JPH0610569Y2 - Foam insulated wire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a foam insulated wire used for a signal transmission cable or the like.

[Prior Art] A foam insulated wire used for a signal transmission cable of a computer, a high-speed information communication circuit, and the like has a delay time of 3.6 to 3.8 ns / m, which is close to that of space transmission due to a strong need for a smaller diameter and higher speed. , The degree of foaming of the insulator is also 7
The structure is such that most of it is 0 to 85% occupied by air.

For this reason, the foamed insulated wire has reduced mechanical properties such as compression, tension, and bending, and its strength is increased, so that an extremely thin skin layer having a thickness of several 10 μm is provided on the outer periphery of the foamed insulation.

In the meantime, foamed polyethylene or foamed fluorocarbon resin is used for the foamed insulation.In the case of conventional foamed polyethylene, only the polyethylene layer is used for the skin layer. It was

[Problems to be Solved by the Invention] When a polyethylene skin layer is provided on the foamed polyethylene insulator, the mechanical properties can be improved by conventional manufacturing techniques, but the skin layer thickness is limited to a minimum of 70 μm. Its permittivity was 1.31, which was an obstacle to lowering the permittivity.

On the other hand, when a fluororesin is used, not only electrical and mechanical properties but also heat resistance and other properties are excellent, and the workability of terminal processing such as soldering is improved, but compared to polyethylene, fluororesin is Very expensive and costly.

It is an object of the present invention to solve the problems of the prior art and to provide a foam insulated wire having relatively low cost and excellent mechanical properties such as compression characteristics and bending characteristics and excellent electrical characteristics such as dielectric constant. .

[Means for Solving the Problems] A feature of the present invention is that a foamed polyethylene insulator having a foaming degree of 70 to 85% is formed on the outer periphery of a conductor, and a thickness of 2 mm is formed on the outer periphery.
The point is that a skin layer of fluororesin having a thickness of 0 to 70 μm which can be melt-extruded is formed.

[Function] By forming an extremely thin skin layer of fluororesin extrudable on the outer periphery of a foamed polyethylene insulator having a foaming degree of 70 to 85%, relatively low cost and compression,
It is possible to realize a foam insulated wire having excellent mechanical properties such as bending and electrical properties such as dielectric constant.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of a foam insulated electric wire showing the present embodiment. In the figure, 1 is a conductor, 2 is a foamed polyethylene insulator having a foaming degree of 80% formed on the outer periphery of the conductor 1, and this embodiment is A skin layer 3 of fluororesin having a thickness of 20 to 70 μm and capable of being melt-extruded is formed on the outer side of the insulator 2.

As a fluororesin material, a tetrafluoroethylene-hexafluoropropylene copolymer (F
EP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) and the like are common, but when importance is attached to improvement of mechanical strength, ethylene-tetrafluoroethylene copolymer (ETFE), ethylene- Chlorotrifluoroethylene copolymer (ECTF
E), vinylidene fluoride polymer (PVdF) and the like are used.

FIG. 4 shows the relationship between the thickness of the skin layer 3 and the dielectric constant when the conventional polyethylene is used for the skin layer 3 (A) and when the fluororesin (PFA resin) of this embodiment is used (B). In the graph, the outer diameter of the insulator 2 is 0.85mm,
The size of the conductor 1 is 30 AwG (7 pieces / 0.102 mm, outer diameter: 0.306 mm). In the conventional example (A), the thickness of the skin layer 3 is limited to 70 μm, but in the present example (B), the thickness of the skin layer 3 can be set to a minimum of 20 μm, and the dielectric constant can be significantly reduced. it can.

FIG. 5 is a chart showing the difference in mechanical strength depending on the presence or absence of the skin layer 3. By providing the skin layer 3 of the PFA resin shown in this example, the compression characteristics and the bending characteristics are improved as compared with the case without the skin layer 3. In both cases, the strength increases 2-3 times or more.

2 and 3 are cross-sectional views of the cable when the foam insulated wire according to this embodiment is used as a coaxial cable and when it is used as a shield wire, and shows an application example of this embodiment. . 2 and 3, 4 is an outer conductor,
5 is a shield, 6 is a shacket, and 7 is a drain wire.

According to this example, by forming the skin layer of the fluororesin as described above, the mechanical strength of the foam insulated wire was improved at a relatively low price, and the deterioration of the low dielectric constant due to the skin layer was minimized. A signal transmission cable such as a coaxial cable can be provided.

[Advantage of the Invention] According to the present invention, a foamed insulated wire which solves the problems of the prior art and has excellent mechanical properties such as compression characteristics and bending characteristics and electrical characteristics such as dielectric constant at a relatively low cost is provided. Obtainable.

[Brief description of drawings]

FIG. 1 is a sectional view of a foam insulated wire showing an embodiment of the present invention, FIG. 2 is a sectional view of a coaxial cable using the foam insulated wire of FIG. 1, and FIG. 3 is a foam insulated wire of FIG. FIG. 4 is a cross-sectional view of a shielded wire using, and FIG. 4 is a graph showing the relationship between the thickness of the skin layer and the dielectric constant in the conventional example and one embodiment of the present invention,
FIG. 5 is an explanatory chart showing the difference in mechanical strength depending on the presence or absence of a skin layer according to an embodiment of the present invention. 1: conductor, 2: foamed polyethylene insulator, 3: skin layer, 4: outer conductor, 5: shield, 6: jacket, 7: drain wire.

Front page continued (72) Inventor Yasuo Sugimoto 5-1-1 Hidaka-cho, Hitachi-shi, Ibaraki Hitachi Cable Co., Ltd. Hidaka Plant (72) Masami Maeda 5-1-1 Hidaka-cho, Hitachi-shi, Ibaraki No. 1 in Hitachi Cable Co., Ltd. Hidaka Plant (56) Reference JP-A-63-21709 (JP, A) JP-A-63-21711 (JP, A) Actually opened Sho-57-12624 (JP, U) Actually opened SHO 61-19912 (JP, U) ACTUAL SHO 62-175611 (JP, U) ACTUAL HAI 2-73016 (JP, U) ACT KO 31-9755 (JP, Y1)

Claims (1)

[Scope of utility model registration request] 1. A foam insulated wire in which a foam polyethylene insulator having a foam degree of 70 to 85% is formed on the outer periphery of a conductor,
A thickness of 20 to 70 is provided on the outer circumference of the foamed polyethylene insulator.
A foam insulated electric wire, characterized in that a skin layer made of fluororesin having a thickness of μm and capable of being melt-extruded is formed.