Hydrophobized crosslinked moisture-absorbing fiber and fiber structure thereof

Abstract

To solve a problem of a hygroscopic fiber such as rayon, wool or acrylate fiber that when being used as an inner cotton for futon or clothing, bulkiness and a shape of the inner cotton are greatly changed by washing and drying, and to provide a hydrophobized cross-linked hygroscopic fiber that does not cause volume shrinkage and shape change even if being washed and dried, when having been processed into the inner cotton.SOLUTION: A hydrophobized cross-linked hygroscopic fiber includes a hydrophobizing agent that is attached to a hygroscopic cross-linked acrylonitrile-based fiber. A saturation coefficient of moisture absorption under conditions of 20°C×65% RH is 8.0 to 35.0%, a content of an acrylonitrile unit in the hygroscopic cross-linked acrylonitrile-based fiber is 50 wt.% or more, and an amount of the attached hydrophobizing agent is 0.4-2.5 wt.% with respect to a weight of the hygroscopic cross-linked acrylonitrile-based fiber.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a hydrophobized crosslinked moisture-absorbing fiber that has high shape stability against washing (also referred to as "washing durability" in the present invention) when processed into a fiber structure, and a fiber structure using the fiber. [Background technology]

[0002] With the recent increase in awareness of comfort, there is a demand for the development of materials with moisture absorption properties, and development is also being actively conducted in the field of textiles. For example, acrylate fibers obtained by chemically modifying acrylic fibers are known (Patent Document 1). These fibers contain a crosslinked structure and carboxyl groups, and have excellent moisture absorption and moisture-absorbing heat generation properties.

[0003] However, when such acrylate fibers are used as filling for futons or clothing, they have the problem of losing bulk and shape stability due to moisture absorption. To address this issue, it is known that acrylate fibers made from acrylonitrile-based fibers having a side-by-side structure consisting of two types of acrylonitrile-based polymers are effective (Patent Document 2).

[0004] However, when this fiber is used as filling for futons or clothing, there is a problem that the shape of the filling changes significantly upon washing and drying. This is because the problem of loss of bulkiness and shape stability caused by moisture absorption, which is inherent to acrylate fibers, becomes more pronounced during washing and drying processes in which the fibers are immersed in liquid water, and it is thought that this problem cannot be solved by conventional technology. Furthermore, rayon and wool, which are generally known as hygroscopic fibers, also have the same problem of loss of bulkiness and shape stability, and this is thought to be a problem common to hygroscopic fibers. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 5-132858 [Patent Document 2] Patent No. 6247800 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been devised to solve the above-mentioned problems, and its object is to provide a hydrophobic cross-linked moisture-absorbing fiber that, when processed into padding, does not undergo volumetric shrinkage or shape change even after washing and drying. [Means for solving the problem]

[0007] The present inventors have conducted extensive research into methods for resolving the above-mentioned problems, and as a result have found that when acrylic fibers are crosslinked and then hydrolyzed to impart carboxyl groups, a certain amount or more of acrylonitrile remains, and further a hydrophobizing agent is added, thereby obtaining fibers that can provide moisture-absorbing padding that exhibits almost no volumetric shrinkage and can maintain its shape even after washing and drying, and have completed the present invention.

[0008] That is, the present invention has the following features (1) to (3). (1) A hydrophobized crosslinked hygroscopic fiber in which a hydrophobizing agent is attached to a hygroscopic crosslinked acrylonitrile fiber, characterized in that the saturated moisture absorption rate under conditions of 20°C x 65% RH is 8.0 to 35.0%, the content of acrylonitrile units in the hygroscopic crosslinked acrylonitrile fiber is 50 wt% or more, and the amount of the hydrophobizing agent attached is 0.4 to 2.5 wt% based on the weight of the hygroscopic crosslinked acrylonitrile fiber. (2) The hydrophobic crosslinked moisture-absorbing fiber according to (1), wherein the moisture-absorbing crosslinked acrylonitrile fiber has a carboxyl group amount of 1.0 to 5.5 mmol / g. (3) A fiber structure containing the hydrophobized crosslinked moisture-absorbing fiber according to (1) or (2). [Effects of the Invention]

[0009] The hydrophobic crosslinked hygroscopic fiber of the present invention has excellent hygroscopicity while suppressing water absorption, and therefore fillings using the fiber have high hygroscopicity and are suppressed in volume shrinkage and shape change even after washing and drying. The hydrophobic crosslinked hygroscopic fiber of the present invention can be suitably used as fillings for bedding and clothing, which are excellent in comfort and washing durability. [Brief explanation of the drawings]

[0010] [Figure 1] 1 shows images taken with a digital camera of the shapes of samples of some examples and comparative examples before and after washing in an evaluation of shape stability against washing. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described in detail below. The hydrophobic crosslinked moisture-absorbing fiber of the present invention has a saturated moisture absorption rate of 8.0 to 35.0%, preferably 12.0 to 30.0%, and more preferably 18.0 to 28.0% under conditions of 20°C x 65% RH. If the saturated moisture absorption rate is less than 8.0%, it will be difficult to provide comfort to clothing or futons when mixed with other fibers to make padding or nonwoven fabrics. If the saturated moisture absorption rate is higher than 35.0%, it will be difficult to maintain the washing durability of the padding or nonwoven fabric. Note that "20°C x 65% RH" refers to an atmosphere where the temperature is 20°C and the relative humidity is 65%.

[0012] Furthermore, the moisture-absorbing crosslinked acrylonitrile fiber used in the present invention has an acrylonitrile unit content of 50 wt% or more, preferably 55 wt% or more, and more preferably 60 wt% or more. If the acrylonitrile unit content is less than 50 wt%, the fiber becomes too soft when washed, and the shape of the filling cannot be maintained after washing and drying. On the other hand, the upper limit of the acrylonitrile unit content is limited by the amount of carboxyl groups required to achieve the saturated moisture absorption rate described above. When moisture-absorbing crosslinked acrylonitrile fibers are produced by the production method described below, the upper limit of the acrylonitrile unit content is preferably 85 wt% or less. Here, "wt%" means "% by weight."

[0013] The hydrophobizing agent used in the present invention suppresses the water absorption of fibers and is sufficient as long as it prevents the hygroscopic crosslinked acrylonitrile fibers to which the hydrophobizing agent is attached from sinking in liquid water when dropped into the water. Examples of such hydrophobizing agents include silicone-based hydrophobizing agents, fluorine-based hydrophobizing agents, and paraffin-based hydrophobizing agents. Furthermore, cationic hydrophobizing agents capable of ionic bonding with the carboxyl groups of the hygroscopic crosslinked acrylonitrile fibers can also be used to improve durability against repeated washing. Examples of such cationic hydrophobizing agents include amino-modified silicones, amino-modified fluorine compounds, and cationized paraffin wax.

[0014] The amount of the hydrophobizing agent to be added is 0.4 to 2.5 wt%, preferably 0.6 to 2.2 wt%, and more preferably 1.0 to 2.0 wt%, based on the weight of the hygroscopic crosslinked acrylonitrile fiber. If the amount is less than 0.4 wt%, the hydrophobization is insufficient and the intended effect of the present invention regarding washing durability cannot be achieved. If the amount is more than 2.5 wt%, the resulting hydrophobized crosslinked hygroscopic fiber will feel sticky, which will reduce processability when processed into a fiber structure or will cause problems such as contamination of processing equipment.

[0015] Furthermore, the moisture-absorbing crosslinked acrylonitrile fiber used in the present invention preferably has a carboxyl group amount of 1.0 to 5.5 mmol / g, more preferably 1.5 to 5.0 mmol / g, even more preferably 2.0 to 4.5 mmol / g, and most preferably 2.0 to less than 3.5 mmol / g, from the viewpoint of obtaining a sufficient saturated moisture absorption rate and obtaining high washing durability by immobilizing the hydrophobizing agent through ionic bonds.

[0016] The counter ion of the carboxyl group can be one or more selected depending on the required properties from cations of alkali metals such as sodium, potassium, and lithium, cations of alkaline earth metals such as magnesium and calcium, ammonium ions, hydrogen ions, etc. When a carboxyl group having a counter ion other than a hydrogen ion (hereinafter referred to as a salt-type carboxyl group) is present, the saturated moisture absorption amount and moisture absorption rate become larger, improving comfort when used as padding.

[0017] Next, a method for producing the hydrophobic crosslinked hygroscopic fiber of the present invention will be described. A typical production method of the present invention is a method in which a hydrophobic agent is attached to a hygroscopic crosslinked acrylonitrile fiber obtained by subjecting an acrylic fiber to a crosslinking structure introduction treatment and a hydrolysis treatment.

[0018] First, the raw material acrylic fiber can be produced from an acrylonitrile polymer by a known method. Here, the acrylonitrile polymer used is one having an acrylonitrile unit content of 85% by weight or more. If the acrylonitrile unit content is less than 85% by weight, it becomes difficult to achieve an acrylonitrile unit content of 50% by weight or more in the hygroscopic crosslinked acrylonitrile fiber obtained after the crosslinking structure introduction treatment and hydrolysis treatment.

[0019] The acrylonitrile polymer is then processed into fibers by a conventional method to obtain acrylic fibers. A plurality of types of acrylonitrile polymers may be used, for example, acrylic fibers having a side-by-side structure obtained by using two types of acrylonitrile polymers.

[0020] Next, the acrylic fibers are subjected to a crosslinking structure introduction treatment. While conventionally known crosslinking agents may be used in the crosslinking structure introduction treatment, it is preferable to use a nitrogen-containing compound in terms of the efficiency of introducing the crosslinking structure. Examples of such nitrogen-containing compounds include amino compounds having two or more primary amino groups and hydrazine-based compounds. Examples of amino compounds having two or more primary amino groups include diamine-based compounds such as ethylenediamine and hexamethylenediamine, triamine-based compounds such as diethylenetriamine, 3,3'-iminobis(propylamine), and N-methyl-3,3'iminobis(propylamine), tetramine-based compounds such as triethylenetetramine and N,N'-bis(3-aminopropyl)-1,4-butylenediamine, and polyamine-based compounds having two or more primary amino groups, such as polyvinylamine and polyallylamine. Examples of hydrazine-based compounds include hydrazine hydrate, hydrazine sulfate, hydrazine hydrochloride, hydrazine hydrobromide, and hydrazine carbonate. The upper limit of the number of nitrogen atoms per molecule is not particularly limited, but is preferably 12 or less, more preferably 6 or less, and particularly preferably 4 or less. If the number of nitrogen atoms per molecule exceeds the upper limit, the crosslinked molecules become larger, which may make it difficult to introduce a crosslinked structure into the fiber. The conditions for introducing a crosslinked structure are not particularly limited and can be appropriately selected taking into account the reactivity of the crosslinking agent with the acrylic fiber and the amount of crosslinked structure. For example, when a hydrazine-based compound is used as the crosslinking agent, the acrylic fiber may be immersed in an aqueous solution containing the hydrazine-based compound so that the hydrazine concentration is 0.1 to 10 wt %, and treated at 80 to 150°C for 2 to 10 hours.

[0021] After the crosslinked structure is introduced, the fiber is subjected to a hydrolysis treatment with an alkaline metal compound, whereby the nitrile groups in the fiber are hydrolyzed to form carboxyl groups. Specific treatment conditions may be appropriately set, such as the concentration of the treatment agent, reaction temperature, and reaction time, taking into account the amount of carboxyl groups described above. From an industrial and fiber-physical perspective, treatment in a 0.1 to 10 wt % aqueous solution of the treatment agent, more preferably a 0.2 to 5 wt %, solution at a temperature of 80 to 150°C for 2 to 10 hours, is preferred.

[0022] The crosslinking structure introduction treatment and hydrolysis treatment can be carried out in this order as described above, or they can be simultaneously carried out at once using an aqueous solution containing a mixture of the respective treatment chemicals. Furthermore, in this simultaneous treatment, it is preferable to carry out the treatment under milder conditions using an alkaline metal compound at a lower concentration than the conditions described above, and then carry out the subsequent acid treatment under more severe conditions at a high temperature. In the present invention, some of the nitrile groups in the raw acrylic fiber are used in the crosslinking reaction, some are converted to carboxyl groups by hydrolysis, and some remain as nitrile groups. Therefore, it is necessary to set the conditions for the crosslinking structure introduction treatment and the hydrolysis treatment taking into account the content of acrylonitrile units and the amount of carboxyl groups in the hygroscopic crosslinked acrylonitrile fiber.

[0023] The hygroscopic crosslinked acrylonitrile fiber can be obtained as described above. Methods for adjusting the counter ions of the carboxyl groups of the fiber to desired counter ions include ion exchange treatment with metal salts such as nitrates, sulfates, and hydrochlorides; acid treatment with nitric acid, sulfuric acid, hydrochloric acid, and formic acid; and pH adjustment treatment with alkaline metal compounds.

[0024] Next, methods for attaching a hydrophobizing agent to hygroscopic crosslinked acrylonitrile fibers can be generally used, such as spraying a liquid containing the hydrophobizing agent and drying it, or immersing the fiber in a liquid containing the hydrophobizing agent and then drying it. Alternatively, the hydrophobizing agent can be used in an emulsion state in water. Examples of hydrophobizing agents in an emulsion state include commercially available products such as "Asahi Guard GS10" (product name) (AGC Corporation, fluorine-based hydrophobizing agent emulsion), "NK Guard S-09" (product name) (Nicca Chemical Co., Ltd., cationic fluorine-based silicone compound), and "TH-44" (product name) (Nicca Chemical Co., Ltd., high-melting-point wax emulsion).

[0025] The fiber structure of the present invention may use the hydrophobic crosslinked moisture-absorbing fiber of the present invention described above alone or in combination with other fibers. Examples of other fibers include natural fibers such as wool, animal hair, silk, and cotton, and chemical fibers such as polyester fibers, polypropylene fibers, polyethylene fibers, polyamide fibers, acrylic fibers, and regenerated cellulose fibers. The type of fiber structure is not particularly limited, and examples include carded cotton, various nonwoven fabrics, granular cotton, blown cotton, spun yarn, knitted fabrics, woven fabrics, and pile fabrics.

[0026] When other fibers are used in the fiber structure of the present invention, the blending ratio of the hydrophobic crosslinked hygroscopic fiber of the present invention may be set so as to obtain the desired properties depending on the intended use of the fiber structure. For example, when used as batting for a futon or a clothing, the blending ratio of the hydrophobic crosslinked hygroscopic fiber of the present invention to the total weight of the batting is preferably 10.0 to 90.0 wt%, more preferably 20.0 to 80.0 wt%.

[0027] When such a fiber structure using the hydrophobic crosslinked moisture-absorbing fiber of the present invention is used as filling for a futon or filling for clothing, the comfort due to its high moisture absorption can be felt, and the futon or clothing can maintain such comfort even after washing and drying. [Example]

[0028] Examples are given below to facilitate understanding of the present invention, but these are merely illustrative and the gist of the present invention is not limited to these.

[0029] <Method for evaluating saturated moisture absorption rate under conditions of 20°C x 65% RH> Approximately 5.0 g of sample is dried in a hot air dryer at 105°C for 16 hours and the weight (a) is measured. Next, the sample is placed in a thermo-hygrostat set at 20°C and 65% RH for 24 hours to absorb moisture, and then the weight (b) of the sample is measured. From the above measurement results, the weight is calculated using the following formula. Saturated moisture absorption rate [%]={(ba) / a}×100

[0030] <Acrylonitrile unit content measurement method> The content of acrylonitrile units in a sample to be measured is determined by measuring the infrared absorption spectrum of the sample using an infrared absorption spectrometer and comparing it with the infrared absorption spectrum of a sample whose content of acrylonitrile units is known. First, the infrared absorption spectrum of a sample whose content of acrylonitrile units is known (content c [wt%]) is obtained by subtracting the 2943 cm -1 (CH group absorption peak) at 2245 cm -1 Next, calculate the height ratio (1:d) of the CN group absorption peak at 2943 cm from the infrared absorption spectrum of the sample to be measured. -1 (CH group absorption peak) at 2245 cm -1 The height ratio (1:e) of the absorption peak of the CN group is calculated. The obtained value is used to calculate the content of acrylonitrile units in the sample to be measured using the following formula. Acrylonitrile unit content [wt%] = (c × e / d) × 100 The infrared absorption spectrum measuring device used was a Fourier transform infrared spectrophotometer "IRAffinity-1" manufactured by Shimadzu Corporation.

[0031] <Method for measuring the amount of hydrophobizing agent attached> The amount of hydrophobizing agent attached is calculated by the gravimetric method. That is, the weight (f) before the hydrophobizing agent is attached and the weight (h) after the hydrophobizing agent is attached are measured, and the amount of hydrophobizing agent attached is calculated using the following formula. Hydrophobizing agent attachment amount [wt%] = {(hf) / f} × 100 When the hydrophobizing agent is a water dispersion or emulsion, the dry weight after the application treatment, that is, the weight after the water has been evaporated and removed, is taken as the weight after application (h).

[0032] <Method for measuring carboxyl group amount> Approximately 1 g of sample is immersed in 50 ml of 1 mol / L hydrochloric acid solution for 30 minutes. The sample is then immersed in water at a bath ratio of 1:500. After 15 minutes, the bath pH is confirmed to be 4 or higher, and the sample is thoroughly dried (if the bath pH is less than 4, the sample is washed again with water). Approximately 0.2 g of the dried sample is then weighed (W [g]), 100 ml of water is added, and 15 ml of 0.1 mol / L sodium hydroxide solution, 0.4 g of sodium chloride, and phenolphthalein are added and stirred. After 15 minutes, the sample and filtrate are separated by filtration. The filtrate is then titrated with 0.1 mol / L hydrochloric acid solution until the phenolphthalein color disappears, and the amount of hydrochloric acid consumed (V [ml]) is calculated. The amount of carboxyl groups is calculated using the following formula: Carboxyl group amount [mmol / g] = (0.1 × 15 - 0.1 × V) / W

[0033] <Shape stability after washing (size change rate)> After opening the sample with a carding machine, the sample is needle punched to a weight of 100 g / m. 2 This nonwoven fabric is cut into a square of approximately 10 cm x 10 cm in size and the area (j [cm 2 Next, the fabric is washed according to the SEK mark textile product washing method of the Japan Textile Evaluation Technology Council, and then dried in a dryer. After drying, the area of ​​the nonwoven fabric (m [cm 2 The obtained value is used to calculate the size change rate using the following formula. Size change rate [%] = {(mj) / j) × 100 If the size change rate is within ±5%, it can be judged to have good washing durability. Note that, as shown in Figure 1, in some comparative examples, the shape of the nonwoven fabric after washing changed significantly due to wrinkles, kinks, holes, etc., and in such cases it was judged that measurement was not possible.

[0034] Example 1 An acrylonitrile polymer containing 88% by weight of acrylonitrile and 12% by weight of vinyl acetate was dissolved in a 48% by weight aqueous solution of sodium rhodanate to prepare a spinning dope. Spinning, water washing, drawing, crimping, heat treatment, and cutting were performed according to standard wet-process acrylic fiber manufacturing methods to obtain acrylic fibers with a single fiber fineness of 1.7 dtex and a fiber length of 76 mm. The acrylic fibers were simultaneously subjected to crosslinking and hydrolysis treatment at 115°C for 2 hours in an aqueous solution containing 1.0% by weight of hydrazine hydrate and 0.55% by weight of sodium hydroxide, followed by treatment with an 8% by weight aqueous nitric acid solution at 120°C for 3 hours and water washing. The resulting fibers were immersed in water, adjusted to pH 9 with the addition of sodium hydroxide, washed with water, and dried to obtain hygroscopic crosslinked acrylonitrile fibers with sodium salt-type carboxyl groups. The acrylonitrile unit content and carboxyl group content of the hygroscopic crosslinked acrylonitrile fibers were measured, and the results are shown in Table 1.

[0035] The hygroscopic crosslinked acrylonitrile fiber was then immersed in a 0.1% by weight aqueous emulsion of a hydrophobizing agent (product name "S-09" manufactured by Nicca Chemical Co., Ltd.) at a bath ratio of 1:11 at 50°C for 30 minutes, followed by dehydration and drying to obtain a hydrophobized crosslinked hygroscopic fiber. The saturated moisture absorption rate, hydrophobizing agent adhesion amount, and size change rate of the hydrophobized crosslinked hygroscopic fiber were evaluated, and the results are shown in Table 1.

[0036] Examples 2 and 3 The evaluation results of the hygroscopic crosslinked acrylonitrile fibers and hydrophobic crosslinked hygroscopic fibers prepared in the same manner as in Example 1 except that the amount of sodium hydroxide used in the hydrolysis treatment (0.55 wt%) was changed to 0.2 wt% in Example 2 and 1.0 wt% in Example 3 are shown in Table 1.

[0037] Examples 4 and 5 The evaluation results of the hygroscopic crosslinked acrylonitrile fibers and hydrophobic crosslinked hygroscopic fibers prepared in the same manner as in Example 1, except that the concentration (0.1 wt%) of the hydrophobic agent "S-09" manufactured by Nicca Chemical Co., Ltd. was changed to 0.05 wt% in Example 4 and 0.2 wt% in Example 5, are shown in Table 1.

[0038] Example 6 Table 1 shows the evaluation results of the moisture-absorbing crosslinked acrylonitrile fiber and the hydrophobic crosslinked moisture-absorbing fiber prepared in the same manner as in Example 1, except that after sodium hydroxide was added to adjust the pH to 9, a step of treating with an aqueous magnesium sulfate solution was added to convert the Na salt-type carboxyl groups to Mg salt-type carboxyl groups.

[0039] Example 7 Table 1 shows the evaluation results of the moisture-absorbing crosslinked acrylonitrile fiber and the hydrophobic crosslinked moisture-absorbing fiber prepared in the same manner as in Example 1, except that after adjusting the pH to 9 by adding sodium hydroxide, a step of treating with an aqueous calcium nitrate solution was added to convert the Na salt-type carboxyl groups to Ca salt-type carboxyl groups.

[0040] Comparative Examples 1 to 4 The evaluation results were shown in Table 1. The evaluation results were obtained using polyester fiber (3.3 dtex, 51 mm) as Comparative Example 1, rayon (Corona, manufactured by Daiwabo Rayon Co., Ltd., 3.3 dtex, 51 mm) as Comparative Example 2, wool (merino wool, 55 mm) as Comparative Example 3, and the moisture-absorbing crosslinked acrylonitrile fiber of Example 1 (i.e., fiber to which no hydrophobizing agent was attached) as Comparative Example 4.

[0041] Comparative Example 5 The acrylic fiber obtained in Example 1 was subjected to a crosslinking structure introduction treatment at 105°C for 5 hours in an aqueous solution containing 15% by weight of hydrazine hydrate. Subsequently, a hydrolysis treatment was carried out at 90°C for 2 hours in an aqueous solution containing 4.0% by weight of sodium hydroxide. The fiber was then treated with a 4.0% by weight aqueous nitric acid solution at 100°C for 1 hour and washed with water. The obtained fiber was immersed in water, adjusted to pH 9 by adding sodium hydroxide, washed with water, and dried to obtain an acrylate fiber having a sodium salt-type carboxyl group. The acrylonitrile unit content and carboxyl group amount of the acrylate fiber were measured, and the results are shown in Table 1.

[0042] The acrylate fiber was then immersed in a 0.1 wt% aqueous emulsion of a hydrophobizing agent (product name "S-09" manufactured by Nicca Chemical Co., Ltd.) at a bath ratio of 1:11 at 50°C for 30 minutes, followed by dehydration and drying to obtain a hydrophobized acrylate fiber. The saturated moisture absorption rate, hydrophobizing agent adhesion amount, and size change rate of the hydrophobized acrylate fiber were evaluated, and the results are shown in Table 1.

[0043] [Table 1]

[0044] As can be seen from Table 1 and Figure 1, the hydrophobic crosslinked hygroscopic fibers of Examples 1 to 7 exhibit both high hygroscopicity and high shape stability, whereas polyester exhibits high shape stability but insufficient hygroscopicity, and rayon and wool exhibit high hygroscopicity but insufficient shape stability. Furthermore, even hygroscopic crosslinked acrylonitrile fibers with a high acrylonitrile unit content, such as those in Comparative Example 4, exhibit insufficient shape stability unless subjected to hydrophobic treatment. Acrylate fibers with a low acrylonitrile content, such as those in Comparative Example 5, exhibit insufficient shape stability even after hydrophobic treatment. [Industrial Applicability]

[0045] When the hydrophobic crosslinked moisture-absorbent fiber of the present invention is used as a filling, it can provide comfort to a futon or clothing due to its high moisture absorption, and can be used repeatedly and comfortably due to its washing durability.

Claims

1. A hydrophobized crosslinked hygroscopic fiber in which a hydrophobizing agent is attached to a hygroscopic crosslinked acrylonitrile fiber, characterized in that the saturated moisture absorption rate under conditions of 20°C x 65% RH is 8.0 to 35.0%, the content of acrylonitrile units in the hygroscopic crosslinked acrylonitrile fiber is 50 wt% or more, and the amount of the hydrophobizing agent attached is 0.4 to 2.5 wt% based on the weight of the hygroscopic crosslinked acrylonitrile fiber.

2. 2. The hydrophobic crosslinked moisture-absorbing fiber according to claim 1, wherein the moisture-absorbing crosslinked acrylonitrile fiber has a carboxyl group amount of 1.0 to 5.5 mmol / g.

3. A fiber structure comprising the hydrophobic crosslinked moisture-absorbing fiber according to claim 1 or 2.

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