KR102623892B1 - Super absorbent polymer and preparation method thereof - Google Patents

Abstract

The present invention relates to a superabsorbent polymer that can exhibit improved bacterial growth inhibition properties without decreasing the physical properties of the superabsorbent polymer, such as water retention capacity and absorbency under pressure, or increasing dust generation, and a method for manufacturing the same. The superabsorbent polymer may include a base resin powder containing a cross-linked polymer of a water-soluble ethylenically unsaturated monomer containing an acidic group and at least a portion of the acidic group being neutralized; and a surface cross-linked layer formed on the base resin powder by further cross-linking the cross-linked polymer via a surface cross-linking agent, wherein the cross-linked polymer of the base resin powder or the surface cross-linked layer is an antibacterial agent containing an organic acid salt having an aromatic ring. is included within the cross-linked structure.

Description

Superabsorbent polymer and manufacturing method thereof {SUPER ABSORBENT POLYMER AND PREPARATION METHOD THEREOF}

This application claims the benefit of priority based on Korean Patent Application No. 10-2019-0121181, dated September 30, 2019, and all contents disclosed in the document of the Korean Patent Application are incorporated as part of this specification.

The present invention reduces the physical properties of superabsorbent polymers, such as water retention capacity and absorbency under pressure. It relates to a superabsorbent polymer that can exhibit improved bacterial growth inhibition properties without increasing dust generation and a method of manufacturing the same.

Super Absorbent Polymer (SAP) is a synthetic polymer material that has the ability to absorb moisture 500 to 1,000 times its own weight. Each developer produces SAM (Super Absorbency Material) and AGM (Absorbent Gel). They are named with different names, such as Material). The above-mentioned superabsorbent resins have begun to be commercialized as sanitary products, and are currently being used in sanitary products such as children's paper diapers, as well as soil repair agents for horticulture, water-stop materials for civil engineering and construction, sheets for seedlings, freshness maintainers in the food distribution field, and It is widely used in materials such as fomentation and electrical insulation.

However, these superabsorbent resins are most widely applied to sanitary products or disposable absorbent products such as paper diapers for children and adult diapers. Among these, when applied to adult diapers, secondary odor caused by bacterial growth causes a problem that causes great discomfort to consumers. To solve this problem, attempts have been made in the past to introduce various bacterial growth inhibitory ingredients or deodorizing or antibacterial functional ingredients into superabsorbent resins.

However, when introducing antibacterial agents that inhibit bacterial growth into the superabsorbent resin, the basic physical properties of the superabsorbent resin are lowered while exhibiting excellent bacterial growth inhibition and deodorizing properties, being harmless to the human body, and satisfying economic feasibility. It was not easy to select and introduce antibacterial ingredients that were not prescribed.

As an example, attempts have been made to introduce antibacterial agents containing antibacterial metal ions such as silver and copper, such as copper oxide, into superabsorbent polymers. These antibacterial metal ion-containing ingredients can destroy the cell walls of microorganisms such as bacteria and kill bacteria with enzymes that may cause bad odors in the superabsorbent polymer, giving it deodorizing properties. However, the metal ion-containing ingredients are classified as BIOCIDE substances that can kill even microorganisms beneficial to the human body. As a result, when applying the superabsorbent polymer to hygiene products such as diapers for children or adults, the introduction of the metal ion-containing antibacterial agent component is avoided as much as possible.

Meanwhile, in the past, when introducing antibacterial agents that inhibit bacterial growth into superabsorbent resins, a method of blending a small amount of the antibacterial agents into the superabsorbent resin was mainly applied. However, when applying this blending method, it is true that it was difficult to maintain the bacterial growth inhibition properties uniformly over time. Moreover, in the case of this blending method, uneven applicability and detachment of the antibacterial agent component may occur during the process of mixing the superabsorbent polymer and the antibacterial agent or using the superabsorbent polymer. As a result, there was a need to install new equipment for blending the antibacterial agent, and there were also disadvantages such as the generation of a large amount of dust during the use of the superabsorbent polymer.

Accordingly, without introducing metal ion-containing components, etc., the bacterial growth inhibition properties and deodorization properties are maintained uniformly for a long time, and the basic physical properties of the superabsorbent polymer are not reduced, and dust generation can be suppressed. The development of technology related to superabsorbent polymers is continuously being requested.

Accordingly, the present invention maintains excellent bacterial growth inhibition properties and deodorizing properties uniformly for a long time without introducing components harmful to the human body, and maintains excellent basic properties such as water retention capacity and pressure absorption capacity, and also increases dust generation. The object is to provide a superabsorbent polymer that suppresses and a method of manufacturing the same.

In addition, the present invention provides a sanitary product that includes the superabsorbent resin and exhibits excellent bacterial growth inhibition properties and deodorizing properties uniformly for a long period of time, while suppressing dust generation and maintaining excellent basic absorption properties.

The present invention provides a base resin powder comprising a cross-linked polymer of a water-soluble ethylenically unsaturated monomer containing an acidic group and at least a portion of the acidic group being neutralized; and

A surface cross-linking layer is formed on the base resin powder by additional cross-linking of the cross-linking polymer using a surface cross-linking agent,

The crosslinked polymer of the base resin powder or the surface crosslinked layer provides a superabsorbent resin containing an antibacterial agent containing an organic acid salt having an aromatic ring within the crosslinked structure.

The present invention also includes the steps of cross-polymerizing a water-soluble ethylenically unsaturated monomer containing an acidic group and at least a portion of the acidic group neutralized in the presence of an internal cross-linking agent to form a water-containing gel polymer;

Forming a base resin powder by drying, pulverizing and classifying the water-containing gel polymer; and

In the presence of a surface cross-linking agent, heat treating the base resin powder to further cross-link it,

The forming step of the hydrogel polymer or the additional crosslinking step provides a method for producing the superabsorbent polymer, which is performed in the additional presence of an antibacterial agent including an organic acid salt having an aromatic ring.

Additionally, the present invention provides sanitary products containing a superabsorbent polymer.

The superabsorbent resin of the present invention contains a specific antibacterial agent that does not contain metal ions, etc., and can exhibit excellent bacterial growth inhibition properties and deodorizing properties that selectively inhibit the growth of only bacteria that are harmful to the human body and cause secondary odor.

In addition, the superabsorbent resin is applied during cross-polymerization or surface cross-linking of the specific antibacterial agent to firmly fix it inside the cross-linked polymer or surface cross-linked layer forming the base resin powder, thereby providing excellent bacterial growth inhibition properties and deodorizing properties. can be displayed uniformly for a long time, and excellent water retention capacity and pressure absorption capacity can be maintained without deterioration of physical properties due to the addition of the antibacterial agent. In addition, by fixing this antibacterial agent within the cross-linked structure of the superabsorbent polymer, the disadvantage of generating a large amount of dust due to the addition of the antibacterial agent can also be solved.

Therefore, the superabsorbent polymer can be very preferably applied to various sanitary products such as adult diapers, where secondary odor is a particular problem.

The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as “comprise,” “comprise,” or “have” are intended to designate the presence of implemented features, steps, components, or a combination thereof, and are intended to indicate the presence of one or more other features or steps, It should be understood that the existence or addition possibility of components or combinations thereof is not excluded in advance.

Since the invention can be subject to various changes and can take various forms, specific embodiments will be illustrated and described in detail below. However, this is not intended to limit the invention to a specific disclosed form, and should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope of the invention.

Hereinafter, the superabsorbent polymer and its manufacturing method will be described in more detail according to specific embodiments of the invention.

The superabsorbent resin according to one embodiment of the invention includes a base resin powder containing a cross-linked polymer of a water-soluble ethylenically unsaturated monomer containing an acidic group and at least a portion of the acidic group being neutralized; and

A surface cross-linking layer is formed on the base resin powder by additional cross-linking of the cross-linking polymer using a surface cross-linking agent,

The cross-linked polymer of the base resin powder or the surface cross-linked layer contains an antibacterial agent containing an organic acid salt having an aromatic ring within the cross-linked structure.

The present inventors continued research on antibacterial agents that can be preferably applied to superabsorbent polymers instead of antibacterial agents containing antibacterial metal ions such as silver and copper. As a result of this continuous research, when an antibacterial agent component of an organic acid having an aromatic ring is introduced into a superabsorbent resin, it is possible to induce bad odors present in human skin without deteriorating the basic properties of the superabsorbent resin, such as water retention capacity and absorbency under pressure. It was confirmed that excellent bacterial growth inhibition properties and deodorizing properties that inhibit the growth of bacteria can be imparted to the superabsorbent resin.

In particular, for example, organic acid salts with an aromatic ring, such as sodium benzoate, are ingredients that are harmless to the human body and have guaranteed safety enough to be used in food or cosmetics, etc., and do not fall under BIOCIDE substances, and existing antibacterial agents containing metal ions are You can solve your problems.

Furthermore, the superabsorbent polymer of the above embodiment applies the antibacterial agent component of an organic acid salt having an aromatic ring during cross-polymerization or surface cross-linking, thereby firmly fixing it to the interior and surface of the cross-linking polymer or surface cross-linking layer constituting the base resin powder. Included in condition. Therefore, without separate equipment for blending, etc., the antibacterial agent component can be uniformly incorporated into the superabsorbent polymer without detachment, and the disadvantage of generating a large amount of dust during use of the superabsorbent polymer can also be suppressed.

Therefore, the superabsorbent polymer of one embodiment can uniformly exhibit the excellent bacterial growth inhibition properties and deodorizing properties for a long time, and can maintain excellent water retention capacity and absorbency under pressure without deterioration of physical properties due to the addition of the antibacterial agent. As a result, the superabsorbent polymer of the embodiment can be very preferably applied to various sanitary products such as adult diapers where secondary odor is a particular problem.

Meanwhile, in the superabsorbent polymer of the above embodiment, a metal salt of an organic acid having an aromatic ring may be used as the organic acid salt having an aromatic ring, and in consideration of its excellent bacterial growth inhibition properties, sodium of an organic acid having an aromatic ring may be used. (Na) salt or zinc (Zn) salt can be used. More specific examples of organic acid salts having such an aromatic ring include sodium benzoate or zinc benzoate.

The organic acid salt having the aromatic ring may be included in an amount of 0.1 to 5 parts by weight, or 0.3 to 4 parts by weight, or 0.4 to 3 parts by weight, based on 100 parts by weight of the base resin powder. If the content of the organic acid salt having the aromatic ring is too small, it is difficult to exhibit appropriate bacterial growth inhibition properties and deodorizing properties. Conversely, if the content is too large, basic physical properties such as water retention capacity of the superabsorbent polymer may be reduced.

In addition, the antibacterial agent included in the surface cross-linking layer may further include ethylenediaminetetraacetic acid (EDTA) or an alkali metal salt thereof in addition to the organic acid salt having an aromatic ring. These ingredients can suppress the metabolic activity of bacteria and other bacteria that cause secondary odor by chelating their nutrients. As a result, the superabsorbent resin further comprising this may exhibit improved bacterial growth inhibition properties and deodorizing properties.

The type of EDTA or its alkali metal salt is not particularly limited, and any component known to be added to the superabsorbent polymer as a chelating agent, for example, EDTA-2Na or EDTA-4Na, can be used.

The EDTA or its alkali metal salt may be included in an amount of 0.1 to 3 parts by weight, 0.3 to 2 parts by weight, or 0.4 to 1 part by weight, based on 100 parts by weight of the base resin powder. By additionally using EDTA or its alkali metal salt, the growth rate of bacteria causing bad odors can be further suppressed, thereby exhibiting excellent antibacterial and deodorizing properties. However, if the content of EDTA or its alkali metal salt is excessively large, it may cause a decrease in the absorption properties of the superabsorbent polymer, which is not desirable.

Meanwhile, the superabsorbent resin of the above-described embodiment has the structure of a typical superabsorbent resin, except that the antibacterial agent component is included in the internal crosslinked structure of the crosslinked polymer forming the base resin powder or the crosslinked structure of the surface crosslinked layer. You can have it. For example, the superabsorbent polymer may include a base resin powder containing a crosslinked polymer of a water-soluble ethylenically unsaturated monomer containing an acidic group and at least a portion of the acidic group being neutralized; and a surface cross-linking layer formed on the base resin powder by further cross-linking the cross-linking polymer via a surface cross-linking agent.

At this time, as the water-soluble ethylenically unsaturated monomer, any monomer commonly used in superabsorbent resins can be used without any particular restrictions. Here, any one or more monomers selected from the group consisting of anionic monomers and their salts, nonionic hydrophilic-containing monomers, amino group-containing unsaturated monomers, and quaternaries thereof can be used.

Specifically, (meth)acrylic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, 2-acryloylethane sulfonic acid, 2-methacryloylethane sulfonic acid, 2-(meth)acryloylpropane sulfonic acid or 2- (meth)acrylamide-2-methyl propane sulfonic acid anionic monomer and its salt; (meth)acrylamide, N-substituted (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate or polyethylene glycol ( Nonionic hydrophilic-containing monomer of meta)acrylate; and amino group-containing unsaturated monomers of (N,N)-dimethylaminoethyl (meth)acrylate or (N,N)-dimethylaminopropyl (meth)acrylamide and quaternaries thereof. You can.

More preferably, acrylic acid or its salt, for example, an alkali metal salt such as acrylic acid or its sodium salt, can be used. Using such a monomer, it is possible to produce a superabsorbent polymer with better physical properties. When using the alkali metal salt of acrylic acid as a monomer, acrylic acid can be at least partially neutralized with a basic compound such as caustic soda (NaOH).

Additionally, the base resin powder may be in the form of a fine powder containing a cross-linked polymer in which these monomers are cross-polymerized through an internal cross-linking agent.

The internal crosslinking agent includes a crosslinking agent having at least one functional group capable of reacting with a water-soluble substituent of the water-soluble ethylenically unsaturated monomer and at least one ethylenically unsaturated group; Alternatively, a crosslinking agent having two or more functional groups capable of reacting with the water-soluble substituent of the monomer and/or the water-soluble substituent formed by hydrolysis of the monomer may be used.

Specific examples of the internal crosslinking agent include bisacrylamide, bismethacrylamide, poly(meth)acrylate of polyol with 2 to 10 carbon atoms, or poly(meth)allyl ether of polyol with 2 to 10 carbon atoms, etc. Can be mentioned, more specifically, N,N'-methylenebis(meth)acrylate, ethyleneoxy(meth)acrylate, polyethyleneoxy(meth)acrylate, propyleneoxy(meth)acrylate, glycerin diacrylate. , glycerin triacrylate, trimethylol triacrylate, triallylamine, triallyl cyanurate, triallyl isocyanate, polyethylene glycol, diethylene glycol, and propylene glycol.

Additionally, the base resin powder may be in the form of a fine powder having a particle diameter of 150 to 850㎛.

Meanwhile, the superabsorbent polymer includes a surface cross-linked layer formed on the base resin powder by further cross-linking the cross-linked polymer of the base resin powder using a surface cross-linking agent.

Examples of such surface cross-linking agents include diol compounds, alkylene carbonate compounds, or polyvalent epoxy compounds, and more specific examples thereof include 1,3-propanediol, propylene glycol, 1,4-butanediol, and 1,6- Hexanediol, 1,2-hexanediol, 1,3-hexanediol, 2-methyl-1,3-propanediol, 2,5-hexanediol, 2-methyl-1,3-pentanediol, 2-methyl- Examples include diglycidyl ether compounds of alkylene glycols such as 2,4-pentanediol, tripropylene glycol, glycerol, ethylene carbonate, propylene carbonate, glycerol carbonate, or ethylene glycol diglycidyl ether. Any multivalent compound known to be usable as a surface crosslinking agent for superabsorbent polymers can be used without any restrictions.

The superabsorbent polymer of the above-described embodiment includes an antibacterial agent component, such as an organic acid salt having an aromatic ring, in, for example, an aqueous monomer solution or a surface cross-linking solution to form a cross-linked polymer or surface cross-linked layer of the base resin powder, The antibacterial agent component is included in a tightly physically or chemically fixed or bonded state inside or on the surface of the internal cross-linked structure of the cross-linked polymer or the additional cross-linked structure of the surface cross-linked layer. As a result, unlike conventional blending, uneven application, detachment, or separation of antibacterial ingredients does not occur, and the antibacterial ingredients are uniformly contained throughout, stably exhibiting excellent bacterial growth inhibition properties and deodorizing properties for a long period of time. You can. In addition, when using a superabsorbent polymer, the generation of dust derived from the antibacterial agent component can also be greatly reduced.

Such excellent bacterial growth inhibition properties are also demonstrated in the test examples described later, where the inhibition rate of bacteria (Esherichia Coli; ATCC25922) represented by the following formula 1 is as high as 75% or more, or 80% or more, or 90 to 100%. It can be supported from properties that have values:

[Equation 1]

Bacterial inhibition rate = [1- {CFU(12h)/ CFUcontrol(12h)}]*100 (%)

In Equation 1, CFU (12h) is the amount per unit volume of artificial urine of bacteria grown when the superabsorbent resin was added to artificial urine inoculated with Esherichia Coli (ATCC 25922) bacteria and cultured at 35°C for 12 hours. It represents the number of individuals (CFU/ml), and CFUcontrol (12h) is the number of individuals per unit volume of artificial urine (CFU) of the bacteria grown when the artificial urine inoculated with the bacteria was cultured under the same conditions without adding the superabsorbent resin. /ml).

In addition, the superabsorbent polymer can exhibit excellent dust suppression properties, and as proven in the test examples described later, the dust number calculated according to Equation 2 below is from the results measured with a laser dust meter. It can be supported from properties with low values of 1 to 5, or 1.2 to 3.5, or 1.5 to 2.5:

[Equation 2]

Dust number = Max value + 30 sec. value

In Equation 2, Max value represents the measured value when DUST is maximum when dropping the superabsorbent polymer into the laser dust meter inlet, and is measured at 30 sec. The value represents the measured value for 30 seconds after the Max value appears.

Meanwhile, the superabsorbent polymer of the above-described embodiment is obtained by thermally or photopolymerizing a monomer composition containing a water-soluble ethylenically unsaturated monomer and a polymerization initiator, and drying, pulverizing, classifying, and surface crosslinking the hydrogel polymer. It can be obtained, and if necessary, a differential reassembly process, etc. can be further performed.

More specifically, the method for producing the superabsorbent polymer includes the steps of cross-polymerizing a water-soluble ethylenically unsaturated monomer containing an acidic group and at least a portion of the acidic group neutralized in the presence of an internal cross-linking agent to form a water-containing gel polymer;

Forming a base resin powder by drying, pulverizing and classifying the water-containing gel polymer; and

In the presence of a surface cross-linking agent, heat treating the base resin powder to further cross-link it,

The forming step of the hydrogel polymer or the additional crosslinking step may be performed in the additional presence of an antibacterial agent including an organic acid salt having an aromatic ring.

In a specific example, in the step of forming the water-soluble gel polymer, cross-linking polymerization may be performed on an aqueous monomer solution containing the water-soluble ethylenically unsaturated monomer, a polymerization initiator, an internal cross-linking agent, and the antibacterial agent. As a result, a superabsorbent polymer of one embodiment in which the antibacterial agent is included in the crosslinked structure of the crosslinked polymer forming the base resin powder can be obtained.

In another specific example, the additional crosslinking step may be performed using a surface crosslinking solution containing the surface crosslinking agent and an antibacterial agent including an organic acid salt having an aromatic ring. As a result, a superabsorbent polymer of one embodiment in which the antibacterial agent is included in the additional crosslinking structure of the surface crosslinking layer can be obtained.

In this way, in the cross-linking polymerization step for forming the hydrogel polymer and base resin powder, or in the additional cross-linking step for forming the surface cross-linking layer, the manufacturing process of the superabsorbent resin is carried out by including an antibacterial agent component in the monomer aqueous solution or surface cross-linking solution. Accordingly, the antibacterial agent component can be introduced into the superabsorbent resin through the existing superabsorbent resin manufacturing process without additional equipment for blending, etc. Furthermore, as already mentioned above, the antibacterial agent component is firmly fixed within the surface cross-linked layer to prevent its detachment or uneven application, and the superabsorbent resin provides excellent and uniform bacterial growth inhibition and deodorizing properties for a long time. can be maintained. In addition, the problem of dust being generated due to the antibacterial agent component during use of the superabsorbent polymer can also be suppressed.

Meanwhile, the types of each component that can be used in the above manufacturing method, that is, monomers, internal cross-linking agents, surface cross-linking agents, and antibacterial agents, have already been described in detail for the superabsorbent polymer of one embodiment, and further description thereof will be omitted.

Additionally, the usage amount of each antibacterial agent component used in the above production method may also correspond to the content of each antibacterial agent component already described above. However, when the antibacterial agent component is used during cross-linking polymerization, it is used in the content range described above based on 100 parts by weight of the water-soluble ethylenically unsaturated monomer, and in the final manufactured superabsorbent resin, the same applies to 100 parts by weight of the base resin powder. It can be adjusted to include an equivalent content range.

Hereinafter, further description of the content range of the antibacterial agent will be omitted, and the description will focus on the manufacturing process of the superabsorbent polymer.

In the method for producing the superabsorbent polymer, first, a water-soluble ethylenically unsaturated monomer in which at least a portion of the acidic group has been neutralized is cross-polymerized in the presence of an internal cross-linking agent to form a water-soluble gel polymer. For this purpose, an aqueous monomer solution containing the monomer, a polymerization initiator, an internal cross-linking agent, and an aqueous solvent may be used. Additionally, the aqueous monomer solution may further include the antibacterial agent described above.

At this time, as the polymerization initiator, any initiator commonly used in the production of superabsorbent polymers can be used without any restrictions.

Specifically, the polymerization initiator may be a thermal polymerization initiator or a photopolymerization initiator based on UV irradiation, depending on the polymerization method. However, even with the photopolymerization method, a certain amount of heat is generated by irradiation such as ultraviolet rays, and a certain amount of heat is also generated as the polymerization reaction, which is an exothermic reaction, progresses, so a thermal polymerization initiator may be additionally included. The photopolymerization initiator can be used without limitation in composition as long as it is a compound that can form radicals by light such as ultraviolet rays.

Examples of the photopolymerization initiator include benzoin ether, dialkyl acetophenone, hydroxyl alkylketone, phenyl glyoxylate, and benzyl dimethyl ketal. Ketal), acyl phosphine, and alpha-aminoketone (α-aminoketone) can be used. Meanwhile, specific examples of acylphosphine include diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide, and ethyl (2,4,6- Trimethylbenzoyl)phenylphosphineate, etc. can be mentioned. More diverse photoinitiators are well described in Reinhold Schwalm's book "UV Coatings: Basics, Recent Developments and New Application (Elsevier 2007)" p115, and are not limited to the above-mentioned examples.

The photopolymerization initiator may be included at a concentration of 0.0001 to 2.0% by weight based on the aqueous monomer solution. If the concentration of the photopolymerization initiator is too low, the polymerization rate may be slow, and if the concentration of the photopolymerization initiator is too high, the molecular weight of the superabsorbent polymer may be small and the physical properties may become non-uniform.

Additionally, the thermal polymerization initiator may be one or more selected from the group of initiators consisting of persulfate-based initiator, azo-based initiator, hydrogen peroxide, and ascorbic acid. Specifically, examples of persulfate-based initiators include sodium persulfate (Na ₂ S ₂ O ₈ ), potassium persulfate (K ₂ S ₂ O ₈ ), and ammonium persulfate (NH ₄ ). ₂ S ₂ O ₈ ), etc., and examples of azo-based initiators include 2,2-azobis(2-amidinopropane) dihydrochloride, 2 ,2-azobis-(N,N-dimethylene)isobutyramidine dihydrochloride (2,2-azobis-(N,N-dimethylene)isobutyramidine dihydrochloride), 2-(carbamoylazo)isobutyronitrile (2-(carbamoylazo)isobutylonitril), 2,2-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (2,2-azobis[2-(2-imidazolin-2- yl)propane] dihydrochloride), 4,4-azobis-(4-cyanovaleric acid), etc. A variety of thermal polymerization initiators are well described in Odian's book 'Principle of Polymerization (Wiley, 1981)', p203, and are not limited to the above-mentioned examples.

The thermal polymerization initiator may be included at a concentration of 0.001 to 2.0% by weight based on the aqueous monomer solution. If the concentration of the thermal polymerization initiator is too low, no additional thermal polymerization occurs, so the effect of adding the thermal polymerization initiator may be minimal. If the concentration of the thermal polymerization initiator is too high, the molecular weight of the superabsorbent polymer may be small and the physical properties may become non-uniform. there is.

When these photo-polymerization initiators and thermal-polymerization initiators are used together, the thermal-polymerization initiator may be added to the monomer aqueous solution last just before the start of polymerization. At this time, the aqueous solution of the above-described antibacterial agent may be mixed with the thermal polymerization initiator and added to the aqueous monomer solution.

In addition, in the above manufacturing method, the monomer aqueous solution of the superabsorbent polymer may further include additives such as a thickener, a plasticizer, a storage stabilizer, and an antioxidant, if necessary.

Meanwhile, the method of forming a water-containing gel polymer by thermally polymerizing or photopolymerizing such an aqueous monomer solution is also a commonly used polymerization method, and there is no particular limitation in composition.

Specifically, polymerization methods are largely divided into thermal polymerization and light polymerization depending on the polymerization energy source. In general, when thermal polymerization is performed, it can be performed in a reactor with a stirring axis such as a kneader, and when light polymerization is performed, it can be carried out in a movable reactor. It may be carried out in a reactor equipped with a conveyor belt, but the above-described polymerization method is an example, and the invention is not limited to the above-described polymerization method.

At this time, the normal moisture content of the hydrogel polymer obtained by this method may be about 40 to about 80% by weight. Meanwhile, throughout this specification, “moisture content” refers to the content of moisture relative to the total weight of the hydrogel polymer, which is calculated by subtracting the weight of the polymer in a dry state from the weight of the hydrogel polymer. Specifically, it is defined as a value calculated by measuring the weight loss due to moisture evaporation from the polymer during the drying process by raising the temperature of the polymer through infrared heating. At this time, the drying conditions are to increase the temperature from room temperature to about 180°C and then maintain it at 180°C. The total drying time is set to 20 minutes, including 5 minutes for the temperature increase step, and the moisture content is measured.

Next, the obtained water-containing gel polymer is dried.

At this time, if necessary, a coarse grinding step may be further performed before drying to increase the efficiency of the drying step.

At this time, the pulverizer used is not limited in composition, but specifically, vertical pulverizer, turbo cutter, turbo grinder, rotary cutter mill, cutting. Includes any one selected from the group of shredding machines consisting of a cutter mill, a disc mill, a shred crusher, a crusher, a chopper, and a disc cutter. It can be done, but it is not limited to the above-described example.

At this time, in the coarse grinding step, the hydrogel polymer can be pulverized so that the particle size is about 2 to about 10 mm.

Drying is performed on the water-containing gel polymer that is coarsely pulverized as described above or immediately after polymerization without going through the coarse pulverization step.

The drying method of the drying step may also be selected and used without limitation in composition as long as it is a commonly used drying process for hydrogel polymers. Specifically, the drying step can be performed by methods such as hot air supply, infrared irradiation, microwave irradiation, or ultraviolet irradiation. The moisture content of the polymer after this drying step may be 0.1 to 10% by weight.

Next, the dried polymer obtained through this drying step is pulverized.

The polymer powder obtained after the grinding step may have a particle diameter of about 150 to about 850 μm. The grinder used for grinding to such particle size is specifically a pin mill, hammer mill, screw mill, roll mill, disc mill or jog. A jog mill, etc. may be used, but the invention is not limited to the above-described examples.

In addition, in order to manage the physical properties of the superabsorbent polymer powder that is finalized after the grinding step, a separate process may be performed to classify the polymer powder obtained after grinding according to particle size. Preferably, polymers having a particle diameter of 150 to 850 ㎛ are classified.

According to one embodiment of the invention, a step of surface crosslinking the pulverized or classified polymer may be further performed.

The above step is a step of performing additional crosslinking using a surface crosslinking agent to increase the surface crosslinking density of the base resin powder and forming a surface crosslinking layer, in which the unsaturated bonds of the water-soluble ethylenically unsaturated monomer remaining on the surface without crosslinking are formed. By additional crosslinking using a surface crosslinking agent, a superabsorbent polymer with increased surface crosslinking density is formed. This heat treatment process increases the surface cross-link density, that is, the external cross-link density, while the internal cross-link density does not change, so the superabsorbent polymer with the manufactured surface cross-link layer has a structure with a higher cross-link density on the outside than on the inside.

In this surface cross-linking step, as already described above, a surface cross-linking solution containing the surface cross-linking agent, an antibacterial agent including an organic acid salt having an aromatic ring and optionally EDTA or an alkali metal salt thereof, and a water solvent may be used.

The surface cross-linking agent may be used in an amount of 0.001 to 2 parts by weight based on 100 parts by weight of the base resin powder. For example, the surface cross-linking agent may be used in an amount of 0.005 parts by weight or more, 0.01 parts by weight or more, or 0.02 parts by weight or more, and 1.5 parts by weight or less, or 1 part by weight or less, based on 100 parts by weight of the base resin powder. By adjusting the content range of the surface cross-linking agent to the above-mentioned range, a superabsorbent polymer that exhibits various physical properties such as excellent absorption performance and liquid permeability can be manufactured.

Additionally, there is no limitation on the method of mixing the surface cross-linking liquid with the base resin powder. For example, mixing the surface cross-linking solution and the base resin powder in a reaction tank, spraying the surface cross-linking solution on the base resin powder, or continuously supplying the base resin powder and the surface cross-linking solution to a continuously operating mixer and mixing them. You can use this method, etc.

내지 약 250

의 온도에서 수행될 수 있다. 보다 구체적으로, 상기 표면 가교 공정은 약 100℃ 내지 약 220℃, 또는 약 120℃ 내지 약 200℃의 온도에서, 약 20 분 내지 약 2 시간, 또는 약 40 분 내지 약 80 분 동안 수행될 수 있다. 상술한 표면 가교 공정 조건의 충족 시 베이스 수지 분말의 표면이 충분히 가교되어 가압 흡수능이나 통액성이 증가될 수 있다. The surface crosslinking process takes about 80

to about 250

It can be performed at a temperature of More specifically, the surface crosslinking process may be performed at a temperature of about 100°C to about 220°C, or about 120°C to about 200°C, for about 20 minutes to about 2 hours, or about 40 minutes to about 80 minutes. . When the above-mentioned surface cross-linking process conditions are met, the surface of the base resin powder is sufficiently cross-linked to increase pressure absorbency or liquid permeability.

The temperature raising means for the surface crosslinking reaction is not particularly limited. Heating can be done 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 steam, hot air, or a heated fluid such as hot oil, but is not limited to this, and the temperature of the supplied heat medium depends on the means of the heat medium, the temperature increase rate, and the temperature increase target temperature. You can choose appropriately by taking this into consideration. Meanwhile, heat sources that are directly supplied include heating through electricity and heating through gas, but are not limited to the above-mentioned examples.

Meanwhile, by proceeding with the surface cross-linking process through the process described above as an example, a superabsorbent polymer can be manufactured and provided. This superabsorbent resin contains the above-mentioned specific antibacterial agent component in a tightly fixed state in the surface cross-linked layer, so it can exhibit excellent bacterial growth inhibition properties and deodorizing properties, and can also maintain excellent basic absorption properties.

Accordingly, these superabsorbent resins can be preferably included and used in various sanitary products, such as children's paper diapers, adult diapers, or sanitary napkins. In particular, adult diapers where secondary odor due to bacterial growth is a particular problem. It can be applied very preferably.

These sanitary products may follow the structure of conventional sanitary products except that the absorbent material includes the superabsorbent resin of one embodiment.

Hereinafter, the operation and effects of the invention will be described in more detail through specific examples of the invention. However, these examples are merely presented as examples of the invention, and the scope of the invention is not determined by them.

<Example>

Examples and Comparative Examples: Preparation of superabsorbent polymer

Comparative Example 1:

In a 3 L glass container equipped with a stirrer and thermometer, 484 g of acrylic acid, 2100 ppmw of polyethylene glycol diacrylate (PEGDA 400, Mw=400) as an internal cross-linker, and diphenyl (2,4,6-trimethylbenzoyl)-phos as a photoinitiator. After adding and dissolving 80 ppmw of pin oxide, 643 g of sodium hydroxide solution with a concentration of 31.5% by weight was added to prepare a water-soluble unsaturated monomer aqueous solution (degree of neutralization: 70 mol%; solid content: 45.8% by weight).

When the temperature of the water-soluble unsaturated monomer aqueous solution rises due to the heat of neutralization and reaches 40°C, the mixed solution is placed in a container containing 2400 ppmw of sodium persulfate (SPS), a thermal polymerization initiator, and then irradiated with ultraviolet light for 1 minute ( UV polymerization was performed at an irradiation dose of 10 mV/cm ² ) and aging was performed by heating in an oven at 80° C. for 120 seconds to obtain a water-containing gel polymer sheet.

The obtained hydrogel polymer sheet was passed through a chopper with a hole size of 16 mm to prepare crumbs. The crumb was dried in an oven capable of moving the air volume up and down. It was dried uniformly by flowing hot air at 185°C from bottom to top for 15 minutes and from top to bottom for 15 minutes. After drying, the water content of the dried product was ensured to be less than 2% by weight. After going through this drying process, it was classified using a standard mesh sieve of ASTM standards to obtain base resin powder having a particle size of 150 to 850 ㎛.

Meanwhile, for surface crosslinking (additional crosslinking) to the base resin powder, a surface containing 4.1 parts by weight of water, 0.5 parts by weight of propylene glycol, and 0.2 parts by weight of 1,3-propanediol, based on 100 parts by weight of the base resin powder. A crosslinking solution was mixed and prepared. For 100 parts by weight of the base resin, the surface cross-linking solution was sprayed using a paddle type mixer at 1000 rpm. Afterwards, surface crosslinking was performed by heat treatment at a temperature of 175 to 190°C for 65 minutes, and the superabsorbent polymer of Comparative Example 1 was prepared.

Comparative Example 2:

A superabsorbent polymer was prepared by proceeding with surface crosslinking in the same manner as in Comparative Example 1. The superabsorbent polymer composition of Comparative Example 2 was prepared by dry blending 2 parts by weight of sodium benzoate with 100 parts by weight of this superabsorbent polymer using a plow share mixer.

Comparative Example 3:

A superabsorbent polymer was prepared by proceeding with surface crosslinking in the same manner as in Comparative Example 1. The superabsorbent polymer composition of Comparative Example 3 was prepared by dry blending 0.5 parts by weight of sodium benzoate and 0.5 parts by weight of EDTA-4Na with 100 parts by weight of the superabsorbent polymer using a plow share mixer.

Example 1:

Base resin powder was prepared in the same manner as Comparative Example 1.

Based on 100 parts by weight of the base resin powder, a surface cross-linking solution containing 4.1 parts by weight of water, 0.5 parts by weight of propylene glycol, 0.2 parts by weight of 1,3-propanediol, and 2 parts by weight of sodium benzoate was mixed and prepared. For 100 parts by weight of the base resin, the surface cross-linking solution was sprayed using a paddle type mixer at 1000 rpm. Afterwards, surface crosslinking was performed by heat treatment at a temperature of 175 to 190°C for 65 minutes, and the superabsorbent polymer of Example 1 was prepared.

Example 2:

Base resin powder was prepared in the same manner as Comparative Example 1.

Based on 100 parts by weight of the base resin powder, a surface cross-linking solution containing 4.1 parts by weight of water, 0.5 parts by weight of propylene glycol, 0.2 parts by weight of 1,3-propanediol, 0.5 parts by weight of sodium benzoate, and 0.5 parts by weight of EDTA-4Na. Mixed and prepared. For 100 parts by weight of the base resin, the surface cross-linking solution was sprayed using a paddle type mixer at 1000 rpm. Afterwards, surface crosslinking was performed by heat treatment at a temperature of 175 to 190°C for 65 minutes, and the superabsorbent polymer of Example 2 was prepared.

Example 3:

Base resin powder was prepared in the same manner as Comparative Example 1.

Based on 100 parts by weight of the base resin powder, a surface cross-linking solution containing 4.4 parts by weight of water, 0.32 parts by weight of ethylene carbonate, 0.32 parts by weight of propylene carbonate, and 2 parts by weight of sodium benzoate was mixed and prepared. For 100 parts by weight of the base resin, the surface cross-linking solution was sprayed using a paddle type mixer at 1000 rpm. Afterwards, surface crosslinking was performed by heat treatment at a temperature of 175 to 190°C for 65 minutes, and the superabsorbent polymer of Example 3 was prepared.

Example 4:

Base resin powder was prepared in the same manner as Comparative Example 1.

Based on 100 parts by weight of the base resin powder, mix and prepare a surface cross-linking solution containing 4.4 parts by weight of water, 0.32 parts by weight of ethylene carbonate, 0.32 parts by weight of propylene carbonate, 0.5 parts by weight of sodium benzoate, and 0.5 parts by weight of EDTA-4Na. did. For 100 parts by weight of the base resin, the surface cross-linking solution was sprayed using a paddle type mixer at 1000 rpm. Afterwards, surface crosslinking was performed by heat treatment at a temperature of 175 to 190°C for 65 minutes, and the superabsorbent polymer of Example 4 was prepared.

Example 5:

In a 3 L glass container equipped with a stirrer and thermometer, 484 g of acrylic acid, 2100 ppmw of polyethylene glycol diacrylate (PEGDA 400, Mw=400) as an internal cross-linker, and diphenyl (2,4,6-trimethylbenzoyl)-phos as a photoinitiator. After adding and dissolving 80 ppmw of pin oxide, 643 g of sodium hydroxide solution with a concentration of 31.5% by weight was added to prepare a water-soluble unsaturated monomer aqueous solution (degree of neutralization: 70 mol%; solid content: 45.8% by weight).

When the temperature of the water-soluble unsaturated monomer aqueous solution rises to 40° C. due to the heat of neutralization, this mixture is mixed with 2400 ppmw of sodium persulfate (SPS), a thermal polymerization initiator, and 51.6 g of sodium benzoate (20% by weight aqueous solution) (sodium). Benzoate: 2 parts by weight based on 100 parts by weight of acrylic acid) was placed in a container containing a premixed solution, UV polymerization was performed by irradiating ultraviolet rays for 1 minute (irradiation amount: 10 mV/cm ² ), and placed in an oven at 80°C. Aging was performed by applying heat for 120 seconds to obtain a water-containing gel polymer sheet.

The obtained hydrogel polymer sheet was passed through a chopper with a hole size of 16 mm to prepare crumbs. The crumb was dried in an oven capable of moving the air volume up and down. It was dried uniformly by flowing hot air at 185°C from bottom to top for 15 minutes and from top to bottom for 15 minutes. After drying, the water content of the dried product was ensured to be less than 2% by weight. After going through this drying process, it was classified using a standard mesh sieve of ASTM standards to obtain base resin powder having a particle size of 150 to 850 ㎛.

Meanwhile, for surface crosslinking (additional crosslinking) to the base resin powder, a surface containing 4.1 parts by weight of water, 0.5 parts by weight of propylene glycol, and 0.2 parts by weight of 1,3-propanediol, based on 100 parts by weight of the base resin powder. A crosslinking solution was mixed and prepared. For 100 parts by weight of the base resin, the surface cross-linking solution was sprayed using a paddle type mixer at 1000 rpm. Afterwards, surface crosslinking was performed by heat treatment at a temperature of 175 to 190°C for 65 minutes, and the superabsorbent polymer of Example 5 was prepared.

Example 6:

In a 3 L glass container equipped with a stirrer and thermometer, 484 g of acrylic acid, 2100 ppmw of polyethylene glycol diacrylate (PEGDA 400, Mw=400) as an internal cross-linker, and diphenyl (2,4,6-trimethylbenzoyl)-phos as a photoinitiator. After adding and dissolving 80 ppmw of pin oxide, 643 g of sodium hydroxide solution with a concentration of 31.5% by weight was added to prepare a water-soluble unsaturated monomer aqueous solution (degree of neutralization: 70 mol%; solid content: 45.8% by weight).

When the temperature of the water-soluble unsaturated monomer aqueous solution rises to 40° C. due to the heat of neutralization, this mixed solution is mixed with 2400 ppmw of sodium persulfate (SPS), a thermal polymerization initiator, and 13 g of sodium benzoate (20% by weight aqueous solution) (100 g of acrylic acid). 0.5 parts by weight) and 13 g of EDTA-4Na dehydrate (20 wt% aqueous solution) (0.5 parts by weight based on 100 parts by weight of acrylic acid) were placed in a container containing a premixed solution and irradiated with ultraviolet rays for 1 minute (irradiation amount: UV polymerization was performed at 10 mV/cm ² ) and aged by applying heat for 120 seconds in an oven at 80° C. to obtain a water-containing gel polymer sheet.

The obtained hydrogel polymer sheet was passed through a chopper with a hole size of 16 mm to prepare crumbs. The crumb was dried in an oven capable of moving the air volume up and down. It was dried uniformly by flowing hot air at 185°C from bottom to top for 15 minutes and from top to bottom for 15 minutes. After drying, the water content of the dried product was ensured to be less than 2% by weight. After going through this drying process, it was classified using a standard mesh sieve of ASTM standards to obtain base resin powder having a particle size of 150 to 850 ㎛.

Meanwhile, for surface crosslinking (additional crosslinking) to the base resin powder, a surface containing 4.1 parts by weight of water, 0.5 parts by weight of propylene glycol, and 0.2 parts by weight of 1,3-propanediol, based on 100 parts by weight of the base resin powder. A crosslinking solution was mixed and prepared. For 100 parts by weight of the base resin, the surface cross-linking solution was sprayed using a paddle type mixer at 1000 rpm. Afterwards, surface crosslinking was performed by heat treatment at a temperature of 175 to 190°C for 65 minutes, and the superabsorbent polymer of Example 6 was prepared.

Evaluation of superabsorbent polymer physical properties

The physical properties of the superabsorbent polymer compositions of Examples 1 to 6 and Comparative Examples 1 to 3 were measured by the following method, and the results are shown in Table 1.

(1) Bacterial growth inhibition performance test

50ml of artificial urine inoculated with 2500 CFU/ml of Esherichia Coli (ATCC 25922) was cultured in an oven at 35°C for 12 hours. This artificial urine and the artificial urine after culturing for 12 hours were used as a control group, washed well with 150 ml of saline water, and CFU (Colony Forming Unit; CFU/ml) was measured and calculated as the physical properties of the control group.

2 g of the superabsorbent polymer of the Example or Comparative Example was added to 50 ml of artificial urine inoculated with 2500 CFU/ml of Esherichia Coli (ATCC 25922), and mixed evenly by shaking for 1 minute. It was cultured in an oven at 35°C for 12 hours. After culturing for 12 hours, the artificial urine was washed well with 150 ml of saline and the CFU (Colony Forming Unit; CFU/ml) was measured.

Each of these measurement results was calculated as a bacterial (Esherichia Coli; ATCC25922) growth rate represented by the following formula 1, and based on this, the bacterial growth inhibition characteristics of each Example and Comparative Example were evaluated:

[Equation 1]

Bacterial inhibition rate = [1- {CFU(12h)/ CFUcontrol(12h)}]*100 (%)

In Equation 1, CFU (12h) is the amount per unit volume of artificial urine of bacteria grown when the superabsorbent resin was added to artificial urine inoculated with Esherichia Coli (ATCC 25922) bacteria and cultured at 35°C for 12 hours. It represents the number of individuals (CFU/ml), and CFUcontrol (12h) is the number of individuals per unit volume of artificial urine (CFU) of the bacteria grown when the artificial urine inoculated with the bacteria was cultured under the same conditions without adding the superabsorbent resin. /ml), that is, represents the number of bacteria per unit volume of artificial urine (CFU/ml) measured for the control condition.

(2) Dust number

The dust level of the superabsorbent polymer was analyzed using Dustview II (manufactured by Palas GmbH), which can measure the dust level with a laser. Dust number was measured using 30 g of SAP sample. Because small particles and certain substances fall at a slower rate than coarse particles, the dust number was determined by the value calculated according to Equation 2 below:

[Equation 2]

Dust number = Max value + 30 sec. value

In Equation 2, Max value represents the measured value when DUST is maximum when dropping the superabsorbent polymer into the laser dust meter inlet, and is measured at 30 sec. The value represents the measured value for 30 seconds after the Max value appears.

(3) Centrifugal Retention Capacity (CRC)

According to the European Disposables and Nonwovens Association (EDANA) standard EDANA WSP 241.2, the water retention capacity of the absorbent resin was measured by absorbency under no load. Superabsorbent polymer W ₀ (g, approximately 0.2 g) was uniformly placed in a non-woven bag and sealed, and then immersed in 0.9% by weight physiological saline solution at room temperature. After 30 minutes, the bag was centrifuged, drained at 250G for 3 minutes, and the mass W ₂ (g) of the bag was measured. In addition, after performing the same operation without using resin, the mass W ₁ (g) at that time was measured.

Using each mass obtained in this way, CRC (g/g) was calculated according to the following equation 1 to confirm water retention capacity.

[Calculation Formula 1]

CRC(g/g) = {[W ₂ (g) - W ₁ (g)]/W ₀ (g)} - 1

In equation 1 above,

W ₀ (g) is the weight of the absorbent polymer (g),

W ₁ (g) is the weight of the device measured after dehydration at 250G for 3 minutes using a centrifuge without using absorbent resin,

W ₂ (g) is the weight of the device measured including the absorbent resin after immersing the absorbent resin in 0.9% by weight physiological saline solution at room temperature for 30 minutes and then dehydrating it at 250G for 3 minutes using a centrifuge.

(4) Absorption under Pressure (AUP)

Absorbency under pressure (AUP) was measured according to the method of the European Disposables and Nonwovens Association standard EDANA WSP 242.2.

First, a stainless steel 400 mesh wire mesh was mounted on the bottom of a plastic cylinder with an inner diameter of 60 mm. A piston is capable of uniformly spraying superabsorbent polymer W ₀ (g, 0.90 g) on a wire mesh under the conditions of room temperature and 50% humidity and applying a load of 4.83 kPa (0.7 psi) evenly on it. The outer diameter is slightly smaller than 60 mm, there is no gap with the inner wall of the cylinder, and the up and down movement is not hindered. At this time, the weight W ₃ (g) of the device was measured.

A glass filter with a diameter of 90 mm and a thickness of 5 mm was placed inside a Petro dish with a diameter of 150 mm, and a physiological saline solution composed of 0.90% by weight sodium chloride was placed at the same level as the upper 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 filter paper, and the liquid was absorbed for 1 hour under load. After 1 hour, the measuring device was lifted and the weight W ₄ (g) was measured.

Using each mass obtained in this way, AUP (g/g) was calculated according to the following equation 2 to confirm the absorbency under pressure.

[Calculation Formula 2]

AUP(g/g) = [W ₄ (g) - W ₃ (g)]/ W ₀ (g)

In equation 2 above,

W ₀ (g) is the weight of the absorbent polymer (g),

W ₃ (g) is the total weight of the absorbent polymer and the weight of the device capable of imparting a load to the absorbent polymer,

W ₄ (g) is the total weight of the moisture-absorbed absorbent polymer after supplying moisture to the absorbent polymer for 1 hour under a load (0.7 psi) and the weight of the device capable of applying a load to the absorbent polymer.

Incubation time
(hr) CFU/ml Bacterial inhibition rate (%) in Equation 1 CRC
(g/g) AUP
(g/g) Dust number in Equation 2 control group 0 2500 - 12 47,000,000,000 0 Comparative Example 1 12 13,000,000,000 About 72.3 28.5 25.7 2.2 Comparative Example 2 12 150,000,000 About 99.7 27.6 24.6 6.1 Comparative Example 3 12 180,000,000 About 99.7 27.5 24.3 10 Example 1 12 5,300,000 about 100 29.4 25.7 2 Example 2 12 14,000,000 about 100 28.6 25.9 2.1 Example 3 12 4,000,000 about 100 29.6 25.9 2.1 Example 4 12 10,200,000 about 100 29.3 25.8 2 Example 5 12 92,000 about 100 29.5 23.9 2.1 Example 6 12 1,300,000 about 100 29.1 23.8 2.2

Referring to Table 1, the superabsorbent resin of the example shows excellent bacterial growth inhibition properties, excellent deodorizing properties, or low dust generation properties compared to the comparative example, while showing no substantial decrease in water retention capacity and absorbency under pressure. Confirmed.

Claims (16)

A base resin powder containing a cross-linked polymer of a water-soluble ethylenically unsaturated monomer containing an acidic group and at least a portion of the acidic group being neutralized; and
A surface cross-linking layer is formed on the base resin powder by additional cross-linking of the cross-linking polymer using a surface cross-linking agent,
The cross-linked polymer of the base resin powder contains an antibacterial agent containing an organic acid salt having an aromatic ring within the cross-linked structure,
The organic acid salt having the aromatic ring is a superabsorbent resin contained in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the base resin powder.
The superabsorbent polymer according to claim 1, wherein the organic acid salt having an aromatic ring is a sodium (Na) salt or a zinc (Zn) salt of an organic acid having an aromatic ring.
The superabsorbent polymer according to claim 1, wherein the organic acid salt having an aromatic ring is sodium benzoate or zinc benzoate.
delete The superabsorbent polymer of claim 1, wherein the antibacterial agent further comprises ethylenediaminetetraacetic acid (EDTA) or an alkali metal salt thereof.
The superabsorbent polymer of claim 5, wherein the EDTA or its alkali metal salt is contained in an amount of 0.1 to 3 parts by weight based on 100 parts by weight of the base resin powder.
The superabsorbent polymer of claim 1, wherein the surface crosslinking agent includes a diol compound, an alkylene carbonate compound, or a polyvalent epoxy compound.
The superabsorbent polymer according to claim 1, wherein the bacterial (Esherichia Coli; ATCC25922) inhibition rate represented by the following formula 1 is 75% or more:
[Equation 1]
Bacterial inhibition rate = [1- {CFU(12h)/ CFUcontrol(12h)}]*100 (%)
In Equation 1, CFU (12h) is the amount per unit volume of artificial urine of the bacteria grown when the superabsorbent resin was added to artificial urine inoculated with bacteria of Esherichia Coli (ATCC 25922) and then cultured at 35°C for 12 hours. It represents the number of individuals (CFU/ml), and CFUcontrol (12h) is the number of individuals per unit volume of artificial urine (CFU) of the bacteria grown when the artificial urine inoculated with the bacteria was cultured under the same conditions without adding the superabsorbent resin. /ml).
The superabsorbent polymer according to claim 1, wherein the dust number is 1 to 5, calculated according to the following equation 2 from the results measured by a laser dust meter:
[Equation 2]
Dust number = Max value + 30 sec. value
In Equation 2, Max value represents the measured value when DUST is maximum when dropping the superabsorbent polymer into the laser dust meter inlet, and is measured at 30 sec. The value represents the measured value for 30 seconds after the Max value appears.
Cross-polymerizing a water-soluble ethylenically unsaturated monomer containing an acidic group and at least a portion of the acidic group neutralized in the presence of an internal cross-linking agent to form a hydrogel polymer;
Forming a base resin powder by drying, pulverizing and classifying the water-containing gel polymer; and
In the presence of a surface cross-linking agent, heat treating the base resin powder to further cross-link it,
The formation step of the hydrogel polymer is carried out in the additional presence of an antibacterial agent containing an organic acid salt having an aromatic ring,
The method for producing the superabsorbent polymer of claim 1, wherein the organic acid salt having an aromatic ring is used in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the water-soluble ethylenically unsaturated monomer.
The method of claim 10, wherein in the forming step of the water-soluble gel polymer, cross-linking polymerization is performed on an aqueous monomer solution containing the water-soluble ethylenically unsaturated monomer, a polymerization initiator, an internal cross-linking agent, and the antibacterial agent.
delete delete The method of claim 10, wherein the antibacterial agent further comprises EDTA or an alkali metal salt thereof.
The method of claim 14, wherein the EDTA or its alkali metal salt is used in an amount of 0.1 to 3 parts by weight based on 100 parts by weight of the water-soluble ethylenically unsaturated monomer or the base resin powder.
A sanitary product containing the superabsorbent polymer of claim 1.