KR20190076715A - Method for Preparing Super Absorbent Polymer - Google Patents

Abstract

The present invention relates to a super absorbent polymer and a preparation method thereof, capable of reducing energy in drying by reducing the amount water used in the reassembling of fines, reducing the dryer load by using a drying process dedicated to the reassembling of fines, and minimizing the deterioration of physical properties by preventing overdrying of a reassembled body of fines. In addition, it is possible to minimize the amount of re-ground fines generated by the use of a pulverizer dedicated to the reassembling of fines, and the process dedicated to the reassembling of fines can reduce the total circulation of processed fines.

Description

TECHNICAL FIELD The present invention relates to a method for preparing a superabsorbent resin,

More specifically, the present invention relates to a method for producing a superabsorbent resin, and more particularly, to a method for producing a superabsorbent resin composition, The present invention relates to a method for producing a highly water-absorbent resin.

Super Absorbent Polymer (SAP) is a synthetic polymer material having a function of absorbing moisture of about 500 to 1,000 times its own weight and has been put to practical use as a physiological tool. As well as hygiene products, are widely used as soil remediation agents for gardening, index materials for civil engineering and construction, sheets for seedling growing, freshness keeping agents in the field of food distribution, and fomentation materials.

The absorption mechanism of such a superabsorbent resin is characterized in that the absorption mechanism of the superabsorbent resin is a combination of the permeation pressure due to the difference in electrical attraction represented by the charge of the polymer electrolyte, the affinity between water and the polymer electrolyte, the molecular expansion due to the repulsion between the polymer electrolyte ions, . That is, the water absorbency of the water absorbent resin depends on the above-described affinity and molecular swelling, and the rate of absorption depends largely on the penetration pressure of the water absorbent polymer itself.

Much research has been conducted to improve the absorption rate of such a superabsorbent resin. For example, Korean Patent Laid-Open Publication No. 2014-0063457 discloses a method for producing a superabsorbent resin including a step of preparing a fine pulverized product using only fine powder and base water without an additive. However, There is a problem that the resin is lowered and the process is complicated and the efficiency is lowered. In addition, the fine powder that necessarily occurs in the production process of the superabsorbent resin is a factor of deterioration of the physical properties of the product. To solve this problem, there is a method of adding a fine powder at the time of polymerization. However, Thereby interfering with the polymerization and deteriorating the physical properties.

A method of reassembling the fine particles by using a separate re-granulator has been developed. This method is a method of making fine particles by mixing a fine powder and water at a certain ratio. For example, FIG. 1 is a process diagram schematically showing a method of manufacturing a superabsorbent resin by using a conventional fine particle remover and mixing it with normal particles to produce a superabsorbent resin. Referring to FIG. 1, a method for producing a superabsorbent resin using a conventional microfibrillated assembly is a method for producing a superabsorbent resin by a method in which a water-soluble ethylenically unsaturated monomer and a monomer composition containing a polymerization initiator are polymerized, The fine powders were mixed with water and reassembled to prepare a fine pulverized product, which was mixed with the hydrogel polymer or crude pulverized product, followed by drying, crushing, classification and surface crosslinking to prepare a superabsorbent resin. When the above-mentioned technique is used, when the water is used at a certain level or higher, the fine particles are sufficiently swollen in water to bind with other fine particles, and when they are dried, a level of microbaste assemblage is formed which is usable as a product. However, when water is used at a level below a certain level, the fine powders and water do not mix uniformly, forming nonuniform particles having different moisture contents. When this reassembly is dried, the reassembly having a relatively low water content is excessively dried, And the particle strength is weaker than that of the high-water-content fine aggregate or base resin. This raises the rate of occurrence of the funnel in the process, which leads to a decrease in the process stability and deterioration of the physical properties. In addition, it raises the fraction of the fine powder in the final product and increases the amount of the fine powder, It causes problems.

Thus, when the amount of water used for assembling the bonsai is lowered to a certain level or lower, the particle strength is improved through the pressing process to solve the problem caused by the decrease of the particle strength. However, when the bonsai assembly having a low water content is compressed, And the outer surface was hardened by the compression heat, so that the stem type microdispersing assembly which was not easy to dry in the micro bonsai assembly was discharged.

Korea Patent Publication No. 2014-0063457

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art as described above, and it is an object of the present invention to improve the drying efficiency of the stem type microdispersing assembly to improve the drying efficiency, And a method for manufacturing a highly water-absorbent resin.

According to an aspect of the present invention,

Subjecting a monomer composition comprising a water-soluble ethylenically unsaturated monomer and a polymerization initiator to thermal polymerization or photopolymerization to prepare a hydrogel polymer;

Drying and pulverizing the hydrogel polymer to classify the fine particles having a particle diameter of 150 mu m or less and the normal particles having a particle diameter of 150 mu m or more and 850 mu m or less;

Mixing the fine powder with water, and reassembling to prepare a fine pulverized product;

Compressing and cutting the pulverized pulverulent assembly to produce a pulverized pulverulent pulverulent assembly;

Drying and crushing the pressurized fine granulation assembly to classify the re-assembly fine particles having a particle size of 150 mu m or less and the re-assembly normal particles having a particle size of 150 mu m or more and 850 mu m or less; And

Mixing the remodeling normal particles with the normal particles;

And a method of producing a superabsorbent resin.

The method for producing a superabsorbent resin according to the present invention can reduce the amount of water used in the reassembly of fine powders, thereby reducing the energy during drying.

In addition, the strength of the fine pulverized product can be improved by using the pulverization re-assembly pressing process.

In addition, the load of the base resin dryer can be reduced by using the drying process dedicated to fine particle reassembly.

In addition, by using a drying process dedicated to fine particle reassembly, it is possible to prevent overdrying of the fine pulverized product, thereby minimizing deterioration of physical properties.

In addition, the use of the pulverizer for pulverization reassembly can minimize the amount of pulverized pulverized powder and reduce the total amount of pulverized pulverized pulverized pulverized pulverized product.

Fig. 1 is a schematic view showing a process of manufacturing a conventional superabsorbent resin.
2 is a schematic view showing a process of manufacturing a superabsorbent resin according to an embodiment of the present invention.
FIG. 3 is a photograph of a pressed differential powder assembly, which is compressed and cut by a chopper equipped with a blade and discharged through a discharge port, in the production of the fine powder compact according to Example 1-1.
FIG. 4 is a photograph of a pressurized fine powder disassembly assembly discharged through a discharge port after being compressed by a meat chopper not provided with a blade during the production of the fine powder compact according to Comparative Example 1-1.
FIG. 5 is a graph showing changes in temperature with respect to the pressed compacted disintegration assembly according to Example 1-1 and Comparative Example 1-1, when dried. FIG.
FIG. 6 is a graph showing changes in water content (M / C) of the pressed compacted disintegration assembly in Examples 1-1 and 1-1 according to the dryer position. FIG.
FIG. 7 is a photograph of the pressed compacting assembly obtained according to Example 1-2 with a scanning electron microscope. FIG.
FIG. 8 is a photograph of a pressed compact according to Comparative Example 1-2, observed with a scanning electron microscope. FIG.
9 is a photograph of a pressed compacting assembly obtained according to Comparative Example 1-3, observed with a scanning electron microscope.

The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprises", "comprising", or "having" are used to designate the presence of stated features, steps, components, or combinations thereof, and are not intended to preclude the presence of one or more other features, Components, or combinations thereof, as a matter of convenience, without departing from the spirit and scope of the invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Hereinafter, a method for producing a superabsorbent resin will be described in more detail according to a specific embodiment of the present invention.

A method of manufacturing a superabsorbent resin according to an embodiment of the present invention includes:

Polymerizing a monomer composition comprising a water-soluble ethylenically unsaturated monomer and a polymerization initiator to conduct thermal polymerization or photopolymerization to prepare a hydrogel polymer (Step 1);

Drying and pulverizing the hydrogel polymer to classify the fine particles having a particle size of 150 mu m or less and the normal particles having a particle diameter of 150 mu m or more and 850 mu m or less (step 2);

Mixing the fine powder with water and reassembling to prepare a fine pulverized product (step 3);

Compressing and cutting the pulverized pulverizer assembly to produce a pulverized pulverizer assembly (step 4);

Drying and crushing said pressurized fine granulation assembly to classify the reassembly fine particles having a particle size of 150 mu m or less and the re-assembly normal particles having a particle diameter of 150 mu m or more and 850 mu m or less (step 5); And

And mixing the remodeling normal particles with the normal particles (step 6).

As used herein, the term "polymer" or "polymer" in the present specification means that the water-soluble ethylenically unsaturated monomer is in a polymerized state and includes all the water content ranges, all the particle diameter ranges, all the surface cross- . Among the above polymers, a polymer having a moisture content (moisture content) of about 40% by weight or more and being in a state before drying after polymerization can be referred to as a hydrogel polymer. Further, a polymer having a particle diameter of 150 占 퐉 or less, more specifically, less than 150 占 퐉 may be referred to as a "fine powder ".

The "superabsorbent resin" means the polymer itself according to the context, or the polymer may be subjected to further processes such as surface crosslinking, fine particle reassembling, drying, crushing, classification, And the like.

2 is a schematic view showing a process of manufacturing a superabsorbent resin according to an embodiment of the present invention. FIG. 2 is an illustration for illustrating the present invention, but the present invention is not limited thereto. Referring to FIG. 2, the preparation steps of the superabsorbent resin will be described in detail below.

In the method for producing a superabsorbent resin of the present invention, step 1 is a step of producing a hydrogel polymer.

The hydrogel polymer may be prepared by subjecting a monomer composition comprising a water-soluble ethylenically unsaturated monomer and a polymerization initiator to thermal polymerization or photopolymerization.

The monomer composition which is a raw material of the superabsorbent resin includes a water-soluble ethylenically unsaturated monomer and a polymerization initiator.

The water-soluble ethylenically unsaturated monomer may be any monomer conventionally used in the production of a superabsorbent resin without any particular limitations. Here, at least one monomer selected from the group consisting of an anionic monomer and its salt, a nonionic hydrophilic-containing monomer and an amino group-containing unsaturated monomer and a quaternary car- bon thereof may be used.

Specific examples include (meth) acrylic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, 2- acryloylethanesulfonic acid, 2- methacryloylethanesulfonic acid, 2- (meth) acryloylpropanesulfonic acid, 2- Anionic monomers of (meth) acrylamido-2-methylpropanesulfonic acid and salts thereof; (Meth) acrylamide, N-substituted (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate or polyethylene glycol Non-ionic hydrophilic-containing monomer of (meth) acrylate; And at least one selected from the group consisting of unsaturated monomers containing an amino group of (N, N) -dimethylaminoethyl (meth) acrylate or (N, N) -dimethylaminopropyl (meth) .

More preferably, acrylic acid or a salt thereof, for example, an alkali metal salt such as acrylic acid or sodium salt thereof can be used. By using such a monomer, it becomes possible to produce a superabsorbent resin having superior physical properties. When the alkali metal salt of acrylic acid is used as a monomer, acrylic acid may be neutralized with a basic compound such as sodium hydroxide (NaOH).

The concentration of the water-soluble ethylenically unsaturated 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 the solvent of the superabsorbent resin, It may be an appropriate concentration considering time and reaction conditions. However, if the concentration of the monomer is excessively low, the yield of the superabsorbent resin may be low and economical efficiency may be deteriorated. On the other hand, if the concentration is excessively high, a part of the monomer may precipitate or the pulverization efficiency may be low Problems such as the like may occur and the physical properties of the superabsorbent resin may be deteriorated.

In the method for producing a superabsorbent resin of the present invention, the polymerization initiator used in polymerization is not particularly limited as long as it is generally used in the production of a superabsorbent resin.

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

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

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

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

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

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

According to an embodiment of the present invention, the monomer composition may further include an internal cross-linking agent as a raw material of the superabsorbent resin. As the internal crosslinking agent, a crosslinking agent having at least one functional group capable of reacting with the water-soluble substituent of the water-soluble ethylenically unsaturated monomer and having at least one ethylenic unsaturated group; Or a crosslinking agent having two or more functional groups capable of reacting with water-soluble substituents formed by hydrolysis of the water-soluble substituents and / or monomers of the monomers.

Specific examples of the internal crosslinking agent include bisacrylamide having 8 to 12 carbon atoms, bismethacrylamide, poly (meth) acrylate of polyol having 2 to 10 carbon atoms or poly (meth) allyl ether of polyol having 2 to 10 carbon atoms (Meth) acrylate, ethyleneoxy (meth) acrylate, propyleneoxy (meth) acrylate, glycerin diacrylate, At least one selected from the group consisting of glycerin triacrylate, trimethylol triacrylate, triallylamine, triaryl cyanurate, triallyl isocyanate, polyethylene glycol, diethylene glycol and propylene glycol can be used.

Such an internal crosslinking agent may be contained at a concentration of 0.01 to 0.5% by weight based on the monomer composition, so that the polymerized polymer may be crosslinked.

In the production method of the present invention, the monomer composition of the superabsorbent resin may further contain additives such as a thickener, a plasticizer, a storage stabilizer, and an antioxidant, if necessary.

The raw materials such as the above-mentioned water-soluble ethylenically unsaturated monomers, photopolymerization initiators, thermal polymerization initiators, internal cross-linking agents and additives can be prepared in the form of a monomer composition solution dissolved in a solvent.

The solvent which can be used at this time can be used without limitation of its constitution as long as it can dissolve the above-mentioned components. Examples thereof include water, ethanol, ethylene glycol, diethylene glycol, triethylene glycol, And examples thereof include alcohols such as ethylene 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, At least one selected from ether, toluene, xylene, butylolactone, carbitol, methylcellosolve acetate and N, N-dimethylacetamide can be used in combination.

The solvent may be included in the remaining amount of the monomer composition excluding the components described above.

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

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

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

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

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

According to one embodiment of the invention, a crude grinding process may optionally be further performed on the hydrogel polymer obtained above.

In this case, the pulverizer used in the coarsely pulverizing process is not limited in its structure, but may be a vertical pulverizer, a turbo cutter, a turbo grinder, a rotary cutter a crusher, a crusher, a chopper, and a disc cutter, which are selected from the group consisting of a mill, a mill, a cutter mill, a disc mill, a shred crusher, a crusher, a chopper and a disc cutter But it is not limited to the above example.

Wherein the coarse grinding step may be milled to a size of from about 2 to about 20 mm in diameter of the hydrogel polymer.

Coarse pulverization with a particle size of less than 2 mm is not technically easy due to the high water content of the hydrogel polymer, and may also result in agglomeration of the pulverized particles. On the other hand, when the grain size is larger than 20 mm, the effect of increasing the efficiency of the subsequent drying step may be insignificant.

Next, in the method for producing a superabsorbent resin according to one embodiment of the present invention, Step 2 is a step of drying and pulverizing the hydrogel polymer produced in Step 1 to classify fine particles into normal particles.

The drying step is carried out for the crude gelatinous polymer immediately after the polymerization without the coarse pulverization step in step 1 or the coarse pulverization step. The drying temperature of the drying step may be about 150 to about 250 ° C. If the drying temperature is lower than 150 ° C, the drying time becomes excessively long and the physical properties of the superabsorbent resin to be finally formed may deteriorate. When the drying temperature exceeds 250 ° C, only the polymer surface is excessively dried, And the physical properties of the finally formed superabsorbent resin may be deteriorated. Thus, preferably, the drying can proceed at a temperature of from about 150 to about 200 < 0 > C, more preferably from about 160 to about 180 < 0 > C.

On the other hand, in the case of drying time, it may proceed for about 20 to about 90 minutes, but is not limited thereto, considering process efficiency and the like.

The drying method in the drying step may be selected and used as long as it is usually used as a drying step of the hydrogel polymer. Specifically, the drying step can be carried out by hot air supply, infrared irradiation, microwave irradiation, ultraviolet irradiation, or the like. The water content of the polymer after such a drying step may be from about 0.1 to about 10% by weight.

Next, a pulverizing process is performed on the dried polymer obtained through such a drying step.

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

In order to control the physical properties of the superabsorbent resin powder which is finally produced after such a pulverization step, the polymer powder obtained after pulverization is generally classified according to the particle size. Preferably, the particles are classified into particles having a particle diameter of 150 mu m or less and particles having a particle diameter of more than 150 mu m and 850 mu m or less.

In the specification of the present invention, the fine particles having a particle size of less than a certain particle size, that is, about 150 탆 or less are referred to as superabsorbent polymer fine particles, SAP fine particles or fine powders, The particles are referred to as normal particles. The fine powder may be generated during the polymerization process, the drying process, or the pulverization step of the dried polymer. When the final product contains fine particles, it is difficult to handle and gel blocking phenomenon. It is preferable to exclude it from being included or reuse to become a normal particle.

As an example, the re-assembly process may be used to coagulate the fine particles to have a normal particle size. During the reassembly process, a reassembly process is generally performed in which the fine particles are agglomerated in a wet state in order to increase the cohesion strength. At this time, the higher the moisture content of the fine particles, the higher the cohesive strength of the fine powders, but the larger the re-assembly mass, the larger the mass of the re-assembled mass may cause problems in the process operation. Thereafter, it is often broken down again as a differential. In addition, the thus obtained fine pulverized material has lower physical properties such as CRC and AUP than normal particles, thereby causing a decrease in the quality of the superabsorbent resin.

Accordingly, in the method for producing a superabsorbent resin according to an embodiment of the present invention, Step 3 is a step of producing a fine pulverized product using the fine powder classified in Step 2 above.

Specifically, the fine powder having a particle diameter of 150 탆 or less classified in the above step 2 is mixed with water and reassembled to prepare a fine powder compact.

In this case, the water may be contained in an amount such that the fine powder can be reassembled in a wet state. Specifically, the water may be added in an amount of 10 to 150 parts by weight, preferably 10 to 80 parts by weight, May be 20 to 60 parts by weight. When the water content is less than 10 parts by weight, a small amount of water is evenly dispersed due to the rapid absorption rate of the fine particles in the mixing process of the fine particles. There is a possibility that the uniformity of the fine pulverizing assembly is lowered. In addition, when the water content of the fine pulverized product to be produced is decreased, a hard lump is formed during the subsequent pressing step, which may lower the stability of the pressing operation. If the water content exceeds 150 parts by weight, the tackiness of the bimetallic assembly increases during the mixing process, so that normal mixing can not be performed. In addition, there is a concern that the amount of water to be evaporated increases during the drying process, .

Further, according to one embodiment of the present invention, a water-soluble polymer may optionally be further used as an additive in mixing the fine powder and water.

Examples of the water-soluble polymer include synthetic polymers such as polyethylene glycol, polyethylene oxide, polyvinyl pyrrolidone, polyvinyl alcohol, polyacrylamide, polyacrylic acid, polystyrene sulfonic acid, polysilicic acid, polyphosphoric acid, Synthetic polymers such as acid, polyvinylphenol, polyvinylphenylsulfonic acid, polyethylenephosphoric acid, polyethylene amide, polyamine or polyamide amine; Or non-synthetic polymers such as starch, rubber, cellulose, etc., and any one or a mixture of two or more thereof may be used. These water-soluble polymers have the function of promoting the lubrication action of the microdispersing agent in the mixing mixer and improving the mixing stability and uniformity. Of the above water-soluble polymers, polyethylene glycol may be more preferable due to chemical stability, harmlessness to human body, excellent dispersion / lubrication effect, and economical characteristics.

The polyethylene glycol may have a weight average molecular weight of 2,000 to 200,000 g / mol, more preferably 4,000 to 100,000 g / mol. If the molecular weight of the polyethylene glycol is less than 2,000 g / mol, the lubricating action may be deteriorated. If the molecular weight exceeds 200,000 g / mol, the solubility in water may be lowered.

The water-soluble polymer may be used in an amount of 0.01 to 5 parts by weight, more preferably 0.01 to 1 part by weight, based on 100 parts by weight of the fine powder. When the content of the water-soluble polymer is less than 0.01 part by weight, it is difficult to obtain the effect of improving the mixing stability and uniformity of the fine pulverized product due to the use of the additive. When the content of the water-soluble polymer is more than 1 part by weight, There is a fear of deterioration in performance.

When the additive is further used, according to one embodiment of the present invention, mixing of water and an additive to prepare an additive aqueous solution, and mixing the additive into the additive aqueous solution may improve mixing stability and uniformity Can be obtained.

Next, in the method for manufacturing a superabsorbent resin according to an embodiment of the present invention, Step 4 is a step of manufacturing a pressed compacted assembly using the fine pulverized material prepared in Step 3 above.

The pressurized fine granulation assembly may be produced in the form of a secondary granule in the form of a stem by squeezing and cutting the fine powder preparation produced in step 3 above.

The crimping process for the finely pulverized assembly may be performed using a conventional extruder such as a meat chopper, and the cutting process may be performed at a rear end of the pressing process, for example, at a hole outlet of a hole plate Or by a cutter such as a blade or a scrapper.

For example, in the case of using a meat chopper provided with a blade having two blades in a hole discharge port, first, the pulverizer assembly is pressed by the meat chopper, And is cut into a particle shape by the blade located on the plate discharge port side. At this time, the crushed pulverized granules cut into granules are re-combined due to the tackiness at the cut part and become secondary particles of stem form. In the method of manufacturing a fine powder compact using only a conventional meat chopper, the pressed fine powder compact is discharged in the form of a stem. At this time, the discharged compressed fine powder compact is a single particle having a stem shape. On the other hand, in the case of the present invention, a plurality of primary particles cut into a single particle are secondary particles recombined into a stem shape by adhesion at a cut surface. Due to this difference, in the conventional method, the drying speed is slow and the drying efficiency is low because the drying is progressed on the surface of the stem type particle during the subsequent drying step. On the other hand, in the present invention, the particles forming the stem- So that the primary particles are separated into a single particle. As a result, the drying speed can be increased and the drying efficiency can be increased.

Next, in the method for producing a superabsorbent resin according to an embodiment of the present invention, step 5 is a step of drying and crushing the compressed granulated compacted material, Quot; fun ") and re-assembly normal particles.

The drying process may be performed using a conventional dryer, but may be performed using a paddle dryer or a forced circulation dryer according to one embodiment of the present invention. When the drying process is carried out in these dryers, the secondary granulated compressed granules are flowed easily, for example, in the case of the paddle-type dryer, due to the force generated when the paddle flows, It can be primary granulated. As a result, the drying speed and drying efficiency for the crimped fine pulverized material can be further increased.

Also, the drying step may be performed at a temperature of 120 to 220 ° C. If the temperature is lower than 120 deg. C in the drying step, the drying time becomes longer. If the temperature exceeds 220 deg. C, the properties of the fine pulverized product may deteriorate and the property may deteriorate. More preferably at a temperature of 150 to 200 DEG C, so that the moisture content in the fine pulverized material is 1 wt% or less.

In addition, it is preferable to increase the temperature to the latter stage of the drying process within the above-mentioned temperature range, since the drying efficiency can be further increased. Concretely, it is more preferable that the temperature of the dryer inlet is 120 to 160 ° C at the beginning of the drying process, and the temperature of the latter stage of the drying process, specifically, the temperature of the rear stage outlet of the dryer is 150 to 200 ° C.

The constitution of the heating means for drying in the drying step is not limited. Specifically, the heating medium can be supplied or heated directly by means such as electricity, but the present invention is not limited to the above-described examples. Specific examples of the heat source that can be used include steam, electricity, ultraviolet rays, and infrared rays, and heated heat fluids and the like may also be used.

In addition, the drying step may be carried out such that the water content in the dried pressed pulverulent assembly is 1% by weight or more, more specifically 1 to 2% by weight. If the water content in the dried pressed compacted granules is less than 1% by weight, the properties of the fine pulverized product may be deteriorated.

By the drying process as described above, the pulverized pulverized granules in the form of a stem are primary-granulated in the form of a single particle.

The crushed fine granulation product obtained after the drying process has a high cohesive strength due to a low proportion of re-crushing after pulverization.

Specifically, the crushable fine pulverized material is preferably pulverized in such a manner that the weight ratio of pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverized pulverulent pulverulent pulverized By weight or less.

The compacted pulverized fine granulation product obtained after pulverization may be a pulverized pulverized pulverized pulverulent pulverulent pulverulent pulverulent pulverulent pulverulent pulverulent pulverulent pulverulent pulverulent pulverulent pulverulent pulverulent pulverulent pulverulent pulverulent pulverulent pulverulent pulverulent pulverulent pulverulent pulverulent pulverulent pulverulent When classified into particles, the proportion of particles having a diameter of more than 600 μm and 850 μm or less may be 30% by weight or more, and more specifically, 33 to 40% by weight.

It is also preferred that the compression bonded CRC of 33.0 to 39.0 g / g measured according to the EDANA method WSP 241.3 of the pressed separator assembly having a particle size of more than 300 μm but not more than 600 μm and the absorption rate by the vortex method of 40 Sec. In the measurement by the above-mentioned vortex method, 50 ml of saline was put into a 100 ml beaker together with a magnetic stirring bar, and the stirring speed of the magnetic stirring bar was set to 600 rpm using a stirrer. To the stirred saline was added 2.0 g of fine- The time is measured at the same time as putting, and the time (unit: second) taken until the vortex disappears in the beaker is measured as the vortex time. The lower limit value of the absorption rate is not particularly limited, but may be about 20 seconds or more, or about 30 seconds or more.

In addition, the pressed compacted disintegration assembly has a water content of 30% or less and can exhibit excellent particle strength even though it has such a low water content.

Next, the dried compacted pulverized product is pulverized and classified.

The pulverization may be carried out such that the dried pressed pulverized pulverulent granulation product has a particle diameter of 150 μm or more and 850 μm or less. The pulverizer used for crushing with such a particle size is specifically a pin mill, a hammer mill, a screw mill, a roll mill, a disc mill, A jog mill, or the like may be used, but the present invention is not limited to the above examples.

In order to control the physical properties of the superabsorbent resin powder which is finally produced after such a pulverization step, the polymer powder obtained after pulverization is generally classified according to the particle size. Preferably a funnel having a particle diameter of 150 mu m or less and a re-assembly normal particle having a particle diameter of 150 mu m or more and 850 mu m or less.

Next, in the method for producing a superabsorbent resin according to an embodiment of the present invention, Step 6 is a step of mixing the re-assembly normal particles classified in Step 5 with the normal particles prepared in Step 2 above.

Specifically, the funnel having a particle size of not more than 150 mu m after classification in the step 5 is circulated to the differential reassembly process step, and the re-assembly normal particle having a particle size of more than 150 mu m and not more than 850 mu m is recycled to the Mix with normal particles. In addition, after the mixing step, the surface cross-linking step may be selectively performed by further introducing the remodeling normal particles and the normal particles into the surface cross-linking mixer.

The surface cross-linking is a step of increasing the cross-linking density near the surface of the superabsorbent polymer particle in relation to the cross-linking density inside the particle. Generally, the surface cross-linking agent is applied to the surface of the superabsorbent resin particles. Thus, this reaction takes place on the surface of the superabsorbent resin particles, which improves the crosslinkability on the surface of the particles without substantially affecting the interior of the particles. Thus, the surface cross-linked superabsorbent resin particles have a higher degree of crosslinking in the vicinity of the surface than in the interior.

At this time, the surface cross-linking agent is not limited as long as it is a compound capable of reacting with a functional group contained in the polymer.

Preferably, in order to improve the properties of the resulting superabsorbent resin, a polyhydric alcohol compound as the surface crosslinking agent; Epoxy compounds; Polyamine compounds; Halo epoxy compounds; A condensation product of a haloepoxy compound; Oxazoline compounds; Mono-, di- or polyoxazolidinone compounds; Cyclic urea compounds; Polyvalent metal salts; And an alkylene carbonate compound can be used.

Specific examples of the polyhydric alcohol compound include mono-, di-, tri-, tetra- or polyethylene glycol, monopropylene glycol, 1,3-propanediol, dipropylene glycol, 2,3,4-trimethyl- - pentanediol, polypropylene glycol, glycerol, polyglycerol, 2-butene-1,4-diol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,2-cyclohexane dimethanol, and the like.

Examples of the epoxy compounds include ethylene glycol diglycidyl ether and glycidol. Examples of the polyamine compounds include ethylene diamine, diethylene triamine, triethylene tetramine, tetraethylene pentaamine, pentaethylene hexamine , Polyethyleneimine, and polyamide polyamines can be used.

As the haloepoxy compound, epichlorohydrin, epibromohydrin, and? -Methyl epichlorohydrin may be used. On the other hand, as the mono-, di- or polyoxazolidinone compounds, for example, 2-oxazolidinone and the like can be used.

As the alkylene carbonate compound, ethylene carbonate and the like can be used. These may be used alone or in combination with each other. On the other hand, in order to increase the efficiency of the surface cross-linking step, it is preferable to use at least one polyhydric alcohol compound among these surface cross-linking agents, more preferably a polyhydric alcohol compound having 2 to 10 carbon atoms.

The amount of the surface crosslinking agent to be added may be appropriately selected according to the kind of the surface crosslinking agent to be added and the reaction conditions, but is usually about 0.001 to about 5 parts by weight, preferably about 0.01 to about 5 parts by weight, 3 parts by weight, more preferably about 0.05 to about 2 parts by weight, may be used.

If the content of the surface cross-linking agent is too small, surface cross-linking reaction hardly occurs. If the amount of the surface cross-linking agent is more than 5 parts by weight based on 100 parts by weight of the polymer, excessive absorption of the surface cross- .

By heating the polymer particles to which the surface cross-linking agent has been added, the surface cross-linking reaction and drying can be performed at the same time.

The temperature raising means for the surface cross-linking reaction is not particularly limited. A heating medium can be supplied, or a heating source can be directly supplied and heated. At this time, as the type of usable heat medium, it is possible to use a heated fluid such as steam, hot air or hot oil. However, the present invention is not limited thereto, and the temperature of the heat medium to be supplied can be controlled by means of heat medium, It can be appropriately selected in consideration of the target temperature. On the other hand, as a heat source to be directly supplied, a heating method using electricity or a heating method using gas may be mentioned, but the present invention is not limited to the above-mentioned examples.

After the surface cross-linking, the surface cross-linked fine particles having a particle diameter of not more than 150 mu m and the surface cross-linked normal particles having a particle diameter of not less than 150 mu m and not more than 850 mu m, The surface-crosslinked particles can be commercialized and reused.

The superabsorbent resin prepared by the above-mentioned method is a polymer obtained by polymerizing a water-soluble ethylenically unsaturated monomer containing an acidic group and neutralizing at least a part of the acidic groups, A superabsorbent resin having a surface cross-linked compressed pulverized material assembly and having a retention capacity (CRC) of 33.0 to 39.0 g / g measured according to EDANA method WSP 241.3; A 0.7 psi pressure sorption capacity (AUP) of 20.0 to 25.0 g / g measured according to EDANA method WSP 241.3; An absorption rate by a vortex method is 100 seconds or less, and an apparent density (B / D) is 0.6 to 0.7 g / cm ³ .

In the superabsorbent resin of one embodiment, the polymer is obtained by polymerizing a water-soluble ethylenically unsaturated monomer having an acidic group and at least a part of which is neutralized. .

Further, in the superabsorbent resin of one embodiment of the present invention, the fine particles refer to particles having a particle diameter of not more than 150 탆 in the polymer, and any step of the superabsorbent resin, For example, the present invention can cover all of those occurring in a polymerization process, a drying process, a pulverizing process of a dried polymer, or a surface cross-linking process.

The pressurized fine pulverization assembly may be a pulverized pulp that has been reassembled by mixing water and then re-assembling the pulverized pulverized pulverized pulp by further mixing the water-soluble polymer. A more detailed description of the water-soluble polymer is the same as that described above in the preparation method of a superabsorbent resin.

The superabsorbent resin that has been surface cross-linked with the re-assembled pressured pulverulent assembly as described above has a retention capacity (CRC) of about 33.0 to about 39.0 g / g, or about 34.0 to about 38.0 g / g, as measured according to EDANA method WSP 241.3 Lt; / RTI > Also, the 0.7 psi pressure absorption capacity (AUP) measured according to EDANA method WSP 241.3 may be about 20.0 to about 25.0 g / g, or about 21.0 to about 25.0 g / g.

The absorption rate of the superabsorbent resin by the vortex method may be about 100 seconds or less, or about 95 seconds or less. The measurement by the vortex method is the same as that described above except that a superabsorbent resin is used in place of the fine pulverizing agent.

Hereinafter, the present invention will be described in more detail based on examples. However, the following examples are illustrative of the present invention, and the present invention is not limited by the following examples. In the following Examples and Comparative Examples, "%" and "part" representing the content are based on weight unless otherwise specified.

<Examples>

Preparation of superabsorbent resin particles

Production Example 1

100 g of acrylic acid, 0.3 g of polyethylene glycol diacrylate as a crosslinking agent, 0.033 g of sodium persulfate as an initiator, 38.9 g of caustic soda (NaOH) and 103.9 g of water to prepare a monomer mixture having a monomer concentration of 50% by weight Respectively.

Then, the monomer mixture was placed on a continuously moving conveyor belt, irradiated with ultraviolet light (irradiation amount: 2 mW / cm ² ), and UV polymerization was carried out for 2 minutes to obtain a hydrogel polymer.

The hydrogel polymer was pulverized with a meat chopper (hole size: 10 mm) to obtain a crude pulverized gel polymer. Dried in a hot-air dryer at a temperature of 170 ° C for 1 hour, pulverized with a pin mill and classified with a standard mesh of ASTM standard to obtain a mixture of normal particles having a particle size of 150 μm or more and 850 μm or less and particles having a particle size of 150 μm or less Fine particles were obtained.

Production examples of pulverulent reassembly

Example 1-1

12 kg / h of a fine powder having a particle diameter of 150 μm or less and 0.5 wt% of polyethylene glycol (PEG) (6,000 g / mol) were dissolved in the superabsorbent resin prepared in Preparation Example 1 at a flow rate of 4.8 kg / To a continuous mixing mixer while operating at a stirring speed of 1,500 rpm to prepare a fine powder compact. The above-mentioned bonsai assembly was put into a meat chopper equipped with a blade having two cutting edges on a hole plate discharge port, and pressed. The pressed granules were cut into particles by the blade, and some of the particles were recombined into a stalactite form due to the tackiness of the cut part. This was put into a forced circulation type dryer and dried at 180 ° C for 60 minutes to recover the pressed granulation product.

Comparative Example 1-1

12 kg / h of a fine powder having a particle diameter of 150 μm or less and 0.5 wt% of polyethylene glycol (PEG) (6,000 g / mol) were dissolved in the superabsorbent resin prepared in Preparation Example 1 at a flow rate of 4.8 kg / To a continuous mixing mixer while operating at a stirring speed of 1,500 rpm to prepare a fine powder compact. The pulverized re-assembly was put in a forced circulation type dryer without being squeezed, and dried at 180 ° C for 60 minutes to recover the pulverized re-assembly.

Comparative Example 1-2

The fine powder having a particle diameter of 150 mu m or less and the water were supplied to a continuous mixing mixer at a flow rate of 14.4 kg / h and the mixture was operated at a stirring speed of 1,500 rpm to prepare a fine powder compact . The pulverized re-assembly was put in a forced circulation type dryer without being squeezed, and dried at 180 ° C for 60 minutes to recover the pulverized re-assembly.

Example 2

12 kg / h of a fine powder having a particle diameter of 150 μm or less and 0.5 wt% of polyethylene glycol (PEG) (6,000 g / mol) were dissolved in the superabsorbent resin prepared in Preparation Example 1 at a flow rate of 4.8 kg / To a continuous mixing mixer while operating at a stirring speed of 1,500 rpm to prepare a fine powder compact.

The fine pulverization assembly was put into a hole plate discharge port by means of a meat chopper equipped with a blade having two cutting blades, and pressed. The pressed granules were cut into particles by the blade, and some of the particles were recombined into a stalactite form due to the tackiness of the cut part. This was continuously poured into a paddle-type dryer having an internal volume of 77 L, a total length of 180 cm and a paddle diameter of 16 cm, followed by drying at 180 ° C. As the drying process progressed inside the dryer, the stem pressurized pulverized pulverulent assembly was pulverized into a particle shape by the paddle flow. Meanwhile, the temperature of the stem type microdispersing assembly in the dryer in the initial stage of the dryer was 120 ° C, and the temperature of the downstream stage of the dryer was 173 ° C. In addition, the water content of the dried pre-pressurized fine granule was 27.5 wt%, the water content of the final dried product was 1.4 wt%, and the position of the dryer indicating the moisture content of the dried product was 5 wt% or less was found to be within 80 to 120 cm. The residence time of the pressurized differential ash assembly in the section was found to be 0.92 hours.

Comparative Example 2

The fine pulverizing assembly was mixed, compressed and dried in the same manner as in Example 1, except that the pulverized pulverizer was compressed under the condition that there was no blade on the hole plate outlet of the meat chopper. In the absence of the blade, the crimped fine granulation assembly was discharged in the form of a stem. This was continuously poured into a paddle-type dryer having an internal volume of 77 L, a total length of 180 cm and a paddle diameter of 16 cm, followed by drying at 180 ° C. Inside the dryer, the stem was crushed and crushed into granules as the stem pressurized pulverization assembly was dried. The temperature inside the dryer at the initial stage was 121 ° C, and the temperature at the downstream end of the dryer was 170 ° C. The moisture content of the dried pre-pressurized fine pulverized product is 29.6% by weight, and the moisture content of the final dried product is 3.5% by weight. The position of the dryer indicating that the water content of the dried material was 5 wt% or less was found to be within 120 to 150 cm. The residence time of the crushed differential ash assembly in the section was 1.42 hours.

Production Example of Superabsorbent Resin

Example 3

The compacted pulverized particulate material prepared in Example 1-1 was pulverized by a roll mill and then classified with a standard mesh of ASTM standard to obtain a re-assembly fine powder having a particle size of 150 mu m or less and a remanufactured normal particle having a particle diameter of 150 mu m or more and 850 mu m or less Respectively.

0.2 g of poly (ethylene glycol) diglycidyl ether, 5 g of methanol, 4 g of water, 4 g of silica airgel (manufactured by Wako Pure Chemical Industries, Ltd.) were added to 100 g of the mixture of the classified normal particles and the normal particles prepared in Preparation Example 1 at a weight ratio of 20: (AeroZelTM, JIOS), and then subjected to a surface cross-linking reaction at a temperature of 180 DEG C for 60 minutes to obtain a final superabsorbent resin.

Comparative Example 3-1

A superabsorbent resin was obtained in the same manner as in Example 3, except that the fine powder compacts prepared in Comparative Example 1-1 were used instead of the fine powder compacts prepared in Example 1-1.

Comparative Example 3-2

A superabsorbent resin was obtained in the same manner as in Example 3, except that the fine powder compacts prepared in Comparative Example 1-2 were used in place of the fine powder compacts prepared in Example 1-1.

<Experimental Example 1>

Table 1 shows the results of particle size distribution after milling and classification in order to grasp the fracture strength of the fine pulverized product according to Example 1-1 and Comparative Examples 1-1 and 1-2. .

Particle size distribution Example 1 Comparative Example 1-1 Comparative Example 1-2 weight% weight% weight% > 850 μm 2.2 0.6 0.7 Below 850 μm - above 600 μm 33.7 24.8 32 600 μm or less -300 μm or more 41.3 36.1 44.5 300 μm or less - greater than 150 μm 13.3 18 15 ? 150 m 9.5 20.5 7.9

As a result of the experiment, the microparticulate assembly of Comparative Example 1-2, in which the water consumption is relatively high, has a funnel fraction of 7.9% by weight, but the microparticle assembly of Comparative Example 1-1, 20.5% by weight, which is 2.6 times higher than that of the other samples. However, the fine pulverized product of Example 1 in which the meat chopper was squeezed exhibited a crushing strength similar to that of the fine bonsai assembly of Comparative Example 1-2, with a funneling rate of 9.5% by weight.

<Experimental Example 2>

In the production of the pressed separator assembly according to Example 1-1 and Comparative Example 1-1, the compressed separator assembly discharged through the discharge port of the meat chopper was observed. The results are shown in Figs. 3 and 4. Fig.

As a result of observation, the fine powder compact of Comparative Example 1-1 pressed through a mitochondrion not provided with a blade was discharged in a continuous streak form, whereas the fine powder compact of Example 1-1, which was pressed through a meat chopper equipped with a blade, The pulverized re-assembly was a secondary granulation in the form of pulverized particles through the re-assembly of the pulverized primary granules.

<Experimental Example 3>

The dryer temperature and the water content of the dried material were measured according to the distance from the inlet of the dryer in the preparation of the finely divided product according to Example 2 and Comparative Example 2, and the results are shown in Table 2 and FIGS. 5 and 6.

Distance from dryer inlet (cm) 0 20 50 80 120 150 180 Example 2 Chopper blade available Dryer temperature
(° C) - 120 145 158 171 173 - Dry matter moisture content (% by weight) 27.5 16.34 10.48 7.93 3.48 2.64 1.37 Comparative Example 2 No chopper blade Dryer temperature
(° C) - 121 140 147 159 170 - Dry matter moisture content (% by weight) 29.58 15.98 14.51 11.42 7.74 3.78 3.48

As a result of the experiment, the drying speeds of the pressed separator assemblies of Example 2 and Comparative Example 2 were similar regardless of the presence or absence of the chopper blades at the initial stage of drying. However, in Example 2 using the chopper blade from 20 cm 2, the drying rate was faster and the water content was remarkably decreased. The results are as follows. In the case of Example 2, the pressed compacted granules are cut into particles by the blade provided in the chopper, and the cut particles are discharged in the form of a re-combined stem due to the tackiness at the cut portion. This is because the paddle flow during the drying process increased the speed of pulverization into particulate matter. On the other hand, in the case of Comparative Example 2, the pulverized pulverization speed into the grain phase on the stem was slower than that of Example 2, because the pulverized fine pulverized material assembly was introduced into the dryer in a straight line without cutting by the meat chopper.

<Experimental Example 4>

In order to evaluate the physical properties of the crimped fine pulverized material, the pressed pulverulent pulverized product prepared in Example 1 and Comparative Examples 1-1 and 1-2 was classified and pressed compacted particles having a particle diameter of 300 mu m or more and 600 mu m or less The properties of the assemblies were measured by the following methods, and the results are shown in Table 3.

(1) The shape of the crimped fine particle assembly: The particle shape was observed with the naked eye.

(2) CRC (Centrifugal Retention Capacity)

The compressive fineness assemblies prepared in Example 1 and Comparative Examples 1-1 and 1-2 were measured for retention capacity. The measurement of water storage capacity was based on EDANA method WSP 241.3. 0.2 g of a specimen having a particle diameter of 300 탆 or more and 600 탆 or less among the prepared fine powder preparations is placed in a tea bag and precipitated in 0.9% saline solution for 30 minutes. After dehydration for 3 minutes with a centrifugal force of 250G (gravity), the amount W ₂ (g) of saline solution absorbed was measured. In addition, the mass W ₁ (g) at that time was measured after performing the same operation without using the pressed differential pulverization assembly.

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

[Equation 1]

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

In the above equation 1,

W ₀ (g) is the initial weight (g) of the crimped fine particle assembly,

W ₁ (g) is the weight of the device after dehydration at 250 G for 3 minutes using a centrifuge without using a crimped fine powder assembly,

W ₂ (g) was obtained by immersing and compressing the pressurized pulverization assembly in 0.9 wt% physiological saline at room temperature for 30 minutes and then dehydrating the powder at 250 G for 3 minutes using a centrifuge, It is the weight of the device.

(3) Absorption rate (Vortex)

Absorption rates were measured on the pressed separator assembly produced in Example 1 and Comparative Examples 1-1 and 1-2. The absorption rate was measured by placing 50 ml of saline in a 100 ml beaker with a magnetic bar. The agitation speed was set to 600 rpm using a stirrer. 2.0 g of the pressurized fine powder granules were put into the stirred saline solution and the time was measured. The time measurement was completed at the point when the vortex disappears in the beaker.

Example 1
(Moisture content 28.6% crush differential redispersibility) Comparative Example 1-1
(Moisture content 28.6% differential reassembly) Comparative Example 1-2
(Moisture 54.5% differential redispersion) Shape of crimped differentials assembly Dense particle shape Mixture of dense and individual particles Dense particle shape CRC (g / g) 38.1 37.3 40.0 Vortex (sec) 40 37 47

The results are shown in Table 3. Referring to Table 3, in the case of the pressed separator assembly of Example 1 in which the microfine particle reassembling process was carried out according to the manufacturing method of the present invention, physical properties such as water retention capacity and absorption rate, 2, respectively.

<Experimental Example 5>

In order to evaluate the physical properties of the superabsorbent resin including the fine pulverized product due to the change in the fine pulverization reassembling process, the physical properties of the superabsorbent resin prepared in Example 3 and Comparative Examples 3-1 and 3-2 were evaluated in the above Experiments 4, and the results are shown in Table 4.

(1) Abrasion Resistance (CRC) and Absorption Rate (Vortex): The same procedure as in Example 1 was carried out except that the superabsorbent resin prepared in Example 3 and Comparative Examples 3-1, The water retention capacity and the absorption rate were measured in the same manner as in Example 4, respectively.

(2) Absorption under pressure (AUP)

A 400 mesh wire mesh made of stainless steel was attached to the bottom of a plastic cylinder having an inner diameter of 60 mm. 0.90 g of the superabsorbent resin according to Example 1 and Comparative Examples 1-1 and 1-2 was uniformly sprayed onto the iron mesh under the conditions of room temperature and 50% humidity, and a load of 4.83 kPa (0.7 psi) The pistons which can be uniformly applied are slightly smaller than the outer diameter of 60 mm, so that there is no gap between the inner wall of the cylinder and the upward and downward movements are not disturbed. At this time, the weight Wa (g) of the device was measured. A glass filter having a diameter of 90 mm and a thickness of 5 mm was placed inside a Petro dish having a diameter of 150 mm and a physiological saline solution composed of 0.90% by weight sodium chloride was made to have the same level as the upper surface of the glass filter. And a filter paper having a diameter of 90 mm was placed thereon. The measuring device was placed on the filter paper and the liquid was absorbed under load for 1 hour. After one hour, the measuring device was lifted and its weight Wb (g) was measured. Then, the pressure absorption ability was calculated from Wa and Wb according to the following equation.

&Quot; (2) &quot;

AUP (g / g) = [Wb (g) - Wa (g)] /

(3) Bulk density (B / D)

100 g of the superabsorbent resin prepared in Example 3 or Comparative Examples 3-1 and 3-2 was flowed through a standard fluidity measuring device orifice into a 100-ml volume container, and the superabsorbent resin was shaved so as to be horizontal, After adjusting the volume of the superabsorbent resin to 100 ml, only the superabsorbent resin except for the container was weighed. The apparent density corresponding to the weight of the superabsorbent resin per unit volume was obtained by dividing the weight of the superabsorbent resin by the volume of the superabsorbent resin (100 ml).

Example 3 Comparative Example 3-1 Comparative Example 3-2 CRC (g / g) 34.8 35.4 34.6 AUP (0.7 psi) 24.1 23.0 26.4 ^{B / D (g / cm 3} ) 0.63 0.62 0.64 Vortex (sec) 75 55 79

Referring to Table 4, in the case of the superabsorbent resin of Example 3 in which the fine particle reassembling process was carried out according to the production method of the present invention, the superabsorbent resin exhibited an excellent absorption ability equal to or higher than that of Comparative Examples 3-1 and 3-2 .

Claims (14)

Subjecting a monomer composition comprising a water-soluble ethylenically unsaturated monomer and a polymerization initiator to thermal polymerization or photopolymerization to prepare a hydrogel polymer;
Drying and pulverizing the hydrogel polymer to classify the fine particles having a particle diameter of 150 mu m or less and the normal particles having a particle diameter of 150 mu m or more and 850 mu m or less;
Mixing the fine powder with water, and reassembling to prepare a fine pulverized product;
Compressing and cutting the pulverized pulverulent assembly to produce a pulverized pulverulent pulverulent assembly;
Drying and crushing the pressurized fine granulation assembly to classify the re-assembly fine particles having a particle size of 150 mu m or less and the re-assembly normal particles having a particle size of 150 mu m or more and 850 mu m or less; And
And mixing the remodeling normal particles with the normal particles.
The method according to claim 1,
Wherein the water is used in an amount of 10 to 150 parts by weight based on 100 parts by weight of the fine powder.
The method according to claim 1,
Wherein a water-soluble polymer is further added when the fine powder and water are mixed.
The method of claim 3,
The water-soluble polymer may be at least one selected from the group consisting of polyethylene glycol, polyethylene oxide, polyvinyl pyrrolidone, polyvinyl alcohol, polyacrylamide, polyacrylic acid, polystyrene sulfonic acid, polysilicic acid, polyphosphoric acid, polyethylene sulfonic acid, Wherein the hydrophilic resin comprises at least one selected from the group consisting of phenol, polyvinylphenylsulfonic acid, polyethylenephosphoric acid, polyethyleneamide, polyamine, polyamide amine, starch, rubber and cellulose.
The method of claim 3,
Wherein the water-soluble polymer is polyethylene glycol.
The method of claim 3,
Wherein the water-soluble polymer is a polyethylene glycol having a weight average molecular weight of 2,000 to 200,000 g / mol.
The method of claim 3,
Wherein the water-soluble polymer is added in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the fine powder.
The method according to claim 1,
Wherein said pressing is performed by an extruder.
The method according to claim 1,
Wherein the cutting is performed by a blade or a scriper.
The method according to claim 1,
Wherein said pressurized fine particle dispersion assembly is a secondary particle in which a plurality of primary particles cut into a single particle shape are re-combined into a stem shape by adhesion on a cut surface.
The method according to claim 1,
Wherein the drying on the pressurized fine granulation assembly is performed at 120 to 220 캜.
The method according to claim 1,
The drying of the pressurized pulverulent assembly is carried out at a temperature of 120 to 160 ° C. in the initial stage of drying and at a temperature of 150 to 200 ° C. in the latter stage of drying,
Wherein the temperature at the latter stage of drying is higher than that at the beginning of the drying.
The method according to claim 1,
Wherein the drying on the pressurized fine granulation assembly is performed using a paddle-type dryer or a forced circulation type dryer.
The method according to claim 1,
Further comprising the step of cross-linking the mixture of the normal particles and the remanufactured normal particles.

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