JPS6014713A - Method of producing high pressure insulated 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 of the Invention] The present invention relates to a method for manufacturing a high voltage insulated wire with improved thermal deformability and the like.

[Background of the invention]

In recent years, with the spread of televisions, microcomputers, etc., there has been a remarkable increase in demand for high voltage insulated wires as lead wires for high voltage transformers of cathode ray tubes in the image display units of these devices. The performance of this high-voltage insulated wire is regulated by various standards from the standpoint of disaster prevention and reliability, and in particular UL (Underwrite).
rs Lab, ) standard is a representative one.6 In that standard, in order to satisfy flame retardancy and voltage resistance,
Until now, we have adopted a two-layer structure using polyethylene as the insulating layer and plasticized vinyl chloride resin as the outer coating. In order to pass all of the standards such as flame retardancy, heat deformability, and cut-through resistance, the plasticized vinyl chloride resin composition for the outer coating layer must have a formulation that is extremely difficult to process. The reality was that they were not able to obtain the desired results.

The most severe test item for high voltage insulated wires is the high voltage power through test. This test is carried out using the method shown in Figure 1, in which a voltage of 1.5 times the rated voltage is applied in an atmosphere at the operating temperature to ensure that the product does not break down for more than 7 hours. 1st
In the figure, (1) is a drill rod with a diameter of 1/32 inch, (
2) is an insulated wire sample hung on the drill rod (1), (
3) and (3') are loads of 2 bonds each, (4) is the lead wire to the high voltage power supply, and (5) is the ground. This test is extremely strict, requiring both heat deformation resistance and voltage resistance.

A double-structured high-voltage insulated wire using a resin composition with good moldability as the outer coating layer was subjected to a combustion test (vertical combustion test) and a high voltage force through test, but failed. The reason for the failure was that the fluidity at high temperatures improved.
This is thought to be due to dripping of the outer coating layer in the combustion test, and etch cutting into the outer coating layer in the cut-through test.

Therefore, as a method to improve these drawbacks, we investigated a method of improving fluidity at high temperatures by crosslinking the resin. As a crosslinking method, irradiation crosslinking was performed using an electron beam accelerator. As a result, it was found that the combustion test passed without any dripping.

On the other hand, in the cut-through test, although the etch penetration into the outer coating was reduced, it was destroyed within 1 hour after charging.
I still failed.

[Summary of the Invention] The present invention provides a method for manufacturing a high voltage insulated wire that passes the above-mentioned combustion test and high voltage power through test. A method for producing a high-voltage insulated wire is characterized in that after molding, the outer coating layer is irradiated and crosslinked using an accelerating voltage such that the maximum reachable distance of the accelerated charged particles is smaller than the thickness of the outer coating layer.

[Detailed description of the invention]

In the present invention, as the accelerated charged particles, an electron beam is preferable, and the acceleration voltage and the maximum reachable distance of the accelerated charged particles (density 1
Figure 2 shows the relationship in the case of the following substances. The maximum reachable distance of the accelerated charged particles to the outer coating layer according to the present invention can be determined by the following equation.

D = Do/ρ D: Maximum reach distance of accelerated charged particles in the outer coating layer Do: Maximum reach distance of accelerated charged particles in a substance with density 1 ρ: Density of the resin composition of the outer cover layer Select an accelerating voltage that is smaller than the thickness of the coating layer, and only the outer coating layer is irradiated and crosslinked.

Furthermore, in order to uniformly crosslink the outer coating layer by irradiation, it is also possible to employ a reversal method using a magnetic field disclosed in Japanese Patent Publication No. 51-23679.

The present invention will be explained below using specific examples.

A tin-plated conductor of Example AWC22 was extruded coated with an insulation thickness of 0.76sxO high-density polyethylene, and then a composition (density 1.4) mainly composed of vinyl chloride-ethylene vinyl acetate graft polymer was coated as an outer coating layer with a thickness of 0.76sxO high-density polyethylene. Extrusion coated with a thickness of 0.95 mm. Next, an electron beam was emitted for 10 minutes using an electron beam accelerator with an accelerating voltage of 300 KeV (maximum reach distance of 0.9 M in a material with a density of 1).
Mrad irradiation was carried out to produce an insulated wire with a DC4 rating. Using this electric wire, a vertical combustion test specified by UL758 and the above-mentioned high voltage power test were conducted.

Comparative Example A high-voltage insulated wire with an extrusion coated outer coating layer in the same manner as in the example was used as an electron beam in an electron beam accelerator with an accelerating voltage of 2 MeV (maximum reach distance of 9 nautical miles in a material with a density of 1). It was irradiated with 10 Mrad to produce an insulated wire with a rating of DC401ff. The electric wire was also subjected to a vertical combustion test and a high pressure through test in the same manner as in the examples. Similar tests were also conducted on non-irradiated wires. The test results are shown in Table 1. The non-irradiated electric wire of the comparative example failed both the combustion test and the cut-through test, and the irradiated electric wire passed the combustion test but failed the cut-through test.

Table 1 Test results *O Pass × Fail

[Brief explanation of the drawing]

Figure 1 shows the high pressure through test method, (1) is the drill rod, (2) is the high voltage wire sample, (3) is the load (<8'), and (4) is the lead wire to the high voltage power supply. , (5) indicates grounding. FIG. 2 is a graph showing the relationship between accelerating voltage and the maximum travel distance of charged particles in a material with a density of l. Agent Patent Attorney Tetsuji Kamiyo

Claims (1)

[Claims] (1) After extruding an outer coating layer on the outside of the insulating layer, the outer coating layer is irradiated and crosslinked using an accelerating voltage such that the maximum reachable distance of accelerated charged particles is smaller than the thickness of the outer coating layer. A method for manufacturing high voltage insulated wires.