Anti-impact water area rescue helmet shell and preparation method and application thereof

Abstract

The invention relates to the technical field of water area rescue equipment, in particular to an anti-impact water area rescue helmet shell and a preparation method and application thereof.The preparation method comprises the steps that multiple layers of para-aramid fiber prepregs are laid and then pre-pressed to obtain a middle layer of the shell, carbon fiber prepregs are laid on the two faces of the middle layer, and then the shell is obtained. And finally pressing to obtain the shell. The shell is bonded with one face of the foam buffer layer, the other face of the foam buffer layer is attached to the closed-cell structure lining, and the helmet shell is obtained. The pre-pressing temperature ranges from 90 DEG C to 150 DEG C, the pre-pressing pressure ranges from 0.3 Mpa to 0.7 Mpa, and the pre-pressing time ranges from 7 minutes to 15 minutes. The final pressing temperature ranges from 80 DEG C to 120 DEG C, the final pressing pressure ranges from 0.7 Mpa to 1.5 Mpa, and the final pressing time ranges from 15 minutes to 20 minutes. When the helmet shell is applied to the water area rescue helmet, the requirements of light weight, high impact resistance, effective buoyancy and long-term use sanitation can be met at the same time.

Description

Technical Field

[0001] This invention relates to an impact-resistant water rescue helmet shell, its manufacturing method, and its application, belonging to the field of water rescue equipment technology. Background Technology

[0002] Water rescue helmets are crucial protective equipment for ensuring the head safety of water rescuers. Compared to land environments, water rescues often face more complex mechanical conditions: water currents not only increase the risk of rescuers becoming trapped or impacted, but also provide additional kinetic energy to suspended or floating debris (such as broken wood, rocks, and hard floating objects), thus posing a significant threat to the rescuer's head. Therefore, an ideal water rescue helmet must simultaneously meet multiple requirements, including strong impact resistance, sufficient buoyancy to reduce the risk of drowning, and lightweight construction to avoid strain on the neck and restriction of movement.

[0003] Currently, traditional water rescue helmets often have several design limitations. First, in terms of shell manufacturing, they are mostly made from single materials such as ABS engineering plastics or carbon fiber composites. While these materials achieve a certain degree of lightweighting, their impact resistance is still insufficient, especially under repeated, multi-angle impact conditions. Due to the inherent mechanical properties of these materials, significantly improving impact resistance through the optimization of a single material without substantially increasing the overall weight of the helmet presents a significant technical bottleneck.

[0004] Secondly, in terms of buffer layer design, most products use closed-cell polystyrene foam (EPS) as the main buffer material to maintain necessary buoyancy. EPS has advantages such as being lightweight, having low water absorption, and being easy to mold, but its energy absorption efficiency is limited. When dealing with high-intensity impacts, the buffering effect is often not ideal, making it difficult to further optimize the attenuation and dispersion of impact force while ensuring buoyancy.

[0005] Furthermore, the inner lining of helmets is typically made of traditional sponge or similar soft, porous materials. These materials easily absorb and retain moisture during actual use, causing the lining to remain damp for extended periods. This not only affects wearing comfort but also makes the helmet more susceptible to the growth of bacteria, mold, and other microorganisms, producing unpleasant odors and potentially causing hygiene problems, adversely affecting the health of rescue personnel and the long-term usability of the equipment.

[0006] In summary, existing water rescue helmets have not yet adequately balanced multiple requirements such as lightweight, high impact resistance, effective buoyancy, and long-term hygiene in terms of material selection and structural design. Their overall protective performance and user experience still need further improvement. Summary of the Invention

[0007] This invention addresses the shortcomings of existing technologies by providing an impact-resistant water rescue helmet shell, its manufacturing method, and its application. The helmet shell, when used in water rescue helmets, can simultaneously meet the requirements of lightweight, high impact resistance, effective buoyancy, and long-term hygiene.

[0008] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: a method for preparing an impact-resistant water rescue helmet shell, wherein the preparation method is as follows: S1. Preparation of the outer shell: After laying multiple layers of para-aramid fiber prepreg, the middle layer of the shell is obtained by pre-pressing. Then, carbon fiber prepreg is laid on both sides of the middle layer and finally pressed to obtain the shell. S2. Preparation of the helmet shell: The outer shell is bonded to one side of the foam cushioning layer, and the other side of the foam cushioning layer is bonded to the closed-cell structure liner to obtain the helmet shell.

[0009] Furthermore, in step S1, 3-5 layers of para-aramid fiber prepreg are laid and pre-pressed to obtain an intermediate layer, with each layer of para-aramid fiber prepreg being laid alternately at an angle of 40°-50°.

[0010] Furthermore, in step S1, the adhesive content of the para-aramid fiber prepreg is 15-30%, and the adhesive content of the carbon fiber prepreg is 25-40%.

[0011] Furthermore, in step S1, the pre-compression temperature is 90-150℃, the pre-compression pressure is 0.3-0.7 MPa, and the pre-compression time is 7-15 minutes.

[0012] Furthermore, in step S1, after pre-pressing, the carbon fiber prepreg is laid at 45-55℃, the final pressing temperature is 80-120℃, the final pressing pressure is 0.7-1.5 MPa, and the final pressing time is 15-20 minutes.

[0013] Furthermore, in step S1, the pre-pressing temperature is 10-30°C higher than the final pressing temperature; the final pressing pressure is higher than the pre-pressing pressure.

[0014] Furthermore, the buffer layer material is at least one of closed-cell EPP foam and closed-cell EPS foam.

[0015] Furthermore, the lining is EVA closed-cell foam.

[0016] The present invention also discloses an impact-resistant water rescue helmet shell, which is prepared by the preparation method described in the present invention.

[0017] The present invention also discloses the application of an impact-resistant water rescue helmet shell, which is used in a water rescue helmet.

[0018] The beneficial effects of this invention are: The gradient shell design significantly enhances impact and puncture resistance, while the optimized internal dual-buffer material combination effectively absorbs impact acceleration while maintaining buoyancy, achieving a lightweight and multi-functional protective integration. Furthermore, the phased curing process of pre-pressing and final pressing effectively avoids helmet wrinkles and glue gaps between aramid / carbon fiber heterogeneous layers, ensuring product structural integrity and performance reliability.

[0019] This invention achieves a "rigid-flexible-rigid" mechanical gradient in the shell design of a water rescue helmet through a gradient sandwich layering method, enhancing its impact resistance. Furthermore, a dual-density buffer layer design further enhances impact resistance while maintaining helmet rigidity. This improves the helmet's protective performance without significantly increasing its weight.

[0020] In the impact-resistant water rescue helmet shell of this invention, the carbon fiber of the outer shell can improve the overall rigidity, and the para-aramid fiber of the middle layer can optimize stress distribution and fully absorb energy. In the preparation method, by reasonably controlling the process conditions of pre-pressing and final pressing, it is beneficial to the interlayer bonding while avoiding wrinkle problems, so that the final shell is lightweight, supportive, and has higher impact resistance. The buffer layer adopts an EPP and EPS dual-density structure, which effectively achieves high impact resistance while ensuring support. The EVA lining has low water absorption and is easy to clean. The combination of these technical features makes the helmet shell more suitable for application in water rescue helmets. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the water rescue helmet described in this invention. Detailed Implementation

[0022] The specific embodiments of the present invention will be described in detail below. The present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used is for describing particular embodiments only and is not intended to limit the invention.

[0024] A method for preparing an impact-resistant water rescue helmet shell, the method comprising: S1. Preparation of the outer shell: After laying multiple layers of para-aramid fiber prepreg, the middle layer of the shell is obtained by pre-pressing. Then, carbon fiber prepreg is laid on both sides of the middle layer and finally pressed to obtain the shell. S2. Preparation of the helmet shell: The outer shell is bonded to one side of the foam cushioning layer, and the other side of the foam cushioning layer is bonded to the closed-cell structure liner to obtain the helmet shell.

[0025] Specifically, in step S1, 3-5 layers of para-aramid fiber prepreg are laid and pre-pressed to obtain an intermediate layer, with each layer of para-aramid fiber prepreg being laid alternately at an angle of 40°-50°.

[0026] More specifically, in step S1, in the outer shell structure, the carbon fiber prepreg on both sides of the middle layer is laid in a symmetrical manner, and there are 1-2 layers of carbon fiber prepreg on each side of the middle layer.

[0027] Preferably, in step S1, the carbon fiber prepreg on both sides of the middle layer of the outer shell structure is laid symmetrically, with one layer of carbon fiber prepreg on each side of the middle layer. This satisfies the impact resistance requirement while ensuring lightweight design.

[0028] Specifically, in step S1, the adhesive content of the para-aramid fiber prepreg is 15-30%, and the lower adhesive content can significantly reduce the mass of the shell; the adhesive content of the carbon fiber prepreg is 25-40%, which can ensure the full bonding of the para-aramid fiber and carbon fiber heterogeneous interface and prevent the phenomenon of insufficient adhesive between heterogeneous layers.

[0029] Specifically, in step S1, the pre-compression temperature is 90-150℃. A higher compression temperature allows the resin to have higher fluidity, resulting in a more uniform and full composite material with a lower resin content. The pre-compression pressure is 0.3-0.7 MPa, which balances the fluidity of the resin with curing. The pre-compression time is 7-15 minutes, ensuring that the intermediate layer is fully compressed.

[0030] More specifically, during the pre-compression process, when the temperature is relatively high, a relatively low pressure condition should be selected; when the temperature is relatively low, a relatively high pressure condition should be selected.

[0031] More preferably, adjusting the pressure and temperature according to the following relationship in actual production is more conducive to obtaining high-performance products: P1=p1±0.03, p1=-0.0062T1+1.24, where P1 is the pre-compression pressure in MPa and T1 is the pre-compression temperature in °C.

[0032] Specifically, in step S1, after pre-pressing, the carbon fiber prepreg is laid at 45-55℃ to maintain a certain temperature, preventing the resin from fully curing, which is beneficial for the subsequent bonding of aramid and carbon fiber. The final pressing temperature is 80-120℃, the final pressing pressure is 0.7-1.5 MPa, and the final pressing time is 15-20 minutes, which facilitates sufficient resin exchange between the heterogeneous layers, resulting in a better heterogeneous layer bonding effect.

[0033] More specifically, during the final pressing process, when the temperature is relatively high, a relatively low pressure condition is selected; when the temperature is relatively low, a relatively high pressure condition is selected.

[0034] More preferably, adjusting the pressure and temperature according to the following relationship in actual production is more conducive to obtaining high-performance products: P2=p2±0.03, p2=-0.02T2+3.1, where P2 is the final pressing pressure in MPa and T2 is the final pressing temperature in °C.

[0035] Specifically, in step S1, the pre-pressing temperature is 10-30°C higher than the final pressing temperature; the temperature difference between the pre-pressing temperature and the final pressing temperature can ensure that the layers in the shell are fully bonded while ensuring the flatness between the carbon fiber prepreg and the para-aramid fiber prepreg, reducing the risk of wrinkles.

[0036] Specifically, the final pressing pressure is higher than the pre-pressing pressure. The higher final pressure compared to the pre-pressing pressure makes it easier to achieve the predetermined thickness and reduces interlayer wrinkles at the heterogeneous interface (aramid and carbon fiber have different elongation at break, which may cause wrinkles under lower pressure).

[0037] Specifically, the buffer layer material is at least one of closed-cell EPP foam and closed-cell EPS foam.

[0038] Preferably, the buffer layer is a combination of closed-cell EPP foam and closed-cell EPS foam, wherein the closed-cell EPP foam is hemispherical and located at the top, and the closed-cell EPS foam is annular and located at the bottom, as shown in the following figure. Figure 1 As shown.

[0039] The closed-cell EPP foam after foaming has a density of 25-50 kg / m³. 3 The density of closed-cell EPS foam after foaming is 30-80 kg / m³. 3 .

[0040] The outer shell and the buffer layer are bonded together with polyurethane adhesive.

[0041] More specifically, closed-cell EPP foam is directly foamed and molded into the shape required for the helmet in a mold, and closed-cell EPS foam is directly foamed and molded into the shape required for the helmet in a mold.

[0042] More specifically, a polyurethane adhesive (model 3M 2214) is evenly applied to the bonding surface of the outer shell, and the buffer layer is attached. The mixture is then cured at 60°C under a pressure of 0.3 MPa for 30 minutes to achieve bonding between the outer shell and the buffer layer.

[0043] Specifically, the lining is made of EVA closed-cell foam (low water absorption). After the EVA closed-cell foam lining is hot-pressed, it is fixed to the inside of the buffer layer with Velcro.

[0044] An impact-resistant water rescue helmet shell, wherein the helmet shell is prepared by the preparation method described in this invention.

[0045] An application of an impact-resistant water rescue helmet shell, which is used in water rescue helmets. A chin strap and a modular system commonly used in helmets can be installed on the helmet shell. Suitable through-holes are provided on the shell (to prevent water from pooling in the helmet during underwater use), ultimately forming a finished water rescue helmet.

[0046] For the chin strap, aramid webbing (tensile strength > 60MPa) can be used, connected to anchor points on both sides of the housing with screws. Additionally, 6061 aluminum alloy nuts can be pre-embedded on both sides of the housing as guide rail bases, and the guide rails can be fixed with M3 countersunk screws to achieve modular system installation.

[0047] Example 1 A method for preparing a multi-layer composite impact-resistant water rescue helmet includes the following steps: (1) Preparation of the outer shell: Materials: The outer / inner layer uses T300 grade carbon fiber prepreg (plain weave fabric, 300g / m², epoxy resin content 38%, of which the epoxy resin is Guangxuan New Materials' 315K); the middle layer uses para-aramid prepreg (aramid fiber 1500D, plain weave fabric, 300g / m², epoxy resin content 30%, of which the epoxy resin is Guangxuan New Materials' 315K).

[0048] Three layers of para-aramid prepreg are laid alternately at a 45° angle, placed in a mold, and pre-pressed to obtain the middle layer; the pre-pressing temperature is 120℃, the pressure is 0.5Mpa, and the pre-pressing time is 10min. A layer of carbon fiber prepreg is laid on both sides of the middle layer, and then placed in a mold for final pressing to obtain the outer shell; the final pressing temperature is 100℃, the pressure is 1.1Mpa, and the final pressing time is 18min.

[0049] (2) Preparation of the buffer layer: EPP foam: density 35kg / m³, closed cell rate >95%, thickness 15mm, directly foamed and molded in a mold to the shape required in the helmet.

[0050] EPS foam: density 50kg / m³, closed cell rate >90%, thickness 15mm, directly foamed and molded in a mold to the shape required for helmets.

[0051] The closed-cell EPP foam is set in a hemispherical shape at the top, while the closed-cell EPS foam is annular at the bottom.

[0052] (3) Bonding between the outer shell and the buffer layer: Apply polyurethane adhesive (model 3M 2214) evenly to the bonding surface of the shell, attach the EPP buffer layer and EPS buffer layer, apply pressure of 0.3MPa at 60°C, and cure for 30 minutes.

[0053] (4) Assembly of lining and chin strap: Lining: EVA closed-cell foam (density 200kg / m³) 3 (Water absorption rate <8%), after hot pressing, it is fixed to the inside of the buffer layer with Velcro to obtain the final helmet shell.

[0054] Jawline strap: Aramid webbing (tensile strength > 60MPa), connected to anchor points on both sides of the shell by screws.

[0055] (3) Modular system integration: 6061 aluminum alloy nuts are pre-embedded on both sides of the shell as guide rail bases, and the guide rails are fixed by M3 countersunk screws to obtain a water rescue helmet.

[0056] Example 2 A method for preparing a multi-layer composite impact-resistant water rescue helmet includes the following steps: (1) Preparation of the outer shell: Materials: The outer / inner layer uses T700 grade carbon fiber prepreg (plain weave fabric, 300g / m², epoxy resin content 40%, of which the epoxy resin is Guangxuan New Materials' 315K); the middle layer uses para-aramid prepreg (aramid fiber 1500D, plain weave fabric, 300g / m², epoxy resin content 30%, of which the epoxy resin is Guangxuan New Materials' 315K).

[0057] Five layers of para-aramid prepreg are laid alternately at a 45° angle, placed in a mold, and pre-pressed to obtain the intermediate layer; the pre-pressing temperature is 150℃, the pressure is 0.3Mpa, and the pre-pressing time is 15min.

[0058] A layer of carbon fiber prepreg is laid on both sides of the middle layer, and then placed in a mold for final pressing to obtain the outer shell; the final pressing temperature is 120℃, the pressure is 0.7Mpa, and the final pressing time is 15min.

[0059] (2) Preparation of the buffer layer: EPP foam: density 25kg / m³, closed cell rate >95%, thickness 15mm, directly foamed and molded in a mold to the shape required in the helmet.

[0060] EPS foam: density 60kg / m³, closed cell rate >90%, thickness 15mm, directly foamed and molded in a mold to the shape required for helmets.

[0061] The closed-cell EPP foam is set in a hemispherical shape at the top, while the closed-cell EPS foam is annular at the bottom.

[0062] (3) Bonding between the outer shell and the buffer layer: Apply polyurethane adhesive (model 3M 2214) evenly to the bonding surface of the shell, attach the EPP buffer layer and EPS buffer layer, apply pressure of 0.3MPa at 60°C, and cure for 30 minutes.

[0063] (4) Assembly of lining and chin strap: Lining: EVA closed-cell foam (density 200kg / m³) 3 (Water absorption rate <8%), after hot pressing, it is fixed to the inside of the buffer layer with Velcro to obtain the final helmet shell.

[0064] Jawline strap: Aramid webbing (tensile strength > 60MPa), connected to anchor points on both sides of the shell by screws.

[0065] (3) Modular system integration: 6061 aluminum alloy nuts are pre-embedded on both sides of the shell as guide rail bases, and the guide rails are fixed by M3 countersunk screws to obtain a water rescue helmet.

[0066] Example 3 A method for preparing a multi-layer composite impact-resistant water rescue helmet includes the following steps: (1) Preparation of the outer shell: Materials: The outer / inner layer uses T700 grade carbon fiber prepreg (plain weave fabric, 300g / m², epoxy resin content 25%, of which the epoxy resin is Guangxuan New Materials' 315K); the middle layer uses para-aramid prepreg (aramid fiber 1500D, plain weave fabric, 300g / m², epoxy resin content 15%, of which the epoxy resin is Guangxuan New Materials' 315K).

[0067] Five layers of para-aramid prepreg are laid alternately at a 40° angle, placed in a mold, and pre-pressed to obtain the intermediate layer; the pre-pressing temperature is 90℃, the pressure is 0.7Mpa, and the pre-pressing time is 12min.

[0068] Two layers of carbon fiber prepreg are laid on both sides of the middle layer, and then placed in a mold for final pressing to obtain the outer shell; the final pressing temperature is 80℃, the pressure is 1.5Mpa, and the final pressing time is 20min.

[0069] (2) Preparation of the buffer layer: EPP foam: density 25kg / m³, closed cell rate >95%, thickness 15mm, directly foamed and molded in a mold to the shape required in the helmet.

[0070] EPS foam: density 60kg / m³, closed cell rate >90%, thickness 15mm, directly foamed and molded in a mold to the shape required for helmets.

[0071] The closed-cell EPP foam is set in a hemispherical shape at the top, while the closed-cell EPS foam is annular at the bottom.

[0072] (3) Bonding between the outer shell and the buffer layer: Apply polyurethane adhesive (model 3M 2214) evenly to the bonding surface of the shell, attach the EPP buffer layer and EPS buffer layer, apply pressure of 0.3MPa at 60°C, and cure for 30 minutes.

[0073] (4) Assembly of lining and chin strap: Lining: EVA closed-cell foam (density 200kg / m³) 3 (Water absorption rate <8%), after hot pressing, it is fixed to the inside of the buffer layer with Velcro to obtain the final helmet shell.

[0074] Jawline strap: Aramid webbing (tensile strength > 60MPa), connected to anchor points on both sides of the shell by screws.

[0075] (3) Modular system integration: 6061 aluminum alloy nuts are pre-embedded on both sides of the shell as guide rail bases, and the guide rails are fixed by M3 countersunk screws to obtain a water rescue helmet.

[0076] Example 4 A method for preparing a multi-layer composite impact-resistant water rescue helmet includes the following steps: (1) Preparation of the outer shell: Materials: The outer / inner layer uses T300 grade carbon fiber prepreg (plain weave fabric, 300g / m², epoxy resin content 38%, of which the epoxy resin is Guangxuan New Materials' 315K); the middle layer uses para-aramid prepreg (aramid fiber 1500D, plain weave fabric, 300g / m², epoxy resin content 30%, of which the epoxy resin is Guangxuan New Materials' 315K).

[0077] Three layers of para-aramid prepreg are laid alternately at a 45° angle, placed in a mold, and pre-pressed to obtain the middle layer; the pre-pressing temperature is 120℃, the pressure is 0.5Mpa, and the pre-pressing time is 10min. A layer of carbon fiber prepreg is laid on both sides of the middle layer, and then placed in a mold for final pressing to obtain the outer shell; the final pressing temperature is 100℃, the pressure is 1.1Mpa, and the final pressing time is 18min.

[0078] (2) Preparation of the buffer layer: EPS foam: density 50kg / m³, closed-cell rate >90%, thickness 15mm, directly foamed and molded in a mold to the shape required in the helmet. The entire cushioning layer is made of closed-cell EPS foam.

[0079] (3) Bonding between the outer shell and the buffer layer: Apply polyurethane adhesive (model 3M 2214) evenly to the bonding surface of the shell, attach the EPP buffer layer, apply pressure of 0.3MPa at 60°C, and cure for 30 minutes.

[0080] (4) Assembly of lining and chin strap: Lining: EVA closed-cell foam (density 200kg / m³) 3 (Water absorption rate <8%), after hot pressing, it is fixed to the inside of the buffer layer with Velcro to obtain the final helmet shell.

[0081] Jawline strap: Aramid webbing (tensile strength > 60MPa), connected to anchor points on both sides of the shell by screws.

[0082] (3) Modular system integration: 6061 aluminum alloy nuts are pre-embedded on both sides of the shell as guide rail bases, and the guide rails are fixed by M3 countersunk screws to obtain a water rescue helmet.

[0083] Comparative Example 1 The water rescue helmet was prepared using the same method as in Example 1, except that: in step (1) of Comparative Example 1, no para-aramid prepreg was used, and all five layers were made of T300 carbon fiber prepreg. Other process conditions were the same as in Example 1.

[0084] Comparative Example 2 The water rescue helmet was prepared using the same method as in Example 1, except that in step (1) of Comparative Example 2, no pre-pressing operation was performed. Instead, carbon fiber prepreg was directly laid in the mold, followed by three layers of para-aramid prepreg laid alternately at a 45° angle, and then another layer of carbon fiber prepreg was laid to form a five-layer structure. After pressing, the pressing temperature was 120°C, the pressure was 0.7 MPa, and the pressing time was 30 min. Other process conditions were the same as in Example 1.

[0085] Comparative Example 3 The water rescue helmet was prepared using the same method as in Example 1, except that the final pressing temperature in Comparative Example 3 was 150°C (higher than the temperature limit of this invention), and the other process conditions were the same as in Example 1.

[0086] Comparative Example 4 The water rescue helmet was prepared using the same method as in Example 1, except that in this Comparative Example 4, the final pressing temperature was adjusted to 120°C (the same as the pre-pressing temperature conditions), and other process conditions were the same as in Example 1.

[0087] Comparative Example 5 The water rescue helmet was prepared using the same method as in Example 2, except that in this Comparative Example 5, the pre-pressing temperature was adjusted to 120°C (the same as the final pressing temperature), and other process conditions were the same as in Example 2.

[0088] Comparative Example 6 The water rescue helmet was prepared using the same method as in Example 2, except that in this Comparative Example 6, the final pressing temperature was adjusted to 90°C (i.e., the temperature difference between the pre-pressing temperature and the final pressing temperature is higher than 30°C), and other process conditions were the same as in Example 2.

[0089] Comparative Example 7 SY-TK type water rescue helmet.

[0090] The water rescue helmets prepared in the above embodiments and comparative examples were subjected to performance tests in accordance with the methods of XF44-2015 "Fire Helmets". The specific test results are shown in Table 1 below.

[0091] Table 1 Performance Test Results

[0092] The results above show that the helmet shells and water rescue helmets prepared using the method described in Examples 1-4 achieve a "rigid-flexible-rigid" mechanical gradient in the helmet shell design through a gradient sandwich layering method, enhancing impact resistance. Furthermore, the dual-density buffer layer design ensures helmet rigidity while enhancing impact resistance. This improves the helmet's protective performance without significantly increasing its weight. Compared to traditional SY-TK type (ABS) water helmets, it exhibits significant advantages in both impact energy absorption and puncture resistance. A comparison of the results from Examples 3 and 2 shows that as the number of aramid layers increases, the helmet's performance further improves, but the overall weight also increases. Additionally, a comparison between Example 4 and Example 1 shows that the dual-material buffer layer structure has a stronger energy absorption effect than the single-material buffer layer structure.

[0093] The comparison of the experimental results of Comparative Example 1 and Example 1 shows that the aramid water rescue helmet with a sandwich multilayer structure in Example 1 has better top impact energy absorption, impact acceleration resistance and puncture resistance than the pure carbon fiber water rescue helmet in Comparative Example 1, while also having a lower overall helmet weight.

[0094] The comparison of the experimental results of Comparative Example 2 and Example 1 shows that if the pre-pressing and final pressing steps are not set separately when preparing the shell, the impact energy absorption effect will decrease. This is because a single pressing condition cannot allow both carbon fiber and aramid fiber to flow and solidify fully, and there may also be a lack of adhesive between the heterogeneous layers.

[0095] The comparison of the experimental results of Comparative Example 3 and Example 1 shows that if the final pressing temperature is too high when preparing the shell, the impact acceleration value will increase sharply because some resin is thermally degraded, resulting in a resin-deficient area that loses its ability to transfer load.

[0096] The comparison of experimental results between Comparative Example 4 and Example 1, and the comparison of experimental results between Comparative Document 5 and Example 2, shows that if the temperature conditions for pre-pressing and final pressing are the same when preparing the shell, the impact resistance of the helmet will decrease. This is because in a composite material mold with a complex curved surface like a helmet, maintaining a high temperature will reduce the resin viscosity, cause the fibers to slip randomly, and thus cause wrinkles.

[0097] A comparison of the experimental results from Comparative Example 6 and Example 2 shows that if the temperature difference between pre-pressing and final pressing is too large during shell preparation, the impact energy absorption effect will be poor. This is because if the final pressing temperature is too low, the temperature drop will be too large, the curing reaction will be insufficient, and effective compaction cannot be achieved. Therefore, setting the pre-pressing temperature 10-30°C higher than the final pressing temperature is more conducive to obtaining a water rescue helmet with excellent overall performance.

[0098] In summary, this invention relates to an impact-resistant water rescue helmet based on multi-layer composite materials and its preparation method. By using a sandwich structure shell made of aramid and carbon fiber, supplemented with EPP and EPS foam cushioning layers, a water rescue helmet with high protective performance is prepared.

[0099] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are exhaustively listed. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0100] For those skilled in the art, various modifications and improvements can be made without departing from the concept of the present invention, and these modifications and improvements are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A method for preparing an impact-resistant water rescue helmet shell, characterized in that, The preparation method is as follows: S1. Preparation of the outer shell: After laying multiple layers of para-aramid fiber prepreg, the middle layer of the shell is obtained by pre-pressing. Then, carbon fiber prepreg is laid on both sides of the middle layer and finally pressed to obtain the shell. S2. Preparation of the helmet shell: The outer shell is bonded to one side of the foam cushioning layer, and the other side of the foam cushioning layer is bonded to the closed-cell structure liner to obtain the helmet shell.

2. The method for preparing an impact-resistant water rescue helmet shell according to claim 1, characterized in that, In step S1, 3-5 layers of para-aramid fiber prepreg are laid and pre-pressed to obtain an intermediate layer, with each layer of para-aramid fiber prepreg being laid alternately at an angle of 40°-50°.

3. The method for preparing an impact-resistant water rescue helmet shell according to claim 1, characterized in that, In step S1, the adhesive content of the para-aramid fiber prepreg is 15-30%, and the adhesive content of the carbon fiber prepreg is 25-40%.

4. The method for preparing an impact-resistant water rescue helmet shell according to claim 1, characterized in that, In step S1, the pre-compression temperature is 90-150℃, the pre-compression pressure is 0.3-0.7 MPa, and the pre-compression time is 7-15 minutes.

5. The method for preparing an impact-resistant water rescue helmet shell according to claim 1, characterized in that, In step S1, after pre-pressing, the carbon fiber prepreg is laid at 45-55℃, the final pressing temperature is 80-120℃, the final pressing pressure is 0.7-1.5 MPa, and the final pressing time is 15-20 minutes.

6. The method for preparing an impact-resistant water rescue helmet shell according to claim 1, characterized in that, In step S1, the pre-pressing temperature is 10-30°C higher than the final pressing temperature; the final pressing pressure is higher than the pre-pressing pressure.

7. The method for preparing an impact-resistant water rescue helmet shell according to claim 1, characterized in that, The buffer layer is made of at least one of closed-cell EPP foam and closed-cell EPS foam.

8. The method for preparing an impact-resistant water rescue helmet shell according to claim 1, characterized in that, The lining is EVA closed-cell foam.

9. An impact-resistant water rescue helmet shell, characterized in that, The helmet shell is prepared by any one of the preparation methods described in claims 1-8.

10. An application of the impact-resistant water rescue helmet shell according to claim 9, characterized in that, The helmet shell is used in water rescue helmets.

Images