KR20110111938A - Method for preparation of water absorbent resin - Google Patents

Abstract

The present invention relates to a method for preparing an absorbent resin. According to the present invention, a method for solving a high drying time, which is a problem of an existing absorbent resin, by treating particles with a basic material for neutralization and then drying the drying time It can shorten the time can be provided a manufacturing method of the absorbent resin suitable for mass production.
According to an embodiment of the present invention, (a) internally cross-linking the acrylic acid monomer aqueous solution with a first crosslinking agent to produce a gel resin; (b) subdividing the gel resin to produce a granulated gel resin; (c) drying, pulverizing and classifying the granular gel-type resin to produce a resin powder; And (d) surface crosslinking the resin powder with a second crosslinking agent to produce an absorbent resin, wherein the granular gel resin is neutralized with an alkaline aqueous solution between steps (b) and (c). step; neutralizing the resin powder with an aqueous alkaline solution between steps (c) and (d); And (d) neutralizing the absorbent resin with an alkaline aqueous solution after step (d).

Description

Method for preparation of water absorbent resin

The present invention relates to a method for preparing an absorbent resin suitable for mass production by making the particle size fine and treating with a basic material for neutralization and drying to shorten the drying time and to obtain a uniformly neutralized product.

Absorption mechanism of the absorbent resin is due to the interaction between the penetration pressure due to the difference in electrical attraction force of the charge of the polymer electrolyte, the affinity between water and the polymer electrolyte, the expansion of the molecule due to the repulsive force between the polymer electrolyte ions, and the expansion inhibition due to crosslinking. Is dominated. That is, the absorbent capacity of the absorbent polymer depends on the affinity and molecular expansion described above, and the rate of absorption depends largely on the penetration pressure of the absorbent polymer itself. Thus, the molecular expansion and penetration pressure of the absorbent polymer chains depend on the crosslinking density and distribution introduced or the type of crosslinking agent.

Conventional techniques for improving the absorption rate have been mainly used to increase the surface area of the absorbent resin, to reduce the particle size, to prepare a granular form, or to use the blowing agent to form micropores in and outside the resin.

U.S. Patent Publication (US6565768) provides a process for preparing an absorbent polymer comprising adding hydrogel and neutralizer to a mincer and neutralizing to produce partially neutralized and granular hydrogel particles at 60 to 85 mole percent.

European patent (EP-A-0205674) provides a process for the preparation of absorbent resins in which acidic polymers are prepared at 0 to 100 ° C. and the acidity (pH) is determined in accordance with the partial neutralization of the hydrogel.

The present invention is to solve the problem of non-uniformity and long drying, which is a problem of the conventional production method of absorbent resin by making a fine particle size in order to solve the problems with the absorbent resin manufacturing method and then neutralizing the basic material for neutralization. It is possible to obtain a product of uniform quality and to shorten the drying time, and to provide a method for preparing an absorbent resin suitable for mass production.

According to the invention, (a) the step of internally crosslinking the aqueous acrylic acid monomer solution with a first crosslinking agent to produce a gel resin; (b) subdividing the gel resin to produce a granulated gel resin; (c) drying, pulverizing and classifying the granular gel-type resin to produce a resin powder; And (d) surface crosslinking the resin powder with a second crosslinking agent to produce an absorbent resin, wherein the granular gel resin is neutralized with an alkaline aqueous solution between steps (b) and (c). step; neutralizing the resin powder with an aqueous alkaline solution between steps (c) and (d); And (d) neutralizing the absorbent resin with an alkaline aqueous solution after step (d).

According to a preferred embodiment of the present invention, the acrylic acid monomer of the present invention can be provided a method for producing an absorbent resin, characterized in that the compound represented by the formula (1).

[Formula 1]

R ¹ -COOM ¹

In Formula 1, R ¹ is an alkyl group having 2 to 5 carbon atoms including an unsaturated bond, and M ¹ is a hydrogen atom, a monovalent or divalent metal, an ammonium group, or an organic amine salt.

According to another preferred embodiment of the present invention, the acrylic acid monomer content in the acrylic acid monomer solution may be provided with a method for producing an absorbent resin, characterized in that 40 to 95 parts by weight based on 100 parts by weight of the total amount of the acrylic acid monomer solution. .

According to another preferred embodiment of the present invention, the first crosslinking agent is N, N'-methylenebisacrylamide, trimethylolpropane tri (meth) acrylate, ethylene glycol di (meth) acrylate, polyethylene glycol (meth) acrylic Latex, propylene glycol di (meth) acrylate, polypropylene glycol (meth) acrylate, butanediol di (meth) acrylate, butylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, Hexanediol di (meth) acrylate, triethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, dipentaerythritol pentaacrylate, glycerin tri ( Meth) acrylate, pentaerythritol tetraacrylate, triarylamine, ethylene glycol diglycidyl ether , Propylene glycol, glycerin, and ethylene carbonate can be provided a method for producing an absorbent resin, characterized in that at least one member selected from the group consisting of.

According to another preferred embodiment of the present invention, a method for producing an absorbent resin, characterized in that the crosslinking temperature of step (a) is 20 to 75 ℃.

According to another preferred embodiment of the present invention, the second crosslinking agent is ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol polyglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol di Glycidyl ether, ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, tetraethylene glycol, propane diol, dipropylene glycol, polypropylene glycol, glycerin, polyglycerine, butanediol, heptanediol, hexanedi Absorbent resin, characterized in that at least one selected from the group consisting of all trimethylolpropane, pentaerythritol, sorbitol, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, iron hydroxide, calcium chloride, magnesium chloride, aluminum chloride, or iron chloride The manufacturing method of may be provided.

In addition, the cross-linking temperature of step (d) may be provided a method for producing an absorbent resin, characterized in that 90 to 250 ℃.

According to another preferred embodiment of the present invention, the alkaline aqueous solution is at least one aqueous solution selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonium carbonate, sodium carbonate, potassium carbonate, ammonium phosphate and sodium phosphate A method for producing an absorbent resin can be provided.

As described above, the present invention treats the basic material for neutralization after making the particle size fine and dried, thereby solving the long drying time of the existing water-absorbent resin manufacturing method and shortening the drying time to prepare an aqueous resin suitable for mass production. It may provide a method.

1 is a view schematically showing a manufacturing process of an absorbent resin according to an embodiment of the present invention.

Hereinafter, a preferred embodiment of the method of manufacturing an absorbent resin according to the present invention will be described in detail with reference to the accompanying drawings, in which the same or corresponding components are given the same reference numerals and are duplicated thereto. The description will be omitted.

1 is a view schematically showing a process diagram for a method of manufacturing an absorbent resin according to an embodiment of the present invention.

Referring to Figure 1, the method for producing an absorbent resin according to an embodiment of the present invention (S110) is a step of producing a gel resin by internally cross-linking the acrylic acid-based monomer aqueous solution with a first crosslinking agent (S110);

Subdividing the gel-type resin to generate a subdivided gel-type resin (S120);

Drying, pulverizing and classifying the granular gel-type resin to generate a resin powder (S130); And

In the method for producing an absorbent resin comprising the step of surface crosslinking the resin powder with a second crosslinking agent (S140),

Neutralizing the gel-type resin subdivided between steps S120 and S130 with an alkaline aqueous solution (S121); Neutralizing the resin powder with an alkaline aqueous solution between steps S130 and S140 (S131); And neutralizing the absorbent resin with the alkaline aqueous solution after the step S140 (S141).

Referring to FIG. 1, the method for preparing an absorbent resin first includes internally crosslinking an acrylic acid monomer solution with a first crosslinking agent to generate a gel resin (S110).

Acrylic acid monomer

An acrylic acid monomer which is a compound represented by the following Chemical Formula 1 may be used in the method for preparing an absorbent resin of the present invention.

[Formula 1]

R ¹ -COOM ¹

In Formula 1, R ¹ is an alkyl group having 2 to 5 carbon atoms including an unsaturated bond, and M ¹ is a hydrogen atom, a monovalent or divalent metal, an ammonium group, or an organic amine salt.

More preferably, acrylic acid or methacrylic acid may be used alone or in combination of two or more thereof in the method for producing the absorbent resin of the present invention.

The acrylic acid monomer content in the aqueous acrylic acid monomer solution is preferably 40 to 95 parts by weight based on 100 parts by weight of the total content of the acrylic acid monomer solution.

This is to avoid the need to remove the unreacted monomer after polymerization by using the gel effect phenomenon that occurs in the polymerization reaction of a high concentration aqueous solution.

Initiator

Examples of the polymerization initiator include radical polymerization initiators such as potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide, t-butylhydroperoxide, and hydrochloride salts of 2,2'-azobis-2-amidinopropane and 2-hydroxy- Photoinitiator of 2-methyl-1-phenyl-propan-1-one can be used. These and the reducing agent which accelerates | decomposes the decomposition of a polymerization initiator can be used together, and it can also be set as a redox-type initiator by combining both. As the reducing agent, sulfites such as sodium sulfite and sodium hydrogen sulfite, reducing metals such as ferrous salts, L-ascorbic acid and amines may be used alone or in combination of two or more, but are not limited thereto.

The concentration of the initiator is preferably 0.001 to 1.0 mol parts based on 100 mol parts of the total monomers. The initiator may be used together with a redox catalyst, and it is more preferable to use L-ascorbic acid.

First Bridge

The use of a crosslinking agent in the preparation of the absorbent polymer is necessary to maintain the physical properties of the resulting absorbent polymer. As a crosslinking method of the water absorbent resin, there are a simultaneous crosslinking method capable of introducing crosslinking between chains of the absorbent polymer during polymerization, and a postcrosslinking method of causing crosslinking of functional groups of the absorbent polymer after polymerization.

In this case, in order to reduce the decrease in absorbance due to the increase in the crosslinking density, when using a crosslinking agent having a suitable chain length, it was possible to prepare a water absorbent resin having high absorbency while maintaining excellent gel strength.

As crosslinking agents which can be crosslinked as the first crosslinking agent, α, β-unsaturated carboxylic acid monomers and any compound monomer capable of introducing a crosslinking bond during polymerization may be used. For example, N, N'-methylenebisacrylamide, trimethylolpropane tri (meth) acrylate, ethylene glycol di (meth) acrylate, polyethylene glycol (meth) acrylate, propylene glycol di (meth) acrylate, Polypropylene glycol (meth) acrylate, butanediol di (meth) acrylate, butylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, hexanediol di (meth) acrylate, tri Ethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, dipentaerythritol pentaacrylate, glycerin tri (meth) acrylate, pentaerythritol tetraacrylate , Triarylamine, ethylene glycol diglycidyl ether, propylene glycol, glycerin, or ethylene carbo Sites for it is not may be used alone or in combination two, limited.

The content of the first crosslinking agent used is preferably 0.001 to 2.0 parts by weight based on 100 parts by weight of the acrylic acid monomer. If the content of the crosslinking agent is less than 0.001 part by weight, the absorption rate and the gel strength are too weak. If the content of the crosslinking agent is more than 2.0 parts by weight, the absorbency is too low, which is not preferable as the absorbent.

Referring to Figure 1, after the step of producing a gel-type resin (S110), the gel-type resin is subdivided to generate a granular gel-type resin (S120).

Crushers usable in the present invention for subdividing gel-type resins include shear granulation machines, impact crushers and high speed rotation crushers. Mills imparted with one or more grinders among cutting, shearing, impact and friction may be preferably used, in particular grinders with a cutting or shearing device imparted as a primary function, more preferably The grinder can be used where shearing and cutting effects are expected to be strong. Among the other pulverizers listed above, an apparatus having a grinding effect required by the shear formed by the plurality of rotary blades and the fixed blade is particularly preferred.

The rotational speed of the rotary blade is preferably 3.0 to 200 m / sec, more preferably 5.0 to 150 m / sec.

Drying, pulverizing and classifying the granular gel-type resin to produce a resin powder (S130) is included in the method of preparing the absorbent resin of the present invention.

In the present invention, the granular gel resin is dried in a range of 50 to 250 ° C, more preferably in a range of 100 to 180 ° C. If the drying temperature is less than 100 ° C., this shortage only increases the time required for drying and reduces productivity.

Drying can take place using ordinary drying equipment or heating furnaces. As a typical example of the apparatus usable for such heat treatment, a grooved type mixing drier, a rotary drier, a disc drier, a fluidized bed drier, an airflow drier, or an infrared drier can be used.

Referring to Figure 1, the manufacturing method of the absorbent resin of the present invention includes the step of cross-linking the resin powder with a second crosslinking agent to generate an absorbent resin (S140).

Second cross-link

The second crosslinking agent is, for example, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol polyglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, or the like. Epoxy compounds, ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, tetraethylene glycol, propane diol, dipropylene glycol, polypropylene glycol, glycerin, polyglycerol, butanediol, heptanediol, hexanediol trimethyl Polyhydric alcohol compounds such as roll propane, pentaerythritol, or sorbitol, or polyhydric metal compounds such as hydroxides or chlorides such as calcium, magnesium, aluminum, or iron may be used alone or in combination of two or more thereof. no.

The content of the second crosslinking agent used is preferably 0.001 to 2.0 parts by weight based on 100 parts by weight of the dry neutralized resin powder.

The relative amount of the first crosslinking agent and the second crosslinking agent is determined according to the chain length and type of the crosslinking agent.

Temperature and time of crosslinking polymerization reaction

In the case of the first crosslinking reaction, the reaction temperature is preferably 20 to 75 ° C, and the polymerization reaction is completed within 1 minute to 4 hours.

In the case of the second crosslinking reaction, the reaction temperature is preferably 90 to 160 ° C, and the polymerization reaction is completed within 1 minute to 4 hours.

Referring to Figure 1, according to a preferred embodiment of the present invention, the step of granulating the gel-type resin to produce a granular gel-type resin (S120) and the step of drying, grinding and classifying the granular gel-type resin to generate a resin powder ( Neutralizing the gel-type resin subdivided between S130) with an alkaline aqueous solution (S121); Neutralizing the resin powder with an alkaline aqueous solution between S130 and the step of surface crosslinking the resin powder with a second crosslinking agent (S140) to produce an absorbent resin (S131); And neutralizing the water absorbent resin with an alkaline aqueous solution after the step S140 (S141) provides a method for producing an absorbent resin, characterized in that it comprises at least one step.

According to a preferred embodiment of the present invention, the granular gel-type resin is divided between the step of producing a granular gel-type resin (S120) and the granulated gel-type resin is dried, pulverized and classified to produce a resin powder (S130) It may include the step of neutralizing the alkaline aqueous solution (S121).

As a method of drying the neutralized resin powder, a method of drying the granulated gel resin can be used.

Alkaline aqueous solution

In the method for preparing the absorbent polymer of the present invention, the basic material which can be used to prepare the alkaline aqueous solution is not particularly limited. Preferably, sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonium carbonate, sodium carbonate, potassium carbonate, ammonium phosphate Alternatively, sodium phosphate may be used alone or in combination of two or more to make an aqueous solution, but is not limited thereto.

In the aqueous alkali solution, the acid groups of the acrylic acid monomers are neutralized in one or two stages with a limit of about 50 mol% or more. That is, the acid groups are preferably present as sodium, potassium, or ammonium salts. The final degree of neutralization is between 50 and 100 mol%.

According to a preferred embodiment of the present invention, between the step (S130) of producing a resin powder by drying, pulverizing and classifying the granular gel-type resin and the step of surface cross-linking the resin powder with a second crosslinking agent to produce an absorbent resin (140). Neutralizing the resin powder into the aqueous alkaline solution (S131) may be included.

According to a preferred embodiment of the present invention, after cross-linking the resin powder with the second crosslinking agent to generate an absorbent resin 140, the surface-crosslinked absorbent resin may be neutralized with an alkaline aqueous solution (S131).

[Example]

Preferred embodiments of the method for preparing the absorbent resin to be implemented in the present invention are described below, but the present invention is not limited thereto.

Example 1

To 500 g of acrylic acid was dissolved by adding 1.0 g of N, N'-methylenebisacrylamide as an internal crosslinking agent, and 555.1 g of 20% sodium hydroxide solution was added to prepare a water-soluble unsaturated monomer solution. The water-soluble unsaturated monomer aqueous solution was supplied to a 5 L capacity twin arm kneader having a sigma shaft, and nitrogen gas was added for 30 minutes while maintaining at 40 ° C. to remove oxygen dissolved in the aqueous solution. While stirring, 50.1 g of 0.2% by weight L-ascorbic acid, 50.5 g of aqueous sodium persulfate solution and 51.0 g of 2.0% by weight aqueous hydrogen peroxide solution were added. The polymerization was started after 20 seconds and the resulting gel was finely divided for 30 minutes using shear force.

The finely divided gel was spread about 30 mm thick on a stainless wire gauze having a pore size of 600 μm and dried in a 140 ° C. hot air oven for 5 hours. The dry polymer thus obtained was pulverized using a pulverizer, and classified into a standard mesh of ASTM specification to obtain an absorbent resin powder (1) having a particle size of 150 to 850 µm.

100 g of the obtained water absorbent resin powder (1) was mixed evenly by adding 0.3 g of ethylene glycol diglycidyl ether, 3.0 g of methanol, and 3.0 g of water, and surface-crosslinked. Thereafter, 136.1 g of 20% sodium hydroxide solution was added thereto, neutralized, and dried in a 140 ° C. hot air oven for 30 minutes. The dried powder was classified into a standard mesh of ASTM standard to obtain an absorbent resin powder (2) having a particle size of 150 to 850 μm.

Example 2

In the same manner as in Example 1, the absorbent resin powder 1 is obtained.

416.3 g of 50% aqueous sodium hydroxide solution was added to 100 g of the obtained absorbent polymer powder (1), neutralized, surface crosslinked, and dried in a hot air oven at 140 ° C. for 30 minutes. The dried powder was classified into a standard mesh of ASTM standard to obtain an absorbent resin powder (3) having a particle size of 150 to 850 µm.

Comparative Example 1

To 500 g of acrylic acid was dissolved by adding 1.0 g of N, N'-methylenebisacrylamide as an internal crosslinking agent, and 555.1 g of 20% sodium hydroxide solution was added to prepare a water-soluble unsaturated monomer solution. The water-soluble unsaturated monomer aqueous solution was supplied to a 5 L capacity twin arm kneader having a sigma shaft, and nitrogen gas was added for 30 minutes while maintaining at 40 ° C. to remove oxygen dissolved in the aqueous solution. While stirring, 50.1 g of 0.2% by weight L-ascorbic acid, 50.5 g of aqueous sodium persulfate solution and 51.0 g of 2.0% by weight aqueous hydrogen peroxide solution were added. The polymerization was started after 20 seconds and the resulting gel was finely divided for 30 minutes using shear force.

485.7 g of 20% sodium hydroxide solution was added to the finely divided gel and mixed for 10 minutes in the kneader, and then the gel was taken out, spread out about 30 mm thick on a stainless wire gauze having a pore size of 600 µm, and then in a 140 ° C hot air oven. Dry for 5 hours. The dry polymer thus obtained was pulverized using a pulverizer, and classified into a standard mesh of ASTM standard to obtain an absorbent resin powder (4) having a particle size of 150 to 850 µm.

100 g of the obtained water-absorbent resin powder (4) was mixed evenly with 0.3 g of ethylene glycol diglycidyl ether, 3.0 g of methanol, and 3.0 g of water, followed by drying in a 140 ° C. hot air oven for 30 minutes to perform surface crosslinking polymerization. The dried powder was classified into a standard mesh of ASTM standard to obtain an absorbent resin powder (5) having a particle size of 150 to 850 µm.

Claims (8)

(a) internally crosslinking the aqueous acrylic acid monomer solution with a first crosslinking agent to produce a gel resin;
(b) subdividing the gel resin to produce a granulated gel resin;
(c) drying, pulverizing and classifying the granular gel-type resin to produce a resin powder; And
(d) surface-crosslinking the resin powder with a second crosslinking agent to produce an absorbent resin;
neutralizing the granular gel-type resin with an aqueous alkaline solution between steps (b) and (c); neutralizing the resin powder with an aqueous alkaline solution between steps (c) and (d); And (d) neutralizing the absorbent resin with an aqueous alkaline solution after the step (d). The method of claim 1, wherein the acrylic acid monomer is represented by the following formula (1).
[Formula 1]
R ¹ -COOM ¹
In Formula 1, R ¹ is an alkyl group having 2 to 5 carbon atoms including an unsaturated bond, and M ¹ is a hydrogen atom, a monovalent or divalent metal, an ammonium group, or an organic amine salt. The method of claim 1, wherein the acrylic acid monomer content in the aqueous acrylic acid monomer solution is 40 to 95 parts by weight based on 100 parts by weight of the total content of the acrylic acid monomer solution. The method of claim 1, wherein the first crosslinking agent is N, N'-methylenebisacrylamide, trimethylolpropane tri (meth) acrylate, ethylene glycol di (meth) acrylate, polyethylene glycol (meth) acrylate, propylene glycol die (Meth) acrylate, polypropylene glycol (meth) acrylate, butanediol di (meth) acrylate, butylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, hexanedioldi ( Meta) acrylate, triethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, dipentaerythritol pentaacrylate, glycerin tri (meth) acrylate, Pentaerythritol tetraacrylate, triarylamine, ethylene glycol diglycidyl ether, propylene glycol, glycerin, And ethylene carbonate. The method for producing an absorbent resin, characterized in that at least one selected from the group consisting of The method of claim 1, wherein the crosslinking temperature of step (a) is 20 to 75 ℃. The method of claim 1, wherein the second crosslinking agent is ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol polyglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, Ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, tetra ethylene glycol, propane diol, dipropylene glycol, polypropylene glycol, glycerin, polyglycerol, butanediol, heptanediol, hexanediol trimethylolpropane, Pentaerythritol, sorbitol, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, iron hydroxide, calcium chloride, magnesium chloride, aluminum chloride, and a method for producing an absorbent resin, characterized in that at least one selected from the group consisting of iron chloride. The method of claim 1, wherein the crosslinking temperature of step (d) is 90 to 250 ℃. The method of claim 1, wherein the alkaline aqueous solution is at least one aqueous solution selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonium carbonate, sodium carbonate, potassium carbonate, ammonium phosphate and sodium phosphate. .

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