JPH07225331A - Waterproof tape - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a waterproof tape having a small linear expansion coefficient and capable of preventing reduction in transmission loss of an optical cable using the same at low temperatures. [Structure] FIG. 1A is a plan view of the waterproof tape, FIG.
(B) is a sectional view thereof. The waterproof tape is a water-absorbing material 1 integrated with a glass fiber 2 by a water-soluble binder 3. By including long glass fibers in the waterproof tape, the coefficient of linear expansion of the waterproof tape can be made smaller than 1 × 10 to the power of −5, and this waterproof tape can be used as a tape core wire in an optical cable using the tape core wire. By storing the optical cables so that they come into contact with each other, it is possible to suppress an increase in loss of the optical cable at low temperatures.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waterproof tape used for optical cables.

[0002]

2. Description of the Related Art As a means for imparting waterproof properties to an optical cable, generally, a gel-like filler called a waterproof mixture is injected into the cable to prevent water from entering from the outside. A method in which a water-absorbing material that absorbs / holds water is processed directly or in the form of a tape, and the water-absorbing material absorbs and expands when it is flooded to prevent water from flowing into the deep part of the cable. There are two main methods.

The present invention relates to a method of
The method of (3) is a method of directly attaching the water absorbing material to the cable core by, for example, electrostatic coating. The water-absorbent fibers are directly processed into a cloth, or the cloth is processed by applying or impregnating a water-absorbing material into a cloth, and then processed into a tape, which is then used as a press-winding tape. A method of wrapping around a core (a method of using a water-absorbing tape that is pressed down). In a cable having a structure in which a transmission medium (for example, an optical fiber) is housed in a groove / tube, the narrow water-absorbing tape whose width is the cloth-like water-absorbing tape is made to contact the transmission medium in the groove / tube. How to enclose together. are categorized.

The waterproof tape of the present invention is applied to the method of, but as a report of an example in which the method of the prior art is actually applied, for example, "A non-metal waterproof optical fiber cable made of a water absorbing material is used. Design and Features ”(Kukida et al., OQE87-6, pp.39-46).

At that time, the optical cable used the GI type optical fiber in the transmission region of 0.85 μm band, but due to technological innovation, S used in 1.31 μm band.
When M-type optical fibers were manufactured at a lower cost than GI-type optical fibers, the mainstream of optical cables shifted from GI-type optical fiber cables to SM-type optical fiber cables. Also for waterproof tape, the method of using narrow water-absorbing tape so that it contacts the transmission medium in the space inside the groove or tube is shunned because the slit machining cost increases,
It started to shift to holding roll water absorbent tape.

On the other hand, regarding the optical cable, since the main purpose has been conventionally the relay connection between telephone stations,
As for the number of optical fiber cores in the cable, it is sufficient to have several hundred optical fibers, and up to 300 optical fibers are currently used for relaying in Japan, and the outer diameter of the cable is
It is less than 25 mm at most.

However, if optical fibers are to be applied to all telephone subscribers in the future, there will be a one-to-one correspondence between stations and subscribers.
Since it is necessary to connect the lines with, it is expected that thousands of optical fibers will be required. Such an optical cable having a large number of fibers is expected to have an outer diameter of, for example, 40 mm or more, and a device for reducing the outer diameter of the cable as much as possible is required.

In the case of a cable using waterproof tape, for example, in the case of adopting a structure in which optical units are gathered and twisted together, the outer diameter of the narrow water absorbing tape is smaller than that of the holding water absorbing tape. There are cases where it is advantageous to

When the currently used waterproof tape is made into a thin slit shape and is housed in an optical cable, the waterproof tape is condensed at a low temperature and is in contact with it in a low temperature region (-30 ° C.) that is assumed in actual use. There is a possibility that the optical fiber may be bent to deteriorate the transmission characteristics. For this reason, it is necessary to develop a waterproof tape having a small coefficient of linear expansion in order to prevent a reduction in transmission loss of the optical fiber at low temperatures.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and realizes a waterproof tape having a small linear expansion coefficient, and prevents a decrease in transmission loss of an optical cable using the same at low temperatures. The purpose of the present invention is to provide a waterproof tape that can be used.

[0011]

According to a first aspect of the present invention, there is provided an optical cable in which optical fiber cores are arranged in parallel and coated together to form an optical cable in which the tape cores are provided. In the waterproof tape that is housed in contact with the waterproof tape, the waterproof tape includes a water absorbent material and glass fiber that is long in the longitudinal direction thereof, so that the coefficient of linear expansion of the waterproof tape is 1 ×.
It is characterized in that it is smaller than 10 to the 5th power.

According to a second aspect of the invention, in the first aspect of the invention, the glass fiber and the water absorbing material are integrated by a binder, and the binder has a softening point of 60 ° C. or higher and 100 ° C. or lower. It is a water-soluble extruded material having

According to a third aspect of the present invention, in the first or second aspect of the present invention, the glass fiber is an optical fiber.
In the invention described in claim 3, in the invention described in claim 3, the optical fiber is used as an intervening wire for communication.

[0014]

In general, the coefficient of linear expansion of cloth (plastic tape such as non-woven fabric, stretched tape such as polyester) forming the waterproof tape is about 10 −4, which is the linear expansion coefficient of glass forming the optical fiber. It is far away from a certain 10 minus 7. In general, aramid fiber, which is said to have a large elastic coefficient, does not work well when it is shrunk at low temperatures, and the linear expansion coefficient cannot be expected to improve even if it is included in a waterproof tape. Therefore, as the filler, glass fiber arranged along the longitudinal direction of the waterproof tape is desirable.

According to the first aspect of the present invention, by inserting the glass fiber into the waterproof tape, the coefficient of linear expansion of the waterproof tape can be made smaller than 1 × 10 −5.
The coefficient of linear expansion can be suppressed to a level at which there is no practical problem.

According to the second aspect of the present invention, the glass fiber and the water absorbing material are integrated by a binder, and the binder is a water-soluble extrusion material having a softening point of 60 ° C. or higher and 100 ° C. or lower. As a result, the water absorbing properties of the water absorbing material are not impaired during extrusion. Further, when the glass fibers are resin-coated, the resin coating is not affected at a temperature of 100 ° C. or lower.

Further, the linear expansion coefficient of the glass constituting the optical fiber is approximately 10 −7, and the linear expansion coefficient is sufficiently small. According to the invention of claim 3, by using the optical fiber as the glass fiber, the coefficient of linear expansion of the waterproof tape can be suppressed to be lower and the utilization efficiency as a communication medium can be improved. .

According to the invention described in claim 4, not only can the utilization efficiency as a communication medium be improved, but
Since the optical fiber can also be used as an intervening wire for communication, its utilization efficiency can be further enhanced.

[0019]

EXAMPLE FIG. 3 is an explanatory view of a state in which the waterproof tape is inserted in contact with the tape core wire. In the figure, 11 is a groove portion, 1
Reference numeral 2 is a tape core wire, and 13 is a waterproof tape.

FIG. 3A shows the case without a waterproof tape. In this example, five tape core wires 12 are inserted into the grooves 11 formed in the spacer member or the like.

FIG. 3B shows the case where the waterproof tape is inserted into the groove. The waterproof tape 13 is stacked on the five stacked tape core wires 12. The waterproof tape 13 may be put on the groove bottom of the groove 11. Of course, it can be arranged both on the groove and on the groove bottom.

FIG. 3C shows the case where the waterproof tape is inserted while being sandwiched between the tape core wires. It can be inserted anywhere. May be inserted in multiple positions, or in addition,
As described in FIG. 3B, the positions on the groove and the groove bottom may be combined.

Although the waterproof tape 13 is shown as one sheet in FIGS. 3B and 3C, it may be a combination of a plurality of sheets. Further, FIG. 3 shows an example in which the tape core wire 12 is inserted into the rectangular groove 11, but the tape core wire may be inserted into a circular space such as a tube.

When the tape cores are confined in the closed space as described above, the tape cores expand and contract due to temperature change, but when the tape cores are in contact with each other as shown in FIG. 3A, linear expansion occurs. Since the coefficients are the same, there is no problem as the length changes without a balance.

However, when the inclusions having different linear expansion coefficients are brought into contact with the tape core wire and accommodated therein, imbalance occurs and local bending occurs in the optical fiber, resulting in increased loss. It is difficult to completely match the linear expansion coefficient of different kinds of inclusions having different constituent materials with the core wire of the tape, but it is possible to bring them to a level where there is no practical problem.

The linear expansion coefficient of ordinary plastics is generally larger than 10 to the minus 4th power, with some exceptions, and is remarkably higher than that of the glass constituting an optical fiber to the 10th to the 7th power. It's a big one. Practically, the optical cable is required to satisfy the characteristics in the temperature range of -30 ° C to 60 ° C. Room temperature (20 ℃)
Considering the temperature difference between the temperature and the temperature, the characteristic in the temperature range of 50 ° C., which is the difference from −30 ° C. on the low temperature side, becomes a problem.

In order to satisfy the satisfactory cable characteristics in this temperature range, it is necessary to change the difference in line length when the temperature changes from room temperature to low temperature to 0.05% or less, which will be described later. The coefficient of linear expansion of the waterproof tape
This is equivalent to setting 1 × 10 to the power of −5 or less.

FIG. 1 is for explaining one embodiment of the waterproof tape of the present invention. FIG. 1 (A) is a plan view and FIG.
(B) is a sectional view. In the figure, 1 is a water absorbing material, 2 is glass fiber, and 3 is a water-soluble binder. In this example,
A water absorbent material 1 is integrated with a glass fiber 2 by a water-soluble binder 3. The glass fibers 2 are arranged one on each side in the longitudinal direction. The number of glass fibers on both sides is not limited to one, and a plurality of glass fibers may be arranged. When one glass fiber is used on each side, it is preferable that the entire length of the waterproof tape is seamless. Although they may be connected midway, in that case, they may be fused, or they may be arranged in parallel at an appropriate length over the connecting portion.
When the number of glass fibers is large, it is not necessary to consider the connection unless the connection points are the same.

In the concrete example of this embodiment, as the glass fiber, an S-cured resin having a diameter of 250 μm was coated with an ultraviolet curable resin.
An M type optical fiber was used. As the water-absorbing material, polyethylene oxide (PEO) is dissolved in an organic solvent (toluene, etc.), stirred to make it uniform, and the organic solvent is vaporized and blown off. Was used. Of course, a water absorbing material other than PEO can be used. As the water-soluble binder, one that can be extruded at a temperature of 100 ° C. or lower, for example, polyvinyl alcohol can be used. 10
The reason why the extrusion is performed at a temperature of 0 ° C. or less is to prevent the water absorbing property of the water absorbing material from being impaired, but also to prevent the heat deterioration of the coating material when the optical fiber is used as the glass fiber. For example, in the case of a nylon-coated optical fiber core, even if the extrusion temperature of nylon varies depending on the product type, it is generally 150 ° C to 230 ° C, and a water-soluble binder having a sufficiently lower softening point is required. However, even in the case of an optical fiber using an ultraviolet curable resin,
Since exposure to temperatures above 100 ° C is not preferred, the softening point of the water-soluble binder must be 100 ° C or lower. Further, a material having a low softening point causes a problem if it is softened at ambient temperature. Therefore, the softening point also needs to be 60 ° C. or higher.

In the trial production, a waterproof tape having a linear expansion coefficient as shown by ● in FIG. 4 was produced while changing the number of the UV-curable resin-coated SM optical fibers and the discharge amount of the extrusion material. The linear expansion coefficient was measured by actually exposing the bundled samples to normal temperature (20 ° C.) to low temperature (−30 ° C.) and measuring the change of the optical fiber length in the waterproof tape by the phase method.

This sample was inserted into a one-groove slot formed by cutting a spiral groove on a plastic rod together with a tape core wire, and further twisted around a polyethylene-coated tensile strength member on a steel stranded wire. FIG. 4 shows the result of measuring the loss change (wavelength: 1.55 μm) of the tape core wire at a low temperature in the cable.

As can be seen from FIG. 4, when a waterproof tape having a linear expansion coefficient smaller than 1 × 10 minus 5 is used, the loss increases little when exposed to low temperature, and the waterproof tape Coefficient of linear expansion is minus 1 × 10
The loss increases as it becomes larger than the power. From this, by inserting glass fiber in the waterproof tape and setting the linear expansion coefficient to be less than or equal to 1 × 10 −5, stable characteristics can be obtained even at long wavelengths even if the waterproof tape is inserted together with the tape core wire. Can be maintained.

When an optical fiber is used as the glass fiber contained in the waterproof tape and is made seamless over the entire length of the optical cable, it can be used for communication. It is effective to use it as an intermediary for communication during construction and maintenance.

FIG. 2 is for explaining another embodiment of the waterproof tape of the present invention. FIG. 2 (A) is a plan view and FIG.
(B) is a sectional view. In the figure, the same parts as those in FIG. In this embodiment, the glass tape 2 is included throughout the waterproof tape, and the waterproof tape is integrated with the water absorbent material 2 by the water-soluble binder 3. When extruding the water-soluble binder, glass fiber 2
Is preferably oriented in the longitudinal direction. Also in this embodiment, the coefficient of linear expansion of the waterproof tape can be made smaller than 1.times.10.sup.-5. An optical fiber can also be used as the glass fiber.

Here, the optical fiber will be described. Originally, the optical fiber is a specific wavelength which is the purpose for communication,
For example, an SM optical fiber is usually designed to be used at 1.31 μm, but it is expected that it will be used in a region where the wavelength is changed for maintenance / low-speed communication. For example, the SM type optical fiber has 1.55 μm, 1.
The 65 μm band is the candidate. However, 1.55
In the long wavelength region such as μm and 1.65 μm, the increase in loss due to bending of the optical fiber increases, so that more cautious cabling is desired.

As described above, in an optical cable which is expected to be used in a wide wavelength band in the future, it is necessary to sufficiently consider the inclusions to be put together with the optical fiber. It is also effective for realizing a cable.

[0037]

As is apparent from the above description, according to the present invention, a waterproof tape having a small linear expansion coefficient can be realized by including the glass fiber in the waterproof tape, and an optical cable using the same. It is possible to prevent a decrease in transmission loss at low temperatures. In addition, a binder that integrates the glass fiber and the water-absorbing material is used at a temperature of 60 ° C. or higher and 100
By using a water-soluble extruded material having a softening point of ℃ or less, the water absorbing property of the water absorbing material is not impaired, and the resin coating of the glass fiber is not affected.

Further, by using the optical fiber as the glass fiber, the coefficient of linear expansion of the waterproof tape can be suppressed to a lower level, and when the optical fiber is arranged seamlessly, it is used as an intervening wire for communication. There is an effect that can be done.

[Brief description of drawings]

1A and 1B are views for explaining an embodiment of a waterproof tape of the present invention, FIG. 1A being a plan view and FIG. 1B being a sectional view.

FIG. 2 is a view for explaining another embodiment of the waterproof tape of the present invention, FIG. 2 (A) is a plan view and FIG. 2 (B) is a sectional view.

FIG. 3 is an explanatory diagram of a state in which the waterproof tape is inserted in contact with the tape core wire.

FIG. 4 is a diagram showing measurement results of a prototype simulated cable.

[Explanation of symbols]

1 ... Water absorbing material, 2 ... Glass fiber, 3 ... Water-soluble binder,
11 ... Groove part, 12 ... Tape core wire, 13 ... Waterproof tape.

Claims (4)

[Claims] 1. A waterproof tape, which is housed in an optical cable using a tape core wire in which optical fiber core wires are arranged in parallel in parallel and coated so as to come into contact with the tape core wire, the waterproof tape together with a water-absorbing material A waterproof tape characterized in that a long glass fiber is included in the longitudinal direction so that the linear expansion coefficient of the waterproof tape becomes smaller than 1 × 10 −5. 2. The glass fiber and the water absorbing material are integrated by a binder, and the binder is a water-soluble extrusion material having a softening point of 60 ° C. or higher and 100 ° C. or lower. Waterproof tape described in. 3. The waterproof tape according to claim 1, wherein the glass fiber is an optical fiber. 4. The waterproof tape according to claim 3, wherein the optical fiber is used as an intervening wire for communication.