Individual-soldier flexible tactical skin with multi-spectrum stealth and dynamic impact resistance functions and preparation method of individual-soldier flexible tactical skin

Abstract

The invention discloses a single-soldier flexible tactical skin with multi-spectrum stealth and dynamic impact resistance functions and a preparation method thereof, and belongs to the technical field of special protective equipment. The individual soldier flexible tactical skin comprises a fiber fabric matrix impregnated with a shear thickening fluid, wherein the shear thickening fluid comprises a liquid dispersion medium, hard dispersion phase particles, electromagnetic loss type dispersion phase particles and polylysine. During preparation, the polylysine is used as a bridge structure, and the electromagnetic loss type functional filler, the hard dispersed phase nanoparticles and the liquid dispersion medium are uniformly mixed under high-speed stirring and ultrasonic assistance to obtain the functionalized shear thickening fluid. The contradiction among light weight, comfort and multifunctional protection of traditional individual soldier protection equipment is effectively solved, and endogenous fusion of the dynamic impact resistance function and the efficient electromagnetic stealth function is successfully achieved in a single flexible material system.

Description

Technical Field

[0001] This invention relates to the field of special protective equipment technology, specifically to a flexible tactical skin for individual soldiers and its preparation method. Background Technology

[0002] With the increasing complexity of modern warfare, individual soldier protective equipment faces unprecedented challenges. Battlefield threats are no longer limited to traditional kinetic energy attacks (such as shrapnel, bayonets, and low-velocity bullets), but also include increasingly severe electromagnetic spectrum threats (such as battlefield reconnaissance radar detection and high-intensity electromagnetic interference). Therefore, developing a new generation of individual soldier protective materials that combine highly efficient physical protection capabilities with excellent electromagnetic stealth / shielding functions has become an urgent need in the field of defense science and technology.

[0003] Currently, traditional individual soldier physical protective materials are mainly divided into two categories: hard protection and soft protection. While hard protection (such as ceramic inserts and metal composite plates) offers excellent impact resistance, it suffers from drawbacks such as heavy weight, high rigidity, and poor breathability, severely limiting soldiers' tactical maneuverability and making it unsuitable for prolonged wear. Soft protection (such as multi-layered Kevlar or ultra-high molecular weight polyethylene fabrics), while offering better flexibility, often requires stacking dozens of layers to achieve sufficient protection levels, resulting in bulky and heavy equipment. Furthermore, its effectiveness against sharp object impacts or high-speed fragment penetration is limited.

[0004] To resolve the conflict between protection and comfort, "liquid armor" technology based on shear-thickening fluids (STFs) has emerged. STFs are typical non-Newtonian fluids, existing as liquids under normal conditions but instantly transforming into near-solid states upon high-speed shearing or impact, capable of absorbing and dissipating significant impact energy. Impregnating STFs into high-performance fiber fabrics can create intelligent flexible materials that are soft and comfortable under normal conditions but harden instantly to provide protection during attacks. However, traditional STF systems typically consist of dielectric particles such as silica dispersed in polyethylene glycol, both of which are electromagnetic wave transmitting materials. Therefore, existing STF flexible protective materials are electromagnetically "transparent," lacking radar absorption stealth or electromagnetic shielding capabilities, and are unable to cope with the threats of modern electronic warfare.

[0005] On the other hand, most existing electromagnetic absorbing materials exist in the form of coatings, plates, or simple conductive fabrics. Absorbing coatings have poor adhesion and are prone to peeling off during tactical operations; absorbing plates are rigid and heavy; and while ordinary conductive fiber fabrics have shielding functions, their mechanical strength is low and they lack dynamic impact resistance.

[0006] In summary, there is an urgent need in the current technological field for a flexible material system that can integrate dynamic mechanical shock resistance with broadband electromagnetic wave absorption to solve the technical bottleneck of existing individual soldier equipment in achieving a balance between lightweight, comfort, physical protection, and electromagnetic stealth. Summary of the Invention

[0007] To address the shortcomings of existing flexible protective materials for individual soldiers, which offer limited functionality and struggle to simultaneously provide dynamic mechanical impact resistance and battlefield electromagnetic stealth, this invention aims to provide a flexible tactical skin and its fabrication method that combines multi-spectral stealth, electromagnetic wave absorption, and dynamic impact resistance. This material seeks to overcome the challenges of traditional "liquid armor" lacking electromagnetic transparency and stealth capabilities, while traditional wave-absorbing materials lack dynamic mechanical protection, thus achieving integrated "soft-hard conversion" protection and "electromagnetic stealth."

[0008] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0009] The individual flexible tactical skin includes a fibrous fabric matrix impregnated with a shear-thickening fluid, said shear-thickening fluid being a stable solid-liquid suspension comprising: a liquid dispersion medium; hard dispersed phase particles; electromagnetically depleting dispersed phase particles; and polylysine (PLL).

[0010] Further, the liquid dispersion medium is polyethylene glycol (PEG) or polypropylene glycol (PPG); the hard dispersed phase particles are fumed silica or monodisperse polymer microspheres; and the fiber fabric matrix is ​​aramid fiber fabric (Kevlar), ultra-high molecular weight polyethylene fiber fabric (UHMWPE), or poly(p-phenylenebenzodioxazole) fiber fabric (PBO).

[0011] Furthermore, the electromagnetic loss-type dispersed phase particles are micro- and nano-sized, uniformly dispersed in the liquid dispersion medium, imparting electromagnetic wave absorption capability to the material, and are selected from one or more of the following: magnetic metal / alloy micro- and nano-powders (such as carbonyl iron powder, iron-nickel alloy powder), magnetic oxide particles (such as iron(II,III) oxide, ferrite), carbon-based conductive / magnetic materials (such as carbon nanotubes, graphene, porous carbon or carbon materials loaded with metal single atoms), and two-dimensional transition metal carbon / nitrides (MXenes).

[0012] Furthermore, the mass percentages of each component in the shear-thickening fluid are as follows: 30%-55% liquid dispersion medium, 35%-60% hard dispersed phase particles, 1%-20% electromagnetic loss type dispersed phase particles, and 1%-5% polylysine.

[0013] Furthermore, the mass percentages of the components of the shear-thickening fluid are as follows: 43% liquid dispersion medium, 40% hard dispersed phase particles, 15% electromagnetic loss type dispersed phase particles, and 2% polylysine.

[0014] The aforementioned method for preparing individual flexible tactical skin includes the following steps: placing a liquid dispersion medium in a container, adding polylysine for reaction, and then, under mechanical stirring, alternately adding hard dispersed phase particles and electromagnetically depleting dispersed phase particles in batches to form a mixed slurry. Subsequently, the mixed slurry is subjected to high-shear dispersion treatment and high-energy ultrasonic crushing treatment to break up particle agglomeration and obtain a dispersion liquid. The dispersion liquid is subjected to vacuum degassing treatment to obtain a shear-thickening fluid precursor. The shear-thickening fluid precursor is used to impregnate a fiber fabric matrix to obtain the individual flexible tactical skin.

[0015] Furthermore, the reaction conditions between the liquid dispersion medium and polylysine are as follows: reaction at 25-40°C for 12-24 hours under an inert atmosphere.

[0016] Furthermore, the high-shear dispersion treatment specifically involves a rotation speed of 1000-5000 rpm and a time of 30-120 min; the high-energy ultrasonic fragmentation treatment specifically involves an ultrasonic power of 200-1000 W and an ultrasonic time of 30-90 min.

[0017] Furthermore, the specific method for impregnating the fiber fabric matrix using a shear-thickening fluid precursor is as follows: To overcome the defect that high-viscosity fluids are difficult to penetrate dense fabrics, the shear-thickening fluid precursor is first mixed with a volatile solvent (such as anhydrous ethanol or acetone) and diluted. This is then prepared into a diluted impregnation solution with low viscosity and high fluidity by magnetic stirring. The fiber fabric matrix is ​​then completely immersed in the solution until it is saturated. Afterward, it is removed, dried, and shaped, allowing the volatile solvent to completely evaporate, while the shear-thickening system remains and anchored in the fiber gaps, resulting in the aforementioned individual flexible tactical skin.

[0018] The aforementioned application of individual flexible tactical skin in the preparation of individual bulletproof vest pads, tactical knee pads, tactical elbow pads, flexible exoskeleton armor and helmets.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Multifunctional integrated design: This invention successfully achieves the endogenous integration of dynamic impact resistance and efficient electromagnetic stealth function within a single flexible material system. Compared with the traditional simple superposition structure of "bulletproof layer + wave-absorbing layer", the integrated structure of this invention is thinner, more stable, and does not have the risk of interlayer delamination.

[0020] (2) Synergistic Enhancement Mechanism of Fillers: This invention cleverly utilizes the physical properties of electromagnetically depleting particles. They not only endow the material with excellent radar absorption performance, but also participate in the shear thickening process as hard particles. Polylysine copolymerizes with PEG or PPG to form a PLL-PEG(PPG)-OH bridge structure. The amino groups on the surface of PLL covalently bond with the functional groups on the surface of magnetic nanoparticles, and hydrogen bonds are formed between the -OH groups and the hydroxyl groups on the surface of silica. Ultimately, while retaining the unique rheological characteristics of the shear thickening fluid system, the stability of the system is greatly enhanced. Experiments show that the addition of electromagnetically depleting particles and polylysine can further enhance the shear thickening response amplitude and energy absorption effect of STF, and the performance is relatively stable.

[0021] (3) Excellent tactical adaptability: Under normal conditions, the material maintains the flexibility, breathability and comfort of the fabric, without affecting the individual soldier's tactical movements; when encountering sudden high strain rate impacts (such as fragments or falls), it can instantly "lock" and harden to provide protection, perfectly meeting the dual requirements of equipment comfort and safety in complex battlefield environments.

[0022] (4) The flexible tactical protective skin prepared by this invention achieves the goal of lightweight flexibility, dynamic high impact resistance, and excellent broadband stealth performance through the synergistic design optimization of the functional filler system and the matrix fabric. The raw materials involved in this invention are widely available, the preparation process is mature and controllable, and it is easy to achieve large-scale production with significant effects. The flexible protective skin prepared by this invention can be widely used in individual soldier tactical combat uniforms, flexible exoskeleton armor, communication equipment, etc., and can effectively improve the battlefield survivability and electromagnetic stealth of our army's individual soldiers and equipment in complex battlefield environments. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the wave absorption test of the flexible tactical skin of the present invention in the 8-12X frequency band. Detailed Implementation

[0024] The present invention will be further described below with reference to specific embodiments.

[0025] The raw materials used in the following embodiments are: Polyethylene glycol 200, CAS No.: 25322-68-3; Polypropylene glycol 400, CAS No. 25322-69-4; Hydrophilic fumed silica, CAS No.: 112945-52-5; Carbonyl iron powder, YW Type 1, manufactured by Jiangsu Tianyi Ultrafine Metal Powder Co., Ltd. Iron-nickel alloy powder, with an iron-nickel content ratio of approximately 1:1, was purchased from Shanghai Chaowei Nanotechnology Co., Ltd. The remaining raw materials are all commercially available products.

[0026] Example 1 This embodiment describes the preparation of a flexible protective skin using Kevlar 49 aramid fiber fabric as the matrix and impregnated internally with a multifunctional shear-thickening fluid containing carbonyl iron powder (CIP). The specific preparation steps are as follows: Step 1: Preparation of Multifunctional Shear-Thickening Fluid Precursor (“Thick Slurry”) 20043 parts by weight of polyethylene glycol 40 parts by weight of hydrophilic fumed silica 15 parts by weight of carbonyl iron powder Preliminary mixing: Pour the weighed PEG200 into a 250mL beaker equipped with a mechanical stirrer, add 2 parts by weight of polylysine, and react under an inert atmosphere at 30°C for 20 hours. Then, under low-speed stirring (300rpm), slowly and in batches add fumed silica powder, and add carbonyl iron powder after it is basically wetted. After the addition is complete, increase the speed to 1500rpm and stir continuously for 60 minutes to obtain a preliminarily mixed viscous slurry.

[0027] Co-dispersion treatment: Place the beaker containing the slurry under the probe of a high-energy ultrasonic cell disruptor (power 600W, 5s working / 3s intermittent) and perform ultrasonic dispersion treatment for 45 minutes under ice-water bath cooling conditions to break up the agglomeration of nanoparticles and ensure uniform distribution of iron powder.

[0028] Vacuum degassing: Transfer the well dispersed slurry to a vacuum drying oven, evacuate to an absolute pressure of -0.1 MPa at room temperature, and maintain for 60 minutes until no obvious bubbles escape from the surface of the slurry, to obtain a multifunctional STF precursor with a dark gray appearance and extremely high viscosity.

[0029] Step 2: Preparation of low-viscosity impregnation solution Take 100.0 parts by weight of the prepared multifunctional STF precursor and add an equal part by weight of anhydrous ethanol. Stir with a magnetic stirrer at 800 rpm for 30 minutes until a smooth, uniform, stable, milky gray, low-viscosity impregnation solution is formed.

[0030] Step 3: Assist in enhancing the impregnation process Substrate preparation: Cut a piece of plain weave fiber fabric with a size of 30cm×30cm, clean the surface oil with acetone and dry it for later use.

[0031] The above-mentioned flexible fiber fabric is completely immersed in the diluted impregnation solution obtained in step two, and vacuum-pressurized circulation is used for permeation: vacuum is drawn to remove the air inside the fabric, and then normal pressure is restored or positive pressure is applied, and the liquid is forced into the fiber using the pressure difference; the impregnation treatment time is 5 hours until the fabric is saturated with liquid.

[0032] Step 4: Controlled curing and setting Remove excess liquid: Take out the saturated impregnated fabric and pass it through a pair of adjustable-gap rubber rollers, adjusting the pressure to remove excess impregnation liquid from the fabric surface and between layers.

[0033] Gradient drying: Lay the fabric flat in a forced-air drying oven. First, pre-dry at 60°C for 2 hours to allow most of the ethanol to evaporate slowly and prevent rapid pore closure; then raise the temperature to 80°C and continue drying for 6 hours until the fabric quality is constant (indicating complete removal of ethanol and residual PEG system).

[0034] Finished product acquisition: The sample was removed and allowed to cool naturally to room temperature, resulting in a finished flexible tactical protective skin that is dark gray in appearance, soft and thick to the touch, and has magnetic adsorption properties.

[0035] Example 2 This embodiment describes the preparation of a flexible protective skin using ultra-high molecular weight polyethylene fiber fabric as the matrix and impregnated with a multifunctional shear-thickening fluid containing iron-nickel alloy powder. The specific preparation steps are as follows: Step 1: Preparation of shear-thickening fluid precursor Polypropylene glycol 40040 parts by weight 46 parts by weight of hydrophilic fumed silica 10 parts by weight of iron-nickel alloy powder Preliminary mixing: Pour the weighed PEG200 into a 250mL beaker equipped with a mechanical stirrer, add 4 parts by weight of polylysine, and react under an inert atmosphere at 35°C for 15 hours. Then, under low-speed stirring (300rpm), slowly and in batches add fumed silica powder, and add carbonyl iron powder after it is basically wetted. After the addition is complete, increase the speed to 1500rpm and stir continuously for 60 minutes to obtain a preliminarily mixed viscous slurry.

[0036] Co-dispersion treatment: Place the beaker containing the slurry under the probe of a high-energy ultrasonic cell disruptor (power 800W, 5s working / 3s intermittent) and perform ultrasonic dispersion treatment for 40 minutes under ice-water bath cooling conditions to break up the agglomeration of nanoparticles and ensure uniform distribution of iron powder.

[0037] Vacuum degassing: Transfer the well dispersed slurry to a vacuum drying oven, evacuate to an absolute pressure of -0.1 MPa at room temperature, and maintain for 60 minutes until no obvious bubbles escape from the surface of the slurry, to obtain a multifunctional STF precursor with a dark gray appearance and extremely high viscosity.

[0038] Step 2: Preparation of low-viscosity impregnation solution Take 100.0 parts by weight of the prepared multifunctional STF precursor and add 80.0 parts by weight of anhydrous ethanol. Stir with a magnetic stirrer at 800 rpm for 30 minutes until a smooth, uniform, stable, milky gray, low-viscosity impregnation solution is formed.

[0039] Step 3: Assist in enhancing the impregnation process Substrate preparation: Cut a piece of plain weave fiber fabric with a size of 30cm×30cm, clean the surface oil with acetone and dry it for later use.

[0040] The above-mentioned flexible fiber fabric is completely immersed in the diluted impregnation solution obtained in step two, and vacuum-pressurized circulation is used for permeation: vacuum is drawn to remove the air inside the fabric, and then normal pressure is restored or positive pressure is applied, and the liquid is forced into the fiber using the pressure difference; the impregnation treatment time is 8 hours until the fabric is saturated with liquid.

[0041] Step 4: Controlled curing and setting Remove excess liquid: Take out the saturated impregnated fabric and pass it through a pair of adjustable-gap rubber rollers, adjusting the pressure to remove excess impregnation liquid from the fabric surface and between layers.

[0042] Gradient drying: Lay the fabric flat in a forced-air drying oven. First, pre-dry at 60°C for 2 hours to allow most of the ethanol to evaporate slowly and prevent rapid pore closure; then raise the temperature to 80°C and continue drying for 6 hours until the fabric quality is constant (indicating complete removal of ethanol and residual PEG system).

[0043] Finished product acquisition: The sample was removed and allowed to cool naturally to room temperature, resulting in a finished flexible tactical protective skin that is dark gray in appearance, soft and thick to the touch, and has magnetic adsorption properties.

[0044] Example 3 This embodiment is basically the same as Embodiment 1, except that... 35 parts by weight of polyethylene glycol 200; 54 parts by weight of hydrophilic fumed silica; 10 parts by weight of carbonyl iron powder; 1 part by weight of polylysine.

[0045] Example 4 This embodiment is basically the same as Example 1, except that: 40 parts by weight of polyethylene glycol 200; 35 parts by weight of hydrophilic fumed silica; 20 parts by weight of carbonyl iron powder; and 5 parts by weight of polylysine.

[0046] Comparative Example 1 This comparative example is basically the same as Example 1, except that only carbonyl iron powder is added and polylysine is not added.

[0047] Comparative Example 2 This comparative example is basically the same as Example 1, except that after adding hard dispersed phase particles and electromagnetic loss type dispersed phase particles, only conventional stirring was performed, stirring at 1000 rpm for 30 minutes.

[0048] For the sample of Example 1, a total of 10 ballistic impact tests were carried out in the velocity range of 180m / s to 350m / s. The test conditions for each specimen included both penetration and non-penetration. The test results are shown in Table 1.

[0049] Table 1. Ballistic impact test results of Example 1

[0050] For the samples in the other embodiments and comparative examples, ballistic impact tests with an incident velocity of approximately 300 m / s were conducted according to the fragmentation simulation projectile test method in GJB 4300A-2012 "Safety Technical Performance Requirements for Military Bulletproof Vests". The results were compared with those in Example 1. At the same time, according to GJB 150.3A-2009 "Laboratory Environmental Test Methods for Military Equipment Part 3: High Temperature Test", each group of samples was placed in a high temperature environment of 70°C for 72 hours for heat aging durability test to verify the effect of polylysine (PLL) crosslinking structure on improving the stability of the system. The results are shown in Table 2.

[0051] Table 2 Comparison of ballistic impact test results and durability test results

[0052] For the sample in Example 1, absorption tests were conducted in the 8-12X frequency band. The experimental results are as follows: Figure 1 As shown.

[0053] The results above show that the flexible tactical protective skin of the present invention has a shear rate of less than 10 s⁻¹. -1 Under quasi-static conditions, it exhibits the characteristics of a flexible fabric; however, when subjected to a shear rate greater than 100 s⁻¹, it exhibits the characteristics of a flexible fabric. -1 Under dynamic impact, its energy storage modulus increases instantaneously by at least two orders of magnitude, and it exhibits good durability. Simultaneously, it achieves radar wave reflection loss (RL) of less than -10 dB in the X-band (8-12 GHz).

[0054] To achieve infrared stealth capabilities, a visible light-infrared camouflage coating can be sprayed onto the finished product, enabling integrated protection of individual soldier equipment through "soft and hard conversion" and "dual stealth," which will not be elaborated upon here.

Claims

1. A flexible tactical skin for individual soldiers, comprising a fibrous fabric matrix impregnated with a shear-thickening fluid, characterized in that, The shear-thickening fluid includes: Liquid dispersion medium; Hard dispersed phase particles; Electromagnetically depleted dispersed phase particles; and, Polylysine.

2. The individual flexible tactical skin according to claim 1, characterized in that, The liquid dispersion medium is polyethylene glycol or polypropylene glycol; the hard dispersed phase particles are fumed silica or monodisperse polymer microspheres; the fiber fabric matrix is ​​aramid fiber fabric, ultra-high molecular weight polyethylene fiber fabric, or poly(p-phenylenebenzodioxazole) fiber fabric.

3. The individual flexible tactical skin according to claim 1, characterized in that, The electromagnetic loss type dispersed phase particles are selected from one or more of the following: magnetic metal / alloy micro / nano powders, magnetic oxide particles, carbon-based conductive / magnetic materials, and two-dimensional transition metal carbon / nitrides.

4. The individual flexible tactical skin according to claim 1, characterized in that, The mass percentages of the components of the shear-thickening fluid are as follows: 30%-55% liquid dispersion medium, 35%-60% hard dispersed phase particles, 1%-20% electromagnetic loss type dispersed phase particles, and 1%-5% polylysine.

5. The individual flexible tactical skin according to claim 1, characterized in that, The mass percentages of the components of the shear-thickening fluid are as follows: liquid dispersion medium 43%, hard dispersed phase particles 40%, electromagnetic loss type dispersed phase particles 15%, and polylysine 2%.

6. The method for preparing a flexible tactical skin for individual soldiers as described in any one of claims 1 to 5, characterized in that, Includes the following steps: A liquid dispersion medium is placed in a container, polylysine is added to react, and then hard dispersed phase particles and electromagnetic loss type dispersed phase particles are added alternately in batches under mechanical stirring to form a mixed slurry. Subsequently, the mixed slurry is subjected to high shear dispersion treatment and high-energy ultrasonic crushing treatment to obtain a dispersion liquid. The dispersion liquid is then subjected to degassing treatment to obtain a shear thickening fluid precursor. The fiber fabric matrix is ​​impregnated with the shear-thickening fluid precursor to obtain the individual soldier flexible tactical skin.

7. The preparation method according to claim 6, characterized in that, The reaction conditions between the liquid dispersion medium and polylysine are: reaction at 25-40℃ for 12-24 hours under an inert atmosphere.

8. The preparation method according to claim 6, characterized in that, High-shear dispersion treatment specifically involves a rotation speed of 1000-5000 rpm and a time of 30-120 min; high-energy ultrasonic fragmentation treatment specifically involves an ultrasonic power of 200-1000 W and an ultrasonic time of 30-90 min.

9. The preparation method according to claim 6, characterized in that, The specific method for impregnating the fiber fabric matrix with a shear-thickening fluid precursor is as follows: First, the shear-thickening fluid precursor is diluted with a volatile solvent. Then, the fiber fabric matrix is ​​completely immersed in it until the fabric is saturated with the liquid. After that, it is taken out, dried and shaped to obtain the individual flexible tactical skin.

10. The use of any one of claims 1 to 5 in the preparation of individual soldier flexible tactical skin, tactical knee pads, tactical elbow pads, flexible exoskeleton armor and helmets.

Images