HIGH MOLECULAR WEIGHT POLYMER DISPERSIONS PRODUCED IN THE BATCH REACTOR

Abstract

The present invention relates to a batch reactor containing an aqueous reaction mixture for the production of a water-in-water polymer dispersion by radical polymerization, wherein the batch reactor comprises a stirrer treated by an abrasive polishing technique, or wherein the batch reactor is free of baffles. The present invention further relates to a process for producing a water-in-water polymer dispersion by radical polymerization in the batch reactor. In addition, the present invention relates to the use of the batch reactor in a process for producing a water-in-water polymer dispersion.

Description

[0001] The present invention relates to a batch reactor containing an aqueous reaction mixture for producing a water-in-water polymer dispersion by radical polymerization, wherein the batch reactor comprises a stirrer treated by an abrasive polishing technique or wherein the batch reactor is free of baffles. Furthermore, the present invention relates to a process for producing a water-in-water polymer dispersion by radical polymerization in the batch reactor. Furthermore, the present invention relates to the use of the batch reactor in a process for producing a water-in-water polymer dispersion.

[0002] The primary goal is to unlock the potential of water and renewable resources to create a safer, healthier, and more sustainable world. Countless industrial processes are water-based. The replacement of environmentally harmful substances or their volume reduction in water-based processes forms the basis for more sustainable solutions. The invention addresses this primary goal in the field of water-in-water (W / W) polymer dispersions. Improvements to W / W polymer dispersions directly correlate with sustainability in downstream applications, such as the papermaking process. The better such W / W polymer dispersions function as additives in water-based processes, such as the papermaking process, the fewer such process additives need to be used. Furthermore, the replacement of hydrocarbons supports the primary goal.

[0003] In addition to applications in other technical fields, the water-in-water polymer dispersions are suitable as flocculants, drainage aids, and retention aids in papermaking. Paper is produced by first preparing an aqueous slurry of cellulose fibers with a water content of more than 95 wt.%. The finished paper sheet has a water content of less than 5 wt.%. Drainage and retention are crucial steps in papermaking and are important for an efficient papermaking process. High-performance water-in-water polymer dispersions are a key factor in the papermaking process.

[0004] A well-known flocculant is a w / w polymer dispersion produced by copolymerizing ethylenically unsaturated monomers in an aqueous system containing a polymer dispersant, resulting in a dispersion containing the polymer dispersant and the synthesized copolymer. US8476391 B2 and US7323510B2 are early publications of such w / w polymer dispersions. It is well known in this technical field that the addition of separately synthesized copolymers, on the one hand, and polymer dispersants, on the other, leads to products with completely different properties than the w / w polymer dispersions disclosed in the above-mentioned patent documents. Copolymerization within a system containing the polymer dispersant is required to obtain high-performance flocculant products, e.g., for papermaking.

[0005] These circumstances make the production of water-in-water polymer dispersions a multi-parameter system. The type of ethylenically unsaturated monomer, its ratio, and the type of polymer dispersant are just a few of the parameters that influence the properties of the water-in-water polymer dispersion. Improving the properties of the final water-in-water polymer dispersion product has been the subject of numerous research and development efforts.

[0006] Those skilled in the art know how to radically polymerize monomers in a reaction mixture. Efforts are being made to find parameters that have a beneficial effect on complex polymer systems and offer the possibility of improving their properties. Beyond the properties of the final product, the w / w polymer dispersion, there is also a need to improve the process itself. In this context, there is a need to improve the process in terms of efficiency. The process is more efficient the less standby time there is. It has been observed that agglomeration and deposits occur during the w / w polymer dispersion production process, with these deposits requiring maintenance for cleaning.Furthermore, it was found that small amounts of agglomerated particles can be released from the stirrer or parts of the reactors located near flow-free or non-flow areas. Even such small amounts cause problems during the processing of the polymer dispersions or in downstream applications.

[0007] The object underlying the invention is to overcome the disadvantages of the prior art. In particular, the object underlying the invention relates to the provision of means in the process for producing a water-in-water polymer dispersion that result in an improved product and lead to improved handling and improved efficiency of the process for producing water-in-water polymer dispersions.

[0008] The objects underlying the invention are achieved by the subject matter of claim 1. Thus, according to a first aspect, the invention relates to a batch reactor containing an aqueous reaction mixture for producing a water-in-water polymer dispersion by radical polymerization, wherein the aqueous reaction mixture comprises a) a polymeric dispersant; b) a monomer composition comprising radically polymerizable monomers, wherein the radically polymerizable monomers are selected from the group consisting of one or more of a nonionic ethylenically unsaturated monomer, cationic ethylenically unsaturated monomer, and amphiphilic ethylenically unsaturated monomer; and c) an initiator, wherein the batch reactor comprises a stirrer treated by an abrasive polishing technique, or wherein the batch reactor is free of baffles.

[0009] Two alternative features lead to technical improvements and to the solution of the problems underlying the above invention. The first alternative relates to the batch reactor comprising a stirrer treated with an abrasive polishing technique. This means that before the stirrer is used in the batch reactor to apply the process for preparing the w / w polymer dispersion, the stirrer has been treated accordingly. This modifies the surface of the stirrer. In prior art documents, stirrers are sometimes coated with an enamel layer. However, the enamel can flake off from the metallic stirrer surface. This leads to the presence of artifacts in the product, which is associated with major disadvantages. If the stirrer is untreated, on the other hand, there is the disadvantage of deposits that require periodic maintenance of the batch reactor, making the process inefficient.

[0010] The second alternative feature relates to the absence of baffles in the batch reactor. Baffles cause mixing of reaction mixtures. However, there are spaces that are free of flow or where the flow has a very low velocity. Such spaces can be designated as flow-free areas or no-flow areas. Agglomerations can occur on surfaces closed to such areas. Such agglomerations degrade the final product, or if they deposit on the surface of the batch reactor, such deposits may require maintenance. Such maintenance, in turn, renders the process inefficient.

[0011] The two alternative features are features of the batch reactor. The advantages of these two features are related to the type of reaction that takes place in the batch reactor. The advantages are therefore advantages of the batch reactor, in which the reaction for producing water-in-water polymer dispersions takes place.

[0012] Both alternative features, i.e., the abrasive polishing-treated stirrer and the baffle-free batch reactor, can be implemented in a batch reactor. Thus, according to a preferred embodiment, the batch reactor comprises a stirrer treated with an abrasive polishing technique, and the batch reactor is baffle-free.

[0013] The process comprises providing a reaction mixture comprising the monomers to be copolymerized and a polymeric dispersant. The monomers are polymerized in the presence of the polymeric dispersant in an aqueous medium. According to well-known technical knowledge, a polymer dispersion obtained by the process according to the invention cannot be obtained by subjecting the monomer composition to copolymerization, followed by the addition of the polymeric dispersant after copolymerization. By applying the process in a batch reactor with the two alternative features mentioned, unique properties are imparted to the polymer dispersion, whereby the polymer dispersion represents the final product comprising the copolymer obtained from the radically polymerizable monomers together with the polymeric dispersant.

[0014] According to a preferred embodiment, the batch reactor comprises a stirrer treated with an abrasive polishing technique, wherein the abrasive polishing technique is an electropolishing technique. According to a non-binding theory, the electropolishing technique exhibits the advantageous effect due to the surface structure induced by the technique. The combination of the type of products produced with a stirrer treated in this way leads to the solution of the above-mentioned objects.

[0015] Electrochemical polishing is a technique known as anodic polishing or electrolytic polishing, an electrochemical process that removes material from a metallic workpiece, reduces surface roughness by smoothing micro-peaks and valleys, and improves surface quality. Electropolishing is often compared to electrochemical machining, but is quite different. It is used for polishing, passivating, and deburring metal parts.

[0016] According to a preferred embodiment, the batch reactor comprises the stirrer treated by the electropolishing technique, and the inner walls of the batch reactor are at least partially covered with enamel. The stationary parts of the batch reactor can be covered with enamel, as the risk of parts of the enamel chipping off is very low.

[0017] The batch reactor contains an aqueous reaction mixture comprising a polymeric dispersant, a monomer composition, and an initiator. These components are described in combination with the aspect of the present invention as described below.

[0018] The objects underlying the invention are further achieved by the subject matter of claim 4. Thus, according to a second aspect, the invention relates to a process for producing a water-in-water polymer dispersion, wherein the process is carried out in a batch reactor and the process comprises a step in which an aqueous reaction mixture is subjected to radical polymerization in order to synthesize a dispersed polymer and form the water-in-water polymer dispersion, this aqueous reaction mixture a) a polymeric dispersant; b) a monomer composition comprising radically polymerizable monomers, wherein the radically polymerizable monomers are selected from the group consisting of one or more of a nonionic ethylenically unsaturated monomer, cationic ethylenically unsaturated monomer, and amphiphilic ethylenically unsaturated monomer;and c) an initiator, wherein the batch reactor comprises a stirrer treated by an abrasive polishing technique, or wherein the batch reactor is free of baffles.;

[0019] As described above, the process for producing the W / W polymer dispersion and also the W / W polymer dispersion obtained from the process according to the invention are improved by the properties of the batch reactor. According to a preferred embodiment, the abrasive polishing technique is an electropolishing technique. According to another preferred embodiment, the batch reactor comprises the stirrer treated by the electropolishing technique, and the inner walls of the batch reactor are at least partially covered with enamel.

[0020] According to the invention, the aqueous reaction mixture comprises a monomer composition comprising radically polymerizable monomers.

[0021] In a preferred process, the monomer composition comprises the radically polymerizable monomers selected from the group consisting of one or more of the following: i. a non-ionic monomer of formula (I)wherein R 1 hydrogen or methyl; R 2 and R 3 are independently hydrogen, C1-C5 alkyl or C1-C5 hydroxyalkyl, ii. a cationic monomer of formula (II)wherein R 1 hydrogen or methyl; Z1 is O, NH, NR4, where R4 is C1-C4 alkyl, preferably methyl Y is one of wherein Y0 and Y1 are a C1-C6 alkylene group, optionally substituted with one or more hydroxyl groups, preferably ethylene or propylene, optionally substituted with a hydroxyl group; Y2, Y3, Y5, Y6, Y7 are each independently C1-C6 alkyl, preferably methyl; and Z -a counterion, preferably a halogen, pseudohalogen, acetate or SO4CH3 - ; iii. an amphiphilic monomer of formula (III) or (IV) wherein Z1 is O, NH, NR4, where R4 is C1-C4 alkyl, preferably methyl, R1 is 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 a C8-C 32 -alkyl, optionally substituted by one or more hydroxyl groups, preferably C 12 -C 20 -alkyl, optionally substituted with a hydroxyl group, and Z - a counterion, preferably a halogen, pseudohalogen, acetate or SO4CH3 - orwherein Z1 is O, NH, NR4, where R4 is C1-C4 alkyl, preferably methyl R 1 hydrogen or methyl, R 10 Hydrogen, C8-C 32 -Alkyl, C8-C 32 -aryl and / or C8-C32 -aralkyl, preferably C 12 -C 20 -Alkyl means R9 is a C1-C6 alkylene group, preferably an ethylene group or propylene group, and n is an integer between 1 and 50, preferably between 2 and 30, more preferably between 3 and 15, most preferably between 4 and 8; and iv. an ethylenically unsaturated crosslinker having 2, 3, 4 or 5 ethylenically unsaturated groups.

[0022] In the context of the present invention, a cationic monomer is a monomer that permanently carries a positive charge.

[0023] According to the preferred embodiment, one or more of the above monomers mentioned under points i. to iv. are used as monomers in the monomer composition to be polymerized. It is preferred that a copolymer is polymerized, i.e., that two of the monomers mentioned above under points i. to iv. are provided for the monomer composition to be polymerized. It is preferred that one monomer from point i. and one monomer from point ii. are provided for the monomer composition subjected to copolymerization. In a preferred embodiment, the radically polymerizable monomers comprise a radically polymerizable non-ionic monomer according to the general formula (I); and a radically polymerizable cationic monomer according to the general formula (II). These monomers are copolymerized and are advantageous for achieving the above objects.

[0024] More preferably, a monomer of item i., a monomer of item ii., and a monomer of item iv. are provided for the monomer composition subjected to copolymerization.

[0025] In a preferred embodiment, the process is characterized in that the monomer composition comprising the radically polymerizable monomers comprises at least the nonionic monomer of formula (I) selected from those wherein R 1 hydrogen or methyl, and R 2 and R 3 both are hydrogen, hydrogen and C1-C3 alkyl, hydrogen and hydroxyethyl or both are C1-C3 alkyl, and / or the cationic monomer of formula (II) selected from those wherein R 1 is hydrogen or methyl and Z1 is O, NH or NR4, wherein R4 is methyl, Y1 is C2-C6 alkylene, preferably ethylene or propylene, Y5, Y6 and Y7 are all methyl, and Z - is a halogen.

[0026] In a preferred embodiment, the radically polymerizable monomers comprise a radically polymerizable non-ionic monomer according to the general formula (I) which is selected from the group consisting of (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.

[0027] In a further preferred embodiment, the radically polymerizable monomers comprise a radically polymerizable cationic monomer according to general formula (II) selected from the group consisting of trimethylammonium C2-C6 alkyl (meth)acrylate halides and trimethylammonium C2-C6 alkyl (meth)acrylamide halides. In a particularly highly preferred embodiment, the monomer composition comprises a radically polymerizable monomer which is (meth)acrylamide, together with a radically polymerizable monomer selected from trimethylammonium C2-C6 alkyl (meth)acrylate halides, in particular an acryloyloxyethyl trimethylammonium halide.

[0028] According to a preferred embodiment, the monomer composition comprising free-radically polymerizable monomers contains a crosslinker. Crosslinkers are known to those skilled in the art. In this preferred embodiment, the monomer composition preferably contains 0.0001 to 1.25 wt. % of one or more preferably ethylenically unsaturated crosslinkers, based on the total weight of the monomers. If ethylenically unsaturated crosslinkers are present, they contain 2, 3, 4, or 5 ethylenically unsaturated groups that are free-radically polymerizable.

[0029] Examples of crosslinkers with two radically polymerizable, ethylenically unsaturated groups are: (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) Alkylenedi(meth)acrylamides, e.g. N-methylenedi(meth)acrylamide, N,N'-3-methylbutylidenebis(meth)acrylamide, N,N'-(1,2-dihydroxyethylene)bis(meth)acrylamide, and preferably N,N'-hexamethylenebis(meth)acrylamide, and particularly preferably N,N'-methylenebis(meth)acrylamide; (3) Polyalkoxydi(meth)acrylates according to the following general formula, R 10 is hydrogen or methyl; R 11 is selected from -CH2CH2-, -CH2CH2CH2-, -CH2CH2CH2CH2-, -CH2CH2CH2CH2CH2- or -CH2CH2CH2CH2CH2CH2-; and m is an integer in the range 2-50.

[0030] Examples of crosslinkers according to the above general formula include polypropylene glycol di(meth)acrylates with m in the range of 4-25; polybutylene glycol di(meth)acrylates with m in the range of 5-40; and preferably polyethylene glycol di(meth)acrylates with m in the range of 2-45, e.g. diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate; and, more preferably, polyethylene glycol di(meth)acrylates with m in the range of 5-20; (4) Examples of other di(meth)acrylates that can be used are benzylidene di(meth)acrylate, bisphenol A di(meth)acrylate, 1,3-di(meth)acryloyloxy-Z-propanol, hydroquinone di(meth)acrylate, ethanedithiol di(meth)acrylate, propanedithiol di(meth)acrylate, polyethylenedithiol di(meth)acrylate and polypropylenedithiol di(meth)acrylate; (5) Divinyl compounds, e.g. 1,4-butanediol divinyl ether, divinylbenzene, butadiene, 1,6-hexadiene; di(meth)allyl compounds, such as di(meth)allyl phthalate or di(meth)allylsuccinate; vinyl(meth)acrylic compounds, e.g. vinyl(meth)acrylate; or preferably (meth)allyl(meth)acrylic compounds, e.g. allyl(meth)acrylate.

[0031] Examples of crosslinkers with 3 or more ethylenically unsaturated, radically polymerizable groups are glycerol tri(meth)acrylate, 2,2-dihydroxymethyl-1-butanol tri(meth)acrylate, trimethylolpropane triethoxytri(meth)acrylate, trimethacrylamide, (meth)allylidene di(meth)acrylate, 3-allyloxy-1,2-propanediol di(meth)acrylate, triallylamine, triallyl cyanurate or triallyl isocyanurate; and (as representative compounds with more than 3 ethylenically unsaturated, radically polymerizable groups) pentaerythritol tetra(meth)acrylate and N,N,N'N'-tetra(meth)acryloyl-1,5-pentanediamine.

[0032] An example of a crosslinker with 5 ethylenically unsaturated, radically polymerizable groups is dipentaerithritol pentaacrylate.

[0033] Particularly preferred crosslinkers are selected from the group consisting of methylenebisacrylamide, polyethylene glycol diacrylate and triallylamine.

[0034] Other preferred crosslinkers are asymmetrically crosslinkable monomers, i.e., crosslinkable monomers that rely on different functional groups for incorporation into the polymer backbone and the crosslinking reaction. Examples of such asymmetrically crosslinkable monomers are N'-methylolacrylamide, N'-methylolmethacrylamide, and glycidyl (meth)acrylate.

[0035] Crosslinkers of this type have the advantage that crosslinking can be initiated sequentially. Thus, crosslinking can occur under different conditions than the radical polymerization of the main backbone. Preferably, crosslinking is initiated after changing the reaction conditions, e.g., 6-9% of the pH (addition of acid or base), the temperature, and the like. Optionally, the monomer composition further comprises a hydrophobic monomer, preferably a hydrophobic C4-18 alkyl (meth)acrylate, and / or an ethylenically unsaturated monomer.

[0036] In a preferred embodiment, the process is characterized in that the radically polymerizable monomers are selected from the non-ionic monomer of formula (I) and / or the cationic monomer of formula (II), wherein the amount of radically polymerizable monomers selected from the non-ionic monomer of formula (I) and / or the cationic monomer of formula (II) is between 80 and less than 100 wt.%, preferably 85 and 99 wt.%, most preferably 90 and 95 wt.%, based on the total amount of radically polymerizable monomers, the remainder being selected from the group consisting of any other ethylenically polymerizable monomer, a monomer of formula (III), a monomer of formula (IV) and the ethylenically unsaturated crosslinker having 2, 3, 4 or 5 ethylenically unsaturated groups.

[0037] The sum of the values ​​in wt. % need not be 100 wt. %, since, in addition to the monomers of formulas (I) and / or (II), other ethylenically unsaturated monomers may be present in the monomer composition, i.e., the reaction mixture, which must be taken into account when determining the total amount of monomers. In a preferred embodiment, however, the monomer composition consists of monomers (a) and (b), so that the sum of the two values ​​in wt. % is 100 wt. %, i.e., no further monomers are present.

[0038] In a preferred embodiment, the monomer composition comprises - at least 5% by weight, preferably at least 20% by weight of the non-ionic monomer of formula (I) R 1 hydrogen or methyl; R 2 and R 3 are independently hydrogen, C1-C5 alkyl or C1-C5 hydroxyalkyl; - at least 5% by weight, preferably at least 20% by weight, particularly preferably 25 to 47% by weight, most preferably 50.5 to 80% by weight, of the cationic monomer of formula (II) R 1 hydrogen or methyl; Z1 is O, NH, NR4, where R4 is C1-C4 alkyl, preferably methyl Y is one of Y0 and Y1 are a C1-C6 alkylene group optionally substituted with one or more hydroxyl groups, preferably ethylene or propylene optionally substituted with a hydroxyl group; Y2, Y3, Y5, Y6, Y7 are each independently C1-C6 alkyl, preferably methyl; and Z - a counterion, preferably a halogen, pseudohalogen, acetate or SO4CH3 - ; - 0.0001 to 1.25% by weight, preferably 0.0005 to 1% by weight of the ethylenically unsaturated crosslinker having 2, 3, 4 or 5 ethylenically unsaturated groups; and - optionally further ethylenically unsaturated monomers.

[0039] Here, too, the sum of the values ​​in wt. % need not be 100 wt. %, since, in addition to the monomers of formulas (I) and / or (II), further ethylenically unsaturated monomers may be present in the monomer composition, i.e., in the reaction mixture, which must be taken into account when determining the total amount of monomers. In a preferred embodiment, however, the monomer composition consists of monomers (a) and (b), so that the sum of the two values ​​in wt. % is 100 wt. %, i.e., no further monomers are present.

[0040] In the present application, all percentages relating to the monomer composition refer to the total amount of monomers.

[0041] According to the invention, the aqueous reaction mixture comprises a polymeric dispersant.

[0042] According to the prior art, alternative aqueous polymer systems are stabilized by low-molecular-weight salts. A high salt content ensures the stability of the polymer system. In contrast to these systems, the stabilization of the inventive W / W polymer dispersion is fundamentally ensured by the polymeric dispersant. This system eliminates the need for a high salt concentration, as is common in prior-art aqueous polymer systems. In a preferred embodiment, the polymer dispersion has a salt content of less than 15 wt. %, particularly preferably a salt content of 0.1 to 10 wt. %, most preferably 1 to 5 wt. %, based on the polymer dispersion. The term "salt content" refers to salts with low molecular weight. The polymeric electrolytes are not taken into account when calculating the salt content.

[0043] In a preferred embodiment, the cationic polymeric dispersant is substantially linear, ie, it is not derived from monomer mixtures with crosslinkers.

[0044] In a preferred embodiment, the polymeric dispersant is derived from one or more radically polymerizable, ethylenically unsaturated monomers. Preferably, the polymeric dispersant is derived from one type of radically polymerizable, ethylenically unsaturated monomer, i.e., the polymeric dispersant is essentially a homopolymer. The term "essentially" in this context means that no second type of monomer is intentionally added during the synthesis of the polymeric dispersant.

[0045] Preferably, the polymeric dispersant is derived from one or more cationic monomers, more preferably from a single cationic monomer.

[0046] In a further preferred embodiment, the process is characterized in that the polymeric dispersant is a homopolymer prepared from the cationic monomer of formula (II) R 1 hydrogen or methyl; Z1 is O, NH, NR4, where R4 is C1-C4-alkyl, preferably methyl Y is one of Y0 and Y1 are a C1-C6 alkylene group optionally substituted with one or more hydroxyl groups, preferably ethylene or propylene optionally substituted with a hydroxyl group; Y2, Y3, Y5, Y6, Y7 are each independently C1-C6 alkyl, preferably methyl; and Z - a counterion, preferably a halogen, pseudohalogen, acetate or SO4CH3.

[0047] Preferably, Y1, Y2 and Y3 are identical, preferably methyl. In a preferred embodiment, Z1 is O or NH, Y0 is ethylene or propylene, R 1Hydrogen or methyl, and Y1, Y2, and Y3 are methyl. The cationic monomer according to general formula (II) can be an ester (Z1 = O), such as trimethylammonium ethyl (meth)acrylate (ADAME quat.). However, the cationic monomer according to general formula (I) is preferably an amide (Z1 = NH), in particular trimethylammonium propylacrylamide (DIMAPA quat).

[0048] Bevorzugte radikalisch polymerisierbare kationische Monomere nach allgemeiner Formel (II) umfassen quaternierte Dialkylaminoalkyl(meth)acrylate oder Dialkylaminoalkyl(meth)acrylamide mit 1 bis 3 C-Atomen in den Alkyl- oder Alkylengruppen, besonders bevorzugt das Methylchloridquaternierte Ammoniumsalz von Dimethylaminomethyl(meth)acrylat, Dimethylaminoethyl(meth)acrylat, Dimethylaminopropyl(meth)acrylat, Diethylaminomethyl(meth)acrylat, Diethylaminoethyl-(meth)acrylat, Diethylaminopropyl(meth)acrylat, Dimethylaminomethyl(meth)acrylamid, Dimethylaminoethyl(meth)acrylamid, Dimethylaminopropyl(meth)acrylamid, Diethylaminomethyl(meth)acrylamid, Diethylaminoethyl(meth)acrylamid, Diethylaminopropyl(meth)-acrylamid.

[0049] Quaternized dimethylaminoethyl acrylate and dimethylaminopropylacrylamide are particularly preferred. Quaternization can be influenced by the use of dimethyl sulfate, diethyl sulfate, methyl chloride, or ethyl chloride. In a preferred embodiment, monomers are quaternized with methyl chloride.

[0050] In a preferred embodiment, the polymeric dispersant is a homopolymer of trimethylammonium propylacrylamide chloride (DIMAPA quat), which is referred to by IUPAC as (3-acrylamidopropyl)trimethylammonium chloride (APTAC).

[0051] Preferably, the polymeric dispersant is derived from a monomer composition comprising a cationic monomer selected from the group consisting of (alk)acrylamidoalkyltrialkylammonium halides (e.g., trimethylammonium alkyl(meth)acrylamide halides), (alk)acryloyloxyalkyltrialkylammonium halides (e.g., trimethylammonium alkyl(meth)acrylate halides), alkenyltrialkylammonium halides, and dialkenyldialkylammonium halides (e.g., diallyldialkylammonium halides). More preferably, the polymeric dispersant is a cationic polymer derived from a monomer composition comprising a cationic monomer selected from the group consisting of trimethylammonium alkyl(meth)acrylate halides, trimethylammonium alkyl(meth)acrylamide halides, and diallyldialkylammonium halides.Preferably, the aforementioned cationic monomers comprise 6 to 25 carbon atoms, more preferably 7 to 20 carbon atoms, most preferably 7 to 15 carbon atoms and especially 8 to 12 carbon atoms.

[0052] In a further preferred embodiment, the polymeric dispersant is derived from a dialkenyldialkylammonium halide, preferably a diallyldimethylammonium halide (DADMAC).

[0053] According to a preferred embodiment, the process is characterized in that the polymeric dispersant is a homopolymer prepared from a (meth)acryloylamidopropyltrimethylammonium salt or a (meth)acryloyloxyethyltrimethylammonium salt. For the purposes of this disclosure, a homopolymer of a (meth)acrylate means that the homopolymer is either a methacrylate or an acrylate.

[0054] For the purposes of this application, the halide may be any acceptable halide, such as chloride, bromide, or iodide; the counterions of the salts may be any acceptable counterions, such as halides, methosulfates, sulfates, or others.

[0055] According to a preferred embodiment, the process is characterized in that the polymeric dispersant has a weight-average molecular weight M determined by size exclusion chromatography. w from 40,000 to less than 150,000 g / mol, preferably 50,000 to 140,000 g / mol, particularly preferably 60,000 to 130,000, most preferably 85,000 to 120,000 g / mol.

[0056] In a preferred embodiment, the process is characterized in that the viscosity of the polymer dispersion is 1,800 mPas to less than 6,700 mPas, preferably 2,000 mPas to 6,000 mPas, particularly preferably 2,200 mPas to 5,500 mPas, most preferably 2,500 mPas to 5,000 mPas, measured with a Brookfield viscometer with spindle 4 at 20°C and an angular speed of 10 rpm.

[0057] The viscosity is preferably the volume viscosity, which refers to the viscosity immediately after receiving the cooled product.

[0058] According to a preferred embodiment, the ratio of the polymeric dispersant to the dispersed 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, particularly 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, in particular in the range of 0.65:1 to 0.9:1.

[0059] The invention is particularly efficient when the process is characterized in that the total weight of the polymeric dispersant, based on the total weight of the polymer dispersion, is in the range from 10 to 28 wt.%, preferably 12 to 26 wt.%, particularly preferably 14 to 24 wt.%, even more preferably 16 to 22 wt.%. According to a further embodiment, the process is characterized in that the total weight of the polymeric dispersant, based on the total weight of the polymer dispersion, is between 18 and 26 wt.%, preferably 19 to 25 wt.%.

[0060] The aqueous reaction mixture also contains an initiator. In a preferred embodiment, the initiator is a redox initiator system comprising an oxidizing agent and a reducing agent.

[0061] According to preferred embodiments, the process is characterized in that the step of subjecting an aqueous reaction mixture to a radical polymerization is carried out by sequentially or simultaneously adding a redox initiator system. With the sequential addition of the initiator to the batch reactor, the first time phase begins by definition with the injection of the first portion of the initiator. The second time phase only begins when all of the initiator used to initiate the polymerization has been injected into the batch reactor; however, the portions of the initiator injected to destroy residual monomers do not count toward the beginning of the second time phase.

[0062] According to a preferred embodiment, the process is characterized in that the oxidizing agent has a redox potential of 0.6 to 2.0 V. Preferred oxidizing agents used in the redox initiator system to control the adiabatic conditions are peroxydiphosphates, hydrogen peroxide (1.14 V), alkyl hydroperoxides, more preferably t-butyl hydroperoxide, or aryl hydroperoxides, particularly preferably cumene hydroperoxide. According to a particularly highly preferred embodiment, the process is characterized in that the oxidizing agent is selected from alkyl hydroperoxides, in particular t-butyl hydroperoxide, or aryl hydroperoxides, in particular cumene hydroperoxide.

[0063] Persulfates can also be used as agents in an initiator system. However, it has been shown that persulfates with a redox potential of 2.01 V do not influence the manufacturing process sufficiently to meet the requirement that the process be carried out under controlled adiabatic conditions. If persulfates are used as initiators in the present process, another oxidizing agent with a potential of 2 V or less and 0.6 V or more is used in the redox initiator system. In a preferred embodiment, however, the redox initiator system is free of a persulfate salt.

[0064] In a preferred embodiment, the process is characterized in that the reducing agent has a redox potential of -2 to 0.3 V. Preferred reducing agents are selected from sodium bisulfite, potassium bisulfite, ammonium bisulfite, sodium sulfite (-1.12 V), potassium sulfite, ammonium sulfite, a hydrogen sulfite (-0.08 V); a thiosulfate (-0.017 V); an amine; an acid, particularly preferably ascorbic acid (0.127 V) or erythorbic acid (0.127 V). Particularly preferred reducing agents are bisulfites, in particular sodium bisulfite, potassium bisulfite, or ammonium bisulfite.

[0065] The redox potential is determined using standard methods known to those skilled in the art.

[0066] In a very preferred embodiment, the redox initiator system comprises an alkyl / aryl hydroperoxide together with a bisulfite.

[0067] In a preferred embodiment, more oxidizing agent is used than reducing agent by mass. According to a preferred embodiment, the process is characterized in that the weight ratio between the reducing agent and the oxidizing agent is below 35:1 and above 2:1, preferably below 15:1 and above 3:1, particularly preferably below 9:1 and above 4:1.

[0068] In a further preferred embodiment, the process is characterized in that the polymerization step is carried out by stirring while measuring the torque of a motor-driven stirrer. Alternatively, the process is characterized in that step B of the polymerization is carried out by stirring and the torque of a motor-driven stirrer is kept below 65 N / cm.

[0069] According to a preferred embodiment, the process comprises the step of reducing the residual monomer content by adding an initiator to the reaction mixture at approximately the time of reaching the maximum temperature (T max ). In a particularly preferred embodiment, the step is carried out isothermally, even more preferably the step is carried out such that the temperature during this step is maintained at a level above 55°C and below 80°C, most preferably above 60°C and below 70°C.

[0070] The initiator used to reduce the residual monomer content can be one of the additional initiators mentioned above. However, it is preferred that the initiator be selected from a peroxide or an azo compound, more preferably selected from the group consisting of a hydroperoxide, a dialkyl peroxide, a diacyl peroxide, and an azo compound substituted by tertiary carbon atoms, preferably bearing alkyl groups, nitrile groups, and / or ester groups. In particular, the initiator used in step C is 2,2'-azobis(2-amidinopropane) dihydrochloride (V-50).

[0071] The objects underlying the invention are further achieved by the subject matter of claim 12. Thus, according to a third aspect, the invention relates to the use of a batch reactor in a process for producing a water-in-water polymer dispersion, the process comprising a step in which an aqueous reaction mixture is subjected to radical polymerization to synthesize a dispersed polymer and form the water-in-water polymer dispersion, said aqueous reaction mixture comprising a) a polymeric dispersant; b) a monomer composition comprising radically polymerizable monomers, wherein the radically polymerizable monomers are selected from the group consisting of one or more of a nonionic ethylenically unsaturated monomer, cationic ethylenically unsaturated monomer, and amphiphilic ethylenically unsaturated monomer;and c) an initiator, wherein the batch reactor comprises a stirrer treated by an abrasive polishing technique, or wherein the batch reactor is free of baffles.;

[0072] A further aspect of the invention as disclosed here relates to the use of the polymer dispersion according to the invention a. as a flocculant in the sedimentation, flotation or filtration of solids, b. as a thickener, c. as a pollution control agent, d. as a dry strength aid, retention agent or drainage aid in papermaking.

[0073] Preferred embodiments of this aspect are characterized in that features are disclosed in combination with any of the first to third aspects of the invention.

[0074] Yet another aspect of the invention as disclosed here relates to a W / W polymer dispersion obtained by a process according to the second aspect of the invention.

[0075] Preferred embodiments of this aspect are characterized in that features are disclosed in combination with any of the first to third aspects of the invention.

[0076] Features relating to preferred embodiments of the first aspect of the present invention, which are disclosed exclusively with respect to the first aspect of the invention, also represent preferred embodiments of the second and third embodiments.

[0077] In the following, exemplary embodiments (A) to (H) are disclosed, which represent particularly preferred embodiments. (A) Batch reactor containing an aqueous reaction mixture for producing a water-in-water polymer dispersion by radical polymerization, wherein the aqueous reaction mixture comprises a) a polymeric dispersant; b) a monomer composition comprising radically polymerizable monomers, wherein the radically polymerizable monomers are selected from the group consisting of one or more nonionic ethylenically unsaturated monomers, a cationic ethylenically unsaturated monomer, and an amphiphilic ethylenically unsaturated monomer; and c) an initiator,wherein the batch reactor comprises a stirrer which is operated by an electropolishing technique was treated, or wherein the batch reactor comprises a stirrer treated by an electropolishing technique and the batch reactor is free of baffles. (B) Batch reactor containing an aqueous reaction mixture for producing a water-in-water polymer dispersion by radical polymerization, wherein the aqueous reaction mixture comprises a) a polymeric dispersant; b) a monomer composition comprising radically polymerizable monomers, wherein the radically polymerizable monomers are selected from the group consisting of one or more nonionic ethylenically unsaturated monomers, a cationic ethylenically unsaturated monomer, and an amphiphilic ethylenically unsaturated monomer; and c) an initiator, wherein the batch reactor comprises a stirrer which is operated by an electropolishing polishing technique was treated, or wherein the batch reactor is free of baffles; wherein the polymeric dispersant is a homopolymer prepared from the cationic monomer of formula (II) R1 hydrogen or methyl; Z1 is O, NH, NR4, where R4 is C1-C4-alkyl, preferably methyl Y is one of Y0 and Y1 are a C1-C6 alkylene group optionally substituted with one or more hydroxyl groups, preferably ethylene or propylene optionally substituted with a hydroxyl group; Y2, Y3, Y5, Y6, Y7 are each independently C1-C6 alkyl, preferably methyl; and Z - a counterion, preferably a halogen, pseudohalogen, acetate or SO4CH3 - . (C) Batch reactor containing an aqueous reaction mixture for producing a water-in-water polymer dispersion by radical polymerization, wherein the aqueous reaction mixture comprises a) a polymeric dispersant; b) a monomer composition comprising radically polymerizable monomers, wherein the radically polymerizable monomers are selected from the group consisting of one or more nonionic ethylenically unsaturated monomers, a cationic ethylenically unsaturated monomer, and an amphiphilic ethylenically unsaturated monomer; and c) an initiator, wherein the batch reactor comprises a stirrer which is operated by an electropolishing polishing technique was treated, or wherein the batch reactor is free of baffles; wherein the polymeric dispersant is a homopolymer consisting of a (Meth)acryloylamidopropyltrimethylammonium salt or a (Meth)acryloyloxyethyltrimethylammonium salt. (D) Batch reactor containing an aqueous reaction mixture for producing a water-in-water polymer dispersion by radical polymerization, wherein the aqueous reaction mixture comprises a) a polymeric dispersant; b) a monomer composition comprising radically polymerizable monomers, wherein the radically polymerizable monomers are selected from the group consisting of one or more nonionic ethylenically unsaturated monomers, a cationic ethylenically unsaturated monomer, and an amphiphilic ethylenically unsaturated monomer; and c) an initiator, wherein the batch reactor comprises a stirrer treated by an electropolishing polishing technique, or wherein the batch reactor is free of baffles; wherein the polymeric dispersant is a homopolymer prepared from a (meth)acryloylamidopropyltrimethylammonium salt or a (meth)acryloyloxyethyltrimethylammonium salt; and wherein the monomer composition comprising the radically polymerizable monomers comprises at least the following two monomers: - at least 5% by weight, preferably at least 20% by weight of the non-ionic monomer of formula (I) R 1 hydrogen or methyl; R 2 and R 3 are independently hydrogen, C1-C5 alkyl or C1-C5 hydroxyalkyl; - at least 5% by weight, preferably at least 20% by weight, particularly preferably 25 to 47% by weight, most preferably 50.5 to 80% by weight, of the cationic monomer of formula (II) R 1 hydrogen or methyl; Z1 is O, NH, NR4, where R4 is C1-C4-alkyl, preferably methyl Y is one of Y0 and Y1 are a C1-C6 alkylene group optionally substituted with one or more hydroxyl groups, preferably ethylene or propylene optionally substituted with a hydroxyl group; Y2, Y3, Y5, Y6, Y7 are each independently C1-C6 alkyl, preferably methyl; and Z - a counterion, preferably a halogen, pseudohalogen, acetate or SO4CH3. (E) A process for preparing a water-in-water polymer dispersion, wherein the process is carried out in a batch reactor and the process comprises a step of subjecting an aqueous reaction mixture to radical polymerization to synthesize a dispersed polymer and form the water-in-water polymer dispersion, said aqueous reaction mixture comprising a) a polymeric dispersant; b) a monomer composition comprising radically polymerizable monomers, wherein the radically polymerizable monomers are selected from the group consisting of one or more nonionic ethylenically unsaturated monomers, a cationic ethylenically unsaturated monomer, and an amphiphilic ethylenically unsaturated monomer; and c) an initiator, wherein the batch reactor comprises a stirrer which is operated by an electropolishing polishing technique was treated, or wherein the batch reactor comprises a stirrer treated by an electropolishing technique and the batch reactor is free of baffles. (F) A process for preparing a water-in-water polymer dispersion, the process being carried out in a batch reactor and comprising a step of subjecting an aqueous reaction mixture to radical polymerization to synthesize a dispersed polymer and form the water-in-water polymer dispersion, said aqueous reaction mixture comprising a) a polymeric dispersant; b) a monomer composition comprising radically polymerizable monomers, wherein the radically polymerizable monomers are selected from the group consisting of one or more nonionic ethylenically unsaturated monomers, a cationic ethylenically unsaturated monomer, and an amphiphilic ethylenically unsaturated monomer; and c) an initiator, wherein the batch reactor comprises a stirrer treated by an electropolishing polishing technique, or wherein the batch reactor is free of baffles; wherein the polymeric dispersant is a homopolymer prepared from the cationic monomer of formula (II) R 1 hydrogen or methyl; Z1 is O, NH, NR4, where R4 is C1-C4-alkyl, preferably methyl Y is one of Y0 and Y1 are a C1-C6 alkylene group optionally substituted with one or more hydroxyl groups, preferably ethylene or propylene optionally substituted with a hydroxyl group; Y2, Y3, Y5, Y6, Y7 are each independently C1-C6 alkyl, preferably methyl; and Z - a counterion, preferably a halogen, pseudohalogen, acetate or SO4CH3. (G) A process for preparing a water-in-water polymer dispersion, wherein the process is carried out in a batch reactor and the process comprises a step of subjecting an aqueous reaction mixture to radical polymerization to synthesize a dispersed polymer and form the water-in-water polymer dispersion, said aqueous reaction mixture comprising a) a polymeric dispersant; b) a monomer composition comprising radically polymerizable monomers, wherein the radically polymerizable monomers are selected from the group consisting of one or more nonionic ethylenically unsaturated monomers, a cationic ethylenically unsaturated monomer, and an amphiphilic ethylenically unsaturated monomer; and c) an initiator, wherein the batch reactor comprises a stirrer treated by an electropolishing polishing technique, or wherein the batch reactor is free of baffles; wherein the polymeric dispersant is a homopolymer made from a (meth)acryloylamidopropyltrimethylammonium salt or a (meth)acryloyloxyethyltrimethylammonium salt. (H) A process for preparing a water-in-water polymer dispersion, the process being carried out in a batch reactor and comprising a step of subjecting an aqueous reaction mixture to radical polymerization to synthesize a dispersed polymer and form the water-in-water polymer dispersion, said aqueous reaction mixture comprising a) a polymeric dispersant; b) a monomer composition comprising radically polymerizable monomers, wherein the radically polymerizable monomers are selected from the group consisting of one or more nonionic ethylenically unsaturated monomers, a cationic ethylenically unsaturated monomer, and an amphiphilic ethylenically unsaturated monomer; and c) an initiator, wherein the batch reactor comprises a stirrer treated by an electropolishing polishing technique, or wherein the batch reactor is free of baffles; wherein the polymeric dispersant is a homopolymer made from a (meth)acryloylamidopropyltrimethylammonium salt or a (meth)acryloyloxyethyltrimethylammonium salt. wherein the monomer composition comprising the radically polymerizable monomers comprises at least the following two monomers: - at least 5% by weight, preferably at least 20% by weight of the non-ionic monomer of formula (I) R 1 hydrogen or methyl; R 2 and R 3 are independently hydrogen, C1-C5 alkyl or C1-C5 hydroxyalkyl; - at least 5% by weight, preferably at least 20% by weight, particularly preferably 25 to 47% by weight, most preferably 50.5 to 80% by weight, of the cationic monomer of formula (II) R 1 hydrogen or methyl; Z1 is O, NH, NR4, where R4 is C1-C4-alkyl, preferably methyl Y is one of Y0 and Y1 are a C1-C6 alkylene group optionally substituted with one or more hydroxyl groups, preferably ethylene or propylene optionally substituted with a hydroxyl group; Y2, Y3, Y5, Y6, Y7 are each independently C1-C6 alkyl, preferably methyl; and Z -a counterion, preferably a halogen, pseudohalogen, acetate or SO4CH3. EXAMPLES

[0078] The test methods used are described in detail below: The volume viscosity is measured as follows: Use the product directly for measurement. Spindle No. 4 is slowly immersed in the product and the viscosity is determined using a Brookfield RVT viscometer at 10 rpm. The measurement is terminated when the reading remains constant for a period of 30 seconds.

[0079] The viscosity of the solution is measured in deionized water and determined as follows: A 5 wt% solution in water is prepared. 323.0 ± 0.1 g of demineralized water is weighed into a 400 ml beaker. Then, 17.0 ± 0.1 g of the product (22 ± 3 °C) are added while stirring at 300 rpm. The dissolution time is 60 min at 300 ± 10 rpm. The solution must then rest for 5 minutes. Spindle No. 2 is then slowly immersed, and the viscosity is determined using a Brookfield RFT viscometer at 10 rpm. The measurement is stopped when the reading remains constant for a period of 30 seconds.

[0080] The salt viscosity is measured in a 10% NaCl solution and determined as follows: Weigh 289.0 ± 0.1 g of demineralized water into a 400 ml beaker. Then, 17.0 ± 0.1 g of the product (22 ± 3 °C) are added while stirring at 300 rpm. The dissolution time is 45 minutes at 300 ± 10 rpm, after which 34.0 ± 0.1 g of NaCl are added. The solution is stirred for another 15 minutes. The solution must then stand for 5 minutes. Spindle No. 1 is then slowly immersed, and the viscosity is determined using a Brookfield RVT viscometer at 10 rpm. The measurement is stopped when the measured value remains constant for a period of 30 seconds.

[0081] The molecular weight is measured using size exclusion chromatography (SEC).

[0082] The measurement is carried out in particular to determine the molecular weight of the dispersant. Molecular weights are characterized by aqueous SEC using pullulan standards for calibration. Sample preparation:

[0083] The samples are diluted with the eluent (polymer make-down in a volumetric flask) and filtered through a 1µm filter (M&N) (via syringe) before injection. If the instrument is equipped with an autosampler, filter the solution through a 1µm filter into a vial.

[0084] Parameters used: Device: SEC (Agilent) Column: Novema 3000 (PSS) Detector: RI Eluent: 1.5 wt% formic acid in water Flow rate: 1 ml / min Calibration standards: Pullulan with different Mw

[0085] The following examples further illustrate the process for preparing the W / W polymer dispersion. However, the following examples should not be construed as limiting the invention. Example 1: Synthesis of the polymeric dispersant:

[0086] First, 294.06 g of water, 666.7 g of acryloylamidopropyltrimethylammonium chloride (DIMAPA quat.) (60 wt%), and sulfuric acid (50 wt%) were weighed into a 2-liter vessel to adjust the pH to 5.0 ± 0.2. The monomer solution was then purged with nitrogen for 30 min by stirring. The aqueous solution was then heated to 65°C, and 2-mercaptoethanol and V-50 (2,2'-azobis(2-amidinopropane) dihydrochloride) were added to the solution. After reaching Tmax, the vessel was cooled to ≤ 80°C. Two additional portions of the initiator (V-50) were then added to the product within 10 minutes to burn off the remaining monomer. The product was stirred at 70°C for 1 h. The final aqueous product was cooled to 30°C. The dispersants were provided in 40 wt% aqueous solutions.

[0087] Specifications: - Product viscosity [mPas]: 110-180 - pH value (pure): 4.9-5.3 - Total solids [%]: 40-43 - Mw SEC [g / mol]: 70000-110000 Example 2: Synthesis of polymer dispersion (charge density 15 mol%)

[0088] In a batch reactor without baffles and equipped with an electropolished stirrer, acrylamide and acryloyloxyethyltrimethylammonium chloride (ADAME quat.) were polymerized in an aqueous solution in the presence of homopolyacryloylamidopropyltrimethylammonium chloride (polymeric dispersant) in a discontinuous process (batch size 1,000 kg). The aqueous phase was prepared at 200 rpm.

[0089] First, 206.90 kg of soft water, 261.80 kg of bio-acrylamide (49 wt%), 77.20 kg of acryloyloxyethyltrimethylammonium chloride (ADAME quat) (80 wt%), 412.50 kg of polymeric dispersant from Example 1, 10.00 kg of ammonium sulfate, and 0.20 kg of Trilon C were charged into the reaction vessel. The pH was adjusted to 5.0±0.2 with approximately 0.10 kg of sulfuric acid (50%). The vessel was evacuated five times before being vented with nitrogen. The initiator composition was added at a vacuum of 0.5 bar and maximum stirrer speed. Initiation began at 22±1 °C with the addition of 0.34 kg of V-50 in 3.05 kg of soft water, 0.025 kg of sodium persulfate in 0.47 kg of soft water, 0.014 kg of sodium bisulfite in 0.27 kg of soft water, and 0.003 kg of t-butyl hydroperoxide (70%) in 1 kg of soft water. The vessel was then re-aerated with nitrogen.After reaching the maximum temperature, a solution of 0.17 kg of V-50 in 1.53 kg of soft water was added to reduce the monomer content. After a one-hour post-reaction period, the product was cooled to a temperature below 40°C. Subsequently, 8.30 kg of citric acid and 0.82 kg of the biocide Acticide SPX were added, and the product was cooled to a temperature below 30°C. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 8476391 B2

[0004] US 7323510B2

[0004]

Claims

[1] Batch reactor containing an aqueous reaction mixture for producing a water-in-water polymer dispersion by radical polymerization, wherein the aqueous reaction mixture comprises a) a polymeric dispersant; b) a monomer composition comprising radically polymerizable monomers, wherein the radically polymerizable monomers are selected from the group consisting of one or more nonionic ethylenically unsaturated monomers, a cationic ethylenically unsaturated monomer, and an amphiphilic ethylenically unsaturated monomer; and c) an initiator, wherein the batch reactor comprises a stirrer treated by an abrasive polishing technique, or The batch reactor is free of baffles. [2] Batch reactor according to claim 1, wherein the abrasive polishing technique is an electropolishing technique. [3] Batch reactor according to claim 1, wherein the batch reactor comprises the stirrer treated with the electropolishing technique and the inner walls of the batch reactor are at least partially coated with enamel. [4] A process for preparing a water-in-water polymer dispersion, the process being carried out in a batch reactor and the process comprising a step of subjecting an aqueous reaction mixture to radical polymerization to synthesize a dispersed polymer and form the water-in-water polymer dispersion, said aqueous reaction mixture comprising a) a polymeric dispersant; b) a monomer composition comprising radically polymerizable monomers, wherein the radically polymerizable monomers are selected from the group consisting of one or more nonionic ethylenically unsaturated monomers, a cationic ethylenically unsaturated monomer, and an amphiphilic ethylenically unsaturated monomer; and c) an initiator, wherein the batch reactor comprises a stirrer treated by an abrasive polishing technique, or The batch reactor is free of baffles. [5] The method according to claim 4, wherein the abrasive polishing technique is an electropolishing technique. [6] The process according to claim 4, wherein the batch reactor comprises the stirrer treated by the electropolishing technique and the inner walls of the batch reactor are at least partially covered with enamel. [7] Method according to one of claims 4 to 6, characterized bythat the monomer composition comprising the radically polymerizable monomers comprises - at least 5% by weight, preferably at least 20% by weight of the non-ionic monomer of formula (I) R 1 hydrogen or methyl; R 2 and R 3 are independently hydrogen, C1-C5 alkyl or C1-C5 hydroxyalkyl; - at least 5% by weight, preferably at least 20% by weight, particularly preferably 25 to 47% by weight, most preferably 50.5 to 80% by weight, of the cationic monomer of formula (II) R 1 hydrogen or methyl; Z1 is O, NH, NR4, where R4 is C1-C4-alkyl, preferably methyl Y is one of Y0 and Y1 are a C1-C6 alkylene group, optionally substituted by one or more hydroxyl groups, preferably ethylene or propylene, optionally substituted with a hydroxyl group; Y2, Y3, Y5, Y6, Y7 are each independently C1-C6 alkyl, preferably methyl; and Z - a counterion, preferably a halogen, pseudohalogen, acetate or SO4CH3 - ; - 0 to 1.25 wt.%, preferably 0.0001 to 1 wt.%, particularly preferably 0.001 to 0.5 wt.% of the ethylenically unsaturated crosslinker having 2, 3, 4 or 5 ethylenically unsaturated groups; and - optionally further ethylenically unsaturated monomers. [8] Method according to one of claims 4 to 7, characterized by that the monomer composition comprising the radically polymerizable monomers comprises the non-ionic monomer of formula (I) selected from those wherein R1 is hydrogen or methyl, and R 2 and R 3 both are hydrogen, hydrogen and C1-C3 alkyl, hydrogen and hydroxyethyl or both are C1-C3 alkyl, and / or the cationic monomer of formula (II) selected from those wherein R1 is hydrogen or methyl and Z1 is O, NH or NR4, wherein R4 is methyl, Y1 is C2-C6 alkylene, preferably ethylene or propylene, Y5, Y6 and Y7 are all methyl, and Z - is a halogen, most preferably the monomer composition comprising the radically polymerizable monomers comprises at least the nonionic monomer of formula (I) as (meth)acrylamide and the cationic monomer of formula (II) as (meth)acryloylamidopropyltrimethylammonium chloride or (meth)acryloyloxyethyltrimethylammonium chloride. [9] Method according to one of claims 4 to 8, characterized by that the polymeric dispersant is a homopolymer prepared from the cationic monomer of formula (II) R 1 hydrogen or methyl; Z1 is O, NH, NR4, where R4 is C1-C4-alkyl, preferably methyl Y is one of Y0 and Y1 are a C1-C6 alkylene group, optionally substituted by one or several hydroxyl groups, preferably ethylene or propylene, optionally substituted with a hydroxyl group; Y2, Y3, Y5, Y6, Y7 are each independently C1-C6 alkyl, preferably methyl; and Z - a counterion, preferably a halogen, pseudohalogen, acetate or SO4CH3 - . [10] Method according to one of claims 4 to 9, characterized by that the polymeric dispersant is a homopolymer of a (meth)acryloylamidopropyltrimethylammonium salt or a (meth)acryloyloxyethyltrimethylammonium salt. [11] Method according to one of claims 4 to 10, characterized bythat the ratio of the polymeric dispersant to the dispersed 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, particularly 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, in particular in the range of 0.65:1 to 0.9:

1. [12] Use of a batch reactor in a process for preparing a water-in-water polymer dispersion, the process comprising a step of subjecting an aqueous reaction mixture to a radical polymerization to synthesize a dispersed polymer and form the water-in-water polymer dispersion, said aqueous reaction mixture comprising a) a polymeric dispersant; b) a monomer composition comprising radically polymerizable monomers, wherein the radically polymerizable monomers are selected from the group consisting of one or more nonionic ethylenically unsaturated monomers, a cationic ethylenically unsaturated monomer, and an amphiphilic ethylenically unsaturated monomer; and c) an initiator, wherein the batch reactor comprises a stirrer treated by an abrasive polishing technique, or The batch reactor is free of baffles.