KR20180073335A - Preparation method for super absorbent polymer, and super absorbent polymer - Google Patents

Abstract

The present invention relates to a preparation method for a super-absorbent polymer which has excellent antibacterial property and has excellent inhibitory effect on bacterial propagation, and to a super-absorbent polymer prepared thereby. The preparation method for a super absorbent polymer comprises the steps of: in the presence of an internal crosslinking agent, crosslinking and polymerizing water-soluble ethylene-based unsaturated monomers having at least partially neutralized acidic group to form a hydrogel polymer containing a crosslinked polymer; drying, pulverizing and distributing the hydrogel polymer to form base resin powder; and surface-crosslinking the base resin powder by using a surface crosslinking liquid containing a surface-crosslinking agent and cuprous oxide (I), wherein the cuprous oxide (I) may be contained in 0.001-0.1 parts by weight with respect to 100 parts by weight of the base resin powder.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a super absorbent resin,

The present invention relates to a method for producing a superabsorbent resin capable of maintaining or improving excellent absorption performance while exhibiting excellent deodorizing and antibacterial properties by inhibiting bacterial growth, and a superabsorbent resin obtained therefrom.

Super Absorbent Polymer (SAP) is a synthetic polymer material having a hydrophilic (COOH, COO ^- Na ⁺ ) functional group and capable of absorbing moisture of about 500 to 1,000 times its own weight. Super Absorbency Material (SAM), and Absorbent Gel Material (AGM). Such a superabsorbent resin has been put to practical use as a sanitary article and is currently being used as a sanitary article for children's paper diapers and the like, as well as a soil conditioner for gardening, an index material for civil engineering and construction, a sheet for seedling growing, And it is widely used as a material for fomentation and the like.

In most cases, such a superabsorbent resin is widely used in the field of sanitary materials such as diapers and sanitary napkins. For this purpose, it is necessary to exhibit a high absorption capacity for moisture and the like, In addition, there is a need to exhibit excellent permeability by keeping the form well even when the water is absorbed and expanded in volume (swollen).

In most cases, such a superabsorbent resin is widely used in the field of sanitary materials such as diapers and sanitary napkins. For this purpose, it is necessary to exhibit a high absorption capacity for moisture and the like, In addition, there is a need to exhibit excellent permeability by keeping the form well even when the water is absorbed and expanded in volume (swollen).

In addition, not only the feeling of wearing after the absorption but also the smell is also an important problem in the base absorbent resin. Therefore, it is necessary to develop an antimicrobial superabsorbent resin in order to suppress the odor caused by the metabolism activity of the microorganisms present in urine and feces.

However, in the case of the antimicrobial superabsorbent resin developed up to now, there is a limit to maintain or improve all the CRC and AUP even if the antimicrobial agent exhibits antimicrobial activity.

In addition, it is very important to introduce deodorization and antibacterial properties into the superabsorbent resin since ammonia produced by feces and bacterial growth in the sanitary material after use may cause discomfort and skin rash to consumers. It is actively underway.

However, there are many studies to kill bacteria by introducing an additive having excellent antibacterial properties into a superabsorbent resin, and there is a risk that such an antibacterial superabsorbent resin may be harmful to humans and the environment. Therefore, it is very important to develop a superabsorbent resin which suppresses the growth of bacterias, not killing bacteria, by selecting an optimal antimicrobial substance and controlling its amount.

Therefore, there is a continuing need to develop a technique for providing a superabsorbent resin having antimicrobial properties while maintaining excellent absorption performance.

The present invention provides a method for producing a highly water-absorbent resin which does not kill bacteria but exhibits optimal deodorizing and antibacterial properties by inhibiting bacterial growth and is harmless to human and environment.

The present invention also provides a method for producing a superabsorbent resin in which basic absorption properties required in a superabsorbent resin are maintained or improved and a superabsorbent resin obtained therefrom.

The present invention relates to a process for crosslinking a water-soluble ethylenically unsaturated monomer having at least partially neutralized acidic groups in the presence of an internal crosslinking agent to form a hydrogel polymer comprising a crosslinked polymer;

Drying, pulverizing and classifying the hydrogel polymer to form a base resin powder; And

Surface cross-linking the base resin powder using a surface cross-linking agent and a surface cross-linking agent containing copper oxide (I) (cuprous oxide) as an antimicrobial agent,

The copper (I) oxide includes 0.001 to 0.1 part by weight based on 100 parts by weight of the base resin powder,

A method of producing a superabsorbent resin exhibiting at least 99% bacterial growth inhibition compared to a superabsorbent resin to which copper oxide (I) is not added, in an antimicrobial test using artificial urine containing 10 ⁴ CFU / ml of bacteria and nutrients .

The present invention also relates to a base resin powder comprising a crosslinked polymer of a water-soluble ethylenically unsaturated monomer having at least partly neutralized acidic groups; And

And a surface cross-linked layer formed on the base resin powder and containing copper (I) oxide via a surface cross-linking agent,

A CRC of 30 to 50 g / g, an AUP of 16 to 25 g / g,

Exhibits at least 99% bacterial growth inhibition compared to a superabsorbent resin to which copper oxide (I) is not added, in an antimicrobial test using artificial urine containing 10 ⁴ CFU / ml of bacteria and nutrients .

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a superabsorbent resin according to a specific embodiment of the present invention and a method for producing the same will be described in detail. It is to be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

In addition, throughout this specification, "comprising" or "containing ", unless specifically stated, refers to including any and all components (or components) Can not be interpreted as excluding.

According to one embodiment of the invention, there is provided a process for crosslinking a water-soluble ethylenically unsaturated monomer having at least partially neutralized acid groups in the presence of an internal crosslinking agent to form a hydrogel polymer comprising a crosslinked polymer; Drying, pulverizing and classifying the hydrogel polymer to form a base resin powder; And surface cross-linking the base resin powder using a surface cross-linking agent comprising copper oxide (I) as a surface cross-linking agent and an antimicrobial agent, wherein the copper oxide (I) is 0.001 To 0.1 part by weight and exhibited bacterial growth inhibition of at least 99% higher than that of the superabsorbent resin not containing copper oxide (I) in an antibacterial test using artificial urine containing 10 ⁴ CFU / ml of bacteria and nutrients , A method of producing a superabsorbent resin is provided.

Thus, the superabsorbent resin of one embodiment maintains the previously known basic absorption performance or exhibits improved physical properties than those mentioned above, as well as being imparted with antibacterial properties, so that it can be highly suitably applied to various sanitary materials such as diapers.

Hereinafter, a method for producing a superabsorbent resin in one embodiment will be described in more detail.

Usually, the superabsorbent resin is prepared by polymerizing a water-soluble ethylenically unsaturated monomer having at least partially neutralized acidic groups, such as a mixture of acrylic acid and sodium salt thereof neutralized with at least part of carboxylate sodium salt or the like, Followed by surface crosslinking using a surface cross-linking solution to which a specific antimicrobial agent has been added.

However, when the superabsorbent resin absorbs contaminants such as urine and feces, there is a problem that not only the smell due to the contaminants but also the bacterial proliferation is inhibited, and a method for inhibiting the bacterial proliferation is needed. That is, as described above, the technique of completely eliminating the bacteria has been studied to develop a method of suppressing bacterial proliferation only without affecting the human body and the environment, which can be harmful to the human body and the environment.

As a result, the present invention aims to provide a superabsorbent resin which can inhibit bacterial proliferation and exhibits antimicrobial properties, but also has excellent basic properties including centrifugal separation capability (CRC) and pressure-absorbing capacity (AUP).

The method of the present invention includes a step of crosslinking the surface of the base resin powder using a surface cross-linking agent comprising a surface cross-linking agent and copper (I) (cuprous oxide) after preparing a base resin powder using a hydrogel polymer .

At this time, cuprous oxide (Cu ₂ O) added to the surface cross-linking liquid acts as an antimicrobial agent, which imparts antimicrobial properties to the surface cross-linked layer of the base resin, and the physical properties of the superabsorbent resin are basically Can be improved.

In the production method of one embodiment, the base resin powder is obtained by cross-linking polymerization of the monomer in the presence of an internal cross-linking agent, followed by surface cross-linking of the base resin powder with a predetermined surface crosslinking agent in the presence of the antimicrobial agent in a certain content range, A superabsorbent resin can be obtained.

When the copper (I) oxide is used in the surface cross-linking step, even a very small amount of copper (I) can exhibit an excellent bacterial growth inhibiting effect. Accordingly, the present invention provides an excellent effect of suppressing ammonia production due to contaminants such as feces and deodorization.

In the present invention, an antibacterial test was conducted at a low bacterial concentration of 10 ⁴ CFU / ml, not at a high concentration of 10 ⁶ CFU / ml. In the course of diluting the broth containing 10 ⁴ CFU / ml of bacteria, In addition, bacterial growth was realized. For example, the contaminant may be an artificial urine containing bacteria and nutrients at a concentration of 10 ⁴ CFU / ml, and the nutrient may include a Beef Nutrient. Thereafter, in the present invention, the artificial urine can be diluted to an appropriate concentration and cultured, and the number of colonies can be observed to measure the bacterial growth inhibition effect. According to this method, the present invention has developed an antibacterial superabsorbent resin which inhibits only the growth of bacteria.

Preferably, the superabsorbent resin according to the present invention is used in an antibacterial test using artificial urine containing bacteria and nutrients at a concentration of from 10 ⁴ to 10 ⁶ CFU / ml, at least 99% of the superabsorbent resin to which copper oxide (I) % Or 99.9% or 99.96% to 99.98% of bacterial growth inhibition.

In addition, the superabsorbent resin of the present invention can exhibit absorption functions such as Absorbency under pressure (AUP) and centrifugal separation ability (CRC) which are equal to or higher than conventional ones.

In the method of the present invention, the content of copper (I) oxide may be 0.001 to 2.5 parts by weight based on 100 parts by weight of the base resin powder, and 0.001 to 0.1 parts by weight or 0.1 to 2.5 parts by weight, if necessary. At this time, it is preferable that the content of copper oxide (I) used in the surface cross-linking solution for inhibiting only bacterial growth is 0.001 to 0.1 part by weight or 0.025 to 0.05 part by weight based on 100 parts by weight of the base resin powder. If the content of the copper (I) oxide is less than 0.001 part by weight, it may be difficult to exhibit the antibacterial property due to an excessively small amount, and if it exceeds 0.1 part by weight, the permeability may be decreased or the extract content may be increased.

In addition, the copper oxide (I) may have a crystallite size of 20 to 55 nm as measured using XRD. The copper oxide (I) may have an average particle diameter of 0.001 to 45 mu m.

In the surface cross-linking solution containing the surface cross-linking agent and copper (I) oxide (cuprous oxide), the surface cross-linking agent may be all materials well known in the art. Examples of the surface cross-linking agent include polyvalent alcohol compounds having 3 to 20 carbon atoms, epoxy compounds, polyamine compounds, haloepoxy compounds and their condensation products, oxazoline compounds, mono-, di- and poly-oxazolidinone compounds, A urea compound, a polyvalent metal salt, and an alkylene carbonate compound having 2 to 5 carbon atoms. According to a preferred embodiment, the surface cross-linking agent may be an epoxy compound, and an epoxy cross-linking agent such as EX-810 may be used.

In the surface cross-linking solution, the surface cross-linking agent may include 0.01 to 5 parts by weight, or 0.5 to 1 part by weight or 0.1 to 0.3 part by weight based on 100 parts by weight of the base resin powder.

When the copper oxide (I) is used, the base resin powder, the surface cross-linking agent, and the surface cross-linking agent containing copper oxide (I) as an antimicrobial agent are mixed and stirred for a certain period of time to progress the surface cross-linking of the base resin powder. The stirring speed may be from about 100 to 500 rpm for 5 minutes to 30 minutes.

On the other hand, in the method for producing a superabsorbent resin in one embodiment, the water-soluble ethylenically unsaturated monomer is at least one selected from the group consisting of acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, 2- acryloylethanesulfonic acid, Anionic monomers of 2- (meth) acryloylpropanesulfonic acid, or 2- (meth) acrylamide-2-methylpropanesulfonic acid and salts thereof; (Meth) acrylamide, N-substituted (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, methoxypolyethylene glycol Non-ionic hydrophilic-containing monomer of (meth) acrylate; And at least one member selected from the group consisting of an unsaturated monomer containing an amino group of (N, N) -dimethylaminoethyl (meth) acrylate or (N, N) -dimethylaminopropyl (meth) . Among them, acrylic acid or a salt thereof, for example, an alkali metal salt such as acrylic acid and / or sodium salt thereof in which at least a part of acrylic acid has been neutralized can be used. In the production of a superabsorbent resin . When acrylic acid and an alkali metal salt thereof are used as monomers, at least a part of acrylic acid may be neutralized with a basic compound such as caustic soda (NaOH).

Examples of the internal crosslinking agent for crosslinking such a monomer include bis (meth) acrylamide having 8 to 12 carbon atoms, poly (meth) acrylate of polyol having 2 to 10 carbon atoms and poly (meth) acrylate having 2 to 10 carbon atoms. And allyl ether can be used. More specifically, the internal crosslinking agent may include one selected from the group consisting of polyethylene glycol di (meth) acrylate, polypropyleneoxy di (meth) acrylate, glycerin diacrylate, glycerin triacrylate and trimethylol triacrylate Poly (meth) acrylates of the above polyol can be suitably used. Among them, use of an internal cross-linking agent such as polyethylene glycol di (meth) acrylate can provide a base resin powder having an internal cross-linking structure optimized and a high gel strength, The water absorbent resin can be obtained more appropriately.

The specific internal cross-linking agent may be used in an amount of 0.005 mole or more, or 0.005 to 0.1 mole, or 0.005 to 0.05 mole (or 0.3 parts or more, more preferably, 0.3 or more parts per 100 parts by mass of acrylic acid) based on 1 mole of the unneutralized acrylic acid contained in the monomer. Or 0.3 to 0.6 part by weight). Depending on the content range of the internal cross-linking agent, a base resin powder having a high gel strength before surface cross-linking can be appropriately obtained, and a superabsorbent resin having excellent physical properties can be obtained through the method of one embodiment.

After the cross-linking polymerization of the monomers using the internal cross-linking agent, the base resin powder can be obtained through processes such as drying, pulverization and classification. Through the steps such as pulverization and classification, the base resin powder and the The obtained superabsorbent resin is suitably manufactured and provided so as to have a particle diameter of 150 to 850 탆. More specifically, at least 95% by weight of the base resin powder and the superabsorbent resin obtained therefrom have a particle diameter of 150 to 850 탆, and the fine powder having a particle diameter of less than 150 탆 is less than 3% by weight or less than 1.5% Lt; / RTI >

As the particle size distribution of the base resin powder and the superabsorbent resin is adjusted to a preferable range, the superabsorbent resin can more appropriately exhibit the above-mentioned excellent physical properties.

Hereinafter, the method of the embodiment will be described in more detail. However, overlapping description of the above-mentioned monomers, internal cross-linking agent, antibacterial agent, particle diameter distribution and the like will be omitted and the remaining process configurations and conditions will be described step by step.

The method for producing the superabsorbent resin includes the steps of: thermally or photopolymerizing a monomer composition comprising a water-soluble ethylenically unsaturated monomer, an internal crosslinking agent and a polymerization initiator to form a hydrogel polymer comprising a crosslinked polymer; Drying the hydrogel polymer; Pulverizing and classifying the dried polymer to form a base resin powder; And surface crosslinking the base resin powder using an antimicrobial surface crosslinking solution containing a surface crosslinking agent in the presence of the copper (I) oxide.

In such a production method, the monomer composition includes a water-soluble ethylenically unsaturated monomer, an internal cross-linking agent and a polymerization initiator, and the kind of the monomer is as described above.

Also, in such compositions, the concentration of the water-soluble ethylenically unsaturated monomer may be 20 to 60% by weight or 40 to 50% by weight based on the total monomer composition including each of the raw materials and the solvent described above, And the reaction conditions. However, if the concentration of the monomer is excessively low, the yield of the superabsorbent resin may be low and economical problems may arise. Conversely, if the concentration is excessively high, a part of the monomer may precipitate or the pulverization efficiency of the polymer gel- And the physical properties of the superabsorbent resin may be deteriorated.

The polymerization initiator is not particularly limited as long as it is generally used in the production of a superabsorbent resin.

Specifically, as the polymerization initiator, a thermal polymerization initiator or a photopolymerization initiator based on UV irradiation may be used depending on the polymerization method. However, even with the photopolymerization method, a certain amount of heat is generated by irradiation with ultraviolet radiation or the like, and a certain amount of heat is generated as the polymerization reaction, which is an exothermic reaction, proceeds.

The photopolymerization initiator can be used without limitation in the constitution as long as it is a compound capable of forming a radical by light such as ultraviolet rays.

Examples of the photopolymerization initiator include benzoin ether, dialkyl acetophenone, hydroxyl alkylketone, phenyl glyoxylate, benzyl dimethyl ketal Ketal, acyl phosphine, and alpha-aminoketone may be used. On the other hand, as a specific example of the acylphosphine, a commonly used lucyrin TPO, i.e., 2,4,6-trimethyl-benzoyl-trimethyl phosphine oxide can be used . More photoinitiators are well described in Reinhold Schwalm, " UV Coatings: Basics, Recent Developments and New Applications (Elsevier 2007) " p. 115, and are not limited to the above examples.

The photopolymerization initiator may be contained in a concentration of 0.01 to 1.0% by weight based on the monomer composition. If the concentration of such a photopolymerization initiator is too low, the polymerization rate may be slowed. If the concentration of the photopolymerization initiator is too high, the molecular weight of the superabsorbent resin may be small and the physical properties may become uneven.

As the thermal polymerization initiator, at least one selected from persulfate-based initiators, azo-based initiators, initiators consisting of hydrogen peroxide and ascorbic acid can be used. Specifically, examples of the persulfate-based initiator include sodium persulfate (Na ₂ S ₂ O ₈ ), potassium persulfate (K ₂ S ₂ O ₈ ), ammonium persulfate (NH ₄ ) ₂ S ₂ O ₈ Examples of the azo initiator include 2, 2-azobis (2-amidinopropane) dihydrochloride, 2, 2-azobis (N, N-dimethylene) isobutyramidine dihydrochloride, 2- (carbamoyl azo) isobutyronitrile (2- (carbamoylazo) azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride (2-azobisisobutyronitrile) 4,4-azobis- (4-cyanovaleric acid), and the like. A variety of thermal polymerization initiators are well described in the Odian book, Principle of Polymerization (Wiley, 1981), p. 203, and are not limited to the above examples.

The thermal polymerization initiator may be contained in a concentration of 0.001 to 0.5% by weight based on the monomer composition. If the concentration of the thermal polymerization initiator is too low, additional thermal polymerization hardly occurs, and the effect of addition of the thermal polymerization initiator may be insignificant. If the concentration of the thermal polymerization initiator is excessively high, the molecular weight of the superabsorbent resin may be small and the physical properties may be uneven have.

The type of the internal crosslinking agent included in the monomer composition is as described above, and the internal crosslinking agent is contained at a concentration of 0.01 to 0.5% by weight with respect to the monomer composition so that the polymerized polymer can be crosslinked . Further, as described above, the internal cross-linking agent is used in an amount of 0.005 mole or more, or 0.005 to 0.1 mole, or 0.005 to 0.05 mole (or 100 parts by mass of acrylic acid) based on 1 mole of the unneutralized acrylic acid contained in the monomer 0.3 parts by weight or more, or 0.3 to 0.6 parts by weight). As such an internal cross-linking agent is used in such a content range, a high gel strength of the base resin powder can be suitably attained, and a superabsorbent resin can be produced which more appropriately satisfies the physical properties of the above-mentioned one embodiment.

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

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

The solvent which can be used at this time can be used without limitation of its constitution as long as it can dissolve the above-mentioned components. Examples thereof include water, ethanol, ethylene glycol, diethylene glycol, triethylene glycol, Propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, methyl ethyl ketone, acetone, methyl amyl ketone, cyclohexanone, cyclopentanone, diethylene glycol monomethyl ether, diethylene glycol At least one selected from ethyl ether, toluene, xylene, butylolactone, carbitol, methylcellosolve acetate and N, N-dimethylacetamide can be used in combination.

The solvent may be included in the remaining amount excluding the above-described components with respect to the total content of the monomer composition.

On the other hand, the method of forming a hydrogel polymer by thermal polymerization or photopolymerization of such a monomer composition is not particularly limited as long as it is a commonly used polymerization method.

Specifically, the polymerization method is largely divided into thermal polymerization and photopolymerization depending on the polymerization energy source. In general, when thermal polymerization is carried out, it may proceed in a reactor having a stirring axis such as a kneader. In the case where light polymerization is proceeded, The polymerization method described above is merely an example, and the present invention is not limited to the polymerization method described above.

For example, the hydrogel polymer obtained by supplying hot air or heating the reactor to a reactor such as a kneader having an agitating shaft as described above and thermally polymerizing it may be supplied to the reactor outlet The discharged hydrogel polymer may be in the range of a few centimeters to a few millimeters. Specifically, the size of the obtained hydrogel polymer may vary depending on the concentration of the monomer composition to be injected, the rate of injection, etc. Usually, a hydrogel polymer having a weight average particle diameter of 2 to 50 mm can be obtained.

In addition, when photopolymerization proceeds in a reactor having a movable conveyor belt as described above, the form of the hydrogel polymer usually obtained may be a hydrogel polymer on a sheet having a width of the belt. At this time, the thickness of the polymer sheet varies depending on the concentration and the injection rate of the monomer composition to be injected, but it is preferable to supply the monomer composition so that a polymer in the form of a sheet having a thickness of usually 0.5 to 5 cm can be obtained. When the monomer composition is supplied to such an extent that the thickness of the polymer in the sheet is too thin, the production efficiency is low, which is undesirable. When the thickness of the polymer on the sheet exceeds 5 cm, the polymerization reaction occurs evenly over the entire thickness due to the excessively thick thickness I can not.

In this case, the water content of the functional gel polymer obtained in this way may be in the range of 40 to 80% by weight. On the other hand, throughout the present specification, the term "moisture content" means the amount of moisture occupied by the weight of the entire functional gel polymer minus the weight of the moist gel polymer minus the weight of the dry polymer. Specifically, it is defined as a value calculated by measuring the weight loss due to moisture evaporation in the polymer in the process of raising the temperature of the polymer through infrared heating. At this time, the drying condition is a method of raising the temperature from room temperature to 180 ° C and then keeping it at 180 ° C, and the total drying time is set to 20 minutes including 5 minutes of the temperature raising step, and water content is measured.

Next, the step of drying the obtained hydrogel polymer is carried out.

At this time, if necessary, the step of coarse grinding may be further carried out before drying in order to increase the efficiency of the drying step.

In this case, the pulverizer to be used is not limited in its constitution, but may be a vertical pulverizer, a turbo cutter, a turbo grinder, a rotary cutter mill, A crusher, a disc mill, a disc mill, a shred crusher, a crusher, a chopper, and a disc cutter. However, the present invention is not limited to the above-described example.

Wherein the coarse grinding step may be pulverized so that the hydrogel polymer has a particle size of 2 to 15 mm.

The pulverization with a particle size of less than 2 mm is not technically easy due to the high moisture content of the hydrogel polymer and may also result in agglomeration among the pulverized particles. On the other hand, when the particle size is more than 15 mm, the effect of increasing the efficiency of the subsequent drying step may be insignificant.

Drying is carried out on the hydrogel polymer immediately after polymerization as described above, or without the coarse grinding step. The drying temperature of the drying step may be 150 to 250 ° C. If the drying temperature is lower than 150 ° C, the drying time becomes excessively long and the physical properties of the superabsorbent resin to be finally formed may deteriorate. When the drying temperature exceeds 250 ° C, only the polymer surface is excessively dried, And the physical properties of the finally formed superabsorbent resin may be deteriorated. Therefore, preferably, the drying can be carried out at a temperature of 150 to 200 ° C, more preferably 160 to 180 ° C.

On the other hand, the drying time may be 20 to 90 minutes in consideration of the process efficiency and the like, but is not limited thereto.

The drying method in the drying step may also be selected and used without limitation in the constitution as long as it is usually used as a drying step of the hydrous gel polymer. Specifically, the drying step can be carried out by hot air supply, infrared irradiation, microwave irradiation, ultraviolet irradiation, or the like. The water content of the polymer after such a drying step may be from about 0.1 to about 10% by weight.

Next, a step of pulverizing the dried polymer obtained through such a drying step is carried out.

The polymer powder obtained after the pulverization step may have a particle diameter of 150 to 850 탆. The pulverizer used for crushing with such a particle size is specifically a pin mill, a hammer mill, a screw mill, a roll mill, a disc mill, A jog mill, or the like may be used, but the present invention is not limited to the above examples.

Further, in order to control the physical properties of the superabsorbent resin powder which is finally produced after the pulverization step, a separate process of classifying the polymer powder obtained after pulverization according to the particle size may be performed. Preferably, the polymer having a particle diameter of 150 to 850 占 퐉 is classified, and the polymer powder having such a particle diameter can be made into a product through a surface cross-linking reaction step. Since the particle diameter distribution of the base resin powder obtained through such a process has already been described above, a further detailed description thereof will be omitted.

On the other hand, after the base resin powder is obtained through the above-described pulverization and / or classification step, the superabsorbent resin of one embodiment can be produced through the surface cross-linking step. Copper (I), which is an antimicrobial agent usable in the surface cross-linking step, has already been described above, and a description thereof will be omitted.

In this surface cross-linking step, in one example, the base resin powder may be heat-treated in the presence of the antimicrobial surface cross-linking agent containing copper oxide (I) and the surface cross-linking agent to conduct surface crosslinking.

An example of a material usable as a surface cross-linking agent in the surface cross-linking step is as described above.

In addition, the surface cross-linking liquid may further comprise water and / or methanol as a medium. This has the advantage that the surface cross-linking agent and the antibacterial agent particles can be uniformly dispersed on the base resin powder. At this time, the content of water and methanol is preferably in the range of 1: 1 to 1: 1, more preferably 1: 1 to 1: 1, By weight, based on 100 parts by weight of the composition.

Meanwhile, the surface cross-linking step may be performed by heating at 140 to 200 ° C for 5 minutes to 80 minutes. Preferably, the base resin powder to which the surface cross-linking agent is added is heated at a temperature of 140 to 200 ° C, or a maximum reaction temperature of 150 to 190 ° C for 5 to 80 minutes, or 10 to 70 minutes, or 20 to 65 Min to proceed the surface cross-linking reaction. More specifically, the surface cross-linking step raises the temperature to the maximum reaction temperature over a period of from 10 minutes to 40 minutes at an initial temperature of from 20 to 130 ° C, or from 40 to 120 ° C, Lt; RTI ID = 0.0 > and / or < / RTI >

By such surface cross-linking processing conditions, a superabsorbent resin can be produced that satisfactorily satisfies antimicrobial activity and absorption functions such as CRC and AUP.

The temperature raising means for the surface cross-linking reaction is not particularly limited. A heating medium can be supplied, or a heating source can be directly supplied and heated. The temperature of the heating medium to be supplied is not limited to the means of the heating medium, the temperature raising rate, and the temperature-raising target temperature. For example, the heating medium may be heated, And can be appropriately selected. On the other hand, as a heat source to be directly supplied, there may be mentioned a heating method using electricity or a heating method using gas, but the present invention is not limited to the above example.

On the other hand, according to another aspect of the present invention, there is provided a method for producing a water-soluble ethylenically unsaturated monomer, comprising: a base resin powder comprising a crosslinked polymer of a water-soluble ethylenically unsaturated monomer having at least partially neutralized acidic groups; And a surface cross-linked layer formed on the base resin powder and containing copper oxide (I) via a surface cross-linking agent, wherein the CRC is 30 to 50 g / g and the AUP is 16 To 25 g / g can be provided.

As already described above, the copper (I) oxide that is an antimicrobial substance may be contained in the crosslinked structure in the surface crosslinked layer or may be present in a state of being embedded in the surface of the surface crosslinked layer.

 Such a superabsorbent resin can maintain or improve physical properties such as CRC and AUP while having antibacterial properties. The physical properties of such a superabsorbent resin can be defined by the following physical property values.

First, the superabsorbent resin may have a centrifugal separation capacity (CRC) of 30 to 50 g / g.

Thus, the superabsorbent resin produced by the method of one embodiment can exhibit excellent absorbency under no pressure.

At this time, the centrifugal separation performance (CRC) of the physiological saline can be calculated by the following equation 1 after absorbing the superabsorbent resin into physiological saline over 30 minutes:

[Equation 1]

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

In the above equation 1,

W ₀ (g) is the initial weight (g) of the superabsorbent resin, and W ₁ (g) is the absorbency of the water absorbent resin in the physiological saline solution for 30 minutes, W ₂ (g) is the weight of the device after dehydration for 3 minutes. The water absorbent resin is immersed in physiological saline at room temperature for 30 minutes to absorb the water, and then dehydrated at 250 G for 3 minutes using a centrifuge, It is the weight of the device, including the resin.

In addition, the superabsorbent resin may have a pressure absorption capacity (AUP) of 16 to 25 g / g. As described above, the superabsorbent resin can exhibit excellent absorbency under pressure.

This pressure absorbing capacity (AUP) can be calculated according to the following equation 2 after the superabsorbent resin is absorbed into physiological saline under a pressure of 0.7 psi over 1 hour:

[Equation 2]

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

In the above equation 2,

W ₀ (g) is the initial weight (g) of the superabsorbent resin, W ₃ (g) is the sum of the weight of the superabsorbent resin and the weight of the device capable of imparting a load to the superabsorbent resin, W ₄ ) Is the sum of the weight of the superabsorbent resin and the weight of the device capable of imparting a load to the superabsorbent resin after absorbing the physiological saline solution into the superabsorbent resin for 1 hour under a load of 0.7 psi.

As described above, the superabsorbent resin can be exhibited excellent in absorption performance such as basic absorption power and pressure absorption power.

In particular, the above-mentioned superabsorbent resin can exhibit excellent bacterial growth inhibition as described above in an antibacterial test using artificial urine containing bacteria and nutrients at a concentration of 10 ⁴ CFU / ml.

As described above, the superabsorbent resin obtained according to the method of one embodiment can maintain or improve the basic properties such as the water absorbing ability and the pressure absorbing ability required for the superabsorbent resin, while having excellent antibacterial properties. Therefore, it can be suitably used for sanitary materials including diapers, sanitary napkins, and the like.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a process for producing a superabsorbent resin exhibiting physical properties such as centrifugal separation performance and pressure absorption ability equal to or higher than those of existing ones, suppressing bacterial growth and having excellent antibacterial properties, and a superabsorbent resin prepared therefrom.

In particular, such a superabsorbent resin suppresses the production of ammonia due to feces and bacterial growth, and exhibits excellent deodorizing and antibacterial properties, thereby enhancing the fit of the consumer and suppressing skin rash. Therefore, the superabsorbent resin can be suitably used for sanitary materials such as diapers.

Fig. 1 shows comparative photographs of Comparative Example 1 and photographs of antibacteriality test results of the superabsorbent resins of Examples 1 and 2 according to one embodiment of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the scope of the present invention is not limited to the following examples.

In the following Examples and Comparative Examples, the physical properties of each superabsorbent resin were measured and evaluated in the following manner.

(One) Particle size evaluation

The particle sizes of the base resin powder and superabsorbent resin used in Examples and Comparative Examples were measured according to the EDANA WSP 220.3 method of the European Disposables and Nonwovens Association (EDANA).

(2) Centrifugation Function  ( CRC , Centrifuge Retention Capacity)

According to EDANA WSP 241.3 of the European Disposables and Nonwovens Association (EDANA) standard, the centrifugal separation performance (CRC) of the superabsorbent resins of Examples and Comparative Examples was measured by the zero load absorption capacity.

That is, the resin W ₀ (g, about 0.2 g) in Examples and Comparative Examples was uniformly put in an envelope made of a nonwoven fabric and sealed, and then immersed in physiological saline at 0.9% by weight aqueous sodium chloride solution at room temperature. After 30 minutes using a centrifuge after the envelope, leave for 3 minutes to dry 250G was measured mass W ₂ (g) of the bag. After the same operation was performed without using a resin, the mass W ₁ (g) at that time was measured.

Using each of the masses thus obtained, the CRC (g / g) was calculated according to the following equation 1 to confirm the maintenance performance.

[Equation 1]

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

In the above equation 1,

W ₀ (g) is the initial weight (g) of the superabsorbent resin,

W ₁ (g) is the weight of the device measured after immersing in physiological saline for 30 minutes to absorb and then dehydrating for 3 minutes at 250 G using a centrifuge without using a superabsorbent resin,

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

(3) Pressurization Absorption capacity (Absorbency under Pressure, AUP )

Absorbency under pressure (AUP) was measured according to the method of European Disposables and Nonwovens Association standard EDANA WSP 242.3 for superabsorbent resins of Examples and Comparative Examples.

First, a 400 mesh wire mesh made of stainless steel was attached to the bottom of a plastic cylinder having an inner diameter of 60 mm. The resin W ₀ (g, 0.90 g) obtained in Examples 1 to 6 and Comparative Examples 1 to 3 was uniformly sprayed on a iron mesh at a temperature of 23 ± 2 ° C. and a relative humidity of 45% psi) is slightly smaller than the outer diameter of 60 mm, so that there is no gap between the inner wall of the cylinder and the up and down movement is prevented from being disturbed. At this time, the weight W ₃ (g) of the device was measured.

A glass filter having a diameter of 125 mm and a thickness of 5 mm was placed inside a Petro dish having a diameter of 150 mm, and physiological saline composed of 0.90% by weight sodium chloride was made to have the same level as the upper surface of the glass filter. And a filter paper having a diameter of 120 mm was placed thereon. The measuring device was placed on the filter paper and the liquid was absorbed under load for 1 hour. After one hour, the measuring device was lifted and its weight W ₄ (g) was measured.

Using each mass thus obtained, AUP (g / g) was calculated according to the following equation 2 to confirm the pressure absorption ability.

[Equation 2]

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

In the above equation 2,

W ₀ (g) is the initial weight (g) of the superabsorbent resin,

W ₃ (g) is the sum of the weight of the superabsorbent resin and the weight of the device capable of applying a load to the superabsorbent resin,

W ₄ (g) is the sum of the weight of the superabsorbent resin and the weight of the device capable of imparting a load to the superabsorbent resin after absorbing physiological saline into the superabsorbent resin for 1 hour under a load of 0.7 psi.

(4) Permeability (also called permeability)

A line was drawn on the liquid surface of 20 ml and 40 ml in the state in which the piston was placed in a chromatography tube (? 20 mm). About 10 ml of brine was filled and 0.2 g of 30 # ~ 50 # was added. Then, brine was added to make the total amount of brine to be 50 ml. And allowed to stand for 30 minutes so that the superabsorbent resin was sufficiently swollen. An additional piston (0.3 psi) was placed in the chromatographic tube and allowed to stand for one minute. After opening the stopper at the bottom of the chromatography tube, time (T1: sec) was recorded from 40 ml to 20 ml marking line.

After repeating from 4.2 to 4.5 with a blank obtained by subtracting the superabsorbent resin, the required time (B1) was recorded.

[Equation 3]

Permeability (sec.) = T1 - B

(5) Vortex  Vortex test

50.0 ± 1.0 mL of 0.9% NaCl solution was added to a 100 mL beaker. A cylindrical stir bar (30 x 6 mm) was added and the solution was stirred on a stir plate at 600 rpm. 2.000 ± 0.010 g of water-absorbing polymer particles were added to the beaker at one time as soon as possible, and the stopwatch was started while the addition was initiated. The stopwatch is stopped when the surface of the mixture becomes "still ", meaning that the surface does not have turbulence, while the mixture still rotates, Lt; / RTI > The time displayed on the stopwatch was recorded as the vortex time.

(6) CFU  Analysis (antibacterial test)

2 mL of artificial urine containing 10 ⁴ CFU / ml of bacteria and nutrients was mixed with 0.1 g of superabsorbent resin to prepare a gel. Thereafter, the weight was increased and a pressure of 0.7 psi was applied, and the mixture was stirred at 25 DEG C at 110 rpm through a stirrer. The agitation time was limited to a maximum of 12 hours. After stirring, the mixture was washed with 18 mL of 0.9% saline and diluted to an appropriate concentration. Thereafter, the cells were coated on a previously prepared agar medium, cultured for 18 hours, and the number of colonies was recorded and the concentration was calculated.

< Example  1>

In the reactor, 100 g of acrylic acid, 36.2 g of sodium hydroxide, 0.21 g of polyethylene glycol diacrylate (Mw = 598) as a crosslinking agent, 0.008 g of diphenyl (2,4,6-trimethylbenzoyl) -phosphine oxide as a UV initiator, 0.03 g (0.03 parts by weight) of an additive and 121.5 g of water were mixed to prepare a water-soluble unsaturated monomer composition having an acrylic acid monomer concentration of 36.7% by weight.

At this time, garamite 2578, a mixed product having a plate shape and a rod structure, was used as the modifying clay additive. Garamite 2578 is a product of clay having a plate and rod structure modified by an amine-based organic compound of an alkyl quaternary alkyl ammonium ion and having an amine group introduced on its surface. And the clay is modified by using the above-mentioned amine-based organic compound.

Thereafter, the monomer composition was introduced through a feeder of a polymerization reactor consisting of a conveyor belt continuously moving, and UV polymerization was conducted for 2 minutes by irradiating ultraviolet rays (irradiation amount: 2 mW / cm 2) through a UV irradiator to obtain a hydrogel polymer .

The hydrogel polymer was transferred to a cutter and cut to 0.2 cm.

Then, the hydrogel polymer was dried in a hot-air drier at 185 ° C for 40 minutes, and the dried hydrogel polymer was pulverized with a pin mill. Thereafter, the resultant was classified into a standard network of ASTM standard to obtain a polymer (base resin powder) having a particle size (average particle size) of 150 μm to 850 μm.

Then, 100 parts by weight of the base resin powder was mixed with cuprous oxide (Cupron A) having the same contents as in the following Table 1, 0.2 parts by weight of EX-810 (epoxy cross-linking agent), 5 parts by weight of water, And 3 parts by weight of methanol were mixed at 500 rpm for 30 seconds to form an antimicrobial surface treatment liquid. The surface treatment liquid was sprayed onto the base resin powder and stirred at room temperature to mix the surface treatment liquid evenly distributed to the base resin powder. Then, the base resin powder was put into a surface cross-linking reactor and the surface cross-linking reaction proceeded.

At this time, the surface-treated superabsorbent resin was prepared by heating reaction at 180 ° C for 40 minutes. Specifically, in the surface cross-linking reactor, the base resin powder into which the antimicrobial surface cross-linking liquid was sprayed was confirmed to be gradually heated at an initial temperature of about 20 캜, and after a lapse of 20 minutes, the maximum reaction temperature of 180 캜 was reached . After reaching the maximum reaction temperature, the final prepared superabsorbent resin sample was taken after additional reaction for 40 minutes. After the surface cross-linking step, a surface crosslinked superabsorbent resin having a particle diameter of about 150 to 850 탆 was obtained by using a sieve.

< Example  2>

A superabsorbent resin was prepared in the same manner as in Example 1 except that the content of copper (I) oxide in the surface cross-linking solution was changed.

That is, 0.05 part of cupron A oxide, 0.2 part of EX-810 (epoxy crosslinking agent) as a surface cross-linking agent, 5 parts of water and 3 parts of methanol were added to 100 parts by weight of the base resin powder at 500 rpm For 30 seconds, followed by crosslinking at 180 degrees for 40 minutes.

< Comparative Example  1>

A superabsorbent resin was prepared in the same manner as in Example 1, except that copper (I) oxide was not added in the surface cross-linking solution.

That is, 0.2 parts by weight of EX-810 (epoxy crosslinking agent) as a surface cross-linking agent, 5 parts by weight of water and 3 parts by weight of methanol were mixed at 500 rpm for 30 seconds with respect to 100 parts by weight of the base resin powder, .

< Experimental Example  1>

The superabsorbent resins of Examples 1 and 2 and Comparative Example 1 were subjected to measurement and evaluation of physical properties such as CRC and AUP. The measured physical properties are shown in Table 1 below.

sample CRC
(g / g) AUP
(g / g) permeability Vertex
(s) Example 1 SAP + Cuprous oxide 0.025 phr 36.4 22.8 755 s 44 Example 2 SAP + Cuprous oxide 0.05 phr 36.7 22.7 636 h 43 Comparative Example 1 SAP 36.8 22.6 669 h 45

Referring to Table 1, it can be seen that the superabsorbent resins of Examples 1 and 2 exhibit absorption characteristics (CRC, AUP, etc.) equal to or higher than those of Comparative Example 1.

< Experimental Example  2>

According to the above-described antibacterial test method, the bacterial growth effect was examined for Example 1-2 and Comparative Example 1. [ The results are shown in FIG. 1 and Table 2. Fig. 1 shows comparative photographs of Comparative Example 1 and photographs of antibacteriality test results of the superabsorbent resins of Examples 1 and 2 according to one embodiment of the present invention.

Bacterial concentration (CFU / mL) according to incubation time (h) 0h 2h 4h 6h 8h 24h 24h
Antimicrobial activity (%) Comparative Example 1 16,000 13,200 14,900 12,300 12,300 24,300 Standard Example 1 15,200 9,100 700 500 2,000 1,000 99.96 Example 2 15,200 6,800 600 200 200 600 99.98

As shown in the results of Table 2 and FIG. 2, as a result of the antibacterial test of Comparative Example 1 and Example 1-2, the bacterial proliferation of Comparative Example 1 was greater than that of Example 1-2.

That is, in Comparative Example 1, 1.6 × 10 ³ CFU / ml of bacteria increased to 2.43 × 10 ⁴ CFU / ml after 24 hours. However, in Examples 1 and 2 of the present invention, bacterial proliferation was suppressed to 1.0 × 10 ³ CFU / ml and 6.0 × 10 ² CFU / ml, respectively, as compared with Comparative Example 1. This means that the introduction of a very small amount of Cupron A of 250 ppm or 500 ppm inhibits bacterial growth by 99.96% and 96.98%, respectively.

In addition, the superabsorbent resin prepared by adding a specific antimicrobial agent such as copper (I) oxide to the base resin powder during the surface cross-linking process has CRC, AUP, and moisture permeability similar to Comparative Example 1 (Cupron A 0% permeability, and vortex values.

Claims (10)

Crosslinking a water-soluble ethylenically unsaturated monomer having at least partially neutralized acidic groups in the presence of an internal crosslinking agent to form a hydrogel polymer comprising a crosslinked polymer;
Drying, pulverizing and classifying the hydrogel polymer to form a base resin powder; And
Surface cross-linking the base resin powder using a surface cross-linking agent and a surface cross-linking agent containing copper (I) oxide as an antimicrobial agent,
The copper (I) oxide includes 0.001 to 0.1 part by weight based on 100 parts by weight of the base resin powder,
A method of producing a superabsorbent resin exhibiting at least 99% bacterial growth inhibition compared to a superabsorbent resin to which copper oxide (I) is not added, in an antimicrobial test using artificial urine containing 10 ⁴ CFU / ml of bacteria and nutrients .
The method of producing a superabsorbent resin according to claim 1, wherein the copper oxide (I) has a crystallite size of 20 to 55 nm and an average particle size of 0.001 to 45 μm.
The surface cross-linking agent according to claim 1, wherein the surface cross-linking agent is selected from the group consisting of a polyhydric alcohol compound having 3 to 20 carbon atoms, an epoxy compound, a polyamine compound, a haloepoxy compound and condensation product thereof, an oxazoline compound, a mono-, di-, and poly-oxazolidinone compound , A cyclic urea compound, a polyvalent metal salt, and an alkylene carbonate compound having 2 to 5 carbon atoms.
The method for producing a superabsorbent resin according to claim 1, wherein the surface cross-linking step is carried out by heating at a temperature of 140 to 200 ° C for 5 minutes to 80 minutes.
The method according to claim 1,
Wherein the surface cross-linking liquid further comprises water, methanol or a mixture thereof.
The water-soluble ethylenically unsaturated monomer according to claim 1, wherein the water-soluble ethylenically unsaturated monomer is at least one selected from the group consisting of acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, 2- acryloylethanesulfonic acid, 2- (Meth) acryloylpropanesulfonic acid, or an anionic monomer of 2- (meth) acrylamide-2-methylpropanesulfonic acid and its salt; (Meth) acrylamide, N-substituted (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, methoxypolyethylene glycol Non-ionic hydrophilic-containing monomer of (meth) acrylate; And at least one member selected from the group consisting of an unsaturated monomer containing an amino group of (N, N) -dimethylaminoethyl (meth) acrylate or (N, N) -dimethylaminopropyl (meth) By weight.
The method according to claim 1, wherein the internal crosslinking agent is at least one selected from the group consisting of bis (meth) acrylamides having 8 to 12 carbon atoms, poly (meth) acrylates of polyols having 2 to 10 carbon atoms and poly (meth) allyl ethers of polyols having 2 to 10 carbon atoms By weight based on the total weight of the composition.
The method of producing a superabsorbent resin according to claim 1, wherein the base resin powder is pulverized and classified to have a particle diameter of 150 to 850 탆.
The process according to claim 1, wherein the CRC is 30 to 50 g / g and the AUP is 16 to 25 g / g.
A base resin powder comprising a crosslinked polymer of a water-soluble ethylenically unsaturated monomer having at least partly neutralized acidic groups; And
And a surface cross-linked layer formed on the base resin powder and containing copper (I) oxide via a surface cross-linking agent,
A CRC of 30 to 50 g / g, an AUP of 16 to 25 g / g,
Absorbent resin exhibiting at least 99% bacterial growth inhibition compared to a superabsorbent resin to which copper oxide (I) is not added, in an antimicrobial test using artificial urine containing 10 ⁴ CFU / ml of bacteria and nutrients.

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