JP2009181119A - Optical cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical cable that has a structure for implementing improved durability. <P>SOLUTION: The optical cable 10 basically comprises a coated optical fiber 11 and a cable jacket 16 covering an outer circumference of the coated optical fiber. The coated optical fiber 11 comprises a glass fiber 12 and a coating layer 13 of an ultraviolet-curable resin. For implementing an excellent impact resistance as an aspect of durability, the coating layer 13 of the coated optical fiber includes a first coating 13b having a Young's modulus of 200 Mpa or more. Meanwhile, the cable jacket 16 is composed of a halogen-free thermoplastic resin. The cable jacket 16 has a thickness of 0.7 mm or more, a flame resistance rated V2 of UL standards or higher, and the same or greater Young's modulus than the first coating 13b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical cable applicable to optical LAN wiring or the like for connecting information devices.

  With recent advances in optical communication technology, LAN (Local Area Network) wiring for optical communication, wiring between devices, and the like have been adopted. Optical cables used for indoor and in-vehicle optical LAN wiring, optical wiring between devices, etc. are flexible and have a small diameter in consideration of use in special environments with intricate parts and irregularities. It is desirable to be.

  The optical cable used in the special environment as described above is relatively short (1 m to 20 m) as compared with a normal optical cable (optical cable for long-distance communication). Therefore, such a short optical cable is not required to have a transmission loss as low as that of a normal optical cable. On the other hand, in the case of an optical cable used in a special environment, a flame retardant of 30% or more by weight ratio is often put in the cable jacket. This is because if the outer dimensions of the optical cable are small, the surface area per unit volume will be large and it will be easy to touch the air, and it is necessary to use a halogen-free flame retardant with low flame retardancy due to environmental problems. .

  Optical LAN wiring, inter-device wiring, and the like are used for short-distance optical communication between devices installed in a special environment such as indoors and vehicles, unlike long-distance optical communication. Therefore, a multimode optical fiber having a large core diameter, which is superior in optical connectivity as compared to a single mode optical fiber, is often applied to an optical cable premised on use in a special environment. However, multimode optical fibers are subject to disturbance factors such as temperature expansion and contraction, and transmission loss is likely to increase compared to general-purpose single mode optical fibers. Therefore, a soft ultraviolet curable acrylate resin (soft layer) having a Young's modulus of about 1 MPa is used for the coating layer of the optical fiber core wire so that the disturbance factor can be reduced.

  An optical cable having a shape known as a drop cable or an indoor cable is known as an optical cable having a relatively small number of optical fiber cores and a small cable outer dimension (for example, see Patent Document 1). In this type of optical cable, tension members are usually disposed on both sides of one to several optical fiber cores, and these optical fiber core wires and tension members are integrally covered with a cable jacket made of a thermoplastic resin. Yes. Further, in Patent Document 1 described above, an optical cable is provided with impact resistance characteristics and side pressure resistance characteristics by arranging a fibrous interposition around the optical fiber core wire.

  Furthermore, optical cables used in special environments such as indoors and vehicles are required to have high bending performance as wiring in complicated places and wiring at door opening and closing parts. In addition, the connection to the equipment is generally performed using an optical connector, but the optical connector may be installed in the field, or even if the manufacturer attaches the optical connector to the optical cable in advance. Therefore, there is a demand for an optical cable excellent in mountability of the optical connector.

Conventionally, as a drop optical cable or an indoor optical cable, for example, as shown in FIG. 14 (a), tension members 3 made of steel wires having a diameter of about 0.4 mm are arranged on both sides of the optical fiber core wire 2, and these optical fibers are arranged. A cable structure in which the fiber core wire 2 and the tension member 3 are integrally covered with a cable jacket 4 so that the cable outer diameter is about 2 to 4 mm is known (see, for example, Patent Document 2). Further, as shown in FIG. 14B, a stranded steel wire obtained by twisting a plurality of thin steel wires is known as the tension member 3. Furthermore, as a structure of the tension member 3, a structure in which glass fibers, aramid fibers or the like are integrated with resin instead of steel wires is also known.
JP 2004-144821 A JP 2004-198588 A

  As a result of examining the conventional optical cable, the inventors have found the following problems. That is, for an optical cable applied to a LAN or inter-device wiring, a situation where a small work tool such as a nipper is dropped at a place where a convex portion is located under the optical cable is assumed. Therefore, an optical cable that is assumed to be used in a special environment is required to have durability that can withstand such an impact. However, if the outer dimension of the optical cable is small, the thickness of the cable jacket that protects the optical cable is also reduced, so that the impact resistance is reduced. In addition, the non-halogen flame retardant added to the cable jacket in order to increase the flame retardancy, the more easily the cable jacket is plastically deformed as the amount added is increased. In this case, when an impact is applied, the cable jacket is crushed like clay, and the optical fiber core covered with the cable jacket is easily damaged. In this specification, “damage of the optical fiber core wire” means peeling of the interface between the glass portion and the resin coating, cracking of the resin coating, or the like.

  In addition, when a low Young's modulus resin (such as an acrylate resin layer with a low Young's modulus) is applied as the coating layer for the optical fiber core, the transmission characteristics of the optical fiber will be good, but it will be coated when subjected to external impacts. The layer itself collapses. Along with this, a large strain also occurs in the colored layer located on the surface of the coating layer of the optical fiber core wire. Since the colored layer does not easily transmit ultraviolet rays due to the addition of a colorant, a large amount of a crosslinking component having a low elongation at break is added to accelerate curing. As a result, the elongation at break is as low as about 2%, so that the colored layer itself is damaged beyond the limit of the elongation at break.

  Furthermore, in an optical cable having a small number of optical fiber cores and a small outer dimension as described above, when an impact is applied, the cable jacket is liable to be crushed, and the coating layer of the optical fiber core wire is likely to be damaged. When the cable jacket is crushed, the portion tends to be a starting point of bending, and the optical cable itself may be bent at an allowable bending diameter or less. In addition, regarding the damage of the optical fiber core, there is a fear that the fiber glass may be broken under an environment where temperature change or vibration is applied for a long time, and there is anxiety in terms of long-term reliability.

  Here, as disclosed in Patent Document 1, it is possible to improve the impact resistance by covering the periphery of the optical fiber with a fibrous inclusion. However, optical cables applied to LANs and wiring between devices are usually used with optical connectors attached, and if fiber-like inclusions are present, there are problems such as reducing the workability of connector attachment. is there. It is also possible to improve the impact resistance of the optical cable by increasing the thickness of the cable jacket. However, in this case, the outer dimensions of the optical cable are increased. Therefore, there is a problem that the wiring space is increased, the cable bending rigidity is increased, and the handling property of the optical cable itself is deteriorated.

  In addition, when the optical cable is used in an opening / closing part such as a door, the optical cable is required to have high bending performance. For example, there is a demand for durability that does not damage the optical cable even if it is bent 100,000 times or more at a bending radius R9 mm and 90 ° left and right. Accordingly, as shown in FIG. 14 (a), when a single-core steel wire is applied as a tension member, if it is bent at a bending radius of R9 mm and a right and left angle of 90 °, metal fatigue occurs in about 2000 times. (Tension member disconnection). Further, as shown in FIG. 14B, even when a twisted steel wire is applied as the tension member, the tension member is disconnected about 10,000 times. That is, when a metal wire is included in the optical cable, it is difficult to ensure the above bending performance.

  It is also known to use a non-metallic material in which a high-strength glass fiber material or an aramid fiber material is integrally hardened with a resin as a tension member of an optical cable. However, such a tension member made of a non-metallic material may be broken when bent at a bending radius of about R9 mm, and the tensile strength is lowered even if it is not completely broken like a metal wire. If a high-strength fiber material is used as the tension member without being hardened with a resin, it takes time to process the fiber material when attaching the optical connector to the end of the optical cable, and there is a problem that workability is reduced.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an optical cable having a structure for improving durability as compared with a conventional optical cable. In this specification, the endurance performance of an optical cable means resistance (quality maintenance performance) to environmental changes such as heat, vibration, and impact, and shape changes (bending, stretching, etc.). For example, impact resistance and bending Expressed in terms of performance.

  The optical cable according to the present invention includes, as a basic structure, an optical fiber core (coated optical fiber) and a cable jacket that covers the outer periphery of the optical fiber core wire. The optical fiber core has a bare glass fiber mainly composed of quartz glass, and a coating layer provided on the outer periphery of the bare fiber and made of an ultraviolet curable resin.

  In the optical cable according to the present invention, the coating layer of the optical fiber core includes a first coating (hard layer) having a Young's modulus of 200 MPa or more in order to achieve excellent impact resistance as durability performance. On the other hand, the cable jacket is made of a thermoplastic resin containing no halogen. The cable jacket has a thickness of 0.7 mm or more, flame retardancy of V2 or more according to UL standards, and Young's modulus equal to or higher than that of the first coating. The cable jacket covers the optical fiber core wire so that the cross-sectional shape of the optical cable becomes a circle other than a rectangle or an ellipse.

  In the optical cable according to the present invention having the above-described structure, the covering layer may have various structures. For example, the coating layer having a Young's modulus of 700 MPa or more may have a single layer structure in which the first coating is in direct contact with the surface of the bare fiber. In addition to the first coating, the coating layer may have a multilayer structure including a second coating (soft layer) provided between the bare fiber and the first coating. In the case of such a multilayer structure, the second coating preferably has a Young's modulus of 0.5 to 2 MPa.

  The optical cable according to the present invention may further include a colored layer provided on the outer periphery of the optical fiber core wire. The cable jacket integrally covers the optical fiber core wire together with the colored layer. In this case, the colored layer preferably has a breaking elongation of 10% or more. In the structure in which the colored layer is not provided, the cable jacket covers the optical fiber core wire in a state of being in direct contact with the optical fiber core wire.

  Furthermore, the optical cable according to the present invention may include a protective layer provided on the outer periphery of the colored layer. In this case, the protective layer is preferably made of an ultraviolet curable resin having a Young's modulus of 50 to 300 MPa.

  On the other hand, in the optical cable according to the present invention, it is preferable that the cable jacket does not include a metal wire in the inside in order to realize bending performance excellent as durability performance. The cable jacket preferably has a tensile tension of 50 N or more when stretched by 1% along the longitudinal direction of the optical cable. The optical cable according to the present invention may further include a connecting component attached to the cable jacket so as to be positioned at the end of the optical cable as an optical connector. In this case, the cable jacket is integrated with the optical fiber core so that the total tensile tension of the optical cable when the optical cable is extended by 1% along the longitudinal direction is 50 N or more. preferable. Here, the “total tensile tension of the optical cable” means the tensile tension when the optical cable is stretched by 1% along the longitudinal direction in a state where the cable jacket is held, and is integrated with the cable jacket. The tensile tension of a member such as an optical fiber core wire is also taken into consideration. The cable jacket covers the optical fiber core wire so that the cross-sectional shape of the optical cable becomes a circle other than a rectangle or an ellipse. The maximum outer diameter of the cable jacket is preferably 4 mm or less.

  In order to realize excellent bending performance, the optical cable according to the present invention can be variously modified. For example, the optical cable may not include an anti-shrink member. In this case, it is preferable that the surface of the bare optical fiber is coated with a resin having a Young's modulus of 0.1 MPa to 10 MPa.

  The optical cable may not include a tension member. In this case, the cable jacket is preferably made of a thermoplastic resin having a Young's modulus of 200 to 1500 MPa.

  Furthermore, in the optical cable according to the present invention, the high-strength fiber bundle is covered with the cable jacket integrally with the optical fiber core in a state where the high-strength fiber bundle is disposed on both sides of the optical fiber core along the optical fiber core. May be. In this case, it is preferable that the high-strength fiber bundle covered with the cable jacket is covered with the cable jacket at a density at which the force for pulling out the high-strength fiber bundle from the cable jacket is 50 N / cm to 900 N / cm.

  On both sides of the optical fiber core wire, a rod-shaped wire material in which a high-strength fiber bundle is hardened with a matrix resin may be disposed. These optical fiber core wire and rod-shaped wire are integrally covered with a cable jacket. Moreover, it is preferable that the thickness of the rod-shaped wire rod in a direction orthogonal to the arrangement direction with the optical fiber core wire is a thickness that can withstand a predetermined bending test.

  The bending test is performed by measuring the total tensile tension of the cable jacket after bending 100,000 times under the condition of a radius of curvature of 9 mm and a right and left of 90 °. The tensile tension required for good bending performance is 50 N or more when the cable jacket is stretched by 1% along its longitudinal direction.

  Furthermore, the high-strength fiber bundle disposed in the cable jacket as the tension member may have conductivity.

  Each embodiment according to the present invention can be more fully understood from the following detailed description and the accompanying drawings. These embodiments are shown merely for illustrative purposes and should not be considered as limiting the invention.

  Further scope of applicability of the present invention will become apparent from the detailed description given below. However, the detailed description and specific examples, while indicating the preferred embodiment of the invention, are presented for purposes of illustration only and various modifications and improvements within the scope of the invention may It will be apparent to those skilled in the art from the detailed description.

  According to the present invention, by ensuring the elasticity of the cable jacket, it is possible to obtain impact characteristics that are excellent as durability performance. That is, the crushing of the cable jacket can be suppressed to a predetermined value or less, and it is possible to reduce the possibility that the impacted portion is easily bent. Further, by forming the coating layer of the optical fiber core with the resin material having the above-described characteristics, damage to the colored layer having a small elongation at break is reduced, and the bare fiber (glass fiber) contained in the optical fiber core is reduced. Can be prevented from breaking, and long-term reliability can be improved.

  In addition, according to the present invention, it has a tensile tension that can sufficiently withstand the tension that is temporarily applied when laying the optical cable, and does not break in a bending test of 100,000 times under the condition of a radius of curvature of R9 mm and 90 ° left and right, Furthermore, an optical cable suitable for LAN wiring having excellent workability when attaching the optical connector can be obtained.

  Hereinafter, embodiments of the optical cable according to the present invention will be described in detail with reference to FIGS. In the description of the drawings, the same portions and the same elements are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
First, a first embodiment of an optical cable according to the present invention will be described in detail with reference to FIGS. FIG. 1 is a view for explaining a first embodiment of an optical cable according to the present invention. In particular, FIG. 1 (a) shows a basic structure (cross-sectional structure) of the optical cable, and FIG. 1 (b) shows the optical cable. The figure for demonstrating the test method of the impact resistance of is shown. 1A, an optical cable 10 includes an optical fiber core wire 11, tension members 17 disposed on both sides of the optical fiber core wire 11 along the optical fiber core wire 11, an optical fiber core wire 11 and a tension. A cable jacket 16 that integrally covers the member 17 is provided. The optical fiber core 11 includes a bare fiber (glass fiber) 12, a coating layer 13 provided on the outer periphery of the glass fiber 12, and a colored layer 14 provided on the surface of the coating layer 13. The glass fiber 12 includes a core having a predetermined refractive index extending along a predetermined axis on the surface, and a clad having a lower refractive index than the core provided on the outer periphery of the core. The coating layer 13 may have a multilayer structure composed of a primary coating 13a (corresponding to a soft layer ... second coating) and a secondary coating 13b (corresponding to a hard layer ... corresponding to the first coating), It may be a single layer structure. As shown in FIG. 1B, the impact test of the optical cable 10 is performed by dropping a weight 19 on a part of the optical cable 10 placed on the metal piece 18.

  The optical cable 10 according to the first embodiment is an optical cable for optically connecting a plurality of information devices installed indoors or in a vehicle, and is relatively short (for example, about 1 m to 20 m). . Specifically, the optical cable 10 is applied to, for example, LAN construction using optical communication (LAN optical cable). In this type of optical cable 10, for example, as shown in FIG. 1A, two or more optical fiber cores 11 are arranged in a line, and tension members 17 are arranged on both sides thereof (tension members 17 The optical fiber core wire 11 and the tension member 17 are integrally covered with the cable jacket 16.

  As the glass fiber 12 of the optical fiber core 11, a multimode glass fiber 12 made of quartz glass, having a core diameter of 50 μm and a cladding diameter of 125 μm is applicable. In addition, the optical fiber mainly made of quartz glass may be one in which both the core and the clad are made of quartz glass, or only the core is made of quartz glass and the clad is made of hard plastic. There may be.

  The optical fiber core wire 11 is provided on the surface of the coating layer 13b when the glass fiber 12 and the coating layers 13a and 13b coated on the surface of the glass fiber 12 (having an outer diameter of about 245 μm made of an ultraviolet curable acrylate resin). The coating layer preferably has a two-layer structure of a primary coating 13a (soft layer) and a secondary coating 13b (hard layer), in which case the Young's modulus of the inner primary coating 13a is set to the outer side. By making it smaller than the Young's modulus of the secondary coating 13b, it is possible to give a buffering function against the lateral pressure to the optical fiber core 11. Accordingly, the optical fiber core 11 having such a multi-layered coating layer 13 has a micro-structure. Generation of bends can be effectively suppressed and good optical transmission characteristics can be maintained.

  In the optical cable 10 according to the first embodiment, two or more optical fiber cores 11 are disposed side by side, tension members 17 are disposed at both ends thereof, and the optical fiber core wires 11 and the tension members 17 are further disposed. Are integrally covered with the cable jacket 16 to obtain the optical fiber core 10. The tension member 17 may not be arranged. In other words, the tension member 17 may not be particularly required in a usage mode in which a large tension is not always applied as in the case of LAN wiring, as long as the tensile tension of the entire optical cable can be secured to a predetermined value or more. However, by arranging the tension member 17 in the cable jacket 16, the tension applied to the optical fiber core wire 11 in the laying operation or the like can be effectively reduced. Here, a high-strength polymer fiber bundle such as a metal wire or an aramid fiber can be applied to the tension member 17. Further, the high-strength polymer fiber bundle may be used in the form of a rod-shaped wire solidified with a matrix resin.

  The cable jacket 16 is made of a thermoplastic resin such as nylon resin or polyethylene, and as shown in FIG. 1A, in the cross section of the optical cable 10, the arrangement direction of the optical fiber core wires 11 is the long side. The optical fiber core wire 11 is covered so as to have a rectangular or elliptical shape. The coating thickness (minimum thickness of the cable jacket 16) on the short side (the direction perpendicular to the arrangement of the optical fiber cores 11) of the cable jacket 16 is 0.7 mm or more. In addition, it is preferable that the outer diameter on the long side in the cross section of the cable jacket 16 (the maximum outer diameter of the cable jacket 16) is 4 mm or less. In addition, as the thermoplastic resin of the cable jacket 16, a halogen-free resin having flame retardancy of V2 according to UL standards is employed. In addition, various types of resins such as styrene, olefin, polyester, and urethane can be used for the cable jacket 16. The cable jacket 16 is formed by full extrusion.

  Solid extrusion is a method of performing extrusion while applying pressure to the optical fiber core 11 or the like so as to compress the extruded resin inside the die of the resin extruder. The extruded resin is in a compressed state in the die, and the thermoplastic resin extruded on the outer periphery of the optical fiber core wire 11 can have high adhesion to the optical fiber core wire 11 as the cable jacket 16. it can. Since the cable jacket 16 is in close contact with the optical fiber core 11, it is possible to prevent the optical fiber core 11 from meandering in the cable when the cable jacket 16 contracts.

  In the optical cable according to the present invention, the cable jacket 16 is made of an elastic thermoplastic resin having a Young's modulus of 200 MPa or more in order to provide impact resistance as durability performance. Further, the cable jacket 16 is preferably made of a resin material whose crushing rate by a predetermined test method is 25% or less.

  FIG. 1B is a diagram for explaining a test method for impact resistance of the optical cable 10, and this test shown in FIG. 1A was performed on the optical cable 10. The optical cable 10 includes an optical fiber core wire 11, a tension member 17, and a cable jacket 16 that covers these members. The optical fiber core 11 includes a multi-mode glass fiber 12 composed of a core and a clad, a coating layer 13 provided on the outer periphery of the glass fiber 12, and a colored layer 14 provided on the surface of the coating layer 13. Has been. Furthermore, the coating layer 13 has a two-layer structure composed of a primary coating 13a (soft layer) in close contact with the glass fiber 12 and a secondary coating 13b (hard layer) provided on the outer periphery of the primary coating 13a. The cable jacket 16 covers the optical fiber core wire 11 and the tension member 17 and is made of a thermoplastic resin with a rectangular cross section of 2 mm × 3 mm along the longitudinal direction of the optical fiber core wire 11. The optical cable 10 is horizontally placed on its long side (surface with a width of 3 mm), and a 2 mm square metal rod 20 is placed on the lower surface of the optical cable 10. In this state, a weight 19 having a diameter of 30 mm and a mass of 1 kg is dropped onto the optical cable 10 from a height position 50 mm above the optical cable 10. The cable jacket 16 of the optical cable 10 according to the first embodiment is formed of a thermoplastic resin such that the crush rate of the cable jacket 16 caused by the falling of the weight 19 is 25% or less.

  According to the optical cable having the above-described structure, even when an impact caused by an external force is applied to the installed optical cable, the deformation due to the crushing of the cable jacket is minimized, and the impact is suppressed. It can reduce that the received part becomes easy to bend. Further, damage to the coating layer and the colored layer in the optical fiber core wire, for example, peeling of the interface between the glass fiber 12 and the coating layer 13, cracking of the coating layer 13 and the colored layer 14 can be reduced.

(Example 1-1)
FIG. 2 is a diagram illustrating a cross-sectional structure of the optical fiber core wire 11a applied to the first example (Example 1-1) of the optical cable 10 according to the first embodiment. The cross section shown in FIG. 2 corresponds to the cross section of the optical fiber core wire 11 applied to the optical cable 10 shown in FIG.

  In the optical cable of Example 1-1, two optical fiber cores 11a (FIG. 2) are arranged in a row as shown in FIG. 1A, and tension is applied to both sides of these optical fiber cores 11a. The member 17 is disposed, and the optical fiber core wire 11a and the tension member 17 are integrally covered with a cable jacket 16 having a rectangular cross section of 2 mm × 3 mm. The cable jacket 16 has a coating thickness of 0.9 mm in a direction orthogonal to the arrangement of the optical fiber cores 11a. The cable jacket 16 is made of a polyamide-based nylon resin that does not contain a halogen having a Young's modulus of 1200 MPa and an elongation at break of 100% and UL flame retardancy of V2. A fiber material in which high-strength polymer fibers are integrated with a polyester resin is applied to the tension member 17.

  A multimode fiber having a core diameter of 50 μm and a cladding diameter of 125 μm is applied to the glass fiber 12 of the optical fiber core 11a. In the optical cable of Example 1-1, from the viewpoint of optimizing the Young's modulus of the coating layer 13, the coating layer 13 is formed on the outer periphery of the glass fiber 12 to an outer diameter of 170 μm. The covering layer 13 has a single-layer structure consisting of only a hard layer, and is specifically made of an ultraviolet curable acrylate resin having a Young's modulus of 800 MPa and a breaking elongation of 56%. Furthermore, the colored layer 14 is formed on the surface of the coating layer 13 to an outer diameter of 180 μm. The colored layer 14 is made of an ultraviolet curable acrylate resin having a Young's modulus of 1200 MPa and a breaking elongation of 2%.

  As a result of the impact resistance test performed on the optical cable of Example 1-1 configured as described above by the method shown in FIG. 1B, the crush rate of the cable jacket 16 in Example 1-1 was determined. Was 15%. Further, the coating layer 13 and the colored layer 14 of the optical fiber core wire 11a are not damaged, and as a result of the temperature test of (−40 ° C. to 125 ° C.) × 3 cycles, the transmission loss increase amount Δα of Example 1-1 is 0.30 dB / 20 m.

  In the optical cable of Example 1-1, a thermoplastic resin having a Young's modulus of 1200 MPa was applied to the cable jacket 16, but as shown in FIG. By using the test method, the crushing rate of the cable jacket could be suppressed to 25% or less. In addition, in the flame retardant test of the optical cable (ISO 6722 45 ° inclination test), the optical cable of Example 1-1 was extinguished in 30 seconds against the standard of extinguishing in 70 seconds or less.

  Regarding the coating damage of the optical fiber core wire 11a, if the Young's modulus of the coating layer 13 of the ultraviolet curable resin on the glass fiber 12 is 200 MPa or more, significant damage can be prevented. However, when the Young's modulus of the cable jacket is too high, the bending rigidity increases, and the flexibility of the cable deteriorates. Moreover, it is preferable that the Young's modulus is 1500 MPa or less from the viewpoint of preventing the elongation at break and becoming easy to break when the Young's modulus increases. Furthermore, since the elongation at break becomes low when the Young's modulus of the cable jacket 16 is high, the Young's modulus is preferably 1200 MPa or less from the viewpoint of long-term reliability.

(Example 1-2)
FIG. 3 is a diagram illustrating a cross-sectional structure of the optical fiber core wire 11b applied to the second example (Example 1-2) of the optical cable 10 according to the first embodiment. The cross section shown in FIG. 3 corresponds to the cross section of the optical fiber core wire 11 used in the optical cable 10 shown in FIG.

  In the optical cable of Example 1-2, two optical fiber cores 11b (FIG. 3) are arranged in a row as shown in FIG. The tension members 17 are disposed on both sides of the optical fiber core 11b, and the optical fiber core 11b and the tension member 17 are integrally covered with a cable jacket 16 having a rectangular cross section of 2 mm × 3 mm. The cable jacket 16 has a thickness of 0.8 mm in a direction orthogonal to the arrangement of the optical fiber core wires 11b. The cable jacket 16 is made of a polyamide-based nylon resin that does not contain a halogen having a Young's modulus of 1200 MPa and an elongation at break of 100% and UL flame retardancy of V2. A fiber material in which high-strength polymer fibers are integrated with a polyester resin is applied to the tension member 17.

  A multimode fiber having a core diameter of 50 μm and a cladding diameter of 125 μm is applied to the glass fiber 12 of the optical fiber core wire 11b. In the optical cable of Example 1-2, a coating layer 13 having an outer diameter of 200 μm is formed on the outer periphery of the glass fiber 12. The covering layer 13 has a single layer structure and is made of an ultraviolet curable acrylate resin having a Young's modulus of 1 MPa and a breaking elongation of 100%.

  Also in the optical cable of Example 1-2, the colored layer 14 is formed on the surface of the covering layer 13. From the viewpoint of increasing the elongation at break of the colored layer 14, the colored layer 14 is made of an ultraviolet curable acrylate resin to which a colorant is added so that the Young's modulus is 1200 MPa and the elongation at break is 10% or more. The outer diameter of the colored layer 14 is 255 μm. Moreover, in the optical cable of Example 1-2, although the density of the coloring agent is reduced in order to increase the elongation at break, the color is increased by making the thickness of the colored layer 27.5 μm thicker than the optical cable of Example 1-1. To compensate for the thinness of the.

  As a result of the impact resistance test performed on the optical cable of Example 1-2 configured as described above by the method shown in FIG. 1B, the crushing rate of the cable jacket 16 in Example 1-2 was determined. Was 16%. Further, the coating layer 13 and the colored layer 14 of the optical fiber core wire 11b are not damaged, and as a result of the temperature test of (−40 ° C. to 125 ° C.) × 3 cycles, the increase amount Δα of the transmission loss in Example 1-2 is , Less than 0.02 dB / 20 m. In the flame retardant test as an optical cable (45 ° inclination test of ISO6722), the optical cable of Example 1-2 was extinguished in 28 seconds against the standard of extinguishing in 70 seconds or less.

  In the optical cable of Example 1-2, a thermoplastic resin having a Young's modulus of 1200 MPa was applied to the cable jacket 16, but as in Example 1-1, a resin having a Young's modulus of 200 MPa or more was applied. Thus, the crushing rate could be suppressed to 25% or less by the test method shown in FIG. Further, regarding the coating damage of the optical fiber core wire 11b, the Young's modulus of the coating layer 13 of the ultraviolet curable resin provided on the outer periphery of the glass fiber 12 is 0.5 MPa to 2 MPa, and the colored layer provided on the surface of the coating layer 13 If the Young's modulus of 14 is in the range of 500 MPa to 1500 MPa, significant damage can be prevented.

(Example 1-3)
FIG. 4 is a diagram illustrating a cross-sectional structure of the optical fiber core wire 11c applied to the third example (Example 1-3) of the optical cable 10 according to the first embodiment. The cross section shown in FIG. 4 corresponds to the cross section of the optical fiber core wire 11 applied to the optical cable 10 shown in FIG.

  In the optical cable of Example 1-3, two optical fiber cores 11c (FIG. 4) are arranged in a row as shown in FIG. The tension member 17 is disposed on both sides of the optical fiber core 11c, and the optical fiber core 11c and the tension member 17 are integrally covered with a cable jacket 16 having a rectangular cross section of 2 mm × 3 mm. The cable jacket 16 has a thickness of 0.7 mm in a direction orthogonal to the arrangement of the optical fiber cores 11c. The cable jacket 16 is made of a polyamide-based nylon resin that does not contain a halogen having a Young's modulus of 1200 MPa and an elongation at break of 100% and UL flame retardancy of V2. A fiber material in which high-strength polymer fibers are integrated with a polyester resin is applied to the tension member 17.

  A multimode fiber having a core diameter of 50 μm and a cladding diameter of 125 μm is applied to the glass fiber 12 of the optical fiber core 11c. In the optical cable of Example 1-3, a coating layer 13 is formed on the outer periphery of the glass fiber 12. The coating layer 13 has a two-layer structure composed of a primary coating 13a (soft layer) and a secondary coating 13b (hard layer). The primary coating 13a is formed from the surface of the glass fiber 12 to an outer diameter of 200 μm, and is made of an ultraviolet curable acrylate resin having a Young's modulus of 1 MPa and a breaking elongation of 100%. The secondary coating 13b is formed of an ultraviolet curable acrylate resin having an outer diameter of 245 μm on the surface of the primary coating 13a, a Young's modulus of 800 MPa, and a breaking elongation of 56%. Further, a colored layer 14 having an outer diameter of 255 μm is formed on the surface of the secondary coating 13b, and this colored layer 14 is made of an ultraviolet curable acrylate resin having a Young's modulus of 1200 MPa and a breaking elongation of 2%.

  In the optical cable of Example 1-3, the protective layer 15 having a thickness of 125 μm is formed on the surface of the colored layer 14 from the viewpoint of protecting the periphery of the optical fiber core wire 11c with a resin having a low Young's modulus. The protective layer 15 is made of an ultraviolet curable acrylate resin having a Young's modulus of 50 MPa and an elongation at break of 80%. In the optical cable of Example 1-3, the protective layer 15 is provided for each of the optical fiber cores 11c. However, a plurality of optical fiber cores each coated up to the colored layer 14 are protected layers. 15 may be integrally covered. In this case, the protective layer 15 has a tape shape in which a plurality of optical fiber cores are arranged in a line.

  As a result of the impact resistance test performed on the optical cable of Example 1-3 configured as described above by the method illustrated in FIG. 1B, the crush rate of the cable jacket 16 in Example 1-3 was determined. Was 17%. Further, the coating layer 13 (the primary coating 13a and the secondary coating 13b) and the colored layer 14 of the optical fiber core wire 11c were not damaged, and the results of the temperature test of (−40 ° C. to 125 ° C.) × 3 cycles showed that Example 1 The increase amount Δα of −3 transmission loss was less than 0.02 dB / 20 m. Moreover, in the flame retardance test (452 inclination test of ISO6722) as a cable, the optical cable of Example 1-3 was extinguished in 29 seconds, against the standard of extinguishing in 70 seconds or less.

  In the optical cable of Example 1-3, a thermoplastic resin having a Young's modulus of 1200 MPa was applied to the cable jacket 16, but as in Example 1-1, a resin having a Young's modulus of 200 MPa or more was applied. The crushing rate could be suppressed to 25% or less by the test method shown in FIG.

  Regarding the coating damage of the optical fiber core 11c, if the Young's modulus of the UV curable resin of the protective layer 15 is less than 50 MPa, the protective layer is easily peeled off in the bobbin winding state of the optical fiber core before being cabled. On the other hand, when the Young's modulus is 300 MPa or more, the impact absorbing effect against dropping of the weight is lowered. The primary coating 13a of the ultraviolet curable resin provided on the surface of the glass fiber 12 preferably has a Young's modulus of 0.5 MPa to 2 MPa, and the colored layer 14 has a pressure of 200 MPa from the viewpoint of preventing significant damage due to side pressure or the like. It is preferable to have the above Young's modulus. However, significant damage can be prevented if the Young's modulus of the colored layer 14 is 1500 MPa or less from the viewpoint of preventing the elongation at break and becoming easy to crack as the Young's modulus increases.

(Example 1-4)
FIG. 5 is a diagram illustrating a cross-sectional structure of an optical fiber core wire 11d applied to the fourth example (Example 1-4) of the optical cable 10 according to the first embodiment. The cross section shown in FIG. 5 corresponds to the cross section of the optical fiber core wire 11 applied to the optical cable 10 shown in FIG. In addition, the structure of the optical fiber core wire 11d in the optical cable of Example 1-4 is the same as that of Example 1-1 except for the colored layer 14.

  In the optical cable of Example 1-4, two optical fiber cores 11d (FIG. 5) are arranged in a row as shown in FIG. 1A, and tension is applied to both sides of these optical fiber cores 11d. The member 17 is disposed, and the optical fiber core wire 11d and the tension member 17 are integrally covered with a cable jacket 16 having a rectangular cross section of 2 mm × 3 mm. The cable jacket 16 has a coating thickness of 0.9 mm in a direction orthogonal to the arrangement of the optical fiber cores 11d. The cable jacket 16 is made of a polyamide-based nylon resin that does not contain a halogen having a Young's modulus of 1200 MPa and an elongation at break of 100% and UL flame retardancy of V2. A fiber material in which high-strength polymer fibers are integrated with a polyester resin is applied to the tension member 17.

  A multimode fiber having a core diameter of 50 μm and a cladding diameter of 125 μm is applied to the glass fiber 12 of the optical fiber core 11d. In the optical cable of Example 1-4, from the viewpoint of optimizing the Young's modulus of the coating layer 13, the coating layer 13 is formed on the outer periphery of the glass fiber 12 to an outer diameter of 170 μm. The covering layer 13 has a single-layer structure consisting of only a hard layer, and is specifically made of an ultraviolet curable acrylate resin having a Young's modulus of 800 MPa and a breaking elongation of 56%.

  As a result of the impact resistance test performed on the optical cable of Example 1-4 configured as described above by the method shown in FIG. 1B, the crushing rate of the cable jacket 16 in Example 1-4 was determined. Was 16%. Further, the coating layer 13 of the optical fiber core wire 11d was not damaged, and as a result of the temperature test of (−40 ° C. to 125 ° C.) × 3 cycles, the increase Δα in transmission loss in Example 1-1 was 0.28 dB. / 20 m.

  In the optical cable of Example 1-4, a thermoplastic resin having a Young's modulus of 1200 MPa was applied to the cable jacket 16, but as shown in FIG. By using the test method, the crushing rate of the cable jacket could be suppressed to 25% or less. Moreover, in the flame retardance test (45 ° inclination test of ISO6722) of the optical cable, the optical cable of Example 1-4 was extinguished in 30 seconds, compared to the standard of extinguishing in 70 seconds or less.

  Regarding the coating damage of the optical fiber core wire 11d, if the Young's modulus of the coating layer 13 of the ultraviolet curable resin on the glass fiber 12 is 200 MPa or more, significant damage can be prevented. However, when the Young's modulus of the cable jacket is too high, the bending rigidity increases, and the flexibility of the cable deteriorates. Moreover, it is preferable that the Young's modulus is 1500 MPa or less from the viewpoint of preventing the elongation at break and becoming easy to break when the Young's modulus increases. Furthermore, since the elongation at break is low when the Young's modulus of the cable jacket 16 is high, the Young's modulus is preferably 1200 MPa or less from the viewpoint of long-term reliability.

(Example 1-5)
FIG. 6 is a diagram illustrating a cross-sectional structure of an optical fiber core wire 11e applied to a fifth example (Example 1-5) of the optical cable 10 according to the first embodiment. The cross section shown in FIG. 6 corresponds to the cross section of the optical fiber core wire 11 applied to the optical cable 10 shown in FIG. The optical fiber core wire 11e in the optical cable of Example 1-5 is substantially the same as Example 1-3 except for the colored layer 14 and the protective layer 15.

  In the optical cable of Example 1-5, two optical fiber cores 11e (FIG. 6) are arranged in a row as shown in FIG. The tension member 17 is disposed on both sides of the optical fiber core 11e, and the optical fiber core 11e and the tension member 17 are integrally covered with a cable jacket 16 having a rectangular cross section of 2 mm × 3 mm. The cable jacket 16 has a thickness of 0.7 mm in a direction orthogonal to the arrangement of the optical fiber core wires 11e. The cable jacket 16 is made of a polyamide-based nylon resin that does not contain a halogen having a Young's modulus of 1200 MPa and an elongation at break of 100% and UL flame retardancy of V2. A fiber material in which high-strength polymer fibers are integrated with a polyester resin is applied to the tension member 17.

  A multimode fiber having a core diameter of 50 μm and a cladding diameter of 125 μm is applied to the glass fiber 12 of the optical fiber core 11e. In the optical cable of Example 1-5, the coating layer 13 is formed on the outer periphery of the glass fiber 12. The coating layer 13 has a two-layer structure composed of a primary coating 13a (soft layer) and a secondary coating 13b (hard layer). The primary coating 13a is formed from the surface of the glass fiber 12 to an outer diameter of 200 μm, and is made of an ultraviolet curable acrylate resin having a Young's modulus of 1 MPa and a breaking elongation of 100%. The secondary coating 13b is formed of an ultraviolet curable acrylate resin having an outer diameter of 245 μm on the surface of the primary coating 13a, a Young's modulus of 800 MPa, and a breaking elongation of 56%. Note that the optical fiber core wire 11e in the optical cable of Example 1-5 does not have the colored layer 14 and the protective layer 15 as in Example 1-3.

  As a result of the impact resistance test performed on the optical cable of Example 1-5 configured as described above by the method shown in FIG. 1B, the crush rate of the cable jacket 16 in Example 1-5 was determined. Was 18%. In addition, the coating layer 13 (the primary coating 13a and the secondary coating 13b) of the optical fiber core wire 11e is not damaged, and as a result of the temperature test of (−40 ° C. to 125 ° C.) × 3 cycles, the transmission of Example 1-5 The increase in loss Δα was less than 0.02 dB / 20 m. In addition, in the flame retardant test as a cable (45 ° inclination test of ISO6722), the optical cable of Example 1-5 was extinguished in 29 seconds as opposed to the standard of extinguishing in 70 seconds or less.

  In the optical cable of Example 1-5, a thermoplastic resin having a Young's modulus of 1200 MPa was applied to the cable jacket 16, but as in Example 1-1, a resin having a Young's modulus of 200 MPa or more was applied. The crushing rate could be suppressed to 25% or less by the test method shown in FIG.

(Comparative Example 1-1)
Hereinafter, a first comparative example (Comparative Example 1-1) of the optical cable 10 according to the first embodiment will be described. The structure of the optical cable of Comparative Example 1-1 is the same as the cable structure shown in FIG. 1A (the same cable structure as in Examples 1-1 to 1-5). However, in the optical cable of Comparative Example 1-1, the thermoplastic resin of the cable jacket 16 is made of a halogen having a flame retardancy of V0, which is higher in flame retardancy than V2 in the UL standard with a Young's modulus of 100 MPa and an elongation at break of 200%. Polyolefin resin not containing is applied. The optical fiber core has a two-layer coating layer, similar to the optical fiber core of FIG. 4 (the optical fiber core 11c applied to the optical cable of Example 1-3). In this coating layer, a primary coating (soft layer) is formed on the surface of the glass fiber up to an outer diameter of 200 μm, and this primary coating is made of an ultraviolet curable acrylate resin having a Young's modulus of 1 MPa and a breaking elongation of 100%. A secondary coating (hard layer) is formed on the surface of the primary coating to an outer diameter of 245 μm, and this secondary coating is an ultraviolet curable acrylate resin having a Young's modulus of 800 MPa and a breaking elongation of 56%. Further, a colored layer having an outer diameter of 255 μm is formed on the surface of the secondary coating, and this colored layer is made of an ultraviolet curable acrylate resin having a Young's modulus of 1200 MPa and an elongation at break of 2%. Unlike Example 1-3, the optical fiber core wire in the optical cable of Comparative Example 1-1 does not have a protective layer.

  With respect to the optical cable of Comparative Example 1-1 configured as described above, the impact resistance test was performed by the method shown in FIG. 1B. As a result, the crushing rate of the cable jacket was 50%. Further, peeling of the UV curable resin coating was observed at the interface of the optical fiber core wire with the glass, and the colored layer was also damaged. As a result of performing a temperature test of (−40 ° C. to 125 ° C.) × 3 cycles, the increase Δα in transmission loss in Comparative Example 1-1 was 0.02 dB / 20 m. Moreover, in the flame retardance test (45 degree inclination test of ISO6722) as a cable, the optical cable of the comparative example 1-1 was extinguished in 25 seconds with respect to the standard of extinguishing in 70 seconds or less.

(Comparative Example 1-2)
On the other hand, the second comparative example (Comparative Example 1-2) optical cable of the optical cable 10 according to the first embodiment also has the cable structure shown in FIG. However, unlike the comparative example 1-1, the thermoplastic resin of the cable jacket 16 is a polyamide-based nylon resin that does not contain a halogen that has a Young's modulus of 1200 MPa and a fracture elongation of 100% and has a UL flame resistance of V2. Has been applied. The coating layer of the optical fiber core has a double structure composed of a primary coating and a secondary coating, similar to Example 1-3 shown in FIG. That is, a primary coating is formed on the surface of the glass fiber to an outer diameter of 200 μm, and this primary coating is made of an ultraviolet curable acrylate resin having a Young's modulus of 1 MPa and a breaking elongation of 100%. A secondary coating having an outer diameter of 245 μm is formed on the surface of the primary coating, and the secondary coating is made of an ultraviolet curable acrylate resin having a Young's modulus of 800 MPa and a breaking elongation of 56%. Further, a colored layer having an outer diameter of 255 μm is formed on the surface of the secondary coating, and this colored layer is made of an ultraviolet curable acrylate resin having a Young's modulus of 1200 MPa and an elongation at break of 2%. Also in Comparative Example 1-2, the optical fiber core wire has no protective layer (same as Comparative Example 1-1).

  The optical cable of Comparative Example 1-2 configured as described above was subjected to an impact resistance test by the method shown in FIG. 1B. As a result, the crushing rate of the cable jacket was 15%. However, the UV curable resin coating was peeled off at the interface of the optical fiber core with the glass, and the colored layer was also damaged. As a result of the temperature test of (−40 ° C. to 125 ° C.) × 3 cycles, the increase Δα in transmission loss in Comparative Example 1-2 was 0.02 dB / 20 m. In addition, in the flame retardancy test (45 ° inclination test of ISO6722) as a cable, the optical cable of Comparative Example 1-2 was extinguished in 35 seconds as opposed to the standard of extinguishing in 70 seconds or less.

  Next, FIG. 7 shows impact characteristics and temperature as endurance performance of each of Examples 1-1 to 1-5, Comparative Example 1-1, and Comparative Example 1-2 of the optical cable 10 according to the first embodiment. It is a table | surface which shows the determination result of a characteristic. FIG. 7 shows the result of comprehensively judging whether the cable jacket is crushed, whether the optical fiber core is damaged (checked with tentacles or visually), and the increase in transmission loss due to the thermal cycle test. Has been. Further, the structure of the optical cable is the same in all examples, and in Examples 1-1 to 1-5, a nylon resin having a Young's modulus of 1200 MPa and a breaking elongation of 100% is applied to the cable jacket, and the optical fiber core wire The structures and materials of the coating layers are different from each other. On the other hand, in Comparative Examples 1-1 and 1-2, the structure of the optical fiber core wire is the same (having a double-layer coating layer as in Example 1-3), but the material of the cable jacket is They are different from each other.

  As shown in FIG. 1B, the crushing rate of the cable jacket is determined by the result of dropping a weight having a diameter of 30 mm and a mass of 1 kg onto the optical cable from 50 mm above the optical cable to be measured. . In addition, this criterion was “good” for a crushing rate of 25%, and “bad” for a crushing rate of 25% or more. The determination of the presence or absence of damage to the optical fiber core wire was made by checking the peeling or crushing of the coating with the tentacles or the visual observation. Furthermore, the increase in transmission loss was measured by performing a temperature test of (−40 ° C. to 125 ° C.) × 3 cycles, and 0.5 dB / 20 m or less was determined as “good”.

  As can be seen from the determination results shown in FIG. 7, in each example, the temperature test of (−40 ° C. to 125 ° C.) × 3 cycles yielded no problem in practical use. In the optical cable of Example 1-1, the transmission loss is increased to 0.3 dB / 20 m as compared with the other examples, but optical LAN communication and inter-device wiring used within a range of about 20 m. Is an acceptable range. Regarding the impact test, Examples 1-1 to 1-5 and Comparative Example 1-2 clear the crush rate of the outer cover of 25% or less. In Examples 1-1 to 1-5, no core damage was observed in any of the coating layer and the colored layer of the optical fiber core wire, and the overall judgment was “good” even when combined with the temperature characteristics. In Comparative Example 1-1 and Comparative Example 1-2, damage was observed in the colored layer of the optical fiber core wire, and the overall judgment was “bad”.

(Second Embodiment)
Next, a second embodiment of the optical cable according to the present invention will be described in detail with reference to FIGS. FIG. 8 is a diagram showing a basic structure (cross-sectional structure) and an appearance of a second embodiment of the optical cable according to the present invention. In particular, FIG. 8A shows a first cross-sectional structure (rectangular shape) of the optical cable 20 according to the second embodiment, and FIG. 8B shows a second cross-sectional structure of the optical cable 20 according to the second embodiment ( FIG. 8C shows an example of a LAN optical cable to which the optical cable 20 is applied (a state in which an optical connector is attached). Similarly to the first embodiment, the optical cable 20 according to the second embodiment includes an optical fiber core 11 and tension members 17 disposed on both sides of the optical fiber core 11 along the optical fiber core 11. A cable jacket 16 that integrally covers the optical fiber core wire 11 and the tension member 17 is provided. The optical fiber core 11 includes a bare fiber (glass fiber) 12, a coating layer 13 provided on the outer periphery of the glass fiber 12, and a colored layer 14 provided on the surface of the coating layer 13. The glass fiber 12 includes a core having a predetermined refractive index extending along a predetermined axis on the surface, and a clad having a lower refractive index than the core provided on the outer periphery of the core. The coating layer 13 may have a multilayer structure composed of a primary coating (soft layer) 13a and a secondary coating (hard layer) 13b, or may have a single layer structure.

  The optical cable 20 according to the second embodiment is an optical cable for optically connecting a plurality of information devices installed indoors or in a vehicle, and has a relatively short distance (for example, about 1 m to 20 m). It is an optical cable (LAN optical cable) suitable for use in LAN, inter-device wiring, etc. with optical wiring. In this type of optical cable, for example, as shown in FIG. 8A, optical fiber cores 11 are arranged in a line, tension members 17 are arranged on both sides of the optical fiber cores 11, and the optical fiber cores are arranged. It is obtained by integrally covering the wire 11 and the tension member 17 with the cable jacket 16. In the second embodiment, the tension member 17 located in the cable jacket 16 may be excluded.

  As the glass fiber 12 of the optical fiber core 11, a multimode glass fiber 12 made of quartz glass, having a core diameter of 50 μm and a cladding diameter of 125 μm is applicable. In addition, the optical fiber mainly made of quartz glass may be one in which both the core and the clad are made of quartz glass, or only the core is made of quartz glass and the clad is made of hard plastic. There may be.

  The optical fiber core 11 is provided on the surface of the coating layer 13b when the glass fiber 12 and the coating layers 13a and 13b coated on the surface of the glass fiber 12 (having an outer diameter of about 245 μm made of an ultraviolet curable acrylate resin) It is provided with a colored layer 14. The coating layer preferably has a two-layer structure of a primary coating 13a (soft layer) and a secondary coating 13b (hard layer), in which case the Young's modulus of the inner primary coating 13a is set to the outer two layers. By making it smaller than the Young's modulus of the secondary coating 13b, it is possible to give a side buffering function to the optical fiber core 11. Therefore, the optical fiber core 11 having such a multi-layered coating layer 13 is a microbend. Generation can be effectively suppressed and good optical transmission characteristics can be maintained.

  In the optical cable 20 according to the second embodiment, two or more optical fiber cores 11 are disposed side by side, tension members 17 are disposed at both ends thereof, and the optical fiber core wire 11 and the tension member 17 are further disposed. Are integrally covered with the cable jacket 16 (integration of the optical fiber core and the cable jacket), the optical fiber core 10 is obtained. In the second embodiment, the tension member 17 is not provided and it is very good. Here, “integration of the optical fiber core and the cable jacket” means that the optical fiber core 11 embedded in the cable jacket 16 is in direct contact with the cable jacket 16 and is jointly subjected to tensile stress. It means a state that can be handled. As will be described later, the tension member 17 may not be particularly required in a use form in which a large tension is not always applied as in the case of LAN wiring, as long as the tensile tension of the entire optical cable can be secured to a predetermined value or more.

  The cable jacket 16 is made of a thermoplastic resin such as nylon resin, polyethylene (PE), polyvinyl chloride (PVC), and has a rectangular shape, for example, as shown in FIGS. 8 (a) and 8 (b). Or it has an elliptical cross section. The cable jacket 16 is formed by full extrusion. Solid extrusion is a method of performing extrusion while applying pressure to the optical fiber core 11 or the like so as to compress the extruded resin inside the die of the resin extruder. The extruded resin is in a compressed state in the die, and the thermoplastic resin extruded on the outer periphery of the optical fiber core wire 11 can have high adhesion to the optical fiber core wire 11 as the cable jacket 16. it can. The cable jacket 16 is in close contact with the optical fiber core 11 to prevent the optical fiber core 11 from meandering in the cable and increasing loss when the cable jacket 16 contracts. can do.

  Further, the elongation at break of the optical fiber core 11 is generally 5% or more, but if the stretched state continues even below the elongation at break, static fatigue occurs due to the growth of cracks existing in the glass, and the wire breaks with a certain probability over time. To do. Considering the fracture life of the fiber glass part, it is also important to optimize the screening level at the time of drawing the optical fiber core wire. When the screening level is 1.5%, even if 1% of elongation corresponding to 2/3 of the screening level is added to the optical fiber core when the optical cable is wired, the probability of glass breakage after 10 years is 1 million. It can be suppressed to a very low value of 1 or less.

  In the optical cable according to the present invention, since the optical fiber core wire and the cable jacket are integrated, the optical fiber extension and the cable extension are substantially equal. For this reason, by suppressing the cable jacket elongation to 1% or less, the optical fiber elongation can also be suppressed to approximately 1% or less, and the breaking probability of glass can be suppressed to a very low level. Therefore, the total tensile tension of the optical fiber cable when the optical cable is extended by 1% along the longitudinal direction means the tensile tension when the optical cable is extended by 1% by gripping the cable jacket. The tensile tension of a member such as an optical fiber core wire integrated with the cover is also taken into consideration.

  When the optical cable 20 is applied to LAN wiring or indoor wiring in an indoor environment, it is sufficient to assume that a tensile tension of about 50 N is applied. Therefore, as a practical optical cable, a total of 50 N including the optical fiber core wire 11, the tension member 17, and the cable jacket 16 constituting the cable 20 (preferably 70 N which is a general allowable tension). It is only necessary to have a tensile strength that can withstand the tension of). Further, as the LAN wiring and the inter-device wiring, there is a demand for a thin optical cable as well as a reduction in wiring space and an improvement in handleability. In this second embodiment, the outer dimension of the cable jacket 16 is 4 mm or less. The cross section is rectangular or elliptical (preferably a rectangular cross section of 2 mm × 3 mm) and has directivity in the bending direction, and does not include a metal wire that easily causes metal fatigue as a strength member.

  Further, as shown in FIG. 8 (c), the optical cable 20 according to the second embodiment is attached to the end portion of the optical cable 20 according to the second embodiment with a connecting portion for optical components such as the optical connector 9, the light source module, and the light receiving module. In many cases, it is necessary that the optical component is easily mounted. For example, with respect to the mountability of the optical connector 9, since the optical fiber core wire 11 and the cable jacket 16 are integrated, the optical connector 9 can be fixed simply by gripping the cable jacket 16, The workability is simple and good. Even if the cable jacket 16 is held and fixed by the optical connector 9, if the Young's modulus of the cable jacket 16 is low, only the cable jacket may be stretched when the optical connector 9 is pulled. Therefore, when the Young's modulus of the cable jacket 16 is 200 MPa or more, preferably 300 MPa or more, and the optical cable including the optical fiber core wire 11 and the cable jacket 16 is extended by 1% in the longitudinal direction, It is preferable that the tensile tension is 50 N or more, which is the tension regulation for general optical connectors.

  Further, in the optical cable 20 according to the second embodiment, since the cable jacket 16 and the optical fiber core 11 are integrated, at a low temperature, the optical fiber core 11 is likely to cause microbending and increase transmission loss. . For this, a rod-shaped wire (FRP rod) in which high-strength fibers repelling the shrinkage of the cable jacket are hardened with resin is used not only as a tension member (strength member) but also as an anti-shrink member. . In addition, it is good also as a form which does not use preferentially the flexibility of a cable.

  When an anti-shrinking member is not used, a soft layer (low Young's modulus) is formed on the surface of the glass fiber 12 of the optical fiber core 11 so that the optical fiber core 11 is not easily affected by the microbend. A primary coating 13a) is preferably provided. Specifically, a coating of 10 MPa or less, which is about two orders of magnitude lower than the Young's modulus of 800 MPa to 1200 MPa, used for the outermost layer (secondary coating or colored layer 14) of the optical fiber core wire 11 from the viewpoint of trauma resistance. By providing it between the surface and the outermost layer, the micro bend diameter of the microbend can be increased. In this case, transmission loss can be kept good even at low temperatures. If the primary coating 13a is too soft, the position of the quartz glass is not stabilized and the eccentricity is deteriorated. Therefore, the Young's modulus of the primary coating 13a is preferably 0.1 MPa or more.

  According to the optical cable having the above-described structure, the optical cable can sufficiently withstand the tension applied temporarily at the time of laying, and such an optical cable is broken by a bending test of 100,000 times at 90 ° right and left with a radius of curvature of R9 mm. In addition, it has a high bending performance that does not cause a problem, and is excellent in mounting workability of the optical connector.

(Example 2-1)
FIG. 9 is a diagram illustrating a cross-sectional structure of the first example (Example 2-1) of the optical cable 20 according to the second embodiment.

  In the optical cable 20a of Example 2-1, no tension member is present in the cable jacket 16. The optical cable 20a of Example 2-1 is obtained by arranging two optical fiber cores 11 in a row and covering these optical fiber cores 11 integrally with a cable jacket 16 of 2 mm × 3 mm. A multimode glass fiber having a core diameter of 50 μm and a cladding diameter of 125 μm is applied to the glass fiber 12 of the optical fiber core wire 11. The coating layer 13 is formed from the surface of the glass fiber 12 to an outer diameter of 250 μm. The coating layer 13 is made of an ultraviolet curable acrylate resin, and includes a primary coating 13a and a secondary coating 13b. The primary coating 13a is formed from the surface of the glass fiber 12 to an outer diameter of 200 μm, and its Young's modulus is as low as 1 MPa. The Young's modulus of the secondary coating 13b formed from the surface of the primary coating 13a to 250 μm is 800 MPa. The cable jacket 16 is formed by full extrusion molding of a nylon resin having a Young's modulus of 1200 MPa.

  The elongation rigidity of the optical cable 20a of Example 2-1 having the above-described structure will be described. The elongation rigidity is a value represented by the product ES (unit: N) of the Young's modulus E and the cross-sectional area S. In the case of the optical cable 20a of Example 2-1, in an environment of 23 ° C., the glass fiber 12 has a diameter of 125 μm and a Young's modulus of 68.6 GPa. Therefore, the elongation rigidity of the two glass fiber portions is 1.7 kN. is there. Since the outer diameter of the cable jacket 16 is 2 mm × 3 mm and the Young's modulus is 1200 MPa, the elongation rigidity of the cable jacket 16 is 7.2 kN. When the screening level of the optical fiber core 11 is 1.5%, the optical fiber core 11 can be extended along its longitudinal direction up to 1%. Therefore, the total tensile tension of the optical cable 20a when the optical cable 20a is extended by 1% along the longitudinal direction thereof is 89N, which can exceed the general allowable tension 50N for indoor work that is normally considered. . In this case, if the cable jacket 16 has a Young's modulus of 500 MPa or more, the cable outer sheath 16 can exceed the general allowable tension 50N in indoor work that is normally considered.

  However, when the Young's modulus of the cable jacket 16 is increased, the cable bending rigidity is also increased, the cable is hard to be bent, and the cable handling property is also deteriorated. For this reason, it is preferable to keep the Young's modulus of the cable jacket 16 to about 1500 MPa. In order to increase the tensile strength of the cable jacket 16, it is conceivable to increase the cross-sectional area of the cable jacket 16. However, considering the wiring space of the optical cable, the outer dimension (maximum outer diameter) of the optical cable is preferably 4 mm or less. In consideration of this point, in order to set the total tensile tension of the optical cable 20a (when the optical cable 20a is extended by 1% along the longitudinal direction) to 70 N or more, the Young's modulus of the cable jacket 16 is 200 MPa. It is necessary to be above.

  Regarding the bending performance of the optical cable, the bending strain applied to the glass fiber portion of the optical fiber core wire 11 is maximum when it is bent at a bending radius R9 mm that is slightly less than 5 times the short dimension (2 mm width) of the cable cross section (2 mm × 3 mm). However, it falls to 0.7% and 1% or less. Since the lifetime of glass is mainly determined by the accumulated time of strain, the influence of the number of bendings is small, and unlike steel wires that cause metal fatigue, glass is a material that is less susceptible to dynamic fatigue. Therefore, even when about 100,000 reciprocations are added at a bending radius of R9 mm (see the bending test example in FIG. 5), the fracture probability of glass is as low as 1 / million or less, and no practical disconnection occurs.

  The breaking elongation of the nylon resin used for the cable jacket 16 is 100%, which is an order of magnitude different from the bending strain applied to the cable jacket 16 at the time of bending. Therefore, damage such as cracks did not occur in the cable jacket 16. Furthermore, in order to prevent the cable jacket 16 from cracking even if it is bent 100,000 times reciprocally at a bending radius R9 mm that is slightly less than 5 times the short side of the cable cross section, the breaking elongation of the cable jacket 16 is increased. It has also been found that it should be at least 10 times the maximum strain applied to the cable jacket 16, that is, 100% or more.

  In addition, in the optical cable 20a of Example 2-1, nylon resin was used for the cable jacket 16, but polyurethane resin and polyethylene resin have a high Young's modulus like nylon resin, and a wide variety of resins can be selected. It is. Further, by selecting a resin having a melting point of about 150 ° C., for example, wiring in a high temperature environment of about 125 ° C. such as around an automobile engine becomes possible.

  As a result of the temperature test of (−40 ° C. to 125 ° C.) × 3 cycles, the increase Δα in transmission loss in Example 2-1 was as good as 0.02 dB / 20 m. In addition, if a soft coating resin having a Young's modulus of 10 MPa or less is applied to the surface of the glass fiber 12 as a primary coating 13a (soft layer) formed from the surface of the glass fiber 12 to an outer diameter of 150 μm or more, Example 2- The transmission loss increase amount Δα of 1 is suppressed to 0.1 dB / km or less. However, if the Young's modulus of the primary coating 13a is too low, the glass fiber 12 cannot be firmly fixed and the eccentricity becomes high. Therefore, the Young's modulus of the primary coating 13a is preferably 0.1 MPa or more. With respect to the mountability of the optical connector, in the case of the optical cable 20a of Example 2-1, since the optical fiber core wire 11 and the thermoplastic resin of the cable jacket 16 are integrated in close contact, the cable jacket 16 Can be fixed simply by gripping with the gripping portion of the optical connector, and can be easily mounted.

(Example 2-2)
FIG. 10 is a diagram illustrating a cross-sectional structure of a second example (Example 2-2) of the optical cable 20 according to the second embodiment.

  In the optical cable 20b of Example 2-2, a tension member 17a made of high-strength fiber is embedded in the cable jacket 16. In the optical cable 20b of Example 2-2, two optical fiber cores 11 are arranged in a row in the same manner as in Example 2-1 of FIG. 9, and high tension members 17a are provided on both sides of these optical fiber cores 11. The strength fiber bundle is arranged, and the optical fiber core wire 11 and the tension member 17a are integrally covered with a cable jacket 16 of 2 mm × 3 mm. A multimode glass fiber having a core diameter of 50 μm and a cladding diameter of 125 μm is applied to the glass fiber 12 of the optical fiber core wire 11. A coating layer 13 made of an ultraviolet curable acrylate resin is formed on the outer periphery of the glass fiber 12 from the surface of the glass fiber 12 to an outer diameter of 250 μm. The cable jacket 16 is formed by solid extrusion molding of a soft (Young's modulus 100 MPa) polyolefin resin.

A PBO (poly-p-phenylenebenzobisoxazole) polymer fiber having a Young's modulus of 180 GPa (the diameter when bundled is about 0.4 mm) is applied to the high-strength fiber bundle. When full extrusion is performed, the resin pressure can be set as high as 500 MPa at the die and the point portion of the extruder, so that high-strength fibers can be strongly tightened with the resin of the jacket. Thereby, even if the optical cable 20b is pulled in a state where only the cable jacket is gripped at the terminal portion, the applied tension is surely transmitted to the high-strength fiber bundle. In addition, since micron-order ultrafine high-strength fibers are fastened by the cable jacket 16, when cutting with a general-purpose tool such as a nipper, the high-strength fibers can be easily cut without being separated. Specifically, the density of the high-strength fiber is about 15,000 dtex / mm ² (13,500 denier / mm ² ).

  This density can be rephrased as “a density at which the force (pulling force) when pulling out the high-strength fiber bundle from the cable jacket is 50 N / cm or more”. The high-strength fibers cannot be removed even if the cable jacket 16 is pulled with a tension of 50 N with a length of about 1 cm at which the optical connector grips the jacket, so that the applied tension is reliably transmitted to the high-strength fiber bundle. In addition, the back tension of the high strength fiber at the time of manufacture can be manufactured at a low value of about 2N.

  Regarding the elongation rigidity of the optical cable 20b of Example 2-2, for example, the elongation rigidity (ES product) of the high-strength polymer fiber bundle is 45 kN, the elongation rigidity of the fiber glass portion is 1.7 kN, and the cable jacket 16 The elongation rigidity is 0.6 kN. For this reason, for example, even if the optical fiber core wire has a low screening level of 0.3% and can be extended only to 0.2%, the allowable tension of the optical cable 20b is 94 N, which is normally considered. It is possible to exceed a tensile tension of 50 N for indoor work or a general allowable tension of 70 N.

  As for the bending performance of the optical cable 20b, for example, as in the case of Example 2-1 in FIG. 9, when the optical cable 20b is bent to the short side with a bending radius R9 mm, a high-strength polymer having a diameter of 0.4 mm is used. When the fiber bundle is completely fixed by the cable jacket 16, the maximum strain of 2% is applied. However, since the periphery of the high-strength fiber bundle is actually only restrained by the soft thermoplastic resin of the cable jacket 16, the high-strength fiber is in the longitudinal direction although there is fiber friction when the optical cable 20b is bent. Can move slightly. For this reason, even if the optical cable 20b is bent, the maximum strain generated in the high-strength fiber is more surely relaxed than 2% and is not easily broken. In order to shift the high-strength fibers when the optical cable 20b is bent, the pulling force of the high-strength fiber bundle is preferably 900 N / cm or less corresponding to the tension at the maximum strain of 2%. Here, the pulling force as a high-strength fiber bundle is described, but the force when pulling out one high-strength fiber or a part of the high-strength fiber is not more than a value obtained by multiplying the cross-sectional area ratio with respect to the high-strength fiber bundle. It becomes.

  The tension member 17a in the optical cable 20b of Example 2-2 is a bundle of ultrafine fibers in units of microns, and the fibers are independent. Therefore, even if the fiber where the maximum strain occurs is cut, it is not greatly affected by the cut fiber. Further, in Example 2-2, an example of the PBO fiber is shown as the applied tension member 17a. However, a high-strength polymer fiber such as an aramid fiber, an inorganic fiber carbon fiber, or the like may be applied. In addition, since carbon fiber has electroconductivity, it can be made to function as an object for electric power feeding of a light emitting element or a light receiving element. Therefore, the carbon fiber can achieve both the bending property and the conductivity, which are impossible with a metal wire that undergoes fatigue fracture. As for the mountability of the optical connector 9, since the optical fiber core wire 11 and the high-strength fiber (tension member 17a) constituting the optical cable 20b and the thermoplastic resin of the cable jacket 16 are integrated in close contact with each other, The cable jacket 16 can be fixed simply by gripping it with the gripping portion of the optical connector 9 and can be easily attached.

(Example 2-3)
FIG. 11 is a diagram illustrating a cross-sectional structure of a third example (Example 2-3) of the optical cable 20c according to the second embodiment.

  In the optical cable 20c of Example 2-3, high-strength FRP (Fiber Reinforced Plastics) is embedded as a tension member 17b in the cable jacket 16. In the optical cable 20c of Example 2-3, similarly to Example 2-1 of FIG. 9, two optical fiber cores 11 are arranged in a row, and tension members 17b are provided on both sides of the optical fiber cores 11 as high members. A rod-shaped member having strength FRP is arranged, and the optical fiber core wire 11 and the tension member 17b are integrally covered with a 2 mm × 3 mm cable jacket 16. A multimode glass fiber having a core diameter of 50 μm and a cladding diameter of 125 μm is applied to the glass fiber 12 of the optical fiber core wire 11. A coating layer 13 made of an ultraviolet curable acrylate resin is formed on the outer periphery of the glass fiber 12 from the surface of the glass fiber 12 to an outer diameter of 250 μm. The cable jacket 16 is formed by solid extrusion molding of a soft (Young's modulus 100 MPa) polyolefin resin.

  For high-strength FRP, a rod-shaped wire having an outer diameter of about 0.4 mm obtained by impregnating a PBO (poly-p-phenylenebenzobisoxazole) polymer fiber having a Young's modulus of 180 GPa with a polyester-based resin is applied. The In addition, as high intensity | strength FRP, glass fiber, carbon fiber, etc. of an inorganic fiber can also be used. Regarding the elongation rigidity of the optical cable 20c of Example 2-3, high-strength fibers having the same material and dimensions as those of Example 2-2 in FIG. 10 are provided. Therefore, the allowable tension of the optical cable 20c is 94 N even in the case of the low-strength optical fiber core wire 11 having a screening level as low as 0.3% and capable of extending only 0.2%. The tensile tension of 50 N or a general allowable tension of 70 N can be exceeded.

  Regarding the bending performance of the cable 20c, high-strength fibers are impregnated with a polyester matrix resin. Therefore, unlike Example 2-2 in FIG. 10 in which the periphery of the high-strength fiber bundle is suppressed by a soft thermoplastic resin, the bending performance is such that when the cable 20c is bent, the high-strength fiber is in the longitudinal direction. The strain cannot be relaxed. Therefore, the high strength FRP rod-shaped member is formed so that the thickness in the direction orthogonal to the arrangement direction of the optical fiber core wires 11 (that is, the bending direction on the short side) can withstand a predetermined bending test. It is preferable.

  Here, “withstands a predetermined bending test” means that, as shown in FIG. 12, the breaking strength of the optical cable is 50 N or more after being bent 100,000 times under the condition of a radius of curvature of 9 mm and a right angle of 90 °. Means. In addition, the “thickness that can withstand a predetermined bending test” means that the thickness in the bending direction of the FRP rod-shaped wire is 2 t and the bending radius is R, the outermost (innermost) side of the FRP rod-shaped wire is Although a strain of t / (R + t) is generated, it means a thickness that can withstand this strain and has a necessary minimum strength. For example, by making the rod-like member into a flat shape with a reduced thickness in the bending direction, a predetermined tensile tension can be secured and the strain can be reduced. FIG. 12 is a diagram for explaining a test method for bending performance as durability performance of an optical cable.

  Basically, if high-strength fibers having a breaking elongation of 2% or more are applied to the tension member 17b, the entire high-tensile fibers are flattened when the optical cable 20c is bent, and breakage due to bending can be prevented. Assuming that a portion of a high-strength FRP rod-shaped member having a large strain is partially broken, the high-strength fibers are not all broken. Although the high-strength fibers are integrated with each other through the matrix resin, the matrix resin has a modulus of elasticity that is two orders of magnitude lower than that of the high-strength fibers and is easily broken. Therefore, when some high-strength fibers break, the matrix resin around the broken high-strength fibers is also broken, and the high-strength fibers that are not broken do not break at the same time.

  Regarding the bending performance of the optical cable 20c, the high-strength fibers are easier to break than in Example 2-2 in FIG. 10, but the high-strength fibers having a high Young's modulus are integrated with a matrix resin, so that the anti-shrinkage body Also fulfills the function. Therefore, when the optical cable 20c is used at a low temperature, it resists low-temperature shrinkage of a thermoplastic resin having a large linear expansion coefficient, and reduces an increase in loss due to microbending of the optical fiber core wire 11 in the cable jacket 16. be able to.

  The polyester resin impregnated in the high-strength fiber may be an ultraviolet curable acrylic resin or a low viscosity thermoplastic resin as long as the thermosetting resin penetrates between the fibers. With respect to the mountability of the optical connector 9, the optical fiber core wire 11 and the high-strength fiber (tension member 17b) constituting the optical cable 20c and the thermoplastic resin of the cable jacket 16 are integrated in close contact with each other. The cable jacket 16 can be fixed simply by gripping it with the gripping portion of the optical connector 9, and can be easily attached.

(Comparative Example 2-1)
Next, the structure of the first comparative example (Comparative Example 2-1) of the optical cable 20 according to the second embodiment will be described. The optical cable of Comparative Example 2-1 is shown in FIG. 14A and has a cross-sectional structure.

  The optical cable of Comparative Example 2-1 has two optical fiber cores 2 arranged in a row in the same manner as in Example 2-1 of FIG. 9, and outer diameters as tension members 3 on both sides of these optical fiber cores 2. A 0.4 mm steel wire is disposed, and the optical fiber core wire 2 and the tension member 3 are integrally covered with a 2 mm × 3 mm cable jacket 4. A multimode glass fiber having a core diameter of 50 μm and a clad diameter of 125 μm is applied to the glass fiber of the optical fiber core 2 as in Examples 2-1 to 2-3. On the outer periphery of the glass fiber, a coating layer made of an ultraviolet curable acrylate resin having an outer diameter of 250 μm from the surface of the glass fiber is formed. The cable jacket 4 is formed by thoroughly extruding a soft 100 MPa polyolefin resin.

  The Young's modulus of the steel wire of the tension member 3 is larger than that of the PBO fiber, the elongation stiffness (ES product) of the steel wire is 53 kN, and the elongation stiffness of the fiber glass portion is more than an order of magnitude more than 1.7 kN. In the case of a steel wire, the allowable elongation of the steel wire itself is a rule, and the allowable elongation of the optical cable is only 0.3%. When calculated with an allowable elongation of 0.3%, the allowable tension of the optical cable is about 160 N, which can exceed the general allowable tension 70 N of the optical cable used indoors. In the case of a steel wire, since the allowable elongation of the steel wire itself is only 0.3%, there is no point in applying a high-strength optical fiber core with 1.5% screening, for example. As for the bendability of the optical cable, as described in the section of the problem, the steel wire causes metal fatigue, so the bending performance is low. When the cable is bent with a bending radius of R9 mm, the steel wire portion causes metal fatigue and is 2000 times. Disconnected at a degree.

(Comparative Example 2-2)
A second comparative example (Comparative Example 2-2) of the optical cable 20 according to the second embodiment has a cross-sectional structure shown in FIG.

  In the optical cable of Comparative Example 2-2, two optical fiber cores 2 are arranged in a row in the same manner as in Example 2-1 of FIG. 9, and the tension members 3 are arranged on both sides of the optical fiber cores 2 as outer members. A twisted steel wire obtained by twisting nine steel wires having a diameter of 0.17 mm is disposed, and the optical fiber core wire 2 and the tension member 3 are integrally covered with a cable jacket 4 of 2 mm × 3 mm. As in the case of Examples 2-1 to 2-3, a multimode glass fiber having a core diameter of 50 μm and a cladding diameter of 125 μm is applied to the glass fiber of the optical fiber core 2. On the outer periphery of the glass fiber, a coating layer made of an ultraviolet curable acrylate resin is formed from the surface of the glass fiber to an outer diameter of 250 μm. The cable jacket 16 is formed by solid extrusion molding of a soft (Young's modulus 100 MPa) polyolefin resin.

  The elongation rigidity (ES product) of the stranded steel wire of the tension member 3 is 86 kN, and even in the case of the stranded steel wire, the allowable elongation of the stranded steel wire itself is a rule, and the allowable elongation of the optical cable is only 0.3%. When calculated with an allowable elongation of 0.3%, the allowable tension of the optical cable is about 260 N, which can exceed the general allowable tension 70 N of the optical cable used indoors. Regarding the bendability of the optical cable, similarly to Comparative Example 2-1, even when thin steel wires of 0.17 mm are used, metal fatigue is inevitable. Therefore, in the case of the bending radius R9 mm, the number of times until disconnection increased compared with Comparative Example 2-1, but it was still disconnected by bending about 10,000 times.

  Next, FIG. 13 illustrates determination of bending performance as the durability performance of each of Examples 2-1 to 2-3, Comparative Example 2-1, and Comparative Example 2-2 of the optical cable 20 according to the second embodiment. It is a table | surface which shows a result.

  In FIG. 13, the optical cables of Examples 2-1 to 2-3, Comparative Example 2-1, and Comparative Example 2-2 having the above-described structures are bent at a bending radius of R9 mm and 90 ° left and right. (See FIG. 12) shows the cable tension when bent 100,000 times. In Examples 2-1 to 2-3, the allowable elongation of the fiber is determined from the viewpoint of the lifetime of the optical fiber, and the cable tension at the time of 10% elongation is shown. About the comparative example 2-1 and the comparative example 2-2, since the allowable elongation of a steel wire becomes a rule, it is shown by the cable tension at the time of 0.3% elongation.

  As can be seen from the results shown in FIG. 13, in Examples 2-1 to 2-3 of the second embodiment, although the cable tension after the bending test is slightly lower than before the bending test, Usually, the tensile tension of 50 N in indoor work or the general allowable tension of 70 N is exceeded. On the other hand, the optical cables of Comparative Example 2-1 and Comparative Example 2-2 were both disconnected during the bending test.

  From the above description of the present invention, it is apparent that the present invention can be modified in various ways. Such modifications cannot be construed as departing from the spirit and scope of the invention, and modifications obvious to one skilled in the art are intended to be included within the scope of the following claims.

  The optical cable according to the present invention is applicable to an optical wiring that optically connects a plurality of information devices installed indoors or in a vehicle.

It is a figure for demonstrating the basic structure (cross-section structure) and impact resistance test method of 1st Embodiment of the optical cable which concerns on this invention. It is a figure for demonstrating the cross-section of the optical fiber core wire applied to the 1st Example (Example 1-1) of the optical cable which concerns on 1st Embodiment. It is a figure for demonstrating the cross-section of the optical fiber core wire applied to the 2nd Example (Example 1-2) of the optical cable which concerns on 1st Embodiment. It is a figure for demonstrating the cross-section of the optical fiber core wire applied to 3rd Example (Example 1-3) of the optical cable which concerns on 1st Embodiment. It is a figure for demonstrating the cross-section of the optical fiber core wire applied to the 4th Example (Example 1-4) of the optical cable which concerns on 1st Embodiment. It is a figure for demonstrating the cross-section of the optical fiber core wire applied to the 5th Example (Example 1-5) of the optical cable which concerns on 1st Embodiment. First to fifth examples (Example 1-1 to Example 1-5), a first comparative example (Comparative example 1-1), and a second comparative example (Comparative example 1) of the optical cable according to the first embodiment. -2) It is a table | surface which shows the determination result of an impact characteristic and a temperature characteristic as each durable performance. It is a figure which shows the basic structure (cross-section structure) and external appearance of 2nd Embodiment of the optical cable which concerns on this invention. It is a figure for demonstrating the cross-section of the 1st Example (Example 2-1) of the optical cable which concerns on 2nd Embodiment. It is a figure for demonstrating the cross-section of the 2nd Example (Example 2-2) of the optical cable which concerns on 2nd Embodiment. It is a figure for demonstrating the cross-section of the 3rd Example (Example 2-3) of the optical cable which concerns on 2nd Embodiment. It is a figure for demonstrating the test method of bending performance as durability performance of an optical cable. First to third examples (Example 2-1 to Example 2-3), a first comparative example (Comparative example 2-1), and a second comparative example (Comparative example 2) of the optical cable according to the second embodiment -2) It is a table | surface which shows the determination result of bending performance as each durability performance. It is a figure which shows the cross-section of the conventional optical cable.

Explanation of symbols

  10, 20, 20a, 20b, 20c ... optical cable, 11, 11a, 11b, 11c, 11d, 11e ... optical fiber core wire, 12 ... glass fiber (bare fiber), 13 ... coating layer, 13a ... primary coating (soft layer) ), 13b ... secondary coating (hard layer), 14 ... colored layer, 15 ... protective layer, 16 ... cable jacket, 17, 17a, 17b, 17c ... tension member, 18 ... metal rod, 19 ... weight.

Claims (11)

An optical fiber core having a bare fiber mainly composed of quartz glass and a coating layer provided on an outer periphery of the bare fiber and made of an ultraviolet curable resin, wherein the coating layer has a first coating having a Young's modulus of 200 MPa or more. Including optical fiber core wire, and
A cable jacket having a minimum thickness of 0.7 mm or more provided on the outer periphery of the optical fiber core, and having a flame retardance of V2 or more according to UL standards, and a Young that is equal to or more than the first coating. And a cable jacket made of a halogen-free thermoplastic resin.   The optical cable according to claim 1, wherein the first coating is in direct contact with the surface of the bare fiber.   The coating layer of the optical fiber includes a second coating provided between the bare fiber and the first coating, and the second coating has a Young's modulus of 0.5 to 2 MPa. The optical cable according to claim 1.   The optical cable according to claim 3, further comprising a colored layer provided on an outer periphery of the optical fiber core, wherein the colored layer has a breaking elongation of 10% or more.   The optical cable according to claim 4, further comprising a protective layer provided on an outer periphery of the colored layer, wherein the protective layer is made of an ultraviolet curable resin having a Young's modulus of 50 to 300 MPa. The optical cable does not include a tension member, and
The optical cable according to claim 1, wherein the cable jacket has a Young's modulus of 500 MPa or more and 1500 MPa or less. A connecting part attached to the cable jacket to be located at the end of the optical cable, and
The cable jacket is integrated with an optical fiber core so that a total tensile tension of the optical cable when the optical cable is extended by 1% along the longitudinal direction thereof is 50 N or more. The optical cable according to claim 1. A bare fiber mainly composed of quartz glass, an optical fiber core wire provided on the outer periphery of the bare fiber and having a coating layer made of an ultraviolet curable resin; and
A cable jacket provided on the outer periphery of the optical fiber core and having a minimum outer diameter of 4 mm or less and containing no metal wire, and the optical cable when the optical cable is extended by 1% along its longitudinal direction An optical cable including a cable jacket integrated with an optical fiber core wire so that the total tensile tension of the optical fiber becomes 50 N or more.   A high-strength fiber bundle integrally covered with the optical fiber core wire and covered with a cable jacket, wherein the cable outer sheath has a density of 50 N / cm to 900 N / cm for pulling the high-strength fiber bundle from the cable jacket. The optical cable according to claim 1, further comprising a high-strength fiber bundle covered with a cover.   The cable jacket has a total tensile tension of the optical cable when the optical cable is bent 100,000 times with a radius of curvature of 9 mm and 90 ° left and right, and then the optical cable is extended by 1% along its longitudinal direction. 2. The optical cable according to claim 1, wherein the optical cable is integrated with an optical fiber core wire so as to be 50 N or more.   The optical cable according to claim 1, wherein the optical cable comprises a high-strength fiber bundle integrally covered with the optical fiber core wire and covered with a cable jacket, and having high conductivity.

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