KR20200076293A - Preparation method of spinning solution for super absorbent polymer resin fiber - Google Patents

Abstract

The present invention relates to a method for manufacturing a super absorbent resin fiber and a super absorbent resin fiber produced therefrom. According to the manufacturing method of the present invention, a super absorbent resin having a form of a fiber or a non-woven fabric while maintaining a super absorbency function of absorbing moisture can be manufactured.

Description

Manufacturing method of spinning solution for producing super absorbent polymer fiber{PREPARATION METHOD OF SPINNING SOLUTION FOR SUPER ABSORBENT POLYMER RESIN FIBER}

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

Super Absorbent Polymer (SAP) is a synthetic polymer material that has the ability to absorb about 500 to 1,000 times its own weight, and has been put into practical use as a physiological tool, and is now a paper diaper for children. In addition to sanitary products such as gardening, it is widely used as materials for soil repair agents for civil engineering, civil engineering, construction water supply materials, sheet for raising seedlings, freshness preservatives in the field of food distribution, and poultices. Therefore, it can be said that the market value of the superabsorbent polymer, which is known to have excellent absorbing capacity compared to conventional absorbent materials, is being broadened.

Current superabsorbent polymers are manufactured and used in powder form. The superabsorbent polymer in the form of a powder has a portion that may be scattered or leaked when manufacturing a hygiene material or in actual use, and is limited in scope of use because it must be used with a specific type of substrate.

Accordingly, in recent years, development of a superabsorbent polymer fiber having a fiber or nonwoven form while maintaining a superabsorbent function has been made. The superabsorbent polymer fiber has excellent permeability, absorption rate, and flexibility when compared to the existing powdered superabsorbent polymer, and can be used alone without a separate substrate. . In particular, in the application of the core layer of the sanitary material, a fluff pulp can be partially or completely replaced, thereby significantly reducing the volume of the sanitary material and enabling various designs. The superabsorbent polymer fibers may be prepared by using a spinning process such as centrifugal spinning, solution jetting, wet spinning, and electrospinning to prepare a solution containing a polymer in which a water-soluble ethylenically unsaturated monomer is polymerized.

On the other hand, since the monomer used in the preparation of the super absorbent polymer exhibits toxicity to the human body, it is essential to remove residual monomers that have not been polymerized. In general, when manufacturing a superabsorbent polymer in powder form, since the crosslinking agent is added together and polymerized, residual monomer control is relatively easy. However, in the case of manufacturing superabsorbent polymer fibers, in order to increase the processability and productivity of the spinning process, it is necessary to increase the solid content of the solution and lower the viscosity while increasing the molecular weight of the resin, so it may be more advantageous to use the spinning solution in a non-crosslinked state. have. For this reason, there are cases where a crosslinking agent is not used in solution polymerization, which results in a considerable amount of monomer remaining in the solution.

Usually, as a method for removing residual monomers when producing super absorbent polymer fibers, an aging process in which the spinning solution is left at a high temperature for a certain time, or a boosting process in which a small amount of an initiator is additionally added to the spinning solution is applied. have.

However, in the case of the aging process, the removal efficiency of residual monomers is low, and when the storage stability and thermal stability of the spinning solution are poor, there are disadvantages in that physical properties of the polymer in the spinning solution may change or unwanted crosslinking reactions may occur. In addition, when boosting using an initiator, the removal efficiency of residual monomers is high, but it is difficult to control the reaction, and if the initiator is not completely removed, problems such as discoloration, deterioration of stability, and changes in physical properties of the spinning solution may occur.

In order to solve the problems of the prior art as described above, the present invention can effectively remove the monomer remaining after the polymerization reaction, and excellent in storage stability to produce a spinning solution for producing a super absorbent polymer with little change in properties even during long-term storage It is an object of the present invention to provide a method for manufacturing a superabsorbent polymer fiber using the spinning solution.

The present invention to achieve the above object,

Preparing a polymer solution comprising a polymer in which a water-soluble ethylenically unsaturated monomer is polymerized;

Preparing a neutralized polymer solution by adding an alkali metal hydroxide to the polymer solution; And

A method of producing a spinning solution for producing a superabsorbent polymer fiber comprising the steps of: a) adding an aqueous solution of an initiator to the neutralized polymer solution and b) an aqueous solution of a reducing agent forming a redox couple with the initiator to remove residual monomers,

The a) aqueous solution of the initiator and b) the aqueous solution of the reducing agent are added dropwise in a range of 30 ppm or more to less than 500 ppm with respect to the neutralized polymer solution based on the weight of the initiator and the reducing agent, respectively.

The spinning solution, after storage for one week at 25 ℃ provides a method for producing a spinning solution for producing super absorbent polymer fibers, the viscosity change value of the solution is 2500 cP or less.

In the spinning solution, the content of the water-soluble ethylenically unsaturated monomer in 100% by weight may be 0.2% by weight or less.

The step of removing the residual monomers may include an aging process in which a) the initiator aqueous solution and b) the reducing agent aqueous solution are added dropwise for 30 minutes to 2 hours.

The concentrations of the a) initiator aqueous solution and b) aqueous reducing agent solution may be 0.5 to 5% by weight, respectively.

The initiator of a) may be at least one selected from the group consisting of sodium persulfate, potassium persulfate, and ammonium persulfate, wherein the reducing agent of b) is sodium metabisulfite (Na ₂ S ₂ O ₅ ); Tetramethyl ethylenediamine (TMEDA); A mixture of iron(II) sulfate and EDTA (FeSO ₄ /EDTA); Sodium formaldehyde sulfoxylate; And it may be at least one selected from the group consisting of disodium 2-hydroxy-2-sulfinoacetate (Disodium 2-hydroxy-2-sulfinoacteate).

The initiator of a) may be hydrogen peroxide, t-butyl hydroperoxide, or a combination thereof, wherein the reducing agent of b) is ascorbic acid (Ascorbic acid); Sucrose; Sodium sulfite (Na ₂ SO ₃ ) sodium metabisulfite (Na ₂ S ₂ O ₅ ); Tetramethyl ethylenediamine (TMEDA); A mixture of iron(II) sulfate and EDTA (FeSO ₄ /EDTA); Sodium formaldehyde sulfoxylate; Disodium 2-hydroxy-2-sulfinoacteate; And it may be at least one selected from the group consisting of disodium 2-hydroxy-2-sulfoacetate (Disodium 2-hydroxy-2-sulfoacteate).

The solid content of the spinning solution may be 20 to 60%.

The degree of neutralization of the spinning solution may be 30 to 90 mol%.

The weight average molecular weight of the polymer contained in the spinning solution may be 50,000 to 200,000 g/mol.

In addition, the present invention, adding a crosslinking agent to the spinning solution; And

It provides a method for producing a superabsorbent polymer fiber comprising the step of drying the spinning solution is added to the crosslinking agent after centrifugal spinning.

According to the present invention, it is possible to effectively remove residual monomers in the spinning solution while inhibiting the crosslinking reaction without harming the physical properties such as viscosity of the spinning solution, molecular weight and molecular weight distribution of the polymer. In addition, the spinning solution for producing superabsorbent polymer fibers prepared according to the present invention has excellent storage stability, and can realize stable physical properties even during long-term storage.

In addition, according to the manufacturing method of the superabsorbent polymer fiber of the present invention, the superabsorbent polymer fiber having the form of a fiber while maintaining the superabsorbent function of absorbing a much larger amount of water than its own weight, without fear of scattering or leaking Can be produced.

The terms used in this specification are only used to describe exemplary embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, the terms "include", "have" or "have" are intended to indicate that an implemented feature, step, component, or combination thereof exists, one or more other features or steps, It should be understood that the possibility of the presence or addition of components, or combinations thereof, is not excluded in advance.

The present invention can be applied to various changes and may have various forms, and specific embodiments will be illustrated and described in detail below. However, this is not intended to limit the present invention to a specific disclosure form, and it should be understood that all modifications, equivalents, and substitutes included in the spirit and scope of the present invention are included.

Hereinafter, a method of manufacturing a spinning solution for producing super absorbent polymer fibers according to a specific embodiment of the present invention will be described in more detail.

According to an embodiment of the present invention, preparing a polymer solution comprising a polymer in which a water-soluble ethylenically unsaturated monomer is polymerized; Preparing a neutralized polymer solution by adding an alkali metal hydroxide to the polymer solution; And a) adding an aqueous solution of the initiator and b) an aqueous solution of a reducing agent forming a redox couple with the initiator to the neutralized polymer solution to remove residual monomer, wherein the a ) Initiator aqueous solution and b) reducing agent aqueous solution are added dropwise in the range of 30 ppm or more to less than 500 ppm with respect to the neutralized polymer solution based on the weight of the initiator and reducing agent, respectively, and the spinning solution is stored at 25° C. for one week. A method for producing a spinning solution for producing superabsorbent polymer fibers is provided, wherein the viscosity change value of the post-solution is 2500 cP or less.

First, a polymer solution is prepared by polymerizing a water-soluble ethylenically unsaturated monomer.

In the method for producing a superabsorbent polymer fiber according to the present invention, the water-soluble ethylenically unsaturated monomer is not particularly limited as long as it is a monomer commonly used in the production of superabsorbent polymers, but preferably anionic monomers, salts, and nonionics Any one or more selected from the group consisting of a system hydrophilic monomer and an amino group-containing unsaturated monomer and a quaternary product thereof can be used.

Specifically, isobutylene, acrylic acid, polyacrylic acid, methacrylic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, 2-acryloylethanesulfonic acid, 2-methacryloylethanesulfonic acid, 2-(meth)acrylic Roylpropanesulfonic acid, or anionic monomers of 2-(meth)acrylamide-2-methylpropane sulfonic acid and salts thereof; (Meth)acrylamide, N-substituted (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, methyl acrylate, hydroxypropyl methacrylate, methoxy A nonionic hydrophilic monomer containing polyethylene glycol (meth)acrylate or polyethylene glycol (meth)acrylate; And an amino group-containing unsaturated monomer of (N, N)-dimethylaminoethyl (meth)acrylate or (N, N)-dimethylaminopropyl (meth)acrylamide, and quaternaries thereof. Can be used.

Moreover, it is more preferable that it is at least one selected from the group consisting of isobutylene, maleic anhydride, polyacrylic acid, acrylic acid, methyl acrylate, and hydroxypropyl methacrylate.

Most preferably, acrylic acid or a salt thereof can be used, and when acrylic acid or a salt thereof is used as a monomer, there is an advantage in that a superabsorbent polymer fiber having improved absorbency can be obtained.

According to an embodiment of the present invention, the water-soluble ethylenically unsaturated monomer and the polymerization initiator are dissolved in water to make a monomer composition in an aqueous solution state, and the water-soluble ethylenically unsaturated monomer is subjected to thermal polymerization or photopolymerization with respect to the monomer composition. It is possible to obtain a polymer solution comprising a polymerized polymer.

At this time, the polymerization initiator used in the polymerization is not particularly limited as long as it is generally used for the production of super absorbent polymers.

Specifically, the polymerization initiator may be a thermal polymerization initiator or a photopolymerization initiator according to UV irradiation depending on the polymerization method. However, even by the photopolymerization method, since a certain amount of heat is generated by irradiation with ultraviolet rays or the like and a certain amount of heat is generated as the polymerization reaction that is an exothermic reaction proceeds, a thermal polymerization initiator may be additionally included.

If the photopolymerization initiator is a compound capable of forming a radical by light such as ultraviolet rays, the composition may be used without limitation.

Examples of the photopolymerization initiator include benzoin ether, dialkyl acetophenone, hydroxyll alkylketone, phenyl glyoxylate, and benzyl dimethyl ketal. ketal), acyl phosphine, and alpha-aminoketone. Meanwhile, as a specific example of acylphosphine, a commercially available lucirin TPO, that is, 2,4,6-trimethyl-benzoyl-trimethyl phosphine oxide (2,4,6-trimethyl-benzoyl-trimethyl phosphine oxide) can be used. . For a wider variety of photoinitiators, it is well documented in Reinhold Schwalm's book "UV Coatings: Basics, Recent Developments and New Application (Elsevier 2007)" p115, and is not limited to the examples described above.

In addition, as the thermal polymerization initiator, one or more selected from the initiator group consisting of a persulfate-based initiator, an azo-based initiator, hydrogen peroxide, and ascorbic acid may be used. Specifically, examples of the persulfate-based initiator are sodium persulfate (Na ₂ S ₂ O ₈ ), potassium persulfate (K ₂ S ₂ O ₈ ), ammonium persulfate (Ammonium persulfate; (NH ₄ ) ₂ S ₂ O ₈ ), and examples of the azo-based initiator are 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-azobis[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)). More various thermal polymerization initiators are well specified in the Odian book'Principle of Polymerization (Wiley, 1981)', p203, and are not limited to the examples described above.

The temperature of the polymerization reaction may be appropriately adjusted depending on the type of monomer and initiator used, but may be, for example, 40 to 90°C, or 60 to 80°C.

The polymer solution contains a polymer prepared by polymerizing the aforementioned water-soluble ethylenically unsaturated monomer. At this time, the polymer is meant to include not only a polymer in which one type of monomer is polymerized, but also a polymer in which two or more types of monomers are copolymerized.

The polymer may be a non-crosslinked polymer polymerized without a crosslinking agent, or a crosslinked polymer polymerized with a crosslinking agent.

In one embodiment of the present invention, the polymer may be a polymer in a non-crosslinked state, in which case a crosslinked superabsorbent polymer fiber is spun by adding a crosslinking agent to a spinning solution containing a polymer in a non-crosslinked state, as described below. Can be produced.

If the polymer is a crosslinked polymer, a polymerization reaction may be further performed by further including a crosslinking agent in the monomer composition. At this time, as a crosslinking agent, materials used for crosslinking of water-soluble ethylenically unsaturated monomers, which are usually used in the manufacture of super absorbent polymers, can be used without limitation. Specifically, a crosslinking agent described later may be used as a crosslinking agent added to a spinning solution containing a polymer in an uncrosslinked state.

The weight average molecular weight of the polymer in which the water-soluble ethylenically unsaturated monomer is polymerized is not particularly limited, but may range from about 50,000 to about 200,000 g/mol, preferably from about 100,000 to about 150,000 g/mol. However, this may vary depending on the viscosity of the polymer solution and the solid content of the polymer.

The polymer solution containing the polymer may be adjusted to have a concentration (solid content) of the polymer of about 20 to about 60% by weight, or about 40 to about 50% by weight in consideration of process ease and economy.

Next, an alkali metal hydroxide is added to the polymer solution to prepare a neutralized polymer solution.

At this time, as the alkali metal hydroxide, sodium hydroxide (NaOH) or potassium hydroxide (KOH) may be used.

The alkali metal hydroxide is preferably added so that the neutralization degree of the polymer solution is about 30 to about 90 mol%, preferably about 50 to about 90 mol%, more preferably about 70 to about 80 mol%. In the present invention, the neutralization degree is a value calculated by an equation calculated when measuring a water-soluble component.

If the degree of neutralization is too low, the osmotic pressure is low due to a small number of functional groups ionized in the polymer, and if the degree of neutralization is high, the osmotic pressure is increased, but the number of crosslinkable functional groups may be reduced due to a decrease in the number of crosslinkable functional groups. It is desirable to have a degree of neutralization.

Next, a step of removing residual monomers is performed by dropwise adding a) an aqueous initiator solution and b) an aqueous reducing agent forming a redox couple with the initiator to the neutralized polymer solution.

In the existing method for producing superabsorbent polymer fibers, for the removal of residual monomer after polymerization, the spinning solution is left at a high temperature (based on the polymerization reaction temperature, at an elevated temperature of 10 to 20 ^o C) for a certain period of time or an aqueous solution of initiator A small boosting process was used. However, in the case of such a method, not only the effect of removing residual monomers is insufficient, but also the properties of the spinning solution are changed, so that there is a problem that the physical properties of the superabsorbent polymer fiber cannot be guaranteed.

Accordingly, in the present invention, the initiator and the reducing agent forming the redox couple are introduced into the solution phase to effectively remove residual monomers, while maintaining physical properties of the spinning solution.

Specifically, the initiator and the reducing agent react with each other when they are added to the neutralized polymer solution to form radicals. The radicals formed react with the monomers remaining in the polymer solution, thereby removing residual monomers. Since the oxidation-reduction reaction between the initiator and the reducing agent is very high, efficient residual monomer removal is possible even if only a small amount of the initiator and the reducing agent is added, and there is no need to increase the process temperature, thereby minimizing the physical property change of the polymer solution. .

The reaction for removing residual monomers using the oxidation-reduction reaction may occur smoothly even at a temperature near room temperature (25°C). However, when the solid content and the weight average molecular weight of the polymer solution are high, when the process temperature is too low, diffusion of radicals and residual monomers is lowered and effective removal of residual monomers may be difficult.

Thus, in the present invention, the step of removing the residual monomer may be appropriately adjusted according to the type of the monomer and the initiator and the reducing agent used, but may be performed at a temperature of 10 to 60 ^o C lower than the temperature of the polymerization reaction. Preferably it can be carried out at a temperature of 20 to 40 ^o C lower than the temperature of the polymerization reaction. That is, the addition of the a) aqueous solution of the initiator and b) the aqueous solution of the reducing agent is performed within the temperature range.

In this case, the concentrations of the a) aqueous solution of the initiator and b) the aqueous solution of the reducing agent may be 0.5 to 5% by weight, respectively. As described above, since the reactivity between the initiator and the reducing agent is very high, it is preferable that the aqueous initiator solution and the reducing agent aqueous solution are diluted and used as much as possible. However, in order to maximize the solid content of the spinning solution, a range of 1 to 2% by weight may be more preferable. When the concentration of the aqueous solution of the initiator and the solution of the reducing agent satisfies the above range, uniform mixing with the polymer solution is possible, and the change in the molecular weight distribution (PDI) of the polymer in the solution before and after the residual monomer removal step and the viscosity change of the solution can be minimized. have.

The a) the aqueous solution of the initiator and b) the aqueous solution of the reducing agent may cause excessive reaction when temporarily added, and since radicals formed before reacting with all monomers remaining in the solution may be destroyed, dropwise is added to the neutralized polymer solution. It is preferred to do so in a manner. The dropping time is not particularly limited, but is preferably performed for 30 to 150 minutes, or 60 to 120 minutes, since it is possible to secure a smooth monomer removal effect.

At this time, in order to further increase the removal efficiency of the residual monomers, an aging process in which the a) initiator aqueous solution and b) the reducing agent aqueous solution are added dropwise for 30 minutes to 2 hours can be further performed.

The a) initiator contained in the initiator aqueous solution can be used without limitation, a conventional thermal polymerization initiator. At this time, the initiator used in the polymerization step of the water-soluble ethylenically unsaturated monomer and the initiator used in the residual monomer removal step are not necessarily the same. Further, b) the reducing agent contained in the reducing agent aqueous solution is not particularly limited as long as it is a substance capable of reducing the initiator used, but is preferably a substance capable of reducing both the initiator used in the polymerization step and the initiator used in the residual monomer removal step. Do. Initiators and reducing agents used in the residual monomer removal step may be appropriately selected according to the purpose of use of the superabsorbent polymer to be produced.

In one embodiment, the initiator a) contained in the initiator aqueous solution may be used one or more persulfate-based initiators selected from the group consisting of sodium persulfate, potassium persulfate, and ammonium persulfate.

When a persulfate-based initiator is used as above, the reducing agent of b) is sodium metabisulfite (Na ₂ S ₂ O ₅ ); Tetramethyl ethylenediamine (TMEDA); A mixture of iron(II) sulfate and EDTA (FeSO ₄ /EDTA); Sodium formaldehyde sulfoxylate; And disodium 2-hydroxy-2-sulfinoacteate. At least one selected from the group consisting of disodium 2-hydroxy-2-sulfinoacteate may be used.

In one example, potassium persulfate is used as the initiator and disodium 2-hydroxy-2-sulfinoacetate is used as the reducing agent; Ammonium persulfate as an initiator and tetramethylethylenediamine as a reducing agent; Sodium persulfate can be used as an initiator, and sodium formaldehyde sulfoxylate can be used as a reducing agent. When the redox couple as described above is used, discoloration and gelation of the spinning solution does not occur, and stable physical properties can be maintained even for long-term storage.

In another embodiment, the initiator of a) may be a hydrogen peroxide-based initiator, specifically hydrogen peroxide, t-butyl hydroperoxide, or a combination thereof.

When using a hydrogen peroxide-based initiator as described above, the reducing agent of b) is ascorbic acid; Sucrose; Sodium sulfite (Na ₂ SO ₃ ) sodium metabisulfite (Na ₂ S ₂ O ₅ ); Tetramethyl ethylenediamine (TMEDA); A mixture of iron(II) sulfate and EDTA (FeSO ₄ /EDTA); Sodium formaldehyde sulfoxylate; Disodium 2-hydroxy-2-sulfinoacteate; And it may be at least one selected from the group consisting of disodium 2-hydroxy-2-sulfoacetate (Disodium 2-hydroxy-2-sulfoacteate).

In one example, t-butylhydroperoxide is used as an initiator, and disodium 2-hydroxy-2-sulfinoacetate is used as a reducing agent; Hydrogen peroxide as an initiator and ascorbic acid as a reducing agent; When t-butyl hydroperoxide is used as the initiator and sodium formaldehyde sulfoxylate is used as the reducing agent, discoloration and gelation of the spinning solution does not occur, and stable physical properties can be maintained even for long-term storage, which may be preferable.

The a) the aqueous solution of the initiator and b) the aqueous solution of the reducing agent, based on the weight of the initiator and the reducing agent, respectively, in the range of 30 ppm or more to less than 500 ppm, or 50 to 300 ppm, or 100 to 200 ppm, relative to the neutralized polymer solution. Become enemy That is, the total amount of initiator used in the residual monomer removal step is 30 ppm or more to less than 500 ppm for the neutralized polymer solution, and the reducing agent is used in a range of 30 ppm or more to less than 500 ppm for the neutralized polymer solution.

If the input amount of the initiator and the reducing agent is less than 30 ppm, a sufficient reaction may not occur and the monomer removal effect may be deteriorated, and if it exceeds 500 ppm, the monomer removal effect may be obtained, but there is a fear of discoloration and spinning solution deterioration. It is desirable to satisfy.

The spinning solution prepared through the monomer removal step as described above may have a content of water-soluble ethylenically unsaturated monomer of 100% by weight or less, or 0.18% by weight or less, or 0.15% by weight or less.

According to the manufacturing method of the present invention, a change in physical properties of a polymer and a polymer solution in a residual monomer removal process can be minimized.

Thus, the spinning solution prepared according to the present invention maintains the concentration (solid content) of the polymer at about 20 to about 60% by weight, or about 40 to about 50% by weight, as well as the polymer solution before the residual monomer removal process, and neutralizes Is maintained at 30 to 90 mol%, or 50 to 90 mol%, or 70 to 80 mol%. In addition, the weight average molecular weight of the polymer in which the water-soluble ethylenically unsaturated monomer is polymerized in the spinning solution satisfies the range of 50,000 to 200,000 g/mol.

In particular, according to the manufacturing method of the present invention, since the storage stability of the spinning solution is excellent, it is possible to provide a spinning solution with little change in physical properties even for long-term storage. Specifically, the spinning solution prepared by the above method has a viscosity change value of 2500 cP or less, or 2300 cP or less, or 2200 cP or less after storage at 25°C for one week. The lower the viscosity change value, the more advantageous. In theory, it may be 0 cP, but may be, for example, 500 cP or more, or 1000 cP or more.

The viscosity change value may be measured by measuring and comparing the viscosity of the spinning solution immediately after preparation at 25°C and the viscosity of the spinning solution after storage at 25°C for one week, and the viscosity is Brookfield RVDV3T viscometer. It can be measured using. Specifically, the sample is transferred to a sample chamber of 13 mL, the temperature is adjusted to 25° C., the spindle is fixed to the sample chamber, the rotational speed of the spindle is fixed at 3 to 20 rpm, or more than 20 minutes or until the value stabilizes. It can be measured by reading and recording the final value.

The spinning solution prepared as described above can be suitably used for the production of super absorbent polymer fibers.

Thus, according to another embodiment of the present invention, adding a crosslinking agent to the spinning solution prepared by the method of the present invention; And it is provided a method for producing a superabsorbent polymer fiber comprising the step of drying after spinning the spinning solution is added to the crosslinking agent.

In one embodiment of the present invention, a polymer is prepared without adding a crosslinking agent in a step of preparing a polymer solution, and then a crosslinking agent is added to the spinning solution containing the non-crosslinked polymer, and then centrifuged to spin it, in a spinning process. Allow crosslinking of the uncrosslinked polymer to occur. In this case, the solid content and molecular weight can be improved under the viscosity of the same spinning solution, thereby improving productivity and processability, and also improving absorption properties.

The crosslinking agent is, for example, a polyhydric alcohol compound; (Meth)acrylate-based compounds; Hydroxy alkyl (meth)acrylate-based compounds; Epoxy compounds; Polyamine compounds; Halo epoxy compounds; Condensation products of halo epoxy compounds; Oxazoline compounds; Mono-, di- or polyoxazolidinone compounds; Cyclic urea compounds; Polyvalent metal salts; And it may use 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 selected from the group consisting of 1,2-cyclohexanedimethanol can be used.

Further, as an example of the (meth)acrylate-based compound, poly(ethylene glycol) diacrylate may be used.

In addition, ethylene glycol diglycidyl ether and glycidol may be used as the epoxy compound, and ethylenediamine, diethylenetriamine, triethylenetetraamine, tetraethylenepentamine, and pentaethylenehexamine may be used as polyamine compounds. , Polyethyleneimine and polyamide polyamine may be used.

And, as the halo epoxy compound, epichlorohydrin, epibromohydrin, and α-methylepichlorohydrin can be used. Meanwhile, as the mono-, di- or polyoxazolidinone compound, for example, 2-oxazolidinone or the like can be used. And, as the alkylene carbonate compound, ethylene carbonate or the like can be used. These may be used alone or in combination with each other. On the other hand, in order to increase the efficiency of the crosslinking process, it is preferable to use one or more polyhydric alcohol compounds, and more preferably, polyhydric alcohol compounds having 2 to 10 carbon atoms can be used.

The content of the crosslinking agent may be appropriately selected depending on the type of crosslinking agent added or reaction conditions, but in order to induce an appropriate crosslinking reaction, the molar ratio of the polymer and the crosslinking agent is about 95: 5 to about 99.9: 0.1, or about 97 : 3 to about 99.9: 0:1, or about 98: 2 to about 99.9: 0:1.

Next, the spinning solution in which the crosslinking agent is mixed is put into a spinnerette, centrifugally spun, and dried to prepare superabsorbent polymer fibers.

The centrifugal spinning puts the polymer in a molten or solution state into a spinneret with a large number of holes, rotates at a high speed, and stretches the unsolidified polymer by using the centrifugal force acting at this time, and stacks the solidified fibers on the collector. The fibers thus produced by the method are obtained in the form of a nonwoven fabric. Centrifugal spinning has the advantages of simple equipment configuration, low energy consumption, fewer restrictions on polymers that can be used, and simplification of the process because it is manufactured in the form of a non-woven fabric by spinning directly onto the base.

In one embodiment of the present invention, the rotational speed during the centrifugal spinning may be about 3,000 rpm to about 15,000 rpm, but is not limited thereto. When centrifugal spinning at the rotational speed, since the spinning solution can be spun directly onto a substrate, it has the advantage of simplifying the process.

In addition, the hole size of the spinneret may be about 100 to about 1,000㎛, or about 200 to about 800㎛, but is not limited thereto.

As described above, drying is performed immediately after centrifugal spinning of the spinning solution.

The drying may be performed at a drying temperature of about 100 to about 250°C, or about 190 to about 250°C for about 10 minutes to about 120 minutes.

Meanwhile, the drying temperature may be defined as a temperature of a heating medium supplied for drying or a drying reactor including a heating medium and a polymer in a drying process. When the drying temperature is less than 100°C, the drying time is too long and there is a fear that the physical properties of the superabsorbent polymer fibers to be finally formed are deteriorated. When the drying temperature exceeds 250°C, only the fiber surface is dried excessively, resulting in final formation. There is a concern that the physical properties of the superabsorbent polymer fibers are deteriorated. Preferably, the drying may be carried out at a temperature of about 100 ℃ to about 250 ℃, more preferably at a temperature of about 160 ℃ to about 220 ℃.

In addition, in the case of the drying time, the configuration is not limited, but may be performed for 10 minutes to 120 minutes, more preferably 20 minutes to 90 minutes in consideration of process efficiency and the like.

In addition, the drying method of the drying step may also be selected and used without limitation in configuration, as long as it is commonly used as a drying process. Specifically, the drying step may be performed by a method such as hot air supply, infrared irradiation, microwave irradiation, or ultraviolet irradiation.

In one embodiment of the present invention, the fiber is preferably a non-woven fabric, but is not limited thereto.

The superabsorbent polymer fibers according to the present invention can be suitably used for sanitary products or resin molded products. Here, the resin molded article may include the resin fiber of the embodiment, or may be made of only such resin fiber.

The use of the resin molded article is not particularly limited, and may encompass molded articles used in various fields such as medicine, chemical, chemical, food or cosmetics.

In addition, according to another embodiment of the present invention provides a superabsorbent polymer fiber produced by the above manufacturing method.

The superabsorbent polymer fiber has high absorbency against moisture in a non-pressurized or pressurized environment, and at the same time exhibits flexibility and processability, and thus can be modified in various shapes, thereby allowing a wider range of applications.

Hereinafter, the present invention will be described in more detail based on Examples, but the embodiments of the present invention disclosed below are merely examples, and the scope of the present invention is not limited to these embodiments. The scope of the invention is indicated in the claims, and furthermore, includes all changes within the meaning and scope equivalent to the claims of the claims. In addition, "%" and "part" showing content in the following Examples and Comparative Examples are based on mass unless otherwise specified.

<Example>

Preparation of spinning solution

Example 1

28.42 g of water was added to the reactor, the temperature was raised to 80° C., and nitrogen gas was purged for 50 minutes, and 6 g of a 0.5% by weight aqueous potassium persulfate solution was added. Next, 50 g of acrylic acid, 9 g of a 3 wt% aqueous solution of 2-mercaptoethanol as a chain transfer agent, and 30 g of 0.5 wt% potassium persulfate as a polymerization initiator were prepared, and these components were continuously introduced into the reactor for 4 hours. A polymer aqueous solution containing 48% by weight of polyacrylic acid (Mw = 1.04 * 10 ⁵ g/mol) was prepared by reacting.

The neutralization degree was adjusted to 70 mol% by adding 40% caustic soda (NaOH) aqueous solution to 103.54 g of the polymer aqueous solution.

Separately, 0.5 g of a 1% aqueous solution of potassium persulfate as an initiator aqueous solution for removing residual monomers and a 1% aqueous solution of disodium 2-hydroxy-2-sulfinoacetate as a reducing agent aqueous solution were prepared, and each initiator and reducing agent content was Prepared to be 100 ppm of the aqueous polymer solution. Then, while maintaining the neutralized aqueous polymer solution at 60 ^° C., the aqueous initiator solution and the aqueous reducing agent solution were simultaneously added dropwise over 1 hour. Then, the temperature was maintained at 60 ^° C. for 2 hours to proceed with aging to prepare a spinning solution for producing super absorbent polymer fibers.

Example 2

A spinning solution for preparing superabsorbent polymer fibers was prepared in the same manner as in Example 1, except that 0.5 g of a 0.01% aqueous solution of t-butylhydroperoxide (TBHP) was used as an initiator aqueous solution (TBHP 100 ppm).

Example 3

A spinning solution for producing super absorbent polymer fibers was prepared in the same manner as in Example 1, except that 0.5 g (TMEDA 100 ppm) of a 0.01% aqueous solution of tetramethyl ethylenediamine (TMEDA) was used as the reducing agent aqueous solution.

Comparative Example 1

The neutralized polymer aqueous solution of Example 1 was used as Comparative Example 1.

Comparative Example 2

The neutralized polymer aqueous solution of Example 1 was aged at 90° C. for 2 hours to prepare a spinning solution of Comparative Example 2.

Comparative Example 3

A spinning solution for preparing superabsorbent polymer fibers was prepared in the same manner as in Example 1, except that 200 ppm of potassium persulfate was added while maintaining the neutralized polymer aqueous solution of Example 1 at 80 ^° C.

Comparative Example 4

The spinning solution of Comparative Example 4 was prepared in the same manner as in Example 1, except that the initiator aqueous solution and the reducing agent aqueous solution were added so that the initiator and reducing agent contents were 500 ppm relative to the aqueous polymer solution, respectively.

<Experimental Example>

(1) Measurement of residual monomer content

Residual monomer content was measured through general gas chromatography/flame ionization detector (GC/FID, EQC-0270) analysis. After dissolving 1 g of sample in 1 mL of distilled water, the resin component is precipitated by mixing with 9 mL of acetonitrile and centrifuged to filter the supernatant. Inject the sample into the sample inlet and heat it to 250 ^o C and flow it through the UV-531 column (0.53 mm ID x 30 mL) with 4 mL/min helium gas. The amount of residual monomer is determined by comparing the chromatogram obtained by the above method with the chromatogram of acrylic acid.

(2) Sulfur change and gelation measurement

The appearance immediately after preparation of the spinning solution and after one week of storage was visually observed to confirm the yellowing. In addition, after storing the spinning solution for a week, it was determined whether gelation was observed by observing whether gel particles precipitated in the solution or whether layer separation occurred.

(3) Measurement of viscosity change rate

As described above, the viscosity was measured immediately after preparation of the polymerized spinning solution by a measurement method using a Brookfield RVDV3T viscometer. And after the spinning solution was stored at room temperature for a week, the viscosity change rate was evaluated by measuring the viscosity again in the same manner.

(5) Weight average molecular weight (Mw) and molecular weight distribution (PDI) change rate measurement

Through GPC (Alliance 1200 Series) analysis, the rate of change of the weight average molecular weight (Mw) and molecular weight distribution (PDI) was measured by the following method.

Each 1 mg sample and 1 mg polyacrylic acid are mixed with a pH 7, 0.1 M NaNO ₃ buffer solvent. The sample connection the mixture of polyacrylic acid and 0.1 mL each of the mixed solution ultrahydrogel Linear column, and obtains a weight-average molecular weight and molecular weight distribution from the chromatogram obtained given flow at a rate of 1 mL / min at 40 ^o C.

Table 1 and 2 show the results of the experiment. In Table 2,'treatment' refers to the step of removing residual monomers.

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Residual monomer content (%) 0.13 0.15 0.23 0.9 0.5 0.4 0.11 Yellow change X X X X X X O Gelation X X X X X X X

Example 1 Example 2 Example 3 Comparative Example 2 Comparative Example 3 Comparative Example 4 25 ℃ viscosity
(cP) Before treatment 8,400 After treatment 10,300 10,200 10,200 11,800 9,700 11,500 Viscosity change after storage at 25 ℃ for 1 week (cP) +2,100 +2,400 +2,300 +9,500 +7,700 +2,400 Mw Before treatment 1.04 * 10 ⁵ After treatment 1.12 * 10 ⁵ 1.12 * 10 ⁵ 1.11 * 10 ⁵ 1.34 * 10 ⁵ 1.13 * 10 ⁵ 1.27 * 10 ⁵ PDI Before treatment 3.21 After treatment 3.38 3.36 3.34 3.98 3.35 3.44

Referring to Tables 1 and 2, the spinning solution prepared according to the present invention has less residual monomer content, no yellowing or gelling, compared to when the residual monomer is removed by the conventional treatment method, and the residual solution After the monomer removal step, it can be confirmed that various physical properties such as viscosity, weight average molecular weight, and molecular weight distribution were maintained. In addition, even after long-term storage, it is confirmed that the viscosity change is small, and thus the storage stability is excellent.

On the other hand, from the results of Comparative Example 4, when the amount of the initiator aqueous solution and the reducing agent aqueous solution is too large, the residual monomer removal effect is excellent, but it can be confirmed that yellowing occurs.

Claims (12)

Preparing a polymer solution comprising a polymer in which a water-soluble ethylenically unsaturated monomer is polymerized;
Preparing a neutralized polymer solution by adding an alkali metal hydroxide to the polymer solution; And
A method of producing a spinning solution for producing a superabsorbent polymer fiber comprising the steps of: a) adding an aqueous solution of an initiator to the neutralized polymer solution and b) an aqueous solution of a reducing agent forming a redox couple with the initiator to remove residual monomers,
The a) aqueous solution of the initiator and b) the aqueous solution of the reducing agent are added dropwise in a range of 30 ppm or more to less than 500 ppm with respect to the neutralized polymer solution based on the weight of the initiator and the reducing agent, respectively.
The spinning solution is a method for producing a spinning solution for producing super absorbent polymer fibers having a viscosity change value of 2500 cP or less after storage at 25° C. for one week.
According to claim 1,
The spinning solution, the content of the water-soluble ethylenically unsaturated monomer in 100% by weight is less than 0.2% by weight, a method for producing a spinning solution for producing super absorbent polymer fibers.
According to claim 1,
The step of removing the residual monomers includes a) an aging process that is left for 30 minutes to 2 hours after the dropwise addition of the aqueous solution of the initiator and the aqueous solution of the reducing agent, the method for producing a spinning solution for producing super absorbent polymer fibers.
According to claim 1,
The a) initiator aqueous solution and b) the concentration of the reducing agent aqueous solution is 0.5 to 5% by weight, respectively, a method for producing a spinning solution for producing super absorbent polymer fibers.
According to claim 1,
The initiator of a) is at least one selected from the group consisting of sodium persulfate, potassium persulfate, and ammonium persulfate, a method for producing a spinning solution for producing super absorbent polymer fibers.
The method of claim 5,
The reducing agent of b) is sodium metabisulfite (Na ₂ S ₂ O ₅ ); Tetramethyl ethylenediamine (TMEDA); A mixture of iron(II) sulfate and EDTA (FeSO ₄ /EDTA); Sodium formaldehyde sulfoxylate; And Disodium 2-hydroxy-2-sulfinoacetate (Disodium 2-hydroxy-2-sulfinoacteate) at least one selected from the group consisting of, a method for producing a spinning solution for producing super absorbent polymer fibers.
According to claim 1,
The initiator of a) is hydrogen peroxide, t-butyl hydroperoxide, or a combination thereof, a method for producing a spinning solution for producing super absorbent polymer fibers.
The method of claim 7,
The reducing agent of b) is ascorbic acid; Sucrose; Sodium sulfite (Na ₂ SO ₃ ) sodium metabisulfite (Na ₂ S ₂ O ₅ ); Tetramethyl ethylenediamine (TMEDA); A mixture of iron(II) sulfate and EDTA (FeSO ₄ /EDTA); Sodium formaldehyde sulfoxylate; Disodium 2-hydroxy-2-sulfinoacteate; And Disodium 2-hydroxy-2-sulfoacetate (Disodium 2-hydroxy-2-sulfoacteate) at least one selected from the group consisting of, a method for producing a spinning solution for producing super absorbent polymer fibers.
According to claim 1,
Solid content of the spinning solution is 20 to 60%, a method for producing a spinning solution for producing super absorbent polymer fibers.
According to claim 1,
The degree of neutralization of the spinning solution is 30 to 90 mol%, a method for producing a spinning solution for producing super absorbent polymer fibers.
According to claim 1,
Method of producing a spinning solution for producing a super absorbent polymer fiber, the weight average molecular weight of the polymer contained in the spinning solution is 50,000 to 200,000 g/mol.
Adding a crosslinking agent to the spinning solution of claim 1; And
Method for producing a super absorbent polymer fiber comprising the step of drying after spinning the spinning solution is added to the crosslinking agent.