JP2000155244A - Coated optical fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coated optical fiber which can be easily inserted into a connector and prevents the optical fiber from breaking due to addition of excess stress by forming a non-peelable thin layer for a specified clad layer on the clad layer of an optical fiber. SOLUTION: The optical fiber 11 has a clad layer 11b on a core 11a. The optical fiber 11 is coated with a non-peelable thin layer 12 having good adhesion property with the clad layer 11b. The thin layer 12 consists of a fluorocarbon resin with Young's modulus at a normal temp. of 50 to 500 kg/mm2, and has <=1.0 g/mm frictional force, 2 to 15 μm thickness and 125 μm finished diameter. When the optical fiber is to be connected, only a protective coating 13 is peeled off and the fiber is connected, while the nonpeelable thin layer 12 protects the optical fiber 11. Therefore, the optical fiber 11 is not broken when the coating is peeled, or decrease in the strength due to exposure of the surface of the fiber 11 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber core having improved surface slippage of an optical fiber and preventing breakage of the optical fiber during connection.

[0002]

2. Description of the Prior Art Conventionally, as shown in FIG. 2, a Young's modulus at room temperature is 1 kgf / mm on an optical fiber 1 as shown in FIG.
A primary coating ^{2 made of} about ² or less synthetic resin and a secondary coating 3 made of synthetic resin having a Young's modulus of about several tens kgf / mm ² are sequentially applied to provide a two-layer protective coating 4. .

At the time of connection, since the coating on the optical fiber is relatively easily removed, the coating on the optical fiber is removed, and the exposed end faces of the optical fiber are butt-bonded, glued, fused or connected. Is generally used. However, such an optical fiber core wire is connected by removing the coating on the optical fiber when connecting, and thus the optical fiber may be damaged at the time of removing the coating. Further, since the surface of the optical fiber is exposed in the portion where the coating is removed, there is a problem that the strength of the optical fiber is greatly reduced. Furthermore, since the surface of the optical fiber is poor in slipperiness, in the case of connector connection, it cannot be smoothly inserted into a connector member such as a V-groove, a ferrule, or a capillary, resulting in not only poor workability but also excessive stress. As a result, the optical fiber was sometimes damaged. In addition, in connection with a crimp-type simple connector that connects by mechanical force, such as a caulking type connector or an elastic holding type connector that is being used in recent years, and an FPC (FiberPhysical Contact) connector that connects by buckling an optical fiber, There is also a problem that the possibility of disconnection is very high.

[0004] In response to these problems, recently,
On the cladding layer of the optical fiber, a high Young's modulus with good adhesion to this cladding layer (50 kg / mm ^{2 to} 300 kg / mm at room temperature)
The non-releasing of the thin layer made of urethane acrylate ultraviolet curable resin or the like of about ²⁾ is provided, on its optical fiber having a structure in which a protective coating as described above have been devised.

However, in this type of optical fiber cable, since only the outer protective coating is peeled off and connected, the strength is reduced due to the exposure of the optical fiber surface.
Although the problem of disconnection when using a crimp-type simple connector is improved, the slipperiness of the thin layer surface on the optical fiber is even less than that of the conventional bare optical fiber. And the problem of optical fiber breakage still remains.

[0006]

As described above, recently, in the optical fiber cable invented, a non-peelable thin layer is provided on the optical fiber, so that the connection of the conventional optical fiber cable is reduced. Although many of the problems described above have been improved, the problem that the optical fiber may be damaged due to the difficulty of insertion into the connector due to poor slipperiness of the peelable thin layer surface and the application of excessive stress may still be present. It was left behind.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem. By providing a non-peelable thin layer having good slipperiness on an optical fiber, insertion into a connector is facilitated. An object of the present invention is to provide an optical fiber core wire in which breakage of an optical fiber due to application of excessive stress is prevented.

[0008]

Means for Solving the Problems] optical fiber of the present invention, as described in claim 1, the optical fiber on the cladding layer, the Young's modulus at ordinary temperature of 50kg / mm ² ~500kg / mm ² It is characterized in that the clad layer is made of a synthetic resin and has a non-peeling thin layer with a frictional force of 1.0 g / mm or less.

Here, the frictional force is defined as a non-peelable thin layer inserted into an optical fiber insertion hole of a zirconia ferrule having an inner diameter of 0.1 μm to 0.3 μm having a finished diameter of the non-peelable thin layer. It is a value obtained by converting the maximum load when the optical fiber is pulled out into a stress per unit drawing length.

[0010] In such an optical fiber, the Young's modulus at room temperature of a synthetic resin of ^{50kg / mm 2 ~500kg / mm 2} , and the frictional force is less 1.0 g / mm non-releasing lamina Is provided, it is possible to insert the optical fiber smoothly into the optical fiber insertion portion of the connector without applying excessive stress. Therefore, workability is improved and breakage of the optical fiber is prevented.

[0011] The non-peeling of the thin layer to satisfy the above requirement, the Young's modulus from among fluorine-based resin having a fluorine atom in its molecule is chosen for an 50kg / mm ² ~500kg / mm ² at room temperature It can be formed by using.

Therefore, the optical fiber core of the present invention is:
As described in claim 2, on the cladding layer of the optical fiber, said cladding layer having a Young's modulus comprised from room temperature at 50kg / mm ² ~500kg / mm ² of fluororesin to comprise a non-peeling of the thin layer Including those characterized by the following.

Further, the present invention is, as described in claim 3 and 4, the outer periphery of the non-releasing of the thin layer made of a synthetic resin 10kg / mm ² ~200kg / mm ² Young's modulus at room temperature protective coating, or a Young's modulus at ordinary temperature 0.01kg / mm ² ~1kg / mm
Primary composed of ^two synthetic resin coating, and including those having a Young's modulus and having a protective coating of two-layer structure of a secondary coating of 10kg / mm ² ~200kg / mm ² of synthetic resin at room temperature.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view showing an example of the optical fiber ribbon of the present invention.

In FIG. 1, reference numeral 11 denotes an SM or GI type optical fiber in which a cladding layer 11b is provided on a core 11a. The optical fiber 11 has an adhesive property with respect to the cladding layer 11b. good frictional force consisting of fluororesin Young's modulus at ordinary temperature 50kg / mm ² ~500kg / mm ² is less than or equal to 1.0 g / mm, a thickness of 2 to 15 [mu] m, the finished diameter 12
A 5 μm non-peelable thin layer 12 is provided. Then, on the non-peelable thin layer 12, as a protective coating 13, a Young's modulus having good releasability with respect to the non-peelable thin layer 12 is 0.01 kg / mm ^{2 to} 1.0 kg / mm ^{2 at} room temperature. ^The primary coating 14, which has a finished diameter of 140 μm to 220 μm made of the synthetic resin of ² ,
Finished diameter 230Myuemu～500 [mu] m of the secondary coating 15 having a Young's modulus consisting ^{10 kg / mm 2 ~200kg / mm} 2 of synthetic resin at room temperature are provided in order.

The fluororesin constituting the non-peelable thin layer 12 is polytetrafluoroethylene (PTF).
E), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene / hexafluoropropylene copolymer (FEP),
Examples include polyvinylidene fluoride (PVDF), ethylene / tetrafluoroethylene copolymer (ETFE), polyvinyl fluoride (PVDF), and fluorinated acrylic resin. In the present invention, it is particularly preferable to use a fluorine-based acrylic resin which is liquid before curing and can be easily applied, and has a low frictional force.

The resin constituting the primary coating 14 and the secondary coating 15 satisfies the above-mentioned conditions from among UV-curable resins such as urethane acrylate, epoxy acrylate and ladder type silicone, and silicone resins. Those can be arbitrarily selected and used.

In the optical fiber core thus configured, only the protective coating 13 is peeled off at the time of connection, and the optical fiber 11 is protected by the non-peelable thin layer 12. The optical fiber 11 is not damaged at the time of removal, and there is no possibility that the strength is reduced due to the surface of the optical fiber 11 being exposed. Further, the optical fiber 1 can be used for connection by mechanical force using a simple crimp-type connector.
There is no risk of disconnection of 1. In addition, since the surface of the non-peelable thin layer 12 has good slipperiness, the connector can be easily inserted into a V-groove, a ferrule, a capillary, or the like. The breakage of the fiber 11 is also prevented. Further, since the fluororesin constituting the non-peelable thin layer 12 is excellent in water repellency, it is possible to suppress an increase in transmission loss due to contact of the optical fiber 11 with water and a deterioration due to growth of a scratch.

In the present invention, the non-peelable thin layer 1
The Young's modulus of the resin that constitutes 2 is 50kg / mm ^{2 to} 500k at room temperature.
g / mm ² is limited to a Young's modulus of 50 kg /
is less than mm ^2, occurs may be damaged when stripping the outer coating, and if conversely exceeds 500 kg / mm ^2, elongation at break is reduced, transmission characteristics loss variation due to a temperature change becomes large non This is because there is a possibility that the coating becomes sufficient or the coating peels off. More preferred Young's modulus is at room temperature
The range is from 120 kg / mm ² to 400 kg / mm ² .

The frictional force of the non-peelable thin layer 12 is
The reason for limiting the thickness to 1.0 g / mm or less is that the slipperiness of the surface becomes insufficient, which makes it difficult to insert the connector into the connector, thereby lowering workability and possibly damaging the optical fiber. . A more preferred frictional force is 0.9 g / mm or less.

Further, in this example, the non-peelable thin layer 12
Is 2 to 15 μm, which means that the thickness is 2 μm.
If it is less than μm, coating with a die becomes difficult, and sufficient strength may not be obtained.
Exceeding the range, not only may the loss fluctuation due to temperature change become large and the transmission characteristics may become insufficient, but also the outer diameter fluctuation rate is within the allowable range of ± 1.
This is because it exceeds 5%, making it difficult to connect with a simple connector. More preferred thickness is 5-10μ
m.

Further, in this example, the primary coating 14 Young's modulus are formed of a synthetic resin 0.01kg / mm ² ~1.0kg / mm ² at room temperature, because this coating is transmitted at a low temperature thereby suppress an increase in loss, and functions as a buffer layer against lateral pressure, which has the effect of suppressing an increase in transmission loss even in the Young's modulus of less than 0.01 kg / mm ² at room temperature, or 1.0 kg / mm ² This is because such an effect cannot be sufficiently obtained even if the value exceeds. For the same reason, the finished diameter of the primary coating 14 is desirably in the range of 160 μm to 210 μm as described above.

Furthermore, in this example, to the secondary coating 15 Young's modulus are formed of a synthetic resin 10kg / mm ² ~200kg / mm ² at room temperature, this coating is easy to handle as a core wire And has an effect of preventing an increase in transmission loss due to lateral pressure by being used in combination with the primary coating 14, and even if the Young's modulus at room temperature is less than 10 kg / mm ² ,
Or, even if it exceeds 200 kg / mm ² , such an effect cannot be sufficiently obtained. For the same reason, the finished diameter of the secondary coating 15 is preferably in the range of 230 μm to 300 μm as described above.

The present invention is not limited to such an example. For example, the protective coating 3 composed of only the secondary coating 15 on the non-peelable thin layer 12 may be used.
Alternatively, another coating may be provided on the secondary coating 15. Further, the optical fiber 11 in which only the non-peelable thin layer 12 is formed is useful as a core wire for an optical transmission line in a device, and the same effect as in the above example can be obtained.

[0026]

Next, examples of the present invention will be described. The Young's modulus is a value measured at a distance between gauge points of 25 mm, a tensile speed of 1 mm / min, and a 2.5% elongation measured according to JIS K 7113-1980.

EXAMPLE On a SM optical fiber having a core diameter of 9 μm, Young's modulus was 23 ° C.
180 kg / mm ² fluorine-based acrylic resin with an outer diameter of 125 μm
To form a non-peelable thin layer. Next, a urethane acrylate UV curable resin having a Young's modulus of 0.09 kg / mm ² at 23 ° C. and a Young's modulus
The 23 ° C. in a 50 kg / mm ² urethane acrylate ultraviolet curable resin, after coating the sequentially so that each outer diameter is 200μm and 250 [mu] m, by co-curing each coating was irradiated with ultraviolet rays, primary coating and secondary An optical fiber core was obtained by forming a coating.

After stripping the primary coating and the secondary coating of the obtained optical fiber core, it was inserted into a zirconia ferrule (inner diameter: 125.1 μm) of the connector, and the frictional force was measured and the occurrence rate of disconnection was examined. Was. The results were obtained with a core diameter of 9μ.
Example of Comparative Example 1 in which a SM optical fiber having a length of m (Comparative Example 1) and a non-peelable thin layer were formed of a urethane acrylate-based ultraviolet-curable resin having a Young's modulus of 23 kg at 130 kg / mm ² (Comparative Example 2) Table 1 shows the frictional force and the occurrence rate of disconnection measured in the same manner as described above.

[0029]

[Table 1] As is clear from Table 1, the optical fiber core wire according to the present invention did not break by insertion,
In the case of the comparative example, disconnection occurred frequently.

[0030]

As described above, the optical fiber core of the present invention has a non-peelable thin layer having good slipperiness on the optical fiber, so that the workability of insertion into the connector is improved, and The breakage of the optical fiber when the connector is inserted is prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of an optical fiber core of the present invention.

FIG. 2 is a cross-sectional view showing an example of a conventional optical fiber core.

[Explanation of symbols]

 11 optical fiber 11a core 11b cladding layer 12 non-peelable thin layer 13 protective coating 14 primary coating 15 secondary coating

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H050 BB04R BB04S BB05R BB05S BB07R BB07S BB08Q BB14R BB14S BB17R BB17S BB31Q BD00

Claims (6)

[Claims] To 1. A fiber optic cladding layer, it becomes a Young's modulus of from 50kg / mm ² ~500kg / mm ² of synthetic resin at room temperature,
An optical fiber core comprising a cladding layer having a frictional force of 1.0 g / mm or less and a non-peelable thin layer. To 2. A fiber optic cladding layer, the Young's modulus is provided with a non-peeling of the thin layer to said cladding layer consisting of 50kg / mm ² ~500kg / mm ² of fluororesin at room temperature Characteristic optical fiber core. The outer periphery of 3. A non-releasing of the thin layer, the Young's modulus according to claim 1, wherein further comprising a protective coating made of a synthetic resin of 10kg / mm ² ~200kg / mm ² at room temperature Optical fiber cord. The outer periphery of 4. A non-releasing of the thin layer, the Young's modulus primary coating made of a synthetic resin of 0.01kg / mm ² ~1kg / mm ² at room temperature, and Young's modulus at ordinary temperature 10kg / mm ² ~200kg 3. The optical fiber core wire according to claim 1, further comprising a protective coating having a two-layer structure of a secondary coating made of a synthetic resin having a thickness of / mm ² . 5. The optical fiber core according to claim 1, wherein a finished diameter of the non-peelable thin layer is 125 μm. 6. The optical fiber core wire according to claim 5, wherein the thickness of the non-peelable thin layer is 2 to 15 μm.