JPS60171250A - Method for coating metal to optical fiber - Google Patents

Abstract

PURPOSE:To produce a metal-coated optical fiber which is free from fracture in the stage of producing and installing a cable and is prevented against intrusion of moisture for a long period by passing the fiber applied with a resin coating through a molten metal under specific conditions. CONSTITUTION:A resin-coated optical fiber (made of silica glass) 1 which is led out from an upper bobbin 10 and is traveled vertically so as to be taken up on a lower bobbin 10 is passed through a nozzle 11 (a symbol 11a is an aperture) to which a molten metal 3a is supplied through a spout 12 communicating with a crucible 13, thereby depositing and solidifying the molten metal 3a on the surface and forming further a metallic coating on the resin coating. A high polymer compd. having >=140 deg.C softening point is used as the resin to coat the fiber and on the other hand tin or a tin-lead alloy (about 100-240 deg.C melting temp.) having the melting temp. lower than the softening temp. of said resin is used as the metal. Said metal is used after the metal is melted to the temp. slightly higher than the melting temp. thereof.

Description

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

Optical fibers used in communication cables, etc. are resistant to bending external forces during the manufacturing or installation of the cable.
Some kind of protective measures are required to prevent breakage accidents and to prevent moisture from entering during long-term use. Conventionally, this problem has been solved by coating the fiber surface with a polymeric compound coating, but this problem remains unsatisfactory.

As a solution to this dissatisfaction, a method was proposed in which the surface of the fiber was coated with a metal film. Although this was an improvement in terms of breakage accidents, the heat resistance of the organic polymer coating the fiber was not at all satisfactory. Not getting attention. Further, the metal covered with the coating layer merely exhibits a low alloy metal. In general, low alloy alloys are made by adding bismuth to tin, and many have a melting point of 100 degrees or less, and the inclusion of bismuth inhibits ductility. This ductility problem imposes new restrictions on the conditions during cable manufacturing and installation, and is not a preferred manufacturing method.

The present invention proposes a method for manufacturing metal-coated optical fibers that solves the problems of soft soil at once, eliminates breakage accidents, and allows cable manufacturing and installation to be carried out under normal conditions. The basic structure is that the fiber surface is coated with a polymer compound coating with a heat softening temperature of 140 degrees or higher, and the fiber is coated with a metal whose melting temperature is slightly lower than the heat softening temperature of the coating. The metal coating is solidified on the surface of the polymer compound coating by vertically passing through a nozzle filled with the metal in a molten state at a high temperature.

More specifically, the molten metal in the present invention is melted and filled into the nozzle at a temperature slightly higher than its melting temperature, and at the same time as the fiber passing through the nozzle enters the nozzle, the metal is coated on the surface of the coating. The coating is formed by utilizing the phenomenon of cooling, solidifying and adhering with a fiber whose temperature is lower than that of the molten metal, and the molten metal is mainly composed of ductile tin or tin and lead. It is necessary and desirable that the passage speed through the nozzle be extremely high. Further, passing the fiber vertically through the molten metal is necessary in order to form a concentric metal coating on the curved surface of the fiber. Furthermore, the manufacturing method of the present invention includes a method of manufacturing by a continuous continuous process starting from spinning a silica-based glass fiber.

An example of implementation of the present invention will be described below.

The drawings schematically show the apparatus used in the method of the invention.

One of the bobbins (10) (10) has a heat softening temperature of 140
A silica-based glass fiber (1) coated with a coating (2) of 100% or higher is wound around the nozzle (11).
It is used for winding up the fiber (1) which passes through the coating (2) and is coated with a metal coating (3) on the surface thereof.

The nozzle (11) has upper and lower openings (11a) (11a) through which the fiber (1) passes vertically, and the inside thereof is filled with molten metal (3a), which passes through the nozzle. A metal film (3) is coated on the surface of the fiber (1) to be coated with Fl (2). In addition, the nozzle (11) has a spout (
12) communicates with a crucible (13), which is made of a metal having a melting temperature lower than the thermal softening temperature of the coating (2), specifically, for example, mainly containing tin or tin and lead. A ductile material is melted at a temperature slightly higher than its melting temperature (100 to 240 degrees), and the molten metal (3a) at the same temperature is passed through the nozzle (1
1). Frontage (Il) of nozzle (11)
a) (11a) is a non-1114 gas chamber (14)
This non-oxidizing gas chamber (14) is surrounded by a nozzle (11) filled with molten metal (3a) with non-oxidizing gas (G) fed from the air inlet (14a) (14a). )
This prevents oxidation of the molten metal (3a) in the opening (Ila) (11a).

As a result, the fiber (1) pulled out from the bobbin (10) and coated with the polymer coating (2) is guided to the guide roll (15) (15) and is guided to the nozzle (11).
) is passed vertically at high speed, and during the passage, the manufactured fiber (1) is coated with a metal coating (3) and wound onto a bobbin (10). The coating is formed in two layers, the inner and outer layers, consisting of a flexible polymeric compound coating (2) and a ductile outer metal coating (3), which prevents breakage, has excellent ductility, and prevents moisture from entering. Ta.

Therefore, the present invention has the following advantages.

(2) A highly versatile metal-coated fiber that is free from breakage and has good ductility and flexibility can be manufactured without imposing new restrictions on manufacturing conditions.

■ Since the metal coating is solidified by passing it vertically through a nozzle filled with molten metal, the metal coating can be formed concentrically, making it possible to mass-produce fibers with uniform metal coating around the circumference. This is a manufacturing method suitable for

[Brief explanation of the drawing]

Figure 1 shows the process in which a fiber coated with a heat-resistant polymer compound coating is pulled out from a bobbin, passes vertically through a nozzle filled with molten metal, and a metal coating is formed on the coated surface. Schematic diagram shown. FIG. 2 is a cross-sectional view of a metallized fiber. In the figure, (1) is the fiber (2) is the polymer compound coating (3) is the metal coating (3a) is the molten metal (11) is the nozzle Patent applicant: Kokoku Steel Wire & Cable Co., Ltd. Figure 2

Claims (1)

[Claims] ■ The fiber surface is coated with a coating made of a polymer compound having a heat softening temperature of 140 degrees or higher.1. This fiber is passed vertically through a nozzle filled with a metal whose melting temperature is lower than the thermal softening temperature of the coating at a temperature slightly higher than the melting temperature of the metal, and the above-mentioned fiber is applied to the surface of the polymer compound coating. A method for coating an optical fiber with metal, characterized by solidifying and forming a metal coating. (2) The method of metal coating an optical fiber according to claim 1, wherein the fiber is made of silica-based glass. (2) Any optical fiber metal according to claim 1 or 2, wherein the metal is a ductile material mainly consisting of tin or tin and lead, and has a melting temperature of 100 to 240 degrees. Coating method.