Composite sheath of water vapor penetration resistant insulator and method for preparing insulator

Abstract

The present invention discloses a composite sheath of an insulator resistant to water vapor penetration, the sheath comprising an inner cylindrical waterproof layer and an outer cylindrical insulating layer, the inner circle of the outer cylindrical insulating layer is bonded to the outer circle of the inner cylindrical waterproof layer, the inner circle of the inner cylindrical waterproof layer is used to bond to a core rod, the inner cylindrical waterproof layer is used to prevent water and water vapor that penetrate through the outer cylindrical insulating layer from further penetrating into the core rod; the inner cylindrical waterproof layer is a vulcanized butyl rubber layer, and the outer cylindrical insulating layer is a vulcanized silicone rubber layer. The present invention also provides a method for preparing an insulator resistant to water vapor penetration. The combined sheath of butyl rubber and silicone rubber provides double protection for the insulator, preventing water and water vapor from penetrating into the core rod interface in a high temperature and high humidity environment, causing the epoxy core rod to decay and age.

Description

Technical Field

[0001] The invention relates to the technical field of electric power equipment, and in particular to a composite sheath of an insulator resistant to water vapor penetration and a method for preparing the insulator. Background Art

[0002] In recent years, with the popularization of infrared temperature measurement technology in power transmission line inspection, a large number of composite insulators operating in high-humidity areas in southern my country have been detected to have abnormal heating. Studies have shown that abnormal heating is closely related to the degradation of composite insulator materials. In high-temperature and high-humidity environments, during the long-term operation of composite insulators, the silicone rubber material absorbs moisture, and the moisture passes through the insulator sheath material into the core rod interface area, causing local discharge, abnormal heating, and core rod cracking and aging. The brittle deterioration of the core rod may further develop into brittle fracture, which will lead to string drop accidents, seriously threatening the safe operation of the power grid. Summary of the invention

[0003] The purpose of the present invention is to provide a composite sheath of an insulator resistant to water vapor penetration, in view of the defects of the prior art, wherein the sheath comprises an inner cylindrical waterproof layer and an outer cylindrical insulating layer, wherein the inner circle of the outer cylindrical insulating layer is bonded to the outer circle of the inner cylindrical waterproof layer, the inner circle of the inner cylindrical waterproof layer is used to bond to a core rod, and the inner cylindrical waterproof layer is used to prevent water and water vapor that penetrate through the outer cylindrical insulating layer from further penetrating into the core rod;

[0004] The inner cylindrical waterproof layer is a vulcanized butyl rubber layer, and the outer cylindrical insulating layer is a vulcanized silicone rubber layer.

[0005] Furthermore, the molecular weight of the vulcanized butyl rubber is 100,000-200,000.

[0006] Furthermore, the adhesive used to bond the inner circle of the inner cylindrical waterproof layer to the core rod is a first rubber hot-vulcanized adhesive, and the adhesive used to bond the inner circle of the outer cylindrical insulating layer to the outer circle of the inner cylindrical waterproof layer is a mixture of the first rubber hot-vulcanized adhesive and the second rubber hot-vulcanized adhesive. Further, the first rubber hot-vulcanized adhesive is Chemlock 6253 adhesive, and the second rubber hot-vulcanized adhesive is Chemlock 608 adhesive.

[0007] Furthermore, the material of the vulcanized silicone rubber layer is methyl vinyl silicone rubber.

[0008] A method for preparing a water vapor penetration resistant insulator comprises the following steps:

[0009] After coating the surface of the mandrel with a first rubber hot-vulcanizing adhesive, the surface of the mandrel is then coated with butyl rubber, and the butyl rubber is vulcanized to obtain a vulcanized butyl rubber layer on the surface of the mandrel;

[0010] After the second rubber hot-vulcanizing adhesive is wrapped on the surface of the vulcanized butyl rubber layer, the silicone rubber is wrapped on the surface of the butyl rubber by the second rubber hot-vulcanizing adhesive, and the silicone rubber is vulcanized to obtain a vulcanized silicone rubber layer on the surface of the butyl rubber layer;

[0011] The extrusion-wrapping umbrella-threading process is adopted to cover and fix a plurality of silicone rubber umbrella discs on the surface of the vulcanized silicone rubber layer.

[0012] Furthermore, before the surface of the mandrel is coated with the first rubber hot-vulcanizing adhesive, the mandrel is polished.

[0013] Furthermore, when the butyl rubber is vulcanized, the core rod wrapped with the butyl rubber is placed in a mold for vulcanization, the vulcanization temperature is 150° C.-190° C., and the vulcanization time is 30-40 minutes.

[0014] Furthermore, when the silicone rubber is vulcanized, it is first vulcanized in a drying oven for 20-40 seconds at a temperature of 500-600° C., and then placed in a drying room for secondary vulcanization at a temperature of 140-150° C. for 4-8 hours.

[0015] Furthermore, the method further comprises the following steps:

[0016] During the extrusion and umbrella-threading process, room temperature vulcanized silicone rubber is applied to the inner hole of the silicone rubber umbrella disk.

[0017] The beneficial effects of the present invention are:

[0018] 1. The dense arrangement of a large number of side methyl groups in the molecular weight of butyl rubber has a strong steric hindrance effect, which limits the thermal motion of polymer molecules, thereby achieving low permeability and high air tightness, and effectively preventing the penetration of gas molecules. The combination of the inner layer of butyl rubber and the outer layer of silicone rubber provides double protection for the insulator, which can prevent internal moisture and chemical erosion, and resist erosion from the external harsh environment. The design extends the service life of the insulator, reduces the frequency of replacement and maintenance, and reduces costs. Insulators with this structure are suitable for various harsh environments, such as high temperature, high humidity, and other occasions, and have broad application prospects.

[0019] 2. Conventional butyl rubber has a large molecular weight and is mainly used in the airtight layer of automobile tires. Due to its high molecular weight and poor processability, it is difficult to wrap it on the core rod. The present invention uses low molecular weight butyl rubber, which has certain fluidity and formability and good processability. After wrapping on the surface of the core rod, it is molded and vulcanized to form a butyl rubber sheath, which can block water vapor from penetrating into the composite insulator core rod under high humidity and heat environment, avoid aging and degradation of the epoxy core rod under humidity and heat conditions, and thus prevent the composite insulator from decaying and string breaking accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic structural diagram of the water vapor penetration resistant insulator of the present invention.

[0021] Reference numerals: 1 - silicone rubber layer; 2 - butyl rubber layer; 3 - core rod. DETAILED DESCRIPTION

[0022] The present invention is further described below by way of examples and comparative examples. The drugs used in the following examples are all commercially available products unless otherwise specified, and the methods used are all conventional methods in the art unless otherwise specified.

[0023] Example 1

[0024] like Figure 1 As shown, a composite sheath of a water vapor penetration resistant insulator, the sheath comprises an inner cylindrical waterproof layer 2 and an outer cylindrical insulating layer 1, the inner circle of the outer cylindrical insulating layer 1 is bonded to the outer circle of the inner cylindrical waterproof layer 2, the inner circle of the inner cylindrical waterproof layer 2 is used to bond to a core rod 3, and the inner cylindrical waterproof layer 2 is used to prevent water and water vapor that penetrate through the outer cylindrical insulating layer 1 from further penetrating into the core rod 3;

[0025] The inner cylindrical waterproof layer 2 is a vulcanized butyl rubber layer, and the outer cylindrical insulating layer 1 is a vulcanized silicone rubber layer.

[0026] The core rod material of the silicone rubber composite insulator is mainly glass fiber resin (also known as glass fiber reinforced plastic or FRP). This material is composed of glass fiber and resin matrix (epoxy resin in this embodiment) and has the characteristics of high strength, high modulus and corrosion resistance. Specifically, the glass fiber resin core rod plays a key structural support role in the composite insulator and can withstand the mechanical load of equipment such as conductors. It is usually made by impregnating glass fiber in resin and then undergoing processes such as vacuum injection, continuous pultrusion and curing. This core rod not only has excellent mechanical properties, but also can maintain stable performance during long-term use and is not easily affected by oxidation or ultraviolet rays.

[0027] The dense arrangement of a large number of side methyl groups in the molecular weight of butyl rubber has a strong steric hindrance effect, which limits the thermal motion of the polymer molecules, thereby achieving low permeability and high air tightness, and effectively preventing the penetration of gas molecules. The combination of the inner layer of butyl rubber and the outer layer of silicone rubber provides double protection for the insulator, which can prevent internal moisture and chemical corrosion, and resist corrosion from the external harsh environment. The design extends the service life of the insulator, reduces the frequency of replacement and maintenance, and reduces costs. Insulators with this structure are suitable for various harsh environments, such as high temperature, high humidity, heavy pollution, etc., and have broad application prospects.

[0028] The molecular weight of the vulcanized butyl rubber is 100,000-200,000. When the molecular weight of the butyl rubber is less than 100,000, the fluidity is too large, and when the molecular weight of the butyl rubber is greater than 200,000, the fluidity is too small. Whether the fluidity is too large or too small, it will affect the processing of the butyl rubber and is not suitable for the processing and molding of the butyl rubber on the surface of the mandrel.

[0029] The adhesive used to bond the inner circle of the inner cylindrical waterproof layer to the core rod is the first rubber hot vulcanized adhesive, and the adhesive used to bond the inner circle of the outer cylindrical insulating layer to the outer circle of the inner cylindrical waterproof layer is a mixture of the first rubber hot vulcanized adhesive and the second rubber hot vulcanized adhesive. Specifically, the first rubber hot vulcanized adhesive is Chemlok 6253 adhesive, and the second rubber hot vulcanized adhesive is Chemlok 608 adhesive. Chemlok 6253 adhesive is suitable for bonding butyl rubber, while Chemlok 608 adhesive is suitable for bonding silicone rubber.

[0030] The vulcanized butyl rubber has excellent air tightness and weather resistance. For silicone rubber, the unvulcanized silicone rubber molecular chain is linear or branched. Through vulcanization, the vulcanizer promotes the formation of a stable three-dimensional network structure between silicone rubber molecules, that is, a cross-linking reaction, so that the originally flexible molecular chains are "interwoven" together, so that the silicone rubber has good heat resistance, cold resistance, and aging resistance. The silicone rubber of this embodiment is subjected to secondary vulcanization. During the initial hot drying tunnel vulcanization process, the silicone rubber on the outer layer of the core rod is vulcanized, but the silicone rubber on the inside has not yet been vulcanized. The secondary vulcanization in the drying room can fully vulcanize the silicone rubber on the inside, and at the same time, the residual vulcanizer from the first vulcanization is fully decomposed.

[0031] Butyl rubber itself has good air tightness, which can effectively protect the inside of the insulator core rod from moisture erosion, and has good corrosion resistance to most chemicals. Silicone rubber has excellent electrical insulation, which helps to ensure the electrical safety of the insulator. Silicone rubber has high heat resistance and excellent cold resistance, can maintain stable performance under extreme temperature conditions, and is not easy to deform or crack. Silicone rubber has excellent resistance to ozone aging, heat aging, ultraviolet aging and atmospheric aging, and can maintain good physical and mechanical properties for a long time. The hydrophobicity of silicone rubber makes it resistant to pollution flashover, and it can operate safely in a heavy dirty environment, reducing maintenance workload. Silicone rubber has good anti-brittleness and creep resistance, is not easy to break, and can withstand certain impacts and vibrations to ensure the stable operation of the insulator. Relatively speaking, silicone rubber is more resistant to aging than butyl rubber, while butyl rubber is more moisture-resistant, so silicone rubber is used as the outer layer and butyl rubber as the inner layer.

[0032] The material of the vulcanized silicone rubber layer is methyl vinyl silicone rubber. Compared with other types of silicone rubber, methyl vinyl silicone rubber has more obvious advantages in electrical performance, especially in high voltage and harsh environment, its electrical performance is more stable and reliable, and its weather resistance is better, and its mechanical properties and processing performance are better.

[0033] Example 2

[0034] A method for preparing a water vapor penetration resistant insulator comprises the following steps:

[0035] After the first rubber hot-vulcanized adhesive is coated on the surface of the mandrel 3, butyl rubber is extruded by a rubber extruder and coated on the surface of the mandrel 3, and the butyl rubber is vulcanized to obtain a butyl rubber layer on the surface of the mandrel;

[0036] After the second rubber hot-vulcanized adhesive is coated on the surface of the butyl rubber layer, silicone rubber is extruded by a rubber extruder and coated on the surface of the butyl rubber, and the silicone rubber is vulcanized to obtain a silicone rubber layer on the surface of the butyl rubber layer;

[0037] Adopting the extrusion packing and umbrella-wearing process, a number of silicone rubber umbrella discs are put on the surface of the silicone rubber layer (the extrusion packing and umbrella-wearing process refers to putting the vulcanized silicone rubber umbrella discs on the epoxy core rod with a sheath according to a certain combination mode and umbrella spacing);

[0038] Electrical fittings are installed at both ends of the core rod covered with silicone rubber umbrella discs.

[0039] Before wrapping the first rubber hot vulcanization adhesive on the surface of the mandrel, the mandrel is polished. The first rubber hot vulcanization adhesive is Chemlock 6253 adhesive, and the second rubber hot vulcanization adhesive is Chemlock 608 adhesive. Preferably, it can be polished with 60 mesh corundum gauze paper. After polishing, the dust on the surface of the mandrel is wiped with anhydrous ethanol, 100mL of Chemlock 6253 adhesive is taken with a measuring cup, 300mL of anhydrous ethanol is added, and after stirring evenly, a clean rag is dipped in the adhesive, and the adhesive is applied to the surface of the epoxy mandrel with a rag, and then the epoxy mandrel is placed on a clean shelf for 30 minutes, and the butyl rubber is extruded and wrapped on the mandrel 3 through a package extruder.

[0040] When the butyl rubber is vulcanized, the mandrel 3 wrapped with butyl rubber is placed in a mold for vulcanization, the vulcanization temperature is 150℃-190℃, and the vulcanization time is 30-40 minutes. Preferably, the butyl rubber is coated on the surface of the mandrel and placed in a mold (the mold is used to prevent the butyl rubber from flowing and tightly coated on the surface of the mandrel) for vulcanization, the mold temperature is 175℃, and the molding is 35min. After vulcanization, it is taken out of the mold and cooled to room temperature for standby use. Within the temperature range of 150℃-190℃, the butyl rubber can be fully cross-linked to form a stable network structure. The vulcanized butyl rubber has better elasticity, strength and corrosion resistance, which can meet various application requirements. The selection of vulcanization time and temperature ensures quality while ensuring production efficiency, avoiding the cost increase caused by too long vulcanization cycle. If the vulcanization temperature is lower than 150℃, butyl rubber cannot be vulcanized. If the vulcanization temperature is higher than 190℃, the resin (such as epoxy resin) in the mandrel will decompose, causing irreversible damage to the performance of the mandrel. Moreover, if the vulcanization time exceeds 40 minutes, the butyl rubber will age, and if the vulcanization time is less than 30 minutes, the vulcanization will be incomplete.

[0041] When the silicone rubber is vulcanized, it is first vulcanized in a drying oven at a temperature of 500-600°C. The time in the drying oven is very short, generally 30 seconds. At this time, the surface of the core rod is already coated with a layer of butyl rubber. Therefore, the temperature of the core rod itself is not high, which will not cause the decomposition of the epoxy resin in the core rod. Since the time is very short, the butyl rubber and the adhesive will not be damaged. Then, it is placed in a drying room for secondary vulcanization at a temperature of 140-150°C and a vulcanization time of 4-8 hours. Preferably, 50 mL of Chemlock 6253 and 50 mL of Chemlock 608 adhesive are taken with a measuring cup, 300 mL of anhydrous ethanol is added and mixed evenly, the adhesive is dipped with a clean rag, the surface of the butyl rubber is wiped with the rag, and placed on a clean shelf for 30 minutes to allow the anhydrous ethanol to fully evaporate, and a layer of silicone rubber is extruded and coated on the surface of the butyl rubber with an extruder, and the surface of the silicone rubber is vulcanized by passing through a drying oven, and the drying oven temperature is controlled at 500-600°C according to the extrusion speed, and the surface of the silicone rubber is vulcanized, and the surface vulcanized mandrel is placed in a drying room for secondary vulcanization, and the secondary vulcanization temperature is controlled at 140-150°C, and the vulcanization time is 4 hours. The main function of the first drying oven vulcanization is to vulcanize the surface silicone rubber, and the first drying oven temperature is set at 500-600°C because within this temperature range, the cross-linking reaction of the silicone rubber can be carried out quickly and effectively, and since the time is only 30s, defects such as cracks or burning will not occur. Next is the second vulcanization in the drying room, which is mainly used to vulcanize the inner layer of silicone rubber and volatilize the residual vulcanizing agent decomposition products of the first vulcanization. Compared with the first vulcanization, the second vulcanization temperature is lower (140-150℃), but the time is longer (4-8 hours). The vulcanization process at this stage is slower and gentler, which helps to form a more uniform and stable cross-linked structure. The second vulcanization temperature should be set at 140-150℃ because within this temperature range, the cross-linking reaction of silicone rubber can continue, and at the same time, excessive temperature should be avoided to cause defects such as cracks or burning on the surface of silicone rubber. For Chemlock 608, the second vulcanization should not exceed 200℃, otherwise it will reduce the bonding performance. In addition, the lower temperature and longer time in the second vulcanization also help to eliminate the stress and residual stress inside the silicone rubber and improve the overall performance.

[0042] Furthermore, the method further comprises the following steps: applying room temperature vulcanized silicone rubber to the inner hole of the silicone rubber umbrella disc. Preferably, the silicone rubber umbrella disc is sheathed on the surface of the core rod in a large and small umbrella arrangement by using an extruded umbrella method (although the umbrella discs are made of ceramic and glass, since the surface of the insulator is silicone rubber, only the silicone rubber umbrella disc can be fixed), and room temperature vulcanized silicone rubber (RTV) is applied. After the RTV is cured, the umbrella disc is firmly adhered to the silicone rubber sheath, and power fittings are installed at both ends of the core rod, thus preparing a water vapor penetration resistant double-layer sheath composite insulator.

[0043] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A composite sheath for an insulator resistant to water vapor penetration, characterized in that: The sheath comprises an inner cylindrical waterproof layer and an outer cylindrical insulating layer, the inner circle of the outer cylindrical insulating layer is bonded to the outer circle of the inner cylindrical waterproof layer, the inner circle of the inner cylindrical waterproof layer is used to bond to the core rod, and the inner cylindrical waterproof layer is used to prevent water and water vapor that penetrate through the outer cylindrical insulating layer from further penetrating into the core rod; The inner cylindrical waterproof layer is a vulcanized butyl rubber layer, and the outer cylindrical insulating layer is a vulcanized silicone rubber layer.

2. The composite sheath of the water vapor penetration resistant insulator according to claim 1, characterized in that: The molecular weight of the butyl rubber in the vulcanized butyl rubber layer is 100,000-200,000.

3. The composite sheath of the water vapor penetration resistant insulator according to claim 1, characterized in that: The adhesive used to bond the inner circle of the inner cylindrical waterproof layer to the core rod is a first rubber hot vulcanized adhesive, and the adhesive used to bond the inner circle of the outer cylindrical insulating layer to the outer circle of the inner cylindrical waterproof layer is a mixture of the first rubber hot vulcanized adhesive and the second rubber hot vulcanized adhesive.

4. The composite sheath of the water vapor penetration resistant insulator according to claim 3, characterized in that: The first rubber hot-vulcanizing adhesive is Chemlok 6253 adhesive, and the second rubber hot-vulcanizing adhesive is Chemlok 608 adhesive.

5. The composite sheath of the water vapor penetration resistant insulator according to claim 1, characterized in that: The material of the vulcanized silicone rubber layer is methyl vinyl silicone rubber.

6. A method for preparing a water vapor penetration resistant insulator, characterized in that: The following steps are involved: After coating the surface of the mandrel with a first rubber hot-vulcanizing adhesive, the surface of the mandrel is then coated with butyl rubber, and the butyl rubber is vulcanized to obtain a vulcanized butyl rubber layer on the surface of the mandrel; After the second rubber hot-vulcanizing adhesive is wrapped on the surface of the vulcanized butyl rubber layer, the silicone rubber is wrapped on the surface of the butyl rubber by the second rubber hot-vulcanizing adhesive, and the silicone rubber is vulcanized to obtain a vulcanized silicone rubber layer on the surface of the butyl rubber layer; The extrusion-wrapping umbrella-threading process is adopted to cover and fix a plurality of silicone rubber umbrella discs on the surface of the vulcanized silicone rubber layer.

7. The method for preparing a water vapor penetration resistant insulator according to claim 6, characterized in that: Before the surface of the mandrel is coated with the first rubber hot-vulcanizing adhesive, the mandrel is ground.

8. The method for preparing a water vapor penetration resistant insulator according to claim 6, characterized in that: When the butyl rubber is vulcanized, the core rod wrapped with the butyl rubber is placed in a mold for vulcanization, the vulcanization temperature is 150° C.-190° C., and the vulcanization time is 30-40 minutes.

9. The method for preparing a water vapor penetration resistant insulator according to claim 6, characterized in that: When the silicone rubber is vulcanized, it is first vulcanized in a drying oven for 20-40 seconds at a temperature of 500-600° C., and then placed in a drying room for secondary vulcanization at a temperature of 140-150° C. for 4-8 hours.

10. The method for preparing a water vapor penetration resistant insulator according to claim 6, characterized in that: The following steps are also included: During the extrusion and umbrella-threading process, room temperature vulcanized silicone rubber is applied to the inner hole of the silicone rubber umbrella disk.

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