JPS61203507A - Thin covered 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 thin coated electric wire suitable for wiring in a limited space such as an automobile, a vehicle, or various electronic devices.

[Prior art and its problems]

Recently, there has been a strong demand for space saving and weight reduction of coated electric wires used in automobiles, vehicles, various electronic devices, etc., and therefore, it is being considered to reduce the coating thickness. Conventional electric wires of this type have four twisted wires, but the coating thickness is 0.4
The thickness is approximately 1.1 .mu.m, and if the coating thickness is made thinner than this, the mechanical strength of the wire, such as the abrasion resistance, decreases, so there is a limit to how thin the wire can be made.

Measures for solving problem C and their effects] As a result of various studies to solve the above-mentioned problems of the conventional technology, we found that a specific thermoplastic polyurethane resin was used as the coating material to reduce the coating thickness. , gained the knowledge that the wear resistance changes greatly depending on the degree of fall of the resin into the valley between the wires inside the circumscribed circle of the P8 wire conductor,
This has led to the completion of the present invention.

That is, the thin-walled electric wire of the present invention is made by coating a stranded conductor with a thermoplastic polyurethane resin having a Shore D hardness of 60 or more at a temperature of 25°C, and the resin thickness outside the circumscribed circle of the stranded conductor is The diameter is 50 to 250 μm, and the amount of the resin falling into the valley between the strands inside the circumscribed circle is 20% or more of the maximum value.

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The valleys between the strands on the inside of the tangent circle are completely filled with resin.

゛ Thermoplastic polyurethane resin is made by combining a long chain polyol with polyester or polyether bonds and a short chain polyol with an aromatic or aliphatic diisocyanate.
- urethane bond (-NHCO
O-) have thermoplasticity due to their almost linear arrangement,
It can be melted and shaped at high temperatures. Polyols and diisocyanates having various hardnesses can be obtained depending on the selection of polyols and diisocyanates, but in the present invention, polyols and diisocyanates having a Shore D hardness of 60 or more at a temperature of 25° C. are used. If the hardness is less than 60, it will be too soft and it will not be possible to obtain an electric wire with a thin coating and excellent mechanical properties as intended by the present invention.

The resin thickness outside the circumscribed circle of the stranded conductor is 50 to 250 μm.
The reason for this is that in order to save space and reduce weight, which is the objective of the present invention, it is desirable that the coating thickness be as thin as possible.
If it exceeds 250 μm, the degree of improvement in wear resistance due to the above-mentioned drop will be small, and wear resistance will hardly change even if the drop is increased, and if it is less than 50 μm, a uniform coating will not be obtained and it cannot be used as a coated wire. , etc.

The thickness of the resin outside the circumscribed circle of the flammable conductor is more preferably 100 to 200 μm.

〔Example〕

FIG. 1 shows an embodiment of the invention. This thin-walled electrical wire is made by extruding a thermoplastic polyurethane resin coating 3 having a Shore D hardness of 60 or more at a temperature of 25°C on the outer periphery of a stranded conductor 2 made by twisting seven copper wires 1 together. in,
The thickness of the resin coating 3 outside the circumscribed circle (indicated by a broken line) of the stranded conductor 2 is 50 to 250 μm. Further, the resin coating 3 is formed so that a depression 5 is formed in the valley 4 between the adjacent strands 1 inside the circumscribed circle,
The size of the depression 5, that is, the depression, is 20% or more, assuming that the state A in which the valleys 4 between the strands 1 are completely filled, as shown by the dots in Fig. 2, is the maximum (100%). ing.

Next, we will explain the test results of the prototype. In the electric wire shown in Fig. 1, the outer diameter of the copper wire l is 0.32 m+, the Shore D hardness of the thermoplastic polyurethane resin coating 3 is 74, and the thickness of the resin coating 3 outside the circumscribed circle of the stranded wire conductor 2. If is 150pm,
When the above-mentioned drop is changed, the wear resistance becomes as shown in Table 1.

Table 1 Abrasion resistance: A hard chrome-plated steel blade with a 0.125H edge was tested on a wire under a load of 1.
．． When the thermoplastic polyurethane resin is reciprocated at a rate of 35 kg, a stroke of 10 m, and a reciprocating rate of 60 reciprocations/min, the wear resistance is significantly improved if the drop is 20% or more as described above.

The downside is P! It is known that when coating a wire conductor with resin by extrusion, it changes depending on the die-nimple structure, melt viscosity of the resin, extrusion pressure, temperature of the stranded wire conductor, wire speed, etc. For example, Example 1 The extrusion conditions are as follows.

Nipple diameter 1.00 Tsuru Gui diameter 1.26 Tsuru resin melt viscosity 30,000 poise at 220°C Extrusion pressure 50kg/I++m” Temperature of stranded conductor Room temperature (23°C) Line speed 100m/min Next, outer diameter 0 A stranded conductor made by twisting 26M copper wires in an array of 1, 6, or 12 wires and coated with thermoplastic polyurethane resin with a Shore D hardness of 74. Table 2 shows the test results when the coating thickness was varied.

Also, for the same stranded conductor, there is a part Tl outside its circumscribed circle.
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Table 3 shows the test results when the Shore D hardness was varied using HAl coated electric wires.

Table 2 Table 3 [Effects of the Invention] As explained above, the thin coated electric wire of the present invention has a thin coating thickness and excellent wear resistance, and reduces the wiring space.
This greatly contributes to reducing the weight of wiring.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a thin-walled electric wire according to an embodiment of the present invention, and FIG. 2 is an enlarged view of a main part of the same electric wire. 1 - Copper strands, 2 - Twisted wire body, 3 - Thermoplastic polyurethane resin coating, 4 - Valley between strands, 5 - Depression. Figure 1

Claims (1)

[Claims] A stranded conductor is coated with a thermoplastic polyurethane resin having a Shore D hardness of 60 or more at a temperature of 25°C, and the resin thickness outside the circumscribed circle of the stranded conductor is 50 to 250 μm, and the circumscribed circle is A thin-walled electrical wire, characterized in that the amount of the resin falling into the valleys between the strands on the inner side is 20% or more of the maximum value.