JP2019065446A - Moisture release cooling fiber and fiber structure containing the fiber - Google Patents

Abstract

The conventional moisture-releasing cooling effect is small and does not last, so that it is difficult to realize the moisture-releasing cooling effect. An object of the present invention is to provide a fiber and a fiber structure that have a large moisture-releasing cooling effect and can be sustained. A moisture-releasing cooling fiber, wherein a cooling temperature (ΔT30) determined by the following evaluation method is 1.5 ° C. or higher. (Evaluation method) A fiber is used as a card web, 2.5 g is cut out from the card web, folded into a size of 16 cm × 9 cm, and used as a measurement sample. The measurement sample is allowed to stand for 16 hours in an atmosphere having an air temperature of 35 ° C. and a relative humidity of 90%. Next, an electronic thermometer sensor is inserted into the central portion of the measurement sample, and the temperature is changed to an atmosphere with an air temperature of 20 ° C. and a relative humidity of 45%. read. From this result, ΔT30 is obtained by the following formula 1. [Formula 1] ΔT30 [° C.] = 20−t30 [Selection] None

Description

The present invention relates to a moisture releasable cooling fiber and a fiber structure containing the fiber.

In moisture cooling, when the water adsorbed in the substance vaporizes and evaporates (ie, releases moisture), the temperature of the substance is lowered (that is, it is cooled) by depriving the substance of heat of vaporization. ) Say about the phenomenon. When fibers having moisture-removal and cooling properties are used for applications such as clothes and bedding, a cooling effect on the human body can be expected.

For example, Patent Document 1 discloses a fabric containing polyester fibers processed by polymerizing a hydrophilic compound on the fiber surface, and the temperature rise due to heat generation by moisture absorption is 0, as compared to a fabric containing fibers before processing. A hygroscopic / dehumidified / coolable fabric is disclosed which has a temperature of at least 5 ° C. and a temperature drop of at least 0.5 ° C. due to dehumidifying and cooling.

Further, Patent Document 2 is a fabric comprising 60% by weight or more of hydrophobic synthetic fibers, and high moisture absorbing and releasing organic fine particles comprising an acrylic polymer having a salt type carboxyl group and a crosslinked structure are graft-polymerized on the fiber surface. Discloses a moisture-absorbing and releasing fabric characterized in that it is bonded by the above, and the fabric is described to have a moisture-releasing cooling effect.

Furthermore, FIG. 5 of Patent Document 3 and paragraphs [0005] to [0007] of Patent Document 4 disclose that the cross-linked acrylate fiber has a moisture cooling function.

JP, 2002-88653, A Japanese Patent Application Laid-Open No. 2002-38375 JP-A-9-59872 Unexamined-Japanese-Patent No. 2004-218111

However, in the techniques of the respective documents described above, there is a problem that it is difficult to realize the dehumidifying cooling effect because the dehumidifying cooling effect is small or does not last. The present invention has been made in view of the current state of the prior art, and an object thereof is to provide a fiber having a large moisture-retaining and cooling effect and capable of being sustained, and a fiber structure containing the fiber.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to achieve the above-mentioned objective, the present inventors discovered that the dehumidification cooling effect was large and could be maintained by the following means, and arrived at this invention.

(1) A moisture-releasing and cooling fiber characterized in that a cooling temperature (ΔT ₃₀ ) determined by the following evaluation method is 1.5 ° C. or higher.
(Evaluation method)
The fiber is used as a carded web, and 2.5 g is cut from the carded web and folded into a size of 16 cm × 9 cm to obtain a measurement sample. The measurement sample is left for 16 hours in an atmosphere of a temperature of 35 ° C. and a relative humidity of 90%. Next, insert the sensor of the electronic thermometer at the center of the measurement sample, move to an atmosphere with a temperature of 20 ° C and a relative humidity of 45%, and show the temperature indicated by the electronic thermometer (t ₃₀ [° C]) when 30 minutes have elapsed Read From this result, ΔT ₃₀ is determined by the following equation 1.
[Formula 1] ΔT ₃₀ [° C.] = 20−t ₃₀

(2) The moisture-cooling fiber according to (1), wherein the cooling temperature (ΔT ₅ ) determined by the following evaluation method is 1.0 ° C. or higher.
(Evaluation method)
The fiber is used as a carded web, and 2.5 g is cut from the carded web and folded into a size of 16 cm × 9 cm to obtain a measurement sample. The measurement sample is left for 16 hours in an atmosphere of a temperature of 35 ° C. and a relative humidity of 90%. Next, insert the sensor of the electronic thermometer at the center of the measurement sample, move to an atmosphere with a temperature of 20 ° C and a relative humidity of 45%, and show the temperature (t ₅ [° C]) indicated by the electronic thermometer when 5 minutes have elapsed. Read From this result, ΔT ₅ is determined by the following equation 2.
[Formula 2] ΔT ₅ [° C.] = 20−t ₅

(3) A core-sheath fiber comprising a surface layer portion mainly composed of a polymer having a crosslinked structure and a carboxyl group, and a central portion mainly composed of an acrylonitrile polymer (1) or ((1) Dehumidifying and cooling fiber as described in 2).
(4) The moisture-cooling fiber according to (3), wherein the numerical value A represented by the following formula 3 is 0.050 or more and less than 0.080.
[Formula 3] A = amount of carboxyl group [mmol / g] possessed by fiber / ratio of area occupied by “surface layer portion having polymer having cross-linked structure and carboxyl group as main component” in fiber cross section [%]

(5) A fiber structure comprising 5% by mass or more of the moisture-resorbable cooling fiber according to any one of (1) to (4).

The moisture-retaining and cooling fiber of the present invention has the characteristics that the moisture-retaining and cooling effect is large and the effect can be sustained. The moisture-cooling fiber of the present invention having such characteristics is suitable, for example, as a material for summer clothing (such as underwear, T-shirts, hats, etc.), or summer bedding (such as skin cushions, batting, batting pads, and laying pads). It can be used.

The present invention will be described in detail below. The moisture-cooling fiber of the present invention exhibits a cooling temperature ΔT ₃₀ of 1.5 ° C. or more, preferably 2.0 ° C. or more, as determined by the evaluation method described later. That is, the moisture-cooling fiber of the present invention maintains a temperature which is lower by 1.5 ° C. or more than the atmospheric temperature even after 30 minutes have passed since the start of moisture release. With such characteristics, the fiber structure using the moisture-resorbable fiber of the present invention can be made excellent in the durability of the cooling effect. Furthermore, if ΔT ₆₀ indicates preferably 1.0 ° C. or more, more preferably 1.5 ° C. or more, the durability of the cooling effect can be further improved.

Also, release moisture cooled fibers of the present invention, described later to evaluate cooling temperature [Delta] T ₅ as determined by method 1.0 ° C. or higher, it is desirable that preferably exhibit a higher 1.5 ° C.. The fact that the cooling temperature ΔT ₅ is 1.0 ° C. or higher indicates that such fibers are cooled to a temperature 1.0 ° C. or more lower than the atmospheric temperature 5 minutes after the start of moisture release. Such characteristics make it possible for the fiber structure using such fibers to obtain a rapid cooling effect.

The moisture-cooling fiber according to the present invention includes a surface layer portion mainly composed of a polymer having a crosslinked structure and a carboxyl group (hereinafter, also simply referred to as "surface portion") and a center mainly composed of an acrylonitrile-based polymer. There can be mentioned a core-sheath fiber having a part (hereinafter, also simply referred to as a "central part"). Here, the term "main component" indicates that the component is the largest component in each of the surface layer portion and the central portion, and in the usual case, each of the above polymers is preferably 90 It occupies more than 95% by mass, more preferably more than 50% by mass. Here, the acrylonitrile polymer constituting the central portion may have a crosslinked structure.

In such a core-sheath fiber, the moisture absorbed by the fiber is released by the highly hydrophilic carboxyl group, but the presence of such a carboxyl group in the surface layer enables efficient release of water, which results in the release of moisture. It becomes easy to obtain the cooling effect. On the other hand, even if a carboxyl group is present in the central part, the moisture absorbed in the central part can not be dehumidified unless it travels a long distance to the fiber surface, so it is difficult to contribute to the dehumidifying and cooling effect.

Further, by constituting the central portion with an acrylonitrile-based polymer, the fiber physical properties do not become too low, it is easy to carry out the spinning process, and the durability at the time of use can be improved. For this reason, in such a core-sheath fiber, the content ratio to the fiber structure can be further increased, and a more excellent moisture cooling effect can be exhibited.

Furthermore, in the above-mentioned core-in-sheath fiber, it is desirable that the numerical value A represented by the following formula 3 is preferably 0.050 or more and less than 0.080, and more preferably 0.055 or more and less than 0.070.
[Formula 3] A = amount of carboxyl group [mmol / g] / ratio of area occupied by surface layer in fiber cross section [%]

Here, the numerical value A is a numerical value correlated with the concentration of the carboxyl group in the surface layer of the fiber, and the larger the numerical value is, the higher the concentration of the carboxyl group which is a functional group having polarity is on the fiber surface . Therefore, the larger the numerical value A, the more the water can be contained in the surface layer of the fiber, and the more the water can be released quickly.

In order to obtain such an effect, the numerical value A is preferably 0.050 or more, more preferably 0.055 or more. However, when the numerical value A is 0.080 or more, the surface layer of the fiber becomes sticky due to moisture absorption, and the fibers are easily fixed to each other, so that trouble occurs in spinning processing or texture is deteriorated by washing or the like. May.

In addition, the moisture releasable cooling fiber of the present invention is saturated in the atmosphere with a saturated moisture absorption rate in an atmosphere with a temperature of 35 ° C. and a relative humidity of 90%, and moves to an atmosphere with a temperature of 20 ° C. and a relative humidity of 45%. It is desirable that the difference in moisture absorption rate after 30 minutes is preferably 10 percentage points or more, more preferably 12 percentage points or more, and still more preferably 14 percentage points or more. The larger the difference in the moisture absorption rate, the higher the rate of dehumidification. If the rate is less than 10 percent points, the above-described cooling temperature may not be sufficiently obtained.

Moreover, as a counter ion of the carboxyl group in the polymer which has a crosslinked structure and a carboxyl group, not only a hydrogen ion but a cation of an alkali metal such as lithium, sodium, potassium or the like, an alkaline earth metal such as magnesium or calcium One or more of cations, cations of other metals such as manganese, copper, zinc and silver, ammonium ions and the like can be selected according to the required characteristics. When a carboxyl group having a counter ion other than such hydrogen ion (hereinafter referred to as a salt type carboxyl group) is present, the above-mentioned saturated moisture absorption difference becomes larger and the dehumidifying rate becomes larger. A great cooling effect can be expected. The amount of such salt type carboxyl groups is preferably 40% or more, more preferably 50% or more, and still more preferably 60% or more, based on the total amount of carboxyl groups. On the other hand, if the amount of salt type carboxyl groups is too large, the fibers tend to be tacky or embrittled during moisture absorption, so the amount is preferably 90% or less, more preferably 80% or less, based on the total amount of carboxyl groups. It is desirable to When sodium ion or potassium ion is selected as the counter ion, the cooling effect can be further enhanced.

Next, as a typical production method of the moisture-releasing and cooling fiber of the present invention, a method of subjecting the surface layer portion of the acrylonitrile-based fiber to a crosslinking introduction treatment and a hydrolysis treatment can be adopted. In addition, about a bridge | crosslinking introduction | transduction process, you may be given not only to a surface layer part but to center part. An acrylonitrile-based fiber to be a raw material can be produced from an acrylonitrile-based polymer by a known method. The acrylonitrile-based polymer preferably contains 50% by mass or more of acrylonitrile, more preferably 80% by mass or more, and still more preferably 85% by mass or more. As described later, since the crosslinked structure is formed by the reaction of the nitrile group of the acrylonitrile polymer and the crosslinking agent, when the content of acrylonitrile in the acrylonitrile polymer is small, the amount capable of introducing the crosslinked structure decreases. The fiber strength may be insufficient in processing and practical use.

A crosslinked structure is introduced to the acrylonitrile fiber as described above. Although a conventionally well-known crosslinking agent may be used for introduction | transduction of a crosslinked structure, it is preferable to use a nitrogen-containing compound from the point of the introduction | transduction efficiency of crosslinked structure. As the nitrogen-containing compound, it is preferable to use an amino compound or a hydrazine compound having two or more primary amino groups. Examples of amino compounds having two or more primary amino groups include diamine compounds such as ethylenediamine and hexamethylenediamine, diethylenetriamine, 3,3'-iminobis (propylamine), N-methyl-3,3'-iminobis ( Triamine compounds such as propylamine), triethylenetetramine, N, N'-bis (3-aminopropyl) -1,3-propylenediamine, N, N'-bis (3-aminopropyl) -1,4- Examples thereof include tetramine compounds such as butylene diamine, polyvinyl amines, polyallylamines and the like and polyamine compounds having two or more primary amino groups. In addition, examples of hydrazine compounds include hydrazine hydrate, hydrazine sulfate, hydrazine hydrochloride, hydrazine hydrobromide, hydrazine carbonate and the like. The upper limit of the number of nitrogen atoms in one molecule is not particularly limited, but is preferably 12 or less, more preferably 6 or less, and particularly preferably 4 or less. When the number of nitrogen atoms in one molecule exceeds the above-mentioned upper limit, the crosslinker molecule may become large and it may become difficult to introduce a crosslink structure into the fiber. The conditions for introducing the crosslinked structure are not particularly limited, and can be appropriately selected in consideration of the reactivity between the employed crosslinking agent and the acrylonitrile fiber, the amount of the crosslinked structure, and the like. For example, in the case of using a hydrazine compound as a crosslinking agent, the acrylonitrile fiber described above is immersed in an aqueous solution in which the above hydrazine compound is added to have a hydrazine concentration of 0.1 to 10% by mass; C., for 2 to 10 hours.

After the crosslinked structure is introduced, hydrolysis treatment with an alkaline metal compound is performed to hydrolyze the nitrile group present in the surface layer of the fiber to form a carboxyl group. As specific treatment conditions, various conditions such as concentration of treatment agent, reaction temperature, reaction time may be appropriately set in consideration of the above-mentioned carboxyl group concentration and the like, but preferably 0.5 to 10% by mass, More preferably, means for treating at a temperature of 80 to 150 ° C. for 2 to 10 hours in an aqueous solution of 1 to 5% by mass of a treatment agent is industrially preferable from the viewpoint of physical properties of fibers. Here, it is preferable that the above-described crosslinking introduction treatment and hydrolysis treatment are simultaneously performed simultaneously using an aqueous solution in which the respective treatment agents are mixed, rather than sequentially performed as described above. Furthermore, in this simultaneous treatment, it is preferable to carry out under mild conditions of a lower concentration of the alkali metal compound than in the prior art, and to carry out subsequent acid treatment under severe conditions under high temperature than in the past. The moisture-cooling fiber obtained in this manner can have a structure in which more carboxyl groups are present in the surface layer portion than in the prior art, and a relatively hard acrylonitrile polymer is preserved in the central portion.

Examples of the counter ion of the formed carboxyl group include those described above. As a method of adjusting to a desired counter ion, ion exchange treatment with metal salt such as nitrate, sulfate or hydrochloride, acid treatment with nitric acid, sulfuric acid, hydrochloric acid, formic acid etc., pH adjustment treatment with alkaline metal compound etc. There is a method of applying

The fiber structure containing the moisture-cooling fiber of the present invention can be formed by the moisture-cooling fiber of the present invention alone or in combination with other fibers. When combined with other fibers, it is preferable to use 5% by mass or more, more preferably 10% by mass or more of the moisture-retaining and cooling fibers of the present invention in terms of effect development. If the usage rate is less than 5% by mass, uniform mixing may be difficult. Moreover, as other fibers that can be combined, for example, feathers, wool, animal hair, silk, cotton, polyester fibers, polypropylene fibers, polyethylene fibers, polyamide fibers, polyurethane fibers, acrylic fibers, cellulose fibers may be mentioned. it can.

Examples of the form of the fiber structure of the present invention include batts, yarns, knitted fabrics, woven fabrics, pile fabrics, non-woven fabrics and the like. More specifically, innerwear, pants, shirts, uniforms, cut-outs, denim, pajamas, bathrobes, leggings, socks, stockings, supporters, belly wraps, gloves, handkerchiefs, towels, scarves, stalls, mufflers, masks, face masks, Hats, pillows, pillowcases, sheets, towel baskets, bedding pads, mats, rugs, carpets, etc. can be mentioned. In the fiber structure of the present invention, the mode of containing moisture-quenchable fibers is substantially uniformly distributed, concentrated in a specific place, distributed at a specific ratio for each place, etc. Is considered.

Examples are given below to facilitate understanding of the present invention, but these are merely illustrative, and the scope of the present invention is not limited by these.

<Evaluation method of cooling temperature>
A sample fiber is used as a carded web, 2.5 g is cut out from the carded web, and it is folded into a size of 16 cm × 9 cm to obtain a measurement sample. The measurement sample is left for 16 hours in an atmosphere of a temperature of 35 ° C. and a relative humidity of 90%. Next, insert the sensor of the electronic thermometer at the center of the measurement sample, move it to an atmosphere with a temperature of 20 ° C and a relative humidity of 45%, and show the temperature indicated by the electronic thermometer (n minutes) Read t _n [° C.]). From this result, ΔT _n is determined by the following equation.
ΔT _n [° C.] = 20-t _n

<Calculation of numerical value A>
1. Proportion of surface cross-sectional area in fiber cross section The sample fiber has a bath ratio of 1:80 in a dyeing bath containing 2.5% of cationic dye (Nichilon Black G 200) and 2% of acetic acid based on the fiber mass. After soaking and boiling for 30 minutes, it is washed with water, dehydrated and dried. The resulting dyed fiber is sliced thinly perpendicular to the fiber axis, and the fiber cross section is observed with an optical microscope. At this time, the central portion of the acrylonitrile-based polymer is dyed black, and the surface layer portion having a large number of carboxyl groups is not fixed sufficiently to the dye but turns green. Measure the diameter (L1) of the fiber in the fiber cross section and the diameter (L2) of the central part dyed black with the part starting to change color from green to black, and the fiber of the surface area cross section according to the following equation Calculate the ratio of cross sectional area. The average value of 10 samples is taken.
Ratio of the surface layer portion cross-sectional area of the fiber cross section [%] = [1 - { (L2 / 2) 2 π / (L1 / 2) 2 π}] × 100

2. About 1 g of carboxyl group weight fiber sample is dipped in 50 ml of 1 mol / l aqueous hydrochloric acid solution for 30 minutes. The fiber sample is then immersed in water at a bath ratio of 1: 500. After 15 minutes, when it is confirmed that the bath pH is 4 or more, it is dried (if the bath pH is less than 4, rinse again with water). Next, about 0.2 g of a sufficiently dried fiber sample is precisely weighed (W1 [g]), 100 ml of water is added, and further 15 ml of 0.1 mol / l aqueous sodium hydroxide solution, 0.4 g of sodium chloride And add phenolphthalein and stir. After 15 minutes, the sample fibers and the filtrate are separated by filtration and the sample fibers are subsequently washed with water until the color of phenolphthalein disappears. The combined wash water and filtrate is titrated with a 0.1 mol / l aqueous hydrochloric acid solution until the color of phenolphthalein disappears, and the consumed amount of the aqueous hydrochloric acid solution (V1 [ml]) is determined. From the measured values obtained, the total amount of carboxyl groups is calculated by the following equation.
Carboxyl group amount [mmol / g] = (0.1 x 15-0.1 x V1) / W1

3. Number A
It calculates with a following formula using the numerical value calculated | required above.
Numerical value A = amount of carboxyl group [mmol / g] / ratio of area occupied by surface layer in fiber cross section [%]

<Hygroscopicity difference (ease of moisture release)>
Approximately 5 g of a sufficiently dried fiber sample is precisely weighed (W1 [g]). The sample is allowed to stand at a temperature of 35 ° C. and a relative humidity of 90% for 16 hours, and the mass of the absorbed sample is measured (W2 [g]). The sample is again allowed to stand under a relative humidity of 90% for 16 hours, immediately moved to an atmosphere with a temperature of 20 ° C. and a relative humidity of 45%, and after 30 minutes, the mass of the sample is measured (W3 [g]) . From the above measurement results, each moisture absorption rate is calculated by the following equation.
Saturated moisture absorption rate [%] = (W2-W1) / W1 × 100 under the temperature 35 ° C, relative humidity 90%
Moisture absorption rate [%] = (W3-W1) / W1 x 100 after 30 minutes of moving under temperature 20 ° C and relative humidity 45%
The moisture absorption rate difference is calculated from the respective moisture absorption rates determined as described above.

<Proportion of salt type carboxyl group>
The amount of H-type carboxyl groups is calculated in the same manner as in the method for measuring the amount of carboxyl groups described above except that the first immersion in 1 mol / l hydrochloric acid aqueous solution and the subsequent immersion (water washing) in water are not performed. By subtracting the amount of H-type carboxyl group from the amount of carboxyl group described above, the amount of salt type carboxyl group is determined, and the ratio to the amount of carboxyl group described above is calculated.

Example 1
90% by mass of acrylonitrile and 10% by mass of acrylic acid methyl ester An acrylonitrile-based polymer (intrinsic viscosity [.eta.] = 1.5 in dimethylformamide at 30.degree. C.) is dissolved in a 48% by mass aqueous solution of rhodanate to prepare a spinning stock solution Prepared. The stock solution for spinning was subjected to spinning, washing with water, drawing, crimping and heat treatment according to a conventional method to obtain an acrylic fiber having a single fiber fineness of 1.7 dtex.

The obtained acrylic fiber is simultaneously subjected to a crosslinking introduction treatment and a hydrolysis treatment at 100 ° C. for 2 hours in an aqueous solution containing 0.5 mass% of hydrazine hydrate and 2.0 mass% of sodium hydroxide, and 8 mass It treated with 100% of nitric acid aqueous solution for 3 hours, and washed with water. The obtained fiber was immersed in water, sodium hydroxide was added to adjust a part of the carboxyl group to a salt form, washed with water, and dried to obtain a moisture-desorbable fiber A with a fineness of 3.0 dtex. . The evaluation results of the obtained fibers are shown in Table 1. In the infrared absorption measurement of such a fiber, absorption occurs near 2250 cm ^-1 derived from a nitrile group, and hydrolysis of the nitrile group proceeds in the fiber surface layer part, but in the fiber center part, the nitrile group is It was confirmed that it remained.

Example 2
In the same manner as in Example 1 except that the concentration of sodium hydroxide was set to 1.5% by mass, a moisture-desorbable cooling fiber B having a fineness of 2.5 dtex was obtained. The evaluation results of the obtained fibers are shown in Table 1.

[Example 3]
A dehumidified / coolable fiber C having a fineness of 3.5 dtex was obtained in the same manner as in Example 1 except that the concentration of sodium hydroxide was 2.5% by mass. The evaluation results of the obtained fibers are shown in Table 1.

Comparative Example 1
A fiber D having a fineness of 4.2 dtex was obtained in the same manner as in Example 1 except that the concentration of sodium hydroxide was 3.5 mass%. The evaluation results of the obtained fibers are shown in Table 1.

[Comparative Examples 2 and 3]
The evaluation results for rayon having a fineness of 1.4 dtex and polyester having a fineness of 1.4 dtex are shown in Table 1.

As can be seen from Table 1, the fibers of Examples 1 to 3 maintain a temperature lower by 1.5 ° C. or more than the atmospheric temperature even after 30 minutes have passed since the start of moisture release, and further, 5 from the start of moisture release. After the lapse of a minute, it is cooled to a temperature lower by 1.0 ° C. or more than the ambient temperature, and has both a rapid cooling property and a continuous cooling property. On the other hand, the fiber of Comparative Example 1 was inferior in cooling property.

Example 4
A spun yarn of cotton count 45/1 was prepared by setting the ratio of the moisture-cooling fiber A and the polyester fiber to 30/70. Moreover, the spun yarn of cotton count 40/1 was created only with cotton. Then, a knitted fabric of a tempura knit was made using these spun yarns. The results obtained by measuring the cooling temperature using the knitted fabric in place of the card web in the method of measuring the cooling temperature described above and the mixing ratios of the respective fibers in the knitted fabric are shown in Table 2.

Comparative Example 4
Using only the cotton spun yarn prepared in Example 4, a woven fabric of Tenshu was prepared, and the results of measuring the cooling temperature using the knitted fabric are shown in Table 2.

The fiber structure using the cooled and moisture-resorbable fiber of the present invention of Example 4 was superior to the fiber structure of 100% cotton of Comparative Example 4 in the cooling characteristics.

Claims (5)

A moisture-cooling fiber characterized in that a cooling temperature (ΔT ₃₀ ) determined by the following evaluation method is 1.5 ° C. or higher.
(Evaluation method)
The fiber is used as a carded web, and 2.5 g is cut from the carded web and folded into a size of 16 cm × 9 cm to obtain a measurement sample. The measurement sample is left for 16 hours in an atmosphere of a temperature of 35 ° C. and a relative humidity of 90%. Next, insert the sensor of the electronic thermometer at the center of the measurement sample, move to an atmosphere with a temperature of 20 ° C and a relative humidity of 45%, and show the temperature indicated by the electronic thermometer (t ₃₀ [° C]) when 30 minutes have elapsed Read From this result, ΔT ₃₀ is determined by the following equation 1.
[Formula 1] ΔT ₃₀ [° C.] = 20−t ₃₀
The moisture-cooling fiber according to claim 1, wherein the cooling temperature (ΔT ₅ ) determined by the following evaluation method is 1.0 ° C. or higher.
(Evaluation method)
The fiber is used as a carded web, and 2.5 g is cut from the carded web and folded into a size of 16 cm × 9 cm to obtain a measurement sample. The measurement sample is left for 16 hours in an atmosphere of a temperature of 35 ° C. and a relative humidity of 90%. Next, insert the sensor of the electronic thermometer at the center of the measurement sample, move to an atmosphere with a temperature of 20 ° C and a relative humidity of 45%, and show the temperature (t ₅ [° C]) indicated by the electronic thermometer when 5 minutes have elapsed. Read From this result, ΔT ₅ is determined by the following equation 2.
[Formula 2] ΔT ₅ [° C.] = 20−t ₅
The core-sheath fiber according to claim 1 or 2, characterized in that it is a core-sheath fiber having a surface layer portion mainly composed of a polymer having a crosslinked structure and a carboxyl group, and a central portion mainly composed of an acrylonitrile polymer. Dehumidifying and cooling fiber.
The moisture-cooling fiber according to claim 3, wherein the numerical value A represented by the following formula 3 is 0.050 or more and less than 0.080.
[Formula 3] A = amount of carboxyl group [mmol / g] possessed by fiber / ratio of area occupied by “surface layer portion having polymer having cross-linked structure and carboxyl group as main component” in fiber cross section [%]
A fiber structure comprising 5% by mass or more of the moisture-resorbable cooling fiber according to any one of claims 1 to 4.