JPS58223637A - Preparation of core wire of optical fiber - Google Patents

Abstract

PURPOSE:To obtain a core fiber of an optical fiber having improved temperature dependence of transmission characteristics and mechanical characteristics, by wiping a reinforcing fiber with two rolls, impregnating, interstices of the reinforcing fibers with a resin, and positioning an element wire of an optical fiber at the center of the reinforcing fibers. CONSTITUTION:In a method for preparing a core optical fiber having the outer periphery coated with a thermosetting resin reinforced with reinforcing fibers, the reinforcing fibers 5 are led to the interior of an impregnation tank 6 by rolls (20A), and impregnated with the thermosetting resin. The reinforcing fibers 5 are then nipped by two rolls (20B) and wiped at the same time, further dipped in the thermosetting resin in the impregnation tank 6, nipped and wiped repeatedly by rolls (20B) and then fed to a preforming apparatus. In the initial resin impregnation section, the interstices between the reinforcing fibers are not fully impregnated with the thermosetting resin, but air is expelled from the interstices between the reinforcing fibers 5 by wiping with the two rolls (20B). Thus, the thermosetting resin on the surface of the fibers is forced to impregnate into the interstices between the reinforcing fibers 5.

Description

[Detailed description of the invention] An optical fiber coated with a thermosetting resin reinforced with amide fiber or carbon fiber, so-called F 1c p (fiber reinforced plastic) to improve the temperature dependence of transmission characteristics and mechanical properties. The present invention relates to a method for manufacturing a core wire.

As shown in FIG. 1, a conventional optical fiber core wire has a primary coating 2 and a buffer layer 6 on a fiber 1, and a thermoplastic resin such as nylon is coated thereon as a secondary coating layer 4. ing.

Although this M-shaped fiber has the advantage of being relatively easy to manufacture, the temperature dependence of the secondary coating plastic, whose linear expansion coefficient is ρ, is better than that of glass 4゛4F+.'' Since the transmission characteristic σ is large, it also has the drawbacks of large temperature dependence and weak resistance against bending side 1 (·°).

For this reason, it is impossible to use this core wire alone, and reinforcing materials such as tension members are required to use it as a cable or cord.

In order to solve these drawbacks of conventional optical fiber cores, it is known that it is very effective to use a thermosetting resin reinforced with aromatic polyamide fibers, carbon fibers, etc. as a secondary coating. It is being

The present invention provides such F i. There is a method that has been made to successfully manufacture a cored optical fiber coated with tp.

Normally, in order to manufacture a core wire coated with FRP as a secondary coating layer, a pultrusion method, which is the FTIP connection painting method, is employed.

These seven examples will be explained with reference to FIG.

Epoxy, unsaturated resin IJ to reinforcing fiber 5 such as carbon fiber
After being impregnated with the resin in a resin impregnating tank 6 filled with a thermosetting resin such as ester resin, the optical fine fiber wire 7 coated up to the buffer layer is supplied, and the r-prepared cedar equipment 8
The reinforcing fibers are located in the center. After that, the resin is heated in a heat curing furnace 9 to harden the resin, and then the drawing device 10
The material is then pulled out of the heat curing furnace and wound onto a bobbin by the winding device 11.

However, in this method, f' of the resin into the reinforcing fibers is
The resin can be cured by performing fl for 1 minute or by curing the resin in a heat curing oven.
Because of the need for ultra-thin fibers, the manufacturing speed is extremely low at around /m/min, making it extremely expensive compared to the conventional optical fiber core shown in Figure 1, and it is too expensive for practical use. There was l'ka. Regarding the curing of the resin, please refer to A) J11 The problem can be solved by simply extending the heat curing furnace to a sufficient length.
However, impregnating the reinforcing fibers with resin reduces the linear speed to 4-,
As the coating progresses, the resin does not penetrate into the fiber gaps sufficiently due to the air that exists in the fiber gaps, and the number of voids increases in the secondary coating layer, resulting in the formation of right-circular holes. It was difficult to maintain the fibers, and only good FRP coated optical fibers could be obtained.

The present invention achieves the above-mentioned method by impregnating the reinforcing fibers with the resin by squeezing the reinforcing fibers impregnated with the resin between two rolls. This solved the problem.

This will be explained with reference to FIG. Figure 3 shows resin impregnation tank 6.
This is an example in which reinforcing fibers 5 are impregnated with resin.

The reinforcing fibers are rolled using roll 2OA that guides the fibers in the same way as in the conventional method.
It is guided into an impregnating tank and immersed in resin in the tank. After that, two rolls 20J3 kg of fibers are sandwiched and squeezed at the same time, and then dipped in the resin in the tank by roll 2OA and transferred to roll 20J3 again. (11if supplied to the molding device. In section A where the original fibers are impregnated with resin, there is no resin in the gap between the fibers) or 2 rolls 20B and 4 rolls [1 As a result, the air in the fiber gaps is forced out, and the resin on the fiber surface is forcibly penetrated into the fiber gaps G.

In this example, the fibers are further immersed in G (a) in the resin in section B.
G
The resin is fed to the preforming and forming equipment in such a way that it is compressed into fibers.

The stiffening of the reinforcing fibers by kneading and rolling rolls is not limited to one repetition, but the number of repetitions can be selected as appropriate, and this rolling work is only performed outside the resin in the tJ tank. Instead, it can also be done by positioning it inside the resin. Also, the degree of ironing effect of the two rolls of yarn 11 is! This can be easily done by adjusting the interval between the rolls.

By this Jj method, the resin can be completely impregnated into the fiber, and voids in the secondary coating layer are eliminated, and a good optical fiber core wire that can be maintained at 100 yen can be efficiently processed.

In addition, this method can be carried out at a low cost, and is not only suitable for manufacturing optical fiber core wires, but also for the purpose of impregnating the reinforcing fibers with resin, holding them in a predetermined shape, and curing the resin. It is also useful for molding fiber-reinforced plastics.

The reinforcing fibers used in the present invention are aromatic polyamide fibers, carbon fibers, and glass fibers.

Alumina fibers, etc., or thermosetting resins such as epoxy, slightly saturated polyester, phenol, and Boliimi resin can be used as the resin.

Next, we will see a case where fiber stiffness is achieved using the two rolls of the i invention, and a case where fibers are made into resin in the conventional 1F 'fi 2i! f
The following table shows a comparison of the 'l' properties of optical fibers coated with Ii'' R and P using the method described above.

In this case, the ellipticity will be shown because if the resin has insufficient θ content, it will likely affect the retention of the perfect circular shape in the heat curing furnace.

(Margin below) 71・/ Ovality - Maximum diameter - Minimum diameter t1.2 Optical fiber core diameter (center diameter) /, Om-a
φ Optical fiber wire diameter 0. Since the optical fiber core wire produced by the manufacturing method of the present invention does not require a tension member when used as a cable or cord,
It fully demonstrates its effect.

[Brief explanation of the drawing]

Figure 11 is a cross-sectional view of the optical fiber core wire, Figure 2 is FR, P
FIG. 3 is an explanatory view of an example of the coloring method, and is an explanatory view of an example in which reinforcing fibers are impregnated with resin in a resin impregnation bath having ten disadvantages of the present invention. DESCRIPTION OF SYMBOLS 1...Fiber, 2...Primary coating, filter pants-γ layer, 4...Secondary coating layer, 5...
Reinforcement fiber, 6.Resin impregnation tank, 7..Optical fiber wire, 8.
... Preformed bag; a, 9... Heat curing furnace, 10...
・Extraction device, 11... Removal device, 2OA, 20B
···roll.

Claims (1)

[Claims] 1. When manufacturing an optical fiber core wire in which the outer periphery of the optical fiber is coated with a thermosetting resin reinforced with reinforcing fibers, the reinforcing fibers are sandwiched in a resin impregnating tank using at least the rolls of 2)). A method for manufacturing an optical fiber core wire, characterized in that the optical fiber string supplied is positioned at the center of the reinforcing fibers 11J after the resin is infiltrated into the gaps between reinforcing fibers by squeezing the reinforcing fibers while looking at the reinforcing fibers.