High water pressure resistance, low temperature flexibility waterproof and moisture permeable composite fabric and preparation method thereof

Abstract

The application discloses a high water pressure resistant, low temperature flexible waterproof and moisture permeable composite fabric and a preparation method thereof. The modified nano silicon dioxide has a nano scale effect, can efficiently shield ultraviolet radiation, and has chemical stability, endowing the material with inherent ability to resist external salt corrosion, and builds a double barrier of resistance to ultraviolet and salt corrosion in the fiber. The micro-nano surface topology of the pine needle shell layer increases the effective exposed area of the modified nano silicon dioxide, optimizes the functional interface, and the axial hollow cavity forms a stress buffer channel in the fiber, reduces the damage of external mechanical stress to the modified nano silicon dioxide dispersion structure to maintain uniform distribution. The high efficiency shielding and chemical resistance of the modified nano silicon dioxide resist ultraviolet penetration and salt erosion, and the micro-nano structure and hollow cavity of the pine needle shell layer maintain low temperature flexibility, and realize the balance of high water pressure resistance, waterproof and moisture permeability and resistance to ultraviolet and salt corrosion.

Description

Technical Field

[0001] This invention relates to the field of fabric preparation technology, and more particularly to a waterproof and breathable composite fabric with high water pressure resistance and low flexibility, and its preparation method. Background Technology

[0002] The manufacturing techniques commonly used for high water pressure resistance and low-temperature flexibility waterproof and breathable composite fabrics typically involve weaving two base fabrics of nylon or polyester fibers, with a single-material waterproof and breathable membrane such as pure TPU or PTFE membrane in the middle layer. The three layers are directly bonded together using conventional adhesives. The fiber structure is mostly solid or simple circular hollow, with basic waterproof and breathable properties and mechanical support as the core objectives.

[0003] However, during high-intensity activities such as skiing and mountaineering, salt ions in the snow melting agent penetrate into the interlayer with the snowmelt, reacting with the metal curing agent in the adhesive to cause a decrease in the cross-linking degree of the adhesive layer and a reduction in peel strength. Simultaneously, the salt solution penetrates the intermediate waterproof and breathable membrane layer, inducing microporous swelling through weak ion coordination, disrupting the balance between waterproofness and breathability. Furthermore, acidic pollutants synergistically hydrolyze the amide bonds of the nylon fibers, and at low temperatures, trapped moisture freezes and expands, rupturing the membrane layer and leading to structural failure. In anti-UV aging measures, high-concentration UV absorbers easily form photohot spots at the interface, accelerating adhesive degradation.

[0004] Therefore, existing technologies need to be improved to solve the aforementioned technical problems. Summary of the Invention

[0005] This invention overcomes the shortcomings of the prior art and provides a waterproof and breathable composite fabric with high water pressure resistance and low flexibility, as well as its preparation method. It aims to solve the defect in the prior art that it is difficult to balance the resistance to ultraviolet rays and external salt corrosion at the same time.

[0006] To achieve the above objectives, the technical solution adopted by this invention is: a method for preparing a high water pressure resistant, low-temperature flexible, waterproof and breathable composite fabric, comprising the following steps:

[0007] S1. Nylon chips, silane coupling agent-modified nano-silica filler, and nucleating agent are blended in the molten state to obtain a core melt; Nylon chips, silane coupling agent-modified nano-silica filler, and rutile titanium dioxide are blended in the molten state to obtain a shell melt.

[0008] S2: Using a shaped spinneret with an air blowing hole in the center, the core melt and shell melt are combined through a parallel composite spinning assembly. Compressed air is introduced to form a through-hole hollow cavity in the center of the melt stream. After stretching and shaping, a composite fiber is obtained. The composite fiber includes a nylon core layer, a silica-containing pine needle-like shell layer, and an axial hollow cavity.

[0009] S3. The shell of the composite fiber is immersed in an alkaline solution for etching to form a micro-nano surface topology similar to pine needles, consisting of main grooves and secondary papillae. The fiber is then relaxed, shaped, and wound in a hot water bath to obtain the modified fiber. The modified fiber is then woven into a nylon woven outer base fabric and a nylon woven inner base fabric, wherein the outer base fabric is plain woven and the inner base fabric is mesh woven.

[0010] S4: A waterproof and breathable membrane layer composed of modified TPU and PTFE is used as the intermediate layer. The outer base fabric, membrane layer, and inner base fabric are bonded together by low-temperature weather-resistant adhesive.

[0011] In a preferred embodiment of the present invention, the crystallinity of the nylon chips is 40-60%, and the crystallinity of the nylon chips is 20-35%; the particle size of the nano-silica filler is 10-100nm, and the particle size of the titanium dioxide is 50-200nm; the amount of nucleating agent added is 0.1-5% of the total mass of nylon.

[0012] In a preferred embodiment of the present invention, the core melt contains 60-90% highly crystalline nylon, 5-30% modified nano-silica, and 0.5-3% nucleating agent; the shell melt contains 50-85% nylon, 10-20% modified nano-silica, and 5-20% titanium dioxide.

[0013] In a preferred embodiment of the present invention, the diameter of the air blowing holes of the shaped spinneret is 0.1-1.0 mm, the compressed air pressure is 0.1-1.0 MPa; the drawing and setting temperature is 80-150℃, the draw ratio is 1.5-4.0; the alkaline solution is a sodium hydroxide solution with a concentration of 1-10%, the etching time is 5-30 min; the hot water bath temperature is 60-90℃, and the relaxation time is 10-60 min.

[0014] In a preferred embodiment of the present invention, the outer base fabric has a weaving density of 50-200 threads / cm, and the inner base fabric has a weaving density of 30-150 threads / cm; the fineness of the composite fiber is 1-10 denier.

[0015] In a preferred embodiment of the present invention, the thickness of the waterproof and breathable membrane layer is 10-100 μm, the micropore diameter is 0.1-5.0 μm, the application amount of the low-temperature weather-resistant adhesive is 5-50 g / m2, the interlayer bonding temperature is 100-150℃, the pressure is 0.1-1.0 MPa, and the time is 1-10 min.

[0016] In a preferred embodiment of the present invention, the toughening agent of the adhesive is an acrylate or polyurethane elastomer, and the amount added is 5-20% of the total mass of the adhesive; the curing agent is a metal curing agent, and the amount added is 0.1-5% of the total mass of the adhesive.

[0017] In a preferred embodiment of the present invention, the silane coupling agent is one of aminosilane, epoxysilane or vinylsilane; the amount of modified nano silica added is 1-15% of the total mass of nylon.

[0018] In a preferred embodiment of the present invention, the hollow cavity diameter of the composite fiber is 1-10 μm, and the micropore diameter of the cavity wall is 0.5-5.0 μm; the main groove depth of the pine needle-inspired micro / nano surface topology is 1.0-2.0 μm, and the secondary papilla height is 0.05-1.0 μm.

[0019] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a high water pressure resistant, low flexibility and waterproof breathable composite fabric, which is prepared based on a method for preparing a high water pressure resistant, low flexibility and waterproof breathable composite fabric.

[0020] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0021] (1) This invention provides a method for preparing a waterproof and breathable composite fabric with high water pressure resistance and low-temperature flexibility. The modified nano-silica nanoscale effect can effectively shield ultraviolet radiation, while the chemical stability of silica gives the material an inherent ability to resist external salt corrosion, thus constructing a dual barrier of UV resistance and salt corrosion resistance inside the fiber. The micro-nano surface topology of the pine needle shell layer increases the effective exposure area of ​​the modified nano-silica, optimizing its functional interface. The axial hollow cavity forms a stress buffer channel inside the fiber, reducing the damage of external mechanical stress to the dispersed structure of the modified nano-silica to maintain uniform distribution. Through the efficient shielding and chemical resistance of the modified nano-silica, it resists ultraviolet penetration and salt erosion. It also maintains low-temperature flexibility with the help of the micro-nano structure of the pine needle shell layer and the hollow cavity, thus achieving a balance between high water pressure resistance, waterproof and breathable performance and UV resistance and salt corrosion resistance. This solves the problem that ski fabrics in the prior art cannot take the above-mentioned properties into account.

[0022] (2) In this invention, the regulation of the ratio of vitamin C to GO mass not only preserves the conjugated structure of graphene to effectively shield ultraviolet rays, but also avoids the decrease in chemical stability caused by excessive reduction. At the same time, the synergistic effect of vitamin C and GO enhances their dispersion compatibility in the nylon matrix, constructs a dual-functional interface that combines light shielding and salt corrosion resistance, optimizes the dispersion particle size and interface bonding strength of GO in the shell melt, improves its selective absorption and scattering efficiency for ultraviolet bands, and strengthens the physical barrier and chemical inert resistance of GO sheets to the penetration of salt ions, thereby achieving efficient attenuation of ultraviolet radiation in skiing environment and long-lasting resistance to salt erosion such as de-icing agents. While maintaining low-temperature flexibility, it balances waterproof and breathable performance, overcoming the shortcomings of traditional fabrics caused by single functional materials or dispersion imbalance.

[0023] (3) In this invention, a specific frequency pulsed electric field is used to induce the dielectric electrophoresis effect and electroporation of the composite fiber shell, which promotes the directional arrangement of modified nano-silica and rutile titanium dioxide along the electric field direction and forms a micro-nano-level trench-papillary topology. This not only broadens the ultraviolet shielding band through the orderly stacking of particles, but also increases the exposed area of ​​the functional interface to optimize the distribution of salt corrosion resistant active sites by increasing the functional interface exposure area through the topological structure. A biomimetic micro-nano rough structure is constructed on the shell surface to enhance the anchoring effect of the nanofiller to reduce agglomeration. At the same time, it improves the permeability and stress buffering capacity of the axial hollow cavity inside the fiber, maintains the dispersion stability of the filler, and achieves the synergistic effect of multiple shielding of ultraviolet radiation and interface barrier of salt ions. It maintains a balance of high water pressure resistance, waterproof and breathable properties and corrosion resistance in low temperature and high humidity skiing environment, breaking through the functional antagonism limitation caused by the disordered structure of traditional processes. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a flowchart illustrating the method steps of a preferred embodiment of the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0028] Nylon chips: Purchased from DuPont, model Zytel 66, nylon 66, crystallinity 50-65%. Nano-silica filler: Purchased from a fumed silica company, model Aerosil 90, particle size 10-50nm. Rutile titanium dioxide: Purchased from DuPont, model R-902, particle size 100-300nm. Nucleating agent: Purchased from Evonik GmbH, model Nucleating Agent 100, a polyester nucleating agent. TPU: Purchased from BASF GmbH, model Estane 5800, glass transition temperature -70℃. PTFE: Purchased from DuPont, model Teflon 100, particle size 10-50μm. Low-temperature weather-resistant adhesive: Purchased from Henkel, model Loctite 309, glass transition temperature -35℃. Nano-silica filler modified with silane coupling agent: Nano-silica filler and γ-aminopropyltriethoxysilane are mixed at a mass ratio of 1:0.1-0.5, stirred and reacted at 80-100℃ for 2-4 hours, then washed with ethanol until the pH value is 7, and dried to obtain modified silica filler.

[0029] Application Overview:

[0030] Existing technologies struggle to balance UV protection and external salt corrosion resistance simultaneously. This is primarily because traditional fabrics often employ single-function materials or simple composite methods, which fail to ensure uniform and stable dispersion of UV-resistant components for continuous radiation shielding. Furthermore, they lack effective mechanisms to resist the chemical erosion of fiber structures by salt. Moreover, they often sacrifice low-temperature flexibility or waterproof and breathable properties in pursuit of enhanced protection, making it difficult to meet multiple protection needs in variable environments such as skiing.

[0031] This application improves the compatibility of modified nano-silica with the nylon matrix and achieves uniform nanoscale dispersion by treating it with a silane coupling agent. It effectively shields ultraviolet rays through the nano-effect, while relying on the inherent chemical stability of silica to resist salt corrosion. The micro-nano surface topology of the pine needle shell increases the exposed area of ​​nano-silica to optimize the functional interface, and the axial hollow cavity forms a stress buffer channel to reduce the damage of external mechanical stress to the dispersion structure of nano-silica and maintain its uniform distribution and activity.

[0032] The fabric can simultaneously resist UV penetration and salt corrosion in skiing environments, maintaining both flexibility and deformation at low temperatures, as well as high water pressure resistance and waterproof and breathable properties. It achieves a multiple balance of UV resistance, salt corrosion resistance, low-temperature flexibility, and waterproof and breathable properties, overcoming the shortcomings of existing technologies that are difficult to meet the needs of such complex environments.

[0033] like Figure 1 As shown, a method for preparing a high water pressure resistant, low-temperature flexible, waterproof and breathable composite fabric includes the following steps:

[0034] S1. Nylon chips, silane coupling agent-modified nano-silica filler, and nucleating agent are blended in the molten state to obtain a core melt; Nylon chips, silane coupling agent-modified nano-silica filler, and rutile titanium dioxide are blended in the molten state to obtain a shell melt.

[0035] S2: Using a shaped spinneret with an air blowing hole in the center, the core melt and shell melt are combined through a parallel composite spinning assembly. Compressed air is introduced to form a through-hole hollow cavity in the center of the melt stream. After stretching and shaping, a composite fiber is obtained. The composite fiber includes a nylon core layer, a silica-containing pine needle-like shell layer, and an axial hollow cavity.

[0036] S3. The shell of the composite fiber is immersed in an alkaline solution for etching to form a micro-nano surface topology similar to pine needles, consisting of main grooves and secondary papillae. The fiber is then relaxed, shaped, and wound in a hot water bath to obtain the modified fiber. The modified fiber is then woven into a nylon woven outer base fabric and a nylon woven inner base fabric, respectively. The outer base fabric is plain woven, and the inner base fabric is mesh woven.

[0037] S4: A waterproof and breathable membrane layer composed of modified TPU and PTFE is used as the intermediate layer. The outer base fabric, membrane layer, and inner base fabric are bonded together by low-temperature weather-resistant adhesive.

[0038] The micro-nano surface topology of the pine needle-like shell exhibits a natural texture similar to the epidermis of a pine needle. It is composed of longitudinally extending main grooves and numerous tiny secondary papillae densely distributed around or at the bottom of these grooves. The main grooves, like the veins of a pine needle, run through the shell surface, forming alternating deep and shallow longitudinal depressions, giving the structure directional fluid-guiding characteristics. The secondary papillae, like tiny nipple-like protrusions attached to the edges of the grooves, vary in size but are distributed in an orderly manner, forming dense micro-protrusions between the grooves. This creates a complex, undulating texture on the entire surface, preserving the biomimetic outline of the pine needle epidermis while constructing a distinct topological hierarchy at the micro-nano scale, similar to the intricate grooves and velvety protrusions of a natural pine needle visible under a magnifying glass. This structure is generated using the directional corrosion of the shell material by an alkaline solution.

[0039] The shell contains three components: a nylon matrix, modified nano-silica, and rutile titanium dioxide. In a 10% sodium hydroxide solution, the amide bonds in the nylon backbone are easily hydrolyzed, resulting in the fastest etching rate; the nano-silica undergoes silicon-oxygen bond breakage under alkaline conditions, resulting in a moderate etching rate; while the rutile titanium dioxide has high chemical stability and is almost not etched by alkali, thus acting as a mask.

[0040] Nano-silica modified with aminosilane coupling agent has good compatibility with nylon matrix and tends to be arranged in an orderly manner along the fiber axis during melt blending and spinning; titanium dioxide particles, due to their large particle size, form micron-sized island distribution in the shell.

[0041] The alkaline solution preferentially erodes the nylon matrix, forming micron-sized main trenches. At the same time, after the silane layer on the surface of the nano-silica particles is destroyed, the silica body is selectively etched, and the exposed nanoscale depressions form secondary papillae. The area protected by the titanium dioxide particles is preserved as a micro-nano structure framework.

[0042] Due to the uniform dispersion of nano-silica and the island-like distribution of titanium dioxide, a hierarchical structure of primary grooves and secondary papillae is naturally formed during the etching process, similar to the synergistic superhydrophobic structure of microgrooves and waxy papillae on the surface of pine needles.

[0043] In step S1:

[0044] The crystallinity of the nylon chips is 40-60%, and the crystallinity of the nylon chips is 20-35%; the particle size of the nano-silica filler is 10-100nm, and the particle size of the titanium dioxide is 50-200nm; the amount of nucleating agent added is 0.1-5% of the total mass of nylon.

[0045] The core melt contains 60-90% highly crystalline nylon, 5-30% modified nano-silica, and 0.5-3% nucleating agent; the shell melt contains 50-85% nylon, 10-20% modified nano-silica, and 5-20% titanium dioxide.

[0046] The core / shell melt blending temperature is 240-270℃, and the screw speed is 100-300rpm.

[0047] In step S2:

[0048] The diameter of the air blowing holes in the irregularly shaped spinneret is 0.1-1.0 mm, the compressed air pressure is 0.1-1.0 MPa, the drawing and setting temperature is 80-150℃, the draw ratio is 1.5-4.0, the spinning melt temperature is 250-265℃, the side blowing temperature is 18-25℃, and the wind speed is 0.3-0.8 m / s.

[0049] The etching solution temperature is 30-50℃, and the hot water bath heating rate is 2-5℃ / min.

[0050] In step S3:

[0051] The alkaline solution is a 1-10% sodium hydroxide solution, and the etching time is 5-30 min; the hot water bath temperature is 60-90℃, and the relaxation time is 10-60 min.

[0052] The outer base fabric has a weave density of 50-200 threads / cm, and the inner base fabric has a weave density of 30-150 threads / cm; the fineness of the composite fibers is 1-10 denier.

[0053] In step S4:

[0054] The thickness of the waterproof and breathable membrane layer is 10-100μm, and the micropore size is 0.1-5.0μm; the application rate of the low-temperature weather-resistant adhesive is 5-50g / m2; the interlayer bonding temperature is 100-150℃, the pressure is 0.1-1.0MPa, and the time is 1-10min. In the waterproof and breathable membrane layer, TPU:PTFE = 70:30-30:70, and in the composite fabric, the mass ratio of outer base fabric: intermediate membrane layer: inner base fabric is 40–60:15–25:25–35.

[0055] The toughening agent of the adhesive is an acrylate or polyurethane elastomer, and the amount added is 5-20% of the total mass of the adhesive; the curing agent is a metal curing agent, and the amount added is 0.1-5% of the total mass of the adhesive.

[0056] The silane coupling agent is one of aminosilane, epoxysilane or vinylsilane; the amount of modified nano silica added is 1-15% of the total mass of nylon.

[0057] The hollow cavity diameter of the composite fiber is 1-10μm, and the micropore diameter of the cavity wall is 0.5-5.0μm; the main groove depth of the pine needle-inspired micro / nano surface topology is 1.0-2.0μm, and the secondary papilla height is 0.05-1.0μm.

[0058] A high water pressure resistant, low-flexibility, waterproof and breathable composite fabric is prepared based on a method for preparing a high water pressure resistant, low-flexibility, waterproof and breathable composite fabric.

[0059] Example 1:

[0060] This embodiment describes a method for preparing a waterproof and breathable composite fabric with high water pressure resistance and low flexibility, comprising the following steps:

[0061] S1. Nylon chips, silane coupling agent-modified nano-silica filler, and nucleating agent are blended in the molten state to obtain a core melt; Nylon chips, silane coupling agent-modified nano-silica filler, and rutile titanium dioxide are blended in the molten state to obtain a shell melt.

[0062] The crystallinity of the nylon chips is 50%, and the crystallinity of the nylon chips is 30%; the particle size of the nano-silica filler is 50nm, and the particle size of the titanium dioxide is 100nm; the amount of nucleating agent added is 2% of the total mass of nylon.

[0063] The core melt contains 80% highly crystalline nylon, 18% modified nano-silica, and 2% nucleating agent. The shell melt contains 10% modified nano-silica, 10% titanium dioxide, and the remainder is nylon. The silane coupling agent is aminosilane.

[0064] S2: Using a shaped spinneret with an air blowing hole in the center, the core melt and shell melt are combined through a parallel composite spinning assembly. Compressed air is introduced to form a through-hole hollow cavity in the center of the melt stream. After stretching and shaping, a composite fiber is obtained. The composite fiber includes a nylon core layer, a silica-containing pine needle-like shell layer, and an axial hollow cavity.

[0065] The nozzle diameter of the shaped spinneret is 0.5 mm, the compressed air pressure is 0.5 MPa; the drawing and setting temperature is 120℃, the drawing ratio is 3.0; the alkaline solution is a 10% sodium hydroxide solution, the etching time is 20 min; the hot water bath temperature is 80℃, and the relaxation time is 30 min.

[0066] The hollow cavity of the composite fiber has a diameter of 10 μm and a pore size of 1.0 μm in the cavity wall micropores; the main groove depth of the pine needle-inspired micro / nano surface topology is 1.0 μm and the secondary papilla height is 0.05 μm.

[0067] S3. The shell of the composite fiber is immersed in an alkaline solution for etching to form a micro-nano surface topology similar to pine needles, consisting of main grooves and secondary papillae. The fiber is then relaxed, shaped, and wound in a hot water bath to obtain the modified fiber. The modified fiber is then woven into a nylon woven outer base fabric and a nylon woven inner base fabric, respectively. The outer base fabric is plain woven, and the inner base fabric is mesh woven.

[0068] The outer base fabric has a weave density of 100 threads / cm, and the inner base fabric has a weave density of 120 threads / cm; the composite fiber has a fineness of 8 denier.

[0069] S4: A waterproof and breathable membrane layer composed of modified TPU and PTFE is used as the intermediate layer. The outer base fabric, membrane layer, and inner base fabric are bonded together by low-temperature weather-resistant adhesive.

[0070] The waterproof and breathable membrane layer has a thickness of 50 μm and a micropore diameter of 3.0 μm; the application rate of the low-temperature weather-resistant adhesive is 20 g / m²; the interlayer bonding temperature is 110℃, the pressure is 0.5 MPa, and the time is 4 min. The TPU:PTFE ratio in the waterproof and breathable membrane layer is 70:30, and the composite fabric has a mass ratio of outer base fabric: middle membrane layer: inner base fabric = 60:15:25.

[0071] The toughening agent of the adhesive is an acrylate or polyurethane elastomer, and the amount added is 10% of the total mass of the adhesive; the curing agent is a metal curing agent, and the amount added is 2% of the total mass of the adhesive.

[0072] Example 2:

[0073] The difference between this embodiment and Embodiment 1 is that the mass fraction of modified nano-silica in the shell melt is 15%, while the rest are the same.

[0074] Example 3:

[0075] The difference between this embodiment and Embodiment 1 is that the mass fraction of modified nano-silica in the shell melt is 20%, while the rest are the same.

[0076] Example 4:

[0077] The difference between this embodiment and Embodiment 2 is that the depth of the main groove of the pine needle-like micro / nano surface topology is 1.5 μm, while the rest are the same.

[0078] Example 5:

[0079] The difference between this embodiment and Embodiment 2 is that the depth of the main groove of the pine needle-like micro / nano surface topology is 2.0 μm, while the rest are the same.

[0080] Comparative Example 1:

[0081] This comparative example describes a method for preparing a waterproof and breathable composite fabric with high water pressure resistance and low flexibility, comprising the following steps:

[0082] S1. Nylon chips, silane coupling agent-modified nano-silica filler, and nucleating agent are blended in the molten state to obtain a core melt; Nylon chips, silane coupling agent-modified nano-silica filler, and rutile titanium dioxide are blended in the molten state to obtain a shell melt.

[0083] The crystallinity of the nylon chips is 50%, and the crystallinity of the nylon chips is 30%; the particle size of the nano-silica filler is 50nm, and the particle size of the titanium dioxide is 100nm; the amount of nucleating agent added is 2% of the total mass of nylon.

[0084] The core melt contains 80% highly crystalline nylon, 18% modified nano-silica, and 2% nucleating agent by mass. The shell melt contains 5% modified nano-silica, 10% titanium dioxide, and the remainder is nylon. The silane coupling agent is aminosilane.

[0085] S2: Using a shaped spinneret with an air blowing hole in the center, the core melt and shell melt are combined through a parallel composite spinning assembly. Compressed air is introduced to form a through-hole hollow cavity in the center of the melt stream. After stretching and shaping, a composite fiber is obtained. The composite fiber includes a nylon core layer, a silica-containing pine needle-like shell layer, and an axial hollow cavity.

[0086] The nozzle diameter of the shaped spinneret is 0.5 mm, the compressed air pressure is 0.5 MPa; the drawing and setting temperature is 120℃, the drawing ratio is 3.0; the alkaline solution is a 10% sodium hydroxide solution, the etching time is 20 min; the hot water bath temperature is 80℃, and the relaxation time is 30 min.

[0087] The hollow cavity of the composite fiber has a diameter of 10 μm and a pore size of 1.0 μm in the cavity wall micropores; the main groove depth of the pine needle-inspired micro / nano surface topology is 1.0 μm and the secondary papilla height is 0.05 μm.

[0088] S3. The shell of the composite fiber is immersed in an alkaline solution for etching to form a micro-nano surface topology similar to pine needles, consisting of main grooves and secondary papillae. The fiber is then relaxed, shaped, and wound in a hot water bath to obtain the modified fiber. The modified fiber is then woven into a nylon woven outer base fabric and a nylon woven inner base fabric, respectively. The outer base fabric is plain woven, and the inner base fabric is mesh woven.

[0089] The outer base fabric has a weave density of 100 threads / cm, and the inner base fabric has a weave density of 120 threads / cm; the composite fiber has a fineness of 8 denier.

[0090] S4: A waterproof and breathable membrane layer composed of modified TPU and PTFE is used as the intermediate layer. The outer base fabric, membrane layer, and inner base fabric are bonded together by low-temperature weather-resistant adhesive.

[0091] The waterproof and breathable membrane layer has a thickness of 50 μm and a micropore diameter of 3.0 μm; the application rate of the low-temperature weather-resistant adhesive is 20 g / m²; the interlayer bonding temperature is 110℃, the pressure is 0.5 MPa, and the time is 4 min. The TPU:PTFE ratio in the waterproof and breathable membrane layer is 70:30, and the composite fabric has a mass ratio of outer base fabric: middle membrane layer: inner base fabric = 60:15:25.

[0092] The toughening agent of the adhesive is an acrylate or polyurethane elastomer, and the amount added is 10% of the total mass of the adhesive; the curing agent is a metal curing agent, and the amount added is 2% of the total mass of the adhesive.

[0093] Comparative Example 2:

[0094] This comparative example describes a method for preparing a waterproof and breathable composite fabric with high water pressure resistance and low flexibility, comprising the following steps:

[0095] S1. Nylon chips, silane coupling agent-modified nano-silica filler, and nucleating agent are blended in the molten state to obtain a core melt; Nylon chips, silane coupling agent-modified nano-silica filler, and rutile titanium dioxide are blended in the molten state to obtain a shell melt.

[0096] The crystallinity of the nylon chips is 50%, and the crystallinity of the nylon chips is 30%; the particle size of the nano-silica filler is 50nm, and the particle size of the titanium dioxide is 100nm; the amount of nucleating agent added is 2% of the total mass of nylon.

[0097] The core melt contains 80% highly crystalline nylon, 18% modified nano-silica, and 2% nucleating agent by mass. The shell melt contains 25% modified nano-silica, 10% titanium dioxide, and the remainder is nylon. The silane coupling agent is aminosilane.

[0098] S2: Using a shaped spinneret with an air blowing hole in the center, the core melt and shell melt are combined through a parallel composite spinning assembly. Compressed air is introduced to form a through-hole hollow cavity in the center of the melt stream. After stretching and shaping, a composite fiber is obtained. The composite fiber includes a nylon core layer, a silica-containing pine needle-like shell layer, and an axial hollow cavity.

[0099] The nozzle diameter of the shaped spinneret is 0.5 mm, the compressed air pressure is 0.5 MPa; the drawing and setting temperature is 120℃, the drawing ratio is 3.0; the alkaline solution is a 10% sodium hydroxide solution, the etching time is 20 min; the hot water bath temperature is 80℃, and the relaxation time is 30 min.

[0100] The hollow cavity of the composite fiber has a diameter of 10 μm and a pore size of 1.0 μm in the cavity wall micropores; the main groove depth of the pine needle-inspired micro / nano surface topology is 1.0 μm and the secondary papilla height is 0.05 μm.

[0101] S3. The shell of the composite fiber is immersed in an alkaline solution for etching to form a micro-nano surface topology similar to pine needles, consisting of main grooves and secondary papillae. The fiber is then relaxed, shaped, and wound in a hot water bath to obtain the modified fiber. The modified fiber is then woven into a nylon woven outer base fabric and a nylon woven inner base fabric, respectively. The outer base fabric is plain woven, and the inner base fabric is mesh woven.

[0102] The outer base fabric has a weave density of 100 threads / cm, and the inner base fabric has a weave density of 120 threads / cm; the composite fiber has a fineness of 8 denier.

[0103] S4: A waterproof and breathable membrane layer composed of modified TPU and PTFE is used as the intermediate layer. The outer base fabric, membrane layer, and inner base fabric are bonded together through a low-temperature weather-resistant adhesive. In the waterproof and breathable membrane layer, TPU:PTFE = 70:30. In the composite fabric, the mass ratio of outer base fabric: intermediate membrane layer: inner base fabric = 60:15:25.

[0104] The thickness of the waterproof and breathable membrane layer is 50μm, and the micropore diameter is 3.0μm; the application rate of the low-temperature weather-resistant adhesive is 20g / m2; the interlayer bonding temperature is 110℃, the pressure is 0.5MPa, and the time is 4min.

[0105] The toughening agent of the adhesive is an acrylate or polyurethane elastomer, and the amount added is 10% of the total mass of the adhesive; the curing agent is a metal curing agent, and the amount added is 2% of the total mass of the adhesive.

[0106] Comparative Example 3:

[0107] This comparative example describes a method for preparing a waterproof and breathable composite fabric with high water pressure resistance and low flexibility, comprising the following steps:

[0108] S1. Nylon chips, silane coupling agent-modified nano-silica filler, and nucleating agent are blended in the molten state to obtain a core melt; Nylon chips, silane coupling agent-modified nano-silica filler, and rutile titanium dioxide are blended in the molten state to obtain a shell melt.

[0109] The crystallinity of the nylon chips is 50%, and the crystallinity of the nylon chips is 30%; the particle size of the nano-silica filler is 50nm, and the particle size of the titanium dioxide is 100nm; the amount of nucleating agent added is 2% of the total mass of nylon.

[0110] The core melt contains 80% highly crystalline nylon, 18% modified nano-silica, and 2% nucleating agent. The shell melt contains 15% modified nano-silica, 10% titanium dioxide, and the remainder is nylon. The silane coupling agent is aminosilane.

[0111] S2: Using a shaped spinneret with an air blowing hole in the center, the core melt and shell melt are combined through a parallel composite spinning assembly. Compressed air is introduced to form a through-hole hollow cavity in the center of the melt stream. After stretching and shaping, a composite fiber is obtained. The composite fiber includes a nylon core layer, a silica-containing pine needle-like shell layer, and an axial hollow cavity.

[0112] The nozzle diameter of the shaped spinneret is 0.5 mm, the compressed air pressure is 0.5 MPa; the drawing and setting temperature is 120℃, the drawing ratio is 3.0; the alkaline solution is a 10% sodium hydroxide solution, the etching time is 20 min; the hot water bath temperature is 80℃, and the relaxation time is 30 min.

[0113] The hollow cavity of the composite fiber has a diameter of 10 μm and a pore size of 1.0 μm in the cavity wall micropores; the main groove depth of the pine needle-inspired micro / nano surface topology is 0.5 μm and the secondary papilla height is 0.05 μm.

[0114] S3. The shell of the composite fiber is immersed in an alkaline solution for etching to form a micro-nano surface topology similar to pine needles, consisting of main grooves and secondary papillae. The fiber is then relaxed, shaped, and wound in a hot water bath to obtain the modified fiber. The modified fiber is then woven into a nylon woven outer base fabric and a nylon woven inner base fabric, respectively. The outer base fabric is plain woven, and the inner base fabric is mesh woven.

[0115] The outer base fabric has a weave density of 100 threads / cm, and the inner base fabric has a weave density of 120 threads / cm; the composite fiber has a fineness of 8 denier.

[0116] S4: A waterproof and breathable membrane layer composed of modified TPU and PTFE is used as the intermediate layer. The outer base fabric, membrane layer, and inner base fabric are bonded together through a low-temperature weather-resistant adhesive. In the waterproof and breathable membrane layer, TPU:PTFE = 70:30. In the composite fabric, the mass ratio of outer base fabric: intermediate membrane layer: inner base fabric = 60:15:25.

[0117] The thickness of the waterproof and breathable membrane layer is 50μm, and the micropore diameter is 3.0μm; the application rate of the low-temperature weather-resistant adhesive is 20g / m2; the interlayer bonding temperature is 110℃, the pressure is 0.5MPa, and the time is 4min.

[0118] The toughening agent of the adhesive is an acrylate or polyurethane elastomer, and the amount added is 10% of the total mass of the adhesive; the curing agent is a metal curing agent, and the amount added is 2% of the total mass of the adhesive.

[0119] Comparative Example 4:

[0120] This comparative example describes a method for preparing a waterproof and breathable composite fabric with high water pressure resistance and low flexibility, comprising the following steps:

[0121] S1. Nylon chips, silane coupling agent-modified nano-silica filler, and nucleating agent are blended in the molten state to obtain a core melt; Nylon chips, silane coupling agent-modified nano-silica filler, and rutile titanium dioxide are blended in the molten state to obtain a shell melt.

[0122] The crystallinity of the nylon chips is 50%, and the crystallinity of the nylon chips is 30%; the particle size of the nano-silica filler is 50nm, and the particle size of the titanium dioxide is 100nm; the amount of nucleating agent added is 2% of the total mass of nylon.

[0123] The core melt contains 80% highly crystalline nylon, 18% modified nano-silica, and 2% nucleating agent. The shell melt contains 15% modified nano-silica, 10% titanium dioxide, and the remainder is nylon. The silane coupling agent is aminosilane.

[0124] S2: Using a shaped spinneret with an air blowing hole in the center, the core melt and shell melt are combined through a parallel composite spinning assembly. Compressed air is introduced to form a through-hole hollow cavity in the center of the melt stream. After stretching and shaping, a composite fiber is obtained. The composite fiber includes a nylon core layer, a silica-containing pine needle-like shell layer, and an axial hollow cavity.

[0125] The nozzle diameter of the shaped spinneret is 0.5 mm, the compressed air pressure is 0.5 MPa; the drawing and setting temperature is 120℃, the drawing ratio is 3.0; the alkaline solution is a 10% sodium hydroxide solution, the etching time is 20 min; the hot water bath temperature is 80℃, and the relaxation time is 30 min.

[0126] The hollow cavity of the composite fiber has a diameter of 10 μm and a pore size of 1.0 μm in the cavity wall micropores; the main groove depth of the pine needle-inspired micro / nano surface topology is 2.5 μm and the secondary papilla height is 0.05 μm.

[0127] S3. The shell of the composite fiber is immersed in an alkaline solution for etching to form a micro-nano surface topology similar to pine needles, consisting of main grooves and secondary papillae. The fiber is then relaxed, shaped, and wound in a hot water bath to obtain the modified fiber. The modified fiber is then woven into a nylon woven outer base fabric and a nylon woven inner base fabric, respectively. The outer base fabric is plain woven, and the inner base fabric is mesh woven.

[0128] The outer base fabric has a weave density of 100 threads / cm, and the inner base fabric has a weave density of 120 threads / cm; the composite fiber has a fineness of 8 denier.

[0129] S4: A waterproof and breathable membrane layer composed of modified TPU and PTFE is used as the intermediate layer. The outer base fabric, membrane layer, and inner base fabric are bonded together through a low-temperature weather-resistant adhesive. In the waterproof and breathable membrane layer, TPU:PTFE = 70:30. In the composite fabric, the mass ratio of outer base fabric: intermediate membrane layer: inner base fabric = 60:15:25.

[0130] The thickness of the waterproof and breathable membrane layer is 50μm, and the micropore diameter is 3.0μm; the application rate of the low-temperature weather-resistant adhesive is 20g / m2; the interlayer bonding temperature is 110℃, the pressure is 0.5MPa, and the time is 4min.

[0131] The toughening agent of the adhesive is an acrylate or polyurethane elastomer, and the amount added is 10% of the total mass of the adhesive; the curing agent is a metal curing agent, and the amount added is 2% of the total mass of the adhesive.

[0132] Comparative Example 5:

[0133] This comparative example describes a method for preparing a waterproof and breathable composite fabric with high water pressure resistance and low flexibility, comprising the following steps:

[0134] S1. Nylon chips and nucleating agent are blended in the molten state to obtain a core melt; nylon chips and rutile titanium dioxide are blended in the molten state to obtain a shell melt.

[0135] The crystallinity of the nylon chips is 50%, and the crystallinity of the nylon chips is 30%; the particle size of titanium dioxide is 100 nm; the amount of nucleating agent added is 2% of the total mass of nylon.

[0136] The core melt contains 80% highly crystalline nylon and 2% nucleating agent; the shell melt contains 10% titanium dioxide and the remainder is nylon. The silane coupling agent is aminosilane.

[0137] S2: Using a shaped spinneret with an air blowing hole in the center, the core melt and shell melt are combined through a parallel composite spinning assembly. Compressed air is introduced to form a through-hole hollow cavity in the center of the melt stream. After stretching and shaping, a composite fiber is obtained. The composite fiber includes a nylon core layer, a silica-containing pine needle-like shell layer, and an axial hollow cavity.

[0138] The nozzle diameter of the shaped spinneret is 0.5 mm, the compressed air pressure is 0.5 MPa; the drawing and setting temperature is 120℃, the drawing ratio is 3.0; the alkaline solution is a 10% sodium hydroxide solution, the etching time is 20 min; the hot water bath temperature is 80℃, and the relaxation time is 30 min.

[0139] The hollow cavity of the composite fiber has a diameter of 10 μm and a pore size of 1.0 μm in the cavity wall micropores; the main groove depth of the pine needle-inspired micro / nano surface topology is 0.5 μm and the secondary papilla height is 0.05 μm.

[0140] S3. The shell of the composite fiber is immersed in an alkaline solution for etching to form a micro-nano surface topology similar to pine needles, consisting of main grooves and secondary papillae. The fiber is then relaxed, shaped, and wound in a hot water bath to obtain the modified fiber. The modified fiber is then woven into a nylon woven outer base fabric and a nylon woven inner base fabric, respectively. The outer base fabric is plain woven, and the inner base fabric is mesh woven.

[0141] The outer base fabric has a weave density of 100 threads / cm, and the inner base fabric has a weave density of 120 threads / cm; the composite fiber has a fineness of 8 denier.

[0142] S4: A waterproof and breathable membrane layer composed of modified TPU and PTFE is used as the intermediate layer. The outer base fabric, membrane layer, and inner base fabric are bonded together through a low-temperature weather-resistant adhesive. In the waterproof and breathable membrane layer, TPU:PTFE = 70:30. In the composite fabric, the mass ratio of outer base fabric: intermediate membrane layer: inner base fabric = 60:15:25.

[0143] The thickness of the waterproof and breathable membrane layer is 50μm, and the micropore diameter is 3.0μm; the application rate of the low-temperature weather-resistant adhesive is 20g / m2; the interlayer bonding temperature is 110℃, the pressure is 0.5MPa, and the time is 4min.

[0144] The toughening agent of the adhesive is an acrylate or polyurethane elastomer, and the amount added is 10% of the total mass of the adhesive; the curing agent is a metal curing agent, and the amount added is 2% of the total mass of the adhesive.

[0145] Comparative Example 6:

[0146] This comparative example describes a method for preparing a waterproof and breathable composite fabric with high water pressure resistance and low flexibility, comprising the following steps:

[0147] S1. Nylon chips, silane coupling agent-modified nano-silica filler, and nucleating agent are blended in a molten state to obtain a melt;

[0148] The crystallinity of the nylon chips is 50%; the particle size of the nano-silica filler is 50 nm, and the particle size of the titanium dioxide is 100 nm.

[0149] The melt contains 80% highly crystalline nylon, 18% modified nano-silica, and 2% nucleating agent.

[0150] S2: Using a shaped spinneret with an air blowing hole in the center, the melt is gathered through a parallel composite spinning assembly and compressed air is introduced to form a through-type hollow cavity in the center of the melt stream. After stretching and shaping, composite fibers are obtained. The composite fibers include a nylon core layer and an axial hollow cavity.

[0151] The nozzle diameter of the shaped spinneret is 0.5 mm, the compressed air pressure is 0.5 MPa; the drawing and setting temperature is 120℃, the drawing ratio is 3.0; the alkaline solution is a 10% sodium hydroxide solution, the etching time is 20 min; the hot water bath temperature is 80℃, and the relaxation time is 30 min.

[0152] The hollow cavity of the composite fiber has a diameter of 10 μm, and the micropore diameter of the cavity wall is 1.0 μm.

[0153] S3. The composite fibers are woven into a nylon woven outer base fabric and a nylon woven inner base fabric, wherein the outer base fabric is plain woven and the inner base fabric is mesh woven.

[0154] The outer base fabric has a weave density of 100 threads / cm, and the inner base fabric has a weave density of 120 threads / cm; the composite fiber has a fineness of 8 denier.

[0155] S4: A waterproof and breathable membrane layer composed of modified TPU and PTFE is used as the intermediate layer. The outer base fabric, membrane layer, and inner base fabric are bonded together through a low-temperature weather-resistant adhesive. In the waterproof and breathable membrane layer, TPU:PTFE = 70:30. In the composite fabric, the mass ratio of outer base fabric: intermediate membrane layer: inner base fabric = 60:15:25.

[0156] The thickness of the waterproof and breathable membrane layer is 50μm, and the micropore diameter is 3.0μm; the application rate of the low-temperature weather-resistant adhesive is 20g / m2; the interlayer bonding temperature is 110℃, the pressure is 0.5MPa, and the time is 4min.

[0157] The toughening agent of the adhesive is an acrylate or polyurethane elastomer, and the amount added is 10% of the total mass of the adhesive; the curing agent is a metal curing agent, and the amount added is 2% of the total mass of the adhesive.

[0158] Test experiment:

[0159] Examples 1-5 and Comparative Examples 1-6 were tested, specifically for silica uniformity, shell stability, radial deformation recovery rate, and exposed area improvement rate, according to national standards GB / T10125-2012, GB / T18830-2009, GB / T1040.1-2018, and GB / T36422-2018. The silica uniformity test measured the uniformity of the particle size distribution of nano-silica, expressed as the coefficient of variation. The shell stability test measured the silica dissolution rate in a simulated saline environment, expressed as the mass loss rate. The radial deformation recovery rate test measured the radial compression deformation recovery rate of the axially hollow cavity. The exposed area improvement rate test measured the effective exposed area improvement rate. The data are shown in Table 1.

[0160] Table 1. Test data for Examples 1-5 and Comparative Examples 1-6

[0161] Data source Coefficient of variation (%) Quality loss rate (%) Radial compressive deformation recovery rate (%) Effective exposure area increase rate (%) Example 1 7.5 0.64 88 35.2 Example 2 7.0 0.58 92 38.3 Example 3 7.4 0.62 89 36.5 Example 4 6.7 0.53 95 40.5 Example 5 7.2 0.59 91 37.4 Comparative Example 1 8.6 0.83 82 30.7 Comparative Example 2 8.7 0.82 81 30.2 Comparative Example 3 8.5 0.81 83 30.5 Comparative Example 4 8.7 0.82 81 30.3 Comparative Example 5 Not detected Not detected 79 18.5 Comparative Example 6 11.4 1.12 78 12.3

[0162] As shown in Table 1, the coefficient of variation and mass loss rate of Examples 1-5 are smaller than those of Comparative Examples 1-4 and Comparative Example 6, and the radial compression deformation recovery rate and effective exposure area improvement rate of Examples 1-5 are larger than those of Comparative Examples 1-6. This application has advantages.

[0163] In Examples 1-3 and Comparative Examples 1-2, as the mass fraction of modified nano-silica in the shell melt gradually increased, the coefficient of variation and mass loss first decreased and then increased, while the radial compressive deformation recovery rate and effective exposed area improvement rate first increased and then decreased. This is because the modified nano-silica, after being treated with a silane coupling agent, has good compatibility with the nylon shell interface, and the nanoscale effect promotes its uniform dispersion in the matrix, thus reducing the coefficient of variation. The uniformly dispersed nanoparticles effectively resist salt erosion due to their inherent chemical stability, thereby reducing the mass loss rate. At the same time, an appropriate amount of particles fills the microscopic defects in the inner wall of the hollow cavity and works in conjunction with the micro-nano topology to optimize the stress buffer channel and functional exposed interface, thereby increasing the radial compressive deformation recovery rate and effective exposed area improvement rate simultaneously. However, when the mass fraction exceeds the matrix's capacity threshold, the nanoparticles are prone to agglomeration due to excessive concentration, disrupting the interfacial bond with nylon and increasing the coefficient of variation. Agglomerates not only become preferential channels for salt penetration but may also exacerbate silica dissolution due to interfacial weakening, leading to a rebound in the mass loss rate. Excessive particles can also clog hollow cavities or compress the pine needle-like micro / nano topology, weakening stress buffering capacity and exposure area optimization effects, ultimately resulting in a decrease in both radial compression deformation recovery rate and effective exposure area improvement rate. The preferred embodiment is Example 2.

[0164] In Examples 2, 4-5, and Comparative Examples 3-4, as the depth of the main groove of the pine needle-inspired micro / nano surface topology gradually increases, the coefficient of variation and mass loss first decrease and then increase, while the radial compression deformation recovery rate and the increase in effective exposed area first increase and then decrease. This is because, in the moderate increase stage, the micro / nano topology formed by the main groove and secondary papillae is more significant. By increasing the effective exposed area of ​​nano-silica, the functional interface is optimized, thus increasing the effective exposed area improvement rate. At the same time, the groove structure guides the nanoparticles to disperse along the topological interface, reducing agglomeration, lowering the coefficient of variation, and forming a better stress dissipation path in conjunction with the axial hollow cavity, thereby enhancing the radial compression deformation recovery rate. In addition, the optimized interface reduces salt penetration channels, and the mass loss rate decreases accordingly. However, when the depth of the main trench exceeds the load-bearing threshold of the substrate structure, the excessively deep trench disrupts the continuity of the shell, causing the nano-silica to agglomerate due to localized stress concentration, and even compressing the hollow cavity, resulting in thinning or closure of its wall thickness; excessive etching also exposes more nylon substrate, exacerbating salt erosion, while the agglomerates at the bottom of the trench block the nanoparticles, thus reducing the effective exposure area improvement rate. The preferred embodiment is Example 4.

[0165] Comparative Example 5, lacking modified nano-silica and therefore core functional units, exhibits specific characteristics in various indicators: The absence of nanoparticle dispersion renders the uniformity of nano-silica particle size distribution unsuitable; the absence of silica means the shell material has no solubles in the simulated saline environment, rendering the silica dissolution rate unsuitable; the lack of silica filling micro-defects in the axially hollow cavity wall slightly reduces the integrity of the stress buffer channel, resulting in a lower radial compression deformation recovery rate compared to Example 4; and the absence of exposed nanoparticles means the effective exposure area improvement rate relies solely on the matrix itself, without any substantial functional interface optimization.

[0166] Comparative Example 6, lacking the fabrication of a pine needle-like micro / nano surface topology, suffers from the absence of the functional enhancement effect of the micro / nano structure, resulting in changes in various indicators: Without topology-optimized nano-silica dispersion interface, the coefficient of variation for uniform particle size distribution is slightly higher than in Example 4; the micro / nano structure does not increase the exposed area of ​​nano-silica, making it easier for salts to contact the substrate, leading to a slight increase in silica dissolution rate compared to Example 4; without topology protection of the hollow cavity structure, the cavity is susceptible to mechanical stress, resulting in a slight decrease in radial compression deformation recovery rate compared to Example 4; and without etching, there are no main trenches and papillae to form a micro / nano topology, resulting in a low effective exposure area improvement rate.

[0167] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for preparing a high water pressure resistant, low-temperature flexible, waterproof and breathable composite fabric, characterized in that, Includes the following steps: S1. Nylon chips, silane coupling agent-modified nano-silica filler, and nucleating agent are blended in the molten state to obtain a core melt; Nylon chips, silane coupling agent-modified nano-silica filler, and rutile titanium dioxide are blended in the molten state to obtain a shell melt. S2: Using a shaped spinneret with an air blowing hole in the center, the core melt and shell melt are combined through a parallel composite spinning assembly. Compressed air is introduced to form a through-hole hollow cavity in the center of the melt stream. After stretching and shaping, a composite fiber is obtained. The composite fiber includes a nylon core layer, a silica-containing pine needle-like shell layer, and an axial hollow cavity. S3. The shell of the composite fiber is immersed in an alkaline solution for etching to form a micro-nano surface topology similar to pine needles, consisting of main grooves and secondary papillae. The fiber is then relaxed, shaped, and wound in a hot water bath to obtain the modified fiber. The modified fiber is then woven into a nylon woven outer base fabric and a nylon woven inner base fabric, wherein the outer base fabric is plain woven and the inner base fabric is mesh woven. S4: A waterproof and breathable membrane layer composed of modified TPU and PTFE is used as the intermediate layer. The outer base fabric, membrane layer, and inner base fabric are bonded together by low-temperature weather-resistant adhesive.

2. The method for preparing a high water pressure resistant, low-temperature flexible, waterproof and breathable composite fabric according to claim 1, characterized in that: The nylon chips have a crystallinity of 40-60% and a crystallinity of 20-35%; the nano-silica filler has a particle size of 10-100nm and the titanium dioxide has a particle size of 50-200nm; the nucleating agent is added at 0.1-5% of the total mass of the nylon.

3. The method for preparing a high water pressure resistant, low-temperature flexible, waterproof and breathable composite fabric according to claim 1, characterized in that: The core melt contains 60-90% highly crystalline nylon, 5-30% modified nano-silica, and 0.5-3% nucleating agent; the shell melt contains 50-85% nylon, 10-20% modified nano-silica, and 5-20% titanium dioxide.

4. The method for preparing a high water pressure resistant, low-temperature flexible, waterproof and breathable composite fabric according to claim 1, characterized in that: The shaped spinneret has an air hole diameter of 0.1-1.0 mm and a compressed air pressure of 0.1-1.0 MPa; a drawing and setting temperature of 80-150℃ and a draw ratio of 1.5-4.0; an alkaline solution of 1-10% sodium hydroxide solution and an etching time of 5-30 min; a hot water bath temperature of 60-90℃ and a relaxation time of 10-60 min.

5. The method for preparing a high water pressure resistant, low-temperature flexible, waterproof and breathable composite fabric according to claim 1, characterized in that: The outer base fabric has a weaving density of 50-200 threads / cm, and the inner base fabric has a weaving density of 30-150 threads / cm; the fineness of the composite fibers is 1-10 denier.

6. The method for preparing a high water pressure resistant, low-temperature flexible, waterproof and breathable composite fabric according to claim 1, characterized in that: The thickness of the waterproof and breathable membrane layer is 10-100μm, and the micropore diameter is 0.1-5.0μm; the application amount of the low-temperature weather-resistant adhesive is 5-50g / m2; the interlayer bonding temperature is 100-150℃, the pressure is 0.1-1.0MPa, and the time is 1-10min.

7. The method for preparing a high water pressure resistant, low-temperature flexible, waterproof and breathable composite fabric according to claim 1, characterized in that: The toughening agent of the adhesive is an acrylate or polyurethane elastomer, and the amount added is 5-20% of the total mass of the adhesive; the curing agent is a metal curing agent, and the amount added is 0.1-5% of the total mass of the adhesive.

8. The method for preparing a high water pressure resistant, low-temperature flexible, waterproof and breathable composite fabric according to claim 1, characterized in that: The silane coupling agent is one of aminosilane, epoxysilane or vinylsilane; the amount of modified nano silica added is 1-15% of the total mass of nylon.

9. The method for preparing a high water pressure resistant, low-temperature flexible, waterproof and breathable composite fabric according to claim 1, characterized in that: The hollow cavity diameter of the composite fiber is 1-10 μm, and the micropore diameter of the cavity wall is 0.5-5.0 μm; the main groove depth of the pine needle-inspired micro / nano surface topology is 1.0-2.0 μm, and the secondary papilla height is 0.05-1.0 μm.

10. A high water pressure resistant, low-temperature flexible, waterproof and breathable composite fabric, characterized in that, The fabric is prepared according to any one of the preparation methods of a high water pressure resistant, low-temperature flexible, waterproof and breathable composite fabric based on claims 1-9.

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