JP5051544B2 - Amino group-containing fiber, method for producing the same, and fiber structure containing the fiber - Google Patents

Description

The present invention relates to an amino group-containing fiber. Specifically, the present invention relates to an amino group-containing fiber obtained by reacting an acrylic fiber and an amino group-containing organic compound to simultaneously introduce a crosslinked structure and an amino group.

Acrylic fibers can be subjected to various treatments utilizing the reactivity of nitrile groups in the fibers. Utilizing such characteristics, anion exchange fibers and hygroscopic fibers have been developed. However, each of these fibers has a problem to be solved.

For example, as an anion exchange fiber, polyacrylonitrile fiber is pretreated with hydrazine and sodium hydroxide and then treated with hydrazine or alkyleneamine (Patent Document 1), or heat-treated at a specific temperature. An acid and / or aldehyde-adsorbing fiber (Patent Document 2) obtained by treating the obtained acrylic fiber with polyethylene polyamine or polyethyleneimine for 5 to 10 hours is known. However, in these documents, in order to increase the amination rate, hydrazine cross-linking and introduction of a carboxyl group or a long-time amination treatment is performed as pretreatment, which is disadvantageous in terms of cost.

Patent Document 3 discloses that it is preferable to treat a high nitrile polymer with hydrazine and introduce a crosslinked structure and an amine structure at the same time. However, in this treatment, a large amount of nitrogen-containing functional groups can be introduced. However, an amino group bonded to a group having an electron donating property such as an alkyl group or an alkylene group is not introduced, and the basicity is weaker than that of a general weakly basic anion exchange resin. Since the length is short and dense, practically satisfactory anion exchange ability cannot be obtained.

On the other hand, as a hygroscopic fiber, an acrylate fiber obtained by subjecting an acrylic fiber to cross-linking with a hydrazine compound and hydrolysis with an alkaline metal hydroxide is well known (Patent Document 4). 5). These acrylate fibers have useful moisture absorption properties such as a high saturated moisture absorption rate or a significant change in saturated moisture absorption rate depending on the ambient relative humidity. However, in order to obtain these fibers, at least two steps of a cross-linking step and a hydrolysis step are required, and since the hue of the fiber exhibits a dark pink to dark brown, the use of clothing that emphasizes whiteness, etc. Expansion to is limited.

Regarding the hue, Patent Document 6 discloses that the acid treatment A is performed after the crosslinking treatment with the hydrazine-based compound, and the acid treatment B is performed after the hydrolysis treatment with the alkali. I'm getting fiber. Moreover, in patent document 7, whiteness is improved by implementing a hydrolysis in a substantially oxygen-free atmosphere. However, this technique still requires the two steps of crosslinking and hydrolysis as described above, and further requires a large number of treatment steps, which is disadvantageous in terms of cost.
JP-A-63-75041 JP 2000-64175 A JP-A-10-156179 JP-A-5-132858 JP 2000-314082 A Japanese Patent Laid-Open No. 9-158040 JP 2000-303353 A

The present inventor, in view of such circumstances, as a result of diligent investigation, as a result of treating the acrylic fiber with a specific amino group-containing organic compound, can simultaneously and efficiently introduce a crosslinked structure and an amino group into the fiber, The inventors have found that the obtained fiber has excellent performance and have reached the present invention. An object of the present invention is to provide a fiber having an excellent function obtained by modifying an acrylic fiber, an efficient method for producing the fiber, and a functional fiber structure including the fiber.

The above object of the present invention is achieved by the following means. That is,
[1] A structure in which an acrylic fiber has a total number of amino groups of 3 or more in one molecule, a primary amino group number of 2 or more, and an amino group bonded with an alkylene group of 3 or more carbon atoms. An amino group-containing fiber having an amino group content of 0.5 mmol / g or more, which is a fiber obtained by simultaneously introducing a crosslinked structure and an amino group into a fiber by treating with an amino group-containing organic compound.
[ 2 ] The amino group-containing fiber according to [1], wherein the saturated moisture absorption at 20 ° C. and 65% RH is 15% by mass or more.
[ 3 ] The amino group-containing fiber according to [1] or [2] , wherein the difference in saturated moisture absorption at 20 ° C. 95% RH and 20 ° C. 50% RH is 50 percentage points or more.
[ 4 ] A structure in which the number of all amino groups in one molecule is 3 or more, and the primary amino group is 2 or more, and the amino groups are bonded to each other with an alkylene group having 3 or more carbon atoms. A method for producing an amino group-containing fiber, wherein a cross-linked structure and an amino group are simultaneously introduced into a fiber by reacting an amino group-containing organic compound having the same.
[ 5 ] An anion exchange fiber structure comprising the amino group-containing fiber according to any one of [1] to [ 3 ].
[ 6 ] A hygroscopic fiber structure comprising the amino group-containing fiber according to any one of [1] to [ 3 ].
[ 7 ] An antibacterial fiber structure comprising the amino group-containing fiber according to any one of [1] to [ 3 ].
[ 8 ] An antifungal fiber structure comprising the amino group-containing fiber according to any one of [1] to [ 3 ].

According to the present invention, since a crosslinked structure and an amino group can be introduced into an acrylic fiber in one process, the process can be simplified, and a reduction in manufacturing cost, a reduction in waste, and the like can be expected. In addition, the obtained fiber exhibits good basicity because the introduced amino group is bonded to the alkylene group, and has a high saturated moisture absorption and saturation without re-hydrolysis as in the prior art. It is a fiber that expresses a difference in moisture absorption rate and is less colored. Such an amino group-containing fiber of the present invention can be applied to various uses including the clothing field such as acid gas removal, water desalting, anion exchange, moisture absorption, humidity conditioning, antibacterial, antifungal, etc. It can contribute to the decline.

The present invention is described in detail below. The amino group-containing fiber of the present invention is an acrylic fiber having an alkylene fiber having 3 or more total amino groups in one molecule, 2 or more primary amino groups, and 3 or more carbon atoms between the amino groups. A crosslinked structure and an amino group are simultaneously introduced into the fiber by treating with an amino group-containing organic compound having a structure bonded with a group. Here, the cross-linked structure has an effect of inhibiting the highly hydrophilic amino group-containing fiber from dissolving in water, changing the shape of the fiber, or reducing the strength, and the amino group is anion-exchanged. Contributes to functions such as performance, moisture absorption, antibacterial performance, and antifungal performance.

The acrylic fiber used in the present invention may be a fiber formed of an acrylonitrile (hereinafter referred to as AN) polymer, and the AN polymer may be an AN homopolymer or AN and other monomers. Any of the copolymers can be employed.

In the present invention, since the amino group is introduced by the reaction of the nitrile group of the AN polymer forming the acrylic fiber and the amino group-containing organic compound, when the amount of AN copolymerization is too small, the amino group to be introduced is introduced. The base amount becomes small, and sufficient performance cannot be expressed. For this reason, when the AN copolymerization amount is preferably 40% by mass or more, more preferably 50% by mass or more, and still more preferably 80% by mass or more, good results are easily obtained.

When a copolymer of AN and another monomer is employed as the AN polymer, the copolymer components other than AN include sulfonic acid group-containing monomers such as methallylsulfonic acid and p-styrenesulfonic acid, and the like. Its salts, carboxylic acid group-containing monomers such as (meth) acrylic acid and itaconic acid, and salts thereof, monomers such as styrene, vinyl acetate, (meth) acrylic acid ester, (meth) acrylamide, etc. There is no particular limitation as long as it is a polymerizable monomer. However, when high anion exchange performance is required, the amount of the monomer having an acidic group is preferably small.

The means for producing the acrylic fiber employed in the present invention is not particularly limited, and basically may be produced by applying a known method as it is. The form may be any form such as short fiber, tow, yarn, knitted fabric, non-woven fabric, etc., and may be used as an intermediate product in the manufacturing process, waste fiber, or the like.

In particular, a relatively coarse structure obtained by wet or dry / wet spinning and not subjected to heat treatment such as dry densification or wet heat relaxation treatment, specifically, containing or adhering moisture expressed on the basis of dry fiber mass When the acrylic fiber having a degree of water swelling of 30 to 150% is used, the dispersibility of the fiber in the reaction solution and the permeability of the amino group-containing organic compound into the fiber are increased. , There is an advantage that the reaction proceeds uniformly and rapidly.

The amino group-containing organic compound employed in the present invention is an alkylene group having 3 or more total amino groups in one molecule, 2 or more primary amino groups, and 3 or more carbon atoms between the amino groups. It is necessary to have a structure bonded with. By using such an amino group-containing organic compound, it is possible to simultaneously introduce a crosslinked structure and an amino group in one step. That is, the primary amino group in the compound reacts with the nitrile group in the AN polymer constituting the acrylic fiber, and a crosslinked structure via the compound is formed between the AN polymers. The remaining amino groups that have not been consumed in the crosslinking reaction are immobilized on the acrylic fiber as they are, and excellent anion exchange performance, moisture absorption performance, and the like are exhibited.

Here, in the amino group-containing organic compound, if the total number of amino groups is less than 3, all amino groups are consumed in the crosslinking reaction, and sufficient anion exchange performance and moisture absorption performance are difficult to obtain, and the number of primary amino groups is 2. If it is less than this, it becomes difficult to introduce a crosslinked structure. Further, when the structure is not a structure in which amino groups are bonded by an alkylene group, electron donation to the amino group is small, the basicity becomes insufficient, and sufficient anion exchange performance cannot be obtained.

Specific examples of the amino group-containing organic compound employed in the present invention include 3,3′-iminobis (propylamine), N-methyl-3,3′-iminobis (propylamine), N, N′-bis (3 -Aminopropyl) ethylenediamine, N, N'-bis (3-aminopropyl) -1,3-propylenediamine, N, N'-bis (3-aminopropyl) -1,3-butylenediamine, N, N ' -Bis (3-aminopropyl) -1,4-butylenediamine and the like can be mentioned.

Such an amino group-containing organic compound has a high reaction rate with an acrylic fiber, and can react in a short time even at a treatment temperature of 100 ° C. or lower, so that it is not always necessary to use a pressure vessel, which is advantageous in terms of cost. Furthermore, in the case of an amino group-containing organic compound having such a structure, the fiber after the reaction can be made less colored. The number of carbons referred to here is the number of carbons directly connecting amino groups, and does not include the number of carbons such as branched chains and substituents.

The amino group content of the amino group-containing fiber of the present invention, that is, the anion exchange capacity is 0 . 5mmol / g or more, good Mashiku is 1.0mmol / g or more. If it is 0.5 mmol / g or more, it is a practical level as an anion exchange fiber. Further, although depending on the composition of the acrylic fiber used as a raw material and the amount of the crosslinked structure, the amino group content is 1.0 mmol / g or more to develop the saturated moisture absorption described later, and the amino moisture is used to develop the saturated moisture absorption difference. The base amount is desirably 1.5 mmol / g or more.

The amino group-containing fiber of the present invention can exhibit a saturated moisture absorption rate comparable to that of an acrylate fiber using a conventional carboxyl group, and can adjust the saturated moisture absorption rate over a wide range. In the case of using as a hygroscopic fiber, the saturated moisture absorption rate is preferably 15% by mass or more, more preferably 20% by mass or more in an atmosphere of 20 ° C. and 65% RH.

In addition, the amino group-containing fiber of the present invention is one of the major features that the saturated moisture absorption rate varies greatly depending on the relative humidity. That is, in the amino group-containing fiber of the present invention, it is possible to develop a humidity control property of absorbing moisture when the atmospheric humidity is high and releasing moisture when the atmospheric humidity is low. When used as a humidity control material, it is desirable that the difference in saturated moisture absorption between the 20 ° C. and 95% RH atmosphere and the 20 ° C. and 50% RH atmosphere be 50 percentage points or more.

As for the amount of the cross-linked structure, it is desirable in practical use that the tensile strength of the obtained fiber is 0.4 cN / dtex or more and the tensile elongation is 15% or more.

The amount of the amino group can be adjusted by the type of the amino group-containing organic compound to be employed, that is, the number of amino groups and the amount of introduction of the compound. Further, the amount of the crosslinked structure tends to increase in proportion to the amount of amino groups. However, it is also possible to adjust the balance between the amount of the crosslinked structure and the amount of amino groups by selecting the type of amino group-containing organic compound to be employed. For example, if a compound having many secondary or tertiary amino groups in one molecule is used, the cross-linking structure can be reduced while increasing the amount of amino groups. On the other hand, if a compound having a small number of amino groups in one molecule is used, the cross-linking structure can be increased while reducing the amount of amino groups.

The method for treating the acrylic fiber with the amino group-containing organic compound is not particularly limited, but an aqueous solution of the amino group-containing organic compound is prepared and the acrylic fiber is immersed in the aqueous solution, or the acrylic fiber. And a method of spraying or coating the aqueous solution.

The conditions for treating the acrylic fiber with the amino group-containing organic compound are not particularly limited, and the reactivity between the amino group-containing organic compound to be used and the acrylic fiber, the desired amino group amount and the amount of the crosslinked structure, that is, anion exchange It can be appropriately selected in consideration of performance, saturated moisture absorption, saturated moisture absorption difference, fiber physical properties, and the like. For example, in the case of the method of immersing the acrylic fiber in the amino group-containing organic compound aqueous solution, when the concentration of the amino group-containing organic compound aqueous solution is 10% by mass or more based on the acrylic fiber, It is easy to obtain an amino group amount of 0.5 mmol / g or more.

In addition, the reaction temperature varies depending on the type of amino group-containing organic compound used, but if it is too low, the reaction rate becomes slow and a long reaction time is required. There is a concern about the decomposition of the amino group-containing organic compound. Therefore, preferable results are often obtained when the reaction is preferably performed at 50 to 150 ° C, more preferably at 80 to 150 ° C. Regarding the reaction time, although depending on the reaction temperature and the like, the desired amount of the crosslinked structure and amino group can be introduced usually in about 30 minutes to 48 hours. In particular, in the amino group-containing organic compound employed in the present invention, when the amino group has a structure in which the amino groups are bonded by an alkylene group having 3 or more carbon atoms, the desired amount of the crosslinked structure is about 30 minutes to 4 hours. An amino group can be introduced.

The above-described amino group-containing fibers of the present invention have not only anion exchange performance and moisture absorption performance, but also express functions such as acid gas removal, humidity conditioning, antibacterial properties, and antifungal properties by applying these performances. Is. In particular, for antibacterial and antifungal properties, acrylic fiber, 3,3′-iminobis (propylamine) and N-methyl-3,3′-iminobis (propylamine), which are raw materials for the amino group-containing fiber of the present invention, are used. Even though amino group-containing organic compounds such as these exhibit only weak antibacterial and antifungal properties when used alone, they can provide excellent antibacterial and antifungal properties by using the amino group-containing fiber of the present invention. Can do.

Examples of the method of incorporating the amino group-containing fiber of the present invention into the fiber structure of the present invention include a method of forming a fiber structure using the amino group-containing fiber obtained as described above, and the amino structure of the present invention. Examples include a method of introducing a crosslinked structure and an amino group into an acrylic fiber in the fiber structure by performing the above-described treatment on a fiber structure created using an acrylic fiber as a raw material for the group-containing fiber. be able to.

The appearance of the fiber structure of the present invention includes yarns, yarns, filaments, woven fabrics, knitted fabrics, non-woven fabrics, paper-like materials, sheet-like materials, laminates, and cotton-like materials. Is provided. In these fiber structures, the amino group-containing fiber of the present invention may be used alone, but used in combination with other functional fibers, activated carbon fibers, general natural fibers, synthetic fibers, or the like. Is also possible.

The fiber structure containing the amino group-containing fiber of the present invention can be used as an anion exchange fiber structure, a hygroscopic fiber structure, an antibacterial fiber structure, an antifungal fiber structure, and the like. Specifically, water softening, water and seawater desalination using anion exchange performance, or chemical filters, cigarette filters, adsorbents for water purifiers, filtration fibers, ion exchange filter materials for nuclear power plants, deodorization Can be used as a material. In addition, using moisture absorption performance, anti-condensation materials, moisture absorption / release materials (clothing, building materials, wallpaper, batting, etc.), environmental humidity control, temperature control materials, or dry materials such as closets, basements, floors, bathrooms, It can be used as a part of a coating material such as an electronic material that is very disliked by moisture. Furthermore, it can be used as socks, insoles, shoe lining materials, towels, bath mats, air conditioner filters, humidifier transpiration plates, wallpaper, etc. utilizing antibacterial and antifungal properties.

Hereinafter, the present invention will be described specifically by way of examples. The scope of the present invention is not limited in any way by the description of these examples. Unless otherwise indicated, parts and percentages in the examples are based on mass. The amino group amount, saturated moisture absorption rate, saturated moisture absorption difference, tensile strength, and tensile elongation were determined by the following methods.

(1) Amino group content (anion exchange capacity)
About 0.5 g of a sufficiently dried sample is precisely weighed (X [g]) and immersed in a beaker containing a 0.1 N hydrochloric acid standard solution (Z [ml]) in an amount sufficient for ion exchange. The sample is filtered and a phenolphthalein solution is added to the filtrate as an indicator. The filtrate was titrated with 0.1N sodium hydroxide standard aqueous solution to quantify residual hydrochloric acid. At that time, the titration amount of 0.1N sodium hydroxide standard aqueous solution is Y [ml], the hydrochloric acid standard solution factor is f [HCl], and the sodium hydroxide standard solution factor is f [NaOH]. Base weight was calculated.

Amino group amount [mmol / g] = (0.1 × Z × f [HCl] −0.1 × Y × f [NaOH]) / X

(2) Saturated moisture absorption and saturated moisture absorption difference Weigh about 5 g of a sufficiently dried sample (W1 [g]). The sample is allowed to stand for 24 hours at 20 ° C. and a predetermined relative humidity (50% RH, 65% RH and 95% RH). The mass of the sample thus absorbed is measured (W2 [g]). From the above measurement results, the saturated moisture absorption rate at each relative humidity was calculated by the following equation.

Saturated moisture absorption [%] = (W2-W1) / W1 × 100

The difference in saturated moisture absorption is the difference between the saturated moisture absorption at 20 ° C. and 50% RH and the saturation moisture absorption at 20 ° C. and 95% RH determined as described above.

(3) Tensile strength JIS L 1015 7.7 Tensile strength and elongation rate 7.7.1 According to the standard time test, the value calculated as the tensile strength was defined as tensile strength [cN / dtex].

(4) Tensile elongation JIS L 1015 7.7 Tensile strength and elongation rate 7.7.1 According to the standard time test, the value calculated as the elongation rate was defined as tensile elongation [%].

(Production of acrylic fiber A)
A spinning stock solution prepared by dissolving 10 parts of an AN polymer consisting of 88% AN and 12% vinyl acetate (intrinsic viscosity [η]: 1.2 in 30 ° C. dimethylformamide) in 90 parts of a 48% aqueous rhodium soda solution is spun according to a conventional method. Then, washing with water, stretching, drying, wet heat treatment, and the like were performed to obtain 0.9 dtex acrylic fiber A.

(Production of acrylic fiber B)
A 0.9 dtex acrylic fiber B was obtained in the same manner as the acrylic fiber A, except that the monomer composition was 90% AN and 10% methyl acrylate.

Example 1
10 parts of acrylic fiber A was immersed in 200 parts of an aqueous solution containing 300% methyliminobispropylamine with respect to the fiber, treated at 85 ° C. for 2 hours, washed with water and dried. Anion exchange fibers were obtained. The evaluation results of the fibers are shown in Table 1.

(Examples 2 to 10 , Reference Examples 1 to 6 , Comparative Examples 1 to 8)
In Example 1, it changed into the raw material and conditions shown in Tables 1-3, the fiber of each Example was created, and evaluation was performed. The evaluation results are shown in Tables 1-3.

In Example 1-10, amino group-containing fiber is obtained having good moisture absorbing performance and fiber properties, even have a short reaction time the amino group of a sufficient amount has been introduced.

On the other hand, in the comparative examples, the amino group amount was small and the moisture absorption performance was low. This is because in Comparative Examples 1 to 4, the used amino group-containing organic compound does not have a structure in which amino groups are bonded to each other with an alkylene group having 3 or more carbon atoms. Since it is low, the reaction rate becomes slow, and it is considered that the reaction did not proceed sufficiently within the set reaction time. Further, in Comparative Example 6, since the amount of the amino group-containing organic compound added is small, the amount of amino groups is considered to be insufficient. In Comparative Example 7, since the number of amino groups of the amino group-containing organic compound is 2, most of the amino groups are consumed in the crosslinking reaction, and the performance is considered to be insufficient. In Comparative Example 8, since the number of amino groups of the amino group-containing organic compound is 1, a crosslinked structure is not formed, and it is considered that the fiber properties are insufficient.

(Example 11 )
A nonwoven fabric having a basis weight of 65 g / m ² was obtained with 10% polypropylene fiber and 90% acrylic fiber A. 11 parts of the nonwoven fabric is immersed in 200 parts of an aqueous solution containing 300% methyliminobispropylamine with respect to the acrylic fiber A in the nonwoven fabric, treated at a treatment temperature of 115 ° C. for a treatment time of 2 hours, washed with water and dried. A nonwoven fabric containing group-containing fibers was obtained. The amino group content of the obtained nonwoven fabric was 2.2 mmol / g.

(Examples 12 to 14 )
The amino group-containing fiber obtained in Example 2 was subjected to an acetic acid gas adsorption test. First, the dried fibers of the amount shown in Table 4 are allowed to stand for 10 hours or more in an atmosphere of 20 ° C. and 65% RH to adjust the temperature and humidity. This fiber is put into a Tedlar (registered trademark) bag, sealed, vented, and filled with 1.5 liters of air at 20 ° C. and 65% RH. Next, acetic acid gas was injected into the bag so as to have an initial concentration of 100 volume ppm, and after standing at 20 ° C. for 3 hours, acetic acid remaining using a gas detector tube (measuring range: 1 to 100 volume ppm). The gas concentration was measured. The results are shown in Table 4. It was confirmed that the amino group-containing fiber according to the present invention has excellent removal performance against acetic acid gas.

(Examples 15 to 18 , Reference Example 7 )
Two types of non-woven fabrics having a basis weight of 320 g / m ² prepared using each of the amino group-containing fibers obtained in Example 10 and Reference Example 6 alone, and the amino group-containing fibers and polyester fibers obtained in Example 9 (Toyobo Co., Ltd.) ) Made of EE7) at 3/320 g / m ² non-woven fabrics with 50/50, 30/70 and 10/90 blend rates, tested for mold resistance in accordance with test method B of JIS Z 2911 plastic products. went. As shown in Table 5, it was confirmed that the fiber structure containing the amino group-containing fiber according to the present invention has excellent antifungal performance. The mold resistance was judged according to the following criteria.

<Change in mold growth over time>
-: Mold growth not recognized ±: Mold growth is not observed with the naked eye, but is observed under a microscope + to +++: Mold growth is remarkable with the naked eye

<Mold resistance display>
0: growth of mold is not observed with the naked eye and under the microscope 1: growth of mold is not observed with the naked eye, but is observed under the microscope 2: growth of mold is within 25% of the sample area 3: growth of mold 25-50% of sample area
4: Mold growth is 50-100% of sample area
5: Mycelium grows violently and covers the entire sample

(Example 19 )
The amino group-containing fiber obtained in Example 9 was subjected to an antibacterial test using Escherichia coli and Staphylococcus aureus according to JIS L1902 quantitative test (bacterial solution absorption method). The number of viable bacteria was measured by the pour plate culture method, a standard cloth was used as the unprocessed cloth, and the bacteriostatic activity value and the bactericidal activity value were determined by the following formulas.
Bacteriostatic activity value = log B-log C
Bactericidal activity value = log A−log C
Here, A = the number of bacteria recovered immediately after inoculation of the unprocessed cloth, B = the number of bacteria recovered after 18 hours of incubation of the unprocessed cloth, and C = the number of bacteria recovered after 18 hours of incubation of the sample.

As a result, the amino group-containing fiber obtained in Example 9 has a bacteriostatic activity value “> 4.7” against E. coli, a bactericidal activity value “> 1.5”, and a bacteriostatic activity value against Staphylococcus aureus. It had “> 4.1” and bactericidal activity value “> 1.5”. According to the fiber product certification standards of the Japan Textile Evaluation Technology Association, antibacterial and deodorant processing has a bacteriostatic activity value “> 2.2”, and bactericidal processing (general use) has a bactericidal activity value “≧ 0”. It was confirmed that the amino group-containing fiber according to the invention has excellent antibacterial performance.

Claims (8)

An amino group having a structure in which an acrylic fiber has a total number of amino groups of 3 or more in one molecule, a primary amino group number of 2 or more, and an amino group bonded with an alkylene group of 3 or more carbon atoms. An amino group-containing fiber obtained by treating a crosslinked organic compound and an amino group simultaneously in the fiber by treating with the containing organic compound, wherein the amino group amount is 0.5 mmol / g or more. 2. The amino group-containing fiber according to claim 1 , wherein the saturated moisture absorption at 20 ° C. and 65% RH is 15% by mass or more. The amino group-containing fiber according to claim 1 or 2, wherein a difference in saturated moisture absorption at 20 ° C 95% RH and 20 ° C 50% RH is 50 percentage points or more. An amino group having a structure in which the total number of amino groups in one molecule is 3 or more, and the number of primary amino groups is 2 or more, and the amino groups are bonded to each other with an alkylene group having 3 or more carbon atoms. A method for producing an amino group-containing fiber, wherein a cross-linked structure and an amino group are simultaneously introduced into the fiber by reacting the containing organic compound. The anion exchange fiber structure containing the amino group containing fiber in any one of Claims 1-3 . A hygroscopic fiber structure comprising the amino group-containing fiber according to any one of claims 1 to 3 . The antibacterial fiber structure containing the amino group containing fiber in any one of Claims 1-3 . The anti-fungal fiber structure containing the amino group containing fiber in any one of Claims 1-3 .