AU2016351997B2 - Core-sheath composite cross-section fiber having excellent moisture absorbency and wrinkle prevention - Google Patents

Abstract

A core-sheath composite cross-section fiber characterized in that the core section polymer is a thermoplastic polymer, the sheath-section polymer is a polyamide having a dicarboxylic acid unit which has a sebacic acid unit as a main component, the boiling-water shrinkage ratio is 6.0-12.0%, and the stress per unit fineness during 3% elongation in a fiber tensile test is 0.60 cN/dtex or more. A core-sheath composite cross-section fiber is provided having excellent moisture-absorbing capability and wrinkling prevention, and in which the moisture-absorbing capability is maintained even when washed.

Description

TITLE OF THE INVENTION: CORE-SHEATH COMPOSITE CROSS-SECTION FIBER HAVING EXCELLENT MOISTURE ABSORBENCY AND WRINKLE PREVENTION TECHNICAL FIELD

[0001]

The present invention relates to a core-sheath composite

cross-section fiber excellent in moisture absorbency and

wrinkle prevention.

BACKGROUND ART

[0002]

Synthetic fibers made from thermoplastic resins such as

polyamides and polyesters are widely used in clothing

applications, industrialapplications and the like because they

are excellentin strength, chemicalresistance, heat resistance

and the like.

[0003]

In particular, polyamide fibers are excellentin moisture

absorbing and releasing performance in addition to

characteristics such as distinctive softness, high tensile

strength, coloring property at dyeing, and highheat resistance,

and are widely used in underwear, sportswear, and the like.

Polyamide fibers, however, are still insufficient in moisture absorbing and releasing performance as compared with natural fibers such as cotton, and have problems such as stuffy and sticky feeling. Thus, polyamide fibers are inferior to natural fibers in terms of wearing comfort.

[0004]

From such a background, synthetic fibers that exhibit

excellent moisture absorbing and releasing performance for

preventing stuffy and sticky feeling, and that give wearing

comfort comparable to that ofnaturalfibers are demandedmainly

for underwear and sportswear applications.

[0005]

In view of this, Patent Document 1discloses a core-sheath

composite cross-section fiber made of a core section and a

sheath section, the core section being not exposed to the fiber

surface, in which the core section is made from a polyether block

amide copolymer having polycaproamide as a hard segment, the

sheath section is made from polycaproamide, and the area ratio

of the core section to the sheath section in the fiber

cross-section is 3/1 to 1/5.

[0006]

Moreover, Patent Document 2 discloses a core-sheath

composite cross-section fiber excellent in moisture absorbing

and releasing performance, the core-sheath composite

cross-section fiber having a core section made from a

thermoplastic polymer and a sheath section made from a fiber-forming polyamide, in which the thermoplastic polymer forming the core section contains a polyether ester amide copolymer as a main component, and the percentage of the core section is 5 to 50% by weight of the totalweight of the composite fiber.

[0007]

Moreover, Patent Document 3 discloses a core-sheath

composite cross-section fiber excellent in antistatic

performance, water absorption performance, and cool contact

feeling, the core-sheath composite cross-section fiber having

a core section made from a polyether block amide copolymer and

a sheath section made from a fiber-forming polymer such as a

polyamide or a polyester, in which the core section is exposed

at an exposure angle in the range of 5° to 90°. The core-sheath

composite cross-section fibers of Patent Documents 1 to 3 are

increasingly used as woven or knitted fabrics for underwear and

sports applications.

PRIOR ART DOCUMENTS PATENT DOCUMENTS

[0008]

Patent Document 1: International Publication No.

2014/10709

Patent Document 2: Japanese Patent Laid-open Publication

No. 6-136618

Patent Document 3: International Publication No.

2008/123586

[0009]

Although the core-sheath composite cross-section fibers

of Patent Documents 1 to 3 are excellent in moisture absorbing

and releasing performance due to the high moisture-absorbing

capability of the core component polymer, the core-sheath

composite cross-section fibers are easilydeformedandwrinkled

in the dyeing step because they are made from flexible polymers

having high shrinkage characteristics. Moreover, such

phenomenon easily occurs also during washing. Furthermore,

the core-sheath composite cross-section fibers also have

problems that the core section is deteriorated due to repeated

actualuse, and the moisture-absorbing capability decreases due

to repeated use.

[0010]

The presentinvention deals with the problems ofthe prior

techniques and seeks to provide a core-sheath composite

cross-section fiber excellent in moisture absorbing and

releasing performance and wrinkle prevention. The present

invention also aims to provide a core-sheath composite

cross-section fiber that maintains the moisture-absorbing

capability even after being washed.

[0011]

Accordingly, the present invention provides:

[0012]

(1) A core-sheath composite cross-section fiber,

comprising: apolyether ester amide copolymer as a core polymer;

and a polyamide having a dicarboxylic acid unit having, as a

main component, a sebacic acid unit as a sheath polymer, the

core-sheath composite cross-section fiber having a AMR of 5.0%

or more, a AMR retention rate after 20 times of washing of 90%

or more and 100% or less, a boiling-water shrinkage ratio of

6.0 to 12.0%, anda stress perunit fineness during3% elongation

in a fiber tensile test of 0.60 cN/dtex or more.

[0013]

(2) The core-sheath composite cross-section fiber

according to (1), wherein a sheath section has an a-crystal

orientation parameter of 2.10 to 2.70.

[0014]

(3) The core-sheath composite cross-section fiber

according to (1) or (2), having a retention rate of stress per

unit fineness during 3% elongation in a fiber tensile test of

60% or more before and after boiling water treatment.

[0015]

(4) A fabric including the core-sheath composite

cross-section fiber according to any one of (1) to (3) in at

least a part thereof.

[0016]

(5) Atextile product including the core-sheath composite

cross-section fiber according to any one of (1) to (3) in at

least a part thereof.

EFFECTS OF THE INVENTION

[0017]

According to the present invention, it is possible to

provide a core-sheath composite cross-section fiber that is

excellent in moisture-absorbing capability and wrinkle

prevention, and that maintains the moisture-absorbing

capability even after being washed.

EMBODIMENTS OF THE INVENTION

[0018]

The core-sheath composite cross-section fiber of the

present invention contains a polyamide having a dicarboxylic

acid unit having, as a main component, a sebacic acid unit as

a sheath polymer, and a thermoplastic polymer having high

moisture-absorbing capability as a core polymer.

[0019]

The polyamide having a dicarboxylic acid unit having, as a main component, a sebacic acid unit in the sheath section is a polymer made from a so-called high molecular weight material in which a hydrocarbon is linked to a main chain via an amide bond, and specific examples of the polyamide include polypentamethylene sebacamide, polyhexamethylene sebacamide, and copolymers thereof. From the viewpoint of economy, relatively easy yarn making, and excellent dyeability and mechanical characteristics, such a polyamide is preferably a polyamide mainly including polyhexamethylene sebacamide.

[0020]

The polyamide having a dicarboxylic acid unit having, as

a main component, a sebacic acid unit in the sheath section may

contain various additives, such as a matting agent, a flame

retardant, an antioxidant, an ultravioletabsorber, aninfrared

absorber, a crystal nucleating agent, a fluorescent whitening

agent, an antistatic agent, a hygroscopic polymer, and carbon

in the form of a copolymer or a mixture as needed at a total

additive content of 0.001 to 10% by weight.

[0021]

The thermoplasticpolymer havinghighmoisture-absorbing

capability in the core section refers to a polymer having a AMR

as measured in a pellet form of 10% or more, which is a polyether

ester amide copolymer. Also described are polyvinyl alcohol,

and a cellulose thermoplasticpolymer. Apolyether ester amide

copolymer is advantageous from the viewpoint of high thermal stability, high compatibility with the polyamide in the sheath section, and excellent peeling resistance.

[0022]

The "AMR" as used herein means a value obtained in the

following manner. About 1 to 2 g of pellets are weighed in a

weighing bottle, the pellets are dried at 110°C for 2 hours and

the weight (WO) is measured, and then the pellets are held at

20°C and a relative humidity of 65% for 24 hours and the weight

(W65) is measured. Then, the pellets are held at 300C and a

relative humidity of 90% for 24 hours and the weight (W90) is

measured. The AMR is calculated according to the following

formulae.

[0023]

MR65 (%) = [(W65 - W0)/W0] x 100

MR90 (%) = [(W90 - WO)/WO] x 100

AMR (%) = MR90 - MR65

[0024]

A polyether ester amide copolymer is a block copolymer

having an ether bond, an ester bond, and an amide bond in one

molecular chain. More specifically, a polyether ester amide

copolymer is ablock copolymer obtainedby the polycondensation

reaction of at least one polyamide component (A) selected from

lactams, aminocarboxylic acids, and salts of diamines and

dicarboxylic acids, with a polyether ester component (B) formed of a dicarboxylic acid and a poly(alkylene oxide) glycol.

[0025]

Examples of the polyamide component (A) include lactams

such as c-caprolactam, dodecanolactam, and undecanolactam,

(-aminocarboxylic acids such as aminocaproic acid,

11-aminoundecanoic acid, and 12-aminododecanoic acid, and

nylon salts of diamines and dicarboxylic acids, which are

precursors of polyhexamethylene adipamide, polyhexamethylene

sebacamide, polyhexamethylene dodecanamide and the like. A

preferable polyamide component is E-caprolactam.

[0026]

The polyether ester component (B) is formed of a

dicarboxylic acid having 4 to 20 carbon atoms and a

poly(alkylene oxide) glycol. Examples of the dicarboxylic

acid having 4 to 20 carbon atoms include aliphatic dicarboxylic

acids suchas succinicacid, glutaricacid, adipicacid, pimelic

acid, suberic acid, sebacic acid, and dodecanoic acid, aromatic

dicarboxylicacids suchas terephthalicacid, isophthalicacid,

and 2,6-naphthalenedicarboxylic acid, and alicyclic

dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid.

One of them or a mixture of two or more of them can be used.

Preferable dicarboxylic acids are adipic acid, sebacic acid,

dodecanoic acid, terephthalic acid, and isophthalic acid.

Examples of the poly(alkylene oxide) glycol include

polyethylene glycol, poly(1,2- and 1,3-propylene oxide) glycol, poly(tetramethylene oxide) glycol, and poly(hexamethylene oxide) glycol. Polyethylene glycol having particularly high moisture-absorbing capability is preferable.

[0027]

The number average molecular weight of the poly(alkylene

oxide) glycol is preferably from 300 to 10,000, more preferably

from 500 to 5,000. A molecular weight of 300 or more is

preferable because the poly(alkylene oxide) glycol hardly

scatters to the outside of the system during the

polycondensation reaction, and a fiber having stable

moisture-absorbing capability is obtained. Meanwhile, a

molecular weight of 10,000 or less is preferable because a

homogeneous block copolymer is obtained and the yarn making

property is stabilized.

[0028]

The composition rate of the polyether ester component (B)

is preferably from 20 to 80% in terms of the molar ratio. A

composition rate of 20% or more is preferable because high

moisture absorbency can be obtained. A composition rate of 80%

or less is preferable because high color fastness and washing

durability can be obtained.

[0029]

As such a polyether ester amide copolymer, "MH1657" and

"MV1074" manufactured by ARKEMA K.K. and the like are

commercially available.

[00301

The core-sheath composite cross-section fiber of the

present invention is required to have a boiling-water shrinkage

ratio of 6.0 to 12.0%. If the boiling-water shrinkage ratio

exceeds 12.0%, the fiber is easily deformed and wrinkled in the

dyeing step. If the boiling-water shrinkage ratio is less than

6.0%, although the fiber is excellent in wrinkle prevention,

there are cases where the operability in the yarn making step

is deteriorated or the quality is deteriorated. A

boiling-water shrinkage ratio within the above-mentioned range

gives a fiber excellent in wrinkle prevention. The

boiling-water shrinkage ratio is preferably from 6.0 to 10.0%.

[0031]

The core-sheath composite cross-section fiber of the

present invention is required to have a stress per unit fineness

during 3% elongation in a fiber tensile test of 0.60 cN/dtex

or more. The stress during 3% elongation in a fiber tensile

test is obtained by subjecting a sample to a tensile test under

the constant rate extension conditions shown in JIS L1013

(Chemicalfiber filament yarn test method, 2010), and obtaining

the strength at 3% elongation of the sample in a tensile

strength-elongation curve for the determination of the stress.

This strength is divided by the fineness of the fiber to obtain

the stress per unit fineness during 3% elongation in a fiber

tensile test.

[00321

The stress per unit fineness during 3% elongation in a

fiber tensile test corresponds to a rising portion of the

tensile strength-elongation curve, and is a parameter that

shows the rigidity of the fiber. The larger the value is (the

steeper the rise of the tensile strength-elongation curve is),

the more rigid the fiber is. That is, a fiber having a stress

per unit fineness during 3% elongation in a fiber tensile test

of 0.60 cN/dtex or more is suppressed in deformation in the

dyeingstep, andis excellentinwrinkleprevention. The stress

per unit fineness during 3% elongation in a fiber tensile test

is preferably 0.70 cN/dtex or more.

[0033]

In the core-sheath composite cross-section fiber of the

present invention, the polyamide in the sheath section

preferably has an a-crystal orientation parameter of 2.10 to

2.70, more preferably from 2.20 to 2.60. It is generally known

that an a-crystal is a stable crystal form, and is formed when

high stress is applied. When the polyamide in the sheath

section has an a-crystal orientation parameter within the

above-mentioned range, the polyamide in the sheath section is

preferentially stretched between a stretching roller and a

take-up roller from the spinning to the take-up, so that

sufficient a-crystals as a stable crystal form can be made

present. As a result, at the time of melt spinning, the stretching force concentrates on the polyamide in the sheath section, and the thermoplastic polymer having high moisture-absorbing capabilityin the core section is suppressed in crystallization. As a result, the moisture-absorbing capability of the core-sheath composite fiber can be further increased, and at the same time, the rigidity of the sheath section is increased, so that the tensile stress of the core-sheath composite fiber can be further increased.

[0034]

When the polyamide in the sheath section has an a-crystal

orientation parameter of 2.10 or more, the crystallization of

the polyamide in the sheath section proceeds, and the

core-sheath composite cross-section fiber is improved in the

tensile stress during 3% elongation, and moreover, the

crystallization of the thermoplastic polymer having high

moisture-absorbing capability in the core section does not

proceed, and the core-sheath composite cross-section fiber is

also improved in the moisture absorbing and releasing

performance. On the other hand, when the polyamide has an

u-crystal orientation parameter of 2.70 or less, the

crystallization of the polyamide in the sheath section does not

proceed, and yarn breakage and generation of fluffin the higher

order processing steps can be suppressed, so that productivity

is improved.

[0035]

The core-sheath composite cross-section fiber of the

present invention preferably has a retention rate of stress per

unit fineness during 3% elongation in a fiber tensile test of

60% or more before and after boiling water treatment. When the

retention rate of stress per unit fineness is within the

above-mentioned range, changes in the fiber structure and

crystal orientation degree in the dyeing step are small, the

shrinkage of the fiber is suppressed, and the rigidity of the

fiber is also easilymaintained, so that it is possible to obtain

a fiber excellent in wrinkle prevention. In a fiber subjected

to boiling water treatment, the fiber structure is changed

mainly in an amorphous part, hydrogen bonds between amide bonds

in the amorphous part are broken, the mobility of the molecular

chain is improved, and the orientation degree is lowered. As

a result of the changes in the fiber structure in the amorphous

part and the orientation degree, the fiber shrinks and the

rigidity of the fiber decreases. Therefore, suppressing the

shrinkage of the fiber as much as possible and maintaining the

rigidity of the fiber as much as possible before and after the

boiling water treatment suppress the deformation of the fiber

and improve the wrinkle prevention in the dyeing step.

Furthermore, deformation of the fiber is suppressed and the

wrinkle prevention is improved also during washing.

[00361

The thermoplasticpolymer havinghighmoisture-absorbing capability in the core section, which constitutes the core-sheath composite cross-section fiber of the present invention, is a polymer having low crystallinity and poor rigidity. Therefore, the polymer comes to have high shrinkage characteristics and is easily increased in flexibility due to boiling water treatment. Therefore, in the core-sheath composite cross-section fiber of the present invention, a polyamide including polyhexamethylene sebacamide having relatively high rigidity and low shrinkability is selected from polyamides as the sheath polymer to impart rigidity to the sheath section, and further the fiber is made under specific yarn making conditions (such as the heat setting temperature and the lubrication position) as will be described later to suppress the shrinkage characteristics andimprove the rigidity, so that the wrinkle prevention and moisture-absorbing capability are improved. The retention rate of stress per unit fineness is more preferably 70% or more.

[0037]

The core-sheath composite cross-section fiber of the

present invention preferably has a tensile strength of 3.0

cN/dtex or more, more preferably from 3.5 to 5.0 cN/dtex. A

tensile strength within the above-mentioned range makes it

possible to provide a product excellent in durability in

practical use.

[0038]

The core-sheath composite cross-section fiber of the

present invention preferably has a degree of elongation of 35%

or more, more preferably from 40 to 65%. A degree of elongation

within the above-mentioned range improves the passability of

the fiber in the higher order steps such as weaving, knitting,

and false twisting.

[0039]

In order to give high wearing comfort, the core-sheath

composite cross-section fiber of the present invention is

required to have a function of adjusting the humidity inside

the clothes. As an indicator of humidity adjustment, AMR is

used. The AMR is represented by the difference in moisture

absorptivity between that at the temperature and humidity

inside the clothes typified by 30°C x 90% RH in work on light

to medium duty or light to medium exercise, and that at the

outside temperature and humidity typified by 20°C x 65% RH. The

larger the AMRis, the higher the moisture-absorbing capability

is, and a larger AMR corresponds to higher wearing comfort.

[0040]

The core-sheath composite cross-section fiber of the

present invention has a AMR of 5.0% or more. The AMR is

preferably 7.0% or more, more preferably 10.0% or more. A AMR

within the above-mentioned range makes it possible to suppress

stuffy and sticky feeling during wearing, and to provide

clothing excellent in comfort.

[0041]

The core-sheath composite cross-section fiber of the

present invention has a AMR retention rate after 20 times of

washing of 90% or more and 100% or less. The AMR retention rate

is preferably 95% or more and 100% or less. A AMR retention

rate within the above-mentioned range provides washing

durability against actual use, so that it is possible to provide

clothing that maintains excellent comfort. Furthermore, a

core-sheath composite cross-section fiber having a AMR of 5.0%

or more and a AMR retention rate after 20 times of washing of

90% or more can provide clothing excellent in comfort that has

washing durability against actual use.

[0042]

The core-sheath composite cross-section fiber of the

present invention may be either of a filament and a staple

depending on the application. The total fineness, the number

of filaments (in the case of a long fiber), and the length and

number of crimps (in the case of a short fiber) are also not

particularly limited, but the total fineness is preferably from

5 to 235 dtex and the number of filaments is preferably from

1 to 144 in consideration of the use as a long fiber material

for clothing.

[0043]

The core-sheath composite cross-section fiber of the

present invention can be obtained by techniques such as melt spinning and composite spinning. Examples of the spinning technique are as follows. For example, a polyamide (sheath section) and a thermoplastic polymer having high moisture-absorbing capability (core section) are separately melted, and metered and transported with a gear pump, a composite flow is directly formed and discharged from a melt spinneret, and the obtainedyarns are cooled toroom temperature with a yarn cooling device such as a chimney, lubricated and bundled with a lubrication device, entangled with a first fluid entangling nozzle device, and stretched according to the ratio of the circumferential speed between a take-up roller and a stretching roller. Then, the yarns are heat-set with the stretching roller, and wound up with a winder (winding device)

[0044]

In order to obtain the core-sheath composite

cross-section fiber of the present invention, it is preferable

to select a polyamide having an appropriate molecular structure,

and to adopt a suitable take-up speed, a suitable lubrication

position, and a suitable heat setting temperature after

stretching. These will be described in detail below.

[0045]

As described above, the polyamide used in the sheath

section of the core-sheath composite cross-section fiber of the

present invention is preferably a polyamide having a

dicarboxylic acid unit having, as a main component, a sebacic acid unit, that is, a polymer made from a so-called high molecular weight material in which a hydrocarbon is linked to a main chain via an amide bond. Selecting a polyamide having a high capability of forming a hydrogen bond between amide bonds for the sheath section provides a core-sheath composite cross-section fiber in which a hydrogen bond between amide bonds in an amorphous part is hardly broken even at dyeing and drying at a high temperature exceeding 100C, and which is reduced in changes in the fiber structure of the sheath section and excellent in wrinkle prevention of the fabric at dyeing. The

"capability of forming a hydrogen bond between amide bonds" as

used herein is determined by the degree of freedom of the main

chain of the polyamide molecule, that is, the number of

methylene groups per one amide bond. Therefore, selecting such

a polyamide for the sheath section provides a core-sheath

composite cross-section fiber excellent in wrinkle prevention

of the fabric at dyeing.

[0046]

The polyamide used in the core-sheath composite

cross-section fiber of the present invention may contain

various additives, such as a matting agent, a flame retardant,

an antioxidant, an ultraviolet absorber, an infrared absorber,

a crystal nucleating agent, a fluorescent whitening agent, an

antistatic agent, a hygroscopic polymer, and carbon in the form

of a copolymer or a mixture as needed at a total additive content of 0.001 to 10% by weight.

[0047]

The polyamide chip used in the core-sheath composite

cross-section fiber of the present invention preferably has a

sulfuric acid relative viscosity of 2.30 to 3.30. A sulfuric

acid relative viscosity within the above-mentioned range makes

it possible to appropriately stretch the polyamide in the sheath

section. When the sulfuric acid relative viscosity of the

polyamide in the sheath section is 2.30 or more, a practically

usable fiber strength and elongation is obtained. On the other

hand, when the sulfuricacid relative viscosityis 3.30 or less,

since the polyamide has a melt viscosity suitable for spinning,

the stringing property during melt spinning is improved, and

a fiber can be stably produced with no yarn breakage. The

sulfuric acid relative viscosity is more preferably from 2.50

to 3.10.

[0048]

The proportion of the core section in the core-sheath

composite cross-section fiber of the present invention is

preferably from 20 parts by weight to 80 parts by weight to 100

parts by weight of the composite fiber. The proportion of the

core section is more preferably from 30 parts by weight to 70

parts by weight. A proportion of the core section within the

above-mentioned range makes it possible to appropriately

stretch the polyamide in the sheath section. In addition, such a proportion gives high color fastness and moisture-absorbing capability.

[00491

The temperature in the melting step is preferably from

250 to 290°C for the case of a polyhexamethylene sebacamide chip

as the polyamide having a dicarboxylic acid unit having, as a

main component, a sebacic acid unit used in the sheath section,

and is preferably from 220 to 2600C for the case of "MH1657"

manufactured by ARKEMA K.K. as the thermoplastic polymer having

high moisture-absorbing capability used in the core section.

[0050]

In the take-up step, the take-up speed is preferably from

2500 to 3400 m/min. A take-up speed within the above-mentioned

range makes the orientation crystallization of the core polymer

moderately proceed andmoderately suppress the crystallization

of the core polymer, so that the stress per unit fineness during

3% elongation and the boiling-water shrinkage ratio can be

controlled within preferable ranges, and the fiber is excellent

in moisture-absorbing capability and wrinkle prevention, and

canmaintain the moisture-absorbing capability even after being

washed. A take-up speed exceeding 3400 m/min makes the

orientation crystallization of the polyamide in the sheath

section proceed during stretching with spinning tension, but

the a-crystal orientation parameter of the polyamide in the

sheath section decreases, the rigidity of the sheath polymer decreases, and the fiber may be easily wrinkled due to a low mechanical stretch ratio. A take-up speed less than 2500 m/min provides a high mechanical stretch ratio, but due to insufficient stretching by the spinning tension, the x-crystal orientation parameter of the polyamide in the sheath section decreases, the rigidity of the sheath polymer decreases, and the fiber may be easily wrinkled. In addition, orientation crystallization of the core polymer proceeds, and the moisture-absorbing capability decreases. The take-up speed is more preferably from 2700 to 3200 m/min.

[0051]

In the lubricating step, the lubrication position is

preferably at a position from 800 to 1500 mm from the lower

surface of the spinneret. The polymer discharged from the

spinneret is blown with cooling air from a cooling device to

be solidified into yarns, and the yarns are stretched in the

section from the solidification position to the lubrication

position by spinning tension with accompanying flow, and then

mechanically stretched between the take-up roller and the

stretching roller. As for the core-sheath composite

cross-section fiber of the present invention, it is important

to increase the mechanical stretch ratio in order to promote

the orientation crystallization of the sheath polymer to

increase the rigidity, and to decrease the spinning tension in

order to suppress the orientation crystallization of the core polymer to improve the moisture-absorbing capability. In other words, setting the lubrication position at a position within the above-mentioned range makes it possible to increase the stress per unit fineness during 3% elongation in a fiber tensile test, and to provide a fiber excellent in wrinkle prevention and moisture-absorbing capability. If the lubrication position is at a position less than 800 mm from the lower surface of the spinneret, the yarns are largely bent between the spinneret and the lubrication position, and an oil is supplied to the yarns in a state where the yarns are not sufficiently solidified, so that yarn breakage frequently occurs and the operability may be deteriorated. On the other hand, if the lubrication position is at a position more than

1500 mm from the lower surface of the spinneret, not only the

orientation crystallization of the core polymer proceeds due

to the high spinning tension to decrease the moisture-absorbing

capability, but also the rigidity of the sheath polymer

decreases, and the fiber may be easily wrinkled due to a low

mechanical stretch ratio. The lubrication position is more

preferably at a position from 1000 to 1300 mm from the lower

surface of the spinneret.

[0052]

In the stretching step, the temperature of the heat

setting after stretching is preferably from 165 to 180C. The

fiber oriented and crystallized by stretching between the rollers is further crystallized by the high-temperature heat setting treatment on a heating roller, so that the fiber structure is stabilized. The boiling-water shrinkage ratio depends on the shrinkage of the amorphous part of the fiber, that is, the proportion of the amorphous part. The "heat setting temperature" as used herein means the set temperature of the heating roller.

[00531

The polymer having high moisture-absorbing capability in

the core section, which constitutes the core-sheath composite

cross-section fiber of the present invention, has high

amorphous properties and high shrinkability. Therefore, a

fiber made from only the single polymer is expected to have a

large boiling-water shrinkage ratio. In view of the above, the

core-sheath composite cross-section fiber of the present

invention contains, as a sheath polymer, a polyamide having a

dicarboxylic acid unit having, as a main component, a sebacic

acid unit, which has relatively high rigidity and low

shrinkability among polyamides, to impart rigidity to the

sheath section and suppress the shrinkability of the core

section. Moreover, heat setting at a temperature within the

above-mentioned range after the stretching can stabilize the

fiber structure, control the boiling-water shrinkage ratio

within the range of 6.0 to 12.0%, and provide a fiber excellent

in wrinkle prevention. Ifthe heat setting temperature is lower than 165C, the crystallization of the polyamide in the sheath section is insufficient, the fiber structure is not stabilized, and the fiber may be easily wrinkled. On the other hand, if the heat setting temperature exceeds 180°C, although a fiber excellent in wrinkle prevention can be obtained, contamination of the heating roller with a decomposition product of a spinning oil or the like is promoted, deterioration of the quality and breakage of the spun yarns occur frequently, the operability is deteriorated, and the fiber may be deteriorated in the process passability through higher order processing steps.

The heat setting temperature is more preferably from 170 to

1750C.

[00541

Since the core-sheath composite cross-section fiber of

the present invention is excellent in moisture-absorbing

capability, it is preferably used in clothing items, and the

fabricformcan be selected fromawoven fabric, a knitted fabric,

a nonwoven fabric and the like according to the purpose. As

described above, the larger the AMR is, the higher the

moisture-absorbing capability is, and a larger AMR corresponds

to higher wearing comfort. Accordingly, a fabricincluding the

core-sheath composite fiber of the presentinvention in at least

a part thereof, which has a mixing ratio of the composite fiber

of the present invention adjusted so that the AMR will be 5.0%

or more, can provide clothing excellent in comfort. The clothingitemsmaybe various textile products suchas underwear and sportswear.

EXAMPLES

[00551

Hereinafter, the presentinvention willbe describedmore

specifically by way of examples. Measurement methods and the

like of the characteristic values in the examples are as

follows.

[00561

(1) Sulfuric acid relative viscosity

A polyamide chip sample (1 g) was dissolved in 100 ml of

sulfuric acid having a concentration of 98% by weight, and the

flow time (Ti) of the resulting solution at 25°C was measured

with an Ostwald viscometer. Then, the flow time (T2) of

sulfuric acid having a concentration of 98% by weight alone was

measured. The ratio of Ti to T2, that is, T1/T2, was taken as

the sulfuric acid relative viscosity.

[0057]

(2) Ortho-chlorophenol relative viscosity (OCP relative

viscosity)

A polyether ester amide copolymer chip sample (1 g) was

dissolved in 100 ml of ortho-chlorophenol, and the flow time

(Ti) of the resulting solution at 250C was measured with an

Ostwald viscometer. Then, the flow time (T2) of ortho-chlorophenol alone was measured. The ratio of Ti to T2, that is, T1/T2, was taken as the ortho-chlorophenol relative viscosity.

[00581

(3) Fineness

A fiber sample was set on a sizing reel having a perimeter

of 1.125 m, and rotated 200 times to make a looped skein. The

skein was dried (105 ± 2C x 60 minutes) with a hot air dryer,

and the skein weight was measured with a scaling balance. The

fineness based on corrected mass was calculated from the value

obtainedbymultiplying the skeinweightby the officialregain.

[00591

(4) Strength and degree of elongation

A fiber sample was measured with "TENSILON" (registered

trademark) UCT-100 manufactured by ORIENTEC CORPORATION under

the constant rate extension conditions shown in JIS L1013

(Chemical fiber filament yarn test method, 2010). The degree

of elongation was determined from the elongation of a point

showing the maximum strength in a tensile strength-elongation

curve. The strength was a value obtained by dividing the

maximum strength by the fineness based on corrected mass. The

measurement was carried out 10 times, and the average values

were taken as the strength and degree of elongation.

[00601

(5) Stress per unit fineness during 3% elongation (stress during 3% elongation)

A tensile test of a fiber sample was carried out by the

method described in the item (4), and the strength at the point

where the sample showed 3% elongation in the tensile

strength-elongation curve was determined and taken as the

stress during 3% elongation. The measurement was carried out

10 times, and the average value was taken as the stress during

3% elongation.

[0061]

(6) a-Crystal orientation parameter

A fiber sample was measured by laser Raman spectroscopy,

and a ratio between the intensity ratio of Raman bands derived

from a nylon a-crystal observed at around 1120 cm in parallel

polarization ((11120) parallel) and the intensity ratio of

Raman bands in vertical polarization ((11120) vertical) was

obtained as aparameter for the evaluation oforientation degree.

Further, the scattering intensity under each polarization

condition (parallel/vertical) was normalized on the basis of

the Raman bandintensity of the CH deformation band (around1440

cm') having small anisotropy of orientation.

[0062]

a-Crystal orientation parameter = (11120/11440)

parallel/(I1120/Il440) vertical

The fiber sample for orientationmeasurement was embedded

in a resin (bisphenol type epoxy resin, cured for 24 hours), and then sectioned with a microtome. The section had a thickness of 2.0 pm. The section sample was cut slightly inclined from the fiber axis so that the cut face would have an elliptical shape, and the portion where the thickness of the minor axis of the ellipse was constant was selected and measured.

The measurement was performed in the microscopic mode, and the

spot diameter of the laser at the sample position was 1 pm. The

orientation of the centers of the core and sheath layers was

analyzed, and the orientation was measured under polarization

conditions. The orientation degree was evaluated based on the

ratio between the Raman band intensities obtained under a

parallel condition in which the polarization direction

coincided with the fiber axis and a vertical condition in which

the polarization direction was orthogonal to the fiber axis.

The measurement was performed 3 times for eachmeasurement point,

and the average thereofwasused. Detailedconditions are shown

below.

[00631

Laser Raman spectroscopy

Apparatus: T-64000 (Jobin Yvon/Atago Bussan Co., Ltd.)

Conditions: measurement mode; micro Raman

Objective lens: x100

Beam diameter: 1 pm

Light source: Ar+ laser/514.5 nm

Laser power: 50 mW

Diffraction grating: Single 600 gr/mm

Slit: 100 pm

Detector: CCD/Jobin Yvon 1024 x 256

[0064]

(7) Boiling-water shrinkage ratio

The boiling-water shrinkage ratio was measured according

to JIS L1013: 2010 8.18.1 (method B).

[0065]

(8) Production of woven fabric

The core-sheath composite cross-section fiber of the

present invention was used as the warp and the weft. At a warp

density of188 yarns/2.54 cm and a weft density of155 yarns/2.54

cm, the fiber was woven into a flat structure with a water jet

loom.

[0066]

According to a conventional method, the resulting gray

fabric was scoured with an open soaper in a solution containing

2 g of caustic soda (NaOH) per liter, dried in a cylinder dryer

at 1200C, and then preset at 1700C. Then, the gray fabric was

heated to 120°C at a rate of 2.0°C/min in a pressure-resistant

drum type dyeing machine, and dyed at a set temperature of 120°C

for 60 minutes. After the dyeing, the fabric was washed with

running water for 20 minutes, and dehydrated and dried to give

a woven fabric having a warp density of 200 yarns/2.54 cm and

a weft density of 160 yarns/2.54 cm.

[00671

(9) Evaluation of wrinkle prevention

The woven fabric obtained in the item (8) was subjected

to the method described in paragraph 9 of JIS L1059-2 (Testing

methods for crease recovery of textiles - Part 2: Evaluation

of the wrinkle recovery of fabrics (wrinkle method), 2009), and

the wrinkle prevention was judged as Grade 5 (the most smooth

appearance) to Grade 1 (the most wrinkly appearance). When the

fabric was judged as Grade 3 or higher, the fabric was judged

as being excellent in wrinkle prevention.

[0068]

(10) AMR

The woven fabric obtained in the item (8) (about 1 to 2

g) was weighed in a weighing bottle, held at 110°C for 2 hours

to dry, and the weight (WO) was measured. Then, a target

substance was held at 20°C and a relative humidity of 65% for

24 hours, and then the weight (W65) was measured. Then, the

target substance was held at 300C and a relative humidity of

90% for 24 hours, and then the weight (W90) was measured. Then,

the AMR was calculated according to the following formulae.

[00691

MR65 = [(W65 - WO)/WO] x 100%..... (1)

MR90 = [(W90 - WO)/WO] x 100%..... (2)

AMR = MR90 - MR65 ........... (3)

[0070 ]

(11) AMR after washing

The woven fabric obtained in the item (8) was repeatedly

subjected to 20 times of washing by the method described in No.

103 in the attached table 1 of JIS L0217 (1995), and then the

AMR described in the item (10) was calculated.

[0071]

When the AMRwas 5.0% ormore, thewoven fabricwas judged

to give high wearing comfort.

[0072]

(12) AMR retention rate after washing

The AMR retention rate after washing was calculated

according to the following formula as an index of change of AMR

before and after washing.

[0073]

(AMR after washing treatment - AMR before washing

treatment)/AMR before washing treatment x 100

When the AMR retention rate was 90% or more, the fabric

was judged as having washing durability.

[0074]

(13) Process passability through higher order processing

steps

Using the core-sheath composite cross-section fiber of

the present invention, 10 pieces (1000 m/piece) of plain weave

fabrics were woven with a water jet loom at a loom rotation speed

of 750 rpm and a weft length of 1620 mm. The number of stoppage of the loomdue to yarnbreakage during the weavingwas evaluated.

When the number of yarn breakage was 2 times or less, the fiber

was judged to be good in process passability.

[0075]

(Example 1)

A polyether ester amide copolymer (MH1657 manufactured

by ARKEMA K.K. (chip AMR: 18.9)) having an ortho-chlorophenol

relative viscosity of 1.69 as a core section, and nylon 610

having a sulfuric acid relative viscosity of 2.72 as a sheath

section were melted at 2700C, and spun from a concentric

core-sheath composite spinneret so that the core/sheath ratio

(parts by weight) would be 50/50.

[0076]

In this process, the rotation speed of the gear pump was

selected so that the obtained core-sheath composite yarn would

have a total fineness of 56 dtex, and the polymers were each

discharged at 22 g/min. Then, the yarns were cooled and

solidified with a yarn cooling device, and an anhydrous oil was

supplied with a lubrication device from a lubrication position

at aposition of1000mmfrom the lower surface of the spinneret.

Then, the yarns were entangled with a first fluid entangling

nozzle device, stretched at a circumferentialspeed ofa take-up

roller as a first roll of 2800 m/min and a stretch ratio between

the take-up roller and a stretching roller of 1.50 times, and

heat-set at a set temperature of the stretching roller of 170°C.

Then, the yarns were wound up at a winding speed of 4000 m/min

to give a core-sheath composite cross-section fiber of 56

dtex/24 filaments.

[0077]

For the obtained core-sheath composite cross-section

fiber, the fineness, strength, degree ofelongation, stress per

unit fineness during 3% elongation, boiling-water shrinkage

ratio, retention rate of stress per unit fineness during 3%

elongation before and after boiling water treatment, and

a-crystal orientation parameter were measured. The obtained

woven fabric was evaluated for wrinkle prevention, AMR, AMR

after washing, and AMR retention rate after washing. The

results are shown in Table 1.

[0078]

(Example 2)

Acore-sheath composite cross-section fiber of56 dtex/24

filaments was obtained in the same manner as in Example 1 except

that the heat setting temperature of the heating roller was

1800C.

[0079]

For the obtained core-sheath composite cross-section

fiber, the fineness, strength, degree ofelongation, stress per

unit fineness during 3% elongation, boiling-water shrinkage

ratio, retention rate of stress during 3% elongation before and

after boiling water treatment, and a-crystal orientation parameter were measured. The obtained woven fabric was evaluated for wrinkle prevention, AMR, AMR after washing, and

AMR retention rate after washing. The results are shown in

Table 1.

[00801

(Example 3)

Acore-sheath composite cross-section fiber of56 dtex/24

filaments was obtained in the same manner as in Example 1 except

that the heat setting temperature of the heating roller was

1650C.

[0081]

For the obtained core-sheath composite cross-section

fiber, the fineness, strength, degree ofelongation, stress per

unit fineness during 3% elongation, boiling-water shrinkage

ratio, retention rate of stress during 3% elongation before and

after boiling water treatment, and a-crystal orientation

parameter were measured. The obtained woven fabric was

evaluated for wrinkle prevention, AMR, AMR after washing, and

AMR retention rate after washing. The results are shown in

Table 1.

[0082]

(Example 4)

Acore-sheath composite cross-section fiber of56 dtex/24

filaments was obtained in the same manner as in Example 1 except

that the lubrication position was at a position of 1500 mm from the lower surface of the spinneret, and the yarns were wound up at a winding speed of 3900 m/min.

[00831

For the obtained core-sheath composite cross-section

fiber, the fineness, strength, degree ofelongation, stress per

unit fineness during 3% elongation, boiling-water shrinkage

ratio, retention rate of stress during 3% elongation before and

after boiling water treatment, and a-crystal orientation

parameter were measured. The obtained woven fabric was

evaluated for wrinkle prevention, AMR, AMR after washing, and

AMR retention rate after washing. The results are shown in

Table 1.

[0084]

(Example 5)

Acore-sheath composite cross-section fiber of56 dtex/24

filaments was obtained in the same manner as in Example 1 except

that the lubrication position was at a position of 800 mm from

the lower surface of the spinneret.

[00851

For the obtained core-sheath composite cross-section

fiber, the fineness, strength, degree ofelongation, stress per

unit fineness during 3% elongation, boiling-water shrinkage

ratio, retention rate of stress during 3% elongation before and

after boiling water treatment, and a-crystal orientation

parameter were measured. The obtained woven fabric was evaluated for wrinkle prevention, AMR, AMR after washing, and

AMR retention rate after washing. The results are shown in

Table 1.

[00861

(Example 6)

Acore-sheath composite cross-section fiber of56 dtex/24

filaments was obtained in the same manner as in Example 1 except

that the lubrication position was at a position of 1500 mm from

the lower surface of the spinneret, the stretch ratio between

the take-up roller and the stretching roller was 1.45 times,

and the yarns were wound up at a winding speed of 3900 m/min.

[0087]

For the obtained core-sheath composite cross-section

fiber, the fineness, strength, degree ofelongation, stress per

unit fineness during 3% elongation, boiling-water shrinkage

ratio, retention rate of stress during 3% elongation before and

after boiling water treatment, and c-crystal orientation

parameter were measured. The obtained woven fabric was

evaluated for wrinkle prevention, AMR, AMR after washing, and

AMR retention rate after washing. The results are shown in

Table 1.

[00881

(Example 7)

Acore-sheath composite cross-section fiber of56 dtex/24

filaments was obtained in the same manner as in Example 1 except that the lubrication position was at a position of 800 mm from the lower surface of the spinneret, the stretch ratio between the take-up roller and the stretching roller was 1.55 times, and the yarns were wound up at a winding speed of 4100 m/min.

[00891

For the obtained core-sheath composite cross-section

fiber, the fineness, strength, degree ofelongation, stress per

unit fineness during 3% elongation, boiling-water shrinkage

ratio, retention rate of stress during 3% elongation before and

after boiling water treatment, and a-crystal orientation

parameter were measured. The obtained woven fabric was

evaluated for wrinkle prevention, AMR, AMR after washing, and

AMR retention rate after washing. The results are shown in

Table 1.

[00901

(Example 8)

Acore-sheath composite cross-section fiber of56 dtex/24

filaments was obtained in the same manner as in Example 1 except

that the circumferential speed of the take-up roller as a first

roll was 2500 m/min, the stretch ratio between the take-up

roller and the stretching roller was 1.65 times, and the yarns

were wound up at a winding speed of 3900 m/min.

[0091]

For the obtained core-sheath composite cross-section

fiber, the fineness, strength, degree ofelongation, stress per unit fineness during 3% elongation, boiling-water shrinkage ratio, retention rate of stress during 3% elongation before and after boiling water treatment, and a-crystal orientation parameter were measured. The obtained woven fabric was evaluated for wrinkle prevention, AMR, AMR after washing, and

AMR retention rate after washing. The results are shown in

Table 1.

[0092]

(Example 9)

Acore-sheath composite cross-section fiber of56 dtex/24

filaments was obtained in the same manner as in Example 1 except

that the circumferential speed of the take-up roller as a first

roll was 3400 m/min, the stretch ratio between the take-up

roller and the stretching roller was 1.20 times, and the yarns

were wound up at a winding speed of 3900 m/min.

[0093]

For the obtained core-sheath composite cross-section

fiber, the fineness, strength, degree ofelongation, stress per

unit fineness during 3% elongation, boiling-water shrinkage

ratio, retention rate of stress during 3% elongation before and

after boiling water treatment, and a-crystal orientation

parameter were measured. The obtained woven fabric was

evaluated for wrinkle prevention, AMR, AMR after washing, and

AMR retention rate after washing. The results are shown in

Table 1.

[00941

(Comparative Example 1)

Acore-sheath composite cross-section fiber of56 dtex/24

filaments was obtained in the same manner as in Example 1 except

that the heat setting temperature of the heating roller was

1900C.

[0095]

For the obtained core-sheath composite cross-section

fiber, the fineness, strength, degree ofelongation, stress per

unit fineness during 3% elongation, boiling-water shrinkage

ratio, retention rate of stress during 3% elongation before and

after boiling water treatment, and a-crystal orientation

parameter were measured. The obtained woven fabric was

evaluated for wrinkle prevention, AMR, AMR after washing, and

AMR retention rate after washing. The results are shown in

Table 2.

[0096]

At this level in which the heat setting temperature of

the heating roller was high, the fiber was excellent in

moisture-absorbing capability and wrinkle prevention, and

maintained moisture-absorbing capability even after being

washed. However, contamination of the heating roller with a

decomposition product of a spinning oilor the like was promoted,

yarn breakage in the higher order processing steps occurred

frequently, and the fiber was poor in the process passability.

[00971

(Comparative Example 2)

Acore-sheath composite cross-section fiber of56 dtex/24

filaments was obtained in the same manner as in Example 1 except

that the set temperature of the stretching roller was 150°C.

[0098]

For the obtained core-sheath composite cross-section

fiber, the fineness, strength, degree ofelongation, stress per

unit fineness during 3% elongation, boiling-water shrinkage

ratio, retention rate of stress during 3% elongation before and

after boiling water treatment, and a-crystal orientation

parameter were measured. The obtained woven fabric was

evaluated for wrinkle prevention, AMR, AMR after washing, and

AMR retention rate after washing. The results are shown in

Table 2.

[0099]

At this level in which the heat setting temperature of

the heating roller was low, the balance of shrinkage

characteristics between nylon 610 in the sheath section and the

polyether ester amide copolymer in the core section was

disrupted, the boiling-water shrinkage ratio was as high as

15.0%, and the woven fabric was wrinkled.

[0100]

(Comparative Example 3)

Acore-sheath composite cross-section fiber of56 dtex/24 filaments was obtained in the same manner as in Example 1 except that the lubrication position was at a position of 1800 mm from the lower surface of the spinneret, the stretch ratio between the take-up roller and the stretching roller was 1.30 times, and the yarns were wound up at a winding speed of 3500 m/min.

[0101]

For the obtained core-sheath composite cross-section

fiber, the fineness, strength, degree ofelongation, stress per

unit fineness during 3% elongation, boiling-water shrinkage

ratio, retention rate of stress during 3% elongation before and

after boiling water treatment, and a-crystal orientation

parameter were measured. The obtained woven fabric was

evaluated for wrinkle prevention, AMR, AMR after washing, and

AMR retention rate after washing. The results are shown in

Table 2.

[0102]

At this level in which the distance between the lower

surface of the spinneret and the lubrication position was long,

the rigidity of nylon 610 in the sheath section was low, the

balance of shrinkage characteristics between nylon 610 in the

sheath section and the polyether ester amide copolymer in the

core section was disrupted, the stress per unit fineness during

3% elongation was as low as 0.58 cN/dtex, and the woven fabric

was wrinkled.

[0103]

(Comparative Example 4)

Acore-sheath composite cross-section fiber of56 dtex/24

filaments was obtained in the same manner as in Example 1 except

that the circumferential speed of the take-up roller as a first

roll was 2200 m/min, the stretch ratio between the take-up

roller and the stretching roller was 1.80 times, and the yarns

were wound up at a winding speed of 3800 m/min.

[0104]

For the obtained core-sheath composite cross-section

fiber, the fineness, strength, degree ofelongation, stress per

unit fineness during 3% elongation, boiling-water shrinkage

ratio, retention rate of stress during 3% elongation before and

after boiling water treatment, and a-crystal orientation

parameter were measured. The obtained woven fabric was

evaluated for wrinkle prevention, AMR, AMR after washing, and

AMR retention rate after washing. The results are shown in

Table 2.

[0105]

At this level in which the take-up speed was low, the

rigidity of nylon 610 in the sheath section was low, the balance

of shrinkage characteristics between nylon 610 in the sheath

section and the polyether ester amide copolymer in the core

section was disrupted, the boiling-water shrinkage ratio was

12.3%, and the woven fabric was wrinkled.

[0106]

(Comparative Example 5)

Acore-sheath composite cross-section fiber of56 dtex/24

filaments was obtained in the same manner as in Example 1 except

that the circumferential speed of the take-up roller as a first

roll was 3700 m/min, the stretch ratio between the take-up

roller and the stretching roller was 1.05 times, and the yarns

were wound up at a winding speed of 3700 m/min.

[0107]

For the obtained core-sheath composite cross-section

fiber, the fineness, strength, degree ofelongation, stress per

unit fineness during 3% elongation, boiling-water shrinkage

ratio, retention rate of stress during 3% elongation before and

after boiling water treatment, and a-crystal orientation

parameter were measured. The obtained woven fabric was

evaluated for wrinkle prevention, AMR, AMR after washing, and

AMR retention rate after washing. The results are shown in

Table 2.

[0108]

At this level in which the take-up speed was high, the

rigidity of nylon 610 in the sheath section was low, the balance

of shrinkage characteristics between nylon 610 in the sheath

section and the polyether ester amide copolymer in the core

section was disrupted, the stress per unit fineness during 3%

elongation was as low as 0.54 cN/dtex, the woven fabric was

wrinkled, yarn breakage in the higher order processing steps occurred frequently, and the fiber was poor in the process passability.

[0109]

(Comparative Example 6)

Acore-sheath composite cross-section fiber of56 dtex/24

filaments was obtained in the same manner as in Example 1 except

that nylon 6 having a sulfuric acid relative viscosity of 2.40

was used in the sheath section, and the heat setting temperature

of the heating roller was 150°C.

[0110]

For the obtained core-sheath composite cross-section

fiber, the fineness, strength, degree ofelongation, stress per

unit fineness during 3% elongation, boiling-water shrinkage

ratio, retention rate of stress during 3% elongation before and

after boiling water treatment, and a-crystal orientation

parameter were measured. The obtained woven fabric was

evaluated for wrinkle prevention, AMR, AMR after washing, and

AMR retention rate after washing. The results are shown in

Table 2.

[0111]

At this levelin which the polyamide in the sheath section

was nylon 6, the rigidity of nylon 6 in the sheath section was

low, the balance of shrinkage characteristics between nylon 6

in the sheath section and the polyether ester amide copolymer

in the core section was disrupted, the stress per unit fineness during 3% elongation was as low as 0.53 cN/dtex, and the woven fabric was wrinkled.

N--H--i -- SII s - . 1a -. -1.

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Fo o IF OFI

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[0114]

The reference in this specification to any prior

publication (or information derived from it), ortoanymatter

which is known, is not, and should not be taken as an

acknowledgment or admission or any form of suggestion that that

prior publication (or information derived from it) or known

matter forms part of the common general knowledge in the field

of endeavour to which this specification relates.

[0115]

Throughout this specification and the claims which follow,

unless the context requires otherwise, the word "comprise", and

variations such as "comprises" and "comprising", will be

understood to imply the inclusion of a stated integer or step

or group of integers or steps but not the exclusion of any other

integer or step or group of integers or steps.

48A

Claims (5)

1. Acore-sheathcomposite cross-section fiber, comprising:

a polyether ester amide copolymer as a core polymer; and a

polyamide having a dicarboxylic acid unit having, as a main

component, a sebacic acid unit as a sheath polymer, the

core-sheath composite cross-section fiber having a AMR of 5.0%

or more, a AMR retention rate after 20 times of washing of 90%

or more and 100% or less, a boiling-water shrinkage ratio of

6.0 to 12.0%, and astress perunit fineness during3% elongation

in a fiber tensile test of 0.60 cN/dtex or more.

2. The core-sheath composite cross-section fiber according

to claim 1, wherein a sheath section has an ax-crystal

orientation parameter of 2.10 to 2.70.

3. The core-sheath composite cross-section fiber according

to claim 1 or 2, having a retention rate of stress per unit

fineness during 3% elongation in a fiber tensile test of 60%

or more before and after boiling water treatment.

4. A fabric comprising the core-sheath composite

cross-section fiber according to any one of claims 1 to 3 in

at least a part thereof.

5. A textile product comprising the core-sheath composite

cross-section fiber according to any one of claims 1 to 3 in

at least a part thereof.