Novel polymer and preparation method thereof

Abstract

The invention relates to a novel anionic water-soluble polymer as well as a preparation method and application thereof, in particular to the field of papermaking.

Description

Technical Field

[0001] The invention relates to a novel anionic water-soluble polymer, a preparation method and application thereof, especially application in the field of papermaking. Background Art

[0002] The paper industry is constantly seeking to improve its processes for producing paper, board or the like, particularly with regard to cost reduction, yield, productivity and the quality of the final product.

[0003] This is especially true for the packaging industry which seeks paper, paperboard or the like with better dry strength properties, in particular in order to address current ecological issues and to replace plastic packaging. This search for improvements should not be at the expense of productivity.

[0004] By definition, the dry strength of paper is the strength of paper, board or the like in the dry state. Traditionally, mechanical strength values ​​provide a measure of dry strength. One can speak of, among others, bursting strength, tensile strength, compressive strength, delamination strength…

[0005] It is known to use water-soluble cationic polymers in order to improve the strength properties of paper. Due to their properties, these polymers can directly attach to anionic cellulose and impart a cationic charge to it, so that the anionic cellulose binds to the anionic polymer, which attaches to the cellulose fibers, thereby improving the dry strength of the paper.

[0006] JP 2012 251252 discloses a papermaking method involving an amphoteric polymer.

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

[0008] Such combinations of cationic polymers and anionic polymers for increasing dry strength are well known. In particular, in document FR 2880901 B1 it has been proposed to combine cationic polymers with anionic polymers, the purpose of which is to provide an effective system for the dry strength of paper.

[0009] The problem with this combination between the two polymers in solution is a loss of drainage properties of the paper. By reducing the drainage properties, the speed of the paper machine is reduced, which leads to a significant drop in productivity.

[0010] This problem is mainly due to anionic polymers that are synthesized by liquid processes and have low molecular weight. In liquid processes, an increase in molecular weight leads to an increase in viscosity. Above a certain molecular weight, it is no longer possible to obtain a liquid.

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

[0012] There are many disadvantages to using polymers in solid form, such as:

[0013] -Manufacturers are obliged to have an on-site powder dilution system;

[0014] -Increase the size of the device, thereby increasing its footprint;

[0015] - Increased energy consumption and maintenance;

[0016] -Management of powder inventory;

[0017] - Management of initial dissolution of powders;

[0018] -More frequent and complex maintenance.

[0019] The main problem remains the dissolution of high molecular weight polymer powders. In fact, the dissolution of such polymers is critical and requires technical knowledge in order to avoid the risk of poor dissolution which would lead to the formation of aggregates on the paper, thus weakening the paper, or even worse, to machine fouling, which could lead to a complete stop and maintenance of the entire production unit. Moreover, such high molecular weight polymers in powder form can lead to excessive flocculation and have a negative impact on the formation of the paper, which has a negative impact on the mechanical properties of the paper.

[0020] Manufacturers have been searching for a solution which makes it possible to obtain paper having good dry strength properties while maintaining satisfactory drainage characteristics and which simplifies its installation thanks to the use of polymers in liquid form.

[0021] The Applicant has surprisingly found that the synthesis of polymers according to the process of the invention makes it possible to meet the needs of manufacturers without penalising the latter.

[0022] The use of polymers derived from the invention is part of a general principle of improving product properties, more specifically dry strength and drainage characteristics. The better properties of the polymers according to the invention make it possible to reduce the amount of product required for an application, which therefore means a reduction in the emissions of greenhouse gases (such as CO2) associated with the production and use of synthetic polymers. Summary of the invention

[0023] The present invention relates to an anionic water-soluble polymer, comprising:

[0024] - at least one anionic monomer A;

[0025] - at least one nonionic monomer B;

[0026] - At least one structured system comprising:

[0027] (i) at least one compound I different from at least one monomer A, which is selected from the group consisting of allylsulfonic acid, methallylsulfonic acid, allyldisulfonic acid, methallyldisulfonic acid, salts thereof and mixtures thereof;

[0028] (ii) at least one compound II of the formula II which is different from at least one monomer B:

[0029]

[0030] R1 and R2 are independently a hydrogen atom, a methyl group, an ethyl group, an isopropyl group or a CH2-OH group;

[0031] R1 and R2 are not both hydrogen atoms (when R2=H, R1≠H; when R1=H, R2≠H).

[0032] The anionic water-soluble polymer is obtained according to the following steps:

[0033] a) forming a solution (S1) comprising a first part (F1) containing (1) at least one monomer selected from monomers A and B and (2) at least one compound selected from compounds I and II;

[0034] b) subjecting part F1 to polymerization 1 (PO1) so as to form a solution of a first gradient polymer (PG1);

[0035] c) adding a second part (F2) containing (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 comprising PG1;

[0036] d) polymerizing part F2 on PG1 (PO2) to form a solution of a second gradient polymer (PG2);

[0037] e) adding a third part (F3) containing (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 comprising PG2;

[0038] f) polymerizing part F3 on PG2 (PO3) to form a solution comprising an anionic water-soluble polymer and

[0039] At least one of the fractions F1, F2 or F3 contains at least one monomer A, at least one of the fractions F1, F2 or F3 contains at least one monomer B, at least one of the fractions F1, F2 or F3 contains at least one compound I and at least one of the fractions F1, F2 or F3 contains at least one compound II.

[0040] The anionic water-soluble polymer does not contain cationic monomers and zwitterionic monomers.

[0041] In the present invention, the first and second gradient polymers are prepolymers.

[0042] The present invention also relates to a method for preparing the anionic water-soluble polymer. This is a stepwise polymerization method.

[0043] The invention also relates to a process for producing paper and paperboard using the anionic water-soluble polymer.

[0044] The invention also relates to the use of the anionic water-soluble polymers in the recovery of hydrocarbons (oil and / or gas); in drilling or cementing wells; in the stimulation of hydrocarbon wells (oil and / or gas), for example hydraulic fracturing, conformance, diversion; in the treatment of water in open, closed or semi-closed cycles; in the treatment of fermented mash, in the treatment of sludges; in construction; in wood treatment; in the treatment of hydraulic compositions (concrete, cement, mortar and aggregates); in the mining industry; in the formulation of cosmetics; in the battery field; in the formulation of detergents; in textile production; in geothermal technology; in diaper production; or in agriculture.

[0045] The present invention also relates to the use of the anionic water-soluble polymer as a flocculant, coagulant, adhesive, fixative, viscosity reducer, thickener, absorbent, friction reducer, drainage agent, filler retention agent, dehydrating agent, regulator, stabilizer, fixative, film former, sizing agent, superplasticizer, clay inhibitor or dispersant. DETAILED DESCRIPTION

[0046] "Polymer" means a copolymer prepared from at least two different monomers with at least one anionic monomer A and at least one nonionic monomer B and from a structuring system comprising at least one compound I and at least one compound II. It may optionally contain at least one hydrophobic monomer and / or a crosslinker and / or a transfer agent.

[0047] A water-soluble polymer is understood to mean a polymer which is soluble in water at 10 g·L at 25°C. -1 A polymer that, when dissolved in deionized water with stirring, produces an aqueous solution free of insoluble particles.

[0048] Throughout the specification, viscosity is measured in aqueous solution at 25°C using a Brookfield viscometer with a Brookfield LV3 module.

[0049] In this description, the skilled person is regarded as being able to determine the appropriate module and speed of the Brookfield viscometer according to the viscosity range to be measured. This type of measurement is in fact part of the common general knowledge of the skilled person.

[0050] According to the present invention, "X and / or Y" is understood to mean "X" or "Y" or "X and Y".

[0051] Another part of the present invention is all possible combinations between different disclosed embodiments, whether they are preferred embodiments or embodiments given as examples. In addition, when numerical ranges are indicated, the limits are part of these ranges. The present disclosure also includes all combinations in the limits of these numerical ranges. For example, the numerical range "1-20, preferably 5-15" means the disclosure of the ranges "1-5", "1-15", "5-20" and "15-20" and the numerical values ​​1, 5, 15 and 20.

[0052] Anionic water-soluble polymer

[0053] The anionic water-soluble polymer according to the present invention comprises:

[0054] - at least one anionic monomer A;

[0055] - at least one nonionic monomer B;

[0056] - At least one structured system comprising:

[0057] (i) at least one compound I different from at least one monomer A, which is selected from the group consisting of allylsulfonic acid, methallylsulfonic acid, allyldisulfonic acid, methallyldisulfonic acid, salts thereof and mixtures thereof;

[0058] (ii) at least one compound II of the formula II which is different from at least one monomer B:

[0059]

[0060] R1 and R2 are independently a hydrogen atom, a methyl group, an ethyl group, an isopropyl group or a CH2-OH group;

[0061] R1 and R2 are not both hydrogen atoms (when R2=H, R1≠H; when R1=H, R2≠H).

[0062] The polymer is free of cationic monomers and zwitterionic monomers.

[0063] Monomer components

[0064] The anionic water-soluble polymers according to the present invention are synthetic polymers which may comprise one or more anionic monomers (referred to as "monomer(s) A").

[0065] Advantageously, this anionic monomer or other anionic monomer A can be selected in a large group. These monomers can have vinyl functional groups, especially acrylic acid, maleic acid, fumaric acid, malonic acid, itaconic acid or allyl functional groups. They can also contain carboxylate, phosphonate, phosphate, sulfonate or another anionic charge group. The preferred monomer belonging to this class is, for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, acrylamido undecanoic acid, 3-acrylamide-3-methylbutyric acid, maleic anhydride, 2-acrylamide-2-methylpropanesulfonic acid (ATBS), vinyl sulfonic acid, vinylphosphonic acid, 2-sulfoethyl methacrylate, sulfopropyl methacrylate, sulfopropyl acrylate, allylphosphonic acid, styrene sulfonic acid, 2-acrylamide-2-methylpropane disulfonic acid, its salt and mixture thereof. Preferably, these monomers are acrylic acid or itaconic acid, even more preferably acrylic acid.

[0066] Thus, in a particular embodiment of the invention, one or more anionic monomers A can be salified.

[0067] Salt formation is understood to mean the replacement of at least one proton of the acid function of the -R(O)-OH (R=P, S or C) type of anionic monomer A by a metal cation to form a salt of the -R(O)-OX (X is a metal cation). In other words, the non-salted form corresponds to the acid form of the monomer, for example RC(=O)-OH in the case of a carboxylic acid function, while the salted form of the monomer corresponds to RC(=O)-OX + Form, X + The acid functional groups of the water-soluble polymer may be partially or completely salted, corresponding to the alkali metal cations.

[0068] The salified form advantageously corresponds to a salt of an alkali metal (Li, Na, K . . . ), an alkaline earth metal (Ca, Mg . . . ) or ammonium (eg ammonium ion or tertiary ammonium). The preferred salt is the sodium salt.

[0069] The salt formation can be carried out before or after the polymerization.

[0070] The anionic water-soluble polymer advantageously comprises from 1 to 99 mol %, preferably from 2 to 70 mol %, more preferably from 3 to 50 mol %, even more preferably from 5 to 35 mol % of one or more anionic monomers A.

[0071] In a specific embodiment of the present invention, when the anionic monomer A is 2-acrylamido-2-methylpropanesulfonic acid, the anionic monomer A is a hydrated form of 2-acrylamido-2-methylpropanesulfonic acid. The hydrated form of ATBS is a special form of ATBS, and the hydrated form of ATBS can be obtained by controlled crystallization of the ATBS monomer. Document US10,759,746 describes the hydrated form of ATBS.

[0072] The anionic water-soluble polymer may comprise one or more nonionic monomers (referred to as "monomer(s) B").

[0073] Advantageously, the one or more nonionic monomers B can be selected in particular from the group comprising 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, (meth) hydroxyalkyl acrylate (C1-C3 alkyl), (meth) thioalkyl acrylate (C1-C3 alkyl) and mixtures thereof. Preferably, the monomer is acrylamide.

[0074] The anionic water-soluble polymer advantageously comprises from 1 to 99 mol %, preferably from 30 to 98 mol %, more preferably from 50 to 97 mol %, even more preferably from 65 to 95 mol % of nonionic monomers B.

[0075] The anionic water-soluble polymer may optionally comprise one or more hydrophobic monomers (referred to as "one or more monomers C").

[0076] Advantageously, the one or more hydrophobic monomers C may be selected from the group consisting of: 30 Alkyl, arylalkyl (C4-C 30 Alkyl, C4-C 30 (meth)acrylates having a propoxylated, ethoxylated, or ethoxylated and propoxylated (meth)acrylate chain; having a C1-C3 alkyl, an arylalkyl (C4-C 30 Alkyl, C4-C 30 Aryl) or dialkyl (C4-C 30 (meth)acrylamide derivatives having propoxylated, ethoxylated or ethoxylated and propoxylated (alkyl) chains; alkylaryl sulfonates (C4-C 30 Alkyl, C4-C 30 aryl), or having C4-C 30 Alkyl, arylalkyl (C4-C 30 Alkyl, C4-C 30Mono- or di-substituted amides of propoxylated, ethoxylated, or ethoxylated and propoxylated (meth)acrylamide having a C4-C 30 Alkyl, arylalkyl (C4-C 30 Alkyl, C4-C 30 Aryl), or C4-C 30 Dialkyl chain propoxylated, ethoxylated or ethoxylated and propoxylated (meth)acrylamide derivatives; alkyl aryl sulfonates (C4-C 30 Alkyl, C4-C 30 aryl) and mixtures thereof.

[0077] The anionic water-soluble polymer advantageously comprises 1 mol % of at least one hydrophobic monomer C. The anionic water-soluble polymer may be free of hydrophobic monomers C.

[0078] When the anionic water-soluble polymers according to the invention comprise one or more hydrophobic monomers C, these are present in such an amount that the polymer remains water-soluble.

[0079] The amount of the different monomers will be adjusted by the person 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.

[0080] Structured system

[0081] The structuring system of anionic water-soluble polymers comprises:

[0082] (i) at least one compound I;

[0083] (ii) at least one compound II.

[0084] The compound I used in the context of the present invention is selected from the group consisting of allylsulfonic acid, methallylsulfonic acid, allyldisulfonic acid, methallyldisulfonic acid, salts thereof and mixtures thereof. Preferably, the compound I is methallylsulfonic acid, such as sodium methallylsulfonate.

[0085] The salified form advantageously corresponds to a salt of an alkali metal (Li, Na, K . . . ), an alkaline earth metal (Ca, Mg . . . ) or ammonium (eg ammonium ion or tertiary ammonium). The preferred salt is the sodium salt.

[0086] The anionic water-soluble polymer advantageously comprises from 500 to 50,000 ppm, preferably from 1000 to 20,000 ppm, more preferably from 2000 to 10,000 ppm of compound I relative to the total weight of monomers A and B (+ optional monomers C) of the anionic water-soluble polymer.

[0087] The compounds II used in the context of the present invention have the general formula:

[0088]

[0089] R1 and R2 are independently a hydrogen atom, a methyl group, an ethyl group, an isopropyl group or a CH2-OH group;

[0090] R1 and R2 are not both hydrogen atoms (when R2=H, R1≠H; when R1=H, R2≠H).

[0091] The compound II used in the context of the present invention is advantageously selected from the group consisting of N,N-dimethylacrylamide, N,N-diethylacrylamide, N,N-isopropylacrylamide, N-methylolacrylamide and mixtures thereof. Preferably, the compound II is N,N-dimethylacrylamide.

[0092] The anionic water-soluble polymer according to the invention advantageously comprises from 500 to 50,000 ppm, preferably from 1000 to 20,000 ppm, more preferably from 2000 to 10,000 ppm of compound II relative to the total weight of monomers A and B (+ optional monomers C) of the anionic water-soluble polymer.

[0093] In the anionic water-soluble polymer, the mass ratio of compound I to compound II is advantageously from 0.01 to 100, preferably from 0.1 to 10.

[0094] In a preferred embodiment according to the present invention, the amount of compound I is greater than the amount of compound II. Therefore, the mass ratio of compound I to compound II is advantageously greater than 1 and less than or equal to 100, preferably greater than 1 and less than or equal to 10.

[0095] Optional

[0096] The anionic water-soluble polymer may further comprise at least one crosslinking agent. The crosslinking agent may be selected from polyethylenically unsaturated monomers (having at least two unsaturated functional groups), such as vinyl functional groups, especially allyl groups, acrylic acid functional groups, or selected from monomers having at least two epoxy functional groups. The crosslinking agent may include, for example, methylenebisacrylamide (MBA), triallylamine, tetraallylammonium chloride, 1,2-dihydroxyethylenebis-(N-acrylamide) and mixtures thereof. Preferably, the crosslinking agent is methylenebisacrylamide (MBA).

[0097] The amount of crosslinker in the anionic water-soluble polymer is advantageously between 5 and 5000 ppm, more preferably between 50 and 3000 ppm, relative to the total weight of monomers A and B (+ optional monomers C) of the anionic water-soluble polymer.

[0098] In a particular embodiment according to the invention, the anionic water-soluble polymer does not comprise a crosslinking agent.

[0099] The anionic water-soluble polymer according to the invention may further comprise at least one transfer agent, for example chosen from methanol, isopropanol, sodium hypophosphite, 2-mercaptoethanol and mixtures thereof. We may also mention transfer agents of the xanthate, dithiocarbonate, dithiocarbamate and trithiocarbonate type and mixtures thereof. Preferably, the transfer agent is sodium hypophosphite.

[0100] The amount of transfer agent in the anionic water-soluble polymer is advantageously between 10 and 10,000 ppm, more preferably between 50 and 5000 ppm, relative to the total weight of monomers A and B (+ optional monomers C) of the anionic water-soluble polymer.

[0101] In a particular embodiment of the present invention, the anionic water-soluble polymer does not comprise a transfer agent.

[0102] Physical properties of water-soluble polymers

[0103] The weight average molecular weight of the water-soluble polymer is advantageously from 1,000,000 to 25,000,000 Daltons, preferably from 2,000,000 to 15,000,000 Daltons, more preferably from 3,000,000 to 10,000,000 Daltons. This is the weight average molecular weight.

[0104] The weight average molecular weight is preferably measured by gel permeation chromatography.

[0105] Anionic water-soluble polymers are obtained and used in liquid form.

[0106] The viscosity of the solution containing the anionic water-soluble polymer is advantageously 1000 to 50,000 cps, preferably 5000 to 20,000 cps.

[0107] Renewable sources

[0108] In a preferred embodiment according to the invention, the anionic water-soluble polymers are prepared from compounds (monomers and / or compounds I and II) which are at least partly of renewable, non-fossil origin.

[0109] In the context of the present invention, the term "renewable non-fossil origin" denotes a source of a compound derived from biomass or synthesis gas, i.e. the result of one or more chemical transformations of one or more raw materials of natural non-fossil origin. The terms "biosourced" or "bioresourced" may also be used to characterize a renewable non-fossil source of a compound. A renewable non-fossil source of a compound comprises renewable non-fossil raw materials that originate from a circular economy and which have previously been recovered one or more times in a process for the recovery of materials derived from biomass, for example from the depolymerization of polymers or the conversion of pyrolysis oils.

[0110] According to the present invention, "at least partly of renewable non-fossil origin" means that the carbon content of biogenic origin is preferably between 5% and 100% by weight, preferably at least 30%, more preferably at least 50%, even more preferably at least 70%, even more preferably at least 90%, relative to the total weight of carbon of the compound, and even more preferably it consists of 100% carbon of biogenic origin.

[0111] In the context of the present invention, standard ASTM D6866-21, method B, is used to characterize the biogenic nature of a compound and to determine the biogenic carbon content of said compound. This value is expressed as a weight percentage of biogenic carbon relative to the total weight of carbon in said compound.

[0112] gradient

[0113] The anionic water-soluble polymer according to the present invention is a gradient polymer.

[0114] A polymer with a gradient structure is a polymer comprising at least two monomers where the composition of the monomers changes gradually, unlike block polymers where the composition changes abruptly, or random polymers where the composition does not change continuously. In gradient polymers, intra-chain and inter-chain repulsions are smaller because the composition changes gradually over the length of the polymer chain.

[0115] The gradient can be formed by a spontaneous or forced gradient. Spontaneous gradient polymerization is due to differences in monomer reactivity. Forced gradient polymerization involves changing the composition of the introduced monomers throughout the polymerization process.

[0116] The forced process comprises (1) introducing a first portion of monomers into a reactor, (2) adding at least one additional portion of monomers, advantageously different from the first portion, and (3) polymerizing the monomers introduced into the reactor. The polymerization of the monomers begins upon introduction of the first portion.

[0117] Adding additional part monomer can occur in parallel with introducing the first part monomer into the reactor (therefore the introduction of part can start and end at the same time). Therefore, the part can have an addition curve with different flow rates, but has the same total addition duration. In fact, the addition flow of part can be continuous or discontinuous, and can be constant or inconstant in the whole adding process. Or, starting to feed the first monomer (first part) into the reactor can be before starting to add the second monomer part. Or, the first and second parts monomers can be introduced simultaneously, but the duration of adding the second part can be greater than the duration of introducing the first part into the reactor. This embodiment is also applicable to the method using at least 3 parts of monomers.

[0118] According to the process of the present invention, the anionic water-soluble polymer obtained is formed by stepwise addition of monomers, in other words, it is preferably a forced gradient method.

[0119] The method according to the invention comprises a first part (F1) and at least two additional parts (F2 and F3). At least one of the parts F1, F2 and F3 of the method is different from the other parts. Preferably, the parts F1, F2 and F3 are different from each other (F1≠F2≠F3). Different parts refer to parts with different monomers (ratios and / or properties of monomers) and / or compositions of compounds I and II (ratios and / or properties of compounds I and II).

[0120] Aggregation methods

[0121] The method for preparing anionic water-soluble polymers stepwise according to the present invention comprises the following steps:

[0122] a) forming a solution (S1) comprising at least one first part (F1) containing (1) at least one monomer selected from monomers A and B and (2) at least one compound selected from compounds I and II;

[0123] b) subjecting part F1 to polymerization 1 (PO1) so as to form a solution of a first gradient polymer (PG1);

[0124] c) adding a second part (F2) containing (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 comprising PG1;

[0125] d) polymerizing fraction F2 on PG1 (PO2) to form a solution of a second gradient polymer (PG2);

[0126] e) adding a third part (F3) containing (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 comprising PG2;

[0127] f) polymerizing part F3 on PG2 (PO3) to form a polymer comprising an anionic water-soluble polymer and

[0128] A solution of at least one of the parts F1, F2 or F3 containing at least one monomer A, at least one of the parts F1, F2 or F3 containing at least one monomer B, at least one of the parts F1, F2 or F3 containing at least one compound I and at least one of the parts F1, F2 or F3 containing at least one compound II.

[0129] The method may include the addition of additional portions.

[0130] The improved properties of the water-soluble anionic polymers according to the invention are probably due to the fact that the polymerization is carried out stepwise and continuously, ie without interruptions.

[0131] "Stepwise" means that the polymerization of the monomers of the anionic water-soluble polymer is carried out in multiple parts without being interrupted, that is, the addition of these parts is carried out continuously and the polymerization is not stopped. Therefore, the different steps a) to f) are carried out continuously. In other words, the first part of the monomers can be poured (in a flowing form) and polymerized to form a first gradient polymer PG1, which continues to polymerize with part F2 to form a gradient polymer PG2, which itself continues to polymerize with part F3 to obtain an anionic water-soluble polymer at the end of the polymerization.

[0132] Preferably, at least one of the fractions F1, F2 and F3 of the process is different from the other fractions. Preferably, the fractions F1, F2 and F3 are different from each other (F1≠F2≠F3). Adding different fractions during the polymerization process allows obtaining a gradient in the composition of the anionic water-soluble polymer.

[0133] In the polymerization process according to the 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.

[0134] Step a), forming a solution (S1) comprising a first part (F1)

[0135] Solution (S1)

[0136] Solution S1 advantageously consists of:

[0137] - solvent;

[0138] - initiator;

[0139] -Part I F1.

[0140] The solvent is advantageously water, or a solvent in which the monomers and the anionic water-soluble polymer are soluble. Preferably, the solvent is water.

[0141] The polymerization initiator used can be any compound that dissociates into free radicals under the polymerization conditions, for example: organic peroxides, hydroperoxides, hydrogen peroxide, persulfates, azo compounds and redox pairs. Preferably, water-soluble initiators are used. In some cases, it is advantageous to use a mixture of various polymerization initiators, for example a mixture of a redox catalyst and an azo compound. Preferably, the polymerization initiator is a persulfate.

[0142] In certain embodiments, solution S1 is formed by mixing solvent, initiator, and portion F1 in a polymerization vessel.

[0143] In this particular embodiment, part F1 can be added to the solvent / initiator mixture all at once, in portions or poured (in flowing form), ie gradually (eg dropwise). Preferably, part F1 is added all at once to the polymerization vessel.

[0144] In a particular embodiment of the invention, the initiator and part F1 are poured (in flowing form) into the polymerization vessel containing the solvent. The initiator and part F1 can be added separately or premixed. Preferably, the initiator and part F1 are added separately.

[0145] In a preferred embodiment of the invention, the initiator is added continuously throughout the process (steps a) to f)). In this case, the initiator is advantageously added in parallel with the different portions during the different polymerization steps and during the possible aging steps of the different gradient polymers (PG1 and PG2) and the anionic water-soluble polymer.

[0146] In this preferred embodiment of the invention, the pouring duration of the initiator is from 50 minutes to 560 minutes, preferably from 130 minutes to 430 minutes.

[0147] Part 1 (F1)

[0148] Advantageously, fraction F1 comprises from 10 to 40% by weight, preferably from 15 to 30% by weight, of monomers (A and / or B, + optional C) relative to the total weight of monomers of anionic water-soluble polymer (A+B+optionally C).

[0149] Fraction F1 advantageously comprises from 0 to 50 mol %, preferably from 0 to 35 mol %, of anionic monomers A relative to the total number of moles of monomers in fraction F1.

[0150] Fraction F1 advantageously comprises from 50 to 100 mol %, preferably from 65 to 100 mol %, of nonionic monomers B relative to the total moles of monomers in fraction F1.

[0151] Fraction F1 advantageously comprises from 250 to 30,000 ppm, preferably from 500 to 10,000 ppm and more preferably from 1000 to 7000 ppm of compound I relative to the total weight of monomers A and B (+ optional monomers C) of the anionic water-soluble polymer.

[0152] Fraction F1 advantageously comprises from 250 to 30,000 ppm, preferably from 500 to 10,000 ppm and more preferably from 1000 to 5000 ppm of compound II relative to the total weight of monomers A and B (+ optional monomers C) of the anionic water-soluble polymer.

[0153] The different monomers and compounds constituting part F1 are advantageously added in the form of solutions. These solutions can be added to the polymer container individually or in the form of a mixture, all at once, in multiple portions or poured (in a flowing form) to form solution S1. Preferably, they are added in the form of a mixture and all at once.

[0154] When pouring fraction F1 (in flowing form), this pouring advantageously lasts from 10 minutes to 80 minutes, preferably from 40 minutes to 70 minutes.

[0155] In a preferred embodiment, fraction F1 is prepared in a reactor (polymerization vessel) prior to the addition of the initiator.

[0156] In a preferred embodiment, fraction F1 contains at least one monomer B, at least one compound I and at least one compound II.

[0157] Step b), polymerizing fraction F1 to form a first gradient polymer (PG1)

[0158] Polymerization 1 (PO1)

[0159] Prior to polymerizing PO1, the atmosphere of the polymerization vessel may be replaced with an inert gas such as nitrogen or argon.

[0160] The polymerization PO1 is advantageously a free-radical polymerization. A polymerization initiator may be used, in particular an initiator which dissociates into free radicals under the polymerization conditions.

[0161] The polymerization PO1 is advantageously started at a temperature ranging from 70 to 90° C., preferably from 75 to 85° C. The polymerization temperature is advantageously controlled using cooling means so as not to exceed 95° C.

[0162] The polymerization PO1 advantageously lasts from 10 minutes to 80 minutes, preferably from 40 minutes to 70 minutes.

[0163] The polymerization advantageously starts when the first monomer, the solvent and the initiator are brought into contact. That is, the duration of the polymerization PO1 advantageously corresponds to the duration of the pouring of the fraction F1.

[0164] Gradient polymer (PG1)

[0165] At the end of the polymerization PO1, a gradient polymer (or prepolymer) PG1 is obtained.

[0166] In a particular embodiment according to the invention, the gradient polymer PG1 is allowed to age for 5 to 60 minutes, preferably 10 to 30 minutes.

[0167] "Allowing to age" means that after the end of the polymerization, the temperature of the solvent is kept between 80 and 90°C in order to allow the viscosity to increase by internal branching of the polymer. The definition of ageing relates to all steps of the polymerization process.

[0168] Step c), adding the second part (F2) to the solution containing PG1

[0169] Part 2 F2

[0170] Advantageously, fraction F2 comprises from 30 to 80% by weight, preferably from 40 to 70% by weight, of monomers (A and / or B, + optional C) relative to the total weight of monomers of anionic water-soluble polymer (A+B+optionally C).

[0171] Fraction F2 advantageously comprises from 0 to 70 mol %, preferably from 0 to 50 mol %, of anionic monomers A relative to the total moles of monomers in fraction F2.

[0172] Fraction F2 advantageously comprises from 30 to 100 mol %, preferably from 65 to 100 mol %, of nonionic monomers B relative to the total moles of monomers in fraction F2.

[0173] Fraction F2 advantageously comprises from 250 to 30,000 ppm, preferably from 500 to 10,000 ppm and more preferably from 1000 to 5000 ppm of compound I relative to the total weight of monomers A and B (+ optional monomers C) of the anionic water-soluble polymer.

[0174] Fraction F2 advantageously comprises from 250 to 30,000 ppm, preferably from 500 to 10,000 ppm and more preferably from 1000 to 5000 ppm of compound II relative to the total weight of monomers A and B (+ optional monomers C) of the anionic water-soluble polymer.

[0175] The different monomers and compounds constituting F2 are advantageously added in the form of a solution. The solution can be added to the polymer container all at once, in multiple portions or in a flowing form, either individually or in the form of a mixture. Preferably, the addition is carried out in a mixture and in a flowing form.

[0176] The pouring of fraction F2 advantageously lasts from 10 minutes to 100 minutes, preferably from 30 minutes to 90 minutes.

[0177] In a preferred embodiment, fraction F2 contains at least one monomer A and B, at least one compound I and at least one compound II.

[0178] Step d), polymerizing part F2 on PG1 to form a second gradient polymer (PG2)

[0179] Polymerization (PO2)

[0180] The polymerization PO2 is carried out as a continuation of the polymerization PO1; the polymerization PO2 is carried out under the same temperature conditions (advantageously between 70 and 90° C.).

[0181] The polymerization PO2 advantageously lasts from 10 to 100 minutes, preferably from 30 to 90 minutes.

[0182] Polymerization PO2 starts with the addition of the first monomer of fraction F2.

[0183] Advantageously, the duration of polymerizing PO2 corresponds to the duration of pouring of fraction F2.

[0184] Gradient Polymer (PG2)

[0185] At the end of the polymerization PO2, a gradient polymer (or prepolymer) PG2 is obtained.

[0186] In a particular embodiment according to the present invention, the gradient polymer PG2 is allowed to age for 5 to 60 min, preferably 10 to 30 min.

[0187] Step e), adding a third part (F3) to the solution containing PG2

[0188] Section F3

[0189] Advantageously, fraction F3 comprises from 5 to 40% by weight, preferably from 10 to 30% by weight, of monomers (A and / or B + optional C) relative to the total weight of monomers of anionic water-soluble polymer (A + B + optional C).

[0190] Fraction F3 advantageously comprises from 0 to 50 mol %, preferably from 0 to 35 mol %, of anionic monomers A relative to the total moles of monomers in fraction F3.

[0191] Fraction F3 advantageously comprises from 50 to 100 mol %, preferably from 65 to 100 mol %, of nonionic monomers B relative to the total moles of monomers in fraction F3.

[0192] Fraction F3 advantageously comprises from 0 to 10,000 ppm, preferably from 10 to 5000 ppm and more preferably from 20 to 1000 ppm of compound I relative to the total weight of monomers A and B (+ optional monomers C) of the anionic water-soluble polymer.

[0193] Fraction F3 advantageously comprises from 0 to 10,000 ppm, preferably from 0 to 1000 ppm, of compound II relative to the total weight of monomers A and B (+ optional monomers C) of the anionic water-soluble polymer.

[0194] The different monomers and compounds constituting F3 are advantageously added in the form of solutions. These solutions can be added to the polymer container all at once, in multiple portions or in a flowing form (i.e. dropwise), either individually or in the form of a mixture. Preferably, they are added in a mixture and in a flowing form.

[0195] The pouring of fraction F3 advantageously lasts from 10 minutes to 100 minutes, preferably from 30 minutes to 90 minutes.

[0196] In a preferred embodiment, part F3 contains at least one monomer B and at least one compound I. Step f), part F3 is polymerized on PG2 to form an anionic water-soluble polymer (PO3)

[0197] The polymerization of PO3 is carried out as a continuation of the polymerization of PO2; the polymerization of PO3 is carried out under the same conditions of time and temperature as PO2 (advantageously at 70 to 90° C. for 10 to 100 minutes, preferably 30 to 90 minutes).

[0198] Polymerization PO3 starts with the addition of the first monomer of fraction F3.

[0199] Advantageously, the duration of polymerizing PO3 corresponds to the duration of pouring of fraction F3.

[0200] At the end of the polymerization of PO3, an anionic water-soluble polymer is obtained.

[0201] In a particular embodiment according to the invention, the anionic water-soluble polymer is allowed to age for 5 to 60 minutes, preferably 10 to 30 minutes, before removing the residual monomers.

[0202] The reaction is advantageously terminated by adding an excess of initiator and / or water; this step serves to eliminate any residual monomers that may be present in the solution comprising the anionic water-soluble polymer.

[0203] One or more optional steps

[0204] The method according to the present invention may also include additional steps and is not limited to the above steps.

[0205] In a particular embodiment according to the invention, the polymerization process according to the invention may comprise the addition of additional moieties constituting the final anionic water-soluble polymer.

[0206] In a preferred embodiment according to the invention, after step f) of polymerizing PO3, the anionic water-soluble polymer is allowed to age for 10 to 100 minutes, preferably 30 to 90 minutes. In the case of adding an additional portion, the aging occurs after the last polymerization step.

[0207] In a particular embodiment according to the present invention, a crosslinking agent and / or a transfer agent is added during at least one of the above steps.

[0208] In a preferred embodiment according to the invention, a crosslinking agent is added to fraction F1 and / or fraction F2.

[0209] When a crosslinking agent is added, it is advantageously selected from the aforementioned crosslinking agents.

[0210] When a crosslinking agent is added, its amount is advantageously between 5 and 5000 ppm, preferably between 50 and 3000 ppm, relative to the total weight of the anionic water-soluble polymer (monomers A, B and optionally C).

[0211] In a preferred embodiment according to the invention, a transfer agent is added to part F1 and / or part F2.

[0212] When a transfer agent is added, it is advantageously selected from the aforementioned transfer agents.

[0213] When the transfer agent is added, its amount is advantageously between 10 and 10,000 ppm, preferably between 50 and 5000 ppm, relative to the total weight of the anionic water-soluble polymer (monomers A, B and optionally C).

[0214] Advantageously, the anionic water-soluble polymer obtained according to the process of the invention can be used without post-treatment other than salifying the polymer. The anionic water-soluble polymer can be used immediately after step f), or after one or more optional steps, in solution (without drying or prior purification), or after having been dried.

[0215] Papermaking method

[0216] The present invention also relates to a method for producing paper or paperboard, 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 the paper or paperboard. The present invention therefore relates to the use of anionic water-soluble polymers in a papermaking method.

[0217] The different steps of the process for producing paper, board or the like are known and according to the art utilizing the knowledge of a person skilled in the art; it is not necessary to describe these processes in more detail since, as far as the knowledge of a person skilled in the art is concerned, these processes are still known and conventional; if necessary, reference is made to the following document: Handbook for Pulp & Paper Technologists, 3rd edition, GASmook.

[0218] According to the invention, the anionic water-soluble polymer is added in the papermaking process before or after the formation of the paper, board or the like. Thus, the contacting of the cellulosic material with the polymer of the invention can be carried out in different ways, in particular according to conventional methods known to those skilled in the art.

[0219] The anionic water-soluble polymer may be added to the cellulosic material in the form of a diluted or undiluted aqueous solution.The anionic water-soluble polymer may be applied by an impregnation technique or may be added directly to the fiber suspension at any point in the papermaking process where dry strength agents are normally introduced.

[0220] Thus, the polymer according to the invention can be introduced into thick stock (English "thick stock") or diluted stock (English "thin stock"). The polymer according to the invention can be added at the mixing pump, before the headbox or the filter screen. Preferably, the polymer is introduced before the headbox.

[0221] Preferably, the polymer according to the invention is injected industrially into the fiber suspension, ie before it is diluted with pulp water (thick pulp).The consistency of the pulp is about 1-5% by weight of the cellulose fibers.

[0222] The papermaking process according to the invention can be used for any type of pulp, for example virgin fiber pulp (kraft, bisulfite), recycled fiber pulp, deinked pulp, mechanical pulp and thermomechanical pulp.

[0223] In a preferred embodiment according to the invention, anionic water-soluble polymers according to the invention are added together with cationic water-soluble polymers in order to enhance the dry strength properties of the paper while maintaining good drainage properties.

[0224] The cationic water-soluble polymer is advantageously selected from the following: PAE (polyaminopolyamide epichlorohydrin), polyvinylamine, glyoxylated polyacrylamide, PEI (polyethyleneimine), PA (polyamine, epichlorohydrin-dimethylamine resin), polymers obtained by Hofmann degradation, polyacrylamide, starch and mixtures thereof. Preferably, the cationic water-soluble polymer is a polymer obtained by Hofmann degradation.

[0225] Advantageously, the mass ratio of the anionic water-soluble polymer to the cationic water-soluble polymer of the present invention is 1 / 10 to 10 / 1.

[0226] Advantageously, the anionic water-soluble polymer and the cationic water-soluble polymer are added directly to the fiber suspension prior to sheet formation.

[0227] The anionic water-soluble polymer and the cationic water-soluble polymer may be added individually or in a mixture, in any order of introduction, at a single injection point or at two injection points.

[0228] As required, the papermaking method according to the present invention may also include the addition of other additives and / or polymers; as non-limiting examples, mention may be made of: biocides, coagulants, cross-linking agents, flocculants, starches, etc.

[0229] use

[0230] The invention also relates to the use of anionic water-soluble polymers in the recovery of hydrocarbons (oil and / or gas); in drilling or cementing wells; in the stimulation of hydrocarbon wells (oil and / or gas), for example hydraulic fracturing, conformance, diversion; in the treatment of water in open, closed or semi-closed cycles; in the treatment of fermentation mash, in the treatment of sewage sludge; in construction; in wood treatment; in the treatment of hydraulic compositions (concrete, cement, mortar and aggregates); in the mining industry; in the formulation of cosmetics; in the battery field; in the formulation of detergents; in textile production; in geothermal technology; in diaper production; or in agriculture.

[0231] The invention also relates to the use of anionic water-soluble polymers as flocculants, coagulants, adhesives, fixatives, viscosity reducers, thickeners, absorbents, friction reducers, drainage agents, filler retainers, dehydrating agents, conditioners, stabilizers, fixatives, film formers, sizing agents, superplasticizers, clay inhibitors or dispersants.

[0232] The invention and its advantages will become more apparent in the following examples given in order to illustrate the invention in a non-limiting manner.

[0233] Example

[0234] List of abbreviations:

[0235] AMD: Acrylamide (Monomer B)

[0236] AA: Acrylic acid (monomer A)

[0237] DMAM: dimethylacrylamide (compound II)

[0238] SMS: Sodium methyl allyl sulfonate (Compound I)

[0239] SPS: Sodium persulfate (polymerization initiator)

[0240] ATBS: 2-Acrylamido-2-methylpropanesulfonic acid (monomer A)

[0241] IA: Itaconic acid (monomer A)

[0242] DMAEMA: dimethylaminoethyl methacrylate (cationic polymer)

[0243] Description of GPC-Malls Characterization of Molecular Weight

[0244] Gel permeation chromatography is a method that makes it possible to separate macromolecules as a function of their hydrodynamic volumes; gel permeation chromatography is coupled to a Malls detector that makes it possible to measure the scattering of light from multiple angles.

[0245] The synthesized polymers were analyzed under the following conditions:

[0246] -Instrument: GPC-2

[0247] - Column: Shodex SB-807-HQ and SB-805 customized

[0248] -method:

[0249] * Temperature: 30℃

[0250] * Mobile phase: 0.5M NaNO3, HEPES (pH=8), 100ppm NaN3

[0251] * Injection: 100 μL

[0252] * Flow rate: 0.3mL / min

[0253] * Detection:

[0254] (i) Light scattering detector (MALS): absolute molar mass

[0255] (ii) Refractometry (RI): Concentration

[0256] The viscosity was measured using a Brookfield viscometer with a Brookfield LV3 module at 25°C and a speed of 6 rpm.

[0257] Preparation of polymers 1-5 (P1-P5(INV)) according to the invention

[0258] Polymer 1 (P1)

[0259] Step 1: Gradient polymer or prepolymer PG1

[0260] In a 1-liter reactor equipped with a mechanical stirrer, a thermometer, a condenser and a rod impregnated with gaseous nitrogen, a first part F1 consisting of 165.6 g of water, 71.2 g of acrylamide (50% by weight in water), 1 g of citric acid, 0.5 g of dimethylacrylamide and 0.68 g of sodium methallyl sulfonate is introduced as a starter. The medium is heated and maintained at a temperature of 79-81° C. by means of a water bath. The addition of 0.05 g of sodium persulfate makes it possible to initiate the starter and initiate the polymerization of the monomer (PO1) so as to form a first gradient polymer PG1.

[0261] Step 2: Gradient polymer or prepolymer PG2

[0262] When the exothermic reaction was over, flow was started: initiator (30 g SPS, 0.33 wt % solution in water) for 130 minutes, while the second part F2, consisting of 28.8 g water, 124.9 g acrylamide (50 wt % solution in water), 23 g acrylic acid 100%, 0.5 g dimethylacrylamide and 0.33 g sodium methacrylate sulfonate, was continued for 50 minutes. After pouring part F2, the gradient polymer PG2 was allowed to age for 10 minutes (polymerization PO2 for forming the gradient polymer PG2 was carried out during pouring part F2 and during the aging period).

[0263] Step 3: Polymer 1 (P1)

[0264] Then, a third portion F3 consisting of 136.8 g of water, 61.1 g of acrylamide (50 wt % aqueous solution), 0.01 g of sodium methyl allyl sulfonate was flowed for more than 60 minutes. At the end of the addition of portion F3, the polymer was allowed to age for 10 minutes (polymerization PO3 for forming the polymer was carried out during the pouring and aging of portion F3). Once aging was completed, 165.3 g of water and 0.15 g of sodium persulfate were added. When the desired viscosity was reached, the reaction was stopped by adding 2.4 g of sodium bisulfite (40 wt % aqueous solution) and 165.2 g of water. Aging was continued for another 60 minutes before cooling. The solution containing polymer 1 (P1) had a pH of 3.5, 15 wt % active matter, a viscosity of 8900 cps, and a molecular weight of 4,580,000 Da obtained by GPC-Malls.

[0265] Polymers 2 to 5 according to the invention (P2 to P5 (INV))

[0266] The protocol for the preparation of polymer 1 (P1) was replicated while varying the composition of the different parts in order to produce polymers 2-5 (P2-P5); the compositions of the different parts used to obtain these polymers are summarized in Table 1.

[0267] Preparation of Counter-Example Polymers 6 to 11 (CE1 to CE6)

[0268] Polymer 6 (CE1)

[0269] The polymer is prepared in one step.

[0270] In a 1 liter reactor equipped with a mechanical stirrer, a thermometer, a condenser and a gaseous nitrogen impregnated rod, 663.7 g of water, 262.9 g of acrylamide (50% by weight in water), 23.5 g of acrylic acid 100%, 0.5 g of dimethylacrylamide and 0.65 g of sodium methallyl sulfonate were introduced. The pH was adjusted to 6 by adding 23 g of NaOH (50% by weight in water). The reactor was heated to 35° C. The reaction was initiated by adding 0.16 g of VA 044.

[0271] When the maximum temperature was reached, aging was allowed for 60 minutes before adding 2.4 g of sodium bisulfite (40 wt% aqueous solution). Aging was allowed for an additional 60 minutes before cooling. The solution containing Counter Example Polymer 6 (CE1) had a pH of 7, 15 wt% active matter, a viscosity of 7000 cps, and a molecular weight of 1,400,000 Da obtained by GPC-Malls.

[0272] Polymer 7 (CE2)

[0273] Polymer 7 was prepared according to the same protocol as Polymer 6 while varying the monomer composition of the polymer.

[0274] Polymer 8 (CE3)

[0275] Polymer 8 was prepared according to the same protocol as polymer 1 (ie 3 steps), except that this polymer was obtained in the absence of compound II (DMAM).

[0276] Polymer 9 (CE4)

[0277] Polymer 9 (CE4) was prepared according to the same protocol as polymer 1 (ie 3 steps), except that it was obtained in the absence of compound I (SMS) and compound II (DMAM) but in the presence of the transfer agent sodium hypophosphite (Hypo).

[0278] Polymer 10 (CE5)

[0279] Polymer 10 (CE5) was prepared according to the same protocol as polymer 1, but with only 2 steps.

[0280] Polymer 11 (CE6)

[0281] Polymer 11 (CE6) was prepared according to the same protocol as polymer 1 (ie 3 steps) while varying the monomer composition of the polymer to obtain an amphoteric polymer.

[0282] The compositions of the different parts of the preparation process of polymers 1-11 are summarized in Table 1a.

[0283] In Table 1a, the monomer content represents the molar weight percentage of AMD (or AA or ATBS or IA) monomer relative to the total molar weight of the corresponding monomer in the total fraction. Thus, for example, the sum of the percentages of AMD monomer in the three fractions equals 100%.

[0284] The contents of compound I (SMS) and compound II (DMAM) are expressed in ppm by weight relative to the total weight of the monomer or monomers in the three parts.

[0285] [Table 1a]

[0286]

[0287]

[0288]

[0289] Table 1a: Composition of one or more parts of the polymerization process from which polymers P1 to P5 and counterexamples P6 to P11 (CE1 to CE6) were obtained.

[0290] The physicochemical properties of the obtained polymer are described in Table 1b below:

[0291] [Table 1b]

[0292]

[0293]

[0294] Table 1 b: Physicochemical properties of polymers P1 to P5 according to the invention and counterexamples CE1 to CE6.

[0295] Table 2 summarizes the compositions of the different parts (monomers A and B, compounds I and II) for the preparation of polymers P1 to P5 (INV) and CE1 to CE6.

[0296]

[0297] Table 2: Composition of the various parts in the synthesis of polymers 1-9.

[0298] Application Testing

[0299] Polymers 1 to 11 are used in combination with the following cationic polymers:

[0300] HF 31: polymer of SNF wire, polyvinylamine obtained by Hofmann degradation, cationic, having a viscosity of 200 cps and a dry extract of 21 wt%.

[0301] VP 450: polymer of SNF wire, polyvinylamine obtained by hydrolysis of polyvinylformamide, cationic, having a viscosity of 1380 cps and a dry extract of 19.2 wt%.

[0302] The drainage and dry strength properties of polymers 1-11 in combination with HF 31 and VP 450 were evaluated according to the following conditions.

[0303] The wet pulp used in all application examples was obtained by disintegrating dry pulp so as to obtain a final water concentration of 1 wt. %. The wet pulp was a neutral pH pulp consisting of 100 % recycled paperboard fibers.

[0304] Drainage Vacuum Assessment (DDA)

[0305] The DDA ("Dynamic Drainage Analyzer") automatically determines the time (in seconds) required to vacuum drain the fiber suspension from the fabric. The polymer was added to the wet pulp (0.6 liters of pulp, 1.0 wt. %) in the drum of the DDA under stirring at 1000 rpm:

[0306] T=0s:Stirring pulp

[0307] T = 10s: Add one or more polymers

[0308] T = 30s: Stop stirring and drain under vacuum at 200 mbar for 60s

[0309] The pressure under the fabric is recorded as a function of time. When all the water has been removed from the fiber mat, air passes through the mat, causing a sudden change in the slope of the curve representing the pressure under the fabric as a function of time. The time, expressed in seconds, is recorded at this sudden change in slope, which corresponds to the draining time. The shorter the time, the better the vacuum draining.

[0310] Performance in dry strength applications, 80g.m -2

[0311] Collect the necessary amount of pulp to obtain a final weight of 80 g.m. -2 of paper.

[0312] The wet pulp is introduced into the barrel of the dynamic paper forming machine and kept stirred. The different parts of the system are injected into the pulp according to the preset sequence. Generally speaking, a contact time of 30-45 seconds should be maintained between each addition of polymer.

[0313] The paper forming is realized by an automatic dynamic paper forming machine: the absorbent paper and forming fabric are placed in the drum of the dynamic paper forming machine before the drum starts to rotate at 1000rpm and forms a water wall. The treated pulp is distributed on the water wall to form a fiber mat on the forming fabric.

[0314] Once the water was drained, the fiber mat was recovered, pressed at a pressure of 4 bars and then dried at 117° C. The paper obtained was conditioned overnight in a room with controlled humidity and temperature (50% relative humidity and 23° C.). The dry strength properties of all the papers obtained by this procedure were then measured.

[0315] The burst properties were measured with a Messmer Buchel M 405 burst tester according to standard TAPPI T403 om-02.

[0316] The dry breaking length was measured in the machine direction using a Testometric AX pulling device according to standard TAPPI T494 om-01.

[0317]

[0318]

[0319] Table 3: Drainage and dry strength results for compositions comprising cationic polymer HF 31 or VP 450 with polymers 1 to 5 according to the invention (INV) and with comparative polymers 6 to 11 (CE)

[0320] Interestingly, it is noted that the polymers of the invention (1 to 5) in combination with cationic polymers have improved drainage properties (DDA) and mechanical properties (burst resistance: burst resistance; DBL: dry break) compared to polymers prepared by conventional methods (polymers 6 and 7), in the absence of a structuring system (polymers 8 and 9), in the absence of a third part (polymer 10) or in the presence of a cationic monomer (polymer 11).

Claims

1. An anionic water-soluble polymer comprising: - at least one anionic monomer A; - at least one nonionic monomer B; - At least one structured system comprising: (i) at least one compound I which is different from at least one monomer A and is selected from the group consisting of allylsulfonic acid, methallylsulfonic acid, allyldisulfonic acid, methallyldisulfonic acid, salts thereof and mixtures thereof; (ii) at least one compound II of the formula II which is different from at least one monomer B: R1 and R2 are independently a hydrogen atom, a methyl group, an ethyl group, an isopropyl group or a CH2-OH group; R1 and R2 are not both hydrogen atoms, The polymer is free of cationic monomers and zwitterionic monomers; The anionic water-soluble polymer is obtained according to the following steps: a) forming a solution (S1) comprising a first part (F1) containing (1) at least one monomer selected from monomers A and B and (2) at least one compound selected from compounds I and II; b) subjecting part F1 to polymerization 1 (PO1) so as to form a solution of a first gradient polymer (PG1); c) adding a second part (F2) containing (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 comprising PG1; d) polymerizing part F2 on PG1 (PO2) to form a solution of a second gradient polymer (PG2); e) adding a third part (F3) containing (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 comprising PG2; f) polymerizing part F3 on PG2 3 (PO3) so as to form a solution comprising an anionic water-soluble polymer and at least one of parts F1, F2 or F3 contains at least one monomer A, at least one of parts F1, F2 or F3 contains at least one monomer B, at least one of parts F1, F2 or F3 contains at least one compound I, and at least one of parts F1, F2 or F3 contains at least one compound II.

2. The anionic water-soluble polymer according to claim 1, characterized in that The at least one anionic monomer A is selected from the following: acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, acrylamidoundecanoic acid, 3-acrylamido-3-methylbutyric 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. The anionic water-soluble polymer according to claim 1 or 2, characterized in that The at least one nonionic monomer B is selected from the following: 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; the alkyl group is C1-C3.

4. Anionic water-soluble polymer according to any one of the preceding claims, characterized in that The anionic water-soluble polymer contains 500 to 50,000 ppm of compound I relative to the total weight of monomers A and B.

5. Anionic water-soluble polymer according to any one of the preceding claims, characterized in that The anionic water-soluble polymer contains 500 to 50,000 ppm of the compound II relative to the total weight of monomers A and B.

6. Anionic water-soluble polymer according to any one of the preceding claims, characterized in that The compound II is selected from the group consisting of N,N-dimethylacrylamide, N,N-diethylacrylamide, N,N-isopropylacrylamide, N-hydroxymethylacrylamide and mixtures thereof.

7. Anionic water-soluble polymer according to any one of the preceding claims, characterized in that The mass ratio of compound I to compound II is 0.01 to 100.

8. A method for gradually preparing anionic water-soluble polymers, comprising: - at least one anionic monomer A; - at least one nonionic monomer B; - At least one structured system comprising: (i) at least one compound I which is different from at least one monomer A and is selected from the group consisting of allylsulfonic acid, methallylsulfonic acid, allyldisulfonic acid, methallyldisulfonic acid, salts thereof and mixtures thereof; (ii) at least one compound II of the formula II which is different from at least one monomer B: R1 and R2 are independently a hydrogen atom, a methyl group, an ethyl group, an isopropyl group or a CH2-OH group; R1 and R2 are not both hydrogen atoms (when R2=H, R1≠H; when R1=H, R2≠H); The polymer does not contain cationic monomers and zwitterionic monomers; The method comprises the following steps: a) forming a solution (S1) comprising at least a first part (F1) containing (1) at least one monomer selected from monomers A and B and (2) at least one compound selected from compounds I and II; b) subjecting part F1 to polymerization 1 (PO1) so as to form a solution of a first gradient polymer (PG1); c) adding a second part (F2) to the solution comprising PG1, wherein the second part (F2) contains (1) at least one monomer selected from monomers A and B and (2) at least one compound selected from compounds I and II; d) polymerizing fraction F2 on PG1 (PO2) to form a solution of a second gradient polymer (PG2); e) adding a third part (F3) to the solution comprising PG2, the third part (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; f) polymerizing part F3 on PG2 (PO3) so as to form a solution comprising an anionic water-soluble polymer and at least one of parts F1, F2 or F3 contains at least one monomer A, at least one of parts F1, F2 or F3 contains at least one monomer B, at least one of parts F1, F2 or F3 contains at least one compound I, and at least one of parts F1, F2 or F3 contains at least one compound II.

9. The method according to claim 8, characterized in that The initiator was added continuously throughout the process.

10. The method according to claim 8 or 9, characterized in that: After step f) of polymerisation (PO3), the process comprises an ageing step of 10 to 100 minutes.

11. A method for producing paperboard, which comprises adding the anionic water-soluble polymer according to any one of claims 1 to 7 to an aqueous suspension of fibers and forming paper or paperboard.

12. Use of anionic water-soluble polymers according to any one of claims 1 to 7 in the recovery of hydrocarbons; in drilling or cementing; in the stimulation of hydrocarbon wells; in water treatment in open, closed or semi-closed cycles; in the treatment of fermentation mash, in the treatment of sewage sludge; in construction; in wood treatment; in the treatment of hydraulic compositions; in the mining industry; in the formulation of cosmetics; in the battery field; in the formulation of detergents; in textile production; in geothermal technology; in diaper production; or in agriculture.

13. Use of an anionic water-soluble polymer according to any one of claims 1 to 7 as a flocculant, coagulant, adhesive, fixative, viscosity reducer, thickener, absorbent, friction reducer, drainage agent, filler retention agent, dehydrating agent, conditioner, stabilizer, fixative, film former, sizing agent, superplasticizer, clay inhibitor or dispersant.

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