JPH0675125B2 - Manufacturing method for plastic optical fiber - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a plastic optical fiber having a low optical transmission loss.

[Prior Art] Plastic optical fibers are frequently used because of their advantages such as flexibility.

FIG. 2 is a schematic diagram showing a conventional plastic optical fiber manufacturing facility. This production facility includes a distillation column 11 'for purifying the monomer, a mixer 12' for mixing the monomer with a catalyst, a polymerization reactor 13 'for polymerizing the monomer, and a devolatilizer.
Have 14. The devolatilizer 14 is a screw extruder, which removes the volatilizers that are harmful to fiber formation and fiberizes the polymer. The polymer is supplied from the inlet 21 of the screw extruder 14, the volatile matter in the polymer is removed by the decompression line 22 in the screw extruder, and then the polymer is transferred to form a fiber. The fiberized polymer emerges from outlet 23.

However, this manufacturing facility cannot manufacture a plastic optical fiber having excellent optical transmission loss. The sliding of the screw and extruder cylinder in the devolatilizer removes the metal (usually transition metal, eg, iron) particles that make them up into the polymer, causing scattering and absorption losses. is there.

[Structure of the Invention] The gist of the present invention is to remove volatiles from a polymer by extruding the core polymer from a perforated plate into a reduced pressure guide in a strand shape, forming a core by fiberizing the polymer, and then forming a clad. A plastic optical fiber manufacturing method is characterized in that it is formed around a core. The production method of the present invention is characterized in that a volatile matter is removed from a polymer for a plastic optical fiber by extruding the polymer from a porous plate into a decompression chamber in a strand shape.

In the method for producing a plastic optical fiber of the present invention, the removal of volatiles from the polymer is mainly used for the core-forming polymer, but it may also be used for the clad-forming polymer.

The manufacturing method of the present invention will be described below with reference to the accompanying drawings. The manufacturing method of the present invention is not limited to the following modes.

FIG. 1 is a schematic view of a plastic optical fiber manufacturing facility showing one embodiment of the manufacturing method of the present invention. This manufacturing facility has a distillation column 11, a mixer 12, a polymerization reactor 13 and a volatile matter removing device 19. A distillation column 11 excluding the volatile matter removal device 10,
The mixer 12 and the polymerization reactor 13 may be the same as those used in the conventional manufacturing facility, or may not be as shown in the accompanying drawings, and may be any device capable of supplying the polymer to the device 10. The volatile matter removal device 10 has a perforated plate 3 and a decompression line 2. The pore diameter of the perforated plate 3 is 0.5 to 3.0 mm
Is preferred. This manufacturing facility is preferably a closed system in which the leak in the joint is 0.5 lusec or less. The process in the volatile matter removing device 10 in the production of the plastic optical fiber will be described below.

The polymer containing volatile matter is transferred by gas pressure and supplied from the inlet 1 to the volatile matter removing apparatus 10. The volatile matter removal device 10 is kept in a reduced pressure state by the reduced pressure line 2. The polymer is
By passing through the porous plate 3, the strands 4 as shown in FIG. 1 are extruded into the decompression container, and the volatile substances in the polymer are removed. The polymer transfer path and the interior of the device 10 are heated to a high temperature, e.g.
It is preferably maintained at 0 to 300 ° C. The polymer is temporarily stored in the lower part of the apparatus 10, the polymer is extruded from the outlet 5 by gas pressure, and the polymer is fiberized (if necessary at the outlet 5) to form a core.

A cladding is then formed around the core emerging from the device 10. The clad can be formed by a method such as melt coating or solution coating.

[Advantages of the Invention] When the production method of the present invention is used, a plastic optical fiber having excellent optical transmission loss is produced because there is no sliding of metal to metal and the metal is not mixed in the polymer. This is because the polymer is transferred by gas pressure and the surface area of the polymer is increased by passing the polymer through the porous plate in order to improve the devolatilization effect.

[Examples] Examples and comparative examples are shown below.

Example 1 Using the equipment shown in FIG. 1, a plastic optical fiber having a core of polymethylmethacrylate and a cladding of fluorine-containing methylmethacrylate with a core diameter of 0.985 mm, a cladding thickness of 0.015 mm and a fiber outer diameter of 1.015 mm was manufactured. did. The leak at the joint of the manufacturing equipment was 0.5 lusec. Azoisobutyronitrile (0.1% by weight based on the monomer) was used as a polymerization initiator. In the volatile matter removing device 10, the perforated plate 3 has a pore diameter of 2.0 mm and an internal pressure of 1
It was 0 mmHg, and the temperature of the polymer transfer path and the volatile matter removal device 10 was kept at 200 ° C.

The optical transmission loss of the obtained plastic optical fiber is 56
It was 70 dB / km at 8 nm light.

Comparative Example 1 A similar plastic optical fiber was manufactured by repeating Example 1 except that the conventional equipment shown in FIG. 2 was used. The optical transmission loss of the obtained plastic optical fiber has a wavelength of 568n.
It was 100 dB / km at m light.

[Brief description of drawings]

FIG. 1 is a schematic view of a plastic optical fiber manufacturing facility showing one embodiment of the manufacturing method of the present invention, and FIG. 2 is a schematic view of a conventional plastic optical fiber manufacturing facility. 1,21 ... inlet, 2,22 ... decompression line, 3 ... perforated plate, 4 ... strand, 5,23 ... outlet, 10,14 ... volatile matter removing device, 11,11 '
... Distillation column, 12,12 '... Mixer, 13,13' ... Polymerization reactor.

Claims (1)

[Claims] 1. A core polymer is extruded from a porous plate into a vacuum chamber in a strand shape to remove volatiles from the polymer, and the polymer is made into fibers to form a core, and then a clad is formed around the core. A method for manufacturing a plastic optical fiber, characterized in that: