Composition for paper coating slip

Abstract

The invention relates to a paper coating slip composition comprising a copolymer of thickening acrylic acid, a mineral material in the form of particles, a binding agent, and water. The invention also relates to the use of said composition for the production of paper or cardboard, improving the water retention of the paper coating slip.

Claims

1. An aqueous composition, comprising: a) from 0.02 to 2% by dry mass of at least one copolymer prepared by a polymerisation reaction comprising: at least one compound (a1) selected from the group consisting of: at least one compound (a1-1) selected from the group consisting of acrylic acid, an acrylic acid salt and combinations thereof; and at least one compound (a1-2) selected from the group consisting of methacrylic acid, a methacrylic acid salt and combinations thereof, in an (a1-1)/(a1-2) weight ratio of greater than 0.15; at least one compound (a2) selected from the group consisting of styrene, vinyl caprolactam, an ester of acrylic acid, an ester of methacrylic acid, an ester of itaconic acid, an ester of crotonic acid, an ester of maleic acid, an ester of maleic anhydride, and combinations thereof; and at least one compound (a3) selected from the group consisting of 2-acrylamido-2-methylpropane sulphonic acid, 2-sulphoethyl methacrylate, sodium methallyl sulphonate, styrene sulphonate, salts thereof and combinations thereof, b) from 30 to 75% by dry mass of at least one mineral material selected from the group consisting of an alkaline-earth carbonate, dolomite, kaolin, titanium dioxide and talcum in particle form, c) from 2 to 25% by dry mass of at least one binding agent, and d) 22.98 to 44.98% by mass of water.

2. The aqueous composition of claim 1, wherein: (a1) is (a1-1), or (a1-1) is acrylic acid, or (a1-2) is methacrylic acid, or the (a1-1)/(a1-2) weight ratio is greater than 0.2, or (a2) is alkyl acrylate or (a3) is 2-acrylamido-2-methylpropane sulphonic acid.

3. The aqueous composition of claim 1, wherein the polymerisation reaction further comprises: (a4) at least one compound of formula (I):
R.sup.1-(EO).sub.m—(PO).sub.n—R.sup.2  (I) wherein: m and n, identical or different, independently represent 0 or an integer or decimal less than 150, and m or n is not 0, EO represents a CH.sub.2CH.sub.2O group, each PO independently represents a group selected from the group consisting of CH(CH.sub.3)CH.sub.2O and CH.sub.2CH(CH.sub.3)O, R.sup.1 represents a group comprising at least one polymerisable olefinic unsaturation, and R.sup.2 represents a straight, branched or cyclical, saturated, unsaturated or aromatic hydrocarbon group comprising from 6 to 40 carbon atoms; or (a5) at least one monomer selected from the group consisting of polyalkylene glycol acrylate, polyalkylene glycol methacrylate, allyl polyalkylene glycol, methallyl polyalkylene glycol and 3-methyl-3-buten-1-ylpolyalkylene glycol; or (a6) at least one cross-linking monomer or at least one monomer comprising at least two olefinic unsaturations.

4. The aqueous composition of claim 1, wherein: an amount by mass of (a1-1) is greater than an amount by mass of (a1-2); or the polymerisation reaction further comprises a compound (a4) of formula (I):
R.sup.1-(EO).sub.m—(PO).sub.n—R.sup.2  (I) wherein: EO represents a CH.sub.2CH.sub.2O group, each PO independently represents a group selected from the group consisting of CH(CH.sub.3)CH.sub.2O and CH.sub.2CH(CH.sub.3)O, R.sup.1 represents a group comprising at least one polymerisable olefinic unsaturation, R.sup.2 represents a straight, branched or cyclical, saturated, unsaturated or aromatic hydrocarbon group comprising from 6 to 40 carbon atoms and m represents an integer or decimal ranging from 20 to 40 and n is null, or m and n independently represent an integer or decimal ranging from 5 to 100 or a mass ratio (EO).sub.m/(PO).sub.n ranges from 90/10 to 70/30.

5. The aqueous composition of claim 1, wherein the at least one copolymer comprises: from 20 to 69% by mass of (a1), from 30 to 79% by mass of (a2) and from 1 to 5% by mass of (a3).

6. The aqueous composition of claim 1, wherein: the polymerisation reaction further comprises at least one compound (a4) of formula (I):
R.sup.1-(EO).sub.m—(PO).sub.n—R.sup.2  (I) wherein: m and n, identical or different, independently represent 0 or an integer or decimal less than 150, and m or n is not 0, EO represents a CH.sub.2CH.sub.2O group, each PO independently represents a group selected from the group consisting of CH(CH.sub.3)CH.sub.2O and CH.sub.2CH(CH.sub.3)O, R.sup.1 represents a group comprising at least one polymerisable olefinic unsaturation, and R.sup.2 represents a straight, branched or cyclical, saturated, unsaturated or aromatic hydrocarbon group comprising from 6 to 40 carbon atoms; and the at least one copolymer comprises: from 20 to 69% by mass of (a1), from 29.5 to 78.5% by mass of (a2), from 1 to 5% by mass of (a3) and from 0.5 to 30% by mass of (a4).

7. The aqueous composition of claim 1, wherein: the polymerisation reaction further comprises at least one monomer (a5) selected from the group consisting of polyalkylene glycol acrylate, polyalkylene glycol methacrylate, allyl polyalkylene glycol, methallyl polyalkylene glycol and 3-methyl-3-buten-1-ylpolyalkylene glycol; and the at least one copolymer comprises: from 20 to 69% by mass of (a1), from 29.5 to 78.5% by mass of (a2), from 1 to 5% by mass of (a3) and from 0.5 to 30% by mass of (a5).

8. The aqueous composition of claim 1, wherein: the polymerisation reaction further comprises at least one cross-linking monomer or at least one monomer comprising at least two olefinic unsaturations (a6); and the at least one copolymer comprises: from 19.9 to 68.9% by mass of (a1), from 30 to 79% by mass of (a2), from 1 to 5% by mass of (a3) and from 0.1 to 5% by mass of (a6).

9. The aqueous composition of claim 1, wherein: the polymerisation reaction further comprises: at least one compound (a4) of formula (I):
R.sup.1-(EO).sub.m—(PO).sub.n—R.sup.2  (I) wherein: m and n, identical or different, independently represent 0 or an integer or decimal less than 150, and m or n is not 0, EO represents a CH.sub.2CH.sub.2O group, each PO independently represents a group selected from the group consisting of CH(CH.sub.3)CH.sub.2O and CH.sub.2CH(CH.sub.3)O, R.sup.1 represents a group comprising at least one polymerisable olefinic unsaturation, and R.sup.2 represents a straight, branched or cyclical, saturated, unsaturated or aromatic hydrocarbon group comprising from 6 to 40 carbon atoms, and at least one monomer (a5) selected from the group consisting of polyalkylene glycol acrylate, polyalkylene glycol methacrylate, allyl polyalkylene glycol, methallyl polyalkylene glycol and 3-methyl-3-buten-1-ylpolyalkylene glycol; and the at least one copolymer comprises: from 15 to 69% by mass of (a1), from 29 to 83% by mass of (a2), from 1 to 5% by mass of (a3), from 0.5 to 30% by mass of (a4) and from 0.5 to 30% by mass of (a5).

10. The aqueous composition of claim 1, wherein: the polymerisation reaction further comprises: at least one compound (a4) of formula (I):
R.sup.1-(EO).sub.m—(PO).sub.n—R.sup.2  (I) wherein: m and n, identical or different, independently represent 0 or an integer or decimal less than 150, and m or n is not 0, EO represents a CH.sub.2CH.sub.2O group, each PO independently represents a group selected from the group consisting of CH(CH.sub.3)CH.sub.2O and CH.sub.2CH(CH.sub.3)O, R.sup.1 represents a group comprising at least one polymerisable olefinic unsaturation, and R.sup.2 represents a straight, branched or cyclical, saturated, unsaturated or aromatic hydrocarbon group comprising from 6 to 40 carbon atoms, and at least one cross-linking monomer or at least one monomer comprising at least two olefinic unsaturations (a6); and the at least one copolymer comprises: from 19.9 to 68.9% by mass of (a1), from 29.5 to 78.5% by mass of (a2), from 1 to 5% by mass of (a3), from 0.5 to 30% by mass of (a4) and from 0.1 to 5% by mass of (a6).

11. The aqueous composition of claim 1, wherein: the polymerisation reaction further comprises: at least one monomer (a5) selected from the group consisting of polyalkylene glycol acrylate, polyalkylene glycol methacrylate, allyl polyalkylene glycol, methallyl polyalkylene glycol and 3-methyl-3-buten-1-ylpolyalkylene glycol; and at least one cross-linking monomer or at least one monomer comprising at least two olefinic unsaturations (a6); and the at least one copolymer comprises: from 19.9 to 68.9% by mass of (a1), from 29.5 to 78.5% by mass of (a2), from 1 to 5% by mass of (a3), from 0.5 to 30% by mass of (a5) and from 0.1 to 5% by mass of (a6).

12. The aqueous composition of claim 1, wherein: the polymerisation reaction further comprises: at least one compound (a4) of formula (I):
R.sup.1-(EO).sub.m—(PO).sub.n—R.sup.2  (I) wherein: m and n, identical or different, independently represent 0 or an integer or decimal less than 150, and m or n is not 0, EO represents a CH.sub.2CH.sub.2O group, each PO independently represents a group selected from the group consisting of CH(CH.sub.3)CH.sub.2O and CH.sub.2CH(CH.sub.3)O, R.sup.1 represents a group comprising at least one polymerisable olefinic unsaturation, and R.sup.2 represents a straight, branched or cyclical, saturated, unsaturated or aromatic hydrocarbon group comprising from 6 to 40 carbon atoms, at least one monomer (a5) selected from the group consisting of polyalkylene glycol acrylate, polyalkylene glycol methacrylate, allyl polyalkylene glycol, methallyl polyalkylene glycol and 3-methyl-3-buten-1-ylpolyalkylene glycol; and at least one cross-linking monomer or at least one monomer comprising at least two olefinic unsaturations (a6); and the at least one copolymer comprises: from 19.9 to 68.9% by mass of (a1), from 29 to 78% by mass of (a2), from 1 to 5% by mass of (a3), from 0.5 to 30% by mass of (a4), from 0.5 to 30% by mass of (a5) and from 0.1 to 5% by mass of (a6).

13. The aqueous composition of claim 1, wherein: the particles of the at least one mineral material have a size of less than 50 μm, or at least 60% by weight of the particles of the at least one mineral material have an equivalent spherical diameter of less than 50 μm.

14. The aqueous composition of claim 1, wherein: a single mineral material (b) or two or three mineral materials (b) are used or the at least one mineral material (b) is of synthetic or natural origin.

15. The aqueous composition of claim 1, wherein the at least one binding agent (c) is a natural binding agent or a synthetic binding agent.

16. The aqueous composition of claim 1, further comprising at least one admixture.

17. A method of paper or cardboard preparation, the method comprising contacting an article comprising paper or cardboard with the aqueous composition of claim 1.

18. The method of claim 17, wherein the method comprises coating the article comprising the paper or cardboard with the aqueous composition, and a water retention of the aqueous composition during the coating is improved compared to when no copolymer (a) is used.

19. The method of claim 17, wherein the method comprises coating the article comprising the paper or cardboard with the aqueous composition, and the coating comprises depositing the aqueous composition on a surface of the paper or cardboard to provide a coat weight, after drying, of from 5 to 50 g/m.sup.2.

20. An aqueous composition, comprising: from 0.02 to 2% by dry mass of at least one copolymer prepared by a polymerisation reaction comprising: at least one compound (a1-1) selected from the group consisting of acrylic acid, an acrylic acid salt and combinations thereof; at least one compound (a1-2) selected from the group consisting of methacrylic acid, a methacrylic acid salt and combinations thereof, in an (a1-1)/(a1-2) weight ratio of greater than 0.15; at least one compound (a2) selected from the group consisting of styrene, vinyl caprolactam, an ester of acrylic acid, an ester of methacrylic acid, an ester of itaconic acid, an ester of crotonic acid, an ester of maleic acid, an ester of maleic anhydride, and combinations thereof; at least one compound (a3) selected from the group consisting of 2-acrylamido-2-methylpropane sulphonic acid, 2-sulphoethyl methacrylate, sodium methallyl sulphonate, styrene sulphonate, salts thereof and combinations thereof; from 30 to 75% by dry mass of at least one mineral material in particle form; from 2 to 25% by dry mass of at least one binding agent; and 22.98 to 44.98% by mass of water.

Description

EXAMPLES

Example 1: Preparation and Characterization of Copolymers According to the Invention

(1) All of the synthesis reactions of copolymers (a) in the paper coating colour compositions according to the invention were carried out in a cylindrical glass reactor with a usable volume of 1 litre equipped with anchor-type mechanical agitation and oil bath heating. Stirring was maintained throughout the synthesis.

(2) Using a heat chamber at 110° C., the solids content of the synthesized products was measured. One gram of product was placed in the heat chamber for 1 hour. The difference in mass before and after drying enabled the solids content to be determined.

(3) Preparation and Characterization of the Copolymer (P1) According to the Invention

(4) In the glass reactor, an initial load comprised of 725 g of deionised water and 1.15 g of sodium bicarbonate are placed.

(5) In a first glass beaker, 136.43 g of monomer (a1-1) according to the proportions shown in table 1 and 204.99 g of ethyl acrylate (a2) are weighed.

(6) In a second glass beaker, 1.0 g of ammonium persulphate is weighed and then dissolved in 10 g of deionised water.

(7) In a third glass beaker, 0.1 g of sodium metabisulphite is weighed and then dissolved in 10 g of deionised water.

(8) In a disposable syringe, 7.5 g of 2-acrylamido-2-methylpropane sulphonic acid sodium salt (a3) at 50% by weight in water are weighed.

(9) Heat the reactor content to 76° C.±2° C.

(10) Inject the reagents from the 4 containers into the polymerization reactor over two hours at a temperature of 76° C.±2° C.

(11) 0.15 g of ammonium persulphate dissolved in 20 g of deionised water are then added, over 1 hour, keeping the temperature at 76° C.±2° C. To finish, bake for 1 hour before allowing the medium to cool and then filtering it. No scaling appears when preparing the copolymer.

(12) A copolymer (P1) is obtained at 28.4% by weight of solids content of which the composition is detailed in table 1.

(13) Preparation and Characterization of Copolymer (P2) According to the Invention

(14) In the glass reactor, an initial load comprised of 440 g of deionised water, 3.45 g of sodium dodecyl sulphate and 0.43 g of sodium bicarbonate are placed.

(15) In a first glass beaker, 116 g of monomer (a1-1) according to the proportions shown in table 1, 198 g of ethyl acrylate (a2), 1.12 g of sodium dodecyl sulphate, 0.14 g of sodium bicarbonate and 150 g of deionised water are weighed.

(16) In a second glass beaker, 1.0 g of ammonium persulphate is weighed and then dissolved in 10 g of deionised water.

(17) In a third glass beaker, 0.1 g of sodium metabisulphite is weighed and then dissolved in 10 g of deionised water.

(18) In a disposable syringe, 11.43 g of 2-acrylamido-2-methylpropane sulphonic acid sodium salt (a3) at 50% by weight in water are weighed.

(19) Heat the reactor content to 76° C.±2° C.

(20) Inject the reagents from the 4 containers into the polymerization reactor over two hours at a temperature of 76° C.±2° C.

(21) 0.15 g of ammonium persulphate dissolved in 20 g of deionised water are then added, over 5 minutes, keeping the temperature at 76° C.±2° C. To finish, bake for 1 hour before allowing the medium to cool and then filtering it. No scaling appears when preparing the copolymer.

(22) A copolymer (P2) is obtained at 32.7% by weight of solids content of which the composition is detailed in table 1.

(23) Preparation and Characterization of Copolymer (P3) According to the Invention

(24) In the glass reactor, an initial load comprised of 440 g of deionised water and 3.45 g of sodium dodecyl sulphate are placed.

(25) In a first glass beaker, 116 g of monomer (a1-1) according to the proportions shown in table 1, 198 g of ethyl acrylate (a2), 1.12 g of sodium dodecyl sulphate and 150 g of deionised water are weighed.

(26) In a second glass beaker, 1.0 g of ammonium persulphate is weighed and then dissolved in 10 g of deionised water.

(27) In a third glass beaker, 0.1 g of sodium metabisulphite is weighed and then dissolved in 10 g of deionised water.

(28) In a disposable syringe, 11.43 g of 2-acrylamido-2-methylpropane sulphonic acid sodium salt (a3) at 50% by weight in water are weighed.

(29) Heat the reactor content to 76° C.±2° C.

(30) Inject the reagents from the 4 containers into the polymerization reactor over two hours and 15 minutes at a temperature of 76° C.±2° C.

(31) To finish, bake for 1 hour before allowing the medium to cool and then filtering it. No scaling appears when preparing the copolymer.

(32) A copolymer (P3) is obtained at 32.5% by weight of solids content of which the composition is detailed in table 1.

(33) Preparation and Characterization of Copolymer (P4) According to the Invention

(34) In the glass reactor, an initial load comprised of 456.16 g of deionised water and 3.45 g of sodium dodecyl sulphate are placed.

(35) In a first glass beaker, 62.96 g of monomer (a1-1) according to the proportions shown in table 1, 96.71 g, of monomer (a1-2) according to the proportions shown in table 1, 153.59 g of ethyl acrylate (a2), 1.585 g of monomer (a4) of formula (I) in which R.sup.1 represents a methacrylate group, R.sup.2 represents a straight C.sub.22 alkyl group, m=25 and n=0 ((C.sub.22)—OE.sub.25 docosanol methacrylate), 1.12 g of sodium dodecyl sulphate and 160.37 g of deionised water are weighed.

(36) In a second glass beaker, 0.979 g of ammonium persulphate is weighed and then dissolved in 5 g of deionised water.

(37) In a third glass beaker, 0.098 g of sodium metabisulphite is weighed and then dissolved in 2 g of deionised water.

(38) In a disposable syringe, 11.4 g of 2-acrylamido-2-methylpropane sulphonic acid sodium salt (a3) at 50% by weight in water are weighed.

(39) Heat the reactor content to 76° C.±2° C.

(40) Inject the reagents from the 4 containers into the polymerization reactor over two hours at a temperature of 76° C.±2° C.

(41) 0.15 g of ammonium persulphate dissolved in 20 g of deionised water are the added, over 1 hour, keeping the temperature at 76° C.±2° C. To finish, bake for 1 hour before allowing the medium to cool and then filtering it. No scaling appears when preparing the copolymer.

(42) A copolymer (P4) is obtained at 32.3% by weight of solids content of which the composition is detailed in table 1.

(43) Preparation and Characterization of Copolymer (P5) According to the Invention

(44) In the glass reactor, an initial load comprised of 456.16 g of deionised water, 1.15 g of sodium bicarbonate and 3.45 g of sodium dodecyl sulphate are placed.

(45) In a first glass beaker, 134.92 g of monomer (a1-1) according to the proportions shown in table 1, 1.1095 g, of monomer (a1-2) according to the proportions shown in table 1, 177.19 g of ethyl acrylate (a2), 1.585 g of monomer (a4) of formula (I) in which R.sup.1 represents a methacrylate group, R.sup.2 represents a straight C.sub.22 alkyl group, m=25 and n=0 ((C.sub.22)—OE.sub.25 docosanol methacrylate), 1.12 g of sodium dodecyl sulphate and 160.37 g of deionised water are weighed.

(46) In a second glass beaker, 0.979 g of ammonium persulphate is weighed and then dissolved in 5 g of deionised water.

(47) In a third glass beaker, 0.098 g of sodium metabisulphite is weighed and then dissolved in 2 g of deionised water.

(48) In a disposable syringe, 11.4 g of 2-acrylamido-2-methylpropane sulphonic acid sodium salt (a3) at 50% by weight in water are weighed.

(49) Heat the reactor content to 76° C.±2° C.

(50) Inject the reagents from the 4 containers into the polymerization reactor over two hours at a temperature of 76° C.±2° C.

(51) 0.15 g of ammonium persulphate dissolved in 20 g of deionised water are then added, over 1 hour, keeping the temperature at 76° C.±2° C. To finish, bake for 1 hour before allowing the medium to cool and then filtering it. No scaling appears when preparing the copolymer.

(52) A copolymer (P5) is obtained at 31.7% by weight of solids content of which the composition is detailed in table 1.

(53) Preparation and Characterization of Copolymer (P6) According to the Invention

(54) In the glass reactor, an initial load comprised of 458.75 g of deionised water, 6.46 g of sodium dodecyl sulphate and 5.41 g of tridecyl alcohol tri-ethoxylate (Rhodasurf ID030, Solvay) are placed.

(55) In a first glass beaker, 103.66 g of monomer (a1-1) according to the proportions shown in table 1, 20.11 g of monomer (a1-2) according to the proportions shown in table 1, 158.06 g of ethyl acrylate (a2), 21.05 g of monomer (a4) of formula (I) in which R.sup.1 represents a methacrylate group, R.sup.2 represents an alkyl group derived from a C.sub.16 Guerbet alcohol, m=25 and n=0 (C.sub.16-OE.sub.25 Guerbet alcohol methacrylate), 2.26 g of sodium dodecyl sulphate, 0.065 g of dodecyl mercaptan and 136.72 g of deionised water are weighed.

(56) In a second glass beaker, 0.917 g of ammonium persulphate is weighed and then dissolved in 4.85 g of deionised water.

(57) In a third glass beaker, 0.092 g of sodium metabisulphite is weighed and then dissolved in 19.39 g of deionised water.

(58) In a disposable syringe, 5.28 g of 2-acrylamido-2-methylpropane sulphonic acid sodium salt (a3) at 50% by weight in water are weighed.

(59) Heat the reactor content to 76° C.±2° C.

(60) Inject the reagents from the 4 containers into the polymerization reactor over two hours at a temperature of 76° C.±2° C.

(61) 0.101 g of ammonium persulphate dissolved in 51.5 g of deionised water are then added, over 5 minutes, keeping the temperature at 76° C.±2° C. To finish, bake for 1 hour before allowing the medium to cool and then filtering it. No scaling appears when preparing the copolymer.

(62) A copolymer (P6) is obtained at 30.1% by weight of solids content of which the composition is detailed in table 1.

(63) Preparation and Characterization of Copolymer (P7) According to the Invention

(64) In the glass reactor, an initial load comprised of 458.75 g of deionised water, 6.46 g of sodium dodecyl sulphate and 5.41 g of tridecyl alcohol tri-ethoxylate (Rhodasurf ID030, Solvay) are placed.

(65) In a first glass beaker, 82.93 g of monomer (a1-1) according to the proportions shown in table 1, 40.84 g of monomer (a1-2) according to the proportions shown in table 1, 158.06 g of ethyl acrylate (a2), 21.05 g of monomer (a4) of formula (I) in which R.sup.1 represents a methacrylate group, R.sup.2 represents an alkyl group derived from a C.sub.16 Guerbet alcohol, m=25 and n=0 (C.sub.16-OE.sub.25 Guerbet alcohol methacrylate), 2.26 g of sodium dodecyl sulphate, 0.065 g of dodecyl mercaptan and 136.72 g of deionised water are weighed

(66) In a second glass beaker, 0.917 g of ammonium persulphate is weighed and then dissolved in 4.85 g of deionised water.

(67) In a third glass beaker, 0.092 g of sodium metabisulphite is weighed and then dissolved in 19.39 g of deionised water.

(68) In a disposable syringe, 5.28 g of 2-acrylamido-2-methylpropane sulphonic acid sodium salt (a3) at 50% by weight in water are weighed.

(69) Heat the reactor content to 76° C.±2° C.

(70) Inject the reagents from the 4 containers into the polymerization reactor over two hours at a temperature of 76° C.±2° C.

(71) 0.101 g of ammonium persulphate dissolved in 51.5 g of deionised water are then added, over 5 minutes, keeping the temperature at 76° C.±2° C. To finish, bake for 1 hour before allowing the medium to cool and then filtering it. No scaling appears when preparing the copolymer.

(72) A copolymer (P7) is obtained at 30.1% by weight of solids content of which the composition is detailed in table 1.

(73) Preparation and Characterization of Copolymer (P8) According to the Invention

(74) In the glass reactor, an initial load comprised of 475 g of deionised water, 6.46 g of sodium dodecyl sulphate and 5.41 g of tridecyl alcohol tri-ethoxylate (Rhodasurf ID030, Solvay) are placed.

(75) In a first glass beaker, 28.84 g of monomer (a1-1) according to the proportions shown in table 1, 102.97 g of monomer (a1-2) according to the proportions shown in table 1, 143.93 g of ethyl acrylate (a2), 12.69 g of monomer (a4) of formula (I) in which R.sup.1 represents a methacrylate group, R.sup.2 represents an alkyl group derived from a C.sub.16 Guebet alcohol, m=25 and n=0 (C.sub.16-OE.sub.25 Guerbet alcohol methacrylate), 2.26 g of sodium dodecyl sulphate, and 139.76 g of deionised water are weighed.

(76) In a second glass beaker, 0.92 g of ammonium persulphate is weighed and then dissolved in 4.85 g of deionised water.

(77) In a third glass beaker, 0.092 g of sodium metabisulphite is weighed and then dissolved in 4.85 g of deionised water.

(78) In a disposable syringe, 5.28 g of 2-acrylamido-2-methylpropane sulphonic acid sodium salt (a3) at 50% by weight in water are weighed.

(79) Heat the reactor content to 76° C.±2° C.

(80) Inject the reagents from the 4 containers into the polymerization reactor over two hours at a temperature of 76° C.±2° C.

(81) 0.101 g of ammonium persulphate dissolved in 51.5 g of deionised water are then added, over 5 minutes, keeping the temperature at 76° C.±2° C.

(82) To finish, bake for 1 hour before allowing the medium to cool and then filtering it. No scaling appears when preparing the copolymer.

(83) A copolymer (P8) is obtained at 30.4% by weight of solids content of which the composition is detailed in table 1.

(84) Preparation and Characterization of Copolymer (P9) According to the Invention

(85) In the glass reactor, an initial load comprised of 475 g of deionised water, 6.46 g of sodium dodecyl sulphate and 5.41 g of tridecyl alcohol tri-ethoxylate (Rhodasurf ID030, Solvay) are placed.

(86) In a first glass beaker, 28.84 g of monomer (a1-1) according to the proportions shown in table 1, 102.97 g, of monomer (a1-2) according to the proportions shown in table 1, 143.93 g of ethyl acrylate (a2), 12.69 g of monomer (a4) of formula (I) in which R.sup.1 represents a methacrylate group, R.sup.2 represents a straight C.sub.18 alkyl group, m=25 and n=0, 2.26 g of sodium dodecyl sulphate and 139.76 g of deionised water are weighed.

(87) In a second glass beaker, 0.92 g of ammonium persulphate is weighed and then dissolved in 4.85 g of deionised water.

(88) In a third glass beaker, 0.092 g of sodium metabisulphite is weighed and then dissolved in 4.85 g of deionised water.

(89) TABLE-US-00001 Monomer amount-% by weight) Copolymer (a1) (a2) (a3) (a4) P1 AA (39.52) EA AMPS — (59.39) (1.09) P2 AA (36.28) EA AMPS — (61.93) (1.79) P3 AA (36.28) EA AMPS — (61.93) (1.79)

(90) In a disposable syringe, 5.28 g of 2-acrylamido-2-methylpropane sulphonic acid sodium salt (a3) at 50% by weight in water are weighed.

(91) Heat the reactor content to 76° C.±2° C.

(92) Inject the reagents from the 4 containers into the polymerization reactor over two hours at a temperature of 76° C.±2° C.

(93) 0.101 g of ammonium persulphate dissolved in 51.5 g of deionised water are then added, over 5 minutes, keeping the temperature at 76° C.±2° C.

(94) To finish, bake for 1 hour before allowing the medium to cool and then filtering it. No scaling appears when preparing the copolymer.

(95) A copolymer (P9) is obtained at 29.9% by weight of solids content, of which the composition is detailed in table 1.

(96) TABLE-US-00002 TABLE 1 P4 AA (19.64) EA AMPS (C.sub.22)—OE.sub.25 docosanol MAA (30.17) (47.92) (1.78) methacrylate (0.49) P5 AA (42.10) EA AMPS (C.sub.22)—OE.sub.25 docosanol MAA (0.35) (55.28) (1.78) methacrylate (0.49) P6 AA (33.93) EA AMPS C.sub.16—OE.sub.25 Guerbet alcohol MAA (6.58) (51.73) (0.86) methacrylate (6.90) P7 AA (27.14) EA AMPS C.sub.16—OE.sub.25 Guerbet alcohol MAA (13.37) (51.73) (0.86) methacrylate (6.90) P8 AA (9.91) EA AMPS C.sub.16—OE.sub.25 Guerbet alcohol MAA (35.38) (49.45) (0.91) methacrylate (4.35) P9 AA (9.91) EA AMPS C.sub.18—OE.sub.25 straight alcohol MAA (35.38) (49.45) (0.91) methacrylate (4.35) AA: acrylic acid MAA: methacrylic acid EA: ethyl acrylate

Example 2: Preparation and Characterization of Comparative Copolymers

(97) Preparation and Characterization of the Comparative Copolymer (PC1)

(98) In the glass reactor, an initial load comprised of 475 g of deionised water, 6.46 g of sodium dodecyl sulphate and 5.41 g of tridecyl alcohol tri-ethoxylate (Rhodasurf ID030, Solvay) are placed.

(99) In a first glass beaker, 28.84 g of monomer (a1-1) according to the proportions shown in table 2, 102.97 g of monomer (a1-2) according to the proportions shown in table 2, 143.93 g of ethyl acrylate (a2), 12.69 g of monomer (a4) of formula (I) in which R.sup.1 represents a methacrylate group, R.sup.2 represents an alkyl group derived from a C.sub.16 Guerbet alcohol, m=25 and n=0, 2.26 g of sodium dodecyl sulphate, and 139.76 g of deionised water are weighed.

(100) In a second glass beaker, 0.92 g of ammonium persulphate is weighed and then dissolved in 4.85 g of deionised water.

(101) In a third glass beaker, 0.092 g of sodium metabisulphite is weighed and then dissolved in 4.85 g of deionised water.

(102) Heat the reactor content to 76° C.±2° C.

(103) Inject the reagents from the 3 containers into the polymerization reactor. The reaction medium is then kept at 76° C.±2° C. for 2 hours.

(104) 0.101 g of ammonium persulphate dissolved in 51.5 g of deionised water are then added, over 5 minutes, keeping the temperature at 76° C.±2° C.

(105) To finish, bake for 1 hour before allowing the medium to cool and then filtering it. Scaling appeared in the reactor, in an amount of 100 g. It proved impossible to obtain comparative copolymer (PC1).

(106) Preparation and Characterization of the Comparative Copolymer (PC2)

(107) In the glass reactor, an initial load comprised of 475 g of deionised water, 6.46 g of sodium dodecyl sulphate and 5.41 g of tridecyl alcohol tri-ethoxylate (Rhodasurf ID030, Solvay) are placed.

(108) In a first glass beaker, 28.84 g of monomer (a1-1) according to the proportions shown in table 2, 102.97 g of monomer (a1-2) according to the proportions shown in table 2, 143.93 g of ethyl acrylate (a2), 12.69 g of monomer (a4) of formula (I) in which R.sup.1 represents a methacrylate group, R.sup.2 represents a combination of straight C.sub.16 and C.sub.18 alkyl groups, m=25 and n=0, 2.26 g of sodium dodecyl sulphate, and 139.76 g of deionised water are weighed.

(109) In a second glass beaker, 0.92 g of ammonium persulphate is weighed and then dissolved in 4.85 g of deionised water.

(110) In a third glass beaker, 0.092 g of sodium metabisulphite is weighed and then dissolved in 4.85 g of deionised water.

(111) Heat the reactor content to 76° C.±2° C.

(112) Inject the reagents from the 3 containers into the polymerization reactor. The reaction medium is then kept at 76° C.±2° C. for 2 hours.

(113) 0.101 g of ammonium persulphate dissolved in 51.5 g of deionised water are then added, over 5 minutes, keeping the temperature at 76° C.±2° C.

(114) To finish, bake for 1 hour before allowing the medium to cool and then filtering it.

(115) Scaling appeared in the reactor, in an amount of 100 g. It proved impossible to obtain comparative copolymer (PC2).

(116) Preparation and Characterization of the Comparative Copolymer (PC3)

(117) In the glass reactor, an initial load comprised of 451.28 g of deionised water and 3.45 g of sodium dodecyl sulphate are placed.

(118) 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 water are weighed.

(119) In a second glass beaker, 0.979 g of ammonium persulphate is weighed and then dissolved in 5 g of deionised water.

(120) In a third glass beaker, 0.098 g of sodium metabisulphite is weighed and then dissolved in 2 g of deionised water.

(121) In a disposable syringe, 11.4 g of 2-acrylamido-2-methylpropane sulphonic acid sodium salt (a3) at 50% by weight in water are weighed.

(122) Heat the reactor content to 76° C.±2° C.

(123) Inject the reagents from the 4 containers into the polymerization reactor over two hours at a temperature of 76° C.±2° C.

(124) 0.114 g of ammonium persulphate dissolved in 20 g of deionised water are then added, over 1 hour, keeping the temperature at 76° C.±2° C. To finish, bake for 1 hour before allowing the medium to cool and then filtering it. No scaling appears when preparing the copolymer.

(125) A comparative copolymer (PC3) was obtained at 31.0% by weight of solids content, of which the composition is detailed in table 2. AA: acrylic acid MAA: methacrylic acid EA: ethyl acrylate

(126) TABLE-US-00003 TABLE 2 Comparative Monomer (quantity-% by weight) Copolymer (a1) (a2) (a3) (a4) PC1  AA (10.00) EA — C.sub.16—OE.sub.25 Guerbet MAA (35.70) (49.90) alcohol methacrylate (4.40) PC2  AA (10.00) EA — C.sub.16—OE.sub.25 Guerbet MAA (35.70) (49.90) alcohol methacrylate (4.40) PC3 MAA (36.22) EA AMPS — (62.00) (1.78)

Example 3: Preparation and Characterization of Paper Coating Colours According to the Invention and Comparatives

(127) The polymers according to the invention and polymers from the prior art were used in combination with the following products in the aqueous compositions for paper coating colours: CaCO.sub.3 pigment 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 Petrochemical), at 25% by weight in water.

(128) The proportions (in g, dry for dry) of the constituents of the compositions for paper coating colours are shown in table 3.

(129) The solids content of the paper coating colours are measured dry using a CEM microwave scales. A piece of sandpaper is coated with paper coating colour at a mass determined between 1 and 4 g. Then it is dried in the microwave scales.

(130) The scales stop drying when the weight no longer changes for 10 sec. The weight difference is expressed in %, which determines the solids content.

(131) The pH is measured at 25° C. using a WTW pH-meter with a conventional electrode coupled to a temperature probe.

(132) The Brookfield viscosity of the compositions prepared is measured at 100 rpm at 25° C. using an analogue viscosity meter. The spindle is chosen according to the viscosity of the composition studied so as to be within the optimal use range of the rheometer. ACAV capillary viscosity at 10.sup.6 s.sup.−1 is measured using an ACAV A2 capillary meter by ACA.

(133) Water retention is determined 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 colour is 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 water-soluble substances in the coating to pass through the perforated plastic sheet and migrate 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 colour that migrated into the test paper during the measurement. The relative value of the increase in water retention is 1,250×(P1−P0)/P0.

(134) The results obtained are shown in table 3.

(135) TABLE-US-00004 TABLE 3 Composition according to the invention Comparative C1 C2 C3 C4 C5 CC1 CC2 CC3 (a) polymer P1 0.12 (a) polymer P2 0.4 (a) polymer P3 0.4 (a) polymer P6 0.2 (a) polymer P7 0.2 polymer PC3 0.4 (b) Hydrocarb 60 100 100 (b) Hydrocarb 90 100 100 20 20 100 20 (b) Hydrocarb 95 80 80 80 (c) DL 1066 latex 7 8 8 7 7 7 8 7 (c) Stabilys A30 1 1 1 Mowiol PV-OH 1 0.5 0.5 1 0.5 4-98 Solids content (%) 71 63 63 67.1 67.1 71 63 67.1 pH after addition 9.2 8.5 8.5 8.8 8.8 9.2 8.5 8.8 of NaOH 12.5% by weight in water Brookfield 710 1,270 1,140 2,515 2,230 285 1,110 380 viscosity @ 100 rpm (mPa .Math. s) Acav HSV 126 79 76 82 53 viscosity @ 10.sup.6s.sup.-1 (mPa .Math. s) AAGWR water 113 78 78 110 107 350 88 211 retention (2μm- 1.5b-90s) (g/m.sup.2)

(136) With 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 retention to the paper coating colour.

(137) With respect to the comparative composition (CC2) which comprises a thickening agent prepared from methacrylic acid and without acrylic acid, the presence of polymers (P2) and (P3) also makes it possible to improve these properties.

(138) With respect to the comparative composition (CC3) which does not comprise a thickening agent, the presence of polymers (P6) and (P7) also makes it possible to provide good properties.