Preparation method of PE bulletproof plate

Abstract

The invention discloses a preparation method of a PE bulletproof plate. The preparation method comprises the following steps: S1, preparing materials; s2, laminating and laying: pre-stretching or pre-heating the UHMWPE fiber non-woven cloth before laying by adopting a cross laying structure (1); (2) cleaning the mold, and laying a layer of demolding cloth; (3) a first layer of UHMWPE fiber non-woven cloth is laid, the fiber direction is set to be 0 degree, then a layer of resin film is laid, a second layer of UHMWPE fiber non-woven cloth is laid, the fiber direction is rotated by 90 degrees and is perpendicular to the first layer, and the steps are repeated; a multi-stage temperature-pressure curve is adopted in the hot press molding stage, the porosity can be effectively and remarkably reduced, the interlaminar shear strength (ILSS) is improved, the product size stability is extremely high, a cooling curve is designed according to the crystallization dynamic characteristics of resin during cooling, slow cooling is achieved in the crystallization temperature interval, and the product quality is improved. The resin is promoted to form a more perfect crystal structure with a more uniform size.

Description

Technical Field

[0001] This invention relates to the field of PE bulletproof technology, and more specifically, to a method for preparing PE bulletproof plates. Background Technology

[0002] PE plates, as reinforcement products for individual protective gear, are usually used in conjunction with bulletproof vests. Existing PE bulletproof plates are mainly composed of UHMWPE fiber nonwoven fabric, thermoplastic resin film, and bulletproof coating material. During preparation, these three materials are stacked in multiple layers and then hot-pressed to form the plate. However, the traditional hot-pressing process mainly adopts a high-temperature, high-pressure + cooling and shaping mode. Although mature, it has bottlenecks in terms of energy consumption, efficiency, performance limits, and product diversity. The single high-temperature, high-pressure method results in high product porosity and extremely poor product dimensional stability. At the same time, uniform cooling makes the crystal structure formed by the resin unstable, which easily increases the product warpage. Therefore, we propose a method for preparing PE bulletproof plates. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of existing technologies by proposing a method for preparing PE bulletproof plates.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a PE bulletproof plate, comprising the following steps: S1. Material preparation: Select UHMWPE fiber nonwoven fabric, thermoplastic resin film and encapsulation material, and modify them. S2, Layered Layup: Adopting a cross-layup structure (1) Before lay-up, the UHMWPE fiber nonwoven fabric is pre-stretched or preheated to flatten the fiber bundles in advance, reduce internal voids, and make it easier for the resin to impregnate later. (2) Clean the mold and lay down a layer of release cloth; (3) Lay the first layer of UHMWPE fiber nonwoven fabric with the fiber direction set at 0°, then lay a layer of resin film, and then lay the second layer of UHMWPE fiber nonwoven fabric with the fiber direction rotated 90° and perpendicular to the first layer. Repeat the above steps until all layers of nonwoven fabric and resin film are laid, and cover the top layer with a release cloth. S3. Hot pressing: Employing multi-stage temperature-pressure curves. (1) Stage 1: Low pressure, medium temperature. Increase the temperature from 0 to 90-110℃ at a rate greater than 10℃ / minute, stop heating, and maintain the constant temperature for 15-25 minutes. At the same time, increase the pressure to 15-20 MPa within 10 seconds to ensure uniform temperature transfer. The resin film will initially melt and begin to slowly wet the fiber bundles, expelling most of the air and avoiding the "airlock" phenomenon. (2) Stage 2: High pressure and high temperature. When the resin is completely melted and has the best fluidity, the temperature is raised to 140-160℃ within 10 minutes, and the pressure is uniformly increased to 25-40MPa. This is maintained for 35-60 minutes to allow the resin to completely penetrate between each fiber and achieve ultimate densification. (3) Stage 3: Gradual cooling and pressure holding. Cool the temperature to 120-140℃ within 2-4 minutes, maintain the pressure at 25-35MPa, keep the temperature constant for 5-7 minutes, then cool the temperature to 70-100℃ within 5-10 minutes, maintain the pressure at 25-35MPa, then cool the temperature to 40-60℃ within 5-10 minutes, maintain the pressure at 25-35MPa, and release the pressure and demold after it has completely cooled to room temperature.

[0005] S4. Post-processing: Using a waterjet cutter, the square plates are cut into ergonomic curved bulletproof plate shapes. As needed, a layer of polyurethane (PU) coating is sprayed or rolled onto the surface of the bulletproof plate to enhance its environmental adaptability.

[0006] Preferably, the pressure is set as follows: The material modification in step S1 includes: (1) Fiber: UHMWPE fiber is subjected to iontophoresis to enhance its interfacial bonding with resin; (2) Resin: Carbon nanotubes and graphene are added to the resin, and various thermoplastics are blended together.

[0007] Preferably, ultrasonic-assisted hot pressing is used in step S3, the second stage of hot pressing.

[0008] Preferably, the ultrasonic frequency is 20-28kHz, the power range is 1000-1500W, the amplitude is 15-25μm, the pulse mode is adopted, and the pulse period can be set to 1s on / 0.5s off.

[0009] Preferably, a portion of the UHMWPE layer is pre-formed into a tiny 3D structure and then composited with other flat layers.

[0010] The technical effects and advantages of this invention are as follows: 1. The present invention employs a multi-stage temperature-pressure curve in the hot pressing stage, which can effectively and significantly reduce porosity and improve interlaminar shear strength (ILSS), resulting in extremely high product dimensional stability. During cooling, a cooling curve is designed based on the crystallization kinetics of the resin, and the temperature is slowly reduced within the crystallization temperature range, promoting the formation of a more perfect and uniform crystal structure, greatly reducing internal stress, and thus reducing product warping and deformation.

[0011] 2. This invention adds ultrasonic-assisted hot pressing at the stage when the resin has just melted and the viscosity begins to decrease, which can significantly reduce the melt viscosity, allowing the resin to have better fluidity at lower temperatures and avoiding potential damage to the fibers from high temperatures; it improves wettability, strongly drives the resin into the fiber bundle, achieves super-strong wetting, saves energy and protects fiber performance, and the ultrasonic-assisted process shortens the hot pressing cycle and reduces energy consumption.

[0012] 3. This invention forms a unidirectional prepreg by unidirectionally arranging fibers and impregnating them with a special resin. Then, multiple layers of unidirectional prepreg are cross-stacked at 0° and 90°. The "0° / 90°" cross structure provides the key to isotropic protection performance. After high temperature and high pressure molding, the fibers in the final PE bulletproof plate can effectively disperse and absorb the impact kinetic energy of the bullet, achieving good bulletproof purpose. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0014] Example 1 A method for preparing a PE bulletproof plate includes the following steps: S1. Material preparation: Select UHMWPE fiber nonwoven fabric, thermoplastic resin film and encapsulation coating material, and modify them. (1) Fiber: Treat UHMWPE fiber with plasma to enhance its interfacial bonding with resin. (2) Resin: Carbon nanotubes and graphene are added to the resin, and various thermoplastics are blended together. S2. Determine the protection level and cut: Determine the number of layers of UHMWPE fiber nonwoven fabric required based on the target (e.g., NIJ Level III, Level IIIA). For example, Level IIIA requires about 20-30 layers, and Level III requires about 30-40 layers. After determining the number of layers, cut the UHMWPE fiber nonwoven fabric and resin film into square sheets that are slightly larger than the final product size. S3, Layered Layup: Employing a cross-layup structure (1) Before layup, the UHMWPE fiber nonwoven fabric is pre-stretched or preheated to flatten the fiber bundles in advance, reduce internal voids, and make it easier for subsequent resin to impregnate. Some UHMWPE layers are pre-formed into tiny 3D structures, which can be corrugated or dotted, and then combined with other flat layers. These 3D structures will produce controllable collapse when under pressure, which greatly improves energy absorption efficiency. (2) Clean the mold and lay down a layer of release cloth; (3) Lay the first layer of UHMWPE fiber nonwoven fabric with the fiber direction set at 0°, then lay a layer of resin film, and then lay the second layer of UHMWPE fiber nonwoven fabric with the fiber direction rotated 90° and perpendicular to the first layer. Repeat the above steps until all layers of nonwoven fabric and resin film are laid, and cover the top layer with a release cloth. S4. Hot pressing: Employing multi-stage temperature-pressure curves. (1) Stage 1: Low pressure, medium temperature. Increase the temperature from 0 to 90-110℃ at a rate greater than 10℃ / minute, stop heating, and maintain the constant temperature for 15-25 minutes. At the same time, increase the pressure to 15-20 MPa within 10 seconds to ensure uniform temperature transfer. The resin film will initially melt and begin to slowly wet the fiber bundles, expelling most of the air and avoiding the "airlock" phenomenon. (2) Stage 2: High pressure and high temperature. When the resin is completely melted and has the best fluidity, the temperature is raised to 140-160℃ within 10 minutes, and the pressure is uniformly increased to 25-40MPa and maintained for 35-60 minutes. At the same time, when the temperature reaches 130℃, ultrasonic-assisted hot pressing is used. The ultrasonic frequency is 20-28kHz, the power range is 1000-1500W, the amplitude is 15-25μm, and the pulse mode is used. The pulse period can be set to 1s on / 0.5s off. While performing traditional hot pressing, the ultrasonic vibration energy is introduced into the laminated material through the mold. The high-frequency vibration generates a microscopic "acoustic flow effect" and local thermal effect, so that the resin can completely penetrate between each fiber to achieve extreme densification. (3) Stage 3: Gradual cooling and pressure holding. Cool the temperature to 120-140℃ within 2-4 minutes, maintain the pressure at 25-35MPa, keep the temperature constant for 5-7 minutes, then cool the temperature to 70-100℃ within 5-10 minutes, maintain the pressure at 25-35MPa, then cool the temperature to 40-60℃ within 5-10 minutes, maintain the pressure at 25-35MPa, and release the pressure and demold after it has completely cooled to room temperature.

[0015] S5. Post-processing: Using a waterjet cutter, the square plates are cut into ergonomic curved bulletproof plate shapes. As needed, a layer of polyurethane (PU) coating is sprayed or rolled onto the surface of the bulletproof plate to enhance its environmental adaptability.

[0016] Example 2 A method for preparing a PE bulletproof plate includes the following steps: S1. Material Preparation: Select UHMWPE fiber nonwoven fabric, thermoplastic resin film, and encapsulation material, and modify them accordingly. (1) Fiber: UHMWPE fiber is subjected to iontophoresis to enhance its interfacial bonding with resin; (2) Resin: Carbon nanotubes and graphene are added to the resin, and various thermoplastics are blended together. S2. Determine the protection level and cut: Determine the number of layers of UHMWPE fiber nonwoven fabric required based on the target (e.g., NIJ Level III, Level IIIA). For example, Level IIIA requires about 20-30 layers, and Level III requires about 30-40 layers. After determining the number of layers, cut the UHMWPE fiber nonwoven fabric and resin film into square sheets that are slightly larger than the final product size. S3, Layered Layup: Employing a cross-layup structure (1) Before layup, the UHMWPE fiber nonwoven fabric is pre-stretched or preheated to flatten the fiber bundles in advance, reduce internal voids, and make it easier for subsequent resin to impregnate. Some UHMWPE layers are pre-formed into tiny 3D structures, which can be corrugated or dotted, and then combined with other flat layers. These 3D structures will produce controllable collapse when under pressure, which greatly improves energy absorption efficiency. (2) Clean the mold and lay down a layer of release cloth; (3) Lay the first layer of UHMWPE fiber nonwoven fabric with the fiber direction set at 0°, then lay a layer of resin film, and then lay the second layer of UHMWPE fiber nonwoven fabric with the fiber direction rotated 90° and perpendicular to the first layer. Repeat the above steps until all layers of nonwoven fabric and resin film are laid, and cover the top layer with a release cloth. S4. Hot pressing: Employing multi-stage temperature-pressure curves. (1) Stage 1: Low pressure, medium temperature. Increase the temperature from 0 to 98-108℃ at a rate of more than 10℃ / minute, stop heating, and maintain the constant temperature for 15-25 minutes. At the same time, increase the pressure to 15-20 MPa within 10 seconds to ensure uniform temperature transfer. The resin film will initially melt and begin to slowly wet the fiber bundles, expelling most of the air and avoiding the "airlock" phenomenon. (2) Stage 2: High pressure and high temperature. When the resin is completely melted and has the best fluidity, the temperature is raised to 150-160℃ within 10 minutes, and the pressure is uniformly increased to 25-40MPa and maintained for 35-60 minutes. At the same time, when the temperature reaches 130℃, ultrasonic-assisted hot pressing is used. The ultrasonic frequency is 20-28kHz, the power range is 1200-1500W, the amplitude is 16-24μm, and the pulse mode is used. The pulse period can be set to 1s on / 0.5s off. While performing traditional hot pressing, the ultrasonic vibration energy is introduced into the laminated material through the mold. The high-frequency vibration generates a microscopic "acoustic flow effect" and local thermal effect, so that the resin can completely penetrate between each fiber to achieve extreme densification. (3) Stage 3: Gradual cooling and pressure holding. Cool the temperature to 130-140℃ within 2-4 minutes, maintain the pressure at 25-35MPa, keep the temperature constant for 5-7 minutes, then cool the temperature to 70-90℃ within 5-10 minutes, maintain the pressure at 25-35MPa, then cool the temperature to 45-60℃ within 5-10 minutes, maintain the pressure at 25-35MPa, and release the pressure and demold after it has completely cooled to room temperature.

[0017] S5. Post-processing: Using a waterjet cutter, the square plates are cut into ergonomic curved bulletproof plate shapes. As needed, a layer of polyurethane (PU) coating is sprayed or rolled onto the surface of the bulletproof plate to enhance its environmental adaptability.

[0018] Example 3 A method for preparing a PE bulletproof plate includes the following steps: S1. Material preparation: Select UHMWPE fiber nonwoven fabric, thermoplastic resin film and encapsulation coating material, and modify them. (1) Fiber: Treat UHMWPE fiber with plasma to enhance its interfacial bonding with resin. (2) Resin: Carbon nanotubes and graphene are added to the resin, and various thermoplastics are blended together. S2. Determine the protection level and cut: Determine the number of layers of UHMWPE fiber nonwoven fabric required based on the target (e.g., NIJ Level III, Level IIIA). For example, Level IIIA requires about 20-30 layers, and Level III requires about 30-40 layers. After determining the number of layers, cut the UHMWPE fiber nonwoven fabric and resin film into square sheets that are slightly larger than the final product size. S3, Layered Layup: Employing a cross-layup structure (1) Before layup, the UHMWPE fiber nonwoven fabric is pre-stretched or preheated to flatten the fiber bundles in advance, reduce internal voids, and make it easier for subsequent resin to impregnate. Some UHMWPE layers are pre-formed into tiny 3D structures, which can be corrugated or dotted, and then combined with other flat layers. These 3D structures will produce controllable collapse when under pressure, which greatly improves energy absorption efficiency. (2) Clean the mold and lay down a layer of release cloth; (3) Lay the first layer of UHMWPE fiber nonwoven fabric with the fiber direction set at 0°, then lay a layer of resin film, and then lay the second layer of UHMWPE fiber nonwoven fabric with the fiber direction rotated 90° and perpendicular to the first layer. Repeat the above steps until all layers of nonwoven fabric and resin film are laid, and cover the top layer with a release cloth. S4. Hot pressing: Employing multi-stage temperature-pressure curves. (1) Stage 1: Low pressure, medium temperature. Increase the temperature from 0 to 100-110℃ at a rate greater than 10℃ / minute, stop heating, and maintain the constant temperature for 15-25 minutes. At the same time, increase the pressure to 15-20 MPa within 10 seconds to ensure uniform temperature transfer. The resin film will initially melt and begin to slowly wet the fiber bundles, expelling most of the air and avoiding the "airlock" phenomenon. (2) Stage 2: High pressure and high temperature. When the resin is completely melted and has the best fluidity, the temperature is raised to 145-155℃ within 10 minutes, and the pressure is uniformly increased to 25-40MPa and maintained for 35-60 minutes. At the same time, when the temperature reaches 130℃, ultrasonic-assisted hot pressing is used. The ultrasonic frequency is 20-28kHz, the power range is 1300-1500W, the amplitude is 15-25μm, and the pulse mode is used. The pulse period can be set to 1s on / 0.5s off. While performing traditional hot pressing, the ultrasonic vibration energy is introduced into the laminated material through the mold. The high-frequency vibration generates a microscopic "acoustic flow effect" and local thermal effect, so that the resin can completely penetrate between each fiber to achieve extreme densification. (3) Stage 3: Gradual cooling and pressure holding. Cool the temperature to 125-130℃ within 2-4 minutes, maintain the pressure at 25-35MPa, keep the temperature constant for 5-7 minutes, then cool the temperature to 80-90℃ within 5-10 minutes, maintain the pressure at 25-35MPa, then cool the temperature to 40-60℃ within 5-10 minutes, maintain the pressure at 25-35MPa, and release the pressure and demold after it has completely cooled to room temperature.

[0019] S5. Post-processing: Using a waterjet cutter, the square plates are cut into ergonomic curved bulletproof plate shapes. As needed, a layer of polyurethane (PU) coating is sprayed or rolled onto the surface of the bulletproof plate to enhance its environmental adaptability.

[0020] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a PE bulletproof plate, characterized in that, Includes the following steps: S1. Material preparation: Select UHMWPE fiber nonwoven fabric, thermoplastic resin film and encapsulation material, and modify them. S2, Layered Layup: Adopting a cross-layup structure (1) Before lay-up, the UHMWPE fiber nonwoven fabric is pre-stretched or preheated to flatten the fiber bundles in advance, reduce internal voids, and make it easier for the resin to impregnate later. (2) Clean the mold and lay down a layer of release cloth; (3) Lay the first layer of UHMWPE fiber nonwoven fabric with the fiber direction set at 0°, then lay a layer of resin film, and then lay the second layer of UHMWPE fiber nonwoven fabric with the fiber direction rotated 90° and perpendicular to the first layer. Repeat the above steps until all layers of nonwoven fabric and resin film are laid, and cover the top layer with a release cloth. S3. Hot pressing: Employing multi-stage temperature-pressure curves. (1) Stage 1: Low pressure, medium temperature, raise the temperature from 0 to 90-110℃ at a rate of more than 10℃ / minute, stop heating, keep the temperature constant for 15-25 minutes, and at the same time increase the pressure to 15-20 MPa within 10 seconds to make the temperature evenly transferred, the resin film initially melts and begins to slowly wet the fiber bundle, and most of the air is discharged. (2) Stage 2: High pressure and high temperature. When the resin is completely melted and has the best fluidity, the temperature is raised to 140-160℃ within 10 minutes, and the pressure is uniformly increased to 25-40MPa. This is maintained for 35-60 minutes to allow the resin to completely penetrate between each fiber and achieve ultimate densification. (3) Stage 3: Gradual cooling and pressure holding. Cool the temperature to 120-140℃ within 2-4 minutes, maintain the pressure at 25-35MPa, hold the temperature for 5-7 minutes, then cool the temperature to 70-100℃ within 5-10 minutes, maintain the pressure at 25-35MPa, then cool the temperature to 40-60℃ within 5-10 minutes, maintain the pressure at 25-35MPa, and release the pressure and demold after it has completely cooled to room temperature. S4. Post-processing: Using a waterjet cutter, the square plates are cut into ergonomic curved bulletproof plate shapes. As needed, a layer of polyurethane (PU) coating is sprayed or rolled onto the surface of the bulletproof plate to enhance its environmental adaptability.

2. The method for preparing a PE bulletproof plate according to claim 1, characterized in that: The pressure setting is as follows: Material modification in step S1 includes: (1) Fiber: UHMWPE fibers were subjected to plasma treatment; (2) Resin: Carbon nanotubes and graphene are added to the resin, and various thermoplastics are blended together.

3. The method for preparing a PE bulletproof plate according to claim 1, characterized in that: Ultrasonic-assisted hot pressing is used in step S3, the second stage of hot pressing.

4. The method for preparing a PE bulletproof plate according to claim 3, characterized in that: The ultrasonic frequency is 20–28 kHz, the power range is 1000–1500 W, the amplitude is 15–25 μm, and the pulse mode is used. The pulse period can be set to 1 s on / 0.5 s off.

5. The method for preparing a PE bulletproof plate according to claim 1, characterized in that: Some of the UHMWPE layers are pre-formed into tiny 3D structures and then composited with other flat layers.