Nano-powder filled anti-needling composite material and preparation method thereof

Abstract

The invention discloses a nanopowder-filled anti-needling composite material and a preparation method thereof. The preparation method comprises the following steps: S1, putting a fabric into a soaking solution in which filling particles are uniformly dispersed; the viscosity of the soaking solution dispersed with the filling particles is 18-32 mPa.s; the nanometer filling particles comprise one or more of calcium carbonate powder, talcum powder and superfine siliceous lime; s2, dynamically soaking the fabric in a soaking solution in which filling particles are dispersed, and filling nano filling particles in the middle of fibers of the fabric through presoaking, stretching, filling, adsorbing and cooling and locking; s3, drying; and S4, high-temperature forming and gradient cooling are conducted, and the target anti-needling composite material is obtained. According to the invention, particle modification-system regulation and control-process cooperation is provided to controllably fill, distribute and fix the nano filling particles in the fiber gaps, the distribution and combination state of the particles in the fiber gaps is accurately regulated and controlled, the process is simple, the cost is controllable, and the anti-needling performance and the wearing comfort are both considered.

Description

Technical Field

[0001] This invention relates to the field of protective materials technology, and in particular to a powder-filled anti-needle-puncture composite material and its preparation method. Background Technology

[0002] Among existing protective materials, pure PE fibers, especially ultra-high molecular weight PE fibers, or other high-density and high-toughness fibers such as high-density polyester and nylon, and knitted fabrics are widely used in the field of protection due to their advantages such as lightness, breathability, and abrasion resistance. However, unmodified fabrics have poor needle-punch resistance. The American standard ASTM F2878 needle-punch test can only reach level zero, with a puncture force of less than 20N, which cannot resist the puncture of conventional sharp objects and is difficult to meet the protection needs of high-risk scenarios such as machining, construction, medical operations, and outdoor work.

[0003] Current mainstream solutions for improving the needle-punch resistance of fabrics have some obvious drawbacks. For example, increasing the thickness and using multi-layer composites: improving protection by stacking fabric layers or composite metal mesh and rigid plates results in products that are bulky when the thickness exceeds 5mm, with an air permeability of ≤5mm / s, significantly reduced breathability, poor wearing comfort, fatigue from prolonged wear, and restricted movement. Using special fibers such as aramid and carbon fiber for direct weaving is expensive, with raw material prices 3-5 times that of ordinary PE fibers, resulting in high production costs and making large-scale adoption difficult, and the fabric lacks flexibility. Coating the fabric surface with resin, rubber, or other coatings can improve the needle-punch resistance level to 1-2, but the coating has weak bonding with the fibers, making it prone to cracking and peeling, resulting in a short service life, a wear resistance of less than 3000 cycles, loss of fabric flexibility, and a breaking elongation of less than 10%, leading to a poor wearing experience.

[0004] CN102116595A improves stab resistance by simply soaking nonwoven fabric in adhesive and then laminating it with an adhesive, and the reliance on multi-layer lamination results in a heavy fabric, which still makes it difficult to overcome the aforementioned problems in the prior art. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a powder-filled anti-needle-puncture composite material. This invention proposes a "particle modification-system regulation-process synergy" method to controllably fill and fix nano-filler particles in the fiber gaps, precisely control the distribution and binding state of the particles in the fiber gaps, and achieve a simple process, controllable cost, and a balance between anti-needle-puncture performance and wearability comfort.

[0006] To solve this technical problem, the technical solution of the present invention is: a method for preparing a powder-filled anti-needle-puncture composite material, comprising the following steps: S1. Immerse the fabric in an soaking solution in which filling particles are evenly dispersed. The viscosity of the resulting soaking solution containing the dispersed filler particles was 18-32 mPa·s; The nanofiller particles include one or more of calcium carbonate powder, talc powder, and ultrafine silica lime. S2. The fabric is dynamically soaked in an immersion solution containing dispersed filling particles. Through pre-soaking, stretching, filling, adsorption, cooling and locking, the nano filling particles fill the middle of the fabric fibers. S3, Drying; S4, high-temperature molding and gradient cooling, yield the target needle-punch resistant composite material.

[0007] The preferred step S3 drying includes the following steps: S31. Take out the soaked fabric and remove excess soaking liquid from the surface by squeezing rollers to control the liquid content of the fabric to 30-40% (by weight). Dry the fabric in an oven at 60-80℃ for 1-2 hours, then transfer it to a vacuum freeze dryer at -40 to -50℃ and a vacuum degree of -0.08 to -0.1MPa for 8-12 hours. The final fabric moisture content is ≤5% (measured by a halogen moisture analyzer). This invention uses a combined drying method to avoid rapid moisture evaporation caused by single drying, prevent particles from being carried out of fiber gaps by convection impact, and ensure the stability of particle filling position.

[0008] This invention utilizes the pressure of the extrusion rollers to effectively remove excess soaking liquid from the fabric surface. In step S32, most of the moisture is removed by heating and drying to prevent particles from being washed away and displaced. Then, freeze drying is used to reduce the moisture content of the fabric to the target value, maintaining the stability of subsequent processing.

[0009] The preferred operation and process parameters for high-temperature molding in step S4 are as follows: The dried fabric is placed flat into a hot press. During the hot pressing process, the water-based polyurethane softens and melts, forming a continuous "bridging structure" between the particles and fibers, firmly locking the particles into the fiber gaps. The hot pressing temperature is adjusted according to the solid content of the water-based polyurethane: 120-130℃ for 30% solid content, and 140-160℃ for 40-50% solid content; the pressure is adjusted according to the fabric weight: 0.5-0.8 MPa for 250-350 g / m², 0.8-1.2 MPa for 350-500 g / m², and 1.2-1.5 MPa for 500-600 g / m²; the hot pressing time is 10-30 minutes.

[0010] The preferred steps and process parameters for gradient cooling in step S4 are as follows: First, lower the temperature of the hot press to 80℃, hold it at that temperature for 10 minutes, and then allow it to cool naturally to room temperature. This invention utilizes gradient cooling to avoid internal stress in the fabric due to excessive temperature differences, ensuring a firm bond between the modified layer and the fibers, without cracking or peeling.

[0011] The preferred soaking solution containing dispersed filler particles comprises the following substances in parts by mass: 30-50 parts of nano-filler particles; 0.5-1 part of silane coupling agent KH-550; PEG 5-10 parts; 15-25 parts of waterborne polyurethane; 20-40 parts deionized water; Dispersant 0.1-0.3 parts; Anti-settling agent 0.05-0.1 parts; 0.3-0.5 parts of anti-aging agent.

[0012] This invention uses the silane coupling agent KH-550 to modify the surface of nanofilled particles. The silane coupling agent introduces fiber-compatible active groups onto the powder surface, reducing particle surface energy, preventing agglomeration, and simultaneously enhancing chemical bonding with fibers and binders. The dispersant is polyethylene glycol (PEG), with a molecular weight of 200-600 Da, preferably 400 Da, to adjust the system viscosity and promote particle penetration into the fiber gaps. The binder in the impregnation solution of this invention is a thermosetting waterborne polyurethane with a solid content of 30-50%, preferably 40%, a particle size of 50-100 nm, and a Shore A hardness. 80-90; the solvent used in the soaking solution is deionized water; auxiliary additives include polyoxyethylene sorbitan monooleate (Tween-80) as a dispersant (HLB value 15.0), hydroxymethyl cellulose (HMC) as an anti-settling agent (viscosity 20000-50000 mPa·s), and hindered phenolic anti-aging agent 1010, such as BASF Irganox 1010.

[0013] A preferred method for preparing an immersion solution containing dispersed filler particles includes the following steps: S11. Add deionized water to a reactor equipped with a reaction vessel, heat to 30-40℃, add PEG, dispersant (Tween-80), anti-settling agent (HMC) and anti-aging agent, and stir until completely dissolved; stir at 300-500r / min for 5-10 minutes until completely dissolved (no visible particles). S12. Slowly add nano-filled particles coated with silane coupling agent Kh-550, stir and sonicate for 20-30 minutes; break up a small number of agglomerated particles to ensure uniform particle dispersion. Stir at high speed, 800-1200 r / min, and simultaneously turn on the ultrasonic equipment, power 80-150W, frequency 20-40kHz; S13. Add water-based polyurethane, adjust the speed to 300-500 r / min, and stir at low speed for 15-20 minutes to form a uniform and stable soaking solution containing filled particles.

[0014] In this invention, by optimizing the formula and controlling the preparation process, the viscosity of the soaking solution and the surface charge of the particles are adjusted to ensure that the modified powder particles are uniformly suspended in the liquid, avoiding agglomeration and laying the foundation for precise filling.

[0015] The preferred dynamic soaking includes the following steps: S21, Pre-soaking stage The base fabric is completely immersed in an soaking solution containing dispersed filling particles. The temperature is controlled at 25-30℃, the stirring speed is 50r / min, and the soaking time is 1-2 hours. This allows the particles to initially penetrate into the fiber surface gaps, and the fabric water absorption rate reaches 45-50% (by gravimetric method). S22, Filling Stage Heat the fabric to 30-35℃, increase the stirring speed to 80-100r / min, and soak for 2-6 hours. Stretch the fabric during this time, and the fiber gaps will expand to 1.2-1.5 times their unstretched state, reducing the resistance to particle entry and promoting particle penetration into deeper gaps. S23, Locking Phase Cool down to 28-30℃, reduce the stirring speed to 50r / min, and continue soaking for 0.5-1 hour. The filling nanoparticles are adsorbed into the fiber gaps, forming a stable filling state.

[0016] In this invention, nanoparticles are uniformly dispersed in an immersion solution. Through stirring and temperature control, they penetrate into the 0.3μm to 0.8μm gaps between fibers. With stretching, the gaps widen, and the particles penetrate into the fiber gaps inside the fabric. The surface of the nanoparticles is pre-coated with a silane coupling agent KH-550, one end of which can bind to the particle surface, and the other end contains amino and epoxy groups compatible with the surface of polyester, nylon, PE, and other fibers. During the locking stage, the temperature is lowered and the stirring speed is reduced, causing the fiber structure to shrink slightly, "clamping" the particles in the gaps and forming a stable physical lock. Subsequent hot pressing further "welds" the particles into the fiber network through the melting and re-curing of polyurethane.

[0017] In the filling stage of step S22 of this invention, the method of soaking is adjusted according to the fabric weight: 250-350g / ㎡ soaking for 2-3 hours, 350-500g / ㎡ soaking for 3-4 hours, and 500-600g / ㎡ soaking for 4-6 hours; through the above filling operation, the particles in the fiber gaps are initially filled.

[0018] The steps and parameters for stretching the fabric in the preferred step S22 are as follows: Slightly stretch the fabric by 5-8% along both the warp and weft yarns every 30 minutes, at a stretching rate of 4-6 mm / min.

[0019] In this invention, the edges of the soaked fabric are pierced by clamping needles, forming a mechanical interlock. Driven by an external motor, the fabric is stretched at a controlled rate and degree at specific times. The clamps are driven by a servo motor, reciprocating along the guide rail inside the groove to achieve the stretching and release of the fabric.

[0020] Preferably, the fabric is one of high-density polyester, nylon 66, or pure PE fiber knitted fabric with a molecular weight of 1 million to 3 million. The fabric's weave density is ≥30 stitches / inch; The fabric thickness is 1.0-2.5mm; The fiber gap width of the fabric is 0.3-0.8μm.

[0021] Another object of the present invention is to provide an anti-needle-puncture composite material prepared according to the preparation method proposed in the present invention.

[0022] By adopting the above technical solution, the beneficial effects of the present invention are: This invention utilizes a particle modification-system regulation-process synergy technology to deeply fill and firmly lock nanoparticles into the fiber gaps, resulting in a composite fabric with a needle-punch resistance rating of 2-5 and a maximum puncture force of 54N. More importantly, after 10 standard washes, the resistance rating does not decrease by more than 1 level, and the puncture force retention rate is high, reaching 85.2%. This is attributed to the particles being welded to the fiber network by a polyurethane 'bridging structure' rather than being loosely attached to the surface. Therefore, the wash resistance and abrasion resistance far exceed those of traditional surface coatings or simple soaking processes. This invention achieves precise internal filling of the particles, avoiding ineffective accumulation. The thickness increase of the modified fabric compared to its base material is strictly controlled within 0.4-0.5 mm, and the weight increase is less than 15%. Simultaneously, because the fiber pores are not completely blocked, the air permeability remains above 10 mm / s, and the elongation at break is above 15%, ensuring excellent breathability and flexibility. The wearing comfort is far superior to traditional methods that improve protection by increasing thickness or using multiple layers. This invention is applicable to various substrates such as high-density polyester, nylon, and ultra-high molecular weight PE fibers. By adjusting the soaking solution formula and stretching / hot-pressing parameters, it can be adapted to fabrics of different weights and specifications. This invention uses a water-based system throughout the entire process, resulting in low VOC content, an environmentally friendly production process, and products that meet relevant safety standards. The resulting fabrics can be directly used in products such as protective gloves, protective clothing, stab-resistant fabrics, protective shoes, and medical protective goggles. They can also be combined with other fabrics as needed to meet the protection level requirements of different scenarios. Detailed Implementation

[0023] To further explain the technical solution of the present invention, the present invention will be described in detail below through specific embodiments.

[0024] Example 1

[0025] This embodiment discloses a method for preparing a powder-filled anti-needle-puncture composite material, including the following steps: S1. Immerse the fabric in an soaking solution in which filling particles are evenly dispersed. The fabric used in this embodiment is a pure PE fiber knitted fabric with a molecular weight of 2 million, a weight of 250g / ㎡, a knitting density of 30 needles / inch, a thickness of 1.0mm, and a fiber gap width of 0.3μm. The soaking solution containing dispersed filler particles comprises the following substances by mass parts: The mixture contains 30 parts calcium carbonate powder as nanofiller particles, 0.5 parts silane coupling agent KH-550, 5 parts PEG, 15 parts waterborne polyurethane, 40 parts deionized water, 0.1 parts dispersant (Tween-80), 0.05 parts anti-settling agent (HMC), and 0.3 parts anti-aging agent 1010. In this example, the molecular weight of PEG is 400 Da.

[0026] The method for preparing an immersion solution containing dispersed filler particles includes the following steps: S11. Add deionized water to a reactor, heat to 35°C, add PEG, dispersant, anti-settling agent and anti-aging agent, and stir until completely dissolved; S12. Slowly add nano-filled particles coated with silane coupling agent Kh-550, ultrasonic power 120W, frequency 30kHz, stir and ultrasonically treat for 25min; break up a small number of agglomerated particles to ensure uniform particle dispersion. The steps and parameters for coating nanoparticles with silane coupling agent Kh-550 are as follows: Place the nano-filled calcium carbonate particles into a high-speed mixer and add silane coupling agent KH-550. Set the mixer parameters as follows: temperature 90℃, stirring at 650r / min for 30min to ensure that the coupling agent is evenly coated on the particle surface. Place the nano-filled particles coated with silane coupling agent Kh-550 into a hot air oven and dry at 110℃ for 2.5h. After cooling, pass them through a 2000-mesh sieve to remove a small amount of agglomerated particles. S13. Add water-based polyurethane, adjust the speed to 400 r / min, and stir at low speed for 20 minutes to form a uniform and stable soaking solution containing filled particles.

[0027] The viscosity of the resulting soaking solution containing the packed particles was 25 mPa·s, and the coefficient of variation of the particle size distribution was less than or equal to 0.2. S2. The fabric is dynamically soaked in an immersion solution containing dispersed filling particles. Through pre-soaking, stretching, filling, adsorption, cooling and locking, the nano filling particles fill the middle of the fabric fibers. Dynamic soaking includes the following steps: S21, Pre-soaking stage The base fabric is completely immersed in an soaking solution containing dispersed filling particles, and pre-soaked at 28°C for 1.5 hours (50 r / min). S22, Filling Stage Fill at 32℃ for 3 hours, at 90 r / min, the fabric stretches by 6% every 30 minutes.

[0028] S23, Locking Phase Lock at 30℃ for 1 hour (50 r / min).

[0029] S3, Drying; Step S3 drying includes the following steps: S31. Take out the soaked fabric and remove excess soaking liquid from the surface by squeezing rollers to control the liquid content of the fabric to 34% (by weight method). S32, dried at 70℃ for 1.5h, then freeze-dried under vacuum at -45℃ for 10h, with a moisture content of 3.8%.

[0030] S4, high-temperature molding and gradient cooling, yield the target needle-punch resistant composite material.

[0031] The operation and process parameters for high-temperature molding in step S4 are as follows: After drying, the fabric is placed flat into a hot press at 135℃ and 0.9MPa for 18 minutes. During the hot pressing process, the water-based polyurethane softens and melts, forming a continuous bridging structure between the particles and fibers, locking the particles in the fiber gaps.

[0032] The steps and process parameters for gradient cooling in step S4 are as follows: First, lower the temperature of the hot press to 80℃, keep it warm for 10 minutes, and then let it cool naturally to room temperature.

[0033] Example 2

[0034] This embodiment discloses a method for preparing a powder-filled anti-needle-puncture composite material. Includes the following steps: S1. Immerse the fabric in an soaking solution in which filling particles are evenly dispersed. The fabric used in this embodiment is a high-density polyester fiber knitted fabric with a weight of 350g / ㎡, a knitting density of 32 stitches / inch, a thickness of 1.5mm, and a fiber gap width of 0.5μm. The soaking solution containing dispersed filler particles comprises the following substances by mass parts: The ingredients included 38 parts talc powder as nanofiller particles, 0.7 parts silane coupling agent KH-550, 7 parts PEG, 19 parts waterborne polyurethane, 34 parts deionized water, 0.2 parts dispersant (Tween-80), 0.07 parts anti-settling agent (HMC), and 0.4 parts anti-aging agent 1010; in this example, the molecular weight of PEG was 400 Da.

[0035] The method for preparing an immersion solution containing dispersed filler particles includes the following steps: S11. Add deionized water to a reactor, heat to 35°C, add PEG, dispersant, anti-settling agent and anti-aging agent, and stir until completely dissolved; S12. Slowly add nano-filled particles coated with silane coupling agent Kh-550, ultrasonic power 120W, frequency 30kHz, stir and ultrasonically treat for 25min; break up a small number of agglomerated particles to ensure uniform particle dispersion. The steps and parameters for coating nanoparticles with silane coupling agent Kh-550 are as follows: Place the nano-filled calcium carbonate particles into a high-speed mixer and add silane coupling agent KH-550. Set the mixer parameters as follows: temperature 90℃, stirring at 650r / min for 45min to ensure that the coupling agent is evenly coated on the particle surface. Place the nano-filled particles coated with silane coupling agent Kh-550 into a hot air oven and dry at 110℃ for 2.5h. After cooling, pass them through a 2000-mesh sieve to remove a small amount of agglomerated particles. S13. Add water-based polyurethane, adjust the speed to 400 r / min, and stir at low speed for 20 minutes to form a uniform and stable soaking solution containing filled particles.

[0036] The viscosity of the resulting soaking solution containing the packed particles was 25 mPa·s, and the coefficient of variation of the particle size distribution was less than or equal to 0.2. S2. The fabric is dynamically soaked in an immersion solution containing dispersed filling particles. Through pre-soaking, stretching, filling, adsorption, cooling and locking, the nano filling particles fill the middle of the fabric fibers. Dynamic soaking includes the following steps: S21, Pre-soaking stage The base fabric is completely immersed in an soaking solution containing dispersed filling particles, and pre-soaked at 28°C for 1.5 hours (50 r / min). S22, Filling Stage Fill at 32℃ for 3 hours (90r / min, stretching 6% every 30min).

[0037] S23, Locking Phase Lock at 30℃ for 1 hour (50 r / min).

[0038] S3, Drying; Step S3 drying includes the following steps: S31. Take out the soaked fabric and remove excess soaking liquid from the surface by squeezing rollers to control the liquid content of the fabric to 34% (by weight method). S32, dried at 70℃ for 1.5h, then freeze-dried under vacuum at -45℃ for 10h, with a moisture content of 3.8%.

[0039] S4, high-temperature molding and gradient cooling, yield the target needle-punch resistant composite material.

[0040] The operation and process parameters for high-temperature molding in step S4 are as follows: After drying, the fabric is placed flat into a hot press at 135℃ and 0.9MPa for 18 minutes. During the hot pressing process, the water-based polyurethane softens and melts, forming a continuous bridging structure between the particles and fibers, locking the particles in the fiber gaps.

[0041] The steps and process parameters for gradient cooling in step S4 are as follows: First, lower the temperature of the hot press to 80℃, keep it warm for 10 minutes, and then let it cool naturally to room temperature.

[0042] Example 3

[0043] This embodiment discloses a method for preparing a powder-filled anti-needle-puncture composite material, including the following steps: S1. Immerse the fabric in an soaking solution in which filling particles are evenly dispersed. The pure PE fiber knitted fabric in this embodiment has a molecular weight of 2.5 million, a weight of 450 g / m², a knitting density of 35 needles / inch, a thickness of 2.0 mm, and a fiber gap width of 0.6 μm. The soaking solution containing dispersed filler particles comprises the following substances by mass parts: The composition includes 42 parts of ultrafine silica lime as nanofiller particles, 0.8 parts of silane coupling agent KH-550, 8 parts of PEG, 22 parts of waterborne polyurethane, 27 parts of deionized water, 0.25 parts of dispersant (Tween-80), 0.08 parts of anti-settling agent (HMC), and 0.4 parts of anti-aging agent 1010. In this example, the molecular weight of PEG is 400 Da.

[0044] The method for preparing an immersion solution containing dispersed filler particles includes the following steps: S11. Add deionized water to a reactor, heat to 35°C, add PEG, dispersant, anti-settling agent and anti-aging agent, and stir until completely dissolved; S12. Slowly add nano-filled particles coated with silane coupling agent Kh-550, and perform ultrasonic treatment with stirring and ultrasound for 30 minutes at an ultrasonic power of 140W and a frequency of 35kHz; break up a small number of agglomerated particles to ensure uniform particle dispersion. The steps and parameters for coating nanoparticles with silane coupling agent Kh-550 are as follows: Place the nano-filled calcium carbonate particles into a high-speed mixer and add silane coupling agent KH-550. Set the mixer parameters as follows: temperature 95℃, stirring at 700r / min for 50min to ensure that the coupling agent is evenly coated on the particle surface. Place the nano-filled particles coated with silane coupling agent Kh-550 into a hot air oven and dry at 115℃ for 2h. After cooling, pass them through a 2000-mesh sieve to remove a small amount of agglomerated particles. S13. Add water-based polyurethane, adjust the speed to 400 r / min, and stir at low speed for 20 minutes to form a uniform and stable soaking solution containing filled particles.

[0045] The viscosity of the resulting soaking solution containing the packed particles was 28 mPa·s, and the coefficient of variation of the particle size distribution was less than or equal to 0.2. S2. The fabric is dynamically soaked in an immersion solution containing dispersed filling particles. Through pre-soaking, stretching, filling, adsorption, cooling and locking, the nano filling particles fill the middle of the fabric fibers. Dynamic soaking includes the following steps: S21, Pre-soaking stage The base fabric is completely immersed in the soaking solution containing dispersed filling particles, and pre-soaked at 30°C for 2 hours (50 r / min). S22, Filling Stage Fill at 35℃ for 4 hours (100r / min, stretching 7% every 30min).

[0046] S23, Locking Phase Lock at 30℃ for 1 hour (50 r / min).

[0047] S3, Drying; Step S3 drying includes the following steps: S31. Take out the soaked fabric and remove excess soaking liquid from the surface by squeezing rollers to control the liquid content of the fabric to 37% (by weight method). S32, dried at 70℃ for 2 hours, then freeze-dried under vacuum at -50℃ for 12 hours, with a moisture content of 3.2%.

[0048] S4, high-temperature molding and gradient cooling, yield the target needle-punch resistant composite material.

[0049] The operation and process parameters for high-temperature molding in step S4 are as follows: After drying, the fabric is placed flat into a hot press and hot-pressed at the following parameters: 145℃, 1.2MPa, 22 minutes. During the hot pressing process, the water-based polyurethane softens and melts, forming a continuous bridging structure between the particles and fibers, locking the particles in the fiber gaps.

[0050] The steps and process parameters for gradient cooling in step S4 are as follows: First, lower the temperature of the hot press to 80℃, keep it warm for 10 minutes, and then let it cool naturally to room temperature.

[0051] Example 4

[0052] This embodiment discloses a method for preparing a powder-filled anti-needle-puncture composite material. Includes the following steps: S1. Immerse the fabric in an soaking solution in which filling particles are evenly dispersed. The fabric used in this embodiment is an ultra-high molecular weight PE fiber knitted fabric with a molecular weight of 3 million, a weight of 600g / ㎡, a knitting density of 38 stitches / inch, a thickness of 2.5mm, and a fiber gap width of 0.8μm. The soaking solution containing dispersed filler particles comprises the following substances by mass parts: The composition includes 50 parts of ultrafine silica lime as nanofiller particles, 1 part of silane coupling agent KH-550, 10 parts of PEG, 25 parts of waterborne polyurethane, 20 parts of deionized water, 0.3 parts of dispersant (Tween-80), 0.1 parts of anti-settling agent (HMC), and 0.5 parts of anti-aging agent 1010. In this example, the molecular weight of PEG is 400 Da.

[0053] The method for preparing an immersion solution containing dispersed filler particles includes the following steps: S11. Add deionized water to a reactor, heat to 35°C, add PEG, dispersant, anti-settling agent and anti-aging agent, and stir until completely dissolved; S12. Slowly add nano-filled particles coated with silane coupling agent Kh-550, ultrasonic power 150W, frequency 40kHz, stir and ultrasonically treat for 30min; break up a small number of agglomerated particles to ensure uniform particle dispersion. The steps and parameters for coating nanoparticles with silane coupling agent Kh-550 are as follows: Place the nano-filled calcium carbonate particles into a high-speed mixer and add silane coupling agent KH-550. Set the mixer parameters as follows: temperature 100℃, stirring at 800r / min for 60min to ensure that the coupling agent is evenly coated on the particle surface. Place the nano-filled particles coated with silane coupling agent Kh-550 into a hot air oven and dry at 120℃ for 2h. After cooling, pass them through a 2000-mesh sieve to remove a small amount of agglomerated particles. S13. Add water-based polyurethane, adjust the speed to 400 r / min, and stir at low speed for 20 minutes to form a uniform and stable soaking solution containing filled particles.

[0054] The viscosity of the resulting soaking solution containing the packed particles was 32 mPa·s, and the coefficient of variation of the particle size distribution was less than or equal to 0.2. S2. The fabric is dynamically soaked in an immersion solution containing dispersed filling particles. Through pre-soaking, stretching, filling, adsorption, cooling and locking, the nano filling particles fill the middle of the fabric fibers. Dynamic soaking includes the following steps: S21, Pre-soaking stage The base fabric is completely immersed in the soaking solution containing dispersed filling particles, and pre-soaked at 30°C for 2 hours (50 r / min). S22, Filling Stage Fill at 35℃ for 6 hours (100r / min, stretching 8% every 30min).

[0055] S23, Locking Phase Lock at 30℃ for 1 hour (50 r / min).

[0056] S3, Drying; Step S3 drying includes the following steps: S31. Take out the soaked fabric and remove excess soaking liquid from the surface by squeezing rollers to control the liquid content of the fabric to 36% (by weight method). S32, dried at 80℃ for 2 hours, then freeze-dried under vacuum at -50℃ for 12 hours, with a moisture content of 3.0%.

[0057] S4, high-temperature molding and gradient cooling, yield the target needle-punch resistant composite material.

[0058] The operation and process parameters for high-temperature molding in step S4 are as follows: After drying, the fabric is placed flat into a hot press. The hot pressing parameters are: 160℃, 1.5MPa, 30 minutes. During the hot pressing process, the water-based polyurethane softens and melts, forming a continuous bridging structure between the particles and fibers, locking the particles in the fiber gaps.

[0059] The steps and process parameters for gradient cooling in step S4 are as follows: First, lower the temperature of the hot press to 80℃, keep it warm for 10 minutes, and then let it cool naturally to room temperature.

[0060] Comparative Example The main difference between this comparative example and Example 1 is that a static soaking process is used: the fabric is immersed in the same soaking solution as in Example 1 and continuously soaked for 5.5 hours under the conditions of 28°C and 50r / min stirring, without any stretching operation, and the other process conditions are the same as in Example 1.

[0061] Performance tests were conducted on the composite fabrics obtained in Examples 1 to 4 and the comparative example, respectively. The specific performance test methods are as follows: The anti-puncture level is determined by using a standard puncture probe with a diameter of 1.0 mm and a tip angle of 30° according to ASTM F2878-19 of the American standard. The probe punctures the fabric at a speed of 50 mm / min, and the puncture force is recorded. The level is judged according to the standard (Level 1: ≥10 N; Level 2: ≥20 N; Level 3: ≥30 N; Level 4: ≥40 N; Level 5: ≥50 N). For air permeability, referring to GB / T 5453-1997, an air permeability tester is used to measure the air permeability of the fabric under a pressure of 100 Pa (unit: mm / s), and the ratio to the air permeability of the base material is calculated.

[0062] For flexibility, referring to GB / T 3923.1-2013, a fabric tensile testing machine is used to test the breaking elongation rates of the warp and weft directions of the fabric, and the average value of 3 tests is taken.

[0063] For wear resistance, referring to GB / T 21196.2-2007, a Martindale wear tester is used to test the number of wear-resistant cycles of the fabric under a pressure of 20 kPa until the fabric is damaged.

[0064] For the bond firmness, the composite material is put into a washing machine and washed 10 times at a water temperature of 40°C with a standard washing program. After drying, the anti-puncture level is tested. A decrease in level ≤1 is considered qualified (simulating the washing scenario in actual use). The specific test data are shown in Table 1.

[0065] Table 1 Performance test data of the composite fabrics obtained in Examples 1 to 4 and the comparative example Test Project Example 1 Example 2 Example 3 Example 4 Comparative Example Needle prick test level Level 2 Level 3 Level 4 Level 5 Level 1 Needle puncture force (N) 25 33 45 54 18 Needle puncture level after 10 washes Level 2 Level 2 Level 3 Level 4 Level 0 Needle puncture force (N) after washing 23 25 36 46 7 Air permeability (mm / s) 18 15 12 10 10 Elongation at break (%) 19 16 15 15 12 Thickness (mm) 1.4 1.9 2.4 2.9 3.5 Through the three-stage technology of particle modification - system regulation - process coordination, the controllable, deep filling and firm locking of nano-filling particles in the fiber gaps are achieved. As shown in Table 1, the ASTM F2878 puncture test level of the obtained composite material can reach Level 2 to Level 5, and the highest puncture force can reach 54 N. After 10 standard washings, not only does the level decrease by no more than 1, but the retention rate of the puncture force after washing is high. For example, the retention rate of Example 4 is 85.2%, which proves excellent protective durability. The increase in the thickness of the modified fabric in each example compared to its own base material is less than 0.5 mm, and the weight increase is less than 15%. Moreover, the air permeability of Examples 1 to 4 exceeds 10 mm / s, and the breaking elongation rate exceeds 15%. The composite fabric prepared by the present invention well maintains its air permeability and flexibility, and has high wearing comfort.

[0066] Further analysis of Table 1 reveals that in Examples 1 to 4, the needle-punch resistance and puncture force of the composite material progressively increase with increasing fabric weight, the amount of nanoparticles used, and the corresponding increases in hot-pressing pressure and temperature. This indicates that through process synergy, higher-weight fabrics can carry and lock in more nanoparticles, thereby forming a more effective puncture-resistant barrier. Although the comparative example showed a significant increase in thickness to 3.5 mm and achieved a puncture force of 23 N, a large amount of particles were lost after washing, causing the puncture force to plummet to 7 N after washing. This indicates that the performance mainly relies on the loose accumulation of particles on the fabric surface rather than effective filling of fiber gaps, resulting in a large amount of particle loss and a sharp decline in performance after washing. The above data changes highlight the necessity of the "dynamic soaking and stretching" process of this invention for achieving deep particle filling and secure locking.

Claims

1. A method for preparing a nanopowder-filled anti-needle-puncture composite material, characterized in that: Includes the following steps: S1. Immerse the fabric in an soaking solution in which filling particles are evenly dispersed. The viscosity of the resulting soaking solution containing the dispersed filler particles was 18-32 mPa·s; The nanofiller particles include one or more of calcium carbonate powder, talc powder, and ultrafine silica lime. S2. The fabric is dynamically soaked in an immersion solution containing dispersed filling particles. Through pre-soaking, stretching, filling, adsorption, cooling and locking, the nano filling particles fill the middle of the fabric fibers. S3, Drying; S4, high-temperature molding and gradient cooling, yield the target needle-punch resistant composite material.

2. The preparation method according to claim 1, characterized in that: Step S3 drying includes the following steps: S31. Remove the soaked fabric and remove excess soaking liquid from the surface using a squeezing roller, controlling the liquid retention rate of the fabric to 30-40%. Dry in an oven at 60-80℃ for 1-2 hours, then transfer to a vacuum freeze dryer at -40 to -50℃ and a vacuum degree of -0.08 to -0.1MPa for 8-12 hours.

3. The preparation method according to claim 1, characterized in that: The operation and process parameters for high-temperature molding in step S4 are as follows: After drying, place the fabric flat into a hot press and press for 10-30 minutes. During the hot pressing process, the water-based polyurethane softens and melts, forming a continuous bridging structure between the particles and fibers, locking the particles in the fiber gaps.

4. The preparation method according to claim 1, characterized in that: The steps and process parameters for gradient cooling in step S4 are as follows: First, lower the temperature of the hot press to 80℃, keep it warm for 10 minutes, and then let it cool naturally to room temperature.

5. The preparation method according to claim 1, characterized in that: The soaking solution containing dispersed filler particles comprises the following substances by mass parts: 30-50 parts of nano-filler particles; 0.5-1 part of silane coupling agent KH-550; PEG 5-10 parts; 15-25 parts of waterborne polyurethane; 20-40 parts deionized water; Dispersant 0.1-0.3 parts; Anti-settling agent 0.05-0.1 parts; 0.3-0.5 parts of anti-aging agent.

6. The preparation method according to claim 1, characterized in that: The method for preparing an immersion solution containing dispersed filler particles includes the following steps: S11. Add deionized water to a reactor, heat to 30-40℃, add PEG, dispersant, anti-settling agent and anti-aging agent, and stir until completely dissolved; S12. Slowly add nano-filled particles coated with silane coupling agent Kh-550, and stir and sonicate for 20-30 minutes. S13. Add water-based polyurethane, adjust the speed to 300-500 r / min, and stir at low speed for 15-20 minutes to form a uniform and stable soaking solution containing filled particles.

7. The preparation method according to claim 1, characterized in that: Dynamic soaking includes the following steps: S21, Pre-soaking stage The base fabric is completely immersed in an soaking solution containing dispersed filling particles. The temperature is controlled at 25-30℃, the stirring speed is 50r / min, and the soaking time is 1-2 hours. This allows the particles to initially penetrate into the fiber surface gaps, and the fabric water absorption rate reaches 45-50%. S22, Filling Stage Heat to 30-35℃, increase stirring speed to 80-100r / min, soak for 2-6 hours, during which the fabric is stretched, the fiber gaps expand, and the particles penetrate into the deep gaps. S23, Locking Phase Cool down to 28-30℃, reduce the stirring speed to 50r / min, and continue soaking for 0.5-1 hour. The filling nanoparticles are adsorbed into the fiber gaps, forming a stable filling state.

8. The preparation method according to claim 7, characterized in that: The steps and parameters for stretching the fabric in step S22 are as follows: Slightly stretch the fabric by 5-8% along both the warp and weft yarns every 30 minutes, at a stretching rate of 4-6 mm / min.

9. The preparation method according to claim 1, characterized in that: The fabric is one of high-density polyester, nylon 66, and pure PE fiber knitted fabric with a molecular weight of 1 million to 3 million. The fabric's weave density is ≥30 stitches / inch; The fabric thickness is 1.0-2.5mm; The fiber gap width of the fabric is 0.3-0.8μm.

10. A needle-resistant composite material prepared according to any one of claims 1 to 9.