19sodium dodecyl sulphateare placed.In a first glass beaker, 116.04 g of monomer (a1-2) according to the proportions shown in table 2, 198.55 g of ethyl acrylate (a2), 1.12 g of sodium dodecyl sulphate and 161.01 g of deionised waterare weighed.In a second glass beaker, 0.979 g of ammonium persulphate is weighed and then dissolved5in 5 g of deionised water.In a third glass beaker, 0.098 g of sodium metabisulphite is weighed and then dissolvedin 2 g of deionised water. In a disposable syringe, 11.4 g of 2-acrylamido-2-methylpropane sulphonic acid sodium salt (a3) at 50% by weight in waterare weighed.10Heat the reactor content to 76°C ± 2°C.Inject the reagents from the 4 containers into the polymerisation reactor over two hours at a temperature of 76°C ± 2°C.0.114 g of ammonium persulphate dissolved in 20 g of deionised waterare then added, over 1 hour, keeping the temperature at 76°C ± 2°C. To finish, bake for 1 hour before 15allowing the medium to cool and then filtering it. No scaling appears when preparing the copolymer.A comparative copolymer (PC3) was obtained at 31.0% by weight of solids content, of which the composition is detailedin table 2.AA: acrylic acidMAA: methacrylic acid EA: ethyl acrylate20Table 2Example 3: preparation and characterisation of paper coating colours according to the invention and comparativesThe polymers according to the invention and polymers from the prior art were usedin combination with the following products in theaqueous compositions for paper coating 25colours:Comparative CopolymerMonomer (quantity -% by weight)(a1)(a2)(a3)(a4)PC1AA (10.00)MAA (35.70)EA(49.90)-C16-OE25Guerbet alcohol methacrylate (4.40)PC2AA (10.00)MAA (35.70)EA(49.90)-C16-OE25Guerbet alcohol methacrylate (4.40)PC3MAA (36.22)EA(62.00)AMPS (1.78)-
20-CaCO3pigment as mineral material: Hydrocarb 60, Hydrocarb 90 or Hydrocarb 95 products (Omya), at 78% by weight in water,-binding agent: DL 1066 latex (Trinseo), at 55% by weight in water,-binding agent: Stabilys A30 starch (Rocquette), at 25% by weight in water,-polyvinyl alcohol as an optical brightener: (PV-OH) Mowiol 4-98 (Chang Chung 5Petrochemical), at 25% by weight in water.The proportions (in g, dry for dry) of the constituents of the compositions for paper coating colours are shown in table 3.The solidscontent of the paper coating coloursaremeasured dry using a CEM microwave scales. A piece of sandpaper iscoated with paper coating colourat a mass determined10between 1 and 4 g. Then it isdried in the microwave scales.The scales stop drying when the weight no longer changes for 10 sec. The weight difference is expressed in %, which determines the solidscontent.The pH ismeasured at 25°C using a WTW pH-meter with a conventional electrode coupled to a temperature probe.15The Brookfield viscosity of the compositions prepared ismeasured at 100 rpm at 25°C using an analogue viscosity meter. The spindle ischosen according to the viscosity of the composition studied so as to be within the optimal use range of the rheometer.ACAV capillary viscosity at 106s-1ismeasured using an ACAV A2 capillary meter by ACA.20Water retention isdetermined with a Gradek AAGWR apparatus. This has a measuring chamber in which is placed a test paper (Blotter Paper Gradek Test)covered by a perforated plastic sheet (2 μm Gradek PCTE test filter). 10 mL of the paper coating colouris then placed in the chamber. The AAGWR apparatus allows pressure (1.5 bar) to be applied to the paper coating colour, which causes all or part of the water and the 25water-soluble substances in the coating to pass through the perforated plastic sheet andmigrate into the test paper. A pressure of 1.5 bar is applied for 90 sec. The difference between the weight of the test paper before measuring (P0) and after measuring (P1) gives the amount of water and water-soluble substances in the paper coating colourthat migrated into the test paper during the measurement. The relative value of the increase in water 30retention is 1,250 x (P1 -P0) / P0. The results obtained are shown in table 3.
21Table 3With respect to the comparative composition (CC1) which does not comprise a thickening agent, it was found that the presence of a small amount of polymer (P1) in the composition (C1) according to the invention makes it possible to control the viscosity at a high shear gradient as well as at a low shear gradient. The polymer (P1) also provides a good water 5retention to the paper coating colour.With respect to the comparative composition (CC2) which comprises a thickening agent prepared from methacrylic acidand without acrylic acid, the presence of polymers (P2) and (P3) also makes it possible to improve these properties.With respect to the comparative composition (CC3) which does not comprise a thickening 10agent, the presence of polymers (P6) and (P7) also makes it possible to provide good properties.Compositionaccording to the inventionComparativeC1C2C3C4C5CC1CC2CC3(a) polymer P10.12(a) polymer P20.4(a) polymer P30.4(a) polymer P60.2(a) polymer P70.2polymer PC30.4(b) Hydrocarb 60100100(b) Hydrocarb 90100100202010020(b) Hydrocarb 95808080(c) DL 1066 latex78877787(c) Stabilys A30111Mowiol PV-OH 4/9810.50.510.5Solidscontent (% by weight)71636367.167.1716367.1pH after addition of NaOH 12.5% by weight in water9.28.58.58.88.89.28.58.8Brookfield viscosity @ 100 rpm (mPa.s)7101,2701,1402,5152,2302851,110380Acav HSV viscosity @ 106s-1(mPa.s)12679768253AAGWR water retention (2μm-1.5b-90s) (g/m²)113787811010735088211
22CLAIMS1.An aqueous composition for preparing a paper coating colourcomprising:a)at least one copolymer prepared by polymerisation reaction:(a1) of at least one compound (a1) chosenamong:5-at least one compound (a1-1) chosenamong acrylic acid alone, an acrylic acid salt alone and combinations thereof and-at least one compound (a1-1) combined with a compound (a1-2) chosenamong methacrylic acid, a methacrylic acid salt and combinations thereof, in an (a1-1) / (a1-2) weight ratio greater than 0.15,10(a2) of at least one ester of an acid (a2) chosenamong acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, maleic anhydride and(a3) of at least one compound (a3) chosenamong 2-acrylamido-2-methylpropane sulphonic acid, 2-sulphoethyl methacrylate, sodium methallyl sulphonate, styrene sulphonate, their salts and combinations 15thereof,b)at least one mineral materialin particle form,c)at least one binding agent andd)water.202.The composition according to claim 1, wherein:-the monomer (a1) is the only monomer (a1-1), preferably the only acrylic acid or-the monomer (a1-1) is acrylic acid or-the monomer (a1-2) is methacrylic acid or-the (a1-1) / (a1-2) weight ratio is greater than 0.2 or 0.5, preferably greater than 1 25or 2, more preferentially greater than 5 or 8, even more preferentially greater than 10 or 15, much more preferentially greater than 20 or 35, also more preferentially greater than 50 or 80 or-the (a1-1) / (a1-2) weight ratio ranges from 0.2 to 80, preferably from 0.5 to 50, more preferentially from 1 to 35, much more preferentially from 2 to 20, even more 30preferentially from 5 to 15 or from 8 to 10 or-the monomer (a2) is chosenamong styrene, vinyl caprolactam, alkyl acrylate, in particular C1-C10alkyl acrylate, preferentially C1-C4alkyl acrylate, more
23preferentially methyl acrylate, ethyl acrylate, propyl acrylate, isobutyl acrylate, n-butyl acrylate, alkyl methacrylate, particularly C1-C10alkyl methacrylate, preferentially C1-C4alkyl methacrylate, more preferentially methyl methacrylate, ethyl methacrylate, propyl methacrylate, isobutyl methacrylate, n-butyl methacrylate, aryl acrylate, preferably phenyl acrylate, benzyl acrylate, 5phenoxyethyl acrylate, aryl methacrylate, preferably phenyl methacrylate, benzyl methacrylate, phenoxyethyl methacrylate and combinations thereof, preferably methyl acrylate, ethyl acrylate, isobutyl acrylate, n-butyl acrylate, methyl methacrylate, more preferentially methyl acrylate or ethyl acrylate or-the monomer (a3) is 2-acrylamido-2-methylpropane sulphonic acid.103.The composition according to one of claims 1 or 2, wherein the copolymer (a) is prepared by polymerisation reaction which also uses:(a4) at least one compound of formula (I):R1-(EO)m-(PO)n-R2(I)15wherein:-m and n, identical or different, independently represent 0 or an integer or decimal less than 150, m or n is different from 0,-EOrepresents a CH2CH2O group,-POindependently represents a group chosen among CH(CH3)CH2O and 20CH2CH(CH3)O,-R1represents a group comprising at least one polymerisable olefinic unsaturation, preferably a group chosenamong acrylate, methacrylate, acryl urethane, methacryl urethane, vinyl, allyl, methallyl and isoprenyl, more preferentially a methacrylate group,25-R2represents a straight, branched or cyclical, saturated, unsaturated or aromatic hydrocarbon group comprising from 6 to 40 carbon atoms, preferably a C6-C40alkyl group, straightor branched, preferably a C8-C30alkyl group, straight or branched, a C6-C40aryl group, preferably a C8-C30aryl group such as a tristyryl phenyl group or30(a5) at least one monomer chosenamong:-polyalkyleneglycol acrylate, preferably polyethylene glycol acrylate or polyethylene-polypropylene glycol acrylate,
24-polyalkylene glycol methacrylate, preferably polyethylene glycol methacrylate or polyethylene-polypropylene glycol methacrylate, -allyl polyalkylene glycol, preferably allyl polyethylene glycol or allyl polyethylene-polypropylene glycol,-methallyl polyalkylene glycol, preferably methallyl polyethylene 5glycol or methallyl polyethylene-polypropylene glycol,-3-methyl-3-buten-1-ylpolyalkylene glycol, preferably 3-methyl-3-buten-1-ylpolyethylene glycol or 3-methyl-3-buten-1-ylpolyethylene-polypropylene glycol or(a6) at least one cross-linking monomer or at least one monomer comprising 10at least two olefinic unsaturations.4.The composition according to one of claims 1 to 3, wherein:-the amount by mass of the monomer (a1-1) is greater than the amount by mass of the monomer (a1-2); preferably the amount by mass of the monomer (a1-1) is at 15least 1.5 times, 2 times, 3 times, 4 times, 5 times, 8 times, 10 times greater than the amount by mass of the monomer (a1-2) or-the monomer (a4) is a compound of formula (I) in which:om represents an integer or decimal ranging from 20 to 40 and n is null, orom and nindependently represent an integer or decimal ranging from 5 to 20100 orothe mass ratio m/n ranges from 90/10 to 70/30.5.The composition according to one of claims 1 to 4, wherein the copolymer comprises:-from 20 to 69% by mass of monomer (a1),25-from 30 to 79% by mass of monomer (a2) and-from 1 to 5% by mass of monomer (a3).6.The composition according to one of claims 3 to 5, wherein the copolymer comprises:-from 20 to 69% by mass of monomer (a1),30-from 29.5 to 78.5% by mass of monomer (a2),-from 1 to 5% by mass of monomer (a3) and-from 0.5 to 30% by mass of monomer (a4).
257.The composition according to one of claims 3 to 6, wherein the copolymer comprises:-from 20 to 69% by mass of monomer (a1),-from 29.5 to 78.5% by mass of monomer (a2),-from 1 to 5%by mass of monomer (a3) and5-from 0.5 to 30% by mass of monomer (a5).8.The composition according to one of claims 3 to 7, wherein the copolymer comprises:-from 19.9 to 68.9% by mass of monomer (a1),-from 30 to 79% by mass of monomer (a2),10-from 1 to 5% by mass of monomer (a3) and-from 0.1 to 5% by mass of monomer (a6).9.The composition according to one of claims 3 to 8, wherein the copolymer comprises:-from 15 to 69% by mass of monomer (a1),15-from 29 to 83% by mass of monomer (a2),-from 1 to 5% by massof monomer (a3),-from 0.5 to 30% by mass of monomer (a4) and-from 0.5 to 30% by mass of monomer (a5).2010.The composition according to one of claims 3 to 9, wherein the copolymer comprises:-from 19.9 to 68.9% by mass of monomer (a1),-from 29.5 to 78.5% by mass of monomer (a2),-from 1 to 5% by mass of monomer (a3),-from 0.5 to 30% by mass of monomer (a4) and25-from 0.1 to 5% by mass of monomer (a6).11.The composition according to one of claims 3 to 10, wherein the copolymer comprises:-from 19.9 to 68.9% by mass of monomer (a1),-from 29.5 to 78.5% by mass of monomer (a2),30-from 1 to 5% by mass of monomer (a3),-from 0.5 to 30% by mass of monomer (a5) and-from 0.1 to 5% by mass of monomer (a6).
2612.The composition according to one of claims 3 to 11, wherein the copolymer comprises:-from 19.9 to 68.9% by mass of monomer (a1),-from 29 to 78% by mass of monomer (a2),-from 1 to 5% by mass of monomer (a3),5-from 0.5 to 30% by mass of monomer (a4),-from 0.5 to 30% by mass of monomer (a5) and-from 0.1 to 5% by mass of monomer (a6).13.The composition according to one of claims 1 to 12, wherein:10-the particles of mineral materialhave 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 preferentially less than 1 μm or less than 0.5 μm or -the equivalent spherical diameter of the particles of mineral material, for a size ranging from 0.05 μm to 50 μm or less than 50 μm, preferably for a size of less 15than 10 μm, more preferentially less than 5 μm or 2 μm, even more preferentially less than 1 μm or less than 0.5 μm, 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.14.The composition according to one of claims 1 to 13,wherein:20-a single mineral material(b) or two or three mineral materials (b) are usedor -the mineral material(b) is of synthetic or natural origin, preferably chosenamong the alkaline-earth metal carbonates, preferably calcium carbonate (natural calcium carbonate or precipitated calcium carbonate), strontium carbonate, magnesium carbonate, barium carbonate, dolomite, kaolin, titanium dioxide, talcum, lime, 25calcium sulphate, barium sulphate, silica, more preferentially calcium carbonate (natural calcium carbonate or precipitated calcium carbonate) or kaolin.15.The composition according to one of claims 1 to 14, wherein the binding agent (c) is a natural binding agent such as starch, carboxymethyl cellulose (CMC), hydroxyethyl 30celluloses, polyvinyl alcohol (PV-OH), casein, proteins, alginates, or a synthetic binding agent such as latex, preferably chosen from a styrene-butadiene polymer, a styrene-acrylic polymer, a styrene-acetate polymer, more preferentially a styrene-butadiene polymer.
2716.The composition according to any of claims 1 to 15, comprising:-from0.02 to 2% by dry mass of copolymer (a),-from 30 to 75% by dry mass of mineral material (b),-from 2 to 25% by dry mass of binding agent (c) and5-from 22.98 to 44.98% by mass of water.17.Thecomposition according to any of claims 1 to 16, also comprising at least oneadmixture, in particular at least oneadmixture chosen among dispersing agents, anti-foaming agents, biocides, colouring agents, lubricants and optical brighteners.1018.A method of paper or cardboard preparation comprising the use of an aqueous composition according to one of claims 1 to 17; preferably, this composition is usedduring one or more of the paper or cardboard coating steps.1519.The method according to claim 18,wherein the water retention of the composition during the paper coating step is improved; preferably, the composition’s water retention is improved from 50 to 400% by volume compared to when no copolymer (a) is used.20.The method according to one of claims 18 or 19, wherein the composition has a low 20shear viscosity (Brookfield viscosity at 100 rpm) that is sufficient and compatible with the coating process and superior to the composition which does not use the copolymer; preferably, the viscosity under low shear ranges from 150 to 3,500 mPa.s (Brookfield viscosity at 100 rpm).2521.The method according to one of claims 18 to 20, wherein the composition is deposited on the surface of the paper or cardboard in at least one coating step with a coat weight, after drying, of from 5 to 50 g/m², preferentially from 8 to 40 g/m²