JPH03107904A - Manufacture of optical fiber - Google Patents

Abstract

PURPOSE:To obtain constant outside dimension by eliminating a fear for the sticking of foreign matters on the surface of a core material and preventing the running of an optical fiber due to its dead weight by co-extruding the core material and a clad material from a double concentric circular nozzle and soaking them in a solution, and applying a bridging processing while they are being soaked. CONSTITUTION:Both the core material 2 and the clad material 3 which covers the core material 2 are co-extruded from the double concentric circular nozzle 4, and also, they are soaked in the solution not giving an adverse effect on the core material 2 and the clad material 3, and the bridging processing is applied while they are being soaked in the solution. Therefore, the optical fiber 1 can be extruded at a state where the core material 2 is covered with the clad material 3. In such a manner, no foreign matters are stuck on the surface of a core, and the running of the optical fiber 1 due to its dead weight due to the reception of the floating force of the solution by the optical fiber 1 before bridging can be surely prevented from occurring, and the optical fiber with constant outside dimension and constant rubber shape elasticity can be stably manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing an optical fiber, and in particular to a method for manufacturing an optical fiber in which a core and a cladding covering the core are imparted with rubber-like elasticity by crosslinking. It is something.

[Prior art and problems to be solved] Conventionally, regarding the technology for manufacturing optical fibers having rubber-like elasticity, (
1) JP-A-61-259202, (2) JP-A-64-
The method described in No. 503 is known.

In the method described in (1) above, a concentric nozzle is used to coextrude the core material as an inner layer and the cladding material as an outer layer, and the coextruded material is irradiated with radiation such as an electron beam or ultraviolet rays, or heated. By crosslinking the fibers, an optical fiber with rubber-like elasticity was obtained.

However, in general, in the manufacturing process of optical fibers having rubber-like elasticity, there is a phenomenon in which the optical fiber before crosslinking is cast due to its own weight, so it is difficult to make the outer diameter dimension constant.

In the method (1) above, there is no mention of the problem of casting due to the weight of the optical fiber before crosslinking, and there is no mention of the problem of casting due to the weight of the optical fiber before crosslinking, and there is no mention of the problem of controlling the outer diameter dimension of the resulting optical fiber having rubber-like elasticity. There is no mention of that.

In addition, in the method described in (2) above, the core material is extruded from a nozzle and cross-linked, and then covered with the cladding material, so the outer diameter of the optical fiber can be kept constant to some extent, but the manufacturing process The process becomes complicated, and there is a concern that foreign matter may adhere to the surface of the core material during the manufacturing process.

The present invention solves the problems of the conventional ones as described above, and is simple, eliminates the fear of foreign matter adhering to the surface of the core material, and prevents the optical fiber from being cast due to its own weight. It is an object of the present invention to provide a method for manufacturing an optical fiber having a constant outer diameter and rubber-like elasticity.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a method for manufacturing an optical fiber in which a core and a cladding covering the core are imparted with rubber-like elasticity by crosslinking, comprising: a core material for forming the core; The cladding material for forming the cladding is coextruded from a double concentric nozzle, and the coextruded material is immersed in a liquid that does not have a negative effect on the core material and the cladding material, and during this immersion, the core material is It is preferable that the material coextruded from the double concentric nozzle is immersed in the liquid at the same time as the coextrusion, and the liquid is aliphatic The aliphatic hydrocarbon organic solvent may be n-hexane.

[Effect]

By adopting the above-mentioned means, the present invention allows the core material and the cladding material to be co-extruded from a double concentric nozzle, and is immersed in a liquid, and cross-linked during the immersion. The core material is extruded with its surface covered with a cladding material in advance, ensuring that no foreign matter adheres to the surface of the core material, and that the optical fiber before crosslinking receives the buoyancy of the liquid and is cast under its own weight. This results in an optical fiber having a constant outer diameter.

[Specific structure of the invention] The present invention will be explained in detail below.

The drawings show an embodiment of the present invention, and FIG. 1 shows a schematic diagram of an apparatus for carrying out the method of manufacturing an optical fiber according to the present invention.

That is, the apparatus used in the optical fiber manufacturing method of the present invention includes an extrusion die 5 equipped with a double concentric nozzle 4 and a liquid tank 7 containing a liquid 6 that does not adversely affect the core material 2 and the cladding material 3. and a bridging member 8 provided outside the liquid tank 7.

Further, a coating agent tank 1O containing a coating agent 9 for coating the outer periphery of the crosslinked optical fiber 1, a heating furnace 11 for drying the coating agent, a winding roller 12 for winding the obtained optical fiber 1, and a It is provided with auxiliary rollers 13 that serve as guides when the fiber I moves between them.

Here, the extrusion die 5 has its double concentric nozzle 4
The distal end portion thereof is placed in a state of being immersed in the liquid 6 of the liquid tank 7.

To manufacture the optical fiber 1 using the above-mentioned apparatus, first, the core material 2 is loaded into the inner nozzle of the double concentric nozzle 4 of the extrusion die 5, and the cladding material 3 is loaded into the outer nozzle.

Then, in advance, the extrusion die 5 is activated and the core material 2 coated with the cladding material 3 is set to be wound up by the winding roller 12 through the liquid tank 7, the coating agent tank 1o, and the heating furnace 11. do.

Next, the extrusion speed of the extrusion die 5 or the winding speed of the winding roller is set to predetermined conditions, and the optical fiber 1 is continuously manufactured.

That is, the core material 2 coated with the clad material 3 is coextruded from the extrusion die 5 into the liquid tank 7, and the liquid 6 is
Soak in.

Then, while the coextruded optical fiber 1 before crosslinking is immersed in the liquid 6, a crosslinking process is performed using the crosslinking member 8 outside the liquid tank 7.

Then, the optical fiber 1 that has been crosslinked in the liquid tank 7 is sent to the outside of the liquid tank 7 via the auxiliary roller 13 in the liquid tank 7, and the coating agent 9 is passed through the auxiliary roller 13.13. After coating the outer periphery with coating agent 9, it is dried in a heating furnace 11 for drying, and is wound up with a winding roller 12 to continuously form a layer of light having rubber-like elasticity. A fiber 1 can be manufactured.

Here, the liquid 6 in which the optical fiber 1 is immersed may be any liquid as long as it does not have an adverse effect of dissolving the core material 2 and the cladding material 3, but it has good volatility and a specific gravity. It is preferably smaller than the optical fiber 1, and when a radiation irradiation device is used as the crosslinking member 8, it is preferably a material with good radiation transmittance; for example, n-hexane, cyclohexane, isooctane, etc. Typical examples include aliphatic hydrocarbon organic solvents such as

The core material 2 of the optical fiber 1 may be any rubber material as long as it has excellent transparency and becomes a rubber-like elastic body when crosslinked by heating, such as acrylic rubber,
Examples include polymeric materials such as silicone rubber to which an appropriate amount of a crosslinking agent is added.

The cladding material 3 of the optical fiber 1 has excellent transparency, has a lower refractive index than the core material 2, and can be easily crosslinked (in a short time) by heating or radiation (ultraviolet rays, electron beams, etc.) to form a rubber-like elastic material. For example, a copolymer of octafluoropentyl acrylate (hereinafter referred to as 0FPA) and dicyclopentenyl acrylate (hereinafter referred to as DCPA), tetrafluoropropyl acrylate. (Hereinafter referred to as TFP
A) and 2-hydroxyethyl acrylate (abbreviated as A) and 2-hydroxyethyl acrylate (abbreviated as A)
Examples include copolymers with HEA (hereinafter abbreviated as HEA), dimethyl silicone, and polymeric materials in which appropriate amounts of photopolymerization initiators, crosslinking aids, and the like are added.

As the bridging member 8, a radiation irradiation device such as ultraviolet rays or electronic cotton, a heating furnace, or the like can be used.

The time that the optical fiber 1 coextruded into the liquid tank 7 is immersed in the liquid 6 is the same as that of the core material 2 and the cladding material 3.
are the times at which the crosslinking is completed, and appropriate times are selected depending on the materials of the core material 2 and the cladding material 3, the conditions for crosslinking by the crosslinking member 8, and the like.

In the above embodiment, the core material 2 and cladding material 3 co-extruded from the double concentric nozzle 4 were immersed in the liquid 6 at the same time as extrusion, but the tip of the double concentric nozzle 4 and the liquid If there is a gap between the liquid 6 in the tank 7 and this gap is a distance (for example, 10 cm or less) that allows almost negligible casting due to its own weight when the optical fiber 1 before crosslinking passes through it at a normal extrusion speed, Almost the same effect as the previous embodiment can be achieved and is within the scope of the present invention.

Therefore, in the optical fiber manufacturing method of the present invention, the core material 2 and the cladding material 3 are inserted into the double concentric nozzle 4.
Since the core material 2 is coextruded from the cladding 3 and the crosslinking treatment is performed in the liquid 6, the optical fiber 1 before crosslinking is extruded while the core material 2 is covered with the cladding 3, thereby preventing foreign matter from forming on the surface of the core. It will not stick.

Furthermore, the optical fiber 1 before crosslinking is subjected to the buoyancy of the liquid 6 in the liquid 6, thereby reliably preventing the optical fiber 1 from being cast due to its own weight, thereby making it possible to obtain the optical fiber 1 with a constant outer diameter dimension. It is something.

Furthermore, when an ultraviolet irradiation device is used as the crosslinking member 8, the crosslinking treatment is performed on -111Q in an inert gas atmosphere such as nitrogen gas or argon because oxygen inhibits the crosslinking reaction. In this case, there is no need for that.

In addition, in the above embodiment, the core material 2 is
Although the core material 2 and the cladding material 3 are co-extruded, they may be allowed to flow down due to their own weight (also, the extrusion direction of the double concentric nozzle 4 may be extruded in a direction different from the direction of gravity under a predetermined pressure). You can.

Hereinafter, the present invention will be explained in more detail using experimental examples.

Experimental example-1 The following experiment was conducted using the apparatus shown in FIG.

As the core material 2, a copolymer of ethyl acrylate (hereinafter abbreviated as EA) and HEA (mole ratio 96:4) to which a crosslinking material was added was used, and as the cladding material 3,
Copolymer of 0FPA and DCPA (molar ratio 90:10)
A polymerization initiator and a crosslinking aid were added to the above.

The above core material 2 and cladding material 3 were each loaded into an extrusion die 5 equipped with a double concentric nozzle 4, and 50C11
n-hexane (specific gravity -
0.68, boiling point = 69''C) into a liquid bath 7.

Further, an ultraviolet irradiation device is used as the bridging member 8, and the temperature of n-hexane, which is the liquid 6 in the liquid tank 7, is set to about 60°C by the bridging member 8, and the temperature is set to about 60°C. The crosslinking time of the optical fiber 1 was about 1 minute.

The double concentric nozzle 4 used had an inner diameter of 0.6 m and an outer diameter of 1.1511 m.

The specific gravity of the obtained optical fiber 1 was 1.37.

Then, at the stage when the liquid tank 7 is taken out, the optical fiber l
When we measured the outer diameter of
Only the tumor had become thinner.

Moreover, the transmission loss of the obtained optical fiber 1 was 86%/m.

Experimental Example-2 In the above Experimental Example-1, the cladding material 3 was 0FPA.
The experiment was carried out under the same conditions as in Experimental Example 1, except that the crosslinking member 8 was replaced with a heating furnace.

When the outer diameter dimension of the obtained optical fiber 1 was measured, it was found that 1
The variation in the outer diameter dimension over the length of m was that the root portion was narrower by 0.06 m5 than the tip portion, and the transmission loss was 86%/m.

Comparative Experimental Example-1 In the above-mentioned Experimental Example-1, the same procedure as Experimental Example-1 was carried out except that the liquid tank 7 was not used.

When the outer diameter dimension of the obtained optical fiber 1 was measured, it was found that 1
With respect to the length of m, the variation in the outer diameter was 0.16 mm thinner at the root than at the tip, and the transmission loss was 70%/m.

As is clear from the above results, in the method according to the present invention, compared to the comparative experiment, the optical fiber l is prevented from being cast due to its own weight, has a constant outer diameter dimension, and has a lower transmission loss. It can be seen that an optical fiber l with a small decrease in .

〔Effect of the invention〕

As described above, the present invention involves co-extruding a core material and a cladding material covering the core material through a double concentric nozzle, immersing the core material and the cladding material in a liquid that does not have a negative effect, and cross-linking them during this immersion. Because the treatment is applied, the optical fiber is extruded with the core material covered with the cladding material, preventing foreign matter from adhering to the surface of the core, and the optical fiber before crosslinking receives the buoyancy of the liquid, allowing light to flow out. This method has excellent effects such as reliably preventing the fiber from being cast due to its own weight and stably producing an optical fiber having rubber-like elasticity and a constant outer diameter.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram illustrating a method of manufacturing an optical fiber according to the present invention. ■... Optical fiber 2... Core material 3... Clad material 4... Double concentric nozzle 5... Extrusion die 6... ...Liquid 7...Liquid tank 8...Bridging member 9...Coating agent 10...Coating agent tank 11...Heating Furnace 12... Winding roller 13... Auxiliary roller procedural amendment (voluntary) Attachment 1.1 Relevant Address Name (Name) 4. Agent 5. Date of amendment order 6. Subject of amendment March 2, 1990. 1999 Sacrifice No. 247653 The manufacturing method of optical fiber is disclosed in Tokyo. NOK Co., Ltd. 1-12-15 Shiba Daimon 1-12-15 (43B), Minato-ku, Tokyo 8-7-18 Akasaka, Minato-ku, Tokyo 107 1a03 (5474) 8801 "Claims J and Scope of Claims in the Specification of Own Invention" (1) A method for manufacturing an optical fiber in which a core and a cladding covering the core are imparted with rubber-like elasticity by crosslinking, the method comprising: a core material (2) for forming the core;
The cladding material (3) for forming the cladding is coextruded from a double concentric nozzle (4), and the coextruded material is combined with the Yuerin (2) and the cladding material (
3) A method for manufacturing an optical fiber, characterized in that the core material (2) and the cladding material (3) are crosslinked during immersion in a liquid (6) that does not have an adverse effect on the fiber. (2) The method for manufacturing an optical fiber according to claim 1, wherein the coextrusion from the double concentric nozzle (4) is immersed in the liquid (6) at the same time as the coextrusion. (3) The liquid (6) is an aliphatic hydrocarbon organic solution (
4) The method for manufacturing an optical fiber according to claim 1, wherein the optical fiber is a medium. 3. The method for manufacturing an optical fiber according to claim 2, wherein the aliphatic hydrocarbon organic solvent is n-hexane. −2(

Claims (4)

[Claims] (1) A method for manufacturing an optical fiber in which a core and a cladding covering the core are imparted with rubber-like elasticity by crosslinking, the method comprising: a core material (2) for forming the core; and a method for forming the cladding. The core material (2) and the cladding material (3) are co-extruded from a double concentric nozzle (4), and the co-extruded material is combined with the core material (2) and the cladding material (3).
A method for manufacturing an optical fiber, characterized in that the core material (2) and the cladding material (3) are crosslinked during immersion in a liquid (6) that does not have an adverse effect on the fiber. (2) The method for manufacturing an optical fiber according to claim 1, wherein the coextrusion from the double concentric nozzle (4) is immersed in the liquid (6) at the same time as the coextrusion. (3) The method for manufacturing an optical fiber according to claim 1, wherein the liquid (6) is an aliphatic hydrocarbon organic solvent. (4) The method for manufacturing an optical fiber according to claim 2, wherein the aliphatic hydrocarbon organic solvent is n-hexane.