KR102438035B1 - Preparation method of super absorbent polymer with improved moisture content and additive water control system for the same - Google Patents

Abstract

The present invention provides a method for effectively manufacturing a superabsorbent polymer with an improved water content and a method for effectively producing a superabsorbent polymer with an improved water content and minimizing agglomeration or agglomeration of the superabsorbent polymer in the reactor by forming uniform droplets of an optimized size by the vibrator hole method and adding water to the superabsorbent polymer A singer system for augmentation is provided.

Description

Method for manufacturing superabsorbent polymer with improved moisture content and watering system

The present invention relates to a method for producing a superabsorbent polymer with improved water content, and to a watering system for increasing the water content of the superabsorbent polymer.

Super Absorbent Polymer (SAP) is a synthetic polymer material that can absorb water 500 to 1,000 times its own weight. Material), etc., are named differently. In addition to hygiene products such as paper diapers for children/adults and women's sanitary napkins, the superabsorbent polymer as described above is used as a soil repair agent for gardening, water-repellent material for civil engineering and construction, a sheet for seedlings, a freshness maintenance agent in the food distribution field, and as a material for poultice. It is widely used.

There are various methods of producing such a superabsorbent polymer, but after a polymerization process of heat or light crosslinking, the water contained in the resin is evaporated, and after pulverizing to an appropriate size, the surface at a temperature of 100 ^o C to 200 ^o C going through a cross-linking process. In the repeated high-temperature process, the moisture of the polymerized resin is reduced to a level of about 0.2% to about 0.3%.

In particular, the polymerized superabsorbent polymer has a low moisture content through drying/pulverization, so fine particles are easily blown away during handling, making it difficult to handle. In order to solve this problem, it is necessary to improve the moisture content through the water adder. In general, when water is added with large water droplets, the superabsorbent polymer particles agglomerate and a coarse is formed. There is a problem in that lumps such as lumps are formed.

Accordingly, there is a demand for the development of a technology for a super absorbent polymer, a superabsorbent polymer having excellent processability and physical properties, and a method for manufacturing the same, since it is possible to uniformly function without agglomeration and lump formation of the superabsorbent polymer particles.

An object of the present invention is to provide a method of manufacturing a superabsorbent polymer with improved water content by forming uniform water droplets of an optimized size using a vibrator hole method and adding water.

Another object of the present invention is to provide an oscillator hole-type singer system for increasing the moisture content of the superabsorbent polymer.

The present invention provides a method for producing a superabsorbent polymer, comprising the step of dropwise adding droplets to superabsorbent polymer particles using an oscillator hole-type water system.

The present invention also provides a liquid supply unit including at least one vibrator for forming droplets; and a droplet injection plate having two or more holes having a diameter of 10 μm to 4000 μm, which is disposed at the lower end of the liquid supply unit.

In the present invention, terms such as first, second, third, etc. are used to describe various components, and the terms are used only for the purpose of distinguishing one component from other components.

The terminology used herein is used to describe exemplary embodiments only, and is not intended to limit the present invention.

The singular expression includes the plural expression unless the context clearly dictates otherwise.

In this specification, terms such as "comprises", "comprising" or "having" are intended to describe embodied features, numbers, steps, components, or combinations thereof, and include one or more other features, numbers, or steps. , components, combinations or additions thereof are not excluded.

Also in this specification, when it is said that each layer or element is formed "on" or "over" each layer or element, it means that each layer or element is formed directly on each layer or element, or other It means that a layer or element may additionally be formed between each layer, on the object, on the substrate.

For reference, in the present specification, "part by weight" means a relative concept in which the weight of the other material is expressed as a ratio based on the weight of a certain material. For example, in a mixture in which the weight of material A is 50 g, material B is 20 g, and material C is 30 g, the amounts of material B and material C are each 40 parts by weight based on 100 parts by weight of material A parts by weight and 60 parts by weight.

Meanwhile, “% by weight” means an absolute concept in which the weight of a certain material is expressed as a percentage among the total weight. In the mixture exemplified above, the content of material A, material B, and material C in 100% of the total weight of the mixture is 50% by weight, 20% by weight, and 30% by weight, respectively.

Since the present invention may have various modifications and various forms, specific embodiments will be illustrated and described in detail below. However, this is not intended to limit the present invention to the specific disclosed form, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Hereinafter, a method for producing a superabsorbent polymer having an improved water content according to the present invention and a watering system for increasing the water content of the superabsorbent polymer will be described in detail.

<Method for producing super absorbent polymer>

According to one aspect of the present invention, there is provided a method for producing a superabsorbent polymer, comprising the step of dropwise adding droplets to the superabsorbent polymer particles using an oscillator hole-type water system.

As used herein, the term “polymer” or “polymer” refers to a polymerized state of a water-soluble ethylenically unsaturated monomer, and may cover all water content ranges or particle diameter ranges. Among the above polymers, a polymer having a water content (moisture content) of about 40% by weight or more in a state before drying after polymerization may be referred to as a hydrogel polymer, and particles obtained by drying and pulverizing the hydrogel polymer may be referred to as a crosslinked polymer. have.

In addition, the "base resin" is a polymer obtained by drying and pulverizing a polymer in which a water-soluble ethylenically unsaturated monomer is polymerized to form a powder, wherein the water-soluble ethylenically unsaturated monomer is polymerized and crosslinked by an internal crosslinking agent. ) is a collection of That is, the base resin refers to a powder form made of cross-linked polymer particles in a state in which the surface modification or surface cross-linking step to be described later is not performed. Accordingly, "crosslinking the surface of the base resin" means crosslinking the surface of each of the crosslinked polymer particles constituting the base resin.

In addition, "super absorbent polymer" means the polymer or the base resin itself, depending on the context, or an additional process for the polymer or the base resin, such as surface crosslinking, fine powder reassembly, drying, grinding, classification, etc. It is used to encompass all of the products that have undergone the process and are in a state suitable for commercialization.

As a result of continuous experiments by the present inventors, a vibration-type water system capable of controlling the size of water droplets was manufactured to be used in a hole method in the conventional nozzle method, and uniform droplets of an optimized size were formed, thereby preventing agglomeration or high absorption in the reactor. The invention was completed after confirming that a superabsorbent polymer resin having a high moisture content can be manufactured and provided by minimizing the formation of agglomerates of the resin and reducing processability.

The method for producing a superabsorbent polymer with improved water content according to the present invention is characterized in that it includes the step of dropwise adding droplets to an oscillator hole-type water system as will be described later.

In the present invention, the watering system is characterized in that it includes a liquid supply unit including one or more vibrators for producing uniform droplets and a plate to which water is ejected.

Specifically, the water system includes a liquid supply unit including one or more vibrators for forming droplets, and a droplet injection plate disposed at the lower end of the liquid supply unit and provided with two or more holes having a diameter of 10 μm to 4000 μm. will include

The liquid injection plate may have a hole in it according to the total flow rate to be used. For example, the flow rate range that can be formed per hole may be set according to the diameter of the hole, and the number of holes may be increased in order to increase the amount of water. The specific number of holes and the configuration of the vibrator in the singer system, and the configuration of the liquid supply unit and the plate will be described later.

In the present invention, the weight ratio of water to be hydrolyzed relative to 100 parts by weight of the total weight of the superabsorbent polymer particles may be 0.1 parts by weight to 50 parts by weight, or 0.5 parts by weight to 45 parts by weight, or 1 part by weight to 40 parts by weight. However, in terms of increasing the moisture content, the valence weight ratio is preferably 1.5 to 30 parts by weight.

In particular, if the weight ratio of water added to the superabsorbent polymer particles is less than the above range, an effect of increasing the water content cannot be expected, and a large amount of fine powder is generated during the process, which is not preferable. In addition, when the weight ratio of water added to the superabsorbent polymer particles is greater than the above range, the viscosity of the resin surface increases and irreversible agglomeration occurs between the superabsorbent polymer particles, so that the processability of the resin is improved. As it falls, the particle size changes, which may cause a problem that it is difficult to use as a product.

According to the present invention, by forming uniform droplets of an optimized size with an oscillator hole-type water system that can effectively control the size of droplets, agglomeration in the reactor or formation of agglomerates of superabsorbent resin is minimized and processability is reduced by about 0.5 weight % or more, or about 0.5% to about 10% by weight, or about 1% by weight or more, or about 1% to about 10% by weight, or about 1% to about 5% by weight of a superabsorbent polymer having a high moisture content effectively can be manufactured.

On the other hand, in the manufacturing process of the superabsorbent polymer, water is a polymerization medium and is used in various ways, such as to facilitate dispersion of the crosslinking solution in the surface crosslinking process. In addition, the residual moisture in the final product acts as an antistatic agent and plasticizer for the resin, suppressing the formation of very small superabsorbent polymer dust in the application process and preventing the pulverization of the superabsorbent polymer particle. However, in general, when water is added even in a small amount to the superabsorbent polymer, the stickiness of the resin surface increases due to the water absorbed on the surface, and irreversible agglomeration between the superabsorbent polymer particles occurs. do.

Such an increase in viscosity and agglomeration reduces processability, such as an increase in load in manufacturing and application processes, and consequently causes an increase in the particle size of the superabsorbent polymer, a decrease in physical properties, and a decrease in productivity.

In the present invention, the water content is increased by adding water droplets of a size optimized to the superabsorbent polymer to the superabsorbent polymer, thereby minimizing physical damage to the superabsorbent polymer and satisfying high water content and high processability at the same time. When water is added to the superabsorbent polymer, it becomes possible to function uniformly without caking. Therefore, when the superabsorbent polymer prepared in this way is applied to final products such as diapers, it has the advantage of minimizing deterioration of physical properties due to, for example, physical crushing of the superabsorbent polymer due to compression or strong air transport during the diaper production process. .

The superabsorbent polymer may include a base resin powder comprising a first crosslinked polymer of a water-soluble ethylenically unsaturated monomer having at least a partially neutralized acidic group; and a surface crosslinking layer formed on the base resin powder and including a second crosslinked polymer in which the first crosslinked polymer is further crosslinked through a surface crosslinking agent.

The size of the superabsorbent polymer particles is 10 micrometers (micrometers, μm) to 850 (micormeters, μm), or 10 μm to 850 μm, or 50 to 850 μm.

On the other hand, the present invention is a water-soluble ethylenically unsaturated monomer having an acidic group at least partially neutralized, an encapsulated foaming agent, an inorganic foaming agent, an anionic surfactant, and a monomer composition comprising a polymerization initiator by thermal polymerization or photopolymerization to obtain a hydrogel polymer. forming; drying the hydrogel polymer; pulverizing the dried polymer; and subjecting the pulverized polymer to a surface crosslinking reaction.

The superabsorbent polymer obtained according to the above-mentioned manufacturing method maintains excellent absorption performance such as water holding capacity and absorbency under pressure, and satisfies improved liquid permeability and absorption rate, etc., thereby satisfying all physical properties of one embodiment, Sanitary materials such as diapers, in particular, an ultra-thin hygiene material having a reduced pulp content may be suitably used.

<Singer system for manufacturing superabsorbent polymer>

According to another aspect of the present invention, there is provided a watering system for increasing the moisture content of the super absorbent polymer.

As a result of continuous experiments of the present inventors, by applying the hole method, not the conventional nozzle method, to increase the moisture content of the superabsorbent polymer, a vibration-type hydrous system that can effectively control the uniform droplet size is applied, thereby preventing agglomeration or high water content in the reactor. The invention was completed after confirming that a superabsorbent polymer resin having a high water content can be manufactured and provided while minimizing the formation of agglomerates of the water absorbent resin and reducing processability.

Specifically, according to the present invention, the liquid supply unit including at least one vibrator for forming droplets; and a droplet injection plate disposed at the lower end of the liquid supply unit and provided with two or more holes having a diameter of 10 μm to 4000 μm.

In the present invention, the watering system refers to a device for effectively adding droplets to the superabsorbent polymer particles for increasing the moisture content of the superabsorbent polymer.

In particular, the watering system is characterized in that it includes a liquid supply unit including one or more vibrators for producing uniform droplets, and a plate through which water is ejected.

For example, the singer system may be formed in a form in which the liquid supply unit and the droplet injection plate are integrated. For example, it may be configured as an integrated device by applying a droplet injection plate to the lower end of the liquid supply unit.

As another example, in the singer system, the liquid supply unit and the droplet injection plate may be formed as separate devices. For example, the liquid supply unit and the droplet injection plate may be connected to each other or configured as separate devices rather than an integrated type. In this case, since it is possible to detach and replace the droplet injection plate, flow rate expansion is easy, and cleaning is easy when contamination occurs.

For example, as shown in FIG. 1, the water system includes a water tank 2 corresponding to a liquid supply unit including one or more vibrators 1 for producing uniform droplets and a hole plate 3 for spraying droplets. it could be Here, the vibrator 1 may be coupled to the water tank 2 for liquid supply through a separate connection part 4 .

In addition, the liquid injection plate can be processed according to the total flow rate to be used. For example, a flow rate range that can be formed per hole may be set according to the diameter of the hole, and the number of holes may be increased in order to increase the amount of water.

Specifically, the diameter of the hole in the plate may be 10 μm to 4000 μm, or 10 μm to 2000 μm, or 15 μm to 1500 μm, or 20 μm to 1000 μm. However, it is preferable that the diameter of the hole is 20 μm to 500 μm, which is appropriate in terms of increasing the moisture content.

For example, in the liquid injection plate, as shown in FIG. 2 , the arrangement of two or more holes 3a included in the droplet injection hole plate 3 is determined such that the distance L between the holes is the diameter of the hole. It can be configured based on (D).

The distance (L) between the holes in the plate may be arranged to be about 5 times or more, about 5.2 times or more, or about 5.5 times or more based on the aforementioned hole diameter (D). The distance L between the holes may maintain the minimum distance as described above in order to induce droplet fall without overlap in consideration of the size of the generated droplet. The upper limit of the distance L between the holes is not particularly limited, but may be arranged to be about 100 times or less, or about 80 times or less, or about 60 times or less, if necessary.

In addition, the number of holes in the plate is 200 or more, or 200 to 50X10 ⁶ , or 400 or more, or 400 to 25X10 ⁶ , or 2X10 ⁵ or more, or 2X10 ⁵ to 1 m ² based on the total plate area It can be 20X10 ⁶ pieces.

Meanwhile, in the addition system, the liquid supply unit generates a frequency of 20 Hz to 8000 Hz from the vibrator to form droplets. For example, a frequency of 500 Hz to 5000 Hz, or 1000 Hz to 4000 Hz generated from the vibrator may be applied to the flowing liquid. However, in terms of increasing the moisture content, the frequency is preferably 1500 Hz to 3500 Hz.

Specifically, in the liquid supply of the singer system of the present invention, the droplet generation principle is to transfer vibrations of a specific frequency generated in a vibrator to which an alternating current is applied to a fluid flowing at a specific speed to change them into droplets. This is different from the mesh vibrators used in mist generating equipment using ultrasonic waves to generate small droplets by applying ultrasonic vibrations to a stationary liquid mass, it is characterized by delivering vibrations of a specific frequency to the flowing fluid. do.

In addition, the method of flowing the liquid to generate droplets from the liquid supply part is not particularly limited, and the connection part 4 connected to the liquid supply water tank 2 as shown in FIG. 1 is a part through which the liquid flows. can The velocity of the liquid flowing into the flowing liquid applied during the droplet generation is also not particularly limited, but it is applicable by selecting an appropriate range from a velocity greater than 0 m/s, which is not in a stationary state.

In addition, in the water system, it can be configured by setting the thickness of a plate in which a plurality of holes are formed so that a large amount of water can be stably contained in the system by supporting the load of water supplied from the outside, and water droplets can be uniformly sprayed. The thickness of the plate may be 0.1 mm to 20 mm, or 0.1 mm to 10 mm, or 0.1 mm to 8 mm, preferably 0.2 mm to 5 mm.

The liquid injection plate may be made of one or more selected from the group consisting of stainless steel, ceramic, copper, polycarbonate, and polyacrylate. Here, the ceramic is a non-metal solid material made using natural raw materials such as clay, or, for example, one or more materials selected from the group consisting of alumina (Al ₂ O ₃ ), silicon oxide (SiO ₂ ), magnesia (MgO), and the like. It is a non-metallic solid material containing However, in terms of increasing the moisture content, the plate is preferably made of stainless steel.

On the other hand, the singer system of the present invention may be configured in a form in which a skeleton is additionally provided at the lower end of the hole plate for droplet injection. Here, the skeleton can be said to be a component introduced to supplement the load applied to the hole plate. In the above water system, when the amount of water is increased, the hole ratio in the plate is increased and the flow rate is increased, the thin hole plate is a support for reinforcing enough to withstand the load of water.

In addition, the water supply system of the present invention further includes a gasket part or a cushioning material part in at least one of between the liquid supply unit and the droplet injection plate and between the droplet injection plate and the bone aggregate. You may.

In addition, the plate may be treated with a super water-repellent coating on the surface on which water is sprayed to prevent water droplets or SAP particles from adhering to the plate (plate) during the water soaking, wetness, or scattering. For example, the super water-repellent coating layer in the plate may have a contact angle with water of 100 ^o or more, preferably 120 ^o or more, more preferably 150 ^o or more. In addition, the super water-repellent coating layer is one selected from the group consisting of polypropylene resin, fluoro resin (Teflon, Teflon), acrylate resin, polyurethane resin, silicone material, silicone lubricant, and fluorine lubricant. It may include more than one. In addition, the super water-repellent coating layer may further include inorganic particles such as silica, preferably hydrophobized silica. In order to block contamination by SAP, it is preferable that the plate be treated with super water-repellent coating with polypropylene and silica.

For example, the thickness of the super water-repellent coating layer may be 0.01 mm to 5 mm, or 0.01 mm to 1 mm, or 0.01 mm to 0.5 mm, preferably 0.02 mm to 0.1 mm.

On the other hand, the size of the water droplets formed in the water system may be 10 um to 8000 um. For example, the droplet size may be 100 um to 4000 um, or 200 um to 1000 um. In particular, if the size of the water droplet to be hydrolyzed is too small, the water droplet is blown up by the sweep air inside the reactor and adheres to the reactor wall, and SAP particles stick to this part, and lumps and lumps may be formed. For example, when the average flow velocity of the airflow near the water heater is about 0.25 m/s, a droplet size of 300 μm or more is desirable. However, if the size of the water droplet is too large, when the water droplet falls on the superabsorbent polymer particles, the particles absorb moisture around the water droplet and agglomerates may form, so a droplet size of 1000 μm or less is preferable. Here, the size of the droplet corresponds to the diameter of the droplet, and specifically refers to the diameter of the major axis. In addition, the airflow (sweep air) inside the reactor refers to an airflow introduced and discharged into the equipment to cool the high-temperature polymerized SAP. The size of the droplet that can fall stably is determined by the airflow velocity. In particular, if the internal airflow is not controlled quickly, the occurrence of lumps due to fine powder may be reduced, but the overall process efficiency related to the manufacture of the superabsorbent polymer may be reduced accordingly.

According to the present invention, the high-temperature superabsorbent polymer particles produced through the polymerization process are placed at the lower end of the hydrolysis system, and uniform droplets are added dropwise to the superabsorbent polymer particles through the hydrolysis system, thereby forming a lump inside the reactor. ) and superabsorbent polymer particles do not agglomerate, and products with high moisture content can be effectively manufactured.

In addition, the superabsorbent polymer produced by applying the above-described hydrous system maintains excellent absorption performance such as water holding capacity and absorbency under pressure, and satisfies the improved liquid permeability and absorption rate, etc. and sanitary materials such as diapers, in particular, an ultra-thin sanitary material having a reduced pulp content may be appropriately used.

According to the present invention, it is possible to effectively manufacture a superabsorbent polymer with an improved moisture content while minimizing agglomeration in the reactor or formation of agglomerates of the superabsorbent polymer by forming and adding water droplets of an optimized size by the vibrator hole method.

1 is a schematic diagram illustrating an irrigation system for increasing the water content of a superabsorbent polymer according to an embodiment of the present invention (1: vibrator, 2: water tank for liquid supply, 3: hole plate for droplet injection, 4 : Connection between vibrator and water tank).
2 is a schematic diagram illustrating an exemplary droplet injection plate included in the singer system according to an embodiment of the present invention (3: hole plate for droplet injection, 3a: hole, L: gap between holes, D: diameter of the hole).

Hereinafter, through specific examples of the invention, the operation and effect of the invention will be described in more detail. However, these embodiments are merely presented as an example of the invention, and the scope of the invention is not defined thereby.

[Example]

Preparation Example: Preparation of super absorbent polymer

A solution of 11 g of IRGACURE 819 initiator diluted to 0.5% in acrylic acid (110 ppm based on the monomer composition) and 28 g of polyethylene glycol diacrylate (PEGDA, molecular weight 400) diluted to 5% in acrylic acid (solution A) prepared. Then, a solution (B solution) obtained by diluting trimethylolpropane triacrylate (Ethoxylated-TMPTA, TMP(EO)9TA, M-3190 Miwon Specialty Chemical Co., Ltd.) containing ethylene oxide at 9 mol% in acrylic acid to 5% prepared.

480 g of acrylic acid was injected into a 2L glass reactor surrounded by a jacket in which a heating medium pre-cooled to 25° C. was circulated, and 37 g of the A solution and 14 g of the B solution were respectively injected. Then, in the glass reactor, 700 g (solution C) of a 24% caustic soda solution was slowly added dropwise and mixed. When the C solution was added dropwise, the temperature of the mixed solution increased to about 72° C. or higher by the heat of neutralization, and the mixed solution was waited for cooling. The degree of neutralization of acrylic acid in the thus obtained mixed solution was about 70 mol%.

In addition, a solution (E-1 solution) was prepared by dissolving 28 g of a sodium persulfate solution diluted to 4% in water. In addition, as a surfactant, 6.7 g (E-2 solution) of a DOSS (Dioctyl sodium sulfonate) solution diluted to 4% in water was prepared.

Then, after confirming that the temperature of the mixed solution rises to 80° C. or higher by the heat of neutralization, wait for the temperature to cool to 40° C., and when the reaction temperature reaches 40° C., the mixed solution prepared in advance E-1 solution and E-2 solution were injected.

Then, the mixed solution prepared above was poured into a vat-type tray (tray, 15 cm in width × 15 cm in length) installed in a square polymerization reactor equipped with a light irradiation device on the top and preheated to 80°C. Then, the mixed solution was irradiated with light. It was confirmed that a gel was formed on the surface after about 20 seconds from the light irradiation, and it was confirmed that the polymerization reaction occurred simultaneously with the foaming about 30 seconds after the light irradiation. Thereafter, the polymerization reaction was further performed for 2 minutes, the polymerized sheet was taken out and cut to a size of 3 cm × 3 cm. Then, the cut sheet was prepared as a crumb through a chopping process using a meat chopper.

Then, the crumb was dried in an oven capable of transferring air volume up and down. To ensure that the moisture content of the dried powder is about 2% or less, hot air at 180° C. is flowed from the bottom to the top for 15 minutes, and then flows from the top to the bottom for 15 minutes to dry the powder uniformly. did it

The dried powder was pulverized with a grinder and classified to obtain a base resin having a particle size of 50 μm to 850 μm.

Then, 100 g of the base resin was mixed with a crosslinking agent solution in which 3 g of water, 3 g of methanol, 0.4 g of ethylene carbonate, and 0.5 g of Aerosil 200 (aerosil 200, EVONIK) were mixed, and then surface cross-linked at 190°C for 30 minutes. made a reaction Then, the obtained product was pulverized to obtain a surface-crosslinked superabsorbent polymer having a particle diameter of 10 to 850 μm.

After the surface crosslinking process, the moisture content was 0.2% or less.

Example 1: Preparation of super absorbent polymer with increased moisture content

The high-temperature superabsorbent polymer particles were cooled in a continuous paddle mixer and added at 2000 kg/h, the resin residence time in the mixer was about 30 minutes, and the hydrolyzed resin was recovered at the end of the mixer and the physical properties were evaluated. At the upper end of the mixer, a vibrator hall type singer system as shown in FIG. 1 is provided, and a frequency of 2750 Hz is applied to the vibrator with 417 holes having a diameter of 200 μm through the adder system to have a diameter of about 400 μm, about 390 μm to about 390 μm. Water droplets with a size of 410 μm were made, and the water was added for 24 hours at an amount of water of 100 kg/h. At this time, water corresponding to 5.0% by weight of the superabsorbent polymer was added.

The water system was applied to a plate with a thickness of 0.3 mm made of stainless steel in the same manner as shown in FIG. 2 , with holes having a diameter of 200 μm, 125× ^{10 5} per 1 m ² based on the total plate area. The hole plate was arranged such that the gap (L) between the holes was 5 to 7 times the diameter (D, 200 μm) of the holes. In addition, the hole plate further includes a super water-repellent coating layer having a contact angle with water of about 150 ^o or more, and the super water-repellent coating layer was to include polypropylene and hydrophobized silica.

Example 2: Preparation of super absorbent polymer with increased moisture content

In Example 1, a frequency of 2750 Hz was applied to the vibrator with 250 200 μm-diameter holes through the vibrator hole-type hydrous system in Example 1 to form water droplets with a diameter of about 400 μm and a size of about 390 μm to 410 μm, with a water content of 60 kg/h. The singer proceeded for hours. At this time, the superabsorbent polymer of Example 2 was prepared in the same manner as in Example 1, except that water corresponding to 3.0 wt% of the superabsorbent polymer was added.

Example 3: Preparation of super absorbent polymer with increased moisture content

Example 1 was carried out in the same manner as in Example 1, except that water droplets having a diameter of about 40 μm were formed and added to the vibrator by applying a frequency of 2750 Hz to the vibrator with 4170 holes having a diameter of 20 μm through the oscillator hole method in Example 1 A super absorbent polymer of Example 3 was prepared.

Comparative Example 1

In Example 1, while adding superabsorbent polymer particles at 2000 kg/h, water was sprayed with five spray nozzles having an average nozzle diameter of 400 μm, and water was added at 100 kg/h, except for the difference with Example 1 A super absorbent polymer of Comparative Example 1 was prepared in the same manner.

Comparative Example 2

In Example 1, while injecting the super absorbent polymer particles at 2000 kg/h, water droplets with a diameter of about 4000 μm and a size of about 3990 μm to 4010 μm were formed through a hole-type hydrolysis system with 166 holes having a diameter of 1 mm, and 100 kg/ A superabsorbent polymer of Comparative Example 1 was prepared in the same manner as in Example 1, except that hydrogenation was performed in h.

The specific hydrous system method and droplet size (diameter, um) applied to the hydrolysis step of the Examples and Comparative Examples, and the hydrous weight ratio (%) to the total weight of the superabsorbent polymer are as shown in Table 1 below.

singer system Water-repellent coating of hall plate
Whether Droplet size (㎛) SAP Ready
singer weight
ratio
(%) method hall size
(μm) number of holes
(dog_total area) frequency
(Hz) Example 1 vibrator
Hall way 200 417 2750 O 400 5 Example 2 vibrator
Hall way 200 250 2750 O 400 3 Example 3 vibrator
Hall way 20 4170 2750 O 40 5 Comparative Example 1 spray
Nozzle method -
(Nozzle thickness: average 400㎛) - - X wide distribution 5 Comparative Example 2 Hall way 1000 166 - O 4000 5

Experimental Example: Evaluation of physical properties of super absorbent polymer

For the superabsorbent polymers of Examples and Comparative Examples prepared above, each physical property was evaluated by the following method.

(1) Measurement of moisture content

5 g of the superabsorbent polymer particles of Examples and Comparative Examples were sampled and the weight change was measured by heating and drying at 160 ^o C for 30 minutes to calculate the moisture content (% by weight), which was repeated 3 times to obtain an average value.

(2) evaluation of lump formation

It was checked whether or not lumps were formed inside the reactor after hydrolysis. The recovered resin was classified with a sieve, and it was confirmed whether plate-shaped lumps having an area of 1 cm ² or more were formed in a planar view.

(3) Evaluation of agglomeration inside the reactor

The recovered resin was classified with a sieve, and the presence or absence of agglomeration of superabsorbent polymer particles with a diameter of about 2.0 mm or more was confirmed.

The results of the superabsorbent polymers of Examples and Comparative Examples measured by the above-described method are shown in Table 2 below.

Average moisture content (wt%) Lump formation Absence of agglomeration inside the reactor Example 1 3 X X Example 2 2 X X Example 3 2 X X Comparative Example 1 2 O O Comparative Example 2 0.3 O O

Referring to Table 2, the embodiments of the present invention form uniform water droplets with an optimized size through an oscillator hole-type water system that can effectively control the droplet size, thereby forming lumps and superabsorbent polymers in the reactor. It was confirmed that the water content of the superabsorbent polymer could be increased to about 2 wt % to about 3 wt % without causing agglomeration of the particles.

On the other hand, it was confirmed that Comparative Example 1 of the spray nozzle method and Comparative Example 2 of the spray hole method had a problem in that the watering step could not be performed for a long period of time due to the formation of lumps and aggregation inside the reactor.

1: Oscillator
2: Water tank for liquid supply
3: Hole plate for droplet injection
4: Connection between the vibrator and the water tank
3a: hole
L: gap between holes
D: diameter of hole

Claims (10)

Comprising the step of dropwise adding to the superabsorbent polymer particles with an oscillator hole-type water system,
A method for producing a super absorbent polymer.
The method of claim 1,
The singer system,
a liquid supply unit including at least one vibrator for forming droplets; and
a droplet injection plate disposed at a lower end of the liquid supply unit and provided with two or more holes having a diameter of 10 μm to 4000 μm;
which includes,
A method for producing a super absorbent polymer.
According to claim 1,
The valence weight ratio is 0.1 parts by weight to 50 parts by weight with respect to 100 parts by weight of the total weight of the superabsorbent polymer particles,
A method for producing a super absorbent polymer.
According to claim 1,
The superabsorbent polymer may include a base resin powder comprising a first crosslinked polymer of a water-soluble ethylenically unsaturated monomer having at least a partially neutralized acidic group; and a surface cross-linking layer formed on the base resin powder, wherein the first cross-linked polymer comprises a second cross-linked polymer further cross-linked via a surface cross-linking agent.
A method for producing a super absorbent polymer.
According to claim 1,
The size of the superabsorbent polymer particles is 10 μm to 850 μm,
A method for producing a super absorbent polymer.
a liquid supply unit including at least one vibrator for forming droplets; and
a droplet injection plate disposed at a lower end of the liquid supply unit and provided with two or more holes having a diameter of 10 μm to 4000 μm;
A water system for producing a superabsorbent polymer comprising a.
7. The method of claim 6,
The distance (L) between the holes in the plate is 5 times or more based on the hole diameter (D),
Hydrogen system for the manufacture of superabsorbent polymers.
7. The method of claim 6,
Forming droplets by applying vibration of a frequency of 20 Hz to 8000 Hz generated from the vibrator,
Hydrogen system for the manufacture of superabsorbent polymers.
7. The method of claim 6,
The plate has a thickness of 0.1 mm to 20 mm,
Hydrogen system for the manufacture of superabsorbent polymers.
7. The method of claim 6,
The plate is made of one or more selected from the group consisting of stainless steel, copper, ceramic, polycarbonate, and polyacrylate,
Hydrogen system for the manufacture of superabsorbent polymers.

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