Hybrid gradient fiber composite bulletproof laminated plate and preparation method thereof

Abstract

The invention discloses a hybrid gradient fiber composite bulletproof laminated plate and a preparation method thereof, and belongs to the technical field of composite target plates. The preparation method comprises the following steps: coating the surface of each aramid fiber cloth laminated layer with waterborne polyurethane, and sequentially performing drying and tailoring forming to obtain a plurality of tailored and formed aramid fiber cloth composite layers; respectively cutting and forming the plurality of ultra-high molecular weight polyethylene fiber non-woven fabric laminated layers; and sequentially carrying out staggered stacking, wrapping, mold embedding and hot press molding on the waterborne polyurethane layers in the multiple tailored and molded ultra-high molecular weight polyethylene fiber non-woven fabric laminated layers and the multiple tailored and molded aramid fiber cloth composite layers, so as to obtain the hybrid gradient fiber composite bulletproof laminated plate. The interface bonding between the aramid fiber cloth and the ultra-high molecular weight polyethylene non-woven cloth in the hybrid gradient fiber composite bulletproof laminated plate is firm, and the hybrid gradient fiber composite bulletproof laminated plate has good energy absorption and blunt impact resistance effects and good bulletproof performance.

Description

Technical Field

[0001] The invention belongs to the technical field of composite material target plates, and in particular relates to a mixed gradient fiber composite material bulletproof laminate and a preparation method thereof. Background Art

[0002] When a projectile penetrates a composite target plate, the projectile's kinetic energy is absorbed by the target through several different destruction and energy absorption mechanisms. Composite target plates dissipate the projectile's kinetic energy primarily through the following energy absorption mechanisms: compression and shear failure on the projectile-facing surface, fiber tensile fracture and large deformation bulging on the back surface, interlayer delamination, matrix crushing, and frictional energy dissipation between the projectile and the target plate. For the bullet-resistant fibers in composite materials, the stress conditions they experience during a bullet strike are extremely complex. In addition to axial tension, they are also subject to multiple stress modes such as lateral compression and axial shear. Therefore, while pursuing high tensile strength for bullet-resistant fibers, it is necessary to also consider improving their compression and shear resistance to maximize the actual bullet-resistant capabilities of high-performance fibers.

[0003] In terms of fiber protective materials, high-performance bulletproof fibers have varying properties. Furthermore, the anti-bullet energy absorption mechanism of fiber composites indicates that when a projectile penetrates a composite target plate, the damage occurs differently at different locations within the target plate, exhibiting a significant thickness effect. Therefore, one of the future development trends in fiber composites for bulletproof materials is to mix and match different fibers, leveraging their strengths and minimizing their weaknesses to fully utilize their unique performance advantages. However, in the actual preparation and processing process, different fibers use different resin systems, resulting in stratification at the fiber interfaces, low interfacial bonding strength, and poor ballistic performance. Summary of the Invention

[0004] One of the purposes of the present invention is to provide a method for preparing a hybrid gradient fiber composite bullet-proof laminate. The hybrid gradient fiber composite bullet-proof laminate prepared by this method has a strong interface bonding between the aramid fiber cloth and the ultra-high molecular weight polyethylene non-woven cloth, reduces the degree of interface stratification of different fibers, has a good energy absorption and blunt impact resistance effect, and has good ballistic performance.

[0005] A second object of the present invention is to provide a hybrid gradient fiber composite bulletproof laminate.

[0006] In order to achieve one of the above purposes, the present invention adopts the following technical solutions:

[0007] A method for preparing a hybrid gradient fiber composite bulletproof laminate, the method comprising the following steps:

[0008] Step S1, coating the surface of each aramid fiber cloth laminate with water-based polyurethane having a solid content of 25-35% and a pH value of 7-8 according to a glue ratio of 10-20:1, and then drying and cutting and forming the layers to obtain a plurality of cut and formed aramid fiber cloth composite layers;

[0009] Step S2, cutting and shaping a plurality of ultra-high molecular weight polyethylene fiber non-woven fabric laminates;

[0010] Step S3: stacking, wrapping, embedding in a mold, and hot-pressing the multiple cut and formed ultra-high molecular weight polyethylene fiber non-woven fabric layers and the waterborne polyurethane layer in the aramid fiber cloth composite layer in sequence to obtain a mixed gradient fiber composite bulletproof laminate.

[0011] Furthermore, in the step S1, the waterborne polyurethane is a fatty cluster polyester polyurethane.

[0012] Furthermore, the fatty cluster polyester polyurethane is one of polyethylene adipate polyurethane, polybutylene adipate polyurethane, polycaprolactone polyurethane and polycarbonate polyurethane.

[0013] Furthermore, the tensile strength of the fat cluster polyester polyurethane is 25-35 MPa, the elongation at break is 245-255%, and the stress at 100% strain is 10-20 MPa.

[0014] Furthermore, in step S3, the hot pressing process includes:

[0015] Clamp the mold for 3 to 5 seconds to adjust the displacement between the ultra-high molecular weight polyethylene fiber flat cloth laminate and the aramid fiber cloth composite layer;

[0016] Then, under a pressure of 3-5 MPa, heat it to 65-75°C, pressurize it to 7-13 MPa, continue heating it to 80-90°C, open the mold and release the air 2-3 times, then close the mold.

[0017] Then, at a temperature of 80-90°C, continue to pressurize to 20-30 MPa, then continue to heat to 128-130°C, keep warm and pressurize for 20-40 minutes, cool to below 50°C and then open the mold.

[0018] In order to achieve the second of the above objectives, the present invention adopts the following technical solutions:

[0019] A hybrid gradient fiber composite material bullet-proof laminate is prepared by the above-mentioned preparation method.

[0020] Furthermore, the hybrid gradient fiber composite bulletproof laminate comprises staggered aramid fiber cloth layers and ultra-high molecular weight polyethylene fiber non-woven cloth layers;

[0021] Waterborne polyurethane is coated between adjacent aramid fiber cloth layers and ultra-high molecular weight polyethylene fiber non-woven cloth layers.

[0022] Furthermore, the thickness of each layer of the aramid fiber cloth laminate is 0.2 to 0.5 mm;

[0023] The thickness of each layer of ultra-high molecular weight polyethylene fiber non-woven fabric laminate is 0.1 to 0.3 mm;

[0024] The thickness of the waterborne polyurethane is 0.05 to 0.1 mm.

[0025] Furthermore, the number of layers of the aramid fiber cloth laminate and the ultra-high molecular weight polyethylene fiber non-woven cloth laminate are both 3 to 8 layers.

[0026] Furthermore, the fiber content of the aramid fiber cloth laminate is 70-80%.

[0027] In summary, the solution proposed in the present invention has the following technical effects:

[0028] The present invention forms a three-dimensional cross-linked network structure after hot pressing of the water-based polyurethane layer, which increases the interface bonding strength between the aramid fiber and the ultra-high molecular weight polyethylene fiber by more than 20%, realizes firm interface bonding between the aramid fiber cloth and the ultra-high molecular weight polyethylene non-woven cloth, avoids interface stratification of different fibers, has good energy absorption and blunt impact resistance, and has good ballistic performance. After actual ballistic impact tests, no stratification phenomenon occurs, and is suitable for application in the fields of bulletproof helmets, bulletproof inserts, protective shields, etc. The hybrid gradient fiber composite bulletproof laminate of the present invention has a surface density of ≤5kg / m 2 Under the condition of no more than 100%, the test was carried out in accordance with the GJB4300A standard, and it can effectively defend against the shooting of the Type 51 7.62mm pistol bullet. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 Schematic diagram of a laminate of ultra-high molecular weight polyethylene fiber non-woven fabric;

[0031] Figure 2It is a side view of the ultra-high molecular weight polyethylene fiber non-woven fabric after lamination;

[0032] Figure 3 is a schematic diagram of the aramid fiber cloth laminate;

[0033] Figure 4 It is a side view of the aramid fiber cloth after lamination;

[0034] Figure 5 Schematic diagram of the laminated combination of aramid fiber cloth and ultra-high molecular weight polyethylene fiber non-woven cloth. DETAILED DESCRIPTION

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0036] This embodiment provides a method for preparing a hybrid gradient fiber composite bulletproof laminate, which comprises the following steps:

[0037] Step S1: coating the surface of each aramid fiber cloth laminate with a water-based polyurethane having a solid content of 25-35% and a pH value of 7-8 according to a glue ratio of 10-20:1, and then drying and cutting and forming the layers in sequence to obtain a plurality of cut-and-formed aramid fiber cloth composite layers.

[0038] The waterborne polyurethane in this embodiment has a solid content of 25-35% and a pH of 7-8. The waterborne polyurethane is a fatty cluster polyester polyurethane, selected from the group consisting of polyethylene adipate polyurethane, polybutylene adipate polyurethane, polycaprolactone polyurethane, and polycarbonate polyurethane. The fatty cluster polyester polyurethane has a tensile strength of 25-35 MPa, an elongation at break of 245-255%, and a stress at 100% strain of 10-20 MPa.

[0039] Step S2: cutting and shaping the plurality of ultra-high molecular weight polyethylene fiber non-woven fabric laminates.

[0040] Step S3: stacking, wrapping, embedding in a mold, and hot-pressing the multiple cut and formed ultra-high molecular weight polyethylene fiber non-woven fabric layers and the waterborne polyurethane layer in the aramid fiber cloth composite layer in sequence to obtain a mixed gradient fiber composite bulletproof laminate.

[0041] There are two ways of staggered stacking in this embodiment:

[0042] One is from top to bottom, the order of staggered stacking can be first the aramid fiber cloth laminate, and then the ultra-high molecular weight polyethylene fiber non-woven cloth laminate (that is, the top layer of the mixed gradient fiber composite bullet-proof laminate is the aramid fiber cloth laminate, and the bottom layer is the ultra-high molecular weight polyethylene fiber non-woven cloth laminate).

[0043] Another staggered stacking order is from top to bottom: first, the ultra-high molecular weight polyethylene fiber non-woven cloth is laminated, and then the aramid fiber cloth is laminated (that is, the top layer of the mixed gradient fiber composite bullet-proof laminate is the ultra-high molecular weight polyethylene fiber non-woven cloth laminate, and the bottom layer is the aramid fiber cloth laminate).

[0044] The hot pressing process in this embodiment includes:

[0045] Clamp the mold for 3 to 5 seconds to adjust the displacement between the ultra-high molecular weight polyethylene fiber flat cloth laminate and the aramid fiber cloth composite layer;

[0046] Then, under a pressure of 3-5 MPa, heat it to 65-75°C, pressurize it to 7-13 MPa, continue heating it to 80-90°C, open the mold and release the air 2-3 times, then close the mold.

[0047] Then, at a temperature of 80-90°C, continue to pressurize to 20-30 MPa, then continue to heat to 128-130°C, keep warm and pressurize for 20-40 minutes, cool to below 50°C and then open the mold.

[0048] Another embodiment provides a hybrid gradient fiber composite bullet-proof laminate. The hybrid gradient fiber composite bullet-proof laminate is prepared by the preparation method provided in the embodiment.

[0049] The structure of the hybrid gradient fiber composite bulletproof laminate in this embodiment is referenced Figure 5 , including staggered aramid fiber cloth laminates (reference Figure 3 and Figure 4 ) and ultra-high molecular weight polyethylene fiber non-woven fabric laminate (reference Figure 1 and Figure 2 A layer of waterborne polyurethane ( Figure 5(Not shown). Each layer of the aramid fiber cloth laminate has a thickness of 0.2 to 0.5 mm, each layer of the ultra-high molecular weight polyethylene fiber non-woven cloth laminate has a thickness of 0.1 to 0.3 mm, and each layer of the water-based polyurethane layer has a thickness of 0.05 to 0.1 mm. The water-based polyurethane in this embodiment is a fatty cluster polyester polyurethane, having a tensile strength of 25 to 35 MPa, an elongation at break of 245 to 255%, and a stress at 100% strain of 10 to 20 MPa. The water-based polyurethane is preferably selected from the group consisting of polyethylene adipate polyurethane, polybutylene adipate polyurethane, polycaprolactone polyurethane, and polycarbonate polyurethane.

[0050] In this embodiment, the number of layers of the aramid fiber cloth laminate and the aramid fiber cloth laminate are both 3 to 8. The fiber content of the aramid fiber cloth laminate is 70 to 80%.

[0051] The technical solution of this embodiment is described below using specific embodiments.

[0052] Example 1:

[0053] Step S1: Coat the upper and lower surfaces of each 0.3mm thick aramid fiber cloth laminate with a 0.08mm thick layer of polyethylene adipate polyurethane (PEA) with a solids content of 30% and a pH of 7.5 at a 15:1 adhesive ratio. The laminates are then dried and cut to form three aramid fiber cloth composite layers. The PEA polyurethane has a tensile strength of 30 MPa, an elongation at break of 250%, and a stress at 100% strain of 15 MPa. The fiber content of the aramid fiber cloth laminate is 75%.

[0054] Step S2: Cut and shape three ultra-high molecular weight polyethylene fiber non-woven fabric laminates with a thickness of 0.2 mm.

[0055] Step S3: stacking, wrapping, embedding in a mold, and hot-pressing the three cut and formed ultra-high molecular weight polyethylene fiber non-woven fabric layers and the polyethylene adipate polyurethane layers in the three aramid fiber cloth composite layers in sequence to obtain a mixed gradient fiber composite bulletproof laminate.

[0056] Among them, the process of hot pressing molding includes:

[0057] Close the mold for 4 seconds and observe whether the material has any overall displacement or excessive displacement between layers during the mold closing process. Make timely adjustments and calibration (i.e., adjust the displacement between the ultra-high molecular weight polyethylene fiber flat cloth laminate and the aramid fiber cloth composite layer).

[0058] Then, under a pressure of 4 MPa, the temperature was raised to 70°C, the pressure was increased to 10 MPa, the temperature was further raised to 85°C, the mold was opened and the air was released three times, and the mold was closed;

[0059] Then, at a temperature of 85°C, continue to pressurize to 25 MPa, then continue to heat to 129°C, keep warm and pressurize for 30 minutes, keep the pressure constant, pass coolant into the mold and cool to 45°C before opening the mold and taking out the mixed gradient fiber composite bulletproof laminate.

[0060] Among them, in the mixed gradient fiber composite bullet-proof laminate, from top to bottom, they are ultra-high molecular weight polyethylene fiber non-weft cloth laminate, polyethylene adipate type polyurethane layer, aramid fiber cloth laminate, ultra-high molecular weight polyethylene fiber non-weft cloth laminate, polyethylene adipate type polyurethane layer, aramid fiber cloth laminate, ultra-high molecular weight polyethylene fiber non-weft cloth laminate, polyethylene adipate type polyurethane layer and aramid fiber cloth laminate.

[0061] The interfacial peel strength between the aramid fibers and the ultra-high molecular weight polyethylene fibers in the hybrid gradient fiber composite bullet-proof laminate of this embodiment is 25N / 2.5cm, which is 25% higher than that of the PE film bonding structure, avoiding the interfacial stratification of different fibers, having a good energy absorption and blunt impact resistance effect, and having good ballistic performance.

[0062] The hybrid gradient fiber composite bulletproof laminate of this embodiment has a surface density of 4.8 kg / m 2 Under the condition of no more than 100%, the test was carried out in accordance with the GJB4300A standard, and it can effectively defend against the shooting of the Type 51 7.62mm pistol bullet.

[0063] Example 2:

[0064] Step S1: Coat the upper and lower surfaces of each 0.5mm thick aramid fiber cloth laminate with a 0.1mm thick layer of polybutylene adipate-based polyurethane (PAPU) with a solids content of 35% and a pH of 8 at a 20:1 adhesive ratio. The laminates are then dried and cut to form five aramid fiber cloth composite layers. The PAPU has a tensile strength of 35 MPa, an elongation at break of 255%, and a stress at 100% strain of 20 MPa. The fiber content of the aramid fiber cloth laminate is 80%.

[0065] Step S2: Cut and shape five ultra-high molecular weight polyethylene fiber non-woven fabric laminates with a thickness of 0.3 mm.

[0066] Step S3: Alternately stack, wrap, embed into a mold, and hot-press the five cut and formed ultra-high molecular weight polyethylene fiber free-weft cloth layers and the polybutylene adipate type polyurethane layers in the five aramid fiber cloth composite layers to obtain a mixed gradient fiber composite bulletproof laminate.

[0067] Among them, the process of hot pressing molding includes:

[0068] Close the mold for 5 seconds and observe whether the material has any overall displacement or excessive displacement between layers during the mold closing process. Make timely adjustments and calibration (i.e., adjust the displacement between the ultra-high molecular weight polyethylene fiber flat cloth laminate and the aramid fiber cloth composite layer).

[0069] Then, under a pressure of 5 MPa, the temperature was raised to 75°C, the pressure was increased to 13 MPa, the temperature was further raised to 90°C, the mold was opened and the air was released twice, and the mold was closed;

[0070] Then, at a temperature of 90°C, continue to pressurize to 30 MPa, then continue to heat to 130°C, keep warm and hold pressure for 40 minutes, keep the pressure constant, pass coolant into the mold and cool to 48°C before opening the mold and taking out the mixed gradient fiber composite bulletproof laminate.

[0071] Among them, in the mixed gradient fiber composite bullet-proof laminate, from top to bottom, they are aramid fiber cloth laminate, polybutylene adipate type polyurethane layer, ultra-high molecular weight polyethylene fiber non-weft cloth laminate, aramid fiber cloth laminate, polybutylene adipate type polyurethane layer, ultra-high molecular weight polyethylene fiber non-weft cloth laminate, aramid fiber cloth laminate, polybutylene adipate type polyurethane layer, ultra-high molecular weight polyethylene fiber non-weft cloth laminate, aramid fiber cloth laminate, polybutylene adipate type polyurethane layer, ultra-high molecular weight polyethylene fiber non-weft cloth laminate, aramid fiber cloth laminate, polybutylene adipate type polyurethane layer and ultra-high molecular weight polyethylene fiber non-weft cloth laminate.

[0072] The interfacial peel strength between the aramid fibers and the ultra-high molecular weight polyethylene fibers in the hybrid gradient fiber composite bullet-proof laminate of this embodiment is 23N / 2.5cm, which is 23% higher than that of the PE film bonding structure, avoiding the interfacial delamination of different fibers, having a good energy absorption and blunt impact resistance effect, and having good ballistic performance.

[0073] The hybrid gradient fiber composite bulletproof laminate of this embodiment has a surface density of 5kg / m 2 Under the condition of no more than 100%, the test was carried out in accordance with the GJB4300A standard, and it can effectively defend against the shooting of the Type 51 7.62mm pistol bullet.

[0074] Example 3:

[0075] Step S1: Coat the upper and lower surfaces of each 0.2mm thick aramid fiber cloth laminate with a 0.05mm thick layer of polycarbonate polyurethane (PCPU) with a solids content of 25% and a pH of 7 at a 10:1 adhesive ratio. The laminates are then dried and cut to form eight aramid fiber cloth composite layers. The PCPU has a tensile strength of 25 MPa, an elongation at break of 245%, and a stress at 100% strain of 10 MPa. The fiber content of the aramid fiber cloth laminate is 70%.

[0076] Step S2: Cut and shape 8 ultra-high molecular weight polyethylene fiber non-woven fabric laminates with a thickness of 0.1 mm.

[0077] Step S3: stacking, wrapping, embedding in a mold, and hot-pressing the eight cut and formed ultra-high molecular weight polyethylene fiber free-weft cloth layers and the polycarbonate polyurethane layers in the eight aramid fiber cloth composite layers in sequence to obtain a mixed gradient fiber composite bulletproof laminate.

[0078] Among them, the process of hot pressing molding includes:

[0079] Close the mold for 3 seconds and observe whether the material has any overall displacement or excessive displacement between layers during the mold closing process. Make timely adjustments and perform calibration (i.e., adjust the displacement between the ultra-high molecular weight polyethylene fiber flat cloth laminate and the aramid fiber cloth composite layer).

[0080] Then, under a pressure of 3MPa, the temperature is raised to 65°C, the pressure is increased to 7MPa, the temperature is further raised to 80°C, the mold is opened and the air is released twice, and the mold is closed;

[0081] Then, at a temperature of 80°C, continue to pressurize to 20 MPa, then continue to heat to 128°C, keep warm and hold pressure for 20 minutes, keep the pressure constant, pass coolant into the mold and cool to 48°C before opening the mold and taking out the mixed gradient fiber composite bulletproof laminate.

[0082] Among them, in the mixed gradient fiber composite bullet-proof laminate, from top to bottom, they are aramid fiber cloth laminate, polycarbonate polyurethane layer, ultra-high molecular weight polyethylene fiber non-woven cloth laminate, aramid fiber cloth laminate, polycarbonate polyurethane layer, ultra-high molecular weight polyethylene fiber non-woven cloth laminate, aramid fiber cloth laminate, polycarbonate polyurethane layer, ultra-high molecular weight polyethylene fiber non-woven cloth laminate, aramid fiber cloth laminate, polycarbonate polyurethane layer, ultra-high molecular weight polyethylene fiber non-woven cloth laminate, aramid fiber cloth laminate, polycarbonate polyurethane layer, ultra-high molecular weight polyethylene fiber non-woven cloth laminate, aramid fiber cloth laminate, polycarbonate polyurethane layer, ultra-high molecular weight polyethylene fiber non-woven cloth laminate, aramid fiber cloth laminate, polycarbonate polyurethane layer, ultra-high molecular weight polyethylene fiber non-woven cloth laminate, aramid fiber cloth laminate, polycarbonate polyurethane layer and ultra-high molecular weight polyethylene fiber non-woven cloth laminate.

[0083] The interfacial bonding strength and peel strength of the aramid fibers and ultra-high molecular weight polyethylene fibers in the hybrid gradient fiber composite bullet-proof laminate of this embodiment is 23N / 2.5cm, which is 23% higher than that of the PE film bonding structure, avoiding the interface stratification of different fibers, having a good energy absorption and blunt impact resistance effect, and good ballistic performance.

[0084] The hybrid gradient fiber composite bulletproof laminate of this embodiment has a surface density of 5kg / m 2 Under the condition of no more than 100%, the test was carried out in accordance with the GJB4300A standard, and it can effectively defend against the shooting of the Type 51 7.62mm pistol bullet.

[0085] The above embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A method for preparing a hybrid gradient fiber composite bulletproof laminate, characterized in that: The preparation method comprises the following steps: Step S1, coating the surface of each aramid fiber cloth laminate with water-based polyurethane having a solid content of 25-35% and a pH value of 7-8 according to a glue ratio of 10-20:1, and then drying and cutting and forming the layers to obtain a plurality of cut and formed aramid fiber cloth composite layers; Step S2, cutting and shaping a plurality of ultra-high molecular weight polyethylene fiber non-woven fabric laminates; Step S3: stacking, wrapping, embedding in a mold, and hot-pressing the multiple cut and formed ultra-high molecular weight polyethylene fiber non-woven fabric layers and the waterborne polyurethane layer in the aramid fiber cloth composite layer in sequence to obtain a mixed gradient fiber composite bulletproof laminate.

2. The preparation method according to claim 1, characterized in that In the step S1, the waterborne polyurethane is a fatty cluster polyester polyurethane.

3. The preparation method according to claim 2, characterized in that The fatty cluster polyester polyurethane is one of polyethylene adipate polyurethane, polybutylene adipate polyurethane, polycaprolactone polyurethane and polycarbonate polyurethane.

4. The preparation method according to claim 3, characterized in that The tensile strength of the fat cluster polyester polyurethane is 25-35 MPa, the elongation at break is 245-255%, and the stress at 100% strain is 10-20 MPa.

5. The preparation method according to any one of claims 1 to 4, characterized in that In step S3, the hot pressing process includes: Clamp the mold for 3 to 5 seconds to adjust the displacement between the ultra-high molecular weight polyethylene fiber flat cloth laminate and the aramid fiber cloth composite layer; Then, under a pressure of 3-5 MPa, heat it to 65-75°C, pressurize it to 7-13 MPa, continue heating it to 80-90°C, open the mold and release the air 2-3 times, then close the mold. Then, at a temperature of 80-90°C, continue to pressurize to 20-30 MPa, then continue to heat to 128-130°C, keep warm and pressurize for 20-40 minutes, cool to below 50°C and then open the mold.

6. A hybrid gradient fiber composite bulletproof laminate, characterized in that: The mixed gradient fiber composite bulletproof laminate is prepared by the preparation method according to any one of claims 1 to 5.

7. The hybrid gradient fiber composite bulletproof laminate according to claim 6, characterized in that: The hybrid gradient fiber composite bulletproof laminate comprises staggered aramid fiber cloth layers and ultra-high molecular weight polyethylene fiber non-woven cloth layers; A layer of waterborne polyurethane is coated between adjacent aramid fiber cloth layers and ultra-high molecular weight polyethylene fiber non-woven cloth layers.

8. The hybrid gradient fiber composite bulletproof laminate according to claim 7, characterized in that: The thickness of each layer of aramid fiber cloth laminate is 0.2 to 0.5 mm; The thickness of each layer of ultra-high molecular weight polyethylene fiber non-woven fabric laminate is 0.1 to 0.3 mm; The thickness of the waterborne polyurethane is 0.05 to 0.1 mm.

9. The hybrid gradient fiber composite bulletproof laminate according to claim 8, characterized in that: The number of layers of the aramid fiber cloth laminate and the ultra-high molecular weight polyethylene fiber non-woven cloth laminate are both 3 to 8 layers.

10. The hybrid gradient fiber composite bulletproof laminate according to claim 9, characterized in that: The fiber content of the aramid fiber cloth laminate is 70-80%.

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