A pole frame insulation composite material and a preparation method thereof

Abstract

The application belongs to the technical field of polymer composites, and particularly relates to a polar frame insulation composite material and a preparation method. The polar frame insulation composite material comprises polyphenylene sulfide resin, surface modified reinforcing fiber, composite insulation filler, interface compatibilizer and composite anti-aging agent. The composite insulation filler is composed of graded micro-sized insulation particles and nano-sized insulation particles, and a multi-scale charge trap network is constructed in the matrix. The application also introduces a piezoelectric ceramic functional regulation filler, uses internal residual stress generated by integrated injection molding for in-situ pre-polarization, and actively suppresses local electric field peaks. The preparation method comprises raw material pretreatment, filler premixing modification, melt blending extrusion, stress relief annealing and integrated injection molding. Through interface chemical bonding and multi-scale structure synergy, the polar frame insulation composite material is systematically improved in terms of high dielectric strength, high mechanical property and chemical corrosion resistance.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite materials technology, specifically relating to a pole frame insulating composite material and its preparation method. Background Technology

[0002] As a key component of core equipment such as battery plates and electrolytic cells, the reliability of the electrode frame under complex operating conditions has become a bottleneck restricting the overall performance improvement of related systems. The electrode frame not only needs to bear high-intensity mechanical support tasks, but also must maintain excellent insulation performance and structural integrity under multi-physical field coupling environments such as strong acid and alkali corrosive liquids, extremely high voltage electric fields, and frequent fluctuating thermal cycling stress. This places extremely high demands on the bulk physicochemical properties of the electrode frame material.

[0003] The invention patent CN1216430C, authorized by patent number CN1216430C, proposes an electrode frame with a lead foil-supported grid structure made of polymer-based composite materials. The aim is to improve the stiffness of the electrode assembly by leveraging the high modulus of the composite material and to utilize the inherent resistance of the polymer to chemical corrosion. This solution addresses the insufficient corrosion resistance of traditional metal electrode frames to some extent and represents an important attempt at the evolution of electrode frame materials towards composite materials. However, this type of technology still has limitations in the formulation design and molding process of the composite material. During the preparation process, the wettability and dispersion uniformity between the insulating functional filler and the polymer matrix are difficult to control precisely, leading to the easy formation of microscopic heterogeneous regions within the material. Under the action of an ultra-high voltage electric field, these unevenly distributed charge regions can cause severe electric field distortion, thereby inducing partial discharge or dielectric breakdown. Furthermore, this solution fails to adequately address the problem of interfacial stress attenuation caused by chemical medium penetration during long-term service of the electrode frame material, raising questions about the long-term operational reliability of the material.

[0004] To enhance insulation protection in specific areas, the prior art (CN205398429U) adopts an alternative approach: introducing rubber or epoxy resin insulation layers at specific locations on the electrode frame through coating or bonding. This split-type structural design can provide significant electrical isolation in the short term, and the process implementation path is relatively straightforward. However, the non-integrated molding characteristic exposes its inherent vulnerability when facing the increasingly severe mechanical shocks and high-voltage coupling stresses of modern industry. Due to the mismatch in thermal expansion coefficients between the insulation coating and the substrate material, as well as the physical limitations of interfacial adhesion, stress concentration often occurs at the interface after frequent elastic compression or pressure fluctuations, leading to localized peeling, cracking, or even complete detachment of the insulation layer. Furthermore, the split-type processing not only significantly increases the complexity of the manufacturing process but also greatly reduces the quality consistency of products in large-scale production due to fluctuations in coating thickness and bonding strength between batches.

[0005] Under the dual stress of strong corrosion and high-voltage electric fields, any microscopic defects or weak points within a material will be amplified infinitely by the superposition of multiple physical fields, ultimately leading to insulation failure or structural collapse. Existing modification methods often focus on improving performance in a single dimension, neglecting the trade-off between insulation performance, mechanical strength, and interfacial stability. For example, simply increasing the load of insulating filler often sacrifices the material's processing fluidity and impact toughness; while simple external coating cannot solve the deep-seated interfacial compatibility problem. This current technological status quo makes existing electrode frame materials exhibit insurmountable theoretical bottlenecks when facing the stringent requirements of long lifespan and high voltage tolerance in cutting-edge fields such as ultra-large-scale energy storage and high-performance electrolytic hydrogen production. Summary of the Invention

[0006] This invention discloses a pole frame insulating composite material and its preparation method, in order to solve the technical problems of insufficient insulation reliability, interface peeling, uneven micro electric field distribution and poor long-term stability of pole frame materials under strong acid and alkali, high voltage electric field and complex stress coupling conditions.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing a pole frame insulating composite material includes the following steps:

[0009] The first step is to dry the polyphenylene sulfide resin at 120°C to 140°C for 4 to 6 hours until the moisture content is less than 0.02%; the surface-modified reinforcing fibers and composite insulating fillers are dried at 100°C for 3 hours respectively.

[0010] The second step involves putting the dried composite insulating filler into a high-speed mixer and preheating it to 80°C at a speed of 1500 rpm to 2000 rpm. Then, an organic titanate coupling agent solution of 1.0% to 1.5% of the filler mass is added, and the mixture is stirred continuously for 20 to 30 minutes.

[0011] The third step involves feeding the pretreated polyphenylene sulfide resin, interface compatibilizer, composite anti-aging agent, and modified composite insulating filler into a twin-screw extruder through the main feed port, and feeding the surface-modified reinforcing fiber through the side feed port, followed by melt blending extrusion. The twin-screw extruder has a length-to-diameter ratio (L / D) of 40:1 to 48:1, and the extrusion process is divided into ten heating zones. The temperatures of the first to tenth zones are set as follows: 265℃-275℃, 285℃-295℃, 300℃-310℃, 305℃-315℃, 305℃-315℃, 300℃-310℃, 295℃-305℃, 290℃-300℃, 285℃-295℃, and 280℃-290℃, respectively. The screw speed is set to 350 rpm to 500 rpm, and the die head pressure is controlled at 5 MPa to 8 MPa.

[0012] The fourth step involves cooling the extruded strip in a constant temperature water bath at 60°C to 80°C, followed by air drying and pelletizing to obtain composite material particles. The composite material particles are then subjected to stress-relief annealing at 140°C for 2 hours. The fifth step involves feeding the annealed composite material particles into an injection molding machine and performing integrated injection molding of the pole frame at a barrel temperature of 290°C to 320°C, an injection pressure of 80MPa to 120MPa, and a mold temperature of 130°C to 150°C. The holding pressure time is set to 15 to 25 seconds, and the cooling time is set to 30 to 50 seconds.

[0013] Furthermore, the polyphenylene sulfide resin adopts a linear polymer structure, with a weight-average molecular weight of 45,000 to 55,000, a melt viscosity of 150 Pa·s to 200 Pa·s at 315°C, a melt index of 30 g / 10 min to 50 g / 10 min, and a sodium ion mass fraction of less than 50 ppm.

[0014] Furthermore, the surface-modified reinforcing fiber is an alkali-free glass fiber or basalt fiber that has been surface-treated with a silane coupling agent, with a length of 3 mm to 6 mm and a single filament diameter of 10 μm to 13 μm; the silane coupling agent is γ-aminopropyltriethoxysilane or γ-(2,3-epoxypropoxy)propyltrimethoxysilane, with a coating amount of 0.8% to 1.2% of the fiber mass.

[0015] Furthermore, the composite insulating filler is composed of micron-sized insulating particles and nano-sized insulating particles in a mass ratio of 3:1 to 5:1; the micron-sized insulating particles are selected from one or more of calcined kaolin, molten silica, or aluminum nitride particles, with an average particle size D50 of 5 μm to 12 μm; the nano-sized insulating particles are hexagonal boron nitride or nano-titanium dioxide, with an average particle size D50 of 50 nm to 150 nm; the composite insulating filler undergoes liquid-phase coating modification treatment, and its surface is coated with an organic titanate coupling agent film layer, the thickness of which is 3 nm to 8 nm.

[0016] Furthermore, the interface compatibilizer is maleic anhydride-grafted polyphenylene sulfide with a grafting rate of 0.8% to 1.5%; the composite anti-aging agent is composed of hindered phenolic antioxidant 1010 and phosphite antioxidant 168 in a mass ratio of 1:1 to 1:2.

[0017] Furthermore, the particle size distributions of the micron-sized insulating particles and the nano-sized insulating particles satisfy the following spatial geometry filling model:

[0018]

[0019] in, The maximum volume fraction of the nanoscale insulating particles is dimensionless. The volume fraction of the micron-sized insulating particles is dimensionless. The average radius of the nanoscale insulating particles is given in units of 1. ; The average radius of the micron-sized insulating particles is given in units of . ;and ; This is the space ratio coefficient for a single sphere in the closest packing of spheres of equal diameter. This refers to the porosity when spheres of equal diameter are packed most densely, and it is dimensionless. The spatial geometric filling model is used to determine the ratio range of micron-sized insulating particles to nano-sized insulating particles, and the actual ratio is adjusted within ±20% of the value calculated by the model.

[0020] Furthermore, the sodium ion mass fraction in the polyphenylene sulfide resin is less than 50 ppm, and the weight-average molecular weight is 45,000 to 55,000. By combining the low-sodium-ion content polyphenylene sulfide resin with micron-sized and nano-sized insulating particles graded in a mass ratio of 3:1 to 5:1, multi-scale charge traps are formed at the matrix-filler interface, increasing the trap density enhancement factor. satisfy:

[0021]

[0022] in, The trap density enhancement factor is dimensionless. The trap density in the composite material, in units of ; The trap density of the pure polyphenylene sulfide matrix is ​​expressed in units of... ; This is an empirical constant related to the surface activity of the packing material. It is dimensionless and ranges from 0.8 to 1.2. Its specific value is determined by the BET specific surface area of ​​the packing material. The decision satisfies the empirical relation. ,in The BET specific surface area of ​​the composite insulating filler is given in units of... ; The volume fraction of micron-sized insulating particles, dimensionless; The volume fraction of nanoscale insulating particles, dimensionless; The volume fraction of the polyphenylene sulfide matrix is ​​dimensionless and satisfies the following conditions: ; is the average dielectric constant of the composite insulating filler, which is dimensionless; The dielectric constant of the polyphenylene sulfide matrix is ​​dimensionless; by... By controlling the value between 3.5 and 5.2, the charge migration rate is reduced to less than 20% of that of pure polyphenylene sulfide matrix.

[0023] Furthermore, during the melt blending process in the third step, the degree of interfacial reaction between the polyphenylene sulfide matrix and the interfacial compatibilizer... Over time The change satisfies the following second-order reaction model:

[0024]

[0025] in, The degree of interfacial reaction is dimensionless; Reaction time, in units of ; The reaction rate constant is expressed in units of 1000 m / s. ; With temperature The relationship conforms to the Arrhenius equation ,in Pre-exponential factors, in units of ; Activation energy, unit: ; Let be the ideal gas constant, and take the value of . ; Absolute temperature, unit: Regarding the maleic anhydride-grafted polyphenylene sulfide and matrix system described in this invention, measurements were taken using non-isothermal differential scanning calorimetry (DSC). for to , orders of magnitude By controlling the temperature of the shearing section to be maintained between 305℃ and 315℃, Value at to Between, degree of reaction The extrusion residence time reaches 0.92 or higher.

[0026] Furthermore, during the injection molding process in the fifth step, the crystallization kinetics of polyphenylene sulfide are described by the following Avrami equation:

[0027]

[0028] in, Let be the relative crystallinity at time t, which is dimensionless; Crystallization time, in units of ; This is the crystallization rate constant, in units of... ; The Avrami index is dimensionless; the mold temperature is controlled between 130℃ and 150℃ to achieve this. Maintain at to ,and The value is between 2.5 and 3.0, which makes the crystallinity difference between different parts of the polar frame less than 3%.

[0029] Furthermore, in the third step, the melt blending process employs a multi-stage vacuum exhaust system, with exhaust ports of vacuum levels ranging from -0.08 MPa to -0.095 MPa set in the sixth and eighth zones of the extruder, respectively, to reduce the internal porosity of the material to less than 0.1%.

[0030] Furthermore, in the stress-relief annealing process of the fourth step, the secondary crystallization kinetics of polyphenylene sulfide are described using the following modified Avrami model:

[0031]

[0032] in, The increase in crystallinity during annealing is dimensionless. The final increase in crystallinity after annealing is dimensionless; This is the secondary crystallization rate constant, in units of... ; The growth index is dimensionless. Annealing time, in units of Under isothermal annealing conditions at 140℃ for 2 hours, The value ranges from 0.08 to 0.12. for This increases the overall crystallinity of the material by 5% to 8%.

[0033] Furthermore, in the fifth step, the mold surface is coated with a polytetrafluoroethylene anti-stick layer with a thickness of 10μm to 20μm, and an infrared temperature monitoring and compensation system is provided in the mold cavity to ensure that the temperature fluctuation during the electrode frame molding process is controlled within ±2℃.

[0034] Furthermore, in the fifth step, sequential valve hot runner technology is used to achieve smooth filling of the melt by controlling the opening time difference of multiple gates, thereby eliminating weld lines.

[0035] Furthermore, a nucleating agent comprising 0.1% to 0.3% of the matrix mass is added to the composite material to adjust the crystallization rate constant at 290°C. Controlled to The average diameter of the spherulites formed It has a fine spherulitic structure ranging from 5 μm to 10 μm, with a tortuosity factor Defined as:

[0036]

[0037] in, The tortuosity factor is dimensionless. The average diameter of the spherulites is given in units of 1. ; The thickness of the interface layer between the crystalline and amorphous regions, in units of... The value ranges from 0.1 μm to 0.3 μm; and These represent the interface areas of the crystalline and amorphous regions, respectively, in units of... The ratio depends on the crystal morphology of the material; it can be controlled by nucleating agents. The thickness of polyphenylene sulfide (PPS) was reduced from 15μm-25μm to 5μm-10μm, making it possible to achieve the desired results. Improved from 1.2-1.4 to 1.8-2.2.

[0038] Furthermore, the composite material also includes a functionally modulating filler, which is a piezoelectric ceramic particle with the general chemical formula [insert chemical formula here]. The piezoelectric ceramic particles have a perovskite structure selected from one or more of lead zirconate titanate, barium titanate, or potassium sodium niobate, and the average particle size D50 is 200 nm to 800 nm, with a piezoelectric coefficient of [missing information]. The functional control filler comprises 3 to 10 parts by mass in the composite material and forms a multi-scale gradation structure with the micron-sized and nano-sized insulating particles, wherein the piezoelectric ceramic particles are distributed in the gap region between the micron-sized and nano-sized particles; the surface of the functional control filler is coated with an insulating coupling agent layer, which is an organic titanate coupling agent with a coating thickness of 2 nm to 5 nm.

[0039] Furthermore, in the fifth step of the integrated injection molding process, a pressure sensor is installed inside the mold cavity to monitor the internal stress generated by material shrinkage during the forming of the pole frame in real time. The internal stress and the polarization intensity of the piezoelectric ceramic particles satisfy the following relationship:

[0040]

[0041] in, For piezoelectric ceramic particles under internal stress The polarization intensity produced under the action, in units of ; piezoelectric coefficient, unit: ,in ; The internal residual stress of the pole frame after demolding, in units of By controlling the injection holding pressure and cooling rate, the residual material inside the electrode frame after demolding is reduced. Within the range of 5 MPa to 15 MPa, this residual stress causes the piezoelectric ceramic particles to be pre-polarized along a direction perpendicular to the electric field. Consequently, during the service life of the electrode frame, when an external electric field is applied... When applied to composite materials, the built-in electric field generated by piezoelectric ceramic particles satisfy:

[0042]

[0043] in, Let be the vacuum permittivity, and take the value of . ; The relative permittivity of the piezoelectric ceramic particles is dimensionless; it can be adjusted... With piezoelectric ceramic particles , making and The directions are opposite, and achieve It reduces the electric field intensity by 5% to 15%, thereby offsetting local electric field spikes in situ and improving the uniformity of electric field distribution on the pole frame surface by more than 30%.

[0044] In addition, the present invention also discloses a pole frame insulating composite material, which is prepared by the method described above for preparing the pole frame insulating composite material.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] This invention constructs a continuous and dense multi-scale insulating network within a polyphenylene sulfide (PPS) matrix by precisely proportioning micron-sized and nano-sized insulating particles and optimizing the particle size distribution using a spatial geometric filling model. This allows the nanoparticles to accurately fill the voids formed by the accumulation of micron-sized particles. This structure creates a high-density charge trap within the material, significantly extending the charge migration path and fundamentally suppressing charge transport and partial discharge under high-voltage electric fields, thereby greatly enhancing the bulk insulation strength and breakdown field strength of the electrode frame.

[0047] This invention solves the interfacial reliability problem of traditional electrode frames through interfacial chemical bonding and integrated molding processes. Maleic anhydride-grafted polyphenylene sulfide (PPS) is used as an interfacial compatibilizer, establishing strong covalent bonding centers between the PPS matrix, reinforcing fibers, and insulating fillers, eliminating microscopic gaps in the physical bonding. Simultaneously, this invention employs an integrated injection molding process, replacing the existing split coating structure, fundamentally avoiding the risk of peeling and cracking caused by mismatched thermal expansion coefficients at heterogeneous interfaces. Through precise control of crystallization kinetics and annealing processes, the crystallinity difference across different parts of the electrode frame is minimal, and the internal stress is uniform, ensuring the physical integrity of the insulation layer and matrix under complex thermal cycling and mechanical impact conditions.

[0048] This invention introduces piezoelectric ceramic particles into a composite material and utilizes the internal residual stress generated during the integral molding of the electrode frame to pre-polarize the piezoelectric particles in situ. During service, the piezoelectric particles spontaneously generate a built-in electric field opposite to the direction of the applied electric field under the action of an external electric field, actively canceling local electric field spikes, suppressing electric field distortion at the source, significantly improving the partial discharge initiation voltage and breakdown field strength, and enabling the electrode frame to have active electric field control capability.

[0049] This invention, through the synergistic design of a low-sodium-content polyphenylene sulfide matrix, surface-modified reinforcing fibers, multi-scale insulating fillers, piezoelectric functional fillers, and interfacial compatibilizers, combined with precision process control such as vacuum degassing, sequential valve hot runners, and infrared temperature control, enables the electrode frame insulating composite material to simultaneously possess high dielectric strength, high mechanical properties, excellent chemical corrosion resistance, and thermal stability. The electrode frame prepared by this invention can readily withstand the harsh service environments of strong acids and alkalis, high-voltage electric fields, and complex thermo-mechanical couplings, providing key component support for high-performance energy storage and electrolytic hydrogen production equipment, and possessing extremely high industrial application value and long-term service safety. Attached Figure Description

[0050] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0051] Figure 1 This is a flowchart of the overall process of the method described in this invention.

[0052] Figure 2 This is a simplified flowchart of the melt blending extrusion step of the present invention. Detailed Implementation

[0053] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the embodiments of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0054] The following is in conjunction with the appendix Figures 1-2 The embodiments of the present invention will be described in detail below.

[0055] This invention discloses a pole frame insulating composite material and its preparation method. By precisely controlling the microscopic physicochemical properties of the matrix resin, the surface functionalization modification of the reinforcing phase, and the gradient distribution of the filling phase, the system-level stability of the material under extremely complex working conditions is achieved.

[0056] In a specific embodiment of the present invention, polyphenylene sulfide resin serves as the continuous matrix phase of the composite material. The selection of its basic physical properties directly determines the geometric stability and electrical substrate of the electrode frame under high-temperature and highly corrosive environments. The polyphenylene sulfide resin used has a highly ordered linear polymer structure, which endows the material with extremely high crystallinity, thereby enhancing its resistance to chemical penetration.

[0057] The mass fraction of polyphenylene sulfide resin is limited to 45 to 55 parts to ensure that the system still has good melt flowability after the introduction of a high proportion of reinforcing fibers and insulating fillers.

[0058] Specifically, the melt index of polyphenylene sulfide resin is controlled between 30 g / 10 min and 50 g / 10 min, which is based on the balance between melt filling pressure drop and molecular chain orientation during complex electrode frame injection molding.

[0059] Furthermore, the polyphenylene sulfide resin has a weight-average molecular weight distribution between 45,000 and 55,000, and its melt viscosity at 315°C is maintained between 150 Pa·s and 200 Pa·s, which is beneficial for achieving effective dispersion of micro and nanoparticles in the high shear field of twin-screw extrusion.

[0060] To meet the stringent insulation requirements under high-voltage electric fields, this polyphenylene sulfide resin undergoes a deep ion removal process, reducing the mass fraction of sodium ions within it to below 50 ppm. This low ion content significantly suppresses dielectric losses and potential electrochemical breakdown risks caused by ion migration under DC high-voltage cycling conditions.

[0061] The surface-modified reinforcing fibers selected in this invention serve a dual purpose in the system: providing mechanical support and interfacial insulation shielding. The reinforcing fibers comprise 20 to 30 parts by weight, with a finely defined monofilament diameter of 10 to 13 μm and an initial fiber length controlled between 3 mm and 6 mm. This aspect ratio, combined with the specific twin-screw shear strength described later, ensures that the fiber length retained in the final molded part remains within the effective reinforcement range of 0.4 mm to 0.8 mm.

[0062] The surface of the reinforcing fiber is subjected to directional chemical treatment with a silane coupling agent. The silane coupling agent is selected from γ-aminopropyltriethoxysilane or γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and its coating amount is strictly controlled between 0.8% and 1.2% of the fiber mass. Under these process conditions, the hydrolytic groups of the silane molecules undergo a condensation reaction with the hydroxyl groups on the fiber surface to form strong siloxane covalent bonds, while its organic functional groups react in situ with the polyphenylene sulfide matrix or interface compatibilizer during subsequent high-temperature blending. This cross-interfacial chemical bonding not only eliminates the microscopic gaps present in the physical-mechanical bonding but also constructs a dense passivation film on the surface of the reinforcing fiber, effectively preventing electrolyte creep and leakage along the fiber axis.

[0063] This invention introduces a composite insulating filler composed of micron-sized and nano-sized insulating particles, with a total mass fraction of 15 to 22 parts. These two types of fillers with different spatial scales are graded in a mass ratio of 3:1 to 5:1. Micron-sized particles (such as calcined kaolin, fused silica, or aluminum nitride with an average particle size D50 of 5 μm to 12 μm) construct a large-scale insulating framework within the matrix, while nano-sized particles (such as hexagonal boron nitride or nano-titanium dioxide with an average particle size D50 of 50 nm to 150 nm) fill the geometric gaps between the micron-sized particles and the free volume of the polymer chain segments. This close-packed structure significantly increases the charge trap density within the composite material.

[0064] The effective dielectric constant of the composite material follows a negative feedback tuning model based on the Maxwell-Wagner effect, which is achieved by adjusting the volume fraction of nanoparticles. Volume fraction of micron-sized particles This makes the effective dielectric constant of the composite system Maintaining high consistency across the entire domain, the local dielectric constant fluctuation gradient is strictly controlled below 0.05 / μm, thereby suppressing the partial discharge phenomenon caused by electric field distortion at the physical source.

[0065] To further optimize the wettability between the filler and the matrix, the composite insulating filler underwent liquid-phase coating modification. At a specific temperature, an insulating organic film layer with a thickness of only 3nm to 8nm was formed on the filler surface using an organotitanate coupling agent. This nanoscale film layer has a dual function: on the one hand, its hydrophobic long-chain structure can significantly reduce the hydrophilicity of the filler surface, preventing environmental moisture from accumulating at the filler interface and forming conductive pathways; on the other hand, the organotitanate coupling agent chelate can act as an internal lubricant in the molten state, improving the processing fluidity of the high-filler system.

[0066] In terms of deep interfacial compatibility construction, maleic anhydride-grafted polyphenylene sulfide (PPS) at a mass ratio of 2 to 4 parts was used as an interfacial compatibilizer. The grafting rate of this compatibilizer was set between 0.8% and 1.5%, an optimized range validated through extensive experiments. Too low a grafting rate would not provide sufficient chemical bonding sites, while too high a grafting rate might lead to degradation of the PPS backbone. These grafted maleic anhydride groups can undergo in-situ ring-opening addition reactions with coupling agent molecules on the surface of the reinforcing fibers and hydroxyl groups on the surface of the composite filler, establishing a high-strength molecular bridge between the matrix and the reinforcing and filling phases. The construction of this interfacial structure enables uniform load transfer when the material is subjected to high-voltage electrolyte pressure and fastening stress, avoiding stress concentration that could lead to interfacial delamination.

[0067] To ensure the material's antioxidant properties during long-term service, 0.5 to 1.2 parts of a composite anti-aging agent are added to the system. The anti-aging system consists of hindered phenolic antioxidant 1010 and phosphite antioxidant 168 in a mass ratio of 1:1 to 1:2. At processing temperatures above 300°C, the hindered phenolic antioxidant acts as the primary antioxidant to capture peroxide groups, while the phosphite antioxidant acts as an auxiliary antioxidant to decompose hydrogen peroxides. The synergistic effect of the two effectively prevents the breakage of polyphenylene sulfide molecular chains under high-temperature processing and long-term thermo-oxidative aging environments.

[0068] The preparation process of the electrode frame insulation composite material described in this invention firstly involves the following steps in the raw material pretreatment stage: the polyphenylene sulfide resin must undergo dehydration treatment in a forced-air drying oven at 120°C to 140°C for 4 to 6 hours until the moisture content is below 0.02%. This indicator is a crucial prerequisite for preventing hydrolytic degradation of polyphenylene sulfide in the high-temperature molten state and ensuring that its mechanical strength does not degrade. Simultaneously, the surface-modified reinforcing fibers and composite insulating fillers also need to be dried at 100°C for 3 hours to eliminate adsorbed water.

[0069] In the filler premixing and modification step, the dried composite insulating filler is fed into a high-speed mixer at a speed of 1500 rpm to 2000 rpm. Frictional heating preheats the material to 80°C, and a precisely metered organic titanate coupling agent solution (1.0% to 1.5% of the filler mass) is sprayed in atomized form. Under vigorous stirring for 20 to 30 minutes, the coupling agent molecules achieve monomolecular-level coating on the filler surface, forming a hydrophobic insulating layer that lays the foundation for subsequent uniform dispersion.

[0070] This embodiment employs a twin-screw extruder with a length-to-diameter ratio (L / D) of 40:1 to 48:1. The screw assembly utilizes an optimized combination of interlocking screw elements with strong shearing capabilities and dispersing screw elements with high dispersion capabilities. The length of the shearing section is set to 25% to 30%. The extruder's ten heating zones are set as follows: Zone 1 265℃-275℃, Zone 2 285℃-295℃, Zone 3 300℃-310℃, Zone 4 305℃-315℃, Zone 5 305℃-315℃, Zone 6 300℃-310℃, Zone 7 295℃-305℃, Zone 8 290℃-300℃, Zone 9 285℃-295℃, and Zone 10 280℃-290℃. This stepped temperature profile ensures controlled thermal processes of the resin from melting to mixing to degassing. To completely eliminate low-molecular-weight volatiles in the material, exhaust ports with vacuum levels ranging from -0.08 MPa to -0.095 MPa were installed in zones six and eight, resulting in an internal porosity of less than 0.1% in the final material. The screw speed was maintained at 350 rpm to 500 rpm, coupled with a die head pressure of 5 MPa to 8 MPa, ensuring the retention of the reinforcing fiber length in the melt and the highly homogeneous distribution of the micro- and nano-fillers.

[0071] The extruded strips are cooled in a constant-temperature water bath at 60°C to 80°C, and then air-dried and pelletized to obtain composite material particles. These particles are then subjected to stress-relief annealing at 140°C for 2 hours to induce secondary rearrangement of the polyphenylene sulfide molecular chains. Studies have shown that this annealing process can further increase the heat distortion temperature of the material by 15°C to 20°C and significantly improve the dimensional stability of the material.

[0072] In the final integrated molding stage, the annealed granules are molded in an injection molding machine at a barrel temperature of 290℃ to 320℃ and an injection pressure of 80MPa to 120MPa. The mold temperature is controlled at 130℃ to 150℃ to ensure that the polyphenylene sulfide reaches optimal crystallinity. A 10μm to 20μm polytetrafluoroethylene anti-stick layer is applied to the mold surface, and combined with an infrared temperature monitoring and compensation system, the temperature fluctuation within the mold cavity is controlled within ±2℃. By employing sequential valve hot runner technology, the opening time of multiple gates is precisely controlled, completely eliminating weld lines in the injection molded parts and achieving a target of greater than 99% consistency in the all-around electrical insulation performance of the frame.

[0073] To facilitate a better understanding of the present invention by those skilled in the art, the present invention will be further illustrated below with reference to specific implementation examples.

[0074] Example 1: By weight, 52 parts of polyphenylene sulfide resin (melt index 35 g / 10 min, weight average molecular weight 52000, sodium ion content 35 ppm), 24 parts of alkali-free glass fiber (diameter 11 μm, length 4.5 mm, treated with γ-aminopropyltriethoxysilane), 18 parts of composite insulating filler (molten silica to hexagonal boron nitride mass ratio 4:1, micron D50=8 μm, nanon D50=80 nm, organic titanate coupling agent coating thickness 5 nm), 4 parts of maleic anhydride-grafted polyphenylene sulfide (grafting rate 1.2%), and 1 part of composite anti-aging agent (1010:168=1:1.5). Following the aforementioned preparation method, the extrusion speed was 450 rpm, the injection mold temperature was 145℃, and the holding pressure was 20 seconds.

[0075] Example 2: By weight, the following were used: 48 parts of polyphenylene sulfide resin (melt index 42 g / 10 min, weight average molecular weight 48000, sodium ion content 22 ppm), 26 parts of alkali-free glass fiber (diameter 11 μm, length 5 mm, treated with γ-aminopropyltriethoxysilane, coating amount 1.0%), 20 parts of composite insulating filler (aluminum nitride to hexagonal boron nitride mass ratio 4:1, micron D50=7 μm, nanon D50=70 nm, organic titanate coupling agent coating thickness 6 nm), 4 parts of maleic anhydride grafted polyphenylene sulfide (grafting rate 1.3%), 1 part of composite anti-aging agent (1010:168=1:1.2), and 0.2 parts of nucleating agent talc.

[0076] The preparation process is as follows:

[0077] The first step is raw material pretreatment: polyphenylene sulfide resin is dried at 135℃ for 5 hours with a moisture content of 0.015%; surface-modified reinforcing fibers and composite insulating fillers are dried at 100℃ for 3 hours respectively.

[0078] The second step is filler premixing modification: the dried composite insulating filler is put into a high-speed mixer and preheated to 80°C at 1800 rpm. An organic titanate coupling agent solution accounting for 1.3% of the filler mass is added and stirred continuously for 25 minutes.

[0079] The third step is melt blending extrusion: the twin-screw extruder has an L / D ratio of 44:1, the shearing zone length in the screw assembly accounts for 28% of the effective screw length, and the temperatures of the ten heating zones are set as follows: 270℃, 290℃, 305℃, 310℃, 310℃, 305℃, 300℃, 295℃, 290℃, and 285℃; the screw speed is 420 rpm, and the die pressure is 6.5 MPa; the vacuum levels in zones six and eight are set at -0.09 MPa and -0.092 MPa, respectively; the shear rate is controlled by adjusting the screw speed and feed rate. Maintain at Duration of stay The reaction time is 75 seconds. The particle size reaches 0.95. The fourth step is granulation and post-processing: the extruded strips are cooled in a 70℃ constant temperature water bath, air-dried and granulated, and then subjected to stress-relief annealing at 140℃ for 2 hours.

[0080] Step 5, integrated molding: The annealed composite material particles are fed into the injection molding machine. The barrel temperature is 305℃, the injection pressure is 100MPa, the mold temperature is 140℃, the holding time is 20 seconds, and the cooling time is 40 seconds. The mold surface is coated with a 15μm polytetrafluoroethylene anti-stick layer. The infrared temperature monitoring and compensation system controls the temperature fluctuation of the mold cavity to ±1.5℃. The sequential valve hot runner technology is used to control the opening of the four gates in sequence, with an opening time difference of 0.2 seconds.

[0081] Example 3: By weight, the following components were used: 52 parts polyphenylene sulfide resin (melt index 38 g / 10 min, weight average molecular weight 52000, sodium ion content 18 ppm), 24 parts basalt fiber (diameter 12 μm, length 4 mm, treated with γ-(2,3-epoxypropoxy)propyltrimethoxysilane, coating amount 1.1%), 18 parts composite insulating filler (molten silica to nano titanium dioxide mass ratio 3.5:1, micron D50=9 μm, nano D50=100 nm, organic titanate coupling agent coating thickness 7 nm), 3.5 parts maleic anhydride grafted polyphenylene sulfide (grafting rate 1.1%), 0.8 parts composite anti-aging agent (1010:168=1:1.5), and 0.25 parts nucleating agent phosphate salt.

[0082] The preparation process is as follows:

[0083] The first step is raw material pretreatment: polyphenylene sulfide resin is dried at 130℃ for 6 hours with a moisture content of 0.012%; surface-modified reinforcing fibers and composite insulating fillers are dried at 100℃ for 3 hours respectively.

[0084] The second step is premixing and modifying the filler: the dried composite insulating filler is put into a high-speed mixer and preheated to 80°C at 1900 rpm. An organic titanate coupling agent solution accounting for 1.4% of the filler mass is added and stirred continuously for 28 minutes.

[0085] The third step is melt blending extrusion: the twin-screw extruder has an L / D ratio of 46:1, the shearing zone length in the screw assembly accounts for 30% of the effective screw length, and the temperatures of the ten heating zones are set as follows: 272℃, 292℃, 308℃, 312℃, 312℃, 308℃, 302℃, 298℃, 292℃, and 288℃; the screw speed is 460 rpm, and the die pressure is 7.2 MPa; the vacuum degree is set at -0.092 MPa and -0.094 MPa in zones six and eight, respectively; the shear rate is controlled by adjusting the screw speed and feed rate. Maintain at Duration of stay The reaction time was 68 seconds. The value reached 0.96. The fourth step is granulation and post-processing: the extruded strips are cooled in a 75°C constant temperature water bath, air-dried and granulated, and then subjected to stress-relief annealing at 140°C for 2 hours.

[0086] Step 5, integrated molding: The annealed composite material particles are fed into the injection molding machine. The barrel temperature is 310℃, the injection pressure is 110MPa, the mold temperature is 145℃, the holding time is 22 seconds, and the cooling time is 45 seconds. The mold surface is coated with an 18μm polytetrafluoroethylene anti-stick layer. The infrared temperature monitoring and compensation system controls the temperature fluctuation of the mold cavity to ±1.2℃. The sequential valve hot runner technology is used to control the three gates to open sequentially with an opening time difference of 0.25 seconds.

[0087] Comparative Example 1: The components are basically the same as those in Example 1, except that: ordinary industrial-grade polyphenylene sulfide (sodium ion content 450ppm) is used, and maleic anhydride-grafted polyphenylene sulfide interface compatibilizer is not added, and the composite insulating filler is not modified by liquid-phase coating with organic titanate coupling agent.

[0088] Comparative Example 2: The components are basically the same as those in Example 1, except that the reinforcing fibers are not pretreated with silane coupling agents, and stress-relief annealing and mold infrared temperature control are not performed during the preparation process.

[0089] To further verify the effect of annealing on heat distortion temperature, Comparative Example 3 was prepared by omitting the stress-relief annealing step based on the formulation and process of Example 1. The heat distortion temperature of this sample was measured to be 252℃, while it was 272℃ after annealing, an increase of 20℃. This indicates that the annealing process has a significant contribution to the improvement of heat distortion temperature.

[0090] Table 1 below details the performance test data of the pole frame insulating composite materials prepared in the above embodiments and comparative examples.

[0091] Table 1: Summary of performance test data for each embodiment and comparative example;

[0092]

[0093] The measurement method for the local fluctuation gradient of the dielectric constant in Table 1 above is as follows:

[0094] A scanning probe microscopy (SPM) combined with dielectric microscopy was used to scan the dielectric constant in situ along a continuous region of at least 200 μm perpendicular to the electric field direction on the cross-section of the composite material. The dielectric constant was recorded at each measurement point, and the ratio of the difference in dielectric constant between adjacent measurement points to the distance was calculated. The average value of the ratio along the entire path was taken as the local fluctuation gradient, expressed in units of (1 / μm). In this test method, the sampling location was the central region of the electrode frame wall thickness, and the test environment temperature was 25℃±2℃. The degree of interfacial reaction was analyzed by infrared spectroscopy using the characteristic peak of the maleic anhydride group (1780 cm⁻¹). -1 ) and the characteristic peak of the benzene ring of polyphenylene sulfide (1575 cm⁻¹) -1 The change in the absorbance ratio of ( ) was determined.

[0095] Analysis of the data in Table 1 shows that, through strict component selection and process control, Examples 1-3 exhibit significantly better performance indicators than the comparative examples. Examples 2 and 3, in particular, achieved higher insulation resistivity at 150℃ due to the use of polyphenylene sulfide resin with lower sodium ion content, more precise micro / nano filler gradation, and stricter process control. and The DC breakdown field strengths reached 42.3 kV / mm and 40.8 kV / mm, respectively, both superior to Example 1. The interfacial reactivity degree reached over 0.95, corresponding to higher mechanical properties and interfacial stability.

[0096] Regarding insulation performance, the examples demonstrate power frequency dielectric strengths exceeding 30 kV / mm, and especially at high temperatures of 150°C, the insulation resistivity remains consistently high. In contrast, Comparative Example 1, due to its high sodium ion content and lack of interfacial modification, exhibited a significant degradation in insulation performance at high temperatures. The precise gradation of the micro / nano composite fillers and the engineered application of the Maxwell-Wagner effect in the examples resulted in extremely low local gradients in the dielectric constant, thereby significantly improving the breakdown field strength.

[0097] Furthermore, in chemical corrosion resistance tests, the strength retention rate of the embodiments of the present invention remained above 95% after immersion in strong acid and strong alkali environments for 3000 hours. This is attributed to the elimination of heterogeneous interfaces by the integrated molding process and the optimization of surface free energy (controlled between 35 mN / m and 45 mN / m). The low surface free energy not only endows the material with excellent hydrophobic and oleophobic properties but also prevents microscopic leakage of electrolyte along the material surface. Simultaneously, the addition of a nucleating agent in the embodiments resulted in a stable crystallization rate constant at 290°C. Stay to This resulted in a refined spherulitic structure, increasing the tortuosity of charge movement. This physically explains the mechanism by which the breakdown voltage is more than 40% higher than that of ordinary polyphenylene sulfide materials. Through precise control of the annealing process in the preparation process, the heat distortion temperature of all examples exceeded 260°C, ensuring that the pole frame could maintain a high-precision geometric profile even under extreme overload-induced temperature rise.

[0098] This invention provides a high-performance electrode frame insulation composite material that meets the stringent requirements of modern energy storage and conversion systems through molecular-level design, optimization of microstructure, and rigorous engineering processes. While achieving high insulation, high strength, and high stability, this material also significantly improves production efficiency and reduces manufacturing costs through an integrated injection molding process, giving it strong competitiveness in industrial applications.

[0099] Example 4: This example aims to verify the performance improvement of the composite material in terms of active electric field control after introducing piezoelectric ceramic functional modulator filler, as detailed below:

[0100] Components (by mass):

[0101] Polyphenylene sulfide resin: 50 parts (melt index 40 g / 10 min, weight average molecular weight 50,000, sodium ion content 28 ppm);

[0102] Surface-modified reinforcing fiber: 24 parts of alkali-free glass fiber (diameter 11μm, length 4.5mm, γ-aminopropyltriethoxysilane treated, coating amount 1.0%).

[0103] Composite insulating filler: 18 parts (molten silica to hexagonal boron nitride mass ratio 4:1, micron D50=8μm, nano D50=80nm, organotitanate coupling agent coating thickness 5nm).

[0104] Functionally controlled filler: 6 parts of barium titanate (BaTiO3) piezoelectric ceramic particles (average particle size D50=500nm, piezoelectric coefficient... The surface is coated with an organotitanate coupling agent with a coating thickness of 3 nm.

[0105] Interface compatibilizer: 3.5 parts of maleic anhydride-grafted polyphenylene sulfide (grafting rate 1.2%).

[0106] Compound anti-aging agent: 0.8 parts (1010:168=1:1.5);

[0107] Key adjustments to the preparation process: The following adjustments were made based on the process in Example 1:

[0108] Raw material pretreatment: Same as in Example 1.

[0109] Premixed modification of fillers: The composite insulating filler and the functional regulating filler are put into a high-speed mixer and preheated to 80°C at 1800 rpm. An organic titanate coupling agent solution accounting for 1.2% of the total mass of the fillers is added and stirred continuously for 25 minutes to ensure that a uniform insulating coating layer is formed on the surface of the functional regulating filler.

[0110] Melt blending extrusion: The screw speed was adjusted to 380 rpm (lower than 450 rpm in Example 1 to reduce shear heat and protect the crystal structure of the piezoelectric ceramic particles), and the die pressure was 6.0 MPa. The remaining temperature parameters were the same as in Example 1.

[0111] Integrated injection molding: mold temperature 145℃, holding pressure 100MPa, holding time 20 seconds. Key improvement: A miniature pressure sensor (located in the center area of ​​the frame) is installed inside the mold cavity to monitor the internal stress in real time during the holding and cooling stages. By adjusting the holding pressure curve, the internal residual stress of the pole frame after demolding is stabilized within the range of 8MPa to 12MPa, thereby achieving pre-polarization of the piezoelectric ceramic particles.

[0112] Performance testing and comparison:

[0113] Table 2: Comparison of performance test data between Example 1 and Example 4;

[0114]

[0115] In Example 4, the partial discharge initiation voltage jumped from 8.5 kV to 15.2 kV, an increase of 78.8%. This directly demonstrates the effect of internal stress on the piezoelectric ceramic particles. Built-in electric field generated under action It did indeed counteract the local external electric field spikes, upgrading from "passively capturing charges" to "actively suppressing charge injection".

[0116] The DC breakdown field strength of Example 4 (47.2 kV / mm) is significantly better than that of Example 1 (38.5 kV / mm). This is because the charge trap in the original scheme (provided by micro / nano fillers) and the newly added electric field shielding mechanism (provided by piezoelectric ceramics) form a double defense: the electric field shielding reduces the probability and energy of charge injection, allowing the subsequent charge trap to capture the injected charge more effectively.

[0117] By integrating a pressure sensor into the mold, it is possible to achieve... The closed-loop control ensures the stable operation of the piezoelectric effect, avoids performance inconsistencies caused by process fluctuations, and meets the requirements of industrial production.

[0118] To further verify the electric field shielding effect of the functionally modulated filler, electric field distribution simulation and experimental verification were performed on the sample of Example 4. A local model of the pole frame was established using finite element simulation software, and a 10kV DC voltage was applied. In the Example 1 model without piezoelectric ceramic particles, the maximum electric field distortion rate at the filler-matrix interface was 1.85 (i.e., the local field strength was 1.85 times the average field strength). However, in Example 4, due to the built-in electric field generated by the piezoelectric ceramic particles… The active compensation effect reduced the maximum electric field distortion rate to 1.32, a decrease of 28.6%. According to the formula calculate, , , (Relative permittivity of barium titanate), thus... .

[0119] An electrostatic probe was used to scan the electric field intensity along the surface of the electrode frame (200 mm in length) in 5 mm increments. In Example 1, the ratio of the maximum to minimum surface electric field intensity was 2.8:1, while in Example 4, this ratio was optimized to 1.8:1, indicating a 36% improvement in the uniformity of the surface electric field distribution. This improvement is directly reflected in a significant increase in the partial discharge initiation voltage, fundamentally solving the insulation failure problem caused by local electric field distortion in the electrode frame under complex operating conditions.

[0120] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0121] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. It should be noted that any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a pole frame insulating composite material, characterized in that, Includes the following steps: The first step is to dry the polyphenylene sulfide resin at 120°C to 140°C for 4 to 6 hours until the moisture content is less than 0.02%; the surface-modified reinforcing fibers and composite insulating fillers are dried at 100°C for 3 hours respectively. The second step involves putting the dried surface-modified reinforcing fiber and composite insulating filler into a high-speed mixer, preheating it to 80°C at a speed of 1500 rpm to 2000 rpm, adding an organic titanate coupling agent solution accounting for 1.0% to 1.5% of the filler mass, and stirring continuously for 20 to 30 minutes. The third step involves feeding the pretreated polyphenylene sulfide resin, interface compatibilizer, composite anti-aging agent, and modified composite insulating filler into a twin-screw extruder through the main feed port, and feeding the surface-modified reinforcing fiber through the side feed port, followed by melt blending extrusion. The twin-screw extruder has a length-to-diameter ratio (L / D) of 40:1 to 48:1, and the extrusion process is divided into ten heating zones. The temperatures of the first to tenth zones are set as follows: 265℃-275℃, 285℃-295℃, 300℃-310℃, 305℃-315℃, 305℃-315℃, 300℃-310℃, 295℃-305℃, 290℃-300℃, 285℃-295℃, and 280℃-290℃, respectively. The screw speed is set to 350 rpm to 500 rpm, and the die head pressure is controlled at 5 MPa to 8 MPa. The fourth step involves cooling the extruded strip in a constant temperature water bath at 60°C to 80°C, followed by air drying and pelletizing to obtain composite material particles; the composite material particles are then subjected to stress-relief annealing at 140°C for 2 hours. The fifth step involves feeding the annealed composite material particles into an injection molding machine. The frame is integrally injection molded at a barrel temperature of 290°C to 320°C, an injection pressure of 80MPa to 120MPa, and a mold temperature of 130°C to 150°C. The holding time is set to 15 to 25 seconds, and the cooling time is set to 30 to 50 seconds. The polyphenylene sulfide resin has a linear polymer structure, a weight-average molecular weight of 45,000 to 55,000, a melt viscosity of 150 Pa·s to 200 Pa·s at 315°C, a melt index of 30 g / 10 min to 50 g / 10 min, and a sodium ion mass fraction of less than 50 ppm.

2. The method for preparing a pole frame insulating composite material according to claim 1, characterized in that, The surface-modified reinforcing fiber is an alkali-free glass fiber or basalt fiber that has been surface-treated with a silane coupling agent, with a length of 3 mm to 6 mm and a single filament diameter of 10 μm to 13 μm; the silane coupling agent is γ-aminopropyltriethoxysilane or γ-(2,3-epoxypropoxy)propyltrimethoxysilane, with a coating amount of 0.8% to 1.2% of the fiber mass.

3. The method for preparing a pole frame insulating composite material according to claim 1, characterized in that, The composite insulating filler is composed of micron-sized insulating particles and nano-sized insulating particles in a mass ratio of 3:1 to 5:1; the micron-sized insulating particles are selected from one or more of calcined kaolin, molten silica, or aluminum nitride particles, with an average particle size D50 of 5μm to 12μm; the nano-sized insulating particles are hexagonal boron nitride or nano-titanium dioxide, with an average particle size D50 of 50nm to 150nm; the composite insulating filler is modified by liquid phase coating and its surface is coated with an organic titanate coupling agent film layer, the thickness of which is 3nm to 8nm.

4. The method for preparing a pole frame insulating composite material according to claim 1, characterized in that, The interface compatibilizer is maleic anhydride-grafted polyphenylene sulfide with a grafting rate of 0.8% to 1.5%; the composite anti-aging agent is composed of hindered phenolic antioxidant 1010 and phosphite antioxidant 168 in a mass ratio of 1:1 to 1:

2.

5. The method for preparing a pole frame insulating composite material according to claim 3, characterized in that, The particle size distributions of the micron-sized insulating particles and the nano-sized insulating particles satisfy the following spatial geometry filling model: in, The maximum volume fraction of the nanoscale insulating particles is dimensionless. The volume fraction of the micron-sized insulating particles is dimensionless. The average radius of the nanoscale insulating particles is given in units of 1. ; The average radius of the micron-sized insulating particles is given in units of . ;and ; This is the space ratio coefficient for a single sphere in the closest packing of spheres of equal diameter. This refers to the porosity when spheres of equal diameter are packed most densely, and it is dimensionless. The spatial geometric filling model is used to determine the ratio range of micron-sized insulating particles to nano-sized insulating particles, and the actual ratio is adjusted within ±20% of the value calculated by the model.

6. The method for preparing a pole frame insulating composite material according to claim 1, characterized in that, The polyphenylene sulfide resin has a sodium ion mass fraction of less than 50 ppm and a weight-average molecular weight of 45,000 to 55,000. By combining the low-sodium-ion content polyphenylene sulfide resin with micron-sized and nano-sized insulating particles graded in a mass ratio of 3:1 to 5:1, multi-scale charge traps are formed at the matrix-filler interface, increasing the trap density enhancement factor. satisfy: in, The trap density enhancement factor is dimensionless. The trap density in the composite material, in units of ; The trap density of the pure polyphenylene sulfide matrix is ​​expressed in units of... ; This is an empirical constant related to the surface activity of the packing material. It is dimensionless and ranges from 0.8 to 1.

2. Its specific value is determined by the BET specific surface area of ​​the packing material. The decision satisfies the empirical relation. ,in The BET specific surface area of ​​the composite insulating filler is given in units of... ; The volume fraction of micron-sized insulating particles, dimensionless; The volume fraction of nanoscale insulating particles, dimensionless; The volume fraction of the polyphenylene sulfide matrix is ​​dimensionless and satisfies the following conditions: ; is the average dielectric constant of the composite insulating filler, which is dimensionless; The dielectric constant of the polyphenylene sulfide matrix is ​​dimensionless; by... By controlling the value between 3.5 and 5.2, the charge migration rate is reduced to less than 20% of that of pure polyphenylene sulfide matrix.

7. The method for preparing a pole frame insulating composite material according to claim 4, characterized in that, During the melt blending process in the third step, the degree of interfacial reaction between the polyphenylene sulfide matrix and the interfacial compatibilizer... Over time The change satisfies the following second-order reaction model: in, The degree of interfacial reaction is dimensionless; Reaction time, in units of ; The reaction rate constant is expressed in units of 1000 m / s. ; With temperature The relationship conforms to the Arrhenius equation ,in Pre-exponential factors, in units of ; Activation energy, unit: ; Let be the ideal gas constant, and take the value of . ; Absolute temperature, unit: The maleic anhydride-grafted polyphenylene sulfide-matrix system described above was analyzed by differential scanning calorimetry (DSC). for to , orders of magnitude By controlling the temperature of the shearing section to be maintained between 305℃ and 315℃, Value at to Between, degree of reaction The extrusion residence time reaches 0.92 or higher.

8. The method for preparing a pole frame insulating composite material according to claim 1, characterized in that, During the injection molding process in the fifth step, the crystallization kinetics of polyphenylene sulfide are described by the following Avrami equation: in, Let be the relative crystallinity at time t, which is dimensionless; Crystallization time, in units of ; This is the crystallization rate constant, in units of... ; The Avrami index is dimensionless; the mold temperature is controlled between 130℃ and 150℃ to achieve this. Maintain at to ,and The value is between 2.5 and 3.0, which makes the crystallinity difference between different parts of the polar frame less than 3%.

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