Nylon composite material, preparation method and application thereof

Abstract

The invention belongs to the technical field of high polymer materials, and particularly relates to a nylon composite material as well as a preparation method and application thereof. The nylon composite material is prepared from the following raw materials in parts by weight: 50-80 parts of nylon resin, 10-30 parts of a reinforcing agent, 5-15 parts of a toughening agent, 5-20 parts of a flame retardant, 0.5-3 parts of a lubricating agent, 0.1-2 parts of an antioxidant, 3-8 parts of a compound functional intermediate product I, 2-10 parts of inorganic filler, 4-15 parts of a compound functional intermediate product II and 2-6 parts of a compound functional intermediate product III, the compound functional intermediate product I is prepared from the following raw materials in parts by weight: 10 to 20 parts of sulfonated polybenzimidazole, 5 to 15 parts of montmorillonite and 1 to 5 parts of gamma-aminopropyltriethoxysilane; the compound functional intermediate product II is prepared from the following raw materials in parts by weight: 15 to 30 parts of hydrogenated styrene-butadiene block copolymer, 5 to 15 parts of dioctyl adipate and 2 to 8 parts of compatilizer; the compound functional intermediate product III is prepared from the following raw materials in parts by weight: 5 to 12 parts of nano zinc oxide, 2 to 6 parts of graphene and 1 to 4 parts of polydopamine.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and in particular relates to a nylon composite material, a preparation method and applications thereof. Background Art

[0002] Nylon, a high-performance engineering plastic, boasts excellent mechanical properties, wear resistance, and chemical corrosion resistance, making it widely used in the automotive, electronics, and machinery sectors. However, pure nylon materials still have shortcomings in certain performance aspects, such as poor flame retardancy, potential for improved impact strength, and susceptibility to aging under high-temperature or long-term use, which limits their application in a wider range of fields.

[0003] To improve the performance of nylon materials, various additives are commonly added to create nylon composites. For example, reinforcing agents can increase the material's strength and rigidity; toughening agents can improve its impact toughness; and flame retardants can impart flame retardancy. However, current nylon composites often struggle to balance these various properties. For example, increasing strength can reduce toughness, while adding flame retardants can adversely affect the material's mechanical properties.

[0004] Therefore, developing a nylon composite material with excellent comprehensive performance has important practical significance. Summary of the Invention

[0005] In response to the deficiencies in the prior art, the present invention provides a nylon composite material, a nylon product, and a preparation method thereof. The nylon composite material uses a composite acid-resistant intermediate product prepared from a variety of materials as an acid-resistant component, adds a composite cold-resistant toughening intermediate product having both cold-resistant and low-temperature toughening properties, and a newly added composite functional intermediate product. The composite functional intermediate product can be combined with the first two to produce different new effects, so that the material has excellent comprehensive performance. The preparation method is simple and easy, and is suitable for industrial production.

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

[0007] A nylon composite material, wherein the raw materials for preparing the nylon composite material include, by weight, 50-80 parts of nylon resin, 10-30 parts of reinforcing agent, 5-15 parts of toughening agent, 5-20 parts of flame retardant, 0.5-3 parts of lubricant, 0.1-2 parts of antioxidant, 3-8 parts of composite functional intermediate product 1, 2-10 parts of inorganic filler, 4-15 parts of composite functional intermediate product 2, and 2-6 parts of composite functional intermediate product 3; the raw materials for preparing the composite functional intermediate product 1 are by weight The composite functional intermediate product comprises, by weight, 10-20 parts of sulfonated polybenzimidazole, 5-15 parts of montmorillonite, and 1-5 parts of γ-aminopropyltriethoxysilane; the raw materials for preparing the composite functional intermediate product II comprise, by weight, 15-30 parts of hydrogenated styrene-butadiene block copolymer, 5-15 parts of dioctyl adipate, and 2-8 parts of a compatibilizer; the raw materials for preparing the composite functional intermediate product III comprise, by weight, 5-12 parts of nano zinc oxide, 2-6 parts of graphene, and 1-4 parts of polydopamine.

[0008] As a preferred embodiment of the present invention, the nylon resin is at least one of nylon 6, nylon 66, nylon 11, and nylon 12; the reinforcing agent is at least one of glass fiber, carbon fiber, and basalt fiber, and the length of the reinforcing agent is 3-10 mm; the toughening agent is at least one of maleic anhydride grafted ethylene-octene copolymer, maleic anhydride grafted polypropylene, and ethylene-vinyl acetate copolymer; the flame retardant is a halogen-free flame retardant selected from at least one of magnesium hydroxide, aluminum hydroxide, and ammonium polyphosphate; the lubricant is at least one of calcium stearate, zinc stearate, and ethylene bisstearamide; and the antioxidant is at least one of hindered phenol antioxidants and phosphite antioxidants.

[0009] As a preferred embodiment of the present invention, the method for preparing the composite functional intermediate product 1 comprises the following steps:

[0010] A1. Weigh sulfonated polybenzimidazole, montmorillonite, and γ-aminopropyltriethoxysilane in parts by weight;

[0011] A2. Add montmorillonite to a 5-10% by mass hydrochloric acid solution, stir at 60-80°C for 2-4 hours, filter, wash until neutral, and dry to obtain modified montmorillonite;

[0012] A3. Add sulfonated polybenzimidazole, modified montmorillonite and γ-aminopropyltriethoxysilane to an ethanol aqueous solution, wherein the volume ratio of ethanol to water is 3:1-5:1, stir at a temperature of 50-70°C and a rotation speed of 300-500 r / min for 3-6 hours, and then dry at a temperature of 80-100°C to constant weight to obtain a composite functional intermediate product 1.

[0013] As a preferred embodiment of the present invention, the preparation method of the composite functional intermediate product 2 comprises the following steps:

[0014] B1. Weigh hydrogenated styrene-butadiene block copolymer, dioctyl adipate and compatibilizer in parts by weight;

[0015] B2. Add hydrogenated styrene-butadiene block copolymer into a twin-screw extruder and melt it at a temperature of 180-220° C. and a screw speed of 150-250 r / min. Then, add dioctyl adipate and a compatibilizer through a side feed port, continue melt blending for 5-10 minutes, and then extrude.

[0016] B3. Cool the extrudate, granulate it, and dry it at a temperature of 70-90° C. for 3-5 hours to obtain a composite functional intermediate product II.

[0017] As a preferred embodiment of the present invention, the compatibilizer is at least one of maleic anhydride grafted styrene-ethylene-butylene-styrene block copolymer and maleic anhydride grafted polyethylene.

[0018] As a preferred embodiment of the present invention, the preparation method of the composite functional intermediate product 3 comprises the following steps:

[0019] C1. Weigh nano zinc oxide, graphene and polydopamine by weight;

[0020] C2. Dispersing the graphene in deionized water and ultrasonically treating for 30-60 min to obtain a graphene dispersion;

[0021] C3. Add nano zinc oxide to the graphene dispersion, stir evenly, then add polydopamine, and react at a temperature of 30-50°C and a rotation speed of 200-400 r / min for 4-8 hours;

[0022] C4. The reaction product is centrifuged, washed alternately with deionized water and ethanol for 3-5 times, and vacuum dried at a temperature of 60-80° C. for 12-24 hours to obtain a composite functional intermediate product three; the particle size of the nano zinc oxide is 20-50 nm; the graphene is obtained by reducing graphene oxide, and the flake diameter is 0.5-2 μm.

[0023] A method for preparing the nylon composite material as described above, the preparation method comprising the following steps:

[0024] S1. Place the nylon resin in a vacuum drying oven to remove moisture; place the reinforcing agent in a plasma treatment device for surface treatment to enhance its bonding with the substrate; add the inorganic filler to a 1-3% by mass silane coupling agent ethanol solution, stir, and then remove and dry to complete the surface modification;

[0025] S2, first add the pretreated nylon resin, toughening agent, and flame retardant into a high-speed mixer for a first high-speed mixing; then add the lubricant and antioxidant for a second high-speed mixing; finally, add the composite functional intermediate product 1, the pretreated inorganic filler, the composite functional intermediate product 2, and the composite functional intermediate product 3, and perform a third high-speed mixing to obtain a premix;

[0026] S3. Add the premix to the main feed port of a twin-screw extruder and set the temperature of each section of the twin-screw extruder; add the pretreated reinforcing agent to the twin-screw extruder through the side feed port, and control the ratio of the side feed rate to the main feed rate to be 1:(3-5); control the screw speed to be 200-300 r / min; during the extrusion process, monitor the melt viscosity in real time using an online viscometer; when the viscosity deviates from the set range (1000-3000 Pa·s), adjust the screw speed by ±10 r / min to make corrections; and water-cool the extrudate to room temperature and then pelletize to obtain primary pellets;

[0027] S4. Dry the primary particles in a fluidized bed drying machine to remove surface moisture; then place the dried primary particles in a hot air circulation oven for a second drying to control the moisture content to ≤0.05%; finally, sieve the particles after the second drying to obtain a nylon composite material.

[0028] As a preferred embodiment of the present invention, the drying conditions of the nylon resin in step S1 are drying at 100-120° C. for 8-12 hours; the surface treatment conditions of the reinforcing agent are at a power of 50-100 W and a treatment time of 5-15 minutes; the first high-speed mixing conditions in step S2 are mixing at a speed of 600-800 r / min for 2-3 minutes; the second high-speed mixing conditions are mixing at a speed of 800-1000 r / min for 1-2 minutes; and the third high-speed mixing conditions are mixing at a speed of 1000-1200 r / min for 3-5 minutes.

[0029] As a preferred embodiment of the present invention, the temperature of each section of the twin-screw extruder in step S3 is: feeding section 200-220°C, compression section 220-240°C, melting section 240-260°C, and homogenization section 230-250°C; the primary drying conditions in step S4 are: drying at 80-90°C for 1-2 hours; and the secondary drying conditions are: secondary drying at 100-110°C for 3-4 hours.

[0030] The nylon composite material described above is used to prepare low-temperature pipe fittings, electronic and electrical appliance housings, and nylon products for automotive parts.

[0031] Beneficial effects of the present invention:

[0032] 1. Sulfonated polybenzimidazole molecules contain sulfonic acid groups (-SO3H), which have good hydrophilicity and chemical stability. They can form a stable ion barrier in an acidic environment and effectively block H + Acidic ions penetrate into the nylon matrix. The interlayer spacing of montmorillonite treated with hydrochloric acid increases, and its lamellar structure can act as a physical barrier to further delay the diffusion of acidic media. The amino group (-NH2) in γ-aminopropyltriethoxysilane can undergo acid-base interaction with the sulfonic acid group of sulfonated polybenzimidazole, while its ethoxy group (-OC2H5) can form a covalent bond with the hydroxyl group (-OH) on the surface of montmorillonite, so that the three are tightly bound to form a dense acid-resistant network. This synergistic effect reduces the mass loss rate of nylon material after immersion in acidic conditions (such as 5% by mass sulfuric acid solution) to less than 10%, and increases the tensile strength retention rate to more than 35%, which is far superior to materials modified with a single acid-resistant additive.

[0033] 2. After hydrogenation, the double bonds in the molecular chain of hydrogenated styrene-butadiene block copolymer (HSBR) are saturated, allowing it to maintain good elasticity and flexibility in low-temperature environments. The styrene segment provides rigid support, while the butadiene segment provides low-temperature elasticity, effectively absorbing external impact energy. Dioctyl adipate, as a cold-resistant plasticizer, can penetrate between polymer chains, reduce intermolecular forces, and lower the glass transition temperature (Tg) of nylon materials by 10-15°C, allowing it to maintain good flexibility under extreme low-temperature conditions such as -40°C. Under the action of the compatibilizer, the two form a uniformly dispersed elastomeric phase. When the material is subjected to low-temperature impact, the elastomeric phase can induce silver streaks and inhibit crack propagation, increasing the low-temperature impact strength of the nylon material (-40°C) by more than 50% compared to unadded materials. The weather resistance and aging resistance of hydrogenated styrene-butadiene block copolymer are better than those of unhydrogenated elastomers, and it is not prone to degradation or hardening in long-term low-temperature environments. The compatibility of dioctyl adipate with the nylon matrix is ​​significantly enhanced by the addition of a compatibilizer (such as maleic anhydride-grafted styrene-ethylene-butylene-styrene block copolymer), preventing the degradation of material properties caused by plasticizer migration at low temperatures. Experiments have shown that after 50 cycles from -40°C to room temperature, nylon materials containing this composite intermediate retain over 85% of their impact strength, while the retention rate of materials without this intermediate is only around 50%, demonstrating excellent low-temperature performance stability.

[0034] 3. Polydopamine forms a chemical bridge at the interface of the two intermediate products (catechol groups react with amino and hydroxyl groups), increasing the compatibility of composite functional intermediate product 1 and composite functional intermediate product 3 by 40%, thus avoiding interfacial delamination. The antibacterial properties of nano-zinc oxide (99% inhibition rate against Escherichia coli) can prevent material degradation caused by microbial growth in acidic environments; synergistically with antioxidants, the material's tensile strength retention rate in a 120°C thermal oxidative aging test is increased to over 85% (compared to 60-70% for traditional materials). In addition, graphene's thermal conductivity (5000W / m·K) can accelerate heat dissipation within the material, reducing the impact of temperature fluctuations on structural stability.

[0035] 4. The high strength of graphene (130GPa) complements the flexibility of hydrogenated styrene-butadiene block copolymer, keeping the fluctuation of the material's tensile strength within 5% within the temperature range of -40°C to 80°C (tensile strength reaches 85-95MPa at room temperature and remains at 80-90MPa at -40°C). Nano-zinc oxide (particle size 20-50nm) uniformly fills the gaps between the elastic phases, inhibiting excessive shrinkage of the elastomer at low temperatures. After 50 cycles from -40°C to room temperature, the material retains over 90% of its tensile strength, far exceeding the 70-75% retention of the second-modified composite functional intermediate. DETAILED DESCRIPTION

[0036] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] Example 1

[0038] Preparation of composite functional intermediate 1:

[0039] A1. Weigh 15 parts of sulfonated polybenzimidazole, 10 parts of montmorillonite, and 3 parts of γ-aminopropyltriethoxysilane by weight.

[0040] A2. Add montmorillonite to a hydrochloric acid solution with a mass fraction of 8%, stir at 70°C for 3 hours, filter, wash until neutral, and dry to obtain modified montmorillonite.

[0041] A3. Add sulfonated polybenzimidazole, modified montmorillonite and γ-aminopropyltriethoxysilane to an ethanol aqueous solution with a volume ratio of ethanol to water of 4:1. Stir at 60°C and 400 r / min for 4.5 hours, and then dry at 90°C to constant weight to obtain a composite functional intermediate product 1.

[0042] Preparation of composite functional intermediate 2:

[0043] B1. Weigh 22 parts of hydrogenated styrene-butadiene block copolymer, 10 parts of dioctyl adipate, and 5 parts of a compatibilizer (maleic anhydride grafted styrene-ethylene-butylene-styrene block copolymer) by weight.

[0044] B2. Add hydrogenated styrene-butadiene block copolymer into a twin-screw extruder and melt it at a temperature of 200° C. and a screw speed of 200 r / min. Then, add dioctyl adipate and a compatibilizer through a side feed port, continue melt blending for 7 minutes, and then extrude.

[0045] B3. The extrudate is cooled, granulated, and dried at 80° C. for 4 h to obtain a second composite functional intermediate product.

[0046] Preparation of composite functional intermediate three:

[0047] C1. Weigh 8 parts of nano zinc oxide, 4 parts of graphene, and 2.5 parts of polydopamine by weight.

[0048] C2. Disperse the graphene in deionized water and perform ultrasonic treatment for 45 min to obtain a graphene dispersion.

[0049] C3. Add nano zinc oxide to the graphene dispersion, stir evenly, then add polydopamine, and react at a temperature of 40°C and a rotation speed of 300 r / min for 6 hours.

[0050] C4. The reaction product was centrifuged and washed alternately with deionized water and ethanol four times, and vacuum dried at 70° C. for 18 h to obtain a composite functional intermediate product three.

[0051] Preparation of nylon composite materials:

[0052] Raw material preparation: 65 parts of nylon resin (nylon 66), 20 parts of reinforcing agent (glass fiber, length 6 mm), 10 parts of toughening agent (maleic anhydride grafted ethylene-octene copolymer), 12 parts of flame retardant (magnesium hydroxide), 1.5 parts of lubricant (calcium stearate), 0.8 parts of antioxidant (hindered phenol antioxidant 1010), 5 parts of the above-prepared composite functional intermediate product 1, 6 parts of inorganic filler (calcium carbonate), 8 parts of composite functional intermediate product 2, and 4 parts of composite functional intermediate product 3.

[0053] A method for preparing a nylon composite material, comprising the following steps:

[0054] S1. Pretreatment: Dry the nylon resin in a vacuum drying oven at 110°C for 10 hours; place the reinforcing agent in a plasma treatment device and perform surface treatment at a power of 75W and a treatment time of 10 minutes; add the inorganic filler to a 2% by mass silane coupling agent ethanol solution and stir, then remove and dry to complete the surface modification.

[0055] S2. Mixing: First, add the pretreated nylon resin, toughening agent, and flame retardant into a high-speed mixer, and perform the first high-speed mixing at a speed of 700 r / min for 2.5 min; then add the lubricant and antioxidant, and perform the second high-speed mixing at a speed of 900 r / min for 1.5 min; finally, add the composite functional intermediate product 1, the pretreated inorganic filler, the composite functional intermediate product 2, and the composite functional intermediate product 3, and perform the third high-speed mixing at a speed of 1100 r / min for 4 min to obtain a premix.

[0056] S3. Extrusion: Add the premix to the main feed port of a twin-screw extruder. Set the temperatures in each section of the twin-screw extruder to: 210°C for the feed section, 230°C for the compression section, 250°C for the melt section, and 240°C for the homogenization section. Add the pretreated reinforcing agent to the twin-screw extruder through the side feed port, controlling the ratio of the side feed rate to the main feed rate to be 1:4. The screw speed is controlled at 250 r / min. During the extrusion process, the melt viscosity is monitored in real time using an online viscometer. When the viscosity deviates from the set range (1000-3000 Pa·s), the screw speed is adjusted by ±10 r / min to correct it. The extrudate is water-cooled to room temperature and then pelletized to obtain primary pellets.

[0057] S4. Drying and sieving: Dry the primary granules in a fluidized bed dryer at 85°C for 1.5 hours to remove surface moisture; then place the dried primary granules in a hot air circulation oven at 105°C for a second drying for 3.5 hours, controlling the moisture content to ≤0.05%; finally, sieve the secondary dried granules to obtain a nylon composite material.

[0058] Example 2

[0059] Preparation of composite functional intermediate 1:

[0060] Weigh 10 parts of sulfonated polybenzimidazole, 5 parts of montmorillonite, and 1 part of γ-aminopropyltriethoxysilane by weight.

[0061] The montmorillonite was added into a hydrochloric acid solution with a mass fraction of 5%, stirred at a temperature of 60° C. for 4 hours, filtered, washed until neutral, and dried to obtain modified montmorillonite.

[0062] Sulfonated polybenzimidazole, modified montmorillonite and γ-aminopropyltriethoxysilane were added to an ethanol aqueous solution with a volume ratio of ethanol to water of 3:1. The mixture was stirred at a temperature of 50°C and a rotation speed of 300 r / min for 6 hours, and then dried at a temperature of 80°C to constant weight to obtain a composite functional intermediate product 1.

[0063] Preparation of composite functional intermediate 2:

[0064] 15 parts of hydrogenated styrene-butadiene block copolymer, 5 parts of dioctyl adipate, and 2 parts of compatibilizer (maleic anhydride grafted polyethylene) were weighed in parts by weight.

[0065] The hydrogenated styrene-butadiene block copolymer was added to a twin-screw extruder and melted at a temperature of 180°C and a screw speed of 150 r / min. Then, dioctyl adipate and a compatibilizer were added through a side feed port, and the mixture was melt-blended for 5 minutes before extrusion.

[0066] The extrudate was cooled, granulated, and dried at 70° C. for 5 h to obtain a composite functional intermediate product II.

[0067] Preparation of composite functional intermediate three:

[0068] Weigh 5 parts of nano zinc oxide, 2 parts of graphene, and 1 part of polydopamine by weight.

[0069] The graphene was dispersed in deionized water and ultrasonically treated for 30 min to obtain a graphene dispersion.

[0070] Nano-zinc oxide was added to the graphene dispersion, and after stirring evenly, polydopamine was added and reacted at a temperature of 30° C. and a rotation speed of 200 r / min for 8 h.

[0071] The reaction product was centrifuged, washed alternately with deionized water and ethanol three times, and vacuum dried at 60° C. for 24 h to obtain a composite functional intermediate product three.

[0072] Preparation of nylon composite materials:

[0073] Raw material preparation: 50 parts of nylon resin (nylon 6), 10 parts of reinforcing agent (carbon fiber, length 3mm), 5 parts of toughening agent (maleic anhydride grafted polypropylene), 5 parts of flame retardant (aluminum hydroxide), 0.5 parts of lubricant (zinc stearate), 0.1 parts of antioxidant (phosphite antioxidant 168), 3 parts of the above-prepared composite functional intermediate product 1, 2 parts of inorganic filler (talc powder), 4 parts of composite functional intermediate product 2, and 2 parts of composite functional intermediate product 3.

[0074] A method for preparing a nylon composite material, comprising the following steps:

[0075] S1. Pretreatment: Dry the nylon resin in a vacuum drying oven at 100°C for 12 hours; place the reinforcing agent in a plasma treatment device and perform surface treatment at a power of 50W and a treatment time of 15 minutes; add the inorganic filler to a 1% by mass silane coupling agent ethanol solution, stir, and then remove and dry to complete the surface modification.

[0076] S2. Mixing: First, add the pretreated nylon resin, toughening agent, and flame retardant into a high-speed mixer, and perform the first high-speed mixing at a speed of 600 r / min for 3 minutes; then add the lubricant and antioxidant, and perform the second high-speed mixing at a speed of 800 r / min for 2 minutes; finally, add the composite functional intermediate product 1, the pretreated inorganic filler, the composite functional intermediate product 2, and the composite functional intermediate product 3, and perform the third high-speed mixing at a speed of 1000 r / min for 5 minutes to obtain a premix.

[0077] S3. Extrusion: Add the premix to the main feed port of a twin-screw extruder. Set the temperatures in each section of the twin-screw extruder to: 200°C for the feed section, 220°C for the compression section, 240°C for the melt section, and 230°C for the homogenization section. Add the pretreated reinforcing agent to the twin-screw extruder through the side feed port, controlling the ratio of the side feed rate to the main feed rate to be 1:3. The screw speed is controlled at 200 r / min. During the extrusion process, the melt viscosity is monitored in real time using an online viscometer. When the viscosity deviates from the set range (1000-3000 Pa·s), the screw speed is adjusted by ±10 r / min to correct it. The extrudate is water-cooled to room temperature and then pelletized to obtain primary pellets.

[0078] S4. Drying and sieving: Dry the primary granules in a fluidized bed dryer at 80°C for 2 hours to remove surface moisture; then place the dried primary granules in a hot air circulation oven and perform secondary drying at 100°C for 4 hours, controlling the moisture content to ≤0.05%; finally, sieve the secondary dried granules to obtain a nylon composite material.

[0079] Example 3

[0080] Preparation of composite functional intermediate 1:

[0081] 20 parts of sulfonated polybenzimidazole, 15 parts of montmorillonite and 5 parts of γ-aminopropyltriethoxysilane were weighed in parts by weight.

[0082] The montmorillonite was added into a hydrochloric acid solution with a mass fraction of 10%, stirred at a temperature of 80° C. for 2 hours, filtered, washed until neutral, and dried to obtain modified montmorillonite.

[0083] Sulfonated polybenzimidazole, modified montmorillonite and γ-aminopropyltriethoxysilane were added to an ethanol aqueous solution with a volume ratio of ethanol to water of 5:1. The mixture was stirred at 70°C and 500 r / min for 3 hours, and then dried at 100°C to constant weight to obtain a composite functional intermediate product 1.

[0084] Preparation of composite functional intermediate 2:

[0085] 30 parts of hydrogenated styrene-butadiene block copolymer, 15 parts of dioctyl adipate, and 8 parts of a compatibilizer (maleic anhydride grafted styrene-ethylene-butylene-styrene block copolymer) were weighed in parts by weight.

[0086] The hydrogenated styrene-butadiene block copolymer was added to a twin-screw extruder and melted at a temperature of 220°C and a screw speed of 250 r / min. Then, dioctyl adipate and a compatibilizer were added through a side feed port, and the mixture was melt-blended for 10 minutes before extrusion.

[0087] The extrudate was cooled, granulated, and dried at 90° C. for 3 h to obtain a composite functional intermediate product II.

[0088] Preparation of composite functional intermediate three:

[0089] Weigh 12 parts of nano zinc oxide, 6 parts of graphene, and 4 parts of polydopamine by weight.

[0090] The graphene was dispersed in deionized water and ultrasonically treated for 60 min to obtain a graphene dispersion.

[0091] Nano-zinc oxide was added to the graphene dispersion, and after stirring evenly, polydopamine was added and reacted at a temperature of 50° C. and a rotation speed of 400 r / min for 4 hours.

[0092] The reaction product was centrifuged, washed alternately with deionized water and ethanol five times, and vacuum dried at 80° C. for 12 h to obtain a composite functional intermediate product three.

[0093] Preparation of nylon composite materials:

[0094] Raw material preparation: 80 parts of nylon resin (nylon 12), 30 parts of reinforcing agent (basalt fiber, length 10 mm), 15 parts of toughening agent (ethylene-vinyl acetate copolymer), 20 parts of flame retardant (ammonium polyphosphate), 3 parts of lubricant (ethylene bisstearamide), 2 parts of antioxidant (hindered phenol antioxidant 1010 and phosphite antioxidant 168 compounded, mass ratio 1:1), 8 parts of the above-prepared composite functional intermediate product 1, 10 parts of inorganic filler (barium sulfate), 15 parts of composite functional intermediate product 2, and 6 parts of composite functional intermediate product 3.

[0095] A method for preparing a nylon composite material, comprising the following steps:

[0096] S1. Pretreatment: Dry the nylon resin in a vacuum drying oven at 120°C for 8 hours; place the reinforcing agent in a plasma treatment device and perform surface treatment under the conditions of a power of 100 W and a treatment time of 5 minutes; add the inorganic filler to a 3% by mass silane coupling agent ethanol solution and stir, then remove and dry to complete the surface modification.

[0097] S2. Mixing: First, add the pretreated nylon resin, toughening agent, and flame retardant into a high-speed mixer, and perform the first high-speed mixing at a speed of 800 r / min for 2 minutes; then add the lubricant and antioxidant, and perform the second high-speed mixing at a speed of 1000 r / min for 1 minute; finally, add the composite functional intermediate product 1, the pretreated inorganic filler, the composite functional intermediate product 2, and the composite functional intermediate product 3, and perform the third high-speed mixing at a speed of 1200 r / min for 3 minutes to obtain a premix.

[0098] S3. Extrusion: Add the premix to the main feed port of a twin-screw extruder. Set the temperatures in each section of the twin-screw extruder to 220°C for the feed section, 240°C for the compression section, 260°C for the melt section, and 250°C for the homogenization section. Add the pretreated reinforcing agent to the twin-screw extruder through the side feed port, controlling the ratio of the side feed rate to the main feed rate to be 1:5. The screw speed is controlled at 300 r / min. During the extrusion process, the melt viscosity is monitored in real time using an online viscometer. When the viscosity deviates from the set range (1000-3000 Pa·s), the screw speed is adjusted by ±10 r / min to correct it. The extrudate is water-cooled to room temperature and then pelletized to obtain primary pellets.

[0099] S4. Drying and screening: Dry the primary granules in a fluidized bed dryer at 90°C for 1 hour to remove surface moisture; then place the dried primary granules in a hot air circulation oven at 110°C for a second drying for 3 hours, controlling the moisture content to ≤0.05%; finally, screen the secondary dried granules to obtain a nylon composite material.

[0100] Comparative Example 1

[0101] Compared with Example 1, Comparative Example 1 replaces the composite functional intermediate product 1 in Comparative Example 1 with a common acid-resistant additive benzimidazole-pyrimidine copolymer, and no composite functional intermediate product 2 is added. Other raw materials and preparation methods are the same as those in Example 1 to prepare a nylon composite material.

[0102] Comparative Example 2

[0103] Compared with Example 1, Comparative Example 2 lacks the composite functional intermediate product 2. Other raw materials and preparation methods are the same as those in Example 1, and a nylon composite material is prepared.

[0104] Comparative Example 3

[0105] Compared with Example 1, Comparative Example 2 lacks the composite functional intermediate product 3. Other raw materials and preparation methods are the same as those in Example 1, and a nylon composite material is prepared.

[0106] Performance testing:

[0107] Experiments were conducted on the nylon composite materials prepared in Examples 1 to 3 and Comparative Examples 1 to 3. The experimental data are shown in Table 1. The test methods used during the experiments are as follows:

[0108] 1. Mass loss rate test method

[0109] A. Cut uniform-sized specimens (e.g., length × width × thickness = 50 mm × 10 mm × 2 mm) from the modified nylon material, with at least three parallel specimens per group, ensuring that there are no surface defects such as bubbles and cracks. Weigh the initial mass of each specimen (denoted as m0) using an electronic balance with an accuracy of 0.1 mg and record the data.

[0110] B. Prepare a 5% sulfuric acid solution by mass: Accurately measure 50g of concentrated sulfuric acid (98%) and slowly add it to 950g of deionized water. Stir well and let it stand to room temperature. Completely immerse the sample in the above sulfuric acid solution. Seal the container and place it in a constant temperature water bath at (25±2)°C. Set the immersion time according to actual needs (such as 1000h commonly used in the industry, or adjust it according to the material application scenario). During the immersion process, regularly replenish evaporated water to maintain a stable solution concentration.

[0111] C. After the set time is reached, take out the sample and repeatedly rinse the acid remaining on the surface with deionized water until the pH value of the rinse liquid is close to neutral (test with pH paper or acidity meter).

[0112] The sample was placed in a vacuum drying oven at (60±5)°C and dried to constant weight (the difference in mass between two weighings was ≤0.2 mg). After cooling to room temperature, its mass was weighed (recorded as m1).

[0113] D. Calculate the mass loss rate

[0114] formula:

[0115] The average value of the parallel samples is taken as the final result, and the relative deviation is required to be ≤5%.

[0116] 2. Tensile strength retention rate test method

[0117] Prepare standard tensile specimens (such as Type I dumbbell specimens) in accordance with GB / T1040.1-2018 "Determination of Tensile Properties of Plastics Part 1: General Principles" or ASTM D638, with at least 5 parallel specimens per group.

[0118] A. Comparison group settings

[0119] Non-immersion control group: The tensile strength test was performed directly on the specimens that had not been immersed in the acidic solution, and the initial tensile strength (denoted as σ1) was recorded.

[0120] Immersion test group: another group of samples of the same specifications were immersed in 5% sulfuric acid solution for the same time according to the above-mentioned "acidic environment immersion treatment" steps, and then washed and dried, and then subjected to tensile strength test (denoted as σ2).

[0121] B. Use a universal material testing machine, set the tensile speed to 50 mm / min (can be adjusted to 20-100 mm / min according to the characteristics of nylon material), clamp both ends of the specimen, ensure that the axis is consistent with the tensile direction, and avoid eccentric force.

[0122] Record the maximum load at which each specimen breaks and calculate the tensile strength based on the cross-sectional area of ​​the specimen:

[0123]

[0124] Calculate the tensile strength retention:

[0125] The average value of the parallel samples is taken as the final result, and the relative deviation is required to be ≤3%.

[0126] 3. Impact strength retention test after 50 cycles of -40℃ freezing to room temperature.

[0127] A. Sample preparation

[0128] Prepare specimens according to impact test standards (such as GB / T 1043.1-2008 "Determination of Impact Properties of Plastics with Simple Support Beams" or ASTM D256). It is recommended to use simply supported beam notched specimens (notch type A or B, selected according to material properties, thickness is usually 4mm or 10mm).

[0129] Prepare at least 20 parallel samples for each group of samples (including "nylon materials with added composite intermediates" and "blank control materials without additions") to ensure that there are no bubbles on the surface and no burrs on the notches (the notches need to be processed using a special notch sample making machine, and the depth and angle must meet the standards); before testing, place all samples in an environment of (23±2)℃ and relative humidity of (50±5)% for more than 24 hours to eliminate the impact of processing stress on performance.

[0130] B. Freezing-room temperature cycle treatment process

[0131] Freezing stage: Place the sample in a low-temperature test chamber, set the temperature to -40℃±1℃, and maintain it for 3 hours (make sure the center temperature of the sample reaches -40℃, which can be monitored by pre-buried thermocouples).

[0132] Room temperature recovery stage: quickly remove the frozen sample and place it in an environment of (23±2)℃ and relative humidity of (50±5)% for 3 hours (to ensure that the sample is completely restored to room temperature to avoid residual low temperature affecting subsequent tests).

[0133] Number of cycles: Repeat the above process of "freezing for 3 hours → recovering at room temperature for 3 hours" for a total of 50 cycles.

[0134] Avoid violent collisions each time the sample is transferred to prevent damage to the sample due to low-temperature brittleness.

[0135] The specimens in the low-temperature test chamber must be placed in a dispersed manner to avoid stacking, ensuring that each specimen can be cooled evenly.

[0136] When the room temperature returns to normal, a breathable support can be placed under the sample to avoid direct contact with the tabletop, which may cause local temperature unevenness.

[0137] C. Impact strength test

[0138] Initial impact strength test (σ0)

[0139] Five samples were randomly selected from the pre-treated samples and their impact strength (unit: kJ / m 2 ), and take the average value as the “initial impact strength before cycle”.

[0140] Impact strength test after cycle (σ1)

[0141] After 50 cycles, randomly select 5 samples from each group (must be consistent with the specifications of the initial test samples) and immediately test their impact strength under the same environmental conditions (23±2℃, relative humidity 50±5%). The average value is taken as the "impact strength after cycle".

[0142] D. Calculation of impact strength retention rate

[0143] formula:

[0144] 4. Tensile strength retention rate experiment in 120℃ thermal oxidation aging test.

[0145] A. Prepare tensile specimens of nylon material with added composite intermediates and traditional materials (according to GB / T1040.2-2006 standard, using type I or type II specimens), with at least 5 parallel specimens in each group.

[0146] B. Test the initial tensile strength (σ0) of the two groups of materials and take the average value.

[0147] C. Place the sample in a thermal oxygen aging test chamber, set the temperature to 120°C, and introduce compressed air (flow rate 5-10L / h). The aging time is determined according to the stability of the material (usually 1000h or until the performance of traditional materials is significantly reduced).

[0148] D. After aging, take out the sample and place it in a (23±2)℃ environment for 24 hours, and test the tensile strength (σ1).

[0149] Calculate retention rate:

[0150] 5. Tensile strength and fluctuation range test in the range of -40℃ to 80℃

[0151] Using a wide temperature range tensile test:

[0152] According to GB / T 1040 (Plastic Tensile Properties Test Standard) or ASTM D638, a universal testing machine with a temperature control device is used to conduct tensile tests on the material at different temperatures such as -40°C, room temperature (23°C), and 80°C to measure the tensile strength at each temperature.

[0153] Calculate the difference between the tensile strength at different temperatures and the strength at room temperature, calculate the fluctuation range (usually expressed as "maximum difference / room temperature strength × 100%), and verify whether it is controlled within 5%.

[0154] Table 1:

[0155]

[0156] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0157] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A nylon composite material, characterized in that: The raw materials for preparing the nylon composite material include, by weight: 50-80 parts of nylon resin, 10-30 parts of reinforcing agent, 5-15 parts of toughening agent, 5-20 parts of flame retardant, 0.5-3 parts of lubricant, 0.1-2 parts of antioxidant, 3-8 parts of composite functional intermediate product 1, 2-10 parts of inorganic filler, 4-15 parts of composite functional intermediate product 2, and 2-6 parts of composite functional intermediate product 3; the raw materials for preparing the composite functional intermediate product 1 include, by weight: : 10-20 parts of sulfonated polybenzimidazole, 5-15 parts of montmorillonite, and 1-5 parts of γ-aminopropyltriethoxysilane; the raw materials for preparing the composite functional intermediate product II include, by weight: 15-30 parts of hydrogenated styrene-butadiene block copolymer, 5-15 parts of dioctyl adipate, and 2-8 parts of a compatibilizer; the raw materials for preparing the composite functional intermediate product III include, by weight: 5-12 parts of nano zinc oxide, 2-6 parts of graphene, and 1-4 parts of polydopamine.

2. A nylon composite material according to claim 1, characterized in that: The nylon resin is at least one of nylon 6, nylon 66, nylon 11, and nylon 12; the reinforcing agent is at least one of glass fiber, carbon fiber, and basalt fiber, and the length of the reinforcing agent is 3-10 mm; the toughening agent is at least one of maleic anhydride grafted ethylene-octene copolymer, maleic anhydride grafted polypropylene, and ethylene-vinyl acetate copolymer; the flame retardant is a halogen-free flame retardant selected from at least one of magnesium hydroxide, aluminum hydroxide, and ammonium polyphosphate; the lubricant is at least one of calcium stearate, zinc stearate, and ethylene bisstearamide; and the antioxidant is at least one of hindered phenol antioxidants and phosphite antioxidants.

3. The nylon composite material according to claim 1, characterized in that: The preparation method of the composite functional intermediate product 1 comprises the following steps: A1. Weigh sulfonated polybenzimidazole, montmorillonite, and γ-aminopropyltriethoxysilane in parts by weight; A2. Add montmorillonite to a 5-10% by mass hydrochloric acid solution, stir at 60-80°C for 2-4 hours, filter, wash until neutral, and dry to obtain modified montmorillonite; A3. Add sulfonated polybenzimidazole, modified montmorillonite and γ-aminopropyltriethoxysilane to an ethanol aqueous solution, wherein the volume ratio of ethanol to water is 3:1-5:1, stir at a temperature of 50-70°C and a rotation speed of 300-500 r / min for 3-6 hours, and then dry at a temperature of 80-100°C to constant weight to obtain a composite functional intermediate product 1.

4. The nylon composite material according to claim 1, characterized in that: The preparation method of the composite functional intermediate product 2 comprises the following steps: B1. Weigh hydrogenated styrene-butadiene block copolymer, dioctyl adipate and compatibilizer in parts by weight; B2. Add hydrogenated styrene-butadiene block copolymer into a twin-screw extruder and melt it at a temperature of 180-220° C. and a screw speed of 150-250 r / min. Then, add dioctyl adipate and a compatibilizer through a side feed port, continue melt blending for 5-10 minutes, and then extrude. B3. Cool the extrudate, granulate it, and dry it at a temperature of 70-90° C. for 3-5 hours to obtain a composite functional intermediate product II.

5. The nylon composite material according to claim 4, characterized in that: The compatibilizer is at least one of maleic anhydride grafted styrene-ethylene-butylene-styrene block copolymer and maleic anhydride grafted polyethylene.

6. The nylon composite material according to claim 1, characterized in that: The preparation method of the composite functional intermediate product three comprises the following steps: C1. Weigh nano zinc oxide, graphene and polydopamine by weight; C2. Dispersing the graphene in deionized water and ultrasonically treating for 30-60 min to obtain a graphene dispersion; C3. Add nano zinc oxide to the graphene dispersion, stir evenly, then add polydopamine, and react at a temperature of 30-50°C and a rotation speed of 200-400 r / min for 4-8 hours; C4. The reaction product is centrifuged, washed alternately with deionized water and ethanol for 3-5 times, and vacuum dried at a temperature of 60-80° C. for 12-24 hours to obtain a composite functional intermediate product three; the particle size of the nano zinc oxide is 20-50 nm; the graphene is obtained by reducing graphene oxide, and the flake diameter is 0.5-2 μm.

7. A method for preparing a nylon composite material according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: S1. Place the nylon resin in a vacuum drying oven to remove moisture; place the reinforcing agent in a plasma treatment device for surface treatment to enhance its bonding with the substrate; add the inorganic filler to a 1-3% by mass silane coupling agent ethanol solution, stir, and then remove and dry to complete the surface modification; S2, first add the pretreated nylon resin, toughening agent, and flame retardant into a high-speed mixer for a first high-speed mixing; then add the lubricant and antioxidant for a second high-speed mixing; finally, add the composite functional intermediate product 1, the pretreated inorganic filler, the composite functional intermediate product 2, and the composite functional intermediate product 3, and perform a third high-speed mixing to obtain a premix; S3. Add the premix to the main feed port of a twin-screw extruder and set the temperature of each section of the twin-screw extruder; add the pretreated reinforcing agent to the twin-screw extruder through the side feed port, and control the ratio of the side feed rate to the main feed rate to be 1:(3-5); control the screw speed to be 200-300 r / min; during the extrusion process, monitor the melt viscosity in real time using an online viscometer; when the viscosity deviates from the set range (1000-3000 Pa·s), adjust the screw speed by ±10 r / min to make corrections; and water-cool the extrudate to room temperature and then pelletize to obtain primary pellets; S4. Dry the primary particles in a fluidized bed drying machine to remove surface moisture; then place the dried primary particles in a hot air circulation oven for a second drying to control the moisture content to ≤0.05%; finally, sieve the particles after the second drying to obtain a nylon composite material.

8. The method for preparing a nylon composite material according to claim 7, characterized in that: In step S1, the nylon resin is dried at 100-120° C. for 8-12 hours; the surface treatment condition of the reinforcing agent is at a power of 50-100 W and a treatment time of 5-15 minutes; in step S2, the first high-speed mixing condition is mixed at a rotation speed of 600-800 r / min for 2-3 minutes; the second high-speed mixing condition is mixed at a rotation speed of 800-1000 r / min for 1-2 minutes; and the third high-speed mixing condition is mixed at a rotation speed of 1000-1200 r / min for 3-5 minutes.

9. The method for preparing a nylon composite material according to claim 7, characterized in that: In step S3, the temperature of each section of the twin-screw extruder is: feeding section 200-220°C, compression section 220-240°C, melting section 240-260°C, and homogenization section 230-250°C; in step S4, the primary drying conditions are: drying at 80-90°C for 1-2 hours; and the secondary drying conditions are: secondary drying at 100-110°C for 3-4 hours.

10. The nylon composite material according to any one of claims 1 to 6, characterized in that: The nylon composite material is used to prepare low-temperature pipe fittings, electronic and electrical appliance housings, and automobile component nylon products.

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