JPH02174005A - Foam plastic insulated electric wire and manufacture thereof - 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 [Field of Industrial Application] The present invention relates to a novel foamed plastic insulated wire and a method for manufacturing the same.

[Prior Art] Conventional foamed plastic insulated wires are made by extrusion coating plastic containing a foaming agent on the outer periphery of a single body to form a foamed insulator.6 In recent years, with the aim of shortening propagation delay time, % or more of foamed plastic insulated wire has been studied, but if the highly foamed insulator is formed by extrusion coating, a space will be created between the conductor and the foamed insulator, resulting in extremely poor conductor adhesion. Become something.

In order to improve this conductor adhesion, it is generally known to have a solid layer or a low foam layer between the foam insulator and the conductor (Utility Model Publication No. 54-29487).

[Problems to be Solved by the Invention] As described above, in the case where the conductor adhesion is improved by interposing a solid layer or a low foam layer between the conductor and the foamed plastic insulator, the dielectric constant is increased around the conductor. Because there is a high layer,
It was not possible to obtain a core with short propagation delay time.

This invention was made in view of the above points, and eliminates the drawbacks of the above-mentioned conventional technology, has good conductor adhesion,
Moreover, it is an object of the present invention to provide a foamed plastic insulated wire having a core with an extremely low dielectric constant, and a method for manufacturing the same.

[Means and effects for solving the problem] The present invention has a configuration in which a conductor is surrounded by an intermediate layer made of conductive plastic or a composite of ordinary insulating plastic with a conductive filler to impart conductivity. As a result, the foamed plastic insulated wire has a low dielectric constant and extremely good conductor adhesion.

Further, a second invention of the present invention is such that a first extruder and a second extruder are connected to a crosshead, and a conductive filler is applied to the insulating plastic by the first extruder to a core wire passing through the center of the crosshead. This is a method for producing a foamed plastic insulated wire, in which a conductive material made of a composite material or a conductive plastic is extruded as an inner layer, and a foaming agent-containing plastic is simultaneously extruded and covered as an outer layer using the second extruder.

Therefore, a conductive intermediate layer can be simultaneously formed between the conductor and the foamed plastic insulator, and the adhesion of the conductor can be freely controlled. Further, it is possible to easily manufacture an electric wire with a short propagation delay time and good terminal processability.

[Example 1] Hereinafter, the present invention will be described in detail with reference to the drawings. The figure is a sectional view showing the main parts of the foamed plastic insulated wire manufacturing apparatus of the present invention. That is, the core MA3 is inserted into the central hole of the crosshead 4 consisting of nipples 5, 6 and die 7.
is formed so that it can be inserted and fed from right to left.

In the upper and lower right angle directions of this crosshead 4,
Conductive material made by mixing plastic with conductive filler,
Alternatively, a first extruder 1 for extruding conductive plastic and a second extruder 2 for extruding plastic containing one foaming agent are connected, respectively.

Therefore, when the conductor core wire 3 passes through the crosshead 4, the plastic containing the conductive filler or the conductive plastic from the extruder 1 is coated as an inner layer, and the outer periphery of the core wire 3 is simultaneously coated with the plastic containing the foaming agent as the outer layer. be done. The outer layer of plastic foams due to the pressure change when it is extruded outside through the die 7, and is then cooled to produce a foamed plastic insulated wire.

The insulating plastics used in this invention are compounded with conductive fillers to impart conductivity, such as polyethylene, vinyl, and fluororesin.

Sn is added to insulating plastic such as nylon or rubber.
, Cu, Ni, Al, Ag, or other metals, or carbon black or other conductive filler.

Conductive plastics include various plastics doped with electron donors or electron acceptors, such as trans-type polyacetylene, poly(vara-phenylene), polyacene, polypyrrole, polynaphthalene, graphite, and polynaphthalene doped. Use highly conductive plastics. this house,
Polynaphthalene exhibits high conductivity without doping and therefore can be used without doping. If necessary, a conductive filler may be mixed with these conductive plastics.

Next, a specific example will be described.

Medium-density polyethylene (density 0.945 g/cm", melt index 5 g/min) was used as the plastic inserted into extruder 2. This polyethylene was introduced into extruder 2 and melted at a temperature of 190 ° C. At the same time, from the injection part provided in the center of the cylinder of the extruder 2,
Freon 114 is continuously injected under pressure using a plunger-type metering pump, and is uniformly melted and mixed at a temperature of 200°C.
It was guided into crosshead 4. On the other hand, in the extruder 1, a conductive material made by mixing 80% by weight of a conductive filler with the same type of polyethylene as the polyethylene introduced into the extruder 1 is uniformly melt-kneaded at a temperature of 200°C. and introduced into the crosshead 4 from behind the nipple 5. The filler used here is an alloy whose main components are nickel and copper, and its breakdown is 66% nickel and 31.5% copper. These materials were combined at the exit of the die 7 and extruded. Immediately after being extruded, the polyethylene containing a foaming agent, which becomes the outer layer, starts foaming as shown by reference numeral 8. At the same time, the entire extruded polyethylene was drawn down to obtain the desired outer diameter.

The foamed plastic insulated wire obtained here has an outer diameter of φ0
．． 9mm, the degree of foaming of the foamed insulation was 80%6.
Since soldering was performed using the center conductor, the terminal workability was also very good.

[Effects of the Invention] As explained above, the foamed plastic insulated wire of the present invention can freely control conductor adhesion by providing a conductive intermediate layer between the conductor and the foamed insulator. Moreover, the propagation delay time is short, and the foamed plastic insulated wire has excellent terminal processability.

In addition, such a foamed plastic insulated wire is attached to the crosshead in the first place. It can be easily manufactured by joining a second extruder and performing coextrusion coating.

[Brief explanation of the drawing]

The figure is a sectional view of an extrusion device showing the main parts of the foamed plastic insulated wire manufacturing device of the present invention. 1... 2 3... 4... 5.6 7... First extruder Second extruder Conductor core cross head Nipple die Patent applicant Hitachi Cable, Ltd.

Claims (2)

[Claims] (1) In a foamed plastic insulated wire in which the outer periphery of the conductor is coated with foamed plastic as an insulator, a conductive layer is formed between the conductor and the foamed plastic insulator by combining a conductive filler with ordinary insulating plastic to impart conductivity. , or a foamed plastic insulated wire characterized by forming a conductive plastic layer. (2) A first extruder that extrudes a conductive material made of a composite of insulating plastic with a conductive filler or conductive plastic as an intermediate layer around the outer circumference of the conductor, and a second extruder that extrudes foamed plastic as an insulating layer. A method for manufacturing a foamed plastic insulated wire, characterized in that a core conductor passing through the crosshead is coated with an intermediate layer of conductive plastic and a foamed insulator by extrusion at the same time.