High molecular weight polymer dispersions comprising homopolymer dispersants made by controlled polymerization

Abstract

The invention relates to a method for producing a polymeric dispersant for a water-in-water dispersion, said polymeric dispersant being water-soluble, produced by polymerizing a monomer composition comprising at least one (meth) acrylic monomer, and consuming the residual monomer after the polymerization step by adding an initiator, characterized in that the monomer composition contains at least one (meth) acrylic monomer and the initiator is added to the (meth) acrylic monomer. The step of adding the initiator is carried out at a limited temperature. Furthermore, the invention relates to a polymeric dispersant obtained by the method according to the invention. Further, the invention relates to a process for preparing a polymer dispersion comprising the steps of: providing a reaction mixture comprising a polymeric dispersant according to the invention and a monomer composition comprising a radically polymerizable monomer in an aqueous medium; and subjecting the monomer composition in the reaction mixture to free radical polymerization to synthesize a dispersed polymer, thereby forming a polymer dispersion. These polymer dispersions are referred to as water-in-water (w / w) polymer dispersions.

Description

[0001] This invention relates to a method for preparing a water-in-water dispersion of a polymeric dispersant, said polymeric dispersant being water-soluble, and is prepared by the following steps: polymerizing a monomeric composition comprising at least one (meth)acrylic acid monomer, and consuming the residual monomer by adding an initiator after the polymerization step, characterized in that the initiator addition step is carried out at a defined temperature. Furthermore, this invention relates to a polymeric dispersant obtained by the method according to the invention. Further, this invention relates to a method for preparing a polymeric dispersion comprising the steps of: providing a reaction mixture in an aqueous medium, said reaction mixture comprising the polymeric dispersant according to the invention and a monomeric composition comprising a free-radical polymerizable monomer; and subjecting said monomeric composition in said reaction mixture to free-radical polymerization to synthesize a dispersed polymer, thereby forming a polymeric dispersion. These polymeric dispersions are referred to as water-in-water (w / w) polymeric dispersions.

[0002] The primary objective is to unlock the potential of water and renewable resources to build a safer, healthier, and more sustainable world. Countless industrial processes are water-based. Replacing or reducing the use of environmentally harmful substances in water-based processes is fundamental to achieving more sustainable solutions. This invention aims to achieve this primary objective in the field of water-in-water polymer dispersions (w / w polymer dispersions). Improvements in water-in-water polymer dispersions are directly related to the sustainability of downstream applications, such as papermaking processes. The better such water-in-water polymer dispersions perform as additives in water-based processes (such as papermaking), the less additive is needed in these processes. Furthermore, the substitution of hydrocarbons also supports this primary objective.

[0003] Besides applications in other technological fields, water-in-water polymer dispersions can be used as flocculants, dewatering (filtration) aids, and retention aids in papermaking. Papermaking begins with the preparation of an aqueous pulp of cellulose fibers with a water content greater than 95% by weight. The final paper has a water content of less than 5% by weight. Dewatering (filtration) and retention are key steps in papermaking and are essential for an efficient papermaking process. High-performance water-in-water polymer dispersions are a critical factor in the papermaking process.

[0004] Existing polymer dispersions are typically stabilized using low molecular weight salts. An alternative is the use of water-in-water polymer dispersions, prepared by copolymerizing an olefinic unsaturated monomer in an aqueous system containing a polymer dispersant, resulting in a dispersion comprising the polymer dispersant and a synthesized copolymer. US8476391B2 and US7323510B2 are early publications of this type of water-in-water polymer dispersion. It is known in the art that products obtained by mixing separately synthesized copolymers and polymer dispersants have entirely different properties compared to the water-in-water polymer dispersions disclosed in the aforementioned patent documents. To obtain, for example, high-performance flocculant products for use in papermaking processes, copolymerization is required within a system containing a polymer dispersant.

[0005] These factors make the preparation of water-in-water polymer dispersions a multi-parameter system. The types of olefinic unsaturated monomers, their proportions, and the molecular weight of the polymer dispersant are only a small subset of parameters affecting the properties of water-in-water polymer dispersions. Improving the performance of the final product from water-in-water polymer dispersions has been the subject of countless research and development attempts.

[0006] One of the parameters that plays a decisive role in beneficially influencing the properties of water-in-water dispersions is the polymeric dispersant, which is a polymer other than a copolymer polymerized in the water-in-water dispersion in the presence of the polymeric dispersant.

[0007] There remains a need for improved polymer dispersant intermediates that can have beneficial effects on complex polymer systems and offer the potential to improve their properties. For example, there is still a need to improve long-term stability and ensure longer shelf life under adverse conditions such as alternating temperature changes.

[0008] Furthermore, challenges have been identified in the preparation process of the water-in-water polymer dispersions themselves. Some batches have been observed to exhibit instability during preparation. Some dispersions begin to gel during preparation. Additionally, some products exhibit instability at some point after the preparation process is complete. For example, alternating temperature changes during shipping to customers can exacerbate this instability.

[0009] The fundamental problem of this invention relates to overcoming the shortcomings of the prior art. In particular, the fundamental problem of this invention relates to providing a polymer dispersant that imparts beneficial properties to water-in-water dispersions, especially regarding the stability, long-term stability, and workability of the water-in-water dispersions, particularly concerning the viscosity of the water-in-water dispersions. Furthermore, the fundamental problem of this invention relates to providing a method for preparing water-in-water polymer dispersions that yields a product that ensures improved performance during use (especially in papermaking processes). Additionally, the fundamental problem of this invention relates to providing a method for preparing water-in-water polymer dispersions that ensures high stability during preparation and a long shelf life under adverse environments (such as alternating temperature changes).

[0010] The fundamental problem of the present invention is solved by the subject matter of claim 1. Therefore, according to a first aspect, the present invention relates to a method for preparing a polymeric dispersant for a water-in-water dispersion, said polymeric dispersant being water-soluble, prepared by the following steps: polymerizing a monomeric composition comprising at least a monomer of formula Ia. (Ia), where R 1 Indicates hydrogen or methyl; Z1 is O, NH, or NR4, where R4 represents a C1-C4-alkyl group, and Y is one of the following groups: ,in Y0 and Y1 are C1-C6 alkylene groups, optionally substituted with one or more hydroxyl groups; Y2, Y3, Y5, Y6, and Y7 are each independently a C1-C6 alkyl group; and Z - It is a counter ion; and The residual monomer is consumed by adding an initiator after the polymerization step, wherein the initiator addition step is carried out at a temperature of 80°C or higher.

[0011] The term "initiator" has a conventional meaning in the field of organic chemistry, particularly polymer chemistry. That is, an initiator is a substance added to a reaction mixture to achieve and initiate the desired reaction. In this invention, the polymerization of the monomer components is carried out in the first step. This first step is the polymerization step of the monomer components. After the first step, the residual monomers of the monomer composition are consumed. This is done by adding an initiator. Crucially, the step of consuming the residual monomers is carried out at a temperature of 80°C or higher. As for the beneficial effects, it has been surprisingly found that the subsequent method for preparing water-in-water polymer dispersions can be carried out reliably without the risk of a sharp increase in viscosity. The polymerization reaction in the first step produces a certain amount of unreacted monomer residues. The growing chains terminate before all monomers are converted. If the consumption of residual monomers is carried out with an initiator at a temperature below 80°C, it has been found that in some cases, the polymer dispersion in the process of preparing water-in-water polymer dispersions begins to gel. If the polymer dispersion is prepared according to the method of the invention, this gelation can be prevented.

[0012] According to a preferred embodiment, the step of adding the initiator is performed at a temperature above 80°C and below 90°C, preferably above 81°C and below 85°C. These temperature ranges provide an advantageous solution for the objectives of the invention in the aforementioned sense. In the prior art, it was previously thought that the temperature only needed to be below a certain level. For technical reasons, this indicates that the aforementioned temperature range has the effect described herein on the resulting product.

[0013] In a preferred embodiment, the step of adding the initiator occurs from the time the maximum temperature T is reached. max The time interval after the specified time point is within a range of 1 minute to 150 minutes, more preferably within a range of 20 minutes to 120 minutes, and even more preferably within a range of 30 minutes to 90 minutes. Maximum temperature T max It was measured within the reaction mixture.

[0014] According to a preferred embodiment, the initiator is a free radical initiator. More preferably, the free radical initiator is a water-soluble free radical initiator. Even more preferably, the free radical initiator is selected from 2,2'-azobis(2-amidinylpropane) dihydrochloride, 4,4'-azobis(4-cyanopentanoic acid), 2,2'-azobis(2-(2-imidazolin-2-yl)propane) dihydrochloride, and mixtures thereof.

[0015] According to one alternative embodiment, the initiator is a system, such as ammonium persulfate / ferric sulfate. According to another alternative embodiment, the initiator is an oil-soluble initiator; more preferably, the initiator is represented by benzoyl peroxide, dilauryl peroxide, or tert-butyl peroxide, or an azo compound such as 2,2'-azobisisobutyronitrile, dimethyl 2,2'-azobis(4-methoxy-2,4-dimethylpentanonitrile). Preferred azo compounds are 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-(2-imidazolin-2-yl)propane) dihydrochloride, and 2,2'-azobis(2-aminopropane) dihydrochloride; or, the free radical initiator is preferably potassium persulfate, ammonium persulfate, or hydrogen peroxide, optionally in combination with a reducing agent (e.g., an amine or sodium sulfite). The initiator can be used alone or in combination. However, the water-soluble free radical initiators disclosed above are preferred over these alternative initiators.

[0016] According to a preferred embodiment, the monomer composition further comprises (meth)acrylic acid and / or (meth)acrylamide. In this case, the polymer dispersant is a copolymer composed of a monomer component based on formula Ia monomer and (meth)acrylic acid and / or (meth)acrylamide monomers.

[0017] According to a preferred embodiment, the monomer composition comprises a cationic monomer belonging to formula Ia. According to a more preferred embodiment, the monomer composition comprises at least one monomer of formula Ia, wherein Z1 is O, NH, or NR4, preferably NH or NR4, wherein R4 represents methyl; Y is... ,in Y1 is ethylene or propylene, optionally substituted with a hydroxyl group; Y5, Y6, and Y7 are each methyl; and Z - It is selected from halogens, halogen-like substances, acetate, and SO4CH3. - Counterions.

[0018] The fundamental problem of the present invention is also solved by the subject matter of claim 6. Therefore, according to a second aspect, the present invention relates to polymer dispersants obtained by the method according to the invention.

[0019] Those skilled in the art will understand that the method according to the invention leaves a "structural fingerprint" on the polymer dispersant. In other words, polymer dispersants prepared by methods different from those of the present invention will produce polymer dispersant compositions different from those of the present invention. Polymer dispersants prepared according to the present invention are advantageous in methods for preparing water-in-water polymer dispersions as described herein.

[0020] According to a preferred embodiment, the polymeric dispersant has a weight-average molecular weight (Mw) of 40,000 to less than 150,000 g / mol, preferably 50,000 to 140,000 g / mol, more preferably 60,000 to 130,000 g / mol, and most preferably 85,000 to 125,000 g / mol, as determined by size exclusion chromatography.

[0021] Surprisingly, this polymer-weight polymer dispersant proved effective in preparing water-in-water polymer dispersions.

[0022] The monomer composition must contain a monomer of formula Ia above. Preferably, the monomer of formula Ia above is a cationic monomer, more preferably selected from: (alkyl)acrylamidoalkyltrialkylammonium halides (e.g., trimethylammonium-alkyl(meth)acrylamide halides), (alkyl)acryloyloxyalkyltrialkylammonium halides (e.g., trimethylammonium-alkyl(meth)acrylate halides), alkenyltrialkylammonium halides, and diallyldialkylammonium halides (e.g., diallyldialkylammonium halides). More preferably, the polymer dispersant is a cationic polymer derived from a monomer composition containing a cationic monomer selected from: trimethylammonium-alkyl(meth)acrylate halides, trimethylammonium-alkyl(meth)acrylamide halides, and diallyldialkylammonium halides. Preferably, the aforementioned cationic monomer contains 6 to 25 carbon atoms, more preferably 7 to 20 carbon atoms, most preferably 7 to 15 carbon atoms, and particularly 8 to 12 carbon atoms.

[0023] In a highly preferred embodiment, the polymer dispersant is a polymer comprising quaternized trimethylammonium-propylacrylamide (DIMAPA quaternary ammonium salt).

[0024] According to a preferred embodiment, the polymer dispersant is a cationic polymer dispersant. Particularly preferred is that the polymer dispersant is water-soluble and is prepared by polymerizing a monomer composition comprising at least one monomer from item i above, wherein Z1 is O, NH, or NR4, preferably NH or NR4, and wherein R4 represents methyl. Y is

[0025] Y1 is ethylene or propylene, optionally substituted with a hydroxyl group; Y5, Y6, and Y7 are each methyl groups; and Z - It is selected from halogens, halogen-like substances, acetate, and SO4CH3. - Counterions.

[0026] The fundamental problem of the present invention is also solved by the subject matter of claim 8. Therefore, according to a third aspect, the present invention relates to a method for preparing a water-in-water polymer dispersion, the method comprising subjecting an aqueous reaction mixture to a free radical polymerization reaction, said aqueous reaction mixture comprising (a) a polymer dispersant according to a second aspect of the present invention, and (b) a monomer composition comprising one or more of the following: i. Nonionic monomers of formula (I) ,in R 1 Indicates hydrogen or methyl; R 2 and R 3 Each of them is independently hydrogen, C1-C5-alkyl, or C1-C5-hydroxyalkyl. ii. Cationic monomers of formula (II) ,in R 1 Indicates hydrogen or methyl; Z1 is O, NH, or NR4, where R4 represents a C1-C4-alkyl group, preferably methyl, and Y is one of the following groups: ,in Y0 and Y1 are C1-C6 alkylene groups, optionally substituted with one or more hydroxyl groups, preferably ethylene or propylene, optionally substituted with one hydroxyl group; Y2, Y3, Y5, Y6, and Y7 are each independently a C1-C6-alkyl group, preferably methyl; and Z - It is a counterion, preferably a halogen, a halogen-like ion, an acetate ion, or SO4CH3. - ;and iii. Amphiphilic monomers of formula (III) or (IV) ,in Z1 is O, NH, or NR4, where R4 represents a C1-C4-alkyl group, preferably methyl. R1 represents hydrogen or methyl. R8 is a C1-C6 alkylene group, preferably ethylene or propylene. R5 and R6 are each independently C1-C6-alkyl, preferably methyl. R7 is C8-C 32 Alkyl groups, optionally substituted with one or more hydroxyl groups, preferably C10. 12 -C 20 Alkyl group, optionally substituted with a hydroxyl group, and Z -It is a counterion, preferably a halogen, a halogen-like ion, an acetate ion, or SO4CH3. - ;or ,in Z1 is O, NH, or NR4, where R4 represents a C1-C4-alkyl group, preferably methyl. R1 represents hydrogen or methyl. R 10 Indicates hydrogen, C8-C 32 Alkyl, C8-C 32 Aryl and / or C8-C 32 Aryl alkyl group, preferably C 12 -C 20 alkyl, R9 is a C1-C6 alkylene group, preferably ethylene or propylene. n is an integer from 1 to 50, preferably from 2 to 30, more preferably from 3 to 15, and most preferably from 4 to 8; and iv. An olefinically unsaturated crosslinking agent containing 2, 3, 4 or 5 olefinically unsaturated groups.

[0027] This method according to the third aspect of the invention yields a water-in-water polymer dispersion. Surprisingly, it was found that the method can be carried out reliably without an undesirable sharp increase in viscosity due to gelation of the reactive composition.

[0028] The method includes providing a reaction mixture comprising a monomer to be copolymerized and a polymeric dispersant according to the first aspect. The monomer is polymerized in an aqueous medium in the presence of the polymeric dispersant. It should be noted that the term "monomer composition" is different from the term "monomer group". "Monomer composition" is used to obtain a polymeric dispersant, while "monomer group" produces a copolymer present in a water-in-water dispersion. According to known technical knowledge, it is impossible to obtain the polymeric dispersion obtained by the method of the second aspect of the invention by copolymerizing the monomer composition and then adding the polymeric dispersant after the copolymerization reaction. By applying the method of the invention, the polymeric dispersion is endowed with unique properties, representing a final product comprising a copolymer obtained from a free radical polymerizable monomer and a polymeric dispersant.

[0029] Within the framework of this invention, a cationic monomer is a monomer that is permanently positively charged.

[0030] According to a preferred embodiment, one or more monomers given in items i. to iv. above are used as monomers in the monomer composition to be polymerized. Preferably, a copolymer is used, i.e., the monomer composition to be polymerized provides two monomers given in items i. to iv. above. Preferably, the monomer composition undergoing the copolymerization reaction provides a monomer of item i. and a monomer of item ii. In a preferred embodiment, the radical-polymerizable monomer comprises a radical-polymerizable nonionic monomer according to general formula (I); and a radical-polymerizable cationic monomer according to general formula (II). These copolymerized monomers are advantageous for solving the aforementioned problems.

[0031] According to a preferred embodiment, the monomer composition comprises at least a nonionic monomer of formula (I) and a cationic monomer of formula (II). More preferably, the nonionic monomer of formula (I) is acrylamide.

[0032] Furthermore, the monomer composition for copolymerization preferably provides a monomer of item i, a monomer of item ii, and a monomer of item iv.

[0033] In a preferred embodiment, the method is characterized in that the monomer composition comprising a free radical polymerizable monomer comprises at least a nonionic monomer selected from formula (I) of the following: wherein R 1 R represents hydrogen or methyl. 2 and R 3 All are hydrogen, hydrogen and C1-C3 alkyl, hydrogen and hydroxyethyl, or all are C1-C3 alkyl, and / or selected from the following formula (II) cationic monomers: wherein R¹ represents hydrogen or methyl, Z1 is O, NH or NR4, wherein R4 represents methyl, Y1 is C2-C6 alkylene, preferably ethylene or propylene, Y5, Y6 and Y7 are all methyl, and Z - It is halogen.

[0034] In a preferred embodiment, the radical-polymerizable monomer comprises a radical-polymerizable nonionic monomer according to general formula (I), selected from: (meth)acrylamide, N-methyl(meth)acrylamide, N,N'-dimethyl(meth)acrylamide, N-ethyl(meth)acrylamide, N,N'-diethyl(meth)acrylamide, N-methyl-N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, and N-hydroxyethyl(meth)acrylamide.

[0035] In another preferred embodiment, the radical-polymerizable monomer comprises a radical-polymerizable cationic monomer according to general formula (II), selected from: trimethylammonium-C2-C6-alkyl (meth)acrylate halides and trimethylammonium-C2-C6-alkyl (meth)acrylamide halides. In a most preferred embodiment, the monomer composition comprises (meth)acrylamide as a radical-polymerizable monomer and a radical-polymerizable monomer selected from trimethylammonium-C2-C6-alkyl (meth)acrylate halides, particularly acryloyloxyethyltrimethylammonium halides.

[0036] Within the framework of this application, the terms "halogen" or "halogen" can be any acceptable halogen or halide, such as chloride, bromide, or iodide; the counter ion of the salt can be any acceptable counter ion, such as halide ion, methylsulfate, sulfate, or others.

[0037] According to one embodiment, the monomer composition comprising a free radical polymerizable monomer includes a crosslinking agent. Crosslinking agents are known to those skilled in the art. In this preferred embodiment, the monomer composition preferably contains 0.0001 to 1.25% by weight of one or more preferred olefin unsaturated crosslinking agents based on the total weight of the monomers. If olefin unsaturated crosslinking agents are present, they contain 2, 3, 4, or 5 free radical polymerizable olefin unsaturated groups.

[0038] Examples of crosslinking agents having two free radical polymerizable olefinic unsaturated groups include: (1) Alkenyl di(meth)acrylates, such as 1,6-hexanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, 1,18-octadecanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, methylene di(meth)acrylate, 2,2'-bis(hydroxymethyl)-1,3-propanediol di(meth)acrylate, and preferably, ethylene glycol di(meth)acrylate, 1,3-propanediol di(meth)acrylate, 1,3-butanediol di(meth)acrylate and 1,4-butanediol di(meth)acrylate; (2) Alkylene di(meth)acrylamide, such as N-methylene di(meth)acrylamide, N,N'-3-methyl-butylene bis(meth)acrylamide, N,N'-(1,2-dihydroxyethylene)bis(meth)acrylamide, and preferably, N,N'-hexamethylene bis(meth)acrylamide, and particularly preferably, N,N'-methylene bis(meth)acrylamide; (3) Polyalkoxydi(meth)acrylates according to general formula (V) (V), in R 10 It is hydrogen or methyl; R 11 Selected from -CH2CH2-, -CH2CH2CH2-, -CH2CH2CH2CH2-, -CH2CH2CH2CH2CH2- or -CH2CH2CH2CH2CH2CH2-; and m is an integer in the range of 2-50.

[0039] Examples of crosslinking agents according to general formula (V) include polypropylene glycol di(meth)acrylate with m ranging from 4 to 25; polybutylene glycol di(meth)acrylate with m ranging from 5 to 40; and preferably, polyethylene glycol di(meth)acrylate with m ranging from 2 to 45, such as diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate; and more preferably, polyethylene glycol di(meth)acrylate with m ranging from 5 to 20. (4) Other examples of di(meth)acrylates that may be used include benzyl di(meth)acrylate, bisphenol A di(meth)acrylate, 1,3-di(meth)acryloyloxy-2-propanol, hydroquinone di(meth)acrylate, ethylene dithiol di(meth)acrylate, propylene dithiol di(meth)acrylate, polyethylene dithiol di(meth)acrylate and polypropylene dithiol di(meth)acrylate; (5) Divinyl compounds, such as 1,4-butanediol divinyl ether, divinylbenzene, butadiene, 1,6-hexadiene; di(meth)allyl compounds, such as di(meth)allyl phthalate or di(meth)allyl succinate; vinyl(meth)acrylic acid compounds, such as vinyl(meth)acrylate; or preferably (meth)allyl(meth)acrylic acid compounds, such as allyl(meth)acrylate.

[0040] Examples of crosslinking agents having three or more olefinically unsaturated free radical polymerizable groups include glycerol tri(meth)acrylate, 2,2-dimethylol-1-butanol tri(meth)acrylate, trimethylolpropane triethoxytri(meth)acrylate, trimethacrylamide, (meth)allylide di(meth)acrylate, 3-allyloxy-1,2-propanediol di(meth)acrylate, triallylamine, triallyl cyanurate, or triallyl isocyanurate; and also (as representative compounds having more than three olefinically unsaturated free radical polymerizable groups) pentaerythritol tetra(meth)acrylate and N,N,N',N'-tetra(meth)acryloyl-1,5-pentanediamine.

[0041] An example of a crosslinking agent having five olefinically unsaturated free radical polymerizable groups is dipentaerythritol pentaacrylate.

[0042] The preferred crosslinking agent is selected from methylenebisacrylamide, polyethylene glycol diacrylate and triallylamine.

[0043] Further preferred crosslinking agents include asymmetric crosslinkable monomers, i.e., crosslinkable monomers that rely on different functional groups for main chain introduction and crosslinking reactions. Examples of such asymmetric crosslinkable monomers include N'-hydroxymethylacrylamide, N'-hydroxymethylmethacrylamide, and glycidyl (meth)acrylate.

[0044] The advantage of this type of crosslinking agent is that it can subsequently initiate crosslinking. Therefore, crosslinking can occur under conditions different from those of main-chain free radical polymerization. Preferably, crosslinking is initiated after changing the reaction conditions, such as pH (addition of acid or alkali), temperature, etc. Optionally, the monomer composition also comprises a hydrophobic monomer, preferably a hydrophobic (meth)acrylic acid C4- 18 -Alkyl esters; and / or olefinic unsaturated monomers.

[0045] In a preferred embodiment, the method is characterized in that the free radical polymerizable monomer is selected from nonionic monomers of formula (I) and / or cationic monomers of formula (II), wherein, based on the total amount of free radical polymerizable monomers, the amount of free radical polymerizable monomers selected from nonionic monomers of formula (I) and / or cationic monomers of formula (II) is 80 to less than 100 wt%, preferably 85 to 99 wt%, most preferably 90 to 95 wt%, and the balance is selected from any other olefin polymerizable monomers, monomers of formula (III), monomers of formula (IV), and olefin unsaturated crosslinking agents containing 2, 3, 4, or 5 olefin unsaturated groups.

[0046] In this regard, the sum of the values ​​expressed as % by weight need not reach 100% by weight, because in addition to the monomers of formula (I) and / or (II), the monomer composition (i.e., the reaction mixture) may contain other olefinically unsaturated monomers, which must be taken into account when determining the total amount of monomers. However, in a preferred embodiment, the monomer composition consists of (a) and (b), so the sum of the two % by weight values ​​is 100% by weight, meaning that no other monomers are present.

[0047] In a preferred embodiment, the monomer composition comprises: At least 5% by weight, preferably at least 20% by weight, of the nonionic monomer of formula (I). ,in R¹ represents hydrogen or methyl; R² and R³ are independently hydrogen, C1-C5-alkyl, or C1-C5-hydroxyalkyl; At least 5% by weight, preferably at least 20% by weight, more preferably 25 to 47% by weight, and most preferably 50.5 to 80% by weight of the cationic monomer of formula (II). ,in R¹ represents hydrogen or methyl; Z1 is O, NH, or NR4, where R4 represents a C1-C4-alkyl group, preferably methyl, and Y is one of the following groups: ,in Y0 and Y1 are C1-C6 alkylene groups, optionally substituted with one or more hydroxyl groups, preferably ethylene or propylene, optionally substituted with one hydroxyl group; Y2, Y3, Y5, Y6, and Y7 are each independently a C1-C6-alkyl group, preferably methyl; and Z - It is a counterion, preferably a halogen, a halogen-like ion, an acetate ion, or SO4CH3. - ; 0.0001 to 1.25% by weight, preferably 0.0005 to 1% by weight, of an olefinically unsaturated crosslinking agent containing 2, 3, 4, or 5 olefinically unsaturated groups; and Other optional olefinic unsaturated monomers.

[0048] To reiterate in this regard, the sum of the values ​​expressed as % by weight need not reach 100% by weight, because in addition to the monomers of formula (I) and / or (II), the monomer composition (i.e., the reaction mixture) may contain other olefinically unsaturated monomers, which must be taken into account when determining the total amount of monomers. However, in a preferred embodiment, the monomer composition consists of (a) and (b), so the sum of the two % by weight values ​​is 100% by weight, meaning that no other monomers are present.

[0049] In this application, all percentages relating to monomer compositions are based on the total amount of monomers used in the copolymerization reaction. Percentages relating to monomer compositions are based on the total amount of monomers used to prepare the polymer dispersant.

[0050] In a preferred embodiment, the method is characterized in that the viscosity of the polymer dispersion is from 1,800 mPa·s to less than 6,700 mPa·s, preferably from 2,000 mPa·s to 6,000 mPa·s, more preferably from 2,200 mPa·s to 5,500 mPa·s, and most preferably from 2,500 mPa·s to 5,000 mPa·s, measured using a Brookfield viscometer with a No. 4 rotor at 20°C and an angular velocity of 10 rpm.

[0051] The viscosity is preferably the bulk viscosity, which refers to the viscosity of the product immediately after it has cooled.

[0052] According to a preferred embodiment, the ratio of polymer dispersant to dispersing polymer in the polymer dispersion is in the range of 0.45:1 to 1:0.9, preferably in the range of 0.5:1 to 1:1, more preferably in the range of 0.55:1 to less than 1:1, even more preferably in the range of 0.6:1 to 0.99:1, and particularly in the range of 0.65:1 to 0.9:1.

[0053] The invention is particularly effective if the method is characterized in that the total weight of the polymer dispersant, based on the total weight of the polymer dispersion, is in the range of 10 to 28% by weight, preferably 12 to 26% by weight, more preferably 14 to 24% by weight, and even more preferably 16 to 22% by weight.

[0054] According to another embodiment, the method is characterized in that, based on the total weight of the polymer dispersion, the total weight of the polymer dispersant is between 18 and 26% by weight, preferably between 19 and 25% by weight.

[0055] According to another preferred embodiment, the method is characterized in that the monomer composition does not contain any hydrophobic monomers.

[0056] The fundamental problem of the present invention is also solved by the subject matter of claim 12. Therefore, according to a fourth aspect, the present invention relates to a water-in-water polymer dispersion comprising: (a) A polymer dispersant according to a second aspect of the invention, and (b) A copolymer derived from a monomer composition comprising one or more of the following: i. Nonionic monomers of formula (I) ,in R 1 Indicates hydrogen or methyl; R 2 and R 3 Each of them is independently hydrogen, C1-C5-alkyl, or C1-C5-hydroxyalkyl. ii. Cationic monomers of formula (II) ,in R¹ represents hydrogen or methyl; Z1 is O, NH, or NR4, where R4 represents a C1-C4-alkyl group, preferably methyl, and Y is one of the following groups: ,in Y0 and Y1 are C1-C6 alkylene groups, optionally substituted with one or more hydroxyl groups, preferably ethylene or propylene, optionally substituted with one hydroxyl group; Y2, Y3, Y5, Y6, and Y7 are each independently a C1-C6-alkyl group, preferably methyl; and Z - It is a counterion, preferably a halogen, a halogen-like ion, an acetate ion, or SO4CH3. - ;and iii. Amphiphilic monomers of formula (III) or (IV) ,in Z1 is O, NH, or NR4, where R4 represents a C1-C4-alkyl group, preferably methyl. R1 represents hydrogen or methyl. R8 is a C1-C6 alkylene group, preferably ethylene or propylene. R5 and R6 are each independently C1-C6-alkyl, preferably methyl. R7 is C8-C 32 Alkyl groups, optionally substituted with one or more hydroxyl groups, preferably C10. 12 -C 20 Alkyl group, optionally substituted with a hydroxyl group, and Z - It is a counterion, preferably a halogen, a halogen-like ion, an acetate ion, or SO4CH3. - ;or ,in Z1 is O, NH, or NR4, where R4 represents a C1-C4-alkyl group, preferably methyl. R1 represents hydrogen or methyl. R 10 Indicates hydrogen, C8-C 32 Alkyl, C8-C 32 Aryl and / or C8-C 32 Aryl alkyl group, preferably C 12 -C 20 alkyl, R9 is a C1-C6 alkylene group, preferably ethylene or propylene, and n is an integer from 1 to 50, preferably from 2 to 30, more preferably from 3 to 15, and most preferably from 4 to 8; and iv. An olefinically unsaturated crosslinking agent containing 2, 3, 4 or 5 olefinically unsaturated groups.

[0057] According to a preferred embodiment, the polymer dispersion is obtained by a method for preparing a polymer dispersion, wherein the weight-average molecular weight Mw of the polymer dispersion is 40,000 to less than 150,000 g / mol, preferably 50,000 to 140,000 g / mol, more preferably 60,000 to 130,000 g / mol, and most preferably 85,000 to 120,000 g / mol, as determined by size exclusion chromatography.

[0058] According to a preferred embodiment, the polymer dispersion is obtained by a method for preparing a polymer dispersion, wherein the bulk viscosity of the polymer dispersion is less than 6,700 mPa·s, preferably less than 6,000 mPa·s, more preferably less than 5,500 mPa·s, and most preferably less than 5,000 mPa·s, measured at 20°C using a Brookfield viscometer, a No. 4 rotor, and a rotation speed of 10 rpm.

[0059] The fundamental problem of the present invention is also solved by the subject matter of claim 13. Therefore, according to a fifth aspect, the present invention relates to a water-in-water polymer dispersion obtained by a method according to a third aspect of the present invention.

[0060] The fundamental problem of the present invention is also solved by the subject matter of claim 14. Therefore, according to a sixth aspect, the present invention relates to the use of polymer dispersions according to the fourth and fifth aspects of the present invention in the following aspects: a. Used as a flocculant in solid sedimentation, flotation, or filtration. b. Used as a thickener c. Used as a pollutant control agent, d. Used as a dry strength agent; e. Or used as a retention aid or filter aid in papermaking.

[0061] Features relating to the preferred embodiments of the first aspect of the invention (these features are disclosed only with respect to the first aspect of the invention) also constitute features of the preferred embodiments of the second, third, fourth, fifth, and sixth aspects of the invention. Features relating to the preferred embodiments of the second aspect of the invention (these features are disclosed only with respect to the second aspect of the invention) also constitute features of the preferred embodiments of the first, third, fourth, fifth, and sixth aspects of the invention. Features relating to the preferred embodiments of the third aspect of the invention (these features are disclosed only with respect to the third aspect of the invention) also constitute features of the preferred embodiments of the first, second, fourth, fifth, and sixth aspects of the invention.

[0062] Exemplary embodiments (A) to (F) representing particularly preferred embodiments are disclosed below.

[0063] (A) A method for preparing a polymeric dispersant for a water-in-water dispersion, said polymeric dispersant being water-soluble, is prepared by the following steps: polymerizing a monomeric composition comprising at least a monomer of formula Ia. (Ia), where R 1 Indicates hydrogen or methyl; Z1 is O, NH, or NR4, where R4 represents a C1-C4-alkyl group, and Y is one of the following groups: ,in Y0 and Y1 are C1-C6 alkylene groups, optionally substituted with one or more hydroxyl groups; Y2, Y3, Y5, Y6, and Y7 are each independently a C1-C6 alkyl group; and Z - These are counterions; residual monomers are consumed by adding an initiator after the polymerization step. The characteristic feature is that the step of adding the initiator is carried out at a temperature of 80°C or higher and lower than 90°C, preferably higher than 81°C and lower than 85°C.

[0064] (B) A method for preparing a polymeric dispersant for a water-in-water dispersion, said polymeric dispersant being water-soluble, is prepared by the following steps: polymerizing a monomeric composition comprising at least a monomer of formula Ia. (Ia), where R 1 Indicates hydrogen or methyl; Z1 is O, NH, or NR4, where R4 represents a C1-C4-alkyl group, and Y is one of the following groups: ,in Y0 and Y1 are C1-C6 alkylene groups, optionally substituted with one or more hydroxyl groups; Y2, Y3, Y5, Y6, and Y7 are each independently a C1-C6 alkyl group; and Z - These are counterions; residual monomers are consumed by adding an initiator after the polymerization step. The characteristic feature is that the step of adding the initiator is carried out at a temperature of 80°C or higher and lower than 90°C, preferably higher than 81°C and lower than 85°C, wherein the step of adding the initiator is carried out within a time range of 0 seconds to 60 minutes after the time point of reaching the maximum temperature Tmax, more preferably within a time range of 1 minute to 30 minutes, and even more preferably within a time range of 5 minutes to 15 minutes.

[0065] (C) A method for preparing a polymeric dispersant for a water-in-water dispersion, said polymeric dispersant being water-soluble, is prepared by the following steps: polymerizing a monomeric composition comprising at least a monomer of formula Ia. (Ia), where R¹ represents hydrogen or methyl; Z1 is O, NH, or NR4, where R4 represents a C1-C4-alkyl group, and Y is one of the following groups: ,in Y0 and Y1 are C1-C6 alkylene groups, optionally substituted with one or more hydroxyl groups; Y2, Y3, Y5, Y6, and Y7 are each independently a C1-C6 alkyl group; and Z - These are counterions; residual monomers are consumed by adding an initiator after the polymerization step. The characteristic feature is that the step of adding the initiator is carried out at a temperature of 80°C or higher and lower than 85°C, wherein the initiator is a free radical initiator, preferably 2,2'-azobis(2-amidinylpropane) dihydrochloride, 4,4'-azobis(4-cyanopentanoic acid), 2,2'-azobis(2-(2-imidazolin-2-yl)propane) dihydrochloride and mixtures thereof, especially 2,2'-azobis(2-amidinylpropane) dihydrochloride.

[0066] (D) A method for preparing a water-in-water dispersion of a polymeric dispersant, said polymeric dispersant being water-soluble, comprising the following steps: polymerizing a monomeric composition comprising at least one (meth)acryloylaminopropyltrimethylammonium salt or (meth)acryloyloxyethyltrimethylammonium salt; and consuming the residual monomers by adding an initiator after the polymerization step. The step of adding the initiator is carried out at a temperature above 80°C and below 85°C.

[0067] (E) A method for preparing a water-in-water polymer dispersion, the method comprising subjecting an aqueous reaction mixture to a free radical polymerization reaction, the aqueous reaction mixture comprising: (a) A polymeric dispersant prepared by a method for preparing a water-in-water dispersion, said polymeric dispersant being water-soluble, and prepared by the following steps: polymerizing a monomeric composition comprising at least a monomer of formula Ia. (Ia), where R¹ represents hydrogen or methyl; Z1 is O, NH, or NR4, where R4 represents a C1-C4-alkyl group, and Y is one of the following groups: ,in Y0 and Y1 are C1-C6 alkylene groups, optionally substituted with one or more hydroxyl groups; Y2, Y3, Y5, Y6, and Y7 are each independently a C1-C6 alkyl group; and Z - These are counterions; residual monomers are consumed by adding an initiator after the polymerization step. The step of adding the initiator is carried out at a temperature of 80°C or higher but lower than 90°C, preferably higher than 81°C but lower than 85°C. (b) A composition comprising one or more of the following monomers: i. Nonionic monomers of formula (I) ,in R 1 Indicates hydrogen or methyl; R 2 and R 3 Each of them is independently hydrogen, C1-C5-alkyl, or C1-C5-hydroxyalkyl. ii. Cationic monomers of formula (II) ,in R 1 Indicates hydrogen or methyl; Z1 is O, NH, or NR4, where R4 represents a C1-C4-alkyl group, preferably methyl, and Y is one of the following groups: ,in Y0 and Y1 are C1-C6 alkylene groups, optionally substituted with one or more hydroxyl groups, preferably ethylene or propylene, optionally substituted with one hydroxyl group; Y2, Y3, Y5, Y6, and Y7 are each independently a C1-C6-alkyl group, preferably methyl; and Z - It is a counterion, preferably a halogen, a halogen-like ion, an acetate ion, or SO4CH3. -;and iv. An olefinically unsaturated crosslinking agent containing 2, 3, 4 or 5 olefinically unsaturated groups.

[0068] (F) A method for preparing a water-in-water polymer dispersion, the method comprising subjecting an aqueous reaction mixture to a free radical polymerization reaction, the aqueous reaction mixture comprising: (a) A polymeric dispersant prepared by a method for preparing a water-in-water dispersion, said polymeric dispersant being water-soluble, and prepared by the following steps: polymerizing a monomeric composition comprising at least one (meth)acryloylaminopropyltrimethylammonium salt or (meth)acryloyloxyethyltrimethylammonium salt; and consuming the residual monomers after the polymerization step by adding an initiator, said initiator preferably a free radical initiator, most preferably 2,2'-azobis(2-amidinylpropane) dihydrochloride. The step of adding the initiator is carried out at a temperature of 80°C or higher and 85°C or lower; and (b) A monomer composition comprising a radically polymerizable nonionic monomer according to general formula (I), said nonionic monomer being selected from: (meth)acrylamide, N-methyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-ethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-methyl-N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, and N-hydroxyethyl(meth)acrylamide; and / or a radically polymerizable cationic monomer according to general formula (II), said cationic monomer being selected from: trimethylammonium-C2-C6-alkyl(meth)acrylate halides and trimethylammonium-C2-C6-alkyl(meth)acrylamide halides. In a most preferred embodiment, the monomer composition comprises (meth)acrylamide as a radically polymerizable monomer and a radically polymerizable monomer selected from trimethylammonium-C2-C6-alkyl(meth)acrylate halides, particularly acryloyloxyethyltrimethylammonium halides.

[0069] Example The testing methods used are described in detail below: Bulk viscosity measurements are as follows: Use the product directly for measurement. Slowly immerse rotor #4 into the product and measure the viscosity using a Brookfield RVT viscometer at 10 rpm. Stop the measurement when the reading remains constant for 30 seconds.

[0070] Molecular weight measurements are as follows: Molar mass is measured by size exclusion chromatography (SEC). This measurement is particularly useful for determining the molecular weight of dispersants.

[0071] Molecular weight was characterized using an aqueous SEC calibrated with Pullulan standards.

[0072] Sample preparation: The sample was diluted with eluent (the polymer was dissolved in a volumetric flask) and filtered through a 1µm filter cartridge (M&N) (using a syringe) before injection.

[0073] If the instrument is equipped with an autosampler filter, the solution is filtered into a vial through a 1µm filter cartridge.

[0074] Parameters used: Instrument: SEC (Agilent) Column: Novema 3000 (PSS) Detector: RI Eluent: 1.5 wt% formic acid aqueous solution Flow rate: 1 ml / min Calibration standards: Pullland of different Mw The following embodiments further illustrate the present invention, but should not be construed as limiting its scope.

[0075] Example 1: Synthesis of Polymer Dispersants First, 294.06 g of water, 666.7 g of acrylamidopropyltrimethylammonium chloride (DIMAPA quaternary ammonium salt) (60 wt%), and sulfuric acid (50 wt%) were weighed into a 2 L container to adjust the pH to 5.0 ± 0.2. Then, the monomer solution was purged with nitrogen for 30 minutes with stirring. Subsequently, the aqueous solution was heated to 65°C, and quaternized N-[3-(dimethylamino)propyl]-3-{[3-(dimethylamino)propyl](2-{[3-(dimethylamino)propyl]carbamoyl}ethyl)amino}acrylamide and V-50 (2,2'-azobis(2-amidinylpropane)dihydrochloride) were added to the solution. The pH was adjusted to T... max Then, cool the container to 80°C. Next, add the additional initiator (V-50) to the product in two portions over 10 minutes to consume any remaining monomer. Stir the product at 70°C for 1 hour. Cool the final aqueous product to 30°C. The dispersant is provided as a 40% by weight aqueous solution.

[0076] Example 2: Synthesis of polymer dispersion (charge density 15 mol%) In a batch process (batch size 1,000 kg), acrylamide and acryloyloxyethyltrimethylammonium chloride (ADAME quaternary ammonium salt) were polymerized in an aqueous solution in the presence of acrylamidopropyltrimethylammonium chloride (the polymer dispersant of Example 1). The aqueous phase was prepared at 200 rpm.

[0077] First, 206.90 kg of soft water, 261.80 kg of bio-based acrylamide (49 wt%), 77.20 kg of acryloyloxyethyltrimethylammonium chloride (ADAME quaternary ammonium salt) (80 wt%), 412.50 kg of the polymer dispersant from Example 1, 10.00 kg of ammonium sulfate, and 0.20 kg of Trilon C were added to the reaction vessel. The pH was adjusted to pH 5.0 ± 0.2 with approximately 0.10 kg of sulfuric acid (50%). The vessel was evacuated five times before being purged with nitrogen. The initiator composition was added under a negative pressure of 0.5 bar and at maximum stirrer speed. Initiation was started at 22±1°C by adding 0.34 kg of V-50 dissolved in 3.05 kg of soft water, 0.025 kg of sodium persulfate dissolved in 0.47 kg of soft water, 0.014 kg of sodium bisulfite dissolved in 0.27 kg of soft water, and 0.003 kg of tert-butyl hydroperoxide (70%) dissolved in 1 kg of soft water. The container was then purged with nitrogen again. After reaching the maximum temperature, 0.17 kg of V-50 solution dissolved in 1.53 kg of soft water was added to reduce the monomer content. After a one-hour post-reaction time, the product was cooled to below 40°C. Then, 8.30 kg of citric acid and 0.82 kg of the fungicide Acticide SPX were added, and the product was cooled to below 30°C.

[0078] Water-in-water polymer dispersions 1 and 2 were prepared on a laboratory scale: In the first example, the elimination of additional monomers (i.e., post-elimination (burnout)) was carried out at 60°C. In the second example, this post-elimination was carried out at 80°C. With energy initiation via stirring, the viscosity in the first example increased sharply, i.e., when the post-elimination temperature was below 80°C. Even without initiation via energy input, the viscosity increased over time.

[0079]

[0080] Plant-scale examples show the same effect: if the post-elimination temperature is below 80°C, as shown in batches 2837092, 2839857, 2823287, 2840486, 2840334, and 2839862, the viscosity increases. If initiated by energy input, the rate of viscosity increase is even higher. If the post-elimination temperature reaches 80°C, the product is stable, as indicated by the constant viscosity over time.

[0081]

Claims

1. A method for preparing a polymeric dispersant for use in water-in-water dispersions, wherein the polymeric dispersant is water-soluble and is prepared by the following steps: - A monomer composition comprising at least one monomer of formula Ia. (Ia), where R¹ represents hydrogen or methyl; Z1 is O, NH, or NR4, where R4 represents a C1-C4-alkyl group, and Y is one of the following groups: ,in Y0 and Y1 are C1-C6 alkylene groups, optionally substituted with one or more hydroxyl groups; Y2, Y3, Y5, Y6, and Y7 are each independently a C1-C6 alkyl group; and Z - It is a counter ion; - Residual monomers are consumed by adding an initiator after the polymerization step. Its features are, The initiator addition step is carried out at 80°C or higher.

2. The method according to claim 1, characterized in that, The step of adding the initiator is carried out at a temperature above 80°C and below 90°C, preferably above 81°C and below 85°C.

3. The method according to claim 1 or 2, characterized in that, The initiator is a free radical initiator, preferably 2,2'-azobis(2-amidinylpropane) dihydrochloride, 4,4'-azobis(4-cyanopentanoic acid), 2,2'-azobis(2-(2-imidazolin-2-yl)propane) dihydrochloride and mixtures thereof, especially 2,2'-azobis(2-amidinylpropane) dihydrochloride.

4. The method according to any one of claims 1 to 3, characterized in that, The monomer composition also contains (meth)acrylic acid and / or (meth)acrylamide.

5. The method according to any one of claims 1 to 4, characterized in that, The monomer composition comprises a cationic monomer belonging to formula Ia, preferably characterized in that, The monomer composition comprises at least one monomer of formula Ia, wherein Z1 is O, NH or NR4, preferably NH or NR4, wherein R4 represents methyl; Y is ; Y1 is ethylene or propylene, optionally substituted with a hydroxyl group; Y5, Y6, and Y7 are each methyl groups; and Z... - It is selected from halogens, halogen-like substances, acetate, and SO4CH3. - Counterions.

6. A polymeric dispersant, obtained by the method according to any one of claims 1 to 5.

7. The polymer dispersant according to claim 6, characterized in that, The polymer dispersant has a weight-average molecular weight (Mw) of 40,000 to less than 150,000 g / mol, preferably 50,000 to 140,000 g / mol, more preferably 60,000 to 130,000 g / mol, and most preferably 85,000 to 125,000 g / mol, as determined by size exclusion chromatography.

8. A method for preparing a water-in-water polymer dispersion, the method comprising subjecting an aqueous reaction mixture to a free radical polymerization reaction, said aqueous reaction mixture comprising: (a) The polymer dispersant according to claim 6 or 7, and (b) A composition comprising one or more of the following monomers i. Nonionic monomers of formula (I) ,in R 1 Indicates hydrogen or methyl; R 2 and R 3 Each of them is independently hydrogen, C1-C5-alkyl, or C1-C5-hydroxyalkyl. ii. Cationic monomers of formula (II) ,in R¹ represents hydrogen or methyl; Z1 is O, NH, or NR4, where R4 represents a C1-C4-alkyl group, preferably methyl, and Y is one of the following groups: ,in Y0 and Y1 are C1-C6 alkylene groups, optionally substituted with one or more hydroxyl groups, preferably ethylene or propylene, optionally substituted with one hydroxyl group; Y2, Y3, Y5, Y6, and Y7 are each independently a C1-C6-alkyl group, preferably methyl; and Z - It is a counterion, preferably a halogen, a halogen-like ion, an acetate ion, or SO4CH3. - ;and iii. Amphiphilic monomers of formula (III) or (IV) ,in Z1 is O, NH, or NR4, where R4 represents a C1-C4-alkyl group, preferably methyl. R1 represents hydrogen or methyl. R8 is a C1-C6 alkylene group, preferably ethylene or propylene. R5 and R6 are each independently C1-C6-alkyl, preferably methyl. R7 is C8-C 32 Alkyl groups, optionally substituted with one or more hydroxyl groups, preferably C10. 12 -C 20 Alkyl group, optionally substituted with a hydroxyl group, and Z - It is a counterion, preferably a halogen, a halogen-like ion, an acetate ion, or SO4CH3. - ;or ,in Z1 is O, NH, or NR4, where R4 represents a C1-C4-alkyl group, preferably methyl. R1 represents hydrogen or methyl. R 10 Indicates hydrogen, C8-C 32 Alkyl, C8-C 32 Aryl and / or C8-C 32 Aryl alkyl group, preferably C 12 -C 20 alkyl, R9 is a C1-C6 alkylene group, preferably ethylene or propylene. n is an integer from 1 to 50, preferably from 2 to 30, more preferably from 3 to 15, and most preferably from 4 to 8; and iv. An olefinically unsaturated crosslinking agent containing 2, 3, 4 or 5 olefinically unsaturated groups.

9. The method according to claim 8, characterized in that, The monomer composition comprises at least a nonionic monomer of formula (I) and a cationic monomer of formula (II).

10. The method according to claim 8 or 9, characterized in that, The nonionic monomer of formula (I) is acrylamide.

11. The method according to any one of claims 8 to 10, characterized in that, The olefin unsaturated crosslinking agent containing 2, 3, 4 or 5 olefin unsaturated groups is a crosslinking agent containing 2 or 3 olefin unsaturated groups, preferably selected from methylene bisacrylamide, polyethylene glycol diacrylate and triallylamine.

12. A water-in-water polymer dispersion comprising: (a) The polymer dispersant according to claim 6 or 7, and (b) A copolymer derived from a monomer composition comprising one or more of the following: i. Nonionic monomers of formula (I) ,in R 1 Indicates hydrogen or methyl; R 2 and R 3 Each of them is independently hydrogen, C1-C5-alkyl, or C1-C5-hydroxyalkyl. ii. Cationic monomers of formula (II) ,in R 1 Indicates hydrogen or methyl; Z1 is O, NH, or NR4, where R4 represents a C1-C4-alkyl group, preferably methyl, and Y is one of the following groups: ,in Y0 and Y1 are C1-C6 alkylene groups, optionally substituted with one or more hydroxyl groups, preferably ethylene or propylene, optionally substituted with one hydroxyl group; Y2, Y3, Y5, Y6, and Y7 are each independently a C1-C6-alkyl group, preferably methyl; and Z - It is a counterion, preferably a halogen, a halogen-like ion, an acetate ion, or SO4CH3. - ;and iii. Amphiphilic monomers of formula (III) or (IV) ,in Z1 is O, NH, or NR4, where R4 represents a C1-C4-alkyl group, preferably methyl. R1 represents hydrogen or methyl. R8 is a C1-C6 alkylene group, preferably ethylene or propylene. R5 and R6 are each independently C1-C6-alkyl, preferably methyl. R7 is C8-C 32 Alkyl groups, optionally substituted with one or more hydroxyl groups, preferably C10. 12 -C 20 Alkyl group, optionally substituted with a hydroxyl group, and Z - It is a counterion, preferably a halogen, a halogen-like ion, an acetate ion, or SO4CH3. - ;or ,in Z1 is O, NH, or NR4, where R4 represents a C1-C4-alkyl group, preferably methyl. R1 represents hydrogen or methyl. R 10 Indicates hydrogen, C8-C 32 Alkyl, C8-C 32 Aryl and / or C8-C 32 Aryl alkyl group, preferably C 12 -C 20 alkyl, R9 is a C1-C6 alkylene group, preferably ethylene or propylene, and n is an integer from 1 to 50, preferably from 2 to 30, more preferably from 3 to 15, and most preferably from 4 to 8; and iv. An olefinically unsaturated crosslinking agent containing 2, 3, 4 or 5 olefinically unsaturated groups.

13. A water-in-water polymer dispersion, characterized in that, The water-in-water polymer dispersion is obtained by the method according to any one of claims 8 to 11.

14. Use of the polymer dispersion according to claim 12 or 13 in the following respects: • Used as a flocculant in solid sedimentation, flotation, or filtration. • Used as a thickener • Used as a pollutant control agent, • Used as a dry strength agent, • Or it can be used as a retention aid or filter aid in papermaking.

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