A flexible, cut-protective fabric and a method of making the same

Abstract

The present application relates to a kind of flexible anti-cutting fabric and its preparation method, belong to the technical field of protective material.The fabric includes outer layer and inner layer: outer layer is four-order density gradient knitted structure, area density decreases from outside to inside step by step, in turn by base weft, tuck, tuck-cotton complex organization and tuck organization constitute;Inner layer is three-dimensional spacing structure, including top layer, bottom layer and connecting system, connecting system is by double helix elastic connecting yarn with the way of tuck alternately connecting top layer and bottom layer.Outside layer and inner layer are integrally compounded by loop stringing. Preparation method uses double needle bar computer flat knitting machine or warp knitting machine, realizes by the steps of weaving outer layer, weaving inner layer and compounding, circulation and post finishing step.The present application disperses puncture energy by gradient density outer layer, three-dimensional spacing inner layer absorbs impact, only 1-2 layers can meet the 24J protection requirement of public security department GA68-2024 standard, simultaneously has flexibility, air permeability and comfort.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of anti-cutting and anti-piercing fabric, in particular to a flexible anti-cutting and anti-piercing fabric and a preparation method thereof. BACKGROUND

[0002] High-performance flexible anti-cutting and anti-piercing fabric is an important research direction in the field of personal protective equipment. Traditional anti-cutting and anti-piercing fabric usually adopts the design idea of "stacking multiple layers of uniform density materials", relying on simply increasing the thickness to achieve protection, resulting in heavy and stiff overall fabric, poor air and moisture permeability, and seriously affecting the wearing comfort, thereby limiting its further application.

[0003] There are multi-layer anti-cutting and anti-piercing structures integrated by full-fashioned knitting process in the prior art, which improve the interlayer bonding force and integrity of the fabric to some extent, and try to enhance the protective performance by introducing functional treated yarns. However, there are still some deficiencies in the design of such structures: first, there is a lack of systematic energy dissipation gradient design between each functional layer, and the protection mechanism mainly relies on the superposition of homogeneous materials and single friction energy dissipation mode, and the energy dissipation path is relatively single. Second, due to the lack of an outer layer structure with high density and high stiffness to preferentially bear and deflect the load, the inner layer buffer structure is easy to bear too concentrated stress. Third, some functional treated materials may have the problem of insufficient durability, and the performance may decrease after multiple uses or washes, and at the same time, the original flexibility of the fabric may be sacrificed.

[0004] Therefore, there is still a need to develop an integrated fabric structure that achieves a good balance between anti-cutting and anti-piercing performance, durability, flexibility, and wearing comfort. SUMMARY

[0005] The purpose of the present application is to overcome the deficiencies in the prior art and provide a flexible anti-cutting and anti-piercing fabric and a preparation method thereof.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present application is:

[0007] The first aspect is to provide a flexible anti-cut fabric, comprising an outer layer and an inner layer, the outer layer is a four-order density gradient knitted structure, which comprises first, second, third and fourth orders from outside to inside, the area density of the four-order density gradient knitted structure decreases step by step from outside to inside, and the transition zone between adjacent two orders is seamlessly connected by knitting; the area density of the second order is reduced by 5%-30% compared with the first order, the area density of the third order is reduced by 5%-30% compared with the second order, and the area density of the fourth order is reduced by 5%-30% compared with the third order; if the decreasing rate is too low (<5%), the gradient is not obvious, and the stress dispersion effect is limited; if the decreasing rate is too high (>30%), it may cause sudden change of structural stiffness, causing uneven stress concentration and diffusion, which is not conducive to smooth transition of energy; wherein the first order is weft insertion stitch, the second order is tuck stitch, the third order is tuck-and-plain composite stitch, and the fourth order is tuck stitch; the outer layer is knitted by first yarn, and the yarn count of the first yarn is 100-1000D, and the yarn strength is ≥20 cn / dtex;

[0008] The inner layer is a three-dimensional spacing structure, comprising a top layer, a bottom layer and a connecting system, the top layer is knitted by second yarn, the second yarn is twisted with the first yarn, the bottom layer is woven by third yarn, the connecting system is composed of two yarns with different elasticity by spiral twisting, and is connected between the top layer and the bottom layer in the form of tuck stitch on the front and back needle beds, forming a three-dimensional spacing layer for buffering impact; the third yarn is selected from one or more of cotton, modal, lyocell and bamboo fiber;

[0009] The fourth order of the outer layer and the top layer of the inner layer are integrally formed by knitting with loops interlocking each other.

[0010] Further, the first yarn is one or more of polyethylene, aramid, PBO filament, nylon, polyester and metal wire.

[0011] Further, the mass ratio of the splicing of the spandex and the first yarn is 3:97-15:85, and the twist is 400 twists / m-800 twists / m; if the proportion of spandex is too low (less than 3%), the yarn elasticity is insufficient, and the inner layer buffering effect is poor; if the proportion of spandex is too high (more than 15%), the yarn strength decreases, affecting the interlayer bonding force and overall protection performance; the twist of the second yarn is controlled between 400-800 twists / m, to ensure the stability of the splicing structure and the good flexibility of the yarn.

[0012] Further, the two different elastic yarns are both elastic yarns, including a high-elasticity yarn and a medium-elasticity yarn; the breaking elongation of the high-elasticity yarn is ≥ 50%, and the breaking elongation of the medium-elasticity yarn is 20%~40%. By constructing such a "pure elasticity" system, under impact load, the high-elasticity yarn first undergoes large deformation to absorb most of the energy, and the medium-elasticity yarn provides initial stiffness and recovery force to control the deformation process and prevent the high-elasticity yarn from being plastically damaged or broken due to excessive stretching. The two are coordinated to achieve the unity of fast response, high energy absorption, controllable rebound and excellent durability.

[0013] Further, the flexible anti-puncture fabric has a grammage of 280g / m²~1000g / m².

[0014] The second aspect is to provide a preparation method of the above-mentioned flexible anti-puncture fabric, which is integrally knitted by using a double-needle bed multi-axial warp knitting machine, wherein the warp knitting machine is equipped with a multi-axial laying device and a plurality of guide bars, the guide bars include a first group of guide bars for knitting an outer layer, a second group of guide bars for knitting an inner layer, and a spacer guide bar for forming a connection system; the preparation method comprises the following steps:

[0015] S1. Yarn configuration and system preparation: configure the yarns to the corresponding guide bars and set the knitting program; that is, configure the first yarn for knitting the outer layer structure to the first group of guide bars; configure the second yarn for knitting the top layer of the inner layer to a front needle bed guide bar in the second group of guide bars; configure the third yarn for knitting the bottom layer of the inner layer to a back needle bed guide bar in the second group of guide bars; and configure the double helix elastic connection yarn to the spacer guide bar;

[0016] S2. Integrally knitting the outer layer and the inner layer structure: start the warp knitting machine, and under program control, the multi-axial laying device and each guide bar work cooperatively to synchronously perform the following knitting actions:

[0017] (a) Knitting the four-order density gradient structure of the outer layer

[0018] The first yarn is laid by a multi-axial laying device while being looped on the front needle bed by the first group of guide bars to form a knitted structure with stepwise decreasing surface density from outside to inside; a transition area is arranged between each step, and the guide bars of the next step are involved in work before the previous step is completed, so that the yarns of adjacent two steps naturally interweave and interlace with each other in the knitting process to form an integrated connection structure; the four-step density gradient structure sequentially includes: a first-step super-dense laid-in stitch formed by simultaneously feeding two first yarns in parallel without twisting in the same course; a second-step high-density tuck stitch formed on the inner side of the first step by adjusting the laid-in yarn density and tuck structure; a third-step medium-density tuck-and-flat composite stitch formed by further adjusting the yarn arrangement density and stitch structure; a fourth-step low-density tuck stitch formed by increasing the spacing between weft yarns; and the decreasing rate of the surface density of each step is 5% to 30%;

[0019] (b) knitting an inner layer three-dimensional spacing structure and realizing layer composite: while knitting the fourth-step structure of the outer layer, the second yarn is fed by the front needle bed guide bar to continue knitting on the front needle bed to form the top layer of the inner layer; the third yarn is fed by the back needle bed guide bar to knit the bottom layer of the inner layer on the back needle bed; the double-helix elastic connecting yarn is fed by the spacing guide bar, and the double-helix elastic connecting yarn is alternately tuck-knitted on the front needle bed and the back needle bed in a 'V' shape or 'W' shape path to connect the top layer and the bottom layer to form the connecting system and the three-dimensional spacing structure; wherein the fourth step of the outer layer and the top layer of the inner layer are integrally formed by loop interlacing knitting;

[0020] S3. Cycle: the whole machine guide bar system synchronously and coordinately operates, and the knitting process of step S2 is repeated until the fabric base fabric with the required length is knitted;

[0021] S4. Post-processing: the fabric base fabric obtained in step S3 is introduced into a heat setting machine at a tension of 5-10 N / m, and is subjected to heat treatment at a temperature of 60-105°C, and then is cooled and set to obtain a flexible anti-cutting fabric with smooth surface and stable size.

[0022] Further, in step S1, when the first-step super-dense laid-in stitch is knitted, a "double-filament parallel laid-in" method is adopted, that is, two first yarns are simultaneously fed in parallel without twisting in the same knitting course by the laying device.

[0023] Further, in step S4, the heat setting is immediately followed by entering a cooling zone for rapid cooling and setting at a cooling rate of not less than 10-20°C / min to below 40°C.

[0024] Compared with the prior art, the above technical scheme has the following technical effects:

[0025] The application breaks through the traditional protective material homogeneous layering mindset and constructs an integrated composite structure combining a four-step gradient density protective outer layer with "outer dense and inner sparse" and a three-dimensional spaced buffer inner layer with "stretching-compression" dual-mode energy absorption. The penetration of sharp objects (such as knives) is a dynamic energy concentration process. The four-step gradient density structure of the outer layer converts the concentrated penetration energy into dispersed stress through physical design of structural gradient and dissipates it step by step. Compared with conventional plain woven fabric and plain knit structure, the fiber aggregation degree at the knife tip is improved, and the resistance of the knife is stronger.

[0026] Since the overall structure is formed based on the knitting process, the fabric of the application has good inherent flexibility and ductility. The continuous air channels formed by the three-dimensional spacer layer help to improve the air and moisture permeability, and the inner layer is made of soft and skin-friendly materials, which significantly improves the wearing comfort while ensuring the protection performance, and is suitable for long-term dressing needs.

[0027] The integrated weaving of the outer layer and the inner layer is achieved by knitting programming, and the layers are connected through loop stringing, which enhances the interface bonding strength and avoids the problems of rigidity, easy delamination and air permeability reduction caused by traditional lamination or coating process, while also helps to improve production efficiency and product consistency. DETAILED DESCRIPTION

[0028] The application will be further described below in conjunction with specific embodiments, but not as a limitation of the application. It should be noted that the embodiments in the application and the features in the embodiments can be combined with each other without conflict.

[0029] Example 1

[0030] This embodiment provides a flexible anti-cut and anti-puncture fabric with a face density of 720 g / m², which realizes excellent anti-cut and anti-puncture performance, flexibility and comfort through the integrated design of gradient density structure and three-dimensional spacer layer. The fabric structure includes an outer layer and an inner layer, wherein the outer layer adopts a four-step density gradient structure to resist cutting and penetration, and the inner layer adopts a three-dimensional spacer structure to absorb impact energy and provide air permeability. The design parameters, preparation process and performance of the fabric are described in detail below.

[0031] 1. Fabric structure design

[0032] (1) Outer layer

[0033] The outer layer is composed of 800D high-strength and high-modulus polyethylene filaments (first yarn) (strength 32 cN / dtex), which adopts a four-step density gradient structure, with the density decreasing step by step from outside to inside, forming a gradient impedance effect to disperse and dissipate impact energy. The specific parameters of the four-step structure are as follows:

[0034] 1) First step (super-dense weft-knit structure):

[0035] Process: Using the "double-silk parallel laying-in" process, two 800D high-strength and high-modulus polyethylene filaments (first yarns) are simultaneously fed in parallel without twisting by the laying-in device in the same course and laid into the same structure layer of the fabric guided by the first group of guide bars.

[0036] Advantages: A single laying-in operation can introduce double the amount of cut-resistant yarns, greatly improving the knitting efficiency and the construction speed of high-density protective layers. At the same time, the two yarns are parallel and untwisted, which can share and disperse stress when impacted by sharp objects, effectively avoiding the risk of premature breakage of a single yarn due to stress concentration. The parallel yarns can form a wider and denser protective surface, reducing the gaps between the yarns and making the first-order structure more uniform and weak, thereby significantly improving the cut and puncture resistance of the outermost layer of the fabric.

[0037] Parameters: Knit 8 courses; let-off amount 1.8 mm / course; face density control 170-180 g / m². The face density of the four orders of the outer layer refers to the local grammage of the order, not the face density of the entire fabric.

[0038] Function: As the outermost defense line, it creates local resistance through high modulus and tight arrangement to resist knife puncture and convert point impact into surface impact, consuming initial energy.

[0039] 2) Second order (high-density tuck stitch):

[0040] Parameters: Use 800D high-strength and high-modulus polyethylene filaments; let-off amount 2.0 mm / course, as the let-off amount increases, the weft spacing increases, resulting in a decrease in the face density of this order; knit 6 courses; form 1 tuck every 3 stitches; face density control 140-150 g / m².

[0041] Function: It receives the stress transmitted from the first order, and the suspended arc structure formed by the tuck stitch has a certain elasticity, which can diffuse the concentrated stress from the first order to a wider area around the impact point, avoiding the rapid deepening of stress in the vertical direction and delaying the puncture process.

[0042] 3) Third order (medium-density tuck plain composite stitch):

[0043] Parameters: Use 800D high-strength and high-modulus polyethylene filaments; let-off amount 2.3 mm / course; alternate knitting tuck (1 tuck every 4 stitches) and plain structure, knit 5 courses; face density transitions to 120-130 g / m².

[0044] Function: The third stage is a transition zone with gradient changes. The reduction of surface density and the composite design of the structure make the stiffness gradually decrease and the flexibility increase, and continue to weaken and disperse the stress wave intensity from the second stage, realizing the smooth transition from "rigid resistance" to "flexible absorption", which is an important part of energy dissipation.

[0045] 4) Fourth stage (low-density tuck structure):

[0046] Parameters: Use 800D high-strength and high-modulus polyethylene filaments; let-off amount 2.6 mm / row; 1 tuck every 5 needles, weave 4 rows; surface density reduced to 100-110 g / m².

[0047] Function: As the last ring of the outer layer and the connecting preparation layer of the inner layer, its main role is to finally buffer the residual stress after the dissipation of the previous three stages, and to transmit the already greatly weakened stress to the inner layer in a more gentle manner. At the same time, its loose structure provides good compatibility for the integration of the loops of the outer top layer, ensuring the firmness of the interlayer combination.

[0048] The single density structure, when facing impact, will cause stress concentration due to impedance mutation, and is easily penetrated instantaneously. The continuous four-stage gradient design creates a smooth transition zone from extremely high impedance to medium impedance, avoiding stress wave reflection and superposition caused by drastic changes in material properties, so that impact energy can be attenuated more smoothly and efficiently.

[0049] (2) Inner layer (buffered skin-friendly inner layer)

[0050] The inner layer includes a top layer and a bottom layer, forming a three-dimensional spacing structure through double helical elastic connecting yarns, providing cushioning and breathability.

[0051] 1) Top layer:

[0052] Yarn: Yarn made of spandex and 800D high-strength and high-modulus polyethylene filaments (second yarn), with a mass ratio of spandex to polyethylene filaments of 10:90 and a twist of 600 twists per meter. This parameter design makes the second yarn maintain high strength while having excellent elasticity, providing ideal mechanical properties for the inner top layer.

[0053] Structure: Plain weave structure with high strength and elasticity.

[0054] 2) Bottom layer (skin-friendly layer):

[0055] Yarn: Spun cotton and modal blended yarn (third yarn), with a blend ratio of 7:3 and a yarn count of 32S.

[0056] Structure: Weave 1+1 rib structure to improve skin-friendliness and breathability.

[0057] 3) Connection system:

[0058] The double helix elastic connection yarn is composed of a 70D spandex yarn (elongation at break 550%) and a 75D polytrimethylene terephthalate (PTT) yarn (elongation at break 30%) by helical twisting.

[0059] Weaving method: connect the top layer and the bottom layer by alternating tuck knitting on the front and back needle beds to form a three-dimensional spacer layer, ensuring the cushioning performance and structural stability.

[0060] (3) Composite of outer layer and inner layer

[0061] The fourth order of the outer layer and the top layer of the inner layer are integrally formed by loop interlocking knitting. This structural interconnection realizes the "harmony of rigidity and flexibility" of collaborative protection, and the outer layer resists and disperses the cutting stress, and the inner layer absorbs and buffers the remaining energy:

[0062] The outer layer mainly undertakes the function of resistance, using its high modulus and high density to resist and disperse the piercing and cutting stress of sharp objects, and decompose the strong impact energy into multiple smaller energy packets. The inner layer mainly undertakes the function of "absorption", using the compressibility of its three-dimensional spacer structure and the stretchability of the elastic connection yarn to absorb and buffer the remaining energy transmitted from the outer layer. This "first hard resistance, then soft absorption" design forms a continuous, multi-mode energy dissipation channel. The outer layer solves the problem of traditional soft and cushioning structure being easily pierced by the initial piercing due to lack of surface rigidity; the inner layer solves the problem of traditional rigid protective materials causing blunt injury to the human body after the stress breaks through due to lack of buffering. The combination of the two improves the anti-piercing limit of the material to a new height.

[0063] In addition, the three-dimensional spacer structure of the inner layer not only provides cushioning, but also forms a continuous air channel, ensuring excellent air and moisture permeability. The skin-friendly bottom layer directly contacts the skin, providing a comfortable wearing experience. This makes the protective equipment not only provide safety protection, but also suitable for long-term wear, solving the problem of traditional anti-piercing clothing being heavy, hot and rigid.

[0064] 2. Preparation process

[0065] An integrated knitting is carried out by using a warp knitting machine equipped with double needle bed and multi-axial weft insertion device, and the specific steps are as follows:

[0066] S1. Yarn configuration and system preparation: 800D high strength and high modulus polyethylene filament (first yarn) for weaving outer layer structure is configured in the first group of guide bars; spandex and 800D high strength and high modulus polyethylene filament twisted together (second yarn) for weaving inner layer top layer is configured in a front needle bed guide bar of the second group of guide bars; cotton and modal blended yarn (third yarn) for weaving inner layer bottom layer is configured in a back needle bed guide bar of the second group of guide bars; the double helix elastic connecting yarn is configured in the interval guide bar.

[0067] S2. Integrated weaving of outer layer and inner layer structure: start the warp knitting machine, and synchronously execute the following actions under program control:

[0068] (a) Weaving outer layer four-step density gradient structure

[0069] The first yarn is laid by multi-axial weft insertion device, and at the same time, loop formation is fixed on the front needle bed by the first group of guide bars, to form a gradient structure from the first step to the fourth step in sequence; seamless connection is achieved between each step by continuous weaving of the guide bar.

[0070] (b) Weaving inner layer and compounding with outer layer

[0071] At the same time of starting to weave the fourth step of the outer layer, the front needle bed guide bar is started to feed the second yarn, and the top layer of the inner layer is continuously woven on the front needle bed, at which time the loop of the fourth step of the outer layer and the starting course loop of the top layer of the inner layer are integrally connected by loop interlocking.

[0072] At the same time, the back needle bed guide bar is started to feed the third yarn cotton / modal blended yarn, and the bottom layer of the inner layer (1+1 rib structure) is woven on the back needle bed.

[0073] The double helix elastic connecting yarn is fed by the interval guide bar, and is alternately tuck-knitted in a 'V' shape on the front and back needle beds, to connect the top layer and the bottom layer, and form a three-dimensional interval layer.

[0074] S3, Cycle:

[0075] Repeat step S2 until the fabric base fabric of the required length is woven.

[0076] S4. Post-finishing:

[0077] Heat setting: the base fabric is introduced into a heat setting machine under a tension of 5N / m, and is heat treated at 100°C, to relax the internal stress of the fiber.

[0078] Fast cooling: cooled to below 40°C at a cooling rate of 15°C / min, to inhibit the formation of large size crystals of UHMWPE, promote microcrystalline structure, and improve toughness and flexibility.

[0079] Finally, the fabric is rolled up to obtain a fabric with smooth surface and stable size.

[0080] 3. Performance test

[0081] After the warp knitting, the fabric thickness is 1.4 mm, and the area density is 720 g / m². According to the standard of GA 68-2024 "Police Stab-Proof Clothing", the standard knife D1 of Class A stab-proof clothing is used for testing, and the fabric is not penetrated under the impact energy of 24J. In addition, the fabric achieves a balance between protection, flexibility and comfort, the outer layer gradient structure effectively resists cutting, the inner layer spacing structure provides impact buffering and air permeability, and the bottom layer is skin-friendly and comfortable.

[0082] Through the integrated design of four-order density gradient and three-dimensional spacing layer, the balance of "protection-flexibility" is realized, the stab-proof standard is achieved without multi-layer superposition, the grammage is reduced by more than 40% compared with the traditional structure, and it is suitable for long-time wearing.

[0083] Example 2

[0084] This embodiment provides a flexible anti-cutting fabric with an area density of 480 g / m², which has the same overall structural principle as Example 1, including the integrated composite design of the outer layer four-order density gradient structure and the inner layer three-dimensional spacing layer, but through adjusting the material parameters and structural details, a lighter and thinner design is realized. The differences from Example 1 are described in detail below.

[0085] 1. Fabric structure design

[0086] (1) Outer layer

[0087] First order: using "double yarn parallel filling" process, two 400D aramid yarns (Kevlar 29, first yarn) are simultaneously inserted in parallel without twist (strength 25 cN / dtex), the delivery amount is 2.2 mm / row, the knitting is 7 rows, and the area density is 115-120 g / m².

[0088] Second order: select 400D aramid yarn (Kevlar 29), delivery amount 2.4 mm / row, form 1 loop every 4 needles, knit 6 rows, area density 105-110 g / m².

[0089] Third order: select 400D aramid yarn (Kevlar 29), delivery amount 2.6 mm / row, knit loop (1 loop every 5 needles) and plain structure, knit 5 rows, area density 95-100 g / m².

[0090] Fourth order: select 400D aramid yarn (Kevlar 29), delivery amount 2.8 mm / row, 1 loop every 6 needles, knit 3 rows, area density reduced to 80-90 g / m².

[0091] (2) Inner layer

[0092] The inner structure is the same as in Example 1, including a top layer, a bottom layer, and a connecting system, but the material parameters are different:

[0093] Top layer: The second yarn is a twisted yarn of spandex and 400D aramid, with a spandex to aramid mass ratio of 5:95 and a twist of 500 twists / meter. The weave is a plain weave.

[0094] Bottom layer: 32-count yarn (third yarn) blended with lyocell and cotton fibers in a 50 / 50 ratio, woven in a 1+1 rib structure.

[0095] Connection system: Same as in Example 1, using double helix elastic connecting yarn (composed of 70D spandex and 75D PTT), connecting the top layer and bottom layer by alternating loop knitting on the front and back needle beds.

[0096] The outer fourth layer and the inner top layer are integrally formed by coil stringing, as in Example 1.

[0097] 2. Preparation process

[0098] The preparation process is the same as in Example 1, using a warp knitting machine equipped with a double needle bed and a multi-axial weft insertion device, but the finishing parameters are different:

[0099] Heat setting: The fabric greige is fed into the heat setting machine under a tension of 5 N / m and heat-treated at 60°C. The lower tension and temperature treatment is used to lock in the fabric shape and protect the soft hand feel.

[0100] Cooling: Rapid cooling and shaping at a cooling rate of 10°C / min.

[0101] Other steps (such as the order of weaving the outer and inner layers) are the same as in Example 1.

[0102] 3. Performance Testing

[0103] After weaving, the fabric thickness is 1.2mm and the areal density is 480g / m². According to the GA 68-2024 "Police Stab-Proof Vest" standard, using a Class A stab-proof vest standard knife D1 test, two layers are required to achieve an impact energy of 24J without being penetrated.

[0104] Example 3

[0105] This embodiment provides a flexible cut-resistant fabric with an areal density of 970 g / m². Its overall structural principle is the same as in Embodiment 1, including an integrated composite design of an outer layer with a four-level density gradient structure and an inner three-dimensional spacer layer. However, by using higher-performance materials and tighter structural parameters, stronger protective performance is achieved. The differences from Embodiment 1 are described in detail below.

[0106] 1. Fabric structure design

[0107] (1) Outer layer

[0108] First stage: using "double-filament parallel weft insertion" process, two 1000D PBO filaments (strength 30 cN / dtex) are inserted simultaneously in parallel without twist, with a delivery amount of 1.8 mm / row, knitted for 10 rows, with a surface density of 240-250 g / m².

[0109] Second stage: using 1000D PBO filaments, with a delivery amount of 2.0 mm / row, forming a tuck every 3 stitches, knitted for 8 rows, with a surface density of 220-230 g / m².

[0110] Third stage: using 1000D PBO filaments, with a delivery amount of 2.2 mm / row, knitted with tuck (1 tuck every 4 stitches) and plain structure, knitted for 6 rows, with a surface density of 160-170 g / m². The decrease rate of the third stage to the second stage is about 26.1%, which is suitable for the high stiffness characteristics of PBO fibers, ensuring that stress is quickly dispersed and not concentrated.

[0111] Fourth stage: using 1000D PBO filaments, with a delivery amount of 2.4 mm / row, 1 tuck every 5 stitches, knitted for 5 rows, with a surface density of 140-150 g / m².

[0112] (2) Inner layer

[0113] The inner layer structure is the same as Example 1, including a top layer, a bottom layer, and a connecting system, but the material parameters are different:

[0114] Top layer: the second yarn is a twisted yarn composed of spandex and PBO filaments, with a mass ratio of spandex to PBO of 15:85, and a twist of 600 twists / meter. Plain weave is knitted.

[0115] Bottom layer: using pure cotton yarn with a yarn count of 60S, rib weave is knitted to improve skin-friendliness and air permeability.

[0116] Connecting system: same as Example 1, using double helical elastic connecting yarn (composed of 70D spandex and 75D PTT), connecting the top layer and the bottom layer by alternately knitting tucks on the front and back needle beds.

[0117] The fourth stage of the outer layer and the top layer of the inner layer are integrally compounded by loop interlocking, same as Example 1.

[0118] 2. Preparation process

[0119] The preparation process steps are the same as Example 1, using a warp knitting machine equipped with double needle beds and multi-axial weft insertion devices, but the finishing parameters are different:

[0120] Heat setting: The fabric is introduced into a heat setting machine under a tension of 8 N / m and heat treated at 90 °C to relax the internal stress of the fibers.

[0121] Cooling: The setting is rapidly cooled at a cooling rate of 15 °C / min.

[0122] Other steps (such as the order of knitting the outer and inner layers) are the same as in Example 1.

[0123] 3. Performance test

[0124] After warp knitting, the fabric has a thickness of 2.3 mm and a surface density of 970 g / m2. According to the standard of GA 68-2024 "Police Anti-stab Clothing", the standard knife D1 of Class A anti-stab clothing is used for testing, and a single layer can reach 24J impact energy without being penetrated, providing a choice for practitioners with higher requirements for protective performance.

[0125] Comparative Example 1

[0126] As a comparison, the present comparative example provides an anti-cut and stab fabric, which has the same inner layer structure as Example 1, and only the outer layer structure is adjusted: the outer layer uses a single tuck stitch with a grammage of about 540 g / m2, without density gradient design. The specific parameters are as follows:

[0127] Outer layer:

[0128] Yarn: The same 800D high-strength and high-modulus polyethylene filament (strength 32 cN / dtex) as in Example 1 is selected.

[0129] Structure: Single tuck stitch, 1 tuck every 4 stitches, the delivery amount is uniformly set to 2.2 mm / row, and 23 rows are continuously knitted without density gradient change.

[0130] Preparation process:

[0131] Except for the outer layer knitting parameters, the remaining steps (including the inner layer structure, composite method and post-finishing process) are the same as in Example 1.

[0132] Performance test:

[0133] After warp knitting, the fabric has a thickness of 1.3 mm and a total surface density of 715 g / m2. According to the standard of GA 68-2024 "Police Anti-stab Clothing", the standard knife D1 of Class A anti-stab clothing is used for testing, and the results show that a single layer of fabric cannot resist 24J impact energy and is penetrated by the knife tip during testing.

[0134] In the case of yarn material being completely consistent with example 1, the anti-cutting performance of comparative example 1 is significantly reduced due to the lack of gradient density design of the outer layer structure. When a sharp object such as a knife impacts, the energy is concentrated at the contact point of the knife tip, and a single organizational structure cannot effectively achieve stress step-by-step dispersion and multi-level energy dissipation, resulting in concentrated stress rapidly penetrating the fabric.

[0135] The results show that relying only on high-strength yarns or surface treatment, without the gradient density structure of "outer dense and inner sparse", it is difficult to meet the high-strength anti-cutting requirements. This further confirms the key role of the four-order density gradient design in the present application in achieving continuous energy attenuation and improving anti-cutting performance.

[0136] The above only describes the preferred embodiments of the present application, and does not limit the implementation and protection scope of the present application. For those skilled in the art, it should be realized that any equivalent replacement and obvious changes made by applying the content of the present application should be included in the protection scope of the present application.

Claims

1. A flexible cut-resistant fabric, comprising an outer layer and an inner layer, characterized in that, The outer layer is a four-level density gradient knitted structure, consisting of four levels from the outside to the inside: the first level, the second level, the third level, and the fourth level. The areal density of the four-level density gradient knitted structure decreases gradually from the outside to the inside, and adjacent levels are seamlessly connected through transition zones formed by knitting. The areal density of the first level is 110-250 g / m²; the areal density of the second level is 5%-30% lower than that of the first level; the areal density of the third level is 5%-30% lower than that of the second level; and the areal density of the fourth level is 5%-30% lower than that of the third level. Specifically, the first level is an ultra-dense weft-inserted structure, the second level is a high-density tucked structure, the third level is a medium-density tucked-plain weave composite structure, and the fourth level is a low-density tucked structure. The outer layer is woven from the first yarn. The first yarn has a count of 100-1000D and a yarn strength ≥20cn / dtex. The inner layer has a three-dimensional spacer structure, including a top layer, a bottom layer, and a connecting system. The top layer is woven from a second yarn, which is made by twisting spandex with the first yarn. The bottom layer is woven from a third yarn. The connecting system consists of two yarns with different elasticities twisted in a spiral manner and connected between the top and bottom layers by alternating loops on the front and back needle beds, forming a three-dimensional spacer layer to buffer impact. The third yarn is selected from one or more blends of cotton, modal, lyocell, and bamboo fiber. The fourth layer of the outer layer and the top layer of the inner layer are integrally formed by a knitting method in which loops are interlocked.

2. The flexible cut-resistant fabric according to claim 1, characterized in that, The first yarn is prepared by blending one or more of polyethylene, aramid, PBO filament, nylon, polyester, and metal wire.

3. The flexible cut-resistant fabric according to claim 1, characterized in that, The mass ratio of the spandex to the first yarn in the twist is 3:97 to 15:85, and the twist is 400 twists / meter to 800 twists / meter.

4. The flexible cut-resistant fabric according to claim 1, characterized in that, Both yarns with different elasticities are elastic yarns, including one high-elasticity yarn and one medium-elasticity yarn; the breaking elongation of the high-elasticity yarn is ≥50%, and the breaking elongation of the medium-elasticity yarn is 20%~40%.

5. The flexible cut-resistant fabric according to claim 1, characterized in that, The weight of the flexible cut-resistant fabric is 280g / m² to 1000g / m².

6. A method for preparing a flexible cut-resistant fabric as described in any one of claims 1-5, characterized in that, Integrated knitting is performed using a multi-axial warp knitting machine equipped with a double needle bed. The warp knitting machine is equipped with a multi-axial weft insertion device and multiple guide bars. The guide bars include a first set of guide bars for knitting the outer layer, a second set of guide bars for knitting the inner layer, and spacer guide bars for forming a connecting system. The process includes the following steps: S1. Yarn Configuration and System Preparation: Configure the yarn to the corresponding guide bars and set the knitting program; that is, configure the first yarn for knitting the outer layer structure to the first group of guide bars; configure the second yarn for knitting the inner top layer to a front needle bed guide bar in the second group of guide bars; configure the third yarn for knitting the inner bottom layer to a back needle bed guide bar in the second group of guide bars; configure the double helix elastic connecting yarn to the spacer guide bars; S2. Integrated knitted outer and inner layer structure: Upon starting the warp knitting machine, under program control, the multi-axial weft insertion device works in conjunction with each guide bar to synchronously execute the following knitting actions: (a) Weaving outer layer fourth-order density gradient structure The first yarn is laid using a multi-axial weft insertion device, and simultaneously fixed in loops by the first set of guide bars on the front needle bed, forming a knitted structure with a gradually decreasing surface density from the outside to the inside. A transition zone is set between each step, allowing the guide bars of the next step to intervene before the previous step is completed, so that the yarns of adjacent steps naturally interweave and interlock during the knitting process, forming an integrated connection structure. The four-step density gradient structure sequentially includes: a first-step ultra-dense weft insertion structure formed by simultaneously feeding two first yarns in parallel without twist in the same row; a second-step high-density tucked structure formed inside the first step by adjusting the weft yarn density and tucked structure; a third-step medium-density tucked-plain weave composite structure formed by further adjusting the yarn arrangement density and structure; and a fourth-step low-density tucked structure formed by increasing the weft yarn spacing. The decrease rate of surface density for each step is 5% to 30%. (b) Weaving the inner three-dimensional spaced structure and achieving interlayer composite: While weaving the outer fourth-order structure, the second yarn is fed in through the front needle bed comb and weaving continues on the front needle bed to form the top layer of the inner layer; simultaneously, the third yarn is fed in through the back needle bed comb and the bottom layer of the inner layer is woven on the back needle bed; double helical elastic connecting yarn is fed in through the spaced comb, and the double helical elastic connecting yarn is alternately looped and woven on the front and back needle beds in a 'V' or 'W' shape to connect the top layer and the bottom layer, forming the connecting system and the three-dimensional spaced structure; wherein, the fourth order of the outer layer and the top layer of the inner layer are integrally composited by a knitting method in which loops are interlocked; S3. Cycle: All combing systems of the machine operate synchronously and in coordination, repeating step S2 until the required length of fabric greige is woven; S4. Finishing: The fabric greige obtained in step S3 is introduced into a heat setting machine with a tension of 5~10N / m, and heat-treated at a temperature of 60~105℃. Then it is cooled and set to obtain a flexible cut-resistant fabric with a smooth surface and stable dimensions.

7. The preparation method according to claim 6, characterized in that, In step S1, when weaving the first-order ultra-dense weft-insertion structure, the "double-filament parallel weft-insertion" method is adopted, that is, the two first yarns are fed in parallel and without twist in the same weaving row through the weft-insertion device.

8. The preparation method according to claim 6, characterized in that, In step S4, immediately after heat setting, the product enters the cooling zone for rapid cooling and setting, cooling to below 40°C at a cooling rate of not less than 10-20°C / minute.