Flame resistant nylon material for protective face masks and method of making the same

Abstract

This invention relates to the field of polymer materials technology, and discloses a flame-retardant nylon material for protective face shields and its preparation method. The flame-retardant nylon material of this invention comprises the following raw materials in parts by weight: 50-65 parts nylon 66 resin, 5-15 parts montmorillonite, 3-7 parts Zr-MOF-PS, 4-8 parts modified toughening agent, 0.1-0.5 parts antioxidant, 0.1-0.4 parts light stabilizer, 0.2-0.5 parts heat stabilizer, 0.2-0.6 parts bis-stearamide, and 0.3-0.8 parts isopropyltriethoxysilane. The Zr-MOF-PS of this invention can improve the flame-retardant properties of the nylon matrix, forming a dense and stable char layer upon contact with fire to block the spread of flames, while effectively inhibiting the release of toxic fumes. The modified toughening agent can improve the impact resistance and bending resistance of the protective face shield, effectively preventing problems such as cracking, breakage, and deformation.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a flame-retardant nylon material for protective face shields and its preparation method. Background Technology

[0002] Protective face shields are core individual facial protection equipment in industrial production, emergency rescue, and other scenarios, and are widely used in high-risk operations such as fire rescue, chemical production, electrical maintenance, and metal welding. This equipment possesses excellent impact resistance, puncture resistance, stable flame retardancy and fire resistance, and anti-molten dripping properties, while also considering dimensional stability, corrosion resistance, and processability. Nylon 66 is the preferred matrix material for protective face shield products. Compared with general nylon materials, PA66 has higher mechanical strength, flexural modulus, and impact toughness, which can fully match the core requirements of protective face shields for structural rigidity and deformation resistance. However, it is itself a flammable material, and during combustion, it easily produces continuous melting and dripping, accompanied by a large amount of toxic fumes and heat release, completely failing to meet the flame retardant safety standards for protective face shields in high-risk operation scenarios. In existing technologies, flame retardant modification of PA66 mainly uses halogenated flame retardants, phosphorus-nitrogen flame retardants, and inorganic metal hydroxide flame retardants. Halogenated flame retardants are strictly restricted due to their potential to cause harm to humans and environmental pollution. While halogen-free phosphorus and nitrogen-based and inorganic flame retardants meet environmental protection requirements, their flame-retardant efficiency is limited when used in a single system, and high levels of these retardants can significantly reduce the material's core mechanical properties, such as tensile strength and impact toughness. Furthermore, high-end protective face mask products have stringent requirements for the tensile strength and impact toughness of materials. Therefore, how to simultaneously improve the flame retardancy and mechanical properties of PA66 has become a pressing technical problem to be solved in this field.

[0003] Patent application number 201210197562.0 discloses a flame-retardant conductive nylon composite material, using decabromodiphenyl ethane as a flame retardant to improve the flame retardancy of the nylon matrix. However, it has potential toxicity to aquatic organisms, produces a large amount of smoke during the flame retardant process, has poor flame retardant durability, and limited functionality. Patent application number 202310309341.6 discloses a halogen-free flame-retardant nylon material and its preparation method, using red phosphorus flame-retardant masterbatch or hypophosphite flame-retardant masterbatch as a halogen-free flame retardant. This is environmentally friendly, but red phosphorus affects the color of the product and has poor compatibility with the substrate, easily precipitating out. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a flame-retardant nylon material for protective face shields and its preparation method.

[0005] The objective of this invention can be achieved through the following technical solutions: A flame-retardant nylon material for protective face shields comprises the following raw materials in parts by weight: 50-65 parts nylon 66 resin, 5-15 parts montmorillonite, 3-7 parts Zr-MOF-PS, 4-8 parts modified toughening agent, 0.1-0.5 parts antioxidant, 0.1-0.4 parts light stabilizer, 0.2-0.5 parts heat stabilizer, 0.2-0.6 parts bis-stearamide, and 0.3-0.8 parts isopropyltriethoxysilane; The antioxidant is at least one of antioxidant 1098 and antioxidant 168; The light stabilizer is at least one of UV234, UV360, and TFB117; The heat stabilizer is at least one of calcium stearate, heat stabilizer H3336, and heat stabilizer S-EED; The Zr-MOF-PS is prepared by the following steps: Step A1: Mix bisphenol S and N,N-dimethylformamide (DMF), add aluminum trichloride, stir at room temperature for 30 min, then add phenyl phosphorus dichloride dropwise over 1 h. After the addition is complete, heat to 60 °C, react for 4 h, and then evaporate by rotary evaporation to obtain intermediate product 1. Furthermore, the ratio of bisphenol S, DMF, aluminum trichloride, and phenyl phosphorus dichloride is 0.1-0.3 mol : 100-250 mL : 0.005-0.015 mol : 0.22-0.66 mol; In step A1, bisphenol S and phenyl phosphorus dichloride undergo a phosphorylation reaction. The remaining unreacted P-Cl bonds provide reaction conditions for subsequent phosphorylation reactions. The introduced phosphorus-containing structure decomposes upon heating to generate phosphoric acid, metaphosphoric acid, polymetaphosphoric acid, and other strongly dehydrating substances, which promote polymer dehydration and form a dense char layer. At the same time, it can also capture active free radicals in the combustion chain reaction, interrupt the chain reaction, and work synergistically with sulfur to promote the formation of a more stable char layer. This comprehensively inhibits the chain reaction and improves the flame retardant efficiency.

[0006] Step A2: Mix intermediate product 1 and DMF, heat to 50°C in an oil bath, stir, add p-aminobenzoic acid, heat to 80°C, react for 4 hours, filter under reduced pressure, wash, and dry under vacuum to obtain intermediate product 2. Furthermore, the ratio of intermediate 1, DMF, and p-aminobenzoic acid is 0.08-0.12 mol: 80-120 mL: 0.176-0.264 mol; In step A2, intermediate product 1 and p-aminobenzoic acid undergo a phosphorylation reaction, introducing a carboxyl group into the system to provide reaction conditions for subsequent reactions.

[0007] Step A3: Mix zirconium tetrachloride, biphenyl dicarboxylic acid and DMF, add glacial acetic acid, and then transfer to a high-pressure reactor. Stir at room temperature for 30 min, then place the reactor in a 120°C oven and heat for 36 h. After the reactor cools to room temperature, take out the sample, wash and dry it to obtain intermediate product 3. Furthermore, the ratio of zirconium tetrachloride, biphenyl dicarboxylic acid, DMF and glacial acetic acid is 1-2 mmol: 1-2 mmol: 100-200 mL: 7-14 mL; In step A3, zirconium tetrachloride and biphenyl dicarboxylic acid generate zirconium-based metal-organic framework (Zr-MOF) through coordination-driven self-assembly reaction. The porous structure formed by its pyrolysis helps to form a carbon layer, which isolates heat transfer and reduces the release of toxic gases. The large specific surface area and regular porous structure of Zr-MOF can delay the release of volatiles by forming tortuous paths, thereby inhibiting the generation of smoke.

[0008] Step A4: Mix intermediate product 3 with anhydrous ethanol, add intermediate product 2 solution, stir at 60℃ for 1 h, after the reaction is complete, centrifuge, wash and dry to obtain P / S modified zirconium-based metal-organic framework material (Zr-MOF-PS). Furthermore, the ratio of intermediate product 3, anhydrous ethanol, and intermediate product 2 solution is 1g:80-100mL:80-100mL; Furthermore, the intermediate product 2 solution is prepared by mixing intermediate product 2 and anhydrous ethanol at a volume ratio of 0.4-0.5 mmol: 80-100 mL; In step A4, the carboxyl group in intermediate product 2 modifies the Zr-MOF surface by coordinating with the zirconium cluster in Zr-MOF. The P and S organic ligands improve the compatibility and dispersibility of Zr-MOF in the polymer matrix, thereby enhancing the flame retardant performance. The free radicals generated by the decomposition of the ligands can quench oxygen free radicals. MOF has the characteristics of smoke suppression, heat insulation and catalytic char formation. The two work synergistically to improve the flame retardant efficiency of the nylon matrix.

[0009] The modified toughening agent is prepared by the following steps: Step B1: Mix m-phenylenediamine, sebacic acid, 2,5-furandicarboxylic acid, deionized water and antioxidant 1098 and add them to the polymerization reactor. Seal the reactor, introduce nitrogen gas, raise the temperature to 150°C, stir and react for 30 min, then raise the temperature to 200°C and react for 2 h. Release the pressure of the reactor to atmospheric pressure, take out the product, and vacuum dry it to obtain carboxyl-terminated polyamide. Furthermore, the ratio of m-phenylenediamine, sebacic acid, 2,5-furandicarboxylic acid, deionized water, and antioxidant 1098 is 0.1-0.2 mol: 0.1-0.2 mol: 0.1-0.2 mol: 4.5-9 g: 0.009-0.018 g; In step B1, m-phenylenediamine undergoes an amidation polycondensation reaction with sebacic acid and 2,5-furandicarboxylic acid, introducing carboxyl groups into the system and providing reaction conditions for the subsequent ring-opening reaction. The resulting polyamide contains a large number of benzene rings and furan ring structures, which can improve the rigidity and strength of the system. The amide bonds can improve the compatibility with the matrix and further enhance the mechanical properties of the system.

[0010] Step B2: Mix 2,3-epoxypropyltrimethylammonium chloride, carboxyl-terminated polyamide and DMF, purge with nitrogen, heat to 70°C using an oil bath, react for 20 hours, rotary evaporate, and vacuum dry to obtain the modified toughening agent. Furthermore, the ratio of 2,3-epoxypropyltrimethylammonium chloride, carboxyl-terminated polyamide, and DMF is 0.16-0.2 mol: 0.08-0.1 mol: 50-70 mL; In step B2, 2,3-epoxypropyltrimethylammonium chloride and carboxyl-terminated polyamide undergo a ring-opening reaction, introducing a quaternary ammonium salt into the system. The polar quaternary ammonium groups in its molecular structure can interact with nylon via electrostatic or hydrogen bonding, thereby enhancing the interfacial compatibility between the toughening agent and the nylon matrix, promoting more uniform dispersion and stronger interfacial adhesion, improving the impact strength of the matrix, and synergistically enhancing the tensile strength, flexural modulus, and impact strength of the matrix in conjunction with the polyamide chains. A method for preparing a flame-retardant nylon material for protective face shields includes the following steps: Step S1: Weigh the raw materials according to the weight parts, and thoroughly mix the nylon 66 resin, montmorillonite, Zr-MOF-PS, modified toughening agent, antioxidant, light stabilizer, heat stabilizer, bis-stearamide and isopropyltriethoxysilane to obtain a mixture. Step S2: Add the mixture to a twin-screw extruder, and after melting, extrusion, granulation, and drying, obtain the flame-retardant nylon material for protective face masks. The processing temperatures of each zone of the twin-screw extruder are as follows: Zone 1 180-190℃, Zone 2 190-200℃, Zone 3 210-220℃, Zone 4 220-230℃, Zone 5 220-230℃, Zone 6 220-230℃, Zone 7 220-230℃, Zone 8 220-230℃, and the die zone 220-230℃. The screw speed is 150-300 r / min.

[0011] The beneficial effects of this invention are: The flame-retardant nylon material for protective face shields of this invention can be widely used in the production and manufacturing of various professional protective face shields for industrial protection, fire emergency response, chemical operations, and other applications. Using the flame-retardant nylon material of this invention in the production of protective face shields can significantly improve the flame-retardant safety performance of the product. The use of Zr-MOF-PS enhances the flame-retardant properties of the nylon matrix, forming a dense and stable char layer upon contact with fire to block the spread of flames, while effectively inhibiting the release of toxic fumes and preventing the face shield from melting through during combustion and secondary injuries to users from harmful fumes. Simultaneously, relying on modified toughening agents, the impact resistance and bending resistance of the protective face shield are greatly improved, effectively preventing problems such as cracking, breakage, and deformation, maintaining structural integrity, and achieving long-lasting physical protection. Compared with existing technologies, this invention, through the synergistic modification system of Zr-MOF-PS and modified toughening agents, achieves a high level of flame retardancy without sacrificing the material's rigidity and toughness, while optimizing the material's impact resistance and processing adaptability, demonstrating broad application prospects and industrialization value.

[0012] The Zr-MOF-PS of this invention first utilizes bisphenol S and phenyl phosphorus dichloride to undergo a phosphorylation reaction. The introduced phosphorus-containing structure decomposes upon heating to generate strongly dehydrating substances such as phosphoric acid, metaphosphoric acid, and polymetaphosphoric acid, promoting polymer dehydration and forming a dense char layer. Simultaneously, it can capture active free radicals in the combustion chain reaction, interrupting the chain reaction. Synergistically with sulfur, it promotes the formation of a more stable char layer, comprehensively inhibiting the chain reaction and improving flame retardant efficiency. Subsequently, it undergoes a phosphorylation reaction with p-aminobenzoic acid to introduce carboxyl groups into the system. Zr-MOF material is generated through a coordination-driven self-assembly reaction between zirconium tetrachloride and biphenyl dicarboxylic acid. The porous structure formed by its pyrolysis facilitates the formation of a char layer, insulating heat transfer and reducing the release of toxic gases. The large specific surface area and regular porous structure of Zr-MOF can delay the release of volatiles by forming tortuous paths, thereby suppressing smoke generation. Finally, the carboxyl group in intermediate product 2 is used to modify the Zr-MOF surface through coordination with the zirconium cluster in Zr-MOF. The P and S organic ligands improve the compatibility and dispersibility of Zr-MOF in the polymer matrix, thereby enhancing the flame retardant performance. The free radicals generated by the decomposition of the ligands can quench oxygen free radicals. MOF has the characteristics of smoke suppression, heat insulation and catalytic char formation. The two work synergistically to improve the flame retardant efficiency of the nylon matrix.

[0013] The modified toughening agent of this invention first undergoes an amidation polycondensation reaction between m-phenylenediamine and sebacic acid and 2,5-furandicarboxylic acid. The resulting polyamide contains a large number of benzene rings and furan rings, which can improve the rigidity and strength of the system. The amide bonds can improve the compatibility with the matrix, further enhancing the mechanical properties of the system. Finally, it undergoes a ring-opening reaction with 2,3-epoxypropyltrimethylammonium chloride, introducing a quaternary ammonium salt into the system. The polar quaternary ammonium groups in its molecular structure can interact with nylon through electrostatic or hydrogen bonding, thereby enhancing the interfacial compatibility between the toughening agent and the nylon matrix, promoting more uniform dispersion and stronger interfacial adhesion, improving the impact strength of the matrix, and synergistically improving the tensile strength, flexural modulus, and impact strength of the matrix. Detailed Implementation

[0014] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] Example 1: Zr-MOF-PS was prepared by the following steps: Step A1: Mix bisphenol S and DMF, add aluminum trichloride, stir at room temperature for 30 min, then add phenyl phosphorus dichloride dropwise over 1 h. After the addition is complete, heat to 60 °C and react for 4 h. Then, evaporate by rotary evaporation to obtain intermediate product 1. The ratio of bisphenol S, DMF, aluminum trichloride and phenyl phosphorus dichloride is 0.1 mol: 100 mL: 0.005 mol: 0.22 mol. Step A2: Mix intermediate product 1 and DMF, heat to 50°C in an oil bath, stir, add p-aminobenzoic acid, heat to 80°C, react for 4 hours. After the reaction is complete, filter under reduced pressure, wash, and dry under vacuum to obtain intermediate product 2. The ratio of intermediate product 1, DMF and p-aminobenzoic acid is 0.08 mol: 80 mL: 0.176 mol. Step A3: Mix zirconium tetrachloride, biphenyl dicarboxylic acid, and DMF, add glacial acetic acid, and then transfer to a high-pressure reactor. Stir at room temperature for 30 min, then place the reactor in a 120°C oven and heat for 36 h. After the reactor cools to room temperature, remove the sample, wash and dry it to obtain intermediate product 3. The ratio of zirconium tetrachloride, biphenyl dicarboxylic acid, DMF, and glacial acetic acid is 1 mmol: 1 mmol: 100 mL: 7 mL. Step A4: Mix intermediate product 3 and anhydrous ethanol, add intermediate product 2 solution, stir at 60℃ for 1 h. After the reaction is complete, centrifuge, wash and dry to obtain Zr-MOF-PS. The ratio of intermediate product 3, anhydrous ethanol and intermediate product 2 solution is 1 g: 80 mL: 80 mL. Intermediate product 2 solution is prepared by mixing intermediate product 2 and anhydrous ethanol at a ratio of 0.4 mmol: 80 mL.

[0016] The modified toughening agent is prepared by the following steps: Step B1: Mix m-phenylenediamine, sebacic acid, 2,5-furandicarboxylic acid, deionized water, and antioxidant 1098 and add them to a polymerization reactor. Seal the reactor, introduce nitrogen gas, raise the temperature to 150°C, stir, and react for 30 min. Then raise the temperature to 200°C and react for 2 h. Release the pressure in the reactor to atmospheric pressure, remove the product, and vacuum dry it to obtain carboxyl-terminated polyamide. The ratio of m-phenylenediamine, sebacic acid, 2,5-furandicarboxylic acid, deionized water, and antioxidant 1098 is 0.1 mol: 0.1 mol: 0.1 mol: 4.5 g: 0.009 g. Step B2: Mix 2,3-epoxypropyltrimethylammonium chloride, carboxyl-terminated polyamide and DMF, purge with nitrogen, heat to 70°C using an oil bath, react for 20 hours, rotary evaporate, and vacuum dry to obtain the modified toughening agent. The ratio of 2,3-epoxypropyltrimethylammonium chloride, carboxyl-terminated polyamide and DMF is 0.16 mol: 0.08 mol: 50 mL.

[0017] Example 2: Zr-MOF-PS was prepared by the following steps: Step A1: Mix bisphenol S and DMF, add aluminum trichloride, stir at room temperature for 30 min, then add phenyl phosphorus dichloride dropwise over 1 h. After the addition is complete, heat to 60 °C and react for 4 h. Then, evaporate by rotary evaporation to obtain intermediate product 1. The ratio of bisphenol S, DMF, aluminum trichloride and phenyl phosphorus dichloride is 0.2 mol: 175 mL: 0.01 mol: 0.44 mol. Step A2: Mix intermediate product 1 and DMF, heat to 50°C in an oil bath, stir, add p-aminobenzoic acid, heat to 80°C, react for 4 hours, after the reaction is complete, filter under reduced pressure, wash, and dry under vacuum to obtain intermediate product 2. The ratio of intermediate product 1, DMF and p-aminobenzoic acid is 0.1 mol: 100 mL: 0.22 mol. Step A3: Mix zirconium tetrachloride, biphenyl dicarboxylic acid, and DMF, add glacial acetic acid, and then transfer to a high-pressure reactor. Stir at room temperature for 30 min, then place the reactor in a 120°C oven and heat for 36 h. After the reactor cools to room temperature, remove the sample, wash and dry it to obtain intermediate product 3. The ratio of zirconium tetrachloride, biphenyl dicarboxylic acid, DMF, and glacial acetic acid is 1.5 mmol: 1.5 mmol: 150 mL: 10.5 mL. Step A4: Mix intermediate product 3 and anhydrous ethanol, add intermediate product 2 solution, stir at 60℃ for 1 h. After the reaction is complete, centrifuge, wash and dry to obtain Zr-MOF-PS. The ratio of intermediate product 3, anhydrous ethanol and intermediate product 2 solution is 1 g: 90 mL: 90 mL. Intermediate product 2 solution is prepared by mixing intermediate product 2 and anhydrous ethanol at a ratio of 0.45 mmol: 90 mL.

[0018] The modified toughening agent is prepared by the following steps: Step B1: Mix m-phenylenediamine, sebacic acid, 2,5-furandicarboxylic acid, deionized water, and antioxidant 1098 and add them to a polymerization reactor. Seal the reactor, introduce nitrogen gas, raise the temperature to 150°C, stir, and react for 30 min. Then raise the temperature to 200°C and react for 2 h. Release the pressure in the reactor to atmospheric pressure, remove the product, and vacuum dry it to obtain carboxyl-terminated polyamide. The ratio of m-phenylenediamine, sebacic acid, 2,5-furandicarboxylic acid, deionized water, and antioxidant 1098 is 0.15 mol: 0.15 mol: 0.15 mol: 6.75 g: 0.0135 g. Step B2: Mix 2,3-epoxypropyltrimethylammonium chloride, carboxyl-terminated polyamide and DMF, purge with nitrogen, heat to 70°C using an oil bath, react for 20 hours, rotary evaporate, and vacuum dry to obtain the modified toughening agent. The ratio of 2,3-epoxypropyltrimethylammonium chloride, carboxyl-terminated polyamide and DMF is 0.18 mol: 0.09 mol: 60 mL.

[0019] Example 3: Zr-MOF-PS was prepared by the following steps: Step A1: Mix bisphenol S and DMF, add aluminum trichloride, stir at room temperature for 30 min, then add phenyl phosphorus dichloride dropwise over 1 h. After the addition is complete, heat to 60 °C and react for 4 h. Then, evaporate by rotary evaporation to obtain intermediate product 1. The ratio of bisphenol S, DMF, aluminum trichloride and phenyl phosphorus dichloride is 0.3 mol: 250 mL: 0.015 mol: 0.66 mol. Step A2: Mix intermediate product 1 and DMF, heat to 50°C in an oil bath, stir, add p-aminobenzoic acid, heat to 80°C, react for 4 hours. After the reaction is complete, filter under reduced pressure, wash, and dry under vacuum to obtain intermediate product 2. The ratio of intermediate product 1, DMF and p-aminobenzoic acid is 0.12 mol: 120 mL: 0.264 mol. Step A3: Mix zirconium tetrachloride, biphenyl dicarboxylic acid, and DMF, add glacial acetic acid, and then transfer to a high-pressure reactor. Stir at room temperature for 30 min, then place the reactor in a 120°C oven and heat for 36 h. After the reactor cools to room temperature, remove the sample, wash and dry it to obtain intermediate product 3. The ratio of zirconium tetrachloride, biphenyl dicarboxylic acid, DMF, and glacial acetic acid is 2 mmol: 2 mmol: 200 mL: 14 mL. Step A4: Mix intermediate product 3 and anhydrous ethanol, add intermediate product 2 solution, stir at 60℃ for 1 h. After the reaction is complete, centrifuge, wash and dry to obtain Zr-MOF-PS. The ratio of intermediate product 3, anhydrous ethanol and intermediate product 2 solution is 1 g: 100 mL: 100 mL. Intermediate product 2 solution is prepared by mixing intermediate product 2 and anhydrous ethanol at a ratio of 0.5 mmol: 100 mL.

[0020] The modified toughening agent is prepared by the following steps: Step B1: Mix m-phenylenediamine, sebacic acid, 2,5-furandicarboxylic acid, deionized water, and antioxidant 1098 and add them to the polymerization reactor. Seal the reactor, introduce nitrogen gas, raise the temperature to 150°C, stir, and react for 30 min. Then raise the temperature to 200°C and react for 2 h. Release the pressure in the reactor to atmospheric pressure, remove the product, and vacuum dry it to obtain carboxyl-terminated polyamide. The ratio of m-phenylenediamine, sebacic acid, 2,5-furandicarboxylic acid, deionized water, and antioxidant 1098 is 0.2 mol: 0.2 mol: 0.2 mol: 9 g: 0.018 g. Step B2: Mix 2,3-epoxypropyltrimethylammonium chloride, carboxyl-terminated polyamide and DMF, purge with nitrogen, heat to 70°C using an oil bath, react for 20 hours, rotary evaporate, and vacuum dry to obtain the modified toughening agent. The ratio of 2,3-epoxypropyltrimethylammonium chloride, carboxyl-terminated polyamide and DMF is 0.2 mol: 0.1 mol: 70 mL.

[0021] Example 4: A method for preparing a flame-retardant nylon material for protective face shields, comprising the following steps: 50 parts of Nylon 66 resin, 5 parts of montmorillonite, 3 parts of Zr-MOF-PS prepared in Example 1, 4 parts of modified toughening agent prepared in Example 1, 0.1 parts of antioxidant 1098, 0.1 parts of UV234, 0.2 parts of calcium stearate, 0.2 parts of bis-stearamide, and 0.3 parts of isopropyltriethoxysilane; Step S1: Weigh the raw materials according to the weight parts, and thoroughly mix the nylon 66 resin, montmorillonite, Zr-MOF-PS prepared in Example 1, modified toughening agent prepared in Example 1, antioxidant 1098, UV234, calcium stearate, bis-stearamide and isopropyltriethoxysilane to obtain a mixture. Step S2: Add the mixture to a twin-screw extruder, and after melting, extrusion, granulation, and drying, obtain the flame-retardant nylon material for protective face shields. The processing temperatures of each zone of the twin-screw extruder are as follows: Zone 1 180℃, Zone 2 190℃, Zone 3 210℃, Zone 4 220℃, Zone 5 220℃, Zone 6 220℃, Zone 7 220℃, Zone 8 220℃, and the die zone 220℃. The screw speed is 150 r / min.

[0022] Example 5: A method for preparing a flame-retardant nylon material for protective face shields, comprising the following steps: 60 parts of Nylon 66 resin, 10 parts of montmorillonite, 5 parts of Zr-MOF-PS prepared in Example 2, 6 parts of modified toughening agent prepared in Example 2, 0.3 parts of antioxidant 168, 0.3 parts of UV360, 0.3 parts of heat stabilizer H3336, 0.4 parts of bis-stearamide, and 0.5 parts of isopropyltriethoxysilane; Step S1: Weigh the raw materials according to the weight parts, and thoroughly mix the nylon 66 resin, montmorillonite, Zr-MOF-PS prepared in Example 2, modified toughening agent prepared in Example 2, antioxidant 168, UV360, heat stabilizer H3336, bis-stearamide and isopropyltriethoxysilane to obtain a mixture. Step S2: Add the mixture to a twin-screw extruder, and after melting, extrusion, granulation, and drying, obtain the flame-retardant nylon material for protective face shields. The processing temperatures of each zone of the twin-screw extruder are as follows: Zone 1 185℃, Zone 2 195℃, Zone 3 215℃, Zone 4 225℃, Zone 5 225℃, Zone 6 225℃, Zone 7 225℃, Zone 8 225℃, and the die zone 225℃. The screw speed is 200 r / min.

[0023] Example 6: A method for preparing a flame-retardant nylon material for protective face shields, comprising the following steps: 65 parts of Nylon 66 resin, 15 parts of montmorillonite, 7 parts of Zr-MOF-PS prepared in Example 3, 8 parts of modified toughening agent prepared in Example 3, 0.2 parts of antioxidant 1098, 0.3 parts of antioxidant 168, 0.2 parts of UV360, 0.2 parts of TFB117, 0.2 parts of heat stabilizer H3336, 0.3 parts of heat stabilizer S-EED, 0.6 parts of bis-stearamide, and 0.8 parts of isopropyltriethoxysilane; Step S1: Weigh the raw materials according to the weight parts, and thoroughly mix the nylon 66 resin, montmorillonite, Zr-MOF-PS prepared in Example 3, modified toughening agent prepared in Example 3, antioxidant 1098, antioxidant 168, UV360, TFB117, heat stabilizer H3336, heat stabilizer S-EED, bis-stearamide and isopropyltriethoxysilane to obtain a mixture. Step S2: Add the mixture to a twin-screw extruder, and after melting, extrusion, granulation, and drying, obtain the flame-retardant nylon material for protective face shields. The processing temperatures of each zone of the twin-screw extruder are as follows: Zone 1 190℃, Zone 2 200℃, Zone 3 220℃, Zone 4 230℃, Zone 5 230℃, Zone 6 230℃, Zone 7 230℃, Zone 8 230℃, and the die zone 230℃. The screw speed is 300 r / min.

[0024] Comparative Example 1: This comparative example is a nylon material. The difference between this example and Example 6 is that magnesium hydroxide is used instead of the Zr-MOF-PS prepared in Example 3. All other aspects are the same.

[0025] Comparative Example 2: This comparative example is a nylon material. The difference between this example and Example 6 is that maleic anhydride-grafted polyethylene is used instead of the modified toughening agent prepared in Example 3. All other aspects are the same.

[0026] Comparative Example 3: This comparative example is a nylon material. The difference between this example and Example 6 is that magnesium hydroxide is used instead of the Zr-MOF-PS prepared in Example 3, and maleic anhydride-grafted polyethylene is used instead of the modified toughening agent prepared in Example 3. All other aspects are the same.

[0027] The nylon materials prepared in Examples 4-6 and Comparative Examples 1-3 were subjected to performance tests: Tensile strength: Tested according to GB / T 1040; Bending strength: Tested according to GB / T 9341; Notched impact strength: Tested according to GB / T 1043; Flame retardancy: Flammability was tested according to UL94 standard; Limiting oxygen index: Tested according to GB / T 2406 standard.

[0028] The test results are shown in Table 1: Table 1: Performance Test Results

[0029] As can be seen from Table 1, the flame-retardant nylon material for protective face shields prepared by this invention has excellent mechanical properties and flame-retardant characteristics. The tensile strength of the nylon materials prepared in the examples is above 131 MPa, the flexural strength is above 204 MPa, and the notched impact strength is above 12 KJ / m. 2 As shown in Example 6 and Comparative Example 1, the Zr-MOF-PS prepared by this invention improves the flame retardant properties of the nylon matrix, with all examples achieving a flame retardant rating of V-0. As shown in Example 6 and Comparative Example 2, the modified toughening agent of this invention improves the tensile strength, flexural strength, and notched impact strength of the nylon matrix. In summary, the flame-retardant nylon material prepared by this invention possesses both excellent flame retardant and mechanical properties, achieving a synergistic improvement in both flame retardancy and mechanical properties.

[0030] The above content is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the scope defined by the inventive concept, they should all fall within the protection scope of the present invention.

Claims

1. A flame-retardant nylon material for protective face shields, characterized in that, The raw materials include the following parts by weight: 50-65 parts nylon 66 resin, 5-15 parts montmorillonite, 3-7 parts Zr-MOF-PS, 4-8 parts modified toughening agent, 0.1-0.5 parts antioxidant, 0.1-0.4 parts light stabilizer, 0.2-0.5 parts heat stabilizer, 0.2-0.6 parts bis-stearamide, and 0.3-0.8 parts isopropyltriethoxysilane; The Zr-MOF-PS is prepared by the following steps: Step A1: Mix bisphenol S and DMF, add aluminum trichloride, stir at room temperature for 30 min, then add phenyl phosphorus dichloride dropwise over 1 h. After the addition is complete, heat to 60 °C, react for 4 h, and then evaporate by rotary evaporation to obtain intermediate product 1. Step A2: Mix intermediate product 1 and DMF, heat to 50°C in an oil bath, stir, add p-aminobenzoic acid, heat to 80°C, react for 4 hours, filter under reduced pressure, wash, and dry under vacuum to obtain intermediate product 2. Step A3: Mix zirconium tetrachloride, biphenyl dicarboxylic acid and DMF, add glacial acetic acid, and then transfer to a high-pressure reactor. Stir at room temperature for 30 min, then place the reactor in a 120°C oven and heat for 36 h. After the reactor cools to room temperature, take out the sample, wash and dry it to obtain intermediate product 3. Step A4: Mix intermediate product 3 with anhydrous ethanol, add intermediate product 2 solution, stir at 60℃ for 1 h, after the reaction is complete, centrifuge, wash and dry to obtain Zr-MOF-PS.

2. The flame-retardant nylon material for a protective face mask according to claim 1, characterized in that, In step A1, the ratio of bisphenol S, DMF, aluminum trichloride, and phenyl phosphorus dichloride is 0.1-0.3 mol: 100-250 mL: 0.005-0.015 mol: 0.22-0.66 mol.

3. The flame-retardant nylon material for a protective face mask according to claim 1, characterized in that, In step A2, the ratio of intermediate product 1, DMF, and p-aminobenzoic acid is 0.08-0.12 mol: 80-120 mL: 0.176-0.264 mol.

4. The flame-retardant nylon material for protective face shields according to claim 1, characterized in that, In step A3, the ratio of zirconium tetrachloride, biphenyl dicarboxylic acid, DMF, and glacial acetic acid is 1-2 mmol: 1-2 mmol: 100-200 mL: 7-14 mL.

5. The flame-retardant nylon material for a protective face mask according to claim 1, characterized in that, In step A4, the ratio of intermediate product 3, anhydrous ethanol, and intermediate product 2 solution is 1g:80-100mL:80-100mL. Intermediate product 2 solution is prepared by mixing intermediate product 2 and anhydrous ethanol at a ratio of 0.4-0.5mmol:80-100mL.

6. The flame-retardant nylon material for a protective face mask according to claim 1, characterized in that, The modified toughening agent is prepared by the following steps: Step B1: Mix m-phenylenediamine, sebacic acid, 2,5-furandicarboxylic acid, deionized water and antioxidant 1098 and add them to the polymerization reactor. Seal the reactor, introduce nitrogen gas, raise the temperature to 150°C, stir and react for 30 min, then raise the temperature to 200°C and react for 2 h. Release the pressure of the reactor to atmospheric pressure, take out the product, and vacuum dry it to obtain carboxyl-terminated polyamide. Step B2: Mix 2,3-epoxypropyltrimethylammonium chloride, carboxyl-terminated polyamide and DMF, purge with nitrogen, heat to 70°C using an oil bath, react for 20 hours, rotary evaporate, and vacuum dry to obtain the modified toughening agent.

7. The flame-retardant nylon material for a protective face mask according to claim 6, characterized in that, In step B1, the ratio of intermediate phenylenediamine, sebacic acid, 2,5-furandicarboxylic acid, deionized water, and antioxidant 1098 is 0.1-0.2 mol: 0.1-0.2 mol: 0.1-0.2 mol: 4.5-9 g: 0.009-0.018 g.

8. The flame-retardant nylon material for a protective face mask according to claim 6, characterized in that, In step B2, the ratio of 2,3-epoxypropyltrimethylammonium chloride, carboxyl-terminated polyamide, and DMF is 0.16-0.2 mol: 0.08-0.1 mol: 50-70 mL.

9. The flame-retardant nylon material for a protective face mask according to claim 1, characterized in that, The antioxidant is at least one of antioxidant 1098 and antioxidant 168, the light stabilizer is at least one of UV234, UV360 and TFB117, and the heat stabilizer is at least one of calcium stearate, heat stabilizer H3336 and heat stabilizer S-EED.

10. A method for preparing a flame-retardant nylon material for a protective face mask according to any one of claims 1-9, characterized in that, The flame-retardant nylon material is prepared by the following steps: Step S1: Weigh the raw materials according to the weight parts, and thoroughly mix the nylon 66 resin, montmorillonite, Zr-MOF-PS, modified toughening agent, antioxidant, light stabilizer, heat stabilizer, bis-stearamide and isopropyltriethoxysilane to obtain a mixture. Step S2: Add the mixture to a twin-screw extruder, and after melting, extrusion, granulation, and drying, obtain the flame-retardant nylon material for protective face masks. The processing temperatures of each zone of the twin-screw extruder are as follows: Zone 1 180-190℃, Zone 2 190-200℃, Zone 3 210-220℃, Zone 4 220-230℃, Zone 5 220-230℃, Zone 6 220-230℃, Zone 7 220-230℃, Zone 8 220-230℃, and the die zone 220-230℃. The screw speed is 150-300 r / min.

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