Preparation method of nylon bicomponent self-curling elastic fiber

Abstract

The present application provides a method for preparing a nylon two-component self-curling elastic fiber, which belongs to the technical field of polyamide filament manufacturing methods. Modified PA66 polymer chips are used as raw materials, and the main spinning melt is obtained by drying, extrusion and melting. Nylon 6 chips are used as raw materials, and the secondary spinning melt is obtained by drying, extrusion and melting. The main and secondary spinning melts enter the channels in the main and secondary boxes respectively, and are metered into the spinning assembly according to the volume ratio of 50-65:50-35. The main and secondary melts are eccentrically combined and spun between the distribution plate and the spinneret of the spinning assembly, and then subjected to side-blowing cooling, monomer suction and discharge, oiling, pre-humidification balance, drawing, hot plate setting, and winding to obtain the finished product. The present application is used for the preparation of two-component nylon self-curling elastic fibers, which have the advantages of excellent elasticity and significant curling.

Description

Technical Field

[0001] The present application relates to a method for preparing a nylon two-component self-curling elastic fiber, belonging to the technical field of polyamide filament manufacturing methods. Background Art

[0002] Two-component composite elastic fibers are primarily polyester, such as T400&T800 and T800, two of the more mature products on the market. T400&T800D is made from PTT+PET, primarily containing FDY; T800 is made from PBT+PET, primarily containing DTY. These two products not only exhibit excellent resilience but also address issues such as high dyeing temperatures, excess elasticity, dimensional instability, and aging associated with storage in traditional spandex yarns. They can be directly woven, significantly reducing the production cycle and manufacturing costs of elastic fibers. However, their drawback is the parallel construction of the composite, with both materials completely exposed. This makes dyeing uniformity difficult due to their respective properties, resulting in a high probability of color variation. Furthermore, they cannot compare to nylon in terms of moisture absorption, abrasion resistance, and softness.

[0003] Current research is mostly focused on composite fibers. For example, CN104651962A uses polyester and bio-based nylon 56 to form a hollow curly composite fiber; CN101586269A uses ordinary PET polyester as the core layer and PA as the sheath layer to form a core-skin composite fiber; and there are no mature products using nylon as the raw material to produce parallel elastic fibers.

[0004] CN105887218A uses copolymerized bright-chip nylon 6 and nylon 66 as raw materials to spin nylon high-shrinkage fiber. This adopts single-component spinning and cannot form the three-dimensional curling elastic effect produced by the different thermal shrinkage of the two components in composite spinning; CN109355716A combines nylon 6 and nylon 66 into elastic fiber FDY. The two materials in the resulting composite fiber have a parallel structure and the same color difference problem caused by the different color absorption rates of different materials. The different viscosities of the two raw materials also limit the curling elasticity of the finished product; CN104975362A combines a high-shrinkage component and a nylon component to form a split-flap FDY, but it is also a nylon-polyester composite and has weak curling elasticity. Summary of the Invention

[0005] In view of this, the present application provides a method for preparing nylon two-component self-curling elastic fibers, which not only realizes the elastic fiber processing of pure nylon components, but also gives the obtained fibers high elasticity and three-dimensional curling effects.

[0006] Specifically, this application is implemented through the following solutions:

[0007] A method for preparing a nylon bicomponent self-curling elastic fiber comprises the following steps:

[0008] The modified PA66 polymer chips are used as raw materials, and the main spinning melt is obtained by drying, extruding and melting. The nylon 6 chips are used as raw materials, and the secondary spinning melt is obtained by drying, extruding and melting.

[0009] The main and auxiliary spinning melts enter the channels in the main and auxiliary boxes respectively, and are metered into the spinning assembly according to a volume ratio of 50-65:50-35. The main and auxiliary melts are eccentrically combined and spun between the distribution plate and the spinneret of the spinning assembly. The pre-oriented yarn is then cooled by side blowing, the monomer is sucked and discharged, and oiled.

[0010] The pre-oriented yarn is subjected to pre-humidification balance, drafting, hot plate setting, and winding to obtain the finished product of bicomponent nylon self-curling elastic fiber;

[0011] The relative viscosity of the modified PA66 polymer chips is 3.5-3.7, and the relative viscosity of the nylon 6 chips is 2.2-2.45;

[0012] The pre-humidity balance refers to the pre-oriented yarn being conditioned for 8 to 24 hours in a constant temperature and humidity environment of 20 to 25°C and 50 to 60% humidity.

[0013] The drawing refers to: under the conditions of pre-tension of 0.05-0.2 cN / dtex and tension stabilization weight of 0.02-0.2 g / dtex, drawing is completed through a pressure roller and a hot roller.

[0014] In this scheme, the raw materials used are high-shrinkage modified PA66 polymer and low-viscosity PA6. The high-shrinkage modified PA66 polymer has a relative viscosity of 3.50-3.70, while the low-viscosity PA6 has a relative viscosity of 2.20-2.45. Not only do these two have a significant viscosity difference, but high-shrinkage chips are also used. The main and secondary spinning melts are first extruded and melted separately, and then the sheath-core composite is formed. The fibers are then cooled, oiled, pre-conditioned, and drawn and wound to produce the nylon bicomponent three-dimensional crimped elastic fiber. Pre-conditioning and balancing eliminate some internal stress in the POY, reducing adhesion between yarn layers and facilitating subsequent unwinding and drawing. The finished yarn is then processed through a creel, tension regulator, tension stabilizing plate, pressure roller, hot plate, hot plate setting, cooling plate, and winder. The yarn is drawn through the speed difference between the pressing roller and the hot plate. The drawn yarn is shaped by the hot plate between the hot plate and the cold plate, which stabilizes the yarn drawing to form an internal stress spiral structure, making the finished bicomponent nylon high-elastic yarn in a straight yarn state. The high-temperature processing destroys the internal stress balance of the fiber, forming a spiral three-dimensional curling structure, which makes the finished product have excellent elasticity.

[0015] Furthermore, as a preference:

[0016] In the eccentric sheath-core composite process, the primary spinning melt forms the core layer, while the secondary spinning melt forms the sheath layer. The eccentric core layer is partially exposed at a central angle of 20-60°. The composite of the two melts utilizes an eccentric sheath-core structure, with the core layer being a high-shrinkage modified PA66 polymer and the sheath layer being low-viscosity PA6 chips. The eccentric core layer is partially exposed at a central angle of 20-60°. This ensures the three-dimensional curling elasticity created by the different thermal shrinkage rates of the two materials. Furthermore, since the high-shrinkage modified PA66 polymer is nearly completely covered by the low-viscosity PA6, dyeing only requires consideration of the PA6 dyeing process, eliminating color differences caused by the performance differences between the two materials.

[0017] The drying process of the high-shrinkage modified PA66 polymer is as follows: the slices are dried by heating with dry air having a dew point temperature of ≤-50°C, the heating temperature is 70-100°C, the heating time is 2-6 hours, and the moisture content of the slices after drying is 600±100ppm; the drying process of the low-viscosity PA6 slices is as follows: the slices are dried by heating with dry air having a dew point temperature of ≤-50°C, the heating temperature is 80-110°C, the heating time is 6-10 hours, and the moisture content of the slices after drying is ≤200ppm.

[0018] During the melting process of the high-shrinkage modified PA66 polymer chips, the main box is heated by biphenyl steam at a temperature of 285-300°C, the melt residence time is controlled at ≤12 minutes, and the heating temperature of the screw extruder is controlled in five sections. The temperature setting starts from the feed section and increases from low to high, with a temperature of 285-305°C and a melt pressure of 120 MPa.

[0019] During the melting process of the low-viscosity PA6 chips, the auxiliary box is also heated by biphenyl steam, with a heating temperature of 260-280°C. The heating temperature of the screw extruder is controlled in 5 zones, and the temperature setting starts from the feed section from high to low, with a temperature of 285-260°C and a melt pressure of 120 MPa.

[0020] The wind speed of the monomer suction and discharge port is ≥5m / min, and the monomers in the suction and discharge pipes are regularly flushed every 15 to 30 days, and the flushed materials are filtered and recycled.

[0021] In the oiling process, the oil concentration is adjusted to 5%, two oil nozzles are set for oiling, and the elevation angle of the oil nozzle to the tow is 10-15 degrees.

[0022] The side-blowing cooling temperature is 20-25° C., and the wind speed is 0.35-0.60 m / sec.

[0023] In the drafting process, pre-moisturized and balanced POY is placed on a creel, drawn out, and sequentially passed through a tension adjuster and a tension stabilizer. The tension adjuster pre-tensions the POY to 0.05-0.2 cN / dtex, and the tension stabilizer counterweights 0.02-0.2 g / dtex. The POY then enters a press roller and a hot plate for drafting, achieving a draft ratio of 2-4. The POY is then shaped on a hot plate and wound by a winder to yield the finished product. This drafting process is suitable for drafting nylon bicomponent POY fibers, resolving the difficulty of unwinding and drafting nylon bicomponent POY fibers. It is also suitable for winding tubes caused by uneven unwinding tension in other elastic fibers.

[0024] in:

[0025] The tension regulator is composed of one or several groups of tension rods. The fiber passes through the tension rods. By adjusting the distance between the tension rods, the angle between the fiber and the tension rods is controlled, thereby achieving tension adjustment.

[0026] The tension stabilizing plate is composed of a gravity pendulum. When the fiber tension is uniform, the pendulum is lifted to a certain height by the fiber. When the fiber tension relaxes instantaneously, the pendulum slides on the fiber under the action of gravity and drives the fiber to fall, thereby buffering the phenomenon of fiber winding around the tube caused by the relaxation of the fiber tension.

[0027] The POY is wound around the pressing roller for 1 to 10 turns, and more preferably, the POY is wound around the pressing roller for 2 to 3 turns, which can effectively prevent the fiber from slipping.

[0028] The POY is wound on the hot plate for 1 to 10 turns, more preferably 6 to 8 turns, to preheat the fiber.

[0029] The temperature of the hot plate is 50-60°C.

[0030] The drafting ratio is 2.5 to 3.5.

[0031] The hot plate setting temperature is 100-130°C.

[0032] The winding speed is 3000-4500 m / min, and the winding tension is preferably controlled at 6-15g for fine denier and porous fibers, and ≥12g for coarse denier and less porous fibers. The network pressure is ≥0.2 MPa. The oil mist generated by the compressed air is extracted for oil-gas separation. The godet speed is overfed for fine denier and porous fibers, and underfed for coarse denier and less porous fibers. This produces a nylon composite three-dimensional crimped elastic fiber with low production cost and easy color absorption.

[0033] Beneficial effects of this application:

[0034] (1) The two-component nylon self-curling elastic material in this case is made of high shrinkage modified PA66 polymer and low viscosity PA6. The two raw materials not only have a large difference in viscosity, but also use high shrinkage slices. Combined with the extrusion, spinning and winding settings of this case, the finished product has a higher three-dimensional curling elastic effect.

[0035] (2) In this case, the two melt composites adopt an eccentric skin-core structure. The core layer is a high-shrinkage modified PA66 polymer, and the skin layer is a low-viscosity PA6 slice. The core layer is partially exposed, which ensures the three-dimensional curling elasticity produced by the different thermal shrinkage rates of the two materials. Since the high-shrinkage modified PA66 polymer is almost covered by the low-viscosity PA6, only the PA6 dyeing process conditions need to be considered in dyeing, and there will be no color difference due to the difference in performance between the two materials.

[0036] (3) The present invention is equipped with a special stretching processing device in the stretching stage. The pressure roller is the first gripping point for the fiber to enter the stretching stage. The hot plate is a guide plate with a heating wire inside to provide a constant temperature. The hot plate provides a constant temperature to eliminate the internal stress of the fiber and complete the shaping. The cold plate is the last guide plate for the fiber. The winding head completes the final shaping and winding of the fiber. This device can partially eliminate the internal stress of the POY fiber and reduce the adhesion between the silk layers, solving the problem of the difficulty in unwinding and stretching the two-component nylon POY fiber. At the same time, with the help of the hot plate shaping between the hot plate and the cold plate after stretching, the internal stress spiral structure formed by the fiber stretching is stabilized, so that the two-component nylon presents a straight wire state. At the same time, after the high-temperature processing of the hot plate, the balance of the internal stress of the fiber is destroyed, and the spiral three-dimensional curling structure formed is uniform, the fiber elasticity is good, and the finished fabric has excellent elasticity.

[0037] (4) Control of winding speed and network degree: the speed of the guide wire disc is overfeeding for fine denier and porous, and underfeeding for coarse denier and few holes to obtain nylon composite three-dimensional curled elastic fiber, which has low production cost and is easy to absorb color. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic structural diagram of the unwinding and drafting device of this application;

[0039] Figure 2a This is a photo of the finished silk obtained in Example 1;

[0040] Figure 2b This is a photo of the finished silk obtained in Example 2;

[0041] Figure 2c This is a photo of the finished silk obtained in Example 3;

[0042] Figure 3 This is a photo of ordinary nylon yarn.

[0043] Numbers in the figure: 1. POY yarn cake; 2. Tension regulator; 21. Tension rod; 3. Tension stabilizer; 31. Swing plate; 4. Press roller; 5. Hot plate; 6. Hot plate; 7. Cold plate; 8. Winding head. DETAILED DESCRIPTION

[0044] This embodiment explains the pre-humidity balancing process and the drawing process in detail.

[0045] Example 1

[0046] The method for preparing the bicomponent three-dimensional crimped nylon elastic fiber in this embodiment uses dried high-shrinkage modified PA66 polymer and low-viscosity PA6 as raw materials. The high-shrinkage modified PA66 polymer dry chips have a moisture content of 600±100ppm and a relative viscosity of 3.50; the low-viscosity PA6 dry chips have a moisture content of ≤200ppm and a relative viscosity of 2.45. The specific preparation steps are as follows:

[0047] (1) Extrusion melting: High shrinkage modified PA66 polymer dry chips enter the main screw extruder under nitrogen protection, melt, mix, and extrude to obtain the main spinning melt; low viscosity nylon 6 dry chips enter the sub-screw extruder under nitrogen protection, melt, mix, and extrude to obtain the sub-spinning melt.

[0048] Among them, the extrusion process of the main screw extruder is equipped with 5 heating zones, and the heating temperature of each zone is 285 / 290 / 295 / 300 / 305℃; the extrusion process of the auxiliary screw extruder is equipped with 5 heating zones, and the heating temperature of each zone is 285 / 280 / 275 / 270 / 265℃.

[0049] (2) Compounding: The main and auxiliary spinning melts enter the respective pipes and metering pumps in the main and auxiliary boxes, and finally enter the components in the main box. The main and auxiliary melts are eccentrically sheath-core composited and spun between the distribution plate and the spinneret of the component. The core layer is a high-shrinkage modified PA66 polymer, and the sheath layer is a low-viscosity PA6. The composite volume percentage of the two is 65:35, and the exposed central angle is 25°. Then, the nylon composite three-dimensional curly elastic POY is obtained by side-blowing cooling (20°C, 0.4m / sec), monomer suction and discharge, oiling (oil concentration 5%, oil nozzle elevation angle 10°), and POY molding and winding (conventional process).

[0050] (3) Pre-humidity balancing: Place the POY yarn cake 1 in a constant temperature and humidity environment for 8 hours. The temperature is 25°C and the humidity is 55%. This pre-humidity balancing eliminates some of the stress in the POY yarn, softens the yarn cake, and reduces adhesion between yarn layers.

[0051] (4) Drafting: Place the POY yarn cake 1 after pre-humidification and balancing treatment on the creel, and the corresponding drafting device is as follows: Figure 1As shown, the ambient temperature for drawing is 25°C and the humidity is 60%. The silk thread is led out from the creel through the tension regulator 2, and the silk thread passes through the angle spacing of the tension rod 21 to adjust the pre-tension to 0.2cN / dtex, and then passes through the tension stabilizer 3, and the swing plate 31 is selected according to 0.2g / dtex. Then it enters the pressure roller 4 and the hot plate 5. The temperature of the hot plate 5 is 60°C. The silk thread is drawn by the speed difference between the pressure roller 4 and the hot plate 5. In order to prevent the silk thread from slipping and the preheating effect of the hot plate 5 on the silk thread, the silk thread is wound around the pressure roller 4 for 1 circle and around the hot plate 5 for 8 circles, with a drawing ratio of 4 times. The drawn silk thread is shaped by the hot plate 6 between the hot plate 5 and the cold plate 7. The temperature of the hot plate 6 is 130°C, which stabilizes the silk thread drawing and forms an internal stress spiral structure (see Figure 2a shown).

[0052] (5) Winding: Winding speed 3000m / min, winding tension controlled at 6g, network pressure 0.25mpa.

[0053] No tube winding phenomenon occurred during the entire unwinding and drawing process; the resulting nylon composite yarn had a breaking elongation of 40.1%, a breaking strength of 2.58 cN / dtex, a boiling water shrinkage of 45.3%, a fiber crimp number of 35 / 50mm, a dyeing evenness ≥ level 4, an elastic recovery rate of 99.7%, and the finished composite yarn was a high-elastic nylon composite yarn.

[0054] Example 1-1

[0055] The configuration of this embodiment is the same as that of embodiment 1, except that in step (4), no tension adjustment unit is provided. The results are shown in Table 1.

[0056] There are three situations where the tension adjustment unit is not set:

[0057] A. No tension regulator is provided but a tension stabilizer is provided.

[0058] B. No tension stabilizer is set but tension regulator is set.

[0059] C. There is no tension regulator or tension stabilizer.

[0060] Table 1: Production status comparison table when no tension control unit is installed

[0061]

[0062]

[0063] The results in Table 1 show that compared with Example 1, when the tension adjustment unit is not provided, there will be uneven tension during the unwinding and stretching process, resulting in more serious tube winding during the unwinding process, and the structure of the obtained finished product will not change significantly.

[0064] Example 1-2

[0065] The configuration of this embodiment is the same as that of embodiment 1, except that in step (4), the pre-tensioning force is different. The specific configuration and results of the pre-tensioning force are shown in Table 2.

[0066] Table 2: Comparison of the effects of different pre-tensions

[0067]

[0068] Table 2 shows that pre-tension setting is related to unwinding and forming. When pre-tension is within the appropriate range, yarn unwinding is smooth, the finished product has a high fixed weight and length, and is of good quality. Conversely, when pre-tension is less than 0.05 cN / dtex (e.g., 0.02 cN / dtex in the table above) or greater than 0.2 cN / dtex (e.g., 0.3 cN / dtex in the table above), the fixed weight and length cannot be achieved, and the finished product grade is downgraded by 1-2 grades.

[0069] Examples 1-3

[0070] The configuration of this embodiment is the same as that of embodiment 1, except that in step (4), the stabilizing plate counterweight is different. The specific stabilizing plate counterweight configuration and results are shown in Table 2.

[0071] Table 3: Comparison of the effects of different tension stabilizer weights

[0072]

[0073] Table 3 shows that the tension stabilizer's counterweight setting is related to unwinding and forming. When the counterweight is within the appropriate range, the yarn unwinding is smooth, the finished product has a high standard weight and length, and good quality. Conversely, when the counterweight is less than 0.02g / dtex (e.g., 0.01g / dtex in the table above) or greater than 0.2g / dtex (e.g., 0.3g / dtex in the table above), the standard weight and length cannot be achieved, and the finished product grade is downgraded by 1-2 grades.

[0074] Examples 1-4

[0075] The configuration of this embodiment is the same as that of embodiment 1, except that in step (4), the number of turns is different. The specific number of turns on the pressure roller and the hot plate and the results are shown in Table 2.

[0076] Table 4: Comparison of the effects of different numbers of turns

[0077]

[0078] The results in Table 4 indicate that the primary function of pressure roller 4 during processing is to prevent fiber slippage. Therefore, the number of turns of pressure roller 4 should be kept relatively small (e.g., 3 or less, as shown in the table above). Heater plate 5, in addition to cooperating with pressure roller 4 to prevent fiber slippage, also preheats the fibers. Therefore, controlling its number of turns to a relatively high level (e.g., 6-8 turns) is more conducive to maintaining elastic recovery and achieving the spiral curvature of the structure. However, if the number of turns of heater plate 5 exceeds 8 (e.g., 10, as shown in the table above), the drafting and spinning-in operation will be affected due to the excessive number of turns.

[0079] Example 2

[0080] The method for preparing the bicomponent three-dimensional crimped nylon elastic fiber in this embodiment uses dried high-shrinkage modified PA66 polymer and low-viscosity PA6 as raw materials. The high-shrinkage modified PA66 polymer dry chips have a moisture content of 600±100ppm and a relative viscosity of 3.70; the low-viscosity PA6 dry chips have a moisture content of ≤200ppm and a relative viscosity of 2.45. The specific preparation steps are as follows:

[0081] (1) Extrusion melting: High shrinkage modified PA66 polymer dry chips enter the main screw extruder under nitrogen protection, melt, mix, and extrude to obtain the main spinning melt; low viscosity nylon 6 dry chips enter the sub-screw extruder under nitrogen protection, melt, mix, and extrude to obtain the sub-spinning melt.

[0082] Among them, the extrusion process of the main screw extruder is equipped with 5 heating zones, and the heating temperature of each zone is 285 / 290 / 295 / 300 / 305℃; the extrusion process of the auxiliary screw extruder is equipped with 5 heating zones, and the heating temperature of each zone is 285 / 280 / 275 / 270 / 265℃.

[0083] (2) Compounding: The main and auxiliary spinning melts enter the respective pipes and metering pumps in the main and auxiliary boxes, and finally enter the components in the main box. The main and auxiliary melts are eccentrically sheath-core composited and spun between the distribution plate and the spinneret of the component. The core layer is a high-shrinkage modified PA66 polymer, and the sheath layer is a low-viscosity PA6. The composite volume percentage of the two is 50:50, and the exposed central angle is 35°. Then, the nylon composite three-dimensional curly elastic POY is obtained by side-blowing cooling, monomer suction and discharge, oiling, and winding.

[0084] (3) Pre-humidity balancing: POY yarn cake 1 is placed in a constant temperature and humidity environment for 12 hours. The temperature is 22°C and the humidity is 60%. Pre-humidity balancing eliminates some of the stress in the POY yarn, softens the yarn cake, and reduces adhesion between yarn layers.

[0085] (4) Drawing: The POY yarn cake 1 after pre-humidification and balancing treatment is placed on the yarn frame. The ambient temperature of the drawing device is 20℃ and the humidity is 50%. The yarn is drawn out from the yarn frame through the tension regulator 2. The yarn passes through the angle spacing of the tension rod 21 and the pre-tension is adjusted to 0.05cN / dtex. Then it passes through the tension stabilizer 3 and the swing plate 31 and is matched according to 0.02g / dtex. Then it enters the pressure roller 4 and the hot plate 5. The temperature of the hot plate 5 is 55℃. The yarn is drawn by the speed difference between the pressure roller 4 and the hot plate 5. In order to prevent the yarn from slipping and the preheating effect of the hot plate 5 on the yarn, the yarn is wound 1 circle on the pressure roller 4 and 6 circles on the hot plate 5. The drawing ratio is 2.5 times. The drawn yarn is shaped by the hot plate 6 between the hot plate 5 and the cold plate 7. The temperature of the hot plate 6 is 100℃. The yarn is drawn stably to form an internal stress spiral structure (see Figure 2b shown).

[0086] (5) Winding: Winding speed 3000m / min, winding tension controlled at 6g, network pressure 0.25mpa.

[0087] No tube winding phenomenon occurred during the entire unwinding and drawing process; the resulting nylon composite yarn had a breaking elongation of 38.3%, a breaking strength of 3.21 cN / dtex, a boiling water shrinkage of 36.3%, a fiber crimp number of 30 / 50mm, a dyeing evenness ≥ level 4, and an elastic recovery rate of 99.1%, making it a highly elastic nylon composite yarn.

[0088] Example 3

[0089] The method for preparing the bicomponent three-dimensional crimped nylon elastic fiber in this embodiment uses dried high-shrinkage modified PA66 polymer and low-viscosity PA6 as raw materials. The high-shrinkage modified PA66 polymer dry chips have a moisture content of 600±100ppm and a relative viscosity of 3.60; the low-viscosity PA6 dry chips have a moisture content of ≤200ppm and a relative viscosity of 2.2. The specific preparation steps are as follows:

[0090] (1) Extrusion melting: High shrinkage modified PA66 polymer dry chips enter the main screw extruder under nitrogen protection, melt, mix, and extrude to obtain the main spinning melt; low viscosity nylon 6 dry chips enter the sub-screw extruder under nitrogen protection, melt, mix, and extrude to obtain the sub-spinning melt.

[0091] Among them, the extrusion process of the main screw extruder is equipped with 5 heating zones, and the heating temperature of each zone is 285 / 290 / 295 / 300 / 305℃; the extrusion process of the auxiliary screw extruder is equipped with 5 heating zones, and the heating temperature of each zone is 280 / 275 / 270 / 265 / 260℃.

[0092] (2) Compounding: The main and auxiliary spinning melts enter the respective pipes and metering pumps in the main and auxiliary boxes, and finally enter the components in the main box. The main and auxiliary melts are eccentrically sheath-core composited and spun between the distribution plate and the spinneret of the component. The core layer is a high-shrinkage modified PA66 polymer, and the sheath layer is a low-viscosity PA6. The composite volume percentage of the two is 50:50, and the exposed central angle is 40°. Then, the nylon composite three-dimensional curly elastic POY is obtained by side-blowing cooling, monomer suction and discharge, oiling, and winding.

[0093] (3) Pre-humidity balancing: POY yarn cake 1 is placed in a constant temperature and humidity environment for 24 hours. The temperature is 20°C and the humidity is 55%. Pre-humidity balancing eliminates some of the stress in the POY yarn, softens the yarn cake, and reduces adhesion between yarn layers.

[0094] (4) Drawing: Place the POY yarn cake 1 after pre-humidification and balancing treatment on the yarn frame. The ambient temperature of the drawing device is 25℃ and the humidity is 55%. The yarn is drawn out from the yarn frame through the tension regulator 2. The yarn passes through the angle spacing of the tension rod 21 and the pre-tension is adjusted to 0.15cN / dtex. Then it passes through the tension stabilizer 3 and the swing plate 31 and is matched according to 0.1g / dtex. Then it enters the pressure roller 4 and the hot plate 5. The temperature of the hot plate 5 is 55℃. The yarn is drawn by the speed difference between the pressure roller 4 and the hot plate 5. In order to prevent the yarn from slipping and the preheating effect of the hot plate 5 on the yarn, the yarn is wound 2 times on the pressure roller 4 and 8 times on the hot plate 5. The drawing ratio is 3 times. The drawn yarn is shaped by the hot plate 6 between the hot plate 5 and the cold plate 7. The temperature of the hot plate 6 is 110℃. The yarn drawing is stabilized to form an internal stress spiral structure (see Figure 2c shown).

[0095] (5) Winding: Winding speed 3000m / min, winding tension controlled at 6g, network pressure 0.25mpa.

[0096] No winding occurred during the unwinding and drawing process. The resulting nylon composite yarn had an elongation at break of 45.3%, a breaking strength of 2.52 cN / dtex, a boiling water shrinkage of 56.4%, a fiber crimp count of 37 per 50 mm, a dyeing uniformity of ≥ Grade 4, and an elastic recovery of 99.8%, demonstrating its high elasticity.

Claims

1. A method for preparing a nylon bicomponent self-crimping elastic fiber, characterized by: The modified PA66 polymer chips are used as raw materials, and the main spinning melt is obtained by drying, extruding and melting. The nylon 6 chips are used as raw materials, and the secondary spinning melt is obtained by drying, extruding and melting. The main and auxiliary spinning melts enter the channels in the main and auxiliary boxes respectively, and are metered into the spinning assembly according to a volume ratio of 50-65:50-35. The main and auxiliary melts are eccentrically combined and spun between the distribution plate and the spinneret of the spinning assembly. The pre-oriented yarn is then cooled by side blowing, the monomer is sucked and discharged, and oiled. The pre-oriented yarn is subjected to pre-humidification balance, drafting, hot plate setting, and winding to obtain the finished product of bicomponent nylon self-curling elastic fiber; The relative viscosity of the modified PA66 polymer chips is 3.5-3.7, and the relative viscosity of the nylon 6 chips is 2.2-2.45; In the eccentric sheath-core composite process, the main spinning melt is used as the core layer, the auxiliary spinning melt is used as the sheath layer, and the eccentric core layer is partially exposed, with an exposed central angle of 20 to 60 degrees; The pre-humidity balance refers to the pre-oriented yarn being conditioned for 8 to 24 hours in a constant temperature and humidity environment of 20 to 25°C and 50 to 60% humidity. The drafting process includes placing the pre-humidified and balanced POY on a creel, drawing out the POY and passing it through a tension regulator and a tension stabilizer in sequence. Under the conditions that the tension regulator pre-tensions 0.05-0.2 cN / dtex and the tension stabilizer counterweights 0.02-0.2 g / dtex, the POY then enters a pressure roller and a hot plate for drafting. The pre-oriented yarn is wound on the pressure roller for 2-3 turns, the hot plate temperature is 50-60°C, and the yarn is wound on the hot plate for 6-8 turns, with a draft ratio of 2-4. The finished product is then formed on a hot plate and wound by a winding head. The temperature of the hot plate is 100-130°C, the winding speed is 3000-4500m / min, the winding tension is controlled at 6-15g for fine denier and porous, ≥12g for coarse denier and few holes, and the network pressure is ≥0.2mpa.

2. The method for preparing a nylon bicomponent self-crimping elastic fiber according to claim 1, characterized in that: In the drying process of the modified PA66 polymer chips, the modified PA66 polymer chips are dried using dry air with a dew point temperature of ≤-50°C, the heating temperature is 70-100°C, and the heating time is 2-6 hours until the moisture content of the chips reaches 600±100ppm.

3. The method for preparing a nylon bicomponent self-crimping elastic fiber according to claim 1, characterized in that: In the drying process of PA6 chips, dry air with a dew point temperature of ≤-50℃ is used to dry the chips. The heating temperature is 80-110℃ and the heating time is 6-10h until the moisture content of the chips is ≤200ppm.

4. The method for preparing a nylon bicomponent self-crimping elastic fiber according to claim 1, characterized in that: In the oiling process, two oil nozzles are provided for oiling, and the elevation angle of the oil nozzles to the tow is 10-15 degrees.

5. The method for preparing a nylon bicomponent self-crimping elastic fiber according to claim 1, characterized in that: The side-blowing cooling temperature is 20-25°C, and the wind speed is 0.35-0.60m / sec.

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