JPH0363611A - Coating structure and coating method for optical fiber - Google Patents

Abstract

PURPOSE:To improve the adhesiveness of the outside surface of a coating and to facilitate the handling of an optical fiber in the post-treatment thereof by securely sticking powder to the outside surface of the coating of the optical fiber. CONSTITUTION:The fiber of the optical fiber 2 is passed through a thermoplastic resin 24 in a molten state in a coating device 18, by which the coating 4 is formed on the outside surface of the fiber. This fiber is in succession passed through a powder sticking device 20 and the powder 10 housed in a housing chamber 26 is blown together with the air flow of a powder supply pipe 30 to the coating 4 to securely stick the powder 20 to the coating 4 at the temp. higher than the temp. of the thermoplastic resin. As a result, the adhesiveness of the coating 4 is improved and the handling is facilitated when a connector is mounted to the optical fiber or when an optical cable is formed by bundling the plural optical fibers.

Description

Detailed Description of the Invention Overview Regarding a coating structure and a coating method for an optical fiber, an object of the present invention is to provide a coating structure and a coating method for an optical fiber in which the outer surface of the coating has excellent adhesion. A coating structure for an optical fiber is constructed by firmly adhering powder to the outer surface of the coating.

Industrial applications The present invention relates to an optical fiber coating structure and coating method.

Optical fibers used in the field of optical fiber transmission are easily damaged when they are spun from a preform and can significantly reduce their strength, so they are usually coated after being spun before being put into practical use. IL. Therefore, in processing such as when attaching an optical connector to an optical fiber, it is necessary to handle the optical fiber including coating, and a coating structure and coating method suitable for the processing are required.

Prior Art As an example of a conventional coating structure for an optical fiber, a buffer layer of silicone resin or the like is formed on the outer periphery of an optical fiber immediately after spinning to form an optical fiber strand, and nylon or the like is further coated on the outer periphery of this optical fiber strand. Some optical fibers are coated with a thermoplastic resin. When an optical fiber and its coating are inserted and fixed into a ferrule in order to attach an optical connector to the end of this type of optical fiber core wire, the method shown in FIG. 5 is used. That is, the optical fiber 2 from which the coating in the vicinity of the end portion has been removed is inserted into the ferrule 6 together with the coating 4 from which the coating has not been removed, and is fixed with an adhesive 8. The ferrule 6 is continuously formed with an insertion hole 6a having an inner diameter corresponding to the outer diameter of the optical fiber 2 and an insertion hole 6b having an inner diameter corresponding to the outer diameter of the coating 4. It will be inserted to the corresponding position.

Problems to be Solved by the Invention Conventional coating structures for optical fibers generally involve attaching a thermoplastic resin to the outer periphery of the optical fiber either directly or indirectly through a buffer layer, and then cooling and solidifying the resin. ,
The outer surface of the coating is extremely flat due to the surface tension that acts when the thermoplastic resin is melted. For this reason, when trying to fix an optical fiber and its coating using an adhesive as shown in Figure 5, the adhesion of the outer surface of the coating is not good, and the adhesive easily peels off, causing the optical fiber to become light. Undesirable forces are applied to the fiber, which may cause characteristic changes or breakage.

In order to deal with such problems, conventionally, the outer surface of the coating was sometimes scratched using sandpaper, etc., but in this case, not only did it require complicated work, but also It is difficult to uniformly scratch the outer surface.

The present invention was created in view of these circumstances, and aims to provide an optical fiber coating structure and coating method in which the outer surface of the coating has excellent adhesive properties.

Means for Solving the Problems The above-mentioned technical problem is solved in an optical fiber coating structure in which a coating 4 is applied to the outer periphery of an optical fiber 2, as shown in FIG. This problem can be solved by firmly adhering the powder 10 to the surface.

In the figure, 2a indicates the core of the optical fiber, and 2b indicates the cladding of the optical fiber.

Furthermore, focusing on the fact that the coating applied to the outer periphery of an optical fiber is generally composed of thermoplastic resin, we proposed two coating methods suitable for realizing the above coating structure. -ru.

The first method is to apply a coating 4 made of thermoplastic resin to the outer periphery of the optical fiber 2 after spinning, and then spray powder 10 onto the coating 4 at a temperature higher than the melting point of the thermoplastic resin to obtain iron powder. The body 10 is firmly attached to the outer surface of the coating 4.

In the second method, a coating 4 made of a thermoplastic resin is applied to the outer periphery of the optical fiber 2 after spinning, and then the optical fiber 2 and coating 4 are coated in a powder 10 at a temperature higher than the melting point of the thermoplastic resin. The powder 10 is made to firmly adhere to the outer surface of the coating 4 by passing through it.

Function According to the optical fiber coating structure described above, since the powder 10 is firmly attached to the outer surface of the coating 4, the outer surface of the coating 4 is smooth compared to the case where the outer surface of the coating 4 is smooth. The affinity of the surface for adhesives increases, improving adhesion.

Furthermore, according to the first or second method, the coating 4 is formed from a thermoplastic resin, and the powder 10 is brought into contact with the coating 4 at a temperature higher than the melting point of the thermoplastic resin. The particles are incorporated into the surface layer of the coating which is in a molten and softened state, and the powder easily becomes firmly attached to the outer surface of the coating.

Example Embodiments of the present invention will be described below based on the drawings.

FIG. 2 is a sectional view of an optical fiber coating structure showing an embodiment. In this example, the outer surface of an optical fiber 2 consisting of a core 2a and a cladding 2b is covered with a buffer layer 12 made of silicone resin or the like to form an optical fiber wire 14. A coating 4 made of plastic resin is applied, and powder 10 is firmly attached to the outer surface of the coating 4 by the first or second method to form an optical fiber core 16.
It is said that As the powder 10, Ti○2 powder, 310
Powders that do not easily deteriorate in quality, such as Al2O5 powder and Al2O5 powder, can be used. In this case, the coating 4 melts and
Powder 10 is attached in an oxidized state, so powder 1
0 may be taken into the coating 4, but powder 1
Since zero does not reach the outer surface of the buffer layer 12 or penetrate through the buffer layer 12 to reach the optical fiber 2, there is no risk of strength problems. Note that if the particle size of the powder 10 is too large or small, it will easily fall off from the coating 4, so it is desirable that the particle size is in the range of 10 μm to several 100 μm.

According to this coating structure, when an optical fiber is terminal-treated as shown in FIG. 5, for example, it is possible to firmly fix the coating to the ferrule, which solves the problems in the conventional technology. .

FIG. 3 is an explanatory diagram of an optical fiber coating process showing an example, in which the first method is applied. This coating process is
A coating device 18, a powder adhesion device 20, and a cooling tank 22 are arranged in this order along the optical fiber 14 that is being sent out at a constant speed. 24
indicates a thermoplastic resin in a molten state housed in the coating device 18, through which the coating 4 is applied to the outer surface of the optical fiber 14 by passing the optical fiber strand 14 therethrough. It has become. Further, the powder adhesion device 20 is
It is positioned sufficiently close to the coating device 18 to deposit the powder before the coating 4 applied to the optical fiber strand 14 hardens. In the powder deposition device 20, the powder 10 accommodated in the storage tank 26 is supplied into the supply pipe 30 via the powder flow path 28 by gravity and/or the negative air pressure in the powder supply pipe 30. The powder 10 supplied into the supply pipe 30 is blown onto the outer surface of the optical fiber strand 14 together with the air flow within the powder supply pipe 30. In addition, the tip of the powder supply pipe 30 is divided into two, and the powder supply pipe 30
are provided in two symmetrical positions with respect to the optical fiber wire 14. A cover 32 covers at least the outlet of the powder supply pipe 30 to prevent the powder 10 blown out from the powder supply pipe 30 from scattering, and is connected to an exhaust facility (not shown). The cooling tank 22 is configured to allow cooling water to overflow, and the optical fiber 14 passes through the overflowing cooling water.

According to this coating process, since the powder deposition device 20 is disposed immediately after the coating device 18, the powder can be sprayed onto the coating which is in a molten state at a temperature higher than the melting point of the thermoplastic resin 24. , it is easy to firmly adhere the powder to the outer surface of the coating.

FIG. 4 is an explanatory diagram of another powder deposition device that can be used in the process shown in FIG. 3, and is suitable for implementing the second method. In this device, a powder storage tank 34 containing powder 10 is placed immediately after a coating device 18, and the optical fiber 14 is coated with a coating 4 at a temperature higher than the melting point of the thermoplastic resin 24. The powder 10 is passed through the powder 10 so that the powder 10 is firmly attached to the outer surface of the coating 4.

In this embodiment as well, the covering structure shown in FIG. 2 can be obtained as in the previous embodiment.

In the embodiment described above, the powder deposition device is used as the coating device 18.
The optical fiber core is placed immediately after the coating so that the powder adheres to it before the applied coating hardens. The powder may be applied by melting the coating again while unwinding the wire. By doing so, the powder can be applied only to desired positions as necessary.

As described in detail of the invention, in the optical fiber coating structure in which the outer periphery of the optical fiber is coated, the adhesion of the outer surface of the coating is improved by firmly adhering powder to the outer surface of the coating. It becomes possible to do so. Moreover, according to the first or second coating method, the above-mentioned coating structure can be easily obtained. Furthermore, the above-mentioned coating structure not only improves the adhesion of the outer surface of the coating, but also has the effect of making it difficult to slip when holding optical fibers together. Another effect is that when bundled to form an optical fiber cable, the optical fiber core wires become less likely to slip against each other, thereby preventing cable deformation.

4 is an explanatory diagram of another powder deposition device that can be used in the process shown in FIG. 3, and FIG. 5 is a cutaway side view showing a state in which an optical fiber and its coating are inserted and fixed into a ferrule. It is.

2...optical fiber, 4...Coating, 10...Powder.

Claims (3)

[Claims] (1) An optical fiber coating structure in which a coating (4) is applied to the outer periphery of an optical fiber (2), characterized in that powder (10) is firmly attached to the outer surface of the coating (4). Optical fiber coating structure. (2) After applying a coating (4) made of a thermoplastic resin to the outer periphery of the spun optical fiber (2), powder (10) is applied to the coating (4) at a temperature higher than the melting point of the thermoplastic resin. A method for coating an optical fiber, characterized in that the powder (10) is firmly adhered to the outer surface of the coating (4) by spraying. (3) After applying a coating (4) made of a thermoplastic resin to the outer periphery of the spun optical fiber (2), the optical fiber (2) and the coating (4) are heated at a temperature higher than the melting point of the thermoplastic resin.
) is passed through a powder (10) to firmly adhere the powder (10) to the outer surface of the coating (4).