Title of Invention: Super absorbent polymer composition and manufacturing method thereof
technical field
[One]
Cross-Citation with Related Applications
[2]
This application claims the benefit of priority based on Korean Patent Application No. 10-2019-0120943 on September 30, 2019 and Korean Patent Application No. 10-2020-0126245 on September 28, 2020, All content disclosed in the literature is incorporated as a part of this specification.
[3]
The present invention relates to a superabsorbent polymer composition and a method for preparing the same. More particularly, it relates to a superabsorbent polymer composition capable of exhibiting a fast absorption rate without using a foaming agent and a method for preparing the same.
background
[4]
Super Absorbent Polymer (SAP) is a synthetic polymer material that can absorb water 500 to 1,000 times its own weight. Material), etc., are named differently. The superabsorbent polymer as described above began to be put to practical use as a sanitary tool, and now, in addition to sanitary products such as paper diapers for children and sanitary napkins, a soil repair agent for gardening, a water stop material for civil engineering and construction, a sheet for seedlings, and a freshness maintenance agent in the food distribution field. , and is widely used as a material for poultice.
[5]
In most cases, these superabsorbent polymers are widely used in sanitary materials such as diapers and sanitary napkins. In such a sanitary material, the superabsorbent polymer is generally included in a state spread in the pulp. However, in recent years, efforts have been made to provide sanitary materials such as diapers having a thinner thickness, and as a part of that, the content of pulp is reduced or, further, so-called pulpless diapers, etc. in which no pulp is used at all Development is actively underway.
[6]
As such, in the case of a sanitary material in which the pulp content is reduced or in which pulp is not used, the super absorbent polymer is included in a relatively high ratio, and these super absorbent polymer particles are inevitably included in multiple layers in the sanitary material. In order for the entire superabsorbent polymer particles included in the multi-layered structure to more efficiently absorb liquids such as urine, the superabsorbent polymer needs to basically exhibit high absorption performance and absorption rate.
[7]
Accordingly, in recent years, attempts have been continuously made to manufacture and provide a superabsorbent polymer having an improved absorption rate.
[8]
The most common method for increasing the absorption rate is a method of increasing the surface area of ​​the superabsorbent polymer by forming a porous structure inside the superabsorbent polymer.
[9]
As such, in order to increase the surface area of ​​the superabsorbent polymer, conventionally, a porous structure is formed in the base resin powder by cross-linking polymerization using a carbonate-based foaming agent, or bubbles are formed in the monomer composition in the presence of a surfactant and/or dispersant. A method of forming the porous structure by conducting cross-linking polymerization after introducing was applied.
[10]
However, it is difficult to achieve an absorption rate above a certain level by any previously known method, so the development of a technology capable of further improving the absorption rate has been continuously requested.
[11]
Moreover, in order to obtain a superabsorbent polymer with a further improved absorption rate by the conventional method, it is inevitably accompanied by the use of an excessive amount of a foaming agent and/or surfactant. Disadvantages that surface tension, liquid permeability or bulk density are lowered have appeared. In particular, when a foaming agent and a surfactant are applied during polymerization, pores are created in the superabsorbent polymer, which weakens the strength of the superabsorbent polymer and causes a lot of fine powder in the grinding process after drying, which may result in poor productivity.
[12]
Accordingly, the development of a technology capable of further improving the absorption rate of the superabsorbent polymer while reducing the use of surfactants and/or foaming agents has been continuously requested.
DETAILED DESCRIPTION OF THE INVENTION
technical challenge
[13]
In order to solve the problems of the prior art, it is an object of the present invention to provide a super absorbent polymer composition capable of exhibiting a fast absorption rate without using a foaming agent and a method for preparing the same.
means of solving the problem
[14]
In order to achieve the above object, according to one aspect of the present invention,
[15]
A base resin comprising a crosslinked polymer of an acrylic acid monomer and an internal crosslinking agent at least partially neutralized with an acidic group, and a surface crosslinking layer formed on the surface of the base resin and further crosslinking the crosslinked polymer via a surface crosslinking agent A superabsorbent polymer comprising a; and
[16]
a residual surface crosslinking agent that does not form the surface crosslinking layer;
[17]
The residual surface crosslinking agent that does not form the surface crosslinking layer includes a carbonate-based compound and a diol-based compound, the residual carbonate-based compound is 100 ppm or more based on the total weight of the superabsorbent polymer composition, and the residual diol-based compound is the 1,000 ppm or more based on the total weight of the superabsorbent polymer composition,
[18]
Provided is a super absorbent polymer composition satisfying the following 1) to 3):
[19]
1) Absorption rate (vortex time) by the vortex method is 65 seconds or less;
[20]
2) The content of water-soluble components after swelling for 16 hours measured according to the method of WSP 270.3 of the EDANA method is 15% by weight or less based on the total weight of the superabsorbent polymer composition; and
[21]
3) Bulk density of 0.67 g/cm 3 or more
[22]
[23]
In addition, according to another aspect of the present invention,
[24]
preparing a base resin comprising an acrylic acid-based monomer having an acidic group and at least a portion of the acidic group neutralized, and a crosslinked polymer in which the acrylic acid-based monomer is crosslinked by polymerization of a monomer composition; and
[25]
performing a surface crosslinking reaction on the base resin in the presence of a surface crosslinking agent;
[26]
including,
[27]
The surface crosslinking agent comprises at least one carbonate-based compound and at least one diol-based compound,
[28]
A method for preparing a superabsorbent polymer composition is provided.
Effects of the Invention
[29]
According to the superabsorbent polymer composition of the present invention and a method for preparing the same, it is possible to provide a high-quality superabsorbent polymer that exhibits excellent absorbent properties and achieves a fast absorption rate without using a foaming agent.
Modes for carrying out the invention
[30]
Since the present invention may have various changes and may have various forms, specific embodiments will be illustrated and described in detail below. However, this is not intended to limit the present invention to the specific disclosed form, it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.
[31]
Hereinafter, a superabsorbent polymer composition and a manufacturing method thereof according to an embodiment of the present invention will be described in detail.
[32]
[33]
The superabsorbent polymer composition according to an embodiment of the present invention,
[34]
A base resin comprising a crosslinked polymer of an acrylic acid monomer and an internal crosslinking agent at least partially neutralized with an acidic group, and a surface crosslinking layer formed on the surface of the base resin and further crosslinking the crosslinked polymer via a surface crosslinking agent A superabsorbent polymer comprising a; and
[35]
a residual surface crosslinking agent that does not form the surface crosslinking layer;
[36]
The residual surface crosslinking agent that does not form the surface crosslinking layer includes a carbonate-based compound and a diol-based compound, the residual carbonate-based compound is 100 ppm or more based on the total weight of the superabsorbent polymer composition, and the residual diol-based compound is the 1,000 ppm or more based on the total weight of the superabsorbent polymer composition,
[37]
It is characterized in that the following 1) to 3) are satisfied:
[38]
1) Absorption rate (vortex time) by the vortex method is 65 seconds or less;
[39]
2) The content of water-soluble components after swelling for 16 hours measured according to the method of WSP 270.3 of the EDANA method is 15% by weight or less based on the total weight of the superabsorbent polymer composition; and
[40]
3) Bulk density of 0.67 g/cm 3 or more
[41]
In addition, the method for preparing the superabsorbent polymer composition according to another embodiment of the present invention comprises:
[42]
preparing a base resin comprising an acrylic acid-based monomer having an acidic group and at least a portion of the acidic group neutralized, and a crosslinked polymer in which the acrylic acid-based monomer is crosslinked by polymerization of a monomer composition; and
[43]
performing a surface crosslinking reaction on the base resin in the presence of a surface crosslinking agent;
[44]
including,
[45]
The surface crosslinking agent is characterized in that it includes at least one carbonate-based compound and at least one diol-based compound.
[46]
[47]
For reference, in the present specification, "polymer" or "polymer" means a polymerized state of an acrylic acid-based monomer, and may cover all moisture content ranges, all particle size ranges, and all surface cross-linked or processed states. Among the polymers, a polymer having a water content (moisture content) of about 40% by weight or more in a state before drying after polymerization may be referred to as a hydrogel polymer. Also, among the above polymers, a polymer having a particle diameter of 150 μm or less may be referred to as “fine powder”.
[48]
In addition, "super absorbent polymer" means the polymer itself depending on the context, or the polymer is subjected to additional processes such as surface crosslinking, fine powder reassembly, drying, pulverization, classification, etc. to make it suitable for commercialization. It is used to cover all of them.
[49]
In the specification of the present invention, "base resin" or "base resin powder" is made in the form of particles or powder by drying and pulverizing a polymer in which an acrylic acid-based monomer is polymerized, which will be described later by surface modification or surface crosslinking. It refers to a polymer in a state in which the step has not been performed.
[50]
[51]
The hydrogel polymer obtained by polymerization of an acrylic acid monomer is marketed as a powdery product, a super absorbent polymer, through processes such as drying, pulverization, classification, and surface crosslinking. In recent years, attempts have been made to provide a superabsorbent polymer having an improved absorption rate.
[52]
The most common method for increasing the absorption rate is a method of increasing the surface area of ​​the superabsorbent polymer by forming a porous structure inside the superabsorbent polymer. A method of forming a porous structure in the base resin powder as the cross-linking polymerization proceeds is generally adopted.
[53]
However, according to the use of the foaming agent, various physical properties of the superabsorbent polymer, for example, surface tension, liquid permeability or bulk density, etc. are lowered, and the amount of fine powder generated is increased. The development of a technology that can improve the absorption rate of
[54]
Accordingly, the inventors of the present invention have arrived at the present invention by confirming that it is possible to provide a superabsorbent polymer having improved overall absorption properties and absorption rate by controlling the conditions of the surface crosslinking process without using a foaming agent.
[55]
More specifically, according to one embodiment of the present invention, a surface crosslinking layer is formed on the base resin prepared without a foaming process, a specific surface crosslinking agent is combined during the surface crosslinking reaction for the base resin, and the content is higher than a certain amount. It was confirmed that a superabsorbent polymer having an improved absorption rate without a porous structure could be prepared by performing the surface crosslinking reaction under milder conditions than in the prior art.
[56]
Therefore, according to one embodiment of the present invention, it is possible to provide a superabsorbent polymer in which all of the absorbent properties, surface tension, liquid permeability, bulk density, and absorption rate are maintained excellently.
[57]
In the method for preparing the superabsorbent polymer composition according to the exemplary embodiment of the present invention, first, an acrylic acid-based monomer having an acidic group and at least a portion of the acidic group neutralized, and the monomer composition are polymerized to cross-polymerize the acrylic acid-based monomer. A base resin containing a crosslinked polymer is prepared.
[58]
This will be described in more detail below.
[59]
The monomer composition, which is a raw material for the superabsorbent polymer, includes an acrylic acid-based monomer having an acid group and at least a portion of the acid group neutralized, and a polymerization initiator.
[60]
The acrylic acid-based monomer is a compound represented by the following formula (1):
[61]
[Formula 1]
[62]
R 1 -COOM 1
[63]
In Formula 1,
[64]
R 1 is an alkyl group having 2 to 5 carbon atoms including an unsaturated bond,
[65]
M 1 is a hydrogen atom, a monovalent or divalent metal, an ammonium group, or an organic amine salt.
[66]
Preferably, the acrylic acid-based monomer includes at least one selected from the group consisting of acrylic acid, methacrylic acid, and monovalent metal salts, divalent metal salts, ammonium salts and organic amine salts thereof.
[67]
Here, the acrylic acid-based monomer may have an acidic group and at least a portion of the acidic group is neutralized. Preferably, the monomer may be partially neutralized with an alkali material such as sodium hydroxide, potassium hydroxide, calcium hydroxide, ammonium hydroxide, and the like. In this case, the degree of neutralization of the acrylic acid-based monomer may be 40 to 95 mol%, or 40 to 80 mol%, or 45 to 75 mol%. The range of the degree of neutralization may be adjusted according to the final physical properties. However, if the degree of neutralization is too high, the neutralized monomer may be precipitated and polymerization may be difficult to proceed smoothly. there is.
[68]
The concentration of the acrylic acid-based monomer may be about 20 to about 60% by weight, preferably about 40 to about 50% by weight, based on the monomer composition including the raw material and solvent of the superabsorbent polymer, and the polymerization time and It may be an appropriate concentration in consideration of the reaction conditions and the like. However, if the concentration of the monomer is too low, the yield of the superabsorbent polymer may be low and economical problems may occur. Conversely, if the concentration is too high, some of the monomer is precipitated or the grinding efficiency is low when the polymerized hydrogel polymer is pulverized. Process problems may occur, and the physical properties of the superabsorbent polymer may be deteriorated.
[69]
The polymerization initiator used during polymerization in the method for preparing the superabsorbent polymer of the present invention is not particularly limited as long as it is generally used in the manufacture of the superabsorbent polymer.
[70]
Specifically, as the polymerization initiator, a thermal polymerization initiator or a photopolymerization initiator according to UV irradiation may be used according to a polymerization method. However, even by the photopolymerization method, a certain amount of heat is generated by irradiation such as ultraviolet irradiation, and a certain amount of heat is generated according to the progress of the polymerization reaction, which is an exothermic reaction, so a thermal polymerization initiator may be additionally included.
[71]
The photopolymerization initiator may be used without limitation in its composition as long as it is a compound capable of forming radicals by light such as ultraviolet rays.
[72]
As the photopolymerization initiator, for example, benzoin ether, dialkyl acetophenone, hydroxyl alkylketone, phenyl glyoxylate, benzyl dimethyl ketal Ketal), acyl phosphine (acyl phosphine), and alpha-aminoketone (α-aminoketone) may be used at least one selected from the group consisting of. On the other hand, as a specific example of acylphosphine, commercially available lucirin TPO, that is, 2,4,6-trimethyl-benzoyl-trimethyl phosphine oxide (2,4,6-trimethyl-benzoyl-trimethyl phosphine oxide) may be used. . A more diverse photoinitiator is well specified in Reinhold Schwalm's book 'UV Coatings: Basics, Recent Developments and New Application' (Elsevier 2007) p115, but is not limited to the above-described example.
[73]
The photopolymerization initiator may be included in a concentration of about 0.01 to about 1.0 wt% based on the monomer composition. If the concentration of the photopolymerization initiator is too low, the polymerization rate may be slowed, and if the concentration of the photopolymerization initiator is too high, the molecular weight of the superabsorbent polymer may be small and physical properties may be non-uniform.
[74]
In addition, as the thermal polymerization initiator, at least one selected from the group consisting of a persulfate-based initiator, an azo-based initiator, hydrogen peroxide, and ascorbic acid may 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 (Ammonium persulfate; (NH 4 ) 2 S 2 O 8) and the like, and examples of the azo-based initiator include 2,2-azobis-(2-amidinopropane)dihydrochloride (2,2-azobis(2-amidinopropane) dihydrochloride), 2,2-azobis -(N,N-dimethylene)isobutyramidine dihydrochloride (2,2-azobis-(N,N-dimethylene)isobutyramidine dihydrochloride), 2-(carbamoylazo)isobutyronitrile (2-(carbamoylazo) )isobutylonitril), 2,2-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride (2,2-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride ), 4,4-azobis-(4-cyanovaleric acid) (4,4-azobis-(4-cyanovaleric acid)) and the like. More various thermal polymerization initiators are well described in Odian's book 'Principle of Polymerization (Wiley, 1981)', p203, and are not limited to the above-described examples.
[75]
According to an embodiment of the present invention, the monomer composition includes an internal crosslinking agent as a raw material for the super absorbent polymer. The internal crosslinking agent includes a crosslinking agent having at least one functional group capable of reacting with the acrylic acid-based monomer and at least one ethylenically unsaturated group; Alternatively, a crosslinking agent having at least two functional groups capable of reacting with a substituent of the acrylic acid-based monomer and/or a substituent formed by hydrolysis of the monomer may be used.
[76]
The internal crosslinking agent is for crosslinking the inside of the polymer in which the acrylic acid-based monomer is polymerized, and is distinguished from the surface crosslinking agent for crosslinking the surface of the polymer.
[77]
Specific examples of the internal crosslinking agent include N,N'-methylenebisacrylamide, trimethylolpropane tri(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol (meth)acrylate, propylene glycol di(meth) ) acrylate, polypropylene glycol (meth) acrylate, butanediol di (meth) acrylate, butylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, hexanediol di (meth) acrylate Acrylate, triethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, dipentaerythritol pentaacrylate, glycerin tri(meth)acrylate, pentaery At least one selected from the group consisting of stall tetraacrylate, triarylamine, ethylene glycol diglycidyl ether, propylene glycol, glycerin, and polyethylene glycol diglycidyl ether, ethylene carbonate may be used. The internal crosslinking agent may be included in a concentration of about 0.01 to about 0.5% by weight based on the monomer composition to crosslink the polymerized polymer.
[78]
According to one embodiment of the present invention, the monomer composition does not include a blowing agent.
[79]
The foaming agent is used to improve the absorption rate by increasing the surface area by forming pores in the hydrogel polymer due to foaming during polymerization. As the foaming agent, a carbonate-based foaming agent is mainly used, for example, sodium bicarbonate, sodium carbonate, potassium bicarbonate, potassium carbonate, calcium bicarbonate. ), calcium bicarbonate, magnesium bicarbonate, or magnesium carbonate.
[80]
However, as described above, there is a problem in that other physical properties of the superabsorbent polymer, for example, surface tension, liquid permeability, bulk density, etc., decrease, and the amount of fine powder is increased according to the use of the foaming agent. Accordingly, in one embodiment of the present invention, in order to solve the above problems, a foaming agent is not used, and thus an excellent absorption rate can be achieved while maintaining a high bulk density and reducing the amount of fine powder generated.
[81]
In the manufacturing method of the present invention, the monomer composition of the super absorbent polymer may further include additives such as a thickener, a plasticizer, a storage stabilizer, and an antioxidant, if necessary.
[82]
Raw materials such as an acrylic acid-based monomer having an acidic group and at least a portion of the acidic group neutralized, a photopolymerization initiator, a thermal polymerization initiator, an internal crosslinking agent, and an additive may be prepared in the form of a monomer composition solution dissolved in a solvent.
[83]
The solvent that can be used at this time can be used without limitation in its composition as long as it can dissolve the above-mentioned components, for example, water, ethanol, ethylene glycol, diethylene glycol, triethylene glycol, 1,4-butanediol, Propylene glycol, ethylene glycol monobutyl ether, 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, butyrolactone, carbitol, methyl cellosolve acetate and N,N-dimethylacetamide may be used in combination.
[84]
The solvent may be included in the remaining amount excluding the above-mentioned components with respect to the total content of the monomer composition.
[85]
On the other hand, as long as the method for forming the hydrogel polymer by thermal polymerization or photopolymerization of such a monomer composition is also a commonly used polymerization method, there is no particular limitation on the configuration.
[86]
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 be carried out in a reactor having a stirring shaft such as a kneader. The process may be carried out in a reactor equipped with a conveyor belt or in a flat-bottomed vessel, but the polymerization method described above is an example, and the present invention is not limited to the polymerization method described above.
[87]
For example, as described above, the hydrogel polymer obtained by thermal polymerization by supplying hot air or heating the reactor to a reactor such as a kneader having a stirring shaft is fed to the reactor outlet according to the shape of the stirring shaft provided in the reactor. The discharged hydrogel polymer may be in the form of several centimeters to several millimeters. Specifically, the size of the hydrogel polymer obtained may vary depending on the concentration and injection rate of the monomer composition to be injected, and a hydrogel polymer having a weight average particle diameter of 2 to 50 mm can be obtained.
[88]
In addition, as described above, when photopolymerization is carried out in a reactor equipped with a movable conveyor belt or in a flat-bottomed container, the generally obtained hydrogel polymer may be a sheet-like hydrogel polymer having the width of the belt. At this time, the thickness of the polymer sheet varies depending on the concentration of the injected monomer composition and the injection rate or injection amount, but it is preferable to supply the monomer composition so that a polymer sheet having a thickness of usually about 0.5 to about 5 cm can be obtained. . When the monomer composition is supplied so that the thickness of the polymer on the sheet is too thin, the production efficiency is low, which is not preferable. When the thickness of the polymer on the sheet exceeds 5 cm, the polymerization reaction occurs evenly over the entire thickness due to the excessive thickness it may not be
[89]
In this case, the typical water content of the hydrogel polymer obtained by this method may be about 40 to about 80 wt%. Meanwhile, in the present specification, "moisture content" refers to the amount of moisture occupied with respect to the total weight of the hydrogel polymer, and refers to a value obtained by subtracting the weight of the polymer in a dry state from the weight of the hydrogel polymer. Specifically, it is defined as a value calculated by measuring the weight loss due to evaporation of moisture in the polymer during drying by raising the temperature of the polymer through infrared heating.
[90]
At this time, the drying condition is set to 20 minutes including 5 minutes of the temperature rise step in a manner such that the temperature is raised from room temperature to about 180° C. and then maintained at 180° C., and the moisture content is measured.
[91]
Next, a step of drying the obtained hydrogel polymer is performed.
[92]
In this case, if necessary, a step of coarsely pulverizing before drying may be further performed in order to increase the efficiency of the drying step.
[93]
At this time, the grinder used is not limited in configuration, but specifically, a vertical pulverizer, a turbo cutter, a turbo grinder, a rotary cutter mill, cutting Including any one selected from the group of crushing devices consisting of a cutter mill, a disc mill, a shred crusher, a crusher, a chopper, and a disc cutter However, it is not limited to the above-described example.
[94]
In this case, in the grinding step, the hydrogel polymer may have a particle diameter of about 2 to about 10 mm.
[95]
Grinding to a particle size of less than 2 mm is not technically easy due to the high water content of the hydrogel polymer, and a phenomenon of agglomeration between the pulverized particles may occur. On the other hand, when pulverizing to a particle size of more than 10 mm, the effect of increasing the efficiency of the subsequent drying step is insignificant.
[96]
Drying is performed on the hydrogel polymer immediately after polymerization that has been pulverized as described above or has not undergone a pulverization step. In this case, the drying temperature of the drying step may be about 150 to about 250 ℃. When the drying temperature is less than 150°C, the drying time becomes excessively long and there is a risk that the physical properties of the superabsorbent polymer finally formed may decrease. fine powder may occur, and there is a fear that the physical properties of the superabsorbent polymer finally formed may be deteriorated. Therefore, preferably, the drying may be carried out at a temperature of about 150 to about 200 °C, more preferably at a temperature of about 160 to about 180 °C.
[97]
Meanwhile, in the case of drying time, in consideration of process efficiency, etc., the drying time may be performed for about 20 to about 90 minutes, but is not limited thereto.
[98]
As long as the drying method of the drying step is also commonly used as a drying process for the hydrogel polymer, it may be selected and used without limitation in its configuration. Specifically, the drying step may be performed by a method such as hot air supply, infrared irradiation, microwave irradiation, or ultraviolet irradiation. After the drying step, the moisture content of the polymer may be about 0.1 to about 10% by weight.
[99]
Next, a step of pulverizing the dried polymer obtained through such a drying step is performed.
[100]
The polymer powder obtained after the grinding step may have a particle diameter of about 150 to about 850 μm. The grinder used for grinding to such a particle size is specifically, a pin mill, a hammer mill, a screw mill, a roll mill, a disc mill, or a jog. A mill (jog mill) or the like may be used, but the present invention is not limited to the above-described examples.
[101]
And, in order to manage the physical properties of the superabsorbent polymer powder to be finalized after the pulverization step, a separate process of classifying the polymer powder obtained after pulverization according to the particle size may be performed, and the polymer powder is mixed in a certain weight ratio according to the particle size range. It can be classified as
[102]
What is made in the form of particles or powder by drying and pulverizing a polymer obtained by polymerization of an acrylic acid-based monomer through the process as described above is referred to as a base resin.
[103]
The base resin of the present invention prepared as described above has a water retention capacity (CRC) of about 32 g/g or more, or about 33 g/g or more, or about 34 g/g or more, measured according to EDANA method WSP 241.3, about 50 g/g or less, or about 49 g/g or less, or about 48 g/g or less.
[104]
Although the water holding capacity (CRC) of the base resin inevitably decreases in the surface crosslinking reaction step to be described later, according to the present invention, the difference in water holding capacity before and after the surface crosslinking reaction is not large. The water holding capacity of the final product can still be maintained high.
[105]
Next, in the presence of a surface crosslinking agent, a surface crosslinking reaction is performed on the base resin to form a surface crosslinking layer in which the crosslinked polymer is further crosslinked via a surface crosslinking agent on the surface of the base resin.
[106]
In a general method for producing a superabsorbent polymer, a surface crosslinking reaction is performed on the pulverized polymer by mixing a surface crosslinking solution containing a surface crosslinking agent with a dried and pulverized polymer, that is, a base resin, and then heating the mixture to increase the temperature. carry out
[107]
The surface crosslinking step is a step of inducing a crosslinking reaction on the surface of the pulverized polymer in the presence of a surface crosslinking agent, thereby forming a superabsorbent polymer having more improved physical properties, particularly an improved absorption rate. Through this surface crosslinking, a surface crosslinking layer is formed on the surface of the pulverized polymer particles.
[108]
In general, since the surface crosslinking agent is applied to the surface of the superabsorbent polymer particles, the surface crosslinking reaction occurs on the surface of the superabsorbent polymer particles, which improves crosslinking properties on the surface of the particles without substantially affecting the inside of the particles. Therefore, the surface cross-linked super absorbent polymer particles have a higher degree of cross-linking near the surface than inside.
[109]
The superabsorbent polymer with the surface cross-linking layer has a higher absorption rate than the base resin before the surface cross-linking layer is formed, but has a reduced absorption capacity such as water holding capacity (CRC). Therefore, the physical properties of the final product vary depending on the water retention capacity of the base resin, the thickness of the surface cross-linking layer, and the cross-linking density. there is
[110]
According to one embodiment of the present invention, in the surface crosslinking reaction step, one or more carbonate-based compounds and one or more diol-based compounds may be used in combination as a surface crosslinking agent to improve the absorption rate without significantly lowering water retention capacity.
[111]
More specifically, according to one embodiment of the present invention, the at least one carbonate-based compound may be selected from the group consisting of ethylene carbonate, propylene carbonate, butylene carbonate, and glycerol carbonate, and the at least one diol-based compound may be selected from the group consisting of ethylene glycol, 1,3-propanediol, 1,4-butanediol, propylene glycol, and glycerol.
[112]
For example, as the surface crosslinking agent of the present invention, four types of ethylene carbonate, propylene carbonate, glycerol carbonate, and propylene glycol may be used.
[113]
As another example, as the surface crosslinking agent of the present invention, three types of ethylene carbonate, propylene carbonate, and propylene glycol may be used.
[114]
In addition, the carbonate-based compound may be used in an amount of 0.4 parts by weight or more, or 0.6 parts by weight or more, and 2.5 parts by weight or less, or 2.0 parts by weight or less, based on 100 parts by weight of the base resin.
[115]
In addition, the diol-based compound may be used in an amount of 0.2 parts by weight or more, or 0.25 parts by weight or more, and 3.0 parts by weight or less, or 2.0 parts by weight or less, based on 100 parts by weight of the base resin.
[116]
When the content of the carbonate-based surface cross-linking agent and the diol-based surface cross-linking agent satisfies the above-described ranges, overall absorption properties and absorption rate may be improved at the same time.
[117]
As the surface crosslinking step is performed using the surface crosslinking agent in the above content, the residual surface crosslinking agent that does not form the surface crosslinking layer after the surface crosslinking reaction is completed is included in the superabsorbent polymer composition.
[118]
The residual surface crosslinking agent that does not form the surface crosslinking layer may include an unreacted surface crosslinking agent remaining without reacting with the crosslinked polymer and a decomposition product of the surface crosslinking agent after the surface crosslinking reaction.
[119]
Among these residual surface crosslinking agents, the carbonate-based compound is 100 ppm or more based on the total weight of the superabsorbent polymer composition, for example, 400 ppm or more, or 500 ppm or more, and 2,000 ppm or less, or 1,800 ppm or less, or 1000 ppm or less, or It may be 900 ppm or less.
[120]
In addition, the residual diol-based compound is 1,000 ppm or more based on the total weight of the superabsorbent polymer composition, for example, 1,000 ppm or more, or 1,100 ppm or more, and 10,000 ppm or less, or 9,000 ppm or less, or 2,000 ppm or less, or It may be 1,800 ppm or less.
[121]
As the superabsorbent polymer composition of the present invention includes the residual carbonate-based compound and the diol-based compound in the above content, an improved absorption rate can be achieved without deterioration of other physical properties.
[122]
Meanwhile, when the surface crosslinking agent is added, water may be additionally mixed together and added in the form of a surface crosslinking solution. When water is added, there is an advantage that the surface crosslinking agent can be uniformly dispersed in the polymer. At this time, the content of the added water is about 1 to about 1 to about 100 parts by weight of the base resin for the purpose of inducing even dispersion of the surface crosslinking agent and preventing agglomeration of the polymer powder and at the same time optimizing the surface penetration depth of the surface crosslinking agent. It is preferably added in a proportion of 10 parts by weight.
[123]
On the other hand, in the above-mentioned surface crosslinking step, in addition to the surface crosslinking agent, a polyvalent metal salt, for example, an aluminum salt, more specifically, aluminum sulfate, potassium salt, ammonium salt, sodium salt, and hydrochloride salt using at least one selected from the group consisting of can proceed.
[124]
By applying heat to the mixture of the base resin and the surface crosslinking agent to increase the temperature, a surface crosslinking layer in which the crosslinked polymer is further crosslinked through the surface crosslinking agent is formed on the surface of the base resin.
[125]
On the other hand, according to one embodiment of the present invention, the surface crosslinking reaction step may be performed at a lower temperature than conventional temperature conditions. For example, the surface crosslinking reaction may be performed at a temperature of 60 to 190°C, or 60 to 188°C, or 60 to 186°C for 20 minutes to 100 minutes.
[126]
A typical surface crosslinking reaction is carried out at a temperature exceeding 190° C., and due to the surface crosslinking reaction at such a high temperature, the color of the product changes to yellow and a bad odor becomes severe when the superabsorbent polymer is swollen.
[127]
However, according to one embodiment of the present invention, this problem can be prevented by performing the surface crosslinking reaction at a lower temperature than before.
[128]
The means for increasing the temperature for the surface modification reaction is not particularly limited. It can be heated by supplying a heating medium or by directly supplying a heat source. At this time, as the type of heating medium that can be used, a fluid having an elevated temperature such as steam, hot air, or hot oil may be used, but the present invention is not limited thereto. It can be appropriately selected in consideration of the target temperature. On the other hand, the directly supplied heat source may be a heating method through electricity or a gas heating method, but the present invention is not limited to the above-described example.
[129]
Therefore, according to one embodiment of the present invention, a fast absorption rate is achieved without reducing physical properties such as water retention capacity and absorbency under pressure due to mixing action such as non-use of a foaming agent, characteristics of the base resin, and optimization of the surface crosslinking step. In addition, it is possible to provide a superabsorbent polymer composition having excellent physical properties such as surface tension, liquid permeability, and bulk density.
[130]
Accordingly, the superabsorbent polymer composition according to an embodiment of the present invention is formed on a surface of a base resin comprising a crosslinked polymer of an acrylic acid-based monomer and an internal crosslinking agent, at least a part of which has a neutralized acidic group, and the base resin, a superabsorbent polymer including a surface crosslinking layer in which the crosslinked polymer is further crosslinked through a surface crosslinking agent; and a residual surface crosslinking agent that does not form the surface crosslinking layer, the residual surface crosslinking agent not forming the surface crosslinking layer includes a carbonate-based compound and a diol-based compound, and the residual carbonate-based compound is the superabsorbent polymer composition 100 ppm or more based on the total weight of , the residual diol-based compound is 1,000 ppm or more based on the total weight of the superabsorbent polymer composition, and the following 1) to 3) are satisfied.
[131]
1) Absorption rate (vortex time) by the vortex method is 65 seconds or less;
[132]
2) The content of water-soluble components after swelling for 16 hours measured according to the method of WSP 270.3 of the EDANA method is 15% by weight or less based on the total weight of the superabsorbent polymer composition; and
[133]
3) Bulk density of 0.67 g/cm 3 or more
[134]
In addition, the surface crosslinking agent may include one or more carbonate-based compounds and one or more diol-based compounds.
[135]
The at least one carbonate-based compound may be selected from the group consisting of ethylene carbonate, propylene carbonate, butylene carbonate, and glycerol carbonate, and the at least one diol-based compound is ethylene glycol, propylene glycol, 1,3-propanediol , may be selected from the group consisting of 1,4-butanediol and glycerol.
[136]
For example, as the surface crosslinking agent of the present invention, four types of ethylene carbonate, propylene carbonate, glycerol carbonate, and propylene glycol may be used.
[137]
As another example, as the surface crosslinking agent of the present invention, three types of ethylene carbonate, propylene carbonate, and propylene glycol may be used.
[138]
Among these residual surface crosslinking agents, the carbonate-based compound is 100 ppm or more based on the total weight of the superabsorbent polymer composition, for example, 400 ppm or more, or 500 ppm or more, and 2,000 ppm or less, or 1,800) ppm or less, or 1000 ppm or less, or 900 ppm or less.
[139]
In addition, the diol-based compound is present in an amount of 1,000 ppm or more, for example, 1,000 ppm or more, or 1,100 ppm or more, and 10,000 ppm or less, or 9,000 ppm or less, or 2,000 ppm or less, or 1,800 ppm based on the total weight of the superabsorbent polymer composition. ppm or less.
[140]
As the superabsorbent polymer composition of the present invention includes the residual carbonate-based compound and the diol-based compound in the above content, an improved absorption rate can be achieved without deterioration of other physical properties.
[141]
In addition, the superabsorbent polymer composition has a low water-soluble component (EC) by controlling the water holding capacity (CRC) of the base resin to be low. More specifically, in the superabsorbent polymer composition, the content of water-soluble components after swelling for 16 hours measured according to the method of WSP 270.3 of the EDANA method is 15% by weight or less based on the total weight of the superabsorbent polymer composition, for example, 14.5% by weight. or less, or 13 wt% or less, or 12.5 wt% or less, or 11 wt% or less. The lower the value of the water-soluble component (EC) is, the better, so the lower limit of the water-soluble component (EC) is 0 wt% in theory, but for example 1 wt% or more, or 2 wt% or more, or 3 wt% or more there is.
[142]
In addition, the superabsorbent polymer composition has a high bulk density due to non-foaming of the monomer composition. More specifically, the super absorbent polymer composition has a bulk density measured according to WSP 250.3 of 0.67 g/cm 3 or more, or 0.68 g/cm 3 or more, and 0.80 g/cm 3 or less, or 0.75 g /cm 3 or more. cm 3 or less, or 0.70 g/cm 3 or less.
[143]
In addition, the superabsorbent polymer composition of the present invention may have a vortex time of 65 seconds or less, or about 60 seconds or less, or about 58 seconds or less, or 55 seconds or less, or 52 seconds or less by a vortex method. The lower the value of the absorption rate is, the better it is. The lower limit of the absorption rate is 0 seconds in theory, but for example, it may be about 5 seconds or more, or about 10 seconds or more, or about 12 seconds or more.
[144]
The absorption rate refers to the time (time, unit: seconds) during which the vortex of the liquid disappears due to rapid absorption when the superabsorbent polymer is added to physiological saline and stirred. It can be seen that has a fast initial absorption rate.
[145]
In addition, the superabsorbent polymer composition of the present invention has a water retention capacity (CRC) of about 29 g/g or more, or about 30 g/g or more, or about 31 g/g, measured according to the EDANA method WSP 241.3. or more, and may have a range of about 40 g/g or less, or about 38 g/g or less, or about 35 g/g or less.
[146]
In addition, the superabsorbent polymer composition of the present invention may satisfy the following relational expression (1).
[147]
[Relational Expression 1]
[148]
1 g/g ≤ Water retention capacity (CRC) of the base resin as measured in accordance with WSP 241.3 of the EDANA method - Water retention capacity (CRC) of the superabsorbent polymer as measured in accordance with WSP 241.3 of the EDANA method ≤ 12 g/g
[149]
According to Relation 1, the water holding capacity (CRC) of the base resin is about 1 to about 12 g/g, or about 2 to about 12 g/g, than the water holding capacity (CRC) of the superabsorbent polymer including the surface cross-linking layer; or from about 3 to about 12 g/g, or from about 3 to about 11 g/g, or from about 3 to about 10 g/g, or from about 3 to about 8 g/g, or from about 3 to about 7 g/g After preparing a base resin with a small difference in water holding capacity between the base resin and the final product, that is, the superabsorbent polymer, and then performing a surface crosslinking step under specific conditions, the water holding capacity decreases and the absorption rate increases. We can provide improved products.
[150]
In addition, the superabsorbent polymer of the present invention has an absorbency under pressure (AUP) of 0.7 psi measured according to WSP 242.3 of the EDANA method of about 21 g/g or more, or about 22 g/g or more, or about 23 g/g or more, , about 30 g/g or less, or about 29 g/g or less, or about 28 g/g or less.
[151]
The present invention will be described in more detail in the following examples. However, the following examples only illustrate the present invention, and the content of the present invention is not limited by the following examples.
[152]
[153]

[154]
Preparation of super absorbent polymer
[155]
Example 1
[156]
600 g of acrylic acid, 2.04 g of PEGDA400 (polyethylene glycol diacrylate 400) as an internal crosslinking agent, 0.048 g of photoinitiator diphenyl(2,4,6-trimethylbenzoyl)-phosphine oxide, heat in a 3L glass container equipped with a stirrer and thermometer, heat An aqueous solution of a water-soluble unsaturated monomer was prepared by mixing 1.2 g of an initiator sodium persulfate (SPS) and 974.7 g of a 24.0% sodium hydroxide solution (degree of neutralization: 70 mol%; solid content: 45 wt%).
[157]
Thereafter, when the temperature of the aqueous monomer solution reached 50° C., UV polymerization was carried out by irradiating ultraviolet rays (irradiation amount: 10 mW/cm 2 ) for 1 minute, and maintained in the polymerization reactor for 2 minutes to obtain a hydrogel polymer. After the obtained hydrogel polymer was pulverized to a size of 2 mm * 2 mm, the water content (180 degrees, 40 minutes) was measured, and as a result, it was 47%.
[158]
The resulting gel-type resin was spread to a thickness of about 30 mm on stainless wire gauze having a pore size of 600 μm and dried in a hot air oven at 180° C. for 30 minutes. The dried polymer thus obtained was pulverized using a pulverizer, and classified through a standard mesh sieve of ASTM standard to obtain a base resin having a particle size of 150 to 850 μm.
[159]
Then, based on 100 parts by weight of the prepared base resin, water 5.4 parts by weight, ethylene carbonate 0.9 parts by weight, propylene carbonate 0.9 parts by weight, propylene glycol 0.2 parts by weight, glycerol carbonate 0.6 parts by weight, Al-S (18 hydrate) 0.4 parts by weight After evenly mixing the surface treatment solution containing the part, it was supplied to one surface crosslinking reactor, and the surface crosslinking reaction of the base resin was performed at 186° C. for 60 minutes.
[160]
After the surface treatment was completed, a surface-treated superabsorbent polymer having an average particle size of 150 to 850 μm was obtained using a sieve.
[161]
[162]
Example 2
[163]
A superabsorbent polymer was prepared in the same manner as in Example 1, except that the surface crosslinking reaction time was carried out for 40 minutes in Example 1.
[164]
[165]
Example 3
[166]
A super absorbent polymer was prepared in the same manner as in Example 1, except that 2.16 g of PEGDA400 was used during polymerization in Example 1 and the surface crosslinking reaction time was carried out for 55 minutes.
[167]
[168]
Example 4
[169]
The preparation method of the base resin was the same except that 2.54 g of PEGDA400 was used during polymerization in Example 1, and based on 100 parts by weight of the prepared base resin, 5.4 parts by weight of water, 0.6 parts by weight of ethylene carbonate, 0.6 parts by weight of propylene carbonate, propylene After evenly mixing a surface treatment solution containing 0.2 parts by weight of glycol and 0.4 parts by weight of Al-S (18 hydrate), it was supplied to one surface crosslinking reactor, and the surface crosslinking reaction of the base resin was carried out at 186° C. for 50 minutes.
[170]
[171]
Example 5
[172]
A superabsorbent polymer was prepared in the same manner as in Example 1, except that the surface crosslinking reaction time was carried out for 60 minutes in Example 4.
[173]
[174]
Example 6
[175]
A super absorbent polymer was prepared in the same manner as in Example 1, except that 1.74 g of PEGDA400 was used during polymerization in Example 1.
[176]
[177]
Comparative Example 1
[178]
A base resin was prepared in the same manner as in Example 1, except that 1.92 g of PEGDA400 was used, and based on 100 parts by weight of the prepared base resin, 3.0 parts by weight of water, 3.5 parts by weight of methanol, 0.25 parts by weight of 1,3-propanediol , a surface treatment solution containing 0.15 parts by weight of oxalic acid was uniformly mixed, then supplied to one surface crosslinking reactor, and the surface crosslinking reaction of the base resin was carried out at 195° C. for 65 minutes.
[179]
[180]
Comparative Example 2
[181]
A superabsorbent polymer was prepared in the same manner as in Comparative Example 1, except that the surface crosslinking time of Comparative Example 1 was carried out at 195° C. for 65 minutes.
[182]
[183]
Comparative Example 3
[184]
A base resin was prepared in the same manner except that 1.32 g of PEGDA400 was used in Example 1, and based on 100 parts by weight of the prepared base resin, 2.7 parts by weight of water, 4.0 parts by weight of methanol, 0.15 parts by weight of ethylene carbonate, Al-S After evenly mixing the surface treatment solution containing 1.0 parts by weight of (18 hydrate), it was supplied to one surface crosslinking reactor, and the surface crosslinking reaction of the base resin was carried out at 195°C for 70 minutes.
[185]
[186]
Comparative Example 4
[187]
A superabsorbent polymer was prepared in the same manner as in Comparative Example 3, except that the surface crosslinking reaction in Comparative Example 3 was performed at 195° C. for 80 minutes.
[188]
[189]

[190]
The superabsorbent polymers prepared in Examples and Comparative Examples were evaluated for physical properties in the following manner.
[191]
Unless otherwise indicated, all of the following physical property evaluations were conducted at constant temperature and humidity (23±2° C., relative humidity 50±10%), and physiological saline or saline means 0.9 wt% sodium chloride (NaCl) aqueous solution.
[192]
[193]
(1) Centrifuge Retention Capacity (CRC)
[194]
The water holding capacity of each resin according to the no-load absorption magnification was measured according to EDANA WSP 241.3.
[195]
Specifically, the superabsorbent polymer W 0 (g) (about 0.2 g) was uniformly put in a non-woven bag and sealed, and then immersed in physiological saline (0.9 wt %) at room temperature. After 30 minutes, the bag was drained of water for 3 minutes under the conditions of 250G using a centrifuge, and the mass W 2 (g) of the bag was measured. Moreover, after performing the same operation without using resin, the mass W1 (g) at that time was measured. Using each obtained mass, CRC (g/g) was calculated according to the following equation.
[196]
[Equation 1]
[197]
CRC (g/g) = {[W 2 (g) - W 1 (g)]/W 0 (g)} - 1
[198]
[199]
(2) Absorbtion Under Pressure (AUP)
[200]
The absorbency under pressure of 0.7 psi of each resin was measured according to the EDANA method WSP 242.3.
[201]
Specifically, a stainless steel 400 mesh wire mesh was mounted on the bottom of a plastic cylinder having an inner diameter of 60 mm. Under the conditions of room temperature and humidity of 50%, the super absorbent polymer W 0 (g) (0.90 g) is uniformly sprayed on the wire mesh, and the piston that can apply a load of 0.7 psi more uniformly thereon is slightly more than 60 mm in outer diameter. It is small, there is no gap with the inner wall of the cylinder, and the vertical movement is not disturbed. At this time, the weight W 3 (g) of the device was measured.
[202]
A glass filter having a diameter of 90 mm and a thickness of 5 mm was placed on the inside of a 150 mm diameter petro dish, and physiological saline composed of 0.9 wt% sodium chloride was placed at the same level as the upper surface of the glass filter. One filter paper having a diameter of 90 mm was loaded thereon. The measuring device was placed on the filter paper, and the liquid was absorbed under load for 1 hour. After 1 hour, the measuring device was lifted and the weight W 4 (g) was measured.
[203]
Using each obtained mass, absorbency under pressure (g/g) was calculated according to the following equation.
[204]
[Equation 2]
[205]
AUP(g/g) = [W 4 (g) - W 3 (g)]/W 0 (g)
[206]
[207]
(3) Absorption rate (Vortex time)
[208]
The absorption rate (vortex time) is to add 2 g of superabsorbent polymer to 50 mL of physiological saline at 23° C. to 24° C., and stir the magnetic bar (8.5 mm in diameter, 30 mm in length) at 600 rpm to eliminate the vortex. It was calculated by measuring the time until the time in seconds.
[209]
[210]
(4) Extractable contents (EC)
[211]
Water-soluble components were measured according to the method of EDANA method WSP 270.3.
[212]
[213]
(5) bulk density
[214]
Bulk density was measured according to the method of WSP 250.3.
[215]
[216]
The physical property values ​​for the Examples and Comparative Examples are shown in Table 1 below.
[217]
[Table 1]
Base resin
(before surface crosslinking) Super absorbent resin
(after surface crosslinking)
CRC
(g/g) Vortex
(sec) CRC
(g/g) EC
(wt%) Vortex
(sec) 0.7 psi
AUP
(g/g) bulk density (sec) Residual
carbonate compounds
(ppm) Residual
diol compounds
(ppm)
Example 1 40.0 51 32.5 12.1 51 22.6 0.67 884 1648
Example 2 40.0 51 35.5 14.5 47 22.6 0.68 855 1605
Example 3 39.1 52 32.3 12.4 52 22.1 0.69 873 1742
Example 4 35.0 55 29.5 7.6 60 23.4 0.68 527 1375
Example 5 35.0 55 32.0 10.1 58 23.4 0.67 509 1361
Example 6 44.0 49 33.4 14.8 59 23.7 0.69 854 2456
Comparative Example 1 48.0 50 35.0 17.0 86 22.0 0.69 0 915
Comparative Example 2 45.0 50 32.5 16.0 89 22.0 0.70 0 970
Comparative Example 3 54.0 48 37.5 17.7 85 18.5 0.68 42 55
Comparative Example 4 54.0 48 36.6 17.2 82 23.0 0.69 36 48
[218]
Referring to Table 1, it was confirmed that all of the Examples of the present invention exhibited excellent absorption capacity, absorption rate and bulk density.
Claims
[Claim 1]
A base resin comprising a crosslinked polymer of an acrylic acid monomer and an internal crosslinking agent at least partially neutralized with an acidic group, and a surface crosslinking layer formed on the surface of the base resin and further crosslinking the crosslinked polymer via a surface crosslinking agent Super-absorbent resin comprising; and a residual surface crosslinking agent that does not form the surface crosslinking layer, the residual surface crosslinking agent not forming the surface crosslinking layer includes a carbonate-based compound and a diol-based compound, and the residual carbonate-based compound is the superabsorbent polymer composition 100ppm or more based on the total weight of the superabsorbent polymer composition, the residual diol compound is 1,000ppm or more based on the total weight of the superabsorbent polymer composition, and the following 1) to 3) are satisfied: 1) In the vortex method Absorption rate (vortex time) by 65 seconds or less; 2) The content of water-soluble components after swelling for 16 hours measured according to the method of WSP 270.3 of the EDANA method is 15% by weight or less based on the total weight of the superabsorbent polymer composition; and 3) a bulk density of 0.67 g/cm 3 or greater.
[Claim 2]
The superabsorbent polymer composition according to claim 1, wherein the surface crosslinking agent comprises at least one carbonate-based compound and at least one diol-based compound.
[Claim 3]
The method of claim 1, wherein the carbonate-based compound is selected from the group consisting of ethylene carbonate, propylene carbonate, butylene carbonate, and glycerol carbonate, and the diol-based compound is ethylene glycol, 1,3-propanediol, 1,4- A superabsorbent polymer composition selected from the group consisting of butanediol, propylene glycol, and glycerol.
[Claim 4]
The superabsorbent polymer composition of claim 3, wherein the surface crosslinking agent is ethylene carbonate, propylene carbonate, glycerol carbonate, and propylene glycol, or ethylene carbonate, propylene carbonate, and propylene glycol.
[Claim 5]
The superabsorbent polymer composition according to claim 1, which satisfies the following Relational Equation 1: [Relational Equation 1] 1 g/g ≤ the water holding capacity (CRC) of the base resin measured according to the EDANA method WSP 241.3 - according to the EDANA method WSP 241.3 Measured water retention capacity (CRC) of superabsorbent polymer ≤ 12 g/g
[Claim 6]
According to claim 1, wherein the absorption rate (vortex time) by the vortex method is 60 seconds or less, the superabsorbent polymer composition.
[Claim 7]
The superabsorbent polymer composition according to claim 1, wherein the content of water-soluble components (after swelling for 16 hours) measured according to the method of WSP 270.3 of the EDANA method is 5 to 15% by weight based on the total weight of the superabsorbent polymer composition.
[Claim 8]
preparing a base resin comprising an acrylic acid-based monomer having an acidic group and at least a portion of the acidic group neutralized, and a crosslinked polymer in which the acrylic acid-based monomer is crosslinked by polymerization of a monomer composition; and performing a surface crosslinking reaction on the base resin in the presence of a surface crosslinking agent; The method of claim 1, wherein the surface crosslinking agent comprises at least one carbonate-based compound and at least one diol-based compound.
[Claim 9]
The method of claim 8, wherein the carbonate-based compound is selected from the group consisting of ethylene carbonate, propylene carbonate, butylene carbonate and glycerol carbonate, and the diol-based compound is ethylene glycol, propylene glycol, 1,3-propanediol, 1, A method for preparing a superabsorbent polymer composition, selected from the group consisting of 4-butanediol and glycerol.
[Claim 10]
The method of claim 9, wherein the surface crosslinking agent is ethylene carbonate, propylene carbonate, glycerol carbonate, and propylene glycol, or ethylene carbonate, propylene carbonate, and propylene glycol.
[Claim 11]
The superabsorbent polymer according to claim 9, wherein the carbonate-based compound is used in an amount of 0.4 to 2.5 parts by weight based on 100 parts by weight of the base resin, and the diol-based compound is used in an amount of 0.2 to 3.0 parts by weight based on 100 parts by weight of the base resin. A method for preparing the composition.
[Claim 12]
The method of claim 8, wherein the surface crosslinking reaction is performed at a temperature of 60 to 190°C.
[Claim 13]
The method according to claim 8, wherein the preparing of the base resin comprises polymerizing a monomer composition comprising an acrylic acid-based monomer having an acidic group and at least a portion of the acidic group neutralized, an internal crosslinking agent, and a polymerization initiator. forming a gel-like polymer; drying the hydrogel polymer; pulverizing the dried polymer; and classifying the pulverized polymer.
[Claim 14]
The method of claim 13, wherein the monomer composition does not contain a foaming agent.