DISPERSION OF MINERAL PARTICLES

Abstract

The invention relates to a method for preparing a concentrated aqueous mineral composition comprising the thermal or mechanical concentration of a previously ground mineral composition in a humid medium at medium or low concentration. A particular poly(itaconate) is used during the concentration or dispersion of this mineral composition. The invention also provides an aqueous concentrating or dispersing agent comprising this particular poly(itaconate) and the use of the aqueous mineral composition for papermaking.

Description

Title of the invention: DISPERSION OF MINERAL PARTICLES

[0001] The invention relates to a method for preparing a concentrated aqueous mineral composition comprising the thermal or mechanical concentration of a previously ground mineral composition in a humid medium at medium or low concentration. A particular poly(itaconate) is used during the concentration or dispersion of this mineral composition. The invention also provides an aqueous concentrating or dispersing agent comprising this particular poly(itaconate) and the use of the aqueous mineral composition for papermaking.

[0002] Methods for preparing aqueous compositions of ground mineral material in a humid environment at medium or low concentrations, followed by mechanical or thermal concentration, are known. These methods generally employ concentrating or dispersing agents, particularly to control the rheology of the aqueous composition during its preparation or storage. In general, methods for preparing mineral material compositions must be efficient and allow for good viscosity control. Viscosity drift phenomena must be controlled because they can lead to gelation of the prepared compositions, making handling difficult or even impossible. Similarly, sedimentation of mineral particles must be avoided or significantly slowed.In addition to stability control, viscosity control of aqueous compositions of ground mineral particles is also essential. Therefore, the stability of mineral compositions is a key characteristic not only during their preparation but also during their transport and storage.

[0003] Another desirable property for mineral matter compositions is their high mineral concentration. It is therefore important to be able to prepare aqueous compositions of mineral matter particles with a high dry extract. A high dry extract of these compositions makes it possible, in particular, to increase the productivity of the methods that use these compositions, as well as to limit the costs and resources required for their preparation or transport.

[0004] Mineral material compositions can be used alone, but they can also be combined with different mineral material compositions. Thus, in addition to the problems encountered by each of the mineral material compositions Considered individually, combining several of these compositions can generate additional problems. Therefore, preparing concentrated mineral compositions becomes even more complex when several of these compositions must be combined. The compatibility of concentrated aqueous mineral compositions is thus a particularly desirable property. In particular, controlling the viscosity and stability of concentrated compositions containing multiple minerals is especially difficult to achieve.

[0005] To address these problems, various agents are used during one or more steps in the preparation of concentrated aqueous compositions of mineral matter, particularly during grinding, mechanical or thermal concentration, or dispersion of these compositions. Most often, the agents used are chosen from among grinding aids and concentration or dispersion agents. For example, there are polymeric agents prepared using carboxylic acid, notably (meth)acrylic polymers. However, it is important to have alternative agents available to improve the methods for preparing these compositions, as well as the methods for preparing the polymers used.

[0006] Within aqueous compositions of mineral matter, grinding aids and concentrating agents should develop significant interactions with the mineral matter particles. In particular, these interactions should make it possible to reduce the amount of free agent, i.e., agent not adsorbed onto the mineral matter.

[0007] Finally, from an environmental point of view, it is important to be able to have polymers prepared from reagents of renewable or natural origin, in particular reagents of plant origin.

[0008] Furthermore, during papermaking, aqueous mineral filler compositions are used either to coat the paper or to provide mineral filler within the pulp, which comprises water and plant-based fibers, particularly cellulosic fibers. In these compositions, the mineral matter is in the form of particles. The use of such mineral fillers makes it possible, in particular, to improve the physical properties of the paper, especially its optical properties, or to reduce the relative quantity of cellulosic material compared to the quantity of mineral filler, or to improve the optical properties of coated paper.

[0009] The improvement of the efficiency of paper manufacturing processes is also made possible through the use of these mineral fillers.

[0010] In order to improve the use of these mineral filler compositions in papermaking, more particularly to retain these mineral fillers in the During the papermaking process, it is known to use cationic compounds, particularly cationic starches or cationic acrylamide copolymers, to retain the fibrous mat of the paper sheet. These cationic compounds, or cationic mineral filler-retaining agents, increase the retention of mineral fillers on plant fibers or fibrils during papermaking. Specifically, by neutralizing the charges carried by the mineral filler particles, these cationic retention agents allow the formation of cationic coagulates retained by the plant fibers or fibrils. These cationic compounds also improve the dewatering phase during papermaking, during which the greatest possible amount of mineral filler must be retained in the fibrous mat of the paper sheet.These cationic compounds also help to limit the loss of cellulosic material in the form of fine particles. Thus, cationic compounds are commonly used in papermaking, including cationic agents such as cationic flocculants, cationic coagulants, or cationic agents for retaining mineral or cellulosic material.

[0011] The reduction of the absolute value of the "Mütek" charge or of the cationic demand of a composition of mineral matter particles in water must also be sought.

[0012] The cationic demand can be determined using a device for measuring the flow current of the mineral filler composition (DC current detector or streaming current detector). This flow current measurement can be carried out using a "Mütek" apparatus by pouring polyDADMAC until the electrical charges of the mineral filler composition are neutralized. A value for the "Mütek" charge of the mineral filler composition is then obtained.

[0013] Thus, although methods exist for preparing concentrated aqueous compositions of mineral matter that employ polymers as concentration or dispersion aids, prior art methods do not always provide satisfactory solutions to the problems encountered. Therefore, there is a need for improved methods for preparing concentrated aqueous compositions of mineral matter. The invention provides a solution to all or part of the problems of prior art methods.

[0014] Thus, the invention provides a method for preparing an aqueous composition C of mineral particles, in the presence of at least one water-soluble polymer P, having a molecular mass Mw, measured by CES, ranging from 1,500 g / mol to 50,000 g / mol, and prepared by a radical polymerization reaction in water, of at least one compound Ml selected from itaconic anhydride, itaconic acid, sodium itaconate, potassium itaconate, lithium itaconate, ammonium itaconate, calcium itaconate, magnesium itaconate and their combinations, comprising: A- the grinding in water of an aqueous composition Cd comprising at least one particulate mineral material M in a concentration ranging from 15% by weight to 60% by weight of the composition Cd resulting in a composition Cb, then B1- the mechanical concentration of the aqueous composition Cb in the absence of polymer P resulting in the composition Ce followed by its dispersion in the presence of polymer P or its thermal concentration in the presence of polymer P, or B2- the thermal concentration of the composition Cb in the presence of polymer P.

[0015] Before being concentrated, the composition according to the invention includes the essential step A of grinding the mineral matter M in a wet medium.

[0016] During grinding, the starting composition Cd has a mineral matter concentration M ranging from 15% by weight to 60% by weight. Preferably according to the invention, the concentration of composition Cd is greater than 20% by weight, preferably greater than 25% by weight of composition Cd. Also preferably according to the invention, the concentration of composition Cd is less than 55% by weight, preferably the concentration of composition Cd ranges from 15% by weight to 50% by weight or from 20% by weight to 55% by weight of composition Cd.

[0017] According to the invention, the grinding can be carried out in the presence of a grinding aid. Generally, this is a polycarboxylic acid, in particular a (meth)acrylic polymer. Preferably for the method according to the invention, the aqueous composition Cd is ground in the absence of a grinding aid, preferably in the absence of a polycarboxylic acid, in particular in the absence of a (meth)acrylic polymer or in the absence of polyitaconic acid or in the absence of polymer P.

[0018] For the preparation method according to the invention, the aqueous composition Cb from the grinding step A can therefore have a concentration of particulate mineral matter M ranging from 15% by weight to 60% by weight, preferably a concentration ranging from 15% by weight to 30% by weight or a concentration ranging from more than 30% by weight to 60% by weight.

[0019] Also preferably, the aqueous composition Cb from the grinding step A, the concentration of particulate mineral matter M of which ranges from 15% by weight to 30% by weight, can be obtained by grinding in the absence of a grinding aid.

[0020] Also preferably, the aqueous composition Cb from the grinding step A, the concentration of particulate mineral matter M of which ranges from more than 30% by weight to 60% by weight, can be obtained by grinding in the presence of an agent grinding aid, preferably in the absence of polycarboxylic acid, in particular a (meth)acrylic polymer or a polyitaconic acid or the P polymer.

[0021] Essentially, according to the invention, the aqueous composition of ground mineral matter Cb is treated to remove some of the water it contains. The concentration of the composition Cb then increases its concentration of mineral matter M.

[0022] In step B1, composition Cb is mechanically concentrated to obtain the more concentrated composition Ce, which can be dispersed in the presence of polymer P to form composition C according to the invention. According to the invention, composition Ce can subsequently be thermally concentrated in the presence of polymer P to form composition C according to the invention.

[0023] During step B2, composition Cb is treated by thermal concentration in the presence of polymer P to form composition C according to the invention.

[0024] Thus, the aqueous composition Ce has a concentration of particulate mineral matter M which is greater than the concentration of the composition Cb. Preferably according to the invention, the aqueous composition Ce has a concentration of particulate mineral matter M ranging from 35% by weight to 65% by weight, preferably ranging from 40% by weight to 65% by weight or from 50% by weight to 65% by weight.

[0025] Finally, the aqueous composition C generally has a concentration of particulate mineral matter M which is greater than the concentration of the composition Ce. Preferably, the composition C has a concentration ranging from 40% by weight to 72% by weight, preferably ranging from 40% by weight to 76% by weight, more preferably ranging from 40% by weight to 78% by weight.

[0026] According to the invention, the thermal concentration B2 is carried out in the presence of the polymer P. It can also be carried out in the presence of phosphoric acid, in particular in an amount of phosphoric acid ranging from 0.05% to 1% by dry weight of phosphoric acid relative to the dry weight of mineral matter M.

[0027] According to the invention, phosphoric acid can be implemented separately, simultaneously or in combination with polymer P, preferably in an amount from 0.05% to 1%, preferably from 0.1% to 0.6%, in dry weight of phosphoric acid relative to the dry weight of mineral matter M.

[0028] According to the invention, it is also possible that phosphoric acid is not used at all.

[0029] The invention allows for the preparation of an aqueous composition C of mineral particles by grinding a composition Cd of particulate mineral matter M in water. Generally, according to the invention, the mineral matter M used is not soluble in water at room temperature. Preferably, for the method according to the invention, a single material M, or two or three materials M, are used.

[0030] According to the invention, the mineral material M can be synthetic or of natural origin. Preferably, it is selected from alkaline earth metal carbonates, preferably calcium carbonate (natural calcium carbonate or precipitated calcium carbonate), strontium carbonate, magnesium carbonate, barium carbonate, dolomite, kaolin, titanium dioxide, talc, lime, magnesium hydroxide, calcium sulfate, and barium sulfate. Calcium carbonate and kaolin are particularly preferred.

[0031] According to the invention, the crushed mineral material particles M have a median size, measured by sedimentation analysis, of less than 50 pm, or a median size ranging from 0.05 pm to 50 pm, or a median size of less than 10 pm. Preferably, this size is less than 5 pm or 2 pm, more preferably less than 1 pm or less than 0.5 pm.

[0032] Essentially according to the invention, the method for preparing composition C uses at least one polymer P during at least one thermal concentration or dispersion step.

[0033] Preferably, for the preparation method according to the invention, the polymer P has a molecular mass Mw, measured by CES, ranging from 2,000 g / mol to 50,000 g / mol or from 1,500 g / mol to 40,000 g / mol. Preferably, the molecular mass Mw of the polymer P ranges from 2,000 g / mol to 25,000 g / mol or from 1,500 g / mol to 20,000 g / mol. More preferably, it ranges from 2,000 g / mol to 20,000 g / mol, even more preferably from 2,000 g / mol to 15,000 g / mol, much more preferably from 3,000 g / mol to 13,000 g / mol or from 2,500 g / mol to 15,000 g / mol, particularly preferentially from 3,500 g / mol to 20,000 g / mol or from 3,000 g / mol to 15,000 g / mol, very preferably from 3,500 g / mol to 15,000 g / mol and much more preferably from 3,500 g / mol to 13,000 g / mol.

[0034] Also preferably for the preparation method according to the invention, the polymer P has a polymolecularity index IP, measured by CES, of less than 5.5, preferably less than 4.5. More preferably, the polymolecularity index IP is less than 4. Also more preferably, this polymolecularity index IP, measured by CES, ranges from 1.6 to 5.5, preferably from 1.6 to 4.5, more preferably from 1.6 to 4.

[0035] According to the invention, the molecular weight or mass of polymer P is determined by Size Exclusion Chromatography (SEC). A test portion of the polymer solution, 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, NaN3: 0.03 wt%. The SEC system consists of a Waters 510 isocratic pump, the flow rate of which is The system is set at 0.8 mL / min and consists of a Waters 717+ autosampler, an oven 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 oven is heated to 60°C and the refractometer to 45°C. The CES system is calibrated with a series of sodium polyacrylate standards supplied by Polymer Standard Service, with peak molecular weights ranging from 1200 g / mol to 1390,000 g / mol and polymolecularity indices ranging from 1.4 to 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 performed using the software "NTeqGPC" v.5.1.5". The resulting chromatogram is integrated into the area corresponding to molecular weights greater than 250 g / mol.

[0036] According to the invention, the polymer P is prepared by a radical polymerization reaction of the compound Ml selected from itaconic anhydride, itaconic acid, sodium itaconate, potassium itaconate, lithium itaconate, ammonium itaconate, calcium itaconate, magnesium itaconate and their combinations.

[0037] Preferably, the polymerization reaction involves a combination of itaconic acid and at least one itaconate, preferably an itaconate selected from sodium itaconate, potassium itaconate, lithium itaconate, ammonium itaconate.

[0038] Preferably according to the invention, the polymer P is totally or partially neutralized, preferably by means of an ion chosen from a monovalent ion, a divalent ion and their combinations, more preferably by means of an ion chosen from K+, Na+, Li+, NH4+, Mg2+, Ca2+ and their combinations.

[0039] Also preferably, the polymer P is totally or partially neutralized by means of at least one compound selected from LiOH, NaOH, KOH, Zn(OH)2, Mg(OH)2, Ca(OH)2, ZnO, MgO, CaO, ammonium derivatives, ammonia, ammonia, amino bases, for example triethanolamine, aminomethylpropanol, diethanolisopropylamine or 2-amino-2-methylpropanol (AMP) and their combinations, more preferably NaOH, Ca(OH)2, CaO and their combinations.

[0040] According to the invention, the polymer P is prepared by a radical polymerization reaction in water of at least one compound ML. Preferably for the method according to the invention, the polymerization reaction involves a combination of itaconic acid and an itaconate, preferably a combination of itaconic acid and an itaconate selected from sodium itaconate, itaconate of potassium, lithium itaconate, ammonium itaconate. Also preferably, the polymerization reaction involves a combination of itaconic acid and an itaconate in a molar ratio of an itaconic acid / itaconate combination ranging from 80 / 20 to 20 / 80, more preferably ranging from 45 / 55 to 55 / 45.

[0041] Preferably according to the invention, compound Ml does not comprise an ester group, in particular compound Ml is not an ester of itaconic acid, in particular an itaconic acid diester.

[0042] Besides compound Ml, polymer P can also be prepared using at least one other compound different from compound Ml, preferably from 0.5% by weight to 30% by weight of another compound relative to the total amount by weight of monomers.

[0043] Thus, polymer P can also be prepared using another compound selected from: * a compound M2 selected from acrylic acid, methacrylic acid, an acrylic acid oligomer, a methacrylic acid oligomer, an acrylic acid salt, a methacrylic acid salt, an acrylic acid oligomer salt, a methacrylic acid oligomer salt, maleic acid, maleic anhydride, crotonic acid, 2-acrylamido-2-methylpropane sulfonic acid, a salt of 2-acrylamido-2-methylpropane sulfonic acid, ethoxymethacrylate sulfonic acid, sodium methallyl sulfonate, styrene sulfonate, phosphated hydroxyethyl acrylate, phosphated hydroxyethyl methacrylate, phosphated hydroxypropyl acrylate, phosphated hydroxypropyl methacrylate, phosphated hydroxybutyl acrylate, phosphated hydroxybutyl methacrylate and their combinations; * a compound M3 independently selected from CrCi2 esters of methacrylic acid, C1-C12 esters of acrylic acid, acrylamide, N-tert-butylacrylamide, alkylacrylamides, N-methylolacrylamide, acrylonitrile, vinyl-lactam, N-vinylpyrrolidone, ureidomethacrylate, hydroxyethylacrylate, hydroxyethylmethacrylate, hydroxypropylacrylate, hydroxypropylmethacrylate, hydroxybutylmethacrylate, hydroxybutylacrylate, caprolactone methacrylate, caprolactone acrylate, polycaprolactone methacrylate, polycaprolactone acrylate, lactame methacrylate, lactame acrylate, polycaprolactame methacrylate, polycaprolactame acrylate, vinyl acetate and combinations thereof; preferably CrC8 esters of methacrylic acid, Ci-C8 esters of acrylic acid and their combinations;preferably, Nt ert-butylacrylamide, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, more preferably, methyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate and their combinations. ;

[0044] For the method according to the invention, the polymerization reaction is carried out in the presence of an initiating compound 1, preferably an initiating compound selected from a peroxide (for example hydrogen peroxide, tert-butyl hydroperoxide), a persalt, preferably a persulfate (for example sodium persulfate, ammonium persulfate, potassium persulfate), their combinations and their associations with optionally a metallic salt, preferably a metallic salt selected from an iron salt (for example Fe11 or Fe111), a copper salt (for example Cu1 or Cu11) and their combinations.

[0045] The polymerization reaction can also be carried out in the presence of at least one sulfur compound Tl comprising sulfur in oxidation state IV (sulfur IV or SIV). Preferably, compound Tl is selected from lithium hydrogen sulfite, sodium hydrogen sulfite, potassium hydrogen sulfite, ammonium hydrogen sulfite, calcium di(hydrogen sulfite), magnesium di(hydrogen sulfite), and combinations thereof. Preferably, compound Tl is used in an amount of 0.5% to 15% by weight, preferably 1% to 10% by weight, and more preferably 1.5% to 8% by weight, relative to the total dry weight of monomers used in the polymerization reaction.

[0046] The polymerization reaction can also be carried out in the presence of at least one phosphorus compound T2 comprising phosphorus in oxidation state I (phosphorus I or P1) or comprising phosphorus in oxidation state III (phosphorus III or P1u). Preferably, compound T2 is selected from hypophosphorous acid, sodium hypophosphite, ammonium hypophosphite, phosphorous acid, sodium phosphite, and ammonium phosphite. Preferably, compound T2 is used in an amount of 0.5% to 15% by weight, preferably 1% to 10% by weight, and more preferably 1.5% to 8% by weight, relative to the total dry weight of monomers used in the polymerization reaction.

[0047] During the polymerization reaction, the reaction conditions may vary. Preferably, compound Ml is present during the polymerization reaction in an amount by weight greater than 30%, preferably greater than 35% or 40%, more preferably greater than 45% or 50%, relative to all the compounds present in the reaction medium.

[0048] Preferably according to the invention, the polymerization reaction comprises: * the preparation of a reaction medium comprising at least one compound Ml in a quantity by weight greater than 35%, preferably greater than 50% or 60%, plus preferably greater than 65% or 70%, relative to all the reactants in this reaction medium, then * the addition of the initiating compound, possibly separate addition of compound Tl or possibly of compound T2, and possibly separate addition of compound Ml and * heating of the reaction medium.

[0049] Essentially, the method of preparing composition C according to the invention uses polymer P. For this preparation method, the quantity of polymer P can vary but it preferably ranges from 0.05% to 5% by dry weight, preferably from 0.3% to 2.0% by dry weight, relative to the dry weight of particulate mineral matter M.

[0050] Preferably according to the invention, the thermal concentration is achieved by heating, preferably at a heating temperature above 80°C or at a heating temperature below 95°C.

[0051] Also preferably according to the invention, the mechanical concentration is carried out by centrifugation or by means of a filter press or a rotary filter.

[0052] The preparation method according to the invention makes it possible to obtain a composition C highly concentrated in mineral matter M. Preferably according to the invention, the concentration of composition C in mineral matter M is greater than 60% by weight or greater than 65% by weight or greater than 70% by weight or is less than 78% by weight or is less than 75% by weight, preferably from 70% by weight to 78% by weight or from 70% by weight to 75% by weight of composition C.

[0053] The polymer P implemented according to the invention favorably influences the properties of the composition C according to the invention when used according to the preparation method of the invention. In particular, the polymer P according to the invention makes it possible to control the viscosity of the composition C. Preferably according to the invention, the Brookfield viscosity of the composition C measured at 25°C, at 100 rpm 1 hour after preparation, can be less than 800 mPa·s, preferably less than 600 mPa·s, more preferably less than 400 mPa·s.

[0054] Also preferably according to the invention, the Brookfield viscosity of composition C measured at 25°C, at 100 rpm before stirring, measured 8 days after preparation can be less than 2,500 mPa.s, preferably less than 2,000 mPa.s, more preferably less than 1,500 mPa.s or 1,000 mPa.s, much more preferably less than 800 mPa.s.

[0055] The interaction of polymer P with mineral matter M also makes it possible to limit the amount of free polymer in composition C according to the invention. Preferably, the amount of free polymer P not adsorbed onto mineral matter M, measured by determining the amount of total organic carbon by weight present in the water of composition C, is less than 45% by weight, preferably less than 35% by weight, relative to the total amount of organic carbon of polymer P introduced during concentration.

[0056] Also, the implementation of polymer P during the preparation of composition C according to the invention makes it possible to control the cationic demand of composition C. Preferably according to the invention, the cationic demand of composition C measured using a "Mütek" device is less in absolute value than -25 peq / g of composition C.

[0057] The use of polymer P during the preparation of composition C according to the invention makes it possible to prepare a concentrated aqueous composition C possessing properties useful in many technical fields. Thus, the invention also provides an aqueous composition C obtained according to the preparation method of the invention.

[0058] The polymer P according to the invention can be used directly or it can be combined with water. Thus, the invention provides an aqueous agent D with a concentration of composition Cb according to the invention comprising at least one polymer P defined according to the invention.

[0059] Polymer P imparts particular properties to composition C according to the invention and allows its use in combination with other mineral material compositions having different characteristics or obtained by preparation methods different from the method for preparing composition C according to the invention. Thus, the invention also provides a method for preparing an aqueous composition Cm of mineral particles comprising: i. the preparation of an aqueous composition C according to the invention; ii. the preparation of an aqueous composition Cg comprising a mineral material Q in a concentration ranging from 65% by weight to 78% by weight of the composition Cg, and obtained by grinding in water a mineral material Q in the presence of a grinding aid, preferably a (meth)acrylic polymer R; iii. the mixing under stirring of the aqueous composition C with the aqueous composition Cg.

[0060] Preferably according to the invention, the composition Cg is prepared by a method which includes grinding in water, at a high concentration of mineral matter Q and in the presence of a grinding aid comprising at least one polymer R. Preferably, the polymer R is generally a polyacrylate, for example a sodium polyacrylate or a sodium and calcium polyacrylate.

[0061] Very advantageously, the presence of polymer P in composition C mixed with composition Cg improves the compatibility of composition C with composition Cg to obtain composition Cm according to the invention.

[0062] According to the invention, the mineral material Q can be synthetic or of natural origin. Preferably, it is selected from alkaline earth metal carbonates, preferably calcium carbonate (natural calcium carbonate or precipitated calcium carbonate), strontium carbonate, magnesium carbonate, barium carbonate, dolomite, kaolin, titanium dioxide, talc, lime, magnesium hydroxide, calcium sulfate, and barium sulfate. Calcium carbonate and kaolin are particularly preferred.

[0063] Preferably according to the invention, the method of preparing composition Cm makes it possible to obtain a composition Cm which comprises from 60% to 90% by dry weight of composition C and from 10% to 40% by dry weight of composition Cg, relative to the dry weight of composition Cm.

[0064] Also preferably according to the invention, the concentration of the composition Cm in mineral matter M and Q is greater than 45% by weight or 50% by weight or 70% by weight or is less than 78% by weight or is less than 75% by weight, preferably goes from 70% by weight to 78% by weight or from 70% by weight to 75% by weight of the composition Cm.

[0065] Preferably, the Brookfield viscosity of the composition Cm measured at 25°C, at 100 rpm 1 hour after preparation, is less than 800 mPa.s, preferably less than 600 mPa.s.

[0066] Preferably, the Brookfield viscosity of the composition Cm measured at 25°C, at 100 rpm before stirring, measured 8 days after preparation is less than 2,500 mPa.s, preferably less than 2,000 mPa.s, more preferably less than 2,000 mPa.s or 1,000 mPa.s.

[0067] The invention therefore also provides an aqueous composition Cm obtained according to the preparation method of the invention. According to the invention, the use of polymer P allows for good control of the rheology of the composition Cm according to the invention. Thus, the invention provides a method for controlling the viscosity of a composition Cm according to the invention, comprising the use of at least one polymer P according to the invention or of an aqueous concentrating or dispersing agent according to the invention.

[0068] The use of compositions C and Cm according to the invention for the manufacture of paper is particularly advantageous, in particular for the preparation of a paper mass filler composition or for the preparation of a paper coating sauce composition.

[0069] Thus, the invention provides an aqueous papermaking preparation composition selected from a papermaking bulk filler composition and a papermaking coating slurry composition comprising: - a composition C according to the invention or a composition Cm according to the invention and possibly - at least one binding compound, and possibly at least one compound selected from a rheology modifier compound, a water-retaining agent and an optical brightening agent.

[0070] According to the invention, the paper mass filler composition and the paper coating sauce composition are prepared by mixing their different ingredients, in particular by mixing these ingredients in water.

[0071] The invention also provides a method of paper preparation comprising the application of a composition C according to the invention or a composition Cm according to the invention.

[0072] According to the invention, the particular, advantageous or preferred characteristics of composition C according to the invention and of its method of preparation define methods for its use, compositions Cm and paper preparation compositions, methods for their preparation or using them as well as concentrating agents according to the invention which are also particular, advantageous or preferred.

[0073] The various aspects of the invention can be illustrated by the following examples. The methods or techniques implemented are known or described. EXAMPLES

[0074] Preparation and characterization of polymers P according to the invention Preparation of the PI polymer according to the invention

[0075] In a glass reactor, 207 g of itaconic acid (compound Ml) are introduced, and 127.38 g of a 50 wt% aqueous sodium hydroxide solution are added. The reaction is exothermic, the reactor temperature is maintained at 90°C ± 2°C, and then 21 g of deionized water are introduced.

[0076] In a first beaker, 10.3 g of sodium persulfate and 21 g of deionized water are weighed.

[0077] The reagents from the beaker are introduced all at once into the reactor, and the temperature is maintained at 90°C ± 2°C for 2 hours. Then, 150 g of deionized water is added, and the mixture is allowed to cool to room temperature. The PI polymer solution is neutralized to pH 7.4 by adding 50 wt% sodium hydroxide to the water. The resulting composition, CPI, comprises the PI polymer according to the invention at 47.0 wt% dry extract, the composition and characteristics of which are detailed in Table 1. Preparation of polymer P2 according to the invention

[0078] In a glass reactor, 207 g of itaconic acid (compound Ml) are introduced, and 127.38 g of a 50 wt% aqueous sodium hydroxide solution in water are added. The reaction is exothermic, the reactor temperature is maintained at 90°C ± 2°C, then 0.008 g of iron sulfate heptahydrate diluted in 10 g of deionized water is introduced at once.

[0079] In a first beaker, 27.3 g of hydrogen peroxide in a 35 wt% solution and 27 g of deionized water are weighed out. In a second beaker, 25 g of sodium bisulfite in a 40 wt% aqueous solution are weighed out.

[0080] The reactants from the two beakers are introduced in parallel into the reactor for 2 hours and the temperature is maintained at 90°C ± 2°C for 1 hour. Then, 150 g of deionized water is added and the mixture is allowed to cool to room temperature.

[0081] The polymer P2 solution is neutralized to pH = 7.9 by adding 50 wt% sodium hydroxide to water. This yields composition CP2, comprising polymer P2 according to the invention at 44.4 wt% dry extract, the composition and characteristics of which are detailed in Table 1.

[0082] [tab 1] Polymer PI. P2 Mw (g / mol) 6715 7415 IP 3.1 3.3 pH 7.4 79 ES (H) 47.0 Charge (C / g dry polymer) -810 -820

[0083] Measurement of the charge of polymer P according to the invention

[0084] Approximately 1 g dry of neutralized polymer is introduced into a 1 L volumetric flask. The mass mO in grams of polymer P of dry extract ESp is precisely recorded. Deoxygenated water is added to dilute the polymer, and the volume is adjusted to the calibration mark with deoxygenated water. The volumetric flask is thoroughly shaken to obtain a homogeneous solution. Approximately 0.5 g of the previously prepared neutralized polymer solution is introduced into the measuring cell of a Mütek PCD 03 instrument equipped with an automatic titrator PCD titrator two using a pre-calibrated micropipette. The mass ml in grams is precisely recorded. Approximately 20 mL of deoxygenated water is also introduced into this measuring cell. The piston of the measuring cell is activated for approximately 1 minute before starting the actual titration.The titration is then automatically initiated by introducing a titrant solution into the measuring cell. This solution is a polyDADMAC (poly(diallyldimethyl ammonium chloride)) solution with molecular weights ranging from 10,000 to 400,000 g / mol. A certified solution of this polymer titrant at a concentration of 0.001 N is commercially available. In our case, it is supplied by the company "NOVIPROFIBRE" (France). The titration stops when the charge neutralization point is reached. The volume of titrant solution dispensed, V, is then recorded in mL. The polymer charge is given by the following expression: charge = -96,485 X F 10 x mu x ESP x ml

[0085] This charge of the polymer is expressed in Coulombs per gram of dry polymer.

[0086] Preparation and characterization of aqueous compositions C according to the invention

[0087] An aqueous composition Cdl comprising calcium carbonate (Carrara marble “Omyacarb” 10 AV) is ground in water using a horizontal mill “DYNO” - MILL Type KDL-Pilot A (“WAB-Group”, Switzerland) to a concentration of 18 wt%. The resulting aqueous composition Cbl consists of 75 wt% of the calcium carbonate particle population having an equivalent spherical diameter of less than 1 µm. The Cbl composition is mechanically concentrated by centrifugation using a centrifuge to obtain the Ccl composition, which has a concentration of 55 wt% of mineral matter M.

[0088] Then, at room temperature and with stirring, 2800 g of composition Ccl and composition CPI, providing 0.60 g of dry PI polymer per 100 g of dry calcium carbonate, are mixed in the bowl of a mixer (“Vorwerk”). Composition Ccl is thermally concentrated by heating to 90°C while adding, every 30 minutes, composition CPI, providing 3 x 0.45 g of dry PI polymer per 100 g of dry calcium carbonate.

[0089] The composition Cl according to the invention is obtained, the concentration of which is 72.0% by dry weight of mineral matter M.

[0090] Similarly, by replacing the CPI composition comprising the PI polymer with the CP2 composition comprising the P2 polymer, the C2 composition according to the invention is prepared, the concentration of which is 71.7% by dry weight of mineral matter M.

[0091] After cooling to room temperature, the Cl and C2 compositions are characterized by measurements of pH, dry extract (DE), free polymer content (P), calcium carbonate particle size, viscosity, and Mütek charge. The stability of the Cl and C2 compositions is also evaluated. The results are presented in Table 2.

[0092] Measurement of the free polymer content in Cl and C2 compositions

[0093] For a diluted CPI composition comprising the PI polymer at a concentration in water of PI polymer by dry weight identical to that of the Cl composition, the TOC1 (Total Organic Carbon) value is determined by measuring the quantity of organic carbon using an Xpert-COT / TNb TOC analyzer “HACH”.

[0094] Then, after separation by filtration of the calcium carbonate from composition Cl, the TOC2 value is determined by measuring the amount of organic carbon in the filtrate of composition CL

[0095] The amount of free PI polymer in composition Cl is calculated according to the equation: TOC2% free dispersant = -----x 100; T0C1

[0096] In a similar way, the amount of free polymer P2 in composition C2 is determined. Particle size measurement of Cl and C2 compositions

[0097] The particle size distribution of calcium carbonate particles of compositions Cl and C2 is measured using a particle size analyzer (“Sedigraph” 5100 “Micromeritics”) by determining the value of the mass percentage of the population of particles whose equivalent spherical diameter is less than 1 pm (esd < 1 pm).

[0098] These measurements are carried out using Cl and C2 compositions dispersed at a concentration of 33 g of dry matter per liter in a solution of sodium polyacrylate with a molecular weight of 4000 g / mol and a concentration of 1.6 g of dry sodium polyacrylate per liter of solution. Each sample is subjected to ultrasound before measurement.

[0099] Measurement of Brookfield γ-isososity and stability of Cl and C2 compositions

[0100] One hour after their preparation, the Brookfield viscosity (VB0 - in mPa.s) of The composition of Cl and C2 according to the invention is measured at 25°C ± 1°C and at a rotation speed of 100 rpm using a Brookfield DVIII viscometer equipped with a module 2 to 5 adapted to the specific viscosity. After 8 days in a climate-controlled chamber at 25°C, and in a similar manner, the Brookfield viscosity (VB8 - in mPa·s) of the Cl and C2 compositions is measured.

[0101] Measurement of the cationic demand (Mütek charge) of the Cl and C2 compositions

[0102] The cationic demand of the Cl and C2 compositions is measured using a titrator (“Mütek” PCD 03) equipped with an automatic titrator PCD titrator two, by titration using a cationic polymer of known titer and until neutralization of the charges contained in the sample of each of the Cl and C2 compositions.

[0103] The titrant solution is a 0.001 N solution of polyDADMAC (poly(diallyldimethyl ammonium chloride) from "NOVIPROFIBRE" (France)) with molecular masses between 10,000 g / mol and 400,000 g / mol.

[0104] 0.8 g of composition Cl or C2 is weighed out and 20 mL of diperized water is added. The piston is placed in the cell and the motor driving the piston's reciprocating motion is started. After 2 to 3 minutes, the titration begins. At the end of the titration, the instrument provides the measurement result (in peq / g of composition).

[0105] [tab 2] Composition Cl C2 Polymer Pi P2 ES (¾ by weight) 72.0 71.7 pH 9.2 9.4 Free dispersant (%) 30.6 27.3 Cationic demand (peq / g) -25.1 -2 L0 VBO (mPa.s) 247 72^ VB8 (mPa.s) 628 603

[0106] The PI and P2 polymers allow the preparation of highly concentrated Cl and C2 compositions with well-controlled viscosity. These compositions are stable, contain very little free polymer, and exhibit low cation demand.

[0107] Preparation and characterization of C m compositions according to the invention

[0108] Compositions Cml and Cm2 are prepared respectively by mixing compositions Cl and C2 with an aqueous composition Cgi comprising calcium carbonate ground in water at a high concentration (74.6 wt.) in the presence of a grinding aid (poly(acrylic acid) partially neutralized with sodium -Mw of 4700 g / mol) and of which 82.8 wt. of the particles have an equivalent spherical diameter of less than 1 pm. Composition Cgi has a dry extract of 74.6 wt., a pH of 9.4 and a Brookfield viscosity measured at 100 rpm at 25°C of 188 mPa·s.

[0109] The composition Cg is mixed, under mechanical stirring for approximately 20 minutes, in a weight ratio of 20 / 80 sec / sec with the compositions Cl and C2, respectively. The resulting compositions Cml and Cm2 according to the invention are characterized in the same way as the compositions Cl and C2 according to the invention. The results are presented in Table 3.

[0110] [tab 3] Composition Cm Cml Cm2 Composition C Cl C2 Polymer PI P7 ES (%) 73.0 72.2 pH 9.2 9.3 VBÛ (mPa.s) 323 257 VB8 (mPa.s) §98 822

[0111] The PI and P2 polymers allow the preparation of highly concentrated and stable compositions Cml and Cm2. The Cl and C2 compositions according to the invention exhibit very good compatibility with the known aqueous composition of calcium carbonate Cgi.

[0112] Preparation and characterization of an aqueous composition of bread preparation according to the invention

[0113] The mixture is stirred using a "VMI Turbotest" dispersion apparatus: - 100 parts by mass of composition C2 according to the invention, - 9 parts of a binding compound (DL1066 "Trinseo") at 55% by weight in water, - 0.4 part of polyvinyl alcohol (“Mowiol” 5-98 “Chang Chung Petrochemical”) at 25% by weight in water, - 0.6 part of an optical brightening compound (“Blankophor” TP 4900 “Indulor”), - 0.135 part of a thickening compound (“Rheocoat” 93 “Coatex”) at 31% by weight in water, - water qsp for a dry extract of 69% by mass.

[0114] The pH of the aqueous composition of paper preparation according to the invention is adjusted to 8.8 by adding sodium hydroxide in aqueous solution at 20% by weight.

[0115] The dry extract of the composition obtained is measured using a microwave balance (MMB) by depositing between 1 g and 4 g of the composition onto a piece of fiberglass paper having a determined mass. The balance then dries the composition by microwave irradiation until its weight remains constant for 10 seconds. The weight loss allows the dry extract (% by weight) of the paper preparation composition according to the invention to be determined.

[0116] The pH is measured at 25°C using a pH meter (WTW) equipped with a conventional electrode coupled to a temperature probe. The Brookfield viscosity (in rnPa.s) of the paper preparation composition according to the invention is measured at 100 rpm and 25°C using an analog viscometer rheometer equipped with a spindle adapted to the viscosity range of the composition.

[0117] The capillary viscosity (in rnPa.s) of the paper preparation composition according to the invention is measured at high shear gradient (500,000 s*) and at 25°C using a capillary viscometer (AX100 ACA) equipped with a capillary 10 mm long and 0.5 mm in inner diameter.

[0118] The water retention of the papermaking composition according to the invention is determined by means of a water retention measuring apparatus (AAGWR “Gradek”) comprising a measuring chamber in which a test paper (Test Blotter Paper “Gradek”) covered by a perforated plastic film (Test Filter PCTE “Gradek” - 2 µm) is placed. 10 mL of the papermaking composition according to the invention is introduced into the chamber. A pressure (1.5 bar for 90 seconds) is applied to the composition, causing all or part of the water and water-soluble substances to pass through the perforated plastic film and migrate into the test paper.

[0119] The increase in paper mass (between pO weighed before measurement and pl weighed at the end of measurement) corresponds to the quantity of water and water-soluble substances that migrated from the papermaking composition according to the invention to the test paper during the measurement. The relative value of the increase in water retention is equal to 1250 x (pl - pO) / pO.

[0120] The results are presented in Table 4.

[0121] [tab 4] Brookfield viscosity (mPa.s) 1390 AX100 viscosity (mPa.s) 41 AA-GWR water retention (g / in²) 151

[0122] The polymers according to the invention make it possible to prepare papermaking compositions which are stable and whose viscosity and water retention are well controlled.

[0123] Preparation and characterization of paper according to the invention

[0124] A sheet of wood-free paper measuring 21 x 29.7 cm with a specific weight of 78 g / m² is used. This sheet is coated with the coating solution to be tested using a laboratory coating machine with a scraper blade. Each sheet of paper is coated at 11-12 g / m² and dried in a non-ventilated oven for 5 minutes at 50°C. Each sheet is then calendered on both sides using a laboratory calender at 80°C and 25 bar.

[0125] The optical properties of the coated paper were measured using a spectrophotometer (“Elrepho” 3000 “Data Color”): - Whiteness W(CIE) according to ISO 11475 standard, - Opacity according to standard NFQ-03040, - reflectance in the blue (wavelength equal to 457 nm) according to the TAPPI T 452 om-08 standard, ISO 2470, - opacity according to standard TAPPI T 519 om-06, ISO 2471.

[0126] Gloss is measured according to TAPPI T 480 om-09 using a glossmeter (dimension: m / "Lehmann"). Contact angles were measured with bi-permuted water and rapeseed oil using a contact angle goniometer ("Digidrop" OCE 15EC "DataPhysics").

[0127] The results are presented in Table 5.

[0128] [tab 5] Reflectance at 457 nm 105 Whiteness W(C1E) 135 Opacity 96 Gloss at 75° 70 Water contact angle (°) ss Oil contact angle O 20

[0129] The P polymers according to the invention make it possible to prepare coated paper having very good optical properties.

Claims

Demands

1. Method of preparing an aqueous composition C of mineral particles, in the presence of at least one water-soluble polymer P, having a molecular mass Mw, measured by CES, ranging from 1,500 g / mol to 50,000 g / mol, and prepared by a radical polymerization reaction in water, of at least one compound Ml selected from itaconic anhydride, itaconic acid, sodium itaconate, potassium itaconate, lithium itaconate, ammonium itaconate, calcium itaconate, magnesium itaconate and their combinations, comprising: A- the grinding in water of an aqueous composition Cd comprising at least one particulate mineral material M in a concentration ranging from 15 wt% to 60 wt% of the composition Cd resulting in a composition Cb,then B1- the mechanical concentration of the aqueous composition Cb in the absence of polymer P resulting in the composition Ce followed by its dispersion in the presence of polymer P or its thermal concentration in the presence of polymer P, or B2- the thermal concentration of the composition Cb in the presence of polymer P.

2. Method according to claim 1 wherein: - the aqueous composition Cd is ground in the absence of a grinding aid, preferably in the absence of polycarboxylic acid, in particular in the absence of (meth)acrylic polymer or in the absence of polyitaconic acid or in the absence of polymer P; or - the thermal concentration B2 is carried out in the presence of phosphoric acid, preferably in an amount from 0.05% to 1% by dry weight of phosphoric acid relative to the dry weight of mineral matter M; or - the phosphoric acid is used separately, simultaneously or in combination with the polymer P, preferably in an amount from 0.05% to 1%, preferably from 0.1% to 0.6%, by dry weight of phosphoric acid relative to the dry weight of mineral matter M, or no phosphoric acid is used.

3. A method according to claim 1 or 2 wherein: - the concentration of the Cd composition is greater than 20% by weight, preferably greater than 25% by weight of the Cd composition; or - the concentration of the Cd composition is less than 55% by weight, preferably the concentration of the Cd composition ranges from 15% by weight to 50% by weight or from 20% by weight to 55% by weight of the Cd composition;or for which: - the aqueous composition Cb has a concentration of particulate mineral matter M ranging from 15% by weight to 60% by weight, preferably a concentration ranging from 15% by weight to 30% by weight or a concentration ranging from more than 30% by weight to 60% by weight, or - the aqueous composition Ce has a concentration of particulate mineral matter M which is greater than the concentration of composition Cb or the aqueous composition Ce has a concentration of particulate mineral matter M ranging from 35% by weight to 65% by weight, preferably ranging from 40% by weight to 65% by weight or from 50% by weight to 65% by weight, or - the aqueous composition C has a concentration of particulate mineral matter M which is greater than the concentration of composition Ce or composition C has a concentration ranging from 40% by weight to 72% by weight, preferably ranging from 40% by weight to 76% by weight, more preferably ranging from 40% by weight to 78% in weight.

4. A method according to any one of claims 1 to 3 wherein: - a single material M or two or three materials M are used; or - the mineral material M is synthetic or of natural origin, preferably selected from alkaline earth metal carbonate, preferably calcium carbonate (natural calcium carbonate or precipitated calcium carbonate), strontium carbonate, magnesium carbonate, barium carbonate, dolomite, kaolin, titanium dioxide, talc, lime, magnesium hydroxide, calcium sulfate, barium sulfate; or - the particles of ground mineral material M have a median size, measured by sedimentation, of less than 50 pm or a median size from 0.05 pm to 50 pm or a median size of less than 10 pm, preferably less than 5 pm or 2 pm, more preferably less than 1 pm or less than 0.5 pm.

5. A method according to any one of claims 1 to 4, wherein: - the polymer P has a molecular weight Mw, measured by CES, of 2,000 g / mol to 50,000 g / mol or of 1,500 g / mol to 40,000 g / mol, preferably of 2,000 g / mol to 25,000 g / mol or of 1,500 g / mol to 20,000 g / mol, more preferably of 2,000 g / mol to 20,000 g / mol, even more preferably of 2,000 g / mol to 15,000 g / mol, much more preferably of 3,000 g / mol to 13,000 g / mol or of 2,500 g / mol to 15,000 g / mol, particularly preferably of 3,500 g / mol to 20,000 g / mol or from 3,000 g / mol to 15,000 g / mol, most preferably from 3,500 g / mol to 15,000 g / mol and much more preferably from 3,500 g / mol to 13,000 g / mol; or - the polymer P has a polymolecularity index IP, measured by CES, of less than 5.5, preferably less than 4.5, more preferably less than 4;or - the polymer P has a polymolecularity index IP, measured by CES, ranging from 1.6 to 5.5, preferably ranging from 1.6 to 4.5, more preferably ranging from 1.6 to 4; or - the polymer P is totally or partially neutralized, preferably by means of an ion selected from a monovalent ion, a divalent ion and their combinations, more preferably by means of an ion selected from K+, Na+, Li+, NH4+, Mg2+, Ca2+ and their combinations; Also preferably, polymer P is totally or partially neutralized by means of at least one compound selected from LiOH, NaOH, KOH, Zn(OH)2, Mg(OH)2, Ca(OH)2, ZnO, MgO, CaO, ammonium derivatives, ammonia, ammonia, amino bases, for example triethanolamine, aminomethylpropanol, diethanolisopropylamine or 2-amino-2-methylpropanol (AMP) and their combinations, more preferably NaOH, Ca(OH)2, CaO and their combinations.;

6. A method according to any one of claims 1 to 5, wherein: - the polymerization reaction employs a combination of itaconic acid and an itaconate, preferably a combination of itaconic acid and an itaconate selected from sodium itaconate, potassium itaconate, lithium itaconate, ammonium itaconate; also preferably a combination of itaconic acid and an itaconate in a molar ratio of itaconic acid / itaconate combination ranging from 80 / 20 to 20 / 80, preferably ranging from 45 / 55 to 55 / 45; or - le polymère P est également préparé au moyen d'au moins un autre composé différent du composé Ml, de préférence de 0,5 % en poids à 30 % en poids d'un autre composé par rapport à la quantité totale en poids de monomères ; ou - Polymer P is also prepared using another compound selected from: * a compound M2 selected from acrylic acid, methacrylic acid, an acrylic acid oligomer, a methacrylic acid oligomer, an acrylic acid salt, a methacrylic acid salt, an acrylic acid oligomer salt, a methacrylic acid oligomer salt, maleic acid, maleic anhydride, crotonic acid, 2-acrylamido-2-methylpropane sulfonic acid, a salt of 2-acrylamido-2-methylpropane sulfonic acid, ethoxymethacrylate sulfonic acid, sodium methallyl sulfonate, styrene sulfonate, phosphated hydroxyethyl acrylate, phosphated hydroxyethyl methacrylate, phosphated hydroxypropyl acrylate, phosphated hydroxypropyl methacrylate, phosphated hydroxybutyl acrylate, phosphated hydroxybutyl methacrylate and their combinations; * a compound M3 independently selected from C1-C12 methacrylic acid esters, CrCi2 acrylic acid esters, acrylamide, N-tert-butylacrylamide, alkylacrylamides, N-methylolacrylamide, acrylonitrile, vinyl-lactam, N-vinylpyrrolidone, ureidomethacrylate, hydroxyethylacrylate, hydroxyethylmethacrylate, hydroxypropylacrylate, hydroxypropylmethacrylate, hydroxybutylmethacrylate, hydroxybutylacrylate, caprolactone methacrylate, caprolactone acrylate, polycaprolactone methacrylate, polycaprolactone acrylate, lactame methacrylate, lactame acrylate, polycaprolactame methacrylate, polycaprolactame acrylate, vinyl acetate and combinations thereof; preferably CrC8 methacrylic acid esters, CrC8 acrylic acid esters and combinations thereof; preferably, N-tert-butylacrylamide, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate,

7.

8. butylacrylate, more preferably methyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate and their combinations. Method according to any one of claims 1 to 6 wherein: - the polymerization reaction is carried out in the presence of an initiating compound selected from a peroxide (e.g. hydrogen peroxide, tert-butyl hydroperoxide), a persalt, preferably a persulfate (e.g. sodium persulfate, ammonium persulfate, potassium persulfate), their combinations and their associations with optionally a metal salt, preferably a metal salt selected from an iron salt (e.g. Fe11 or Fe111), a copper salt (e.g. Cu1 or Cu11) and their combinations;or - the polymerization reaction is carried out in the presence of at least one sulfur compound Tl comprising sulfur in oxidation state IV (sulfur IV or SIV), preferably the compound Tl is selected from lithium hydrogen sulfite, sodium hydrogen sulfite, potassium hydrogen sulfite, ammonium hydrogen sulfite, calcium di(hydrogen sulfite), magnesium di(hydrogen sulfite) and their combinations; also preferably, the compound Tl is used in an amount of 0.5% by weight to 15% by weight, preferably 1% by weight to 10% by weight, more preferably 1.5% by weight to 8% by weight, relative to the total dry weight amount of monomers used in the polymerization reaction; or; - The polymerization reaction is carried out in the presence of at least one phosphorus compound T2 comprising phosphorus in oxidation state I (phosphorus I or P1) or comprising phosphorus in oxidation state III (phosphorus III or P111). Preferably, compound T2 is selected from hypophosphorous acid, sodium hypophosphite, ammonium hypophosphite, phosphorous acid, sodium phosphite, and ammonium phosphite. Also preferably, compound T2 is used in an amount of 0.5% by weight to 15% by weight, preferably 1% by weight to 10% by weight, and more preferably 1.5% by weight to 8% by weight, relative to the total dry weight of monomers used in the polymerization reaction. A method according to any one of claims 1 to 7, wherein: - the compound Ml is present during the polymerization reaction in an amount by weight greater than 30%, preferably greater than 35% or 40%, more preferably greater than 45% or 50%, relative to all the compounds present in the reaction medium; or for which: - the polymerization reaction includes: * the preparation of a reaction medium comprising at least one compound Ml in an amount by weight greater than 35%, preferably greater than 50% or 60%, more preferably greater than 65% or 70%, relative to all the reactants in this reaction medium, then * the addition of the initiator compound, possibly separate addition of compound Tl or possibly of compound T2, and possibly separate addition of compound Ml and * the heating of the reaction medium.

9. A method according to any one of claims 1 to 8 wherein: - the polymer P is used in an amount from 0.05% to 5% by dry weight, preferably from 0.3% to 2.0% by dry weight, relative to the dry weight of particulate mineral matter M; or - the thermal concentration is carried out by heating, preferably at a heating temperature above 80°C or at a heating temperature below 95°C; or - the mechanical concentration is carried out by centrifugation or by means of a filter press or a rotary filter.

10. A method according to any one of claims 1 to 9 wherein: - the concentration of composition C in mineral matter M is greater than 60% by weight or greater than 65% by weight or greater than 70% by weight or is less than 78% by weight or is less than 75% by weight, preferably from 70% by weight to 78% by weight or from 70% by weight to 75% by weight of composition C; or wherein: - the Brookfield viscosity of composition C measured at 25°C, at 100 rpm 1 hour after preparation, is less than 800 mPa.s, preferably less than 600 mPa.s, more preferably less than 400 mPa.s; or whose Brookfield viscosity of composition C, measured at 25°C, at 100 rpm before stirring, measured 8 days after preparation, is less than 2,500 mPa·s, preferably less than 2,000 mPa·s, plus preferably less than 1,500 mPa.s or 1,000 mPa.s, much more preferably less than 800 mPa.s; or - the quantity of free polymer P not adsorbed on the mineral matter M, measured by determination of the quantity of total organic carbon by weight present in the water of composition C, is less than 45% by weight, preferably less than 35% by weight, relative to the total quantity of organic carbon of the polymer P introduced during the concentration; or - the cation demand of composition C measured using a "Mütek" apparatus is less in absolute value than -25 peq / g of composition C.

11. Aqueous composition C obtained according to the preparation method according to any one of claims 1 to 10.

12. Aqueous concentration agent D of a composition Cb according to any one of claims 1 to 10 comprising at least one polymer P defined according to any one of claims 1 to 8.

13. Method of preparing an aqueous composition Cm of mineral particles comprising: i. the preparation of an aqueous composition C according to any one of claims 1 to 11; ii. the preparation of an aqueous composition Cg comprising a mineral material Q in a concentration from 65 wt% to 78 wt% of composition Cg, and obtained by grinding in water of a mineral material Q in the presence of a grinding aid, preferably a (meth)acrylic polymer R; iii. the mixing under stirring of the aqueous composition C with the aqueous composition Cg.

14. A preparation method according to claim 13, wherein: - composition Cm comprises from 60% to 90% by dry weight of composition C and from 10% to 40% by dry weight of composition Cg, relative to the dry weight of composition Cm; or - the concentration of minerals M and Q in composition Cm is greater than 45% by weight, or 50% by weight, or 70% by weight, or less than 78% by weight, or less than 75% by weight, preferably ranging from 70% by weight to 78% by weight or from 70% by weight to 75% by weight of composition Cm; or wherein: - the Brookfield viscosity of the composition Cm measured at 25°C, at 100 rpm 1 hour after preparation, is less than 800 mPa.s, preferably less than 600 mPa.s; or whose - the Brookfield viscosity of the composition Cm measured at 25°C, at 100 rpm before stirring, measured 8 days after preparation is less than 2,500 mPa.s, preferably less than 2,000 mPa.s, more preferably less than 2,000 mPa.s or 1,000 mPa.s.

15. Aqueous composition Cm obtained according to the preparation method according to one of claims 13 or 14.

16. Method for controlling the viscosity of a composition Cm according to claim 15 comprising the implementation of at least one polymer P according to any one of claims 1 to 8 or of an aqueous concentration or dispersion agent according to claim 12.

17. Aqueous paper preparation composition selected from a paper mass filler composition and a paper coating sauce composition comprising: - a composition C according to claim 11 or a composition Cm according to claim 15 and optionally - at least one binding compound, and optionally at least one compound selected from a rheology modifier compound, a water retainer and an optical brightener.

18. Paper preparation method comprising the application of a composition C according to claim 11 or a composition Cm according to claim 15.