JPS59200202A - Optical transmission fiber - Google Patents

Abstract

PURPOSE:To obtain an optical transmission fiber having heat resistance, and superior flexibility and optical transmission characteristic by using a methyl methacrylate copolymer having a specified compsn. as a core component and a transparent resin or a fluororesin having a specified refractive index as a sheath component. CONSTITUTION:A methacrylate copolymer to be used as a core component is made from 30-80wt% methacrylate obtained by esterifying methacrylic acid or methacryloyl chloride with an alicyclic monool (ROH, R is >=8C alicyclic hydrocarbon group). A material to be used as a sheath component has a refractive index smaller than that of the core component by at least 3%, and it is a transparent resin, such as vinylidene fluoride-tetrafluoroethylene copolymer or thermoplastic fluororubber, or a fluororubber. As a result, the obtained optical transmission fiber has heat resistance, and superior flexibility and optical transmission characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical transmission line (JFT) having a core-sheath structure and having excellent heat resistance and flexibility.

Optical transmission fibers have traditionally been manufactured using a strong glass material as a base material, and are widely used as optical signal transmission media for measurement control between and within devices, for data transmission, for medical purposes, for decoration, and for image transmission. There is. However, optical transmission lines IT based on glass-based materials have the disadvantage of poor flexibility unless they are made of fibers with a thin inner diameter, and are prone to breakage.
Recently, various attempts have been made to make this out of plastic, probably because it has a very high specific gravity and is expensive, including the connector.

The extraordinary feature of using plastic is that it is lightweight, and even fibers with a thick inner diameter are strong and flexible.Therefore, high apertures and large diameters are possible, and it is easy to combine with light receiving and emitting elements. It has excellent operability. The general method for manufacturing such optical transmission fibers using plastic snacks is to use a plastic with a lower refractive index and good light transmittance as a core component, and a plastic with a lower refractive index and good optical transparency as a core component. A fiber having a core-sheath structure is formed using transparent plastic as a sheath component. This method transmits light by reflecting it at the core-sheath interface, and the larger the difference in refractive index between the plastics that make up the core and the sheath, the better the light transmission properties.

Amorphous materials are preferable as plastics with high light transmittance, and from an industrial perspective, polymethyl methacrylate, polystyrene, and I/I materials that are attracting attention (for example, Japanese Patent Publication No. 43-8978, Japanese Patent Publication No. 8978, No. 53-21660 Public N
)0 However, as the temperature of such plastic optical transmission fibers increases, the light guiding loss increases, and there are cases in which they lack reliability as an optical signal medium.

Also, it has some drawbacks in heat resistance, so it can be used for moving objects such as automobiles, etc.
When applied to ships, aircraft, robots, etc., there are restrictions on the uses and locations. The upper limit temperature for polymethyl methacrylate and polystyrene is approximately 80'C.
At higher temperatures, the heat shrinks or becomes larger.
It has drawbacks such as deformation and fluctuations in its microstructure, making it unable to perform its function as an optical transmission fiber.
Furthermore, once it is used under a temperature condition of 80 degrees Celsius or higher, the light guide loss will be large even if it is returned to room temperature, making it impossible to use it again, which means that it can only be used within a narrow temperature range. It has been desired to develop a plastic optical transmission fiber with excellent heat resistance.

In view of the current situation, the present inventors investigated the development of plastic optical transmission fibers with excellent heat resistance and optical transmission properties, and first determined that the ester moiety was an alicyclic fiber having 8 or more carbon atoms. A polymer made of methacrylic acid ester having a hydrocarbon group is used as a core component, and the core component 1) also contains at least 3
We succeeded in obtaining a light transmitting fiber with excellent heat resistance characterized by using a transparent resin with a refractive index that is % lower as a sheath component, and have already applied for a patent (Patent Application No. 10506 of 1982).
No. 9).

The optical transmission fiber of the invention according to the application was satisfactory in terms of heat resistance, but was it flexible? Regarding the second issue, there was still room for consideration.

Therefore, the present inventors have conducted extensive research into developing a plastic optical transmission fiber that has excellent heat resistance, superior flexibility, and excellent optical transmission properties, and as a result, has arrived at the present invention. .

That is, the present invention provides methacrylic acid esters having an alicyclic hydrocarbon group having 8 or more carbon atoms in the ester moiety.
Weight average molecular weight containing 0% by weight 3 x 1. O'
Light transmission with excellent heat resistance and flexibility, with a core component of ~7X10'' methyl methacrylate copolymer and a transparent resin having a refractive index at least 3% smaller than the core component, or a fluorine comb as a sheath component. It provides fiber.

In the temperature range from room temperature to around 80'C, the optical transmission fiber of the present invention has a lower light guide loss that occurs as the temperature rises, compared to conventionally proposed optical transmission fibers that use polymethyl methacrylate as the core component. Even if the rate of increase is small, the reliability as an optical signal transmission medium can be significantly improved. Furthermore, unexpectedly, there is almost no increase in light guiding loss even at temperatures at which the conventionally proposed optical transmission fibers cannot be used, and in terms of flexibility, there is no practical problem. It is a material that does not provide optical transmission fiber.

In the present invention, the methacrylic acid ester whose ester moiety has an alicyclic hydrocarbon group having 8 or more carbon atoms is a methacrylic acid ester or an acid chloride thereof having the formula RO
It is obtained by esterifying H with an alicyclic hydrocarbon/monool.

Alicyclic hydrocarbons/monols represented by the formula ROH include 2,6-dimethylcyclohexanol, 1-adamantanol, 2-agmantal, and 3-methyl-1-
Agmanthal/3,5-dimethyl-1-7 gmantal, 3-ethyl atamantamel, 3-methyl-5
-ethyl-1-agmantal, 3,5.8-)diethyl-1-adamantanol and 3,5-tumethyl-
8-ethyl-1-adamantanol, octahythro 4
．． fumentanoinden-5-ol, octahydro-
4,7-Mensonoinden-1-ylmethanol, 3-
Hydroxy-2,6,6-)limethyl-bicyclo[3,
1,1]hebutanol, 3,7゜7-drimethyl-4-
Hydroxy-bicyclo[4°1.0]butamele, borneol, isoborneol, 2-methyl camphanol, 7-ethyl alcohol, termenthol, p-menthan-2-ol, p-menthan-8-ol, 2,
Examples include alicyclic hydrocarbons and monools such as 2,5-trimethylcyclohexal-7-al.

Among the methacrylic esters obtained from these, particularly preferred ones include fentyl methacrylate, de-menthyl methacrylate, bornyl methacrylate, inbornyl methacrylate, 1-adamantyl methacrylate,
Mention may be made of 3.5-dimethyl-1-agemantyl methacrylate.

The reason why the ester moiety is limited to an alicyclic hydrocarbon group having 8 or more carbon atoms is that in the case of an aromatic hydrocarbon group,
'This is because the light guide loss in optical transmission 1 and miscellaneous is extremely large, which limits its use as an optical signal transmission medium.

Among alicyclic hydrocarbon groups having 8 or more carbon atoms, alicyclic hydrocarbon groups having 10 or more carbon atoms are particularly preferably used, and in this case, they have a high contribution rate to improving heat resistance.

When a methacrylic acid ester having an alicyclic hydrocarbon group having 7 or less carbon atoms is used, heat resistance does not improve. Further, even when the number of carbon atoms is 8 or more, linear hydrocarbon groups such as methacrylic acid esters such as n-octyl methacrylate and n-dodecyl methacrylate do not contribute to improving heat resistance. On the other hand, the upper limit of the number of carbon atoms in the alicyclic hydrocarbon is desirably up to about 20, and if it exceeds that number, the mechanical strength of the polymer tends to decrease significantly.

In the present invention, the proportion of the methacrylic acid ester component having an alicyclic hydrocarbon group having 8 or more carbon atoms used in the core component is 30 to 80% (hereinafter simply referred to as %) of the entire polymer constituting the core component. ).

If it is less than 3″0%, it has excellent flexibility, but
It is difficult to obtain materials that have heat resistance of 130°C or higher; on the other hand,
If it exceeds 80%, heat resistance is excellent, but visibility is insufficient for practical use, which is not preferable.

In addition, in the present invention, the weight average molecular weight of the methyl methacrylate copolymer forming the core component is 3 x 104 to 7 x 10
If the weight average molecular weight does not reach 3 x 104, the flexibility will be insufficient, while if it exceeds 7 x 105, the processability will be poor, which is not preferred in practice.

Furthermore, the copolymer mainly composed of methyl methacrylate, which is the core component of the present invention, can contain an alkyl acrylate having an alkyl group having 1 to 4 carbon atoms or an alkyl methacrylate component by copolymerization. . In order to maintain heat resistance, these copolymer components should be contained in the minimum necessary amount, preferably at an amount not exceeding 5% based on the entire core component polymer.

The polymer mainly composed of methyl methacrylate of the present invention exhibits a higher refractive index than a single polymer of methyl methacrylate, and thus has favorable characteristics as a light transmission fiber.

On the other hand, as the sheath component, which is an important element of the pond constituting the present invention, a transparent resin or fluororubber having a refractive index that is at least 3% lower than that of the core component is used. If the difference in refractive index is smaller than 3%, the proportion of light reflected by the sheath component will be small and the light guide loss will be large. Specifically, the refractive index is preferably 1.42 or less, and it is preferably a non-crystalline, almost amorphous polymer that has good adhesion to the core component.

Preferred transparent cedar resins include fluororesins and thermoplastic fluororubbers. Examples of the fluororesin include vinyl fluoride, vinylidene fluoride, trifluoroethylenepetetrafluoroethylene, hexafluoropropene, trifluoromethyl trifluorovinyl ether, perfluoropropyl trifluorovinyl ether, perfluoroisopropyl methacrylate, Examples include fluorine-containing polymers such as perfluoro-tert 7-methyl methacrylate. Among these, particularly preferred fluororesins include vinylidene fluoride'-tetrafluoroethylene copolymer and Y-refluoroethylene-tetrafluoroethylene copolymer.
Vinylidene fluoride copolymer, vinylidene fluoride-tetrafluoroethylene-hexafluoropropene copolymer, perfluoroisopropyl methacrylate polymer, and perfluoro-Le+/L-butyl methacrylate polymer can be used.

In addition, thermoplastic fluororubber has a soft segment consisting of a fluororesin phase and a hard segment consisting of a fluororesin phase in its molecule, and at room temperature, the fluororesin phase undergoes physical crosslinking and has rubber elasticity. At higher temperatures, it behaves similarly to thermoplastic plastics.

As the fluororubber a forming the soft) segment, vinylidene fluoride/hexafluoropropylene or pentafluoropropylene/tetrafluoroethylene (molar ratio 45-9 (', 1:5-5 (1:0-35)
) polymers and perfluoro(alkyl vinyl ether)/tetrafluoroethylene/vinylidene fluoride' (molar ratio 15-75:0-85:0-85) polymers with molecular weights 30°000-1,20 (
'l, 000 to Fluorine Comb 10! The fluororesin phase forming the J5 part and hard segment is vinylidene fluoride/tetrafluoroethylene (molar ratio 0 to 100:
0 to 100) and polymers of ethylene/tetrafluoroethylene (molar ratio 40 to 60: 60 to 40) with a molecular weight of io, ooo to 400, OO
Thermoplastic fluororubber combined with 5 to 90 parts of O fluororesin can be mentioned. A typical thermoplastic fluororubber is Guyer Thermoplastic (manufactured by Daikin Industries, Ltd.).

A preferred fluororubber is vinylidene fluoride-hexafluoropropene copolymer.

Examples include vinylidene fluoride-pentafluoropropene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, and the like. Particularly preferred is vinylidene fluoride-hexafluoropropene copolymer.

In addition, by using a system in which a vulcanizing agent is slightly added to these fluororubbers, the fluororubber may be crosslinked by heat treatment or light irradiation after being coated on the core material, which will affect the heat resistance of the optical transmission fiber. Improve yourself. As a vulcanizing agent,
Examples include amines, polyols, and organic peroxides. The vulcanizing agent is preferably added in an amount of about 0.001 to about 1% by weight based on the fluororubber.

The core component polymer of the present invention can be produced by conventionally known methods such as suspension polymerization and bulk polymerization. In the Nakodashi suspension polymerization method, since a large amount of water is used, foreign substances contained therein are likely to get mixed into the polymer, and there is also a possibility that foreign substances can get mixed in during the dehydration process. If necessary, polymerization is performed after removing foreign substances such as dirt by filtration or distillation. A more desirable method is
First, the core component polymer is produced in step 2 of a continuous bulk polymerization step at high temperature followed by a continuous separation step of volatile components mainly containing residual unreacted monomers. There is a method in which the polymer manufacturing step and the optical transmission fiber manufacturing step are performed in a continuous process.

A production method in which the core component is bulk polymerized and then the core component and the sheath component are both formed from the obtained polymer by double extrusion is also a desirable method.

The radical polymerization initiators used in each of the above polymerizations include, for example, 2,2'-azobis(isobutyronitrile), 1,1'-azobis(cyclohexanecarbonitrile), 2,2'-azobis(2°4 -dimethylvaleronitrile), azobisisobutanol diacetate,
Azo compounds such as azo-tert-butane and -L
ert-butyl peroxide, dicumyl peroxide, methyl ethyl ketone peroxide, di-tert
Examples thereof include organic peroxides such as -butyl per7thaleate, di-tert-butyl peracetate, and di-tert-amyl peroxide Y. The addition ratio of these polymerization initiators is preferably 0.00 to 1% by mole based on the monomer.

Furthermore, in order to control the molecular weight, tert-butyl, lobutyl, n-octyl, 11-dodecyl mercaptan, and the like are added as chain transfer agents to the polymerization system in an amount of about 1 mol % or less based on the monomer.

On the other hand, the sheath component polymer can be produced by conventionally known methods. In the case of the sheath component polymer, in the case of the core component polymer, the manufacturing method has no effect on optical transmission properties, so make sure that foreign substances such as dust do not get mixed in, and if necessary, use filtration methods etc. Due to garbage etc.
After removing foreign matter, it is best to conduct a 2-2-2 test of the sheath component polymer and the 6-core component and the sheath component. Approximately 70:30 weight ratio
~98:2:), preferably about ]):20-95:
It is 5. The outer diameter of the optical transmission fiber having a core-sheath structure is about 0.15 to 1.5 mm, preferably about 0.20 to 1.0 mm.

As mentioned above, the present invention uses a specific polymer for the core component and the sheath component in an optical transmission fiber having a core-sheath structure, thereby greatly extending the applicable temperature range of conventional plastic optical transmission fibers. Expandable as well as heat resistant and practical flexibility,
Optical transmission! km, and its industrial equipment is extremely expensive. The optical transmission fiber of the present invention is
Since the normal temperature can be set to 110'C or higher, it can be applied to, for example, automobiles, ships, aircraft, or robots. In addition, the range of application can be expanded by relaxing temperature-limiting conditions for in-plant and in-building communications.

Next, the present invention will be explained in more detail with reference to examples, but the present invention should not be limited by these in any way.

In addition, a diffraction grating spectrometer with a /%logen tungsten lamp as a light source was used to measure the light guide loss in the examples.
The output intensities of the optical transmission fiber to be measured and the reference optical transmission fiber at a wavelength of 0 nm were read using a silicon 7 otodiode. The light intensity at the entrance and exit of optical transmission fibers with different fiber lengths L (km) is I, respectively. , ■, and the light guide loss α was determined using the following formula.

In this equation, the smaller the α value, the better the optical transmission performance.

The heat resistance test was conducted by heating the obtained optical transmission fiber for a predetermined period of time, and then measuring and comparing the light guide loss at the initial stage and after heating.

Flexibility was measured by winding the optical transmission fiber around several types of rods with different outer diameters, and determining the radius (r) at which it began to break. Therefore, the smaller the value of r, the greater the flexibility.

The weight average molecular weight was determined by gel permeation chromatography (GPC) using monodisperse polystyrene as a standard sample.
Measured by.

In addition, in each example, % means weight %.

Example 1 Bornyl methacrylate purified by vacuum distillation 35%
, 64% methyl methacrylate, 1% methyl acrylate, and 0.10% of ■-dodecylmercaptan azobis(2.4-dimethylvaleronitrile) based on these monomers.
% monomer mixture was prepared in the absence of oxygen and 1
Pre-polymerization was carried out in a reaction tank maintained at 50°C with a residence time of 8 hours. Then, the polymerization was completed in a 2-hour residence time with a screw conveyor maintained at 220'Ci, and the weight average molecular weight :40X104, refractive index 1.49
A methyl methacrylate copolymer was obtained. Furthermore, this copolymer was supplied to a vented extruder heated to 255°C,
A strand with a diameter of 110 m (discharged as a trowel core component) is discharged from the center of a double extrusion nozzle maintained at 235°C.

At the same time, vinylidene fluoride-tetrafluoroethylene copolymer (vinylidene fluoride 70%, refractive index 1.405,) volume flow index 140 was added from the outer nozzle.
(230°C)) was discharged as a sheath component and melted and coated on the core component to obtain a strand with a core-sheath structure.

The blending ratio of the core-sheath polymer was set at 90:10.

Next, in order to impart mechanical toughness, this strand was drawn 1.8 times to obtain a light transmission fiber with a diameter of about 0.0 mm and 751 fl.+1. When the light guide loss was measured at 25°C and 70°C, it was 340 dB/km and 370 dB/ion at a wavelength of 650 nm, respectively.

After heat-treating this optical transmission fiber at 125°C for 6 hours, the light guide loss was reduced again! As a result, 38t) dB/I
t+n, and showed excellent heat resistance. Also, when I measured the flexibility, I found that it could bend up to 70111f11.

Examples 2 to G Optical transmission fibers (0,85
~O, '75 +n+nφ). The light guide loss, heat resistance, and flexibility of the obtained optical transmission fiber were measured in the same manner as in Example 1, and the results are shown in Table 1.

As shown in Table 1, the optical transmission fibers had superior physical properties.

Example 7 Bornyl methacrylate purified by vacuum distillation 25%
, methyl methacrylate 72%, methyl acrylate 3%,
Furthermore, a monomer mixture in which 0.018% of n-dodecylmercaptan and 0.10% of 2,2'-azobis(2,4-dimethylvaleronitrile) were added to these monomers was filtered through a porous membrane. The mixture was prepared under a nitrogen stream without any suspended solids, and sent to a reaction tank maintained at 150'C for pre-polymerization for 8 hours. Then fed into a screw conveyor maintained at 200'C? W 2”J time 2
Polymerization is completed in hours, weight average molecular weight: 4.0X105
A methyl methacrylate copolymer having a refractive index of 1.49 was obtained.

Furthermore, this copolymer was heated to 255°C and then extruded at 23°C while removing unreacted monomers.
1 diameter from the center of a double extrusion nozzle maintained at 5°C
It is discharged as a core component in the form of strands. at the same time,
From the outer nozzle, as a sheath component, a vinylidene fluoride-hexafluorofurohene copolymer (hexafluoropropene: 30% content, Mooney viscosity ML+++o, 1
40"C:95) in ethyl acetate.
% solution and melt-coat the core component to form a core.
A strand of sheath structure was obtained. The thickness of the pod is approximately 10μm
Met. When the light guide loss was measured at 25°C and 70°C, it was found to be 300d at a wavelength of 650nm.
B/km, 320 dB/km.

After heat-treating this optical transmission fiber at 140°C for 10 hours,
As a result of re-measuring the light guide loss, it was 340 clB/1o, indicating excellent heat resistance. Furthermore, when the flexibility was measured, it was possible to bend up to 50 mm.

Comparative Example 1 Methacrylic acid ρ obtained by the same polymerization operation as Example 1
- The same vinylidene fluoride-tetrafluoroethylene copolymer as in Example 1, with the core component being a methyl methacrylate copolymer (weight average molecular weight 1 x 10 V) consisting of 40% menthyl, 57% methyl methacrylate, and 3% methyl acrylate. Using the coalescence as a sheath component, a core-sheath structure with a diameter of 0.85 mm is obtained by the same operation.
An optical transmission fiber was obtained. Flexibility was measured at 100m.
It was extremely fragile and could not be bent. 6
The light guide loss at 25°C at the SOnm wavelength was measured to be 400 dB/km. this thing 130
When heat treated at ℃ for 12 hours, it showed a light guide loss of 420 dB/'km, indicating excellent heat resistance.

Comparative Example 2 A methyl methacrylate copolymer having a weight average molecular weight of 8×10 5 and consisting of 70% bornyl methacrylate, 29% methyl methacrylate, and 1% methyl acrylate was obtained by the same polymerization operation as in Example 1.

This copolymer was fed to a vented extruder heated to 255°C to obtain a strand-like core, or the surface was not smooth. Also, set the temperature of the extruder to 290°
As a result of raising the temperature to C, the surface became smooth, but foaming was observed in the strands.

Comparative Example 3 A methyl methacrylate copolymer with a weight average molecular weight of 3 x 105 consisting of 10% bornyl methacrylate, 89% methyl methacrylate, and 1% methyl acrylate obtained by the same polymerization procedure as in Example 1 was used as the core component. Using the same fluororubber as in Example 7 as the sheath component, an optical transmission Mk fiber having a core-sheath structure and having a diameter of 0.85 m111 was obtained by the same operation. When the flexibility was measured, it could be bent up to 1.0 mm.

Also, 25°C and 70°C at a wavelength of 650n+n
When the light guide loss was measured at 350d for each
B/km and 500 dB/lv. When this optical transmission fiber was heat-treated at 150°C for 3 hours, 1000d
B/ showed a light guide loss of +n or more, and I]1 had good flexibility but poor heat resistance.

Comparative Example 4 Methacrylic acid 4-
An optical transmission fiber was obtained in the same manner as in Comparative Example 1 except that methylbenzyl was used. When this was treated at 100°C for 2 hours, it showed a light guide loss of 100 i') dB/km or more, and its heat resistance was poor.

Comparative Example 5 Methacrylic acid-1 as methacrylic acid ester of core component
An optical transmission fiber was obtained in the same manner as in Comparative Example 1 except that 1-octyl was used. When this was treated at 100'C for 2 hours, it showed a light guide loss of +n or more at 1000 clB/, and its heat resistance was poor.

Comparative Example 6 A methyl methacrylate copolymer with a weight average molecular weight of 4 x 104 consisting of 90% bornyl methacrylate, 9% methyl methacrylate, and 1% methyl acrylate obtained by the same polymerization operation as in Example 1 was used as a core component, Using the same vinylidene fluoride-tetrafluoroethylene copolymer as in Example 1 as the sheath component, a light transmission fiber having a core-sheath structure and having a diameter of 0.85 mm was obtained by the same operation. When the flexibility was measured, it was found that it could not be bent up to 100 nm and was extremely brittle. When the light guide loss was measured at 25°C at a wavelength of 650 nm, it was found that 400 d
It was B/km. When this material was heat-treated at 140°C for 24 hours, it showed a light guide loss of 410 clB/km,
It had excellent heat resistance.

Comparative Example 7 A light transmission fiber was obtained in the same manner as in Comparative Example 1, except that cyclohexyl methacrylate was used as the methacrylic ester of the core component. When this was treated at 100'C for 1 hour, it showed a light guide loss of more than 1'' per 1000 clB/, and its heat resistance was poor.

Patent applicant: Sumitomo Chemical Co., Ltd.

Claims (5)

[Claims] (1) A methyl methacrylate copolymer with a weight average molecular weight of 3x10' to 7x105 containing 30 to 80% by weight of a methacrylic ester having an alicyclic hydrocarbon group having 8 or more carbon atoms in the ester moiety as a core component. An optical transmission fiber characterized in that the sheath component is a transparent resin having a refractive index that is at least 3% lower than that of the core component, or a fluororubber. (2) A methacrylic acid ester having an alicyclic hydrocarbon group having 8 or more carbon atoms in the ester moiety is 7-enthyl methacrylate, methacrylic acid-! - The optical transmission fiber of item (1) above, which is menthyl, bornyl methacrylate, isobornyl methacrylate, adamantyl methacrylate or dimethyladamantyl methacrylate. (3) The transparent resin having a refractive index at least 3% lower than that of the core component is vinylidene fluoride-tetrafluoroethylene copolymer, trifluoroethylene-vinylidene fluoride copolymer, vinylidene fluoride-tetrafluoroethylene-hexafluoro The optical transmission fiber according to item (1) above, which is a propene copolymer, a perfluoroisopropyl methacrylate copolymer, a perfluoro-tert-butyl methacrylate polymer, or a thermoplastic fluororubber. (4) Item (1) above, wherein the fluororubber is a vinylidene fluoride-hexafluoropropene copolymer, a vinylidene fluoride-pentafluoropropene copolymer, or a vinylidene fluoride-chlorotrifluoroethylene copolymer. Optical transmission fiber. (5) The fluororubber forms a system containing a vulcanizing agent.
1) Optical transmission fiber.