JPH04264504A - Plastic optical fiber made of heat resistant fluorine - Google Patents

Abstract

PURPOSE:To provide heat resistance and to allow long-distance transmission by forming the polytriazine of specific perfluoropolyether as a polymer for forming a fiber core. CONSTITUTION:The polytriazine of the perfluoropolyether expressed by formula I is used as the polymer for forming the fiber core. A copolymer of preferably perfluoro(2,2-dimethyl1,3-dioxol) and other copolymerizable ethylenic unsatd. monomer is used as the polymer for forming a sheath. The ethylenic unsatd. monomer copolymerizable with the perfluoro(2,2-dmethyl1,3-dioxol) is exemplified by ethylene, etc. The polytriazine of the perfluoropolyether expressed by the formula I is amorphous, is highly transparent and has the heat resistance as high as >=150 deg.C glass transition temp. This optical fiber contains C-H bond at a lower ratio and has extremely low water absorptivity and is, therefore, excellent in optical transmission characteristics and can make long-distance transmission of >=1km.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a plastic optical fiber, and more specifically, it has heat resistance that can be used for optical fiber cords, optical fiber cables, etc., and has a length of 1 km.
This invention relates to plastic optical fibers capable of long-distance transmission.

0002

[Prior Art] Conventionally, as an optical fiber, inorganic glass optical fibers that can perform excellent optical transmission over a wide wavelength range are known, but these optical fibers have poor workability and are susceptible to bending stress. However, plastic-based optical fibers have been developed and put into practical use as optical fibers that are easier to process.

This plastic optical fiber is made of polymethyl methacrylate (hereinafter referred to as PMMA) and polycarbonate (hereinafter referred to as PMMA), which have a large refractive index and good light transmittance.
The basic structural units are a core material (core) made of a polymer such as C) and a sheath material (cladding) made of a transparent polymer such as a fluorine-containing polymer having a lower refractive index than the core material.

[0004] These core-clad type optical fibers (optical fiber strands) include bulk optical fibers in which a functional protective layer is provided on the optical fiber strands, and optical fiber strands coated with a jacket material. Known are coated optical fiber cords, aggregated optical fibers that are aggregates of bulk optical fibers, and optical fiber cables in which bulk optical fibers are provided with tension members and the like.

[0005]

[Problems to be Solved by the Invention] However, these all-plastic optical fibers have a large number of C-H bonds in the molecules of the polymer constituting the core, and the expansion and contraction of the C-H bonds,
Light absorption due to vibration exists in the low wavelength region, and its 5th to 8th overtones also exist in the near-infrared and visible regions, that is, in the wavelength region of 400 nm or more, and are the cause of large optical transmission losses in this wavelength region. There is.

For example, the transmission loss due to light absorption based on the C-H bond of an optical fiber having a core of polymethyl methacrylate is approximately 100 dB/Km at a wavelength of 650 nm, 7
At a wavelength of 80 nm, it is approximately 400 dB/Km. Furthermore, the optical transmission loss of an optical fiber whose core is d8-PMMA, in which H atoms in polymethyl methacrylate are replaced with deuterium, is said to be 50 dB/Km at a wavelength of 780 nm. Since PMMA has a high water absorption rate, the core absorbs water over time, resulting in an increase in optical transmission loss over time.

[0007] A low-cost LED that emits light in the near-infrared region and is capable of high-output, high-speed data transmission is available.
All-plastic optical fibers that have been developed in the past are produced in large quantities, but these LEs capable of emitting near-infrared light
Because D cannot be used, it is difficult to perform optical transmission over 100 meters with a single optical fiber, and the development of LAN using plastic optical fibers is also delayed.

[0008] Therefore, in recent years, the development of plastic optical fibers capable of transmitting light in the near-infrared region has been studied. The publication discloses an invention of an optical fiber having a core made of a fluoroalkyl ester polymer of α-fluoroacrylic acid and a sheath made of a vinylidene fluoride-tetrafluoroethylene copolymer.

However, the heat resistance of this α-fluoroacrylic acid ester is 100 to 120 at the glass transition temperature.
℃, the operating temperature range of the optical fiber is 100℃.
There were limitations as follows.

0010

[Means for Solving the Problems] The present inventors have completed the present invention as a result of studies to find a method for solving the above problems.The gist of the invention is as follows. The heat-resistant fluorine-based plastic optical fiber uses polytriazine, a perfluoropolyether represented by the general formula (1), as a core forming polymer.

[Case 2]

The perfluoropolyether polytriazine used in the present invention can be synthesized by the following method.

First, hexafluoropropylene oxide is polymerized using a difunctional polymerization initiator to obtain an oligomer. Both ends of this oligomer are nitrified by a conventional method to obtain dinitrile [A]. Diamidine [B] is obtained by treating this dinitrile [A] with ammonia.

[0013] This dinitrile [A] and diamidine [B]
is polyadded to obtain polyimidoyl azine [C]. By reacting this polyimidoyl azine [C] with the terminal acid fluoride of hexafluoropropylene oxide, a high molecular weight perfluoropolyether polytriazine is obtained.

The above reaction will be briefly summarized in a scheme.

[Chemical formula 3]

[C4]

[C5]

[C6]

The perfluoropolyether polytriazine thus obtained is amorphous, has excellent transparency, and has a refractive index of 1.
．． 33 to 1.36, and has a glass transition temperature of 15
It has high heat resistance of 0° C. or higher, and desirably has a number average molecular weight of 15,000 or higher in order to obtain an optical fiber with toughness.

The sheath-forming polymer that can be preferably used in carrying out the present invention is perfluoro(2,2-dimethyl-
1,3-dioxole) and other copolymerizable ethylenically unsaturated monomers. Perfluoro(2,2-dimethyl-1,3) used in carrying out the present invention
-dioxole) can be synthesized, for example, by the method described in US Pat. No. 3,865,845. Further, the copolymer is disclosed in US Patent No. 397803, for example.
It can be manufactured by the method described in Publication No. 0.

Ethylenically unsaturated monomers copolymerizable with perfluoro(2,2-dimethyloxole) include:
For example, ethylene, propylene, isobutylene, butene-
1. Methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, CF2
=CF2, CHF=CF2, CH2=CF2, CH
2=CHF, CCl=CF2, CHCl=CF2,
CCl2=CF2, CClF=CCIF, CHF=CC
12, CH2=CClF, CCL2=CClF, etc., fluoropropylene compounds, such as CF3CF=CF2
, CF3CF=CHF, and monomers having further functional groups, such as perfluoro(alkyl vinyl ether),
Methyl-3-{1-[difluoro[(trifluoroethenyl)oxy]methyl]-1,2,2,2-tetrafluoroethoxy}-2,2,3,3-tetrafluoropropanoate, 2-{ Specific examples include 1-[difluoro[(trifluoroethenyl)oxy]methyl]-1,2,2,2-tetrafluoroethoxy}-1,1,2,2-tetrafluoroethanesulfonyl fluorite, etc. Can be done.

[0018] The sheath-forming polymer has a refractive index of 1.29 to
1.35, the polymer needs to be amorphous and highly transparent. In order to obtain a sheath-forming polymer with such properties, perfluoro(2,2-dimethyl-1,
3-dioxole) polymerization ratio is 20 to 100 mol%,
It is preferably in the range of 25 to 99.7 mol%. In order to improve the thermal fluidity of the sheath-forming polymer while maintaining its toughness, a perfluoro(2,2-dimethyl-1,3-dioxole) polymer having a number average molecular weight of 15,000 or more is used. On the other hand, the number average molecular weight 10,0 which has a plasticizing effect
00 or less plasticizer, especially perfluoroalkyl ether, in an amount of 1 to 50% by weight, preferably 5% by weight, based on the above polymer.
It is preferable to add it in a proportion of ~30% by weight. This plasticizer causes extremely little leaching phenomenon and is preferred in the practice of the present invention. Specific examples of perfluoroalkyl ether include F-(CF2CF2-O)
n-CF2CF3, F-[CF(CF3)CF2-O]
n-CF2CF3, F-(CF2CF2CF2-O)n
-CF2CF3,F-[CF(CF3)CF2CF2-
O]n-CF3CF3 and the like, and commercially available products include Demnum (trademark) manufactured by Daikin Industries, Ltd. and Krytox (trademark) manufactured by DuPont.

The optical fiber of the present invention can be produced by a core-sheath type composite spinning method, a ram extrusion method, a sheath material melt coating method, a solvent coating method, etc., but these optical fibers can be formed in as few steps as possible. Care must be taken to perform this in dust-free conditions. It is particularly preferable to make an optical fiber by a core-sheath type composite spinning method, and in this case, the melt flow ratios [MFR1] and [MFR2] of the core-forming polymer and the sheath-forming polymer are [M
It is preferable to satisfy the relationship: FR1]≦[MFR2]. If an optical fiber is made by a composite spinning method using a combination of a core polymer and a sheath polymer that do not satisfy this relationship, the core-sheath structure will be disturbed and it will not be possible to obtain good optical transmission characteristics. Polymer MFR is JIS K-7210-
It was measured by a method based on Method A of No. 76. The value expressed as the number of grams of polymer discharged from the tip of the die nozzle in 10 minutes when 5 grams of polymer is filled into a die with a die length of 8 mm and an inner diameter of 2.0 mm and a load of 5 kg is applied at 230 ° C. be.

The all-plastic optical fiber of the present invention has a low C-H bond content and extremely low water absorption, so it has excellent light transmission characteristics and can transmit light from the visible region to the near-infrared region. It can be used as a liquid. Furthermore, since the transmission distance is 1 km or more and it has excellent heat resistance, it can be used in optical communication fields such as LAN and FA.

[0021]

[Examples] The present invention will be explained in more detail with reference to Examples below.

[0022]

[Reference example] Hexafluoropropylene oxide 100
LiOCF2CF2O as a polymerization initiator based on the weight part
0.5 parts by weight of Li was added and polymerized, followed by nitrification according to a conventional method. The obtained oligomer had a dinitrile purity of 90% and a number average molecular weight of 4,800. This dinitrile was purified by thin film distillation and brought into contact with ammonia to synthesize diamidine.

80 parts by weight of this dinitrile and 1 part by weight of diamidine
00 parts by weight to form polyimidoylamidine,
Furthermore, a polytriazine of perfluoropolyether having a molecular weight of about 1 million was synthesized by addition reaction with hexafluoropropylene oxide containing a terminal acid aluoride group. The obtained polymer had a refractive index of 1.35 and a glass transition point of 18.
At 0°C, the melt flow index (MI) is 1.3 (2
30°C, 5 kg).

[0024]

[Example 1] The above-synthesized polymer was used as a core-forming polymer, and the sheath-forming polymer was perfluoro(2,2-dimethyl-1,3-dioxole) (PDD)/tetrafluoroethylene (TFE) = 70/ 30 mol% copolymer (ηD = 1.30, Tg = 180 °C, MI = 14)
The fibers were spun using a composite spinning nozzle to obtain an optical fiber with an outer diameter of 1 mm.

[0025] The optical transmission loss of this optical fiber is 650 nm.
52dB/Km at a wavelength of 770nm, 73dB at a wavelength of 770nm
/Km, and 80 dB/Km at a wavelength of 950 nm. Further, even when this optical fiber was left at 150° C. for 100 hours, no change in optical transmission loss was observed, indicating that it had excellent heat resistance.

[0026]

[Example 2] Using the core forming polymer used in Example 1,
PDD/TFE = 80/20 mol% as sheath forming polymer
90 parts by weight of a copolymer of F-[CF(CF3)-CF2
-O]n-CF2CF3 (Perfluoropolyether with a number average molecular weight of 8250: DuPont trademark Kryto
x 143AD) 10 parts by weight, refractive index 1.31,
An optical fiber having an outer diameter of 1 mm was obtained by the melt composite spinning method in the same manner as in Example 1 using a mixture having Tg = 171°C and MI = 15.3. The optical transmission loss of this optical fiber is 650
41dB/Km at nm, 67dB/K at 770nm
m, 89 dB/Km at 950 nm. Also, 1
No change in optical transmission loss was observed after being left at 50° C. for 100 hours.

[0027]

[Example 3] 90 parts by weight of the core-forming polymer used in Example 1 and F-(CF2-CF2-CF2-O)n-CF2C
F3 (perfluoropolyether with number average molecular weight 8000: Demnum S-200 manufactured by Daikin Industries, Ltd.) 10 parts by weight, refractive index 1.36, Tg = 165 ° C., MI =
The mixture of Example 8.3 was filled into a closed container with an inner diameter of 20 mm and an effective length of 1000 mm to produce a rod-shaped core-forming polymer molded article.

Melting the sheath-forming polymer used in Example 1,
It was shaped to form a pipe with an inner diameter of 20 mm and an outer diameter of 22 mm. A rod-shaped core-forming polymer was inserted into this pipe to form an optical fiber-forming rod. All of these operations were performed in a clean room with a cleanliness level of 100.

The rod for forming the optical fiber produced as described above is attached to a ram extruder, and the rod is extruded from a spinning nozzle by heating the 10 mm area of the lower end of the rod to 260° C. and applying a pressure of 3 kg/cm 2 . An optical fiber with a diameter of 1000 μm was obtained. The optical transmission loss of this optical fiber is 650n
59dB/Km for light at m, 96dB/Km for light at 770nm
Km, 950 nm light was 103 dB/Km. Further, no change in optical transmission loss was observed after this optical fiber was left at 150° C. for 100 hours.

Claims (1)

[Claims] 1. A heat-resistant fluorine-based plastic optical fiber comprising polytriazine, a perfluoropolyether represented by the general formula (1), as a core forming polymer. [Chemical formula 1]