TW202113178A - Polyamide composite fiber and finished yarn - Google Patents

Abstract

The present invention addresses the problem of providing a polyamide composite fiber obtained from a woven or knitted fabric having excellent stretchability or a finished yarn comprising the same. This polyamide composite fiber is an eccentric core-in-sheath type of polyamide composite fiber comprising two kinds of crystalline polyamide (A) and crystalline polyamide (B) differing in composition from each other, wherein the water absorptivity and thermal contraction stress of the polyamide composite fiber after being left to stand still for 72 hours in an environment in which the temperature is 30 DEG C and the relative humidity is 90 RH% are 5.0% or less and 0.15 cN/dtex or more, respectively.

Description

Polyamide composite fiber and processed yarn

The present invention relates to an eccentric core-sheath composite fiber composed of polyamide and a processed yarn composed thereof.

Since conventionally, polyamide fibers are softer than polyester fibers and have a good touch, and are widely used in clothing applications. A single fiber thread composed of a single type of polymer, such as nylon 6 or nylon 66, which is representative of polyamide fibers for clothing. The fiber itself has almost no stretchability. Therefore, it is subjected to false twist processing to impart stretchability and is used in Use of stretchable braid. However, it is still difficult to obtain a braided fabric with sufficient stretchability for such a single-fiber yarn subjected to false-twist processing or the like.

Therefore, it is proposed to obtain a stretchable woven fabric by using elastic fibers, or to combine two polymers with different properties to create a latent roll that exhibits crimping by heat treatment using a dyeing step, etc. A method to obtain a stretchable woven fabric by shrinking composite fibers with shrinkage properties (refer to Patent Document 1). Furthermore, as a polyamide composite fiber with potential crimping properties, a composite fiber in which two types of polyamides with poor viscosity are arranged as a side-by-side type or an eccentric core-sheath type is also proposed (see Patent Document 2).

In addition, a composite fiber and processed yarn is proposed by making a highly heat-shrinkable polyamide composite fiber containing amorphous polyamide or a processed yarn composed of it, even if high tension is applied in the warp direction. In the state of wet heat or dry heat treatment, the braid still shrinks under a stress higher than the restraining force of the braid, and can exhibit crimping properties in the warp direction (see Patent Document 3). [Prior Technical Literature] [Patent Literature]

Patent Document 1: International Patent Publication No. 2018/110523 Patent Document 2: Japanese Patent Laid-Open No. 2002-363827 Patent Document 3: International Patent Publication No. 2017/221713

(The problem to be solved by the invention)

However, when the composite fiber described in Patent Document 1 is obtained from two types of polyamides with different properties, due to the unique swelling properties of polyamides, the stretchability is lost due to processing steps such as scouring steps or dyeing steps. The case where the product cannot obtain sufficient stretchability. In addition, the polyamide composite fiber described in Patent Document 2 is also the same.

Furthermore, the composite fiber composed of polyamide described in Patent Document 2 has excellent crimping properties even in the state of raw yarn or processed yarn, and is easy to be used in the damp and heat step of scouring or dyeing of knitted fabrics. Wrinkles peculiar to polyamide fibers occur, or it is difficult to remove the wrinkles generated in the moist heat step in the dry heat step of the heat setting step. Therefore, in order to maintain the quality of the knitted fabric, it is necessary to apply tension to the knitted fabric during the moist heat step. , While processing. In this way, in the polyamide composite fiber described in Patent Document 2, tension is applied to the braid in the moist heat step, so that the crimping of the raw yarn or the processed yarn cannot be fully expressed, and as a result, it becomes a braid that lacks stretchability. Subject.

In addition, in the highly heat-shrinkable polyamide composite fiber described in Patent Document 3, since the amorphous polyamide polymer undergoes moisture absorption and crystallization with time, the shrinkage characteristics also decrease with time, which may result in low stretchability. The situation of the braid.

Therefore, the object of the present invention is to solve the above-mentioned problems and provide a polyamide composite fiber that can obtain a braid with superior stretchability and a processed yarn formed therefrom. (Technical means to solve the problem)

The polyamide composite fiber of the present invention is an eccentric core sheath type polyamide composite fiber composed of two types of crystalline polyamide (A) and crystalline polyamide (B) with different compositions, wherein, The water absorption rate of the polyamide composite fiber after being allowed to stand for 72 hours in an environment with a temperature of 30° C. and a relative humidity of 90 RH% is 5.0% or less, and the heat shrinkage stress is 0.15 cN/dtex or more. According to a preferred aspect of the polyamide composite fiber of the present invention, the rigid amorphous content of the polyamide composite fiber is 40-60%, and the stretch elongation is more than 30%. According to a preferred aspect of the polyamide composite fiber of the present invention, the crystalline polyamide (A) is nylon 6 or its copolymer. According to a preferred aspect of the polyamide composite fiber of the present invention, the crystalline polyamide (B) is nylon 610 or its copolymer. According to a preferred aspect of the polyamide composite fiber of the present invention, the crystalline polyamide (A) is the core component, and the crystalline polyamide (B) is the sheath component. In the present invention, a processed yarn composed of the above-mentioned polyamide composite fiber can be obtained. According to a preferred aspect of the above-mentioned processed yarn of the present invention, the stretch elongation rate is 100% or more. (Compared with the effect of previous technology)

According to the present invention, it is possible to obtain polyamide composite fibers and processed yarns capable of producing woven fabrics with superior stretchability. Furthermore, according to the present invention, even if wet heat or dry heat is applied under high tension in the warp direction, it can still shrink under a stress higher than the binding force of the braid, and can fully express the warp direction Crimping property, can produce polyamide composite fiber and processed yarn of braided fabric with superior stretchability.

Hereinafter, the polyamide composite fiber of the present invention and the processed yarn using the same will be described. In addition, in this manual, "mass" is synonymous with "weight".

The polyamide composite fiber of the present invention is an eccentric core sheath type polyamide composite fiber composed of two different polymer compositions of crystalline polyamide (A) and crystalline polyamide (B) , It is characterized in that the water absorption rate of the polyamide composite fiber after standing for 72 hours in an environment with a temperature of 30°C and a relative humidity of 90RH% is 5.0% or less, and the heat shrinkage stress is 0.15cN/dtex or more.

The polyamide composite fiber of the present invention is an eccentric core-sheath type composite fiber composed of two types of crystalline polyamide (A) and crystalline polyamide (B) with different polymer compositions. The so-called eccentric core-sheath type polyamide composite fiber refers to a composite fiber in which two or more types of polyamide form an eccentric core-sheath structure.

The polyamide composite fiber of the present invention must have a composite profile formed by joining two types of crystalline polyamides, and the two types of crystalline polyamides whose polymer compositions are different from each other are not substantially separated and depend on the joining state. exist. In the present invention, it is preferable to use crystalline polyamide (A) as the core component, crystalline polyamide (B) as the sheath component, and cover the crystalline polyamide (A) with the crystalline polyamide (B). ) The eccentric core sheath type.

Here, the term eccentric in the present invention means that in the cross section of the polyamide composite fiber, the position of the center of gravity of the core component is different from the center of the cross section of the composite fiber.

Fig. 1 is a schematic cross-sectional view illustrating the cross-section of the eccentric core-sheath type polyamide composite fiber (hereinafter also referred to as "polyamide eccentric core-sheath composite fiber") of the present invention. In Figure 1, the polyamide eccentric core sheath type composite fiber 10A is composed of a core component (crystalline polyamide (A)) 1 and a sheath component (crystalline polyamide (B)) 2, which is one of the core components. The position of the center of gravity of the crystalline polyamide (A) is different from the center of the cross section of the composite fiber.

2(A) to 2(C) are schematic cross-sectional views illustrating the cross-section of another polyamide eccentric core sheath type composite fiber of the present invention. Figure 2 (A), Figure 2 (B) and Figure 2 (C) respectively show the core component (crystalline polyamide (A)) 1 and sheath component (crystalline polyamide (B)) of the eccentric core sheath type 2 The state of the polyamide eccentric core sheath type composite fiber 10B~10C with different shapes and arrangements is the same as in Fig. 1, the position of the center of gravity of the crystalline polyamide (A) belonging to the core component and the cross-section of the composite fiber The center is different.

In addition, the composite ratio of crystalline polyamide (A) and crystalline polyamide (B) is based on crystalline polyamide (A): crystalline polyamide (B)=6:4~4:6 (Mass ratio) is a better aspect. By setting the quality to be 6:4~4:6 in this way, the water absorption rate of the polyamide composite fiber of the present invention can be controlled below 5.0%, and the obtained braid can be given superior stretchability .

The polyamide composite fiber of the present invention is composed of two types of crystalline polyamide whose polymer composition is different from each other. Crystalline polyamide, that is, polyamide that forms crystals and has a melting point, is a polymer in which a hydrocarbon group is linked to the main chain via an amide bond. Specific examples of the crystalline polyamide include polyhexamethylene amide, polyhexamethylene hexamethylene diamide, poly sebacic hexamethylene diamine, polytetramethylene hexamethylene diamide, 1,4-cyclohexane Condensation polymerization type polyamides of alkane bis (methylamine) and linear aliphatic dicarboxylic acids, etc., and these copolymers or mixtures of these, etc. Among them, from the viewpoint of easily reproducing a uniform system and exhibiting a stable function, it is preferable to use a homogenous polyamide.

The crystalline polyamide (A) includes, for example, nylon 6, nylon 66, nylon 4, nylon 610, nylon 11, nylon 12, etc., and copolymers containing these as the main component. The system is compatible with crystalline polyamide ( B) Different kinds of polyamides. The crystalline polyamide (A) can contain components other than lactamine, aminocarboxylic acid, diamine, and dicarboxylic acid in its repeating structure without impairing the effect of the present invention. Among them, in terms of yarn-manufacturing properties or strength, elastomers containing polyols and the like in the repeating structure are excluded.

In addition, from the viewpoint of yarn production, strength and peel resistance, it is preferable that more than 90% of the repetitive structure of the crystalline polyamide (A) is made into a single internal amide, amino carboxylic acid or a single combination The polymer of diamine and dicarboxylic acid is more preferably more than 95% of the repeating structure. From the viewpoint of thermal stability, nylon 6 or its copolymer is particularly preferred for such components.

In addition, the crystalline polyamide (B) can be obtained, for example, by a combination of a dicarboxylic acid unit and a diamine unit having a sebacic acid unit as a main component. Among these, it is best to use nylon 610 and its copolymers, which have stable polymerizability, less yellowing of the crimped yarn, and good dyeability. Here, sebacic acid can be produced by refining castor oil seeds, for example, and is positioned as a plant-derived raw material.

Examples of dicarboxylic acids constituting dicarboxylic acid units other than sebacic acid units include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and phthalic acid. Acid, isophthalic acid, and terephthalic acid, etc., can be adjusted within a range that does not impair the effect of the present invention.

Furthermore, with regard to these dicarboxylic acids, plant-derived dicarboxylic acids are preferred. As the copolymerization amount of the dicarboxylic acid units other than the sebacic acid unit, the total dicarboxylic acid unit is preferably 0-40 mol%, more preferably 0-20 mol%, and still more preferably 0~ 10 mol%.

Examples of the diamine constituting the diamine unit include diamines with 2 or more carbon atoms, preferably diamines with 4 to 12 carbon atoms; specifically, butane diamine, 1,5-pentanediamine, Hexamethylene diamine, trimethylene diamine, nonane diamine, methyl pentane diamine, phenylenediamine, ethambutol, etc. Furthermore, with regard to these diamines, plant-derived diamines are preferred.

In addition, if necessary, pigments, heat stabilizers, antioxidants, weathering agents, flame retardants, plasticizers, mold release agents, and lubricants can be added to the crystalline polyamide (A) and crystalline polyamide (B). Agent, foaming agent, antistatic agent, moldability improver, and strengthening agent.

The polyamide composite fiber of the present invention is at a temperature of 30°C and a relative humidity of 90RH% (temperature of 30°C×relative humidity of 90RH%), and the water absorption rate after standing for 72 hours must be below 5.0%. The water absorption here refers to the value measured in accordance with JIS L 1013. By setting the water absorption rate under the temperature of 30℃×relative humidity 90RH% for 72 hours to be 5.0% or less, the swelling of the polyamide fiber under the moist heat conditions such as the scouring step or the dyeing processing step will be small. The stretch of the braid becomes smaller. Thereby, it is possible to perform steps such as a scouring step or a dyeing step without applying excess tension to the knitted fabric. As a result, a knitted fabric with superior stretchability can be obtained.

In contrast, the higher the water absorption rate, the polyamide fiber tends to swell due to water content. If the water absorption rate exceeds 5.0%, wrinkles or grains are likely to occur in the scouring or relaxation treatment step and the dyeing step. Generally, the stretchability decreases due to the stretching process.

The water absorption rate is preferably 4% or less. In addition, the lower limit of the water absorption rate is not specified, but it is about 1.0% in practice.

The water absorption rate can be controlled by the polymer selection of crystalline polyamide (A) and crystalline polyamide (B) and the core-sheath composite ratio.

The polyamide composite fiber of the present invention must have a heat shrinkage stress of 0.15 cN/dtex or more. The term "heat shrinkage stress" here refers to the use of a heat shrinkage stress measuring machine (for example, Kanebo Engineering, type "KE-2") to connect the measured fiber strands into a ring with a circumference of 16 cm and apply the strands The initial load of 1/30g of the fineness (dectex) is measured from 40°C to 210°C at a heating rate of 100°C/min. The peak value of the obtained thermal stress curve is measured as the maximum thermal stress (cN/ dtex).

By setting the heat shrinkage stress to 0.15cN/dtex or more, even if wet heat treatment or dry heat treatment is performed under high tension in the warp direction, the braid will still shrink under a stress higher than the binding force of the braid. The crimping property is fully exhibited in the warp direction, and a knitted fabric with good stretchability can be obtained. When the heat shrinkage stress is less than 0.15 cN/dtex, in the moist heat step where high tension is applied, sufficient crimping is not exhibited, resulting in a knitted fabric with degraded stretchability.

The thermal shrinkage stress is preferably 0.20 cN/dtex or more, more preferably 0.25 cN/dtex or more. In addition, if the heat shrinkage stress is too high, the meshes at the interlaced points of the fabric are likely to be clogged, which hinders stretchability. Therefore, the upper limit of the heat shrinkage stress is preferably 0.50 cN/dtex. The thermal shrinkage stress can be controlled by using a high-viscosity polymer, and then controlling the rigidity and amorphous content of the fiber according to the thermal extension conditions of low spinning temperature and low spinning speed and high elongation ratio.

The polyamide composite fiber of the present invention preferably has a rigid amorphous content of 40-60%. The so-called rigid amorphous (Rigid amorphous) is obtained by the method described in the item of the examples to obtain the amount of amorphous, which is an intermediate state between crystalline and mobile amorphous (Mobile amorphous; conventionally completely amorphous), even if it is The molecular motion freezes above the glass transition temperature (Tg), and becomes amorphous in a fluid state at a temperature higher than Tg (for example, refer to Minoru Toshi, "DSC (3)-Glass Transition Behavior of Polymers -", The Society of Fiber Science and Technology) Chi (Fiber and Industry), Vol.65, No.10 (2009)).

The amount of rigid amorphous is represented by "100%-degree of crystallinity-amount of movable amorphous". In the present invention, the polyamide composite fiber includes a crystal part, a rigid amorphous part, and a movable amorphous part. The thermal shrinkage stress depends on the binding force of the rigid amorphous chain when the fiber structure is formed, and the shrinkage of the amorphous chain that has mobility when heat treatment is performed. By setting the amount of rigid amorphous to the above range, thermal shrinkage stress can be expressed.

The amount of rigid amorphous can be controlled by spinning. The amount of rigid amorphous is the same as the thermal shrinkage stress, and can be controlled by using high-viscosity polymers and the design of the manufacturing method.

With a rigid amorphous content of more than 40%, the restraining force of the rigid amorphous chain is exhibited, and the shrinkage of the movable amorphous chain is not impaired, and the required thermal shrinkage stress can be obtained. In addition, when the amount of rigid amorphous is 60% or less, the restraining force of the rigid amorphous chain is expressed, the shrinking force of the movable amorphous chain can be maintained, and the required thermal shrinkage stress can be obtained. The amount of rigid amorphous is preferably 45-55%.

The polyamide composite fiber of the present invention preferably has a stretch elongation of 30% or more. The so-called stretch elongation refers to the index of the crimpability of the raw yarn, and the higher the value, the higher the crimp performance ability.

The polyamide composite fiber of the present invention exhibits poor shrinkage and crimp due to the poor alignment of crystalline polyamide (A) and crystalline polyamide (B) when forming fibers. However, in general, polyamide fibers are prone to wrinkles during the scouring or dyeing process of the knitted fabric. In order to maintain the quality of the knitted fabric, it is processed under high tension in the warp direction. The possibility of shrinkage difference being reduced due to the influence of external force (high tension). In order to maintain this difference in shrinkage, the original yarn has a certain thermal shrinkage stress to maintain the original yarn's crimpability. If the stretch elongation is more than 30%, a knitted fabric with better stretchability can be obtained. The stretch elongation is more preferably 100~200%. The stretch elongation is expressed by the difference in shrinkage between the two components of the crystalline polyamide (A) and the crystalline polyamide (B), so the larger the difference in shrinkage, the higher the stretch elongation.

The polyamide composite fiber of the present invention preferably has a total fineness of 20-120 dtex as a thread. Especially when it is used for sportswear, down jackets, outerwear and underwear, the total fineness is more preferably 30~90dtex. In addition, the single fiber fineness of the polyamide composite fiber is not specified, and it is usually used in the range of 1.0 to 5.0 dtex.

Next, the manufacturing method of the polyamide composite fiber of the present invention by melt spinning will be described. Among the crystalline polyamides used in the present invention, the relative viscosity of the crystalline polyamides (A) is preferably set to 3.1 to 3.8. In addition, the relative viscosity of the crystalline polyamide (B) is preferably set to 2.6 to 2.8. The relative viscosity ratio (A/B) of the crystalline polyamide (A) and the crystalline polyamide (B) is preferably set to 1.2 to 1.4.

By selecting a crystalline polyamide with a relative viscosity in this range, it exhibits poor shrinkage after heat treatment, forming a three-dimensional spiral structure and exhibiting crimping. In addition, in the spinning step, the polyamide is transferred from amorphous to crystalline by receiving the heat of fusion. At this time, because the crystalline polyamide (A) with a higher relative viscosity has a higher molecular binding force, the speed of its transition from amorphous to crystalline is also slower than that of the crystalline polyamide (B) with a lower relative viscosity. . Therefore, after the spinning nozzle is ejected, if the polyamide is cooled during the transition from amorphous to crystalline, it is easy to form an intermediate state of rigid amorphous, and the amount of rigid amorphous of the composite fiber increases, which increases the thermal contraction stress and stretching elongation rate.

In addition, the polyamide composite fiber of the present invention has a composite cross-section formed by joining two kinds of crystalline polyamides, and the crystalline polyamide (A) which belongs to the core component is divided into the crystalline polyamide which belongs to the sheath component. Amine (B) coated eccentric core sheath structure. In the case of the conventional side-by-side structure in which the crystalline polyamide (A) is not covered with the crystalline polyamide (B) which is a sheath component, the above-mentioned crystalline polyamides with poor relative viscosity are respectively melted and combined A composite cross-section is formed in the spinning unit, and the polymer flow resistance is different when it is discharged from the spinning nozzle. Due to the poor flow speed, the yarn is likely to bend and the workability is deteriorated. Therefore, in the production of crystalline polyamide (A) and crystalline polyamide (B) with poor melt viscosity, the eccentric core-sheath structure of the present invention can be used for stable production with usual equipment.

Next, the manufacturing method of the polyamide composite fiber of the present invention by melt spinning and composite spinning will be described.

First, the manufacturing method of the polyamide composite fiber of the present invention by high-speed direct spinning by melt spinning is illustrated as follows. Melt crystalline polyamide (A) and crystalline polyamide (B) separately, use a gear pump to measure and transport, and directly form a composite flow in a core-sheath structure by the usual method, using an eccentric core-sheath type The spinning nozzle for the composite fiber is ejected from the spinning nozzle in such a way that it becomes the cross section illustrated in FIG. 1. The discharged polyamide composite fiber thread is blown against cooling air by a chimney type or other thread cooling device to be cooled to 30°C. Then, the cooled thread is fed and bundled by the oil feeding device, and is drawn by the drawing roller at 1500~4000m/min, and then passed through the drawing roller and the stretching roller. At this time, according to the drawing roller and the drawing roller. The ratio of the peripheral speed of the stretching roller is 1.5~3.0 times for stretching. Furthermore, the thread is heat-set by a stretching roller, and is wound into a package at a winding speed of 3000m/min or more.

In addition, the manufacturing method of the polyamide composite fiber of the present invention by high-speed direct spinning by melt spinning is exemplified and explained as follows. Melt crystalline polyamide (A) and crystalline polyamide (B) separately, use a gear pump to measure and transport, and directly form a composite flow in a core-sheath structure by the usual method, using an eccentric core-sheath type The spinning nozzle for the composite fiber is ejected from the spinning nozzle in such a way that it becomes the cross section illustrated in FIG. 1. The discharged polyamide composite fiber thread is blown against cooling air by a chimney type or other thread cooling device to be cooled to 30°C. Then, the cooled thread is fed and bundled by the oil feeding device, and is drawn by the drawing roller at 3000~4500m/min, so that it passes through the drawing roller and the stretching roller. At this time, according to the drawing roller and the drawing roller. The ratio of the peripheral speed of the stretching roller is 1.0~1.2 times for micro-stretching. Furthermore, the yarn is wound into a package at a winding speed of 3000 m/min or more.

In particular, the spinning temperature is appropriately designed based on the melting point of the crystalline polyamide (A), which has a relatively high relative viscosity. When the spinning temperature becomes higher, the crystalline portion increases and the amount of rigid amorphous material decreases. When the spinning temperature becomes lower, the amount of movable amorphous material increases and the amount of rigid amorphous material tends to slightly decrease. Therefore, the spinning temperature is preferably 35 to 70°C higher than the melting point of the crystalline polyamide (A), and more preferably 45 to 60°C higher. By appropriately setting the spinning temperature, the rigid amorphous content of the polyamide composite fiber of the present invention can be controlled, and the required thermal contraction stress and stretching elongation can be obtained.

In addition, by appropriately designing the traction extension (drawing speed), the rigid amorphous content of the polyamide composite fiber of the present invention is increased, and the thermal shrinkage stress and the stretching elongation rate are improved. The drawing speed is preferably 1500~4000m/min.

In the case of obtaining a stretched yarn, by using a drawing roll as a heating roll to perform thermal extension, the rigidity and amorphous content of the polyamide composite fiber of the present invention increases, and the thermal shrinkage stress increases. The stretching ratio is preferably 1.5 to 3.0 times, more preferably 2.0 to 3.0 times. In addition, the thermal extension temperature is preferably 30 to 90°C, more preferably 40 to 60°C.

In addition, the heat shrinkage stress of the polyamide composite fiber of the present invention can be appropriately designed by using the stretching roller as the heating roller to perform heat setting. The heat setting temperature is preferably 130 to 180°C.

In addition, a known interleaving device may be used in the steps up to winding, and interleaving may also be performed. If necessary, the number of interlaces can be increased by adding a plurality of interlaces. Furthermore, before winding up, an oil agent may be added additionally.

The processed yarn composed of the polyamide composite fiber of the present invention uses the eccentric core sheath type polyamide composite fiber of the present invention for at least a part of the thread. The manufacturing method of the processed yarn is not limited, and if exemplified, for example, a blended fiber method or a false twist processing method can be mentioned. As the fiber blending method, air blending, twisting, composite false twisting, etc. can be used. Air blending can easily control the blending and has a low manufacturing cost, so it can be preferably used. As a false twist processing method, it is preferable to perform false twist using a needle type, a friction type, a belt type, etc. according to the fineness or the number of twists.

The processed yarn composed of the polyamide composite fiber of the present invention preferably has a stretch elongation of 100% or more. By setting the stretch elongation to 100% or more, the sufficient crimping performance and the crimping of the false twisted yarn are multiplied by each other, and a knitted fabric with superior stretchability is obtained. The higher the stretch elongation, the more the crimpability increases, but processing wrinkles are more likely to occur. In order to suppress wrinkles, manufacturing with high tension in the warp direction will easily hinder the stretchability of the knitted fabric, so it is better. The tensile elongation of the sample system is 120~200%.

The processed yarn composed of the polyamide composite fiber of the present invention preferably has a stretch elongation of 100% or more as described above. The stretch-knitted fabric is constructed by using the polyamide composite fiber or processed yarn of the present invention in at least a part. According to the present invention, even when high tension is applied to the warp direction in the moist heat step, crimping can be sufficiently exhibited, and a knitted fabric with superior stretchability can be provided.

The stretched and stretched knitted fabric composed of the polyamide composite fiber or processed yarn of the present invention can be woven and knitted according to a known method. In addition, the structure of the knitted fabric is not limited.

In the case of fabrics, the weave can be a plain weave, a twill weave, a satin weave, or any of these altered weaves, and a mixed weave depending on the purpose used. In order to obtain a fabric with a clear texture and a fluffy feel, it is preferable to use a plain weave with many restraint points, or a ripstop weave that combines a plain weave and a stone weave, and then a basket weave.

In the case of knitting, the organization depends on the purpose used. It can be flat stitch, double rib weave, semi weave of warp knitted fabric, satin weave, jacquard texture, or other changes of the weave, and Any one of the mixed structure; from the viewpoint of thinner knitting, stability, and excellent elongation, the semi-structured structure of single tricot knitting is preferable.

In addition, the use of the knitted fabric composed of the polyamide composite fiber or processed yarn of the present invention is not limited, and it is preferably for clothing use, and more preferably for sports and leisure such as down jackets, windbreakers, golf apparel, raincoats, etc. For clothing or women's clothing for gentlemen. It is especially suitable for sportswear and down jackets. [Example]

Next, examples are given to specifically illustrate the polyamide composite fiber and processed yarn of the present invention.

A. Melting point Thermal analysis was performed using Q1000 manufactured by TA Instruments, and data processing was performed using Universal Analysis2000. Thermal analysis is performed under nitrogen flow (50mL/min), and the measurement is carried out according to the temperature range -50~300℃, the heating rate is 10℃/min, and the mass of the fragment sample is about 5g (the caloric data is standardized by the mass after the measurement). The melting point is determined from the melting peak.

B. Relative viscosity Dissolve 0.25 g of a sample of polyamide fragments in 25 ml of sulfuric acid with a concentration of 98% by mass so as to become 1 g/100 ml, and measure the flow time (T1) at a temperature of 25° C. using an Oswath type viscometer. Next, the downtime (T2) of only sulfuric acid with a concentration of 98% by mass was measured. Let the ratio of T1 to T2, that is, T1/T2, be the relative viscosity of sulfuric acid.

C. Total fineness According to JIS L1013. The fiber sample is made with a tension of 1/30 (g) using a length measuring machine with a frame circumference of 1.125m to make 200 turns of hank yarn. Dry at 105°C for 60 minutes and move it to a dryer. Let it cool for 30 minutes in an environment with a temperature of 20°C and a relative humidity of 55%RH. Measure the hank weight, calculate the mass per 10000m from the obtained value, and determine it. The moisture regain was set to 4.5%, and the total fineness of the fiber thread was calculated. The measurement system was performed 5 times, and the average value was taken as the total fineness.

D. Thermal shrinkage stress Using the KE-2 heat shrinkage stress measuring machine manufactured by Kanebo Engineering, connect the fiber sample into a ring with a circumference of 16 cm, apply an initial load of 1/30 g of the total fineness of the thread, and measure the temperature from 40°C to 100°C/min. The load when the temperature is changed to 210°C, and the peak value of the obtained thermal stress curve is set as the thermal shrinkage stress.

E. Stretching elongation The hank was wound on the fiber sample, immersed in boiling water at 90°C for 20 minutes and then air-dried. A load of 2 mg/d was applied for 30 seconds to obtain the length A, and then a load of 100 mg/d was applied for 30 seconds to obtain the length B. Calculate the expansion and contraction elongation according to the following formula. Stretching elongation (%)=〔(B-A)/B〕×100

F. Rigid amorphous quantity The amount of rigid amorphous was measured using Q1000 manufactured by TA Instruments as a measuring device. Use the difference (△Hm-△Hc) between the heat of fusion (△Hm) and the heat of cold crystallization (△Hc) obtained by differential scanning calorimetry (hereinafter referred to as DSC), and the specific heat difference ( △Cp), and then use the theoretical value that the polyamide is 100% crystalline (completely crystalline) and the theoretical value that the polyamide is 100% amorphous (completely amorphous). Here, ΔHm0 is the heat of fusion of polyamide (completely crystallized). In addition, ΔCp0 is the specific heat difference before and after the glass transition temperature (Tg) of polyamide (completely amorphous). According to the following formulas (1) and (2), the degree of crystallinity (Xc) and the amount of movable amorphous (Xma) are obtained. Furthermore, the amount of rigid amorphous (Xra) was calculated by the following formula (3). In addition, the amount of rigid amorphous is calculated from the average value of 2 times of these measurements. (1) Xc(%)=(△Hm-△Hc)/△Hm0×100 (2) Xma(%)=△Cp/△Cp0×100 (3) Xra(%)=100-(Xc+Xma)

The measurement conditions of DSC and temperature-modulated DSC are shown below. (DSC measurement) Measuring device: Q1000 manufactured by TA Instruments Data processing: Universal Analysis2000 manufactured by TA Instruments Environment: Nitrogen flow (50mL/min) Sample amount: about 10mg Sample container: aluminum standard container Temperature and heat correction: high purity indium (Tm=156.61℃, △Hm=28.71J/g) Temperature range: about -50~300℃ Heating rate: 10℃/min The first heating process (first run) (Measurement by temperature-modulated DSC) Measuring device: Q1000 manufactured by TA Instruments Data processing: Universal Analysis2000 manufactured by TA Instruments Environment: Nitrogen flow (50mL/min) Sample amount: about 5mg Sample container: aluminum standard container Temperature and heat correction: high purity indium (Tm=156.61℃, △Hm=28.71J/g) Temperature range: about -50~210℃ Heating rate: 2℃/min

G. Strength and elongation The fiber sample was measured by using "TENSILON" (registered trademark) and UCT-100 manufactured by ORIENTEC, in accordance with the constant-rate elongation conditions shown in JIS L1013 (Testing Methods for Chemical Fiber Yarns, 2010). The elongation is obtained from the elongation at the point of maximum strength in the tensile strength-extension curve. In addition, the strength is the value obtained by dividing the maximum strength by the fineness as strength. The measurement system was performed 10 times, and the average value was taken as the strength and the elongation.

H. Water absorption in an environment with a temperature of 30℃ and a relative humidity of 90RH% According to JIS-L-1013 (2010 edition), the mass is measured after standing for 72 hours in an absolute dry state, at a temperature of 30°C and a relative humidity of 90RH%, to determine its moisture regain.

I. Fabric evaluation (a) Manufacture of weft Polycaprolactam (N6) (relative viscosity 2.70, melting point 222°C) is used, and a spinning nozzle with 12 spinning nozzle discharge holes is used to perform melt discharge at a temperature of 275°C. After melting and spitting out, the resulting thread is cooled, oiled and interlaced, and then drawn by a 2570m/min drawing roll, then stretched to 1.7 times and then heat-fixed at a temperature of 155°C, depending on the winding speed of 4000m/min A nylon 6 yarn with 70 dtex12 monofilament was obtained.

(b) Fabrication of fabrics The eccentric core sheath polyamide composite yarns obtained in Examples 4 to 11 and Comparative Examples 1 to 3 are used as warp yarns (warp density 90 yarns/2.54 cm), and the above (a) is obtained Nylon 6 thread is used for weft (weft density 90/2.54cm), weaving flat fabric (warp/composite fiber) (apparent density 40g/cm ² ). In addition, the eccentric core sheath polyamide composite false-twisted yarn obtained in Examples 1 to 3 was used as the warp (warp density 90 yarns/2.54 cm), and the nylon 6 yarn obtained in (a) was used as the weft ( The weft density is 90 yarns/2.54cm), and the plain fabric (warp/processed yarn) is woven (apparent density 40g/cm ² ). The obtained fabric was subjected to scouring for 20 minutes at a temperature of 80°C, then adjusted to pH 4 with Kayanol Yellow N5G 1% owf and acetic acid, and then dyed at a temperature of 100°C for 30 minutes, and then subjected to a temperature of 80°C for 20 minutes Fixation (Fix) treatment, and finally heat treatment at 170°C for 30 seconds in order to improve the texture.

(c) The elongation in the warp direction of the fabric (stretchability) Using a tensile testing machine, measure the 50mm×300mm wide fabric samples obtained in Examples 1-10 and Comparative Examples 1 to 4, with a grasping interval of 200mm in the direction of the warp of the fabric, and a tensile speed of 200mm/min. The elongation at 14.7N is evaluated according to the following three stages "A", "B" and "C". 15% or more is judged to be stretchable. A (good): more than 20% B (possible): 15% or more and less than 20% C (not possible): less than 15%

[Example 1] Nylon 6 (N6) with a relative viscosity of 3.3 and a melting point of 222°C was used as the crystalline polyamide (A), and nylon 610 (N610) with a relative viscosity of 2.7 and a melting point of 225°C was used as the crystalline polyamide (B). The crystalline polyamide (A) is used as the core component, and the crystalline polyamide (B) is used as the sheath component. They are melted separately, and an eccentric core sheath type composite fiber spinning nozzle (12 holes, round holes) is used to combine The composite ratio (mass ratio) of crystalline polyamide (A) and crystalline polyamide (B) is set as crystalline polyamide (A): crystalline polyamide (B) = 5: 5 for melt discharge (Spinning temperature 270°C). The thread spit out from the spinning nozzle is cooled and solidified by the thread cooling device. After the oil device is supplied with the water-containing oil agent, the fluid interlacing nozzle device is used to interweave, and then the draw roll (room temperature 25℃) ) It is drawn at 3700m/min, and after stretching is 1.1 times between stretching rolls (room temperature 25℃), it is wound into a package at a winding speed of 4000m/min. A polyamide composite fiber yarn with 62 dtex 12 monofilament, 49% stretch elongation, 3.8% water absorption, 0.16 cN/dtex thermal shrinkage stress, and 41% rigid amorphous content was obtained. Using the obtained polyamide composite fiber yarn, according to the state of applying 1.25 elongation ratio by the heater temperature of 190℃, under the condition of twist number (D/Y) 1.95, perform disc-type false twisting to obtain the stretch elongation 130% false twisted processed yarn. The resulting false twisted processed yarn is used as the warp to form a fabric. The resulting fabric has excellent stretchability. The results are shown in Table 1.

[Example 2] Except that nylon 6 (N6) with a relative viscosity of 3.6 and a melting point of 222°C was used as the crystalline polyamide (A), the same method as in Example 1 was followed to obtain a 62dtex12 monofilament, a stretch elongation rate of 53%, and a water absorption rate of 3.8 %, heat shrinkage stress 0.21cN/dtex, 46% rigid amorphous polyamide composite fiber yarn. The obtained polyamide composite fiber yarn was subjected to disk false twist in the same method as in Example 1, to obtain a false twisted processed yarn with a stretch elongation of 150%. The resulting false twisted processed yarn is used as the warp to form a fabric. The resulting fabric has excellent stretchability. The results are shown in Table 1.

[Example 3] Except that a copolymer of nylon 6 and nylon 66 (N6/N66) with a relative viscosity of 3.6 and a melting point of 200°C was used as the crystalline polyamide (A), the same method as in Example 1 was followed to obtain 62dtex12 monofilament, Polyamide composite fiber yarn with 67% stretch elongation, 3.6% water absorption, 0.25cN/dtex thermal shrinkage stress, and 53% rigid amorphous content. The obtained polyamide composite fiber yarn was subjected to disk false twist in the same method as in Example 1, to obtain a false twisted processed yarn with a stretch elongation of 200%. The resulting false twisted processed yarn is used as the warp to form a fabric. The obtained fabric has better stretchability than that of Example 1 and Example 2. The results are shown in Table 1.

[Table 1] Example 1 Example 2 Example 3 Crystalline polyamide A component (core) N6 N6 N6/N66 Crystalline polyamide B component (sheath) N610 N610 N610 Relative viscosity of crystalline polyamide A component (core) 3.3 3.6 3.6 Relative viscosity of crystalline polyamide B component (sheath) 2.7 2.7 2.7 Original silk characteristics Total fineness dtex 62 62 62 strength cN/dtex 3.5 3.4 3.5 Stretch % 66 65 66 Stretching elongation % 49 53 67 Water absorption % 3.8 3.8 3.6 Thermal shrinkage stress cN/dtex 0.16 0.21 0.25 Rigid amorphous amount % 41 46 53 False twisted yarn Stretching elongation % 130 150 200 Fabric performance Stretchability B B A

[Example 4] Use a copolymer of nylon 6 and nylon 66 (N6/N66) with a relative viscosity of 3.6 and a melting point of 200°C as the crystalline polyamide (A), and a nylon 610 (N610) with a relative viscosity of 2.7 and a melting point of 225°C as the Crystalline polyamide (B). The crystalline polyamide (A) is used as the core component, and the crystalline polyamide (B) is used as the sheath component. They are melted separately, and an eccentric core sheath type composite fiber spinning nozzle (12 holes, round holes) is used to combine The composite ratio (mass ratio) of crystalline polyamide (A) and crystalline polyamide (B) is set as crystalline polyamide (A): crystalline polyamide (B) = 5: 5 for melt discharge (Spinning temperature 270°C). The thread spit out from the spinning nozzle is cooled and solidified by the thread cooling device. After the non-aqueous oil is supplied to the oil device, the thread is interlaced by the fluid interlacing nozzle device, and then the draw roll is slightly heated (temperature 50°C) is drawn at 1700m/min, and after being stretched 2.4 times between heated extension rolls (heat setting temperature: 150°C), it is wound into a package at a winding speed of 4000m/min. A polyamide composite fiber yarn with 62dtex12 monofilament, stretch elongation 117%, water absorption 3.6%, heat shrinkage stress 0.29cN/dtex, and rigid amorphous content 55% was obtained. The obtained polyamide composite fiber yarns are used as warp threads to form a fabric. The obtained fabric has better stretchability than that of Example 5. The results are shown in Table 2.

[Example 5] Nylon 6 (N6) with a relative viscosity of 3.3 and a melting point of 222°C was used as the crystalline polyamide (A), and nylon 610 (N610) with a relative viscosity of 2.7 and a melting point of 225°C was used as the crystalline polyamide (B). The crystalline polyamide (A) is used as the core component, and the crystalline polyamide (B) is used as the sheath component. They are melted separately, and an eccentric core sheath type composite fiber spinning nozzle (12 holes, round holes) is used to combine The composite ratio of crystalline polyamide (A) and crystalline polyamide (B) is set as crystalline polyamide (A): crystalline polyamide (B)=5:5 for melt discharge (spinning temperature) 270°C). The thread spit out from the spinning nozzle is cooled and solidified by the thread cooling device. After the non-aqueous oil is supplied to the oil device, the thread is interlaced by the fluid interlacing nozzle device, and then the draw roll is slightly heated (temperature 50°C) is drawn at 1700m/min, and after being stretched 2.4 times between heated extension rolls (heat setting temperature: 150°C), it is wound into a package at a winding speed of 4000m/min. A polyamide composite fiber yarn with 62 dtex12 monofilament, 83% stretch elongation, 3.8% water absorption, 0.20 cN/dtex thermal shrinkage stress, and 46% rigid amorphous content was obtained. The resulting composite fiber thread is used as the warp to form a fabric. The resulting fabric has excellent stretchability. The results are shown in Table 2.

[Example 6] Except that the composite ratio of crystalline polyamide (A) and crystalline polyamide (B) is set to crystalline polyamide (A): crystalline polyamide (B)=4:6, the implementation is carried out according to In the same manner as in Example 5, a polyamide composite fiber yarn with 62 dtex12 monofilament, stretch elongation rate 81%, water absorption rate 3.3%, heat shrinkage stress 0.18 cN/dtex, and rigid amorphous content 45% was obtained. The obtained polyamide composite fiber yarns are used as warp threads to form a fabric. The resulting fabric has excellent stretchability. The results are shown in Table 2.

[Example 7] Except that the composite ratio of crystalline polyamide (A) and crystalline polyamide (B) is set to crystalline polyamide (A): crystalline polyamide (B) = 6:4, the implementation is in accordance with In the same way as in Example 5, a polyamide composite fiber yarn with 62 dtex12 monofilament, stretch elongation 87%, water absorption 4.3%, thermal shrinkage stress 0.23 cN/dtex, and rigid amorphous content 47% was obtained. The obtained polyamide composite fiber yarns are used as warp threads to form a fabric. The resulting fabric has excellent stretchability. The results are shown in Table 2.

[Example 8] In addition to using nylon 6 (N6) with a relative viscosity of 3.6 and a melting point of 222°C as the crystalline polyamide (A), a copolymer of nylon 610 and nylon 510 (N610/N510) with a relative viscosity of 2.7 and a melting point of 225°C is used. Except for the crystalline polyamide (B), the same method as in Example 5 was followed to obtain 62dtex12 monofilament, stretch elongation 103%, water absorption 4.1%, thermal shrinkage stress 0.20cN/dtex, and rigid amorphous content 46% The polyamide composite fiber yarn. The obtained polyamide composite fiber yarns are used as warp threads to form a fabric. The obtained fabric has better stretchability than that of Example 5. The results are shown in Table 2.

[Example 9] Except that a micro-heating drawing roll (50°C) is used for drawing at 2050m/min, and a heating drawing roll (heat setting temperature: 150°C) is used for stretching to 2.0 times, the same method as in Example 5 is used to obtain 62dtex12 Polyamide composite fiber yarn with monofilament, stretch elongation rate 82%, water absorption rate 3.8%, heat shrinkage stress 0.18cN/dtex, and rigid amorphous content of 43%. The obtained polyamide composite fiber yarns are used as warp threads to form a fabric. The resulting fabric has excellent stretchability. The results are shown in Table 2.

[Example 10] Except that the spinning temperature was set to 280°C, the same method as in Example 5 was followed to obtain 62dtex12 monofilament, stretch elongation 82%, water absorption 3.8%, thermal shrinkage stress 0.18cN/dtex, and rigid amorphous content 43% The polyamide composite fiber yarn. The obtained polyamide composite fiber yarns are used as warp threads to form a fabric. The resulting fabric has excellent stretchability. The results are shown in Table 2.

[Example 11] Except that the spinning temperature was set to 260°C, the same method as in Example 5 was followed to obtain 62dtex12 monofilament, stretch elongation 95%, water absorption 3.8%, thermal shrinkage stress 0.22cN/dtex, and rigid amorphous content 49% The polyamide composite fiber yarn. The obtained polyamide composite fiber yarns are used as warp threads to form a fabric. The resulting fabric has excellent stretchability. The results are shown in Table 2.

[Comparative Example 1] Except that nylon 6 (N6) with a relative viscosity of 2.7 and a melting point of 222° C. was used as the crystalline polyamide (A), the same method as in Example 5 was followed to obtain a polyamide composite yarn with 62 dtex 12 monofilament. The composite yarn of Comparative Example 1 with almost no difference in relative viscosity is crimped with a small shrinkage difference after heat treatment and a stretch elongation as low as 13%, a heat shrinkage stress of 0.13 cN/dtex, and a rigid amorphous content as low as 39% Value. Using the obtained polyamide composite fiber thread as the warp to form a woven fabric, the stretchability of the resulting woven fabric deteriorates. The results are shown in Table 2.

[Comparative Example 2] Except that the composite ratio of crystalline polyamide (A) and crystalline polyamide (B) is set to crystalline polyamide (A): crystalline polyamide (B) = 7: 3, the implementation is carried out in accordance with In the same way as in Example 5, a polyamide composite yarn of 62dtex12 monofilament was obtained. The polyamide composite yarn of Comparative Example 2 in which the ratio of polyamide (A) with a higher water absorption rate is increased, has a water absorption rate as high as 5.8%. Using the obtained polyamide composite fiber yarn as the warp, a woven fabric was formed in the same manner as in Example 5. However, since wrinkles remained, the tension was increased in the warp direction to the extent that no wrinkles were left and processed. As a result, stretchability was obtained. Deteriorated fabric. The results are shown in Table 2.

[Comparative Example 3] In addition to using nylon 6 (N6) with a relative viscosity of 3.3 and a melting point of 222°C as the crystalline polyamide (A), and using nylon 6 (N6) with a relative viscosity of 2.7 and a melting point of 225°C as the crystalline polyamide (B) Otherwise, according to the same method as in Example 5, a polyamide composite fiber strand of 62 dtex12 monofilament was obtained. The polyamide composite fiber yarn of Comparative Example 3 made by using the same kind of polyamide with higher water absorption rate has a water absorption rate as high as 6.2%. Using the obtained polyamide composite fiber yarn as the warp, a woven fabric was formed in the same manner as in Example 5. However, since wrinkles remained, the tension was increased in the warp direction to the extent that no wrinkles were left and processed. As a result, stretchability was obtained. Deteriorated fabric. The results are shown in Table 2.

[Comparative Example 4] Except that the spinning temperature was set to 300°C, the same method as in Example 5 was followed to obtain 62dtex12 monofilament, stretch elongation 53%, water absorption 3.8%, thermal shrinkage stress 0.13cN/dtex, and rigid amorphous content 36% The polyamide composite fiber yarn. The obtained polyamide composite fiber yarns are used as warp threads to form a fabric. The resulting fabric has deteriorated stretchability. The results are shown in Table 2.

[Table 2] Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Example 11 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Crystalline polyamide A component (core) N6/N66 N6 N6 N6 N6 N6 N6 N6 N6 N6 N6 N6 Crystalline polyamide B component (sheath) N610 N610 N610 N610 N610/N510 N610 N610 N610 N610 N610 N6 N610 Relative viscosity of crystalline polyamide A component (core) 3.6 3.3 3.3 3.3 3.6 3.3 3.3 3.3 2.7 3.3 3.3 3.3 Relative viscosity of crystalline polyamide B component (sheath) 2.7 2.7 2.7 2.7 2.7 2.7 2.7 2.7 2.7 2.7 2.7 2.7 Compound ratio (A:B) 5:5 5:5 4:6 6:4 5:5 5:5 5:5 5:5 5:5 7:3 5:5 5:5 Spinning temperature °C 270 270 270 270 270 270 280 260 270 270 270 300 Silk making conditions Take-up roller temperature °C 50 50 50 50 50 50 50 50 50 50 50 50 Pulling roller speed m/min 1700 1700 1700 1700 1700 2050 1700 1700 1700 1700 1700 1700 Extension roll temperature °C 150 150 150 150 150 150 150 150 150 150 150 150 Stretching ratio Times 2.4 2.4 2.4 2.4 2.4 2.0 2.4 2.4 2.4 2.4 2.0 2.4 Original silk characteristics Total fineness dtex 62 62 62 62 62 62 62 62 62 62 62 62 strength cN/dtex 4.6 4.5 4.5 4.5 4.6 4.3 4.6 4.6 4.6 4.6 4.6 4.6 Stretch % 45 46 45 45 46 45 47 46 45 44 46 26 Stretching elongation % 117 83 81 87 103 82 82 95 13 93 79 53 Water absorption % 3.6 3.8 3.3 4.3 4.1 3.8 3.8 3.8 3.8 5.8 6.2 3.8 Thermal shrinkage stress cN/dtex 0.29 0.20 0.18 0.23 0.20 0.18 0.18 0.22 0.13 0.26 0.19 0.13 Rigid amorphous amount % 55 46 45 47 46 43 43 49 39 52 45 36 Fabric performance Stretchability A B B B A B B B C C C C

The present invention has been described in detail using specific aspects above, but those skilled in the art of the present invention will know that various changes and modifications can be made without departing from the intent and scope of the present invention. In addition, this case is based on a Japanese patent application (Japanese Patent Application No. 2019-141540) filed on July 31, 2019, and the entire content is quoted here.

1: Core component (crystalline polyamide (A)) 2: sheath component (crystalline polyamide (B)) 10A~10D: Polyamide eccentric core sheath composite fiber

Fig. 1 is a schematic cross-sectional view illustrating the cross-section of the eccentric core-sheath type polyamide composite fiber of the present invention. 2(A) to 2(C) are schematic cross-sectional views illustrating the cross-sections of other eccentric core-sheath polyamide composite fibers of the present invention.

1: Core component (crystalline polyamide (A))

2: sheath component (crystalline polyamide (B))

10A: Polyamide eccentric core sheath composite fiber

Claims (7)

A polyamide composite fiber, which is an eccentric core sheath type polyamide composite fiber composed of two different crystalline polyamide (A) and crystalline polyamide (B). The polyamide composite fiber has a water absorption rate of 5.0% or less after being allowed to stand for 72 hours in an environment with a temperature of 30° C. and a relative humidity of 90 RH%, and the heat shrinkage stress is 0.15 cN/dtex or more. Such as the polyamide composite fiber of claim 1, wherein the rigid amorphous content of the polyamide composite fiber is 40-60%, and the stretch elongation is more than 30%. The polyamide composite fiber of claim 1 or 2, wherein the crystalline polyamide (A) is nylon 6 or its copolymer. The polyamide composite fiber according to any one of claims 1 to 3, wherein the crystalline polyamide (B) is nylon 610 or its copolymer. The polyamide composite fiber according to any one of claims 1 to 4, wherein the crystalline polyamide (A) is a core component, and the crystalline polyamide (B) is a sheath component. A processed yarn is composed of the polyamide composite fiber according to any one of claims 1 to 5. Such as the processed yarn of claim 6, its stretch elongation is more than 100%.

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