KR20170096322A - Manufacturing Method For Recombine Products Of Super Absorbent Polymer Fines - Google Patents

Abstract

The present invention relates to a method for producing a superabsorbent fine particulate reassembly. More specifically, the present invention relates to a method for producing a reassembly with high strength, by breaking down cross-linkage selectively on fine particles which had undergoing a surface treatment process. According to the present invention, it is possible to produce superabsorbent fine particulate reassemblies having high cohesiveness for fine particles through an easy reassembly process, and also to produce superabsorbent resins containing the same.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a superabsorbent polymer composition,

The present invention relates to a method for producing a superabsorbent fine particle disassembly, and more particularly, to a method for producing a reassembly having excellent dense and cohesive strength by decomposing crosslinking selectively only fine particles which have undergone a surface treatment process .

Super Absorbent Polymer (SAP) is a synthetic polymer material capable of absorbing moisture from about 500 to 1,000 times its own weight. As a result, it is possible to use SAM (Super Absorbent Material), AGM Material), and so on. The superabsorbent resin as described above has been put to practical use as a sanitary article and is currently being used in various fields such as a sanitary article such as a diaper for children, a soil remover for gardening, an index material for civil engineering and construction, a sheet for seedling exploitation, And has been widely used as a material for various purposes.

The absorption mechanism of the superabsorbent resin is based on the interaction between the permeation pressure due to the difference in electrical attraction represented by the charge of the polymer electrolyte, the affinity between water and the polymer electrolyte, and the molecular expansion due to the repulsion between polymer electrolyte ions and the expansion inhibition due to crosslinking . That is, the absorbency of the superabsorbent resin depends on the aforementioned affinity and molecular expansion, and the rate of absorption depends on the permeation pressure of the absorbent polymer itself.

As a method for 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 Patent Application Laid-open No. 56-161408, Japanese Patent Application Laid-Open No. 57-158209, and Japanese Patent Application Laid-open No. 57-198714. A heat polymerization method in which a hydrogel polymer is polymerized while being broken and cooled, and a photopolymerization method in which a high concentration aqueous solution is irradiated with ultraviolet rays or the like on a conveyor belt to perform polymerization and drying at the same time.

Japanese Patent Application Laid-Open No. 2004-250689 discloses a method of 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 a superabsorbent resin in which a water-soluble ethylenically unsaturated monomer having a crosslinking agent is polymerized by irradiation with ultraviolet rays in the presence of a peroxide and a radical photopolymerization initiator having a benzoyl group.

The hydrogel polymer obtained through the above polymerization reaction is subjected to a drying and a pulverization step to obtain a powder, and the surface is treated to prepare a superabsorbent resin. The surface treatment process is usually carried out by a surface cross-linking reaction in which a solution containing a surface cross-linking agent is sprayed onto the powder, which may cause non-uniformity of the surface treatment liquid distribution due to the difference in surface area due to the particle size distribution of the powder. Therefore, in order to minimize such nonuniformity, before the surface treatment step, the pulverized powder is classified according to the particle size. Normal particles having a particle size of 150 to 850 탆 are selected and subjected to a surface treatment, .

However, in the process of manufacturing a superabsorbent resin, fine particles having a particle size of less than 150 μm are inevitably generated. Particularly, the fine particles (referred to as 'base resin fine particles' in this specification) formed in the above- However, this method induces non-uniform polymerization or scatters light to interfere with polymerization and acts as a factor of lowering the physical properties of the product.

In order to solve this problem, there has been developed a method of re-assembling fine particles having a particle size of 150 to 850 탆 by mixing a fine powder and water at a certain ratio by using a separate re-granulator, but in the case of such a fine powder compact, , There is a problem that the amount of fine powder is increased compared with the case of the normal polymer because it is easily broken in the pulverization process of the hydrogel polymer.

On the other hand, since the fine powder (referred to as 'product fine powder' in the present specification) generated in the step of surface-treating normal particles having a normal particle size distribution (150 to 850 μm) is strongly crosslinked on the surface, There is still a problem that the physical properties of the fine pulverized product are deteriorated due to the weak cohesive force between the base resin fine powder and the product fine powder and the water that mediates them.

In order to solve this problem, Korean Patent Laid-Open Publication No. 2015-0032045 discloses a technique of treating a base resin with a basic solution in a process of mixing and reassembling a fine powder of a base resin and a product fine, It is a fact that is demanded.

Korean Patent Laid-Open Publication No. 2015-0032045 "Method for producing superabsorbent resin"

Accordingly, the inventors of the present invention have conducted various studies, and after decomposing the crosslinked bonds in the surface treatment process by basic treatment of only the fine particles of the product, the cohesive force between the base resin fine powder and the product fine powder, It is possible to produce the improved superabsorbent fine powder disassembly, thereby completing the present invention.

Accordingly, an object of the present invention is to provide a method of manufacturing a superabsorbent fine particle dispersion assembly in which the properties of a fine resinous assembly are improved by reassembling a base resin fine powder and a product fine powder.

Another object of the present invention is to provide a method for producing a superabsorbent resin by mixing a superabsorbent finely divided powder aggregate having enhanced physical properties with a hydrogel polymer in a drying and pulverizing step after the polymerization process.

In order to achieve the above object, the present invention provides a process for producing a water-soluble ethylenically unsaturated polymer, comprising the steps of: i) drying and pulverizing a hydrogel polymer which is a water-soluble ethylenically unsaturated polymer; Ii) classifying the pulverized particles into base resin fine particles having a particle size of less than 150 탆, normal particles having a size of 150 탆 or more and 850 탆 or less, and large particles having a diameter exceeding 850 탆; Iii) surface treating the normal particles having a particle size of 150 μm or more and 850 μm or less; Iv) selecting a product fine having a particle size of less than 150 mu m generated in the surface treatment process and treating the fine product with a basic solution; And (v) mixing the basic treated product fine with the base resin fine powder in step (ii) and reassembling the same.

The present invention also provides a method for producing a superabsorbent resin by mixing a fine particle remover produced by the above method with a hydrogel polymer in a drying and pulverizing step after the polymerization process.

According to the present invention, a superabsorbent fine particle aggregate having a high fine aggregation strength and a superabsorbent resin containing the same can be produced through an easy reassembling process.

1 is a Scanning Electron Microscope (SEM) image of a superabsorbent fine powder disassembly according to Example 1 of the present invention.
2 is a Scanning Electron Microscope (SEM) image of a superabsorbent fine powder disassembly according to Comparative Example 1 of the present invention.
3 is a Scanning Electron Microscope (SEM) image of a superabsorbent fine powder disassembly according to Comparative Example 2 of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

The method of manufacturing a superabsorbent fine powder mill according to the present invention is a method of manufacturing a superabsorbent fine powder mill according to the present invention by mixing a fine powder (base resin fine powder) not subjected to a surface treatment and a fine powder (product fine powder) To an additive.

More specifically,

I) drying and grinding the hydrogel polymer as a water-soluble ethylenically unsaturated polymer;

Ii) classifying the pulverized particles into base resin fine particles having a particle size of less than 150 탆, normal particles having a size of 150 탆 or more and 850 탆 or less, and large particles having a diameter exceeding 850 탆;

Iii) surface treating the normal particles having a particle size of 150 μm or more and 850 μm or less;

Iv) selecting a product fine having a particle size of less than 150 mu m generated in the surface treatment process and treating the fine product with a basic solution; And

V) re-assembling the basic treated product fine with the base resin fine powder of step ii);

And a control unit.

The term "superabsorbent resin particles" used in the present invention refers to dried and pulverized hydrogel polymers. More specifically, the hydrogel polymer is a solid jelly-like material having a size of 1 cm or more, which has been polymerized and contains a large amount of water (50% or more). The hydrogel polymer is dried and then cut and pulverized to obtain a powder Superabsorbent resin particles. The hydrogel polymer thus corresponds to the intermediate state of the process.

However, fines having a particle size of less than about 150 탆 are inevitably generated in the pulverization process in which the hydrogel polymer is dried and then cut and pulverized, and a fine powder having a particle size of less than 150 탆 is generated even after the surface treatment process. Application of the superabsorbent polymer particles prepared including these fine particles to a product is undesirable in absorbent sanitary articles because it can deteriorate physical properties.

Therefore, it is important to eliminate the fine particles in the final resin product, or to re-assemble the fine particles so as to have a normal particle size.

Therefore, the present invention is characterized in that only the fine particles (product fine particles) that have undergone the surface treatment process are subjected to a basic additive treatment to decompose the crosslinking, and then the unfaced fine particles (base resin fine particles) To produce an assembly.

Hereinafter, steps of polymerization, drying, crushing, classification, surface treatment, basic treatment, and pulverization and reassembly for producing a superabsorbent resin will be described in detail before describing the method for producing a superabsorbent fine pulverizer according to the present invention .

Hydrogel  Drying and crushing of polymer

The hydrogel polymer according to the present invention may be a product of a polymerization reaction of a monomer composition comprising a water-soluble ethylenically unsaturated monomer and a polymerization initiator, and may be represented by the following formula (1).

[Chemical Formula 1]

R ¹ -COOM ¹

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

For example, the water-soluble ethylenically unsaturated monomer is not particularly limited as long as it is a monomer usually used in the production of a superabsorbent resin, but preferably an anionic monomer and a salt thereof, a nonionic hydrophilic monomer and an amino group-containing unsaturated monomer, Cargo, and cargo. Specific examples thereof include acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, 2-acryloylethanesulfonic acid, 2- methacryloylethanesulfonic acid, 2- (meth) acryloylpropanesulfonic acid, 2- Anionic monomers of (meth) acrylamido-2-methylpropanesulfonic acid and its salts; (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; Unsaturated monomers containing amino groups of (N, N) -dimethylaminoethyl (meth) acrylate or (N, N) -dimethylaminopropyl (meth) acrylamide and quaternary products thereof; And a combination thereof. More preferably, acrylic acid or a salt thereof can be used. When acrylic acid or a salt thereof is used as a monomer, there is an advantage that a superabsorbent resin having improved water absorption can be obtained.

The polymerization initiator may be a thermal polymerization initiator or a photopolymerization initiator depending on the polymerization method. However, even with the photopolymerization method, a certain amount of heat is generated by ultraviolet irradiation or the like, and a certain amount of heat is generated as the polymerization reaction, which is an exothermic reaction, proceeds. .

As the thermal polymerization initiator, at least one selected from the group consisting of a persulfate-based initiator, an azo-based initiator, hydrogen peroxide and ascorbic acid may be used. Specifically, examples of the persulfate-based initiator include sodium persulfate, potassium persulfate, and ammonium persulfate. Examples of the azo initiator include azo compounds such as 2,2-azobis- (2-amidinopropane) dicarboxylic acid, 2,2-azobis- (N, N-dimethylene) isobutyraldehyde dihydrochloride, 2- Carbamoyl azo) isobutyronitrile, 2,2-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, 4,4-azobis- (4-cyanovaleric acid ) May be used.

On the other hand, as the photo polymerization initiator, at least one selected from the group consisting of benzoin ether, dialkyl acetophenone, hydroxyl alkyl ketone, phenyl glyoxylate, benzyl dimethyl ketal, acylphosphine and alpha-amino ketone can be used . As an example of the acylphosphine, commercially available lucirin TPO, i.e., 2,4,6-trimethyl-benzoyl-trimethylphosphine oxide can be used.

The use amount of the polymerization initiator is preferably about 0.001 to about 0.5 part by weight based on 100 parts by weight of the water-soluble ethylenically unsaturated monomer. If the amount of the polymerization initiator is less than 0.001 part by weight, the conversion rate is low, and the remaining monomer may be extracted in a large amount in the final product. If the amount is more than 0.5 part by weight, the chain of the polymer forming the network becomes short and the molecular weight of the superabsorbent resin is small The physical properties may be uneven, which is not preferable.

The method of polymerizing and cross-linking the monomer composition comprising the water-soluble ethylenically unsaturated monomer and the polymerization initiator to form the hydrogel polymer is applicable without limitation of the constitution as long as it is a conventional polymerization method in the technical field of the present invention. For example, the polymerization method may be divided into thermal polymerization and photo-polymerization depending on the type of polymerization energy source. In the case of thermal polymerization, the polymerization may proceed in a reactor having a stirring axis such as a Kneader, And may proceed in a reactor equipped with a movable conveyor belt when it is advanced.

According to one embodiment of the present invention, the hydrogel polymer can be obtained by introducing the monomer composition into a reactor such as a kneader provided with a stirring shaft and supplying hot air thereto or by heating the reactor to heat-polymerize. At this time, the hydrogel polymer discharged to the reactor outlet depending on the shape of the stirring shaft provided in the reactor can be obtained as particles of several millimeters to several centimeters. For example, 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 usually 2 to 50 mm can be obtained.

According to another embodiment of the present invention, when the photopolymerization is carried out on the monomer composition in a reactor equipped with a movable conveyor belt, a hydrogel polymer on a sheet (hereinafter referred to as a 'polymer sheet') can be obtained. At this time, the thickness of the polymer 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 ensure the production rate, a polymer sheet having a thickness of usually 0.5 to 5 cm Is preferably obtained.

At this time, the water content of the hydrogel polymer may be 30 to 80% by weight, preferably 40 to 60% by weight. It is preferable that the water content of the thus formed polymer is included in the above range in view of optimizing the efficiency in a drying step to be described later.

The hydrogel polymer immediately after the polymerization is subjected to a drying step, which may be carried out at a temperature of 150 to 250 ° C. If the drying temperature is lower than 150 ° C, the drying time may become longer and the physical properties of the final superabsorbent resin may be lowered. If the drying temperature is higher than 250 ° C, only the surface of the hydrogel polymer is dried, Can be increased. Therefore, the drying temperature may be 150 to 250 ° C, more preferably 160 to 200 ° C. In this case, the drying time is not particularly limited, but may be carried out at the drying temperature for 20 to 90 minutes in consideration of process efficiency and the like.

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

Such a drying step may be carried out such that the water content of the dried polymer (hereinafter referred to as "base resin") is 0.05 to 5 parts by weight. That is, when the water content of the base resin is less than 0.05 part by weight, the manufacturing cost increase due to excessive drying and the decomposition of the cross-linking polymer may occur, which is not advantageous. When the water content of the base resin exceeds 5 parts by weight, it is preferable that the water content of the base resin is included in the above range in consideration of the occurrence of defects in the subsequent step.

The drying step may be followed by a step of pulverizing the base resin, wherein the pulverizing step is a step for optimizing the surface area of the base resin so that the particle size of the pulverized base resin is 150 or more and 850 占 퐉 or less .

Meanwhile, in order to increase the efficiency of the drying step, the method of manufacturing the SAP according to the present invention may further include a step of simply grinding before the drying step, if necessary. The step of simply grinding before the drying step may be carried out such that the particle size of the polymer of the superabsorbent resin particles is 1 to 15 mm. However, pulverization of the polymer particles having a particle size of less than 1 mm is technically And further, there may be a phenomenon of agglomeration among the pulverized particles, and when the pulverization is carried out so that the particle size exceeds 15 mm, the efficiency increase effect in the subsequent drying step becomes insignificant.

The pulverizer to be used at this time is not limited in its constitution, but may be a vertical pulverizer, a turbo cutter, a turbo grinder, a rotary cutter mill, And a grinding machine group consisting of a cutter mill, a disc mill, a shred crusher, a crusher, a chopper and a disc cutter. However, the present invention is not limited to the above-described examples.

Thereafter, in the method for producing a superabsorbent resin according to the present invention, after the above-mentioned drying step, the base resin is pulverized to obtain superabsorbent resin particles. The particle size of the superabsorbent resin particles obtained after the pulverization step is 150 to 850 탆. In the method for producing a superabsorbent resin according to the present invention, the pulverizer used for pulverizing to such a particle size is specifically a pin mill, a hammer mill, a screw mill, a roll mill A roll mill, a disc mill or a jog mill may be used, but the present invention is not limited thereto.

Classification

According to the present invention, the step of classifying the polymer powder obtained through the above-described process into fine particles having a particle size of less than 150 μm, normal particles having a particle size of 150 to 850 μm, and large particles having a particle size larger than 850 μm are carried out. This is a step that can be further carried out to manage the physical properties of the superabsorbent resin powder to be finally produced, and a base resin having a particle diameter within the above range can be used as a classifier.

For example, a sieve having a scale of a mesh size, in particular, a sieve having a size of 850 탆 (20 mesh) and 150 탆 (100 mesh ) Can be applied.

Specifically, the preparation process of the classification step will be described in detail. The particles of the superabsorbent resin supplied from the polymer feeder are pulverized in a polymer grinder at a particle size of 150 to 850 μm, and classified through a classifier according to each particle size. At this time, the fine particles having a particle size of less than 150 占 퐉 are not separately classified, but particles having a particle size exceeding 850 占 퐉 can be separately classified and returned to the mill.

At this time, large particles having a particle size exceeding 850 mu m generated in the classification process are re-pulverized, and again, as in step ii), the particles having a particle size of less than 150 mu m, By mass), can be performed. It is preferable that this re-pulverization process is repeated until large particles having a particle size exceeding 850 mu m disappear to secure normal particles.

Surface treatment

Meanwhile, in the step of surface treatment in the present invention, the surface cross-linking reaction may proceed using a surface cross-linking solution containing a certain component.

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 near 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.

According to a preferred embodiment, the surface cross-linking solution of the present invention comprises a surface cross-linking agent and a solvent, more specifically, the surface cross-linking solution is a C2 to C8 diol or glycol compound; The solvent includes water and an alcohol or a glycol-based organic solvent. The surface of the base resin having the normal particle size of 150 to 850 mu m in particle size can be treated with the surface crosslinking solution having the above composition. Preferably, the surface cross-linking solution comprises 0.1 to 20% by weight of a surface cross-linking agent, 10 to 70% by weight of an organic solvent, and a residual amount of water.

Examples of the surface cross-linking agent include 1,3-propanediol, 2,3,4-trimethyl-1,3-pentanediol, 2-butene-1,4-diol, 1,4-butanediol, Diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polyoxypropylene glycol, polyoxypropylene glycol, polyoxyethylene Propylene glycol, glycerol, polyglycerol, and combinations thereof. More preferably, 1,3-propanediol may be used as the surface cross-linking agent, and propylene glycol may also be used. In the present invention, when two or more surface cross-linking agents are used in combination, the mixing weight ratio thereof may be from 2: 8 to 8: 2, based on the weight of the total surface cross-linking agent.

Wherein the organic solvent is selected from the group consisting of ethanol, methanol, isopropyl alcohol, ethylene glycol, propylene glycol, polyethylene glycol, ethylene glycol diglycidyl ether, polypropylene glycol, n-propanol, butanol, propanediol, One or more species can be used.

The surface cross-linking solution may be sprayed through a pipe or a nozzle, but it is preferably sprayed onto the surface of the normal particle through a nozzle. The surface cross-linking solution is sprayed at a temperature of 120 to 300 DEG C for 10 to 120 minutes, preferably 20 to 90 minutes The surface of the normal particle is preferably subjected to a crosslinking reaction.

After the surface cross-linking reaction and before the classifying step to be described later, it may further include a usual drying process, and the conditions are not limited.

When the surface cross-linking reaction is completed, the product is further classified by classifying it into fine particles having a particle size of less than 150 μm, normal particles having a size of 150 μm or more and 850 μm or less, or large particles having a particle size exceeding 850 μm . Product differentials of less than 150 microns in particle size are then sorted and stored for subsequent treatment with a basic solution.

Basic treatment

In the surface treatment process, product fine particles having a particle size of less than 150 μm are generated, and they are selectively treated with a basic solution to decompose the crosslinking formed in the surface treatment of the product fine particles. That is, as a basic solution capable of reacting with a carboxylic acid formed from the formula (1), at least one solution selected from the group consisting of NaOH, KOH, Na ₂ CO ₃ , NaHCO ₃ and combinations thereof at a concentration of 1 to 10 wt% Can be used. It is preferable that the basic solution is sprayed or immersed in the product fine powder at a temperature of 60 to 200 ° C for 30 seconds to 10 minutes.

Reassembling the differential

In the process of re-assembling the fine powder according to the present invention, the re-assembly process can be performed in a wet state having a water content of about 30 to 60% in order to increase the cohesive strength. For example, the polymer in the form of a finely divided powder may be sprayed with water or put into a bulk to mix the fine powder with water while stirring. At this time, the higher the moisture content of the fine particles, the higher the cohesive strength of the fine particles, but the larger the re-assembly mass of the re-assembly process or the larger the moisture content, the more the solidified mass of the re-assembly is formed On the other hand, if the water content is low, the reassembling process is easy, but the cohesive strength is low, so that it is often broken down again as a fine powder after reassembly.

It is preferable that the weight ratio of the product fine powder to the base resin fine powder is 1: 9 to 9: 1 to be reassembled, and the water content is 50 to 100 parts by weight, based on 100 parts by weight of the sum of the total weight of the base resin fine powder and the product fine powder. 200 parts by weight of water may be mixed and wetted.

At this time, moisture can be supplied in the form of mist or spray for more uniform mixing. For example, in the wetting process, the fine powder is supplied to at least one powder feeder or hopper while spraying a predetermined amount of water uniformly onto the fine powder using at least one spray nozzle Or the like.

Thereafter, a further step of drying the re-assembled fine powder may be performed, wherein the drying temperature of the drying step may be about 150 to 250 ° C. If the drying temperature is lower than 150 ° C, the drying time becomes excessively long and the physical properties of the ultrafine superabsorbent resin finally formed may be lowered. If 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 be carried out at a temperature of about 150 to 250 ° C, more preferably about 160 to 200 ° 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. The water content of the re-assembled derivative after such a drying step may be about 0.05 to about 10% by weight.

At this time, if necessary, a step of simply grinding may be further performed before drying in order to increase the efficiency of the drying step. In this case, the pulverizer to be used 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 crusher, a chopper, and a disc cutter. The crusher includes a crusher, a crusher, a crusher, a disc mill, a disc mill, a shred crusher, a crusher, a chopper and a disc cutter. However, the present invention is not limited to the above-described example. In this case, the pulverization step may be coarsely pulverized so that the particle size of the re-assembled fine powder is about 1 to about 15 mm.

The re-assembled fine powder may further be pulverized or classified to have a particle size of about 150 to 850 탆. The pulverizer used for pulverizing the re-assembled fine powder may be a pin mill, a hammer mill, a screw mill, a roll mill, a disc mill Or a jog mill may be used. However, the present invention is not limited to the above-mentioned examples.

Superabsorbent  Resin Manufacturing

It is preferable that the superabsorbent resin particles comprising the fine pulverulent remainder include the fine pulverized material in an amount of 50% by weight or less based on the total weight.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to examples. However, the embodiments according to the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The embodiments of the present invention are provided to enable those skilled in the art to more fully understand the present invention.

Production Example 1 Production of superabsorbent polymer fine powder

100 g of acrylic acid, 0.5 g of polyethylene glycol diacrylate as a crosslinking agent, 38.9 g of caustic soda (NaOH) and 103.9 g of water were mixed to prepare a monomer composition having a monomer concentration of 50% by weight. Then, 0.01 g of Irgacure 651 (2,2-dimethoxy-1,2-di (phenyl) ethanone) and 0.3 g of sodium persulfate were added to the monomer composition, and the mixture was supplied through a rotating belt polymerizer and irradiated with ultraviolet rays . Polymerization was started within 1 minute after irradiating ultraviolet rays, and polymerization was continued for 5 minutes. At this time, the internal temperature of the reactor was adjusted to be 80 to 99 ° C.

The polymerized superabsorbent polymer was transferred and cut with a cutter. Thereafter, the polymer discharged from the cutter was dried in a hot-air drier at 180 캜 for 1 hour. Next, after crushing with a pin mill, the mixture was classified into a base resin fine powder having particle sizes of less than 150 mu m, a normal particle size of not less than 150 mu m and not more than 850 mu m, and large particles exceeding 850 mu m using a sieve . At this time, large particles exceeding 850 mu m were recycled to the pulverizer, and base resin fine particles less than 150 mu m were separately discharged and stored.

A surface cross-linking solution containing 5% by weight of 1,3-propanediol, 5% by weight of propylene glycol and water in a residual amount was sprayed onto a base resin having a particle size of not less than 150 μm and not more than 850 μm classified into a normal particle size, The surface of the resin was treated. Further, in the step of treating the surface, the classified functional gel polymer was fed to one surface cross-linking reactor and the surface cross-linking reaction of the hydrogel polymer was carried out at a temperature of 190 DEG C or higher for 20 minutes to 50 minutes each.

After the surface treatment, the product was further classified into fine particles having particle sizes of less than 150 mu m, products having a size of 150 mu m or more and 850 mu m or less, and large particles having a size exceeding 850 mu m using a sieve. In this process, large particles exceeding 850 μm were re-pulverized, and product differentiations of less than 150 μm were stored separately.

≪ Example 1 >

600 g of the product fine powder produced in the course of preparing the superabsorbent polymer was put into a planetary mixer of 40 L capacity. At this time, an aqueous solution containing 5 wt% of sodium hydroxide (NaOH) was added to the same amount of water heated to 80 DEG C by setting the chopper of the mixer at 1500 rpm and the impeller at 60 rpm, followed by stirring for 30 seconds. After the stirring, 1400 g of the base resin differential was put into a planetary mixer. At this time, the chopper of the mixer was set at 1500 rpm, the impeller was set at 60 rpm, and the same amount of water was added thereto, followed by stirring for 60 seconds to prepare a superabsorbent fine granulation product.

≪ Comparative Example 1 &

2000 g of a fine powder mixture obtained by mixing the product fine powder and the base resin fine powder produced in the process of preparing the superabsorbent polymer was put into a 40 L capacity planetary mixer. At this time, the chopper of the mixer was set to 1500 rpm, the impeller was set to 60 rpm, and the same amount of water heated to 80 캜 was added thereto, followed by stirring for 60 seconds to prepare a fine powder compact.

≪ Comparative Example 2 &

A fine pulverized material was obtained by proceeding in the same manner as in Comparative Example 1, except that 6 wt% of sodium hydroxide was used instead of water added to make the fine pulverized material.

Table 1 below shows the concentration of NaOH treatment and the successive re-assembly (two-stage re-assembly) of the above-described Example 1 and Comparative Examples 1 and 2. Figs. 1 to 3 show the results of the comparison between Example 1 of the present invention and Comparative Example 1 is a scanning electron microscope (SEM) image of a superabsorbent fine powder disassembly according to the present invention.

division NaOH concentration (wt%) Whether to reassemble the 2nd stage Example 1 5 O Comparative Example 1 0 X Comparative Example 2 6 X

In Example 1, only the product fine was selectively treated with NaOH to decompose the surface cross-linking, and then reassembled with the base resin fine powder (two-step reassembly) was performed. As a result, the porous structure was densely aggregated to visually confirm that the cohesive strength and the density were improved.

On the other hand, in Comparative Example 1, the product fine powder and the base resin fine powder were reassembled without NaOH treatment. In Comparative Example 2, the product fine powder and the base resin fine powder were mixed and then re-assembled by NaOH treatment. As shown in FIG. 3, the porous structure was present as it was, and the cohesive strength and compactness were confirmed to be weaker than those of Example 1.

Claims (9)

In a method of manufacturing a superabsorbent fine powder disassembly,
I) drying and grinding the hydrogel polymer as a water-soluble ethylenically unsaturated polymer;
Ii) classifying the pulverized particles into base resin fine particles having a particle size of less than 150 탆, normal particles having a size of 150 탆 or more and 850 탆 or less, and large particles having a diameter exceeding 850 탆;
Iii) surface treating the normal particles having a particle size of 150 μm or more and 850 μm or less;
Iv) selecting a product fine having a particle size of less than 150 mu m generated in the surface treatment process and treating the fine product with a basic solution; And
V) re-assembling the basic treated product fine with the base resin fine powder of step ii);
≪ RTI ID = 0.0 > 11. < / RTI >
The method according to claim 1,
Wherein the surface treatment of step (iii) comprises treating the surface of the stationary particle with a surface cross-linking solution comprising a surface crosslinking agent, an organic solvent and water, which is a diol or a glycol compound of C2 to C8 .
3. The method of claim 2,
Wherein the surface cross-linking solution comprises 0.1 to 20% by weight of a surface cross-linking agent, 10 to 70% by weight of an organic solvent and water in a remaining amount.
3. The method of claim 2,
Wherein the organic solvent is selected from the group consisting of ethanol, methanol, isopropyl alcohol, ethylene glycol, propylene glycol, polyethylene glycol, ethylene glycol diglycidyl ether, polypropylene glycol, n-propanol, butanol, propanediol, Wherein the superabsorbent powder is one type.
The method according to claim 1,
Wherein the surface treatment of step iii) comprises cross-linking the surface of the stationary particle for 20 to 90 minutes at a temperature of 120 to 300 ° C.
The method according to claim 1,
Wherein the basic solution in step iv) is one kind of solution selected from the group consisting of NaOH, KOH, Na ₂ CO ₃ , NaHCO ₃ and combinations thereof in a concentration of 1 to 10% by weight. Way.
The method according to claim 1,
Wherein the weight ratio of the product fine powder to the base resin fine powder in the step (v) is 1: 9 to 9: 1 and is reassembled.
A process for producing a superabsorbent resin characterized by mixing the fine pulverulent re-assembly produced by the method of any one of claims 1 to 7 with the functional gel-like polymer of step (i) of claim 1.
9. The method of claim 8,
Wherein the superabsorbent resin contains the fine pulverized material in an amount of 50% by weight or less.

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