Polyamide bicomponent cross-section fiber

Abstract

The present invention relates to a polyamide bicomponent cross-section fiber comprising two types of polyamide satisfying items A-D. A: The fiber has a cross-section with a bicomponent form of a side-by-side type or an eccentric sheath / core type. B: The 15% stress is 2.0-3.5 cN / Dtex. C: The elongation is 20-40%. D: The high-load stretch elongation rate E2 measured as below is 7.0% or more. A heat treatment load of "total fineness × 5.4 (mg / dtex) ×20 × 2" is applied to a looped hank of the fiber, the hank is treated in hot water at a temperature of 99±1°C for 30 minutes, the heat treatment load is then removed, and the hank is dried in an environment at a temperature of 25°C and a humidity of 60% with no load. An initial load of "total fineness × 5.4 (mg / dtex) × 20 × 2" is applied to the dried hank, the length (La) after 90 seconds is measured, the initial load is removed, a constant load of "90 (mg·dtex) × 20 × 2" is then applied, and the length (Lb) after 30 seconds is measured. The value calculated as "(Lb - La) / La × 100 (%)" is defined as the high-load stretch elongation rate E2.

Description

Polyamide composite cross-section fiber

[0001] The present invention relates to a polyamide composite cross-section fiber having both dyeing fastness and crimpability.

[0002] Polyamide fibers typified by polycaproamide and polyhexamethylene adipamide are widely used not only in clothing applications but also in interior, vehicle interior, industrial applications, etc. because of their excellent mechanical properties and dimensional stability.

[0003] False twist textured yarns with crimpability imparted to polyamide fibers are suitably used for stretchable woven and knitted fabric applications. In polyamide composite cross-section fibers in which two types of polyamides with different compositions are laminated side by side or composite in an eccentric core-sheath type in the fiber cross-section, crimpability can be imparted to the polyamide fiber, and stretchable woven and knitted fabrics have been proposed.

[0004] For example, polyamide composite cross-section fibers (Patent Document 1) in which two types of crystalline polyamides with different compositions are combined in an eccentric core-sheath type and the water absorption rate and thermal shrinkage stress are defined, or polyamide composite cross-section fibers (Patent Document 2) in which two types of polyamides with different viscosities are combined in a side-by-side type or an eccentric core-sheath type and the CF value is defined have been proposed.

[0005] International Publication No. 2021 / 020354 Japanese Patent Application Laid-Open No. 2018-3190

[0006] However, the polyamide composite cross-section fibers in which two different types of polyamides described in Patent Document 1 and Patent Document 2 are combined have problems such as inferior dyeing fastness although they exhibit crimp performance. When polyamides with different compositions and melt viscosities are combined to form a composite cross-section fiber, an orientation difference occurs between the components, and in the components with suppressed orientation, the dye is likely to come off, which has contributed to a significant reduction in dyeing fastness.

[0007] An object of the present invention is to provide a fabric having both dyeing fastness and crimpability, which has been difficult in the prior art, by appropriately controlling the orientation characteristics of the fiber.

[0008] The present invention employs the following configuration to achieve the above objectives: (1) A polyamide composite cross-section fiber consisting of two types of polyamide satisfying items A to D below: A. The composite form of the fiber cross-section is side-by-side or eccentric core-sheath type. B. The 15% stress is 2.0 to 3.5 cN / dtex. C. The elongation is 20 to 40%. D. The high load elongation ratio E2 shown below is 7.0% or more. A heat treatment load of total fineness × 5.4 (mg / dtex) × 20 × 2 is applied to a loop-shaped skein, treated in hot water at a temperature of 99 ± 1°C for 30 minutes, then the heat treatment load is removed, and the fiber is dried in an environment with a temperature of 25°C, humidity of 60%, and no load. An initial load of total fineness × 5.4 (mg / dtex) × 20 × 2 is applied to a dry skein, and the length (La) after 90 seconds is measured. The initial load is removed, and then a constant load of 90 (mg / dtex) × 20 × 2 is applied, and the length (Lb) after 30 seconds is measured. (Lb - La) / La × 100 (%) is defined as the high-load elongation ratio E2. (2) The polyamide composite cross section fiber described in (1) above, wherein each of the two types of polyamide is composed of 95 mol% or more of one type of homopolyamide. (3) A polyamide composite cross section fiber for false twist processing consisting of two types of polyamide that satisfy the following terms E to H. E. The composite form of the fiber cross section is side-by-side type or eccentric core sheath type F. 15% stress is 1.5 to 3.0 cN / dtex G. Elongation is greater than 40% and less than or equal to 80% H. The stretch and elongation ratio E1 shown below is 5.0% or more. A heat treatment load of total fineness × 1.8 (mg / dtex) × 20 × 2 is applied to a loop-shaped hank, and the hank is treated in warm water at a temperature of 99 ± 1°C for 30 minutes. After removing the heat treatment load, the hank is dried in an environment of 25°C, 60% humidity, and no load. An initial load of total fineness × 1.8 (mg / dtex) × 20 × 2 is applied to the dried hank, and the length (L1) is measured after 90 seconds. The initial load is removed, and then a constant load of 90 (mg・dtex) × 20 × 2 is applied, and the length (L2) is measured after 30 seconds. The stretch and elongation ratio E1 is (L2 - L1) / L1 × 100 (%). (4) A woven or knitted fabric made of the polyamide composite cross section fiber described in (1) or (2) above, or the polyamide composite cross section fiber for false twist processing described in (3) above.

[0009] According to the present invention, by appropriately controlling the orientation characteristics of the fibers, it is possible to provide polyamide composite cross-section fibers suitable for woven fabrics that combine excellent colorfastness and crimpability that provides excellent soft stretch when made into fabric.

[0010] Figure 1 shows an example of the composite form of the polyamide composite cross-section fiber of the present invention, with (A) to (C) in Figure 1 being schematic diagrams of a side-by-side type. Figure 2 shows an example of the composite form of the polyamide composite cross-section fiber of the present invention, and is a schematic diagram of an eccentric core sheath type.

[0011] The polyamide composite cross-section fibers of the present invention will be explained in detail. The polyamide composite cross-section fibers of the present invention consist of two types of polyamides. From the viewpoint of crimping characteristics and colorfastness, both types are polyamides, and polymer selection is important due to the ease of promoting polymer orientation and the ease with which orientation differences are expressed when a composite cross-section is formed.

[0012] The polyamides of the present invention are polymers in which so-called hydrocarbons are linked to the main chain via amide bonds. Examples include polycaproamide, polyundecaneamide, polydodecaneamide, polytetramethylene adipamide, polypentamethylene adipamide, polypentamethylene sevacamide, polyhexamethylene adipamide, polyhexamethylene sevacamide, polyhexamethylene dodecaneamide, polyhexamethylene tridecaneamide, and copolymers mainly composed of these. However, from the viewpoint of colorfastness, it is preferable that 95 mol% or more of the polyamide is composed of one type of homopolyamide, which is prone to orientation.

[0013] The two types of polyamides mentioned above are not limited as long as they can impart an orientation difference and promote the orientation of the two polymers. They may have the same composition or different compositions, but in order to obtain the desired crimpability, it is preferable to use polyamides with different compositions. For example, a combination of a polyamide composed of aminocaproic acid units (such as polycaproamide) and a polyamide composed of dicarboxylic acid and diamine units (such as polyhexamethylene adipamide) can be used.

[0014] The composite form of the fiber cross-section of the present invention is either a side-by-side type or an eccentric core-sheath type, from the viewpoint of obtaining the desired crimpability. The side-by-side type and the eccentric core-sheath type refer to the composite forms shown in Figures 1 and 2. In the case of the side-by-side type, the composite interface (bonding surface) may be a straight line as shown in Figure 1(A), or a curved shape as shown in Figures 1(B) and (C). Furthermore, the composite ratio is preferably in the range of 4:1 to 1:4 in terms of the area ratio of the two types of polyamide components.

[0015] The cross-sectional shape of the polyamide composite fiber of the present invention can be appropriately selected as long as the composite form is side-by-side or eccentric core-sheath type, without impairing the effects of the present invention. Examples include circular, elliptical, trilobed, quadruplebed, cross-shaped, hollow, and flattened cross-sections, but a circular shape is preferred from the viewpoint of melt spinnability and ease of spinning.

[0016] In the polyamide composite cross-sectional fibers of the present invention, appropriate control of orientation characteristics is extremely important in order to achieve both crimping characteristics and colorfastness. If this control is not properly performed, even if the crimping performance is good, the colorfastness will be poor.

[0017] The orientation characteristics of composite cross-section fibers change depending on the melt viscosity, extension viscosity, stress applied during spinning, stress applied during stretching, crystallization transition due to heating, and orientation relaxation of the polymer. In the conventional technology described in Patent Documents 1 and 2, crimp characteristics are improved by increasing the orientation difference between polymers and increasing the shrinkage rate and shrinkage stress of the high-shrinkage side polymer. However, on the other hand, the orientation of the low-shrinkage side polymer is suppressed, resulting in a large amount of loose amorphous regions in the fiber structure, which makes dye shedding more likely during dyeing and leads to poor colorfastness. In addition, the stress at 15% elongation of the fiber (also called 15% elongation stress or 15% stress) decreases, making the crimp more prone to sagging, reducing the stretch and elongation rate, and also impairing the firmness of the fabric.

[0018] The 15% tensile stress of the polyamide composite cross-section fiber of the present invention is 2.0 to 3.5 cN / dtex. If the 15% tensile stress is less than 2.0 cN / dtex, the orientation of the low-viscosity polymer is loose and the colorfastness is poor, and if it exceeds 3.5 cN / dtex, the orientation of the low-viscosity polymer is promoted and the crimpability is poor. By setting the 15% tensile stress to 2.0 to 3.5 cN / dtex, good crimpability and colorfastness (resistance to staining due to discoloration, fading, and color bleeding) can be obtained, and it is preferably 2.4 to 3.1 cN / dtex.

[0019] The elongation of the polyamide composite cross-sectional fibers of the present invention is 20-40%, and by keeping it within this range, the passability of the fibers during knitting and weaving when making fabrics is improved, and furthermore, practical durability is excellent.

[0020] The polyamide composite cross-section fibers of the present invention have a high-load stretch elongation ratio E2 of 7.0% or higher, measured under high load during heat treatment. This parameter indicates that the crimping performance of the fibers is not impaired even when woven into fabric. When manufacturing fabrics and textile products, plain weave fabrics and high-density weave fabrics have a large restraining force on the fibers, and high tension is applied during washing and dyeing, such as in open soapers. In order to maintain high crimping performance even after going through such processes, it is necessary that the fibers have high crimping performance even under heat treatment with a high load, and the high-load stretch elongation ratio E2 measured under high load during heat treatment is 7.0% or higher, preferably 10.0% or higher. The upper limit of the high-load stretch elongation ratio E2 is preferably 70% or less. By setting the high-load stretch elongation ratio E2 to 70% or less, shrinkage can be suppressed and wrinkle formation in the fabric can be prevented.

[0021] The high-load elongation ratio E2 can be measured and calculated as follows. More specifically, it can be measured and calculated by the method described in the examples. A heat treatment load of total fineness × 5.4 (mg / dtex) × 20 × 2 is applied to a loop-shaped sack, and it is treated in hot water at a temperature of 99±1°C for 30 minutes. After removing the heat treatment load, it is dried in an environment of 25°C, 60% humidity, and no load. An initial load of total fineness × 5.4 (mg / dtex) × 20 × 2 is applied to the dried sack, and the length (La) after 90 seconds is measured. The initial load is removed, and then a constant load of 90 (mg・dtex) × 20 × 2 is applied, and the length (Lb) after 30 seconds is measured. (Lb - La) / La × 100 (%) is taken as the high-load elongation ratio E2.

[0022] The single filament fineness of the polyamide composite cross-section fiber of the present invention is not limited as long as it does not impair the effects of the present invention. A single filament fineness of 0.8 to 6.0 dtex is suitable for innerwear, outerwear, etc. Furthermore, the total fineness of the polyamide composite cross-section fiber is preferably 4.0 to 200.0 dtex, considering clothing applications.

[0023] The polyamide composite cross-sectional fibers of the present invention may contain various additives, as long as they do not impair the effects of the present invention. Examples of such additives include pigments such as titanium dioxide and carbon black, lightfasteners such as manganese compounds, antioxidants such as hindered phenols and phosphorus compounds, heat-resistant agents, flame retardants, conductivity imparters, fibrous reinforcing agents, viscosity modifiers, and crystallization accelerators.

[0024] Next, the method for producing the polyamide composite cross-section fibers of the present invention will be described. The polyamide composite cross-section fibers for false-twist processing, described later, are obtained by the following false-twist processing. Preferably, the false-twist processing is performed using a stretch friction false-twist processing apparatus.

[0025] For example, the polyamide composite cross-section fibers for false twisting, as described later, supplied to the stretch friction false twisting machine are sent to the supply rollers via desired yarn guides and fluid processing equipment. They are then guided to the stretch rollers through a heated false twist heater, cooling plates, and a twisting body that performs stretch friction false twisting, and are wound up as false twisted yarn.

[0026] Stretch friction false twisting may be performed after stretching with a hot pin or hot plate before the supply roller of the stretch friction false twisting apparatus, or it may be performed while stretching is occurring between the supply roller and the stretch roller.

[0027] Examples of twisting bodies include pin type, friction type, and belt nip type, but are not limited to these. When you want to increase the crimp, it is preferable to use the pin type, and when you want to increase the processing speed and reduce production costs, it is preferable to use the friction type or belt nip type.

[0028] Heating methods include high-temperature contact heaters and high-temperature non-contact heaters. By thoroughly heating the yarn with a high-temperature contact heater, the molecules within the fiber are rearranged and the twist is fixed, resulting in high crimp performance. The processing temperature (for example, the heater setting temperature in the case of a contact heating plate) is preferably -100°C to -10°C of the melting point of each polymer. If the processing temperature (for example, the heater setting temperature) is above -100°C of the melting point of each polymer, the fiber can be sufficiently plasticized, making it easier to impart twist, and the crimping properties of the fiber can be expressed, resulting in fabrics and textile products with excellent soft stretchability. In addition, the degree of crystallinity of the low-viscosity polyamide is also increased, so the fiber structure is stabilized, and the amorphous parts with a loose structure that are prone to dye bleeding are reduced, resulting in excellent colorfastness. Furthermore, stable high-order processing (false twisting, weaving, knitting, dyeing, etc.) is possible even after long-term storage. When the processing temperature (e.g., heater setting temperature) is below -10°C of the melting point of each polymer, the crystallinity of the high-viscosity polyamide can be suppressed, resulting in greater shrinkage. This makes the fiber easier to crimp, and prevents the overall crystallinity from becoming too high, thus achieving high dyeability. Furthermore, fusion during false twisting is less likely to occur, improving processing passability and product quality.

[0029] Cooling methods include using a cooling plate, air cooling, and water cooling, and are not limited to these methods. However, considering efficiency and damage to the thread, using a cooling plate is preferable.

[0030] The ratio of the twisting tension T1 to the untwisting tension T2 (T2 / T1) is preferably 0.7 to 1.0. When T2 / T1 is 1.0 or less, i.e., when the untwisting tension T2 is small, the generation of fluff, i.e., single-fiber breakage, can be suppressed, so there is less yarn breakage after passing through the twisting body, stable stretch friction false twisting is possible, and the resulting false-twisted yarn is of excellent quality. By setting T2 / T1 to 0.7 or more, untwisting defects can be suppressed, and high crimp can be obtained.

[0031] It is preferable that the ratio of the surface speed D of the twisting body to the surface speed Y of the stretching roller (D / Y ratio) is 1.0 to 2.0. By setting the D / Y ratio to 1.0 or higher, a good balance is achieved between the twisting tension T1 and the untwisting tension T2, enabling stretch friction false twisting without fuzzing or yarn breakage. Furthermore, by setting the D / Y ratio to 2.0 or lower, surface wear of the twisting body is suppressed, the quality in the longitudinal direction of the yarn remains stable even during continuous operation for tens of hours, and stretch friction false twisting without fuzzing or yarn breakage is achieved.

[0032] The [Polyamide Composite Cross Section Fiber for False Twist Processing] will be described in detail. The polyamide composite cross section fiber for false twist processing of the present invention consists of two types of polyamide. From the viewpoint of high-order passability and quality such as fluff during false twist processing, it is important to select a polymer that takes into account the ease of promoting polymer orientation and the ease with which orientation differences are expressed when a composite cross section is formed.

[0033] The polyamides of the present invention are polymers in which so-called hydrocarbons are linked to the main chain via amide bonds. Examples include polycaproamide, polyundecaneamide, polydodecaneamide, polytetramethylene adipamide, polypentamethylene adipamide, polypentamethylene sevacamide, polyhexamethylene adipamide, polyhexamethylene sevacamide, polyhexamethylene dodecaneamide, polyhexamethylene tridecaneamide, and copolymers mainly composed of these. However, from the viewpoint of avoiding fusion during false twisting, it is preferable that 95 mol% or more of the polyamide is composed of one type of homopolyamide, which promotes orientation.

[0034] The two types of polyamides mentioned above are not limited as long as they can impart an orientation difference and promote the orientation of the two polymers. They may have the same composition or different compositions, but it is preferable to use polyamides with different compositions in order to create a shrinkage difference due to the difference in heat setting during false twisting. For example, a combination of a polyamide composed of aminocaproic acid units (such as polycaproamide) and a polyamide composed of dicarboxylic acid and diamine units (such as polyhexamethylene adipamide) is used.

[0035] The composite form of the fiber cross-section of the present invention is either a side-by-side type or an eccentric core-sheath type, from the viewpoint of ease of processing in false twisting. The side-by-side type and the eccentric core-sheath type refer to the composite forms shown in Figures 1 and 2. In the case of the side-by-side type, the composite interface (bonding surface) may be a straight line as shown in Figure 1(A), or a curved shape as shown in Figures 1(B) and (C). Furthermore, the composite ratio is preferably in the range of 4:1 to 1:4 in terms of area ratio of the component ratio of the two types of polyamide.

[0036] In the polyamide composite cross-section fibers for false-twist processing of the present invention, appropriate control of orientation characteristics is extremely important in order to suppress the generation of fluff during processing. If this control is not properly performed, the false-twisted yarn obtained from the polyamide composite cross-section fibers for false-twist processing will have good crimping performance but poor colorfastness. The orientation characteristics of composite cross-section fibers change depending on the melt viscosity, extension viscosity of the polymer, the stress applied during spinning, the stress applied during stretching, crystallization transition due to heating, and orientation relaxation. In the conventional fibers described in Patent Documents 1 and 2, the orientation difference between polymers is large, and the shrinkage rate and shrinkage stress of the high-viscosity polymer are large, so the orientation of the low-viscosity polymer is suppressed, the fiber structure has many loose amorphous parts, and fusion is likely to occur during false-twist processing. In addition, the stress when the fiber is stretched by 15% decreases, the yarn deformation becomes easy, it is more likely to get caught at the contact point in the yarn path, and yarn breakage is likely to occur.

[0037] By setting the 15% tensile stress of the polyamide composite cross-section fiber for false-twist processing of the present invention to 1.5 to 3.0 cN / dtex, the 15% tensile stress of the false-twisted yarn obtained in the next process can be controlled to 2.0 to 3.5 cN / dtex. Preferably, the 15% tensile stress of the polyamide composite cross-section fiber for false-twist processing is 1.7 to 2.7 cN / dtex.

[0038] The polyamide composite cross-section fiber for false-twist processing of the present invention has an elongation of more than 40% and less than or equal to 80%, which provides stable stretchability during false-twist processing and suppresses the generation of fluff and uneven dyeing in the longitudinal direction of the false-twisted yarn.

[0039] The elongation rate E1 of the polyamide composite cross-section fiber for false twisting according to the present invention is 5.0% or higher. This makes it possible to control the high-load elongation rate E2 of the false-twisted yarn obtained in the next process to 7.0% or higher. Furthermore, considering the processing stability of the post-processing steps, an elongation rate E1 of 100% or less is preferable. Processing stability refers to improvements in yarn breakage during the processing steps, defects in the winding package foam, and poor unwinding from the package.

[0040] The elongation rate E1 can be measured and calculated as follows. More specifically, it can be measured and calculated by the method described in the example. A heat treatment load of total fineness × 1.8 (mg / dtex) × 20 × 2 is applied to a loop-shaped skein, and it is treated in hot water at a temperature of 99 ± 1°C for 30 minutes. After removing the heat treatment load, it is dried in an environment of 25°C, 60% humidity, and no load. An initial load of total fineness × 1.8 (mg / dtex) × 20 × 2 is applied to the dried skein, and the length (L1) after 90 seconds is measured. The initial load is removed, and then a constant load of 90 (mg / dtex) × 20 × 2 is applied, and the length (L2) after 30 seconds is measured. The elongation rate E1 is (L2 - L1) / L1 × 100 (%).

[0041] The polyamide composite cross-section fiber for false-twist processing of the present invention can exhibit apparent crimp when false-twisted, and the crimping properties are dramatically improved by the different three-dimensional crimping of latent and apparent crimping due to the composite cross-section. Furthermore, because it is slightly stretched by false-twist processing, orientation is promoted, and thus the colorfastness is also improved.

[0042] Next, the manufacturing method of the polyamide composite cross-section fiber for false twist processing of the present invention will be explained. The two types of polyamides used in the polyamide composite cross-section fiber for false twist processing of the present invention may have the same composition or different compositions, but in order to obtain the desired crimpability, it is preferable that they are made of polyamides with different compositions. For example, polycaproamide and polyhexamethylene adipamide are one of the preferable combinations. When the composite cross-section fiber is constituted by polyamides having the same composition, a difference in the degree of polymerization may be provided between the two. Also, for example, titanium oxide may be contained only in one of them to cause a composition difference.

[0043] Regarding the said difference in the degree of polymerization, the melt viscosity difference between the two types of polyamides is preferably 200 poise or more, more preferably 300 poise or more, particularly preferably 400 poise or more, and the melt viscosity on the high viscosity side is preferably 800 poise or more, and the melt viscosity on the low viscosity side is preferably 400 poise or more.

[0044] The melting section of the manufacturing process will be explained. When melting the two types of polyamides, the pressure melter method or the extruder method can be mentioned, but it is not particularly limited. The melting temperature may be appropriately determined in consideration of the melting point of the polyamide resin, but as a preferable melting temperature, they are melted separately at a temperature 20°C to 60°C higher than the melting point of the polyamide resin.

[0045] The spinning temperature is the same as the melting temperature and may be appropriately determined in consideration of the melting point of the polyamide resin. Here, the spinning temperature refers to the so-called heat preservation temperature (spin block temperature) that keeps the polymer pipe, metering pump, spinneret, etc. warm.

[0046] It is important to appropriately control the moisture supply, spinning tension, and draw ratio during extrusion from the spinneret. From the perspective of controlling these factors, the direct spinning and drawing method is superior, and the manufacturing method using the direct spinning and drawing method is illustrated below. Two types of polyamide, which are melted separately, are measured and supplied to a composite spinneret that forms either a side-by-side type or an eccentric core-sheath type. Here, the two types of polyamide merge and are extruded from the spinneret's extrusion hole as a side-by-side type or eccentric core-sheath type polyamide composite cross-section fiber. The extruded yarn is moistened using a water vapor supply device, and after the gaseous low polymer components coming out of the yarn are removed by suction (MO suction), the yarn is cooled to room temperature by blowing cooling air onto it using a yarn cooling device such as a chimney. Next, the fibers are lubricated and bundled using a lubrication device, entangled in a fluid treatment device, lubricated again and bundled using a lubrication device if necessary, taken up by a take-up roller, and passed through a stretching roller, where they are stretched appropriately according to the ratio of the peripheral speeds of the take-up roller and the stretching roller. After stretching, it is preferable to heat-set the fibers, whether they are stretched yarn or semi-stretched yarn, and thereafter they are wound up by a winding device.

[0047] In the production of polyamide composite cross-sectional fibers of the present invention, it is important to control the fiber structure formation from extrusion to winding in order to control the elongation rate under a 0.18 mg / dtex load (E1), the elongation rate under a 5.4 mg / dtex load (E2), and the 15% elongation stress, which are parameter indicators of crimp characteristics (crimp fastness) and orientation characteristics (dye fastness), within a desired range. This fiber structure formation can be controlled by spinning tension and drawing tension, and can also be controlled by promoting orientation crystallization by adding moisture (water-containing oil supply, water vapor application, etc.), drawing ratio, etc.

[0048] It is preferable that the steam flow rate in the steam supply device is in the range of 30 to 200 L / min. By setting the flow rate within this range, moisture can be imparted to the yarn, the plasticization of polyamide can proceed, and orientation can be promoted after the polymer thinning point. When the steam flow rate is less than 30 L / min, particularly, the orientation of the low shrinkage side polymer is suppressed, and the dyeing fastness deteriorates. The steam flow rate is more preferably 40 L / min or more, and even more preferably 50 L / min or more. When the steam flow rate exceeds 200 L / min, turbulence is likely to occur on the die surface, yarn breakage is likely to occur, and productivity deteriorates. The steam flow rate is more preferably 190 L / min or less, 180 L / min or less, 170 L / min or less, and 150 L / min or less in stages.

[0049] The spinning tension is 0.15 to 0.70 cN / dtex, preferably 0.20 to 0.65 cN / dtex. Here, the "spinning tension" refers to the tension applied to the yarn after the convergence in cooling and oiling is completed. By setting the spinning tension within this range, the orientation characteristics of the two types of polyamides in the present invention can be appropriately controlled, so that a polyamide composite cross-section fiber excellent in both crimp performance and dyeing fastness can be obtained, and a fabric or fiber product rich in soft stretchability can be obtained.

[0050] When the spinning tension is less than 0.15 cN / dtex, since there is no orientation difference between the two types of polyamides, the crimpability of the fiber does not appear, and a fabric or fiber product rich in soft stretchability cannot be obtained. When the spinning tension exceeds 0.70 cN / dtex, the orientation of the polyamide on the low orientation side is suppressed, and unless stretching or the like promotes orientation, even if the crimp performance is excellent, only a fabric or fiber product inferior in dyeing fastness can be obtained.

[0051] The drawing tension is 0.20 to 0.70 cN / dtex, preferably 0.25 to 0.65 cN / dtex. Here, the "drawing tension" refers to the tension between the drawing roller and the take-up roller. By setting the drawing tension within this range, the orientation characteristics of the two types of polyamides in the present invention can be appropriately controlled, so that a polyamide composite cross-section fiber excellent in both crimp performance and dyeing fastness can be obtained, and a fabric or fiber product rich in soft stretchability can be obtained.

[0052] If the tensile strength is less than 0.20 cN / dtex, orientation does not progress and the orientation becomes small, resulting in a decrease in the colorfastness of the fiber. In addition, the elongation strength of the fiber decreases, and the practical durability of the fabric or textile product is greatly reduced. If the tensile strength exceeds 0.70 cN / dtex, the orientation of the entire polyamide composite cross-section fiber increases, so no shrinkage difference occurs, and only fabrics or textile products with inferior crimping performance can be obtained.

[0053] The heat setting temperature is preferably in the range of 100 to 200°C, and more preferably in the range of 130 to 190°C. When the heat setting temperature is 100°C or higher, the orientation obtained by appropriately controlling the spinning draft and draw ratio is not relaxed, and as a result, the orientation difference between the two types of polyamide can be maintained, the crimpability of the fiber is expressed, and a fabric or textile product with excellent soft stretchability can be obtained. In addition, the degree of crystallinity of the low-oriented polyamide is also increased, so the fiber structure is stabilized, and the amorphous parts with a loose structure that are prone to dye bleeding are reduced, resulting in excellent colorfastness. Furthermore, stable advanced processing (false twisting, weaving, knitting, dyeing, etc.) is possible even after long-term storage. When the heat setting temperature is 200°C or lower, the degree of crystallinity of the high-shrinkage side does not become too high, and shrinkage is increased, making it easier for the crimpability of the fiber to be expressed, and the overall degree of crystallinity does not become too high, resulting in high dyeability.

[0054] It is highly preferable to heat-set the polyamide composite cross-section fibers for false-twist processing of the present invention. Normally, false-twist processing fibers with an elongation exceeding 40% are not heat-set. This is because heat-setting promotes crystallization of the fibers, reducing the amorphous strain portion that is subject to twist deformation, resulting in low crimp performance of the resulting false-twist yarn. However, in the case of the two types of polyamides in the present invention, controlling the degree of orientation is more important, and it is highly preferable to heat-set them in order to appropriately control the degree of orientation.

[0055] Regarding the heat setting method, as exemplified by the direct spinning and drawing method, it involves bringing the yarn into contact with a heating element after drawing. Preferably, a method is used in which a heating element is installed inside the drawing roller, and the yarn held (in contact with) the drawing roller is heat-set.

[0056] The winding speed can be set appropriately within a range that allows various parameters such as the 15% stress and elongation ratio of the two types of polyamides in the present invention to be within the desired range and that enables stable manufacturing, but a range of 3000 to 5000 m / min is preferred.

[0057] The polyamide composite cross-section fibers of the present invention and the polyamide composite cross-section fibers for false twisting of the present invention can be woven and knitted according to known methods. Furthermore, the structure of the woven or knitted fabric is not limited. In the case of woven fabrics, the structure may be plain weave, twill weave, satin weave, or variations thereof, or a mixed weave, depending on the intended use. However, to produce a woven fabric with a firm, voluminous feel, a plain weave with many constraint points, or a ripstop weave combining plain weave with a rhinestone or nanako weave is preferred. In the case of knitted fabrics, the structure may be jersey weave, interlock weave, half weave, satin weave, jacquard weave, or variations thereof, or a mixed weave, depending on the intended use. However, a single tricot knit fabric with a half weave is preferred because it is thin, stable, and has excellent elongation.

[0058] The applications of woven or knitted fabrics using the polyamide composite cross-section fibers of the present invention or the false-twist polyamide composite cross-section fibers of the present invention are not limited, but are preferably for clothing, and more preferably for sportswear such as down jackets, windbreakers, golf wear, and rainwear, as well as women's and men's clothing.

[0059] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The methods for measuring characteristic values ​​in the examples are as follows.

[0060] A. Total Fineness, Single Filament Fineness (Total Fineness) A yarn sample was set in a measuring machine with a circumference of 1 m, rotated 250 times to create a loop-shaped skein, dried in a hot air dryer (105 ± 2°C × 60 minutes), and the skein weight was measured using a weighing balance. The total fineness was calculated from the value obtained by multiplying the weight by the official moisture content. The official moisture content was uniformly set at 4.5%. (Single Filament Fineness) The single filament fineness was calculated by dividing the total fineness by the number of filaments.

[0061] B. Elongation E1 The elongation ratio was measured in accordance with JIS L 1013 8.11 Elasticity (Method C) (2010 edition). Using a measuring machine with a tension adjustment device, a 10-turn skein was made with a tension of total fineness × 0.294 (mN / dtex). A heat treatment load of total fineness × 1.8 (mg / dtex) × 20 × 2 was applied to the loop-shaped skein and treated in hot water at a temperature of 99±1°C for 30 minutes. Next, the heat treatment load was removed and the skein was dried in an environment with a temperature of 25°C, humidity of 60%, and no load. An initial load of total fiber thickness × 1.8 (mg / dtex) × 20 × 2 was applied to a dry skein, and the length (L1) after 90 seconds was measured. Next, the initial load was removed, and a constant load of 90 (mg / dtex) × 20 × 2 was applied, and the length (L2) after 30 seconds was measured. The elongation ratio E1 was calculated as (L2 - L1) / L1 × 100 (%).

[0062] C. High-Load Elongation Ratio E2 The high-load elongation ratio E2 was defined as the measured value under a load in which the heat treatment load and initial load were changed to 5.4 (mg / dtex) using the same method as described above for the elongation ratio.

[0063] D. Melt viscosity: Using a Capillograph 1D manufactured by Toyo Seiki Seisakusho Co., Ltd., the measurement conditions were set to L / D = 10, spinning temperature 285°C, and measurement speed mm / min. After introducing the sample into the instrument, it was left to stand for 5 minutes, and the melt viscosity was measured.

[0064] E. 0.25 g of the 98% sulfuric acid relative viscosity sample was dissolved in 100 ml of 98% by weight sulfuric acid to a total volume of 1 g, and the flow time T1 at 25°C was measured using an Ostwald viscometer. Subsequently, the flow time T2 of 98% by weight sulfuric acid alone was measured. The ratio of T1 to T2, i.e., T1 / T2, was defined as the relative viscosity of 98% sulfuric acid.

[0065] F. 15% Stress, Strength, and Elongation Fiber samples were measured according to JIS L1013 (2010) for tensile strength and elongation. The test conditions were a constant-speed tensioning tester, a gripping distance of 50 cm, and a tensile speed of 50 cm / min. If the strength at break was less than the maximum strength, the maximum strength and the elongation at that time were measured. The 15% stress and strength were calculated using the following formulas: 15% stress = Strength at 15% elongation (cN) / Total fineness (dtex) Strength = Strength at break (cN) / Total fineness (dtex) Elongation = Elongation at break (%)

[0066] G. Spinning tension and draw tension: Using a digital tension meter (INTEC, model: IT-100P), the tension was measured before entanglement was introduced in the fluid processing device, and the value obtained by dividing this by the total fineness was defined as the spinning tension (cN / dtex). In addition, the tension was measured between the take-up roller and the draw roller, and the value obtained by dividing this by the total fineness was defined as the draw tension (cN / dtex).

[0067] H. Fabric Stretch In accordance with JIS L 1096 (Method A) (Constant Speed ​​Elongation Method: 2010 Edition), an Instron tensile testing machine was used to measure the elongation rate of a 50 mm wide x 300 mm wide sample stretched in both the warp and weft directions at a gripping distance of 200 mm and a tensile speed of 200 mm / min up to 14.7 N. The measurement results were categorized as follows, with ◎ and ○ indicating pass / fail. ◎: 30.0% or more ○: 20.0% or more and less than 30.0% △: 15.0% or more and less than 20.0% ×: Less than 15.0%

[0068] I. Colorfastness Measured according to JIS L0844 (2011) Section 7.1 Method A, under A-2 conditions. Judgment was made according to the visual method of JIS L0801 (2011) Section 10(a), with grades determined for discoloration and staining. The measurement results were categorized as follows, with ◎ and ○ indicating pass. ◎: Discoloration and staining judged as Grade 4 or higher. ○: Discoloration and staining judged as Grade 3 or Grade 3-4. △: Either discoloration or staining judged as Grade 2-3 or lower.

[0069] Example 1 Polycaproamide (98% sulfuric acid relative viscosity: 3.25, melt viscosity: 1600 poise, tip moisture content: 100 ppm, melting point: 225°C) was used as the core component polyamide (A) and melted at 285°C. Polyhexamethylene adipamide (98% sulfuric acid relative viscosity: 2.60, melt viscosity: 700 poise, tip moisture content: 1200 ppm, melting point: 255°C) was used as the sheath component polyamide (B) and melted at 285°C. Both were melted in a pressure melter and extruded using a composite spinneret for eccentric core and sheath (24 holes x 2 groups, round holes).

[0070] The area ratio of polyamide (A) to polyamide (B) (polyamide A / polyamide B) and the spinning tension are shown in Table 1.

[0071] Furthermore, the discharged yarn was treated with water using a steam application device (steam flow rate 75 L / min), then suctioned with MO, and cooled and solidified to room temperature by blowing cooling air (wind speed 30 m / min, wind temperature 20°C) through a Uniflow chimney. After the cooled and solidified yarn was lubricated with a water-containing oil agent using an oil supply device, entanglement was introduced using a fluid treatment device, and then the water-containing oil agent was lubricated again using the oil supply device.

[0072] For stretching, the stretching tension is as shown in Table 1. For heat setting, a heating element is installed inside the stretching roller and brought into contact with the stretching roller, and the stretching roller surface temperature (heat setting temperature) is as shown in Table 1. After stretching and heat setting, the material is wound up on a winding machine to obtain a multifilament (polyamide composite cross-section fiber for false twisting) consisting of 59dtex24 polyamide eccentric core sheath cross-section fibers.

[0073] The total fineness, single filament fineness, 15% stress, elongation, and stretch ratio were measured for the obtained polyamide eccentric core-sheath cross-section fibers. These results are shown in Table 1. The number of filament breaks when producing one ton of polyamide eccentric core-sheath cross-section fibers was also counted.

[0074] The obtained multifilaments were subjected to simultaneous stretching and false twisting using a friction-type stretching and false twisting apparatus at a processing temperature (contact-type hot plate heater setting temperature) of 200°C, a stretching ratio of 1.18, a D / Y ratio of 1.95, and a T2 / T1 ratio of 0.81 to obtain false-twisted yarn of 50 dtex 24 filaments. The total fineness, high-load stretch elongation rate, 15% stress, and elongation of the obtained false-twisted yarn were measured. These results are shown in Table 1.

[0075] Using the obtained false-twisted yarn, a plain weave fabric was prepared with a warp density of 116 threads / 2.54 cm and a weft density of 84 threads / 2.54 cm. Scouring and dyeing were performed using a liquid flow method, and the dry heat setting of the fabric was adjusted as appropriate. The fabric stretch and colorfastness were measured for the obtained fabric. These results are shown in Table 1. The values ​​listed in the fabric stretch column are the elongation rate (%) measured based on "H. Fabric Stretch" described above.

[0076]

[0077] Examples 2-3 and Comparative Example 1: Melt spinning was performed in the same manner as in Example 1, except for the steam flow rate of the steam application device, to obtain 59dtex24 filament polyamide eccentric core-sheath cross-section fibers. The elongation rate, total fineness, single filament fineness, 15% stress, and elongation of the obtained polyamide eccentric core-sheath cross-section fibers were measured. The number of yarn breaks when producing 1 ton of polyamide eccentric core-sheath cross-section fibers was also counted. These results are shown in Table 1.

[0078] The obtained polyamide eccentric core-sheath cross-section fibers were subjected to the same false-twisting process as in Example 1 to obtain false-twisted yarn with approximately 50 dtex 24 filaments. The total fineness, high-load stretch elongation rate, 15% stress, and elongation of the obtained false-twisted yarn were measured. These results are shown in Table 1.

[0079] The obtained false-twisted yarn was subjected to the same advanced processing as in Example 1 to obtain a fabric. The fabric stretch and colorfastness were measured for the obtained fabric. These results are shown in Table 1.

[0080] Examples 4-5 and Comparative Example 2: Melt spinning was performed in the same manner as in Example 1, except for the spinning tension, to obtain 24-filament polyamide eccentric core-sheath cross-section fibers. The elongation rate, total fineness, single filament fineness, 15% stress, and elongation of the obtained polyamide eccentric core-sheath cross-section fibers were measured. The number of yarn breaks when producing 1 ton of polyamide eccentric core-sheath cross-section fibers was also counted. These results are shown in Table 2.

[0081] The obtained polyamide eccentric core-sheath cross-section fibers were subjected to a stretch ratio adjustment to achieve a density of approximately 50 dtex, and false-twist processing was carried out to obtain false-twisted yarn with approximately 50 dtex and 24 filaments. The total fineness, high-load stretch elongation rate, 15% stress, and elongation of the obtained false-twisted yarn were measured. These results are shown in Table 2.

[0082] The obtained false-twisted yarn was subjected to the same advanced processing as in Example 1 to obtain a fabric. The fabric stretch and colorfastness were measured for the obtained fabric. These results are shown in Table 2.

[0083]

[0084] In Example 6 and Comparative Example 3, melt spinning was performed in the same manner as in Example 4, except for the tensile strength, to obtain 24-filament polyamide eccentric core-sheath cross-section fibers. For the obtained polyamide eccentric core-sheath cross-section fibers, the stretch elongation rate, total fineness, single filament fineness, 15% stress, and elongation were measured. The number of yarn breaks when producing 1 ton of polyamide eccentric core-sheath cross-section fibers was also counted. These results are shown in Table 3.

[0085] The obtained polyamide eccentric core-sheath cross-section fibers were subjected to a stretch ratio adjustment to achieve a density of approximately 50 dtex, and false-twist processing was carried out to obtain false-twisted yarn with approximately 50 dtex and 24 filaments. The total fineness, high-load stretch elongation rate, 15% stress, and elongation of the obtained false-twisted yarn were measured. These results are shown in Table 3.

[0086] The obtained false-twisted yarn was subjected to the same advanced processing as in Example 1 to obtain a fabric. The fabric stretch and colorfastness were measured for the obtained fabric. These results are shown in Table 3.

[0087]

[0088] Examples 7-8: Melt spinning was performed in the same manner as in Example 1, except for the heat setting temperature, to obtain polyamide eccentric core-sheath cross-section fibers of 59dtex24 filament. The elongation rate, total fineness, single filament fineness, 15% stress, and elongation of the obtained polyamide eccentric core-sheath cross-section fibers were measured. The number of yarn breaks when producing 1 ton of polyamide eccentric core-sheath cross-section fibers was also counted. These results are shown in Table 3.

[0089] The obtained polyamide eccentric core-sheath cross-section fibers were subjected to false-twist processing in the same manner as in Example 1 to obtain false-twisted yarn with approximately 50 dtex 24 filaments. The total fineness, high-load stretch elongation rate, 15% stress, and elongation of the obtained false-twisted yarn were measured. These results are shown in Table 3.

[0090] The obtained false-twisted yarn was subjected to the same advanced processing as in Example 1 to obtain a fabric. The fabric stretch and colorfastness were measured for the obtained fabric. These results are shown in Table 3.

[0091] Example 9 was melt-spun in the same manner as in Example 1, except that the core component was polycaproamide (98% sulfuric acid relative viscosity: 2.7, melt viscosity: 1000 poise, tip moisture content: 100 ppm, melting point: 225°C) to obtain 59dtex24 filament polyamide eccentric core-sheath cross-section fibers. The elongation rate, total fineness, single filament fineness, 15% stress, and elongation of the obtained polyamide eccentric core-sheath cross-section fibers were measured. The number of yarn breaks when 1 ton of polyamide eccentric core-sheath cross-section fibers was produced was also counted. These results are shown in Table 4.

[0092] The obtained polyamide eccentric core-sheath cross-section fibers were subjected to false-twist processing in the same manner as in Example 1 to obtain false-twisted yarn with approximately 50 dtex 24 filaments. The total fineness, high-load stretch elongation rate, 15% stress, and elongation of the obtained false-twisted yarn were measured. These results are shown in Table 4.

[0093] The obtained false-twisted yarn was subjected to the same advanced processing as in Example 1 to obtain a fabric. The fabric stretch and colorfastness were measured for the obtained fabric. These results are shown in Table 4.

[0094]

[0095] Example 10 Except for using polyhexamethylene sevacamide (98% sulfuric acid relative viscosity: 2.70, melt viscosity: 700 poise, tip moisture content: 100 ppm, melting point: 220°C) as the sheath component, melt spinning was carried out in the same manner as in Example 1 to obtain 59dtex24 filament polyamide eccentric core sheath cross section fibers. For the obtained polyamide eccentric core sheath cross section fibers, the elongation rate, total fineness, single filament fineness, 15% stress, and elongation were measured. The number of yarn breaks when producing 1 ton of polyamide eccentric core sheath cross section fibers was also counted. These results are shown in Table 4.

[0096] The obtained polyamide eccentric core-sheath cross-section fibers were subjected to false-twist processing in the same manner as in Example 1, except that the processing temperature for false-twist processing was set to 170°C, to obtain false-twisted yarn with approximately 50 dtex 24 filaments. The total fineness, high-load stretch elongation rate, 15% stress, and elongation of the obtained false-twisted yarn were measured. These results are shown in Table 4.

[0097] The obtained false-twisted yarn was subjected to the same advanced processing as in Example 1 to obtain a fabric. The fabric stretch and colorfastness were measured for the obtained fabric. These results are shown in Table 4.

[0098] Example 11 Melt spinning was performed in the same manner as in Example 9, except that the cross-sectional shape was side-by-side, to obtain polyamide side-by-side cross-sectional fibers of 59dtex24 filament. For the obtained polyamide side-by-side cross-sectional fibers, the stretch elongation rate, total fineness, single filament fineness, 15% stress, and elongation were measured. The number of filament breaks when producing 1 ton of polyamide side-by-side cross-sectional fibers was also counted. These results are shown in Table 4.

[0099] The obtained polyamide side-by-side cross-section fibers were subjected to false-twist processing in the same manner as in Example 1 to obtain false-twisted yarn with approximately 50 dtex 24 filaments. The total fineness, high-load stretch elongation rate, 15% stress, and elongation of the obtained false-twisted yarn were measured. These results are shown in Table 4.

[0100] The obtained false-twisted yarn was subjected to the same advanced processing as in Example 1 to obtain a fabric. The fabric stretch and colorfastness were measured for the obtained fabric. These results are shown in Table 4.

[0101] Example 12: Melt spinning was performed in the same manner as in Example 4, except for the heat setting temperature, to obtain polyamide eccentric core-sheath cross-section fibers of 59dtex24 filament. For the obtained polyamide eccentric core-sheath cross-section fibers, the elongation rate under high load, total fineness, single filament fineness, 15% stress, and elongation were measured. The number of yarn breaks when producing 1 ton of polyamide eccentric core-sheath cross-section fibers was also counted. These results are shown in Table 5.

[0102] The obtained polyamide eccentric core-sheath cross-section fibers were used to create fabrics in the same manner as in Example 1, without false-twisting. The fabric stretch and colorfastness were measured for the obtained fabrics. These results are shown in Table 5.

[0103]

[0104] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications are possible without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2024-197095, filed on 12 November 2024, which is incorporated herein by reference in its entirety.

[0105] 1: Polyamide (A) 2: Polyamide (B) 3: Core component polyamide (A) 4: Sheath component polyamide (B)

Claims

A polyamide composite cross-section fiber consisting of two types of polyamides that satisfy the following conditions A to D. A. The composite morphology of the fiber cross-section is side-by-side or eccentric core-sheath type. B. 15% stress is 2.0–3.5 cN / dtex C. Elongation 20-40% D. The high-load stretching ratio E2 shown below is 7.0% or higher. A heat treatment load of total fineness × 5.4 (mg / dtex) × 20 × 2 is applied to a loop-shaped sack, and it is treated in hot water at a temperature of 99±1°C for 30 minutes. After that, the heat treatment load is removed and the sack is dried in an environment of 25°C, 60% humidity, and no load. An initial load of total fineness × 5.4 (mg / dtex) × 20 × 2 is applied to the dried sack, and the length (La) is measured after 90 seconds. The initial load is removed, and then a constant load of 90 (mg·dtex) × 20 × 2 is applied, and the length (Lb) is measured after 30 seconds. (Lb - La) / La × 100 (%) is defined as the high-load expansion and contraction ratio E2. 　 The polyamide composite cross-sectional fiber according to claim 1, wherein each of the two types of polyamide is composed of 95 mol% or more of one type of homopolyamide. 　 A polyamide composite cross-section fiber for false twisting, consisting of two types of polyamides that satisfy the following terms E to H. E. The composite morphology of the fiber cross-section is side-by-side or eccentric core-sheath type. F. 15% stress is 1.5–3.0 cN / dtex G. Elongation: Over 40% and under 80% H. The stretching / elongation ratio E1 shown below is 5.0% or higher. A heat treatment load of total fineness × 1.8 (mg / dtex) × 20 × 2 is applied to a loop-shaped sack, and it is treated in hot water at a temperature of 99±1°C for 30 minutes. After that, the heat treatment load is removed and the sack is dried in an environment of 25°C, 60% humidity, and no load. An initial load of total fineness × 1.8 (mg / dtex) × 20 × 2 is applied to the dried sack, and the length (L1) is measured after 90 seconds. The initial load is removed, and then a constant load of 90 (mg / dtex) × 20 × 2 is applied, and the length (L2) is measured after 30 seconds. (L2 - L1) / L1 × 100 (%) is defined as the stretching ratio E1. 　 A woven or knitted fabric made of polyamide composite cross-section fibers as described in claim 1 or polyamide composite cross-section fibers for false-twist processing as described in claim 3.

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