JP2021162810A - Coated optical fiber and optical fiber cable - Google Patents

Abstract

To provide a coated optical fiber and an optical fiber cable that make it possible to determine presence/absence of breakage of a glass fiber by visual recognition without passing light through a coated optical fiber.SOLUTION: A coated optical fiber 2 includes a glass fiber 21 and a covering member (exemplified by a colored layer 25) covering a periphery of the glass fiber. A breaking elongation of a material of the covering member is lower than that of the glass fiber. Preferably, the covering member has a hardness of H or more in pencil hardness. More preferably, the covering member has an elastic modulus of 2.5 GPa or more.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to an optical fiber core wire and an optical fiber cable, and more particularly to an optical fiber core wire and an optical fiber cable including a glass fiber and a coating member that covers the periphery of the glass fiber.

In recent years, with the progress of cloud computing and the like, the construction of large-scale data centers is progressing. Fiber optic cables are used to connect these data centers to each other. For optical fiber cables, there is an increasing demand for multi-core and high-density optical fiber core wires in order to prepare for the expected increase in transmission capacity. For example, Patent Document 1 discloses a structure of an optical fiber cable capable of achieving high density.

JP-A-2017-134267

By the way, the optical fiber cable connecting the data centers is laid in the existing pipeline. Since this pipeline space is limited in advance, it is necessary to pack the optical fiber core wire into the optical fiber cable at a high density in order to meet the demand for high density. However, if the mounting density of the optical fiber core wire is increased, the degree of freedom of movement of the optical fiber core wire is limited in the optical fiber cable. Therefore, if the optical fiber cable is bent or expanded or contracted depending on the temperature, the optical fiber core wire is locally bent in a narrow space inside the optical fiber cable. When an external force is applied to the optical fiber core wire, the glass fiber may break, but in order to confirm whether or not the glass fiber is broken, it is necessary to pass light through the optical fiber core wire, which is troublesome.

The present disclosure has been made in view of the above circumstances, and the presence or absence of breakage of the glass fiber can be visually determined without passing light through the optical fiber core wire and the optical fiber core wire and the optical fiber cable. The purpose is to provide.

The optical fiber core wire according to one aspect of the present disclosure is an optical fiber core wire composed of a glass fiber and a coating member that covers the periphery of the glass fiber, and the material of the coating member is more broken than the glass fiber. Growth is low.

According to the above, the presence or absence of breakage of the glass fiber can be visually determined without passing light through the optical fiber core wire.

It is sectional drawing which shows an example of the optical fiber cable which concerns on one aspect of this disclosure. It is a figure which shows an example of the structure of an optical fiber core wire. It is a figure which shows an example of the structure of the intermittent tape core wire.

[Explanation of Embodiments of the present disclosure]
First, the contents of the embodiments of the present disclosure will be listed and described.
The optical fiber core wire according to the present disclosure is (1) an optical fiber core wire composed of a glass fiber and a coating member that covers the periphery of the glass fiber, and the material of the coating member is more broken than the glass fiber. Growth is low.
The breaking elongation of the covering member is made lower than the breaking elongation of quartz glass. Therefore, when an external force is applied to the optical fiber core wire, the coating member may crack or become cloudy before the glass. Therefore, it is possible to visually predict the breakage of the glass without passing light through the optical fiber core wire.
(2) In one aspect of the optical fiber core wire of the present disclosure, the hardness of the covering member is equal to or higher than the pencil hardness H.
When the pencil hardness is less than H, the coefficient of friction becomes large and the optical fiber core wires tend to tack each other. When the optical fiber cores are tacked with each other, lateral pressure is applied to the other optical fiber cores, which may cause microbend locally. However, if the pencil hardness is H or higher, the optical fiber cores are difficult to tack with each other. Therefore, the necessary transmission characteristics can be secured. The pencil hardness is measured according to the new JIS K5600.

(3) In one aspect of the optical fiber core wire of the present disclosure, the elastic modulus of the covering member is 2.5 GPa or more.
When the elastic modulus of the covering member is less than 2.5 GPa, the increase in transmission loss cannot be suppressed when a lateral pressure is applied. Therefore, if the elastic modulus is set to 2.5 GPa or more, an increase in transmission loss can be suppressed even when a lateral pressure is applied, and necessary transmission characteristics can be secured.
(4) In one aspect of the optical fiber cable of the present disclosure, the covering member contains an acrylic polyol resin or a liquid crystal polymer.
Therefore, it has flexibility while having high hardness.
(5) One aspect of the optical fiber cable of the present disclosure includes an aggregate core in which a plurality of the above-mentioned optical fiber core wires are collected and wound by presser winding, and a cable jacket that covers the periphery of the aggregate core.
It is possible to provide an ultra-multicore optical fiber cable capable of laying as many optical fiber core wires as possible in an existing pipeline.

[Details of Embodiments of the present disclosure]
Hereinafter, preferred embodiments of the optical fiber core wire and the optical fiber cable according to the present disclosure will be described with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view showing an example of an optical fiber cable according to one aspect of the present disclosure, and FIG. 2 is a diagram showing an example of a structure of an optical fiber core wire. Further, FIG. 3 is a diagram showing an example of the structure of the intermittent tape core wire.

The optical fiber cable 10 shown in FIG. 1 is a slotless type, and has, for example, a round aggregate core 11 and a cable jacket 13 formed around the aggregate core 11. In the collective core 11, for example, 75 pieces of 4-core intermittent tape core wires 1 are used to form 300 cores.
The intermittent tape core wire is formed by arranging a plurality of optical fiber core wires in a parallel row and intermittently connecting adjacent optical fiber core wires by a connecting portion and a non-connecting portion. As shown in FIG. 2, the optical fiber core wire 2 accommodated in the intermittent tape core wire is composed of a glass fiber 21, a primary resin layer 22, a secondary resin layer 23, and a colored layer 25. The outer periphery of the glass fiber 21 is coated with the primary resin layer 22, and the outer periphery thereof is coated with the secondary resin layer 23, which is also called an optical fiber wire 24.

The glass fiber 21 is an optical waveguide having a core portion and a clad portion and having a standard outer diameter of, for example, 125 μm. The glass fiber 21 is made of quartz glass. The primary resin layer 22 is, for example, a coating layer made of a soft ultraviolet curable resin having an outer diameter of about 190 μm to 200 μm and having a relatively low Young's modulus. The secondary resin layer 23 is, for example, a coating layer formed of a hard ultraviolet curable resin having an outer diameter of about 240 μm to 250 μm and having a relatively high Young's modulus. The outer diameter of the optical fiber core wire is not limited to this, and may be, for example, about 200 μm or 150 μm.

The colored layer 25 is formed, for example, having a thickness of about 5 μm to 10 μm, and when the optical fiber core wire 2 is housed in the optical fiber cable 10 as a single core wire, the colored layer 25 is made of a high-hardness resin described later. It becomes a layer, and the colored layer 25 corresponds to the covering member of the present disclosure. When the colored layer 25 is transparent, the secondary resin layer 23 may be formed of a high-hardness resin described later. In this case, the secondary resin layer 23 corresponds to the covering member of the present disclosure.

FIG. 3A shows a state in which the intermittent tape core wires are opened in the arrangement direction. 3 (B) is a cross-sectional view taken along the line BB of FIG. 3 (A), FIG. 3 (C) is a cross-sectional view taken along the line CC of FIG. 3 (A), and FIG. A cross-sectional view taken along the line DD of FIG. 3A is shown. In the intermittent tape core wire 1, for example, adjacent core wires are intermittently connected by a connecting portion 3 and a non-connecting portion 4. Specifically, a tape coating 5 made of a high-hardness resin, which will be described later, is provided around each optical fiber core wire 2, and in the connecting portion 3 shown in FIGS. 3 (B) and 3 (D), the connecting portion 3 is provided. Adjacent tape coatings 5 are connected, and in the non-connecting portions 4 shown in FIGS. 3 (B) to 3 (D), the adjacent tape coatings 5 are separated without being connected.

When the intermittent tape core wire 1 is housed in the optical fiber cable 10, the tape coating 5 corresponds to the coating member of the present disclosure.
The intermittent tape core wire in FIG. 3 is an example of four optical fiber core wires, but the number of optical fiber core wires accommodated is arbitrary, and the intermittent tape core wire is composed of 8 cores, 12 cores, and the like. Alternatively, the connecting portion and the non-connecting portion may be intermittently connected every two cores.

On the other hand, the collective core 11 of the optical fiber cable 10 is formed by, for example, bundling 5 intermittent tape core wires 1 into a 20-core unit, bundling 15 20-core units, and using a presser winding tape 12 as shown in FIG. It is vertically attached or rolled horizontally to form a round shape. The presser foot tape 12 corresponds to the presser foot of the present disclosure. In this way, if the intermittent tape core wire 1 is used, it can be freely deformed in the assembly core 11, so that the optical fiber core wire 2 can be assembled at a high density. As a result, it is possible to provide an ultra-multicore optical fiber cable 10 capable of laying as many optical fiber core wires 2 as possible in the existing pipeline.

The outside of the presser foot tape 12 is covered with a cable jacket 13 made of, for example, PE (polyethylene), PVC (polyvinyl chloride), or the like.
The cable outer cover 13 includes two tension members (also referred to as tensile strength bodies) 14 for maintaining strength in the longitudinal direction, and for example, two tear cords 15 for tearing the cable outer cover 13 in the longitudinal direction of the cable. , The cable outer cover 13 is vertically attached and buried at the time of extrusion molding.

For the tension member 14, a wire rod having a proof stress against tension and compression, for example, a steel wire or FRP (Fiber Reinforced Plastics) is used, and is provided on both sides of the collective core 11.
The tear string 15 is provided on each side of the collecting core 11 at a position on a line orthogonal to the line connecting the centers of the two tension members 14. The tear string 15 is, for example, a string-shaped member having a circular cross section made of a resin material such as nylon or polyester, and is arranged in the same straight line along the radial direction of the collective core 11. A protrusion 16 is formed on the cable outer cover 13 at the time of extrusion molding so that the embedded position of the tear string 15 can be visually recognized from the outside.

Taking the case where the intermittent tape core wire 1 is housed in the optical fiber cable 10 as an example, the material of the tape coating 5 is a high hardness resin (for example, an acrylic polyol resin, which is a hitaloid manufactured by Hitachi Chemical Co., Ltd. (registered). Trademark) etc.) are used.
Hitaroid is an ultraviolet curable (UV) resin, which is composed of a mixture of an organic material and an inorganic material (also referred to as an organic-inorganic hybrid). As a result, in addition to high transparency and adhesion, it has high hardness and flexibility.

As the cured coating film characteristics of Hitaroid (for example, Hitaroid UV219), the elongation at break is lower than that of glass, the pencil hardness is 4H, and the elastic modulus is 2.5 GPa or more. The coefficient of static friction is 0.13, the coefficient of dynamic friction is 0.06, and the adhesion is PET (polyethylene terephthalate), PC (polycarbonate), PMMA (polymethylmethacrylate), ABS (acrylonitrile, butadiene, styrene copolymer synthesis). It is good in relation to each resin.

In the above description, an example of hitaloid as a high hardness resin has been given. However, the present disclosure is not limited to this example. For example, it is also possible to use a liquid crystal polymer (Liquid Crystal Polymer, hereinafter referred to as LCP) as the high hardness resin.
LCP is a thermoplastic resin, for example, the tensile elongation at break is about 1.5% to 6.3% lower than that of glass, the pencil hardness is H or more, and the flexural modulus is about 8 GPa to 11 GPa.

Since the high hardness resin as described above is used, the breaking elongation of the tape coating 5 is lower than the breaking elongation of the glass fiber 21 (about 6% or 7%).
In this way, if the breaking elongation of the tape coating 5 is made lower than the breaking elongation of the glass fiber 21, when an external force is applied to the optical fiber core wire 2, the tape coating 5 may crack before the glass fiber 21. , Cloudy. Therefore, it is possible to visually judge without passing light through the optical fiber core wire 2, and it is possible to predict the breakage of the glass fiber 21.

Further, when examining the characteristics of the tape coating 5, first, the hardness of the tape coating 5 is preferably a pencil hardness H or higher. When the hardness of the tape coating 5 is less than the pencil hardness H, the friction coefficient becomes large and the intermittent tape core wires 1 tend to tack each other. Therefore, if the pencil hardness is H or higher, the intermittent tape core wires 1 are less likely to be tacked with each other, and the necessary transmission characteristics can be secured.
Further, the friction coefficient of the tape coating 5 is preferably 0.3 or less. This is because if the friction coefficient of the tape coating 5 is set to 0.3 or less, it becomes difficult for the intermittent tape core wires 1 to tack each other.

The elastic modulus of the tape coating 5 is preferably 2.5 GPa or more. When the elastic modulus of the tape coating 5 is less than 2.5 GPa, the increase in transmission loss cannot be suppressed when a lateral pressure is applied. However, if the elastic modulus is set to 2.5 GPa or more, an increase in transmission loss can be suppressed even when a lateral pressure is applied, and necessary transmission characteristics can be secured.
The elastic modulus of the tape coating 5 is set to the highest value in the cable components (tear string 15, presser winding tape 12, etc.) excluding the glass fiber 21 and the tension member 14.

The thickness of the tape coating 5 is preferably in the range of 5 μm to 35 μm. In the tape coating 5 using the high hardness resin, hard polysiloxane particles and the like are exposed. When the intermittent tape core wires 1 are tacked with each other, the tape coating 5 exerts a lateral pressure on the tape coating 5 of the other intermittent tape core wires 1 to locally generate a microbend. Therefore, if the thickness of the tape coating 5 is set to 5 μm or more, an increase in transmission loss can be suppressed even when a lateral pressure is applied.

Further, if the tape coating 5 is configured with a high elastic modulus, a large compressive force is generated in the glass fiber 21 when the tape coating 5 shrinks during processing or in a low temperature environment, so that the glass fiber 21 is seated. You may succumb. Therefore, if the thickness of the tape coating 5 is set to 35 μm or less, buckling of the glass fiber 21 can be avoided, and an increase in transmission loss can be suppressed even if the tape coating 5 shrinks.
If the tape coating 5 contains 5% or more of polysiloxane and its particle size distribution is 1 μm or less at a 90% value, the appearance of hard polysiloxane particles can be suppressed.

In the above example, the intermittent tape core wire 1 is housed in the optical fiber cable 1, but the single core wire such as the optical fiber core wire 2 may be housed in the optical fiber cable 10. In this case, the bending rigidity of the optical fiber core wire 2 including the colored layer 25 formed of the high hardness resin is preferably in the range of ^{0.88 N · mm 2 to} 1.96 N · mm ^2. When the optical fiber cable 10 is placed in a low temperature environment and contracts, and the optical fiber core wire 2 has an extra length with respect to the cable jacket 13, the optical fiber core wire 2 is locally bent and transmission loss occurs. To increase. Therefore, if the bending rigidity of the optical fiber core wire 2 is set to 0.88 N · mm ² or more, an increase in transmission loss can be suppressed even if the optical fiber core wire 2 is locally bent. Further, since bouncing the flexural rigidity of the optical fiber 2 is too high, but it becomes difficult to house the optical fiber cable 10 in the closure or cabinet, the flexural rigidity of the optical fiber 2 1.96 N · mm ² below If you do, it will be easier to store.

Further, it is desirable that the bending rigidity of the optical fiber core wire 2 and the glass fiber 21 satisfies the bending rigidity of the optical fiber core wire × 0.5 ≦ the bending rigidity of the glass fiber ≦ the bending rigidity of the optical fiber core wire × 0.8. .. If the bending rigidity of the glass fiber 21 is equal to or more than the bending rigidity of the optical fiber core wire 2 × 0.5 and within the bending rigidity of the optical fiber core wire 2 × 0.8, it can be easily stored in the closure or cabinet. Is.

Further, the relationship between the colored layer 25 of the optical fiber core wire 2 and the ES product of the glass fiber 21 (Young's modulus × cross-sectional area) is such that the ES product of the glass fiber 21 can be made larger than the ES product of the colored layer 25. preferable. More preferably, the ES product of the glass fiber 21 is larger than twice the ES product of the colored layer 25. If the glass fiber 21 is more difficult to stretch than the colored layer 25, even if the optical fiber cable 10 is placed in a low temperature environment and the colored layer 25 shrinks, it can be prevented that the glass fiber 21 is pulled by the colored layer 25 and buckles. The increase in transmission loss can be suppressed.

The torsional rigidity of the optical fiber core wire 2 is preferably in the range of ^{0.314 kN · mm 2 to} 0.686 kN · mm ^2. If the torsional rigidity of the optical fiber core wire 2 is set to 0.314 kN · mm ² or more, an increase in transmission loss can be suppressed even if the optical fiber core wire 2 is locally bent. Further, if the torsional rigidity of the optical fiber core wire 2 is set to 0.686 kN · mm ² or less, it becomes easy to store the optical fiber core wire 2.

Further, the flammability of the optical fiber core wire 2 is preferably at least equivalent to V-1 in terms of the grade based on UL94. If an inorganic material such as Hitaroid is mixed, for example, if an indirect flame of 20 mm is performed twice for 10 seconds and the combustion behavior is observed, the combustion time is 10 seconds and the flame does not burn. Therefore, the flame retardancy of the optical fiber core wire is improved.

It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present disclosure is indicated by the scope of claims, not the above-mentioned meaning, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 ... Intermittent tape core wire, 2 ... Optical fiber core wire, 3 ... Connecting part, 4 ... Non-connecting part, 5 ... Tape coating, 10 ... Optical fiber cable, 11 ... Collective core, 12 ... Press winding tape, 13 ... Cable Outer cover, 14 ... tension member, 15 ... tear string, 16 ... protrusion, 21 ... glass fiber, 22 ... primary resin layer, 23 ... secondary resin layer, 24 ... optical fiber wire, 25 ... colored layer.

Claims (5)

An optical fiber core wire composed of a glass fiber and a covering member that covers the periphery of the glass fiber.
The material of the covering member is an optical fiber core wire having a lower breaking elongation than the glass fiber. The optical fiber core wire according to claim 1, wherein the hardness of the covering member is equal to or higher than the pencil hardness H. The optical fiber core wire according to claim 1 or 2, wherein the elastic modulus of the covering member is 2.5 GPa or more. The optical fiber core wire according to any one of claims 1 to 3, wherein the coating member contains an acrylic polyol resin or a liquid crystal polymer. An optical fiber cable comprising an aggregate core in which a plurality of the optical fiber core wires according to any one of claims 1 to 4 are collected and wound by presser winding, and a cable jacket that covers the periphery of the aggregate core.

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