Police protection material and preparation method thereof

Abstract

The invention discloses a police protective material and a preparation method thereof. The material is divided into a double-layer structure including a puncture-resistant surface layer and a composite energy-absorbing bottom layer in the impact direction. The puncture-resistant surface layer is composed of poly (p-phenylene benzobisoxazole) fibers, aramid fibers and UHMWPE fibers, the PBO fibers are densely woven in a hexagonal honeycomb shape, and the aramid fibers and the UHMWPE fibers are wound through a double-helix structure. The composite energy-absorbing bottom layer is formed by filling polyurethane foam into an aluminum alloy honeycomb framework subjected to micro-arc oxidation treatment and is bonded with the puncture-resistant surface layer in a hot-pressing mode through a copolyamide hot melt adhesive film, and the total thickness is only 10-15 mm. The preparation method comprises the steps of fiber double-helix winding, honeycomb weaving, micro-arc oxidation, polyurethane injection molding and the like. Through the synergistic effect of honeycomb rigid puncture resistance, spiral friction energy absorption and foam plastic deformation, the thickness of the material is reduced by 40% compared with that of a traditional product under the same protection capacity, and the material has the advantages of light weight and high protection performance and is suitable for police equipment such as body armor and the like.

Description

Technical Field

[0001] This invention relates to the field of protective materials technology, specifically to protective materials for police use. These materials have puncture and bulletproof functions and can be used to make bulletproof vests. The invention also relates to a method for preparing such protective materials. Background Technology

[0002] Police protective materials are designed specifically for police officers and are functional materials used to reduce the impact of physical shocks, sharp instruments, explosive fragments, or gunshots. These materials are typically made of high-strength fibers, composite materials, or metal alloys and are processed into equipment such as bulletproof vests. Their core principle is to convert impact force into heat or kinetic energy dissipation through the energy absorption, dispersion, or reflection properties of the material, thereby reducing harm to the human body.

[0003] The core function of these materials is to protect the lives of police officers in high-risk environments. In violent crimes, terrorist attacks, or mass incidents, body armor can withstand handgun and even rifle fire; for example, in drug enforcement operations, stab-proof vests prevent knife penetration; and in counter-terrorism raids, composite armor can withstand the shockwaves of explosions. This equipment significantly improves the survivability of law enforcement personnel, allowing them to focus more intently on performing their duties when facing danger.

[0004] Despite continuous technological advancements, police protective materials still have significant limitations. Firstly, there is a trade-off between weight and flexibility; heavy body armor can impede tactical movements, and prolonged wear can lead to muscle fatigue.

[0005] Patent application CN115420146A discloses a novel lightweight bulletproof insert protective structure and its manufacturing method. Along the impact direction, it consists of a crack-resistant layer, a ceramic layer, a fiber layer, and a dent-reducing layer. The crack-resistant layer is made of lightweight aluminum alloy, the ceramic layer is a single piece or spliced ​​alumina or silicon carbide ceramic, and the fiber layer is composed of aramid non-woven fabric and PE non-woven fabric. Among protective structures with the same level of bulletproof protection, it is lighter and less expensive. However, as a bulletproof vest, there is still room for further improvement in terms of lightweight design.

[0006] The invention patent application with publication number CN119308068A provides a hexagonal honeycomb three-dimensional weaving device and its weaving method, which solves the problems of low error tolerance and monotonous force direction in the prior art, and achieves efficient weaving effect and multi-directional force bearing capacity of materials, and is suitable for a variety of industrial applications. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a police protective material that is lightweight yet has excellent puncture and bulletproof properties.

[0008] To achieve the above objectives, the present invention provides the following technical solution. A police protective material, comprising a puncture-resistant surface layer and a composite energy-absorbing bottom layer along the impact direction; the puncture-resistant surface layer is composed of poly(p-phenylene benzodioxazole) fiber (PBO fiber), aramid fiber, and ultra-high molecular weight polyethylene fiber (UHMWPE). The PBO fiber is densely woven in a hexagonal honeycomb pattern, and the aramid fiber and UHMWPE fiber are wound around the PBO fiber in a double-helix structure. The areal density of the puncture-resistant surface layer is 380±20 g / m³. 2 The composite energy-absorbing bottom layer is composed of polyurethane foam embedded in an aluminum alloy honeycomb skeleton. The aluminum alloy honeycomb skeleton undergoes micro-arc oxidation treatment, forming an alumina ceramic layer with a thickness of 15-20 μm, a pore size of 2-5 mm, and a foam density of 0.35-0.45 g / cm³. 3 The puncture-resistant surface layer and the composite energy-absorbing bottom layer are connected by a copolyamide hot melt adhesive film.

[0009] Among the aforementioned technical features, the puncture-resistant outer layer, as the outermost layer of the protective material, directly resists impact and puncture threats. It is composed of three high-performance fibers: poly(p-phenylene benzodioxazole) fiber, an ultra-high-strength synthetic fiber with high modulus and excellent tensile strength; aramid fiber, possessing high toughness and impact resistance; and ultra-high molecular weight polyethylene fiber, exhibiting good impact resistance and low density. The hexagonal honeycomb weave is a specific weaving structure where PBO fibers are densely arranged in hexagonal cells to form a honeycomb-like geometric pattern, used to evenly disperse impact force and enhance the material's stiffness and stability. The composite energy-absorbing bottom layer, as the bottom layer of the protective material, consists of an aluminum alloy honeycomb skeleton filled with polyurethane foam. The aluminum alloy skeleton undergoes micro-arc oxidation treatment, forming an alumina ceramic layer on the surface to improve the skeleton's wear resistance and compressive strength.

[0010] In the impact direction, the surface layer provides a rigid skeleton through the hexagonal honeycomb weave of PBO fibers, evenly distributing puncture or impact forces and preventing localized penetration. Simultaneously, the double-helix winding of aramid and UHMWPE fibers introduces a dynamic friction mechanism. When impact occurs, the helical structure deforms under pressure, and the frictional force generated between the fibers absorbs and converts kinetic energy into heat energy; the aluminum alloy honeycomb skeleton reflects or blocks the transmission of shock waves. When the shock wave reaches the bottom layer, the foam is compressed within a pore size of 2-5mm, converting kinetic energy into internal heat, further reducing harm to the human body.

[0011] As a preferred technical solution, based on the puncture-resistant surface layer, the weight ratio of poly(p-phenylene benzodioxazole) fiber, aramid fiber, and ultra-high molecular weight polyethylene fiber is (50-60):(20-30):(15-25). PBO fiber has a high elastic modulus and dominates the proportion, providing a rigid skeleton to resist penetration by sharp objects. The hexagonal, densely woven honeycomb arrangement requires a sufficient amount of PBO to form a continuous rigid network; a low proportion may cause the honeycomb structure to collapse, failing to effectively disperse impact force. In the double helix structure of aramid and UHMWPE, a higher aramid content enhances dynamic friction between fibers; the role of a small amount of UHMWPE is to fill the gaps between PBO and aramid, delaying crack propagation, while simultaneously reducing the overall material density and processing difficulty.

[0012] As a preferred technical solution, in the hexagonal honeycomb structure of the puncture-resistant surface layer, the side length of the hexagonal honeycomb structure is 0.2-0.5 mm, and the pitch of the double helix structure of the aramid fiber and ultra-high molecular weight polyethylene fiber is 20-50 μm. Here, when the side length is <0.2 mm, the honeycomb unit is too small, leading to an increased weaving defect rate; when the side length is >0.5 mm, the honeycomb structure's ability to deflect sharp objects is weakened. The pitch of 20–50 μm corresponds to the fiber tension, ensuring that the fibers are tightly wound without damaging the matrix.

[0013] As a preferred technical solution, the total thickness of the protective material is 10-15mm, of which the puncture-resistant surface layer accounts for 30-40% of the thickness and the composite energy-absorbing bottom layer accounts for 60-70% of the thickness. When the total thickness is <10mm, the compression stroke of the bottom polyurethane foam is somewhat limited; when the total thickness is >15mm, the wearing flexibility decreases. The surface thickness ratio here is a choice made to achieve a balance between rigidity and flexibility between the impact-resistant surface layer and the composite energy-absorbing bottom layer.

[0014] As a preferred technical solution, the thickness of the copolyamide hot melt adhesive film before hot melting is 0.2-0.5 mm. When the thickness is <0.2 mm, the molten colloid is difficult to completely fill the interfacial gap between the two layers, and the adhesive layer is too thin during hot pressing and is easily extruded, resulting in local areas without adhesive bonding; when the thickness is >0.5 mm, the adhesive film forms an excessively thick flexible interlayer after curing, which weakens the efficiency of impact energy transfer from the surface to the bottom layer. The copolyamide is connected to the polar groups on the fiber surface through amide bonds (-NH-CO-) through hot pressing, providing good support and stable curing between the two, facilitating kinetic energy transfer.

[0015] The present invention also provides a method for preparing a police protective material having any one or more of the above-described technical features, comprising the following steps: S1, Aramid fibers and ultra-high molecular weight polyethylene fibers are wound in a double helix structure onto poly(p-phenylenebenzodioxazole) fibers; S2, then the poly(p-phenylene) wrapped with aramid fiber and ultra-high molecular weight polyethylene fiber is densely woven in a hexagonal honeycomb pattern, while controlling the areal density of the puncture-resistant surface layer to obtain the puncture-resistant surface layer. S3. Take an aluminum alloy honeycomb skeleton, perform micro-arc oxidation treatment on its surface to generate an alumina ceramic layer, and inject polyurethane foam into the aluminum alloy honeycomb skeleton to obtain a composite energy-absorbing bottom layer. S4, a copolyamide hot melt adhesive film is laid between the puncture-resistant surface layer and the composite energy-absorbing bottom layer, and the whole is hot-pressed.

[0016] As a preferred technical solution, in step S1, a dual-station winding machine is used to double-spiral wind aramid fibers with a twist of 400 twists / meter and ultra-high molecular weight polyethylene (UHMWPE) with a twist of 600 twists / meter, with the winding tension controlled at 5-8 N. The aramid twist of 400 twists / meter improves fiber bundle cohesion and prevents breakage due to friction during winding; the UHMWPE twist of 600 twists / meter maintains its high tensile strength while adapting to the winding tension. Too low a winding tension will result in a loose spiral structure, weakening the energy absorption effect of dynamic friction; too high a tension will damage the PBO fiber body, leading to a higher breakage rate.

[0017] As a preferred technical solution, in step S2, a rapier loom is used for dense weaving at a warp and weft density of 120-150 warp threads / inch, while simultaneously controlling the side length of the honeycomb units. The weft insertion force of the rapier loom is higher than that of the air-jet loom, which helps to overcome the rigid resistance of high-modulus PBO fibers and reduce or even avoid warp breakage.

[0018] As a preferred technical solution, in step S3, the electrolyte for micro-arc oxidation contains: sodium silicate 10g / L, sodium phosphate 6g / L, sodium tungstate 2g / L, pulse power supply frequency 800Hz, voltage 450V, and micro-arc oxidation processing time 18-22min; polyurethane foam is injected into the aluminum alloy honeycomb skeleton using an injection molding machine at a pressure of 0.8-1.2MPa.

[0019] As a preferred technical solution, in step S4, the puncture-resistant surface layer and the composite energy-absorbing bottom layer are heated to 120-140°C and pressurized to 0.5-1.5MPa. After hot pressing, the layers are cooled and shaped, and then ultrasonically sealed along the edge of the puncture-resistant surface layer.

[0020] The advantages and beneficial effects of this invention are as follows: PBO fibers are densely packed in a hexagonal honeycomb structure to provide rigidity and disperse impact force; aramid and UHMWPE are double-helically wound between the fibers to generate dynamic friction; the deformation of the helical structure absorbs the puncture kinetic energy and inhibits the crack propagation path; the three-component fiber combines the high modulus of PBO, the toughness of aramid, and the self-lubricating properties of UHMWPE.

[0021] The micro-arc anodized aluminum alloy honeycomb skeleton enhances hardness and resists shock wave transmission. Combined with low-density polyurethane foam filling the honeycomb cells, it converts residual kinetic energy into heat energy through compression plastic deformation. The police protective material of this invention, while offering the same ballistic protection capability, has a total thickness of only 10-15mm, approximately 40% thinner than similar products, significantly improving duty flexibility and durability. Detailed Implementation

[0022] The specific embodiments of the present invention will be further described below. The following examples are only used to more clearly illustrate the technical solutions of the present invention, and should not be used to limit the scope of protection of the present invention.

[0023] Example 1: A method for preparing a police protective material, comprising the following steps: S1: Using a dual-station winding machine, aramid fiber (400 twists / meter) and ultra-high molecular weight polyethylene fiber (600 twists / meter) are wound into a double helix structure with a pitch of 30μm on poly(p-phenylene benzodioxazole) fiber. The weight ratio of poly(p-phenylene benzodioxazole) fiber, aramid fiber and ultra-high molecular weight polyethylene fiber is 55:25:20, and the winding tension is controlled at 6N.

[0024] S2: Poly(p-phenylene) fibers wound with aramid and ultra-high molecular weight polyethylene fibers are densely woven into a hexagonal honeycomb pattern using a rapier loom at a warp and weft density of 130 threads / inch. The honeycomb side length is 0.35 mm, while the total areal density of the puncture-resistant surface layer is controlled at 380 g / m².

[0025] S3: An aluminum alloy honeycomb skeleton with a pore size of 3mm was subjected to micro-arc oxidation treatment on its surface. The electrolyte for micro-arc oxidation contained 10g / L sodium silicate, 6g / L sodium phosphate, and 2g / L sodium tungstate. The aluminum alloy honeycomb skeleton was placed in the electrolyte and connected to a pulse power supply at a frequency of 800Hz and a voltage of 450V for 19min. After treatment, an alumina ceramic layer with a thickness of 18μm was formed on the surface. Next, polyurethane foam with a foam density of 0.38 g / cm³ was injected into the skeleton using an injection molding machine at a pressure of 0.9MPa to obtain a composite energy-absorbing bottom layer.

[0026] S4: Lay a 0.3mm thick copolyamide hot melt adhesive film between a 4.2mm thick puncture-resistant top layer and a 7.8mm thick composite energy-absorbing bottom layer. Heat the entire layer to 130℃, then apply 1.0MPa for hot pressing. After completion, cool and set the shape, and then ultrasonically seal the edges along the puncture-resistant top layer.

[0027] Example 2: A method for preparing a police protective material, comprising the following steps: S1: Using a dual-station winding machine, aramid fiber (400 twists / meter) and ultra-high molecular weight polyethylene fiber (600 twists / meter) are wound into a double helix structure with a pitch of 35μm on poly(p-phenylene benzodioxazole) fiber. The weight ratio of poly(p-phenylene benzodioxazole) fiber, aramid fiber and ultra-high molecular weight polyethylene fiber is 58:22:20, and the winding tension is controlled at 7N.

[0028] S2: Poly(p-phenylene) fibers wound with aramid and ultra-high molecular weight polyethylene fibers are densely woven into a hexagonal honeycomb pattern using a rapier loom at a warp and weft density of 140 threads / inch. The honeycomb side length is 0.4 mm, while the total areal density of the puncture-resistant surface layer is controlled at 370 g / m².

[0029] S3: An aluminum alloy honeycomb skeleton with a pore size of 4mm was subjected to micro-arc oxidation treatment on its surface. The electrolyte for micro-arc oxidation contained 10g / L sodium silicate, 6g / L sodium phosphate, and 2g / L sodium tungstate. The aluminum alloy honeycomb skeleton was placed in the electrolyte and connected to a pulse power supply at a frequency of 800Hz and a voltage of 450V for 20min. After treatment, an alumina ceramic layer with a thickness of 16μm was formed on the surface. Next, polyurethane foam with a foam density of 0.40 g / cm³ was injected into the skeleton using an injection molding machine at a pressure of 1.1MPa to obtain a composite energy-absorbing bottom layer.

[0030] S4: Lay a 0.4mm thick copolyamide hot melt adhesive film between a 3.8mm thick puncture-resistant top layer and an 8.2mm thick composite energy-absorbing bottom layer. Heat the entire layer to 125℃, then apply 0.8MPa for hot pressing. After completion, cool and set, and then ultrasonically seal the edges along the puncture-resistant top layer.

[0031] Example 3: A method for preparing a police protective material, comprising the following steps: S1: Using a dual-station winding machine, aramid fiber (400 twists / meter) and ultra-high molecular weight polyethylene fiber (600 twists / meter) are wound into a double helix structure on poly(p-phenylene benzodioxazole) fiber with a pitch of 40μm. The weight ratio of poly(p-phenylene benzodioxazole) fiber, aramid fiber and ultra-high molecular weight polyethylene fiber is 54:26:20, and the winding tension is controlled at 5.5N.

[0032] S2: Poly(p-phenylene) fibers wound with aramid and ultra-high molecular weight polyethylene fibers are densely woven into a hexagonal honeycomb pattern using a rapier loom at a warp and weft density of 125 threads / inch. The honeycomb side length is 0.3 mm, while the total areal density of the puncture-resistant surface layer is controlled at 390 g / m².

[0033] S3: An aluminum alloy honeycomb skeleton with a pore size of 2.5 mm was subjected to micro-arc oxidation treatment on its surface. The electrolyte for micro-arc oxidation contained 10 g / L sodium silicate, 6 g / L sodium phosphate, and 2 g / L sodium tungstate. The aluminum alloy honeycomb skeleton was placed in the electrolyte and connected to a pulse power supply at a frequency of 800 Hz and a voltage of 450 V for 21 min. After treatment, an alumina ceramic layer with a thickness of 19 μm was formed on the surface. Next, polyurethane foam with a foam density of 0.42 g / cm³ was injected into the skeleton using an injection molding machine at a pressure of 1.0 MPa to obtain a composite energy-absorbing bottom layer.

[0034] S4: Lay a 0.35mm thick copolyamide hot melt adhesive film between a 4.5mm thick puncture-resistant top layer and a 7.5mm thick composite energy-absorbing bottom layer. Heat the entire layer to 135℃, then apply 1.2MPa for hot pressing. After completion, cool and set the shape, and then ultrasonically seal the edges along the puncture-resistant top layer.

[0035] Example 4: A method for preparing a police protective material, comprising the following steps: S1: Using a dual-station winding machine, aramid fiber (400 twists / meter) and ultra-high molecular weight polyethylene fiber (600 twists / meter) are wound into a double helix structure with a pitch of 25μm on poly(p-phenylene benzodioxazole) fiber. The weight ratio of poly(p-phenylene benzodioxazole) fiber, aramid fiber and ultra-high molecular weight polyethylene fiber is 57:23:20, and the winding tension is controlled at 6.5N.

[0036] S2: Poly(p-phenylene) fibers wound with aramid and ultra-high molecular weight polyethylene fibers are densely woven into a hexagonal honeycomb pattern using a rapier loom at a warp and weft density of 145 threads / inch. The honeycomb side length is 0.45 mm, while the total areal density of the puncture-resistant surface layer is controlled at 375 g / m².

[0037] S3: An aluminum alloy honeycomb skeleton with a pore size of 3.5 mm was subjected to micro-arc oxidation treatment on its surface. The electrolyte for micro-arc oxidation contained 10 g / L sodium silicate, 6 g / L sodium phosphate, and 2 g / L sodium tungstate. The aluminum alloy honeycomb skeleton was placed in the electrolyte and connected to a pulse power supply at a frequency of 800 Hz and a voltage of 450 V for 18.5 min. After treatment, an alumina ceramic layer with a thickness of 17 μm was formed on the surface. Next, polyurethane foam with a foam density of 0.36 g / cm³ was injected into the skeleton using an injection molding machine at a pressure of 0.85 MPa to obtain a composite energy-absorbing bottom layer.

[0038] S4: A 0.25mm thick copolyamide hot melt adhesive film is laid between a 3.6mm thick puncture-resistant top layer and a 7.4mm thick composite energy-absorbing bottom layer. The entire layer is heated to 138℃ and then hot-pressed under pressure of 0.7MPa. After completion, it is cooled and shaped, and ultrasonically sealed along the edges of the puncture-resistant top layer.

[0039] Example 5: A method for preparing a police protective material, comprising the following steps: S1: Using a dual-station winding machine, aramid fiber (400 twists / meter) and ultra-high molecular weight polyethylene fiber (600 twists / meter) are wound into a double helix structure with a pitch of 45μm on poly(p-phenylene benzodioxazole) fiber. The weight ratio of poly(p-phenylene benzodioxazole) fiber, aramid fiber and ultra-high molecular weight polyethylene fiber is 56:24:20, and the winding tension is controlled at 7.5N.

[0040] S2: Poly(p-phenylene) fibers wound with aramid and ultra-high molecular weight polyethylene fibers are densely woven into a hexagonal honeycomb pattern using a rapier loom at a warp and weft density of 135 threads / inch. The honeycomb side length is 0.25 mm, while the total areal density of the puncture-resistant surface layer is controlled at 385 g / m².

[0041] S3: An aluminum alloy honeycomb skeleton with a pore size of 4.5 mm was subjected to micro-arc oxidation treatment on its surface. The electrolyte for micro-arc oxidation contained 10 g / L sodium silicate, 6 g / L sodium phosphate, and 2 g / L sodium tungstate. The aluminum alloy honeycomb skeleton was placed in the electrolyte and connected to a pulse power supply at a frequency of 800 Hz and a voltage of 450 V for 22 min. After treatment, an alumina ceramic layer with a thickness of 20 μm was formed on the surface. Next, polyurethane foam with a foam density of 0.44 g / cm³ was injected into the skeleton using an injection molding machine at a pressure of 1.15 MPa to obtain a composite energy-absorbing bottom layer.

[0042] S4: Lay a 0.45mm thick copolyamide hot melt adhesive film between a 5.0mm thick puncture-resistant top layer and a 9.0mm thick composite energy-absorbing bottom layer. Heat the entire layer to 122℃, then apply 0.6MPa for hot pressing. After completion, cool and set the shape, and then ultrasonically seal the edges along the puncture-resistant top layer.

[0043] Example 6: A method for preparing a police protective material, comprising the following steps: S1: Using a dual-station winding machine, aramid fiber (400 twists / meter) and ultra-high molecular weight polyethylene fiber (600 twists / meter) are wound into a double helix structure with a pitch of 30μm on poly(p-phenylene benzodioxazole) fiber. The weight ratio of poly(p-phenylene benzodioxazole) fiber, aramid fiber and ultra-high molecular weight polyethylene fiber is 53:27:20, and the winding tension is controlled at 5.8N.

[0044] S2: Poly(p-phenylene) fibers wound with aramid and ultra-high molecular weight polyethylene fibers are densely woven into a hexagonal honeycomb pattern using a rapier loom at a warp and weft density of 120 threads / inch. The honeycomb side length is 0.42 mm, while the total areal density of the puncture-resistant surface layer is controlled at 360 g / m².

[0045] S3: An aluminum alloy honeycomb skeleton with a pore size of 2mm was subjected to micro-arc oxidation treatment on its surface. The electrolyte for micro-arc oxidation contained 10g / L sodium silicate, 6g / L sodium phosphate, and 2g / L sodium tungstate. The aluminum alloy honeycomb skeleton was placed in the electrolyte and connected to a pulse power supply at a frequency of 800Hz and a voltage of 450V for 18.2min. After treatment, an alumina ceramic layer with a thickness of 15μm was formed on the surface. Next, polyurethane foam with a foam density of 0.39 g / cm³ was injected into the skeleton using an injection molding machine at a pressure of 0.95MPa to obtain a composite energy-absorbing bottom layer.

[0046] S4: A 0.28mm thick copolyamide hot melt adhesive film is laid between a 5.2mm thick puncture-resistant top layer and a 7.8mm thick composite energy-absorbing bottom layer. The entire layer is heated to 140℃ and then hot-pressed under pressure of 1.4MPa. After completion, it is cooled and shaped, and ultrasonically sealed along the edges of the puncture-resistant top layer.

[0047] Example 7: A method for preparing a police protective material, comprising the following steps: S1: Using a dual-station winding machine, aramid fiber (400 twists / meter) and ultra-high molecular weight polyethylene fiber (600 twists / meter) are wound into a double helix structure with a pitch of 50μm on poly(p-phenylene benzodioxazole) fiber. The weight ratio of poly(p-phenylene benzodioxazole) fiber, aramid fiber and ultra-high molecular weight polyethylene fiber is 60:20:20, and the winding tension is controlled at 6.2N.

[0048] S2: Poly(p-phenylene) fibers wound with aramid and ultra-high molecular weight polyethylene fibers are densely woven into a hexagonal honeycomb pattern using a rapier loom at a warp and weft density of 150 threads / inch. The honeycomb side length is 0.48 mm, while the total areal density of the puncture-resistant surface layer is controlled at 400 g / m².

[0049] S3: An aluminum alloy honeycomb skeleton with a pore size of 5mm was subjected to micro-arc oxidation treatment on its surface. The electrolyte for micro-arc oxidation contained 10g / L sodium silicate, 6g / L sodium phosphate, and 2g / L sodium tungstate. The aluminum alloy honeycomb skeleton was placed in the electrolyte and connected to a pulse power supply at a frequency of 800Hz and a voltage of 450V for 21 minutes. After treatment, an alumina ceramic layer with a thickness of 19μm was formed on the surface. Next, polyurethane foam with a foam density of 0.45 g / cm³ was injected into the skeleton using an injection molding machine at a pressure of 1.2MPa to obtain a composite energy-absorbing bottom layer.

[0050] S4: Lay a 0.5mm thick copolyamide hot melt adhesive film between a 3.0mm thick puncture-resistant top layer and a 7.0mm thick composite energy-absorbing bottom layer. Heat the entire layer to 128℃, then apply 0.5MPa for hot pressing. After completion, cool and set, and then ultrasonically seal the edges along the puncture-resistant top layer.

[0051] Example 8: A preparation method of a police protection material, comprising the following steps: S1: Using a two-station winding machine, aramid fibers (twist 400 turns / m) and ultra-high molecular weight polyethylene fibers (twist 600 turns / m) are both wound around poly(p-phenylene benzobisoxazole) fibers in a double helix structure with a pitch of 22 μm. The weight ratio of poly(p-phenylene benzobisoxazole) fibers, aramid fibers and ultra-high molecular weight polyethylene fibers is 52:28:20, and the winding tension is controlled at 8 N.

[0052] S2: The poly(p-phenylene) fibers wound with aramid and ultra-high molecular weight polyethylene fibers are densely woven in a hexagonal honeycomb shape by a rapier loom with a warp and weft density of 128 threads / inch. The side length of the honeycomb is 0.22 mm, and at the same time, the total surface density of the anti-puncture surface layer is controlled at 365 g / m².

[0053] S3: Take an aluminum alloy honeycomb skeleton with a pore diameter of 3.2 mm, and perform micro-arc oxidation treatment on its surface. The electrolyte for micro-arc oxidation contains 10 g / L of sodium silicate, 6 g / L of sodium phosphate, and 2 g / L of sodium tungstate. Place the aluminum alloy honeycomb skeleton in the electrolyte, connect the pulse power supply, and treat it at a frequency of 800 Hz and a voltage of 450 V for 19.5 min. After treatment, an alumina ceramic layer with a thickness of 17.5 μm is formed on the surface. Then, use an injection molding machine to inject polyurethane foam with a foam density of 0.37 g / cm³ into the skeleton at a pressure of 1.05 MPa to obtain a composite energy-absorbing bottom layer.

[0054] S4: Lay a copolyamide hot-melt adhesive film with a thickness of 0.32 mm between the 4.9-mm thick anti-puncture surface layer and the 9.6-mm thick composite energy-absorbing bottom layer. Heat the whole to 132 °C, and then apply a pressure of 1.3 MPa for hot pressing. After completion, cool and shape it, and perform ultrasonic edge sealing along the edge of the anti-puncture surface layer.

[0055] Performance analysis and testing are carried out on the above examples. The bulletproof test is carried out according to NIJ 0101.06 Level IIIA, and a 44 Magnum semi-jacketed bullet (initial velocity 436 m / s) is selected for the test. It is qualified if the back depression is less than or equal to 44 mm. All examples are qualified after 4 bullet tests. The anti-puncture test is carried out according to NIJ 0115.00 STAB Level 1, and a standard cone knife with a tip radius of 0.5 mm is selected for puncture with an impact energy of 24 J. The puncture depth of each example is less than 7 mm, and the cutting depth < 20 mm, all of which are qualified. The surface density test is carried out according to ASTM D3776 "Standard for Mass per Unit Area of Textiles". Cut a 10×10 cm sample with an accuracy of ±0.1 cm², weigh it on a precision balance and then calculate. Calculate the surface density of the anti-puncture layer and the total surface density respectively. The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A police protective material, characterized in that: Along the direction of impact, it includes a puncture-resistant outer layer and a composite energy-absorbing bottom layer; The puncture-resistant surface layer is composed of poly(p-phenylene benzodioxazole) fibers, aramid fibers, and ultra-high molecular weight polyethylene fibers. The poly(p-phenylene benzodioxazole) fibers are densely woven in a hexagonal honeycomb pattern, and the aramid fibers and ultra-high molecular weight polyethylene fibers are wound around the poly(p-phenylene benzodioxazole) fibers in a double helix structure. The areal density of the puncture-resistant surface layer is 380±20 g / m³. 2 ; The composite energy-absorbing bottom layer is composed of polyurethane foam embedded in an aluminum alloy honeycomb skeleton. The aluminum alloy honeycomb skeleton undergoes micro-arc oxidation treatment, forming an alumina ceramic layer with a thickness of 15-20 μm, a pore size of 2-5 mm, and a foam density of 0.35-0.45 g / cm³. 3 ; The puncture-resistant surface layer and the composite energy-absorbing bottom layer are connected by a copolyamide hot melt adhesive film.

2. The police protective material according to claim 1, characterized in that: Based on the aforementioned puncture-resistant surface layer, the ratio of poly(p-phenylene benzodioxazole) fiber, aramid fiber, and ultra-high molecular weight polyethylene fiber by weight is (50-60):(20-30):(15-25).

3. The police protective material according to claim 2, characterized in that: In the hexagonal honeycomb structure of the puncture-resistant surface layer, the side length of the hexagonal honeycomb structure is 0.2-0.5 mm, and the pitch of the double helix structure of aramid fiber and ultra-high molecular weight polyethylene fiber is 20-50 μm.

4. The police protective material according to claim 2, characterized in that: The total thickness of the protective material is 10-15mm, of which the puncture-resistant surface layer accounts for 30-40% of the thickness and the composite energy-absorbing bottom layer accounts for 60-70% of the thickness.

5. The police protective material according to claim 2, characterized in that: The thickness of the copolyamide hot melt adhesive film before hot melting is 0.2-0.5 mm.

6. A method for preparing police protective material as described in any one of claims 1-5, characterized in that, Includes the following steps: S1, Aramid fibers and ultra-high molecular weight polyethylene fibers are wound in a double helix structure onto poly(p-phenylenebenzodioxazole) fibers; S2, then the poly(p-phenylene) wrapped with aramid fiber and ultra-high molecular weight polyethylene fiber is densely woven in a hexagonal honeycomb pattern, while controlling the areal density of the puncture-resistant surface layer to obtain the puncture-resistant surface layer. S3. Take an aluminum alloy honeycomb skeleton, perform micro-arc oxidation treatment on its surface to generate an alumina ceramic layer, and inject polyurethane foam into the aluminum alloy honeycomb skeleton to obtain a composite energy-absorbing bottom layer. S4, a copolyamide hot melt adhesive film is laid between the puncture-resistant surface layer and the composite energy-absorbing bottom layer, and the whole is hot-pressed.

7. The preparation method according to claim 6, characterized in that, In step S1, a dual-station winding machine is used to wind aramid fibers with a twist of 400 twists / meter and ultra-high molecular weight polyethylene with a twist of 600 twists / meter in a double helix, with the winding tension of the two fibers controlled at 5-8N.

8. The preparation method according to claim 6, characterized in that, In S2, a rapier loom is used to weave densely at a warp and weft density of 120-150 warp threads / inch, while controlling the side length of the honeycomb unit.

9. The preparation method according to claim 6, characterized in that, In step S3, the electrolyte for micro-arc oxidation contains: sodium silicate 10g / L, sodium phosphate 6g / L, sodium tungstate 2g / L, pulse power supply frequency 800Hz, voltage 450V, and micro-arc oxidation treatment time 18-22min; polyurethane foam is injected into the aluminum alloy honeycomb skeleton using an injection molding machine at a pressure of 0.8-1.2MPa.

10. The preparation method according to claim 6, characterized in that, In step S4, the puncture-resistant surface layer and the composite energy-absorbing bottom layer are heated to 120-140°C and pressurized to 0.5-1.5 MPa. After hot pressing, the layers are cooled and shaped, and then ultrasonically sealed along the edge of the puncture-resistant surface layer.

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