JPH06231616A - Insulated wire for coil - Google Patents

Abstract

PURPOSE:To prevent wrinkles or the like from generating upon wrapping in an insulated wire for coil composed of conductor and an insulating layer covering outer circumference thereof by using an insulating layer made of crosslinked body of ethylene-fluolefin copolymer and having a specified value in M30 of the crosslinked body. CONSTITUTION:In a coil insulate electric wire composed of conductor and an insulating layer covering the outer circumference thereof the layer is formed of crosslinked body of ethylene-fluolefin copolymer. The M30 value of the crosslinked body should be 3.1kg/mm<2> or more. If the M30 value is less than 3.1kg/mm<2>, many wrinkles are generated on the insulating layer upon wrapping. This layer is formed by a method wherein crosslinking agent is mixed into ethylene-fluolefin copolymer to form a mixed compound, with which the surface of conductor is extrusion coated, and the extrusion coated layer is irradiated with radiation for promoting the corsslinking reaction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulated wire for a coil, and more particularly to an insulated wire for a coil covered with an insulating layer which causes less wrinkles when the coil is processed.

[0002]

2. Description of the Related Art Coil moldings used in electrical and communication equipment are generally manufactured by winding insulated wires in a predetermined shape, impregnating them with varnish, and bonding and fixing the wires to each other. ing. For example, in the case of an eddy current preventing breaker used in household and industrial power distribution equipment, a cotton winding is used, and after the winding, varnish impregnation is performed to manufacture a coil molded body.

However, in the case of the coil using the cotton winding, the process required for manufacturing the coil is long and the workability at the end treatment after molding is poor. Therefore, in place of the above-described cotton winding, it is considered to manufacture a coil using a covered electric wire in which the surface of the conductor is covered with an insulating layer.

[0004]

However, in the case of the insulated wire for coil proposed hitherto, when the wire is wound around the mandrel, a stretching force is generated outside the insulating layer,
Since a compressive force acts on the inner side, generally, many wrinkles are generated in the insulating layer on the mandrel side, and the defective rate of the coil molded body increases.

This is a phenomenon caused by the inner insulating layer being pushed out by the compressive force when wound on the mandrel. The present invention solves the above-mentioned problems in a conventional insulated wire for a coil covered with an insulating layer, suppresses the generation of wrinkles during winding, and therefore has a low insulation failure rate for a coil. The purpose is to provide insulated wires.

[0006]

In order to achieve the above-mentioned object, in the present invention, in an insulated wire for a coil comprising a conductor and an insulating layer covering the outer periphery of the conductor, the insulating layer is ethylene-fluoro. It consists crosslinked olefin copolymer, and, M ₃₀ value of the crosslinked material is 3.1 kg / mm
There is provided an insulated electric wire for a coil, which is characterized by being ² or more.

The insulated wire for a coil according to the present invention has an insulating layer
It has characteristics. That is, first, the insulating layer is ethylene-
It is composed of a cross-linked fluoroolefin copolymer.
M ₃₀Value is 3.1kg / mm²That is all. Ethyl used
Examples of the styrene-fluoroolefin copolymer include, for example,
Ethylene-tetrafluoroethylene copolymer, ethylene
-Chlorotrifluoroethylene copolymer, or both
A mixture can be given.

The M ₃₀ value is determined by the tensile strength at 30% elongation when the elongation (%) is measured at a test speed of 50 mm / min according to ASTM D638. That is, the M ₃₀ value represents the resistance force when the insulating layer of the crosslinked body is stretched by 30%, which corresponds to the compressive force generated in the insulating layer when wound on the mandrel. According to our research
More specifically, it shows the rate at which the insulating layer is compressed when the electric wire is wound on a mandrel having a diameter twice that of the electric wire. That is, the M ₃₀ value is a scale representing the ease of winding when the winding diameter at the time of winding is not less than twice the diameter of the electric wire.

In the insulated wire for coils of the present invention, the M ₃₀ value of the insulating layer is set to 3.1 kg / mm ² or more. This M ₃₀
This is because when the value is lower than 3.1 kg / mm ² , many wrinkles are generated in the insulating layer during winding. This insulating layer is preferably formed as follows. For example, a method of admixing the above-mentioned ethylene-fluoroolefin-based copolymer with a crosslinking accelerator, extrusion-coating the conductor surface with the resulting admixture, and then irradiating the extrusion-coated layer with radiation to promote the crosslinking reaction. Is.

Preferred examples of the crosslinking accelerator used at this time include allyl type compounds such as triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate and tetraallyl pyromellitate. . Further, the amount of the crosslinking accelerator compounded is preferably 5 to 10 parts by weight with respect to 100 parts by weight of the ethylene-fluoroolefin copolymer. If the blending amount is less than 5 parts by weight, the effect of promoting cross-linking becomes insufficient and the generation of wrinkles during winding is not sufficiently suppressed, and if it is more than 10 parts by weight, the ethylene-fluoroolefin copolymer and This is because it becomes difficult to mix them uniformly.

If necessary, known inorganic fillers, antioxidants, colorants and the like may be added to the above-mentioned admixture composition in appropriate amounts, and tetrafluoroethylene-propylene copolymer and You may mix | blend other fluororesins, such as polyvinylidene fluoride. The outer periphery of the conductor is extrusion-coated with the admixture composition thus prepared, and then the coating layer is irradiated with ionizing radiation such as electron beam or γ-ray.

If the radiation dose at this time is too large, the obtained crosslinked product deteriorates, so it is appropriate that the radiation amount be 40 Mrad or less. However, if the radiation dose is too low, the crosslinking does not proceed sufficiently and the above-mentioned M ₃₀ value does not exceed 3.1 kg / mm ² , so it is preferably 25 to 30 Mrad. This radiation irradiation is usually performed at room temperature,
You may perform in a higher temperature atmosphere.

The thickness of the insulating layer is preferably 0.5 mm or less. It is more preferably 0.4 mm or less. Thickness is 0.5
This is because if the thickness is larger than mm, the flexibility of the insulating layer is reduced and it is difficult to wind the mandrel. Further, this insulating layer may be one layer, but may be two or more layers.
In that case, at least the outermost insulating layer, the M ₃₀ value
Form it so that it is 3.1 kg / mm ² or more.

[0014]

Examples of the invention

Examples 1 to 6, Comparative Examples 1 and 2, the zone from the raw material charging part to the crosshead part was 270 ° C,
The temperature was controlled in three stages of 305 ° C and 325 ° C, the temperatures of the crosshead part and the die part were both controlled to 280 ° C, the screw rotation speed was 10 rpm, the L / D was 24, and the compression ratio was 3. The components shown in Table 1 were put into an extruder at the indicated ratio (parts by weight) and mixed, and the mixed composition was extrusion-coated on a conductor having an outer diameter of 3.26 mm preheated to 140 ° C. Two coating layers were formed. The thickness of the first coating layer is 0.1 mm, the thickness of the second coating layer (outer layer) is 0.15
mm.

[0015]

[Table 1]

Each coated electric wire was irradiated with an electron beam at the irradiation dose shown in Table 2 to crosslink the coating layer. The M ₃₀ value and the M ₁₀₀ value of the outer layer of the obtained electric wire were measured, and each electric wire was wound around a mandrel having a diameter of 7 mm and 14 mm, and when wrinkling was doubled and quadrupled. The number of occurrences was visually observed.

The number of wrinkles was visually measured. The above results are collectively shown in Table 2.

[0018]

[Table 2]

[0019]

As is apparent from the above description, the insulated wire for a coil of the present invention has almost no wrinkles in the insulating layer when the coil is processed, and the appearance of the coil molded body is good. This is an effect brought about by defining the M ₃₀ value of the insulating layer as 3.1 kg / mm ² or more. Therefore, when the insulated wire for a coil of the present invention is used, the defective rate of the manufactured coil can be significantly reduced, and the productivity of the coil can be improved.

Claims (1)

[Claims] 1. An insulated wire for a coil, comprising a conductor and an insulating layer covering the outer periphery of the conductor, wherein the insulating layer comprises a cross-linked product of an ethylene-fluoroolefin-based copolymer, and M of the cross-linked product. An insulated wire for a coil, which has a _30- value of 3.1 kg / mm ² or more.