JPS6183651A - Production of fiber-reinforced optical fiber - Google Patents

Abstract

PURPOSE:In a method of producing fiber-reinforced optical fiber by one process in a hot dies, to obtain the titled high-quality optical fiber, by a continuous filament group treated with a resin containing inorganic fine particles. CONSTITUTION:Reinforcing filaments (e.g., glass fiber, or polyamide fiber) are passed through a resin containing about 20wt% inorganic fine particles (e.g., calcium carbonate or glass having about <=10mu particle diameter), so that the resin composition is bonded to the filaments. The filament group coated with the resin composition and optical fiber are introduced into a hot die, the surface of optical fiber is coated with the resin composition, and the resin is cured, to produce fiber-reinforced optical fiber. By this method, optical fiber preventing microscopic bend can be prepared without causing tensile damage.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to an improvement in the manufacturing method of fiber reinforced optical fibers.

Prior Art and Problems It is well known that optical fibers, which are the bare wires of optical transmission cables, or bundles of optical fibers, are coated with a glass fiber reinforced resin layer as a reinforcing layer. , the present applicant has already proposed a method of forming a fiber-reinforced resin layer on the optical fiber by passing the optical fiber through a die together with (continuous glass fJ!, Yft) impregnated with sealant, and curing the resin within the die. did.

In this method, only molding is performed using a die, and then the resin is hardened by passing it through a heating furnace (Japanese Patent Publication No. 56-76
Compared to Publication No. 1), for example, it has the advantage of preventing uneven thickness of the coating and is easy to tear, but it requires a large amount of tension to pull out the die in order to harden the resin in the die, and the mechanical strength of the optical fiber is low. Taking this into consideration, this is a problem.

Incidentally, depending on the type of curable resin, curing shrinkage may occur, and curing shrinkage has conventionally been treated as a negative factor in the curing and molding of the resin. However, if the resin is curing and shrinking in the die in the die pultrusion process described above, the curing shrinkage will act to prevent adhesion between the inner surface of the die and the cured resin, and the cured coating layer and the die will be affected by the curing shrinkage. Release the restraint between the inner world,
Since it becomes easy to slide between them, it is advantageous in reducing the above-mentioned drawing tension. However, as the coating layer hardens and shrinks, stress acts on the outer peripheral surface of the optical fiber, and especially when the optical fiber is a bundled wire, complex stress is generated in the optical fiber strands, which causes micro-bending. , there is concern that the transmission characteristics of optical fibers will deteriorate.

As described above, in the method for manufacturing fiber-reinforced optical fibers using the die pultrusion curing method, curing and shrinkage of the resin within the die has an advantageous effect on reducing the drawing force, but has a disadvantageous effect on the microbending of the optical fiber.

OBJECTS OF THE INVENTION An object of the present invention is to add inorganic fine particles to the above-mentioned curable resin and adjust its curing shrinkage rate in order to reconcile these contradictory matters.

Structure of the Invention The method for manufacturing a fiber-reinforced optical fiber according to the present invention includes forming a resin-impregnated fiber layer by passing an optical fiber through a die together with a group of continuous fibers impregnated with a resin to which inorganic fine particles are added, and curing the resin in the die. This method is characterized by curing while shrinking.

Description of Examples In the present invention, the continuous fiber group includes glass fiber, carbon fiber, or polyamide fiber (single fiber diameter 5 to 25μ).
can be used. As the resin, thermosetting resins such as polyester unsaturated resins and Epoquine resins can be used. One or more of calcium carbonate, talc, alumina, and glass fine powder can be used as the inorganic fine particles, and the particle size is as follows:
The thickness is preferably 10 μm or less so as not to disturb the arrangement of the reinforcing fibers (fiber diameter: 5 to 25 μm). The ratio of inorganic fine particles added to the resin is usually 20 weight Φ or less.

In the present invention, the optical fiber to be coated with the 1f1 fat-impregnated fiber layer is a single optical fiber (1@1 on the core).
(covered with a secondary cladding layer or a retention layer such as silicone resin), or by twisting several of these single wires and coating the outside with an outer skin material (silicone sliding, acrylic urethane resin).

To produce a fiber-reinforced optical fiber according to the present invention, a group of continuous fibers is passed through a resin bath containing inorganic fine particles,
The resin-impregnated fiber group and the optical fiber are collectively pultruded using a heating die, and the resin is heated and hardened within the die. When the resin hardens within the die, the resin hardens and shrinks, so the adhesive force between the inner surface of the die and the cured layer decreases, the binding force between them becomes smaller, and the force for pulling out the die can be reduced. The optical fiber is pressurized due to curing shrinkage of this resin, but since inorganic fine particles are added to the resin, the curing shrinkage rate can be reduced, so the pressure applied to the optical fiber is sufficiently reduced and the optical fiber is twisted. Even if it is a wire type, microbending can be well prevented.

Effects of the Invention Method V for producing a fiber-reinforced optical fiber according to the present invention This method is as described above, and the curing shrinkage rate of the resin-impregnated fiber layer is adjusted by adding inorganic fine particles, and the Since the amount of curing shrinkage is reduced and the pressure acting on the optical fiber is reduced, microbending of the optical fiber can be effectively prevented. However, since the resin is contracted to some extent during resin curing within the die, the die pulling force can be reduced despite the resin curing within the die, and tensile damage to the optical fiber can be reliably eliminated.

Claims (1)

[Claims] (1) Fiber reinforcement characterized by forming a resin-impregnated fiber layer by passing an optical fiber through a die together with a group of continuous fibers impregnated with a resin to which inorganic fine particles can be added, and curing the resin while curing and shrinking the resin in the die. Method of manufacturing optical fiber.