JP2000160433A - Crimpable conjugate fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a crimpable conjugate fiber capable of being dyed with basic dyes, having a soft touch, having an excellent repulsive force, also when subjected to an alkali reduction treatment, and capable of giving a high grade fabric, by using a specific side-by-side conjugate fiber having prescribed physical properties. SOLUTION: This crimpable conjugate fiber comprises a side-by-side type conjugate fiber which comprises (A) a polyester copolymerized with 0.5-10 mol.% of a compound of the formula [R1-R10 are each H, an ester-forming functional group or an alkyl, provided that one or two of R1-R10 are the ester-forming functional groups; (x) is 0 or 1; (y) is an integer satisfying the inequality: and 1<=(x)+(y)<=3], such as norbornene-2,3-dimethanol, and 0.5-5 mol.% of structural units each having a metal sulfonate group, such as 5-sodium sulfoisophthalic acid, and (B) a fiber-forming polymer, such as a polyester or a polyamide, having a melting point of >=150 deg.C, and satisfies inequalities II to IV. After subjected to an alkali reduction treatment, the crimpable conjugate fiber has a crimp extension (K1) of >=3% and a crimp extension retention of 60%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a side-by-side conjugate fiber having a soft feel and excellent crimp elongation. More specifically, the present invention relates to a conjugate fiber which can be dyed with a basic dye, and which can be made into a high-quality cloth which is bulky, swelling, tight, elastic and elastic when formed into a woven or knitted fabric.

[0002]

2. Description of the Related Art Conventionally, polyurethane elastic fiber yarns having excellent elasticity have been used to impart excellent elasticity to woven fabrics. However, this polyurethane elastic fiber yarn is unique to polyurethane. However, there is a drawback that the texture is hard and therefore the texture of the fabric is reduced, or the drape property of the fabric is reduced. To avoid this drawback, weaving a woven fabric using a combination of polyurethane elastic fiber yarn and polyester yarn has also been performed, but both yarns have a difference in dyeability, and dye the woven fabric. In this case, there is a disadvantage that the dyeing process becomes complicated or it becomes difficult to dye a desired color (in many cases, a dark color). In addition, a false twisted yarn is used as a yarn constituting a woven fabric to impart elasticity to the woven fabric. The false twisting yarn has inherent torque due to twisting and untwisting, and the torque imparts elasticity to the yarn. However, this torque not only contributes to the elasticity of the woven fabric, but also tends to transfer to the grain on the woven fabric surface. Therefore, the woven fabric composed of the false twisted yarn has good stretchability, but is liable to be textured on the surface. In order to prevent texture from appearing on the woven fabric, heat treatment is applied to the woven fabric to reduce the torque of the false twisted yarn. However, there is a drawback that is reduced.
The elongation recovery was also insufficient.

On the other hand, not two kinds of polymers having different shrinkage characteristics or two kinds of polymers having a difference in intrinsic viscosity, that is, two kinds of polymers having a difference in degree of polymerization, as one component, are not polyurethane elastic fiber yarns or false twisted yarns. Crimped conjugate fibers joined in a side-by-side type are widely known. For example, WO95 / 04846 proposes a side-by-side conjugate fiber having a high crimping property capable of repelling a binding force of a woven fabric structure. However, even a conjugate fiber having a sufficient crimping performance has a problem that the texture of the woven or knitted material becomes hard if the conjugate fiber has a large thermal deformation, that is, a large boiling water shrinkage. Also, for the purpose of a basic dye-dyable type conjugate fiber, a crimpable conjugate fiber joined in a side-by-side type using a polyester containing a metal sulfonate group as one component is known (see, for example, Japanese Patent Application Laid-Open No. Sho 64). However, the side-by-side conjugate fiber containing a polyester copolymerized with a metal sulfonate group as one component has a problem that the crimping performance is reduced after the alkali weight reduction treatment, so that a good texture of the woven or knitted fabric cannot be obtained. Had.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned drawbacks of the conventional crimpable conjugate fiber, to be dyeable with a basic dye, and to have a soft texture. An object of the present invention is to provide a crimpable conjugate fiber having excellent rebound and excellent crimping properties even after alkali reduction treatment.

[0005]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, used a specific copolymerized polyester as a polymer having a high shrinkage stress, and further devised a production method. Thus, the present inventors have found that the above object is achieved, and have reached the present invention.

That is, the present invention provides a compound represented by the following structural formula (I) in an amount of 0.5 mol% to 10 mol% and a structural unit having a metal salt sulfonate group of 0.5 mol%.
A side-by-side type composite fiber comprising a polyester (A) copolymerized in an amount of at least 5 mol% and a fiber-forming polymer (B) having a melting point of 150 ° C. or more, and the following (1) to
A crimpable conjugate fiber characterized by satisfying the formula (3).

Embedded image In the formula, R _{1 to} R ₁₀ are an ester-forming functional group, a hydrogen atom,
A group selected from an alkyl group and R _{1 to} R ₁₀
One or two of them are ester-forming functional groups.
X is 0 or 1, and y is an integer satisfying 1 ≦ x + y ≦ 3. Boiling water shrinkage (Wsr) ≦ 15% (1) Crimp elongation (K1) ≧ 5% (2) Thermal peak stress ≧ 0.15 g / d (3)

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In order to obtain a woven or knitted fabric having the desired crimping properties, dyeing a basic dye and having a soft texture in the present invention, a compound represented by the above structural formula (I) Further, it is necessary that a specific amount of a structural unit having a metal salt sulfonate group is copolymerized with the polyester (A). In the compound represented by the structural formula (I), examples of the ester-forming functional group include a hydroxy group, a hydroxyalkyl group, a carboxyl group, and an ester-forming derivative thereof. The alkyl constituting the hydroxyalkyl group is not limited, but is preferably an alkyl having 1 to 4 carbon atoms, such as a hydroxymethyl group, a hydroxyethyl group, a hydroxypropyl group, or a hydroxybutyl group, and may be a branched alkyl.

The ester-forming derivative of a carboxyl group includes a carboxylic acid having 1 to 1 carbon atoms such as methyl ester, ethyl ester, propyl ester and butyl ester.
Alkyl esters of 4 are preferred.

The compound represented by the structural formula (I) needs to have one or two ester-forming functional groups, and is highly copolymerized in the polyester molecular chain as a polyester fiber. It is preferable in terms of expression of shrinkage characteristics, polymerizability, and the like, and from this point, it is preferable that the number of ester-forming functional groups is two. In that case, the ester-forming functional groups may be of the same type or of different types.

Further, in the compound, a carbon atom to which the ester-forming functional group is not bonded has a hydrogen atom or an alkyl group bonded thereto, but the ester-forming functional group is not bonded in that the polymerizable property is not inhibited. It is preferable that a hydrogen atom is bonded to carbon. In addition, as an alkyl group, a C1-C5 alkyl group, such as a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group, is mentioned, and the said group may be branched.

Examples of such compounds include norbornane 2,3-dimethanol, norbornane 2,3-diethanol, norbornane 2,3-dicarboxylic acid, norbornane 2,3-dicarboxylic acid dimethyl ester, norbornane 2,3-dicarboxylic acid Acid diethyl ester, perhydrodimethanonaphthalenediethanol, perhydrodimethanonaphthalenediethanol, perhydrodimethanonaphthalenedicarboxylic acid, dimethyl perhydrodimethananaphthalenedicarboxylate, tricyclodecanedimethanol, tricyclodecanediethanol, tricyclo Decanedicarboxylic acid, tricyclodecanedicarboxylic acid dimethyl ester, tricyclodecanedicarboxylic acid diethyl ester, and the like.In these compounds, an ester-forming functional group is bonded. Compounds have not alkyl carbon is bonded to also be mentioned. Further, the present invention includes a compound to which other substituents other than the alkyl group are bonded.

Among the above compounds, from the viewpoints of polymerizability, spinnability, fiber strength and shrinkage performance, norbornane 2,3-dimethanol, norbornane 2,3-dicarboxylic acid, norbornane 2,3-dicarboxylic acid dimethyl ester, Hydrodimethanonaphthalenediethanol, perhydrodimethanonaphthalenedicarboxylic acid, perhydrodimethanonaphthalenedicarboxylic acid dimethyl ester, tricyclodecane dimethanol, tricyclodecane diethanol, tricyclodecane dicarboxylic acid, tricyclodecane dicarboxylic acid dimethyl ester, etc. Is preferred.

[0013] Further, from the viewpoint of polymerizability, norbornane 2,3-dimethanol, norbornane 2,3-dicarboxylic acid, norbornane 2,3-dicarboxylic acid dimethyl ester, perhydrodimethanonaphthalenedimethanol, perhydrodimethanol In naphthalenedicarboxylic acid and perhydrodimethanonaphthalenedicarboxylic acid dimethyl ester, two ester-forming functional groups are preferably located at the trans position.

Further, in the present invention, it is necessary that a component containing a metal salt sulfonate group is copolymerized.
The compounds generally represented by the following formula (II) are used, but are preferred. Examples include 5-sodium sulfoisophthalic acid, dimethyl 5-sodium sulfoisophthalate,
-Tetrabutylphosphonium sulfoisophthalic acid.

Embedded image Here, M represents an alkali metal such as Na, Li, and K,
R, R 'is an alkyl group or, - (CH ₂₎ n indicates nOH represents an integer of 2 or more.

The polyester in the present invention is a polyester mainly containing terephthalic acid as a main dicarboxylic acid component and at least one alkylene glycol selected from ethylene glycol, trimethylene glycol and tetramethylene glycol as a main glycol component. . The fourth component may be copolymerized in addition to the compound represented by the structural formula (I) and the compound containing a metal sulfonate group within a range not to impair the object of the present invention.

As the fourth component, isophthalic acid,
Phthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid,
4,4'-diphenylmethanedicarboxylic acid, 4,4'-
Diphenylsulfone dicarboxylic acid, 4,4'-diphenylisopropylidene dicarboxylic acid, 1,2-diphenoxyethane-4 ', 4 "dicarboxylic acid, anthracene dicarboxylic acid, 2,5-pyridine dicarboxylic acid, diphenoxy ketone dicarboxylic acid, etc. Aromatic dicarboxylic acids; aliphatic dicarboxylic acids such as malonic acid, succinic acid, adipic acid, azelaic acid, sebacic acid; alicyclic dicarboxylic acids such as decalin dicarboxylic acid and cyclohexanedicarboxylic acid; β-
Hydroxycarboxylic acids such as hydroxyethoxybenzoic acid, p-oxybenzoic acid, hydroxypropionic acid and hydroxyacrylic acid; carboxylic acids derived from these ester-forming derivatives; aliphatic lactones such as ε-caprolactone; hexamethylene glycol; Aliphatic diols such as neopentyl glycol, diethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol; hydroquinone, catechol, naphthalene diol, resorcinol, bisphenol A, ethylene oxide adduct of bisphenol A,
Examples thereof include aromatic diols such as bisphenol S and ethylene oxide adduct of bisphenol S; and alicyclic diols such as cyclohexane dimethanol.
Only one or more of these fourth components may be copolymerized.

Further, the polyester (A) of the present invention includes:
Polyhydric carboxylic acids such as trimellitic acid, trimesic acid, pyromellitic acid, and tricarballylic acid within a range where the polyester is substantially linear; polyhydric alcohols such as glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol May be copolymerized.

The content of the compound represented by the structural formula (I) in the polyester (A) is from 0.5 mol% to 10 mol%, preferably from 3 mol% to 10 mol%, based on the dicarboxylic acid component constituting the polyester. The range is 8 mol% or less. When the content of the compound is less than 0.5 mol%,
In addition to not being able to obtain sufficient crimping performance and good texture, there is no effect of improving low resistance to alkali caused by copolymerization of a compound containing a metal salt sulfonate group. Compression performance is lost. On the other hand, if the content of the compound exceeds 10 mol%, it is not preferable because a crystalline polyester is hardly obtained and the thermal deformation, that is, the shrinkage ratio of boiling water increases, and the texture of the woven or knitted fabric becomes hard. The content of the compound containing a metal salt sulfonate group in the polyester (A) is from 0.5 mol% to 5 mol%, more preferably from 1 mol% to 3 mol%, based on the dicarboxylic acid component constituting the polyester.
Mol% or less. When the content of the compound is less than 0.5 mol%, the dyeing properties of the basic dye are insufficient and a deep color cannot be expressed. On the other hand, if the content of the compound is more than 5 mol%, good crimping performance cannot be obtained even if the composition of the polymer (B) is controlled owing to the thickening effect, and furthermore, the alkali resistance is low and the alkali weight is reduced. Crimp performance is lost.

The polyester (A) of the present invention can be polymerized by a usual method. For example, by directly esterifying terephthalic acid and alkylene glycol, transesterifying a lower alkyl ester of terephthalic acid such as dimethyl terephthalate with alkylene glycol, or reacting terephthalic acid with alkylene oxide A first-stage reaction for producing an alkylene glycol ester of terephthalic acid and / or a low polymer thereof, and a polycondensation reaction by heating the reaction product obtained in the first stage under reduced pressure to a desired degree of polymerization Produced by a second stage reaction. At that time, the compound of the structural formula (I) can be added at any stage until the polycondensation reaction is completed, for example, to the starting material of the polyester, or after the transesterification reaction and before the polycondensation reaction. Further, the metal salt sulfonate-containing compound can be added after the transesterification reaction and before the polycondensation reaction. Further, in order to increase the degree of polymerization, solid phase polymerization may be performed after polymerization in a liquid phase.

The polyester (A) desirably has an intrinsic viscosity (measured at 30 ° C. using a mixed solvent of phenol / tetrachloroethane (weight ratio: 50/50)) of 0.5 to 1.5.

The fiber-forming polymer (B) used in the present invention is not particularly limited as long as it has a melting point of 150 ° C. or higher. Examples thereof include polyester or polyamide such as nylon 6, nylon 12, and nylon 66. It may contain a copolymer component. Melting point 15
If the temperature is lower than 0 ° C., heat setting for imparting a texture to the composite yarn, high-temperature dyeing, and the like are difficult to be performed, which is not practical. Further, if the melting point is too high, the spinnability and the like may be reduced. Therefore, a polymer having a melting point of 270 ° C. or less is preferable.

The conjugate fiber of the present invention has a form in which the polyester (A) and the fiber-forming polymer (B) are joined in a side-by-side type in the fiber cross section. Means that the composite ratio of the polyester (A) and the polymer (B) is (A) :( B) = 30: 70
７０70: 30, particularly preferably 40:60 to 60:40. Most preferably, both components are between 45:55 and
This is a case where the composite spinning is performed at a composite ratio of 55:45.
Whichever the ratio is, the spinnability tends to be poor.

The cross-sectional shape of the conjugate fiber of the present invention is not particularly limited, and may be a polygonal cross-section such as a round cross-section, an elliptical cross-section, a flat cross-section, a triangle, a square, a pentagon, a hexagon, a T-shaped cross-section, a U-shaped cross-section, and a W-shaped cross-section. Examples include a letter-shaped cross section, a multi-branched cross section, a multi-leaf cross section, and a hollow cross section.

In the present invention, it is important that the crimp elongation rate and boiling water shrinkage rate of the conjugate fiber satisfy the following formulas (1) to (3). X is 0 or 1, and y is 1
It is an integer satisfying ≦ x + y ≦ 3. Boiling water shrinkage (Wsr) ≦ 15% (1) Crimp elongation (K1) ≧ 5% (2) Thermal peak stress ≧ 0.15 g / d (3) More preferably, crimp elongation retention after alkali weight loss Is 60% or more.

If the crimp elongation is less than 5%, a sufficient texture cannot be obtained in a woven or knitted fabric. On the other hand, when the crimp elongation ratio is larger than 40%, the texture may be increased. More preferably, it is 8% or more and 30% or less.

If the boiling water shrinkage is more than 15%, the texture of the woven or knitted fabric becomes hard, which is not appropriate. Preferably, the boiling water shrinkage is 3% or more and 12% or less.

The conjugate fiber of the present invention has a high stress at the time of heat shrinkage, and is 0.15 g / dr or more. If it is less than 0.15 g / dr, it is restricted by the structure of the woven fabric and exhibits sufficient bulkiness. I can't have good swelling and tightness. More preferably, 0.18 g / dr
That is all. The conjugate fiber of the present invention has a crimp fastness of 1
0% or less, which is superior to the conventional one. In long-term use, sag is small and texture and characteristics can be maintained.

The conjugate fiber of the present invention may contain an antioxidant, an ultraviolet absorber, a fluorescent whitening agent, a matting agent, an antistatic agent, a flame retardant, and a flame retardant as long as it does not impair the present invention. ,
It may contain additives such as a lubricant, a colorant, a plasticizer, and an inorganic filler.

The conjugate fiber of the present invention can be formed into a fiber using a known melt conjugate spinning apparatus, and the above-mentioned crimp elongation, boiling water shrinkage, and thermal peak stress satisfy specific ranges. In order to obtain a conjugate fiber, it is important to employ the following spinning and drawing conditions in the fiberizing step. 1500 m / min ≦ Spinning take-up speed ≦ 3500 m / min Breaking draw ratio of spun yarn × 0.68 ≦ Drawing ratio ≦ Breaking ratio of spun yarn × 0.80 150 ° C. ≦ Drawing hot plate temperature

The viscosity of the polyester (A) and the fiber-forming polymer (B) is preferably set to satisfy the following formula from the viewpoint of crimp elongation performance and the ability to pass through the spinning / drawing process. 1000 <η ₀ (A) −η ₀ (B) <8800 η ₀ : 290 ° C. Melt viscosity when Shear rate is 0

[0031]

EXAMPLES The present invention will be described in detail with reference to the following examples, but the present invention is not limited to these examples. The method for measuring the characteristic values and the like in the examples is as follows.

Intrinsic viscosity: Measured at 30 ° C. using a mixed solvent of phenol / tetrachloroethane (weight ratio 50/50).

Melt viscosity: Capillograph (manufactured by Toyo Seiki)
Was used to measure the solvent viscosity η ₀ at a shear rate of 0 at 290 ° C.

Boiling water shrinkage: A sample is marked at intervals of 50 cm under an initial load of 1 mg / denier, then the sample is left in hot water of 98 ° C. under a load of 5 mg / denier for 30 minutes, and then taken out to remove 1 mg / denier load. Bottom mark interval L'c
m was measured and calculated by the following equation. Boiling water shrinkage (%) = [(50−L ′) / 50] × 100

Crimp elongation: The sample is treated with boiling water at 90 ° C. for 30 minutes while applying a load of 1 mg / d, then the load is removed and the sample is dried. Thereafter, a load of 1 mg / d is applied and the length l ₁ after 5 minutes.
Then, a load of 0.1 g / d was applied, and the length l ₂ after 30 seconds was measured. Crimp elongation rate = [(l ₂ −l ₁ ) / l ₂ ] × 100

Crimp elongation retention after alkali weight loss: Crimp elongation retention% = [(crimp elongation rate after 5% alkali weight loss) / (crimp elongation rate before alkali weight loss) × 100]

Crimp fastness: 1 mg at the time of measurement of crimp elongation and ₂ g of load 0.7 g / d were further removed for 30 seconds, and 1 mg was removed.
The length l ₃ after standing for 5 minutes under / d was measured and calculated by the following equation. Crimp fastness = [(l ₂ −l ₃ ) / l ₂ ] × 100

Dyeing property: The dyeing performance of the basic dye was evaluated as good or bad by sensory evaluation.

Texture: Initial texture Elongation, swelling, softness, tension, and stiffness were evaluated by a sensory evaluation as follows: 優 れ: very good ：: excellent △: slightly poor ×: poor In addition, regarding the sample for which the initial feeling was evaluated, 100 g of the sample was placed in an electric washing machine containing 40 g of a neutral detergent and 20 l of water, and a washing time of 6 minutes and a dehydration time of 1 hour.
After washing the whole sample under the conditions of 8 minutes, a rinsing time of 8 minutes and a dehydration time of 2 minutes, washing is performed by a natural drying method, and then a load of 50 g is applied to the sample for 1 minute. Wash and load 3
After repeating 0 times, the texture was evaluated in the same manner as the initial texture.

Production Example 1 of Polyester (A) Tricyclodecane-2,2-dimethanol (TC2-2)
DM) (abbreviated as DM) 4.2 mol%, ethylene glycol 95.
Diol component consisting of 8 mol%, and terephthalic acid 9
8.5 mol% and 1.5 mol% of dimethyl (5-sodium sulfo) isophthalate are used as dicarboxylic acid components, and the molar ratio of the diol component to the dicarboxylic acid component is adjusted to 1.2: 1. The slurry was subjected to an esterification reaction under pressure (at an absolute pressure of 2.5 kg / cm ² ) at a temperature of 250 ° C. until the esterification ratio became 95% to produce a low polymer. Next, 3
Add 50ppm antimony trioxide, absolute pressure 1to
The low polymer was polycondensed at 280 ° C. for 1.5 hours under a reduced pressure of rr to produce a polyester having an intrinsic viscosity [η] of 0.72 dl / g. This polyester is extruded from a nozzle into a strand and cut, and has a diameter of 2.8 mm and a length of 3.2 mm.
Was manufactured.

Example 1 Using the chip obtained in Production Example 1 and polyethylene terephthalate having η = 0.59 (melting point: 265 ° C.), using a usual melt spinning apparatus, a spinning temperature of 290 ° C. and a spinning speed Was spun at 3000 m / min to obtain a side-by-side composite undrawn yarn having a composite weight ratio of 50:50. This undrawn yarn is preheated at 85 ° C and 1.7 times (rupture draw ratio of the original spun yarn ×
0.7) and heat-treated at 170 ° C using a hot plate after stretching.
A drawn yarn of 0d / 24f was obtained. The obtained drawn yarn was made into a tubular knitted fabric and heat-treated at 160 ° C. for 10 minutes. The obtained tubular knitted fabric had very good initial texture and texture after washing and load application. Tables 1 and 2 show the details of the polyester (A) and the polymer (B), the physical properties of the fibers, and the results of the hand evaluation.

[0042]

[Table 1]

[0043]

[Table 2]

Examples 2-3 Copolymerized polyesters were evaluated in the same manner as in Example 1 except that the molar amounts of the copolymerized components of the copolyesters were changed as shown in Table 1. went. As a result, both the initial texture and the texture after washing load were excellent.

Example 4 Polyester polymerization and polymerization were carried out in the same manner as in Example 1 except that the drawing conditions were changed to a draw ratio of 1.75 times (rupture draw ratio of the original spun yarn × 0.72) and a hot drawing plate of 160 ° C. Evaluation of fiberization and tubular knitted fabric was performed.

Examples 5 to 6 Polyester polymerization, fiberization, and evaluation of knitted fabric were carried out in the same manner as in Example 1 except that the melt viscosity of the copolymerized polyester was changed according to Table 1.

Example 7 Except that the polymer (B) was changed to nylon 6, polymerization of polyester, fiberization, and evaluation of the knitted fabric were carried out in the same manner as in Example 1.

Examples 8 to 9 Polymerization of polyester, fiberization, and evaluation of tubular knitted fabric were performed in the same manner as in Example 1 except that the copolymerization components of the copolymerized polyester were changed according to Table 1.

Comparative Examples 1-4 Polymerization of polyester, fiberization, and evaluation of tubular knitted fabric were performed in the same manner as in Example 1 except that the molar amount of the copolymer component of the polyester (A) was changed according to Table 1.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4L031 AA18 AB01 AB09 AB26 CA01 CA07 CA08 4L035 BB33 BB56 BB91 CC03 DD02 DD20 EE01 FF10 HH10 4L041 AA08 AA20 AA25 BA02 BA05 BA09 BA60 BC04 BC05 BC20 BD14 CA06 CA12 DD01 DD05

Claims (4)

[Claims] 1. A compound represented by the following structural formula (I) is copolymerized by 0.5 to 10 mol% and a structural unit having a metal salt sulfonate group to 0.5 to 5 mol%. A side-by-side composite fiber comprising a polyester (A) and a fiber-forming polymer (B) having a melting point of 150 ° C. or more, and satisfying the following formulas (1) to (3): Composite fiber. Embedded image In the formula, R _{1 to} R ₁₀ are an ester-forming functional group, a hydrogen atom,
A group selected from an alkyl group and R _{1 to} R ₁₀
One or two of them are ester-forming functional groups.
X is 0 or 1, and y is an integer satisfying 1 ≦ x + y ≦ 3. Boiling water shrinkage (Wsr) ≦ 15% (1) Crimp elongation (K1) ≧ 5% (2) Thermal peak stress ≧ 0.15 g / d (3) 2. The crimp elongation rate (K1) after alkali reduction is 3% or more, and the crimp elongation retention rate is 60% or more.
The crimped conjugate fiber according to the above. 3. The crimpable conjugate fiber according to claim 1, wherein the fiber-forming polymer (B) having a melting point of 150 ° C. or higher is a polyester. 4. The crimpable conjugate fiber according to claim 1, wherein the fiber-forming polymer (B) having a melting point of 150 ° C. or higher is a polyamide.