JP2011033743A - Optical cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical cable that allows a cover layer for covering a tension member to be easily identified even when the tension member made of a steel wire is exposed from an outer cover. <P>SOLUTION: The optical cable is configured by arranging tension members 3 made of steel wires on both sides of a coated optical fiber 2, to be covered with outer covers 4. The outer circumference of the tension member 3 is covered with a cover layer 8 containing white pigment. Preferably, the cover layer 8 uses modified polyolefin as a base resin, and the white pigment is titanium white. Preferably, a thickness H of the cover layer 8 that covers the tension member 8 is 0.05 to 0.2 mm. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical cable which is an indoor optical cable suitable for being installed by being inserted into an existing pipe line, and tension members are arranged on both sides of an optical fiber core and covered with a jacket.

  With the full-scale introduction of FTTH (Fiber To The Home) in recent years, there is an increasing demand for optical cable wiring to each house even in apartment houses such as existing condominiums. In existing condominiums and the like, there are few places for installing optical fiber laying pipes, and a method of laying optical cables using pipes containing existing telephone lines has been considered. An optical cable installed in a building is usually also called an indoor optical cable, and a tension member (also called a tensile body) such as a steel wire is arranged on both sides of an optical fiber core or an optical fiber ribbon, and a sheath (sheath) In other words, it is used in a configuration in which it is covered all at once.

  For example, as disclosed in Patent Document 1, a fatty acid-based lubricant is included in the outer sheath of an optical cable to reduce the dynamic friction coefficient of the outer sheath surface, as disclosed in Patent Document 1, for example. There is. Further, in Patent Document 2, an adhesive is provided between the tensile body and the outer cover in order to prevent the optical cable from being bent and ironed during laying and the outer cover from expanding and contracting due to the heat cycle after laying. It is disclosed to increase the adhesive force between the strength member and the jacket by interposing.

JP 2007-183477 A JP 2000-171673 A

  When an optical cable is laid using a telephone line, it is necessary to pass a plurality of optical cables in addition to the existing telephone line, and it cannot be said that there is sufficient space. When an optical cable is inserted into such a narrow pipe line, there is a risk of damaging an existing cable or the like if it is inserted using a wiring tool. Therefore, although it is desired to insert the optical cable alone into the pipe without using a wiring tool, the insertion is not easy only by using a thin optical cable (for example, 2 mm thick × 3 mm wide).

  As disclosed in Patent Document 1, it is possible to improve a certain degree of penetrability by using a method of making the outer surface of the optical cable slip by making the outer surface of the optical cable contain a lubricant. However, the lubricant added to the jacket of the optical cable is likely to bleed, and the lubricant may penetrate between the optical fiber and the fiber coating. When the outer cover lubricant penetrates into the inner surface of the fiber coating, it causes an increase in transmission loss of the optical fiber. Further, when a lubricant is included in the jacket of the optical cable, it becomes easy to slip between the optical fiber core wire and the tension member. For this reason, there is a problem that the outer sheath expands or contracts due to bending, ironing, heat cycle, or the like of the optical cable, and the optical fiber tends to protrude or retract.

  Therefore, in order to improve the lineability of the optical cable into the pipeline, it is conceivable to reduce the outer dimension of the outer cover of the optical cable to near the limit. However, even if a steel wire having a higher tensile strength than other materials is used as the tension member disposed in the outer jacket, the current thickness (0.4 mm to 0 mm) is required to ensure the necessary allowable tension. It is difficult to make it thinner than 0.5 mm). For this reason, when the outer dimension of the jacket of the optical cable is reduced, the coating on the steel wire as the tension member becomes thin.

  When the outer jacket of the optical cable becomes thinner, the resistance to tool dropping or the like that occurs during the wiring operation of the optical cable decreases. As a result, when an impact is applied to the optical cable, the outer cover on the steel wire, which is the tension member, is peeled off or cracked, and the steel wire is exposed and rust is likely to occur. For this reason, when such an accident occurs, the replacement of the optical cable and the laying work are performed again.

  However, as disclosed in Patent Document 2, when an adhesive layer is provided on the outer periphery of the tension member in order to increase the adhesive strength with the outer cover, the outer cover may be peeled off when the optical cable receives an impact or the like. However, the adhesive on the steel wire inside may remain, and the steel wire may not be exposed to the outside. In such a case, it is possible to avoid re-working the construction of the optical cable. However, the steel wire used for the tension member of the optical cable usually has a blackish color, the optical cable drawn into the house is a white light color, and the adhesive layer is a transparent color such as Admer.

For this reason, although the outer cover is cracked, even if the steel wire is covered with the adhesive layer and is not exposed, it is erroneously determined that it is exposed, and extra work may be forced.
The present invention has been made in view of the above-described circumstances, and it is easy to determine whether or not there is a coating layer covering the tension member even when the tension member made of steel wire is exposed from the outer jacket. The purpose is to provide an optical cable that can be used in a simple manner.

An optical cable according to the present invention is an optical cable in which a tension member made of a steel wire is arranged on both sides of an optical fiber core and is covered with a jacket, and the outer periphery of the tension member is covered with a coating layer containing a white pigment. It is characterized by being.
The coating layer is preferably a modified polyolefin as a base resin, and the white pigment is preferably titanium white. Also, the thickness of the coating layer covering the tension member is preferably 0.05 mm to 0.2 mm.

  According to the optical cable of the present invention, whether or not the tension member is covered with the covering layer even when an impact is applied to the optical cable and the outer cover is peeled off and the tension member made of an internal steel wire is exposed. Can be easily confirmed. And when it is covered with a coating layer, it is possible to dispense with repair work.

It is a figure explaining the outline of embodiment of the optical cable by this invention. It is a figure which shows the evaluation result of the optical cable by this invention.

  An embodiment of the present invention will be described with reference to FIG. FIG. 1A is a diagram showing a cross section of an optical cable according to the present invention, and FIG. 1B is a diagram showing a state in which the optical cable is inserted into an existing telephone line. In the figure, 1 is an optical cable, 2 is an optical fiber core, 3 is a tension member, 4 is a jacket, 5 is a notch, 6 is a telephone line, 7 is a telephone line, and 8 is a coating layer.

  An optical cable 1 according to the present invention has, for example, a generally known rectangular cross section as shown in FIG. 1 (A), and a pair of tension members 3 are arranged in parallel on both sides of an optical fiber core 2. The outer cover 4 is integrally covered and, for example, notches 5 are provided on both side surfaces of the outer cover 4. As shown in FIG. 1B, for example, 20 or more optical cables 1 are required to pass through an existing pipe line 6 (with an inner diameter of about 22 mmΦ) into which a telephone line 7 is already inserted. ing. Moreover, this pipe line 6 is intended for an optical cable that usually has about five bends and can be routed by pushing the optical cable alone without using a wire rod or the like.

  The optical fiber core wire 2 in the optical cable has, for example, a standard glass bare fiber diameter of 125 μm and a fiber coating outer diameter of around 250 μm, and is arranged in one or two cores. The tension member 3 is provided with a single core steel wire having an outer diameter of 0.4 mm to 0.5 mm and sandwiching the optical fiber core 2 from both sides. The outer cover 4 has a rectangular cross section and is made as thin as possible. The short side (thickness T) is 2.0 mm or less and the long side (width D) is 3.0 mm or less. It is preferable to increase the number of pushing into the pipe 6. Further, when forming the end of the optical cable, notches 5 for easily tearing the outer cover 4 in the longitudinal direction and taking out the inner optical fiber 2 can be provided on both side surfaces of the outer cover 4. it can.

  The jacket 4 of the optical cable 1 is formed of a polyethylene resin, and high density polyethylene (HDPE) is particularly preferable. By using high-density polyethylene for the jacket 4, the density of the jacket 4 is higher and harder than those of low-density polyethylene (LDPE), linear low-density polyethylene (L-LDPE), and medium-density polyethylene (MDPE). Therefore, the lineability into the pipeline 6 can be enhanced.

  In the present invention, the outer periphery of the tension member 3 made of a steel wire is covered with the coating layer 8 containing a white pigment, in particular, with the optical cable having the above configuration. The covering layer 8 is preferably formed by extrusion molding with an adhesive resin, thereby improving the adhesion between the tension member 3 and the outer cover 4, suppressing expansion / contraction and meandering of the outer cover 4, and Loss increase and disconnection can be reduced. The resin material for the coating layer 8 is preferably a modified polyolefin as a base resin. Modified polyolefin has good extrudability to tension members, can improve adhesion by introducing functional groups into polyolefins such as polyethylene and polypropylene, has excellent impact resistance, and balances between these properties and cost Also good.

  Examples of the white pigment to be contained in the coating layer 8 include titanium white (titanium dioxide), zinc oxide, lithopone (a mixture of zinc sulfide and barium sulfate), zinc sulfide, and the like. In particular, titanium white is preferable. This titanium white (titanium dioxide) is known to have higher coloring power and higher hiding power than other white pigments, and is easily noticeable when exposed from the outer cover, making it difficult to see the tension member. The white pigment may be combined with other pigments to form a light gray or light color.

  The coating layer 8 is preferably formed with a thickness H in the range of 0.05 mm to 0.02 mm. As the thickness H of the covering layer 8 increases, the adhesion to the tension member 3 and the outer cover 4 increases. However, if the thickness H is too thick, the coating layer 8 is soft and thus has a reduced impact resistance. For this reason, it is desirable to form the tension member 3 on the entire outer periphery in the above-described range.

  As described above, by interposing the white and opaque coating layer 8 between the tension member 3 and the outer jacket 4, the outer shell 4 is cracked by an impact or the like, and the tension member 3 made of a steel wire inside. However, if the steel wire is covered with the covering layer 8, there is no problem, and it is possible to avoid extra repair work. Whether or not the steel wire is covered with the coating layer 8 can be easily identified by adding a white pigment different from the color of the steel wire of the tension member and the color of the jacket 4 to the coating layer 8. Misjudgments regarding line exposure can be reduced.

FIG. 2 is a diagram showing the results of the impact test of the optical cable described above. In the test, a 300 g weight was dropped from 1 m above the optical cable, and the exposed state of the tension member (steel wire) was observed.
Sample No. 1 is a conventional optical cable without a tension member covering layer, Sample No. 2 is a conventional optical cable with no white pigment added to the tension member covering layer, and Sample No. 3 is a tension member covering. An optical cable in which 3 parts by weight of a white pigment (color batch in which titanium white is blended) is blended in the layer, and sample No. 4 is an optical cable in which 10 parts by weight of the white pigment (same) is blended in the covering layer of the tension member.

  As the optical fiber core wire 2 of the optical cable used for the test, a glass fiber having a standard outer diameter of 125 μm and a fiber coating having an outer diameter of 250 μm was used. A steel wire having a thickness of 0.5 mmΦ was used for the tension member 3, a modified polyethylene was used for the coating layer 8, and the coating thickness H was set to 0.1 mm. The outer cover 4 was formed by extrusion molding with high-density polyethylene (HDPE) as a base resin, with a thickness T of 1.6 mm and a width D of 2.0 mm.

  In the optical cable of Sample No. 1, the steel wire was exposed from the cracked portion of the jacket, and the black steel wire could be confirmed. In the optical cable of sample No. 2, the steel wire was not exposed because it was covered with the coating layer from the cracked portion of the jacket. It was determined. In the optical cable of sample No. 3 and the optical cable of sample No. 4, the steel wire is not covered and exposed from the crack portion of the jacket, and the steel wire is not exposed by identifying the coating layer. Therefore, it was judged as good.

  From the above results, it is easy to determine whether or not the steel wire is exposed even if the outer cover is cracked by impact or the like by covering the tension member made of steel wire with a coating layer containing white pigment. can do. As a result, when the steel wire is covered with the coating layer, the steel wire is not rusted, so that the trouble of replacing or repairing the optical cable can be saved. In addition, this makes it possible to reduce the outer dimension of the jacket to the limit, facilitate communication within the pipeline, and improve lineability.

DESCRIPTION OF SYMBOLS 1 ... Optical cable, 2 ... Optical fiber core wire, 3 ... Tension member, 4 ... Outer sheath, 5 ... Notch, 6 ... Telephone line, 7 ... Telephone line, 8 ... Covering layer.

Claims (4)

  An optical cable in which a tension member made of a steel wire is arranged on both sides of an optical fiber core and is covered with a jacket, characterized in that the outer periphery of the tension member is covered with a coating layer containing a white pigment. Optical cable.   The optical cable according to claim 1, wherein the coating layer uses a modified polyolefin as a base resin.   The optical cable according to claim 1, wherein the white pigment is titanium white.   The thickness of the said coating layer is 0.05 mm-0.2 mm, The optical cable of any one of Claims 1-3 characterized by the above-mentioned.

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