JP2000260235A - Flexible cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lightweight and outgas free cable excellent in environment resistant characteristics such as heat resistance, cold resistance, flame resistance and chemical resistance and excellent in flexibility by forming a foamed fluorinated resin layer as a sheath on the circumference of a cable provided with at least one insulated wire formed by covering the periphery of a conductor with an insulation. SOLUTION: This flexible cable 10 is provided with insulated wires 16 each formed by covering the periphery of a conductor 12 with an FEP (tetrafluoroethylene-hexafluoropropylene copolymer) as an insulation 14. Around the insulated wires 16, a foamed fluorinated resin layer 18 of an FEP is formed as a sheath. the foaming rate of the foamed fluorinated resin layer 18 is set to, preferably 30-70% and most preferably 50-60%. By using such a foam fluorine resin layer 18 as a sheath, the cable can be reduced in weight even if the sheath of the fluorinated resin is used, and sufficient flexibility can be provided for it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible cable which is lightweight, excellent in environmental resistance and highly flexible.

[0002]

2. Description of the Related Art Conventionally, a sheath is provided on the outer periphery of a cable to protect the cable from external force or corrosion. For such a sheath, for example, various plastic materials are used, and in consideration of heat resistance, nonflammability, chemical resistance, and the like, the use of a fluororesin is preferable, but a conventional fluororesin is used for the sheath. In this case, there is a problem that the flexibility is poor and the weight of the cable increases. In addition, when vinyl chloride, which has good flexibility and can be made relatively small in weight, is used for the sheath, heat resistance, cold resistance, chemical resistance, and the like are poor, and the flexibility is contributed. It is difficult to use it in the electronics industry, for example, for wiring of equipment involved in the production of semiconductors that require a clean environment, because the plasticizer added to the CNT may contaminate the surrounding atmosphere as outgas. Furthermore, it is also difficult to use it for indoor wiring requiring nonflammability. As a material for compensating some of the above-mentioned problems or difficulties, there is a sheath using fluororubber, but it is insufficient in cold resistance and outgassing.

[0003]

SUMMARY OF THE INVENTION The present invention relates to a flexible cable which is excellent in environmental resistance characteristics such as heat resistance, cold resistance, nonflammability, chemical resistance and the like, and is lightweight, outgas-free and excellent in flexibility. To provide.

[0004]

The above objects are achieved by the flexible cable of the present invention. That is, in summary, the present invention provides a cable including at least one insulated wire in which an insulator is coated around a conductor, wherein a foamed fluororesin layer is provided as a sheath around the outer periphery of the cable. It is a flexible cable.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to specific embodiments. Referring to FIG. 1, there is shown an embodiment of a flexible cable 10 according to the present invention,
The flexible cable 10 has an insulator 1 around a conductor 12.
As No. 4, at least one or more insulated wires 16 coated with FEP (tetrafluoroethylene-hexafluoropropylene copolymer) are provided (in the embodiment shown in FIG. 1, eight insulated wires 16 are twisted. There). Around the insulated wire 16, an FEP foamed fluororesin layer is provided as a sheath 18. This foamed fluororesin layer 1
8 has a foaming ratio of preferably 30 to 70%, more preferably 40 to 60%, and most preferably 50 to 60%. By using the foamed fluororesin layer as the sheath as described above, it is possible to reduce the weight while being a fluororesin sheath, and to obtain sufficient flexibility. When the foaming ratio is 30% or less, the weight and flexibility are insufficient, and when the foaming ratio is 70% or more, the mechanical strength is reduced and the material is unsuitable as a sheath material.

Further, by setting the thickness of the foamed fluororesin layer 18 to 50% to 100% of the entire thickness of the sheath, the flexibility and the mechanical strength can be adjusted in the same manner as described above. In this case, that is, when the foamed fluororesin layer 18 is formed in a range of 50 to 100% of the entire thickness of the sheath, after the foamed fluororesin layer 18 is formed, a solid fluororesin layer is coated on the periphery thereof. Alternatively, the order of coating may be changed to form a solid fluororesin, and then a foamed fluororesin layer 18 may be coated on the periphery thereof. It is also possible to provide it at a site.

The insulator 14 and the foamed fluororesin layer 18 are made of a tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (PF).
A), heat-fusible fluororesins such as tetrafluoroethylene-hexafluoropropylene copolymer (FEP) and ethylene-tetrafluoroethylene (ETFE).

[0008]

Next, the present invention will be described with reference to examples. Example 1 FEP was applied to the outer periphery of a soft copper wire having an outer diameter of 0.5 mm to a thickness of 0.2 mm.
, Two twisted insulated wires were coated to form a pair, and these were further combined into four pairs and twisted to form a cable core.

FEP pellets in which 0.2 to 0.5% by weight of boron nitride was mixed and dispersed as a foaming nucleating agent were put into a hopper of an extruder for covering an electric wire sheath, and were melt-kneaded. From about 0.4 to about 0.4 mm from the middle of the extruder cylinder.
Nitrogen gas was injected into the molten FEP at a pressure of 5 MPa, which was foamed. FE foamed in this way
P was extruded and coated around the cable core. The thickness of the sheath made of the foamed FEP of the above cable is 0.4 m.
m, its foaming ratio was 50%, and it had sufficient flexibility.

EXAMPLE 2 Four insulated wires, each of which is made of seventeen tinned soft copper wires having an outer diameter of 0.127 mm and twisted and coated with a 0.2 mm thick FEP on the outer periphery of the conductor, are collectively twisted together with 54 wires. Outer diameter of 0.1
A copper core was prepared by horizontally winding a tin-plated annealed copper wire having a thickness of 2 mm.

Around the above cable core, a foamed FEP was coated in the same manner as in Example 1. The thickness of the sheath made of foamed FEP of the cable thus completed is 0.8.
mm, and its foaming ratio was 50%. Foamed FEP
The cable in which the horizontal shield was provided inside the sheath also had sufficient flexibility as in Example 1.

Next, the following test was conducted to compare the flexibility of the flexible cable according to the present invention with that of the conventional flexible cable. First, as Comparative Example 1, soft vinyl chloride was extrusion-coated around the same cable core as in Example 1,
A cable having a soft vinyl chloride sheath having a thickness of 0.4 mm was prepared. Next, as Comparative Example 2, a solid FEP was extruded around the same cable core as in Example 1 to cover it, and a cable having a 0.4 mm thick solid FEP sheath was prepared.

Each cable of Example 1, Comparative Example 1 and Comparative Example 2 was cut to a length of 200 mm, and the cable cut to 200 mm was attached to a flat plate 20 vertically to the ground as shown in FIG. . At this time, the upper half 100 mm portion of the cable is fixed to the flat plate 20 and the lower half 10 mm.
The 0 mm portion was left free without being fixed. Next, the lower half of this cable, 100 mm, was bent until it became horizontal with respect to the ground.
Was placed on a sample table, and its load was measured. The load value at this time was as shown in Table 1. As can be seen from Table 1, Example 1 in which the foamed FEP according to the present invention was used as the sheath had a smaller load value in bending than Comparative Example 2 in which the solid FEP was used as the sheath, and Comparative Example 1 in which soft vinyl chloride was used as the sheath. It showed a value close to the load value. From this, it is understood that a cable having a foamed FEP as a sheath has more flexibility than a cable having a solid FEP as a sheath.

[0014]

[Table 1]

Further, when a force is applied to the surface sheaths of the cables of Examples 1 and 2 to deform them, there is a tendency that the deformed state is relatively maintained. This is similar to plastic deformation unlike elastic deformation of general rubber,
This is considered to be a unique property observed when a thermoplastic resin such as a fluororesin is foamed. As a result, the flexible cable according to the present invention has low rebound resilience, is easily bent and deformed, and has a characteristic not easily provided in other rubber sheathed cables that it is relatively easy to keep the deformed state.
It is also excellent in workability.

In the present invention, the sheath provided with the foamed fluororesin layer may be not only the outermost layer of the cable as in the above embodiment but also an inner sheath, and the inner and outer layers of the sheath may correspond to the case. It may be a braid or a tape wound with metal or the like. The shape of the cable is not limited to a circular shape, but may be a flat shape in which core wires are arranged in parallel. Modifications within the technical concept of the present invention are of course possible.

[0017]

As described above, according to the flexible cable of the present invention, since the foamed fluororesin layer is provided on the sheath of the cable, the flexible cable has excellent environmental resistance characteristics inherent to the fluororesin. In addition, it has the effect of having light weight and excellent flexibility. Furthermore, since the sheath made by foaming a fluororesin, which is a thermoplastic resin, like the flexible cable of the present invention is not elastic as fluororubber and is easily deformed plastically, pressure is applied to the cable surface. In addition to the above, there is an advantage that the outer diameter of the cable can be easily reduced, and even if the cable is bent to deform the shape, the shape tends to be relatively maintained, and the construction is easy. Excellent outgassing properties

[0018]

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of a cable according to the present invention having a foamed fluororesin sheath around a cable core.

FIG. 2 is a diagram showing a method for measuring the flexibility of a cable.

[Description of Signs] 10 ... Flexible cable 12 ... Conductor 14 ... Insulator 16 ... Insulated wire 18 ... Sheath 20 ... Plate 22 ... Electronic balance

Claims (4)

[Claims] 1. A flexible cable comprising at least one insulated wire in which an insulator is covered around a conductor, wherein a flexible fluororesin layer is provided as a sheath on the outer periphery of the cable. 2. The foamed fluororesin layer has a foaming rate of 30 to 30.
The cable according to claim 1, wherein the cable is 70%. 3. The cable according to claim 1, wherein the thickness occupied by the foamed fluororesin layer is 50 to 100% of the entire thickness of the sheath. 4. The material of the foamed fluororesin layer is selected from the group consisting of a tetrafluoroethylene-perfluoroalkylvinyl ether copolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and an ethylene-tetrafluoroethylene copolymer. The cable according to any one of claims 1 to 3, characterized in that: