Preparation of a polymer by photopolymerisation

Abstract

The invention relates to the preparation of a water-soluble polycarboxylic polymer by a radical photopolymerisation reaction, at a wavelength ranging from 220 nm to 320 nm, of an unsaturated carboxylic acid. The polymer prepared according to the invention has a well-controlled molar mass and can be used in an aqueous grinding aid, scale inhibitor or dispersing agent, in particular for the treatment of a mineral material or an organic material.

Description

[0001] PREPARATION OF A POLYMER BY PHOTOPOLYMERIZATION

[0002] The invention relates to the preparation of a water-soluble polycarboxylic polymer by a radical photopolymerization reaction, at a wavelength ranging from 220 nm to 320 nm, and of an unsaturated carboxylic acid. The polymer prepared according to the invention has a well-controlled molar mass and can be used in an aqueous grinding aid, anti-scaling agent, or dispersant, particularly for the treatment of mineral or organic materials.

[0003] Frequently, the processing of mineral or organic materials, particularly with grinding aids, scale inhibitors, or dispersing agents, requires the development of polymers with enhanced properties. These agents are often essential for controlling the rheology of particle suspensions, especially their viscosity, yield stress, and stability. They also allow for controlling the particle size distribution of suspensions and ensuring proper dispersion, whether in concentrated or dilute solutions. The properties of these processing agents can be significantly affected by variations in their inherent characteristics, as well as by the presence of impurities or byproducts, particularly those resulting from their preparation, such as certain inorganic compounds or mineral salts.

[0004] Improving the efficiency of polymer preparation methods used in these agents should be a priority. This includes reducing direct and indirect energy consumption related to polymerization reactions, improving the yield of these reactions, decreasing the number and quantities of reagents and solvents used, and reducing or eliminating by-products formed during these polymerization reactions.

[0005] In particular, limiting or eliminating the use of certain initiating compounds or chain transfer agents during polymerization reactions is an important objective in polymer preparation. Indeed, mineral salts, especially sulfur and phosphorus salts, metals, particularly iron and copper, or certain chemical elements such as sulfur and phosphorus, which are commonly found in some initiating compounds and chain transfer agents, can be detrimental to the use of these polymers, especially when using them as treatment agents for mineral or organic particles. Obtaining polymers with well-controlled peak average molar mass (Mp) and polymolecularity index (Ip) is also an important goal in polymer preparation.

[0006] Furthermore, from an environmental or toxicological point of view, it is important to have particle treatment agents, and therefore suitable polymers, which are prepared using reagents or solvents that are not harmful either at the time of their preparation or during the use of the polymers obtained.

[0007] Document JP 2009102466 describes a water-absorbing resin for hygiene products prepared by polymerizing a monomer salt under ultraviolet irradiation, resulting in a gel that is dried and then sprayed. Document EP 0534695 describes a method for polymerizing acrylic acid or sodium acrylate in water in the presence of a copper salt or a cobalt salt.

[0008] The method for preparing a water-soluble polycarboxylic polymer according to the invention makes it possible to provide a solution to all or part of the problems of the preparation methods of the prior art.

[0009] Thus, the invention provides a method for preparing an aqueous composition C comprising a water-soluble polymer P with a molar mass Mp, measured by CES, ranging from 1,000 g / mol to 3,000,000 g / mol and prepared in the presence of at least one compound I selected from hydrogen peroxide, benzoyl peroxide, acetyl peroxide, lauryl peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, and combinations thereof, by a photo-induced radical polymerization reaction carried out in an aqueous medium and at a temperature below 60°C, under irradiation at a wavelength ranging from 220 nm to 320 nm and at an intensity ranging from 0.01 W / cm² 2 at 20 W / cm 2 , of at least one anionic compound Ml comprising at least one polymerizable olefinic unsaturation and at least one carboxylic acid function or one of its salts.

[0010] Essentially, according to the invention, the preparation method uses at least one monomer ML. Preferably, for the method according to the invention, the monomer ML is selected from acrylic acid, methacrylic acid, a salt of acrylic acid, a salt of methacrylic acid, an acrylic acid oligomer, a methacrylic acid oligomer, a salt of an acrylic acid oligomer, a salt of a methacrylic acid oligomer, and combinations thereof. Preferably, the monomer ML is selected from acrylic acid, a salt of acrylic acid, an acrylic acid oligomer, a salt of an acrylic acid oligomer, and combinations thereof. Acrylic acid is the preferred monomer ML. The preparation method according to the invention may also use one or more other monomers different from monomer ML, preferably in a minor weight relative to the amount of monomer ML used.Preferably, the polymerization reaction may also utilize at least one other compound selected from:

[0011] • another anionic compound M2 different from M1, preferably a compound M2 chosen from itaconic acid, maleic acid, maleic anhydride and their combinations;

[0012] • a sulfur compound M3, preferably an M3 compound selected from 2-acrylamido-2-methylpropane sulfonic acid, a salt of 2-acrylamido-2-methylpropane sulfonic acid, 2-(methacryloyloxy)ethanesulfonic acid, a salt of 2-(methacryloyloxy)ethanesulfonic acid, sodium methallyl sulfonate, sodium vinyl sulfonate, styrene sulfonate, acrylonitrile, acrylamide, N-methylolacrylamide, ureidomethacrylate and their combinations;

[0013] • a non-ionic M4 compound comprising at least one polymerizable olefinic unsaturation, preferably at least one polymerizable ethylenic unsaturation and in particular a polymerizable vinyl function, more preferably a non-ionic M4 compound selected from styrene, vinylcaprolactam, esters of an acid comprising at least one monocarboxylic acid function, in particular an ester of an acid selected from acrylic acid, methacrylic acid, and their combinations, for example hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, alkyl acrylate, in particular Ci-Cio-alkyl acrylate, preferably Ci-C4-alkyl acrylate, more preferably methyl acrylate, ethyl acrylate, w-propyl acrylate, isopropyl acrylate, isobutyl acrylate, α-butyl acrylate, alkyl methacrylate, in particular Ci-Cio-alkyl methacrylate, preferably Ci-C4-alkyl methacrylate,more preferably methyl methacrylate, ethyl methacrylate, α-propyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, α-butyl methacrylate, aryl acrylate, preferably phenyl acrylate, benzyl acrylate, phenoxyethyl acrylate, aryl methacrylate, preferably phenyl methacrylate, benzyl methacrylate, phenoxyethyl methacrylate; • a compound M5 of formula I:,

[0014] R 1

[0015]

[0016] (I)

[0017] in which:

[0018] - R 1 and R 2 , identical or different, independently represent H or CH3,

[0019] - L 1 independently represents a grouping chosen from C(O), CH2, CH2-CH2 and O-CH2-CH2-CH2-CH2

[0020] - L 2 independently represents a group chosen from (CH2-CH2O) X , (CH2CH(CH3)O) y , (CH(CH3)CH2O) Zand their combinations and

[0021] - x, y and z, identical or different, independently represent 0 or an integer or decimal number between 1 and 150 and the sum x+y+z is between 10 and 150;

[0022] • a phosphorus compound M6, preferably an M6 compound selected from phosphated hydroxyethylacrylate, phosphated hydroxyethylmethacrylate, phosphated hydroxypropylacrylate, phosphated hydroxypropylmethacrylate, phosphated hydroxybutylmethacrylate and their combinations;

[0023] • a crosslinking compound M7 or an M7 compound comprising at least two olefinic unsaturations; preferably in an amount of less than 5% by weight, also preferably from 0.01% by weight to 4% by weight, in particular from 0.02% by weight to 4% by weight or from 0.02% by weight to 2% by weight, in particular from 0.02% by weight to 1% by weight, of compound M7 relative to the total amount by weight of monomers.

[0024] Preferably, polymer P is not crosslinked; it is prepared in the absence of a crosslinking compound or in the absence of a compound comprising at least two olefinic unsaturations.

[0025] Essentially, the preparation method according to the invention involves a radical photopolymerization reaction. The polymerization reaction according to the invention is therefore carried out under light irradiation. According to the invention, the polymerization reaction can be performed partially or totally under light irradiation. Furthermore, the irradiation can be continuous or sequential. Preferably, according to the invention, the photopolymerization reaction is carried out under irradiation at an intensity ranging from 0.03 W / cm². 2 at 15 W / cm² 2 ; preferably ranging from 0.03 W / cm² 2 at 10 W / cm² 2 or 0.03 W / cm² 2 at 5 W / cm 2 .

[0026] Also preferably according to the invention, the photopolymerization reaction is carried out under irradiation at a wavelength from 230 nm to 300 nm; more preferably from 240 nm to 290 nm or from 250 nm to 280 nm.

[0027] Advantageously, according to the invention, the photopolymerization reaction is carried out under irradiation obtained by means of at least one light source whose power can be adapted to the various conditions encountered. In particular, the power of this source can be specifically chosen. Thus, the light source can have a power ranging from a few watts to several hundred watts. For example, it is possible to conduct the photopolymerization reaction under irradiation using one or more light sources with a power ranging from 5 W to 1000 W.

[0028] Preferably, according to the invention, irradiation is generated by means of a source selected from among LEDs, mercury vapor lamps, metal-doped mercury vapor lamps (e.g., iron-doped), microwave lamps, lasers, and combinations thereof. The preferred source is selected from LEDs, mercury vapor lamps, and combinations thereof. Essentially, according to the invention, the photopolymerization reaction is carried out at a temperature below 60°C. Preferably, the photopolymerization reaction is carried out at a temperature below 55°C. Preferably, the temperature ranges from 20°C to 50°C, or from 20°C to 45°C, or from 15°C to 45°C, or from 10°C to 40°C. Particularly advantageously, the photopolymerization reaction is carried out without any external heating source.

[0029] Preferably according to the invention, the photopolymerization reaction is carried out at a pH less than 6, preferably less than 5 or ranging from 1 to 4.

[0030] In a novel approach, the photopolymerization reaction according to the invention is carried out in an aqueous medium. Preferably, the photopolymerization reaction is carried out in water, alone or combined with at least one polar, protic solvent. Preferably, the polar solvent is an alcohol, more preferably isopropanol. Preferably, the photopolymerization reaction is carried out in water alone.

[0031] During photopolymerization, the reaction conditions can be adjusted. Preferably, the monomer concentration, preferably Ml monomer, during the photopolymerization reaction is greater than 2% by weight or greater than 5% by weight relative to the total amount of the reaction medium. More preferably, it is greater than 10% by weight relative to the total amount of the reaction medium.

[0032] Preferably, the concentration of monomers, preferably monomer Ml, during the photopolymerization reaction is less than 50% by weight relative to the total amount of the reaction medium. More preferably, it is less than 40% by weight or less than 35% by weight, more preferably less than 30% by weight, relative to the total amount of the reaction medium.

[0033] Generally according to the invention, the concentration of compound I during the photopolymerization reaction is greater than 0.01% by weight, preferably greater than 0.1% by weight, relative to the total amount of the reaction medium.

[0034] The concentration of compound I during the photopolymerization reaction is generally less than 10% by weight, preferably less than 5% by weight or less than 2% by weight, relative to the total amount of the reaction medium.

[0035] Preferably, for the preparation method according to the invention, the photopolymerization reaction is carried out in the presence of at least one compound I. Preferably, compound I is used in a concentration ranging from 0.1% by weight to 10% by weight relative to the weight of monomers. More preferably, it is used in a concentration ranging from 0.5% by weight to 8% by weight or from 1% by weight to 6% by weight, relative to the weight of monomers.

[0036] A particularly advantageous feature of the photopolymerization reaction implemented according to the invention is to limit the number and quantities of reagents used, particularly reagents that are detrimental during the preparation or use of polymer P. Preferably, for the method according to the invention, the photopolymerization reaction is carried out in the absence of a photoinitiator compound. Also preferably, the photopolymerization reaction is carried out in the absence of a compound selected from 4,4'-azobis-4-cyanopentanoic acid (ACPA), alkali metal persulfate (in particular sodium persulfate, potassium persulfate, ammonium persulfate), an azo compound, and their respective combinations or associations with an ion selected from Fe 11 Fe 111 Cu 1 Cu 11However, the photopolymerization reaction can be carried out in the presence of a small amount of these compounds, less than 1% by weight, or even less than 0.5% by weight, relative to the amount by weight of monomers.

[0037] Also preferably for the method according to the invention, the photopolymerization reaction is carried out in the absence of a chain transfer agent. Preferably, the photopolymerization is carried out in the absence of a compound comprising P 1 ,a compound containing P 111 , of a compound including S IV ; preferably in the absence of a compound comprising phosphite, a compound comprising hypophosphite, a compound comprising hydrogen sulfite; more preferably in the absence of phosphorous acid, sodium phosphite, hypophosphorous acid, sodium hypophosphite, sodium hydrogen sulfite.

[0038] Also preferably, the photopolymerization reaction is carried out in the absence of a metal ion, preferably in the absence of copper or cobalt ions, and in particular in the absence of Fe 11 Fe 111 Cu 1 Cu 11 .

[0039] The preparation method according to the invention makes it possible to obtain a polymer P whose average weight molar mass Mp at the peak and polymolecularity index Ip can be well controlled within ranges that can vary quite widely, particularly depending on the reaction conditions chosen. Thus, according to the invention, the polymer P has a molar mass Mp, measured by CES, ranging from 1,000 g / mol to 3,000,000 g / mol. Preferably, the molar mass Mp of the polymer P ranges from 1,000 g / mol to 2,000,000 g / mol or from 1,000 g / mol to 1,500,000 g / mol; preferably from 2,000 g / mol to 1,500,000 g / mol or from 1,000 g / mol to 1,000,000 g / mol.

[0040] According to the invention, the polymer P has a polymolecularity index Ip, measured by CES, of less than 40 or ranging from 1.2 to 40 or from 1.5 to 40 or from 1.2 to 35. Preferably, the polymolecularity index Ip of the polymer P ranges from 1.5 to 30; preferably from 1.2 to 25 or even from 1.5 to 20.

[0041] According to the invention, the weight or molar mass of polymer P up to 100,000 g / mol and its polymolecularity index Ip are determined by Size Exclusion Chromatography (SEC). A test portion of the polymer dispersion corresponding to 90 mg of dry matter is introduced into a 10 mL bottle. Mobile phase, supplemented with 0.04% dimethylformamide (DMF), is added up to a total mass of 10 g. The composition of this mobile phase is as follows: NaHCO3: 0.05 mol / L, NaNO3: 0.1 mol / L, triethanolamine: 0.02 mol / L, NaNa: 0.03 wt%.The CES system consists of a Waters 510 isocratic pump with a flow rate set at 0.8 mL / min, a Waters 717+ autosampler, and a furnace containing a 6 cm long, 40 mm internal diameter Waters Guard Column Ultrahydrogel pre-column, followed by a 30 cm long, 7.8 mm internal diameter Waters Ultrahydrogel linear column. Detection is performed using a Waters 410 RI differential refractometer. The furnace is heated to 60°C and the refractometer to 45°C. The CES device is calibrated with a series of sodium polyacrylate standards supplied by "Polymer Standard Service" with peak molar weights between 900 and 2,250,000 g / mol and polymolecularity indices between 1.4 and 1.7. The calibration curve is linear and takes into account the correction obtained using the flow marker: dimethylformamide (DMF).The acquisition and processing of the chromatogram are carried out using the software "PSS WinGPC Scientific" v 4.02. The resulting chromatogram is integrated into the area corresponding to molar weights greater than 250 g / mol.

[0042] According to the invention, the weight or molar mass of polymer P above 100,000 g / mol and its polymolecularity index Ip are determined by Size Exclusion Chromatography (SEC). A test portion of the polymer solution corresponding to 20 mg of dry matter is introduced into a 10 mL bottle. Mobile phase, supplemented with 0.04% dimethylformamide (DMF), is added up to a total mass of 10 g. The composition of this mobile phase is as follows: NaHCO3: 0.05 mol / L, NaNO3: 0.1 mol / L, triethanolamine: 0.02 mol / L, NaNa: 0.03 wt%. The CES chain consists of a Waters 510 type isocratic pump, with a flow rate set at 1 mL / min, a Waters 717+ sample changer, a furnace containing a PSS Suprema guard column 5 cm long and 8 mm in internal diameter, followed by a PSS Suprema 30000 Â column 30 cm long and 8 mm in internal diameter.Detection is performed using a Waters RI 410 differential refractometer. The oven is heated to 60°C and the refractometer to 45°C. The CES device is calibrated with a series of sodium polyacrylate standards supplied by Polymer Standards Service, with peak molar weights ranging from 1200 g / mol to 1390,000 g / mol and polymolecularity indices (Ip) ranging from 1.09 to 2. The calibration curve is linear and incorporates the correction obtained using the flow marker dimethylformamide (DMF). Chromatogram acquisition and processing are performed using ConSenxus hs NTeqGPC software version 5.1.5. The resulting chromatogram is integrated into the region corresponding to molar weights greater than 180 g / mol.

[0043] The invention provides a particularly efficient method for preparing a composition C comprising a water-soluble polymer P. Composition C constitutes another aspect of the invention. Thus, the invention also provides a composition C prepared according to the preparation method of the invention.

[0044] Preferably, composition C according to the invention comprises an amount of sulfur-containing polymer, phosphorus-containing polymer, or residual monomer, measured by high-performance liquid chromatography (HPLC), that is less than 5% by weight, preferably less than 1% by weight, relative to the weight of monomers. Preferably, according to the invention, composition C comprises an amount, measured by high-performance liquid chromatography (HPLC), of sulfur-containing polymer, phosphorus-containing polymer, or residual monomer that is zero.

[0045] According to the invention, the quantities of sulfur-containing polymer, phosphorus-containing polymer, or residual monomer are measured using techniques known as such, for example, High-Performance Liquid Chromatography (HPLC). In this method, the constituent components of the mixture are separated on a stationary phase and detected by a UV detector. After calibration of the detector, the corresponding quantity of the residual compound can be obtained, for example, from the peak area corresponding to the analyzed compound.

[0046] Preferably, composition C according to the invention comprises an amount of mineral salts, preferably mineral salts resulting from the polymerization reaction, of less than 2% by dry weight or 1% by dry weight, preferably less than 0.5% by dry weight or 0.3% by dry weight, relative to the amount of monomers. More preferably, composition C according to the invention comprises zero mineral salts, preferably zero mineral salts resulting from the polymerization reaction.

[0047] According to the invention, the quantities of mineral salts are determined by ion chromatography. A test portion of the aqueous dispersion resulting from the polymerization reaction, comprising approximately 80 mg of the polymer, is introduced into a 15 mL bottle. Mobile phase is then added to a total mass of 15 g. The mobile phase composition is as follows: sodium carbonate: 0.009 mol / L. The ion chromatography system for anion determination consists of a Dionex Aquion ion chromatography system with an integrated degasser, the flow rate of which is set at 1 mL / min. This system includes a chemical suppressor, an AG9-HC pre-column, a CG3 metal-trapping pre-column, an NG1 pre-column, and an AG9-HC column. Detection is achieved using a conductivity detector. The ion chromatography system is calibrated with a series of sodium sulfate solution standards. The calibration range is between 0.5 ppm and 100 ppm.The calibration curve is linear. Automatic sample dilution by the instrument ensures that the samples remain within the calibration range. Chromatogram acquisition and processing are performed using Chromeleon software version 7.2.10.

[0048] Composition C according to the invention has properties that are particularly useful in many technical fields, especially for the processing of mineral or organic materials.

[0049] The invention then provides an aqueous grinding aid or anti-scale or dispersing agent comprising at least one composition C according to the invention.

[0050] Preferably, according to the invention, composition C can be used for the treatment of a mineral or organic material, whether synthetic or of natural origin. Thus, the invention provides a method for treating a mineral or organic material, whether synthetic or of natural origin, comprising contacting this material with at least one composition C according to the invention.

[0051] Preferably for the treatment method according to the invention, the mineral or organic material is selected from alkaline earth metal carbonate, more preferably calcium carbonate (natural calcium carbonate or precipitated calcium carbonate), strontium carbonate, magnesium carbonate, barium carbonate, dolomite, kaolin, titanium dioxide, talc, lime, calcium sulfate, barium sulfate, magnesium silicate, calcium silicate, calcium phosphate, hydraulic binder, carbon particles, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanotubes, carbon nanofibers, graphene, tempered carbon, graphite carbon fibers, graphite carbon particles, metal fibers, metal particles, silicon particles, an electroactive material, for example an electroactive material selected from lithium, iron, nickel, manganese, cobalt and their combinations, preferably selected from iron, nickel, manganese,cobalt and their combinations, preferably chosen from LiFePCh (LFP), Li(Ni,Mn,Co)O2 (NMC).

[0052] The advantageous, particular or preferred characteristics of the method of preparing composition C or polymer P according to the invention define compositions C according to the invention and aqueous agents as well as processing methods which are also advantageous, particular or preferred.

[0053] The following examples illustrate the different aspects of the invention. EXAMPLES

[0054] Preparation of a PI polymer according to the invention under irradiation at 250 nm

[0055] In a quartz tank, under an inert nitrogen atmosphere, a reaction medium is prepared with stirring from two aqueous solutions. This medium comprises 0.5% by weight of hydrogen peroxide and 10% by weight of acrylic acid. The tank is irradiated for 50 minutes at 4 mW / cm². 2using an LED string (“TaoYuan China”) emitting at 250 nm. We obtain the PI polymer whose molar mass at the peak measured by CES is 2,730,000 g / mol.

[0056] Preparation of P2 to P4 polymers according to the invention under irradiation at 280 nm. In a quartz cell, under an inert nitrogen atmosphere, and from two aqueous solutions, a reaction medium comprising 0.5 wt% hydrogen peroxide and 10 wt% acrylic acid is prepared with stirring. The cell is irradiated for 17 minutes at 35 mW / cm². 2 using a mercury lamp (“Omni cure” S 1000) emitting at 280 nm. We obtain the polymer P2 whose molar mass at the peak measured by CES is 878000 g / mol.

[0057] Similarly, polymer P3 is prepared by irradiating a reaction medium containing 5 wt% hydrogen peroxide and 10 wt% acrylic acid for 40 minutes. The resulting polymer P3 has a peak molar mass of 11,500 g / mol, as measured by CES. The residual acrylic acid concentration, measured by gas chromatography, is 7 ppm.

[0058] Similarly, polymer P4 is prepared by irradiating a reaction medium containing 1 wt% hydrogen peroxide and 5 wt% acrylic acid for 40 minutes. The resulting polymer P4 has a peak molar mass of 2300 g / mol, as measured by CES.

[0059] Preparation of P5 to P9 polymers according to the invention under irradiation at 275 nm. In a quartz cell, under an inert nitrogen atmosphere, and from two aqueous solutions, a reaction medium comprising 0.5 wt% hydrogen peroxide and 10 wt% acrylic acid is prepared with stirring. The cell is irradiated for 65 minutes at 4 mW / cm². 2 using an LED source (“TaoYuan China”) emitting at 275 nm. We obtain the P5 polymer whose molar mass at peak measured by CES is 1,001,400 g / mol.

[0060] Similarly, polymer P6 is prepared by irradiating a reaction medium containing 1 wt% hydrogen peroxide and 10 wt% acrylic acid for 65 minutes. The resulting polymer P6 has a peak molar mass of 502,000 g / mol, as measured by CES. The residual acrylic acid concentration, measured by gas chromatography, is 580 ppm.

[0061] Similarly, polymer P7 is prepared by irradiating a reaction medium containing 1 wt% hydrogen peroxide and 10 wt% acrylic acid for 30 minutes. This yields polymer P7 with a peak molar mass measured by CES of 419,000 g / mol.

[0062] Similarly, polymer P8 is prepared by irradiating a reaction medium containing 5 wt% hydrogen peroxide and 10 wt% acrylic acid for 60 minutes. The resulting polymer P8 has a peak molar mass of 204,000 g / mol, as measured by CES. The residual acrylic acid concentration, measured by gas chromatography, is 1240 ppm.

[0063] Similarly, polymer P9 is prepared by irradiating a reaction medium containing 1 wt% hydrogen peroxide and 5 wt% acrylic acid for 65 minutes. The resulting polymer P9 has a peak molar mass of 104,000 g / mol, as measured by CES.

[0064] Preparation of P10 and Pli polymers according to the invention under irradiation at 275 nm. In a quartz flask, under an inert nitrogen atmosphere, and from two aqueous solutions, a reaction medium comprising 5 wt% hydrogen peroxide and 5 wt% acrylic acid is prepared with stirring. The flask is irradiated for 80 minutes at 51.3 mW / cm². 2 Using an LED source (COB TaoYuan China) emitting at 275 nm and placed 0.5 cm from the balloon, the P10 polymer was obtained, with a peak molar mass of 2000 g / mol measured by CES. The residual acrylic acid content measured by gas chromatography was less than 1 ppm.

[0065] Similarly, the Pli polymer is prepared by irradiating it for 80 minutes at 37.2 mW / cm² 2and at a distance of 2.5 cm from the balloon. The Pli polymer is obtained, with a peak molar mass measured by CES of 4700 g / mol. The residual acrylic acid content measured by gas chromatography is 70 ppm.

[0066] By using different irradiation sources, the preparation method according to the invention makes it possible to prepare, in a controlled manner, polymers whose molar mass can vary over a very wide range. The quantities of residual acrylic acid are particularly low.

Claims

DEMANDS 1. Method for preparing an aqueous composition C comprising a water-soluble polymer P of molar mass Mp, measured by CES, ranging from 1000 g / mol to 3,000,000 g / mol and prepared in the presence of at least one compound I selected from hydrogen peroxide, benzoyl peroxide, acetyl peroxide, lauryl peroxide, tert-butyl hydroperoxide, cumene hydroperoxide and combinations thereof, by a photo-induced radical polymerization reaction carried out in aqueous medium and at a temperature below 60°C, under irradiation at a wavelength ranging from 220 nm to 320 nm and at an intensity ranging from 0.01 W / cm² 2 at 20 W / cm 2 , of at least one anionic compound Ml comprising at least one polymerizable olefinic unsaturation and at least one carboxylic acid function or one of its salts.

2. Method according to claim 1 wherein the monomer Ml is selected from acrylic acid, methacrylic acid, a salt of acrylic acid, a salt of methacrylic acid, an oligomer of acrylic acid, an oligomer of methacrylic acid, a salt of an acrylic acid oligomer, a salt of a methacrylic acid oligomer and combinations thereof; preferably selected from acrylic acid, a salt of acrylic acid, an oligomer of acrylic acid, a salt of an acrylic acid oligomer and combinations thereof; more preferably acrylic acid.

3. A method according to claim 1 or 2, wherein: - The photopolymerization reaction is carried out under irradiation at an intensity ranging from 0.03 W / cm² 2 at 15 W / cm² 2 ; preferably ranging from 0.03 W / cm² 2 at 10 W / cm² 2 or 0.03 W / cm² 2 at 5 W / cm 2 ; Or - the photopolymerization reaction is carried out under irradiation at a wavelength ranging from 230 nm to 300 nm; more preferably ranging from 240 nm to 290 nm or from 250 nm to 280 nm; or - the photopolymerization reaction is carried out under irradiation using one or more light sources with a power ranging from 5 W to 1000 W; or - Irradiation is generated by means of a source chosen from among LEDs, mercury vapor lamps, metal-doped mercury vapor lamps (e.g., iron-doped), microwave lamps, lasers, and combinations thereof; or - the photopolymerization reaction is carried out at a temperature below 60°C or below 55°C; preferably at a temperature ranging from 20°C to 50°C or from 20°C to 45°C, or from 15°C to 45°C, or from 10°C to 40°C; or - the photopolymerization reaction is carried out at a pH below 6, preferably below 5 or ranging from 1 to 4; or - the photopolymerization reaction is carried out in water, alone or combined with at least one polar, protic solvent, preferably an alcohol, more preferably isopropanol; or - the concentration of monomers, preferably monomer Ml, during the photopolymerization reaction is greater than 2% by weight or greater than 5% by weight, preferably greater than 10% by weight, relative to the total quantity of the reaction medium; or - the concentration of monomers, preferably monomer Ml, during the photopolymerization reaction is less than 50% by weight, preferably less than 40% by weight or less than 35% by weight, more preferably less than 30% by weight, relative to the total quantity of the reaction medium; or - the concentration of compound I during the photopolymerization reaction is greater than 0.01% by weight, preferably greater than 0.1% by weight, relative to the total amount of the reaction medium; or - the concentration of compound I during the photopolymerization reaction is less than 10% by weight, preferably less than 5% by weight or less than 2% by weight, relative to the total quantity of the reaction medium.

4. Method according to any one of claims 1 to 3 wherein the photopolymerization reaction is carried out in the presence of at least one compound I; preferably a compound I used in a concentration ranging from 0.1 wt% to 10 wt%, preferably from 0.5 wt% to 8 wt% or from 1 wt% to 6 wt%, relative to the weight amount of monomers.

5. A method according to any one of claims 1 to 4, wherein: - The photopolymerization reaction is carried out in the absence of a compound chosen from 4,4'-azobis-4-cyanopentanoic acid (ACPA), alkali metal persulfate (in particular sodium persulfate, potassium persulfate, ammonium persulfate), an azo compound and their respective combinations or associations with an ion chosen from Fe 11 Fe 111 Cu 1 Cu 11 ; Or - The photopolymerization reaction is carried out in the absence of a chain transfer agent; preferably in the absence of a compound containing P 1 , of a compound including P 111 , of a compound including S IV ; preferably in the absence of a compound comprising phosphite, a compound comprising hypophosphite, a compound comprising hydrogen sulfite; more preferably in the absence of phosphorous acid, sodium phosphite, hypophosphorous acid, sodium hypophosphite, sodium hydrogen sulfite.

6. A method according to any one of claims 1 to 5, wherein the polymerization reaction also uses at least one other compound selected from: • another anionic compound M2 different from M1, preferably a compound M2 chosen from itaconic acid, maleic acid, maleic anhydride and their combinations; • a sulfur compound M3, preferably an M3 compound selected from 2-acrylamido-2-methylpropane sulfonic acid, a salt of 2-acrylamido-2-methylpropane sulfonic acid, 2-(methacryloyloxy)ethanesulfonic acid, a salt of 2-(methacryloyloxy)ethanesulfonic acid, sodium methallyl sulfonate, sodium vinyl sulfonate, styrene sulfonate, acrylonitrile, acrylamide, N-methylolacrylamide, ureidomethacrylate and their combinations; • a non-ionic compound M4 comprising at least one polymerizable olefinic unsaturation, preferably at least one polymerizable ethylenic unsaturation, and in particular a polymerizable vinyl function, more preferably a non-ionic compound M4 selected from styrene, vinylcaprolactam, esters of an acid comprising at least one monocarboxylic acid function, in particular an ester of an acid selected from acrylic acid, methacrylic acid, and their combinations, for example hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, alkyl acrylate, in particular Ci-Cio-alkyl acrylate, preferably Ci-C4-alkyl acrylate, more preferably methyl acrylate, ethyl acrylate, β-propyl acrylate, isopropyl acrylate, isobutyl acrylate, β-butyl acrylate, alkyl methacrylate, in particular Ci-Cio-alkyl methacrylate, preferably Ci-C4-alkyl methacrylate,more preferably methyl methacrylate, ethyl methacrylate, α-propyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, α-butyl methacrylate, aryl acrylate, preferably phenyl acrylate, benzyl acrylate, phenoxyethyl acrylate, aryl methacrylate, preferably phenyl methacrylate, benzyl methacrylate, phenoxyethyl methacrylate; • a compound M5 of formula I: R 1 in which: - R 1 and R 2 , identical or different, independently represent H or CH3, - L 1 independently represents a grouping chosen from C(O), CH2, CH2-CH2 and O-CH2-CH2-CH2-CH2 - L 2 independently represents a group chosen from (CH2-CH2O) X , (CH2CH(CH3)O) y , (CH(CH3)CH2O) Z and their combinations and - x, y and z, identical or different, independently represent 0 or an integer or decimal number between 1 and 150 and the sum x+y+z is between 10 and 150; • a phosphorus compound M6, preferably an M6 compound selected from phosphated hydroxyethylacrylate, phosphated hydroxyethylmethacrylate, phosphated hydroxypropylacrylate, phosphated hydroxypropylmethacrylate, phosphated hydroxybutylmethacrylate and their combinations.

7. A method according to any one of claims 1 to 6, wherein: - the polymer P has a molar mass Mp, measured by CES, ranging from 1,000 g / mol to 3,000,000 g / mol or ranging from 1,000 g / mol to 2,000,000 g / mol or from 1,000 g / mol to 1,500,000 g / mol; preferably from 2,000 g / mol to 1,500,000 g / mol or from 1,000 g / mol to 1,000,000 g / mol; or- the polymer P has a polymolecularity index Ip, measured by CES, of less than 40 or ranging from 1.2 to 40 or from 1.5 to 40; preferably from 1.2 to 35 or from 1.5 to 30; preferably from 1.2 to 25 or even from 1.5 to 20.

8. Composition C prepared according to the method according to any one of claims 1 to 7.

9. Composition C according to claim 8 comprising an amount, measured by high-performance liquid chromatography (HPLC), of sulfur polymer or phosphorus polymer or residual monomer which is zero or comprising an amount of sulfur polymer or phosphorus polymer or residual monomer which is less than 5% by weight, preferably less than 1% by weight, relative to the amount by weight of monomers or comprising an amount of mineral salts, preferably mineral salts resulting from the polymerization reaction, of less than 2% by dry weight or 1% by dry weight, preferably less than 0.5% by dry weight or 0.3% by dry weight, relative to the amount of monomers, more preferably a zero amount of mineral salt, preferably a zero amount of mineral salt resulting from the polymerization reaction.

10. Aqueous grinding aid or anti-scale or dispersing agent, in particular for the treatment of a mineral or organic material, synthetic or of natural origin, comprising at least one composition C according to one of claims 8 or 9.

11. Method of treating a mineral or organic material, synthetic or of natural origin, comprising bringing this material into contact with at least one composition C according to one of claims 8 or 9.

12. A method according to claim 11, wherein the mineral or organic material is selected from alkaline earth metal carbonate, more preferably calcium carbonate (natural calcium carbonate or precipitated calcium carbonate), strontium carbonate, magnesium carbonate, barium carbonate, dolomite, kaolin, titanium dioxide, talc, lime, calcium sulfate, barium sulfate, magnesium silicate, calcium silicate, calcium phosphate, hydraulic binder, carbon particles, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanotubes, carbon nanofibers, graphene, tempered carbon, graphite carbon fibers, graphite carbon particles, metal fibers, metal particles, silicon particles, an electroactive material, for example, an electroactive material selected from lithium, iron, nickel, manganese, cobalt and combinations thereof, preferably selected from iron, nickel, manganese,cobalt and their combinations, preferably chosen from LiFePC (LFP), Li(Ni,Mn,Co)O2 (NMC).

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