KR101812895B1 - Method of Manufacturing for Super Absorption Polymer - Google Patents

Abstract

Disclosed is a method of manufacturing high-absorptive resin by polymerizing a monomer composition including an acrylic acid monomer composition, a polymerization initiator, a foaming agent, and a nonionic surfactant, and then, making the composition go through smashing, drying, and cross-linking procedures. The present invention includes: a step (a) of forming a function gel-phase polymer by thermally or optically polymerizing a monomer composition including an acrylic acid monomer composition, which has partially neutralized acidity, a first cross-linking agent, a polymerization initiator, a foaming agent, and a nonionic surfactant; a step (b) of smashing the function gel-phase polymer; a step (c) of drying the smashed polymer at 150-250C; a step (d) of drying the dried polymer; and a step (e) of making a surface cross-linking reaction to the smashed polymer under the existence of a second cross-linking agent.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention relates to a method for producing a superabsorbent resin, and more particularly, to a method for producing a superabsorbent resin by polymerizing a monomer composition comprising an acrylic acid monomer composition, a polymerization initiator, a foaming agent and a nonionic surfactant and then pulverizing, And a method for producing the same.

Super absorbent polymer (SAP) is a synthetic polymer material capable of absorbing a level of about 500 to 1,000 times its own weight. As a result, a super absorbent material (SAM), an absorbent gel material) and so on. Such a superabsorbent resin has begun to be put to practical use as a sanitary article and is currently being used in various fields such as a sanitary article for children's paper diapers and the like, a soil repair agent for horticultural use, a soil index material for civil engineering, It is widely used as a material.

Such a method of producing a superabsorbent resin includes a thermal polymerization method in which a hydrogel polymer is polymerized while being broken and cooled in a kneader-type reactor provided with several shafts, a polymerization method in which ultraviolet rays are irradiated onto a high- And a method of producing a superabsorbent resin by suspension polymerization are known.

Such a superabsorbent resin can be produced through polymerization, drying, pulverization, classification, and surface cross-linking processes. In order to improve the absorption ability, it was tried to improve the absorption ability by studying the crosslinking agent in the polymerization process, studying the surface area improvement in crushing and classification, and studying the improvement of the surface crosslinking. However, despite these studies, there has been a limit to improving the absorption ability of the acrylic-based superabsorbent resin.

Korean Patent Laid-Open Publication No. 2015-0082098 (2015.07.15) Korean Patent Laid-Open Publication No. 2015-0088219 (Jul. 31, 2015) International Patent Publication No. WO2015-047029 (2014.09.30)

Disclosure of the Invention The present invention has been made to solve the above problems, and it is an object of the present invention to provide a method for polymerizing a monomer composition comprising a polymerization initiator, a foaming agent and a nonionic surfactant in an acrylic acid monomer composition, followed by pulverization, Absorbent resin which is excellent in absorption rate without deteriorating water retention capacity and pressure absorption ability.

(A) a monomer composition comprising an acrylic acid-based monomer composition having an acidic group and at least a part of the acidic groups neutralized, a first crosslinking agent, a polymerization initiator, a foaming agent and a nonionic polymer type surfactant Thermally polymerizing or photopolymerizing the functional gel polymer to form a hydrogel polymer; (b) pulverizing the hydrogel polymer; (c) drying the pulverized polymer at 150 to 250 占 폚; (d) pulverizing the dried polymer; And (e) surface cross-linking the ground polymer in the presence of a second crosslinking agent.

Wherein the superabsorbent resin has a CRC of 25 g / g or more, a pressure absorption capacity (AUL) of 15 g / g or more, and an absorption rate of 20 g / g of 150 seconds or less to provide.

Also, the nonionic polymer type surfactant is a block copolymer type surfactant in which one block is a water-soluble polymer.

The nonionic polymer type surfactant may be a block copolymer composed of at least one water-soluble polymer selected from the group consisting of polyethylene glycol derivatives, polyvinyl alcohol derivatives, polyacrylamide derivatives, polyvinylpyrrolidone derivatives and polyhydroxyacrylate derivatives. Wherein at least one of the water-absorbent resin and the water-absorbent resin is used.

Also, the nonionic polymer type surfactant is characterized in that at least one diblock copolymer or triblock copolymer composed of polyethylene glycol and polypropylene glycol is used.

Also, the nonionic polymer type surfactant has an HLB value of 3 to 20.

And the molecular weight of the nonionic polymer type surfactant is 500 to 30,000.

The acrylic acid-based monomer is represented by the following general formula (1).

[Chemical Formula 1]

R1-COOM

(Wherein R 1 is an alkyl group having 2 to 5 carbon atoms containing an unsaturated bond, M is a hydrogen atom, a monovalent or divalent metal, an ammonium group or an organic amine salt)

The first crosslinking agent may be at least one selected from the group consisting of N, N'-methylenebisacrylamide, trimethylolpropane tri (meth) acrylate, ethylene glycol di (meth) acrylate, polyethylene glycol (meth) acrylate, propylene glycol di Butene diol 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 tetra Acrylate, triarylamine, ethylene glycol diglycidyl ether, propylene glycol, glycerin, and And characterized in that at least one member selected from the group consisting of alkylene carbonate provides a process for the production of water-absorbent resin.

The second crosslinking agent may be at least one selected from the group consisting of ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol polyglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, ethylene glycol, But are not limited to, ethylene glycol, propylene glycol, triethylene glycol, tetraethylene glycol, propanediol, dipropylene glycol, polypropylene glycol, glycerin, polyglycerin, butanediol, heptanediol, hexanediol trimethylolpropane, Sorbitol, and sorbitol. The present invention also provides a method for producing a superabsorbent resin.

The ratio of the blowing agent to the polymer type surfactant is 0.1: 1 to 1: 0.1.

The blowing agent may be selected from the group consisting of sodium bicarbonate, sodium carbonate, potassium bicarbonate, potassium carbonate, calcium bicarbonate, calcium bicarbonate, magnesium carbonate, Characterized in that it is magnesium carbonate or magnesium bicarbonate or magnesium carbonate.

According to the present invention, since a specific surfactant is contained in the acrylic acid monomer composition, it is possible to produce a water-saving bag and a superabsorbent resin excellent in absorption ability and pressure absorption ability, Sheets, absorbent paper for food, and the like.

Hereinafter, preferred embodiments of the present invention will be described in detail. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Throughout the specification, when an element is referred to as "including " an element, it means that it can include other elements, not excluding other elements, unless specifically stated otherwise.

The present inventors have observed that the existing acrylic high-humidity water-based resins have lower absorption performance than other water-absorbent materials. As a result, they have found that when a water-absorbent resin is prepared by adding a specific surfactant to an acrylic resin The present inventors have confirmed that the absorption capacity is greatly improved as compared with the conventional water absorbent resin, and the present invention has been completed.

Hereinafter, the present invention will be described in detail.

The present invention relates to a method for producing a thermosetting resin composition which comprises (a) thermally polymerizing or photopolymerizing a monomer composition comprising an acrylic acid-based monomer composition having an acidic group and at least a part of the acidic groups neutralized, a first crosslinking agent, a polymerization initiator, a foaming agent and a nonionic polymer type surfactant Forming a hydrogel polymer; (b) pulverizing the hydrogel polymer; (c) drying the pulverized polymer at 150 to 250 占 폚; (d) pulverizing the dried polymer; And (e) subjecting the ground polymer to surface cross-linking in the presence of a second cross-linking agent.

Hereinafter, the present invention will be described in detail.

Hydrogel  The step of forming the polymer (step 1)

The method for producing the superabsorbent resin includes a step of thermally polymerizing or photopolymerizing a monomer composition comprising an acrylic acid monomer and a monomer composition comprising a polymerization initiator, a crosslinking agent, a foaming agent and a polymer type surfactant to form a hydrogel polymer do.

The water-soluble acrylic acid-based monomer contained in the monomer composition may be any monomer conventionally used in the production of a superabsorbent resin. As a non-limiting example, the water-soluble acrylic acid-based monomer may be a compound represented by the general formula (1).

[Chemical Formula 1]

R1-COOM

(Wherein R 1 is an alkyl group having 2 to 5 carbon atoms containing an unsaturated bond, M is a hydrogen atom, a monovalent or divalent metal, an ammonium group or an organic amine salt)

The monomer may be at least one selected from the group consisting of acrylic acid, methacrylic acid, monovalent metal salts of these acids, divalent metal salts, ammonium salts and organic amine salts. When acrylic acid or a salt thereof is used as the water-soluble acrylic acid-based unsaturated monomer as described above, it is advantageous to obtain a highly water-absorbent resin having improved water absorption. Examples of the monomer include 2-acryloylethanesulfonic acid, 2-methacryloylethanesulfonic acid, 2- (meth) acryloylpropanesulfonic acid, 2- (meth) acrylamide- (Meth) acrylate, methoxypolyethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate, 2-hydroxyethyl Acrylate, (N, N) -dimethylaminoethyl (meth) acrylate, and (N, N) -dimethylaminopropyl (meth) acrylamide.

The acrylic acid-based monomer may have an acidic group and at least a part of the acidic group may be neutralized. Preferably, the monomer is partially neutralized with an alkylene material such as sodium hydroxide, potassium hydroxide, ammonium hydroxide or the like. At this time, the neutralization degree of the acrylic acid monomer may be 40 to 95 mol%, preferably 40 to 80 mol%, more preferably 45 to 75 mol%. The range of the degree of neutralization can be adjusted according to the final properties. If the degree of neutralization is too high, it may be difficult for polymerization to proceed smoothly due to precipitation of neutralized monomers. On the other hand, if the degree of neutralization is too low, the absorption capacity of the polymer is greatly lowered, .

The concentration of the acrylic acid monomer in the monomer composition may be appropriately controlled in consideration of the polymerization time and the reaction conditions, and may be preferably 10 to 95% by weight, more preferably 50 to 90% by weight. Such a concentration range may be advantageous in controlling the grinding efficiency of the subsequent process polymer, while eliminating the need to remove unreacted monomers after polymerization using the gel phenomenon that occurs in the polymerization of high concentration aqueous solutions. However, if the concentration of the monomer is excessively low, the yield of the superabsorbent resin may be lowered. On the other hand, if the concentration of the monomer is excessively high, a part of the monomer may precipitate or the pulverization efficiency may be lowered upon pulverization of the polymer gel, and the physical properties of the superabsorbent resin may be deteriorated.

The monomer composition may include a polymerization initiator generally used in the production of a superabsorbent resin. As a non-limiting example, as the polymerization initiator, a thermal polymerization initiator or a photopolymerization initiator may be used depending on the polymerization method. However, even with the photopolymerization method, a certain amount of heat is generated by ultraviolet irradiation or the like, and a certain amount of heat is generated as the polymerization reaction, which is an exothermic reaction, proceeds, so that a thermal polymerization initiator may further be included.

Examples of the photopolymerization initiator include benzoin ether, dialkyl acetophenone, hydroxyl alkylketone, phenyl glyoxylate, benzyldimethyl ketal At least one compound selected from the group consisting of benzyl dimethyl ketal, acyl phosphine and alpha-aminoketone may be used.

As the thermal polymerization initiator, at least one compound selected from the group consisting of a persulfate-based initiator, an azo-based initiator, hydrogen peroxide, and ascorbic acid may be used. Specifically, examples of the persulfate-based initiator include sodium persulfate (Na2S2O8), potassium persulfate (K2S2O8), and ammonium persulfate (NH4) 2S2O8. Azo-based initiators include 2,2-azobis (2-amidinopropane) dihydrochloride, 2,2-azobis- (N, N-dimethylene isobutyramidine dihydrochloride, 2- (carbamoylazo) isobutylonitrile, 2,2-azobis- (N, N-dimethylene) isobutyramidine dihydrochloride, Azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride), 4,2-diazabicyclo [ 4-azobis- (4-cyanovaleric acid), and the like.

Such a polymerization initiator may be added at a concentration of about 0.001 to 1% by weight based on the monomer composition. That is, if the concentration of the polymerization initiator is too low, the polymerization rate may be slowed and the remaining monomer may be extracted in the final product in a large amount, which is not preferable. On the contrary, when the concentration of the polymerization initiator is too high, the chain of the polymer forming the network is shortened, and the physical properties of the resin may be lowered, such that the content of the water-soluble component is increased and the pressure absorption capacity is lowered.

On the other hand, the monomer composition includes a first crosslinking agent for improving physical properties of the hydrogel polymer. The first cross-linking agent is used as an internal cross-linking agent for cross-linking the hydrous gel-like polymer with the inside, and is used separately from the second cross-linking agent (cross-linking agent) for cross- linking the surface of the hydrous gel-like polymer in a subsequent step.

The first crosslinking agent is selected from the group consisting of N, N'-methylenebisacrylamide, trimethylolpropane tri (meth) acrylate, ethylene glycol di (meth) acrylate, polyethylene glycol (meth) acrylate, propylene glycol di (Meth) acrylate, diethylene glycol di (meth) acrylate, hexane diol di (meth) acrylate, butane diol di (meth) acrylate, (Meth) acrylate such as triethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, dipentaerythritol pentaacrylate, glycerin tri Triarylamine, ethylene glycol diglycidyl ether, propylene glycol, glycerin, and ethylene carbonate And at least one selected from the group consisting of borates.

Such an internal cross-linking agent may be added at a concentration of about 0.001 to 1% by weight based on the monomer composition. That is, when the concentration of the internal cross-linking agent is too low, the absorption rate of the resin may be lowered and the gel strength may be weakened. On the contrary, when the concentration of the internal cross-linking agent is too high, the absorption power of the resin is lowered, which may be undesirable as an absorber.

The blowing agent may be selected from the group consisting of sodium bicarbonate, sodium carbonate, potassium bicarbonate, potassium carbonate, calcium bicarbonate, calcium bicarbonate, Magnesium bicarbonate or magnesium carbonate may be used.

The nonionic polymer type surfactant may be a block copolymer type surfactant in which one block is a water-soluble polymer. Specific examples of the nonionic polymer type surfactant include polyethylene glycol, polyvinyl alcohol, polyacrylamide polyvinylpyrrolidone, Acrylate, polyacrylic acid, polyvinylsulfonic acid, and the like. The water-soluble polymer may be a block copolymer composed of at least one water-soluble polymer selected from the group consisting of acrylate, polyacrylic acid and polyvinylsulfonic acid. Preferably, at least one diblock copolymer or triblock copolymer composed of polyethylene glycol and polypropylene glycol may be used. The nonionic polymer type surfactant may have an HLB value of 3 to 20, preferably 3 to 15, more preferably 4 to 10.

In addition, the nonionic polymer type surfactant may have a molecular weight of 500 to 30,000. If the molecular weight of the nonionic polymer type surfactant is less than 500 or more than 30,000, the effect of the surfactant may be reduced, resulting in poor foam stability and microporous stability, and thus, absorption performance and stability may be deteriorated.

In addition, the monomer composition may further contain additives such as a thickener, a plasticizer, a storage stabilizer, and an antioxidant, if necessary.

At this time, usable solvents may be used without limitation of the constitution as long as they can dissolve the above-mentioned raw materials. Examples of the solvent include water, ethanol, ethylene glycol, diethylene glycol, triethylene glycol, 1,4-butanediol, propylene glycol, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate Methyl ethyl ketone, acetone, methyl amyl ketone, cyclohexanone, cyclopentanone, diethylene glycol monomethyl ether, diethylene glycol ethyl ether, toluene, xylene, butyrolactone, carbitol, methyl cellosolve acetate, N, N-dimethylacetamide, or a mixture thereof may be used

The formation of the hydrogel polymer through polymerization of the monomer composition can be carried out by a conventional polymerization method, and the process is not particularly limited. As a non-limiting example, the polymerization method is divided into thermal polymerization and photopolymerization depending on the type of polymerization energy source. In the case of conducting the thermal polymerization, the polymerization may proceed in a reactor having a stirring axis such as a kneader, It is possible to proceed in a reactor equipped with a movable conveyor belt.

Hydrogel  The step of pulverizing the polymer (step 2)

The hydrogel polymer obtained through the above-mentioned steps is subjected to a drying process for imparting water absorbency. However, in order to increase the efficiency of such drying, a step of pulverizing the hydrogel polymer is carried out before the drying process is performed.

As a non-limiting example, the pulverizers usable for the above coarse grinding include a vertical pulverizer, a turbo cutter, a turbo grinder, a rotary cutter mill, Examples thereof include a cutter mill, a disc mill, a shred crusher, a crusher, a chopper, and a disc cutter.

At this time, the pulverization can be performed so that the diameter of the hydrogel polymer is 2 mm to 10 mm. That is, in order to increase the drying efficiency, the hydrogel polymer is preferably pulverized into particles of 10 mm or less. However, since excessive aggregation may occur during the pulverization, the hydrogel polymer is preferably pulverized into particles of 2 mm or more.

Since the crude pulverization step is carried out at a high moisture content of the polymer, the polymer may stick to the surface of the pulverizer. In order to minimize such a phenomenon, steam, water, a surfactant, an anti-aggregation agent (for example, clay, silica, etc.) may be added to the coarse grinding step, if necessary. A cross-linking agent containing an acrylate of a bifunctional group or a polyfunctional group having three or more functional groups, a cross-linking agent containing a hydroxyl group, a cross-linking agent containing a hydroxyl group, a cross-linking agent containing a hydroxyl group, Etc. may be added.

Hydrogel  The step of drying the polymer (step 3)

The step of drying the coarse pulverized hydrogel polymer is carried out through the steps described above. As the hydrogel polymer is supplied to the drying step in a state of being pulverized into particles of 2 mm to 10 mm through the above-mentioned steps, drying can be performed with higher efficiency.

The drying of the coarse hydrogel polymer may be carried out at a temperature of 120 to 250 ° C, preferably 130 to 200 ° C. The drying temperature may be defined as the temperature of the heat medium supplied for drying or the temperature inside the drying reactor including the heat medium and the polymer in the drying process. If the drying temperature is low and the drying time is long, the process efficiency is lowered. To prevent this, the drying temperature is preferably 120 ° C or more. In addition, when the drying temperature is higher than necessary, the surface of the hydrogel polymer is excessively dried, so that the generation of fine powder may be increased in the subsequent grinding step and the physical properties of the final resin may be lowered. To prevent this, It is preferable that the temperature is 250 DEG C or less.

At this time, the drying time in the drying step is not particularly limited, but may be adjusted to 20 to 90 minutes under the drying temperature in consideration of process efficiency and the like.

The drying method of the drying step may be applied to the drying method of the hydrogel polymer as long as it can be used normally. Specifically, the drying step may be performed by hot air supply, infrared irradiation, microwave irradiation, ultraviolet irradiation, or the like.

The polymer dried in this way may exhibit a water content of about 0.1 to 10% by weight. That is, when the water content of the polymer is less than 0.1% by weight, an increase in the manufacturing cost due to excessive drying and degradation of the cross-linking polymer may occur, which is not advantageous. If the water content of the polymer exceeds 10% by weight, defects may occur in the subsequent step, which is not preferable.

Hydrogel  Crushing the polymer (step 4)

The pulverization step is a step for optimizing the surface area of the dried polymer, and may be carried out such that the particle diameter of the pulverized polymer is 150 to 850 mu m. The pulverizer usable for crushing with such a particle size may be a pin mill, a hammer mill, a screw mill, a roll mill, a disc mill, a jog mill jog mill) and the like.

Further, in order to manage the physical properties of the superabsorbent resin to be finally produced, the step of selectively classifying particles having a particle diameter of 150 to 850 mu m in the polymer powder obtained through the pulverization step may be further performed.

Step (5) of surface-crosslinking the pulverized polymer,

The surface cross-linking can be carried out by a method of increasing the cross-linking density of the resin particle surface by mixing the solution containing the second cross-linking agent (surface cross-linking agent) with the above-mentioned pulverized polymer and performing a cross-linking reaction.

Here, the kind of the second cross-linking agent (surface cross-linking agent) contained in the surface cross-linking solution is not particularly limited. Non-limiting examples of the surface cross-linking agent include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol polyglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, ethylene The organic solvent may be selected from the group consisting of a carbonate, an ethylene glycol, a diethylene glycol, a propylene glycol, a triethylene glycol, a tetraethylene glycol, a propanediol, a dipropylene glycol, a polypropylene glycol, a glycerin, a polyglycerin, a butanediol, At least one compound selected from the group consisting of propane, pentaerythritol, sorbitol, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, iron oxide, calcium chloride, magnesium chloride, aluminum chloride and iron chloride.

At this time, the content of the surface cross-linking agent may be appropriately adjusted according to the type of cross-linking agent, reaction conditions, etc., and preferably 0.001 to 5 parts by weight based on 100 parts by weight of the ground polymer. If the content of the surface cross-linking agent is too low, the surface cross-linking may not be properly introduced, and the physical properties of the final resin may be deteriorated. On the contrary, if the surface cross-linking agent is used in an excessive amount, the absorption force of the resin may be lowered due to excessive surface cross-linking reaction, which is not preferable.

On the other hand, in order to carry out the surface cross-linking reaction step, a method of mixing the surface cross-linking solution and the pulverized polymer into a reaction tank and mixing them, a method of spraying a surface cross-linking solution on the pulverized polymer, A method in which the surface cross-linking solution is continuously supplied and mixed, or the like can be used.

Further, water and alcohol may be added when the surface cross-linking solution is added. As such, the addition of water and alcohol together can induce a more even dispersion of the crosslinking agent, prevent the aggregation of the polymer powder, and further optimize the penetration depth of the surface crosslinking agent to the polymer powder. In view of these objects and effects, the content of water to be added can be adjusted to 0.5 to 10 parts by weight based on 100 parts by weight of the ground polymer.

The surface cross-linking reaction step may be carried out at a temperature of 100 to 250 ° C and continuously after the drying and crushing step which proceeds at relatively high temperatures. At this time. The surface cross-linking reaction may be conducted for 1 to 120 minutes, or for 1 to 100 minutes. That is, the surface cross-linking reaction may be carried out in order to prevent the polymer particles from being damaged due to excessive reaction while inducing a minimal surface cross-linking reaction, thereby lowering the physical properties.

In the present invention, the superabsorbent resin preferably has a CRC of 25 g / g or more, more preferably 30 g / g or more, a pressure absorption capacity (AUL) of 15 g / g or more, preferably 20 g / And an absorption rate of 20 g / g is 150 seconds or less, preferably 140 seconds or less.

Example  And Comparative Example

[ Example  One]

50 g of acrylic acid, 50 g of distilled water, and 20 g of sodium hydroxide were added to the reaction vessel, followed by stirring for 30 minutes. After the temperature increased due to the neutralizing heat, the temperature was lowered to about 40 ° C., and 0.1 g of an internal crosslinking agent, trimethylolpropane triacrylate, and 0.1 g of initiator 2 ', 2-azobismethylpropionamidine dihydrochloride (2' 0.05 g of sodium peroxodisulfate and 0.3 g of sodium bicarbonate and 0.3 g of PEG-PPG-PEG (molecular weight 5,800, HLB 8) After 5 minutes of stirring, the polymerization reaction was carried out for 2 minutes at 80 mW / cm 2 using a UV lamp. After about 57 ~ 58 seconds after the polymerization, the foaming proceeded rapidly.

The gel-state polymer after polymerization was cut through a chopper and then dried in a hot air oven at 180 ° C for 2 hours. Then, the dried and hardened polymer was pulverized through a crushing machine and classified into a size of 150 to 850 mu m to prepare a superabsorbent resin.

Then, 5 g of ethylene glycol diglycidyl ether and 85 g of water and 10 g of ethanol were used to prepare a surface cross-linking liquid, and 0.5 g of surface cross-linking liquid was sprayed on the prepared superabsorbent resin. After crosslinking the surface of the superabsorbent resin, it was reacted in an oven at 140 DEG C for 40 minutes and a superabsorbent resin having a surface size of 150 to 850 mu m was produced using a sheave.

[ Example  2]

Except that PEG-PPG-PEG (molecular weight 1,100, HLB 4) was used instead of PEG-PPG-PEG (molecular weight 5,800, HLB 8) in Example 1.

[ Example  3]

Except that PEG-PPG-PEG (molecular weight: 2,000, HLB 4) was used instead of PEG-PPG-PEG (molecular weight 5,800, HLB 8) in Example 1.

[ Example  4]

Except that PEG-PPG-PEG (molecular weight 2,800, HLB 4) was used instead of PEG-PPG-PEG (molecular weight 5,800, HLB 8) in Example 1.

[ Example  5]

Except that PEG-PPG-PEG (molecular weight 2,900, HLB 15) was used instead of PEG-PPG-PEG (molecular weight 5,800, HLB 8) in Example 1.

[ Example  6]

Except that PPG-PEG-PPG (molecular weight 3,300 HLB 4) was used instead of PEG-PPG-PEG (molecular weight 5,800, HLB 8) in Example 1.

[ Example  7]

Except that PPG-PEG-PPG (molecular weight 2,700 HLB 15) was used instead of PEG-PPG-PEG (molecular weight 5,800, HLB 8) in Example 1

[ Example  8]

Except that PPG-PEG-PPG (molecular weight 2,000 HLB 15) was used instead of PEG-PPG-PEG (molecular weight 5,800, HLB 8) in Example 1

[ Example  9]

Except that 0.2 g of Trimethylolpropane triacrylate instead of 0.1 g of the internal cross-linking agent was used in Example 1

[ Example  10]

Except that 0.3 g of Trimethylolpropane triacrylate instead of 0.1 g of the internal cross-linking agent was used in Example 1

[ Example  11]

Except for using 0.05 g instead of 0.1 g of trimethylolpropane triacrylate as an internal cross-linking agent in Example 1

[ Comparative Example  One]

Instead of PEG-PPG-PEG (molecular weight 1,900 HLB 20) instead of PEG-PPG-PEG (molecular weight 5,800, HLB 8) in Example 1 and 0.1 g of trimethylolpropane triacrylate as an internal crosslinking agent The same procedure was performed.

[ Comparative Example  2]

PEG-PPG-PEG (molecular weight: 4,400, HLB 24) was used instead of PEG-PPG-PEG (molecular weight 5,800, HLB 8) in Example 1 and 0.3 g of trimethylolpropane triacrylate The same procedure was followed.

[ Comparative Example  3]

PEG-PPG-PEG (molecular weight: 8,400, HLB 24) was used instead of PEG-PPG-PEG (molecular weight of 5,800 and HLB 8) in Example 1 and 0.3 g of trimethylolpropane triacrylate as an internal cross- The same procedure was followed.

[ Comparative Example  4]

The same procedure was followed except that PEG-PPG-PEG (molecular weight 5,800 and HLB 8) was not used in Example 1

[ Comparative Example  5]

The same procedure was followed except that PEG-PPG-PEG (molecular weight 5,800, HLB 8) was not used in Example 1 but 0.2 g was used instead of 0.1 g of trimethylolpropane triacrylate as an internal crosslinking agent

[ Comparative Example  6]

The same procedure was followed except that PEG-PPG-PEG (molecular weight 5,800, HLB 8) was not used in Example 1 but 0.3 g was used instead of 0.1 g of trimethylolpropane triacrylate as an internal crosslinking agent

[ Comparative Example  7]

Except that PEG-PPG-PEG (molecular weight 5,800, HLB 8) was not used in Example 1 and 0.05 g was used instead of 0.1 g of trimethylolpropane triacrylate as an internal crosslinking agent

[ Comparative Example  8]

The same procedure was followed except that PEG-PPG (molecular weight 5,800, HLB 8) diblock copolymer was used instead of PEG-PPG-PEG (molecular weight 5,800 and HLB 8) in Example 1.

Experimental Example: Properties  evaluation

(1) CRC (Centrifuge Retention Capacity)

According to EDANA method WSP 241.2, the insulating performances of the resins of the above Examples and Comparative Examples were measured. That is, the resin W (g) (about 0.2 g) obtained through the examples and the comparative examples was uniformly put in an envelope made of a nonwoven fabric, sealed, and impregnated with physiological saline (0.9 wt%) at room temperature. After about 30 minutes, water was drained from the envelope for 3 minutes under a condition of 250 G using a centrifuge, and the mass W2 (g) of the envelope was measured. Further, after the same operation was performed without using a resin, the mass W1 (g) at that time was measured. Using the obtained masses, CRC (g / g) was calculated according to the following equation.

 [Equation 1]

CRC (g / g) = {(W2 - W1) / W} - 1

(2) Absorption Under Pressure (AUP)

According to EDANA method WSP 242.3, the pressure absorption capacity of the resins of the above Examples and Comparative Examples was measured. That is, a 400 mesh wire mesh made of stainless steel was attached to the bottom of a plastic cylinder having an inner diameter of 60 mm. The piston capable of uniformly spreading the water absorbent resin W (g) (about 0.90 g) on the wire net and uniformly applying a load of 4.83 kPa (0.7 psi) on the wire net under the conditions of room temperature and humidity of 50% mm so that there is no gap between the inner wall of the cylinder and the up and down movement is not interrupted. At this time, the weight Wa (g) of the device was measured.

A glass filter having a diameter of 90 mm and a thickness of 5 mm was placed inside a petro dish having a diameter of 150 mm, and physiological saline composed of 0.90% by weight sodium chloride was made to have the same level as the upper surface of the glass filter. And a filter paper having a diameter of 90 mm was placed thereon. The measuring device was placed on the filter paper and the liquid was absorbed under load for 1 hour. After one hour, the measuring device was lifted and its weight Wb (g) was measured.

Then, the pressure absorption capacity (g / g) was calculated from the Wa and Wb according to the following equation

 &Quot; (2) "

AUP (g / g) = {Wb - Wa} / W

(3) Absorption rate (T (20): Time required to reach up to 20 g / g)

The absorption rate was measured according to the method disclosed in U.S. Patent Publication No. 2013-0079740, wherein 2 g of the superabsorbent resin prepared in the Examples and Comparative Examples were respectively used.

CRC
(g / g) AUP
(g / g) Absorption rate
20 g / g (sec) Foam stability Example 1 31.4 21.0 137 O Example 2 32.5 20.9 141 O Example 3 32.1 21.1 139 O Example 4 31.9 20.7 140 O Example 5 32.1 21.3 139 O Example 6 31.8 21.2 140 O Example 7 32.1 21.0 138 O Example 8 32.0 21.0 142 O Example 9 30.1 23.7 133 O Example 10 29.0 24.3 137 O Example 11 34.7 17.2 139 O Comparative Example 1 28.4 19.1 158 △ Comparative Example 2 29.1 18.9 160 △ Comparative Example 3 28.6 18.9 160 △ Comparative Example 4 28.7 19.0 159 O Comparative Example 5 27.2 20.4 167 △ Comparative Example 6 26.8 20.9 169 X Comparative Example 7 33.4 16.7 167 X Comparative Example 8 30.1 19.1 165 △

As shown in Table 1, when the HLB of the surfactant is 20 or more, the foam stability is lowered. Also, when 0.2 g or more of the first crosslinking agent (internal crosslinking agent) was used without using a surfactant (Comparative Examples 5 to 7), the foam stability was poor and the absorption rate was also decreased. However, in the case where both of the surfactant and the first crosslinking agent were not used (Comparative Example 4), the physical properties were the same as in Examples, but in this case, the surface tension value of the prepared resin was high, It was confirmed that the strength was lowered. In addition, as shown in Comparative Example 8 in which a binary copolymer was used, when the terpolymer was not used, the foaming performance was lowered and the absorption performance was also decreased.

The preferred embodiments of the present invention have been described in detail above. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Accordingly, the scope of the present invention is defined by the appended claims rather than the foregoing detailed description, and all changes or modifications derived from the meaning, range, and equivalence of the claims are included in the scope of the present invention Should be interpreted.

Claims (12)

A method for producing a superabsorbent resin comprising the steps of:
(a) thermally polymerizing or photopolymerizing a monomer composition comprising an acrylic acid-based monomer composition having an acidic group and at least a part of the acidic groups neutralized, a first crosslinking agent, a polymerization initiator, a foaming agent and a nonionic polymer type surfactant, , Characterized in that the nonionic polymer type surfactant is a triblock copolymer composed of polyethylene glycol and polypropylene glycol;
(b) pulverizing the hydrogel polymer;
(c) drying the pulverized polymer at 150 to 250 占 폚;
(d) pulverizing the dried polymer; And
(e) surface cross-linking the ground polymer in the presence of a second crosslinking agent. The method according to claim 1,
Wherein the superabsorbent resin has a retention capacity (CRC) of 25 g / g or more, a pressure absorption capacity (AUL) of 15 g / g or more, and an absorption rate of 20 g / g or less of 150 seconds or less. delete delete delete The method according to claim 1,
Wherein the nonionic polymer type surfactant has an HLB value of 3 to 20. The method according to claim 1,
Wherein the nonionic polymer type surfactant has a molecular weight of 500 to 30,000. The method according to claim 1,
Wherein the acrylic acid-based monomer is represented by the following formula (1).
[Chemical Formula 1]
R1-COOM
(Wherein R 1 is an alkyl having 2 to 5 carbon atoms containing an unsaturated bond, M is a hydrogen atom, a monovalent or divalent metal, an ammonium group or an organic amine salt) The method according to claim 1,
The first crosslinking agent is selected from the group consisting of N, N'-methylenebisacrylamide, trimethylolpropane tri (meth) acrylate, ethylene glycol di (meth) acrylate, polyethylene glycol (meth) acrylate, propylene glycol di (Meth) acrylate, diethylene glycol di (meth) acrylate, hexane diol di (meth) acrylate, butane diol di (meth) acrylate, (Meth) acrylate such as triethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, dipentaerythritol pentaacrylate, glycerin tri Triarylamine, ethylene glycol diglycidyl ether, propylene glycol, glycerin, and ethylene carbonate Wherein the water-insoluble resin is at least one selected from the group consisting of sodium carbonate, sodium carbonate, and sodium carbonate. The method according to claim 1,
Wherein the second crosslinking agent is selected from the group consisting of ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol polyglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, ethylene glycol, diethylene Butylene glycol, propylene glycol, triethylene glycol, tetraethylene glycol, propanediol, dipropylene glycol, polypropylene glycol, glycerin, polyglycerin, butanediol, heptanediol, hexanediol trimethylolpropane, pentaerythritol, sorbitol Wherein the water-absorbent resin is at least one selected from the group consisting of water-soluble polymer and water-soluble polymer. The method according to claim 1,
Wherein the ratio of the blowing agent to the high-molecular surfactant is from 0.1: 1 to 1: 0.1. The method according to claim 1,
The foaming agent may be selected from the group consisting of sodium bicarbonate, sodium carbonate, potassium bicarbonate, potassium carbonate, calcium bicarbonate, calcium bicarbonate, magnesium bicarbonate, Characterized in that it is magnesium bicarbonate or magnesium carbonate.