Novel polymer and preparation method thereof

Abstract

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

Description

Technical Field

[0001] The invention relates to a novel polyvinylamine polymer, a preparation method and application thereof, in particular to application in the field of papermaking. Background Art

[0002] The paper industry is constantly seeking to improve its methods of manufacturing paper, paperboard or the like, particularly with regard to cost reduction, yield, productivity and even the properties of the final product.

[0003] Water-soluble polyamines resulting from Hofman degradation are known and widely used in papermaking processes, in particular for improving drainage during sheet formation and for improving their resistance to drying. These polymers offer better application properties, but they also make it possible to increase paper machine speeds, thereby increasing productivity.

[0004] Hofman degradation is a reaction discovered by Hofman at the end of the 19th century which allows a functional group (eg, an amide) to be converted into a primary amine functional group having one less carbon atom. The reaction mechanism is described in detail below.

[0005] In the presence of a base (such as soda), a proton is removed from the amide.

[0006]

[0007] The resulting amide then reacts with the active chlorine (Cl2) of the hypochlorite (e.g. NaClO in equilibrium: ) to form N-chloramide. The base (NaOH) removes a proton from the chloramide to form an anion. The anion loses the chloride ion to form a nitrene, which is converted to an isocyanate.

[0008]

[0009] By the reaction between hydroxide ions and isocyanates, carbamates are formed.

[0010]

[0011] Decarboxylation of the carbamate (removal of CO2) affords the primary amine.

[0012]

[0013] For the conversion of all or part of the amide functionality of a polymer comprising amide groups as amine functionality, two main coefficients (expressed as molar ratios) are involved. These coefficients are:

[0014] - Coefficient α = hypohalite (alkali metal hypohalite and / or alkaline earth metal hypohalite)

[0015] / amide functionality (and, if applicable, nitrile);

[0016] - Factor β=hydroxide (alkali metal hydroxide and / or alkaline earth metal hydroxide) / hypohalite (alkali metal hypohalite and / or alkaline earth metal hypohalite).

[0017] Although Hofman degradation was originally directed to amide groups, it can also be applied to nitrile functional groups (-C≡N), specifically the nitrile functional groups of acrylonitrile polymers.

[0018] In general, the effectiveness of Hofman degradable polymers as dry strength agents increases with their cationicity. That is, the polymers used must be highly degradable in order to increase their cationicity. In fact, depending on the degree of degradation, different cationicities can be produced, which are related to the number of amine functional groups generated on the carbon skeleton of the polymer.

[0019] The cationicity of the degraded polymer may be caused by the formation of protonatable amine groups, but may also be caused by the possible presence of cationic monomers.

[0020] Until recently, only heavy processes were developed using in situ Hofmann degradation product production units (EP 377313), or processes using another polymer (N-vinylformamide polymer base followed by hydrolysis) (US 2004 / 118540) (which are also very expensive).

[0021] The first feasible industrial solution was proposed in the applicant's document WO2006075115 at the beginning of 2005. In this article, the Hofman degradation products described are organic polymers generated in concentrations greater than 3.5% by weight. Although the polymers described in this article can significantly improve dry strength properties, they have very low molecular weights, making their impact on applications such as drainage or flocculation very limited.

[0022] Documents WO 2008 / 107620 and WO / 2010 / 061082 of the applicant make it possible to partially solve the problem of poor drainage performance. However, the polymers described in these documents show a certain levelling-off performance in terms of drainage and retention.

[0023] Document WO 2009 / 013423 of the applicant also makes it possible to improve the drainage properties by proposing a post-treatment of the polymers produced by the Hofman reaction. This post-treatment consists in post-branching the copolymers obtained by Hofman degradation in the presence of at least one polyfunctional branching agent. However, this method has serious limitations, with a highly complex post-branching control (difficult to industrialize) and saturation properties at dosages greater than 1.5 kg of active matter per ton of paper.

[0024] Document WO 2011 / 015783 of the applicant proposes novel polymers making it possible to push back the saturation performance, in particular for high strengths, to about 2 kg of active matter / ton.

[0025] Document US Pat. No. 10,730,989 relates to a method for preparing an additive for papermaking based on a (meth)acrylamide copolymer.

[0026] Despite all these improvements, there are still persistent problems associated with Hofman degradation. The dual treatment, alkaline followed by acidic, together with the temperature, leads to a significant decrease in the viscosity of the base polymer. The polymers obtained in this way exhibit reduced application properties.

[0027] The Applicant has surprisingly found that the synthesis of polymers according to the process of the invention makes it possible to increase the molecular weight of the base polymer without affecting its viscosity. It appears that this increase in the molecular weight of the base polymer provides the paper with improved application properties in terms of dry strength, while also improving drainage, thus enabling an increase in paper machine speed and thus productivity, compared to existing solutions of the prior art.

[0028] The use of the polymers obtained by the invention is part of the general principle of improved product properties, more specifically dry strength and drainage properties. The improved properties of the polymers according to the invention make it possible to reduce the amount of product required for an application, which therefore involves reducing greenhouse gas emissions, such as CO2, associated with the manufacture and use of synthetic polymers. In addition, the improvement in drainage reduces the amount of energy required. Summary of the invention

[0029] The present invention relates to a polyvinylamine polymer obtained by subjecting a base polymer to a Hofman degradation reaction, the polyvinylamine polymer comprising:

[0030] - at least one cationic monomer A;

[0031] - at least one nonionic monomer B selected from acrylamide, acrylonitrile, methacrylamide and mixtures thereof;

[0032] - At least one structured system comprising:

[0033] At least one compound I selected from the group consisting of allyl sulfonic acid, methallyl sulfonic acid, allyl disulfonic acid, methallyl disulfonic acid, their salts and mixtures thereof;

[0034] At least one compound II of formula (1):

[0035]

[0036] R1 and R2 are independently a hydrogen atom, a methyl group, an ethyl group, an isopropyl group or a CH2-OH group;

[0037] R1 and R2 are not both hydrogen atoms (when R2=H, R1≠H; when R1=H, R2≠H)

[0038] - Optionally, at least one monomer C: a nonionic monomer, which is different from monomer B and from compound II; a zwitterionic monomer or a hydrophobic monomer;

[0039] - Optionally, at least one cross-linking agent;

[0040] - Optionally, at least one transfer agent.

[0041] The polyvinylamine polymer is obtained according to the following steps:

[0042] 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;

[0043] b) subjecting part F1 to polymerization 1 (PO1) to form a solution of a first gradient polymer (PG1);

[0044] 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;

[0045] d) polymerizing part F2 on PG1 (PO2) to form a solution of a second gradient polymer (PG2);

[0046] 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;

[0047] f) polymerizing part F3 on PG2 (PO3) to form a solution comprising the base polymer;

[0048] g) diluting the solution containing the base polymer and subjecting the base polymer to a Hofman degradation reaction to obtain a polyvinylamine polymer, and

[0049] at least one of the fractions F1, F2 or F3 contains at least one monomer A,

[0050] at least one of the fractions F1, F2 or F3 contains at least one monomer B,

[0051] At least one of the fractions F1, F2 or F3 contains at least one compound I, and

[0052] At least one of the fractions F1, F2 or F3 contains at least one compound II.

[0053] The polymer contains no anionic monomers other than compound I.

[0054] The invention also relates to a preparation method of the polyvinylamine polymer.

[0055] The present invention also relates to a method for making paper or paperboard using the polyvinylamine polymer.

[0056] The invention also relates to the use of the polyvinylamine polymer in the recovery of hydrocarbons (oil and / or gas); in drilling or cementing wells (especially hydrocarbon wells); in the stimulation of hydrocarbon wells (oil and / or gas), for example, in 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 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 formulation of detergents; in textile manufacture; in the geothermal field; in the manufacture of sanitary napkins; or in agriculture.

[0057] The invention also relates to the use of the polymers according to the invention as flocculants, coagulants, adhesives, fixatives, viscosity reducers, thickeners, absorbents, friction reducers, drainage agents, charge retention agents, dehydrating agents, conditioners, stabilizers, fixatives, film formers, sizing agents, superplasticizers, clay inhibitors or dispersants. DETAILED DESCRIPTION

[0058] "Polymer" is used to denote a copolymer prepared using at least two different monomers, having at least one cationic monomer A and at least one nonionic monomer B, and a structuring system comprising at least one compound I and at least one compound II; the "polymer" may optionally contain at least one zwitterionic hydrophilic monomer and / or one hydrophobic monomer and / or a crosslinker and / or a transfer agent.

[0059] In the context of the present invention, the base polymer and the polyvinylamine polymer obtained after Hofman degradation of the base polymer are water-soluble polymers.

[0060] A water-soluble polymer is a polymer that dissolves in deionized water at 25°C (10 g / L -1 ), a polymer in the form of an aqueous solution containing no insoluble particles can be obtained.

[0061] In the present invention, the first gradient polymer of step b) and the second gradient polymer of step d) are prepolymers.

[0062] Throughout the specification, viscosity is measured in aqueous solution at 25°C using a Brookfield viscometer.

[0063] In this specification, it is considered that a person skilled in the art is able to determine the Brookfield viscometer module and speed suitable for the viscosity range to be measured. In fact, this type of measurement is part of the common knowledge of a person skilled in the art.

[0064] "X and / or Y" means "X", or "Y", or "X and Y".

[0065] All possible combinations between the disclosed different embodiments, whether these are preferred embodiments or given as examples, are part of the present invention. In addition, when numerical ranges are given, the endpoint values ​​are included in these ranges. The present disclosure also includes all combinations between the endpoint values ​​and these numerical ranges. For example, the numerical range "1-20, preferably 5-15" includes the content of "1-5", "1-15", "5-20" and "15-20", as well as the numerical values ​​1, 5, 15 and 20.

[0066] In the present specification, the base polymer means the water-soluble polymer obtained according to the process of the present invention before it is subjected to the Hofman degradation reaction according to step g).

[0067] Base polymer

[0068] The present invention relates to polyvinylamine polymers produced by Hofman degradation of a base polymer and is characterized by a process for obtaining it.

[0069] The base polymer according to the present invention comprises:

[0070] - at least one cationic monomer A;

[0071] - at least one nonionic monomer B selected from acrylamide, acrylonitrile, methacrylamide and mixtures thereof;

[0072] - At least one structured system comprising:

[0073] (i) at least one compound I, which is different from at least one monomer A, and which is selected from the group consisting of allylsulfonic acid, methallylsulfonic acid, allyldisulfonic acid, methallyldisulfonic acid, their salts and mixtures thereof;

[0074] (ii) at least one compound II of formula (1):

[0075]

[0076] R1 and R2 are independently a hydrogen atom, a methyl group, an ethyl group, an isopropyl group or a CH2-OH group;

[0077] R1 and R2 are not both hydrogen atoms (when R2=H, R1≠H; when R1=H, R2≠H).

[0078] The base polymer contains no anionic monomers other than compound I.

[0079] Monomer composition

[0080] Monomer A

[0081] The base polymers according to the invention are synthetic polymers.

[0082] It may comprise one or more cationic monomers (referred to as "monomer(s) A").

[0083] Advantageously, the one or more cationic monomers A may be chosen in particular from vinyl monomers, in particular acrylamide, acrylic acid, allyl or maleic acid monomers with ammonium functional groups (advantageously quaternary ammonium). In particular, but not limited to, we can mention: diallyldimethylammonium chloride (DADMAC), acrylamidopropyltrimethylammonium chloride (APTAC) and methacrylamidopropyltrimethylammonium chloride (MAPTAC) and mixtures thereof. The preferred monomer is diallyldimethylammonium chloride (DADMAC).

[0084] The base polymer advantageously comprises from 1 to 60 mol %, preferably from 2 to 50 mol %, more preferably from 3 to 40 mol %, more preferably from 4 to 30 mol % of one or more cationic monomers A.

[0085] In a preferred embodiment, the base polymer comprises at least 30 mol % of one or more cationic monomers A.

[0086] Those skilled in the art know how to prepare quaternized monomers, for example by means of alkyl halides of the type RX, R being an alkyl group and X being a halogen group, (particularly methyl chloride). In addition, the invention also includes monomers of the type DADMAC, APTAC and MAPTAC, whose counter-ion halide is a fluoride, bromide or iodide instead of a chloride.

[0087] Monomer B

[0088] The base polymer comprises one or more nonionic monomers (referred to as "monomer(s) B").

[0089] As already indicated, the nonionic monomer B is selected from acrylamide, acrylonitrile, methacrylamide and mixtures thereof.

[0090] The base polymer advantageously comprises from 40 to 99 mol %, preferably from 50 to 98 mol %, more preferably from 60 to 97 mol % and even more preferably from 70 to 96 mol % of nonionic monomers B.

[0091] Monomer C

[0092] The base polymer may optionally comprise one or more monomers selected from the group consisting of nonionic monomers, zwitterionic monomers, hydrophobic monomers, and mixtures thereof (referred to as "monomers C") different from monomer B and different from compound II.

[0093] Advantageously, when monomer C is a nonionic monomer, it can be selected in particular from the group comprising water-soluble vinyl monomers. Preferred monomers belonging to this category are, for example, N-vinylpyrrolidone (NVP), N-vinylimidazole, N-vinylsuccinimide, acryloylmorpholine (ACMO), glycidyl methacrylate, glyceryl methacrylate, diacetone acrylamide, N-vinylformamide, N-vinyl-N-methylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide, N-vinyl-N-ethylacetamide, N-vinylpropionamide, N-vinyl-N-methylpropionamide, N-vinylbutanamide, hydroxyalkyl (meth)acrylates (C1-C3 alkyl), thioalkyl (meth)acrylates (C1-C3 alkyl) and mixtures thereof. The preferred monomer is N-vinylformamide.

[0094] The base polymer of the invention advantageously comprises from 0 to 40 mol %, preferably from 0 to 30 mol %, of nonionic monomers C (which are different from monomers B and compound II).

[0095] Advantageously, the zwitterionic monomers that can be used in the context of the present invention are chosen in particular from derivatives of the vinyl form, in particular derivatives of acrylamide, acrylic acid, allyl or maleic acid. Preferably, the monomers comprise an amine or quaternary ammonium functional group and a carboxylic acid (or carboxylate) type functional group, a sulfonic acid (or sulfonate) type functional group or a phosphoric acid (or phosphate) type functional group. The one or more zwitterionic monomers may be selected from: derivatives of dimethylaminoethyl acrylate, for example, 2-((2-(acryloyloxy)ethyl)dimethylammonium)ethane-1-sulfonate, specific mention may be made of, but not limited to, 3-((2-(acryloyloxy)ethyl)dimethylammonium)propane-1-sulfonate, 4-((2-(acryloyloxy)ethyl)dimethylammonium)butane-1-sulfonate, [2-(acryloyloxy)ethyl](dimethylammonium)acetate, derivatives of dimethylaminoethyl methacrylate, for example, 2-((2-(methacryloyloxy)ethyl)dimethylammonium)ethane-1-sulfonate, 3-((2-(methacryloyloxy)ethyl)dimethylammonium)propane-1-sulfonate, 4-((2-(methacryloyloxy)ethyl)dimethylammonium)butane-1-sulfonate, [2-(acryloyloxy)ethyl](dimethylammonium)acetate. esters, derivatives of dimethylaminoethylpropyl acrylamide, such as 2-((3-acrylamidopropyl)dimethylammonium)ethane-1-sulfonate, 3-((3-acrylamidopropyl)dimethylammonium)propane-1-sulfonate, 4-((3-acrylamidopropyl)dimethylammonium)butane-1-sulfonate, [3-(acryloyl)oxy)propyl](dimethylammonio)acetate, dimethylaminopropyl methacrylamide or even derivatives, such as 2-((3-methylacrylamidopropyl)dimethylammonium)ethane-1-sulfonate, 3-((3-methyldimethylammonium)propane-1-sulfonate, 4-((3-acrylamidopropyl)dimethylammonium)butane-1-sulfonate, [3-(acryloyl)oxy)propyl](dimethylammonio)acetate, dimethylaminopropyl methacrylamide or even derivatives, such as 2-((3-methylacrylamidopropyl)dimethylammonium)ethane-1-sulfonate, 3-((3-methyldimethylammonium)propane-1-sulfonate dimethylammonio)propane-1-sulfonate), 4-((3-methacrylamidopropyl)dimethylammonio)butane-1-sulfonate and [3-(methacryloyloxy)](dimethylammonio)propyl acetate and mixtures thereof.

[0096] The applicant describes other zwitterionic monomers in document WO2021123599.

[0097] The base polymer according to the invention advantageously comprises zwitterionic monomers C in an amount of from 0.001 to 30 mol %, preferably from 0.01 to 20 mol %, more preferably from 0.1 to 15 mol %.

[0098] Advantageously, the one or more hydrophobic monomers C may be selected from the group consisting of: 30 Alkyl chain, arylalkyl (C4-C 30 Alkyl, C4-C 30 Esters of (meth)acrylic acid having a propoxylated, ethoxylated, or ethoxylated and propoxylated (meth)acrylic acid having a C1-C3 alkyl chain, an arylalkyl (C4-C 30 Alkyl, C4-C 30 Aryl) or dialkyl (C4-C 30 alkyl) propoxylated, ethoxylated, ethoxylated and propoxylated (meth)acrylamide derivatives; alkylaryl sulfonates (C4-C 30 Alkyl, C4-C 30 aryl), or having C4-C 30 Alkyl chain, arylalkyl (C4-C 30 Alkyl, C4-C 30 aryl) propoxylated, ethoxylated, or ethoxylated and propoxylated (meth)acrylamide mono- or di-substituted amides; having C4-C 30 Alkyl chain, arylalkyl (C4-C 30 Alkyl, C4-C 30 Aryl) or C4-C 30 Dialkyl propoxylated, ethoxylated, ethoxylated and propoxylated (meth)acrylamide derivatives; alkyl aryl sulfonates (C4-C 30 Alkyl, C4-C 30 aryl) and mixtures thereof.

[0099] The base polymer generally comprises less than 1 mol % of hydrophobic monomers C. The base polymer may be free of hydrophobic monomers C.

[0100] When the base polymer according to the invention comprises one or more hydrophobic monomers C, these are present in such an amount that the polymer remains water-soluble.

[0101] A person skilled in the art will adjust the amounts of the different monomers so as not to exceed 100 mol % during the preparation of the base polymer. Preferably, monomers A and B represent 100 mol % of the monomers of the base polymer.

[0102] Structured system

[0103] The structuring system of the base polymer consists of:

[0104] (i) at least one compound I;

[0105] (ii) at least one compound II.

[0106] Compound I is advantageously selected from the group consisting of allylsulfonic acid, methallylsulfonic acid, disulfonic acid, disulfonic methallyl acid, their salts and mixtures thereof, preferably compound I is methallylsulfonic acid, for example sodium methallylsulfonate.

[0107] The salted form advantageously corresponds to an alkali metal salt (Li, Na, K...), an alkaline earth metal salt (Ca, Mg...) or an ammonium salt (eg ammonium ion or tertiary ammonium). The sodium salt is the preferred salt.

[0108] The base polymer advantageously comprises from 500 to 50,000 ppm, preferably from 1,000 to 20,000 ppm, more preferably from 2,000 to 10,000 ppm of compound I, based on the total weight of monomers A and B (+ optionally monomers C) of the base polymer.

[0109] Compound II used in the context of the present invention has the formula (1):

[0110]

[0111] R1 and R2 are independently a hydrogen atom, a methyl group, an ethyl group, an isopropyl group or a CH2-OH group;

[0112] R1 and R2 are not both hydrogen atoms (when R2=H, R1≠H; when R1=H, R2≠H).

[0113] The compound II used is advantageously chosen from the group consisting of N,N-dimethylacrylamide, N,N-diethylacrylamide, N,N-isopropylacrylamide, N-methylolacrylamide and mixtures thereof. Preferably, compound II is N,N-dimethylacrylamide.

[0114] The base polymer according to the invention advantageously comprises from 500 to 50,000 ppm, preferably from 1,000 to 20,000 ppm, more preferably from 2,000 to 10,000 ppm of compound II, based on the total weight of monomers A and B (+ optionally monomers C) of the base polymer.

[0115] The mass ratio of compound I to compound II in the base polymer is advantageously from 0.01 to 100, preferably from 0.1 to 10.

[0116] In a preferred embodiment of the present invention, the amount of compound I is greater than that 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.

[0117] Optional

[0118] The base 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) or from monomers having at least two epoxy functional groups, such as polyethylenically unsaturated monomers, vinyl functional groups, specifically allyl functional groups, acrylic acid functional groups. For example, methylenebisacrylamide (MBA), triallylamine, tetraallyl ammonium chloride, 1,2-dihydroxyethylenebis(N-acrylamide) and mixtures thereof may be cited. Preferably, the crosslinking agent is methylenebisacrylamide (MBA).

[0119] The amount of crosslinker in the base polymer is advantageously from 5 to 5,000 ppm, more preferably from 50 to 3,000 ppm, based on the total weight of monomers A and B (+ optionally monomers C) of the base polymer.

[0120] In a particular embodiment according to the invention, the base polymer does not comprise a crosslinker.

[0121] The base polymer according to the present invention may also contain at least one transfer agent, for example selected from the following: methanol, isopropanol, sodium hypophosphite, 2-mercaptoethanol and mixtures thereof. Other transfer agents may also be listed, including xanthates, dithiocarbonates, dithiocarbamates and trithiocarbonates and mixtures thereof, preferably the transfer agent is sodium hypophosphite.

[0122] The amount of crosslinker in the base polymer is advantageously comprised between 10 and 10,000 ppm, more preferably between 50 and 5,000 ppm, based on the total weight of monomers A and B (+ optionally monomer C) of the base polymer.

[0123] In a particular embodiment according to the invention the base polymer does not comprise a transfer agent.

[0124] Physical properties of base polymers

[0125] The weight average molecular weight of the base 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.

[0126] The weight average molecular weight is preferably measured by gel permeation chromatography coupled to a MALS detector.

[0127] The base polymer is advantageously obtained and used in liquid form.

[0128] The viscosity of the solution containing the base polymer is advantageously from 1,000 to 50,000 cps, preferably from 3,000 to 20,000 cps, for example from 5,000 to 20,000 cps.

[0129] Renewable sources

[0130] In a preferred embodiment according to the invention, the polyvinylamine polymers are prepared using monomers of at least partly renewable and non-fossil origin.

[0131] In the context of the present invention, the phrase "renewable and non-fossil origin" means a source of a compound derived from biomass or syngas, i.e. the result of one or more chemical transformations performed on one or more raw materials of natural and non-fossil origin. The term "bio-sourced" or "bio-resourced" may also be used to characterize a renewable and non-fossil source of a compound. A renewable and non-fossil source of a compound includes renewable and non-fossil raw materials from a circular economy and which have been previously recycled one or more times in a recycling process of material from biomass, such as material from polymer depolymerization or from pyrolysis oil conversion.

[0132] According to the present invention, "at least partially of renewable and non-fossil origin" means that the content of biogenic carbon is from 5 wt.% to 100 wt.%, preferably at least 30%, more preferably at least 50%, even more preferably at least 70%, more preferably at least 90%, even more preferably at least 100% biogenic carbon, based on the total carbon weight of the compound.

[0133] In the context of the present invention, standard ASTM D6866-21, method B is used to indicate the biogenic nature of a compound and to determine the biogenic content of said compound. This value is expressed as a weight percentage of biogenic carbon based on the total weight of carbon in said compound.

[0134] gradient

[0135] The base polymer and the polyvinylamine polymer according to the present invention are gradient polymers.

[0136] A polymer with a gradient structure is a polymer composed of at least two monomers in which 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, inter-chain and intra-chain repulsions are rarely observed because the composition changes gradually over the length of the polymer chain.

[0137] Gradients can be formed by spontaneous or forced gradients. Spontaneous gradient polymerizations are due to different monomer reactivities. Forced gradient polymerizations involve varying the composition of the monomers introduced throughout the polymerization time.

[0138] The gradient forced process comprises (1) introducing a first portion of monomers into a reactor, (2) adding at least one additional monomer portion (which is advantageously different from the first component), and (3) polymerizing the monomers introduced into the reactor. The monomers begin to polymerize upon introduction of the first portion.

[0139] The addition of additional monomer portions can be carried out in parallel with the introduction of the first portion of monomers into the reactor (therefore, the introduction of the portions can start and end simultaneously). Alternatively, the first monomer (first portion) can be fed into the reactor before the second monomer portion is added. Alternatively, the first portion and the second portion can be introduced simultaneously, but the time used to add the second portion may be longer than the time used to add the first portion into the reactor. This embodiment is also applicable to methods with at least 3 monomer portions.

[0140] According to the process of the present invention, the polyvinylamine polymer obtained is formed by stepwise addition of monomers, ie, preferably a forced gradient method.

[0141] 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. Different parts refer to parts with different monomer compositions (ratios and / or properties of monomers) and / or compounds I and II (ratios and / or properties of compounds I and II).

[0142] Aggregation methods

[0143] The polyvinylamine polymer is obtained according to the following steps:

[0144] 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;

[0145] b) subjecting part F1 to polymerization 1 (PO1) to form a solution of a first gradient polymer (PG1);

[0146] 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;

[0147] d) polymerizing part F2 on PG1 (PO2) to form a solution of a second gradient polymer (PG2);

[0148] 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;

[0149] f) polymerizing part F3 on PG2 (PO3) to form a solution comprising the base polymer;

[0150] g) diluting the solution containing the base polymer and subjecting the base polymer to a Hofmann degradation reaction to obtain a polyvinylamine polymer.

[0151] The process may comprise adding an additional portion, but no additional portion is added after step g) of the Hofmann degradation.

[0152] It is possible that the improved properties of the polymers obtained according to the process of the invention may be due to the fact that the polymerization is carried out stepwise and continuously, ie without interruptions.

[0153] "Stepwise" means that the polymerization of the base polymer monomers is carried out in multiple parts (without interruption), that is, the parts are added continuously and the polymerization is not stopped. The different steps a) to f) are carried out step by step. That is, 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 so as to obtain the base polymer at the end of the polymerization. At least one of parts F1, F2 and F3 is different from the other parts. Preferably, parts F1, F2 and F3 are different. Adding different parts in the polymerization method makes it possible to obtain a gradient of the base polymer composition.

[0154] In certain embodiments, the polymerization can be stopped after PO1 and / or PO2 and continued at a different location. In this embodiment, the addition to the gradient polymer PG formed during one or more of the previous steps is X Part F X+1 (X=1 or 2) polymerized with PG X interact to form PG X+1 , and the process continues in the following steps to finally obtain the base polymer.

[0155] After the polymerization is completed, the base polymer is subjected to step g). Step g) can be carried out continuously until the polymerization is completed, or at another time (later). Preferably, step g) is carried out continuously until PO3. That is, the base polymer used in step g) is no longer subjected to polymerization. However, the base polymer used in step g) is subjected to a post-treatment to change its chemical structure. Step g) is advantageously carried out in a reactor different from the polymer base synthesis reactor, because it is necessary to dilute the solution containing the base polymer. The dilution of the base polymer is advantageously carried out in water.

[0156] The Hofmann degradation of step g) is advantageously carried out on polymers having amide groups.

[0157] In the polymerization process according to the invention, the sum of the mole percentages of the monomers of the different fractions is equal to the sum of the mole percentages of the monomers of the polyvinylamine polymer.

[0158] Step a), forming a solution (S1) comprising a first part (F1)

[0159] Solution (S1)

[0160] Solution S1 typically contains:

[0161] - solvent;

[0162] - initiator;

[0163] -Part I F1.

[0164] The solvent is advantageously water, or a solvent in which the monomers and base polymer are soluble. Preferably, the solvent is water.

[0165] The polymerization initiator used can be any compound which 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 multiple polymerization initiators, for example, a mixture of a redox catalyst and an azo compound. A preferred initiator is a persulfate.

[0166] In a particular embodiment, solution S1 is formed by mixing solvent, initiator, and fraction F1 in a polymerization reactor.

[0167] In this particular embodiment, part F1 can be added all at once, in several portions or poured (in flowing form), ie gradually and continuously (eg dropwise) into the solvent / initiator mixture. Preferably, part F1 is added all at once to the polymerization reactor.

[0168] In a particular embodiment of the invention, the initiator and part F1 are poured (in flowing form) into the polymerization reaction containing the solvent. They can be added separately or premixed. Preferably, they are added separately.

[0169] In a preferred embodiment of the invention, the initiator is added continuously throughout the polymerization process. In this case, the initiator is advantageously added in parallel with the different parts during the different polymerization steps and in the possible aging steps of the different gradient polymers (PG1 and PG2) and the base polymer.

[0170] In this preferred embodiment of the invention, the duration of the initiator pour is from 50 minutes to 560 minutes, preferably from 130 minutes to 430 minutes.

[0171] Part 1 (F1)

[0172] Advantageously, fraction F1 comprises from 10 to 45% by weight, preferably from 15 to 40% by weight, of monomers (A and / or B, + optionally C), based on the total weight of monomers (A and / or B, + optionally C) of the base polymer.

[0173] Fraction F1 advantageously comprises from 0 to 65 mol %, preferably from 5 to 55 mol %, of one or more cationic monomers A, based on the total number of moles of monomers in fraction F1.

[0174] Fraction F1 advantageously comprises from 35 to 100 mol %, preferably from 45 to 95 mol %, of one or more nonionic monomers B, based on the total number of moles of monomers in fraction F1.

[0175] Fraction F1 advantageously comprises from 250 to 30,000 ppm, preferably from 500 to 10,000 ppm and more preferably from 1,000 to 7,000 ppm of compound I, based on the total weight of monomers A and B (+optionally monomers C) of the base polymer.

[0176] Fraction F1 advantageously comprises from 250 to 30,000 ppm, preferably from 500 to 10,000 ppm, more preferably from 1,000 to 5,000 ppm of compound II, based on the total weight of monomers A and B (+ optionally monomers C) of the polyvinylamine polymer.

[0177] The different monomers and compounds constituting part F1 are advantageously added in the form of solutions. These solutions can be added individually or in the form of a mixture, once, in several additions or poured (in a flowing form) into the polymer reactor to form solution S1. Preferably, the addition is carried out in the form of a mixture and once.

[0178] When pouring (in flowing form) fraction F1 , this pouring advantageously lasts from 10 minutes to 80 minutes, preferably from 40 minutes to 70 minutes.

[0179] In a preferred embodiment, fraction F1 is prepared in a reactor (polymerization reactor) before the initiator is added.

[0180] In a preferred embodiment, fraction F1 contains at least one monomer B, at least one compound I and at least one compound II.

[0181] In a preferred embodiment, fraction F1 contains at least one monomer A, at least one monomer B, at least one compound I and at least one compound II.

[0182] Step b), polymerizing part F1 to form a first gradient polymer (PG1)

[0183] Polymerization 1 (PO1)

[0184] Prior to polymerizing PO1, the air in the polymerization reactor may be replaced with an inert gas such as nitrogen or argon.

[0185] The polymerization PO1 is usually a free radical polymerization. A polymerization initiator may be used, in particular an initiator which dissociates into free radicals under the polymerization conditions.

[0186] The polymerization PO1 is usually initiated at a temperature of 70 to 90°C, preferably 75 to 85°C, and then the polymerization temperature is controlled using a cooling device so as not to exceed 95°C.

[0187] The polymerization PO1 preferably lasts from 10 minutes to 70 minutes.

[0188] Advantageously, the polymerization begins when the first monomer, the solvent and the initiator are brought into contact, that is to say the duration of the polymerization PO1 advantageously corresponds to the duration of the pouring of the fraction F1 .

[0189] Gradient polymer (PG1)

[0190] At the end of the polymerization of PO1, a gradient polymer (PG1) is obtained.

[0191] In a specific embodiment of the present invention, the gradient polymer PG1 is left to age for 5 minutes to 60 minutes, preferably 10 minutes to 30 minutes.

[0192] "Standing aging" means that after the polymerization is completed, the temperature of the medium is maintained at 80 to 90°C in order to increase the viscosity through the internal branching phenomenon of the polymer. The definition of aging applies to all steps of the polymerization process. Step c) Adding the second part (F2) to the solution containing PG1

[0193] Part 2 F2

[0194] Advantageously, fraction F2 comprises from 30 to 80% by weight, preferably from 40 to 70% by weight, of monomers (A and / or B, + optionally C), based on the total weight of monomers (A and / or B, + optionally C) of the base polymer.

[0195] Fraction F2 advantageously comprises from 0 to 50 mol %, preferably from 0 to 40 mol %, of one or more cationic monomers A, based on the total number of moles of monomers in fraction F2.

[0196] Fraction F2 advantageously comprises from 0 to 100 mol %, preferably from 60 to 100 mol %, of one or more nonionic monomers B, based on the total moles of monomers in fraction F2.

[0197] Fraction F2 advantageously comprises from 250 to 30,000 ppm, preferably from 500 to 10,000 ppm, more preferably from 850 to 5,000 ppm, for example from 1,000 to 5,000 ppm of compound I, based on the total weight of monomers A and B (+ optionally monomers C) of the base polymer.

[0198] Fraction F2 advantageously comprises from 250 to 30,000 ppm, preferably from 500 to 10,000 ppm and more preferably from 1,000 to 5,000 ppm of compound II, based on the total weight of monomers A and B (+optionally monomers C) of the base polymer.

[0199] The different monomers and compounds constituting F2 are advantageously added in the form of solutions. The solutions can be added to the polymer reactor in one go, in multiple additions or pouring (in a flowing form) alone or in the form of a mixture. Preferably, the addition is carried out in the form of a mixture and pouring (in a flowing form).

[0200] Adding part F2 in a flowing form (eg dropwise) allows controlling the exotherm of the reaction which may otherwise be too high even when a cooler is used.

[0201] The pouring of fraction F2 advantageously lasts from 10 minutes to 100 minutes, preferably from 30 minutes to 90 minutes.

[0202] 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.

[0203] Step d), polymerizing part F2 on PG1 to form a second gradient polymer (PG2)

[0204] Polymerization (PO2)

[0205] 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.).

[0206] The polymerization PO2 advantageously lasts from 10 to 100 minutes, preferably from 30 to 90 minutes.

[0207] Polymerization PO2 starts with the addition of the first monomer of fraction F2.

[0208] Advantageously, the duration of polymerizing PO2 corresponds to the duration of pouring of fraction F2.

[0209] Gradient Polymer (PG2)

[0210] At the end of the polymerization of PO2, a gradient polymer (PG2) is obtained.

[0211] In a specific embodiment of the present invention, the PG2 link is left to age for 5 minutes to 60 minutes, preferably 10 minutes to 30 minutes.

[0212] Step e) adding the third part (F3) to the solution containing PG2

[0213] Section F3

[0214] Advantageously, fraction F3 comprises from 5 to 40% by weight, preferably from 10 to 30% by weight, of monomers (A and / or B, + optionally C), based on the total weight of monomers (A and / or B, + optionally C) of the base polymer.

[0215] Fraction F3 advantageously comprises from 0 to 50 mol %, preferably from 0 to 35 mol %, of one or more cationic monomers A, based on the total moles of monomers in fraction F3.

[0216] Fraction F3 advantageously comprises from 50 to 100 mol %, preferably from 65 to 100 mol %, of one or more nonionic monomers B, based on the total number of moles of monomers in fraction F3.

[0217] Fraction F3 advantageously comprises from 0 to 10,000 ppm, preferably from 10 to 5000 ppm and more preferably from 20 to 1,000 ppm of compound I, based on the total weight of monomers A and B (+optionally monomers C) of the base polymer.

[0218] Fraction F3 advantageously comprises from 0 to 10,000 ppm, preferably from 0 to 1,000 ppm, of compound II, based on the total weight of monomers A and B (+optionally monomers C) of the base polymer.

[0219] The different monomers and compounds constituting F3 are advantageously added in the form of solutions. These solutions can be added to the polymerization reactor all at once, in several additions or poured (in a flowing form) (i.e. dropwise) individually or in the form of a mixture. Preferably, the addition is carried out in the form of a mixture and poured (in a flowing form).

[0220] Adding part F3 in a flowing form (eg dropwise) allows controlling the exotherm of the reaction which may otherwise be too high even when a cooler is used.

[0221] The pouring of fraction F3 advantageously lasts from 10 minutes to 100 minutes, preferably from 30 minutes to 90 minutes.

[0222] In a preferred embodiment, fraction F3 contains at least one monomer B and at least one compound I.

[0223] In an embodiment, the amount of compound I in fraction F3 is less than 500 ppm, preferably less than 300 ppm, preferably less than 200 ppm, even more preferably less than 100 ppm.

[0224] Such small amounts enable desired physical and unique properties to be achieved in the base polymer and subsequently the final polyvinylamine polymer.

[0225] Step f), polymerizing part F3 on PG2 to form a base polymer

[0226] Polymerization (PO3)

[0227] The polymerization of PO3 is carried out in continuation of the polymerization of PO2; the polymerization of PO3 is carried out under the same conditions of time and temperature as PO2 (advantageously, 70 to 90° C. for 10 to 100 minutes, preferably 30 to 90 minutes).

[0228] Polymerization PO3 starts with the addition of the first monomer of fraction F3.

[0229] Advantageously, the duration of polymerizing PO3 corresponds to the duration of pouring of fraction F3.

[0230] At the end of the polymerization of PO3, the base polymer is obtained.

[0231] In a particular embodiment of the invention, the base polymer is left to age for 5 to 60 minutes, preferably 10 to 30 minutes, before removing the residual monomers.

[0232] The reaction is stopped by adding excess initiator and / or water; this step serves to eliminate any residual monomers that may be present in the solution comprising the base polymer.

[0233] Optional Steps

[0234] The method according to the present invention may also include additional steps and is not limited to the above steps.

[0235] In a particular embodiment of the present invention, the polymerization process according to the invention may comprise the addition of additional moieties constituting the base polymer.

[0236] In a preferred embodiment of the invention, after step f) of polymerizing PO3 and before step g), the base polymer is left to age for 10 to 100 minutes, preferably 30 to 90 minutes. In case of adding additional parts, the ageing is carried out after the last polymerization step and before step g).

[0237] In a particular embodiment of the invention, a crosslinking agent and / or a transfer agent is added during at least one of the above steps.

[0238] In a particular embodiment of the invention, a cross-linking agent is added to fraction F1 and / or fraction F2.

[0239] When a crosslinking agent is added, it is advantageously selected from the crosslinking agents described above.

[0240] When a crosslinking agent is added, the amount of crosslinking agent is advantageously from 5 to 5,000 ppm, preferably from 50 to 3,000 ppm, based on the total weight of the base polymer (monomers A, B and optionally C).

[0241] In a particular embodiment of the invention, a transfer agent is added to fraction F1 and / or fraction F2.

[0242] When a transfer agent is added, it is advantageously selected from the transfer agents described above.

[0243] When a transfer agent is added, the amount of transfer agent is advantageously from 10 to 10,000 ppm, preferably from 50 to 5,000 ppm, based on the total weight of the base polymer (monomers A, B and optionally C).

[0244] Step g) subjects the base polymer to a Hofmann degradation reaction to obtain a polyvinylamine polymer.

[0245] The Hofmann degradation reaction involves the conversion of an amide or nitrile functionality into an amine functionality (e.g., by forming a vinylamine monomer unit) using two main coefficients (expressed as a molecular ratio);

[0246] - coefficient α=hypohalite (alkali metal hypohalite and / or alkaline earth metal hypohalite) / amide and / or nitrile function;

[0247] - Factor β=hydroxide (alkali metal hydroxide and / or alkaline earth metal hydroxide) / hypohalite (alkali metal hypohalite and / or alkaline earth metal hypohalite).

[0248] Hypohalites are oxygen-containing anions, such as hypochlorite C1O - Preferably, the hypohalite will be sodium hypochlorite.

[0249] "Alkaline hypohalite" is a hypohalite of at least one alkali metal, such as NaOCl, KOBr or NaOCl+KOBr. The same is true for alkaline earth metal hypohalites.

[0250] "Alkaline" is used to denote an alkali metal, advantageously lithium, sodium or potassium.

[0251] "Earth-alkaline" is used to denote an alkaline earth metal, advantageously calcium or magnesium.

[0252] The term "alkaline hydroxide" is used to refer to a hydroxide of at least one alkali metal (OH - ), for example, NaOH, KOH or NaOH+KOH. The same is true for alkaline earth metal hydroxides. Preferably, the alkali metal hydroxide will be sodium hydroxide.

[0253] Advantageously, the Hofmann degradation reaction comprises at least the following steps:

[0254] g1) diluting (advantageously in water) a solution comprising a base polymer so as to form a diluted base polymer solution (SD1);

[0255] g2) adding hypohalite and hydroxide to SD1 to form a diluted solution (SD2);

[0256] g3) performing a reaction between the base polymer, the hypohalite and the hydroxide;

[0257] g4) obtaining a solution (SD3) comprising a polyvinylamine polymer.

[0258] Advantageously, in step g1), the concentration of the base polymer in the diluted solution SD1 of base polymer is from 1 to 40% by weight, more preferably from 2 to 30% by weight, even more preferably from 5 to 25% by weight, based on the weight of SD1.

[0259] Advantageously, in step g2), the alpha coefficient = hypohalite / amide and / or nitrile functions, the alpha coefficient is from 0.1 to 1.0, preferably from 0.3 to 1.0, more preferably from 0.5 to 1.0.

[0260] Advantageously, in step g2), the β coefficient = hydroxide / hypohalite, the β coefficient is between 0.5 and 4.0.

[0261] Advantageously, in step g3), the reaction between the base polymer, the hypohalite and the hydroxide lasts from 10 seconds to 180 minutes, preferably from 1 minute to 120 minutes, more preferably from 10 minutes to 90 minutes, even more preferably from 30 minutes to 75 minutes.

[0262] Advantageously, in step g3), the reaction between the base polymer, the hypohalite and the hydroxide is carried out at a temperature ranging from 10 to 30°C, preferably from 15 to 25°C.

[0263] At the end of step g3), a polyvinylamine polymer according to the invention is obtained.

[0264] In a particular embodiment of the invention, at the end of step g3), the polyvinylamine polymer may be functionalized with a dialdehyde so as to form an aldehyde-functionalized polymer (advantageously glyoxalated).

[0265] The dialdehyde is advantageously selected from glyoxal, glutaraldehyde, furan dialdehyde, adipaldehyde, succinaldehyde, dialdehyde starch, 2,2-dimethoxyacetaldehyde, diepoxides and mixtures thereof. Preferably, the dialdehyde is glyoxal.

[0266] In order to stabilize the generated amine functions, a person skilled in the art can add to the diluted solution SD1 at least one quaternary ammonium derivative as described in document JP 57077398. This quaternary ammonium derivative is intended to prevent the reaction between the amine functions and the residual amide functions. Furthermore, the addition of these reagents can be carried out individually, simultaneously, mixed or non-mixed, in any order of introduction, at one or more injection points. The addition of these reagents is advantageously carried out during step g1).

[0267] In a preferred embodiment of the invention, the pH of solution SD3 is adjusted to between 0.5 and 7.5, more preferably between 1.0 and 3.0, by adding an acid. The pH adjustment is advantageously carried out when the polyvinylamine polymer is not functionalized with a compound comprising at least two aldehyde functions.

[0268] During the Hofmann degradation process, the cationicity of the base polymer increases due to the total or incomplete use / consumption of the alkali metal hypohalite or alkaline earth metal hypohalite.

[0269] The cationic charge density of the polyvinylamine polymer is advantageously greater than 2 meq / g, preferably greater than 5 meq / g, advantageously less than 12 meq / g, preferably less than 11.5 meq / g.

[0270] In a particular embodiment of the invention, the microcellulose compound is reacted with a polyvinylamine polymer.

[0271] Advantageously, the microcellulose compound is in the form of a suspension in water.

[0272] Advantageously, during the reaction with the microcellulose compound, the mass concentration of the polyvinylamine polymer in the aqueous solution is between 0.5 and 20%, preferably between 1 and 5%.

[0273] The reaction between the microcellulose compound and the polyvinylamine polymer is advantageously carried out without the polyvinylamine polymer being functionalized with a dialdehyde.

[0274] The reaction between the microcellulose compound and the polyvinylamine polymer is advantageously carried out at a temperature of from 10 to 60°C, preferably from 20 to 40°C.

[0275] Advantageously, the microcellulose compound is selected from the group consisting of nanofibrillated cellulose, microfibrillated cellulose, nanocrystalline cellulose, nanocellulose.

[0276] Advantageously, 10 to 100 wt. %, preferably 10 to 50 wt. %, of the microcellulose compound is added to the polyvinylamine polymer, based on the weight of the polyvinylamine polymer.

[0277] Even if the polyvinylamine polymer is prepared in solution, the polyvinylamine polymer of the invention can also be used in solid form. Under these conditions, the solid form contains not only the polymer but also a portion of the salts obtained at the end of the Hofmann degradation. In practice, the polyvinylamine polymer in solid form is obtained in other ways (by a process comprising drying the solution in step g)). The technical principle of solid / liquid separation is by atomization or spray drying (which consists in producing a cloud of fine droplets in a hot gas stream for a controlled period of time), drum drying, fluidized bed dryer...

[0278] Papermaking method

[0279] The present invention also relates to a process for making paper or paperboard, comprising (1) adding a polyvinylamine polymer according to the present invention to an aqueous solution of fibers, and (2) forming the paper or paperboard. Thus, the present invention relates to the use of a polyvinylamine polymer in a papermaking process.

[0280] The different steps in the paper production process, paperboard production process or the like are known and correspond to the art which is part of the knowledge of the person skilled in the art and it is not necessary to describe these steps in further detail, as they are known and classical within the scope of the knowledge of the person skilled in the art. If necessary, the person skilled in the art can refer to the document: Handbook for Pulp & Paper Technologists, 4th edition, GASmook.

[0281] According to the invention, the polyvinylamine polymer is added in the papermaking process before or after forming paper, paperboard or the like. Thus, contacting the cellulosic material with the polymer of the invention can be carried out in different ways, in particular according to typical methods known to those skilled in the art.

[0282] The polyvinylamine polymer may be added to the cellulosic material in the form of a diluted or undiluted aqueous solution.The polyvinylamine polymer may be applied by an impregnation technique or may be added directly to the fiber suspension in the papermaking process anywhere dry strength agents are normally introduced.

[0283] Thus, the polymer according to the invention can be introduced into a thick stock or a thin stock. The polymer according to the invention can be added at the mixing pump, before the headbox or before the filter screen. Preferably, the polymer is introduced before the headbox.

[0284] Preferably, the polymer according to the invention is injected industrially into the fiber suspension, ie before it is diluted with white water (thick stock).The consistency of the stock is about 1 to 5% by mass of cellulose fibers.

[0285] The papermaking process according to the invention can be carried out with any type of pulp, for example virgin fiber pulp (kraft, bisulfite), recycled fiber, deinked pulp, mechanical pulp and thermomechanical pulp.

[0286] The polyvinylamine polymer is advantageously added directly to the fiber suspension prior to forming the paper.

[0287] The polyvinylamine polymer can be added at a single injection point or at two injection points.

[0288] If desired, the papermaking process according to the invention may also comprise the addition of other additives and / or polymers; as non-limiting examples we may mention: biocides, coagulants, retention aids, flocculants, starch.

[0289] use

[0290] The invention also relates to the use of the polyvinylamine polymer in the recovery of hydrocarbons (oil and / or gas); in drilling or cementing wells (especially hydrocarbon wells); in the stimulation of hydrocarbon wells (oil and / or gas), for example, in 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 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 formulation of detergents; in textile manufacture; in the geothermal field; in the manufacture of sanitary napkins; or in agriculture.

[0291] The invention also relates to the use of polyvinylamine polymers as flocculants, coagulants, binders, fixatives, viscosity reducers, thickeners, absorbents, friction reducers, drainage agents, charge retention agents, dehydrating agents, conditioners, stabilizers, fixatives, film formers, sizing agents, superplasticizers, clay inhibitors or dispersants.

[0292] The invention and the advantages resulting from the present invention will be more clearly shown in the following examples, which are intended to illustrate the invention but are not intended to limit its use.

[0293] Example

[0294] List of abbreviations:

[0295] DADMAC: Diallyldimethylammonium (Monomer A)

[0296] AMD: Acrylamide (Monomer B)

[0297] DMAM: dimethylacrylamide (compound II)

[0298] SMS: Sodium methyl allyl sulfonate (Compound I)

[0299] SPS: Sodium persulfate (polymerization initiator)

[0300] MBA: Methylene bisacrylamide (cross-linking agent)

[0301] PEI: Polyethyleneimine

[0302] Description of GPC-MALS Molecular Weight Characterization

[0303] Gel permeation chromatography is a method for separating macromolecules based on their hydrodynamic volume; gel permeation chromatography combined with MALS detection allows the diffusion of light to be measured from multiple angles.

[0304] The synthetic polymers were analyzed under the following conditions:

[0305] -Instrument: GPC-2

[0306] - Column: Shodex SB-807-HQ and SB-805 customized

[0307] -method:

[0308] * Temperature: 30℃

[0309] * Mobile phase: 0.5M NaNO3, HEPES (pH=8), 100ppm NaN3

[0310] * Injection: 100 μL

[0311] * Flow rate: 0.3mL / min

[0312] * Detection:

[0313] (i) Light diffusion detector (MALS): absolute molar mass

[0314] (ii) Refractometer (RI): Concentration

[0315] The viscosity was measured at 25°C using a Brookfield viscometer with a Brookfield LV1 module at a speed of 60 rpm.

[0316] Preparation of polymer 1 according to the invention (P1(INV))

[0317] Polymer 1 (P1)

[0318] Step 1: Gradient Polymer PG1

[0319] In a 1 liter reactor equipped with a mechanical stirrer, a thermometer, a condenser and a nitrogen-impregnated rod, a first portion F1 is introduced at the bottom of the reactor, consisting of: 146.9 g of water, 50.6 g of acrylamide (50% by weight in water), 77.1 g of dimethyldiallylammonium chloride (64% by weight in water), 1 g of citric acid, 0.5 g of dimethylacrylamide and 0.4 g of sodium methallylsulfonate. The medium is heated and maintained at a temperature of 79 to 81° C. using a water bath. The addition of 0.05 g of sodium persulfate makes it possible to initiate the initiator and start the polymerization of the monomers (PO1) so as to form a solution of a first gradient polymer PG1.

[0320] Step 2: Gradient Polymer PG2

[0321] When the exothermic reaction is over, pouring begins: the initiator (50 g SPS, 0.33 wt % aqueous solution) is poured over 130 minutes, and at the same time, the second part F2 is poured over 50 minutes, which consists of: 25.5 g water, 101.3 g acrylamide (50 wt % aqueous solution), 77.1 g DADMAC (64 wt % aqueous solution), 0.5 g dimethylacrylamide and 0.19 g sodium methallyl sulfonate. After pouring part F2, the gradient polymer PG2 is left to age for 10 minutes (during pouring part F2 and during aging, polymerization PO2 is carried out to form the gradient polymer PG2).

[0322] Step 3: Base Polymer

[0323] We then start pouring the third part F3 over 60 minutes, which consists of: 121.3 g of water, 50.6 g of acrylamide (50% by weight in water), 0.01 g of sodium methyl allyl sulfonate. At the end of the addition of part F3, the polymer is left to age for 10 minutes (polymerization PO3 is carried out during the pouring of part F3 and during the ageing to form the base polymer).

[0324] After aging was complete, 146.9 g of water and 0.15 g of sodium persulfate were added. When the desired viscosity was reached, the reaction was stopped by adding 0.6 g of sodium bisulfite (40 wt. % in water) and 146.9 g of water. A new aging cycle of 60 minutes was applied before cooling. The solution obtained containing base polymer 1 had a pH of 3.5 and 20 wt. % active matter, a viscosity of 3500 cps and a molecular weight of 2,650,000 Da obtained by GPC-MALS.

[0325] Hofmann degradation: polymer 1 (P1)

[0326] The Hofmann degradation is carried out according to the applicant's method described in document WO 2010061082. At the end of the Hofmann degradation, a polyvinylamine polymer (P1 (INV)) according to the invention is obtained.

[0327] Preparation of Comparative Examples Polymers 2 to 3 (CE1 to CE2)

[0328] Polymer 2 (CE1)

[0329] According to Example E of document WO2011015783, polymer 2 (CE1) was obtained by Hofmann degradation reaction.

[0330] Polymer 3 (CE2)

[0331] Polymer 3 (CE2) was prepared according to the same protocol as polymer 1, but with only 2 steps.

[0332] The compositions of the different parts of the polymerization process of polymer 1 (P1) according to the invention and comparative polymers (CE1 to CE2) are summarized in Table 1a.

[0333] In this Table 1a, the monomer content described in each part represents the molar weight percentage of AMD (or DADMAC) monomer relative to the total molar amount of the corresponding monomer in the total part. Thus, for example, the sum of the percentages of AMD monomer in the three parts equals 100%.

[0334] The contents of compounds I (SMS) and II (DMAM) are expressed in ppm by weight, based on the total weight of the monomer or monomers in the three fractions.

[0335]

[0336] Table 1a: Composition of the part of the polymerization process to obtain polymer P1 and comparative examples P2 to P3 (CE1 to CE2).

[0337] The physicochemical properties of the obtained base polymers P1 and CE1 to CE2 are described in Table 1b below:

[0338] Table 1 b: Physicochemical properties of base polymer P1 according to the invention and comparative examples CE1 to CE2.

[0339] We observe differences and benefits provided by the present invention compared to the prior art, particularly with respect to the molecular weight of the base polymer (even though the viscosity is of the same order of magnitude).

[0340] Table 1c below shows the viscosity results of the final polymers obtained after the Hofmann degradation reaction.

[0341]

[0342] Table 1c: Comparison of the viscosity of the inventive polymer P1 and comparative examples CE1 to CE3 after Hofmann degradation.

[0343] The process of the present invention provides a polymer solution having the viscosity required and typical for papermaking processes while having a high molecular weight compared to conventional polymerization processes.

[0344] Application Testing

[0345] The wet pulp used in all application examples was obtained by disintegrating dry pulp in order to obtain a final water concentration of 1%. This was a pH neutral pulp with 100% recycled paperboard fibers. Evaluation of the Drainage Vacuum (DDA) performance

[0346] The DDA (Dynamic Drainage Analyzer) allows the automatic determination of the time (in seconds) required for vacuum dewatering of the fiber suspension on the fabric. The polymer was added to the wet pulp (0.6 liters of pulp, 1.0 mass %) in the DDA drum under stirring at 1000 rpm:

[0347] T=0s:Stirring pulp

[0348] T = 10s: Add one or more polymers

[0349] T=30s: Stop stirring and drain under vacuum for 60 seconds at 200 mbar.

[0350] The pressure under the fabric is recorded as a function of time. As the water is drained from the fiber mat, air passes through it, which causes a sudden change in slope on the curve representing the pressure under the fabric as a function of time. The time (expressed in seconds) associated with this sudden change in slope on the curve corresponds to the drainage time. Therefore, the shorter this time, the better the vacuum drainage.

[0351] Performance in dry-resistant applications, basis weight 80 g·m -2

[0352] The necessary amount of pulp is sampled in order to obtain a pulp having a final density of 80 g·m -2 Basis weight of paper.

[0353] The wet pulp is introduced into the dynamic handsheet former tank and kept under stirring. According to a predetermined sequence, different compounds are injected into the pulp. Typically, there is a contact time of 30 to 45 seconds between the addition of polymers.

[0354] Making paper handsheets with an automatic dynamic handsheet former: The blotter paper and the formed fabric were placed in the tank of the dynamic handsheet former before starting the rotation of the tank at 1000 rpm and building a water wall. The treated pulp was distributed on the water wall to form a fiber mat on the formed fabric.

[0355] After the water was drained off, the fiber mat was recovered, pressed at a pressure of 4 bars and then dried at 117° C. The paper obtained was packaged overnight in a room with controlled humidity and temperature (50% relative humidity and 23° C.). The drying resistance properties of all the papers obtained by this procedure were then measured.

[0356] The burst strength was measured using a Messmer Buchel M 405 burst tester according to TAPPI T403 om-02 standard.

[0357] The breaking length in the dry state was measured according to TAPPI T494 om-01 using a machine with a Testometric AX pulling device.

[0358] The amount of polymer added is expressed as kg active polymer per ton of dry fibre.

[0359] Trials with 1 kg / t and 1.5 kg / t were performed and are summarized in Table 2. The results are expressed as a percentage of the increase compared to the blank (no polymer).

[0360]

[0361] Table 2: Drainage and dry strength results for polymer 1 according to the invention (INV) and comparative polymers 2 to 3 (CE1 to CE2)

[0362] It is interesting to note that the polymers of the present invention exhibit improved drainage performance (DDA) and mechanical properties (burst; DBL; break in dry state) over the most effective products on the market.

Claims

1. A polyvinylamine polymer obtained by Hofmann degradation of a base polymer, comprising: - at least one cationic monomer A; - at least one nonionic monomer B selected from the group consisting of acrylamide, acrylonitrile, methacrylamide and mixtures thereof; - At least one structured system comprising: (i) at least one compound I 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 formula (1): 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 does not contain anionic monomers other than compound I; The polyvinylamine polymer is obtained according to 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) 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 (PO3) to form a solution comprising the base polymer; g) diluting the solution comprising the base polymer and subjecting the base polymer to a Hofmann degradation reaction to obtain a polyvinylamine polymer and 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.

2. The polyvinylamine polymer according to claim 1, characterized in that The at least one cationic monomer A is selected from the group consisting of dimethyldiallylammonium chloride, acrylamidopropyltrimethylammonium chloride, methacrylamidopropyltrimethylammonium chloride and mixtures thereof.

3. The polyvinylamine polymer according to any one of the preceding claims, characterized in that The base polymer contains 500 to 50,000 ppm of compound I, based on the total weight of monomers A and B.

4. The polyvinylamine polymer according to any one of the preceding claims, characterized in that Based on the total weight of monomers A and B, the base polymer contains 500 to 50,000 ppm of compound II.

5. The polyvinylamine polymer according to any one of the preceding claims, characterized in that Compound II is selected from the group consisting of N,N-dimethylacrylamide, N,N-diethylacrylamide, N,N-isopropylacrylamide, N-methylolacrylamide, and mixtures thereof.

6. The polyvinylamine polymer according to any one of the preceding claims, characterized in that The mass ratio between compound I and compound II is 0.01 to 100.

7. The polyvinylamine polymer according to any one of the preceding claims, characterized in that At least one of the parts F1 , F2 or F3 is different from the other parts.

8. A method for gradually preparing a polyvinylamine polymer, comprising the steps of: 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; At least one monomer A is a cationic monomer; At least one monomer B is a nonionic monomer selected from the group consisting of acrylamide, acrylonitrile, methacrylamide, and mixtures thereof; at least one compound I selected from the group consisting of allylsulfonic acid, methallylsulfonic acid, allyldisulfonic acid, methallyldisulfonic acid, salts thereof and mixtures thereof; At least one compound II having the formula (1): 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 does not contain anionic monomers other than compound I; b) subjecting part F1 to polymerization 1 (PO1) 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 (PO3) to form a solution comprising the base polymer; g) diluting the solution containing the base polymer and subjecting the base polymer to a Hofmann degradation reaction to obtain a polyvinylamine polymer.

9. The method according to claim 8, characterized in that At least one of the parts F1, F2 or F3 is different from the other parts.

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

11. The method according to any one of claims 8 to 10, characterized in that After step f) of polymerizing (PO3) and before step g), the process comprises an aging step for 10 to 100 minutes.

12. The method according to any one of claims 8 to 11, characterized in that The Hofmann degradation reaction comprises at least the following steps: g1) diluting a solution comprising a base polymer so as to obtain a diluted solution of the base polymer (SD1); g2) adding an alkali metal hypohalite or alkaline earth metal hypohalite and an alkali metal hydroxide or alkaline earth metal hydroxide to obtain a diluted solution (SD2); g3) carrying out a reaction between a base polymer, an alkali metal hypohalite or an alkaline earth metal hypohalite and an alkali metal hydroxide or an alkaline earth metal hydroxide; g4) obtaining a solution (SD3) comprising a polyvinylamine polymer.

13. A method for producing paper or paperboard, comprising: The polyvinylamine polymer according to any one of claims 1 to 7 is added to an aqueous suspension of fibers and formed into paper or paperboard.

14. Use of the polyvinylamine polymer 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 the treatment of water in open, closed or semi-closed cycles; in the treatment of fermentation mash; in the treatment of sludge; in construction; in wood processing; in the treatment of hydraulic compositions; in the mining industry; in the formulation of cosmetics; in the formulation of detergents; in the manufacture of textiles; in the geothermal field; in the manufacture of sanitary napkins; or in agriculture.

15. Use of a polyvinylamine polymer according to any one of claims 1 to 7 as a flocculant, coagulant, binder, fixative, viscosity reducer, thickener, absorbent, friction reducer, drainage agent, charge retention agent, dehydrating agent, conditioner, stabilizer, fixative, film former, sizing agent, superplasticizer, clay inhibitor or dispersant.

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