JP4900938B2 - Drop cable - Google Patents

Description

  The present invention relates to a lead-in wire or an optical drop cable (hereinafter referred to as a drop cable) that is used outdoors and drawn from an overhead wire to an attachment point at a place of demand. The present invention relates to a drop cable that prevents damage.

  A conventional protective optical transmission cable has an optical fiber core in the center, tension members spaced on both sides, and a protective coating with a major axis / minor axis ratio of 1-2 on both. V-shaped with a small gap between the protective coating and the optical fiber core, with a circular arc at the bottom of the surface of the protective coating, and a small radius at the intersection of the valley and the outer peripheral surface A concave groove is formed, and a support wire with an outer cover is provided on the outer side of the protective coating. The depth of the V-shaped concave groove is set to 1/12 to 1/1 of the minor axis of the protective coating. 7 and the radius of the arc is 1/18 to 1/8 of the short axis of the protective coating (see, for example, Patent Document 1).

  In addition, the conventional drop optical fiber cable has a notch for tearing formed on both sides of the portion where the optical fiber core wire of the sheath of the optical fiber cable body is located, and the tip thereof is in the short side direction of the sheath cross section. The straight line extending to the center of the optical fiber is disposed so as to be at a position separated by 0.6 mm or more from the center of the optical fiber core wire (see, for example, Patent Document 2).

  Further, the conventional optical drop cable has an optical fiber core, first and second strength members arranged in parallel at intervals on both sides of the optical fiber core, and a substantially rectangular cross section for covering these together. In an optical drop cable having a cable body having a jacket and a support line portion having a support line for supporting the cable body, the cable body is almost diagonally sandwiching the optical fiber core wire on the jacket surface of the cable body. First and second slit-shaped notches are provided at positions where the respective tips reach the vicinity of the optical fiber core wire (see, for example, Patent Document 3).

  Furthermore, the conventional self-supporting lead-in optical cable has an optical element portion in which a high-strength tear string is vertically attached to both ends in the width direction of an optical fiber core sandwiched by a protective tape, and these are covered with a cable sheath. The sheath of the optical element portion in the width direction of the sheath is torn with the tear string so that the sheath is divided into a front side and a back side so that the optical fiber core wire is exposed and can be taken out (for example, (See Patent Document 4).

  Moreover, the conventional tape drop cable is a tape drop cable formed by coating an optical fiber cable core with a cable jacket, and a protective wall is provided inside the cable jacket (see, for example, Patent Document 5).

Also, the conventional tape drop cable is a tape drop cable formed by coating an optical fiber cable core with a cable jacket, and an outer sheath is provided outside the cable jacket without fusing the interface with the cable jacket. (For example, refer to Patent Document 6).
JP 2006-65288 A JP 2002-328276 A JP 2006-163337 A JP 2006-113219 A JP 2006-195109 A JP 2006-195110 A

  In conventional shielded optical transmission cables, the optical fiber core can move freely in the gap, the tip of the laying tube can be detached from the optical fiber core and cannot be directly attacked, and the optical fiber core can be damaged or broken. After that, rainwater may enter the gap from the gutter remaining on the protective coating. For this reason, there has been a problem that the optical fiber core wire may cause a communication failure by absorbing and deteriorating moisture that has entered the gap. In winter, there is a problem in that the water in the gap freezes and expands, which may damage the optical fiber and cause communication failure.

  In addition, the conventional anti-light transmission cable has a shape in which the kuma-zemi is difficult to stop, and the hardness of the protective coating is 90 (HDA) or more, but the inventors of the present application have verified it with a cable having substantially the same shape and hardness. It has been found that the bearfish stops regardless of the shape of the cable, and even with a protective coating having a hardness of 90 (HDA) or higher, the oviposition tube reaches the optical fiber core, and a sufficient effect cannot be obtained. In addition, when cables with similar shapes and hardnesses were laid horizontally between adjacent trees and vertically along the trunk of the tree, in the vertical laying compared to horizontal laying, the bears lay eggs on the cable. It was found that the possibility of piercing the tube was very low, and proper evaluation was not possible. In particular, in drop cables that are actually used for communication, the drop cables are rarely laid vertically along the trunk of the tree, so that the evaluation by vertical laying of the conventional protective optical transmission cable is not necessarily appropriate. It cannot be said.

  In addition, regarding the conventional drop optical fiber cable and the optical drop cable, the inventors of the present application verified using a cable having substantially the same shape. It was found that the fiber core was reached and sufficient effects could not be obtained.

  In addition, the conventional self-supporting lead-in optical cable and tape drop cable are difficult to manufacture because it is necessary to newly add a protective tape, a protective wall, or an exterior covering as a component of the cable. There was a problem that the cost of the cable was high.

  In addition, protective coatings (sheaths, jackets, cable sheaths, cable jackets, jackets) used for conventional protective optical transmission cables (drop optical cables, optical drop cables, self-supporting pull-in optical cables, tape drop cables) Is a relatively soft material such as soft vinyl chloride resin or low density polyethylene to facilitate removal of the coated optical fiber from the protective coating. For this reason, it is easy for the bearfish to pierce the oviduct with respect to the protective coating, and since the protective coating is easily deformed, when the laying tube is pierced, the volume of the oviduct in the protective coating is reduced. A part of the corresponding protective coating protrudes toward the surface of the cable, so that a space for laying eggs can be easily formed in the protective coating. Therefore, the cable has become a suitable spawning ground for Kuma-Zemi, and there is a problem that there is a high possibility that the optical fiber core wire will be damaged.

  The present invention has been made to solve the above-described problems, and provides a drop cable having a protective coating that does not increase the number of members of the drop cable and does not allow the egg-laying tube of the bearfish to reach the core. To do.

The drop cable according to the present invention is a drop cable formed by coating a core wire with a single-layer protective coating, wherein the protective coating has a tensile elastic modulus 100% modulus of 12 to 30 MPa and a tensile strength of 15 It is made of a thermoplastic resin of an olefin resin having a Shore D hardness of HDD 50-80.

Also, in the drop cable according to the present invention, if necessary, the protective coating, a specific gravity of 0.9 to 1.15.

The drop cable according to the present invention is a drop cable formed by coating a core wire with a single-layer protective coating, wherein the protective coating has a tensile elastic modulus 100% modulus of 12 to 30 MPa and a tensile strength of 15 Due to being made of a thermoplastic resin of ˜40 MPa, even if the komazemi pierces the egg laying tube into the drop cable, the protective coating does not deform so as to expand, and a space for laying eggs is secured in the protective coating. Inability to do so can cause the oats to abandon spawning in the protective coating and abandon the puncture of the spawning tube against the drop cable.

In the drop cable according to the present invention, before Symbol protective coating, by Shore D hardness of a thermoplastic resin of olefin resin is HDD50～80, that ovipositor of cicada reaches core wire Therefore, it is possible to provide a drop cable that does not damage the core and does not cause communication failure. In addition, even if the bearfish pierces the egg laying tube into the drop cable, the protective coating does not deform so as to expand, and the egg laying tube cannot be pierced to the back, ensuring a space for egg laying in the protective coating. Inability to do so may cause the oats to abandon spawning in the protective coating and abandon the puncture of the spawning tube against the drop cable.

  Furthermore, in the drop cable according to the present invention, if necessary, the protective coating has a specific gravity of 0.9 to 1.15, so that the drop cable can be compared with a conventional protective coating having the same thickness. By reducing the weight, the drop cable is likely to vibrate when the bear swallow stops on the drop cable, and it may cause the drop cable to fly to another stable location without piercing the egg laying tube deeply. .

(First embodiment of the present invention)
FIG. 1 is a cross-sectional view showing an optical drop cable in a first embodiment for carrying out the present invention. In FIG. 1, the optical drop cable 100 in the first embodiment is formed by joining a main body portion 10 covered with a protective coating 1 and a support wire portion 20 with a bridge portion 30.

The main body 10 includes two optical fiber cores 2 covered with a protective coating 1 and two reinforcing wires 3 made of aramid fiber reinforced plastic disposed on both sides of the optical fiber core 2. It is a configuration. Further, a notch portion 11 is formed at a position opposite to the side surface on the surface of the protective coating 1 of the main body portion 10, and this notch portion 11 reduces the friction coefficient by minimizing the contact area with the inner wall of the pipe line when entering the pipe line. At the same time, appropriate flexibility of the main body 10 itself is obtained. In particular, the notch 11 can easily and reliably perform the incision work when the optical fiber core wire 2 is pulled out from the protective coating 1.
The support wire portion 20 is configured by covering a steel messenger wire 4 with the same protective coating 1 as the main body portion 10.

  Here, the thickness of the protective coating with respect to the optical fiber core wire is about 0.6 mm or more. Even in the optical drop cable 100 in the first embodiment, the protective coating 1 is formed in the optical fiber core in the main body 10. The wire 2 is coated in a radial direction with a thickness of 0.6 mm or more.

  The protective coating 1 is a thermoplastic resin such as an olefin resin, a vinyl chloride resin, or a rubber resin having a tensile modulus of 100% modulus of 12 MPa or more and a tensile strength of 15 MPa or more, as shown in Examples described later. Consists of.

  In addition, since the protective coating 1 can obtain an appropriate flexibility of the main body 10 itself and can easily and reliably perform the incision work when the optical fiber core wire 2 is pulled out from the protective coating 1, the tensile elasticity is increased. It is preferably made of a thermoplastic resin having a modulus of 100% modulus of 30 MPa or less and a tensile strength of 40 MPa or less.

  Further, it is more preferable that the protective coating 1 is made of a thermoplastic resin having the above-described characteristics and having a Shore D hardness of HDD50 or more as shown in Examples described later. Further, since the protective coating 1 can obtain an appropriate flexibility of the main body 10 itself, and when the optical fiber core wire 2 is pulled out from the protective coating 1, the incision operation can be easily and reliably performed. It is preferably made of a thermoplastic resin having a hardness of HDD80 or less.

  Further, the protective coating 1 has the above-described characteristics and is made of a thermoplastic resin having a specific gravity of 1.15 or less, thereby reducing the weight of the optical drop cable 100 compared to a conventional protective coating having the same thickness. Thus, when the bearfish stops at the optical drop cable 100, the optical drop cable 100 is likely to vibrate, and the optical drop cable 100 is allowed to fly toward another stable place without piercing the egg-laying tube deeply. It is preferable. Further, it is conceivable that the protective coating 1 is selected from thermoplastic resins having a specific gravity of 0.9 or more depending on materials that may be used.

  As described above, in the optical drop cable 100 according to the first embodiment, the material of the protective coating 1 is made of a thermoplastic resin having a tensile elastic modulus of 100% modulus and an optimum tensile strength. Even if the laying tube is pierced into the optical drop cable 100, the protective covering 1 does not deform so as to expand, and a space for laying eggs cannot be secured in the protective covering 1. It is possible to abandon the spawning into 1 and abandon the piercing of the spawning tube to the optical drop cable 100.

  Moreover, since the material of the protective coating 1 is made of a thermoplastic resin having an optimum Shore D hardness, the spawning tube of the bearfish does not reach the optical fiber core 2. No damage and no communication failure.

Further, the material of the protective coating 1 is made of a thermoplastic resin having a specific gravity in an optimal range, so that the optical drop cable 100 is reduced in weight compared to a conventional protective coating having the same thickness, so that When it stops at the drop cable 100, the optical drop cable 100 is easy to vibrate, and can be made to fly toward another stable place without piercing the egg drop tube deeply into the optical drop cable 100.
(Second embodiment of the present invention)
FIG. 2 (a) is a transverse sectional view showing a two-core optical drop cable in the second embodiment for carrying out the present invention, and FIG. 2 (b) is in the second embodiment for carrying out the present invention. 4 is a cross-sectional view showing a four-core optical drop cable, FIG. 3 is a cross-sectional view showing another optical drop cable in the second embodiment for carrying out the present invention, and FIG. 4 is a first cross-sectional view for implementing the present invention. It is a cross-sectional view showing still another optical drop cable in the second embodiment. 2 to 4, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and the description thereof is omitted.

  The second embodiment is different from the first embodiment only in that the shape of the notch portion is different from that of the first embodiment. Except for the operation and effect of the notch portion described later, the same operation and effect as the first embodiment are achieved. .

  In FIG. 2A, the optical drop cable 100 according to the second embodiment is formed by joining the main body portion 10 and the support wire portion 20 at the bridge portion 30 similarly to the first embodiment described above. On the other hand, as a different point, the notch portion 12 on the surface of the protective coating 1 has a wedge-shaped cross-sectional shape, and a notch portion center line 12a from the inlet side to the back side of the notch portion 12 connects the reinforcing wires 3 to each other. It is configured to be arranged so as to be an oblique line that is inclined by a predetermined angle with respect to the straight line and does not pass through the optical fiber core wire 2.

  The main body 10 includes two optical fiber cores 2 covered with a protective coating 1 and two reinforcing wires 3 made of aramid fiber reinforced plastic disposed on both sides of the optical fiber core 2. It is a configuration. In addition, a wedge-shaped notch 12 is formed obliquely at a rotationally symmetric position around the main body 10 on the surface of the protective coating 1 of the main body 10 so that the optical fiber core wire 2 is pulled out from the protective coating 1. In addition to the original function of easily performing the tearing operation of 1, the thin protruding piece portion of the protective coating 1 outside the notch portion 12 is bent at the time of entering the pipeline, whereby the pipeline The contact area with the inner wall and the existing cable can be made as small as possible to reduce the friction coefficient. Furthermore, since the depth direction of the notch portion 12 is deviated from the optical fiber core wire 2, damage to the core wire by insects such as cicada having the property of inserting a laying tube into such a narrow gap portion can be avoided. It will be.

The notch portion 12 is arranged such that the notch portion center line 12a is inclined by 15 ° to 45 ° with respect to the straight line connecting the reinforcement wires 3 and the reinforcement wire 3 is positioned on the extension of the notch portion center line 12a. It is preferable to do this. The opening angle of the wedge-shaped cross section of the notch portion 12 is preferably 30 ° or less. Further, when the cross-sectional shape of the main body 10 is rectangular as shown in FIG. 2, the notch 12 is arranged so that the opening of the notch 12 is located at the corner of the main body 10. It is desirable in terms of display layout and cable handling.
The support wire portion 20 is configured by covering a steel messenger wire 4 with the same protective coating 1 as the main body portion 10, as in the first embodiment.

  As described above, the optical drop cable 100 according to the second embodiment cannot secure a space in the protective covering 1 for bearfish to lay eggs, as in the first embodiment described above. In addition to the fact that the egg-laying tube does not reach the optical fiber core 2, the risk of damage to the optical fiber core wire 2 can be reduced by appropriately arranging the notch portion 12 in the main body portion 10. Durability and reliability as a cable can be improved.

  In the optical drop cable 100 according to each of the above-described embodiments, the two optical fiber cores 2 are arranged in the main body 10 in a vertically arranged manner. However, the configuration is not limited to this configuration, and FIG. ) Or the number of the optical fiber cores 2 and how to arrange them can be appropriately set within a range that can be properly accommodated in the main body 10 as shown in FIG. Further, the optical fiber core 2 is not limited to a configuration in which one or a plurality of single optical fiber cores 2 are arranged, but a bundle or tape in which a plurality of optical fiber cores 2 are integrated with a common coating. It can also be set as the structure which arrange | positions one or more sets of a shaped core wire.

  In addition, in the optical drop cable 100 according to each of the embodiments described above, the notches 11 and 12 on the surface of the protective coating 1 are provided at two locations that are rotationally symmetric about the optical fiber core wire 2, respectively. The arrangement position is not limited to this configuration, and the arrangement position may be any position around the optical fiber core wire 2 as long as the outer shell can be easily cut by the hand and the core wire can be easily taken out. In addition, the number of notch portions is not limited to two, but may be one or three or more. If the number of notch portions is increased, the flexibility of the main body 10 can be increased.

  Further, when the tool for taking out the core wire can be used at all times, or when it is desired to reduce the risk of the strength decrease due to the presence of the notch portion and the risk of the core wire damage increase as much as possible, as shown in FIG. Similar to the embodiment, the optical drop cable 100 has a structure including the main body 10 and the support wire 20 in which the optical fiber core wire 2 and the reinforcing wire 3 are covered with the protective coating 1, but has no notch portion. It can also be.

  Further, in the optical drop cable 100 according to each of the embodiments described above, the support wire portion 20 in which the messenger wire 4 is covered with the protective coating 1 is integrated with the main body portion 10 to form the optical drop cable 100. The support wire portion 20 can be separated and removed as necessary, for example, when retracted, and only the main body portion 10 can be handled by inserting a pipeline.

  Further, as shown in FIG. 4, the support fiber portion 20 is not used from the beginning, the optical fiber core wire 2 and the reinforcing wire 3 are covered with the protective coating 1, and only the main body portion 10 having the notch portion 13 on the surface is used for light. The drop cable 100 can also be configured, and when the strength in the aerial state is not so necessary, a simple structure can be used to reduce the cost, and the transition to in-pipe insertion work at the time of in-home withdrawal, The operation can be performed easily and promptly without the need for separation from the support line portion 20 and the like, and since there is no remaining portion of the bridge portion 30 after the separation, the friction resistance is reduced and the operation can be performed smoothly.

  Furthermore, in the optical drop cable 100 according to each of the above-described embodiments, the reinforcing wire 3 is arranged in two lines arranged in a straight line with the optical fiber core wire 2 and the messenger wire 4, but not limited thereto, Depending on the use of the cable and the installation environment, the arrangement position and the number of the reinforcement wires 3 with respect to the core wire may be appropriately changed.

  In each of the above-described embodiments, the optical drop cable 100 in which the core wire is the optical fiber core wire 2 has been described. However, for the lead-in wire having a metal conductor such as a telephone wire as the core wire, There are cases where rainwater enters into the lead-in line, and the metal conductor corrodes and leads to a communication failure due to disconnection. For this reason, the same operation effect can be produced by covering the core wire of the lead-in wire with the protective coating 1 having the same characteristics as the optical drop cable 100 according to each of the above-described embodiments.

Next, the operational effects of the optical drop cable 100 according to each of the embodiments described above will be described by showing the results of verification tests using the examples and comparative examples according to the present invention.
FIG. 5 is an explanatory diagram showing the characteristics of the examples and comparative examples, FIG. 6 is an explanatory diagram showing the relationship between the tensile modulus 100% modulus and the tensile strength and egg laying, and FIG. FIG. 8 is an explanatory diagram showing the calculation result of the puncture wound by the laying tube.

  In FIG. 5, Examples 1 to 6 are optical drop cables 100 made of the protective coating 1 having the characteristics that the modulus of 100% tensile modulus is 12 MPa or more and the tensile strength is 15 MPa or more. In particular, Example 1 and Example 2 are optical drop cables 100 made of the protective coating 1 having a characteristic that the Shore D hardness is equal to or higher than the HDD 50.

  First, in the cross section, the width is about 2 mm or 3 mm, the height is about 5 mm or 6 mm, and the structure shown in FIG. 3 protects Examples 1 to 6 or Comparative Examples 1 to 5 An optical drop cable applied as each of the coverings 1 was made as a prototype, and a verification test was performed in the field.

  In the field verification test, a prototype optical drop cable was laid horizontally between adjacent trees with a laying length of 13 m, and two vertically installed laying lengths of 2 m along the trunk of the tree. In Fig. 4, the presence or absence of egg laying by the bear zest in the optical drop cable was confirmed. Moreover, the depth of the stab wound by an oviduct was measured. The results are shown in FIGS.

6 and 7, the black circles (●) indicate the respective examples, the white circles (◯) indicate the respective comparative examples, and the round numerals (1) to (11)) indicate the respective examples and the respective examples in FIG. 5. Each corresponds to a circled number in the comparative example.

  As shown in FIG. 6, the optical drop cable 100 is a region surrounded by a two-dot chain line, from the protective coating 1 having the characteristics that the modulus of 100% tensile modulus is 12 MPa or more and the tensile strength is 15 MPa or more. By this, it can be seen that egg laying by the bearfish can be prevented.

  In particular, as shown in FIG. 7, the optical drop cable 100 in which the protective coating 1 of Example 6 is used is capable of spawning by the komazemi even though the depth of puncture by the laying tube reaches 1.7 mm. There was no. This is because the deformation that causes the protective coating 1 to expand does not occur, and a space for laying eggs cannot be secured in the protective coating 1, so that the bearfish gave up the egg-laying into the protective coating 1. It is considered a thing.

  However, the depth of the puncture wound by the laying tube reaches 1.7 mm. As described above, the protective coating 1 in the optical drop cable 100 according to the present invention has an optical fiber core in the main body 10. For example, in the optical drop cable 100 covered with the protective coating 1 having a thickness of 0.6 mm which is the minimum value by being covered with a thickness of 0.6 mm or more in the radial direction of the wire 2, the egg-laying tube May reach the optical fiber core 2.

  Therefore, the HDD 50 is calculated as the Shore D hardness corresponding to the depth of puncture by the laying tube from the approximate curve shown in FIG. The lower limit value of Shore D hardness at which the oviposition tube of the bearfish does not reach the optical fiber core wire 2 was specified.

  Next, the outer dimensions are about 2 mm or 3 mm in width and about 5 mm or 6 mm in height in the cross section, and each structure shown in FIG. 2 (a), FIG. 2 (b) or FIG. Alternatively, an optical drop cable to which Comparative Example 2 was applied as the protective coating 1 was experimentally manufactured, and a verification test was performed in the field.

  In Example 1 or Comparative Example 2, the Shore A hardness is equivalent to HDA95, but the durometer type is used as described in Japanese Industrial Standards JIS K 7215 (Plastic Durometer Hardness Test Method). In the case of selection, when the type A durometer is 90 or more, it is desirable to use the type D durometer, and the Shore D hardness is also measured. In this Shore D hardness, Example 1 and Comparative Example 2 are significantly different.

  In the field verification test, a prototype optical drop cable was laid horizontally between adjacent trees with a laying length of 13 m, and two vertically installed laying lengths of 2 m along the trunk of the tree. In Fig. 1, the number of puncture wounds caused by the oviposition tube of the bearfish was counted for each component of the optical drop cable. Moreover, the presence or absence of the stab wound reaching the core and the presence or absence of spawning in the optical drop cable were confirmed.

  As shown in FIG. 8, in the difference in the material of the protective coating, in Comparative Example 2, the number of punctures caused by the laying tube is 2.4 times or more compared to Example 1 (5 in the difference in presence or absence of the notch portion). It is understood that the number is much higher. Moreover, when the depth of the puncture was observed, Comparative Example 2 reached the optical fiber core, but Example 1 did not reach the optical fiber core at all.

  Here, the bearfish has the habit of laying eggs in the dead branch, and the optical drop cable and the dead branch are indistinguishable, and the egg drop tube is inserted into the optical drop cable. On the other hand, Example 1 was unable to pierce the egg-laying tube deep inside the protective coating 1, and recognized that the pierced optical drop cable was not a dead branch. Compared with Comparative Example 2, it is considered that the number of puncture wounds by the oviduct was extremely reduced.

  Further, it can be seen that there is a stab wound regardless of the support line portion, the bridge portion, the main body portion and the notch portion in the difference in the cross-sectional shape of the optical drop cable. That is, it can be seen that the notch portion does not play a role as a guide when piercing the laying tube. However, the notch part and the bridge part were deeper than the support line part and the main body part. For this reason, if it is the notch part 12 which has the structure arrange | positioned so that the notch part centerline 12a in the 2nd Embodiment mentioned above may become the diagonal line | wire which does not pass the optical fiber core wire 2, it is effective. it is conceivable that.

  Further, in the difference in the laying state, the horizontal laying had much more punctures by the laying tube than the vertical laying, and the stabs were concentrated near the part in contact with the tree. In particular, when vertical laying is performed, there is a high possibility that the egg-laying tube will be pierced into the trunk of the tree, and the optical drop cable will not be pierced.

BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional view which shows the optical drop cable in 1st Embodiment for implementing this invention. It is a cross-sectional view which shows the optical drop cable in 2nd Embodiment for implementing this invention, (a) is a cross-sectional view which shows a two-core optical drop cable, (b) is four-core light It is a cross-sectional view showing a drop cable. It is a cross-sectional view which shows the other optical drop cable in 2nd Embodiment for implementing this invention. It is a cross-sectional view which shows the further another optical drop cable in 2nd Embodiment for implementing this invention. It is explanatory drawing which showed the characteristic of the Example and the comparative example. It is explanatory drawing which showed the relationship between a tensile elasticity modulus 100% modulus and tensile strength, and egg-laying. It is explanatory drawing which showed the relationship between Shore D hardness and the depth of the stab wound by an oviduct. It is explanatory drawing which showed the calculation result of the stab wound by an oviduct.

Explanation of symbols

1 Protective coating
2 Optical fiber core
3 Reinforcing wire
4 Message wire 10 Body portion 11, 12, 13 Notch portion 12a Notch portion center line 20 Support line portion 30 Bridge portion 100 Optical drop cable

Claims (2)

A drop cable made by coating a core wire with a single layer of protective coating,
The protective coating is composed of an olefin-based thermoplastic resin having a tensile modulus of 100% modulus of 12 to 30 MPa, a tensile strength of 15 to 40 MPa, and a Shore D hardness of HDD 50 to 80. Drop cable. The drop cable according to claim 1,
The protective cover has a specific gravity of 0.9 to 1.15 .

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