KR101350958B1 - Preparation Method for Water Absorbent Resin with High Productivity - Google Patents

Preparation Method for Water Absorbent Resin with High Productivity Download PDF

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KR101350958B1
KR101350958B1 KR1020090105910A KR20090105910A KR101350958B1 KR 101350958 B1 KR101350958 B1 KR 101350958B1 KR 1020090105910 A KR1020090105910 A KR 1020090105910A KR 20090105910 A KR20090105910 A KR 20090105910A KR 101350958 B1 KR101350958 B1 KR 101350958B1
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resin
absorbent resin
acrylate
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method
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KR1020090105910A
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KR20110049072A (en
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권종혁
원태영
조희정
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주식회사 엘지화학
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Abstract

The present invention relates to a method for preparing an absorbent resin, and specifically, (a) generating a gel resin by internally cross-linking an acrylic acid-based monomer aqueous solution containing an acidic group with a first crosslinking agent; Subdividing the gel resin to produce a fine gel resin (b); Drying and grinding the fine gel resin to produce a base resin powder (c); It provides a method of producing an absorbent resin comprising the step (e) of surface cross-linking the base resin powder with a polyhydric alcohol type second crosslinking agent at a relative humidity of 0.1 to 2% at a temperature of 100 to 170 ℃ (e). . According to the present invention, by lowering the relative humidity at the time of surface crosslinking, a method of lowering the high temperature surface crosslinking reaction temperature, which is a problem of the conventional manufacturing method of the absorbent resin, a large amount that can lower the production cost by lowering the surface crosslinking reaction temperature It is possible to provide a method for preparing an absorbent resin suitable for production.
Absorbent resin, relative humidity, surface crosslinking, acrylic acid monomer, crosslinking agent, polyhydric alcohol

Description

Preparation Method for Water Absorbent Resin with High Productivity

According to the present invention, the surface crosslinking reaction of the base resin powder at a low relative humidity enables the surface crosslinking reaction at a low temperature, thereby reducing the production cost and shortening the drying time, thereby resulting in high productivity and suitable properties for mass production. The present invention relates to a method for producing an improved absorbent resin.

Absorption mechanism of the absorbent resin is based on the interaction between the penetration pressure caused by 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 resin depends on the affinity and molecular expansion described above, and the rate of absorption greatly depends 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.

As the absorbent resin increases, the absorbent resin blocks the flow of the absorbed fluid due to adhesion between the absorbent resin particles swollen to the fluid. In order to improve this, there is a method of obtaining an absorbent resin having a hard particle surface by reacting the surface of the absorbent resin particle with a crosslinking agent. Such core-shell absorbent resins can be made to have an absorbent polymer having excellent absorbency and absorbency under pressure by increasing the permeability of the fluid as well as the absorbency under a certain load.

Japanese Laid-Open Patent Publication (JP 1999-279288) provides a method for producing an absorbent comprising adding and heating a vinyl compound and a polyhydric alcohol to an absorbent resin.

Japanese Laid-Open Patent Publication (JP 2007-144423) provides an absorbent which crosslinks the surface of the absorbent resin particles and ionically bonds with the cationic polymer compound.

Korean Unexamined Patent Publication (KR 2007-0094741) provides a method for treating a surface of an absorbent resin, comprising mixing the absorbent resin, the radical polymerization initiator, and the radical polymerizable compound, and irradiating active energy rays to the resulting mixture. .

Korean Patent Registration (KR 10-0340631) discloses polymerizing a water-absorbent resin in the presence of a water-soluble chain-transfer agent, treating the polymerized water-absorbent resin with a hydrophilic solution, and treating the treated water-absorbent resin. Provided is a method of preparing a water-absorbent comprising heating in the presence of a surface-crosslinking agent.

Since the crosslinking temperature at the time of surface crosslinking is required in the above-mentioned known technology, in the present invention, the preparation of an absorbent resin having improved physical properties to reduce the production cost and improve productivity by lowering the high temperature surface crosslinking temperature according to the present invention. Provide a method.

The present invention is to solve the problems of the conventional absorbent resin manufacturing method by lowering the relative humidity at the time of cross-linking, to solve the high production cost and low productivity of the conventional production method of absorbent resin to lower the production cost, productivity It is an object of the present invention to provide a method for preparing an absorbent resin having improved physical properties.

The present invention comprises the steps of internally cross-linking the acrylic acid monomer solution containing an acid group with a first crosslinking agent to generate a gel resin (a); Subdividing the gel resin to produce a fine gel resin (b); Drying and grinding the fine gel resin to produce a base resin powder (c); (E) surface-crosslinking the base resin powder with a polyhydric alcohol type second crosslinking agent at a relative humidity of 0.1 to 2% at a temperature of 100 to 170 ° C to produce an absorbent resin; It provides a method for producing an absorbent resin comprising a.

Here, the step (e) of generating the absorbent resin is characterized in that the base resin powder is cross-linked at a temperature of 150 to 160 ℃ to produce an absorbent resin.

According to the present invention, the acrylic acid monomer is characterized in that represented by the following formula (1).

[Formula 1]

R 1 -COOM 1

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

The acrylic acid monomer of the present invention is characterized by at least one member selected from the group consisting of acrylic acid, methacrylic acid, monovalent metal salts, divalent metal salts, ammonium salts and organic amine salts of these acids.

In the present invention, the aqueous acrylic acid monomer solution of step (a) may be 40 to 90 mol% neutralized acrylic acid monomer aqueous solution.

Further, the first crosslinking agent of the present invention is 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, hexanedioldi (meth) Acrylate, triethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, dipentaerythritol pentaacrylate, glycerin tri (meth) acrylate, pentaery Stall tetraacrylate, triarylamine, ethylene glycol diglycidyl ether, propylene glycol, glycerin, And it is characterized in that at least one member selected from the group consisting of ethylene carbonate.

The crosslinking temperature of step (a) of the present invention is characterized in that 20 to 120 ℃.

The average particle size of the microgel resin of the present invention is characterized in that 1 to 20mm.

The average particle size of the base resin powder of the present invention is characterized in that 100 to 850μm.

The second crosslinking agent of the present invention is ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, tetraethylene glycol, propane diol, dipropylene glycol, polypropylene glycol, glycerin, polyglycerine, butanediol, heptanediol, At least one member selected from the group consisting of hexanediol trimethylolpropane, pentaerythritol and sorbitol.

The average particle size of the absorbent resin of the present invention may be 150 to 850 μm.

The present invention provides an absorbent resin having an average particle size of 150 to 850 µm prepared according to the method for preparing the absorbent resin.

As described above, the present invention is a method of lowering the high temperature surface crosslinking reaction temperature, which is a problem of the existing method of manufacturing an absorbent resin, by lowering the relative humidity during surface crosslinking. And it can provide a method for producing an absorbent resin with improved physical properties that can improve the productivity.

Hereinafter, with reference to the accompanying drawings, a preferred embodiment of the method for producing an absorbent resin according to the present invention will be described in detail.

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 manufacturing method of the absorbent resin (S10) according to an embodiment of the present invention

Generating a gel-type resin by internal crosslinking of the aqueous acrylic acid monomer solution including an acidic group with a first crosslinking agent (S11);

Subdividing the gel resin to produce a fine gel resin (S12);

Drying and pulverizing the fine gel resin to produce a base resin powder (S13);

Surface-crosslinking the base resin powder with a polyhydric alcohol-type second crosslinking agent at a relative humidity of 0.1 to 2% at a temperature of 100 to 170 ° C. to produce an absorbent resin (S14);

It includes a method of producing an absorbent resin comprising a.

First, the method of preparing the absorbent resin (S10) includes a step (S11) of internally cross-linking an acrylic acid-based monomer aqueous solution containing an acid group with a first crosslinking agent (S11).

Acrylic acid monomer

Acrylic acid monomers, characterized in that represented by the following formula (1) can be used in the method for preparing the absorbent resin of the present invention.

[Formula 1]

R 1 -COOM 1

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

More preferably, acrylic acid, methacrylic acid, monovalent metal salts, divalent metal salts, ammonium salts or organic amine salts of these acids can be used alone or in combination of two or more as the acrylic acid monomer.

The acrylic acid monomer used in the present invention is used by partially neutralizing with an alkali such as sodium hydroxide, potassium hydroxide, ammonium hydroxide and the like. As alkali, sodium hydroxide which is inexpensive and nontoxic is more preferable.

As for the degree of neutralization of an acrylic acid monomer, 40-90 mol% is preferable. In particular, the range of the degree of neutralization varies depending on the final physical properties, but if it exceeds 90 mol%, it is difficult to control the reaction due to salt formation, etc. in the monomer solution. It exhibits the same properties as difficult elastic rubber.

The acrylic acid monomer content in the acrylic acid monomer aqueous solution is preferably 40 to 95 parts by weight based on 100 parts by weight of the total acrylic acid monomer aqueous 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. The amount of water, which is a solvent, is preferably used in a weight ratio of 1 to 5 times the content of acrylate, which is a monomer, and the amount of solvent is determined in consideration of the heat of polymerization.

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 mole parts of the initiator with respect to 100 mole 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 resin is necessary to maintain the physical properties of the resulting absorbent resin. The crosslinking method of the water absorbent resin includes a co-crosslinking method capable of introducing crosslinking between chains of the absorbent polymer during polymerization, and a postcrosslinking method of crosslinking 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 an appropriate chain length, it is possible to prepare an absorbent resin having high absorbency while maintaining excellent gel strength.

As the crosslinking agent which can be crosslinked as the first crosslinking agent, any compound monomer capable of introducing a crosslinking bond during the polymerization and an α, β-unsaturated carboxylic acid monomer can 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 first crosslinking agent content used is preferably 0.001 to 2.0 parts by weight of the first crosslinking agent 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.

In the case of the first crosslinking reaction, the crosslinking reaction temperature is preferably 20 to 120 ° C, and the polymerization reaction is completed within 1 minute to 4 hours.

Referring to Figure 1, after the step of producing a gel-type resin (S11) to subdivide the gel-type resin to produce a fine gel-type resin (S12).

The grinders 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 a shear formed by a plurality of rotary blades and fixed blades is particularly preferred.

The average particle size of the finely divided micelle gel resin is preferably 1 to 20 mm.

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

Drying and pulverizing the fine gel resin to produce a base resin powder (S13) is included in the method of preparing the absorbent resin of the present invention.

In the present invention, the drying of the microgel resin is in the range of 50 to 250 ° C, more preferably in the range of 100 to 170 ° C. If the drying temperature is less than 50 ° C., this shortage 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 that can be used for such heat treatment, a grooved type mixing drier, a rotary dryer, a disk dryer, a fluid bed dryer, an airflow dryer, an infrared dryer, or the like can be used.

The method of subdividing the gel resin can be used equally for grinding after drying of the microgel resin.

The average particle size of the base resin powder is preferably 100 to 850 μm. For this purpose, the ground resin powder is classified and shaken with a standard mesh for each size so as to have an average particle size of 100 to 850 μm.

Surface cross-linking the base resin powder with a polyhydric alcohol type second crosslinking agent at a relative humidity of 0.1 to 2% at a temperature of 100 to 170 ° C. to produce an absorbent resin (S14) may be included in the method for preparing the absorbent resin of the present invention. have.

The reason why the surface crosslinking temperature can be lowered by lowering the relative humidity during the surface crosslinking reaction of the base resin powder is as follows.

In the surface crosslinking reaction according to the preferred embodiment of the present invention, the ester group is reacted with the carboxylic acid group of polyacrylic acid (r1) and the alcohol group of polyhydric alcohol (r2), the second crosslinking agent for surface crosslinking, as in Scheme 1. It is a reaction in which a compound (p1) having and water (p2) are produced.

[Reaction Scheme 1]

Figure 112009067792284-pat00001

This reaction is a reversible reaction. The removal of water (p2) increases the rate of forward reaction and allows the reaction to proceed at lower reaction temperatures. Therefore, lowering the relative humidity of the reactor during the surface crosslinking reaction, water generated during the reaction is easily removed, so that a positive reaction occurs quickly and the surface crosslinking reaction can be easily performed at a low reaction temperature.

Second cross-link

The second crosslinking agent is a polyhydric alcohol and reacts with the carboxyl group of the alkali metal salt of the acrylate alkali polymer, for example, ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, tetraethylene glycol, propane diol, dipropylene glycol, poly Propylene glycol, glycerin, polyglycerol, butanediol, heptanediol, hexanediol trimethylolpropane, pentaerythritol, or sorbitol may be used alone or in combination of two or more, but is not limited thereto.

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 humidity in the reactor during the second crosslinking reaction is 0.1 to 2%, more preferably 0.5 to 2%, even more preferably 1.0 to 1.5%. Relative humidity can be lowered by controlling the amount of air, flow rate and humidity that are put into the reactor. In order to make the relative humidity less than 0.1, it is difficult to control the amount of air and the flow rate, and when the relative humidity exceeds 2%, it is not easy to perform the reaction quickly at low temperature.

In the case of the second crosslinking reaction, the reaction temperature is preferably 100 to 170 ° C, more preferably 150 to 160 ° C. The polymerization reaction can be completed within 1 minute to 4 hours. If the reaction temperature is less than 100 ℃, the reaction is difficult to occur even if the relative humidity is lowered, and if it exceeds 170 ℃, the physical properties of the resulting absorbent resin may be lowered, manufacturing costs may increase, or foreign matters may occur due to browning. .

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.

According to the present invention, there can be provided a method for producing an absorbent resin, characterized in that the average particle size of the absorbent resin is 150 to 850μm, provides an absorbent resin having an average particle size of 150 to 850μm prepared in accordance with the present invention. . The reason for taking 150 ~ 850μm by classification is that when the super absorbent resin is used for diaper, the particles less than 150μm may come out of the diaper cover sheet and come into contact with the skin. The film may be torn.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Such variations and modifications are intended to be within the scope of the appended claims.

Example  One

A water-soluble unsaturated monomer aqueous solution was prepared by adding 1.25 g of triethylene glycol diacrylate as an internal crosslinking agent to 500 g of acrylic acid and dissolving it, and then adding 896.4 g of 24.5% sodium hydroxide solution. The aqueous water-soluble unsaturated monomer aqueous solution was supplied to a 5 L twin arm kneader having a sigma shaft, and nitrogen gas was added for 30 minutes while maintaining at 80 ° C. to remove oxygen dissolved in the aqueous solution. While stirring, 40 g of an aqueous solution containing 1.25 g of potassium persulfate and 3.0 g of hydrogen peroxide were added to 35 g of 0.3% L-ascorbic acid aqueous solution and 100 g of water.

The polymerization was started after 20 seconds, and the resulting gel resin was finely divided for 30 minutes using shear force to prepare a microgel resin. The obtained microgel resin was spread out on a stainless wire gauze having a pore size of 600 μm in a thickness of about 30 mm and dried in a 160 ° 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 standard to obtain a base resin powder having a particle size of 150 µm to 850 µm.

100 g of the obtained base resin powder was mixed evenly with 2.0 g of ethylene glycol, 5.0 g of methanol, 4.0 g of water, 0.3 g of oxalic acid, and 0.02 g of silica, followed by drying for 60 minutes in a 1.5% relative humidity hot air oven. I was. The dried powder was classified into a standard mesh of ASTM standard to obtain an absorbent resin powder having a particle size of 150 µm to 850 µm.

Example  2

100 g of the base resin powder obtained in Example 1 was mixed evenly, adding 2.0 g of propanediol, 5.0 g of methanol, 4.0 g of water, 0.3 g of oxalic acid, and 0.02 g of silica, followed by mixing at a relative humidity of 1.5% and a hot air oven of 170 ° C. The reaction was allowed to dry for 60 minutes. The dried powder was classified into a standard mesh of ASTM standard to obtain an absorbent resin having a particle size of 150 µm to 850 µm.

Example  3

100 g of the base resin powder obtained in Example 1 was mixed evenly with 0.7 g of ethylene glycol, 1.3 g of propane diol, 5.0 g of methanol, 4.0 g of water, 0.3 g of oxalic acid, and 0.02 g of silica, followed by a relative humidity of 1.5%, The reaction was dried for 60 minutes in a 160 ° C. hot air oven. The dried powder was classified into a standard mesh of ASTM standard to obtain an absorbent resin having a particle size of 150 µm to 850 µm.

Example  4

To 500 g of acrylic acid, 0.4 g of 1,6-hexanediol diacrylate and 0.8 g of triethylene-glycol diacrylate were dissolved as an internal crosslinking agent, followed by dissolving 896.4 g of a 24.5% sodium hydroxide solution. Was prepared. The aqueous water-soluble unsaturated monomer solution was supplied to a 5 L twin twin kneader having a sigma shaft, and nitrogen gas was added for 30 minutes while maintaining at 80 ° C. to remove oxygen dissolved in the aqueous solution. While stirring, 40 g of an aqueous solution containing 1.25 g of potassium persulfate and 3.0 g of hydrogen peroxide was added to 35 g of 0.3% L-ascorbic acid aqueous solution and 100 g of water.

The polymerization was started after 20 seconds, and the resulting gel was finely divided for 30 minutes using shear force to prepare a microgel resin.

The prepared microgel resin was spread on a stainless wire gauze having a pore size of 600 μm in a thickness of about 30 mm and dried in a 160 ° 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 standard to obtain a base resin powder having a particle size of 150 µm to 850 µm.

100 g of the obtained base resin powder was mixed evenly with 1.0 g of propanediol, 5.0 g of methanol, 4.0 g of water, 0.3 g of oxalic acid, and 0.02 g of silica, followed by drying for 60 minutes in a 1.0% relative humidity hot air oven at a relative humidity of 1.0%. Reacted. The dried powder was classified into a standard mesh of ASTM standard to obtain an absorbent resin powder having a particle size of 150 µm to 850 µm.

Example  5

100 g of the absorbent resin powder (5) obtained in Example 4 were mixed evenly while adding a mixed solution of 1.0 g of propanediol, 5.0 g of methanol, 4.0 g of water, 0.3 g of oxalic acid, and 0.02 g of silica, followed by a relative humidity of 1.5% and 160 ° C. It was dried in a hot air oven for 60 minutes. The dried powder was classified into a standard mesh of ASTM standard to obtain an absorbent resin having a particle size of 150 µm to 850 µm.

Comparative Example  One

100 g of the base resin powder obtained in Example 1 was mixed evenly while adding a mixed solution of 1.0 g of propanediol, 5.0 g of methanol, 4.0 g of water, 0.3 g of oxalic acid, and 0.02 g of silica, followed by mixing at a relative humidity of 3% and a hot air oven of 170 ° C. The reaction was allowed to dry for 60 minutes. The dried powder was classified into a standard mesh of ASTM standard to obtain an absorbent resin having a particle size of 150 µm to 850 µm.

Comparative Example  2

100 g of the base resin powder obtained in Example 4 was mixed evenly while adding a mixed solution of 2.0 g of ethylene glycol, 5.0 g of methanol, 4.0 g of water, 0.3 g of oxalic acid, and 0.02 g of silica, followed by 60% in a 60% hot air oven at a relative humidity of 3%. The reaction was allowed to dry for a minute. The dried powder was classified into a standard mesh of ASTM standard to obtain an absorbent resin powder having a particle size of 150 µm to 850 µm.

≪ Method for measuring physical properties &

0.3 psi Pressure absorption ability  How to measure

Put 0.2g of 300㎛ ~ 600㎛ absorbent resin into the cylinder with the bottom of the wire mesh and pressurize it with a weight of 0.3psi. Then, after swelling in 0.9% saline for 60 minutes in a pressurized state, the weight of the saline absorbed by the absorbent resin was measured and described in Table 1.

Function  How to measure

0.1 g of absorbent resin of 300 µm to 600 µm is placed in a tea bag, and then the inlet is sealed. The tea bag containing the absorbent resin is swelled for 30 minutes in 0.9% saline. After 30 minutes, take the tea bag out of the brine and put it in the dehydrator. After 3 minutes, the tea bag was taken out of the dehydrator, and the weight of the saline retained by the absorbent resin was measured.

Figure 112009067792284-pat00002

Referring to Table 1, the absorbent resins prepared in Examples 1 to 3 showed relatively high pressure absorption capacity of 0.3psi even though the same base resin was used as in Comparative Example 1, and the absorbent resins prepared in Examples 4 and 5 were also high. The pressure absorption capacity of 0.3 psi higher than that of Comparative Example 2 using the same base resin was shown.

In general, superabsorbent polymer resins undergo surface cross-linking reactions using a second crosslinking agent in the base resin, and when crosslinking occurs, the water holding capacity is somewhat lower than that of the base resin. That is, 0.3 psi pressure absorption capacity is increased.

In view of the physical properties of the examples, the higher the 0.3psi pressure-absorbing capacity of the absorbent resins prepared in Examples 1-5 than the comparative example shows that the crosslinking reaction occurred better. The crosslinking reaction of the above example takes place as an esterification reaction of the base resin with a crosslinking agent having a polyhydric alcohol, which is generally efficient at a temperature of 180 ° C. or higher.

However, there is a problem that the physical properties of the absorbent resin generated during the reaction at high temperature, or the manufacturing cost is increased to increase the temperature of the reactor, and also the foreign matter generation due to browning of the product due to the high temperature. In Examples 1 to 5 by lowering the relative humidity during the reaction to promote the removal of water generated during the reaction, crosslinking reaction at a relatively low temperature to minimize this problem, it was possible to improve the pressure absorption capacity of 0.3psi.

1 is a view schematically showing the manufacturing process of the absorbent resin of the present invention.

Claims (12)

  1. (A) generating a gel-type resin by internal crosslinking of an aqueous acrylic acid monomer solution including an acidic group with a first crosslinking agent;
    Subdividing the gel resin to produce a fine gel resin (b);
    Drying and grinding the fine gel resin to produce a base resin powder (c);
    (E) surface-crosslinking the base resin powder with a polyhydric alcohol type second crosslinking agent at a relative humidity of 0.1 to 2% at a temperature of 100 to 170 ° C to produce an absorbent resin;
    Method for producing an absorbent resin comprising a.
  2. The method of claim 1, wherein the step (e) of generating the absorbent resin comprises cross-linking the base resin powder at a temperature of 150 to 160 ° C to produce an absorbent resin.
  3. The method of claim 1 or 2, wherein the acrylic acid monomer is represented by the following formula (1).
    [Formula 1]
    R 1 -COOM 1
    In Formula 1, R 1 is a hydrocarbon group of 2 to 5 carbon atoms containing an unsaturated bond, M 1 is a hydrogen atom, a monovalent or divalent metal, an ammonium group or an organic amine salt
  4. The water absorbent according to claim 1 or 2, wherein the acrylic acid monomer is at least one member selected from the group consisting of acrylic acid, methacrylic acid, monovalent metal salts, divalent metal salts, ammonium salts and organic amine salts of these acids. Method for producing a resin.
  5. The method of claim 1 or 2, wherein the aqueous acrylic acid monomer solution of step (a) is a 40 to 90 mol% neutralized acrylic acid monomer aqueous solution.
  6. The first crosslinking agent according to claim 1 or 2, wherein the first crosslinking agent is 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, hexane Diol 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 the process for producing a water-absorbent resin, characterized in that at least one member selected from the group consisting of ethylene carbonate.
  7. The method of claim 1 or 2, wherein the crosslinking temperature of step (a) is 20 to 120 ℃.
  8. The method of claim 1 or 2, wherein the average particle size of the microgel resin is 1 to 20 mm.
  9. The method of claim 1 or 2, wherein the base resin powder has an average particle size of 100 to 850 µm.
  10. The polyhydric alcohol-type second crosslinking agent is ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, tetraethylene glycol, propane diol, dipropylene glycol, polypropylene glycol, glycerin, poly. Method for producing an absorbent resin, characterized in that at least one selected from the group consisting of glycerin, butanediol, heptanediol, hexanediol trimethylolpropane, pentaerythritol and sorbitol.
  11. The method for producing an absorbent resin according to claim 1 or 2, wherein the average particle size of the absorbent resin is 150 to 850 µm.
  12. delete
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