JP2004333886A - Ripping cord for optical fiber cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ripping cord having an excellent identifying property from other materials in an optical fiber cable when embedded into the cable and an optical fiber cable embedded with the easily identifiable ripping cord. <P>SOLUTION: The ripping cord for the optical fiber cable comprises a plurality of collected yarn of two or more kinds of substantially different colors. Also, the optical fiber cable 5 is formed by covering the circumference of the optical fiber 4 with a buffer 3 and a resin enclosure 2 and embedding the ripping cord 1 into the resin enclosure 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, the color of the tear string for tearing the outer sheath of the optical fiber cable is set to two or more, and when the tear string is taken out from the cable, the tear string regardless of the color of the surrounding resin or fiber The present invention relates to a tear string for an optical fiber cable and an optical fiber cable.
[0002]
[Prior art]
In the optical fiber cable, the resin cover portion that covers the periphery of the optical fiber prevents water and particulate matter from entering the interior, and the rigidity of the cable is maintained. When connecting the optical fiber inside the cable to other cables or devices, it is necessary to take out the optical fiber from the inside of the cable. For this purpose, the surrounding resin cover must be removed. The resin cover part can be cut with a knife such as a knife. However, using a knife is highly likely to damage the optical fiber, and is not a preferable working method. For this reason, a tear string is embedded in the resin cover part along the longitudinal direction of the optical fiber cable, and the resin cover part is cut by pulling the tear string radially outward. By spreading the resin cover part, it can be taken out without damaging the optical fiber. Various fibers can be used for the tear string as long as they have a strength capable of tearing the resin cover portion, and polyester fibers, aromatic polyamide fibers and the like have been conventionally used.
[0003]
By the way, there are various types of cable structures for optical fiber cables, and some optical fibers include fibers such as polypropylene fibers as a buffer material around the optical fiber. In this case, the fiber of the buffer material is generally white or translucent, and the tear string made of polyester fiber or the like is also white or translucent, so it is difficult to distinguish between the tear string and the fiber of the buffer material, In particular, when working under environmental conditions where lighting is not sufficient, it was difficult to remove the tear string.
[0004]
For this reason, in order to make it easy to distinguish between the tear string and the fibers of the buffer material, it is also practiced to dye polyester fiber and use it as a tear string. Further, Patent Document 1 proposes to use colored fibers such as colored polypropylene fibers as the tear string and to color only the surface of the tear string in order to make the tear string and the cushioning material visible. ing. However, when fibers colored by dyeing or the like are used, there are problems of an increase in processing cost for coloring and a decrease in strength due to thermal processing during dyeing.
[0005]
Patent Document 2 and the like also describe the use of an aromatic polyamide fiber originally having a yellow color as a tear string. However, since the aromatic polyamide fiber is more expensive than the polyester fiber or polypropylene fiber, it has been a problem that the cost becomes high in order to obtain the same thickness as a normal tear string. Further, when the resin cover portion is yellow, it is difficult to distinguish the resin cover portion from the resin cover portion, and there is a disadvantage that the discrimination performance is poor.
[0006]
[Patent Document 1] JP 2002-350695 A [Patent Document 2] JP 9-101438 A
[Problems to be solved by the invention]
The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and even when the cushioning material and the resin cover have colors, the discrimination between them is good and the cost is low. It is another object of the present invention to provide a tearable string that can be made into an optical fiber cable, and further to provide an optical fiber cable provided with a tearable string having good discrimination.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention adopts the following specific items. That is,
(1) A tear string for an optical fiber cable composed of a plurality of two or more types of converging yarns of substantially different colors.
(2) The optical fiber cable according to the above (1), wherein the bundled yarn is a yarn twisted and a plurality of substantially different colors of the yarn twisted are twisted. For tear string.
(3) The tear for an optical fiber cable according to (1) above, wherein the bundled yarn is a twisted yarn and a braided cord formed by combining a plurality of substantially different colors of the twisted yarn. string.
(4) The tear string for an optical fiber cable according to any one of the above (1) to (3), wherein at least one kind of fibers having substantially different colors is a fiber having inherently unique colors.
(5) The optical fiber cable according to any one of the above (1) to (4), wherein at least one of the bundled yarns having substantially different colors is a yarn composed of high-strength fibers having a strength of 15 cN / dtex or more. For tear string.
(6) One type of bundled yarns of substantially different colors is a yarn composed of high-strength fibers having a strength of 15 cN / dtex or more, and the other type is polyester fibers, polypropylene fibers, and polyamide fibers. The tear string for optical fiber cables according to any one of the above (1) to (4), which is a yarn composed of one or more of the above.
(7) The tear string for an optical fiber cable according to the above (5) or (6), wherein the high-strength fiber is an aromatic polyamide fiber.
(8) In an optical fiber cable in which the periphery of the optical fiber is covered with a buffer material and a resin cover part, an optical fiber in which the tear string according to any one of (1) to (7) is embedded inside the resin cover part cable.
[0009]
The tear string for an optical fiber cable according to the present invention uses two or more kinds of substantially different bundling yarns of different colors, and the different colors can be recognized as different colors in the appearance of the tear string, so that the discriminability is improved. Even when the resin cover portion has a color, it is possible to easily find the position where the tear string exists. Furthermore, when using the fiber which has a peculiar color, such as production | generation, as a kind of fiber which comprises a tear string, it can use without coloring and can reduce coloring cost. Moreover, even when using high-priced high-strength fibers such as aromatic polyamide fibers, the cost of the tear string can be reduced by combining with other low-cost fibers.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[0011]
The kind of fiber used for the tear string for the optical fiber cable of the present invention is not particularly limited. For example, high-strength fiber having a strength of 15 cN / dtex or more, polyester fiber, polypropylene fiber, polyamide fiber, and the like can be used. Polyester fiber, aromatic polyamide fiber, aromatic polyester fiber, polyparaphenylene benzbisoxazole (PBO) fiber, etc. are particularly suitable. Of these fibers, the same type of fibers can be used with different colors. When two or more kinds of fibers are used, they can be used in any combination such as a combination of these fibers, a combination of these fibers with other fibers, a combination with other fibers, or the like.
[0012]
If high-strength fibers (strength 15 cN / dtex or more) such as aromatic polyamide fibers are used, the strength of the tear string can be improved. Alternatively, the tear string can be made finer while maintaining the required strength.
[0013]
The tear string of the present invention is embedded in the resin cover portion so as to tear the resin cover portion when the optical fiber is taken out from the optical fiber cable, and is embedded in a position as shown in FIG. 1, for example.
[0014]
FIG. 1 is a cross-sectional view showing an embodiment of an optical fiber cable in which the tear string of the present invention is embedded. In FIG. 1, the tear string 1 is buried one by one in a symmetrical position on the innermost layer side of the resin cover portion 2 in contact with the buffer material 3, and the resin cover portion 2 is torn by being pulled outward.
[0015]
When the tear string 1 is taken out, for example, the resin cover portion 2 at the end of the optical fiber cable is cut open by an arbitrary blade means such as a cutter. At this time, since the cushioning material 3 is likely to be in a defibrated state, if the tear string 1 and the cushioning material 3 are similar in color, it is determined whether the fibers exposed from the cut portion are the cushioning material 3 or the tear string 1. It is difficult to identify. However, when the tear string 1 and the cushioning material 3 have different colors, it is easy to identify them, so that the workability of taking out the tear string 1 is improved.
[0016]
Further, when the resin cover portion 2 at the end of the optical fiber cable is cut open, it is effective that the resin cover portion 2 and the tear cord 1 have different colors in order to find the position where the tear cord 1 is embedded.
[0017]
From this point, in order to improve the workability when the tear string is taken out from the optical fiber cable, the tear string of the present invention having two or more colors is a color different from that of the resin cover portion 2. It is effective to include colors different from those of the buffer material 3.
[0018]
Since the tear string of the present invention is a string composed of a plurality of two or more kinds of substantially different colors of focused yarns, the colors of each focused yarn can be changed as they are even in the state of a tear string. Can be recognized as. The bundling yarn may be a yarn imparted with bundling properties by, for example, a lower twisting or entanglement treatment, but it is preferable to add a bundling to make the bundling properties of the fibers dense. A tear string can be produced by twisting a plurality of under-twisted yarns of different colors into a twisted string, or by combining a plurality of under-twisted threads of different colors into a braided string. .
[0019]
Further, in order to improve the tearability, it is preferable that the fibers are tightly converged in the tear string, and the cross-sectional shape of the string is preferably close to a circle. Therefore, in the case of a twisted string structure, in a formula defined by twist coefficient = twist number (t / m) × √D (dtex) ÷ 3000 (where D in the formula is the fineness of the string) It is preferable to add a twist having a twist coefficient of 3.0 or more. In the case of a braid structure, it is preferable to insert a twisted yarn or the like at the center of the braid to maintain a circular cross section.
[0020]
As long as the colors of the plurality of types of bundling yarns constituting the tear string of the present invention are different, the bundling yarns may be used in combination with bundling yarns made of fibers colored by dyeing or the like. It may be used in a combination of yarns, or may be used in a combination of both bundling yarns.
[0021]
In particular, it is preferable to use a bundling yarn made of fibers having inherently unique colors as at least one kind of bundling yarns having substantially different colors. In this case, one type may be a bundled yarn of fibers that are generated using the color, and another type may be a bundled yarn of fibers dyed in other colors. As the fiber, a bundled yarn of other types of fibers having different colors may be used. Thus, if the fiber which does not pass coloring processes, such as dyeing, is used, the manufacturing cost required for coloring can be reduced. That is, if the tear string 1 is constituted by two or more kinds of convergent yarns made of fibers of different colors, the tear string 1 having two or more colors can be obtained without dyeing or coloring the fibers. .
[0022]
Here, examples of the fibers having inherently unique colors include aromatic polyamide fibers having a color close to yellow. When this yellow aromatic polyamide fiber is used, if it is used in combination with an essentially white synthetic fiber such as a polyester fiber, a tear string of two or more colors can be produced without going through a coloring step.
[0023]
For example, as shown in FIG. 1, the tear string of the present invention includes a buffer material 3 disposed around an optical fiber 4, and a buffer fiber in the resin cover portion 2 in an optical fiber cable 5 covered with the resin cover portion 2. Although embedded in the contact portion with the material 3, it may be embedded in an optical fiber cable of another cable structure.
[0024]
【Example】
EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the examples.
[0025]
Example 1
Polyethylene terephthalate filament yarn 1100 dtex (192 filament) is twisted in the Z direction with a twist factor of 3.5 to form a twisted cord, and then the three twisted cords are combined to twist in the S direction with a twist factor of 4.0 To make a twisted string. Here, a cord from a filament yarn dyed yellow was used for one of the three cords that were twisted, and a cord from a white filament yarn that was not dyed was used for the other two cords.
The obtained tear string was one in which one yellow cord and two produced white cords were twisted together, and the stripe pattern of yellow and white was clearly recognizable.
[0026]
When the tear string was embedded in the optical fiber cable having the structure shown in FIG. 1, it was easy to distinguish it from the fiber (white color) of the buffer material. Further, since the dyed fiber was used for only one of the three cords, the dyeing cost could be reduced as compared with the yellow tear string.
[0027]
Example 2
An aromatic polyamide fiber “Kevlar” (trade name of DuPont) 800 dtex filament yarn (490 filament, strength 20.3 cN / dtex), a single twisted cord obtained by adding a twist in the Z direction with a twist factor of 3.0, Two lower twisted cords obtained by adding a lower twist of a Z direction in a twisting factor of 3.0 to a polyethylene terephthalate filament yarn 1100 dtex (192 filaments) were twisted in the S direction at a twisting factor of 3.5 to obtain a tear string.
[0028]
The resulting tear string is made using fibers of the color that has not undergone the coloring process, but the yellow cords of the aromatic polyamide fibers and the original white cords of the polyester fibers are twisted together. The striped pattern with white was clearly recognizable, and was excellent in discriminability like the tear string of Example 1.
[0029]
Example 3
Aromatic polyamide fiber “Kevlar” (trade name of DuPont) 220 dtex filament yarn (134 filament, strength 20.3 cN / dtex), two cords twisted in the Z direction with a twist coefficient of 1.0, and polyethylene terephthalate filament yarn 245 dtex A braid was made by a usual method from six cords twisted in the Z direction with a twist coefficient of 1.0 on (50 filaments). A cord of a polyethylene terephthalate filament yarn 1100 dtex (192 filament) with a twist coefficient of 1.0 and a Z-direction twist yarn was inserted into the center of the braid so that the braid had a circular cross section, which was used as a tear cord.
[0030]
The obtained tear string uses fibers of a color that has not undergone a coloring process, but a two-color pattern appears on the surface of the string due to the original yellow cord of the aromatic polyamide fiber and the white cord of the polyester fiber. Thus, the tear string was also excellent in distinguishability like the tear string of Example 1.
[0031]
【The invention's effect】
Since the two or more colors appear on the surface of the optical fiber tear string according to the present invention, it is easy to distinguish it from the buffer material in the optical fiber cable, and the position of the tear string can be easily found from the optical fiber cable. be able to. Therefore, by burying the tear string, it is possible to improve the workability of tearing the resin cover when the optical fiber cable is connected.
[0032]
In addition, the tear string of the present invention has a coloring for improving the distinguishability, but can use the original color of the fiber, and can use different fibers in combination. Can also be reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically showing a cross-section of an embodiment of an optical fiber cable in which a tear string is embedded.
[Explanation of symbols]
1 Tear string 2 Resin cover 3 Buffer material 4 Optical fiber 5 Optical fiber cable

Claims (8)

A tear string for an optical fiber cable composed of a plurality of two or more types of bundled yarns of substantially different colors. The tear string for an optical fiber cable according to claim 1, wherein the bundled yarn is a twisted string formed by twisting a plurality of substantially different colors of the twisted yarn. 2. The tear string for an optical fiber cable according to claim 1, wherein the bundled yarn is a yarn twisted and a braid formed by combining a plurality of substantially different colors of the yarn twisted. The tear string for an optical fiber cable according to any one of claims 1 to 3, wherein at least one kind of fibers having substantially different colors is a fiber having inherently unique colors. The tear string for an optical fiber cable according to any one of claims 1 to 4, wherein at least one of the bundled yarns having substantially different colors is a yarn composed of high-strength fibers having a strength of 15 cN / dtex or more. One type of bundled yarns of substantially different colors is a yarn composed of high-strength fibers having a strength of 15 cN / dtex or more, and the other type is one of polyester fibers, polypropylene fibers and polyamide fibers. The tear string for an optical fiber cable according to any one of claims 1 to 4, which is a yarn comprising the above. The tear string for an optical fiber cable according to claim 5 or 6, wherein the high-strength fiber is an aromatic polyamide fiber. An optical fiber cable in which a tear string according to any one of claims 1 to 7 is embedded inside a resin cover part in an optical fiber cable in which the periphery of the optical fiber is covered with a buffer material and a resin cover part.

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