JPH0366767B2 - - Google Patents

Description

[Detailed description of the invention]

(Technical Field of the Invention) The present invention particularly relates to a self-bonding insulated wire with excellent heat resistance and a method for manufacturing the same. (Technical Background of the Invention) Conventionally, in order to shorten the process of forming coils for electrical and communication equipment, a heat-adhesive layer made of thermoplastic resin such as polyvinyl butyral resin or polyamide resin has been applied on a conductor via an insulating layer. So-called self-bonding insulated wires are widely used. Such a self-bonding insulated wire has the advantage that it is generally not necessary to perform an impregnating treatment with an insulating varnish because the coating is softened and fused and integrated by simply heating after coil forming. (Problems in the Background Art) However, in conventional self-bonding insulated wires, the heat resistance of the bonding layer itself is low, and if an overload current flows through the coil or if it is placed in a high temperature atmosphere, However, there was a drawback that the fusion strength was significantly reduced. Furthermore, since the insulating layer and the adhesive layer are usually formed of different resin paints with different coating and baking conditions, they cannot be coated and baked continuously, resulting in low productivity. (Object of the Invention) The present invention was made in order to eliminate these drawbacks, and its purpose is to provide a self-bonding insulated wire with excellent heat resistance and a method for efficiently and continuously manufacturing the same. do. (Summary of the Invention) That is, the present invention comprises a conductor made of an aromatic polyimide resin soluble in a phenolic solvent, either directly or through another insulating layer, and the phenolic solvent is added in a proportion of 30 to 65% by weight. A self-adhesive insulated wire characterized by having a fusion layer containing the same, and an insulated wire obtained by applying and baking an aromatic polyimide resin paint using a phenolic solvent on a conductor multiple times. The insulating layer is baked and cured almost completely by passing it through a baking oven once or several times in succession, and then the aromatic polyimide resin paint is applied thereon to a predetermined thickness and baked at low temperature and high speed. This is a method for manufacturing a self-bonding insulated wire. In the self-fusing insulated wire of the present invention, the aromatic polyimide resin soluble in the phenolic solvent constituting the fusing layer is, for example, 3,3',4,4'-benzophenonetetracarboxylic acid (hereinafter referred to as BT). ) (including its anhydride and lower alkyl ester) and 3,3'-diaminodiphenyl sulfone;
A diamine component mainly composed of diamines with a special structure such as 3,3'-diaminodiphenyl ether, metaxylylene diamine, and paraxylylene diamine is used in a phenolic solvent such as cresol in a sufficient amount to complete the imide ring-closing reaction. It is obtained by a heating reaction at a temperature and time. The adhesive layer contains the phenolic solvent in an amount of 30 to 65% by weight of the entire layer by adjusting the temperature and speed of baking the resin paint. The reason why the amount of phenolic solvent remaining in the adhesive layer is limited to this range is that if the amount of residual solvent is less than 30% by weight, the fusion property is insufficient, whereas if it exceeds 65% by weight, the flexibility is poor. This is because it is insufficient and cannot be put to practical use in either case. In addition, in order to efficiently and continuously manufacture such a self-bonding insulated wire in the present invention, the phenolic solution (paint) of the aromatic polyimide resin is applied 3 to 6 times directly onto the conductor, and the process is relatively easy. After baking at a low temperature, the insulating layer is passed through a baking oven 1 to 3 times to almost completely bake and harden it until the amount of residual solvent is 10% by weight or less, and then the same aromatic polyimide as above is applied on top of it. It is desirable to apply a resin solution 2 to 4 times and bake at low temperature and high speed. By adopting this manufacturing method, the insulating layer and the fusion layer are composed of resins with the same chemical composition, and have high fusion properties, with self-bonding properties that hardly reduce the fusion strength even in high-temperature atmospheres. An insulated wire is obtained. (Examples of the invention) Examples of the invention will be described below. Examples 1 to 6 First, cresol solutions of aromatic polyimide resins were prepared by the following method. (Preparation of aromatic polyimide resin solution) 32.2 g (0.1 mol) of BT (dianhydride) and 3,3'-dimethyl-4,4'-diaminodiph were placed in a three-necked flask equipped with a temperature, stirrer, and condenser. 22.8 g (0.1 mol) of enylmethane and 145 g of metacresol were charged simultaneously, and heated with stirring to raise the temperature from room temperature to 160°C. Water gradually begins to come out of the reaction system, and the solution gradually becomes transparent. The mixture was heated and stirred for about 1 hour, and the reaction was stopped when water stopped distilling out. Acetone was gradually added to the resin solution thus obtained to precipitate the resin, which was washed and dried under vacuum at room temperature to obtain 48.8 g (yield: 95%) of a pale yellow polyimide resin. The solid content of this cresol solution of aromatic polyimide resin was 15.2% by weight, and the viscosity at room temperature was 52 poise. Next, the solution obtained in this way was applied to a type of insulated wire made of an annealed copper wire with an outer diameter of 1.0 mm and a polyimide resin insulating layer of 30 μm in the thickness shown in Table 1. A baked self-bonding insulated wire was produced by passing it through a baking furnace at 350°C at the wire speed shown in the same table. The excessness and dielectric strength of the obtained self-fusing insulated wire and the amount of cresol remaining in the fusing layer were measured. In addition, after molding on a coil, the adhesive layer is fused and integrated by heating under the conditions shown in Table 1.
NEMA welding strength at room temperature and high temperature atmosphere
Measured in accordance with Part 3.57. The results of these measurements are also shown in Table 1. In addition, as Comparative Examples 1 and 2, the same cresol solution of the aromatic polyimide resin as in Examples 1 to 6 was applied onto the type 1 insulated wire, and the same furnace was heated at a line speed of 14 m/s.
An insulated wire was manufactured by baking the wire at a speed of 40 m/min and 40 m/min. The characteristics of these insulated wires, conventional phenoxy resin-based self-bonding insulated wires, and polysulfon resin-based self-bonding insulated wires were measured in the same manner as in the examples. The results of these measurements are also shown in Table 1.

[Table] *2. Trade name of polysulfone resin from the same company. *3. Compliant with NEMA 1000 Part 3.57 Example 7 The cresol solution of the aromatic polyimide resin used in Examples 1 to 6 was poured into a 1.0 mm diameter After coating and baking six times on annealed copper wire under the following conditions to form a coating film with a thickness of 35 μm, the insulating layer was further passed through a baking oven twice under the same conditions to completely harden the insulating layer. Baking furnace length: 6 m Furnace temperature: 350°C Linear speed: 24 m/min Next, on top of this insulating layer, a cresol solution of the same aromatic polyimide resin was applied and baked three more times under the same conditions as above, to form a 15 μm thick molten layer. An adhesion layer was formed. As a result of measuring the amount of cresol remaining in the insulating layer and the fusion layer of the self-bonding insulated wire thus obtained, the following values were obtained. Insulating layer: 8.5% by weight Fusion layer: 52% by weight The electrical and mechanical properties of this insulated wire were also measured. The measurement results are shown in Table 2. Furthermore, after forming this insulated wire into a coil shape,
The fusion bond strength was measured in accordance with NEMA 1000 Part 3.57 for a product whose fusion layer was fused and integrated by heating at a temperature of 240° C. for 1 hour. The measurement results are also shown in Table 2.

【table】

[Table] (Effects of the Invention) As is clear from the above examples, the self-bonding insulated wire of the present invention not only has good electrical and mechanical properties, but also has good fusing strength, especially in a high-temperature atmosphere. Due to its excellent fusing strength, it is suitable as an electric wire for forming coils in various electrical devices. Furthermore, according to the manufacturing method of the present invention, such a self-bonding insulated wire can be efficiently and continuously obtained.

Claims (1)

[Scope of Claims] 1. A fusion bond made of an aromatic polyimide resin soluble in a phenolic solvent and containing the phenolic solvent in a proportion of 30 to 65% by weight, directly on the conductor or via another insulating layer. A self-bonding insulated wire characterized by having layers. 2 After applying and baking an aromatic polyimide resin paint using a phenolic solvent as a solvent on the conductor multiple times, the resulting insulated wire is passed through a baking oven once or several times in succession to bake the insulating layer almost completely. 1. A method for producing a self-bonding insulated wire, which comprises curing the coating, then coating the aromatic polyimide resin coating thereon to a predetermined thickness, and baking at low temperature and high speed.