JPH11174242A - Plastic optical fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively provide a plastic optical fiber which has a desired outside diameter and is small in transmission loss. SOLUTION: This plastic optical fiber is constituted by integrating transparent plastic to the surface of the plastic optical fiber of <=90 deg.C in the glass transition temp. of part or the whole of the component materials of a light transparent part. The transparent plastic has at least nature to prevent the deformation of the plastic optical fiber even at the temp. exceeding the thermal deformation temp. of the outermost layer of the fiber after the integration to the plastic optical fiber. On the other hand, the transparent plastic has the nature to allow molding thereof at the temp. below the thermal deformation temp. of the outermost layer of the plastic optical fiber before integration to the plastic optical fiber. The transparent plastic preferably has the nature that the plastic is cured by a polymn. reaction. In addition, the transparent plastic has the nature that the plastic is cured by a crosslinking reaction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic optical fiber of a multimode refractive index distribution type having a transparent plastic integrated on its surface, and more particularly to a plastic optical fiber having a desired outer diameter.
The present invention also relates to a plastic optical fiber having a small transmission loss.

[0002]

2. Description of the Related Art A plastic optical fiber in which both a core and a clad are made of a plastic material has excellent flexibility as compared with a silica-based optical fiber, and has a large diameter so that end face processing and connection processing are easy. In recent years, various applications for optical signal media such as LAN and ISDN have been studied because of their lower cost. Among these, for example, a multi-mode refractive index distribution type plastic optical fiber having a refractive index distribution such that the refractive index gradually decreases from the center of the core as disclosed in Japanese Patent Application Laid-Open No. 5-241036 (hereinafter, referred to as "hereinafter"). , [Abbreviated as “GI-type plastic optical fiber”) is regarded as important as an optical signal medium in the concept of a next-generation communication network because of its large transmission capacity.

As a method of manufacturing this type of GI-type plastic optical fiber, there is, for example, a method disclosed in Japanese Patent Application Laid-Open No. H5-241036 or International Publication No. WO94 / 04949. First, JP-A-5-241036 discloses that after a core liquid is poured into a cylindrical polymerization vessel made of a clad material, the polymerization reaction is performed from the periphery while rotating the polymerization vessel at a uniform speed with a rotating device or the like. A method for producing a plastic optical fiber by producing a plastic optical fiber preform by heating the preform is described. Further, International Publication No. WO94 / 04949 discloses a method of obtaining a plastic optical fiber by using a multi-core nozzle and extruding materials having different refractive indexes from each nozzle.

Incidentally, plastic optical fibers obtained by these manufacturing methods are generally provided with polyethylene or polyvinyl chloride on the surface thereof for the purpose of preventing the intrusion of disturbance light and the damage by mechanical external force. A protective layer made of a thermoplastic resin is formed by extrusion coating or the like, is formed into a cable, and is provided for practical use.

[0005]

However, the above-mentioned conventional plastic optical fiber has the following problems. First, all conventional plastic optical fibers are applied with a certain amount of tension during heating wire drawing or extrusion molding in the manufacturing process, and are shaped while being pulled in the length direction. In this case, shrinkage occurs in the length direction due to the influence of the heat of the resin or the pressure of the molten resin, which causes a problem that micro-bending is generated and transmission loss is increased.

[0006] When an excessive tension is applied when forming the protective layer, the plastic optical fiber elongates in the longitudinal direction, so that a plastic optical fiber having a desired outer diameter may be obtained. There was a problem that it was not possible.

[0007] The present invention has been made based on such a point, the object is to have a desired outer diameter,
Another object of the present invention is to provide a plastic optical fiber with low transmission loss at low cost.

[0008]

In order to achieve the above-mentioned object, a plastic optical fiber according to the present invention comprises a surface of a plastic optical fiber in which a glass transition point of a part or all of the light transmitting portion is 90 ° C. or less. A plastic optical fiber that is made by integrating a transparent plastic into
The transparent plastic has at least the property of not deforming even after being integrated with the plastic optical fiber even at a temperature exceeding the thermal deformation temperature of the outermost layer of the plastic optical fiber, while before being integrated with the plastic optical fiber. Is characterized in that it has the property of being moldable below the heat distortion temperature of the outermost layer of the plastic optical fiber. At this time, it is considered that the transparent plastic has a property of being cured by a polymerization reaction. or,
It is considered that the transparent plastic has a property of being cured by a crosslinking reaction.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Here, one embodiment of the structure and the manufacturing method of a plastic optical fiber according to the present invention will be described.

In the present invention, first, a plastic optical fiber having a diameter smaller than a desired outer diameter and having a glass transition point of 90 ° C. or less of a material of a part or all of the light transmitting portion is known. It is manufactured by the method described above. At this time, the outer diameter of the plastic optical fiber may be smaller than the desired outer diameter of the plastic optical fiber.
mm plastic optical fiber
The outer diameter may be smaller than 0 mm. As an example of the constituent material, for example, a resin mainly composed of polymethyl methacrylate (PMMA) as disclosed in Japanese Patent Application Laid-Open No. H5-241036, International Publication No. WO93 / 08488, etc. There may be mentioned, for example, a compound having a refractive index distribution obtained by doping a compound having a high refractive index.

Next, a transparent plastic having heat resistance is coated on the surface of the plastic optical fiber by a known method,
For example, they are formed and integrated by a method of application or a method of extrusion coating using a known extruder.
As a transparent plastic constituent material, it has heat resistance that does not deform even at a temperature exceeding the thermal deformation temperature of the outermost layer of the plastic optical fiber, and liquefies at a temperature lower than the thermal deformation temperature of the outermost layer of the plastic optical fiber. A resin having the following properties is used. Examples of the resin having such properties include a resin that is cured by a polymerization reaction such as a silicone resin, a urethane resin, and an acrylic resin, and a resin that is cured by a crosslinking reaction.

The form of the resin which is cured by the polymerization reaction includes, for example, a mixture of a monomer and an initiator, a mixture of a monomer and an initiator with a solvent, and a method in which a polymer is dissolved in a monomer of the same type or different from the polymer to form an initiator. Additive mixtures and the like are known. Examples of the form of the resin that is cured by the crosslinking reaction include, for example, a mixture obtained by dissolving a polymer in a monomer of the same or different kind from the polymer and adding an initiator, and adding a crosslinking agent to a mixture obtained by dissolving a polymer in a soluble solvent. And those obtained by adding a crosslinking agent directly to a polymer are known.

Here, in consideration of the adhesion between the transparent plastic and the plastic optical fiber, a particularly preferable form of the transparent plastic material is one that dissolves or swells the outermost layer of the plastic optical fiber to some extent. desirable. For example, when a plastic optical fiber whose outermost layer is made of PMMA is used, a material using methanol as a solvent is preferably used.

[0014] Among the above-mentioned polymerization-cured resins or cross-linked cured resins, there are thermosetting resins and photo-curing resins. There are some which are cross-linked and hardened, but in the present invention, it is preferable to use a photo-curable resin which does not apply heat to the plastic optical fiber as much as possible when integrating a transparent plastic. Examples of the photo-curable resin include an ultraviolet-curable resin such as a urethane acrylic-based ultraviolet curable resin and a silicone acrylic-based ultraviolet curable resin.

As a method of forming a transparent plastic,
As described above, a method by coating, a method by extrusion coating using a known extruder, and the like can be adopted, and are not particularly limited. When forming by coating, for example, a coating apparatus as shown in FIG. 1 can be suitably used. In FIG. 1, reference numeral 1 denotes an optical fiber supply device, reference numeral 2 denotes a plastic optical fiber, reference numeral 3 denotes a coating die, reference numeral 4 denotes a coating material supply device, reference numeral 5 denotes an ultraviolet irradiation device, reference numeral 6 denotes a constant speed take-off device, and reference numeral. Reference numeral 7 denotes a winding device.

In FIG. 1, first, a plastic optical fiber 2 is introduced into a coating die 3 from an optical fiber supply device 1 at a predetermined speed, and a coating material supplied from a coating material supply device 4 is applied to the surface thereof. Is done. The plastic optical fiber 2 to which the coating material has been applied is continuously introduced into the ultraviolet irradiation device 5 and is irradiated with a predetermined amount of ultraviolet light to cure the coating material on the surface. The plastic optical fiber 2 having the coating material integrated on the surface in this way is wound up by the winding device 7 via the constant speed take-up device 6. When such an apparatus is used, the cured state of the coating material is controlled by adjusting the winding speed.

[0017]

EXAMPLES Examples of the present invention will be described below together with comparative examples. In the following examples, the final finished outer diameter is 1.0
1 shows an example of a case where a plastic optical fiber is manufactured so as to have a length of mm. In addition, as a constituent material of the plastic optical fiber, a resin mainly composed of PMMA is used.
A material doped with a compound having a high refractive index for controlling the refractive index was used.

Example 1 First, a plastic optical fiber having a GI type refractive index distribution of 0.9 mm in diameter was produced by heating and drawing a plastic optical fiber preform obtained by a known method. Next, this plastic optical fiber is set in a coating apparatus as shown in FIG. 1, and as a coating material, a urethane acrylate ultraviolet curable resin [manufactured by Nippon Synthetic Chemical Co., Ltd., UV-1700E: manufactured by Shin-Etsu Chemical Co., Ltd.] , DX-2400 = 100: 2.5
(Weight ratio)] in the coating die 3 filled with
After introduction at a linear speed of m / min,
00W, wavelength 250-400 nm (strongest spectrum 36
The coating material was cured by irradiating ultraviolet rays (5 nm) to produce a plastic optical fiber having an outer diameter of 1.0 mm and integrated with a transparent plastic.

Here, the heat shrinkage of the plastic optical fiber thus obtained after heating at 80 ° C. for 24 hours was 0.6%. Thereafter, a protective layer made of polyethylene was formed on the surface of the plastic optical fiber by extrusion coating, but no phenomenon was observed in which the outer diameter was reduced by elongation. The change in transmission loss at this time was 0.01 dB / m.

Example 2 First, a plastic optical fiber preform obtained by a known method was drawn by heating to produce a plastic optical fiber having an outer diameter of 0.9 mm and having a GI type refractive index distribution. Next, this plastic optical fiber is set in a coating apparatus as shown in FIG. 1, and as a coating material, a silicone acrylate ultraviolet curable resin containing a methanol solvent [Shin-Etsu Chemical Co., Ltd.
X-12-2400: Shin-Etsu Chemical Co., Ltd., DX
-2400 = 100: 2.5 (weight ratio)] into the coating die 3 at a linear velocity of 10 m / min.
The coating material was cured by irradiating ultraviolet rays of 00 nm (strongest spectrum: 365 nm) to produce a plastic optical fiber having an outer diameter of 1.0 mm and integrated with a transparent plastic.

Here, the heat shrinkage of the plastic optical fiber thus obtained after heating at 80 ° C. for 24 hours was 0.8%. Thereafter, a protective layer made of polyethylene was formed on the surface of the plastic optical fiber by extrusion coating, but no phenomenon was observed in which the outer diameter was reduced by elongation. The change in transmission loss at this time was 0.01 dB / m.

Example 3 First, a plastic optical fiber preform obtained by a known method was drawn by heating to produce a plastic optical fiber having an outer diameter of 0.9 mm and having a GI type refractive index distribution. Next, this plastic optical fiber is set in a coating apparatus as shown in FIG.
As a coating material, a mixed UV-curable resin of urethane acrylate and silicone acrylate [UV-1700E, manufactured by Nippon Synthetic Chemical Co., Ltd .: Shin-Etsu Chemical Co., Ltd.]
X-12-2400: Shin-Etsu Chemical Co., Ltd., DX
-2400 = 50: 50: 2.5 (weight ratio)] into the coating die 3 at a linear velocity of 10 m / min, and then, with the ultraviolet irradiation device 5, 400 W and a wavelength of 250 to
The coating material was cured by irradiating ultraviolet rays having a wavelength of 400 nm (strongest spectrum: 365 nm) to produce a plastic optical fiber having an outer diameter of 1.0 mm and integrated with a transparent plastic.

Here, the heat shrinkage of the plastic optical fiber thus obtained after heating at 80 ° C. for 24 hours was 0.7%. Thereafter, a protective layer made of polyethylene was formed on the surface of the plastic optical fiber by extrusion coating, but no phenomenon was observed in which the outer diameter was reduced by elongation. The change in transmission loss at this time was 0.01 dB / m.

COMPARATIVE EXAMPLE A plastic optical fiber preform obtained by a known method was heated and drawn to an outer diameter of 1.0 m.
A plastic optical fiber having a m-GI type refractive index distribution was manufactured.

The heat shrinkage of the thus obtained plastic optical fiber after heating at 80 ° C. for 24 hours was measured to be 3.6%. After that, when a protective layer made of polyethylene was formed on the surface of the plastic optical fiber by extrusion coating, the outer diameter was reduced from 1.0 mm to 0.9 mm by elongation. The change in transmission loss at this time was 0.4 dB / m.

[0026]

As described above in detail, according to the present invention, the transparent plastic integrated on the surface has heat resistance which does not deform even at a temperature exceeding the thermal deformation temperature of the outermost layer of the plastic optical fiber. Therefore, the plastic optical fiber does not shrink or elongate in the length direction even when heat or tension is applied during the formation of the protective layer. Therefore, it is possible to effectively suppress the occurrence of microbending caused by the thermal shrinkage of the plastic optical fiber, which has conventionally been a problem, and to reduce transmission loss. Further, as described above, the plastic optical fiber having a desired outer diameter can be stably manufactured because the resin does not expand in the length direction even when heat or tension is applied.

When a plastic optical fiber is manufactured by drawing a plastic optical fiber preform by heating, the outer diameter of the plastic optical fiber preform is made smaller than a desired outer diameter at the time of heating drawing. The length of the obtained plastic optical fiber becomes longer. Therefore, the manufacturing cost can be reduced, and an inexpensive plastic optical fiber can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a manufacturing apparatus for manufacturing a plastic optical fiber of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical fiber supply apparatus 2 ... Plastic optical fiber 3 ... Coating die 4 ... Coating material supply apparatus 5 ... Ultraviolet irradiation apparatus 6 ... Constant-speed take-up apparatus 7 ... Winding apparatus

Claims (3)

[Claims] 1. A plastic optical fiber in which a transparent plastic is integrated on the surface of a plastic optical fiber having a glass transition point of 90.degree. Plastics have at least the property that they do not deform even after exceeding the thermal deformation temperature of the outermost layer of the plastic optical fiber after being integrated with the plastic optical fiber. A plastic optical fiber having the property of being moldable below the heat distortion temperature of the outermost layer of the fiber. 2. The plastic optical fiber according to claim 1, wherein said transparent plastic has a property of being cured by a polymerization reaction. 3. The plastic optical fiber according to claim 1, wherein said transparent plastic has a property of being cured by a crosslinking reaction.