JP2004012811A - Optical fiber ribbon with jacket - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coated optical fiber ribbon with a jacket which protects the coated optical fiber ribbon, permits the easy removal of a coating with a smaller force without damaging the fiber during working of its terminal, makes the flame retardance characteristics better than those of the coated optical fiber ribbon alone, and does not increase a light loss value even at a low temperature. <P>SOLUTION: The coated optical fiber ribbon 1 with the jacket consists of the structure where a flame retardant plastic jacket 5 is put on the outer periphery of a coated optical fiber ribbon 2 by passing the coated optical fiber ribbon through a previously formed tubular coating or extrusion molding the jacket on the outer periphery of the coated optical fiber ribbon. The coated optical fiber ribbon having a jacket stripping force of 100-1,000 gf/200 mm, an oxygen index of the jacket of ≥25 and a thickness of the jacket of 0.2-0.8 mm is provided. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical fiber tape cored in an optical connection box or the like.
[0002]
[Prior art]
In recent years, as the amount of information has increased and the use of optical communication has been accelerated, it has become necessary to use optical fibers in addition to long-distance communication between communication stations, as well as to increase the number of cores used in system wiring within offices and premises. ing. Then, the optical fiber system is laid in a general home. In an optical fiber system having a short transmission distance, connection technology and connection work are important matters.
FIG. 3 is a cross-sectional view of a conventional optical fiber ribbon. In FIG. 3, reference numeral 3 denotes an optical fiber, which is obtained by coating an optical fiber comprising a core and a clad with a primary coating such as an ultraviolet curable resin or further with a secondary coating. The optical fiber ribbon 2 is formed by arranging the optical fiber strands 3 in one plane, and collectively forming a common coating 4 made of an ultraviolet curable resin or the like on the outer periphery thereof (this coating is composed of two layers of an inner layer and an outer layer). And may be used for multi-core cables because they can be mounted with high density.
Further, as an optical fiber ribbon, there is also known an optical fiber ribbon with a jacket in which the outside is further covered with an ultraviolet curable resin or the like after the above-mentioned batch coating in order to improve the lateral pressure characteristics and the like.
In general, a method in which an optical fiber ribbon without such a jacket is directly wired even in an optical connection box or a transmission device having a short transmission distance is used. In the method of wiring the optical fiber ribbon as it is, during the wiring work, the tape ribbon is hooked on a sharp part such as a protrusion or a burr in the connection box, or a strong impact is given to the optical fiber ribbon. In many cases, the optical fiber ribbon is damaged, and the wiring work requires time and skill. In addition, in order to wire a cable with a jacket, it is necessary to strip the jacket layer at the end of the optical fiber ribbon.
[0003]
[Problems to be solved by the invention]
In the wiring work, a large force is required to peel off the coating at the end of the optical fiber ribbon having such a jacket, and the force is 1500 gf / 200 mm or more. Since the wire has a high grip force, it is difficult to take it out in a tape core state, so that the tape core without covering is used as it is.
In addition, UV-curable resin is generally used for coating the optical fiber ribbon, but since UV-curable resin is a very flammable material, a fire may occur and When the fiber ribbon is ignited, there is a danger that the optical fiber ribbon plays a role as a squib and the fire is spread.
Therefore, the present invention protects the optical fiber ribbon, easily removes the coating with a small force without damaging the fiber when processing the end portion, and further improves the flame retardancy characteristics compared to the optical fiber ribbon alone. It is another object of the present invention to provide a sheathed optical fiber tape in which the optical loss value does not increase even at a low temperature.
[0004]
[Means for Solving the Problems]
The present inventors have studied the structure of an optical fiber core wire in view of the above problem, and as a result, have found that it is better to have a jacket having a specific peeling force. Therefore, the present invention has been made based on these findings.
That is, the present invention
(1) An optical fiber tape core wire is passed through a previously formed tubular coating or extruded around the optical fiber tape core wire to form an outer periphery of the optical fiber tape core with a flame-retardant plastic. An optical fiber tape with a jacket, wherein the jacket is formed and the sheath peeling force is 100 gf / 200 mm or more and 1000 gf / 200 mm or less;
(2) The optical fiber tape with a jacket according to (1), wherein the flame retardant plastic jacket has an oxygen index of 25 or more.
(3) The thickness of the flame-retardant plastic jacket is 0.2 mm or more, and the optical fiber ribbon with the jacket according to (1) or (2), and
(4) The optical fiber tape with the jacket according to (1), (2) or (3), wherein the thickness of the flame-retardant plastic jacket is 0.8 mm or less.
Is provided.
[0005]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the optical fiber ribbon with a jacket according to the present invention will be described in more detail with reference to the drawings.
FIG. 1 is a cross-sectional view showing the structure of an optical fiber ribbon with a jacket according to one embodiment of the present invention.
In this embodiment, a twelve-core optical fiber tape with a sheath is shown, but the number of optical fiber strands is not limited to twelve, and any number of optical fiber strands can be appropriately set as needed. Are arranged in parallel in one plane, and they are coated in two layers (an inner layer 4a and an outer layer 4b) with an ultraviolet-curable resin to form an optical fiber tape core. Line 2 is formed. Of course, the common coating 4 of the ultraviolet curable resin may be a single layer. Then, an outer jacket 5 is further covered on the outer periphery to form an optical fiber tape cored cable 1 with an outer jacket.
[0006]
In the method of the present invention, in which the outer jacket 5 is formed by passing a core wire of an optical fiber tape, which is a conventionally known coating means, through a die section and extruding a coating resin into the die section under pressure, Since it is difficult to control the adhesion of the outer cover, it is difficult to reduce the peeling force of the jacket. Therefore, in the present invention, the jacket 5 having a desired sheath peeling force can be covered by controlling the adhesion between the two by the pipe extrusion molding means.
In the pipe extrusion method of the present invention, the "tightening force" and "grip force" of the resin applied to the optical fiber ribbon are changed by changing the setting of the nipple and the die, so that the peeling force of the jacket 5 can be reduced to 100 gf / 200 mm to 1000 gf /. It can be 200 mm.
[0007]
As a means for coating the jacket 5 of the present invention, a method of inserting the optical fiber ribbon 2 into a tubular coating prepared in advance is preferable. In this method, a tube that contracts by applying heat is selected, the optical fiber ribbon 2 is passed through a tube having an inner diameter larger than the outer diameter of the optical fiber ribbon, and then the tube is contracted by applying heat. It is a processed product. The adhesive force can be controlled by the difference between the outer diameter of the optical fiber ribbon and the inner diameter of the tube, the heating rate and the heating temperature.
For example, the difference between the outer diameter of the long side of the tape core wire and the inner diameter of the tube is 0.2 to 0.4 mm, the heat shrinkage is about 50%, and a tube having a predetermined thickness is used. By holding for a minute, the peeling force of the jacket 5 can be made 100 gf / 200 mm to 1000 gf / 200 mm.
[0008]
By this control, the peeling force of the jacket covering the optical fiber ribbon is set to 100 gf / 200 mm or more and 1000 gf / 200 mm or less. If the peeling force is less than 100 gf / 200 mm, only the jacket is displaced during handling, and the tape core is exposed at the terminal portion, so that a peeling force of 100 gf / 200 mm or more is required. On the other hand, if the value is too large, it is difficult to take out the tape in the state of the cord as described above, and the workability of the cord terminal becomes extremely poor. Preferably it is 300 gf / 200 mm to 800 gf / 200 mm, more preferably 500 gf / 200 mm to 700 gf / 200 mm.
As described above, the peeling force of the outer cover is lower than that of the conventional one and is in an appropriate range. Therefore, by using a general tool such as a cutter, it is possible to easily peel off only the flame-retardant plastic outer cover. It does not cause an increase in optical loss of the fiber.
[0009]
The sheath peeling force shown above was measured as follows. As shown in FIG. 2, the outer and outer ends of the tape core wire 1 having a length of 350 mm are shaved, and one end (left) is peeled off by 50 mm and the other end (right) is peeled off by 100 mm with a sharp blade such as a blade. And leave a 250 mm jacket 5 in the middle. After that, the remaining sheath portion was fixed, the core portion peeled off by 100 mm was fixed to the tensile tester 6, and the force required to pull out the tape core portion from the jacket portion was measured. The peeling force was used.
[0010]
In the flame-retardant plastic sheath material of the present invention, since the common coating material of the tape core wire is an ultraviolet-curing material, it is clear that even if the coating is performed with the ultraviolet-curing material, it will be in close contact. The flame-retardant plastic material is preferably a polyvinyl chloride resin or a flame-retardant polyolefin resin, but is not limited thereto, and a polyamide resin or the like can be used.
Such a flame-retardant plastic jacket material can be used by imparting flame retardancy to the above-mentioned ones. As a method of making the coating flame-retardant, flame retardancy can also be imparted when synthesizing the resin.Addition of a flame retardant before curing, for example, also to a material that is not imparted with flame retardancy, is also possible. You can do it too.
As the flame retardant, for example, known ones such as a halogen-containing phosphoric ester, a non-halogen phosphoric ester, or a reactive halogen-based flame retardant can be used.
As the material of the jacket, a flame-retardant plastic material having an oxygen index of 25 or more, preferably 27 or more, is used in consideration of the flame retardancy. Since the physical properties deteriorate, the upper limit of the oxygen index is about 40. The oxygen index shown here was determined according to JIS K7201 “Method for Combustion Test of Polymer Material by Oxygen Index Method”.
[0011]
According to the result of an experiment in which a UL1581VW-1 burning test, which is a general burning test of an optical fiber cable, was performed using a sheathed optical fiber tape using a flame-retardant plastic material having an oxygen index of 25, It was found that sufficient flame-retardant properties were obtained when the thickness was 0.2 mm or more. Of course, it is easily presumed that the thickness of the jacket can be further reduced by using a material having a higher oxygen index.
It is also known that the flame-retardant plastic material used as the jacket shrinks at low temperatures. It is well known that a large amount of shrinkage of the coating material causes a bending stress to be applied to the optical fiber ribbon, which may increase the optical loss value of the optical fiber ribbon. Since the amount of shrinkage is generally proportional to the cross-sectional area of the coating, the thinner the jacket, the better. Depending on the number of cores of the optical fiber and the coefficient of linear expansion of the plastic material, if the thickness is 0.8 mm or less, the optical fiber ribbon will not be bent.
[0012]
【Example】
Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
Eight optical fiber strands 3 having a diameter of 250 μm coated with a UV-curable resin are arranged in parallel in a plane as shown in FIG. 1 and are collectively covered with a urethane acrylate UV-curable resin. An eight-core ribbon 2 having an outer diameter of 0.4 mm × 2.1 mm was obtained.
The 8-core tape is inserted into a tube made of an electron beam crosslinked soft flame-retardant polyolefin having an inner diameter of 2.4 mm and an outer diameter of 2.7 mm and an oxygen index of 35, and kept at 100 ° C. for 3 minutes. Thus, a sheathed optical fiber tape was obtained. The stripping force of the obtained coated optical fiber tape was 500 gf / 200 mm on average.
[0013]
【The invention's effect】
When the optical fiber ribbon with the sheath of the present invention is used, the sheath can be easily peeled off using a general tool, and a connector or the like can be attached to the end of the optical fiber ribbon. When using the sheathed optical fiber tape of the present invention for the wiring of an optical wiring box or the like, compared with the conventional work of wiring the optical fiber tape, the optical fiber tape for protection from external damage is provided. Since the outer periphery of the wire is covered, the handling of the optical fiber becomes easy.
Further, since the flame-retardant plastic is used as the material of the jacket, the flame-retardant properties can be improved and the optical loss of the optical fiber can be prevented from increasing even at a low temperature.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of an optical fiber tape cored cable according to the present invention.
FIGS. 2A and 2B are simplified explanatory views showing a method for measuring a peeling force, in which FIG.
FIG. 3 is a cross-sectional view of a conventional optical fiber ribbon.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Optical fiber tape core with a sheath 2 Optical fiber tape core 3 Optical fiber 4 Common coating 5 Jacket 6 Tensile tester

Claims (4)

A flame-retardant plastic jacket is formed on the outer circumference of the optical fiber ribbon by passing the optical fiber ribbon through the preformed tubular coating or extruding the outer circumference of the optical fiber ribbon. And a sheath stripping force of 100 gf / 200 mm or more and 1000 gf / 200 mm or less. The optical fiber ribbon with a jacket according to claim 1, wherein the flame retardant plastic jacket has an oxygen index of 25 or more. The optical fiber ribbon with a jacket according to claim 1 or 2, wherein the thickness of the flame-retardant plastic jacket is 0.2 mm or more. 4. The optical fiber ribbon with a jacket according to claim 1, wherein the thickness of the flame-retardant plastic jacket is 0.8 mm or less. 5.

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