Patent Description:
A superabsorbent polymer (SAP) is a synthetic polymer material that can absorb moisture of <NUM> to <NUM> times its own weight, and is also called a superabsorbent material (SAM), an absorbent gel material (AGM), etc. according to developing companies. The superabsorbent polymer began to be commercialized for sanitary items, and currently, it is being widely used for hygienic goods such as disposable diapers and the like, waterholding materials for soil, water stop materials for civil engineering and architecture, sheets for raising seedlings, freshness preservatives in the field of food circulation, fomentation materials, and the like, or in the field of electrical insulation.

Such a superabsorbent polymer is most widely applied for hygienic goods or disposable absorption products such as child diapers or adult diapers. Among them, in a case of being applied for adult diapers, secondary odors resulting from bacterial growth gives consumers significant discomfort. In order to solve this problem, there have been attempts to introduce various deodorizing or antimicrobial functional components into a superabsorbent polymer composition before.

However, in the existing attempts to introduce various deodorizing/antimicrobial functional components, even if the superabsorbent polymer exhibits deodorizing/antimicrobial properties, a lot of dust may be generated during the process, thus deteriorating processability and workability. Further, the existing method has disadvantages in that the stability of the superabsorbent polymer may be deteriorated, and the unit cost of a superabsorbent polymer composition may be excessively increased due to the high costs of functional components. Therefore, there is a continued demand for the development of a superabsorbent polymer composition that exhibits more improved antimicrobial and deodorizing properties without deterioration of basic absorption performance, and fulfills both stability and processability as well as excellent economic efficiency.

<CIT> discloses granular composites including superabsorbent polymer, a silicate, a water-soluble polymer and odor control agents, wherein the water-soluble polymer can preferably be an organic acid, and the odor control agent may be a chelating agent.

<CIT> discloses disposable absorbent hygiene products, comprising an absorbent core comprising a superabsorbent polymer and dedusting agents, which may be mineral oil, baby oil, corn oil, olive oil, rapeseed oil, soybean oil, sunflower oil, or an ester, alcohol, acid, or a mixture thereof. The dedusted compositions may be further blended with a particulate flowability enhancer such as silica.

<CIT> discloses disposal absorbent articles for retaining malodorous body fluids. The absorbent articles comprise an additive, a quaternary ammonium salt and odor-reducing compounds such as acids, silica, chelating agents and anti-microbials.

It is an object of the present invention to provide a superabsorbent polymer composition that exhibits improved antimicrobial and deodorizing properties without deterioration of basic absorption performance, and particularly, significantly reduces the generation of dust during the process, and thus can fulfill both stability and processability, and hygienic goods including the same.

The present invention provides a superabsorbent polymer composition including:.

Further embodiments are disclosed in the dependent claims,.

According to the superabsorbent polymer composition, a highly improved antimicrobial property to bacteria inducing odor in hygienic goods such as an adult diaper and the like can be provided, and the resulting deodorizing property can be exhibited without deterioration of basic absorption performance such as centrifugal retention capacity, absorbency under pressure, and the like.

Particularly, the present invention provides a method for fulfilling both stability and processability by significantly reducing the generation of dust during the preparation process of a superabsorbent polymer without deterioration of antimicrobial efficiency, even if using an agent for controlling a particle size.

The terms used herein are only to explain specific embodiments, and are not intended to limit the present invention.

A singular expression includes a plural expression thereof, unless it is expressly stated or obvious from the context that such is not intended.

As used herein, the terms "comprise", "have", etc. are intended to designate the existence of a practiced characteristic, number, step, constructional element, or combinations thereof, and they are not intended to preclude the possibility of existence or addition of one or more other characteristics, numbers, steps, constructional elements, or combinations thereof.

Hereinafter, a superabsorbent polymer composition according to specific embodiments of the present invention will be explained in more detail.

A superabsorbent polymer composition according to one embodiment of the invention includes:.

First, throughout the specification, the term "antimicrobial agent having a controlled particle size" means an additive performing a function for inhibiting the generation of dust in a process, by increasing the content rate of superabsorbent polymer powders of <NUM> to <NUM> in the particle size distribution compared to the prior art, by using an agent for controlling a particle size.

That is, by using the antimicrobial agent having a controlled particle size, in the distribution rate of a) powders having a particle size of <NUM> or more, b) powders having a particle size of <NUM> to <NUM>, c) powders having a particle size of <NUM> to <NUM>, d) powders having a particle size of <NUM> to <NUM>, e) powders having a particle size of <NUM> to <NUM>, and f) powders having a particle size of less than <NUM>, the content rate of superabsorbent polymer powders of <NUM> to <NUM> may be increased by <NUM> wt% or more compared to the prior art, and the content of powders having a particle size of less than <NUM> may be decreased. Further, the antimicrobial agent having a controlled particle size means a mixture of three components including a chelating agent including EDTA or an alkali metal salt thereof, a mixture of an organic acid and a silicate-based salt, and an agent for controlling a particle size, which affords an antimicrobial function to the superabsorbent polymer particles.

According to the superabsorbent polymer composition of one embodiment, by using an agent for controlling a particle size in an antimicrobial agent containing a chelating agent including EDTA or an alkali metal salt thereof having a relatively low unit cost, and a mixture of an organic acid and a silicate-based salt, improved deodorizing/antimicrobial properties can be exhibited. Particularly, according to the result of continued experiments by the present inventors, by adding an antimicrobial agent having a controlled particle size obtained by mixing the above-explained three components to superabsorbent polymer particles, the inhibition of growth of bacteria acting as an offensive odor component in an adult diaper and the like can be very effectively inhibited, and simultaneously, dust generated during the application of a process can be significantly reduced. As the result, it was confirmed that the superabsorbent polymer composition of one embodiment may have improved workability and processability without deterioration of excellent antimicrobial and deodorizing properties.

Furthermore, when preparing a superabsorbent polymer having an antimicrobial property, although it is better as the content of an antimicrobial agent is higher, when materials other than the superabsorbent polymer are added, property deterioration may be caused, but in the present invention, due to the use of an optimum amount of an agent for controlling a particle size, dust can be reduced while simultaneously obtaining excellent antimicrobial efficiency. Further, an antimicrobial agent such as a chelating agent added to achieve the antimicrobial property may become a direct cause of dust, but the present invention can remarkably reduce the content of dust in the superabsorbent polymer composition compared to the prior art by adding an antimicrobial agent having a controlled particle size, when compared with the existing antimicrobial agent of the same content.

Thus, the present invention uses an agent for controlling a particle size in an antimicrobial mixture, thereby increasing a particle size and reducing dust, which indicates that the antimicrobial mixture is not eliminated from SAP particles.

In addition, these components do not inhibit the stability of the superabsorbent polymer composition, and thus the superabsorbent polymer composition of one embodiment can maintain excellent basic absorption performance and the unit costs are relatively low, thus largely contributing to the low unit cost and economic efficiency of the superabsorbent polymer composition.

Therefore, the superabsorbent polymer composition of one embodiment can be very preferably applied for various hygienic goods such as an adult diaper and the like.

Hereinafter, each component of the superabsorbent polymer composition of one embodiment will be explained in detail.

The agent for controlling a particle size is included in a content of <NUM> to <NUM> parts by weight, based on <NUM> parts by weight of the sum of the chelating agent, and the mixture of the organic acid and the silicate-based salt.

The superabsorbent polymer composition of one embodiment may include a chelating agent including EDTA or an alkali metal salt thereof, and a mixture of organic acid and a silicate-based salt, so as to achieve unique antimicrobial/deodorizing effects. The chelating agent may include a sodium salt of EDTA-2Na or EDTA-4Na. Further, the chelating agent may further include one or more selected from the group consisting of cyclohexane diamine tetraacetic acid, diethylene triamine pentaacetic acid, ethylene glycol-bis-(aminoethylether)-N,N,N'-triacetic acid, N-(<NUM>-hydroxyethyl)-ethylene diamine-N,N,N'-triacetic acid, triethylene tetraamine hexaacetic acid, and alkali metal salts thereof.

Such a chelating agent may exist on the superabsorbent polymer particles to cause a synergistic effect with the mixture of an organic acid and a silicate-based salt, and as the result, the superabsorbent polymer composition of one embodiment may exhibit improved deodorizing/antimicrobial properties.

More specifically, the chelating agent can act as an antimicrobial agent that inhibits the growth rate of various bacteria, particularly, the growth of odor-causing Proteus mirabilis bacteria. However, despite the growth inhibition action of the chelating agent, some bacteria may remain, thereby generating offensive odors due to the generation of ammonia and the like. Such odor may be mostly removed by a mixture of an organic acid and a silicate-based salt, and thus the superabsorbent polymer composition of one embodiment may exhibit excellent deodorizing/antibacterial properties by the synergistic effect of two components.

The chelating agent is included in the content of <NUM> to <NUM> parts by weight, preferably <NUM> to <NUM> parts by weight, or <NUM> to <NUM> parts by weight, based on <NUM> parts by weight of the superabsorbent polymer particles. By using the chelating agent, the growth rate of odor-causing Proteus mirabilis may be appropriately inhibited, and thus an excellent antimicrobial property may be exhibited, and a preferable range of the antimicrobial property (CFU/ml) may be exhibited. Urea is converted into ammonia by Proteus mirabilis, and by inhibiting the growth of this bacterium, the amount of ammonia generated may be basically controlled to be low. Thus, the superabsorbent polymer composition of one embodiment may exhibit excellent antimicrobial/deodorizing properties. However, if the content of the chelating agent becomes too high, even bacteria beneficial to the human body may be removed, or the stability or the absorption property of the superabsorbent polymer may be deteriorated.

Meanwhile, the superabsorbent polymer composition of one embodiment includes a mixture of an organic acid and a silicate-based salt. Such organic acid and silicate-based salt may also exist on the superabsorbent polymer particles.

Such a silicate-based salt may be in the form of a salt in which a silicate anion, and an alkali metal or an alkali earth metal cation, are ionically bonded, and it may exist in the state of particles. Such silicate salt particles may include particles having a particle diameter of <NUM> or more and less than <NUM> in the content of about <NUM> to about <NUM> wt%, about <NUM> to about <NUM> wt%, or about <NUM> to about <NUM> wt%.

The organic acid mixed with the silicate-based salt may exist on the superabsorbent polymer particles in the state of particles having a particle diameter of <NUM> or less, or <NUM> to <NUM>.

When the organic acid and silicate-based salt have the above-described particle states and particle size distributions, they may be appropriately maintained on the superabsorbent polymer particles, and thus can more selectively and effectively adsorb bacteria/offensive odor components to physically/chemically remove them. As the result, the superabsorbent polymer of one embodiment may exhibit more improved antimicrobial/deodorizing properties. Furthermore, due to the particle states, when mixed with the superabsorbent polymer, anti-caking performance may be exhibited.

The organic acid is included in the content of <NUM> to <NUM> wt%, <NUM> to <NUM> wt%, or <NUM> to <NUM> wt%, based on the total weight of the mixture of an organic acid and a silicate-based salt. Thus, inside and/or on the surface of the superabsorbent polymer particles, a large number of acid sites may be generated. If such acid sites are included, various offensive odor components may be physically adsorbed, and the hydrogen cations (H+) of the acid sites may bond with offensive odor components to form ammonium salts, thereby more effectively removing offensive odor components.

The organic acid may include one or more selected from the group consisting of citric acid, fumaric acid, maleic acid, and lactic acid, but it is not limited thereto.

According to the present invention, the mixture of an organic acid and a silicate-based salt is included in the content of <NUM> to <NUM> parts by weight, preferably <NUM> to <NUM> parts by weight, or <NUM> to <NUM> parts by weight, based on <NUM> parts by weight of the superabsorbent polymer. If the contents of these components are too small, deodorizing property obtained by the organic acid and the like may not be sufficient, and if the contents are too large, the properties of the superabsorbent polymer may be deteriorated.

The mixture of an organic acid and a silicate-based salt may be prepared by a common method of mixing the organic acid and the silicate-based salt. Although such a mixture may be prepared by previously mixing these two components, each component may be mixed with a chelating agent after preparing superabsorbent polymer particles, as described below.

Meanwhile, in the present invention, an antimicrobial agent exhibiting antimicrobial/deodorizing effects is prepared through mixing of the above-explained three components, and an agent for controlling a particle size is added, thereby controlling the particle size of superabsorbent polymer particles, thus significantly reducing the generation of dust in the preparation process of the superabsorbent polymer.

That is, the conventional antimicrobial agent has a problem in that particles of #<NUM> or less (<NUM> or less) occupy <NUM> wt% and thus a lot fine dust is generated while mixing with the superabsorbent polymer. However, according to the present invention, by adding an agent for controlling a particle size to the chelating agent and the mixture of organic acid and silicate-based salt, particles of #<NUM> or less (<NUM> or less) exist in the content of <NUM> wt% or less, or preferably <NUM> wt% or less. Thus, the present invention can improve processability and workability, and simultaneously increase the content rate of superabsorbent polymer powders of <NUM> to <NUM> compared to the prior art.

Therefore, in the present invention, by using an agent for controlling a particle size, the particle size distribution range of <NUM> to <NUM> may be increased.

Herein, the agent for controlling a particle size is included in the content of <NUM> to <NUM> parts by weight, based on <NUM> parts by weight of the sum of the chelating agent and the mixture of organic acid and silicate-based salt. If the content of the agent for controlling a particle size is less than <NUM> parts by weight, there may be no dust decreasing effect, and if it is greater than <NUM> parts by weight, properties may be significantly deteriorated.

The agent for controlling a particle size may be one or more selected from the group consisting of mineral oil, natural oil, baby oil, corn oil, olive oil, and silicone oil. According to one preferable embodiment, the agent for controlling a particle size may be mineral oil.

In the present invention, by using the agent for controlling a particle size in an antimicrobial mixture, excellent antimicrobial efficiency may be maintained, a particle size may be increased, and the amount of dust generation, which can determine whether or not the antimicrobial mixture is eliminated from SAP particles, may be reduced.

The antimicrobial agent having a controlled particle size is included in the content of <NUM> to <NUM> parts by weight, based on <NUM> parts by weight of the superabsorbent polymer particles. Preferably, when the antimicrobial agent having a controlled particle size is included in the content of <NUM> to <NUM> parts by weight based on <NUM> parts by weight of the superabsorbent polymer particles, the particle size distribution of #<NUM> or less (<NUM> or less) may become <NUM> to less than <NUM> wt% based on the total weight, thereby more effectively reducing the generation of fine dust, and the content rate of the superabsorbent polymer powders of <NUM> to <NUM> may be increased to more than in the prior art. If the content of the antimicrobial agent having a controlled particle size is less than <NUM> parts by weight, there may be no antimicrobial effect, and if it is greater than <NUM> parts by weight, properties may be significantly deteriorated.

Thus, in the superabsorbent polymer composition of one embodiment, the above-explained antimicrobial agent having a controlled particle size may exist on the superabsorbent polymer particles.

Meanwhile, the kind or preparation method of the superabsorbent polymer that is mixed with the antimicrobial agent having a controlled particle size, which is a mixture of the above-explained three components, may be those commonly used in the art, and the steps and methods of mixing these components with the superabsorbent polymer are not specifically limited.

For example, the superabsorbent polymer may be obtained by progressing thermal polymerization or photopolymerization of a monomer composition including water soluble ethylenically unsaturated monomers and a polymerization initiator to obtain a hydrogel polymer, and drying, grinding, sieving, and if necessary, surface crosslinking or fine powder reassembly processing it, and the like, may be further conducted.

For reference, throughout the specification, "superabsorbent polymer" means to include a crosslinked polymer in which water-soluble ethylenically unsaturated monomers including acid groups, of which at least a part are neutralized, are polymerized; a base polymer made in the form of a powder by drying and grinding the crosslinked polymer; or those made suitable for the productization by subjecting the crosslinked polymer or base polymer to additional processes, for example, surface crosslinking, fine powder reassembly, drying, grinding, sieving, and the like, according to the context.

As the water-soluble ethylenically unsaturated monomers, any monomers commonly used for the preparation of a superabsorbent polymer may be used without specific limitations. As the water-soluble ethylenically unsaturated monomers, one or more monomers selected from the group consisting of anionic monomers and salts thereof, non-ionic hydrophilic group-containing monomers, amino group-containing unsaturated monomers, and quaternarized products thereof, may be used.

Specifically, one or more selected from the group consisting of anionic monomers and salts thereof such as acrylic acid, (meth)acrylic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, <NUM>-acryloylethane sulfonic acid, <NUM>-methacryloylethane sulfonic acid, <NUM>-(meth)acryloyl propane sulfonic acid, or <NUM>-(meth)acrylamid-<NUM>-methyl propane sulfonic acid; non-ionic hydrophilic group-containing monomers such as (meth)acrylamide, N-substituted (meth)acrylate, <NUM>-hydroxyethyl (meth)acrylate, <NUM>-hydroxypropyl (meth)acrylate, methoxy polyethylene glycol (meth)acrylate, or polyethylene glycol (meth)acrylate; and amino group-containing unsaturated monomers such as (N,N)-dimethylaminoethyl (meth)acrylate, (N,N)-dimethylaminopropyl (meth)acrylamide, and quaternarized products thereof, may be used.

More preferably, as the water soluble ethylenically unsaturated monomers, acrylic acid, or salts thereof, for example, acrylic acid or an alkali metal salt such as a sodium salts thereof may be used, and in case such monomers are used, a superabsorbent polymer having excellent properties can be prepared. In case an alkali metal salt of acrylic acid is used as the water soluble ethylenically unsaturated monomers, acrylic acid may be neutralized with a basic compound such as caustic soda (NaOH) before use.

A polymerization initiator that is used when polymerizing the water-soluble ethylenically unsaturated monomers is not specifically limited as long as it is commonly used for the preparation of a superabsorbent polymer.

Specifically, as the polymerization initiator, a thermal polymerization initiator or a photopolymerization initiator by UV irradiation may be used according to a polymerization method. However, even in the case of photopolymerization, since a certain amount of heat is generated by UV irradiation, etc., and heat is generated to some degree according to the progression of an exothermic polymerization reaction, a thermal polymerization initiator may be additionally included.

The photopolymerization initiator is not limited in terms of its construction, as long as it is a compound capable of forming a radical by light such as UV.

According to one embodiment of the invention, the monomer composition may further include an internal crosslinking agent as the raw material of the superabsorbent polymer.

As the internal crosslinking agent, a crosslinking agent having one or more functional groups capable of reacting with the water soluble substituents of the water soluble ethylenically unsaturated monomers, and having one or more ethylenically unsaturated groups; or a crosslinking agent having two or more functional groups capable of reacting with the water soluble substituents of the monomers and/or the water soluble substituents formed by the hydrolysis of the monomers, may be used.

As specific examples of the internal crosslinking agent, C8-<NUM> bisacrylamide, bismethacrylamide, C2-<NUM> polyol poly(meth)acrylate, C2-<NUM> polyol poly(meth)allylether, and the like may be mentioned, and more specifically, one or more selected from the group consisting of N,N'-methylene bis(methacrylate), ethylene oxy(methacrylate), polyethylene oxy(methacrylate), propylene oxy(methacrylate), glycerin diacrylate, glycerin triacrylate, trimethylol triacrylate, triallyl amine, triaryl cyanurate, triallyl isocyanate, polyethylene glycol, diethylene glycol, and propylene glycol may be used.

In the preparation method, the monomer composition may further include additives such as a thickener, a plasticizer, a preservation stabilizer, an antioxidant, etc., as necessary.

The above-explained raw materials such as water soluble ethylenically unsaturated monomers, a photopolymerization initiator, a thermal polymerization initiator, an internal crosslinking agent, and additives may be prepared in the form of a solution dissolved in a solvent.

Meanwhile, a method of forming a hydrogel polymer by the thermal polymerization or photopolymerization of the monomer composition is not specifically limited in terms of its construction, as long as it is a commonly used polymerization method.

Specifically, the polymerization method is largely classified into thermal polymerization and photopolymerization according to an energy source. Commonly, thermal polymerization may be progressed in a reactor equipped with a stirring axis such as a kneader, and photopolymerization may be progressed in a reactor equipped with a movable conveyer belt, but the above-explained polymerization methods are no more than examples, and the present invention is not limited thereto.

Here, the moisture content of hydrogel polymer obtained by such a method may be about <NUM> to about <NUM> wt%. Throughout the specification, the "moisture content" is the content of moisture occupied based on the total weight of the hydrogel polymer, and it means a value obtained by subtracting the weight of the polymer in a dry state from the weight of hydrogel polymer. Specifically, it is defined as a value calculated by measuring the weight loss according to moisture evaporation in the polymer while raising the temperature of the polymer through infrared heating to dry it. At this time, the drying condition is set such that the temperature is raised from room temperature to about <NUM> and then maintained at <NUM>, and the total drying time is <NUM> minutes including a temperature raising step of <NUM> minutes.

Next, the obtained hydrogel polymer is dried.

Herein, a coarse grinding step may be further conducted before drying the hydrogel polymer so as to increase drying efficiency.

Here, grinders that can be used in the coarse grinding are not limited in terms of their constructions, but specifically, one selected from the group 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 may be used, but the grinder is not limited thereto.

Through the coarse grinding step, the particle diameter of the hydrogel polymer may be controlled to about <NUM> to about <NUM>.

The hydrogel polymer coarsely ground as explained above, or the hydrogel polymer immediately after polymerization that is not subjected to the coarse grinding step, is dried.

The drying method is not limited in terms of the construction as long as it is commonly used as a drying process of a hydrogel polymer. Specifically, the drying step may be progressed by hot wind supply, infrared ray irradiation, ultrahigh frequency wave irradiation, UV irradiation, etc. The polymer dried by such a method may exhibit a moisture content of about <NUM> to about <NUM> wt%.

Next, the dried polymer obtained through the drying step is ground.

The particle diameter of the polymer powder obtained after the grinding step may be <NUM> to <NUM>. As a grinder for grinding to such a particle diameter, specifically, a pin mill, a hammer mill, a screw mill, a roll mill, a disc mill, a jog mill, etc. may be used, but the grinder is not limited thereto.

In order to manage the properties of the superabsorbent polymer powders finally productized after the grinding step, the polymer powders obtained after grinding may be subjected to a separate process of sieving according to the particle diameter. Preferably, polymer powders having a particle diameter of about <NUM> to about <NUM> are sieved.

According to one embodiment of the invention, the ground or sieved polymer may be subjected to a step of surface crosslinking. Herein, the surface crosslinking agent is not limited in terms of its construction as long as it can react with the functional group of the polymer. As examples of the surface crosslinking agent, polyhydric alcohol compounds, multivalent alkylene carbonate compounds, multivalent epoxy compounds, and the like may be mentioned.

The surface crosslinking agent may be included in the content of about <NUM> to <NUM> parts by weight, based on <NUM> parts by weight of the base polymer powder obtained from the ground or sieved polymer.

When the surface crosslinking agent is used, it may further include water and/or methanol.

The surface crosslinking step may be conducted by heating at a temperature of <NUM> to <NUM> for <NUM> to <NUM> minutes. Preferably, the base polymer powder to which the surface crosslinking solution is added may be heated at a maximum reaction temperature of <NUM> to <NUM>, or <NUM> to <NUM>, for <NUM> to <NUM> minutes, <NUM> to <NUM> minutes, or <NUM> to <NUM> minutes, thus progressing a surface crosslinking reaction. More specifically, the surface crosslinking step may be progressed by raising the temperature from the initial temperature of <NUM> to <NUM>, or <NUM> to <NUM>, to the maximum reaction temperature for <NUM> to <NUM> minutes, and maintaining the maximum temperature for <NUM> to <NUM> minutes, thus heat treating.

A temperature rise means for the surface crosslinking reaction is not specifically limited. A heating medium may be supplied, or a heat source may be directly supplied to heat it. Here, the kinds of the heating medium that can be used may include a temperature-increased fluid such as steam, hot air, hot oil, etc., but is not limited thereto, and the temperature of the heating medium supplied may be appropriately selected considering the means of the heating medium, temperature rise speed, and a temperature to be increased. Meanwhile, for the heat source directly supplied, electric heating, gas heating, etc., may be used, but is not limited thereto.

Thus, according to the present invention, a superabsorbent polymer composition further including a surface crosslink layer formed on the superabsorbent polymer particles may be provided.

The superabsorbent polymer particles obtained by the above process, the above-explained chelating agent, and the mixture of an organic salt and a silicate-based salt may be uniformly mixed to obtain the superabsorbent polymer composition of one embodiment of the present invention.

Herein, a method of mixing is not specifically limited, and for example, superabsorbent polymer particles, a chelating agent, an organic acid, and a silicate salt may be put into a reactor and mixed; a solution including a chelating agent, an organic acid, and a silicate salt may be sprayed to the superabsorbent polymer; a superabsorbent polymer, a chelating agent, an organic acid, and silicate salt particles may be continuously fed into a reactor such as a continuously operated mixer and mixed; or an organic acid and a silicate salt may be previously mixed, and then a superabsorbent polymer, a chelating agent, and the mixture of an organic acid and a silicate salt may be continuously fed and mixed.

Meanwhile, in the superabsorbent polymer composition of one embodiment, the superabsorbent polymer particles may further include residual iron ions derived from a monomer composition including water soluble ethylenically unsaturated monomers and/or an initiator, in the content of <NUM> ppmw or less, or <NUM> to <NUM> ppmw, based on the total monomers.

In the preparation process of superabsorbent polymer particles, a polymerization initiator such as a common redox initiator and the like may be used, and iron ions derived from the initiator may remain in the monomers and/or superabsorbent polymer particles. However, such iron ions may cause property deterioration of a superabsorbent polymer composition, but since the composition of one embodiment includes a chelating agent, the remaining amount of the iron ions may be reduced. As a result, the superabsorbent polymer composition of one embodiment may exhibit excellent properties.

Meanwhile, a method of preparing a superabsorbent polymer composition having an antimicrobial property may include steps of: mixing a certain amount of a chelating agent including EDTA or an alkali metal salt thereof; mixing an organic acid and a silicate-based salt and an agent for controlling a particle size to prepare an antimicrobial agent having a controlled particle size; and mixing superabsorbent polymer particles and the antimicrobial agent having a controlled particle size.

Herein, an apparatus for preparing the antimicrobial agent having a controlled particle size and antimicrobial superabsorbent polymer particles is not particularly limited in terms of its constructions and conditions, and they may be prepared through stirring using a common mixer (for example, a Ploughshare blender).

The superabsorbent polymer composition of one embodiment obtained as explained above may exhibit excellent antimicrobial/deodorizing effects and basic absorption properties.

Further, the final antimicrobial superabsorbent polymer composition to which an antimicrobial agent having a controlled particle size prepared by mixing the above-explained four components is added may be in the form of particles having an average particle size of <NUM> to <NUM>. That is, in the present invention, by significantly reducing the fine particles in the particle size distribution of an antimicrobial agent, the content of fine particles in the total superabsorbent polymer composition may also be reduced, and particularly, a particle size distribution of <NUM> to <NUM> may be increased. Particularly, an antimicrobial agent such as a chelating agent that is added to exhibit the antimicrobial property may become a direct cause of fine particles, but in the present invention, by adding an antimicrobial agent having a controlled particle size, the content of fine particles in the superabsorbent polymer composition may be significantly reduced, compared to the conventional antimicrobial agent of the same content.

Preferably, in the total particle size distribution of the superabsorbent polymer composition of the present invention, the rate of particles having an average particle size of <NUM> to <NUM> obtained by sieving may be <NUM> wt% or more, preferably <NUM> wt% or more. Herein, since the superabsorbent polymer composition basically includes fine particles of the superabsorbent polymer itself, when the antimicrobial agent is included, the fine particles of the superabsorbent polymer itself may also be included. More preferably, in the total particle size distribution of the superabsorbent polymer composition of the present invention, the rate of absorbent polymer powders having a particle size of less than <NUM> may be <NUM> wt% or less, and the rate of absorbent polymer powders having a particle size of <NUM> or more may be <NUM> wt% or <NUM> wt% or less. Herein, in the rate of the superabsorbent polymer powders having a particle size of less than <NUM>, the rate of the superabsorbent polymer powders having an average particle size of less than <NUM> may be <NUM> wt% or less, <NUM> wt% or less, or <NUM> wt%, and the rate of the superabsorbent polymer powders of <NUM> to <NUM> may be <NUM> wt% or less or <NUM> wt% or less. More preferably, in the average particle size distribution measured with a standard sieve, based on the total powder content, a) the rate of powders having an average particle size of <NUM> or more may be <NUM> wt% or less, b) the rate of powders having a particle size of <NUM> to <NUM> may be <NUM>~<NUM> wt%, c) the rate of powders having a particle size of <NUM> to <NUM> may be <NUM>~<NUM> wt%, d) the rate of powders having a particle size of <NUM> to <NUM> may be <NUM>~<NUM> wt%, e) the rate of powders having a particle size of <NUM> to <NUM> may be <NUM> wt% or less, and f) the rate of powders having a particle size of less than <NUM> may be <NUM> wt% or less.

Meanwhile, hygienic goods having excellent antimicrobial/deodorizing effects may be provided by a method having excellent processability and stability.

That is, provided are antimicrobial, deodorizing hygienic goods including the superabsorbent polymer composition. The hygienic goods include disposable absorption products, and preferably include diapers, which may be child diapers or adult diapers. The hygienic goods can improve a sense of use due to excellent antimicrobial and deodorizing properties as explained above, while maintaining basic absorption properties such as centrifugal retention capacity and absorption under pressure, and the like.

Hereinafter, the actions and the effects of the invention will be explained in more detail, through specific examples of the invention.

However, these examples are presented only as illustrations of the invention, and the scope of the right of the invention is not limited thereby.

<NUM> parts by weight of acrylic acid monomers were mixed with <NUM> parts by weight of caustic soda (NaOH) and <NUM> parts by weight of water, and to the mixture, <NUM> parts by weight of a thermal polymerization initiator of sodium persulfate, <NUM> parts by weight of a photopolymerization initiator of diphenyl(<NUM>,<NUM>,<NUM>-trimethylbenzoyl)phosphine oxide, and <NUM> parts by weight of a crosslinking agent of polyethylene glycol diacrylate were added to prepare a monomer composition.

While the monomer composition was flowed at the flow rate of <NUM>/h on a polymerization belt of a continuous belt polymerization reactor, of which internal temperature is maintained at <NUM>, and on top of which a UV irradiation device having intensity of <NUM> mW with a mercury UV lamp light source is installed, UV was irradiated for <NUM> minute, and a polymerization reaction was progressed for an additional <NUM> minutes without a light source.

A gel type of polymerization sheet emerging after the polymerization was finished was primarily cut using a shredder type of cutter, and then coarsely ground through a meat chopper. Thereafter, it was dried at <NUM> for <NUM> minutes through a hot air dryer, and then ground using a rotary mixer and sieved to <NUM> to <NUM>, thus preparing a base polymer.

Into the base polymer, <NUM> wt% of ethylene glycol diglycidyl epoxide were introduced and uniformly mixed, and then a surface treatment was progressed at <NUM> for <NUM> hour to obtain a superabsorbent polymer.

Based on <NUM> parts by weight of the superabsorbent polymer, i) <NUM> parts by weight of EDTA sodium salt (EDTA-2Na) and ii) <NUM> parts by weight of a mixture including <NUM> wt% of citric acid and <NUM> wt% of sodium metasilicate salt, and iii) based on <NUM> parts by weight of the mixture of i) and ii), <NUM> parts by weight of mineral oil, which is an agent for controlling a particle size, were put in a Ploughshare blender, followed by stirring at <NUM> rpm for <NUM> minutes. The prepared mixture of three components is referred to as an antimicrobial agent having a controlled particle size, and the particle size distribution of the antimicrobial agent is as follows.

That is, in the average particle size distribution measured with a standard sieve, based on the total powder content, a) the rate of powders having an average particle size of <NUM> or more was <NUM> wt%, b) the rate of powders having a particle size of <NUM> to <NUM> was <NUM> wt%, c) the rate of powders having a particle size of <NUM> to <NUM> was <NUM> wt%, d) the rate of powders having a particle size of <NUM> to <NUM> was <NUM> wt%, e) the rate of powders having a particle size of <NUM> to <NUM> was <NUM> wt%, and f) the rate of powders having a particle size of less than <NUM> was <NUM> wt%.

Electronic scale (precision: <NUM>), sieve shaker, sieve (<NUM>, <NUM>, <NUM>, <NUM>, <NUM> mesh standard sieve), pan receiver and cap, <NUM> mℓ beaker.

A pan receiver was placed on the lowest stage, and sieves were sequentially stacked thereon from the sieve having the smallest mesh size. <NUM> of the sample was quantitatively weighed in a <NUM> mℓ beaker, and then put in the highest stage sieve, and the lid was closed. The sieve apparatus was fixed in a sieve shaker, and shaken for <NUM> minutes. After shaking for <NUM> minutes, the samples remaining on each sieve wire mesh were collected and weighed. At this time, care was taken so that the samples were not spilled to the outside, and the measurement width was set up as <NUM>.

The rate remaining on the sieves was calculated by the following Equation <NUM>.

Particles of <NUM> mesh or larger, <NUM> to <NUM> mesh, <NUM> to <NUM> mesh, <NUM> to <NUM> mesh, <NUM> to <NUM> mesh, and <NUM> mesh or smaller were measured.

Herein, the particle sizes were reported in a data sheet to two decimal point, while the particle size of "<NUM> mesh or smaller" was rounded off to a significant figure.

Thereafter, <NUM> parts by weight of the superabsorbent polymer and <NUM> parts by weight of the antimicrobial agent having a controlled particle size were mixed, and the prepared superabsorbent polymer composition was referred to as Example <NUM>. Further, based on the total content of the superabsorbent polymer composition (superabsorbent polymer + antimicrobial agent having a controlled particle size), the rate of superabsorbent polymer particles of <NUM> to less than <NUM> was <NUM> wt% or more, the rate of superabsorbent polymer particles of <NUM> to less than <NUM> was <NUM> wt% or less, the rate of superabsorbent polymer particles of less than <NUM> was <NUM> wt%, and the rate of superabsorbent polymer particles of <NUM> or more was <NUM> wt% or less.

For the antimicrobial agent containing EDTA-2Na in the low content of <NUM> parts by weight, or <NUM> parts by weight, only a dust generation tendency according to an increase in the content of mineral oil was observed, and the antimicrobial efficiency was measured when the EDTA-2Na content was <NUM> part by weight (phr). The PSD of the final antimicrobial SAP was also measured only at that time.

A superabsorbent polymer was prepared by the same method as Example <NUM>.

Based on <NUM> parts by weight of the superabsorbent polymer, i) <NUM> parts by weight of EDTA sodium salt (EDTA-2Na) and ii) <NUM> parts by weight of a mixture including <NUM> wt% of citric acid and <NUM> wt% of sodium metasilicate salt, and iii) based on <NUM> parts by weight of the mixture of i) and ii), <NUM> parts by weight of mineral oil, which is an agent for controlling a particle size, were put in a Ploughshare blender, followed by stirring at <NUM> rpm for <NUM> minutes. The prepared mixture of three components is referred to as an antimicrobial agent having a controlled particle size, and the particle size distribution of the antimicrobial agent is the same as Example <NUM>.

Thereafter, <NUM> parts by weight of the superabsorbent polymer and <NUM> parts by weight of the antimicrobial agent having a controlled particle size were mixed, and the prepared superabsorbent polymer composition is referred to as Example <NUM>.

Based on <NUM> parts by weight of the superabsorbent polymer, i) <NUM> parts by weight of EDTA sodium salt (EDTA-2Na) and ii) <NUM> parts by weight of a mixture including <NUM> wt% of citric acid and <NUM> wt% of sodium metasilicate salt, and iii) based on <NUM> parts by weight of the mixture of i) and ii), <NUM> part by weight of mineral oil, which is an agent for controlling a particle size, were put in a Ploughshare blender, followed by stirring at <NUM> rpm for <NUM> minutes. The prepared mixture of three components is referred to as an antimicrobial agent having a controlled particle size. The particle size distribution of the antimicrobial agent is the same as Example <NUM>.

Based on <NUM> parts by weight of the superabsorbent polymer, i) <NUM> parts by weight of EDTA sodium salt (EDTA-2Na) and ii) <NUM> parts by weight of a mixture including <NUM> wt% of citric acid and <NUM> wt% of sodium metasilicate salt, and iii) based on <NUM> parts by weight of the mixture of i) and ii), <NUM> parts by weight of mineral oil, which is an agent for controlling a particle size, were put in a Ploughshare blender, followed by stirring at <NUM> rpm for <NUM> minutes. The prepared mixture of three components is referred to as an antimicrobial agent having a controlled particle size. The particle size distribution of the antimicrobial agent is the same as Example <NUM>.

Based on <NUM> parts by weight of the superabsorbent polymer, i) <NUM> parts by weight of EDTA sodium salt (EDTA-2Na) and ii) <NUM> parts by weight of a mixture including <NUM> wt% of citric acid and <NUM> wt% of sodium metasilicate salt, and iii) based on <NUM> parts by weight of the mixture of i) and ii), <NUM> parts by weight of mineral oil, which is an agent for controlling a particle size, were put in a Ploughshare blender, followed by stirring at <NUM> rpm for <NUM> minutes. The prepared mixture of three components is referred to as an antimicrobial agent having a controlled particle size. The particle size distribution of the antimicrobial agent is the same as Example <NUM>.

Based on <NUM> parts by weight of the superabsorbent polymer, i) <NUM> parts by weight of EDTA sodium salt (EDTA-2Na) and ii) <NUM> parts by weight of a mixture including <NUM> wt% of citric acid and <NUM> wt% of sodium metasilicate salt, and iii) based on <NUM> parts by weight of the mixture of i) and ii), <NUM> part by weight of mineral oil, which is an agent for controlling a particle size, were put in a Ploughshare blender, followed by stirring at <NUM> rpm for <NUM> minutes. The prepared mixture of three components is referred to as an antimicrobial agent having a controlled particle size. The particle size distribution of the antimicrobial agent is the same as Example <NUM>.

Based on <NUM> parts by weight of the superabsorbent polymer, i) <NUM> part by weight of EDTA sodium salt (EDTA-2Na) and ii) <NUM> parts by weight of a mixture including <NUM> wt% of citric acid and <NUM> wt% of sodium metasilicate salt, and iii) based on <NUM> parts by weight of the mixture of i) and ii), <NUM> parts by weight of mineral oil, which is an agent for controlling a particle size, were put in a Ploughshare blender, followed by stirring at <NUM> rpm for <NUM> minutes. The prepared mixture of three components is referred to as an antimicrobial agent having a controlled particle size. The particle size distribution of the antimicrobial agent is the same as Example <NUM>.

Based on <NUM> parts by weight of the superabsorbent polymer, i) <NUM> part by weight of EDTA sodium salt (EDTA-2Na) and ii) <NUM> parts by weight of a mixture including <NUM> wt% of citric acid and <NUM> wt% of sodium metasilicate salt, and iii) based on <NUM> parts by weight of the mixture of i) and ii), <NUM> parts by weight of mineral oil, which is an agent for controlling a particle size, were put in a Ploughshare blender, followed by stirring at <NUM> rpm for <NUM> minutes. The prepared mixture of three components is referred to as an antimicrobial agent having a controlled particle size. The particle size distribution of the antimicrobial agent is the same as Example <NUM>.

Based on <NUM> parts by weight of the superabsorbent polymer, i) <NUM> part by weight of EDTA sodium salt (EDTA-2Na) and ii) <NUM> parts by weight of a mixture including <NUM> wt% of citric acid and <NUM> wt% of sodium metasilicate salt, and iii) based on <NUM> parts by weight of the mixture of i) and ii), <NUM> part by weight of mineral oil, which is an agent for controlling a particle size, were put in a Ploughshare blender, followed by stirring at <NUM> rpm for <NUM> minutes. The prepared mixture of three components is referred to as an antimicrobial agent having a controlled particle size. The particle size distribution of the antimicrobial agent is the same as Example <NUM>.

Based on the total content of the antimicrobial superabsorbent polymer composition including an antimicrobial agent having a controlled particle size (superabsorbent polymer + antimicrobial agent having a controlled particle size), the rate of superabsorbent polymer particles of <NUM> to less than <NUM> was <NUM> wt% or more, the rate of superabsorbent polymer particles of <NUM> to less than <NUM> was <NUM> wt% or less, the rate of superabsorbent polymer particles of less than <NUM> was <NUM> wt%, and the rate of superabsorbent polymer particles of <NUM> or more was <NUM> wt% or less.

Based on <NUM> parts by weight of the superabsorbent polymer, i) <NUM> parts by weight of EDTA sodium salt (EDTA-2Na) and ii) <NUM> parts by weight of a mixture including <NUM> wt% of citric acid and <NUM> wt% of sodium metasilicate salt were put in a Ploughshare blender, followed by stirring at <NUM> rpm for <NUM> minutes.

Thereafter, <NUM> parts by weight of the superabsorbent polymer and <NUM> parts by weight of the mixture of two components as prepared above were mixed, and the prepared superabsorbent polymer composition is referred to as Comparative Example <NUM>.

The antimicrobial mixture without mineral oil had a particle size distribution wherein the rate of particles of <NUM> to less than <NUM> was <NUM> wt% or less, the rate of particles of <NUM> to less than <NUM> was <NUM>~<NUM> wt%, the rate of particles of less than <NUM> was <NUM>~<NUM> wt%, and the rate of particles of <NUM> or more was <NUM> wt% or less.

The antimicrobial mixture without mineral oil had the same particle size distribution as Comparative Example <NUM>.

Based on <NUM> parts by weight of the superabsorbent polymer, i) <NUM> part by weight of EDTA sodium salt (EDTA-2Na) and ii) <NUM> parts by weight of a mixture including <NUM> wt% of citric acid and <NUM> wt% of sodium metasilicate salt were put in a Ploughshare blender, followed by stirring at <NUM> rpm for <NUM> minutes.

Based on the total content of the antimicrobial superabsorbent polymer composition including an antimicrobial mixture of which particle size was not controlled (superabsorbent polymer + antimicrobial agent of which particle size was not controlled), the rate of superabsorbent polymer particles of <NUM> to less than <NUM> was <NUM> wt% or less, the rate of superabsorbent polymer particles of <NUM> to less than <NUM> was <NUM>~<NUM> wt%, the rate of superabsorbent polymer particles of less than <NUM> was <NUM>~<NUM> wt%, and the rate of superabsorbent polymer particles of <NUM> or more was <NUM> wt% or less.

i) <NUM> part by weight of EDTA sodium salt (EDTA-2Na) and ii) <NUM> parts by weight of a mixture including <NUM> wt% of citric acid and <NUM> wt% of sodium metasilicate salt were put in a Ploughshare blender, followed by stirring at <NUM> rpm for <NUM> minutes. The prepared mixture was used to as an antimicrobial agent, and is referred to as Reference Example <NUM>.

i) <NUM> parts by weight of EDTA sodium salt (EDTA-2Na) and ii) <NUM> parts by weight of a mixture including <NUM> wt% of citric acid and <NUM> wt% of sodium metasilicate salt were put in a Ploughshare blender, followed by stirring at <NUM> rpm for <NUM> minutes. The prepared mixture was used to as an antimicrobial agent, and is referred to as Reference Example <NUM>.

Both the antimicrobial mixture of Reference Examples <NUM> and <NUM> exhibited a) the rate of powders having a particle size of <NUM> or more of <NUM> wt% or less, b) the rate of powders having a particle size of <NUM> to <NUM> of <NUM>~<NUM> wt%, c) the rate of powders having a particle size of <NUM> to <NUM> of <NUM>-<NUM> wt%, d) the rate of powders having a particle size of <NUM> to <NUM> of <NUM>~<NUM> wt%, e) the rate of powders having a particle size of <NUM> to <NUM> of <NUM>~<NUM> wt%, and f) the rate of powders having a particle size of less than <NUM> of <NUM>~<NUM> wt%, based on the total powder content, in the average particle size distribution measured with a standard sieve.

The properties of the superabsorbent polymer compositions of Examples <NUM> to <NUM> and Comparative Examples <NUM> to <NUM> were measured as follows, and the results are shown in Tables <NUM> and <NUM>.

<NUM> of artificial urine inoculated with <NUM>,<NUM> CFU/ml of Proteus mirabillis (ATCC <NUM>) was incubated in an oven of <NUM> for <NUM> hours. The artificial urine and the artificial urine after incubation for <NUM> hours were referred to as controls, and were properly washed with <NUM> of a saline solution to measure CFUs (colony forming units), thereby calculating the properties of the controls.

Two grams of each of the superabsorbent polymer, and the superabsorbent polymer compositions of Example <NUM> to <NUM> and Comparative Examples <NUM> to <NUM>, were put into <NUM> of the artificial urine inoculated with <NUM>,<NUM> CFU/ml of Proteus mirabillis (ATCC <NUM>), followed by shaking for <NUM> minute to uniformly mix them. Thereafter, it was incubated in an oven of <NUM> for <NUM> hours. The artificial urine after incubation for <NUM> hours was properly washed with <NUM> of a saline solution to measure CFUs (colony forming units). Thereby, the antimicrobial/deodorizing properties of each example and comparative example were calculated/evaluated.

A DUST value was analyzed using Dustview II equipment (manufactured by Palas GmbH) capable of measuring the degree of dust of the superabsorbent polymer with a laser.

A dust number was measured using <NUM> of the SAP sample prepared in the examples or comparative examples, and since small particles and specific materials drop at lower speeds than bigger grains, a dust number was calculated by the following Equation <NUM>. <MAT> (In Equation <NUM>, Max value denotes the maximum dust value, and the <NUM> value denotes a value measured <NUM> seconds after reaching the maximum dust value.

The superabsorbent polymer prepared in the examples or comparative examples was properly mixed so that particles may be uniformly mixed, and then <NUM>±<NUM> of each sample was taken and poured into a <NUM> beaker. On the bottom of a funnel having the lowest stage diameter of <NUM> (unit), a cup for measuring density was positioned right at the center, and then the hole of the funnel was blocked and the metered sample was lightly poured into the funnel and filled. At the moment when the blocked hole of the funnel was opened, a stop watch was operated to measure a time (seconds) taken until the sample completely went down to the lowest stage part of the funnel. All the processes were progressed in a constant temperature and constant humidity chamber (temperature <NUM>±<NUM>, relative humidity <NUM>±<NUM> %).

<NUM> of each superabsorbent polymer was flowed through the orifice of an apparatus for measuring standard fluidity and received in a container having a volume of <NUM>, and the superabsorbent polymer was planed so as to become horizontal, thus controlling the volume of the superabsorbent polymer to <NUM>, and then the weight of the superabsorbent polymer excluding the container was measured. The weight of the superabsorbent polymer only was divided by the volume of the superabsorbent polymer, i.e., <NUM>, thereby calculating an apparent density corresponding to the weight of the superabsorbent polymer per unit volume.

Centrifugal retention capacity (CRC) by absorption rate under no load was measured according to European Disposables and Nonwovens Association (EDANA) Standard EDANA WSP <NUM>. W<NUM> (g, about <NUM>) of the superabsorbent polymer was uniformly put in an envelope made of a non-woven fabric and sealed, and then soaked in a saline solution (<NUM> wt% sodium chloride aqueous solution) at room temperature. After <NUM> minutes, the envelope was drained at <NUM> for <NUM> minutes using a centrifuge, and then the weight W<NUM> (g) of the envelope was measured. Further, the same operation was conducted without using a superabsorbent polymer, and then the weight W<NUM> (g) at that time was measured. Using the obtained weights, CRC (g/g) was calculated according to the following Equation <NUM>, thus confirming centrifugal retention capacity.

Referring to Tables <NUM> and <NUM>, it was confirmed that the superabsorbent polymer compositions of the examples exhibited improved antimicrobial/deodorizing properties while maintaining centrifugal retention capacity at least equivalent to the comparative examples, by adding a specific amount of an agent for controlling a particle size to functional additives. Particularly, it can be seen that the examples of the present invention can remarkably reduce a dust value generated during the process, compared to the comparative examples, and thus can provide an antimicrobial superabsorbent polymer composition fulfilling both stability and processability.

Herein, since a direct cause of dust in the antimicrobial mixture is EDTA-2Na, the higher content may cause a dust problem, and thus in the case of Comparative Examples <NUM> to <NUM>, when the content of EDTA-2Na was increased, a dust value increased.

Claim 1:
A superabsorbent polymer composition comprising:
superabsorbent polymer particles having a particle diameter of <NUM> to <NUM> as measured by sieving, comprising a crosslinked polymer of water-soluble ethylenically unsaturated monomers including acid groups, wherein at least a part of the acid groups are neutralized; and
an antimicrobial agent having a controlled particle size,
wherein the antimicrobial agent includes a chelating agent including EDTA or an alkali metal salt thereof, a mixture of an organic acid and a silicate-based salt, and an agent for controlling a particle size,
wherein the antimicrobial agent having a controlled particle size is included in a content of <NUM> to <NUM> parts by weight, based on <NUM> parts by weight of the superabsorbent polymer particles,
wherein the organic acid is included in a content of <NUM> to <NUM> wt%, based on a total weight of the mixture of the organic acid and the silicate-based salt,
wherein the agent for controlling a particle size is included in a content of <NUM> to <NUM> parts by weight, based on <NUM> parts by weight of a sum of the chelating agent, and the mixture of the organic acid and the silicate-based salt,
wherein the chelating agent is included in a content of <NUM> to <NUM> parts by weight, based on <NUM> parts by weight of the superabsorbent polymer particles, and
wherein the mixture of an organic acid and a silicate-based salt is included in the content of <NUM> to <NUM> parts by weight, based on <NUM> parts by weight of the superabsorbent polymer particles.