Highly water-absorbent resin composition and method for producing the same

Abstract

The present invention relates to a superabsorbent polymer composition and a method for producing the same, and more particularly to a superabsorbent polymer composition having deodorizing properties and a method for producing the same.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0073035 filed June 7, 2023 and Korean Patent Application No. 10-2024-0073975 filed June 5, 2024, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a superabsorbent polymer composition and a method for producing the same, and more particularly to a superabsorbent polymer composition having deodorizing properties and a method for producing the same. [Background technology]

[0003] Super absorbent polymer (SAP) is a synthetic polymer capable of absorbing 500 to 1,000 times its own weight in water, and different developers have given it different names, such as SAM (Super Absorbency Material) or AGM (Absorbent Gel Material). These super absorbent polymers first came into practical use as sanitary products, and are now widely used in sanitary products such as baby diapers, as well as in soil water retention materials for gardening, water-stopping materials for civil engineering and construction, seedling sheets, freshness-preserving agents in the food distribution industry, and as compresses.

[0004] In most cases, such superabsorbent polymers are widely used in the field of sanitary materials, such as diapers and sanitary napkins. In such sanitary materials, the superabsorbent polymer is generally contained in a dispersed state within the pulp. However, in recent years, efforts have been made to provide thinner sanitary materials, such as diapers. As part of these efforts, the development of so-called pulpless diapers, which contain less pulp or even no pulp at all, has been actively pursued.

[0005] In the case of sanitary materials with a reduced pulp content or no pulp, the superabsorbent polymer is contained at a relatively high ratio, and such superabsorbent polymer particles are inevitably contained in multiple layers within the sanitary material. In order for the superabsorbent polymer particles contained in multiple layers to efficiently absorb liquids such as urine, the superabsorbent polymer must have a high water absorption capacity and water absorption rate. In addition, the absorbed liquid must not leak even under external pressure, and the superabsorbent polymer must also have permeability to maintain its original shape even when swollen due to the absorption of liquid.

[0006] Therefore, much research has been conducted into improving the basic water absorption and water retention of superabsorbent resins, such as by surface cross-linking.

[0007] However, superabsorbent polymers can be used in sanitary materials, and in this case, there is a problem of poor usability due to the foul odor of absorbed liquids such as human and pet excrement. In particular, it is necessary to suppress all of the foul odors originally contained in the absorbed liquid and the odors that arise during the use of sanitary materials containing superabsorbent polymers.

[0008] Therefore, although deodorizing substances have been conventionally mixed with highly water-absorbent resins, there have been problems such as the mixing of an excessive amount of deodorizing substance in order to effectively suppress odors, resulting in a decrease in water absorption capacity, or the inability to achieve the desired level of deodorizing ability based solely on antibacterial properties.

[0009] Therefore, there is a gradually increasing demand for not only the basic properties of superabsorbent resins, namely water absorption and water retention, but also odor suppression, and therefore there is a need to produce superabsorbent resins with excellent deodorizing properties. Summary of the Invention [Problem to be solved by the invention]

[0010] An object of the present invention is to provide a highly water-absorbent polymer composition having deodorizing properties and a method for producing the same.

[0011] More specifically, an object of the present invention is to provide a superabsorbent polymer composition and a method for producing the same, which minimizes the deterioration of the physical properties of the superabsorbent polymer by controlling the combination of deodorizing substances and has excellent deodorizing power. [Means for solving the problem]

[0012] In order to solve the above problems, the present invention provides the following superabsorbent polymer composition.

[0013] a superabsorbent resin comprising a base resin containing a crosslinked polymer obtained by crosslinking an acrylic acid-based monomer having at least a partially neutralized acidic group with an internal crosslinking agent, and a surface crosslinked layer formed on the surface of the base resin and obtained by additional crosslinking of the crosslinked polymer via a surface crosslinking agent; and Contains tannic acid; iodine compounds; and chelating agents.

[0014] The present invention also provides the following method for producing a superabsorbent polymer composition.

[0015] Step 1: cross-linking and polymerizing an acrylic acid monomer having at least a partially neutralized acid group in the presence of an internal cross-linking agent and a polymerization initiator to form a hydrogel polymer; a step (step 2) of preparing a base resin containing a crosslinked polymer by coarsely pulverizing, drying, and pulverizing the hydrogel polymer; Step 3: mixing the base resin with a surface cross-linking agent to prepare a mixture; and Step 4: heat-treating the mixture to prepare a superabsorbent resin having a surface cross-linked layer formed on the surface of the base resin; Tannic acid and an iodine compound are mixed with the superabsorbent resin having a surface cross-linked layer formed in step 4, and a chelating agent is mixed in the coarse grinding step in step 2 or mixed with the superabsorbent resin having a surface cross-linked layer formed in step 4. [Effects of the Invention]

[0016] As described above, the present invention is characterized by providing a superabsorbent polymer composition having excellent deodorizing power by combining a deodorizing substance with the superabsorbent polymer, and a method for producing the same.

[0017] Specifically, the present invention is characterized by providing a superabsorbent polymer composition capable of eliminating all of the malodors that initially occur due to urine discharged from the human body, as well as the malodors that occur due to bacteria on the skin during use of sanitary products or when used sanitary products are left unused, and a method for producing the same. DETAILED DESCRIPTION OF THE INVENTION

[0018] The terms used in this specification are merely used to describe exemplary embodiments and are not intended to limit the present invention. The singular expressions include the plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprise," "include," "comprise," "have," and the like are intended to specify the presence of embodied features, steps, components, or combinations thereof, and should be understood as not precluding the presence or additional possibility of one or more other features, steps, components, or combinations thereof.

[0019] The present invention can be modified in various ways and can have various forms, and the following detailed description will be given by way of example of specific embodiments, but it should be understood that this is not intended to limit the present invention to the specific disclosed embodiments, and that the present invention includes all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0020] Hereinafter, the superabsorbent polymer composition and the method for producing the same will be described in more detail with reference to specific embodiments of the invention.

[0021] Prior to this, the terminology used herein is for the purpose of referring to particular embodiments only and is not intended to limit the present invention, and the singular forms used herein also include the plural forms unless the context clearly dictates otherwise.

[0022] For reference, in this specification, the term "superabsorbent polymer" may refer to the superabsorbent polymer polymer itself depending on the context, or may be used to encompass all polymers that have been subjected to additional processes such as surface crosslinking, fine powder regranulation, drying, pulverization, classification, etc. to be made into a state suitable for commercialization.

[0023] In addition, in the present specification, the term "base resin" or "base resin powder" refers to a polymer prepared in the form of particles or powder by drying and pulverizing a polymer obtained by polymerizing an acrylic acid-based monomer, and which has not yet been subjected to the surface modification or surface crosslinking steps described below.

[0024] (Super absorbent resin composition) According to one embodiment of the present invention, a superabsorbent polymer composition is provided.

[0025] The superabsorbent polymer composition includes a base resin including a crosslinked polymer obtained by crosslinking an acrylic acid-based monomer having at least a partially neutralized acidic group with an internal crosslinking agent, and a surface crosslinked layer formed on the surface of the base resin and obtained by additional crosslinking of the crosslinked polymer via a surface crosslinking agent; and tannic acid; an iodine compound; and a chelating agent.

[0026] The acrylic acid-based monomer may be any monomer commonly used in the manufacture of superabsorbent resins. Specifically, the acrylic acid-based monomer may be a compound represented by the following Chemical Formula 1:

[0027] [Chemical formula 1] R 1 -COOM 1

[0028] In the above Chemical Formula 1, R 1 is an alkyl group having 2 to 5 carbon atoms and containing an unsaturated bond, M 1 is a hydrogen atom, a monovalent or divalent metal, an ammonium group, or an organic amine salt.

[0029] Preferably, the acrylic acid monomer includes at least one selected from the group consisting of acrylic acid, methacrylic acid, and their monovalent metal salts, divalent metal salts, ammonium salts, and organic amine salts.

[0030] The acrylic acid-based monomer may have an acidic group, and at least a portion of the acidic group may be neutralized. Preferably, the monomer may be partially neutralized with an alkaline substance such as sodium hydroxide, potassium hydroxide, or ammonium hydroxide.

[0031] In this case, the degree of neutralization of the monomer may be 40 to 95 mol%, 40 to 80 mol%, or 45 to 75 mol%. The range of the degree of neutralization may vary depending on the final properties, but if the degree of neutralization is too high, the neutralized monomer may precipitate, making it difficult to carry out polymerization smoothly. Conversely, if the degree of neutralization is too low, the water absorption capacity of the polymer may be significantly reduced and it may exhibit properties similar to elastic rubber, which makes it difficult to handle.

[0032] Meanwhile, the polymerization of the acrylic acid monomer is carried out in the presence of a crosslinking agent ("internal crosslinking agent") to improve the physical properties of the resin. The crosslinking agent is used to internally crosslink the hydrogel polymer and can be used separately from the "surface crosslinking agent" described below.

[0033] As the internal cross-linking agent, any compound can be used as long as it enables the introduction of cross-linking bonds during polymerization of the acrylic acid-based monomer. Non-limiting examples of the internal crosslinking agent include 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, glycerin tri(meth)acrylate, pentaerythritol tetraacrylate, triallylamine, allyl (meth)acrylate, ethylene glycol diglycidyl ether, propylene glycol, and ethylene carbonate. These crosslinking agents may be used alone or in combination.

[0034] The internal crosslinking agent may be added at a concentration of 0.001 to 1 wt %, 0.01 to 0.8 wt %, or 0.1 to 0.7 wt % relative to the monomer composition. In other words, if the concentration of the internal crosslinking agent is too low, the water absorption rate of the resin may decrease and the gel strength may weaken, which is undesirable. Conversely, if the concentration of the internal crosslinking agent is too high, the water absorption capacity of the resin may decrease, making it unsuitable for use as a water absorbent.

[0035] In addition, the base resin may further contain additives such as a thickener, a plasticizer, a storage stabilizer, and an antioxidant, if necessary.

[0036] The surface cross-linked layer is formed by additionally cross-linking a cross-linked polymer using a surface cross-linking agent as a medium. In this case, the surface cross-linking agent is not particularly limited as long as it is a surface cross-linking agent generally used for surface cross-linking of a superabsorbent resin and is a compound capable of reacting with a functional group of the polymer.

[0037] Preferably, in order to improve the properties of the resulting superabsorbent resin, one or more compounds selected from the group consisting of polyhydric alcohol compounds; epoxy compounds; polyamine compounds; haloepoxy compounds; condensation products of haloepoxy compounds; oxazoline compounds; mono-, di-, or polyoxazolidinone compounds; cyclic urea compounds; polyvalent metal salts; and alkylene carbonate compounds can be used as the surface crosslinking agent.

[0038] Specifically, examples of polyhydric alcohol compounds that can be used include one or more selected from the group consisting of 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.

[0039] In addition, as the epoxy compound, ethylene glycol diglycidyl ether, glycidol, etc. can be used, and as the polyamine compound, one or more compounds selected from the group consisting of ethylenediamine, diethylenetriamine, triethylenetetraamine, tetraethylenepentamine, pentaethylenehexamine, polyethyleneimine, and polyamidepolyamine can be used.

[0040] The haloepoxy compound may be epichlorohydrin, epibromohydrin, or α-methylepichlorohydrin, while the mono-, di-, or polyoxazolidinone compound may be, for example, 2-oxazolidinone.

[0041] The alkylene carbonate compound may be ethylene carbonate. These may be used alone or in combination. On the other hand, in order to increase the efficiency of the surface cross-linking step, one or more polyhydric alcohol compounds having 2 to 10 carbon atoms may be used as the surface cross-linking agent.

[0042] The content of the surface crosslinking agent to be added can be appropriately selected depending on the specific type of the surface crosslinking agent to be added and the reaction conditions, and usually, about 0.001 to about 5 parts by weight, preferably about 0.01 to about 3 parts by weight, more preferably about 0.05 to about 2 parts by weight, can be used relative to 100 parts by weight of the polymer.

[0043] If the content of the surface cross-linking agent is too small, the surface cross-linking reaction hardly occurs, and if it exceeds 5 parts by weight per 100 parts by weight of the polymer, the surface cross-linking reaction may proceed excessively, resulting in a decrease in water absorption capacity and physical properties.

[0044] Meanwhile, the surface cross-linking agent may further contain an inorganic substance. The inorganic substance may be one or more inorganic substances selected from the group consisting of silica, clay, alumina, silica-alumina composites, titania, zinc oxide, and aluminum sulfate. The inorganic substance may be used in powder or liquid form, particularly alumina powder, silica-alumina powder, titania powder, or nanosilica solution. The inorganic substance may be used in an amount of about 0.001 to about 1 part by weight per 100 parts by weight of the base resin.

[0045] The superabsorbent polymer composition according to one embodiment of the present invention may contain, as deodorizing substances, tannic acid, an iodine compound, and a chelating agent. When the superabsorbent polymer composition containing tannic acid, an iodine compound, and a chelating agent is applied to a hygiene product, it has the effect of eliminating the basic odor of a liquid absorbed in the hygiene product and the effect of eliminating additional odors that may be generated due to bacterial growth during use.

[0046] Tannic acid is a type of polyphenol found in fruit peels, vegetables, cacao, nuts, etc. Tannic acid has an intramolecular hydroxyl group (-OH), which forms a hydrogen bond with the oxygen (O) or nitrogen (N) atom of compounds that cause malodor, allowing tannic acid to capture malodorous substances and reduce the odor.

[0047] The iodine compound may be an iodine solution (I2) or a metal iodide salt. The iodine solution is a solution of I2 dissolved in water, and the metal iodide salt may be a solution of I2 and at least one selected from the group consisting of CuI, NaI, and KI dissolved in water, or may be added in the form of a powder obtained by drying an aqueous solution during the manufacturing process. Iodine compounds, like tannic acid or chelating agents, can also be added to superabsorbent resins to impart deodorizing properties. Iodine compounds oxidize malodorous substances to remove odors, and are generally effective as they act on most malodorous substances.

[0048] The superabsorbent polymer composition according to one embodiment of the present invention may contain a chelating agent. In the case of a hygiene product containing a superabsorbent polymer composition, bacteria originating from the skin may come into contact with the absorbed liquid, causing the bacteria to grow and resulting in additional odors. The chelating agent can inhibit the growth of such bacteria.

[0049] The chelating agent may include an aminoacetate-based chelating agent. Specifically, the aminoacetate-based chelating agent may include one or more selected from the group consisting of ethylenediaminetetraacetic acid (EDTA), L-glutamic acid diacetic acid (GLDA), methylglycine diacetic acid (MGDA), hydroxyethylethylenediaminetriacetic acid (HEDTA), ethanoldiglycine acid (EDG), diethylenetriaminepentaacetic acid (DTPA), and salts thereof. More specifically, the chelating agent may be ethylenediaminetetraacetic acid (EDTA) or L-glutamic acid diacetic acid (GLDA).

[0050] The tannic acid may be contained in an amount of more than 0.001 to 0.5 parts by weight based on the solid content per 100 parts by weight of the base resin, specifically, more than 0.001 part by weight, 0.002 parts by weight or more, 0.003 parts by weight or more, 0.005 parts by weight or more, 0.01 parts by weight or more, 0.015 parts by weight or more, or 0.02 parts by weight or more to 0.5 parts by weight or less, 0.3 parts by weight or less, 0.1 parts by weight or less, 0.07 parts by weight or less, 0.05 parts by weight or less, 0.04 parts by weight or less, or 0.03 parts by weight or less.

[0051] Only when the content of tannic acid satisfies the above range can the deodorizing power be maximized while minimizing the deterioration of the physical properties of the superabsorbent resin.

[0052] The iodine compound may be included in an amount of 0.01 to 1.0 part by weight per 100 parts by weight of the base resin, specifically, 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 to 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.

[0053] When the content of the iodine compound satisfies the above range, the deterioration of the physical properties of the superabsorbent resin is minimal, and the deodorizing power can be maximized.

[0054] The chelating agent may be included in an amount of 0.05 to 4.0 parts by weight based on the solid content per 100 parts by weight of the base resin. Specifically, the chelating agent may be included in an amount of 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 to 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, based on the solid content per 100 parts by weight of the base resin.

[0055] It is preferable that the chelating agent be included within the above content range in order to minimize the degree of deterioration in deodorizing ability and properties due to the level of bacterial growth inhibition sought in the present invention while maintaining the inherent water absorption properties of the superabsorbent polymer.

[0056] The superabsorbent polymer composition may further contain additional additives in addition to tannic acid, an iodine compound, and a chelating agent.

[0057] The additional additives may further include one or more additives selected from the group consisting of organic acids, glycerin, and zinc chloride.

[0058] 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. Specifically, the organic acid may be citric acid or glycine.

[0059] Organic acids, like tannic acid, can exhibit deodorizing effects in highly absorbent resins. Organic acids also have the effect of neutralizing the ammonia dissolved in urine. Glycine, in particular, can capture malodorous substances by chemically reacting with them. Malodorous substances generally have small molecular weights, and when they react with glycine, the odor is reduced or eliminated, effectively eliminating the odor. Glycine is particularly effective in reducing the odor of aldehyde and ketone compounds.

[0060] Glycerin generally dissolves a variety of deodorizing substances and helps them exert their deodorizing power.

[0061] Zinc chloride generally has antibacterial properties, acting as an antiseptic and preservative that inhibits bacterial metabolism.

[0062] The tannic acid and iodine compound may be included separately from the superabsorbent resin. As described in the manufacturing method below, the tannic acid and iodine compound are mixed with the superabsorbent resin after forming a surface cross-linked layer on the surface of the base resin. Therefore, the tannic acid and iodine compound may be present mainly outside the superabsorbent resin particles.

[0063] The chelating agent may be contained within the base resin or separately from the superabsorbent resin. As described in the manufacturing method below, the chelating agent is mixed in the coarse grinding step (Step 2) or mixed into the superabsorbent resin after forming a surface cross-linked layer on the surface of the base resin. In particular, when the chelating agent is mixed in the coarse grinding step (Step 2), the chelating agent may be impregnated into the base resin.

[0064] (Method of producing superabsorbent resin composition) According to one embodiment of the present invention, there is provided a method for producing a superabsorbent polymer composition.

[0065] The method for producing the superabsorbent polymer composition includes: The method includes the steps of: (Step 1) cross-linking an acrylic acid monomer having at least a partially neutralized acid group in the presence of an internal cross-linking agent and a polymerization initiator to form a hydrogel polymer; (Step 2) roughly pulverizing the hydrogel polymer, and then pulverizing and drying the cross-linked polymer to prepare a base resin containing the cross-linked polymer; (Step 3) mixing a surface cross-linking agent into the base resin to prepare a mixture; and (Step 4) heat-treating the mixture to prepare a superabsorbent resin having a surface cross-linked layer formed on the surface of the base resin. Tannic acid and an iodine compound can be mixed with the superabsorbent resin having a surface cross-linked layer formed in step 4, and a chelating agent can be mixed in the coarse grinding step in step 2 or mixed with the superabsorbent resin having a surface cross-linked layer formed in step 4.

[0066] The method for producing superabsorbent polymers generally involves polymerizing acrylic acid monomers to produce a hydrogel polymer and then pulverizing the polymer. To improve various properties of the superabsorbent polymers, the surface of the produced superabsorbent polymers is crosslinked.

[0067] The present invention aims to provide a superabsorbent polymer composition having deodorizing properties by mixing the surface-crosslinked superabsorbent polymer with tannic acid, an iodine compound, and a chelating agent.

[0068] The present invention will be described in detail below for each step.

[0069] (Stage 1) Step 1 is a step of preparing a hydrogel polymer, specifically, a step of cross-linking a monomer composition including an acrylic acid-based monomer having at least a partially neutralized acid group to form a hydrogel polymer.

[0070] The acrylic acid-based monomer may be any monomer commonly used in the manufacture of superabsorbent resins. Specifically, the acrylic acid-based monomer may be a compound represented by the following Chemical Formula 1:

[0071] [Chemical formula 1] R 1 -COOM 1

[0072] In the above Chemical Formula 1, R 1 is an alkyl group having 2 to 5 carbon atoms and containing an unsaturated bond, M 1 is a hydrogen atom, a monovalent or divalent metal, an ammonium group, or an organic amine salt.

[0073] Preferably, the acrylic acid monomer includes at least one selected from the group consisting of acrylic acid, methacrylic acid, and their monovalent metal salts, divalent metal salts, ammonium salts, and organic amine salts.

[0074] The acrylic acid-based monomer may have an acidic group, and at least a portion of the acidic group may be neutralized. Preferably, the monomer may be partially neutralized with an alkaline substance such as sodium hydroxide, potassium hydroxide, or ammonium hydroxide.

[0075] In this case, the degree of neutralization of the monomer may be 40 to 95 mol%, or 40 to 80 mol%, or 45 to 75 mol%. The range of the degree of neutralization may vary depending on the final properties, but if the degree of neutralization is too high, the neutralized monomer may precipitate, making it difficult to carry out polymerization smoothly. Conversely, if the degree of neutralization is too low, the water absorption capacity of the polymer may be significantly reduced and it may exhibit properties similar to elastic rubber, which makes it difficult to handle.

[0076] The monomer composition may contain a polymerization initiator that is commonly used in the production of superabsorbent resins.

[0077] The polymerization initiator may be a thermal polymerization initiator or a photopolymerization initiator depending on the polymerization method, but even in the case of a photopolymerization method, a certain amount of heat is generated by UV irradiation, etc., and also by the progress of the polymerization reaction, which is an exothermic reaction, so a thermal polymerization initiator may be additionally used.

[0078] The photopolymerization initiator may be one or more compounds selected from the group consisting of benzoin ether, dialkyl acetophenone, hydroxyl alkyl ketone, phenyl glyoxylate, benzyl dimethyl ketal, acyl phosphine, and α-aminoketone. A specific example of the acyl phosphine is commercially available lucirin TPO, i.e., 2,4,6-trimethyl-benzoyl-diphenyl phosphine oxide. For more information on various photopolymerization initiators, see page 115 of Reinhold Schwalm's book "UV Coatings: Basics, Recent Developments and New Applications" (Elsevier, 2007).

[0079] The thermal polymerization initiator may be one or more compounds selected from the group consisting of persulfate initiators, azo initiators, hydrogen peroxide, and ascorbic acid. Specific examples of persulfate initiators include sodium persulfate (NaSO), potassium persulfate (KSO), and ammonium persulfate ((NHSO). Furthermore, examples of azo initiators include 2,2-azobis(2-amidinopropane) dihydrochloride, 2,2-azobis-(N,N-dimethylene)isobutyramidine dihydrochloride, 2-(carbamoylazo)isobutylonitrile, 2,2-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride, and 4,4-azobis-(4-cyanovaleric acid). Examples of thermal polymerization initiators include methyl methyl acrylate, methyl meth ...

[0080] Such a polymerization initiator may be added at a concentration of 0.001 to 1 wt % or 0.005 to 0.1 wt % relative to the monomer composition. In other words, if the concentration of the polymerization initiator is too low, the polymerization rate may slow down and a large amount of residual monomer may be extracted into the final product, which is undesirable. Conversely, if the concentration of the polymerization initiator is too high, the polymer chains forming the network may become shorter, resulting in a higher content of water-soluble components and a decrease in the physical properties of the resin, such as a decrease in water absorption capacity under pressure, which is undesirable.

[0081] 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 resin obtained by the polymerization of the acrylic acid-based monomer. The crosslinking agent is used to internally crosslink the hydrogel polymer and can be used separately from the "surface crosslinking agent" described below.

[0082] As the internal cross-linking agent, any compound can be used as long as it enables the introduction of cross-linking bonds during polymerization of the acrylic acid monomer. Non-limiting examples of the internal crosslinking agent include 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, glycerin tri(meth)acrylate, pentaerythritol tetraacrylate, triallylamine, allyl (meth)acrylate, ethylene glycol diglycidyl ether, propylene glycol, and ethylene carbonate. These crosslinking agents may be used alone or in combination.

[0083] The internal crosslinking agent may be added at a concentration of 0.001 to 1 wt %, 0.01 to 0.8 wt %, or 0.1 to 0.7 wt % relative to the monomer composition. In other words, if the concentration of the internal crosslinking agent is too low, the water absorption rate of the resin may decrease and the gel strength may weaken, which is undesirable. Conversely, if the concentration of the internal crosslinking agent is too high, the water absorption capacity of the resin may decrease, making it unsuitable for use as a water absorbent.

[0084] In addition, the monomer composition may further contain additives such as a thickener, a plasticizer, a storage stabilizer, and an antioxidant, if necessary.

[0085] The monomer composition may be prepared in the form of a solution in which raw materials such as the acrylic acid-based monomer, polymerization initiator, internal crosslinking agent, and foaming agent are dissolved in a solvent.

[0086] In this case, any solvent that can dissolve the raw materials described above can be used without limitation on its composition, such as 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.

[0087] The formation of the hydrogel polymer through polymerization of the monomer composition can be carried out by a conventional polymerization method, and the process is not particularly limited.

[0088] As a non-limiting example, the polymerization method can be broadly divided into thermal polymerization and photopolymerization depending on the type of polymerization energy source. Thermal polymerization can be carried out in a reactor having a stirring shaft such as a kneader, and photopolymerization can be carried out in a reactor equipped with a movable conveyor belt.

[0089] For example, the monomer composition can be introduced into a reactor such as a kneader equipped with a stirring shaft, and then thermally polymerized by supplying hot air or heating the reactor to obtain a hydrogel polymer. Depending on the type of stirring shaft installed in the reactor, the hydrogel polymer discharged from the reactor outlet can be obtained as particles ranging from several millimeters to several centimeters in size. Specifically, the hydrogel polymer obtained can be obtained in various forms depending on the concentration and injection rate of the monomer composition injected, but typically has a (weight-average) particle size of 2 to 50 mm.

[0090] As another example, when the monomer composition is photopolymerized in a reactor equipped with a movable conveyor belt, a sheet-shaped hydrogel polymer can be obtained. The thickness of the sheet can vary depending on the concentration and injection rate of the monomer composition, but is preferably adjusted to a thickness of 0.5 to 10 cm to ensure uniform polymerization throughout the sheet while maintaining a stable production rate.

[0091] The hydrogel polymer formed in this manner may exhibit a water content of 40 to 80% by weight. Here, the water content is the weight of water in the total weight of the hydrogel polymer, which may be calculated by subtracting the weight of the polymer in a dry state from the weight of the hydrogel polymer. Specifically, it may be defined as the value calculated by measuring the weight loss due to evaporation of water in the polymer during the drying process by increasing the temperature of the polymer using infrared heating. The drying conditions are to increase the temperature from room temperature to approximately 180°C and then maintain it at 180°C, and the total drying time may be set to 20 minutes, including a 5-minute temperature increase step.

[0092] In step 1, the hydrogel polymer may be produced in sheet form.

[0093] (Stage 2) Step 2 of the present invention is a step in which the sheet-shaped hydrogel polymer produced in the previous step 1 is coarsely crushed, dried, crushed and classified to form a base resin powder.

[0094] Specifically, in order to not only increase the drying efficiency of the hydrogel polymer but also affect the morphology of the superabsorbent polymer, thereby influencing various physical properties of the superabsorbent polymer, including its absorption rate, and particularly to improve the water absorption rate of the superabsorbent polymer, the present invention may further include a step of coarsely pulverizing the hydrogel polymer before drying. Hereinafter, for convenience, the term "coarse pulverization" will be used herein to refer to pulverization before drying, to distinguish it from pulverization after drying.

[0095] The pulverizer used for the coarse pulverization is not limited in configuration, and specifically may include any one selected from the group of pulverizing equipment consisting of a vertical pulverizer, a turbo cutter, a turbo grinder, a rotary cutter mill, a cutter mill, a disc mill, a shred crusher, a crusher, a chopper, and a disc cutter, but is not limited to the above examples. Specifically, a chopper may be used for the coarse pulverization of the present invention.

[0096] In this case, the coarse pulverization step can be performed to pulverize the hydrogel polymer to a particle size of about 2 mm to about 20 mm. Pulverization to a particle size of less than 2 mm is technically difficult due to the high water content of the hydrogel polymer, and the pulverized particles may aggregate together. On the other hand, pulverization to a particle size of more than 20 mm can result in little increase in the efficiency of the subsequent drying step. Specifically, the coarse pulverization step can be performed using a chopper with holes of 15 to 17 mm.

[0097] In addition, a chelating agent can be mixed with the hydrogel polymer in the coarse grinding step. Specifically, the sheet-shaped hydrogel polymer prepared in step 1 is cut into thin strips, and the chelating agent can be sprayed onto the hydrogel polymer while chopping.

[0098] The chelating agent may be mixed in the form of an aqueous solution or a powder.

[0099] The chelating agent may include an aminoacetate-based chelating agent.

[0100] The aminoacetate chelating agent may include one or more selected from the group consisting of ethylenediaminetetraacetic acid (EDTA), L-glutamic acid diacetic acid (GLDA), methylglycine diacetic acid (MGDA), hydroxyethylethylenediaminetriacetic acid (HEDTA), ethanoldiglycine acid (EDG), diethylenetriaminepentaacetic acid (DTPA), and salts thereof.

[0101] The chelating agent may be included in an amount of 0.05 to 4.0 parts by weight based on the solid content per 100 parts by weight of the base resin. Specifically, the chelating agent may be mixed in an amount of 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 to 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, based on 100 parts by weight of the base resin.

[0102] It is preferable that the chelating agent be included within the above content range in order to maintain the inherent water absorption properties of the superabsorbent polymer while suppressing bacterial growth at the level desired by the present invention and minimizing the degree of deterioration in properties due to the addition of the chelating agent.

[0103] The drying can be carried out at a temperature of 120 to 250°C, 140 to 200°C, or 150 to 190°C. The drying temperature can be defined as the temperature of the heat medium supplied for drying or the temperature inside the drying reactor containing the heat medium and polymer during the drying process. A low drying temperature and a long drying time can reduce process efficiency. To prevent this, the drying temperature is preferably 120°C or higher. Furthermore, if the drying temperature is higher than necessary, the surface of the hydrogel polymer can be overdried, resulting in increased generation of fine powder in the subsequent pulverization step and reduced physical properties of the final resin. To prevent this, the drying temperature is preferably 250°C or lower.

[0104] At this time, the drying time in the drying step is not particularly limited, but may be adjusted to 20 to 90 minutes at the drying temperature in consideration of process efficiency and the physical properties of the resin.

[0105] The drying can be carried out using a common medium, for example, by supplying hot air to the pulverized hydrogel polymer, irradiating it with infrared rays, microwave irradiation, or ultraviolet rays.

[0106] It is preferable that this drying be carried out so that the dried polymer has a moisture content of 0.1 to 10 wt%. That is, if the moisture content of the dried polymer is less than 0.1 wt%, excessive drying can increase production costs and cause degradation of the crosslinked polymer, which is undesirable. If the moisture content of the dried polymer exceeds 10 wt%, defects can occur in subsequent processes, which is undesirable.

[0107] Next, the dried hydrogel polymer can be pulverized. This is a step for optimizing the surface area of ​​the base resin powder and the superabsorbent resin. The pulverization can be performed so that the particle size of the pulverized polymer is 150 to 850 μm.

[0108] In this case, the grinding machine that can be used may be a conventional one such as a pin mill, a hammer mill, a screw mill, a roll mill, a disc mill, or a jog mill.

[0109] In addition, in order to control the physical properties of the superabsorbent resin to be manufactured as a final product, a step of selectively classifying particles having a particle size of 150 to 850 μm is carried out from the polymer particles obtained through the pulverization step.

[0110] The base resin powder can be obtained through the above classification steps. Such base resin powder can have a particle size of 150 to 850 μm and can contain 2% by weight or less, or 1% by weight or less, of fine powder having a particle size of less than 150 μm.

[0111] (Stage 3) Step 3 of the present invention is a step of mixing a surface cross-linking agent with the base resin powder prepared in step 2.

[0112] The surface cross-linking agent used in step 3 includes a surface cross-linking liquid, and the surface cross-linking agent is not particularly limited as long as it is a surface cross-linking agent generally used for surface cross-linking of a superabsorbent resin and is a compound capable of reacting with a functional group of the polymer.

[0113] Preferably, in order to improve the properties of the resulting superabsorbent resin, one or more compounds selected from the group consisting of polyhydric alcohol compounds; epoxy compounds; polyamine compounds; haloepoxy compounds; condensation products of haloepoxy compounds; oxazoline compounds; mono-, di-, or polyoxazolidinone compounds; cyclic urea compounds; polyvalent metal salts; and alkylene carbonate compounds can be used as the surface crosslinking agent.

[0114] Specifically, examples of polyhydric alcohol compounds that can be used include one or more selected from the group consisting of 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.

[0115] In addition, as the epoxy compound, ethylene glycol diglycidyl ether, glycidol, etc. can be used, and as the polyamine compound, one or more compounds selected from the group consisting of ethylenediamine, diethylenetriamine, triethylenetetraamine, tetraethylenepentamine, pentaethylenehexamine, polyethyleneimine, and polyamidepolyamine can be used.

[0116] The haloepoxy compound may be epichlorohydrin, epibromohydrin, or α-methylepichlorohydrin, while the mono-, di-, or polyoxazolidinone compound may be, for example, 2-oxazolidinone.

[0117] The alkylene carbonate compound may be ethylene carbonate. These may be used alone or in combination. On the other hand, in order to increase the efficiency of the surface cross-linking step, one or more polyhydric alcohol compounds having 2 to 10 carbon atoms may be used as the surface cross-linking agent.

[0118] The content of the surface crosslinking agent to be added can be appropriately selected depending on the type of the surface crosslinking agent to be added and the reaction conditions, and usually, about 0.001 to about 5 parts by weight, preferably about 0.01 to about 3 parts by weight, more preferably about 0.05 to about 2 parts by weight, can be used relative to 100 parts by weight of the polymer.

[0119] If the content of the surface cross-linking agent is too small, the surface cross-linking reaction hardly occurs, and if it exceeds 5 parts by weight per 100 parts by weight of the polymer, the surface cross-linking reaction may proceed excessively, resulting in a decrease in water absorption capacity and physical properties.

[0120] Meanwhile, the surface cross-linking agent may also be used in the step of forming a surface cross-linked layer by adding an inorganic substance. Such inorganic substances may be one or more inorganic substances selected from the group consisting of silica, clay, alumina, silica-alumina composites, titania, zinc oxide, and aluminum sulfate. The inorganic substance may be used in powder or liquid form, particularly alumina powder, silica-alumina powder, titania powder, or nanosilica solution. The inorganic substance may be used in an amount of about 0.001 to about 1 part by weight per 100 parts by weight of the base resin.

[0121] Meanwhile, the method of mixing the surface cross-linking agent with the base resin is not particularly limited as long as it can be uniformly mixed with the base resin, and any method can be appropriately selected and used.

[0122] For example, a method in which the surface crosslinking agent and the base resin are placed in a reaction tank and mixed, a method in which the surface crosslinking agent is sprayed onto the base resin, a method in which the base resin and the surface crosslinking agent are continuously supplied to a continuously operated mixer and mixed, etc. can be used.

[0123] In this case, the surface crosslinking agent may be in the form of 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, the surface crosslinking agent is suitable for being uniformly dispersed in the base resin and, at the same time, aggregation of the base resin can be prevented.

[0124] (Stage 4) Step 4 is a step for further improving the physical properties of the superabsorbent resin by reacting the base resin with a surface cross-linking agent to form an interpenetrating polymer network on the surface of the cross-linked polymer contained in the base resin. Through this surface modification, a surface cross-linked layer is formed on the surface of the pulverized base resin particles.

[0125] The formation of the surface cross-linked layer can be carried out by a conventional method for increasing the cross-linking density on the surface of the polymer particles, for example, by mixing the pulverized polymer with a surface cross-linking agent containing a surface cross-linking agent, and heat-treating the mixture to cause a cross-linking reaction.

[0126] Step 4 can be performed at a temperature of about 80°C to about 250°C. More specifically, the surface cross-linking process can be performed at a temperature of about 100°C to about 220°C, or about 110°C to about 200°C, or 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 cross-linking reaction temperature is less than 160°C or the reaction time is too short, the surface cross-linking reaction may not proceed well, resulting in low permeability. If the temperature exceeds 200°C or the reaction time is too long, the water retention capacity may be reduced.

[0127] The temperature raising means for the surface crosslinking reaction is not particularly limited. Heating can be achieved by supplying a heat medium or directly supplying a heat source. At this time, the type of heat medium that can be used may be a heated fluid such as steam, hot air, or hot oil, but the present invention is not limited thereto. The temperature of the heat medium to be supplied may be appropriately selected in consideration of the heat medium means, the temperature raising rate, and the target temperature. Meanwhile, examples of a heat source that is directly supplied include electric heating and gas heating, but the present invention is not limited to the above-mentioned examples.

[0128] Furthermore, tannic acid, an iodine compound, and a chelating agent may be mixed with the superabsorbent resin having the surface cross-linked layer formed thereon. The tannic acid and the iodine compound chemically bond with volatile malodorous substances such as aldehydes, thereby imparting deodorizing power to the superabsorbent resin.

[0129] Tannic acid may be mixed in an amount of more than 0.001 to 0.5 parts by weight based on the solid content relative to 100 parts by weight of the base resin, specifically, more than 0.001 part by weight, 0.002 parts by weight or more, 0.003 parts by weight or more, 0.005 parts by weight or more, 0.01 parts by weight or more, 0.015 parts by weight or more, or 0.02 parts by weight or more to 0.5 parts by weight or less, 0.3 parts by weight or less, 0.1 parts by weight or less, 0.07 parts by weight or less, 0.05 parts by weight or less, 0.04 parts by weight or less, or 0.03 parts by weight or less.

[0130] The iodine compound may be mixed in an amount of 0.01 to 1.0 part by weight per 100 parts by weight of the base resin, specifically, 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 to 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.

[0131] In order to exhibit the deodorizing ability at the level sought in the present invention while maintaining the inherent water absorption properties of the superabsorbent polymer, it is preferable that the deodorizing substance, tannic acid or iodine compound, be contained within the above content range.

[0132] The deodorizing substance containing tannic acid and an iodine compound can be mixed in the form of an aqueous solution or powder with the base resin together with the surface crosslinking agent.

[0133] The type of chelating agent to be mixed, the amount to be mixed, and the form to be mixed are explained in step 1.

[0134] In addition, the superabsorbent resin having the surface cross-linked layer may further contain an additional additive, which may include one or more additives selected from the group consisting of organic acid, glycerin, and zinc chloride.

[0135] The organic acid may be at least one selected from the group consisting of citric acid, glycine, acetic acid, formic acid, fumaric acid, lactic acid, and propionic acid. Specifically, the organic acid may be citric acid or glycine. The organic acid may exhibit deodorizing effects in the superabsorbent resin, similar to a deodorizing substance.

[0136] The organic acid, glycerin, and zinc chloride may be mixed in the form of an aqueous solution using water as a solvent or in the form of powder.

[0137] When the deodorant substance and the chelating agent are added to the highly water-absorbent resin having the surface cross-linked layer formed thereon after hydration in the form of an aqueous solution, a drying step can be additionally carried out later.

[0138] Preferred examples are presented below to aid in understanding the invention, but the following examples are merely for illustrative purposes and are not intended to limit the scope of the invention.

[0139] The reagents used in the comparative examples and examples described below were obtained from the following sources.

[0140] EDTA aqueous solution: Daejung Chemicals and Metals Tannic acid aqueous solution: Samchun Chemical Iodine solution: Bookwang Tech Glycerin aqueous solution: Sigma-Aldrich Glycine aqueous solution: Sigma-Aldrich

[0141] Comparative Example 1 A monomer aqueous solution composition with a monomer concentration of 45.8 wt% was prepared by mixing 100 g of acrylic acid, 0.37 g of N,N'-methylenebisacrylamide as a crosslinker, 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. The monomer aqueous solution composition was then introduced into the feed section of a polymerization reactor equipped with a continuously moving conveyor belt, and irradiated with ultraviolet light (irradiation dose: 10 mW / cm) using a UV irradiation device while maintaining the polymerization atmosphere temperature at 80°C. 2 ) and UV polymerization was carried out for 2 minutes to produce a sheet-shaped hydrogel polymer.

[0142] The hydrogel polymer was chopped using a meat chopper with 16 mm holes. The water content of the chopped hydrogel polymer was 47 wt%. The hydrogel polymer was then dried in a hot air dryer at 185°C for 30 minutes, and the dried hydrogel polymer was pulverized using a pin mill pulverizer. The polymer was then classified using a sieve to produce a base resin having a particle size range of 150 μm to 850 μm.

[0143] Next, 100 parts by weight of the prepared base resin was uniformly mixed with a surface cross-linking 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)), and the mixture was subjected to a surface cross-linking reaction at 140°C for 30 minutes. After the surface treatment was completed, a superabsorbent resin with a particle size range of 150 to 850 μm was obtained using a sieve.

[0144] Example 1 A monomer aqueous solution composition with a monomer concentration of 45.8 wt% was prepared by mixing 100 g of acrylic acid, 0.37 g of N,N'-methylenebisacrylamide as a crosslinker, 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. The monomer aqueous solution composition was then introduced into the feed section of a polymerization reactor equipped with a continuously moving conveyor belt, and irradiated with ultraviolet light (irradiation dose: 10 mW / cm) using a UV irradiation device while maintaining the polymerization atmosphere temperature at 80°C. 2 ) and UV polymerization was carried out for 2 minutes to produce a sheet-shaped hydrogel polymer.

[0145] The hydrogel polymer was chopped using a meat chopper with 16 mm holes. The water content of the chopped hydrogel polymer was 47 wt%. The hydrogel polymer was then dried in a hot air dryer at 185°C for 30 minutes, and the dried hydrogel polymer was pulverized using a pin mill pulverizer. The polymer was then classified using a sieve to produce a base resin having a particle size range of 150 μm to 850 μm.

[0146] Next, 100 parts by weight of the prepared base resin was uniformly mixed with a surface cross-linking 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)), and the mixture was subjected to a surface cross-linking reaction at 140°C for 30 minutes. After the surface treatment was completed, a superabsorbent resin with a particle size range of 150 to 850 μm was obtained using a sieve.

[0147] The surface-treated superabsorbent resin was mixed with EDTA, tannic acid, iodine solution, and glycerin in aqueous solution. The EDTA aqueous solution used had a concentration of 40%. The tannic acid aqueous solution used had a concentration of 5 parts by weight of tannic acid solids based on 100 parts by weight of the aqueous solution. The iodine solution (liquid I2) used had a concentration of 0.1%.

[0148] EDTA was mixed at 0.5 parts by weight of solid content per 100 parts by weight of base resin, tannic acid was mixed at 0.015 parts by weight of solid content per 100 parts by weight of base resin, and iodine solution was mixed at 0.1 parts by weight per 100 parts by weight of base resin. Then, a drying step was carried out at 80°C for 25 minutes.

[0149] Example 2 A surface-treated superabsorbent resin was produced in the same manner as in Example 1.

[0150] The surface-treated superabsorbent resin was mixed with EDTA, tannic acid, and iodine solution in aqueous solution form. The EDTA aqueous solution used had a solids concentration of 40%. The tannic acid aqueous solution used had a tannic acid solids concentration of 5 parts by weight based on 100 parts by weight of the aqueous solution. The iodine solution (liquid I2) used had a concentration of 0.1%.

[0151] EDTA was mixed at 0.5 parts by weight of solid content per 100 parts by weight of base resin, tannic acid was mixed at 0.05 parts by weight of solid content per 100 parts by weight of base resin, and iodine solution was mixed at 0.1 parts by weight per 100 parts by weight of base resin. Then, a drying step was carried out at 80°C for 25 minutes.

[0152] Example 3 A surface-treated superabsorbent resin was produced in the same manner as in Example 1.

[0153] The surface-treated superabsorbent resin was mixed with EDTA, tannic acid, and iodine solution in aqueous solution form. The EDTA aqueous solution used had a solids concentration of 40%. The tannic acid aqueous solution used had a concentration of 5 parts by weight of tannic acid solids per 100 parts by weight of aqueous solution. The iodine solution (liquid I2) used had a concentration of 0.1%.

[0154] EDTA was mixed at 0.5 parts by weight of solid content per 100 parts by weight of base resin, tannic acid was mixed at 0.1 parts by weight of solid content per 100 parts by weight of base resin, and iodine solution was mixed at 0.1 parts by weight per 100 parts by weight of base resin. Then, a drying step was carried out at 80°C for 25 minutes.

[0155] Example 4 A surface-treated superabsorbent resin was produced in the same manner as in Example 1.

[0156] The surface-treated superabsorbent resin was mixed with EDTA, tannic acid, and iodine solution in aqueous solution form. The EDTA aqueous solution used had a solids concentration of 40%. The tannic acid aqueous solution used had a concentration of 5 parts by weight of tannic acid solids per 100 parts by weight of aqueous solution. The iodine solution (liquid I2) used had a concentration of 0.1%.

[0157] EDTA was mixed at 0.1 parts by weight of solid content per 100 parts by weight of base resin, tannic acid was mixed at 0.015 parts by weight of solid content per 100 parts by weight of base resin, and iodine solution was mixed at 0.1 parts by weight per 100 parts by weight of base resin. Then, a drying step was carried out at 80°C for 25 minutes.

[0158] Example 5 A surface-treated superabsorbent resin was produced in the same manner as in Example 1.

[0159] The surface-treated superabsorbent resin was mixed with EDTA, tannic acid, and iodine solution in aqueous solution form. The EDTA aqueous solution used had a solids concentration of 40%. The tannic acid aqueous solution used had a concentration of 5 parts by weight of tannic acid solids per 100 parts by weight of aqueous solution. The iodine solution (liquid I2) used had a concentration of 0.1%.

[0160] EDTA was mixed at 1 part by weight of solid content per 100 parts by weight of base resin, tannic acid was mixed at 0.015 parts by weight based on solid content per 100 parts by weight of base resin, and iodine solution was mixed at 0.1 parts by weight per 100 parts by weight of base resin. Then, a drying step was carried out at 80°C for 25 minutes.

[0161] Example 6 A surface-treated superabsorbent resin was produced in the same manner as in Example 1.

[0162] The surface-treated superabsorbent resin was mixed with EDTA, tannic acid, and iodine solution in aqueous solution form. The EDTA aqueous solution used had a solids concentration of 40%. The tannic acid aqueous solution used had a concentration of 5 parts by weight of tannic acid solids per 100 parts by weight of aqueous solution. The iodine solution (liquid I2) used had a concentration of 0.1%.

[0163] EDTA was mixed at 2 parts by weight of solid content per 100 parts by weight of base resin, tannic acid was mixed at 0.015 parts by weight of solid content per 100 parts by weight of base resin, and iodine solution was mixed at 0.1 parts by weight per 100 parts by weight of base resin.Then, a drying step was carried out at 80°C for 25 minutes.

[0164] Example 7 A surface-treated superabsorbent resin was produced in the same manner as in Example 1.

[0165] The surface-treated superabsorbent resin was mixed with EDTA, tannic acid, and iodine solution in aqueous solution form. The EDTA aqueous solution used had a solids concentration of 40%. The tannic acid aqueous solution used had a concentration of 5 parts by weight of tannic acid solids per 100 parts by weight of aqueous solution. The iodine solution (liquid I2) used had a concentration of 0.1%.

[0166] EDTA was mixed at 0.5 parts by weight of solid content per 100 parts by weight of base resin, tannic acid was mixed at 0.015 parts by weight of solid content per 100 parts by weight of base resin, and iodine solution was mixed at 0.05 parts by weight per 100 parts by weight of base resin. Then, a drying step was carried out at 80°C for 25 minutes.

[0167] Example 8 A surface-treated superabsorbent resin was produced in the same manner as in Example 1.

[0168] The surface-treated superabsorbent resin was mixed with EDTA, tannic acid, and iodine solution in aqueous solution form. The EDTA aqueous solution used had a solids concentration of 40%. The tannic acid aqueous solution used had a concentration of 5 parts by weight of tannic acid solids per 100 parts by weight of aqueous solution. The iodine solution (liquid I2) used had a concentration of 0.1%.

[0169] EDTA was mixed at 0.5 parts by weight of solid content per 100 parts by weight of base resin, tannic acid was mixed at 0.015 parts by weight of solid content per 100 parts by weight of base resin, and iodine solution was mixed at 0.5 parts by weight per 100 parts by weight of base resin. Then, a drying step was carried out at 80°C for 25 minutes.

[0170] Example 9 A sheet-shaped hydrogel polymer was produced in the same manner as in Example 1.

[0171] The sheet-shaped hydrogel polymer was cut into thin strips, and an EDTA aqueous solution (40% concentration) was sprayed onto the cut hydrogel polymer and mixed with it by chopping (hole size: 16 mm) so that the EDTA solid content was 0.5 parts by weight based on 100 parts by weight of the base resin.

[0172] The water content of the chopped hydrogel polymer was 47% by weight. The hydrogel polymer was then dried in a hot air dryer at 185°C for 30 minutes, and the dried hydrogel polymer was pulverized in a pin mill pulverizer. The polymer was then sieved to produce a base resin with a particle size range of 150µm to 850µm.

[0173] Next, 100 parts by weight of the prepared base resin was uniformly mixed with a surface cross-linking 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)), and the mixture was subjected to a surface cross-linking reaction at 140°C for 30 minutes. After the surface treatment was completed, a superabsorbent resin with a particle size range of 150 to 850 μm was obtained using a sieve.

[0174] The surface-treated superabsorbent resin was mixed with tannic acid and iodine solution in the form of an aqueous solution. The tannic acid solution used had a concentration of 5 parts by weight of tannic acid solids based on 100 parts by weight of the aqueous solution. The iodine solution (liquid I2) used had a concentration of 0.1%.

[0175] Tannic acid was mixed in an amount of 0.015 parts by weight based on the solid content for 100 parts by weight of the base resin, and iodine solution was mixed in an amount of 0.5 parts by weight based on 100 parts by weight of the base resin, followed by a drying step at 80°C for 25 minutes.

[0176] Example 10 A surface-treated superabsorbent resin was produced in the same manner as in Example 1.

[0177] The surface-treated superabsorbent resin was mixed with EDTA, tannic acid, and iodine solution in aqueous solution form. The EDTA aqueous solution used had a solids concentration of 40%. The tannic acid aqueous solution used had a tannic acid solids concentration of 5 parts by weight based on 100 parts by weight of the aqueous solution. The iodine solution (liquid I2) used had a concentration of 0.1%.

[0178] EDTA was mixed at 0.5 parts by weight of solid content per 100 parts by weight of base resin, tannic acid was mixed at 0.015 parts by weight of solid content per 100 parts by weight of base resin, and iodine solution was mixed at 0.1 parts by weight per 100 parts by weight of base resin. Then, a drying step was carried out at 80°C for 25 minutes.

[0179] Example 11 A surface-treated superabsorbent resin was produced in the same manner as in Example 1.

[0180] The surface-treated superabsorbent resin was mixed with EDTA, tannic acid, iodine solution, and glycine in aqueous solution form. The EDTA aqueous solution used had a concentration of 40%. The tannic acid aqueous solution used had a concentration of 5 parts by weight of tannic acid solids based on 100 parts by weight of the aqueous solution. The iodine solution (liquid I2) used had a concentration of 0.1%. The glycine aqueous solution used had a concentration of 10%.

[0181] EDTA was mixed at 0.5 parts by weight of solid content per 100 parts by weight of base resin, tannic acid at 0.015 parts by weight of solid content per 100 parts by weight of base resin, iodine solution at 0.1 parts by weight per 100 parts by weight of base resin, and glycine at 0.018 parts by weight of solid content per 100 parts by weight of base resin.The mixture was then dried at 80°C for 25 minutes.

[0182] Example 12 A surface-treated superabsorbent resin was produced in the same manner as in Example 1.

[0183] The surface-treated superabsorbent resin was mixed with EDTA, tannic acid, iodine solution, and glycerin in aqueous solution form. The EDTA aqueous solution used had a concentration of 40%. The tannic acid aqueous solution used had a concentration of 5 parts by weight of tannic acid solids per 100 parts by weight of aqueous solution. The iodine solution (liquid I2) used had a concentration of 0.1%. The glycerin aqueous solution used had 10 parts by weight of glycerin per 100 parts by weight of aqueous solution.

[0184] EDTA was mixed at 0.5 parts by weight of solid content per 100 parts by weight of base resin, tannic acid at 0.015 parts by weight of solid content per 100 parts by weight of base resin, iodine solution at 0.1 parts by weight per 100 parts by weight of base resin, and glycerin at 0.03 parts by weight of solid content per 100 parts by weight of base resin.The mixture was then dried at 80°C for 25 minutes.

[0185] Comparative Example 2 A monomer aqueous solution composition with a monomer concentration of 45.8 wt% was prepared by mixing 100 g of acrylic acid, 0.37 g of N,N'-methylenebisacrylamide as a crosslinker, 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. The monomer aqueous solution composition was then introduced into the feed section of a polymerization reactor equipped with a continuously moving conveyor belt, and irradiated with ultraviolet light (irradiation dose: 10 mW / cm) using a UV irradiation device while maintaining the polymerization atmosphere temperature at 80°C. 2 ) and UV polymerization was carried out for 2 minutes to produce a sheet-shaped hydrogel polymer.

[0186] The sheet-shaped hydrogel polymer was cut into thin strips, and an EDTA aqueous solution (40% concentration) was sprayed onto the cut hydrogel polymer and mixed with it by chopping (hole size: 16 mm) so that the EDTA solid content was 0.5 parts by weight based on 100 parts by weight of the base resin.

[0187] The water content of the chopped hydrogel polymer was 47% by weight. The hydrogel polymer was then dried in a hot air dryer at 185°C for 30 minutes, and the dried hydrogel polymer was pulverized in a pin mill pulverizer. The polymer was then sieved to produce a base resin with a particle size range of 150µm to 850µm.

[0188] Next, 100 parts by weight of the prepared base resin was uniformly mixed with a surface cross-linking 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)), and the mixture was subjected to a surface cross-linking reaction at 140°C for 30 minutes. After the surface treatment was completed, a superabsorbent resin with a particle size range of 150 to 850 μm was obtained using a sieve.

[0189] Comparative Example 3 A surface-treated superabsorbent resin was produced in the same manner as in Comparative Example 1.

[0190] The surface-treated superabsorbent resin was mixed with glycerin in the form of an aqueous solution, the concentration of which was 10 parts by weight of glycerin per 100 parts by weight of the aqueous solution.

[0191] Glycerin was mixed at 0.03 parts by weight per 100 parts by weight of the base resin, followed by a drying step at 80°C for 25 minutes.

[0192] Comparative Example 4 A surface-treated superabsorbent resin was produced in the same manner as in Comparative Example 1.

[0193] The surface-treated superabsorbent polymer was mixed with tannic acid and glycerin in the form of an aqueous solution. The tannic acid aqueous solution had a concentration of 5 parts by weight of tannic acid solids per 100 parts by weight of the aqueous solution. The glycerin aqueous solution had a concentration of 10 parts by weight of glycerin per 100 parts by weight of the aqueous solution.

[0194] Tannic acid was mixed in an amount of 0.015 parts by weight based on the solid content for 100 parts by weight of the base resin, and glycerin was mixed in an amount of 0.03 parts by weight based on the solid content for 100 parts by weight of the base resin, followed by a drying step at 80°C for 25 minutes.

[0195] Comparative Example 5 A surface-treated superabsorbent resin was produced in the same manner as in Comparative Example 1.

[0196] The surface-treated superabsorbent resin was mixed with EDTA and tannic acid in the form of an aqueous solution. The EDTA aqueous solution used had a concentration of 40%. The tannic acid aqueous solution used had a concentration of 5 parts by weight of tannic acid solids based on 100 parts by weight of the aqueous solution.

[0197] EDTA was mixed in an amount of 0.5 parts by weight of solid content per 100 parts by weight of the base resin, and tannic acid was mixed in an amount of 0.015 parts by weight of solid content per 100 parts by weight of the base resin, followed by a drying step at 80°C for 25 minutes.

[0198] Comparative Example 6 A surface-treated superabsorbent resin was produced in the same manner as in Comparative Example 1.

[0199] The surface-treated superabsorbent resin was mixed with glycine in the form of an aqueous solution, the concentration of which was 10%.

[0200] Glycine was mixed at 0.018 parts by weight per 100 parts by weight of the base resin, followed by a drying step at 80°C for 25 minutes.

[0201] Comparative Example 7 A surface-treated superabsorbent resin was produced in the same manner as in Comparative Example 1.

[0202] The surface-treated superabsorbent resin was mixed with EDTA and glycerin in the form of an aqueous solution. The EDTA aqueous solution used had a concentration of 40%. The glycerin aqueous solution used had a concentration of 10 parts by weight of glycerin per 100 parts by weight of the aqueous solution.

[0203] EDTA was mixed at a solid content of 0.5 parts by weight per 100 parts by weight of the base resin, and glycerin was mixed at a solid content of 0.03 parts by weight per 100 parts by weight of the base resin, followed by a drying step at 80°C for 25 minutes.

[0204] Comparative Example 8 A surface-treated superabsorbent resin was produced in the same manner as in Comparative Example 1.

[0205] The surface-treated superabsorbent resin was mixed with tannic acid in the form of an aqueous solution, the concentration of which was 5 parts by weight of tannic acid solids per 100 parts by weight of the aqueous solution.

[0206] Tannic acid was mixed in an amount of 0.015 parts by weight based on solid content to 100 parts by weight of the base resin, followed by a drying step at 80°C for 25 minutes.

[0207] Comparative Example 9 A surface-treated superabsorbent resin was produced in the same manner as in Comparative Example 1.

[0208] The surface-treated superabsorbent resin was mixed with an iodine solution (liquid I2). The iodine solution used was an aqueous solution with a concentration of 0.1%.

[0209] The iodine solution was mixed at 0.1 parts by weight per 100 parts by weight of the base resin, followed by a drying step at 80°C for 25 minutes.

[0210] Comparative Example 10 A surface-treated superabsorbent resin was produced in the same manner as in Comparative Example 1.

[0211] The surface-treated superabsorbent resin was mixed with tannic acid and iodine solution (liquid I2). The tannic acid solution used had a concentration of 5 parts by weight of tannic acid solids based on 100 parts by weight of the solution. The iodine solution used had a concentration of 0.1%.

[0212] Tannic acid was mixed in an amount of 0.015 parts by weight based on solid content for 100 parts by weight of the base resin. Iodine solution was mixed in an amount of 0.1 parts by weight for 100 parts by weight of the base resin. Then, a drying step was carried out at 80°C for 25 minutes.

[0213] Comparative Example 11 A surface-treated superabsorbent resin was produced in the same manner as in Comparative Example 1.

[0214] The surface-treated superabsorbent resin was mixed with an EDTA aqueous solution and an iodine solution (liquid I2). The EDTA aqueous solution used had a concentration of 40%. The iodine solution used had a concentration of 0.1%.

[0215] EDTA was mixed at 0.5 parts by weight of solid content to 100 parts by weight of base resin, and iodine solution was mixed at 0.1 parts by weight to 100 parts by weight of base resin, followed by a drying step at 80°C for 25 minutes.

[0216] Tables 1 and 2 below summarize the conditions for the examples and comparative examples.

[0217] [Table 1]

[0218] [Table 2]

[0219] Experimental Example The superabsorbent resin compositions prepared in the above Examples and Comparative Examples were measured for various physical properties by the following methods.

[0220] 1) Bacterial suppression rate 50 ml of artificial urine inoculated with 3,000 CFU / ml of E. coli was added to 2 g of the EDTA-free superabsorbent resin of Comparative Example 1, and then cultured in an incubator at 35°C for 12 hours. After the culture was completed, the sample was thoroughly washed with 150 ml of saline (0.9 wt% sodium chloride solution) and cultured on a Nutrient Broth Agar (BD DIFCO) plate to measure the CFU (Colony Forming Unit; CFU / ml), which was calculated as the physical property of the control group.

[0221] Two grams of the superabsorbent resin prepared in the above Examples or Comparative Examples was added to 50 ml of artificial urine inoculated with 3,000 CFU / ml of E. coli and incubated in an incubator at 35°C for 12 hours. After incubation, 150 ml of saline (0.9 wt% sodium chloride solution) was added to the sample and shaken for one minute to ensure uniform mixing. The resulting diluted solution was smeared on a Nutrient Broth Agar (BD DIFCO.) plate and incubated in an incubator at 30°C for 24 hours, after which the CFU (Colony Forming Unit; CFU / ml) was measured.

[0222] Using these measurement results, the bacterial growth inhibition rate defined by the following formula 1 was calculated, and the antibacterial activity of the superabsorbent resins of each example and comparative example was evaluated based on this.

[0223] [Formula 1] Bacterial growth inhibition rate = [1-{CFU(12 hours) / CFU control(12 hours)}]×100(%)

[0224] In the above formula 1, CFU (12 hours) indicates the number of bacteria per unit volume (CFU / ml) of artificial urine that has been inoculated with E. coli bacteria, and the superabsorbent resin is added to the artificial urine, which is then cultured at 35°C for 12 hours. CFU control (12 hours) indicates the number of bacteria grown per unit volume of artificial urine (CFU / ml) when artificial urine inoculated with the bacteria is cultured under the same conditions on a superabsorbent resin that does not contain EDTA, i.e., the number of bacteria grown per unit volume of artificial urine (CFU / ml) measured for the control group.

[0225] 2) Deodorization rate The deodorizing rate was measured using an adsorption tube method. 3-methylbutanal was selected as an aldehyde-based malodorous substance, and dimethyltrisulfide (DMTS) was selected as a sulfur compound-based malodorous substance to test the deodorizing power.

[0226] - Adsorption tube measurement method: 1g of superabsorbent resin was placed in a 500mL glass bottle, and 25mL of malodorous substances were poured into it. After aging for 3 hours in a constant temperature chamber, the bottle was collected for 20 minutes. The temperature of the constant temperature chamber was 35℃ and the N2 flow rate was 250mL / min. The extruded malodorous substances were then adsorbed into the connected adsorption tube, and this process was repeated twice for each sample. The collection results were confirmed by GC analysis.

[0227] Deodorizing power (%) = (amount of malodor of the reference sample (superabsorbent polymer of Comparative Example 1) measured by GC - amount of malodor of the sample measured by GC) / amount of malodor of the reference sample (superabsorbent polymer of Comparative Example 1) measured by GC × 100 (%)

[0228] 3)Centrifuge Retention Capacity (CRC) The water retention capacity of each resin was measured in terms of its water absorption capacity under no load according to the European Disposables and Nonwovens Association (EDANA) standard, EDANA WSP 241.3.

[0229] Specifically, resins classified into particle sizes ranging from 300 to 600 μm were obtained from the resins obtained in the examples and comparative examples. W0 (g) (approximately 0.2 g) of such resins was uniformly placed in a nonwoven fabric envelope, sealed, and then immersed in physiological saline (0.9 wt%) at room temperature. After 30 minutes, the envelope was centrifugally dewatered at 250 G for 3 minutes, and the mass of the envelope, W2 (g), was measured. The same procedure was repeated without using the resin, and the mass, W1 (g), was then measured.

[0230] The CRC (g / g) was calculated using the obtained masses according to the following formula 1.

[0231] [Formula 1] CRC(g / g)={[W2(g)-W1(g)] / W0(g)}-1

[0232] 4) Absorbency under Pressure (AUP) The water absorption capacity of the superabsorbent resins of the above Examples and Comparative Examples at a pressure of 0.7 psi was measured by the EDANA method WSP 242.3.

[0233] First, when measuring the water absorption capacity under pressure, the resin-classified powder used in the CRC measurement was used.

[0234] Specifically, a 400-mesh stainless steel iron net was attached to the bottom of a plastic cylinder with an inner diameter of 25 mm. A superabsorbent resin (W0) (g) was evenly spread on the iron net under conditions of room temperature and 50% humidity, and a piston capable of applying a uniform load of 0.7 psi to the resin was slightly smaller than the outer diameter of 25 mm, had no gap with the inner wall of the cylinder, and did not interfere with up-and-down movement. The weight of the device, W3 (g), was then measured.

[0235] A glass filter with a diameter of 90 mm and a thickness of 5 mm was placed inside a 150 mm diameter petroleum dish, and physiological saline solution composed of 0.9 wt% sodium chloride was placed at the same level as the top surface of the glass filter. A sheet of filter paper with a diameter of 90 mm was placed on top of it. The measuring device was placed on top of the filter paper and allowed to absorb the liquid under load for 1 hour. After 1 hour, the measuring device was lifted and its weight W4 (g) was measured. The pressurized water absorption capacity (g / g) was calculated using the obtained masses according to the following formula 2.

[0236] [Formula 2] AUP(g / g) = [W4(g) - W3(g)] / W0(g)

[0237] 5) Gel Strength (N) Among the superabsorbent polymers, those having particle sizes of 150 μm to 850 μm were taken, and 2.5 g of the superabsorbent polymer was immersed in 50 g of ascorbate water and allowed to swell in a 40°C oven for 2 hours and 4 hours, after which the gel strength of the swollen superabsorbent polymer was measured using a tensile / compression tester.

[0238] Specifically, the swollen superabsorbent resin was measured using a digital force gauge FGP-2, which is a tension and compression tester. The peak value of the force (N) applied to the tip while the tip was penetrating was measured three times under the following conditions, and the arithmetic mean value was taken as the gel strength (unit: N).

[0239] Tip size: Terminal diameter 10±0.1mm Beaker size: 50±0.1mm Penetration speed: 500±0.5mm / min

[0240] The experimental results are shown in Table 3.

[0241] [Table 3]

[0242] From the results in Table 3, it can be seen that the Example has a similar level of water absorption capacity to Comparative Example 1, which does not contain any additives, while exhibiting superior bacteria inhibition rate and deodorization rate. In addition, it can be seen that the Example 1 also has superior gel strength compared to Comparative Examples 1, 2, and 8.

[0243] In addition, in the case of Comparative Example 2, in which only a chelating agent was used without a deodorizing substance, the bacterial inhibition rate was at a similar level, but the deodorizing rate was very poor, and in the Comparative Example, in which only a deodorizing substance was used without a chelating agent, bacteria could not be inhibited at all, and the deodorizing rate also tended to be lower than in the Examples.

[0244] On the other hand, unlike the comparative examples, the superabsorbent resins of the examples have excellent bacterial inhibition rates and deodorizing rates, and it was confirmed that the water absorption capacity, which is an inherent physical property of the superabsorbent resin, is not reduced and excellent gel strength is maintained.

[0245] It is assumed that the iodine ions of the iodine compounds contained in the examples change the ascorbic acid components in urine and other body fluids, thereby preventing the gel-inhibiting function of ascorbic acid. In addition, it is known that chelating agents contribute to a certain degree to the gel strength improvement effect by binding with metal ions, and it was confirmed that the gel strength was improved by combining them.

Claims

1. a superabsorbent resin comprising: a base resin containing a crosslinked polymer obtained by crosslinking an acrylic acid-based monomer having at least a partially neutralized acidic group with an internal crosslinking agent; and a surface crosslinked layer formed on the surface of the base resin, the surface crosslinked layer being obtained by additional crosslinking of the crosslinked polymer via a surface crosslinking agent; Tannic acid; iodine compounds; and chelating agents; Super absorbent resin composition.

2. For 100 parts by weight of the base resin, The tannic acid is contained in an amount of more than 0.001 to 0.5 parts by weight based on the solid content. The highly water-absorbent resin composition according to claim 1.

3. For 100 parts by weight of the base resin, The iodine compound is contained in an amount of 0.01 to 1.0 parts by weight. The highly water-absorbent resin composition according to claim 1.

4. For 100 parts by weight of the base resin, The chelating agent is included in an amount of 0.05 to 4.0 parts by weight based on the solid content. The highly water-absorbent resin composition according to claim 1.

5. The chelating agent includes an aminoacetate-based chelating agent. The highly water-absorbent resin composition according to claim 1.

6. The aminoacetate chelating agent includes at least one selected from the group consisting of ethylenediaminetetraacetic acid (EDTA), L-glutamic acid diacetic acid (GLDA), methylglycine diacetic acid (MGDA), hydroxyethylethylenediaminetriacetic acid (HEDTA), ethanoldiglycine acid (EDG), diethylenetriaminepentaacetic acid (DTPA), and salts thereof; The highly water-absorbent resin composition according to claim 5.

7. The superabsorbent polymer composition further contains one or more additives selected from the group consisting of organic acids, glycerin, and zinc chloride. The highly water-absorbent resin composition according to claim 1.

8. The tannic acid and the iodine compound are added separately from the superabsorbent polymer, and The chelating agent is contained within the base resin or separately from the superabsorbent resin. The highly water-absorbent resin composition according to claim 1.

9. Step 1: forming a hydrogel polymer by cross-linking and polymerizing an acrylic acid monomer having at least a partially neutralized acid group in the presence of an internal cross-linking agent and a polymerization initiator; Step 2: preparing a base resin containing a crosslinked polymer by coarsely pulverizing, drying, and pulverizing the hydrogel polymer; Step 3: mixing the base resin with a surface cross-linking agent to prepare a mixture; and Step 4: heat-treating the mixture to prepare a superabsorbent resin having a surface cross-linked layer formed on the surface of the base resin; Tannic acid and an iodine compound are mixed with the superabsorbent resin on which the surface cross-linked layer of step 4 has been formed, The chelating agent is mixed in the coarse grinding step of step 2, or mixed into the superabsorbent resin on which the surface cross-linked layer has been formed in step 4. A method for producing a superabsorbent polymer composition.

10. For 100 parts by weight of the base resin, The tannic acid is mixed in an amount of more than 0.001 to 0.5 parts by weight based on the solid content. A method for producing the highly water-absorbent polymer composition according to claim 9.

11. For 100 parts by weight of the base resin, The iodine compound is mixed in an amount of 0.01 to 1.0 parts by weight. A method for producing the highly water-absorbent polymer composition according to claim 9.

12. For 100 parts by weight of the base resin, The chelating agent is mixed in an amount of 0.05 to 4.0 parts by weight based on the solid content. A method for producing the highly water-absorbent polymer composition according to claim 9.

13. The chelating agent includes an aminoacetate-based chelating agent. A method for producing the highly water-absorbent polymer composition according to claim 9.

14. The aminoacetate chelating agent includes at least one selected from the group consisting of ethylenediaminetetraacetic acid (EDTA), L-glutamic acid diacetic acid (GLDA), methylglycine diacetic acid (MGDA), hydroxyethylethylenediaminetriacetic acid (HEDTA), ethanoldiglycine acid (EDG), diethylenetriaminepentaacetic acid (DTPA), and salts thereof; A method for producing the highly water-absorbent polymer composition according to claim 13.

15. After step 4, the superabsorbent resin having the surface cross-linked layer formed thereon is further mixing one or more additives selected from the group consisting of organic acids, glycerin, and zinc chloride; A method for producing the highly water-absorbent polymer composition according to claim 9.

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