Polymer composite material containing nanofiber and preparation method thereof

Abstract

The invention discloses a nanofiber-containing polymer composite material and a preparation method thereof, and the nanofiber-containing polymer composite material is prepared from the following raw materials in parts by weight: 90-100 parts of polypropylene, 10-15 parts of nylon 6, 13-16 parts of a modified flame retardant, 4-7 parts of modified carbon nanotubes, 3-5 parts of a compatilizer, 0.5-0.8 part of an antioxidant and 0.3-0.5 part of a lubricant. According to the composite material, polypropylene and nylon 6 are blended, and a modified flame retardant prepared by a formulated method, a modified carbon nanotube, a synergistic compatilizer and other assistants are added, so that the defects that an existing polypropylene material is easy to degrade and inflammable, a traditional flame retardant and an antioxidant are easy to migrate and lose efficacy and the like are effectively overcome; according to the polypropylene composite material, the mechanical property of the material is maintained and improved while efficient flame retardance and excellent weather resistance and aging resistance (especially ultraviolet aging resistance) are achieved, the problem that in the prior art, performance in multiple aspects is difficult to consider is solved, and the application range of the polypropylene composite material is widened.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and particularly relates to a polymer composite material containing nanofibers and a preparation method thereof. Background Art

[0002] With the development of science and technology and the improvement of people's living standards, people's demand for various materials has gradually increased, and various plastic products have gradually come into people's view. Plastic is a polymer compound made of monomers through addition or condensation reactions. It is mainly composed of synthetic resins and various additives. Among many polymer materials, polypropylene has become one of the preferred materials in plastic production due to its good chemical stability, low density, good electrical insulation, odorlessness and non-toxicity. It is widely used in home appliances, packaging, medical care, automobiles and other fields.

[0003] However, the presence of tertiary carbon-hydrogen bonds in its molecular structure makes it susceptible to free radical reactions under the influence of ultraviolet light, oxygen, and heat, leading to molecular chain breakage and oxidative degradation. This degradation is directly manifested as a decrease in the material's tensile strength and elongation at break. Furthermore, polypropylene is a flammable material and will quickly ignite when exposed to open flames or high temperatures, making it prone to fire and posing a significant safety hazard. Furthermore, the combustion process of polypropylene produces large amounts of heat, smoke, and toxic gases, which not only threaten human life and property safety but also have a serious impact on the environment. Therefore, polypropylene plastic still has certain shortcomings in practical applications.

[0004] To improve flame retardancy, DOPO-based flame retardants are currently used. However, their molecular structure results in low flame retardancy. Furthermore, DOPO-based flame retardants have poor compatibility with non-polar polymers like polyolefins, easily agglomerating and migrating to the material surface, further reducing flame retardancy. They also affect the interfacial properties with the polymer matrix, accelerating material aging, leading to performance degradation and shortened lifespan. Antioxidant technology for polypropylene aging also has shortcomings. These antioxidants are prone to volatilization and loss during high-temperature processing, resulting in suboptimal long-term anti-aging effects. Due to their poor compatibility with polymers, they are prone to migration and precipitation, affecting the material's appearance and long-term stability.

[0005] Chinese patent application CN110903548A discloses a polypropylene-glass fiber composite material. The composite material is composed of a polypropylene masterbatch, glass fiber, polypropylene fiber, a coupling agent, and maleic anhydride-grafted polypropylene. The weight percentages are: 40%-42% polypropylene masterbatch, 36%-38% glass fiber, 10%-12% polypropylene fiber, 2%-4% coupling agent, and 6%-10% maleic anhydride-grafted polypropylene. The polypropylene masterbatch comprises T30S and EPS30R in a 1:1 weight ratio. The polypropylene-glass fiber composite material is produced by twin-screw coextrusion. This invention improves the mechanical properties and heat resistance of the polypropylene-glass fiber composite material, achieving a modulus comparable to that of wooden formwork. The resulting product is less prone to deformation and bending, and reduces production costs. However, this patent fails to significantly improve the flame retardancy and UV aging resistance of the polypropylene material. Chinese patent application CN118421011A discloses a fiber-reinforced flame-retardant polypropylene composite material, its preparation method, and its application. The fiber-reinforced flame-retardant polypropylene composite material comprises the following components by weight: 4-30 parts polypropylene, 10-30 parts flame retardant, 3-10 parts flame retardant synergist, 5-20 parts modifier, 3-8 parts compatibilizer, and 35-50 parts glass fiber. This invention, by introducing a modifier as a component into the material and compounding specific polypropylene, flame retardant, flame retardant synergist, and compatibilizer, can improve the impregnation effect of the glass fiber, avoid obvious appearance defects in the material, and prevent the material from decreasing in flame retardant efficiency. It can also effectively improve the interlaminar shear strength after the material is laid, thereby giving the composite material the advantages of light weight, high strength, good appearance, high flame retardant efficiency, and good mechanical properties. However, this patent does not improve the UV aging resistance of polypropylene.

[0006] Therefore, how to achieve high-efficiency flame retardancy and excellent aging resistance while maintaining or improving the original excellent mechanical properties of polymer composites as much as possible and avoiding the negative impact caused by the addition of additives is a key issue that needs to be urgently addressed in the current field of polymer material modification. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the present invention aims to provide a polymer composite material containing nanofibers and a preparation method thereof.

[0008] To achieve the above object, the present invention provides the following technical solutions: A polymer composite material containing nanofibers, comprising the following raw materials in parts by weight: 90-100 parts of polypropylene, 10-15 parts of nylon 6, 13-16 parts of modified flame retardant, 4-7 parts of modified carbon nanotubes, 3-5 parts of compatibilizer, 0.5-0.8 parts of antioxidant, and 0.3-0.5 parts of lubricant.

[0009] Preferably, a polymer composite material containing nanofibers comprises the following raw materials, by weight: 95-100 parts of polypropylene, 10-13 parts of nylon 6, 13-18 parts of modified flame retardant, 4-6 parts of modified carbon nanotubes, 3-4 parts of compatibilizer, 0.5-0.7 parts of antioxidant, and 0.4-0.5 parts of lubricant.

[0010] In the present invention, polypropylene and nylon are used as the base materials, modified flame retardants and modified carbon nanotubes prepared by a specific method are added, and compatibilizers, antioxidants and lubricants are added. This allows the composite material to maintain good processing performance while comprehensively improving flame retardancy, mechanical properties, and weather and aging resistance.

[0011] Preferably, the preparation method of the modified flame retardant is as follows: S1, adding ammonium polyphosphate to anhydrous ethanol, then adding sodium lauryl sulfate, stirring evenly to obtain an ammonium polyphosphate suspension; then adding titanium dioxide sol dropwise to the ammonium polyphosphate suspension under stirring, stirring and reacting after the addition is completed, aging after the reaction is completed, then filtering, washing, and drying to obtain composite ammonium polyphosphate; S2, adding the composite ammonium polyphosphate prepared in step S1 to an ethanol aqueous solution, then adding γ-glycidyloxypropyltrimethoxysilane, and reacting at a constant temperature. After the reaction is completed, filtering, washing, and drying to obtain silane-modified ammonium polyphosphate; S3. Add butanone to the silane-modified ammonium polyphosphate in step S2, and then add 2,2,6,6-tetramethyl-4-piperidinol and triethylamine to carry out a ring-opening reaction. After the reaction is completed, filter, wash, and dry to obtain a modified flame retardant.

[0012] Preferably, the mass ratio of ammonium polyphosphate, sodium lauryl sulfate, and anhydrous ethanol in step S1 is 80-90:2-3:1000, the mass ratio of the ammonium polyphosphate suspension and the titanium dioxide sol is 1000:200-300, the stirring reaction temperature is 30-40°C, the time is 2-4h, the aging temperature is 20-25°C, and the time is 12-16h; the preparation method of the titanium dioxide sol is as follows: 15-20g of tetrabutyl titanate is added to 200-300g of anhydrous ethanol, followed by dropwise addition of 1.5-2g of deionized water, and stirring at 500-800r / min for 1-2h.

[0013] In the present invention, sodium dodecyl sulfate is used as a dispersant, and titanium dioxide sol is uniformly coated on the surface of ammonium polyphosphate in an anhydrous ethanol medium to form a composite ammonium polyphosphate with a core-shell structure. This not only utilizes the ultraviolet shielding and potential flame retardant synergistic effects of TiO2 to protect the ammonium polyphosphate, but also provides abundant hydroxyl active sites on its surface.

[0014] Preferably, in step S2, the mass ratio of the composite ammonium polyphosphate to γ-glycidyloxypropyltrimethoxysilane is 90-100:8-11, the temperature of the isothermal reaction is 60-70° C., and the time is 2-3 h.

[0015] In the present invention, epoxy groups are successfully introduced by reacting γ-glycidyloxypropyltrimethoxysilane with the TiO2 layer on the surface of the composite ammonium polyphosphate, providing active sites for subsequent reactions.

[0016] Preferably, in step S3, the mass ratio of silane-modified ammonium polyphosphate, 2,2,6,6-tetramethyl-4-piperidinol, and triethylamine is 90-100:5.5-7.5:2-3, and the temperature of the ring-opening reaction is 60-70° C., and the time is 3-4 hours.

[0017] In this invention, a ring-opening reaction between epoxy groups and the alcoholic hydroxyl groups of 2,2,6,6-tetramethyl-4-piperidinol allows the 2,2,6,6-tetramethyl-4-piperidinol to be covalently bonded to the surface of the flame retardant particles. This effectively prevents its migration and volatilization loss within the polymer matrix, ensuring the long-term effectiveness of the anti-aging effect. Application of this modified flame retardant in composite materials not only effectively utilizes the intumescent flame retardant properties of ammonium polyphosphate, but the introduction of TiO2 also enhances the flame retardant effect by promoting charring and insulating against heat and oxygen. Furthermore, the grafted 2,2,6,6-tetramethyl-4-piperidinol effectively captures free radicals generated by the degradation of the polymer under light and heat, significantly improving the weather resistance and service life of the composite material.

[0018] Preferably, the preparation method of the modified carbon nanotubes is as follows: The carbon nanotubes are added to concentrated nitric acid for immersion treatment to obtain pretreated carbon nanotubes after the treatment; the pretreated carbon nanotubes are then added to an ethanol aqueous solution, followed by the addition of γ-glycidyloxypropyltrimethoxysilane, and stirred for reaction. After the reaction is completed, the carbon nanotubes are filtered, washed, and dried to obtain epoxy carbon nanotubes; the epoxy carbon nanotubes are added to toluene, followed by the addition of 2-(2-hydroxy-5-benzyl)benzotriazole and triethylamine, and heated for reaction. After the reaction is completed, the carbon nanotubes are filtered, washed, and dried to obtain modified carbon nanotubes.

[0019] Preferably, the temperature of the immersion treatment is 40-50°C, and the time is 1-2h; the mass ratio of the pretreated carbon nanotubes and γ-glycidyloxypropyltrimethoxysilane is 50-60:4-7, the temperature of the stirring reaction is 60-70°C, and the time is 2-3h; the mass ratio of the epoxy carbon nanotubes, 2-(2-hydroxy-5-benzyl)benzotriazole, and triethylamine is 50-60:4-7:1-2, the temperature of the heating reaction is 70-80°C, and the time is 2-3h.

[0020] In the present invention, carbon nanotubes are impregnated with concentrated nitric acid to introduce oxygen-containing functional groups such as carboxyl and hydroxyl groups onto the surface of the carbon nanotubes. Subsequently, these oxygen-containing functional groups are reacted with γ-glycidyloxypropyltrimethoxysilane to covalently bond epoxy groups to the surface of the carbon nanotubes. Finally, the epoxy groups react with the phenolic hydroxyl groups of 2-(2-hydroxy-5-benzyl)benzotriazole to successfully graft 2-(2-hydroxy-5-benzyl)benzotriazole molecules onto the surface of the carbon nanotubes, thereby achieving dual functionalization of the carbon nanotube surface. 2-(2-hydroxy-5-benzyl)benzotriazole is fixed to carbon nanotubes through covalent bonds, avoiding its migration and precipitation, and improving the durability and efficiency of its ultraviolet absorption in the composite material; on the one hand, the modified carbon nanotubes can effectively enhance the tensile strength, flexural strength and other mechanical indicators of the composite material by virtue of their excellent mechanical properties; on the other hand, the grafted (2-hydroxy-5-benzyl)benzotriazole gives the carbon nanotubes excellent ultraviolet absorption ability, which can protect the polymer matrix from ultraviolet light degradation and further improve the weather resistance of the material.

[0021] The present invention also protects a method for preparing the above-mentioned polymer composite material containing nanofibers, comprising the following steps: The raw materials are weighed according to the formula, added into a high-speed mixer, mixed evenly, and then granulated by twin-screw extrusion to obtain the polymer composite material containing nanofibers.

[0022] Preferably, the mixing speed is 700-900 r / min, the mixing time is 5-10 min; and the extrusion temperature is 230-250°C.

[0023] Compared with the prior art, the present invention has the following beneficial effects: (1) The polymer composite material containing nanofibers provided by the present invention is prepared by blending polypropylene with nylon 6 and adding modified flame retardants and modified carbon nanotubes prepared by a specific method, synergistic compatibilizers and other auxiliary agents. The composite material effectively overcomes the defects of existing polypropylene materials such as easy degradation and flammability, and easy migration and failure of traditional flame retardants and antioxidants. While achieving high-efficiency flame retardancy and excellent weather and aging resistance (especially UV aging resistance), the mechanical properties of the material are maintained and improved, thus solving the problem that the existing technology is difficult to take into account multiple performance aspects and broadening the application range of polypropylene composite materials.

[0024] (2) The polymer composite material containing nanofibers provided by the present invention is added with a modified flame retardant, and ammonium polyphosphate is sequentially coated with titanium dioxide, γ-glycidyloxypropyltrimethoxysilane is introduced into an epoxy group, and the ammonium polyphosphate is subjected to a ring-opening reaction with 2,2,6,6-tetramethyl-4-piperidinol, and the tetramethylpiperidinol group is grafted and fixed, thereby giving the flame retardant multiple functions. This modification method not only improves the thermal stability of APP through the TiO2 layer and may produce a flame retardant synergistic effect, but more importantly, the 2,2,6,6-tetramethyl-4-piperidinol component is used as a flame retardant. The modified flame retardant is firmly anchored on the surface of the flame retardant particles in the form of covalent bonds, which effectively solves the problems of poor compatibility of traditional UV aging agents in polypropylene, easy volatilization loss during high-temperature processing, and easy migration and precipitation during long-term use, ensuring the long-term and stability of the anti-aging effect; at the same time, the modified flame retardant uses a specific preparation method to make ammonium polyphosphate have better flame retardant efficiency and compatibility with the polymer matrix, avoiding the performance degradation of the composite material and premature aging of the material due to the migration of the additive, and giving the composite material excellent flame retardancy and long-lasting aging resistance.

[0025] (3) The polymer composite material containing nanofibers provided by the present invention is prepared by pretreatment with concentrated nitric acid, grafting with epoxy groups, and ring-opening grafting and fixation with 2-(2-hydroxy-5-phenylmethyl)benzotriazole. This method allows 2-(2-hydroxy-5-phenylmethyl)benzotriazole to be stably grafted on the surface of the carbon nanotube in the form of a covalent bond, fundamentally solving the defects of traditional small molecule ultraviolet absorbers such as easy migration, easy volatility, and poor extraction resistance, and ensuring its long-lasting ultraviolet protection effect in the composite material. At the same time, the carbon nanotube itself is an excellent nanofiller, and its surface functionalization improves its dispersibility and interfacial compatibility in the polymer matrix, which can effectively exert its nano-enhancement effect and significantly improve the mechanical strength of the composite material. In addition, the introduction of modified carbon nanotubes not only strengthens the mechanical skeleton of the material, but also gives the material excellent and long-lasting ultraviolet aging resistance.

[0026] (4) The polymer composite material containing nanofibers provided by the present invention, the modified flame retardant and the modified carbon nanotubes can exert a significant synergistic enhancement effect in the polymer matrix; in terms of flame retardancy, the modified ammonium polyphosphate serves as the main intumescent flame retardant and forms an intumescent carbon layer during combustion, while the modified carbon nanotubes, due to their good thermal stability and network structure, can enhance the structural strength and density of the intumescent carbon layer, effectively prevent molten dripping, and further isolate the transfer of heat and combustible gas; in terms of weather resistance and anti-aging, the physical shielding of TiO2 on the surface of the modified flame retardant and the chemical free radical capture function of the 2,2,6,6-tetramethyl-4-piperidine group, combined with the ultraviolet absorption function of the benzotriazole group on the surface of the modified carbon nanotubes, can synergistically improve the anti-ultraviolet performance of the composite material, and the effect is far better than that of a single additive. The presence of the two modified filler surface functional groups can promote the uniform dispersion and interface compatibility of the filler in the matrix through interaction with the compatibilizer and the polymer matrix, thereby also having a positive effect on the mechanical properties of the composite material. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all 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.

[0028] Unless otherwise specified, the chemical reagents and materials in the present invention are purchased from commercial sources or synthesized from commercially purchased raw materials.

[0029] The brand of the polypropylene is Sinopec PPH-T03; the brand of the nylon 6 is Baling Petrochemical BL3280H; the carbon nanotubes are multi-walled carbon nanotubes with a diameter of 20-30 nm and a length of 5-10 μm; and the degree of polymerization of the ammonium polyphosphate is greater than 1000. Example 1

[0030] A polymer composite material containing nanofibers, comprising the following raw materials in parts by weight: 95 parts of polypropylene, 13 parts of nylon 6, 15 parts of modified flame retardant, 6 parts of modified carbon nanotubes, 4 parts of maleic anhydride grafted polypropylene, 0.7 parts of antioxidant 1010, and 0.4 parts of silicone masterbatch.

[0031] Wherein, the preparation method of the modified flame retardant is as follows: S1, 85g of ammonium polyphosphate was added to 1000g of anhydrous ethanol, followed by adding 2.5g of sodium lauryl sulfate, and stirring to obtain an ammonium polyphosphate suspension; then 250g of titanium dioxide sol was added dropwise to the 1000g ammonium polyphosphate suspension under stirring, and after the addition was completed, the mixture was stirred and reacted at 35°C for 3h. After the reaction was completed, the mixture was aged at 23°C for 14h, then filtered, washed, and dried to obtain a composite ammonium polyphosphate; the preparation method of the titanium dioxide sol was as follows: 18g of tetrabutyl titanate was added to 250g of anhydrous ethanol, followed by adding 1.8g of deionized water dropwise, and stirred at 700r / min for 1.5h to obtain; S2, adding 95g of the composite ammonium polyphosphate in step S1 to 1200g of an ethanol aqueous solution (the mass ratio of ethanol to water is 3:1), then adding 10g of γ-glycidyloxypropyltrimethoxysilane, and reacting at a constant temperature of 65°C for 2.5h. After the reaction is completed, filtering, washing, and drying to obtain silane-modified ammonium polyphosphate; S3. Add 1200 g of butanone to 95 g of the silane-modified ammonium polyphosphate in step S2, followed by 6.5 g of 2,2,6,6-tetramethyl-4-piperidinol and 2.5 g of triethylamine. The mixture is reacted at 65° C. for 3.5 h. After the reaction is completed, the mixture is filtered, washed, and dried to obtain a modified flame retardant.

[0032] The preparation method of the modified carbon nanotubes is as follows: 70 g of carbon nanotubes were added to 900 g of concentrated nitric acid (mass fraction 70%) and immersed at 45°C for 1.5 h to obtain pretreated carbon nanotubes. Subsequently, 55 g of pretreated carbon nanotubes were added to 800 g of ethanol aqueous solution (the mass ratio of ethanol to water was 3:1), followed by the addition of 6 g of γ-glycidyloxypropyltrimethoxysilane, and the mixture was stirred and reacted at 65°C for 2.5 h. After completion, the mixture was filtered, washed, and dried to obtain epoxy carbon nanotubes. 55 g of epoxy carbon nanotubes were added to 800 mL of toluene, followed by the addition of 6 g of 2-(2-hydroxy-5-benzyl)benzotriazole and 1.5 g of triethylamine, and the mixture was reacted at 75°C for 2.5 h. After completion, the mixture was filtered, washed, and dried to obtain modified carbon nanotubes.

[0033] A method for preparing a polymer composite material containing nanofibers comprises the following steps: The raw materials were weighed according to the formula and added into a high-speed mixer at a mixing speed of 800 r / min for 8 minutes. After being mixed evenly, the mixture was extruded into granules through a twin-screw extruder at a temperature of 240° C. to obtain the polymer composite material containing nanofibers. Example 2

[0034] A polymer composite material containing nanofibers, comprising the following raw materials in parts by weight: 90 parts of polypropylene, 10 parts of nylon 6, 13 parts of modified flame retardant, 4 parts of modified carbon nanotubes, 3 parts of maleic anhydride grafted polypropylene, 0.5 parts of antioxidant 1010, and 0.3 parts of silicone masterbatch.

[0035] Wherein, the preparation method of the modified flame retardant is as follows: S1. Add 80g of ammonium polyphosphate to 1000g of anhydrous ethanol, then add 2g of sodium lauryl sulfate, and stir evenly to obtain an ammonium polyphosphate suspension; then add 200g of titanium dioxide sol dropwise to the 1000g ammonium polyphosphate suspension under stirring, and after the addition is completed, stir and react at 30°C for 4h. After the reaction is completed, age at 20°C for 16h, then filter, wash, and dry to obtain composite ammonium polyphosphate; the preparation method of the titanium dioxide sol is as follows: add 15g of tetrabutyl titanate to 200g of anhydrous ethanol, then add 1.5g of deionized water dropwise, and stir at 500r / min for 2h to obtain; S2, adding 90g of the composite ammonium polyphosphate in step S1 to 1200g of an ethanol aqueous solution (the mass ratio of ethanol to water is 3:1), then adding 8g of γ-glycidyloxypropyltrimethoxysilane, and reacting at a constant temperature of 60°C for 3h. After the reaction is completed, filtering, washing, and drying to obtain silane-modified ammonium polyphosphate; S3. Add 1200 g of butanone to 90 g of the silane-modified ammonium polyphosphate in step S2, followed by 5.5 g of 2,2,6,6-tetramethyl-4-piperidinol and 2 g of triethylamine, and react at 60° C. for 4 h. After the reaction is completed, filter, wash, and dry to obtain a modified flame retardant.

[0036] The preparation method of the modified carbon nanotubes is as follows: 70 g of carbon nanotubes were added to 900 g of concentrated nitric acid (mass fraction 70%) and immersed at 40°C for 2 h to obtain pretreated carbon nanotubes. Subsequently, 50 g of pretreated carbon nanotubes were added to 800 g of ethanol aqueous solution (the mass ratio of ethanol to water was 3:1), followed by the addition of 4 g of γ-glycidyloxypropyltrimethoxysilane, and the mixture was stirred and reacted at 60°C for 3 h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain epoxy carbon nanotubes. 50 g of epoxy carbon nanotubes were added to 800 mL of toluene, followed by the addition of 4 g of 2-(2-hydroxy-5-benzyl)benzotriazole and 1 g of triethylamine, and the mixture was reacted at 70°C for 3 h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain modified carbon nanotubes.

[0037] A method for preparing a polymer composite material containing nanofibers comprises the following steps: The raw materials were weighed according to the formula and added into a high-speed mixer at a mixing speed of 700 r / min for 10 min. After uniform mixing, the mixture was extruded into granules through a twin-screw extruder at a temperature of 240° C. to obtain the polymer composite material containing nanofibers. Example 3

[0038] A polymer composite material containing nanofibers, comprising the following raw materials in parts by weight: 100 parts of polypropylene, 15 parts of nylon 6, 16 parts of modified flame retardant, 7 parts of modified carbon nanotubes, 5 parts of maleic anhydride grafted polypropylene, 0.8 parts of antioxidant 1010, and 0.5 parts of silicone masterbatch.

[0039] Wherein, the preparation method of the modified flame retardant is as follows: S1. Add 90g of ammonium polyphosphate to 1000g of anhydrous ethanol, then add 3g of sodium lauryl sulfate, and stir evenly to obtain an ammonium polyphosphate suspension; then add 300g of titanium dioxide sol dropwise to the 1000g ammonium polyphosphate suspension under stirring, and after the addition is completed, stir and react at 40°C for 2h. After the reaction is completed, age at 25°C for 12h, then filter, wash, and dry to obtain a composite ammonium polyphosphate; the preparation method of the titanium dioxide sol is as follows: add 20g of tetrabutyl titanate to 300g of anhydrous ethanol, then add 2g of deionized water dropwise, and stir at 800r / min for 1h to obtain; S2, adding 100g of the composite ammonium polyphosphate in step S1 to 1200g of an ethanol aqueous solution (the mass ratio of ethanol to water is 3:1), then adding 11g of γ-glycidyloxypropyltrimethoxysilane, and reacting at a constant temperature of 70°C for 2h. After the reaction is completed, filtering, washing, and drying to obtain silane-modified ammonium polyphosphate; S3. Add 1200 g of butanone to 100 g of the silane-modified ammonium polyphosphate in step S2, followed by 7.5 g of 2,2,6,6-tetramethyl-4-piperidinol and 3 g of triethylamine, and react at 70° C. for 3 h. After the reaction is completed, filter, wash, and dry to obtain a modified flame retardant.

[0040] The preparation method of the modified carbon nanotubes is as follows: 70 g of carbon nanotubes were added to 900 g of concentrated nitric acid (mass fraction 70%) and immersed at 50° C. for 1 h to obtain pretreated carbon nanotubes. Subsequently, 60 g of pretreated carbon nanotubes were added to 800 g of ethanol aqueous solution (the mass ratio of ethanol to water was 3:1), followed by the addition of 7 g of γ-glycidyloxypropyltrimethoxysilane, and stirred at 70° C. for 2 h. After completion, the mixture was filtered, washed, and dried to obtain epoxy carbon nanotubes. 60 g of epoxy carbon nanotubes were added to 800 mL of toluene, followed by the addition of 7 g of 2-(2-hydroxy-5-benzyl)benzotriazole and 2 g of triethylamine, and reacted at 80° C. for 2 h. After completion, the reaction was filtered, washed, and dried to obtain modified carbon nanotubes.

[0041] A method for preparing a polymer composite material containing nanofibers comprises the following steps: The raw materials were weighed according to the formula and added into a high-speed mixer at a mixing speed of 900 r / min for 5 minutes. After being mixed evenly, the mixture was granulated by twin-screw extrusion at a temperature of 240° C. to obtain the polymer composite material containing nanofibers. Comparative Example 1

[0042] A polymer composite material containing nanofibers, comprising the following raw materials in parts by weight: 95 parts of polypropylene, 13 parts of nylon 6, 15 parts of modified flame retardant, 6 parts of modified carbon nanotubes, 4 parts of maleic anhydride grafted polypropylene, 0.7 parts of antioxidant 1010, and 0.4 parts of silicone masterbatch.

[0043] Wherein, the preparation method of the modified flame retardant is as follows: S1, 85g of ammonium polyphosphate was added to 1000g of anhydrous ethanol, followed by adding 2.5g of sodium lauryl sulfate, and stirring to obtain an ammonium polyphosphate suspension; then 250g of titanium dioxide sol was added dropwise to the 1000g ammonium polyphosphate suspension under stirring, and after the addition was completed, the mixture was stirred and reacted at 35°C for 3h. After the reaction was completed, the mixture was aged at 23°C for 14h, then filtered, washed, and dried to obtain a composite ammonium polyphosphate; the preparation method of the titanium dioxide sol was as follows: 18g of tetrabutyl titanate was added to 250g of anhydrous ethanol, followed by adding 1.8g of deionized water dropwise, and stirred at 700r / min for 1.5h to obtain; S2. Add 95 g of the composite ammonium polyphosphate prepared in step S1 to 1200 g of an ethanol aqueous solution (the mass ratio of ethanol to water is 3:1), and then add 10 g of γ-glycidyloxypropyltrimethoxysilane. The mixture is reacted at a constant temperature of 65° C. for 2.5 h. After the reaction is completed, the mixture is filtered, washed, and dried to obtain a modified flame retardant.

[0044] The preparation method of the modified carbon nanotubes is as follows: 70 g of carbon nanotubes were added to 900 g of concentrated nitric acid (mass fraction 70%) and immersed at 45°C for 1.5 h to obtain pretreated carbon nanotubes. Subsequently, 55 g of pretreated carbon nanotubes were added to 800 g of ethanol aqueous solution (the mass ratio of ethanol to water was 3:1), followed by the addition of 6 g of γ-glycidyloxypropyltrimethoxysilane, and the mixture was stirred and reacted at 65°C for 2.5 h. After completion, the mixture was filtered, washed, and dried to obtain epoxy carbon nanotubes. 55 g of epoxy carbon nanotubes were added to 800 mL of toluene, followed by the addition of 6 g of 2-(2-hydroxy-5-benzyl)benzotriazole and 1.5 g of triethylamine, and the mixture was reacted at 75°C for 2.5 h. After completion, the mixture was filtered, washed, and dried to obtain modified carbon nanotubes.

[0045] A method for preparing a polymer composite material containing nanofibers comprises the following steps: The raw materials were weighed according to the formula and added into a high-speed mixer at a mixing speed of 800 r / min for 8 minutes. After being mixed evenly, the mixture was extruded into granules through a twin-screw extruder at a temperature of 240° C. to obtain the polymer composite material containing nanofibers.

[0046] Compared with Example 1, this comparative example does not introduce 2,2,6,6-tetramethyl-4-piperidinol into the flame retardant. Comparative Example 2

[0047] A polymer composite material containing nanofibers, comprising the following raw materials in parts by weight: 95 parts of polypropylene, 13 parts of nylon 6, 15 parts of modified flame retardant, 6 parts of modified carbon nanotubes, 4 parts of maleic anhydride grafted polypropylene, 0.7 parts of antioxidant 1010, and 0.4 parts of silicone masterbatch.

[0048] Wherein, the preparation method of the modified flame retardant is as follows: S1, 85g of ammonium polyphosphate was added to 1000g of anhydrous ethanol, followed by adding 2.5g of sodium lauryl sulfate, and stirring to obtain an ammonium polyphosphate suspension; then 250g of titanium dioxide sol was added dropwise to the 1000g ammonium polyphosphate suspension under stirring, and after the addition was completed, the mixture was stirred and reacted at 35°C for 3h. After the reaction was completed, the mixture was aged at 23°C for 14h, then filtered, washed, and dried to obtain a composite ammonium polyphosphate; the preparation method of the titanium dioxide sol was as follows: 18g of tetrabutyl titanate was added to 250g of anhydrous ethanol, followed by adding 1.8g of deionized water dropwise, and stirred at 700r / min for 1.5h to obtain; S2, adding 95g of the composite ammonium polyphosphate in step S1 to 1200g of an ethanol aqueous solution (the mass ratio of ethanol to water is 3:1), then adding 10g of γ-glycidyloxypropyltrimethoxysilane, and reacting at a constant temperature of 65°C for 2.5h. After the reaction is completed, filtering, washing, and drying to obtain silane-modified ammonium polyphosphate; S3. Add 1200 g of butanone to 95 g of the silane-modified ammonium polyphosphate in step S2, followed by 6.5 g of 2,2,6,6-tetramethyl-4-piperidinol and 2.5 g of triethylamine. The mixture is reacted at 65° C. for 3.5 h. After the reaction is completed, the mixture is filtered, washed, and dried to obtain a modified flame retardant.

[0049] The preparation method of the modified carbon nanotubes is as follows: 70 g of carbon nanotubes were added to 900 g of concentrated nitric acid (mass fraction 70%) and immersed at 45°C for 1.5 h to obtain pretreated carbon nanotubes. Subsequently, 55 g of pretreated carbon nanotubes were added to 800 g of ethanol aqueous solution (the mass ratio of ethanol to water was 3:1), followed by the addition of 6 g of γ-glycidyloxypropyltrimethoxysilane, and the mixture was stirred and reacted at 65°C for 2.5 h. After completion, the mixture was filtered, washed, and dried to obtain modified carbon nanotubes.

[0050] A method for preparing a polymer composite material containing nanofibers comprises the following steps: The raw materials were weighed according to the formula and added into a high-speed mixer at a mixing speed of 800 r / min for 8 minutes. After being mixed evenly, the mixture was extruded into granules through a twin-screw extruder at a temperature of 240° C. to obtain the polymer composite material containing nanofibers.

[0051] Compared with Example 1, in this comparative example, 2-(2-hydroxy-5-benzyl)benzotriazole was not introduced onto the carbon nanotubes. Comparative Example 3

[0052] A polymer composite material containing nanofibers, comprising the following raw materials in parts by weight: 95 parts of polypropylene, 13 parts of nylon 6, 15 parts of modified flame retardant, 6 parts of modified carbon nanotubes, 4 parts of maleic anhydride grafted polypropylene, 0.7 parts of antioxidant 1010, and 0.4 parts of silicone masterbatch.

[0053] Wherein, the preparation method of the modified flame retardant is as follows: S1, 85g of ammonium polyphosphate was added to 1000g of anhydrous ethanol, followed by adding 2.5g of sodium lauryl sulfate, and stirring to obtain an ammonium polyphosphate suspension; then 250g of titanium dioxide sol was added dropwise to the 1000g ammonium polyphosphate suspension under stirring, and after the addition was completed, the mixture was stirred and reacted at 35°C for 3h. After the reaction was completed, the mixture was aged at 23°C for 14h, then filtered, washed, and dried to obtain a composite ammonium polyphosphate; the preparation method of the titanium dioxide sol was as follows: 18g of tetrabutyl titanate was added to 250g of anhydrous ethanol, followed by adding 1.8g of deionized water dropwise, and stirred at 700r / min for 1.5h to obtain; S2. Mix 95 g of the composite ammonium polyphosphate in step S1 and 6.5 g of 2,2,6,6-tetramethyl-4-piperidinol to obtain a modified flame retardant.

[0054] The preparation method of the modified carbon nanotubes is as follows: 70 g of carbon nanotubes were added to 900 g of concentrated nitric acid (mass fraction 70%) and immersed at 45°C for 1.5 h to obtain pretreated carbon nanotubes. Subsequently, 55 g of the pretreated carbon nanotubes were mixed with 6 g of 2-(2-hydroxy-5-benzyl)benzotriazole to obtain modified carbon nanotubes.

[0055] A method for preparing a polymer composite material containing nanofibers comprises the following steps: The raw materials were weighed according to the formula and added into a high-speed mixer at a mixing speed of 800 r / min for 8 minutes. After being mixed evenly, the mixture was extruded into granules through a twin-screw extruder at a temperature of 240° C. to obtain the polymer composite material containing nanofibers.

[0056] Compared with Example 1, the modified flame retardant of this comparative example is prepared by physical blending of composite ammonium polyphosphate and 2,2,6,6-tetramethyl-4-piperidinol; the modified carbon nanotubes are prepared by physical blending of pretreated carbon nanotubes and 2-(2-hydroxy-5-benzyl)benzotriazole. Comparative Example 4

[0057] A polymer composite material containing nanofibers, comprising the following raw materials in parts by weight: 95 parts of polypropylene, 13 parts of nylon 6, 21 parts of modified flame retardant, 4 parts of maleic anhydride grafted polypropylene, 0.7 parts of antioxidant 1010, and 0.4 parts of silicone masterbatch.

[0058] Wherein, the preparation method of the modified flame retardant is as follows: S1, 85g of ammonium polyphosphate was added to 1000g of anhydrous ethanol, followed by adding 2.5g of sodium lauryl sulfate, and stirring to obtain an ammonium polyphosphate suspension; then 250g of titanium dioxide sol was added dropwise to the 1000g ammonium polyphosphate suspension under stirring, and after the addition was completed, the mixture was stirred and reacted at 35°C for 3h. After the reaction was completed, the mixture was aged at 23°C for 14h, then filtered, washed, and dried to obtain a composite ammonium polyphosphate; the preparation method of the titanium dioxide sol was as follows: 18g of tetrabutyl titanate was added to 250g of anhydrous ethanol, followed by adding 1.8g of deionized water dropwise, and stirred at 700r / min for 1.5h to obtain; S2, adding 95g of the composite ammonium polyphosphate in step S1 to 1200g of an ethanol aqueous solution (the mass ratio of ethanol to water is 3:1), then adding 10g of γ-glycidyloxypropyltrimethoxysilane, and reacting at a constant temperature of 65°C for 2.5h. After the reaction is completed, filtering, washing, and drying to obtain silane-modified ammonium polyphosphate; S3. Add 1200 g of butanone to 95 g of the silane-modified ammonium polyphosphate in step S2, followed by 6.5 g of 2,2,6,6-tetramethyl-4-piperidinol and 2.5 g of triethylamine. The mixture is reacted at 65° C. for 3.5 h. After the reaction is completed, the mixture is filtered, washed, and dried to obtain a modified flame retardant.

[0059] A method for preparing a polymer composite material containing nanofibers comprises the following steps: The raw materials were weighed according to the formula and added into a high-speed mixer at a mixing speed of 800 r / min for 8 minutes. After being mixed evenly, the mixture was extruded into granules through a twin-screw extruder at a temperature of 240° C. to obtain the polymer composite material containing nanofibers.

[0060] Compared with Example 1, no modified carbon nanotubes were added in this comparative example.

[0061] The polymer composite materials prepared in Examples 1-3 and Comparative Examples 1-4 were injected into specimens and subjected to performance tests. The tensile strength and elongation at break were tested according to GB / T 1040.2-2022 "Determination of tensile properties of plastics - Part 2: Test conditions for molded and extruded plastics", with a specimen size of 180 mm × 10 mm × 4 mm and a tensile speed of 10 mm / min. The limiting oxygen index was tested according to GB / T 2406.2-2009, with a specimen size of type I and an ignition method of A. The UV aging resistance was tested according to GB / T 16422.3-2022 "Plastics - Laboratory light source exposure test methods - Part 3: Fluorescent UV lamps", with an UV intensity of 210 W / m 2, aging temperature 60℃, aging time 240h, after aging, the tensile strength and elongation at break retention of the test samples were tested. The test results are shown in Table 1 below.

[0062] Table 1 Tensile strength (MPa) Elongation at break (%) Limiting oxygen index (%) Tensile strength retention rate (%) Retention rate of elongation at break (%) Example 1 40.3 127 35.3 92.1 90.4 Example 2 37.9 136 34.1 90.6 87.5 Example 3 39.2 114 34.5 91.7 89.2 Comparative Example 1 36.1 105 34.6 80.3 77.1 Comparative Example 2 35.7 102 34.9 82.5 79.3 Comparative Example 3 33.8 97 35.1 86.4 83.8 Comparative Example 4 32.6 84 29.7 83.2 80.6 As can be seen from Table 1 above, the polymer composite material containing nanofibers prepared in the present invention has good mechanical properties, flame retardant properties and UV aging resistance, and has good application prospects.

[0063] The above content is a further detailed description of the present invention in combination with specific implementation examples. It cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, they can make several simple deductions or substitutions without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

[0064] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A polymer composite material containing nanofibers, characterized in that: Calculated by weight, it includes the following raw materials: 90-100 parts of polypropylene, 10-15 parts of nylon 6, 13-16 parts of modified flame retardant, 4-7 parts of modified carbon nanotubes, 3-5 parts of compatibilizer, 0.5-0.8 parts of antioxidant, and 0.3-0.5 parts of lubricant.

2. The polymer composite material containing nanofibers according to claim 1, characterized in that: The invention comprises the following raw materials in parts by weight: 95-100 parts of polypropylene, 10-13 parts of nylon 6, 13-18 parts of modified flame retardant, 4-6 parts of modified carbon nanotubes, 3-4 parts of compatibilizer, 0.5-0.7 parts of antioxidant, and 0.4-0.5 parts of lubricant; the compatibilizer is maleic anhydride grafted polypropylene, the antioxidant is one or more of antioxidant 168, antioxidant 1010, and antioxidant 1098; and the lubricant is silicone masterbatch.

3. The polymer composite material containing nanofibers according to claim 1, characterized in that: The preparation method of the modified flame retardant is as follows: S1, adding ammonium polyphosphate to anhydrous ethanol, then adding sodium lauryl sulfate, stirring evenly to obtain an ammonium polyphosphate suspension; then adding titanium dioxide sol dropwise to the ammonium polyphosphate suspension under stirring, stirring and reacting after the addition is completed, aging after the reaction is completed, then filtering, washing, and drying to obtain composite ammonium polyphosphate; S2, adding the composite ammonium polyphosphate to an ethanol aqueous solution, followed by adding γ-glycidyloxypropyltrimethoxysilane, and reacting at a constant temperature to obtain silane-modified ammonium polyphosphate; S3. Add silane-modified ammonium polyphosphate to butanone, and then add 2,2,6,6-tetramethyl-4-piperidinol and triethylamine to carry out a ring-opening reaction to obtain a modified flame retardant.

4. The polymer composite material containing nanofibers according to claim 3, characterized in that: In step S1, the mass ratio of ammonium polyphosphate, sodium lauryl sulfate, and anhydrous ethanol is 80-90:2-3:1000, the mass ratio of the ammonium polyphosphate suspension and the titanium dioxide sol is 1000:200-300, the stirring reaction temperature is 30-40°C, the time is 2-4h, and the aging temperature is 20-25°C, and the time is 12-16h; the preparation method of the titanium dioxide sol is as follows: 15-20g of tetrabutyl titanate is added to 200-300g of anhydrous ethanol, followed by dropwise addition of 1.5-2g of deionized water, and stirring at 500-800r / min for 1-2h.

5. The polymer composite material containing nanofibers according to claim 3, characterized in that: In step S2, the mass ratio of the composite ammonium polyphosphate to γ-glycidyloxypropyltrimethoxysilane is 90-100:8-11, the temperature of the isothermal reaction is 60-70° C., and the time is 2-3 hours.

6. The polymer composite material containing nanofibers according to claim 3, characterized in that: In step S3, the mass ratio of silane-modified ammonium polyphosphate, 2,2,6,6-tetramethyl-4-piperidinol, and triethylamine is 90-100:5.5-7.5:2-3, and the temperature of the ring-opening reaction is 60-70° C., and the time is 3-4 hours.

7. The polymer composite material containing nanofibers according to claim 1, characterized in that: The preparation method of the modified carbon nanotubes is as follows: The carbon nanotubes are added to concentrated nitric acid for immersion treatment to obtain pretreated carbon nanotubes after the treatment is completed; the pretreated carbon nanotubes are then added to an ethanol aqueous solution, followed by the addition of γ-glycidyloxypropyltrimethoxysilane, and stirred for reaction to obtain epoxy carbon nanotubes; the epoxy carbon nanotubes are added to toluene, followed by the addition of 2-(2-hydroxy-5-benzyl)benzotriazole and triethylamine, and heated for reaction to obtain modified carbon nanotubes.

8. The polymer composite material containing nanofibers according to claim 7, characterized in that: The temperature of the immersion treatment is 40-50°C, and the time is 1-2h; the mass ratio of the pretreated carbon nanotubes and γ-glycidyloxypropyltrimethoxysilane is 50-60:4-7, the temperature of the stirring reaction is 60-70°C, and the time is 2-3h; the mass ratio of the epoxy carbon nanotubes, 2-(2-hydroxy-5-benzyl)benzotriazole, and triethylamine is 50-60:4-7:1-2, the temperature of the heating reaction is 70-80°C, and the time is 2-3h.

9. A method for preparing a polymer composite material containing nanofibers according to any one of claims 1 to 8, characterized in that: The following steps are involved: The raw materials are weighed according to the formula, added into a high-speed mixer, mixed evenly, and then granulated by twin-screw extrusion to obtain the polymer composite material containing nanofibers.

10. The preparation method according to claim 9, characterized in that The mixing speed is 700-900 r / min, and the mixing time is 5-10 min; the extrusion temperature is 230-250°C.