JP2022175201A - Method for producing super absorbent polymer - Google Patents

Abstract

To provide a method for producing a super absorbent polymer which enables super absorbent characteristics to be stabilized for a longer period of time by a crosslinking reaction performed at a lower temperature and/or in a shorter period of time.SOLUTION: A method for producing a super absorbent polymer, comprises: preparing a salt (I) of a copolymer of isobutylene and maleic anhydride and an alkaline substance, a catalyst (II) for a crosslinking reaction, and a crosslinking agent (III) which is a polyfunctional compound having two or more functional groups; and performing a crosslinking reaction of making the salt (I) crosslink by the crosslinking agent (III) in the presence of the catalyst (II). Preferably, the preparation includes preparing an aqueous solution comprising the salt (I), the catalyst (II), and the crosslinking agent (III) under heating, and the crosslinking reaction includes producing a solid matter by drying the aqueous solution, and performing the crosslinking reaction by subjecting the solid matter produced to a heat treatment.SELECTED DRAWING: None

Description

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

Superabsorbent resin has an amazing water absorption capacity, i.e., it absorbs a large amount of water instantly when it comes into contact with water, and once it has absorbed water, it does not separate even if some pressure is applied. Sanitary materials such as diapers, soil conditioners, civil engineering chemicals, sealants, optical fiber water supply prevention tapes, chemical warmers, roofing materials, cat litter, casting cement, deodorants, fragrances, detergents, abrasives, heat storage materials , cold insulators, etc. (see paragraph 0002 of the specification of Patent Document 1). In particular, Patent Literatures 1, 2, 3, and 4 disclose superabsorbent resins improved to satisfy practical salt water resistance, wet heat resistance, and durability, and methods for producing the same.

However, in the conventional method for producing a super absorbent polymer, there is a problem that the cross-linking reaction for forming the super absorbent polymer takes a long time. Moreover, even after the desired high water absorption property is obtained, the cross-linking reaction progresses slowly, resulting in the problem that the water absorption property of the super absorbent resin is not stable. If the cross-linking reaction proceeds excessively, the resin will be formed and the amount of water absorption will decrease, and when pressure is applied to the super absorbent resin that has absorbed water, water will seep out, which is a problem of partial deterioration.

JP-A-57-73007 JP-A-56-36504 JP-A-7-292023 JP-A-5-222368

The present invention has been made in view of the above problems. An object of the present invention is to provide a method for producing a water absorbent resin.

In order to achieve the above object, a first aspect of the present invention provides a method for producing a super absorbent resin, comprising: a salt (I) of a copolymer of isobutylene and maleic anhydride and an alkaline substance; and a catalyst (II) for a cross-linking reaction, and a cross-linking agent (III) which is a polyfunctional compound having two or more functional groups, and adding the salt (I) to the catalyst (II). causing a cross-linking reaction to cross-link with the cross-linking agent (III) in the presence of the cross-linking agent (III).

According to this configuration, the cross-linking reaction is performed in the presence of the catalyst, so that the cross-linking reaction can be performed at a lower temperature and/or in a shorter time to obtain a super absorbent resin having desirable high water absorbency. Moreover, the high water absorption property of the resulting super absorbent resin is stable over a longer period of time.

A second aspect of the present invention is a method for producing a superabsorbent polymer according to the first aspect, wherein the preparing includes the salt (I), the catalyst (II), and the cross-linking agent It includes preparing an aqueous solution containing (III) while heating. And performing the cross-linking reaction includes drying the aqueous solution to generate a solid material and heat-treating the generated solid material to perform the cross-linking reaction. I'm in.

According to this configuration, a powdery superabsorbent resin can be obtained. The cross-linking reaction progresses to some extent even in the process of preparing an aqueous solution containing salt (I), catalyst (II), and cross-linking agent (III) while heating, It proceeds by applying

A third aspect of the present invention is a method for producing a superabsorbent polymer according to the first aspect, wherein the preparing includes the salt (I), the catalyst (II), and the cross-linking agent It includes preparing an aqueous solution containing (III) while heating. And causing the cross-linking reaction to occur includes mixing the aqueous solution with heated paraffin, and subjecting the mixed aqueous solution to a heat treatment to cause the cross-linking reaction. there is Furthermore, the method for producing the superabsorbent polymer further includes removing the paraffin at room temperature after the cross-linking reaction.

According to this configuration, a spherical superabsorbent resin can be obtained. The cross-linking reaction proceeds to some extent even in the process of preparing the aqueous solution containing the salt (I), the catalyst (II) and the cross-linking agent (III) while heating. It progresses by heat-treating the aqueous solution.

A fourth aspect of the present invention is a method for producing a superabsorbent polymer according to the first aspect, wherein the preparing includes the salt (I), the catalyst (II), and the cross-linking agent It includes preparing an aqueous solution containing (III) while heating. And performing the cross-linking reaction includes coating the aqueous solution on a coating substrate and subjecting the coated aqueous solution to heat treatment to perform the cross-linking reaction. there is

According to this configuration, a sheet-like or film-like superabsorbent resin can be obtained. The cross-linking reaction proceeds to some extent even in the process of preparing an aqueous solution containing salt (I), catalyst (II), and cross-linking agent (III) while heating. It progresses by heat-treating the aqueous solution.

A fifth aspect of the present invention is a method for producing a superabsorbent resin according to any one of the first to fourth aspects, wherein the catalyst (II) is an acidic catalyst such as formic acid, methanesulfone At least one selected from acids, p-toluenesulfonic acid, phosphoric acid, and dodecylbenzenesulfonic acid, or basic catalysts 1H-imidazole, 2-methylimidazole, 2-undecylimidazole, 2 -heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undeciberimidazole, 1-cyanoethyl-2 -ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, N,N'methylbenzylamine, picoline, and at least one selected from pyridine.

According to this configuration, a catalyst having excellent catalytic properties is used for the cross-linking reaction. A water absorbent resin is obtained.

A sixth aspect of the present invention is a method for producing a superabsorbent resin according to any one of the first to fifth aspects, wherein the functional group is selected from a hydroxyl group, an epoxy group, and an amino group. At least one selected.

According to this configuration, a polyfunctional compound having excellent properties is used as a cross-linking agent, so that the cross-linking reaction proceeds smoothly.

As described above, according to the present invention, a superabsorbent resin can be obtained in which the superabsorbent property is stable over a long period of time by a crosslinking reaction at a lower temperature and/or in a shorter time. method is realized.

As described above, the method for producing a superabsorbent resin according to the present invention is as follows.
(a) a salt (I) of a copolymer of isobutylene and maleic anhydride and an alkaline substance, a catalyst (II) for a cross-linking reaction, and a cross-linking agent (III) which is a polyfunctional compound having two or more functional groups ), and (b) performing a cross-linking reaction to cross-link the salt (I) with the cross-linking agent (III) in the presence of the catalyst (II). .

Preferred forms of each material and preferred forms of manufacturing processes are illustrated below.
As for preferable examples of the salt (I) and the cross-linking agent (III), the knowledge described in Patent Document 1 can be used as it is, as exemplified below.
First, the molecular weight of the copolymer (particularly alternating copolymer) of isobutylene and maleic anhydride is such that the value of the intrinsic viscosity [η] measured at 30°C in a dimethylformamide solution is 0.1 to 8 (dl/g ), particularly preferably in the range of 0.2 to 5 (dl/g). When a resin with a limiting viscosity of less than 0.1 is used, it is difficult to obtain a resin having a large water absorption capacity, and the durability of the superabsorbent resin may be lowered. On the other hand, if the intrinsic viscosity is higher than 8, the viscosity of the solution becomes high when it is made into an aqueous solution, which may cause production problems.

Examples of alkaline substances include sodium hydroxide, potassium hydroxide, calcium hydroxide, lithium hydroxide, magnesium hydroxide, ammonium hydroxide, ammonia gas, methylamine, ethylamine, propylamine, dimethylamine, diethylamine, triethylamine, and monoethanol. amine, diethanolamine, sodium carbonate, potassium carbonate, sodium acetate, potassium acetate, ammonium acetate, disodium phosphate, trisodium phosphate and the like. Among these, sodium hydroxide, potassium hydroxide and ammonia are preferred, and two or more of these alkaline substances may be used in combination.

The ratio of reaction of the alkaline substance to the alternating copolymer of isobutylene and maleic anhydride, that is, the ratio of neutralization (hereinafter referred to as the "degree of neutralization") is important. Assuming that the degree of neutralization (α) is 100%, the degree of neutralization (α) is desired to be in the range of 10 to 90%. If the degree of neutralization (α) is lower than 10%, sufficient water absorption performance may not be obtained. Moreover, when the degree of neutralization (α) is higher than 90%, the gel strength in the swollen state may decrease. A particularly preferred range is 30-70%. The presumed pH is almost determined by the degree of neutralization, but it can be slightly adjusted depending on the selection and amount of the desired catalysts, that is, the acid catalyst and the basic catalyst. If the degree of neutralization is approximately neutral, either of the two may be used. If the degree of neutralization is small, an acid catalyst can be selected, and if it is large, a basic catalyst can be selected.

The cross-linking agent (III) is preferably used in a proportion of 0.01 to 5% by weight, more preferably 0.1 to 2% by weight, relative to the salt of (I).

The cross-linking agent (III) that can be used is a polyfunctional compound having two or more functional groups such as a hydroxyl group, an epoxy group and an amino group. Diethylene glycol, polyethylene glycol, polypropylene glycol, polyglycerin, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, polyvalent amine group polyethyleneimine, ethanolamine, ethylenediamine, propylenediamine, trimethylolmelamine, pentaerythritol, urea, triethylenediamine, triethylenetetramine, hexamethylenetetramine, diethylenetriamine, triethyltetramine, tetraethylenepentamine, pentaethylenehexamine, and the like. These crosslinking agents preferably have a molecular weight of 60 to 100,000, more preferably 60 to 5,000. You may use it in combination of 2 or more types.

The catalyst (II) for the cross-linking reaction is preferably formic acid, toluenesulfonic acid as an acidic catalyst, and imidazole group, pyridine, picoline, N,N'methylbenzylamine as a basic catalyst. The amount of the catalyst may be adjusted as appropriate, but basically it is used at a rate of 0.01 to 5% by weight, more preferably 0.1 to 3% by weight, depending on the amount of the cross-linking agent.

In prior art production processes without catalysts, it takes a long time to reach the desired target level of cross-linking, and even after reaching the target level, the reaction still proceeds. Therefore, the high water absorption property is not stable forever. In contrast, in the manufacturing method of the embodiment of the present invention, the cross-linking reaction is carried out in the presence of a catalyst, so the cross-linking reaction reaches the target level in a shorter time when compared at the same heat treatment temperature. Moreover, the reaction hardly progresses after the target level is reached.

Regarding the processing temperature during the manufacturing process, in the initial solution state, 80 ° C. to 95 ° C. is maintained during neutralization, 40 ° C. to 60 ° C. is maintained when adding a cross-linking agent and catalyst, and 110 ° C. in the pulverization method. 95° C. in paraffin in the spheronizing method, and at about 50° C. in the sheet coating method. The target temperature for the final heat treatment is about 160° C. to about 190° C. when no catalyst is added, and about 130° C. to about 150° C. when a catalyst is added.

As described above, in the production method of the embodiment of the present invention, when compared at the same heat treatment temperature, a superabsorbent resin having desirable high water absorbency is obtained by a short-time crosslinking reaction as compared with the conventional production method. Moreover, the superabsorbent property of the resulting superabsorbent resin is stable over a longer period of time. In addition, when compared with the same heat treatment time, in the production method according to the embodiment of the present invention, a superabsorbent resin having desirable high water absorption is obtained by a cross-linking reaction at a lower temperature than in the conventional production method. Moreover, the superabsorbent property of the resulting superabsorbent resin is stable over a longer period of time. The excellent effect of the manufacturing method according to the embodiment of the present invention is supported by the examples described below.
As an interesting discovery through the following examples, when a catalyst is added to an aqueous solution of a salt to which an alkaline substance is added and a cross-linking agent is added, and the mixture is heated at 60°C to 95°C, even in the aqueous solution It was found that a cross-linking reaction was initiated.

As examples of manufacturing processes, methods known as "powdering methods" and "spheronizing methods" can be employed. A method that should be called a "sheet coating method" can also be employed. In the following, examples will be described in which superabsorbent resins were experimentally produced by embodying the production method of the present invention by these methods.

[Example 1. (pulverization method)]
As Example 1, a high water-absorbing resin was experimentally produced using a powdering method as follows.
Isobutylene-maleic anhydride copolymer (intrinsic viscosity (η) at 30°C in dimethylformamide solution = 1.01, molar ratio of isobutylene: maleic anhydride = 1:1 in the copolymer) 100 parts by weight of "Isoban 10" manufactured by Kuraray Co., Ltd.), 31 parts by weight of sodium hydroxide, and 305 parts by weight of water are mixed, heated from room temperature to 95° C., and stirred to obtain isobutylene maleic anhydride copolymer. A homogeneous aqueous solution of sodium neutralization was prepared. The degree of neutralization α was 0.6.

Next, 0.5 parts by weight of polyethyleneimine having a molecular weight of 300 and 0.5 g of 1H-imidazole as a catalyst were added to 436 parts by weight of the above aqueous solution, and mixed well. Films were prepared by casting into resin-coated vats.
Next, after drying at 95° C. for 1 hour, it was heated at 120° C. for 1 hour, and further heat-treated at 150° C. for 2 hours. The reason why drying was performed at 100° C. or less is to remove air while suppressing boiling of water. A 20-mesh pass water-absorbing resin powder was obtained by pulverizing the plate-like material obtained by the heat treatment.

The product thus obtained was filtered through a 20-mesh cloth, hand-squeezed, the water absorption capacity was measured, and a durability test was conducted. The test results are shown in Table 1 together with comparative examples to be compared.

In a comparative example, an aqueous solution was prepared without adding a catalyst in the steps of Example 1, and then the same steps were performed to obtain a water absorbent resin powder. However, the temperature and time of the final heat treatment were 150° C.×2 hours, 165° C.×2 hours, and 180° C.×2 hours. These are referred to as Comparative Examples 1-1, 1-2, and 1-3, respectively.

The test method is as follows.
Before the durability test, 1 gram of the sample was weighed out with a balance, placed in a beaker containing 350 ml (milliliter) of purified water, left at room temperature for 2 hours, and then 200 mesh. After removing the free water by filtering with a nylon cloth and then squeezing lightly, the swollen specimen was weighed to measure how many times it had swelled.
In the durability test A, 350 g of water was added to 1 g of the water-absorbing resin, the mixture was sealed so as not to evaporate, and left at 25° C. for one year, and then the state of the hydrous gel was observed. In addition, water absorption capacity was also measured.
In the durability test B, 350 g of water was added to 1 g of the water-absorbing resin, the mixture was sealed so as not to evaporate the water, and the mixture was heated at 70° C. for 30 days, and then the state of the hydrous gel was observed. In addition, water absorption capacity was also measured.
In the durability test C, 350 g of water was added to 1 g of the water-absorbing resin, the mixture was sealed so as not to evaporate the water, and the mixture was heated at 100° C. for 48 hours, and then the state of the hydrous gel was observed. In addition, water absorption capacity was also measured.
In the heat resistance test D, the water absorbent resin was heated at 150° C. for 8 hours, and then the state of the hydrous gel was observed. In addition, water absorption capacity was also measured.
In the heat resistance test E, the water-absorbent resin was heated at 190° C. for 4 hours, and then the state of the water-containing gel was observed. In addition, water absorption capacity was also measured.
In durability tests A, B, C, D, and E, the absorption capacity test after the durability test by standing or heating was performed by lightly squeezing the sample placed in a wet state with a 200-mesh nylon cloth. After removing the free water, the swollen specimen was weighed to determine how many times the specimen swelled.

In the examples in which the catalyst was added, the initial water absorption capacity was stable until later, and heat treatment at 150°C for 2 hours was sufficient to obtain sufficient performance. On the other hand, in Comparative Examples 1-1, 1-2, and 1-3, the cross-linking was not sufficient, and therefore the water absorption capacity was not stabilized unless a sufficient heat treatment was performed. Countermeasures are taken by increasing the heat treatment temperature above 190° C. or extending the heat treatment time, but this causes the sample to turn yellow and become resinous, resulting in partial deterioration. By comparing the examples and comparative examples, it is understood that a stable water absorbent resin can be obtained by adding a catalyst.

[Example 2. (Spheroidizing method)]
Patent Document 3 describes the following manufacturing method as “Example 1”.
100 parts of an isobutylene maleic anhydride copolymer (“Isoban 10” manufactured by Kuraray Co., Ltd.) was added to 233 parts of an aqueous caustic soda solution having a concentration of 14%, and the mixture was heated and stirred to prepare a uniform aqueous solution having a degree of neutralization of 0.1. Next, to the prepared aqueous solution, 0.3 parts of polyethyleneimine having a molecular weight of 300 ("Epomin SP-003" manufactured by Nippon Shokubai Chemical Industry Co., Ltd.) was added as a cross-linking agent and mixed well. 1 part of oil-soluble surfactant ("Rhedol SP-030" manufactured by Kao Soap Co., Ltd.) of 1.8 is added to 333 parts of liquid paraffin dissolved therein, and the temperature is maintained at 95° C. for 25 hours while stirring to sufficiently remove water. Evaporated. Then, after solid-liquid separation, the product was washed with hexane and dried to obtain a spherical superabsorbent resin having a particle size of 32 to 100 mesh and a water absorption capacity of 350 times.

As Example 2 of the present invention, in the above method of Patent Document 3, when adding 0.3 part of polyethyleneimine SP-003, 0.3 g of 1H-imidazole as a catalyst was added, and the temperature was raised to 95 ° C. while suppressing the stirring speed. Keep for 5 hours to fully evaporate the water, then wash with hexane after solid-liquid separation, and dry to obtain a spherical object with a diameter of 0.5 mm to 2 mm, and further heat treatment at 150 ° C. for 2 hours. Thus, a spherical superabsorbent polymer was obtained. This water-absorbent resin is a spherical gel that has a water absorption capacity of about 220 times that of distilled water, and has a sustained release effect. In addition, it has excellent long-term stability, and when it is hydrated with distilled water, it withstands a durability test at 70 ° C for 30 days, and even after a durability test at room temperature for one year, it has 200 times more water absorption. was holding.

On the other hand, as Comparative Example 2, in the reaction system in which no catalyst was added, no water absorption was observed after one year. The manufacturing method of Comparative Example 2 is the same as the manufacturing method of Example 2, except that no catalyst was added. Table 2 shows the comparison results between Example 2 and Comparative Example 2.

In addition, in each of the methods of Example 2 and Comparative Example 2, it was confirmed whether or not a large-particle superabsorbent resin could be produced by slowing down the heating rate while stirring the sample put into the paraffin. . As a result, as shown in Table 2, the method of Example 2 yielded products with a diameter of 2 mm to 15 mm.

[Example 3. (Sheet coating method)]
As Example 3, a superabsorbent resin was experimentally produced by the following method.
100 parts by weight of isobutylene-maleic anhydride copolymer (60 parts by weight of Isoban 10 (weight average molecular weight: about 165,000) and 40 parts by weight of Isoban 06 (weight average molecular weight: about 85,000), totaling 100 parts by weight) , 31 parts by weight of sodium hydroxide, and 305 parts by weight of water are mixed, heated from normal temperature to 95° C., and stirred to prepare a uniform aqueous solution of sodium-neutralized isobutylene-maleic anhydride copolymer. did. Next, this aqueous solution is heated to 50° C., and 0.5 parts by weight of polyethylene having a molecular weight of 600 and 0.5 g of 2-methylimidazole as a catalyst are added to 436 parts by weight of the aqueous solution and mixed to obtain a coating solution. rice field. The coating liquid has a solid content of 30% and a slightly high viscosity at 30° C., so that it is ready for coating.

A PE/PP nonwoven fabric was laid on the prepared release paper, and a stainless steel punching plate (perforated plate with holes of 5 mm in diameter) was placed thereon and coated using a bar coater. This was used as a surface-coated sheet, and the sample was placed in an oven at 30°C with the gel-coated nonwoven fabric placed on the release paper, and the temperature was increased, and finally heat treatment was performed at 145°C for 30 minutes. A sheet was obtained (Example 3-1).

Furthermore, in order to prevent the gel from falling off after soaking with water, the nonwoven fabric was changed to rayon/polyester, and after coating, a sandwich structure was formed with the nonwoven fabric. The sample was placed in an oven at 30° C. while placed on the nonwoven fabric gel-coated on the release paper, the temperature was increased, and finally heat treatment was performed at 145° C. for 30 minutes to obtain a composite sheet (Example 3-2).

As a comparative example, a surface-coated sheet was obtained through the same steps as in Example 3-1 without adding the catalyst 2-methylimidazole (Comparative Example 3-1). Heat treatment causes deterioration, breakage, brittleness, and yellowing of not only the gel but also the adherend.
Table 3 shows the test results of these prototypes.

The following advantages could be confirmed by using the catalyst.
(1) The width of the molecular weight distribution can be widened. Thereby, the range of coating conditions can be widened.
(2) The concentration of the coating liquid can be increased. Thereby, the range of coating conditions can be widened.
(3) It is possible to greatly widen the selection range of the types of materials for the coated sheet, and to prevent deterioration of the heat resistance in particular.
(4) Reduction in heat treatment temperature and time can be expected. Thereby, an energy saving effect is obtained.
(5) Information on the viscosity and pH of the coating liquid is easy to understand. For this reason, on-site support is easy.

[Example 4. ]
Experiments were conducted to investigate how various factors related to the method of producing a superabsorbent polymer affect the properties of the produced superabsorbent polymer. The method of evaluation was based on the formulations of Example 1 and Comparative Example 1, which were lightened, heated, and stirred. °C x 2 hours. The results are shown in Table 4.
What is characteristic in Table 4 is that the mixed liquid, that is, the powdery isobutylene maleic anhydride is stirred in water while raising the temperature, and then an alkaline substance is added, neutralized, dissolved in water, and crosslinked. During the process of adding the cross-linking agent, the solution viscosity was measured after 1 hour at 50°C, and after the addition of the catalyst, the solution viscosity was measured. It can be seen that the viscosity increased due to heating inside. That is, the inventors discovered that crosslinking begins in an aqueous solution.
As shown in Table 4, it was found that the presence of the catalyst broadens the range of molecular weights of isobutylene maleic anhydride and slightly lowers the pH. Moreover, it was found that the heat treatment conditions were lowered, and the productivity was also improved. In addition, it is expected that various processing methods will become possible, that various forms will be considered, and that the range of applications will expand.

The following points were noted in the experiment.
(1) Use of an isobutylene-maleic anhydride copolymer. Furthermore, in order to obtain the optimum water absorbent resin, the molecular weight must have an optimum range.
(2) Use a water-soluble neutralizing agent to start the cross-linking reaction in water, and determine the degree of neutralization α according to the amount of the alkaline substance. An appropriate amount of alkaline substance should be present.
(3) A water-soluble cross-linking agent should be selected, and an appropriate amount should be added to the alkaline neutralized solution of isobutylene-maleic anhydride and thoroughly stirred and mixed.
(4) A liquid catalyst should be selected over a solid catalyst, and an acidic catalyst or a basic catalyst should be appropriately selected depending on the degree of neutralization. Either is acceptable in the neutral region.
(5) The criteria for cross-linking reaction should be confirmed by the viscosity of the solution, and the end point of the reaction should be selected according to the shape and performance of the finally obtained water absorbent resin.

Regarding the approximate performance of the water-absorbing resin, when measuring the water absorption capacity of the water-absorbing gel in a water-absorbing state, it is filtered with a 200-mesh cloth and squeezed. At that time, it is possible to make a rough guess based on the presence or absence of sliminess and hardness of the water (free water) coming out of the cloth. "Firmly", "slimy", and "presence or absence of slippery feeling" seemed to be easy-to-understand expressions. Good or bad productivity was indicated by symbols such as "double circle", "circle", "triangle", etc. ) was judged to be a “double circle”. It is understood that the performance of the obtained product is more stable when the catalyst is used.

Claims (6)

A salt (I) of a copolymer of isobutylene and maleic anhydride and an alkaline substance (I), a catalyst (II) for a crosslinking reaction, and a crosslinker (III) which is a polyfunctional compound having two or more functional groups, and
Carrying out a cross-linking reaction of cross-linking the salt (I) with the cross-linking agent (III) in the presence of the catalyst (II);
A method for producing a superabsorbent resin, comprising: The preparing includes preparing an aqueous solution containing the salt (I), the catalyst (II), and the cross-linking agent (III) while heating,
Carrying out the cross-linking reaction is
drying the aqueous solution to produce a solid;
performing the cross-linking reaction by subjecting the generated solid to a heat treatment;
The method for producing a super absorbent resin according to claim 1, comprising. The preparing includes preparing an aqueous solution containing the salt (I), the catalyst (II), and the cross-linking agent (III) while heating,
Carrying out the cross-linking reaction is
mixing the aqueous solution with warm paraffin;
and performing the cross-linking reaction by subjecting the mixed aqueous solution to a heat treatment,
The method for producing the superabsorbent resin comprises
2. The method for producing a superabsorbent polymer according to claim 1, further comprising removing the paraffin at room temperature after the cross-linking reaction. The preparing includes preparing an aqueous solution containing the salt (I), the catalyst (II), and the cross-linking agent (III) while heating,
Carrying out the cross-linking reaction is
applying the aqueous solution to a coating substrate;
performing the cross-linking reaction by subjecting the applied aqueous solution to a heat treatment;
The method for producing a super absorbent resin according to claim 1, comprising. The catalyst (II) is
At least one acid catalyst selected from formic acid, methanesulfonic acid, p-toluenesulfonic acid, phosphoric acid, and dodecylbenzenesulfonic acid, or
Basic catalysts 1H-imidazole, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 1- cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undeciberimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, N,N'methylbenzylamine, picoline, and at least one selected from pyridines,
5. The method for producing a super absorbent resin according to any one of claims 1 to 4. 6. The method for producing a superabsorbent resin according to any one of claims 1 to 5, wherein said functional group is at least one selected from a hydroxyl group, an epoxy group and an amino group.