WO2015084059A1 - Method for preparing super absorbent resin - Google Patents

Abstract

The present invention relates to a method for preparing a super absorbent resin comprising the steps of: a) thermally polymerizing or photopolymerizing a monomer composition, which contains water soluble ethylene-based unsaturated monomers and a polymerization initiator, to prepare a hydrous gel polymer; b) drying the hydrous gel polymer; c) grinding the dried hydrous gel polymer; d) adding particles and a surface crosslinking agent having the following properties of i) and ii) to the ground hydrous gel polymer; and e) performing a surface crosslinking reaction. i) BET specific surface area of 300 to 1500 m²/g, ii) porosity of 50% or higher

Description

Manufacturing method of super absorbent polymer

The present invention relates to a method for producing a super absorbent polymer, and more particularly, to a method for preparing a super absorbent polymer in which superhydrophobic microparticles are introduced onto a superabsorbent polymer.

Superabsorbent Polymers (SAPs) are synthetic polymer materials capable of absorbing water up to 500 to 1000 times its own weight. In addition to sanitary products such as sanitary sanitary materials, it is widely used as a material for horticultural soil repair, civil engineering, building index material, seedling sheet, freshness maintaining agent in food distribution field, and steaming.

In the manufacturing process of such a super absorbent 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. The residual moisture in the final product also acts as an antistatic and plasticizer for the resin, inhibiting the formation of very small superabsorbent resin dust in the application process and preventing the grinding of SAPs particles. In general, however, even if a small amount of the superabsorbent polymer is added, the viscosity of the resin surface increases due to the water absorbed on the surface, and irreversible agglomeration occurs between the superabsorbent polymer particles. do. This increase in viscosity and agglomeration reduce processability, such as an increase in load in manufacturing and application processes, resulting in an increase in the particle size of the superabsorbent polymer, a decrease in physical properties, and a decrease in productivity. Until now, research on super absorbent polymers has mainly focused on the polymerization process and the improvement of the absorbency thereof, and the surface crosslinking for increasing the surface properties of the superabsorbent polymers or the pressurized absorbent capacity. In order to solve some problems such as anti-caking during storage, studies on surface properties have been conducted.

In this regard, in the related art, Korean Patent Laid-Open Publication No. 2012-0081113 discloses a method of manufacturing an absorbent resin including water-insoluble inorganic fine particles, but such a method is disclosed.

According to the prior art, when the moisture on the surface of the super absorbent polymer increases, the viscosity of the surface increases, causing problems such as the above-mentioned agglomeration, workability, and a decrease in productivity, resulting in high water content and high processability. There is a need for development of a satisfactory superabsorbent polymer.

The present invention is to solve the problems of the prior art as described above,

By modifying the surface of the superabsorbent polymer to hydrophobicity to reduce the viscosity and cohesion due to water absorption, it is easy to reduce the load in the manufacturing process and increase the particle size and physical properties by increasing the workability, and to satisfy the high water content and high processability at the same time Accordingly, an object of the present invention is to provide a method for preparing a superabsorbent polymer having porous superhydrophobic microparticles capable of minimizing physical property degradation due to resin damage in an application process.

The present invention to achieve the above object,

a) preparing a hydrogel polymer by thermally polymerizing or photopolymerizing a monomer composition comprising a water-soluble ethylenically unsaturated monomer and a polymerization initiator; b) drying the hydrogel polymer; c) grinding the dried hydrogel polymer; d) adding particles and a surface crosslinking agent having the properties of i) to ii) to the pulverized hydrogel polymer; And e) provides a method for producing a super absorbent polymer comprising the step of performing a surface crosslinking reaction.

i) a BET specific surface area of 300 to 1500 m ² / g,

ii) porosity of at least 50%

According to the manufacturing method of the superabsorbent polymer according to the present invention, by modifying the surface of the superabsorbent polymer hydrophobic to reduce the viscosity and cohesion due to the absorption of water, to reduce the load and control the particle size and physical properties in the manufacturing process by increasing the workability By facilitating and satisfying a high water content and a high processability at the same time, there is an advantage that the physical property degradation due to resin breakage in the application process can be minimized.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

Method for producing a super absorbent polymer according to the present invention,

a) preparing a hydrogel polymer by thermally polymerizing or photopolymerizing a monomer composition comprising a water-soluble ethylenically unsaturated monomer and a polymerization initiator; b) drying the hydrogel polymer; c) grinding the dried hydrogel polymer; d) adding particles and a surface crosslinking agent having the properties of i) to ii) to the pulverized hydrogel polymer; And e) performing a surface crosslinking reaction.

i) a BET specific surface area of 300 to 1500 m ² / g,

ii) porosity of at least 50%

First, the method for preparing a super absorbent polymer according to the present invention is a) undergoing a step of preparing a hydrogel polymer by thermal polymerization or photopolymerization of a monomer composition comprising a water-soluble ethylenically unsaturated monomer and a polymerization initiator.

For preparing the super absorbent polymer of the present invention, the polymer may be prepared by the steps and methods commonly used in the art. Specifically, in the preparation of the super absorbent polymer of the present invention, the monomer composition includes a polymerization initiator, the photopolymerization initiator is included in the photopolymerization method according to the polymerization method, and the thermal polymerization is performed in the thermal polymerization method. Initiator and the like. However, even with the photopolymerization method, since a certain amount of heat is generated by irradiation such as ultraviolet irradiation, and a certain amount of heat is generated in accordance with the progress of the polymerization reaction, which is an exothermic reaction, a thermal polymerization initiator may be additionally included.

The thermal polymerization initiator used in the method for preparing the superabsorbent polymer according to the present invention is not particularly limited, and preferably at least one selected from the group consisting of an initiator group consisting of persulfate-based initiator, azo-based initiator, hydrogen peroxide, and ascorbic acid. Can be used. Specifically, examples of persulfate-based initiators include sodium persulfate (Na2S2O8), potassium persulfate (K2S2O8), ammonium persulfate (NH4) 2S2O8, and the like. Examples of initiators include 2, 2-azobis- (2-amidinopropane) dihydrochloride (2, 2-azobis (2-amidinopropane) dihydrochloride), 2, 2-azobis- (N, N-dimethylene) Isobutyramidine dihydrochloride (2,2-azobis- (N, N-dimethylene) isobutyramidine dihydrochloride), 2- (carbamoyl azo) isobutyronitrile (2- (carbamoylazo) isobutylonitril), 2,2-azo Bis [2- (2-imidazolin-2-yl) propane] dihydrochloride (2,2-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride), 4,4-azobis- (4-cyanovaleric acid) (4,4-azobis- (4-cyanovaleric acid)) etc. can be used.

In addition, the photopolymerization initiator used in the method for preparing the superabsorbent polymer according to the present invention is not particularly limited, but is preferably benzoin ether, dialkyl acetophenone, or hydroxyl alkyl ketone. At least one selected from the group consisting of alkylketone, phenyl glyoxylate, benzyl dimethyl ketal, acyl phosphine and alpha-aminoketone can be used. . Meanwhile, as an example of acylphosphine, a commercially available lucirin TPO, that is, 2,4,6-trimethyl-benzoyl-trimethyl phosphine oxide can be used. .

In addition, in the manufacturing method of the superabsorbent polymer according to the present invention, the water-soluble ethylenically unsaturated monomer is not particularly limited as long as it is a monomer normally used in the preparation of the superabsorbent polymer, but preferably an anionic monomer and salts thereof, Any one or more selected from the group consisting of ionic hydrophilic-containing monomers, amino group-containing unsaturated monomers and quaternized compounds thereof can be used. Specifically, acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, 2-acryloylethanesulfonic acid, 2-methacryloylethanesulfonic acid, 2- (meth) acryloylpropanesulfonic acid, or 2 Anionic monomers of-(meth) acrylamide-2-methylpropane sulfonic acid and salts thereof; (Meth) acrylamide, N-substituted (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, methoxy polyethylene glycol (meth) acrylate or polyethylene glycol ( Nonionic hydrophilic-containing monomers of meth) acrylate; And an amino group-containing unsaturated monomer of (N, N) -dimethylaminoethyl (meth) acrylate or (N, N) -dimethylaminopropyl (meth) acrylamide and a quaternized product thereof. It can be used easily, and more preferably acrylic acid or salts thereof may be used. In the case of using acrylic acid or salts thereof as a monomer, there is an advantage in that a super absorbent polymer having improved water absorption can be obtained.

In the method for preparing a super absorbent polymer according to the present invention, the monomer composition may include a predetermined amount of fine powder, that is, a polymer or resin powder having a particle size of less than 150 μm, in the prepared superabsorbent polymer powder for the effect of resource recycling. In detail, specifically, the polymer or resin powder having the particle size of less than 150 μm may be added at the initial, middle, and end stages before the start of the polymerization reaction of the monomer composition or after the start of the polymerization reaction. In this case, the amount that can be added is not limited, but it is preferable to add 1 to 10 parts by weight based on 100 parts by weight of the monomer included in the monomer resin composition in order to prevent the deterioration of physical properties of the superabsorbent polymer.

On the other hand, in the method for producing a super absorbent polymer according to the present invention, the concentration of the water-soluble ethylenically unsaturated monomer in the monomer composition may be appropriately selected in consideration of the polymerization time and reaction conditions, but preferably 40 to 55% by weight. You can do When the concentration of the water-soluble ethylenically unsaturated monomer is less than 40% by weight, it is disadvantageous in terms of economy, and when it exceeds 55% by weight, the grinding efficiency may be low when the polymerized hydrous gel polymer is pulverized.

The method of preparing a hydrogel polymer by thermally polymerizing or photopolymerizing such a monomer composition is not limited as long as it is a polymerization method that is commonly used. Specifically, the polymerization method is largely divided into thermal polymerization and photopolymerization according to the polymerization energy source, when the thermal polymerization is usually carried out, it can be carried out in a reactor having a stirring shaft, such as kneader, and when the polymerization proceeds, Although it can proceed in a reactor with a conveyor belt possible, the above-described polymerization method is an example, the present invention is not limited to the above-described polymerization method.

For example, the hydrogel polymer obtained by supplying hot air to a reactor such as a kneader having a stirring shaft as described above or by heating the reactor to be thermally polymerized has a reactor outlet according to the shape of the stirring shaft provided in the reactor. The hydrogel polymer discharged into may be in the form of several centimeters to several millimeters. Specifically, the size of the hydrous gel polymer obtained may vary depending on the concentration and the injection speed of the monomer composition to be injected, the hydrogel polymer having a particle size of 2 to 50 mm can be obtained.

In addition, when photopolymerization is carried out in a reactor having a movable conveyor belt as described above, the form of the hydrogel polymer generally obtained may be a hydrogel gel polymer on a sheet having a width of the belt. At this time, the thickness of the polymer sheet depends on the concentration and the injection speed of the monomer composition to be injected, but it is preferable to supply the monomer composition so that a polymer on a sheet having a thickness of 0.5 to 5 cm can be obtained. When the monomer composition is supplied to such an extent that the thickness of the polymer on the sheet is too thin, it is not preferable because the production efficiency is low, and when the thickness of the polymer on the sheet exceeds 5 cm, the polymerization reaction does not occur evenly over the entire thickness. You may not.

Thereafter, the method for preparing a super absorbent polymer according to the present invention is subject to b) drying the hydrogel polymer.

Normal water content of the hydrogel polymer obtained in step a) is 30 to 60% by weight. On the other hand, the term "water content" as used throughout the specification means the value of the water content of the water-containing gel polymer subtracted from the weight of the polymer in the dry state with respect to the total weight of the water-containing gel polymer. Specifically, it is defined as a value calculated by measuring the weight loss according to moisture evaporation in the polymer during the process of raising the temperature of the polymer through infrared heating, wherein the drying conditions are raised to a temperature of 180 ℃ from room temperature The total drying time was set to 20 minutes, including 5 minutes of temperature rise in such a manner as to maintain at 180 ℃, to measure the moisture content.

Throughout this specification "drying temperature" may be defined as the temperature of the heating medium supplied for drying or the temperature of the drying reactor including the heating medium and the polymer in the drying process, the drying step is preferably a drying temperature of the drying step is 150 It may be from ℃ to 250 ℃, more preferably may proceed at a temperature of 160 ℃ to 200 ℃.

If the drying temperature is less than 150 ° C., the drying time may be too long, and the physical properties of the final superabsorbent polymer may be lowered. If the drying temperature exceeds 250 ° C., only the surface of the polymer is dried too much, and a subsequent grinding step is performed. Fine powder may occur, and there is a fear that the physical properties of the superabsorbent polymer to be finally formed decrease. On the other hand, the drying time is not limited to the configuration, but in consideration of the process efficiency, etc., it may proceed for 20 to 90 minutes.

In addition, if the drying method of the drying step is also commonly used as a drying step of the hydrogel polymer, it can be selected and used without limitation of the configuration. Specifically, the drying step may be performed by a method such as hot air supply, infrared irradiation, microwave irradiation, or ultraviolet irradiation. The water content of the polymer after the drying step may be 0.1 to 10% by weight.

On the other hand, the method for producing a super absorbent polymer according to the present invention may be further subjected to a simple grinding step before the drying step, if necessary, in order to increase the efficiency of the drying step. The simple grinding step before the drying step may be such that the particle size of the polymer of the hydrogel polymer is 1 mm to 15 mm. At this time, it is technically difficult to pulverize the polymer to a particle size of less than 1 mm due to the high water content of the hydrogel polymer, and also may be agglomerated phenomenon between the pulverized particles, when pulverizing to a particle size exceeding 15 mm, The effect of increasing the efficiency of the subsequent drying step is negligible.

In the simple grinding step before the drying step, the pulverizer used is not limited in configuration, but specifically, a vertical pulverizer, a turbo cutter, a turbo grinder, and a rotary machine are used. It consists of rotary cutter mill, cutter mill, disc mill, shred crusher, crusher, chopper and disc cutter It may include any one selected from the group of grinding devices, but is not limited to the above examples.

As such, when the grinding step is performed in order to increase the drying efficiency before the drying step, the polymer may be stuck to the surface of the grinder due to the high moisture content polymer. Therefore, in order to increase the efficiency of the pulverization step before drying of the hydrous gel polymer, additives that can prevent sticking during pulverization may be further used. The type of the additives that can be used specifically includes, but is not limited to, the fine powder aggregation inhibitor such as steam, water, surfactants, inorganic powders such as clay or silica; Thermal polymerization initiators such as persulfate initiators, azo initiators, hydrogen peroxide, and ascorbic acid, epoxy crosslinkers, diol crosslinkers, crosslinking agents including acrylates of difunctional or trifunctional or polyfunctional groups or more, and hydroxyl groups. It may be a crosslinking agent such as a compound of a monofunctional group to be included, but is not limited to the examples described above.

Thereafter, the manufacturing method of the super absorbent polymer according to the present invention is subjected to the drying step, and then c) grinding the dried polymer. The particle size of the polymer obtained after the grinding step is 150 to 850㎛. In the manufacturing method of the superabsorbent polymer according to the present invention, the pulverizer used to grind to such a particle size is specifically a pin mill, a hammer mill, a screw mill, a roll mill (roll mill), disk mill (disc mill) or jog mill (jog mill) and the like can be used, but is not limited thereto.

Thereafter, the method for preparing a super absorbent polymer according to the present invention is subjected to the step of d) adding particles having a property of the following i) to ii) and a surface crosslinking agent to the pulverized hydrogel polymer.

i) a BET specific surface area of 300 to 1500 m ² / g,

ii) porosity of at least 50%

In general, the surface of the superabsorbent polymer is hydrophilic, and is absorbed by capillary force, water bonding, inter-particaular diffusion, or van der Waals forces between particles when water is dried between particles when absorbed. Irreversible aggregation occurs. Therefore, water is also used essentially in the polymerization and surface crosslinking process of the superabsorbent polymer. Since the aggregation occurs, the internal load is increased, and consequently, it may be the cause of equipment failure. In addition, the superabsorbent polymer in the aggregated state as described above has a disadvantage in that a disintegration process for reducing the particle size to an appropriate particle size is introduced because the particle size is not suitable for the application. In addition, since a strong force is applied in the disintegration process, there is a problem that physical properties may be degraded due to crushing of the super absorbent polymer.

In order to solve the above problems, there have been attempts to introduce a variety of microparticles present on the surface of the superabsorbent polymer and may serve to hinder direct agglomeration between the resin particles. Is prevented, but has the disadvantage that the absorption characteristics of the super absorbent polymer is reduced.

In order to solve the above problems, the microparticles introduced into the superabsorbent polymer of the present invention have a particle size of 2 nm to 50 μm. In addition, the microparticles may have a BET specific surface area of 300 to 1500 m ² / g, preferably 500 to 1500 m ² / g, more preferably 700 to 1500 m ² / g. In addition, the fine particles may have a superhydrophobicity of 125 ° or more, preferably 140 ° or more, and more preferably 145 ° or more. In addition, the microparticles may have a porosity of 50% or more, preferably porosity of 90% or more. Since the manufacturing method of the super absorbent polymer of the present invention uses the fine particles having the above characteristics, not only the influence of water on the surface of the resin can be reduced, but also the porous super hydrophobic fine particles are used, so that aggregation is remarkable. It can be reduced, and even when using a relatively small amount of fine particles, the permeability can be easily improved, high content and easy maintenance thereof.

The fine particles added in the method of preparing the superabsorbent polymer according to the present invention are not limited as long as they are materials having the same properties as those of i) to ii), specifically, silica, alumina, titania (TiO ₂ ), and carbon ( Inorganic oxides such as carbon), inorganic compounds, organic polymers, ion exchange resins, metals, metal salts, and the like, but are not limited thereto.

In addition, the fine particles are preferably added in 0.001 to 1 parts by weight with respect to 100 parts by weight of the super absorbent polymer. If the amount of the fine particles is less than the above range, the hydrophobicity of the superabsorbent polymer is not sufficient. If the amount of the fine particles is more than the above range, the processability of the resin is poor.

In addition, it is a process of adding fine particles, used after dispersion in monomer solution, added to hydrogel after polymerization, and then dry mixed with resin particles dried first, and dispersed in water or organic solvent in which surface crosslinking solution is dissolved during surface crosslinking. After mixing and surface crosslinking, the surface crosslinking liquid may be separated from the dissolved water or the organic solvent and dry mixed, or dry mixing may be used for the final crosslinked product, but the present invention is not particularly limited thereto.

In addition, as long as the surface crosslinking agent added in the manufacturing method of the super absorbent polymer which concerns on this invention is a compound which can react with the functional group which a polymer has, there is no limitation in the structure. As said surface crosslinking agent, Preferably, in order to improve the characteristic of the superabsorbent polymer produced | generated, a polyhydric alcohol compound; Epoxy compounds; Polyamine compounds; Haloepoxy compound; Condensation products of haloepoxy compounds; Oxazoline compounds; Mono-, di- or polyoxazolidinone compounds; Cyclic urea compounds; Polyvalent metal salts; And it may be used one or more selected from the group consisting of alkylene carbonate compounds.

Specifically, examples of the polyhydric alcohol compound include mono-, di-, tri-, tetra- or polyethylene glycol, monopropylene glycol, 1,3-propanediol, dipropylene glycol, 2,3,4-trimethyl-1,3 -Pentanediol, polypropylene glycol, glycerol, polyglycerol, 2-butene-1,4-diol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, and One or more types selected from the group consisting of 1,2-cyclohexanedimethanol can be used.

Ethylene glycol diglycidyl ether and glycidol may be used as the epoxy compound, and polyamine compounds may be ethylenediamine, diethylenetriamine, triethylenetetraamine, tetraethylenepentamine, or pentaethylenehexamine. , At least one selected from the group consisting of polyethyleneimine and polyamide polyamine can be used.

As the haloepoxy compound, epichlorohydrin, epibromohydrin and α-methyl epichlorohydrin can be used. In addition, as a mono-, di-, or a polyoxazolidinone compound, 2-oxazolidinone etc. can be used, for example. And as an alkylene carbonate compound, ethylene carbonate etc. can be used. These may be used alone or in combination with each other. On the other hand, in order to raise the efficiency of a surface crosslinking process, it is preferable to use including at least 1 type of polyhydric alcohol compounds among these surface crosslinking agents, More preferably, C2-C10 polyhydric alcohol compounds can be used.

In addition, the amount of the surface crosslinking agent added to mix the surface crosslinking agent and to surface-treat the polymer particles may be appropriately selected depending on the kind of the surface crosslinking agent to be added or the reaction conditions. 0.001 to 5 parts by weight, preferably 0.01 to 3 parts by weight, and more preferably 0.05 to 2 parts by weight.

When the content of the surface crosslinking agent is too small, the surface crosslinking reaction hardly occurs, and when it exceeds 5 parts by weight with respect to 100 parts by weight of the polymer, the physical properties of the super absorbent polymer may be lowered due to the excessive surface crosslinking reaction.

At this time, the method of adding a surface crosslinking agent to a polymer does not have the limitation of the structure. The surface crosslinking agent and the polymer powder may be mixed in a reaction tank, a method of spraying the surface crosslinking agent on the polymer powder, a method of continuously supplying and mixing the polymer and the crosslinking agent into a reaction tank such as a mixer operated continuously, and the like.

Method for producing a super absorbent polymer according to the present invention goes through the step of e) surface crosslinking reaction.

And, according to another embodiment of the present invention, in order to proceed the temperature increase to the reaction temperature for the surface crosslinking reaction after the addition of the surface crosslinking agent within 1 to 60 minutes, preferably, when the surface crosslinking agent is added, the temperature of the polymer itself is It may be 20 ℃ to 80 ℃. In order to indicate the temperature of the polymer itself as described above, if the process is continuously carried out after the drying step proceeds to a relatively high temperature, and if it is difficult to shorten the process 7 hours, or shorten the process time, it is possible to heat the polymer separately. It may be.

In addition, the method for producing a superabsorbent polymer according to the present invention, after the addition of the surface crosslinking agent, in order to proceed the temperature rise to the reaction temperature for the surface crosslinking reaction within 1 to 60 minutes, the surface crosslinking agent itself added to the polymer is heated You may.

On the other hand, the method for producing a super absorbent polymer according to the present invention is to improve the efficiency of the surface cross-linking process, when the surface cross-linking reaction proceeds after the temperature rise to the reaction temperature for the surface cross-linking reaction within 1 to 60 minutes It is possible to minimize the residual monomer content of the final superabsorbent polymer obtained, and to obtain a superabsorbent polymer having excellent physical properties. At this time, the temperature of the surface crosslinking agent to be added can be adjusted to 5 ° C to 60 ° C, more preferably 10 ° C to 40 ° C. When the temperature of the surface crosslinking agent is less than 5 ° C., the effect of shortening the temperature increase rate to the surface crosslinking reaction according to the temperature of the surface crosslinking agent is insignificant, and when the temperature of the surface crosslinking agent exceeds 60 ° C., the surface crosslinking agent is not evenly dispersed in the polymer. You may not. Throughout this specification, the surface crosslinking reaction temperature may be defined as the total temperature of the polymer and the surface crosslinking agent added for the crosslinking reaction.

And there is no limitation in the structure as a temperature raising means for surface crosslinking reaction. Specifically, the heating medium may be supplied or directly heated by means such as electricity, but the present invention is not limited to the above-described example. Specifically, heat sources that may be used include steam, electricity, ultraviolet rays, infrared rays, and the like, and a heated thermal fluid may be used.

On the other hand, in the manufacturing method of the super absorbent polymer according to the present invention, after the temperature rise for the crosslinking reaction is made, the crosslinking reaction is 1 minute to 60 minutes, preferably 5 minutes to 40 minutes, most preferably 10 minutes to 20 minutes Can proceed. When the crosslinking reaction time is too short (less than 1 minute), a sufficient degree of crosslinking reaction may not occur, and when the crosslinking reaction time exceeds 60 minutes, the physical properties of the super absorbent polymer may deteriorate due to excessive surface crosslinking reaction, Polymer shredding may occur due to prolonged residence in the reactor.

Hereinafter, the present invention will be described in more detail with reference to Examples, but embodiments of the present invention disclosed below are exemplified to the last, and the scope of the present invention is not limited to these embodiments. The scope of the invention is indicated in the appended claims, and moreover contains all modifications within the meaning and range equivalent to the claims. In addition, "%" and "part" which show content in a following example and a comparative example are a mass reference | standard unless there is particular notice.

Example

Preparation Example: Preparation of Water-Soluble Gel Polymer

100 g of acrylic acid, 0.3 g polyethylene glycol diacrylate as crosslinking agent, 0.033 g diphenyl (2,4,6-trimethylbenzoyl) -phosphine oxide as initiator, 38.9 g caustic soda (NaOH), and 103.9 g water By mixing, a monomer mixture having a monomer concentration of 50% by weight was prepared.

Thereafter, the monomer mixture was placed on a continuously moving conveyor belt and irradiated with ultraviolet light (irradiation amount: 2 mW / cm 2) to undergo UV polymerization for 2 minutes to obtain a hydrous gel polymer.

EXAMPLES Preparation of Super Absorbent Polymers

Example 1

The hydrogel polymer prepared according to the preparation example was cut into 5 * 5 mm size and dried in a hot air dryer at 170 ° C. for 2 hours, pulverized with a pin mill grinder and then sieve (sieve) to a particle size of 150 to 850 μm. A super absorbent polymer was obtained. After mixing 0.15 g of porous superhydrophobic fine particle silica Aerogel (AeroZelTM, JIOS Co., Ltd.) at 1000 RPM for 60 seconds to 250 g of the superabsorbent polymer, a liquid mixture consisting of 0.75 g of ethylene carbonate and 6.75 g of water was administered as a surface crosslinking agent. Then mix for 60 seconds. Thereafter, the mixture was reacted at 190 ° C. for 60 minutes to obtain a finely pulverized superabsorbent polymer, and again, the particle size before pulverization of the pulverized superabsorbent polymer was measured, pulverized with a pin mill grinder, and then used as a sieve size. A superabsorbent polymer having a thickness of 150 to 850 µm was obtained. The particle size of the used Aerogel was 30 nm, had a BET specific surface area of 500 m ² / g, the contact angle to water was 150 °, and the porosity was 95%.

The particle size of the aerogel was analyzed according to ISO 13320 by using a Helium-Neon Laser Optical System (HELOS), by particle-free ultra-fast optical diffraction (Laser Diffraction). The BET specific surface area and porosity were measured using a BET analyzer. The contact angle of water was measured using a contact angle analyzer (KRUSS DSA100). Specifically, a double-sided tape was attached to a flat glass plate, and microparticles were applied as a monolayer thereon, followed by 5 μl of ultrapure water on a single layer. When raised, it is located in the form of a drop. At this time, the angle between the water droplet and the glass plate was measured four times, and then the average value was calculated.

Example 2

A super absorbent polymer was obtained in the same manner as in Example 1, except that 0.25 g of Silica Aerogel was used.

Example 3

A super absorbent polymer was obtained in the same manner as in Example 1, except that 11.75 g of water in the liquid mixture was used.

Example 4

A super absorbent polymer was obtained in the same manner as in Example 1, except that 0.25 g of Silica Aerogel and 11.75 g of water in the liquid mixture were used.

Comparative Example 1

Superabsorbent polymer was obtained in the same manner as in Example 1, except that REOLOSIL DM-30S was used as the fine particles. The particle size of REOLOSIL DM-30S used above was 7 nm, had a BET specific surface area of 230 m ² / g, the contact angle to water was 135 °, the porosity was 20% or less, and the measurement method was the same as in Example 1 .

Comparative Example 2

Superabsorbent polymer was obtained in the same manner as in Comparative Example 1 except that 0.25 g of REOLOSIL DM-30S was used as the fine particles.

Comparative Example 3

REOLOSIL DM-30S was used as the fine particles, except that 11.75 g of water in the liquid mixture was used in the same manner as in Comparative Example 1 to obtain a super absorbent polymer.

[Comparative Example 4]

Superabsorbent polymer was obtained by the same method as Comparative Example 1, except that 0.25 g of REOLOSIL DM-30S and 11.75 g of water in the liquid mixture were used as fine particles.

[Comparative Example 5]

Superabsorbent polymer was obtained in the same manner as in Example 1 except that no fine particles were used.

Comparative Example 6

A super absorbent polymer was obtained in the same manner as in Comparative Example 5, except that 11.75 g of the water in the liquid mixture was used.

The configurations of Examples 1 to 4 and Comparative Examples 1 to 6 are shown in Table 1 below.

Table 1

	Particle type	Particle Usage (g)	Liquid mixture
			Ethylene carbonate (g)	Water (g)
Example 1	Aerogel	0.15	0.75	6.75
Example 2		0.25		6.75
Example 3		0.15		11.75
Example 4		0.25		11.75
Comparative Example 1	REOLOSILDM-30S	0.15		6.75
Comparative Example 2		0.25		6.75
Comparative Example 3		0.15		11.75
Comparative Example 4		0.25		11.75
Comparative Example 5	-	-		6.75
Comparative Example 6				11.75

Experimental Example: Evaluation of Properties

In order to evaluate the physical properties of the superabsorbent polymers according to Comparative Examples 1 to 6 and Examples 1 to 4, the following test was conducted.

Experimental Example 1: Centrifugal Retention Capacity (CRC)

The water holding capacity of each of the superabsorbent polymers prepared in Comparative Examples 1 to 6 and Examples 1 to 4 was measured. The measurement of water retention capacity was based on the EDANA method WSP 241.3. In the prepared superabsorbent polymer, a particle size of 150 to 850 μm or 0.2 g of a sample with water was placed in a tea bag and precipitated in a 0.9% saline solution for 30 minutes. After dehydration for 3 minutes at 250G (gravity) centrifugal force was measured the amount of saline solution absorbed.

Experimental Example 2: Absorption Under Pressure (AUP)

The pressure-absorbing capacity of each of the superabsorbent polymers prepared in Comparative Examples 1 to 6 and Examples 1 to 4 was measured. The measurement of the pressure absorption capacity was based on the EDANA method WSP 242.3. In the prepared superabsorbent polymer, a particle size of 150 to 850 μm or 0.9 g of a sample with a fresh water was placed in a cylinder defined by EDATA, and the amount of the absorbed 0.9% saline solution for 60 minutes was measured after applying pressure with a piston and a weight of 0.7 psi.

Experimental Example 3: Finely ground superabsorbent polymer particle size

Particle sizes of the finely divided superabsorbent polymers of Comparative Examples 1 to 6 and Examples 1 to 4 were measured. The measurement of the superabsorbent polymer particle size was based on the EDANA method WSP 220.3. 100 g of superabsorbent polymer was divided into 850 μm, 600 μm, 300 μm, 150 μm, and a mesh of Pan, and then vibrated for 10 minutes at 1.44 mm amplitude and a frequency of 50 Hz. .

Table 2 shows the results of measuring particle sizes of the water-retaining capacity, the pressure-absorbing capacity, and the finely divided superabsorbent polymer of Experimental Examples 1 to 3 as described above.

TABLE 2

	Water retention capacity (g / g)	Pressure Absorption Capacity (g / g)	Particle size classification (%)
			150㎛ or less	150 ~ 300㎛	300 ~ 600㎛	600 ~ 850㎛	More than 850㎛
Example 1	33.9	20.3	0.0	2.3	28.3	43.9	25.5
Example 2	33.1	19.5	0.7	11.3	52.5	31.4	4.1
Example 3	33.3	22.1	0.0	0.6	11.2	20.2	68.0
Example 4	31.1	20.0	0.0	1.0	29.3	38.7	31.0
Comparative Example 1	33.7	21.3	0.2	2.3	19.8	29.0	48.7
Comparative Example 2	34.5	19.6	0.5	8.4	46.2	36.2	8.7
Comparative Example 3	32.2	22.7	0.0	0.4	5.2	7.3	87.1
Comparative Example 4	32.3	21.5	0.0	0.5	5.6	8.5	85.4
Comparative Example 5	34.1	23.8	0.0	1.7	15.5	27.7	55.1
Comparative Example 6	32.7	24.0	0.0	0.9	6.0	10.9	82.2

Based on the results of Table 2, the superabsorbent polymer in which the superhydrophobic microparticles are introduced to the surface, the aggregation decreases as the hydrophobicity of the surface increases, and as a result, the workability increases.

In general, in the surface crosslinking process of the superabsorbent polymer, the surface crosslinking agent is dissolved in water and then mixed with the superabsorbent polymer to induce even distribution and penetration into the resin surface. In this case, the water used is agglomerated by increasing the viscosity of the superabsorbent polymer surface. This causes, and also, a strong force is required for the pulverization of the aggregated superabsorbent polymer, which causes disadvantages such as damage to the superabsorbent polymer.

The superabsorbent polymer, in which the superhydrophobic particles of Example 1 were introduced and modified to be hydrophobic, is distributed in a smaller particle size than the superabsorbent polymer prepared in Comparative Example 5, and has a particle size of 850 µm or less even though there is no grinding step. By maintaining about% it can be seen that the processability increases.

In addition, Example 1 and Comparative Example 1 show a change in processability based on the hydrophobic difference of the superhydrophobic microparticles introduced. When the same amount of the superhydrophobic microparticles is used, the particle size decreases due to the decrease in the aggregation, and the particle size of the super absorbent polymers obtained from Examples 1 to 4 in which the highly hydrophobic microparticles are introduced is compared. Compared with the particle size of the super absorbent polymer obtained from 4, it is distributed in the smaller one, and it turns out that there is little difference in a water holding capacity and a pressure absorbing capacity.

Claims (21)

1. a) preparing a hydrogel polymer by thermally polymerizing or photopolymerizing a monomer composition comprising a water-soluble ethylenically unsaturated monomer and a polymerization initiator;

   b) drying the hydrogel polymer;

   c) grinding the dried hydrogel polymer;

   d) adding particles and a surface crosslinking agent having the properties of i) to ii) to the pulverized hydrogel polymer; And

   e) a method for producing a super absorbent polymer comprising the step of performing a surface crosslinking reaction.

   i) a BET specific surface area of 300 to 1500 m ² / g,

   ii) porosity of at least 50%
2. The method according to claim 1,

   The particles have a particle size of 2 nm ~ 50 ㎛ characterized in that the manufacturing method of the super absorbent polymer.
3. The method according to claim 1,

   The particle has a contact angle with respect to water has a super hydrophobicity of 125 ° or more, characterized in that for producing a super absorbent polymer.
4. The method according to claim 1,

   The particles are a method of producing a super absorbent polymer, characterized in that the particle size of 2 nm ~ 50 ㎛ and the contact angle to water has a super hydrophobicity of 125 ° or more.
5. The method according to claim 1,

   The fine particles have a BET specific surface area (500 to 1500 m ² / g) method of producing a super absorbent polymer, characterized in that.
6. The method according to claim 1,

   The fine particles have a BET specific surface area (700-1500 m ² / g) method of producing a super absorbent polymer, characterized in that.
7. The method according to claim 3 or 4,

   The fine particles are a method of producing a super absorbent polymer, characterized in that the contact angle to the water has a super hydrophobicity of 140 ° or more.
8. The method according to claim 3 or 4,

   The fine particles are a method of producing a super absorbent polymer, characterized in that the contact angle to water has a superhydrophobicity of 145 ° or more.
9. The method according to claim 1,

   The fine particles are a method of producing a super absorbent polymer, characterized in that having a porosity (porosity) of 90% or more.
10. The method according to claim 1,

    The fine particles are contained in an amount of 0.001 to 1 part by weight based on 100 parts by weight of the super absorbent polymer.
11. The method according to claim 1,

    The fine particle is a method for producing a super absorbent polymer, characterized in that at least one member selected from the group consisting of silica, alumina, carbon (Carbon) and titania (TiO ₂ ).
12. The method according to claim 1,

    Before the drying step of step b), the method of producing a super absorbent polymer, characterized in that it further comprises the step of grinding the hydrogel polymer to a particle size of 1mm to 15mm.
13. The method according to claim 1,

    The drying step of step b) is a method for producing a super absorbent polymer, characterized in that at a temperature of 150 ℃ to 250 ℃.
14. The method according to claim 1,

    The grinding step of step c), the method for producing a super absorbent polymer, characterized in that the hydrogel polymer is pulverized to a particle size of 150 to 850㎛.
15. The method according to claim 1,

    The surface crosslinking agent of step d) is a polyhydric alcohol compound; Epoxy compounds; Polyamine compounds; Haloepoxy compound; Condensation products of haloepoxy compounds; Oxazoline compounds; Mono-, di- or polyoxazolidinone compounds; Cyclic urea compounds; Polyvalent metal salts; And an alkylene carbonate compound. The method for producing superabsorbent polymer, characterized in that at least one selected from the group consisting of.
16. The method according to claim 1,

    Method for producing a super absorbent polymer, characterized in that the surface cross-linking agent of step d) is added to 0.001 to 5 parts by weight based on 100 parts by weight of the pulverized polymer.
17. The method according to claim 1,

    In the step d), the surface temperature of the polymer in the step of adding the surface cross-linking agent is a method for producing a super absorbent polymer, characterized in that 60 to 90 ℃.
18. The method according to claim 1,

    In the step d), the temperature of the surface cross-linking agent to be added is a method of producing a super absorbent polymer, characterized in that 5 to 40 ℃.
19. The method according to claim 1,

    In the step e), the surface crosslinking reaction is a method for producing a super absorbent polymer, characterized in that for 10 minutes to 120 minutes.
20. The method according to claim 1,

    In the step e), the method of manufacturing a super absorbent polymer, characterized in that the temperature is raised by irradiating any one or more selected from a heat source group consisting of steam, electricity, ultraviolet rays and infrared rays.
21. The method according to claim 1,

    After the surface crosslinking reaction step of step e), the method of producing a super absorbent polymer, characterized in that further comprising the step of pulverizing the superabsorbent resin again to a particle size of 150 to 850 ㎛.