JPH03187956A - Carbon-coated fiber - Google Patents

Abstract

PURPOSE:To improve the mechanical strength and environmental resistance of a quartz optical fiber by forming a carbon coating layer having a specific thickness on the outer periphery of the fiber. CONSTITUTION:A hydrocarbon such as C2H2 or a halogenated hydrocarbon such as CCl4 as a raw material is pyrolyzed on a quartz optical fiber to deposit carbon fine particles having a diameter of <10Angstrom on the fiber for forming a carbon coating layer having a thickness of 10-100Angstrom , thereby providing a carbon-coated fiber having a high strength, slightly broken and having excellent environmental resistance. A coating layer comprising an organic resin, etc., can be, if necessary, further formed on the outer periphery of the carbon-coated fiber.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a carbon coating layer on the outer periphery of a quartz-based optical fiber.
It is a carbon-coated fiber two-J-ru product made of carbon coated fiber.

1. Prior Art Silica-based optical fibers lack reliability in mechanical strength due to their extremely small diameter and the characteristics of their materials.

Therefore, as a measure to improve mechanical strength, attempts have been made to apply a thin coating (also called a hermetic coating) around the glass fiber with an inorganic material. Among many inorganic materials, carbon (C) is the most typical coating material [for example,
Publication No. 0363, EP0308143, Ni, C.
Baek, [Journal Eve Light Unive Chikunoroshii] vol.1. L T-4, No. 8.1048~
References such as p. 1060 (August 1986)].

These hermetic coats do not allow H and O to pass through, so fibers equipped with them are less likely to break.
Good static fatigue properties; ■Excellent H2 resistance properties;
■Excellent chemical resistance (alkali and others), which has advantages such as ■ through ■.

As a supplement to the above (■), the breakage of the glass fiber is caused by the reaction between H2O and glass as shown below, resulting in 5i-
It is thought that this occurs when the 0-3i bond is broken, so it is important to prevent H and O from passing through the coating material around the fiber to prevent breakage.

OH0H 8r-0-8+-1-11yO→-si+5i1-Problem to be Solved by the Invention 1 Carbon coated fibers have the above-mentioned advantages, but on the other hand, they have the disadvantage of low tensile strength.

This is considered to be due to the fact that the carbon coating is performed using the CVD (chemical vapor deposition) method.

In the mechanism of the CVD method in which carbon particles generated in a gas phase are deposited on the quartz surface, it is considered almost impossible to avoid the carbon particles from damaging the quartz surface.

In view of the current situation, it is an object of the present invention to provide a carbon foot fiber member without deterioration in tensile strength.

[Means for Solving the Problems] As a result of intensive research, the present inventors have found that in a carbon coated fiber having a carbon coating layer on the outer periphery of a silica-based optical fiber, the thickness of the carbon coating layer is 10 to 100 mm. The inventors have found that carbon foot fibers characterized by being human can achieve the two objectives.

FIG. 1 is a sectional view of a specific example of the present invention, in which a carbon coating layer 2 of 10 to 100 layers is coated on the outer periphery of one glass fiber.
is the provision. Although not shown in FIG. 1, a coating layer made of an organic resin or the like can be further provided on the outer periphery of the carbon coating layer by means known in this type of technical field.

As long as the glass fiber C according to the present invention is made of quartz-based glass, there are no particular limitations on the material composition or fiber structure, and the cladding may be pure quartz, quartz doped with fluorine, etc. Furthermore, various materials such as one in which the outermost layer is doped with T + Ov can be used as the stress applying portion.

The carbon coating layer with a thickness of 10 to 100 people around the outer periphery of the glass fiber is produced by thermally decomposing the raw material on the glass fiber using, for example, hydrocarbons such as C, H, and halogenated hydrocarbons such as CCa as raw materials. It can be formed by precipitating and depositing carbon fine particles of about 1 to 10 particles on the surface of a glass fiber. It is easy to adjust the film thickness by adjusting the raw material concentration.

[Function] There are the following two types of surface flaws that affect the strength of carbon coated fibers.

1) Network formation of 5i-0 in quartz-L Scratches due to unevenness that inevitably occur.

2) Macro scratches caused on the surface by external factors.

FIG. 2 shows the results of a tensile strength test of a normal quartz fiber (without a carbon coating layer). The horizontal axis shows the tensile strength (
kg), and the probability of breakage (%) is plotted on the vertical axis, and is plotted as a Weibull plot. Usually, a silica fiber with an outer diameter of 125 μm breaks only when a tensile strength of about 6 kg is applied due to the presence of the microscopic flaws described in 1) above. However, because dust in the air and other factors during wire drawing cause scratches on the surface (see item 2 above), there are always low-strength parts that will break if a tensile strength of only 2 to 3 kg is applied. are doing.

FIG. 3 shows the results of a tensile test of carbon coated fibers with a carbon film thickness of 300 people, similar to FIG. 2. Unlike ordinary optical fibers, there is no low-strength part that breaks at about 2 to 3 kg, and the carbon coating prevents scratches on the quartz surface from being caused by external factors during manufacturing, such as dust in the air. On the other hand, the part that breaks at about 6 kg, which reflects the unevenness of the 5i-0 quartz network, disappears, which suggests that very fine scratches were caused by carbon particles during carbon coating. [See the above-mentioned paper by Nie, C., and Pek].

Therefore, the present inventors came up with a method of coating a very thin (carbon layer) to leave the high-strength parts and eliminate the low-strength parts, and through experiments, they found that they could create a carbon-coated fiber with the desired tensile strength. I was able to make it happen.

In the present invention, the thickness of the carbon coating layer is 10 to 10
Preferably 0 people. The reason for setting the lower limit at 10 is that this is the thickness necessary to form a film uniformly, and the upper limit of 10
This is because if the carbon coating is applied to a thickness greater than this, it will lead to the formation of macro scratches (strength: 6 kg).

Although it may be felt that making the carbon film too thin is disadvantageous in terms of blocking the influence of the external environment, which is the 11-I point of carbon coating, 11. Considering the fact that breakage due to penetration occurs from low-strength parts in the first place, there is no significant disadvantage in practice. Furthermore, it is clear that the fiber has better characteristics than ordinary fibers in terms of H resistance and characteristics.

[Example] Example 1 Carbon coated fibers having various film thicknesses shown in Table 1 were produced, and the carbon coated fibers were pulled until they broke while measuring the tension, and the tension at break (tensile strength) was measured. compared. The film thickness was measured using Auger electron spectroscopy. The measurement results are also shown in Table 1.

Table 1 As is clear from the results in Table 1, the tensile strength increases when the film thickness is 10 to 100. In addition, the tensile strength of 200 Å or more is rather reduced.

Example 2 The carbon coated fiber shown in Table 1 had a film thickness of O(
Table 2 shows the results of the comparison of various properties of three products: 50 people (comparative product), 50 people (inventive product), and 300 people (comparative product). The implementation mode of each test is as follows.

Dynamic fatigue characteristics Note 1): Fatigue parameters obtained from dynamic fatigue tests. By tensile method. Gauge length 20 cm, strain rate 5-100%/min, number of samples 20, 25° C., 50% RH0 Static fatigue characteristics 2): These are fatigue parameters determined from a static fatigue test. Wrapping is according to the law. Mandrel diameter 3.0~4, 0 mmφ,
Number of samples: 20, 25°C, 50% Rl-1.

H resistance properties 1j3); Increase in hydrogen peak when immersed for 20 hours in an atmosphere of 100℃, time of.

0 From the results of the above examples, it can be seen that the carbon coated fiber of the present invention is an optical fiber with high strength, excellent fatigue properties, and excellent environmental resistance.

[Effects of the Invention] As explained above, the carbon coated fiber of the present invention has high strength, is difficult to break, and has excellent environmental resistance. Therefore, the present invention can be very effectively applied to the field of optical fibers for submarine cables.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of an example of a fiber coated with carbon according to the present invention, Fig. 2 is a Weibull plot of the tensile test results of a conventional fiber without a carbon coat, and Fig. 3 is a graph showing a carbon coat (film thickness 300). 2 is a chart showing the results of a tensile test of a fiber subjected to a test, similar to FIG. 2.

Claims (1)

[Claims] A carbon coated fiber comprising a carbon coating layer on the outer periphery of a quartz-based optical fiber, wherein the carbon coating layer has a thickness of 10 to 100 Å.