COATING SAUCE COMPOSITION

Abstract

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.

Description

Title of the invention: COATING SAUCE COMPOSITION

[0001] 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 dialkylsulfo-succinate 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.

[0002] In addition to improving the final properties of the paper prepared using these coating sauces, it is also necessary to improve the preparation conditions and the conditions for implementing these paper coating sauce compositions.

[0003] In addition, these compositions must have viscosities under different shear gradients which allow them to be used effectively, in particular 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.

[0004] Furthermore, increasing the viscosities under high and low shear gradients 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 in order to avoid a change 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.

[0005] 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.

[0006] The compositions for preparing paper coating sauce comprise insoluble materials, in particular mineral particles. A high concentration and a high dry extract of these compositions are often sought, although by increasing the concentration or the dry extract, the risk of viscosity drift, in particular at high shear gradient, is increased.

[0007] The possibility of effectively implementing very small mineral particles is also sought, in particular to improve the optical properties of paper. However, these very small mineral particles can disrupt the viscosity and stability of paper coating compositions.

[0008] These compositions must also limit or avoid the sedimentation of the particles used. They must also make it possible to limit, or even avoid, the formation of foam or splashes.

[0009] The compatibility of the different constituents of a paper coating sauce must also be taken into account. In particular, it is important to benefit from good compatibility with the latex binder used.

[0010] Thickening copolymers used for the preparation of paper coating sauces as well as rheological adjuvants are known. However, the known rheological agents do not always provide a satisfactory solution to these various problems.

[0011] There is therefore a need for improved rheological agents to provide paper coating compositions.

[0012] 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:

[0013] - at least one aqueous rheological agent R comprising:

[0014] - at least one water-soluble P copolymer prepared by polymerization reaction in presence of at least one compound E chosen from dialkylsulfosuccinate, sodium salt of dialkylsulfosuccinate and their combinations:

[0015] - of at least one compound (a) chosen from methacrylic acid, a salt of metha- acrylic acid, an oligomer of methacrylic acid, a salt of an oligomer of methacrylic acid, acrylic acid, an acrylic acid salt, an oligomer of acrylic acid, a salt of an oligomer of acrylic acid, salts thereof and combinations thereof;

[0016] - of at least one compound (b) chosen from Ci-Ci0-alkyl methacrylate, C acrylate i-Cio-alkyl, styrene, vinylcaprolactam, vinylacetate and combinations thereof;

[0017] - at least one compound F of formula I:

[0018] R-(OE)S-OH

[0019] in which R represents a linear C6-C40-alkyl group or a branched C6-C40-alkyl 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.

[0020] Preferably according to the invention, the composition C according to claim 1 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 C8-Ci6-alkyl group or a group C8-Ci6-branched alkyl, more preferably, the mercaptan compound is selected from tert-nonylmercaptan, tert-dodecylmercaptan, n-dodecylmercaptan and combinations thereof. More preferably, compound E is tert-nonylmercaptan.

[0021] 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.

[0022] 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.

[0023] 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 NaHCO3, 0.1 M NaNO3, 0.02 M triethanolamine and 0.03% NaN3.

[0024] In a first step, the copolymer solution is diluted to 0.9% dry weight 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 NaHCO3, 0.1 M NaNO3, 0.02 M triethanolamine and 0.03% NaN3).

[0025] The liquid chromatography apparatus contains an isocratic pump (“Waters” 515) whose flow rate is set at 0.8 mL / min. The chromatography apparatus also comprises an oven which itself comprises in series the following column system: a precolumn of the “Guard Column Ultrahydrogel Waters” type, 6 cm long and 40 mm internal diameter and a linear column of the “Ultrahydrogel Waters” type, 30 cm long and 7.8 mm internal diameter. The detection system consists of a refractometric detector of the “RI Waters” 410 type. The oven is brought to a temperature of 60°C and the refractometer is brought 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).

[0026] 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 copolymer P is neutralized by means of LiOH, NaOH, KOH, Mg(OH)2, Ca(OH)2, aqueous ammonia and combinations thereof.

[0027] 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.

[0028] 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.

[0029] 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, n-butyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isobutyl methacrylate, n-butyl methacrylate, aryl acrylate, in particular phenylacrylate, benzyl acrylate, phenoxyethyl acrylate, aryl methacrylate, in particular preferably phenyl methacrylate, benzyl methacrylate, phenoxyethyl methacrylate and combinations thereof. Much more preferably, it is chosen from methyl acrylate, ethyl acrylate, isobutyl acrylate, n-butyl acrylate, methyl methacrylate, even more preferably from methyl acrylate and ethyl acrylate.

[0030] In addition to the monomers (a) and (b), the polymer P can also be prepared using one or more other monomers. Then, preferably according to the invention, the copolymer P can be prepared by a polymerization reaction also using at least one compound (c) of formula II: [003 i] RiqoEMÛPk-R2

[0032] 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;

[0033]

[0034]

[0035]

[0036]

[0037]

[0038] - R1 represents 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; - R2 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-C40-alkyl group, preferably a linear or branched C8-C30-alkyl group, a C6-C4o-aryl group, preferably a C8-C30-aryl group, for example a tristy-rylphenyl group. 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. 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; - OE represents an oxyethylene group; - R1 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; - R2 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-C40-alkyl group, preferably a linear or branched C8-C30-alkyl group, a C6-C40-aryl group, preferably a C8-C30-aryl group, for example a tristy-rylphenyl group. According to the invention, the polymerization reaction can 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 allyl-polyethylenepolypropylene glycol, - methallylpolyalkylene glycol, preferably among methallylpolyethylè- neglycol and methallylpolyethylenepolypropylene glycol, - 3-methyl-3-buten-l-ylpolyalkylene glycol, preferably from 3-methyl-3-buten-1-ylpolyethylene glycol and 3-methyl-3-buten-1-ylpolyethylenepolypropylene glycol.

[0039] 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).

[0040] 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.

[0041] 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).

[0042] 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-C40-alkyl group, preferably a linear C12-C24-alkyl group.

[0043] 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-C40-alkyl group, preferably a linear C12-C24-alkyl group, and x represents a number ranging from 1 to 30.

[0044] More preferably according to the invention, the 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-C40-alkyl group, preferably a linear C12-C24-alkyl group, and x represents a number ranging from 5 to 25.

[0045] 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.

[0046] 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 quantities 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:

[0047] - 0.02% to 2% dry by mass of aqueous rheological agent R;

[0048] - 30% to 90% dry mass of particles of mineral material M;

[0049] - 2% to 25% dry mass of binding agent L and

[0050] - 7.98% to 44.98% by mass of water.

[0051] 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 μm or a size ranging from 0.05 μm to 50 μm or a size of less than 10 μm, preferably less than 5 μm or 2 μm, more preferably less than 1 μm or less than 0.5 μm.

[0052] Also preferably according to the invention, the particles of mineral material M have a spherical equivalent diameter, for a size ranging from 0.05 μm to 50 μm 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 60% by weight or equal to 70% by weight.

[0053] More preferably according to the invention, the particles of mineral material M have a spherical equivalent diameter, for a size ranging from 0.05 μm to 50 μm or less than 50 μm, preferably for a size less than 10 μm, more preferably less than 5 μm or 2 μm, even more preferably less than 1 μm or less than 0.5 μm, which is equal to 80% by weight or even equal to 90% by weight.

[0054] 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.

[0055] 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.

[0056] Preferably according to the invention, 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. 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.

[0057] 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.

[0058] Composition C according to the invention has several advantageous properties. These properties are particularly effective during 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.

[0059] The paper coating sauces prepared according to the invention are particularly advantageous when preparing a primary coating layer (pre-coat) or when preparing a final paper coating layer (top-coat) or even a simple layer.

[0060] Furthermore, 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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 / m2, more preferably of 8 to 40 g / m2, measured according to the method of the examples.

[0065] The deposition can be carried out by a blade or pencil coating process, by a film transfer press, an air knife, a size press or curtain coating.

[0066] Essentially according to the invention, the aqueous paper coating composition C comprises the aqueous rheological agent R giving it numerous properties sought 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 material mineral M, at least one binding agent L and water, comprising the addition to the composition of at least one aqueous rheological agent R comprising:

[0067] - at least one water-soluble P copolymer prepared by polymerization reaction in presence of at least one compound E chosen from dialkylsulfosuccinate, sodium salt of dialkylsulfosuccinate and their combinations:

[0068] - of at least one compound (a) chosen from methacrylic acid, a salt of metha- acrylic acid, an oligomer of methacrylic acid, a salt of an oligomer of methacrylic acid, acrylic acid, an acrylic acid salt, an oligomer of acrylic acid, a salt of an oligomer of acrylic acid and combinations thereof;

[0069] - of at least one compound (b) chosen from Ci-Ci0-alkyl methacrylate, C acrylate i-Cio-alkyl, styrene, vinylcaprolactam, vinylacetate and combinations thereof;

[0070] - at least one compound F of formula I:

[0071] R-(OE)X-OH

[0072] in which R represents a linear C6-C40-alkyl group or a branched C6-C40-alkyl group and x represents a number ranging from 1 to 50.

[0073] 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.

[0074] The invention therefore also provides an aqueous rheological agent R combining:

[0075] - at least one water-soluble P copolymer prepared by polymerization reaction in presence of at least one compound E chosen from dialkylsulfosuccinate, sodium salt of dialkylsulfosuccinate and their combinations:

[0076] - of at least one compound (a) chosen from methacrylic acid, a salt of methacrylic acid acrylic acid, an oligomer of methacrylic acid, a salt of an oligomer of methacrylic acid, acrylic acid, an acrylic acid salt, an oligomer of acrylic acid, a salt of an oligomer of acrylic acid and combinations thereof;

[0077] - of at least one compound (b) chosen from Ci-Ci0-alkyl methacrylate, Ci-Cio acrylate - alkyl, styrene, vinylcaprolactam, vinylacetate and combinations thereof;

[0078] - at least one compound F of formula I:

[0079] R-(OE)X-OH

[0080] in which R represents a linear C6-C40-alkyl group or a branched C6-C4o-alkyl group and x represents a number ranging from 1 to 50.

[0081] According to the invention, the agent R can be prepared beforehand. Thus, the invention also provides an aqueous rheological agent R comprising:

[0082] - at least one water-soluble P copolymer prepared by polymerization reaction in presence of at least one compound E chosen from dialkylsulfosuccinate, sodium salt of dialkylsulfosuccinate and their combinations:

[0083] - of at least one compound (a) chosen from methacrylic acid, a salt of metha- acrylic acid, an oligomer of methacrylic acid, a salt of an oligomer of methacrylic acid, acrylic acid, an acrylic acid salt, an oligomer of acrylic acid, a salt of an oligomer of acrylic acid and combinations thereof;

[0084] - of at least one compound (b) chosen from Ci-Ci0-alkyl methacrylate, Ci-Cio acrylate - alkyl, styrene, vinylcaprolactam, vinylacetate and combinations thereof;

[0085] - at least one compound F of formula I:

[0086] R-(OE)X-OH

[0087] in which R represents a linear C6-C40-alkyl group or a branched C6-C40-alkyl group and x represents a number ranging from 1 to 50.

[0088] Preferably according to the invention, the aqueous rheological agent R comprises a polymer P and a compound F defined according to the invention.

[0089] 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.

[0090] The following examples illustrate the different aspects of the invention, in particular the preparation and characterization of paper coating compositions according to the invention.

[0091] Preparation of polymers PI and P2 according to the invention and of rheological agents RI and R2 according to the invention:

[0092] The following compounds are used: • compound (a), AMA: methacrylic acid, • compound (b), AE: ethyl acrylate, • compound E, DOS: dioctylsulfosuccinate 50% solution in water, • tert-nonyl mercaptan, • sodium persulfate, (NH4)2S2O8, • sodium metabisulfite, Na2S2O5, • compound F, Genapol T200 Clariant: n-Ci6-Ci8-alkyl methacrylate ethoxylated 20 times.

[0093] 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, • a 50% aqueous solution of dioctylsulfosuccinate, • transfer agent, tert-nonyl mercaptan.

[0094] An initiator solution comprising ammonium persulfate, deionized water and sodium metabisulfite is prepared. 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.

[0095] [tab 1] quantity (g) PI and RI P2 and R2 mixture 1 deionized water 460.9 460.9 DOS 9.57 9.57 mixture 2 deionized water 137 137 DOS 1.45 1.45 AMA (a) 108.5 108.5 AE(b) 185 185 tert-nonyl mercaptan 0.3 0 initiator deionized water 9.7 9.7 ammonium persulfate 0.902 0.902 sodium metabisulfite 0.09 0.09 polymer composition monomer (a) (% by mass) 37 37 monomer (b) (% by mass) 63 63 compound F (g / 100 g of dry polymer) 0.26 0.26 mercaptan (ppm / quantity of monomers) 1 000 0 characteristics final dry extract (% by weight) 30.1 30.2

[0096] Preparation and characterization of compositions C1 and C2 according to the invention:

[0097] The pH is measured at 25°C with a pH meter (WTW) equipped with a conventional electrode coupled to a temperature probe.

[0098] The dry extract is measured dry using a microwave balance (CEM). A determined mass of between 1 and 4 g of composition is placed on sandpaper. Then, the The scale dries this mass using microwaves. The scale stops drying when the weight has not changed for 10 seconds. The difference in weight is expressed as a %; this determines the dry extract.

[0099] 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 considered in order to be within the optimal operating range of the rheometer.

[0100] The capillary viscosity at 25°C and at 106 s 1 is measured using a capillary viscometer (ACAV A2 ACA).

[0101] Water retention is determined at 25°C (AAGWR Gradek) which comprises 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 apparatus makes it possible to exert pressure (1.5 bar) 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 s. 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 increase in water retention is equal to 1250 x (PI - PO) / PO.

[0102] 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 brightening agent (“Blankophor 4900”) are mixed with stirring.

[0103] 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 *.

[0104] Composition C1 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 C1 according to the invention are measured:

[0105] - Brookfield viscosity at 100 rpm: 1,000 mPa.s,

[0106] - water retention: 210 g / m2,

[0107] - capillary viscosity: 65 mPa.s.

[0108] Similarly, composition C2 according to the invention is prepared and characterized using 0.2 parts by mass of agent R2:

[0109] - Brookfield viscosity at 100 rpm: 1,000 mPa.s,

[0110] - water retention: 185 g / m2, [YES] - capillary viscosity: 65 mPa.s.

[0112] The agents RI and R2 combining the compound F and, respectively, the polymers PI and P2 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.

[0113] Agents RI and R2 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 dialkyl-sulfosuccinate, 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, a acrylic acid salt, an acrylic acid oligomer, a acrylic acid oligomer salt, their salts and their combinations; - at least one compound (b) chosen from Ci-Ci0-alkyl methacrylate, Ci-Ci0-alkyl acrylate, styrene, vinylcaprolactam, vinyl acetate and combinations thereof; - at least one compound F of formula I: R-(OE)X-OH in which R represents a linear C6-C40-alkyl group or a branched C6-C40-alkyl 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 combinations thereof, optionally combined with at least one mercaptan compound, preferably a mercaptan compound comprising a linear C8-Ci6-alkyl group or a branched C8-Ci6-alkyl group, more preferably a mercaptan compound chosen from / e / 7-nonyl mercaptan, tert-docecylmercaptan, n-dodecylmercaptan and combinations thereof; 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; preferentially from methyl acrylate, ethyl acrylate, propyl acrylate, isobutyl acrylate, n-butyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isobutyl methacrylate, n-butyl methacrylate, aryl acrylate, in particular phenylacrylate, benzyl acrylate, phenoxyethyl acrylate, aryl methacrylate, in particular preferably phenyl methacrylate, benzyl methacrylate, phenoxyethyl methacrylate and combinations thereof; more preferentially chosen from methyl acrylate, ethyl acrylate, isobutyl acrylate, n-butyl acrylate, methyl methacrylate, much more preferentially 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: R1 -(OE)æ4 OP L-JC 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, - R1 represents a group comprising at least one polymerizable olefinic unsaturation, preferably a group chosen from acrylate, methacrylate, acry-lurethane, methacrylurethane, vinyl, allyl, methallyl and isoprenyl; more preferably a methacrylate group, - R2 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 C8-C30-alkyl group, a C6-C^-aryl group, preferably a C8-C3o-aryl group, for example a tristy-rylphenyl 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 polyethylene polypropylene glycol methacrylate, - allylpolyalkylene glycol, preferably from allylpolyethylene glycol and allylpolyethylenepolypropylene glycol, - methallylpolyalkylene glycol, preferably among methallyl-

5. polyethylene glycol and methallylpolyethylenepolypropylene glycol, - 3-methyl-3-buten-l-ylpolyalkylene glycol, preferably from 3-methyl-3-buten-l-ylpolyethylene glycol and 3-methyl-3-buten-l-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% in mass of monomer (e).

6. 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-C40-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-C40-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. 7. Composition according to one of claims 1 to 6 comprising, relative to the mass quantity of the composition: - 0.02% to 2% dry by mass of aqueous rheological agent R; - 30% to 90% dry by mass of particles of mineral material M; - 2% to 25% dry by mass of binding agent L and - 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. 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;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, carbonate of; magnesium, 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), hydroxyethylcelluloses, 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. 10. Method according to claim 9 for which: - the water retention of composition C, measured according to the method of the description, during 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 for which: - 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 rnPa.s to 3,500 rnPa.s, more preferably from 500 rnPa.s to 2,000 rnPa.s; or for which - the capillary viscosity of composition C, measured at 1,000,000 s 1 and at 25°C according to the method of the description, ranges from 10 rnPa.s to 100 rnPa.s, more preferably from 20 rnPa.s to 80 rnPa.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 / m2, preferably of 8 to 40 g / m2, depending on the description method.

11. 11. Method for controlling high gradient viscosity, measured at 1,000,000 s 1 and at 25°C according to the method of the description, of an aqueous composition C of paper coating 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 dialkyl-sulfosuccinate, 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, vinyl acetate and combinations thereof; - at least one compound F of formula I: R-(OE)X-OH in which R represents a linear C6-C40-alkyl group or a branched C6-C40-alkyl 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-Ci0-alkyl methacrylate, Ci-Ci0-alkyl acrylate, styrene, vinylcaprolactam, vinyl acetate and combinations thereof; - at least one compound F of formula I: R-(OEX-OH in which R represents a linear Ce-C^-alkyl group or a branched Ce-C^-alkyl 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.