JP5529813B2 - Fiber optic cable - Google Patents

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 with protective bodies and optical cables with a structure in which the position and direction of the notch are changed so that the spawning tube of the spider does not pierce the optical fiber core wire have been proposed.

  However, there are cases in which the spawning tube of the moth is also inserted from a portion other than the notch, and only a structural correspondence is not sufficient. For example, in Patent Document 1, a tensile strength of 15 to Using a 40 MPa, resin with a Shore D hardness of 50-80, the bear spawning tube is designed not to pierce the outer cover by 0.6 mm or more. Similarly, in Patent Document 2, in order to obtain a jacket having a Shore D hardness of 55 or more, an optical fiber is coated with a resin composition mainly composed of an ethylene / α-olefin copolymer or a polyethylene resin. Is disclosed.

  Further, in Patent Document 3, the outer side of the optical fiber arranged in the 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. It has been shown to block the invasion of the laying tube.

JP 2008-129062 A International Publication No. 08/090880 Pamphlet JP 2009-25425 A

  As disclosed in Patent Document 1 and Patent Document 2, the effect of wrinkle countermeasures can be expected by making the entire jacket covering the optical fiber core wire hard. However, when the tensile strength of the jacket is too large, there is a problem that it is difficult to tear and remove the jacket due to formation of 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.

  Moreover, in patent document 3, two removal operations called the tear removal of the jacket which covers the whole, and the removal of a reinforcement layer are needed. Although it is possible to remove the outer cover and the reinforcing layer at the same time, integration is difficult because the resin material of the outer cover and the reinforcing layer is different. In addition, even if the outer cover and the reinforcing layer are bonded and integrated, it is necessary to make the coating of the optical fiber strands non-adhering. There is a problem that it becomes expensive.

Furthermore, since the drop optical cable is drawn into a subscriber's house or the like, high flame retardancy is required. Therefore, a flame retardant is added to impart flame retardancy to the outer cover, but if this additive is contained in a large amount, it becomes brittle in strength and has a problem that the hardness is also lowered.
In addition, the optical cable may be used in a cold region, and if the cable is bent at a low temperature, the outer cover may be cracked. For this reason, the jacket is also required to have cold resistance as a basic characteristic.

  In addition, important issues required in manufacturing an optical cable include that it can be manufactured at low cost and that the manufacturing process is not complicated. Therefore, there is a need for a new outer cover composition that can express desired characteristics while using an inexpensive and highly processable resin.

  The present invention has been made in view of the above-mentioned problems in conventional optical fiber cables, and suppresses optical fiber damage caused by piercing of a spawning spawn tube without using a protective body or a reinforcing layer. In addition, an object of the present invention is to provide an optical fiber cable that has flame resistance and cold resistance and can easily tear the jacket.

In the optical fiber cable of 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 formed in a rectangular shape with a jacket with tension members arranged on both sides of the optical fiber core wire. It is covered in a lump and is provided with notches for jacket tearing on both side surfaces, and the support line portion is disposed on an extension line connecting the center of the tension member and the optical fiber core wire.
Further, the jacket has (b) an aspect ratio of 2 or less with respect to 100 parts by weight of polyethylene (a) 40 to 70 parts by weight of high density polyethylene and 60 to 30 parts by weight of linear low density polyethylene. It is formed of a resin composition having a Shore D hardness of 57 or more, comprising 30 to 120 parts by weight of a flame retardant filler and 1 to 10 parts by weight of (c) a phosphorus-based flame retardant ( Claim 1).

  In a preferred embodiment of the optical fiber cable of the present invention, the flame retardant filler is magnesium hydroxide and / or aluminum hydroxide (claim 2).

  Furthermore, another preferred embodiment of the optical fiber cable of the present invention is characterized in that a separation distance between the optical fiber core wire and a notch tip is 0.4 mm or more.

  According to the present invention, it is possible to prevent damage to the optical fiber due to the puncture of the spawning tube of the spider by itself without using a protective body, a reinforcing layer, etc., and to provide flame resistance and cold resistance. It is possible to provide an optical fiber cable that can be easily torn. Such an optical fiber cable can be made of an inexpensive and highly workable resin material.

It is the schematic which shows embodiment of the optical fiber cable by this invention.

Hereinafter, the optical fiber cable of the present invention will be described in detail.
FIG. 1A shows an embodiment using a single-core optical fiber core of the optical fiber cable of the present invention, and FIG. 1B shows a 4-fiber optical fiber ribbon. Another embodiment using two sheets is shown. The number of cores of the optical fiber core wire is not limited to these, and can be any number of cores such as two cores and four cores.

  In the figure, 1, 1 'is an optical fiber cable, 2 is a main body, 3 is a support line, 4 is a neck, 5 is an optical fiber core, 5' is an optical fiber ribbon, 6 is a tension member, 7 is A jacket, 7a is a side surface of the main body, 8 is a notch, and 9 is a steel wire.

  An optical fiber cable 1 shown in FIG. 1A has a self-supporting structure in which a body part 2 having a rectangular cross section and a support line part 3 having a circular cross section are connected by a narrow neck part 4 that can be easily cut. It is formed. The main body 2 has a single optical fiber core 5 disposed in the center, tension members (also referred to as tension members) 6 disposed on both sides thereof, and an outer sheath 7 (also referred to as a sheath) that is integrally covered. It becomes. Further, notches 8 are provided on both side surfaces 7 a of the main body 2 so that the V-shaped bottom portion approaches the optical fiber core wire 5.

  The support wire portion 3 is a steel wire 9 (outer diameter of about 1.2 mm) made of a single core wire or a stranded wire, and is on or near an extension line of the line Y connecting the center of the optical fiber core wire 5 and the tension member 6 Is provided. 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 wire 2 in the present invention is, for example, 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. Including those having a colored surface or coated 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 (KFRP), 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 hard resin for weathering.

  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 separation distance S between the bottom end of the notch 8 and the optical fiber core wire 5 is set to about 0.4 mm in consideration of an outer sheath material and tearability described later. If it is 0.3 mm, the optical fiber may be damaged by the spawning tube.

  An optical fiber cable 1 ′ shown in FIG. 1 (B) is an arrangement in which two optical fiber tape cores 5 ′ are stacked in place of the optical fiber core wire 5 in FIG. 1 (A). Is the same as that of FIG. However, since the number of cores of the optical fiber is 8, the longitudinal width L on the long side is 3.7 mm. The width W of the other short side is 2.0 mm, the diameter D of the support wire portion 3 is 2.0 mm, the length K of the neck portion 4 is 0.2 mm, and the separation distance between the notch 8 and the optical fiber core wire 5. Setting S to 0.4 mm can be the same as that in FIG.

  The “optical fiber core wire” in the present invention includes the optical fiber tape core wire 5 ′. In an optical fiber cable including an optical fiber ribbon or an optical fiber cable including a plurality of optical fiber cores, there are a plurality of lines connecting each optical fiber core and the center of the tension member. Therefore, the support line portion is in the vicinity of the extension line of the line connecting any one of the optical fiber core wires and the tension member.

  When an optical connector or the like is attached to the optical fiber cable 1 or 1 ′ described above to form a terminal, the notch 8 at the end of the cable is removed with a nipper or the like in order to take out the optical fiber core wires 5 and 5 ′ in the jacket 7 Make a cut of about 10 mm. Next, starting from this notch, the portion of the notch 8 is torn about 100 mm by hand to divide the outer cover 7 into two. In order to tear the outer cover 7 by hand, the distance S between the tip of the notch 8 and the optical fiber cores 5 and 5 ′ is greatly related. However, if the distance reaches the optical fiber core and the separation distance S is increased to avoid this, tearing becomes difficult.

  Further, when the above-mentioned separation distance S is set to a predetermined value, when the tensile strength of the jacket is small, it is easy to tear the jacket, but the amount of piercing by the spawning tube of the cocoon increases and the separation distance S Need to be larger. On the other hand, when the hardness of the jacket is large and the tensile strength is large, the amount of puncture by the spawning tube of the cocoon can be suppressed, but when the tensile strength is too large, tearing becomes difficult. In the above embodiment, the separation distance S between the notch 8 and the optical fiber cores 5 and 5 ′ is about 0.4 mm. ) And tearing property are obtained at a low cost, the separation distance S is more preferably 0.4 mm or more. In order to facilitate tearing, S is preferably 0.6 mm or less.

  In addition to the above structural features, the optical fiber cable of the present invention has both the weather resistance and tear resistance (low tear strength), and further uses an outer sheath material excellent in flame resistance and cold resistance. Features. Cold resistance is an important characteristic for preventing damage when a cable is bent in a cold region.

The composition of the jacket material forming the jacket of the optical fiber cable of the present invention will be described.
The jacket of the optical fiber cable of the present invention has (b) an aspect ratio with respect to 100 parts by weight of polyethylene (a) 40 to 70 parts by weight of high density polyethylene and 60 to 30 parts by weight of linear low density polyethylene. 2 or less and 30 to 120 parts by weight of a flame retardant filler and (c) 1 to 10 parts by weight of a phosphorus-based flame retardant, and the Shore D hardness of the entire resin composition is 57. That's it. The aspect ratio is preferably 1 or more.
With such a resin composition, it has excellent weather resistance, flame resistance and cold resistance, and it is easy to tear the notch for jacket tearing by hand. The workability can be improved. In particular, since the optical fiber cable of the present invention has a Shore D hardness of 57 or more of the entire resin composition constituting the jacket, damage to the optical fiber due to piercing by a spawning tube of salmon is remarkably suppressed.

In the present invention, the (a) polyethylene resin comprises 40 to 70 parts by weight of high density polyethylene and 60 to 30 parts by weight of linear low density polyethylene.
In order to improve the low temperature brittleness, an elastomer such as styrene-ethylene-butene-styrene block copolymer, ethylene-propylene copolymer, ethylene-butene copolymer may be added. When these resins are added, the resin is added to 1 to 30% by weight in the resin combined with the (a) polyethylene resin.

The resin composition of the present invention contains (b) a flame retardant filler having an aspect ratio of 2 or less as a flame retardant.
The aspect ratio is expressed by the major axis of the filler / the thickness of the filler. The larger the aspect ratio, the more flat the plate becomes. In the present invention, a low aspect ratio filler having an aspect ratio of 2 or less, preferably 1 or more and 2 or less, more preferably 1 or more and 1.5 or less is used as a flame retardant. The aspect ratio of the flame retardant filler that is usually used is 3 or more.
By setting the aspect ratio to 2 or less, flame resistance and good tearability can be obtained. Thereby, it becomes easy to tear the notch for jacket tearing by hand, and the workability of taking out the core wire at the time of laying can be improved. A commercially available flame retardant filler having an aspect ratio of 2 or less can be selected and used.
The flame retardant filler that can be used in the present invention is not particularly limited as long as the aspect ratio is 2 or less, but magnesium hydroxide and / or aluminum hydroxide is preferable from the viewpoint of flame retardancy.
Magnesium hydroxide and aluminum hydroxide may be either natural products or synthetic products, but synthetic products are preferred because they are excellent in mechanical properties and cold resistance.
The addition amount of the flame retardant filler having an aspect ratio of 2 or less is 30 to 120 parts by mass, preferably 50 to 90 parts by mass with respect to 100 parts by mass of the resin. If the added amount is less than 30 parts by mass, the tearability is inferior (a high tearing force is required at the time of work). is there.

Further, in the present invention, (c) a phosphorus-based flame retardant is used in combination with the above-described flat flame retardant filler.
Although it does not specifically limit as a phosphorus flame retardant, For example, red phosphorus, aromatic phosphate ester, ammonium polyphosphate, melamine polyphosphate, piperazine polyphosphate etc. are mentioned, 1-10 mass parts with respect to 100 weight part of resin , Preferably 1 to 5 parts by mass. When the amount of the phosphorus-based flame retardant is less than 1 part by mass, it is difficult to impart flame retardancy to a desired degree.
Moreover, you may add 1-30 mass parts of inorganic substances, such as a zinc oxide, zinc borate, an antimony trioxide, a calcium carbonate, or organic substances, such as a melamine cyanurate, as a flame retardant adjuvant with respect to 100 mass parts of resin.

  The jacket of the present invention has a Shore D hardness of 57 or more by adding a flame retardant filler and a phosphorus flame retardant to polyethylene as described above. In order to prevent damage to the optical fiber due to the puncture of the spider's egg-laying tube, it is necessary to set the Shore D hardness of the jacket to 57 or more. In order to easily take out the optical fiber core wire by tearing the outer sheath of this structure by hand, the aspect ratio of the flame-retardant filler needs to be 2 or less. And in order to ensure the flame retardance of an optical fiber cable, the flame retardant added to a jacket needs to be a phosphorus flame retardant.

  In addition to the flame retardant, silicone, fatty acid amide, stearic acid, stearic acid metal salt, paraffin or the like may be added as a processing aid to the jacket of the optical fiber cable of the present invention. In particular, the fatty acid amide (lubricant) is blended in order to improve the jacket removability, and is useful in an optical fiber cable that needs to remove the jacket when laying. Similarly, components generally used as a resin compounding agent such as an antioxidant and an antifungal agent may be added.

  The resin composition used in the optical fiber cable of the present invention can be obtained by melting and kneading each of the above components using a kneader apparatus that is usually used, such as a twin-screw kneading extruder, a Banbury mixer, a kneader, or a roll. it can. The optical fiber cable according to the present invention includes an optical fiber core 5 or an optical fiber tape core 5 ′, a tension member 6 formed of, for example, aramid fiber reinforced plastic (KFRP), and a steel wire 9 as a support wire by an extrusion method. Can be produced by coating the above resin composition melt-kneaded in advance around

  Hereinafter, the results of evaluation tests using examples and comparative examples according to the present invention will be shown, and the present invention will be described in more detail. The present invention is not limited to these examples.

  Using the jacket materials (Examples 1 to 3, Comparative Examples 1 to 7) having the compositions shown in Table 1, various characteristics were evaluated in the following manner. In order to improve the long-term stability of the jacket, 1 part by weight of an antioxidant (hindered phenol type) was added in common to all of the examples and comparative examples.

A sample to be used for the evaluation test was obtained by first heating and mixing each of the blending components shown in Table 1 with an oil heating type open roll heated to 200 ° C., and molding this. For the hardness, tensile strength, tensile elongation, and low temperature embrittlement test, the product obtained by mixing the rolls was molded into a sheet with a press. On the other hand, for the samples used in the JIS 60-degree inclined combustion test and cable tearability evaluation test, those obtained by the roll mixing were cut into pellets with a pelletizer, and the pellets were optical fiber cores using a 65 mmφ extruder. The wire was covered around the wire to obtain the drop cable shape (1 core and 8 cores) shown in FIG. 1 (A) or (B). The obtained cable sample had a lateral width W of 2.0 mm, a longitudinal width L of 3.1 mm, a diameter of the support wire portion of 2.8 mm, and a separation distance S between the optical fiber core wire and the notch of 0.4 mm.
The evaluation results of each example are also shown in Table 1.
The unit of each numerical value in the material composition in the table is “part by weight”.

<Evaluation test method>
[hardness]
The hardness of the jacket was measured using a durometer (type D) defined by JIS K7215 (plastic durometer hardness test method) of Japanese Industrial Standard (hereinafter referred to as Shore D hardness). The criterion for the hardness of the jacket is that the Shore D hardness is 57 or more is a necessary condition for weather resistance.

[Tensile strength]
The tensile strength of the jacket was measured using a No. 2 test piece in accordance with JIS K7113 of Japanese Industrial Standard. The criterion for determining the tensile strength is that when the spawning tube of a spider is pierced into the outer cover, the outer cover is not deformed and must be 15 MPa or more, which can prevent a space for laying eggs. Condition.

[Tensile elongation]
The tensile elongation of the jacket was performed using a No. 2 test piece in accordance with JIS K7113 of the Japanese Industrial Standard. The criterion for determining the tensile elongation of the jacket was an essential condition of 300% or more, which does not break even when the cable is bent.

[Flame retardance (60 degree inclined combustion test)]
For the test, 1-core and 8-core cables were used. This was performed in accordance with Japanese Industrial Standard JIS C3005. A sample of about 300 mm in length collected from the finished product is supported at an inclination of about 60 degrees with respect to the horizontal, and the tip of the reducing flame is applied to a position about 20 mm from the lower end of the sample until it burns within 30 seconds. , Take out the flame quietly. And the case where it extinguished naturally was set as the pass.

[Cold resistance (low temperature embrittlement test)]
The low-temperature embrittlement test (cracking temperature) is for verifying impact resistance at low temperatures, and was performed in accordance with Japanese Industrial Standard JIS C3005. The criterion was that a sheet-like test piece having a thickness of 2 mm was hit with a hitting tester at a low temperature of −30 ° C. or lower, and no crack was generated on the sheet surface.

[Tearability (Tear force)]
A 1-core cable was used for the test. The notch of the outer cover of the drop cable was previously torn between several centimeters, both of the tears were fixed with a chuck of a tensile tester, pulled in the 180 ° direction at a pulling speed of 200 mm / min, and then torn 50 mm. The maximum value at that time was taken as the tearing force. The criterion for determining the tearing force is a case where it is less than 12N from the viewpoint of workability.

  As shown in the above results, it was confirmed that the jacket materials of Examples 1 to 3 composed of the composition components of a predetermined blending amount satisfy the performance required for essential characteristics.

  On the other hand, in Comparative Example 1 in which the blending amount of the flame retardant filler is less than the specified amount, the flame retardancy and tearability (core wire takeout property) did not satisfy the standard values. In Comparative Example 5, there were few flame retardants and the combustion test failed. Comparative Example 7 in which the flame retardant was other than the phosphorus flame retardant failed the combustion test.

  In Comparative Example 2 in which the blending amount of the flame retardant filler is larger than the specified amount, the desired performance with respect to cold resistance was not obtained.

  In Comparative Examples 3 and 4, since the aspect ratio of the flame retardant filler was larger than 2, the desired performance with respect to tearability was not obtained.

  In Comparative Example 6, since the blending amount of the phosphorus-based flame retardant was larger than the specified amount, desired performance satisfying weather resistance with respect to tensile strength could not be obtained.

  The optical fiber cable according to the present invention can ensure hardness and tensile strength suitable for weathering resistance by using the above-described jacket material, and can also ensure cold resistance and flame resistance. Moreover, the jacket formed of the above-described jacket material can be torn by hand while being highly rigid, and the optical fiber core wire in the jacket can be taken out without requiring skills. Further, the jacket material of the optical fiber cable is excellent in tensile elongation required for the optical fiber cable as a basic characteristic.

DESCRIPTION OF SYMBOLS 1,1 'Optical fiber cable 2 Main-body part 3 Support line part 4 Neck part 5 Optical fiber core wire 5' Optical fiber tape core wire 6 Tension member 7 Outer cover 7a Side surface of outer cover 8 Notch 9 Steel wire

Claims (3)

The main body part and the support line part are connected via an easily cut neck part. The main body part is provided with tension members on both sides of the optical fiber core wire and is covered in a rectangular shape with a jacket, and is externally attached to both side surfaces. A notch for tearing is provided, and the support line portion is an optical fiber cable arranged on an extension line connecting the center of the tension member and the optical fiber core wire,
The jacket is composed of (a) 100 parts by weight of polyethylene comprising 40 to 70 parts by weight of high density polyethylene and 60 to 30 parts by weight of linear low density polyethylene, and (b) a flame retardant having an aspect ratio of 2 or less. An optical fiber cable comprising a resin composition having a Shore D hardness of 57 or more, comprising 30 to 120 parts by weight of a filler and (c) 1 to 10 parts by weight of a phosphorus flame retardant .   2. The optical fiber cable according to claim 1, wherein the flame retardant filler is magnesium hydroxide and / or aluminum hydroxide.   The optical fiber cable according to claim 1 or 2, wherein a separation distance between the optical fiber core wire and a notch tip is 0.4 mm or more.