JP2002350696A - Optical fiber cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber cable which has flexibility, easy handling property, water proofing property, rat preventing property and chemical resistance, which can be easily optically connected and which has preferable laying property. SOLUTION: The optical fiber cable has a core layer having a plurality of plastic optical fibers 2 and a high tensile reinforcing member 3, a buffer layer 5 formed by winding fluorocarbon resin tapes to surround the core layer, and a protective layer 6 formed around the buffer layer by melt extrusion coating of a fluorocarbon resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an FTTH for connecting an optical fiber from a communication trunk to an office or each home.
The present invention relates to an optical fiber cable suitably used for (fiber to the home) and the like.

[0002]

2. Description of the Related Art In recent years, with the development of advanced information communication, an optical fiber network has been set up around a communication trunk, and high-speed, large-capacity communication by optical transmission has become widespread. For such communication trunks, single-mode silica-based optical fibers are used for various reasons such as reduction of optical transmission loss, and high-speed data transmission of several tens of gigabit class is possible. However, when connecting to the data communication device in the office or each home from this silica optical fiber of the communication trunk,
In the case of connecting using the same silica-based optical fiber, the flexibility is poor and the handling is difficult, and the diameter of the core of the silica-based optical fiber is very small, about several μm. There is a problem that connection is very costly, which is one of the obstacles to the spread of connection to data communication devices in offices or homes.

In order to facilitate branching and connection from such a quartz optical fiber of a communication trunk to a data communication device in an office or each home, the core has a larger diameter than that of the quartz optical fiber. It has been proposed to use a plastic optical fiber which is excellent in branching and connecting properties, has high flexibility, and is excellent in handleability.

[0004] Cables are used as plastic optical fibers. The cable is usually one in which a plurality of optical fibers are housed in a synthetic resin tube, and is manufactured by extruding a molten synthetic resin around the plurality of optical fibers to form a tube by coating. Hereinafter, this tubular portion of the cable is referred to as a protective layer. The protective layer is made of a polyolefin resin, a vinyl chloride resin, or the like, and a protective layer formed of a melt-moldable fluororesin is also known. The plastic optical fiber housed in the optical fiber cable is a plastic optical fiber or a plastic optical fiber cord. A plastic optical fiber cord is a plastic optical fiber wire coated with resin.
Examples of the coating resin include a thermoplastic resin such as polymethyl methacrylate and polyolefin, and a cured product of a curable resin such as an ultraviolet curable resin.

As an optical fiber cable containing a plastic optical fiber, an optical fiber cable having an inner layer made of a heat-insulating fluororesin and a protective layer made of a melt-moldable fluororesin is known (Japanese Patent Publication No. 59-28882). . This optical fiber cable is an optical fiber cable in which a protective layer is formed on an optical fiber wound with a porous fluororesin tape by a melt-extrusion coating method of a fluororesin.
The layer formed by winding the porous fluororesin tape blocks the heat applied to the optical fiber in the melt extrusion coating, and has an effect of preventing the physical properties of the plastic optical fiber from deteriorating.

[0006] When branching or connecting from a quartz optical fiber of a communication trunk to a data communication device in an office or home using an optical fiber cable containing a plastic optical fiber, from the viewpoint of space or beauty, etc. For example, an optical fiber cable may be laid in a sewer pipe. In this case, compared to the physical properties required for ordinary optical fiber cables, high mechanical properties such as higher tensile strength, harsh sewer environment such as waterproof, ratproof and chemical resistance, etc. Withstand, that is, good layability is required.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object the purpose of having high mechanical properties and flexibility, easy handling, waterproofness, and water resistance. While having chemical properties, it can easily make optical connection,
An object of the present invention is to provide an optical fiber cable having good layability. Further, in consideration of the case of laying in a sewer pipe, rat-proofing can be provided.

[0008]

Means for Solving the Problems The present invention is the following invention which achieves the above object. A core layer having a plurality of plastic optical fibers and a tensile strength reinforcing member, a buffer layer formed by winding a fluororesin tape so as to surround the core layer, and a fluororesin provided outside the buffer layer and provided An optical fiber cable having a protective layer formed by a melt extrusion coating. A buffer layer is formed by winding a fluororesin tape around a core material having a plurality of plastic optical fibers and a tensile strength reinforcing member, and then forming a protective layer outside the buffer layer by melt extrusion coating of the fluororesin. A method for manufacturing an optical fiber cable.

The plastic optical fiber in the optical fiber cable of the present invention may be a gradient index plastic optical fiber made of an amorphous transparent fluororesin having substantially no C--H bond, as described later. preferable.
Further, it is preferable that the tensile strength reinforcing member comprises a bundle of continuous long fibers. Further, it is preferable that an inclusion having a ratproofing agent is present in the space of the core layer of the optical fiber cable.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a plastic optical fiber, a gradient index (GI) plastic optical fiber,
There are a graded index (SI) plastic optical fiber, a single mode plastic optical fiber, a multi-core plastic optical fiber, and the like, and the plastic optical fiber in the present invention may be any of these. Examples of the material of the plastic optical fiber in the present invention include polymethyl methacrylate resin and polycarbonate resin, and an optical fiber using such a material can be used as the optical fiber in the present invention. However, a plastic optical fiber made of these materials is made of a resin having a C—H bond in a molecule.
Harmonic absorption due to stretching motion of -H bonds occurred in a specific wavelength region such as an infrared or visible light region, and transmission loss in that wavelength region was large. In addition, since these resins have high hygroscopicity, there is a problem that transmission loss greatly changes depending on environmental conditions such as temperature conditions. As a result, in the wavelength region used for optical transmission, it has not been possible to use an infrared wavelength region that enables high-speed transmission, especially in the order of several gigabits.

When such a conventional plastic optical fiber is used for branching and connecting from a quartz optical fiber of a communication trunk to a data communication device in an office or each home, for example, recently, it is used in an office or each home. When used for connection to the Internet, which has become very popular, there is a problem that it is difficult to sufficiently meet the demand for high-speed transmission of large-volume data such as moving images in addition to voice and still images on the Internet.

As the plastic optical fiber in the present invention, a plastic optical fiber made of an amorphous transparent fluororesin having substantially no C--H bond is preferable.
This plastic optical fiber does not absorb in the infrared or visible light region, and has particularly excellent characteristics as a plastic optical fiber for communication.

As the amorphous transparent fluororesin, a fluororesin made of a fluoropolymer having a ring structure in the main chain, particularly a fluororesin made of a fluoropolymer having a fluorinated aliphatic ring structure in the main chain is preferable. Examples of such a plastic optical fiber using an amorphous fluororesin are disclosed in JP-A-8-5848 and JP-A-11-1670.
30 and a SI type plastic optical fiber described in JP-A-4-1704. The GI plastic optical fiber has a smaller mode dispersion than the SI plastic optical fiber, and is particularly suitable for high-speed data transmission of several gigabits or more.

The plastic optical fiber in the present invention may be a wire or a cord. For code,
The material of the coating layer is not particularly limited, and the above-mentioned polymethyl methacrylate and polyolefin can be used. Further, a fluorine resin such as an ethylene / tetrafluoroethylene copolymer or a fluorine resin such as the above-mentioned amorphous fluorine resin can also be used. The material of the coating layer, which is particularly preferable in terms of flexibility, waterproofness, chemical resistance and the like, is a fluororesin, and among them, the amorphous fluororesin is preferable.

In the present invention, a plurality of plastic optical fibers are accommodated in the core layer of the cable. Preferably, 2 to 16 optical fibers are accommodated. Further, a tensile strength reinforcing member is accommodated in the core layer. The reinforcing member is for preventing the optical fiber from being cut or deformed by the tensile stress of the cable, and a linear reinforcing member is arranged in the length direction of the cable. The reinforcing member in the present invention is preferably a continuous long fiber made of an inorganic fiber such as a carbon fiber or a glass fiber or a synthetic fiber such as an aramid fiber, and may be a reinforcing metal wire such as a steel wire. In particular, a linear body obtained by binding continuous fibers having high tensile strength with a binder or the like is used.

[0016] It is preferable that an intervening material is further present in the space excluding the optical fiber and the reinforcing member of the core layer. The inclusions are used to fix the plastic optical fiber and the reinforcing member in the cable and keep the cross-sectional shape of the cable constant. In addition, various functions such as cushioning property and heat insulation property can be provided. As the material of the inclusion, resin,
Foam resin, fiber (continuous long fiber bundle or non-directional fiber aggregate)
and so on. In particular, fiber bundles are preferable because they are easy to handle in cable manufacturing and have a reinforcing effect. This fiber may have a lower tensile strength than the fiber of the reinforcing member.

A layer in which inclusions are present (hereinafter referred to as an intervening layer)
It is also preferable that a rat repellent such as a rat repellent or a rodenticide be present in order to further provide rat-proofing properties. For example, the rodent-preventing agent can be present in the intervening layer by a method such as mixing microcapsules containing a rodent-preventing agent such as capsaicin into the inclusion, or impregnating or applying the rodent-preventing agent to the inclusion.

A buffer layer is formed by winding a fluororesin tape around a plastic optical fiber (and reinforcing members and inclusions). As a material for the fluororesin tape, polytetrafluoroethylene (PTFE) is preferable, but not limited thereto, and tetrafluoroethylene / hexafluoropropylene copolymer (FEP),
Tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), ethylene / tetrafluoroethylene copolymer (ETF
E), fluororesins such as ethylene / chlorotrifluoroethylene copolymer (ECTFE) can be used. A particularly preferred tape is a tape of expanded porous PTFE.

When the tape is wound around the plastic optical fiber and the reinforcing member (and the inclusion), it is preferable that the tape is wound so that the ends in the width direction of the tape overlap with each other. It may be wound so that the ends in the direction abut, or the ends in the width direction may be wound with some gap. Further, two or more tapes may be wound to form a buffer layer having a multilayer structure. In the present invention, the buffer layer preferably has a structure including two or more (preferably 2 to 6) wound tapes.

The buffer layer functions as a chemical, mechanical or thermal buffer layer. Also, when a plurality of plastic optical fibers are twisted, when the tape is wound in the same direction as the twist direction, if the cable is bent, the slip direction of the tape becomes the forward direction with the twist direction of the optical fiber. Therefore, the bending of the cable is unlikely to be a stress for clamping the plastic optical fiber. Therefore, there is also an effect that loss of transmitted light due to local stress applied to the plastic optical fiber is reduced.

After forming the buffer layer around the plastic optical fiber, a protective layer made of fluororesin is formed on the surface of the structure. The protective layer is formed by melt extrusion coating of a melt-moldable fluororesin. Examples of the fluorine resin that can be melt-molded include FEP, E,
TFE, PFA and the like are preferred. Particularly, ETFE which can be molded at a relatively low temperature is preferable. The physical properties of the plastic optical fiber may be degraded by the heat during melt molding. However, in the present invention, the buffer layer prevents this heat conduction,
Prevents deterioration of physical properties of plastic optical fiber. Also,
Even in the case where a substance having low heat resistance (such as the rat-proofing agent) exists in the intervening layer, the influence on such a substance can be reduced by the heat insulating effect of the buffer layer.

The cable of the present invention can be manufactured by the method described above. That is, the buffer layer is formed by wrapping the tape around a plastic optical fiber or a core material in which the reinforcing member and the inclusion are bundled, and then a fluororesin is melt-extruded in a ring around the outer periphery of the buffer layer. It is manufactured by forming a protective layer. This manufacturing method is usually performed continuously, and a continuous cable is obtained.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments with reference to the accompanying drawings. FIG. 1 is a sectional view of the optical fiber cable of the present invention. Referring to FIG. 1, there is shown an optical fiber cable 1 according to the present invention. The optical fiber cable 1 is provided with a pair of twisted plastic optical fiber cords (diameter 0.5 mm) at a central portion thereof. A reinforcing member 3 made of carbon fiber "Treca" (trademark, manufactured by Toray Industries, Inc.) is disposed between the plastic optical fiber cords. The plastic optical fiber cord comprises a plastic optical fiber 2 (diameter 0.23 mm) and a coating layer 7 covering the same.

An intervening layer 4 is provided around the pair of plastic optical fiber cords and the reinforcing member 3.
The intervening layer 4 is "Vectran" which is a polyarylate fiber.
(Trademark, manufactured by Kuraray Co., Ltd.). In addition, microcapsules containing capsaicin are mixed in the intervening layer 4. Further, as shown in FIG. 1, the pair of plastic optical fiber cords,
And around the intervening layer 4, a width of 7.1 mm and a thickness of 78 μm
buffer layer 5 formed by winding two layers of tape made of expanded porous PTFE “Gore-Tex” (trade name, manufactured by Gore Co., Ltd.)
It is formed as. Here, the winding direction of the tape and the twisting direction of the plastic optical fiber cord 2 are the same.

A protective layer 6 having a thickness of 0.1 mm is formed on the outer periphery of the buffer layer 5 by melt extrusion of ETFE. The plastic optical fiber 2 is disclosed in
It is made of a GI plastic optical fiber described in Japanese Patent No. 5848 and Japanese Patent Application Laid-Open No. 11-167030. That is, it is a GI-type plastic optical fiber obtained by using an amorphous transparent fluororesin having substantially no C—H bond obtained by cyclopolymerization of perfluoro (butenyl vinyl ether) and a refractive index adjuster. The coating layer 7 is made of the same amorphous transparent fluororesin as described above.

The optical fiber cable shown in FIG. 1 is manufactured continuously by the following method. A pair of optical fiber cords and a polyarylate fiber bundle (pre-mixed with microcapsules containing capsaicin) are wound around a reinforcing member made of carbon fiber, and an expanded porous PTFE tape is further placed thereon. The core body is formed by winding two layers in the same direction as the winding direction. Next, the core is
It is introduced into a TFE melt extrusion molding apparatus, and molten ETFE is extruded annularly around the core body to obtain a desired optical fiber cable.

As described above, in the optical fiber cable shown in FIG. 1, the plastic optical fiber 2 for transmitting an optical signal is made of fluororesin having no C--H bond in the molecule. The expanded porous P in which the buffer layer 5 disposed around the optical fiber 2 is made of fluororesin.
The protective layer 6, which is wound around with a TFE tape and further covered therearound, is also made of fluororesin, and is entirely made of fluororesin plastic, so that it is flexible and easy to handle. , Optical connection can be easily made, and it can be equipped with waterproof, ratproof, chemical resistance, high speed, large capacity communication, and good layability in environmental resistance. An optical fiber having:

[0028]

As described above, according to the optical fiber cable of the present invention, the expanded porous PTFE tape in which the buffer layer disposed around the plastic optical fiber for transmitting the optical signal is a fluororesin. And wound with
Since the protective layer further covered therewith is also made of a fluororesin, it is rich in flexibility, easy to handle, and can be easily optically connected. It can also have chemical resistance. Therefore, in addition to the physical properties required for an ordinary optical fiber cable, the optical fiber cable has excellent performance as an optical fiber cable laid in a sewer sewer because it withstands a severe sewer environment.

[0029]

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view of an embodiment of an optical fiber cable according to the present invention.

[Explanation of symbols]

 1: optical fiber cable 2: plastic optical fiber wire 3: reinforcing member 4: intervening layer 5: buffer layer 6: protective layer 7: coating layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masaki Narutomi Asahi Glass Co., Ltd., 1-12-1 Yurakucho, Chiyoda-ku, Tokyo (72) Inventor Minoru Sawada 961-20, Fukuda, Kasama-shi, Ibaraki Pref. (72) Inventor Katsuo Shimozawa 961-20 Fukuda, Kasama City, Ibaraki Pref.Jun Kogyo Co., Ltd. 961-20 Fukuda, Kasama City Junko Co., Ltd. F-term (reference) 2H001 BB06 DD04 DD15 DD35 FF00 KK03 KK06 KK07 KK17 KK22

Claims (5)

[Claims] 1. A core layer having a plurality of plastic optical fibers and a tensile strength reinforcing member, a buffer layer formed by winding a fluororesin tape so as to surround the core layer, and provided outside the buffer layer. An optical fiber cable having a protective layer formed by a melt-extrusion coating of a fluororesin. 2. The optical fiber cable according to claim 1, wherein the plastic optical fiber is a gradient index plastic optical fiber made of an amorphous transparent fluororesin having substantially no C—H bond. 3. The optical fiber cable according to claim 1, wherein the tensile strength reinforcing member comprises a bundle of continuous long fibers. 4. The optical fiber cable according to claim 1, wherein an inclusion having a rat-proofing agent is present in the space of the core layer. 5. A buffer layer is formed by winding a fluororesin tape around a core having a plurality of plastic optical fibers and a tensile strength reinforcing member, and then forming a buffer layer by melt extrusion coating of the fluororesin. Forming a protective layer on the optical fiber cable.