A functional polyurethane coated nylon fabric and a method of making the same

Abstract

The application relates to the technical field of nylon fabric, and discloses a functional polyurethane-coated nylon fabric and a preparation method thereof. The functional polyurethane-coated nylon fabric is obtained by coating a polyurethane coating liquid on the surface of a nylon fabric; the polyurethane coating liquid is obtained by mixing antistatic flame retardant, polypropylene glycol, polyether modified silicone oil dispersant, ethyl acetate, silane modified nano silicon dioxide and polyurethane prepolymer; the polyurethane prepolymer is prepared from polypropylene glycol, toluene diisocyanate and a catalyst dibutyltin dilaurate; the silane modified nano silicon dioxide is prepared from nano silicon dioxide, an ethanol aqueous solution and a 3-aminopropyl triethoxysilane ethanol solution; and the antistatic flame retardant is prepared from diethanolamine, a formaldehyde aqueous solution, diethyl phosphite, anhydrous potassium carbonate and anhydrous dimethyl carbonate. The nylon fabric has good flame-retardant, antistatic and wear-resistant properties.

Description

Technical Field

[0001] This invention relates to the field of nylon fabric technology, specifically to a functional polyurethane-coated nylon fabric and its preparation method. Background Technology

[0002] Nylon fabrics are widely used in industrial textiles such as outdoor sportswear, parachutes, bags, and tents due to their high strength, high elasticity, and excellent abrasion resistance. However, as a typical flammable polymer material, nylon burns rapidly upon contact with a fire source, which limits its application in certain situations with high safety requirements.

[0003] Patent CN103031711A discloses a method for manufacturing flame-retardant nylon fabric, including the following steps: placing 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and methylene succinic acid into a three-necked flask containing organic solvent, heating and refluxing for 15-17 hours, the reaction being carried out under an inert gas atmosphere; after the reaction, filtering and washing to obtain a phosphorus-containing flame retardant; spraying the solid phosphorus-containing flame retardant onto the nylon fabric using a vacuum magnetron sputtering instrument for 20-30 minutes, and then drying the nylon fabric at a low temperature to obtain the flame-retardant nylon fabric. However, the existing technology still has some shortcomings: nylon fabric has poor moisture absorption and is prone to generating and accumulating static electricity due to friction. Static electricity accumulation not only causes the fabric to attract dust and cause discomfort when worn, but may also cause electric sparks or equipment malfunctions in environments such as the electronics industry and mining, posing a safety hazard. In addition, when used as a fabric for outdoor equipment, the nylon surface needs to withstand frequent friction and scratches, and its abrasion resistance still has room for improvement to extend its service life. Summary of the Invention

[0004] The purpose of this invention is to provide a functional polyurethane-coated nylon fabric and its preparation method, so as to solve the problems existing in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A functional polyurethane-coated nylon fabric is obtained by coating a polyurethane coating liquid onto the surface of a nylon fabric. The polyurethane coating liquid is obtained by mixing an antistatic flame retardant, polypropylene glycol, polyether-modified silicone oil dispersant, ethyl acetate, silane-modified nano-silica, and a polyurethane prepolymer. The polyurethane prepolymer is prepared from polypropylene glycol, toluene diisocyanate, and the catalyst dibutyltin dilaurate. The silane-modified nano-silica is prepared from nano-silica, an aqueous ethanol solution, and a 3-aminopropyltriethoxysilane ethanol solution. The antistatic flame retardant is prepared from diethanolamine, an aqueous formaldehyde solution, diethyl phosphite, anhydrous potassium carbonate, and anhydrous dimethyl carbonate.

[0006] Furthermore, the mass ratio of diethanolamine, formaldehyde aqueous solution, diethyl phosphite, anhydrous potassium carbonate, and anhydrous dimethyl carbonate is 100:(75-80):(130-135):(1-2):(45-48).

[0007] Furthermore, the mass ratio of nano-silica, aqueous ethanol solution, and 3-aminopropyltriethoxysilane ethanol solution is 100:(500-600):(20-30).

[0008] Furthermore, the mass ratio of toluene diisocyanate, polypropylene glycol, and the catalyst dibutyltin dilaurate is 100:(240-260):(0.1-0.3).

[0009] Furthermore, the mass ratio of polyurethane prepolymer, antistatic flame retardant, polypropylene glycol, polyether-modified silicone oil dispersant, ethyl acetate and silane-modified nano-silica is 100:(20-30):(10-20):(0.5-1):(45-55):(5-10).

[0010] A method for preparing a functional polyurethane-coated nylon fabric includes the following steps: (1) Diethanolamine is added to a closed reaction vessel. Under the conditions of 50-60℃ and 100-200rpm stirring speed, formaldehyde aqueous solution is added dropwise over 20-40 minutes. After the addition is completed, stirring is continued for 30-40 minutes. Then, the intermediate is dehydrated by vacuum distillation under the conditions of 40-50℃ and 800-1200Pa to obtain an intermediate. Then, under the conditions of nitrogen protection, 45-55℃ and 100-200rpm stirring speed, diethyl phosphite is added dropwise over 30-50 minutes. After stirring is continued for 2-3 hours, anhydrous potassium carbonate and anhydrous dimethyl carbonate are added over 20-40 minutes. After stirring is continued for 1-2 hours, an antistatic flame retardant is obtained. (2) Add nano-silica with a particle size of 10-20 nm to an ethanol aqueous solution with a mass fraction of 70-80%. Stir at a speed of 200-300 rpm for 30-40 minutes under ultrasonic assistance with a power of 300-400 W. Then add 3-aminopropyltriethoxysilane ethanol solution dropwise over 30-50 minutes. After the addition is complete, reflux and stir at 60-70 °C for 3-4 hours. After cooling to 20-25 °C, centrifuge to obtain a solid product. Wash the product and then vacuum dry at 70-80 °C for 6-8 hours to obtain silane-modified nano-silica. (3) Place polypropylene glycol in a sealed reactor and dehydrate it for 1-2 hours at a temperature of 80-90℃ and a vacuum of 800-1000Pa. Then, under nitrogen protection, at a temperature of 60-70℃ and a stirring speed of 150-250rpm, add toluene diisocyanate dropwise over 40-60 minutes. After the addition is complete, add the catalyst dibutyltin dilaurate and continue stirring for 2-3 hours to obtain polyurethane prepolymer. (4) Mix the antistatic flame retardant, polypropylene glycol, polyether-modified silicone oil dispersant and ethyl acetate, and stir at 500-1000 rpm for 10-15 minutes at 20-25℃. Then add silane-modified nano-silica and stir at 2000-3000 rpm for 30-40 minutes to obtain component B. Use polyurethane prepolymer as component A. Add component B to component A within 10-20 minutes before use, and then mix at 300-500 rpm for 10-15 minutes at 20-25℃ to obtain polyurethane coating liquid. (5) The polyurethane coating liquid is applied to the surface of the nylon fabric and then cured at 100-130°C for 8-15 minutes to obtain a functional polyurethane-coated nylon fabric.

[0011] Furthermore, the mass fraction of the formaldehyde aqueous solution in step (1) is 35-40%.

[0012] Furthermore, in step (2), the mass fraction of the 3-aminopropyltriethoxysilane ethanol solution is 10-15%.

[0013] Furthermore, the washing process in step (2) specifically involves washing 2-4 times with anhydrous ethanol.

[0014] Furthermore, in step (5), the wet coating amount is controlled to be 50-70 g / m².

[0015] Compared with the prior art, the beneficial effects achieved by the present invention are: 1. In this invention, the secondary amine group in the diethanolamine molecule undergoes a nucleophilic addition reaction with the carbonyl group in the formaldehyde molecule to generate a hydroxymethyl intermediate. This intermediate further undergoes a nucleophilic substitution reaction with the phosphorus atom in the diethyl phosphite molecule, introducing phosphorus and hydroxyl groups. The phosphorus can promote the formation of a char layer during thermal decomposition. Subsequently, the tertiary amine nitrogen atom in this intermediate undergoes a quaternization reaction with dimethyl carbonate to generate a quaternary ammonium salt structure. The silanols on the surface of nano-silica undergo a condensation reaction with the silanol generated by the hydrolysis of 3-aminopropyltriethoxysilane to form a covalently linked organic modified layer, resulting in silane-modified nano-silica, thereby improving the dispersion uniformity of nano-silica. The hydroxyl groups at the ends of the polypropylene glycol chain undergo stepwise addition polymerization with the isocyanate groups in the toluene diisocyanate molecule under the action of the catalyst dibutyltin dilaurate to generate a polyurethane prepolymer containing isocyanate groups. The hydroxyl groups of the antistatic flame retardant... The hydroxyl groups of the antistatic flame retardant react with the isocyanate groups in the polyurethane prepolymer molecule to form urethane bonds, thus chemically bonding the antistatic flame retardant to the polyurethane network. The subsequently added polypropylene glycol acts as a chain extender; its hydroxyl groups react with the isocyanate groups of the polyurethane prepolymer to extend the polyurethane chain structure. The amino groups of the silane-modified nano-silica react with the isocyanate groups of the polyurethane prepolymer to form urea bonds, thus bonding the nano-silica to the polyurethane network. The phosphorus and nitrogen elements of the antistatic flame retardant work synergistically during combustion; phosphorus promotes char formation to isolate oxygen and heat, while nitrogen releases inert gases to dilute combustible gases, thereby achieving a flame-retardant effect. Quaternary ammonium salt groups adsorb moisture from the air through their hydrophilicity, forming a water film on the fabric surface and dissipating static charge through ion conduction, reducing static accumulation and achieving antistatic properties. The high hardness of the nano-silica enhances the fabric's abrasion resistance. Detailed Implementation

[0016] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0017] A functional polyurethane-coated nylon fabric is obtained by coating a polyurethane coating liquid onto the surface of a nylon fabric. The polyurethane coating liquid is obtained by mixing an antistatic flame retardant, polypropylene glycol, polyether-modified silicone oil dispersant, ethyl acetate, silane-modified nano-silica, and a polyurethane prepolymer. The polyurethane prepolymer is prepared from polypropylene glycol, toluene diisocyanate, and the catalyst dibutyltin dilaurate. The silane-modified nano-silica is prepared from nano-silica, an aqueous ethanol solution, and a 3-aminopropyltriethoxysilane ethanol solution. The antistatic flame retardant is prepared from diethanolamine, an aqueous formaldehyde solution, diethyl phosphite, anhydrous potassium carbonate, and anhydrous dimethyl carbonate.

[0018] For experiments not specifically described in the examples, the procedures and conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products. The number average molecular weight of polypropylene glycol is 1000 g / mol.

[0019] Example 1

[0020] (1) Diethanolamine was added to a closed reaction vessel. Under the conditions of 50°C and 100 rpm stirring speed, a 35% formaldehyde aqueous solution was added dropwise over 20 minutes. After the addition was completed, stirring was continued for 30 minutes. Then, the intermediate was dehydrated by vacuum distillation under the conditions of 40°C and 800 Pa. Then, under the conditions of nitrogen protection, 45°C and 100 rpm stirring speed, diethyl phosphite was added dropwise over 30 minutes. After stirring was continued for 2 hours, anhydrous potassium carbonate and anhydrous dimethyl carbonate were added over 20 minutes. After stirring was continued for 1 hour, an antistatic flame retardant was obtained. The mass ratio of diethanolamine, formaldehyde aqueous solution, diethyl phosphite, anhydrous potassium carbonate and anhydrous dimethyl carbonate was 100:75:130:1:45.

[0021] (2) 10 nm nano-silica was added to a 70% ethanol aqueous solution. The mixture was stirred at 200 rpm for 30 minutes with ultrasonic assistance at 300 W. Then, a 10% 3-aminopropyltriethoxysilane ethanol solution was added dropwise over 30 minutes. After the addition was complete, the mixture was refluxed and stirred at 60 °C for 3 hours. After cooling to 20 °C, the solid product was obtained by centrifugation and washed twice with anhydrous ethanol. The solid product was then vacuum dried at 70 °C for 6 hours to obtain silane-modified nano-silica. The mass ratio of nano-silica, ethanol aqueous solution and 3-aminopropyltriethoxysilane ethanol solution was 100:500:20.

[0022] (3) Polypropylene glycol was placed in a sealed reactor and dehydrated for 1 hour at a temperature of 80°C and a vacuum of 800Pa. Then, under nitrogen protection, at a temperature of 60°C and a stirring speed of 150rpm, toluene diisocyanate was added dropwise over 40 minutes. After the addition was complete, dibutyltin dilaurate catalyst was added and stirring was continued for 2 hours to obtain polyurethane prepolymer. The mass ratio of toluene diisocyanate, polypropylene glycol and dibutyltin dilaurate catalyst was 100:240:0.1.

[0023] (4) Mix the antistatic flame retardant, polypropylene glycol, polyether-modified silicone oil dispersant and ethyl acetate, stir at 500 rpm for 10 minutes at 20°C, then add silane-modified nano-silica and stir at 2000 rpm for 30 minutes to obtain component B; take the polyurethane prepolymer as component A, add component B to component A within 10 minutes before use, and then mix at 300 rpm for 10 minutes at 20°C to obtain polyurethane coating liquid; wherein the mass ratio of polyurethane prepolymer, antistatic flame retardant, polypropylene glycol, polyether-modified silicone oil dispersant, ethyl acetate and silane-modified nano-silica is 100:20:10:0.5:45:5.

[0024] (5) The polyurethane coating liquid is applied to the surface of a nylon fabric with a weight of 150 g / m², and the wet coating amount is controlled to be 50 g / m². Then, it is cured at 100°C for 8 minutes to obtain a functional polyurethane-coated nylon fabric.

[0025] Example 2

[0026] (1) Diethanolamine was added to a closed reaction vessel. Under the conditions of 55°C and 150 rpm stirring speed, a 37.5% formaldehyde aqueous solution was added dropwise over 30 minutes. After the addition was completed, stirring was continued for 35 minutes. Then, the intermediate was dehydrated by vacuum distillation under the conditions of 45°C and 1000 Pa. Then, under the conditions of nitrogen protection, 50°C and 150 rpm stirring speed, diethyl phosphite was added dropwise over 40 minutes. After stirring was continued for 2.5 hours, anhydrous potassium carbonate and anhydrous dimethyl carbonate were added over 30 minutes. After stirring was continued for 1.5 hours, an antistatic flame retardant was obtained. The mass ratio of diethanolamine, formaldehyde aqueous solution, diethyl phosphite, anhydrous potassium carbonate and anhydrous dimethyl carbonate was 100:77.5:132.5:1.5:46.5.

[0027] (2) 15 nm nano-silica was added to a 75% ethanol aqueous solution. The mixture was stirred at 250 rpm for 35 minutes with ultrasonic assistance at 350 W. Then, a 12.5% ​​3-aminopropyltriethoxysilane ethanol solution was added dropwise over 40 minutes. After the addition was complete, the mixture was refluxed and stirred at 65 °C for 3.5 hours. After cooling to 22 °C, the solid product was obtained by centrifugation and washed three times with anhydrous ethanol. The solid product was then vacuum dried at 75 °C for 7 hours to obtain silane-modified nano-silica. The mass ratio of nano-silica, ethanol aqueous solution and 3-aminopropyltriethoxysilane ethanol solution was 100:550:25.

[0028] (3) Polypropylene glycol was placed in a sealed reactor and dehydrated for 1.5 hours at a temperature of 85°C and a vacuum of 900 Pa. Then, under nitrogen protection, at a temperature of 65°C and a stirring speed of 200 rpm, toluene diisocyanate was added dropwise over 50 minutes. After the addition was complete, dibutyltin dilaurate catalyst was added and stirring was continued for 2.5 hours to obtain polyurethane prepolymer. The mass ratio of toluene diisocyanate, polypropylene glycol and dibutyltin dilaurate catalyst was 100:250:0.2.

[0029] (4) Mix the antistatic flame retardant, polypropylene glycol, polyether-modified silicone oil dispersant and ethyl acetate, stir at 750 rpm for 12.5 minutes at 22°C, then add silane-modified nano-silica and stir at 2500 rpm for 35 minutes to obtain component B; take the polyurethane prepolymer as component A, add component B to component A within 15 minutes before use, and then mix at 400 rpm for 12.5 minutes at 22°C to obtain polyurethane coating liquid; wherein the mass ratio of polyurethane prepolymer, antistatic flame retardant, polypropylene glycol, polyether-modified silicone oil dispersant, ethyl acetate and silane-modified nano-silica is 100:25:15:0.75:50:7.5.

[0030] (5) The polyurethane coating liquid is applied to the surface of a nylon fabric with a basis weight of 150 g / m², and the wet coating amount is controlled to be 60 g / m². Then, it is cured at 115°C for 11.5 minutes to obtain a functional polyurethane-coated nylon fabric.

[0031] Example 3

[0032] (1) Diethanolamine was added to a closed reaction vessel. Under the conditions of 60°C and 200 rpm stirring speed, a 40% formaldehyde aqueous solution was added dropwise over 40 minutes. After the addition was completed, stirring was continued for 40 minutes. Then, the intermediate was dehydrated by vacuum distillation under the conditions of 50°C and 1200 Pa. Then, under the conditions of nitrogen protection, 55°C and 200 rpm stirring speed, diethyl phosphite was added dropwise over 50 minutes. After stirring was continued for 3 hours, anhydrous potassium carbonate and anhydrous dimethyl carbonate were added over 40 minutes. After stirring was continued for 2 hours, an antistatic flame retardant was obtained. The mass ratio of diethanolamine, formaldehyde aqueous solution, diethyl phosphite, anhydrous potassium carbonate and anhydrous dimethyl carbonate was 100:80:135:2:48.

[0033] (2) 20 nm nano-silica was added to an 80% ethanol aqueous solution. The mixture was stirred at 300 rpm for 40 minutes with ultrasonic assistance at 400 W. Then, a 15% 3-aminopropyltriethoxysilane ethanol solution was added dropwise over 50 minutes. After the addition was complete, the mixture was refluxed and stirred at 70 °C for 4 hours. After cooling to 25 °C, the solid product was obtained by centrifugation and washed four times with anhydrous ethanol. The solid product was then vacuum dried at 80 °C for 8 hours to obtain silane-modified nano-silica. The mass ratio of nano-silica, ethanol aqueous solution and 3-aminopropyltriethoxysilane ethanol solution was 100:600:30.

[0034] (3) Polypropylene glycol was placed in a sealed reactor and dehydrated for 2 hours at a temperature of 90°C and a vacuum of 1000Pa. Then, under nitrogen protection, at a temperature of 70°C and a stirring speed of 250rpm, toluene diisocyanate was added dropwise over 60 minutes. After the addition was complete, dibutyltin dilaurate catalyst was added and stirring was continued for 3 hours to obtain polyurethane prepolymer. The mass ratio of toluene diisocyanate, polypropylene glycol and dibutyltin dilaurate catalyst was 100:260:0.3.

[0035] (4) Mix the antistatic flame retardant, polypropylene glycol, polyether-modified silicone oil dispersant and ethyl acetate, stir at 1000 rpm for 15 minutes at 25°C, then add silane-modified nano-silica and stir at 3000 rpm for 40 minutes to obtain component B; take the polyurethane prepolymer as component A, add component B to component A within 20 minutes before use, and then mix at 500 rpm for 15 minutes at 25°C to obtain polyurethane coating liquid; wherein the mass ratio of polyurethane prepolymer, antistatic flame retardant, polypropylene glycol, polyether-modified silicone oil dispersant, ethyl acetate and silane-modified nano-silica is 100:30:20:1:55:10.

[0036] (5) The polyurethane coating liquid is applied to the surface of a nylon fabric with a basis weight of 150 g / m², and the wet coating amount is controlled to be 70 g / m². Then, it is cured at 130°C for 15 minutes to obtain a functional polyurethane-coated nylon fabric.

[0037] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that the addition of the antistatic flame retardant is omitted.

[0038] Comparative Example 2 The only difference between Comparative Example 2 and Example 1 is that the addition of silane-modified nano-silica is omitted.

[0039] The flame retardant performance was tested according to GB / T5455-2014, the antistatic performance according to GB / T12703.2-2021, and the abrasion resistance according to GB / T21196.2-2007. Table 1 below shows the performance analysis results of the embodiments and comparative examples of the present invention.

[0040] Table 1

[0041] Experimental data from the examples and comparative examples show that the present invention uses an antistatic flame retardant as a multifunctional additive and nano-silica as a wear-resistant reinforcing agent. The phosphorus and nitrogen elements in the antistatic flame retardant work synergistically during combustion. The phosphorus element promotes the formation of a char layer to isolate oxygen and heat, while the nitrogen element releases inert gas to dilute combustible gas, thereby inhibiting combustion. At the same time, the quaternary ammonium salt groups adsorb moisture in the air through their own hydrophilicity, forming a water film on the fabric surface, and dissipate static charge through ion conduction mechanism to reduce static accumulation. The nano-silica enhances the wear resistance of the fabric surface through its high hardness. Thus, the nylon fabric has good flame retardant, antistatic and wear-resistant properties.

[0042] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.

Claims

1. A functional polyurethane-coated nylon fabric, characterized in that, Functional polyurethane-coated nylon fabric is obtained by coating the surface of nylon fabric with a polyurethane coating liquid; the polyurethane coating liquid is obtained by mixing an antistatic flame retardant, polypropylene glycol, polyether-modified silicone oil dispersant, ethyl acetate, silane-modified nano-silica, and polyurethane prepolymer; the polyurethane prepolymer is prepared by polypropylene glycol, toluene diisocyanate, and the catalyst dibutyltin dilaurate; the silane-modified nano-silica is prepared by nano-silica, an aqueous ethanol solution, and a 3-aminopropyltriethoxysilane ethanol solution; the antistatic flame retardant is prepared by diethanolamine, an aqueous formaldehyde solution, diethyl phosphite, anhydrous potassium carbonate, and anhydrous dimethyl carbonate.

2. The functional polyurethane-coated nylon fabric according to claim 1, characterized in that: The mass ratio of diethanolamine, formaldehyde aqueous solution, diethyl phosphite, anhydrous potassium carbonate, and anhydrous dimethyl carbonate is 100:(75-80):(130-135):(1-2):(45-48).

3. The functional polyurethane-coated nylon fabric according to claim 1, characterized in that: The mass ratio of nano-silica, aqueous ethanol solution and 3-aminopropyltriethoxysilane ethanol solution is 100:(500-600):(20-30).

4. The functional polyurethane-coated nylon fabric according to claim 1, characterized in that: The mass ratio of toluene diisocyanate, polypropylene glycol, and catalyst dibutyltin dilaurate is 100:(240-260):(0.1-0.3).

5. The functional polyurethane-coated nylon fabric according to claim 1, characterized in that: The mass ratio of polyurethane prepolymer, antistatic flame retardant, polypropylene glycol, polyether-modified silicone oil dispersant, ethyl acetate and silane-modified nano silica is 100:(20-30):(10-20):(0.5-1):(45-55):(5-10).

6. A method for preparing a functional polyurethane-coated nylon fabric, applied to the functional polyurethane-coated nylon fabric according to any one of claims 1-5, characterized in that, Includes the following steps: (1) Diethanolamine is added to a closed reaction vessel. Under the conditions of 50-60℃ and 100-200rpm stirring speed, formaldehyde aqueous solution is added dropwise over 20-40 minutes. After the addition is completed, stirring is continued for 30-40 minutes. Then, the intermediate is dehydrated by vacuum distillation under the conditions of 40-50℃ and 800-1200Pa to obtain an intermediate. Then, under the conditions of nitrogen protection, 45-55℃ and 100-200rpm stirring speed, diethyl phosphite is added dropwise over 30-50 minutes. After stirring is continued for 2-3 hours, anhydrous potassium carbonate and anhydrous dimethyl carbonate are added over 20-40 minutes. After stirring is continued for 1-2 hours, an antistatic flame retardant is obtained. (2) Add nano-silica with a particle size of 10-20 nm to an ethanol aqueous solution with a mass fraction of 70-80%. Stir at a speed of 200-300 rpm for 30-40 minutes under ultrasonic assistance with a power of 300-400 W. Then add 3-aminopropyltriethoxysilane ethanol solution dropwise over 30-50 minutes. After the addition is complete, reflux and stir at 60-70 °C for 3-4 hours. After cooling to 20-25 °C, centrifuge to obtain a solid product. Wash the product and then vacuum dry at 70-80 °C for 6-8 hours to obtain silane-modified nano-silica. (3) Place polypropylene glycol in a sealed reactor and dehydrate it for 1-2 hours at a temperature of 80-90℃ and a vacuum of 800-1000Pa. Then, under nitrogen protection, at a temperature of 60-70℃ and a stirring speed of 150-250rpm, add toluene diisocyanate dropwise over 40-60 minutes. After the addition is complete, add the catalyst dibutyltin dilaurate and continue stirring for 2-3 hours to obtain polyurethane prepolymer. (4) Mix the antistatic flame retardant, polypropylene glycol, polyether-modified silicone oil dispersant and ethyl acetate, and stir at 500-1000 rpm for 10-15 minutes at 20-25℃. Then add silane-modified nano-silica and stir at 2000-3000 rpm for 30-40 minutes to obtain component B. Use polyurethane prepolymer as component A. Add component B to component A within 10-20 minutes before use, and then mix at 300-500 rpm for 10-15 minutes at 20-25℃ to obtain polyurethane coating liquid. (5) The polyurethane coating liquid is applied to the surface of the nylon fabric and then cured at 100-130°C for 8-15 minutes to obtain a functional polyurethane-coated nylon fabric.

7. The method for preparing a functional polyurethane-coated nylon fabric according to claim 6, characterized in that: The mass fraction of the formaldehyde aqueous solution in step (1) is 35-40%.

8. The method for preparing a functional polyurethane-coated nylon fabric according to claim 6, characterized in that: In step (2), the mass fraction of the 3-aminopropyltriethoxysilane ethanol solution is 10-15%.

9. The method for preparing a functional polyurethane-coated nylon fabric according to claim 6, characterized in that: The washing process in step (2) specifically involves washing with anhydrous ethanol 2-4 times.

10. The method for preparing a functional polyurethane-coated nylon fabric according to claim 6, characterized in that: In step (5), the wet coating amount is controlled to be 50-70 g / m².

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