High-resilience chinlon staple fiber and tensile test process thereof

Abstract

The invention discloses a high-resilience chinlon staple fiber and a tensile test process thereof, and belongs to the technical field of textile fiber processing. The high-resilience chinlon short fiber is characterized by comprising an inner core and a double-layer reverse spiral winding layer, and the double-layer reverse spiral winding layer is composed of an inner layer spiral and an outer layer spiral. The problems that existing chinlon short fibers are prone to permanent deformation after being stretched, the rebound resilience is poor, the tensile strength and the torsional strength are weak, and interface bonding is not firm are solved. By adopting the design of the inner core and the double-layer reverse spiral winding layer, the spiral of the inner layer and the spiral of the outer layer are respectively formed by the carbon nano tube reinforced blended elastomer, the composite structure not only improves the overall performance of the material, but also effectively disperses local stress, and through the processing steps of epoxy group silane coupling agent treatment, glutaraldehyde steam crosslinking and the like, the performance of the material is greatly improved. And the bonding force and the overall stability between the layers are further enhanced, and excellent dynamic rebound rate and torsional rigidity are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of textile fiber processing, and particularly to a high-elasticity polyamide staple fiber and its tensile test process. Background Technique

[0002] In the field of textile fiber processing, traditional polyamide staple fibers have certain limitations in achieving high elasticity and high tensile strength. Due to the inherent limitations of the single-layer structure, such materials are prone to delamination or permanent deformation due to stress concentration, affecting their durability and service life. Some existing technologies attempt to improve the rebound rate of polyamide staple fibers by adding elastomers, but this method usually cannot ensure sufficient torsional resistance at the same time, resulting in insufficient performance in some application scenarios.

[0003] Chinese Patent No. CN207244059U discloses a high-elasticity polyamide fiber, including a fiber body. The cross-section of the fiber body is circular, and a plum-blossom-shaped cavity for air circulation is provided inside the fiber body. A support part is provided in the cavity. The support part includes a central axis rod parallel to the length direction of the fiber body and several rebound rods extending from the central axis rod to the inner wall of the cavity. One end of the rebound rod is connected to the central axis rod, and the other end is connected to the inner wall of the cavity. When the fiber body is subjected to external force extrusion and collision, the cavity is compressed and reduced under the action of the external force, resulting in the bending or compression of the rebound rod. After absorbing the external force work, the unloading starts, the rebound rod starts to return to straight, and the fiber body returns to its original state.

[0004] However, in this patent, the rebound effect is achieved by the bending or compression of the rebound rod when subjected to external force and then returning to its original state. Long-term repeated stress may cause fatigue or even fracture of the rebound rod, affecting its durability and stability. At the same time, this patent mainly focuses on the rebound performance during extrusion and collision, and does not mention specific improvement measures for aspects such as tensile strength and torsional stiffness. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-elasticity polyamide staple fiber and its tensile test process. By adopting the design of an inner core plus a double-layer reverse spiral winding layer, the inner and outer layers of the spiral are respectively composed of a carbon nanotube-reinforced blend elastomer. This composite structure not only improves the overall performance of the material, but also effectively disperses local stress and reduces the possibility of stress concentration. In addition, through process steps such as treatment with epoxy-based silane coupling agent and cross-linking with glutaraldehyde vapor, the bonding force between layers and the overall stability are further enhanced, thereby achieving excellent dynamic rebound rate and torsional stiffness, and solving the problems raised in the above background technique.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A high-elasticity polyamide staple fiber, comprising a core and a double-layer reverse spiral winding layer, the double-layer reverse spiral winding layer being composed of an inner spiral and an outer spiral;

[0008] The core is made of highly oriented crystalline polyamide 6, adding 1.5%-2.5% graphene nanosheets, and after three-stage hot stretching, the crystallinity is ≥45%, and the tensile strength is ≥7.0 cN / dtex;

[0009] The inner spiral is composed of carbon nanotube-reinforced PA66, with a carbon nanotube content of 1%-2%, wound around the surface of the core in a counterclockwise direction, with a pitch of 30-50 μm and a diameter of 10-15 μm;

[0010] The outer spiral is composed of a TPEE and PA6 blend elastomer, with a TPEE proportion of 25%-35%, wound around the outside of the inner spiral in a clockwise direction, with a pitch of 50-80 μm and a diameter of 5-8 μm;

[0011] The surface of the core is treated with an epoxy-based silane coupling agent and etched with microgrooves to form chemical bonding and physical anchoring with the inner spiral.

[0012] Preferably, the microgrooves are laser-etched cross-network grooves, with a density of 50-80 lines / mm, a width of 1-3 μm, and a depth of 2 μm-4.5 μm.

[0013] Preferably, a polydopamine coating for enhancing environmental humidity responsiveness is added to the TPEE and PA6 blend elastomer of the outer spiral, with a coating content of 0.5%-1% and a thickness of 100-300 nm.

[0014] Preferably, the dynamic resilience rate of the staple fiber is ≥97%, and the torsional stiffness is ≥25 mN·mm / rad.

[0015] Preferably, the epoxy-based silane coupling agent contains an epoxy group (-O-CH2-CH(O)-CH2) and a silyl group (-Si-O-R), where:

[0016] The epoxy group undergoes a ring-opening reaction with the amino group (-NH2) of the core PA6 to form a covalent bond;

[0017] The silyl group generates silanol groups (-Si-OH) after hydrolysis and forms hydrogen bonds or condensation bonds with the polar groups (such as amide bonds) of the inner spiral PA66;

[0018] A molecular bridge is formed through covalent bonds and condensation bonds to chemically bond the core PA6 and the inner spiral PA66.

[0019] A tensile process for a high-elasticity polyamide staple fiber, used to realize a high-elasticity polyamide staple fiber, comprising the following steps:

[0020] Step 1: Ultrasonically mix graphene nanosheets with polyethylene glycol dispersion, melt-blend with PA6 chips, and prepare primary fibers by ultra-high speed spinning (5000 - 5500 m / min) at 270 - 275 °C. Then, perform first-stage stretching at 80 °C (stretching ratio 3×), second-stage stretching at 130 °C (stretching ratio 1.5×), and relaxation setting at 160 °C to obtain a highly oriented inner core;

[0021] Step 2: Use a microfluidic Y-shaped chip to control the flow rate ratio of PA66 / carbon nanotube melt to air at 1:3 and the pressure difference at 0.1 - 0.3 MPa to generate counterclockwise spiral fibers that wind around the inner core, and the PA66 / carbon nanotube melt is embedded in the microgrooves under high pressure;

[0022] Step 3: Deposit the blend solution of TPEE and PA6 by electrospinning (voltage 12 - 18 kV) as a clockwise spiral layer on a rotating receiver at a rotational speed of 7000 - 9000 rpm;

[0023] Step 4: Introduce glutaraldehyde vapor in an environment with humidity ≥ 85% to cause a cross-linking reaction between the outer and inner spiral layers. Set the reaction time to 10 - 20 minutes to form a synergistic high-rebound multi-layer structure.

[0024] Preferably, after the outer and inner spiral layers are cross-linked, hot press and roll setting are performed at 120 - 130 °C, and the pressure is set at 0.3 - 0.8 MPa to stabilize the spiral topological structure.

[0025] Preferably, the inner wall of the channel of the microfluidic Y-shaped chip has spiral guiding lines with a guiding angle of 15° - 30° and a channel accuracy of ≤ 5 μm.

[0026] Preferably, the electrospinning solution is a hexafluoroisopropanol solution of TPEE and PA6 with a mass concentration of 8% - 12%, and the solvent evaporation rate is controlled at 0.5 - 1.0 g / min.

[0027] Preferably, the spraying thickness of the epoxy group silane coupling agent is 0.5 - 1 μm to avoid embrittlement caused by local excess.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] 1. By adopting the design of a double-layer reverse spiral winding structure, the present invention mimics the biological tissue structure in nature, which helps to disperse stress and avoid damage caused by local stress concentration. The dynamic rebound rate of the staple fiber reaches ≥ 97%, ensuring that it can quickly return to its original state after being subjected to external forces.

[0030] 2. The core in the present invention is composed of highly oriented PA6 and graphene nanosheets are added. After three-stage hot stretching treatment, the tensile strength reaches or exceeds 7.0 cN / dtex, achieving effective enhancement. In addition, the inner-layer helix composed of carbon nanotube-reinforced PA66 and the outer-layer helix composed of TPEE / PA6 blend elastomer jointly endow the staple fiber with excellent torsional stiffness.

[0031] 3. In the present invention, cross-network microgrooves are formed on the surface of the core by laser etching and treated with epoxy-based silane coupling agent, enhancing chemical bonding and physical anchoring, effectively improving the bonding force between the layers inside the fiber, and enhancing the stability of the overall structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the overall structure and process of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0034] To solve the problems that existing nylon staple fibers are prone to permanent deformation after stretching, have poor resilience performance, weak tensile and torsional strength, and weak interfacial bonding, please refer to Figure 1 , the following technical solutions are provided in this embodiment:

[0035] A nylon staple fiber with high resilience includes a core and a double-layer reverse spiral winding layer, and the double-layer reverse spiral winding layer is composed of an inner-layer helix and an outer-layer helix.

[0036] The core is composed of highly oriented crystalline nylon 6, 1.5%-2.5% graphene nanosheets are added, and after three-stage hot stretching, the crystallinity ≥ 45%, and the tensile strength ≥ 7.0 cN / dtex;

[0037] Microgrooves are etched on the surface of the core, forming chemical bonding and physical anchoring with the inner-layer helix. The microgrooves are cross-network grooves formed by laser etching, with a density of 50-80 lines / mm, a width of 1-3 μm, and a depth of 2 μm-4.5 μm;

[0038] The surface of the inner core is treated with an epoxy silane coupling agent, which contains epoxy groups (-O-CH2-CH(O)-CH2) and silane groups (-Si-OR). The epoxy groups (-O-CH2-CH(O)-CH2) react with the amino groups (-NH2) of the inner core PA6 to form covalent bonds. The silane groups (-Si-OR) are hydrolyzed to form silanol groups (-Si-OH), which form hydrogen bonds or condensation bonds with the polar groups (such as amide bonds) of the inner spiral PA66. Molecular bridges are formed through covalent bonds and condensation bonds to chemically bond the inner core PA6 and the inner spiral PA66. The spray thickness of the epoxy silane coupling agent is 0.5-1μm to avoid embrittlement caused by local excess.

[0039] The inner spiral is composed of carbon nanotube-reinforced PA66, with a carbon nanotube content of 1%-2%, and is wound on the surface of the inner core in a counterclockwise direction, with a pitch of 30-50μm and a diameter of 10-15μm.

[0040] The outer spiral is composed of TPEE and PA6 blended elastomer, with TPEE accounting for 25%-35%, and is wound around the outside of the inner spiral in a clockwise direction, with a pitch of 50-80μm and a diameter of 5-8μm; a polydopamine coating is added to the TPEE and PA6 blended elastomer of the outer spiral to enhance the responsiveness to environmental humidity, with a coating content of 0.5%-1% and a thickness of 100-300nm.

[0041] This double-layer reverse spiral structure design mimics the structure of natural biological tissues, helping to disperse stress and avoid damage caused by local stress concentration.

[0042] In order to realize a high-elasticity nylon staple fiber, a tensile process of a high-elasticity nylon staple fiber is proposed, comprising the following steps:

[0043] Step 1: ultrasonically mix the graphene nanosheets with the polyethylene glycol dispersion, melt-blend with the PA6 slices, and obtain the primary fibers by high-speed spinning at 5000-5500 m / min at 270-275°C, and sequentially perform primary stretching at 80°C (stretching ratio 3×), secondary stretching at 130°C (stretching ratio 1.5×), and relaxation and shaping at 160°C to obtain a highly oriented inner core;

[0044] Step 2: using a microfluidic Y-type chip, the inner wall of the channel of the microfluidic Y-type chip has a spiral flow-guiding pattern, a flow-guiding angle of 15°-30°, a channel precision of ≤5μm, controlling the flow rate ratio of PA66 / carbon nanotube melt to air to 1:3, and an air pressure difference of 0.1-0.3MPa, generating counterclockwise spiral fibers and winding them around the inner core, and embedding the PA66 / carbon nanotube melt into the microgroove under high pressure;

[0045] Step 3: Electrospinning the blend solution of TPEE and PA6. The electrospinning solution is a hexafluoroisopropanol solution of TPEE and PA6 with a concentration of 8%-12%. The solvent evaporation rate is controlled at 0.5-1.0 g / min, the voltage is between 12-18 kV, and it is deposited as a clockwise spiral layer on a rotating receiver with a speed of 7000-9000 rpm.

[0046] Step 4: Introduce glutaraldehyde vapor in an environment with a humidity ≥85% to cause a crosslinking reaction between the outer helix and the inner helix. The reaction time is set to 10-20 minutes to form a synergistic high-elastic multi-layer structure. Finally, after crosslinking between the outer helix and the inner helix, hot rolling and shaping are carried out at 120-130°C with a pressure of 0.3-0.8 MPa to stabilize the spiral topological structure.

[0047] Now, according to the above tensile process of the high-elastic polyamide staple fiber, the polyamide staple fiber is prepared. By changing the material ratio and adjusting the process, the change in performance is shown. The specific embodiments are as follows:

[0048] Example 1:

[0049] Inner core preparation:

[0050] Material: PA6 base material chips are added with 2% graphene nanosheets, relative viscosity 2.9, water content ≤0.04%, thickness 3-5 nm. The graphene is dispersed by polyethylene glycol (PEG-4000) and then co-mixed by twin-screw.

[0051] Spinning: Melt at 270°C, spinning speed 5200 m / min, three-stage air cooling 25°C → 15°C → 5°C;

[0052] Drawing: Draw at 80°C for 3 times → draw at 130°C for 1.5 times → relax and shape at 160°C, crystallinity 47.0%.

[0053] Counterclockwise inner helix preparation:

[0054] Material: PA66 (DuPont Zytel 101) and 1.5% carboxylated carbon nanotubes (diameter 20 nm);

[0055] Process: Microfluidic Y-shaped chip, melt temperature 285°C, flow rate ratio 1:3, pressure difference 0.25 MPa, generating a counterclockwise spiral layer with a pitch of 40 μm and a diameter of 12 μm, and the melt is embedded in the microgrooves.

[0056] Clockwise outer helix preparation:

[0057] Material: TPEE (DSM Arnitel EL740) and PA6 with a mass ratio of 3:7;

[0058] Process: Electrospinning (voltage 15 kV, solution concentration 10% hexafluoroisopropanol), receiver rotation speed 8500 rpm, generating a clockwise spiral layer with a pitch of 60 μm and a diameter of 7 μm.

[0059] Interface treatment:

[0060] The surface of the inner core is etched with cross-grid grooves by laser, the groove depth is 3 μm, the density is 70 grooves / mm, and an epoxy-based silane coupling agent with a thickness of 0.8 μm is sprayed.

[0061] Steam crosslinking: Passing 5% glutaraldehyde vapor with a humidity of 90% for 15 minutes to crosslink the outer spiral and the inner spiral.

[0062] Hot pressing and shaping: At 125 °C and a pressure of 0.6 MPa, roll pressing and shaping.

[0063] Example 2:

[0064] Preparation of the inner core:

[0065] Materials: PA6 base material chips added with 2% graphene nanosheets, relative viscosity 2.9, water content ≤ 0.04%, thickness 3 - 5 nm, graphene is dispersed by polyethylene glycol (PEG - 4000) and then twin-screw blended.

[0066] Spinning: Melting at 269 °C, spinning speed 5200 m / min, three-stage air cooling 25 °C → 15 °C → 5 °C;

[0067] Stretching: Stretching at 80 °C by 3× → stretching at 130 °C by 1.5× → relaxation and shaping at 160 °C, crystallinity 47.3%.

[0068] Preparation of the counterclockwise inner spiral:

[0069] Materials: PA66 (DuPont Zytel 101) and 1.5% carboxylated carbon nanotubes (diameter 20 nm);

[0070] Process: Microfluidic Y-shaped chip, melt temperature 285 °C, flow rate ratio 1:3, pressure difference 0.25 MPa, in this example, the pitch of the inner spiral is adjusted to 30 μm, generating a counterclockwise spiral layer with a pitch of 30 μm and a diameter of 12 μm, and the melt is embedded in the microgrooves.

[0071] Preparation of the clockwise outer spiral:

[0072] Materials: TPEE (DSM Arnitel EL740) and PA6 with a mass ratio of 3:7;

[0073] Process: Electrospinning (voltage 15 kV, solution concentration 10% hexafluoroisopropanol), receiver rotation speed 8500 rpm, generating a clockwise spiral layer with a pitch of 60 μm and a diameter of 7 μm.

[0074] Example 3:

[0075] Preparation of the inner core:

[0076] Materials: In this example, the graphene content of the inner core is changed to 1.5%, 1.5% graphene nanosheets are added to the PA6 base material slices, the relative viscosity is 2.9, the water content is ≤0.04%, the thickness is 3 - 5 nm, and the graphene is dispersed by polyethylene glycol (PEG - 4000) and then melt - blended by a twin - screw extruder;

[0077] Spinning: Melt at 270°C, spinning speed 5200 m / min, three - stage air cooling at 25°C → 15°C → 5°C;

[0078] Drawing: Draw at 80°C for 3 times → draw at 130°C for 1.5 times → relax and shape at 160°C, crystallinity 47%.

[0079] Preparation of the counter - clockwise inner - layer helix:

[0080] Materials: PA66 (DuPont Zytel 101) and 1.5% carboxylated carbon nanotubes;

[0081] Process: Microfluidic Y - type chip, melt temperature 282°C, flow rate ratio 1:3, pressure difference 0.27 MPa, generating a counter - clockwise spiral layer with a pitch of 40 μm and a diameter of 12 μm, and the melt is embedded in the micro - grooves.

[0082] Preparation of the clockwise outer - layer helix:

[0083] Materials: TPEE (DSM Arnitel EL740) and PA6 with a mass ratio of 3:7;

[0084] Process: Electrospinning (voltage 15 kV, solution concentration 10% hexafluoroisopropanol), receiver rotation speed 8500 rpm, generating a clockwise spiral layer with a pitch of 60 μm and a diameter of 7 μm.

[0085] Interface treatment:

[0086] The surface of the inner core is etched with cross - grid grooves by laser, the groove depth is 3 μm, the density is 70 grooves / mm, and an epoxy - based silane coupling agent with a thickness of 0.8 μm is sprayed;

[0087] Steam cross - linking: Pass 5% glutaraldehyde vapor with a humidity of 89% for 15 minutes to cross - link the outer - layer helix and the inner - layer helix;

[0088] Hot - pressing and shaping: At 124°C and a pressure of 0.6 MPa, roll - press for shaping.

[0089] Comparative Example 1:

[0090] Preparation of the inner core:

[0091] Material: PA6 base material chips added with 2% graphene nanosheets, relative viscosity 2.9, water content ≤ 0.04%, thickness 3 - 5 nm, graphene dispersed by polyethylene glycol (PEG - 4000) and then twin - screw blended;

[0092] Spinning: Melt at 273 °C, spinning speed 5200 m / min, three - stage air cooling at 25 °C → 15 °C → 5 °C;

[0093] Drawing: Draw at 80 °C for 3 times → draw at 130 °C for 1.5 times → relax and shape at 160 °C, crystallinity 46%.

[0094] Counter - clockwise inner - layer helix preparation:

[0095] Material: PA66 (DuPont Zytel 101) and 1.5% carboxylated carbon nanotubes (diameter 20 nm);

[0096] Process: Microfluidic Y - type chip, melt temperature 285 °C, flow rate ratio 1:3, pressure difference 0.23 MPa, generate a counter - clockwise spiral layer with pitch 40 μm and diameter 12 μm, melt embedded in micro - grooves.

[0097] Clockwise outer - layer helix preparation:

[0098] Material: TPEE (DSM Arnitel EL740) and PA6 with a mass ratio of 3:7;

[0099] Process: Electrospinning (voltage 15 kV, solution concentration 10% hexafluoroisopropanol), receiver rotation speed 8500 rpm, generate a clockwise spiral layer with pitch 60 μm and diameter 7 μm.

[0100] Interface treatment:

[0101] In this comparative example, the micro - grooves on the surface of the inner core are cancelled, and the coupling agent between the inner core and the inner - layer helix is cancelled;

[0102] Steam cross - linking: Pass 5% glutaraldehyde vapor with humidity 90.4% for 15 minutes to cross - link the outer - layer helix and the inner - layer helix;

[0103] Hot - pressing and shaping: At 126 °C and 0.61 MPa pressure, roll - press for shaping.

[0104] Comparative example 2:

[0105] Inner - core preparation:

[0106] Material: PA6 base material chips added with 2% graphene nanosheets, relative viscosity 2.9, water content ≤ 0.04%, thickness 3 - 5 nm, graphene dispersed by polyethylene glycol (PEG - 4000) and then twin - screw blended;

[0107] Spinning: Melt at 275°C, spinning speed 5200 m / min, three-stage air cooling 25°C → 15°C → 5°C;

[0108] Drawing: Draw 3× at 80°C → draw 1.5× at 130°C → relaxation setting at 160°C, crystallinity 45.9%.

[0109] This comparative example cancels the preparation of the inner layer helix;

[0110] Clockwise outer layer helix preparation:

[0111] Materials: TPEE (DSM Arnitel EL 740) and PA6 with a mass ratio of 3:7;

[0112] Process: Electrospinning (voltage 15 kV, solution concentration 10% hexafluoroisopropanol), receiver rotation speed 8500 rpm, generating a clockwise spiral layer with a pitch of 60 μm and a diameter of 7 μm.

[0113] Interface treatment:

[0114] The surface of the inner core is etched with a cross-grid groove by laser, the groove depth is 3 μm, the density is 70 lines / mm, and an epoxy-based silane coupling agent with a thickness of 0.8 μm is sprayed;

[0115] Steam crosslinking: Pass 5% glutaraldehyde vapor, humidity 88.7% for 15 minutes to crosslink the outer layer helix and the inner layer helix;

[0116] Hot pressing and shaping: At 126.9°C, pressure 0.66 MPa, roll pressing and shaping.

[0117] Comparative example 3:

[0118] Inner core preparation:

[0119] Materials: PA6 base material slices are added with 2% graphene nanosheets, relative viscosity 2.9, water content ≤ 0.04%, thickness 3 - 5 nm, and graphene is dispersed by polyethylene glycol (PEG - 4000) and then twin-screw blended;

[0120] Spinning: Melt at 272°C, spinning speed 5200 m / min, three-stage air cooling 25°C → 15°C → 5°C;

[0121] Drawing: Draw 3× at 80°C → draw 1.5× at 130°C → relaxation setting at 160°C, crystallinity 47.7%.

[0122] Counterclockwise inner layer helix preparation:

[0123] Materials: PA66 (DuPont Zytel 101), and the inner layer helix of this comparative example does not add carbon nanotubes;

[0124] Process: Microfluidic Y-shaped chip, melt temperature 285°C, flow rate ratio 1:3, air pressure difference 0.26 MPa, generating a counterclockwise spiral layer with a pitch of 40 μm and a diameter of 12.1 μm, and the melt is embedded in the microgrooves.

[0125] Preparation of the clockwise outer spiral:

[0126] Materials: TPEE (DSM Arnitel EL740) and PA6 with a mass ratio of 3:7;

[0127] Process: Electrospinning (voltage 15 kV, solution concentration 10% hexafluoroisopropanol), receiver rotation speed 8500 rpm, generating a clockwise spiral layer with a pitch of 60 μm and a diameter of 7 μm.

[0128] Interface treatment:

[0129] The surface of the inner core is etched with cross-grid grooves by laser, the groove depth is 3 μm, the density is 70 lines / mm, and an epoxy-based silane coupling agent with a thickness of 0.8 μm is sprayed;

[0130] Steam crosslinking: Exposing to 5.1% glutaraldehyde vapor with a humidity of 88.7% for 15 minutes to crosslink the outer spiral and the inner spiral;

[0131] Thermal pressing and shaping: At 125.8°C and a pressure of 0.61 MPa, roll pressing for shaping.

[0132] It can be seen from the above examples and comparative examples that:

[0133] Compared with Example 1, in Example 2, the pitch of the inner spiral is adjusted from 40 μm to 30 μm;

[0134] Compared with Example 1, in Example 3, the graphene content in the inner core is adjusted from 2% to 1.5%;

[0135] In Comparative Example 1, the microgrooves on the surface of the inner core are removed, and the coupling agent between the inner core and the inner spiral is removed;

[0136] In Comparative Example 2, the preparation of the inner spiral is cancelled;

[0137] In Comparative Example 3, no carbon nanotubes are added to the inner spiral.

[0138] The polyamide staple fibers prepared in the above examples and comparative examples are tested as follows:

[0139] Rebound rate: Using an Instron 3365 dynamic fatigue testing machine, tensile strain 50%, frequency 1 Hz, 6000 cycles;

[0140] Tensile strength: Using a universal material testing machine, equipped with pneumatic clamps, combined with a laser diameter measuring instrument, tensile speed: 50 mm / min;

[0141] Torsional stiffness: Use a TA Instruments AR2000ex rheometer equipped with a torsional fixture. Fix both ends of the fiber, with a clamping distance of 20 mm. Apply a ±180° angular displacement at a rate of 10° / min, and record the torque-rotation curve.

[0142] Stiffness G = torque (mN·mm) / rotation angle (rad);

[0143] Interface peel strength: Use a micro-force testing machine to peel the inner helix from the inner core at a peeling rate of 1 mm / min, and take the average value of the stable stage for the force value.

[0144] The test data is shown in Table 1:

[0145] Table 1: Performance test results of each example and comparative example

[0146]

[0147] Based on the test results, the following conclusions are drawn:

[0148] The pitch spacing of the inner helix can significantly affect the torsional stiffness. As the spacing decreases, the torsional stiffness increases;

[0149] The carbon nanotube reinforcement of the inner helix contributes significantly to the tensile strength;

[0150] The bi-directional helical structure and interface bonding (micro-grooves + coupling agent) are the core to improve the resilience rate and torsional stiffness, and effectively maintain the firmness of the short fibers;

[0151] Among them, Example 1 is the optimal solution for comprehensive performance and can meet the requirements of high-end textiles.

[0152] Working principle: The inner core is composed of highly oriented crystalline polyamide 6 (PA6) mixed with 1.5% - 2.5% graphene nanosheets and undergoes three-stage hot stretching treatment to ensure a crystallinity of ≥45% and a tensile strength reaching or exceeding 7.0 cN / dtex. This process improves the basic mechanical properties of the fiber. The surface of the inner core is subjected to laser etching to form a cross-linked network of micro-grooves and is treated with an epoxy-based silane coupling agent to improve chemical bonding and physical anchoring. The epoxy group in the coupling agent reacts with the amino group of PA6 to form a covalent bond, while the silanol groups generated after hydrolysis of the silyl group form hydrogen bonds or condensation bonds with the inner helix PA66, enhancing the interlayer binding force. The inner helix uses carbon nanotube-reinforced PA66 and is wound around the outer surface of the inner core in a counterclockwise direction with a pitch of 30 - 50 μm and a diameter of 10 - 15 μm, increasing the rigidity and toughness of the structure.

[0153] The addition of carbon nanotubes not only improves the mechanical strength of the material, but also enhances other properties such as electrical conductivity. The outer layer helix is composed of a TPEE / PA6 blend elastomer and is wound around the outside of the inner layer helix in a clockwise direction with a pitch of 50 - 80 μm and a diameter of 5 - 8 μm. This double-layer reverse helix structure design mimics the structure of some biological tissues in nature, which helps to disperse stress and avoid damage caused by local stress concentration.

[0154] In an environment with a humidity ≥ 85%, glutaraldehyde vapor is introduced to cause a cross-linking reaction between the layers, further stabilizing the fiber structure. Then, hot pressing and rolling are carried out for shaping, with the pressure set between 0.3 - 0.8 MPa. Finally, high-performance polyamide staple fibers with a dynamic resilience rate ≥ 97% and a torsional stiffness ≥ 25 mN·mm / rad are obtained. This multi-level, composite construction method enables the staple fibers to have excellent tensile properties while maintaining high elasticity.

[0155] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.

[0156] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention.

Claims

1. A nylon staple fiber with high resilience, characterized in that: It includes an inner core and a double-layer reverse spiral winding layer, wherein the double-layer reverse spiral winding layer is composed of an inner spiral layer and an outer spiral layer; The inner core is made of highly oriented crystalline nylon 6, with 1.5%-2.5% graphene nanosheets added, and after three-stage thermal stretching, the crystallinity is ≥45%, and the tensile strength is ≥7.0cN / dtex; The inner spiral is composed of carbon nanotube-reinforced PA66, with a carbon nanotube content of 1%-2%, and is wound on the surface of the inner core in a counterclockwise direction, with a pitch of 30-50 μm and a diameter of 10-15 μm; The outer spiral is composed of TPEE and PA6 blended elastomer, with TPEE accounting for 25%-35%, and is wound around the outer side of the inner spiral in a clockwise direction, with a pitch of 50-80 μm and a diameter of 5-8 μm; The surface of the inner core is treated with an epoxy silane coupling agent and etched with micro grooves.

2. The high resilience nylon staple fiber according to claim 1, characterized in that: The micro grooves are laser-etched cross-network grooves with a density of 50-80 grooves / mm, a width of 1-3 μm, and a depth of 2 μm-4.5 μm.

3. The high resilience nylon staple fiber according to claim 2, characterized in that: A polydopamine coating for enhancing environmental humidity responsiveness is added to the TPEE and PA6 blended elastomer of the outer spiral, with a coating content of 0.5%-1% and a thickness of 100-300nm.

4. The high resilience nylon staple fiber according to claim 3, characterized in that: The dynamic resilience of the staple fibers is ≥97%, and the torsional rigidity is ≥25 mN·mm / rad.

5. The high resilience nylon staple fiber according to claim 4, characterized in that: The epoxysilane coupling agent contains epoxy groups and silane groups, wherein: The epoxy group undergoes a ring-opening reaction with the amino group of the inner core PA6 to form a covalent bond; After hydrolysis, the silane groups generate silanol groups, which form hydrogen bonds or condensation bonds with the polar groups of the inner helical PA66; The inner core PA6 is chemically bonded to the inner helix PA66 by forming a molecular bridge through covalent bonds and condensation bonds.

6. A tensile process for high resilience nylon staple fibers, used to produce the high resilience nylon staple fibers according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1: ultrasonically mix the graphene nanosheets with the polyethylene glycol dispersion, melt-blend with the PA6 slices, and obtain the primary fibers by ultra-high speed spinning at 270-275° C., and sequentially perform primary stretching at 80° C., secondary stretching at 130° C., and relaxation and shaping at 160° C. to obtain a highly oriented inner core; Step 2: Using a microfluidic Y-shaped chip, the flow rate ratio of PA66 / carbon nanotube melt to air is controlled to be 1:3, and the air pressure difference is 0.1-0.3MPa, so as to generate counterclockwise spiral fibers and wrap them around the inner core, and the PA66 / carbon nanotube melt is embedded in the microgrooves under high pressure; Step 3: The TPEE and PA6 blend solution is electrospun and deposited into a clockwise spiral layer on a rotating receiver with a rotation speed of 7000-9000 rpm; Step 4: Introduce glutaraldehyde vapor in an environment with a humidity of ≥85% to cause a cross-linking reaction between the outer spiral and the inner spiral. The reaction time is set to 10-20 minutes to form a synergistic high-resilience multi-layer structure.

7. The tensile process of high resilience nylon staple fiber according to claim 6, characterized in that: After the outer spiral and the inner spiral are cross-linked, they are subjected to hot pressing and rolling at 120-130° C. for shaping, with the pressure set at 0.3-0.8 MPa.

8. The tensile process of high resilience nylon staple fiber according to claim 7, characterized in that: The inner wall of the channel of the microfluidic Y-shaped chip has a spiral flow-guiding pattern, a flow-guiding angle of 15°-30°, and a channel precision of ≤5 μm.

9. The tensile process of high resilience nylon staple fiber according to claim 8, characterized in that: The electrospinning solution is a hexafluoroisopropanol solution of TPEE and PA6, with a mass concentration of 8%-12%, and a solvent volatility rate controlled at 0.5-1.0 g / min.

10. The tensile process of high resilience nylon staple fiber according to claim 9, characterized in that: The spraying thickness of the epoxy silane coupling agent is 0.5-1 μm.

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