Superabsorbent polymer composition and method for preparing same

Abstract

The present invention relates to a superabsorbent polymer composition and a method for preparing the same. In particular, the present invention provides a superabsorbent polymer composition having excellent deodorizing ability while minimizing degradation of physical properties of a superabsorbent polymer by controlling and mixing a combination of deodorizing materials, and a method for preparing the same.

Description

Technical Field

[0001] Cross-reference to related applications

[0002] This application is based on Korean Patent Application No. 10-2023-0073035, filed on June 7, 2023, and Korean Patent Application No. 10-2024-0073975, filed on June 5, 2024, and claims the priority thereof, the entire disclosures of which are incorporated herein by reference in their entirety.

[0003] The present invention relates to a superabsorbent polymer composition and a method for preparing the same. Specifically, the present invention relates to a superabsorbent polymer composition having a deodorizing ability and a method for preparing the same. Background Art

[0004] A superabsorbent polymer (SAP) is a synthetic polymer material capable of absorbing 500 to 1000 times its own weight of moisture. Various manufacturers have named it different names, such as SAM (superabsorbent material), AGM (absorbent gel material), etc. Since such superabsorbent polymers began to be practically applied to sanitary products, and they are now widely used not only in sanitary products such as disposable diapers for children, etc., but also in water-retaining soil products for horticulture, water-stopping materials for civil engineering and construction, sheets for raising seedlings, preservatives for the food distribution field, materials for pastes, etc.

[0005] In most cases, these superabsorbent polymers have been widely used in fields such as diapers or sanitary napkins, etc. as sanitary materials. Inside the sanitary materials, the superabsorbent polymers are usually distributed throughout the pulp. However, recently, efforts have been made to provide sanitary materials, such as diapers with a thinner thickness, etc., and as part of this, diapers with a reduced pulp content and diapers without pulp, i.e., so-called pulp-free diapers, are being actively developed.

[0006] As described above, such sanitary materials with a reduced pulp content or without pulp contain a relatively high ratio of superabsorbent polymers, and the superabsorbent polymer particles are inevitably included in the sanitary materials as multiple layers. In order to allow the entire superabsorbent polymer particles included as multiple layers to more effectively absorb liquids (such as urine, etc.), it is necessary for the superabsorbent polymer to basically exhibit high absorption performance and a high absorption rate. In addition, the superabsorbent polymer should not release the absorbed liquid even under external pressure, and liquid permeability is required to maintain its original shape well even in a swollen state by absorbing liquids.

[0007] Therefore, in order to improve the basic absorbency and water retention ability of the superabsorbent polymer, many studies, such as surface crosslinking, etc., are being conducted.

[0008] Meanwhile, superabsorbent polymers can be used in hygiene materials, and in this case, there may be a problem of reduced usability due to the unpleasant odor of the absorbed liquid (such as human and pet excrement). In particular, it is necessary to suppress the odor initially contained in the absorbed liquid and the odor generated during the use of the hygiene material containing the superabsorbent polymer.

[0009] Traditionally, superabsorbent polymers are mixed with deodorizing materials. However, mixing with an excessive amount of deodorizing material to effectively suppress the odor reduces the absorbency, or there is a problem that the desired level of deodorizing ability cannot be achieved only for antibacterial purposes.

[0010] Therefore, the demand for unpleasant odor suppression and for absorbency and water retention ability, which are the basic physical properties of superabsorbent polymers, is increasing. Therefore, it is necessary to prepare a superabsorbent polymer having excellent deodorizing ability. Summary of the Invention

[0011] Technical problem

[0012] The present invention provides a superabsorbent polymer composition having deodorizing ability and a method for preparing the same.

[0013] More specifically, a superabsorbent polymer composition having excellent deodorizing ability and a method for preparing the same are provided, in which the deterioration of the physical properties of the superabsorbent polymer caused by mixing with a deodorizing material is minimized by controlling the combination of deodorizing materials.

[0014] Technical solution

[0015] To achieve the above object, the following superabsorbent polymer composition is provided:

[0016] The superabsorbent polymer composition comprises:

[0017] A superabsorbent polymer, which comprises: a base polymer and a surface crosslinked layer, the base polymer being a crosslinked polymer obtained by crosslinking polymerization of an acrylic monomer having at least partially neutralized acidic groups and an internal crosslinking agent, the surface crosslinked layer being formed on the surface of the base polymer, wherein the crosslinked polymer is additionally crosslinked via a surface crosslinking agent; tannic acid; an iodine compound; and a chelating agent.

[0018] A method for preparing a superabsorbent polymer composition is also provided:

[0019] The method comprises the following steps:

[0020] Forming a hydrogel polymer by crosslinking polymerization of an acrylic monomer having at least partially neutralized acidic groups in the presence of an internal crosslinking agent and a polymerization initiator (step 1);

[0021] Prepare a base polymer containing a crosslinked polymer by coarsely pulverizing, drying, and pulverizing the aqueous gel polymer (Step 2);

[0022] Prepare a mixture by mixing the base polymer with a surface crosslinking agent (Step 3); and

[0023] Prepare a superabsorbent polymer by heat-treating the mixture, wherein a surface crosslinked layer is formed on the surface of the base polymer (Step 4);

[0024] Wherein tannic acid and an iodine compound are mixed with the superabsorbent polymer of Step 4 on which a surface crosslinked layer is formed, and a chelating agent is mixed in the coarsely pulverizing step of Step 2 or with the superabsorbent polymer of Step 4 on which a surface crosslinked layer is formed.

[0025] Advantageous effects

[0026] As described above, the present invention is characterized in that a superabsorbent polymer composition having excellent deodorizing ability and a method for preparing the same are provided by applying a combined deodorizing material to the superabsorbent polymer.

[0027] Specifically, the present invention is characterized in that a superabsorbent polymer composition and a method for preparing the same are provided, and the superabsorbent polymer composition can remove both the unpleasant odor generated by urine initially excreted by the human body and the unpleasant odor generated by bacteria on the skin during the use of sanitary products or when the used sanitary products are unattended. Detailed Description

[0028] The terms used in this specification are only for explaining exemplary embodiments and are not intended to limit the present invention. Singular expressions may include plural expressions unless otherwise expressed in the context. It must be understood that the terms "comprising", "equipped with" or "having" in this specification are only used to specify the presence of the features, steps, components or combinations thereof adopted, and do not exclude the pre-existence or possible addition of one or more different features, steps, components or combinations thereof.

[0029] The present invention can be variously modified and has various forms, and specific exemplary embodiments are illustrated and explained in detail in the following description. However, it is not intended to limit the present invention to the specific exemplary embodiments, and it must be understood that the present invention includes every modification, equivalent or substitution included within the spirit and technical scope of the present invention.

[0030] Hereinafter, a superabsorbent polymer composition and a method for preparing the same will be described in more detail according to specific embodiments of the present invention.

[0031] Prior to this, the terms used in this specification are only used to refer to specific exemplary embodiments and are not intended to limit the present invention. In addition, unless the context clearly indicates otherwise, the singular forms used herein also include the plural forms.

[0032] For reference, the "superabsorbent polymer" in this specification refers to the superabsorbent polymer itself, or depending on the context, it can be used to cover those made suitable for production through additional processes such as surface crosslinking, fine powder reassembly, drying, pulverization, classification, etc.

[0033] In addition, the "base polymer" or "base polymer powder" in this specification refers to particles or powder made by drying and pulverizing a polymer of an acrylic monomer, and it refers to a polymer that does not undergo surface modification or surface crosslinking steps as explained later.

[0034] (Superabsorbent Polymer Composition)

[0035] According to an embodiment of the present invention, a superabsorbent polymer composition is provided.

[0036] The superabsorbent polymer composition includes: a superabsorbent polymer, which includes a base polymer and a surface crosslinked layer, the base polymer includes a crosslinked polymer, in which an acrylic monomer having at least partially neutralized acidic groups and an internal crosslinking agent are crosslinked and polymerized, the surface crosslinked layer is formed on the surface of the base polymer, in which the crosslinked polymer is additionally crosslinked via a surface crosslinking agent; tannic acid; an iodine compound; and a chelating agent.

[0037] The acrylic monomer can be any monomer commonly used to prepare a superabsorbent polymer. Specifically, the acrylic monomer can be a compound represented by the following Chemical Formula 1:

[0038] [Chemical Formula 1]

[0039] R 1 -COOM 1

[0040] In Chemical Formula 1,

[0041] R 1 is a C2-C5 alkyl group containing an unsaturated bond, and

[0042] M 1 is a hydrogen atom, a monovalent or divalent metal, an ammonium group, or an organic amine salt.

[0043] Preferably, the acrylic monomer can include one or more selected from the group consisting of acrylic acid, methacrylic acid, and their monovalent metal salts, their divalent metal salts, their ammonium salts, and their organic amine salts.

[0044] The acrylic monomer has an acidic group, and at least a part of the acidic group can be neutralized. Preferably, those prepared by partially neutralizing the monomer with a basic substance such as sodium hydroxide, potassium hydroxide, ammonium hydroxide, etc. can be used.

[0045] In this regard, the degree of neutralization of the monomer can be 40 mol% to 95 mol%, or 40 mol% to 80 mol%, or 45 mol% to 75 mol%. The range of the degree of neutralization can vary according to the final physical properties. However, when the degree of neutralization is too high, the neutralized monomer precipitates, so polymerization may not easily occur. On the contrary, when the degree of neutralization is too low, the absorbency of the polymer is significantly reduced, and in addition, the polymer may exhibit properties that are difficult to handle, such as elastic rubber.

[0046] Meanwhile, in order to improve the physical properties of the polymer by polymerization of the acrylic monomer, it is carried out in the presence of a crosslinking agent (“internal crosslinking agent”). The crosslinking agent is used for internal crosslinking of the hydrogel polymer and can be used separately from the “surface crosslinking agent” described later.

[0047] As the internal crosslinking agent, any compound can be used as long as it can introduce crosslinking bonds during the polymerization of the acrylic monomer. As non-limiting examples of the internal crosslinking agent, polyfunctional crosslinking agents such as N,N'-methylenebisacrylamide, trimethylolpropane tri(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polypropylene glycol di(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, triallylamine, allyl (meth)acrylate, ethylene glycol diglycidyl ether, propylene glycol, ethylene carbonate can be used alone or in combination of two or more thereof.

[0048] Such an internal crosslinking agent can be added at a concentration of 0.001 wt% to 1 wt%, or 0.01 wt% to 0.8 wt%, or 0.1 wt% to 0.7 wt% relative to the monomer composition. In other words, when the concentration of the internal crosslinking agent is too low, the absorption rate of the polymer may decrease and the gel strength may become weak, which is not preferred. On the contrary, when the concentration of the internal crosslinking agent is too high, the absorption capacity of the polymer may decrease, which is not preferred as an absorbent.

[0049] In addition, as needed, the base polymer may further include additives such as thickeners, plasticizers, storage stabilizers, antioxidants, and the like.

[0050] The surface crosslinked layer is obtained by additionally crosslinking the crosslinked polymer via a surface crosslinking agent. In this regard, the surface crosslinking agent is not particularly limited as long as it is a surface crosslinking agent commonly used for surface crosslinking of superabsorbent polymers and is a compound capable of reacting with the functional groups of the polymer.

[0051] Preferably, in order to improve the properties of the superabsorbent polymer to be prepared, one or more selected from the group consisting of the following may be used as the surface crosslinking agent: polyhydric alcohols; epoxy compounds; polyamine compounds; halogenated epoxy compounds; condensation products of halogenated epoxy compounds; oxazoline compounds; mono-, di- or polyoxazolidinone compounds; cyclic urea compounds; polyvalent metal salts; and alkylene carbonate compounds.

[0052] Specifically, as examples of polyhydric alcohol compounds, one or more selected from the group consisting of the following may be used: mono-, di-, tri-, tetra- or polyethylene glycol, monopropylene glycol, 1,3-propanediol, dipropylene glycol, 2,3,4-trimethyl-1,3-pentanediol, polypropylene glycol, glycerol, polyglycerol, 2-butene-1,4-diol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 1,2-cyclohexanedimethanol.

[0053] In addition, ethylene glycol diglycidyl ether and glycidol can be used as epoxy compounds, and one or more selected from the group consisting of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, polyethyleneimine, and polyamide polyamine can be used as polyamine compounds.

[0054] In addition, as halogenated epoxy compounds, epichlorohydrin, epibromohydrin, and α-methyl epichlorohydrin can be used. Meanwhile, as mono-, di- or polyoxazolidinone compounds, 2-oxazolidinone can be used, for example.

[0055] In addition, as alkylene carbonate compounds, ethylene carbonate and the like can be used. These compounds can be used alone or in combination. Meanwhile, in order to improve the efficiency of the surface crosslinking process, it is preferred to include one or more C2 to C10 polyhydric alcohol compounds in the surface crosslinking agent.

[0056] Specifically, the content of the surface crosslinking agent to be added can be appropriately selected according to the type of the surface crosslinking agent or the reaction conditions. However, generally, the amount used can be about 0.001 parts by weight to about 5 parts by weight, preferably about 0.01 parts by weight to about 3 parts by weight, more preferably about 0.05 parts by weight to about 2 parts by weight, based on 100 parts by weight of the polymer.

[0057] When the content of the surface crosslinking agent is too small, the surface crosslinking reaction may hardly occur, and when the content relative to 100 parts by weight of the polymer exceeds 5 parts by weight, deterioration of the absorption capacity and physical properties may occur due to the progress of the excessive surface crosslinking reaction.

[0058] Meanwhile, the surface crosslinking agent may also include an inorganic material. As such an inorganic material, one or more inorganic materials selected from the group consisting of silica, clay, alumina, silica-alumina composite, titanium dioxide, zinc oxide, and aluminum sulfate can be used. The inorganic material can be used in the form of a powder or a liquid, particularly in the form of alumina powder, silica-alumina powder, titanium dioxide powder, or nano-silica solution. In addition, the amount of the inorganic material can be about 0.001 parts by weight to about 1 part by weight relative to 100 parts by weight of the base polymer.

[0059] The superabsorbent polymer composition according to an embodiment of the present invention may include tannic acid, an iodine compound, and a chelating agent as deodorizing materials. When the superabsorbent polymer composition containing tannic acid, an iodine compound, and a chelating agent is applied to a sanitary product, it can have the effect of removing the unpleasant odor of the liquid initially absorbed by the sanitary product, as well as the effect of removing the unpleasant odor that may be additionally generated due to bacterial growth during use.

[0060] Tannic acid is a polyphenol found in fruit peels, vegetables, cocoa, nuts, etc. Tannic acid has a hydroxyl group (-OH) in the molecule, and this hydroxyl group forms a hydrogen bond with the oxygen atom or nitrogen (N) atom of the compound that produces the unpleasant odor. Therefore, tannic acid can capture odor substances, thereby reducing the unpleasant odor.

[0061] The iodine compound can be an iodine solution ((I2) or a metal iodide salt. The iodine solution is in the form of I2 dissolved in water, and the metal iodide salt can be added during the preparation process in the form of one or more selected from the group consisting of CuI, NaI, and I2 dissolved together in water or in the form of a powder obtained by drying the aqueous solution. The iodine compound can be added to the superabsorbent polymer like tannic acid or a chelating agent to impart deodorizing properties. The iodine compound removes the unpleasant odor by oxidizing the odor substances and acts on most of the odor substances, thereby showing an overall effect.

[0062] The superabsorbent polymer composition according to an embodiment of the present invention may include a chelating agent. Bacterial proliferation occurs due to the encounter between bacteria such as those from the skin and the absorbed liquid. The sanitary product containing the superabsorbent polymer composition may produce additional unpleasant odors, and the chelating agent can inhibit the growth of these bacteria.

[0063] Chelating agents may include glycine salt chelating agents. Specifically, glycine salt chelating agents may include one or more selected from the group consisting of ethylenediaminetetraacetic acid (EDTA), L-glutamic acid diacetic acid (GLDA), methylglycine diacetic acid (MGDA), hydroxyethyl ethylenediamine triacetic acid (HEDTA), ethanol diglycine (ethanolamine diacetic acid, EDG), diethylenetriaminepentaacetic acid (DTPA), and their salts. More specifically, the chelating agent may be ethylenediaminetetraacetic acid (EDTA) or L-glutamic acid diacetic acid (GLDA).

[0064] Relative to 100 parts by weight of the base polymer, based on the solid content, the content of tannic acid may be greater than 0.001 part by weight to 0.5 part by weight, particularly greater than 0.001 part by weight, 0.002 part by weight or more, 0.003 part by weight or more, 0.005 part by weight or more, 0.01 part by weight or more, 0.015 part by weight or more, or 0.02 part by weight or more, and 0.5 part by weight or less, 0.3 part by weight or less, 0.1 part by weight or less, 0.07 part by weight or less, 0.05 part by weight or less, 0.04 part by weight or less, or 0.03 part by weight or less.

[0065] Only when the tannic acid meets the above content range can the maximum deodorizing ability be ensured while minimizing the deterioration of the physical properties of the superabsorbent polymer.

[0066] Relative to 100 parts by weight of the base polymer, the content of the iodine compound may be 0.01 part by weight to 1.0 part by weight, particularly 0.01 part by weight or more, 0.03 part by weight or more, 0.05 part by weight or more, 0.07 part by weight or more, or 0.1 part by weight or more, and 1 part by weight or less, 0.8 part by weight or less, 0.5 part by weight or less, or 0.3 part by weight or less.

[0067] Only when the iodine compound meets the above content range can the maximum deodorizing ability be ensured while minimizing the deterioration of the physical properties of the superabsorbent polymer.

[0068] Relative to 100 parts by weight of the base polymer, based on the solid content, the content of the chelating agent may be 0.05 part by weight to 4.0 parts by weight. Specifically, relative to 100 parts by weight of the base polymer, based on the solid content, the content of the chelating agent may be 0.05 part by weight or more, 0.1 part by weight or more, 0.3 part by weight or more, 0.5 part by weight or more, 0.7 part by weight or more, or 1.0 part by weight or more, and 4.0 parts by weight or less, 3.0 parts by weight or less, 2.0 parts by weight or less, 1.5 parts by weight or less, or 1.3 parts by weight or less.

[0069] In order to achieve deodorizing properties by suppressing bacterial growth to a level desired to be achieved in the present invention, minimizing deterioration of physical properties, and maintaining the inherent absorption properties of the superabsorbent polymer, the chelating agent is preferably included within the above content range.

[0070] In addition to tannic acid, iodine compounds, and chelating agents, the superabsorbent polymer composition may further contain additional additives.

[0071] The additional additives may further include one or more additives selected from the group consisting of organic acids, glycerin, and zinc chloride.

[0072] The organic acid may be one or more selected from the group consisting of citric acid, glycine, acetic acid, formic acid, fumaric acid, lactic acid, and propionic acid. In particular, the organic acid may be citric acid or glycine.

[0073] Like tannic acid, the organic acid can exhibit a deodorizing effect in the superabsorbent polymer. In addition, the organic acid has the effect of neutralizing ammonia dissolved in urine. In particular, glycine can capture malodorous substances by chemically reacting with them. Malodorous substances generally have a small molecular weight, and when they react with glycine, the malodor is reduced or eliminated, so the malodor can be effectively removed. In particular, glycine can effectively reduce the malodor of aldehyde and ketone compounds.

[0074] Glycerin generally helps dissolve various deodorizing materials and exerts deodorizing ability.

[0075] Zinc chloride acts as an antibacterial agent and preservative that inhibits bacterial metabolism and generally has antibacterial properties.

[0076] Tannic acid and iodine compounds can be included separately from the superabsorbent polymer. As described in the preparation method below, after forming a surface crosslinked layer on the surface of the base polymer, tannic acid and iodine compounds are mixed into the superabsorbent polymer. Therefore, tannic acid and iodine compounds can mainly exist outside the superabsorbent polymer particles.

[0077] The chelating agent can be included within the base polymer or included separately from the superabsorbent polymer. As described in the preparation method below, the chelating agent is mixed in the coarse grinding step of step 2, or mixed with the superabsorbent polymer after forming a surface crosslinked layer on the surface of the base polymer. In particular, when the chelating agent is mixed in the coarse grinding step of step 2, the chelating agent can be impregnated into the base polymer and can exist in the base polymer.

[0078] (Method for preparing superabsorbent polymer composition)

[0079] According to an embodiment of the present invention, a method for preparing a superabsorbent polymer composition is provided.

[0080] A method for preparing a superabsorbent polymer composition includes the following steps:

[0081] Forming a hydrogel polymer by crosslinking and polymerizing an acrylic monomer having at least partially neutralized acidic groups in the presence of an internal crosslinking agent and a polymerization initiator (step 1); preparing a base polymer containing a crosslinked polymer by coarsely crushing, drying, and pulverizing the hydrogel polymer (step 2); preparing a mixture by mixing the base polymer with a surface crosslinking agent (step 3); and preparing a superabsorbent polymer by heat-treating the mixture, wherein a surface crosslinked layer is formed on the surface of the base polymer (step 4);

[0082] Wherein tannic acid and an iodine compound are mixed with the superabsorbent polymer of step 4 in which a surface crosslinked layer is formed, and a chelating agent is mixed in the coarsely crushing step of step 2 or mixed with the superabsorbent polymer of step 4 in which a surface crosslinked layer is formed.

[0083] The method for preparing a superabsorbent polymer mainly includes: the step of preparing a hydrogel polymer by polymerizing an acrylic monomer and the step of pulverizing it. In addition, in order to improve various physical properties of the superabsorbent polymer, a method of surface crosslinking the prepared superabsorbent polymer is used.

[0084] The present invention aims to provide a superabsorbent polymer composition having deodorizing ability by mixing tannic acid, an iodine compound, and a chelating agent with a surface crosslinked superabsorbent polymer.

[0085] Hereinafter, each step of the present invention will be described in detail.

[0086] (Step 1)

[0087] Step 1 is the step of preparing a hydrogel polymer, and specifically, it is the step of forming a hydrogel polymer by crosslinking and polymerizing a monomer composition containing an acrylic monomer having at least partially neutralized acidic groups.

[0088] The acrylic monomer can be any monomer commonly used for preparing a superabsorbent polymer. Specifically, the acrylic monomer can be a compound represented by the following Chemical Formula 1:

[0089] [Chemical Formula 1]

[0090] R 1 -COOM 1

[0091] In Chemical Formula 1,

[0092] R 1 is a C2-C5 alkyl group containing an unsaturated bond, and

[0093] M 1 is a hydrogen atom, a monovalent or divalent metal, an ammonium group or an organic amine salt.

[0094] Preferably, the acrylic monomer may include one or more selected from the group consisting of acrylic acid, methacrylic acid, and their monovalent metal salts, their divalent metal salts, their ammonium salts, and their organic amine salts.

[0095] The acrylic monomer has an acidic group, at least a part of which can be neutralized. Preferably, those prepared by partially neutralizing the monomer with a basic substance such as sodium hydroxide, potassium hydroxide, ammonium hydroxide, etc. can be used.

[0096] In this regard, the degree of neutralization of the monomer can be 40 mol% to 95 mol%, or 40 mol% to 80 mol%, or 45 mol% to 75 mol%. The range of the degree of neutralization can vary according to the final physical properties. However, when the degree of neutralization is too high, the neutralized monomer precipitates, and thus polymerization may not easily occur. On the contrary, when the degree of neutralization is too low, the absorbency of the polymer is significantly reduced, and in addition, the polymer may exhibit properties that are difficult to handle, such as an elastic rubber.

[0097] The monomer composition may include a polymerization initiator commonly used for preparing a superabsorbent polymer.

[0098] Depending on the polymerization method, a thermal polymerization initiator or a photoinitiator can be used as the polymerization initiator. However, even during photopolymerization, a certain amount of heat can be generated by UV radiation, etc., and a certain amount of heat is also generated along with the polymerization reaction, which is an exothermic reaction. Therefore, a thermal polymerization initiator can also be included.

[0099] Here, as the photoinitiator, for example, one or more compounds selected from the group consisting of benzoin ethers, dialkyl acetophenones, hydroxyalkyl ketones, phenyl glyoxylates, benzyl dimethyl ketals, acylphosphines, and α - amino ketones can be used. Among them, specific examples of acylphosphines can include commercially available lucirin TPO, that is, 2,4,6 - trimethyl - benzoyl - diphenylphosphine oxide. More photoinitiators are disclosed on page 115 of "UV Coatings: Basics, Recent Developments and New Application (Elsevier, 2007)" written by Reinhold Schwalm, which can be used as a reference.

[0100] As a thermal polymerization initiator, one or more compounds selected from the group consisting of persulfate initiators, azo initiators, hydrogen peroxide, and ascorbic acid can be used. Specifically, the persulfate initiator can be, for example, sodium persulfate (Na2S2O8), potassium persulfate (K2S2O8), ammonium persulfate ((NH4)2S2O8), etc. In addition, the azo initiator can be, for example, 2,2-azobis(2-amidinopropane) dihydrochloride, 2,2-azobis(N,N-dimethyl) isobutyramidine dihydrochloride, 2-(carbamoylazo) isobutyronitrile, 2,2-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride, or 4,4-azobis(4-cyanovaleric acid), etc. More different thermal polymerization initiators are disclosed on page 203 of "Principle of Polymerization (Wiley, 1981)" written by Odian, which can be used as a reference.

[0101] This polymerization initiator can be added at a concentration of 0.001 wt% to 1 wt% or 0.005 wt% to 0.1 wt% relative to the monomer composition. In other words, when the concentration of the polymerization initiator is too low, the polymerization rate may become slow, and a large amount of the monomers remaining in the final product may be extracted, which is not preferred. On the contrary, when the concentration of the polymerization initiator is too high, the polymer chains constituting the network become short, so the content of the water-soluble component increases, and the physical properties of the polymer may deteriorate, such as a decrease in absorbency under pressure, which is not preferred.

[0102] Meanwhile, the polymerization of the monomer composition is carried out in the presence of a crosslinking agent ("internal crosslinking agent") to improve the physical properties of the polymer by the polymerization of acrylic monomers. The crosslinking agent is used for the internal crosslinking of the hydrogel polymer and can be used separately from the "surface crosslinking agent" described later.

[0103] As an internal crosslinking agent, any compound can be used as long as it can introduce crosslinking bonds during the polymerization of acrylic monomers. As non-limiting examples of internal crosslinking agents, polyfunctional crosslinking agents such as N,N'-methylenebisacrylamide, trimethylolpropane tri(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, butanediol di(meth)acrylate, butenediol 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, triallylamine, allyl (meth)acrylate, ethylene glycol diglycidyl ether, propylene glycol or ethylene carbonate can be used alone or in combination of two or more thereof.

[0104] Such an internal crosslinking agent can be added at a concentration of 0.001 wt% to 1 wt%, or 0.01 wt% to 0.8 wt%, or 0.1 wt% to 0.7 wt% relative to the monomer composition. In other words, when the concentration of the internal crosslinking agent is too low, the absorption rate of the polymer may decrease and the gel strength may become weak, which is not preferred. On the contrary, when the concentration of the internal crosslinking agent is too high, the absorption capacity of the polymer may decrease, which is not preferred as an absorbent.

[0105] In addition, as needed, the monomer composition may further include additives such as thickeners, plasticizers, storage stabilizers, antioxidants, etc.

[0106] In addition, such a monomer composition can be prepared in the form of a solution in which raw materials such as the above-mentioned acrylic monomers, polymerization initiators, internal crosslinking agents, foaming agents, etc. are dissolved in a solvent.

[0107] In this regard, as a suitable solvent, any solvent can be used without limitation on the composition as long as it can dissolve the above-mentioned raw materials. For example, as the solvent, 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 amyl ketone, cyclohexanone, cyclopentanone, diethylene glycol monomethyl ether, diethylene glycol ethyl ether, toluene, xylene, butyrolactone, carbitol, methyl cellosolve acetate, N,N-dimethylacetamide or a mixture thereof can be used.

[0108] The formation of the hydrogel polymer by polymerization of the monomer composition can be carried out by common polymerization methods and the process is not particularly limited.

[0109] For non-limiting examples, the polymerization methods can be roughly classified into thermal polymerization and photo-polymerization according to the polymerization energy source. When performing thermal polymerization, it can be carried out in a reactor such as a kneader equipped with a stirring mandrel, while when performing photo-polymerization, it can be carried out in a reactor equipped with a movable conveyor belt.

[0110] For example, a monomer composition is injected into a reactor (such as a kneader equipped with a stirring mandrel), and thermal polymerization is carried out by supplying hot air to it or by heating the reactor, thereby obtaining a hydrogel polymer. In this regard, depending on the type of stirring mandrel equipped in the reactor, the hydrogel polymer discharged from the outlet of the reactor can be obtained as particles with dimensions of several centimeters or several millimeters. Specifically, the hydrogel polymer can be obtained in various forms according to the concentration, feeding rate, etc. of the monomer composition fed to it, and generally, a hydrogel polymer with a (weight-average) particle size of 2 mm to 50 mm can be obtained.

[0111] Another example is that when the monomer composition undergoes photo-polymerization in a reactor equipped with a movable conveyor belt, the hydrogel polymer can be obtained in the shape of a sheet. In this regard, the thickness of the sheet can vary according to the concentration and feeding rate of the monomer composition fed to it. It is preferable to control the sheet to a thickness of 0.5 cm to 10 cm to ensure the production speed while enabling uniform polymerization of the entire sheet.

[0112] The hydrogel polymer obtained by this method can exhibit a water content of 40 wt% to 80 wt%. Here, the water content refers to the weight occupied by water relative to the total weight of the hydrogel polymer, which can be a value obtained by subtracting the weight of the dry polymer from the weight of the hydrogel polymer. Specifically, the water content can be defined as a value calculated by measuring the weight loss caused by the evaporation of water in the polymer during the drying process of raising the temperature of the polymer by infrared heating. At this time, the drying conditions can be set as follows: raise the temperature from room temperature to 180 °C, then keep the temperature at 180 °C, and set the total drying time to 20 minutes, including 5 minutes for the temperature increase step.

[0113] In Step 1, the hydrogel polymer can be prepared in sheet form.

[0114] (Step 2)

[0115] Step 2 of the present invention is a step of forming a base polymer powder by coarsely crushing, drying, pulverizing, and classifying the sheet-like hydrogel polymer prepared in Step 1.

[0116] Specifically, in order to improve the drying efficiency of the hydrogel polymer and affect various physical properties of the superabsorbent polymer (including the absorption rate), especially to improve the absorption rate of the superabsorbent polymer by affecting the morphology of the superabsorbent polymer, the present invention may further include the step of coarsely crushing the hydrogel polymer before drying the hydrogel polymer. Hereinafter, in order to distinguish it from the crushing after drying, the term "coarse crushing" is used herein for convenience to refer to the crushing before drying.

[0117] The crusher for coarse crushing may include, but is not limited in structure to, specifically, any one selected from the group consisting of a vertical crusher, a turbo cutter, a turbo grinder, a rotary cutter mill, a cutter mill, a disk mill, a shredder, a crusher, a meat grinder, and a disk cutter, but is not limited to the above examples. Specifically, in the coarse crushing of the present invention, a meat grinder can be used.

[0118] At this time, the coarse crushing step can be carried out so that the hydrogel polymer has a particle size of about 2 mm to about 20 mm. Due to the high water content of the hydrogel polymer, it is not technically easy to crush the hydrogel polymer into a particle size less than 2 mm, and agglomeration may occur between the crushed particles. On the contrary, when the hydrogel polymer is crushed into a particle size greater than 20 mm, the effect of improving the efficiency in the subsequent drying step may be poor. Specifically, the coarse crushing step can be carried out using a meat grinder with holes of 15 mm to 17 mm.

[0119] In addition, a chelating agent can be mixed with the hydrogel polymer in the coarse crushing step. Specifically, the chelating agent can be mixed in such a way that the sheet-shaped hydrogel polymer prepared in step 1 is finely cut and ground while spraying the chelating agent.

[0120] The chelating agent can be mixed in an aqueous solution or powder state.

[0121] The chelating agent may include aminoacetate chelating agents.

[0122] The aminoacetate chelating agents may include one or more selected from the group consisting of ethylenediaminetetraacetic acid (EDTA), L-glutamic acid diacetic acid (GLDA), methylglycine diacetic acid (MGDA), hydroxyethyl ethylenediamine triacetic acid (HEDTA), ethanol diglycine (ethanolamine diacetic acid, EDG), diethylenetriaminepentaacetic acid (DTPA), and their salts.

[0123] Based on 100 parts by weight of the base polymer, the content of the chelating agent can be 0.05 to 4.0 parts by weight based on the solid content. Specifically, based on 100 parts by weight of the base polymer, the content of the chelating agent can be 0.05 parts by weight or more, 0.1 parts by weight or more, 0.3 parts by weight or more, 0.5 parts by weight or more, 0.7 parts by weight or more, or 1.0 parts by weight or more, and 4.0 parts by weight or less, 3.0 parts by weight or less, 2.0 parts by weight or less, 1.5 parts by weight or less, or 1.3 parts by weight or less.

[0124] In order to suppress bacterial growth at the level desired in the present invention and minimize the deterioration of physical properties caused by the introduction of the chelating agent while maintaining the inherent absorption properties of the superabsorbent polymer, it is preferable to include the chelating agent within the above content range.

[0125] Drying can be carried out at a temperature of 120°C to 250°C, 140°C to 200°C, or 150°C to 190°C. At this time, the drying temperature can be defined as the temperature of the heating medium provided for drying or the internal temperature of the drying reactor containing the heating medium and the polymer during the drying process. When the drying temperature is low and the drying time is long, the process efficiency decreases. To prevent this, the drying temperature is preferably 120°C or more. In addition, when the drying temperature is higher than the required temperature, the surface of the hydrogel polymer may be over-dried, which may increase the generation of fine powder in the subsequent pulverization step, and the physical properties of the final polymer may deteriorate. To prevent this, the drying temperature is preferably 250°C or less.

[0126] At this time, the drying time in the drying step is not particularly limited, but considering the process efficiency and physical properties of the polymer, it can be adjusted to 20 minutes to 90 minutes at the drying temperature.

[0127] Drying can be carried out using common media. For example, it can be carried out by methods such as supplying hot air, infrared radiation, microwave radiation, or ultraviolet radiation to the pulverized hydrogel polymer.

[0128] In addition, it is preferable to carry out drying so that the dried polymer has a water content of 0.1 wt% to 10 wt%. In other words, when the water content of the dried polymer is less than 0.1 wt%, over-drying may increase the production cost and may cause degradation of the crosslinked polymer, which is not preferable. In addition, when the water content of the dried polymer is greater than 10 wt%, defects may occur in the subsequent process, which is not preferable.

[0129] Subsequently, the dried hydrogel polymer can be pulverized. This is a step to optimize the surface area of the base polymer powder and the superabsorbent polymer. Pulverization can be carried out so that the particle size of the pulverized polymer is 150 μm to 850 μm.

[0130] In this regard, applicable grinders may include common grinders such as pin mills, hammer mills, screw mills, roller mills, disk mills, or joggling mills, etc.

[0131] In addition, in order to control the physical properties of the finally commercialized superabsorbent polymer, a step of selectively classifying particles with a particle size of 150 μm to 850 μm from the polymer particles obtained through the grinding step is carried out.

[0132] Through the above classification step, a base polymer powder can be obtained. The base polymer powder can have a particle size of 150 μm to 850 μm and can include fine powder with a particle size of less than 150 μm at 2 wt% or less or 1 wt% or less.

[0133] (Step 3)

[0134] Step 3 of the present invention is a step of mixing the base polymer powder prepared in Step 2 with a surface crosslinking agent.

[0135] The surface crosslinking agent used in Step 3 includes a surface crosslinking solution, and the surface crosslinking agent is not particularly limited as long as it is a surface crosslinking agent commonly used for surface crosslinking of superabsorbent polymers and is a compound capable of reacting with the functional groups of the polymer.

[0136] Preferably, in order to improve the performance of the superabsorbent polymer to be prepared, one or more selected from the group consisting of the following can be used as the surface crosslinking agent: polyols; epoxy compounds; polyamine compounds; halogenated epoxy compounds; condensation products of halogenated epoxy compounds; oxazoline compounds; mono-, di- or polyoxazolidinone compounds; cyclic urea compounds; polyvalent metal salts; and alkylene carbonate compounds.

[0137] Specifically, as examples of polyol compounds, one or more selected from the group consisting of the following can be used: mono-, di-, tri-, tetra- or polyethylene glycol, monopropylene glycol, 1,3 - propanediol, dipropylene glycol, 2,3,4 - trimethyl - 1,3 - pentanediol, polypropylene glycol, glycerol, polyglycerol, 2 - butene - 1,4 - diol, 1,4 - butanediol, 1,3 - butanediol, 1,5 - pentanediol, 1,6 - hexanediol, and 1,2 - cyclohexanedimethanol.

[0138] In addition, ethylene glycol diglycidyl ether and glycidol, etc. can be used as epoxy compounds, and one or more selected from the group consisting of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, polyethyleneimine, and polyamide polyamine can be used as polyamine compounds.

[0139] In addition, as the halogenated epoxy compound, epichlorohydrin, epibromohydrin, and α-methyl epichlorohydrin can be used. Meanwhile, as the mono-, di-, or polyoxazolidinone compound, 2-oxazolidinone can be used, for example.

[0140] In addition, as the alkylene carbonate compound, ethylene carbonate, etc. can be used. These compounds can be used alone or in combination. Meanwhile, in order to improve the efficiency of the surface crosslinking process, it is preferable to include one or more C2 to C10 polyol compounds in the surface crosslinking agent.

[0141] The content of the surface crosslinking agent to be added can be appropriately selected according to the type of the surface crosslinking agent to be added or the reaction conditions. However, generally, the amount used can be about 0.001 parts by weight to about 5 parts by weight, preferably about 0.01 parts by weight to about 3 parts by weight, and more preferably about 0.05 parts by weight to about 2 parts by weight relative to 100 parts by weight of the polymer.

[0142] When the content of the surface crosslinking agent is too small, the surface crosslinking reaction may hardly occur, while when the content relative to 100 parts by weight of the polymer exceeds 5 parts by weight, deterioration of the absorption capacity and physical properties may occur due to the progress of the excessive surface crosslinking reaction.

[0143] Meanwhile, the step of forming the surface crosslinked layer can be carried out by further including an inorganic material in the surface crosslinking agent. As such an inorganic material, one or more inorganic materials selected from the group consisting of silica, clay, alumina, silica-alumina composite, titanium dioxide, zinc oxide, and aluminum sulfate can be used. The inorganic material can be used in the form of powder or liquid, particularly in the form of alumina powder, silica-alumina powder, titanium dioxide powder, or nano-silica solution. In addition, the amount used of the inorganic material can be about 0.001 parts by weight to about 1 part by weight relative to 100 parts by weight of the base polymer.

[0144] Meanwhile, for the method of mixing the surface crosslinking agent with the base polymer, the method is not particularly limited as long as it is a method of uniformly mixing the surface crosslinking agent with the base polymer, and an appropriate method is selected and used.

[0145] For example, a method of adding and mixing the surface crosslinking agent and the base polymer powder in a reactor, a method of spraying the surface crosslinking agent onto the base polymer, a method of mixing them by continuously feeding the base polymer and the surface crosslinking agent into a continuously operating mixer, etc. can be used.

[0146] In this regard, the surface crosslinking agent can be an aqueous solution, and when the solid content in the solution is 1 wt% or more, 3 wt% or more, 5 wt% or more, 10 wt% or more, or 50 wt% or less, 30 wt% or less, or 20 wt% or less, it is suitable for uniform distribution in the base polymer and can simultaneously prevent agglomeration of the base polymer.

[0147] (Step 4)

[0148] Step 4 is a step of further improving the physical properties of the superabsorbent polymer by reacting the base polymer with a surface crosslinking agent to form an interpenetrating polymer network on the surface of the crosslinked polymer contained in the base polymer. Through this surface modification, a surface crosslinked layer is formed on the surface of the crushed base polymer particles.

[0149] The formation of the surface crosslinked layer can be carried out by common methods of increasing the crosslinking density of the surface of the polymer particles. For example, a method of carrying out a crosslinking reaction by mixing a surface crosslinking agent solution containing a surface crosslinking agent with the crushed polymer and performing heat treatment.

[0150] Step 4 can be carried out at a temperature of about 80°C to about 250°C. More specifically, the surface crosslinking process can be carried out at a temperature of about 100°C to about 220°C, or about 110°C to about 200°C, or at a temperature of about 120°C to about 190°C for about 10 minutes to about 2 hours, or about 20 minutes to about 60 minutes. If the crosslinking reaction temperature is lower than 160°C or the reaction time is too short, the surface crosslinking reaction cannot occur properly, so the permeability may decrease. When the temperature is higher than 200°C or the reaction time is too long, there may be a problem that the water retention capacity may decrease.

[0151] The heating device for the surface crosslinking reaction is not particularly limited. Heating can be carried out by providing a heating medium or by directly providing a heat source. In this regard, the types of applicable heating media can be steam, hot air, hot fluid (such as hot oil), etc., but the present invention is not limited thereto. The temperature of the heating medium to be provided can be appropriately selected considering the means of the heating medium, the heating rate, and the heating target temperature. At the same time, as the directly provided heat source, an electric heating or gas heating method can be used, but the present invention is not limited to the above examples.

[0152] In addition, the superabsorbent polymer on which the surface crosslinked layer is formed can be mixed with tannic acid, iodine compounds, and chelating agents. Tannic acid and iodine compounds chemically react with volatile unpleasant odor substances such as aldehydes, thereby providing the superabsorbent polymer with deodorizing ability.

[0153] Based on 100 parts by weight of the base polymer, the mixing amount of tannic acid based on the solid content can be greater than 0.001 part by weight to 0.5 part by weight, particularly greater than 0.001 part by weight, 0.002 part by weight or more, 0.003 part by weight or more, 0.005 part by weight or more, 0.01 part by weight or more, 0.015 part by weight or more, or 0.02 part by weight or more, and 0.5 part by weight or less, 0.3 part by weight or less, 0.1 part by weight or less, 0.07 part by weight or less, 0.05 part by weight or less, 0.04 part by weight or less, or 0.03 part by weight or less.

[0154] Based on 100 parts by weight of the base polymer, the mixing amount of the iodine compound can be 0.01 part by weight to 1.0 part by weight, particularly 0.01 part by weight or more, 0.03 part by weight or more, 0.05 part by weight or more, 0.07 part by weight or more, or 0.1 part by weight or more, and 1 part by weight or less, 0.8 part by weight or less, 0.5 part by weight or less, or 0.3 part by weight or less.

[0155] In order to exhibit the deodorizing ability at the level desired to be achieved in the present invention while maintaining the inherent absorption performance of the superabsorbent polymer, it is preferable to include tannic acid or an iodine compound within the above content range as a deodorizing material.

[0156] The deodorizing material containing tannic acid and an iodine compound can be mixed with the base polymer and the surface crosslinking agent in an aqueous solution or powder state.

[0157] In addition, the type of chelating agent to be mixed, the amount to be mixed, and the description of the mixing form are as described in Step 1.

[0158] In addition, additional additives can be further mixed with the superabsorbent polymer on which a surface crosslinking layer is formed. The additional additives can also include one or more additives selected from the group consisting of organic acids, glycerin, and zinc chloride.

[0159] The organic acid can be one or more selected from the group consisting of citric acid, glycine, acetic acid, formic acid, fumaric acid, lactic acid, and propionic acid. Specifically, the organic acid can be citric acid or glycine. The organic acid can exhibit a deodorizing effect in the superabsorbent polymer together with the deodorizing material.

[0160] The organic acid, glycerin, and zinc chloride can be mixed in an aqueous solution in which water is used as a solvent or in a powder state.

[0161] When the deodorizing material and the chelating agent are added to the superabsorbent polymer on which a surface crosslinking layer is formed as an aqueous solution, an additional drying step can be further performed.

[0162] In the following, preferred exemplary embodiments will be provided to better understand the present invention. However, the following exemplary embodiments are only for illustrating the present invention, and the present invention is not limited thereto.

[0163] The sources of the reagents used in the following comparative examples and examples are as follows.

[0164] Aqueous EDTA solution: Daejung Chemicals&Metals Co.,Ltd.

[0165] Aqueous tannic acid solution: Samchun Chemical Co.,Ltd.

[0166] Iodine solution: Bookwang Tech Co.,Ltd.

[0167] Aqueous glycerol solution: Sigma-Aldrich

[0168] Aqueous glycine solution: Sigma-Aldrich

[0169] Comparative Example 1

[0170] 100 g of acrylic acid, 0.37 g of N,N'-methylenebisacrylamide as a crosslinking agent, 0.15 g of sodium persulfate (SPS) as a thermal initiator, 0.008 g of benzoin ether as a UV initiator, 40 g of caustic soda (NaOH), and 127 g of water were mixed to prepare a monomer aqueous solution composition having a monomer concentration of 45.8% by weight. The monomer aqueous solution composition was fed into the feed zone of a polymerization reactor equipped with a continuously moving conveyor belt, and then irradiated with UV by a UV irradiation device (irradiation dose: 10 mW / cm 2 ), while maintaining the polymerization atmosphere temperature at 80 °C, and UV polymerization was carried out for 2 minutes to prepare a sheet-like hydrogel polymer.

[0171] The hydrogel polymer was chopped using a meat grinder having a 16 mm hole. At this time, the chopped hydrogel polymer had a water content of 47% by weight. Subsequently, the hydrogel polymer was dried in a hot air dryer at 185 °C for 30 minutes, and the dried hydrogel polymer was pulverized with a needle mill, and then the polymer having a particle size of 150 μm to 850 μm was classified using a sieve to prepare a base polymer.

[0172] Thereafter, a surface crosslinking agent (2.5 parts by weight of water, 0.1 part by weight of ethylene glycol diglycidyl ether (EX-810), 0.1 part by weight of aluminum sulfate 18-hydrate (Al-S), and 0.1 part by weight of silica (Aerosil A200)) was uniformly mixed with 100 parts by weight of the prepared base polymer, and then a surface crosslinking reaction was carried out at 140 °C for 30 minutes. After completion of the surface treatment, a superabsorbent polymer having a particle size of 150 μm to 850 μm was obtained using a sieve.

[0173] Example 1

[0174] 100 g of acrylic acid, 0.37 g of N,N'-methylenebisacrylamide as a crosslinking agent, 0.15 g of sodium persulfate (SPS) as a thermal initiator, 0.008 g of benzoin ether as a UV initiator, 40 g of caustic soda (NaOH), and 127 g of water were mixed to prepare a monomer aqueous solution composition having a monomer concentration of 45.8% by weight. The monomer aqueous solution composition was fed into the feed zone of a polymerization reactor equipped with a continuously moving conveyor belt, and then irradiated with UV by a UV irradiation device (irradiation dose: 10 mW / cm 2 ), while maintaining the polymerization atmosphere temperature at 80 °C, and UV polymerization was carried out for 2 minutes to prepare a sheet-like hydrogel polymer.

[0175] The hydrogel polymer was chopped using a meat grinder having 16 mm holes. At this time, the chopped hydrogel polymer had a water content of 47% by weight. Subsequently, the hydrogel polymer was dried in a hot air dryer at 185 °C for 30 minutes, and the dried hydrogel polymer was pulverized using a needle mill, and then a polymer having a particle size of 150 μm to 850 μm was classified using a sieve to prepare a base polymer.

[0176] Thereafter, a surface crosslinking agent (2.5 parts by weight of water, 0.1 part by weight of ethylene glycol diglycidyl ether (EX-810), 0.1 part by weight of aluminum sulfate 18-hydrate (Al-S), and 0.1 part by weight of silica (Aerosil A200)) was uniformly mixed with 100 parts by weight of the prepared base polymer, and then a surface crosslinking reaction was carried out at 140 °C for 30 minutes. After completion of the surface treatment, a superabsorbent polymer having a particle size of 150 μm to 850 μm was obtained using a sieve.

[0177] The surface-treated superabsorbent polymer was mixed with EDTA, tannic acid, iodine solution, and glycerin in an aqueous solution state. An EDTA aqueous solution having a concentration of 40% was used. A tannic acid aqueous solution having a tannic acid solid content of 5 parts by weight (based on 100 parts by weight of the aqueous solution) was used. An iodine solution having a concentration of 0.1% (liquid I2) was used.

[0178] Mix EDTA with a solid content of 0.5 parts by weight (relative to 100 parts by weight of the base polymer), tannic acid with a solid content of 0.015 parts by weight (relative to 100 parts by weight of the base polymer), and an iodine solution of 0.1 parts by weight (relative to 100 parts by weight of the base polymer). Then, perform a drying step at 80 °C for 25 minutes.

[0179] Example 2

[0180] Prepare the surface-treated superabsorbent polymer in the same manner as in Example 1.

[0181] Mix the surface-treated superabsorbent polymer with EDTA, tannic acid, and an iodine solution in an aqueous solution state. Use an aqueous EDTA solution with a solid content of 40%. Use an aqueous tannic acid solution with a tannic acid solid content of 5 parts by weight (based on 100 parts by weight of the aqueous solution). Use an iodine solution with a concentration of 0.1% (liquid I2).

[0182] Mix EDTA with a solid content of 0.5 parts by weight (relative to 100 parts by weight of the base polymer), tannic acid with a solid content of 0.05 parts by weight (relative to 100 parts by weight of the base polymer), and an iodine solution of 0.1 parts by weight (relative to 100 parts by weight of the base polymer). Then, perform a drying step at 80 °C for 25 minutes.

[0183] Example 3

[0184] Prepare the surface-treated superabsorbent polymer in the same manner as in Example 1.

[0185] Mix the surface-treated superabsorbent polymer with EDTA, tannic acid, and an iodine solution in an aqueous solution state. Use an aqueous EDTA solution with a solid content of 40%. Use an aqueous tannic acid solution with a tannic acid solid content of 5 parts by weight (based on 100 parts by weight of the aqueous solution). Use an iodine solution with a concentration of 0.1% (liquid I2).

[0186] Mix EDTA with a solid content of 0.5 parts by weight (relative to 100 parts by weight of the base polymer), tannic acid with a solid content of 0.1 parts by weight (relative to 100 parts by weight of the base polymer), and an iodine solution of 0.1 parts by weight (relative to 100 parts by weight of the base polymer). Then, perform a drying step at 80 °C for 25 minutes.

[0187] Example 4

[0188] Prepare the surface-treated superabsorbent polymer in the same manner as in Example 1.

[0189] Mix the surface-treated superabsorbent polymer with aqueous solutions of EDTA, tannic acid, and iodine solution. Use an EDTA aqueous solution with a solid content of 40%. Use a tannic acid aqueous solution with a tannic acid solid content of 5 parts by weight (based on 100 parts by weight of the aqueous solution). Use an iodine solution with a concentration of 0.1% (liquid I2).

[0190] Mix 0.1 part by weight of EDTA (relative to 100 parts by weight of the base polymer) with a solid content, 0.015 part by weight of tannic acid (relative to 100 parts by weight of the base polymer) with a solid content, and 0.1 part by weight of iodine solution (relative to 100 parts by weight of the base polymer). Then, conduct a drying step at 80 °C for 25 minutes.

[0191] Example 5

[0192] Prepare the surface-treated superabsorbent polymer in the same manner as in Example 1.

[0193] Mix the surface-treated superabsorbent polymer with aqueous solutions of EDTA, tannic acid, and iodine solution. Use an EDTA aqueous solution with a solid content of 40%. Use a tannic acid aqueous solution with a tannic acid solid content of 5 parts by weight (based on 100 parts by weight of the aqueous solution). Use an iodine solution with a concentration of 0.1% (liquid I2).

[0194] Mix 1 part by weight of EDTA (relative to 100 parts by weight of the base polymer) with a solid content, 0.015 part by weight of tannic acid (relative to 100 parts by weight of the base polymer) with a solid content, and 0.1 part by weight of iodine solution (relative to 100 parts by weight of the base polymer). Then, conduct a drying step at 80 °C for 25 minutes.

[0195] Example 6

[0196] Prepare the surface-treated superabsorbent polymer in the same manner as in Example 1.

[0197] Mix the surface-treated superabsorbent polymer with aqueous solutions of EDTA, tannic acid, and iodine solution. Use an EDTA aqueous solution with a solid content of 40%. Use a tannic acid aqueous solution with a tannic acid solid content of 5 parts by weight (based on 100 parts by weight of the aqueous solution). Use an iodine solution with a concentration of 0.1% (liquid I2).

[0198] Mix 2 parts by weight of EDTA (relative to 100 parts by weight of the base polymer) with a solid content, 0.015 part by weight of tannic acid (relative to 100 parts by weight of the base polymer) with a solid content, and 0.1 part by weight of iodine solution (relative to 100 parts by weight of the base polymer). Then, conduct a drying step at 80 °C for 25 minutes.

[0199] Example 7

[0200] The surface-treated superabsorbent polymer was prepared in the same manner as in Example 1.

[0201] The surface-treated superabsorbent polymer was mixed with an aqueous solution of EDTA, tannic acid, and iodine solution. An EDTA aqueous solution with a solid content of 40% was used. A tannic acid aqueous solution with a tannic acid solid content of 5 parts by weight (based on 100 parts by weight of the aqueous solution) was used. An iodine solution with a concentration of 0.1% (liquid I2) was used.

[0202] EDTA with a solid content of 0.5 part by weight (relative to 100 parts by weight of the base polymer), tannic acid with a solid content of 0.015 part by weight (relative to 100 parts by weight of the base polymer), and 0.05 part by weight (relative to 100 parts by weight of the base polymer) of the iodine solution were mixed. Then, a drying step was carried out at 80 °C for 25 minutes.

[0203] Example 8

[0204] The surface-treated superabsorbent polymer was prepared in the same manner as in Example 1.

[0205] The surface-treated superabsorbent polymer was mixed with an aqueous solution of EDTA, tannic acid, and iodine solution. An EDTA aqueous solution with a solid content of 40% was used. A tannic acid aqueous solution with a tannic acid solid content of 5 parts by weight (based on 100 parts by weight of the aqueous solution) was used. An iodine solution with a concentration of 0.1% (liquid I2) was used.

[0206] EDTA with a solid content of 0.5 part by weight (relative to 100 parts by weight of the base polymer), tannic acid with a solid content of 0.015 part by weight (relative to 100 parts by weight of the base polymer), and 0.5 part by weight (relative to 100 parts by weight of the base polymer) of the iodine solution were mixed. Then, a drying step was carried out at 80 °C for 25 minutes.

[0207] Example 9

[0208] A sheet-like hydrogel polymer was prepared in the same manner as in Example 1.

[0209] The sheet-like hydrogel polymer was finely cut, and the finely cut hydrogel polymer was shredded (hole size 16 mm) and mixed while spraying an EDTA aqueous solution (concentration 40%). At this time, EDTA was mixed with a solid content of 0.5 part by weight based on 100 parts by weight of the base polymer.

[0210] At this time, the shredded hydrogel polymer has a water content of 47% by weight. Subsequently, the hydrogel polymer is dried in a hot air dryer at 185 °C for 30 minutes, and the dried hydrogel polymer is pulverized with a needle mill. Subsequently, the polymer with a particle size of 150 μm to 850 μm is separated by sieving to prepare a base polymer.

[0211] Thereafter, a surface crosslinking agent (2.5 parts by weight of water, 0.1 part by weight of ethylene glycol diglycidyl ether (EX-810), 0.1 part by weight of aluminum sulfate 18-hydrate (Al-S), and 0.1 part by weight of silica (Aerosil A200)) is uniformly mixed with 100 parts by weight of the prepared base polymer, and then a surface crosslinking reaction is carried out at 140 °C for 30 minutes. After completion of the surface treatment, a superabsorbent polymer with a particle size of 150 μm to 850 μm is obtained using a sieve.

[0212] The surface-treated superabsorbent polymer is mixed with an aqueous solution of tannic acid and an iodine solution. An aqueous tannic acid solution with a tannic acid solid content of 5 parts by weight (based on 100 parts by weight of the aqueous solution) is used. An iodine solution with a concentration of 0.1% (liquid I2) is used.

[0213] 0.015 part by weight of tannic acid (relative to 100 parts by weight of the base polymer) and 0.5 part by weight of the iodine solution (relative to 100 parts by weight of the base polymer) are mixed. Then, a drying step is carried out at 80 °C for 25 minutes.

[0214] Example 10

[0215] A surface-treated superabsorbent polymer is prepared in the same manner as in Example 1.

[0216] The surface-treated superabsorbent polymer is mixed with an aqueous solution of EDTA, tannic acid, and an iodine solution. An aqueous EDTA solution with a solid content of 40% is used. An aqueous tannic acid solution with a tannic acid solid content of 5 parts by weight (based on 100 parts by weight of the aqueous solution) is used. An iodine solution with a concentration of 0.1% (liquid I2) is used.

[0217] 0.5 part by weight of EDTA (relative to 100 parts by weight of the base polymer), 0.015 part by weight of tannic acid (relative to 100 parts by weight of the base polymer), and 0.1 part by weight of the iodine solution (relative to 100 parts by weight of the base polymer) are mixed. Then, a drying step is carried out at 80 °C for 25 minutes.

[0218] Example 11

[0219] A surface-treated superabsorbent polymer is prepared in the same manner as in Example 1.

[0220] Mix the surface-treated superabsorbent polymer with EDTA, tannic acid, iodine solution, and glycine in aqueous solution state. Use an EDTA aqueous solution with a solid content of 40%. Use a tannic acid aqueous solution with a tannic acid solid content of 5 parts by weight (based on 100 parts by weight of the aqueous solution). Use an iodine solution (liquid I2) with a concentration of 0.1%. Use a glycine aqueous solution with a concentration of 10%.

[0221] Mix 0.5 part by weight of EDTA (relative to 100 parts by weight of the base polymer) with a solid content, 0.015 part by weight of tannic acid (relative to 100 parts by weight of the base polymer) with a solid content, 0.1 part by weight of iodine solution (relative to 100 parts by weight of the base polymer), and 0.018 part by weight of glycine (relative to 100 parts by weight of the base polymer) with a solid content. Then, perform a drying step at 80 °C for 25 minutes.

[0222] Example 12

[0223] Prepare the surface-treated superabsorbent polymer in the same manner as in Example 1.

[0224] Mix the surface-treated superabsorbent polymer with EDTA, tannic acid, iodine solution, and glycerol in aqueous solution state. Use an EDTA aqueous solution with a concentration of 40%. Use a tannic acid aqueous solution with a tannic acid solid content of 5 parts by weight (based on 100 parts by weight of the aqueous solution). Use an iodine solution (liquid I2) with a concentration of 0.1%. Use a glycerol aqueous solution with 10 parts by weight of glycerol (based on 100 parts by weight of the aqueous solution).

[0225] Mix 0.5 part by weight of EDTA (relative to 100 parts by weight of the base polymer) with a solid content, 0.015 part by weight of tannic acid (relative to 100 parts by weight of the base polymer) with a solid content, 0.1 part by weight of iodine solution (relative to 100 parts by weight of the base polymer), and 0.03 part by weight of glycerol (relative to 100 parts by weight of the base polymer) with a solid content. Then, perform a drying step at 80 °C for 25 minutes.

[0226] Comparative Example 2

[0227] Mix 100 g of acrylic acid, 0.37 g of N,N'-methylenebisacrylamide as a crosslinking agent, 0.15 g of sodium persulfate (SPS) as a thermal initiator, 0.008 g of benzoin ether as a UV initiator, 40 g of caustic soda (NaOH), and 127 g of water to prepare a monomer aqueous solution composition with a monomer concentration of 45.8% by weight. Feed the monomer aqueous solution composition into the feed zone of a polymerization reactor equipped with a continuously moving conveyor belt, and then irradiate with UV using a UV irradiation device (irradiation dose: 10 mW / cm 2) Meanwhile, maintain the polymerization atmosphere temperature at 80 °C and perform UV polymerization for 2 minutes to prepare a sheet-like hydrogel polymer.

[0228] Precisely cut the sheet-like hydrogel polymer, and chop the precisely cut hydrogel polymer (with a pore size of 16 mm) and mix it, while spraying an aqueous EDTA solution (concentration: 40%) onto it. At this time, EDTA is mixed with a solid content of 0.5 parts by weight (based on 100 parts by weight of the base polymer).

[0229] At this time, the chopped hydrogel polymer has a water content of 47% by weight. Subsequently, dry the hydrogel polymer in a hot air dryer at 185 °C for 30 minutes, and pulverize the dried hydrogel polymer with a needle mill. Then, use a sieve to classify out the polymer with a particle size of 150 μm to 850 μm to prepare the base polymer.

[0230] Thereafter, uniformly mix the surface crosslinking agent (2.5 parts by weight of water, 0.1 part by weight of ethylene glycol diglycidyl ether (EX-810), 0.1 part by weight of aluminum sulfate 18-hydrate (Al-S), and 0.1 part by weight of silica (Aerosil A200)) with 100 parts by weight of the prepared base polymer, and then perform a surface crosslinking reaction at 140 °C for 30 minutes. After completing the surface treatment, use a sieve to obtain the superabsorbent polymer with a particle size of 150 μm to 850 μm.

[0231] Comparative Example 3

[0232] Prepare the surface-treated superabsorbent polymer in the same manner as in Comparative Example 1.

[0233] Mix the surface-treated superabsorbent polymer with glycerol in an aqueous solution state. Use an aqueous glycerol solution with 10 parts by weight of glycerol (based on 100 parts by weight of the aqueous solution).

[0234] Mix 0.03 parts by weight of glycerol (relative to 100 parts by weight of the base polymer). Then, perform a drying step at 80 °C for 25 minutes.

[0235] Comparative Example 4

[0236] Prepare the surface-treated superabsorbent polymer in the same manner as in Comparative Example 1.

[0237] Mix the surface-treated superabsorbent polymer with tannic acid and glycerol in an aqueous solution state. Use an aqueous tannic acid solution with a solid content of 5 parts by weight of tannic acid (based on 100 parts by weight of the aqueous solution). Use an aqueous glycerol solution with 10 parts by weight of glycerol (based on 100 parts by weight of the aqueous solution).

[0238] Mix tannic acid with a solid content of 0.015 parts by weight (relative to 100 parts by weight of the base polymer) and glycerol with a solid content of 0.03 parts by weight (relative to 100 parts by weight of the base polymer). Then, perform a drying step at 80 °C for 25 minutes.

[0239] Comparative Example 5

[0240] Prepare the surface-treated superabsorbent polymer in the same manner as Comparative Example 1.

[0241] Mix the surface-treated superabsorbent polymer with EDTA and tannic acid in an aqueous solution state. Use an EDTA aqueous solution with a concentration of 40%. Use a tannic acid aqueous solution with a solid content of 5 parts by weight (based on 100 parts by weight of the aqueous solution).

[0242] Mix EDTA with a solid content of 0.5 parts by weight (relative to 100 parts by weight of the base polymer) and tannic acid with a solid content of 0.015 parts by weight (relative to 100 parts by weight of the base polymer). Then, perform a drying step at 80 °C for 25 minutes.

[0243] Comparative Example 6

[0244] Prepare the surface-treated superabsorbent polymer in the same manner as Comparative Example 1.

[0245] Mix the surface-treated superabsorbent polymer with glycine in an aqueous solution state. Use a glycine aqueous solution with a concentration of 10%.

[0246] Mix 0.018 parts by weight (relative to 100 parts by weight of the base polymer) of glycine. Then, perform a drying step at 80 °C for 25 minutes.

[0247] Comparative Example 7

[0248] Prepare the surface-treated superabsorbent polymer in the same manner as Comparative Example 1.

[0249] Mix the surface-treated superabsorbent polymer with EDTA and glycerol in an aqueous solution state. Use an EDTA aqueous solution with a concentration of 40%. Use a glycerol aqueous solution with a glycerol content of 10 parts by weight (based on 100 parts by weight of the aqueous solution).

[0250] Mix EDTA with a solid content of 0.5 parts by weight (relative to 100 parts by weight of the base polymer) and glycerol with a solid content of 0.03 parts by weight (relative to 100 parts by weight of the base polymer). Then, perform a drying step at 80 °C for 25 minutes.

[0251] Comparative Example 8

[0252] Prepare the surface-treated superabsorbent polymer in the same manner as Comparative Example 1.

[0253] Mix the surface-treated superabsorbent polymer with tannic acid in an aqueous solution state. Use an aqueous tannic acid solution with a solid content of 5 parts by weight (based on 100 parts by weight of the aqueous solution).

[0254] Mix tannic acid with a solid content of 0.015 parts by weight (relative to 100 parts by weight of the base polymer). Then, perform a drying step at 80 °C for 25 minutes.

[0255] Comparative Example 9

[0256] Prepare the surface-treated superabsorbent polymer in the same manner as in Comparative Example 1.

[0257] Mix the surface-treated superabsorbent polymer with an iodine solution (liquid I2). Use an aqueous solution with a concentration of 0.1% as the iodine solution.

[0258] Mix 0.1 part by weight (relative to 100 parts by weight of the base polymer) of the iodine solution. Then, perform a drying step at 80 °C for 25 minutes.

[0259] Comparative Example 10

[0260] Prepare the surface-treated superabsorbent polymer in the same manner as in Comparative Example 1.

[0261] Mix the surface-treated superabsorbent polymer with tannic acid and an iodine solution (liquid I2). Use an aqueous tannic acid solution with a solid content of 5 parts by weight (based on 100 parts by weight of the aqueous solution). Use an aqueous solution with a concentration of 0.1% as the iodine solution.

[0262] Mix tannic acid with a solid content of 0.015 parts by weight (relative to 100 parts by weight of the base polymer). Mix 0.1 part by weight (relative to 100 parts by weight of the base polymer) of the iodine solution. Then, perform a drying step at 80 °C for 25 minutes.

[0263] Comparative Example 11

[0264] Prepare the surface-treated superabsorbent polymer in the same manner as in Comparative Example 1.

[0265] Mix the surface-treated superabsorbent polymer with an aqueous EDTA solution and an iodine solution (liquid I2). Use an aqueous solution with a concentration of 40% as the aqueous EDTA solution. Use an aqueous solution with a concentration of 0.1% as the iodine solution.

[0266] Mix EDTA with a solid content of 0.5 parts by weight (relative to 100 parts by weight of the base polymer). Mix 0.1 part by weight (relative to 100 parts by weight of the base polymer) of the iodine solution. Then, perform a drying step at 80 °C for 25 minutes.

[0267] The conditions of the examples and comparative examples are summarized in Tables 1 and 2 below.

[0268] Table 1

[0269]

[0270] Table 2

[0271]

[0272] Experimental Example

[0273] For the superabsorbent polymer compositions prepared in the examples and comparative examples, each physical property was measured by the following method.

[0274] 1) Bacterial inhibition rate

[0275] 50 ml of artificial urine inoculated with 3000 CFU / ml of Escherichia coli was placed into 2 g of the EDTA-free superabsorbent polymer of Comparative Example 1, and cultivated in an incubator at 35 °C for 12 hours. The cultivated sample was thoroughly washed with 150 ml of saline solution (0.9 wt% aqueous sodium chloride solution), cultured on a nutrient broth agar (BD DIFCO.) plate, and the colony forming unit (CFU / ml) was measured, which was determined as the physical property of the control group.

[0276] 2 g of each superabsorbent polymer prepared in the examples or comparative examples was added to 50 ml of artificial urine inoculated with 3000 CFU / ml of Escherichia coli, and cultivated in an incubator at 35 °C for 12 hours. 150 ml of saline solution (0.9 wt% aqueous sodium chloride solution) was added to each of the cultivated samples, and uniformly mixed under shaking for 1 minute. The resulting dilution was spread on a nutrient broth agar (BD DIFCO.) plate, and cultivated in an incubator at 30 °C for 24 hours, and then the colony forming unit (CFU / ml) was measured.

[0277] Using each measurement result, the bacterial inhibition rate defined by the following Equation 1 was calculated, and based on this, the antibacterial activity of the superabsorbent polymers of the examples and comparative examples was evaluated:

[0278] [Equation 1]

[0279] Bacterial growth inhibition rate = [1 - {CFU(12 hr) / CFU control(12 hr)}] * 100 (%)

[0280] In Equation 1,

[0281] CFU(12hr) represents the number of proliferated bacterial individuals (CFU / ml) per unit volume of artificial urine, which is obtained by adding a superabsorbent polymer to artificial urine inoculated with Escherichia coli bacteria, followed by incubation at 35°C for 12 hours, and

[0282] CFU control (12hr) represents the number of proliferated bacterial individuals (CFU / ml) per unit volume of artificial urine, i.e., the number of bacterial individuals (CFU / ml) in the control group of artificial urine per unit volume, which is obtained by incubating artificial urine inoculated with bacteria in the superabsorbent polymer of EDTA under the same conditions.

[0283] 2) Deodorization rate

[0284] The deodorization rate is measured using an adsorbent tube test. 3-Methylbutyraldehyde, which is selected as an aldehyde-based malodorous substance, and dimethyl trisulfide (DMTS), which is selected as a sulfur compound-based malodorous substance, are used to test their deodorization capabilities.

[0285] - Adsorbent tube test: Place 1 g of the superabsorbent polymer into a 500 mL glass bottle, and then inject 25 mL of the malodorous substance. Thereafter, aging is carried out in a constant temperature chamber for 3 hours and collection is carried out for 20 minutes. At this time, the temperature of the constant temperature chamber is 35°C and the N2 flow rate is 250 mL / min. Then, the exhausted malodorous smell is adsorbed into the connected adsorbent tube, and the same sample is collected twice. The collected results are analyzed by GC to confirm the results.

[0286] - Deodorization ability (%) = (Amount of malodorous smell of the reference sample (superabsorbent polymer of Comparative Example 1) measured by GC - Amount of malodorous smell of the sample measured by GC) / Amount of malodorous smell of the reference sample (superabsorbent polymer of Comparative Example 1) measured by GC (%) X 100 (%)

[0287] 3) Centrifugal retention capacity (CRC)

[0288] The water retention capacity achieved by absorption of each polymer under no load is measured according to the European Disposables and Nonwovens Association (EDANA) standard EDANA WSP241.3.

[0289] Specifically, polymers with a particle size range of 300 μm to 600 μm were fractionated from each polymer obtained from the examples and comparative examples. Polymer W0 (g) (about 0.2 g) was evenly placed into a bag made of non-woven fabric and then sealed. Then, the bag was immersed in a physiological saline solution (0.9 wt%) at room temperature. After 30 minutes, water was removed from the bag using a centrifuge at 250 G for 3 minutes, and then the weight W2 (g) of the bag was measured. Additionally, the same procedure was carried out without using the polymer, and then the resulting weight W1 (g) was measured.

[0290] Using the corresponding weights thus obtained, the CRC (g / g) was calculated according to the following Equation 1.

[0291] [Equation 1]

[0292] CRC (g / g) = {[W2 (g) - W1 (g)] / W0 (g)} – 1

[0293] 4) Absorbency Under Pressure (AUP)

[0294] The absorbency under 0.7 psi pressure of the superabsorbent polymers of the examples and comparative examples was measured according to the EDANA method WSP 242.3.

[0295] First, when measuring the absorbency under pressure, the fractionated polymers used in the CRC measurement were employed.

[0296] Specifically, a 400-mesh steel mesh was installed at the bottom of a plastic cylinder with an inner diameter of 25 mm. Under the conditions of room temperature and 50% humidity, the superabsorbent polymer W0 (g) was evenly dispersed on the steel mesh. A piston capable of uniformly providing a 0.7 psi load was placed thereon, where the outer diameter of the piston was slightly smaller than 25 mm, there was no gap between the inner wall of the cylinder and the piston, and the slight movement of the cylinder was not interrupted. At this time, the weight W3 (g) of the measuring device was measured.

[0297] After placing a glass filter with a diameter of 90 mm and a thickness of 5 mm in a petri dish with a diameter of 150 mm, a physiological saline solution composed of 0.9 wt% sodium chloride was poured until the surface level of the physiological saline solution became flush with the upper surface of the glass filter. A filter paper with a diameter of 90 mm was placed on the glass filter. The measuring device was installed on the filter paper so that the liquid was absorbed under the load for 1 hour. After 1 hour, after lifting the measuring device, the weight W4 (g) was measured. The absorbency under pressure (g / g) was calculated using the obtained weights according to the following Equation 2.

[0298] [Equation 2]

[0299] AUP (g / g) = [W4 (g) – W3 (g)] / W0 (g)

[0300] 5) Gel strength (N)

[0301] From the superabsorbent polymers, those with particle sizes ranging from 150 μm to 850 μm were obtained. 2.5 g of the superabsorbent polymer was immersed in 50 g of ascorbate water and allowed to swell in an oven at 40 °C for 2 hours and 4 hours. Then, the gel strength of the swollen superabsorbent polymer was measured using a tensile-compression tester.

[0302] Specifically, a digital force gauge FGP-2 (which is a tensile-compression tester) was used to measure the swollen superabsorbent polymer, and the peak value of the force (N) applied to the tip when it was penetrated was measured three times under the following conditions. Then, the arithmetic mean was taken as the gel strength (unit: N).

[0303] Tip size: The end diameter is 10 ± 0.1 mm

[0304] Measuring cup size: 50 ± 0.1 mm

[0305] Penetration speed: 500 ± 0.5 mm / min

[0306] The experimental results are shown in Table 3.

[0307] Table 3

[0308]

[0309] According to the results in Table 3, it was confirmed that compared with Comparative Example 1 without additives, the examples had excellent antibacterial and deodorization rates while maintaining the absorbency at a similar level. It was also confirmed that Example 1 had excellent gel strength compared with Comparative Examples 1, 2, and 8.

[0310] In addition, Comparative Example 2, which used only a chelating agent without a deodorizing material, showed a similar level of antibacterial rate while showing a very poor deodorization rate, and Comparative Example, which used only a deodorizing material without a chelating agent, did not inhibit bacteria at all, and their deodorization rates also tended to be lower compared with the examples.

[0311] On the contrary, it was confirmed that different from those superabsorbent polymers of the comparative examples, the superabsorbent polymers of the examples did not show deterioration of the absorbency (which is an inherent physical property of superabsorbent polymers), while having excellent antibacterial and deodorization rates and maintaining excellent gel strength.

[0312] It is speculated that the iodide ions of the iodine compound contained in the examples change the ascorbic acid component in urine and body fluids and block the gel inhibition function of ascorbic acid. In addition, since it is known that a chelating agent contributes to the gel strength improvement effect to some extent by combining with metal ions, it was confirmed that the gel strength was improved by their combination.

Claims

1. A superabsorbent polymer composition, comprising: Superabsorbent polymer, comprising: A base polymer, which is a crosslinked polymer formed by crosslinking polymerization of acrylic monomers having at least partially neutralized acidic groups and an internal crosslinking agent; And a surface crosslinked layer formed on the surface of the base polymer, wherein the crosslinked polymer is additionally crosslinked via a surface crosslinking agent; Tannic acid; An iodine compound; and A chelating agent.

2. The superabsorbent polymer composition according to claim 1, wherein, relative to 100 parts by weight of the base polymer, the content of the tannic acid is greater than 0.001 part by weight to 0.5 part by weight in terms of solid content.

3. The superabsorbent polymer composition according to claim 1, wherein, relative to 100 parts by weight of the base polymer, the content of the iodine compound is 0.01 part by weight to 1.0 part by weight.

4. The superabsorbent polymer composition according to claim 1, wherein, relative to 100 parts by weight of the base polymer, the content of the chelating agent is 0.05 part by weight to 4.0 part by weight in terms of solid content.

5. The superabsorbent polymer composition according to claim 1, wherein the chelating agent comprises an aminoacetate chelating agent.

6. The superabsorbent polymer composition according to claim 5, wherein the aminoacetate chelating agent comprises one or more selected from the group consisting of ethylenediaminetetraacetic acid (EDTA), L-glutamic acid diacetic acid (GLDA), methylglycine diacetic acid (MGDA), hydroxyethyl ethylenediamine triacetic acid (HEDTA), ethanolamine diacetic acid (EDG), diethylenetriamine pentaacetic acid (DTPA), and their salts.

7. The superabsorbent polymer composition according to claim 1, which further comprises one or more additives selected from the group consisting of organic acids, glycerol, and zinc chloride.

8. The superabsorbent polymer composition according to claim 1, wherein the tannic acid and the iodine compound are separately included from the superabsorbent polymer, and The chelating agent is included in the base polymer or is separately included from the superabsorbent polymer.

9. A method for preparing a superabsorbent polymer composition, the method comprising the following steps: Step 1: Forming a hydrogel polymer by crosslinking polymerization of acrylic monomers having at least partially neutralized acidic groups in the presence of an internal crosslinking agent and a polymerization initiator; Step 2: Preparing a base polymer containing a crosslinked polymer by coarsely crushing, drying, and pulverizing the hydrogel polymer; Step 3: Preparing a mixture by mixing the base polymer with a surface crosslinking agent; and Step 4: Preparing a superabsorbent polymer by heat-treating the mixture, wherein a surface crosslinked layer is formed on the surface of the base polymer; Wherein tannic acid and an iodine compound are mixed with the superabsorbent polymer of Step 4 on which the surface crosslinked layer is formed, and the chelating agent is mixed in the coarsely crushing step of Step 2 or is mixed with the superabsorbent polymer of Step 4 on which the surface crosslinked layer is formed.

10. The method according to claim 9, wherein the mixing amount of the tannic acid is greater than 0.001 parts by weight to 0.1 parts by weight in terms of solid content based on 100 parts by weight of the base polymer.

11. The method according to claim 9, wherein the mixing amount of the iodine compound is 0.01 parts by weight to 1.0 parts by weight based on 100 parts by weight of the base polymer.

12. The method according to claim 9, wherein the mixing amount of the chelating agent is 0.05 parts by weight to 4.0 parts by weight in terms of solid content based on 100 parts by weight of the base polymer.

13. The method according to claim 9, wherein the chelating agent comprises an aminoacetate chelating agent.

14. The method according to claim 13, wherein the aminoacetate chelating agent comprises one or more selected from the group consisting of ethylenediaminetetraacetic acid (EDTA), L-glutamic acid diacetic acid (GLDA), methylglycine diacetic acid (MGDA), hydroxyethyl ethylenediamine triacetic acid (HEDTA), ethanolamine diacetic acid (EDG), diethylenetriaminepentaacetic acid (DTPA), and salts thereof.

15. The method according to claim 9, wherein after step 4, the superabsorbent polymer having a surface crosslinked layer is further mixed with one or more additives selected from the group consisting of organic acids, glycerol, and zinc chloride.

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