JP7156181B2 - fiber optic cable - Google Patents

Description

The present disclosure relates to fiber optic cables.

Patent Literature 1 describes an optical fiber cable having intermittently connected optical fiber tape core wires in a pipe.
Patent document 2 discloses an optical fiber in which a unit is mounted by winding an identification thread around the outer circumference of an optical fiber bundle in which a plurality of single coated optical fibers constituting an intermittently connected optical fiber ribbon are assembled. Cables are listed.
Patent Document 3 describes a slot rod type optical fiber cable.

Japanese Patent Application Publication No. 2015-517679 JP-A-2010-8923 JP 2014-71441 A

In the case of a structure having tensile strength members on both sides of the jacket, the optical fiber cable tends to bend in a 90-degree direction with respect to a line connecting the tensile members in a cross-sectional view, and tends to have low bending rigidity in that direction. On the other hand, the tensile strength member tends to be difficult to bend in a certain direction and have a large bending rigidity in that direction. That is, the optical fiber cable with the above structure has bending anisotropy.
If the optical fiber cable for air supply has the above structure, it has bending anisotropy, so when air is sent or pushed into the duct, it tends to bend in a direction with low bending rigidity, and there is a risk of buckling in the middle of the duct. be. For this reason, it is difficult to obtain good air-feeding characteristics with the optical fiber cable for air-feeding having the structure described above.

In many cases, optical fiber cables for pneumatic transmission have a thin cable jacket thickness to reduce the diameter and weight, and use a hard cable jacket. Therefore, it is difficult to reduce rigidity and suppress linear expansion of the cable jacket. On the other hand, in the case of an optical fiber cable such as a loose tube type or a slot rod type, in the case of a structure in which a tensile strength member with a large diameter or a bundle of a plurality of tensile strength members is arranged at the center, the volume of the tensile strength member is inside. Due to the reduced space, it is difficult to increase the core density of optical fiber cables.

SUMMARY OF THE DISCLOSURE The present disclosure aims to provide a fiber optic cable with good pneumatic delivery characteristics.

A fiber optic cable according to one aspect of the present disclosure includes:
a plurality of optical fiber core wires or a plurality of optical fiber tape core wires,
a cable sheath enclosing a plurality of said optical fiber core wires or a plurality of said optical fiber tape core wires;
Eight or more tensile strength members, which are provided so as to be embedded in the cable jacket and are paired by two,
An optical fiber cable having
The tensile strength members are provided in pairs of two at positions facing each other across the center of the optical fiber cable in a cross-sectional view,
The eight or more tensile strength members are arranged so as to include those at positions where the straight lines connecting the pairs of two each are perpendicular to each other in a cross-sectional view,
The bending rigidity in the radial direction of the optical fiber cable is 0.35 N·m ² or more and 1.3 N·m ² or less in the circumferential direction ,
A ratio of the total cross-sectional area of the tensile strength member to the cross-sectional area of the cable jacket is 5.4% or more,
The core density obtained by dividing the number of cores of the optical fiber core wires constituting the plurality of optical fiber core wires or the plurality of optical fiber ribbon core wires by the cable cross-sectional area of the optical fiber cable is 5.0 cores/mm ² or more . and
The outer diameter of the cable is 6 mm or more and 16 mm or less.

According to the present disclosure, it is possible to provide a fiber optic cable with good air-pumping characteristics.

It is a sectional view showing composition of an optical fiber cable concerning a first embodiment. FIG. 2 is a plan view showing an example of an optical fiber tape core wire accommodated in an optical fiber cable; FIG. 4 is a cross-sectional view showing the configuration of an optical fiber cable according to a second embodiment; 4 is a side view of the fiber optic cable shown in FIG. 3; FIG. It is a schematic diagram which shows a cable pumping evaluation apparatus.

(Description of Embodiments of the Present Disclosure)
First, the embodiments of the present disclosure are listed and described.
A fiber optic cable according to one aspect of the present disclosure includes:
(1) a plurality of optical fiber core wires or a plurality of optical fiber tape core wires;
a cable sheath enclosing a plurality of said optical fiber core wires or a plurality of said optical fiber tape core wires;
Eight or more tensile strength members, which are provided so as to be embedded in the cable jacket and are paired by two,
An optical fiber cable having
The tensile strength members are provided in pairs of two at positions facing each other across the center of the optical fiber cable in a cross-sectional view,
The eight or more tensile strength members are arranged so as to include those at positions where the straight lines connecting the pairs of two each are perpendicular to each other in a cross-sectional view,
The bending rigidity in the radial direction of the optical fiber cable is 0.35 N·m ² or more and 1.3 N·m ² or less in the circumferential direction ,
A ratio of the total cross-sectional area of the tensile strength member to the cross-sectional area of the cable jacket is 5.4% or more,
The core density obtained by dividing the number of cores of the optical fiber core wires constituting the plurality of optical fiber core wires or the plurality of optical fiber ribbon core wires by the cable cross-sectional area of the optical fiber cable is 5.0 cores/mm ² or more . and
The outer diameter of the cable is 6 mm or more and 16 mm or less.
According to the optical fiber cable of the above configuration, since there are eight or more tensile strength members each paired with two in a well-balanced manner, the bending anisotropy of the optical fiber cable (biased direction in which it is easy to bend) is suppressed. be able to. Therefore, it is possible to suppress buckling in the middle of the duct when the optical fiber cable is pneumatically fed or pushed into the duct, for example. Therefore, the optical fiber cable having the above configuration can obtain good air feeding characteristics. In addition, since the outer diameter of the cable is 16 mm or less, it can be accommodated in a general small microduct with an inner diameter of 20 mm or less. If the outer diameter of the cable is less than 6 mm, buckling is likely to occur when the air is fed if the microduct is bent to a small diameter. Therefore, the occurrence of buckling during air feeding can be suppressed.

According to the optical fiber cable having the above configuration, it is possible to obtain an appropriate bending rigidity suitable for pneumatic feeding by being within the above bending rigidity range. In addition, since the radial bending rigidity is 0.35 N·m ² or more in the circumferential direction, buckling during pneumatic feeding of the optical fiber cable can be suppressed. Since it is 1.3 N·m ² or less, it is easy to store the excess length of the optical fiber cable.

( 2 ) The tensile strength material may be aramid FRP.
( 3 ) The tensile strength material may be a liquid crystal polymer.
Aramid FRP and liquid crystal polymer have a relatively high modulus of elasticity, so that the cable rigidity can be moderately increased. In addition, aramid FRP and liquid crystal polymer have relatively low coefficients of linear expansion, so that shrinkage of optical fiber cables in low temperature environments can be reduced. In addition, since aramid FRP and liquid crystal polymer are non-inductive, there is no need to provide a ground for lightning protection.

( 4 ) The cable jacket may contain a silicone lubricant.
According to the optical fiber cable having the above structure, since the cable jacket contains the silicone-based lubricant, the coefficient of friction of the cable jacket can be reduced. As a result, when the optical fiber cable is pneumatically fed through the duct, the friction between the cable jacket and the duct is reduced, and the pumping distance can be extended.

( 5 ) The silicone-based lubricant contained in the cable jacket may be 3% by mass or more.
According to the optical fiber cable having the above structure, since the cable jacket contains 3% by mass or more of silicone-based lubricant, the coefficient of friction of the cable jacket can be more reliably reduced.

( 6 ) The cable jacket may have projections protruding in the radial direction of the optical fiber cable on the outer periphery.
According to the optical fiber cable having the above configuration, since the outer peripheral portion of the cable jacket has a projection projecting in the radial direction of the optical fiber cable, when the optical fiber cable is pneumatically fed in the duct, the cable jacket and the duct are separated from each other. can reduce the contact area between This reduces the friction between the cable jacket and the duct, allowing longer pumping distances.

( 7 ) The protrusion may be spirally formed along the longitudinal direction of the optical fiber cable.
According to the optical fiber cable having the above configuration, the projection is formed in a spiral shape along the longitudinal direction of the optical fiber cable, so that the inner wall of the duct and the optical fiber cable come into point contact, further reducing the contact resistance. can be reduced.

( 8 ) The cable jacket may contain flame-retardant PVC or flame-retardant polyethylene having an oxygen index of 50 or more.
Since the optical fiber cable for pneumatic transmission has a thin cable jacket, it is difficult to improve flame retardancy. Flame retardancy can be improved by using flame-retardant polyethylene.

( 9 ) The optical fiber core wire constituting the optical fiber core wire or the optical fiber ribbon core wire has a glass fiber and a coating that covers the outer periphery of the glass fiber,
The coating comprises two coating layers,
The outer coating layer of the two coating layers,
a base resin containing a urethane acrylate oligomer or urethane methacrylate oligomer, a monomer having a phenoxy group, a photopolymerization initiator and a silane coupling agent;
A cured product of a resin composition containing hydrophobic inorganic oxide particles,
A content of the inorganic oxide particles in the resin composition may be 1% by mass or more and 45% by mass or less based on the total amount of the resin composition.
According to the optical fiber cable having the above configuration, by using the resin composition as the outer coating layer constituting the coating of the optical fiber core wire, the lateral pressure resistance of the optical fiber core wire is enhanced. As a result, an increase in transmission loss of the optical fiber cable can be suppressed.

( 10 ) The optical fiber core wire constituting the optical fiber core wire or the optical fiber tape core wire has a bending loss at a wavelength of 1550 nm of 0.5 dB or less at a bending diameter of φ15 mm × 1 turn, and at a bending diameter of φ20 mm × 1 turn. It may be 0.1 dB or less.
According to the optical fiber cable having the above configuration, lateral pressure characteristics can be improved, and low-temperature loss characteristics can be improved.

(Details of embodiments of the present disclosure)
A specific example of an optical fiber cable according to an embodiment of the present disclosure will be described below with reference to the drawings.
The present invention is not limited to these exemplifications, but is indicated by the scope of the claims, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims.

(First embodiment)
An optical fiber cable 1A according to the first embodiment will be described with reference to FIGS. 1 and 2. FIG.
FIG. 1 is a cross-sectional view perpendicular to the length direction of the optical fiber cable 1A. As shown in FIG. 1, an optical fiber cable 1A includes a plurality of optical fiber tape core wires 2, a water absorbing tape 3 covering the periphery of the optical fiber tape core wires 2, and an optical fiber tape core wire covered with the water absorbing tape 3. 2, and a tensile member 5 and a tear string 6 provided inside the cable jacket 4.

The water absorbing tape 3 is wound around the entirety of the plurality of optical fiber ribbons 2, for example, vertically or horizontally. The water-absorbing tape 3 is, for example, a base fabric made of polyester or the like which has undergone water-absorbing processing by adhering water-absorbing powder thereto.

The cable sheath 4 is provided so as to cover the periphery of the water absorbing tape 3. - 特許庁The cable jacket 4 is made of resin such as polyvinyl chloride (PVC) and polyethylene (PE). The resin of the cable jacket 4 preferably has a Young's modulus of 500 Pa or more. Moreover, it is preferable that the cable jacket 4 contains a silicon-based lubricant. The silicon-based lubricant is contained, for example, at a ratio of 2 wt % or more, preferably 3 wt % or more and 5 wt % or less.

Moreover, it is preferable that the cable jacket 4 be made of a highly flame-retardant resin. The cable jacket 4 is made of, for example, flame-retardant PVC or flame-retardant polyethylene having an oxygen index of 50 or more. Thereby, the optical fiber cable 1A conforms to the UL1666 riser grade in the North American NEC (National Electrical Code) standard and the Cca class in the European CPR (Construction Products Regulation) standard. The cable jacket 4 is made of thermoplastic resin, for example, and is formed by extruding the resin onto the plurality of optical fiber tape core wires 2 around which the water absorbing tape 3 is wound.

The tensile strength member 5 is provided so as to be embedded inside the cable jacket 4 . The tensile member 5 is made of fiber reinforced plastic (FRP) such as aramid FRP, glass FRP, carbon FRP, or the like. Moreover, the tension member 5 may be formed of a liquid crystal polymer. The strength member 5 is preferably non-inductive.

The tensile strength member 5 is circular in cross section. Eight or more (eight in this example) tensile members 5 are provided. The eight tensile members 5 in this example are provided in pairs of two each. The paired two tensile members 5 are provided, for example, in close proximity to each other or in contact at least partially. The tensile member 5 is provided inside the cable jacket 4 along the longitudinal direction of the optical fiber cable 1A. In the following description, the two tensile members 5 forming a pair are collectively referred to as a tensile member unit 50 .

In this example, four tensile strength body units 50 are provided. Two pairs of four tensile strength member units 50 are provided at positions facing each other across the center of the optical fiber cable 1A in a cross-sectional view of the optical fiber cable 1A. The positions of the four tensile strength body units 50 in the cross-sectional view are positions where the two straight lines connecting the two tensile strength body units 50 forming a pair are orthogonal to each other.

For example, when the number of tensile members 5 is more than eight and the number of tensile member units 50 is greater than four, each tensile member unit 50 has an equal interval between adjacent tensile member units 50. It is provided in the cable jacket 4 so as to be spaced apart.

The tear string 6 is for tearing the cable jacket 4, and is embedded in the cable jacket 4 along the longitudinal direction of the optical fiber cable 1A. In the case of this example, two tearing strings 6 are provided. Two tearing cords 6 are provided substantially in the middle of adjacent tensile strength member units 50 so as to face each other. By pulling out the tear string 6, the cable jacket 4 is torn in the longitudinal direction, and the optical fiber ribbon 2 can be taken out. The tear string 6 is made of, for example, a plastic material (eg, polyester) that is resistant to tension.

FIG. 2 shows an example of the optical fiber ribbon 2 accommodated in the optical fiber cable 1A. As shown in FIG. 2, the optical fiber tape core wire 2 includes a connecting portion 12 in which a plurality of optical fiber core wires 11A to 11L are arranged in parallel and the adjacent optical fiber core wires are connected to each other. It is an intermittently connected optical fiber tape core wire in which non-connected portions 13 where the optical fiber core wires are not connected are intermittently provided in the longitudinal direction.

The optical fiber ribbon 2 of this example has 12 optical fibers 11A to 11L arranged in parallel. FIG. 2 shows a plan view of the intermittently connected optical fiber ribbon 2 with the optical fibers 11A to 11L opened in the arrangement direction, and a cross-sectional view of the optical fiber 11A. The locations where the connecting portions 12 and the non-connecting portions 13 are intermittently provided may be between some of the optical fibers (intermittently every two cores) as shown in FIG. It may be between optical fiber core wires (intermittent per core). In the example shown in FIG. 2, no non-connecting portion 13 is provided between the optical fibers 11A and 11B, 11C and 11D, 11E and 11F, 11G and 11H, 11I and 11J, and 11K and 11L.

The connecting portion 12 in the optical fiber tape core wire 2 is formed by applying a connecting resin 14 made of, for example, an ultraviolet curable resin, a thermosetting resin, or the like between the optical fiber core wires. By applying the connecting resin 14 between the predetermined optical fiber core wires, the connecting portion 12 and the non-connecting portion 13 are provided intermittently, and the respective optical fiber core wires 11A to 11L are integrated in a parallel state. be. The coupling resin 14 may be applied to only one surface of the parallel surfaces formed by the optical fibers 11A to 11L arranged in parallel, or may be applied to both surfaces. Further, the optical fiber tape core wire 2 is formed by, for example, applying a tape resin to one side or both sides of the optical fiber core wires 11A to 11L arranged in parallel to connect all the optical fiber core wires 11A to 11L. Alternatively, the non-connecting portion 13 may be formed by cutting a portion thereof with a rotary blade or the like.

The optical fiber core wires 11A to 11L have, for example, a glass fiber 15 composed of a core and a clad, and two coating layers 16 and 17 that coat the outer periphery of the glass fiber 15. As shown in FIG. The inner coating layer 16 of the two coating layers is made of primary resin. Outer coating layer 17 of the two coating layers is made of secondary resin. The optical fiber core wires 11A to 11L are so-called small-diameter core wires, and their outer diameter A is, for example, 165 μm or more and 220 μm or less.

A soft resin having a relatively low Young's modulus is used as a buffer layer for the primary resin that constitutes the inner coating layer 16 that contacts the glass fiber 15 . A hard resin having a relatively high Young's modulus is used as a protective layer for the secondary resin forming the outer coating layer 17 . The secondary resin has, for example, a Young's modulus at 23° C. of 900 MPa or higher, preferably 1000 MPa or higher, more preferably 1500 MPa or higher.

The secondary resin that constitutes the coating layer 17 includes a base resin containing a urethane acrylate oligomer or a urethane methacrylate oligomer, a monomer having a phenoxy group, a photopolymerization initiator and a silane coupling agent, and a hydrophobic inorganic oxide. It is preferably a resin composition containing particles. The content of the inorganic oxide particles in the resin composition is 1% by mass or more and 45% by mass or less based on the total amount of the resin composition.

Hereinafter, acrylates or their corresponding methacrylates are referred to as (meth)acrylates.

As the urethane (meth)acrylate oligomer, an oligomer obtained by reacting a polyol compound, a polyisocyanate compound and a hydroxyl group-containing (meth)acrylate compound can be used. This oligomer can be obtained, for example, by reacting polypropylene glycol with a molecular weight of 4000, isophorone diisocyanate, hydroxyethyl acrylate and methanol.

A (meth)acrylate compound having a phenoxy group can be used as the monomer having a phenoxy group. For example, the monomer having a phenoxy group is nonylphenol EO-modified acrylate (trade name “Aronix M-113” manufactured by Toagosei Co., Ltd.).

The photopolymerization initiator can be appropriately selected from known radical photopolymerization initiators and used, for example, the photopolymerization initiator is 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

The silane coupling agent is not particularly limited as long as it does not interfere with curing of the resin composition. For example, silane coupling agents include 3-mercaptopropyltrimethoxysilane.

Hydrophobic inorganic oxide particles have a hydrophobic group introduced to the surface of the inorganic oxide particles. Inorganic oxide particles are, for example, silica particles. Hydrophobic groups are reactive groups such as (meth)acryloyl groups and vinyl groups, or non-reactive groups such as hydrocarbon groups (e.g., alkyl groups) and aryl groups (e.g., phenyl groups). good.

By adding the inorganic oxide particles to the secondary resin that forms the coating layer 17, the lateral pressure characteristics of the optical fiber core wires 11A to 11L are improved. The primary resin and the secondary resin forming the coating layer 16 are made of, for example, an ultraviolet curable resin, a thermosetting resin, or the like.

The optical fiber tape core wires 2 are rolled and collected when they are accommodated in the optical fiber cable 1A. Alternatively, a plurality of optical fiber tape core wires 2 may be twisted together to form a unit, and the plurality of units may be assembled. The bundled optical fiber ribbons 2 may be bundled with a bundle material or the like, or may be bundled with a bundle material for each unit.

In the optical fiber cable 1A configured as described above, the ratio of the total cross-sectional area of the eight tensile strength members 5 (four tensile strength member units 50) to the cross-sectional area of the cable jacket 4 is 5.4% or more. is preferred. The outer diameter of the optical fiber cable 1A is 6 mm or more and 16 mm or less. If eight 0.5 mm tensile members 5 are provided, the ratio of the total cross-sectional area is 5.6%. The radial bending rigidity of the optical fiber cable 1A is preferably 0.35 N·m ² or more and 1.3 N·m ² or less in the circumferential direction.

Further, the core density obtained by dividing the number of cores of all the optical fibers constituting the plurality of optical fiber tape core wires 2 by the cable cross-sectional area of the optical fiber cable 1A is preferably 5.0 cores/mm ² or more. . For example, when the outer diameter of the optical fiber cable 1A is 10 mm, the thickness of the cable jacket 4 is 1.0 mm, and the outer diameter A of the optical fiber core wire is 200 μm, the inside of the cable jacket 4 of the optical fiber cable 1A If the number of 12-core optical fiber tape core wires 2 housed in the container is 36, the total number of optical fiber core wires at that time is 432 cores, and the core density is 5.5 cores/mm ² . Become. In consideration of pneumatic feeding, the unit weight of the optical fiber cable 1A is desirably 100 kg/km or less.

In this example, the optical fiber ribbon 2 with 12 cores is used, but an optical fiber ribbon with 16 cores or 24 cores, for example, may be used. Further, in this example, the optical fiber tape core wire is accommodated in the optical fiber cable 1A, but the optical fiber cable core wire may be accommodated as it is without being tape-shaped. In addition, the optical fibers 11A to 11L have a bending loss of 0.5 dB or less at a wavelength of 1550 nm with a bending diameter of φ15 mm×1 turn, and a bending loss of 0.1 dB or lower with a bending diameter of φ20 mm×1 turn. A bending loss equivalent to 657A2 is preferable. By using such an optical fiber core wire, lateral pressure characteristics can be improved, and low-temperature loss characteristics can be improved.

As described above, according to the optical fiber cable 1A according to the first embodiment, the tensile strength member units 50, each of which is composed of two pairs of the tensile strength members 5, are arranged inside the cable sheath 4 in a well-balanced manner. Therefore, it is possible to suppress the bending anisotropy of the optical fiber cable 1A (bias in the easy-to-bend direction).
Thereby, it is possible to suppress buckling in the middle of the duct when the optical fiber cable 1A is air-fed or pushed in the duct, for example. Therefore, the optical fiber cable 1A can have good air feeding characteristics.

In addition, since the outer diameter of the optical fiber cable 1A is 16 mm or less, the optical fiber cable 1A can be pneumatically fed into a small microduct having an inner diameter of 20 mm or less and accommodated in the microduct.

When the cable outer diameter of the optical fiber cable is less than 6 mm, buckling of the optical fiber cable is likely to occur when the optical fiber cable is air-fed if the duct is laid with a small diameter bend. On the other hand, since the optical fiber cable 1A has a cable outer diameter of 6 mm or more, it is possible to suppress the occurrence of buckling during air feeding.

In addition, the optical fiber cable 1A has a radial bending rigidity in the range of 0.35 N·m ² or more and 1.3 N·m ² or less in the circumferential direction, thereby providing an appropriate bending rigidity suitable for pneumatic feeding. be prepared. For example, since the bending rigidity in the radial direction is 0.35 N·m ² or more in the circumferential direction, it is possible to suppress the occurrence of buckling when the optical fiber cable 1A is pneumatically fed. In addition, since the bending rigidity in the radial direction is 1.3 N·m ² or less in the circumferential direction, when the excess length of the optical fiber cable 1A is stored in a hand hole or the like, the optical fiber cable 1A can be placed in an appropriate size. It is possible to bundle it into a bundle and it is easy to store.

In addition, it is preferable that the tensile member 5 of the optical fiber cable 1A is made of, for example, aramid FRP, liquid crystal polymer, or the like. According to this configuration, since aramid FRP, liquid crystal polymer, etc. have a relatively high elastic modulus, the rigidity of the optical fiber cable 1A can be moderately increased. In addition, since aramid FRP, liquid crystal polymer, etc. have a relatively low coefficient of linear expansion, shrinkage of the optical fiber cable 1A due to shrinkage of the cable jacket 4 under low temperature environments can be suppressed. Also, since aramid FRP, liquid crystal polymer, etc. are non-inductive, there is no need to provide a ground for lightning countermeasures.

In addition, it is preferable that the resin of the cable jacket 4 of the optical fiber cable 1A contains a silicone-based lubricant. With this configuration, the coefficient of friction of the cable jacket 4 can be reduced. Furthermore, by setting the silicon-based lubricant contained in the cable jacket 4 to 3% by mass or more, the coefficient of friction of the cable jacket 4 can be lowered more reliably. As a result, when the optical fiber cable 1A is pneumatically fed through the duct, the friction between the cable jacket 4 and the inner wall of the duct can be reduced, and the pumping distance can be extended.

By the way, since the optical fiber cable for pneumatic transmission has a structure in which the cable jacket is thin, it is difficult to improve the flame resistance. On the other hand, in the optical fiber cable 1A, the cable jacket 4 is made of flame-retardant PVC or flame-retardant polyethylene having an oxygen index of 50 or more, thereby enhancing flame retardancy.

Further, according to the optical fiber cable 1A, by using the above-mentioned cured resin composition as the outer coating layer 17 constituting the coating of the optical fiber core wires 11A to 11L, the optical fiber core wires 11A to 11L can be Side pressure resistance can be strengthened. Therefore, if the optical fiber tape core wire 2 is configured using such optical fiber core wires 11A to 11L, it is possible to suppress an increase in transmission loss when accommodated in the optical fiber cable 1A.

(Second embodiment)
An optical fiber cable 1B according to the second embodiment will be described with reference to FIGS. 3 and 4. FIG. In addition, the same code|symbol is attached|subjected about the structure similar to 1 A of optical fiber cables which concern on 1st embodiment, and the description is abbreviate|omitted.

FIG. 3 is a cross-sectional view perpendicular to the longitudinal direction of the optical fiber cable 1B. 4 is a side view of the optical fiber cable 1B shown in FIG. 3. FIG.
As shown in FIG. 3, the optical fiber cable 1B includes a plurality of intermittently connected optical fiber ribbons 2, a water absorption tape 3 covering the optical fiber ribbons 2, and a light cable covered with the water absorption tape 3. It comprises a cable sheath 4 enclosing a fiber tape core wire 2, and a tensile strength member 5 and a tear string 6 provided inside the cable sheath 4. - 特許庁Furthermore, the optical fiber cable 1B has projections 7 on the outer peripheral portion of the cable sheath 4. As shown in FIG.

A plurality of projections 7 (eight in this example) are provided. As shown in FIG. 4, the eight protrusions 7 are spirally provided along the longitudinal direction of the optical fiber cable 1B. Each protrusion 7 may be provided continuously along the longitudinal direction, or may be provided intermittently. Further, the eight protrusions 7 are provided at approximately equal intervals in the circumferential direction of the outer peripheral portion of the cable jacket 4 in a cross-sectional view. The protrusion 7 is formed on the outer peripheral portion of the cable jacket 4 in a state of protruding in the radial direction of the optical fiber cable 1B. The protrusion 7 has a curved end surface 7a in the projecting direction, and the radius of curvature of the curved surface is 2.5 mm or more. The protrusions 7 are integrally formed with the cable jacket 4 by extrusion. In this example, the eight projections 7 are spirally provided, but may be linearly provided along the longitudinal direction of the optical fiber cable 1B, for example.

According to the optical fiber cable 1B according to the second embodiment, a plurality of protrusions 7 projecting in the radial direction of the optical fiber cable 1B are provided on the outer peripheral portion of the cable jacket 4. As shown in FIG. Therefore, when the optical fiber cable 1B is pneumatically fed through the duct, the protrusion 7 comes into contact with the inner wall of the duct, so the contact area between the cable jacket 4 and the duct can be reduced. As a result, the friction between the cable jacket 4 and the duct is reduced, and the pumping distance can be extended.

Further, according to the optical fiber cable 1B, the protrusion 7 of the cable jacket 4 is formed in a spiral shape along the longitudinal direction of the optical fiber cable 1B. As a result, when air is fed in the duct, the inner wall of the duct and the cable jacket 4 of the optical fiber cable 1B are in a state close to point contact. Therefore, the friction between the two can be further reduced, and the pumping distance can be extended.

(Example)
In the optical fiber cables 1A and 1B according to the embodiment of the present disclosure, the optical fiber cable samples of each example in which the type and number of the tensile members 5 and the structure of the cable jacket 4 are different, and each comparative example of the conventional structure The pumping distance was evaluated for the optical fiber cable samples. Table 1 shows the evaluation results.

In Table 1, sample no. 1 to 3 are comparative examples. Sample no. Sample No. 1 is an optical fiber cable having a structure in which two tensile members are embedded in the cable jacket. 2 and 3 are optical fiber cables having a structure in which four tension members are embedded in the cable jacket. Sample no. 4 to 8 and 11 are those in which eight tensile members are embedded in the cable sheath so that two each are in pairs, and correspond to the first embodiment. Sample no. Reference numerals 9 and 10 have eight tensile strength members embedded in the cable jacket so that two of each are embedded in pairs, and a projection is provided on the outer peripheral portion of the cable jacket, which corresponds to the second embodiment. is. In addition, sample No. 9, the projection 7 is formed linearly along the longitudinal direction of the optical fiber cable 1B. Sample no. 10, as shown in FIG. 4, a projection 7 is formed spirally along the longitudinal direction of the optical fiber cable 1B.
Also, sample no. Tensile members 1, 2 and 4 are glass FRP with an outer diameter of 0.5 mm. Sample no. The 3,5-10 strength members are aramid FRP with an outer diameter of 0.5 mm. Sample no. 11 is a liquid crystal polymer with an outer diameter of 0.5 mm.
Also, sample no. Sample No. 6 is obtained by adding 2 wt % of silicone lubricant to the cable jacket. 7, 9 and 10 are samples with 3 wt % added. 8 and 11 are added at 5 wt %.
Moreover, the cable outer diameter of each sample is 10 mm.

The maximum and minimum bending stiffness indicate the bending stiffness value in the direction of maximum bending stiffness and the bending stiffness value in the direction of minimum bending stiffness when each optical fiber cable is bent in the radial direction. The bending stiffness measurement method complies with IEC60794 Stiffness (Method E17A). In the case of the structure shown in FIG. 1, for example, the bending stiffness becomes the maximum value when bending in the direction of the tensile member 5, and becomes the minimum value when bending in the direction deviated from the direction of the tensile member 5 by 45 degrees.
The coefficient of dynamic friction indicates the coefficient of friction between the optical fiber cable pneumatically fed through the duct and the inner wall of the duct.
As for the pumping distance, a pumping test conforming to IEC was performed using the pumping device shown in FIG. The pipe 20 has a length of 1000m and is folded back every 100m. The bend (R) of the pipe 20 is 40 times the outer diameter of the pipe, and the inner diameter of the pipe 20 is 14 mm. Aperture 21 is the inlet for air and fiber optic cable, and aperture 22 is the outlet for air and fiber optic cable. The air pressure was 1.3 MPa to 1.5 MPa.

The pumping distance is evaluated as S when the pumping distance is 1800 m or more, A when the pumping distance is 1300 m or more and less than 1800 m, B when the pumping distance is 800 m or more and less than 1300 m, and less than 800 m. was evaluated as C.

According to the evaluation results in Table 1, No. 2 samples (samples rated S) with a pumping distance of 1800 m or more. No. 7 to 11, and the sample with a pumping distance of 1300 m or more and less than 1800 m (evaluation A sample). It was 4-6. On the other hand, the sample (evaluation B sample) with a pumping distance of 800 m or more and less than 1300 m was No. 2 and 3, and the sample with a pumping distance of less than 800 m (evaluation C sample) is No. was 1. As a result, it was found that, in an optical fiber cable, by embedding a total of 8 tensile strength members in pairs of 2 in the cable jacket, the pumping distance can be increased to 1300 m or more.

In addition, No. 1 is the sample with a pumping distance of 1800 m or more (sample of evaluation S). Since it is 7 to 11, when 3 wt% or more of silicone lubricant is added to the cable jacket, the dynamic friction coefficient can be reduced to about 1/3 compared to the case where silicone lubricant is not added, and the pumping distance can be greatly extended. I found out. However, when 5 wt% of silicone lubricant is added, the outer sheath of the cable becomes slightly softer, so the flexural rigidity is lower than when 3 wt% of silicone lubricant is added, and the elongation rate of the pumping distance becomes gentler. Do you get it. Further, if the silicon-based lubricant is added in an amount exceeding 5 wt %, the optical fiber cable may collapse due to winding, etc., resulting in poor handling. From this, it was found that the addition ratio of the silicon-based lubricant is preferably 3 wt % or more and 5 wt % or less.

Also, sample no. 9 and 10, it was found that the pumping distance can be increased to 1900 m or more by providing the cable jacket with projections. Furthermore, it has been found that the pumping distance can be extended up to 2000 m by making the projection spiral along the longitudinal direction of the optical fiber cable.

Also, in order to further improve the characteristics of the optical fiber cable, the secondary resin of the optical fiber core wires 11A to 11L was examined. As a result, by blending the inorganic oxide particles into the secondary resin, the lateral pressure characteristics of the optical fiber ribbon can be improved, and the core density can be increased by about 1.0 to 1.5 cores/mm ² . Do you get it.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. Further, the number, positions, shapes, etc. of the constituent members described above are not limited to those in the above-described embodiment, and can be changed to suitable numbers, positions, shapes, etc. in carrying out the present invention.

1A, 1B: optical fiber cable 2: optical fiber tape core wire 3: water absorbing tape 4: cable jacket 5: tensile strength member 6: tear string 7: protrusion 7a: end surface 11A to 11L: optical fiber core wire 12: connecting part 13 : non-connecting part 14: connecting resin 15: glass fiber 16: inner coating layer 17: outer coating layer 20: pipe 21, 22: opening 50: strength unit

Claims (10)

a plurality of optical fiber core wires or a plurality of optical fiber tape core wires,
a cable sheath enclosing a plurality of said optical fiber core wires or a plurality of said optical fiber tape core wires;
Eight or more tensile strength members, which are provided so as to be embedded in the cable jacket and are paired by two,
An optical fiber cable having
The tensile strength members are provided in pairs of two at positions facing each other across the center of the optical fiber cable in a cross-sectional view,
The eight or more tensile strength members are arranged so as to include those at positions where the straight lines connecting the pairs of two each are perpendicular to each other in a cross-sectional view,
The bending rigidity in the radial direction of the optical fiber cable is 0.35 N·m ² or more and 1.3 N·m ² or less in the circumferential direction ,
A ratio of the total cross-sectional area of the tensile strength member to the cross-sectional area of the cable jacket is 5.4% or more,
The core density obtained by dividing the number of cores of the optical fiber core wires constituting the plurality of optical fiber core wires or the plurality of optical fiber ribbon core wires by the cable cross-sectional area of the optical fiber cable is 5.0 cores/mm ² or more . and
The outer diameter of the cable is 6 mm or more and 16 mm or less,
fiber optic cable. The tensile strength body is aramid FRP,
The optical fiber cable of Claim 1 . The tensile strength body is a liquid crystal polymer,
The optical fiber cable of Claim 1 . The cable jacket contains a silicone-based lubricant,
The optical fiber cable according to any one of claims 1-3 . The silicon-based lubricant contained in the cable jacket is 3% by mass or more,
The optical fiber cable according to claim 4 . The cable jacket has a projection projecting in the radial direction of the optical fiber cable on the outer peripheral part,
The optical fiber cable according to any one of claims 1-5 . The protrusion is spirally formed along the longitudinal direction of the optical fiber cable,
The optical fiber cable according to claim 6 . The cable jacket contains flame-retardant PVC or flame-retardant polyethylene having an oxygen index of 50 or more,
The optical fiber cable according to any one of claims 1-7 . The optical fiber core wire constituting the optical fiber core wire or the optical fiber tape core wire has a glass fiber and a coating that covers the outer periphery of the glass fiber,
The coating comprises two coating layers,
The outer coating layer of the two coating layers,
a base resin containing a urethane acrylate oligomer or urethane methacrylate oligomer, a monomer having a phenoxy group, a photopolymerization initiator and a silane coupling agent;
A cured product of a resin composition containing hydrophobic inorganic oxide particles,
The content of the inorganic oxide particles in the resin composition is 1% by mass or more and 45% by mass or less based on the total amount of the resin composition.
The optical fiber cable according to any one of claims 1-8 . The optical fiber core wire constituting the optical fiber core wire or the optical fiber ribbon core wire has a bending loss at a wavelength of 1550 nm of 0.5 dB or less with a bending diameter of φ15 mm×1 turn, and 0.1 dB with a bending diameter of φ20 mm×1 turn. is the following
10. The optical fiber cable according to any one of claims 1-9 .

Images