JP2010243755A - Optical fiber cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical fiber cable which suppresses piercing by a cicada, has flame retardancy and facilitates the tearing of a jacket as well. <P>SOLUTION: In the optical fiber cable 1, a body part 2 and a support line part 3 are connected through an easy-to-cut neck part 4. In the body part 2, tension members 6 are disposed on both sides of a coated optical fiber 5 and are covered altogether by the jacket 7, and notches 8 for tearing the jacket are provided on both side faces 7a. The support line part 3 is disposed on an extension connecting the centers of the tension members 6 and the coated optical fiber 5. The jacket is molded with a flame-retardant resin, and the bottom part of the notch 8 is molded with a resin layer harder than the jacket 7. As a hard resin, a polyolefin-based resin is turned to a base resin, and the material having Shore D hardness of ≥50 and breaking strength of ≥14 MPa is used. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical fiber cable that includes a main body portion and a support wire portion, and the main body portion includes an optical fiber core wire and a tension member that are arranged in parallel and are integrally covered with a jacket.

  With the spread of information communication and the like such as the Internet, construction of an optical network is progressing in order to cope with bidirectional communication and large-capacity communication in addition to increasing the communication speed and the amount of information. In this optical network, a FTTH (Fiber To The Home) service has been started to provide a high-speed communication service by directly connecting a communication carrier and each home with an optical fiber. As a result, there is an increasing demand for drop optical cables that are used for drawing optical cables into the home, and aggregate optical cables in which a plurality of optical cables are aggregated.

  These optical fiber cables generally have a tension member embedded in the cable jacket in parallel with the optical fiber core to increase the tensile strength of the cable, and V-shaped notches are provided on both sides of the jacket. Thus, the outer cover is cut into two and the inner optical fiber core wire is taken out to form a terminal and the like.

  In recent years, a problem has frequently arisen with this type of optical fiber cable in that a spear pierces an egg-laying tube into the jacket of the cable, damages the inner optical fiber core, or lays an egg in the jacket. It is presumed that the drop optical cable was recognized as an object that can easily be laid by the cocoon, but as a countermeasure against this cocoon, the laying tube has a hardness that prevents the laying tube from piercing between the optical fiber core and the notch. Various optical cables have been proposed in which a protective body is arranged or the position and direction of the notch are changed so that the spawning tube of the moth does not pierce the optical fiber core.

However, there are cases in which the spawning tube of the moth is also inserted from a portion other than the notch, and the structural correspondence is insufficient. For example, as disclosed in Patent Document 1, the entire outer envelope is hard. Using a resin (tensile strength of 15 to 40 MPa, Shore D hardness of 50 to 80), the outer cover of the bear laying tube is prevented from being pierced by 0.6 mm or more.
In Patent Document 2, the outer side of an optical fiber arranged in a sheath (outer jacket) is covered with a reinforcing layer made of a resin having a Shore D hardness of 50 or more and a thickness of 0.3 mm or more. By doing so, the invasion of the spider's oviduct is blocked.
Patent Document 3 discloses a method of forming a protective body made of a hard resin (nylon) by molding at the same time as molding of the jacket.

JP 2008-129062 A JP 2009-25425 A JP 2008-65238 A

  As in Patent Document 1, it is possible to expect the effect of measures against wrinkles by making the entire jacket covering the optical fiber core wire hard. However, by making the jacket hard, there is a problem that it becomes difficult to remove the jacket by forming a cable end or the like. Usually, a notch on both sides of the jacket is cut about 10 mm from the end of the cable with a tool such as a nipper to make a tear start, and then the jacket is torn about 100 mm by hand. Is hard and requires labor to tear. In addition, since a large force is required for tearing, as a result, it may tear to a large extent exceeding a predetermined tear amount, for example, 100 mm (becomes NG), which is a work requiring skill.

  Further, in Patent Documents 2 and 3, two removal operations, that is, tearing the sheath covering the whole and removing the reinforcing layer are required. Although it is possible to remove the sheath and the reinforcing layer at the same time, complete integration is difficult because the resin materials of the sheath and the reinforcing layer are different. Even if the sheath and the reinforcing layer are bonded and integrated, it is necessary to make the coating of the optical fiber strands non-adhering. Therefore, the range of material selection for the optical fiber strand coating and the reinforcing layer is narrowed, and the cost is high. There is a problem that it will be.

  Further, with the expansion of the application environment of optical fiber cables, those having non-halogen flame retardancy are required. In order to impart flame retardancy to the outer jacket, a flame retardant is usually added. However, when a large amount of this additive is contained, there is a problem that the strength becomes brittle and the hardness decreases. Patent Document 3 discloses that flame retardant polyethylene is used for the outer cover, but it is a structure in which a protective body (nylon) is embedded in the outer cover, and the protective body must be removed as described above. There is a problem of complexity and cost.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide an optical fiber cable that suppresses piercing of a heel and has flame retardancy and can easily tear an outer jacket.

In the optical fiber cable according to the present invention, the main body portion and the support wire portion are connected via a neck portion that can be easily cut, and the main body portion is provided with tension members on both sides of the optical fiber core wire and is collectively covered with a jacket. In addition, notches for jacket tearing are provided on both sides, and the support wire portion is arranged on an extension line connecting the center of the tension member and the optical fiber core, and the jacket is formed of a flame-retardant resin. The bottom of the notch is formed of a resin layer harder than the outer cover.
As the hard resin, those having a polyolefin resin as a base resin and having a Shore D hardness of 50 or more and a breaking strength of 14 MPa or more are used, and more preferably, a Shore D hardness of 63 or more and a breaking strength is used. The thing of 22 Mpa or more is used.

  According to the present invention described above, the bottom of the notch is formed of a hard resin, effectively preventing damage to the optical fiber due to piercing of the spawning tube of the spider, and generally provided with flame retardancy, It may be possible to tear the jacket tear notch by hand.

It is a figure explaining the outline of the optical fiber cable by this invention. It is a figure explaining the jacket material of the optical fiber cable by this invention. It is a figure explaining an example of the manufacturing method of the optical fiber cable by this invention.

The outline of the optical fiber cable of the present invention will be described with reference to FIG. In the figure, 1 is an optical fiber cable, 2 is a main body part, 3 is a support line part, 4 is a neck part, 5 is an optical fiber core wire, 6 is a tension member, 7 is a jacket, 7a is a side surface of the jacket, 8 is A notch, 9 is a steel wire, and 10 is a hard resin layer.
An optical fiber cable 1 according to the present invention is formed in a self-supporting structure in which a main body portion 2 and a support wire portion 3 are connected by a narrow neck portion 4 that can be easily cut.

  The main body 2 has an optical fiber core 5 disposed at the center, tension members (also referred to as strength members) 6 disposed on both sides thereof, and a body 7 that is integrally covered with a jacket 7 (also referred to as a sheath). The support wire portion 3 is a steel wire 9 (outside diameter of about 1.2 mm) made of a single core wire or a stranded wire, and is provided on an extension line of the line Y connecting the optical fiber core wire 5 and the center of the tension member 6. . The steel wire 9 of the support wire portion 3 is connected to the main body portion 2 via the neck portion 4 which is easy to cut, and is covered by extrusion molding with the same resin material at the time of forming the outer cover 7 of the main body portion 2.

  The optical fiber core 5 in the present invention is a glass fiber having a standard outer diameter of 125 μm and is coated with one or two layers with a coating outer diameter of around 250 μm, and is called an optical fiber. And those with a colored coating surface. One to several optical fiber cores 5 are directly covered with an outer cover 7 and stored.

  As the tension member 6 arranged in parallel with the optical fiber core wire 5, a steel wire having an outer diameter of about 0.4 mm, glass fiber reinforced plastic (FRP), aramid fiber reinforced plastic (K-FRP), or the like can be used. As will be described later, the jacket 7 constituting the coating of the main body 2 and the support wire 3 of the optical fiber cable is formed of a flame-retardant resin.

  On both side surfaces 7 a of the main body 2, notches 8 are provided so that the V-shaped bottom portion approaches the optical fiber core wire 5. A notch 8 is cut with a tool such as a nipper, and then the outer cover 7 of the main body 2 is cut into two along the notch 8 by hand. In the present invention, the bottom side of the notch 8 is formed of the hard resin layer 10 that is harder than the outer cover. The hard resin layer 10 has an exposed shape so as to form a wall surface on the bottom side of the notch 8, for example, a shape in which a part of a circular cross section is recessed in a V shape so as to form a part of the notch 8. It is said.

  In the optical fiber cable 1 configured as described above, for example, when the number of the optical fiber core wire 5 is one, the longitudinal width L on the long side of the main body 2 is 3.1 mm, and the lateral width W on the short side is 2.0 mm. The diameter D of the support wire portion 3 can be formed with a standard external dimension of 2.0 mm, and the length K of the neck portion 4 can be 0.2 mm. The notch 8 is formed with a depth of about 0.2 mm and a width of about 0.3 mm. The bottom portion of the notch 8 is a hard resin layer 10 and the thickness S of the tip of the notch is 0. 0 in consideration of the amount of puncture of the spawning tube when using a hard resin material to be described later. It is about 4 mm. Further, the width T of the hard resin layer 10 has a width sufficient to block at least the outer diameter of the optical fiber core wire 5, and when a plurality of optical fiber core wires are arranged, a plurality of optical fiber core wires are arranged. Width to block.

  As shown in FIG. 1, the optical fiber cable of the present invention has an optical fiber core wire 5, a tension member 6, and a support wire 9 arranged on a substantially straight line in its cross section. The neck portion 4 that connects the support line portion 3 and the main body portion 2 is also arranged on the straight line. Since the notch 8 is inserted as close to the optical fiber core 5 as possible, the notch is not formed on the surface with the neck 4, and is not formed on the side surface of the optical fiber cable (the side surfaces 7 a on the left and right sides of the optical fiber core in FIG. 1). Can be put.

  When an optical connector or the like is attached to the optical fiber cable described above to form a terminal, a nipper or the like is inserted into the notch 8 at the end of the cable in order to take out the optical fiber core wire 5 in the jacket 7 and 10 mm into the hard resin layer 10. Make a notch. Next, starting from this notch, the portion of the hard resin layer 10 of the notch is torn about 100 mm by hand and bisected together with the outer cover 7. At this time, the hard resin layer 10 may be peeled off from the outer cover 7 and separated.

  For the jacket 7, a polyolefin resin is used as a base resin on the premise of non-halogen due to environmental problems. For example, LDPE (low density polyethylene), LLDPE (linear low density polyethylene), HDPE (high density polyethylene), PP (polypropylene), EEA (ethylene / ethyl acrylate copolymer) are used alone or in combination. Things are used. The base resin is mixed with 50 to 200 parts by weight of a metal oxide such as magnesium hydroxide or aluminum hydroxide with respect to 100 parts by weight of the base resin, and further, an inorganic system such as a nitrogen-based flame retardant or a phosphorus-based flame retardant. A resin having flame retardancy by adding several to several tens of parts by weight of a flame retardant is used as a jacket. The outer cover 7 is made of a resin that has a smaller breaking strength than the hard resin layer 10 in the notch portion and is easy to tear. Furthermore, the outer jacket 7 is smaller in hardness than the hard resin layer 10 in the notch portion.

  Regarding the flame retardancy of the cable, a vertical tray combustion test was performed in accordance with JIS C3521, and the cable that passed this test was used. In this test, a specified number of cables are laid on a ladder-like vertically installed tray by the specified method (approx. 150 mm or more at a 1/2 interval of the sample outer diameter) at the center of the tray. The cable is burned with a specified burner from below, and the spread of fire to the upper side of the tray is evaluated. The length per sample cable is 3.5 m, and the test pass / fail criterion is that carbon is not carbonized more than 2.5 m above the burner.

  FIG. 2 is a diagram for explaining the material used for the hard resin layer in the notch portion, and verifies the amount of piercing by the spawning tube of the pupa using an actual optical cable. FIG. 2A shows the test results of various jacket materials, and FIG. 2B shows the shape and dimensions of the optical fiber cable used in the test. The samples used for the test were determined by examining the number of piercing marks of the heels for 11 types of No. 1 to No. 11 by varying the base resin of the jacket, the hardness of the jacket, and the breaking strength. .

  As shown in FIG. 2 (B), the cross-sectional shape and dimensions of the optical fiber cable used in the test are standard as a drop optical cable, and the main body has a rectangular cross section, a horizontal width of 2.0 mm, and a vertical length. The width was 3.1 mm and the diameter of the support wire portion was 2.8 mm. The cable used in the test was 22m long, and 5-10 bundles of each sample cable were distributed and distributed in the habitat area for one month in August. I investigated.

  The hardness of the jacket was measured by a durometer (type D) defined by JIS K 7215 (plastic durometer hardness test method) of Japanese Industrial Standard (hereinafter referred to as Shore D hardness). In addition, it is necessary to consider whether the piercing depth is shallow or deep when judging the puncture mark by the spawning tube of the moth, but this value assumes that the set distance between the optical fiber from the notch tip is 0.4 mm. If the piercing depth is less than that, it shall not be counted as having the sputum resistance (the property that the optical fiber core wire is not damaged by the spawning tube of the spider), and all other cases are not considered to have sputum resistance. I counted.

  The test results are shown in FIG. Passes with less than 4 stab marks in one bundle (shown as ◯ in the figure), excellent with less than one stab mark in one bundle (indicated as ◎ in the figure), The case where the number of stab marks was less than 0.5 was judged to be particularly excellent (indicated by a triple circle in the figure). Samples Nos. 9 and 11 (Shore D hardness 49 and 43) having small hardness do not satisfy the weather resistance. Even if the hardness is simply increased as in sample No. 4 (Shore D hardness is 59), those having a small breaking strength are insufficient to satisfy the weather resistance, and the breaking strength is also required.

As a result, sample Nos. 1-3, 5-8, and 10 using a jacket having a Shore D hardness of 50 or more and a breaking strength of 14 MPa or more passed. A sample using a jacket having a Shore D hardness of 60 or more and a breaking strength of 16.5 MPa or more was excellent. A sample using a jacket having a Shore D hardness of 63 or more and a breaking strength of 22 MPa or more was particularly excellent.
Judging comprehensively from the above test results, it is preferable that the sheath material for weathering has a Shore D hardness of 50 or more and a breaking strength of 14 MPa or more.

  However, it is difficult to add a flame retardant to an optical fiber cable made of such a hard jacket, and even if it can be added, a predetermined hardness and breaking strength cannot be obtained. Therefore, in the present invention, as described with reference to FIG. 1, most of the jacket is made of the above-described flame-retardant resin to increase the flame retardancy, and the optical fiber core wire is damaged by piercing the spawn of the spider. The above-described hard resin material is used only for the bottom portion of the notch for tearing the envelope, which is likely to occur, to suppress damage to the optical fiber core wire caused by wrinkles. Thereby, it is set as the optical fiber cable provided with the flame retardance and weather resistance.

  FIG. 3 is a view showing an example of a crosshead for integrally molding the outer cover of the optical fiber cable and the hard resin body at the same time. In the figure, 11 is a head portion, 12 is a die, 13 is a nipple, 14 is a resin supply path, 15 is a die hole, 16 is an optical fiber core hole, 17 is a tension member hole, 18 is a support wire hole, Reference numeral 19 denotes a hole for a hard resin layer, and 19a and 19b denote sub supply paths.

  As shown in FIG. 3 (A), the head portion 11 of the crosshead has, for example, a die 12 provided with a die hole 15 for shaping the outer shape at the front portion, and a resin supply path between the die 12 and the die 12. The nipple 13 is coupled so as to have 14. The resin supply path 14 is extruded and supplied with a thermoplastic resin for the outer cover, and is extruded through a die hole 15 (a shape indicating the outer shape of the outer cover of the optical cable). At the tip of the nipple 13, there are provided an optical fiber core wire hole 16 through which the optical fiber core wire is inserted, a tension member hole 17 through which the tension member is inserted, and a support wire hole 18 through which the support wire is inserted.

  Further, the nipple 13 is provided with a hard resin layer hole 19 for extruding a hard resin layer so as to sandwich the optical fiber core wire hole 16 from both sides. The hard resin layer hole 19 communicates with the sub supply paths 19a and 19b. In the hard resin layer hole 19, the hard resin material supplied through the sub supply paths 19 a and 19 b is formed into a predetermined shape and is slightly cured. Next, the optical fiber core wire extruded through the optical fiber core wire hole 16 and the tension member passed through the tension member hole 17 are covered and integrated with the resin for the outer cover of the resin supply path 14. It becomes.

  FIG. 3 (B) is a view of the tip of the nipple 13 as viewed from the direction of arrows (aa) in FIG. 3 (A), and the wire material inserted into each is a predetermined shape as shown in FIG. The above holes 16 to 18 are provided so as to have the following arrangement relationship. The holes 19 for the hard resin layer are provided on both sides of the hole 16 for the optical fiber core wire, are formed by holes having a cross-sectional shape of the hard resin layer 10 shown in FIG.

  FIG. 3C shows a cross section taken along the line (bb) in FIG. 3B and shows an arrangement state of the hard resin layer holes 19 and the sub supply paths 19a and 19b. As is apparent from this figure, the hard resin layer holes 19 are provided so as to sandwich both sides of the optical fiber core hole 16 through which the optical fiber core wire is inserted, and a resin material is provided in each of the hard resin layer holes 19. The sub-supply paths 19a and 19b for feeding the resin are shunted into two so as to oppose each other, and the resin supply path 14a for supplying the resin material for the jacket is provided separately so as not to cross. . Note that the two sub supply paths 19b are joined together and connected to an external sub extruder.

  The hard resin layer at the bottom of the notch is made of a resin material different from the resin for the jacket, is supplied from the separately provided sub supply paths 19a and 19b, and is molded into a predetermined shape by the nipple 13 in advance. The shape of the hard resin layer is shown as an example of a circular shape having a bottom portion of a V-shaped notch. However, the shape of the hard resin layer is not limited to a circle, and forms a part of a notch such as an ellipse or a rectangle. What is necessary is just a shape to interrupt. The hard resin layer molded and heated in the nipple 13 is integrated with the resin material for the outer jacket in the resin supply path 14, but it is maintained in a certain shape and mixed with the resin for the outer jacket. Absent.

  If the melting point resin and the hard resin have the same melting point, the resin materials are fused and integrated, and the adhesive force at the interface becomes extremely high. For example, as described above, a polyolefin resin having a Shore D hardness and a breaking strength equal to or higher than a predetermined value is used as the hard resin, and a flame retardant is added to the outer jacket to reduce the hardness and the breaking strength. When a resin with improved properties is used, the adhesive strength at the interface between the two is large.

  In the optical fiber cable according to the present invention, only the bottom part of the notch for tearing the awning tube of the cocoon, which is easy to pierce, is formed with a resin material having hardness and breaking strength suitable for heel resistance. In addition, since the outer covering occupying the other whole portion is formed of a material having flame retardancy, it can have both weather resistance and flame retardancy. As for the tearability, the thickness S of the hard resin layer at the tip of the notch is made as small as possible (for example, 0.4 mm to 0.00 mm) in consideration of the amount of puncture of the spawning tube of the cocoon to the hard resin material. By setting the thickness to 5 mm, it is possible to prevent the tearability from being impaired.

DESCRIPTION OF SYMBOLS 1 ... Optical fiber cable, 2 ... Main part, 3 ... Support line part, 4 ... Neck part, 5 ... Optical fiber core wire, 6 ... Tension member, 7 ... Outer cover, 7a ... Side surface of main part, 8 ... Notch, 9 DESCRIPTION OF SYMBOLS: Steel wire, 10 ... Hard resin layer, 11 ... Head part, 12 ... Die, 13 ... Nipple, 14 ... Resin supply path, 15 ... Die hole, 16 ... Optical fiber core wire hole, 17 ... Tension member hole, 18 ... support wire hole, 19 ... hard resin layer hole, 19a, 19b ... sub supply path.

Claims (3)

The main body part and the support line part are connected via a neck part that can be easily cut. A notch is provided, and the support line portion is an optical fiber cable arranged on an extension line connecting the tension member and the center of the optical fiber core wire,
The outer jacket is formed of a flame-retardant resin, and the bottom of the notch is formed of a resin that is harder than the outer jacket and has a width that covers the optical fiber core.   2. The light according to claim 1, wherein the resin harder than the jacket is formed of a hard resin having a polyolefin resin as a base resin, a Shore D hardness of 50 or more, and a breaking strength of 14 MPa or more. Fiber cable.   The optical fiber cable according to claim 2, wherein the resin harder than the jacket is formed of a hard resin having a Shore D hardness of 63 or more and a breaking strength of 22 MPa or more.

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