JPH05159636A - Rubber insulated electric wire and manufacture thereof - Google Patents

Abstract

PURPOSE:To improve the quality and reduce the cost in the manufacture of insulated electric wire. CONSTITUTION:As a semiconductive layer 3, the polymer, which is mainly composed of polyolefine or the like, is used. The surface of the semi-conductive layer 3 is solidified by cooling to increase the mechanical strength thereof, and two extruders 11, 12 are arranged in series to adopt a method for extruding two layers of the semiconductive layer 3 and an insulator 5 continuously. A silicone group adhesive layer 4 such as primer or the like is provided by vulcanization to eliminate the generation of a clearance between the semiconductive layer 3 and the insulator 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber-insulated electric wire and a method for manufacturing the same, and more specifically, it is used as a high voltage lead wire for mercury lamps and discharge lamps used for illumination of facilities such as roads and gyms, In particular, it is possible to continuously manufacture a product in which a plastic semiconductive layer is interposed between a conductor and a rubber-based insulator.

[0002]

2. Description of the Related Art Conventionally, as a lead wire for a high voltage or a lead wire for a high voltage motor as described above, a conductor such as a stranded copper wire, a plastic material such as polyethylene or Teflon, or E
Insulated wires in which a rubber-based insulator such as PDM or silicone rubber is directly coated are often used. Since the insulated wire has a structure in which the conductor is directly covered with the insulator, air bubbles or voids are easily generated between the conductor and the insulator, and when a high voltage is applied, corona discharge is generated at that portion and insulation is performed. There is a problem that the body is eroded and dielectric breakdown occurs.

As a solution to this problem, a semiconductive layer having a chemical affinity with the insulator is provided between the conductor and the insulator, and the semiconductive layer and the insulator are brought into close contact with each other to eliminate bubbles and the like. ,
Therefore, a method of improving the withstand voltage characteristic is adopted. As a material for the semiconductive layer, a polymer having a chemical structure identical to or similar to that of an insulator and a conductivity-imparting agent such as carbon black or graphite is generally used.

When the insulator is a plastic such as polyethylene, a semiconductive material obtained by mixing polyethylene with carbon black is used. When the insulator and the semiconductive layer are both plastics, the two extruders are connected in series by utilizing the property that the plastics are extruded in a heated / melted state and then solidified by cooling. A method of arranging and conducting two-layer extrusion of the semiconductive layer and the insulator continuously can be adopted.

[0005]

However, when the insulator and the semiconductive layer are rubber-based such as silicone rubber and EPDE, they are extruded and then immediately vulcanized by heating or the like,
It is necessary to make the rubber molecules into a mesh structure. This is because the unvulcanized rubber that has just been extruded exhibits a clay-like property in which it is plastically deformed by an external force or the like, and unlike a plastic system, it does not solidify only by cooling and the mechanical strength does not increase.

Therefore, when manufacturing an insulated wire in which the insulator and the semiconductive layer are rubber-based, the semiconductive layer is extruded and molded by the first extruder, and then immediately vulcanized to once form a drum or the like. There is no choice but to employ a method in which, after the winding and vulcanization are completed, the insulator is extruded and coated by the second extruder, and then immediately vulcanized. Therefore, like the method of manufacturing an insulated wire in which the insulator and the semiconductive layer are plastic, two extruders are arranged in series to continuously perform the two-layer extrusion of the semiconductive layer and the insulator. However, there is a problem in that the quality is lowered and the cost is increased.

The present invention has been made in view of the above problems, and provides a rubber insulated wire having a structure that can be continuously manufactured, and a method for manufacturing the rubber insulated wire, which improves the quality of the rubber insulated wire and reduces the cost. The purpose is to

[0008]

In order to achieve the above object, the present invention is directed to coating a conductor with a plastic semi-conductive layer obtained by adding carbon black, graphite or the like to a polymer, A rubber-insulated electric wire having a surface covered with a rubber insulator via a rubber-based adhesive layer.

Silicon rubber is preferably used as the rubber of the above-mentioned insulator, and silicone rubber adhesive such as a primer is preferably used as the rubber adhesive. For the semiconductive layer, a polymer containing a polyolefin as a main component and a conductivity-imparting agent such as carbon black or graphite added thereto is preferably used. For example, a mixture of polyethylene and ethylene propylene rubber to which acetylene black, graphite or the like is added and which has a specific resistance of 10 ³ to 10 ⁶ ohm · cm is also suitably used.

The present invention provides a method for continuously producing the above-described rubber insulated wire, in which two extruders are arranged in series and continuously,
Extruded by a first extruder so as to cover the surface of the conductor with a semiconductive layer of a polymer to which carbon black, graphite, etc. are added, and then, after cooling, a rubber-based insulator is extruded by a second extruder. The present invention provides a manufacturing method in which extrusion, coating, and immediate vulcanization are performed.

Further, the semiconductive layer is extruded by the first extruder and cooled, and then a rubber adhesive is applied to the surface of the semiconductive layer, and then a rubber insulator is extruded by the second extruder. You may do it.

Furthermore, the present invention provides a continuous manufacturing method in which two extruders are arranged in series to continuously
Extruder is used to extrude a polymer semi-conductive layer containing carbon black, graphite, etc. so as to cover the conductor surface, and then a second extruder is used to extrude a rubber-based insulator to cover the semi-conductive layer. Then, after that, the semiconductive layer and the insulator may be brought into close contact with each other by decomposing the crosslinking agent of the semiconductive layer and the insulator through a steam vulcanization tube and simultaneously crosslinking.

As described above, when the semiconductive layer and the cross-linking agent for the insulator are cross-linked and adhered to each other, the same cross-linking agent such as dicumyl peroxide, 2.5 dimethyl 2.5 di (tert. It is preferable to add butylperoxy) hexane etc. to the semiconductive layer and the insulator. When vulcanizing with a warm air vulcanizer without using a steam vulcanizing tube, apply a rubber-based adhesive between the semiconductive layer and the insulator as in the manufacturing method described above. It is preferable to set.

[0014]

According to the present invention, since the semiconductive layer is mainly made of a polymer such as polyolefin, the semiconductive layer is extruded by the first extruder and then cooled. Solidify, increasing the mechanical strength. This eliminates the need for conventional vulcanization, so that it is possible to employ a method in which two extruders are arranged in series and two-layer extrusion of the semiconductive layer and the insulator is continuously performed. The cost of electric wires can be reduced. In addition, since the mechanical strength is increased, the quality is stable because it is not damaged even if it comes into contact with the coating device of the second extruder.

Furthermore, although the plastic semiconductive layer and the rubber insulator have a low affinity, a gap is formed between the semiconductive layer and the insulator by interposing a silicone adhesive layer such as a primer. Since it does not occur, the withstand voltage characteristic is improved.

[0016]

The present invention will be described in detail below with reference to the embodiments shown in the drawings. As shown in FIGS. 1 to 3, in the manufacturing apparatus for the insulated wire 1, two first extruders 11 and two second extruders 12 are arranged in series. The feeder 1 is provided in front of the first extruder 11.
3, the air-cooling device 14 is arranged on the side of the first extruder 11 and the bonding device 15 is arranged on the side of the second extruder 12 between the extruders 11 and 12. In addition, the second extruder 1
A vulcanization pipe 16, a capstan 17, and a winder 18 are arranged on the rear side of the unit 2.

When a rubber insulated wire is manufactured by the above continuous manufacturing apparatus, the first extruder 11 is used to cover the surface of the conductor 2 supplied from the wire feeder 13 so that the semi-conductive polymer mainly composed of polyolefin is used. After the elastic layer 3 is extruded and molded, it is cooled by the air cooling device 14. Then, the adhesion device 15
After the silicone rubber adhesive layer 4 such as a primer is applied to the entire surface with the second extruder 12, the rubber insulator 5 is coated on the semiconductive layer 3 through the silicone rubber adhesive 4. Extrude into. Immediately thereafter, the insulated wire 1 is vulcanized by the vulcanization pipe 16 and continuously wound by the winder 18 via the capstan 17.

The conductor 2 is made of soft copper wire, tin, nickel,
It is a single wire or stranded wire of annealed copper wire with plating such as silver.

The semiconductive layer 13 extruded from the first extruder 11 is a polymer mainly composed of polyolefin.
For example, a mixture of polyethylene and ethylene propylene rubber is mixed with a conductivity-imparting agent such as carbon black, acetylene black, or graphite to have a specific resistance of 10 ³ to 10 ⁶ ohm · cm. The semiconductive layer 13 has a characteristic that it becomes a solidified state by cooling.

The proportion of polyethylene in the mixture of polyethylene and ethylene propylene rubber is 30% to 7%.
0% is preferable. If polyethylene is less than 30%,
When the hardness (mechanical strength) in the cooled and solidified state after molding is insufficient and exceeds 70%, when the conductivity-imparting agent is highly filled,
Mechanical strength is remarkably insufficient.

When the semi-conductive layer 13 extruded into the conductor 2 by the first extruder 11 is cooled by the air cooling device 14, the surface of the semi-conductive layer 3 is solidified and the mechanical strength is increased. As a result, the quality will be stable because it will not be damaged even if it comes into contact with the next coating device (guider chip) of the second extruder 12.

The adhesive layer 4 applied to the semiconductive layer 3 from the adhesive device 15 is provided as needed. That is, when the rubber-based insulator 5 is extruded and covered by the second extruder 12 and then vulcanized by heating and pressurizing with steam in the vulcanization pipe 16, the semiconductive layer 3 and the insulator 5 are removed. Cross-linking agent
(For example, dicumyl peroxide) is decomposed and simultaneously cross-linked, so that the semiconductive layer 3 and the insulator 5 adhere to each other.

It should be noted that the above-mentioned vulcanization by steam, not H
When crosslinking is carried out with an atmospheric pressure vulcanizer such as AV (hot air vulcanizer), the degree of adhesion that occurs when pressure is applied by steam cannot be expected. Therefore, in the case of vulcanizing with HAV, as in the above method, a silicone-based adhesive layer 4 such as a primer is provided between the semiconductive layer 3 and the insulator 5 to enhance the adhesiveness and generate voids. I try not to.

When the adhesion between the semiconductive layer and the insulator is to be improved by the above crosslinking, it is necessary to add the same crosslinking agent to the semiconductive layer 3 and the insulator 5 in order to control the crosslinking reaction. Is preferred.

The insulator 5 extruded from the second extruder 12 is preferably a silicone rubber mixture prepared by using polyorgan / siloxane as a main raw material and a silica-based reinforcing filler, a cross-linking agent and the like. ..

Since the insulated wire 1 including the conductor 2, the semiconductive layer 3, the adhesive layer 4 and the insulator 5 as shown in FIGS. 2 and 3 can be continuously manufactured by the above manufacturing method, the cost can be reduced. Can be realized. Further, when the adhesive layer 4 is unnecessary, the insulated wire 1 including the conductor 2, the semiconductive layer 4 and the insulator 5 as shown in FIGS. 4 and 5 can be continuously manufactured.

Insulated wire 1 manufactured by the above manufacturing method
Was used to test the breakdown voltage. Diameter of conductor 2 is 1.35 mm, thickness of semi-conductive layer 4 is 0.15 mm, insulator 5
Of the 1m long sample with a thickness of 2.5mm, 50cm
Was immersed in water, and a voltage was applied between the conductor 2 of the insulated wire 1 and water. The voltage was initially maintained at 20 KV for 10 minutes and then increased stepwise at a rate of 2 KV / min to measure the breakdown voltage. The bending was performed by winding the insulated wire 1 around a rod having a diameter three times that of the insulated wire 1. The results are shown in Table 1. It can be seen that the withstand voltage characteristic of bending is improved depending on the presence or absence of the semiconductive layer 3.

[0028]

[Table 1]

[0029]

As is apparent from the above description, the method for producing an insulated wire of the present invention uses a polymer mainly composed of polyolefin or the like in the semiconductive layer, and therefore, the semiconductive layer is cooled by cooling. The surface of the layer solidifies, increasing the mechanical strength. Therefore, conventional vulcanization is not required, and therefore, a method of arranging two extruders in series and continuously performing two-layer extrusion of a semiconductive layer and an insulator can be adopted. The cost can be reduced. In addition, the mechanical strength increases, so the quality is stable. Further, when a silicone-based adhesive layer such as a primer is provided by the vulcanization method, no void is generated between the semiconductive layer and the insulator, so that the withstand voltage characteristic is improved.

[Brief description of drawings]

FIG. 1 is a side view of an apparatus for manufacturing an insulated wire according to the present invention.

FIG. 2 is a side view of the insulated wire of the first example.

3 is a cross-sectional view of FIG.

FIG. 4 is a side view of an insulated wire of a second example.

5 is a cross-sectional view of FIG.

[Explanation of symbols]

 1 Insulated Wire 2 Conductor 3 Semiconductive Layer 4 Adhesive Layer 5 Insulator 11 First Extruder 12 Second Extruder 14 Air Cooling Device 15 Adhesive Device 16 Vulcanizing Pipe

Claims (5)

[Claims] 1. A conductor is coated with a plastic semiconductive layer containing a conductivity-imparting agent or the like, and the surface of the semiconductive layer is coated with a rubber insulator via a rubber adhesive layer. A rubber insulated wire characterized by the following. 2. The semiconductive layer comprises a plastic layer in which carbon black or graphite is added to a polymer mainly composed of polyolefin, and the rubber-based adhesive comprises a silicone rubber-based adhesive, and also an insulating rubber. The rubber insulated wire according to claim 1, wherein is made of silicone rubber. 3. Extruding a semiconductive layer of polymer so as to cover the conductor surface by means of a first extruder, in which two extruders are arranged in series, and then cooled, Then, a method for producing a rubber insulated wire, characterized in that a rubber-based insulator is extruded and vulcanized by a second extruder. 4. Two extruders are arranged in series and continuously extruded by a first extruder with a semiconductive layer of a polymer mainly including polyolefin so as to cover a conductor surface. Molded, cooled, then coated with a silicone rubber adhesive such as a primer, and then extruded with a second extruder to cover the rubber insulator, and then vulcanized. Electric wire manufacturing method. 5. The vulcanization by the second extruder is performed through a steam vulcanizing tube, and the semiconducting layer and the insulator are decomposed and simultaneously crosslinked to thereby form the semiconducting layer and the insulator. The method according to claim 3, characterized in that: