KR102589558B1 - Manufacturing Method of Super Absorbent Substrate - Google Patents

Abstract

The present invention includes the steps of irradiating radiation to a substrate containing a nitrile group-containing polymer; and mixing the irradiated substrate with a solvent and a strong base, wherein the solvent includes water and an organic solvent.

Description

Manufacturing Method of Super Absorbent Substrate}

The present invention relates to a method for producing a highly absorbent substrate modified with a hydrophilic functional group, which can produce a highly absorbent substrate modified with a high yield.

Much research has been conducted for a long time on the manufacturing method of highly absorbent substrates such as superabsorbent fibers as media for storing fluids, and various application methods related thereto have also been proposed. For example, highly absorbent fibers are used in a wide range of fields such as paper diapers, sanitary products, mask packs, wound protection dressings, medical pads, gel-type air fresheners, agricultural and horticultural water retention agents, cosmetic products, construction anti-freeze materials, and cement and concrete admixtures. It is being used and applied.

In addition, due to the commercial success of disposable diapers using highly absorbent substrates, not only are new fields of highly absorbent substrates being studied, but substrates other than the existing powder form and superabsorbent substrates with specific shapes are being proposed.

As a method for producing highly absorbent substrates such as superabsorbent fibers, which have high utility and application potential in various fields, a method of polymerizing the absorbent single molecule or polymer by adding an initiator and a crosslinking agent was previously applied, which In addition to single molecules and polymers, there is a disadvantage that additional chemicals must be added and it is difficult to polymerize it into a uniform fiber shape.

As a method to solve the above problem, a method of introducing a hydrophilic functional group using radiation grafting technology has been developed. However, due to the nature of the grafting technology, this method requires increasing the content of the polymer having a functional group due to the content of the nonwoven fabric used as a raw material. There are limitations, the graft reaction process is very complicated, and there are many difficulties in controlling the graft yield, so there are still limitations in the production of highly absorbent substrates.

Accordingly, there is a need to develop an efficient manufacturing method that can produce highly absorbent substrates with high yield.

The present invention is intended to solve the above-mentioned problem, by crosslinking a substrate containing a nitrile group-containing polymer by irradiating radiation, and introducing a hydrophilic functional group to the surface of the substrate by controlling the polarity of the solvent mixed with the substrate, The aim is to provide a method for manufacturing a highly absorbent substrate that can be applied to various fields with high yield.

According to one embodiment of the present invention, irradiating radiation to a substrate containing a nitrile group-containing polymer; and mixing the irradiated substrate with a solvent and a strong base, wherein the solvent includes water and an organic solvent.

According to the manufacturing method of the superabsorbent substrate of the present invention, by varying the conditions of the solvent for radiation crosslinking and hydrophilization reaction, a highly absorbent substrate with excellent fluid absorption and dehumidification capacity can be manufactured with high yield even with a simple manufacturing process compared to the prior art. You can.

Figure 1 is a diagram showing the absorption amount over time for each transfer radiation dose of the superabsorbent fibers according to Examples 1 to 5.
Figure 2a is a diagram showing the yield of superabsorbent fibers according to Examples 6 to 16.
Figure 2b is a diagram showing the absorption amount of superabsorbent fibers according to Examples 6 to 16.
Figure 2c is a diagram showing the dehumidification rate of the superabsorbent fibers according to Examples 6 to 16.
Figure 3 is a diagram showing the absorption amount of superabsorbent fibers according to Examples 17 to 21.

Hereinafter, with reference to the attached drawings, the method for manufacturing the highly absorbent substrate of the present invention will be described in detail so that it can be easily performed by those skilled in the art.

Highly absorbent substrate refers to a substrate such as a fiber made of a highly absorbent polymer that can absorb moisture 500 to 1,000 times its own weight and does not release most of the water-based substances once absorbed. Specifically, the highly absorbent polymer fiber is a polymer that absorbs fluid by introducing a hydrophilic group in a single polymer chain structure or a three-dimensional network structure through cross-linking between polymer chains. The structure of the polymer in the substrate (structure of the fiber ) It refers to a cross-linked polymer that absorbs a large amount of liquid inside and expands to form a hydrogel, and can hold the absorbed liquid under a certain pressure.

A method for manufacturing a highly absorbent substrate according to an embodiment of the present invention includes irradiating radiation to a substrate containing a nitrile group-containing polymer; and mixing the irradiated substrate with a solvent and a strong base, wherein the solvent includes water and an organic solvent.

First, by irradiating radiation to a substrate containing a nitrile group-containing polymer, the substrate can be crosslinked. This can induce cross-linking by forming free radicals by cutting the weakly bonded portion of the substrate by irradiation energy.

The substrate containing the nitrile group-containing polymer may include polyacrylonitrile-based polymer and its derivatives. Here, the polyacrylonitrile-based polymer may include both homopolymers and copolymers. Specifically, the substrate containing the nitrile group-containing polymer is polyacrylonitrile (PAN), styrene-acrylonitrile copolymer (poly(styrene-co-acrylonitrile), SAN), and acrylonitrile-butadiene copolymer. (It may contain at least one selected from the group consisting of poly(acrylonitrile-co-butadiene, NBR) and acrylonitrile-butadiene-styrene terpolymer (poly(acrylonitrile-co-butadiene-co-styrene, ABS)) and may preferably contain polyacrylonitrile (PAN).

Since the nitrile group-containing polymer has a main chain made of carbon-carbon, it is chemically stable and has excellent mechanical properties. Therefore, the substrate containing the nitrile group-containing polymer is light, feels good, and has a high initial modulus of elasticity, so it can be used for clothing. and can have high utility for industrial purposes.

Additionally, the nitrile group contained in the polymer can be chemically modified in various ways through nucleophilic substitution reactions. As a specific example, a nitrile group can be converted to a carboxyl group (-COOH) by hydrolysis using an alkaline solution.

The substrate may be a fiber, fabric, or non-woven fabric.

The radiation may include at least one ionizing radiation selected from the group consisting of electron rays, alpha rays, beta rays, gamma rays, X-rays, and neutron rays. By irradiating the radiation, crosslinking occurs between polymer chains containing nitrile groups through chemical bonds, thereby allowing crosslinking of the substrate containing the polymer containing nitrile groups.

Additionally, the radiation may be administered at a dose of 50 to 500 kGy, preferably 100 to 400 kGy, and more preferably 250 to 350 kGy. When the radiation dose satisfies the above numerical range, the substrate containing a nitrile group-containing polymer can be sufficiently crosslinked while preventing the substrate from being decomposed due to excessive energy.

The radiation irradiation step may be performed at room temperature to prevent thermal deformation or decomposition of the substrate containing the nitrile group-containing polymer.

Next, mixing the irradiated substrate with a solvent and a strong base is performed.

The mixing step may include mixing the irradiated substrate with the solvent and then adding and mixing a strong base, or adding and mixing the irradiated substrate to the solvent to which the strong base has been added.

The solvent may include water and an organic solvent.

The solvent can greatly affect the reaction rate of functional group formation in the substrate containing the nitrile group-containing polymer by affecting reaction efficiency and side reaction generation.

The organic solvent may include at least one selected from the group consisting of alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.

The alcohol-based solvent may include a C ₁ to C ₁₀ monohydric alcohol or a C ₂ to C ₁₂ dihydric alcohol. Specifically, the alcohol-based solvent is ethanol, propanol, butanol, pentanol, hexanol, isopropyl alcohol, amyl alcohol, 4-methyl-2-pentanol, cyclohexanol, and 3,3,5-trimethylcyclohexanol. , furfuryl alcohol, benzyl alcohol, diacetone alcohol, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol.

The ether-based solvent may include at least one selected from the group consisting of diethyl ether, dipropyl ether, dibutyl ether, diisoamyl ether, tetrahydrofuran, tetrahydropyran, diphenyl ether, and anisole. .

The ketone-based solvent is acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, 2-heptanone, ethyl-n-butyl ketone, methyl- n-hexyl ketone, di-iso-butyl ketone, trimethylnonanone, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone and acetophenone. It may include at least one selected from the group consisting of.

The amide-based solvent is N,N'-dimethylimidazolidinone, N-methylpyrrolidone, N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N -It may contain at least one selected from the group consisting of methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

The ester-based solvent is selected from the group consisting of ethyl acetate, butyl acetate, benzyl acetate, cyclohexyl acetate, ethyl lactate, ethyl 3-methoxypropionate, butyrolactone, diethyl carbonate, diethyl oxalate, and diethyl phthalate. It may include at least one or more of the following.

The hydrocarbon-based solvent is n-pentane, iso-pentane, n-hexane, iso-hexane, n-heptane, iso-heptane, 2,2,4-trimethylpentane, n-octane, iso-octane, cyclohexane, and methyl. Cyclohexane, benzene, toluene, xylene, mesitylene, ethylbenzene, trimethylbenzene, methylethylbenzene, n-propylbenzene, iso-propylbenzene, diethylbenzene, iso-butylbenzene, triethylbenzene, di-iso-propyl It may contain at least one selected from the group consisting of benzene and n-amylnaphthalene.

The solvent may include water and an organic solvent in a weight ratio of 1:0.2 to 1:4, preferably in a weight ratio of 1:0.3 to 1:2, more preferably in a weight ratio of 1:0.5 to 1:1.8. . When the mixing ratio of water and organic solvent in the solvent has a weight ratio within the above numerical range, not only can a highly hygroscopic substrate with excellent fluid absorption and dehumidification amount be manufactured, but also the efficiency of the manufacturing reaction of the highly hygroscopic substrate can be improved. there is.

The strong base may include at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, cesium hydroxide, calcium hydroxide, barium hydroxide, and strontium hydroxide.

By adding the strong base, the nitrile group included in the substrate can be hydrolyzed into a carboxylate (eg, COO ^- Na ⁺ ) and/or amide group (-CONH ₂ ). In this way, the nitrile group is hydrolyzed and converted into a new hydrophilic functional group, thereby strengthening the hydrophilicity of the substrate containing the functional group, and as a result, a highly absorbent substrate can be manufactured.

According to another embodiment of the present invention, there is provided a superabsorbent substrate manufactured according to the method for manufacturing the superabsorbent substrate, which includes a carboxylate group at least on the surface of the substrate.

When the highly absorbent substrate exists in an aqueous solution atmosphere, the polymer chain expands due to repulsion between ions, and at the same time, the concentration of ions present inside the substrate is higher than that of the external aqueous solution, so that the aqueous solution is absorbed into the substrate by osmotic pressure. You can. In addition, the aqueous solution is absorbed to a certain level due to the length of the cross-chain included in the substrate, and after the polymer chain of the substrate is expanded, the aqueous solution is no longer absorbed and can be trapped inside the substrate.

Hereinafter, the present invention will be described in more detail through examples. However, these examples are only intended to aid understanding of the present invention, and the scope of the present invention is not limited to these examples in any way.

<Examples 1 to 5> Production of highly absorbent fiber 1

In manufacturing superabsorbent fibers, the polymer-containing base material is polyacrylonitrile (PAN) fiber (Taekwang Industry, F6, containing more than 90% CN functional group), the strong base is NaOH (Deoksan Science, 98%), and the solvent. Water was used as the furnace, and high-absorbency fibers were manufactured by varying only the electron beam irradiation dose.

Specifically, 1 g of polyacrylonitrile (PAN) fiber was irradiated with an electron beam at the irradiation dose shown in Table 1 below. The 1M NaOH aqueous solution to be mixed with the PAN was prepared by dissolving 3.2 g of NaOH in water.

Afterwards, the PAN irradiated with the electron beam was reacted with 80 mL of 1M NaOH aqueous solution at 70°C for one day. Next, it was filtered through a sieve, washed with a mixed solution of water and ethanol, and dried in an oven at 60°C for more than 24 hours.

The yield was calculated using Equation 1 below.

[Equation 1]

<Experimental Example 1> Evaluation of absorption characteristics of highly absorbent fiber according to electron beam irradiation dose 1

In order to observe the effect of electron beam radiation dose on the absorption characteristics of superabsorbent fibers, the superabsorbent fibers according to Examples 1 to 5 were soaked in distilled water at room temperature for 30 minutes, then the moisture on the surface of the sample was removed and the weight was measured. And the amount of water absorption was measured using Equation 2 below in comparison with the weight of the fiber before immersion in distilled water.

[Equation 2]

Table 1 below shows the results of measuring the moisture absorption amount of the superabsorbent fibers according to Examples 1 to 5.

Electron radiation dose (kGy) transference number(%) Absorption amount (times) Example 1 - 96.97 11.05 Example 2 100 97.03 17.75 Example 3 200 97.42 13.51 Example 4 300 101.81 16.91 Example 5 400 107.18 22.12

Figure 1 shows the results of measuring the moisture absorption of the superabsorbent polymers according to Examples 1 to 5. The highest absorption characteristics were shown when the electron beam irradiation dose was 400 kGy. Meanwhile, the yield increased in proportion to the electron beam irradiation dose. When the cyano group is replaced with carboxylate (COO ^- Na ⁺ ), it can be dissolved in water when not treated with electron beam due to its high hydrophilicity, whereas when treated with electron beam, a cross-linked structure is formed. It can be confirmed that a larger amount of COO ^- Na ⁺ can be contained by suppressing the phenomenon of dissolution in water.

<Examples 6 to 16> Production of highly absorbent fiber 2

Polyacrylonitrile (PAN) fiber was used as a polymer-containing substrate, NaOH was used as a strong base, and high-absorbency fibers were manufactured by varying only the solvent composition (mixing ratio of water and ethanol).

Specifically, 300 kGy of electron beam was irradiated to 1 g of polyacrylonitrile (PAN) fiber. The 1M NaOH aqueous solution to be mixed with the PAN was prepared by dissolving 3.2 g of NaOH in a solvent, and the solvent was prepared by mixing water and ethanol (99.9%) in the ratio shown in Table 2 below.

Afterwards, the PAN irradiated with the electron beam was reacted with 80 mL of 1M NaOH aqueous solution at 70°C for one day. Then it was filtered and dried.

The yield was calculated using Equation 1 above and is shown in Table 2 below.

<Experimental Example 2> Evaluation of absorption properties of highly absorbent fibers according to solvent components

In order to observe the effect of solvent components on the absorption characteristics of superabsorbent fibers, the superabsorbent fibers according to Examples 6 to 16 were soaked in distilled water at room temperature for 24 hours, then the moisture on the surface of the sample was removed and the weight was measured. And the amount of water absorption was measured using Equation 2 below in comparison with the weight of the fiber before immersion in distilled water.

Meanwhile, the dehumidification rate was calculated using Equation 3 below. The dehumidification rate measurement conditions were measured for 30 hours at room temperature and humidity of 68-70%.

[Equation 3]

Table 2 below shows the moisture absorption and dehumidification rate measurement results of the superabsorbent fibers according to Examples 6 to 16.

Electron radiation dose (kGy) Solvent (wt%) transference number(%) Absorption amount (times) Dehumidification rate (%) ethanol water Example 6 300 0 100 100.47 16.32 3.3 Example 7 8.1 91.9 113.07 23.81 8.5 Example 8 16.5 83.5 135.58 45.04 18.5 Example 9 25.3 74.7 145.95 82.2 51.1 Example 10 34.5 65.5 164.65 96.2 49.0 Example 11 44.2 55.8 175.42 84.48 63.0 Example 12 54.3 45.7 162.87 78.36 64.0 Example 13 64.9 35.1 171.50 67.19 51.3 Example 14 76 24 159.14 61.64 44.9 Example 15 87.7 12.3 144.77 38.17 56.8 Example 16 100 0 101.63 16.7 3.4

Figures 2a to 2c show the measurement results of the yield, water absorption amount, and dehumidification rate of the superabsorbent polymer according to Examples 6 to 16. When water and ethanol are mixed in an appropriate ratio, COO ^- Na ⁺ in the cyano group. It can be seen that the conversion rate was high, resulting in high absorbency and dehumidification.

<Examples 17 to 21> Production of highly absorbent fiber 3

Polyacrylonitrile (PAN) fiber was used as a polymer-containing base material, NaOH was used as a strong base, and a solvent mixed with water and ethanol in a weight ratio of 65.5:34.5 was used, and only the electron beam irradiation dose was varied to produce high-absorbency fiber. was manufactured.

Specifically, 1 g of polyacrylonitrile (PAN) fiber was irradiated with an electron beam at the irradiation dose shown in Table 3 below. The 1M NaOH aqueous solution to be mixed with the PAN was prepared by dissolving 3.2 g of NaOH in a solvent mixed with water and ethanol at a weight ratio of 65.5:34.5.

Afterwards, the PAN irradiated with the electron beam was reacted with 80 mL of 1M NaOH aqueous solution at 70°C for one day. Then it was filtered and dried.

The yield was calculated using Equation 1 above and is shown in Table 3 below.

<Experimental Example 3> Evaluation of absorption characteristics of highly absorbent fiber according to electron beam irradiation dose 2

In order to observe the effect of electron beam radiation dose on the absorption characteristics of superabsorbent fibers, the superabsorbent fibers according to Examples 17 to 21 were soaked in distilled water at room temperature for 6 hours, then the moisture on the sample surface was removed and the weight was measured. And the amount of water absorption was measured using Equation 2 below in comparison with the weight of the fiber before immersion in distilled water.

Table 3 below shows the moisture absorption measurement results of the high-absorbency fibers according to Examples 17 to 21.

Electron radiation dose (kGy) transference number(%) Absorption amount (times) Example 17 - 129.36 44.1 Example 18 100 153.21 46.47 Example 19 200 157.26 76.13 Example 20 300 164.65 61.78 Example 21 400 175.67 53.33

Figure 3 shows the results of measuring the moisture absorption of the superabsorbent polymer according to Examples 17 to 21. Compared to the case where water was used as a solvent as in Examples 1 to 5, water and ethanol were mixed in an appropriate ratio. When a solvent is used, it can be confirmed that there is a higher reaction yield and moisture absorption. In addition, the reaction yield improved proportionally as the electron beam dose increased, but in terms of moisture absorption, it was confirmed that the highest moisture absorption was achieved when a radiation dose of about 200 kGy was irradiated.

Claims (11)

(1) irradiating radiation to a substrate containing a nitrile group-containing polymer; and
(2) mixing the irradiated substrate with a solvent and a strong base;
Including,
The solvent includes water and an alcohol-based solvent in a weight ratio of 1:0.2 to 1:4,
A method for producing a highly absorbent substrate, wherein a carboxylate group is formed from a nitrile group on the surface of the substrate through step (2). In claim 1,
A method for producing a highly absorbent substrate, wherein the substrate containing the nitrile group-containing polymer includes a polyacrylonitrile-based polymer and its derivatives. In claim 1,
The nitrile group-containing polymer includes polyacrylonitrile (PAN), styrene-acrylonitrile copolymer (poly(styrene-co-acrylonitrile), SAN), and acrylonitrile-butadiene copolymer (poly(acrylonitrile-co- butadiene, NBR) and acrylonitrile-butadiene-styrene terpolymer (poly(acrylonitrile-co-butadiene-co-styrene, ABS)). . In claim 1,
A method of producing a highly absorbent substrate, wherein the substrate is a fiber, fabric, or non-woven fabric. In claim 1,
The method of manufacturing a highly absorbent substrate, wherein the radiation includes at least one ionizing radiation selected from the group consisting of electron rays, alpha rays, beta rays, gamma rays, X-rays, and neutron rays. In claim 1,
A method of manufacturing a highly absorbent substrate, wherein the radiation is irradiated at a dose of 50 to 500 kGy. delete In claim 1,
A method of producing a highly absorbent substrate, wherein the alcohol-based solvent includes a C ₁ to C ₁₀ monohydric alcohol or a C ₂ to C ₁₂ dihydric alcohol. delete In claim 1,
The strong base includes at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, cesium hydroxide, calcium hydroxide, barium hydroxide, and strontium hydroxide. A highly absorbent substrate manufactured according to any one of claims 1 to 6, claims 8, and 10,
A highly absorbent substrate comprising a carboxylate group at least on the surface of the substrate.