JP3270226B2 - Sheath-core type composite fiber, fiber structure and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheath-core composite fiber, a fiber structure, and a method for producing the same, which exhibit excellent hygroscopicity. More specifically, the present invention relates to a novel sheath-core type composite fiber, a fiber structure, and a method for producing the same, which can exhibit excellent hygroscopicity, as a material for clothing such as an inner, lining, outer garment, and sports clothing.

[0002]

2. Description of the Related Art Polyethylene terephthalate (hereinafter referred to as PE)
T), thermoplastic synthetic fibers represented by nylon and the like are widely used as clothing materials because of their excellent mechanical properties and many features such as wash and wear properties (W & W properties) and wrinkle resistance. . However, while thermoplastic synthetic fibers have such excellent properties, they have low moisture absorption, so when used for inners, linings, and sports clothing, there is a problem of causing discomfort such as stickiness and stuffiness when sweating. is there. Therefore, in these clothing fields, natural fibers such as cotton are preferred.

[0003] Many proposals have been made to improve such disadvantages of thermoplastic synthetic fibers. For example, it has been proposed that a thermoplastic synthetic fiber contains a polymer containing a carboxylate or a sulfonate, or a compound containing an ether group or a hydroxyl group, as a compound that enhances the hygroscopicity. In addition, as a method for incorporating these hygroscopic compounds, a method of copolymerizing with a thermoplastic polymer, a method of blending and forming a composite fiber, and a post-processing method of reacting the surface after forming a fibrous structure, and the like. Proposed.

[0004] However, despite many proposals, there are a number of problems in the fiber production stage, the fiber structure production stage, and the product use stage, etc., and there are many problems in industrial use. Has not been reached. For example, problems in the fiber production stage include thermal decomposition of the hygroscopic compound itself during melt spinning and yarn breakage during spinning. Problems at the fiber structure manufacturing stage include scouring, alkali reduction, and removal of the hygroscopic compound during dyeing. Further, problems at the stage of using as a product include falling off during dry cleaning and deterioration of color fastness.

[0005] Accordingly, the emergence of thermoplastic synthetic fibers having a moisture absorption comparable to that of natural fibers without impairing the characteristics of the thermoplastic synthetic fibers has been a longing in the art. In recent years, a crosslinked polyacrylic acid-based polymer has been found as a polymer exhibiting high hygroscopicity and water absorbency, and has attracted attention. [For example,
"New development of superabsorbent polymer" (published by Osaka Chemical Marketing Center in 1987)] Polyacrylic acid itself is water-soluble despite its high moisture absorption and water absorption based on carboxyl groups. It is common to crosslink and make water insoluble because of its properties. However, since the crosslinked polyacrylic acid polymer cannot be melted and has a low thermal decomposition temperature of about 200 ° C., it is decomposed at a melt spinning temperature of 270 to 300 ° C. of PET, a general-purpose thermoplastic synthetic fiber, and nylon. Coloration occurs and melt spinning is difficult.

Accordingly, as a method of using a polyacrylic acid-based polymer to improve the hygroscopicity of a thermoplastic synthetic fiber, for example, as disclosed in Japanese Patent Application Laid-Open No. 4-245975, an acrylic acid monomer is coated on the surface of a fiber structure. The method of performing a graft reaction was common. As in the publication,
When the acrylic acid polymer is provided on the fiber surface, a certain degree of hygroscopicity can be improved. However, the fibrous structure obtained by the method has a drawback that the surface of the fiber becomes sticky when absorbing moisture and gives discomfort when worn. In addition, there is a problem that the acrylic acid-based polymer is dropped off by dry cleaning or repeated washing, and the durability of hygroscopicity is impaired.

On the other hand, the only proposal for incorporating a polyacrylic acid-based polymer inside a synthetic fiber is disclosed in JP-A-5-214.
No. 670 proposes a method in which acrylic anhydride is mixed and spun at the time of melt spinning of nylon to form a fiber, and then a carboxyl group is imparted by an alkali treatment. However, in the method disclosed in this publication, acrylic anhydride reacts with amide groups of nylon at the time of melt spinning of nylon, and the melt viscosity of nylon changes with time. . Further, the fiber obtained by the method of this publication is eluted from the fiber by repeated washing because the polyacrylic acid which has become a carboxyl group itself is water-soluble, and eventually loses the intended hygroscopicity. . Furthermore, since the polyacrylic acid component swells at the time of moisture absorption or water absorption, there is a problem that the mechanical strength of the nylon fiber is extremely reduced, and the inherent characteristics of the nylon fiber are lost.

Accordingly, as described above, a thermoplastic synthetic fiber having a hygroscopic property without impairing the inherent characteristics of the synthetic fiber has not yet been obtained.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to overcome the above-mentioned problems of the prior art, to eliminate troubles in the fiber production process and post-processing process, and to achieve high moisture absorption without impairing the intrinsic properties of synthetic fibers. An object of the present invention is to provide a thermoplastic synthetic fiber and a fiber structure exhibiting properties and a method for producing the same.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on the realization of the above-mentioned objects, and as a result, have found that a sheath-core composite comprising a thermoplastic polymer as a sheath component and a specific acrylic acid-based polymer as a core component. In the fiber, a cross-sectional structure in which a part of a core component is exposed on the surface of the conjugate fiber, and further, after forming the conjugate fiber into a fibrous structure, saponifying and cross-linking with an alkali and a cross-linking agent, the above-described conventional technology. Have been solved at once, and it has been found that synthetic fibers having excellent hygroscopicity which can be used industrially can be obtained, and the present invention has been completed.

That is, a first aspect of the present invention is a sheath-core type composite fiber having a thermoplastic polymer as a sheath component and an acrylic acid-based polymer as a core component, wherein the core component comprises an acid anhydride represented by the following general formula: A sheath-core type composite fiber comprising, as a main component, an acrylic acid-based polymer composed of at least one selected, and a cross-sectional structure in which a part of the core component is exposed on the surface of the composite fiber; A second aspect of the present invention is a fibrous structure comprising a sheath-core composite fiber having a thermoplastic polymer as a sheath component and an acrylic acid-based polymer as a core component, wherein the core component comprises an acid anhydride represented by the following general formula. As a main component, a polymer obtained by saponifying and cross-linking at least one selected acrylic acid-based polymer, and a core-core composite fiber having a cross-sectional structure in which a part of the core component is exposed on the surface of the composite fiber In the production of a sheath-core composite fiber structure having a thermoplastic polymer as a sheath component and an acrylic acid-based polymer as a core component, a third aspect of the present invention is to provide the core component with the following general formula: A sheath core comprising, as a main component, an acrylic acid polymer composed of at least one selected from the acid anhydrides shown, and having a cross-sectional structure in which a part of the core component is exposed on the surface of the composite fiber. A method for producing a fibrous structure, which comprises saponifying and cross-linking the core component with an alkali and a cross-linking agent after forming the type composite fiber into a fibrous structure.

[0012]

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Hereinafter, the present invention will be described in detail. In the composite fiber of the present invention, the thermoplastic polymer forming the sheath component is not particularly limited as long as it is a fiber-forming polymer.
For example, linear polyesters represented by PET, polybutylene terephthalate, polyethylene 2,6 naphthalate or copolymers thereof, nylon 6, nylon 66, nylon 610, nylon 612, nylon 1
2. Nylon represented by nylon 4 or a copolymer thereof, or polyolefin represented by polypropylene, polyethylene or the like, or a copolymer thereof is used. In addition, these thermoplastic polymers may contain a third component such as a heat stabilizer, a matting agent, an antistatic agent, a flame retardant, an antibacterial agent, and a deodorant as long as the effects of the present invention are not impaired. .

For general purposes, PET, nylon 6, nylon 66, etc. are used because of their advantages such as dyeability and heat resistance for clothing.
Is used. Further, PET, nylon 6, and nylon 66 are also selected from the viewpoint of imparting a high interfacial adhesiveness between a sheath component and a core component described later. Although these thermoplastic polymers constituting the sheath component generally have poor hygroscopicity, they have a characteristic of maintaining sufficient mechanical strength even when absorbing moisture or absorbing water. Therefore, the fiber of the present invention maintains its mechanical strength even when absorbing moisture or absorbing water.

According to a first aspect of the present invention, the core component of the sheath-core conjugate fiber is mainly composed of an acrylic acid-based polymer containing at least one selected from the acid anhydrides represented by the above general formula. Features. The acid anhydride-containing acrylic acid-based polymer can be obtained by polymerizing monomers such as acrylic acid, methacrylic acid, methyl methacrylate, acrylamide, and maleic anhydride, and then cyclizing. It is also possible to copolymerize an aromatic vinyl monomer such as styrene if necessary. A typical production example of an acid anhydride-containing polymer is described in JP-B-61-49325.
The core component of the conjugate fiber of the present invention disclosed in Japanese Patent Application Laid-Open No. H02-151602 and the like needs to contain the acid anhydride-containing acrylic acid-based polymer as a main component. Is not less than 50%, and it is not always necessary to use this alone. If the object of the present invention is not impaired, other plasticizers, heat stabilizers,
It may contain a thermoplastic polymer.

According to a second aspect of the present invention, there is provided a fibrous structure using the sheath-core composite fiber according to the first aspect of the present invention,
The core component of the sheath-core type composite fiber is characterized in that the core component is a polymer obtained by saponifying and cross-linking an acrylic acid polymer containing at least one selected from the acid anhydrides represented by the above general formula. The saponification and cross-linking of the acid anhydride-containing acrylic acid polymer results in a water-insoluble, hygroscopic acrylic acid polymer. When the acid anhydride-containing acrylic acid polymer is simply saponified, the hygroscopicity becomes high, but the acrylic acid polymer itself dissolves in alkali or water, so that the acrylic acid polymer disappears in the post-processing step, and the object of the present invention is Is not achieved. Therefore, it is necessary that the crosslinking is carried out to such an extent that the saponified acrylic acid polymer is at least dissolved in alkali or water and does not disappear.

Such saponification and crosslinking are carried out by the methods described below. In the conjugate fiber of the present invention, the content of the carboxyl group generated by saponification and crosslinking of the core component in the entire conjugate fiber is preferably 0.2 meq / g or more to achieve the object of the present invention. . The greater the carboxyl group equivalent contained in the fiber, the more the fiber absorbs moisture. Preferred carboxyl group equivalent is 0.4 to
2 meq / g.

The residue of the carboxyl group is not particularly limited, but is preferably an alkali metal salt or an alkaline earth metal salt such as Na, K, Li, Zn, Ca or Ba from the viewpoint of heat resistance, washing resistance and the like. . If the sheath component is the same, the performance of the hygroscopicity appears almost uniquely depending on the carboxyl group equivalent contained in the fiber. For example, when the sheath component is nylon, the carboxyl group equivalent is 0.3 to 0.8.
Shows hygroscopicity comparable to natural fiber cotton at milliequivalents / g.
In the case where PET itself is extremely water-blocking, such as PET, the carboxyl group equivalent is preferably 0.8 to 1.5 meq / g.

The sheath-core type composite fiber of the present invention is characterized in that it has a cross-sectional structure in which a part of the core component is exposed on the surface of the composite fiber. 1 to 6 schematically show the cross-sectional shape of the sheath-core conjugate fiber of the present invention. FIG. 1 is a schematic diagram when the number of core components exposed on the fiber surface is four, and FIG.
FIG. 3 shows an example in the case of eight pieces.

FIG. 4 is an enlarged sectional view of the exposed core component shown in FIGS. FIGS. 5 and 6 show examples in which the cross-sectional shape of the core component is different from FIGS. The number of core components exposed on the fiber surface is not particularly limited, but is preferably a plurality in view of the point symmetry of the fiber cross section. Usually, 2 to 8 pieces are employed. FIG. 7 shows a cross-sectional shape of a conventionally known sheath-core composite fiber for comparison.

The present inventors have previously disclosed in Japanese Patent Laid-Open No.
Although the purpose of the present invention is different from that of the present invention,
To "feasible split fibers" having a cross-sectional shape similar to that of FIG. In such a composite fiber having a special cross-sectional shape,
When the conjugate fiber absorbs water, only the core component, which is partially exposed on the fiber surface, is swelled by the sheath component, and becomes narrower when it loses moisture, as if the gap in the schoolhouse was slightly opened or closed. To transform it to It is conceivable that the sheath-core type composite fiber of the present invention absorbs expansion distortion due to water absorption by this school-like deformation.

The degree of exposure of the exposed portion is represented by the ratio of the circumference occupied by the exposed portion to the entire circumference of the fiber cross section.
In the present invention, this ratio is preferably 20% or less. If the content exceeds 20%, when the core component absorbs or absorbs moisture, the texture of the fibers may be slim, or the color fastness of the fibers may be reduced. The smaller the ratio of the exposed part is, the better,
From the viewpoint of fiber formation, 2% to 15% is employed. More preferably, it is 2% to 10%. In the present invention, since the core component is only slightly exposed on the surface of the fiber, practical properties such as dyeability and texture are obtained from the thermoplastic polymer alone as the sheath component despite being a composite fiber. Another major feature is that it can be handled almost in the same way as fiber.

For comparison, in the case of a conventionally known sheath-core composite fiber as shown in FIG. 7, the core component cannot be alkali-saponified as described later, and the present invention cannot be achieved. In the sheath-core type composite fiber of the present invention, the ratio of the sheath component and the core component is
The weight ratio is preferably 50/50 to 90/10. If the ratio of the core component is less than 10% by weight, even if a polymer having a high moisture absorption is used for the core component, the moisture absorption of the whole fiber is insufficient, and the object of the present invention is not sufficiently exhibited.

If the ratio of the core component exceeds 50% by weight, the mechanical properties and dyeing fastness of the conjugate fiber decrease, and the inherent characteristics of the thermoplastic synthetic fiber decrease. The ratio of the core component to the total cross-sectional area of the cross section of the composite fiber is preferably 20 to 40% by weight. The sheath-core type composite fiber of the present invention or the fiber structure comprising the sheath-core type composite fiber has a moisture absorption of 30 after imparting a carboxyl group by saponification and crosslinking treatment.
It is preferable in terms of practical performance that it has 4% by weight (wt%) or more at 90 ° C. and 90% RH. The reason for this is to provide comfort when wearing clothing. That is, the temperature and humidity in the clothes when the clothes are actually worn, especially in clothes close to the human body, are usually 30 to 36 ° C. and 80% to 100% RH. The purpose of the present invention is to immediately transfer the humidity of the air to the outside air, thereby eliminating the stuffiness of the human body and providing comfort.

To provide this comfort, 30 ° C., 90%
The moisture absorption of the fiber at RH is important. According to the present invention, if the moisture absorption is about 6% wt or more, almost comfort is achieved. More preferably, if the content is 10% by weight or more, comfort similar to cotton, which is a representative of natural fibers, can be obtained.
Furthermore, at the time of wetness corresponding to the time of sweating of the human body, about 20 wt.
It is also a major feature of the present invention that it exhibits a high water absorption of at least%. Preferably, it is 40 wt% or more, more preferably 60 w%.
If it is at least t%, the water absorption will be close to that of cotton.

On the other hand, conventionally, it has been considered that the moisture absorption rate at 20 ° C. and 65% RH is 7 wt%, which is the level of cotton, as a necessary condition for comfort. It is said that there is a large difference between the moisture absorption rates at 65 ° C. and 65% RH and at 30 ° C. and 90% RH as comfort requirements. This difference is preferably about 2 wt% or more, and further 3 wt%.
% Or more is preferable.

[0027] Such moisture absorption characteristics are characteristic of clothing as clothing.
This is a preferable characteristic for exhibiting the shandware property. The fiber structure referred to in the present invention is a fabric, a nonwoven fabric, or the like obtained by knitting and weaving fibers, and the fibers may be long fibers or short fibers. The fiber structure of the present invention has both excellent hygroscopicity and excellent characteristics inherent to thermoplastic synthetic fibers.

The fibrous structure of the present invention does not necessarily need to be composed only of the sheath-core conjugate fiber of the first invention of the present invention. It may be knitted or interwoven with conventional thermoplastic synthetic fibers, natural fibers, chemical fibers, or the like. Less than,
The method for producing the sheath-core composite fiber and the fiber structure of the present invention will be described.

The sheath-core type composite fiber of the present invention can be obtained by disposing the thermoplastic polymer as the sheath component and the acid anhydride-containing acrylic acid-based polymer as the core component using a known composite spinning machine. . More specifically, Japanese Unexamined Patent Application Publication No.
It can be manufactured according to the method for manufacturing a conjugate fiber disclosed in Japanese Patent Publication No. 4 (1994) -107. That is, when the two components merge in the spinneret,
The sheath component is supplied from the horizontal direction to the core component flowing in the vertical direction. The number of sheath components is supplied corresponding to the number of core components exposed on the fiber surface.

The ratio of the core component to the total cross-sectional area of the composite fiber cross section is determined by the supply ratio of each polymer of the sheath component and the core component. The ratio of the peripheral length occupied by the core component exposed on the fiber surface to the total peripheral length of the fiber cross section is determined by the melt viscosity ratio of both components. Specifically, it is achieved by adjusting the melt viscosity at the spinning temperature so that the ratio of the sheath component / core component becomes 1 or more, preferably 1.5 or more.

In the spinning and winding method of the sheath-core type composite fiber of the present invention, the fiber spun from the spinneret can be easily obtained by a conventionally known spinning-drawing method. Also, a spin draw take-up method in which the fiber is spun and stretched continuously without being wound up, and a spin take-up method in which the fiber is spun at a speed of about 5000 m / min or more and wound up without being stretched to obtain a practically usable fiber. It can also be obtained by a method.

In particular, when the glass transition temperature of the acrylic acid polymer as the core component is as high as about 100 ° C. or more, the use of the high-speed spin take-up method does not cut the core component at the time of stretching, and achieves good spinnability. You. The present invention is characterized in that after forming such a sheath-core composite fiber into a fibrous structure, the core component is saponified and cross-linked with an alkali and a cross-linking agent.

That is, the fiber structure is saponified and cross-linked with an alkali and a cross-linking agent after the fiber structure is formed, so that the production and knitting and weaving of the fiber can be performed without any difference from the ordinary thermoplastic synthetic fiber until the fiber structure is manufactured. And so on. The saponification of the acid anhydride-containing acrylic acid-based polymer, which is the core component of the sheath-core composite fiber of the present invention, is achieved by immersing the fiber structure in an alkaline bath by a known method. As the alkali, hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, and alkalis represented by sodium carbonate and the like are used. An aqueous solution or alcohol solution of these alkalis is used. Generally, an immersion treatment may be performed as an aqueous solution. The concentration of the aqueous solution is about 1% ~
40%, preferably 3% to 20%, and the treatment temperature is 50%.
It is desirable to carry out at a temperature of 100C to 100C.

In the present invention, it is necessary that the acid anhydride be crosslinked with saponification. Simply saponifying the acid anhydride almost completely dissolves and disappears in the alkaline bath in which the saponified acrylic acid-based polymer is saponified or in the bath during the subsequent washing with water. Therefore, it is necessary that the polymer is cross-linked between acrylic acid-based polymer molecules in a range that prevents such elution during or before saponification.

The crosslinking agent is not particularly limited as long as it is a compound having a reactivity of at least two. For example,
Ammonia, ethylene diamine, triethylene diamine, amines such as hexamethylene diamine, and ethylene glycol, triethylene glycol, glycerin,
Polyhydric alcohols such as pentaerythritol, polyhydric glycidyls such as glycidyl ether, Zn, Ca,
Metal compounds such as Ba and Mg are used.

The cross-linking of the acid anhydride-containing acrylic acid polymer can be carried out by a heat treatment in a solution containing a cross-linking agent, or by applying a cross-linking agent to the conjugate fiber or the conjugate fiber structure and then heat-treating. Can be implemented. The most preferred treatment method is a method in which the above crosslinking agent is co-present in an alkaline treatment bath for saponifying the acid anhydride-containing acrylic acid-based polymer, and saponification and crosslinking are carried out in the same bath. In this case, since the acid anhydride-containing acrylic acid-based polymer swells due to saponification, there is an advantage that the cross-linking reaction is rapidly and uniformly performed. Therefore, the processing time in this method is about 1 minute to 60 minutes.
Minutes, preferably 1 to 20 minutes.

The saponification and cross-linking treatment of the present invention is closely related to the cross-sectional shape of the sheath-core conjugate fiber of the present invention.
That is, the saponification and cross-linking of the acid anhydride-containing acrylic acid polymer of the core component became possible promptly because the core component had a cross-sectional structure exposed to the surface of the composite fiber. For example, in the case of a conventionally known sheath-core conjugate fiber as disclosed in JP-A-4-108113, that is, a conjugate fiber having a cross-sectional structure in which a core component is completely included by a sheath component, how alkali treatment conditions are adjusted Even so, even saponification of the core component was difficult.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

[0039]

EXAMPLES In the examples, each characteristic was measured by the following measuring methods. (A) Moisture absorption rate The sample was conditioned in a thermo-hygrostat (trade name: PR-2C manufactured by Tabai Espec) for 24 hours at 30 ° C. and 90% RH. The moisture absorption was determined by the following equation.

Moisture absorption (%) = (weight after humidity control−weight at absolute dryness) × 100 / weight at absolute dryness (B) Water absorbency After immersing the sample in water for 30 minutes or more, the household electric washing Dewatered for 5 minutes in the dehydrator of the machine. The water absorption was determined from the weight of the absolutely dried sample and the weight of the sample after dehydration according to the following equation. Water absorption (%) = (weight after water preparation-weight when absolutely dry) x 10
0 / weight at the time of absolute dryness (C) Ratio of fiber cross section occupied by exposed portion of core component to total perimeter The cross section of the conjugate fiber was photographed with an optical microscope, and the total perimeter and the exposed perimeter were measured by actual measurement. .

(D) Strength / Elongation [Dry strength] A sample conditioned at 20 ° C. and 65% RH for 24 hours was used for a TENSILON UT manufactured by Toyo Boldwin Co., Ltd.
Using an M-2-20 tensile tester, the initial length was 20 cm,
It was measured at a pulling speed of 20 cm.

[Wet Strength] The sample was immersed in water for 30 minutes or more, and immediately measured with a tensile tester. (E) Equivalent carboxyl group in the fiber The content of the metal component in the fiber or the fibrous structure was quantified by plasma emission analysis and calculated.

For example, when the carboxyl residue is Na,
The sodium content and the carboxyl group equivalent are calculated by the following equation. Carboxyl group content (m equivalent / g) = Na content (%) × 10/23 [Adjustment of acid anhydride-containing acrylic acid polymer]
According to the method described in Example 1 of JP-A-1-49325, an acid anhydride content of 20% by weight (hereinafter abbreviated as polymer A) and 40% by weight (hereinafter, An acid anhydride-containing acrylic acid polymer (abbreviated as polymer B) was obtained. Polymer A and polymer B were both thermoplastic and had a melt viscosity at 290 ° C. of 400 poise and 600 poise, respectively.

[0044]

Example 1 As a sheath component, P having an intrinsic viscosity of 0.62 (measured at a polymer concentration of 1% by weight in O-chlorophenol)
ET (melt viscosity at 290 ° C. 1300 poise) was used. Acid anhydride-containing acrylic acid-based polymers A and B shown in Table 1 were used as core components. By changing the discharge ratio of the sheath component and the core component by a known twin screw extruder,
No. 1 in Table 1. 1 to 8 composite fibers were obtained.

In spinning, the sheath component flows from the horizontal direction toward the center of the core component in six normal lines with respect to the vertical flow of the core component, whereby the sheath-core composite having the cross-sectional shape shown in FIG. 3 is formed. Fiber was obtained. (Details of the spinning method are described in
According to Example 1 of Japanese Patent No. 26814. ) Extruded at a spinning temperature of 290 ° C. and a discharge rate of 17.8 g / min using a spout having a hole diameter of 0.25 mmφ, L / D = 2 and 24 holes, winding at 1000 m / min, winding at 90 ° C. .
It was drawn twice to obtain a drawn yarn of 50d / 24f. During the spinning, the test was successfully performed without any problem. After knitting the obtained sheath-core type composite fiber, an aqueous solution containing 12% by weight of NaOH and 20% by weight of pentaerythritol at 90 ° C.
The sample was immersed for 5 minutes to perform saponification and cross-linking. The weight loss rate by saponification and crosslinking treatment was 4% by weight. PE
Although only T alone was similarly fiberized, the weight reduction rate in the same alkaline bath was also 4% by weight, so that the dissolution of the acrylic acid polymer in the alkaline bath did not substantially occur. ing.

Table 1 shows the mechanical strength of the obtained sheath-core composite fiber and the moisture absorption properties after saponification and crosslinking. As is clear from Table 1, the knitted fabric of the present invention exhibits good hygroscopicity and water absorbency without a decrease in mechanical strength due to moisture absorption or wetting. Also,
The texture and the color fastness were not inferior to those obtained from conventional PET fibers.

[0047]

[Comparative Example 1] Here, a case where no cross-linking treatment is performed will be described. No. 1 of the first embodiment. After the sheath-core type composite fiber of No. 6 was knitted, the same alkali treatment as in Example 1 was performed in an alkali bath different only in that glycerin was not contained. The weight reduction rate by the alkali treatment was 20% by weight, and the composite fiber was divided into six pieces of fine fibers. The moisture absorption of this fiber was 0.4% at 65% RH and 1.0% at 90% RH, indicating only the known PET levels.

[0048]

Comparative Example 2 PET used in Example 1 was used as a sheath component, polymer A was used as a core component, and the ratio of the sheath component / core component was 80.
/ 20, and the cross-sectional shape of the fiber is as shown in FIG.
A sheath-core type composite fiber in which the core component disclosed in Japanese Patent No. 108113 was completely included in the sheath component was obtained.

After knitting the obtained sheath-core type composite fiber,
The alkali treatment was performed in the same alkali treatment bath as in Example 1. Although the weight loss by the treatment was 4% by weight, the core component Polymer A was not saponified at all, and the moisture absorption of the knitted fabric was 65%.
% RH: 0.4%, 90% RH: 1.0%, water absorption: 4%
% And only known PET levels.

[0050]

Example 2 Nylon 66 (2 in relative viscosity 2.6 (measured in 98% sulfuric acid, polymer concentration 1% by weight)) as a sheath component
A sheath-core type composite fiber similar to that of Example 1 was obtained by using the polymer A as the core component and varying the sheath-core ratio as shown in Table 2 using a melt viscosity at 90 ° C. of 900 poise). All of the spinning properties were good.

The sheath-core type composite fiber is passed through 118 fibers / in,
A plain weave with a weft density of 89 weaves / in was used. This woven fabric is
The immersion treatment was performed at 90 ° C. for 20 minutes in an alkaline aqueous solution containing 15% by weight of OH and 20% by weight of sorbite. The weight loss by the alkali treatment was only 1% by weight. Table 2 shows the moisture absorption properties of the obtained sheath-core type composite fiber and woven fabric.

As apparent from Table 2, the fiber of the present invention can be used without impairing the mechanical strength inherent in nylon 66.
It had the same hygroscopicity as cotton of natural fiber.

[0053]

Comparative Example 3 Nylon 66 and polymer B used in Example 2 were mixed and spun at 290 ° C. in a 90/10 weight ratio according to the method of Example 1 in JP-A-5-214670. Approximately 1 hour after the start of extrusion
It rose to 00 poise, making extrusion difficult.

Further, the bare fiber was treated with a 5% by weight aqueous solution of NaOH at 90 ° C. for 20 minutes.
Most of the polymer B was dissolved in the alkali treatment bath, and the moisture absorption was only 4% at 65% RH and 8% at 90% RH, which was only the level of known nylon 66.

[0055]

[Table 1]

[0056]

[Table 2]

[0057]

The sheath-core conjugate fiber of the present invention and the fiber structure using the same retain mechanical properties such as strength, wash and wear properties, dyeing fastness, etc., which are inherent properties of thermoplastic fibers. In addition, there is provided a moisture-absorbing fiber exhibiting excellent moisture absorption and having a high commercial value. Moreover, the production method of the present invention
The fiber production step and the fiber structure production step are characterized in that they can be carried out without any problems similarly to conventional thermoplastic synthetic fibers.

The sheath-core type composite fiber of the present invention is used for a wide range of uses such as innerwear, lining, outer garment, sports clothing, etc. by subjecting it to false twisting, scouring and dyeing in the same manner as conventional thermoplastic fibers. It is possible. It is also possible to mix and knit with conventionally known synthetic fibers such as polyester and nylon, and natural and chemical fibers such as cotton, wool, hemp, rayon and cupra.

Furthermore, the sheath-core type composite fiber of the present invention has a good hygroscopic property even when mixed with other fibers such as cotton, wool, hemp, and can be used for a wide range of applications. .

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically illustrating a cross-sectional shape of a sheath-core conjugate fiber of the present invention when the number of core components exposed on the fiber surface is four.

FIG. 2 is a cross-sectional view schematically showing a cross-sectional shape of the sheath-core conjugate fiber of the present invention when the number of core components exposed on the fiber surface is six.

FIG. 3 is a cross-sectional view schematically showing a cross-sectional shape of the sheath-core conjugate fiber of the present invention when the number of core components exposed on the fiber surface is eight.

FIG. 4 is an enlarged cross-sectional view of a portion of the core component shown in FIGS.

FIG. 5 is a cross-sectional view schematically showing a cross-sectional shape of the sheath-core conjugate fiber of the present invention when the shape of the core component is different from those in FIGS.

FIG. 6 is a cross-sectional view schematically showing a cross-sectional shape of the sheath-core conjugate fiber of the present invention when the shape of the core component is different from those in FIGS.

FIG. 7 is a cross-sectional view schematically showing a cross-sectional shape of a conventionally known sheath-core composite fiber.

[Explanation of Signs] 1 core component 2 sheath component 3 part exposed on the surface

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-4-126814 (JP, A) JP-A-4-108113 (JP, A) JP-A-2-151602 (JP, A) JP-A-63- 40211 (JP, A) JP-A-5-272015 (JP, A) JP-B 61-49325 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) D01F 8/00-8 / 18

Claims (3)

(57) [Claims] 1. A sheath-core composite fiber comprising a thermoplastic polymer as a sheath component and an acrylic acid-based polymer as a core component, wherein the core component comprises at least one selected from acid anhydrides represented by the following general formula: A sheath-core type composite fiber comprising an acrylic acid-based polymer as a main component and having a cross-sectional structure in which a part of the core component is exposed on the surface of the composite fiber. Embedded image 2. A fibrous structure comprising a sheath-core type composite fiber having a thermoplastic polymer as a sheath component and an acrylic acid-based polymer as a core component, wherein the core component is selected from acid anhydrides represented by the following general formula: A fiber comprising a sheath-core composite fiber having a cross-sectional structure in which a main component is a polymer obtained by saponifying and cross-linking an acrylic acid polymer containing at least one kind, and a part of the core component is exposed on the surface of the composite fiber. Structure. Embedded image 3. In the production of a sheath-core composite fiber structure having a thermoplastic polymer as a sheath component and an acrylic acid-based polymer as a core component, the core component is selected from acid anhydrides represented by the following general formula: A fiber-structured sheath-core conjugate fiber comprising at least one acrylic acid-based polymer as a main component, and having a cross-sectional structure in which a part of the core component is exposed on the surface of the conjugate fiber. And then saponifying and crosslinking the core component with an alkali and a crosslinking agent. Embedded image