JPH02212339A - Production of loose-tube coated fiber - Google Patents

Abstract

PURPOSE:To prevent the penetration of air and to obtain loosely tubed coated optical fibers by using a resin which is transparent in a molten state after heating as a coating resin and controlling conditions in extrusion and feed while monitoring the state of a filler at the time of extrusion. CONSTITUTION:A resin which is transparent in a molten state after heating, e.g. polybutylene terephthalate resin is used as a coating resin. This resin and a jellylike mixture as a filler are extruded, loosely tubed optical fibers are drawn and coats are formed on the optical fibers. Since the extruded molten resin is transparent, the optical fibers and the filled state of the filler are observed with the naked eye through the coats and the feed speed of the filler, air cooling range (time), etc., are controlled. The loose-tube coated fibers are colored by applying ink in the same line.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a loose tube core coated with a single color that is easy to identify, and particularly to a jelly-like filling material that is filled into a tube together with a plurality of optical fiber strands. The present invention relates to a method for manufacturing a colored loose tube core wire having excellent transmission characteristics and substantially free of air bubbles.

[Conventional technology and its technical issues]

What about loose tube core wire? 1I Several optical fiber strands are coated with a jelly-like mixture filler, and the filling state of the jelly-like mixture must be bubble-free and in an appropriate amount.

In the production of such loose tube core wires.

As mentioned above, the filling state of the jelly-like mixture is extremely important; for example, if the filling amount is insufficient, air will be drawn in, causing changes in the outer diameter such as flattening of the cylindrical coating upon cooling, or On the other hand, if the filling amount is too large, the outer diameter and wall thickness of the coating will be uneven, which will have a significant negative effect on the transmission characteristics, so the filling amount of the jelly-like mixture should be
It must be controlled so that it is properly filled with just the right amount.

For the coating, an extruder with a rad die is used as usual, and a plurality of groups of optical fibers supplied with a jelly-like mixture are continuously fed into the nipple of the die, and at the same time, the tip of the nipple is A cylindrical coating is formed by continuously melting and extruding the coating resin from a ring-shaped opening surrounding the tube. The coating is applied after forming a cohesive coating, e.g.

It is cooled by a water bath at a temperature of 10-70°C.

On the other hand, loose tube core wires are colored in different colors for identification when they are made into cables, and are usually colored by mixing color patches based on inorganic pigments into resin. For this reason, since the resin to be coated is generally opaque and the inside of the coating layer cannot be observed, the jelly-like mixture is supplied by an empirically established method. Therefore, it is impossible to avoid problems such as air often entering the coating due to slight changes in operating conditions, causing it to leak outside! Formation of undesirable colored tube core wires due to defects, deterioration of transmission characteristics due to temperature, etc., was unavoidable.

Therefore, the object or technical problem of the present invention is to provide a colored loose tube core wire with excellent transmission characteristics, which does not contain air in the jelly-like mixture to be filled, and an effective method for manufacturing the same.

[Means to solve the problem]

As a result of repeated research on methods for overcoming the above technical problems, the present inventors have specifically adopted a resin that is transparent in a heated molten state, and during melt extrusion, the internal filling state can be seen through the transparent coating layer, especially jelly. It has been discovered that the above-mentioned disadvantages can be effectively resolved by controlling the extrusion conditions and feeding conditions while visually monitoring the entrainment of air into the mixture, and the present invention has been achieved based on this discovery.

That is, the present invention is a method of manufacturing a loose tube core of an optical fiber by extrusion coating with a resin, in which a resin that is transparent when heated and melted is melted and extruded from an extruder into a cylindrical shape, and the resin is filled into the cylindrical shape. A colored loose tube core wire characterized in that a plurality of optical fibers are coated to prevent air bubbles from being mixed in while seeing through the filling state of a jelly-like mixture, and then ink is applied to the surface in the same line. Provides a manufacturing method.

The coating resin used in the method of the present invention is a resin that is transparent when melted. Examples of resins suitable for coating the core wire include polybutylene terephthalate (PBT) and polyethylene.

Representative examples include crystalline resins such as nylon-12 and amorphous resins such as polycarbonate. Although these may be opaque at room temperature, it is important that they be substantially transparent when heated and molten. In addition, in this loose tube core wire, the jelly-like mixture that is filled to surround the plurality of optical fibers includes all conventionally known filling jelly-like mixtures.

The colored loose tube core wire production method of the present invention involves melting and extruding a coating resin into a cross in a ring shape from an extruder equipped with a rad die as usual, and simultaneously extruding a plurality of optical fibers to which a jelly-like mixture has been supplied. The bundle is fed into the nipple at a speed corresponding to the resin extrusion speed described above to form a cylindrical cohesive coating thereon, and the coating is then cooled in a water bath 1, for example at a temperature of 10 to 70°C.

In the above method, since the extruded molten resin is substantially transparent, the filling state of the optical fiber and the jelly-like mixture filler can be clearly seen through the coating, and the filling state can be confirmed by visual observation. You can control the feed rate of the material, or the air cooling distance J1 from when the resin coating layer adheres to the jelly-like mixture until it is cooled in the water tank! (
The method of the present invention, in which the filling amount of the jelly-like mixture can be accurately controlled by controlling the amount of time), has a technical feature in this respect, and its practical value is extremely high.

For example, if the amount of filling material is insufficient or too large, you can adjust the flow rate adjustment volume of the jelly filling machine pump and monitor the filling condition inside the tube, which is extremely easy and convenient. can form a suitable coating.

Furthermore, in the method of the present invention, the cord identification coloring applied to the resin coating layer is applied to the surface after the cord is formed. There are no particular restrictions on the coloring method, but in practice, usually, during the manufacture of the core wire, for example, after the coating has been cooled in a water tank, the surface of the moving core wire is colored with ink in the same line. Attachment is made. The ink colorant to be applied may be an inorganic pigment, an organic dye or pigment, or a mixture of two or more thereof may be used. These colorants are usually prepared into ink using a suitable medium using a resin that has good adhesion to the core wire coating resin as a binder, and are drawn in the same line in the length direction by an appropriate coating method. .

[Effect]

In the method of the present invention, the state of filling of the filler during the coating operation can be seen with the naked eye by utilizing the transparency of the coating resin discharged from the extruder when it is melted.

It is possible to effectively eliminate the inclusion of air, thereby suppressing the formation of defective core wires, and to provide colored loose tube core wires with high efficiency and excellent transmission characteristics.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 PBT was used as the core wire coating resin and polybutene mineral oil was used as the jelly-like filler, and the diameter was 3.0 mm and the inner diameter was 2.0 mm, including 10 optical fibers with a diameter of 0.25 mm.
Sono's loose tube core wire was manufactured using an extruder equipped with a cross-to-rad die while looking through the transparent resin coating layer. The resin extrusion speed was approximately 40 m/min.

The thickness of the coating was 0.5 m, and the mixture was supplied to the jelly-like filler under conditions that substantially no air bubbles were included. After confirming that the filler and the coating were in close contact, the water temperature was maintained at 60°C. It was cooled by passing it through a dripping water tank. A thin line was applied with blue ink to the coating of the core wire, which had been cooled and taken off.

The colored core wire produced in this way had transmission characteristics far superior to those produced by a conventional method over its entire length. The measured value (the measurement wavelength is

1.3 μs+) is as follows.

〔Effect of the invention〕

According to the method of the present invention, a desirable loose tube core wire with excellent transmission characteristics is effectively provided, and therefore it is extremely advantageous industrially, and its industrial utility value is extremely high.

Claims (1)

[Claims] 1. In a method of manufacturing a loose tube core of optical fiber by extrusion coating with a resin, a resin that becomes transparent when heated and melted is melted and extruded from an extruder into a cylindrical shape, and a jelly-like mixture is filled into the cylindrical shape. A method for producing colored loose tube core wire, which comprises coating a plurality of optical fiber strands to prevent air bubbles from being mixed in while seeing through the filling state of the core, and then applying ink to the surface thereof in the same line.