KR102186939B1 - Method for preparing super absorbent polymer - Google Patents

Abstract

A method for producing a superabsorbent polymer having an improved absorption rate, comprising preparing a second composition by contacting a first composition containing a hydrophilic monomer, a crosslinking agent, and a polymerization initiator with a foamable material, and preparing a second composition in a belt-type reactor There is provided a method for producing a super absorbent polymer comprising the step of polymerizing in a phase.

Description

Manufacturing method of super absorbent polymer {METHOD FOR PREPARING SUPER ABSORBENT POLYMER}

The present invention relates to a method for producing a super absorbent polymer.

Super Absorbent Polymer (SAP) is a synthetic polymer material that has a function of absorbing moisture 500 to 1,000 times its own weight, and each developer has a SAM (Super Absorbency Material), AGM (Absorbent Gel Material). ) And so on. Since the above superabsorbent resin has begun to be put into practical use as a sanitary tool, nowadays, in addition to hygiene products such as paper diapers for children, soil repair agents for horticulture, water resistant materials for civil engineering and construction, sheets for seedlings, freshness maintenance agents in the food distribution field, and poultice. It is widely used as a material for supplies.

As a method of preparing the super absorbent polymer as described above, a method by reverse phase suspension polymerization or a method by aqueous solution polymerization is known. Regarding reverse-phase suspension polymerization, for example, Japanese Patent Publication No. 56-161408, Japanese Patent Publication No. 57-158209, and Japanese Patent Publication No. 57-198714 are disclosed. As a method of aqueous solution polymerization, a thermal polymerization method in which heat is applied to the aqueous solution to polymerize, and a photopolymerization method in which polymerization is performed by irradiation with ultraviolet rays or the like are known.

On the other hand, as the uses of super absorbent polymers are diversified, absorption ratio, centrifuge retention capacity (CRC), absorption under pressure (AUP), absorption rate (Free Swelling Rate, FSR), liquid permeability, and antibacterial properties , And various properties such as rechargeability are required. In particular, if the absorption rate is insufficient, the surface of a diaper or the like becomes sticky, reducing the feeling of use, and may cause skin diseases and odors.

Accordingly, the problem to be solved by the present invention is to provide a method of manufacturing a super absorbent polymer having an improved absorption rate.

At the same time, it is to provide a method for producing a super absorbent polymer having sufficient water holding capacity and water absorption under pressure.

The problems of the present invention are not limited to the technical problems mentioned above, and other technical problems that are not mentioned will be clearly understood by those skilled in the art from the following description.

A method of manufacturing a superabsorbent polymer according to an embodiment for solving the above problem may include preparing a second composition by contacting a first composition including a hydrophilic monomer, a crosslinking agent, and a polymerization initiator with a foamable material; And polymerizing the second composition on a belt-type reactor.

In the method for producing a super absorbent polymer according to an embodiment for solving the above problem, in the step of preparing a second composition by contacting the first composition and a foamable material, a foaming agent powder is added to the belt surface of the belt-type reactor. Providing and providing the first composition on the belt surface provided with the foaming agent powder.

In the method of manufacturing a super absorbent polymer according to an embodiment for solving the above problem, the step of preparing a second composition by contacting the first composition and a foamable material comprises: providing the first composition to a mixing tank And providing an aqueous foaming agent solution to the mixing tank.

In the method for producing a super absorbent polymer according to an embodiment for solving the above problem, between the step of preparing the second composition and the step of polymerizing the second composition, the second It may further comprise the step of providing the composition.

In the method of manufacturing a superabsorbent polymer according to an embodiment for solving the above problem, the mixing tank is a stirrer, and the step of preparing the second composition comprises adding the first composition and the foaming agent aqueous solution in the stirrer. It may further include a step of stirring at more than rpm.

In the method of manufacturing a super absorbent polymer according to an embodiment for solving the above problem, the mixing tank may be an in-line homogenizer.

In the method of manufacturing a super absorbent polymer according to an embodiment for solving the above problem, the content of the foaming agent in the aqueous foaming agent solution may be 1% by weight to 10% by weight.

In the method for producing a super absorbent polymer according to an embodiment for solving the above problem, the second composition is a mixture containing bubbles, and the step of polymerizing the second composition on a belt-type reactor includes the bubbles It may be a step of polymerizing the mixture to form a polymer having a pore structure.

In the method for producing a super absorbent polymer according to an embodiment for solving the problem, after the step of forming the polymer having the pore structure, drying the polymer, and further comprising the step of pulverizing the polymer I can.

In the method of manufacturing a super absorbent polymer according to an embodiment for solving the above problem, the foamable material may include sodium hydrogen carbonate (NaHCO ₃ ) and/or sodium carbonate (NaCO ₃ ).

Details of other embodiments are included in the detailed description and drawings.

According to the method for producing a super absorbent polymer according to an embodiment of the present invention, by continuously performing a process of forming bubbles in a monomer composition, a process of polymerizing the monomer composition, and a post-treatment process using a belt-type continuous reactor. Fairness can be improved.

In addition, since the foamable material forms bubbles in the monomer composition, it is possible to impart a pore structure to the polymer, and thus a super absorbent polymer having an improved absorption rate can be prepared.

In addition, by providing the foamable material to the belt surface of the belt-type reactor and then providing the monomer composition, or by strongly stirring the foamable material and the monomer composition and then providing the mixture to the belt surface of the belt-type reactor, the absorption rate can be further improved. I can.

Effects according to the embodiments of the present invention are not limited by the contents illustrated above, and more various effects are included in the present specification.

1 is a flow chart showing a method of manufacturing a super absorbent polymer according to an embodiment of the present invention.
FIG. 2 is a block diagram schematically illustrating a method of manufacturing the super absorbent polymer of FIG. 1.
3 is a flow chart showing a method of manufacturing a super absorbent polymer according to another embodiment of the present invention.
4 is a configuration diagram schematically showing a method of manufacturing the super absorbent polymer of FIG. 3.

Advantages and features of the present invention, and a method of achieving them will become apparent with reference to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms different from each other, and only the embodiments make the disclosure of the present invention complete, and those skilled in the art to which the present invention pertains. It is provided to fully inform the person of the scope of the invention, and the invention is only defined by the scope of the claims.

In the present specification, "C _AB " is defined as having A or more and B or less, and for example, "C _1-5 alkyl group" is an alkyl group having 1 to 5 carbon atoms. "And/or" includes each and every combination of one or more of the recited items. The same reference numerals refer to the same components throughout the specification.

Although the first, second, and the like are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are only used to distinguish one component from another component.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a flow chart showing a method of manufacturing a super absorbent polymer according to an embodiment of the present invention. FIG. 2 is a block diagram schematically illustrating a method of manufacturing the super absorbent polymer of FIG. 1.

1 and 2, the method of manufacturing a super absorbent polymer according to an embodiment of the present invention includes preparing a monomer composition (S110), preparing a foamable material (S120), and the monomer composition in a reactor. And preparing a bubble-formed monomer composition by contacting the foamable material (S130), polymerizing the bubble-formed monomer composition (S140), and drying and pulverizing the polymer (S150).

First, a monomer composition is prepared (S110). The monomer composition 101 may include a hydrophilic monomer, a crosslinking agent, and a polymerization initiator.

The hydrophilic monomer may be a monomer including a hydrophilic group, such as a hydroxyl group (-OH), a carboxyl group (-COOH), an amide group (-NH ₂ ), and the like. The hydrophilic monomer is not limited as long as it is generally used in the manufacture of a super absorbent polymer, but may be, for example, a water-soluble ethylenically unsaturated monomer. The water-soluble ethylenically unsaturated monomer may be any one of an anionic monomer and a salt thereof, a nonionic hydrophilic-containing monomer, and an amino group-containing unsaturated monomer, a quaternary product thereof, or a mixture thereof.

Specifically, examples of the anionic monomer and its salts include acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, 2-acryloylethane sulfonic acid, 2-methacryloylethanesulfonic acid, 2-( And meth)acryloylpropanesulfonic acid and 2-(meth)acrylamide-2-methylpropanesulfonic acid.

In addition, examples of the nonionic hydrophilic-containing monomer include (meth)acrylamide, N-substituted (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, Methoxy polyethylene glycol (meth) acrylate and polyethylene glycol (meth) acrylate.

Further, examples of the amino group-containing unsaturated monomer and its quaternary product include (N,N)-dimethylaminoethyl (meth)acrylate and (N,N)-dimethylaminopropyl (meth)acrylamide. .

The concentration of the water-soluble ethylenically unsaturated monomer in the monomer composition 101 may be appropriately selected in consideration of polymerization time and polymerization conditions (feed rate, polymerization time, etc.), but, for example, in the range of 30% by weight or more and 60% by weight or less. Can be

The crosslinking agent includes an atomic group capable of reacting with a functional group of the hydrophilic monomer and at least one ethylenically unsaturated group, or an atomic group capable of reacting with a functional group of the hydrophilic monomer and a functional group formed by hydrolysis of the hydrophilic monomer. A compound containing more than two can be used. The crosslinking agent may be included in a range of about 0.01 parts by weight to about 0.5 parts by weight based on 100 parts by weight of the hydrophilic monomer.

The crosslinking agent is C _8-12 bisacrylamide, C _8-12 bismethacrylamide, C _2-12 polyol poly(meth)acrylate, C _2-10 polyol poly(meth)allyl ether, or a mixture thereof It can be any one of.

Specifically, examples of the crosslinking agent include (poly) ethylene glycol (meth) acrylate, (poly) propylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, ethoxyl (3)-trimethylol Propanetri(meth)acrylate, ethoxyl(6)-trimethylolpropanetri(meth)acrylate, ethoxyl(9)-trimethylolpropanetri(meth)acrylate, ethoxyl(15)-trimethylolpropanetri (Meth)acrylate glycerin tri(meth)acrylate, glycerin acrylate methacrylate, 2,2-bis[(acryloxy)methyl]butyl acrylate (3EO), N,N'-methylenebis(meth)acrylic Rate, ethyleneoxy (meth)acrylate, polyethyleneoxy (meth)acrylate, propyleneoxy (meth)acrylate, glycerin, glycerin diacrylate, glycerin triacrylate, trimethylol triacrylate, triallylamine, tri Aryl cyanurate, triallyl isocyanate, pentaethyleneimine, ethylene glycol, polyethylene glycol diethylene glycol, polyethylene glycol diacrylate, polymethylolpropane triacrylate, propylene glycol, etc., but are not limited thereto. .

The polymerization initiator may include at least one of a photo polymerization initiator, a thermal polymerization initiator, and an oxidation-reduction initiator. For example, the monomer composition 101 may include a photopolymerization initiator and a thermal polymerization initiator as a polymerization initiator.

The photopolymerization initiator induces the polymerization reaction of the monomer composition 101 to be initiated when irradiated with ultraviolet rays, and the thermal polymerization initiator induces the polymerization reaction of the monomer composition 101 to be initiated by heating, and the oxidation -The reduction initiator may induce the initiation of the polymerization reaction of the monomer composition 101 by an oxidation-reduction reaction.

The photopolymerization initiator is diethoxy acetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 4-(2-hydroxy ethoxy)phenyl-(2-hydroxy)-2-propyl Acetophenone derivatives such as ketone and 1-hydroxycyclohexylphenyl ketone; Benzoin alkyl ether compounds such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; benzophenone derivatives such as o-benzoyl methyl benzoate, 4-phenyl benzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, and (4-benzoyl benzyl) trimethyl ammonium chloride; Thioxanthone-based compounds; Bis(2,4,6-trimethylbenzoyl)-phenyl phosphine oxide, diphenyl(2,4,6-trimethylbenzoyl)-phosphine oxide, diphenyl (2,4,5-trimethylbenzoyl)-phosphine oxide Acyl phosphine oxide derivatives such as seeds; Or 2-hydroxy methyl propionitrile, 2,2'-(azobis(2-methyl-N-(1,1'-bis(hydroxymethyl)-2-hydroxyethyl)propion amide) Compounds; azo initiators; peroxide initiators; redox initiators; organic halide initiators; sodium persulfate (Na2S2O8); potassium persulfate (K2S2O8); or a mixture thereof The thermal polymerization initiator may be used by mixing one or two or more of an azo-based initiator, a peroxide-based initiator, a redox-based initiator, or an organic halide initiator. .

The content of the polymerization initiator in the monomer composition 101 may be appropriately selected so as to exhibit a polymerization initiation effect. For example, the photopolymerization initiator is in the range of about 0.005 to 0.1 parts by weight based on 100 parts by weight of the hydrophilic monomer. And, in the case of the thermal polymerization initiator, it may be included in the range of about 0.01 to 0.5 parts by weight based on 100 parts by weight of the hydrophilic monomer.

Then, a foamable material is prepared (S120). The foamable material may be a foaming agent powder 201. The blowing agent powder 201 is not particularly limited as long as it is a material that can react with an acid to form bubbles, but, for example, sodium hydrogen carbonate (NaHCO ₃ ), sodium carbonate (NaCO ₃ ), potassium hydrogen carbonate (KHCO ₃ ) , Ammonium carbonate ((NH ₄ ) ₂ CO ₃ H ₂ O), ammonium hydrogen carbonate (NH ₄ HCO ₃ ), magnesium carbonate (MgCO ₃ ), calcium carbonate (CaCO ₃ ), barium carbonate (BaCO ₃ ), and/or These may include hydrates. In addition, the foaming agent powder 201 may have a particle size of about 1 μm to 150 μm. By increasing the contact area between the blowing agent powder 201 and the monomer composition 101 within the above range, bubbles capable of imparting a pore structure having a sufficient amount and size to the polymer to be described later can be formed.

Then, the monomer composition and the foaming agent powder are brought into contact with each other in the reactor to prepare a monomer composition in which bubbles are formed (S130). In an exemplary embodiment, the reactor may be a continuous reactor, such as a belt reactor. The belt-type reactor is arranged to form a closed curve between the two transfer rolls (4,4') and the two transfer rolls (4,4') and proceeds in a certain direction by rotation of the transfer rolls (4,4'). It may include a belt (5). Specifically, two or more conveying rolls 4 and 4'may be provided depending on the length or arrangement of the belt 5, and a power source such as a motor is connected so that one surface of the belt 5 forms a horizontal surface and is in a certain direction. To proceed. The reactant is loaded and transported on one side of the belt 5, and the reaction can proceed continuously. In some embodiments, the plurality of conveying rolls may be disposed at different heights with respect to the horizontal plane so that one surface of the belt may form an inclination.

In this case, the step (S130) of preparing a bubble-formed monomer composition 301 by contacting the monomer composition and the blowing agent powder on a belt-type reactor (S130) is a step (S131) of providing the blowing agent powder 201 to the belt-type reactor, and Providing the monomer composition 101 to the belt-type reactor may include the step of contacting the blowing agent powder 201 and the monomer composition 101 (S132).

The step of providing the blowing agent powder 201 to the belt-type reactor (S131) may be a step of applying the blowing agent powder 201 to the belt 5 surface of the belt-type reactor. The foaming agent powder 201 may be loaded and transported on one side of the belt 5. In addition, the step of contacting the foaming agent powder 201 and the monomer composition 101 (S132) may be a step of supplying the monomer composition 101 to the surface of the belt 5 to which the foaming agent powder 201 is applied. The monomer composition supply unit 1 may be located behind the blowing agent powder supply unit 2 with respect to the traveling direction of the belt 5. By supplying the monomer composition 101 onto the foaming agent powder 201 already applied to the belt 5 surface, the foaming agent powder 201 and the monomer composition 101 are uniformly contacted and mixed, and the foaming agent powder 201 is a monomer By reacting with the acid in the composition 101, air bubbles 301a may be formed. The bubble-formed monomer composition 301 may be loaded and transported on one side of the belt 5.

Subsequently, the bubble-formed monomer composition 301 is polymerized on a belt-type reactor (S140). Specifically, the bubble-formed monomer composition 301 is conveyed by the belt 5, a continuous polymerization reaction is performed, and a sheet-like polymer 401 having a pore structure 401a may be formed.

In an exemplary embodiment, the step of polymerizing the monomer composition 301 in which bubbles are formed (S140) may be a step of performing a photopolymerization reaction by irradiating light. The light irradiation unit 6 is a light source such as an Xe lamp, a mercury lamp, and a metal halide lamp, and the light irradiation unit 6 may be positioned behind the monomer composition supply unit 1 with respect to the traveling direction of the belt 5. The light may be ultraviolet rays having a wavelength in the range of about 200 nm to 400 nm. In addition, it may be irradiated with an exposure amount of about 0.5 mw/cm ² to 500 mw/cm ² . In addition, the exposure time, that is, the time during which the monomer composition 301 on one side of the belt 5 is irradiated with light by the light irradiation unit 6 may range from about 10 seconds to 5 minutes, or about 20 seconds to 3 minutes. Effective photopolymerization reaction may occur within the above wavelength, exposure amount, and exposure time range, and crosslinking points of the polymer due to excessive light irradiation may be prevented from being cut.

In another embodiment, the step of polymerizing the bubble-formed monomer composition may be a step of performing a thermal polymerization reaction by applying heat. For example, when the monomer composition includes a thermal polymerization initiator, heat may be applied or a thermal polymerization reaction may proceed due to heat generated during a photopolymerization reaction. In this case, the heat supply unit may be located behind the monomer composition supply unit with respect to the traveling direction of the belt.

Then, the polymer is dried and pulverized (S150). In the step of drying and pulverizing the polymer (S150), the sheet-like polymer 401 on the surface of the belt 5 may be dried and pulverized while passing through a dryer (not shown) and a pulverizer (not shown).

Drying the polymer may be a step of drying the residual solvent of the polymer. Drying of the polymer 401 may be performed using a hot air dryer, fluidized bed dryer, air flow dryer, infrared dryer, or dielectric heating dryer, and about 100 to 200 for preventing deterioration of the polymer 401 and for efficient drying. It may be carried out at a temperature of about 20 minutes to 80 minutes, or about 40 minutes to 60 minutes. The step of pulverizing the polymer is a step of pulverizing or pulverizing the obtained sheet-like polymer 401 to a predetermined size by transferring the obtained sheet-like polymer 401 after the polymerization reaction is completed. For example, the sheet-like polymer 401 has a particle diameter of about 1 cm. It may be pulverized or crushed into a particulate polymer having a size of 3 cm. The step of pulverizing the polymer may be performed using a cutter type cutter, a chopper type cutter, a kneader type cutter, a vibration type grinder, an impact type grinder, a friction type grinder, or the like.

Meanwhile, in some embodiments, the drying of the polymer and the pulverization of the polymer may be alternately performed a plurality of times, or some may be omitted.

Hereinafter, a method of manufacturing a super absorbent polymer according to another embodiment of the present invention will be described. However, in order not to obscure the essence of the present invention, a description of a configuration that is substantially the same as or similar to the method of manufacturing the super absorbent polymer according to the above-described embodiment will be omitted, which is clearly to those skilled in the art from the accompanying drawings. It will be understandable.

3 is a flow chart showing a method of manufacturing a super absorbent polymer according to another embodiment of the present invention. 4 is a configuration diagram schematically showing a method of manufacturing the super absorbent polymer of FIG. 3.

3 and 4, a method of manufacturing a super absorbent polymer according to another embodiment of the present invention includes preparing a monomer composition (S210), preparing a foamable material (S220), the monomer composition and the foamable material Providing a mixture of the mixture to the reactor (S230), polymerizing the mixture of the monomer composition and the foamable material (S240), and drying and pulverizing the polymer (S250).

First, a monomer composition is prepared (S210). The monomer composition 101 may include a hydrophilic monomer, a crosslinking agent, and a polymerization initiator. The monomer composition 101 may be a composition that is substantially the same as the monomer composition of the embodiment according to FIG. 1, and a detailed description thereof will be omitted.

Then, a foamable material is prepared (S220). The foamable material may be an aqueous foaming agent solution 202. The foaming agent aqueous solution 202 may be prepared by dissolving a foaming agent in a solvent such as water. The blowing agent is not particularly limited as long as it is a material capable of forming bubbles by reacting with an acid, but for example, sodium hydrogen carbonate (NaHCO ₃ ), sodium carbonate (NaCO ₃ ), potassium hydrogen carbonate (KHCO ₃ ), ammonium carbonate ((NH ₄ ) ₂ CO ₃ H ₂ O), ammonium hydrogen carbonate (NH ₄ HCO ₃ ), magnesium carbonate (MgCO ₃ ), calcium carbonate (CaCO ₃ ), barium carbonate (BaCO ₃ ), and/or hydrates thereof It may include. In addition, the content of the blowing agent in the aqueous blowing agent solution 202 may be about 1% to 10% by weight. When the content of the blowing agent is 10% by weight or more, bubbles capable of imparting a pore structure having a sufficient amount and size to the polymer may be formed, and when the content is 10% by weight or less, the shape of the sheet-like polymer may be maintained.

Subsequently, a mixture of the monomer composition and an aqueous blowing agent solution is provided to the reactor (S230). The reactor may be a continuous reactor, such as a belt-type reactor.

In this case, the step of providing a mixture 302 of a monomer composition and an aqueous blowing agent solution to a belt-type reactor (S230) is a step of providing the monomer composition 101 to a mixing tank (S231), and an aqueous blowing agent solution 202 in the mixing tank Providing the step (S232), the step of contacting the monomer composition 101 and the blowing agent aqueous solution 202 (S233), and providing a mixture 302 of the monomer composition 101 and the blowing agent aqueous solution 202 to a belt-type reactor It may include a step (S234).

In the step of providing the monomer composition 101 to the mixing tank (S231) and the providing of the blowing agent aqueous solution 202 to the mixing tank (S232), the mixing tank may be a stirrer (3). In this case, the step of providing the monomer composition 101 to the stirrer 3 (S231) is performed prior to the step (S232) of providing the foaming agent aqueous solution 202 to the stirrer 3, or performed at the same time. I can. In some embodiments, the mixing tank may use an in-line homogenizer.

The step of contacting the monomer composition 101 and the aqueous foaming agent 202 (S233) may be a step of preparing a mixture 302 by mixing and stirring the monomer composition 101 and the aqueous foaming agent 202. The stirring speed of the stirrer 3 may be about 250 rpm or more, but is not limited thereto. Within the above range, a pore structure having a sufficient amount and size can be provided to the polymer to be described later. The foaming agent component of the foaming agent aqueous solution 202 may react with an acid in the monomer composition 101 in the presence of stirring to form a large amount of air bubbles (not shown) in the mixture 302.

Next, the step (S234) of providing a mixture 302' of the monomer composition 101 and the aqueous blowing agent solution 202 to the belt-type reactor (S234) is a monomer composition 101 and an aqueous blowing agent solution on the surface of the belt 5 of the belt-type reactor. It may be a step of supplying a mixture of (202). The mixture 302' of the monomer composition 101 and the aqueous foaming agent 202 may be loaded on one side of the belt 5 and transferred, and the mixture 302' of the monomer composition 101 and the aqueous foaming agent 202 may be bubbled. (302'a) may be contained.

Subsequently, the bubble-formed monomer composition 302' is polymerized on a belt-type reactor (S240). Specifically, the bubble-formed mixture 302' is conveyed by the belt 5, and a continuous polymerization reaction is performed, and a sheet-like polymer 402 having a pore structure 402a may be formed. In an exemplary embodiment, the step of polymerizing the bubble-formed mixture 302' (S240) may be a step of performing a photopolymerization reaction by irradiating light or performing a thermal polymerization reaction by applying heat, and the light irradiation unit ( 6) Alternatively, the heat supply may be located behind the mixture supply 3 ′ with respect to the traveling direction of the belt 5.

Then, the polymer is dried and pulverized (S250). Steps of drying and pulverizing the polymer have been described above together with the embodiment according to FIG. 1, so a detailed description thereof will be omitted.

Hereinafter, a method of manufacturing a super absorbent polymer according to the present invention will be described in more detail with reference to Preparation Examples, Comparative Examples and Experimental Examples.

< Manufacturing example 1>

After adding 7.2 kg of 20% sodium hydroxide aqueous solution to 3.7 kg of acrylic acid, 11 g of ethoxyl-trimethylolpropane triacrylate as an internal crosslinking agent, and diphenyl (2,4,5-trimethylbenzoyl)-phos as a photoinitiator 1.2 g of pin oxide was added to prepare a water-soluble unsaturated monomer composition (neutralization degree of acrylic acid-based monomer: 70 mol%). Then, sodium hydrogen carbonate powder having an average particle diameter of 100 μm was prepared. Subsequently, sodium hydrogen carbonate was first applied to the belt surface of a belt-type continuous reactor having a width of 30 cm and a feed rate of 33 cm/min, and after 10 seconds, a water-soluble unsaturated monomer composition was supplied onto the belt coated with sodium hydrogen carbonate, After 20 seconds, photopolymerization was performed to prepare a sheet-like polymer. At this time, the content ratio of the sodium hydrogen carbonate powder and the water-soluble unsaturated monomer composition is 1 part by weight of sodium hydrogen carbonate powder based on 100 parts by weight of the water-soluble unsaturated monomer composition. Next, the prepared sheet-like polymer was pulverized into particles through a meat chopper on a belt, and then dried in a hot air dryer at 170° C. for 40 minutes. The dried particulate polymer was pulverized once again using a cutting mill grinder, and then a resin having an average particle diameter of 150 µm to 850 µm was obtained using a sieve.

< Manufacturing example 2>

After adding 7.2 kg of 20% sodium hydroxide aqueous solution to 3.7 kg of acrylic acid, 11 g of ethoxyl-trimethylolpropane triacrylate as an internal crosslinking agent, and diphenyl (2,4,5-trimethylbenzoyl)-phos as a photoinitiator 1.2 g of pin oxide was added to prepare a water-soluble unsaturated monomer composition (neutralization degree of acrylic acid-based monomer: 70 mol%). Then, 37 g of sodium hydrogen carbonate was added to 333 g of water to prepare an aqueous sodium hydrogen carbonate solution. Subsequently, in a stirring tank, the water-soluble unsaturated monomer composition and the previously prepared aqueous sodium hydrogen carbonate solution were mixed and stirred at a speed of 250 rpm. Thereafter, a mixture of a water-soluble unsaturated monomer composition and aqueous sodium hydrogen carbonate solution was supplied to the belt surface of a belt-type continuous reactor having a width of 30 cm and a feed rate of 33 cm/min, and photopolymerization was performed after 20 seconds to obtain a sheet-like polymer. Was prepared. Next, the prepared sheet-like polymer was pulverized into particles through a meat chopper on a belt, and then dried in a hot air dryer at 170° C. for 40 minutes. The dried particulate polymer was pulverized once again using a cutting mill grinder, and then a resin having an average particle diameter of 150 µm to 850 µm) was obtained using a sieve.

< Comparative example 1>

After adding 7.2 kg of 20% sodium hydroxide aqueous solution to 3.7 kg of acrylic acid, 11 g of ethoxyl-trimethylolpropane triacrylate as an internal crosslinking agent, and diphenyl (2,4,5-trimethylbenzoyl)-phos as a photoinitiator 1.2 g of pin oxide was added to prepare a water-soluble unsaturated monomer composition (neutralization degree of acrylic acid-based monomer: 70 mol%). Subsequently, a water-soluble unsaturated monomer composition was supplied to the belt surface of a belt-type continuous reactor having a width of 30 cm and a feed rate of 33 cm/min, and photopolymerization was performed after 20 seconds to prepare a sheet-like polymer. Next, the prepared sheet-like polymer was pulverized into particles through a meat chopper on a belt, and then dried in a hot air dryer at 170° C. for 40 minutes. The dried particulate polymer was pulverized once again using a cutting mill grinder, and then a resin having an average particle diameter of 150 µm to 850 µm was obtained using a sieve.

< Comparative example 2>

The resin was prepared in the same manner as in Example 1, except that the water-soluble unsaturated monomer composition was first supplied to the belt surface of the belt-type continuous reactor, and sodium hydrogen carbonate powder was applied to the surface of the unsaturated monomer composition transferred by the belt after 10 seconds. Prepared and obtained.

< Comparative example 3>

After adding 7.2 kg of 20% sodium hydroxide aqueous solution to 3.7 kg of acrylic acid, 11 g of ethoxyl-trimethylolpropane triacrylate as an internal crosslinking agent, and diphenyl (2,4,5-trimethylbenzoyl)-phos as a photoinitiator 1.2 g of pin oxide was added to prepare a water-soluble unsaturated monomer composition (neutralization degree of acrylic acid-based monomer: 70 mol%). Then, 37 g of sodium hydrogen carbonate was added to 333 g of water to prepare an aqueous sodium hydrogen carbonate solution. Subsequently, the water-soluble unsaturated monomer composition was supplied to the belt-type continuous reactor at a flow rate of 1 kg/min through a supply line, and an aqueous sodium hydrogen carbonate solution was directly introduced into the unsaturated monomer composition supply line at a flow rate of 0.1 kg/min. Thereafter, the resin was prepared in the same manner as in Example 2, except that a mixture of a water-soluble unsaturated monomer composition and an aqueous sodium hydrogen carbonate solution was supplied to the belt surface of a belt-type continuous reactor having a width of 30 cm and a feed rate of 33 cm/min. Prepared and obtained.

< Comparative example 4>

A resin was prepared and obtained in the same manner as in Example 2, except that the water-soluble unsaturated monomer composition and the aqueous sodium hydrogen carbonate solution were not stirred in the stirring tank.

< Experimental example 1: Comparison of injection effect of blowing agent powder>

The water holding capacity (CRC), absorption capacity under pressure (AUP), and absorption rate (FSR) of the resins prepared and obtained according to Preparation Example 1, Comparative Example 1, and Comparative Example 2 were measured, and the results are shown in Table 1 below. . Analysis of water holding capacity and absorption capacity under pressure was performed according to EDANA (European Disposables and Nonwovens Association) WSP241.2.R3, EDANA WSP242.2.R3 methods. Analysis of the absorption rate was performed according to the vortex time measurement method.

Water holding capacity (g/g) Absorption capacity under pressure (g/g) Absorption rate (g/gs) Manufacturing Example 1 37 15 0.52 Comparative Example 1 38 15 0.37 Comparative Example 2 37 16 0.43

Referring to Table 1, it was confirmed that the resins of Preparation Example 1 and Comparative Example 2 prepared by adding the blowing agent powder had the same level of water holding capacity and absorption capacity under pressure as the resin of Comparative Example 2 without adding the blowing agent powder. I can.

In addition, in the manufacturing method using a belt-type continuous reactor, the water-soluble unsaturated monomer composition was first supplied to the belt surface, and the foaming agent powder was first applied to the belt surface, and then the foaming agent powder was applied to the surface of the belt. In the case of the resin of Preparation Example 1 supplied with the water-soluble unsaturated monomer composition, it can be seen that the absorption rate is further improved.

< Experimental example 2: Comparison of the injection effect of the aqueous foaming agent solution>

The water holding capacity, absorption capacity under pressure, and absorption rate of the resins prepared and obtained according to Preparation Example 2, Comparative Example 1, Comparative Example 3, and Comparative Example 4 were measured in the same manner as in Experimental Example 1, and the results are shown in Table 2 below. Indicated.

Water holding capacity (g/g) Absorption capacity under pressure (g/g) Absorption rate (g/gs) Manufacturing Example 2 38 15 0.69 Comparative Example 1 38 15 0.37 Comparative Example 3 38 16 0.37 Comparative Example 4 37 16 0.38

Referring to Table 2, in the case of the resins of Preparation Example 2, Comparative Example 3, and Comparative Example 4 prepared by adding an aqueous foaming agent solution, the water holding capacity and pressure were the same as those of the resin of Comparative Example 2 without the addition of the foaming agent aqueous solution. It can be confirmed that it has an absorption ability.

In addition, in the manufacturing method using a belt-type continuous reactor, the water-soluble unsaturated monomer composition and the foaming agent aqueous solution were strongly stirred compared to the resins of Comparative Examples 3 and 4 in which the water-soluble unsaturated monomer composition and the foaming agent aqueous solution were not stirred. In the case of the resin of Preparation Example 2, it can be seen that the absorption rate is further improved.

The embodiments of the present invention have been described above, but these are only examples and do not limit the present invention, and those of ordinary skill in the field to which the present invention pertains should not depart from the essential characteristics of the embodiments of the present invention. It will be appreciated that various modifications and applications not illustrated above are possible. For example, each component specifically shown in the embodiments of the present invention can be modified and implemented. And differences related to these modifications and applications should be construed as being included in the scope of the present invention defined in the appended claims.

1: monomer composition supply unit
2: Foaming agent powder supply unit
4, 4': transfer roll
5: belt
6: light irradiation unit
101: monomer composition
201: blowing agent powder
301: bubble-formed monomer composition
401: polymer

Claims (10)

Providing a blowing agent powder on the belt surface of the belt-type reactor;
Preparing a second composition by providing a first composition including a hydrophilic monomer, a crosslinking agent, and a polymerization initiator on the belt surface provided with the blowing agent powder; And
A method for producing a super absorbent polymer comprising the step of polymerizing the second composition on the belt-type reactor while providing the blowing agent powder and the first composition on the belt. delete delete delete delete delete delete The method of claim 1,
The second composition is a mixture containing air bubbles,
The step of polymerizing the second composition on the belt-type reactor is a step of forming a polymer having a pore structure by polymerizing a mixture containing the air bubbles. The method of claim 8,
After the step of forming a polymer having the pore structure,
Drying the polymer; And
A method for producing a super absorbent polymer further comprising the step of pulverizing the polymer. The method of claim 1,
The blowing agent powder is a method for producing a super absorbent polymer comprising sodium hydrogen carbonate (NaHCO ₃ ) and/or sodium carbonate (NaCO ₃ ).

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