A lightweight composite armor and its preparation method

Abstract

The present invention belongs to the technical field of protective composite materials, and more specifically, relates to a lightweight composite armor and a preparation method thereof. The lightweight composite armor includes n layers of para-aramid fiber cloth and n - 1 layers of thermoplastic resin, the para-aramid fiber cloth and the thermoplastic resin are alternately stacked, and both the top layer and the bottom layer are para-aramid fiber cloth, n is an integer, and n ≥ 2. The lightweight composite armor of the present invention is obtained by alternately stacking a thermoplastic polyolefin resin as a resin matrix and an aramid fiber cloth. The thermoplastic polyolefin resin has a high elongation at break. Experiments prove that compared with conventional resin matrices such as epoxy resin or polycarbonate, the composite of the thermoplastic polyolefin elastomer resin and the aramid fiber cloth adopted in the present invention exhibits more excellent protective performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of protective composite materials, and more specifically, relates to a lightweight composite armor and a preparation method thereof. Background Art

[0002] At present, the main material of bulletproof materials is para-aramid woven fabric. The woven fabric is woven by aramid filaments in the warp and weft directions, and is prepared into an aramid fiber reinforced resin matrix composite material with resin through molding. Aramid fiber has been widely used in many fields such as aerospace due to its excellent properties such as high specific modulus, high specific strength, low density, fatigue resistance, and high temperature resistance. However, aramid fiber has a high crystallinity, lacks active groups on the surface, has weak intermolecular hydrogen bond binding, poor wettability with resin, and low interfacial bonding performance of the composite material prepared with resin, very poor adhesion and wettability, and low interfacial bonding between the two phases.

[0003] At present, as one of the most commonly used resins, epoxy resin has disadvantages such as high brittleness and poor anti-cracking performance. As the resin matrix for fiber reinforcement, the main function of epoxy resin is to transfer stress between fibers; slow down the impact of external force on the composite material. However, as the matrix of the composite material, the protective performance of the protective armor prepared by it still needs to be further improved.

[0004] In recent years, it has been found that ultra-high molecular weight polyethylene fiber has more excellent bulletproof performance compared with aramid fiber. However, ultra-high molecular weight polyethylene fiber has poor temperature resistance and flame retardancy, and cannot meet the temperature resistance and flame retardancy requirements during actual application. Summary of the Invention

[0005] The purpose of the present invention is to provide a lightweight composite armor and a preparation method thereof to solve the technical problems such as poor protective performance of the existing composite armor.

[0006] To achieve the above purpose, the present invention provides a lightweight composite armor, which includes n layers of para-aramid fiber cloth and n - 1 layers of thermoplastic resin. The para-aramid fiber cloth and the thermoplastic resin are alternately stacked, and both the top layer and the bottom layer are para-aramid fiber cloth. n is an integer and n≥2.

[0007] Preferably, the thermoplastic resin includes an elastomer resin with an elongation at break greater than or equal to 300%, preferably an elastomer resin with an elongation at break greater than or equal to 400%.

[0008] Preferably, the elastomer resin is a polyolefin resin.

[0009] More preferably, the elastomer resin is a polyolefin resin with an elongation at break greater than or equal to 400%, in which the molar percentage content of polypropylene is greater than 70%.

[0010] Preferably, the polyolefin resin is in granular or non-woven form.

[0011] More preferably, the polyolefin resin is in non-woven form, and the non-woven polyolefin resin is prepared by a meltblowing process.

[0012] Preferably, the included angle between any two layers of para-aramid fiber cloth is 0°, 90° or 45°.

[0013] Preferably, the thermoplastic resin further contains a flame retardant, and the flame retardant is a mixture of ammonium polyphosphate, aluminum hydroxide and montmorillonite, wherein the mass ratio of ammonium polyphosphate, aluminum hydroxide and montmorillonite is (12-18):(3-7):(3-7).

[0014] Preferably, the areal density of the para-aramid fiber cloth is 300-400 g / cm 2 ; the para-aramid fiber cloth is plain weave, twill weave, satin weave, basket weave or bi-axial fabric, and the single yarn breaking strength of the para-aramid fiber cloth ≥ 22.5 cN / dtex, more preferably the single yarn breaking strength ≥ 23.5 cN / dtex; the mass percentage content of the thermoplastic resin in the composite armor is 15%-40%, and the mass percentage content of the flame retardant in the thermoplastic resin is 15%-30%; the areal density of the composite armor is 5-30 kg / m 2 .

[0015] According to another aspect of the present invention, a method for preparing the light composite armor is provided. After the para-aramid fiber cloth and the thermoplastic resin are alternately laminated, they are pressed at 100-200 °C and a pressure of 2-20 MPa for 10-70 min.

[0016] Generally speaking, compared with the prior art by the above technical solutions conceived by the present invention, the following beneficial effects are obtained:

[0017] (1) A light composite armor provided by the present invention is obtained by alternately laminating a thermoplastic polyolefin resin as a matrix with an aramid fiber cloth. The thermoplastic polyolefin resin has a high elongation at break. Experiments prove that compared with conventional resin matrices such as epoxy resin or polycarbonate, the composite of the thermoplastic polyolefin elastomer resin and the aramid fiber cloth adopted by the present invention exhibits more excellent energy absorption performance.

[0018] (2) For the light composite armor provided by the present invention, in the preferred embodiment, the thermoplastic resin is made into non-woven fabric, and the composite armor obtained by compounding has better protection performance than the granular resin material.

[0019] (3) The lightweight composite armor provided by the present invention, in a preferred embodiment, uses an elastomeric polyolefin resin with an elongation at break greater than 400% and a molar percentage content of polypropylene greater than or equal to 70% as the resin matrix of the composite armor of the present invention. Experiments have found that compared with other resin matrices, the protective performance of the composite armor of the present invention has been significantly improved.

[0020] (4) The present invention provides a lightweight composite armor. In a preferred embodiment, a flame retardant is introduced into the thermoplastic resin, and a flame retardant material is introduced into the resin matrix. While not affecting the overall energy absorption performance of the composite armor, it ensures that the composite armor has excellent high-temperature resistance and flame retardant properties.

[0021] (5) The lightweight composite armor of the present invention uses a thermoplastic elastomer resin that does not contain elements such as nitrogen and halogen, and does not have smoke toxicity during application, making it more environmentally friendly and safer. Description of the Drawings

[0022] Figure 1 is a schematic structural diagram of the lightweight composite armor of the present invention.

[0023] In all the drawings, the same reference numerals are used to represent the same elements or structures, where:

[0024] 1 - para - aramid fiber cloth; 2 - thermoplastic resin. Detailed Embodiments

[0025] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following further elaborates on the present invention in conjunction with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] A lightweight composite armor provided by the present invention includes n layers of para - aramid fiber cloth and n - 1 layers of thermoplastic resin. The para - aramid fiber cloth and the thermoplastic resin are alternately laminated, and both the top layer and the bottom layer are para - aramid fiber cloth. n is an integer and n ≥ 2. In this lightweight composite armor, the thermoplastic resin serves as the matrix, and the para - aramid fiber cloth serves as the reinforcing fiber material. The two are compounded by molding, effectively improving the anti - penetration performance of the composite material and enhancing the bullet - proof performance of the composite armor.

[0027] The para-aramid fiber cloth can be woven into plain weave, twill weave, satin weave, biaxial, square and other weaving structures as needed. In some embodiments, the thermoplastic resin comprises an elastomer resin with an elongation at break greater than or equal to 300%, preferably an elastomer resin with an elongation at break greater than or equal to 400%. In the experiments of the present invention, it is found that when an elastomer resin with a higher elongation at break is used as the resin matrix of the composite armor of the present invention, compared with traditional resin materials with a low elongation at break, such as epoxy resin or polycarbonate, the anti-penetration performance, that is, the bulletproof performance, of the composite armor can be significantly improved.

[0028] In some preferred embodiments, the elastomer resin is a polyolefin resin. It includes but is not limited to polyethylene, polypropylene, block copolymerized polypropylene, copolymers of polyethylene and polypropylene, etc. Among them, the preferred elastomer resin is a polyolefin resin with an elongation at break greater than or equal to 400%, and the molar percentage content of polypropylene is greater than or equal to 70%. In some embodiments, the preparation method of the copolymer of polyethylene and polypropylene includes the following steps: using ethylene and propylene as monomers, and under the catalytic action of a metallocene catalyst, preparing the copolymer by a solution polymerization method, wherein the molar percentage fraction of propylene monomer in the monomers is greater than or equal to 70%. In some other embodiments, the polyolefin is injection-molded copolymerized PP polypropylene, preferably Yangzi Petrochemical K8003 injection-molded copolymerized PP polypropylene, and its elongation at break is 500%.

[0029] The thermoplastic resin in the composite armor of the present invention can be in granular or non-woven fabric form. It is found in the experiments that when the granular thermoplastic resin and the aramid fiber cloth are alternately laminated, compared with the thermoplastic resin made into non-woven fabric form, the granular resin may affect the energy absorption performance of the composite armor material to a certain extent due to uneven distribution after being compounded with the aramid fiber cloth. In a preferred embodiment, the thermoplastic resin in non-woven fabric form is compounded with the aramid fiber cloth. The thermoplastic resin in non-woven fabric form of the present invention is prepared by a meltblowing process. The meltblowing process can use conventional meltblowing equipment. For example, for the polyolefin thermoplastic resin of the present invention, a customized short fiber intercalation meltblown non-woven system equipment can be used to meltblow to obtain non-woven fabric at 240 - 260°C and 2.5 - 3.5 MPa.

[0030] In order to improve the flame retardancy of the prepared composite light armor, in some embodiments, the thermoplastic resin of the present invention also contains a flame retardant, and the flame retardant includes but is not limited to one or more of ammonium polyphosphate, aluminum hydroxide, and montmorillonite, etc. In some embodiments, the mass ratio of ammonium polyphosphate, aluminum hydroxide, and montmorillonite in the flame retardant is (12 - 18):(3 - 7):(3 - 7).

[0031] In some embodiments, the areal density of the para-aramid fiber cloth is 300 - 400 g / cm 2; The para-aramid fiber cloth is plain weave, twill weave, satin weave, basket weave or biaxial fabric. The single yarn breaking strength of the para-aramid fiber cloth is ≥22.5 cN / dtex, and preferably ≥23.5 cN / dtex. The mass percentage content of the thermoplastic resin in the composite armor is 15%-40%, and the mass percentage content of the flame retardant in the thermoplastic resin is 15%-30%. The areal density of the composite armor is 5-30 kg / m 2 , and the composite armor within the above parameter range has good protection performance.

[0032] The present invention also provides a preparation method of the light composite armor. After the para-aramid fiber cloth and the thermoplastic resin are alternately laminated, they are pressed at 100-200 °C and a pressure of 2-20 MPa for 10-70 min to make it.

[0033] The following are examples:

[0034] Example 1

[0035] A bulletproof composite material is pressed from 27 layers of basket weave para-aramid fiber cloth and thermoplastic resin layers spaced between them (0° laying angle, the same in other examples). The top layer and the bottom layer are both basket weave aramid fiber cloth. One layer of basket weave para-aramid fiber cloth is defined as 1, and one layer of thermoplastic resin is defined as 2. Therefore, the arrangement order of the para-aramid fiber cloth and the thermoplastic resin from top to bottom of this bulletproof composite material is: 121212121...1.

[0036] The thermoplastic resin is a thermoplastic polyolefin resin, which is a copolymer of polyethylene and polypropylene. Its preparation method is as follows: Using ethylene and propylene as monomers, after nitrogen evacuation, it is switched to propylene gas and ethylene gas, and toluene and co-catalyst MAO (10% toluene solution, product of Witco Corporation) are added in sequence. After the dissolution equilibrium, under the catalytic action of metallocene catalyst rac-Me 2 Si(Ind) 2 ZrCl 2 , a granular thermoplastic resin is prepared by solution polymerization method. The polymerization product is terminated with acidified ethanol. The molar percentage of propylene in the monomers is 80%, and the molar percentage of ethylene is 20%. The preparation method of the thermoplastic polyolefin resin in this example refers to the literature (Zhu Yinbang et al., Study on the Isotactic Polymerization of Propylene Catalyzed by rac-Me 2 Si(Ind) 2 ZrCl 2 Supported Catalyst, Acta Polymerica Sinica, August 2000, Issue 4). The copolymer of polyethylene and polypropylene prepared in this example has an elongation at break of 650%.

[0037] Twenty-seven layers of para-aramid fiber cloth and the above-mentioned thermoplastic polyolefin resin particles therebetween are taken, and 15 g of ammonium polyphosphate, 5 g of aluminum hydroxide, and 5 g of montmorillonite are added to every 100 g of the thermoplastic polyolefin resin particles, and they are pressed at 150 °C and 10 MPa for 60 min to obtain the above-mentioned bulletproof composite material.

[0038] The areal density of the aramid cloth used in the above-mentioned bulletproof composite material is 340 g / cm 2 , the breaking strength of a single yarn is 23.5 cN / dtex, the content of the glue (the glue is a copolymer of polyethylene and polypropylene) in the composite material is 18%, and the areal density of the composite material is 10.5 Kg / m 2 . The target plate is named 1#.

[0039] Example 2

[0040] A bulletproof composite material is formed by laminating and pressing 27 layers of square plain para-aramid fiber cloth and thermoplastic resin layers spaced therebetween, with square plain aramid fiber cloth on both the top and bottom layers. One layer of square plain para-aramid fiber cloth is defined as 1, and one layer of thermoplastic resin is defined as 2. Therefore, the arrangement order of the para-aramid fiber cloth and the thermoplastic resin from top to bottom in this bulletproof composite material is: 121212121...1.

[0041] The thermoplastic resin is the thermoplastic polyolefin resin of Example 1, and the thermoplastic resin is in the form of non-woven fabric, that is, the polyolefin resin particles of Example 1 are made into non-woven fabric, and its preparation process is as follows: The granular polymer is fed into the feeding machine by the melt blowing process in a customized short fiber intercalated melt blowing non-woven system equipment and suctioned into the hopper of the screw extruder, and the feeding rate is 80 g / min. The die head temperature is set at 250 °C, the pressure is set at 3 MPa, and the polymer melt stream extruded from the die head spinneret holes is drawn by high-speed hot air to form ultrafine fibers and condense on the drum, and a non-woven fabric is made by its own adhesion. Air is blown with cold air, and the winding speed is 120 r / min. A thermoplastic resin non-woven fabric with a thickness of 1 mm and an areal density of 500 Kg / m 2 is prepared.

[0042] The above-mentioned bulletproof composite material is made by laminating 27 layers of para-aramid fiber cloth and the thermoplastic polyolefin resin non-woven fabric therebetween, and 15 g of ammonium polyphosphate, 5 g of aluminum hydroxide, and 5 g of montmorillonite are added to every 100 g of the thermoplastic polyolefin resin non-woven fabric, and they are pressed at 150 °C and 10 MPa for 60 min.

[0043] The areal density of the aramid cloth used in the above-mentioned bulletproof composite material is 340 g / cm 2 , the breaking strength of a single yarn is 23.5 cN / dtex, the glue content in the composite material is 18%, and the areal density is 10.5 kg / ㎡. The target plate is named 2#.

[0044] Example 3

[0045] A bulletproof composite material is made by laminating and pressing 27 layers of square plain para-aramid fiber cloth with thermoplastic resin layers interspersed between them. The top and bottom layers are both square plain aramid fiber cloth. One layer of square plain para-aramid fiber cloth is defined as 1, and one layer of thermoplastic resin is defined as 2. Therefore, the arrangement order of para-aramid fiber cloth and thermoplastic resin from top to bottom in this bulletproof composite material is: 121212121...1.

[0046] The thermoplastic resin is thermoplastic polypropylene resin particles (K8003, that is, injection-grade copolymerized PP polypropylene of Yangzi Petrochemical K8003). 27 layers of para-aramid fiber cloth and the thermoplastic polypropylene particles K8003 between them are used. At the same time, 15 grams of ammonium polyphosphate, 5 grams of aluminum hydroxide, and 5 grams of montmorillonite are added to every 100 grams of thermoplastic polypropylene particles, and they are pressed at 150 °C and 10 MPa for 60 minutes to obtain the above bulletproof composite material.

[0047] The areal density of the aramid cloth used in the above bulletproof composite material is 340 g / cm 2 , the breaking strength of a single yarn is 23.5 cN / dtex, the content of the glue (that is, thermoplastic polypropylene resin) in the pressed bulletproof composite material is 18%, and the areal density of the composite material is 10.5 Kg / ㎡. The target board is named 3#.

[0048] Example 4

[0049] A bulletproof composite material is made by laminating and pressing 27 layers of square plain para-aramid fiber cloth with thermoplastic resin layers interspersed between them. The top and bottom layers are both square plain aramid fiber cloth. One layer of square plain para-aramid fiber cloth is defined as 1, and one layer of thermoplastic resin is defined as 2. Therefore, the arrangement order of para-aramid fiber cloth and thermoplastic resin from top to bottom in this bulletproof composite material is: 121212121...1.

[0050] The thermoplastic resin is the thermoplastic polypropylene resin of Example 3. The thermoplastic resin is in the form of non-woven fabric, that is, the polypropylene resin particles of Example 3 are made into non-woven fabric. The preparation process is as follows: Using the meltblown process, the granular polymer is fed into the feeding machine in a customized short fiber intercalated meltblown non-woven system equipment and sucked into the hopper of the screw extruder, and the feeding rate is 80 g / min. The die head temperature is set at 250 °C, the pressure is set at 3 MPa, and the polymer melt stream extruded from the die head spinneret holes is drawn by high-speed hot air, thereby forming ultrafine fibers and condensing on the drum, and made into non-woven fabric by its own adhesion. Air is blown with cold air, and the winding speed is 120 r / min. A thermoplastic resin non-woven fabric with a thickness of 1 mm and an areal density of 500 Kg / m 2 is prepared.

[0051] The above bulletproof composite material is made by pressing 27 layers of para-aramid fiber cloth and non-woven thermoplastic polypropylene resin between them. At the same time, 15 grams of ammonium polyphosphate, 5 grams of aluminum hydroxide, and 5 grams of montmorillonite are added to every 100 grams of the thermoplastic polypropylene non-woven fabric, and it is pressed at 150 °C and 10 MPa for 60 minutes.

[0052] The areal density of the aramid cloth used in the above bulletproof composite material is 340 g / cm 2 , the breaking strength of a single yarn is 23.5 cN / dtex, the content of the glue (i.e., thermoplastic polypropylene resin) in the pressed bulletproof composite material is 18%, and the areal density of the composite material is 10.5 Kg / m 2 . The target board is named 4#.

[0053] Comparative Example 1

[0054] A bulletproof composite material is made by pressing 27 layers of twill para-aramid fiber cloth and thermoplastic resin laid alternately between them. Both the top layer and the bottom layer are twill aramid fiber cloth. One layer of twill para-aramid fiber cloth is defined as 1, and one layer of thermoplastic resin is defined as 2. Therefore, the arrangement order of the para-aramid fiber cloth and the thermoplastic resin from top to bottom in this bulletproof composite material is: 121212121...1.

[0055] The thermoplastic resin is thermoplastic polyethylene resin particles (Beijing Yanhua Petrochemical Co., Ltd., DHPE-5000s). 27 layers of para-aramid fiber cloth and the thermoplastic polyethylene particles between them are pressed at 150 °C and 10 MPa for 60 minutes, and the above bulletproof composite material is obtained. At the same time, 15 grams of ammonium polyphosphate, 5 grams of aluminum hydroxide, and 5 grams of montmorillonite are added to every 100 grams of the thermoplastic polyethylene particles.

[0056] The areal density of the aramid cloth used in the above bulletproof composite material is 340 g / cm 2 , the breaking strength of a single yarn is 23.5 cN / dtex, the content of the glue (i.e., thermoplastic polyethylene resin) in the pressed bulletproof composite material is 18%, and the areal density of the composite material is 10.74 Kg / m 2 . The target board is named 5#.

[0057] Comparative Example 2

[0058] Other conditions are the same as those in Example 1, except that the thermoplastic resin in Example 1 is replaced with the epoxy resin in this comparative example (Phoenix brand WSR6101 epoxy resin, Nantong Xingchen Synthetic Materials Co., Ltd.).

[0059] Specifically:

[0060] A bulletproof composite material is made by laminating and pressing 27 layers of plain-weave para-aramid fiber cloth with epoxy resin sandwiched in between. The top and bottom layers are both plain-weave aramid fiber cloth. One layer of plain-weave para-aramid fiber cloth is defined as 1, and one layer of epoxy resin is defined as 2. Therefore, the arrangement order of para-aramid fiber cloth and epoxy resin from top to bottom in this bulletproof composite material is: 121212121...1. As Figure 1 shown.

[0061] The above bulletproof composite material is made by pressing 27 layers of para-aramid fiber cloth and the epoxy resin in between at 150 °C and a pressure of 10 MPa for 60 minutes.

[0062] The aramid cloth used in the above bulletproof composite material has a surface density of 340 g / cm 2 , the breaking strength of a single yarn is 23.5 cN / dtex, the content of the glue (i.e., epoxy resin) in the pressed bulletproof composite material is 18%, and the surface density of the composite material is 10.5 g / m 2 . The target board is named 6#.

[0063] Comparative Example 3

[0064] Other conditions are the same as in Example 1, except that the thermoplastic resin in Example 1 is replaced with the polycarbonate of this comparative example. Specifically:

[0065] A bulletproof composite material is made by laminating and molding 27 layers of plain-weave para-aramid fiber cloth with polycarbonate sandwiched in between. The top and bottom layers are both plain-weave aramid fiber cloth. One layer of plain-weave para-aramid fiber cloth is defined as 1, and one layer of polycarbonate is defined as 2. Therefore, the arrangement order of para-aramid fiber cloth and polycarbonate from top to bottom in this bulletproof composite material is: 121212121...1.

[0066] The thermoplastic resin is polycarbonate PC, (longhua PC-835, Sichuan Longhua Optoelectronic Film Co., Ltd.), with a thickness of 0.125 mm and a surface density of 0.13 Kg / m 2 of thermoplastic resin.

[0067] The above bulletproof composite material is made by pressing 27 layers of para-aramid fiber cloth and the polycarbonate in between at 150 °C and a pressure of 10 MPa for 60 minutes.

[0068] The aramid cloth used in the above bulletproof composite material has a surface density of 340 g / cm 2 , the breaking strength of a single yarn is 23.5 cN / dtex, the content of the glue (i.e., polycarbonate) in the pressed bulletproof composite material is 18%, and the surface density of the composite material is 10.5 kg / m 2 . The target board is named 7#.

[0069] The anti-penetration performance of the composite armors of Examples 1 to 4 and Comparative Examples 1 to 3 was tested. According to GB / T32493-2016, the anti-penetration performance test was carried out at normal temperature and pressure. A spherical fragment projectile with a diameter of 10 mm was selected, the shooting distance was 5 m, the incident normal angle was 0°, the velocity measurement interval I was 1140 mm, the distance between the measurement point I and the target was 2000 mm, the velocity measurement interval II was 1100 mm, and the distance between the measurement point II and the target was 2700 mm. The equipment and instruments selected included a timer, a vernier caliper, a meter scale, and an electronic weighing scale, etc. The measured results are shown in Table 1.

[0070] Table 1 Data table of energy absorption of aramid target shooting

[0071] Number Velocity before hitting the target Velocity after hitting the target Absorbed kinetic energy Energy absorption per unit area density Remarks 1# 851.1 687.6 411.5 45.57 Penetration 2# 875.4 724.2 501.6 47.63 Penetration 3# 882.2 752.8 439.2 41.7 Penetration 4# 902.1 771.6 453.4 43.05 Penetration 5# 798.4 661.4 391.1 38.6 Penetration 6# 894.4 775.7 411.5 38.75 Penetration 7# 968.9 867.6 386.4 38.4 Penetration

[0072] Example 1 used copolymer thermoplastic resin particles of polyethylene and polypropylene. Example 2 used non-woven fabric made of the thermoplastic resin particles of Example 1. Example 3 used K8003 block copolymerized polypropylene thermoplastic resin particles. Example 4 used K8003 block copolymerized polypropylene thermoplastic resin non-woven fabric. Comparative Example 1 used polyethylene thermoplastic resin particles. Comparative Examples 2 and 3 used epoxy resin and polycarbonate respectively. The above resin materials from Ezhong were used as the resin matrix for preparing lightweight composite armor composite materials in each example or comparative example, and the fiber reinforcement materials and the number of layers in the composite materials were the same. It can be seen from Table 1 that Examples 2 and 4 using non-woven thermoplastic resin as the resin matrix achieved slightly higher energy absorption per unit surface density than the granular polyolefin thermoplastic resins of Examples 1 and 3. This may be because the uneven distribution of the granular resin affected its energy absorption effect to a certain extent. In addition, the polypropylene content of the polyolefin resins used in Examples 1, 2, 3, and 4 was all higher than 70%. Compared with the polyethylene of Comparative Example 1, the epoxy resin of Comparative Example 2, and the polycarbonate of Comparative Example 3 as the resin matrix of the composite protective material, the protective performance was improved by more than 20%. The possible reason is that the polyolefin resin itself has a relatively high elongation at break. The elongation at break of the polyolefin elastomer resin with a high polypropylene content reaches more than 500%. The elongation at break of the thermoplastic resins in Examples 1 and 2 was 650%, and that in Examples 3 and 4 was 500%, which was much higher than the elongation at break of polyethylene, epoxy resin, and polycarbonate. When compounded with aramid fiber to press the composite protective material, the protective performance of the protective material can be significantly improved.

[0073] Example 5

[0074] A bulletproof composite material is made by laminating and pressing 54 layers of plain-weave para-aramid fiber cloth with thermoplastic resin layers interleaved between them. The top and bottom layers are both plain-weave para-aramid fiber cloth. One layer of plain-weave para-aramid fiber cloth is defined as 1, and one layer of thermoplastic resin is defined as 2. Therefore, the arrangement order of para-aramid fiber cloth and thermoplastic resin from top to bottom in this bulletproof composite material is: 121212121...1.

[0075] The thermoplastic resin is the thermoplastic polyolefin resin of Example 2. The thermoplastic resin is a non-woven fabric material, that is, the polyolefin resin particles of Example 1 are made into non-woven fabric. Its preparation process is as follows: Using the meltblowing process, the granular polymer is fed into the feeding machine in a customized short fiber intercalated meltblown non-woven system equipment and suctioned into the hopper of the screw extruder, and the feeding rate is 80 g / min. The die head temperature is set at 250 °C, the pressure is set at 3 MPa, and the polymer melt stream extruded from the die head spinneret holes is stretched by high-speed hot air, thereby forming ultrafine fibers and condensing on the drum, and a non-woven fabric is made by its own adhesion. Air is blown with cold air, and the winding speed is 120 r / min. A thermoplastic resin non-woven fabric with a thickness of 1 mm and a surface density of 500 Kg / m 2 is prepared.

[0076] The above bulletproof composite material is made by pressing 54 layers of para-aramid fiber cloth and the thermoplastic polyolefin resin non-woven fabric between them, and at the same time adding 15 grams of ammonium polyphosphate, 5 grams of aluminum hydroxide, and 5 grams of montmorillonite to every 100 grams of thermoplastic polyolefin non-woven fabric, and pressing at 150 °C and 10 MPa for 60 minutes.

[0077] The surface density of the aramid cloth used in the above bulletproof composite material is 340 g / cm 2 , the breaking strength of a single yarn is 23.5 cN / dtex, the content of the glue (i.e., thermoplastic polyolefin resin) in the pressed bulletproof composite material is 18%, and the surface density of the composite material is 21.98 Kg / m 2 .

[0078] It is easy for those skilled in the art to understand that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A lightweight composite armor, characterized in that, it is formed by pressing after alternately laminating para-aramid fiber cloth and thermoplastic resin. The para-aramid fiber cloth is n layers, the thermoplastic resin is n - 1 layers, and both the top layer and the bottom layer are para-aramid fiber cloth. n is an integer and n ≥ 2; the thermoplastic resin contains an elastomer resin with an elongation at break greater than or equal to 400%. The elastomer resin is a polyolefin resin, in which the molar percentage content of polypropylene is greater than 70%; the mass percentage content of the thermoplastic resin in this composite armor is 15% - 40%.

2. The composite armor according to claim 1, characterized in that, the polyolefin resin is in granular or non-woven fabric form.

3. The composite armor according to claim 1, characterized in that, the polyolefin resin is in non-woven fabric form, and the non-woven fabric polyolefin resin is prepared by a melt-blown process.

4. The lightweight composite armor according to claim 1, characterized in that, the included angle between any two layers of para-aramid fiber cloth is 0°, 90° or 45°.

5. The composite armor according to claim 1, characterized in that, the thermoplastic resin further contains a flame retardant, and the flame retardant is a mixture of ammonium polyphosphate, aluminum hydroxide and montmorillonite, where the mass ratio of ammonium polyphosphate, aluminum hydroxide and montmorillonite is (12 - 18):(3 - 7):(3 - 7).

6. The lightweight composite armor according to claim 5, characterized in that, The areal density of the para-aramid fiber cloth is 300-400 g / cm 2 ; the para-aramid fiber cloth is a plain weave, twill weave, satin weave, basket weave or biaxial fabric, and the breaking strength of the single yarn constituting the para-aramid fiber cloth is ≥22.5 cN / dtex; In the composite armor, the mass percentage content of the flame retardant in the thermoplastic resin is 15%-30%; the areal density of the composite armor is 5-30 kg / m 2 .

7. The lightweight composite armor according to claim 1, characterized in that, the pressing is specifically: after alternately laminating the para-aramid fiber cloth and the thermoplastic resin, it is pressed at 100 - 200 °C and a pressure of 2 - 20 MPa for 10 - 70 min to make.

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