High-toughness polyurethane bulletproof material and injection molding process thereof

Abstract

The invention discloses a high-toughness polyurethane bulletproof material and an injection molding process thereof, and belongs to the technical field of bulletproof materials.The high-toughness polyurethane bulletproof material is prepared by the steps that a certain mass of composite antibacterial agent, modified antibacterial aramid fiber, polyurethane prepolymer, 4, 4 '-methylenebis (2-chloroaniline), dimethyl thio toluenediamine and antioxidant 1010 are mixed through a rheometer; quaternary ammonium ions in the composite antibacterial agent can adsorb pathogens, silver ions in the modified antibacterial aramid fibers can destroy cell membranes of microorganisms, and the composite antibacterial agent and the modified antibacterial aramid fibers have a certain synergistic effect in the aspect of improving the antibacterial performance of the high-toughness polyurethane bulletproof material. Silver ions are connected to the surfaces of the modified antibacterial aramid fibers through MOF, the slow release effect is achieved, the antibacterial aging of the high-toughness polyurethane bulletproof material can be prolonged, and when the high-toughness polyurethane bulletproof material is used as a bulletproof helmet lining, the long-acting antibacterial effect can be achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of bulletproof materials, and in particular relates to a high-toughness polyurethane bulletproof material and an injection molding process thereof. Background Art

[0002] With the upgrading of modern military and security protection needs, traditional bulletproof materials such as Kevlar fiber, ultra-high molecular weight polyethylene (UHMWPE) and metal armor have gradually exposed their limitations: although Kevlar fiber is lightweight, it has insufficient resistance to multiple impacts, UHMWPE is prone to adiabatic softening at high strain rates, and metal materials face problems such as heavy weight and poor flexibility. In this context, polyurethane (PU) materials have become the research and development focus of the new generation of bulletproof materials due to their unique microphase separation structure, high energy dissipation capacity and strong designability. However, the toughness (elongation at break is usually 300-500%) and anti-penetration performance of ordinary polyurethane are still difficult to meet high-level protection needs. To this end, in recent years, researchers have significantly improved the toughness and impact resistance of polyurethane by introducing nano-reinforced phases or dynamic cross-linked networks.

[0003] Chinese invention patent application publication number CN108673984A discloses a bullet-proof composite material, its preparation method, and application. In this material, the polyimide fiber accounts for 60%-90% by mass, and the resin matrix accounts for 10%-40% by mass. The polyimide fiber is modified using an inert modifier that undergoes an interface treatment. The inert modifier is a mixture of a water-based thermoplastic polyurethane and a water-based polyolefin resin in a specific proportion. The polyimide fiber is used as a reinforcement, undergoes a special interface treatment, is impregnated in the matrix resin in a specific arrangement, and is then composited with the matrix resin through a specific composite process. The resulting bullet-proof composite material exhibits high tensile strength and tensile modulus, good high and low temperature resistance, lightweight properties, good flame retardancy, and spinnability.

[0004] Aramid fiber or polyimide fiber is added to bulletproof materials to enhance their mechanical properties. However, when the bulletproof material polyurethane is used as the lining of a bulletproof helmet, it needs to come into direct contact with the person's scalp. When a person runs, the scalp will sweat profusely, and the sweat will penetrate into the lining material of the bulletproof helmet. After a period of use, bacteria will grow inside the lining material. If antibacterial agents are directly added to the lining material, the antibacterial effect will be limited. After a certain period of use, the antibacterial effect will decrease, and an odor will be generated. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-toughness polyurethane bullet-proof material and its injection molding process. The material is obtained by adding a composite antibacterial agent and a modified antibacterial aramid fiber to a polyurethane composite material and then undergoing an injection molding process, thereby improving the toughness and antibacterial properties of the material.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] An injection molding process for a high-toughness polyurethane bullet-proof material comprises the following steps:

[0008] Step 1: Compounding sodium montmorillonite and bis(trimethoxysilylpropyl)alkyl quaternary ammonium salt together through an ion exchange method to obtain a composite antibacterial agent.

[0009] Step 2: The chopped aramid fiber is surface-etched with dilute sulfuric acid to obtain surface-etched chopped aramid fiber, Ag-MOF is generated on the surface of the surface-etched chopped aramid fiber using a hydrothermal method to obtain antibacterial aramid fiber, and then the antibacterial aramid fiber is modified with hexamethylene diisocyanate to obtain modified antibacterial aramid fiber.

[0010] Step 3: Prepare a polyurethane prepolymer by a prepolymerization method, blend the polyurethane prepolymer, 4,4'-methylenebis(2-chloroaniline), dimethylthiotoluenediamine, antioxidant 1010, a composite antibacterial agent and modified antibacterial aramid fiber to obtain a polyurethane composite material, and injection mold the polyurethane composite material through a microporous foaming injection molding machine to obtain a high-toughness polyurethane bullet-proof material.

[0011] Furthermore, the preparation process of the composite antibacterial agent is as follows:

[0012] Sodium montmorillonite and deionized water are added to a reactor, stirred at 50-60°C and 300-500 r / min for 3-4 hours, bis(trimethoxysilylpropyl)alkyl quaternary ammonium salt and 50 vol% ethanol solution are dissolved with slight heat and then dripped into the reactor, and stirring is continued for 6-7 hours. The mixture is filtered, washed, dried, and ground to obtain a composite antibacterial agent.

[0013] Furthermore, the usage ratio of sodium montmorillonite, deionized water, bis(trimethoxysilylpropyl)alkyl quaternary ammonium salt and ethanol solution is 20-30 g: 300-400 mL: 12-15 g: 50-60 mL.

[0014] Furthermore, the preparation process of surface-etched chopped aramid fibers is as follows:

[0015] A 15wt% dilute sulfuric acid solution and short-cut aramid fibers with a diameter of 5-15 μm and a length of 1-3 mm are added into a reaction kettle, soaked for 48-50 hours, filtered, washed, and dried to obtain surface-etched short-cut aramid fibers.

[0016] Furthermore, the usage ratio of the dilute sulfuric acid solution to the chopped aramid fiber is 100-150 mL: 30-40 g.

[0017] Furthermore, the preparation process of antibacterial aramid fiber is as follows:

[0018] Silver nitrate, trimesic acid, imidazole, surface-etched short-cut aramid fiber and deionized water are added into a reactor, stirred at 500-800 r / min for 30-40 min, the pH value is adjusted to 6-7 with sodium hydroxide solution, reacted at 120-130° C. for 2-3 h, cooled, filtered, washed and dried to obtain antibacterial aramid fiber.

[0019] Furthermore, the usage ratio of silver nitrate, trimesic acid, imidazole, surface-etched chopped aramid fiber and deionized water is 25-30 g: 10-15 g: 20-25 g: 20-30 g: 1-1.2 L.

[0020] Furthermore, the preparation process of the modified antibacterial aramid fiber is as follows:

[0021] Antibacterial aramid fiber, hexamethylene diisocyanate and catalyst dibutyltin dilaurate are added to a reactor, reacted for 12-14 hours under nitrogen protection and 300-500 r / min, filtered and washed, and the precipitate and deionized water are added to the reactor, reacted for 12-14 hours, filtered and dried to obtain modified antibacterial aramid fiber.

[0022] Furthermore, the usage ratio of the antibacterial aramid fiber, hexamethylene diisocyanate and dibutyltin dilaurate is 20-30 g: 300-400 mL: 20-30 μL.

[0023] Furthermore, the preparation process of the high-toughness polyurethane bullet-proof material is as follows:

[0024] Polytetramethylene glycol and polycarbonate diol are added to a reactor, dehydrated at 120-130°C for 2-3 hours, and after cooling, dicyclohexylmethane diisocyanate is added, and the mixture is reacted at 90-100°C for 4-5 hours to obtain a polyurethane prepolymer. The polyurethane prepolymer, 4,4'-methylenebis(2-chloroaniline), dimethylthiotoluenediamine and antioxidant 1010 are added to a rheometer, melted at 190-195°C for 3-5 minutes, and a composite antibacterial agent and modified antibacterial aramid fiber are added, mixed for 4-5 minutes, and opened to obtain a polyurethane composite material. The composite material is then placed in a microporous foam injection molding machine, and supercritical nitrogen with a pressure of 10-11 MPa is injected through a supercritical fluid device. The composite material is then injected into a mold for foaming, and is formed after cooling and demolding to obtain a high-toughness polyurethane bullet-proof material.

[0025] Furthermore, the mass ratio of polytetramethylene glycol, polycarbonate diol, dicyclohexylmethane diisocyanate, 4,4'-methylenebis(2-chloroaniline), dimethylthiotoluene diamine, antioxidant 1010, composite antibacterial agent and modified antibacterial aramid fiber is 45-55:45-55:65-70:8-12:15-23:0.1-0.2:3-5:5-7.

[0026] Beneficial effects of the present invention:

[0027] 1. The high-toughness polyurethane bullet-proof material of the present invention is prepared by mixing a certain mass of a composite antibacterial agent, modified antibacterial aramid fiber, polyurethane prepolymer, 4,4'-methylenebis(2-chloroaniline), dimethylthiotoluenediamine and antioxidant 1010 through a rheometer and then through an injection molding process. The quaternary ammonium ions in the composite antibacterial agent can adsorb pathogens, and the silver ions in the modified antibacterial aramid fiber can destroy the cell membrane of microorganisms. The two play a certain synergistic role in improving the antibacterial performance of the high-toughness polyurethane bullet-proof material. In addition, the silver ions are connected to the surface of the modified antibacterial aramid fiber through MOF, playing a sustained-release role, which can prolong the antibacterial effect of the high-toughness polyurethane bullet-proof material. When used as the lining of a bulletproof helmet, it can play a long-lasting antibacterial effect.

[0028] 2. The modified antibacterial aramid fiber in the present invention is first acid-etched on the surface of the chopped aramid fiber with dilute sulfuric acid, thereby increasing the surface area of ​​the chopped aramid fiber and improving the surface roughness. Ag-MOF is then produced on the surface of the chopped aramid fiber by a hydrothermal method. The increase in surface roughness provides more growth space for MOF, increases the loading rate of Ag-MOF on the surface-etched chopped aramid fiber, and uniformly distributes silver ions on its surface. Hexamethylene diisocyanate is then grafted onto the antibacterial aramid fiber, which then reacts with water to form amino groups, forming chemical bonds with the polyurethane matrix. In addition, the increase in roughness also strengthens the mechanical interlocking with the polyurethane matrix, thereby improving the interfacial bonding force and thus improving the tensile strength and interlaminar shear strength of the high-toughness polyurethane bullet-proof material. Injection molding is performed with supercritical nitrogen to form a uniform closed-cell structure inside the material, thereby improving the impact resistance of the high-toughness polyurethane bullet-proof material.

[0029] 3. The composite antibacterial agent among the present invention utilizes ion exchange method that quaternary ammonium root ions and the sodium ions in sodium montmorillonite are exchanged, thereby quaternary ammonium salt is inserted in the layered structure of montmorillonite, increases interlaminar spacing, reduces reunion, and the layered structure of montmorillonite also can reduce the volatilization and loss of quaternary ammonium salt, prolongs antibacterial time effect, in addition, long-chain quaternary ammonium salt is inserted into the interlayer of montmorillonite, makes montmorillonite become hydrophobicity by hydrophilicity, is close to the polarity of polyurethane matrix, reduces two-phase interfacial tension, strengthens the dispersibility of montmorillonite in polyurethane matrix, promotes the compatibility with polyurethane matrix, reduces reunion, in addition, the increase of interlaminar spacing is beneficial to polyurethane chain molecular intercalation, montmorillonite lamella can hinder polyurethane molecular chain slippage, increases tensile strength and elastic modulus of high-toughness polyurethane bullet-proof material. DETAILED DESCRIPTION

[0030] The following will be combined with specific embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described 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 are within the scope of protection of the present invention.

[0031] Example 1: This example provides a high-toughness polyurethane bullet-proof material, which is prepared by the following steps:

[0032] S1: Add 25g of sodium montmorillonite and 350mL of deionized water into a reactor, stir for 3.5h at 55℃ and 400r / min, dissolve 13.5g of bis(trimethoxysilylpropyl)alkyl quaternary ammonium salt and 55mL of 50vol% ethanol solution under slight heat and then drop into the reactor, continue stirring for 6.5h, the quaternary ammonium salt is inserted into the montmorillonite interlayer through ion exchange reaction, increasing the interlayer distance of montmorillonite, filter, wash the precipitate with 50vol% ethanol solution 6 times, dry to constant weight, grind, and pass through a 300-mesh sieve to obtain a composite antibacterial agent.

[0033] S2: 175 mL of a 15 wt% dilute sulfuric acid solution and 35 g of chopped aramid fibers with a diameter of 5-15 μm and a length of 1-3 mm were added to a reactor, soaked for 49 hours, washed with deionized water until neutral, and dried at 62.5°C to constant weight to obtain surface-etched chopped aramid fibers.

[0034] S3: Add 27.5g of silver nitrate, 12.5g of trimesic acid, 22.5g of imidazole, 25g of surface-etched short-cut aramid fiber and 1.1L of deionized water into the reactor, stir at 650r / min for 35min, adjust the pH value to 6.5 with sodium hydroxide solution, react at 125℃ for 2.5h, in situ generate Ag-MOF on the surface of the surface-etched short-cut aramid fiber, quickly cool for 30min, centrifuge and filter, wash the precipitate with deionized water and anhydrous ethanol 4 times respectively, and vacuum dry at 65℃ to constant weight to obtain antibacterial aramid fiber.

[0035] S4: 25 g of antibacterial aramid fiber, 350 mL of hexamethylene diisocyanate and 25 μL of dibutyltin dilaurate as a catalyst were added to a reactor, and the reaction was carried out under nitrogen protection and 400 r / min for 13 hours. The hexamethylene diisocyanate was grafted onto the antibacterial aramid fiber, filtered, and the precipitate was washed 4 times with hexane, and then washed once with acetone and deionized water respectively. The precipitate and deionized water were added to the reactor and reacted for 13 hours. The isocyanate reacted with water to form amino groups. The mixture was filtered and dried to constant weight to obtain modified antibacterial aramid fiber.

[0036] S5: Add 50g of polytetramethylene glycol and 50g of polycarbonate diol into a reactor, dehydrate at 125°C for 2.5h, add 67g of dicyclohexylmethane diisocyanate after cooling, and react at 95°C for 4.5h to obtain a polyurethane prepolymer. Add the polyurethane prepolymer, 10g of 4,4'-methylenebis(2-chloroaniline), 19g of dimethylthiotoluene diamine and 0.15g of antioxidant 1010 into a rheometer, melt at 192°C for 4min, add 4g of a composite antibacterial agent and 6g of a modified antibacterial aramid fiber, mix for 4.5min, and start refining to obtain a polyurethane composite material.

[0037] S6: The polyurethane composite material is placed in a microcellular foam injection molding machine, and supercritical nitrogen with a pressure of 10.5 MPa is injected through a supercritical fluid device. The supercritical nitrogen injection speed is 232.5 mm / s, and then injected into the mold for foaming. The mold temperature is 77.5°C. After cooling, the mold is formed and demolded to obtain a high-toughness polyurethane bullet-proof material.

[0038] Example 2: This example provides a high-toughness polyurethane bullet-proof material, which is prepared by the following steps:

[0039] S1: Add 20g of sodium montmorillonite and 300mL of deionized water into a reactor, stir for 3h at 50℃ and 300r / min, dissolve 12g of bis(trimethoxysilylpropyl)alkyl quaternary ammonium salt and 50mL of 50vol% ethanol solution with slight heat, and then drop them into the reactor. Continue stirring for 6h. The quaternary ammonium salt is inserted into the montmorillonite interlayer through ion exchange reaction, increasing the interlayer distance of the montmorillonite. Filter, wash the precipitate with 50vol% ethanol solution 5 times, dry to constant weight, grind, and pass through a 300-mesh sieve to obtain a composite antibacterial agent.

[0040] S2: 150 mL of a 15 wt% dilute sulfuric acid solution and 30 g of chopped aramid fibers with a diameter of 5-15 μm and a length of 1-3 mm were added to a reactor, soaked for 48 hours, washed with deionized water until neutral, and dried at 60°C to constant weight to obtain surface-etched chopped aramid fibers.

[0041] S3: Add 25g of silver nitrate, 10g of trimesic acid, 20g of imidazole, 20g of surface-etched short-cut aramid fiber and 1L of deionized water into the reactor, stir at 500r / min for 30min, adjust the pH value to 6 with sodium hydroxide solution, react at 120℃ for 2h, in situ generate Ag-MOF on the surface of the surface-etched short-cut aramid fiber, quickly cool for 30min, centrifuge and filter, wash the precipitate with deionized water and anhydrous ethanol three times respectively, and vacuum dry at 60℃ to constant weight to obtain antibacterial aramid fiber.

[0042] S4: Add 20 g of antibacterial aramid fiber, 300 mL of hexamethylene diisocyanate and 20 μL of dibutyltin dilaurate as a catalyst into a reactor, react for 12 hours under nitrogen protection and 300 r / min, graft hexamethylene diisocyanate onto the antibacterial aramid fiber, filter, wash the precipitate with hexane three times, and then wash it with acetone and deionized water once respectively. Add the precipitate and deionized water into the reactor and react for 12 hours. The isocyanate reacts with water to form amino groups. Filter and dry to constant weight to obtain modified antibacterial aramid fiber.

[0043] S5: Add 45g of polytetramethylene glycol and 45g of polycarbonate diol into a reactor, dehydrate at 120°C for 2h, add 65g of dicyclohexylmethane diisocyanate after cooling, and react at 90°C for 4h to obtain a polyurethane prepolymer. Add the polyurethane prepolymer, 8g of 4,4'-methylenebis(2-chloroaniline), 15g of dimethylthiotoluene diamine and 0.1g of antioxidant 1010 into a rheometer, melt at 190°C for 3min, add 3g of a composite antibacterial agent and 5g of modified antibacterial aramid fiber, mix for 4min, and start refining to obtain a polyurethane composite material.

[0044] S6: The polyurethane composite material is placed in a microcellular foam injection molding machine, and supercritical nitrogen with a pressure of 10 MPa is injected through a supercritical fluid device. The supercritical nitrogen injection speed is 230 mm / s, and then injected into the mold for foaming. The mold temperature is 75°C. After cooling, the mold is formed and demolded to obtain a high-toughness polyurethane bullet-proof material.

[0045] Example 3: This example provides a high-toughness polyurethane bullet-proof material, which is prepared by the following steps:

[0046] S1: Add 30g of sodium montmorillonite and 400mL of deionized water into a reactor, stir at 60℃ and 500r / min for 4h, dissolve 15g of bis(trimethoxysilylpropyl)alkyl quaternary ammonium salt and 60mL of 50vol% ethanol solution under slight heat and then drop into the reactor, continue stirring for 7h, the quaternary ammonium salt is inserted into the montmorillonite interlayer through ion exchange reaction, increasing the interlayer distance of montmorillonite, filter, wash the precipitate with 50vol% ethanol solution 7 times, dry to constant weight, grind, and pass through a 300-mesh sieve to obtain a composite antibacterial agent.

[0047] S2: Add 200 mL of 15 wt% dilute sulfuric acid solution and 40 g of chopped aramid fibers with a diameter of 5-15 μm and a length of 1-3 mm into a reactor, soak for 50 hours, wash with deionized water until neutral, and dry at 65°C to constant weight to obtain surface-etched chopped aramid fibers.

[0048] S3: Add 30g of silver nitrate, 15g of trimesic acid, 25g of imidazole, 30g of surface-etched short-cut aramid fiber and 1.2L of deionized water into the reactor, stir at 800r / min for 40min, adjust the pH value to 7 with sodium hydroxide solution, react at 130℃ for 3h, in situ generate Ag-MOF on the surface of the surface-etched short-cut aramid fiber, quickly cool for 30min, centrifuge and filter, wash the precipitate with deionized water and anhydrous ethanol 5 times respectively, and vacuum dry at 70℃ to constant weight to obtain antibacterial aramid fiber.

[0049] S4: 30 g of antibacterial aramid fiber, 400 mL of hexamethylene diisocyanate and 30 μL of dibutyltin dilaurate as a catalyst were added to a reactor, and the mixture was reacted for 14 h under nitrogen protection and 500 r / min. The hexamethylene diisocyanate was grafted onto the antibacterial aramid fiber, filtered, and the precipitate was washed 5 times with hexane, and then washed once with acetone and deionized water respectively. The precipitate and deionized water were added to a reactor and reacted for 14 h. The isocyanate reacted with water to form amino groups. The mixture was filtered and dried to constant weight to obtain modified antibacterial aramid fiber.

[0050] S5: Add 55g of polytetramethylene glycol and 55g of polycarbonate diol into a reactor, dehydrate at 130°C for 3h, add 70g of dicyclohexylmethane diisocyanate after cooling, and react at 100°C for 5h to obtain a polyurethane prepolymer. Add the polyurethane prepolymer, 12g of 4,4'-methylenebis(2-chloroaniline), 23g of dimethylthiotoluene diamine and 0.2g of antioxidant 1010 into a rheometer, melt at 195°C for 5min, add 5g of a composite antibacterial agent and 7g of a modified antibacterial aramid fiber, mix for 5min, and start refining to obtain a polyurethane composite material.

[0051] S6: The polyurethane composite material is placed in a microcellular foam injection molding machine, and supercritical nitrogen with a pressure of 11 MPa is injected through a supercritical fluid device. The supercritical nitrogen injection speed is 235 mm / s, and then injected into the mold for foaming. The mold temperature is 80°C. After cooling, the mold is formed and demolded to obtain a high-toughness polyurethane bullet-proof material.

[0052] Comparative Example 1: Based on Example 1, the composite antibacterial agent was removed in step S5, and the remaining steps remained unchanged to prepare a high-toughness polyurethane bullet-proof material.

[0053] Comparative Example 2: Based on Example 1, the surface-etched chopped aramid fiber prepared in step S2 is used instead of the antibacterial aramid fiber in step S4, and the other steps remain unchanged to prepare a high-toughness polyurethane bullet-proof material.

[0054] Comparative Example 3: Based on Example 1, in step S5, the antibacterial aramid fiber prepared in step S3 is used instead of the modified antibacterial aramid fiber, and the other steps remain unchanged to prepare a high-toughness polyurethane bullet-proof material.

[0055] The high-toughness polyurethane bullet-proof materials in Examples 1 to 3 and Comparative Examples 1 to 3 were subjected to performance tests:

[0056] Mechanical properties: With reference to GB / T 528-2009, tensile testing was performed using an MZ-4000D electronic universal testing machine at a speed of 500 mm / min. The test result was the median of five measurements.

[0057] Dynamic Mechanical Properties: Storage modulus (-20°C) and loss factor (tan δ) were obtained using a TA-DMA242 DMA instrument. Testing was performed in tensile mode at a heating rate of 3°C / min.

[0058] Antibacterial properties: The high-toughness polyurethane bullet-proof material was tested for antibacterial properties against Staphylococcus aureus and Escherichia coli using the inhibition zone method. The specific experimental steps are as follows:

[0059] ① Sample preparation: Referring to QB / T 15979-2002, randomly select 8 points on the prepared high-toughness polyurethane bullet-proof material using a clean punch to cut discs with a diameter of approximately 6 mm. Place these discs together with a plastic culture dish under a sterile operating table and sterilize them with a UV lamp until ready for use.

[0060] ② Prepare culture medium and physiological saline: Prepare beef extract peptone agar culture medium and 0.9% physiological saline according to national standards, and pour them into bottles for later use.

[0061] ③Sterilization: Seal the prepared culture medium and physiological saline and place them together with the test tubes, conical flasks, pipette tips, tweezers, etc. used in the experiment into a high-pressure steam sterilizer for sterilization.

[0062] ④ Pour the plate: Pour about 15 mL of sterilized warm culture medium into the sterilized culture dish and let it stand horizontally to condense.

[0063] ⑤ Inoculate bacteria: Add 5 mL of saline to the culture tube and shake to remove any colonies on the slope of the tube. Use a pipette to draw 0.2 mL of the bacterial solution into the cooled plate and spread evenly with a spreading rod.

[0064] ⑥ Attach the sample: Use tweezers to place a circular sample on the surface of the culture medium. Set up three parallel sets for each sample. Place the labeled culture dish upside down in a 37°C incubator and incubate for 48 hours. Observe bacterial growth, measure the diameter of the inhibition zone, and calculate the average value.

[0065] The test results are shown in the following table:

[0066] Table 1 Performance test list

[0067]

[0068] As can be seen from Table 1, the tensile strength and elongation at break in Examples 1 to 3 are higher than those in Comparative Example 1 and Comparative Example 3. In step S5 of Comparative Example 1, the composite antibacterial agent is removed, and in step S4 of Comparative Example 3, the surface-etched chopped aramid fiber prepared in step S2 is used instead of the antibacterial aramid fiber, indicating that the modified antibacterial aramid fiber modified with hexamethylene diisocyanate and the composite antibacterial agent synergistically increase the mechanical properties of the high-toughness polyurethane bullet-proof material. This may be because the amino groups on the modified antibacterial aramid fiber form a chemical bond with the polyurethane matrix, and the long chain structure in the composite antibacterial agent is physically entangled with the molecular chains of the polyurethane matrix, thereby increasing the mechanical properties of the material.

[0069] As shown in Table 1, the storage modulus in Examples 1 to 3 is greater than that in Comparative Example 1 and Comparative Example 3. In step S5 of Comparative Example 1, the composite antibacterial agent is removed, and in step S4 of Comparative Example 3, the surface-etched short-cut aramid fiber prepared in step S2 is used instead of the antibacterial aramid fiber, which shows that the modified antibacterial aramid fiber and the composite antibacterial agent synergistically improve the toughness and impact resistance of the high-toughness polyurethane bullet-proof material.

[0070] As can be seen from Table 1, the diameters of the inhibition zones of Escherichia coli and Staphylococcus aureus in Examples 1 to 3 are larger than those in Comparative Example 1 and Comparative Example 2. The composite antibacterial agent is removed in step S5 of Comparative Example 1, and the surface-etched chopped aramid fiber prepared in step S2 is used instead of the antibacterial aramid fiber in step S4 of Comparative Example 2. This indicates that the composite antibacterial agent and the antibacterial aramid fiber with Ag-MOF have a certain synergistic effect in improving the antibacterial properties of high-toughness polyurethane bullet-proof materials.

[0071] It should be noted that, in this document, terms such as "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements that are inherent to such process, method, article or apparatus.

[0072] While the embodiments of the present invention have been shown and described, it will be apparent to those skilled in the art that various changes, modifications, substitutions, and alterations can be made to the embodiments without departing from the principles and spirit of the invention.

Claims

1. An injection molding process for a high-toughness polyurethane bullet-proof material, characterized in that: The steps include: Step 1: Compounding sodium montmorillonite and bis(trimethoxysilylpropyl)alkyl quaternary ammonium salt by ion exchange to obtain a composite antibacterial agent; Step 2: Surface etching the chopped aramid fiber with dilute sulfuric acid to obtain surface-etched chopped aramid fiber, generating Ag-MOF on the surface of the surface-etched chopped aramid fiber by a hydrothermal method to obtain antibacterial aramid fiber, and then modifying the antibacterial aramid fiber with hexamethylene diisocyanate to obtain modified antibacterial aramid fiber; Step 3: Prepare a polyurethane prepolymer by a prepolymerization method, blend the polyurethane prepolymer, 4,4'-methylenebis(2-chloroaniline), dimethylthiotoluenediamine, antioxidant 1010, a composite antibacterial agent and modified antibacterial aramid fiber to obtain a polyurethane composite material, and injection mold the polyurethane composite material through a microporous foaming injection molding machine to obtain a high-toughness polyurethane bullet-proof material.

2. The injection molding process of a high-toughness polyurethane bullet-proof material according to claim 1, characterized in that: The preparation process of the composite antibacterial agent in step 1 is as follows: Sodium montmorillonite and deionized water are added to a reactor, stirred at 50-60°C and 300-500 r / min for 3-4 hours, bis(trimethoxysilylpropyl)alkyl quaternary ammonium salt and 50 vol% ethanol solution are dissolved with slight heat and then dripped into the reactor, and stirring is continued for 6-7 hours. The mixture is filtered, washed, dried, and ground to obtain a composite antibacterial agent.

3. The injection molding process of a high-toughness polyurethane bullet-proof material according to claim 2, characterized in that: The dosage ratio of the sodium montmorillonite, deionized water, bis(trimethoxysilylpropyl)alkyl quaternary ammonium salt and ethanol solution is 20-30 g: 300-400 mL: 12-15 g: 50-60 mL.

4. The injection molding process of a high-toughness polyurethane bullet-proof material according to claim 1, characterized in that: The preparation process of the surface-etched chopped aramid fiber in step 2 is as follows: Adding a 15 wt% dilute sulfuric acid solution and short-cut aramid fibers with a diameter of 5-15 μm and a length of 1-3 mm into a reactor, soaking for 48-50 hours, filtering, washing, and drying to obtain surface-etched short-cut aramid fibers; The usage ratio of the dilute sulfuric acid solution to the chopped aramid fiber is 100-150 mL: 30-40 g.

5. The injection molding process of a high-toughness polyurethane bullet-proof material according to claim 1, characterized in that: The preparation process of the antibacterial aramid fiber in step 2 is as follows: Silver nitrate, trimesic acid, imidazole, surface-etched short-cut aramid fiber and deionized water are added into a reactor, stirred at 500-800 r / min for 30-40 min, the pH value is adjusted to 6-7 with sodium hydroxide solution, reacted at 120-130° C. for 2-3 h, cooled, filtered, washed and dried to obtain antibacterial aramid fiber.

6. The injection molding process of a high-toughness polyurethane bullet-proof material according to claim 5, characterized in that: The usage ratio of the silver nitrate, trimesic acid, imidazole, surface-etched chopped aramid fiber and deionized water is 25-30 g: 10-15 g: 20-25 g: 20-30 g: 1-1.2 L.

7. The injection molding process of a high-toughness polyurethane bullet-proof material according to claim 1, characterized in that: The preparation process of the modified antibacterial aramid fiber in step 2 is as follows: Antibacterial aramid fiber, hexamethylene diisocyanate and catalyst dibutyltin dilaurate are added to a reactor, reacted for 12-14 hours under nitrogen protection and 300-500 r / min, filtered and washed, and the precipitate and deionized water are added to the reactor, reacted for 12-14 hours, filtered and dried to obtain modified antibacterial aramid fiber.

8. The injection molding process of a high-toughness polyurethane bullet-proof material according to claim 7, characterized in that: The usage ratio of the antibacterial aramid fiber, hexamethylene diisocyanate and dibutyltin dilaurate is 20-30 g: 300-400 mL: 20-30 μL.

9. The injection molding process of a high-toughness polyurethane bullet-proof material according to claim 1, characterized in that: The preparation process of the high-toughness polyurethane bullet-proof material in step 3 is as follows: Adding polytetrahydrofuran diol and polycarbonate diol to a reactor, dehydrating at 120-130° C. for 2-3 hours, adding dicyclohexylmethane diisocyanate after cooling, reacting at 90-100° C. for 4-5 hours to obtain a polyurethane prepolymer, adding the polyurethane prepolymer, 4,4'-methylenebis(2-chloroaniline), dimethylthiotoluenediamine and antioxidant 1010 to a rheometer, melting at 190-195° C. for 3-5 minutes, adding a composite antibacterial agent and modified antibacterial aramid fiber, mixing for 4-5 minutes, and refining to obtain a polyurethane composite material, which is then placed in a microporous foam injection molding machine, injected with supercritical nitrogen at a pressure of 10-11 MPa through a supercritical fluid device, and then injected into a mold for foaming, formed after cooling, and demolded to obtain a high-toughness polyurethane bullet-proof material; The mass ratio of the polytetramethylene glycol, polycarbonate diol, dicyclohexylmethane diisocyanate, 4,4'-methylenebis(2-chloroaniline), dimethylthiotoluenediamine, antioxidant 1010, composite antibacterial agent and modified antibacterial aramid fiber is 45-55:45-55:65-70:8-12:15-23:0.1-0.2:3-5:5-7.

10. A high-toughness polyurethane bullet-proof material, characterized in that: The high-toughness polyurethane bullet-proof material is prepared by the injection molding process according to any one of claims 1 to 9.

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