JPS6367287B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an improved gas-impregnated power cable formed by winding a plastic film tape around a conductor to form an insulating layer and pressurizing an insulating gas into the cable. Traditionally, F (oil-filled) has been used as a power cable.
Cables and GF (gas-filled) cables have been put into practical use, and cellulose-based insulating paper is mainly used as the insulating tape for these cables.In recent years, however, cellulose-based insulating paper has been used, but in recent years, cellulose-based insulating paper has been developed that has superior insulation strength and lower dielectric loss than insulating paper. Plastic film, which inherently has the property of being easily dried and degassed, is being considered as an insulating material. Among these, gas-impregnated cables (hereinafter referred to as GF cables), which are made by winding multiple layers of film to form an insulator and filling the insulation layers with a gas (such as SF ₆ ) having high dielectric strength, are combustible. It has been attracting attention in recent years as it is advantageous from the perspective of disaster prevention because it does not use any harsh insulating oil. However, in GF cables that use paper such as cellulose paper used in oil-immersed cables or non-uniform structures such as non-woven cloth or synthetic paper, the effect of suppressing discharge when discharge occurs in the gas part is At present, it cannot be expected to be a cable that can be put to practical use. Therefore, it was considered to use a homogeneous smooth film made of polyethylene or polypropylene that has the effect of inhibiting discharge, but when wound in multiple layers, the air permeability between the film layers was poor, and vacuum degassing and gas impregnation could not be performed sufficiently. It had the disadvantage that it was not. As countermeasures against this problem, methods such as slicing the film surface, applying powder to the film surface, and applying unevenness to the film surface by embossing have been attempted. Groove processing damages the film, and powder adhesion methods have the drawbacks of uneven adhesion and movement of the powder.Furthermore, although embossed textured films have no problem with gas flow, they do not allow the insulating film to be used as a conductor. When the cable is wound on top of the cable, the thermal resistance is usually 1000% due to the large proportion of air gaps between the insulation layers.
The temperature is extremely high, exceeding ℃・cm/W, and heat radiation is insufficient, making it difficult to make a cable that can be put to practical use. In addition, to improve the bending resistance of the cable,
It is conceivable to mix silicone oil or the like into the film that forms the insulating layer, but ordinary silicone oil has poor compatibility with polyolefin and does not have good slipperiness immediately after molding (or film formation). However, it is not only difficult to maintain slipperiness over a long period of time due to oil desorption from the polymer matrix over time, but also when silicone oil is added during film formation. Polypropylene resins have had drawbacks such as non-uniform fluidity during melting, causing surging, and making it difficult to obtain a film with a uniform thickness suitable for practical use. The object of the present invention is to eliminate the drawbacks of the prior art described above, and to provide a
The company intends to provide GF cables. In order to achieve the above object, the present invention has the following structure as its main structure. That is, in a gas-impregnated power 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 biaxially stretched polypropylene with a thickness of 40 to 300 μm. A film is used as a base, at least one side of the base is coated with a layer consisting of a mixture of the following polymers (a), (b), and (c), and the surface of the polymer mixture layer is JIS
Maximum roughness R _nax by BO 601−1976 method is 0.1μ
This gas-impregnated power cable is characterized in that it uses a laminated film with an R _nax of 20μ and the number of protrusions with a height of 1μ or more is 1/1mm or more in at least one direction. (a) Polypropylene resin of 1.0 [η] 3.0,
100 parts by weight, (b) one or two polymers having at least one bond selected from the following in the skeleton structure;
A mixture of more than one species whose weight average solubility parameter value is 8.5 or more, 0.5
~50 parts by weight,

【formula】

【formula】

【formula】

【formula】

[Formula] (c) 0.1 to 20 parts by weight of one or a mixture of two or more selected from the following modified silicone oils (i) and (ii), (The value of m is an integer greater than or equal to 1, and the values of X and Y are 0.05≦
X/X+Y≦1) (R ₁ , R ₂ , R ₃ , R ₄ are C ₁ to C ₂₀ alkyl groups or aralkyl groups; the value of m is 1, 2, 3, or 4; the values of X and Y are 0≦X/X+Y≦ 0.95) In the laminated film with fine irregularities (hereinafter abbreviated as paper-like film) used as the insulating layer of the gas-impregnated power cable of the present invention, the biaxially stretched polypropylene film used as the base layer is very commonly used. A homopolymer of propylene is used. However, it is also possible to use copolymers in which other aliphatic olefins (having 2 to 6 carbon atoms) are copolymerized in very small amounts, that is, not exceeding 2% by weight. The degree of isotacticity measured in the boiling heptane extraction residue is 90-98%, ASTM D-
Melt index measured under 1238-73 conditions (230℃, load 2160g) is 0.5-20g/10min
Those in the range between are preferably used. In the biaxially oriented polypropylene film layer, other polyolefins (polyethylene, polypropylene, poly-4-methyl-pentene, polystyrene, cis-1,2-polybutadiene), which have low film dielectric loss and excellent dielectric strength, are used. Alternatively, a small amount of polymer other than polyolefin (polyethylene terephthalate, polysulfone, polycarbonate, etc.) may be added in a small amount of 10 parts by weight or less per 100 parts by weight of polypropylene as long as the electrical properties and mechanical strength of the film are not deteriorated. Of course, various known additives (stabilizers, plasticizers, lubricants, inorganic fillers, nucleating agents, crosslinking agents, etc.) may be added and mixed into this polypropylene film. The birefringence of the biaxially stretched polypropylene film layer is not particularly limited, but is usually (100 to 250).
It is preferably in the range of ×10 ^-4 . Thickness of biaxially stretched polypropylene film (d ₂ )
is preferably in the range of 40 to 300μ, more preferably in the range of 100 to 200μ. In order to avoid the occurrence of buckling wrinkles in the cable, it is desirable that the tape be thicker, but on the other hand, the impulse breaking strength generally tends to decrease as the thickness increases (thickness effect); , the film thickness is preferably 200μ or less. Considering the above two factors, 2
The thickness of axially stretched polypropylene film is 40 ~
It was concluded that the thickness is preferably 300μ, more preferably in the range of 100 to 200μ. Further, the thickness (d ₁ ) of the polymer mixture layer forming the paper-like film is preferably in the range of 0.005d ₁ /d ₂ 0.2 with respect to the biaxially stretched polypropylene base layer, and more preferably, It is preferable that it be in the range of 0.01d ₁ /d ₂ 0.1. When d ₁ /d ₂ exceeds 0.2, the impulse rupture strength decreases, which is not preferable. Furthermore, since the Young's modulus of the polymer mixture layer is inferior to that of the biaxially stretched polypropylene layer of the substrate, d ₁ /d ₂ is 0.2.
If it exceeds this, the rigidity of the paper-like film decreases, and buckling wrinkles are likely to occur due to bending of the cable, which is undesirable. On the other hand, when d ₁ /d ₂ is less than 0.005, it becomes difficult to create sufficient gaps between the insulating layers to ensure gas flow. In order to prevent the insulating layer from undergoing permanent deformation due to the bending stress that is applied when the cable is bent or when the cable is laid, the Young's modulus of the paper-like film in the present invention (unit: Kg/mm ² ) x the paper-like film's It is preferable that the thickness (μ) value is 10 ⁴ or more. More preferably, this value is 2.0×10 ⁴ or more. At least one side of the paper-like film used in the present invention has a maximum roughness according to the JIS BO 601-1976 method.
It is desirable that the R _nax value is in the range of 0.1 μR _nax 20 μ. More preferably, the range is 1 μR _nax 10 μ. When the R _nax value is less than 0.1μ, the thermal resistance value is sufficiently low to a satisfactory level, but the gas flowability is insufficient and it cannot be used as a practical cable. on the other hand,
On the other hand, when the R _nax value exceeds 20μ, the gas flowability is improved to a satisfactory level, but the thermal resistance is
Since the temperature exceeds ~1500°C/cm/W and heat dissipation is insufficient, it cannot be a cable that can be put to practical use. Regarding the density of protrusions on the film surface, the height
The number of protrusions of 1 μ or more is at least in one direction,
It is necessary that there be 1 piece/1mm or more. If the number of protrusions is less than 1/1 mm, there is a problem in that sufficient flowability cannot be obtained to ensure movement of the insulating gas in response to bending changes of the cable. The resin mixture layer having fine irregularities in the paper-like film used in the present invention is made by stretching a film of a blend of polypropylene resin, a polymer with a solubility parameter value of 8.5 or more whose compatibility with polypropylene is insufficient, and modified silicone oil. It is formed by It is well known that stretching a blend of polymers with poor compatibility with each other can result in a whitened sheet or the formation of voids or micropores within the film. The stretched sheet of a blend with a polar polymer with a value (hereinafter referred to as SP value) of 8.5 or higher has minute irregularities, and this uneven surface is effective in achieving both flowability and thermal resistance in gas insulated cables. This method has been found to be extremely effective. The polypropylene used as a component of the resin mixture layer preferably has a [η] of 1.0 or more and 3.0 or less, more preferably 1.3 or more and 2.5 or less, as measured in tetralin at 135°C. . Although the solubility parameters of incompatible polymers can be determined experimentally, a simpler method is to use the additivity of the cohesive energy constant.
It can be calculated by Small's method (Encyclopedia of Polymer Science and
technology 3 , 855 (1965), Interscience
Publisher). According to this method, the solubility parameter value of polypropylene is
It is 8.0. Incompatible polymers used in the above process include folysulfone (SP value 8.7), polyethersulfone, polycarbonate (SP value 9.7), polyethylene terephthalate (SP value 9.1), polybutylene terephthalate, polyethylene terephthalate-isophthalate copolymer. Examples include, but are not limited to, polybutylene terephthalate-isophthalate copolymer, polyphenylene oxide (SP value 8.8), polyphenylene sulfide, etc.
Polymers of 8.5 or higher can be selected and used as appropriate. When using two or more types of incompatible polymers, they must be selected so that the weight average value of their solubility parameter values is 8.5 or more. The blend ratio of polypropylene () and incompatible polymer () is preferably such that 0.5 to 50 parts by weight of () is added to 100 parts by weight of ().
It is preferable to add 5 to 20 parts by weight, which is sufficient for the surface unevenness, but in order to further increase the density of the protrusions, it is necessary to add particulate matter that is non-conductive and resistant to insulating gas. Inorganic or organic particles having an average particle size of 0.1 μm or more and 20 μm or less may be added. In this case, the amount added is 20 parts by weight or less per 100 parts by weight of polypropylene in order to reduce the occurrence of film tearing, etc.
Examples of the particulate materials include calcium carbonate, glass fine powder, calcium silicate, silicon oxide, talc, clay, Teflon fine particles, and ultra-high molecular weight polyethylene powder. The special silicone oil used in the present invention is
It is one type or a mixture of two types selected from the following modified silicone oils (i) and (ii). (The value of m is an integer greater than or equal to 1, and the values of X and Y are 0.05≦
X/X+Y≦1) (R ₁ , R ₂ , R ₃ , R ₄ are C ₁ to C ₂₀ alkyl groups or aralkyl groups, the value of m is 1, 2, 3, or 4, the values of X and Y are 0≦X/X+Y ≦0.95) The amount of modified silicone oil mixed is preferably 0.1 parts by weight or more and 20 parts by weight or less based on 100 parts by weight of the polypropylene resin forming the paper layer.
More preferably, the amount is 0.5 parts by weight or more and 5 parts by weight or less. If the amount is less than 0.1 parts by weight, the effect of imparting slipperiness to the insulating layer film will be poor, and if it exceeds 20 parts by weight, the ejection stability during melt extrusion of the paper layer will deteriorate, so it is difficult to maintain a uniform thickness. It is difficult to obtain the desired protrusion height and roughness density. As for the length of the alkyl chain of silicone oil (i), m is preferably 1 or more, more preferably 5 or more. When m is 0 (corresponding to dimethylsiloxane oil), the silicone oil (i) has poor compatibility with the polypropylene resin, and therefore cannot impart slipperiness to the insulating layer film over a long period of time. Therefore, the value of m is 1
The above is good. The copolymerization composition ratio of alkyl-modified siloxane units and dimethylsiloxane units is preferably in the range of 0.05≦X/X+Y≦1, more preferably 0.2≦
It is preferable that X/X+Y≦1. When X/X+Y is less than 0.05, the compatibility between the silicone oil (i) and the polypropylene resin is insufficient, resulting in a drawback that the slipperiness decreases over time after film production. The copolymerization composition ratio of siloxane units and silalkylene units in silicone oil (ii) is 0≦
It is preferable that X/X+Y≦0.95, more preferably 0≦X/X+Y≦0.80. When X/X+Y>0.95, the compatibility between the silicone oil (ii) and the polypropylene resin is insufficient, making it difficult to maintain slipperiness over a long period of time. Ordinary dimethylsiloxane oil may be added to the modified silicone oil of the present invention. However, the amount of dimethylsiloxane oil added is 60% by weight or less, preferably 40% by weight or less of the sum of the weight of modified silicone oil and the weight of dimethylsiloxane oil, and the amount of dimethylsiloxane oil The sum of the weights is based on 100 parts by weight of polypropylene resin.
It is preferably in the range of 0.1 to 20 parts by weight, more preferably 0.5 to 5 parts by weight. If the amount of dimethylsiloxane oil added exceeds 60% of the sum of both oils, the effect of the modified silicone oil will decrease and the slipperiness will decrease over time, which is not preferable. In order to prepare a paper-like film having minute irregularities, it is most advantageous to utilize a composite film forming process. Specifically, using a composite cap,
Three-layer structure of (polypropylene + incompatible polymer + modified silicone oil) / polypropylene / (polypropylene + incompatible polymer + modified silicone oil) or two-layer structure of (polypropylene + incompatible polymer + modified silicone oil) / polypropylene A composite unstretched sheet of
This can be prepared by biaxially stretching it. Or on one or both sides of a polypropylene film that has been uniaxially stretched in advance (polypropylene + incompatible resin + modified silicone oil)
It can also be produced by extrusion laminating the blend, then introducing the composite film into a tenter and transversely stretching it. or,
It can also be produced by dry laminating a film having minute irregularities prepared by the above process on at least one side of a smooth polypropylene film. The gas-impregnated power cable of the present invention is manufactured by winding the above-mentioned film having minute irregularities on a conductor as an insulating layer. An example of the GF cable of the present invention is the single-core gas-impregnated cable shown in the accompanying drawings. That is, 1 is a gas flow path, and 2 is a hollow spiral tube forming a central gas flow path in the metal conductor 3. 4 is a conductive layer, and 5 is an insulating layer made of paper-like film. 6 is an insulating and hard layer, 7 is a metal sheath, and 8 is a corrosion-resistant layer. The gas-impregnated power cable of the present invention uses a paper-like film containing special silicone oil and having a special surface morphology as an insulator, so it has excellent insulating gas air permeability, heat dissipation property, and bending resistance. It has the following effects. Naturally, the gas-impregnated power cable of the present invention is not limited to the single-core cable shown in the drawings, but may include a plurality of single-core cables in which at least a paper-like film is wound around a conductor having a gas passage. It includes a multi-core power cable made up of a collection of books. Hereinafter, embodiments and effects of the present invention will be explained with reference to Examples, but the present invention is not particularly limited thereto. Example 1 Polypropylene pellets (boiled heptane extraction residue 96%, melt index 2.0) were melt extruded from a die at 280°C, cooled and solidified on a casting drum at 30°C, and an unstretched sheet with a thickness of about 3.6 mm was obtained. I made it. While heating this sheet to 125℃,
It was stretched 5 times in the longitudinal direction to form a uniaxially stretched sheet.
Apply the following resin mixture to one side of this sheet at 270°C.
Extrusion laminated. (a) 100 parts by weight of polypropylene resin ([η] = 2.23 measured in Tetralin), (b) 10 parts by weight of polysulfone (Udel1700 manufactured by UCC), (c) 2.5 parts by weight of the following alkyl silicone oil (100 centistokes) Department, Guide this laminate into the tenter and
The film was stretched 8.5 times (stretching temperature 160°C), then heat treated at 160°C for 6 seconds while relaxing 5% in the width direction, cooled, and wound up. The thickness of the resulting film was approximately 115μ, with a biaxially oriented polypropylene layer.
The thickness of the layer made of the resin mixture was 25μ. The Young's modulus of this film is 160Kg/mm ² in the longitudinal direction,
The width direction was 270Kg/ ^mm2 . Cut this film into a 70mm x 70mm square and load
When the coefficient of friction between the paper-like surface and the smooth surface was measured at 200 g and a pulling speed of 15 cm/min, the static friction coefficient and kinetic friction coefficient showed extremely low values of 0.21 and 0.18, respectively. The R _nax value of the rough side of this film according to the JIS BO 601-1976 method is that the number of protrusions with a protrusion height of 1μ or more is:
There were 13 pieces/1 mm in the longitudinal direction and 14 pieces/1 mm in the axial direction. This film is slit to 22mm width and 40mm
Wound to a thickness of 20 mm on a conductor of φ (tension at the time of winding is 1
Kg/22mm width), a model cable was created. After degassing by vacuum suction, we filled it with SF ₆ gas (gas pressure 6Kg/cm ² ) and checked the thermal resistance value and air permeability, and found that the thermal resistance value was 670℃・cm/W, The airflow resistance was 2.1×10 ³ g·sec/cc·cm ² , indicating a performance sufficient for practical use as a GF cable. When this model cable was subjected to a 2000D back-and-forth reciprocation test, tape wrinkles,
There were no tape breaks or gap disturbances, and the condition remained exactly the same as immediately after taping. Incidentally, after performing the vent test, an impulse destruction test was performed on the cable, and as a result, the impulse destruction strength was extremely good at 1720KV. Example 2 Polypropylene pellets (boiling heptane extraction residue 96%, melt index 2.0) were melt extruded from a die at 280°C, cooled and solidified on a casting drum at 30°C, and unstretched to a thickness of approximately 4.0 mm. I made a sheet. While heating this sheet to 125℃,
It was stretched 5 times in the longitudinal direction to form a uniaxially stretched sheet.
The following resin mixture was extruded and laminated on one side of this sheet at 270°C. (a) 100 parts by weight of polypropylene resin ([η] = 2.23 measured in Tetralin) (b) 10 parts by weight of polysulfone (Udel1700 manufactured by UCC) (c) 1 part by weight of dimethylpolysiloxane (50 centistokes) (d ) 2 parts by weight of the following alkyl silicone oil (100 centistokes) Guide this laminate into the tenter and
The film was stretched 8.5 times (stretching temperature: 160°C), then heat treated at 160°C for 6 seconds while relaxing 5% in the width direction, cooled, and wound up. The thickness of the obtained film was approximately 110μ, and the biaxially oriented polypropylene layer was
The thickness of the layer made of the resin mixture was 10μ. The Young's modulus of this film is 170Kg/mm ² in the longitudinal direction,
It was hot. Cut this film into a 70mm x 70mm square and load
When the coefficient of friction between the paper-like surface and the smooth surface was measured at 200 g and a pulling speed of 15 cm/min, the static friction coefficient and kinetic friction coefficient showed extremely low values of 0.22 and 0.20, respectively. The rough surface side of this film has an R _nax value of 5.1μ according to the JIS BO 601-1976 method, and the number of protrusions with a height of 1μ or more is 11/1 mm in the longitudinal direction and 12 in the width direction.
pieces/1mm. This film was slit to a width of 22mm and wound to a thickness of 20mm on a 40mmφ conductor (tension at the time of winding was 1Kg/22mm width) to create a model cable. After degassing with vacuum suction,
When filled with SF ₆ gas (gas pressure 6Kg/cm ² ) and examined the thermal resistance value and air permeability, the thermal resistance value was 680.
°C・cm/W, ventilation resistance is 1.9×10 ³ g・sec/cc・
cm ² and showed sufficient performance for practical use as a GF cable. About this model cable,
When the 2000D was vented twice in the opposite direction, there were no tape wrinkles, tape breaks, or gap disturbances, and the tape remained in exactly the same condition as immediately after taping. Incidentally, after performing the vent test, an impulse destruction test was performed on the cable, and as a result, the impulse destruction strength was extremely good at 1750KV. Example 3 A uniaxially stretched polypropylene sheet was prepared in the same manner as in Example 1, and the following resin mixture was extruded and laminated on both sides of this sheet at 270°C. (a) 100 parts by weight of polypropylene resin ([η] = 1.85), (b) 5 parts by weight of polysulfone (Udel1700), (c) 0.5 parts by weight of dimethylpolysiloxane (25 centistokes), (d) Dimethylsiloxane-sil below 3.0 parts by weight of methylresiloxane copolymer (100 centistokes), The obtained laminated sheet was guided into a tenter and
Stretched 8.5 times in the width direction at ℃, then stretched 5 times in the width direction
After heat treatment at 160° C. for 6 seconds while relaxing the sample, the sample was cooled and rolled up. The thickness of the resulting film was approximately 135μ, with a biaxially oriented polypropylene layer.
A layer of 110μ resin mixture was about 12μ each on both sides. The Young's modulus of this film is
It showed a value of 160Kg/mm ² and 295Kg/mm ² in the width direction. The static friction coefficient and dynamic friction coefficient of this film were 0.21 and 0.19, respectively. The R _nax value of the film surface is 10 μ on both the top and bottom surfaces, and the number of protrusions with a height of 1 μ or more is 16/1 mm in the longitudinal direction and 1 mm in the width direction.
There were 15 pieces/1mm. Using this film, a model cable was prototyped in the same manner as in Example 1, and the thermal resistance value and air permeability were examined.The thermal resistance value was
760℃・cm/W, ventilation resistance is 9×10 ³ g・sec/
cc cm ² , and showed satisfactory performance as a GF cable. About this model cable,
When we conducted a venting test of 2000D twice in the opposite direction and examined the state of wrinkles after disassembling the cable, there were no tape wrinkles, tape breaks, or gap disturbances, and the cable was in exactly the same condition as immediately after taping. Incidentally, after conducting the vent test, an impulse breaking test was conducted on the cable, and the result was that the impulse breaking strength was 1690 KV, which was good. Example 4 For a model cable created with the same specifications as Example 1, the relationship between SF ₆ gas pressure and partial discharge was investigated. Next, the cable was subjected to a venting test of 2000D in the opposite direction and back and forth twice, and then SF ₆ gas was applied at a gas pressure of 6Kg/cm ² G.
A long-term test was conducted by filling the battery with 200 KV of AC voltage at 50 Hz and applying a current that brought the conductor temperature to 85°C for 8 hours a day (24 hours). After the one-month long-term test, the partial discharge characteristics were investigated again, and as shown in FIG. 2, the same good characteristics as in the initial stage were obtained. Next, an impulse breakdown test was conducted, and the impulse breakdown strength was 1690KV, which was extremely good. Furthermore, after disassembly, there were no tape wrinkles, tape breaks, or gap disturbances, and the tape remained in the same condition as immediately after taping. Comparative Example A resin mixture having the following composition was extruded and laminated on one side of a uniaxially stretched polypropylene sheet produced in the same manner as in Example 1 at 270°C. (a) 100 parts by weight of polypropylene resin ([η] = 2.25), (b) 10 parts by weight of polysulfone (Udel1700), (c) 2 parts by weight of dimethylpolysiloxane (50 centistokes) Subsequently, in the same manner as in Example 1 After horizontal stretching, relaxation treatment, and heat treatment, a paper-like film was wound up. The thickness of the obtained film was 110μ, with the biaxially oriented polypropylene layer being 90μ and the resin mixture layer being 20μ.
It was hot. The Young's modulus of this film is 130 in the longitudinal direction.
Kg/mm ² and 245Kg/mm ² in the width direction. The static friction coefficient and dynamic friction coefficient between the paper layer and the smooth surface of this film were 0.35 and 0.30, respectively. The R _nax value on the film side is 5μ, and the number of protrusions with a height of 1μ or more is 12/mm in the longitudinal direction and 14/mm in the width direction.
It was hot. Using this film, a model cable similar to that in Example 1 was prototyped, and a 2000D vent test was conducted twice in the opposite direction.After dismantling the cable, the occurrence of wrinkles was examined.
Wrinkles were observed throughout the layers. An impulse breakdown test was conducted on the cable after the vent test, and the impulse breakdown strength was 1480KV, a level that was clearly caused by defects in the insulation layer. As explained above with reference to the embodiments, the present invention
GF cable satisfies both high levels of dielectric breakdown strength and bending resistance, and has excellent insulating gas permeability and heat dissipation.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the gas-impregnated power cable of the present invention, and FIG. 2 is a diagram showing the relationship between partial discharge characteristics and SF ₆ gas pressure again after the long-term test in Example 4. . 1: gas flow path, 2: hollow spiral tube, 3: conductor,
4: Conductive layer, 5: Insulating layer using paper film, 6: Insulating layer, 7: Metal sheath,
8: Corrosion resistant layer.

Claims (1)

[Claims] 1. In a gas-impregnated power 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 has a biaxially stretched thickness. 40
~300μ polypropylene film as the base,
At least one side of the substrate is made of the following polymers (a), (b), (c)
The maximum roughness of the surface of the polymer mixture layer according to JIS BO 601-1976 method
A gas-impregnated power cable characterized by using a laminated film in which R _nax satisfies 0.1μ≦R _nax ≦20μ and the number of protrusions with a height of 1μ or more is 1/1 mm or more in at least one direction. (a) Polypropylene resin with 1.0≦[η]≦3.0, 100
Parts by weight, (b) One or two polymers having at least one bond selected from the following in the skeleton structure.
A mixture of more than one species whose weight average solubility parameter value is 8.5 or more, 0.5
~50 parts by weight [Formula] [Formula] [Formula] [Formula] [Formula] (c) 0.1 to 20 parts by weight of one or a mixture of two or more modified silicone oils selected from the following modified silicone oils (i) and (ii) Department, (The value of m is an integer greater than or equal to 1, and the values of x and y are 0.05≦
X/X+Y≦1) (R ₁ , R ₂ , R ₃ , and R ₄ are C ₁ to C ₂₀ alkyl groups or aralkyl groups, the value of m is 1, 2, 3, or 4, and the values of X and Y are 0≦X/X+Y ≦0.95) 2. The thickness (d ₁ ) of the polymer mixture layer of the laminated film forming the insulating layer and the thickness (d ₂ ) of the biaxially stretched polypropylene film are 0.005≦d ₁ /d ₂ ≦0.2.
The gas-impregnated power cable according to claim 1, wherein the power cable has the following relationship. 3. The gas-impregnated power cable according to claim 1, wherein the polymer mixture layer of the laminated film forming the insulating layer is at least uniaxially stretched. 4. Claims characterized in that the value of Young's modulus (unit: Kg/mm ² ) x film thickness (unit: μ) in at least one direction of the laminated film forming the insulating layer is 10 ⁴ or more Gas-impregnated power cable according to paragraph 1.