KR102652392B1 - Super absorbent polymer fiber coated with polymer and method for preparing the same - Google Patents

Abstract

The present invention relates to polymer-coated superabsorbent resin fibers and a method for producing the same. According to the present invention, it is possible to provide a superabsorbent resin fiber with improved liquid permeability without deteriorating physical properties such as water retention capacity and absorbency under pressure.

Description

{Super absorbent polymer fiber coated with polymer and method for preparing the same}

The present invention relates to polymer-coated superabsorbent resin fibers and a method for producing the same.

Super Absorbent Polymer (SAP) is a synthetic polymer material that has the ability to absorb moisture 500 to 1,000 times its own weight. It began to be commercialized as sanitary products and is currently used as paper diapers for children. In addition to sanitary products, it is widely used as a material for soil repair agents for horticulture, waterproofing materials for civil engineering and construction, sheets for seedlings, freshness maintainers in the food distribution field, and fomentations. Therefore, compared to existing absorbents, superabsorbent polymers, which are known to have excellent absorption ability, can be said to have a high market value as their application range is gradually expanding.

Most current superabsorbent polymers are manufactured and used in powder form. Such powder-type superabsorbent polymers may scatter or leak when manufacturing sanitary materials or during actual use, and because they must be used with a specific type of substrate, their range of use is limited.

Accordingly, a method of manufacturing superabsorbent polymer in the form of fiber has recently been proposed. For example, in Korean Patent Publication No. 2017-0110947, a water-soluble ethylenically unsaturated monomer and a cross-linking agent are polymerized to prepare a polymer aqueous solution containing a polymer polymerized with the water-soluble ethylenically unsaturated monomer and a cross-linking agent, and sodium hydroxide is added to the polymer aqueous solution. A method for producing a superabsorbent polymer fiber is disclosed, which includes preparing a spinning solution neutralized by adding the spinning solution, centrifugally spinning the spinning solution, and then drying the spinning solution. However, the method disclosed in the Korean patent application is to manufacture superabsorbent resin fibers using a centrifugal spinning method. Due to the manufacturing characteristics, mass production is difficult, so productivity is low and fibers with a diameter of 10 μm or more cannot be manufactured, so the absorption rate and transmission rate are low. It has disadvantages such as reduced permeability.

Meanwhile, most sanitary materials currently in circulation are composed of highly absorbent particles and cellulose-based or polyester-based fibers, commonly known as pulp. Pulp, which accounts for 30 to 50% of the total weight of sanitary materials, has no liquid absorbency. It is absent or at a very low level.

Therefore, if absorbent and fibrous resin is used as a substitute for pulp, the proportion of superabsorbent resin in sanitary products will increase and it will be advantageous for thinning, so not only will the overall thickness of sanitary products be thinner, but performance improvements such as breathability can be expected. . However, in order for superabsorbent resin fibers to replace pulp, they must exhibit sufficient permeability so that the solution can be sufficiently absorbed to the lower part of sanitary products, but currently developed superabsorbent resin fibers have the problem of poor permeability.

Republic of Korea Public Patent No. 2017-0110947

Accordingly, in order to solve the problems of the prior art as described above, the present invention seeks to provide a polymer-coated superabsorbent resin fiber with improved liquid permeability without deteriorating absorbent properties such as water retention capacity and absorbency under pressure, and a method for manufacturing the same.

In order to achieve the above object, one aspect of the present invention is,

Preparing a spinning solution by mixing a polymer solution containing an acrylic acid-based polymer and at least some of the acidic groups of the acrylic acid-based polymer have been neutralized with a crosslinking agent;

manufacturing a superabsorbent polymer fiber by spinning the spinning solution through a solution blown process and performing primary heat treatment;

Coating a polymer solution containing polyvinylpyrrolidone (PVP) on the superabsorbent polymer fiber; and

Performing secondary heat treatment on the superabsorbent polymer fiber coated with the polymer solution;

It provides a method for producing a polymer-coated superabsorbent resin fiber, including a.

In addition, another aspect of the present invention is,

An acrylic acid-based polymer in which at least a portion of the acidic groups are neutralized, and a superabsorbent resin fiber cross-polymerized with a cross-linking agent; and

It is formed on the surface of the superabsorbent polymer fiber and includes a surface crosslinking layer derived from polyvinylpyrrolidone (PVP),

Provides polymer-coated superabsorbent resin fiber.

The polymer-coated superabsorbent resin fiber manufactured according to the present invention has absorbency, and unlike conventional superabsorbent resins in the form of powder or particles, there is no risk of scattering or leaking into the product in the form of fiber, and it can exhibit improved liquid permeability. .

The polymer-coated superabsorbent resin fiber according to the present invention can be used alone or mixed with conventional superabsorbent resin powder as a substitute for fluff pulp, and can be used as a superabsorbent resin particle core in sanitary materials such as diapers and sanitary napkins. It can be applied to various fields such as liquid-permeable encapsulant that surrounds the core, waterproofing material applied to walls, roofs, cables, etc., oil filter for moisture removal, dressing for wounds and blemishes, food packaging material to prevent moisture leaching, and sweat absorbent material for fire protection clothing. You can.

Figure 1 is a schematic diagram showing the manufacturing process of superabsorbent polymer fiber according to an embodiment of the present invention.

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

Hereinafter, a polymer-coated superabsorbent resin fiber and a method for manufacturing the same according to an embodiment of the present invention will be described.

The polymer-coated superabsorbent resin fiber according to one embodiment of the present invention includes an acrylic acid-based polymer in which at least a portion of the acidic group is neutralized, and a superabsorbent resin fiber in which a crosslinking agent is crosslinked and polymerized; and a surface crosslinking layer formed on the surface of the superabsorbent polymer fiber and derived from polyvinylpyrrolidone (PVP).

The polymer-coated superabsorbent resin fiber of the present invention is in the form of short fibers, and its aggregate is in the form of pulp or cotton, and can itself exhibit absorbency and liquid permeability for liquid.

Preferably, the polymer-coated superabsorbent resin fiber of the present invention can be used in absorbent articles such as diapers containing a superabsorbent polymer, and in such absorbent articles, the superabsorbent resin powder, particles, or third form. It can be used as a substitute for conventional pulp by mixing with superabsorbent resin. Therefore, the polymer-coated superabsorbent resin fiber of the present invention can be used in products as a replacement for fluff pulp used as a filler.

Accordingly, the absorbent article containing the polymer-coated superabsorbent resin fiber according to the present invention does not use pulp such as conventional cellulose-based or polyester-based fibers, or the amount used can be significantly reduced, so it has a water retention capacity or absorbency under pressure. It is possible to exhibit improved liquid permeability without deteriorating the absorption properties such as.

Additionally, the polymer-coated superabsorbent resin fiber can exhibit excellent absorbency and liquid permeability.

For example, the polymer-coated superabsorbent polymer fiber has a centrifugation retention capacity (CRC) measured according to the EDANA method WSP 241.2 of about 10 g/g or more, or about 11 g/g or more, and about 20 g/g/g/g. g/g or less, or about 18 g/g or less, or about 15 g/g or less.

In addition, the polymer-coated superabsorbent resin fiber has an absorbency under pressure (AUL) of 0.9 psi measured according to the method of EDANA method WSP 242.2 of about 10 g/g or more, or about 11 g/g or more, or about 12 g/g. or more, but may range from about 25 g/g or less, or about 20 g/g or less, or about 18 g/g or less.

In addition, the polymer-coated superabsorbent resin fiber has a saline flow conductivity (SFC) value of about 80 * 10 ^-7 cm ³ ·sec/g or more, or about 90 * 10 ^-7 cm ³ ·sec/g or more, or About 100*10 ^-7 cm ³ ·sec/g or more, but about 150*10 ^-7 cm ³ ·sec/g or less, or about 140*10 ^-7 cm ³ ·sec/g or less, or about 130*10 ^- It may have a range of ⁷ cm ³ ·sec/g or less.

The polymer-coated superabsorbent resin fiber according to the present invention is suitable for use in various articles requiring hygroscopicity, including diapers and sanitary materials, either alone or mixed without limitation with other highly absorbent resins, particles, powders, or other components. It can be used effectively.

The uses of the polymer-coated superabsorbent resin fiber according to the present invention are not particularly limited, and include sanitary products, liquid-permeable encapsulants, waterproofing materials, filters for removing moisture, dressing agents, food packaging materials to prevent moisture leaching, sweat absorbents, etc. in medicine, chemistry, etc. , can encompass all products used in various fields such as chemical engineering, foodstuffs, or cosmetics.

The polymer-coated superabsorbent resin fiber according to one embodiment of the present invention includes an acrylic acid-based polymer in which at least a portion of acidic groups are neutralized, and a superabsorbent resin fiber in which a crosslinking agent is crosslinked and polymerized; and a surface crosslinking layer formed on the surface of the superabsorbent polymer fiber and derived from polyvinylpyrrolidone (PVP).

The acrylic acid-based polymer is a polymer obtained by polymerizing an acrylic acid-based monomer represented by the following formula (1):

[Formula 1]

R ¹ -COOM ¹

In Formula 1,

R ¹ is an alkyl group having 2 to 5 carbon atoms containing an unsaturated bond,

M ¹ is a hydrogen atom, a monovalent or divalent metal, an ammonium group, or an organic amine salt.

Preferably, the acrylic acid-based monomer may include at least one selected from the group consisting of acrylic acid, methacrylic acid, and monovalent metal salts, divalent metal salts, ammonium salts, and organic amine salts thereof.

At this time, the polymer may refer to both a polymer obtained by homopolymerizing the acrylic acid-based monomer or a copolymer obtained by polymerizing the acrylic acid-based monomer and a comonomer according to a common method in the technical field to which the present invention pertains.

According to one embodiment of the present invention, the acrylic acid-based monomer or the polymer of the acrylic acid-based monomer may have an acidic group and at least a portion of the acidic group may be neutralized. Preferably, the acrylic acid-based monomer or the polymer of the acrylic acid-based monomer partially neutralized with an alkaline substance such as sodium hydroxide, potassium hydroxide, ammonium hydroxide, etc. may be used. At this time, the degree of neutralization of the polymer may be about 40 to about 95 mol%, or about 40 to about 80 mol%, or about 45 to about 70 mol%. If the degree of neutralization is too high, there are few sites where hydrogen bonds can form, so a sufficient surface cross-linking layer may not be formed on the surface of the polymer. Conversely, if the degree of neutralization is too low, the absorption power of the polymer will be greatly reduced and handling It can exhibit properties similar to elastic rubber, which are difficult to achieve.

In the polymer-coated superabsorbent resin fiber according to the present invention, the cross-linked polymer refers to a cross-polymerization of the polymer of the acrylic acid-based monomer and the cross-linking agent described above.

As the crosslinking agent, a crosslinking agent having two or more functional groups capable of reacting with water-soluble substituents present in the acrylic acid-based monomer or the polymer of the acrylic acid-based monomer may be used.

More specifically, it is preferable to use a crosslinking agent having two or more epoxy groups or hydroxy groups in order to achieve the absorption properties of the superabsorbent polymer fiber.

Specific examples of such crosslinking agents include ethylene glycol, glycerol, polyvinyl alcohol, polyglycidyl acrylate, polyglycidyl methacrylate, poly(ethylene glycol) diglycidyl ether, polyethylene glycol, One or more selected from the group consisting of polypropylene glycol, poly(4-hydroxybutyl acrylate), poly(2-hydroxyethyl acrylate), and poly(2-hydroxypropyl acrylate) may be used.

The polymer-coated superabsorbent resin fiber of the present invention further includes a surface cross-linked layer on the surface of the cross-polymerized superabsorbent resin fiber, and the surface cross-linked layer is characterized in that it is derived from polyvinylpyrrolidone (PVP). .

That is, the surface cross-linked layer is formed by hydrogen bonding between the hydrogen of the carboxylic acid group of the acrylic acid polymer and the oxygen atom of the carbonyl group in polyvinylpyrrolidone, and is in the form of a film surrounding the surface of the superabsorbent polymer fiber. As the surface gel strength of the superabsorbent polymer fiber increases due to the surface cross-linking layer, the effect of improving liquid permeability can be shown.

Most sanitary materials contain highly absorbent particles and cellulose-based or polyester-based fibers called pulp. This pulp, which accounts for 30 to 50% of the total weight of sanitary materials, has no or very low absorption of liquid.

Accordingly, if a superabsorbent polymer in the form of an absorbent fiber is used as a substitute for pulp, not only can the overall thickness of sanitary products be thinned, but the physical properties of sanitary materials such as absorbency and liquid permeability can also be improved overall. To achieve this, the superabsorbent polymer fiber must not only have absorbency but also exhibit a sufficient level of permeability so that the absorbed solution can be sufficiently absorbed to the lower part of the sanitary product.

The inventors of the present invention conducted repeated research on this and formed a surface cross-linking layer on the surface of superabsorbent resin fibers, which are cross-linked polymers in the form of fibers, using polyvinylpyrrolidone as a surface cross-linking agent, thereby improving liquid permeability without lowering absorbency. The present invention was developed by focusing on the possibility of providing a polymer-coated superabsorbent resin fiber that represents.

Existing superabsorbent polymers are in the form of particles, and when surface crosslinking them, a method is used in which the surface crosslinking agent penetrates the surface of the particles, which usually have a diameter of 200 to 1000 ㎛, to a depth of 5 to 100 ㎛. However, in the case of fiber-type superabsorbent polymer, the fiber diameter is around 20 to 100㎛, which is much smaller than the diameter of particle-type superabsorbent polymer. Therefore, if the surface cross-linking method is applied to superabsorbent polymer particles, cross-linking occurs even inside the superabsorbent polymer fiber. A reaction occurs. Therefore, it is difficult to implement an appropriate surface cross-linked layer structure with different internal and external cross-linking densities, and as a result, the effect of improving liquid permeability is not achieved.

Accordingly, according to the present invention, polyvinylpyrrolidone, a hydrophilic polymer, is used so that the surface crosslinking agent can occur only on the surface without penetrating into the interior of the fiber during the surface crosslinking reaction of the superabsorbent polymer fiber.

The carbonyl group (-CO- group) of polyvinylpyrrolidone forms a strong hydrogen bond with the unionized carboxylic acid group (-COOH group) of the superabsorbent resin fiber, forming a coating layer that is insoluble in water. When a covalent bond is formed between polyvinylpyrrolidone and the superabsorbent polymer fiber through heat treatment on the superabsorbent polymer fiber with such a coating layer formed, a surface crosslinked layer is formed only on the surface of the superabsorbent polymer fiber, and thus the surface crosslinked layer becomes superabsorbent. The crosslinking density becomes higher than that inside the resin fiber. The surface cross-linked layer with increased cross-link density has a small water absorption capacity, so it can have a relatively high gel strength in the swollen state. As a result, polymer-coated superabsorbent resin fibers with improved liquid permeability can be obtained while maintaining the water retention capacity and absorbency under pressure of the superabsorbent polymer.

According to one embodiment of the present invention, the weight average molecular weight (Mw) of polyvinylpyrrolidone is 5,000 g/mol or more, or 10,000 g/mol or more, and 100,000 g/mol or less, or 80,000 g/mol or less, or It may be less than 60,000 g/mol.

If the weight average molecular weight of the polyvinylpyrrolidone is lower than 5,000 g/mol, it may penetrate into the interior of the superabsorbent polymer fiber and internal crosslinking may occur, resulting in a significant decrease in water retention capacity. Conversely, if the weight average molecular weight of polyvinylpyrrolidone is higher than 100,000 g/mol, uniform surface coating may be difficult due to low solubility and diffusivity in the solvent of the polymer solution. Therefore, from this point of view, the weight average molecular weight of polyvinylpyrrolidone is preferably 5,000 to 100,000 g/mol, and more preferably 10,000 to 60,000 g/mol.

Accordingly, according to another embodiment of the present invention, a sanitary material containing the above-described polymer-coated superabsorbent resin fiber is provided.

A method for producing a polymer-coated superabsorbent resin fiber according to another embodiment of the present invention includes mixing an acrylic acid-based polymer and a polymer solution in which at least some of the acidic groups of the acrylic acid-based polymer have been neutralized with a crosslinking agent to prepare a spinning solution. manufacturing step; manufacturing a superabsorbent polymer fiber by spinning the spinning solution through a solution blown process and performing primary heat treatment; Coating a polymer solution containing polyvinylpyrrolidone (PVP) on the superabsorbent polymer fiber; and performing secondary heat treatment on the superabsorbent resin fiber coated with the polymer solution.

In the method for producing a superabsorbent polymer fiber according to an embodiment of the present invention, first, a spinning solution is prepared by mixing a polymer solution containing an acrylic acid-based polymer and at least some of the acidic groups of the acrylic acid-based polymer have been neutralized with a crosslinking agent. do.

The polymer may be a polymer obtained by homopolymerizing an acrylic acid-based monomer in which at least a portion of the acidic group has been neutralized, or a copolymer obtained by polymerizing the acrylic acid-based monomer and a comonomer, according to a common method in the technical field to which the present invention pertains.

The acrylic acid-based monomer is a compound represented by the following formula (1):

[Formula 1]

R ¹ -COOM ¹

In Formula 1,

R ¹ is an alkyl group having 2 to 5 carbon atoms containing an unsaturated bond,

M ¹ is a hydrogen atom, a monovalent or divalent metal, an ammonium group, or an organic amine salt.

Preferably, the acrylic acid-based monomer may include at least one selected from the group consisting of acrylic acid, methacrylic acid, and monovalent metal salts, divalent metal salts, ammonium salts, and organic amine salts thereof.

According to one embodiment of the present invention, the polymer solution includes preparing an acrylic acid-based polymer by polymerizing acrylic acid-based monomers; and mixing an alkaline substance with the acrylic acid-based polymer to neutralize at least some of the acidic groups of the acrylic acid-based polymer.

According to another embodiment of the present invention, the polymer solution first neutralizes at least some of the acidic groups of the acrylic acid-based monomer by mixing an alkaline substance with the acrylic acid-based monomer, and then polymerizes the acrylic acid-based monomer in which some of the acidic groups have been neutralized. Thus, an acrylic acid-based polymer can also be produced.

As an alkaline substance that neutralizes the acrylic acid-based monomer or the polymer of the acrylic acid-based monomer, for example, sodium hydroxide, potassium hydroxide, ammonium hydroxide, etc. can be used.

At this time, the degree of neutralization of the acrylic acid-based monomer or polymer may be about 40 to about 90 mol%, or about 40 to about 80 mol%, or about 45 to about 70 mol%. If the degree of neutralization is too high, it may be difficult to create sufficient hydrogen bonds in the surface cross-linking step that proceeds later, so the surface cross-linking layer may not be sufficiently formed. Conversely, if the degree of neutralization is too low, the absorbent power of the superabsorbent polymer will be greatly reduced and it will be difficult to handle. It can exhibit difficult elastic rubber-like properties.

In the method for producing polymer-coated superabsorbent resin fibers according to the present invention, the spinning solution includes a crosslinking agent. The cross-linking agent included in the spinning solution may serve as an internal cross-linking agent that cross-links the interior of the superabsorbent polymer.

More specifically, it is preferable to use a crosslinking agent having two or more epoxy groups or hydroxy groups in order to achieve the absorption properties of the superabsorbent polymer fiber. Specific examples of such crosslinking agents include ethylene glycol, glycerol, polyvinyl alcohol, polyglycidyl acrylate, polyglycidyl methacrylate, poly(ethylene glycol) diglycidyl ether, polyethylene glycol, One or more selected from the group consisting of polypropylene glycol, poly(4-hydroxybutyl acrylate), poly(2-hydroxyethyl acrylate), and poly(2-hydroxypropyl acrylate) may be used.

The crosslinking agent may be included in a concentration of about 0.01 to about 2 parts by weight, or 0.1 to 0.5 parts by weight based on 100 parts by weight of the polymer solution, to crosslink the polymer.

In the production method of the present invention, the polymer solution may further include additives such as a thickener, a plasticizer, a storage stabilizer, and an antioxidant, if necessary.

Next, the prepared spinning solution is spun through a solution blown process and primary heat treatment is performed to produce superabsorbent polymer fibers.

Methods for manufacturing polymers in the form of fibers include melt-blown spinning, jet spinning, centrifugal spinning, and electro-spinning.

In centrifugal spinning, polymers in a molten or solution state are put into a spinneret with a large number of holes and rotated at high speed. The centrifugal force acting at this time is used to stretch the unsolidified polymers, fines them, and laminate the solidified fibers on a collector to create a non-woven fabric. This is a method of manufacturing. The advantages of centrifugal spinning include simple equipment configuration, low energy consumption, limited polymers that can be used, and the simplification of the process because it is manufactured in the form of non-woven fabric.

However, centrifugal spinning is difficult to mass produce, has low productivity, is not suitable for producing long fibers, and cannot produce fibers with a diameter of 10 μm or more. As a result, there are problems such as reduced absorption speed and liquid permeability, so there are ways to improve these problems. In the present invention, it is preferable to form superabsorbent resin fibers by a solution blown process.

In the solution blown process, a spinning solution containing a polymer is spun in the form of a thin stream through a micro channel, and drying and internal crosslinking processes are simultaneously performed on the spun polymer solution to continuously form flexible superabsorbent polymer fibers. It is a process that can be produced.

1 is a schematic diagram showing a manufacturing process according to an embodiment of the present invention.

Referring to Figure 1, the prepared polymer solution is spun on a movable conveyor belt, etc., and can be spun continuously through a micro channel or nozzle with a width of 1000 ㎛ or less. Additionally, a more uniform stream can be formed by flowing a gas such as air or inert gas around the spun polymer solution stream.

A superabsorbent polymer in the form of fiber can be manufactured by this solution blown process. At this time, a process of drying the solvent contained in the spinning solution may be performed simultaneously with the spinning process on the spun polymer solution using hot air supply, infrared irradiation, microwave irradiation, or ultraviolet irradiation.

A superabsorbent polymer fiber is manufactured by performing primary heat treatment after the spinning process or simultaneously with the spinning process.

In the first heat treatment step, the solvent contained in the spinning solution is dried by an elevated temperature, and at the same time, the spun polymer and the crosslinking agent undergo a crosslinking reaction, thereby producing a superabsorbent polymer that is a crosslinked polymer in the form of a fiber.

The first heat treatment step may be performed at a temperature of 160 to 220°C, or 180 to 200°C. If the heat treatment temperature is less than 180°C, there is a risk that the heat treatment time will be too long and the crosslinking reaction will not sufficiently occur, and if the heat treatment temperature is higher than 220°C, there is a risk that the absorption properties of the final formed superabsorbent polymer fiber may decrease. .

In addition, in the case of the first heat treatment time, there is no limitation in its composition, but considering process efficiency, etc., it may be performed for 10 minutes to 180 minutes, more preferably 20 minutes to 120 minutes.

As long as it is commonly used as a means of the first heat treatment step, it can be selected and used without limitation in its composition. Specifically, the first heat treatment step can be performed by methods such as hot air supply, infrared irradiation, microwave irradiation, or ultraviolet ray irradiation.

According to one embodiment of the present invention, the moisture generated during the first heat treatment process can be continuously suctioned for more effective drying.

Meanwhile, in the production of a conventional superabsorbent polymer in powder form, a water-containing gel polymer with a water content of about 40 to about 80% by weight is usually obtained through polymerization of an aqueous monomer solution, and this water-containing gel polymer is dried and pulverized to produce a powder-type superabsorbent polymer. get resin.

However, according to one embodiment of the present invention, internal crosslinking and drying processes are performed simultaneously by performing a first heat treatment step on the spun polymer solution, thereby allowing the crosslinked polymer to be obtained in the form of a fiber. The moisture content of the superabsorbent polymer fiber obtained by performing the crosslinking and drying process as described above may be 2 to 6% by weight.

Next, a polymer solution containing polyvinylpyrrolidone is coated on the superabsorbent polymer fiber that has undergone the first heat treatment, and then a secondary heat treatment is performed on the superabsorbent resin fiber coated with the polymer solution.

As described above, a polymer solution containing polyvinylpyrrolidone is coated on the superabsorbent polymer fiber, and then a secondary heat treatment is performed on the superabsorbent polymer fiber coated with the polymer solution, thereby forming the superabsorbent polymer fiber and the polyvinylpyrrolidone. A surface crosslinking reaction with vinylpyrrolidone may occur, forming a surface crosslinking layer derived from polyvinylpyrrolidone on the surface of the superabsorbent polymer fiber.

The surface cross-linking reaction is a step of forming super-absorbent resin fibers with improved physical properties by inducing a cross-linking reaction on the surface of the super-absorbent resin fibers in the presence of a polymer solution containing polyvinylpyrrolidone. Through this surface cross-linking reaction, a surface cross-linking layer is formed on the surface of the superabsorbent polymer fiber.

According to one embodiment of the present invention, preferably in order to improve the properties of the resulting superabsorbent polymer fiber, the weight average molecular weight (Mw) is 5,000 g/mol or more, or 1,000 g/mol or more, or 10,000 g/mol. or more, but less than 100,000 g/mol, or less than 80,000 g/mol, or less than 60,000 g/mol of polyvinylpyrrolidone can be used.

If the weight average molecular weight of the polyvinylpyrrolidone is lower than 5,000 g/mol, it may penetrate into the interior of the superabsorbent polymer fiber and internal crosslinking may occur, resulting in a significant decrease in water retention capacity. Conversely, if the weight average molecular weight of polyvinylpyrrolidone is higher than 100,000 g/mol, uniform surface coating may be difficult due to low solubility and diffusivity in the solvent of the polymer solution. Therefore, from this point of view, the weight average molecular weight of polyvinylpyrrolidone is preferably 5,000 to 100,000 g/mol, and more preferably 10,000 to 60,000 g/mol.

The solvent for the polyvinylpyrrolidone solution added may be a hydrophilic alcohol such as anhydrous ethanol, methanol, isopropyl alcohol, or ketone. At this time, the concentration of polyvinylpyrrolidone in the solvent is 0.1 to 1% by weight, or 0.1 to 0.5% by weight for the purpose of inducing even dispersion of polyvinylpyrrolidone and optimizing the surface penetration depth for the polymer. It can be done as much as possible. If the content of polyvinylpyrrolidone is too small, surface cross-linking reaction hardly occurs, and if it is included in too much, the absorption capacity and physical properties may decrease due to excessive surface cross-linking reaction.

There is no limitation on the method of coating the polymer solution on the superabsorbent polymer fiber. Methods such as mixing the polymer solution and the superabsorbent resin fibers in a reaction tank, spraying the polymer solution on the superabsorbent polymer fibers, or immersing the superabsorbent resin fibers in the polymer solution can be used. Polyvinyl for the polymer For even dispersion of pyrrolidone, a method of immersing superabsorbent resin fibers in the polymer solution may be preferably used.

Meanwhile, the mixing ratio of the polymer solution and the superabsorbent polymer fibers is not particularly limited. For example, 1 to 10 g of superabsorbent polymer fibers are immersed per 1 L of the polymer solution so that polyvinylpyrrolidone can sufficiently penetrate the superabsorbent polymer fibers. It can be coated.

According to one embodiment of the present invention, the polymer solution may be coated in several layers on the superabsorbent polymer fiber to increase the effect of improving liquid permeability. For example, after mixing a polymer solution with a superabsorbent polymer fiber to form a coating layer, applying the non-neutralized polymer solution again, and further coating the polymer solution on top, the process is repeated to form a multi-layer coating layer. may form.

When a multi-layer coating layer is formed in this way, the liquid permeability of the superabsorbent polymer fiber can be further improved.

The secondary heat treatment step may be performed at a temperature of 160 to 220°C, or 180 to 200°C. If the heat treatment temperature is less than 180℃, there is a risk that the heat treatment time will be too long and the surface crosslinking reaction will not sufficiently occur, and if the heat treatment temperature is higher than 220℃, side reactions may occur or the superabsorbent polymer will deteriorate, resulting in the final formed superabsorbent. There is a risk that the physical properties of the resin fiber may actually deteriorate.

According to the secondary heat treatment process as described above, polyvinylpyrrolidone chemically bonds with the functional groups on the surface of the superabsorbent polymer fiber to form a surface cross-linked layer, which is a uniform and strong insoluble film.

As long as it is commonly used as a means of the secondary heat treatment step, it can be selected and used without limitation in its composition. Specifically, the secondary heat treatment step can be performed by methods such as hot air supply, infrared irradiation, microwave irradiation, or ultraviolet ray irradiation.

Obtained according to the above manufacturing method polymer coating As described above, superabsorbent polymer fibers can exhibit improved liquid permeability without lowering absorbency.

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.

<Example>

Example 1

A polymer solution with a solid content of 32% and a degree of neutralization of 70% was prepared by mixing 400 parts by weight of poly(acrylic acid), 54.4 parts by weight of sodium hydroxide (NaOH), and 37.5 parts by weight of water. A spinning solution was prepared by mixing 1.45 parts by weight of ethylene glycol as a crosslinking agent.

The prepared spinning solution was spun through the solution blown process as shown in Figure 1, cross-linked and dried at 190°C for 120 minutes to obtain an aggregate of superabsorbent resin fibers in the form of a non-woven fabric.

The obtained superabsorbent polymer fiber aggregate was coated by immersing it in a 0.5% by weight polyvinylpyrrolidone (weight average molecular weight: 10,000 g/mol) solution (dissolved in absolute ethanol) at 60°C for 30 minutes.

Afterwards, the aggregate of superabsorbent polymer fibers was separated from the polyvinylpyrrolidone solution, the solvent was dried at 90°C, and heat treatment was performed at 190°C for 90 minutes to form a continuous surface cross-linked layer on the surface of the superabsorbent polymer fibers.

Example 2

In Example 1, a superabsorbent polymer fiber was prepared in the same manner as Example 1, except that polyvinylpyrrolidone with a weight average molecular weight of 58,000 g/mol was used.

Example 3

In the same manner as in Example 1, except for the process of coating the polyvinylpyrrolidone solution in Example 1, applying a non-neutralized polyacrylic acid polymer solution, and then additionally coating the same polyvinylpyrrolidone solution again. A superabsorbent resin fiber was prepared.

Comparative Example 1

In Example 1, the state of the superabsorbent polymer fiber before coating with a polyvinylpyrrolidone solution was used as Comparative Example 1.

Comparative Example 2

In Example 1, a superabsorbent polymer fiber was prepared in the same manner as Example 1, except that ethylene glycol (weight average molecular weight: 62 g/mol) was used instead of polyvinylpyrrolidone.

<Experimental example>

(1) Centrifuge Retention Capacity (CRC)

The centrifugation retention capacity (CRC) of the superabsorbent polymer fibers prepared in Examples and Comparative Examples was determined by EDANA method WSP 241.2, except that fiber-type superabsorbent polymer was used as the measurement sample instead of particle-type superabsorbent polymer. It was measured according to the method.

Specifically, superabsorbent resin fibers W ₀ (g, about 0.2 g) were uniformly placed in a non-woven bag and sealed. Then, the bag was immersed in 0.9% by weight physiological saline solution at room temperature. After 30 minutes, the bag was dehydrated at 250G for 3 minutes using a centrifuge, and then the weight W ₂ (g) of the bag was measured. Meanwhile, the same operation was performed using an empty bag without superabsorbent polymer, and then the weight W ₁ (g) was measured.

Using each weight obtained in this way, the centrifugation retention capacity was confirmed using the following calculation formula 1.

[Calculation Formula 1]

CRC(g/g) = {[W ₂ (g) - W ₁ (g)]/W ₀ (g)} - 1

In equation 1 above,

W ₀ (g) is the initial weight (g) of the superabsorbent polymer fiber,

W ₁ (g) is the weight of the device measured after dehydration at 250G for 3 minutes using a centrifuge without using superabsorbent polymer fiber,

W ₂ (g) is measured including the superabsorbent polymer fibers by immersing them in 0.9% by weight of physiological saline solution at room temperature for 30 minutes and then dehydrating them at 250G for 3 minutes using a centrifuge. It is one device weight.

(2) Absorbency under Load (AUL)

The absorbency under load (AUL) of 0.9 psi for the superabsorbent polymer fibers prepared in Examples and Comparative Examples was measured using EDANA method WSP 242.2, except that fiber-type superabsorbent polymer was used as the measurement sample instead of particle-type superabsorbent polymer. It was measured according to the method.

Specifically, a stainless steel 400 mesh screen was installed at the bottom of a plastic cylinder with an inner diameter of 25 mm. Then, superabsorbent polymer fiber W ₀ (g, about 0.16 g) whose absorbency under pressure is to be measured was uniformly sprayed on the screen at room temperature and 50% humidity. Next, a piston capable of uniformly applying a load of 0.9 psi was added on the superabsorbent polymer. At this time, a piston was used that had an outer diameter slightly smaller than 25 mm, had no gap with the inner wall of the cylinder, and was manufactured to move freely up and down. Then, the weight W ₃ (g) of the device prepared in this way was measured.

Next, a glass filter with a diameter of 90 mm and a thickness of 5 mm was placed inside a 150 mm diameter Petro dish, and 0.9 wt% physiological saline solution was poured into the Petro dish. At this time, saline solution was poured until the water surface of the saline solution was level with the upper surface of the glass filter. Then, a sheet of filter paper with a diameter of 90 mm was placed on the glass filter.

Next, the prepared device was placed on the filter paper so that the superabsorbent polymer in the device was swollen by physiological saline solution under load. After 1 hour, the weight W ₄ (g) of the device containing the swollen superabsorbent polymer was measured.

Using the weight measured in this way, the pressure absorption capacity was calculated according to the following equation 2.

[Calculation Formula 2]

AUL(g/g) = [W ₄ (g) - W ₃ (g)]/ W ₀ (g)

In equation 2 above,

W ₀ (g) is the initial weight (g) of the superabsorbent polymer fiber,

W ₃ (g) is the total weight of the superabsorbent polymer fiber and the weight of the device capable of applying a load to the superabsorbent polymer fiber,

W ₄ (g) is the weight of the superabsorbent polymer fiber and the weight of the device capable of applying a load to the superabsorbent polymer fiber after absorbing physiological saline solution into the superabsorbent polymer fiber for 1 hour under a load (0.9 psi). It's the total.

(3) Saline flow conductivity (SFC)

It was measured and calculated according to the method disclosed in columns 54 to 59 of U.S. Patent Registration No. 5562646.

The properties of the polymer-coated superabsorbent resin fibers prepared in Examples and Comparative Examples were evaluated in the following manner and are shown in Table 1 below.

CRC
(g/g) 0.9 AUL
(g/g) S.F.C.
(*10 ^-7 cm ³ ·sec/g) Example 1 11.9 12.7 125 Example 2 12.4 13.2 97 Example 3 12 12.3 131 Comparative Example 1 13.7 13 76 Comparative Example 2 6.2 9.9 119

Referring to Table 1, the superabsorbent resin fiber whose surface coating layer was formed using polyvinylpyrrolidone according to the manufacturing method of the present invention has excellent centrifuge retention capacity (CRC), absorbency under pressure (AUL) of 0.9 psi, and physiological saline solution. Flow conductivity (SFC) is shown.

On the other hand, Comparative Example 1, in which the polyvinylpyrrolidone cross-linked layer was not formed, had poor liquid permeability measured by saline flow conductivity (SFC), and Comparative Example 1 in which the surface coating layer was formed with ethylene glycol rather than polyvinylpyrrolidone 2 had relatively good liquid permeability, but did not show satisfactory absorption properties due to poor centrifugation retention capacity and low pressure absorption capacity. This can be seen as because the weight average molecular weight of ethylene glycol is too low, so that ethylene glycol penetrates into the interior of the superabsorbent polymer fiber, and as internal crosslinking progresses, water retention capacity decreases.

Claims (17)

Preparing a spinning solution by mixing a polymer solution containing an acrylic acid-based polymer and at least some of the acidic groups of the acrylic acid-based polymer have been neutralized with a crosslinking agent;
manufacturing a superabsorbent polymer fiber by spinning the spinning solution through a solution blown process and performing primary heat treatment;
Coating a polymer solution containing polyvinylpyrrolidone (PVP) on the superabsorbent polymer fiber;
Coating an acrylic acid-based polymer solution in which acidic groups are not neutralized;
Additional coating with a polymer solution; and
Performing secondary heat treatment on the superabsorbent polymer fiber coated with the polymer solution;
A method for producing a polymer-coated superabsorbent resin fiber comprising,
The polymer-coated superabsorbent resin fiber has a physiological saline flow conductivity (SFC) value of 100*10 -7 to 100*10 ^-7 . 150*10 ^-7 cm ³ ·sec/g phosphorus,
Method for producing polymer-coated superabsorbent resin fiber.
delete According to paragraph 1,
A method for producing a polymer-coated superabsorbent resin fiber, wherein the first and second heat treatments are performed at a temperature of 160 to 220°C.
According to paragraph 1,
The crosslinking agent is ethylene glycol, glycerol, polyvinyl alcohol, polyglycidyl acrylate, polyglycidyl methacrylate, poly(ethylene glycol) diglycidyl ether, polyethylene glycol, and polypropylene. A polymer coating polymer comprising at least one member selected from the group consisting of glycol, poly(4-hydroxybutyl acrylate), poly(2-hydroxyethyl acrylate), and poly(2-hydroxypropyl acrylate). Method for producing absorbent resin fiber.
According to paragraph 1,
The polymer solution includes a solvent selected from the group consisting of anhydrous ethanol, methanol, isopropyl alcohol, and ketone.
According to paragraph 1,
A method for producing a polymer-coated superabsorbent resin fiber, wherein the weight average molecular weight (Mw) of polyvinylpyrrolidone is 5,000 to 100,000 g/mol.
According to paragraph 1,
A method of producing a polymer-coated superabsorbent resin fiber, wherein the degree of neutralization of the acrylic acid-based polymer is 40 to 95 mol%.
According to paragraph 1,
The polymer solution is,
Preparing an acrylic acid-based polymer by polymerizing acrylic acid-based monomers; and mixing an alkaline substance into the acrylic acid-based polymer to neutralize at least some of the acidic groups of the acrylic acid-based polymer.
According to clause 8,
The acrylic acid-based monomer is represented by the following formula (1): Method for producing a polymer-coated superabsorbent resin fiber:
[Formula 1]
R ¹ -COOM ^1`
In Formula 1,
R ¹ is an alkyl group having 2 to 5 carbon atoms containing an unsaturated bond,
M ¹ is a hydrogen atom, a monovalent or divalent metal, an ammonium group, or an organic amine salt.
An acrylic acid-based polymer in which at least a portion of the acidic groups are neutralized, and a superabsorbent resin fiber cross-polymerized with a cross-linking agent; and
It is formed on the surface of the superabsorbent polymer fiber and includes a surface crosslinking layer derived from polyvinylpyrrolidone (PVP),
Physiological saline flow conductivity (SFC) value is 100*10 ^-7 to 150*10 ^-7 cm ³ ·sec/g phosphorus,
Polymer coated super absorbent resin fiber.
According to clause 10,
The neutralization degree of the acrylic acid-based polymer is 40 to 95 mol%, a polymer-coated superabsorbent resin fiber.
According to clause 10,
The crosslinking agent is ethylene glycol, glycerol, polyvinyl alcohol, polyglycidyl acrylate, polyglycidyl methacrylate, poly(ethylene glycol) diglycidyl ether, polyethylene glycol, and polypropylene. A polymer coating polymer comprising at least one member selected from the group consisting of glycol, poly(4-hydroxybutyl acrylate), poly(2-hydroxyethyl acrylate), and poly(2-hydroxypropyl acrylate). Absorbent resin fiber.
According to clause 10,
Polyvinylpyrrolidone has a weight average molecular weight (Mw) of 5,000 to 100,000 g/mol, a polymer-coated superabsorbent resin fiber.
According to clause 10,
The polymer-coated superabsorbent resin fiber has a centrifugal retention capacity (CRC) of 10 to 20 g/g, measured according to the EDANA method WSP 241.2.
According to clause 10,
The polymer-coated superabsorbent resin fiber has an absorbency under load (AUL) of 10 to 25 g/g at 0.9 psi, measured according to the method of EDANA WSP 242.2.
delete A sanitary material comprising the polymer-coated superabsorbent resin fiber of any one of claims 10 to 15.