JPH06290644A - Foaming insulating wire - Google Patents

Abstract

PURPOSE:To improve the anti-collapse property as well as to improve the appearance, and to improve the extension and the mechanical strength of an insulator. CONSTITUTION:A foaming insulator 2 formed of a polymer to which thermal expansion hollow balls are added is provided to the outer periphery of a conductor 1, and a foam skin layer 3 which consists of a nonfoaming plastics is provided to the outer periphery of the foaming insulator 2. The Shore hardness of the foam skin layer 3 is made 60 or higher, and its thickness is made 2 to 40% of the thickness of the foaming insulator 2. The material to form the foam skin layer 3 is a material selected from a high density polyethylene, polypropylene, polymethylpenten-1, polyimide (nylon), and polyester.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foam insulated wire,
In particular, it relates to a foam insulated electric wire of this type foamed by a thermally expandable hollow sphere.

[0002]

2. Description of the Related Art With the rapid increase in speed of computers,
Wires and cables with high-speed transmission and low attenuation are used. Foam-insulated electric wires are used as electric wires and cables to meet the demand. In particular, as the foamed insulator, a composition obtained by adding thermally expandable hollow spheres to a polymer is extruded and coated on a conductor by an extruder to have a high porosity and a low dielectric constant.

[0003]

A foamed insulated wire made of a conventional composition containing a heat-expandable hollow sphere has a poor appearance due to uneven expansion of the hollow sphere and is easily crushed due to high foaming. Further, the compatibility of the polymer and the heat-expandable hollow sphere is poor, and there is a problem that the insulator does not expand.

The present invention breaks the state of the art of the prior art described above, improves the appearance, improves the crush resistance, and improves the elongation of the insulator and the mechanical strength. The purpose is to provide electric wires.

[0005]

The foam insulated wire provided by the present invention is one in which a foam insulation is provided on the outer periphery of a conductor and a foam skin layer made of non-foamed plastic is provided on the outer periphery thereof. The foam skin layer has a Shower hardness D of 60 or more and a thickness of 2 to 40% of that of the foamed insulation.

The foam skin layer is preferably made of a hard material, and has a Shore D hardness of 60 or more. The thickness of the foam skin layer is 2 to 4
The reason for setting 0% is as follows. That is, if it is less than 2%, the foamed state of the hollow spheres of the internal foamed insulator appears on the surface of the skin layer and the appearance is deteriorated, and the elongation of the insulator is 20%.
This is because it will be less than%. On the other hand, if it exceeds 40%, the relative permittivity is remarkably increased and the meaning as a highly foamed insulated electric wire is lost.

Materials for the foam skin layer include high density polyethylene, polypropylene, polymethylpentene-
1, polyimide (nylon), polyester may be selected.

The foamed insulator is a polymer foamed by containing thermally expandable hollow spheres.

[0009]

FIG. 1 shows an embodiment of the foam insulated wire of the present invention in a cross-sectional structure, in which 1 is a conductor, 2 is a foam insulator, and 3 is a foam skin layer.

The conductor 1 is preferably a stranded wire so as not to impair the flexibility of the electric wire. The foam insulation 2 is
A composition obtained by adding heat-expandable hollow spheres to a polymer is extrusion-coated on a conductor by an extruder. The foam skin layer 3 is a non-foamed plastic selected from high-density polyethylene, polypropylene, polymethylpentene-1, polyimide (nylon), and polyester, and is foamed by an extruder 2
It is to be extrusion coated on top.

[Example 1] Seven copper wires having an outer diameter of 0.127 mm were twisted to form a conductor composed of a stranded wire having an outer diameter of 0.38 mm (28 AWG), and an ethylene-vinyl acetate copolymer, low density was used. A compound comprising polyethylene and heat-expandable hollow spheres is supplied to an extruder to be extruded and coated on a conductor to form a foamed insulator, and then high density polyethylene (MI = 0.
8. Density = 0.95), and this is extruded and coated on the foamed insulation by an extruder so that the ratio to the foamed insulation is 5% and the thickness is 30 μm, and the outer diameter is 1.5 mm. It was manufactured so that Here, the thermally expandable hollow spheres used had a shell composition of methyl methacrylate acrylonitrile, an encapsulating agent of isobutane, a softening and foaming initiation temperature of 100 ° C., and a particle diameter of 32 to 62 μm.

The foamed insulated electric wire obtained as described above had a foaming degree of 71% and a good appearance. The rate of deformation of this insulated wire when a load of 500 g was applied at a temperature of 50 ° C. was 5%, and the deformation 5 minutes after the load was removed was 2%. The elongation was 210% when the pulling speed was 200 mm / min, and the elongation condition of 100% or more in the UL standard could be sufficiently satisfied.

[Comparative Example 1] Seven copper wires having an outer diameter of 0.127 mm were twisted to form a stranded wire having an outer diameter of 0.38 mm (28 AWG) on an ethylene-vinyl acetate copolymer, low density. A compound comprising polyethylene and heat-expandable hollow spheres was supplied to an extruder and extrusion-coated on a conductor to form a foamed insulation, and then the same high-density polyethylene as in Example 1 was used as a foam skin layer to form an insulation. An electric wire having an outer diameter of 1.5 mm was produced by setting the thickness ratio to 1%.

According to this foam insulated wire, the appearance was not good, and the deformation rate was 12% when a load of 500 g was applied at a temperature of 50 ° C. Further, the elongation was 12% when the pulling speed was 200 mm / min, which was a problem in practical use.

[Comparative Example 2] Seven copper wires having an outer diameter of 0.127 mm were twisted, and a conductor composed of a stranded wire having an outer diameter of 0.38 mm (28 AWG) was used. A compound comprising polyethylene and heat-expandable hollow spheres was supplied to an extruder and extrusion-coated on a conductor to form a foamed insulation, and then the same high-density polyethylene as in Example 1 was used as a foam skin layer to form an insulation. An electric wire having an outer diameter of 1.5 mm was manufactured by setting the thickness ratio to 50%.

In this foam insulated wire, the foaming degree of the foamed insulator was 70%, but the permittivity was 1.55, and the production was stopped because the permittivity was too high as a product.

[0017]

According to the foam insulated wire of the present invention as described above, the foam skin layer of the non-foamed plastic is provided on the outer periphery of the foam insulation provided on the conductor, and the Show hardness D of this foam skin layer is set. Since it is 60 or more and the thickness of the same layer is 2 to 40% of that of the foamed insulator, the appearance is improved and the crush resistance is improved,
The intended purpose of providing this type of foam insulated wire that can improve the elongation of the insulator and the mechanical strength is sufficiently achieved, and the practical effect is great.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a foam insulated wire according to the present invention.

[Explanation of symbols]

 1 conductor 2 foam insulation 3 foam skin layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takayasu Asai 5-1-1 Hidaka-cho, Hitachi-shi, Ibaraki Hitachi Cable Co., Ltd. Hidaka factory (72) Inventor Masao Shirato 5 Hidaka-cho, Hitachi-shi, Ibaraki 1-1-1 Hitachi Cable Co., Ltd. Hidaka Factory

Claims (3)

[Claims] Claims: 1. A foamed insulator is provided on the outer circumference of a conductor, and a foam skin layer made of non-foamed plastic is provided on the outer circumference thereof, and the foam skin layer has a Shower hardness D.
To 60% or more and the thickness thereof is set to 2 to 40% of that of the foamed insulating body. 2. The foam insulated wire according to claim 1, wherein the material forming the foam skin layer is selected from high density polyethylene, polypropylene, polymethylpentene-1, polyimide (nylon), and polyester. 3. The foamed insulated wire according to claim 1, wherein the foamed insulation is foamed by containing hollow particles having thermal expansion properties in a polymer.