Coating color composition

Abstract

The invention relates to a paper coating color composition comprising in particular an aqueous rheological agent combining a polyalkoxylated hydrophobic compound and a water-soluble copolymer prepared in the presence of a dialkyl sulfosuccinate derivative. The invention also relates to the use of said composition for the preparation of paper or cardboard as well as to said aqueous rheological agent which makes it possible to effectively control the different viscosity components of the coating color, while improving the water retention of the composition.

Description

[0001] COATING SAUCE COMPOSITION

[0002] The invention relates to a paper coating composition comprising in particular an aqueous rheological agent combining a polyalkoxylated hydrophobic compound and a water-soluble copolymer prepared in the presence of a dialkylsulfosuccinate derivative. The invention also relates to the use of this composition for the preparation of paper or cardboard as well as this aqueous rheological agent which makes it possible to effectively control the different viscosity components of the coating slip, while improving its water retention.

[0003] In addition to improving the final properties of paper prepared using these coating colors, it is also necessary to improve the preparation conditions and the processing conditions of these paper coating color compositions.

[0004] In addition, these compositions must have viscosities under different shear gradients that allow them to be used effectively, particularly when applied to the surface of a sheet of paper. These compositions must have an apparent viscosity, therefore under low shear gradient, which is well suited to effective application.

[0005] Furthermore, increasing viscosities under high and low shear rates can have consequences on the phenomenon of migration of water and water-soluble substances through the paper. This migration must be reduced as much as possible, in particular to avoid changes in the rheology of the unused coating color recycled in the coating process. It is therefore necessary to carefully control the water retention of the coating color.

[0006] In addition, the viscosity of the compositions must be controlled and allow them to be pumped or filtered easily, particularly in the supply circuits of paper coating processes.

[0007] Paper coating sauce preparation compositions include insoluble materials, including mineral particles. A high concentration and high solids content of these compositions are often sought, although increasing the concentration or solids content increases the risk of viscosity drift, especially at high shear rates.

[0008] The possibility of effectively implementing very small mineral particles is also being sought, particularly to improve the optical properties of paper. However, these very small mineral particles can disrupt the viscosity and stability of paper coating compositions.

[0009] These compositions must also limit or prevent sedimentation of the particles used. They must also limit, or even prevent, the formation of foam or splashes.

[0010] The compatibility of the different components of a paper coating sauce must also be taken into account. In particular, it is important to have good compatibility with the latex binder used.

[0011] Thickening copolymers used for the preparation of paper coatings as well as rheological additives are known.

[0012] However, known rheological agents do not always provide a satisfactory solution to these various problems. EP 2776518 describes a paper coating color comprising a HASE polymer prepared in the presence of a sodium salt of fatty alcohol sulfate and / -docecyl mercaptan or / / -docecyl mercaptan. EP 3122791 describes a binder latex prepared in the presence of dialkylsulfosuccinate with vinyl acetate, a monomer with a silane group and with small amounts of acrylic acid and (meth)acrylate ester. EP 2788549 describes the preparation of copolymers in the presence of sodium salts of dialkylesters of sulfosuccinic acid.

[0013] There is therefore a need for improved rheological agents to provide paper coating compositions.

[0014] The aqueous paper coating composition according to the invention makes it possible to provide a solution to all or part of the problems of the compositions of the prior art. Thus, the invention provides an aqueous paper coating composition C comprising: at least one aqueous rheological agent R comprising:

[0015] • at least one water-soluble copolymer P prepared by polymerization reaction in the presence of at least one compound E chosen from dialkylsulfosuccinate, sodium salt of dialkylsulfosuccinate and combinations thereof: o of at least one compound (a) chosen from methacrylic acid, a salt of methacrylic acid, an oligomer of methacrylic acid, a salt of oligomer of methacrylic acid, acrylic acid, a salt of acrylic acid, an oligomer of acrylic acid, a salt of oligomer of acrylic acid, their salts and combinations thereof; o of at least one compound (b) chosen from Ci-Cio-alkyl methacrylate, Ci-Cio-alkyl acrylate, styrene, vinylcaprolactam, vinylacetate and combinations thereof;

[0016] • at least one compound F of formula I:

[0017] R-(OE) X-OH) in which R represents a linear C6-C4o-alkyl group or a branched C6-C4o-alkyl group, OE represents an ethylene oxy group and x represents a number ranging from 1 to 50; particles of at least one mineral material M; at least one binding agent L and water.

[0018] Preferably according to the invention, the composition C according to the invention comprises a polymer P prepared in the presence of a compound E chosen from dioctylsulfosuccinate, sodium salt of dioctylsulfosuccinate and their combinations, optionally associated with at least one mercaptan compound. Preferably according to the invention, the mercaptan compound comprises a linear Cs-Ci6-alkyl group or a branched Cs-Ci6-alkyl group, more preferably, the mercaptan compound is chosen from / c / V-nonylmercaptan, tert-dodecylmercaptan, w-dodecylmercaptan and their combinations. More preferably, the compound E is / c / V-nonylmercaptan.

[0019] According to the invention, the polymer P is water-soluble, preferably at a pH greater than 5, more preferably at a pH greater than 6.

[0020] Preferably according to the invention, the polymer P has a molecular mass Mw, measured by CES, ranging from 20,000 g / mol to 800,000 g / mol or from 20,000 g / mol to 500,000 g / mol, more preferably from 20,000 g / mol to 400,000 g / mol or from 20,000 g / mol to 300,000 g / mol.

[0021] According to the invention, the molecular mass Mw is determined by Size Exclusion Chromatography (SEC) or in English "Gel Permeation Chromatography" (GPC). This technique uses a "Waters" brand liquid chromatography apparatus equipped with a detector. This detector is a "Waters" brand refractometric concentration detector. This liquid chromatography apparatus is equipped with a size exclusion column in order to separate the different molecular weights of the copolymers studied. The liquid elution phase is an aqueous phase adjusted to pH 9.00 using 1 N sodium hydroxide containing 0.05 M NaHCCh, 0.1 M NaNCh, 0.02 M triethanolamine and 0.03% NaNs. In a first step, the copolymer solution is diluted to 0.9% dry in the CES solubilization solvent, which corresponds to the liquid elution phase of the CES to which 0.04% dimethylformamide is added, which acts as a flow marker or internal standard.Then, it is filtered at 0.2 µm. 100 µL are then injected into the chromatography apparatus (eluent: an aqueous phase adjusted to pH 9.00 with 1N sodium hydroxide containing 0.05 M NaHCCh, 0.1 M NaNCh, 0.02 M triethanolamine and 0.03% NaN3).

[0022] The liquid chromatography apparatus contains an isocratic pump ("Waters" 515) whose flow rate is set at 0.8 mL / min. The chromatography apparatus also includes an oven which itself includes in series the following column system: a precolumn of the "Guard Column Ultrahydrogel Waters" type, 6 cm long and 40 mm inner diameter and a linear column of the "Ultrahydrogel Waters" type, 30 cm long and 7.8 mm inner diameter. The detection system consists of a refractometric detector of the "RI Waters" 410 type. The oven is heated to a temperature of 60°C and the refractometer is heated to a temperature of 45°C. The chromatography apparatus is calibrated using powdered sodium polyacrylate standards of different molecular masses certified by the supplier: Polymer Standards Service or American Polymers Standards Corporation (molecular mass ranging from 900 to 2,250,000 g / mol and polydispersity index ranging from 1.4 to 1.7).

[0023] Preferably according to the invention, the polymer P is totally or partially acidic or totally or partially neutralized. More preferably, the polymer P is partially neutralized, preferably by means of at least one compound chosen from LiOH, NaOH, KOH, Zn(OH)2, Mg(OH)2, Ca(OH)2, ZnO, MgO, CaO, ammonium derivatives, ammonia, aqueous ammonia, amine bases, for example triethanolamine, aminomethylpropanol or 2-amino-2-methyl-propanol (AMP) and combinations thereof. More preferably, the polymer P is neutralized by means of LiOH, NaOH, KOH, Mg(OH)2, Ca(OH)2, aqueous ammonia and combinations thereof.

[0024] Essentially according to the invention, the polymer P is prepared by polymerization reaction of at least one monomer (a) and at least one monomer (b), in the presence of at least one compound E.

[0025] Preferably according to the invention, the monomer (a) is methacrylic acid alone or combined with acrylic acid. More preferably when using acrylic acid, the quantity by mass of acrylic acid is less than the quantity by mass of methacrylic acid. Also preferably according to the invention, the monomer (b) is chosen from C1-C4-alkyl acrylate, C1-C4-alkyl methacrylate and combinations thereof. More preferably, the monomer (b) is chosen from methyl acrylate, ethyl acrylate, propyl acrylate, isobutyl acrylate, / / -butyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isobutyl methacrylate, / / -butyl methacrylate, aryl acrylate, in particular phenyl acrylate, benzyl acrylate, phenoxyethylacrylate, aryl methacrylate, in particular preferably phenylmethacrylate, benzylmethacrylate, phenoxyethylmethacrylate and combinations thereof.Much more preferably, it is chosen from methyl acrylate, ethyl acrylate, isobutyl acrylate, / / -butyl acrylate, methyl methacrylate, even more preferably chosen from methyl acrylate and ethyl acrylate.

[0026] In addition to monomers (a) and (b), polymer P can also be prepared using one or more other monomers. Then, preferably according to the invention, copolymer P can be prepared by a polymerization reaction also using at least one compound (c) of formula II:

[0027] RE(OE)æ'(OP)nR 2 in which: m or n is different from 0; m independently represents 0 or a number less than 150; n independently represents 0 or a number less than 150;

[0028] OE represents an oxyethylene group;

[0029] OP independently represents an oxypropylene group;

[0030] - R 1represents a group comprising at least one polymerizable olefinic unsaturation, preferably a group chosen from acrylate, methacrylate, acrylurethane, methacrylurethane, vinyl, allyl, methallyl and isoprenyl; more preferably a methacrylate group;

[0031] - R 2 represents a linear, branched or cyclic, saturated, unsaturated or aromatic hydrocarbon group comprising from 6 to 40 carbon atoms, preferably a linear or branched C6-C4o-alkyl group, preferably a linear or branched Cs-Cso-alkyl group, a C6-C4o-aryl group, preferably a Cs-Cso-aryl group, for example a tristyrylphenyl group.

[0032] Preferably according to the invention, compound (c) is a compound of formula II in which: m represents an integer or decimal number ranging from 20 to 40 and n is zero or m and n independently represent an integer or decimal number ranging from 5 to 100 or the mass ratio m / n ranges from 90 / 10 to 70 / 30.

[0033] More preferably according to the invention, compound (c) is a compound of formula II in which: m independently represents a number ranging from 2 to 50; n independently represents 0;

[0034] OE represents an oxyethylene group;

[0035] - R 1 represents a group comprising at least one polymerizable olefinic unsaturation, preferably a group chosen from acrylate, methacrylate, vinyl, allyl, methallyl and isoprenyl; more preferably a methacrylate group;

[0036] - R 2represents a linear, branched or cyclic, saturated, unsaturated or aromatic hydrocarbon group comprising from 6 to 40 carbon atoms, preferably a linear or branched C6-C4o-alkyl group, preferably a linear or branched Cs-Cso-alkyl group, a C6-C -aryl group, preferably a Cs-Cso-aryl group, for example a tristyrylphenyl group.

[0037] According to the invention, the polymerization reaction may also use at least one compound (d) chosen from: polyalkylene glycol acrylate, preferably from polyethylene glycol acrylate and polyethylenepolypropylene glycol acrylate, polyalkylene glycol methacrylate, preferably from polyethylene glycol methacrylate and polyethylenepolypropylene glycol methacrylate, allylpolyalkylene glycol, preferably from allylpolyethylene glycol and allylpolyethylenepolypropylene glycol, methallylpolyalkylene glycol, preferably from methallylpolyethylene glycol and methallylpolyethylenepolypropylene glycol, 3-methyl-3-buten-1-ylpolyalkylene glycol, preferably from 3-methyl-3-buten-1-ylpolyethylene glycol and 3-methyl-3-buten-1-ylpolyethylenepolypropylene glycol.

[0038] According to the invention, the polymerization reaction may also use at least one crosslinking compound (e) or at least one compound (e) comprising at least two olefinic unsaturations. However, preferably according to the invention, the polymerization reaction does not use compound (e).

[0039] According to the invention, the polymerization reaction may also use at least one compound chosen from 2-acrylamido-2-methylpropane sulfonic acid, 2-sulfoethyl methacrylate, sodium methallyl sulfonate, styrene sulfonate, their salts and their combinations. However, preferably according to the invention, the polymerization reaction does not use a compound chosen from 2-acrylamido-2-methylpropane sulfonic acid, 2-sulfoethyl methacrylate, sodium methallyl sulfonate, styrene sulfonate and their salts.

[0040] The proportions of the different monomers used during the preparation of the copolymer P can vary within fairly wide proportions. Preferably, the copolymer P comprises, relative to the total quantity by mass of monomers: from 20% to 50% by mass of monomer (a) and from 50% to 80% by mass of monomer (b); or from 35% to 44.9% by mass of monomer (a), from 55% to 74.9% by mass of monomer (b) and from 0.1% to 10% by mass of monomer (c); or from 40% to 44.9% by mass of monomer (a), from 55% to 74.9% by mass of monomer (b) and from 0.1% to 5% by mass of monomer (d); or from 40% to 44.9% by mass of monomer (a), from 55% to 74.9% by mass of monomer (b) and from 0.1% to 5% by mass of monomer (e); or from 30% to 44.8% by mass of monomer (a), from 55% to 74.8% by mass of monomer (b), from 0.1% to 10% by mass of monomer (c) and from 0.1% to 5% by mass of monomer (d);or from 30% to 44.8% by mass of monomer (a), from 55% to 74.8% by mass of monomer (b), from 0.1% to 10% by mass of monomer (c) and from 0.1% to 5% by mass of monomer (e); or from 35% to 44.8% by mass of monomer (a), from 55% to 74.8% by mass of monomer (b), from 0.1% to 5% by mass of monomer (d) and from 0.1% to 5% by mass of monomer (e); or from 25% to 44.7% by mass of monomer (a), from 55% to 74.7% by mass of monomer (b), from 0.1% to 10% by mass of monomer (c), from 0.1% to 5% by mass of monomer (d) and from 0.1% to 5% by mass of monomer (e).;

[0041] Essentially according to the invention, the rheological agent R comprises at least one compound F of formula I. Preferably according to the invention, the compound F is a compound of formula I in which R represents a linear C6-C4o-alkyl group, preferably a linear C12-C24-alkyl group.

[0042] Also preferably according to the invention, compound F is a compound of formula I in which x represents a number ranging from 1 to 30, preferably a number ranging from 5 to 25. More preferably according to the invention, R represents a linear C6-C4o-alkyl group, preferably a linear C12-C24-alkyl group, and x represents a number ranging from 1 to 30.

[0043] More preferably according to the invention, compound F is a compound of formula I in which x represents a number ranging from 1 to 30, preferably a number ranging from 5 to 25. More preferably according to the invention, R represents a linear C6-C4o-alkyl group, preferably a linear C12-C24-alkyl group, and x represents a number ranging from 5 to 25.

[0044] In addition to water, the rheological agent R according to the invention also comprises the water-soluble copolymer P and the compound F of formula I. The amounts of these components may vary. Preferably, for the composition C according to the invention, the aqueous rheological agent R comprises from 0.05% to 5%, preferably from 0.1% to 2%, by dry mass of compound F, relative to the dry mass quantity of copolymer P.

[0045] In addition to water, the aqueous composition C according to the invention also comprises an aqueous rheological agent R, particles of at least one mineral material M and a binding agent L. The amounts of these components may vary. Preferably according to the invention, the composition according to the invention comprises, relative to the mass quantity of the composition: from 0.02% to 2% dry by mass of aqueous rheological agent R; from 30% to 90% dry by mass of particles of mineral material M; from 2% to 25% dry by mass of binding agent L and from 7.98% to 44.98% by mass of water.

[0046] Essentially, the composition C according to the invention comprises a mineral material M in particulate form. Preferably according to the invention, the particles of mineral material M have a size of less than 50 pm or a size ranging from 0.05 pm to 50 pm or a 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.

[0047] Also preferably according to the invention, the particles of mineral material M have a spherical equivalent diameter, for a size ranging from 0.05 pm to 50 pm or less than 50 pm, preferably for a size less than 10 pm, more preferably less than 5 qm or 2 pm, even more preferably less than 1 pm or less than 0.5 pm, which is equal to 60% by weight or equal to 70% by weight.

[0048] More preferably according to the invention, the particles of mineral material M have a spherical equivalent diameter, for a size ranging from 0.05 pm to 50 pm or less than 50 pm, preferably for a size less than 10 pm, more preferably less than 5 pm or 2 pm, even more preferably less than 1 pm or less than 0.5 pm, which is equal to 80% by weight or even equal to 90% by weight.

[0049] According to the invention, composition C may comprise a single mineral material M or comprise two or three mineral materials M. Preferably, composition C comprises a single mineral material M.

[0050] Preferably according to the invention, the mineral material M is synthetic or of natural origin. More preferably, it is chosen 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, calcium sulfate, barium sulfate, silicas. More preferably, the material M is calcium carbonate (natural calcium carbonate or precipitated calcium carbonate) or kaolin.

[0051] Preferably according to the invention, the binding agent L is a natural binding agent such as starch, carboxymethylcellulose (CMC), hydroxyethylcelluloses, polyvinyl alcohol (PVOH), casein, proteins, alginates, or a synthetic binding agent such as a latex. More preferably, the binding agent L is chosen from a styrene-butadiene polymer, a styrene-acrylic polymer, a styrene-acetate polymer, and even more preferably a styrene-butadiene polymer.

[0052] In addition to the aqueous rheological agent R, the particles of mineral material M and the binding agent L, the composition C according to the invention may also comprise at least one adjuvant, in particular at least one adjuvant chosen from dispersing agents, anti-foaming agents, biocidal agents, coloring agents, lubricating agents and optical brightening agents.

[0053] Composition C according to the invention has several advantageous properties. These properties are particularly effective in the preparation of paper or cardboard. Thus, the invention also provides a method for preparing paper or cardboard comprising the use of an aqueous composition C according to the invention. Preferably, this composition C is used during one or more stages of coating the paper or cardboard. The paper coating colors prepared according to the invention are particularly advantageous in the preparation of a primary coating layer (pre-coat) or in the preparation of a final coating layer of paper (top-coat) or even a simple layer.

[0054] In addition, when implementing the method for preparing paper or cardboard comprising the use of an aqueous composition according to the invention, the water retention of the composition during the coating of the paper is improved. Preferably according to the invention, the water retention of composition C, measured according to the method of the examples, during the coating of the paper is improved by 50% to 400% by volume compared to the absence of use of copolymer P.

[0055] Also, when implementing the method for preparing paper or cardboard comprising the use of an aqueous composition C according to the invention, the viscosity of the composition is controlled thanks to the properties of the copolymer P. Preferably, the method according to the invention comprises the use of a composition C according to the invention which has a Brookfield viscosity, measured at 100 rpm and at 25°C according to the method of the examples, which is sufficient and compatible for the coating process and this viscosity is higher than that of the composition free of copolymer P.

[0056] More preferably according to the invention, the Brookfield viscosity of composition C, measured at 100 rpm and at 25°C according to the method of the examples, ranges from 150 mPa.s to 3,500 mPa.s, more preferably from 500 mPa.s to 2,000 mPa.s.

[0057] Also more preferably according to the invention, the capillary viscosity of composition C, measured at 1,000,000 s' 1 and at 25°C according to the method of the examples, ranges from 10 mPa.s to 100 mPa.s, more preferably from 20 mPa.s to 80 mPa.s.

[0058] Also preferably when using composition C according to the invention for the preparation of paper or cardboard, the composition is deposited on the surface of the paper or cardboard during at least one coating step with a deposit, after drying, of 5 to 50 g / m 2 , more preferably from 8 to 40 g / m 2 , measured according to the example method.

[0059] Coating can be achieved by a blade or pencil coating process, a film transfer press, an air knife, a size press or curtain coating.

[0060] Essentially according to the invention, the aqueous paper coating composition C comprises the aqueous rheological agent R giving it numerous properties sought after for the preparation of paper or cardboard, in particular the control of its viscosity and in particular its viscosity at high shear gradient. Thus, the invention provides a method for controlling the viscosity at high gradient, measured at 1,000,000 s' 1 and at 25°C according to the method of the examples, of an aqueous paper coating composition C comprising particles of at least one mineral material M, at least one binding agent L and water, comprising the addition to the composition of at least one aqueous rheological agent R comprising: at least one water-soluble copolymer P prepared by polymerization reaction in the presence of at least one compound E chosen from dialkylsulfosuccinate, sodium salt of dialkylsulfosuccinate and their combinations:

[0061] • at least one compound (a) chosen from methacrylic acid, a methacrylic acid salt, a methacrylic acid oligomer, a methacrylic acid oligomer salt, acrylic acid, an acrylic acid salt, an acrylic acid oligomer, a acrylic acid oligomer salt and combinations thereof;

[0062] • at least one compound (b) chosen from Ci-Cio-alkyl methacrylate, Ci-Cio-alkyl acrylate, styrene, vinylcaprolactam, vinylacetate and combinations thereof; at least one compound F of formula I:

[0063] R-(OE) X -OH) in which R represents a linear C6-C4o-alkyl group or a branched C6-C4o-alkyl group, OE represents an ethylene oxy group and x represents a number ranging from 1 to 50.

[0064] Essentially according to the invention, the agent R combines the copolymer P and the compound F. According to the invention, the agent R can be prepared prior to its introduction into an aqueous composition, preferably into an aqueous paper coating composition. According to the invention, the agent R can also be prepared extemporaneously during the introduction of the copolymer P and the compound F into an aqueous composition, preferably into an aqueous paper coating composition.

[0065] The invention therefore also provides an aqueous rheological agent R combining: at least one water-soluble copolymer P prepared by polymerization reaction in the presence of at least one compound E chosen from dialkylsulfosuccinate, sodium salt of dialkylsulfosuccinate and their combinations:

[0066] • at least one compound (a) chosen from methacrylic acid, a methacrylic acid salt, a methacrylic acid oligomer, a methacrylic acid oligomer salt, acrylic acid, an acrylic acid salt, an acrylic acid oligomer, a acrylic acid oligomer salt and combinations thereof;

[0067] • at least one compound (b) chosen from Ci-Cio-alkyl methacrylate, Ci-Cio-alkyl acrylate, styrene, vinylcaprolactam, vinylacetate and combinations thereof; at least one compound F of formula I:

[0068] R-(OE) X -OH) in which R represents a linear C6-C4o-alkyl group or a branched C6-C4o-alkyl group, OE represents an ethylene oxy group and x represents a number ranging from 1 to 50.

[0069] According to the invention, the agent R can be prepared beforehand. Thus, the invention also provides an aqueous rheological agent R comprising: at least one water-soluble copolymer P prepared by polymerization reaction in the presence of at least one compound E chosen from dialkylsulfosuccinate, sodium salt of dialkylsulfosuccinate and their combinations:

[0070] • at least one compound (a) chosen from methacrylic acid, a methacrylic acid salt, a methacrylic acid oligomer, a methacrylic acid oligomer salt, acrylic acid, an acrylic acid salt, an acrylic acid oligomer, a acrylic acid oligomer salt and combinations thereof;

[0071] • at least one compound (b) chosen from Ci-Cio-alkyl methacrylate, Ci-Cio-alkyl acrylate, styrene, vinylcaprolactam, vinylacetate and combinations thereof; at least one compound F of formula I:

[0072] R-(OE) X-OH (J) in which R represents a linear C6-C4o-alkyl group or a branched C6-C4o-alkyl group, OE represents an ethylene oxy group and x represents a number ranging from 1 to 50.

[0073] Preferably according to the invention, the aqueous rheological agent R comprises a polymer P and a compound F defined according to the invention. The particular, advantageous or preferred characteristics of the composition C according to the invention define methods as well as agents R according to the invention which are also particular, advantageous or preferred.

[0074] The following examples illustrate the various aspects of the invention, in particular the preparation and characterization of paper coating compositions according to the invention.

[0075] EXAMPLES

[0076] Preparation of polymers PI and P2 according to the invention and of rheological agents RI and R2 according to the invention:

[0077] The following compounds are used: compound (a), AMA: methacrylic acid, compound (b), AE: ethyl acrylate, compound E, DOS: dioctylsulfosuccinate 50% solution in water,

[0078] / c / V-nonyl mercaptan, sodium persulfate, (NH4)2S20s, sodium metabisulfite, Na2S2O5, compound Fl, Genapol T200 Clariant: w-Ciô-Cis-alkyl alcohol ethoxylated 20 times, compound F2, Genapol UD088 Clariant: oxo-Cn-alkyl alcohol ethoxylated 8 times.

[0079] In a 1 L reactor stirred and heated using an oil bath, mixture 1 is prepared by introducing deionized water and a solution of dioctylsulfosuccinate. A mixture 2 of monomers is prepared, with stirring in a beaker, comprising in deionized water: monomer (a), AMA, monomer (b), AE,

[0080] - a 50% aqueous solution of dioctylsulfosuccinate, transfer agent, / c / V-nonyl mercaptan.

[0081] An initiator solution is prepared comprising ammonium persulfate, deionized water and sodium metabisulfite. The reactor is heated to 76 ± 1°C and then the initiator solution is injected as well as mixture 2 for 2 hours. Then, heating is carried out for 1 hour at 80 ± 1°C. The whole is then cooled to room temperature. Finally, compound F is added. The reagents and quantities used as well as the characteristics of polymers PI and P2 and agents RI and R2 are presented in Table 1.

[0082] Table 1

[0083] Preparation and characterization of compositions C1, C2 and C3 according to the invention:

[0084] The pH is measured at 25°C with a pH meter (WTW) equipped with a conventional electrode coupled to a temperature probe. The dry extract is measured dry using a microwave balance (CEM). A determined mass between 1 and 4 g of composition is placed on sandpaper. Then, the balance dries this mass by microwave. The balance stops drying when the weight no longer varies for 10 seconds. The weight difference is expressed in %; this determines the dry extract. Using an analog viscometer, the Brookfield viscosity of the compositions prepared at 100 rpm and 25°C is measured. The spindle is chosen according to the viscosity of the composition in question in order to be within the optimal operating range of the rheometer.

[0085] Capillary viscosity at 25°C and at 10 6 if 1is measured using a capillary viscometer (AC AV A2 ACA). Water retention is determined at 25°C using a retentiometer (AAGWR Gradek) which includes a measuring chamber in which a test paper (Test Blotter Paper Gradek) is placed, covered by a perforated plastic cloth (Test Filter PCTE Gradek - 2 pm). 10 mL of composition is then introduced into the chamber. The AAGWR device allows pressure (1.5 bar) to be exerted on the composition, causing all or part of the water and water-soluble substances contained in the composition to pass through the perforated plastic cloth and migrate into the test paper. A pressure of 1.5 bar is applied for 90 seconds. The difference between the weight of the test paper before the measurement (PO) and after the measurement (PI) gives the quantity of water and water-soluble substances contained in the composition which have migrated into the test paper during the measurement.The relative value of increased water retention is equal to 1250 x (PI - PO) / PO.

[0086] 90 parts by mass of particles of material M (calcium carbonate, "Hydrocarb 95" "Omya"), 10 parts by mass of particles of a second material M (kaolin, "Capim DG" "Imerys"), 0.15 parts of a dispersing agent (sodium polyacrylate "Topseperse GX N" "COATEX"), 10 parts of a binding agent L (styrene-butadiene latex DL 1066 "Trinseo"), 0.5 parts of an optical brightener ("Blankophor 4900") are mixed with stirring.

[0087] This mixture has a dry extract of 67% and a pH of 9 as well as a capillary viscosity of 60 mPa.s measured at 1,000,000 s' 1 .

[0088] Composition Cl according to the invention is obtained by adding C, with stirring using a “VMI Turbotest” motor, 0.2 parts by mass of agent RI to this mixture. The characteristics of composition Cl according to the invention are measured: Brookfield viscosity at 100 rpm: 1000 mPa.s, water retention: 210 g / m 2 ,

[0089] - capillary viscosity: 65 mPa.s.

[0090] In a similar manner, composition C2 according to the invention is prepared and characterized using 0.2 parts by mass of agent R2: Brookfield viscosity at 100 rpm: 1000 mPa.s, water retention: 185 g / m 2 ,

[0091] - capillary viscosity: 65 mPa.s.

[0092] In a similar manner, composition C3 according to the invention is prepared and characterized using 0.2 parts by mass of agent R3: Brookfield viscosity at 100 rpm: 950 mPa.s, water retention: 210 g / m 2 ,

[0093] - capillary viscosity: 70 mPa.s.

[0094] The agents RI, R2 and R3 combining the compounds F1 or F2 and, respectively, the polymers P1, P2 and P3 according to the invention make it possible to prepare aqueous paper coating compositions C having a Brookfield viscosity allowing easy use during the preparation of the paper.

[0095] Agents RI, R2 and R3 are particularly effective in limiting capillary viscosity and in improving water retention of aqueous paper coating compositions C.

Claims

CLAIMS 1. Aqueous paper coating composition C comprising: at least one aqueous rheological agent R comprising: • at least one water-soluble copolymer P prepared by polymerization reaction in the presence of at least one compound E chosen from dialkylsulfosuccinate, sodium salt of dialkylsulfosuccinate and combinations thereof: o of at least one compound (a) chosen from methacrylic acid, a salt of methacrylic acid, an oligomer of methacrylic acid, a salt of oligomer of methacrylic acid, acrylic acid, a salt of acrylic acid, an oligomer of acrylic acid, a salt of oligomer of acrylic acid, their salts and combinations thereof; o of at least one compound (b) chosen from Ci-Cio-alkyl methacrylate, Ci-Cio-alkyl acrylate, styrene, vinylcaprolactam, vinylacetate and combinations thereof; • at least one compound F of formula I: R-(OE OH ) in which R represents a linear C6-C4o-alkyl group or a branched C6-C4o-alkyl group, OE represents an ethylene oxy group and x represents a number ranging from 1 to 50; particles of at least one mineral material M; at least one binding agent L and water.

2. Composition according to claim 1 for which: the polymer P is prepared in the presence of a compound E chosen from dioctylsulfosuccinate, sodium salt of dioctylsulfosuccinate and their combinations, optionally associated with at least one mercaptan compound, preferably a mercaptan compound comprising a linear Cs-Ci6-alkyl group or a branched Cs-Ci6-alkyl group, more preferably a mercaptan compound chosen from / c / V-nonyl mercaptan, / c / V-docecyl mercaptan, / / -dodecyl mercaptan and their combinations; or the polymer P is water-soluble at a pH greater than 5, preferably at a pH greater than 6; or the polymer P has a molecular mass Mw, measured by CES, ranging from 20,000 g / mol to 800,000 g / mol or from 20,000 g / mol to 500,000 g / mol, preferably from 20,000 g / mol to 400,000 g / mol or from 20,000 g / mol to 300,000 g / mol; or the polymer P is totally or partially acidic or totally or partially neutralized, preferably the polymer P is partially neutralized, preferably by means of at least one compound chosen from LiOH, NaOH, KOH, Zn(OH)2, Mg(OH)2, Ca(OH)2, ZnO, MgO, CaO, ammonium derivatives, ammonia, aqueous ammonia, amine bases, for example triethanolamine, aminomethylpropanol or 2-amino-2-methyl-propanol (AMP) and combinations thereof, more preferably LiOH, NaOH, KOH, Mg(OH)2, Ca(OH)2, aqueous ammonia and combinations thereof.

3. Composition according to one of claims 1 or 2 for which: the monomer (a) is methacrylic acid alone or combined with acrylic acid, preferably in an amount by mass of acrylic acid less than the amount by mass of methacrylic acid; or the monomer (b) is chosen from C1-C4-alkyl acrylate, C1-C4-alkyl methacrylate and combinations thereof; preferably chosen from methyl acrylate, ethyl acrylate, propyl acrylate, isobutyl acrylate, w-butyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isobutyl methacrylate, w-butyl methacrylate, aryl acrylate, in particular phenylacrylate, benzylacrylate, phenoxyethylacrylate, aryl methacrylate, in particular preferably phenylmethacrylate, benzylmethacrylate, phenoxyethylmethacrylate and combinations thereof;more preferably chosen from methyl acrylate, ethyl acrylate, isobutyl acrylate, w-butyl acrylate, methyl methacrylate, even more preferably chosen from methyl acrylate and ethyl acrylate.; 4. Composition according to one of claims 1 to 3 for which the copolymer P is prepared by a polymerization reaction also using: at least one compound (c) of formula II: R 5 '(OE)œ-(OP R 2 (II) in which: m or n is different from 0; m independently represents 0 or a number less than 150; n independently represents 0 or a number less than 150; OE represents an oxyethylene group; OP independently represents an oxypropylene group; - R 1represents a group comprising at least one polymerizable olefinic unsaturation, preferably a group chosen from acrylate, methacrylate, acrylurethane, methacrylurethane, vinyl, allyl, methallyl and isoprenyl; more preferably a methacrylate group; - R 2 represents a linear, branched or cyclic, saturated, unsaturated or aromatic hydrocarbon group comprising from 6 to 40 carbon atoms, preferably a linear or branched C6-C4o-alkyl group, preferably a linear or branched Cs-Cso-alkyl group, a C6-C4o-aryl group, preferably a Cs-Cso-aryl group, for example a tristyrylphenyl group; preferably compound (c) is a compound of formula II in which: m represents an integer or decimal number ranging from 20 to 40 and n is zero or m and n independently represent an integer or decimal number ranging from 5 to 100 or the mass ratio m / n ranges from 90 / 10 to 70 / 30; or • at least one compound (d) chosen from: polyalkylene glycol acrylate, preferably from polyethylene glycol acrylate and polyethylenepolypropylene glycol acrylate, polyalkylene glycol methacrylate, preferably from polyethylene glycol methacrylate and polyethylenepolypropylene glycol methacrylate, allylpolyalkylene glycol, preferably from allylpolyethylene glycol and allylpolyethylenepolypropylene glycol, methallylpolyalkylene glycol, preferably from methallylpolyethylene glycol and methallylpolyethylenepolypropylene glycol, 3-methyl-3-buten-1-ylpolyalkylene glycol, preferably from 3-methyl-3-buten-1-ylpolyethylene glycol and 3-methyl-3-buten-1-ylpolyethylenepolypropylene glycol; or at least one crosslinking compound (e) or at least one compound (e) comprising at least two olefinic unsaturations.

5. Composition according to one of claims 1 to 4 for which the copolymer P comprises, relative to the total quantity by mass of monomers: from 20% to 50% by mass of monomer (a) and from 50% to 80% by mass of monomer (b); or from 35% to 44.9% by mass of monomer (a), from 55% to 74.9% by mass of monomer (b) and from 0.1% to 10% by mass of monomer (c); or from 40% to 44.9% by mass of monomer (a), from 55% to 74.9% by mass of monomer (b) and from 0.1% to 5% by mass of monomer (d); or from 40% to 44.9% by mass of monomer (a), from 55% to 74.9% by mass of monomer (b) and from 0.1% to 5% by mass of monomer (e); or from 30% to 44.8% by mass of monomer (a), from 55% to 74.8% by mass of monomer (b), from 0.1% to 10% by mass of monomer (c) and from 0.1% to 5% by mass of monomer (d); or from 30% to 44.8% by mass of monomer (a), from 55% to 74.8% by mass of monomer (b), from 0.1% to 10% by mass of monomer (c) and from 0.1% to 5% by mass of monomer (e);or from 35% to 44.8% by mass of monomer (a), from 55% to 74.8% by mass of monomer (b), from 0.1% to 5% by mass of monomer (d) and from 0.1% to 5% by mass of monomer (e); or from 25% to 44.7% by mass of monomer (a), from 55% to 74.7% by mass of monomer (b), from 0.1% to 10% by mass of monomer (c), from 0.1% to 5% by mass of monomer (d) and from 0.1% to 5% by mass of monomer (e).; 6. Composition according to one of claims 1 to 5 for which the compound F is a compound of formula I in which R represents a linear C6-C4o-alkyl group, preferably a linear C12-C24-alkyl group; or in which x represents a number ranging from 1 to 30, preferably a number ranging from 5 to 25; preferably R represents a linear C6-C4o-alkyl group, preferably a linear C12-C24-alkyl group, and x represents a number ranging from 1 to 30, preferably a number ranging from 5 to 25.

7. Composition according to one of claims 1 to 6 comprising, relative to the mass quantity of the composition: from 0.02% to 2% dry by mass of aqueous rheological agent R; from 30% to 90% dry by mass of particles of mineral material M; from 2% to 25% dry by mass of binding agent L and from 7.98% to 44.98% by mass of water; or for which: the aqueous rheological agent R comprises from 0.05% to 5%, preferably from 0.1% to 2%, by dry mass of compound F, relative to the dry mass quantity of copolymer P.

8. Composition according to one of claims 1 to 7 for which: the particles of mineral material M have a size less than 50 pm or a size ranging from 0.05 pm to 50 pm or a size less than 10 pm, preferably less than 5 pm or 2 pm, more preferably less than 1 pm or less than 0.5 pm; or for which: the equivalent spherical diameter of the particles of mineral material M, for a size ranging from 0.05 pm to 50 pm or less than 50 pm, preferably for a size less than 10 pm, more preferably less than 5 pm or 2 pm, even more preferably less than 1 pm or less than 0.5 pm, is equal to 60% by weight or equal to 70% by weight or even equal to 80% by weight or even equal to 90% by weight; or comprising: - a single mineral material M or two or three mineral materials M are used; or for which: the mineral material M is synthetic or of natural origin, preferably chosen 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, calcium sulfate, barium sulfate, silicas, more preferably calcium carbonate (natural calcium carbonate or precipitated calcium carbonate) or kaolin;or for which: the binding agent L is a natural binding agent such as starch, carboxymethylcellulose (CMC), hydroxyethyl celluloses, polyvinyl alcohol (PVOH), casein, proteins, alginates, or a synthetic binding agent such as a latex, preferably chosen from a styrene-butadiene polymer, a styrene-acrylic polymer, a styrene-acetate polymer; more preferably a styrene-butadiene polymer; or which also comprises at least one adjuvant, in particular at least one adjuvant chosen from dispersing agents, anti-foaming agents, biocidal agents, coloring agents, lubricating agents and optical brightening agents.

9. Method for preparing paper or cardboard comprising the use of an aqueous composition C according to one of claims 1 to 8, preferably this composition C is used during one or more stages of coating the paper or cardboard.

10. Method according to claim 9 wherein: the water retention of composition C, measured according to the method of the description, during the coating of the paper is improved, preferably the water retention of composition C is improved by 50% to 400% by volume compared to the absence of use of copolymer P; or wherein: the Brookfield viscosity of composition C, measured at 100 rpm and at 25°C according to the method of the description, is sufficient and compatible for the coating process and this viscosity is higher than that of the composition free of copolymer P; preferably: the Brookfield viscosity of composition C, measured at 100 rpm and at 25°C according to the method of the description, ranges from 150 mPa.s to 3,500 mPa.s, more preferably from 500 mPa.s to 2,000 mPa.s; or for which: the capillary viscosity of composition C, measured at 1,000,000 s' 1and at 25°C according to the method of the description, ranges from 10 mPa.s to 100 mPa.s, more preferably from 20 mPa.s to 80 mPa.s; or for which: composition C is deposited on the surface of the paper or cardboard during at least one coating step with a deposit, measured after drying, of 5 to 50 g / m 2 , preferably from 8 to 40 g / m 2 , according to the method of description.

11. High gradient viscosity control method, measured at 1,000,000 s' 1 and at 25°C according to the method of the description, of an aqueous paper coating composition C comprising particles of at least one mineral material M, at least one binding agent L and water, comprising the addition to the composition of at least one rheological agent aqueous R comprising: at least one water-soluble copolymer P prepared by polymerization reaction in the presence of at least one compound E chosen from dialkylsulfosuccinate, sodium salt of dialkylsulfosuccinate and their combinations: • at least one compound (a) chosen from methacrylic acid, a methacrylic acid salt, a methacrylic acid oligomer, a methacrylic acid oligomer salt, acrylic acid, an acrylic acid salt, an acrylic acid oligomer, a acrylic acid oligomer salt and combinations thereof; • at least one compound (b) chosen from Ci-Cio-alkyl methacrylate, Ci-Cio-alkyl acrylate, styrene, vinylcaprolactam, vinylacetate and combinations thereof; at least one compound F of formula I: R-(OE) X -OH) in which R represents a linear C6-C4o-alkyl group or a branched C6-C4o-alkyl group, OE represents an ethylene oxy group and x represents a number ranging from 1 to 50.

12. Aqueous rheological agent R combining or comprising: at least one water-soluble copolymer P prepared by polymerization reaction in the presence of at least one compound E chosen from dialkylsulfosuccinate, sodium salt of dialkylsulfosuccinate and their combinations: • at least one compound (a) chosen from methacrylic acid, a methacrylic acid salt, a methacrylic acid oligomer, a methacrylic acid oligomer salt, acrylic acid, an acrylic acid salt, an acrylic acid oligomer, a acrylic acid oligomer salt and combinations thereof; • at least one compound (b) chosen from Ci-Cio-alkyl methacrylate, Ci-Cio-alkyl acrylate, styrene, vinylcaprolactam, vinylacetate and combinations thereof; at least one compound F of formula I: R-(OE) X -OH (J) in which R represents a linear C6-C4o-alkyl group or a group Branched C4O-C6O-alkyl, OE represents an ethylene oxy group and x represents a number ranging from 1 to 50.

13. Aqueous rheological agent R according to claim 12 for which the polymer P and the compound F are defined according to one of claims 2 to 6.

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