JP2000054228A - Polyamide-based conjugate fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyamide-based conjugate fiber having tenseness, firm texture and dry feeling, excellent in bulkiness and drape and useful for woven/ knit fabrics by setting the conjugate ratio within a given range and arranging an aliphatic polyester to partially expose on a part of the fiber surface. SOLUTION: This fiber is a conjugate fiber consisting of (A) a polyamide- based polymer such as Nylon-6 and (B) a polylactic acid-based polymer or a blend of a polymer selected from a group comprising poly(D-lactic acid), poly(L-lactic acid), polymers of D-lactic acid, L-lactic acid and/or optical isomers of their blend, a copolymer of D-lactic acid with a hydroxycarboxylic acid and a copolymer of L-lactic acid with a hydroxycarboxylic acid wherein the conjugate ratio A/B is (5:95) to (95:5) and the component B is disposed to partially expose on a part of the fiber surface. The component B is preferably reduced in its weight within a range 10-100 wt.% from the polyamide-based conjugate fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a polyamide having the fiber properties and characteristics inherent to polyamide and having excellent alkali weight loss properties.
The present invention relates to a polyamide-based composite fiber having novel functionality.

[0002]

2. Description of the Related Art Polyamide fibers are widely used as general-purpose materials in industrial materials, clothing, general household materials, civil engineering, agricultural materials, sanitary materials, and the like. This is because the fiber strength is high and the Young's modulus is lower than that of the polyester fiber, so that the drape property is excellent and the dyeing property is excellent. However, there is a problem that it is difficult to impart functionality because it cannot be reduced in weight by alkali treatment, and it is difficult to develop it as another functional material.

On the other hand, in recent years, with regard to clothing materials mainly made of polyester, in order to pursue more functionality and impart drapability, irregularly shaped or shrinkable fibers have been used,
Materials and products have been pursued by applying alkali weight reduction processing using composite fibers using components having different alkali dissolution rates and making the most of aesthetics in a direction that matches humans. For this reason, alkali weight reduction treatment is currently an indispensable step for imparting bulkiness and drapability of the fabric, but the amount of low molecular polyester discharged from the alkali weight reduction waste liquid is now enormous. I have.

Further, conventional polyamide-based or polyester-based fibers and resins have a very low decomposition rate in a natural environment and generate a large amount of heat upon incineration, and therefore, a review from the viewpoint of protection of the natural environment is required. I have.

[0005] Therefore, in recent years, biodegradable fibers made of aliphatic polyesters have been developed and are expected to contribute to the protection of the natural environment. Aliphatic polyesters have excellent fiber performance and are expected as a fiber material with new features, but generally lack practicality due to their low melting point and vulnerability to alkali weight loss treatment. And the use is limited.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, and has a multifunctionality capable of imparting bulkiness, firmness, waist and dry feeling, and sometimes imparting bulkiness.
An object of the present invention is to provide an eco-friendly polyamide-based composite fiber including waste liquid treatment by reducing the amount of a biodegradable polymer component by alkali.

[0007]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have reached the present invention. That is, the present invention relates to a composite fiber comprising a polyamide polymer (A) and an aliphatic polyester (B), wherein the composite ratio (A / B) is 5/95 to 95/5, and The present invention provides a polyamide-based composite fiber, wherein the polyester (B) is arranged so as to be exposed at least on a part of the fiber surface.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

In the present invention, examples of the polyamide polymer (A) include nylon 6, nylon 66, nylon 46 and nylon 12. Further, two or more of these polymers may be used in combination.

The aliphatic polyester (B) constituting the polyamide conjugate fiber together with the polyamide polymer (A) includes (1) hydroxyalkyl carboxylic acids such as glycolic acid, lactic acid, hydroxybutyl carboxylic acid, etc.
(2) aliphatic lactones such as glycolide, lactide and butyrolactone; (3) aliphatic diols such as ethylene glycol, propylene glycol, butanediol, hexanediol and the like; (4) diethylene glycol;
Oligomers such as polyalkylene ethers such as dihydroxyethylbutane, polyethylene glycol,
Components derived from aliphatic polyester polymerization raw materials, such as polyalkylene glycols such as polypropylene glycol and polybutylene ether; and (5) aliphatic carboxylic acids such as succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid and decanedicarboxylic acid. Is the main component, that is, 6
0% by weight or more, a homopolymer of an aliphatic polyester, a block or random copolymer of an aliphatic polyester, and other components of the aliphatic polyester, such as aromatic polyester, polyether, polycarbonate, polyamide, It includes all copolymers and / or blends of 40% by weight or less of polyurea, polyurethane and the like.

Among these aliphatic polyester-based polymers, polylactic acid-based polymers, such as poly (D-lactic acid)
, Poly (L-lactic acid), a polymer of an optical isomer by D-lactic acid and L-lactic acid or a blend thereof, a copolymer of D-lactic acid and hydroxycarboxylic acid, L-lactic acid and hydroxycarboxylic acid Particularly preferred is a polymer selected from the group of a copolymer with an acid or a blend thereof.

The reason is that the polylactic acid-based polymer is
The softening point exceeds 100 ° C and the melting point is 120 ° C
Can be exceeded and the melting point is 120 ° C.
The fiber made of a polylactic acid-based polymer that exceeds 100% can be prevented from having a different texture, melting, deteriorating, or developing stain spots even when dyed at a normal dyeing temperature of 100 ° C. or more. That's why.

[0013] These aliphatic polyester-based polymers are easily reduced in weight by a heated alkaline solution, and the fibers of this single polymer have low strength and are not practical. In addition, to be a copolymer,
The higher the blend ratio with the optical isomer, the easier the weight loss with respect to the alkaline solution. In the case of a polylactic acid-based polymer, the blend ratio of the D-form to the L-form is a factor affecting heat resistance and biodegradability, and the purity of the L-form is reduced by the D-form, and the crystallinity is reduced. , Melting point drop is increased. In general, copolymerization can improve flexibility and elastic recovery, increase heat shrinkage, control decomposability and glass transition temperature, and improve adhesion with other components.

The polyamide-based conjugate fiber of the present invention needs to be arranged so that the aliphatic polyester (B) subjected to alkali weight reduction is exposed at least on a part of the fiber surface. The reason for this is to easily reduce the amount of alkali during the alkali treatment. By taking such a composite form and performing alkali weight reduction, it becomes easy to make fibers into irregular cross-sections, ultrafine, hollow, etc., and by reducing the alkali after fabric formation to reduce the bulk density of the fabric,
Functionality such as plump texture, firmness, waist, and improved water absorption can be imparted.

The composite cross-sectional shape in which the aliphatic polyester is arranged so as to be exposed at least on a part of the fiber surface is, for example, a round cross-section, an irregular cross-section, a hollow cross-section or a core as shown in FIGS. 1 (a) to 1 (k). Sheath type, eccentric core sheath type, parallel type, multi-core type,
The same or different combinations of various division type composite cross sections such as a radiation division type and a point target point symmetric division type are possible.

The conjugate ratio (weight ratio of polyamide polymer (A) / aliphatic polyester (B)) in the conjugate fiber of the present invention must be 5/95 to 95/5.
Outside of this range, the yarn production stability is degraded, the composite cross section is distorted, and / or the structure of the spinneret becomes complicated, so that the cost is undesirably increased. On the other hand, when the proportion of the aliphatic polyester (B) is large, the weight of the fiber itself after the alkali treatment becomes large, and it is not preferable because the weight cannot be controlled and the strength decreases. Therefore, the more preferable range of the composite ratio is 30/70 to 90/10, and the most preferable range of the composite ratio is 50/50 to 85/15.

The aliphatic polyester (B) in the conjugate fiber of the present invention is preferably made into a fabric, and
Preferably, the weight is reduced by 0%. When the weight loss rate of the aliphatic polyester (B) is less than 10%, the alkali weight loss effect as a composite yarn is small, and no functionality is exhibited. In addition, it does not exceed 100%, and in this case, an ultrafine fiber material made of only polyamide or a functional fiber material having a super deformability is obtained.

In the present invention, if necessary, a heat stabilizer, a crystal nucleating agent, a matting agent, a pigment, a light-proofing agent, a weathering agent, and the like may be added to the polyamide-based polymer (A) and the aliphatic polyester (B). Various additives such as antioxidants, antibacterial agents, fragrances, plasticizers, dyes, surfactants, surface modifiers, various inorganic and organic electrolytes, fine powders, flame retardants, etc. are added as long as the effects of the present invention are not impaired. can do.

The single fiber fineness of the polyamide composite fiber of the present invention is preferably selected from 0.5 to 100 denier. If the density is less than 0.5 denier, problems such as control of the solidification point when forming the fiber, improvement of the accuracy of the die hole, reduction in productivity due to reduction of the discharge amount, and easy occurrence of thread breakage occur. Not preferred. On the other hand, if it exceeds 100 denier, spinning and drawing are difficult in the step of producing ordinary long fibers, and special production equipment is required separately, which is undesirably high.

[0020] The strength of the conjugate fiber of the present invention is preferably as high as the practical range is widened, but it is particularly preferably at least 1.0 g / d. Problems may arise. The elongation of the fiber is not particularly limited, but is 10 to 80%.
Is preferred. If the elongation is less than 10%, problems may occur such as yarn breakage or poor drawability. On the other hand, if the elongation exceeds 80%, the dimensional stability after forming the fabric may be undesirably reduced.

The conjugate fiber of the present invention can be used alone or in combination with other fibers to produce knits, woven fabrics, various composite materials and other structures. When mixed with other fibers, synthetic fibers made of a fiber-forming polymer such as polyester fiber, nylon fiber, acrylic fiber, vinylon fiber, polypropylene fiber, polyethylene fiber, etc .; regenerated fibers such as rayon; Synthetic fibers, natural fibers such as wool, silk, cotton, hemp, and the like are employed, and spinning with synthetic fibers is also possible.

Next, an example of a method for producing the polyamide-based composite fiber of the present invention will be described, but the present invention is not limited to this method. In order to produce the polyamide-based composite fiber of the present invention, a spinning method and a drawing method using a known melt composite spinning device can be basically used.

First, a polyamide-based polymer (A) and an aliphatic polyester (B) are selected from the above-mentioned polymers, these polymers are individually melt-weighed, and the aliphatic polyester (B) is applied to the fiber surface. The fiber is spun from a composite spinneret device to be arranged, cooled, then oiled, and wound up.

Next, the wound yarn is hot-drawn or
Alternatively, the target conjugate fiber can be obtained by successively hot drawing without winding. The yarn wound at a high speed does not necessarily need to be thermally drawn. What is hot stretching?
This refers to drawing an undrawn fiber at a temperature equal to or higher than the glass transition temperature and equal to or lower than the softening temperature.

The above melt spinning has a winding speed of 100
Low speed spinning up to 2000 m / min, winding speed 2000-5
High-speed spinning at 2,000 m / min and ultra-high-speed spinning at a take-up speed of 5,000 m / min or more are possible, and a so-called spin draw method in which spinning and drawing are continuously performed is also preferably applicable.

The fiber form of the composite fiber of the present invention can be applied not only to a long fiber but also to a short fiber provided with mechanical crimping or the like. Next, a fabric is formed using the composite fiber thus obtained. Alternatively, a fabric may be formed after performing a false twisting process or twisting a yarn in order to obtain a specification suitable for the purpose. The form of the fabric may be a woven fabric, a knitted fabric, a nonwoven fabric, or a fibrous structure made of the composite fiber as long as the shape is maintained.

Further, when the cloth is subjected to an alkali treatment, the aliphatic polyester (B) is reduced by 10 to 100% to obtain the polyamide-based composite fiber according to the second aspect.

In the alkali treatment, usually, sodium hydroxide is converted into an aqueous solution of 10 g / l to 50 g / l, and this aqueous solution is heated to a temperature ranging from 60 ° C. to boiling, and a desired function such as texture. The weight is reduced by the time required for the sex to develop. After the alkali-reduced fabric is neutralized, it is dyed and finished to be a product.

[0029]

Next, the present invention will be specifically described based on examples. The measurement and evaluation of various characteristics in the examples were performed by the following methods. (1) Melting point (° C.) Using a differential scanning calorimeter DSC-2 manufactured by PerkinElmer, about 5 mg of a polymer sample, in nitrogen, at a heating rate of 10 ° C. /
Min, hold at 200 ° C for 5 minutes, lower the temperature to 20 ° C at a rate of 10 ° C / min, and again increase the temperature to 200 ° C at a rate of 10 ° C / min.
The maximum melting exothermic peak temperature when the temperature was raised to the melting point was defined as the melting point (hereinafter referred to as Tml). (2) Glass transition temperature (° C.) The initial exothermic peak temperature obtained when measuring the above melting point was defined as the glass transition temperature (hereinafter, referred to as Tg). (3) MFR (g / 10 minutes) It is a value measured at 210 ° C. under a load of 2160 g according to ASTM D1238. (4) Strength and elongation of long fiber According to JIS L-1013, the maximum tensile strength measured at a gripping interval of 30 cm and a tensile speed of 30 cm / min divided by the fineness is defined as the strength. The elongation was determined from the elongation of the sample. (5) Biodegradability After making the fiber into a fabric, it was poured into an aqueous solution (temperature: 80 ° C.) of 10 g / l or 40 g / l of sodium hydroxide and subjected to alkali reduction treatment for an arbitrary treatment time while stirring. Then, after cooling the residual liquid from which the cloth was taken out, the liquid was neutralized with hydrochloric acid, and the released substances such as low molecular weight polymers were removed from a wire mesh # 2.
What was scooped with 40 mesh was sandwiched in the same kind of wire mesh and buried in the ground as it was. Further, it was taken out two years later, and it was examined whether or not a substance such as a released low-molecular-weight polymer was present while maintaining its form. When the substance was not present, it was evaluated that the degradability was good. Example 1 Relative viscosity (measured at a concentration of 1 g / dl in 96% sulfuric acid as a solvent at a temperature of 25 ° C.) of 2.53 and a melting point (Tml) of 215
Melted at 265 ° C. using nylon 6 at a temperature of 265 ° C., having an optical purity of 99%, an MFR of 4 g / 10 min, and a melting point (T
ml) was melted at 260 ° C. using a poly-L lactic acid resin having a temperature of 170 ° C. as a polymer of the B component, and melt spinning was performed at a composite spinning temperature of 265 ° C.

That is, using a compound spinning machine having two single-screw extruder-type melt extruders, a discharge rate of 30 g / min (composite ratio A / B = 50/50 weight ratio), cooled by an air cooling device and wound into two pieces at a spinning speed of 1100 m / min while oiling to obtain an undrawn yarn.

Using this undrawn yarn, drawing was performed using a commonly used multi-stage hot drawing machine capable of hot drawing. That is, the first-stage stretching ratio is 1.01, the second-stage stretching ratio is 3.2, the second roller temperature is 80 ° C., the first and third rollers are not heated, and the second and third rollers are not heated. Drawing was performed at 1000 m / min by contacting a contact type heater heated to 120 ° C. between three rollers to obtain a long fiber having a cross section of 75 denier / 36 filament as shown in FIG. 1 (g). . The obtained long fibers had no adhesion and had a strength of 4.5 g / d and an elongation of 35%.

After the fibers were warped by a single warping machine, they were woven with a plain weave structure by a water jet loom machine. Weaving density: 108 warps / 2.54 cm, weft 9
It was 2 pieces / 2.54 cm, and the woven fabric was tight, stiff, and excellent in repulsion. Using this fabric,
An alkali treatment was performed. The alkali treatment was performed under the conditions of 10 g / l of sodium hydroxide, a temperature of 80 ° C., and 10 minutes.
The woven fabric was taken out, neutralized, washed with water, dried and measured for the weight loss rate. The weight loss rate was 22%, and the weight loss rate of the polymer of the B component was equivalent to 44%.

The obtained fabric after the weight reduction treatment had a texture with a dry feeling. The weft of this woven fabric is unwound and the fiber strength is measured to be 4.4 g / d
And showed almost no decrease in strength. Furthermore, when the biodegradability of the substance released by the neutralization treatment from the waste liquid after the alkali treatment was evaluated, good degradability was shown. Example 2 The woven fabric obtained in Example 1 was subjected to alkaline treatment conditions.
The alkali reduction treatment was performed under the same conditions as in Example 1 except that the sodium hydroxide concentration was 5 g / l and the treatment time was 8 minutes. The weight loss rate of this woven fabric was 10%, and the weight loss rate of the polymer of the component B was 20%. When the obtained woven fabric was dyed with an acid dye at 98 ° C. for 30 minutes, the dyeability was also improved. In addition, when the water absorption properties were examined in accordance with the birec method of JIS-L-1096, it was found that the fabric was excellent in water absorption. The cross section of the single fiber after the alkali weight reduction was an irregular cross section having a gear-like sharp edge, and the texture of the woven fabric had a dry feeling that cannot be obtained with ordinary nylon fibers. Example 3 The woven fabric obtained in Example 1 was subjected to alkaline treatment under the following conditions:
The alkali weight reduction treatment was performed under the same conditions as in Example 1 except that the processing time was changed to 20 minutes. Weight loss rate of this fabric is 50%
And the weight loss rate of the polymer of the component B was equivalent to 100%. That is, a woven fabric was formed in which single fibers were formed of 0.17 denier ultrafine nylon 6 fibers. The obtained woven fabric after the weight loss treatment had a very soft touch feeling. Example 4 230 ° C. using a nylon 6 / nylon 12 copolymer having a relative viscosity of 2.58 and a melting point (T ml) of 160 ° C. as a component A
The poly-L-lactic acid resin having an optical purity of 99%, an MFR of 15 g / 10 min and a melting point (Tml) of 170 ° C. was melted at 230 ° C. as a polymer of the B component, and the composite spinning temperature was 230 ° C. C. and melt spinning was performed.

That is, using a composite spinning machine comprising two single-screw extruder-type melt extruders, a discharge rate of 31 g / min (core / min) from a special core-sheath type composite nozzle having an equivalent diameter of 0.4 mm and 36 holes. The undrawn yarn was wound up at a spinning speed of 1100 m / min while cooling and oiling with an air cooling device.

This undrawn yarn was drawn in the same manner as in Example 1 except that the draw ratio of the second step was changed to 3.5 to obtain a long fiber of 75 denier / 36 filaments.
The obtained long fiber is a special fiber having a core-sheath cross section as shown in FIG.
It had physical properties of 4.1 g / d and an elongation of 38%.

Using this filament, a woven fabric was produced in the same manner as in Example 3 and evaluated.

As a result, the rate of weight loss by the alkali treatment was 5
It was 0%, and the weight loss rate of the core polymer was 100%. The resulting woven fabric after weight reduction is lightweight,
Investigation of the water absorption properties according to the Bilek method of IS-L-1096 revealed that the fabric was excellent in water absorption.

The weft of the woven fabric was unwound and the fiber strength was measured to be 3.5 g / d, indicating that the fiber strength was not significantly reduced. Further, when the waste liquid after the alkali treatment was neutralized and the biodegradability of the substance released was evaluated,
It showed good degradability. Comparative Example 1 The optical purity was 99%, the MFR was 25 g / 10 min,
A polymer consisting of only a poly L-lactic acid resin having a melting point (Tml) of 170 ° C was melted at 220 ° C and spun. That is,
Using a general spinning machine with one single-screw extruder-type melt extruder, the equivalent diameter is 0.4 mm and the number of holes is 36.
Spin at a discharge rate of 33 g / min from the nozzle cap, cool with an air cooling device and spinning speed 1100 m while oiling
/ Min to obtain an undrawn yarn.

Using this undrawn yarn, drawing was carried out in the same manner as in Example 1 except that the draw ratio in the second step was set at 3,1, thereby obtaining a long fiber of 75 denier / 36 filaments.
The obtained long fiber has no adhesion, no thread breakage, and a strength of 3.2 g.
/ D and an elongation of 33%.

Using the obtained long fibers, a woven fabric was formed in the same manner as in Example 1 and evaluated. As a result, the weight reduction rate in the alkali treatment was 40%, and the weft of the obtained woven fabric after the weight reduction treatment was unraveled, and the fiber strength was measured to be only 1.4 g / d, and the fiber strength was remarkably reduced. The woven fabric after the weight reduction treatment was simply not fine and the strength of the woven fabric was merely reduced, and no special functionality was imparted. Comparative Example 2 As the B component, the intrinsic viscosity was 0.7 and the melting point (Tml)
Using a polyester resin obtained by copolymerizing sulfoisophthalic acid at 180 ° C., using the same nylon 6 as in Example 1 for the A component, spinning temperature of 230 ° C., discharge rate of 41 g / min (composite ratio A / B = 70 / 30 weight ratio), cooled with an air cooling device, and oiled to a first roller speed of 360.
A 75 denier / 36 filament long fiber was obtained in the same manner as in Example 1 except that the second roller speed was 3620 m / min, the third roller speed was 5040 m / min, and the third roller temperature was 130 ° C. The obtained long fiber had no adhesion, and had physical properties of a strength of 4.3 g / d and an elongation of 38%.

Next, alkali treatment was carried out in the same manner as in Example 1 except that the concentration of sodium hydroxide was set to 20 g / l, twice that of Example 1, and the treatment time was set to 40 minutes, to obtain a 23% weight loss rate. Was. The obtained woven fabric after the weight loss treatment was slightly less dry than in Example 1, but had a texture almost similar to that of Example 1.

When the weft of the woven fabric was unwound and the fiber strength was measured, it was 4.1 g / d, and the fiber strength did not decrease much.

However, when the biodegradability of the substance released by neutralization from the waste liquid after the alkali treatment was evaluated, no degradability was shown. Comparative Example 3 A polymer consisting of only nylon 6 having a relative viscosity of 2.58 and a melting point (Tml) of 215 ° C. was melted at 265 ° C. and spun. That is, using a general spinning machine with one single-screw extruder-type melt extruder, a discharge amount of 38 g / from a nozzle die having an equivalent hole diameter of 0.4 mm and 36 holes.
The yarn was spun at a spinning speed of 1200 m / min while cooling and oiling with an air cooling device to obtain an undrawn yarn.

Using this undrawn yarn, drawing was carried out using a generally used hot drawing type two-stage drawing machine. That is, the draw ratio of the first step and the draw ratio of the second step are set to 1.02.
And 3.8, 150 between the unheated second and third rollers.
Drawing was performed while contacting with a contact-type heater heated to ℃ to obtain a 75 denier / 36 filament long fiber.
The obtained long fiber has no adhesion, no thread breakage, and a strength of 4.6.
g / d and elongation were 34%. A woven fabric was prepared using the obtained long fibers as in Example 1, and the fabric was evaluated. As a result, it was found that the fabric had little tension and stiffness and lacked resilience. Furthermore, this fabric could not be subjected to alkali weight reduction treatment.

[0045]

According to the present invention, it is biodegradable, has little environmental pollution, has relatively high fiber strength, and has a multifunctional property capable of imparting bulkiness, firmness, waist, dry feeling and water absorption. A polyamide-based composite fiber is provided.

In particular, the polyamide-based composite fiber of the present invention
A fiber that can be environmentally friendly, including waste liquid treatment, by easily reducing the amount of biodegradable polymer components by alkali.Knits, woven fabrics, nonwoven fabrics, and other various fiber structures and composite structures By applying the method to weight reduction treatment, a soft and bulky product can be obtained, which can be suitably used for clothing, household goods, and the like.

Further, the recovered substance contained in the waste liquid of the alkali reduction treatment is completely decomposed and disappears when left in an environment where a large number of microorganisms are present, for example, in soil or water. It is useful, or it can be reused, for example, by composting it into fertilizer, so it is also useful from the viewpoint of resource reuse.

[Brief description of the drawings]

FIGS. 1A to 1K are diagrams showing examples of the cross-sectional shape of a single fiber constituting a polyamide-based composite fiber of the present invention.

Continued on the front page F term (reference) 4L041 AA07 AA15 AA19 AA20 BA02 BA03 BA04 BA05 BA09 BA11 BA12 BA21 BA23 BA38 BC02 BC20 BD11 CA05 CA15 CA21 CA28 DD01 DD05 DD14 EE06 EE15

Claims (3)

[Claims] 1. A composite fiber comprising a polyamide polymer (A) and an aliphatic polyester (B), wherein the composite ratio (A / B) is 5/95 to 95/5 and the aliphatic polyester is A polyamide-based composite fiber, wherein (B) is disposed so as to be exposed at least on a part of the fiber surface. 2. A polyamide-based conjugate fiber in which the aliphatic polyester (B) is reduced by 10 to 100% from the conjugate fiber according to claim 1. 3. The aliphatic polyester is a polylactic acid-based polymer, wherein poly (D-lactic acid), poly (L-lactic acid),
Selected from the group consisting of D-lactic acid and L-lactic acid or a polymer of an optical isomer obtained by blending them, a copolymer of D-lactic acid and hydroxycarboxylic acid, and a copolymer of L-lactic acid and hydroxycarboxylic acid The polyamide-based conjugate fiber according to claim 1 or 2, which is a blended polymer or a blend thereof.