KR20160056849A - Cross-linked acrylate fiber and fiber structure containing same - Google Patents

Abstract

BACKGROUND ART [0002] Crosslinked acrylate-based fibers are known to have high hygroscopicity and are used in the fields of clothing and industrial materials. However, this fiber has such characteristics that the higher the hygroscopicity, the lower the elasticity and the morphological stability, and thus it is difficult to achieve both high moisture absorption performance and card processability and bulkiness. It is an object of the present invention to provide an absorbent article which has both hygroscopic performance for reducing the hygroscopic heat generation and moisture retention in the field of clothes and bedding that have not been provided in the prior art and balmability for improving warmth, Hygroscopic fibers and fibrous structures containing these fibers. An object of the present invention is achieved by a crosslinked acrylate-based fiber having a crosslinked structure and a carboxyl group of 2 to 10 mmol / g and having a crimp ratio of 7% or more.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a crosslinked acrylate-based fiber and a fiber structure containing the crosslinked acrylate-

The present invention relates to a crosslinked acrylate-based fiber having both excellent properties of crimping performance, in particular, high elasticity and entanglement, and high hygroscopicity.

The crosslinked acrylate-based fibers are known to have harmonic functions such as pH buffering property, antistatic property and water retention property, high moisture absorptive rate, high moisture absorptive rate, high moisture absorptive rate difference, or a warming / humidity controlling function derived therefrom (see, 1, 2), and is used in the fields of clothing and industrial materials.

However, since crosslinked acrylate fibers have a high moisture absorptivity, they are characterized by low bulkiness and shape stability. For this reason, there is a situation in which the card is difficult to be processed and the development of the card is not progressed to applications requiring the batting performance of batting or the like.

Japanese Patent Application Laid-Open No. 7-216730 Japanese Patent Laid-Open No. 5-132858

It is an object of the present invention to provide a fiber having both high moisture absorptive performance and processability or bulky property which has not been provided in the prior art. It is a further object of the present invention to provide a fiber structure that combines hygroscopic performance capable of reducing the hygroscopic heating and damping properties useful in, for example, clothing and bedding fields, and balding properties for improving thermal insulation.

The above object of the present invention is achieved by the following means.

(1) A crosslinked acrylate-based fiber having a crosslinked structure and a carboxyl group of 2 to 10 mmol / g and a crimp ratio of 7% or more.

(2) The crosslinked acrylate-based fiber according to (1), wherein the amount of the carboxyl group is 5 to 10 mmol / g.

(3) The crosslinked acrylate-based fiber according to (1) or (2), which has a crimp ratio of 10% or more.

(4) The crosslinked acrylate-based fiber according to any one of (1) to (3), which has a polyvalent metal ion as a counter ion of a carboxyl group.

(5) The crosslinked acrylate-based fiber according to any one of (1) to (4), wherein a carboxyl group is present in the entire fiber.

(6) Acrylonitrile-based fibers having a side-by-side structure composed of two kinds of acrylonitrile-based polymers obtained by subjecting a crosslinking treatment and a hydrolysis treatment with a nitrogen-containing compound having two or more nitrogen atoms in one molecule (1) to (5), wherein the cross-linked acrylate-based fiber is a crosslinked acrylate-based fiber.

(7) A fiber structure containing the crosslinked acrylate-based fibers according to any one of (1) to (6).

(8) A batting comprising the crosslinked acrylate-based fibers according to any one of (1) to (6).

The crosslinked acrylate-based fiber of the present invention combines high hygroscopicity and bulkiness to reduce the dampness caused by body fluids originating from the body, and realizes a pleasant temperature and humidity environment by keeping warmth. Further, it is possible to facilitate web creation in the card process with entanglement. Such crosslinked acrylate-based fibers of the present invention can be suitably used for clothing, bedding, and the like.

Hereinafter, the present invention will be described in detail. The crosslinked acrylate-based fiber of the present invention is a fiber characterized by having a crosslinked structure and a carboxyl group of 2 to 10 mmol / g and a crimp ratio of 7% or more. The carboxyl group is a factor for manifesting properties such as moisture absorptive and desorptive properties and hygroscopic exothermicity in the crosslinked acrylate type fibers and is 2 to 10 mmol / g, more preferably 5 to 10 mmol / g, and still more preferably 5 to 8 mmol / g. If the amount of the carboxyl group is less than 2 mmol / g, the hygroscopicity is not sufficiently obtained in a fiber structure mixed with other fibers, and if it exceeds 10 mmol / g, it becomes weak when absorbing moisture or absorbing, .

The crimp ratio is defined by JIS L1015. The higher the crimp ratio, the more easily the fibers and the fibers are entangled with each other, and the crimp becomes a fibrous aggregate such as a web, a nonwoven fabric, and a spun yarn. The crimp ratio of the fibers of the present invention is 7% or more, preferably 10% or more. If the crimp ratio is less than 7%, the connection of the fibers in the card process is deteriorated, and the lamination property of the fiber aggregate is low, and a shape having sufficient thickness in batting mixed with other fibers can not be obtained .

The bulky properties of the crosslinked acrylate-based fibers of the present invention are preferably not less than 35 cm ³ / g, more preferably not less than 40 cm ³ / g, desirable.

The hygroscopicity of the crosslinked acrylate-based fiber of the present invention is preferably 15% or more, more preferably 15% or more, in view of obtaining a significant hygroscopic performance at a practical mixing ratio level in a fiber structure mixed with other fibers Is preferably 25% or more, and more preferably 35% or more. The upper limit of the moisture absorption rate is not particularly limited, but the upper limit is about 70% in view of the limit of the introduction amount of the carboxyl group.

The acrylonitrile-based fiber as the raw material fiber of the crosslinked acrylate-based fiber of the present invention is produced from an acrylonitrile-based polymer in accordance with a known method. The composition of this polymer is preferably 40% by weight or more, more preferably 50% by weight or more, and still more preferably 80% by weight or more, of acrylonitrile. As described later, a cross-linking structure is introduced into the fibers by reacting a nitrile group of an acrylonitrile-based copolymer forming the acrylonitrile-based fiber with a nitrogen-containing compound such as a hydrazine-based compound. The crosslinked structure greatly affects the fiber properties. When the copolymerization composition of acrylonitrile is too small, the crosslinking structure can not be reduced and the physical properties of the fiber are likely to be insufficient. However, when the copolymerization composition of acrylonitrile is in the above range, good results tend to be obtained .

The copolymerization component other than acrylonitrile in the acrylonitrile-based polymer is not particularly limited as long as it is a monomer copolymerizable with acrylonitrile. Specific examples thereof include sulfonic acid group-containing monomers such as methallylsulfonic acid and p-styrenesulfonic acid, (Meth) acrylic acid, itaconic acid, and the like, and monomers such as styrene, vinyl acetate, (meth) acrylic acid ester, and (meth) acrylamide.

As a method for obtaining a crosslinked acrylate-based fiber having a high crimp ratio, a means in which the acrylonitrile-based fiber of the raw material fiber is composed of two or more acrylonitrile-based polymers is effective. For example, by using acrylonitrile-based fibers obtained by combining two kinds of acrylonitrile-based polymers differing in polymerization ratio of acrylonitrile as raw fibers, the amount of crosslinked structure introduced into each acrylonitrile- A difference occurs in the degree of shrinkage during the hydrolysis treatment, and it becomes possible to develop the crimp. The complex structure of the acrylonitrile-based polymer may be either side-by-side bonded or randomly mixed, but it is preferable that two kinds of acrylonitrile-based polymers are bonded side-by-side . In this case, in order to obtain a sufficient crimp ratio, the difference in the polymerization ratio of acrylonitrile of the two acrylonitrile polymers is preferably 1 to 10%, more preferably 1 to 5% The complex proportion of the ronitrile-based polymer is preferably 20/80 to 80/20, more preferably 30/70 to 70/30.

The form of the acrylonitrile-based fiber employed in the present invention may be any form such as a short fiber, a tow, a yarn, a woven fabric, a nonwoven fabric, etc., and may be used in the middle of a manufacturing process or waste fiber.

As the cross-linking agent for introducing the cross-linking structure into the acrylonitrile-based fiber, any conventionally known cross-linking agent can be used, but it is preferable to use the nitrogen-containing compound from the viewpoints of the efficiency of the cross-linking reaction and ease of handling. This nitrogen-containing compound needs to have at least two nitrogen atoms in one molecule. If the number of nitrogen atoms in one molecule is less than 2, crosslinking reaction does not occur. Specific examples of such a nitrogen-containing compound are not particularly limited as long as they are capable of forming a crosslinked structure, but an amino compound or a hydrazine compound having two or more primary amino groups is preferable. Examples of the amino compound having two or more primary amino groups include diamines such as ethylenediamine and hexamethylenediamine, diethylenetriamine, 3,3'-iminovis (propylamine), N-methyl-3,3 ' - triamine compounds such as iminobis (propylamine), triethylenetetramine, N, N'-bis (3-aminopropyl) -1,3-propylenediamine, N, N'- Propyl) -1,4-butylenediamine, and polyamine-based compounds having at least two primary amino groups as polyvinylamine, polyallylamine and the like. Examples of the hydrazine compound 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 upper limit, the cross-linking agent molecules become large, and it may become difficult to introduce a cross-linking structure into the fibers.

The conditions for introducing the crosslinked structure are not particularly limited, and can be suitably selected in consideration of the reactivity of the crosslinking agent and the acrylonitrile-based fiber, the amount of the crosslinked structure, the moisture absorption rate, the moisture absorption rate difference, and the fiber properties. For example, when a hydrazine compound is used as a crosslinking agent, the above-mentioned acrylonitrile-based fiber is immersed in an aqueous solution to which the hydrazine compound is added so that the hydrazine concentration is 0.5 to 40% by weight, , And a method of treating within 5 hours.

The fibers into which the crosslinked structure is introduced are subjected to a hydrolysis treatment with an alkaline metal compound. By this treatment, the nitrile group present in the fiber is hydrolyzed and a carboxyl group is formed. As the specific treatment conditions, the conditions such as the concentration of the treatment agent, the reaction temperature, and the reaction time may be suitably set in consideration of the amount of the carboxyl group described above, and the amount is preferably 0.5 to 10% by weight, more preferably 1 to 5% % Of a treatment agent aqueous solution at a temperature of 50 to 120 ° C for 1 to 10 hours is preferable industrially and in terms of fiber properties. The above-described cross-linking introduction treatment and hydrolysis treatment may be collectively performed by using an aqueous solution containing the respective treatment agents.

Here, in the carboxyl group, there are a salt-type carboxyl group whose counter ion is a cation other than hydrogen ion and an H-type carboxyl group whose counter ion is a hydrogen ion. It is possible to arbitrarily adjust the ratio. In order to obtain a high moisture absorption rate, it is preferable to make at least 40% of the carboxyl groups a salt type carboxyl group.

Examples of the cation constituting the salt-type carboxyl group include alkali metals such as lithium, sodium and potassium, alkaline earth metals such as magnesium and calcium, other metals such as manganese, copper, zinc and silver, and cations such as NH ₄ and amine And one or more species can be selected according to the required characteristics. Particularly, when magnesium, calcium, zinc or the like, which is a multivalent metal ion, is employed, the crimp rate tends to be high, which is preferable. For example, the acrylonitrile-based fibers obtained by bonding two kinds of acrylonitrile-based polymers side by side can be subjected to the above-mentioned cross-linking introduction and hydrolysis to form carboxyl groups, and magnesium, When a polyvalent metal ion such as calcium or zinc is selected, a crosslinked acrylate-based fiber having a crimp ratio of 10% or more tends to be obtained.

Examples of the method for adjusting the ratio of the salt type carboxyl group and the H type carboxyl group to the above range include an ion exchange treatment with a metal salt such as a nitrate salt, a sulfate salt or a hydrochloride salt, an acid treatment with nitric acid, sulfuric acid, hydrochloric acid, formic acid, pH adjustment treatment, and the like.

In the crosslinked acrylate-based fiber of the present invention, by allowing a carboxyl group to be present in the entire fiber, it is possible to introduce more carboxyl groups while suppressing the embrittlement and tackiness of the fiber, . When a large amount of a carboxyl group is present in a portion of a fiber in a concentrated state, the portion may be retracted due to moisture absorption or absorption, or may be tacky.

On the other hand, when the carboxyl group is present only in the fiber surface layer portion, the carboxyl group is hardly present in the fiber center portion, so that the embrittlement due to moisture absorption and the like is suppressed, the fiber is hardly collapsed and the bulky property can be improved. However, as described above, the amount of the carboxyl group is suppressed from the viewpoint of the embrittlement and tackiness of the fiber.

The crosslinked acrylate-based fibers of the present invention obtained as described above have a characteristic of having a high moisture absorptivity and sufficient crimp to obtain practical bulky property and card processability. Therefore, when the crosslinked acrylate-based fiber of the present invention is contained as the constituent fiber of the fiber structure, the bulkiness obtained by the crimping increases the warmth, and the dampness of the body fluids originating from the body is reduced, Is realized.

The crosslinked acrylate-based fibers of the present invention are more useful by forming a fibrous structure, alone or in combination with other materials. The appearance of such a fiber structure includes cotton, thread, letter, fabric, non-woven fabric, pile fabric, and paper. The form of the crosslinked acrylate-based fibers of the present invention in this structure is substantially uniformly distributed by mixing with other materials, but in the case of a structure having a plurality of layers, any one layer Or crosslinked acrylate-based fibers of the present invention may be present in a concentrated state, or crosslinked acrylate-based fibers of the present invention may be distributed in a specific ratio in each layer.

Other materials that can be used in the fiber structure of the present invention are not particularly limited and natural fibers, organic fibers, semisynthetic fibers, and synthetic fibers that are commonly used are used. In addition, inorganic fibers and glass fibers can be employed have. Specific examples thereof include cotton, hemp, silk, wool, nylon, rayon, polyester, acrylic fiber and the like. The other material to be used in combination may be a material such as a feather, resin, or particles.

The fibrous structure of the present invention is an innumerable combination of the appearance type, the containing form and other materials exemplified above. What kind of structure should be used is the function of the final product (for example, recognition of seasonality, mobility, recognition other than mental awareness, filter, curtain or carpet, use as bedclothes, cushions, insoles, etc.) And the method of contributing crosslinked acrylate-based fibers to their expression. For example, if the fibrous structure is cotton, it may be a combination with polyester, wool, feathers and the like. In the case of batting for a quilt, the crosslinked acrylate-based fibers of the present invention and the feathers are mixed at a weight ratio of 5:95 to 75:25.

The method for producing the batting of the present invention is not particularly limited, and a conventional method for producing batting can be applied. For example, it is possible to apply a method of preliminarily mixing and mixing raw material cotton and then processing the web into a web form with a card machine. For the purpose of imparting shape stability, a step of entangling fibers such as a needle punch or a water punch, or a step of inter-fiber bonding using a heat fusion resin may be added.

Example

Hereinafter, the present invention will be described in detail by way of examples. Parts and percentages in the examples are by weight unless otherwise specified. The properties of the examples are evaluated as follows.

(1) Amount of carboxyl group

Approximately 1 g of the fiber sample is immersed in 50 ml of a 1 mol / l hydrochloric acid aqueous solution for 30 minutes. Next, the fiber sample is immersed in water at a bath ratio of 1: 500. After 15 minutes, if it is confirmed that the bath pH is 4 or more, it is dried (if the bath pH is less than 4, it is washed again). Next, approximately 0.2 g of the sufficiently dried fiber sample is precisely weighed (W1 [g]), 100 ml of water is added, 15 ml of a 0.1 mol / l aqueous sodium hydroxide solution, 0.4 g of sodium chloride and phenolphthalein are added and stirred . After 15 minutes, the sample fibers and the filtrate are separated by filtration, and the sample fibers are washed with water until the color of phenolphthalein disappears. The combined amount of wash water and the filtrate is titrated with 0.1 mol / l hydrochloric acid aqueous solution until the color of phenolphthalein disappears, and the amount of hydrochloric acid aqueous solution consumption (V1 [ml]) is obtained. From the obtained measured values, the total amount of carboxyl groups is calculated by the following formula.

Amount of carboxyl group [mmol / g] = (0.1 x 15-0.1 x V1) / W1

(2) 20 ° C × 65% RH moisture absorption rate

Approximately 2.5 g of the fiber sample is dried in a hot-air drier at 105 DEG C for 16 hours, and its weight is measured (W2 [g]). Next, the fiber sample is placed in a constant-temperature and humidity-controlled room at a temperature of 20 DEG C and 65% RH for 24 hours. The weight of the fiber sample thus absorbed is measured (W3 [g]). From these measurement results, the moisture absorption rate at 20 占 폚 占 65% RH is calculated by the following formula.

20 占 폚 占 65% RH Moisture absorption rate [%] = (W3-W2) / W2 占 100

(3) Crimp rate

Measured by JIS L1015.

(4) Expensive (bulky)

Measured by JIS L1097.

(5) Card passing property

A card web is prepared using a sample roller card machine (Model No. SC-300L) manufactured by Daiwa Kikkou Co., Ltd., in which 50 g of a sample fiber having a fiber length of 70 mm is adjusted to a temperature of 30 ± 5 ° C and 50 ± 10% RH. The obtained web shape is evaluated according to the following criteria.

A: A web having sufficient entanglement and free from unevenness is obtained.

?: The entanglement is somewhat insufficient, and the web is stained.

X: The entanglement is remarkably insufficient so that the fibers are not connected to each other and the web is not obtained.

[Example 1]

Acrylonitrile polymer Ap (intrinsic viscosity [?] = 1.5 in 30 占 폚 dimethylformamide) of 90% by weight of acrylonitrile and 10% by weight of acrylic acid methyl ester, 88% by weight of acrylonitrile, % By weight of acrylonitrile-based polymer Bp ([?] = 1.5) were each dissolved in a 48% by weight aqueous solution of sodium laurate to prepare a spinning solution. Each spinning solution is led so that the composite ratio of Ap / Bp is 1/1 in the composite spinning device according to Japanese Patent Publication No. 39-24301, and spinning, washing, drawing, crimping, Side-by-side type raw material fibers obtained by combining polymer Ap and Bp having a fineness of 3.3 dtex were obtained.

This raw material fiber was subjected to a crosslinking introduction treatment at 98 占 폚 for 5 hours in a 20% by weight aqueous solution of hydrazine added with water and washed. The crosslinked fibers were immersed in a 3 wt% nitric acid aqueous solution and subjected to acid treatment at 90 占 폚 for 2 hours. Subsequently, the resultant was subjected to a hydrolysis treatment at 90 占 폚 for 2 hours in an aqueous 3% by weight sodium hydroxide solution, treated with a nitric acid aqueous solution of 3.5% by weight and washed with water. The obtained fibers were immersed in water and adjusted to pH 11 by the addition of sodium hydroxide and then subjected to an ion exchange treatment by immersing in an aqueous solution of magnesium nitrate corresponding to twice the amount of carboxyl groups contained in the fibers at 50 DEG C for 1 hour Washed with water and dried to obtain crosslinked acrylate-based fibers of Example 1 having Mg salt-type carboxyl groups. The evaluation results of the obtained fibers are shown in Table 1. Further, when the infrared absorption measurement of the fiber was carried out, it was confirmed that the absorption near 2250 cm ^-1 derived from the nitrile group was not observed, the hydrolysis of the nitrile group proceeded throughout the fiber, and the carboxyl group was introduced.

[Examples 2 and 3]

Side-by-side type raw material fibers having a single fiber fineness of 3.3 dtex were obtained in the same manner as in Example 1, except that the compounding ratio of the acrylonitrile-based polymer Ap / Bp was changed in the range shown in Table 1. Using these raw fibers, the treatment after the crosslinking introduction treatment was carried out in the same manner as in Example 1 to obtain crosslinked acrylate fibers of Examples 2 and 3 having Mg salt type carboxyl groups. The evaluation results of these fibers are shown in Table 1. In the infrared absorption measurement of these fibers, absorption at around 2250 cm ^-1 derived from the nitrile group was not observed as in the case of the crosslinked acrylate-based fiber of Example 1.

[Example 4]

A fiber of Example 4 having a Ca salt type carboxyl group was obtained in the same manner as in Example 1, except that calcium nitrate was used instead of magnesium nitrate. The evaluation results of these fibers are shown in Table 1.

[Example 5]

Cross-linking introduction treatment and hydrolysis treatment were simultaneously carried out at 100 占 폚 for 1 hour in an aqueous solution containing 0.5% by weight of hydrazine and 2% by weight of sodium hydroxide in the side-by-side type starting fiber obtained in Example 1, Treated with a nitric acid aqueous solution by weight and washed with water. The obtained fibers were immersed in water, and sodium hydroxide was added thereto to adjust the pH to 9. Then, the fibers were immersed in an aqueous solution of magnesium nitrate corresponding to twice the amount of carboxyl groups contained in the fibers at 50 占 폚 for 1 hour to carry out ion exchange treatment Washed with water and dried to obtain a fiber of Example 5 having an Mg salt type carboxyl group. The evaluation results of the obtained fibers are shown in Table 1. Further, in the infrared absorption measurement of such a fiber, there is absorption at around 2250 cm ^-1 originating from the nitrile group, hydrolysis of the nitrile group proceeds in the fiber surface layer portion, but nitrile groups remain in the fiber center portion .

[Comparative Example 1]

In the same manner as in Example 1, except that only the spinning solution obtained by dissolving the acrylonitrile-based polymer Ap in a 48% by weight aqueous solution of rosadan soda was used, raw fibers composed of polymer Ap having a single fiber fineness of 3.3 dtex were obtained. Using this raw material fiber, the treatment after the cross-linking introduction treatment was carried out in the same manner as in Example 1 to obtain the fiber of Comparative Example 1. The evaluation results of these fibers are shown in Table 1.

[Example 6]

In the same manner as in Example 1 except that the ion exchange treatment with magnesium nitrate was not carried out, the fiber of Example 4 having Na salt type carboxyl group was obtained. The evaluation results of these fibers are shown in Table 2.

[Comparative Example 2]

A fiber of Comparative Example 2 having an Na-type carboxyl group was obtained in the same manner as in Comparative Example 1 except that the ion exchange treatment with magnesium nitrate was not carried out. The evaluation results of these fibers are shown in Table 2.

Example
One Example
2 Example
3 Example
4 Example
5 Comparative Example
One The ratio of polymer Ap 0.5 0.3 0.7 0.5 0.5 1.0 The ratio of polymer Bp 0.5 0.7 0.3 0.5 0.5 0 Counter ion Mg Mg Mg Ca Mg Mg Amount of carboxyl group [mmol / g] 6.56 6.40 6.63 6.42 3.20 6.75 Absorption rate [%] 39.3 40.2 39.7 25.8 15.1 39.1 Crimping rate [%] 15.1 17.1 14.7 11.6 10.4 6.7 Cost (Bulk property) [cm3 / g] 40 41 36 47 53 32

Example
6 Comparative Example
2 The ratio of polymer Ap 0.5 1.0 The ratio of polymer Bp 0.5 0 Counter ion Na Na Amount of carboxyl group [mmol / g] 6.42 6.28 Absorption rate [%] 41.0 40.8 Crimping rate [%] 8.2 3.9 Card processability ○ ×

As can be seen from Table 1, in Examples 1 to 5, since both the high moisture absorption rate and the bulky property are satisfied, it is possible to use as a batting with moisture control function while maintaining warmth. On the contrary, in Comparative Example 1, although the moisture absorption rate is equivalent, the bulkiness is lowered. As can be seen from Table 2, in Example 6, good card processability was obtained, but in Comparative Example 2, the crimp rate was low and the card processability was poor.

Claims (8)

A cross-linking structure and a carboxyl group of 2 to 10 mmol / g, and a crimp ratio of 7% or more. The crosslinked acrylate-based fiber according to claim 1, wherein the amount of the carboxyl group is 5 to 10 mmol / g. The crosslinked acrylate-based fiber according to claim 1 or 2, wherein the crimp ratio is 10% or more. The crosslinked acrylate-based fiber according to any one of claims 1 to 3, which has a polyvalent metal ion as a counter ion of a carboxyl group. The crosslinked acrylate-based fiber according to any one of claims 1 to 4, wherein a carboxyl group is present in the entire fiber. The method according to any one of claims 1 to 5, wherein the acrylonitrile-based fiber having a side-by-side structure composed of two kinds of acrylonitrile-based polymers is prepared by adding a nitrogen-containing compound having two or more nitrogen atoms in one molecule A cross-linking treatment, and a hydrolysis treatment. A fibrous structure containing the crosslinked acrylate-based fibers according to any one of claims 1 to 6. A cotton containing crosslinked acrylate-based fiber according to any one of claims 1 to 6.