JPS61200618A - Manufacture of insulated wire - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method of manufacturing an insulated wire using a powder coating method.

[Prior art]

Recently, due to the popularity of powder coating methods, a method of manufacturing insulated wires by forming an insulating film on a conductor is being used in some cases. This powder coating method is advantageous in terms of saving resources and energy because it is solvent-free, and because it can obtain a thick coating film with one coat, it is sufficient to apply one coat, and there is uneven thickness. It has various advantages such as less

However, the insulation film formed by this powder coating method tends to have voids (defects) inside because it forms a thick film on the 1R or because the resin does not flow sufficiently when heated and melted. . Therefore, the dielectric strength of the insulating film obtained by the powder coating method is significantly lower than that of general enamelled wire.

In other words, the breakdown voltage of MA edge wires with general-purpose solvent-based insulating paint is 2 to 5 T (V/10 μm,
For those using powder coating method, α1~I KV/10μm
It is low and the variation is large.

For this reason, insulated wires obtained by powder coating have an insulation film thickness that is 1.5 to 1.5 times thicker than that of general enamel insulated wires.
A method has been taken to compensate for the low dielectric strength by making the wire about twice as strong, but even in this state, the dielectric breakdown voltage value is still unsatisfactory, being about 50 to 70% that of general enamelled wire.

[Purpose of the invention]

This invention was made in view of the above circumstances, and it is possible to form an insulating film with a high P3 edge strength using a powder coating method, and to manufacture an insulated wire that can reduce the thickness of the P3 edge coating. The purpose is to provide a method.

[Structure of the invention]

The method for manufacturing an insulated wire according to the present invention is such that the thickness of the insulating film obtained by one powder coating is 50 μm or less.

[Technical aspect of the invention, JISi111] When forming an insulating film using a powder coating method, the present inventors varied the thickness of the film in one coating, and investigated the degree of occurrence of voids in the film due to this process. Considered changes. As a result, as shown in Figure 1, when the thickness of the film formed by one coating exceeds 50 μm, the voids in the film suddenly increase by 1 cMt, while below 50 μm, there is a slight film thickness dependence. We have found an experimental fact that the number of voids decreases when the voids are damaged. This experimental result was obtained using an epoxy resin having an average particle size of 10 to 70 μm as a powder resin. The data in Figure 1 is based on the diameter I Im
Insulating layers were formed on steel wires of various thicknesses by powder coating, and the number of voids with a diameter of 10 μm or more observed per insulating layer was determined.

[Specific structure of the invention]

As the powder coating method used in this invention, a normal electrostatic powder coating machine is used. In other words, pickling the conductor surface,
After performing cleaning treatments such as degreasing, this conductor is introduced into an electrostatic powder coating machine, which uses resin powder such as epoxy powder, polyamide powder, or polyester powder, and applies a high voltage to this powder at room temperature. The powder particles are charged with electric charge, the particles are attached to the surface of the conductor by electrostatic force, and the particles are introduced into a heating furnace and heated to melt the powder and form an insulating film.

According to the present invention, the film thickness obtained by one coating is 50 μm or less, preferably in the range of 20 to 50 μm. In the general powder coating method, 10 to 2
It is characterized by the fact that a thick coating film of about 0.00 μm can be obtained, but such a thick coating has many voids as described above and is not suitable as an insulating coating. On the other hand, if the thickness is less than 20 .mu.m, although voids are less likely to occur, the number of coatings necessary to obtain a predetermined film thickness increases, which is inconvenient and increases manufacturing costs. If it exceeds 50 μm, there will be many voids (as mentioned above), which will be inconvenient.
Since it is set to 0 μm or less, the specified insulation film thickness is 50 μm.
If the thickness exceeds 100, the number of times of coating may be increased to two or more times to obtain the required thickness. Further, the thickness of one coat can be adjusted within the range of 20 to 50 μm by appropriately adjusting the applied voltage, the amount of air, the transfer speed of the conductor, and the like.

Further, in the present invention, the insulating film can be obtained by combining powder coating and ordinary solvent-based insulating coating. In this case, the film thickness from one powder coating is, of course, 5.
It shall be 0 μm or less. In addition, when performing this combination coating, it is convenient in terms of the structure of the coating device to apply the solvent-based insulating coating to the innermost or outermost layer of the insulating film.

Furthermore, the powder resin used in this invention includes thermosetting resins such as epoxy resin, polyester resin, acrylic resin, urethane resin, polyamide fII resin, vinyl chloride resin, polyethylene durable layer, fluororesin, and polyether ether ketone resin. and thermoplastic resin particle size 10-70
μ＠I7)＠Gold powder Song can be used alone or in a suitable combination of two or more powders. Since the thickness of the insulating film by painting is 50μm or less,
The resulting film has few voids and has high dielectric strength. Therefore, the thickness of the insulating film can be made thinner than that obtained by conventional powder coating methods.
Although the number of coats increases, overall manufacturing costs do not increase.

〔Example〕

``Implementation f! AUI J'' Powder coating a copper wire with a diameter of 0.1π with epoxy resin powder (manufactured by 3M, USA) three times in total so that the thickness of each coat is 20 μm, and then An insulated wire having an insulation film with a thickness of 60 μm was obtained.

"Example 2" Epoxy resin powder was powder coated once to a thickness of 20 μm on a copper wire having a diameter α1u, and then polyetheretherketone resin powder (manufactured by ICI, UK) was coated once on top of this. Powder coated twice with a coating thickness of 20μm, total coating thickness of 60μm.
An insulated wire having an insulation film of m was obtained.

"Example 3" Epoxy resin powder was powder coated twice on a steel wire with a diameter of α1 at a coating thickness of 240 μm to form a 40 μm film, and then polyester imide varnish (Nippon Shokubai Schenectady Co., Ltd.) was applied and baked to a coating thickness of 5 μm, &1! Insulation 1 with an insulation film of 5μm thick paulownia! tM was obtained.

"Comparative Example 1" An insulated wire was obtained by forming an insulating film with a thickness of 120 μm on a copper wire having a diameter α1 by applying epoxy resin powder once.

"Comparative Example 2" One layer of epoxy resin powder was placed on tfiJj with a diameter of 11 m'l.
The powder coating was applied twice to form an insulating film with a thickness of 60 μm, resulting in a ``C'' insulated wire.

"Comparative Example 3" A polyester imide varnish was applied onto a copper wire having a diameter of α1 and baked to obtain an insulation 1 wire having an insulation film with a thickness of 35 μm.

The characteristics of these six insulated wires were measured and studied. The results are shown in Table 1.

Table 1 Note 1) Conforms to JIS-C-3003 & 1.1K.

2) Conforms to JIS-C-50039, 1.

3) Conforms to JIS-C-500311, D2 twist method).

As is clear from Table 1, the insulated wire according to the present invention has an extremely high dielectric strength voltage compared to the conventional powder-coated insulated wire. It can be seen that it has It is also understood that the insulation voltage per unit thickness is approximately the same as that of conventional enamelled wire.

〔Effect of the invention〕

As explained above, in the method for manufacturing an insulated wire of the present invention, the insulation coating is formed so that the thickness of the coating is 50 μm in one coating, so there are no voids (defects) in the insulation coating. ) is extremely small (becomes), thereby greatly improving dielectric strength.

Therefore, the thickness of the insulating film can be reduced to almost the same thickness as a conventional enamel varnish coated insulated wire, and material costs can be significantly reduced.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between the thickness of one powder coating and voids, which shows the technical basis of the manufacturing method of the present invention. Figure 1 Hiroku thickness σt)tm)

Claims (1)

[Claims] A method for manufacturing an insulated wire, which comprises forming an insulating film on the surface of a conductor by powder coating, and reducing the thickness of the insulating film by one powder coating to 50 μm or less.