KR20040083627A - Plastic Optical Fiber Consisting of Fluorine-substituted Polymer - Google Patents

Abstract

PURPOSE: A plastic optical fiber is provided, which is produced by using a fluorine-substituted polymer and has improved permeability and heat resistance and is not optically scattered in the range of near infrared rays. CONSTITUTION: The plastic optical fiber comprises the fluorine-substituted polymer represented by the formula, wherein RF is a C1-C5 linear or branched perfluoroalkyl radical, X1 and X2 are independently F or CF3, and n is a real number of 0.4-1. The plastic optical fiber is a step index type or a graded index type forming a refraction index distribution by a dopant.

Description

Plastic Optical Fiber Consisting of Fluorine-substituted Polymer

The present invention relates to a plastic optical fiber using a fluorine-substituted polymer, and more particularly, to a fluorine-substituted polymer as a new material of a plastic optical fiber, and in the case of a graded index optical fiber, a suitable dopant is selected for transmission. An object of the present invention is to provide an optical fiber with improved heat resistance.

Until now, the polymer materials used in plastic optical fibers have been mainly compounds having C-H bonds. Since the C-H bond-based polymer materials vibrate hydrogen atoms, stretching vibrations occur in the near-infrared (600-1550 nm) region, causing a large loss of absorption. For polymethylmethacrylates with C-H bonds, the theoretical absorption losses due to C-H bonds are estimated to be 105 dB / km for 650 nm light sources and 10,000 dB / km for 1300 nm light sources.

On the other hand, in the case of replacing hydrogen atoms with fluorine atoms in the carbon chain, absorption loss does not occur in the 650 nm light source. Absorption loss in 1300nm light source is theoretically about 1dB / km due to C-F coupling, so it can be seen that almost no absorption loss occurs.

Meanwhile, by removing functional groups such as carboxyl groups and carbonyl groups, heat resistance, hygroscopicity, chemical resistance, and flame retardancy can be improved. In addition, when the carboxyl group is present, absorption occurs in the near infrared region, and absorption occurs in the UV region due to the carbonyl group. Therefore, it is advantageous to remove such functional groups.

Representative materials of low light loss in the long wavelength region of 850nm or more are as follows. Japanese Patent Application Laid-Open No. 8-334634 introduces a plastic material for fully fluorine-substituted optics. The substance is a monomer such as perfluoro (2,2-dimethyl-1,3-dioxole) having an allylcyclic structure containing fluorine in the main chain. Is prepared by homopolymerization or radical copolymerization with monomers such as tetrafluoroethylene and hexafluoropropylene.They are polymerized from monomers having a fluorine-containing allylcyclic structure in the main chain and do not contain any CH bonds. It has an amorphous structure. Specifically, poly (heptafluoro-1-butene-trifluoro-vinylether) (poly (heptafluoro-1-butene-trifluoro-vinylether)) is brand name "CYTOP" by Asahi glass Co. of Japan. It is named and sold. When manufacturing GI-type plastic optical fibers using CYTOP, refractive index distribution is generally introduced through dopant technology. However, when a plastic optical fiber is manufactured by applying a dopant such as CTFE (chlorotrifluoroetylene), which has an effect of significantly lowering the Tg of the host polymer, to CYTOP, a host polymer having a relatively low Tg, the final Tg of the optical fiber base material and the optical fiber is 90 It is below C, which impairs time and temperature stability, leading to serious limitations in most fiber optic applications.

Asahi glass Co., on the other hand, proposed a fluorine-based polymer having the following chemical structure as a material to be applied to a graded index (GI) plastic optical fiber.

In the formula, l is 0-5, m is 0-4, n is 0-1, l + m + n is 1-6, o, p, q are each independently 0-5, o + p + q is 1-6, R, R ₁ , R ₂ are each independently F or CF ₃ , X ₁ , X ₂ are each independently F or Cl.

In addition to the fluorine-based polymer, 2,2-bistrifluoromethyl-4,5-difluoro-1,3-diosol (2,2-bistrifluorometyl-4,5-, named Teflon AF developed by Dupont) A copolymer of difluoro-1,3-dioxole (PDD) and tetrafluoroethylene may be exemplified. Specifically, the copolymer has a structure such as the following Chemical Formula 5.

However, according to the results presented at the 2001 International Plastic Optical Fiber Conference, the material is reported to have a high crystal loss due to some determinants.

The inventors of the present invention have completed the present invention by discovering that the fluorine-substituted polymer shown in US Pat. No. 5,498,682 by Ausimont is used as a material of plastic optical fiber and has no light scattering and improved heat resistance in the near infrared region.

That is, the present invention relates to a plastic optical fiber made of a fluorine-substituted polymer represented by the following formula (6).

[Formula 6]

Wherein R _F is a linear or branched perfluoroalkylic radical of 1 to 5 carbons, X ₁ , X ₂ are each independently F or CF ₃ , and n is a real number of 0.4 to 1;

1 is a view showing a refractive index distribution of the optical fiber manufactured by Example 1 of the present invention.

Hereinafter, the present invention will be described in more detail.

In the present invention, the fluorine-substituted polymer applied as the material of the plastic optical fiber is represented by the following formula (6).

Wherein R _F is a linear or branched perfluoroalkylic radical of 1 to 5 carbons, X ₁ , X ₂ are each independently F or CF ₃ , and n is a real number of 0.4 to 1;

In the polymer, R _F is preferably -CF ₃ .

In the polymer, the molar ratio of the dioxol monomer and the tetrafluoroethylene monomer is in the range of 10: 0 to 4: 6 because the amorphous and thermal properties of the dioxol monomer are less than 40%.

In preparing the base material for plastic optical fiber using the copolymer as described above, it can be applied regardless of the GI type or step index type optical fiber.

On the other hand, when manufacturing a GI-type plastic optical fiber, the dopant used to form the refractive index distribution has to satisfy various conditions in the characteristics of the host polymer used. Typical dopant selection conditions are that the dopant should have a high affinity with the copolymer, be non-volatile, have a high boiling point because diffusion and withdrawal of the base material is performed above the Tg of the copolymer during the preparation of the base material. There are conditions such as higher than the refractive index.

When using the polymer of Formula 6 as the host polymer as in the present invention, specifically, perfluoro-fluorene, perfluorobenzyltetralin, poly (trifluoro-chloroethylene ) (Poly (trifluoro-chloroethylene) oil), perfluoro-polyether oil (Krytox), 1,1,3,5,6-pentachloro-nonafluorobenzene (1,1 , 3,5,6-pentachloro-nonafluorobenzene) and the like may be used as the dopant, preferably perfluoro-polyether oil or perfluorobenzyltetrarin, and more preferably perfluorobenzyltetra Use lean.

In case of using perfluorobenzyltetrarin as a dopant, since perfluorobenzyltetrarin is a true solvent for the fluorine-substituted polymer of Chemical Formula 6, dopant is easily diffused and purple in terms of specific gravity. Luorobenzyl tetralin is 2.049 g / cm ³ and the fluorine-substituted polymer is 1.780 g / cm ³ has the advantage that the refractive index distribution can be easily formed by diffusion of the dopant in the molten state by centrifugal force.

As a method for diffusing the dopant into the polymer to form a refractive index distribution, various known methods can be applied without limitation, and the method described in JP-A-8-3344634 can be referred to.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples are for the purpose of explanation and are not intended to limit the present invention.

Fluorine-substituted polymers used in the examples were 2,2,4-trifluoro-5-trifluoromethoxy-1,3-diosol (TTD) and tetrafluoroethylene (TFE), which are commercially available from Ausimont. As a copolymer of, a compound having physical properties as shown in Table 1 below was used.

Copolymer TTD molar ratio Tg (℃) Melt viscosity Intrinsic viscosity A 78 141 600 28 B 76 125 - 36 C 67 119 - 55

[Measurement of physical properties]

* TTD molar ratio: measured by NMR

* Intrinsic Viscosity: ASTM D 2857 (FLUORINENT FC 75 Solvent)

* Tg: DSC method (Perkin-Elmer DSC-7 differential scanning calorimeter)

* Melt Viscosity: ASTM D 3835

Example 1

50 g of Copolymer A of Table 1 was placed in a 4 cm diameter glass tube and rotated at 270 rpm for 6 hours at 270 ° C. to prepare a hollow tube. Subsequently, perfluorobenzyltetrarin was added to the hollow as a dopant, and then rotated at a speed of 4,000 rpm for 8 hours at a temperature of 200 to 220 ° C. to allow diffusion according to specific gravity. The prepared base material was cooled to room temperature to obtain a GI type plastic optical fiber base material having a diameter of 4 cm.

Example 2

50 g of the copolymer B of Table 1 was placed in a 4 cm diameter glass tube and rotated at 270 ° C. at 6,000 rpm for 6 hours to prepare a hollow tube. Subsequently, perfluorobenzyltetrarin was added to the hollow as a dopant, and then rotated at a speed of 4,000 rpm for 6 hours at a temperature of 200 to 220 ° C. to allow diffusion according to specific gravity. The prepared base material was cooled to room temperature to obtain a GI type plastic optical fiber base material having a diameter of 4 cm.

Example 3

50 g of the copolymer C of Table 1 was placed in a 4 cm diameter glass tube and rotated at 270 rpm for 6 hours at 270 ° C. to prepare a hollow tube. Subsequently, perfluorobenzyltetrarin was introduced into the hollow as a dopant, and then rotated at a speed of 4,000 rpm for 3 hours at a temperature of 200 to 220 ° C. for diffusion according to specific gravity. The prepared base material was cooled to room temperature to obtain a GI type plastic optical fiber base material having a diameter of 4 cm.

The Tg of the optical fibers manufactured in Examples 1 to 3 was measured and shown in Table 2 below. In addition, the refractive index distribution of the base material prepared in Example 1 was measured by confocal Raman spectroscopy and shown in FIG. 1. At this time, a 20mW helium-neon laser (632.8nm) was used, and the Raman scattering method was captured by an Olympus BH microscope while the pinhole was set to 50um.

Perfluolovenzyltetraline content Optical fiber optical loss Average Tg (℃) of Base Material Example 1 20 wt% 25dB / km 120 Example 2 20 wt% 28 dB / km 109 Example 3 20 wt% 30 dB / km 90

[Measurement of physical properties]

* Tg: measured at 20 ℃ / min standard heating rate using Perkin-Elmer DSC-7

* Light loss: After drawing the base material into the optical fiber and measuring it by the cut-back method with 850nm light source

In the present invention, by applying a fluorine-substituted polymer as an optical material can provide a plastic optical fiber with improved transmission and heat resistance.

Claims (5)

Plastic optical fiber consisting of a fluorine-substituted polymer represented by the formula (6). [Formula 6] Wherein R _F is a linear or branched perfluoroalkylic radical of 1 to 5 carbons, X ₁ , X ₂ are each independently F or CF ₃ , and n is a real number of 0.4 to 1; 2. The plastic optical fiber according to claim 1, wherein the plastic optical fiber has a step index type. The plastic optical fiber according to claim 1, wherein the plastic optical fiber is a graded index type having a refractive index distribution formed by a dopant. The method of claim 3, wherein the dopant is perfluoro-fluorene, perfluorobenzyltetralin, poly (trifluoro-chloroethylene) oil (poly (trifluoro-chloroethylene) oil ), Perfluoro-polyether oil (Krytox), or 1,1,3,5,6-pentachloro-nonafluorobenzene (1,1,3,5,6-pentachloro- plastic optical fiber, characterized in that nonafluorobenzene) is used. 4. The plastic optical fiber according to claim 3, wherein perfluorobenzyltetrarin is used as the dopant.