JPS6028773B2 - Method of manufacturing optical fiber cable - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method of manufacturing an optical fiber cable.

Conventionally, attempts have been made to add fibers with high tensile strength to optical fibers to form a tension member, and to bundle them together with a protective covering or sheath of thermoplastic plastic, but this method has the following disadvantages: was there.

(1) The heat generated when extruding the thermoplastic sheath may deform the plastic coating previously applied to the optical fiber.

■ When the thermoplastic plastic sheath cools and contracts, the fibers with high tensile strength that serve as tension members are wrapped around the sheath and contracted, resulting in bending and no longer functioning as a tension member.

[3' The adhesion between the thermoplastic plastic sheath and the high tensile strength fibers that serve as tension members is poor and gaps are likely to occur, resulting in slippage between the optical fiber and sheath, causing the optical fiber to undulate and transmit data. Losses may increase.

In addition, as a structure without a sheath, a structure in which thin glass fibers are vertically attached to the outer periphery of an optical fiber coated with plastic and a reinforcing layer is formed using epoxy resin or polyester resin as a bonding material is disclosed in Tokkoku Sho 48-43642. It is stated in the official gazette.

However, with this type of structure, the reinforcing layer is made of epoxy resin or polyester resin, making the entire structure extremely hard and losing maneuverability, making it difficult to use for optical fiber cords that require flexibility. The drawback was that it couldn't be done.
SUMMARY OF THE INVENTION In view of the above circumstances, it is an object of the present invention to provide a method for manufacturing an optical fiber cable that can eliminate or alleviate all of the above drawbacks.

The method of the present invention will be specifically explained with reference to the drawings showing one embodiment.

In FIG. 1, 1 is an optical fiber coated with plastic.

First, a plurality of high tensile strength fibers 2 are added to the optical fiber so as to surround it.

Second, this composite is passed through liquid silicone rubber 3 to impregnate the fibers 2 with the liquid silicone rubber 3.

Third, the composite containing liquid silicone rubber 3 is passed through a die 4 to shape the composite.

Furthermore, fourthly, the liquid silicone rubber 3 contained in the composite is solidified.

5 is an electric furnace.

Fifth, they are then covered with a thermoplastic sheath such as nylon (polyamide resin). 6 is an extruder.

FIG. 2 shows the structure of the optical fiber cable manufactured in this manner.

In FIG. 2, 21 is an optical fiber coated with plastic, and 23 is silicone rubber, in which a plurality of high tensile strength fibers 22 are embedded.

If the outermost layer is made of only silicone rubber, it will be weak against mechanical stress and compression, so a thermoplastic plastic sheath 26 is provided. A suitable material for the fiber 22 having high tensile strength is aromatic polyamide, and for the sheath 26, in addition to the above-mentioned nylon, polyethylene, polyvinyl chloride, etc. are suitable.

According to the present invention, the following remarkable effects are achieved.

'1} Even when a thermoplastic sheath is provided by extrusion, the sheath does not come into direct contact with the plastic coating previously applied to the optical fiber, so the plastic coating does not deform.

■ Liquid silicone rubber is easy to manufacture because it blends well with fibers such as aromatic polyamide. {31 Since the amount of shrinkage when silicone rubber hardens is extremely small, small bends hardly occur in fibers with high tensile strength. ■ Even if fibers with high tensile strength are bent, the fibers still function as tension members when embedded in silicone rubber.

'5' Silicone rubber has good adhesion to the thermoplastic plastic sheath and the plastic coating of the optical fiber, so it is difficult to slip between the optical fiber and the sheath, causing the optical fiber to undulate within the sheath and causing transmission loss. There is no such thing as an increase in

[6' By using silicone rubber without using epoxy resin or the like, it is possible to protect the optical fiber due to its elasticity, and because it has good maneuverability, it can be used for optical fiber cords, etc.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention, and FIG. 2 is a cross-sectional explanatory diagram showing an example of an optical fiber cable manufactured by the method of the present invention. 1, 21; plastic-coated optical fiber, 2,
22: High tensile strength fiber, 3: Liquid silicone rubber, 4;
Dice, 26; thermoplastic sheath. Said two spears! Figure 1

Claims (1)

[Claims] 1. In a method of manufacturing an optical fiber cable in which a fiber with high tensile strength is attached to an optical fiber and a sheath is applied, a plurality of fibers with high tensile strength are attached to an optical fiber coated with plastic so as to surround the optical fiber, and liquid silicone rubber is added to the optical fiber to surround the optical fiber. An optical fiber characterized in that liquid silicone rubber is passed through the fibers to be impregnated between the fibers, the liquid silicone rubber is shaped by passing through a die, the liquid silicone rubber is solidified, and then a thermoplastic plastic sheath is applied thereto. Cable manufacturing method.