JPS6137728B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a film for covering electric wires, which is a laminated film of phenoxy resin and plastic film. In the case of thin wires, the wires are often simply coated with a resin such as vinyl chloride resin, but in the case of thick wires, an insulating film is often wrapped around the outside and then a resin coating is applied. Conventionally, as this insulation coating film,
Polyethylene terephthalate film, polyethylene film, polypropylene film, nylon film, etc. are used, but among these films, most of these films other than polyethylene film have no self-bonding properties, and are made to adhere by heat shrinkage stress due to heat treatment, or A method has been adopted in which a polyethylene laminated film is wrapped around these films and then heat-sealed. However, in these methods, the adhesion between the film and the copper wire is weak, and gaps are often formed between the film and the copper wire, resulting in a decrease in insulation performance. As a result of extensive research into this problem, the present inventors came up with the following laminated film for covering electric wires. That is, it is a laminate film for covering electric wires, which is a laminate of a phenoxy resin and a plastic film having the following structural formula. The phenoxy resin used in the present invention is made by polymerizing bisphenol A and epichlorohydrin,
It softens at about 100℃ and can be heat-fused. Methods for producing a laminated film of plastic film and phenoxy resin include a coating method in which a phenoxy resin solution is applied to a plastic film and then dried, a method in which a plastic film and a phenoxy resin film are dry laminated, and a method in which a phenoxy resin solution is applied to a plastic film and then dried. Examples include an extrusion lamination method in which a resin is extruded and pressed, and a method in which a plastic resin and a phenoxy resin are co-extruded, but the method is not particularly limited to these. Although the phenoxy resin layer may be formed on only one side of the plastic resin layer, it is preferable to form it on both sides to ensure complete adhesion. Furthermore, either or both of the plastic resin layer and the phenoxy resin layer may be stretched. Further, if a slip property improver such as inorganic particles is added to these layers, the workability will be very good. Although the type of plastic film is not particularly limited, the use of biaxially oriented polyethylene terephthalate film or biaxially oriented polypropylene film is particularly favorable in terms of workability, electrical performance, and economy. In addition, the thickness of the phenoxy resin layer is 1 to
3μ is preferred. Coating of electric wires with the laminated film of the present invention is carried out by first micro-slitting the laminated film produced by the above method, and then wrapping the slit film around the copper wire. The width of the slit in the film must be changed depending on the thickness of the copper wire, the thickness of the laminated film, and the strength of the film. It can be rolled up while adhering well. The copper wire coated in this manner is heated in the next step to fuse the films together and the films and the copper wire, thereby making it possible to create an integrated electric wire. Alternatively, there is also a method of coating the outside with another molten resin and fusion using the heat of this resin. Furthermore, when used in a coil or the like, it is possible to integrate the coated wires by winding them next to each other and then heating and fusing them together. With conventional wire coating methods, the adhesion between the copper wire and the coating film was poor, and the adhesion between the coating films was also poor, making it impossible to prevent moisture from entering and causing problems in maintaining insulation performance. When a laminated film for covering electric wires is used, the adhesion between the copper wire and the film and between the films is very good, making it possible to prevent moisture from entering. In addition, in the case of a coil or the like, it is possible to prevent the winding from breaking, making the subsequent steps very easy. In the case of the laminated film of the present invention, the adhesion is slightly inferior to that of a film made of phenoxy resin alone, but due to the characteristics of the plastic film as a carrier, heat resistance, voltage resistance, workability, etc. can be improved.
For example, when biaxially stretched polyethylene terephthalate film is used as a carrier, it has a higher melting point, higher voltage resistance, and higher Young's modulus than phenoxy resin, so heat resistance, voltage resistance, winding workability, etc. are significantly improved. . Hereinafter, more details will be described with reference to Examples. Example A phenoxy resin was dissolved in a mixed solvent of toluene and ethyl acetate to prepare a solution having a concentration of 15% by weight. The solution was coated on both sides of a biaxially stretched polyethylene terephthalate film with a thickness of 23 μm using a gravure roll method and dried. The thickness of each coated phenoxy resin was 1.5μ. The laminated film was microslit to a width of 6 mm and wound onto several bobbins. This microslit film was wound around a copper wire in a helical manner so that the ends were slightly overlapped, passed through a hot air oven at 140°C to fuse it, and then cooled and wound up. The electric wire manufactured in this way is heated to 95% at 40℃.
After being left in RH for 500 hours, changes in withstand voltage were measured, and as shown in Table 1, almost no deterioration was observed and the results were good. 【table】

Claims (1)

[Claims] 1. A laminate film for covering electric wires, which is a laminate of a phenoxy resin and a plastic film having the following structural formula. 2. The laminated film for covering electric wires as set forth in claim 1, wherein the plastic film is a biaxially stretched polyethylene terephthalate film. 3. The laminated film for covering electric wires as set forth in claim 1, wherein the plastic film is a biaxially stretched polypropylene film.