JPH0690343B2 - Method for forming reinforced fiber connection - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for forming a reinforced optical fiber connecting portion in which an optical fiber connecting portion is fixed to the reinforcing member with a polymer resin in the reinforcing member.

As shown in FIGS. 1 and 2, the conventional optical fiber connecting portion of this type has the optical fiber core wires 1, 1'to be connected.
With the coating layers 2 and 2'removed at the tip of the optical fiber filaments 3 and 3 ', the optical fiber filament connecting portion 4 is formed by arc fusion or the like in a state where the tips of the optical fiber filaments 3 and 3'are abutted against each other. A reinforcing member 7 including a cover 6 and a lid 6 is provided on a substrate 5 in a wire portion accommodating groove 8 and coating portion accommodating grooves 9 and 9 ′ continuous to both ends thereof, together with a silicone-based or epoxy-based polymer resin 10. It had a structure in which it was detained, and the lid 6 was tightened and fixed by adhesion.

However, the optical fiber connection portion reinforced in this way has a drawback that it causes an increase in transmission loss when a temperature change is applied and breaks the optical fiber strand when it is severe. The cause of such an increase in transmission loss and breakage of the optical fiber wire is that the bubble 11 exists in the polymer resin 10 as shown in FIG. 2 and the interface of the bubble 11 is caused by thermal strain due to temperature change. The stress is concentrated on the
This is because distortion is added to. The causes of bubble 11 are:
There are the following three points.

(A) It originally exists in the polymer resin.

(B) It occurs when a polymer resin is applied to the surface of an optical fiber element.

(C) It occurs when the polymer resin is cured.

Of these, point (A) can be solved by vacuum defoaming treatment of polymer resin, and point (B) is to keep the surface of optical fiber strand clean and devise a method for applying polymer resin. However, the point (C) remains unsolved.

The following two are considered as the mechanism of bubbles generated in the process of curing the polymer resin.

(A) The product generated during the curing reaction remains as bubbles.

(B) The curing reaction does not proceed uniformly, and as shown in FIG. 3 (A), a certain portion first cures into a shell shape, and this shell-like cured portion
The uncured portion 10B is surrounded by 10A, and the uncured portion 10B in the shell-shaped cured portion 10A contracts when the uncured portion 10B cures as shown in FIG. 3 (B). 11 occurs and is trapped.

For example, some silicone resins that are currently widely used as polymer resins for optical fiber reinforcement generate alcohol by reacting with water in the air (condensation reaction). In this case, the mechanism (a) Bubbles 11 may be generated. However, as a measure against (a), an addition reaction type polymer resin that does not generate a by-product may be used.

An object of the present invention is to provide a method for forming a reinforced optical fiber connecting portion capable of solving the problem of bubbles generated during curing of a polymer resin.

The present invention removes the coatings on the connection end sides of both optical fiber core wires to be connected to expose the optical fiber wires, respectively, and butt-connects both optical fiber wires to each other to connect the optical fiber wires. Reinforcement for forming a fiber connecting part and fixing the optical fiber connecting part and both sides of the fiber connecting part on both sides of the fiber connecting part to the reinforcing member with a polymer resin in the reinforcing member to form a fiber connecting part with reinforcement. In the method for forming an optical fiber connecting part, a curing accelerator is applied in advance to the surface of the optical fiber connecting part and both sides of the optical fiber connecting part, and then the polymer resin is injected or applied, It is characterized in that the polymer resin is cured first from the surface side of the optical fiber element and its connecting portion.

Embodiments of the present invention will be described in detail below with reference to FIGS. 1, 4, and 5. As shown in FIG. 4, the optical fiber core wires 1 and 1 ′ to be connected are formed by removing the coating layers 2 and 2 ′ at their tips to expose the optical fiber wires 3 and 3 ′ for a required length. Optical fiber connecting portions 4 are formed by abutting the tips of the wires 3 and 3'by arc welding or the like. A curing accelerator 12 is applied to the surfaces of the optical fiber connecting portions 4 and the optical fibers 3, 3'on both sides thereof. As the curing accelerator 12, for example, an alcohol solution containing cobalt naphthenate is used. Next, the optical fiber connecting portion 4 coated with the curing accelerator 12 and the optical fiber wires 3 and 3'on both sides thereof are provided on the substrate 5 of the reinforcing member 7 as shown in FIG. It is accommodated in the part accommodating groove 8 and the covering part accommodating grooves 9, 9 '. In such a state, a resin that is cured by contact with the curing accelerator 12 in each groove 8, 9, 9'is, for example, a compound having a double bond in the molecule or at the molecular end, such as a peroxide. A two-component contact-curable polymer resin 10 such as a resin containing a compound in which radical polymerization is induced by radical generation such as ethyl-peroxide, benzoyl-peroxide, tert-butylbenzoate, and cyclohexanone peroxide is injected or applied to form a photopolymerizable resin. The outer peripheries of the fiber strand connecting portions 4, the optical fiber strands 3 and 3 ', and the coating layers 2 and 2'are coated as shown in FIG. 5, and the lid 6 is closed. When the polymer resin 10 is cured in this state, the curing accelerator 12 is applied to the surfaces of the optical fiber connecting portion 4 and the optical fiber wires 3 and 3'on both sides thereof. Starts curing from the surface side of the optical fiber connecting portion 4 and the optical fiber 3, 3 '. Therefore, the bubbles 11 are not trapped in the polymer resin 10 in the vicinity of the surfaces of the optical fiber connecting portion 4 and the optical fiber strands 3 and 3 ', and as shown in FIG. It becomes the resin layer 10A. The surface of the polymer resin 10 is bonded to the substrate 5 and the lid 6 of the reinforcing member 7.

When the bubble-free polymer resin layer 10A is formed in this manner,
The bubble 11 is the optical fiber connecting portion 4 and each optical fiber.
The non-foamed polymer resin 10A does not come into contact with or come close to the surfaces of 3, 3 ', and acts as a buffer layer against the stress caused by the bubble 11, increasing the transmission loss due to the bubble 11 and the optical fiber strand 3. It is possible to prevent breakage of 3 '.

As described above, in the method for forming a reinforcing optical fiber connecting portion according to the present invention, a curing accelerator is applied in advance to the surface of the optical fiber connecting portion and the optical fiber wires on both sides thereof, and then the polymer is added. Since the resin is injected or applied, it is possible to start the curing of the polymer resin from the optical fiber connecting portion and the surface side of the optical fiber, and accordingly, the optical fiber connecting portion during the curing of the polymer resin. Also, the bubble-free polymer resin layer can be formed without trapping bubbles on the surface of the optical fiber element. Therefore, according to the reinforcing optical fiber connecting portion formed by the method of the present invention, bubbles do not come into contact with or come close to the optical fiber connecting portion and the surfaces of the optical fiber connecting wires on both sides thereof, and the bubble-free height is high. The molecular resin layer acts as a buffer layer against the stress caused by the bubbles, and it is possible to prevent an increase in transmission loss and breakage of the optical fiber wires due to the bubbles.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a reinforcing optical fiber connecting portion during assembly, and FIG. 2 is an optical fiber strand in a conventional reinforcing optical fiber connecting portion and a polymer for the connecting portion. FIG. 3A, FIG. 3B, and FIG. 3C are explanatory views showing a process in which air bubbles are trapped in the polymer resin.
FIG. 4 is a perspective view of the step of applying a curing accelerator in the method of the present invention, and FIG. 5 is an optical fiber strand in the reinforcing optical fiber connecting portion formed by the method of the present invention and a polymer resin for the connecting portion. It is a longitudinal cross-sectional view showing an example of the covered state of. 1,1 '…… Optical fiber element wire, 4 …… Optical fiber element wire connection part, 5 …… Substrate, 6 …… Lid, 7 …… Reinforcing member, 8 …… Element wire part accommodating groove, 9,9 ′ …… Coating part accommodating groove, 10 …… Polymer resin, 10A …… Bubbles-free polymer resin layer, 11 …… Bubbles, 12 ……
Curing accelerator.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshio Tsuchida 6 Hachiman Kaigan Dori, Ichihara City, Chiba Prefecture Furukawa Electric Co., Ltd. Chiba Electric Wire Works (72) Inventor, Michito Matsumoto, Tokai-mura, Ibaraki Prefecture. 162 Shirahone, Nippon Telegraph and Telephone Public Corporation Ibaraki Research Institute of Electrical Communication

Claims (1)

[Claims] 1. An optical fiber is formed by removing coatings on the connection end sides of both optical fiber core wires to be connected to expose the optical fiber wires, and connecting both optical fiber wires to each other by butt connection. A fiber connecting part is formed, and the periphery of the fiber connecting part and the fiber connecting wires on both sides of the fiber connecting part are fixed to the reinforcing member with a polymer resin in a reinforcing member to form a fiber reinforced connecting part. In the method of forming a reinforced optical fiber connecting portion, a curing accelerator is previously applied to the surface of the optical fiber connecting portion and the optical fiber wires on both sides of the connecting portion, and then the polymer resin is injected or applied. A method for forming a reinforced optical fiber connecting portion, characterized in that the polymer resin is cured first from the surface side of the optical fiber strand and its connecting portion.