A shock-resistant, buffering, and energy-absorbing composite structure

Abstract

A composite structure for impact resistance, cushioning, and energy absorption comprises an impact protection layer, an energy dissipation layer, and a cushioning and energy absorption layer. The impact protection layer utilizes Kevlar fiber doped with methyldiphenylsilane-modified polyurea to resist fragment penetration. The energy dissipation layer utilizes modified ultra-high molecular weight polyethylene fiber, which enhances its toughness and further disperses impact energy. The modified ultra-high molecular weight polyethylene fiber is blended with methyldiphenylsilane-modified polyurea. The cushioning and energy absorption layer utilizes a cushioning and energy absorption elastomer doped with polymethyl acrylate microelements and aluminum tripolyphosphate particles. This cushioning and energy absorption elastomer exhibits excellent cushioning and energy absorption properties at both room and low temperatures and maintains these properties even in high-temperature environments.

Description

Technical Field

[0001] The invention relates to the technical field of impact-resistant protective structures, in particular to an impact-resistant, buffering, and energy-absorbing composite protective structure. Background Art

[0002] In many engineering and technical fields, such as military, firefighting, and construction, workers may face potential hazards from collisions, vibrations, and shocks. An efficient and reliable impact protection solution is needed to meet the protection needs of workers in various working environments. Current research on impact protection focuses primarily on improving material properties and designing single-material structures. However, relatively few literature and patents address the absorption and dispersion of impact energy at different levels, achieving multi-layered buffering and energy absorption.

[0003] Patent 202310120431.0 discloses a quick-assembled and editable impact-resistant energy-absorbing device that can meet the impact resistance requirements of emergency situations. Its shortcomings are that material selection and durability are difficult to guarantee. Although the invention provides flexibility and editability, how to accurately adjust the parameters of the device, the number of layers, and the arrangement of the spherical structure according to actual needs to obtain the best mechanical properties and energy absorption characteristics still requires certain technical knowledge and experimental verification.

[0004] Patent 201310602701.8 discloses an impact-resistant energy-absorbing material and its preparation method. This material forms a layered protection system, reducing damage to the entire composite panel caused by shock waves, thereby improving the material's impact resistance and energy absorption performance. However, while the rubber connector possesses high elasticity and plasticity, its compatibility with the metal panel and foam material, as well as its durability under long-term use, requires detailed research and testing. Rubber can be affected by environmental conditions, temperature fluctuations, and chemical substances, potentially affecting the strength and stability of the connection.

[0005] Patent CN201811571780.X discloses a composite bulletproof vest that relies on a bullet-absorbing layer, a protective layer, a buffer layer, and an energy-absorbing layer to protect the wearer from bullet damage. The bullet-absorbing structure in which an aluminum foam layer is sandwiched between two carbon fiber layers is used to prevent the generation of stray bullets; the buffer layer is used to convert point impacts into surface impacts; and the absorption layer is used to absorb deformation of the buffer layer. Its disadvantage is that the carbon fiber material is easy to break, and the choice of this material as the bullet-proof layer weakens the bullet-proof effect to a certain extent. In addition, the invention does not directly specify the thickness of the alumina ceramic plate of the protective layer, and the rigid protective material increases the weight of the bullet-proof structure, making it difficult to ensure lightness and comfort. Summary of the Invention

[0006] The purpose of the present invention is to provide an impact-resistant, buffering and energy-saving composite structure with strong impact resistance, excellent buffering and energy absorption effect, high fatigue strength and good environmental adaptability, which is used for the protection of personnel under impact, realizes multi-level dispersed absorption of impact energy, maintains the function of buffering and energy absorption characteristics in a wider temperature range, and at the same time ensures factors such as buffering and energy absorption performance, structural weight and volume, and has the characteristics of lightweight.

[0007] A composite structure for impact resistance and energy absorption, comprising an impact protection layer, an energy dissipation layer, and a buffering layer. The impact protection layer utilizes Kevlar fiber doped with methyldiphenylsilane-modified polyurea to resist fragment penetration. The energy dissipation layer utilizes modified ultra-high molecular weight polyethylene fiber, which enhances its toughness and further disperses impact energy. The modified ultra-high molecular weight polyethylene fiber is blended with methyldiphenylsilane-modified polyurea. The buffering layer utilizes a buffering elastomer doped with polymethyl acrylate microelements and aluminum tripolyphosphate particles. This buffering elastomer exhibits excellent energy absorption properties at room and low temperatures and maintains these properties even in high-temperature environments.

[0008] Specifically, the impact-resistant, buffering, and energy-absorbing composite structure is composed of three impact protection layers, one energy dispersion layer, and one buffering and energy-absorbing layer.

[0009] The three-layer structure effectively disperses impact energy, preventing fragment penetration while also dispersing energy and providing a buffering and energy-absorbing effect. The impact protection layer effectively resists fragment penetration and protects against direct damage. The energy dispersion layer, with its high toughness, further prevents fragment penetration and disperses energy through deformation, preventing it from being concentrated in a single point. The buffering and energy-absorbing layer not only absorbs most of the residual impact energy but also effectively reduces the structural convexity, making it suitable for protecting the human body from blunt impact injuries.

[0010] Specifically, the steps for manufacturing the methyldiphenylsilane-modified polyurea-doped Kevlar fiber used in the impact protection layer are as follows:

[0011] S1: 40% by mass of methyldiphenylsilane (90% purity) and 60% by mass of ethylenediamine, an amine compound for synthesizing polyurea, are mixed at 40-50°C, stirred for 10-20 minutes, and allowed to stand for 2-3 hours to obtain an amine compound containing a methyldiphenylsilane skeleton. This is then used to react with an isocyanate semi-prepolymer to obtain a methyldiphenylsilane-modified polyurea (A).

[0012] S2: To achieve better impregnation, 90% aliphatic amine curing agent and 10% methyldiphenylsilane-modified polyurea (A) were mixed and stirred at 300 rpm for 30 minutes, followed by ultrasonic treatment for 10 minutes and finally dried under vacuum for 90 minutes.

[0013] S3: Kevlar fiber was soaked in diluted methyl diphenylsilane modified polyurea (B) for 30 minutes and then dried for 72 hours to obtain modified Kevlar fiber.

[0014] Specifically, the modified ultra-high molecular weight polyethylene fiber used in the energy dissipation layer is prepared as follows:

[0015] A1: Combine 10% methyldiphenylsilane and 90% epoxy resin, stir at 500 rpm for 30 minutes, and then ultrasonicate for 10 minutes. Then, add an aliphatic amine curing agent to the mixture at a 10:1 mass ratio, stir at 500 rpm for 30 minutes, and then ultrasonicate for 10 minutes to obtain a resin-based solution.

[0016] A2: Mix the resin-based solution obtained in step 1 with the ultra-high molecular weight polyethylene obtained after hot melting in a mass ratio of 1:25, stir thoroughly and then cool to obtain modified ultra-high molecular weight polyethylene.

[0017] Specifically, the steps for preparing the doped polymethyl acrylate microelements and aluminum tripolyphosphate particles in the buffer energy-absorbing layer are as follows:

[0018] B1: In a reaction vessel, a certain proportion of methyl acrylate monomer, crosslinking agent, cationic surfactant and dispersant are stirred at 500 rpm for 10-20 minutes, and then an initiator is added. The stirred solution is placed in an environment of 45-65°C to react for 3-4 hours to obtain polymethyl acrylate microelements.

[0019] B2: Ethylene glycol methyl ether as an ether monomer containing a hydroxyl functional group, and mixed with an inhibitor, an initiator, an organic solvent, stirred at a high speed of 500 rpm for 20-30min and reacted at room temperature for 3-5 hours to obtain a hydroxyl-containing polyether prepolymer;

[0020] B3: Mix 67.5% by weight of a hydroxyl-containing polyether prepolymer with 25% polymethyl acrylate microspheres containing tripolyphosphate and 7.5% aluminum tripolyacrylate particles. Add 10-20 drops of isocyanate and allow to react at 45-65°C for 6-8 hours. Pour the mixture into deionized water, stir rapidly, and allow it to foam. This yields a modified impact-resistant elastomer.

[0021] Specifically, the three impact protection layers, the energy dispersion layer and the buffer energy absorption layer are formed by hot pressing and bonding.

[0022] Specifically, the three impact protection layers, the energy dispersion layer and the buffer energy absorption layer are obtained by hot pressing and bonding at 0.75 MPa and 135° C. for 10 minutes.

[0023] Specifically, the crosslinking agent is 0.25% by mass of diethylene dicarboxylic anhydride, the cationic surfactant is 0.3% by mass of hexadecyltrimethylammonium bromide, the dispersant is 0.2% by mass of polyvinyl alcohol, and the initiator is 0.2% by mass of ammonium persulfate.

[0024] Specifically, the polymerization inhibitor is methyl methacrylate with a mass fraction of 2%, the initiator is ammonium persulfate with a mass fraction of 0.2%, and the organic solvent is dimethylformamide with a mass fraction of 40%.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention proposes an impact-resistant, buffering, and energy-absorbing composite structure, which has the following advantages:

[0027] 1. The present invention comprises a stacked combination of different materials to absorb and disperse impact energy at different levels, achieving a multi-level energy absorption effect.

[0028] 2. The present invention modifies the material to enhance the impact resistance of Kevlar; further increases the toughness of ultra-high molecular weight polyethylene fiber to prevent it from being penetrated by fragments and enhances the energy dispersion performance; obtains a modified buffering energy-absorbing elastomer with stronger fatigue resistance and temperature adaptability, maintains the buffering energy-absorbing characteristics in a wider temperature range, and has good durability.

[0029] 3. The present invention can block the penetration of bullets and fragments under high-speed impact and disperse the impact energy, thus meeting the protection needs of the human body in different working environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of impact-resistant, buffering and energy-absorbing structure;

[0031] 1- Impact protection layer; 2- Energy dispersion layer; 3- Buffer energy absorption layer; 4- Interlayer connection. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Specific embodiment 1

[0034] like Figure 1 As shown, an impact-resistant, buffering, and energy-absorbing composite structure specifically includes an impact protection layer 1, an energy dispersion layer 2, and a buffering, energy-absorbing layer 3; wherein the impact-resistant, buffering, and energy-absorbing composite structure is formed by hot pressing by bonding three protection layers 1, one dispersion layer 2, and one buffering, energy-absorbing layer 3, and the hot pressing bonding conditions are 0.75 MPa and pressing at 135°C for 10 minutes.

[0035] Among them, the impact protection layer 1 uses Kevlar fiber doped with methyldiphenylsilane modified polyurea, which has the function of resisting fragment penetration; the energy dispersion layer 2 uses modified ultra-high molecular weight polyethylene fiber, which enhances the toughness of the fiber and further disperses the impact energy; the modified ultra-high molecular weight polyethylene fiber is obtained by blending doped with methyldiphenylsilane modified polyurea; the buffering energy absorption layer 3 uses a buffering energy absorption elastomer doped with polymethyl acrylate microelements and aluminum tripolyphosphate particles; the buffering energy absorption elastomer not only exhibits good buffering energy absorption effect at room temperature and low temperature, but also can maintain good buffering energy absorption characteristics in high temperature environment.

[0036] The three-layer structure reasonably disperses the impact energy, which not only has the effect of resisting fragment penetration, but also disperses the energy and has a buffering and energy-absorbing effect; the impact protection layer can effectively resist the penetration of fragments and resist direct damage from fragments; the energy dispersion layer relies on its high toughness to further prevent fragment penetration, and disperses energy through deformation to avoid energy concentration at one point; the buffering and energy-absorbing layer can not only absorb most of the residual impact energy, but also effectively reduce the back convexity of the structure, which is suitable for protecting the human body against blunt impact injuries.

[0037] It should be noted that the steps for making the methyldiphenylsilane-modified polyurea-doped Kevlar fiber used in the impact protection layer 1 are as follows:

[0038] S1: Mix 40% by mass of methyldiphenylsilane (90% purity) with 60% of ethylenediamine, an amine compound used for synthesizing polyurea, at 40-50°C. Stir for 10-20 minutes, and let stand for 2-3 hours to obtain an amine compound containing a methyldiphenylsilane skeleton. This compound will then react with an isocyanate semi-prepolymer to obtain methyldiphenylsilane-modified polyurea (A).

[0039] S2: To achieve better impregnation, a 90% by mass ratio of aliphatic amine curing agent and 10% by mass of methyldiphenylsilane-modified polyurea (A) were mixed and stirred at 300 rpm for 30 minutes, then ultrasonically treated for 10 minutes, and finally dried under vacuum for 90 minutes. After ultrasonic treatment and drying, the mixture was used to soak Kevlar fibers.

[0040] S3: After soaking for 30 minutes and drying for 72 hours, the modified Kevlar fiber fabric can be obtained.

[0041] It should be noted that the modified ultra-high molecular weight polyethylene fiber used in the energy dissipation layer 2 is prepared as follows:

[0042] A1: Combine 10% methyldiphenylsilane and 90% epoxy resin, stir at 500 rpm for 30 minutes, and then ultrasonicate for 10 minutes. Then, add an aliphatic amine curing agent to the mixture at a 10:1 mass ratio, stir at 500 rpm for 30 minutes, and then ultrasonicate for 10 minutes to obtain a resin-based solution.

[0043] A2: The resin-based solution is mixed with the ultra-high molecular weight polyethylene obtained after hot melting at a mass ratio of 1:25, stirred thoroughly, and cooled to obtain a modified ultra-high molecular weight polyethylene. This modified material is then mixed with decalin at 145-165°C, stirred thoroughly, and cooled to obtain a modified material for preparing ultra-high molecular weight polyethylene fibers.

[0044] It should be noted that the steps for preparing the doped polymethyl acrylate micro-elements and aluminum tripolyphosphate particles in the buffer energy absorbing layer 3 are as follows:

[0045] B1: Methyl acrylate monomer, 0.25% by mass of diethylene glycol dicarboxylic anhydride, 0.3% by mass of cetyltrimethylammonium bromide, and 0.2% by mass of polyvinyl alcohol were mixed in a mass ratio of 69% methyl acrylate monomer, 20.5% by mass of diethylene glycol dicarboxylic anhydride, 5.5% by mass of cetyltrimethylammonium bromide, and 5% by mass of polyvinyl alcohol. Stir for 15 minutes using a high-speed blender. Then, using 0.2% by mass of ammonium persulfate as an initiator and controlling the temperature at 55°C, the reaction was allowed to proceed for 3-4 hours to produce polymethyl acrylate microelements.

[0046] B2: Ethylene glycol methyl ether was used as an ether monomer containing a hydroxyl functional group and mixed with 2% methyl methacrylate, 0.2% ammonium persulfate, and 40% dimethylformamide. After high-speed stirring for 25 minutes, the mixture was reacted at room temperature for 4 hours to obtain a polyether prepolymer containing a hydroxyl group.

[0047] B3: Mix a polyether prepolymer containing hydroxyl groups with a 30% by mass fraction of polymethyl acrylate microsphere units and a 10% by mass fraction of aluminum tripolyphosphate particle solution, add isocyanate dropwise, and place it at 50°C to react for 7 hours. Then pour it into deionized water and stir it rapidly, and then let it stand for foaming to finally obtain a modified impact-resistant, cushioning and energy-absorbing material.

[0048] The following is a ballistic impact test demonstrating the impact-resistant, cushioning, and energy-absorbing composite structure. The composite protective structure used in this invention (Condition 3) significantly reduced the depth of structural indentation and prevented penetration, ensuring efficient energy absorption. Under the impact of a 1.1g fragment at 300m / s, the indentation depth of the modified Kevlar / modified ultra-high molecular weight polyethylene / modified cushioning and energy-absorbing structure was reduced by 75.62% compared to the unmodified structure using EVA foam as the buffer layer (Condition 2). Energy absorption efficiency was increased by 11.46%, effectively preventing fragment penetration. It was also reduced by 65.16% compared to the unmodified structure using polyurethane elastomer (Condition 1).

[0049] .

[0050] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. An impact-resistant, buffering, and energy-absorbing composite structure, characterized by: The impact-resistant, buffering, and energy-absorbing composite structure sequentially comprises an impact protection layer (1), an energy dispersion layer (2), and a buffering and energy-absorbing layer (3); The impact protection layer (1) uses Kevlar fiber doped with methyldiphenylsilane-modified polyurea to resist fragment penetration; the production steps are as follows: S1: 40% by mass of 90% pure methyldiphenylsilane and 60% of ethylenediamine, an amine compound for synthesizing polyurea, are mixed at 40-50°C, stirred for 10-20 minutes, and allowed to stand for 2-3 hours to obtain an amine compound containing a methyldiphenylsilane skeleton; the amine compound is then used to react with an isocyanate semi-prepolymer to obtain a methyldiphenylsilane-modified polyurea; S2: To achieve better impregnation, 90% aliphatic amine curing agent and 10% methyldiphenylsilane-modified polyurea were mixed and stirred at 300 rpm for 30 minutes, followed by ultrasonic treatment for 10 minutes, and finally dried under vacuum for 90 minutes. S3: soaking the Kevlar fiber in the diluted methyldiphenylsilane-modified polyurea for 30 minutes and then drying it for 72 hours to obtain the modified Kevlar fiber; The energy dispersing layer (2) uses modified ultra-high molecular weight polyethylene fibers, which enhances the toughness of the fibers and plays a role in further dispersing the impact energy. The preparation steps are: A1: 10% methyldiphenylsilane and 90% epoxy resin were mixed, stirred at 500 rpm for 30 minutes, and then ultrasonically treated for 10 minutes. An aliphatic amine curing agent was then added to the mixed solution at a mass ratio of 10:1, stirred at 500 rpm for 30 minutes, and then ultrasonically treated for 10 minutes to obtain a resin-based solution. A2: The resin-based solution obtained in A1 is mixed with the ultra-high molecular weight polyethylene obtained after hot melting in a mass ratio of 1:25, and the mixture is thoroughly stirred and then cooled to obtain a modified ultra-high molecular weight polyethylene; The buffering energy absorbing layer (3) is made of a buffering energy absorbing elastomer doped with polymethyl acrylate microsphere units and aluminum tripolyphosphate particles; The preparation steps are as follows: B1: In a reaction vessel, a certain proportion of methyl acrylate monomer, a crosslinking agent, a cationic surfactant, and a dispersant are stirred at 500 rpm for 10-20 minutes, and then an initiator is added. The stirred solution is placed in an environment of 45-65°C to react for 3-4 hours to obtain polymethyl acrylate microsphere units; B2: Ethylene glycol methyl ether is used as an ether monomer containing a hydroxyl functional group, mixed with a polymerization inhibitor, an initiator, and an organic solvent, stirred at 500 rpm for 20-30 minutes, and then reacted at room temperature for 3-5 hours to obtain a polyether prepolymer containing a hydroxyl group; B3: Mix a polyether prepolymer containing 67.5% hydroxyl groups with 25% polymethyl acrylate microsphere units and 7.5% aluminum tripolyphosphate particle solution, add 10-20 drops of isocyanate, and place it in a 45-65°C environment to react for 6-8 hours. Then pour it into deionized water and stir it rapidly. Let it stand for foaming to finally obtain a modified impact-resistant elastomer material.

2. The impact-resistant, buffering, and energy-absorbing composite structure according to claim 1, characterized in that: The impact-resistant, buffering, and energy-absorbing composite structure is composed of three impact protection layers (1), an energy dispersion layer (2), and a buffering and energy-absorbing layer (3).

3. The impact-resistant, buffering, and energy-absorbing composite structure according to claim 2, wherein: The three impact protection layers (1), the energy dispersion layer (2) and the buffer energy absorption layer (3) are formed by hot pressing and bonding between the layers.

4. The impact-resistant, buffering, and energy-absorbing composite structure according to claim 3, characterized in that: The three impact protection layers (1), one energy dispersion layer (2) and one buffer energy absorption layer (3) are obtained by hot pressing and bonding at 0.75 MPa and 135° C. for 10 minutes.

5. The impact-resistant, buffering, and energy-absorbing composite structure according to claim 1, characterized in that: The polymerization inhibitor is methyl methacrylate with a mass fraction of 2%, the initiator is ammonium persulfate with a mass fraction of 0.2%, and the organic solvent is dimethylformamide with a mass fraction of 40%.

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