JPS6126206B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of manufacturing an electrical insulating device, and more particularly to a method of manufacturing an electrical insulating device suitable for use in electrical windings of rotating electrical equipment, stationary induction electrical equipment, and the like. In general, resins whose main components are polyfunctional epoxy compounds and polyfunctional isocyanate compounds, which are used as insulation for electric windings in rotating electric machines such as generators and electric motors, and stationary induction electric appliances such as transformers, are used in the presence of a curing catalyst. By heating at a lower temperature, it becomes a cured product with excellent heat resistance, and can be used for insulation of heat resistance classification H class or higher. However, the problem with this resin is that the polyfunctional isocyanate in its composition reacts with moisture and generates carbon dioxide gas, which causes voids due to foaming to occur in the insulating layer, resulting in a decrease in dielectric strength. There is. Therefore, in the previously proposed patent application No. 49-116092 (Japanese Patent Application Laid-Open No. 51-43000), the moisture content in the insulating layer is set below a certain value, and the primary curing temperature until gelation of the resin is set below 80°C. As a result, the reaction during curing is controlled to prevent the generation of carbon dioxide gas. However, in order to reduce the moisture content in the insulating layer to a certain level or less, it is necessary to perform heat drying or vacuum drying. Since it is exposed to the atmosphere, moisture is absorbed on the surface of the insulating layer and into the insulating layer at this point. If the resin is impregnated into the insulating layer in such a moisture-absorbing state, the polyfunctional isocyanate will react with moisture, and the problem of foaming due to the generated carbon dioxide gas cannot be avoided. In addition, if the injected resin flows out of the insulating layer, the insulation performance cannot be improved, so in order to further improve the insulation performance, it is necessary to prevent the injected resin from flowing out of the insulating layer. is important. The present invention has been made in view of the above points, and its purpose is to prevent the insulating layer from absorbing moisture even if it is exposed to the atmosphere after leaving the drying oven and entering the resin injection process. Therefore, it is an object of the present invention to provide a method for manufacturing an electrical insulating device that can prevent foaming due to the generation of carbon dioxide gas and improve insulation performance by preventing injected resin from flowing out of the insulating layer. In the present invention, an insulating material is wound around an electrical conductor to form an insulating layer, a release tape for preventing moisture absorption is wrapped around the outside of this insulating layer, and a tape for preventing resin leakage is placed on the release tape. It is rolled up and dried in a drying oven, then impregnated with a resin whose main components are a polyfunctional epoxy compound and a polyfunctional isocyanate compound and cured by heating, and then the release tape and the tape for preventing resin leakage are removed. By doing so, the intended purpose was achieved. That is, as mentioned above, the cause of foaming in the insulating layer is moisture, and although this moisture can be removed in the drying process, the product is exposed to the atmosphere when entering the next process, the resin injection process. Therefore, at this point, the inside of the insulating layer and the surface of the insulating layer absorb moisture. In order to prevent the formation of harmful bubbles in the insulating layer and on the insulating surface due to this moisture absorption, it is necessary to prevent the surface of the insulating layer from coming into direct contact with the atmosphere even during the resin injection process. For this reason, in the present invention, the outside of the insulating layer is wrapped in advance with a release tape made of tetrafluoroethylene to prevent moisture absorption, so that even if exposed to the atmosphere between the drying process and the resin injection process, the insulating layer will absorb moisture. I try not to. However, simply wrapping the outside of the insulating layer with release tape to prevent moisture absorption can achieve the purpose of preventing moisture absorption by preventing the insulating layer from coming into direct contact with the atmosphere, but it does not prevent the insulation layer from coming into direct contact with the atmosphere. The release tape has poor adhesion between the tape layers due to its releasing effect, and does not have the effect of retaining the resin injected into the insulating layer. Therefore, in the present invention, on the release tape wound on the outside of the insulating layer, an impregnated resin is further added.
Alternatively, insulation can be achieved by wrapping a tape with good adhesion properties, such as tetrafluoroethylene tape that has been treated with sodium to roughen its surface to improve resin adhesion, or a tape for preventing resin leakage such as non-woven fiber tape. In addition to not exposing the layer directly to the atmosphere, this prevents the injected resin from flowing out. In particular, when curing electric wire impregnated with resin in a heating furnace, the temperature initially rises as follows:
This is the insulation at the outermost periphery of the electric coil, which is in direct contact with the atmosphere of the heating furnace, and the resin in this area begins to harden and gradually progresses inside. Therefore, if the outermost layer is wrapped with resin-impregnated tape or tape that has good adhesiveness to resin to prevent resin spillage,
The resin in this tape to prevent resin leakage hardens first and forms a bag over the entire electrical wire ring, so the resin inside the insulation layer does not leak out of the insulation layer and a homogeneous insulation layer can be obtained. . Hereinafter, the present invention will be specifically described with reference to Examples. Example: A tape in which a composite material consisting of polyimide film (KAPTON manufactured by Dupont) and glass fiber as the main insulating material is treated with an imidazole-based catalyst (2PZ-CN manufactured by Shikoku Kasei), which is a curing catalyst for impregnated resin, around the electrical conductor. To prevent the resin impregnated into the main insulating material from coming into contact with air during the primary curing process, first wrap a half-wrap of tetrafluoroethylene tape as a release tape to prevent moisture absorption. Then, as a tape for preventing resin leakage, sodium-treated tetrafluoroethylene tape was wound once in a half-wrap, and dried under reduced pressure at 40°C and 0.1 mmHg.
After volatilizing water, etc., 100 parts by weight of bisphenol A type diglycidyl ether epoxy resin (DER332, manufactured by Dow) was added as a polyfunctional epoxy compound, and diphenylmethane diisocyanate (manufactured by Sumitomo Bayer, Inc.) was added as a polyfunctional isocyanate compound.
A resin containing 206 parts by weight of Sumidyur CD was vacuum impregnated and cured by heating. Heat curing conditions are 90
After primary curing at ℃ for 10 hours, after-curing was performed at 200℃ for 15 hours. After heat curing, release tape,
And the tape for preventing resin outflow was removed to obtain an electric wire ring. Example 4 As a release tape for preventing moisture absorption as described above
A fluorinated ethylene tape was wound once in a half-wrap, and a nonwoven fiber tape with good varnish impregnability (Vilene, manufactured by Nippon Vilene Co., Ltd.) was wound once on top of the tape in a half-wrap. Similar resin treatment and heat curing were performed. For comparison, only tetrafluoride ethylene tape was wrapped once in a half-wrap as a release tape for preventing moisture absorption around the outermost periphery of the insulating layer (as a comparative example), and a release tape for preventing moisture absorption, An electric wire ring was manufactured in the same manner as described above, without wrapping any tape for preventing resin leakage (comparative example). In order to compare the characteristics of each electric wire wheel manufactured in this way, the foaming state of the resin on the surface of the insulating layer, the amount of resin impregnation, BDV characteristics, and dielectric loss tangent were measured. The results are shown in the table below.

[Table] As is clear from the above table, in the comparative examples directly exposed to air, foaming on the surface of the insulating layer was significant, and therefore the electrical properties were not as good as in the examples. In addition, Comparative Example I, in which only a release tape for preventing moisture absorption is wound, shows some improvement compared to a Comparative Example in which no release tape is wound, but the electrical properties and the amount of resin impregnation are different from those in the example. inferior to. In the example, a lot of foaming occurred on the release tape for preventing moisture absorption and the tape for preventing resin leakage wrapped on top of the release tape, but since these tapes are removed after the resin hardens, the tape itself The foaming was not a particular problem, and no foaming remained in the desired insulating layer, and a homogeneous insulating layer with no leakage of the injected resin could be obtained, so the intended purpose was achieved. . According to the method for manufacturing an electrical insulating device of the present invention described above, an insulating material is wound on an electrical conductor to form an insulating layer, and a release tape for preventing moisture absorption is wrapped around the outside of this insulating layer. At the same time, a tape for preventing resin leakage is wrapped around the release tape and dried in a drying oven, and then impregnated with a resin containing a polyfunctional epoxy compound and a polyfunctional isocyanate compound as main components and cured by heating. , these release tapes and resin spill prevention tapes have been removed, so even if the insulating layer is exposed to the atmosphere after leaving the drying oven and entering the resin injection process, the insulating layer is still surrounded by the release tape. Since it is not directly exposed to the atmosphere, it does not absorb moisture, and therefore,
Foaming is prevented, and since there is a resin spill prevention tape, the resin in the resin spill prevention tape part hardens during heat curing and forms a bag over the entire electric wire ring, so the injected resin is insulated. Since these tapes do not flow out and are removed after the resin hardens, it is possible to obtain this type of electrical insulating device with improved insulation performance.

Claims (1)

[Claims] 1. An insulating material is wound around an electrical conductor to form an insulating layer, and then, through a drying process, the insulating layer is impregnated with a resin containing a polyfunctional epoxy compound and a polyfunctional isocyanate compound as main components. In the method for manufacturing an electrical insulating device formed by heating and curing, an insulating layer is formed on the electrical conductor, and then a release tape for preventing moisture absorption is wrapped around the outside of the insulating layer, and the release tape is An electrical insulation device characterized in that a tape for preventing resin spillage is wound on top and dried, then the resin is impregnated and cured by heating, and then the peeling tape and the tape for preventing resin spillage are removed. manufacturing method. 2. Claim 1, characterized in that a tetrafluoroethylene tape is used as the release tape for preventing moisture absorption, and a tetrafluoroethylene tape treated with sodium is used as the release tape for preventing resin outflow. A method of manufacturing the electrical insulation device described. 3. The method of manufacturing an electrical insulating device according to claim 1, wherein a tetrafluoroethylene tape is used as the release tape for preventing moisture absorption, and a nonwoven fiber tape is used as the tape for preventing resin outflow.