Preparation method and application of flexible ballistic protection knitted fabric

Abstract

The invention provides a preparation method and application of a flexible ballistic protection knitted fabric, and belongs to the field of materials. The preparation method comprises the following steps: enabling SiO2 nano-particles to form amido bonds through EDC-NHS coupling, and connecting the amido bonds with functional carboxyl groups of SiO2 nano-rods, so as to obtain hook-rod-shaped SiO2 composite nano-particles; and then, directly soaking the leased endless tows by utilizing a hook-rod-shaped silicon dioxide particle / absolute ethyl alcohol suspension, then carrying out drying treatment, and then plying and cabling to prepare the knitted fabric. According to the application, the hook-rod-shaped SiO2 composite nanoparticles are used, so that the friction effect between monofilaments is remarkably improved; the method comprises the following steps: leasing, soaking, plying and twisting endless tows, so that hook-rod-shaped SiO2 composite nanoparticles permeate into the fiber bundles as much as possible, and the use efficiency of the particles is improved; the processed endless tows are used for preparing the knitted structure, so that the endless tows are tightly stacked in a coil mode, yarn slippage is prevented, and the defense effect on small-size bullets is improved.

Description

Technical Field

[0001] The invention relates to the technical field of materials, and in particular to a preparation method and application of a flexible ballistic protection knitted fabric. Background Art

[0002] Compared with traditional pistol bullets, tungsten alloy projectiles are small in size, and it is difficult to capture high-speed flying projectiles using traditional flexible protective materials. In the prior art, the flexible braided structure is generally impregnated with a shear thickening liquid to enhance the bulletproof performance. The mechanism of action of the shear thickening liquid is to make the silica particles adhere to the surface of the filament bundle, increase the friction between the warp and weft yarns, constrain the slip characteristics of the fibers at the impact point, prevent the yarn from pulling out and opening windows, and enhance the overall synergistic effect of the braided structure.

[0003] For example, patent document CN 219829649 U discloses a knitted lightweight bulletproof vest, whose bulletproof layer immerses the Kevlar fiber layer in a shear thickening liquid to form a shear thickening liquid layer, thereby improving the bulletproof effect of the Kevlar fiber layer. Another example is patent document CN 215096142 U discloses a stab-proof and bulletproof fabric based on a shear thickening fluid and a preparation method thereof, the principle of which is to immerse the flocked fabric in a shear thickening fluid, and the vertically arranged functional short fibers are wrapped inside and around the shear thickening fluid, and then dried, cooled, and saturated with the flocking before a secondary coating or lamination is performed to obtain a finished fabric with certain mechanical properties. Another example is patent document CN202410454345.8, which prepares a silica particle suspension doped with aramid nanofibers, which can enhance the adhesion between the fluid and the aramid fabric and improve the structural stability.

[0004] However, the above patents are all for processing already formed plain fabrics, and there are the following problems: First, the nanoparticles have poor permeability into the filament bundles, and most of the particles will only stay on the surface of the filament bundles; second, the shear thickening liquid itself will cause a certain weight-increasing effect on the woven structure; third, the yarns in the plain weave structure are arranged relatively sparsely, and the projectiles can easily penetrate the target sample from the gaps between the yarns.

[0005] In view of this, it is necessary to design an improved method for preparing flexible ballistic protective knitted fabrics to solve the above problems. Summary of the invention

[0006] In view of the technical problems existing in the background technology, the present application provides a preparation method and application of a flexible ballistic protective knitted fabric, aiming to solve the technical problem that projectiles can easily penetrate the target sample.

[0007] In a first aspect, an embodiment of the present application provides a method for preparing a flexible ballistic protective knitted fabric, comprising the following steps:

[0008] S1, adding carboxyl-modified SiO2 nanorods, amino-modified spherical SiO2 nanoparticles, EDC, NHS and MES into PBS buffer, and magnetically stirring at 30°C for 0.5-2h to obtain hook-rod-shaped SiO2 composite nanoparticles;

[0009] S2, placing the hook-rod-shaped SiO2 composite nanoparticles obtained in step S1 into an oven for drying; stirring and mixing the hook-rod-shaped SiO2 composite nanoparticles with anhydrous ethanol, and ultrasonically dispersing the mixture to obtain a uniformly dispersed mixed solution;

[0010] S3, using a twisting device to twist the filament bundle, and immersing the twisted filament bundle into the suspension bath, and the filament bundle stays for 30-60 seconds; the suspension is the mixed solution obtained in step S2;

[0011] S4, drying the filament bundle obtained in step S3 at a temperature of 90° for 30 seconds;

[0012] The filament bundles are then resynthesized into one strand and twisted, with the twist controlled at 100 twists / m, to obtain filament bundles loaded with SiO2. The filament bundles loaded with SiO2 are used to prepare knitted fabrics, that is, flexible ballistic protective knitted fabrics are obtained.

[0013] In some embodiments, in step S1, the mass ratio of the carboxyl-modified SiO2 nanorods to the amino-modified spherical SiO2 nanoparticles is 1:1.5.

[0014] In some embodiments, in the mixed solution of step S2, the mass ratio of hook-rod-shaped SiO2 composite nanoparticles to anhydrous ethanol is 1:3.

[0015] In some embodiments, the preparation method of the carboxyl-modified SiO2 nanorods is: add SiO2 nanorods to DMF and ultrasonically disperse; then, add APTES and succinic anhydride to the solution and react with magnetic stirring for 2-6 hours; centrifuge and wash to obtain carboxyl-modified SiO2 nanorods.

[0016] In some embodiments, the preparation method of the amino-modified spherical SiO2 nanoparticles is: add spherical SiO2 nanoparticles and isopropanol into a flask, heat the reaction solution to 55°C and then add APTES, stir magnetically for 2-6 hours, centrifuge, and wash to obtain amino-modified spherical SiO2 nanoparticles.

[0017] In the technical solution of the embodiment of the present application, first, hook-rod-shaped SiO2 composite nanoparticles are obtained by connecting SiO2 nanoparticles to functionalized carboxyl groups of SiO2 nanorods through EDC-NHS coupling to form amide bonds; then, the twisted filament bundles are directly soaked in a hook-rod-shaped silica particle / anhydrous ethanol suspension, and then the filament bundles are combined and twisted for weaving.

[0018] The present application uses hook-rod-shaped SiO2 composite nanoparticles, so that the particles are attached to the surface of the nanorods to form a "hook-rod" shape, which significantly improves the friction between the monofilaments; by twisting the filament bundles, impregnating, plying and twisting, the hook-rod-shaped SiO2 composite nanoparticles can penetrate into the fiber bundle as much as possible, thereby improving the efficiency of particle use; and twisting can not only improve the bundling of the filaments, but also more tightly wrap the particles between the fibers, making it difficult for them to fall off the fiber surface.

[0019] In response to the problem of weight gain in traditional shear thickening fluid, this application does not add PEG, but directly mixes the particles with anhydrous ethanol. After the filament bundle leaves the solution, the wet filament bundle is dried in an oven to evaporate the anhydrous ethanol, remove the anhydrous ethanol, and minimize the weight gain. The particles remaining on the fiber surface no longer have fluidity and can maintain the initial distribution state no matter how long they are left standing.

[0020] The knitted structure is formed by stacking and nesting coils, and the fibers are tightly bonded to each other. For small-sized projectiles, it can effectively limit fiber slippage, prolong the contact time between the projectile and the target, and absorb the kinetic energy of the projectile; at the same time, the hook-shaped SiO2 composite nanoparticles in this application remain on the fiber surface to increase the roughness of the fiber. This application uses treated filament bundles to prepare a knitted structure, so that the filament bundles are tightly stacked in the form of coils, preventing yarn slippage and improving the defense effect against small-sized projectiles.

[0021] In a second aspect, an embodiment of the present application provides an application of a flexible ballistic protective knitted fabric, which can be used as an umbrella cloth material for a foldable portable bulletproof umbrella.

[0022] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings used in the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 This is a schematic diagram of the process of filament processing and fabric preparation in the embodiment of the present application;

[0025] Figure 2 The microscopic morphology of the filament bundle before treatment and the fabric after treatment in Example 1; (a) SEM image of the filament bundle before treatment, (b) SEM image of the filament bundle after treatment Figure 1 , (c) FESEM image of the filament bundle after treatment, (d) SEM image of the filament bundle after treatment Figure 2 .

[0026] Figure 3 This is a device for testing the ballistic performance of fabrics used in this application.

[0027] Figure 4 High-speed photography of a projectile penetrating the flexible ballistic protective knitted fabrics prepared in Example 1 and Comparative Examples 1-6. DETAILED DESCRIPTION

[0028] The following embodiments of the technical solution of the present application will be described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0030] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0031] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0032] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0033] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0034] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0035] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0036] The invention is mainly used to resist the fragments of the 09-type 18.4mm lethal shotgun. The 09-type 18.4mm military shotgun bullet has a full bullet length of 65mm, a full bullet weight of 44g, an initial velocity of 420m / s, and contains 14 tungsten alloy projectiles with a diameter of 5.3mm and a weight of 1.4g. Compared with traditional pistol bullets, tungsten alloy projectiles are small in size, so it is difficult to capture high-speed flying projectiles using traditional flexible protective materials.

[0037] Taking the woven plain weave structure as an example, the advantage of plain weave fabric is its high softness, which can meet the needs of repeated folding and folding of bulletproof umbrellas during use. However, since woven fabrics are made by interweaving warp and weft yarns, their structure is relatively loose, and the fibers at the impact point are prone to slip during the contact between the projectile and the target, resulting in "window opening" and "pulling" effects, and the projectile can easily penetrate the fabric target surface.

[0038] Take the weftless fabric as an example, weftless fabric (also called unidirectional fabric or UD fabric). In the weftless fabric, the same layer of monofilaments is arranged straight in one direction, which can maximize the strength and stiffness of the fiber, and can accelerate the propagation speed of transverse waves and longitudinal waves inside the monofilaments, and efficiently disperse the impact energy. The weftless fabric is usually made of multiple layers of fiber mesh orthogonally laid in a (0° / 90°) manner, and reinforced with adhesives or resin materials (such as water-based polyurethane or thermoplastic resin). Because the monofilaments are fixed by adhesive materials, under the high-speed impact of projectiles, the fibers are not easily pulled out or formed into gaps by the projectile like woven fabrics, and the overall structural stability and anti-ballistic performance of the material have been greatly improved. It is precisely because the sliding characteristics of the fibers are weakened by the adhesive that the stiffness of the weftless fabric is very large, which is not conducive to the opening and closing of the bulletproof umbrella during use. In addition, during the contact between the projectile and the target, the filaments are loaded by the projectile, which makes it easy to debond, and cannot exert its excellent mechanical properties, resulting in the projectile easily penetrating the target sample.

[0039] In addition, in the existing stab-proof and bullet-proof fabrics based on shear thickening fluid, on the one hand, the special rheological properties of the shear thickening fluid are needed to achieve synergistic enhancement of the protective performance of the high-performance fiber materials to ensure that the protective system can show a local hardening effect under high-speed impact. On the other hand, the presence of the shear thickening fluid itself will cause a certain weight-increasing effect on the woven structure. Specifically, the PEG remaining on the fiber surface will increase the weight of the fabric, and the dispersion state of the nanoparticles will change after long-term storage.

[0040] In order to solve the technical problem that the projectile easily penetrates the target sample, the present application provides a method for preparing a flexible ballistic protective knitted fabric, comprising the following steps:

[0041] S1, adding carboxyl-modified SiO2 nanorods, amino-modified spherical SiO2 nanoparticles, EDC, NHS and MES into PBS buffer, and magnetically stirring at 30°C for 0.5-2h, so that the SiO2 nanoparticles are connected to the functionalized carboxyl groups of the SiO2 nanorods through amide bonds formed by EDC-NHS coupling, to obtain hook-rod-shaped SiO2 composite nanoparticles;

[0042] The mass ratio of carboxyl-modified SiO2 nanorods to amino-modified spherical SiO2 nanoparticles is 1:1.5.

[0043] Specifically, the preparation method of carboxyl-modified SiO2 nanorods is as follows: add SiO2 nanorods into DMF and disperse them ultrasonically; then, add APTES and succinic anhydride into the solution and react with magnetic stirring for 2-6 hours; centrifuge and wash to obtain carboxyl-modified SiO2 nanorods.

[0044] The preparation method of amino-modified spherical SiO2 nanoparticles is as follows: spherical SiO2 nanoparticles and isopropanol are added into a flask, the reaction solution is heated to 55°C and then APTES is added, the reaction is magnetically stirred for 2-6 hours, and then centrifuged and washed to obtain amino-modified spherical SiO2 nanoparticles.

[0045] S2, placing the hook-rod-shaped SiO2 composite nanoparticles obtained in step S1 in a 60-80° C. oven for drying; stirring and mixing the hook-rod-shaped SiO2 composite nanoparticles with anhydrous ethanol, and ultrasonically dispersing the mixture to obtain a uniformly dispersed mixed solution;

[0046] In the mixed solution, the mass ratio of hook-rod-shaped SiO2 composite nanoparticles to anhydrous ethanol is 1:3.

[0047] S3, using a twisting device to twist the filament bundle, and immersing the twisted filament bundle into the suspension bath, and the filament bundle stays for 30 seconds; wherein the suspension is the mixed solution obtained in step S2;

[0048] S4, drying the filament bundle obtained in step S3 at a temperature of 90° for 30 seconds;

[0049] The filament bundles are then resynthesized into one strand and twisted, with the twist controlled at 100 twists / m, to obtain filament bundles loaded with SiO2. Knitted fabrics are prepared using the filament bundles loaded with SiO2, thereby obtaining flexible ballistic protective knitted fabrics.

[0050] In the embodiments of the present application, first, hook-rod-shaped SiO2 composite nanoparticles are obtained by connecting SiO2 nanoparticles to functionalized carboxyl groups of SiO2 nanorods through EDC-NHS coupling to form amide bonds; then, the twisted filament bundles are directly soaked in a hook-rod-shaped silica particle / anhydrous ethanol suspension, and then the filament bundles are combined and twisted for weaving.

[0051] The present application uses hook-rod-shaped SiO2 composite nanoparticles, so that the particles are attached to the surface of the nanorods to form a "hook-rod" shape, which significantly improves the friction between the monofilaments; by twisting the filament bundles, impregnating, plying and twisting, the hook-rod-shaped SiO2 composite nanoparticles can penetrate into the fiber bundle as much as possible, thereby improving the efficiency of particle use; and twisting can not only improve the bundling of the filaments, but also more tightly wrap the particles between the fibers, making it difficult for them to fall off the fiber surface.

[0052] In response to the problem of weight gain in traditional shear thickening fluid, this application does not add PEG, but directly mixes the particles with anhydrous ethanol. After the filament bundle leaves the solution, the wet filament bundle is dried in an oven to evaporate the anhydrous ethanol, remove the anhydrous ethanol, and minimize the weight gain. The particles remaining on the fiber surface no longer have fluidity and can maintain the initial distribution state no matter how long they are left standing.

[0053] The knitted structure is formed by stacking and nesting coils, and the fibers are tightly bonded to each other. For small-sized projectiles, it can effectively limit fiber slippage, prolong the contact time between the projectile and the target, and absorb the kinetic energy of the projectile; at the same time, the hook-shaped SiO2 composite nanoparticles in this application remain on the fiber surface to increase the roughness of the fiber. This application uses treated filament bundles to prepare a knitted structure, so that the filament bundles are tightly stacked in the form of coils, preventing yarn slippage and improving the defense effect against small-sized projectiles.

[0054] Some specific embodiments are listed below. It should be noted that the embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used without specifying the manufacturer are all conventional products that can be obtained commercially.

[0055] 1. Preparation method

[0056] Example 1

[0057] This embodiment provides a method for preparing a flexible ballistic protective knitted fabric, comprising the following steps:

[0058] S11, Preparation of SiO2 nanorods by reverse microemulsion method

[0059] First, a certain amount of sodium citrate was weighed and placed in a 25 mL volumetric flask, and water was added to make up to the volume to prepare a 0.18 M sodium citrate solution; a certain proportion of PVP and n-pentanol were added to the conical flask, and ultrasonic dispersion was performed until the PVP was completely dissolved; after the dissolution was completed, deionized water, sodium citrate solution, anhydrous ethanol, and ammonia solution were added to the solution in sequence, and the solution was vigorously stirred by magnetic force; TEOS was added to the reaction solution, and the solution was shaken evenly by hand, and was placed in an oven at 40°C for 4 hours to react; after the reaction was completed, centrifuged at 5000 rpm for 10 minutes, the clear liquid was removed, anhydrous ethanol was added for dispersion and washing three times, and centrifuged at 3000 rpm for 8 minutes,

[0060] S12, Preparation of Spherical SiO2 Nanoparticles

[0061] First, weigh a certain amount of anhydrous ethanol and deionized water and add them to a 150mL conical flask, stir evenly with a glass rod, add a 28% ammonia solution, and stir with an electromagnetic stirrer at 40°C for half an hour; add tetraethyl orthosilicate dropwise, and keep the magnetic stirring at 45°C for 2 hours; after the reaction is completed, centrifuge the mixture from the liquid sample. The reaction product is centrifuged at a speed of 8000 rpm for 3 minutes, and the obtained precipitate is washed with anhydrous ethanol three times, and centrifuged at the same centrifugal speed and time; the final precipitate is dispersed in anhydrous ethanol.

[0062] S13, Carboxylation modification of SiO2 nanorods

[0063] A certain amount of SiO2 nanorods and DMF (60 mL) were weighed and evenly dispersed by ultrasound; a certain proportion of APTES and succinic anhydride were added to the solution and magnetically stirred at 60°C for 4 hours; the solution was collected by centrifugation and washed alternately with ethanol and deionized water.

[0064] S14, Amination modification of spherical SiO2 nanoparticles

[0065] The collected spherical SiO2 nanoparticles and isopropanol (60 mL) were added to a 100 mL flask; the reaction solution was heated to 55°C and APTES was added. The reaction was stirred magnetically for 6 hours and then centrifuged and washed three times with deionized water.

[0066] S15, Preparation of hook-rod-shaped SiO2 composite nanoparticles

[0067] In PBS buffer (60 mL), carboxyl-modified SiO2 nanorods and amino-modified spherical SiO2 nanoparticles were added in a ratio of 1:1.5, and EDC, NHS and MES were continued to be added. The mixture was magnetically stirred at 30°C for half an hour to form amide bonds between the SiO2 nanoparticles and the functionalized carboxyl groups of the SiO2 nanorods through EDC-NHS coupling. Composite nanoparticles were obtained by centrifugal washing to obtain hook-rod-shaped SiO2 composite nanoparticles.

[0068] S2, placing the hook-rod-shaped SiO2 composite nanoparticles obtained in step S15 in a 60°C oven for drying for 12 hours to ensure that the particles are in a dry state during the preparation process to prevent the particles from absorbing water and causing errors; weighing the hook-rod-shaped SiO2 composite nanoparticles and the dispersant anhydrous ethanol in a mass ratio of 1:3, and stirring the anhydrous ethanol and the hook-rod-shaped SiO2 nanoparticles, and then using ultrasonic dispersion treatment to disperse the particles as evenly as possible in the anhydrous ethanol to obtain a uniformly dispersed mixed solution;

[0069] S3, using a twisting device to twist the filament bundle to further refine the filament bundle; then, the twisted filament bundle is immersed in the suspension bath, and the filament bundle stays for 30 seconds; wherein the suspension is the mixed solution obtained in step S2;

[0070] S4, drying the filament bundle obtained in step S3 at a temperature of 90° for 30 seconds;

[0071] The filament bundles are then resynthesized into one strand and twisted, with the twist controlled at 100 twists / m, to obtain filament bundles loaded with SiO2. The filament bundles loaded with SiO2 are used to prepare knitted fabrics on a circular knitting machine, thereby obtaining flexible ballistic protective knitted fabrics.

[0072] Specifically, Figure 1 As shown, the filament bundle on the yarn tube 1 is divided into two strands by a twisting rod 2, and the two filament bundles are respectively immersed in the suspension bath 3, and the filament bundle stays for 30 seconds. The filament bundle is squeezed by an extrusion roller 4 and dried in an oven 5 at a temperature of 90° for 30 seconds. After drying, the filament bundle is collected by a winding device 6 and twisted by a doubling machine 7 with the twist controlled at 100 twists / m to obtain a filament bundle loaded with SiO2. Finally, the filament bundle loaded with SiO2 is used to prepare a knitted fabric on a circular machine 8, thereby obtaining a flexible ballistic protective knitted fabric.

[0073] See also Figure 2 As shown, before treatment, the surface of the filament bundle is smooth. Figure 2 As shown in (a), after treatment, the surface of the filament bundle is loaded with hook-rod-shaped SiO2 composite nanoparticles.

[0074] Comparative Example 1

[0075] Comparative Example 1 provides a method for preparing a flexible ballistic protective knitted fabric. Compared with Example 1, the difference is that no yarn processing is performed, and the knitted fabric is prepared by directly bundled filaments on a circular knitting machine.

[0076] Comparative Example 2

[0077] Comparative Example 2 provides a method for preparing a flexible ballistic protective knitted fabric. Compared with Example 1, the difference is that the woven knitted fabric is directly immersed in the mixed solution obtained in step S2 and then dried for use. The rest is roughly the same as Example 1 and will not be repeated here.

[0078] Comparative Example 3

[0079] Comparative Example 3 provides a method for preparing a flexible ballistic protective woven fabric. Compared with Example 1, the difference is that the woven fabric is directly immersed in the mixed solution obtained in step S2 and then dried for use. The rest is roughly the same as Example 1 and will not be repeated here.

[0080] Comparative Example 4

[0081] Comparative Example 4 provides a method for preparing a flexible ballistic protective knitted fabric. Compared with Example 1, the difference is that the filament bundles are not twisted and stranded, but the filament bundles are directly immersed in the mixed solution obtained in step S2. The rest is roughly the same as Example 1 and will not be repeated here.

[0082] Comparative Example 5

[0083] Comparative Example 5 provides a method for preparing a flexible ballistic protective knitted fabric. Compared with Example 1, the difference is that hook-rod-shaped SiO2 composite nanoparticles are not used, and the SiO2 nanorods prepared in step S11 are directly used, that is, the hook-rod-shaped SiO2 composite nanoparticles in step S2 are replaced by the SiO2 nanorods prepared in step S11. The rest is roughly the same as Example 1 and will not be repeated here.

[0084] Comparative Example 6

[0085] Comparative Example 6 provides a method for preparing a flexible ballistic protective knitted fabric. Compared with Example 1, the difference is that hook-rod-shaped SiO2 composite nanoparticles are not used, and the spherical SiO2 nanoparticles prepared in step S12 are directly used, that is, the hook-rod-shaped SiO2 composite nanoparticles in step S2 are replaced by the spherical SiO2 nanoparticles prepared in step S12. The rest is roughly the same as Example 1 and will not be repeated here.

[0086] 2. Test Method

[0087] Test method for ballistic performance of modified knitted fabrics

[0088] Experimental setup Figure 3 As shown:

[0089] The laboratory temperature is 24 degrees and the humidity is 20%. A first-stage light gas gun is used for ballistic experiments, and the barrel has no rifling. The inner diameter of the launch tube is 14 mm and the length is 1.8 meters. A spherical bullet with a diameter of 8 mm and a mass of 2.11 grams is used. Since the inner diameter of the launch tube is larger than the diameter of the projectile, a bullet drag made of polyethylene is used to protect the inner wall of the launch tube and ensure the stability of the projectile launch trajectory. The bullet drag is 10 mm high and 14 mm in diameter. A bowl-shaped depression is formed on the impact side and bonded to the projectile. High-pressure nitrogen is used to pressurize the bullet drag and the projectile in the barrel to accelerate the impact speed to control the impact speed at 100-300 m / s, and high-pressure helium is used to pressurize the impact speed to between 300 m / s and 450 m / s. Two sets of infrared velocimeters are used to measure the impact speed and residual speed of the projectile respectively. The ballistic performance of the sample target is obtained in the following way:

[0090]

[0091] Among them, ΔE is the kinetic energy lost by the projectile during penetration, m is the mass of the projectile, and v1 and v2 are the impact velocity and residual velocity of the projectile, respectively. In this study, the kinetic energy loss caused by air resistance during the flight of the projectile was not considered. A projectile recovery device was placed behind the second set of velocimeters, with vulcanized rubber placed inside to act as a buffer.

[0092] The ballistic protection performance of the flexible ballistic protective knitted fabrics prepared in Example 1 and Comparative Examples 1-6 was tested. Figure 4 As shown, the test results are shown in the following table. It can be seen that the energy absorption effect presented by Example 1 is much better than that of Comparative Examples 1-6.

[0093]

[0094]

[0095] Comparative Example 1 Incident speed (m / s) Ejection speed (m / s) Energy absorption (J) 1 286.5 228.0 31.8 2 261.7 0.0 72.3 3 292.0 258.2 19.6 4 298.2 269.6 17.1 5 303.5 280.4 14.2 6 334.4 318.9 10.7 7 341.1 323.2 12.5 8 347.6 336.6 8.0 9 393.0 385.1 6.5 average 317.6 266.7 21.4

[0096]

[0097]

[0098] Comparative Example 3 Incident speed (m / s) Ejection speed (m / s) Energy absorption (J) 1 148.3 0.0 23.2 2 155.1 0.0 25.4 3 184.1 131.1 17.6 4 229.7 199.5 13.7 5 265.6 243.6 11.8 6 278.3 263.2 8.6 7 288.9 259.0 17.3 8 337.3 319.2 12.5 9 347.1 330.6 11.8 average 248.3 194.0 15.8

[0099] Comparative Example 4 Incident speed (m / s) Ejection speed (m / s) Energy absorption (J) 1 280.5 0 83.0 2 278.4 0 81.8 3 279.3 0 82.3 4 306.5 232.7 42.0 5 308.2 233.1 42.9 6 313.3 227.7 48.9 7 319.4 223 55.2 8 328.6 204.9 69.6 9 344.6 270.2 48.3 average 306.5 154.6 61.5

[0100] Comparative Example 5 Incident speed (m / s) Ejection speed (m / s) Energy absorption (J) 1 267 21.7 74.7 2 269.4 42.8 74.6 3 271.3 146.5 55.0 4 277.5 155.1 55.9 5 282.4 164.7 55.5 6 287.1 212.9 39.1 7 319 268.6 31.2 8 337.1 305.6 21.4 9 364.3 330.4 24.8 average 297.2 183.1 48.0

[0101] Comparative Example 6 Incident speed (m / s) Ejection speed (m / s) Energy absorption (J) 1 263.4 0.0 73.2 2 265.0 183.9 38.4 3 266.0 175.5 42.2 4 270.8 0.0 77.4 5 279.5 219.6 31.5 6 319.8 260.2 36.4 7 328.1 300.3 18.4 8 346.0 312.3 23.4 9 377.8 350.0 21.4 average 301.8 200.2 40.3

[0102] According to the above experimental data, the sample prepared in Example 1 has the best ballistic protection effect, with a ballistic limit of 289m / s and an average energy absorption of 71.8J. The worst performance is in Comparative Example 3, whose average energy absorption is only 22% of that in Example 1. This shows that the structural effect of the woven fabric and the interweaving mode of the warp and weft yarns greatly limit its ballistic protection effect. The average energy absorption of Comparative Example 1 is 21.4J, which is 29.8% of that in Example 1, indicating that the use of "hook-and-stick" shaped nanoparticles can play a synergistic role in knitted fabrics and greatly improve the energy absorption effect of the knitted structure.

[0103] The average energy absorption of Comparative Example 2 is 36.6 J, which is 50.09% of that of Example 1. This means that directly soaking the finished knitted structure can play a certain reinforcing role, but due to the poor permeability of the particles, the effect is not as strong as weaving with treated yarn.

[0104] The average energy absorption of Comparative Example 4 is 61.5 J, which is 85.6% of that of Example 1, which means that without the twisting process, the penetration effect of the nanoparticles is not as good as that with the twisting process, which reflects the necessity of the twisting process of the filament bundles before impregnation.

[0105] The average energy absorption of Comparative Examples 5 and 6 are 48 J and 40.3 J, respectively, which are lower than that of Example 1, which means that the synergistic effect of simple nanoparticles and nanorods on the knitted fabric structure is not as good as that of hook-rod-shaped nanoparticles.

[0106] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for preparing a flexible ballistic protective knitted fabric, characterized in that: The steps include: S1, adding carboxyl-modified SiO2 nanorods, amino-modified spherical SiO2 nanoparticles, EDC, NHS and MES into PBS buffer, and magnetically stirring at 30°C for 0.5-2h to obtain hook-rod-shaped SiO2 composite nanoparticles; S2, placing the hook-rod-shaped SiO2 composite nanoparticles obtained in step S1 into an oven for drying; stirring and mixing the hook-rod-shaped SiO2 composite nanoparticles with anhydrous ethanol, and ultrasonically dispersing the mixture to obtain a uniformly dispersed mixed solution; S3, using a twisting device to twist the filament bundle, and immersing the twisted filament bundle into the suspension bath, and the filament bundle stays for 30-60 seconds; the suspension is the mixed solution obtained in step S2; S4, drying the filament bundle obtained in step S3 at a temperature of 90° for 30 seconds; The filament bundles are then resynthesized into one strand and twisted, with the twist controlled at 100 twists / m, to obtain filament bundles loaded with SiO2. The filament bundles loaded with SiO2 are used to prepare knitted fabrics, that is, flexible ballistic protective knitted fabrics are obtained.

2. The method for preparing the flexible ballistic protective knitted fabric according to claim 1, characterized in that: In step S1, the mass ratio of the carboxyl-modified SiO2 nanorods to the amino-modified spherical SiO2 nanoparticles is 1:1.

5.

3. The method for preparing the flexible ballistic protective knitted fabric according to claim 1, characterized in that: In the mixed solution of step S2, the mass ratio of hook-rod-shaped SiO2 composite nanoparticles to anhydrous ethanol is 1:

3.

4. The method for preparing the flexible ballistic protective knitted fabric according to claim 1, characterized in that: The preparation method of the carboxyl modified SiO2 nanorods is as follows: adding the SiO2 nanorods into DMF and dispersing by ultrasonication; Then, APTES and succinic anhydride are added to the solution, and the solution is reacted for 2-6 hours by magnetic stirring; the solution is centrifuged and washed to obtain carboxyl-modified SiO2 nanorods.

5. The method for preparing the flexible ballistic protective knitted fabric according to claim 1, characterized in that: The preparation method of the amino-modified spherical SiO2 nanoparticles is as follows: adding spherical SiO2 nanoparticles and isopropanol into a flask, heating the reaction solution to 55°C and then adding APTES, stirring the reaction magnetically for 2-6 hours, centrifuging, and washing to obtain amino-modified spherical SiO2 nanoparticles.

6. Application of a flexible ballistic protective knitted fabric, characterized in that: The flexible ballistic protection knitted fabric is prepared by the preparation method described in any one of claims 1 to 5, and the flexible ballistic protection knitted fabric can be used as an umbrella cloth material for a foldable portable bulletproof umbrella.

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