WO2016200054A1 - Super-absorbent resin and method for preparing same - Google Patents

Abstract

The present invention relates to a super-absorbent resin and a method for preparing the same. In the super-absorbent resin of the present invention, the gel strength index of equation 1 below is 0.5 or more. [Equation 1] Gel strength index = 0.7 psi AUP of super-absorbent resin / CRC of base polymer, wherein, in equation 1, 0.7 psi AUP (g/g) is the value of absorbency under pressure analyzed according to the EDANA WSP242.2.R3, and CRC of the base polymer (g/g) is the value of centrifuge retention capacity obtained by analyzing CRC of the base polymer before surface cross-linking according to the EDANA WSP241.2.R3.

Description

Super Absorbent Resin and Manufacturing Method Thereof

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

Super Absorbent Polymer (SAP) is a synthetic polymer material capable of absorbing water of 500 to 1,000 times its own weight.As a developer, super absorbent material (SAM) and absorbent gel material (AGM) They are named differently. Such super absorbent polymers have been put into practical use as physiological tools, and nowadays, in addition to hygiene products such as children's paper diapers, horticultural soil repair agents, civil engineering, building index materials, seedling sheets, freshness-retaining agents, and steaming in the food distribution sector. It is widely used as a material for articles.

As a method for producing such a super absorbent polymer, a method by reverse phase suspension polymerization or a method by aqueous solution polymerization is known. Reverse phase suspension polymerization is disclosed in, for example, Japanese Patent Laid-Open Nos. 56-161408, 57-158209, and 57-198714. As the method by aqueous solution polymerization, a thermal polymerization method for applying polymerization to an aqueous solution and polymerizing it again, and a photopolymerization method for irradiating and polymerizing ultraviolet rays or the like are known.

The problem to be solved by the present invention is to provide a superabsorbent polymer having excellent gel strength and excellent permeability, and to provide a method for producing such a superabsorbent polymer.

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

The superabsorbent polymer according to an embodiment of the present invention for solving the above problems may have a gel strength index of 0.5 or more.

[Equation 1]

Gel strength indicator = CRC of 0.7 psi AUP / base polymer of superabsorbent polymer

In Formula 1, the 0.7 psi AUP (g / g) is a pressure absorbency value analyzed according to the EDANA WSP242.2.R3 method, and the CRC (g / g) of the base polymer is determined according to the EDANA WSP241.2.R3 method. It is the water retention value which analyzed CRC of base polymer before surface crosslinking.

0.7psi pressure absorption capacity (AUP) of the superabsorbent polymer may range from 20 g / g to 30 g / g.

The water holding capacity (CRC) of the base polymer may range from 40 g / g or less.

The water retention capacity (CRC) according to the EDANA WSP241.2.R3 method of the superabsorbent polymer may be in the range of 30 g / g or less.

The superabsorbent polymer may have a gel layer permeability (GBP) of 30 × 10 ⁻⁸ cm 2 or more, as measured by a Free Swell Gel Bed Permeability Test.

The super absorbent polymer may include at least one of a polyvalent cationic metal and an inorganic powder.

The polyvalent cation metal may include aluminum sulfate, aluminum lactate or aluminum phosphate.

The inorganic powder may include silicon dioxide, aluminum silicate oxide, magnesium oxide, zinc oxide, zeolite, bentonite or kaolin.

The superabsorbent polymer manufacturing method according to an embodiment of the present invention for solving the above problems is a step of polymerizing a monomer composition into a base polymer, pulverizing the base polymer, a polyvalent cation metal or inorganic powder on the ground base polymer Mixing a surface, and surface crosslinking the base polymer.

The mixing step and the surface crosslinking step may be performed at the same time.

The surface crosslinking may be performed after the mixing.

The polymerization may include a monomer composition, an initiator, and a crosslinking agent, and the crosslinking agent may be included in a range of 0.05 part by weight to 1 part by weight with respect to the monomer composition.

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

According to embodiments of the present invention has at least the following effects.

The superabsorbent polymer of the present invention may have excellent gel strength while having excellent gel bed permeability.

In addition, the superabsorbent polymer production method of the present invention can produce a superabsorbent polymer having excellent gel strength and gel permeability as described above.

The effects according to the present invention are not limited by the contents exemplified above, and more various effects are included in the present specification.

1 to 3 are schematic diagrams showing an apparatus for measuring gel permeability according to an embodiment of the present invention.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms. It is provided to fully convey the scope of the invention to those skilled in the art, the invention being defined only by the scope of the claims. Like reference numerals refer to like elements throughout. In the drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity.

Manufacturing method of super absorbent polymer

Method for producing a super absorbent polymer according to an embodiment of the present invention comprises the steps of polymerizing a monomer composition to a base polymer, pulverizing the polymerized base polymer, mixing a polyvalent cationic metal or inorganic powder to the ground base polymer And surface crosslinking the base polymer.

Although the step of polymerizing the super absorbent polymer is not particularly limited, the monomer composition may be injected into the polymerization reactor and polymerized. For efficient processing, the polymerization can be carried out continuously using a continuous polymerization reactor. In this case, in order to form superabsorbent resin, although the said monomer composition can be inject | poured and superposed | polymerized on a belt, it is not limited only to this.

As the monomer contained in the monomer composition, the water-soluble ethylenically unsaturated monomer can be used without limitation as long as it is a monomer generally used in the production of superabsorbent polymers. The monomer can be used at least one selected from the group consisting of anionic monomers and salts thereof, nonionic hydrophilic containing monomers, amino group-containing unsaturated monomers and quaternized compounds thereof.

In an exemplary embodiment, acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, 2-acryloylethane sulfonic acid, 2-methacryloylethanesulfonic acid, 2- (meth) acryloylpropanesulfonic acid And 2- (meth) acrylamide-2-methylpropanesulfonic acid; at least one anionic monomer or salt thereof; (Meth) acrylamide, N-substituted (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, methoxy polyethylene glycol (meth) acrylate and polyethylene glycol ( One or more nonionic hydrophilic-containing monomers selected from the group consisting of meth) acrylates; Or one or more amino group-containing unsaturated monomers selected from the group consisting of (N, N) -dimethylaminoethyl (meth) acrylate and (N, N) -dimethylaminopropyl (meth) acrylamide, or quaternized products thereof. can do.

The concentration of the water-soluble ethylenically unsaturated monomer in the monomer composition depends on the polymerization time and reaction conditions (feed rate of the monomer composition, irradiation time of heat and / or light, irradiation range, and irradiation strength, belt width, length and moving speed, etc.). Although appropriately selected and used in consideration, in an exemplary embodiment, it may range from 40 to 60% by weight. In this case, it may be efficient in terms of solubility and economics of the monomer.

The monomer composition may further include an initiator, a crosslinking agent, and the initiator may be a photopolymerization initiator, a thermal polymerization initiator or a redox initiator. The initiator may be used by appropriately selecting the type according to whether to select thermal polymerization, photopolymerization, polymerization due to redox reaction, or thermal polymerization and photopolymerization in the process.

The photopolymerization initiator is not particularly limited, but for example, diethoxy acetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 4- (2-hydroxy ethoxy) phenyl- ( Acetophenone derivatives such as 2-hydroxy) -2-propyl ketone and 1-hydroxycyclohexylphenyl ketone; Benzoin alkyl ether compounds such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; benzophenone derivatives such as methyl o-benzoyl benzoate, 4-phenyl benzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, and (4-benzoyl benzyl) trimethylammonium chloride; Thioxanthone compounds; Acyl phosphine oxide derivatives such as bis (2,4,6-trimethylbenzoyl) -phenyl phosphine oxide and diphenyl (2,4,6-trimethylbenzoyl) -phosphine oxide; Or azo systems such as 2-hydroxy methyl propionitrile and 2,2 '-(azobis (2-methyl-N- (1,1'-bis (hydroxymethyl) -2-hydroxyethyl) propion amide) Although a compound etc. can be used 1 type or in mixture of 2 or more types, It is not limited to these.

Although the thermal polymerization initiator is not particularly limited, for example, an azo initiator, a peroxide initiator, a redox initiator or an organic halide initiator may be used alone or in combination of two or more thereof. have. In addition, sodium persulfate (Na ₂ S ₂ O ₈ ) or potassium persulfate (Potassium persulfate, K ₂ S ₂ O ₈ ) among the thermal polymerization initiators may be mentioned, but is not limited thereto.

In the monomer composition, the content of the photopolymerization initiator and the thermal polymerization initiator can be selected as long as it can exhibit the polymerization initiation effect. In an exemplary embodiment, the photopolymerization initiator may be included in the range of 0.005 to 0.1 parts by weight based on 100 parts by weight of the monomer, and the thermal polymerization initiator may be included in the range of 0.01 to 0.5 parts by weight based on 100 parts by weight of the monomer, but is not limited thereto. no.

The crosslinking agent includes at least one functional group capable of reacting with the substituent of the monomer and at least one ethylenically unsaturated group, or two or more functional groups capable of reacting with the substituent of the monomer and / or with the substituent formed by hydrolyzing the monomer. Crosslinking agents can be used.

In an exemplary embodiment, the crosslinking agent is a poly (meth) acrylate of a polyol having 8 to 12 carbon atoms, a bismethacrylamide having 8 to 12 carbon atoms, a polyol having 2 to 10 carbon atoms or a poly (poly) having a polyol having 2 to 10 carbon atoms. Meta) allyl ether, and the like, and more specific examples thereof include N, N'-methylenebis (meth) acrylate, ethyleneoxy (meth) acrylate, polyethyleneoxy (meth) acrylate, and propyleneoxy (meth) acryl. Glycerol diacrylate, glycerin triacrylate, trimethol triacrylate, triallylamine, triarylcyanurate, triallyl isocyanate, polyethylene glycol, diethylene glycol, propylene glycol, or mixtures of two or more thereof Although these are mentioned, It is not limited only to these.

In the monomer composition, if the crosslinking agent can exhibit a crosslinking effect, its content can be selected and used. In an exemplary embodiment, the crosslinking agent may be included in the range of 0.05 to 1 parts by weight based on 100 parts by weight of the monomer composition. By satisfying the above range, it is possible to have excellent gel strength and at the same time increase the gel layer fluidity.

On the other hand, the base polymer is completed polymerization may be subjected to the step of grinding. The pulverizing may be performed by inserting a base polymer having completed polymerization into a cutting device and cutting it by a cutter. In this case, the cutter can cut the base polymer into patterned pieces.

The cut base polymer may further include grinding, drying and further grinding the dried polymer. In some cases, before the milling step, a temporary drying step may be further included to prevent agglomeration and the like in the milling step.

Although it does not specifically limit as a grinding | pulverization method, For example, the apparatus which cuts and extrudes a rubbery elastic body can be used. In an exemplary embodiment, cutter type cutters, chopper type cutters, kneader type cutters, vibratory grinders, impact grinders, friction grinders, and the like can be cited, but not limited thereto.

As a drying method, a dryer and a heating furnace can be used normally. In an exemplary embodiment, hot air dryers, fluidized bed dryers, airflow dryers, infrared dryers, dielectric heating dryers, and the like may be mentioned, but are not limited thereto. The drying temperature is not particularly limited, but may be in the range of 100 to 200 for preventing thermal degradation and for efficient drying.

Next, the step of mixing the polyvalent cationic metal or inorganic powder with the ground base polymer. Agglomeration of the superabsorbent polymer produced by mixing the polyvalent cationic metal or the inorganic powder can be prevented, whereby the liquid permeability of the superabsorbent polymer can be improved.

The polyvalent cation metal may include aluminum sulfate, aluminum lactate or aluminum phosphate, and the inorganic powder may include silicon dioxide, aluminum silicate oxide, magnesium oxide, zinc oxide, zeolite, bentonite or kaolin, but is not limited thereto. It is not.

Meanwhile, the step of mixing the polyvalent cation metal or inorganic powder and the step of surface crosslinking may be performed at the same time, but are not limited thereto. The order can be changed as appropriate.

Next, a step of crosslinking the surface of the base polymer may be performed. The surface crosslinking step may be performed using, for example, ethylene glycol diglycidyl ether, water, and ethanol, but is not limited thereto.

The surface crosslinking step may be performed by mixing a surface crosslinking solution including any one or more of the crosslinking agent, the polyvalent cation metal, and the inorganic powder with the base polymer, and further, by drying the surface crosslinked base polymer, A water absorbent resin can be manufactured. The surface-crosslinked base polymer may be dried by a hot air oven, but is not limited thereto.

In addition, the prepared base polymer may further include the step of preparing a superabsorbent polymer having a particle diameter of 150 μm or more to 850 μm or less using a mesh.

Super Absorbent Resin Particles

The super absorbent polymer according to an embodiment of the present invention may have a gel strength index of 0.5 or more, for example, 0.5 to 0.8, 0.5 to 0.75, or 0.55 to 0.71. It is possible to provide excellent permeability while maintaining the excellent gel strength of the super absorbent polymer in the range of the gel strength index.

[Equation 1]

Gel strength indicator = CRC of 0.7 psi AUP / base polymer of superabsorbent polymer

In Formula 1, the 0.7 psi AUP (g / g) is a pressure absorbency value analyzed according to the EDANA WSP242.2.R3 method, and the CRC (g / g) of the base polymer is determined according to the EDANA WSP241.2.R3 method. It is the water retention value which analyzed CRC of base polymer before surface crosslinking.

In addition, the 0.7psi pressure absorption capacity (AUP) of the superabsorbent polymer may range from 20 g / g to 30 g / g, for example, from 20 g / g to 25 g / g or from 21 g / g to 24 g / g. Can be. In the case of the pressure absorbing ability, the higher the surface crosslinking density as the ability to absorb water under a certain pressure, the higher the ability to absorb water even under pressure. The superabsorbent polymer of the present invention may have an excellent absorbency by satisfying the pressure absorbency range.

In addition, the water holding capacity (CRC) of the base polymer may be in the range of 40g / g or less, for example, more than 0g / g to 40g / g, 20g / g to 40g / g, or 30g / g to 40g It may range from / g. The water-retaining ability means that when the internal crosslinking degree is increased and the ability to hold the liquid is low, the numerical value is low, and the gel strength of the base polymer is relatively increased. When satisfying the range of the value of the gel strength index while satisfying the water holding range of the base polymer of the present invention, it may have excellent permeability and water absorption while maintaining excellent gel strength.

In other words, the superabsorbent polymer of the present invention can increase the crosslinking degree of the base polymer to increase the strength of the superabsorbent resin, and the surface of the base polymer includes a polyvalent metal salt or an inorganic material, thereby forming a channel through which liquid can flow. The permeability can be improved.

On the other hand, water retention capacity (CRC) according to the EDANA WSP241.2.R3 method of the super absorbent polymer may be in the range of 30g / g or less. By satisfying the above range, both the inside and the outside of the super absorbent polymer can have a gel strength of a predetermined level or more, so that high gel layer fluidity can be obtained.

Gel layer liquid permeability (GBP) of the super absorbent polymer may be in the range of 30 × 10 ^-8 cm 2 or more, for example, 30 × 10 ^-8 cm 2 to 80 × 10 ^-8 cm 2 or 35 × 10 ^-8 cm 2 to May range from 75 × 10 ⁻⁸ cm 2. That is, as described above, by adjusting the CRC value of the base polymer and the AUP value of the super absorbent polymer, the gel strength index may be satisfied within a predetermined numerical range, thereby satisfying the gel layer fluidity value as described above. have.

On the other hand, as described in the manufacturing method of the super absorbent polymer, the super absorbent polymer may include at least one or more of a polyvalent cationic metal and an inorganic powder. As described above, the permeability can be improved by using any one of a polyvalent cationic metal and an inorganic powder for the surface crosslinking while increasing the crosslinking degree of the base polymer to increase the strength of the super absorbent polymer. On the other hand, the polyvalent cationic metal and the inorganic powder has already been described, a detailed description thereof will be omitted.

Production Example  One

After mixing 77.78 g of 50% aqueous sodium hydroxide solution (NaOH) and 88.84 g of water, 100 g of acrylic acid, 0.08 g of polyethylene glycol diacrylate as a crosslinking agent, diphenyl (2,4,6-trimethylbenzoyl) -phosphine jade as a UV initiator 0.033 g of the seed was mixed to prepare a monomer composition having a concentration of 45% by weight of the hydrophilic monomer.

Thereafter, the monomer composition was added to the polymerizer, and then irradiated with ultraviolet rays through a UV irradiation apparatus, and UV polymerization was performed to prepare a hydrous gel polymer. The hydrogel polymer was transferred to a cutter and then cut. After chopping the gel polymer with a meat chopper, the hydrous gel polymer was dried in a hot air dryer at 180 ° C. for 30 minutes, and the dried hydrogel polymer was ground with a grinder.

Production Example  2

Except for changing the content of polyethylene glycol diacrylate to 0.12g, it is prepared in the same manner as in Preparation Example 1.

Production Example  3

Except for changing the content of polyethylene glycol diacrylate to 0.16g, it is prepared in the same manner as in Preparation Example 1.

Preparation Example 4

Except for changing the content of polyethylene glycol diacrylate to 0.2g, it is prepared in the same manner as in Preparation Example 1.

Comparative example  One

100 g of the base polymer obtained in Preparation Example 1 was mixed with a surface crosslinking solution consisting of 1 g of ethylene carbonate and 4 g of water, and then reacted in a hot air oven at 180 ° C. for 30 minutes. Subsequently, a surface treated superabsorbent polymer having a particle diameter of 150 μm or more and 850 μm or less was prepared using a sieve.

Comparative example  2

100 g of the base polymer obtained in Preparation Example 1 was mixed with a surface crosslinking solution consisting of 1 g of ethylene carbonate, 4 g of water, and 1 g of aluminum sulfate, and then reacted in a hot air oven at 180 ° C. for 30 minutes. Subsequently, a surface treated superabsorbent polymer having a particle diameter of 150 μm or more and 850 μm or less was prepared using a sieve.

Comparative example  3

100 g of the base polymer obtained in Preparation Example 1 was mixed with a surface crosslinking solution consisting of 1 g of ethylene carbonate, 4 g of water, 1 g of aluminum sulfate, and 0.5 g of Silica (Aerosil 200), followed by reaction at a hot air oven at 180 ° C. for 30 minutes. Subsequently, a surface treated superabsorbent polymer having a particle diameter of 150 μm or more and 850 μm or less was prepared using a sieve.

Comparative example  4

100 g of the base polymer obtained in Preparation Example 2 was mixed with a surface crosslinking solution consisting of 1 g of ethylene carbonate, 4 g of water, and 1 g of aluminum sulfate, and then reacted in a hot air oven at 180 ° C. for 30 minutes. Subsequently, a surface treated superabsorbent polymer having a particle diameter of 150 μm or more and 850 μm or less was prepared using a sieve.

Comparative example  5

100 g of the base polymer obtained in Preparation Example 2 was mixed with a surface crosslinking solution consisting of 1 g of ethylene carbonate, 4 g of water, 1 g of aluminum sulfate, and 0.5 g of Silica (Aerosil 200), followed by reaction in a hot air oven at 180 ° C. for 30 minutes. Subsequently, a surface treated superabsorbent polymer having a particle diameter of 150 μm or more and 850 μm or less was prepared using a sieve.

Comparative example  6

100 g of the base polymer obtained in Preparation Example 3 was mixed with a surface crosslinking solution consisting of 1 g of ethylene carbonate and 4 g of water, and then reacted in a hot air oven at 180 ° C. for 30 minutes. A surface treated superabsorbent polymer having a particle diameter of 150 μm or more and 850 μm or less was prepared using a sieve.

Example  One

100 g of the base polymer obtained in Preparation Example 3 was mixed with a surface crosslinking solution consisting of 1 g of ethylene carbonate, 4 g of water, and 1 g of aluminum sulfate, and then reacted in a hot air oven at 180 ° C. for 30 minutes. Subsequently, a surface treated superabsorbent polymer having a particle diameter of 150 μm or more and 850 μm or less was prepared using a sieve.

Example  2

100 g of the base polymer obtained in Preparation Example 3 was mixed with a surface crosslinking solution consisting of 1 g of ethylene carbonate, 4 g of water, 1 g of aluminum sulfate, and 0.5 g of Silica (Aerosil 200), followed by reaction at a hot air oven at 180 ° C. for 30 minutes. Subsequently, a surface treated superabsorbent polymer having a particle diameter of 150 μm or more and 850 μm or less was prepared using a sieve.

Example  3

100 g of the base polymer obtained in Preparation Example 4 was mixed with a surface crosslinking solution consisting of 1 g of ethylene carbonate, 4 g of water, and 1 g of aluminum sulfate, and then reacted in a hot air oven at 180 ° C. for 30 minutes. Subsequently, a surface treated superabsorbent polymer having a particle diameter of 150 μm or more and 850 μm or less was prepared using a sieve.

Example  4

100 g of the base polymer obtained in Preparation Example 4 was mixed with a surface crosslinking solution consisting of 1 g of ethylene carbonate, 4 g of water, 1 g of aluminum sulfate, and 0.5 g of Silica (Aerosil 200), followed by reaction at a hot air oven at 180 ° C. for 30 minutes. Subsequently, a surface treated superabsorbent polymer having a particle diameter of 150 μm or more and 850 μm or less was prepared using a sieve.

Example  5

100 g of the base polymer obtained in Preparation Example 4 was mixed with a surface crosslinking solution consisting of 1 g of ethylene carbonate, 4 g of water, 1 g of aluminum lactate, and 0.5 g of Silica (Aerosil 200), followed by reaction in a hot air oven at 180 ° C. for 30 minutes. Subsequently, a surface treated superabsorbent polymer having a particle diameter of 150 μm or more and 850 μm or less was prepared using a sieve.

Example  6

100 g of the base polymer obtained in Preparation Example 4 was mixed with a surface crosslinking solution consisting of 1 g of ethylene carbonate, 4 g of water, and 1 g of aluminum sulfate, and then reacted in a hot air oven at 180 ° C. for 30 minutes. After the reaction of the base polymer was mixed with 0.5 g of Silica (Aerosil 200), a surface treated superabsorbent polymer having a particle diameter of 150 μm or more and 850 μm or less was prepared using a sieve.

Example  7

100 g of the base polymer obtained in Preparation Example 4 was mixed with a surface crosslinking solution consisting of 1 g of ethylene carbonate, 4 g of water, and 0.5 g of Silica (Aerosil 200), followed by reaction in a hot air oven at 180 ° C. for 30 minutes. Subsequently, a surface treated superabsorbent polymer having a particle diameter of 150 μm or more and 850 μm or less was prepared using a sieve.

Experimental Example

CRC, AUP, GBP of the base polymer prepared in Preparation Examples 1 to 4 and the superabsorbent polymers of Comparative Examples and Examples were measured and shown in Table 1 below, according to Equation 1 of the superabsorbent polymers of Comparative Examples and Examples. Gel strength indicators are shown in Table 1 below. At this time, the CRC and AUP are EDANA WSP 241.2. R3, EDANA WSP 242.2. It measured by R3 specification.

The gel layer fluidity may be measured by a free swell gel bed permeability test, and hereinafter, referring to FIGS. 1 to 3, the gel layer fluidity is more specifically described. Let's explain.

Measurement can be made using the apparatus of FIG. 1. More specifically, FIG. 2 is an enlarged cross-sectional view of the piston 200 in the apparatus for measuring permeability of FIG. 1, and FIG. 3 is a plan view of a portion projected on the bottom of the piston 200 in FIGS. 1 and 2.

As shown in FIG. 1, the piston 200 is positioned in the vessel 300, and the plurality of perforations 10 are formed in the piston lower portion 100 as shown in FIGS. 2 and 3.

Referring back to FIG. 1, the tank 500 and the vessel 300 are connected to each other, and the amount of the liquid introduced into the vessel 300 by the coke 600 can be adjusted, and the lower portion of the vessel 300 is provided. The mesh network 400 is formed, the lower portion of the mesh network 400 is spaced at a predetermined interval, the collection container 700 is located on the scale 800, the inflow through the mesh network 400 from the container 300 The flow rate may be measured using the scale 800 of the weight of the liquid.

Meanwhile, 2.0 g of the superabsorbent polymer prepared in Preparation Example, Comparative Example, and Example is extracted to prepare a sample, and the sample is uniformly spread on the bottom of the cylindrical cell 50. After placing the sampled cylindrical cell 50 on the mesh network 400 of the vessel 300, using the piston 200 to measure the gal height (H1) of the sample before swelling.

Subsequently, the piston 200 is removed, and the sample-folded cylindrical cell 50 is placed on the mesh network 400 of the container 300 and swollen for 60 minutes while pouring 0.9% saline. After 60 minutes, the piston 200 is placed in the container 300, the piston height H2 after swelling is measured, and the height H1 of the piston 200 before swelling and the height H2 of the piston 200 after swelling. The swelled gel layer height (H = H2-H1) is measured by measuring the difference of).

Next, as shown in FIG. 1, the piston 200 is positioned above the cylindrical cell 50, and the cork 600 of the tank 500 containing 0.9% physiological saline is opened to maintain a constant water height of 7.95 cm. do. While applying pressure to the piston 200 corresponding to a 0.3 psi weight, the amount of liquid passing through the gel layer through the computer and the balance 800 is measured at 1 second intervals for 1 minute as a function of time. The velocity Q of the liquid passing through the swollen sample can be found in units of g / s by the linear least-squares method of weight (g) versus time (seconds).

Permeability (cm 2) is obtained by the following equation:

Κ = [Q × Η × μ] / [Α × ρ × Ρ]

Where Κ = fluidity (cm 2), Q = flow rate (g / sec), Η = height of the swollen sample (cm), μ = liquid viscosity (P) (approximately 1 cP for the test solution used in this test) , A = cross-sectional area for the liquid flow (28.27 cm 2 for the sample vessel used for this test), ρ = liquid density (g / cm 3) (approximately 1 g / cm 3 for the test solution used for this test), Ρ = hydrostatic pressure (dynes / cm 2) (typically approximately 7,797 dynes / cm 2). The hydrostatic pressure is calculated from P = ρ × g × h, where ρ = liquid density (g / cm 3), g = gravity acceleration, typically 981 cm / sec 2, h = fluid height, 7.95 cm.

CRC (g / g) 0.7psi AUP (g / g) GBP (x 10 ^-8 cm ² ) Gel Strength Index (AUP / Basepolymer CRC) Preparation Example 1 49 - Preparation Example 2 44 Preparation Example 3 38 Preparation Example 4 34 Comparative Example 1 36 23 1.8 0.47 Comparative Example 2 34 22 4.4 0.45 Comparative Example 3 33 21 9.1 0.43 Comparative Example 4 32 21 10.8 0.48 Comparative Example 5 32 20 24.2 0.48 Comparative Example 6 32 24 5.4 0.63 Example 1 30 22 35.6 0.58 Example 2 28 21 43.7 0.55 Example 3 28 23 66.3 0.68 Example 4 27 23 71.9 0.68 Example 5 26 23 70.1 0.68 Example 6 26 24 67.3 0.71

As shown in Table 1, the superabsorbent polymers of Examples 1 to 6 prepared using the base polymers of Preparation Examples 3 and 4 satisfying the CRC value of the base polymer of the present invention have excellent gel layer liquid permeability (GBP) values. We can see that On the other hand, in Comparative Examples 1 to 5, the base polymer CRC value does not satisfy the scope of the present invention, it can be seen that the gel layer liquid permeability (GBP) value shows a very low value.

In addition, as in Comparative Example 6, even if the CRC value of the base polymer is satisfied, it can be confirmed that when the polyvalent cationic metal or the inorganic powder is not contained, the permeability is lowered and the gel layer liquid permeability (GBP) value is lowered. .

That is, as can be seen in Table 1, the superabsorbent polymer of the present invention satisfies a specific CRC range of the base polymer, has high internal strength, and has excellent ability to absorb water under the pressure of the superabsorbent polymer, On the surface of the water absorbent resin, a channel through which a liquid can flow, including an inorganic material such as a polyvalent metal salt or silica, can be formed to improve fluid flowability, thereby making it possible to improve gel layer fluidity.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and can be manufactured in various forms, and a person of ordinary skill in the art to which the present invention pertains has the technical idea of the present invention. However, it will be understood that other specific forms may be practiced without changing the essential features. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

Claims (12)

The superabsorbent polymer whose gel strength index of the following formula 1 is 0.5 or more. [Equation 1] Gel strength indicator = CRC of 0.7 psi AUP / base polymer of superabsorbent polymer In Formula 1, the 0.7 psi AUP (g / g) is a pressure absorbency value analyzed according to the EDANA WSP242.2.R3 method, and the CRC (g / g) of the base polymer is determined according to the EDANA WSP241.2.R3 method. It is the water retention value which analyzed CRC of base polymer before surface crosslinking. The method of claim 1, 0.7psi pressure absorption capacity (AUP) of the super absorbent polymer is in the range of 20g / g to 30g / g. The method of claim 1, The water absorbency (CRC) of the base polymer is in the range of 40g / g or less super absorbent resin. The method of claim 1, Superabsorbent polymer according to EDANA WSP241.2.R3 method of the super absorbent polymer (CRC) is in the range of 30g / g or less. The method of claim 1, The superabsorbent polymer is a super absorbent polymer having a gel layer permeability (GBP) of 30 x 10 ^-8 cm 2 or more, as measured by a free swell gel bed permeability test. The method of claim 1, The super absorbent polymer may include at least one or more of a polyvalent cationic metal and an inorganic powder. The method of claim 6, The polyvalent cation metal is a super absorbent polymer containing aluminum sulfate, aluminum lactate or aluminum phosphate. The method of claim 6, The inorganic powder is a super absorbent polymer containing silicon dioxide, aluminum silicate oxide, magnesium oxide, zinc oxide, zeolite, bentonite or kaolin. Polymerizing the monomer composition into a base polymer; Grinding the base polymer; Mixing a polyvalent cationic metal or inorganic powder with the ground base polymer; And Superabsorbent polymer production method comprising the step of surface crosslinking the base polymer. The method of claim 9, The mixing step and the surface cross-linking step is performed at the same time super absorbent polymer manufacturing method. The method of claim 9, The method of preparing a super absorbent polymer is carried out after the step of cross-linking the surface. The method of claim 9, The polymerizing step includes a monomer composition, an initiator and a crosslinking agent, The crosslinking agent is a superabsorbent polymer production method comprising from 0.05 parts by weight to 1 parts by weight relative to the monomer composition.

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