PA12-based side-by-side bicomponent ammonia-free elastic fiber and method for producing the same

Abstract

The application discloses a PA12-based parallel bicomponent ammonia-free elastic fiber and a preparation method thereof. The fiber is composed of a PA12 component and a PA6 component arranged in parallel along the fiber axis. The boiling water shrinkage of the PA12 component is less than that of the PA6 component, and the mass ratio of the two is 20:80-80:20. The preparation method comprises the following steps: vacuum drying PA12 chips and PA6 chips respectively, melting and extruding the PA12 chips and the PA6 chips through a screw partition, extruding the PA12 chips and the PA6 chips in a left-right parallel form in the same spinneret hole through a parallel composite spinning assembly, cooling through side blowing, collecting and oiling, and then performing post-treatment and shaping to obtain an elastic finished fiber with a three-dimensional spiral curling structure. The application utilizes the thermal shrinkage difference between PA12 and PA6 to form a permanent three-dimensional curling structure, endows the fiber with high resilience, and meanwhile, retains the soft hand feeling, moisture absorption and dyeing affinity of the polyamide material, and is ammonia-free and environmentally-friendly. The fiber can be used to prepare FDY or DTY products through a one-step method or a two-step method, and is suitable for the field of elastic textiles such as sportswear and underwear.

Description

Technical Field

[0001] This invention belongs to the field of differentiated polyamide fiber technology, and in particular to a PA12-based side-by-side bicomponent ammonia-free elastic fiber and its preparation method. Background Technology

[0002] Currently, elastic textiles have a wide range of applications in sportswear, underwear, swimwear, and medical care. Traditional high-elasticity textiles generally use spandex (polyurethane elastic fiber) covered yarn or spandex blended fabrics to achieve elasticity. However, the production and application of spandex have many inherent drawbacks: on the one hand, spandex raw materials are expensive, and it easily releases volatile amines during spinning and downstream dyeing and finishing processes, causing irritating pollution to the production environment and resulting in high environmental treatment costs; on the other hand, spandex has poor resistance to damp heat and washing performance, and its molecular chain structure is prone to irreversible damage after long-term use or high-temperature dyeing and finishing, leading to significant elasticity loss and severely restricting the service life and shape retention of the fabric.

[0003] To overcome the aforementioned shortcomings, significant progress has been made in ammonia-free elastic fiber technology in recent years. Among these advancements, polyester-based side-by-side bicomponent composite fibers, such as T400 (PTT / PET) and T800 (PBT / PET), utilize the difference in thermal shrinkage between the two components to form a three-dimensional helical crimp structure, thereby endowing the fiber with excellent elastic recovery properties and effectively avoiding many of the shortcomings of spandex. Nevertheless, existing ammonia-free elastic fibers are mostly limited to polyester systems, whose molecular chains are relatively rigid. There is still considerable room for improvement in terms of softness, moisture absorption and wicking properties, and the vibrancy of dark dyeing, making it difficult to meet the stringent requirements for skin-friendly comfort in high-end intimate textiles.

[0004] In contrast, polyamide fibers (such as PA6, PA66, and PA12), due to their molecular chains being rich in amide groups, naturally possess excellent softness, good moisture absorption, and outstanding dye affinity, making them ideal materials for developing high-end textile fabrics. However, a single polyamide component itself lacks sufficient elastic recovery capacity and cannot be directly used in the field of elastic fabrics. Therefore, this invention proposes a PA12-based side-by-side bicomponent ammonia-free elastic fiber, aiming to balance the comfort properties of polyamide with the requirements of elasticity. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned problems and provide a PA12-based side-by-side bicomponent ammonia-free elastic fiber and its preparation method.

[0006] The technical solution of this invention is: a PA12-based parallel bicomponent ammonia-free elastic fiber, comprising PA12 and PA6 components that extend continuously along the fiber axis and are arranged in parallel with each other. The fiber cross-section has a parallel structure, and its cross-sectional shape is crescent-shaped, orange-segment-shaped, or figure-eight-shaped. The boiling water shrinkage rate of the PA12 component is less than that of the PA6 component, and the difference in boiling water shrinkage rate between the PA12 and PA6 components is 5-20%. The mass ratio of the PA12 component to the PA6 component is 20:80 to 80:20. Within this ratio range, sufficient shrinkage difference can be ensured to produce significant crimp, while maintaining excellent mechanical properties and spinnability of the fiber. A ratio that is too high or too low may lead to insufficient crimping force or fiber performance imbalance. The area ratio of the PA12 component to the PA6 component on the fiber cross-section is (40-60):(60-40).

[0007] Preferably, the relative viscosity of the PA6 component is 2.0 to 3.4.

[0008] Preferably, the mass ratio of the PA12 component to the PA6 component is 30:70 to 70:30.

[0009] More preferably, the mass ratio of the PA12 component to the PA6 component is 40:60 to 60:40.

[0010] This invention also provides a method for preparing PA12-based side-by-side bicomponent ammonia-free elastic fibers, comprising the following steps:

[0011] Step (1) Pre-treatment of slice drying: PA12 slices and PA6 slices are vacuum dried separately. The PA12 slices are dried to a moisture content of ≤300ppm at a drying temperature of 80-110℃. The PA6 slices are dried to a moisture content of ≤200ppm at a drying temperature of 100-130℃.

[0012] Step (II) Screw-based zoned melt extrusion: The dried PA12 chips are added to the first screw extruder. Zones one through four are sequentially set along the material travel direction. The temperatures of zones one through four are controlled at 180–200℃, 190–210℃, 200–240℃, and 210–240℃, respectively. The temperature of the die head, metering pump, and pipelines of the first screw extruder is controlled at 220–240℃, the metering pump speed is controlled at 6–15 rpm, and the component pressure is controlled at 3. 0~10MPa; The dried PA6 chips are added to the second screw extruder, and zones one to four are set sequentially along the material travel direction. The temperatures of zones one to four are controlled at 230~250℃, 240~260℃, 250~280℃ and 250~280℃ respectively. The temperature of the die head and components of the second screw extruder is controlled at 250~280℃, the metering pump speed is controlled at 12~30rpm, and the component pressure is controlled at 7.5~8.0MPa.

[0013] Step (III) Parallel Composite Extrusion Molding: The PA12 melt extruded by the first screw extruder and the PA6 melt extruded by the second screw extruder in Step (II) are fed into the parallel composite spinning assembly by independent metering pumps at a mass ratio of PA12 component to PA6 component of 20:80 to 80:20. They are extruded in the same spinneret in a left-right parallel manner to obtain parallel nascent fibers. The parallel nascent fibers are cooled by side blowing and bundled and oiled. The temperature of the side blowing is 12 to 16°C and the air pressure is 20 to 30 Pa.

[0014] Step (iv) Post-treatment and shaping: The nascent fibers after oiling in step (iii) are post-treated and shaped to give them a three-dimensional spiral crimp structure in an unstretched state, thus obtaining an elastic finished fiber. The single filament fineness of the finished fiber is 0.5 to 5.0 dtex.

[0015] Specifically, in step (iv): the post-treatment setting is a one-step high-speed drawing and heat setting method. The nascent fiber bundles after oiling in step (iii) are sequentially drawn and set online through the first hot roller and the second hot roller. The temperature of the first hot roller is 40-60℃ and the surface linear speed is 1000-4000m / min; the temperature of the second hot roller is 120-160℃ and the surface linear speed is 2000-6000m / min; the winding speed is controlled at 2000-6000m / min and the total draw ratio is 1.6-2.8; the fiber forms a stable three-dimensional helical crimp structure through online drawing and heat setting, and FDY fiber is obtained after winding.

[0016] Furthermore, in the above-mentioned method for preparing PA12-based side-by-side bicomponent ammonia-free elastic fibers, the physical properties of the FDY fibers are: elastic recovery rate of 88%–95%, boiling water shrinkage rate of 28%–36%, breaking strength of 3.9–5.0 cN / dtex, and breaking elongation of 15%–40%.

[0017] Specifically, in step (iv): the post-treatment setting is a two-step pre-orientation-texturing setting method. The filament bundle after oiling in step (iii) is directly wound to form POY pre-oriented yarn at a winding speed of 2700-4000 m / min. The obtained POY pre-oriented yarn is sent to a texturing machine for false twist setting, with the draw ratio controlled at 1.2-1.6, the false twist ratio at 1.6-2.4, the heating temperature of the hot box at 120-160℃, and the pressure of the network nozzle at 0.1-0.3 MPa. After texturing setting, DTY fiber is obtained.

[0018] Furthermore, in the above-mentioned method for preparing PA12-based side-by-side bicomponent ammonia-free elastic fibers, the physical properties of the DTY fibers are: elastic recovery rate of 90%–97%, breaking strength of 3.0–4.5 cN / dtex, and breaking elongation of 25%–50%; and the DTY fibers have micro-web, light web, medium web, or heavy web structures, wherein the network node density of the micro-web structure is 20–40 nodes / m; the network node density of the light web structure is 40–90 nodes / m; the network node density of the medium web structure is 90–100 nodes / m; and the network node density of the heavy web structure is 100–120 nodes / m.

[0019] Compared with the prior art, the technical solution of this invention has the following technical effects:

[0020] (i) This invention uses only the PA12 / PA6 bispolyamide system, and no spandex elastic component needs to be added throughout the entire process. There is no ammonia release from spinning to downstream dyeing and finishing, which fundamentally avoids the nitrogen oxide pollution problem of ammonia-containing fabrics in the dyeing and finishing process, significantly reduces the cost of end-of-pipe environmental protection treatment, and meets the requirements of clean production.

[0021] (II) This invention utilizes the differentiated heat shrinkage behavior between PA12 and PA6 components to form a stable three-dimensional helical crimp structure within the fiber. After repeated washing and external stretching, the crimp shape retention rate of the FDY and DTY finished fibers is significantly better than that of conventional PA6 composite yarns, effectively overcoming the traditional tensile elasticity loss defect. Among them, the highest elastic recovery rate of DTY fiber can reach 97.6%, exhibiting excellent elastic durability.

[0022] (III) The introduction of PA12 component in this invention effectively improves the moisture absorption and flexibility of the fiber. The finished fabric does not have the "plastic feel" and stiffness of polyester fiber or conventional nylon. It has excellent skin-friendliness and close-fitting comfort, and is especially suitable for the development of underwear, sports yoga wear and high-end close-fitting knitted fabrics.

[0023] (iv) The FDY process of the present invention can be configured with a non-net or light net structure as needed to meet the requirements of different weaving styles; the DTY process can flexibly control the net degree level (micro net / light net / medium net / heavy net), crimp loft and breaking elongation by independently adjusting the net nozzle pressure, hot box temperature and draft ratio, and can accurately adapt to diversified processing scenarios such as woven weaving, warp knitting and circular knitting.

[0024] (v) The present invention can flexibly select either the one-step FDY short process or the two-step DTY high-fluff process according to the product positioning and downstream application scenarios, which has the dual advantages of efficient production and high value-added product development, and enhances process adaptability and market response speed. Attached Figure Description

[0025] Figure 1 This is a cross-sectional view of the oil-free filament of the PA12-based parallel bicomponent ammonia-free elastic fiber of the present invention;

[0026] Figure 2 This is a structural diagram of the FDY fiber of the present invention;

[0027] Figure 3 This is a structural diagram of the DTY fiber of the present invention. Detailed Implementation

[0028] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments to make it easier to grasp. It should be understood that these embodiments are intended to facilitate understanding of the content of the present invention and are not intended to limit the scope of protection of the present invention in any way. Various equivalent substitutions, modifications, or variations made by those skilled in the art based on the disclosure of this specification should fall within the protection scope of the appended claims.

[0029] Example 1

[0030] like Figure 1 and Figure 2 As shown in Example 1, the preparation method of PA12-based side-by-side bicomponent ammonia-free elastic FDY fiber includes the following specific steps:

[0031] (1) Raw material pretreatment

[0032] PA12 slices were placed in a vacuum drying apparatus and dried at 105℃ and 80Pa for 12 hours to obtain PA12 slices with a water content of 200ppm. PA6 slices with a relative viscosity of 2.4 were also dried at 105℃ and 80Pa for 12 hours to obtain PA6 slices with a water content of 230ppm.

[0033] (2) Melt extrusion and composite spinning

[0034] The dried PA12 chips are added to the first screw extruder. The temperatures of each heating zone are set as follows: Zone 1 200℃, Zone 2 210℃, Zone 3 220℃, and Zone 4 220℃. The die head, metering pump, and pipeline temperatures are all controlled at 220℃, the metering pump speed is 9 rpm, and the component pressure is 6.5 MPa. The dried PA6 chips are added to the second screw extruder. The temperatures of each heating zone are set as follows: Zone 1 240℃, Zone 2 250℃, Zone 3 265℃, and Zone 4 270℃. The die head and component temperatures are controlled at 270℃, the metering pump speed is 18 rpm, and the component pressure is 7.8 MPa. The two melt streams are fed into a parallel composite spinning assembly via independent metering pumps at a PA12 chip to PA6 chip mass ratio of 50:50. The spinneret has 48 holes arranged in a figure-eight pattern, allowing the two melt components to be extruded side-by-side within the same spinneret. The extruded nascent fibers are cooled and shaped by side blowing air at a temperature of 14°C and a pressure of 25Pa; then they are bundled and oiled.

[0035] (3) FDY online drawing and setting

[0036] The oiled filament bundles are sequentially passed through a first hot roller (GR1) and a second hot roller (GR2) for two-stage online drawing and heat setting. GR1 is set at 50℃ with a surface linear velocity of 1800 m / min; GR2 is set at 145℃ with a surface linear velocity of 3600 m / min; the total draw ratio is 2.0. The drawn and set fibers are then wound into a cake at a winding speed of 3600 m / min, yielding PA12-based side-by-side bicomponent ammonia-free elastic FDY fiber.

[0037] The FDY fibers prepared in Example 1 were subjected to performance and dyeing tests, and the results are shown in Tables 1 and 2.

[0038] Example 2

[0039] This embodiment 2 provides a method for preparing PA12-based side-by-side bicomponent ammonia-free elastic FDY fiber. The difference between this method and that of Embodiment 1 lies in the number of spinneret holes and some spinning process parameters. The specific steps are as follows:

[0040] (1) Raw material pretreatment

[0041] PA12 slices were placed in a vacuum drying apparatus and dried at 105℃ and 80Pa for 12 hours to obtain PA12 slices with a water content of 200ppm. PA6 slices with a relative viscosity of 2.4 were also dried at 105℃ and 80Pa for 12 hours to obtain PA6 slices with a water content of 230ppm.

[0042] (2) Melt extrusion and composite spinning

[0043] The dried PA12 chips are fed into the first screw extruder. The temperatures of each heating zone are set as follows: Zone 1 200℃, Zone 2 210℃, Zone 3 220℃, and Zone 4 220℃. The die head, metering pump, and pipeline temperatures are all controlled at 220℃. The metering pump speed is 8 rpm, and the component pressure is 5.5 MPa. The dried PA6 chips are fed into the second screw extruder. The temperatures of each heating zone are set as follows: Zone 1 240℃, Zone 2 250℃, Zone 3 265℃, and Zone 4 270℃. The die head and component temperatures are controlled at 270℃. The metering pump speed is 16 rpm, and the component pressure is 8.8 MPa. The two melt streams are fed into a parallel composite spinning assembly via independent metering pumps at a PA12 chip to PA6 chip mass ratio of 50:50. The spinneret has 24 holes arranged in a figure-eight pattern, allowing the two melt components to be extruded side-by-side within the same spinneret. The extruded nascent fibers are cooled and shaped by side blowing air at a temperature of 14°C and a pressure of 25Pa; then they are bundled and oiled.

[0044] (3) FDY online drawing and setting

[0045] The oiled filament bundle is sequentially passed through a first hot roller (GR1) and a second hot roller (GR2) for two-stage online drawing and heat setting. GR1 is set at 50℃ with a surface linear velocity of 1800 m / min; GR2 is set at 145℃ with a surface linear velocity of 3600 m / min; the total draw ratio is 2.0. The drawn and set fibers are then wound into a cake at a winding speed of 3600 m / min, yielding PA12-based side-by-side bicomponent ammonia-free elastic FDY finished fiber.

[0046] The FDY fibers prepared in Example 2 were subjected to performance and dyeing tests, and the results are shown in Tables 1 and 2.

[0047] Example 3

[0048] This embodiment 3 provides a method for preparing PA12-based side-by-side bicomponent ammonia-free elastic FDY fiber. The difference between this method and embodiments 1 and 2 is that the PA6 component uses higher viscosity chips, and the spinning temperature and side-blowing process parameters are adjusted accordingly. The specific steps are as follows:

[0049] (1) Raw material pretreatment

[0050] PA12 slices were placed in a vacuum drying apparatus and dried at 105℃ and 80Pa for 12 hours to obtain PA12 slices with a water content of 200ppm. PA6 slices with a relative viscosity of 3.2 were also dried at 105℃ and 80Pa for 12 hours to obtain PA6 slices with a water content of 230ppm.

[0051] (2) Melt extrusion and composite spinning

[0052] The dried PA12 chips are fed into the first screw extruder. The temperatures of each heating zone are set as follows: Zone 1 200℃, Zone 2 210℃, Zone 3 220℃, and Zone 4 220℃. The die head, metering pump, and pipeline temperatures are all controlled at 220℃. The metering pump speed is 9 rpm, and the component pressure is 5.9 MPa. The dried PA6 chips are fed into the second screw extruder. The temperatures of each heating zone are set as follows: Zone 1 250℃, Zone 2 260℃, Zone 3 275℃, and Zone 4 275℃. The die head and component temperatures are controlled at 275℃. The metering pump speed is 18 rpm, and the component pressure is 8.7 MPa. The two melt streams are fed into a parallel composite spinning assembly via independent metering pumps at a PA12 chip to PA6 chip mass ratio of 50:50. The spinneret has 48 holes arranged in a figure-eight pattern, allowing the two melt components to be extruded side-by-side within the same spinneret. The extruded nascent fibers are cooled and shaped by side blowing air at a temperature of 12°C and a pressure of 50Pa; then they are bundled and oiled.

[0053] (3) FDY online drawing and setting

[0054] The oiled filament bundle is sequentially passed through a first hot roller (GR1) and a second hot roller (GR2) for two-stage online drawing and heat setting. GR1 is set at 50℃ with a surface linear velocity of 1800 m / min; GR2 is set at 145℃ with a surface linear velocity of 3600 m / min; the total draw ratio is 2.0. The drawn and set fibers are then wound into a cake at a winding speed of 3600 m / min, yielding PA12-based side-by-side bicomponent ammonia-free elastic FDY finished fiber.

[0055] The FDY fibers obtained in Example 3 were subjected to performance and dyeing tests, and the results are shown in Tables 1 and 2.

[0056] Example 4

[0057] like Figure 3 As shown in Example 4, this method for preparing PA12-based side-by-side bicomponent ammonia-free elastic DTY fiber employs a two-step process: first, POY pre-oriented yarn is prepared, and then the DTY finished fiber is obtained through texturing and setting. The specific steps are as follows:

[0058] (1) Raw material pretreatment

[0059] PA12 slices were placed in a vacuum drying apparatus and dried at 105℃ and 80Pa for 12 hours to obtain PA12 slices with a water content of 200ppm. PA6 slices with a relative viscosity of 2.4 were also dried at 105℃ and 80Pa for 12 hours to obtain PA6 slices with a water content of 230ppm.

[0060] (2) Melt extrusion and composite spinning

[0061] The dried PA12 chips are added to the first screw extruder. The temperatures of each heating zone are set as follows: Zone 1 200℃, Zone 2 210℃, Zone 3 220℃, and Zone 4 220℃. The die head, metering pump, and pipeline temperatures are all controlled at 220℃, the metering pump speed is 9 rpm, and the component pressure is 6.5 MPa. The dried PA6 chips are added to the second screw extruder. The temperatures of each heating zone are set as follows: Zone 1 240℃, Zone 2 250℃, Zone 3 265℃, and Zone 4 270℃. The die head and component temperatures are controlled at 270℃, the metering pump speed is 18 rpm, and the component pressure is 7.8 MPa. The two melt streams are fed into a parallel composite spinning assembly via independent metering pumps at a PA12 chip to PA6 chip mass ratio of 50:50. The spinneret has 48 holes arranged in a figure-eight pattern, allowing the two melt components to be extruded side-by-side within the same spinneret. The extruded nascent fibers are cooled and shaped by side blowing air at a temperature of 14°C and a pressure of 25Pa; then they are bundled and oiled.

[0062] (3) POY spinning

[0063] The cooled and oiled filament bundles were directly wound at a winding speed of 3200 m / min to obtain PA12 / PA6 parallel composite POY pre-oriented yarn.

[0064] (4) DTY elastic shaping

[0065] The POY pre-oriented yarn is fed into a texturing machine for false twisting texturing. The machine speed is 500 m / min, the draw ratio is 1.3, the false twist ratio is 2.0, the hot box temperature is 150℃, the hot plate temperature is 140℃, and the network nozzle pressure is 0.15 MPa. After texturing and setting, it is wound into a yarn bobbin to obtain PA12-based side-by-side bicomponent ammonia-free elastic DTY finished fiber.

[0066] The DTY fibers obtained in Example 4 were subjected to performance and dyeing tests, and the results are shown in Tables 1 and 2.

[0067] Example 5

[0068] Example 5 provides another method for preparing PA12-based side-by-side bicomponent ammonia-free elastic DTY fiber. The difference between this method and Example 4 is the use of a higher viscosity PA6 component, and corresponding adjustments to the spinning temperature, side-blowing conditions, and texturing process parameters. The specific steps are as follows:

[0069] (1) Raw material pretreatment

[0070] PA12 slices were placed in a vacuum drying apparatus and dried at 105℃ and 80Pa for 12 hours to obtain PA12 slices with a water content of 200ppm. PA6 slices with a relative viscosity of 3.2 were also dried at 105℃ and 80Pa for 12 hours to obtain PA6 slices with a water content of 200ppm.

[0071] (2) Melt extrusion and composite spinning

[0072] The dried PA12 chips are fed into the first screw extruder. The temperatures of each heating zone are set as follows: Zone 1 200℃, Zone 2 210℃, Zone 3 220℃, and Zone 4 220℃. The die head, metering pump, and pipeline temperatures are all controlled at 220℃. The metering pump speed is 9 rpm, and the component pressure is 6.5 MPa. The dried PA6 chips are fed into the second screw extruder. The temperatures of each heating zone are set as follows: Zone 1 250℃, Zone 2 260℃, Zone 3 275℃, and Zone 4 275℃. The die head and component temperatures are controlled at 275℃. The metering pump speed is 18 rpm, and the component pressure is 8.7 MPa. The two melt streams are fed into a parallel composite spinning assembly via independent metering pumps at a PA12 chip to PA6 chip mass ratio of 50:50. The spinneret has 48 holes arranged in a figure-eight pattern, allowing the two melt components to be extruded side-by-side within the same spinneret. The extruded nascent fibers are cooled and shaped by side blowing air at a temperature of 12°C and a pressure of 50Pa; then they are bundled and oiled.

[0073] (3) POY spinning

[0074] The cooled and oiled filament bundles were directly wound at a winding speed of 3200 m / min to obtain PA12 / PA6 parallel composite POY pre-oriented yarn.

[0075] (4) DTY elastic shaping

[0076] The POY pre-oriented yarn is fed into a texturing machine for false twisting texturing. The machine speed is 500 m / min, the draw ratio is 1.35, the false twist ratio is 2.2, the hot box temperature is 160℃, the hot plate temperature is 140℃, and the network nozzle pressure is 0.2 MPa. After texturing and setting, it is wound into a yarn bobbin to obtain PA12-based side-by-side bicomponent ammonia-free elastic DTY finished fiber.

[0077] The DTY fibers obtained in Example 5 were subjected to performance and dyeing tests, and the results are shown in Tables 1 and 2.

[0078]

[0079] As shown in Table 1, the fineness of Examples 1 to 5 covers 50 to 60 dtex, and the breaking strength is stable at 4.01 to 4.89 cN / dtex, indicating a solid mechanical foundation. The elongation at break has a wide gradient, which can be adapted to fabrics with different stretching requirements. The elastic recovery rate is ≥87.10%, and the fabric has outstanding wrinkle resistance and shape retention. The dry heat shrinkage rate is controllable, the dimensional stability at high temperature is good, and the adjustable range of crimp-related indicators is wide. It can be adapted to a variety of products such as wear-resistant flat fabrics and high-loft elastic fabrics, with balanced comprehensive performance and strong customization adaptability.

[0080] The FDY / DTY fibers prepared in Examples 1-5 were dyed with acid dyes at a liquor ratio of 1:30, a concentration of 3wt%, and a pH of 4. The color fastness to rubbing was measured according to GB / T3920-2008, and the results are shown in Table 2.

[0081]

[0082] As shown in Table 2, Examples 1 to 5 all have a high dyeing percentage and high dye utilization rate; the K / S value of the samples is maintained at a high level, the apparent color depth of the fabric is sufficient, and the dye utilization rate is high; the ΔE value is small, the dyeing color difference is low, and the color uniformity of the fabric is good; the dry and wet rubbing fastness of each sample is stable at grade 4 to 5, the color fastness performance is excellent, and the overall dyeing effect is ideal.

[0083] Thus, by adopting the technical solution of this invention, parallel bicomponent composite spinning technology is innovatively introduced into the polyamide system. PA12 and PA6 are used as raw materials, and the inherent thermal shrinkage difference between the two is utilized to carry out parallel composite spinning. During the subsequent wet heat treatment (such as dyeing and setting), the two components generate uneven shrinkage stress due to their different shrinkage rates, which causes the fiber to twist along the longitudinal axis, thereby forming a permanent three-dimensional helical crimp structure.

[0084] As can be seen from the above description, compared with the prior art, the technical solution of this invention has a physical curling mechanism similar to a spring, which not only endows the fiber with long-lasting and stable high resilience, effectively overcoming the defects of spandex being easy to age and having rapid elasticity decay, but also perfectly retains the inherent soft hand feel, excellent moisture absorption and excellent dyeing affinity of polyamide materials, thus successfully developing a new type of ammonia-free elastic fiber that combines high elasticity, comfort and dyeing performance.

[0085] The technical solution, working process, and implementation effects of the present invention have been described in detail above. It should be noted that the described examples are only typical examples of the present invention. In addition, the present invention may have many other specific implementation methods. All technical solutions formed by equivalent substitution or equivalent transformation fall within the scope of protection claimed by the present invention.

Claims

1. A PA12-based side-by-side bicomponent ammonia-free elastic fiber, characterized in that: It includes PA12 and PA6 components that extend continuously along the fiber axis and are arranged in parallel to each other. The cross-section of the fiber has a parallel structure, and its cross-sectional shape is crescent-shaped, orange-segment-shaped, or figure-eight-shaped. The boiling water shrinkage rate of the PA12 component is less than that of the PA6 component, and the difference between the boiling water shrinkage rates of the PA12 component and the PA6 component is 5% to 20%. The mass ratio of PA12 component to PA6 component is 20:80 to 80:20; The area ratio of the PA12 component to the PA6 component on the fiber cross-section is (40-60):(60-40).

2. The PA12-based side-by-side bicomponent ammonia-free elastic fiber according to claim 1, characterized in that: The mass ratio of PA12 component to PA6 component is 30:70 to 70:

30.

3. The PA12-based side-by-side bicomponent ammonia-free elastic fiber according to claim 2, characterized in that: The mass ratio of PA12 component to PA6 component is 40:60 to 60:

40.

4. The PA12-based side-by-side bicomponent ammonia-free elastic fiber according to claim 1, characterized in that: The relative viscosity of the PA6 component is 2.0 to 3.

4.

5. A method for preparing a PA12-based side-by-side bicomponent ammonia-free elastic fiber, comprising the following steps: Step S1: Pre-treatment of slicing and drying PA12 slices and PA6 slices were vacuum dried separately. The PA12 slices were dried to a moisture content of ≤300ppm at a drying temperature of 80-110℃. The PA6 slices were dried to a moisture content of ≤200ppm at a drying temperature of 100-130℃. Step S2: Screw-driven zoned melt extrusion The dried PA12 chips are fed into the first screw extruder, and zones one through four are set sequentially along the material travel direction. The temperatures of zones one through four are controlled at 180–200℃, 190–210℃, 200–240℃, and 210–240℃, respectively. The temperature of the die head, metering pump, and pipeline of the first screw extruder is controlled at 220–240℃, the metering pump speed is controlled at 6–15 rpm, and the component pressure is controlled at 3.0–10 MPa. The dried PA6 chips are fed into the second screw extruder, and zones one through four are set sequentially along the material travel direction. The temperatures of zones one through four are controlled at 230–250℃, 240–260℃, 250–280℃, and 250–280℃, respectively. The temperature of the die head and components of the second screw extruder is controlled at 250–280℃, the metering pump speed is controlled at 12–30 rpm, and the component pressure is controlled at 7.5–8.0 MPa. Step S3: Parallel compound extrusion molding The PA12 melt extruded by the first screw extruder and the PA6 melt extruded by the second screw extruder in S2 are fed into a parallel composite spinning assembly by independent metering pumps at a mass ratio of PA12 component to PA6 component of 20:80 to 80:

20. They are extruded in the same spinneret in a left-right parallel form to obtain parallel nascent fibers. The parallel nascent fibers are cooled by side blowing and bundled and oiled. The temperature of the side blowing is 12 to 16°C and the air pressure is 20 to 30 Pa. Step S4: Post-processing and shaping The nascent fibers after oiling in step S3 are post-treated and shaped to give them a three-dimensional spiral crimp structure in their unstretched state, thus obtaining an elastic finished fiber. The single filament fineness of the finished fiber is 0.5 to 5.0 dtex.

6. The method for preparing PA12-based side-by-side bicomponent ammonia-free elastic fiber according to claim 5, characterized in that, In step S4: the post-treatment setting is a one-step high-speed drawing and heat setting method. The nascent fiber bundle after oiling in step S3 is sequentially passed through a first hot roller and a second hot roller for online drawing and setting. The temperature of the first hot roller is 40-60℃ and the surface linear speed is 1000-4000m / min; the temperature of the second hot roller is 120-160℃ and the surface linear speed is 2000-6000m / min; the winding speed is controlled at 2000-6000m / min and the total drawing ratio is 1.6-2.8; the online drawing and heat setting makes the fiber form a stable three-dimensional helical crimp structure, and the FDY fiber is obtained after winding.

7. The method for preparing PA12-based side-by-side bicomponent ammonia-free elastic fiber according to claim 6, characterized in that: The physical properties of the FDY fiber are: elastic recovery rate of 88% to 95%, boiling water shrinkage rate of 28% to 36%, breaking strength of 3.9 to 5.0 cN / dtex, and breaking elongation of 15% to 40%.

8. The method for preparing PA12-based side-by-side bicomponent ammonia-free elastic fiber according to claim 5, characterized in that, In step S4: the post-treatment setting is a two-step pre-orientation-texturing setting method. The filament bundle after oiling in step S3 is directly wound to form POY pre-oriented yarn at a winding speed of 2700-4000 m / min. The obtained POY pre-oriented yarn is fed into a texturing machine for false twist setting, with the draw ratio controlled at 1.2-1.6, the false twist ratio at 1.6-2.4, the heating temperature in the hot box at 120-160℃, and the pressure of the network nozzle at 0.1-0.3 MPa. After texturing setting, DTY fiber is obtained.

9. The method for preparing PA12-based side-by-side bicomponent ammonia-free elastic fiber according to claim 8, characterized in that: The physical properties of the DTY fiber are: elastic recovery rate of 90% to 97%, breaking strength of 3.0 to 4.5 cN / dtex, and breaking elongation of 25% to 50%.

10. The method for preparing PA12-based side-by-side bicomponent ammonia-free elastic fiber according to claim 9, characterized in that: The DTY fiber has a micro-web, light web, medium web, or heavy web structure. The network node density of the micro-web structure is 20-40 nodes / m; the network node density of the light web structure is 40-90 nodes / m; the network node density of the medium web structure is 90-100 nodes / m; and the network node density of the heavy web structure is 100-120 nodes / m.

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