Preparation method of insulator with composite fluorinated silicone rubber insulating layer

Abstract

The invention provides a preparation method of an insulator with a composite fluorinated silicone rubber insulating layer, and belongs to the technical field of methods for manufacturing insulators. The method comprises the following steps: applying axial tension to a core rod to keep the core rod straight, and spraying a silane coupling agent solution to form an interface layer after plasma activation treatment; under the action of axial tension and radial tension, a flexible fluorinated silicone rubber material is injected to the interface layer to form a flexible substrate layer; when the vulcanization degree of the flexible substrate layer reaches a preset threshold value, injecting a reinforced fluorosilicone rubber material to the surface of the flexible substrate layer under a tension fluctuation controlled condition to form a reinforced layer; when the vulcanization degree of the reinforcing layer reaches a preset threshold value, applying a protective fluorosilicone rubber material to the surface of the reinforcing layer to form a protective surface layer, and performing overall high-temperature curing in a state of maintaining axial and radial tension; and connecting the fittings to the two ends of the core rod to obtain the insulator. The preparation method is used for improving the pollution flashover resistance, the mechanical property and the insulating property of the insulator.

Description

Technical Field

[0001] The invention belongs to the technical field of methods for manufacturing insulators, and in particular relates to a method for preparing an insulator with a composite fluorosilicone rubber insulating layer. Background Art

[0002] High-voltage insulators are key components in high-voltage transmission lines, providing insulation and support. Their performance directly impacts the safe and stable operation of transmission lines. Traditional high-voltage insulators are often made of a single material, such as ceramic, EPDM rubber, or ordinary silicone rubber. These materials suffer from issues such as insufficient flexibility, poor impact resistance, surface wear, and poor pollution flashover resistance.

[0003] In addition, the existing molding process is not adaptable enough: when conventional extrusion or injection molding processes are used to produce composite structure insulators, it is difficult to ensure the interface bonding strength of different materials (such as flexible and hard rubber), and delamination and peeling are prone to occur, affecting the overall mechanical properties and insulation reliability of the insulator. It is especially unsuitable for the harsh working conditions of high-voltage lines (such as severe cold, heat, dust, etc.).

[0004] Fluorosilicone rubber offers excellent high and low temperature resistance, weather resistance, and electrical insulation properties. However, single-hardness products struggle to simultaneously meet the insulator's dual requirements for internal flexibility and surface hardness. Furthermore, existing molding processes often rely on atmospheric curing, which can easily create bubbles and cause stress concentration within the rubber, impacting the insulator's mechanical and insulation properties.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] In view of the deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a method for preparing an insulator with a composite fluorosilicone rubber insulation layer to improve the pollution flashover resistance, mechanical properties and insulation performance of the insulator.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing an insulator with a composite fluorosilicone rubber insulation layer, comprising the following steps: S1: Provide core rod, silane coupling agent solution, flexible fluorosilicone rubber compound, reinforced fluorosilicone rubber compound and protective fluorosilicone rubber compound; S2: applying axial tension to the core rod to keep it straight, spraying the silane coupling agent solution after plasma activation treatment to form an interface layer; S3: Under the action of axial tension and radial tension, the flexible fluorosilicone rubber compound is injected into the interface layer to form a flexible base layer; S4: When the vulcanization degree of the flexible base layer reaches a preset threshold, injecting the reinforced fluorosilicone rubber compound onto the surface of the flexible base layer under tension fluctuation controlled conditions to form a reinforced layer; S5: When the vulcanization degree of the reinforcement layer reaches a preset threshold, applying the protective fluorosilicone rubber compound to the surface of the reinforcement layer to form a protective surface layer, and performing overall high-temperature curing while maintaining axial and radial tension; S6: Connect hardware to both ends of the core rod to obtain an insulator.

[0008] Furthermore, the core rod is an epoxy glass fiber core rod; The axial tension in step S2 is 10-15 MPa; The power of the plasma activation treatment is 200-400W, and the time is 100-140s; The silane coupling agent solution is a KH-550 solution with a volume concentration of 0.7-0.9%, and the solvent is a mixture of ethanol and water in a volume ratio of 8:2. The spraying amount is 100-150 mL per square meter of the core rod surface.

[0009] In this step, a certain axial tension is applied to keep the core rod straight, which is crucial to preventing the core rod from bending under subsequent stress and improving the performance of the insulation layer; plasma activation treatment is used to increase the surface energy of the core rod and enhance the bonding strength between the core rod and the interface layer; silane coupling agent is sprayed to form an interface layer, using the silane coupling agent as a bridge, with one end chemically bonded to the epoxy glass fiber core rod and the other end chemically bonded to the flexible fluorosilicone rubber compound, further greatly enhancing the bonding strength and long-term stability of the interface between the core rod and the flexible base layer.

[0010] Furthermore, in step S3, the pressure of injecting the flexible fluorosilicone rubber compound is 12-14 MPa, the radial tension is 5-8 MPa, and the axial tension and the radial tension are maintained synchronously.

[0011] In this step, a certain high-pressure injection ensures that the flexible rubber material can fully fill the surface of the core rod, eliminate bubbles, and achieve a tight fit; a certain radial tension is applied to the core rod so that the flexible base layer can wrap the core rod more tightly after curing, reducing internal stress or micropores; in this way, the flexible base layer can provide good flexibility, stress buffering and initial bonding with the core rod.

[0012] Furthermore, in step S4, the preset threshold value of the vulcanization degree of the flexible base layer is above 50%, and the tension fluctuation is controlled to be ≤±0.5 MPa.

[0013] In this step, when the preset threshold value of the vulcanization degree of the flexible base layer is above 50%, the reinforcing layer is injected, which can achieve good interlayer chemical bonding and avoid the risk of interface separation caused by the two layers being completely independent. Injection too early will cause the two layers to mix, and injection too late will weaken the interlayer bonding force. At the same time, the tension is precisely controlled to ensure the shape of the flexible base layer being cured or the uniformity of the injection of the reinforcing layer, thereby affecting the interlayer bonding and the integrity and uniformity of the final insulating layer. In this way, the purpose of providing mechanical strength and rigidity of the reinforcing layer is achieved.

[0014] Furthermore, in step S5, the preset threshold value of the vulcanization degree of the reinforcement layer is above 70%, the temperature of the high-temperature curing is 175-185° C., and the curing time is ≥30 min.

[0015] In this step, when the reinforcement layer's degree of vulcanization exceeds a preset threshold of 70%, the protective layer is sprayed on. This ensures a good bond between the protective surface and the reinforcement layer without damaging the reinforcement layer's structure. This ensures the protective surface layer provides excellent environmental aging resistance and hydrophobicity. Under high-temperature curing conditions, all rubber components are fully vulcanized to the desired degree of vulcanization.

[0016] During the entire process of steps S3-S5, a certain axial tension and radial tension are maintained simultaneously to ensure the uniformity of curing of each layer and the overall performance of the insulator. At the same time, deformation, delamination, internal stress accumulation or interface failure caused by differences in thermal expansion coefficients or stress relaxation of each layer under high-temperature curing are prevented. This is the key to ensuring the dimensional stability of the insulator and the long-term reliability of the interface.

[0017] Furthermore, the flexible fluorosilicone rubber compound is made from the following raw materials: 100 parts by weight of copolymerized fluorosilicone rubber containing methylphenylsiloxane chain segments, 30-40 parts by weight of composite filler, 2.5-3.5 parts by weight of structure control agent and 0.5-1.5 parts by weight of heat-resistant agent.

[0018] The copolymerized fluorosilicone rubber containing methylphenylsiloxane chain segments is obtained by mixing 6-8 parts by weight of methylphenylcyclosiloxane and 100 parts by weight of fluorosilicone rubber monomer having a fluorine content of 35-38%, and copolymerizing them under the action of an alkali metal hydroxide; The composite filler is a mixture of fluorinated white carbon black and silicon carbide whiskers in a weight ratio of 30:5; The structure control agent is dimethyl silicone oil; The heat-resistant agent is selected from γ-Fe2O3, SnO2 or CeO2.

[0019] In the present invention, fluorinated silica is silica with a fluorinated surface. As a composite filler component of the flexible rubber material, fluorinated silica and silicon carbide whiskers are mixed in a weight ratio of 30:5, which can enhance the mechanical strength of the flexible base layer. At the same time, its hydrophobicity is utilized to improve the pollution flashover resistance and environmental tolerance of the insulator, forming a synergistic effect with the fluorosilicone rubber system to optimize the comprehensive performance of the insulation layer.

[0020] The preparation steps of the flexible fluorosilicone rubber compound include: providing a copolymerized fluorosilicone rubber containing methylphenylsiloxane chain segments, a composite filler, a structure control agent, and a heat-resistant agent; feeding the above raw materials into a twin-screw extruder mixing system, controlling the mixing temperature at 170±2°C, the rotation speed at 30-50r / min, and the Mooney viscosity at 45±3MU to obtain the flexible fluorosilicone rubber compound.

[0021] Furthermore, the reinforced fluorosilicone rubber compound is made of the following raw materials: 100 parts by weight of fluorosilicone rubber raw rubber, 15-25 parts by weight of carbon fiber reinforcement, 5-7 parts by weight of nano titanium dioxide, 3-5 parts by weight of ethylene propylene rubber, 1-3 parts by weight of vulcanizing agent, and 1-2 parts by weight of accelerator.

[0022] Wherein: the vulcanizing agent is benzoyl peroxide or di-tert-butyl peroxide; The accelerator is a silane coupling agent.

[0023] The preparation steps of the reinforced fluorosilicone rubber compound include: providing fluorosilicone rubber raw rubber, carbon fiber reinforcement, nano-titanium dioxide, ethylene propylene rubber, a vulcanizing agent and an accelerator; feeding the above raw materials into a twin-screw extruder mixing system, controlling the mixing temperature at 170±2°C, the rotation speed at 30-50r / min, and the Mooney viscosity at 45±3MU to obtain the reinforced fluorosilicone rubber compound.

[0024] Furthermore, the protective fluorosilicone rubber compound is made of the following raw materials in parts by weight: 100 parts by weight of fluorosilicone rubber raw rubber, 25-35 parts by weight of a reinforcing agent, 3-5 parts by weight of a cross-linking agent, and 0.5-1.5 parts by weight of an anti-aging agent.

[0025] Wherein: the reinforcing agent is fumed silica, The cross-linking agent is dicumyl peroxide, The anti-aging agent is benzotriazole or Tinuvin 770.

[0026] In the present invention, the protective fluorosilicone rubber compound adopts fumed silica as a reinforcing agent to enhance the mechanical strength and weather resistance of the material, and effectively resist the erosion of environmental factors such as ultraviolet rays, ozone, and moisture.

[0027] The preparation steps of the protective fluorosilicone rubber compound include: providing fluorosilicone rubber raw rubber, a reinforcing agent, a cross-linking agent and an anti-aging agent; putting the above raw materials into a twin-screw extruder mixing system, controlling the mixing temperature at 170±2°C, the rotation speed at 30~50r / min, and the Mooney viscosity at 45±3MU to obtain the protective fluorosilicone rubber compound.

[0028] Furthermore, the hardware is connected to both ends of the core rod through interference fit, ensuring that the interface shear strength reaches 48 MPa, and the tolerance of the interference fit is ±0.015 mm.

[0029] Furthermore, the metal fittings are made of stainless steel, with a head length of 39 mm and a tail length of 41 mm, and a conductivity of 1.2×10 7 S / m.

[0030] Furthermore, the preparation method also includes: performing surface fluorination treatment on the protective surface layer, and the process parameters of the surface fluorination treatment include: plasma fluorination for 25 to 35 seconds, so that the static contact angle of the surface reaches more than 128°, thereby enhancing the hydrophobic migration ability of the insulator surface and further improving the pollution flashover resistance performance.

[0031] Furthermore, the preparation method further includes: performing gradient corrugation processing on the insulator, with the corrugation density of the top being 160 corrugations / m, the middle being 120 corrugations / m, and the bottom being 80 corrugations / m.

[0032] Furthermore, the preparation method also includes: conducting mechanical property and thermal aging tests on the insulator, wherein the mechanical property is: tensile speed 5mm / min, average tensile strength ≥1100MPa; thermal aging performance: thermal aging at 150°C for 1h, no surface damage, mechanical strength retention rate ≥85%, and insulation performance reduction ≤10%.

[0033] The present invention also provides an insulator having a composite fluorosilicone rubber insulation layer obtained by the above-mentioned preparation method, comprising: a core rod, an interface layer arranged on the surface of the core rod, a flexible base layer arranged on the surface of the interface layer, a reinforcement layer arranged on the surface of the flexible base layer, a protective surface layer arranged on the surface of the reinforcement layer, and hardware connected to both ends of the core rod.

[0034] Compared with the prior art, the present invention has the following beneficial effects: Based on the above technical solution, the present invention provides a method for preparing an insulator with a composite fluorosilicone rubber insulation layer, the purpose of which is to simultaneously improve the pollution flashover resistance, insulation and mechanical properties of the insulator, and overcome the performance shortcomings of traditional silicone rubber insulators.

[0035] The present invention uses an epoxy glass fiber core rod as a matrix and sequentially constructs a multilayer composite system of an interface layer, a flexible base layer, a reinforcement layer, and a protective surface layer. Each layer has a clear function and a gradual stiffness change, which not only ensures high-strength bonding between the core rod and the fluorosilicone rubber compound, but also enables the insulating layer to have high hardness, high hydrophobicity, and excellent anti-aging ability.

[0036] The present invention first pre-treats the core rod by plasma-activating its surface, then spraying it with a silane coupling agent solution to form an interface layer. Layered lamination is then performed, using a combination of injection and spraying of three layers: an internal flexible fluorosilicone rubber compound, an intermediate reinforcing fluorosilicone rubber compound, and a surface protective fluorosilicone rubber compound, to achieve a smooth transition from soft to hard. During the curing process, 10-15 MPa of axial tension and 5-8 MPa of radial tension are applied throughout to ensure the core rod is straight, the layers fit tightly, and the dimensions are stable, reducing internal stress, eliminating bubbles, and preventing delamination. This completes the multi-layer integrated molding process, eliminating interface defects and improving density.

[0037] The performance indicators of the insulator obtained by the preparation method of the present invention are as follows: (1) Mechanical properties: tested by universal testing machine, tensile speed 5mm / min, average tensile strength ≥1100MPa.

[0038] (2) Thermal aging: 150℃×1h, no cracks or powdering on the surface; mechanical strength retention rate ≥85%, insulation performance decrease ≤10%.

[0039] (3) Hydrophobicity: According to GB / T24622-2009, the contact angles measured in three areas along the longitudinal direction and around the circumference of the insulator are all >80°, with excellent hydrophobic migration performance and significantly improved pollution flashover resistance.

[0040] It can be seen that the insulator preparation method of the present invention adopts a process combining multi-layer composite, layered curing, and surface modification to produce a composite insulator for power transmission and transformation with high reliability, long life, and resistance to harsh environments. It significantly improves the mechanical strength, insulation performance, and durability of the insulator, and can well adapt to temperature changes from -60°C to 200°C. It has excellent heat resistance and is suitable for mass production of composite insulators for the full voltage level of 10kV-1000kV. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0042] Figure 1: A schematic structural diagram of an insulator with a composite fluorosilicone rubber insulating layer according to the present invention; Figure 2 : The present invention Figure 1 AA cross-sectional diagram in; Figure 3 :The simulation model diagram of the insulator obtained based on COMSOL Multiphysics multi-field coupling analysis software; Among them, 1. core rod; 2. umbrella skirt; 3. hardware; 4. interface layer; 5. flexible base layer; 6. reinforcement layer; 7. protective surface layer. DETAILED DESCRIPTION

[0043] In order to better understand the present invention, the content of the present invention is further clearly set forth below in conjunction with the examples, but the protection content of the present invention is not limited to the following examples. In the following description, a large number of specific details are provided in order to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details.

[0044] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0045] Unless otherwise specified, all raw materials are derived from commercially available products and do not contain other unspecified components except inevitable impurities.

[0046] like Figure 1-3 As shown, an insulator with a composite fluorosilicone rubber insulation layer includes: a core rod 1, a shed 2, and a hardware fixture 3. The shed 2 is provided on the outer surface of the core rod 1, and the hardware fixture 3 is connected to both ends of the core rod 1. The shed 2 is formed by sequentially curing a flexible base layer 5, a reinforcement layer 6, and a protective surface layer 7. An interface layer 4 is provided between the surface of the core rod 1 and the flexible base layer 5. The inner surface of the reinforcement layer 6 is connected to the flexible base layer 5, and the outer surface is connected to the protective surface 7. The hardware fixture 3 is connected to both ends of the core rod 1 through an interference fit, ensuring an interface shear strength of 48 MPa, with an interference fit tolerance of ±0.015 mm.

[0047] In the following embodiments, the core rod 1 is an epoxy glass fiber core rod with a conductivity of 10 -14 S / m.

[0048] The fitting 3 is made of stainless steel, with a length of 39 mm at the head and 41 mm at the tail, and a conductivity of 1.2 × 10 7 S / m.

[0049] The shed 2 is processed with gradient corrugations, with a corrugation density of 160 / m at the top, 120 / m in the middle, and 80 / m at the bottom.

[0050] The following is a specific preparation example of an insulator.

[0051] Example 1: Preparation of flexible fluorosilicone rubber compound The flexible fluorosilicone rubber compound is prepared from the following raw materials: 100 parts by weight of copolymerized fluorosilicone rubber containing methylphenylsiloxane chain segments, 35 parts by weight of composite filler, 3 parts by weight of structure control agent and 1 part by weight of heat-resistant agent.

[0052] Among them: the copolymerized fluorosilicone rubber containing methylphenylsiloxane chain segments is obtained by mixing 7 weight parts of methylphenyl cyclosiloxane and 100 weight parts of fluorosilicone rubber raw rubber monomer with a fluorine content of 36%, and copolymerizing them under the action of potassium hydroxide, with a reaction temperature of 110°C and a reaction time of 2 hours; the composite filler is a mixture of fluorinated white carbon black and silicon carbide whiskers in a weight ratio of 30:5; the structure control agent is dimethyl silicone oil; and the heat-resistant agent is γ-Fe2O3.

[0053] The preparation steps of the flexible fluorosilicone rubber compound include: providing a copolymerized fluorosilicone rubber containing methylphenylsiloxane chain segments, a composite filler, a structure control agent and a heat-resistant agent; feeding the above raw materials into a twin-screw extruder mixing system, controlling the mixing temperature at 170±2°C, the rotation speed at 40r / min, and the Mooney viscosity at 45±3MU to obtain the flexible fluorosilicone rubber compound.

[0054] Example 2: Preparation of reinforced fluorosilicone rubber compound The reinforced fluorosilicone rubber compound is made of the following raw materials: 100 parts by weight of fluorosilicone rubber raw rubber, 20 parts by weight of carbon fiber reinforcement material, 6 parts by weight of nano titanium dioxide, 4 parts by weight of ethylene propylene rubber, 2 parts by weight of vulcanizing agent, and 1.5 parts by weight of accelerator.

[0055] Among them: the vulcanizing agent is benzoyl peroxide; the accelerator is a silane coupling agent.

[0056] The preparation steps of the reinforced fluorosilicone rubber compound include: providing fluorosilicone rubber raw rubber, carbon fiber reinforcement material, nano-titanium dioxide, ethylene propylene rubber, a vulcanizing agent and an accelerator; putting the above raw materials into a twin-screw extruder mixing system, controlling the mixing temperature at 170±2°C, the rotation speed at 40r / min, and the Mooney viscosity at 45±3MU to obtain the reinforced fluorosilicone rubber compound.

[0057] Example 3: Preparation of reinforced fluorosilicone rubber compound The protective fluorosilicone rubber compound is made of the following raw materials in parts by weight: 100 parts by weight of fluorosilicone rubber raw rubber, 30 parts by weight of a reinforcing agent, 4 parts by weight of a cross-linking agent and 1 part by weight of an anti-aging agent.

[0058] Among them: the reinforcing agent is fumed silica, the cross-linking agent is dicumyl peroxide, and the anti-aging agent is benzotriazole.

[0059] The preparation steps of the protective fluorosilicone rubber compound include: providing fluorosilicone rubber raw rubber, a reinforcing agent, a cross-linking agent and an anti-aging agent; putting the above raw materials into a twin-screw extruder mixing system, controlling the mixing temperature at 170±2°C, the rotation speed at 40r / min, and the Mooney viscosity at 45±3MU to obtain the protective fluorosilicone rubber compound.

[0060] The flexible fluorosilicone rubber compound, the reinforced fluorosilicone rubber compound and the protective fluorosilicone rubber compound used in the following examples and comparative examples were prepared with reference to Examples 1-3, respectively.

[0061] Example 4: A method for preparing an insulator having a composite fluorosilicone rubber insulation layer, characterized in that it comprises the following steps: S1: Provide core rod, silane coupling agent solution, flexible fluorosilicone rubber compound, reinforced fluorosilicone rubber compound and protective fluorosilicone rubber compound; S2: Apply axial tension to the core rod to keep it straight, and spray silane coupling agent solution to form an interface layer after plasma activation treatment; S3: Under the action of axial tension and radial tension, the flexible fluorosilicone rubber compound is injected into the interface layer to form a flexible base layer; S4: When the vulcanization degree of the flexible base layer reaches a preset threshold, the reinforced fluorosilicone rubber compound is injected onto the surface of the flexible base layer under tension fluctuation controlled conditions to form a reinforcement layer; S5: When the degree of vulcanization of the reinforcement layer reaches a preset threshold, the protective fluorosilicone rubber compound is sprayed onto the surface of the reinforcement layer to form a protective surface layer, and the entire layer is cured at high temperature while maintaining axial and radial tension; S6: Connect the hardware to both ends of the core rod to obtain the insulator.

[0062] In step S2, the axial tension is 12 MPa; the power of the plasma activation treatment is 300 W, and the time is 120 s; the silane coupling agent solution is a KH-550 solution with a volume concentration of 0.8%, and the solvent is a mixture of ethanol and water in a volume ratio of 8:2. The spraying amount is 120 mL per square meter of the core rod surface, and the bonding strength reaches 9.2 kN / m.

[0063] In step S3, the pressure of injecting the flexible fluorosilicone rubber compound is 13 MPa, the radial tension is 6 MPa, and the axial tension and the radial tension are maintained synchronously.

[0064] In step S4, the preset threshold value of the vulcanization degree of the flexible base layer is 50%, and the tension fluctuation is controlled within ±0.5 MPa.

[0065] In step S5, the preset threshold value of the vulcanization degree of the reinforcement layer is 70%, the high-temperature curing temperature is 180° C., and the curing time is 30 minutes.

[0066] The mechanical properties of the insulator in this embodiment are as follows: tested on a universal testing machine at a tensile speed of 5 mm / min, with an average tensile strength of 1123 MPa; thermal aging performance: thermal aging at 150°C for 1 hour revealed no surface damage, a mechanical strength retention rate of 91.5%, and a 5.2% decrease in insulation performance; and contact angles measured in three regions longitudinally and circumferentially of the insulator in accordance with GB / T 24622-2009 were all >81°.

[0067] Example 5: A method for preparing an insulator having a composite fluorosilicone rubber insulating layer, which differs from Example 1 in that: In step S2, the axial tension is 10 MPa; the power of the plasma activation treatment is 200 W, and the time is 140 s; the silane coupling agent solution is a KH-550 solution with a volume concentration of 0.7%, and the solvent is a mixture of ethanol and water in a volume ratio of 8:2. The spraying amount is 150 mL per square meter of the core rod surface, and the bonding strength reaches 9.3 kN / m.

[0068] In step S3, the pressure of injecting the flexible fluorosilicone rubber compound is 12 MPa, the radial tension is 5 MPa, and the axial tension and the radial tension are maintained synchronously.

[0069] In step S4, the preset threshold value of the vulcanization degree of the flexible base layer is above 50%, and the tension fluctuation is controlled within ±0.5 MPa.

[0070] In step S5, the preset threshold value of the vulcanization degree of the reinforcement layer is 70%, the high-temperature curing temperature is 175° C., and the curing time is 32 minutes.

[0071] The mechanical properties of the insulator in this embodiment are as follows: tested on a universal testing machine at a tensile speed of 5 mm / min, with an average tensile strength of 1105 MPa; thermal aging performance: thermal aging at 150°C for 1 hour, with no surface damage, a mechanical strength retention rate of 88.7%, and a reduction in insulation performance of 5.8%; and contact angles measured in three areas longitudinally and around the circumference of the insulator in accordance with GB / T24622-2009 are all greater than 80°.

[0072] Example 6: A method for preparing an insulator having a composite fluorosilicone rubber insulating layer, which differs from Example 1 in that: In step S2, the axial tension is 15 MPa; the power of the plasma activation treatment is 400 W, and the time is 100 s; the silane coupling agent solution is a KH-550 solution with a volume concentration of 0.9%, and the solvent is a mixture of ethanol and water in a volume ratio of 8:2. The spraying amount is 100 mL per square meter of the core rod surface, and the bonding strength reaches 9.3 kN / m.

[0073] In step S3, the pressure of injecting the flexible fluorosilicone rubber compound is 14 MPa, the radial tension is 8 MPa, and the axial tension and the radial tension are maintained synchronously.

[0074] In step S4, the preset threshold value of the vulcanization degree of the flexible base layer is 50%, and the tension fluctuation is controlled within ±0.5 MPa.

[0075] In step S5, the preset threshold value of the vulcanization degree of the reinforcement layer is 70%, the high-temperature curing temperature is 185° C., and the curing time is 30 minutes.

[0076] The mechanical properties of the insulator in this embodiment are as follows: tested on a universal testing machine at a tensile speed of 5 mm / min, with an average tensile strength of 1114 MPa; thermal aging performance: thermal aging at 150°C for 1 hour, with no surface damage, a mechanical strength retention rate of 90.3%, and a 6.5% decrease in insulation performance; and contact angles measured in three areas longitudinally and around the circumference of the insulator in accordance with GB / T24622-2009 are all greater than 80°.

[0077] Example 7: A method for preparing an insulator with a composite fluorosilicone rubber insulation layer is based on Example 1 and adds the following steps: surface fluorination treatment of the protective surface layer, the process parameters of the surface fluorination treatment include: plasma fluorination for 30s, a static contact angle of 128° on the surface, enhancing the hydrophobic migration ability of the insulator surface, and further improving the pollution flashover resistance performance.

[0078] The mechanical properties of the insulator in this embodiment are as follows: tested on a universal testing machine at a tensile speed of 5 mm / min, with an average tensile strength of 1140 MPa; thermal aging performance: thermal aging at 150°C for 1 hour, with no surface damage, a mechanical strength retention rate of 92.7%, and a 4.5% decrease in insulation performance; and contact angles measured in three areas longitudinally and around the circumference of the insulator in accordance with GB / T24622-2009 are all greater than 85°.

[0079] The following are comparative examples.

[0080] Comparative Example 1: A method for preparing an insulator having a composite fluorosilicone rubber insulation layer, which differs from Example 1 in that: step S2 of "spraying a silane coupling agent solution to form an interface layer" is omitted, and the relevant steps are adaptively adjusted as follows: S2': applying axial tension to the core rod to keep it straight and performing plasma activation treatment; S3': Under the action of axial tension and radial tension, the flexible fluorosilicone rubber compound is injected onto the surface of the core rod to form a flexible base layer; The remaining steps and parameters are the same as those in Example 1.

[0081] The mechanical properties of the insulator in this comparative example are as follows: tested on a universal testing machine at a tensile speed of 5 mm / min, with an average tensile strength of 912 MPa; thermal aging performance: after thermal aging at 150°C for 1 hour, the surface showed no damage, a mechanical strength retention rate of 83.4%, and a decrease in insulation performance of 6.7%; and the contact angles measured in three areas longitudinally and around the circumference of the insulator in accordance with GB / T24622-2009 were all >81°.

[0082] It can be seen that compared with Example 1, in Comparative Example 1, when the core rod is not sprayed with the silane coupling agent solution, the average tensile strength of the insulator decreases by 18.8%, the mechanical strength retention rate after heat aging decreases by 8.1%, and the overall mechanical properties and mechanical strength of the insulator after heat treatment are significantly reduced.

[0083] Comparative Example 2: A method for preparing an insulator having a composite fluorosilicone rubber insulation layer, which differs from Example 1 in that step S4 is omitted and the relevant steps are adaptively adjusted as follows: S5': When the vulcanization degree of the flexible base layer reaches 50%, the protective fluorosilicone rubber compound is applied to the surface of the flexible base layer and the entire layer is cured at high temperature while maintaining axial and radial tension; The remaining steps and parameters are the same as those in Example 1.

[0084] The mechanical properties of the insulator in this comparative example are as follows: tested on a universal testing machine at a tensile speed of 5 mm / min, with an average tensile strength of 873 MPa; thermal aging performance: after thermal aging at 150°C for 1 hour, the surface showed no damage, a mechanical strength retention rate of 78.1%, and a decrease in insulation performance of 12.6%; and the contact angles measured in three areas along the longitudinal direction and around the circumference of the insulator in accordance with GB / T24622-2009 were all greater than 81°.

[0085] It can be seen that compared with Example 1, in Comparative Example 2, when the reinforcement layer is omitted, the average tensile strength of the insulator decreases by 22.3%, the mechanical strength retention rate after thermal aging decreases by 13.4%, and the insulation performance decreases by 7.4%. The overall mechanical properties of the insulator and the mechanical strength and insulation performance under heat treatment are significantly reduced.

[0086] Comparative Example 3: A method for preparing an insulator having a composite fluorosilicone rubber insulation layer, which differs from Example 1 in that: in the processing of steps S3-S5, no radial tension is applied to the core rod; the remaining steps and parameters are the same as those in Example 1.

[0087] The mechanical properties of the insulator in this comparative example are as follows: tested on a universal testing machine at a tensile speed of 5 mm / min, with an average tensile strength of 904 MPa; thermal aging performance: after thermal aging at 150°C for 1 hour, the surface showed no damage, a mechanical strength retention rate of 84.5%, and a decrease in insulation performance of 9.3%; and the contact angles measured in three areas longitudinally and around the circumference of the insulator in accordance with GB / T24622-2009 were all greater than 81°.

[0088] It can be seen that compared with Example 1, in Comparative Example 3, when no radial tension is applied to the core rod, the average tensile strength of the insulator decreases by 19.5%, the mechanical strength retention rate after thermal aging decreases by 7.0%, and the insulation performance decreases by 4.1%. The overall mechanical properties of the insulator and the mechanical strength and insulation performance after heat treatment are significantly reduced.

[0089] In summary, steps S1-S6 in the insulator preparation method of the present invention interact with each other as a whole and are inseparable. The system solves key problems in the traditional composite insulator manufacturing, such as weak adhesion between the core rod and the rubber interface, easy separation between layers, poor uniformity of the insulating layer, and high internal stress. The insulator exhibits excellent pollution flashover resistance, mechanical properties, and insulation properties, which can meet the use requirements of high-voltage insulators in extreme environments.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and are not limiting. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in this field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for preparing an insulator having a composite fluorosilicone rubber insulation layer, characterized in that: The following steps are involved: S1: Provide core rod, silane coupling agent solution, flexible fluorosilicone rubber compound, reinforced fluorosilicone rubber compound and protective fluorosilicone rubber compound; S2: applying axial tension to the core rod to keep it straight, spraying the silane coupling agent solution after plasma activation treatment to form an interface layer; S3: Under the action of axial tension and radial tension, the flexible fluorosilicone rubber compound is injected into the interface layer to form a flexible base layer; S4: When the vulcanization degree of the flexible base layer reaches a preset threshold, injecting the reinforced fluorosilicone rubber compound onto the surface of the flexible base layer under tension fluctuation controlled conditions to form a reinforced layer; S5: When the vulcanization degree of the reinforcement layer reaches a preset threshold, applying the protective fluorosilicone rubber compound to the surface of the reinforcement layer to form a protective surface layer, and performing overall high-temperature curing while maintaining axial and radial tension; S6: Connect hardware to both ends of the core rod to obtain an insulator.

2. The method for preparing an insulator having a composite fluorosilicone rubber insulation layer according to claim 1, wherein: The axial tension in step S2 is 10-15 MPa; The power of the plasma activation treatment is 200-400W, and the time is 100-140s; The silane coupling agent solution is a KH-550 solution with a volume concentration of 0.7-0.9%, and the solvent is a mixture of ethanol and water in a volume ratio of 8:

2. The spraying amount is 100-150 mL per square meter of the core rod surface.

3. The method for preparing an insulator having a composite fluorosilicone rubber insulation layer according to claim 2, characterized in that: In step S3, the pressure of injecting the flexible fluorosilicone rubber compound is 12-14 MPa, the radial tension is 5-8 MPa, and the axial tension and the radial tension are maintained synchronously.

4. The method for preparing an insulator having a composite fluorosilicone rubber insulation layer according to claim 3, characterized in that: In step S4, the preset threshold value of the vulcanization degree of the flexible base layer is above 50%, and the tension fluctuation is controlled to be ≤±0.5MPa.

5. The method for preparing an insulator having a composite fluorosilicone rubber insulation layer according to claim 4, characterized in that: The preset threshold value of the vulcanization degree of the reinforcement layer in step S5 is above 70%, the temperature of the high-temperature curing is 175-185° C., and the curing time is ≥30 min.

6. The method for preparing an insulator having a composite fluorosilicone rubber insulation layer according to claim 5, characterized in that: The flexible fluorosilicone rubber compound is made of the following raw materials: 100 parts by weight of copolymerized fluorosilicone rubber containing methylphenylsiloxane chain segments, 30-40 parts by weight of composite filler, 2.5-3.5 parts by weight of structure control agent, and 0.5-1.5 parts by weight of heat-resistant agent; The preparation steps of the flexible fluorosilicone rubber compound include: providing a copolymerized fluorosilicone rubber containing methylphenylsiloxane chain segments, a composite filler, a structure control agent, and a heat-resistant agent; feeding the above raw materials into a twin-screw extruder mixing system, controlling the mixing temperature at 170±2°C, the rotation speed at 30-50r / min, and the Mooney viscosity at 45±3MU to obtain the flexible fluorosilicone rubber compound.

7. The method for preparing an insulator having a composite fluorosilicone rubber insulation layer according to claim 6, characterized in that: The reinforced fluorosilicone rubber compound is made of the following raw materials: 100 parts by weight of fluorosilicone rubber, 15-25 parts by weight of carbon fiber reinforcement, 5-7 parts by weight of nano-titanium dioxide, 3-5 parts by weight of ethylene-propylene rubber, 1-3 parts by weight of vulcanizing agent, and 1-2 parts by weight of accelerator; The preparation steps of the reinforced fluorosilicone rubber compound include: providing fluorosilicone rubber raw rubber, carbon fiber reinforcement, nano-titanium dioxide, ethylene propylene rubber, a vulcanizing agent and an accelerator; feeding the above raw materials into a twin-screw extruder mixing system, controlling the mixing temperature at 170±2°C, the rotation speed at 30-50r / min, and the Mooney viscosity at 45±3MU to obtain the reinforced fluorosilicone rubber compound.

8. The method for preparing an insulator having a composite fluorosilicone rubber insulation layer according to claim 7, wherein: The protective fluorosilicone rubber compound is made of the following raw materials in parts by weight: 100 parts by weight of fluorosilicone rubber, 25-35 parts by weight of a reinforcing agent, 3-5 parts by weight of a cross-linking agent, and 0.5-1.5 parts by weight of an anti-aging agent; The preparation steps of the protective fluorosilicone rubber compound include: providing fluorosilicone rubber raw rubber, a reinforcing agent, a cross-linking agent and an anti-aging agent; putting the above raw materials into a twin-screw extruder mixing system, controlling the mixing temperature at 170±2°C, the rotation speed at 30~50r / min, and the Mooney viscosity at 45±3MU to obtain the protective fluorosilicone rubber compound.

9. The method for preparing an insulator having a composite fluorosilicone rubber insulation layer according to claim 8, characterized in that: The hardware is connected to both ends of the core rod by interference fit, ensuring that the interface shear strength reaches 48 MPa, and the tolerance of the interference fit is ±0.015 mm; The metal fittings are made of stainless steel, with a head length of 39 mm and a tail length of 41 mm, and a conductivity of 1.2×10 7 S / m.

10. A method for preparing an insulator having a composite fluorosilicone rubber insulation layer according to any one of claims 1 to 9, characterized in that: Also includes: The protective surface layer is subjected to plasma fluorination for 25 to 35 seconds.

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