Novel polymer and method for preparing the same

Abstract

The present invention relates to a novel anionic water-soluble polymer, a method for preparing the same, and its use particularly in the paper field.

Description

Technical Field

[0001] The present invention relates to a novel anionic water-soluble polymer, a method for preparing the same, and its use, particularly in the field of paper.

Background Art

[0002] In the paper industry, efforts are constantly being made to improve the manufacturing methods of paper, cardboard, etc., particularly in terms of cost reduction, yield, productivity, and the quality of the final product.

[0003] This is particularly true in the packaging industry, which is seeking paper, cardboard, etc. with better dry strength performance in order to address current environmental issues and replace plastic packaging. The pursuit of this improvement should not be at the expense of productivity.

[0004] The dry strength of paper is, by definition, the strength of a sheet, cardboard, etc. in a dry state. Traditionally, the value of the mechanical strength provides a measure of the dry strength. In particular, mention can be made of burst strength, tensile strength, compressive strength, peel strength, etc.

[0005] It is well known to use water-soluble cationic polymers to improve the strength properties of paper. By their nature, these polymers can directly adhere to anionic cellulose and impart a cationic charge, so they can cooperate with anionic polymers to cause the latter to adhere to cellulose fibers and improve the dry strength of the sheet.

[0006] JP2012 251252 discloses a papermaking method including an amphoteric polymer.

[0007] The most commonly used cationic polymers are cationic starches, polyamide epichlorohydrin (PAE), polyamide amine epichlorohydrin (PAAE), optionally glyoxalated cationic polyacrylamide, polyvinylamine, polyethyleneimine (PEI), polyamine epichlorohydrin resin (PA), or compounds of the type of polymers obtained by Hofmann degradation.

[0008] This combination of a cationic polymer and an anionic polymer to improve dry strength is well known. In particular, in document FR2880901 B1, it has already been proposed to combine a cationic polymer and an anionic polymer, and the purpose of this combination is to provide a system effective for the dry strength of paper sheets.

[0009] The problem with such a bond between the two polymers in solution is that the drainage of the paper is lost. When the drainage decreases, the speed of the papermaking machine decreases, causing a significant decrease in productivity.

[0010] This problem is mainly due to an anionic polymer synthesized by a liquid method and having a low molecular weight. In the liquid method, the viscosity increases as the molecular weight increases. Beyond a certain molecular weight, it becomes impossible to obtain a liquid.

[0011] To overcome this problem, manufacturers had to rely on other polymerization techniques such as gel polymerization to obtain higher molecular weights. The polymers obtained from these polymerization techniques are in solid form.

[0012] There are numerous disadvantages associated with the use of polymers in solid form. For example, - Manufacturers are obliged to have a powder dilution system on site. - Increase in the size of the equipment and thereby the installation area. - Increase in energy consumption and maintenance. - Management of powder inventory. - Management of pre - dissolution of powder. - More frequent and more complex maintenance.

[0013] The main problem is the dissolution of high molecular weight polymer powder. In fact, the dissolution of such polymers is not easy and leads to the formation of aggregates on the paper sheet, making the paper sheet fragile and, worse still, causing machine fouling and potentially resulting in a complete shutdown and maintenance of the entire production unit. To avoid the risk of insufficient dissolution, technical know-how is required. Furthermore, in powder form, this type of high molecular weight polymer causes excessive agglomeration, has a harmful effect on sheet formation, and negatively impacts the mechanical properties of the paper.

Prior Art Documents

Patent Documents

[0014]

Patent Document 1

Patent Document 2

Patent Document 3

Non-Patent Documents

[0015]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0016] Manufacturers have long been seeking a solution that enables them to obtain paper sheets with good dry strength performance while maintaining satisfactory drainage and simplifying installation by using polymers in liquid form.

Means for Solving the Problems

[0017] The Applicant has surprisingly discovered that the synthesis of the polymer by the method of the present invention can meet the needs of manufacturers without disadvantaging them.

[0018] The use of the polymer derived from the present invention is part of the general principle of improving the performance of the product, more specifically the dry strength and drainage. The good performance of the polymer according to the present invention can reduce the amount of the product required for the application, and is accompanied by a reduction in the emission of greenhouse gases such as CO 2 etc.

[0019] The present invention relates to - at least one anionic monomer A, - at least one nonionic monomer B, - at least one structuring system and is an anionic water-soluble polymer comprising wherein at least one structuring system is (i) at least one compound I selected from allylsulfonic acid, methallylsulfonic acid, allyldisulfonic acid, methallyldisulfonic acid, salts thereof, and mixtures thereof, which is different from at least one monomer A, (ii) at least one formula II that is different from at least one monomer B:

[0020]

Chemical formula

[0021] (wherein R 1 and R 2 are each independently a hydrogen atom, a methyl group, an ethyl group, an isopropyl group, or a CH 2 -OH group, R 1 and R 2 are not both hydrogen atoms (when R 2 =H, R 1 ≠H; when R 1 =H, R 2 ≠H)) Compound II and comprising an anionic water-soluble polymer.

[0022] This anionic water-soluble polymer is obtained by the following steps: a) A step of forming a solution (S1) containing a first fraction (F1) comprising at least one monomer selected from monomer A and monomer B and at least one compound selected from compound I and compound II; b) A polymerization step 1 (PO1) of fraction F1 to form a solution of a first gradient polymer (PG1); c) A step of adding a second fraction (F2) comprising at least one monomer selected from monomer A and monomer B and at least one compound selected from compound I and compound II to the solution containing PG1; d) A polymerization step 2 (PO2) of fraction F2 in PG1 to form a solution of a second gradient polymer (PG2); e) A step of adding a third fraction (F3) comprising at least one monomer selected from monomer A and monomer B and at least one compound selected from compound I and compound II to the solution containing PG2; f) A polymerization step 3 (PO3) of fraction F3 in PG2 to form a solution containing the anionic water-soluble polymer and is obtained by At least one of fraction F1, F2, or F3 contains at least one monomer A, at least one of fraction F1, F2, or F3 contains at least one monomer B, at least one of fraction F1, F2, or F3 contains at least one compound I, and at least one of fraction F1, F2, or F3 contains at least one compound II.

[0023] This anionic water-soluble polymer does not contain a cationic monomer and an amphoteric ion monomer.

[0024] In the present invention, the first gradient polymer and the second gradient polymer are prepolymers.

[0025] The present invention also relates to a method for preparing this anionic water-soluble polymer. It is a sequential polymerization method.

[0026] The present invention also relates to a method for manufacturing paper and cardboard using this anionic water-soluble polymer.

[0027] The present invention also relates to the use of this anionic water-soluble polymer in the recovery of hydrocarbons (oil and / or gas); in well drilling or cementing; in hydrocarbon wells (oil and / or gas), for example, in hydraulic fracturing, conditioning, and stimulation of diversion; in the treatment of water in open, closed, or semi-closed circulation; in the treatment of fermentation must; in the treatment of sludge; in construction; in the treatment of wood; in the treatment of hydraulic compositions (concrete, cement, mortar, and aggregates); in the mining industry; in the formulation of cosmetic products; in the battery industry; in the formulation of surfactants; in the manufacture of textiles; in geothermal technology; in the manufacture of diapers; or in agriculture.

[0028] The present invention also relates to the use of this anionic water-soluble polymer as a flocculant, coagulant, binder, solidifying agent, viscosity reducer, thickener, absorbent, friction reducer, drainage agent, filler retainer, dehydrating agent, condition regulator, stabilizer, solidifying agent, film-forming agent, sizing agent, superplasticizing agent, clay inhibitor, or dispersant.

Embodiments for Carrying Out the Invention

[0029] "Polymer" refers to a copolymer prepared from at least two different monomers including at least one anionic monomer A and at least one nonionic monomer B, and from a structuring system including at least one compound I and at least one compound II. Optionally, it can include at least one hydrophobic monomer and / or crosslinking agent and / or migrating agent.

[0030] A water-soluble polymer is understood to mean a polymer that forms an aqueous solution without insoluble particles when dissolved at a concentration of 10 g·L -1 under stirring in deionized water at 25°C.

[0031] Throughout the description, the viscosity is measured in an aqueous solution at 25°C using a Brookfield viscometer equipped with a Brookfield LV3 module.

[0032] In this specification, it is considered that those skilled in the art can determine the appropriate module and speed of the Brookfield viscometer according to the viscosity range to be measured. This type of measurement is actually part of the general knowledge of those skilled in the art.

[0033] According to the present invention, "X and / or Y" is understood to mean "X", or "Y", or "X and Y".

[0034] Also, whether it is a preferred embodiment or an embodiment shown as an example, all possible combinations among different disclosed embodiments are also part of the present invention. Further, when a range of values is indicated, the limits are part of these ranges. The disclosure includes all combinations between the limits of these ranges of values. For example, a range of values of "1 to 20, preferably 5 to 15" means the disclosure of ranges of "1 to 5", "1 to 15", "5 to 20", "15 to 20", and the values of 1, 5, 15, and 20.

[0035] Anionic water-soluble polymer The anionic water-soluble polymer of the present invention is - at least one anionic monomer A, and - at least one nonionic monomer B, and - at least one structuring system and includes wherein the at least one structuring system is (i) At least one compound I selected from allylsulfonic acid, methallylsulfonic acid, allyldisulfonic acid, methallyldisulfonic acid, salts thereof, and mixtures thereof, which is different from at least one monomer A, and (ii) At least one compound II of formula II, which is different from at least one monomer B

[0036] [Chemical formula]

[0037] (wherein R 1 and R 2 are, independently of each other, a hydrogen atom, a methyl group, an ethyl group, an isopropyl group, or a CH 2 -OH group, and R 1 and R 2 are not both hydrogen atoms (when R 2 =H, R 1 ≠H; when R 1 =H, R 2 ≠H)) is included. This polymer does not contain cationic monomers and zwitterionic monomers.

[0038] Monomer composition The anionic water-soluble polymer of the present invention is a synthetic polymer. It can contain one or more anionic monomers (also referred to as "monomer A").

[0039] Advantageously, the anionic monomer A or other anionic monomer A can be selected from a large group. These monomers can have a vinyl functional group, particularly an acrylic functional group, maleic acid functional group, fumaric acid functional group, malonic acid functional group, itaconic acid functional group, or allyl functional group. They can also contain a carboxylate group, phosphonate group, phosphate group, sulfonate group, or other anionic charge group. Preferred monomers belonging to this class are, for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, acrylamidoundecanoic acid, 3-acrylamido-3-methylbutanoic acid, maleic anhydride, 2-acrylamido-2-methylpropanesulfonic acid (ATBS), vinylsulfonic acid, vinylphosphonic acid, 2-sulfoethyl methacrylate, sulfopropyl methacrylate, sulfopropyl acrylate, allylphosphonic acid, styrenesulfonic acid, 2-acrylamido-2-methylpropanedisulfonic acid, their salts, and mixtures thereof. Preferably, these monomers are acrylic acid or itaconic acid, and even more preferably, acrylic acid.

[0040] Thus, in certain embodiments of the present invention, the anionic monomer A can be chlorinated.

[0041] Chlorination is understood to mean that at least one proton of the acid functional group of the anionic monomer A of the type -R(O)-OH (R = P, S, or C) is replaced by a metal cation to form a salt of the type -R(O)-OX (X is a metal cation). In other words, the non-chlorinated form corresponds to the acid form of the monomer, for example, R-C(=O)-OH in the case of a carboxylic acid functional group, while the chlorinated form of the monomer corresponds to the R-C(=O)-O-X+ form, where X+ corresponds to an alkali cation. The chlorination of the acid functional groups of the water-soluble polymer can be partial or complete.

[0042] The chloride form preferably corresponds to a salt of an alkali metal (Li, Na, K, etc.), an alkaline earth metal (Ca, Mg, etc.) or ammonium (e.g., ammonium ion or quaternary ammonium). A preferred salt is the sodium salt.

[0043] Chlorination can be carried out before or after polymerization.

[0044] The anionic water-soluble polymer preferably contains 1 to 99 mol%, preferably 2 to 70 mol%, more preferably 3 to 50 mol%, still more preferably 5 to 35 mol% of anionic monomer A.

[0045] In a particular embodiment of the invention, when the anionic monomer A is 2-acrylamido-2-methylpropanesulfonic acid, it is in its hydrated form. The hydrated form of ATBS is a specific form of ATBS that can be obtained by controlled crystallization of the ATBS monomer. This hydrated form of ATBS is described in document US10,759,746.

[0046] The anionic water-soluble polymer can contain one or more nonionic monomers (referred to as "monomer B").

[0047] Preferably, the nonionic monomer B can be selected from the group consisting of, in particular, water-soluble vinyl monomers. Preferred monomers belonging to this class are, for example, acrylamide, methacrylamide, N-vinylformamide (NVF), N-vinylacetamide, N-vinylpyrrolidone (NVP), N-vinylimidazole, N-vinylsuccinimide, acryloylmorpholine (ACMO), acryloyl chloride, glycidyl methacrylate, glyceryl methacrylate, diacetone acrylamide, hydroxyalkyl (meth)acrylate (C 1 ~C 3 alkyl), thioalkyl (meth)acrylate (C 1 ~C 3 alkyl), and mixtures thereof. Preferably, this is acrylamide.

[0048] The anionic water-soluble polymer preferably contains 1 to 99 mol%, preferably 30 to 98 mol%, more preferably 50 to 97 mol%, even more preferably 65 to 95 mol% of the nonionic monomer B.

[0049] The anionic water-soluble polymer may optionally contain one or more hydrophobic monomers (referred to as "monomer C").

[0050] Preferably, the hydrophobic monomer C is a propoxylated, ethoxylated, or ethoxylated and propoxylated C 4 ~C 30 alkyl, arylalkyl (C 4 ~C 30 alkyl, C 4 ~C 30 aryl) chain of (meth)acrylic acid ester; C 1 ~C 3 alkyl, propoxylated arylalkyl (C 4 ~C 30 alkyl, C 4 ~C 30 aryl), ethoxylated, ethoxylated and propoxylated, or dialkyl (C 4 ~C 30 alkyl) chain of (meth)acrylamide derivative; propoxylated, ethoxylated, or ethoxylated and propoxylated, alkylaryl sulfonate (C 4 ~C 30 alkyl, C 4 ~C 30 aryl), or C 4 ~C 30 alkyl, arylalkyl (C 4 ~C 30 alkyl, C 4 ~C 30 aryl) chain of (meth)acrylamide mono-substituted or di-substituted amide; ethoxylated, ethoxylated and propoxylated, C 4 ~C 30alkyl, propoxylated arylalkyl (C 4 ~C 30 alkyl, C 4 ~C 30 aryl), or C 4 ~C 30 having a dialkyl chain of (meth)acrylamide derivatives; alkylarylsulfonate (C 4 ~C 30 alkyl, C 4 ~C 30 aryl), and mixtures thereof can be selected from the group consisting of.

[0051] The anionic water-soluble polymer preferably contains at least 1 mol% of at least one hydrophobic monomer C. It may not contain hydrophobic monomer C. When the anionic water-soluble polymer of the present invention contains one or more hydrophobic monomers C, they are present in an amount such that the polymer remains water-soluble.

[0052] The amounts of the different monomers are adjusted by those skilled in the art so as not to exceed 100 mol% during the preparation of the water-soluble polymer. Preferably, monomers A and B represent 100 mol% of the monomers of the anionic water-soluble polymer.

[0053] Structuring system The structuring system of the anionic water-soluble polymer is (i) at least one compound I, and (ii) at least one compound II including.

[0054] Compound I used in the context of the present invention is selected from allylsulfonic acid, methallylsulfonic acid, allyldisulfonic acid, methallyldisulfonic acid, salts thereof, and mixtures thereof. Preferably, it is methallylsulfonic acid, for example, sodium methallylsulfonate.

[0055] The chloride form preferably corresponds to a salt of an alkali metal (Li, Na, K, etc.), an alkaline earth metal (Ca, Mg, etc.) or ammonium (e.g., ammonium ion or quaternary ammonium). A preferred salt is the sodium salt.

[0056] The anionic water-soluble polymer preferably contains 500 to 50,000 ppm, preferably 1,000 to 20,000 ppm, more preferably 2,000 to 10,000 ppm of Compound I, based on the total mass of monomers A and B (+ optionally monomer C) of the anionic water-soluble polymer.

[0057] Compound II used in the context of the present invention has the following general formula.

[0058]

Chemical formula

[0059] (In the formula, R 1 and R 2 are each independently a hydrogen atom, a methyl group, an ethyl group, an isopropyl group, or a CH 2 -OH group, and R 1 and R 2 are not both hydrogen atoms (when R 2 = H, R 1 ≠ H; when R 1 = H, R 2 ≠ H)).

[0060] Compound II used in the context of the present invention is preferably selected from N,N-dimethylacrylamide, N,N-diethylacrylamide, N,N-isopropylacrylamide, N-methylolacrylamide, and mixtures thereof. Preferably, it is N,N-dimethylacrylamide.

[0061] The anionic water-soluble polymer of the present invention preferably contains 500 to 50,000 ppm, preferably 1,000 to 20,000 ppm, more preferably 2,000 to 10,000 ppm of Compound II based on the total mass of monomers A and B (+ optionally monomer C) of the anionic water-soluble polymer.

[0062] In the anionic water-soluble polymer, the mass ratio of Compound I to Compound II is preferably from 0.01 to 100, and more preferably from 0.1 to 10.

[0063] In a preferred embodiment of the present invention, the amount of Compound I is more than that of Compound II. Therefore, the mass ratio of Compound I to Compound II is preferably more than 1 and 100 or less, and more preferably more than 1 and 10 or less.

[0064] Optional The anionic water-soluble polymer can further contain at least one crosslinking agent. This crosslinking agent can be selected from, for example, polyethylene unsaturated monomers having vinyl functional groups, particularly allyl functional groups, acrylic functional groups, etc. (having at least two unsaturated functional groups), or monomers having at least two epoxy functional groups. For example, methylene bisacrylamide (MBA), triallylamine, tetraallylammonium chloride, 1,2-dihydroxyethylene bis-(N-acrylamide), and mixtures thereof can be mentioned. Preferably, it is methylene bisacrylamide (MBA).

[0065] The amount of the crosslinking agent in the anionic water-soluble polymer is preferably 5 to 5,000 ppm, and more preferably 50 to 3,000 ppm based on the total mass of monomers A and B (+ optionally monomer C) of the anionic water-soluble polymer.

[0066] In a specific embodiment of the present invention, the anionic water-soluble polymer does not contain a crosslinking agent.

[0067] The anionic water-soluble polymer of the present invention can further contain at least one chain transfer agent selected from, for example, methanol, isopropyl alcohol, sodium hypophosphite, 2-mercaptoethanol, and mixtures thereof. Also included are chain transfer agents of xanthate, dithiocarbonate, dithiocarbamate, trithiocarbonate type, and mixtures thereof. Preferably, it is sodium hypophosphite.

[0068] The amount of the chain transfer agent in the anionic water-soluble polymer is preferably 10 to 10,000 ppm, more preferably 50 to 5,000 ppm, based on the total mass of monomers A and B (+ optionally monomer C) of the anionic water-soluble polymer.

[0069] In a specific embodiment of the present invention, the anionic water-soluble polymer does not contain a chain transfer agent.

[0070] Physical properties of the water-soluble polymer The mass average molecular weight of the water-soluble polymer is preferably 1,000,000 to 25,000,000 Daltons, more preferably 2,000,000 to 15,000,000 Daltons, and even more preferably 3,000,000 to 10,000,000 Daltons. This is the mass average molecular weight.

[0071] The mass average molecular weight is preferably measured by gel permeation chromatography.

[0072] The anionic water-soluble polymer is obtained and used in liquid form.

[0073] The viscosity of the solution containing the anionic water-soluble polymer is preferably 1,000 to 50,000 cps, more preferably 5,000 to 20,000 cps.

[0074] Renewable origin In a preferred embodiment of the present invention, the anionic water-soluble polymer is prepared from compounds (monomers and / or compounds I and II) of at least partially renewable non-fossil origin.

[0075] In the context of the present invention, the term "renewable non-fossil origin" refers to the origin of chemical compounds derived from biomass or synthesis gas, i.e., the origin of chemical compounds that are the result of one or more chemical conversions performed on one or more raw materials having a natural and non-fossil origin. The terms "biosource" or "biore source" can also be used to characterize the renewable non-fossil origin of chemical compounds. The renewable non-fossil origin of a compound is derived from a circular economy and includes renewable non-fossil raw materials that have been recycled one or more times previously during a recycling process of biomass-derived materials such as materials derived from the depolymerization of polymers or the conversion of pyrolysis oil.

[0076] According to the present invention, "at least partially renewable non-fossil origin" means a biosource carbon content of preferably 5% to 100% by mass, preferably at least 30%, more preferably at least 50%, even more preferably at least 70%, even more preferably at least 90%, and even more preferably 100% biosource carbon, based on the total mass of carbon of the compound.

[0077] In the context of the present invention, the biosource properties of a chemical compound are characterized and the biosource carbon content of the compound is determined using Method B of ASTM D6866-21. The value is expressed as the mass percentage of biosource carbon relative to the total mass of carbon in the compound.

[0078] Gradient The anionic water-soluble polymer of the present invention is a gradient polymer.

[0079] A polymer having a gradient structure is a polymer containing at least two monomers, and is contrasted with block polymers in which the change in monomer composition is abrupt and random polymers that do not have a continuous change in composition. In a gradient polymer, the composition changes stepwise over the length of the polymer chain, resulting in less repulsion within and between the chains.

[0080] The gradient is formed by a spontaneous gradient or a forced gradient. Spontaneous gradient polymerization is due to differences in monomer reactivity. Forced gradient polymerization involves a change in the composition of the monomers introduced over the entire period of polymerization.

[0081] The forced method includes (1) introducing a first fraction of the monomers into the reactor, (2) adding at least one additional monomer fraction, preferably different from the first fraction, and (3) polymerizing the monomers introduced into the reactor. The polymerization of the monomers is initiated upon introduction of the first fraction.

[0082] The addition of the additional monomer fraction can be carried out in parallel with the introduction of the first fraction of the monomers into the reactor (thus, the introduction of the fractions can start and end simultaneously). Thus, the fractions can have different addition profiles in terms of flow rate, but the total addition period is the same. In fact, the flow rate of the addition of the fractions may or may not be constant over the entire addition period and may be continuous or discontinuous. Alternatively, the start of the supply of the first monomer (first fraction) to the reactor can precede the start of the addition of the second monomer fraction. Alternatively, the first fraction and the second fraction can be introduced simultaneously, but the addition period of the second fraction may be longer than the introduction period of the first fraction into the reactor. This embodiment is also applicable to methods using at least three fractions of monomers.

[0083] According to the method of the present invention, the resulting anionic water-soluble polymer is preferably formed by continuous addition of the monomers, in other words, by a forced gradient method.

[0084] The method according to the present invention comprises a first fraction (F1) and at least two additional fractions (F2 and F3). At least one of the fractions F1, F2, and F3 of this method is different from the other fractions. Preferably, the fractions F1, F2, and F3 are different from each other (F1≠F2≠F3). Different fractions refer to fractions having a composition of different monomers (ratio and / or properties of monomers) and / or compounds I and II (ratio and / or properties of compounds I and II).

[0085] Polymerization method The sequential preparation method of the anionic water-soluble polymer of the present invention comprises the following steps: a) A step of forming a solution (S1) containing at least one first fraction (F1) comprising (1) at least one monomer selected from monomers A and B and (2) at least one compound selected from compounds I and II; b) A polymerization step 1 (PO1) of fraction F1 to form a solution of the first gradient polymer (PG1); c) A step of adding a second fraction (F2) comprising (1) at least one monomer selected from monomers A and B and (2) at least one compound selected from compounds I and II to the solution containing PG1; d) A polymerization (PO2) step of fraction F2 in PG1 to form a solution of the second gradient polymer (PG2); e) A step of adding a third fraction (F3) comprising (1) at least one monomer selected from monomers A and B and (2) at least one compound selected from compounds I and II to the solution containing PG2; f) A polymerization step (PO3) of fraction F3 in PG2 to form a solution containing the anionic water-soluble polymer and At least one of fractions F1, F2, or F3 contains at least one monomer A, at least one of fractions F1, F2, or F3 contains at least one monomer B, at least one of fractions F1, F2, or F3 contains at least one compound I, and at least one of fractions F1, F2, or F3 contains at least one compound II.

[0086] This method can include the addition of additional fractions.

[0087] The improved performance of the water-soluble anionic polymer according to the present invention may be due to the fact that the polymerization is carried out continuously in sequence, i.e., without interruption.

[0088] "In sequence" means that the polymerization of the monomers of the anionic water-soluble polymer is carried out in a plurality of fractions without interruption, i.e., the addition of fractions is carried out continuously and the polymerization does not stop. Thus, the different steps a) to f) are carried out sequentially. In other words, a first fraction of monomers is poured (in a fluid form) and polymerized to form a first gradient polymer PG1, which is then polymerized with fraction F2 to form a gradient polymer PG2, and the gradient polymer PG2 itself is polymerized with fraction F3 to obtain an anionic water-soluble polymer at the end of the polymerization.

[0089] Preferably, at least one of fractions F1, F2, and F3 of this method is different from the other fractions. Preferably, fractions F1, F2, and F3 are different from each other (F1≠F2≠F3). By adding different fractions during the polymerization process, it is possible to create a gradient in the composition of the anionic water-soluble polymer.

[0090] In the polymerization method of the present invention, the sum of the molar percentages of the monomers of the different fractions is equal to the sum of the molar percentages of the monomers of the anionic water-soluble polymer.

[0091] Step a), formation of a solution (S1) containing a first fraction (F1) Solution (S1) Solution S1 preferably - a solvent, - an initiator, - and a first fraction F1 and consists of.

[0092] The solvent is preferably water or a solvent in which the monomer and the anionic water-soluble polymer are soluble. Preferably, the solvent is water.

[0093] The polymerization initiator used can be any compound that dissociates into radicals under the polymerization conditions, such as organic peroxides, hydroperoxides, hydrogen peroxide, persulfates, azo compounds, and redox pairs. The use of water-soluble initiators is preferred. In some cases, it is advantageous to use a mixture of various polymerization initiators, such as a mixture of a redox catalyst and an azo compound. Preferably, they are persulfates.

[0094] In a specific embodiment, solution S1 is formed by mixing the solvent, the initiator, and fraction F1 in a polymerization vessel.

[0095] In this specific embodiment, fraction F1 can be added to the solvent / initiator mixture all at once, in several portions, or (in a flowing form) gradually (e.g., by dropping). Preferably, fraction F1 is added to the polymerization vessel all at once.

[0096] In a specific embodiment of the present invention, the initiator and fraction F1 are poured (in a flowing form) into a polymerization vessel containing the solvent. They can be added separately or pre-mixed and added. Preferably, they are added separately.

[0097] In a preferred embodiment of the present invention, the initiator is added continuously over the course of the method (steps a) to f)). In this case, the initiator is preferably added in parallel with different fractions during different polymerization steps and during possible aging steps of different gradient polymers (PG1 and PG2) and anionic water-soluble polymers.

[0098] In this preferred embodiment of the present invention, the period for pouring the initiator is included in the range of 50 minutes to 560 minutes, preferably 130 minutes to 430 minutes.

[0099] First fraction (F1) Advantageously, fraction F1 contains 10 to 40% by mass, preferably 15 to 30% by mass, of monomers (A and / or B, + optionally C) with respect to the total mass of the monomers (A + B + optionally C) of the anionic water-soluble polymer.

[0100] Fraction F1 advantageously contains 0 to 50 mol%, preferably 0 to 35 mol%, of anionic monomer A with respect to the total number of moles of monomers in fraction F1.

[0101] Fraction F1 advantageously contains 50 to 100 mol%, preferably 65 to 100 mol%, of nonionic monomer B with respect to the total number of moles of monomers in fraction F1.

[0102] Fraction F1 advantageously contains 250 to 30,000 ppm, preferably 500 to 10,000 ppm, more preferably 1,000 to 7,000 ppm of compound I with respect to the total mass of monomers A and B (+ optionally monomer C) of the anionic water-soluble polymer.

[0103] Fraction F1 advantageously contains 250 to 30,000 ppm, preferably 500 to 10,000 ppm, more preferably 1,000 to 5,000 ppm of compound II with respect to the total mass of monomers A and B (+ optionally monomer C) of the anionic water-soluble polymer.

[0104] The various monomers and compounds constituting fraction F1 are advantageously added in the form of a solution. To form solution S1, these solutions can be added to the polymer container separately, as a mixture, all at once, or in several portions, or poured in (in a flowing form). The addition is preferably carried out all at once with the mixture.

[0105] When pouring fraction F1 (in a fluid form), it is advantageous to continue pouring for 10 to 80 minutes, preferably 40 to 70 minutes.

[0106] In a preferred embodiment, fraction F1 is prepared in the reactor (polymerization vessel) before the addition of the initiator.

[0107] In a preferred embodiment, fraction F1 contains at least one monomer B, at least one compound I, and at least one compound II.

[0108] Step b), polymerization of fraction F1 to form the first gradient polymer (PG1) Polymerization 1 (PO1) Before polymerization PO1, the atmosphere in the polymerization vessel can be replaced with an inert gas such as nitrogen or argon.

[0109] Polymerization PO1 is preferably a radical polymerization. A polymerization initiator, especially an initiator that dissociates into radicals under the polymerization conditions, can be used.

[0110] Polymerization PO1 is preferably started at a temperature of 70 to 90 °C, preferably 75 to 85 °C. The polymerization temperature is preferably controlled using cooling means so as not to exceed 95 °C.

[0111] Polymerization PO1 preferably continues for 10 to 80 minutes, preferably 40 to 70 minutes.

[0112] The polymerization preferably starts when the first monomer, solvent, and initiator come into contact. In other words, the period of polymerization PO1 preferably corresponds to the period of pouring fraction F1.

[0113] Gradient polymer (PG1) At the end of polymerization PO1, a gradient polymer (or prepolymer) PG1 is obtained.

[0114] In a specific embodiment of the present invention, the gradient polymer PG1 is aged for 5 to 60 minutes, preferably 10 to 30 minutes.

[0115] "Aging" means maintaining the temperature of the medium at 80 to 90 °C after the completion of polymerization in order to enable an increase in viscosity due to the internal branching phenomenon (branching) of the polymer. This definition of aging is relevant to all steps of the polymerization method.

[0116] Step c), addition of the second fraction (F2) to the solution containing PG1 The second fraction F2 Advantageously, fraction F2 contains 30 to 80% by mass, preferably 40 to 70% by mass of monomers (A and / or B, + optionally C) based on the total mass of the monomers of the anionic water-soluble polymer.

[0117] Fraction F2 advantageously contains 0 to 70 mol%, preferably 0 to 50 mol% of anionic monomer A based on the total number of moles of monomers in fraction F2.

[0118] Fraction F2 advantageously contains 30 to 100 mol%, preferably 65 to 100 mol% of nonionic monomer B based on the total number of moles of monomers in fraction F2.

[0119] Fraction F2 contains advantageously 250 to 30,000 ppm, preferably 500 to 10,000 ppm, more preferably 1,000 to 5,000 ppm of compound I based on the total mass of monomers A and B (+ optionally monomer C) of the anionic water-soluble polymer.

[0120] Fraction F2 contains advantageously 250 to 30,000 ppm, preferably 500 to 10,000 ppm, more preferably 1,000 to 5,000 ppm of compound II based on the total mass of monomers A and B (+ optionally monomer C) of the anionic water-soluble polymer.

[0121] The various monomers and compounds that make up F2 are advantageously added in the form of a solution. The solution can be added to the polymer container separately or as a mixture, all at once, in portions over several times, or in a flowing form. The addition is preferably carried out in a flowing form as a mixture.

[0122] Pouring fraction F2 advantageously continues for 10 to 100 minutes, preferably 30 to 90 minutes.

[0123] In a preferred embodiment, fraction F2 comprises at least one monomer A and B, at least one compound I, and at least one compound II.

[0124] Step d), Polymerization of fraction F2 in PG1 to form a second gradient polymer (PG2) Polymerization (PO2) Polymerization PO2 is carried out as an extension of polymerization PO1 and is carried out under the same temperature conditions (advantageously 70 - 90 °C).

[0125] Polymerization PO2 advantageously continues for 10 to 100 minutes, preferably 30 to 90 minutes.

[0126] Polymerization PO2 starts from the addition of the first monomer of fraction F2.

[0127] Advantageously, the duration of polymerization PO2 coincides with the duration of pouring fraction F2.

[0128] Gradient polymer (PG2) At the end of polymerization PO2, a gradient polymer (or prepolymer) PG2 is obtained.

[0129] In a particular embodiment of the invention, the gradient polymer PG2 is aged for 5 to 60 minutes, preferably 10 to 30 minutes.

[0130] Step e), Addition of a third fraction (F3) to the solution containing PG2 Fraction F3 Advantageously, fraction F3 contains 5 to 40% by weight, preferably 10 to 30% by weight, of monomers (A and / or B, + optionally C) based on the total weight of the monomers (A + B + optionally C) of the anionic water-soluble polymer.

[0131] Advantageously, fraction F3 contains 0 to 50 mol%, preferably 0 to 35 mol%, of anionic monomer A based on the total number of moles of monomers in fraction F3.

[0132] Advantageously, fraction F3 contains 50 to 100 mol%, preferably 65 to 100 mol%, of nonionic monomer B based on the total number of moles of monomers in fraction F3.

[0133] Advantageously, fraction F3 contains 0 to 10,000 ppm, preferably 10 to 5,000 ppm, more preferably 20 to 1,000 ppm, of compound I based on the total weight of monomers A and B (+ optionally monomer C) of the anionic water-soluble polymer.

[0134] Advantageously, fraction F3 contains 0 to 10,000 ppm, preferably 0 to 1,000 ppm, of compound II based on the total weight of monomers A and B (+ optionally monomer C) of the anionic water-soluble polymer.

[0135] The various monomers and compounds constituting F3 are advantageously added in the form of a solution. These solutions can be added to the polymer container separately or as a mixture, all at once, or in several portions, and can also be added in a flowing form, i.e., by dropping. The addition is preferably carried out in a flowing form with the mixture.

[0136] Pouring fraction F3 advantageously continues for 10 to 100 minutes, preferably 30 to 90 minutes.

[0137] In a preferred embodiment, fraction F3 contains at least one monomer B and at least one compound I.

[0138] Step f): Polymerization of fraction F3 in PG2 to form an anionic water-soluble polymer Polymerization (PO3) The polymerization PO3 is carried out as an extension of the polymerization PO2 and is carried out under the same time and temperature conditions as PO2 (advantageously 70 - 90 °C, 10 minutes - 100 minutes, preferably 30 minutes - 90 minutes).

[0139] The polymerization PO3 starts from the addition of the first monomer of fraction F3.

[0140] Advantageously, the period of the polymerization PO3 coincides with the period of pouring fraction F3.

[0141] At the end of the polymerization PO3, an anionic water-soluble polymer is obtained.

[0142] In a specific embodiment of the present invention, before removing the residual monomer, the anionic water-soluble polymer is aged for 5 minutes - 60 minutes, preferably 10 minutes - 30 minutes.

[0143] The reaction is advantageously stopped by the addition of an excess of initiator and / or water, and this step is used to remove the residual monomers that may be present in the solution containing the anionic water-soluble polymer.

[0144] Any step The method according to the present invention can further include additional steps and is not limited to the steps described above.

[0145] In a specific embodiment of the present invention, the polymerization method of the present invention can include the addition of additional fractions that make up the final anionic water-soluble polymer.

[0146] In a preferred embodiment of the present invention, the anionic water-soluble polymer is aged for 10 minutes - 100 minutes, preferably 30 minutes - 90 minutes, after the step f) of the polymerization PO3. When adding additional fractions, the aging is carried out after the last polymerization step.

[0147] In certain embodiments of the present invention, a crosslinking agent and / or a migrating agent is added during at least one of the above-described steps.

[0148] In a preferred embodiment of the present invention, the crosslinking agent is added to fraction F1 and / or fraction F2.

[0149] When a crosslinking agent is added, it is advantageously selected from the crosslinking agents described above.

[0150] When a crosslinking agent is added, the amount is advantageously 5 to 5,000 ppm, preferably 50 to 3,000 ppm, based on the total mass of the anionic water-soluble polymer (monomers A, B, and optionally C).

[0151] In a preferred embodiment of the present invention, the migrating agent is added to fraction F1 and / or fraction F2.

[0152] When a migrating agent is added, it is advantageously selected from the migrating agents described above.

[0153] When a migrating agent is added, the amount is advantageously 10 to 10,000 ppm, preferably 50 to 5,000 ppm, based on the total mass of the anionic water-soluble polymer (monomers A, B, and optionally C).

[0154] Advantageously, the anionic water-soluble polymer obtained according to the method of the present invention is used without post-treatment other than salting of the polymer. It can be used in solution (without drying or prior purification) or after drying, immediately after step f) or after one or more optional steps.

[0155] Paper manufacturing method The present invention also relates to a method for producing paper or cardboard, comprising (1) adding an anionic water-soluble polymer according to the present invention to an aqueous suspension of fibers (advantageously cellulose fibers) and (2) forming a sheet of paper or cardboard. Thus, the present invention relates to the use of an anionic water-soluble polymer in a paper manufacturing method.

[0156] The various processes of the method for manufacturing paper, cardboard, etc. are known according to techniques that utilize the knowledge of those skilled in the art, and since they are known and conventional from the perspective of the knowledge of those skilled in the art, there is no need for further detailed explanation. If necessary, the following literature: Handbook for Pulp & Paper Technologists, 3 rd rd Edition, G. A. Smook can be referred to.

[0157] According to the present invention, the anionic water-soluble polymer is added in the papermaking process before or after forming a sheet of paper, cardboard, etc. Therefore, the contact between the cellulose material and the polymer of the present invention can be carried out in various ways, particularly according to typical methods known to those skilled in the art.

[0158] The anionic water-soluble polymer can be added to the cellulose material in the form of a diluted aqueous solution or an undiluted aqueous solution. It can also be applied by an impregnation technique, or directly added to the fiber suspension at any point in the method of manufacturing paper where a dry strength enhancer is usually introduced.

[0159] Therefore, the polymer according to the present invention can be introduced into a thick pulp (referred to as "thick stock" in English) or a diluted pulp (referred to as "thin stock" in English). It can be added with a mixing pump before the headbox or the filter screen. Preferably, the polymer is introduced before the headbox.

[0160] Preferably, the polymer according to the present invention is industrially injected into the fiber suspension, that is, before being diluted with pulp water (thick pulp). The concentration of the pulp is about 1 to 5% by mass of the cellulose fibers.

[0161] The papermaking method according to the present invention can be used for any type of paper pulp such as raw fiber pulp (kraft, sulfite), recycled fiber pulp, deinked pulp, mechanical pulp, and thermomechanical pulp.

[0162] In a preferred embodiment of the present invention, the anionic water-soluble polymer of the present invention is added in combination with a cationic water-soluble polymer in order to enhance the dry strength properties of paper while maintaining good drainage performance.

[0163] The cationic water-soluble polymer is preferably selected from PAE (polyaminopolyamide epichlorohydrin), polyvinylamine, glyoxylated polyacrylamide, PEI (polyethyleneimine), PA (polyamine, epichlorohydrin-dimethylamine resin), polymers obtained by Hofmann degradation, polyacrylamide, starch, and mixtures thereof. Polymers obtained by Hofmann degradation are preferred.

[0164] Advantageously, the mass ratio of the anionic water-soluble polymer of the present invention to the cationic water-soluble polymer is included in the range of 1 / 10 to 10 / 1.

[0165] The anionic water-soluble polymer and the cationic water-soluble polymer are advantageously added directly to the fiber suspension before sheet formation.

[0166] These can be added separately or as a mixture, and can be added by one-point or two-point injection in any order of introduction.

[0167] The papermaking method according to the present invention can also include the addition of other additives and / or polymers as required, and examples include, but are not limited to, biocides, coagulants, crosslinking agents, flocculants, starch, and the like.

[0168] Use The present invention also relates to the use of an anionic water-soluble polymer in the recovery of hydrocarbons (oil and / or gas); in well drilling or cementing; in hydrocarbon wells (oil and / or gas), for example, in hydraulic fracturing, conditioning, and diversion stimulation; in the treatment of water in open, closed, or semi-closed circulation; in the treatment of fermentation products; in the treatment of sludge; in construction; in the treatment of wood; in the treatment of hydraulic compositions (concrete, cement, mortar, and aggregates); in the mining industry; in the formulation of cosmetic products; in the battery industry; in the formulation of surfactants; in the manufacture of textiles; in geothermal technology; in the manufacture of diapers; or in agriculture.

[0169] The present invention also relates to the use of an anionic water-soluble polymer as a flocculant, coagulant, binder, solidifying agent, viscosity reducer, thickener, absorbent, friction reducer, drainage agent, filler retainer, dehydrating agent, condition regulator, stabilizer, solidifying agent, film-forming agent, sizing agent, high-performance water reducer, clay inhibitor, or dispersant.

[0170] The present invention and the advantages derived therefrom will become more apparent in the following non-limiting examples given to illustrate the present invention.

Examples

[0171] List of Abbreviations AMD: Acrylamide (Monomer B) AA: Acrylic acid (Monomer A) DMAM: Dimethylacrylamide (Compound II) SMS: Sodium methallylsulfonate (Compound I) SPS: Sodium persulfate (Polymerization initiator) ATBS: 2-Acrylamido-2-methylpropanesulfonic acid (Monomer A) IA: Itaconic acid (Monomer A) DMAEMA: Dimethylaminoethyl methacrylate (Cationic polymer)

[0172] Description of GPC-Malls Characterization of Molecular Weight Gel permeation chromatography is a method that enables the separation of polymers as a function of their hydrodynamic volume and, when coupled with a Malls detector, enables the measurement of light scattering at multiple angles.

[0173] Synthetic polymers are analyzed under the following conditions. - Equipment: GPC-2 - Columns: Shodex SB-807-HQ & SB-805 custom - Method: * Temperature: 30 °C * Mobile phase: 0.5 M NaNO 3 , HEPES (pH = 8), 100 ppm NaN 3 * Injection: 100 μL * Flow rate: 0.3 mL / min * Detection: (i) Light scattering detector (MALS): Absolute molar mass (ii) Refractive index measurement (RI): Focusing type Viscosity is measured using a Brookfield viscometer at 25 °C with a Brookfield LV3 module speed of 6 rpm.

[0174] Preparation of Polymers 1 to 5 (P1 to P5(INV)) of the Present Invention Polymer 1 (P1) First sequence: Gradient polymer or prepolymer PG1 Into a 1-liter reactor equipped with a mechanical stirrer, thermometer, cooler, and gas nitrogen immersion rod, introduce as starting materials a first fraction F1 consisting of 165.6 g of water, 71.2 g of acrylamide (50% by mass in water), 1 g of citric acid, 0.5 g of dimethylacrylamide, and 0.68 g of sodium methallylsulfonate. Heat the medium and maintain it at a temperature of 79 - 81 °C in a water bath. By adding 0.05 g of sodium persulfate, this starting material can be initiated to start the polymerization (PO1) of the monomer and form the first gradient polymer PG1.

[0175] Second sequence: Gradient polymer or prepolymer PG2 When the exothermic reaction ends, the initiator (30 g of SPS at 0.33 mass% in water) is added for 130 minutes while simultaneously starting to flow a second fraction F2 consisting of 28.8 g of water, 124.9 g of acrylamide (50 mass% in water), 23 g of 100% acrylic acid, 0.5 g of dimethacrylamide, and 0.33 g of sodium methallyl sulfonate over 50 minutes. After pouring fraction F2, the gradient polymer PG2 is aged for 10 minutes (while pouring fraction F2 and during aging, the polymerization PO2 for forming the gradient polymer PG2 is carried out).

[0176] Third sequence: Polymer 1 (P1) Thereafter, a third fraction F3 consisting of 136.8 g of water, 61.1 g of acrylamide (50 mass% in water), and 0.01 g of sodium methallyl sulfonate is flowed over 60 minutes. At the end of the addition of fraction F3, the polymer is aged for 10 minutes (while pouring fraction F3 and during aging, the polymerization PO3 for forming the polymer is carried out). After aging is complete, 165.3 g of water and 0.15 g of sodium persulfate are added. When the desired viscosity is achieved, the reaction is terminated by adding 2.4 g of sodium bisulfite (40 mass% in water) and 165.2 g of water. Before cooling, further aging for 60 minutes is carried out. The solution containing polymer 1 (P1) has a pH of 3.5, an active substance of 15 mass%, a viscosity of 8,900 cps, and a molecular weight of 4,580,000 Da obtained by GPC-Malls.

[0177] Polymers 2 - 5 of the present invention (P2 - P5(INV)) The protocol for preparing polymer 1 (P1) is reproduced while varying the composition of the various fractions to produce polymers 2 - 5 (P2 - P5). The compositions of the various fractions used to obtain these polymers are summarized in Table 1.

[0178] Preparation of comparative polymers 6 - 11 (CE1 - CE6) Polymer 6 (CE1) This polymer is prepared in one sequence. 663.7 g of water, 262.9 g of acrylamide (50% by mass in water), 23.5 g of 100% acrylic acid, 0.5 g of dimethylacrylamide, and 0.65 g of sodium methallylsulfonate are introduced into a 1-liter reactor equipped with a mechanical stirrer, thermometer, cooler, and gas nitrogen immersion rod. The pH is adjusted to 6 by adding 23 g of NaOH (50% by mass in water). The reactor is heated to 35 °C. The reaction is initiated by adding 0.16 g of VA044.

[0179] Once the maximum temperature is reached, it is aged for 60 minutes before adding 2.4 g of sodium bisulfite (40% by mass in water). It is aged for an additional 60 minutes before cooling. The solution containing the counterexample polymer 6 (CE1) has a pH of 7, an active substance of 15% by mass, a viscosity of 7,000 cps, and a molecular weight of 1,400,000 Da obtained by GPC-Malls.

[0180] Polymer 7 (CE2) While changing the monomer composition of the polymer, polymer 7 is prepared according to the same protocol as polymer 6.

[0181] Polymer 8 (CE3) Polymer 8 is prepared according to the same protocol as polymer 1 (i.e., in three sequences), except that a polymer is obtained without containing compound II (DMAM).

[0182] Polymer 9 (CE4) Polymer 9 (CE4) is prepared according to the same protocol as polymer 1 (i.e., in three sequences), except that it does not contain compound I (SMS) and II (DMAM), but a polymer is obtained in the presence of sodium hypophosphite (Hypo) as a transfer agent.

[0183] Polymer 10 (CE5) Polymer 10 (CE5) is prepared according to the same protocol as polymer 1, but in only two sequences.

[0184] Polymer 11 (CE6) While changing the monomer composition of the polymer, Polymer 11 (CE6) is prepared according to the same protocol as Polymer 1 (i.e., in three sequences).

[0185] The compositions of the different fractions of the preparation methods of Polymers 1 to 11 are summarized in Table 1a (Table 1).

[0186] In Table 1a (Table 1), the monomer content represents the molar mass percentage of the AMD (or AA, ATBS, or IA) monomer with respect to the total molar mass of the corresponding monomer in the whole fraction. Therefore, for example, the sum of the percentages of the AMD monomer in the three fractions is equal to 100%.

[0187] The contents of Compound I (SMS) and II (DMAM) are expressed in mass ppm with respect to the total mass of the monomers in the three fractions.

[0188] [Table 1]

[0189] The physicochemical properties of the obtained polymers are described in Table 1b (Table 2) below.

[0190] [Table 2]

[0191] Table 2 (Table 3) summarizes the compositions of the different fractions (monomers A and B, Compounds I and II) for preparing Polymers P1 to P5 (INV) and CE1 to CE6.

[0192] [Table 3]

[0193] Application test Polymers 1 to 11 are used in combination with the following cationic polymers. HF31: A polymer of the SNF line, polyvinylamine obtained by Hofmann degradation, cationic, having a viscosity of 200 cps and a dry extract of 21% by mass. VP450: A polymer of the SNF line, polyvinylamine obtained by hydrolysis of polyvinylformamide, cationic, having a viscosity of 1,380 cps and a dry extract of 19.2% by mass.

[0194] The drainage and dry strength performance of Polymers 1 to 11 in combination with HF31 and VP450 are evaluated according to the following conditions.

[0195] To obtain a final aqueous concentration of 1% by mass, the wet pulp used in all application examples is obtained by decomposition of dry pulp. This is pulp at neutral pH consisting of 100% recycled paper fibers.

[0196] Evaluation of vacuum drainage performance (DDA) The DDA ("Dynamic Drainage Analyzer") can automatically determine the time (in seconds) required to drain the fiber suspension on the cloth under vacuum. The polymer is added to the wet pulp (0.6 liter of pulp at 1.0% by mass) in the cylinder of the DDA under stirring at 1,000 rpm. T = 0 s: Stirring of the pulp T = 10 s: Addition of the polymer T = 30 s: Stopping of stirring and vacuum drainage at 200 mbar for 60 s

[0197] The pressure under the cloth is recorded as a function of time. When all the water is removed from the fiber mat, air passes through the mat, causing a change in the slope of the curve representing the pressure under the cloth as a function of time. The time represented by the number of seconds recorded in this change in slope corresponds to the drainage time. The shorter the time, the better the vacuum drainage.

[0198] Weighing 80 g.m -2Performance in drying strength applications Ultimately, the necessary amount of pulp is recovered so that a sheet with a basis weight of 80 g / m² is obtained. -2

[0199] The wet pulp is introduced into the vat of the dynamic sheet former and maintained under agitation. The various components of the system are injected into this pulp according to a pre-defined sequence. Usually, a contact time of 30 - 45 seconds is observed each time a polymer is added.

[0200] The paper sheet former is equipped with an automatic dynamic sheet former. Before starting the rotation of the drum at 1,000 rpm, blotting paper and forming cloth are placed on the drum of the dynamic sheet former to form a water wall. The treated pulp is dispersed throughout the water wall to form a fiber mat on the forming cloth.

[0201] After draining, the fiber mat is recovered, compressed with a 4 bar press, and dried at 117 °C. The resulting sheet is conditioned overnight in a room where the humidity and temperature are controlled (relative humidity 50%, 23 °C). The drying strength properties of all the sheets obtained by this procedure are measured.

[0202] Bursting is measured using a Messmer Buchel M 405 bursting tester according to TAPPI standard T403 om - 02.

[0203] The dry breaking length is measured in the machine direction using a Testometric AX traction device according to TAPPI standard T494 om - 01.

[0204]

Table 4

[0205] ​The polymers (1 - 5) of the present invention, when combined with a cationic polymer, are found to have improved drainage performance (DDA) and mechanical properties (Burst: rupture, DBL: dry break) compared to polymers produced by conventional methods (polymers 6 and 7), in the absence of a structuring system (polymers 8 and 9), in the absence of a third fraction (polymers 10), or in the presence of a cationic monomer (polymers 11), which is interesting.

Claims

1. - At least one anionic monomer A, - At least one nonionic monomer B, - At least one structuring system An anionic water-soluble polymer comprising: At least one structuring system is (i) At least one compound I selected from allylsulfonic acid, methallylsulfonic acid, allyldisulfonic acid, methallyldisulfonic acid, salts thereof, and mixtures thereof, which is different from at least one monomer A, (ii) At least one compound II of formula II that is different from at least one monomer B: 【Chemical 1】 (wherein R 1 and R 2 are, independently of each other, a hydrogen atom, a methyl group, an ethyl group, an isopropyl group, or a CH 2 -OH group, R 1 and R 2 are not both hydrogen atoms) Compound II as shown Comprising, The polymer does not contain cationic monomers and zwitterionic monomers, The anionic water-soluble polymer is obtained by the following steps: a) A step of forming a solution (S1) containing a first fraction (F1) comprising (1) at least one monomer selected from monomer A and monomer B and (2) at least one compound selected from compound I and compound II; b) A polymerization step 1 (PO1) of fraction F1 to form a solution of the first gradient polymer (PG1); c) A step of adding a second fraction (F2) comprising (1) at least one monomer selected from monomer A and monomer B and (2) at least one compound selected from compound I and compound II to the solution containing PG1; d) A polymerization step 2 (PO2) of fraction F2 in PG1 to form a solution of the second gradient polymer (PG2); e) A step of adding a third fraction (F3) comprising (1) at least one monomer selected from monomer A and monomer B and (2) at least one compound selected from compound I and compound II to the solution containing PG2; f) A polymerization step 3 (PO3) of fraction F3 in PG2 to form a solution containing the anionic water-soluble polymer Obtained by, At least one of fraction F1, F2, or F3 contains at least one monomer A, at least one of fraction F1, F2, or F3 contains at least one monomer B, at least one of fraction F1, F2, or F3 contains at least one compound I, at least one of fraction F1, F2, or F3 contains at least one compound II, The anionic water-soluble polymer does not contain a cross-linking agent, An anionic water-soluble polymer.

2. The anionic water-soluble polymer according to claim 1, wherein at least one anionic monomer A is selected from acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, acrylamide undecanoic acid, 3-acrylamido-3-methylbutanoic acid, maleic anhydride, 2-acrylamido-2-methylpropanesulfonic acid (ATBS), vinylsulfonic acid, vinylphosphonic acid, 2-sulfoethyl methacrylate, sulfopropyl methacrylate, sulfopropyl acrylate, allylphosphonic acid, styrenesulfonic acid, 2-acrylamido-2-methylpropanedisulfonic acid, salts thereof, and mixtures thereof.

3. At least one nonionic monomer B is selected from acrylamide, methacrylamide, N-vinylformamide (NVF), N-vinylacetamide, N-vinylpyrrolidone (NVP), N-vinylimidazole, N-vinylsuccinimide, acryloylmorpholine (ACMO), acryloyl chloride, glycidyl methacrylate, glyceryl methacrylate, diacetone acrylamide, hydroxyalkyl (meth)acrylate, thioalkyl (meth)acrylate, and mixtures thereof, wherein the alkyl is C 1 ~C 3 The anionic water-soluble polymer according to claim 1 or 2, characterized in that it is as described above.

4. The anionic water-soluble polymer according to any one of claims 1 to 3, comprising 500 to 50,000 ppm of compound I based on the total mass of monomers A and B.

5. The anionic water-soluble polymer according to any one of claims 1 to 4, comprising 500 to 50,000 ppm of compound II based on the total mass of monomers A and B.

6. The anionic water-soluble polymer according to any one of claims 1 to 5, wherein compound II is selected from N,N-dimethacrylamide, N,N-diethylacrylamide, N,N-isopropylacrylamide, N-methylolacrylamide, and mixtures thereof.

7. The anionic water-soluble polymer according to any one of claims 1 to 6, wherein the mass ratio of compound I to compound II is included in the range of 0.01 to 100.

8. A method for the sequential preparation of an anionic water-soluble polymer, wherein the anionic water-soluble polymer comprises - at least one anionic monomer A, and - at least one nonionic monomer B, and - at least one structuring system, (i) at least one compound I selected from allylsulfonic acid, methallylsulfonic acid, allyldisulfonic acid, methallyldisulfonic acid, salts thereof, and mixtures thereof, which is different from at least one monomer A, and (ii) at least one compound II of formula II: 【Chemical 2】 (wherein, R 1 and R 2 are each independently a hydrogen atom, a methyl group, an ethyl group, an isopropyl group, or a CH 2 -OH group, R 1 and R 2 are not both hydrogen atoms (when R 2 = H, R 1 ≠ H; when R 1 = H, R 2 ≠ H)) and including at least one structuring system, and the polymer does not contain cationic monomers and zwitterionic monomers, The method comprises the following steps: a) A step of forming a solution (S1) comprising at least a first fraction (F1), the first fraction (F1) comprising at least one monomer selected from monomer A and monomer B and at least one compound selected from compound I and compound II; b) A polymerization step 1 (PO1) of fraction F1 to form a solution of a first gradient polymer (PG1); c) A step of adding a second fraction (F2) comprising at least one monomer selected from monomer A and monomer B and at least one compound selected from compound I and compound II to the solution containing PG1; d) A polymerization (PO2) step of fraction F2 in PG1 to form a solution of a second gradient polymer (PG2); e) A step of adding a third fraction (F3) comprising at least one monomer selected from monomer A and monomer B and at least one compound selected from compound I and compound II to the solution containing PG2; f) A polymerization step (PO3) of fraction F3 in PG2 to form a solution containing an anionic water-soluble polymer comprising at least one of fraction F1, F2, or F3 contains at least one monomer A, at least one of fraction F1, F2, or F3 contains at least one monomer B, at least one of fraction F1, F2, or F3 contains at least one compound I, and at least one of fraction F1, F2, or F3 contains at least one compound II, Method. **Claim 9** The method according to claim 8, characterized in that the initiator is continuously added throughout the method. **Claim 10** The method according to claim 8 or 9, characterized in that after the polymerization step (PO3) in step f), an aging step of 10 to 100 minutes is included. **Claim 11** A method for manufacturing paper or cardboard, comprising a step of adding the anionic water-soluble polymer according to any one of claims 1 to 7 to an aqueous suspension of fibers, and a step of forming a sheet of paper or cardboard. **Claim 12** Use of the anionic water-soluble polymer according to any one of claims 1 to 7 in the recovery of hydrocarbons; in well drilling or cementing; in stimulating hydrocarbon wells; in the treatment of water in open, closed, or semi-closed circulation; in the treatment of fermentation products; in the treatment of sludge; in construction; in the treatment of wood; in the treatment of hydraulic compositions; in the mining industry; in the formulation of cosmetic products; in the battery industry; in the formulation of surfactants; in the manufacture of textiles; in geothermal technology; in the manufacture of diapers; or in agriculture.

13. Use of the anionic water-soluble polymer according to any one of claims 1 to 7 as a flocculant, coagulant, binder, solidifying agent, viscosity reducer, thickener, absorbent, friction reducer, drainage agent, filler retainer, dehydrating agent, condition regulator, stabilizer, solidifying agent, film-forming agent, sizing agent, high-performance water reducer, clay inhibitor, or dispersant.

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