JPS5917484B2 - Manufacturing method of insulated wire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method of manufacturing polyester resin insulated magnet wire.

5 Currently, magnet wires insulated with polyester resin use aromatic dicarboxylic acids such as terephthalic acid as the main component of the polycarboxylic acid component, and a polyhydric alcohol component containing polyhydric alcohols of trihydric or higher valence. A thermosetting polyester resin obtained by reacting with is dissolved in an appropriate amount of an organic solvent to form a paint, which is applied onto a conductor and baked several times at a temperature of 300°C or higher. Manufactured using a repeated application method.

,,0,=゛1:;:::::::1 - It is common to adjust the viscosity using a relatively large amount of solvent.

Solvents used for this purpose include phenols such as phenol, cresol, and xylenol, to which xylene and solvent naphtha are added as diluents, but these solvents are highly toxic and difficult to recover. Currently, it is not possible to do this fully, and some of it is burned and emitted.

Therefore, from the viewpoint of improving the working environment and saving resources, solvent ■5
There was a strong desire for a method of manufacturing magnet wire without using. In response to these demands, we developed a nonlinear polyester resin that can be cured by free hydroxyl groups at 100°C.
Manufactured by applying heat and melting to a certain degree and baking by heating.
A method (Japanese Patent Publication No. 51-24704) has been attempted.

The resin used in this case must be one that has been condensed to such an extent that substantially no condensation reaction occurs when melted. On the other hand, if 5 resin is used for high condensation in order to give the obtained magnet wire sufficient properties, melt coating becomes difficult, so a small amount of solvent must be added, but this does not meet the original purpose. It was out of place. Furthermore, as seen in Japanese Patent Laid-Open No. 53-4875, attempts have been made to simply extrude and coat linear thermoplastic resins such as polyethylene terephthalate and use them as magnet wires or wiring materials for equipment. However, when coated wires obtained by simply extrusion coating these resins are used as magnet wires, the following drawbacks have been found. In other words, since these resins are crystalline polymers, when the coated wire is stretched or bent during coil processing, microscopic cracks, so-called crazing, occur in the coating, degrading the electrical properties, and drying. Therefore, even when the coating was heated at a temperature below its melting point, loss of flexibility due to crystallization of the coating resin was observed.

In addition, as a test method for heat deterioration resistance of enameled wire, JISC3
In the method of observing the flexibility after heating for a predetermined time specified in 2O3, 32lO, 32ll, etc. (for example, in the case of polyester enamelled copper wire, the flexibility after heating at 200°C for 6 hours) is also determined by the crystallization of the coating resin. This results in a complete loss of flexibility.

The inventors conducted extensive research on a method of obtaining a polyester resin-insulated magnet wire without using solvents and without the above-mentioned drawbacks. After melt-coating a linear polyester resin on a conductor, the inventors further investigated a method of obtaining a polyester resin-insulated magnet wire without using solvents and without the above-mentioned drawbacks. Apply polyol,
After that, this coated wire is heat-treated in the conventional manner, and three-dimensional network bonding occurs in the resin film of the insulated wire, and this resin film no longer exhibits the above-mentioned crazing phenomenon and can be coil-wound. Therefore, an insulated wire with sufficient properties as a magnet wire can be obtained, and the appearance of the obtained insulated wire is significantly improved and the cured film is improved compared to the case where the insulated wire is simply heated without applying a trivalent or higher valent polyol. By using linear polyester resin and trivalent or higher valent polyol, which have been conventionally applied to films, fibers, molded products, etc., we discovered that the production speed was significantly faster and the electrical properties were significantly improved. The present invention was achieved by discovering that it is possible to obtain an insulated wire that has the necessary properties comparable to conventional magnet wires insulated with polyester resin. That is, in the method of the present invention, a linear polyester resin mainly formed from aromatic dicarboxylic acid residues and aliphatic glycol residues is coated onto a conductor by melt coating or extrusion coating, and then further coated on this coated conductor. It is characterized by coating a polyol with a valence of 3 or more and then heating it.

As mentioned above, in the conventional method using a solvent, the amount of paint applied at one time is limited due to the volatilization of the solvent and reaction products in the coating and baking process for forming a film, for example, a diameter of 1.0 m7! When using L conductors, it was necessary to repeat coating and baking the paint at least three times, but with the method of the present invention, one coating or coating and heating is sufficient to form a film that can be used for practical purposes as a magnet wire. It has a number of characteristics, such as being able to form a polyol, significantly improving the appearance of the insulated wire obtained by applying the polyol, and curing the formed film extremely quickly, making it possible to significantly increase the manufacturing speed. Examples of the polyester resin mainly formed from aromatic dicarboxylic acid residues and glycol residues in the present invention include polyethylene terephthalate (PET) resin, polybutylene terephthalate (PBT) resin, polyethylene naphthalate resin, etc. In order to improve its physical properties, it can be copolymerized with different dicarboxylic acids or glycols.

In addition, the method for coating the linear polyester resin mentioned above includes a melt coating method in which the resin is heated to a molten state and the conductor is immersed in the resin, or a method in which the resin is melted in an extruder and extruded to coat the conductor. Extrusion coating is the most preferred coating method from an economical point of view.

The feature of the present invention is that after the conductor is coated with a linear polyester resin in a solvent-free state, a polyhydric alcohol of trivalent or higher valence is further applied onto the coated wire, and then heated and cured.

Trivalent or higher polyols used for this purpose include:
Glycerin, trimethylolpropane, trimethylolethane, pentaerythritol, etc. can be used, and those that are solid at room temperature can be melted and applied by heating.

Among them, glycerin is particularly preferred because it is inexpensive and can be removed in liquid form at room temperature, making it easy to handle. In addition, when applying this polyol having a valence of 3 or more, it is desirable to expose the coated object to ultrasonic waves using an ultrasonic oscillator immediately after applying the polyol, as this has the effect of significantly promoting crosslinking during the heat curing reaction of the coating film. It is something.

Examples will be described below.

Example 1 Polyethylene terephthalate resin manufactured by Teijin, trade name TR
-4550SH (hereinafter referred to as PET).

A copper wire with a diameter of 0.85m7fL is passed through a tank heated to 270℃ (melting point 250-260℃), and squeezed with a die at the exit to form a 22μ coating film. Glycerin was applied, and the coated line was then passed through a furnace with a furnace length of 5 m and a furnace temperature of 450°C in an air atmosphere for 5 m/min.
An insulated wire was obtained by passing the wire at a speed of 1 minute. Comparative Example 1 Using the same PET as in the example, a coating film was formed under the same conditions, and immediately heat-treated in the same manner as in the example without applying glycerin.

Example 2 Using the same PET as in Example 1, a coating film was formed under the same conditions, and then glycerin was further applied, ultrasonic waves were applied, and then heat treatment was performed in the same manner as in Example.

Claims (1)

[Claims] 1. After coating a conductor with a linear polyester resin mainly formed from aromatic dicarboxylic acid residues and aliphatic glycol residues by melt coating or extrusion coating method, a trivalent or higher valent polyol is applied onto the coated conductor. 1. A method for producing an insulated wire, the method comprising coating the insulated wire with the following steps: