High-temperature-resistant insulating flame-retardant multifunctional master batch, preparation method and application thereof

Abstract

This invention discloses a high-temperature resistant, insulating, and flame-retardant multifunctional masterbatch, its preparation method, and its applications, belonging to the field of polymer material modification technology. The masterbatch comprises, by weight, 15-25 parts of carrier resin, 40-55 parts of core-shell microcapsule flame-retardant powder, 12-22 parts of composite nano-insulating modifier, 6-10 parts of dispersant, 3-5 parts of antioxidant, and 8-12 parts of compatibilizer. The core-shell microcapsule flame-retardant powder uses melamine-formaldehyde resin as the shell layer, and the core material is composed of ammonium polyphosphate, melamine cyanurate, nano-silica, and nano-titanium dioxide; the composite nano-insulating modifier is a compound of nano-boron nitride and nano-alumina. This invention utilizes the synergistic design of a microencapsulated phosphorus-nitrogen-silicon-titanium quaternary synergistic flame-retardant system and a composite nano-insulating system to create a material that possesses excellent insulation properties (volume resistivity ≥ 5 × 10¹⁵ Ω·cm), flame-retardant properties (UL94 V-0 rating), and high temperature resistance (long-term operating temperature ≥ 160℃). By blending this masterbatch with a base resin and glass fiber and then melt-injecting, high-voltage connector insulators can be produced, which are widely used in new energy vehicles, rail transportation, and other fields.

Description

Technical Field

[0001] This invention relates to the field of polymer material modification and supporting materials for high-voltage electrical components, specifically to a high-temperature resistant, insulating, and flame-retardant multifunctional masterbatch, along with its preparation method and application in high-voltage connector insulation materials. This invention is applicable to the manufacture of connector insulation components in high-voltage, high-temperature, and harsh environments such as new energy vehicles, rail transit, and power transmission. Background Technology

[0002] As the core connection hub of high-voltage electrical systems, the performance of the insulator (inner plastic shell) of a high-voltage connector directly determines its insulation reliability, safety, and service life. With the development of new energy vehicles, rail transportation, and other fields towards higher voltage and higher power density, more stringent requirements are being placed on the comprehensive performance of the insulator: it must simultaneously possess excellent electrical insulation performance (high insulation resistance and breakdown strength), good flame retardant performance (UL94 V-0 rating, no dripping, low smoke toxicity), and stable temperature resistance (suitable for a wide operating temperature range of -40℃ to 180℃).

[0003] Currently, the commonly used base materials for high-voltage connector insulators, such as polyamide 66 (PA66) and polybutylene terephthalate (PBT), are engineering plastics with insufficient flame retardancy, and their temperature resistance and long-term insulation stability are difficult to meet stringent requirements. Therefore, they usually need to be modified by adding glass fiber, flame retardants, insulation modifiers, etc.

[0004] Existing modification technologies mostly employ a direct blending method of "base resin + functional additives," which suffers from drawbacks such as uneven additive dispersion, poor compatibility, easy migration and precipitation, and decreased processing performance. In particular, traditional flame retardants (such as ordinary ammonium polyphosphate) have poor compatibility with the resin matrix and are prone to hydrolysis and migration under high temperature and humidity environments, leading to a significant decrease in the material's insulation and flame retardant properties. Furthermore, the lack of synergistic design between flame retardants and insulating fillers often results in the contradiction of "better flame retardancy, worse insulation."

[0005] Therefore, developing a multifunctional masterbatch with excellent insulation properties, stable flame retardant effect, good temperature resistance, good compatibility with high voltage connector substrate resin, and convenient processing has significant technical value and market prospects. Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] This invention aims to overcome the shortcomings of existing technologies, such as the difficulty in simultaneously achieving insulation, flame retardancy, and temperature resistance, as well as the poor long-term stability caused by the easy hydrolysis and migration of flame retardants. It provides a high-temperature-resistant, insulating, and flame-retardant multifunctional masterbatch, its preparation method, and its applications. Through the synergistic design of a core-shell microcapsule-encapsulated phosphorus-nitrogen-silicon-titanium quaternary synergistic flame-retardant system and a composite nano-insulation modification system, the material simultaneously achieves high insulation resistance (volume resistivity ≥ 5 × 10¹). 5 It boasts comprehensive performance including Ω·cm, high flame retardancy rating (UL94V-0), and long-term operating temperature ≥160℃.

[0008] (II) Technical Solution A high-temperature resistant, insulating, flame-retardant, multifunctional masterbatch, by weight, comprises the following components: Carrier resin: 15 to 25 parts; Core-shell microcapsule flame retardant powder: 40 to 55 parts; Composite nano-insulating modifier: 12 to 22 parts; Dispersant: 6 to 10 parts; Antioxidant: 3 to 5 parts; Compatibilizer: 8 to 12 parts.

[0009] The core-shell microcapsule flame-retardant powder uses melamine-formaldehyde resin as the shell layer, and the core material is composed of ammonium polyphosphate, melamine cyanurate, nano-silica, and nano-titanium dioxide. Under combustion conditions, the nano-silica and nano-titanium dioxide, together with nano-boron nitride and nano-alumina in the composite nano-insulating modifier, construct an inorganic nano-network structure and participate in the formation of the expanded char layer.

[0010] The composite nano-insulating modifier is prepared by compounding nano-boron nitride, nano-alumina, and a silane coupling agent in a high-speed mixer; the nano-boron nitride and nano-alumina have a particle size of 50nm to 180nm; the weight ratio of nano-boron nitride, nano-alumina, and the silane coupling agent is 1:(1.2 to 2.0):(0.01 to 0.05); the silane coupling agent is KH-550 or KH-560.

[0011] Furthermore, the preparation method of the core-shell microcapsule flame retardant powder includes the following steps: S1. Core material pretreatment: Ammonium polyphosphate, melamine cyanurate, nano-silica, and nano-titanium dioxide are added to a high-speed mixer in a weight ratio of 1:(0.25 to 0.38):(0.2 to 0.3):(0.075 to 0.15). Water is added at 50 to 200 times the total weight of the powder. The mixture is stirred at high speed (600 to 1000 rpm) for 10 to 30 minutes. Then, a dilute ethanol solution of KH-550 is added, and the mixture is stirred at high speed for another 3 to 10 minutes. The molecular weight of the ammonium polyphosphate is ≥1000. The amount of KH-550 is 0.5% to 2% of the weight of the ammonium polyphosphate.

[0012] S2. Melamine dispersion: Heat to 90-100℃, add melamine powder, and stir at high speed (600-1000 rpm) for 30-60 min; the melamine powder accounts for 5% to 10% of the weight of ammonium polyphosphate.

[0013] S3. Add formaldehyde: Cool to 60-85℃, stir (400-800 rpm), adjust the pH of the system to 8-9 with hexamethylenetetramine or triethanolamine, and then slowly add formaldehyde solution (37% aqueous solution), react for 30-60 min; the amount of formaldehyde solution added should make the molar ratio of formaldehyde to melamine (2-12):1.

[0014] S4. Polycondensation and coating: Cool to below 60℃, stir (400-800 rpm) and slowly adjust the pH of the system to 4.5-6.5 with hydrochloric acid, and react for 30-60 minutes.

[0015] S5. Curing and crosslinking: Cool to room temperature, filter, wash the filter cake with distilled water until neutral, heat to 90-100℃ and keep warm for 4 hours; heat to 115-125℃ and vacuum dry for 4 hours.

[0016] S6. Crushing and sieving: Crush and sieve through a 200-325 mesh sieve to obtain a white powdery core-shell microcapsule flame retardant powder.

[0017] Furthermore, the carrier resin is selected from polyamide 6 (PA6) and polybutylene terephthalate (PBT).

[0018] Furthermore, the dispersant is one or more of polyethylene wax, polypropylene wax, fatty acids and their metal soaps, fatty acid esters, and silicone dispersants.

[0019] Furthermore, the antioxidant is a binary compound of hindered phenolic antioxidant and phosphite antioxidant, with a compound weight ratio of 1:(1-1.5).

[0020] Furthermore, the compatibilizer is one or more of maleic anhydride grafted compatibilizers and glycidyl methacrylate grafted compatibilizers.

[0021] This invention also provides a method for preparing the above-mentioned high-temperature resistant, insulating, flame-retardant, multifunctional masterbatch, comprising the following steps: (1) Premixing treatment: Weigh all components according to the weight parts. First, put the carrier resin into a high-speed mixer and preheat it for 6 to 9 minutes at a speed of 700 to 900 r / min and a temperature of 75°C to 85°C. Then, add the composite nano insulating modifier, dispersant and compatibilizer in sequence and mix at a speed of 550 to 750 r / min for 6 to 9 minutes. Finally, add the core-shell microcapsule flame retardant powder and antioxidant, adjust the speed to 1200 to 1500 r / min and the temperature to 90°C to 110°C, and mix for 20 to 35 minutes to obtain the premix.

[0022] (2) Melt blending and extrusion: The premixed material is fed into a twin-screw extruder with a length-to-diameter ratio of 40:1 to 45:1, a screw speed of 250 to 500 r / min, an extrusion pressure of 20 MPa to 30 MPa, and the temperature of each section is set as follows: feeding section 170℃ to 190℃, melting section 210℃ to 250℃, homogenization section 230℃ to 250℃, and die head temperature 220℃ to 240℃ for melt blending and extrusion; the twin-screw extruder adopts a combined screw and is equipped with 5 to 6 dispersing sections and 2 to 3 melting sections.

[0023] (3) Post-processing: The strands extruded by the twin-screw extruder are water-cooled at 25℃ to 40℃ and air-dried at a wind speed of 3m / s to 5m / s. After being granulated, they are sieved through a 4-mesh to 8-mesh sieve and dried with hot air circulation at 90℃ to 110℃ for 4h to 6h. After drying, the moisture content of the masterbatch is ≤0.08%. After cooling to room temperature, the high temperature resistant, insulating, flame retardant, and multifunctional masterbatch is obtained.

[0024] The present invention also provides the application of the above-mentioned high temperature resistant, insulating, flame retardant, multifunctional masterbatch in high voltage connector insulators. The application method is as follows: the high temperature resistant, insulating, flame retardant, multifunctional masterbatch is mixed with the substrate resin for high voltage connector insulators at a weight ratio of (20 to 35): (65 to 80), and the resulting mixture is then extruded and granulated with glass fiber at a weight ratio of 70:30 using a twin-screw extruder. After melt injection molding, a high voltage connector insulator is prepared.

[0025] (III) Beneficial Effects

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. A core-shell microcapsule-encapsulated phosphorus-nitrogen-silicon-titanium quaternary synergistic flame retardant system was constructed: melamine-formaldehyde resin was used as the shell layer, completely encapsulating ammonium polyphosphate, MCA, nano-SiO2, and nano-TiO2 as the quaternary synergistic core material. This microcapsule structure has multiple advantages: the shell layer blocks moisture, inhibiting the hydrolytic migration of ammonium polyphosphate and solving the problem of easy precipitation in traditional flame retardants; at high temperatures, the shell layer and core material synergistically form carbon, creating a P-Ti-O-Si inorganic hybrid network structure, catalyzing the formation of a dense and robust expanded carbon layer; nano-SiO2 and TiO2 act as physical crosslinking points, restricting polymer molecular chain movement and increasing the material's heat distortion temperature. The obtained masterbatch and its modified materials achieve a flame retardant rating of UL94 V-0 (no dripping) and a limiting oxygen index ≥32%. After hot air aging at 180℃ for 1000h, the tensile strength retention rate is ≥85%, and the volume resistivity retention rate is ≥85%.

[0028] 2. Synergistic improvement in insulation and flame retardant properties: A composite nano-insulation modifier, made of nano-boron nitride and nano-alumina and surface-activated, forms a synergistic effect with the silicon and titanium components in the microcapsule flame retardant powder. Nano-boron nitride constructs microscopic thermally conductive pathways, avoiding localized heat accumulation and inhibiting thermal degradation; surface-activated nano-alumina enhances the inorganic-organic interface bonding, resisting microcracks caused by high-temperature thermal expansion. This results in a volume resistivity of the modified material ≥5×10¹. 5 It has a strength of Ω·cm and a breakdown strength of ≥31 kV / mm, while also exhibiting good thermal conductivity and mechanical reinforcement.

[0029] 3. Overcoming the technical prejudice that "flame retardancy and insulation are mutually exclusive": Through cross-component synergistic design of flame-retardant microcapsules and insulating modifiers, under combustion conditions, the nano-SiO2 / TiO2 released by the microcapsules and the nano-BN / Al2O3 in the insulating modifier jointly participate in the construction of an inorganic-organic hybrid carbon layer, which not only improves the flame retardant efficiency but also protects the insulating structure of the polymer matrix. Experiments have shown that the material of this invention can still maintain ≥5×10¹ flame retardancy at the UL94 V-0 flame retardancy rating. 5 The volume resistivity of Ω·cm has broken the industry's understanding.

[0030] 4. A synergistic chemical and physical mechanism for resisting thermal aging was established: the hindered phenol / phosphite binary antioxidant system chemically inhibits the thermal oxidative degradation of the material; the inorganic hybrid network formed by the composite nano-insulating modifier and the decomposition products of the microcapsule flame retardant powder constructs a thermal-oxidative barrier at the physical level. The synergistic effect of the chemical and physical mechanisms ensures that the material retains ≥85% of its performance after aging in hot air at 180℃ for 1000h.

[0031] 5. The formulation and process have been optimized to ensure good compatibility and processability: By selecting carrier resins, compatibilizers and binary antioxidant systems that match the substrate, and optimizing the premixing and melt blending processes, the uniform dispersion of each functional component in the masterbatch and the final product has been ensured, solving the problems of additive precipitation and material stratification. The masterbatch has good processing fluidity and is compatible with existing molding processes. Detailed Implementation

[0032] The present invention will be described in more detail below with reference to embodiments, but the scope of protection of the present invention is not limited to these embodiments. Unless otherwise stated, the raw materials used in the embodiments are commercially available and conventional equipment is known in the art.

[0033] In this invention, the molecular weight of ammonium polyphosphate is ≥1000 and the degree of polymerization n is ≥20; the particle size range of nano boron nitride and nano alumina is 50nm~180nm.

[0034] The performance testing method is as follows: - Volume resistivity (R v Tested according to GB / T 1410-2006 standard; - Breakdown strength (V) s Tested according to GB / T 1408.1-2016 standard; - Flame retardant performance: Tested according to UL 94 standard, sample thickness 1.6mm; - Limiting Oxygen Index (LOI): Tested according to GB / T 2406.2-2009 standard; - Long-term operating temperature: Based on the retention rate of tensile strength (≥70%) and volume resistivity (≥10¹) after aging in hot air at 180℃ for 1000h. 5 (Ω·cm) comprehensive evaluation; - High temperature and high humidity aging: carried out under conditions of 85℃ / 85% RH×1000h, and the volume resistivity retention rate after aging was tested.

[0035] I. Preparation of Core-Shell Microcapsule Flame Retardant Powder

[0036] Preparation Example 1

[0037] This preparation example provides a method for preparing core-shell microcapsule flame retardant powder (denoted as M-1), including the following steps: S1. Core material pretreatment: Ammonium polyphosphate (molecular weight 1500), melamine cyanurate, nano silica (average particle size 60nm), and nano titanium dioxide (average particle size 50nm) are added to a high-speed mixer in a weight ratio of 1:0.30:0.25:0.10. Deionized water with a total weight of 100 times the powder is added. After stirring at 800 rpm for 20 min, a dilute ethanol solution of KH-550 (KH-550 to anhydrous ethanol volume ratio 1:5) accounting for 1% of the weight of ammonium polyphosphate is added, and stirring at high speed is continued for 5 min.

[0038] S2. Melamine dispersion: Heat the system to 95°C, add melamine powder accounting for 8% of the weight of ammonium polyphosphate, and stir at high speed at 800 rpm for 45 min.

[0039] S3. Add formaldehyde: Cool to 75℃, adjust the stirring speed to 600 rpm, adjust the pH of the system to 8.5 with triethanolamine, and then slowly add 37% formaldehyde solution. The molar ratio of formaldehyde to melamine is 6:1. React for 45 minutes.

[0040] S4. Polycondensation and coating: Cool to 55℃, adjust the pH of the system to 5.5 with 10% hydrochloric acid, and continue the reaction for 45 minutes.

[0041] S5. Curing and crosslinking: After the reaction is complete, cool to room temperature, filter, wash the filter cake with distilled water until neutral, then heat to 95°C and keep warm for 4 hours; then heat to 120°C and vacuum dry for 4 hours.

[0042] S6. Crushing and sieving: Crush the dried product and pass it through a 250-mesh sieve to obtain white powdery core-shell microcapsule flame retardant powder M-1.

[0043] Preparation Example 2 This preparation example is basically the same as Preparation Example 1, except for the adjustment of the core material ratio and process parameters: the weight ratio of ammonium polyphosphate, melamine cyanurate, nano-silica, and nano-titanium dioxide is 1:0.25:0.20:0.075; the molar ratio of formaldehyde to melamine is 4:1. The core-shell microcapsule flame retardant powder M-2 was finally obtained.

[0044] Preparation Example 3 This preparation example is basically the same as Preparation Example 1, except for the adjustment of the core material ratio and process parameters: the weight ratio of ammonium polyphosphate, melamine cyanurate, nano-silica, and nano-titanium dioxide is 1:0.38:0.30:0.15; the molar ratio of formaldehyde to melamine is 10:1. The core-shell microcapsule flame retardant powder M-3 was finally obtained.

[0045] II. Preparation of Composite Nano-Insulation Modifiers Preparation Example 4 This preparation example provides a method for preparing a composite nano-insulating modifier (denoted as N-1): nano boron nitride (average particle size 80 nm), nano alumina (average particle size 100 nm), and silane coupling agent KH-550 are added to a high-speed mixer at a weight ratio of 1:1.6:0.03 and mixed for 20 min at a temperature of 85 °C and a stirring speed of 1200 r / min to obtain the composite nano-insulating modifier N-1.

[0046] Preparation Example 5

[0047] This preparation example is basically the same as Preparation Example 4, except that the weight ratio of nano boron nitride, nano alumina, and silane coupling agent is 1:1.2:0.01, and the compounding process is carried out at a temperature of 80℃, a stirring speed of 1500 r / min, and a mixing time of 15 min to obtain composite nano insulating modifier N-2.

[0048] Preparation Example 6

[0049] This preparation example is basically the same as Preparation Example 4, except that the weight ratio of nano boron nitride, nano alumina, and silane coupling agent is 1:2.0:0.05, and the compounding process is carried out at a temperature of 90℃, a stirring speed of 1000 r / min, and a mixing time of 25 min to obtain composite nano insulating modifier N-3.

[0050] III. Preparation of High-Temperature Resistant, Insulating, and Flame-Retardant Multifunctional Masterbatch

[0051] Example 1

[0052] This embodiment provides a high-temperature resistant, insulating, and flame-retardant multifunctional masterbatch, the components and weight parts of which are shown in Table 1. Specifically: the carrier resin is PA6 (relative viscosity 2.8); the core-shell microcapsule flame-retardant powder is M-1; the composite nano-insulating modifier is N-1; the dispersant is polyethylene wax; the antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a weight ratio of 1:1.2; and the compatibilizer is maleic anhydride-grafted polyolefin elastomer (POE-g-MAH, grafting rate 0.8%).

[0053] The preparation method is as follows:

[0054] (1) Premixing treatment: Weigh all components according to the weight parts, first put the carrier resin into a high-speed mixer, preheat it for 8 minutes at a speed of 800 r / min and a temperature of 80℃; then add the composite nano insulating modifier, dispersant and compatibilizer in sequence, mix at a low speed of 650 r / min for 8 minutes; finally add the core-shell microcapsule flame retardant powder and antioxidant, adjust the speed to 1300 r / min and raise the temperature to 100℃, mix for 30 minutes to obtain the premix.

[0055] (2) Melt blending extrusion: The premixed material is fed into a twin-screw extruder with a length-to-diameter ratio of 42:1, a screw speed of 350 r / min, and an extrusion pressure of 25 MPa. The temperatures of each section are set as follows: feeding section 180℃, melting section 230℃ and 240℃, homogenization section 245℃, and die head temperature 230℃. The twin-screw extruder uses a combined screw design, with 5 dispersing sections and 3 melting sections.

[0056] (3) Post-processing: The strands extruded by the twin-screw extruder are cooled by water at 30℃ and dried by air at a wind speed of 4m / s. After being granulated, they are sieved through a 6-mesh sieve and dried by hot air circulation at 100℃ for 5 hours. After drying, the moisture content of the masterbatch is ≤0.08%. After cooling to room temperature, a multifunctional masterbatch (denoted as C-1) is obtained.

[0057] Examples 2-5

[0058] The formulation composition (parts by weight) of Examples 2-5 (denoted as C-2 to C-5) is shown in Table 1, and the preparation method is the same as that of Example 1. In Example 2, the carrier resin is PBT; in Example 3, the dispersant is a silicone dispersant (Dow Corning MB50-002); in Example 4, the antioxidant is a mixture of antioxidant 1076 and antioxidant 168 in a weight ratio of 1:1.5; and in Example 5, the compatibilizer is glycidyl methacrylate-grafted polystyrene (PS-g-GMA). The masterbatch designations corresponding to Examples 2-5 are C-2 to C-5, respectively.

[0059] Table 1. Formulation composition (parts by weight) of Examples 1-5

[0060] Carrier resin 20 (PA6) 18 (PBT) 22 (PA6) 25 (PA6) 15 (PA6) Core-shell microcapsule flame retardant powder 48 (M-1) 45(M-2) 55 (M-1) 40 (M-3) 50 (M-2) Composite nano insulating modifier 15 (N-1) 18 (N-2) 12 (N-3) 22 (N-1) 20 (N-2) dispersant 8 7 10 6 9 antioxidants 4 5 3 4.5 3.5 compatibilizer 10 12 9 8 11

[0061] IV. Preparation of Comparative Masterbatch

[0062] To verify the technical effect of the present invention, the following comparative masterbatch was set up (formula shown in Table 2), and the preparation method was the same as in Example 1.

[0063] - Comparison with masterbatch D1: No microencapsulation was performed; the same core material mixture as M-1 (i.e., a physical blend of ammonium polyphosphate, melamine cyanurate, nano silica, and nano titanium dioxide) was used directly.

[0064] - Comparison with masterbatch D2: No composite nano-insulating modifier was added; only an equal amount of nano-alumina was used.

[0065] - Comparison with masterbatch D3: It does not contain nano-silica and nano-titanium dioxide from the core-shell microcapsule flame retardant powder; the core material is only ammonium polyphosphate and melamine cyanurate (weight ratio 1:0.3).

[0066] - Comparison with masterbatch D4: No antioxidants added.

[0067] - Comparison with masterbatch D5: It uses uncoated APP+MCA binary core material (without nano SiO2 and TiO2) and does not add composite nano insulating modifier (i.e. it lacks both of the core innovations of this invention).

[0068] Table 2 Comparison of Masterbatch Formulation Composition (parts by weight)

[0069] PA6 20 20 20 20 20 Uncoated core material mixture 48 - - - - M-1 - 48 48 48 48 N-1 15 - - 15 - Nano-alumina (unrefined) - 15 - - - Silicon-free titanium flame retardant powder (APP+MCA) - - 48 - - Uncoated APP + MCA (without silicon and titanium) - - - - 48 dispersant 8 8 8 8 8 antioxidants 4 4 4 - 4 compatibilizer 10 10 10 10 10

[0070] V. Application Example: Preparation of Insulators for High-Voltage Connectors

[0071] Examples 1-5 (C-1 to C-5) and comparative masterbatches D-1 to D-5 were mixed uniformly with PA66 (Pingdingshan Shenma EPR27) substrate resin for high-voltage connector insulators at a weight ratio of 30:70. The resulting mixture was then extruded and granulated with glass fiber (Jushi Group ECS10-03-568H, chopped length 3mm) at a weight ratio of 70:30 using a twin-screw extruder. The granulated material was then melt-injected to obtain high-voltage connector insulator test strips. The molding process parameters were: melt injection temperature 275℃, injection pressure 120MPa, mold temperature 85℃, and holding time 30s.

[0072] As a control (CK), test strips were prepared using a pure PA66 + 30% glass fiber blend without any added masterbatch, prepared using the same process.

[0073] VI. Performance Testing and Evaluation

[0074] The insulator samples prepared according to the aforementioned standards were subjected to performance tests, and the results are shown in Table 3.

[0075] Table 3 Performance test results of application example splines

[0076] C-1 <![CDATA[5.6×10¹ 5 ]]> 32.5 V-0 33.5 89 87 91 C-2 <![CDATA[5.2×10¹ 5 ]]> 31.8 V-0 32.8 87 85 89 C-3 <![CDATA[5.0×10¹ 5 ]]> 31.0 V-0 32.0 86 84 88 C-4 <![CDATA[5.8×10¹ 5 ]]> 33.1 V-0 34.2 91 88 93 C-5 <![CDATA[5.3×10¹ 5 ]]> 32.0 V-0 33.0 88 86 90 D-1 <![CDATA[1.2×10¹ 4 ]]> 18.5 V-1 25.0 45 52 38 D-2 <![CDATA[8.5×10¹ 4 ]]> 22.0 V-0 32.0 62 68 58 D-3 <![CDATA[3.8×10¹ 5 ]]> 28.5 V-1 27.5 72 70 65 D-4 <![CDATA[4.9×10¹ 5 ]]> 31.2 V-0 33.0 51 55 48 D-5 <![CDATA[2.0×10 13 ]]> 16.0 V-2 23.0 35 38 28 CK <![CDATA[8.0×10¹ 3 ]]> 15.0 V-2 22.0 35 40 30

[0077] 1 r r Volume resistivity retention rate after aging at 180℃ for 1000h

[0078] 2 r s Tensile strength (R) after aging at 180℃ for 1000 hours s Retention rate

[0079] 3 r R Volume resistivity retention rate after aging at 85℃ / 85%RH×1000h

[0080] VII. Results Analysis and Demonstration of Synergistic Effect

[0081] As shown in Table 3:

[0082] (I) Comprehensive performance advantages of the embodiments of the present invention

[0083] The masterbatch-modified PA66 / GF materials obtained in Examples 1-5 all have a volume resistivity ≥ 5.0 × 10¹ 5 The product exhibits a high strength (Ω·cm), a breakdown strength ≥31.0 kV / mm, a flame retardancy rating reaching UL94 V-0, a limiting oxygen index ≥32.0%, and maintains a volume resistivity and tensile strength ≥84% after 180℃×1000h heat aging. After 1000h high-temperature and high-humidity aging at 85℃ / 85% RH, the volume resistivity remains ≥88%. This demonstrates that the present invention achieves a unified combination of high insulation, high flame retardancy, high temperature resistance, and resistance to damp heat through the synergistic design of core-shell microcapsule flame-retardant powder and composite nano-insulating modifiers.

[0084] (II) Verification of the necessity of core-shell microcapsule encapsulation

[0085] Compared to D1 (uncoated core material), the insulation, flame retardant, and aging resistance properties of the microcapsule coating decreased significantly, especially the volume resistivity retention rate after high temperature and humidity aging, which was only 38%, far lower than the ≥88% of the example. This indicates that microcapsule coating effectively inhibits the hydrolytic migration of ammonium polyphosphate, which is key to ensuring the long-term stability of the material.

[0086] (III) Verification of the necessity of composite nano-insulating modifiers

[0087] The breakdown strength (22.0 kV / mm) and performance retention after aging of D2 (without the composite nano-insulating modifier, using only an equal amount of nano-alumina) were both lower than those of the example. This indicates that the combination of nano-boron nitride and nano-alumina in the composite nano-insulating modifier produces a synergistic enhancement effect—the plate-like structure of nano-boron nitride has a stronger blocking effect on charge carriers, while the particulate structure of nano-alumina is more conducive to filling free volume. The complementary physical barrier formed by the combination of the two is significantly better than that of a single filler.

[0088] (iv) Verification of the necessity of quaternary synergistic core materials (including Si and Ti)

[0089] Compared to D3 (flame-retardant core material without nano-silica and titanium dioxide), the flame retardant rating dropped to V-1, and the LOI decreased from ≥32% to 27.5%, with performance also worse than the example after aging. This verifies the necessity of a quaternary synergistic flame-retardant system composed of silicon, titanium, phosphorus, and nitrogen elements to improve flame retardant efficiency and overall heat resistance. In particular, although the volume resistivity of D3 is still relatively high (3.8×10¹), it still achieves better flame retardant performance. 5 The insulation performance was Ω·cm, but the flame retardant performance was not up to standard, indicating that high insulation alone is not the same as high flame retardancy. Only through quaternary synergistic design can the two be unified.

[0090] (V) Verification of the cross-component synergistic effect of flame-retardant microcapsules and insulating modifiers

[0091] Compared to D5 (which lacks both Si and Ti components in the quaternary core material and the composite nano-insulating modifier), the performance of D5 is comprehensively degraded, with a volume resistivity of only 2.0 × 10¹³ Ω·cm and a flame retardancy rating of V-2. In contrast, Example C-1, compared to D5, shows an approximately 280-fold increase in volume resistivity and a flame retardancy rating that rises from V-2 to V-0. More importantly, comparing the performance of D2 (which only has the insulating modifier but lacks the Si and Ti components in the microcapsules) and D3 (which only has the Si and Ti components in the microcapsules but lacks the insulating modifier): D2 has a flame retardancy rating of V-0 but a breakdown strength of only 22.0 kV / mm, while D3 has a breakdown strength of 28.5 kV / mm but a flame retardancy rating of only V-1. In embodiment C-1 of the present invention, both V-0 flame retardancy and 32.5 kV / mm breakdown strength are achieved, with performance far exceeding the simple sum of D2 and D3. This fully demonstrates that there is a real cross-component synergistic effect between the nano SiO2 / TiO2 in the flame retardant microcapsule and the nano BN / Al2O3 in the insulating modifier. Under combustion conditions, the two types of nanoparticles jointly participate in the construction of a dense inorganic-organic hybrid carbon layer, which not only improves the flame retardant efficiency but also protects the insulating structure.

[0092] (vi) The importance of the antioxidant system

[0093] Compared to D4 (without antioxidant), which showed acceptable initial performance, its performance deteriorated sharply after long-term thermal aging (the volume resistivity retention rate was only 51% after aging at 180℃). This indicates that the hindered phenol / phosphite binary antioxidant system is indispensable for achieving long-term temperature resistance of materials, and together with the inorganic physical barrier, it constitutes a dual chemical-physical anti-thermal aging mechanism.

[0094] (vii) The insulation, flame retardancy and temperature resistance of the control example (CK) are far lower than those of the embodiments of the present invention, highlighting the significant modification effect of the masterbatch of the present invention on the base resin.

[0095] In summary, the high-temperature resistant, insulating, and flame-retardant multifunctional masterbatch, its preparation method, and its application provided by this invention effectively solve the problem of simultaneously achieving insulation, flame retardancy, and temperature resistance in existing technologies. Furthermore, it exhibits good processing adaptability and significant modification effects, fully meeting the stringent requirements for high-voltage connector insulators in fields such as new energy vehicles and rail transit, and possesses extremely high industrial application value.

Claims

1. A high-temperature resistant, insulating, flame-retardant, multifunctional masterbatch, characterized in that, By weight, its components include: 15 to 25 parts of carrier resin, 40 to 55 parts of core-shell microcapsule flame retardant powder, 12 to 22 parts of composite nano insulating modifier, 6 to 10 parts of dispersant, 3 to 5 parts of antioxidant, and 8 to 12 parts of compatibilizer. The core-shell type microcapsule flame retardant powder uses melamine-formaldehyde resin as the shell layer and the core material is composed of ammonium polyphosphate, melamine cyanurate, nano silica, and nano titanium dioxide. The composite nano-insulating modifier is prepared by compounding nano-boron nitride, nano-alumina, and silane coupling agent in a high-speed mixer; Furthermore, the nano-silica and nano-titanium dioxide in the core-shell microcapsule flame retardant powder, together with the nano-boron nitride and nano-alumina in the composite nano-insulating modifier, jointly construct an inorganic nano-network structure in the polymer matrix, and jointly participate in the formation of the expanded char layer under combustion conditions.

2. The high-temperature resistant, insulating, flame-retardant, multifunctional masterbatch according to claim 1, characterized in that, The carrier resin is selected from polyamide 6 and polybutylene terephthalate.

3. The high-temperature resistant, insulating, flame-retardant, multifunctional masterbatch according to claim 1, characterized in that, The preparation method of the core-shell microcapsule flame retardant powder includes the following steps: S1. Core Material Pretreatment: Ammonium polyphosphate, melamine cyanurate, nano-silica, and nano-titanium dioxide are added to a high-speed mixer in a weight ratio of 1:(0.25 to 0.38):(0.2 to 0.3):(0.075 to 0.15). Water is added at 50 to 200 times the total weight of the powder. The mixture is stirred at high speed (600–1000 rpm) for 10 to 30 minutes. Then, a dilute ethanol solution of KH-550 is added, and the mixture is stirred at high speed for another 3 to 10 minutes. The molecular weight of the ammonium polyphosphate is ≥1000. The amount of KH-550 is 0.5% to 2% of the weight of the ammonium polyphosphate. S2. Melamine dispersion: Heat to 90-100℃, add melamine powder, and stir at high speed (600-1000 rpm) for 30-60 minutes; the melamine powder accounts for 5% to 10% of the weight of ammonium polyphosphate. S3. Add formaldehyde: Cool to 60-85℃, stir (400-800 rpm), adjust the pH of the system to 8-9 with hexamethylenetetramine or triethanolamine, and then slowly add formaldehyde solution (37% aqueous solution), react for 30-60 min; the amount of formaldehyde solution added should make the molar ratio of formaldehyde to melamine (2-12):1; S4. Polycondensation and coating: Cool to below 60℃, and slowly adjust the pH of the system to 4.5-6.5 with hydrochloric acid while stirring (400-800 rpm) for 30-60 minutes; S5. Curing and crosslinking: Cool to room temperature, filter, wash the filter cake with distilled water until neutral, heat to 90-100℃ and keep warm for 4 hours; heat to 115-125℃ and vacuum dry for 4 hours. S6. Crushing and sieving: Crush and sieve through a 200-325 mesh sieve to obtain a white powdery core-shell microcapsule flame retardant powder.

4. The high-temperature resistant, insulating, flame-retardant, multifunctional masterbatch according to claim 1, characterized in that, In the composite nano-insulating modifier, the particle size of nano-boron nitride and nano-alumina is 50nm to 180nm; the weight ratio of nano-boron nitride, nano-alumina, and silane coupling agent is 1:(1.2 to 2.0):(0.01 to 0.05); the silane coupling agent is KH-550 or KH-560; the compounding process is to mix for 15-25 minutes at a temperature of 80-90℃ and a stirring speed of 1000-1500r / min.

5. The high-temperature resistant, insulating, flame-retardant, multifunctional masterbatch according to claim 1, characterized in that, The dispersant is one or more of polyethylene wax, polypropylene wax, fatty acids and their metal soaps, fatty acid esters, and silicone dispersants; the antioxidant is a binary compound of hindered phenolic antioxidants and phosphite antioxidants, with a compound weight ratio of 1:(1-1.5); the compatibilizer is one or more of maleic anhydride grafted compatibilizers and glycidyl methacrylate grafted compatibilizers.

6. A method for preparing a high-temperature resistant, insulating, flame-retardant, multifunctional masterbatch as described in any one of claims 1 to 5, characterized in that, Includes the following steps: (1) Premixing treatment: Weigh all components according to the weight parts, first put the carrier resin into a high-speed mixer, preheat it for 6 min to 9 min at a speed of 700 to 900 r / min and a temperature of 75℃ to 85℃, then add the composite nano insulating modifier, dispersant and compatibilizer in sequence, mix at a speed of 550 to 750 r / min for 6 min to 9 min, and finally add the core-shell microcapsule flame retardant powder and antioxidant, adjust the speed to 1200 to 1500 r / min and raise the temperature to 90℃ to 110℃, mix for 20 min to 35 min to obtain the premix; (2) Melt blending and extrusion: The premixed material is fed into a twin-screw extruder with a length-to-diameter ratio of 40:1 to 45:1, a screw speed of 250 to 500 r / min, an extrusion pressure of 20 MPa to 30 MPa, and the temperature of each section is set as follows: feeding section 170℃ to 190℃, melting section 210℃ to 250℃, homogenization section 230℃ to 250℃, and die head temperature 220℃ to 240℃ for melt blending and extrusion; the twin-screw extruder adopts a combined screw and is equipped with 5 to 6 dispersing sections and 2 to 3 melting sections; (3) Post-processing: The strands extruded by the twin-screw extruder are water-cooled at 25℃ to 40℃ and air-dried at a wind speed of 3m / s to 5m / s. After being granulated, they are sieved through a 4-mesh to 8-mesh sieve and dried with hot air circulation at 90℃ to 110℃ for 4h to 6h. After drying, the moisture content of the masterbatch is ≤0.08%. After cooling to room temperature, the high temperature resistant, insulating, flame retardant, and multifunctional masterbatch is obtained.

7. The application of a high-temperature resistant, insulating, flame-retardant, multifunctional masterbatch as described in any one of claims 1 to 5 in the insulator of a high-voltage connector, characterized in that, The application method is as follows: the high temperature resistant, insulating, flame retardant, multifunctional masterbatch is mixed with the substrate resin for high voltage connector insulators at a weight ratio of (20 to 35): (65 to 80), and the resulting mixture is then extruded and granulated with glass fiber at a weight ratio of 70:30 using a twin-screw extruder. After melt injection molding, the high voltage connector insulator is prepared.

8. The application according to claim 7, characterized in that, The substrate resin for the high-voltage connector insulator is one of polyamide 66 and polybutylene terephthalate; the molding process parameters are: melt injection temperature 230℃ to 300℃, injection pressure 80MPa to 160MPa, mold temperature 70℃ to 100℃, and holding time 12s to 120s.