JP5805960B2 - Flame retardant ant cable - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a flame-retardant ant cable having flame retardancy, and more particularly to a cable having ant-preventive properties for preventing white ants from causing damage (ant damage) and having flame retardancy. In addition, although the description content of this invention has described the case where it applies to a power cable, this invention is applicable also to a communication cable.

  In general, as shown in FIG. 1, the power cable 1 is directly buried in the ground, and is housed in a container such as a conduit 30 or a concrete trough and buried in the ground (pipe section 3). . On the other hand, white ants are widely distributed and inhabited on the earth, and ant damage to power cables has been reported in Japan.

  As a conventional method for preventing the power cable from the ant damage, a power cable obtained by adding an ant protection agent to a polyvinyl chloride anticorrosion layer (vinyl anticorrosion layer) or a plastic sheath has been widely used. Here, the anticorrosion layer is as defined in JEC3402-2000, when used as a cable sheath including a metal sheath, and the plastic sheath is as defined in JEC3403-2000 as a metal sheath. These terms are used when the cable is used as an exterior of a cable that does not contain, but since the properties required as protective materials are the same, the terms `` corrosion protection layer '' and `` plastic sheath '' are unified. “Anti-corrosion layer”.

  However, since some ant protection agents are prohibited from the viewpoint of protecting the global environment, recently, as an external anticorrosion layer, nylon is used on the vinyl anticorrosion layer, which is an internal anticorrosion layer that does not contain an ant protection agent. Nylon ant-proof cables with a structure coated with (registered trademark) are widely used.

  On the other hand, in Article 47, Paragraph 2 of “Ministerial Ordinance (Electrical) for Establishing Technical Standards for Electrical Equipment” (see Non-Patent Document 1), “ Must be taken. "

  In addition, in Section 5, Article 134, Section 3 of "Interpretation of technical standards for electrical equipment (electrical technology)" (see Non-Patent Document 2), (Omitted) Fireproof measures were applied to underground cables, and (Omitted). "

  Here, the term “flameproof measures” means that “use an underground cable having a nonflammable or self-extinguishing flame-retardant coating” or “nonflammable or self-extinguishing property” in Article 134, paragraph 7 of the electric technology. Covering underground power transmission lines with certain flame retardant flame spread prevention tapes, flame spread prevention sheets, flame spread prevention paints, and the like. "

  In addition, the self-extinguishing flame retardancy is defined as “compliance with the flame resistance test of Annex 1 of the Ministerial Ordinance Attached Table 1 which defines technical standards for electrical appliances” It has the same or better performance. ”

Japanese Utility Model Publication No. 6-36142 Japanese Patent Laid-Open No. 3-15114 JP-A-5-174635 Japanese Patent Laid-Open No. 9-139117

Ministerial Ordinance for Establishing Technical Standards for Electrical Equipment Interpretation of technical standards for electrical equipment

  However, for example, in the cable 7 having the anticorrosion layer 76 as shown in FIG. 7, the vinyl anticorrosion layer conforms to the flame resistance test as the anticorrosion layer 76, but the vinyl anticorrosion layer as shown in FIG. When a nylon ant protection layer is coated on top (corrosion protection layer 86, ant protection layer 87), the nylon is a material that does not conform to the flame resistance test.

  Further, as a standard and standard of flame retardance that is more severe than the above-mentioned flame proof measures, IEEE std. There is a test of 383-1974 (flame retardant test), and in this fire retardant test, "do not burn to the upper end" is required. The “upper end” refers to a position 1800 mm long from the burner height of the test cable on which the burner port is placed. Therefore, if the combustion is 1800 mm or less, the test passes.

  Therefore, since the nylon ant cable covers nylon on the vinyl anticorrosive layer, the nylon itself is an expensive material, and the price is higher than that of a normal vinyl anticorrosive cable. In addition, when a part of the nylon antproof cable 1 laid on the pipe line 30 as shown in FIG. 1 is laid on the “space where work can be performed” such as the dark part 4, the nylon antproof cable 1 It is necessary to wrap the flame spread prevention tape around, and the material cost and construction cost of the flame spread prevention tape are added, which further increases the price. Furthermore, since it is necessary to wrap the fire spread prevention tape after laying the cable, there is a problem that the construction period is prolonged.

  As a means for solving this, there is a cable 9 having an internal anticorrosion layer 96, an anticorrosive layer 97 and an external anticorrosion layer 98 as shown in FIG. A flame proof ant cable (hereinafter referred to as “triple sheath structure”) having a structure in which a nylon ant protection layer is provided and a vinyl protection layer is further formed as an external protection layer 98 thereon. Although this flame proof cable can be omitted, the flame proof cable has a triple sheath structure, so it is more expensive than nylon ant cable and has a larger cable outer diameter. There are problems such as increasing the cable weight and restricting the applicable pipeline for the cable.

  Further, as a conventional flame-retardant ant cable, there is a cable composed of two ant-proof layers having an anti-corrosion layer 86 of an internal anti-corrosion layer and an anti-corrosion layer 87 of an external anti-corrosion layer shown in FIG. Each of the two ant-proof layers is a combination of flame retardant materials made of flame retardant polyvinyl chloride, flame retardant nylon, or the like, and having an oxygen index of 27 or more. In order to realize this flame retardant property, it has been considered that each material of the two ant protection layers has a flame retardant property. However, a flame retardant material having flame retardant properties having an oxygen index of 27 or more has a problem that the material cost is high and the price of the cable is high (see, for example, Patent Document 1 and Patent Document 2).

  Further, as a conventional flame-retardant ant cable, a coating in which a polypropylene in which a high molecular weight silicone polymer is dispersed at a high concentration of 20% or more instead of nylon 11 or 12 is coated as an anticorrosion layer, and nylon 6 or 66 (polyamide) There is a resin composition in which 90 to 50% by weight of the resin is mixed with polypropylene and coated as an anticorrosion layer. However, these polypropylene anticorrosive cables are made of ultra-molecular weight silicone polymer at a high concentration of 20% or more, so that the cable becomes expensive and sufficient flame retardant performance cannot be obtained. And nylon 6 or 66 (polyamide resin) in which 90 to 50% by weight is ordinary nylon, there is a problem that sufficient flame retardancy cannot be secured (for example, Patent Document 3, Patent Document) 4).

  Accordingly, an object of the present invention is to provide a flame-retardant ant cable that is less expensive than conventional nylon flame-retardant ant cables, is suitable for a flame-retardant test, and has ant-proof properties.

  In order to achieve the above object, the present invention provides a flame retardant ant cable having the following flame retardant and ant proof properties.

[1] An internal anticorrosion layer consisting of a flame retardant polyvinyl chloride having an oxygen index of 30 or more, which is an extruded resin anticorrosive layer or an extruded resin sheath;
Consists oxygen index 2 0 or One Hardness (Shore D) 60 or more flame retardant polypropylene, having an external anticorrosion layer covering the inner anticorrosion layer by a thickness of 50% or less of the thickness of the inner anti-corrosion layer Flame retardant ant cable featuring

  That is, the present invention provides a flame retardant material having an oxygen index of 30 or more having flame retardancy as an internal corrosion protection layer, and an oxygen index having flame retardance characteristics compatible with an ant protection property instead of a nylon ant protection layer as an external corrosion protection layer. It is composed of a flame retardant polypropylene having a hardness of 20 or more and a hardness (Shore D) of 60 or more, and the thickness of the flame retardant polypropylene is 50% or less (however, the minimum thickness is 0.5 mm) with respect to the internal anticorrosion layer. is there. Here, the adaptable flame retardant characteristic is that the cable in which the flame retardant layer is formed of only one layer and is coated with the flame retardant layer as an anticorrosion layer is “the interpretation of technical standards of electrical equipment”. Flame retardancy having performance equivalent to or better than the flame resistance test in Article 14 and passing the JIS C3005 4.26b slope test.

  The oxygen index is a measured value measured according to JIS K7201 “Method for Combustion Test of Polymer Material Using Oxygen Index Method”, and is an index that defines the combustibility of rubber, plastic, fiber, etc., which are polymer materials. It is. In general, a flame retardant polyvinyl chloride material having an oxygen index of 26 or more is selected for the vinyl anticorrosive layer of the power cable. Polypropylene itself generally has an oxygen index of less than 20, but by adding a flame retardant, a flame retardance value of 20 or more can be obtained.

  Then, the present inventors have provided a polypropylene layer having a flame retardancy imparted to the outside of the cable in which a flame retardant internal anticorrosion layer having a thickness of 4.0 mm or more and an oxygen index of 30 or more is present. When the coating was thicker than 0 mm, the polypropylene itself burned and failed the flame retardancy test, but when it was coated to a thickness of 2.0 mm or less, it was found to pass the flame retardancy test.

  Moreover, if the coating thickness of a polypropylene layer is 0.5 mm or more similarly to the coating thickness of a nylon ant-proofing layer, it has confirmed by the embedded ant-proofing test that it has ant-proofing performance. Therefore, the coating thickness is set to a minimum of 0.5 mm and a maximum of 2.0 mm, that is, an external anticorrosion layer having a thickness of 50% or less and a minimum thickness of 0.5 mm is provided with respect to the thickness of the internal anticorrosion layer. It is possible to provide a flameproof ant cable that passes the flame retardancy test.

  According to the present invention, it is possible to realize a flame retardant ant cable that is less expensive than conventional nylon flame retardant ant cables, conforms to a flame retardant test, and has ant proof properties.

FIG. 1 is a cross-sectional view for explaining a state in which a power cable is laid in the underground. FIG. 2 is a cross-sectional view showing an example of the configuration of the flame-retardant ant cable according to the embodiment of the present invention. FIG. 3 is a cross-sectional view showing another example of the configuration of the flame-retardant ant cable according to the embodiment of the present invention. 4 (a) is a perspective view showing the configuration of the sheet sample, FIG. 4 (b) is a table showing the result of the ant protection test on the sheet sample, and FIG. 4 (c) is a result of the ant protection test on the flame retardant ant protection cable sample. It is a table | surface which shows. FIGS. 5A and 5B are tables showing the results of the flame resistance test and the flame resistance test of the flame retardant ant cable samples. FIG. 6 is a table showing an example of the relationship between the cable outer diameter and the applied pipe inner diameter. FIG. 7 is a cross-sectional view showing an example of a configuration of a cable having a conventional vinyl anticorrosion layer. FIG. 8 is a cross-sectional view showing an example of the configuration of a conventional flame-proof ant cable having a nylon ant-proof layer. FIG. 9 is a cross-sectional view showing an example of the configuration of a flame retardant ant cable having a conventional triple sheath structure.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 2 is a cross-sectional view showing an example of the configuration of the flame-retardant ant cable according to the embodiment of the present invention.

  The cable 1A is an example in which a coating (metal coating) made of metal such as corrugated aluminum (corrugated aluminum) is not provided, and includes a conductor 100, an internal semiconductor layer 101, an insulator 102, and an external semiconductor layer. 103, a shielding layer 104 such as an annealed copper wire, and a holding tape 105 are sequentially provided, an internal anticorrosion layer 106 such as flame retardant polyvinyl chloride (flame retardant PVC), and a flame retardant polypropylene having flame proof properties (flame retardant). PP) external anticorrosion layer 107 and the outer periphery thereof.

  FIG. 3 is a cross-sectional view showing another example of the configuration of the flame-retardant ant cable according to the embodiment of the present invention.

  The cable 1B is another example of an OF (oil-filled) cable provided with a metal sheath, and is divided into an oil passage 110, a galvanized steel strip spiral 111, a conductor 112 made of six annealed copper wires, and the conductor 112. Insulating paper 113, binder 114 made of metal tape and kraft paper, carbon paper 115, insulator 116 made of insulating paper, carbon paper 117, and shielding tape 118 made of metal tape and carbon paper. Provided sequentially, copper wire woven cloth tape 119, corrugated aluminum 120 and anticorrosion paint 121 are provided on the outer periphery thereof, internal anticorrosion layer 122 such as flame retardant PVC on the outermost periphery, and it is difficult to have ant-proof properties. This is a structure in which an external anticorrosion layer 123 of fuel PP is provided. The structure of the anticorrosion layer can be applied to other than the OF cable.

(Results of ant protection test)
4 (a) is a perspective view showing the configuration of the sheet sample, FIG. 4 (b) is a table showing the result of the ant protection test on the sheet sample, and FIG. 4 (c) is a result of the ant protection test on the flame retardant ant protection cable sample. It is a table | surface which shows.

  As shown in FIG. 4A, the sheet sample has a thickness of 1 mm, a width of 120 mm, and a depth of 100 mm, and the degree of ant damage is the ant damage length a in the width direction (the ant damage length depends on the ratio of the entire circumference). Defined) and the ant damage reach distance b in the depth direction.

  The result of the ant-proofing test in the sheet sample according to the ant-proofing material is as shown in FIG. 4 (b), and polypropyne (PP) that does not impart flame retardancy compared to the conventional nylon 12 reach distance of 1.0 mm. The reaching distance was 0.5 mm, and the reaching distance of flame retardant polypropylene (flame retardant PP) was 1.0 mm. In the determination column, “Nylon 12”, which is the current ant-proof material, is used as a reference, “◯” indicates that the characteristics are superior to this reference value, and “X” indicates that the characteristics are inferior. Note that PVC is flame retardant PVC having an oxygen index of 30, HDPE is high density polyethylene, flame retardant PP is flame retardant PP having an oxygen index of 20 and hardness (Shore D) 60, and PP is a hardness that does not impart flame retardancy (Shore D). ) 60 PP.

Further, using a 77 KV CV single-core 100 mm ² flame-retardant ant cable having the structure shown in FIG. 2, a flame-retardant PP having an oxygen index of 20 mm and a hardness (Shore D) of 60 with a thickness of only the inner anticorrosion layer. A flame retardant PVC having an anticorrosion layer and an inner anticorrosion layer having a thickness of 4.0 mm and an oxygen index of 30; and an outer anticorrosion layer covering the outer periphery of the flame retardant PVC having an oxygen index of 20 mm having a thickness of 1.0 mm The ant-proof test was conducted using a flame retardant PP having a hardness (Shore D) of 60. The result of the buried ant protection test with this cable sample is as shown in FIG. 4C. When the flame retardant PP of the single anticorrosion layer is used as the sheath, and the flame retardant PVC and the flame retardant PP of the double anticorrosion layer. In both cases where the sheath was formed, good ant protection performance was obtained without being damaged by the white ants.

This buried ant protection test method is a method of preparing a sample cable having a length of 60 cm and burying it with a bait tree in a test site where many white ants live.
And the judgment standard of the ant damage (corrosion damage) is the presence or absence of the damage damage of the said cable sample visually.

  From these results, it was found that even PP that does not impart flame retardancy has ant-proofing performance, so if the coating thickness is 0.5 mm or more, it has ant-proofing performance equivalent to or higher than that of conventional nylon 12. .

(Results of flame resistance test and flame resistance test)
Next, FIG. 5 (a) is a 77KV CV single core 100mm2 flame-retardant ant cable used in the above-mentioned ant protection test of FIG. 4 (c), with an outer diameter of 50mm, and FIG. 5 (b). Using a flame resistant ant cable of 22 KV CV single core 100 mm ² with an outer diameter of 35 mm, the flame retardant PVC having an inner anticorrosive layer thickness of 4.0 mm and an oxygen index of 30 was coated on the outer periphery of the flame retardant PVC. A flame retardant test and a flame retardant test were performed using a flame retardant PP having an oxygen index of 20 and a hardness (Shore D) of 60 of the external anticorrosion layer, and the thickness was changed to 1 mm, 2 mm and 3 mm. It is a table | surface which shows the test result of the flame resistance test of this cable sample, and a flame retardance test.

In addition, each method and criterion of the said flame resistance test and a flame retardance test are as follows.
JIS C3005 4.26b Flame Resistance Test Method and Judgment Criteria Test method: The sample is supported with an inclination of about 60 degrees with respect to the horizontal, and the tip of the reducing flame is about 20 mm from the lower end of the sample within 30 seconds. Apply until it burns, gently remove the flame, and then examine the degree of burning of the sample.
Judgment standard: It disappears naturally within 60 seconds.
IEEE std. 383-1974 Flame Retardancy Test Method and Judgment Criteria Test Method: Lay out the number of wires with a laying width of 150 mm at intervals of 1/2 the cable outer diameter on a ladder-like vertically installed tray. The cable is burned for 20 minutes with a defined burner from below.
Criteria: Do not burn to the top.

  As a result of carrying out the flame resistance test and the flame retardancy test, when the flame retardant PP of the single anticorrosion layer is used as the sheath, the flame retardancy test of the fire retardance level 101 (test of IEEE std. 383-1974) However, it passed the flame resistance test of the flame retardance level (gradient test of JIS C3005 4.26b) as defined in Article 134, paragraph 14 of the electric technology. Moreover, when the flame retardant PVC and the flame retardant PP of the double anticorrosive layer were used as the sheath, both the flame resistance test and the flame resistance test were passed.

Here, in general, in the flame resistance test of the flame retardance level (inclination test of JIS C3005 4.26b) specified in Article 134, paragraph 14 of Dengeki, it is known that the smaller the cable outer diameter, the easier it becomes to burn. It has been. Therefore, in order to conduct a flame retardancy test that can be determined even with a cable having a small outer diameter, it is difficult to use a flame resistant ant cable of 22 kV CV single core 100 mm ² (conductor cross-sectional area) thinner than the cable of FIG. A flame retardance test was performed with a thickness of 1 mm, 2 mm, and 3 mm of the PP, and the results are shown in FIG.

  As a result of conducting the flame retardancy test, the flame retardant PP with a thickness of 1 mm has a burnout length of 76 cm with respect to a total burn length of 180 cm (1800 mm), and the thickness of 2 mm with a burnout length of 78 cm. Satisfied and passed. This result is the result of IEEE std., Which is the three most severe grades of flame retardant levels specified in JEC3402 and JEC3403. The condition of 383-1974, that is, the condition that the combustion length is 1200 mm or less from the burner port is sufficiently satisfied. The flame retardant PP having a thickness of 3 mm was completely burned.

(Effect of embodiment)
According to the present embodiment, the following effects are obtained.
1. A flame-retardant ant cable comprising a double anticorrosive layer (sheath) was obtained at a lower cost than conventional nylon flame-retardant ant cables.
2. It is possible to provide a flame-proof ant cable that is friendly to or considered the global environment.
3. Flame retardant that passed the flame resistance test specified by the ministerial ordinance that establishes technical standards related to electrical equipment and also passed the flame resistance test of the fire forecast 101 (flame level of IEEE std. 383-1974) An ant cable was obtained.
4). A combination of a flame retardant PVC with an oxygen index of 30 and a flame retardant PP having an oxygen index of 20 and a hardness (Shore D) of 60, and the thickness of the flame retardant PP is 2 mm, which is 50% of the flame retardant PVC thickness of 4 mm. The cable which has the ant-proofing property which consists of, and a flame retardance was obtained.

5. By applying the flame-retardant ant-proof cable (1A, 1B) of the present invention to underground cable passages that have been constructed by wrapping a conventional fireproof tape around a conventional nylon ant-proof cable, the construction cost of the track is reduced and the construction period is shortened. Can be planned. In addition, the construction cost of the line can be reduced for the line of the conventional flameproof ant proof cable (triple sheath structure).
6). Further, since the outer diameter of the cable is reduced, as shown in FIG. 6, the present invention is applied to an underground cable path in which a conventional flame-proof ant cable (triple sheath structure) cannot be applied due to restrictions such as a pipe diameter. The flame retardant ant cable (1A, 1B) can be applied. In addition, the cable of FIG. 6 represents the relationship between the cable outer diameter for each size (cable conductor cross-sectional area) and the applicable pipe inner diameter in the case of 66KV CVT (three-core cable). In addition, in the case of (cable outer diameter) <(pipe inner diameter × 0.85), “○” indicating that it is applicable (Electrical Cooperative Research Vol. 61 No. 1 “Construction Technology in CV Cable Line”) Current status and future prospects ”).

In addition, this invention is not limited to the said embodiment, A various deformation | transformation is possible within the range which does not deviate from the summary of invention. For example, it can be applied as an anticorrosion layer of a flame retardant ant cable having a metal sheath such as aluminum, lead, and stainless steel.
The present invention also provides a flame-retardant ant-proof cable having the following flame-retardant and ant-proof properties.
[1] An internal anticorrosion layer which is an extruded resin anticorrosive layer or an extruded resin sheath having an oxygen index of 30 or more;
An external anticorrosion layer made of polypropylene having an oxygen index of 20 or more and a hardness (Shore D) of 60 or more, and covering the internal anticorrosion layer with a thickness of 50% or less of the thickness of the internal anticorrosion layer. Fireproof ant cable to fire.
[2] The flame-retardant ant cable according to [1], wherein the internal anticorrosion layer is flame-retardant polyvinyl chloride.

DESCRIPTION OF SYMBOLS 1A, 1B Cable 3 Pipe part 4 Dark part 7, 8, 9 Cable 30 Pipe 100 Conductor 101 Inner semiconductor layer 102 Insulator 103 Outer semiconductor layer 104 Shielding layer 105 Holding tape 106 Inner anticorrosion layer 107 External anticorrosion layer 110 Oil passage 111 Galvanized steel strip spiral 112 Conductor 113 Insulating paper 114 Binder 115 Carbon paper 116 Insulator 117 Carbon paper 118 Shielding tape 119 Flow line woven cloth tape 120 Corrugated aluminum 121 Anticorrosion paint 122 Internal anticorrosion layer 123 External anticorrosion layer

Claims (1)

An internal anticorrosion layer consisting of a flame retardant polyvinyl chloride having an oxygen index of 30 or more, which is an extruded resin anticorrosive layer or an extruded resin sheath;
Consists oxygen index 2 0 or One Hardness (Shore D) 60 or more flame retardant polypropylene, having an external anticorrosion layer covering the inner anticorrosion layer by a thickness of 50% or less of the thickness of the inner anti-corrosion layer Flame retardant ant cable featuring

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