KR101393681B1 - Preparation method of super absorbent polymer - Google Patents

Abstract

The present invention relates to a method for producing a superabsorbent resin, and more particularly, to a method for producing a superabsorbent resin which forms a hydrogel polymer having a water content of 30 wt% Of the present invention.
The present invention enables to keep the thickness of the charged monomer composition constant and to dry the hydrogel polymer produced at the same time as the polymerization, thereby greatly reducing the water content of the hydrogel polymer before cutting and crushing, It is possible to easily cut and crush it, to improve the drying efficiency, to exhibit energy saving effect, and to obtain a high-quality superabsorbent resin.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for producing a superabsorbent resin,

The present invention relates to a method for producing a superabsorbent resin, and more particularly, to a method for producing a superabsorbent resin having a desired particle size and a method of manufacturing the same, Absorbent resin to improve the efficiency of the entire manufacturing process of the superabsorbent resin.

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.

As a method of producing such a superabsorbent resin, there are known methods such as reversed-phase suspension polymerization or aqueous solution polymerization. The reversed-phase suspension polymerization is disclosed in, for example, Japanese Unexamined Patent Publication No. 56-161408, Unexamined Japanese Patent Application No. 57-158209, and Japanese Unexamined Patent Publication No. 57-198714. Examples of the method by aqueous solution polymerization include a thermal polymerization method in which the polymerization gel is polymerized while being cooled in a kneader equipped with a shaft, and a photopolymerization method in which a high concentration aqueous solution is irradiated with ultraviolet rays or the like on a belt to perform polymerization and drying simultaneously .

Japanese Patent Application Laid-Open No. 2004-250689 discloses a method for producing an absorbent molded article in which polymerization is carried out by intermittently irradiating an aqueous solution containing a photopolymerization initiator and a water-soluble ethylenic unsaturated monomer. Korean Patent No. 0330127 discloses a method for producing an absorbent resin in which a water-soluble ethylenically unsaturated monomer having a crosslinking agent is polymerized by irradiating ultraviolet rays in the presence of a peroxide and a radical photopolymerization initiator having a benzoyl group.

The hydrogel polymer obtained through polymerization reaction as described above generally produces powdery superabsorbent resin through cutting, drying, pulverizing, and surface treatment processes.

However, due to the nature of the hydrogel polymer, the water content is from 35 to 65% by weight, and because of the high adhesive property of the gel, 50 to 60% by weight of shrinkage quantity is maintained for the reduction of adhesion and subsequent processing.

However, as described above, since the gel particles having a high water content still contain excess water, the water gel polymer having a large amount of water in the cutting and milling step tangles or sticks to the inner wall of the cutting device or the pulverizing device, The polymer can not be cut or milled in one size. Therefore, since the pulverized particles are aggregated, they exhibit an uneven particle shape and have a large particle size, resulting in very poor drying efficiency. In addition, when the temperature is increased in the drying process to lower the moisture content, the temperature of the hydrogel polymer and the superabsorbent resin may become higher, which may adversely affect the physical properties. Further, even if the temperature is not raised, So that efficient drying can not proceed.

Further, in the case of the conventional method, in order to obtain a superabsorbent resin having small particles, the polymer having a large particle size needs to be subjected to additional pulverization and drying steps after the drying process, so that the whole process becomes cumbersome and complicated. It is possible to reduce the physical properties of the resin.

In order to solve the above problems, there is known a method of adding water or a surfactant to the hydrogel polymer (JP 59-30826, JP 59-119172), etc. However, when a surfactant or the like is added, The additives remain in the resulting polymer, which may adversely affect the performance of the super absorbent polymer product. In addition, when water or the like is added, the amount of water to be removed in the final drying step is increased, and the drying time and the energy consumption required for drying are wasted, so that the efficiency of the process for producing a superabsorbent resin can be secured I will not.

Accordingly, the present inventors have completed the present invention while repeatedly studying a method for efficiently producing a superabsorbent resin without impairing physical properties of the final superabsorbent resin.

Accordingly, the present invention can produce a polymer having an optimized water content by lowering the water content of a water-soluble polymer in the production of a superabsorbent resin, and by reducing the adhesion of the gel, it is possible to facilitate cutting and pulverization processes, And a method for producing a superabsorbent resin capable of producing a high absorbency resin.

Another object of the present invention is to provide a process for producing a superabsorbent resin which enables production of small particles after pulverization and can expect energy saving effect in a drying process under a minimum drying condition.

Another object of the present invention is to provide a method for producing a superabsorbent resin which does not inhibit the physical properties of the finally obtained superabsorbent resin.

The present invention relates to a process for preparing a monomer composition comprising: forming a monomer composition comprising a water-soluble ethylenically unsaturated monomer and a polymerization initiator; Introducing the monomer composition into a polymerization reactor and conducting drying in a polymerization reactor while progressing polymerization to form a hydrogel polymer having a water content of 30 wt% or less; And cutting and pulverizing the hydrogel polymer. The present invention also provides a method for producing a superabsorbent resin.

The monomer composition can be introduced at a constant rate such that the hydrogel polymer formed in the polymerization reactor maintains a thickness of 0.1 cm to 2.0 cm.

Hereinafter, a method of producing a superabsorbent resin according to a specific embodiment of the present invention will be described.

When polymerization is normally carried out on a belt, a sheet-like polymer having a width corresponding to the width of the belt is obtained. At this time, the thickness of the polymer sheet varies depending on the concentration and the feeding rate of the monomer composition to be charged, but usually a polymer in the form of a sheet having a thickness of 0.5 to 5 cm is obtained. In addition, thermal polymerization or UV polymerization can be carried out on a kneader having a plurality of stirring axes. At this time, the size of the obtained hydrogel polymer varies depending on the concentration of the monomer composition to be injected and the injection rate. A hydrogel polymer having a weight average particle diameter of usually 2 to 50 mm is obtained.

However, the hydrogel polymer according to the above method controls the water content according to the addition of the surfactant, and thus shows a shrunk yield of 50 to 60% by weight before the surface treatment. Therefore, in such a case, the gel adhesion is so high that the efficiency in subsequent crushing and drying steps is greatly lowered, and the physical properties of the finally obtained superabsorbent resin can also be inhibited.

On the other hand, the inventors of the present invention can produce a hydrogel polymer having a water content of 30 wt% or less before the surface treatment by progressing a certain degree of drying simultaneously with the polymerization of the hydrogel polymer through thickness control in the polymerization process of the monomer composition . In addition, it was confirmed that it is possible to optimize the drying process by cutting and grinding by lowering the gel adhesion force by controlling the optimized water content, and at the same time, it is possible to produce a superabsorbent resin having uniform and fine particles and excellent physical properties.

Then, according to one embodiment of the present invention, there is provided a process for producing a polymer composition, comprising: forming a monomer composition comprising a water-soluble ethylenically unsaturated monomer and a polymerization initiator; Introducing the monomer composition into a polymerization reactor and conducting drying in a polymerization reactor while progressing polymerization to form a hydrogel polymer having a water content of 30 wt% or less; And cutting and crushing the hydrogel polymer.

At this time, the present invention can optimize the water content of the hydrogel polymer to 30% by weight or less by simultaneously drying while maintaining the thickness of the hydrogel polymer formed by the polymerization reaction in the polymerization reactor.

Preferably, the present invention optimizes the water content of the hydrous gel polymer to 20 to 30 wt.%, Thereby providing excellent physical properties and lowering the gel adhesion during the cutting and milling process. Accordingly, the present invention can improve the processability by significantly lowering the sticking property to the cutter or the crushing machine when crushing the hydrogel polymer, as in the prior art. Thus, in the subsequent pulverization step, the hydrogel polymer can be effectively pulverized into a homogeneous size without adhering to the pulverizing blade, the pulverizing shaft, the inner wall of the apparatus or the like of the cutter or the pulverizer.

On the other hand, when the water content of the hydrogel polymer is less than 20% by weight, the physical properties may be lowered even if the gel adhesion force is not high. If the water gel strength is more than 30% by weight, the gel adhesion may be increased. That is, when the water content of the hydrous gel polymer is 30 to 50% by weight, although the physical properties corresponding to the present invention may be exhibited, the hydrogel polymer adheres to the inner wall of the cutter, the inner wall of the pulverizer, And it is possible to cause a malfunction of the rotating blade or the cutting blade due to the sticking of the hydrogel polymer. Also, when the water content of the hydrogel polymer is 50 to 60% by weight as in the conventional method, since the gel particles after the polymerization are high in the high water content as described above and the excessive adhesion of water to the gel is high, The drying efficiency is also very bad.

Further, the present invention can obtain fine particles having a uniform particle size distribution of a desired size with ease of the cutting and grinding process, and the drying process is easy, so that a superabsorbent resin can be obtained economically. In particular, the present invention does not require the use of a surfactant that is added additionally for the purpose of improving the adhesion as in the prior art, and the physical properties of the final formed superabsorbent resin are lowered, or the skin There is no fear of stimulation.

For this purpose, the present invention can be applied at a constant rate so that the hydrogel polymer formed in the polymerization reactor of the monomer composition maintains a thickness of 0.1 cm to 2.0 cm. The input speed can be adjusted according to the belt width and operation speed. With this, along with the polymerization of the monomer composition and the formation of the hydrogel polymer, a certain degree of drying can be made more effective, so that the above-mentioned low-moisture-content hydrogel polymer can be formed more effectively.

 At this time, when the thickness of the monomer composition is less than 0.1 cm, the thickness of the hydrogel polymer formed becomes thin, and there is a limitation in the amount of the polymer gel. Further, when the monomer composition is added at a thickness of 2.0 cm or more, the thickness of the hydrogel polymer formed is too thick to reduce the water content, and it is necessary to resume drying for a long time in order to obtain a desired water content.

At this time, the monomer composition feeding unit for feeding the monomer composition into the polymerization reactor may be provided with a means for controlling the speed, and a temperature adjusting means may be provided if necessary.

On the other hand, the polymerization of the monomer composition is not particularly limited, and a method used for producing a common superabsorbent resin can be used. For example, the polymerization may include polymerization of the monomer composition includes thermal polymerization or UV polymerization. However, the polymerization temperature may be from 25 to 150 ° C, and the reaction time may be from 10 seconds to 30 minutes. In particular, it can proceed by irradiating light for 10 seconds to 5 minutes of UV polymerization. The amount of ultraviolet light may be 0.1 to 300 mW / cm < ² > during UV irradiation. The light source and the wavelength range used in the UV irradiation can also be those well known in the art.

The drying method in the drying step of the hydrogel polymer which proceeds simultaneously with the polymerization may be selected and carried out without limitation of the constitution so long as the moisture can be removed from the hydrogel polymer to lower the water content to 30% by weight or less. Preferably, the drying method of the hydrogel polymer may include neutralizing heat on the polymer itself in the polymerization reactor or natural drying on the heat of dissolution. Further, the drying method of the hydrogel polymer may be performed by infrared irradiation, hot air drying, microwave irradiation or ultraviolet irradiation by a drying device connected to the polymerization reactor.

The drying temperature and time may be appropriately selected according to the water content of the polymer polymerized through thermal polymerization or UV polymerization, and it is preferably carried out at a temperature of 120 to 200 ° C for 20 to 120 minutes. When the drying temperature is less than 120 ° C., the drying effect is insignificant, so that the drying time is excessively long and it is difficult to lower the water content by 30% by weight or less. In addition, when the drying temperature exceeds 200 캜, only the surface of the hydrogel polymer is locally overly dried, so that a large amount of fine powder can be generated in the subsequent pulverization step.

On the other hand, the kind of the polymerization reactor is not particularly limited as long as it is used for producing a conventional superabsorbent resin, and may include a continuous or discontinuous moving conveyor belt or a kneader. Preferably, the polymerization reactor used in the present invention can use a continuously moving conveyor belt. Further, when the polymerization reactor is continuously moved in one direction, it can be moved in one direction at a speed of 0.5 to 10 meters / minute. Also, when polymerization is carried out on a kneader having a plurality of agitating shafts, the water content of the hydrogel polymer can be lowered by controlling the rate of the charged monomer composition to form an appropriate amount of hydrogel polymer. In this case, when the polymerization is proceeded in the kneader, drying through a drying device connected to the inside or outside of the polymerization reactor rather than natural drying may be effective in lowering the water content.

At this time, the polymerization of the water-soluble ethylenic unsaturated monomer is preferably carried out in an aqueous solution state.

The water-soluble ethylenically unsaturated monomer used in the present invention can be used without limitation in the constitution as long as it is a monomer usually used in the production of a superabsorbent resin. At least one selected from the group consisting of anionic monomers and salts thereof, nonionic hydrophilic-containing monomers, and amino group-containing unsaturated monomers and quaternary amines thereof can be used.

Specifically, the water-soluble ethylenic unsaturated monomer is at least one monomer selected from the group consisting of acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, 2- acryloylethanesulfonic acid, 2- methacryloylethanesulfonic acid, 2- Anionic monomers of 2- (meth) acrylamide-2-methylpropanesulfonic acid and its salts; (Meth) acrylamide, N-substituted (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, methoxypolyethylene 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 and (N, N) -dimethylaminopropyl (meth) . More preferably, the water-soluble ethylenically unsaturated monomer can use acrylic acid and a salt thereof, which is advantageous in that it has excellent physical properties.

The concentration of the water-soluble ethylenically unsaturated monomer in the monomer composition may be appropriately selected in consideration of the polymerization time and the reaction conditions, and preferably 20 to 60% by weight. When the concentration of the water-soluble ethylenically unsaturated monomer is less than 20% by weight, the yield is low and the economical efficiency is low. When the concentration is more than 60% by weight, the property is deteriorated and the monomer solubility is deteriorated.

The polymerization initiator may be used in a different polymerization initiator depending on whether the polymerization method is thermal polymerization or photopolymerization by UV irradiation. As the thermal polymerization initiator in the polymerization initiator, at least one selected from the group consisting of an azo-based initiator, a peroxide-based initiator, a redox-based initiator, and an organic halide initiator may be used. Examples of the photopolymerization initiator include acetophenone, benzoin, benzophenone, benzyl and its derivatives such as diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1- Acetopetone derivatives such as hydroxyethoxy) phenyl- (2-hydroxy) -2-propyl ketone, 1-hydroxycyclohexyl phenyl ketone and the like; Benzoin alkyl ethers such as benzoin methyl ether, benzoyl ethyl ether, benzoin isopropyl ether and benzoin isobutyl ether; benzophenone derivatives such as methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide and (4-benzoylbenzyl) trimethylammonium chloride; Thioxanthone-based compounds; Acylphosphine oxide derivatives such as bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide and diphenyl (2,4,6-trimethylbenzoyl) -phosphine oxide; (2-methyl-N- [1,1'-bis (hydroxymethyl) -2-hydroxyethyl) propionamide] such as 2-hydroxymethylpropionitrile and 2,2 ' And the like may be used.

The polymerization initiator may be used in an amount of 0.01 to 1.0% by weight based on the total monomer composition.

The monomer composition according to the present invention may further comprise a crosslinking agent.

The crosslinking agent may be selected from the group consisting of a water-soluble substituent of an ethylenically unsaturated monomer, a crosslinking agent having at least one ethylenic unsaturated group and at least one functional group capable of reacting with the water-soluble substituent of the ethylenically unsaturated monomer, or a mixture thereof; And a water-soluble substituent of the ethylenically unsaturated monomer, a cross-linking agent having at least two functional groups capable of reacting with a water-soluble substituent formed by hydrolysis of the vinyl monomer, and a mixture thereof. . Examples of the crosslinking agent having two or more ethylenic unsaturated groups include bisacrylamide having 8 to 12 carbon atoms, bismethacrylamide, poly (meth) acrylate of polyol having 2 to 10 carbon atoms, and poly (meth) acrylate having 2 to 10 carbon atoms (Meth) acrylate, ethyleneoxy (meth) acrylate, propyleneoxy (meth) acrylate, glycerin diacrylate, glycerin At least one selected from the group consisting of triacrylate, trimethylolpropane triacrylate, triallylamine, triaryl cyanurate, triallyl isocyanate, polyethylene glycol, diethylene glycol and propylene glycol can be used.

The crosslinking agent may be used in an amount of 0.01 to 0.5% by weight based on the total monomer composition.

Meanwhile, in one embodiment of the present invention, the functional gel polymer having a water content of 30% by weight or less obtained by carrying out drying at the same time as the polymerization of the monomer composition may further include a step of cutting to a predetermined size before the pulverization step . For example, the hydrogel polymer can be cut to a size of 0.1 cm to 5 cm using a conventional cutting device and then subjected to a pulverization process.

According to these embodiments, the dried polymer is subjected to a cleavage and grinding step, which may include cutting the hydrogel polymer to a constant size (0.1 cm to 5 cm in size). The structure of the apparatus used in the cutting step may be any of those used for ordinary superabsorbent resins. For example, the cutting process may be performed through a cutter having at least one of a vertical cutting blade, a scraper, a horizontal cutting rotary blade, and a casing.

In addition, the pulverization can be selected without limiting the constitution as long as it is a method used for pulverizing a superabsorbent resin or the like. Preferably, any one of the grinding apparatuses selected from the group consisting of a pin mill, a hammer mill, a screw mill, and a roll mill may be selected and pulverized. In this case, the average particle diameter of the superabsorbent resin particles after the pulverization step is preferably in the form of a powder having a particle size of from 150 μm to 850 μm.

In the present invention, the post-milled particles may further include a step of surface-treating, drying or surface-treating after drying.

The constitution of the apparatus in the additional drying step is not particularly limited, and drying can be performed by, for example, infrared irradiation, hot air, microwave irradiation, or ultraviolet irradiation. The drying temperature and time may be appropriately selected according to the water content of the polymer polymerized by thermal polymerization or UV polymerization, and preferably, it is preferably carried out at a temperature of 80 to 200 ° C for 20 to 120 minutes. When the drying temperature is lower than 80 ° C., the drying effect is insignificant and the drying time is excessively long. When the drying is performed at a temperature exceeding 200 ° C., there is a problem that the superabsorbent resin is thermally decomposed.

In such embodiments, the moisture content after drying of the hydrous gel polymer polymerized through thermal polymerization or UV polymerization may be from 2 to 15% by weight. Here, the water content of the hydrogel polymer means the amount of moisture occupied by the weight of the whole polymer gel minus the weight of the hydrogel polymer and the weight of the polymer in the dry state.

1 to 3 schematically show a method of manufacturing a superabsorbent resin according to various embodiments of the present invention.

As shown in Figs. 1 to 3, the present invention mixes a water-soluble ethylenically unsaturated monomer and a polymerization initiator in a mixer 10 to form a monomer composition. At this time, as a mixer, a supply part and a solvent supply part of the raw material such as the monomer and the polymerization initiator may be connected.

The present invention then conveys the monomer composition to the monomer composition feed 20 via a transfer line connected to the mixer 10.

Then, the monomer composition is fed to the polymerization reactor 30 at a constant speed, including a belt 36 which is rotatable about the rotating shafts 32, 34 and made to advance in a predetermined direction. Then, polymerization and simultaneous drying are carried out on the belt to obtain a hydrogel polymer on the sheet, and the thickness (a) is maintained at 0.1 cm to 2.0 cm, thereby forming a hydrogel polymer 40 having a water content of 30% by weight or less . The hydrogel polymer is transferred from the polymerization reactor 30 to the cutter 60 and then cut through the cutting means 52 to obtain a hydrogel polymer 42 having a water content of 30 wt% or less. The cut functionalized gel polymer can then be transferred to a pulverizer, pulverized into fine particles, dried and subjected to a surface treatment process, and made into a highly absorbent resin having uniform and fine particles. At this time, the drying process may be further performed before the pulverizing process. The cutter may also be replaced by a mill.

At this time, in the case of the first embodiment of the present invention, drying of the hydrogel polymer formed by polymerization as in Fig. 1 can be performed by natural drying.

2, the drying apparatus 60 is installed on the upper part of the polymerization reactor 30 so that heat is uniformly transferred to the hydrogel polymer formed on the surface of the polymerization reactor by applying a predetermined temperature, Simultaneously with the polymerization, drying on the hydrogel polymer (40) can be carried out.

In the case of the third embodiment, the drying apparatus 62 may be installed in the direction in which the hydrogel polymer is formed in the polymerization reactor 30, as shown in FIG. 3, so that the hydrogel polymer 40 can be dried simultaneously with polymerization have.

As described above, in the above-mentioned embodiments, the water content of the hydrogel polymer is very low, i.e., 30% or less as compared with the conventional 50 to 60%, so that it can be effectively pulverized without sticking to the inner wall of the pulverizer at the time of pulverization. In addition, a hydrogel polymer having a uniform particle size distribution can be obtained according to an optimum amount of water, and its drying efficiency can be greatly improved.

Accordingly, the superabsorbent resin of the present invention not only can effectively remove moisture after polymerization, but also does not deteriorate the physical properties of the ultrafine water-absorbent resin to be finally prepared, thereby improving the efficiency of the entire process .

The present invention relates to a process for preparing a monomer composition comprising: forming a monomer composition comprising a water-soluble ethylenically unsaturated monomer and a polymerization initiator; Introducing the monomer composition into a polymerization reactor and conducting drying in a polymerization reactor while progressing polymerization to form a hydrogel polymer having a water content of 30 wt% or less; And cutting and pulverizing the hydrogel polymer. The present invention also provides a method for producing a superabsorbent resin.

The monomer composition can be introduced at a constant rate such that the hydrogel polymer formed in the polymerization reactor maintains a thickness of 0.1 cm to 2.0 cm.

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1 is a schematic view briefly showing a process of a method of manufacturing a superabsorbent resin according to a first embodiment of the present invention.
Fig. 2 is a schematic view briefly showing a process of a method for producing a superabsorbent resin according to a second embodiment of the present invention.
3 is a schematic view briefly showing a process of a method of manufacturing a superabsorbent resin according to a third embodiment of the present invention.

Best Mode for Carrying Out the Invention Hereinafter, the function and effect of the present invention will be described in more detail through specific examples of the present invention. It is to be understood, however, that these embodiments are merely illustrative of the invention and are not intended to limit the scope of the invention.

Example  One

A superabsorbent resin was prepared according to the method shown in Fig.

0.1 g of polyethylene glycol diacrylate as a crosslinking agent, 0.033 g of diphenyl (2,4,6-trimethylbenzoyl) -phosphine oxide as an initiator, 38.9 g of caustic soda (NaOH) and 103.9 g of water were mixed, A monomer aqueous solution composition having a monomer concentration of 50% by weight was prepared.

Then, the monomer aqueous solution composition was put on a conveyer belt continuously moving through a monomer supplying portion, irradiated with ultraviolet rays (irradiation amount: 2 mW / cm 2), and subjected to UV polymerization for 2 minutes.

The hydrogel polymer formed at this time was naturally dried at the same time as it moved through the rotating shaft on the belt. Therefore, after that, it was transferred into a pulverizer in a state of natural drying, and pulverized into a size of 1 × 1 mm. The water content was measured to be 30% by weight of a hydrogel polymer.

Then, the hydrogel polymer was dried in a hot-air dryer at 150 ° C. for 5 hours, pulverized with a pin mill and then sieved to obtain a superabsorbent resin having a particle diameter of 150 to 850 μm.

Thereafter, the surface-crosslinking of the superabsorbent resin was carried out using a 3% solution of ethylene glycol diglycidyl ether, followed by a reaction at 120 ° C for 1 hour. After the pulverization, a surface treatment with a particle size of 150 to 850 μm To obtain a superabsorbent resin.

Example  2

2, an ultraviolet drying apparatus was installed on the upper part of the polymerization reactor on the belt to polymerize the same, and the temperature of the polymerization reactor was maintained at 100 DEG C, and the simultaneous drying was carried out on the hydrogel polymer. The procedure of Example 1 was repeated to prepare a superabsorbent resin. At this time, when the drying apparatus was used, the water content of the hydrogel polymer was 27% by weight.

Example  3

3, an ultraviolet drying apparatus was installed inside the polymerization reactor on the belt, and the polymerization reactor was maintained at a temperature of 100 DEG C, and the dried hydrous gel polymer was irradiated with infrared light for 2 minutes to be dried , A superabsorbent resin was prepared in the same manner as in Example 1. In this case, when the drying apparatus was used, the water content of the hydrogel polymer was 25% by weight.

Comparative Example  One

10 g of water and 0.05 g of a surfactant (sodium lauryl sulfate, SLS) were poured into 100 g of the hydrogel polymer of Example 1, followed by pulverization. As a result, a hydrous gel polymer having a water content of 50% by weight was prepared, and when it was added to the pulverizing process, entanglement phenomenon occurred and hydrogel polymer adhered to the inner wall of the pulverizer. As a result, particles having a size as large as 5 mm x 5 mm were obtained in a rolled state, and secondary drying was carried out at a temperature of 150 ° C for 5 hours. Thereafter, the hydrogel polymer having been subjected to the second drying was secondarily pulverized and surface-treated in the same manner as in Example 1 to prepare an absorbent resin having an average particle size of 150 to 850 占 퐉.

Comparative Example  2

A superabsorbent resin was prepared in the same manner as in Comparative Example 1 except that 8 g of water was used instead of 10 g of water. The water content of the hydrogel polymer formed in this process was 45% by weight. The average particle diameter of the prepared superabsorbent resin was 150 to 850 탆.

Comparative Example  3

A superabsorbent resin was prepared in the same manner as in Comparative Example 1, except that 5 g of water was used instead of 10 g of water. The water content of the hydrogel polymer formed in this process was 40% by weight. This method was also followed by secondary drying under the same conditions as in Comparative Example 1, as the polymer adhered to the apparatus at the time of pulverization. The average particle diameter of the prepared superabsorbent resin was 150 to 850 탆.

Test Example : Evaluation of water content and physical properties of superabsorbent resin

Test Example  1: Moisture content evaluation

The water content of the water absorbent resin according to the above Examples and Comparative Examples was measured by the following method, and the results are shown in Table 1.

1 g of each of the water absorbent resin powders was placed in a drier using infrared ray (IR), dried at 180 ° C for 40 minutes, and water content was measured.

Test Example  2: Property evaluation

In order to evaluate the physical properties of the super absorbent resin of the examples and the resin of the comparative examples, the following tests were conducted.

The physical properties of the superabsorbent resin and the surface cross-linked superabsorbent resin according to Examples 1 to 3 and Comparative Examples 1 to 3 were measured by the following methods. The physical properties were measured in the manner recommended by EDANA.

1. Water content: 1 g of the superabsorbent resin powder before surface cross-linking was placed in a drier using IR (infrared ray), dried at 180 ° C for 40 minutes, and then the water content was measured.

2. Water retention capacity: 0.2 g of the superabsorbent resin powder before or after the surface cross-linking was put into a tea bag, sedimented and absorbed in 0.9% saline solution for 30 minutes, dehydrated for 3 minutes with 250 g of centrifugal force, And the amount was measured (measured by the weight change of the sample).

3. Water component: 1 g of the superabsorbent resin powder before or after the surface cross-linking was put in a 250 ml Erlenmeyer flask and eluted in 200 ml of 0.9% saline solution for 18 hours. Thereafter, the gel portion of the superabsorbent resin was filtered with filter paper No. 4, and only the portion dissolved in the 0.9% saline solution was analyzed to determine the weight ratio of the superabsorbent resin eluted to the superabsorbent resin before elution And the water content was measured (see EDANA 270.2 method)

4. Absorption Under Pressure (AUP): measured by the EDANA WSP 242.2 method.

The physical properties of the superabsorbent resin before and after crosslinking of the surfaces of Examples 1 to 3 and Comparative Examples 1 to 3 measured by the above-mentioned methods are summarized in Table 1 below.

Properties before surface crosslinking Properties after surface cross-linking Moisture content
(weight%) Function
(g / g) For water
ingredient
(weight%) Moisture content
(weight%) Function
(g / g) For water
ingredient
(weight%) Example 1 30 43.5 15.7 36.5 14.2 25.3 Example 2 27 44.0 16.8 36.4 13.8 26.1 Example 3 25 45.1 17.2 36.6 13.0 26.4 Comparative Example 1 50 43.2 19.2 34.1 16.2 25.9 Comparative Example 2 45 45.1 15.2 36.1 14.1 25.6 Comparative Example 3 40 40.3 13.8 35.1 12.9 26.8

From the results shown in Table 1, it can be seen that Examples 1 to 3 exhibit physical properties equal to or higher than those of Comparative Examples 1 to 3, and that the drying efficiency is enhanced by using a relatively low water content functional gel polymer (drying time is shortened ).

100: Production apparatus of superabsorbent resin
10: Mixer 20: Monomer composition supply part
30: Belt type polymerization reactor
32, 34: rotating shaft 36: belt
40: Function gel polymer sheet 42: Cropped hydrogel polymer
50: cutter 52: cutting means
60, 62: drying device

Claims (16)

Forming a monomer composition comprising a water-soluble ethylenically unsaturated monomer and a polymerization initiator;
Introducing the monomer composition into a polymerization reactor and conducting drying in a polymerization reactor while progressing polymerization to form a hydrogel polymer having a water content of 30 wt% or less; And
Cutting and crushing the hydrogel polymer,
The monomer composition is introduced at a constant rate so that the hydrogel polymer formed in the polymerization reactor maintains a thickness of 0.1 cm to 2.0 cm,
Wherein said polymerization comprises UV polymerization at a temperature of 25 to < RTI ID = 0.0 > 150 C < / RTI &
The drying is carried out by infrared irradiation, hot air drying, microwave irradiation or ultraviolet irradiation by a drying device installed in a polymerization reactor or connected to a polymerization reactor,
Further comprising a step of surface-crosslinking the ground particles after the step of cutting and pulverizing the hydrogel polymer, followed by surface treatment, drying or surface treatment after drying,
Wherein the water-repellent ability after surface cross-linking is 13.0 to 14.2 (g / g), and the water content after surface cross-linking is 25.3 to 26.1 wt%. delete The method of producing a superabsorbent resin according to claim 1, wherein the water content of the hydrogel polymer is 20 to 30% by weight. The method of claim 1, wherein the polymerization reactor comprises a continuous or discontinuous moving conveyor belt. delete delete The method of producing a superabsorbent resin according to claim 1, wherein the monomer composition further comprises a crosslinking agent. The water-soluble ethylenically unsaturated monomer according to claim 1, wherein the water-
(Meth) acryloyl ethane sulfonic acid, 2- (meth) acryloyl propane sulfonic acid, and 2- (meth) acryloyl ethane sulfonic acid, ) Anionic monomers of acrylamido-2-methylpropanesulfonic acid and its salts;
(Meth) acrylamide, N-substituted (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, methoxypolyethylene glycol Non-ionic hydrophilic-containing monomer of (meth) acrylate; And
Is at least one selected from the group consisting of unsaturated monomers containing an amino group of (N, N) -dimethylaminoethyl (meth) acrylate and (N, N) -dimethylaminopropyl (meth) A method for producing a superabsorbent resin. The method of producing a superabsorbent resin according to claim 1, wherein the concentration of the water-soluble ethylenically unsaturated monomer is 20 to 60 wt%. 8. The thermosetting resin composition according to claim 7, wherein the crosslinking agent is a water-soluble substituent of an ethylenically unsaturated monomer, a crosslinking agent having at least one ethylenic unsaturated group and at least one functional group capable of reacting with a water-soluble substituent of an ethylenically unsaturated monomer, And
A water-soluble substituent of an ethylenically unsaturated monomer, a crosslinking agent having at least two functional groups capable of reacting with a water-soluble substituent formed by hydrolysis of a vinyl monomer, and a mixture thereof. Gt; The method according to claim 1, wherein the polymerization initiator is at least one selected from the group consisting of an azo initiator, a peroxide initiator, a redox initiator, an organic halide initiator, acetophenone, benzoin, benzophenone, benzyl and derivatives thereof By weight based on the total weight of the resin. The method of manufacturing a superabsorbent resin according to claim 1, wherein the pulverization is performed by any one of a pulverizing apparatus selected from the group consisting of a pin mill, a hammer mill, a screw mill and a roll mill. The method for producing a superabsorbent resin according to claim 1, wherein in the step of cutting and pulverizing, a powdery resin having an average particle size of 150 to 850 탆 is formed. delete The method for producing a superabsorbent resin according to claim 1, wherein the drying after the surface treatment is carried out by natural drying, infrared irradiation, hot air drying, microwave irradiation or ultraviolet irradiation. The method of producing a superabsorbent resin according to claim 1, wherein the water content after drying is 2 to 15 wt%.

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