JP2002088586A - Highly stretchable conjugated polyester fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly stretchable conjugated polyester fiber by solving a conventional problem on crimping ability under a tension in a fabric, and to provide a fabric having excellent elongation recovery, softness, stretchability and good appearance quality, using the fiber. SOLUTION: This highly stretchable conjugated polyester fiber having 1-3 dtex single filament size is obtained by sticking two kinds of polyester polymers along the fiber length direction so as to form a side-by-side shape. Both of the two kinds of the polyester polymers are polyesters consisting essentially of a polytrimethylene terephthalate, having a difference ΔIV of intrinsic viscosities of both components, satisfying the formula 1.20>ΔIV>0.6, and the intrinsic viscosity of the lower viscosity polymer satisfying the formula IV (L)>=0.6. The conjugate fiber is characterized by <=2% coefficient value (U%) of variation of sizes of a multifilament yarn, >=120% elastic elongation after the heat treatment, and >=90% elastic recovery.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-stretch polyester conjugate fiber which is excellent in softness and excellent in quality and can give an appropriate stretch property to a fabric with excellent crimp development ability.

[0002]

2. Description of the Related Art Polyester has various excellent properties such as mechanical properties, and is widely used not only for clothing. In addition, various methods have been adopted in order to impart a stretch property to the polyester-based fabric by a recent stretch boom.

For example, there is a method in which polyurethane elastic fibers are mixed in a woven fabric to impart stretchability. However, when polyurethane-based fibers are mixed, the texture is hard as an inherent property of polyurethane, the texture and drape property of the fabric are reduced, and the disperse dye for polyester is hardly dyed, which causes a problem of contamination. This not only complicates the dyeing process, such as strengthening the reduction washing, but also makes it difficult to dye a desired color.

There is also a method of imparting stretchability to a woven fabric by subjecting a polyester fiber to false twisting and using a fiber exhibiting twisting / untwisting torque. However, there is a problem that this torque tends to transfer to the grain on the surface of the fabric and tends to be a defect of the fabric. For this reason,
Torque balance is achieved by heat treatment or S / Z twist to balance the stretchability and the defects caused by the crimping. However, there has been a problem that the stretchability is generally too low.

On the other hand, as a method using no polyurethane fiber or false twisted yarn, various types of latently crimp-expressing polyester fibers using a side-by-side composite have been proposed. Latent crimp-expressing polyester fiber refers to a polyester fiber that exhibits crimp by heat treatment or has the ability to develop finer crimp than before heat treatment, and is distinguished from ordinary false twisted yarn. Things.

[0006] For example, Japanese Patent Publication No.
Japanese Patent No. 308271 discloses a side-by-side composite yarn of polyethylene terephthalate (hereinafter abbreviated as PET) having an intrinsic viscosity difference or an intrinsic viscosity difference, and Japanese Patent Application Laid-Open No. 5-295634 discloses a side-by-side of homo PET and copolymer PET having higher shrinkage. A composite yarn is described. If such a latently crimp-expressing polyester fiber is used, it is possible to obtain a certain degree of stretchability, but the stretchability of the woven fabric becomes insufficient, and it is difficult to obtain a satisfactory stretchable woven fabric. was there. This is because the side-by-side composite yarn as described above has a low crimp development ability under the constraint of the fabric, or the crimp is easily set by external force. The side-by-side composite yarn does not use the stretch property due to the expansion and contraction of the fiber itself like the polyurethane fiber, but uses the expansion and contraction of the three-dimensional coil caused by the difference in the shrinkage ratio between the composite polymers for the stretch property.
For this reason, for example, when heat treatment is performed under a woven fabric constraint in which the shrinkage of the polymer is restricted, the heat fixation is performed as it is, and the shrinkage ability is further lost.

Further, since such a composite crimped yarn develops a crimp after being subjected to boiling water treatment, it is used for a purpose such as kimono or the like which develops a grain, but at this time, there is a large variation in fineness in the longitudinal direction of the fiber. Thus, there is a problem that the grain is not uniformly developed and the quality is deteriorated, and that the single fiber fineness is 4 dtex or more, which is generally lacking in softness.

[0008]

DISCLOSURE OF THE INVENTION The present invention has improved yarn forming properties such as spinning and drawing, and has improved crimp development ability under the constraint of woven fabric, which is a problem with conventional polyester-based latently crimpable fibers. It is another object of the present invention to provide a highly stretchable polyester fiber capable of obtaining a high-quality fabric excellent in stretchability and softness.

[0009]

Means for Solving the Problems To solve the above-mentioned problems, the polyester latently crimpable fiber of the present invention mainly has the following constitution. That is, in a conjugate fiber in which two types of polyester-based polymers are bonded in a side-by-side type, each of the two types of polyester polymers is a polyester mainly composed of polytrimethylene terephthalate. And a monofilament fineness of 1 dtex or more and 3 dtex, wherein the multifilament yarn has a fineness variation rate U% value of 2% or less, a stretch rate of 120% or more, and a stretch modulus of 90% or more.
The following highly stretchable polyester-based composite fibers are provided. However,
When the intrinsic viscosity of the polymer on the high viscosity side is IV (H) and the intrinsic viscosity of the polymer on the low viscosity side is IV (L), and the intrinsic viscosity difference between the two polymers is ΔIV, 1.20>ΔIV> 0.6 IV (L) ≧ 0.6 Stretching elongation (%) = [(L1-L0) / L0] × 100 Stretching elasticity (%) = [(L1-L2) / (L1-L0)] ×
100 L0: 15 minutes of boiling water treatment and 17 of dry heat treatment with a processing load of 3.53 × 10 ⁻³ cN / dtex applied to a 560 mm long scab.
Perform 0 ° C x 5 minutes, then remove the processing load, and 1.76 x ^10-3 cN
Latch length when the initial load of / dtex is suspended for 30 seconds L1: Latch length when the initial load is removed and constant load of 0.09 cN / dtex is suspended for 30 seconds L2: Initial load 1.76 again 2 minutes after the constant load is removed × 10 ^-3 cN /
Length of skewer when dtex is hung for 30 seconds

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The highly stretchable polyester composite fiber of the present invention is a composite fiber in which two types of polyester polymers are bonded in a side-by-side type along the fiber length direction. Each type of polyester polymer is a polyester mainly composed of polytrimethylene terephthalate, and is a highly stretchable polyester-based composite fiber characterized in that the intrinsic viscosity difference between the two components satisfies the following formula. Here, the intrinsic viscosity of the polymer on the high viscosity side is IV (H), and the intrinsic viscosity of the polymer on the low viscosity side is IV (H).
Assuming that the intrinsic viscosity difference between the two polymers is ΔIV when (L) is satisfied, 1.20>ΔIV> 0.6 IV (L) ≧ 0.6. The two types of polymers having different viscosities are bonded in a side-by-side type along the fiber length direction. By bonding polymers having different viscosities, stress is concentrated on the high viscosity side during spinning and drawing. , The internal distortion differs between the two components. Therefore, the high-viscosity side largely shrinks due to the difference between the elastic recovery rate after the stretching and the difference in the heat shrinkage rate in the heat treatment step of the fabric, causing distortion within the single fiber to take a form of a three-dimensional coil crimp. It can be said that the diameter of the three-dimensional coil and the number of coils per unit fiber length are determined by the difference in shrinkage (including the difference in elastic recovery rate) between the high shrinkage component and the low shrinkage component. And the number of coils per unit fiber length increases.

A coil crimp required as a stretch material has a small coil diameter, a large number of coils per unit fiber length (excellent elongation characteristics, good appearance), and good coil set resistance (expansion and contraction). The set amount of the coil according to the number of times is small and the stretch retention is excellent), and the hysteresis loss at the time of recovery from the extension of the coil is small (excellent resilience and good fit). By satisfying all of these requirements and having the properties of polyester, such as moderate tension, drapability, and high color fastness, a stretch material excellent in total balance can be obtained.

The present inventors have conducted intensive studies to satisfy the above-mentioned properties without impairing the properties of the polyester. As a result, polytrimethylene terephthalate (hereinafter abbreviated as PTT) is mainly used as the high shrinkage component and the low shrinkage component. It was found that a polyester was used. PTT fibers have mechanical properties and chemical properties equivalent to those of typical polyester fibers such as PET and polybutylene terephthalate (hereinafter abbreviated as PBT) fibers, and are extremely excellent in elongation recovery. This is because in the PTT crystal structure, the methylene chain of the alkylene glycol moiety has a Gauche-Gauche structure (the molecular chain is bent at 90 degrees), and further, the interaction between benzene rings (stacking, parallel).
Due to the low binding point density and high flexibility, the rotation of the methylene group allows the molecular chain to easily elongate.
Think to recover. Thus, both the high shrinkage component (high viscosity component) and the low shrinkage component (low viscosity component)
By adjusting the melting point and the glass transition point to T, the stress can be concentrated on the higher viscosity component in the spinning step, and the difference in shrinkage can be increased. In addition, both components are PTT
By doing so, the Young's modulus of the fiber can be reduced as seen in the strength-elongation curve after the boiling water treatment shown in FIG.
A crimped yarn having a softer and more excellent elasticity can be obtained.

The viscosity referred to in the present invention is the intrinsic viscosity (I
V) is a value measured by dissolving a sample in orthochlorophenol.

The composite ratio of the two components is determined in terms of the spinning property and the dimensional homogeneity of the coil in the fiber length direction.
Low shrinkage component = 75: 25 to 35:65 (% by weight) is preferable, and 65/35 to 45/55 is more preferable.

Here, the PTT of the present invention is a polyester obtained by using terephthalic acid as a main acid component and 1,3-propanediol as a main glycol component. However, it may contain a copolymer component capable of forming another ester bond at a ratio of 20 mol%, more preferably 10 mol% or less. As the copolymerizable compound, for example, isophthalic acid, succinic acid, cyclohexanedicarboxylic acid, adipic acid, dimeric acid, sebacic acid, 5-
Dicarboxylic acids such as sodium sulfoisophthalic acid,
Examples thereof include, but are not limited to, diols such as ethylene glycol, diethylene glycol, butanediol, neopentyl glycol, cyclohexanedimethanol, polyethylene glycol, and polypropylene glycol. Also, if necessary,
Titanium dioxide as a matting agent, silica or alumina fine particles as a lubricant, hindered phenol derivatives, coloring pigments and the like as antioxidants may be added.

The highly stretchable PTT conjugate fiber of the present invention is characterized in that the stretch ratio is 120% or more and the stretch modulus is 90% or more.

Expansion and contraction rate (%) = [(L1-L0) / L
0] × 100 Stretch elastic modulus (%) = [(L1-L2) / (L1-L0)] ×
100 L0: 15 minutes of boiling water treatment and 17 of dry heat treatment with a processing load of 3.53 × 10 ⁻³ cN / dtex applied to a 560 mm long scab.
Perform 0 ° C x 5 minutes, then remove the processing load, and 1.76 x ^10-3 cN
Latch length when the initial load of / dtex is suspended for 30 seconds L1: Latch length when the initial load is removed and constant load of 0.09cN / dtex is suspended for 30 seconds L2: Initial load 1.76 again 2 minutes after the constant load is removed × 10 ^-3 cN /
The length of the ridge when the dtex is hung for 30 seconds The higher the stretch ratio, the higher the crimp development ability, and if it is 120% or more, the desired elongation characteristics of the present invention can be provided. The higher the stretch ratio is, the higher the elongation of the fabric is.
Above, more preferably 140% or more.

Incidentally, a PET-based composite yarn having an intrinsic viscosity difference as described in JP-B-44-2504 or JP-A-Hei 5-29.
No. 5634, homo-PET and highly shrinkable copolymer P
The expansion and contraction rate of the composite yarn in combination with ET is at most 2
%.

Further, the elastic modulus of elasticity needs to be 90% or more in order to maintain the form stability, and is more preferably 93% or more. The higher the elongation modulus is, the more excellent the strain recovery property is, and the more excellent the shape stability is. It should be noted that PE having an intrinsic viscosity difference as described in
The elastic modulus of the T-type composite yarn is about 83%.

PTT composite fibers satisfying both the above-mentioned characteristics of stretching and elongation of 120% or more and stretching and elasticity of 90% or more have characteristics that they are easily stretched, and that the strain corresponding to the stretch is easily restored to the original. An excellent stretch material can be obtained.

Further, when the composite interface between the two components of the highly crimpable polyester-based composite fiber of the present invention is linear in the fiber cross section, the ability to develop crimp becomes higher and the stretchability is improved. As an index indicating the linearity of the composite interface, FIG.
At the composite interface of the fiber cross section shown in FIG. 3, the radius of curvature R (μm) of a circle tangent to three points of points a and b having a depth of 2 μm from the fiber surface toward the center and the center c of the interface is determined.
d is preferably ^0.5 or more. Here, d indicates the fineness (decitex) of the single fiber. More preferably, the radius of curvature R is 15d ^0.5 or more. 2 (a) to 2 (g) each show a fiber cross section in which the radius of curvature R is 10d ^0.5 or more and which is preferably used in the present invention.

The cross-sectional shape of the highly crimpable polyester composite fiber of the present invention may be a round cross section, a triangular cross section, a multi-lobal cross section, a flat cross section, an X-shaped cross section, or any other known cross section. Although not limited, a semicircular side-by-side (a) having a round cross section as shown in FIG. A targeted triangular cross section side-by-side (g) or the like is preferably used.

As described above, according to the present invention, it is possible to obtain a stretch material with improved crimp expression ability under the constraint of a woven fabric. is important. When a polymer having a large difference in intrinsic viscosity is compounded side-by-side as in the present invention, the resulting yarn has good crimping properties, but the spun yarn is excessively bent toward the high-viscosity component side, thus deteriorating the spinnability. However, as a result, unevenness in the thickness of the fiber in the longitudinal direction is generated, and as a result, unevenness is generated when the fabric is used. Therefore, the fineness variation rate U% is 2 in order to satisfy stable yarn-making properties, stretchability and good quality.
% Or less.

The highly stretchable polyester composite fiber of the present invention needs to have a single fiber fineness of 1 dtex or more and 3 dtex or less in order to improve softness. When the single fiber fineness is larger than 3 dtex, the softness of the fabric is lacked, and when the single fiber fineness is less than 1 dtex, the yarn forming property is deteriorated.

The highly stretchable polyester-based composite fiber of the present invention can be used alone, but when used in combination with a low shrinkage yarn or a spontaneously elongated yarn, a stretchiness and a resilience are imparted to the stretch property. Can be preferred.

Applications utilizing the features of the present invention include fabrics, knits, non-woven fabrics, and cushion materials, which can be appropriately selected according to the purpose, and can be suitably used for shirts, blouses, pants, suits, blousons, and the like. .

Next, a preferred method for producing the high crimp polyester conjugate fiber of the present invention will be described.

In the highly stretchable polyester composite fiber of the present invention, two types of PTT having different intrinsic viscosities are respectively arranged and merged at the upper portion of the discharge hole to form a side-by-side composite flow. It is discharged from a discharge hole for obtaining. After the discharged yarn is cooled and solidified,
It may be manufactured by a two-step method of once winding and drawing, or may be manufactured by a direct spinning drawing method of drawing directly after spinning.

Further, in order to stably produce the highly stretchable polyester-based composite fiber of the present invention, the intrinsic viscosity of each component and the difference in intrinsic viscosity between the components are important. Even if it is a conjugate fiber, it is not practical if the viscosity of one side component is too low and there is no fiber forming ability, or if it is too high and a special spinning device is required. Further, the degree of bending (bending phenomenon) of the yarn immediately below the discharge hole is determined by the difference in viscosity between the components, and this greatly affects the yarn forming property. Therefore, the intrinsic viscosity (IV) of each component is preferably a combination satisfying the following formula.

When performing composite spinning, it is necessary that the intrinsic viscosity (IV) of the low-viscosity PTT is 0.6 or more. 0.
When the number is 6 or more, the fiber-forming property is improved, and the yarn-making property is improved. The low viscosity PTT has an intrinsic viscosity (IV) of 0.
If it is less than 6, the degree of polymerization is too low, resulting in poor fiber-forming ability, poor spinning properties, and low strength of the resulting yarn. When the difference ΔIV in intrinsic viscosity between the high-viscosity component and the low-viscosity component of PTT is larger than 0.6, a yarn having excellent crimping properties can be obtained. It is more preferable because it becomes an excellent raw yarn. On the other hand, when ΔIV is 1.20 or more, the obtained yarn has good crimp characteristics, but the spun yarn excessively bends toward the high-viscosity component side, and thus cannot be stably produced for a long time. Is not preferred. Therefore, in order to satisfy both stable spinning properties and stretch recoverability, ΔIV needs to be larger than 0.6 and smaller than 1.2.

Also, the spinning temperature is 250 to 250, because of PTT.
The temperature is preferably set to 270 ° C.

In order to make the U% of the composite fiber 2% or less, the spinning speed is set to 2000 m / min or less, more preferably 1500 m / min.
m / min or less. In particular, improving the measurement performance of the die, reducing the depth of the die surface, minimizing the space existing from the die surface to the chimney, cooling the discharged yarn uniformly, and further reducing the spinning tension during take-off Up is effective. In the stretching step, stretching is performed at a high magnification while sliding on the scraping body. In consideration of operability, it is preferable that the film is stretched so as to have a breaking elongation of preferably 40% or less, more preferably 35% or less. Since the stretching tension can be increased by the frictional resistance of the scraping body, U% is also improved by increasing the internal strain. Further, the heat setting temperature is preferably in the range of 110 to 170 ° C. from the viewpoint of stretchability and handleability in the higher order process. The stretching temperature is preferably set to 50 to 80 ° C.

[0033]

The present invention will be described below in detail with reference to examples. In addition, the measuring method in the Example used the following method.

A. Intrinsic viscosity orthochlorophenol (hereinafter abbreviated as OCP) 10
0.8 g of the sample polymer was dissolved in ml, and the relative viscosity ηr was determined at 25 ° C. using an Ostwald viscometer by the following equation to calculate IV.

Ηr = η / η₀= (T × d) / (t₀× d₀) IV = 0.0242ηr + 0.2634 where η: viscosity of polymer solution, η₀: Viscosity of OCP,
t: Fall time of solution (sec), d: Density of solution (g / cm)
^Three), T₀: Fall time (sec) of OCP, d ₀  : Density of OCP (g / cm^Three).

B. Stretching elongation and elasticity (according to JIS L1090 (stretchability) C method) Boiling water treatment is performed for 15 minutes while a processing load of 3.53 × 10 ^-3 cN / dtex is applied to a fiber cassette having an original length of 560 mm. After
Air dry and heat dry at 170 ° C for 5 minutes.
Next, after holding an initial load of 1.76 × 10 ⁻³ cN / dtex for 30 seconds, the cassette length L0 is measured. Further, immediately remove the load, hold a constant load of 0.09 cN / dtex for 30 seconds, measure the length L1, and immediately remove the load. After leaving for 2 minutes, a load of 1.76 × 10 ^-3 cN / dtex is suspended and 3
After holding for 0 seconds, measure the length L2. From the obtained lengths L0, L1 and L2, the stretch and stretch ratio and stretch elastic modulus are determined by the following formulas.

Stretching elongation (%) = [(L0−L1) / L0] × 100 Stretching elasticity (%) = [(L1−L2) / (L1−L0)] × 1
00 C.I. Fineness fluctuation rate (U%) A commercially available Uster Evenness T
Ester (manufactured by Keiki Kogyo Co., Ltd.) is used. Select the measurement slot to use depending on the total fineness of the yarn,
Approximately 1500 rpm with a twisting machine at a yarn speed of 200 m / min
Measurement is performed by a normal test while applying a rotation of m and twisting. The U% value is measured at any five points of the measurement sample, with three minutes of measurement being one measurement, and expressed as an average value.

D. Softness A fabric was made using the obtained yarn, and a three-stage sensory evaluation was performed. ○○ is excellent in softness, △ is PET / P
ET type bimetal yarn level, x, lacks softness.

Example 1 A homo-PTT having an intrinsic viscosity (IV) of 1.44 and a homo-PTT having an intrinsic viscosity (IV) of 0.72 were separately melted, and had a structure shown in FIG. 4 at a spinning temperature of 260 ° C. The mixture is discharged from a 12-hole composite spinneret at a composite ratio (weight%) of 50:50, and is taken up at a spinning speed of 1400 m / min. 165 dtex.
A 24-filament unstretched yarn of side-by-side composite structure (fiber cross section is FIG. 2a) was obtained. Hot roll
Using a hot plate stretching machine (yarn length: 20 cm, surface roughness: 3S), the film was stretched at a hot roll temperature of 70 ° C., a hot plate temperature of 145 ° C., and a stretching ratio of 3.0 times to obtain 55 dtex and 24 filaments (single filament). A drawn yarn having a fiber fineness d: 2.3 dtex was obtained. Both spinning and drawing exhibited good spinnability, and no yarn breakage occurred. The elastic elongation was 141.2%, and the elastic modulus was 94.9%, showing excellent elongation recovery. In addition,
The fineness variation rate (U%) was as good as 0.3%, and a high quality cloth could be obtained. In addition, the fabric obtained from the original yarn was very excellent in softness since the single yarn fineness was as small as 2.3 dtex.

Example 2 Evaluation was made in the same manner as in Example 1 except that a combination of a homo-PTT having an intrinsic viscosity (IV) of 1.27 and a homo-PTT having an intrinsic viscosity (IV) of 0.65 was used. As a result, the stretching elongation was 130%, the stretching elasticity was 92%, and the fineness variation (U%) was 0.4%. In Example 2, the bending immediately below the spinneret was small, and the spinning property was good. Further, although not superior to Example 1, it exhibited excellent elongation recovery properties and softness, and a high quality fabric was obtained.

Comparative Example 1 Evaluation was carried out in the same manner as in Example 1 except that a combination of homo-PTT having an intrinsic viscosity (IV) of 1.34 and homo-PBT having an intrinsic viscosity (IV) of 0.86 was used. The stretch rate is 2
9.6%, elastic modulus 92.0%, fineness variation (U
%) Was 0.2%, which was excellent in recoverability, softness, and quality as a fabric, but poor in elongation.

Comparative Example 2 A combination of homo-PBT having an intrinsic viscosity (IV) of 1.80 and homo-PTT having an intrinsic viscosity (IV) of 0.62 was spun at a spinning temperature of 270 ° C. and at a first hot roll temperature of 85 ° C. Evaluation was performed in the same manner as in Example 1 except that the film was stretched. As a result, the stretch ratio was 76.3%, and the stretch modulus was 94.7%.
%, And the fineness variation (U%) was 0.2%, and although the recoverability, softness, and quality of the fabric were excellent, the stretchability was poor.

Comparative Example 3 A combination of a homo PTT having an intrinsic viscosity (IV) of 1.18 and a homo PPT having an intrinsic viscosity (IV) of 0.65 was spun at a spinning temperature of 260 ° C. A drawn yarn was obtained. In this polymer combination, the viscosity difference ΔIV is as low as 0.53, so that the stretching and elongation is slightly lower at 110%, the stretching elasticity is 88%, and the fineness variation (U%) is 0.6.
%, Which was slightly inferior to Example 1.

Comparative Example 4 A method similar to that of Example 1 except that a combination of a homo PET having an intrinsic viscosity (IV) of 0.78 and a homo PET having an intrinsic viscosity (IV) of 0.51 was used and the spinning temperature was 290 ° C. Table 1 shows the results of the evaluation. Although the yarn-forming properties were relatively good, the stretching elongation was 1.8%, the stretching elasticity was 83.2%, and the fineness variation (U%) was 1.0%, which was poor in elongation recovery. Was.

Comparative Example 5 A drawn yarn was obtained in the same manner as in Example 1 using homo PTT having an intrinsic viscosity (IV) of 1.18 and homo PTT having an intrinsic viscosity (IV) of 0.58. In Comparative Example 5, the low viscosity component I
Since V was too low, the fiber-forming ability was poor, and the spinning property was poor. In addition, the properties of the obtained yarn also showed an expansion / contraction rate of 40%.
%, Stretch elasticity 89%, fineness variation (U%) 2.1
%, Poor elongation recovery and quality, and lacked the potential as a stretch material. Comparative Example 6 A combination of a homo-PTT having an intrinsic viscosity (IV) of 1.18 and a homo-PTT having an intrinsic viscosity (IV) of 0.88 was used, and a low-IV polymer was inserted from the side into a high-IV polymer immediately above a die discharge hole. As a result of evaluation in the same manner as in Example 1 except that the method was adopted, the stretching elongation was 2.0%, the stretching elasticity was 87%, the fineness variation (U%) was 0.8%, and the composite interface R was It was 20 μm. Comparative Example 6 had good yarn-making properties, but was inferior in crimp development ability and elongation recovery properties, and lacked the potential as a stretch material.

Comparative Example 7 The results evaluated in the same manner as in Example 1 except that a combination of a homo-PTT having an intrinsic viscosity (IV) of 1.61 and a homo-PTT having an intrinsic viscosity (IV) of 0.40 were used. It is shown in FIG. With the polymer combination of Comparative Example 7, the bending immediately below the die was severe and spinning could not be performed.

Comparative Example 8 When spinning was performed using the die having a large discharge hole diameter in Example 1, the back pressure of the die became 20 kg. as a result,
The fineness variation rate U% was 3.6%, and staining spots and grain spots occurred, resulting in poor quality.

Comparative Example 9 In Example 1, the puck was changed to 20
cm, the distance from the ejection surface to the chimney surface was increased, resulting in insufficient cooling. as a result,
U% was 2.8%, degrading the quality.

Comparative Example 10 A drawn yarn having 55 dtex and 12 filaments (single fiber fineness: 4.6 dtex) was obtained in the same manner as in Example 1 except that the number of filaments was changed to 12F. The obtained drawn yarn was excellent in stretchability, but lacked in softness when formed into a fabric, resulting in a rough texture.

Comparative Example 11 In Example 1, a drawn yarn having a side-by-side composite structure having a single fiber fineness of 0.9 dtex was obtained in the same manner as in Example 1 except that the number of filaments was changed to 60F. Since the single fiber fineness was too small, yarn breakage frequently occurred during spinning, and a yarn could not be obtained.

[0051]

[Table 1]

[0052]

[Table 2]

[0053]

As described above, by using the highly stretchable polyester-based composite fiber of the present invention, the stretch recovery property under the constraint of the woven fabric, which has been a problem in the past, is improved, and a high-quality fabric excellent in stretchability and softness can be obtained. Obtainable.

[Brief description of the drawings]

FIG. 1 is a model diagram for explaining a radius of curvature R of a composite interface in a fiber cross section of a fiber of the present invention.

FIG. 2 is a view showing a fiber cross-sectional shape of the fiber of the present invention.

FIG. 3 is a stress-elongation curve after boiling water treatment of the present invention and fibers other than the present invention.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4L041 BA02 BA05 BA10 BA32 BC17 BD13 CA08 DD01 DD04 4L045 AA05 BA03 BA21 BA36 BA50 BA57 BA60 CA25 DA42 DC02

Claims (2)

[Claims] 1. A composite fiber comprising two kinds of polyester polymers bonded in a side-by-side type, wherein each of the two kinds of polyester polymers is a polyester mainly composed of polytrimethylene terephthalate, and the intrinsic viscosity difference between the two components. Satisfies the following formula, and the fineness variation rate U% value of the multifilament yarn is 2% or less, the stretchable elongation is 120% or more, and the stretchable elastic modulus is 90% or more, wherein the single fiber fineness is 1 dtex or more and 3 dtex or less. Highly stretchable polyester composite fiber. IV of intrinsic viscosity of high viscosity polymer
(H) When the intrinsic viscosity of the polymer on the low viscosity side is IV (L) and the intrinsic viscosity difference between the two polymers is ΔIV, 1.20>ΔIV> 0.6 IV (L) ≧ 0.6 Elongation rate (%) = [(L1-L0) / L0] × 100 Stretch elastic modulus (%) = [(L1-L2) / (L1-L0)] ×
100 L0: 15 minutes of boiling water treatment and 17 of dry heat treatment with a processing load of 3.53 × 10 ⁻³ cN / dtex applied to a 560 mm long scab.
Perform 0 ° C x 5 minutes, then remove the processing load, and 1.76 x ^10-3 cN
Latch length when the initial load of / dtex is suspended for 30 seconds L1: Latch length when the initial load is removed and constant load of 0.09cN / dtex is suspended for 30 seconds L2: Initial load 1.76 again 2 minutes after the constant load is removed × 10 ^-3 cN /
Length of skewer when dtex is hung for 30 seconds 2. The highly stretchable polyester composite fiber according to claim 1, wherein the radius of curvature R of the composite interface between the two types of polyester polymers has the following relationship with the single fiber fineness. Curvature radius R (μm) ≧ 10d ^0.5 d: single fiber fineness (decitex)