JPH0334008Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Technical Field> The present invention relates to a gas-impregnated cable formed by winding a plastic film tape around a conductor to form an insulating layer and filling the cable with an insulating gas.

<Background Art and Conventional Problems> Conventionally, in gas-impregnated cables wrapped with plastic film tape used as power cables, etc., in order to obtain gas flowability, plastic film tapes with rough surfaces are generally used. However, methods for roughening the tape include forming uneven parts on the surface of the film by pressing with a mold, and (b) stretching a sheet made by kneading two or more polymers with different properties. Depending on the difference in stretchability of each polymer, there are two methods: a method of forming microprotrusions, a method of forming a rough surface by stretching an unstretched film having columnar β-type crystals on the surface layer under certain conditions, and a method of forming a rough surface. Resin contains various particles such as glass particles, short glass fibers, etc.
A method is already known in which a mixture of other hard resin pieces is extruded or subsequently stretched, and uneven parts are formed by protruding portions of the particles themselves from the tape surface.

However, in each of the above methods,
According to the extrusion process using the mold described in A, there was a problem that the uneven portions tend to return to their original shape due to thermal history, resulting in a decrease in gas flowability. Furthermore, in the case (B) of kneading and stretching different types of polymers and in the case (C) of β-type crystals, it is difficult to obtain a large surface roughness of the film, and there is also the problem that sufficient gas flowability cannot be obtained. Furthermore, in the case of extrusion, stretching, etc. by mixing particles (d), the adhesion (compatibility) between the mixed particles and the base resin is generally poor, resulting in a decrease in strength when made into a tape, and the presence of particles during stretching. There were problems such as parts breaking.

<Purpose of the invention> The present invention was devised in view of these conventional problems, and is basically a method of mixing particles. It is an object of the present invention to provide a gas-impregnated cable using a plastic film tape having sufficient unevenness.

<Disclosure of the Invention> In order to achieve the above-mentioned object, the present invention is a plastic film tape that is wound on a conductor to form an insulating layer, and is made by adding a resin that is compatible with the base resin to a plastic base resin. The gas-impregnated cable is made of a cross-linked particle having a gel fraction (according to JISC3005 method) of preferably 30 to 70%. According to this configuration, since the mixed particles are resins that are compatible with the base resin, they naturally have good adhesion to the base resin and are bonded together. Therefore, the strength of the tape does not decrease, and it does not break during stretching or the like. Further, since the mixed particles are crosslinked with an appropriate gel fraction, the particles do not lose their shape when melted during tape molding, and a sufficiently rough surface can be obtained.

In other words, when manufacturing the cable, the desired tension can be applied and the cable can be wound at high speed.
In this case, it is possible to obtain a gas-impregnated cable that has no risk of breakage, has good productivity, and has excellent gas flowability due to the uneven rough surface.

In this invention, the gel fraction of the crosslinked particles to be mixed is set to 30 to 70% according to the JISC3005 method because if the gel fraction exceeds 70%, the adhesiveness with the base resin will decrease. If it is less than 30%, the particles will melt and lose their shape during tape molding, making it impossible to form sufficient unevenness.

In addition, the base resin used is not particularly limited, but for example, polypropylene (PP),
Examples include polyethylene (PE) and polymethylpentene (TPX), and the mixed particles are crosslinked products corresponding to these.

<Examples> The present invention will be further explained in detail below with reference to illustrated examples.

FIG. 1 shows an example of a gas-impregnated cable according to the present invention, in which 1 is a conductor, 2 is an insulating layer, and 3 is a sheath. As mentioned above, the insulating layer 2 of this cable is made by wrapping a plastic film tape 4 made of a base resin and containing crosslinked particles having a gel fraction of 30 to 70%, which is compatible with the base resin. It is formed as follows.

The specific configuration of this tape 4 is not particularly limited as long as it satisfies the above conditions, and it may be unstretched. However, when it is wound on a conductor as a cable, a certain amount of tension is applied using a tape winding machine. Stretching is preferable because it is necessary to wrap the film in such a way as to prevent wrinkles from occurring. In actual use, this tape 4 may be wound alone, but it is preferably used in a laminated structure as shown in FIGS. 2A and 2B.

In the case of FIG. 2A, a normal plastic film tape 7 is pasted on one side of a plastic film tape 4 made of a base resin 5 mixed with crosslinked particles 6. More specifically, a plastic film tape 4 containing polypropylene as a base resin and crosslinked polyethylene as particles is extruded and stretched, and an unstretched tape 7 of polymethylpetene is laminated thereon.

In the case of FIG. 2B, plastic films 4, 4 each containing a base resin 5 and crosslinked particles 6 are bonded to each other. More specifically,
One (upper) tape 4 is an unstretched plastic film tape containing polymethylpentene as a base resin and crosslinked polypropylene particles, and the other (lower) tape 4 is an unstretched plastic film tape containing polypropylene as a base resin and particles as crosslinked polypropylene. It is bonded together as a stretched plastic film tape blended with cross-linked polypropylene.

According to these laminate structures, the film tape itself containing crosslinked particles has a high strength due to the characteristics of the particles (the degree of crosslinking is a resin that is compatible with the base resin and has an optimal gel fraction), as described above. There is almost no deterioration, and since either one of them is stretched, the strength is improved and it can smoothly respond to the tension of the tape winding machine. That is, it can be wound at high speed without wrinkles. Furthermore, since the laminate structure increases the thickness of the entire tape, the number of turns can be reduced in forming the insulating layer, and productivity can also be improved from this perspective.

In addition, in the winding tape of the above example, one of the tapes was stretched,
It is also possible to stretch both tapes, and the combination of the upper and lower tapes can take various forms, such as using the same resin.
In addition, although the cable of the above embodiment is generally composed of a conductor, an insulating layer, and a sheath, in the case of the present invention, other configurations that are normally required, such as
Of course, inner and outer semiconducting layers, shielding layers, etc. can be provided as necessary.

<Industrial Applicability> As described above, the gas-impregnated cable according to the present invention has good productivity due to the strength and thickness of the plastic film tape wound around it, and also has good gas flowability, making it suitable for high voltage applications. Useful as cables, particularly suitable as power cables.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional end view of a gas-impregnated cable according to an embodiment of the present invention, and FIGS. 2A and 2B are side views showing each structure of a plastic film tape. 1... Conductor, 2... Insulating layer, 4... Plastic film tape, 5... Base resin, 6...
crosslinked particles.

Claims (1)

[Scope of utility model registration request] In a gas-impregnated cable formed by winding a plastic film tape around a conductor to form an insulating layer and filling it with an insulating gas, the plastic film tape is made of a plastic base resin having good compatibility with the base resin. A gas-impregnated cable characterized in that it uses a tape made of resin and compounded with crosslinked particles whose gel fraction is 30 to 70% according to JISC3005 method.