JPH08160264A - Optical fiber - Google Patents

Abstract

PURPOSE: To suppress the generation of light scattering, light absorption and the deterioration of transmission loss by suppressing the advance of coloring or gelation due to the influence of oxygen molecule in a core layer and a clad layer at the time of being exposed at a high temp. in the atmosphere. CONSTITUTION: This optical fiber is provided with a core layer 1 consisting of a transparent resin, a clad layer 2 covering the outer periphery of the core layer 1 and consisting of a transparent resin having a smaller refractive index than that of the core layer 1 and a gas barrier layer 3 covering the outer periphery of the clad layer 2 and consisting of a resin high in gas barrier property which is impermeable to oxygen or hardly permeable to oxygen.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber, and more specifically, it is applied to a plastic optical fiber used in a vehicle interior, an engine room, a light guide, a device or a device, a medical device, an optical sensor or the like. In particular, when exposed to the atmosphere at a high temperature, it is possible to suppress the progress of coloring and gelation due to the effect of oxygen molecules, suppress the occurrence of light scattering and light absorption, and suppress the deterioration of transmission loss. Optical fiber that can be.

In recent years, in the field of automobiles, there is an increasing demand for weight reduction of the vehicle body in view of low fuel consumption and waste gas regulation. On the other hand, various sensors have come to be used along with the sophistication and safety of automobiles, and the number of wires of electric cables has become enormous. For this reason, there is a problem that the enlargement of the electric wires and cables hinders the weight reduction of the automobile.

As a means for solving the problem of hindering the weight reduction of automobiles due to the enlargement of electric cables,
Techniques for reducing the number of wires by multiplex communication have been studied. For example, what has been connected with 50 electric wires until now is to use one electric cable. However, if what is connected with these 50 electric cables is performed with one electric wire cable, electromagnetic noise is generated especially in the engine room. Therefore, due to the influence of this electromagnetic noise, noise is generated in the signal. There is a problem that they are superposed and malfunction occurs. Against this background, there is a demand for optical fiber communication that can realize multiplexing and high-speed communication without being affected by electromagnetic noise.

In order to carry out optical fiber communication in an automobile, it must be easy to handle and resistant to mechanical shock and vibration, and must be used in combination with a guarantee of bending characteristics by high-density wiring and an optical connector. Therefore, cost reduction as a total component is required. Due to such requirements, large-diameter plastic optical fibers are expected to be expected as short-distance optical communication cables in automobiles.

[0005]

2. Description of the Related Art Conventional optical fibers generally have a core material made of acrylic resin, and therefore have a heat resistance of 100.degree.
Below and low temperature. Therefore, with this conventional optical fiber, 125 ° C. required in the engine room of an automobile or 150 ° C. required in the engine room of a diesel vehicle.
Since the temperature cannot be satisfied with high temperature, high heat-resistant plastic optical fiber is desired.

Conventionally, as a high heat resistant plastic optical fiber, an optical fiber using a polycarbonate resin having a higher heat resistance than an acrylic resin or a thermosetting silicone resin as a core material has been proposed.

[0007]

However, in the conventional optical fiber using the core material made of the above polycarbonate resin, since the benzene nucleus having a double bond is included, the influence of the electronic transition absorption is In particular,
It appears in the short wavelength region from blue to green, and when it emits white light, it becomes yellowish, which is an unnatural color for use as a light guide, which is a problem.

On the other hand, in the conventional optical fiber using the core material made of the latter thermosetting silicone resin, the thermosetting silicone resin is used as the core material.
It takes a long time to cure the core. Therefore, there is a problem that it is difficult to mass-produce optical fibers at high speed. In order to solve the above-mentioned problem that has occurred in the conventional optical fiber using a core material made of a polycarbonate resin or a thermosetting silicone resin, conventionally, as shown in FIG. An optical fiber coated with a clad layer 102 made of a norbornene-based resin (for example, trade name “ARTON”, manufactured by Japan Synthetic Rubber Co., Ltd.) has been studied. The same applies when norbornene-based resin is used for the core layer 101 itself.

This clad layer 102 or core layer 10
Since the conventional optical fiber using the norbornene-based resin in 1 does not have a double bond in the chemical structure, it is possible to solve the problem of visible light transmission, which was a problem in the optical fiber using the polycarbonate resin described above. It is expected to be possible. Further, since it is composed of a thermoplastic resin, it is expected that mass production can be realized as compared with the optical fiber using the thermosetting silicone resin described above. In addition, since the glass transition temperature is as high as 171 ° C., it is better than the optical fiber using the acrylic resin described above.
It is expected that the heat resistance can be improved. As described above, the optical fiber using the norbornene-based resin is expected to exhibit the above-mentioned excellent characteristics.

However, in this conventional optical fiber, when the norbornene-based resin to be the cladding layer 102 or the core layer 101 is exposed to the atmosphere at a high temperature, coloring and gelation due to the effect of oxygen molecules proceed, so that light scattering and gelation occur. There is a problem that light absorption occurs and the transmission loss of the optical fiber deteriorates. Even if the core layer 101, instead of the clad layer 102, is made of norbornene-based resin, the problem of norbornene-based resin itself cannot be solved, so that the same problem as described above occurs.

Therefore, according to the present invention, when exposed to the atmosphere at a high temperature, the progress of coloring and gelation due to the influence of oxygen molecules can be suppressed, and the occurrence of light scattering and light absorption can be suppressed, thereby deteriorating the transmission loss. It is an object of the present invention to provide an optical fiber capable of suppressing the above.

[0012]

According to the first aspect of the present invention,
A core layer made of a transparent resin, a clad layer made of a transparent resin having a smaller refractive index than the core layer coated on the outer periphery of the core layer, and an oxygen coated on the outer periphery of the clad layer do not permeate, or oxygen And a gas barrier layer made of a resin having a high gas barrier property that does not easily pass through.

According to a second aspect of the present invention, in the above first aspect of the invention, the core layer is a norbornene-based resin,
It is characterized by comprising at least one of a polycarbonate resin, an acrylic resin, a norbornene resin derivative resin, a polycarbonate resin derivative resin, and an acrylic resin derivative resin. Claim 3
According to the invention described in claims 1 and 2,
The main component of the gas barrier layer is a polymer having ethylene and vinyl alcohol as a constituent unit or polyvinyl alcohol.

[0014]

In the present invention, a core layer made of a transparent resin, a clad layer made of a transparent resin having a smaller refractive index than the core layer coated on the outer periphery of the core layer, and at least a high temperature coated on the outer periphery of the clad layer are provided. A gas barrier layer made of a resin having high gas barrier properties that does not transmit oxygen or does not easily transmit oxygen is configured.

Therefore, when exposed to the atmosphere at a high temperature, the gas barrier layer can suppress the progress of coloring and gelation due to the influence of oxygen molecules, so that the occurrence of light scattering and light absorption can be suppressed to reduce the transmission loss. Deterioration can be suppressed. In the present invention, the core layer, in consideration of mass production and high heat resistance, norbornene-based resin, polycarbonate resin,
It is preferable to be composed of at least one of a norbornene-based resin derivative resin and a polycarbonate resin derivative resin.

Of these, the norbornene-based resin, which is a thermoplastic resin having a high glass transition temperature and having no double bond in its chemical structure, is more preferable. In this case, a polycarbonate resin is conventionally used. It is possible to solve the problem of visible light transmissivity, which is a problem with the above optical fiber, and to realize mass production as compared with the conventional optical fiber using a thermosetting silicone resin. Moreover, the heat resistance can be improved as compared with the optical fiber using the acrylic resin.

In the present invention, considering that it is difficult for oxygen to permeate at high temperature in the gas barrier layer, a copolymer of ethylene and vinyl acetate or a part or all of a saponified product thereof or a part of polyvinyl acetate is used. Alternatively, it is preferable to be composed of all saponified products.

[0018]

1 is a perspective view showing the structure of an optical fiber according to an embodiment of the present invention. In FIG. 1, 1 is a core layer made of a transparent resin, 2 is a clad layer made of a transparent resin having a smaller refractive index than the core layer 1 coated on the outer periphery of the core layer 1, and 3 is an outer periphery of the clad layer 2. The gas barrier layer is made of a resin having a high gas barrier property that does not allow or does not allow oxygen to pass through.

In the optical fiber of this embodiment, the core layer 1 and the clad layer 2 are individually melted by an extruder by the composite melt extrusion method, and the clad layer 2 is formed on the outer periphery of the core layer 1 by a double nozzle.
Was extruded, solidified by air cooling, and continuously made into a fiber by a winder. At this time, the outer diameter of the fiber is determined by the extrusion amount of the core layer 1 and the clad layer 2 and the speed of the winder. The fiber diameter is about 1 mm, and the thickness of the cladding layer 2 is about 20 μm.

On the outer periphery of the clad layer 2, there is provided a gas barrier layer 3 having a gas barrier property of hardly permeating oxygen at a high temperature at a temperature of 0.2 mm, which is made of a polymer having ethylene and vinyl alcohol as a constituent unit or a resin made of polyvinyl alcohol. It was coated to a moderate thickness. The light source used for evaluation of each optical characteristic described later is an LED (manufactured by Stanley Co., Ltd., trade name; FH511) having an emission wavelength of 660 nm, and the output light from the optical fiber is a power meter (manufactured by Ando Denki Co., Ltd. Name; AQ-1135). The heat resistance is 3m in length in a constant temperature bath set at 150 ° C.
The optical fiber of No. 2 was exposed and the amount of change in the output light from the optical fiber was measured.

Hereinafter, examples of the present invention will be described in comparison with comparative examples. First, a comparative example will be described. (Comparative Example) In a comparative example, as shown in FIG. 1, an optical fiber up to the outer periphery of the core layer 1 covered with the cladding layer 2 will be described. In the comparative example, the core material constituting the core layer 1 is
Norbornene resin (manufactured by Japan Synthetic Rubber Co., Ltd., product name; AR
TON, refractive index: 1.51), and the cladding material forming the cladding layer 2 is a polyvinylidene fluoride resin (Kureha Chemical Industry Co., Ltd., trade name; KF # 850, refractive index: 1.
42) was used to coat the outer periphery of the core layer 1 with the cladding layer 2 to form an optical fiber.

In the optical fiber of this comparative example, the relationship between the fiber length and the output of the optical fiber was examined and the transmission loss was calculated. As shown in FIG. 2, it was 1.40 dB / m.
Further, as a result of conducting a high temperature storage test at 150 ° C. of the optical fiber of this comparative example, as shown in FIG. 2, the time when the value per unit length of the change amount of the optical output exceeds 0.5 dB / m is 15 Since the time is short and the time is short, it was found that light scattering and light absorption occurred, and the transmission loss of the optical fiber was deteriorated. (Embodiment 1) This embodiment will be described using the optical fiber shown in FIG. A norbornene-based resin (manufactured by Japan Synthetic Rubber Co., Ltd., trade name; ARTO
N, refractive index: 1.51), and the clad material constituting the clad layer 2 is polyvinylidene fluoride (Kureha Chemical Industry Co., Ltd., trade name; KF # 850) and polymethylmethacrylate (Sumitomo Chemical Co., Ltd.). As described above, the clad layer 2 was coated on the outer periphery of the core layer 1 using a solid solution having a composition of the product, trade name: Sumipec LO). At this time, the former polyvinylidene fluoride and the latter polymethylmethacrylate had a weight fraction of 70/30 and a refractive index of 1.44.

Next, a resin (a product of Kuraray Co., Ltd., trade name; Eval EP-E10) made of a polymer having ethylene and vinyl alcohol as constitutional units is provided on the outer periphery of the clad layer 2.
The gas barrier layer 3 composed of 5) was coated with a thickness of about 0.2 mm. In the optical fiber of this example, when the transmission loss was calculated from the fiber length and the inclination of the optical fiber output,
As shown in FIG. 2, it was 1.46 dB / m, which is the same as the optical fiber using the norbornene-based resin for the core layer 1 and the polyvinylidene fluoride resin for the cladding layer 2 of the comparative example.

As a result of a high temperature storage test of this optical fiber at 150 ° C., the time when the value per unit length of the change amount of the optical output exceeds 0.5 dB / m is 300 as shown in FIG. Since it is longer than the time, it was found that the transmission loss of the optical fiber when exposed to the atmosphere at a high temperature can be significantly improved as compared with the optical fiber of the comparative example. (Embodiment 2) This embodiment will be described by using the optical fiber shown in FIG. The core material constituting the core layer 1 is a norbornene resin (manufactured by Japan Synthetic Rubber Co., Ltd.,
Product name; ARTON, refractive index: 1.51), and the clad material that constitutes the clad layer 2 is polyvinylidene fluoride (Kureha Chemical Industry Co., Ltd., product name: KF # 850) and polymethylmethacrylate (Sumitomo). As described above, the clad layer 2 was coated on the outer periphery of the core layer 1 using a solid solution having a composition of Chemical Industry Co., Ltd., trade name: Sumipec LO). At this time, the former polyvinylidene fluoride and the latter polymethylmethacrylate had a weight fraction of 70/30 and a refractive index of 1.44.

Next, on the outer periphery of the clad layer 2, a resin (a product of Kuraray Co., Ltd., trade name; Eval EP-E10) made of a polymer containing ethylene and vinyl alcohol as constitutional units.
The gas barrier layer 3 composed of 5) was coated with a thickness of about 0.2 mm. Further, an outer periphery of the gas barrier layer 3 was coated with a disturbance light prevention layer (manufactured by Monsanto Co., Ltd., trade name: Santoprene 251-92) for about 0.4 mm in order to prevent disturbance light, thereby forming an optical fiber.

In the optical fiber of this example, the transmission loss was calculated from the fiber length and the inclination of the optical fiber output. As shown in FIG. 2, the core layer 1 of the comparative example was norbornene-based resin, and the cladding layer 2 was polyfluorinated. It was 1.44 dB / m like the optical fiber using vinylidene resin. As a result of a high temperature storage test of this optical fiber at 150 ° C., as shown in FIG. 2, when the amount of change in the optical output exceeds a value of 0.5 dB / m per unit length, as shown in FIG.
Since it is 0 hours or more, it was found that the transmission loss of the optical fiber when exposed to the atmosphere at a high temperature can be significantly improved as compared with the optical fiber of the comparative example. (Embodiment 3) This embodiment will be described using the optical fiber shown in FIG. A norbornene-based resin (manufactured by Japan Synthetic Rubber Co., Ltd., trade name; ARTO
N, refractive index: 1.51), and the clad material constituting the clad layer 2 is polyvinylidene fluoride (Kureha Chemical Industry Co., Ltd., trade name; KF # 850) and polymethylmethacrylate (Sumitomo Chemical Co., Ltd.). As described above, the clad layer 2 was coated on the outer periphery of the core layer 1 using a solid solution having a composition of the product, trade name: Sumipec LO). At this time, the former polyvinylidene fluoride and the latter polymethylmethacrylate had a weight fraction of 70/30 and a refractive index of 1.44.

Next, a gas barrier layer 3 made of a resin made of polyvinyl alcohol (Kuraray Co., Ltd., trade name; Poval PVA-117) is formed on the outer periphery of the clad layer 2 by 0.2.
It was coated with a thickness of about mm. In the optical fiber of this example, the transmission loss was calculated from the fiber length and the inclination of the output of the optical fiber. As shown in FIG.
As in the optical fiber using the polyvinylidene fluoride resin for the norbornene-based resin clad layer 2, it was 1.45 dBm.

As a result of a high temperature storage test of this optical fiber at 150 ° C., as shown in FIG. 2, the change amount of the optical output is as long as the value per unit length exceeds 0.5 dB / m. Since the light was emitted for 300 hours or more, it was found that the transmission loss of the optical fiber when exposed to the atmosphere at high temperature can be significantly improved as compared with the optical fiber of the comparative example.

In each of the above embodiments, the gas barrier layer 3
In the case of a preferred embodiment in which the core layer and the clad layer can be made difficult to react with oxygen by making it difficult to permeate oxygen at a high temperature by being composed of a polymer having ethylene and vinyl alcohol as a constitutional unit or polyvinyl alcohol However, the present invention is not limited to this, and the point is to configure a gas barrier layer made of a material that does not permeate oxygen or does not permeate oxygen even at high temperatures.

In each of the above-mentioned embodiments, the case where the core layer 1 is made of norbornene-based resin has been described, but the present invention is not limited to this. For example, a polycarbonate resin, a derivative resin of norbornene-based resin, and a polycarbonate. It may be composed of a resin derivative resin or the like. Of these, the norbornene-based resin, which is a thermoplastic resin having a high glass transition temperature and having no double bond in the chemical structure, is preferably used as in each of the above examples. In this case, the polycarbonate resin is used. It is possible to solve the problem of optical transparency of visible light, which is a problem with the used optical fiber, and it is possible to realize mass production as compared with an optical fiber using a thermosetting silicone resin. Moreover, the heat resistance can be improved as compared with the optical fiber using the acrylic resin.

[0031]

According to the present invention, when exposed to the atmosphere at a high temperature, the progress of coloring and gelation due to the effect of oxygen molecules can be suppressed, and the occurrence of light scattering and light absorption can be suppressed, resulting in transmission loss. There is an effect that the deterioration of can be suppressed.

[Brief description of drawings]

FIG. 1 is a perspective view showing the structure of an optical fiber according to an embodiment of the present invention.

FIG. 2 is a diagram showing the transmission loss in Examples 1, 2, 3 and a comparative example and the result of the time when the transmission loss exceeds 0.5 dB / m in a 150 ° C. high temperature storage test.

FIG. 3 is a perspective view showing a structure of a conventional optical fiber.

[Explanation of symbols]

 1 core layer 2 clad layer 3 gas barrier layer

Front Page Continuation (72) Inventor Hironobu Shinohara 2-11-24 Tsukiji, Chuo-ku, Tokyo Within Japan Synthetic Rubber Co., Ltd. (72) Toshitaka Otsuki 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd. (72) Inventor Yasuo Hara 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd. (72) Inventor Masahiro Tomatsu 654 Kawawa-cho, Tsuzuki-ku, Yokohama-shi, Kanagawa Tomi Shitsukasei Co., Ltd. (72) Inventor Takuyuki Sukegawa 654 Kawawa-cho, Tsuzuki-ku, Yokohama-shi, Kanagawa Fujitsukasei Co., Ltd. (72) Masaya Hirano 654 Kawawa-cho, Tsuzuki-ku, Yokohama-shi, Yokohama Fujitsu Kasei Co., Ltd.

Claims (3)

[Claims] 1. A core layer (1) made of a transparent resin, and a clad layer (2) made of a transparent resin and having a refractive index smaller than that of the core layer (1) coated on the outer periphery of the core layer (1). , Does not permeate the oxygen coated on the outer periphery of the clad layer (2),
Alternatively, an optical fiber having a gas barrier layer (3) made of a resin having a high gas barrier property that hardly permeates oxygen. 2. The core layer (1) is at least one of a norbornene resin, a polycarbonate resin, an acrylic resin, a norbornene resin derivative resin, a polycarbonate resin derivative resin and an acrylic resin derivative resin. The optical fiber according to claim 1, wherein the optical fiber comprises: 3. The optical fiber according to claim 1, wherein the main component of the gas barrier layer (3) is a polymer having ethylene and vinyl alcohol as a constituent unit or polyvinyl alcohol.