KR20160030711A

KR20160030711A - Polymerization reactor for super adsorbent polymer and preparation method for super absorbent polymer

Info

Publication number: KR20160030711A
Application number: KR1020140120231A
Authority: KR
Inventors: 유철희; 김기철
Original assignee: 주식회사 엘지화학
Priority date: 2014-09-11
Filing date: 2014-09-11
Publication date: 2016-03-21
Also published as: WO2016039547A1

Abstract

The present invention relates to a polymerization reactor for producing a superabsorbent resin and a method for producing a superabsorbent resin using the same. The polymerization reactor for producing a superabsorbent resin of the present invention comprises a monomer composition supply unit for supplying a monomer composition comprising a water-soluble ethylenically unsaturated monomer, a polymerization initiator and a solvent; And a reaction part connected to the monomer composition supplying part and including a light irradiating part for supplying light to the monomer composition, wherein the light irradiating part includes first to third light irradiation areas in order along the length direction of the reaction part And Q3 > Q1 > Q2 when the light amounts of the first to third light irradiation regions are Q1 to Q3, respectively. According to the present invention, it is possible to make the polymerization rate of the monomer composition uniform, to make the cross-linking density uniform, and to produce a superabsorbent resin with improved physical properties.

Description

TECHNICAL FIELD [0001] The present invention relates to a polymerization reactor for producing a superabsorbent resin, and a method for producing a superabsorbent resin using the polymerizable monomer.

The present invention relates to a polymerization reactor for producing a superabsorbent resin and a method for producing a superabsorbent resin using the same. More specifically, the present invention relates to a polymerization reactor for producing a superabsorbent resin comprising a plurality of irradiated regions having different amounts of light, and a method for producing a superabsorbent resin using the same.

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), and so on. 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.

The above-mentioned superabsorbent resin can be generally produced by polymerizing a monomer for a resin, drying and pulverizing it to obtain a powdery product.

The step of polymerizing the monomer during the step of producing such a superabsorbent resin is an important step for determining the physical properties of the resin. As such polymerization methods, there are known methods such as reversed-phase suspension polymerization, thermal polymerization and photopolymerization. As a method of photopolymerization, there is a method in which a monomer composition for a resin is placed on a belt and light is irradiated from above to polymerize the monomer composition.

However, when the polymerization is carried out as described above, the irradiation dose is not constant depending on the depth of the monomer composition and the polymerization reaction time, and the degree of polymerization may be uneven depending on the position.

That is, there is a difference in the polymerization reaction speed between the sections as the polymerization reaction progresses as the belt on which the monomer composition is placed moves. In a conventional polymerization reactor, light irradiation is performed at a constant light amount regardless of the reaction speed. As a result, the polymerization proceeds excessively at a high polymerization speed, and at a relatively low polymerization speed, the amount of light irradiation is relatively insufficient, so that the polymerization may not be completed and the unpolymerized components may remain. In this case, the cross-linking density of the monomer composition is not constant and the physical properties of the superabsorbent resin may be deteriorated.

In order to solve this problem, it is possible to adjust the moving speed of the monomer composition or to vary the light irradiation time, but in this case, the process becomes complicated and the process time is increased and the productivity may be lowered.

In order to solve the problems of the prior art as described above, the present invention provides a method of producing a superabsorbent resin capable of exhibiting a uniform polymerization reaction rate by using a polymerization reactor for producing a superabsorbent resin including a plurality of irradiated regions having different amounts of light And to provide the above objects.

According to an aspect of the present invention,

A monomer composition supplier for supplying a monomer composition comprising a water-soluble ethylenically unsaturated monomer, a polymerization initiator and a solvent; And a reaction part connected to the monomer composition supplying part and including a light irradiating part for supplying light to the monomer composition, wherein the light irradiating part includes first to third light irradiation areas in order along the length direction of the reaction part And Q3 > Q1 > Q2, wherein the amounts of light of the first to third light irradiation regions are Q1 to Q3, respectively.

According to another aspect of the present invention, there is provided a process for preparing a polymer composition, comprising: preparing a monomer composition comprising a water-soluble ethylenically unsaturated monomer, a polymerization initiator, and a solvent; And polymerizing the monomer composition using the polymerization reactor.

According to the polymerization reactor for producing a superabsorbent resin and the method for producing a superabsorbent resin using the same according to the present invention, it is possible to produce a superabsorbent resin having a uniform polymerization rate and uniformity of crosslinking density of the monomer composition, thereby improving physical properties.

1 is a view showing a polymerization reactor for producing a superabsorbent resin according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Hereinafter, with reference to the drawings, a polymerization reactor for preparing a superabsorbent resin according to an embodiment of the present invention and a method for producing a superabsorbent resin using the same will be described in detail.

A polymerization reactor for preparing a superabsorbent resin according to an aspect of the present invention comprises a monomer composition supply unit for supplying a monomer composition comprising a water-soluble ethylenically unsaturated monomer, a polymerization initiator and a solvent; And a reaction part connected to the monomer composition supplying part and including a light irradiating part for supplying light to the monomer composition, wherein the light irradiating part includes first to third light irradiation areas in order along the length direction of the reaction part And Q3 > Q1 > Q2 when the light amounts of the first to third light irradiation regions are Q1 to Q3, respectively.

1 shows a polymerization reactor for producing a superabsorbent resin according to an embodiment of the present invention.

Referring to FIG. 1, the polymerization reactor 100 of the present invention comprises a monomer composition supply unit 50 for supplying a monomer composition comprising a water-soluble ethylenically unsaturated monomer, a polymerization initiator and a solvent; And a light irradiation unit (60) connected to the monomer composition supply unit (50) and supplying light to the monomer composition; And a reaction part 80 including an aging area 65. The light irradiation part 60 includes a plurality of light irradiation areas 60a, 60b, and 60c having different amounts of light.

According to one embodiment of the present invention, the monomer composition supply unit 50 includes a raw material supply unit 10, 20, 30 for supplying a water-soluble ethylenically unsaturated monomer, a polymerization initiator, etc. as a raw material of a superabsorbent resin, And a solvent supply unit 40 for supplying the solvent. The monomer composition containing the raw material and the solvent transferred from the raw material supplying portions 10, 20 and 30 and the solvent supplying portion 40 is transferred to the reaction portion 80 through the monomer composition supplying portion 50.

The raw material for the superabsorbent resin may be, for example, a water-soluble ethylenically unsaturated monomer, a basic compound for neutralization of the monomer, a polymerization initiator, a crosslinking agent and various additives, and the solvent is not limited as long as it is a liquid capable of dissolving the raw material. Although the raw material supply units 10, 20 and 30 are shown as three in the figure, the present invention is not limited thereto and can be variously modified depending on the kind and number of raw materials. In addition, although the solvent is separately supplied through the solvent supply unit 40, the present invention is not limited thereto, and can be variously modified.

The reaction unit 80 includes a conveyor belt 70 for carrying out the polymerization reaction while moving the monomer composition and a light irradiation unit 60 for supplying light energy required for monomer polymerization.

The monomer composition supplied to the reaction part 80 moves from one end to the other end of the conveyor belt 70 as the conveyor belt 70 moves. In this way, during the movement, the monomer composition proceeds through the crosslinking polymerization reaction by the light supplied from the light irradiation part 60 of the reaction part 80, that is, UV.

The light irradiation unit 60 includes a plurality of light irradiation regions 60a, 60b, and 60c having different amounts of light. 1, the present invention is not limited to this. However, the present invention is not limited thereto, and if at least two or more light irradiation regions are provided and the light amount of the light irradiation region is different, .

The first light irradiation region 60a, the second light irradiation region 60b, and the third light irradiation region 60c (not shown) are formed along the longitudinal direction of the reaction part 80. The first light irradiation area 60a, the second light irradiation area 60b, ).

The polymerization reactor according to an embodiment of the present invention is characterized in that it includes a plurality of irradiated regions having different amounts of light as described above. In the case of a polymerization reactor in which the monomer composition is supplied with light energy and a polymerization reaction takes place while the conveyor belt supplied with the monomer composition moves, there is a difference in polymerization reaction speed between the sections. For example, although the polymerization rate is low at the beginning of the reaction, that is, at the front end portion of the reactor, the temperature of the monomer composition gradually increases as the polymerization reaction, which is an exothermic reaction, proceeds to a high temperature state. Therefore, the reaction rate becomes faster at the middle portion of the reaction, that is, at the reactor stop portion. In addition, unreacted monomers are reduced in the latter half of the reaction and the reaction rate is again slowed down.

As described above, the reaction rate of the monomer composition varies depending on the section, but in a conventional polymerization reactor, light irradiation is performed at a constant amount of light irrespective of the reaction rate. As a result, the polymerization proceeds excessively at a high polymerization speed, and at a relatively low polymerization speed, the amount of light irradiation is relatively insufficient, so that the polymerization may not be completed and the unpolymerized components may remain. In this case, the cross-linking density of the monomer composition is not constant, resulting in deterioration of the physical properties of the superabsorbent resin.

However, the light irradiation portion of the polymerization reactor of the present invention has a plurality of light irradiation regions, and the light amounts of the plurality of light irradiation regions are made different according to the reaction rate or the reaction region, and as a result, The speed can be made constant. Accordingly, the cross-linking density of the monomer composition becomes uniform, and the physical properties of the ultrafine water-absorbent resin finally produced can be improved.

According to an embodiment of the present invention, when the amounts of light of the first to third light irradiation regions 60a, 60b, and 60c are respectively Q1 to Q3, a relationship of Q3 > Q1 > Q2 may be established. For example, when Q1 is 100%, Q3 may have a light amount of about 100 to about 140%, or about 100 to about 120%, and Q2 may have a light amount of about 40 to about 80%, or about 40 To about 60%. The Q1 may also be about 6 to about 12 mW, or about 8 to about 12 mW.

The area occupied by each of the first to third light irradiation regions 60a, 60b, and 60c is not particularly limited. However, when the total area of the light irradiation portions 60 is assumed to be 100% The irradiation areas 60a, 60b and 60c can be set in such a manner that the total area of the irradiation part 60 is divided into about 20 to about 30%: about 40 to about 70%: about 10 to about 30%.

The time for performing the light irradiation in the first to third light irradiation regions 60a, 60b, and 60c is set to be shorter than the first to third light irradiation regions 60a and 60b , About 60% to about 70%: about 10% to about 30%, respectively.

The light source that can be provided in the light irradiation region is not particularly limited, and an ultraviolet light source known to be capable of causing a photopolymerization reaction to the monomer composition may be used without limitation. For example, light having a wavelength of about 200 to about 400 nm may be used, and an ultraviolet light source such as a Xe lamp, a mercury lamp, or a metal halide lamp may be used. Further, the arrangement of the light sources can be arbitrarily adjusted, such as parallel to, perpendicular to, or intersecting with the traveling direction of the monomer composition, and is not particularly limited.

In the aging zone 65, the natural gelation is progressed until the hydrogel polymer which has been polymerized in the light irradiation unit 60 goes to the coarsely crushing stage, and may be selectively or not included.

A hydrogel polymer on a sheet can be obtained by such a process. The coalescer gel polymer on the polymerized sheet is discharged through the discharge portion 90, and further coarsely pulverized in the connected crushing portion. On the other hand, the structure of the pulverizing section is not limited as long as it includes a pulverizer capable of pulverizing the co-aggregate gel polymer on the sheet.

More specifically, a vertical milling machine such as a vertical pulverizer, a turbo cutter, a turbo grinder, a rotary cutter mill, a cutter mill, a disc mill A crusher, a shred crusher, a crusher, a chopper, and a disk cutter, but the present invention is not limited to the above example .

In this case, the coarse pulverization step may be performed such that the particle size of the co-gel polymer is about 2 to about 10 mm.

The coarse aggregate gel polymer may be dried to a water content of about 1 to about 5% and then ground to a particle size of about 150 to about 850 [mu] m.

The drying method in the drying step may also be selected and used without limitation in the constitution as long as it is usually used as a drying step of the hydrous gel polymer. Specifically, the drying step can be carried out by hot air supply, infrared irradiation, microwave irradiation, ultraviolet irradiation, or the like. The water content of the polymer after such a drying step may be from about 0.1 to about 10% by weight.

The pulverizer used for crushing the dried polymer is specifically 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, a separate process of classifying the polymer obtained after the pulverization according to the particle size can be performed. Preferably, the polymer having a particle size of about 150 to about 850 탆 can be classified.

According to another aspect of the present invention, there is provided a process for preparing a superabsorbent resin comprising the steps of: preparing a monomer composition comprising a water-soluble ethylenically unsaturated monomer, a polymerization initiator, and a solvent; And polymerizing the monomer composition using the polymerization reactor.

The monomer composition which is a raw material of the superabsorbent resin includes a water-soluble ethylenically unsaturated monomer and a polymerization initiator.

The water-soluble ethylenically unsaturated monomer may be any monomer conventionally used in the production of a superabsorbent resin without any particular limitations. Here, at least one monomer selected from the group consisting of an anionic monomer and its salt, a nonionic hydrophilic-containing monomer and an amino group-containing unsaturated monomer and a quaternary car- bon thereof may be used.

Specific examples include (meth) acrylic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, 2- acryloylethanesulfonic acid, 2- methacryloylethanesulfonic acid, 2- (meth) acryloylpropanesulfonic acid, 2- Metha) acrylamide-2-methylpropanesulfonic acid and salts thereof; (Meth) acrylamide, N-substituted (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate or polyethylene glycol Non-ionic hydrophilic-containing monomer of (meth) acrylate; And at least one selected from the group consisting of unsaturated monomers containing an amino group of (N, N) -dimethylaminoethyl (meth) acrylate or (N, N) -dimethylaminopropyl (meth) .

More preferably, acrylic acid or a salt thereof, for example, an alkali metal salt such as acrylic acid or sodium salt thereof can be used. By using such a monomer, it becomes possible to produce a superabsorbent resin having superior physical properties. When the alkali metal salt of acrylic acid is used as a monomer, acrylic acid may be neutralized with a basic compound such as sodium hydroxide (NaOH).

The concentration of the water-soluble ethylenically unsaturated monomer may be about 20 to about 60% by weight, preferably about 40 to about 50% by weight, based on the monomer composition including the raw material and the solvent of the superabsorbent resin, It may be an appropriate concentration considering time and reaction conditions. However, if the concentration of the monomer is excessively low, the yield of the superabsorbent resin may be low and economical efficiency may be deteriorated. On the other hand, if the concentration is excessively high, a part of the monomer may precipitate or the pulverization efficiency may be low Problems such as the like may occur and the physical properties of the superabsorbent resin may be deteriorated.

The photopolymerization initiator can be used without limitation in the constitution as long as it is a compound capable of forming a radical by light such as ultraviolet rays.

Examples of the photopolymerization initiator include benzoin ether, dialkyl acetophenone, hydroxyl alkylketone, phenyl glyoxylate, benzyl dimethyl ketal Ketal, acyl phosphine, and alpha-aminoketone may be used. On the other hand, 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 . More photoinitiators are well described in Reinhold Schwalm, "UV Coatings: Basics, Recent Developments and New Applications (Elsevier 2007) " p. 115, and are not limited to the above examples.

The photopolymerization initiator may be included in the monomer composition at a concentration of about 0.002% to about 0.2% by weight. If the concentration of such a photopolymerization initiator is too low, the polymerization rate may be slowed. If the concentration of the photopolymerization initiator is too high, the molecular weight of the superabsorbent resin may be small and the physical properties may become uneven.

According to an embodiment of the present invention, the monomer composition may further include an internal cross-linking agent as a raw material of the superabsorbent resin. As the internal crosslinking agent, a crosslinking agent having at least one functional group capable of reacting with the water-soluble substituent of the water-soluble ethylenically unsaturated monomer and having at least one ethylenic unsaturated group; Or a crosslinking agent having two or more functional groups capable of reacting with water-soluble substituents formed by hydrolysis of the water-soluble substituents and / or monomers of the monomers.

Specific examples of the internal crosslinking agent include bisacrylamide having 8 to 12 carbon atoms, bismethacrylamide, poly (meth) acrylate of polyol having 2 to 10 carbon atoms or poly (meth) allyl ether of polyol having 2 to 10 carbon atoms (Meth) acrylate, ethyleneoxy (meth) acrylate, propyleneoxy (meth) acrylate, glycerin diacrylate, At least one selected from the group consisting of glycerin triacrylate, trimethylol triacrylate, triallylamine, triaryl cyanurate, triallyl isocyanate, polyethylene glycol, diethylene glycol and propylene glycol can be used.

Such an internal crosslinking agent may be included at a concentration of about 0.01 to about 0.5% by weight based on the monomer composition to crosslink the polymerized polymer.

In the production method of the present invention, the monomer composition of the superabsorbent resin may further contain additives such as a thickener, a plasticizer, a storage stabilizer, and an antioxidant, if necessary.

The raw materials such as the above-mentioned water-soluble ethylenically unsaturated monomers, photopolymerization initiators, internal cross-linking agents and additives can be prepared in the form of a monomer composition solution dissolved in a solvent.

The solvent which can be used at this time can be used without limitation of its constitution as long as it can dissolve the above-mentioned components. Examples thereof include water, ethanol, ethylene glycol, diethylene glycol, triethylene glycol, Propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, methyl ethyl ketone, acetone, methyl amyl ketone, cyclohexanone, cyclopentanone, diethylene glycol monomethyl ether, diethylene glycol At least one selected from ethyl ether, toluene, xylene, butylolactone, carbitol, methylcellosolve acetate and N, N-dimethylacetamide can be used in combination.

The solvent may be included in the remaining amount of the monomer composition excluding the components described above.

In the method for producing a superabsorbent resin of the present invention, the monomer composition is polymerized using the polymerization reactor described above.

That is, the relationship between Q3 = Q1 > Q2 and Q3 = Q1 > Q2 when the amounts of light of the first through third light irradiation regions are respectively Q1 through Q3 are sequentially included along the longitudinal direction of the reaction portion A monomer composition containing a water-soluble ethylenically unsaturated monomer, a polymerization initiator, and a solvent is supplied to a reactor equipped with a light irradiating unit satisfactory to obtain a hydrogel polymer.

A more detailed description of the polymerization reactor is as described above.

The size of the resulting hydrogel polymer may vary depending on the concentration of the monomer composition to be injected, the rate of injection, etc. Usually, a hydrogel polymer having a weight average particle diameter of 2 to 50 mm can be obtained.

By performing the polymerization reaction by the above-mentioned method, the superabsorbent resin produced according to the present invention has a high centrifugal support capacity and a low water solubility in comparison with the case of using a conventional polymerization reactor having a light irradiating unit having a uniform light quantity Component content, and can achieve uniform crosslink density. For example, the superabsorbent resin prepared in accordance with the present invention has a solubility of about 38 g / g or more, preferably about 39 g / g or more, more preferably about 42 g / g or more, g / g centrifugal support capacity (CRC). In addition, a water content of less than or equal to about 15 wt%, preferably less than or equal to about 14 wt%, and more preferably less than or equal to about 13 wt% At this time, the centrifuge support capacity is measured by EDANA (European Disposables and Nonwovens Association) Test Method 441.2-02, and the water soluble component may be the value measured by EDANA Test Method 270.2.

The base polymer index (BPI) calculated according to the following formula 1 is about 18 or more, preferably about 19 or more, and more preferably about 20 or more, for example about 19 to about 25, preferably about 20 To about < RTI ID = 0.0 > 25. &Lt; / RTI >

[Formula 1]

In the above formula 1, CRC denotes the centrifuge supporting capacity (unit: g / g) measured by EDANA Test Method 441.2-02 and ln (content of water component) is the water content measured by EDANA Test Method 270.2 Means the natural log value of the component content (unit: wt%).

In addition, the normal water content of the hydrogel polymer obtained by such a method may be about 40 to about 80 wt%. On the other hand, throughout the present specification, the term "moisture content" means the moisture content of the total functional gelated polymer weight minus the weight of the hydrogel polymer in dry 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.

Next, the step of drying the obtained hydrogel polymer is carried out.

At this time, if necessary, the step of coarse grinding may be further carried out before drying in order to increase the efficiency of the drying step.

Wherein the milling step may be milled so that the size of the hydrogel polymer is from about 2 to about 10 mm.

It is technically not easy to crush to less than 2 mm in diameter due to the high moisture content of the hydrogel polymer, and there may be a phenomenon that the crushed particles cohere to each other. On the other hand, when the particle size is larger than 10 mm, the effect of increasing the efficiency of the subsequent drying step is insignificant.

Drying is carried out on the hydrogel polymer immediately after polymerization as described above, or without the pulverization step. The drying temperature of the drying step may be about 150 to about 250 ° C. If the drying temperature is lower than 150 ° C, the drying time becomes excessively long and the physical properties of the superabsorbent resin to be finally formed may deteriorate. When the drying temperature exceeds 250 ° C, only the polymer surface is excessively dried, And the physical properties of the finally formed superabsorbent resin may be deteriorated. Thus, preferably, the drying can proceed at a temperature of from about 150 to about 200 < 0 > C, more preferably from about 160 to about 180 < 0 > C.

On the other hand, in the case of drying time, it may proceed for about 20 to about 90 minutes, but is not limited thereto, considering process efficiency and the like.

Next, a step of pulverizing the dried polymer obtained through such a drying step is carried out.

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. Preferably, the polymer having a particle diameter of about 150 to about 850 탆 is classified, and the polymer powder having such a particle diameter can be produced through the surface cross-linking reaction step.

Next, the surface cross-linking reaction can be carried out by adding a surface cross-linking agent to the pulverized polymer.

The surface cross-linking is a step of increasing the cross-linking density near the surface of the superabsorbent polymer particle in relation to the cross-linking density inside the particle. Generally, the surface cross-linking agent is applied to the surface of the superabsorbent resin particles. Thus, this reaction takes place on the surface of the superabsorbent resin particles, which improves the crosslinkability on the surface of the particles without substantially affecting the interior of the particles. Thus, the surface cross-linked superabsorbent resin particles have a higher degree of crosslinking in the vicinity of the surface than in the interior.

At this time, the surface cross-linking agent is not limited as long as it is a compound capable of reacting with a functional group contained in the polymer.

Preferably, in order to improve the properties of the resulting superabsorbent resin, a polyhydric alcohol compound as the surface crosslinking agent; Epoxy compounds; Polyamine compounds; Halo epoxy compounds; A condensation product of a haloepoxy compound; Oxazoline compounds; Mono-, di- or polyoxazolidinone compounds; Cyclic urea compounds; Polyvalent metal salts; And an alkylene carbonate compound can be used.

The constitution of the method of adding the surface cross-linking agent to the polymer is not limited. A method in which a surface cross-linking agent and a polymer powder are mixed in a reaction tank or spraying a surface cross-linking agent onto a polymer powder, a method in which a polymer and a surface cross-linking agent are continuously supplied and mixed in a continuously operated mixer can be used.

When the surface cross-linking agent is added, water may be further mixed and added. When water is added, there is an advantage that the surface cross-linking agent can be uniformly dispersed in the polymer. The amount of added water is about 1 to about 10 parts by weight per 100 parts by weight of the polymer for the purpose of inducing even dispersion of the surface cross-linking agent and preventing aggregation of the polymer powder and optimizing the surface penetration depth of the cross- . &Lt; / RTI >

Surface crosslinking agent is added to the surface of the polymer particles by heating at a temperature of about 140 to about 220 DEG C, preferably about 160 to about 200 DEG C, for about 15 to about 90 minutes, preferably about 20 to about 80 minutes, Reaction and drying can be performed at the same time. If the crosslinking reaction temperature is less than 140 ° C, the surface cross-linking reaction may not occur. If the crosslinking reaction temperature is more than 220 ° C, foreign substances and odors due to carbonization may occur, May occur. When the crosslinking reaction time is less than 15 minutes, a sufficient crosslinking reaction can not be performed. When the crosslinking reaction time exceeds 90 minutes, excessive surface crosslinking reaction may cause degradation of physical properties due to damage of the polymer particles have.

The temperature raising means for the surface cross-linking reaction is not particularly limited. A heating medium can be supplied, or a heating source can be directly supplied and heated. At this time, as the type of usable heat medium, it is possible to use a heated fluid such as steam, hot air or hot oil. However, the present invention is not limited thereto, and the temperature of the heat medium to be supplied can be controlled by means of heat medium, It can be appropriately selected in consideration of the target temperature. On the other hand, as a heat source to be directly supplied, a heating method using electricity or a heating method using gas may be mentioned, but the present invention is not limited to the above-mentioned examples.

As described above, the final superabsorbent resin obtained by cross-linking the superabsorbent resin obtained by the production method of the present invention as a base polymer has excellent characteristics in terms of centrifugal support capacity (CRC) and pressure absorption capacity (AUP) Lt; / RTI > For example, the superabsorbent resin surface-crosslinked with the superabsorbent resin obtained by the production method of the present invention has a CRC of at least about 33 g / g, preferably at least about 36 g / g, and an AUP of at least about 25 g / g . The pressure absorption capacity (AUP) means the value measured by EDANA Test Method 442.2-02 under a load of 0.7 psi.

The present invention will be described in more detail in the following Examples. However, the following examples are illustrative of the present invention, and the present invention is not limited by the following examples.

< Example >

Example One

1-1 Production of base resin

100 g of acrylic acid monomer, 38.9 g of caustic soda (NaOH) and 103.9 g of water were mixed, and 0.1 g of sodium persulfate as a thermal polymerization initiator and 0.1 g of diphenyl (2,4,6-trimethylbenzoyl) -phosphine Oxide and 0.3 g of polyethylene glycol diacrylate as a crosslinking agent were added to prepare a monomer composition.

The monomer composition was kept at an internal temperature of 80 占 폚, and the UV light was left for 1 minute in a reactor equipped with an ultraviolet irradiator of a mercury UV lamp light source, and the polymerization reaction was further continued for 2 minutes in a light source. The total light irradiation time of 1 minute is divided into three sections of Q1: 0 to 15 seconds, Q2: 15 to 50 seconds, and Q3: 50 to 60 seconds, and the amount of light in Q1 is 10 mW, the amount of light in Q2 is 5 mW , And the amount of light in Q3 was changed to 14 mW.

After the polymerization, the hydrogel polymer was pulverized into particles having a particle size of 10 mm or less by using a pulverizer, dried at 180 ° C for 30 minutes through a hot air dryer, re-pulverized using a rotary mixer, A superabsorbent resin (BR1) used as a resin was prepared.

1-2. Preparation of superabsorbent resin

Of the prepared superabsorbent resin (BR1), 95 g of a fine powder having a particle size of 180 탆 or less and 5 g of a polymer having a particle diameter of 300 탆 or more were mixed and 100 g of water was added to reassemble. The reassembly was dried at 180 캜 for 30 minutes to prepare a highly water absorbent resin having a water content of 3% or less. After grinding and classification, 0.1 wt% of ethyleneglycol diglycidyl epoxide was added, and the mixture was homogeneously mixed. Then, the surface cross-linking reaction was carried out at 140 ° C for 1 hour. This was classified into 20 to 100 meshes to prepare a superabsorbent resin (PD1).

Example 2

A superabsorbent resin (BR2) was prepared in the same manner as in Example 1-1 except that the polymerization was carried out by changing the light amount in Q1 to 12 mW, the light amount in Q2 to 8 mW, and the light amount in Q3 to 12 mW.

The superabsorbent resin (PD2) was prepared by subjecting the superabsorbent resin (BR2) having been polymerized to the re-assembly and surface cross-linking reaction in the same manner as in Example 1-2.

Example 3

A superabsorbent resin (BR3) was prepared in the same manner as in Example 1-1 except that the polymerization was carried out by changing the light amount in Q1 to 10 mW, the light amount in Q2 to 4 mW, and the light amount in Q3 to 14 mW.

The superabsorbent resin (PD3) was prepared by subjecting the superabsorbent resin (BR3) having been polymerized to the re-assembly and surface cross-linking reaction in the same manner as in Example 1-2.

Example 4

A superabsorbent resin (BR4) was prepared in the same manner as in Example 1-1 except that the polymerization was carried out by changing the amount of light in Q1 to 10 mW, the amount of light in Q2 to 3 mW, and the amount of light in Q3 to 14 mW.

The superabsorbent resin (PD4) was prepared by subjecting the superabsorbent resin (BR4) having been polymerized to the re-assembly and surface cross-linking reaction in the same manner as in Example 1-2.

Example 5

A superabsorbent resin (BR5) was prepared in the same manner as in Example 1-1 except that the polymerization was carried out by changing the light quantity at Q1 to 10 mW, the light quantity at Q2 to 9 mW, and the light quantity at Q3 to 14 mW.

The superabsorbent resin (PD5) was prepared by subjecting the superabsorbent resin (BR5) having been polymerized to the re-assembly and surface cross-linking reaction in the same manner as in Example 1-2.

Comparative Example One

A superabsorbent resin (BR6) was prepared in the same manner as in Example 1-1 except that the amounts of light in Q1, Q2 and Q3 were all fixed at 10 mW and polymerization was carried out.

The superabsorbent resin (PD6) was prepared by subjecting the superabsorbent resin (BR6) having been polymerized to the re-assembly and surface cross-linking reaction in the same manner as in Example 1-2.

Comparative Example 2

A superabsorbent resin (BR7) was prepared in the same manner as in Example 1-1 except that the amounts of light in Q1, Q2 and Q3 were all fixed at 12 mW and polymerization was carried out.

The superabsorbent resin (PD7) was prepared by subjecting the superabsorbent resin (BR7) having been polymerized to the re-assembly and surface cross-linking reaction in the same manner as in Example 1-2.

Comparative Example 3

A superabsorbent resin (BR8) was prepared in the same manner as in Example 1-1 except that the amounts of light in Q1, Q2 and Q3 were all fixed at 8 mW and polymerization was carried out.

The superabsorbent resin (PD8) was prepared by subjecting the superabsorbent resin (BR8) having been polymerized to the re-assembly and surface cross-linking reaction in the same manner as in Example 1-2.

Comparative Example 4

A superabsorbent resin (BR9) was prepared in the same manner as in Example 1-1 except that the polymerization was carried out by changing the amount of light in Q1 to 10 mW, the amount of light in Q2 to 6 mW, and the amount of light in Q3 to 6 mW.

The superabsorbent resin (PD9) was prepared by subjecting the superabsorbent resin (BR9) having been polymerized to the re-assembly and surface cross-linking reaction in the same manner as in Example 1-2.

(CRC, unit: g / g) according to EDANA Test Method 441.2-02 and EDANA Test Method 270.2 for the superabsorbent resins of Examples 1 to 5 and Comparative Examples 1 to 4, (AUP, unit: g / g) under the load of 0.7 psi according to the EDANA Test Method 442.2-02 and the BPI was calculated according to the following Formula 1 to obtain Tables 1 and 2 Respectively.

[Formula 1]

CRC
(g / g) Water component
(weight%) BPI
(Base Polymer Index) Example 1 (BR1) 43.3 13.5 20.0 Example 2 (BR2) 43.8 13.8 20.0 Example 3 (BR3) 42.0 12.7 20.0 Example 4 (BR4) 38.6 12.7 18.6 Example 5 (BR5) 39.0 13.3 18.4 Comparative Example 1 (BR6) 42.7 16.7 18.3 Comparative Example 2 (BR7) 41.8 17.6 17.6 Comparative Example 3 (BR8) 40.2 15.8 17.7 Comparative Example 4 (BR9) 39.2 13.4 18.5

CRC
(g / g) 0.7psi AUP
(.g / g) Example 1 (PD1) 36.5 25.4 Example 2 (PD2) 36.2 25.1 Example 3 (PD3) 36.6 25.0 Example 4 (PD4) 33.8 25.1 Example 5 (PD5) 33.6 25.5 Comparative Example 1 (PD6) 33.2 23.8 Comparative Example 2 (PD7) 33.8 23.9 Comparative Example 3 (PD8) 33.7 23.5 Comparative Example 4 (PD9) 33.1 25.2

Referring to Tables 1 and 2, the superabsorbent resin prepared using the polymerization reactor of the present invention exhibited a high CRC and a low water content, indicating a high BPI. In addition, the resin obtained by performing the surface cross-linking reaction using the superabsorbent resin prepared using the polymerization reactor of the present invention as the base resin also exhibited high CRC and AUP.

10, 20, 30: raw material supply part
40: solvent supply unit
50: Monomer composition supply part
60:
60a, 60b, and 60c:
65: aging area
70: Conveyor belt
80: Reaction part
90:

Claims

A monomer composition supplier for supplying a monomer composition comprising a water-soluble ethylenically unsaturated monomer, a polymerization initiator and a solvent; And
A reaction part connected to the monomer composition supply part and including a light irradiation part for supplying light to the monomer composition,
Wherein the light irradiation unit includes first through third light irradiation areas in order along the longitudinal direction of the reaction part, and when the light amounts of the first through third light irradiation areas are respectively Q1 through Q3, Q3 Q1 > Q2 Satisfying the relationship,
Polymerization reactor for producing superabsorbent resin.

The method according to claim 1,
Wherein Q2 is 40 to 80% and Q3 is 100 to 140% when Q1 is 100%.

The method according to claim 1,
Wherein the first to third light irradiation regions divide the total area of the light irradiation portions by 20 to 30%: 40 to 70%: 10 to 30%, respectively, when the total area of the light irradiation portions is 100% Polymerization reactor for producing superabsorbent resin.

Preparing a monomer composition comprising a water-soluble ethylenically unsaturated monomer, a polymerization initiator, and a solvent; And
And polymerizing the monomer composition with the polymerization reactor of claim 1.

5. The method of claim 4,
Wherein the superabsorbent resin has a BPI (Base Polymer Index) of 18 or more calculated according to the following formula 1:
[Formula 1]

In the above formula 1, CRC denotes the centrifuge supporting capacity (unit: g / g) measured by EDANA Test Method 441.2-02 and ln (content of water component) is the water content measured by EDANA Test Method 270.2 Means the natural logarithm of the content of the component (unit: wt%).