JPH075448Y2 - Fiber optic cable - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an optical fiber having an improved water absorbing yarn to be filled in a slot portion of an optical fiber cable used for a communication line in which an optical fiber core wire is not arranged.

<Prior Art> In a fiber optic cable that is generally used for a communication line, if a damaged portion occurs in part, water will enter the cable due to this damage. As this water runs in the longitudinal direction, the optical fiber core wire is immersed in the water. If the optical fiber core wire is immersed in water for a long time, the strength of the optical fiber core is lowered, and there is a risk that the optical fiber core wire may be broken in the worst case due to the tension.

In order to solve such a problem, a waterproof cable using a water absorbent resin is used, and this water absorbent resin is
It is used for the cable winding part, the slot part where the optical fiber core wire is arranged, and the slot part where the optical fiber core wire is not arranged.

Among them, as a method of waterproofing the slot part where the optical fiber core wire is not arranged, dip nylon fiber or polyethylene terephthalate fiber (hereinafter PET fiber), which has strength and waterproofness, in a mixed liquid of a water absorbent resin and a binder resin, Squeeze,
A method of filling this into a cable is used.

<Problems to be Solved> Among the conventional techniques, the fibers to which the mixed liquid of the water-absorbent resin and the binder resin adheres become flat when squeezed out, and thus lacks the mechanical filling property when filling the cable.

Further, since the binder resin adhered to the fibers is cured, the water absorbent resin surrounded by the cured binder resin cannot contact the invading water. And, in fact, only the water-absorbent resin on the surface that can come into contact with water absorbs water.
Since it swells, there is a problem that both the water absorption capacity and the water stopping capacity are small.

In view of the above problems, the present invention not only provides waterproofness to an optical fiber cable, but also has a water-stopping / water-absorbing ability and stability of strength, and a slot type excellent in handleability at the time of connection in cable manufacturing. It is intended to provide an optical fiber cable.

<Means for solving the problem> Water absorption with a string-like product formed by bundling a large number of water-absorbent fibers with a nylon yarn or polyethylene terephthalate yarn, etc., which has strength and waterproofness, to keep it flat and cushioning. The problem was solved by arranging the yarn in the slot portion in the slot type optical fiber cable where the optical fiber core wire is not arranged.

Here, the water-absorbent yarn has a fiber such as acrylic as an inner layer,
Water-absorbing fibers having a two-layer structure with a water-absorbing resin such as ammonium polyacrylate as the outer layer absorbs water and swells.
Use a nylon-based or PET yarn that is waterproof, with a flat surface and a cushioning effect.

<Operation> Water that has infiltrated from the damaged portion of the optical fiber cable and reaches the slot portion where the optical fiber core wire is not arranged can be prevented from running by the water absorbing yarn.

Moreover, since the water-absorbent yarn has a cushioning property, the water-absorbent yarn spreads widely in the slot and the gap inside the water-absorbent yarn becomes large. Therefore, the invading water can easily pass through the inside of the water absorbing yarn, so that the water absorbing yarn can have a large water absorbing area, and the water absorbing speed and the water absorbing amount are large.

In addition, the strength of the water-absorbent yarn is stable, it is hard to be loosened, and it is not flat because the nylon yarn or polyethylene terephthalate yarn, which has strength and waterproofness, is twisted. Therefore, the water-absorbent yarn has a stable mechanical filling property, and has sufficient handleability at the time of manufacturing and connecting the cable.

<Embodiment> FIG. 1 is a partially broken explanatory view of a waterproof type slot-type optical fiber cable, in which 1 is a slot rod having a slot portion 2, 3 is an optical fiber core wire, 4 is an inclusion, 5
Is a press-wound layer, and 6 is a jacket layer. The optical fiber core wire 3 is arranged in three of the four slot portions 2, and the optical fiber core wire is not arranged in the other one slot portion 2. Is an optical fiber cable.

Here, the inclusions 4 and the press-winding layer 5 are provided with a water-absorbent resin, and the inclusions are 1.2 to 1.5 mm strip-shaped tapes.

The water-absorbent yarn 10 is made of water-absorbent fiber as shown in FIG.
This is a structure in which a string-like product obtained by bundling a large number of 11 is twisted in a non-flat shape with a thread 12 having excellent strength and waterproofness.

Next, a specific example of the water absorbing yarn 10 will be described.

The following tests were conducted using a string-like product in which a large number of water-absorbent fibers treated with poly (ammonium acrylate) were bundled on the outside of acrylic fibers, and a water-absorbing yarn in which several nylon yarns were applied 25 times / m. It was

10 water absorbent yarns of the above structure with a length of 1 m each with an inner diameter of 5 mm
The water running state was observed by applying a water head pressure of 1.2 m to one end of the tube.

The average running length was 30 cm.

<Effect of the Invention> As described above, according to the present invention, the slotted portion where the optical fiber core wire is not arranged is provided with the water-absorbing yarn, which is formed by the string-shaped product formed by bundling the water-absorbing fibers. Since it has a property, it is possible to reliably prevent running water from entering.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional explanatory view showing an example of a slot type optical fiber cable, and FIG. 2 is an explanatory view of a water absorbing yarn. 1 ... slot rod, 2 ... slot part 3 ... optical fiber core wire, 4 ... inclusions 5 ... holding layer, 6 ... envelope layer 10 ... water absorbing yarn, 11 ... water absorbing fiber 12 ... yarn

Claims (1)

[Scope of utility model registration request] 1. A water-absorbing yarn obtained by twisting a non-flat twist of a string-like product in which a large number of water-absorbing fibers are bundled in a slot portion of a slot-type optical fiber cable in which no optical fiber core wire is arranged. A fiber optic cable characterized in that