KR102213451B1 - Super absorbent polymer and method for preparing the same - Google Patents

Abstract

A particulate crosslinked polymer comprising a plurality of particles, comprising: preparing a particulate crosslinked polymer having an internal network structure and crosslinked on the surface; And mixing the particulate crosslinked polymer and a binder to combine one particle and another particle.

Description

Super absorbent polymer and its manufacturing method TECHNICAL FIELD [SUPER ABSORBENT POLYMER AND METHOD FOR PREPARING THE SAME}

The present invention relates to a super absorbent polymer and a method for producing a super absorbent polymer.

Super Absorbent Polymer (SAP) is a synthetic polymer material that has a function of absorbing moisture 500 to 1,000 times its own weight, and each developer has a SAM (Super Absorbency Material), AGM (Absorbent Gel Material). ) And so on. Since the above superabsorbent resin has begun to be put into practical use as a sanitary tool, nowadays, in addition to hygiene products such as paper diapers for children, soil repair agents for horticulture, water resistant materials for civil engineering and construction, sheets for seedlings, freshness maintenance agents in the food distribution field, and poultice. It is widely used as a material for supplies.

As a method of preparing the super absorbent polymer as described above, a method by reverse phase suspension polymerization or a method by aqueous solution polymerization is known. Regarding reverse-phase suspension polymerization, for example, Japanese Patent Publication No. 56-161408, Japanese Patent Publication No. 57-158209, and Japanese Patent Publication No. 57-198714 are disclosed. As a method of aqueous solution polymerization, a thermal polymerization method in which heat is applied to the aqueous solution to polymerize, and a photopolymerization method in which polymerization is performed by irradiation with ultraviolet rays or the like are known.

On the other hand, as the uses of super absorbent polymers diversify, absorption ratio, centrifuge retention capacity (CRC), absorption under pressure (AUP), free swelling rate (FSR), and liquid permeability (Gel) Bed Permeability, GBP), antibacterial properties, filling properties, etc. are required.

The fine powder of the water absorbent resin, which may occur during the manufacturing process of the super absorbent polymer, has poor physical properties such as water holding capacity, absorbency under pressure, or liquid permeability, and if included in the product, it may cause a decrease in the properties of the entire product. . As a method to solve this problem, a method of discarding the fine powder generated through the classification process can be illustrated. However, this method is not cost-effective due to the loss of the manufactured water absorbent resin.

Accordingly, the problem to be solved by the present invention is to provide a method of manufacturing a super absorbent polymer capable of minimizing loss due to fine powder by recycling fine powder generated in the manufacturing process of the super absorbent polymer.

Another problem to be solved by the present invention is to provide a superabsorbent polymer having sufficient water holding capacity, absorption capacity under pressure, and liquid permeability, and improved absorption rate despite recycling of fine powder.

The problems of the present invention are not limited to the technical problems mentioned above, and other technical problems that are not mentioned will be clearly understood by those skilled in the art from the following description.

A method for preparing a super absorbent polymer according to an embodiment of the present invention for solving the above problems is a step of preparing a particulate crosslinked polymer having an internal network structure and a surface crosslinked crosslinked polymer as a particulate crosslinked polymer including a plurality of particles, and And mixing the particulate crosslinked polymer and a binder to combine one particle and another particle.

The step of preparing the particulate crosslinked polymer having an internal network structure and crosslinked on the surface includes preparing a hydrogel crosslinked polymer by polymerizing a hydrophilic monomer composition, pulverizing the hydrogel crosslinked polymer, and the pulverized particulate crosslinked polymer It may include the step of surface crosslinking.

In addition, the step of surface crosslinking the particulate crosslinked polymer includes mixing the pulverized particulate crosslinked polymer with a silica-based material, mixing the crosslinked polymer mixed with the silica-based material with a surface crosslinking agent, and the surface crosslinking agent It may include a step of heat-treating the mixed crosslinked polymer.

Between the step of preparing the particulate crosslinked polymer having the internal network structure and crosslinking the surface and combining the particulate crosslinked polymer and the binder to bind the particles and other particles, the surface crosslinked particulate crosslinked polymer is used as a first particulate crosslinked polymer. And classifying into a second particulate crosslinked polymer having a particle size smaller than that of the first particulate crosslinked polymer. The step of combining the particulate crosslinked polymer and a binder to combine the particles and other particles comprises: It may be a step of combining the crosslinked polymer, the second particulate crosslinked polymer, and the binder to combine the first particulate crosslinked polymer and the second particulate crosslinked polymer.

The step of mixing the particulate crosslinked polymer and the binder may be a step of mixing 2 to 5 parts by weight of the binder based on 100 parts by weight of the particulate crosslinked polymer.

In addition, the particulate crosslinked polymer includes a first particulate crosslinked polymer having a particle size of 150 μm or more and a second particulate crosslinked polymer having a particle size of less than 150 μm, and in the step of mixing the particulate crosslinked polymer and a binder, the second particulate crosslinked polymer May be included in the range of 1% by weight or more and 10% by weight or less based on the total weight of the particulate crosslinked polymer.

The binder may be distilled water.

The binder may be a binder solution containing a cationic binder material.

The superabsorbent polymer according to an embodiment of the present invention for solving the above problems is a particulate superabsorbent resin including a plurality of particles, and one of the particles has an internally crosslinked network structure, but the crosslinking density is partially A different first sub-particle, and a second sub-particle bonded to the first sub-particle and having an internally cross-linked network structure, wherein the cross-linking density of a portion of the first sub-particle bonded to the second sub-particle is It is greater than the crosslinking density inside the first sub-particle.

The one particle may further include a binder layer interposed between the first sub-particle and the second sub-particle to couple the first sub-particle and the second sub-particle.

In addition, the binder layer may include a cationic material.

A moisture content of a portion of the first sub-particle that is bonded to the second sub-particle may be greater than that of the first sub-particle.

The superabsorbent polymer according to an embodiment of the present invention for solving the above problems is a particulate superabsorbent resin including a plurality of particles, wherein one of the particles is a first having a crosslinking density gradually increasing in one direction. A portion and a second portion in which the crosslinking density gradually decreases along the one direction are sequentially disposed adjacent to each other.

The superabsorbent polymer according to an embodiment of the present invention for solving the above problems is a particulate superabsorbent resin including a plurality of particles, wherein one of the particles is a first having a crosslinking density gradually increasing in one direction. A portion, a second portion having a crosslinking density smaller than the maximum crosslinking density of the first portion, but maintaining a crosslinking density along the one direction, and a third portion gradually increasing the crosslinking density along the one direction are sequentially Includes contiguous areas.

Details of other embodiments are included in the detailed description and drawings.

According to the embodiments of the present invention, there are at least the following effects.

According to the method for producing a super absorbent polymer according to an embodiment of the present invention, the loss of the prepared water absorbent resin can be minimized by mixing a binder with a particulate crosslinked polymer to combine the crosslinked polymer particles and fine powder. It is possible to prepare a super absorbent polymer having improved speed.

In addition, by surface crosslinking the particulate crosslinked polymer before mixing the binder, a super absorbent polymer having sufficient water holding capacity, water absorption under pressure, and/or liquid permeability can be produced even though fine powder is included.

In addition, a super absorbent polymer with improved liquid permeability may be prepared by using a binder solution containing a cationic material as the binder.

Effects according to the embodiments of the present invention are not limited by the contents illustrated above, and more various effects are included in the present specification.

1 is a flow chart showing a method of manufacturing a super absorbent polymer according to an embodiment of the present invention.
2 is a schematic diagram showing a particle shape of a super absorbent polymer according to an embodiment of the present invention.
3 is a schematic diagram showing a particle shape of a super absorbent polymer according to another embodiment of the present invention.
4 to 6 are schematic diagrams showing the particle shape of a super absorbent polymer according to still other embodiments of the present invention.

Advantages and features of the present invention, and a method of achieving them will become apparent with reference to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms different from each other, and only the embodiments make the disclosure of the present invention complete, and those skilled in the art to which the present invention pertains. It is provided to fully inform the person of the scope of the invention, and the invention is only defined by the scope of the claims.

In the present specification, "C _AB " indicates that the number of carbon atoms is A or more and B or less. For example, a C _1-5 alkyl group means an alkyl group having 1 to 5 carbon atoms. "And/or" includes each and every combination of one or more of the recited items. Numerical ranges indicated using "to" represent numerical ranges including the values listed before and after them as lower and upper limits, respectively, unless otherwise indicated. The same reference numerals refer to the same components throughout the specification.

Although the first, second, and the like are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are only used to distinguish one component from another component.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a flow chart showing a method of manufacturing a super absorbent polymer according to an embodiment of the present invention.

Referring to FIG. 1, a method for preparing a super absorbent polymer according to an embodiment of the present invention is a particulate crosslinked polymer including a plurality of particles, and prepares a crosslinked particulate crosslinked polymer having an internal network structure. Step (S100), classifying the surface crosslinked particulate crosslinked polymer into a first particulate crosslinked polymer and a second particulate crosslinked polymer having a particle size smaller than that of the first particulate crosslinked polymer (S200), and a first particulate crosslinked polymer, a second It may include a step (S300) of mixing the particulate crosslinked polymer and a binder.

Specifically, the step of preparing a crosslinked particulate polymer having an internal network structure (S100) is a step of preparing a crosslinked hydrogel polymer by polymerizing a hydrophilic monomer composition (S110), cutting, grinding and drying the crosslinked hydrogel polymer The step of preparing a particulate crosslinked polymer (S120), and a step of surface crosslinking the particulate crosslinked polymer (S130) may be included.

First, a hydrophilic monomer composition is polymerized to prepare a hydrogel crosslinked polymer (S110). The hydrophilic monomer composition is a raw material for forming a crosslinked polymer, such as a hydrogel crosslinked polymer, and may include a hydrophilic monomer, an internal crosslinking agent, and a polymerization initiator.

The hydrophilic monomer may be a monomer having a hydrophilic group such as a hydroxyl group (-OH), a carboxyl group (-COOH), an amide group (-NH ₂ ), and the like. The hydrophilic monomer is not limited as long as it is generally used in the preparation of a super absorbent polymer, but may be, for example, a water-soluble ethylenically unsaturated monomer. As the water-soluble ethylenically unsaturated monomer, an anionic monomer and a salt thereof, a nonionic hydrophilic-containing monomer, or an amino group-containing unsaturated monomer and a quaternary product thereof can be exemplified.

Specific examples of the anionic monomer include acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, 2-acryloylethane sulfonic acid, 2-methacryloylethanesulfonic acid, and 2-(meth)acrylo. And ylpropanesulfonic acid and 2-(meth)acrylamide-2-methylpropanesulfonic acid.

Specific examples of the nonionic hydrophilic-containing monomer include (meth)acrylamide, N-substituted (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and And oxypolyethylene glycol (meth)acrylate and polyethylene glycol (meth)acrylate.

Specific examples of the amino group-containing unsaturated monomer include (N,N)-dimethylaminoethyl (meth)acrylate and (N,N)-dimethylaminopropyl (meth)acrylamide.

The content of the water-soluble ethylenically unsaturated monomer in the hydrophilic monomer composition may be appropriately selected in consideration of the type of the reactor and/or polymerization conditions, but may be, for example, in the range of about 30% by weight to 60% by weight.

The internal crosslinking agent is a crosslinking agent that crosslinks the interior of a crosslinked polymer, such as a hydrogel crosslinked polymer, to form a network crosslinked structure such as a three-dimensional network structure. The internal crosslinking agent has a functional group capable of reacting with a functional group of a hydrophilic monomer and at least one ethylenically unsaturated group, or two functional groups capable of reacting with a hydrophilic functional group formed by hydrolyzing a functional group of a hydrophilic monomer and/or a hydrophilic monomer. It may be an internal crosslinking agent having the above. Internal cross-linking agent include, but are not limited so long as that generally used in the production of water-absorbent resin, for example, C _8-12 bisacrylamide, C _8-12 bismethacrylate acrylamide, poly (meth) acrylate of a C _2-12 polyol , C _2-10 polyol of poly(meth)allyl ether, or a mixture thereof.

Specific examples of the internal crosslinking agent include (poly) ethylene glycol (meth) acrylate, (poly) propylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, ethoxyl (3)-trimethylolpropane Tri(meth)acrylate, ethoxyl(6)-trimethylolpropane tri(meth)acrylate, ethoxyl(9)-trimethylolpropane tri(meth)acrylate, ethoxyl(15)-trimethylolpropanetri( Meth)acrylate glycerin tri(meth)acrylate, glycerin acrylate methacrylate, 2,2-bis[(acryloxy)methyl]butyl acrylate (3EO), N,N'-methylenebis(meth)acrylate , Ethyleneoxy(meth)acrylate, polyethyleneoxy(meth)acrylate, propyleneoxy(meth)acrylate, glycerin, glycerin diacrylate, glycerin triacrylate, trimethylol triacrylate, triallylamine, triaryl Cyanurate, triallyl isocyanate, pentaethyleneimine, ethylene glycol, polyethylene glycol diethylene glycol, polyethylene glycol diacrylate, polymethylolpropane triacrylate, propylene glycol, and the like, but are not limited thereto.

The content of the internal crosslinking agent in the hydrophilic monomer composition may be appropriately selected in consideration of the type of polymerization reaction and/or polymerization conditions, but may be, for example, in the range of about 0.001% by weight or more and 2.0% by weight or less.

The polymerization initiator is a material for initiating a crosslinking polymerization reaction by an internal crosslinking agent. The polymerization initiator may include at least one of a photo polymerization initiator, a thermal polymerization initiator, and an oxidation-reduction polymerization initiator depending on the type of polymerization reaction. For example, the monomer composition may include a photo polymerization initiator and a thermal polymerization initiator together.

Specific examples of the photopolymerization initiator include diethoxy acetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 4-(2-hydroxy ethoxy)phenyl-(2-hydroxy) Acetophenone derivatives such as -2-propyl ketone and 1-hydroxycyclohexylphenyl ketone, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin alkyl ether compounds such as benzoin isobutyl ether, Benzophenone derivatives such as methyl o-benzoyl benzoate, 4-phenyl benzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, (4-benzoyl benzyl) trimethylammonium chloride, thioxanthone compounds, bis (2,4,6-trimethylbenzoyl)-phenyl phosphine oxide, diphenyl (2,4,6-trimethylbenzoyl)-phosphine oxide, diphenyl (2,4,5-trimethylbenzoyl)-phosphine oxide Acyl phosphine oxide derivatives such as, or 2-hydroxy methyl propionnitrile, 2,2'-(azobis(2-methyl-N-(1,1'-bis(hydroxymethyl)-2-hydroxyethyl) ) Azo-based compounds such as propion amide), and the like.

Specific examples of the thermal polymerization initiator include an azo initiator, a peroxide initiator, a redox initiator, an organic halide initiator, sodium persulfate (Na2S2O8), and potassium persulfate (K2S2O8). ), etc.

The content of the polymerization initiator in the monomer composition may be appropriately selected so as to exhibit a polymerization initiation effect. For example, the photopolymerization initiator may be included in the range of about 0.005 to 0.1 parts by weight based on 100 parts by weight of the hydrophilic monomer, and the thermal polymerization initiator may be included in the range of about 0.01 to 0.5 parts by weight based on 100 parts by weight of the hydrophilic monomer.

In an exemplary embodiment, the step of preparing the hydrogel crosslinked polymer (S110) may be a step of photopolymerizing the hydrophilic monomer composition in a continuous reactor to form a sheet-shaped hydrogel crosslinked polymer.

The continuous reactor is a belt-type continuous reactor, and the light may be a light source such as an Xe lamp, a mercury lamp, or a metal halide lamp, but is not limited thereto.

Specifically, the light may be ultraviolet rays having a wavelength in the range of about 200 nm to 400 nm. The exposure amount and irradiation time of light can be appropriately selected in consideration of the reaction conditions. For example, the light may be irradiated for a time in the range of about 10 seconds to 5 minutes, or about 20 seconds to 3 minutes at an exposure amount in the range of about 0.5 mW/cm ² to 500 mW/cm ² . An effective photopolymerization reaction may occur within the wavelength, exposure amount, and irradiation time range, and it is possible to prevent the crosslinking point of the polymer from being cut due to excessive light irradiation.

In another embodiment, the step of preparing the hydrogel crosslinked polymer (S110) may be a step of thermally polymerizing the hydrophilic monomer composition or oxidation-reduction polymerization to form the hydrogel crosslinked polymer.

Subsequently, the hydrogel crosslinked polymer is cut, pulverized and dried to prepare a particulate crosslinked polymer (S120). In an exemplary embodiment, the step of cutting, grinding, and drying the hydrogel crosslinked polymer (S120) is a step of preparing a particulate crosslinked polymer by cutting and pulverizing the sheet-shaped hydrogel crosslinked polymer (S121), drying the particulate crosslinked polymer. Step (S122) and the step (S123) of secondary pulverization of the dried particulate crosslinked polymer may be included, but in other embodiments, one or more of the cutting, pulverizing and drying processes are omitted, or a pulverizing and drying process is further included. May be.

In the step of cutting and pulverizing the hydrogel crosslinked polymer (S121), pre-cutting the sheet-shaped hydrogel crosslinked polymer obtained after the polymerization reaction is completed, and chopping the pre-cut crosslinked polymer into the particulate crosslinked polymer. It can be a step. The pre-cutting may use a cutter-type cutter or a kneader-type cutter, and the pulverization may be performed using a chopper-type cutter, but is not limited thereto.

In the step of drying the particulate crosslinked polymer (S122), the moisture content inside the hydrogel crosslinked polymer is dried to lower the moisture content to form a water absorbent crosslinked polymer having an internal network structure, and at the same time, crosslinking to consume unreacted residual monomer. It may be a step of heating the polymer. The heating may be performed using a hot air dryer, fluid bed dryer, air flow dryer, infrared dryer, or dielectric heating dryer, but is not limited thereto. In addition, the drying is carried out at a temperature in the range of about 100° C. to 200° C., or about 150° C. to 180° C. for a time in the range of about 20 to 80 minutes, or about 30 to 70 minutes, or about 40 to 60 minutes Can be. In the above temperature and drying time range, deterioration of the crosslinked polymer is prevented and efficient drying is possible.

The step of secondary pulverizing the particulate crosslinked polymer (S123) may be a step for further pulverizing the dried particulate crosslinked polymer to make the average particle size of the particulate crosslinked polymer smaller and to make the particle size distribution uniform. The pulverization may be performed using a vibration type pulverizer, an impact type pulverizer, a friction type pulverizer, or a pin mill pulverizer, but is not limited thereto.

Subsequently, the particulate crosslinked polymer is surface crosslinked (S130). In the present specification, surface crosslinking or surface crosslinking treatment refers to a surface modification treatment that increases the crosslinking density in the vicinity of the particle surface. That is, it is a treatment for enhancing the crosslinkability of the surface of the particle without substantially affecting the crosslinked structure inside the particle. In particular, by surface crosslinking the crosslinked polymer before the step of mixing the particulate crosslinked polymer and the binder (S300) to be described later, a water absorbent resin having sufficient water holding capacity, absorption capacity under pressure, and/or liquid permeability can be prepared despite recycling of fine powder. .

In an exemplary embodiment, the step of surface crosslinking the particulate crosslinked polymer (S130) includes mixing the particulate crosslinked polymer with a silica-based material (S131), mixing the silica-treated particulate crosslinked polymer with a surface crosslinking agent (S132), and It may include a step (S133) of heat-treating the particulate crosslinked polymer mixed with the surface crosslinking agent.

In the step of mixing the particulate crosslinked polymer with a silica-based material (S131), in the step (S132) of performing silica treatment on the surface of the particulate crosslinked polymer and mixing it with a surface crosslinking agent (S132), agglomeration between the crosslinked polymer particles is reduced, and It may be a step of improving liquidity. The mixing may be performed using a mixer, such as a powder mixer. The silica-based material may be mixed in an amount of about 0.1 to 3 parts by weight, or about 0.5 parts by weight, based on 100 parts by weight of the particulate crosslinked polymer.

The step of mixing the silica-introduced particulate crosslinked polymer with a surface crosslinking agent (S132) may be a step of modifying the surface of the crosslinked polymer by contacting the particulate crosslinked polymer with a surface crosslinking solution. The mixing may be performed using a mixer.

The surface crosslinking agent is not particularly limited as long as it is a material capable of modifying the surface of the crosslinked polymer through a solvent. For example, a surface crosslinking component such as a condensation reactive surface crosslinking material, an ionic surface crosslinking material, or a mixture thereof, and water and/or Or it may include a solvent such as ethanol.

Examples of the condensation-reactive surface crosslinking material include polyhydric alcohol compounds such as alkyl diol, alkylene glycol, alkyl diglycidyl ether, alkylene glycol diglycidyl ether, alkylene carbonate compounds, epoxy compounds, polyamine compounds , A haloepoxy compound, an oxazoline compound, or a mixture thereof, and examples of the ionic surface crosslinking material include a polyvalent metal salt. The surface crosslinking agent may be mixed in an amount of about 0.01 to 10 parts by weight based on 100 parts by weight of the particulate crosslinked polymer. In an exemplary embodiment, the surface crosslinking agent may include about 0.5 parts by weight of ethylene carbonate, about 1 part by weight of aluminum sulfate, and 5 parts by weight of water based on 100 parts by weight of the particulate crosslinked polymer.

The step of heat-treating the particulate crosslinked polymer mixed with the surface crosslinking agent (S133) may be a step of heating the crosslinked polymer to accelerate the reaction between the surface crosslinking agent and the crosslinked polymer. The heating may be performed using a hot air dryer, fluid bed dryer, air flow dryer, infrared dryer, or dielectric heating dryer, but is not limited thereto. In an exemplary embodiment, the step of heat-treating the particulate crosslinked polymer mixed with the surface crosslinking agent (S133) may be performed for a shorter time than the step of drying the particulate crosslinked polymer (S122). For example, the heat treatment may be performed at a temperature in the range of about 100° C. to 200° C., or about 150° C. to 180° C. for a time in the range of about 10 minutes to 80 minutes, or about 20 minutes to 70 minutes, or about 25 minutes to 40 minutes Can be done.

The surface crosslinking agent may react with the non-crosslinked linear polymer chain on the surface of the particulate crosslinked polymer to reduce the water-soluble component and residual monomer content of the crosslinked polymer. In addition, the water-retaining ability of the water absorbent resin may be improved due to the hydrophilic alkylene oxy group.

Subsequently, the surface crosslinked particulate crosslinked polymer is classified (S200). The classification means classifying the particulate crosslinked polymer into a particulate crosslinked polymer having a specific particle size or more and a particulate crosslinked polymer having a particle size less than the specific particle size. In an exemplary embodiment, the step of classifying the surface crosslinked particulate crosslinked polymer (S200) may be a step of classifying a first particulate crosslinked polymer having a particle size of 150 μm or more and a second particulate crosslinked polymer having a particle size of less than 150 μm, but is limited thereto. It is not possible to classify based on 300㎛, or may be classified based on 150㎛ and 300㎛. The classification may be performed using a sieve or a dust collector.

Then, the classified first particulate crosslinked polymer, second particulate crosslinked polymer, and binder are mixed (S300). The step of mixing the first and second particulate crosslinked polymers and the binder (S300) includes mixing the first particulate crosslinked polymer having a relatively large particle size, a second particulate crosslinked polymer having a relatively small particle size, and a binder to obtain the second It may be a step of bonding at least part of the particulate crosslinked polymer to the surface of the first particulate crosslinked polymer. Through this, it is possible to improve the absorption rate of the water absorbent resin by forming voids between the plurality of particulate crosslinked polymers bound and increasing the surface area of the water absorbent resin.

In an exemplary embodiment, the second particulate crosslinked polymer having a particle size of less than 150 μm is about 1% by weight or more and about 10% by weight based on the total weight of the total particulate crosslinked polymer including the first particulate crosslinked polymer and the second particulate crosslinked polymer. It may be included in the following range. If the ratio of the second particulate crosslinked polymer is 1% by weight or more, it may exhibit an effect of improving the absorption rate, and if it is 10% by weight or less, it may have a sufficient degree of water holding capacity, absorption capacity under pressure, or liquid permeability despite adhesion of fine powder, It is possible to minimize the amount of fine powder that remains without adhesion or that is re-desorbed after adhesion.

The binder is not particularly limited as long as it is a material capable of physically and/or chemically bonding the particles and the particles. In an exemplary embodiment, the binder may be a binder solution containing a cationic binder material. By applying a cationic binder material as a binder, it is possible to improve the permeability of the water absorbent resin. Examples of the cationic binder material include polyvinylamine. The content of the cationic binder material in the binder solution may be appropriately selected so as to exhibit a binding effect, but may be included in a range of, for example, about 25% by weight or more and 50% by weight or less based on the total weight of the binder solution. In another embodiment, the binder may be distilled water.

In addition, about 2 to 5 parts by weight of the binder may be mixed with respect to 100 parts by weight of the total particulate crosslinked polymer including the first particulate crosslinked polymer and the second particulate crosslinked polymer. In the examples in which the ratio of the second particulate crosslinked polymer is 1% by weight or more and 10% by weight or less, if the content of the binder is 2 parts by weight or more, the content of fine powder remaining without being bonded can be minimized, and if it is 5 parts by weight or less, the water absorbent resin The liquid permeability of the can be prevented from deteriorating.

Although not shown in the drawings, a step of drying after the step (S300) of mixing the first particulate crosslinked polymer, the second particulate crosslinked polymer, and the binder may be further included.

Meanwhile, in some embodiments, the step of classifying the surface crosslinked particulate crosslinked polymer (S200) may be omitted. In this case, as a particulate crosslinked polymer comprising a plurality of particles, a particulate crosslinked polymer having an internal network structure and surface crosslinked is prepared (S100), and the surface crosslinked particulate crosslinked polymer is mixed with a binder in an unclassified state to form one Particles and other particles can be combined.

Hereinafter, a super absorbent polymer according to embodiments of the present invention will be described.

2 is a schematic diagram showing a particle shape of a super absorbent polymer according to an embodiment of the present invention.

Referring to FIG. 2, one particle 1010 of a particulate superabsorbent resin including a plurality of particles is a first sub-particle 110, a cationic binder layer coated on at least a part of the surface of the first sub-particle 110 (300) and the second sub-particle 210 directly bonded to the binder layer 300. In an exemplary embodiment, the binder layer 300 may include polyvinylamine. The first sub-particle 110 and the second sub-particle 210 may be one surface crosslinked particulate crosslinked polymer separated by physical impact, but is not limited thereto, and the first sub-particle 110 and the second sub-particle 110 The sub-particles 210 may be derived from different surface crosslinked particulate crosslinked polymers. The first sub-particle 110 may have a particle size of 150 μm or more, and the second sub-particle 210 may have a particle size of less than 150 μm, but the present invention is not limited thereto.

The first sub-particle 110 may be a crosslinked polymer particle having an internally crosslinked network structure. The first sub-particles 110 may have a partially different crosslinking density. In an exemplary embodiment, the first sub-particle 110 has a uniform internal crosslinking density as a whole and a first portion 111 having a relatively low crosslinking density, and an agent having a relatively high crosslinking density compared to the first portion 111. Includes two parts 112.

The average crosslinking density in the first portion 111 may be approximately uniform. The second portion 112 may have an average crosslinking density higher than that of the adjacent first portion 111. For example, the average crosslinking density in the second portion 112 may gradually increase in a direction away from the first portion 111. 2 illustrates a case where the second part 112 surrounds only a part of the first part 111, but is not limited thereto, and the second part 112 may completely surround the first part 111 have.

Meanwhile, the second sub-particle 210 may be a crosslinked polymer particle having an internal network structure. The second sub-particles 210 may have partially different crosslinking densities. In an exemplary embodiment, the second sub-particle 210 has a uniform internal crosslinking density as a whole and a first portion 211 having a relatively low crosslinking density, and an agent having a relatively high crosslinking density compared to the first portion 211. Includes two parts 212.

The average crosslinking density in the first portion 211 may be approximately uniform. The second portion 212 may have an average crosslinking density greater than that of the adjacent first portion 211. For example, the average crosslinking density in the second portion 212 may gradually increase in a direction away from the first portion 211.

The binder layer 300 may be a coating layer formed on the surface of the first sub-particle 110 and/or the second sub-particle 210. In the present specification, the coating layer is meant to include not only a layer surrounding the target surface in the form of a thin film including a dispersion medium and a dispersant, but also a layer attached by remaining on the target surface by removing the dispersion medium. . 2 illustrates a case where the binder layer 300 completely surrounds the first sub-particles 110 and the second sub-particles 210, but is not limited thereto, and the binder layer 300 includes a first sub-particle ( 110) and the second sub-particle 210 may be formed only on a portion of the surface.

The binder layer 300 may combine the first sub-particles 110 and the second sub-particles 210. Specifically, the first sub-particle 110 and the second sub-particle 210 are mutually bonded through the binder layer 300, but the second part 112 and the second sub-particle of the first sub-particle 110 The second portion 212 of 210 may be combined.

3 is a schematic diagram showing a particle shape of a super absorbent polymer according to another embodiment of the present invention.

Referring to FIG. 3, one particle 1020 of the particulate superabsorbent polymer including a plurality of particles according to the embodiment of FIG. 3 is a second portion 122 and a second sub particle of the first sub particle 120. The point that the second portion 222 of 220 partially abuts and bonds to each other is different from the one particle 1010 according to the embodiment of FIG. 2.

In this case, one particle 1020 is a portion in which the crosslinking density gradually increases along one direction (ie, the second portion 122 of the first sub-particle) and a portion in which the crosslinking density gradually decreases in the one direction (In other words, the second portion 222 of the second sub-particle may include an area sequentially adjacent to each other. In other words, one particle 1020 may at least partially include a portion that changes so that the size of the crosslinking density gradually increases and then gradually decreases.

4 is a schematic diagram showing a particle shape of a super absorbent polymer according to another embodiment of the present invention.

Referring to FIG. 4, one particle 1030 of a particulate superabsorbent resin including a plurality of particles according to the embodiment of FIG. 4 is a first sub-particle 130 and at least a part of the surface of the first sub-particle 130 Including the cationic binder layer 300 and the second sub-particle 230 directly bonded to the binder layer 300 coated on the first sub-particle 130 and the second sub-particle 230 is a binder layer 300 ) Interposed with each other, the point where the second part 132 of the first sub-particle 130 and the first part 231 of the second sub-particle 230 are combined is one according to the embodiment of FIG. It is different from the particle 1010.

5 is a schematic diagram showing a particle shape of a super absorbent polymer according to another embodiment of the present invention.

Referring to FIG. 5, one particle 1040 of the particulate superabsorbent polymer including a plurality of particles according to the embodiment of FIG. 5 is a second portion 142 and a second sub particle of the first sub particle 140. The point that the first portion 241 of 240 partially abuts and bonds to each other is different from the one particle 1030 according to the embodiment of FIG. 4.

In this case, one particle 1040 is greater than the maximum crosslinking density of the portion where the crosslinking density gradually increases along one direction (that is, the second portion 142 of the first subparticle) and the portion where the crosslinking density gradually increases. A portion having a small crosslinking density but maintaining a substantially uniform crosslinking density along the one direction (i.e., the first portion 241 of the second subparticle) and a portion where the crosslinking density gradually increases again along the one direction (That is, the second portion 242 of the second sub-particle may include an area in which the second sub-particles are sequentially disposed adjacent to each other. In other words, one particle 1040 may at least partially include a portion that gradually increases in size of the crosslinking density, then rapidly decreases, and then gradually increases again.

6 is a schematic diagram showing a particle shape of a super absorbent polymer according to another embodiment of the present invention.

Referring to FIG. 6, one particle 1050 of a particulate super absorbent polymer including a plurality of particles is a second sub-particle 150 and a second sub-particle 150 in direct contact with the surfaces of the first sub-particles 150. Contains particles 250.

The first sub-particle 150 may be a crosslinked polymer particle having an internally crosslinked network structure. The first sub-particles 150 may have partially different crosslinking densities. In an exemplary embodiment, the first sub-particle 150 has a uniform internal crosslinking density as a whole and a first portion 151 having a relatively low crosslinking density, and an agent having a relatively high crosslinking density compared to the first portion 151. Includes two parts 152.

The average crosslinking density in the first portion 151 may be approximately uniform. The second portion 152 may have an average crosslinking density higher than that of the adjacent first portion 151. For example, the average crosslinking density in the second portion 152 may gradually increase in a direction away from the first portion 151.

In addition, the percentage of water contents of the second portion 152 of the first sub-particle 150 may be greater than that of the first portion 151. In an exemplary embodiment, the moisture content of the first portion 151 is approximately uniform, and the moisture content of the second portion 152 may be greater than that of the adjacent first portion 151. For example, the moisture content of the second portion 152 may gradually increase in a direction away from the first portion 151. In the method of manufacturing a superabsorbent polymer according to an embodiment using distilled water as a binder, it may be understood that the distilled water penetrated into the surface of the first sub-particle 150 and contributed to an increase in the moisture content of the second part 152, but the present invention This is not limited to this.

The second sub-particle 250 may be a crosslinked polymer particle having an internally crosslinked network structure. The second sub-particles 250 may have partially different crosslinking densities. In an exemplary embodiment, the second sub-particle 250 is a first portion 251 having a uniform internal crosslinking density and a relatively low crosslinking density, and an agent having a relatively high crosslinking density compared to the first portion 251. Includes two parts 252.

The average crosslinking density in the first portion 251 may be approximately uniform. The second portion 252 may have an average crosslinking density higher than that of the adjacent first portion 251. For example, the average crosslinking density in the second portion 252 may gradually increase in a direction away from the first portion 251.

In addition, the moisture content of the second portion 252 of the second sub-particle 250 may be greater than that of the first portion 251. In an exemplary embodiment, the moisture content of the first portion 251 is approximately uniform, and the second portion 252 may have a higher moisture content than the adjacent first portion 251. For example, the moisture content of the second portion 252 may gradually increase in a direction away from the first portion 251.

The first sub-particle 150 and the second sub-particle 250 may be directly contacted and bonded. In an exemplary embodiment, the second portion 152 of the first sub-particle 150 and the second portion 252 of the second sub-particle 250 may directly contact each other to be coupled. In another embodiment, unlike shown in the drawings, the second portion 152 of the first sub-particle 150 and the first portion 251 of the second sub-particle 250 may directly contact each other to be coupled.

Hereinafter, with reference to Preparation Examples, Comparative Examples, and Experimental Examples, the super absorbent polymer according to the present invention and a method of manufacturing the same will be described in more detail.

< Comparative example >

After mixing 77.778 g of 50% caustic soda solution (NaOH) and 88.84 g of water, 100 g of acrylic acid, 0.050 g of polyethylene glycol diacrylate (Mw=400) as an internal crosslinking agent, 2,2-bis[(acryloxy)methyl]butyl A monomer aqueous solution having a monomer concentration of 45% by weight was prepared by mixing 0.050 g of acrylate (15E0) and 0.033 g of diphenyl (2,4,6-trimethylbenzoyl)-phosphine oxide as a photopolymerization initiator. Then, 1.33 g of potassium persulfate, a thermal initiator, was dissolved in 8.67 g of water, and 3.008 g was mixed with the aqueous monomer solution to prepare a monomer composition.

Thereafter, the monomer composition is introduced through the supply unit of a polymerization reactor consisting of a conveyor belt continuously moving at 40°C, and then irradiated with an irradiation amount of ⁹ mW/cm ² through a UV irradiation device, and photopolymerization is performed for 3 minutes. A phase hydrogel crosslinked polymer was prepared. Then, the hydrogel crosslinked polymer was transferred to a cutter and cut into 2 cm. At this time, the water content of the cut hydrogel polymer was 50% by weight. The cut hydrogel crosslinked polymer was chopped using a meat chopper. Subsequently, the hydrogel crosslinked polymer was dried for 1 hour in a hot air dryer at 180°C, and the dried crosslinked polymer was pulverized with a pin mill. Thereafter, the polymer particles were classified into a standard mesh of ASTM standard to prepare a particulate crosslinked polymer having a particle size of 150 to 850 μm.

After 0.5 g of silica was added to 100 g of the prepared particulate crosslinked polymer and mixed, a surface crosslinking solution containing 0.5 g of ethylene carbonate, 1 g of aluminum sulfate and 5 g of water (DW) was added, and reacted for 30 minutes in a hot air dryer at 180°C. To prepare a surface crosslinked particulate water absorbing resin.

Subsequently, the surface-crosslinked particulate water absorbent resin was once again classified to obtain a particulate water absorbent resin having a particle size of 150 to 600 mu m.

< Manufacturing example 1>

A monomer composition and a particulate crosslinked polymer were prepared in the same manner as in Comparative Example, and a surface crosslinked particulate water absorbing resin was prepared.

Then, the surface crosslinked particulate water absorbing resin was once again classified. Then, 95 g of the particulate water absorbent resin classified to 150 to 600 μm and 5 g of the particulate water absorbent resin classified to less than 150 μm were mixed, 4 g of distilled water was sprayed as a binder, and further mixed, and dried to obtain a particulate water absorbing resin. .

< Manufacturing example 2>

A monomer composition and a particulate crosslinked polymer were prepared in the same manner as in Preparation Example 1, except that an aqueous solution of 1.1 g of polyvinylamine (BASF, Xelorex Rs 1200) and 2.9 g of distilled water was used as a binder, and the surface crosslinked A particulate water absorbent resin was prepared and obtained.

< Manufacturing example 3>

A monomer composition and a particulate crosslinked polymer were prepared in the same manner as in Preparation Example 1, except that an aqueous solution of 1.8 g of polyvinylamine (BASF, Xelorex Rs 1200) and 2.2 g of distilled water was used as a binder, and surface crosslinked A particulate water absorbent resin was prepared and obtained.

< Experimental example 1: particle size distribution measurement>

The particulate water-absorbing resin obtained according to Preparation Examples and Comparative Examples was once again classified, and then the weight% by particle size relative to the total weight was measured, and the results are shown in Table 1 below.

Particle size (㎛) >850 850-600 600-300 300-150 <150 Comparative example 0 0.04 71.89 28.07 0 Manufacturing Example 1 0.47 1.93 72.30 23.93 1.36 Manufacturing Example 2 0.40 1.39 72.71 24.68 0.83 Manufacturing Example 3 0.45 1.66 72.90 23.71 1.28

Referring to Table 1, in the case of the water absorbent resins of Preparation Examples 1 to 3 in which fine powders having a particle size of 150 μm or less are attached to a particulate water absorbent resin having a particle size of 150 to 600 μm or less, particles having a particle size of 600 μm or more It can be seen that the increased to 2.4% by weight, 1.79% by weight, and 2.11% by weight, respectively.

< Experimental example 2: Measurement of physical properties>

The absorption rate (Free Swelling Rate, FSR), liquid permeability (Gel Bed Permeability, GBP), Centrifuge Retention Capacity (CRC), and Absorption Under Pressure of the particulate water-absorbing resin obtained according to Preparation Examples and Comparative Examples , AUP) was measured and the results are shown in Table 2 below.

The absorption rate was quantified according to the vortex time measurement method by dividing the particle size of 150 to 600 μm and 300 to 600 μm. In addition, measurement of liquid permeability was performed under atmospheric pressure. The measurement of water holding capacity was performed according to the EDANA (European Disposables and Nonwovens Association) WSP 241.2 method by dividing the case where the saline was absorbed for 20 seconds and the case where it was absorbed for 30 minutes. In addition, the measurement of the absorption capacity under pressure was performed according to the EDANA 242.2 method.

Absorption rate (g/g·s) Liquid permeability (darcy)
(600-300㎛) Water holding capacity (g/g) Absorption capacity under pressure (g/g)
(600-300㎛) 600-150㎛ 600-300㎛ 20 sec (600-150㎛) 30 min (600-300㎛) Comparative example 0.4 0.38 29.5 17 34 21 Manufacturing Example 1 0.5 0.42 24.5 19 33 21 Manufacturing Example 2 1.00 0.74 34.5 19 32 20 Manufacturing Example 3 1.18 1.22 32 19 34 21

Referring to Table 2, the water absorbent resins of Preparation Examples 1 to 3 have the same or better water holding capacity and water absorption capacity under pressure as the water absorbent resin of Comparative Example even though fine powder having a particle size of 150 μm or less is attached. I can confirm.

In addition, it can be seen that the water absorbent resin according to Preparation Example 2 and Preparation Example 3 has better liquid permeability than the water absorbent resin according to Comparative Example.

In addition, it can be seen that the water absorbent resin according to Preparation Examples 1 to 3 has an improved absorption rate compared to the water absorbent resin according to the Comparative Example.

The embodiments of the present invention have been described above, but these are only examples and do not limit the present invention, and those of ordinary skill in the field to which the present invention pertains should not depart from the essential characteristics of the embodiments of the present invention. It will be appreciated that various modifications and applications not illustrated above are possible. For example, each component specifically shown in the embodiments of the present invention can be modified and implemented. And differences related to these modifications and applications should be construed as being included in the scope of the present invention defined in the appended claims.

110: first sub-particle
210: second sub-particle
300: binder layer

Claims (14)

A particulate crosslinked polymer comprising a plurality of particles, comprising: preparing a particulate crosslinked polymer having an internal network structure and crosslinked on the surface;
Classifying the surface crosslinked particulate crosslinked polymer into a first particulate crosslinked polymer and a second particulate crosslinked polymer having a particle size smaller than that of the first particulate crosslinked polymer; And
Mixing the first particulate crosslinked polymer, the second particulate crosslinked polymer, and a binder to combine one particle and another particle,
The step of preparing a particulate crosslinked polymer having an internal network structure and crosslinked on the surface,
Polymerizing a hydrophilic monomer composition to prepare a hydrogel crosslinked polymer,
Pulverizing the hydrogel crosslinked polymer, and
And surface crosslinking the pulverized particulate crosslinked polymer,
The particle size of the first particulate crosslinked polymer is 150 μm or more and 600 μm or less, and the particle size of the second particulate crosslinked polymer is less than 150 μm,
In the step of bonding the first particulate crosslinked polymer and the second particulate crosslinked polymer, the first particulate crosslinked polymer is 95 parts by weight or more, and the second particulate crosslinked polymer is mixed in less than 5 parts by weight of the super absorbent polymer. Manufacturing method. delete The method of claim 1,
The step of surface crosslinking the particulate crosslinked polymer,
Mixing the pulverized particulate crosslinked polymer with a silica-based material,
Mixing the crosslinked polymer mixed with the silica-based material with a surface crosslinking agent, and
A method for producing a super absorbent polymer comprising the step of heat-treating the crosslinked polymer mixed with the surface crosslinking agent. delete The method of claim 1,
The step of mixing the particulate crosslinked polymer and the binder is a step of mixing 2 to 5 parts by weight of the binder based on 100 parts by weight of the particulate crosslinked polymer. The method of claim 5,
The particulate crosslinked polymer includes a first particulate crosslinked polymer having a particle size of 150 μm or more and a second particulate crosslinked polymer having a particle size of less than 150 μm,
In the step of mixing the particulate crosslinked polymer and the binder, the second particulate crosslinked polymer is included in a range of 1% by weight to 10% by weight based on the total weight of the particulate crosslinked polymer. The method of claim 1,
The binder is distilled water, a method for producing a super absorbent polymer. The method of claim 1,
The binder is a method for producing a super absorbent polymer, which is a binder solution containing a cationic binder material. As a particulate super absorbent polymer comprising a plurality of particles,
One of the particles,
A first sub-particle having an internally crosslinked network structure, but partially different in crosslinking density; And
The second sub-particles are bonded to the first sub-particles, have an internally cross-linked network structure, and have a partially different cross-linking density,
The crosslinking density of the portion of the first subparticle bonded to the second subparticle is greater than the crosslinking density inside the first subparticle,
The particle size of the first sub-particle is 150 μm or more and 600 μm or less, and the particle size of the second sub-particle is less than 150 μm,
The first sub-particles are included in 95 parts by weight or more, and the second sub-particles are included in less than 5 parts by weight of the super absorbent polymer. The method of claim 9,
The one particle, the super absorbent polymer further comprises a binder layer interposed between the first sub-particle and the second sub-particle to bond the first sub-particle and the second sub-particle. The method of claim 10,
The binder layer is a super absorbent polymer comprising a cationic material. The method of claim 9,
The water content of the portion of the first sub-particles bonded to the second sub-particles is greater than the water content of the inside of the first sub-particles. delete delete

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