JPH057804B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a method for manufacturing an insulated wire by electrostatic powder coating. [Technical background of the invention and its problems] In recent years, the method of manufacturing insulated wires using powder coating has been attracting attention from the viewpoints of pollution-free, resource-saving, and energy-saving, and among these methods, this method has the highest coating efficiency. , the electrostatic dynamic dipping method is particularly gaining attention in the field of insulated wire manufacturing. In this method, for example, charged synthetic resin powder is fluidized by dry air passing through a perforated plate placed below to form a fluidized bed, and a metal conductor is filled with the synthetic resin powder above this fluidized bed. This is a method in which the synthetic resin powder is electrostatically attached to the surface through the coating zone, and then the attached synthetic resin powder is heated and fused and cured to form a coating. A method is used to pass the However, such a method has the disadvantage that a coating having a uniform thickness cannot be obtained over the entire circumference of the metal conductor, and therefore the dielectric breakdown voltage is low. [Purpose of the Invention] The present invention has been made to solve these problems, and it is an insulated wire that has a coating of uniform thickness over the entire circumference and has high electrical properties, especially dielectric breakdown voltage. The purpose is to provide a method for [Summary of the Invention] That is, the method of manufacturing an insulated wire using the electrostatic powder coating method of the present invention includes passing a conductor through a coating zone filled with charged synthetic resin powder,
In the method of manufacturing an insulated wire, the synthetic resin powder is attached to the surface of the conductor, and the attached synthetic resin powder is then heated and fused onto the conductor to form an insulating coating, wherein the insulating coating is a lower heat fused layer. It is characterized by forming an upper heat-sealing layer made of synthetic resin powder having lower flowability around the outer periphery of the holder. In the present invention, the heat-fused layer is formed in two or more layers, but the lower layer and the upper layer are coated with synthetic resin powder with different flowability, and in this case, the upper layer is formed with synthetic resin powder with low flowability. There is a need to. Even if a multilayer coating is formed using the same synthetic resin powder, uniformity of the coating cannot be obtained, and an improvement in dielectric breakdown voltage cannot be expected. Flowability can also be judged by gel time.
For example, when forming a coating in two layers, the lower layer has 200
It is preferable to use a synthetic resin powder having a gel time of 30 to 60 seconds at ℃, and similarly 5 to 20 seconds for the upper layer. In this case, if the gel time of the lower layer is less than 30 seconds, a uniform thin layer cannot be obtained, and if it exceeds 60 seconds, the reaction is slow and a long time is required for curing. On the other hand, if the gel time of the upper layer is less than 5 seconds, the reaction rate is too high, making it difficult to handle and resulting in poor appearance.If it exceeds 20 seconds, the coating thickness at the corners will be insufficient when applied to a rectangular conductor. It becomes uniform. [Embodiments of the Invention] Examples of the present invention will be described below. Example - Synthetic resin powder charged with a charging voltage of 65 kV is fluidized by dry air passing through a perforated plate at a flow rate of 300/min in a 70 cm long coating chamber to form a fluidized bed at the bottom of the coating chamber. I let it happen. From this fluidized bed about 10
cm horizontally 4.0 cm above the 2.0 x 5.0 mm rectangular copper wire
The charged synthetic resin powder was allowed to adhere to the surface by passing at a speed of m/min. Next, the rectangular copper wire with synthetic resin powder attached to its surface was heated in a furnace at a temperature of 400 to 500℃ and a length of furnace.
The synthetic resin powder was passed through a 3.5 m heating furnace at a speed of 4.0 m/min to heat-fuse and further harden. The above process was repeated twice, the first time using Sumilight Resin PR-E-8688 (product name manufactured by Sumitomo Durez Co., Ltd.) as the synthetic resin powder, and the second time using Aron Powder EZ-1165 (trade name manufactured by Toagosei Chemical Co., Ltd.). product name)
Table 1 shows the measured values of the coating thickness and dielectric breakdown voltage at each position shown in the figure of the rectangular insulated wire obtained using the method. In the figure, 1 represents a rectangular copper wire, and 2 represents an insulating coating.

【table】

【table】

[Table] In addition, those shown as Comparative Example 1 in Table 1 are as follows:
Sumilite Resin PR-E- as a synthetic resin powder
8688 was used, and the film was formed in one step in the same process as in the example.Comparative example 2 uses the same synthetic resin powder as in comparative example 1, and the other cases are the same as in the example. A case is shown in which a film is formed by repeating the same process twice. Table 2 shows the characteristics of the synthetic resin powder used in the Examples and Comparative Examples. As is clear from the above measurement results, by forming a heat-fused layer made of synthetic resin powder with lower flowability in the upper layer than in the lower layer, a film with a more uniform thickness can be formed compared to the conventional method. Its dielectric breakdown properties are also improved. [Effects of the Invention] As is clear from the above examples, according to the present invention, an insulating film having a uniform thickness is formed all around the conductor, and therefore an insulating film with excellent electrical and mechanical properties can be obtained. Electric wires can be manufactured.

[Brief explanation of the drawing]

The drawings are cross-sectional views for explaining the measurement positions of coating thickness in Examples and Comparative Examples of the present invention. 1...Flat copper wire, 2...Insulating coating.

Claims (1)

[Claims] 1. The conductor is passed through a coating zone filled with charged synthetic resin powder to adhere the synthetic resin powder to its surface, and then the adhered synthetic resin powder is heated and fused onto the conductor to insulate it. In the method for producing an insulated wire in which a coating is formed, the insulating coating is formed by forming an upper heat-fusion layer made of synthetic resin powder having lower flowability than the lower heat-fusion layer on the outer periphery of the lower heat-fusion layer. A method of manufacturing insulated wire using electrostatic powder coating method.