes to form an aqueous solution SA2.

[0469] The aqueous solution SA2 was heated to 40°C under vacuum at 50 mbar for 20 minutes, then kept at 50 mbar for 30 minutes and then cooled to 10°C. The time to cool from 40°C to 10°C was 6 hours to obtain a suspension of ATBS.K crystals S1. The suspension S1 was filtered through a Robatel vertical centrifuge to obtain a solid product with composition C1 containing 80 wt% of ATBS.K A K 2a crystals.

[0470] Optical microscopy observations Figure 12a showed that AK2a crystals presented a columnar and plate-like morphology.

[0471] Example 2b: Preparation of a crystalline form of the potassium salt of ATBS (ATBS.K A K 2b)

[0472] The remaining steps were identical to Example 2a, except that the SA2 solution was distilled under 700 mbar, to produce ATBS.K A K 2b crystals.

[0473] Optical microscope observation (Fig. 2) showed that the crystals obtained under these conditions were identical to the ATBS.K A Figure 12b 2a crystals. K 2b crystals were identical to the ATBS.K A K 2a crystals.

[0474] Example 2c: Preparation of a crystalline form of ATBS potassium salt (ATBS.K A K 2c)

[0475] The remaining steps were identical to Example 2a, except that the cooling time was reduced to 3 hours and 45 minutes, to produce ATBS.K A K 2c crystals.

[0476] Optical microscope observation (Fig. 2) showed that the crystals obtained under these conditions were identical to the ATBS.K A Figure 12c 2a crystals. K 2a crystals.

[0477] Comparative Example 2a: Preparation of ATBS.K crystals under atmospheric pressure (1 bar) (CE-A K 2a) (not obtained)

[0478] The remaining steps were identical to Example 2a, except that the SA2 solution was distilled under atmospheric pressure.

[0479] After the cooling step, the aqueous solution SA2 did not form a suspension S1 and the ATBS potassium salt crystals could not be isolated by filtration or centrifugation.

[0480] Comparative Example 2b: Preparation of ATBS potassium salt crystals (CE-A K 2b) (not obtained)

[0481] The reaction was performed according to the conditions described in Example 27 of US Patent 6,331,647.

[0482] To a 5000 ml stirred double-jacketed reactor containing 400 g of water, 124 g of potassium hydroxide and 0.13 g of p-phenylenediamine monomethyl ether were added, stirring until the potassium hydroxide was completely dissolved.

[0483] To the above mixture, 632 g of ATBS A H were added, stirring at 10°C for 30 minutes to form an aqueous solution of ATBS.K.

[0484] The resulting aqueous solution was transferred to a 3000 ml reactor equipped with a distillation apparatus and an air sparge tube, the contents were heated and stirred while sparging air under the liquid surface at a rate of 0.5 cubic feet per hour. The contents were heated to 50°C under vacuum at 933 mbar (~ 700 mm Hg). As the water evaporated, a honey-like yellow product was obtained. The product was transferred to a Robatel vertical centrifuge for processing, but no solids were recovered.

[0485] Optical microscopy observation Figure 12d ) was not possible as no solid product was obtained.

[0486] Comparative Example 2c: Preparation of ATBS Potassium salt crystals (CE-A K 2c) (not obtained)

[0487] The reaction was performed according to the conditions described in International application WO2013079507 example 3.

[0488] A 100 g solution of ATBS.K (concentration 16.77 wt%) was prepared according to WO2013079507 example 1.

[0489] At room temperature under reduced pressure, 50 g of solvent was removed from the ATBS.K solution while sparging air into the solution. The solid that formed was filtered, washed with acrylonitrile / methanol mixed solvent and dried at 50°C overnight.

[0490] Optical microscopy observation Figure 12e ) of the dried ATBS.K CE-A K 2c solid did not match the morphology of the ATBS.K crystals described in the present application.

[0491] Comparative Example 2d: Preparation of ATBS.K CE-A K 2d (not in the present application)

[0492] The procedure was identical to example 2a except that the SA2 solution was distilled at 720 mbar.

[0493] A solid product with composition CI was obtained, containing 80 wt% of ATBS.K CE-A K 2d crystals.

[0494] Optical microscopy observation Figure 12f ) of the ATBS.K CE-A K 2d crystals did not match the morphology of the ATBS.K crystals described in the present application.

[0495] Comparative Example 2e: Preparation of ATBS.K CE-A K 2e (not in the present application)

[0496] The remaining steps were identical to Example 2a, except that the cooling time was reduced to 3 hours and 20 minutes.

[0497] A solid product with a composition of C1 was obtained, containing 80 wt% of ATBS.K CE-A K 2e crystals.

[0498] Optical microscopy observation Figure 12g ) showed that the ATBS.K CE-A K 2e crystals did not match the ATBS.K crystal morphology described in the present application.

[0499] Example 3: ATBS A H and ATBS.K A K 2a products. H and ATBS.K A K 2a products.

[0500] The samples were dissolved in heavy water (D2O) and analyzed using a Bruker 400 MHz model nuclear magnetic resonance spectrometer equipped with a 5 millimeter BBO BB- 1 H probe.

[0501] Both proton spectra Figure 1 and Figure 2 presented similar features, with peak assignments consistent with the molecular structure of ATBS and its potassium salt.

[0502] Example 4: X-ray diffraction analysis of ATBS A H and ATBS.K A K 2a products.

[0503] ATBS A H and ATBS.K A K 2a crystals were previously ground into powder and analyzed by X-ray diffraction in the angular range of 10° to 90°. A Rigaku MiniFlex II diffractometer equipped with a copper target source was used.

[0504] The X-ray diffraction pattern of ATBS.K A K 2a crystals Figure 4 presented the following characteristic peaks:

[0505] 13.1°; 14.4°; 16.3°; 19.8°; 23.5°; 24.3°; 26.9°; 27.6°; 29.3°; 30.6°; 31.6°; 34.3°; 36.1°; 41.7°; 44.6°; 46.7° 2Q (± 0.1°).

[0506] ATBS A H X-ray diffraction pattern ( Figure 3 (The same characteristic peaks were not observed.)

[0507] Example 5: ATBS A H with ATBS.KA K Infrared spectroscopy measurement of 2a

[0508] A Perkin Elmer Spectrum 100 Fourier transform infrared spectrometer, equipped with a single-reflection ATR polarization accessory, was used, with a measurement accuracy of 8 cm⁻¹. -1 .

[0509] ATBS A H andATBS.KA K 2a is sieved to 100 microns, and the particles on the sieve are dried and then treated in an oven at 60°C for at least 4 hours.

[0510] Several hundred milligrams of solid sample were placed on a diamond wafer in the ATR accessory and measured by manually applying pressure.

[0511] The following characteristic peaks ( Figure 6 ) is ATBS potassium salt A K Typical spectral bands of the 2a crystal form:

[0512] 3293cm -1 3075cm -1 3000cm -1 2979cm -1 1655cm -1 1625cm - 1,1550cm -1 1405cm -1 1209cm -1 1190cm -1 1162cm -1 1048cm -1 979cm -1 824cm -1 803cm -1 756cm -1 633cm -1 523cm -1 .

[0513] ATBS A H infrared spectrum ( Figure 5 (The same characteristic peaks were not observed.)

[0514] Example 6: ATBS A obtained from Examples 1 and 2aH ATBS.K A K 2a Differential scanning calorimetry (DSC) analysis of the product

[0515] The test was performed using a Mettler DSC 3 analyzer under nitrogen flow protection at a temperature increase rate of 10°C / min. The starting temperature was 30°C and the end temperature was 350°C.

[0516] ATBS A H Thermogram of the crystals of 2a Figure 7 showed a thermal effect at 195.15°C, temperature generally considered as the melting / degradation point of 2-acrylamido-2-methylpropane sulfonic acid.

[0517] ATBS.K A K Thermogram of the crystals of 2a Figure 8 showed two thermal phenomena at 79.4°C and 207°C.

[0518] For comparison, the thermogram of the crystals of Example 1 showed only one degradation peak at 195.15°C, followed by two exothermic degradation phenomena at 212.8°C and 288.4°C Figure 7 .

[0519] Example 7: ATBS A obtained from Examples 1 and 2a H ATBS.K A K 2a Measurement of the minimum ignition energy (MIE) of the product

[0520] The minimum ignition energy was measured according to the NF EN 13821 standard.

[0521] A vertical Hartmann tube explosimeter was used, equipped with a mushroom-type dust dispersion system.

[0522] The total inductance was less than 25 microhenries, the discharge voltage was between 5 kV and 15 kV, brass electrodes were used and the electrode spacing was not less than 6 mm.

[0523] The tests carried out with different energies and dispersion masses (results summarized in Tables 1 and 2) showed that the ATBS.K A K 2a crystalline form compared to the acicular ATBS A obtained from Example 1 H has a significantly reduced risk of explosion.

[0524]

[0525] Table 1: ATBS A H MIE value determination for solids

[0526]

[0527]

[0528] Table 2: ATBS.K A K 2a Determination of solid MIE values

[0529] Example 8: Evaluation of ATBS A H vs. ATBS.K A K 2a Particle size measurement of product

[0530] Analysis of ATBS A H vs. ATBS.K A K 2a Particle size distribution of crystals.

[0531] The laser diffraction equipment used was a Cilas 1190.

[0532] ATBS A H d 50 values of about 40 microns, with 90% of the particles having a size less than 100 microns Figure 9 .

[0533] ATBS.K A K d 50 values of about 600 microns, with 90% of the particles having a size less than 1500 microns Figure 10 . The content of particles smaller than 325 microns in this crystal was less than 10%.

[0534] Example 9: Evaluation of the corrosion of carbon steel by different forms of ATBS

[0535] Twenty grams of ATBS A H, ATBS.K A K 2a and ATBS.K CE-A K 2c to 2e were placed on the surface of carbon steel panels of dimensions 20 x 50 mm 2 . The coated panels were placed in an oven at 50°C for two weeks, while a blank control panel, not coated, was placed in the same conditions of temperature.

[0536] The photographs of the panels in this state Figure 13 show that the surface of the panel in contact with ATBS A K 2a crystals was more corroded than the surface of the panel in contact with ATBS.K A H This observation was confirmed by weighing the panels before and after contact.

[0537] In addition, crystals of ATBS potassium salt CE-A K 2c to 2e were tested, the results of which are shown in Table 3.

[0538]

[0539]

[0540] Table 3: Corrosivity of ATBS in different forms on carbon steel

[0541] Example 10a: ATBS.K A K Preparation of 2a solution

[0542] 1000 grams of ATBS.K A K 2a crystals were added to a 2000 ml jacketed reaction kettle equipped with a condenser, pH meter and stirrer along with 1000 grams of water. The pH of the mixed solution was greater than 12.

[0543] The resulting mixture was a 50 wt% aqueous solution of ATBS.K A.

[0544] Example 10b: ATBS.K CE-A K Preparation of 2c solution

[0545] ATBS.K CE-A K 2c crystals were added to a 2000 ml jacketed reaction kettle equipped with a condenser, pH meter and stirrer along with 1000 grams of water. The pH of the mixed solution was greater than 12.

[0546] Example 10c: ATBS.K CE-A K Preparation of 2d solution

[0547] ATBS.K CE-A K 2d crystals were added to a 2000 ml jacketed reaction kettle equipped with a condenser, pH meter and stirrer along with 1000 grams of water. The pH of the mixed solution was greater than 12.

[0548] Example 10d: ATBS.K CE-A K Preparation of 2e solution

[0549] ATBS.K CE-A K 2e crystals were added to a 2000 ml jacketed reaction kettle equipped with a condenser, pH meter and stirrer along with 1000 grams of water. The pH of the mixed solution was greater than 12.

[0550] Example 11: ATBS.K from acid form A H Preparation of ATBS.K solution

[0551] 800 grams of ATBS A H was added to a 2000 ml jacketed reaction kettle equipped with a condenser, pH meter and stirrer along with 650 grams of water. The pH of the mixed solution was less than 1.

[0552] A 50 wt% aqueous solution of potassium hydroxide was prepared in a dropping funnel and the base was added to the reaction mixture over a period of 120 minutes, with temperature control at below 30°C.

[0553] The final pH of the solution was between 8-10.

[0554] A total of 451 g of a 50 wt% aqueous potassium hydroxide solution was added.

[0555] The resulting mixture was an aqueous solution of ATBS potassium salt at a concentration of 50 wt%.

[0556] Example 12: Effect of ATBS morphology and structure on storage stability

[0557] 500 g of a 50% concentration ATBS.K aqueous solution prepared according to Examples 10a-d and 11 was stored for 12 months, and its long-term stability was compared by monitoring the generation of ATBS.K homopolymer.

[0558] At the same time, the stability of ATBS in different forms (acid form A H or potassium salt A K 2a) was also evaluated for the same period.

[0559] In this case, every three months, the stored ATBS products A H , A K 2a and CE-A K 2c to 2e were used to freshly prepare 500 g of ATBS.K solution according to the preparation process described in Example 10a or 11.

[0560] At the same time, the stability of the solid products was evaluated by monitoring the amount of ATBS.K homopolymer generated after this period.

[0561] Liquid space exclusion chromatography analysis was performed using an Agilent 1260 chromatograph with Aquagel-OH 20, 30, 40 and 50 series chromatographic columns, which can detect anionic polymers with a molecular weight of up to 600,000 g / mol (polyethylene glycol equivalent).

[0562] The ATBS.K solution was diluted to 2000 ppm (aqueous solution weight concentration) before injection. The characteristic peaks of the polymer in the 250 nm ultraviolet signal region after the column were integrated and analyzed, and the specific data are shown in Tables 4 and 5. The larger the signal peak area, the higher the polymer content, and the poorer the stability of the product over time.

[0563]

[0564] Table 4: Storage stability study of ATBS and ATBS potassium salt solutions

[0565]

[0566]

[0567] Table 5: Storage stability study of ATBS and ATBS potassium salt in solid form

[0568] The above results show that the ATBS.K crystal form of the present application exhibits improved storage stability, whether stored as a solid or in solution.

[0569] Example 13: Preparation of acrylamide (AM) / ATBS (75 / 25 mol%) polymer

[0570] Example 13a: Polymers P1 to P3-A of the present application K Preparation of 2a

[0571] Into a 2000 ml beaker was added 628.3 g of deionized water, 500 g of a 50 wt% acrylamide solution, 16.2 g of urea and 288.7 g of ATBS.K A K 2a crystals.

[0572] The resulting solution was cooled to 0-5°C and transferred to an adiabatic polymerization reactor and sparged with nitrogen for 30 minutes to remove dissolved oxygen.

[0573] Subsequently, to the reactor was added:

[0574] - 0.75 g of 2,2'-azobisisobutyronitrile

[0575] - 1.5 ml of an aqueous solution of 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (5 g / liter)

[0576] - 1.5 ml of an aqueous solution of sodium hypophosphite (3 g / liter)

[0577] - 2.25 ml of an aqueous solution of tert-butyl hydroperoxide (1 g / liter)

[0578] - 2.25 ml of an aqueous solution of ferrous ammonium sulfate (Mohr's salt) (1 g / liter)

[0579] After a few minutes, the nitrogen inlet was closed and the reactor was sealed and the polymerization was continued for 1-5 hours until a temperature peak was reached and the resulting rubbery gel was cut into 1-6 mm particles.

[0580] After drying and grinding, a powdered polymer P1-A was obtained K 2a.

[0581] By varying the amount of sodium hypophosphite, polymer P2-A was obtained in the same way K 2a and P3-A K 2a:

[0582] P2-A K 2a: 1.2 ml of a 3 g / liter sodium hypophosphite solution was added

[0583] P3-A K 2a: 1.5 ml of a 1 g / liter sodium hypophosphite solution was added

[0584] Example 13b: Preparation of comparative polymer ATBS / AM (75 / 25)

[0585] Using 243 grams of ATBS A H and 131.7 grams of 50 wt% aqueous potassium hydroxide, reference polymers P1 to P3-A K Polymers P'1-A were prepared according to the synthesis scheme of 2a H , P'2-A H and P'3-A H .

[0586] Using ATBS CE-A K 2c crystals, reference P1 to P3-A K Polymers P'1-CE A were prepared according to the synthesis scheme of 2a K 2c, P'2-CE A K 2c and P'3-CE A K 2c.

[0587] Using ATBS CE-A K 2d crystals, reference P1 to P3-A K Polymers P'1-CE A were prepared according to the synthesis scheme of 2a K 2d, P'2-CE A K 2d and P'3-CE A K 2d.

[0588] Using ATBS CE-A K 2e crystals, reference P1 to P3-A K Polymers P'1-CE A were prepared according to the synthesis scheme of 2a K 2e, P'2-CE A K 2e and P'3-CE A K 2e.

[0589] Example 14: Preparation of ATBS homopolymer

[0590] Reference Example 13a P1-A K 2a, the preparation scheme of 2a was followed by adjusting the amounts of monomers and auxiliaries to reach the target molar composition of 100 mol% ATBS, to prepare polymers P4-A K 2a and P5-A K 2a (P4-A K 2a: 20 ml of 1 g / l sodium secondary phosphate solution were added; P5-A K 2a: 3 ml of 1 g / l sodium secondary phosphate solution were added).

[0591] Using 352.1 grams and 243 grams of ATBS A Hand 190.8 grams of a 50 wt% aqueous potassium hydroxide solution, according to P1 to P3-A K 2a Synthesis scheme to make polymer P'4-A H and P'5-A H .

[0592] Using ATBS CE-A K 2c Crystals, according to P1 to P3-A K 2a Synthesis scheme to make polymer P'4-CEA K 2c and P'5-CEA K 2c.

[0593] Using ATBS CE-A K 2d Crystals, according to P1 to P3-A K 2a Synthesis scheme to make polymer P'4-CEA K 2d and P'5-CEA K 2d.

[0594] Using ATBS CE-A K 2e Crystals, according to P1 to P3-A K 2a Synthesis scheme to make polymer P'4-CEA K 2e and P'5-CEA K 2e.

[0595] Example 15: Preparation of AM / ATBS / Acrylic Acid (AA) (71 / 9 / 20 mol%) polymer, according to the preparation scheme for P1 in Example 13a, by adjusting the amounts of monomers and adjuvants to achieve the target molar composition of AM / ATBS / AA (71 / 9 / 20), to make polymer P6-A K 2a.

[0596] Polymer P'6-A H Preparation: Using 105.2 grams of ATBS A H and 181.4 grams of a 50 wt% aqueous potassium hydroxide solution, according to P1-A K 2a Synthesis scheme to make polymer P'6-A.

[0597] Polymer P'6-CEA K 2c Preparation: Using ATBS CE-A K 2c Crystals, according to P1 to P3-A K 2a Synthesis scheme to make polymer P'6-CEA.

[0598] Polymer P'6-CEA K 2d Preparation: Using ATBS CE-A K 2d Crystals, according to P1 to P3-A K 2a Synthesis scheme to make polymer P'6-CEA.

[0599] Polymer P'6-CEA K Preparation of 2e: Using ATBS CE-A K 2e crystals, reference P1 to P3-A K 2a synthesis scheme.

[0600] Example 16: Preparation of post hydrolyzed polymer of AM / ATBS (90 / 10 mol%)

[0601] Polymer P7-A was prepared by adjusting the amounts of monomers and coagents to achieve the target molar composition of AM / ATBS (90 / 10) using the preparation scheme for P1 in reference example 13a. K 2a.

[0602] Take 500.0 grams of pre-chopped gel and mix with 22.5 grams of 50 wt% sodium hydroxide solution and heat at 90°C for 90 minutes.

[0603] After drying and milling, a powdered polymer P7-A was obtained K 2a.

[0604] Preparation of Polymer P'7-AH: Using 93.1 grams of ATBS A H and 50.1 grams of 50 wt% aqueous potassium hydroxide solution, reference P7-A K 2a preparation scheme.

[0605] Polymer P'7-CEA K Preparation of 2c: Using ATBS CE-A K 2c crystals, reference P7-A K 2a synthesis scheme.

[0606] Polymer P'7-CEA K Preparation of 2d: Using ATBS CE-A K 2d crystals, reference P7-A K 2a synthesis scheme.

[0607] Polymer P'7-CEA K Preparation of 2e: Using ATBS CE-A K 2e crystals, reference P7-A K 2a synthesis scheme.

[0608] Example 17: Viscosity determination of AM / ATBS (75 / 25 mol%) polymer solution

[0609] The viscosity of the polymer prepared in Example 13 was determined using a Brookfield LVT viscometer equipped with a UL adapter at 60 rpm in 0.5 M aqueous sodium chloride at 25 °C.

[0610] Polymer solution preparation method:

[0611] 500 mg of dry polymer was dissolved in a beaker containing 290 mL of deionized water with stirring at 500 rpm.

[0612] 29.25 g of sodium chloride was added to the prepared solution.

[0613] Stirring was continued at 700 rpm for 10 minutes to ensure complete dissolution of the salt.

[0614] The solution was filtered using a 200 μιη filter screen.

[0615] 16 mL of the prepared solution was removed into a cylindrical test tube for viscosity determination. The results of the polymer solution viscosity test are shown in Table 6.

[0616]

[0617]

[0618] Table 6: ATBS polymer solution viscosity (Note: Inv = Inventive Example, CE = Comparative Example)

[0619] The polymer prepared using the new ATBS.K crystal form had a significantly higher solution viscosity than the polymer prepared using the conventional ATBS.K or other potassium salt crystal forms.

[0620] Example 18: Preparation of ATBS polymer fracturing fluid

[0621] The polymers prepared in Examples 13 to 16 were dissolved in a brine base fluid (containing 85 g of sodium chloride and 33.1 g of calcium chloride dihydrate per liter) at a concentration of 10,000 ppm by weight, and the solution was prepared under stirring.

[0622] The resulting salt polymer solution was injected into the brine base fluid at a concentration of 0.05 pptg (thousand gallons fraction; 1 gallon = 3.78541 liters) and circulated for subsequent flow channel testing.

[0623] Example 19: ATBS polymer flow channel friction reduction testing

[0624] To evaluate the friction reduction performance of each polymer, 20 liters of brine base fluid (having the same formulation as in Example 18) was injected into the flow channel tank.

[0625] The brine base fluid was circulated at a flow rate of 24 gallons per minute, and then the polymer was added to the circulating system at a concentration of 0.5 pptg.

[0626] The percent friction reduction is calculated by measuring the pressure change in the flow channel.

[0627] Figures 14 to 17 The friction reduction rate of the polymers P1, P4, P6, P7-A of the present application K 2a and comparative polymers P'1, P'4, P'6, P'7-A H as a function of time.

[0628] The graph shows that the injection fluid prepared by the present application has more excellent friction reduction performance. When the polymer contains the ATBS.K crystal form, the friction reduction effect is significantly improved.

[0629] Example 20: AM / ATBS (75 / 25 mol) polymer solution filtration ratio (FR) determination

[0630] The polymer described in Example 13 was subjected to filtration test.

[0631] The polymer solution was prepared into 1000 ppm effective concentration in brine containing 30,000 ppm NaCl and 3,000 ppm CaCl2·2H2O (weight ppm). The filtration ratio (FR) was determined using a filter with a pore size of 1.2 μm, which can simulate the characteristics of low permeability reservoirs. The test results are shown in Table 7.

[0632]

[0633]

[0634] Table 7: AM / ATBS copolymer filtration ratio determination results

[0635] As can be seen from Table 7: under the condition of similar molecular weight, the filtration ratio (FR) of the polymer (P1, P2 and P3-A K 2a) prepared by the ATBS.K crystal form of the present application is always lower than that of the polymer prepared by the amorphous ATBS.K or other crystal form ATBS.K. With the increase of the molecular weight of the polymer, this difference becomes more and more significant.

[0636] Example 21: Equivalent molecular weight AM / ATBS (75 / 25) polymer solution chemical degradation resistance test

[0637] Under aerobic conditions, the polymer P3-A K2a Comparison of the chemical degradation resistance of polymer P'3 series in saline media with different ferrous iron concentrations (2, 5, 10 and 20 ppm) (formulation: water + 37,000 ppm NaCl + 5,000 ppm Na2SO4 + 200 ppm NaHCO3, ppm by weight). Figure 18 The test results are shown after the P3-AK2a and P'3-AH polymer solutions were in contact with iron contaminants for 24 hours.

[0638] See Table 8 for detailed chemical degradation test data for all P3 series polymers.

[0639]

[0640]

[0641] Table 8: Inventive Polymer P3-A K 2a and comparative polymer P'3-A H P'3-CEA K Determination of resistance to chemical degradation from 2c to 2e

[0642] like Figure 18 As shown in Table 8: Under all ferrous iron concentration conditions, polymer P3-A K The viscosity loss rate of 2a was lower than that of the equivalent comparative polymer P'3-A. H and P'3-CEA K 2c to 2e.

[0643] Example 22: Test on the thermal degradation resistance of AM / ATBS (75 / 25) polymer solution with equivalent molecular weight

[0644] Under anaerobic conditions, polymer P3-A in Example 13 was tested. K The thermal degradation resistance of polymer 2a and the control polymer P'3 series in a brine medium (containing 30,000 ppm NaCl and 3,000 ppm CaCl2·2H2O, ppm by weight) at an effective concentration of 2000 ppm was compared. The polymer solution was aged at 90°C for 6 months.

[0645] Figure 19 P3-A was demonstrated K The viscosity loss results of 2a and P'3-AH polymer solutions are shown in Table 9. Test data for all P3 series polymers are detailed in Table 9.

[0646] Polymer Type of ATBS used Rate of viscosity loss (%) [P3-A K 2a(inv) Crystals of ATBS.K A K 2a]]> 34.5 P'3-A H (CE)] ATBS A H ]]> 47 P'3-CEA K 2c (CE) ATBS.K CE-A K 2c]]> 46.5 P'3-CEA K 2d (CE) ATBS.K CE-A K 2d]]> 49 P'3-CEA K 2e (CE) ATBS.K CE-A K 2e]]> 50

[0647] Table 9: Inventive Polymer P3-A K 2a and comparative polymers P'3-AH and P'3-CEA K2c to 2e Anti-thermal degradation performance determination

[0648] Figure 19 and Table 9 show that the polymer P3-A K 2a has a lower viscosity loss rate than the equivalent comparative polymer P'3-A H and P'3-CEA K 2c to 2e.

[0649] Example 23: Filtration ratio determination of ATBS homopolymer solution

[0650] The filtration test was performed on the polymer P4-P5 prepared in Example 14 according to the method described in Example 20, and the results are shown in Table 10.

[0651]

[0652]

[0653] Table 10: Filtration ratio determination results of ATBS homopolymer

[0654] As can be seen from Table 10, under the condition of similar molecular weight, the polymer (P4 / 5-A K 2a) prepared by using the ATBS.K crystal form of the present application has a filtration ratio (FR) that is always lower than the equivalent comparative polymer P'4 / 5-A H and P'4 / 5-CEA K 2c to 2e. With the increase of the molecular weight of the polymer, this difference becomes more and more significant.

[0655] Example 24: Anti-chemical degradation performance test of AM / ATBS / AA (71 / 9 / 20) polymer solution

[0656] The anti-chemical degradation test was performed on the polymer P6 and P'6 series prepared in Example 15 according to the method described in Example 21. Figure 20 The test results of P6-A K 2a and P'6-AH polymer solution after being in contact with iron contaminants for 24 hours are shown.

[0657] The anti-chemical degradation test data of all P6 series polymers are shown in Table 11.

[0658]

[0659]

[0660] Table 11: Anti-chemical degradation performance test results of the inventive polymer P6-A K 2a and the comparative polymer P'6-A H , P'6-CEA K 2c to 2e

[0661] Figure 20 and Table 11 show that at all divalent iron concentrations, the polymer P6-A K 2a has a lower viscosity loss rate than the equivalent comparative polymer P'6-A H and P'6-CEA K 2c to 2e.

[0662] Example 25: Post-hydrolysis AM / ATBS (90 / 10 mol%) polymer solution filtration ratio determination

[0663] The polymer prepared in Example 16 was tested for filtration according to the test method described in Example 20, and the results are shown in Table 12.

[0664]

[0665] Table 12: Post-hydrolysis AM / ATBS (90 / 10 mol%) polymer filtration ratio determination results

[0666] The data show that the high molecular weight polymer P7-A K 2a of the application has a lower filtration ratio (FR) than the comparative polymers P'7-AH and P'7-CEA K 2c to 2e.

[0667] Example 26: Coal mine wastewater treatment application

[0668] The polymers P1-A K 2a, P'1-A H and P'1-CEA K 2c to 2e were dissolved in tap water to prepare aqueous solutions at a concentration of 0.4 wt% (based on the total weight of the solution). Mechanical stirring was performed at a speed of 500 rpm until complete dissolution, obtaining clear and homogeneous solutions.

[0669] A series of flocculation tests were performed on a coal mine wastewater having a solid content of 18.2 wt%:

[0670] A sample of 200 grams of wastewater was added with the polymer solution at a dosage of 280 grams of polymer per ton of dry matter, and the mixture was manually mixed until the optimal flocculation effect and water release were observed.

[0671] The results are expressed in terms of net water release (NWR), which is equal to the total amount of water recovered after 1 hour of flocculation test, minus the amount of water introduced during the incorporation of the polymer solution. The NWR value was calculated again after 24 hours, which effectively indicates the maximum water release capacity. The test results are summarized in Table 13.

[0672]

[0673] Table 13: The polymer P1-A of the application was used K 2a and comparative polymer P'1-AH, P'1-CEA K 2c to 2e of the net water release rate (NWR) test results

[0674] The experimental results show that the polymer prepared by using the ATBS.K crystal form of the application can significantly improve the flocculation treatment effect of coal mine wastewater.

[0675] Example 27: Bayer red mud treatment application

[0676] According to the scheme described in Example 26, a series of tests were carried out on the Bayer red mud with a solid content of 22.8wt%, and the polymer dosage was 740 grams per ton of red mud dry matter. The test results are shown in Table 14.

[0677]

[0678] Table 13: The polymer P1-A of the application was used K 2a and comparative polymer P'1-AH, P'1-CEA K 2c to 2e of the net water release rate (NWR) test results

[0679] The experimental results show that the polymer prepared by using the ATBS.K crystal form of the application can significantly improve the flocculation treatment effect of coal mine wastewater.

Claims

1. A crystalline form of potassium 2-acrylamido-2-methylpropane sulfonate (ATBS.K form), having an X-ray powder diffraction pattern with characteristic peaks at 13.1°, 14.4°, 16.3°, 19.8°, 23.5°, 24.3°, 26.9°, 27.6°, 29.3°, 30.6°, 31.6°, 34.3°, 36.1°, 41.7°, 44.6°, 46.7° 2Q (±0.1°).

2. The potassium 2-acrylamide-2-methylpropanesulfonate crystal form as described in claim 1, characterized in that, its Fourier transform infrared spectrum has characteristic peaks at 3293 cm -1 , 3075 cm -1 , 3000 cm -1 , 2979 cm -1 , 1655 cm -1 , 1625 cm -1 , 1550 cm -1 , 1405 cm -1 , 1209 cm -1 , 1190 cm -1 , 1162 cm -1 , 1048 cm -1 , 979 cm -1 , 824 cm -1 , 803 cm -1 , 756 cm -1 , 633 cm -1 , 523 cm -1 (±8 cm -1 ).

3. The potassium 2-acrylamide-2-methylpropanesulfonate crystal form as described in claim 1 or 2, characterized in that, Its minimum ignition energy is greater than 500 mJ.

4. The potassium 2-acrylamido-2-methylpropanesulfonate salt crystalline form of any one of claims 1-3, characterized by, It exhibits two thermal phenomena at 79.4°C and 207°C (±10°C) when tested by differential scanning calorimetry.

5. A process for the preparation of a crystalline form of potassium 2-acrylamido-2-methylpropane sulfonate according to any one of claims 1 to 4, comprising at least the following successive steps: 1) mixing 2-acrylamido-2-methylpropane sulfonic acid with an aqueous solution SA1 and at least one potassium salt base, to form an aqueous solution or an aqueous suspension SA2; 2) distilling the aqueous solution or the aqueous suspension SA2 under a pressure of 700 mbar or less, to form a suspension S1 ; 3) subjecting the suspension S1 to a solid-liquid separation, the crystals in the suspension S1 obtained at the end of step 2) being separated to form a composition C1.

6. The method of claim 5, wherein, The content of ATBS.K in the aqueous solution or the aqueous suspension SA2 is between 10 and 90% by weight relative to the total weight of the solution.

7. The method of claim 5 or 6, wherein, The aqueous solution or the aqueous suspension SA2 is heated in step 2), preferably at a temperature ranging from 5°C to 95°C.

8. The method according to any one of claims 5 to 7, wherein, Step 2) also comprises a cooling step, preferably at a temperature ranging from 5°C to 95°C.

9. The method according to any one of claims 5 to 8, wherein, The cooling rate of the cooling step is between 0.1 and 8°C / hour.

10. The method according to any one of claims 5 to 9, wherein, The content of the ATBS.K form in the suspension S1 is between 30 and 90% by weight relative to the total weight of the suspension.

11. The method according to any one of claims 5 to 10, wherein, The potassium salt is chosen from potassium hydroxide, potassium carbonate, potassium bicarbonate or a mixture thereof.

12. A polymer made at least in part from the ATBS.K form, having an X-ray powder diffraction pattern with characteristic peaks at 13.1°, 14.4°, 16.3°, 19.8°, 23.5°, 24.3°, 26.9°, 27.6°, 29.3°, 30.6°, 31.6°, 34.3°, 36.1°, 41.7°, 44.6°, 46.7° 2Q (±0.1°).

13. A process for treating a suspension of solid particles in water, comprising contacting the suspension with at least one water-soluble polymer made at least in part from the ATBS.K form, having an X-ray powder diffraction pattern with characteristic peaks at 13.1°, 14.4°, 16.3°, 19.8°, 23.5°, 24.3°, 26.9°, 27.6°, 29.3°, 30.6°, 31.6°, 34.3°, 36.1°, 41.7°, 44.6°, 46.7° 2Q (±0.1°).

14. A method for flocculating a water suspension of solid particles, comprising contacting said suspension with at least one water-soluble polymer, which is at least partially made from the ATBS.K crystal form, and which has a X-ray powder diffraction pattern with characteristic peaks at 13.1°, 14.4°, 16.3°, 19.8°, 23.5°, 24.3°, 26.9°, 27.6°, 29.3°, 30.6°, 31.6°, 34.3°, 36.1°, 41.7°, 44.6°, 46.7° 2Θ (±0.1°).

15. A method for enhanced hydrocarbon recovery, comprising the steps of: a) preparing an injection fluid comprising at least one water-soluble polymer of 2-acrylamido-2-methylpropane sulfonic acid and water or brine; said 2-acrylamido-2-methylpropane sulfonic acid being at least partially in the ATBS.K crystal form prior to polymerization, and which has a X-ray powder diffraction pattern with characteristic peaks at 13.1°, 14.4°, 16.3°, 19.8°, 23.5°, 24.3°, 26.9°, 27.6°, 29.3°, 30.6°, 31.6°, 34.3°, 36.1°, 41.7°, 44.6°, 46.7° 2Θ (±0.1°); b) injecting the injection fluid into a subterranean formation; c) displacing said subterranean formation with the injection fluid; d) recovering a water-containing hydrocarbon mixture.

16. A fracturing fluid comprising at least one aqueous phase, proppants and at least one water-soluble polymer, which is at least partially made from the ATBS.K crystal form, and which has a X-ray powder diffraction pattern with characteristic peaks at 13.1°, 14.4°, 16.3°, 19.8°, 23.5°, 24.3°, 26.9°, 27.6°, 29.3°, 30.6°, 31.6°, 34.3°, 36.1°, 41.7°, 44.6°, 46.7° 2Θ (±0.1°).

17. A method for preparing a fracturing fluid as claimed in claim 14, by adding at least one water-soluble polymer, which is at least partially made from the ATBS.K crystal form, and which is in one of the following forms prior to the water-soluble polymer forming the fracturing fluid: - in powder form; - or in the form of a water-in-oil inverse emulsion; - or in the form of an aqueous or oily multiphase particulate suspension; said ATBS.K crystal form having a X-ray powder diffraction pattern with characteristic peaks at 13.1°, 14.4°, 16.3°, 19.8°, 23.5°, 24.3°, 26.9°, 27.6°, 29.3°, 30.6°, 31.6°, 34.3°, 36.1°, 41.7°, 44.6°, 46.7° 2Θ (±0.1°).

18. A method for hydraulic fracturing of unconventional subterranean oil and gas reservoirs, comprising preparing a fracturing fluid as claimed in claim 16 and injecting the fracturing fluid into a subterranean reservoir. ​ ​ ​ ​ ​ ​ ​ ​ ​ 19. A method of reducing the frictional drag of a fracturing fluid in a hydraulic fracturing operation in an unconventional subterranean oil and gas reservoir comprising preparing the fracturing fluid of claim 16 and injecting the fracturing fluid into a subterranean reservoir.

20. Use of a polymer of claim 12 in any of the following: drilling; cementing; profile control; flow diversion; open, closed or semi-closed circuit water treatment; fermentation broth treatment; sludge treatment; construction; paper or paperboard manufacture; batteries; wood treatment; hydraulic composition treatment; cosmetic formulation; detergent formulation; textile manufacture; geothermal energy; diaper manufacture; agriculture.

21. Use of a polymer of claim 12 as a flocculant, binder, absorbent, drainage aid, retention aid, dewatering aid, conditioning agent, stabilizer, fixative, film former, sizing agent, water reducing agent, clay inhibiting agent or dispersant.

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