JPH0320704A - Optical fiber cord - Google Patents

Abstract

PURPOSE:To allow the common use of the optical fiber indoors and outdoors by providing an inside layer consisting of a thermoplastic resin forming a space part to be inserted with optical communication wires and an outside layer consisting of a weather resistant thermoplastic resin enclosing this layer and forming the outside layer so as to allow the easy stripping thereof. CONSTITUTION:Tensile wires 2 formed by coating steel cords 1 consisting of twisted and doubled steel wires with a polyethylene (PE) resin are disposed. A fire-retardant PE resin is then melt-extruded from a rectangular die to form the space part 3 for housing optical fibers. The rectangular inside layer 4 to cover this part is formed. Further, the inside layer 4 is covered strippably with a weather-resistant PE resin to form an outside layer 5. Notches 7 are provided on the outer periphery of the positions corresponding to the angle parts of the inside layer 4. Two-fiber coated tape fibers 8 are inserted to the optical fiber cords. The optical fiber cord is used in the state of having the outside layer at the time of using the same outdoors and is usable by stripping the outside layer in the case of using the cord indoors. The common use of the cord as the outdoor wire and the indoor wire is thus possible.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is directed to branching a specific optical fiber core (including bare wire or tape fiber) with a single fiber or a small number of fibers from an optical fiber cable to a terminal device. The present invention relates to an optical fiber cord that is suitable for use in connecting to a network, and that can be used for both outdoor and indoor lines.

(Background of the Invention and Its Issues) In optical fiber communication systems, optical fiber cables made up of a large number of optical fibers are used. In m, it is laid in a conduit or overhead, and in the terminal system,
Specific optical fiber cores (including bare wires or tape cores) having a single core or a small number of cores are branched out from this optical fiber cable, and used by being connected to a predetermined device or device.

Conventionally, in this branch connection, an outdoor optical fiber cord line is used in the outdoor area, and an indoor line is used in the indoor area. In this case, outdoor wires are required to be weather resistant because they are exposed to the outside air, and indoor wires are often required to be flame retardant from the viewpoint of fire prevention.From these points, conventionally, the above-mentioned As usual, outdoor lines and indoor lines use different structures, which requires a connection box and connection work to connect the lines, and there is a risk that the connection will increase transmission loss. was there.

The present invention has been made in view of the above-mentioned problems, and includes:
The present invention was completed by intensive study on the structure of an optical fiber cord that can connect an optical fiber and a terminal device continuously without any connection in the middle.

<Means for Solving the Problems> In order to achieve the above object, the present invention includes a space through which an optical communication line is inserted, an inner layer made of a thermoplastic resin forming this space, and a thermoplastic resin disposed in the inner layer. and an outer layer made of a thermoplastic resin with excellent weather resistance surrounding the inner layer, and the outer layer is configured to be separable from the inner layer.

In the optical fiber cord of the present invention, the shape of the space through which the optical communication line such as the optical fiber strand or core wire or tape core wire is inserted is not particularly limited, and may be rectangular or circular. In addition, at least the tensile strength wires arranged in the inner layer are single steel wires having a thickness or number determined according to the required physical properties and having appropriate flexibility. Examples include twisted steel wire and other metal wires, FRP or FRTP wires made by bonding high-strength, low-elongation reinforcing fibers with resin, polyoxymethylene, thermotropic liquid crystal, etc., and these are coated with a primary coating layer in advance. It is preferable that the inner layer be integrated with the inner layer.

Furthermore, by arranging tensile strength wires similar to those used in the inner layer in the outer layer, the outdoor wire wiring can be made stronger.

In particular, when lateral pressure is applied to the space, it is desirable to arrange tensile strength lines on both sides of the space.

The thermoplastic resin forming the inner layer may be used for indoor wiring, so it is preferably flame-retardant, and the flame-retardant index such as oxygen index satisfies the specifications, for example, the oxygen index is 27 or higher. When using a tensile strength wire with a primary coating, it is preferable to use a material that is compatible with the coating layer.

The outer shape of the inner layer is preferably a flat rectangular shape when the inner layer is used indoors, such as under a floor, but it is not limited to this shape, and any shape can be selected.

On the other hand, since the outer layer is used outdoors and is exposed to sunlight, wind and rain, weather resistance is required, so a thermoplastic resin mixed with a weathering agent, carbon plaque, etc. is used.

Since the optical fiber cord of the present invention is used both outdoors and indoors, the thermoplastic resins of the outer layer and inner layer are selected to satisfy different performances, and the outer layer coating is peeled off to make it usable indoors. It is configured as possible. As a means to facilitate this peeling, there are structures in which the inner and outer layers are not fused together in consideration of the coating conditions of the outer layer, or a structure in which silicone, lubricant, or other material with mold releasability is added to and mixed with the thermoplastic resin of the outer layer, and A structure in which at least one notch is provided in the outer layer to make it easier to peel off when an external force is applied; Examples include a structure in which a fiber bundle or a string-like material is placed in the fiber bundle and the outer layer is peeled off by pulling the fiber bundle, and a structure in which these are used in combination as appropriate.

Note that as the base thermoplastic resin used for the inner layer and outer layer, polyethylene resin is recommended from the viewpoint of physical properties, economical efficiency, etc., but is not limited thereto.

<<Operation and Effect>> When the optical fiber cord of the present invention is used outdoors, it can be used with an outer layer that is a coating for weather resistance, and when used indoors, the outer layer can be peeled off to expose the inner layer. Since the inner layer can be made of flame-retardant resin as necessary, it can be used both as an outdoor line and an indoor line, and it can also be used as a device for connecting outdoor lines and indoor lines, which was unavoidable in the past. Connection work can be omitted.

"Example} Hereinafter, the present invention will be explained using preferred embodiments.

Example 1 A steel cord 1 made by twisting five m-wires with a diameter of 0.22 mm was used, and after covering it with adhesive polyethylene resin (GAOO4 manufactured by Nippon Unicar Co., Ltd.), it was passed through a shaping device and removed. The diameter was adjusted to obtain a coated tensile strength wire 2 having a diameter of 0.81III1. A pair of coated tensile strength wires 2 are arranged on both sides at a predetermined interval, and are used as an optical fiber storage space 3.
x h − 0. 9 x 0. In order to form 9mI1, flame retardant polyethylene resin (
PE MT5-0699 CB manufactured by Dainichiseika Chemical Co., Ltd.
) was melt-extruded and coated with black) to form a rectangular protective pipe (inner layer) 4 with an outer diameter of 2×3 dimensions.

This protective vibe (inner layer) 4 is passed through a coating die using weather-resistant polyethylene resin (DFDJ-05 manufactured by Nippon Unicar Co., Ltd.).
88: Carbon plaque containing 2.6%) was coated to form the outer layer 5. When coating the outer layer 5, the outer surface of the protective pipe 4 is cooled with a double tube structure that allows cooling water to circulate, so that the resin surface of the inner layer 4 is melted by the molten resin when the outer layer 5 is coated. In order to prevent the interface 6 of both layers from fusing together, and to prevent the outer layer 5 from peeling off during use, four V-shaped holes are placed on the outer periphery of the inner layer 4 at positions corresponding to the corners. Notch 7 was formed.

The obtained optical fiber cord without optical fibers had an outer diameter of about 3.91II1, an opening of 0.2mu, and a depth of 0.1μ.
It had a notch 7 of ml, a unit weight Q of 13.5 g/m, and the inner layer 4 and outer layer 5 could be easily peeled off.

Unfortunately, the peel strength of the outer layer 5 of the optical fiber cord is determined by measuring the force required to peel off one of the four parts divided by the notch 7 at a peel angle of 90'' with respect to the longitudinal direction using a spring scale. It turned out to be 400g.

When a single mode double-core tape core wire 8 was inserted into this optical fiber cord with no optical fibers housed therein and various physical properties were measured, the following results were obtained.

The bending rigidity of the optical fiber cord was measured using a spring scale to determine the force required to bend it to a predetermined bending diameter.The bending stiffness was 310g for a bending diameter of 40+sφ, 130t for a 60φ bend, and 7 for a 80φ bending diameter.
The cord weighed 5g, 60g for 100φ, and had sufficient flexibility for this type of cord.

Further, when a compressive load was applied at a speed of 0.5+n/min from the outer periphery of the optical fiber cord to a width of 50 mm, and an increase in transmission loss was observed, no increase in transmission loss was observed up to 200 cmg.

On the other hand, using a DuPont impact tester, we dropped a flat-bottom impact center of 25 mm diameter and 1 mm from a height of 0.5 m, and observed an increase in transmission loss due to the impact, but even after repeated drops 20 times, No changes were observed.

Furthermore, when the wire was wound five times around mandrels (round bars) of various diameters and an increase in transmission loss was investigated, no increase in transmission loss was observed when the wire was 30 mmφ or more.

The tensile strength at break of the optical fiber cord of this example was 90 kgf (pulling speed 5/min), and the diameter at which buckling occurred when bent into a U-shape was 20 mm or less.

Example 2 An optical fiber cord having the same size and shape as Example 1 and having an aromatic polyamide fiber bundle 10 disposed at the tip of each notch 7 so as to be embedded in the outer layer 5 was produced. The outer layer 5 and inner layer 4 of the obtained optical fiber cord could be separated more easily than in Example 1 by pulling the fiber bundle 10 outward.

Example 3 A protective vibe (inner layer) 4 with an outer diameter of 1.8 × 3.0 mm obtained by the same manufacturing method as in Example 1 was coated with an outer layer 5 with an elliptical cross section of approximately 7 mm in major axis x 4 mm in minor axis. A pair of second coated tensile strength wires 11 made of 0.25+11×5 steel cords were also placed in the outer layer 5, and four notches 7 were formed on the outer periphery of the outer layer 5.

In this embodiment, each of the inner and outer layers 4 and 5 has a tensile strength of $
12 and 11, the notch 7 allows the outer layer 5 to
It can be easily peeled off, and when used outdoors, the strength at 0.5% elongation is 116 kg, which is sufficient for the tensile performance required for outdoor wires.

In addition. In the structure of this example, the tensile strength line 2 is 0.6
A 5φ KFRP wire is used, and the second tensile strength 1111 is 1.
When 0φ KFRP wire is used, the strength at 0.5% elongation is 80 kg, and when a 0.251 ll x 5 steel cord is used as the second tensile strength wire 11, the same strength is 82 kg. Strong (
70 kg or more).

Point Examples 4 and 5 In these two examples, the cross-sectional shape of the protective pipe 4 is approximately a perfect circle, and in Example 4, the outer layer 5 has an elliptical cross-section similar to Example 3, and in Example 5, the outer layer 5 has a square cross-section. Formed in cross section.

Further, in these two Examples, the second tensile strength Is11 was arranged in the outer layer 5 as in Example 3, and two notches 7 were provided in the outer layer 5 at opposing locations.

In each of the embodiments constructed in this way, the same effects as those of the above embodiments can be obtained.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the cross-sectional state of an optical fiber cord according to the first embodiment of the present invention, FIG. 2 is an explanatory diagram of the cross-sectional state of the optical fiber cord of the second embodiment, and FIGS. 3 to 5 are FIG. 7 is an explanatory diagram of the cross-sectional states of the optical fiber cords of the third to fifth embodiments. 1...Steel cord 2...Coated tensile strength wire 3...Space part 4...
...Inner layer 5...Outer layer 6...
... Interface 7 ... Notch

Claims (3)

[Claims] (1) A space through which an optical communication line is inserted, an inner layer made of thermoplastic resin forming this space, a tensile strength wire placed in this inner layer, and a heat resistant material with excellent weather resistance surrounding the inner layer. An optical fiber cord comprising an outer layer made of a plastic resin, the outer layer being configured to be separable from the inner layer. (2) The optical fiber cord according to claim 1, wherein at least one thin notch is formed in the outer layer. (3) The optical fiber cord according to claim 1 or 2, characterized in that a tensile strength wire is arranged in the outer layer.