Superabsorbent polymers and methods for their preparation

Abstract

Superabsorbent polymers and methods for their preparation are provided, and more particularly, superabsorbent polymers that exhibit improved inhibition of bacterial growth without degrading their water retention capacity, and methods for their preparation are provided.

Description

Technical Field

[0001] Cross-references to related applications

[0002] This application is based on and claims priority to Korean Patent Application Nos. 10-2020-0129643 and 10-2021-0132988, filed on October 7, 2020 and October 7, 2021, respectively, the disclosure of which is incorporated herein by reference in its entirety.

[0003] This invention relates to superabsorbent polymers that exhibit improved bacterial growth inhibition properties without degrading their water retention capacity, and methods for preparing the same. Background Technology

[0004] Superabsorbent polymers (SAPs) are synthetic polymer materials capable of absorbing 500 to 1000 times their own weight in water. Different manufacturers use various names for them, such as SAM (Superabsorbency Material) and AGM (Absorbent Gel Material). Since their initial practical application in hygiene products, SAPs are now widely used not only in hygiene products such as baby diapers, but also in water-retaining soil products for horticulture, waterproofing materials for civil engineering and construction, seedling sheets, preservatives in the food distribution industry, and materials for mud dressings.

[0005] In particular, superabsorbent polymers are most widely used in hygiene products such as baby diapers, adult diapers, or disposable absorbent products. Therefore, when bacteria grow in these hygiene products and disposable absorbent products, there are problems such as the induction of various diseases and secondary odors. Consequently, attempts have been made to introduce various bacterial growth inhibitors or deodorizing or antibacterial functional components into superabsorbent polymers.

[0006] However, in attempts to introduce antimicrobial agents that can inhibit bacterial growth into superabsorbent polymers, it is not easy to select and introduce antimicrobial agent components that exhibit excellent bacterial growth inhibition and deodorization properties, are harmless to humans, and are economically feasible without degrading the basic physical properties of the superabsorbent polymer.

[0007] Therefore, there is a continued need to develop technologies related to superabsorbent polymers that can inhibit bacterial growth without degrading the fundamental physical properties of the superabsorbent polymers. Summary of the Invention

[0008] Technical issues

[0009] Therefore, a superabsorbent polymer that exhibits improved bacterial growth inhibition properties without degrading its water retention capacity is provided, as well as a method for its preparation.

[0010] Technical solution

[0011] According to one embodiment of the present invention,

[0012] Superabsorbent polymers are provided.

[0013] The superabsorbent polymer comprises an acrylic acid-based monomer containing at least partially neutralized acidic groups, a polymeric antimicrobial monomer represented by the following chemical formula 1, and a crosslinked polymer with an internal crosslinking agent:

[0014] [Chemical Formula 1]

[0015]

[0016] In chemical formula 1,

[0017] L is an alkylene group having 1 to 10 carbon atoms.

[0018] R1 to R3 are each independently hydrogen or methyl.

[0019] Of R4 to R6, one is an alkyl group having 6 to 20 carbon atoms, and the remaining are each independently an alkyl group having 1 to 4 carbon atoms.

[0020] X is a halogen.

[0021] According to another embodiment of the present invention,

[0022] A method for preparing superabsorbent polymers is provided, the method comprising the following steps:

[0023] Aqueous gel polymers are formed by crosslinking an acrylic-based monomer containing at least partially neutralized acidic groups and a polymeric antimicrobial monomer represented by Formula 1 in the presence of an internal crosslinking agent and a polymerization initiator; and

[0024] Superabsorbent polymers containing cross-linked polymers are formed by drying, pulverizing, and size sorting aqueous gel polymers.

[0025] Furthermore, according to yet another embodiment of the present invention, a hygiene product comprising the aforementioned superabsorbent polymer is provided.

[0026] Beneficial effects

[0027] The superabsorbent polymer of the present invention can exhibit antibacterial properties that inhibit the growth of bacteria that may be harmful to the human body and may cause secondary odors.

[0028] Specifically, since superabsorbent polymers are prepared by using polymeric antimicrobial monomers with specific structures during the formation of cross-linked polymers, unlike those prepared by using other antimicrobial agents, the superabsorbent polymers can exhibit antimicrobial properties against at least one of Gram-positive and Gram-negative bacteria while maintaining excellent water retention capacity, and the antimicrobial monomers used do not remain in the polymer, which does not cause safety issues in humans due to leakage of antimicrobial agents.

[0029] Therefore, the superabsorbent polymer can be very preferably used in a variety of hygiene products, such as baby diapers and adult diapers that require antibacterial properties against bacteria. Attached Figure Description

[0030] Figure 1 The results of the creep test in Experimental Example 2 of the present invention are shown; and

[0031] Figure 2 and Figure 3 The results of frequency scanning test and amplitude scanning test of Embodiment 3 of the present invention are shown respectively. Detailed Implementation

[0032] The terminology used in this specification is for illustrative purposes only and is not intended to limit the invention. Singular expressions may include plural expressions unless the context otherwise allows. It must be understood that the terms “comprising,” “equipped,” or “having” in this specification are used only to indicate the presence of an effective feature, step, component, or combination thereof, and do not preclude the presence or possible addition of one or more different features, steps, components, or combinations thereof.

[0033] Furthermore, in this invention, when referring to a layer or element being formed "on" or "above" a layer or element, it means that each layer or element is formed directly on the layer or element, or that additional layers or elements may be formed between layers, objects, or substrates.

[0034] This invention can be modified in various ways and can take many forms, with specific examples shown and described in detail below. However, it is not intended to limit the invention to the specific examples, and it must be understood that the invention includes every modification, equivalent, or alternative contained within the spirit and scope of the invention.

[0035] Furthermore, the technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the invention. Additionally, unless the context clearly indicates otherwise, the singular forms used herein are intended to include the plural forms as well.

[0036] At the same time, as used herein, the term "(meth)acrylate" includes both acrylate and methacrylate.

[0037] Furthermore, as used herein, the alkyl group can be linear or branched, and its carbon number is preferably, but not particularly limited to, 1 to 20. According to one embodiment, the alkyl group has 1 to 10 carbon atoms. According to another embodiment, the alkyl group has 1 to 6 carbon atoms. Specific examples of alkyl groups may include, but are not limited to, methyl, ethyl, propyl, n-propyl, isopropyl, butyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methyl-butyl, 1-ethyl-butyl, pentyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, heptyl, n-heptyl, 1-methylhexyl, cyclopentylmethyl, cyclohexylmethyl, octyl, n-octyl, tert-octyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, n-nonyl, 2,2-dimethylheptyl, 1-ethyl-propyl, 1,1-dimethyl-propyl, isohexyl, 2-methylpentyl, 4-methylhexyl, 5-methylhexyl, etc. In this specification, the above description of alkyl groups can be applied to alkylene groups, except that alkylene groups are divalent groups.

[0038] As used herein, the term "polymer" refers to the polymerization state of monomers based on acrylic acid and may encompass the entire range of water content or particle size. Among polymers, those with a water content (moisture content) of about 40% by weight or greater after polymerization and before drying can be called hydrated gel polymers, and particles obtained by pulverizing and drying hydrated gel polymers can be called crosslinked polymers.

[0039] Furthermore, the term "superabsorbent polymer particles" refers to a particulate material containing a crosslinked polymer obtained by polymerizing and crosslinking an acrylic acid-based monomer containing at least partially neutralized acidic groups via an internal crosslinking agent.

[0040] Furthermore, depending on the context, the term "superabsorbent polymer" refers to a cross-linked polymer obtained by polymerizing an acrylic acid-based monomer containing at least partially neutralized acidic groups, or a base polymer in powder form consisting of superabsorbent polymer particles obtained by pulverizing the cross-linked polymer, or a superabsorbent polymer suitable for commercialization prepared by further processing of the cross-linked polymer or base polymer (e.g., surface cross-linking, reassembly of fine particles, drying, pulverizing, size sorting, etc.).

[0041] To ensure the antibacterial and deodorizing properties of conventional superabsorbent polymers, metal compounds with antibacterial functions or organic compounds containing cationic or alcohol functional groups are introduced as additives. However, in this case, the safety of the superabsorbent polymer is reduced, its basic physical properties, such as absorption capacity, are diminished, and there are issues with the durability of the antibacterial properties and leakage of the antibacterial substance.

[0042] For example, attempts have been made to introduce antimicrobial agents, such as copper oxides, containing antimicrobial metal ions like silver, copper, zinc, etc., into superabsorbent polymers. These antimicrobial metal ion-containing components can impart deodorizing properties by disrupting the cell walls of microorganisms, such as bacteria, and killing bacteria with enzymes that may cause unpleasant odors in superabsorbent polymers. However, components containing metal ions are classified as biocidal materials that can kill even microorganisms beneficial to humans. Therefore, when applying superabsorbent polymers to hygiene products such as diapers for children or adults, the introduction of antimicrobial agents containing metal ions should be avoided as much as possible.

[0043] Conventionally, when introducing antimicrobial agents that inhibit bacterial growth into superabsorbent polymers, the primary method is to mix a small amount of the antimicrobial agent with the superabsorbent polymer. However, when using this mixing method, it is difficult to maintain the bacterial growth-inhibiting properties uniformly over time. Furthermore, during the mixing process of the superabsorbent polymer and the antimicrobial agent, this method may result in uneven coating characteristics and separation of the antimicrobial agent components, and also has disadvantages such as the need to install new equipment for mixing.

[0044] Furthermore, various types of bacteria exist, and more than 5,000 types of bacteria have been identified. Specifically, bacteria have various cell morphologies, such as spherical, rod-shaped, and spiral, and their oxygen requirements also differ, thus bacteria are classified into aerobic, facultative aerobic, and anaerobic bacteria. Therefore, it is not easy for a single type of antibacterial agent to possess a physical / chemical mechanism that disrupts the cell membrane / cell wall or denatures the proteins of many different bacteria.

[0045] However, it was found that when the superabsorbent polymer is prepared by polymerizing a monomer having a specific structure and containing a quaternary ammonium salt with an acrylic acid-based monomer, it exhibits a water retention capacity higher than a predetermined level, while also exhibiting antimicrobial properties against at least one of Gram-positive and Gram-negative bacteria, more specifically against both Gram-positive and Gram-negative bacteria, thus completing the present invention.

[0046] Here, “exhibiting antimicrobial properties against specific bacteria” means that the number of bacteria incubated after absorbing artificial urine inoculated with test bacteria into a superabsorbent polymer without antimicrobial material is significantly reduced compared to the number of reference bacteria incubated after absorbing artificial urine inoculated with test bacteria into a superabsorbent polymer to test its antimicrobial properties, and specifically, it means that the antimicrobial rate (%) calculated by the following mathematical equation 1 according to the antimicrobial property test described later is 50% or greater.

[0047] [Mathematical Equation 1]

[0048]

[0049] Where C 样品 This indicates the CFU of bacteria in a superabsorbent polymer containing antimicrobial material after incubation, and C... 参照 This refers to the CFU of bacteria after incubation in a superabsorbent polymer without antimicrobial materials.

[0050] More preferably, “exhibiting antimicrobial properties against specific bacteria” means that the antimicrobial rate (%) calculated by mathematical equation 1 is 60% or greater, 70% or greater, 80% or greater, 90% or greater, 95% or greater, or 99% or greater.

[0051] Gram-positive bacteria are generally defined as bacteria that stain purple using the Gram staining method. The cell walls of Gram-positive bacteria consist of several layers of peptidoglycan, and the purple color does not fade when stained with basic dyes such as crystal violet, even after treatment with ethanol. Bacteria classified as Gram-positive include *Enterococcus faecalis*, *Staphylococcus aureus*, *Streptococcus pneumoniae*, *Enterococcus faecium*, and *Lactobacillus lactis*, among others.

[0052] Furthermore, Gram-negative bacteria generally refer to bacteria that stain red when stained using the Gram staining method. Compared to Gram-positive bacteria, Gram-negative bacteria have an outer membrane composed of lipopolysaccharides, lipoproteins, and other complex polymers, rather than a cell wall with a relatively small amount of peptidoglycan. Therefore, when Gram-negative bacteria are stained with a basic dye such as crystal violet and then treated with ethanol, they are decolorized, and when reverse-stained with a red dye such as safranin, they turn red. Bacteria classified as Gram-negative include *Proteus mirabilis*, *Escherichia coli*, *Salmonella typhi*, *Pseudomonas aeruginosa*, and *Vibrio cholerae*, among others.

[0053] Since Gram-positive and Gram-negative bacteria can cause a variety of diseases upon contact and can also lead to secondary infections in critically ill patients with weakened immune systems, it is preferable to use a single antimicrobial agent to achieve antimicrobial properties against both Gram-positive and Gram-negative bacteria.

[0054] Meanwhile, according to one embodiment, the superabsorbent polymer contains repeating units derived from the antimicrobial monomer represented by Formula 1 in the main chain constituting the crosslinked polymer, thereby exhibiting antimicrobial properties against at least one of Gram-positive and Gram-negative bacteria. Specifically, due to the quaternary ammonium salt moiety having an alkyl group having a predetermined number or more carbon atoms in the crosslinked polymer contained in the superabsorbent polymer, the ammonium cation of the quaternary ammonium salt is electrostatically adsorbed onto the cell wall of Gram-positive or Gram-negative bacteria, and then physically and chemically disrupts the bacterial cell surface structure through interaction with the hydrophobic alkyl group of the quaternary ammonium salt. Therefore, the superabsorbent polymer can exhibit antimicrobial properties.

[0055] More specifically, superabsorbent polymers can exhibit antimicrobial properties against one or more types of bacteria classified as Gram-positive. Alternatively, superabsorbent polymers can exhibit antimicrobial properties against one or more types of bacteria classified as Gram-negative. Or, superabsorbent polymers can exhibit antimicrobial properties against one or more types of bacteria classified as Gram-negative and one or more types of bacteria classified as Gram-positive.

[0056] Furthermore, superabsorbent polymers can exhibit excellent antibacterial properties as described above while also displaying a centrifuge retention capacity (CRC) of 29 g / g to 50 g / g. In this respect, when the CRC of a superabsorbent polymer is less than 29 g / g, its ability to retain liquid after absorption is reduced, and therefore, superabsorbent polymers are unsuitable for use in hygiene products. When the CRC of a superabsorbent polymer is greater than 50 g / g, this is also unsuitable because the absorption rate under pressure (which has a trade-off with the CRC) may decrease.

[0057] Furthermore, in superabsorbent polymers, the antimicrobial agent forms the backbone of the cross-linked polymer together with the acrylic acid-based monomer, rather than in a simple mixed form. Therefore, it is not retained in the superabsorbent polymer as an antimicrobial monomer compound. Thus, there is no need to worry about antimicrobial agent leakage even over time.

[0058] The superabsorbent polymer and its preparation method will be described in more detail below according to specific embodiments of the present invention.

[0059] Superabsorbent polymers

[0060] Specifically, the superabsorbent polymer according to one embodiment of the present invention is characterized by comprising a crosslinked polymer containing an acrylic acid-based monomer with at least partially neutralized acidic groups, a polymeric antimicrobial monomer, and an internal crosslinking agent.

[0061] The polymeric antimicrobial monomers include compounds represented by the following chemical formula 1:

[0062] [Chemical Formula 1]

[0063]

[0064] In chemical formula 1,

[0065] L is an alkylene group having 1 to 10 carbon atoms.

[0066] R1 to R3 are each independently hydrogen or methyl.

[0067] Of R4 to R6, one is an alkyl group having 6 to 20 carbon atoms, and the remaining are each independently an alkyl group having 1 to 4 carbon atoms.

[0068] X is a halogen.

[0069] In this regard, the cross-linked polymer, produced by the cross-linking polymerization of acrylic acid-based monomers containing at least partially neutralized acidic groups and polymeric antimicrobial monomers in the presence of an internal cross-linking agent, possesses a three-dimensional network structure, wherein the main chain formed by the polymerization of monomers is cross-linked by the internal cross-linking agent. Therefore, the polymeric antimicrobial monomer does not exist as a separate compound in the superabsorbent polymer, but rather as a repeating unit constituting the main chain, and thus it does not leak over time. Consequently, the antimicrobial properties of the superabsorbent polymer can be continuously maintained.

[0070] Meanwhile, the monomer based on acrylic acid is a compound represented by the following chemical formula 1:

[0071] [Chemical Formula 2]

[0072] R-COOM'

[0073] In chemical formula 2,

[0074] R is an alkyl group containing unsaturated bonds and having 2 to 5 carbon atoms, and

[0075] M' can be a hydrogen atom, a monovalent or divalent metal, an ammonium group, or an organic amine salt.

[0076] Preferably, the monomer may include one or more of the following: (meth)acrylic acid and its monovalent (basic) metal salt, its divalent metal salt, its ammonium salt and its organic amine salt.

[0077] As described, when (meth)acrylic acid and / or its salts can be used as acrylic acid-based monomers, it is advantageous to obtain superabsorbent polymers with improved absorption rates.

[0078] Here, the acrylic acid-based monomers may have at least partially neutralized acidic groups. Preferably, those partially neutralized with alkaline substances such as sodium hydroxide, potassium hydroxide, ammonium hydroxide, etc., can be used as monomers. In this regard, the degree of neutralization of the acrylic acid-based monomers can be 40 mol% to 95 mol%, or 40 mol% to 80 mol%, or 45 mol% to 75 mol%. The range of neutralization can vary depending on the final physical properties. However, excessively high neutralization causes the neutralized monomers to precipitate, and therefore polymerization may not easily occur, while excessively low neutralization not only greatly degrades the polymer's absorbency but also imparts unmanageable properties to the polymer, such as the properties of elastic rubber.

[0079] Meanwhile, the polymeric antibacterial monomer represented by chemical formula 1 comprises: a linking group (L) connected to an acrylic acid group, said linking group (L) being polymerizable with the acrylic acid monomer; and a quaternary ammonium cation having three end substituents R4, R5 and R6.

[0080] In this respect, the linking group (L) can be a linear alkylene group having 1 to 10 carbon atoms. More specifically, L can be a linear alkylene group having 1 to 5 carbon atoms, such as methylene, ethylene, or propylene.

[0081] Furthermore, the quaternary ammonium cation of the polymeric antimicrobial monomer is substituted with one of the three terminal substituents, R4, R5, and R6, which is an alkyl group having 6 to 20 carbon atoms. More specifically, one of the R4, R5, and R6 substituents is a linear, i.e., a straight-chain alkyl group having 6 to 20 carbon atoms. In this regard, when two of the R4, R5, and R6 substituents are alkyl groups having 1 to 4 carbon atoms, and the other is an alkyl group having 5 or fewer carbon atoms, there is a problem that the antimicrobial properties may not be achieved. When one of the R4, R5, and R6 substituents is an alkyl group having more than 20 carbon atoms, the starting material used to prepare the monomer cannot be dissolved in the solvent, and therefore the synthesis itself is impossible.

[0082] Furthermore, in chemical formula 1, one of R4 to R6 is an alkyl group having 5 to 20 carbon atoms, and the others are each independently methyl or ethyl.

[0083] More specifically, R1 is hydrogen or methyl, R2 and R3 are hydrogen, one of R4 to R6 is an alkyl group having 5 to 20 carbon atoms, and the remainder are each independently methyl or ethyl; or

[0084] R1 to R3 are all hydrogen, one of R4 to R6 is an alkyl group having 5 to 20 carbon atoms, and the others are each independently methyl or ethyl.

[0085] Furthermore, in the R4, R5, and R6 substituents, the two substituents other than the alkyl group having 5 to 20 carbon atoms can be identical to each other.

[0086] Preferably, in Formula 1, one of R4, R5, and R6 may have 6 or more, 7 or more, or 8 or more carbon atoms, and 20 or fewer, 18 or fewer, 16 or fewer, 14 or fewer, or 12 or fewer carbon atoms. Antimicrobial copolymers containing the first repeating unit represented by Formula 1 may exhibit superior antimicrobial properties.

[0087] For example, R1 can be methyl, R2 and R3 can be hydrogen, and one of R4, R5 and R6 can be an alkyl group having 6 to 16 carbon atoms, and the remainder can each be methyl or ethyl independently. Antimicrobial copolymers containing a first repeating unit having such a structure can exhibit excellent antimicrobial properties against Gram-positive bacteria and at least one of them, more specifically against all Gram-positive and Gram-negative bacteria.

[0088] Furthermore, for example, R1 can be methyl, R2 and R3 can be hydrogen, and one of R4 to R6 can be an alkyl group having 10 to 14 carbon atoms, and the remainder can be methyl. When the superabsorbent polymer according to one embodiment comprises a crosslinked polymer achieved by a polymeric antimicrobial monomer having such a structure, the superabsorbent polymer can exhibit excellent antimicrobial properties against Gram-positive bacteria and at least one of Gram-positive bacteria, more specifically against all Gram-positive and Gram-negative bacteria, even if the polymeric antimicrobial monomer in the crosslinked polymer is included in small amounts, for example, 0.1 parts by weight or more and 5 parts by weight or less relative to 100 parts by weight of acrylic acid-based monomer.

[0089] Furthermore, in chemical formula 1, X can be a halogen, preferably chlorine (Cl) or bromine (Br).

[0090] Furthermore, the polymeric antimicrobial monomer can be a compound represented by any of the following chemical formulas 1-1 to 1-4:

[0091]

[0092] In chemical formulas 1-1 to 1-4,

[0093] a is an integer from 2 to 9.

[0094] b is an integer from 2 to 8, and

[0095] X is bromine or chlorine.

[0096] More specifically, in chemical formulas 1-1 to 1-4, a can be 2, 3, 4, 5, 6, 7, 8, or 9, and b can be 2, 3, 4, 5, 6, 7, or 8. Preferably, a and b can each be independently 4, 5, or 6.

[0097] For example, the polymeric antimicrobial monomer can be selected from any of the following compounds:

[0098]

[0099] In cross-linked polymers, such polymeric antimicrobial monomers are included in an amount of 0.1 to 20 parts by weight relative to 100 parts by weight of acrylic-based monomers. When the polymeric antimicrobial monomer is included in an amount of less than 0.1 parts by weight relative to 100 parts by weight of acrylic-based monomers, it is difficult to achieve sufficient antimicrobial and deodorizing properties. When the polymeric antimicrobial monomer is included in an amount of more than 20 parts by weight relative to 100 parts by weight of acrylic-based monomers, it may damage the user's normal cells and microorganisms, which is therefore unsuitable in terms of human safety, and there is a problem of deterioration of water retention capacity (a general physical property of superabsorbent polymers). For example, in cross-linked polymers, polymeric antimicrobial monomers may be included in amounts of 0.1 parts by weight or more, 0.2 parts by weight or more, 0.3 parts by weight or more, and 20 parts by weight or less, 15 parts by weight or less, 10 parts by weight or less, or 5 parts by weight or less relative to 100 parts by weight of acrylic-based monomers.

[0100] In this regard, in the crosslinked polymer, the polymeric antimicrobial monomer can be included in an amount of 0.1 to 20 parts by weight relative to 100 parts by weight of the acrylic-based monomer. This means that during the preparation of the crosslinked polymer, the polymeric antimicrobial monomer is used in an amount of 0.1 to 20 parts by weight relative to 100 parts by weight of the acrylic-based monomer. In other words, when the residual monomer of the superabsorbent polymer was examined, no leakage of the antimicrobial monomer was observed, indicating that the entire amount of the antimicrobial monomer was used in the polymerization with the acrylic-based monomer, which can be confirmed in the experimental examples described later.

[0101] For example, a superabsorbent polymer containing, in a crosslinked polymer, an antimicrobial monomer of polymeric form comprising, in an amount of 0.1 to 1.0 parts by weight relative to 100 parts by weight of an acrylic-based monomer, wherein one of R4 to R6 in Formula 1 is an alkyl group having 10 to 20 carbon atoms and the remainder is a methyl group, can exhibit a 30-minute centrifugation retention capacity (CRC) of 40 g / g to 50 g / g against physiological saline (0.9% sodium chloride aqueous solution) as measured according to EDANA standard WSP 241.3, while exhibiting excellent antimicrobial properties against Gram-positive bacteria and at least one of Gram-positive bacteria, preferably against all Gram-positive and Gram-negative bacteria, i.e., an antimicrobial rate of 99% or greater as calculated by mathematical equation 1.

[0102] Furthermore, as used herein, the term "internal crosslinking agent" is used to distinguish it from the surface crosslinking agent that causes the surface crosslinking of the superabsorbent polymer particles described later, and serves to polymerize them by crosslinking the unsaturated bonds of the acrylic-based monomers. The crosslinking in the above steps is carried out independently of surface crosslinking or internal crosslinking. However, when the surface crosslinking process of the superabsorbent polymer particles, described later, is performed, the final superabsorbent polymer particles have a crosslinked structure on their surface due to the surface crosslinking agent, and a crosslinked structure inside due to the internal crosslinking agent.

[0103] Any compound can be used as an internal crosslinking agent, as long as it enables crosslinking to be introduced during the polymerization of acrylic acid-based monomers. Non-limiting examples of internal crosslinking agents may include multifunctional crosslinking agents, such as N,N'-methylenebisacrylamide, trimethylolpropane tri(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol (meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polypropylene glycol (meth)acrylate, butanediol di(meth)acrylate, butylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, hexanediol di(meth)acrylate, triethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, dipentaerythritol pentaacrylate, glycerol tri(meth)acrylate, pentaerythritol tetraacrylate, triarylamine, ethylene glycol diglycidyl ether, propylene glycol, glycerol, or ethylene carbonate, which may be used alone or in combination of two or more thereof, but are not limited thereto. Ethylene glycol diglycidyl ether may be preferred.

[0104] Crosslinking polymerization of acrylic acid monomers in the presence of an internal crosslinking agent can be carried out by thermal polymerization, photopolymerization, or mixed polymerization in the presence of a polymerization initiator, and if necessary, a thickener, plasticizer, preservation stabilizer, antioxidant, etc., which will be described in detail later.

[0105] Furthermore, superabsorbent polymers can be in the form of particles with a particle size of 850 μm or smaller (e.g., about 150 μm to 850 μm). In this regard, the particle size can be measured according to the European Disposables and Nonwovens Association (EDANA) standard WSP 220.3. Here, when the superabsorbent polymer contains a large number of fine particles with a particle size smaller than 150 μm, the general physical properties of the superabsorbent polymer may deteriorate, which is not preferred.

[0106] Simultaneously, the superabsorbent polymer may also include a surface crosslinking layer formed on the crosslinked polymer by further crosslinking the crosslinked polymer via a surface crosslinking agent. This is to increase the surface crosslinking density of the superabsorbent polymer particles. As described, when the superabsorbent polymer particles also include a surface crosslinking layer, they may have a structure in which the external crosslinking density is higher than the internal crosslinking density.

[0107] As a surface crosslinking agent, surface crosslinking agents already used in the preparation of superabsorbent polymers can be used without particular limitation. For example, the surface crosslinking agent may include: one or more polyols selected from ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,2-hexanediol, 1,3-hexanediol, 2-methyl-1,3-propanediol, 2,5-hexanediol, 2-methyl-1,3-pentanediol, 2-methyl-2,4-pentanediol, tripropylene glycol, and glycerol; one or more carbonate-based compounds selected from ethylene carbonate, propylene carbonate, and glycerol carbonate; and epoxy compounds, such as ethylene glycol diglycidyl ether, etc. Azoline compounds, for example Alzolidinediones, etc.; polyamine compounds; Azoline compounds; monozoline compounds azole ketone compounds, di azole ketone compounds or more Alzolidinediones; or cyclic urea compounds; etc.

[0108] Specifically, as a surface crosslinking agent, one or more, two or more, or three or more of the above-mentioned surface crosslinking agents can be used, for example, ethylene carbonate-propylene carbonate (ECPC), propylene glycol and / or glycerol carbonate can be used.

[0109] Furthermore, the centrifugal retention capacity (CRC) of the aforementioned superabsorbent polymers, as measured according to EDANA standard WSP 241.3, can be in the range of 29 g / g or greater, 33 g / g or greater, 38 g / g or greater, or 40 g / g or greater, and 50 g / g or less, or 48 g / g or less, 46 g / g or less, or 44 g / g or less.

[0110] Furthermore, according to creep testing, the aforementioned superabsorbent polymer can have a maximum strain of 0.30% to 1.50% and a recovery rate of 70% to 100%. Detailed methods for creep testing will be described in the following examples. Preferably, the maximum strain of the aforementioned superabsorbent polymer according to creep testing can be 0.31% or greater, 0.32% or greater, 0.33% or greater, 0.34% or greater, 0.35% or greater, 0.36% or greater, 0.37% or greater, 0.38% or greater, 0.39% or greater, 0.40% or greater, 0.41% or greater, 0.42% or greater, or 0.43% or greater, and 1.45% or less, 1.40% or less, 1.35% or less, 1.30% or less, 1.25% or less, or 1.23% or less. Preferably, the recovery rate of the superabsorbent polymer according to the creep test can be 71% or greater, 72% or greater, 73% or greater, 74% or greater, 75% or greater, 76% or greater, 77% or greater, 78% or greater, 79% or greater, or 80% or greater.

[0111] Furthermore, the gel strength of the aforementioned superabsorbent polymer can be from 1500 Pa to 5000 Pa. Detailed methods for measuring gel strength will be described in the following examples. Preferably, the gel strength of the aforementioned superabsorbent polymer can be 1600 Pa or greater, 1617 Pa or greater, 1700 Pa or greater, 1800 Pa or greater, 1900 Pa or greater, or 2000 Pa or greater, and 4900 Pa or less, 4800 Pa or less, 4700 Pa or less, 4600 Pa or less, 4545 Pa or less, 4500 Pa or less, 4400 Pa or less, 4399 Pa or less, 4300 Pa or less, 4200 Pa or less, 4100 Pa or less, 4000 Pa or less, 3900 Pa or less, 3899 Pa or less, or 3800 Pa or less.

[0112] Furthermore, the permeability of the aforementioned superabsorbent polymer can be between 70 seconds and 150 seconds. Detailed methods for measuring the permeability will be described in the following embodiments. Preferably, the permeability of the aforementioned superabsorbent polymer can be 71 seconds or more, 72 seconds or more, 73 seconds or more, 74 seconds or more, 75 seconds or more, 76 seconds or more, 77 seconds or more, 78 seconds or more, 79 seconds or more, 80 seconds or more, 81 seconds or more, 82 seconds or more, 83 seconds or more, or 84 seconds or more, and 145 seconds or less, 140 seconds or less, 135 seconds or less, 130 seconds or less, 125 seconds or less, 120 seconds or less, 115 seconds or less, 110 seconds or less, 105 seconds or less, or 100 seconds or less.

[0113] Furthermore, superabsorbent polymers can exhibit antimicrobial properties against all Gram-negative and Gram-positive bacteria. In this regard, the Gram-negative and Gram-positive bacteria against which superabsorbent polymers exhibit antimicrobial properties can be Proteus mirabilis or Escherichia coli and Enterococcus faecalis, respectively, but are not limited to these.

[0114] Methods for preparing superabsorbent polymers

[0115] Meanwhile, superabsorbent polymers can be prepared by the following preparation method, which includes the following steps:

[0116] Aqueous gel polymers are formed by crosslinking an acrylic-based monomer containing at least partially neutralized acidic groups and a polymeric antimicrobial monomer represented by Formula 1 in the presence of an internal crosslinking agent and a polymerization initiator; and

[0117] Superabsorbent polymers containing cross-linked polymers are formed by drying, pulverizing, and size sorting aqueous gel polymers.

[0118] The superabsorbent polymer prepared by the method can exhibit a 30-minute centrifugation retention capacity (CRC) of 29 g / g to 50 g / g against physiological saline (0.9 wt% sodium chloride aqueous solution) as measured according to EDANA standard WSP 241.3, while also exhibiting the antibacterial properties against at least one of Gram-positive and Gram-negative bacteria as described above.

[0119] First, step 1 is a step of forming an aqueous gel polymer by crosslinking polymerization of an acrylic-based monomer and a polymeric antimicrobial monomer containing at least partially neutralized acidic groups in the presence of an internal crosslinking agent and a polymerization initiator.

[0120] This step may include preparing a monomer composition by mixing an acrylic-based monomer, an internal crosslinking agent, and a polymerization initiator, and forming an aqueous gel polymer by performing thermal polymerization or photopolymerization of the monomer composition. In this regard, the descriptions of the acrylic-based monomer and the internal crosslinking agent can be found above.

[0121] In the monomer composition, an internal crosslinking agent is included in an amount of 0.01 to 1 part by weight relative to 100 parts by weight of the acrylic-based monomer, thereby crosslinking the polymer. When the amount of the internal crosslinking agent is less than 0.01 parts by weight, the improvement effect attributed to crosslinking is not significant. When the amount of the internal crosslinking agent is greater than 1 part by weight, the absorption rate of the superabsorbent polymer may decrease. More specifically, the internal crosslinking agent may be included in an amount of 0.05 parts by weight or more, or 0.1 parts by weight or more, and 0.5 parts by weight or less, or 0.3 parts by weight or less, relative to 100 parts by weight of the acrylic-based monomer.

[0122] Furthermore, the polymerization initiator can be appropriately selected based on the polymerization method. When using thermal polymerization, a thermal polymerization initiator is used. When using photopolymerization, a photopolymerization initiator is used. When using a hybrid polymerization method (using both heat and light), both a thermal polymerization initiator and a photopolymerization initiator are used. However, even when using photopolymerization, a certain amount of heat is generated by light irradiation, such as UV irradiation, and a certain amount of heat is also generated with the exothermic polymerization reaction. Therefore, a thermal polymerization initiator can also be used.

[0123] As a photopolymerization initiator, any compound capable of forming free radicals by light, such as UV, can be used without any restrictions in terms of composition.

[0124] For example, one or more of the following can be used as photopolymerization initiators: benzoin ether, dialkyl acetophenone, hydroxyalkyl ketone, phenyl glyoxylate, benzyl dimethyl ketal, acylphosphine, and α-amino ketone. Specific examples of acylphosphine may include diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, ethyl (2,4,6-trimethylbenzoyl)phenylphosphine sulfate, etc. Many more different photopolymerization initiators are fully disclosed on page 115 of "UV Coatings: Basics, Recent Developments and New Application" by Reinhold Schwalm (Elsevier, 2007), however, it is not limited to the examples mentioned above.

[0125] The photopolymerization initiator may be included in an amount from 0.001 parts by weight to 1 part by weight relative to 100 parts by weight of the acrylic acid-based monomer. When the amount of photopolymerization initiator is less than 0.001 parts by weight, the polymerization rate may be slower, and when the amount of photopolymerization initiator is greater than 1 part by weight, the molecular weight of the superabsorbent polymer becomes smaller and its physical properties may become inhomogeneous. More specifically, the photopolymerization initiator may be included in an amount of 0.005 parts by weight or more, or 0.01 parts by weight or more, or 0.1 parts by weight or more, and 0.5 parts by weight or less, or 0.3 parts by weight or less relative to 100 parts by weight of the acrylic acid-based monomer.

[0126] Furthermore, when a thermal polymerization initiator is also included as the polymerization initiator, one or more of the following can be used as the thermal polymerization initiator: persulfate-based initiators, azo-based initiators, hydrogen peroxide, and ascorbic acid. Specific examples of persulfate-based initiators may include sodium persulfate (Na2S2O8), potassium persulfate (K2S2O8), ammonium persulfate ((NH4)2S2O8), etc., and examples of azo-based initiators may include 2,2-azobis-(2-amidinylpropane) dihydrochloride, 2,2-azobis-(N,N-dimethylene)isobutyramidine dihydrochloride, 2-(carbamoylazo)isobutyronitrile, 2,2-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride, 4,4-azobis-(4-cyanopentanoic acid), etc. Many more different thermal polymerization initiators are fully disclosed on page 203 of "Principle of Polymerization" by Odian (Wiley, 1981); however, thermal polymerization initiators are not limited to the examples mentioned above.

[0127] The thermal polymerization initiator can be included in an amount from 0.001 parts by weight to 1 part by weight relative to 100 parts by weight of the acrylic-based monomer. When the amount of thermal polymerization initiator is less than 0.001 parts by weight, almost no further thermal polymerization occurs, and therefore the effect of adding the thermal polymerization initiator may be insignificant. When the amount of thermal polymerization initiator is greater than 1 part by weight, the molecular weight of the superabsorbent polymer may become lower and its physical properties may become non-uniform. More specifically, the thermal polymerization initiator can be included in an amount of 0.005 parts by weight or more, or 0.01 parts by weight or more, or 0.1 parts by weight or more, and 0.5 parts by weight or less, or 0.3 parts by weight or less relative to 100 parts by weight of the acrylic-based monomer.

[0128] During crosslinking polymerization, if necessary, the monomer composition may contain one or more additives in addition to the polymerization initiator, such as surfactants, thickeners, plasticizers, preservation stabilizers, antioxidants, etc.

[0129] The monomer composition comprising acrylic acid-based monomers, polymeric antimicrobial monomers, and internal crosslinking agents, and optionally photopolymerization initiators and additives, may be in a solvent-soluble form.

[0130] As a suitable solvent, any solvent can be used without limitation in terms of composition, as long as it can dissolve the above components. For example, a combination of one or more of the following can be used: water, ethanol, ethylene glycol, diethylene glycol, triethylene glycol, 1,4-butanediol, propylene glycol, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, methyl ethyl ketone, acetone, methyl pentyl ketone, cyclohexanone, cyclopentanone, diethylene glycol monomethyl ether, diethylene glycol ethyl ether, toluene, xylene, butyrolactone, carbitol, methyl cellosolve acetate, and N,N-dimethylacetamide. The solvent can be included in the remaining amount excluding the above components relative to the total amount of the monomer composition.

[0131] In addition, when using a water-soluble solvent such as water as the solvent and using a terpene-based compound that is not soluble in water as the polymeric antimicrobial monomer, a surfactant may be added in an amount of 10 parts by weight or less relative to 100 parts by weight of the polymeric antimicrobial monomer to improve solubility.

[0132] Meanwhile, there are no particular restrictions on the composition of the method for forming aqueous gel polymers by photopolymerization of monomer compositions, as long as it is a commonly used polymerization method.

[0133] Specifically, photopolymerization can be carried out by irradiating UV light at temperatures of 60°C to 90°C, or 70°C to 80°C, with an intensity of 3mW to 30mW, or 10mW to 20mW. When photopolymerization can be carried out under these conditions, cross-linked polymers can be formed with high polymerization efficiency.

[0134] Furthermore, when photopolymerization is performed, it can be carried out in a reactor equipped with a movable conveyor belt, but the above-described polymerization method is merely an example, and the present disclosure is not limited to the above-described polymerization method.

[0135] Furthermore, as mentioned above, when photopolymerization is carried out in a reactor equipped with a movable conveyor belt, the resulting aqueous gel polymer is typically a sheet-like aqueous gel polymer having the width of the belt. In this case, the thickness of the polymer sheet can vary depending on the concentration and feed rate of the monomer composition fed therein. Generally, it is preferable to supply the monomer composition such that a sheet polymer with a thickness of about 0.5 cm to about 5 cm can be obtained. When the monomer composition is supplied to such a degree that the thickness of the sheet polymer becomes too thin, it is undesirable due to low production efficiency, and when the thickness of the sheet polymer is greater than 5 cm, the polymerization reaction may not occur uniformly across the entire thickness due to the excessive thickness.

[0136] Furthermore, the water content of the aqueous gel polymer obtained by the above method can be from about 40% to about 80% by weight relative to the total weight of the aqueous gel polymer. Meanwhile, as used herein, "water content" refers to the weight of water relative to the total weight of the aqueous gel polymer, which can be obtained by subtracting the weight of the dried polymer from the weight of the aqueous gel polymer. Specifically, the water content can be defined as a value calculated by measuring the weight loss due to the evaporation of moisture in the polymer during the drying process by raising the temperature of the polymer via infrared heating. The water content is measured under the following drying conditions: the temperature is raised from room temperature to about 180°C, then maintained at 180°C, and the total drying time is set to 20 minutes, including 5 minutes for the heating step.

[0137] Additionally, after preparing the aqueous gel polymer, and before subsequent drying and pulverizing processes, the prepared aqueous gel polymer can optionally be coarsely pulverized.

[0138] The coarse grinding process is used to improve the drying efficiency in the subsequent drying process and to control the particle size of the produced superabsorbent polymer powder. In this regard, the pulverizer used herein is not limited by its configuration, and specifically, it may include any of the following selected from vertical pulverizers, turbo cutters, turbo mills, rotary cuttermills, cutter mills, disc mills, shred crushers, crushers, meat grinders, and disc cutters, but is not limited to the examples mentioned above.

[0139] A coarse grinding process can be performed, for example, to reduce the particle size of the hydrated gel polymer to approximately 2 mm to approximately 10 mm. Grinding the hydrated gel polymer to a particle size smaller than 2 mm is technically difficult due to the high water content of the polymer, and agglomeration of the ground particles may occur. Furthermore, when the hydrated gel polymer is ground to a particle size larger than 10 mm, the effect on improving the efficiency of subsequent drying steps may not be significant.

[0140] Additionally, after preparing the aqueous gel polymer, and before subsequent drying and pulverizing processes, the prepared aqueous gel polymer can optionally be coarsely pulverized.

[0141] The coarse grinding process is used to improve the drying efficiency in the subsequent drying process and to control the particle size of the final produced superabsorbent polymer powder. In this regard, the pulverizer used herein is not limited by its configuration, and specifically, it may include any of the following selected from vertical pulverizers, turbo cutters, turbo mills, rotary cuttermills, cutter mills, disc mills, shred crushers, crushers, meat grinders, and disc cutters, but is not limited to the examples mentioned above.

[0142] A coarse grinding process can be performed, for example, to reduce the particle size of the hydrated gel polymer to approximately 2 mm to approximately 10 mm. Grinding the hydrated gel polymer to a particle size smaller than 2 mm is technically difficult due to the high water content of the polymer, and agglomeration of the ground particles may occur. Furthermore, when the hydrated gel polymer is ground to a particle size larger than 10 mm, the effect on improving the efficiency of subsequent drying steps may not be significant.

[0143] Next, step 2 is a step of forming a superabsorbent polymer containing a crosslinked polymer by drying, pulverizing and size sorting the aqueous gel polymer prepared in step 1.

[0144] The drying method can be selected and used without any restrictions on its composition, as long as it is generally used for drying aqueous gel polymers. Specifically, the drying step can be carried out by methods such as hot air supply, infrared irradiation, microwave irradiation, ultraviolet irradiation, etc.

[0145] Specifically, drying can be carried out at a temperature of about 150°C to about 250°C. When the drying temperature is below 150°C, the drying time becomes too long and may degrade the physical properties of the final superabsorbent polymer. When the drying temperature is above 250°C, only the polymer surface is over-dried, which may generate fine particles during the subsequent pulverization process and may also degrade the physical properties of the final superabsorbent polymer. Therefore, drying can preferably be carried out at a temperature of 150°C or higher, or 160°C or higher, and 200°C or lower, or 180°C or lower.

[0146] Meanwhile, considering process efficiency, the drying time can be from about 20 minutes to about 90 minutes, but is not limited to this.

[0147] The water content of the polymer after such a drying step can be from about 5% by weight to about 10% by weight.

[0148] After the drying process, a pulverizing process is carried out.

[0149] The pulverization process can be performed to reduce the particle size of the polymer powder (i.e., the superabsorbent polymer) to approximately 150 μm to approximately 850 μm. Pulverizers used for pulverizing to such particle sizes can specifically include pin mills, hammer mills, spiral mills, roller mills, disc mills, jogging mills, etc., but the invention is not limited to the examples described above.

[0150] After the above pulverization steps, in order to control the physical properties of the final superabsorbent polymer powder, the pulverized polymer powder can be further subjected to a size sorting process based on particle size.

[0151] Furthermore, polymers with particle sizes ranging from approximately 150 μm to approximately 850 μm are sorted. Only polymers with this particle size can be used as base polymers in the surface crosslinking reaction step and ultimately commercialized.

[0152] The superabsorbent polymer produced by the above process can be in the form of a fine powder comprising a cross-linked polymer obtained by cross-linking an acrylic-based monomer and a polymeric antimicrobial monomer via an internal cross-linking agent. Specifically, the superabsorbent polymer can be in the form of a fine powder with a particle size of 150 μm to 850 μm.

[0153] Next, the process may include a step of cross-linking the surface of the superabsorbent polymer prepared in step 2 by heat treatment in the presence of a surface cross-linking agent.

[0154] Surface crosslinking is a step that increases the crosslinking density near the surface of a superabsorbent polymer relative to its internal crosslinking density. Typically, a surface crosslinking agent is applied to the surface of the polymer. Therefore, the reaction occurs on the surface of the polymer particles, which improves the crosslinking properties on the surface of the particles without significantly affecting the interior of the particles. Consequently, surface-crosslinked superabsorbent polymers have a higher degree of crosslinking near the surface than inside.

[0155] Such a surface crosslinking agent can be used in an amount from about 0.001 parts by weight to about 5 parts by weight relative to 100 parts by weight of the superabsorbent polymer. For example, the surface crosslinking agent can be used in an amount of about 0.005 parts by weight or more, 0.01 parts by weight or more, or 0.05 parts by weight or more, and 5 parts by weight or less, 4 parts by weight or less, or 3 parts by weight or less relative to 100 parts by weight of the superabsorbent polymer. Superabsorbent polymers exhibiting excellent overall absorption properties can be prepared by controlling the amount of surface crosslinking agent within the above-mentioned range.

[0156] Furthermore, there are no limitations on the composition of the method for mixing the surface crosslinking agent with the superabsorbent polymer. For example, methods such as feeding the surface crosslinking agent and the superabsorbent polymer into a reactor and mixing them together, spraying the surface crosslinking agent onto the superabsorbent polymer, or mixing the superabsorbent polymer and the surface crosslinking agent while feeding them into a continuously operating mixer can be used.

[0157] In addition to the surface crosslinking agent, water and alcohol are separately mixed together and added in the form of a surface crosslinking solution. The advantage of adding water and alcohol is that the surface crosslinking agent can be uniformly dispersed in the superabsorbent polymer powder. Here, for the purpose of simultaneously causing uniform dispersion of the surface crosslinking agent, preventing agglomeration of the superabsorbent polymer powder, and optimizing the surface penetration depth of the crosslinking agent, water and alcohol can be added in an amount of about 5 to about 12 parts by weight relative to 100 parts by weight of the polymer.

[0158] Surface crosslinking can be carried out by heating the superabsorbent polymer powder to which a surface crosslinking agent has been added at a temperature of about 80°C to about 220°C for about 15 minutes to about 100 minutes. When the crosslinking reaction temperature is below 80°C, sufficient surface crosslinking may not occur, and when the crosslinking reaction temperature is above 220°C, excessive surface crosslinking may occur. Furthermore, when the crosslinking reaction time is less than 15 minutes, sufficient crosslinking may not occur, and when the crosslinking reaction time exceeds 100 minutes, the crosslinking density on the particle surface increases excessively due to excessive surface crosslinking, leading to deterioration of physical properties. More specifically, the surface crosslinking reaction can be carried out by heating at a temperature of 120°C or higher, or 140°C or higher and 200°C or lower, or 180°C or lower for 20 minutes or longer, or 40 minutes or longer and 70 minutes or less, or 60 minutes or less.

[0159] There are no particular limitations on the method used to raise the temperature of the additional crosslinking reaction. Heating can be carried out by providing a heating medium or by directly providing a heat source. In this regard, suitable types of heating media can be hot fluids such as steam, hot air, hot oil, etc. However, the invention is not limited to this. The temperature of the provided heating medium can be appropriately controlled by considering the type of heating medium, the heating rate, and the target temperature. Meanwhile, as a directly provided heat source, an electric heater or a gas heater can be used, but the invention is not limited to these examples.

[0160] Meanwhile, a composition comprising the aforementioned superabsorbent polymer is provided.

[0161] In addition, articles comprising the aforementioned superabsorbent polymer are provided.

[0162] The articles may be selected from one or more of the following: absorbent articles; hygiene products; water-retaining soil products; waterproofing materials for civil engineering and construction; seedling sheets; preservatives; mud dressing materials; electrical insulators; and oral, dental, cosmetic, or skin articles.

[0163] In this regard, hygiene products containing superabsorbent polymers can include, for example, children's diapers, adult diapers, sanitary napkins, etc. In particular, superabsorbent polymers can be preferably applied to adult diapers where secondary odor caused by bacterial growth is particularly problematic. Such hygiene products can have the same configuration as ordinary hygiene products, except that the absorbent contains the aforementioned superabsorbent polymer of one embodiment.

[0164] Preferred embodiments are provided below to better understand the invention. However, the following embodiments are merely illustrative and the invention is not limited thereto.

[0165] [Preparation Example]

[0166] Preparation Example A: Preparation of Polymer Antibacterial Monomer 1-1

[0167]

[0168] Acetonitrile (30 ml), 2-(dimethylamino)ethyl methacrylate (0.05 mol), hexane (0.05 mol), and p-methoxyphenol (4 mg) were placed in a 250 ml flask. The reaction for preparing the quaternary ammonium salt by substitution of the amino group with an alkyl group was then carried out with stirring at 45 °C for 24 hours using a magnetic rod. After 24 hours, the completed solution was added to a diethyl ether solution (200 ml) for extraction. The reaction product was then filtered using a vacuum filter to completely remove the remaining diethyl ether to prepare the polymeric antimicrobial monomer 1-1 (15 g, yield: 75% or greater).

[0169] MS[M+H] + =322

[0170] 1 H NMR (500MHz, DMSO-d6, δ [ppm]): 6.07, 5.76 (R2, R3), 1.90 (R1), 4.51, 3.70, 3.69 (L), 3.09 (R4, R6), 1.26, 0.87 (R5)

[0171] Preparation Example B: Preparation of Polymer Antibacterial Monomers 1-2

[0172]

[0173] Polymer antimicrobial monomers 1-2 (15 g, yield: 75% or greater) were prepared in the same manner as in Preparation Example A, except that bromooctane was used instead of bromohexane in Preparation Example A.

[0174] MS[M+H] + =350

[0175] 1 H NMR (500MHz, DMSO-d6, δ [ppm]): 6.07, 5.76 (R2, R3), 1.90 (R1), 4.51, 3.70, 3.69 (L), 3.09 (R4, R6), 1.26, 0.87 (R5)]

[0176] Preparation Example C: Preparation of Polymer Antibacterial Monomers 1-3

[0177]

[0178] Polymer antimicrobial monomers 1-3 (15 g, yield: 75% or greater) were prepared in the same manner as in Preparation Example A, except that bromodecane was used instead of bromohexane in Preparation Example A.

[0179] MS[M+H] + =378

[0180] 1 H NMR (500MHz, DMSO-d6, δ [ppm]): 6.07, 5.76 (R2, R3), 1.90 (R1), 4.51, 3.70, 3.69 (L), 3.09 (R4, R6), 1.26, 0.87 (R5)

[0181] Preparation Example D: Preparation of Polymer Antibacterial Monomers 1-4

[0182]

[0183] Polymer antimicrobial monomers 1-4 (15 g, yield: 75% or greater) were prepared in the same manner as in Preparation Example A, except that bromododecane was used instead of bromohexane in Preparation Example A.

[0184] MS[M+H] + =406

[0185] 1 H NMR (500MHz, DMSO-d6, δ [ppm]): 6.07, 5.76 (R2, R3), 1.90 (R1), 4.51, 3.70, 3.69 (L), 3.09 (R4, R6), 1.26, 0.87 (R5)

[0186] [Examples and Comparative Examples]

[0187] Example 1

[0188] Acrylic acid (100g), polyethylene glycol diacrylate (Mn=575, 0.23g) as an internal crosslinking agent, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (0.008g) as a photoinitiator, sodium persulfate (SPS, 0.12g) as a thermal initiator, 98% sodium hydroxide solution (39.7g), and the polymer antibacterial monomer 1-1 (1g) prepared in Preparation Example A were placed in a 3L glass container equipped with a stirrer, a nitrogen injector, and a thermometer, and an aqueous solution of water-soluble unsaturated monomer was prepared by continuously adding nitrogen gas to the container.

[0189] An aqueous solution of the water-soluble unsaturated monomer was added to a stainless steel container with a width of 250 mm, a length of 250 mm, and a height of 30 mm, and then irradiated with ultraviolet light in a UV chamber at 80°C (irradiation dose: 10 mV / cm). 2 60 seconds and aged for 2 minutes to obtain an aqueous gel polymer.

[0190] The obtained aqueous gel polymer was pulverized to a size of 3 mm x 3 mm. The resulting gel-type resin was then spread on a stainless steel wire mesh with a pore size of 600 μm to a thickness of approximately 30 mm and dried in a hot air oven at 120°C for 10 hours. The resulting dried polymer was then pulverized using a pulverizer and sieved using an ASTM standard sieve to obtain a base polymer with a particle size of 300 μm to 600 μm, which was identified as a superabsorbent polymer.

[0191] Example 2

[0192] The superabsorbent polymer was prepared in the same manner as in Example 1, except that in Example 1, the polymer antimicrobial monomer 1-2 prepared in Preparation Example B was used instead of the polymer antimicrobial monomer 1-1 prepared in Preparation Example A.

[0193] Example 3-1

[0194] The superabsorbent polymer was prepared in the same manner as in Example 1, except that in Example 1, the polymer antimicrobial monomer 1-3 prepared in Preparation Example C was used instead of the polymer antimicrobial monomer 1-1 prepared in Preparation Example A.

[0195] Example 3-2

[0196] The superabsorbent polymer was prepared in the same manner as in Example 1, except that 0.1 g of the antimicrobial monomer 1-3 prepared in Preparation Example C was used in Example 3-1.

[0197] Example 3-3

[0198] The superabsorbent polymer was prepared in the same manner as in Example 1, except that 10g of the polymer antimicrobial monomer 1-3 prepared in Preparation Example C was used in Example 3-1.

[0199] Examples 3-4

[0200] The superabsorbent polymer was prepared in the same manner as in Example 1, except that 20g of the polymer antimicrobial monomer 1-3 prepared in Preparation Example C was used in Example 3-1.

[0201] Example 4-1

[0202] The superabsorbent polymer was prepared in the same manner as in Example 1, except that in Example 1, the polymer antimicrobial monomer 1-4 prepared in Preparation Example D was used instead of the polymer antimicrobial monomer 1-1 prepared in Preparation Example A.

[0203] Example 4-2

[0204] The superabsorbent polymer was prepared in the same manner as in Example 1, except that 0.5 g of the polymer antimicrobial monomer 1-4 prepared in Preparation Example D was used in Example 4-1.

[0205] Example 4-3

[0206] The superabsorbent polymer was prepared in the same manner as in Example 1, except that 2g of the polymer antimicrobial monomer 1-4 prepared in Preparation Example D was used in Example 4-1.

[0207] Example 4-4

[0208] The superabsorbent polymer was prepared in the same manner as in Example 1, except that 10g of the polymer antimicrobial monomer 1-4 prepared in Preparation Example D was used in Example 4-1.

[0209] Comparative Example 1

[0210] The superabsorbent polymer was prepared in the same manner as in Example 1, except that antimicrobial monomers were not used in Example 1.

[0211] Comparative Example 2

[0212] The superabsorbent polymer was prepared in the same manner as in Example 1, except that 0.01 g of the polymer antimicrobial monomer 1-3 prepared in Preparation Example C was used in Example 3-1.

[0213] Comparative Example 3

[0214] The superabsorbent polymer was prepared in the same manner as in Example 1, except that 25g of the polymer antimicrobial monomer 1-3 prepared in Preparation Example C was used in Example 3-1.

[0215] Comparative Example 4

[0216] 9.9 g of the superabsorbent polymer prepared in Comparative Example 1 and 0.1 g of the antimicrobial monomers 1-4 prepared in Preparation Example D were simply mixed (in the same proportion as the antimicrobial monomers used in the superabsorbent polymer prepared in Examples 4-1).

[0217] [Experimental Example 1]

[0218] The physical properties of the superabsorbent polymers prepared in the Examples and Comparative Examples were evaluated using the following methods, and the results are shown in Tables 1 and 2 below. Unless otherwise indicated, all the following physical properties were evaluated at constant temperature and constant humidity (23 ± 1 °C, 50 ± 10% relative humidity), and the salt solution or brine refers to an aqueous solution of 0.9% by weight of sodium chloride (NaCl).

[0219] (1) Centrifugation Retention Capacity (CRC)

[0220] The centrifugal retention capacity of the superabsorbent polymers of the Examples and Comparative Examples was measured by the absorption rate under no-load according to the European Disposable Products and Nonwovens Association (EDANA) standard WSP 241.3.

[0221] In detail, W0(g) (approximately 0.2g) of the superabsorbent polymer was uniformly placed in a bag made of nonwoven fabric and sealed. The bag was then immersed in a saline solution (0.9 wt% sodium chloride aqueous solution) at room temperature. After 30 minutes, the bag was drained for 3 minutes using a centrifuge at 250G, and the weight W2(g) of the bag was measured. The same procedure was then performed without the polymer, and the weight W1(g) was measured at this point. Using each obtained weight, CRC (g / g) was calculated according to the following equation. The results are shown in Table 1 below.

[0222] [Mathematical Equation 1]

[0223] CRC(g / g)={[W2(g)-W1(g)] / W0(g)}-1

[0224] In mathematical equation 1,

[0225] W0(g) represents the initial weight (g) of the superabsorbent polymer.

[0226] W1(g) represents the weight of the bag without the superabsorbent polymer, which is obtained by immersing the bag in physiological saline for 30 minutes to absorb the saline solution, followed by dehydration at 250g for 3 minutes using a centrifuge.

[0227] W2(g) represents the weight of the bag with the superabsorbent polymer, which absorbs physiological saline by immersing the bag in physiological saline at room temperature for 30 minutes and then dehydrating it at 250G for 3 minutes using a centrifuge.

[0228] (2) Evaluation of the antibacterial properties of Proteus mirabilis

[0229] Two g of each of the superabsorbent polymers prepared in the examples and comparative examples were placed in a 250 mL cell culture flask, and 50 mL of artificial urine inoculated with the test bacteria (Proteus mirabilis (ATCC 7002)) at a concentration of 3000 ± 300 CFU / mL was injected into the flask. Subsequently, to allow the superabsorbent polymers to fully absorb the artificial urine solution, they were mixed for approximately 1 minute. When the polymers had fully absorbed the solution, they exhibited a gel form, and were incubated in an incubator (JEIO TECH) at 35°C for 12 hours. 150 mL of 0.9 wt% NaCl solution was added to the incubated sample, followed by shaking for approximately 1 minute. This dilution was spread onto an agar plate. Serial dilutions were then performed for colony counting, using 0.9 wt% NaCl solution in this step. Antimicrobial performance was determined by calculating the initial bacterial concentration (Co, CFU / mL) based on the dilution concentration, and then calculating the antimicrobial rate (%) of Proteus mirabilis (ATCC 7002) according to the following mathematical equation 1. The results are shown in Table 1 below.

[0230] [Mathematical Equation 1]

[0231]

[0232] Where C 样品 This indicates the CFU of bacteria in a superabsorbent polymer containing antimicrobial material after incubation, and C... 参照 The CFU of bacteria after incubation in the superabsorbent polymer of Comparative Example 1, which does not contain antimicrobial materials.

[0233] (3) Assessment of leakage of antimicrobial monomers

[0234] To check for leakage of antimicrobial monomers from the superabsorbent polymer prepared in the examples, the residual amount of antimicrobial monomers was measured. Specifically, 0.1 g of the prepared superabsorbent polymer was shaken with 20 ml of 0.9 wt% saline solution for 1 hour, then the liquid extract was filtered, and the amount of leaked antimicrobial monomers was checked using UPLC / QDa. The results are shown in Table 1 below.

[0235] [Table 1]

[0236]

[0237]

[0238] Referring to Table 1, it was determined that, unlike the superabsorbent polymer of the comparative example, the superabsorbent polymer of the examples exhibited excellent antibacterial properties against Proteus mirabilis (a Gram-negative bacterium) while meeting a 30-minute centrifugation retention capacity (CRC) of 29 g / g to 50 g / g against physiological saline (0.9 wt% sodium chloride aqueous solution) as measured according to EDANA standard WSP 241.3.

[0239] Furthermore, unlike the superabsorbent polymer of Comparative Example 4, in which the antimicrobial monomer and the superabsorbent polymer were simply mixed, the superabsorbent polymer of the Examples showed no detectable residual antimicrobial monomer. Therefore, it was determined that the superabsorbent polymer of the Examples can consistently exhibit excellent antimicrobial properties without leakage of antimicrobial agent over time.

[0240] (4) Evaluation of antibacterial properties against Escherichia coli

[0241] To examine the antibacterial properties of the superabsorbent polymers prepared in the examples and comparative examples against *E. coli*, their antibacterial rate (%) against *E. coli* (ATCC 25922) was calculated in the same manner as in the evaluation of antibacterial properties against *Proteus mirabilis*, except that a 10-1 ratio was used. 5 Artificial urine inoculated with Escherichia coli (ATCC 25922) at a concentration of ±1000 CFU / ml was used instead of artificial urine inoculated with Proteus mirabilis (ATCC 7002) at a concentration of 3000 ± 300 CFU / ml. The results are shown in Table 2 below.

[0242] (5) Evaluation of antimicrobial properties against Enterococcus faecalis

[0243] To examine the antimicrobial properties of the superabsorbent polymers prepared in the Examples and Comparative Examples against Enterococcus faecalis, the antimicrobial rate (%) against Enterococcus faecalis (ATCC29212) was calculated in the same manner as in evaluating the antimicrobial properties against Proteus mirabilis, except that artificial urine inoculated with Enterococcus faecalis (ATCC29212) at 3000±300 CFU / ml was used instead of artificial urine inoculated with Proteus mirabilis (ATCC7002) at 3000±300 CFU / ml. The results are shown in Table 2 below.

[0244] [Table 2]

[0245]

[0246] Referring to Table 2, it was determined that the superabsorbent polymers of the embodiments also exhibited excellent antibacterial properties against Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Enterococcus faecalis).

[0247] Therefore, it was determined that superabsorbent polymers comprising cross-linked polymers prepared by using antimicrobial monomers with a specific structure having a quaternary ammonium salt moiety can exhibit water retention capacity higher than a predetermined level, while also exhibiting antimicrobial properties against both Gram-positive and Gram-negative bacteria.

[0248] [Experimental Example 2]

[0249] The rheological properties of the superabsorbent polymer according to the present invention were analyzed by the following methods.

[0250] 1) Test Sample

[0251] The following six types of samples are used:

[0252] #1: The superabsorbent polymer prepared in Example 3-1 was used as sample #1.

[0253] #2: Using a high-speed mixer, 100g of the superabsorbent polymer prepared in Example 3-1 was mixed with a solution containing 3g of water, 3g of methanol and 0.2g of ethylene glycol diglycidyl ether, and reacted at 140°C for 40 minutes. The mixture was then cooled to room temperature to prepare the superabsorbent polymer, which was used as sample #2.

[0254] #3: Using a high-speed mixer, 100g of the superabsorbent polymer prepared in Example 3-1 was mixed with a solution containing 3g of water, 3g of methanol and 0.2g of 1,3-propanediol, and reacted at 140°C for 40 minutes. The mixture was then cooled to room temperature to prepare the superabsorbent polymer, which was used as sample #3.

[0255] #4: The superabsorbent polymer was prepared in the same manner as in Example 3-1. Then, 100g of the prepared superabsorbent polymer was mixed with a solution containing 3g of water, 3g of methanol and 0.2g of ethylene glycol diglycidyl ether using a high-speed mixer and reacted at 140°C for 40 minutes. The mixture was then cooled to room temperature to prepare the superabsorbent polymer, which was used as sample #4.

[0256] #5: Using a high-speed mixer, 100g of the superabsorbent polymer prepared in Comparative Example 1 was mixed with a solution containing 3g of water, 3g of methanol and 0.2g of ethylene glycol diglycidyl ether, and reacted at 140°C for 40 minutes. The mixture was then cooled to room temperature to prepare the superabsorbent polymer, which was used as sample #6.

[0257] #6: BASF's single odor control liquid (OC6600)

[0258] 2) Creep test

[0259] A force of 10 Pa was applied to the sample for 1 minute to measure the strain, and then the force was removed for 2 minutes to measure the recovery rate. The results are presented below. Figure 1 And in Table 3 below.

[0260] [Table 3]

[0261] #1 1.23 72 #2 0.40 78 #3 0.32 100 #4 0.43 84 #5 0.45 67 #6 0.52 67

[0262] like Figure 1 As shown in Table 3, the maximum strain after surface cross-linking (#2, #3, #4) is reduced compared to the maximum strain before surface cross-linking (#1), indicating that the maximum strain decreases due to the increased elasticity caused by the formation of the core-shell structure. Furthermore, all the superabsorbent polymers (#1, #2, #3, #4) according to the invention exhibit a recovery rate of 70% or greater, which is higher than the recovery rate of general superabsorbent polymers (#5, #6). This demonstrates that wearing comfort can be maintained for a long time and the structural possibility of damage to the superabsorbent polymer is low.

[0263] 3) Frequency sweep test and amplitude sweep test

[0264] The sample was subjected to frequency scanning tests, and specifically, the gel strength was measured as follows.

[0265] Immerse 1g of sample in 100g of physiological saline and allow it to swell for 1 hour. Afterward, remove unabsorbed solvent using a suction device for 4 minutes, and wipe off any remaining solvent on the surface by wiping it off once, spreading it evenly on filter paper.

[0266] A 2.5 g sample of swollen superabsorbent polymer was placed between a rheometer and two plates (25 mm in diameter with approximately 2 mm walls at the bottom to prevent sample leakage). The gap between the plates was adjusted to 1 mm. (If it is difficult to adjust the gap to 1 mm due to the sample's hardness, a force of approximately 3 N is applied to the plates, and the gap is controlled so that the swollen superabsorbent polymer sample is in complete contact with the plates.) The superabsorbent polymer sample was then allowed to stabilize between the plates for approximately 5 minutes. The strain was then determined within a linear viscoelastic state region with constant storage modulus (G') and loss modulus (G”) as the strain was increased using the rheometer at a frequency of 10 radians / second. Typically, 0.1% strain exists in the linear viscoelastic state region in the swollen superabsorbent polymer sample. The viscoelasticity (G', G”) of the superabsorbent polymer swollen for 60 seconds under strain in the linear state region was measured at a constant frequency of 10 radians / second. The average value of G' was determined as the gel strength.

[0267] The results are shown in Figure 2 and Figure 3 And in Table 4.

[0268] [Table 4]

[0269]

[0270]

[0271] like Figure 2 As shown in Table 4, the gel strength after surface crosslinking (#2, #3, #4) increases compared to the gel strength before surface crosslinking (#1), indicating the formation of a core-shell structure. Furthermore, the superabsorbent polymers (#1, #2, #3, #4) according to the present invention exhibit higher or similar levels of gel strength compared to general superabsorbent polymers (#5, #6), indicating that the mechanical properties are similarly maintained or improved.

[0272] like Figure 3 As shown, unlike before surface crosslinking (#1), strain overshoot behavior was observed in the loss modulus after surface crosslinking (#2, #3, #4), indicating the formation of a core-shell structure due to surface crosslinking.

[0273] 4) Penetration rate

[0274] As described in the literature (Buchholz, FL and Graham, AT, "Modern Superabsorbent Polymer Technology," John Wiley & Sons (1998), p. 161), permeability was measured using a 0.9% saline solution at a load of 0.3 psi.

[0275] More specifically, 0.2 g of particles with a size of 300 μm to 600 μm were taken from each sample and added to a cylinder (Φ20 mm) having a stopcock valve at one end, an upper limit mark, and a lower limit mark. The upper limit mark on the cylinder indicates the position where 40 ml (saline) solution is filled into the cylinder, and the lower limit mark on the cylinder indicates the position where 20 ml (saline) solution is filled into the cylinder.

[0276] Add 50 g of 0.9% saline (NaCl) solution to a cylinder with a stopcock valve in the closed position and let it stand for 30 minutes. Then, if necessary, add additional saline solution to the cylinder to bring the saline solution level to the upper limit mark on the cylinder. Next, apply a load of 0.3 psi to the cylinder containing the superabsorbent polymer that has absorbed the saline solution and let it stand for 1 minute. Afterward, open the stopcock valve at the bottom of the cylinder to measure the time taken for the 0.9% saline solution to travel from the upper limit mark to the lower limit mark on the cylinder. All measurements were performed at a temperature of 24 ± 1 °C and a relative humidity of 50 ± 10%.

[0277] The time (T) taken to measure the time it takes for a sample to pass from the upper limit mark to the lower limit mark. s Furthermore, in the absence of superabsorbent polymers, the time (T0) taken to pass from the upper limit mark to the lower limit mark was measured, and the permeability was calculated using Equation 1 below. The results are shown in Table 5.

[0278] [Equation 1]

[0279] Permeability (seconds) = T s -T0

[0280] [Table 5]

[0281] #2 83 #3 81 #4 84 #5 78

[0282] As shown in Table 5, the superabsorbent polymers according to the present invention have the permeability typically required for superabsorbent polymers.

Claims

1. A superabsorbent polymer comprising an acrylic acid-based monomer containing at least partially neutralized acidic groups, a polymeric antimicrobial monomer represented by any of the following chemical formulas 1-1 to 1-4, and an internal crosslinking agent, comprising a crosslinked polymer. The polymeric antimicrobial monomer is contained in the crosslinked polymer in an amount of 0.1 to 2 parts by weight relative to 100 parts by weight of the acrylic-based monomer, and The internal crosslinking agent is trimethylolpropane tri(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, butanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, hexanediol di(meth)acrylate, triethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, dipentaerythritol pentaacrylate, glycerol tri(meth)acrylate, or pentaerythritol tetraacrylate. ， In chemical formulas 1-1 to 1-4, a is 4, 5, or 6. b is 4, 5, or 6, and X is bromine.

2. The superabsorbent polymer of claim 1 further comprises a surface-modified layer on the crosslinked polymer, wherein the surface-modified layer is prepared by further crosslinking the crosslinked polymer via a surface crosslinking agent.

3. The superabsorbent polymer according to claim 1, wherein... The superabsorbent polymer has a 30-minute centrifugal retention capacity (CRC) of 38 g / g to 50 g / g in physiological saline (0.9 wt% sodium chloride aqueous solution), as measured according to EDANA standard WSP 241.

3.

4. The superabsorbent polymer according to claim 1, wherein... According to creep tests, the superabsorbent polymer exhibits a maximum strain of 0.30% to 1.50% and a recovery rate of 70% to 100%.

5. The superabsorbent polymer according to claim 1, wherein... The gel strength of the superabsorbent polymer is between 1500 Pa and 5000 Pa.

6. The superabsorbent polymer according to claim 1, wherein... The permeability of the superabsorbent polymer is 70 to 150 seconds.

7. The superabsorbent polymer according to claim 1, wherein... The superabsorbent polymer has a core-shell structure.

8. The superabsorbent polymer according to claim 1, wherein... The superabsorbent polymer exhibits antimicrobial properties against at least one of Gram-positive and Gram-negative bacteria.

9. The superabsorbent polymer according to claim 8, wherein... The superabsorbent polymer exhibits antibacterial properties against both Gram-positive and Gram-negative bacteria.

10. The superabsorbent polymer according to claim 8, wherein... The Gram-negative bacteria are Proteus Mirabilis or Escherichia coli, and the Gram-positive bacteria are Enterococcus faecalis.

11. A method for preparing the superabsorbent polymer according to claim 1, the method comprising the following steps: Aqueous gel polymers are formed by crosslinking an acrylic-based monomer containing at least partially neutralized acidic groups and a polymeric antimicrobial monomer represented by any of the following chemical formulas 1-1 to 1-4 in the presence of an internal crosslinking agent and a polymerization initiator; and A superabsorbent polymer comprising a crosslinked polymer is formed by drying, pulverizing, and size sorting the aqueous gel polymer. The polymeric antimicrobial monomer is used in an amount of 0.1 to 2 parts by weight relative to 100 parts by weight of the acrylic-based monomer. ， In chemical formulas 1-1 to 1-4, a is 4, 5, or 6. b is 4, 5, or 6, and X is bromine.

12. The method of claim 11, further comprising the step of crosslinking the surface of the superabsorbent polymer by heat treatment in the presence of a surface crosslinking agent.

13. The method of claim 11, wherein The prepared superabsorbent polymers exhibit antibacterial properties against at least one of Gram-positive and Gram-negative bacteria.

14. A composition comprising the superabsorbent polymer according to any one of claims 1 to 10.

15. An article comprising the superabsorbent polymer according to any one of claims 1 to 10.

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