JP3573855B2 - Structure of oil immersion terminal of plastic cable - Google Patents

Description

【００２３】
表１の結果から、クラフト紙を２種の紙からなる二重紙とし、かつ第１の層の気密度を２０ガーレ秒以下とし、第２の層の密度を０．７ｇ／ｃｍ^３以上とした試験番号３、４、および５のものは、引張強さ、接着強度ともに良好であることがわかる。
【００２４】
上記の実験結果を考慮し、試験番号４のプラスチックラミネート紙を用いて図１に示す構造のプラスチックケーブルの油浸端末を製作し、従来品と共に、１００℃の下においたところ、従来品の絶縁性能が極端に低下したのに対して、この例のものは良好な絶縁性能を維持した。
【００２５】
【発明の効果】
以上説明したように、本発明のプラスチックケーブルの油浸端末の構造においては、油浸絶縁体を構成するプラスチックラミネート紙の引張強さが高い。また、このプラスチックラミネート紙はプラスチックフィルムとクラフト紙との接着強度が高いものである。このため、より高い温度において絶縁性能を維持することができる。また、より長期間の使用に耐えることができる。
【図面の簡単な説明】
【図１】この発明のプラスチックケーブルの油浸端末の構造の一例を示す概略断面図である。
【図２】図１に示す油浸端末に用いられるプラスチックラミネート紙の一例を示す概略断面図である。
【図３】従来の油浸端末に用いられるプラスチックラミネート紙の一例を示す概略断面図である。
【符号の説明】
１…二重クラフト紙、１ａ…第１の層、１ｂ…第２の層、
２…プラスチックフィルム、３・・・プラスチックラミネート紙、１０・・・油浸端末、１２・・・プラスチックケーブル、１６Ａ・・・油浸絶縁体[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a structure of an oil immersion terminal used for a terminal portion of a plastic cable such as a crosslinked polyethylene insulated power cable, and particularly to a structure having improved insulation reliability.
[0002]
[Prior art]
As an oil immersion terminal used at the end of a plastic cable such as a crosslinked polyethylene insulated power cable, the one shown in FIG. 1 is known. In the figure, reference numeral 10 denotes an oil immersion terminal, and reference numeral 12 denotes a plastic cable. Around the terminal end of the plastic cable 12, a plastic laminated paper 16 impregnated with an insulating oil such as silicone oil is wound many times to form an oil immersion insulator 16A. A cylindrical condenser cone 18 made of aluminum or the like is attached to the outer periphery of the oil immersion insulator 16A, and a fitting fitting tube 22 is provided on the outer periphery of the condenser cone 18 so that the condenser cone 18 and the fitting with the fitting are provided. Silicone oil 20 is filled between the tube and the tube 22.
Above these, an oil amount compensator 24 for replenishing the oil immersion insulator 16A with insulating oil and a conductor lead-out bar 26 are provided.
[0003]
In the oil immersion terminal 10 configured as described above, the plastic laminated paper 16 forming the oil immersion insulator 16A is formed by bonding a kraft paper 31 to a plastic film 32 made of polyolefin as shown in FIG. It has become. The kraft paper is provided with a plurality of linear slits (not shown) in consideration of ease of winding and elasticity.
[0004]
The production of such a plastic laminated paper is performed by extruding a molten plastic film from a T-die of an extruder and, at the same time, kraft paper is stretched along the film in a molten state, pressed by a roll, cooled and wound up. ing. For this reason, the adhesion between the plastic film of the plastic laminated paper and the kraft paper is performed by an anchor effect in which the molten plastic is embedded in fine irregularities on the surface of the kraft paper.
[0005]
If the adhesive strength between the plastic film and the kraft paper is not sufficient, the kraft paper may peel off from the plastic film. In this case, when the temperature of the oil immersion terminal employing the kraft paper becomes high, the plastic cable in the oil immersion terminal thermally expands, so that a tensile force is applied to the separated kraft paper, and the kraft paper has It may be damaged such as tearing from the slit. In such a case, the insulation performance of the oil immersion terminal using the kraft paper is reduced.
[0006]
In order to avoid this, it is conceivable to increase the adhesive strength by interposing an adhesive at the interface between the plastic film of the plastic laminated paper and the kraft paper.However, since the adhesive is generally a substance having a polar group, a dielectric substance is used. It causes deterioration of characteristics, especially dielectric loss tangent, and cannot be used.
For this reason, it is necessary to take measures to increase the adhesive strength between the plastic film and the kraft paper without using an adhesive.
[0007]
As a measure for this, it is conceivable to increase the adhesive strength by increasing the anchor effect, and for this purpose, it is conceivable to use kraft paper having low airtightness. Since kraft paper having low airtightness has large surface irregularities, the degree of embedding of the resin at the time of bonding increases, the anchor effect increases, and the adhesive strength increases.
[0008]
However, low density kraft paper generally has low density. Low density kraft paper usually has low tensile strength. For this reason, the oil immersion terminal of a plastic cable employing such a plastic laminated paper using kraft paper may be heated to a high temperature, especially 80 ° C. or higher, due to heat generated by lead work at the time of connection or heat generated by energization. When exposed to water, the plastic laminated paper in the oil immersion terminal sometimes receives a tensile force due to thermal expansion of the plastic cable and may be damaged such as tearing. As a result, the insulation performance of the oil immersion terminal was sometimes reduced.
[0009]
[Problems to be solved by the invention]
Therefore, an object of the present invention is to provide a structure of an oil immersion terminal of a plastic cable which can maintain good insulation performance even at a high temperature.
[0010]
[Means for Solving the Problems]
The structure of the oil immersion terminal of the plastic cable of the present invention is such that the kraft paper constituting the plastic laminated paper is a multi-layered paper composed of two or more layers of paper, and the air tightness of the layer in contact with the plastic film among these layers. 20 gale seconds or less, and the density of the layer exposed on the surface is 0.7 g / cm ³ or more.
It is preferable to use a film made of a polypropylene homopolymer as the plastic film from the viewpoint of insulating performance.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 2 shows an example of a plastic laminated paper used for the oil-immersed insulator having the structure of the oil-immersed terminal according to the present invention. In the figure, reference numeral 1 denotes a double kraft paper comprising two layers 1a and 1b. , 2 is a plastic film. The double kraft paper 1 is integrally bonded to one side of the plastic film 2 to form a plastic laminated paper 3.
The airtightness of the first layer 1a of the double kraft paper 1 is set to 20 Gale seconds or less. If the airtightness exceeds 20 Gare seconds, the adhesion to the plastic film is inferior, and the kraft paper tends to peel off.
In addition, the density of the second layer 1b is set to 0.7 g / cm ³ or more. If the density is less than 0.7 g / cm ³ , the tensile strength of the oil-immersed insulator decreases, and the second layer 1b is easily damaged. Become.
[0012]
Further, the thickness of the double kraft paper 1 is not particularly limited, but is usually in the range of 20 to 100 μm, and the thickness of the first layer 1 a is at least 5 μm or more, preferably 5 to 30 μm. On the other hand, the thickness of the second layer 1b is at least 15 μm or more, and preferably in the range of 15 to 70 μm. If the thickness of the first layer 1a is less than 5 μm, sufficient adhesive strength with the plastic film cannot be obtained, and if the thickness of the second layer 1b is less than 15 μm, the tensile strength will be insufficient.
[0013]
Furthermore, as for the ratio of the thickness of the first layer 1a and the second layer 1b to the total thickness of the double kraft paper 1, the smaller the ratio of the first layer 1a, the more advantageous. This is because the area involved in the adhesiveness is a relatively thin portion of the surface, and if the unevenness of the surface in this portion is large, sufficient adhesive strength can be obtained. This is because the tensile strength is improved.
The double kraft paper 1 is preferably a low-loss deionized water-washed paper having good dielectric properties, and a low conductivity paper having an immersion liquid conductivity (according to JIS-C-2111) of 15 μS / cm or less. Is preferred.
Such a double kraft paper 1 is manufactured by a method in which pulp having a different degree of fibrillation of paper fibers is stacked in two stages when paper is made by a fourdrinier or round net type paper machine or the like.
[0014]
Then, the first layer 1a of the double kraft paper 1 is combined with the plastic film 2 so that the first layer 1a is in contact with the plastic film 2, and the second layer 1b is exposed on the surface.
[0015]
The plastic film 2 is made of non-polar polyolefin such as polypropylene, poly-4-methylpentene-1, polybutene-1, polyethylene, or fluorine such as tetrafluoroethylene-hexafluoropropylene copolymer or ethylene-tetrafluoroethylene copolymer. It is made of resin and has a thickness of 20 to 150 μm. Among these plastics, a film made of a polypropylene homopolymer, preferably a polypropylene homopolymer having a relatively low melt viscosity of 5 to 50 g / 10 min in the melt index has a high adhesiveness to the double kraft paper 1, and The insulating properties of the resulting laminated paper are also good, which is preferable.
[0016]
In addition, when the plastic film 2 and the double kraft paper 1 are bonded, a molten film is extruded from a T-die of an extruder, and when the film is in a molten state, the double kraft paper 1 is placed along the film 2 and pressed. It is manufactured by a so-called extrusion lamination method in which a roll is pressed.
The total thickness of such a plastic laminated paper is in the range of 100 to 300 μm, but may be outside this range depending on the application.
[0017]
In the plastic laminated paper 3 having such a configuration, since the first layer on the plastic film 2 side of the double kraft paper 1 laminated on the plastic film 2 has low air density, it is porous and uneven on the surface. Is increased, and at the time of bonding with a plastic film, the penetration of the molten plastic into the paper is improved, and the adhesive strength is improved.
Further, since the second layer on the front side of the double kraft paper 1 has a high density, the tensile strength and the elongation of the plastic laminated paper 3 are high.
[0018]
Further, the kraft paper may be a multi-layer kraft paper having three or more layers, and also in this case, the air density of the layer in contact with the plastic film is 20 Gale seconds or less, and the density of the surface side layer is 0.7 g / cm ³ or more. Should be fine. In this case, the intermediate layer preferably has a high density of 0.7 g / cm ³ or more in terms of tensile strength and elongation.
[0019]
In the oil immersion terminal having the structure shown in FIG. 1 in which the oil immersion insulator is formed using such a plastic laminated paper, the kraft paper constituting the plastic laminated paper and the plastic film have high adhesive strength. Is less likely to occur. Further, since the kraft paper has a high tensile strength and a high elongation, even if the plastic cable in the terminal is thermally expanded at a high temperature, the plastic laminated paper withstands the tensile tension and is not damaged. Therefore, the oil immersion terminal can maintain the insulation performance at a higher temperature.
[0020]
Hereinafter, specific examples will be shown to clarify the operation and effect.
(Test example)
A polypropylene having a melt index of 15.0 g / 10 min and a density of 0.90 g / cm ³ is melt-extruded at a temperature of 280 ° C. to form a polypropylene film. While the polypropylene film is in a molten state, kraft paper having a thickness of 70 μm is rolled and roll-pressed. A polypropylene laminated paper having a total thickness of 130 μm was produced.
As the kraft paper, a normal single paper having a thickness of 70 μm and a double paper in which two papers each having a first layer having a thickness of 20 μm and a second layer having a thickness of 50 μm were used.
This double kraft paper is made of immersion liquid having a conductivity of 5 μS / cm according to JIS-C-2111 by deionized water washing. The first layer is on the polypropylene film side and the second layer is on the surface side. Turned to.
[0021]
This polypropylene laminated paper is immersed in insulating oil (JIS-C-2320-193 6 kinds of silicone oils) at 100 ° C. for 24 hours, and then the adhesive strength at the interface between the polypropylene film and the double kraft paper (180 ° peel test) ) Was measured.
Further, the tensile strength (JIS-C-2111) of this polypropylene laminated paper was measured.
Table 1 shows the results.
[0022]
[Table 1]

[0023]
From the results in Table 1, the kraft paper is a double paper made of two types of paper, and the air density of the first layer is 20 Gale seconds or less, and the density of the second layer is 0.7 g / cm ³ or more. Test Nos. 3, 4, and 5 show that both tensile strength and adhesive strength are good.
[0024]
In consideration of the above experimental results, an oil immersion terminal of a plastic cable having the structure shown in FIG. 1 was manufactured using the plastic laminated paper of Test No. 4 and was placed at 100 ° C. with the conventional product. While the performance was significantly reduced, this example maintained good insulation performance.
[0025]
【The invention's effect】
As described above, in the structure of the oil immersion terminal of the plastic cable of the present invention, the tensile strength of the plastic laminated paper constituting the oil immersion insulator is high. Further, this plastic laminated paper has a high adhesive strength between the plastic film and the kraft paper. Therefore, the insulation performance can be maintained at a higher temperature. In addition, it can withstand longer-term use.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing an example of the structure of an oil immersion terminal of a plastic cable according to the present invention.
FIG. 2 is a schematic sectional view showing an example of a plastic laminated paper used for the oil immersion terminal shown in FIG.
FIG. 3 is a schematic sectional view showing an example of a plastic laminated paper used for a conventional oil immersion terminal.
[Explanation of symbols]
1 ... double kraft paper, 1a ... first layer, 1b ... second layer,
2 ... Plastic film, 3 ... Plastic laminated paper, 10 ... Oil immersion terminal, 12 ... Plastic cable, 16A ... Oil immersion insulator

Claims (1)

An oil-immersed insulator formed by winding a plastic laminated paper impregnated with insulating oil is provided on the outer periphery of the end portion of the plastic cable,
The plastic laminated paper is composed of a plastic film and kraft paper bonded to one side of the plastic film,
This kraft paper is a multi-layer paper made of two or more layers of paper, and among these layers, the air tightness of the layer in contact with the plastic film is 20 Gale seconds or less, and The structure of an oil immersion terminal of a plastic cable, wherein the density of the layer is 0.7 g / cm ³ or more.

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