JPH09209268A - Fiber stricture and production of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fiber structure excellent both in moisture absorption and shrink proof properties from a cellulose fiber on which a polymerization process with a hydrophilic vinyl-based monomer and a cross-linking treatment are performed, and a polyester fiber. SOLUTION: This cellulose fiber structure is obtained by impregnating an aqueous solution of pH 6-12 containing 10-30wt.% concentration of a hydrophilic vinyl-based monomer such as 2-acrylamide-2-methylpropane sulfonic acid (salt) and 1-5wt.% polymerization initiator such as ammonium persulfate based on the monomer to a fiber structure such as a half tricot consisting of a mixed spun fiber of a polyester with a cotton, heat-treating at 80-200 deg.C to perform a polymerization process at 2-10wt.% monomer reaction ratio. Before, after or simultaneously to the polymerization process, a cross- linking treatment of the cellulose fiber is conducted by imparting a cellulose reactive- type resin liquid and heat treat or heat treated by exposing to a formaldehyde vapor in the presence of a catalyst so as to obtain a structure having a moisture absorbing property in which ΔMR of the difference of a moisture absorption at temperature of 30 deg.C and at relative humidity of 90%, and the moisture absorption at 20 deg.C and at relative humidity of 65% satisfies the relationship of 0.04×(100-x)<ΔMR<=0.14×(100-x) [where (x) is a wt.% of the polyester fiber in the fiber structure] and a within 1% washing shrinkage (JIS L1042).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber structure which is excellent in hygroscopicity, shrinkage resistance and morphological stability.

[0002]

2. Description of the Related Art Polyester fibers typified by polyethylene terephthalate fibers are excellent in heat resistance, strength characteristics, workability and shrink resistance, and are used in a wide variety of applications including clothing.

However, polyester fibers are considerably inferior to cellulose fibers such as cotton and hemp in hygroscopicity, which is one of the important properties relating to comfort when used for clothing. On the other hand, polyester fibers are superior to cellulose fibers in shrink resistance and strength.

Therefore, in order to make up for the defects of both the polyester fiber and the cellulose fiber, a method of blending or blending them has been conventionally adopted.

However, the fiber structure obtained by mixed spinning or mixed fiber has lower hygroscopicity than the fiber structure obtained from the cellulose fiber alone, and the shrinkage resistance is lower than that of the polyester fiber alone. It was something that was done.

[0006]

SUMMARY OF THE INVENTION The present invention provides a fiber structure composed of polyester fibers and cellulose fibers,
To provide a fiber structure which has higher hygroscopicity than a fiber structure using a conventional polyester fiber and which is excellent in morphological stability, and a method for producing the same, without substantially impairing the shrink resistance of the polyester fiber. With the goal.

[0007]

To achieve this object, the fiber structure of the present invention has the following constitution.

That is, in a fiber structure comprising polyester fibers and cellulose fibers, hydrophilic vinyl monomers are polymerized in the cellulose fibers, and J
A fiber structure characterized by having a washing shrinkage of 1% or less according to ISL 1042.

The method for producing a fiber structure according to the present invention has the following constitution.

That is, before a polymerization processing step in which a fibrous structure using polyester fibers and cellulose fibers is impregnated with an aqueous solution containing a hydrophilic vinyl monomer and a polymerization initiator, heat treatment is performed, and then washing is performed, A method for producing a fiber structure, which comprises cross-linking the cellulose fibers after or at the same time.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.

In the present invention, the polyester fiber includes
A fiber made of a polyester polymer having a fiber-forming property such as polyethylene terephthalate is used. The polyester polymer here includes not only a homopolymer but also a copolymer.

In the present invention, as the cellulose fiber, fibers having a skeleton of cellulose such as cotton, hemp and rayon are used.

The fiber structure of the present invention is a woven fabric, a knitted fabric, a non-woven fabric, or the like obtained by weaving or knitting a yarn in which polyester fibers and cellulose fibers are mixed-spun or mixed-fibered. This is a fiber structure in which a monomer is polymerized, and further, the shrinkage rate by washing according to JIS L1042 is 1% or less.

In the present invention, the hydrophilic vinyl-based monomer has a polymerizable vinyl group in its molecular structure, and has an acidic group such as carboxylic acid or sulfonic acid and / or its salt, hydroxyl group, amide group or the like. A monomer having a hydrophilic group.

Concretely, acrylic acid monomers such as acrylic acid, sodium acrylate, aluminum acrylate, zinc acrylate, calcium acrylate and magnesium acrylate, 2-acrylamido-2-methylpropanesulfonic acid, methacrylic acid. , Allyl alcohol, sodium allyl sulfonate, acrylamide, sodium vinyl sulfonate, sodium methallyl sulfonate, sodium styrene sulfonate and the like can be used. These may be used alone, or 2
More than one species may be used in combination.

Among these, 2-acrylamide-2
-A monomer containing sulfonic acid and / or its salt in the molecular structure of methyl propane sulfonic acid and / or its sodium salt, sodium allyl sulfonate, etc.,
It is preferable in terms of excellent reactivity.

The fibrous structure of the present invention is excellent in hygroscopicity because it comprises polyester fibers, but is composed of cellulose fibers polymerized with the above-mentioned hydrophilic vinyl monomers.

Here, "the hydrophilic vinyl-based monomer is polymerized on the cellulose fiber" means that the hydrophilic vinyl-based monomer is graft-polymerized on the cellulose fiber, and that the inside of the void (the hollow portion or the like) of the cellulose fiber is It means that the hydrophilic vinyl-based monomer is radically polymerized or that the hydrophilic vinyl-based monomer is radically polymerized inside the cellulose single fiber. Incidentally, the fact that the hydrophilic vinyl-based monomer is graft-polymerized or radical-polymerized in the voids of the cellulose fibers or inside the cellulose single fibers makes the hygroscopic durability exceptional and does not hinder the texture of the woven or knitted fabric. preferable. The polymerization of the hydrophilic vinyl-based monomer can be confirmed by, for example, a section staining method. The section staining method is performed as follows. A paraffin-embedded fiber bundle is cut in the direction perpendicular to the fiber axis to prepare a section. This section is deembedded with an organic solvent or the like, then stained with an appropriate dye (for example, a basic dye), and washed with water. The presence of the hydrophilic vinyl polymer can be confirmed by observing this with an optical microscope.

The reaction rate of the hydrophilic vinyl-based monomer with respect to the fiber structure is preferably 2% by weight or more and 20% by weight or less from the viewpoint of obtaining excellent hygroscopicity while maintaining a good texture of the fiber structure. . It is more preferably 4% by weight or more and 17% by weight or less, and further preferably 6% by weight or more and 15% by weight or less. The reaction rate as used herein means the proportion (% by weight) of the weight of the fiber structure increased by the polymerization of the hydrophilic vinyl-based monomer.
0 × [(absolute dry weight of fiber structure after polymerization of hydrophilic vinyl monomer)-(absolute dry weight of fiber structure before polymerization of hydrophilic vinyl monomer)] / (hydrophilic vinyl It is calculated from the absolute dry weight of the fiber structure before the polymerization of the system monomer).

Further, the fiber structure of the present invention is JIS L
It is necessary that the washing shrinkage rate according to 1042 is 1% or less. If the washing shrinkage ratio exceeds 1%, the shape stability after washing becomes poor. More preferably, the washing shrinkage rate is 0.5%.

The fiber structure of the present invention has a temperature of 30.
Moisture absorption rate MR2 of fiber structure at ℃ and humidity of 90%
ΔMR represented by the value obtained by subtracting the moisture absorption rate MR1 (%) of the fiber structure at a temperature of 20 ° C. and a humidity of 65% from (%)
However, it is preferable that the following formula is satisfied.

0.04 × (100-x) <ΔMR ≦ 0.
14 × (100−x) Here, x represents the proportion (% by weight) of the polyester fiber in the fiber structure.

The moisture absorption rate MR1 (%) of the fiber structure at a temperature of 20 ° C. and a humidity of 65% can be considered to be the hygroscopicity of clothes under a standard environment. Moisture absorption rate MR of fiber structure at 90% humidity
2 (%) can be considered to be the hygroscopicity of clothes after light exercise.

The ΔMR of the fiber structure which is substantially composed of the cellulose fibers in which the hydrophilic vinyl monomer is not polymerized is 3.6 to 4.

The fibrous structure of the present invention exhibits high hygroscopicity because the hydrophilic vinyl-based monomer is graft-polymerized on the cellulose fiber, while the hydrophobic polyester fiber itself contains the hydrophilic vinyl-based monomer. Since it does not polymerize, it is possible to retain the shrink resistance, which is a characteristic feature of polyester fibers.

Next, the method for producing the fiber structure of the present invention will be described.

A fiber structure obtained by weaving or knitting a woven fabric, a knitted fabric, a non-woven fabric or the like using a yarn obtained by blending or blending polyester fibers and cellulose fibers contains a hydrophilic vinyl monomer and a polymerization initiator. The fibrous structure of the present invention can be obtained by cross-linking the cellulose fibers before, after, or at the same time as the polymerization processing step of performing the impregnation treatment of the aqueous solution, followed by heat treatment and then washing.

As a method for impregnating a fibrous structure composed of polyester fibers and cellulose fibers with an aqueous solution containing a hydrophilic vinyl monomer and a polymerization initiator, for example, a method of dipping for a certain period of time or a method of padding is used. Can be adopted. The impregnation temperature is not particularly limited and may be room temperature.

In the present invention, a polymerization initiator generally used in radical polymerization is preferably used as the polymerization initiator. Specifically, peroxides such as ammonium persulfate and benzoyl peroxide, azo catalysts and cerium catalysts are preferably used.

The concentration of the hydrophilic vinyl-based monomer in the aqueous solution containing the hydrophilic vinyl-based monomer and the polymerization initiator is
Although not particularly limited, a concentration of 10% by weight or more and 30% by weight or less is preferable from the viewpoint of efficiently carrying out the reaction. 13% by weight
It is more preferably at least 27% by weight, and even more preferably at least 15% by weight and at most 25% by weight.

The concentration of the polymerization initiator in the aqueous solution containing the hydrophilic vinyl-based monomer and the polymerization initiator is not particularly limited, but from the viewpoint of efficiently carrying out the reaction, it is 1 relative to the hydrophilic vinyl-based monomer. The content is preferably 5% by weight or more and 5% by weight or less, more preferably 2% by weight or more and 4% by weight or less.

From the viewpoint of suppressing the deterioration of the strength and physical properties of the fiber structure using the polyester fiber and the cellulose fiber and efficiently carrying out the reaction, the pH of the aqueous solution containing the hydrophilic vinyl monomer and the polymerization initiator. Is preferably 6 or more and 12 or less, and more preferably pH 7 or more and 11 or less.

In the method for producing a fiber structure of the present invention, a heat treatment is carried out after the impregnation treatment, but the heat treatment is essential for carrying out the polymerization reaction. The heat treatment may be dry heat treatment, wet heat treatment or the like without particular limitation. The heat treatment temperature for carrying out this polymerization is not particularly limited, but it is preferably carried out at a temperature of 80 ° C. or higher and 200 ° C. or lower from the viewpoint of efficiently carrying out the polymerization reaction. Heat treatment is performed in one step or in two or more steps. The heat treatment time is determined in consideration of the heat treatment temperature in consideration of the target reaction rate, but is preferably 20 seconds or more and 5 minutes or less.

Furthermore, after this heat treatment, it is necessary to perform washing to remove unreacted monomers and the like adhering to the fiber structure. The washing method is not particularly limited and may be washing with water or washing with hot water, but washing with hot water can be preferably used from the viewpoint of washing efficiency.

The fiber structure obtained by polymerizing in this manner has a higher hygroscopicity than the conventional fiber structure using polyester fiber and cellulose fiber, while hardly impairing the high shrinkage resistance of the polyester fiber. Have.

Further, it is necessary to crosslink the cellulose fibers before, after, or at the same time as the above-mentioned polymerization processing of the hydrophilic vinyl-based monomer.

The method of crosslinking the cellulose fibers is not particularly limited, but a method of treating the fiber structure with a fibrin-reactive resin or a method of exposing the fiber structure to formaldehyde vapor and subjecting it to heat treatment in the presence of a catalyst is used. It can be preferably adopted.

The term "fibrin reactive resin" as used herein means dimethylolethylene urea, dimethylolurone, dimethyloltriazone, dimethylolpropyleneurea, dimethyloldihydroxyethyleneurea and the like.

As a method for treating the fiber structure with the fibrin reactive resin, an aqueous solution of the resin is applied to the fiber structure together with the catalyst by padding or the like, and then heat treatment is performed. The temperature of this heat treatment is not particularly limited, but a temperature of 80 ° C. or higher and 200 ° C. or lower is preferable from the viewpoint of efficiently performing the crosslinking reaction. An inorganic metal salt such as magnesium chloride can be used as the catalyst.

On the other hand, formaldehyde vapor can be obtained by evaporating by heating an aqueous formaldehyde solution or paraformaldehyde. The heat treatment after exposing the fiber structure to this formaldehyde vapor efficiently carries out the crosslinking reaction, and from the viewpoint of ensuring safety,
It is preferably performed at 60 ° C or higher and 160 ° C or lower. An acidic substance such as sulfuric acid or sulfurous acid can be used as a catalyst in that case.

[0042]

EXAMPLES The present invention will be described more specifically below with reference to examples. Each characteristic value in the examples was determined by the following method.

(1) Hygroscopicity The hygroscopicity was left for 24 hours in a thermo-hygrostat under an atmosphere of absolutely dry weight of the fiber structure and temperature 20 ° C., humidity 65% or temperature 30 ° C., humidity 90%. From the weight change with the weight of the subsequent fiber structure, it was determined by the following formula.

Moisture absorption rate (%) = 100 × [(weight of fiber structure after standing at constant temperature and humidity)-(absolute dry weight of fiber structure)] / (absolute dry weight of fiber structure) From the moisture absorption rate MR1 under the conditions of temperature 20 ° C. and humidity 65% and the moisture absorption rate MR2 under the conditions of temperature 30 ° C. and humidity 90%, ΔMR was calculated by the following equation.

ΔMR = MR2-MR1 (2) Reaction rate The reaction rates are the absolute dry weight of the fiber structure before the polymerization of the hydrophilic vinyl monomer and the fiber after the polymerization of the hydrophilic vinyl monomer. It was calculated from the absolute dry weight of the structure by the following formula.

Reaction rate (%) = 100 × [(absolute dry weight of fiber structure after polymerization of hydrophilic vinyl monomer)-
(Absolute dry weight of fiber structure before polymerization of hydrophilic vinyl monomer)] / (Absolute dry weight of fiber structure before polymerization of hydrophilic vinyl monomer) (3) Shrinkage rate JIS L 1042 It was determined by measuring the shrinkage rate (%) after washing as described.

Example 1 Polyester short fibers (single fiber fineness 0.17 tex, cut length 40 mm) and cotton were mixed and spun by a conventional method (mixing ratio:
50% by weight of polyester and 50% by weight of cotton), and a spun yarn of 45 count were obtained. Then, using this spun yarn as warp and weft, a plain woven fabric (warp density 115 yarns / inch, weft density 76 yarns / inch)
inch) was woven.

10 g of this woven fabric was impregnated with 100 g of an aqueous solution containing 20 g of 2-acrylamido-2-methylpropanesulfonic acid and 0.6 g of ammonium persulfate (adjusted to pH 8) and then heat-treated at 160 ° C. for 3 minutes. went. After the heat treatment, it was washed with hot water at 60 ° C. The reaction rate of 2-acrylamido-2-methylpropanesulfonic acid is 8
%Met. After this polymerization process, an aqueous solution containing 6% of dimethylol dihydroxyethylene urea and 2% of magnesium chloride hexahydrate as a catalyst was applied by padding. After that, the fabric is heat treated at 150 ° C. for 3 minutes,
A cross-linking reaction of cotton fibers was performed. The resulting fabric has a ΔMR of 4
%, And the shrinkage rate was 0.3%. This woven fabric had excellent hygroscopicity, excellent shrinkage resistance, and excellent morphological stability.

Example 2 Polyester short fibers (single fiber fineness 0.17 tex, cut length 40 mm) and cotton were mixed and spun by a conventional method (mixing ratio:
Polyester 65% by weight, cotton 35% by weight), and a spun yarn of 45 count were obtained. Then, this spun yarn was woven into a half tricot with 36 gauge.

10 g of this knitted fabric was impregnated with 100 g of an aqueous solution (adjusted to pH 7) containing 20 g of sodium acrylate and 0.4 g of ammonium persulfate, and then 18
Heat treatment was performed at 0 ° C. for 30 seconds. After the heat treatment, washing was performed with hot water at 80 ° C. The reaction rate of sodium acrylate was 4%. After the polymerisation process, the formaldehyde vapor evolved from paraformaldehyde was exposed for 5 minutes in a closed reactor. Then, after sulfurous acid gas was flown into the reactor to expose the cloth, the cloth was treated at 140 ° C. for 3 minutes to cross-link the cotton fiber.

The obtained knitted fabric had a ΔMR of 2.6% and a shrinkage rate of 0.5%. This knitted fabric had excellent hygroscopicity, excellent shrinkage resistance, and excellent morphological stability.

Examples 3 to 5 Example 1 was repeated except that the mixing ratio of polyester fiber was changed. The results are shown in Table 1. All had excellent hygroscopicity and shrink resistance, and were excellent in morphological stability.

[0053]

[Table 1] Examples 6 to 9 The same procedure as in Example 1 was carried out except that the kind of hydrophilic vinyl-based monomer was changed. Table 2 shows the results. All had excellent hygroscopicity and shrink resistance, and were excellent in morphological stability.

[0054]

[Table 2] Examples 10 to 13 The same procedure as in Example 1 was carried out except that the pH of the aqueous solution containing the hydrophilic vinyl monomer and the polymerization initiator was changed. The results are shown in Table 3. All had excellent moisture absorption and shrinkage resistance, and were excellent in morphological stability.

[0055]

[Table 3] Examples 14 to 17 The procedure of Example 1 was repeated, except that the concentration of the hydrophilic vinyl-based monomer in the aqueous solution was changed. The results are shown in Table 4.
All had excellent hygroscopicity and shrink resistance, and were excellent in morphological stability.

[0056]

[Table 4] Examples 18 to 21 The same procedure as in Example 1 was carried out except that the concentration of the polymerization initiator was changed with respect to the hydrophilic vinyl monomer. Table 5 shows the results
Shown in All had excellent hygroscopicity and shrink resistance, and were excellent in morphological stability.

[0057]

[Table 5] Examples 22 to 25 The same procedure as in Example 1 was carried out except that the heat treatment temperature in the polymerization process was changed. Table 6 shows the results. All had excellent hygroscopicity and shrink resistance, and were excellent in morphological stability.

[0058]

[Table 6] Examples 26 to 29 The procedure of Example 1 was repeated, except that the heat treatment temperature during the cross-linking reaction of the cotton fiber was changed. Table 7 shows the results. All had excellent hygroscopicity and shrink resistance, and were excellent in morphological stability.

[0059]

[Table 7] Examples 30 to 33 The same procedure as in Example 2 was repeated except that the heat treatment temperature during the cross-linking reaction of the cotton fiber was changed. Table 8 shows the results. All had excellent hygroscopicity and shrink resistance, and were excellent in morphological stability.

[0060]

[Table 8] Example 34 Polyester short fibers (single fiber fineness 0.17 tex, cut length 40 mm) and cotton were mixed and spun by a conventional method (mixing ratio:
50% by weight of polyester and 50% by weight of cotton), and a spun yarn of 45 count were obtained. Then, using this spun yarn as warp and weft, a plain woven fabric (warp density 115 yarns / inch, weft density 76 yarns / inch)
inch) was woven.

10 g of this woven fabric was padded with an aqueous solution containing 6% of dimethyloldihydroxyethyleneurea and 2% of magnesium chloride hexahydrate as a catalyst. After that, the fabric is heat treated at 150 ° C. for 3 minutes,
A cross-linking reaction of cotton fibers was performed. After performing this crosslinking reaction,
After impregnation with 100 g of an aqueous solution containing 20 g of 2-acrylamido-2-methylpropanesulfonic acid and 0.6 g of ammonium persulfate (adjusted to pH 8), 160
Heat treatment was performed at 3 ° C. for 3 minutes. After the heat treatment, it was washed with hot water at 60 ° C. The reaction rate of 2-acrylamido-2-methylpropanesulfonic acid was 8%.

The resulting woven fabric had a ΔMR of 4% and a shrinkage of 0.3%. This woven fabric had excellent hygroscopicity, excellent shrinkage resistance, and excellent morphological stability.

Example 35 Polyester short fibers (single fiber fineness 0.17 tex, cut length 40 mm) and cotton were mixed and spun by a conventional method (mixing ratio:
50% by weight of polyester and 50% by weight of cotton), and a spun yarn of 45 count were obtained. Then, using this spun yarn as warp and weft, a plain woven fabric (warp density 115 yarns / inch, weft density 76 yarns / inch)
inch) was woven.

10 g of this woven fabric contained 6 g of dimethylol dihydroxyethylene urea, 2 g of magnesium chloride hexahydrate as a catalyst, and 15 g of 2-acrylamido-2-methylpropanesulfonic acid and 0.6 g of ammonium persulfate. 100g aqueous solution (adjusted to pH 8)
After impregnating the same, heat treatment was performed at 160 ° C. for 3 minutes.
After the heat treatment, it was washed with hot water at 60 ° C.

The obtained woven fabric had a ΔMR of 3.7% and a shrinkage of 0.3%. This woven fabric had excellent hygroscopicity, excellent shrinkage resistance, and excellent morphological stability.

Comparative Example 1 The procedure of Example 1 was repeated except that the hydrophilic vinyl monomer and the polymerization initiator were not used. The resulting fabric has a ΔM
R was 1.5% and the shrinkage rate was 0.4%. This fabric had poor hygroscopicity.

Comparative Example 2 The procedure of Example 1 was repeated except that methyl methacrylate was used instead of the hydrophilic vinyl monomer. The obtained woven fabric had a ΔMR of 1.3% and a shrinkage ratio of 0.4%.
This fabric had poor hygroscopicity.

Comparative Example 3 Example 1 except that no crosslinking reaction of the cotton fiber was carried out.
I went the same way. The obtained woven fabric had a ΔMR of 5% and a shrinkage rate of 2%. This woven fabric was inferior in shrink resistance and inferior in morphological stability.

[0069]

EFFECTS OF THE INVENTION According to the present invention, since it has excellent hygroscopicity, it has excellent comfort when worn and is excellent in shrink resistance,
Since the morphological stability is excellent, it is possible to provide a fiber structure which can be widely used for clothing.

Claims (16)

[Claims] 1. A fiber structure comprising polyester fibers and cellulose fibers, wherein the cellulose fibers are polymerized with a hydrophilic vinyl monomer, and JIS L 1 is used.
A fiber structure characterized by having a washing shrinkage of 042 according to 042. 2. A value obtained by subtracting the moisture absorption rate MR1 (%) of the fiber structure at a temperature of 20 ° C. and a humidity of 65% from the moisture absorption rate MR2 (%) of the fiber structure at a temperature of 30 ° C. and a humidity of 90%. The fibrous structure according to claim 1, wherein ΔMR satisfies the following formula. 0.04 × (100−x) <ΔMR ≦ 0.14 × (10
0-x) Here, x represents the ratio (% by weight) of the polyester fiber in the fiber structure. 3. The fiber structure according to claim 1, wherein the reaction rate of the hydrophilic vinyl-based monomer with respect to the fiber structure is 2% by weight or more and 20% by weight or less. 4. The fiber structure according to claim 1, wherein the hydrophilic vinyl-based monomer is a vinyl-based monomer containing sulfonic acid and / or sulfonate. 5. The fiber structure according to claim 1, wherein the cellulose fibers are crosslinked with a fibrin reactive resin and / or formaldehyde. 6. The fiber structure according to claim 1, which has a washing shrinkage ratio of 0.5% or less according to JIS L 1042. 7. A polymerization processing step in which a fibrous structure using polyester fibers and cellulose fibers is impregnated with an aqueous solution containing a hydrophilic vinyl monomer and a polymerization initiator, followed by heat treatment and then washing. A method for producing a fiber structure, which comprises cross-linking the cellulose fibers after or at the same time. 8. The method for producing a fiber structure according to claim 7, wherein the hydrophilic vinyl-based monomer is a vinyl-based monomer containing a sulfonic acid and / or a sulfonate. 9. The method for producing a fiber structure according to claim 7, wherein the pH of the aqueous solution is 6 or more and 12 or less. 10. The method for producing a fiber structure according to claim 7, wherein the concentration of the hydrophilic vinyl-based monomer in the aqueous solution is 10% by weight or more and 30% by weight or less. 11. The method for producing a fiber structure according to claim 7, wherein the polymerization initiator is contained in an amount of 1% by weight or more and 5% by weight or less with respect to the hydrophilic vinyl-based monomer. 12. The method for producing a fiber structure according to claim 7, wherein the heat treatment temperature is 80 ° C. or higher and 200 ° C. or lower. 13. The method for producing a fiber structure according to claim 7, wherein the cellulose is impregnated with a fibrin-reactive resin and then crosslinked by heat treatment. 14. The temperature of the heat treatment is 80 ° C. or higher and 200 ° C.
The method for producing a fiber structure according to claim 13, wherein: 15. The method for producing a fiber structure according to claim 7, wherein the cellulose fibers are exposed to formaldehyde vapor and subjected to heat treatment in the presence of a catalyst to crosslink. 16. The temperature of the heat treatment is 60 ° C. or higher and 160 ° C.
The method for producing a fiber structure according to claim 15, wherein: