JP2004184880A - Coating structure of thin film optical fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coated optical fiber which has a thin film resin layer stopped from peeling off a clad by using a UV curing resin having a low adhesive strength in a second layered coating layer. <P>SOLUTION: In a coating structure of a coated optical fiber 10 where two or three-layered protection coating layers 15 and 16 are provided on a thin film coating layer 14 coating a bare optical fiber 13, the second layered coating layer 15 coated following the thin film coating layer 14 is made of a UV curing resin in which the adhesive strength to the thin film coating layer 14 is ≤40g/mm. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００１４】
以上の結果から、第２層目の被覆層１５の薄膜被覆層１４に対する密着力を４０ｇ／ｍｍ以下とすれば、光ファイバの接続時等において外層被覆を剥ぐ必要が生じた場合、ほぼ第２層目被覆層１５，第３層目被覆層１６の保護被覆層のみが剥ぎ取られ、薄膜被覆層１４がクラッド１２から剥離するのを顕著に低減し、薄膜被覆層１４にまで影響が及ぶことが可及的に抑制されるので、伝送特性の劣化も回避でき、上述のように密着力を４０ｇ／ｍｍ以下としても実用上差し支えない。
【００１５】
【発明の効果】
本発明によれば、次のような効果が得られる。
（ａ）請求項１の発明によれば、薄膜被覆層に対する密着力が４０ｇ／ｍｍ以下であれば、薄膜樹脂層がクラッドから剥離することを抑制することができる。
【図面の簡単な説明】
【図１】本発明の光ファイバ心線の断面図である。
【図２】評価テストに用いた冶具の概略図である。
【図３】従来の光ファイバ心線の断面図である。
【符号の説明】
１，１１・・・コア
２，１２・・・クラッド
３，１３・・・光ファイバ裸線
４・・・薄膜樹脂層
５・・・第２層目被覆層
６・・・第３層目被覆層
７，１０・・・光ファイバ心線
１４・・・薄膜被覆層
１５・・・２層目となるソフトＵＶ被覆層（第２層目被覆層）
１６・・・３層目となるハードＵＶ被覆層（第３層目被覆層）
２０・・・固定具
２１・・・ロードセル[0001]
[Industrial applications]
The present invention relates to a thin-film optical fiber coating structure in which two or three protective coating layers are provided on a thin-film coating layer covering an optical fiber bare wire.
[0002]
[Prior art]
In recent years, when connecting optical fibers, a method of connecting using a crimp-type connector has been frequently used, and accordingly, a non-adhesive layer having good adhesion to the cladding layer on the cladding layer constituting the bare optical fiber has been used. It is known to coat a releasable thin film coating layer. (See Patent Document 1)
[0003]
FIG. 3 is a cross-sectional view of an optical fiber core having such a thin film coating layer. A thin film having good adhesion is formed on a bare SM optical fiber 3 having a core 1 and a clad 2 having a thickness of 5 μm to 15 μm. A non-peelable UV-curable resin is coated (thin film resin layer 4). The outer diameter of the thin-film resin layer 4 is 125 μm, and a second coating layer 5 and a third coating layer 6 made of UV-curable resin are further coated thereon as a protective coating layer. 7 is finished.
[0004]
[Patent Document 1]
JP-A-2000-81552 (page 2-3, FIG. 1)
[0005]
[Problems to be solved by the invention]
However, when the conventional optical fiber core 7 described above is used, only the outer second-layer coating layer 5 and the third-layer coating layer 6 are peeled off and connected, but the second-layer coating layer is used. No consideration is given to the adhesive force of the thin film resin layer 4 to the thin film resin layer 4. For example, if the adhesive force is large, the thin film resin layer 4 may be separated from the clad 2.
[0006]
The present invention has been made in view of such circumstances, and an object of the present invention is to use a low-adhesion type UV-curable resin for a second coating layer and peel a thin film resin layer from a clad. An object of the present invention is to provide a thin-film optical fiber that suppresses the occurrence of the above.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, a coating structure of a thin film optical fiber according to the present invention is a coating structure of a thin film optical fiber in which a protective coating layer composed of two or three layers is provided on a thin film coating layer covering an optical fiber bare wire. The second coating layer to be coated next to the thin film coating layer is an ultraviolet curable resin having an adhesion to the thin film coating layer of 40 g / mm or less.
In this way, if the adhesion to the thin film coating layer is 40 g / mm or less, the thin film resin layer can be prevented from peeling from the clad.
[0008]
【Example】
FIG. 1 is a sectional view of an optical fiber core of the present invention. Hereinafter, the structure of the optical fiber core of the present invention will be described with reference to FIG.
Reference numeral 10 denotes an optical fiber core, which is a bare optical fiber 13 having a glass fiber core 11 and a clad 12 at the center, and a thin film made of resin for protecting the bare wire surrounding the outer periphery and compensating for mechanical strength. (A thin film coating layer) 14.
[0009]
The thin film coating layer 14 has a finished outer diameter of about 125 μm, is formed of a UV-curable (ultraviolet-curable) resin, and is coated on the clad 12 so as not to peel off.
[0010]
The outer periphery of the thin film coating layer 14 is further coated with a soft UV coating layer (second coating layer) 15 as a second layer and a hard UV coating layer (third layer coating layer) 16 as a third layer. Have been. It is desirable that the second and third coating layers 15 and 16 have a large effect of protecting the bare optical fiber 13, that is, a layer capable of suppressing transmission loss due to lateral pressure and temperature change.
[0011]
Therefore, a number of optical fiber core wires in which the adhesion force of the second coating layer 15 to the thin film coating layer 14 was variously changed were prepared, and an evaluation test of the adhesion force was performed. FIG. 2 is a schematic diagram of the jig used for the evaluation test.
[0012]
In FIG. 2, the optical fiber core 10 is bonded to a fixture 20 having a groove corresponding to the core diameter for a predetermined length, and is applied to the second and third coating layers 15 and 16 at a pulling speed of 3 mm / min. Circular cuts are made, and quartz glass with the first thin film coating layer 14 applied thereto is drawn out of the second and third coating layers 15 and 16 to an arbitrary length. The stress was measured by the load cell 21. The magnitude of the adhesive force is a value obtained by dividing the maximum stress acting on the core by the length of the core fixed to the fixture 20.
[0013]
The test results show that, as shown in Table 1, the peeling of the thin film coating layer 14 was as small as 5% or less when the adhesive force was approximately 40 g / mm or less, and the thin film coating layer 14 was peeled when the adhesive force was increased to 50 g / mm. It was found that the frequency at which the film was formed increased to 40%, and when the adhesion became 150 g / mm, the thin film coating layer 14 was peeled at a rate of almost 100%.
[Table 1]

[0014]
From the above results, if the adhesion of the second coating layer 15 to the thin film coating layer 14 is set to 40 g / mm or less, when the outer layer coating needs to be peeled off at the time of connection of an optical fiber or the like, almost the second Only the protective coating layers of the layer coating layer 15 and the third layer coating layer 16 are peeled off, and the peeling of the thin film coating layer 14 from the clad 12 is remarkably reduced, and the thin film coating layer 14 is affected. Is suppressed as much as possible, deterioration of the transmission characteristics can be avoided, and even if the adhesion is set to 40 g / mm or less as described above, there is no practical problem.
[0015]
【The invention's effect】
According to the present invention, the following effects can be obtained.
(A) According to the first aspect of the invention, if the adhesive force to the thin film coating layer is 40 g / mm or less, the thin film resin layer can be prevented from peeling from the clad.
[Brief description of the drawings]
FIG. 1 is a sectional view of an optical fiber core of the present invention.
FIG. 2 is a schematic diagram of a jig used for an evaluation test.
FIG. 3 is a cross-sectional view of a conventional optical fiber.
[Explanation of symbols]
1, 11 ... core 2, 12 ... clad 3, 13 ... bare optical fiber 4 ... thin film resin layer 5 ... second layer coating layer 6 ... third layer coating Layers 7, 10 Optical fiber core wire 14 Thin film coating layer 15 Soft UV coating layer to be the second layer (second coating layer)
16: Hard UV coating layer to be the third layer (third layer coating layer)
20: Fixture 21: Load cell

Claims (1)

A coating structure for a thin-film optical fiber in which a protective coating layer composed of two or three layers is provided on a thin-film coating layer that covers an optical fiber bare wire, wherein the second coating layer is coated next to the thin-film coating layer Is a coating structure of a thin-film optical fiber which is an ultraviolet-curable resin having an adhesion to the thin-film coating layer of 40 g / mm or less.

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