WO2019083211A1

WO2019083211A1 - Superabsorbent polymer preparation method

Info

Publication number: WO2019083211A1
Application number: PCT/KR2018/012127
Authority: WO
Inventors: 김무곤; 이상기; 남혜미; 이창훈; 김태윤
Original assignee: 주식회사 엘지화학
Priority date: 2017-10-27
Filing date: 2018-10-15
Publication date: 2019-05-02
Also published as: WO2019083211A9

Abstract

The present invention provides a superabsorbent polymer preparation method enabling, through a simple and economical process, preparation of a superabsorbent polymer capable of exhibiting and excellent absorption rate by comprising a uniform porous structure. The superabsorbent polymer preparation method comprises the steps of: forming a hydrogel polymer comprising a first crosslinked polymer by performing crosslinking polymerization on a water-soluble ethylenically unsaturated monomer having acidic groups of which at least a part are neutralized, in the presence of an internal crosslinking agent; drying and pulverizing the hydrogel polymer; forming a base resin powder having a diameter of 150-850 μm by classifying the pulverized polymer into polymer particles having a diameter of at least 10-150 μm, polymer particles having a diameter of 150-200 μm and polymer particles having a diameter of 200-850 μm; and surface crosslinking the base resin powder, wherein, in the crosslinking polymerization step, foaming polymerization is carried out in the presence of an anionic surfactant and the polymer particles having a diameter of 10-200 μm, which is obtained in the classification step.

Description

Title of the Invention

Method for producing superabsorbent resin

TECHNICAL FIELD

Cross-reference with related application (s)

This application claims the benefit of priority based on Korean Patent Application No. 10-2017-01451504 filed on October 27, 2017, and Korean Patent Application No. 10-2018-0121994 filed on October 12, 2018, The entire contents of which are incorporated herein by reference.

The present invention provides a method for producing a superabsorbent resin which enables production of a superabsorbent resin capable of exhibiting an excellent absorption rate including a uniform porous structure through a simple and economical process.

BACKGROUND ART [0002]

Super Absorbent Polymer (SAP) is a synthetic polymer material capable of absorbing moisture of about 500 to 1,000 times its own weight. As a result, it is possible to develop a super absorbent polymer (SAM), an absorbent gel Material). Such a superabsorbent resin has started to be put into practical use as a sanitary article, and nowadays, in addition to sanitary articles such as diapers for children, there are currently used soil repair agents for horticultural use, index materials for civil engineering and construction, sheets for seedling growing, freshness- And it is widely used as a material for fomentation and the like.

In the most cases, such superabsorbent resins are widely used in sanitary materials such as diapers and sanitary napkins. In such sanitary materials, it is general that the superabsorbent resin is contained in a state spread in the fill. In recent years, efforts have been made to provide sanitary materials such as diapers having a thinner thickness. As a part thereof, there has been proposed a so-called pulpless diaper or the like in which the content of the fill is reduced and further pulp is not used at all Development is progressing actively.

As such, in the case of sanitary materials in which the pulp content is reduced or pulp is not used, relatively high superabsorbent resins are contained in a high proportion, and these superabsorbent resin particles are inevitably contained in multiple layers in the sanitary ware. Thus, the entire superabsorbent resin particles contained in the multilayer are more efficiently mixed with liquid such as urine In order to absorb it, it is necessary that the superabsorbent resin basically exhibits high absorption performance and absorption speed.

Accordingly, in recent years, attempts have been made to manufacture and provide a superabsorbent resin exhibiting a higher absorption rate. In order to produce a superabsorbent resin exhibiting a high absorption rate as described above, it is necessary to prepare a superabsorbent resin containing a porous structure through foaming or the like. In order to introduce such a porous structure, And / or methods of applying surfactants have been used.

However, when a superabsorbent resin is produced by polymerization using a previously used blowing agent and / or surfactant, it is difficult to introduce a uniform porous structure, so that the absorption rate may not be uniformed, and the absorption rate may be very uneven And the like.

In recent years, a method of applying a special additive such as a capsule type foaming agent has been attempted. However, since the capillary type foaming agent and the like are very expensive compared to the unit cost of the superabsorbent resin itself, the economical efficiency of the whole process is low, There is a disadvantage that it becomes relatively complicated.

DETAILED DESCRIPTION OF THE INVENTION

[Technical Problem]

Accordingly, it is an object of the present invention to provide a method for producing a superabsorbent resin capable of producing a superabsorbent resin capable of exhibiting an excellent absorption rate including a uniform porous structure through a simple and economical process without using a special additive .

[Technical Solution]

According to one embodiment of the present invention, there is provided a method for producing a water-soluble ethylenically unsaturated monomer, comprising crosslinking a water-soluble ethylenically unsaturated monomer having at least partially neutralized acid groups in the presence of an internal crosslinking agent to form a hydrogel polymer comprising a first crosslinked polymer;

Drying and pulverizing the hydrogel polymer;

Contacting the ground polymer with a polymer particle having a particle size of at least 10 < RTI ID = 0.0 >

Polymer particles having a particle diameter of from 150 to 200 L and polymer particles having a particle diameter of from 200 to 850 to obtain a base resin having a particle diameter of 150 to 850 Forming a powder; And

And surface crosslinking the base resin powder,

In the cross-linking polymerization step, a method for producing a superabsorbent resin is provided in which foam polymerization is carried out in the presence of polymer particles having an average particle diameter of 10 to 200 zm obtained in the classification step and an anionic surfactant. Hereinafter, a method for producing a superabsorbent resin according to an embodiment of the present invention will be described in detail.

In the production method of the embodiment described above, the fine powder obtained in the classification step, that is, the synthetic resin particle having a particle diameter of 10 to 200 is used as a kind of foaming agent in the crosslinking polymerization for producing a superabsorbent resin, The active agent is used as a foam and a tablet. It has been confirmed that as the foaming polymerization proceeds by using such a fine powder and an anionic surface active agent, homogeneous pores are formed in the base resin powder and the superabsorbent resin obtained through the crosslinking polymerization and the subsequent steps, which are uniform in the particle diameter of the fine powder.

As described above, according to the method of one embodiment, as the superabsorbent resin having a uniform porous structure is produced as compared with the prior art using the blowing agent or the like, the superabsorbent resin can exhibit a higher absorption rate and further, The disadvantages of the conventional techniques such that the absorption rate is made nonuniform may be solved, and the superabsorbent resin particles may exhibit a uniformly uniform absorption rate as a whole.

In addition, in the method of one embodiment, the manufacturing process of the superabsorbent resin, particularly, the fine powder generally obtained in the classifying process, and the general anionic surfactant can be used without expensive additive such as capping foaming agent, Absorbing resin in which the structure is stably introduced, the process cost of the entire superabsorbent resin can be largely lowered, and a superabsorbent resin having an excellent absorption rate can be obtained through a simplified process. Hereinafter, the production method of one embodiment and the superabsorbent resin obtained thereby will be described in more detail. .

First, in the manufacturing method of this embodiment, the first crosslinked polymer The constituent water-soluble ethylenically unsaturated monomers may be any monomers conventionally used in the production of superabsorbent resins. As a non-limiting example, the water-soluble ethylenically unsaturated monomer may be a compound represented by the following Formula 1:

[Chemical Formula 1]

RrCOOM ¹

In Formula 1,

Ri is an alkyl 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. Preferably, the monomer may be at least one member selected from the group consisting of (meth) acrylic acid, and monovalent (alkali) metal salts, bivalent metal salts, ammonium pseudo and organic amine salts of these acids. When (meth) acrylic acid and / or a salt thereof is used as the water-soluble ethylenically unsaturated monomer, it is advantageous to obtain a highly water-absorbent resin having improved water absorption. Examples of the monomers include maleic anhydride, fumaric acid, crotonic acid, itaconic acid, 2-acryloylethanesulfonic acid, 2- methacryloylethanesulfonic acid, 2- (meth) acryloylpropanesulfonic acid, 2- (Meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, methoxypoly (meth) acrylate, (N, N) -dimethylaminoethyl (meth) acrylate, (N, N) -dimethylaminopropyl (meth) acrylamide, and the like can be used.

Here, the water-soluble ethylenically unsaturated 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 alkali substance such as sodium hydroxide, potassium hydroxide, ammonium hydroxide or the like.

At this time, the neutralization degree of the monomer may be 55 to 95 mol%, or 60 to 80 mol%, or 65 to 75 mol%. The degree of neutralization may vary depending on the final physical properties. However, if the degree of neutralization is too high, the neutralized monomer may precipitate and polymerization may not proceed smoothly. On the other hand, if the degree of neutralization is too low, It can exhibit properties similar to elastic rubber which is difficult to handle. In a first step of the method of the embodiment, the internal crosslinking agent and the polymer particles (fine powder) having an average particle diameter of 10 to 150 / dish obtained in the classifying process to be described later and 10 to 200 / rni, and the anionic surfactant, A monomer composition comprising a water-soluble ethylenically unsaturated monomer having at least partly neutralized acidic groups such as a < RTI ID = 0.0 >

The water-soluble ethylenically unsaturated monomer is as described above. Further, the above monomer composition, the concentration of the water-soluble ethylenically unsaturated monomer may be appropriately adjusted in consideration of the polymerization time and banung conditions, preferably from 20 to 90 parts by weight ⁰ /., Or 40 to 65 weight ⁰ /. Day . Such a concentration range may be advantageous for controlling the grinding efficiency at the time of pulverization of a polymer described below, while eliminating the need to remove the unpaired monomer after polymerization by utilizing the gel effect phenomenon occurring in the polymerization reaction of a high concentration aqueous solution. 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.

As the internal crosslinking agent, any compound can be used as long as it allows the introduction of crosslinking in the polymerization of the water-soluble ethylenically unsaturated monomer. By way of non-limiting example, the internal cross-linking agent is selected from the group consisting of N, N'-methylenebisacrylamide, trimethylol propane tri (meth) acrylate, ethylene glycol di (meth) acrylate, polyethylene glycol (meth) (Meth) acrylate, butylene diol di (meth) acrylate, butylene diol di (meth) acrylate, diethylene glycol di (meth) acrylate, ) Acrylate, triethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, dipentaerythritol pentaacrylate, glycerin tri , Pentaerythritol is reacted with tetraacrylate, triarylamine, ethylene glycol diglycidyl LE, but are propylene glycol, glycerin, or a multi-functional crosslinking agent such as ethylene carbonate may be used in combination than alone, or two, limited to no.

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.

Further, in the crosslinking polymerization step,

The polymer particles having a particle size of 150 may be contained in an amount of 0.1 to 5 parts by weight, or 0.5 to 3 parts by weight, or 0.7 to 2.5 parts by weight, based on 100 parts by weight of the monomer. Thus, it is possible to introduce a homogeneous porous structure in the base resin powder and the superabsorbent resin to cross the particle diameters of the polymer particles, that is, the fine powder, while satisfactorily proceeding the crosslinking polymerization and exhibiting a uniform and improved absorption rate The superabsorbent resin can be removed. Further, in the crosslinking polymerization step, the anionic surfactant may include sodium dodecyl sulfate, ammonium lauryl sulfate, sodium laureth sulfate, dioctyl sodium sulfosuccinate, perfluorooctanesulfonate, perfluorobutane At least one selected from the group consisting of sulfonates, alkyl-aryl ether phosphates, alkyl ether phosphates, sodium missesulfate and carboxylate salts may be used. In addition, various anionic surfactants may be used. Such anionic surfactant enables the porous structure to be better formed through the foaming polymerization using the fine powder, and stabilizes such a porous structure. Thus, by the further use of such anionic surfactant, the superabsorbent resin can exhibit a higher absorption rate.

Such anionic surfactant may be used in an amount of 0.002 to 0.05 parts by weight based on 100 parts by weight of the monomer and 0.005 to 0.02 parts by weight of black. This makes it possible to obtain a superabsorbent resin in which a uniform porous structure is suitably introduced to exhibit a further improved absorption rate while suppressing deterioration of other physical properties.

On the other hand, the monomer composition, for example, a monomer aqueous solution may contain the above-mentioned monomer, internal cross-linking agent, polymer particles having a particle diameter of 10 to 200 and anionic In addition to the surfactant, it may further comprise at least one additive selected from the group consisting of a polyvalent metal salt, a photo initiator, a thermal initiator, and a polyalkylene glycol-based polymer.

Such additives can be used to further improve the liquid permeability of the superabsorbent resin (such as polyvalent metal salt or polyalkylene glycol-based polymer), or to improve the physical properties of the superabsorbent resin by facilitating crosslinking polymerization.

The above-mentioned additives may be used in an amount of 2000 ppmw or less, 0 to 2000 ppmw, black silver or 10 to 1000 ppmw, black silver or 50 to 500 ppmw, based on 100 parts by weight of the monomer, depending on their respective roles. As a result, properties such as liquid permeability or absorption performance of the superabsorbent resin can be further improved.

Among the additives described above, polyethylene glycol, polypropylene glycol, and the like can be used as the polyalkylene glycol-based polymer.

Further, as the photo (polymerization) initiator and / or the heat (polymerization) initiator, any polymerization initiator generally used in the production of a superabsorbent resin may be used. Particularly, even in the case of the photopolymerization method, a certain amount of heat is generated by ultraviolet irradiation or the like, and a certain amount of heat is generated in accordance with the progress of the polymerization reaction, An initiator may be used together to produce a superabsorbent resin having a better absorption rate and various physical properties.

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, the persulfate-based initiator and sodium sulfate _{_{(Sodium persulfate; Na2S 2 0 8}} ), potassium persulfate _{_{(Potassium persulfate; K 2 S 2}} 0 8), ammonium persulfate _{(Ammonium persulfate; (NH 4)} 2 S 2 0 ₈ ). Azo-based initiators include 2,2-azobis (2-amidinopropane) dihydrochloride, 2,2-azobis- (N, N-dimethylene isobutyramidine dihydrochloride, 2,2-azobis- (N, N-dimethylene) isobutyramidine dihydrochloride,

(Carbamoyl azo) isobutylonitrile), 2,2-azobis [2- (2-imidazolin-2-yl) propane] diazodochloride (2,2-azobis (2-imidazolin-2-yl) propane dihydrochloride, 4,4-azobis- (4-cyanovaleric acid) cyanovaleric acid)) and the like. A wide variety of thermal polymerization initiators are described in the Odian book, " Principle of Polymerization (Wiley, 1981), " page 203, which is incorporated herein by reference.

Examples of the photo polymerization initiator include benzoin ether, dialkyl acetophenone, hydroxyl alkylketone, phenyl glyoxylate, At least one compound selected from the group consisting of benzyl dimethyl ketal, acyl phosphine and alpha-aminoketone may be used. As a specific example of the acylphosphine, a commonly used lucyrin TPO, i.e., 2,4,6-trimethyl-benzoyl-trimethyl phosphine oxide can be used . A variety of photopolymerization initiators are disclosed in Reinhold Schwalm, "UV Coatings: Basics, Recent Developments and New Applications," at page 15, page 15.

Such an initiator may be added in an amount of 500 ppmw or less based on 100 parts by weight of the monomer. 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. Conversely, if the concentration of the polymerization initiator is higher than the above range, the chain of the polymer forming the network becomes shorter, and the physical properties of the resin may be lowered, such that the content of the water-soluble component becomes higher and the pressure absorption capacity becomes lower.

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

Such a monomer composition may be prepared in the form of a solution in which a raw material such as the above-mentioned monomer is dissolved in a solvent. 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, ethane, 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, diene, xylene, butyrolactone, carbide, methylsalosolve acetate, N, N-dimethylacetamide, or a mixture thereof have.

The monomer composition having the above-mentioned form of an aqueous solution or the like can be controlled so that the initial temperature has a temperature of 30 to 60 ° C, and light energy or heat energy is applied thereto to form a crosslinking polymerization.

Formation of hydrogel polymer through cross-linking polymerization of such monomer composition can be performed 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 semi-woven machine provided with a movable conveyor belt. ^'

For example, the monomer composition may be introduced into a semipermeable vessel such as a kneader equipped with a stirring shaft _. The hydrogel polymer can be obtained by supplying hot air thereto or by heat-polymerizing the monolith. At this time, the hydrogel polymer discharged to the reactor outlet according to the shape of the stirring shaft provided in the semi-cylindrical tower can be obtained as particles of several millimeters to several centimeters. Specifically, the resulting hydrogel polymer can be obtained in various forms depending on the concentration and the injection rate of the monomer composition to be injected, and a hydrogel polymer having a particle diameter of 2 to 50 mm (weight average) can be obtained.

And, as another example, in the case of carrying out photopolymerization of the monomer composition in a semi-woven machine equipped with a movable conveyor belt, a hydrogel polymer in the form of a sheet can be obtained. At this time, the thickness of the sheet may vary depending on the concentration and the injection rate of the monomer composition to be injected. In order to ensure the uniformity of the entire sheet and to secure the production rate, the thickness of the sheet is usually adjusted to 0.5 to 5 cm desirable.

In this case usually the water content of the hydrogel polymer obtained in the same method may be 40 to 80 parts by weight ⁰ /. On the other hand, throughout the present specification, the term " moisture content " refers to the amount of moisture occupied by the total functional gel polymer weight, Quot; means the value obtained by subtracting the weight of the polymer in the state. Specifically, it is defined as a value calculated by measuring the weight loss due to moisture evaporation in the polymer in the process of raising the temperature of the polymer through infrared heating. At this time, the drying condition is a method of raising the temperature from room temperature to about 180 ^° C and then keeping it at 180 ^° C, and the total drying time is set to 20 minutes including 5 minutes of the temperature raising step, and water content is measured.

On the other hand, after the hydrogel polymer is prepared by the above-described method, the hydrogel polymer may be dried and pulverized. Prior to such drying, the step of first pulverizing the hydrous gel polymer to produce a hydrous gel polymer having a small average particle diameter may be carried out first.

In this coarsely crushing step, the hydrogel polymer can be pulverized to 1.0 mm to 2.0 mm.

The pulverizer to be used in the coarse pulverization is not limited in its constitution, but may be a vertical pulverizer, a turbo cutter, a turbo grinder, a rotary cutter mill, A crusher, a cutter mill, a disc mill, a shred crusher, a crusher, a chopper and a disc cutter. But it is not limited to the example described above.

Further, for the efficiency of the coarse pulverization, the coarse pulverization can be performed in a plurality of cycles according to the particle size. For example, the hydrogel polymer may be subjected to first crude pulverization with an average particle size of about 10 mm, second crude pulverization with an average particle diameter of about 5 mm, and then third-stage pulverization with the above-mentioned particle size.

On the other hand, after the selective coarse grinding, the hydrogel polymer can be dried. This drying temperature may be between 50 and 250 ^° C. If the drying temperature is lower than 50 ^° C, the drying time becomes excessively long and the physical properties of the ultrafine water-absorbent resin to be finally formed may deteriorate. If the drying temperature exceeds 250 ^° C, There is a possibility that the physical properties of the superabsorbent resin finally formed are lowered. More preferably, the drying can be carried out at a temperature of 150 to 200 ^° C, more preferably at a temperature of 160 to 190 ^° C. On the other hand, the drying time may be 20 minutes to 15 hours in consideration of process efficiency and the like, but is not limited thereto.

As long as it is usually used as the drying step, it can be selected and used without limitation of its constitution. Specifically, the drying step can be carried out by hot air supply, infrared irradiation, microwave irradiation, ultraviolet irradiation, or the like. The increased water content of the polymer after such drying phase, can be from 0.05 to 10 parts by weight ⁰ /.

Then, the dried polymer obtained through such a drying step

(Not shown).

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

Further, in order to control the physical properties of the superabsorbent resin powder which is finally produced after the pulverization step, a separate process of classifying the polymer powder obtained after pulverization according to the particle size may be performed.

In particular, in one embodiment, the pulverized polymer can be classified into polymer particles having a particle size of at least 10-150 / m, polymer particles having a particle size of 150-200, and polymer particles having a particle size of 200-850 have. Part of the polymer particles having a particle size of 10 to 150 / m and all of the polymer particles having a particle size of 150 to 200 are selected and the fine particles containing them are subjected to the cross- Recycle it, and use it as a kind of foaming agent. As described above, it is possible to provide a superabsorbent resin having a uniform porous structure and an improved and yet uniform absorption rate.

Further, the remaining polymer particles other than these fine particles, for example, the remainder of the polymer particles having a particle diameter of 150-200 / m, and all of the polymer particles having a particle diameter of 200-850, To form a base resin powder.

According to the classifying method of general superabsorbent resin, You can proceed using a standard sieve.

The base resin powder having such a particle diameter, that is, a particle diameter of 150 to 50 nm, can be produced through a surface cross-linking reaction step described later.

On the other hand, after proceeding to the above-described classification, the step of cross-linking the surface of the base resin powder may include a step of cross-linking the surface of the base resin powder by heat treatment of the base resin powder in the presence of a surface cross- Resin can be produced.

Here, the kind of the surface cross-linking agent contained in the surface cross-linking liquid is not particularly limited. As a non-limiting example, the surface cross-linking agent may be selected from ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol polyglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, But are not limited to, ethylene carbonate, ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, tetraethylene glycol, propanediol, dipropylene glycol, polypropylene glycol, glycerin, polyglycerin, butanediol, heptanediol, Propane, pentaerythritol, sorbic acid, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, iron hydroxide, 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 thereof, the conditions of the reaction, and preferably 0.001 to 5 parts by weight based on 100 parts by weight of the base resin powder. If the content of the surface cross-linking agent is too low, surface cross-linking may not be properly introduced, and the physical properties of the final superabsorbent resin may be deteriorated. On the contrary, if the surface cross-linking agent is used in an excessive amount, absorption of the superabsorbent resin may be lowered due to excessive surface cross-linking reaction, which is not preferable.

The surface cross-linking solution may be 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, Methylene chloride, methyl ethyl ketone, acetone, methyl amyl ketone, cyclohexanone, cyclopentanone, diethylene glycol monomethyl ether, diethylene glycol ethyl ether, Butylolactone, carboxy, methylcellosolve acetate, and N, N-dimethylacetamide. The solvent may be included in an amount of 0.5 to 10 parts by weight based on 100 parts by weight of the base resin.

Further, the surface cross-linking solution may further include a thickener. If the surface of the base resin powder is further crosslinked in the presence of the thickening agent, deterioration of physical properties can be minimized even after the pulverization. Specifically, as the thickening agent, at least one selected from a polysaccharide and a hydroxy-containing polymer may be used. The polysaccharide may be a gum-based thickener, a salicylose-based thickener, or the like. Specific examples of the gum series thickener include xanthan gum, arabic gum, karaya gum, tragacanth gum, ghatti gum, guar gum, guar gum, locust bean gum, and psyllium seed gum. Examples of the cellulose-based thickener include hydroxypropyl methylcellulose, carboxymethyl cellulose, Cellulose, methyl salicylose,. Hydroxymethylcellulose, hydroxypropylmethylcellulose, hydroxypropylmethylcellulose, hydroxypropylmethylcellulose, hydroxypropylmethylcellulose, hydroxypropylmethylcellulose, hydroxypropylmethylcellulose, hydroxypropylmethylcellulose, hydroxypropylmethylcellulose, hydroxypropylmethylcellulose, Ethylcellulose, and methylhydroxypropylcellulose, and the like. On the other hand, specific examples of the hydroxy-containing polymer include polyethylene glycol and polyvinyl alcohol.

In order to perform the surface cross-linking, a method of mixing the surface cross-linking liquid and the base resin in a reaction vessel, a method of spraying a surface cross-linking solution onto the base resin, A method in which the liquid is continuously supplied and mixed, or the like can be used.

The surface cross-linking may be carried out at a temperature of 100 to 250 ^° C, and may be continuously performed after the drying and crushing step which proceeds at a relatively high temperature. At this time. The surface cross-linking reaction may be carried out for 1 to 120 minutes, or 1 to 100 minutes, or 10 to 60 minutes. That is, the surface cross-linking reaction may be carried out in order to prevent the degradation of the physical properties of the polymer particles during the excessive migration while inducing the minimum surface cross-linking reaction. The superabsorbent resin prepared as described above can have a bulk density of 0.55 to 0.65 g / ml, or 0.57 to 0.64 g / ml, as a uniform porous structure is introduced. The absorption rate measured according to the Vortex measurement method may be 30 to 53 seconds, or 33 to 50 seconds, or 35 to 48 seconds. The absorption rate refers to the time for which the vortex of the liquid disappears due to rapid absorption when the superabsorbent resin is added to the physiological saline solution and stirred. This means a rapid absorption capacity of the superabsorbent resin. The concrete measurement method thereof will be further specified in the following examples.

The superabsorbent resin has a centrifugal separation capacity (CRC) of 28 to 35 g / g or 30 to 33 g / g measured according to the EDANA method WSP 241.3 and a pore volume of 0.9 psi measured according to EDANA method WSP 242.3 And a pressure absorption capacity (AUL) of 16 to 23 g / g, or 17 to 20 g / g. As described above, the superabsorbent resin exhibits an improved absorption rate as described above, and can maintain excellent absorption ability / pressure absorption ability.

Also preferably, the superabsorbent resin has an average particle diameter of 300 to 600. Also preferably includes a super-absorbent resin and the particle diameter of the water-absorbent resin is 300 to 600 m according to the invention to 45 to 85 parts by weight ⁰ /. Further, preferably, a superabsorbent resin having a particle size of 300 or less in the superabsorbent resin

15 comprises by weight ⁰ /. Above.

【Effects of the Invention】

INDUSTRIAL APPLICABILITY As described above, according to the present invention, it is possible to provide a superabsorbent resin composition which has a uniform porous structure and exhibits a uniform and evenly absorbing rate as a whole through a simple and economical process that does not use a special additive such as a capsule- &Lt; / RTI >

DETAILED DESCRIPTION OF THE INVENTION

Best Mode for Carrying Out the Invention Hereinafter, preferred embodiments are shown to facilitate understanding of the present invention. However, the following examples are intended to illustrate the present invention without limiting it thereto. Example 1 (Step 1)

(Solution A) in which 9 g of IRGACURE 819 initiator diluted to 0.5% in acrylic acid (80 ppmw for the monomer composition) and 40 g of polyethylene glycol diacrylate (PEGDA, Mw = 400) encapsulated in acrylic acid at 5% .

490 g of acrylic acid and the solution A were injected into a 2L capacity glass-sealed vessel surrounded by a jacket in which a heating medium precooled at 25 ^° C was circulated. Then, 850 g of a 24% caustic soda solution (C solution) was gradually added dropwise to the above-described glass semi-frozen period. After confirming that the temperature of the common liquid was raised to about 72 ^° C by the neutralizing heat, it waited until the fugitive solution was stirred. The degree of acidification of acrylic acid in the obtained solution was about 70 mol%. 5 g (1 wt% based on acrylic acid) of the fine powder (polymer particles of the base resin powder having a particle size of 10 to 150) obtained in the step 3 described later was added to the monomer aqueous solution. In addition, 5 g (170 ppmw) of a solution of sodium dodecylsulfate (D-1 solution), which was encapsulated in water at 2%, was prepared as a surfactant. Further, 30 g of a sodium persulfate solution (D-2 solution) diluted with water to 4% was prepared. Then, when the silver solution of the fused solution was cooled to about 45 ^° C, D-1 and D-2 solutions previously prepared were injected into the fused solution and fused.

(Step 2)

Subsequently, the fountain solution prepared in Step 1 was poured into a Vat-shaped tray (15 cm x 15 cm wide) equipped with a light irradiation device on the top and a square polymerizer whose interior was preheated to 8 C C. Thereafter, the mixed solution was irradiated with light. It was confirmed that the gel was formed from the surface after about 20 seconds from the light irradiation point, and it was confirmed that polymerization reaction occurred simultaneously with foaming after about 30 seconds from the light irradiation point. Then, continue the polymerization for an additional 2 minutes. And the polymerized sheet was taken out and cut into a size of 3 cm x 3 cm. Then, the cut sheet was made into a crump by chopping using a meat chopper. The average particle size of the crump produced was 1.5 mm.

(Step 3) Then, the crump prepared in the above step 2 was dried in an oven capable of controlling the airflow in the up and down directions. The hot air of 18CTC was allowed to flow upward from below for 15 minutes and then flow downward from above for 15 minutes to make the crump uniform so that the water content of the dried powder was less than about 2% Lt; / RTI > The dried powder was pulverized by a pulverizer and classified to obtain a base resin having a size of 150 to 850 IM. The remaining polymer particles of the base resin powder having a particle diameter of 10 to 150 / were used by recycling to the above-mentioned step 1.

(Step 4)

Then, 4 g of water, 1 g of ethylene carbonate and 0.1 g of Aerosil 200 (Aerosil 200, Evonik) were mixed with 100 g of the base resin prepared in the above step 3, and then the mixture was kneaded at 190 ° C for 30 minutes While the surface bridging reaction was allowed. Then, the obtained product was pulverized and a superabsorbent resin having a surface cross-linked particle diameter of 150 to 850 를 was obtained by using a sieve. 0.1 g of Aerosil 200 was dry-added to the obtained superabsorbent resin and mixed in a dry state to prepare a superabsorbent resin. Example 2

(Step 1)

(Solution A) of 40 g of polyethylene glycol diacrylate (PEGDA, Mw = 400) diluted to 5% in acrylic acid with 9 g of an IRGACURE 819 initiator diluted to 0.5% in acrylic acid (80 ppmw with respect to the monomer composition) .

490 g of acrylic acid and the solution A were injected into a 2L capacity glass-sealed vessel surrounded by a jacket in which a heating medium precooled at 25 ^° C was circulated. Then, 850 g of a 24% caustic soda solution (C solution) was gradually added dropwise to the above-described glass semi-frozen period. After confirming that the silver of the common stock was elevated to about 72 ^° C by the heat of neutralization, we waited for the stock solution to cool down. The degree of neutralization of acrylic acid in the obtained solution was about 70 mol%. It was added a fine powder 15g (acrylic acid from the third weight ⁰ /.) Of (10 to base polymer resin powder particles having a particle diameter of 150βη) obtained in step 3 to be described later in the aqueous monomer solution. As a surfactant, sodium dodecylsulfate solution (D-1) diluted with water to 2% 5 g (170 ppmw) was prepared. Further, 30 g of a sodium persulfate solution (D-2 solution), which was 4% in water, was prepared. Then, when the temperature of the fugitive solution was reduced to about 45 ^° C, the previously prepared D-1 and D-2 solutions were injected into the fugitive solution and fused. .

Thereafter, steps 2 to 4 were carried out in the same manner as in Example 1 to prepare a superabsorbent resin. Example 3

(Step 1)

490 g of acrylic acid and the solution A were injected into a 2 L capacity glass reactor surrounded by a jacket in which a heating medium precooled at 25 ^° C was circulated. Then, 850 g of a 24% caustic soda solution (C solution) was gradually added dropwise to the above-described glass semi-frozen period. After confirming that the temperature of the common liquid was raised to about 72 ^° C by the neutralizing heat, it waited until the fugitive solution was stirred. The degree of neutralization of acrylic acid in the obtained solution was about 70 mol%. A fine powder 25g (acrylic acid over 5 parts by weight ⁰ /. Of the polymer particles of the base resin powder having a particle size of 10 to 150 ^) obtained in Step 3 described below was added to the aqueous monomer solution. 5 g (170 ppmw) of sodium dodecylsulfate solution (D-1 solution) diluted with water to 2% was prepared as a surfactant. Further, 30 g of a sodium persulfate solution (D-2 solution) diluted with water to 4% was prepared. When the temperature of the fusing solution was cooled to about 45 ^° C, D-1 and D-2 solutions previously prepared were injected into the fusing solution and fused.

Thereafter, steps 2 to 4 were carried out in the same manner as in Example 1 to prepare a superabsorbent polymer. Comparative Example 1 (Step 1)

490 g of acrylic acid and the above solution A were injected into a 2L capacity glass semi-sealed vessel surrounded by a jacket circulating a heating medium preliminarily angled at 25 ^° C. Then, 850 g of a 24% caustic soda solution (C solution) was gradually added dropwise to the above-described glass semi-frozen period. After confirming that the temperature of the common liquid was raised to about 72 ^° C by the neutralizing heat, it waited until the fugitive solution was stirred. The degree of neutralization of acrylic acid in the obtained solution was about 70 mol%. 5 g (170 ppmw) of sodium dodecylsulfate solution (D-1 solution) diluted with water to 2% was prepared as a surfactant. Further, 30 g of a sodium persulfate solution (D-2 solution) diluted with water to 4% was prepared. Then, when the temperature of the fugitive solution was reduced to about 45 ^° C, the previously prepared D-1 and D-2 solutions were injected into the fugitive solution and fused. And it was prepared by the SBC heunhap solution to 4 parts by weight ⁰ / concentration by injecting about 6.25g (500 ppm with respect to the monomer composition) in the solution heunhap

Thereafter, steps 2 to 4 were carried out in the same manner as in Example 1 to prepare a superabsorbent resin. Comparative Example 2

A superabsorbent resin was prepared in the same manner as in Example 1 except that sodium dodecylsulfate solution (D-1 solution) was not used in step 1. Comparative Example 3

In step 1, a superabsorbent resin was prepared in the same manner as in Example 2, except that sodium dodecylsulfate solution (D-1 solution) was not used. Experimental Example: Evaluation of Physical Properties of Gohubu Water Resin

The physical properties of the superabsorbent resin prepared in the above Examples and Comparative Examples were evaluated by the following methods, and the results are shown in Table 1. (1) Bulk density:

About 100 g of the superabsorbent resin was placed in a bulk density measuring instrument in the form of a funnel, and the weight of the superabsorbent resin contained in the vessel was measured. The bulk density was calculated as (superabsorbent resin weight) / (vessel volume, 100 ml). (Unit: g / ml).

(2) Vortex time

The absorption rates of the superabsorbent resins of Examples and Comparative Examples were measured in seconds in accordance with the method described in International Patent Publication No. 987-003208.

Specifically, the absorption rate (black vortex time) was determined by adding 2 g of superabsorbent resin to 50 ml_ of physiological saline at 23 ^° C to 24 ^° C and changing the magnetic bar (diameter 8 mm, length 31.8 mm) to 600 rpm And the time until the disappearance of the vortex by stirring was calculated in seconds.

(3) Centrifuge Retention Capacity (CRC) The retention capacity of each resin under loadless capacity was measured according to EDANA WSP 241.3.

Specifically, in the resin obtained through each of the examples and comparative examples, a resin classified with a sieve of # 30-50 was obtained. This resin W ₀ (g) (about 0.2 g) was uniformly put into an envelope made of a nonwoven fabric and sealed, and then immersed in physiological saline (0.9 wt%) in the upper atmosphere. After 30 minutes, water was drained from the envelope for 3 minutes under a condition of 250 G using a centrifuge, and the mass W ₂ (g) of the envelope was measured. In addition, after the same operation was performed without using a resin, the mass W (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) = {[W ₂ (g) - W, (g)] / W ₀ (g)

(4) Absorption under load (AUL)

The pressure absorption capacity of 9 psi of each resin was measured according to EDANA method WSP 242.3.

First, at the time of measuring the adsorption capacity, a resin classifier at the time of CRC measurement was used.

Specifically, a 400 mesh wire mesh made of stainless steel was attached to the bottom of a cylindrical plastic having an inner diameter of 25 mm. The piston capable of uniformly spreading the water absorbent resin W ₀ (g) (0.16 g) on the wire net under uniform temperature and humidity of 50% and uniformly applying a load of 0.9 psi thereon is slightly smaller than the outer diameter of 25 mm The inner wall of the cylinder is free from cracks and the up and down movement is prevented from being disturbed. At this time, the weight W ₃ (g) of the device was measured.

A glass filter having a diameter of 90 mm and a thickness of 5 mm was placed inside a Petro dish having a diameter of 150 mm and a physiological saline solution composed of 0.9% 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 a filter paper, and the solution was absorbed under a load for 1 hour. After one hour, the measuring device was lifted and its weight W ₄ (g) was measured. The pressure absorption capacity (g / g) was calculated by using the obtained masses according to the following equation.

&Quot; (2) "

AUL (g / g) = [ W 4 (g) - W 3 (g)] / W 0 (g) shows the measurement results are shown below in Table 1 as described above.

Claims

Claims:

[Claim 1]

Crosslinking a water-soluble ethylenically unsaturated monomer having at least partially neutralized acidic groups in the presence of an internal crosslinking agent to form a hydrogel polymer comprising the first crosslinked polymer;

Drying and pulverizing the hydrogel polymer;

The pulverized polymer is classified into polymer particles having a particle diameter of at least 10 to 150, polymer particles having a particle diameter of 150 to 200 beta eta, and polymer particles having a particle diameter of 200 to 850 to obtain a base resin powder having a particle diameter of 150 to 850 / ; And

And surface crosslinking the base resin powder,

In the crosslinking polymerization step, the foaming polymerization is carried out in the presence of the polymer particles having a particle diameter of 10 to 200 and the anionic surfactant obtained in the classification step.

[Claim 2]

Method, the monomers are (meth) art reel acid process for producing a superabsorbent resin having a degree of neutralization of the neutralized part of the (meth) acrylic acid and alkali metal salts include, and 55 to 95 mole ⁰ / thereof. The method of claim 1.

[Claim 3]

The method according to claim 1, wherein in the crosslinking polymerization step, the polymer particles having a particle diameter of 10 to 200 are used in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the monomer.

Claim 4

The composition of claim 1 wherein the anionic surfactant is selected from the group consisting of sodium dodecyl sulfate, ammonium lauryl sulfate, sodium laureth sulfate, dioctyl sodium sulfosuccinate, perfluorooctanesulfonate, perfluorobutanesulfonate, alkyl - aryl ether phosphates, alkyl ether phosphates, sodium misses Sulfates, and carboxylate salts of at least one member selected from the group consisting of water,

[Claim 5]

The method according to claim 1, wherein in the crosslinking polymerization step, the anionic surfactant is used in an amount of 0.002 to 0.05 part by weight based on 100 parts by weight of the monomer.

[Claim 6]

The method of claim 1, wherein in the cross-linking polymerization step, the monomer, internal crosslinking agent, wherein the 10 to polymer particles having a particle diameter of 200 and an anionic monomer aqueous solution containing a surfactant is used, the aqueous solution is from 30 to 60 ^° C By weight based on the total weight of the resin.

7.

The method according to claim 6, wherein the aqueous monomer solution further comprises at least one additive selected from the group consisting of a polyvalent metal salt, a photoinitiator, a thermal initiator, and a polyalkylene glycol-based polymer.

8.

8. The method according to claim 7, wherein the additive is used in an amount of 2000 ppmw or less based on 100 parts by weight of the monomer.

[Claim 9]

The absorbent article as claimed in claim 1, wherein the superabsorbent resin has a bulk density of 0.55 -

0.65 g / ml, and the absorption rate measured according to the Vortex measurement method is 30 seconds to 53 seconds.

[Claim 10]

The method according to claim 1, wherein the superabsorbent resin is prepared according to EDANA method WSP 241.3 Centrifuge beam SAT (CRC) is 28 to 35 g / g and, EDANA Method pressure of 0.9 psi measured according to WSP 242.3 absorption capacity (AUL) is 16 to 23 g / g of super-absorbent ^"production method of the resin measured.