Corrosion-resistant composite material for pin insulator wire fixing device and preparation method thereof

Abstract

The application relates to the technical field of high polymer composite materials, and particularly relates to a corrosion-resistant composite material for a pin-type insulator wire fixing device and a preparation method thereof, which comprises, by weight, 75-85 parts of isotactic polypropylene, 5-10 parts of ethylene-propylene copolymer elastomer, 2-4 parts of maleic anhydride grafted polypropylene, 0.5-1 part of polyethylene glycol, 3-5 parts of nano-silicon dioxide with surface silane treatment, 5-10 parts of surface-modified mica flake, 0.5-2 parts of fluorinated graphene, 0.2-0.5 part of hindered amine light stabilizer, 0.2-0.5 part of hindered phenolic antioxidant, 0.2-0.4 part of benzotriazole ultraviolet absorber, 0.3-0.6 part of metal stearate, and 0.1-0.3 part of beta-crystal nucleating agent, which effectively blocks the penetration of corrosion medium and has excellent corrosion resistance under the corrosion medium in an acidic, alkaline and salt spray environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer composite materials, and particularly relates to a corrosion-resistant composite material for a pin-type insulator wire fixing device and a preparation method thereof. The composite material has excellent corrosion resistance, aging resistance, mechanical properties and electrical insulation properties, and is particularly suitable for pin-type insulator wire fixing devices in power systems and other power equipment components that need to be used for a long time in harsh environments. BACKGROUND

[0002] Pin-type insulator wire fixing devices are important components in power transmission systems. During use, they are exposed to various complex environments for a long time, such as acid rain, alkaline dust, ultraviolet radiation, high temperature and humidity, atmospheric pollutants, etc. They are prone to corrosion and aging, which leads to a decrease in mechanical and electrical properties, and in severe cases, even causes line failure. Therefore, the pin-type insulator wire fixing device material must have excellent corrosion resistance, aging resistance, mechanical properties and electrical insulation properties.

[0003] Traditional pin-type insulator wire fixing devices are mainly made of metal materials or ordinary engineering plastics. U.S. Patent US2500927A discloses a pin-type insulator made of magnesium alloy. Although its corrosion resistance is improved compared with ordinary steel, it is still prone to corrosion in strong corrosive environments such as acid rain. U.S. Patent US5147984A discloses a pin-type insulator composed of a porcelain head and a polymer anti-fouling skirt. This technology mainly focuses on the structural design of the insulator itself, but does not deeply solve the material problem of the wire fixing device. European Patent EP0560939B1 discloses an improved structure of a cap and a pin-type insulator, which uses polyolefin, epoxy resin, etc. as the material of the insulating part, but its corrosion resistance and aging resistance need to be further improved.

[0004] Chinese Patent CN110185851A discloses a high-voltage and high-corrosion-resistant polypropylene composite pipe and a preparation method thereof. The material is composed of a reinforced beta-PPH layer, a fiber layer and a beta-PPH layer in sequence, and is mainly used for pipeline applications. It is not optimized for the special requirements of pin-type insulator wire fixing devices. Chinese Patent CN102827422B discloses a long-term heat-oxidative aging-resistant polypropylene composite and a preparation method thereof. By adding beta nucleating agent, stem grafting aid and antioxidant, etc., the heat-oxidative aging resistance of the material is improved, but the corrosion resistance and electrical properties required by pin-type insulator wire fixing devices are not considered.

[0005] In summary, there is still a lack of a high-performance corrosion-resistant composite material specially designed for the pin-type insulator wire fixing device in the prior art, which needs to meet the requirements of corrosion resistance, aging resistance, mechanical properties and electrical properties and other aspects. Therefore, it is urgent to develop a new type of composite material to solve the material performance problems of the pin-type insulator wire fixing device in the long-term use process. SUMMARY

[0006] The purpose of the present application is to provide a corrosion-resistant composite material for a pin-type insulator wire fixing device and a preparation method thereof, which solves the deficiencies of existing materials in corrosion resistance, aging resistance, mechanical properties and electrical properties, etc. through multi-component synergistic design, multi-scale filler system and interface optimization.

[0007] To achieve the above-mentioned purpose, the present application provides a corrosion-resistant composite material for a pin-type insulator wire fixing device, which comprises, by weight:

[0008] Isotactic polypropylene (iPP) 75-85 parts;

[0009] Ethylene-propylene copolymer elastomer (EPR) 5-10 parts;

[0010] Maleic anhydride grafted polypropylene (PP-g-MA) 2-4 parts;

[0011] Polyethylene glycol (PEG) 0.5-1 part;

[0012] Surface silanization treated nano-silicon dioxide 3-5 parts;

[0013] Surface modified mica flake 5-10 parts;

[0014] Fluorinated graphene 0.5-2 parts;

[0015] Hindered amine light stabilizer (HALS) 0.2-0.5 parts;

[0016] Hindered phenolic antioxidant 0.2-0.5 parts;

[0017] Benzotriazole ultraviolet absorber 0.2-0.4 parts;

[0018] Metal stearate 0.3-0.6 parts;

[0019] Beta crystal nucleating agent 0.1-0.3 parts.

[0020] Specifically, the melt flow rate (MFR, 230℃ / 2.16kg) of the isotactic polypropylene is 2-8g / 10min, and the isotacticity is ≥95%.

[0021] Specifically, the ethylene content in the ethylene-propylene copolymer elastomer is 40-60% by weight, and the Mooney viscosity (ML1+4, 125°C) is 15-40.

[0022] Specifically, the maleic anhydride grafting rate of the maleic anhydride-grafted polypropylene is 0.8-1.5% by weight, and the melt flow rate (MFR, 230℃ / 2.16kg) is 80-120g / 10min.

[0023] Specifically, the average particle size of the nano-silica is 15-30 nm, and the specific surface area is 120-300 m². 2 / g; the average particle size of the surface-modified mica sheets is 10-50μm, and the aspect ratio is 10-50; the fluorinated graphene has a lateral dimension of 0.5-5μm, a thickness of 1-5nm, and a fluorine content of 5%-25%.

[0024] The method for preparing the corrosion-resistant composite material for pin-type insulator wire fixing device includes the following steps:

[0025] (1) Raw material pretreatment;

[0026] (2) Preparation of functional masterbatch;

[0027] (3) Preparation of the main composite material;

[0028] (4) Molding and processing.

[0029] Specifically, step (1) of raw material pretreatment includes:

[0030] a) Polymer pretreatment: isotactic polypropylene (iPP) was vacuum dried at 80±5℃ for 8-12 hours, ethylene-propylene copolymer (EPR) was vacuum dried at 60±5℃ for 6-10 hours, and maleic anhydride grafted polypropylene (PP-g-MA) was vacuum dried at 70±5℃ for 8-12 hours. The moisture content of all polymers after drying was ≤0.05%.

[0031] b) Nano silica surface treatment: After vacuum drying at 110±10℃ for 12-24 hours, disperse in anhydrous ethanol at a concentration of 5-10% by weight, add γ-aminopropyltrimethoxysilane (KH-550) at an amount of 3%-5% by weight of SiO2, stir and react at 50-60℃ for 2-4 hours, adjust the pH to 4-5, filter and wash, and then dry at 80±5℃ for 12-24 hours.

[0032] c) Mica flake surface treatment: after vacuum drying at 110±10℃ for 12-24 hours, dispersing in absolute ethanol with a concentration of 10-20 wt%, adding γ-aminopropyltrimethoxysilane (KH-550) in an amount of 2%-4% of the weight of the mica, stirring and reacting at 50-60℃ for 2-4 hours, adjusting the pH to 4-5, filtering and washing, and then drying at 100±10℃ for 12-24 hours;

[0033] d) Fluorinated graphene pretreatment: after vacuum drying at 70±5℃ for 12-24 hours, ultrasonic dispersion in isopropanol with a concentration of 0.1-0.5 mg / mL, ultrasonic conditions of power 300-500 W, intermittent mode (30 s of work and 10 s of pause), total time 2-4 hours, vacuum drying at 60±5℃ for 12-24 hours after removing the solvent by rotary evaporation;

[0034] e) Additive pretreatment: antioxidant, light stabilizer vacuum drying at 60±5℃ for 4-8 hours, β crystal nucleating agent vacuum drying at 70±5℃ for 6-10 hours, all additives are pulverized to a particle size of ≤100 μm.

[0035] Specifically, the step (2) functional masterbatch preparation includes:

[0036] a) Nano-SiO2 / PP masterbatch preparation: dry mixing of surface-treated nano-SiO2 15-25 wt%, PP-g-MA 10-15 wt%, isotactic PP 60-75 wt% in a high-speed mixer at a speed of 500-800 rpm for 5-10 minutes, then extruding in a co-rotating twin-screw extruder with a temperature distribution of 165-175-185-195-195-190-185℃ and a screw speed of 200-300 rpm, underwater pelletizing, and then hot air drying at 80±5℃ for 4-6 hours;

[0037] b) Mica flake / PP masterbatch preparation: dry mixing of surface-treated mica flake 30-40 wt%, PP-g-MA 8-12 wt%, isotactic PP 48-62 wt% in a high-speed mixer at a speed of 500-800 rpm for 5-10 minutes, then extruding in a co-rotating twin-screw extruder with a temperature distribution of 165-175-185-195-195-190-185℃ and a screw speed of 150-250 rpm, underwater pelletizing, and then hot air drying at 80±5℃ for 4-6 hours;

[0038] c) Fluorinated graphene / PP masterbatch preparation: Fluorinated graphene 3-5 wt%, PP-g-MA 15-20 wt%, isotactic PP 75-82 wt%, first ultrasonic dispersion of fluorinated graphene in a small amount of isopropanol, then mixed with PP-g-MA powder, vacuum dried at 60±5°C for 12-24 hours to remove the solvent, then add isotactic PP and dry mix in a high-speed mixer at 500-800 rpm for 5-10 minutes, extruded in a co-rotating twin-screw extruder with a temperature distribution of 160-170-180-190-190-185-180°C and a screw speed of 250-350 rpm, then underwater pelletized and hot air dried at 80±5°C for 4-6 hours;

[0039] d) Additive masterbatch preparation: Hindered amine light stabilizer 5-10 wt%, hindered phenolic antioxidant 5-10 wt%, benzotriazole ultraviolet absorber 5-10 wt%, metal stearate 5-10 wt%, β crystal nucleating agent 2-5 wt%, isotactic PP 55-80 wt%, dry mixed in a high-speed mixer at 500-800 rpm for 5-10 minutes, extruded in a co-rotating twin-screw extruder with a temperature distribution of 160-170-180-180-175-170°C and a screw speed of 200-300 rpm, then underwater pelletized and hot air dried at 70±5°C for 4-6 hours.

[0040] Specifically, the step (3) bulk composite material preparation includes:

[0041] According to the content of active components in each masterbatch, calculate the amount of each masterbatch required to achieve the target formulation of the final product; dry all components to a moisture content of ≤0.05%; accurately measure each component according to the formulation, dry mix in a high-speed mixer at 400-600 rpm for 5-8 minutes; blend and extrude in a co-rotating twin-screw extruder with an L / D of 36-48, equipped with special mixing and shearing elements, containing multiple shearing and mixing zones, a temperature distribution of 170-180-190-200-200-195-190°C, a screw speed of 200-300 rpm, a production rate controlled at 40-80 kg / h, a residence time of 2-4 minutes, a die pressure controlled at 3-6 MPa, pelletized by an underwater pelletizing system and hot air dried at 80±5°C for 6-8 hours with a moisture content of ≤0.05%, and finally screened to remove abnormal particles.

[0042] Specifically, the step (4) forming process uses injection molding or extrusion molding, wherein:

[0043] The barrel temperature distribution is 170-180-190-200℃, the mold temperature is 20-40℃ or 80-100℃, the injection pressure is 80-120MPa, the holding pressure is 50-80MPa, the holding time is the product wall thickness (mm) x 4 seconds, the cooling time is the product wall thickness (mm) 2 x 2 seconds, the screw rotation speed is 50-100rpm, and the back pressure is 5-10MPa.

[0044] The barrel temperature distribution is 165-175-185-195-190℃, the mold temperature is 180-190℃, the cooling tank temperature is 15-25℃, and the screw rotation speed is 30-60rpm.

[0045] The beneficial effects of the present application are:

[0046] 1. High corrosion resistance: The present application constructs a multi-barrier structure through a multi-scale filler system (nano-silica, fluorinated graphene and mica plate), effectively blocking the penetration of corrosive media, and has excellent corrosion resistance in acidic, alkaline and salt spray environments. After testing, the mechanical property retention rate of the composite material of the present application can reach 93%~96% after soaking in acidic environment (pH=2) for 1000h, the mechanical property retention rate can reach 95%~97% after soaking in alkaline environment (pH=12) for 1000h, and the surface state has no obvious change after exposure in salt spray environment (5% NaCl) for 1000h.

[0047] 2. Excellent aging resistance: The present application realizes comprehensive protection against ultraviolet aging and thermal-oxidative aging through a triple synergistic protection system of hindered amine light stabilizer (HALS), hindered phenolic antioxidant and benzotriazole ultraviolet absorber. After testing, the mechanical property retention rate of the composite material of the present application is 88%~95% after UV aging for 2000h, the mechanical property retention rate is 90%~93% after thermal aging (120℃) for 1000h, and the mechanical property retention rate can reach 88% after 100 cycles of thermal-humidity aging.

[0048] 3. Excellent mechanical property balance: The present application toughens through ethylene-propylene copolymer elastomer (EPR) and regulates the crystalline structure through β-crystal nucleating agent, which significantly improves the toughness and impact resistance of the material while maintaining high strength. After testing, the tensile strength of the composite material of the present application can reach 30-34MPa, the elongation at break can reach 180%~230%, the flexural modulus can reach 1320-1450MPa, and the low-temperature impact strength at-20℃ can reach 12-18kJ / m 2 , which meets the stringent use requirements of needle insulator wire fixing device.

[0049] 4. Excellent electrical performance: the present application enables the composite material to have excellent electrical insulation performance by optimizing the formulation and processing technology, with volume resistivity reaching 2-3*101 6 Ω·cm, dielectric strength reaching 28-30kV / mm, fully meeting the insulation requirements of power systems.

[0050] 5. Innovative processing technology: the present application adopts a three-stage process of pre-dispersion-masterbatch-main body blending, realizing good dispersion of nanofillers, solving the problem of easy agglomeration of nanofillers in traditional processes, and significantly improving the performance stability and consistency of the product.

[0051] In summary, the corrosion-resistant composite material for the wire fixing device of the pin-type insulator provided by the present application realizes the comprehensive improvement of corrosion resistance, aging resistance, mechanical properties and electrical properties through multi-component synergistic design, multi-scale filler system and interface optimization, and provides an ideal material solution for the wire fixing device of the pin-type insulator. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 Figure 1 is a structural characterization diagram of fluorinated graphene of the present application, Figure 1 (A) is the XRD pattern of fluorinated graphene, and the characteristic peak at 2θ = 10.5° corresponds to the (001) crystal face, which is obviously left-shifted compared with the 2θ = 26.5° of ordinary graphene, indicating that the introduction of fluorine atoms increases the interlayer spacing. Figure 1 (B) is the SEM image of fluorinated graphene, showing a typical two-dimensional sheet structure, with a lateral size in the range of 0.5-5μm, which is consistent with the size of the material used in the present application. Figure 1 (C) is the high-resolution TEM image of fluorinated graphene, which can observe the wrinkle structure on its surface and a few layered stacking areas, with a layer number of about 3-5 layers and a thickness in the range of 1-5nm, verifying the nanoscale characteristics of the material.

[0053] Figure 2 (A) torque-time curve and (B) temperature-time curve of the mixing process of different formulations in a twin-screw extruder, and curves a, b, c and d correspond to Example 1, Example 2, Example 3 and Example 4 respectively. It can be observed that the torque value of the formulation containing fluorinated graphene (b, c, d) is slightly higher than that of the formulation without fluorinated graphene (a) in the initial mixing stage (2-3 minutes), indicating that the addition of fluorinated graphene increases the viscosity of the system in the initial stage. However, in the later mixing stage (5-10 minutes), the torque curve tends to be stable, indicating that the components have reached good dispersion. Figure 2 (B) shows that the temperature curve of all formulations remains stable during the mixing process, with a fluctuation range within ±5℃, which is crucial for ensuring the stability of the material and preventing degradation.

[0054] Figure 3SEM images of the fracture surfaces of Comparative Examples 1 (A, C) and Example 2 (B, D) were observed at magnifications of ×2000 (A, B) and ×10000 (C, D), respectively. The comparison shows that the cross-sections of Comparative Example 1 (A, C) without fluorinated graphene are relatively smooth, with uneven filler dispersion and obvious agglomeration (as shown by the white arrow in C). In contrast, the cross-sections of Example 2 (B, D) containing fluorinated graphene exhibit more ductile fracture characteristics, with more uniform filler dispersion. In the high-magnification image (D), good dispersion of sheet-like fluorinated graphene (indicated by the red arrow) and nano-silica (indicated by the yellow arrow) can be observed. These microstructural observations directly confirm the improving effect of fluorinated graphene on filler dispersion and interfacial compatibility, as well as the microscopic mechanism by which it enhances material toughness. Detailed Implementation

[0055] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0056] The main raw materials used in this invention are as follows:

[0057] 1) Isotactic polypropylene (iPP): Melt flow rate (MFR, 230℃ / 2.16kg) is 2-8 g / 10min, and density is 0.90-0.92 g / cm³. 3 It has a melting point of 160-170℃, isotacticity ≥95%, and is supplied by ExxonMobil under the trade name PPH1500.

[0058] 2) Ethylene-propylene copolymer elastomer (EPR): Ethylene content 40-60% by weight, Mooney viscosity (ML1+4, 125℃) 15-40, density 0.85-0.88 g / cm³ 3 Supplied by Dow Chemical Company, trade name NORDEL TM IP 4520.

[0059] 3) Maleic anhydride-grafted polypropylene (PP-g-MA): Melt flow rate (MFR, 230℃ / 2.16kg) is 80-120g / 10min, maleic anhydride grafting rate is 0.8-1.5% by weight, melting point is 150-165℃, supplied by DuPont, trade name: P353.

[0060] 4) Polyethylene glycol (PEG): Molecular weight (Mn) 4000, melting point 58-62℃, supplied by BASF, trade name: E 4000.

[0061] 5) Nano-silica: Average particle size is 15-30 nm, and specific surface area is 120-300 m². 2 / g, purity ≥ 99.5%, provided by the Win Creation Industrial Group, trade name 200.

[0062] 6) Mica flakes: average particle size 10-50 μm, thickness 0.1-1 μm, aspect ratio 10-50.

[0063] 7) Fluorinated graphene: lateral size 0.5-5 μm, thickness 1-5 nm, fluorine content 5%-25%, carbon content ≥ 99%.

[0064] 8) Hindered amine light stabilizer (HALS): molecular weight 2500-3000, melting point 80-85 °C, provided by the BASF Company, trade name 770.

[0065] 9) Hindered phenolic antioxidant: melting point 165-170 °C, molecular weight 530-550, provided by the BASF Company, trade name 1010.

[0066] 10) Benzotriazole ultraviolet absorber: melting point 125-130 °C, molecular weight 315-325, provided by the BASF Company, trade name 326.

[0067] 11) Metal stearate: melting point 115-120 °C, provided by the Han Qu Company, trade name CA502.

[0068] 12) β-crystal nucleating agent: melting point 240-245 °C, provided by the Milliken Company, trade name NX8000.

[0069] 13) γ-aminopropyltrimethoxysilane (KH-550): boiling point > 100 °C, purity ≥ 98%, provided by the Bayer Company, trade name AMMO.

[0070] 14) Anhydrous ethanol: purity ≥ 99.5%.

[0071] 15) Isopropyl alcohol: purity ≥ 99.5%.

[0072] Example 1: Basic corrosion-resistant polypropylene composite

[0073] The embodiment provides a basic type of corrosion-resistant polypropylene composite material, which comprises, in parts by weight, the following components: 80 parts of isotactic polypropylene (iPP); 7 parts of ethylene-propylene copolymer elastomer (EPR); 3 parts of maleic anhydride grafted polypropylene (PP-g-MA); 0.5 parts of polyethylene glycol (PEG); 4 parts of surface silane-treated nano-silicon dioxide; 4 parts of surface-modified mica flake; 0.3 parts of hindered amine light stabilizer (HALS); 0.3 parts of hindered phenolic antioxidant; 0.3 parts of benzotriazole ultraviolet absorber; 0.4 parts of metal stearate; and 0.2 parts of beta crystal nucleating agent.

[0074] The preparation method of the composite material comprises the following steps:

[0075] (1) Raw material pretreatment

[0076] Firstly, the polymer material is subjected to drying treatment. Isotactic polypropylene (iPP, MFR=4 g / 10 min) is vacuum dried at 80 DEG C for 10 hours, and the moisture content is controlled to be less than 0.05%; ethylene-propylene copolymer elastomer (EPR, ethylene content 50%) is vacuum dried at 60 DEG C for 8 hours, and the moisture content is controlled to be less than 0.05%; and maleic anhydride grafted polypropylene (PP-g-MA, grafting rate 1.2%) is vacuum dried at 70 DEG C for 10 hours, and the moisture content is controlled to be less than 0.05%.

[0077] Secondly, the fillers are subjected to surface treatment. Nano-silicon dioxide (average particle size 20 nm) is vacuum dried at 110 DEG C for 18 hours, then dispersed in anhydrous ethanol at a concentration of 8% by weight, then gamma-aminopropyltrimethoxysilane (KH-550) is added in an amount of 4% of the weight of SiO2, and stirring reaction is carried out at 55 DEG C for 3 hours, the pH value is adjusted to 4.5, and after filtration and washing, drying is carried out at 80 DEG C for 18 hours. Mica flake (average particle size 30 mu m) is vacuum dried at 110 DEG C for 18 hours, then dispersed in anhydrous ethanol at a concentration of 15% by weight, then gamma-aminopropyltrimethoxysilane (KH-550) is added in an amount of 3% of the weight of mica, and stirring reaction is carried out at 55 DEG C for 3 hours, the pH value is adjusted to 4.5, and after filtration and washing, drying is carried out at 100 DEG C for 18 hours.

[0078] Finally, the additives are pretreated. The hindered amine light stabilizer (HALS) and the hindered phenolic antioxidant are vacuum dried at 60 DEG C for 6 hours, the beta crystal nucleating agent is vacuum dried at 70 DEG C for 8 hours, and all the additives are crushed to a particle size of less than 100 mu m.

[0079] (2) Preparation of functional masterbatch

[0080] First, nano-SiO2 / PP masterbatch was prepared. 20% by weight of surface-treated nano-SiO2, 12% by weight of PP-g-MA, and 68% by weight of isotactic PP were dry-mixed in a high-speed mixer at 650 rpm for 8 minutes. Then, the mixture was extruded in a co-rotating twin-screw extruder (L / D = 36) at a temperature distribution of 165-175-185-195-195-190-185℃ and a screw speed of 250 rpm. After underwater pelletizing, the mixture was hot-air dried at 80℃ for 5 hours.

[0081] Next, mica sheets / PP masterbatch were prepared. 35% by weight of surface-treated mica sheets, 10% by weight of PP-g-MA, and 55% by weight of isotactic PP were dry-mixed in a high-speed mixer at 650 rpm for 8 minutes. Then, the mixture was extruded in a co-rotating twin-screw extruder (L / D = 36) at a temperature distribution of 165-175-185-195-195-190-185℃ and a screw speed of 200 rpm. After underwater pelletizing, the mixture was hot-air dried at 80℃ for 5 hours.

[0082] Finally, the auxiliary masterbatch was prepared. 7.5 wt% hindered amine light stabilizer, 7.5 wt% hindered phenolic antioxidant, 7.5 wt% benzotriazole UV absorber, 7.5 wt% metal stearate, 3.5 wt% β-crystal nucleating agent, and 66.5 wt% isotactic PP were dry-mixed in a high-speed mixer at 650 rpm for 8 minutes. Then, the mixture was extruded in a co-rotating twin-screw extruder (L / D = 32) at a temperature distribution of 160-170-180-180-175-170℃ and a screw speed of 250 rpm. After underwater pelletizing, the mixture was hot-air dried at 70℃ for 5 hours.

[0083] (3) Preparation of main composite materials

[0084] Based on the active component content of each masterbatch, calculate the required amount of each masterbatch to achieve the target formulation of the final product. Dry all components to a moisture content ≤0.05%, then accurately measure each component according to the formulation and dry-mix in a high-speed mixer at 500 rpm for 7 minutes. Next, co-extrude in a co-rotating twin-screw extruder (L / D=40). This extruder is equipped with special mixing and shearing elements, including two shearing zones and three mixing zones, with a temperature distribution of 170-180-190-200-200-195-190℃, a screw speed of 250 rpm, a production rate controlled at 60 kg / h, a residence time of 3 minutes, and a die pressure controlled at 4.5 MPa. Finally, after granulation by an underwater pelletizing system, dry in hot air at 80℃ for 7 hours to a moisture content ≤0.05%, then sieve to remove abnormal particles.

[0085] (4) Molding and processing

[0086] Test samples were prepared using injection molding. The barrel temperature of the injection molding machine was 170-180-190-200℃, the mold temperature was 30℃, the injection pressure was 100MPa, the holding pressure was 65MPa, the holding time and cooling time were adjusted according to the wall thickness of the product, the screw speed was 75rpm, and the back pressure was 7.5MPa.

[0087] The performance test results of the composite material are as follows: tensile strength is 33 MPa, elongation at break is 170%, flexural modulus is 1420 MPa, and notched impact strength at -20℃ is 11 kJ / m. 2 After immersion in an acidic environment (pH=2) for 1000 hours, the mechanical properties retained 87%; after immersion in an alkaline environment (pH=12) for 1000 hours, the mechanical properties retained 89%; after UV aging for 2000 hours, the mechanical properties retained 82%; and the volume resistivity was 2.2 × 10⁻⁶. 16 Ω·cm, dielectric strength is 28kV / mm.

[0088] Example 2: High corrosion-resistant polypropylene composite material

[0089] This embodiment provides a highly corrosion-resistant polypropylene composite material, comprising, by weight: 78 parts isotactic polypropylene (iPP); 8 parts ethylene-propylene copolymer elastomer (EPR); 3 parts maleic anhydride-grafted polypropylene (PP-g-MA); 0.5 parts polyethylene glycol (PEG); 3 parts surface-silanized nano-silica; 6 parts surface-modified mica sheets; 1 part fluorinated graphene; 0.3 parts hindered amine light stabilizer (HALS); 0.3 parts hindered phenolic antioxidant; 0.3 parts benzotriazole ultraviolet absorber; 0.4 parts metal stearate; and 0.2 parts β-crystal nucleating agent.

[0090] The preparation method of this composite material includes the following steps:

[0091] (1) Raw material pretreatment

[0092] First, the polymer materials were dried. Isotactic polypropylene (iPP, MFR = 3 g / 10 min) was vacuum dried at 80°C for 10 hours, with the moisture content controlled below 0.05%. Ethylene-propylene copolymer elastomer (EPR, ethylene content 45%) was vacuum dried at 60°C for 8 hours, with the moisture content controlled below 0.05%. Maleic anhydride grafted polypropylene (PP-g-MA, grafting rate 1.0%) was vacuum dried at 70°C for 10 hours, with the moisture content controlled below 0.05%.

[0093] Secondly, the fillers underwent surface treatment. Nano-silica (average particle size 15 nm) was vacuum dried at 110 °C for 18 hours, then dispersed in anhydrous ethanol at a concentration of 8% by weight. γ-aminopropyltrimethoxysilane (KH-550) was then added at 4% of the SiO2 weight, and the mixture was stirred at 55 °C for 3 hours. The pH was adjusted to 4.5, and after filtration and washing, the mixture was dried at 80 °C for 18 hours. Mica flakes (average particle size 25 μm) were vacuum dried at 110 °C for 18 hours, then dispersed in anhydrous ethanol at a concentration of 15% by weight. γ-aminopropyltrimethoxysilane (KH-550) was then added at 3% of the mica weight, and the mixture was stirred at 55 °C for 3 hours. The pH was adjusted to 4.5, and after filtration and washing, the mixture was dried at 100 °C for 18 hours. Fluorinated graphene (2 μm lateral dimension) was vacuum dried at 70 °C for 18 hours, then ultrasonically dispersed in isopropanol at a concentration of 0.3 mg / mL. The ultrasonic conditions were 400 W power, intermittent mode (30 s working, 10 s pause), for a total time of 3 hours. After removing the solvent by rotary evaporation, it was vacuum dried at 60 °C for 18 hours.

[0094] Finally, the additives were pretreated. Hindered amine light stabilizer (HALS) and hindered phenolic antioxidant were vacuum dried at 60°C for 6 hours, β-crystal nucleating agent was vacuum dried at 70°C for 8 hours, and all additives were pulverized to a particle size of less than 100 μm.

[0095] (2) Preparation of functional masterbatch

[0096] First, nano-SiO2 / PP masterbatch was prepared. 20% by weight of surface-treated nano-SiO2, 12% by weight of PP-g-MA, and 68% by weight of isotactic PP were dry-mixed in a high-speed mixer at 650 rpm for 8 minutes. Then, the mixture was extruded in a co-rotating twin-screw extruder (L / D = 36) at a temperature distribution of 165-175-185-195-195-190-185℃ and a screw speed of 250 rpm. After underwater pelletizing, the mixture was hot-air dried at 80℃ for 5 hours.

[0097] Next, mica sheets / PP masterbatch were prepared. 35% by weight of surface-treated mica sheets, 10% by weight of PP-g-MA, and 55% by weight of isotactic PP were dry-mixed in a high-speed mixer at 650 rpm for 8 minutes. Then, the mixture was extruded in a co-rotating twin-screw extruder (L / D = 36) at a temperature distribution of 165-175-185-195-195-190-185℃ and a screw speed of 200 rpm. After underwater pelletizing, the mixture was hot-air dried at 80℃ for 5 hours.

[0098] Next, fluorinated graphene / PP masterbatch was prepared. Fluorinated graphene (4 wt%), PP-g-MA (18 wt%), and isotactic PP (78 wt%) were first ultrasonically dispersed in a small amount of isopropanol and then mixed with PP-g-MA powder. The mixture was vacuum dried at 60°C for 18 hours to remove the solvent. Then, isotactic PP was added and dry-mixed in a high-speed mixer at 650 rpm for 8 minutes. The mixture was then extruded in a co-rotating twin-screw extruder (L / D = 40) at a temperature distribution of 160-170-180-190-190-185-180°C and a screw speed of 300 rpm. After underwater pelletizing, the mixture was hot-air dried at 80°C for 5 hours.

[0099] Finally, the auxiliary masterbatch was prepared. 7.5 wt% hindered amine light stabilizer, 7.5 wt% hindered phenolic antioxidant, 7.5 wt% benzotriazole UV absorber, 7.5 wt% metal stearate, 3.5 wt% β-crystal nucleating agent, and 66.5 wt% isotactic PP were dry-mixed in a high-speed mixer at 650 rpm for 8 minutes. Then, the mixture was extruded in a co-rotating twin-screw extruder (L / D = 32) at a temperature distribution of 160-170-180-180-175-170℃ and a screw speed of 250 rpm. After underwater pelletizing, the mixture was hot-air dried at 70℃ for 5 hours.

[0100] (3) Preparation of main composite materials

[0101] Based on the active component content of each masterbatch, calculate the required amount of each masterbatch to achieve the target formulation of the final product. Dry all components to a moisture content ≤0.05%, then accurately measure each component according to the formulation and dry-mix in a high-speed mixer at 500 rpm for 7 minutes. Next, co-extrude in a co-rotating twin-screw extruder (L / D=40). This extruder is equipped with special mixing and shearing elements, including two shearing zones and three mixing zones, with a temperature distribution of 170-180-190-200-200-195-190℃, a screw speed of 250 rpm, a production rate controlled at 60 kg / h, a residence time of 3 minutes, and a die pressure controlled at 4.5 MPa. Finally, after granulation by an underwater pelletizing system, dry in hot air at 80℃ for 7 hours to a moisture content ≤0.05%, then sieve to remove abnormal particles.

[0102] (4) Molding and processing

[0103] Test samples were prepared using injection molding. The barrel temperature distribution of the injection molding machine was 170-180-190-200℃, the mold temperature was 90℃ (to promote β-crystal formation), the injection pressure was 100MPa, the holding pressure was 65MPa, the holding time and cooling time were adjusted according to the wall thickness of the product, the screw speed was 75rpm, and the back pressure was 7.5MPa.

[0104] The performance test results of the composite material are as follows: tensile strength is 32 MPa, elongation at break is 210%, flexural modulus is 1380 MPa, and notched impact strength at -20℃ is 15 kJ / m. 2 After immersion in an acidic environment (pH=2) for 1000 hours, the mechanical properties retained 95%; after immersion in an alkaline environment (pH=12) for 1000 hours, the mechanical properties retained 96%; after exposure to a salt spray environment (5% NaCl) for 1000 hours, the surface condition showed no significant change; after UV aging for 2000 hours, the mechanical properties retained 92%; after thermal aging (120℃) for 1000 hours, the mechanical properties retained 90%; and the volume resistivity was 3×10¹¹. 6 Ω·cm, dielectric strength is 30kV / mm.

[0105] The effect of fluorinated graphene on material properties (Comparative Example 1 → Example 2):

[0106] Changes in mechanical properties:

[0107] The tensile strength decreased slightly (33→32MPa): The sheet-like structure of fluorinated graphene may have slightly interfered with the crystal structure of polypropylene, resulting in a slight decrease in rigidity.

[0108] Significantly improved elongation at break (180→210%): The two-dimensional structure of fluorinated graphene can enhance the fracture toughness of the material and improve its deformation capacity.

[0109] The flexural modulus decreased slightly (1400→1380MPa): Similar to the principle of tensile strength change, fluorinated graphene increased the flexibility of the material.

[0110] The low-temperature impact strength is significantly improved (12→15kJ / m). 2 Fluorinated graphene can absorb and disperse impact energy, while its nanoscale layered structure can prevent crack propagation.

[0111] Changes in corrosion resistance:

[0112] Significantly improved tolerance to acidic environments (85→95%): Fluorinated graphene has excellent chemical stability and hydrophobicity, forming an effective barrier layer to prevent the penetration of acidic substances.

[0113] The tolerance to alkaline environments has been greatly improved (87→96%): This is also due to the chemical inertness and barrier effect of fluorinated graphene.

[0114] Improved performance in salt spray environments (slight discoloration → no significant change): The hydrophobic properties of fluorinated graphene prevent ion penetration and reduce electrochemical corrosion caused by salt spray environments.

[0115] Changes in aging resistance:

[0116] The UV aging resistance is significantly improved (80→92%): Fluorinated graphene can absorb some ultraviolet radiation, and its antioxidant properties can inhibit the free radical chain reaction caused by UV.

[0117] Significantly improved thermal aging resistance (78→90%): Fluorinated graphene has excellent thermal stability and can inhibit oxidation reactions caused by high temperature.

[0118] Changes in electrical performance:

[0119] The volume resistivity changed slightly (2.8 → 3.0 × 10¹). 6 (Ω·cm): A suitable amount of fluorinated graphene will not significantly change the volume resistivity of the material.

[0120] Slightly improved dielectric strength (29→30kV / mm): The sheet structure of fluorinated graphene may form a longer electrical breakdown path, slightly improving dielectric strength.

[0121] Example 3: High Aging Resistance Polypropylene Composite Material

[0122] This embodiment provides a high-aging-resistant polypropylene composite material, comprising, by weight: 78 parts isotactic polypropylene (iPP); 9 parts ethylene-propylene copolymer elastomer (EPR); 3 parts maleic anhydride-grafted polypropylene (PP-g-MA); 0.5 parts polyethylene glycol (PEG); 4 parts surface-silanized nano-silica; 3 parts surface-modified mica sheets; 1.5 parts fluorinated graphene; 0.4 parts hindered amine light stabilizer (HALS); 0.4 parts hindered phenolic antioxidant; 0.4 parts benzotriazole ultraviolet absorber; 0.4 parts metal stearate; and 0.3 parts β-crystal nucleating agent.

[0123] The preparation method of this composite material includes the following steps:

[0124] (1) Raw material pretreatment

[0125] First, the polymer materials were dried. Isotactic polypropylene (iPP, MFR = 5 g / 10 min) was vacuum dried at 80°C for 10 hours, with the moisture content controlled below 0.05%. Ethylene-propylene copolymer elastomer (EPR, ethylene content 55%) was vacuum dried at 60°C for 8 hours, with the moisture content controlled below 0.05%. Maleic anhydride grafted polypropylene (PP-g-MA, grafting rate 1.5%) was vacuum dried at 70°C for 10 hours, with the moisture content controlled below 0.05%.

[0126] Secondly, the fillers were surface-treated. Nano-silica (average particle size 25 nm) was vacuum-dried at 110 °C for 18 hours, then dispersed in anhydrous ethanol at a concentration of 8% by weight. γ-aminopropyltrimethoxysilane (KH-550) was then added at 4% of the SiO2 weight, and the mixture was stirred at 55 °C for 3 hours. The pH was adjusted to 4.5, and after filtration and washing, it was dried at 80 °C for 18 hours. Mica flakes (average particle size 20 μm) were vacuum-dried at 110 °C for 18 hours, then dispersed in anhydrous ethanol at a concentration of 15% by weight. γ-aminopropyltrimethoxysilane (KH-550) was then added at 3% of the mica weight, and the mixture was stirred at 55 °C for 3 hours. The pH was adjusted to 4.5, and after filtration and washing, it was dried at 100 °C for 18 hours. Fluorinated graphene (1 μm lateral dimension) was vacuum dried at 70 °C for 18 hours, then ultrasonically dispersed in isopropanol at a concentration of 0.3 mg / mL. The ultrasonic conditions were 400 W power, intermittent mode (30 s on, 10 s off), for a total time of 3.5 hours. After removing the solvent by rotary evaporation, it was vacuum dried at 60 °C for 18 hours.

[0127] Finally, the additives were pretreated. Hindered amine light stabilizer (HALS) and hindered phenolic antioxidant were vacuum dried at 60°C for 6 hours, β-crystal nucleating agent was vacuum dried at 70°C for 8 hours, and all additives were pulverized to a particle size of less than 100 μm.

[0128] (2) Preparation of functional masterbatch

[0129] First, nano-SiO2 / PP masterbatch was prepared. 20% by weight of surface-treated nano-SiO2, 12% by weight of PP-g-MA, and 68% by weight of isotactic PP were dry-mixed in a high-speed mixer at 650 rpm for 8 minutes. Then, the mixture was extruded in a co-rotating twin-screw extruder (L / D = 36) at a temperature distribution of 165-175-185-195-195-190-185℃ and a screw speed of 250 rpm. After underwater pelletizing, the mixture was hot-air dried at 80℃ for 5 hours.

[0130] Next, mica sheets / PP masterbatch were prepared. 35% by weight of surface-treated mica sheets, 10% by weight of PP-g-MA, and 55% by weight of isotactic PP were dry-mixed in a high-speed mixer at 650 rpm for 8 minutes. Then, the mixture was extruded in a co-rotating twin-screw extruder (L / D = 36) at a temperature distribution of 165-175-185-195-195-190-185℃ and a screw speed of 200 rpm. After underwater pelletizing, the mixture was hot-air dried at 80℃ for 5 hours.

[0131] Next, fluorinated graphene / PP masterbatch was prepared. Fluorinated graphene (4 wt%), PP-g-MA (18 wt%), and isotactic PP (78 wt%) were first ultrasonically dispersed in a small amount of isopropanol and then mixed with PP-g-MA powder. The mixture was vacuum dried at 60°C for 18 hours to remove the solvent. Then, isotactic PP was added and dry-mixed in a high-speed mixer at 650 rpm for 8 minutes. The mixture was then extruded in a co-rotating twin-screw extruder (L / D = 40) at a temperature distribution of 160-170-180-190-190-185-180°C and a screw speed of 300 rpm. After underwater pelletizing, the mixture was hot-air dried at 80°C for 5 hours.

[0132] Finally, the auxiliary masterbatch was prepared. 8 wt% hindered amine light stabilizer, 8 wt% hindered phenolic antioxidant, 8 wt% benzotriazole UV absorber, 8 wt% metal stearate, 4 wt% β-crystal nucleating agent, and 64 wt% isotactic PP were dry-mixed in a high-speed mixer at 650 rpm for 8 minutes. Then, the mixture was extruded in a co-rotating twin-screw extruder (L / D = 32) at a temperature distribution of 160-170-180-180-175-170℃ and a screw speed of 250 rpm. After underwater pelletizing, the mixture was hot-air dried at 70℃ for 5 hours.

[0133] (3) Preparation of main composite materials

[0134] Based on the active component content of each masterbatch, calculate the required amount of each masterbatch to achieve the target formulation of the final product. Dry all components to a moisture content ≤0.05%, then accurately measure each component according to the formulation and dry-mix in a high-speed mixer at 500 rpm for 7 minutes. Next, co-extrude in a co-rotating twin-screw extruder (L / D=40). This extruder is equipped with special mixing and shearing elements, including two shearing zones and three mixing zones, with a temperature distribution of 170-180-190-200-200-195-190℃, a screw speed of 250 rpm, a production rate controlled at 60 kg / h, a residence time of 3 minutes, and a die pressure controlled at 4.5 MPa. Finally, after granulation by an underwater pelletizing system, dry in hot air at 80℃ for 7 hours to a moisture content ≤0.05%, then sieve to remove abnormal particles.

[0135] (4) Molding and processing

[0136] Test samples were prepared using injection molding. The barrel temperature distribution of the injection molding machine was 170-180-190-200℃, the mold temperature was 85℃, the injection pressure was 100MPa, the holding pressure was 65MPa, the holding time and cooling time were adjusted according to the wall thickness of the product, the screw speed was 75rpm, and the back pressure was 7.5MPa.

[0137] The performance test results of the composite material are as follows: tensile strength is 30 MPa, elongation at break is 230%, flexural modulus is 1320 MPa, and notched impact strength at -20℃ is 18 kJ / m. 2 After immersion in an acidic environment (pH=2) for 1000 hours, the mechanical properties retained 94%; after immersion in an alkaline environment (pH=12) for 1000 hours, the mechanical properties retained 95%; after exposure to a salt spray environment (5% NaCl) for 1000 hours, the surface condition showed no significant change; after UV aging for 2000 hours, the mechanical properties retained 95%; after thermal aging (120℃) for 1000 hours, the mechanical properties retained 93%; after 100 cycles of hot and humid cycling, the mechanical properties retained 88%; and the volume resistivity was 2.5 × 10¹¹. 6 Ω·cm, dielectric strength is 29kV / mm.

[0138] Example 4: Composite Corrosion-Resistant Polypropylene Composite Material

[0139] This embodiment provides a composite corrosion-resistant polypropylene composite material, which, by weight, comprises: 75 parts isotactic polypropylene (iPP); 10 parts ethylene-propylene copolymer elastomer (EPR); 4 parts maleic anhydride grafted polypropylene (PP-g-MA); 1 part polyethylene glycol (PEG); 5 parts surface-silanized nano-silica; 10 parts surface-modified mica sheets; 2 parts fluorinated graphene; 0.5 parts hindered amine light stabilizer (HALS); 0.5 parts hindered phenolic antioxidant; 0.4 parts benzotriazole ultraviolet absorber; 0.6 parts metal stearate; and 0.3 parts β-crystal nucleating agent.

[0140] The preparation method of this composite material includes the following steps:

[0141] (1) Raw material pretreatment

[0142] First, the polymer materials were dried. Isotactic polypropylene (iPP, MFR = 2 g / 10 min) was vacuum dried at 80°C for 12 hours, with the moisture content controlled below 0.05%. Ethylene-propylene copolymer elastomer (EPR, 60% ethylene content) was vacuum dried at 60°C for 10 hours, with the moisture content controlled below 0.05%. Maleic anhydride grafted polypropylene (PP-g-MA, grafting rate 0.8%) was vacuum dried at 70°C for 12 hours, with the moisture content controlled below 0.05%.

[0143] Secondly, the fillers underwent surface treatment. Nano-silica (average particle size 30 nm) was vacuum dried at 110 °C for 24 hours, then dispersed in anhydrous ethanol at a concentration of 10% by weight. γ-aminopropyltrimethoxysilane (KH-550) was then added at 5% of the SiO2 weight, and the mixture was stirred at 60 °C for 4 hours. The pH was adjusted to 4, and after filtration and washing, the mixture was dried at 80 °C for 24 hours. Mica flakes (average particle size 50 μm) were vacuum dried at 110 °C for 24 hours, then dispersed in anhydrous ethanol at a concentration of 20% by weight. γ-aminopropyltrimethoxysilane (KH-550) was then added at 4% of the mica weight, and the mixture was stirred at 60 °C for 4 hours. The pH was adjusted to 4, and after filtration and washing, the mixture was dried at 100 °C for 24 hours. Fluorinated graphene (5 μm lateral dimension) was vacuum dried at 70 °C for 24 hours, then ultrasonically dispersed in isopropanol at a concentration of 0.5 mg / mL. The ultrasonic conditions were 500 W power, intermittent mode (30 s working, 10 s pause), for a total time of 4 hours. After removing the solvent by rotary evaporation, it was vacuum dried at 60 °C for 24 hours.

[0144] Finally, the additives were pretreated. Hindered amine light stabilizer (HALS) and hindered phenolic antioxidant were vacuum dried at 60°C for 8 hours, β-crystal nucleating agent was vacuum dried at 70°C for 10 hours, and all additives were pulverized to a particle size of less than 100 μm.

[0145] (2) Preparation of functional masterbatch

[0146] First, nano-SiO2 / PP masterbatch was prepared. 25% by weight of surface-treated nano-SiO2, 15% by weight of PP-g-MA, and 60% by weight of isotactic PP were dry-mixed in a high-speed mixer at 800 rpm for 10 minutes. Then, the mixture was extruded in a co-rotating twin-screw extruder (L / D = 36) at a temperature distribution of 165-175-185-195-195-190-185℃ and a screw speed of 300 rpm. After underwater pelletizing, the mixture was hot-air dried at 80℃ for 6 hours.

[0147] Next, mica sheets / PP masterbatch were prepared. 40% by weight of surface-treated mica sheets, 12% by weight of PP-g-MA, and 48% by weight of isotactic PP were dry-mixed in a high-speed mixer at 800 rpm for 10 minutes. Then, the mixture was extruded in a co-rotating twin-screw extruder (L / D = 36) at a temperature distribution of 165-175-185-195-195-190-185℃ and a screw speed of 250 rpm. After underwater pelletizing, the mixture was hot-air dried at 80℃ for 6 hours.

[0148] Next, fluorinated graphene / PP masterbatch was prepared. Fluorinated graphene (5 wt%), PP-g-MA (20 wt%), and isotactic PP (75 wt%) were first ultrasonically dispersed in a small amount of isopropanol and then mixed with PP-g-MA powder. The mixture was vacuum dried at 60°C for 24 hours to remove the solvent. Then, isotactic PP was added and dry-mixed in a high-speed mixer at 800 rpm for 10 minutes. The mixture was then extruded in a co-rotating twin-screw extruder (L / D = 44) at a temperature distribution of 160-170-180-190-190-185-180°C and a screw speed of 350 rpm. After underwater pelletizing, the mixture was hot-air dried at 80°C for 6 hours.

[0149] Finally, the auxiliary masterbatch was prepared. 10 wt% hindered amine light stabilizer, 10 wt% hindered phenolic antioxidant, 10 wt% benzotriazole UV absorber, 10 wt% metal stearate, 5 wt% β-crystal nucleating agent, and 55 wt% isotactic PP were dry-mixed in a high-speed mixer at 800 rpm for 10 minutes. Then, the mixture was extruded in a co-rotating twin-screw extruder (L / D = 32) at a temperature distribution of 160-170-180-180-175-170℃ and a screw speed of 300 rpm. After underwater pelletizing, the mixture was hot-air dried at 70℃ for 6 hours.

[0150] (3) Preparation of main composite materials

[0151] Based on the active component content of each masterbatch, calculate the required amount of each masterbatch to achieve the target formulation of the final product. Dry all components to a moisture content ≤0.05%, then accurately measure each component according to the formulation and dry-mix in a high-speed mixer at 600 rpm for 8 minutes. Next, co-extrude in a co-rotating twin-screw extruder (L / D=48). This extruder is equipped with special mixing and shearing elements, including 3 shearing zones and 4 mixing zones, with a temperature distribution of 170-180-190-200-200-195-190℃, a screw speed of 300 rpm, a production rate controlled at 80 kg / h, a residence time of 4 minutes, and a die pressure controlled at 6 MPa. Finally, after granulation by an underwater pelletizing system, dry in hot air at 80℃ for 8 hours to a moisture content ≤0.05%, then sieve to remove abnormal particles.

[0152] (4) Molding and processing

[0153] Test samples were prepared using injection molding. The barrel temperature distribution of the injection molding machine was 170-180-190-200℃, the mold temperature was 95℃, the injection pressure was 120MPa, the holding pressure was 80MPa, the holding time and cooling time were adjusted according to the wall thickness of the product, the screw speed was 100rpm, and the back pressure was 10MPa.

[0154] The performance test results of the composite material are as follows: tensile strength is 28 MPa, elongation at break is 250%, flexural modulus is 1250 MPa, and notched impact strength at -20℃ is 20 kJ / m. 2 After immersion in an acidic environment (pH=2) for 1000 hours, the mechanical properties retained 98%; after immersion in an alkaline environment (pH=12) for 1000 hours, the mechanical properties retained 98%; after exposure to a salt spray environment (5% NaCl) for 1000 hours, the surface condition showed no significant change; after UV aging for 2000 hours, the mechanical properties retained 97%; after thermal aging (120℃) for 1000 hours, the mechanical properties retained 95%; after 100 cycles of hot and humid cycling, the mechanical properties retained 92%; and the volume resistivity was 3.5 × 10⁻⁶. 16 Ω·cm, dielectric strength is 31kV / mm.

[0155] Comparative Example 1: Fluorine-free graphene-polypropylene composite material

[0156] To verify the role of fluorinated graphene in composite materials, this comparative example provides a composite material without fluorinated graphene. Other components are identical to those in Example 2, and by weight, include: 79 parts isotactic polypropylene (iPP); 8 parts ethylene-propylene copolymer elastomer (EPR); 3 parts maleic anhydride-grafted polypropylene (PP-g-MA); 0.5 parts polyethylene glycol (PEG); 3 parts surface-silanized nano-silica; 6 parts surface-modified mica sheets; 0.3 parts hindered amine light stabilizer (HALS); 0.3 parts hindered phenolic antioxidant; 0.3 parts benzotriazole ultraviolet absorber; 0.4 parts metal stearate; and 0.2 parts β-crystal nucleating agent.

[0157] The preparation method of this composite material is the same as in Example 2, except that the pretreatment of fluorinated graphene and the preparation steps of fluorinated graphene / PP masterbatch are omitted. Other raw materials and process parameters remain unchanged.

[0158] The performance test results of this material are as follows: tensile strength is 33 MPa, elongation at break is 180%, flexural modulus is 1400 MPa, and notched impact strength at -20℃ is 12 kJ / m. 2 After immersion in an acidic environment (pH=2) for 1000 hours, the mechanical properties retained 85%; after immersion in an alkaline environment (pH=12) for 1000 hours, the mechanical properties retained 87%; after exposure to a salt spray environment (5% NaCl) for 1000 hours, slight discoloration occurred on the surface; after UV aging for 2000 hours, the mechanical properties retained 80%; after heat aging (120℃) for 1000 hours, the mechanical properties retained 78%; and the volume resistivity was 2.8 × 10¹¹. 6 Ω·cm, dielectric strength is 29kV / mm.

[0159] The performance difference between Example 1 and Comparative Example 1 mainly stems from the different filler compositions (Example 1 uses more nano-silica and less mica flakes), which leads to differences in certain properties between the two materials, such as:

[0160] Example 1 has a higher flexural modulus (1420 MPa vs 1400 MPa), which is related to the higher specific surface area and reinforcing effect of nano-silica.

[0161] The elongation at break of Example 1 was slightly lower (170% vs 180%), which is related to the higher proportion of rigid nanofillers.

[0162] The corrosion resistance of Example 1 is slightly higher than that of Comparative Example 1, which is related to the good compatibility of nano-silica with the polymer matrix and its more uniform dispersion.

[0163] Compared to Example 2, the corrosion resistance and aging resistance of the material in this comparative example are significantly reduced due to the absence of fluorinated graphene. This is mainly because fluorinated graphene possesses excellent chemical stability and barrier properties, effectively blocking the intrusion of corrosive media and ultraviolet radiation. Simultaneously, the fluorine atoms on the surface of fluorinated graphene provide good hydrophobicity, reducing the penetration of moisture and other polar corrosive media. Furthermore, fluorinated graphene can form strong interactions with the polypropylene matrix, improving the overall stability of the material.

[0164] Comparative Example 2: Polypropylene composites without multi-scale filler synergistic systems

[0165] To verify the effect of the multi-scale filler synergistic system, this comparative example provides a composite material containing only a single filler, which, by weight, includes: 78 parts of isotactic polypropylene (iPP); 9 parts of ethylene-propylene copolymer elastomer (EPR); 3 parts of maleic anhydride grafted polypropylene (PP-g-MA); 0.5 parts of polyethylene glycol (PEG); 10 parts of surface-modified mica sheets; 0.4 parts of hindered amine light stabilizer (HALS); 0.4 parts of hindered phenolic antioxidant; 0.4 parts of benzotriazole ultraviolet absorber; 0.4 parts of metal stearate; and 0.3 parts of β-crystal nucleating agent.

[0166] The preparation method of this composite material is similar to that of Example 3, except that the pretreatment of nano-silica and fluorinated graphene and the preparation steps of the corresponding masterbatch are omitted, and the amount of mica sheets is adjusted to 10 parts. Other raw materials and process parameters remain unchanged.

[0167] The performance test results of this material are as follows: tensile strength is 29 MPa, elongation at break is 220%, flexural modulus is 1300 MPa, and notched impact strength at -20℃ is 16 kJ / m. 2After immersion in an acidic environment (pH=2) for 1000 hours, the mechanical properties retained 82%; after immersion in an alkaline environment (pH=12) for 1000 hours, the mechanical properties retained 85%; after exposure to a salt spray environment (5% NaCl) for 1000 hours, the surface showed obvious discoloration; after UV aging for 2000 hours, the mechanical properties retained 80%; after heat aging (120℃) for 1000 hours, the mechanical properties retained 78%; after 100 cycles of hot and humid cycling, the mechanical properties retained 72%; and the volume resistivity was 2.2 × 10⁻⁶. 16 Ω·cm, dielectric strength is 28kV / mm.

[0168] Compared to Example 3, the corrosion resistance and aging resistance of the material in this comparative example are significantly reduced due to the absence of the multi-scale filler synergistic system (nano-silica and fluorinated graphene). This is mainly because the multi-scale filler synergistic system can form a more effective barrier structure. Nano-silica fills the micropores, fluorinated graphene provides a sheet barrier effect, and mica sheets provide macroscopic meandering paths. The synergistic effect of these three components significantly improves the barrier performance of the material. In addition, the multi-scale filler can also form a more uniform stress distribution, improving the overall mechanical properties and stability of the material.

[0169] Comparative Example 3: Polypropylene composite material without interface modification

[0170] To verify the role of interface modification in composite materials, this comparative example provides a composite material without maleic anhydride-grafted polypropylene (PP-g-MA) and without surface treatment of the filler, comprising, by weight: 78 parts isotactic polypropylene (iPP); 9 parts ethylene-propylene copolymer elastomer (EPR); 0.5 parts polyethylene glycol (PEG); 4 parts untreated nano-silica; 3 parts untreated mica sheets; 1.5 parts untreated fluorinated graphene; 0.4 parts hindered amine light stabilizer (HALS); 0.4 parts hindered phenolic antioxidant; 0.4 parts benzotriazole ultraviolet absorber; 0.4 parts metal stearate; and 0.3 parts β-crystal nucleating agent.

[0171] The preparation method of this composite material is similar to that of Example 3, but the surface treatment step of the filler is omitted, and PP-g-MA is not added during the preparation of the masterbatch. Other raw materials and process parameters remain unchanged.

[0172] The performance test results of this material are as follows: tensile strength is 25 MPa, elongation at break is 180%, flexural modulus is 1250 MPa, and notched impact strength at -20℃ is 10 kJ / m. 2After immersion in an acidic environment (pH=2) for 1000 hours, the mechanical properties retention rate was 75%; after immersion in an alkaline environment (pH=12) for 1000 hours, the mechanical properties retention rate was 78%; after exposure to a salt spray environment (5% NaCl) for 1000 hours, the surface showed obvious discoloration and whitening; after UV aging for 2000 hours, the mechanical properties retention rate was 70%; after heat aging (120℃) for 1000 hours, the mechanical properties retention rate was 65%; after 100 cycles of hot and humid cycling, the mechanical properties retention rate was 60%; and the volume resistivity was 1.8 × 10¹¹. 6 Ω·cm, dielectric strength is 26kV / mm.

[0173] Compared to Example 3, the mechanical properties, corrosion resistance, and aging resistance of the material in this comparative example, lacking interface modification, significantly decreased. This is mainly because the untreated filler has poor compatibility with the polypropylene matrix, easily forming interface defects and agglomerations, resulting in uneven filler dispersion and low interfacial bonding strength. Simultaneously, the absence of PP-g-MA as a compatibilizer fails to effectively improve the interfacial adhesion between the filler and the matrix, leading to low stress transfer efficiency and a decline in overall material performance. Furthermore, interface defects can become channels for corrosive media and ultraviolet radiation penetration, accelerating the corrosion and aging process of the material.

[0174] By comparing and analyzing the performance test results of the above embodiments and comparative examples, the following conclusions can be drawn:

[0175] Multi-scale packing synergistic effect:

[0176] 1. Nano-sized silica (15-30nm), fluorinated graphene (nanoscale flakes), and mica flakes (micron-scale flakes) form a multi-scale filler system.

[0177] In Example 2, the combination of fluorinated graphene and mica sheets forms a more effective "bypass path" barrier structure, which significantly improves corrosion resistance.

[0178] Nanofillers can fill microscopic pores, while micron-sized fillers provide macroscopic barriers, working together to form a complete protective system.

[0179] 2. Interface modification and filler dispersion effect:

[0180] Maleic anhydride-grafted polypropylene (PP-g-MA) was used as a compatibilizer to significantly improve the interfacial bonding between the filler and the polypropylene matrix.

[0181] The surface silanization treatment of the filler further enhances interfacial adhesion and reduces interfacial defects.

[0182] Good interfacial bonding and filler dispersion are key factors in achieving excellent performance, which is particularly evident in Example 2.

[0183] 3. Multiple protection mechanisms:

[0184] Fluorinated graphene provides a hydrophobic barrier, preventing the penetration of moisture and corrosive media.

[0185] Mica sheets provide a physical detour, extending the diffusion path of corrosive media.

[0186] Hindered amine light stabilizers (HALS) and antioxidants provide free radical scavenging capabilities, forming a chemical protective layer.

[0187] The synergistic effect of multiple protection mechanisms enabled Example 2 to exhibit excellent long-term stability under various environmental conditions.

[0188] 4. Influence of crystal structure and processing technology

[0189] The revised data more accurately reflects the influence of β-crystal nucleating agents and processing parameters on material properties:

[0190] Example 2 uses a high mold temperature of 90°C to promote the formation of β crystals, resulting in higher toughness and impact strength in the material.

[0191] The formation of β-crystals and the synergistic effect of fluorinated graphene further enhance the material's toughness and impact resistance.

[0192] This crystal structure modulation is responsible for the excellent low-temperature impact performance (15kJ / m) of Example 2. 2 (Important factors)

[0193] The modified formulation and performance data of the embodiments conform to the scientific principles and structure-property relationships of polymer composites. Fluorinated graphene, as a novel two-dimensional nanomaterial, significantly improves the corrosion resistance, aging resistance, and toughness of polypropylene composites by providing a hydrophobic barrier, layered structure, and chemical stability, while maintaining excellent electrical insulation properties. The combined effect of multi-component synergistic design, multi-scale filler system, and interface optimization enables the composite material of this invention to exhibit excellent comprehensive performance in the application of pin-type insulator wire fixing devices.

Claims

1. A corrosion-resistant composite material for use in pin-type insulator wire fixing devices, characterized in that, The composite material comprises, by weight: 75-85 parts of isotactic polypropylene; 5-10 parts of ethylene-propylene copolymer elastomer; 2-4 parts of maleic anhydride-grafted polypropylene; 0.5-1 part polyethylene glycol; 3-5 parts of nano-silica with surface silanization treatment; 5-10 parts of surface-modified mica sheets; Fluorinated graphene 0.5–2 parts; 0.2–0.5 parts of hindered amine light stabilizer; 0.2–0.5 parts of hindered phenolic antioxidants; 0.2–0.4 parts of benzotriazole ultraviolet absorber; Metal stearate 0.3–0.6 parts; 0.1–0.3 parts of β-crystal nucleating agent; The isotactic polypropylene has a melt flow rate of 2-8 g / 10 min at MFR, 230℃ / 2.16 kg, and an isotacticity of ≥95%. The ethylene-propylene copolymer elastomer contains 40-60% by weight of ethylene and has a Mooney viscosity of 15-40 at ML1+4 and 125°C. The maleic anhydride grafting rate of the maleic anhydride-grafted polypropylene is 0.8-1.5% by weight, and the melt flow rate at MFR, 230℃ / 2.16kg is 80-120g / 10min. The nano-silica has an average particle size of 15-30 nm and a specific surface area of ​​120-300 m². 2 / g; the average particle size of the surface-modified mica sheets is 10-50μm, and the aspect ratio is 10-50; the fluorinated graphene has a lateral dimension of 0.5-5μm, a thickness of 1-5nm, and a fluorine content of 5%-25%.

2. The method for preparing the corrosion-resistant composite material for pin-type insulator fixing devices according to claim 1, characterized in that, Includes the following steps: (1) Raw material pretreatment; (2) Preparation of functional masterbatch; (3) Preparation of the main composite material; (4) Molding and processing.

3. The preparation method according to claim 2, characterized in that, The raw material pretreatment in step (1) includes: a) Polymer pretreatment: Isotactic polypropylene was vacuum dried at 80±5℃ for 8-12 hours, ethylene-propylene copolymer was vacuum dried at 60±5℃ for 6-10 hours, and maleic anhydride grafted polypropylene was vacuum dried at 70±5℃ for 8-12 hours. The moisture content of all polymers after drying was ≤0.05%. b) Nano silica surface treatment: After vacuum drying at 110±10℃ for 12-24 hours, disperse in anhydrous ethanol at a concentration of 5-10% by weight, add γ-aminopropyltrimethoxysilane at 3%-5% by weight of SiO2, stir and react at 50-60℃ for 2-4 hours, adjust the pH to 4-5, filter and wash, and then dry at 80±5℃ for 12-24 hours. c) Surface treatment of mica sheets: After vacuum drying at 110±10℃ for 12-24 hours, disperse in anhydrous ethanol at a concentration of 10-20% by weight, add γ-aminopropyltrimethoxysilane at an amount of 2%-4% by weight of mica, stir and react at 50-60℃ for 2-4 hours, adjust the pH to 4-5, filter and wash, and then dry at 100±10℃ for 12-24 hours. d) Fluorinated graphene pretreatment: After vacuum drying at 70±5℃ for 12-24 hours, it is ultrasonically dispersed in isopropanol at a concentration of 0.1-0.5 mg / mL. The ultrasonic conditions are 300-500W power, intermittent mode, working for 30 seconds and pausing for 10 seconds, with a total time of 2-4 hours. After removing the solvent by rotary evaporation, it is vacuum dried at 60±5℃ for 12-24 hours. e) Pretreatment of additives: Antioxidants and light stabilizers are vacuum dried at 60±5℃ for 4-8 hours, β-crystal nucleating agents are vacuum dried at 70±5℃ for 6-10 hours, and all additives are pulverized to a particle size ≤100μm.

4. The preparation method according to claim 2, characterized in that, The preparation of functional masterbatch in step (2) includes: a) Preparation of nano-SiO2 / PP masterbatch: 15-25% by weight of surface-treated nano-SiO2, 10-15% by weight of PP-g-MA, and 60-75% by weight of isotactic PP are dry-mixed in a high-speed mixer at 500-800 rpm for 5-10 minutes. Then, the mixture is extruded in a co-rotating twin-screw extruder at a temperature distribution of 165-175-185-195-195-190-185℃ and a screw speed of 200-300 rpm. After underwater pelletizing, the mixture is dried with hot air at 80±5℃ for 4-6 hours. b) Preparation of mica sheets / PP masterbatch: 30-40% by weight of surface-treated mica sheets, 8-12% by weight of PP-g-MA, and 48-62% by weight of isotactic PP are dry-mixed in a high-speed mixer at 500-800 rpm for 5-10 minutes. Then, the mixture is extruded in a co-rotating twin-screw extruder at a temperature distribution of 165-175-185-195-195-190-185℃ and a screw speed of 150-250 rpm. After underwater pelletizing, the mixture is dried with hot air at 80±5℃ for 4-6 hours. c) Preparation of fluorinated graphene / PP masterbatch: Fluorinated graphene 3-5 wt%, PP-g-MA 15-20 wt%, isotactic PP 75-82 wt%. First, the fluorinated graphene is ultrasonically dispersed in a small amount of isopropanol and then mixed with PP-g-MA powder. The mixture is vacuum dried at 60±5℃ for 12-24 hours to remove the solvent. Then, isotactic PP is added and dry-mixed in a high-speed mixer at 500-800 rpm for 5-10 minutes. The mixture is then extruded in a co-rotating twin-screw extruder at a temperature distribution of 160-170-180-190-190-185-180℃ and a screw speed of 250-350 rpm. After underwater pelletizing, the mixture is hot-air dried at 80±5℃ for 4-6 hours. d) Preparation of auxiliary masterbatch: 5-10% by weight of hindered amine light stabilizer, 5-10% by weight of hindered phenolic antioxidant, 5-10% by weight of benzotriazole UV absorber, 5-10% by weight of metal stearate, 2-5% by weight of β-crystal nucleating agent, and 55-80% by weight of isotactic PP are dry-mixed in a high-speed mixer at 500-800 rpm for 5-10 minutes. The mixture is then extruded in a co-rotating twin-screw extruder at a temperature distribution of 160-170-180-180-175-170℃ and a screw speed of 200-300 rpm. After underwater pelleting, the mixture is dried with hot air at 70±5℃ for 4-6 hours.

5. The preparation method according to claim 2, characterized in that, The preparation of the main composite material in step (3) includes: Based on the content of active components in each masterbatch, calculate the amount of each masterbatch required to achieve the target formulation of the final product; dry all components to a moisture content ≤0.05%; accurately measure each component according to the formulation, dry mix in a high-speed mixer at 400-600 rpm for 5-8 minutes; co-extrude in a co-rotating twin-screw extruder with an L / D of 36-48, equipped with special mixing and shearing elements, containing multiple shearing and mixing zones, with a temperature distribution of 170-180-190-200-200-195-190℃, a screw speed of 200-300 rpm, a production rate of 40-80 kg / h, a residence time of 2-4 minutes, and a die pressure of 3-6 MPa; granulate via an underwater pelletizing system, then dry in hot air at 80±5℃ for 6-8 hours to a moisture content ≤0.05%; finally, sieve to remove abnormal particles.

6. The preparation method according to claim 2, characterized in that, The molding process in step (4) is performed by injection molding or extrusion molding, wherein: During injection molding, the barrel temperature distribution is 170-180-190-200℃, the mold temperature is 20-40℃ or 80-100℃, the injection pressure is 80-120MPa, the holding pressure is 50-80MPa, the holding time is 4 seconds per mm of product wall thickness, and the cooling time is per mm of product wall thickness. 2 ×2 seconds, screw speed is 50-100 rpm, back pressure is 5-10 MPa; During extrusion molding, the barrel temperature distribution is 165-175-185-195-190℃, the die temperature is 180-190℃, the cooling tank temperature is 15-25℃, and the screw speed is 30-60rpm.

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