JPH02105102A - Plastic optical fiber - Google Patents

Abstract

PURPOSE:To lower a transmission loss and to improve long-term heat resistance and stability by confining the ratio at which the terminal of a polymer to be used for a fiber material is a phenolic OH group to <=0.02wt.% as the ratio of OH when determined by a TiCl4 method. CONSTITUTION:The ratio at which the terminal of the polymer to be used for the fiber material of the plastic optical fiber formed by using the polymer essentially of polycarbonate as the fiber material and a resin having the refractive index lower than the refractive index of the fiber material as the sheath material is the phenolic OH group is confined to <=0.02wt.% as the ratio of the OH group determined by the TiCl4 method. The plastic optical fiber produced in such a manner less increased in transmission loss over a visible light to near IR region and exhibits the extremely outstanding long-term heat resistance even if the fiber is kept heated for 2,000 hours at 120 deg.C. The stable plastic optical fiber which is less increased in the loss in the visible to near region even after the long-term use at a high temp. is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a plastic optical fiber that has low transmission loss from the visible light region to the near-infrared region and has excellent long-term heat resistance and stability.

(Conventional technology) Compared to silica-based optical fiber, glass optical fiber has
High flexibility, large diameter and high numerical aperture, ll
Due to its ease of surface processing and connection, it has begun to be applied to fields such as internal wiring and short-distance communications.

Glass optical fibers that have been put into practical use include the following.

■Polymethyl methacrylate is used as the core material, and the sheath material is made of pynylidene fluoride-tetrafluoroether/copolymer or 7-methacrylate copolymer.

■The core material is polystyrene and the sheath material is polymethyl methacrylate.

In addition, as a heat-resistant plastic optical fiber that can be used at high temperatures of 100°C or higher, the core material has a glass transition point of approximately 1.
50℃ / IJ carbonate is being considered. Resin for sheath material □% 1986-32004, 1986-6604, 1987 JP-A
1-22513, JP-A-62-118307, etc., poly-4-methylpentene-1,7-methacrylate copolymers, vinylidene fluoride copolymers, etc. have been disclosed. ing.

(Problems to be Solved by the Invention) Conventional plusbook optical fibers with a core material of polycarbonate suffer from an increase in transmission loss even when used at high temperatures of 120°C to 130°C for short periods; I can't watch it.

However, after 1000 hours or more, three colors were generated due to the progress of thermal deterioration, and there was a point where the loss gradually increased. This degree increases as the wavelength becomes shorter; in the window around 660 nm, it is 300 dB.
/A2+ or more, the loss increases.

(G!Means for solving the problem) As a result of intensive research to solve the above-mentioned problems, we found that the polycarbonate used for the core material has different heat resistance depending on the type of end group, and we found that It was discovered that polycarbonate containing phenolic OH groups tends to become discolored, and this is the main cause of increased transmission loss when exposed to high temperatures for long periods of time. Therefore, production of a plastic optical fiber having long-term heat resistance can be achieved by using polycarbonate (T-) whose terminal ends are mostly free of phenolic OH groups.

That is, the present invention provides a plastic optical fiber in which the core material is a polymer mainly composed of polycarbonate, and the sheath material is a resin with a lower refractive index than the core material. is Fe1 7-L O
The proportion of H groups is Ti07. The amount of OH when determined by the method is 0.0231 ft% or less.
A plastic optical fiber is provided.

Polycarbonates suitable for the core material include aromatic polycarbonates. Preferably, bisniphenol A polycarnate is used. In addition, copolymers of these polycarbonates and dioxy compounds such as 4,41-dioxyphenyl ether, p-xylene glycol, and 1,6-hexanediol, and copolymers with carbonate bonds or ester bonds. It is also possible to use a Peter bond copolymer having Further, the melt index is within the range of '0.5 to 20.9/10 minutes, and is preferably smaller than the melt index of the sheath material.

Polycarbonate is obtained by reacting bisphenol A and phosdan in a mixed solvent of an aqueous dispersion of sodium dichloromethane. The polycarbonate used for the plastic optical 7 eyeglass of the present invention must be completely free of demi and impurities in order to reduce transmission loss. For this purpose, the main raw materials such as bisphenol A and phosdan, solvents such as sodium hydroxide solution and dichloromethane, terminal stoppers such as ptsrl;-butylphenol, and washing water, nitrogen, and air must be removed through distillation, filter filtration, etc. It is necessary to remove demi-impurities by the following method. In addition, raw materials and solvents used for polymerization.
The ratio of the amount of the synthesis aid and the polymerization conditions must be properly controlled. Due to the effects of impurities in the polymerization tank, imbalances in the ratio of raw materials and terminal terminators, and fluctuations in polymerization conditions, hydrolysis of the intermediate, which is a competitive reaction, progresses while the normal reaction progresses, resulting in It is thought that the amount of low molecular weight polycarbonate having phenolic OH groups increases, resulting in products with poor mechanical strength and heat resistance. Furthermore, after polymerization, it is important to completely wash away remaining sodium hydroxide, salt, catalyst, etc. with water, and to evaporate dichloromethane. In addition, in order to remove low molecular weight components with a large amount of terminal groups, it is preferable to purify by a reprecipitation method or the like.

Next, the TiC method used to quantify the terminal phenolic OH group will be explained. This quantitative amount
Makromoleculars OhemLe
88 (i 9 (55) pp, 215~
The assay was carried out according to the quantitative method of Van A, Horbach et al., described in 231. In addition, the following solvents and reagents were used.

・Solvent Nidichloromethane Use a water content of o, o i% or less.

-T10j, solution: 40 Jil) Ttcj, and 0.5.
! i'+7) acetic acid and 11 dichloromethane KI.

- Acetic acid solution: 50 g of acetic acid t-11/dissolved in dichloromethane.

First, 50~200~ polycarbonate is dissolved in 10M dichloromethane. To this were added Ti0j, solution 10g and acetic acid solution 4d, and dichloromethane was further added so that the total amount was 25m. Then, the solution immediately turns orange red, so the extinction coefficient [α-1] of this solution is
Measurement was performed using 545 nm light from a mercury lamp. The formula for determining the extinction coefficient is shown below.

' = (10 g1o (Work 0/Work)] / dε: Extinction coefficient [cIn-1] A calibration curve representing the relationship between the extinction coefficient value and the OH weight in the 25M solution was determined.This graph is shown in FIG.

From the extinction coefficient of the polycarbonate solution and the calibration curve, 2
5. Determine the amount of 0111i contained in the Go solution, and from the ratio of this to the weight of the dissolved polycarbonate, determine the amount of phenolic O1
1 child% of H group was calculated.

If the proportion of phenolic OH groups exceeds 0.02% by weight, coloring will occur and the transmission loss at 120° C. will increase significantly. The preferred proportion of phenolic OH groups is 0.018% by weight or less, more preferably 0.01% by weight or less.
It is 5% by weight or less.

The sheath material used in the present invention may be any transparent resin that has a lower refractive index than the polycarbonate core material. More preferably, it has appropriate mechanical strength and is capable of adhering to polycarbonate. For example, polymers and copolymers such as fluoroalkyl acrylate, fluoroalkyl methacrylate, fluoroalkyl-α-fluoroacrylate, copolymers such as vinylidene fluoride, trifluoroethylene, tetrafluoroethylene, hexafluoropropylene, and polymethyl methacrylate. Prene r1 polymethyl methacrylate, poly-
4-methylpe/tene-1, etc., and JP-A-63-1423
Examples include the vinylidene fluoride-hexafluoroacetone copolymer described in No. 08.

The method for producing the plastic optical fiber of the present invention involves melting the core material and sheath material pellets in a clean environment, and forming a core-sheath structure using a special nozzle and two extruders. It is best to use the spinning method. The sheath is 2/1000 to 300/10 of the core diameter.
Coat to a thickness of about 0.00 to obtain stock grade. This bare wire has
To further increase heat resistance, cross-linked polyethylene, cross-linked 11It
It can also be put to practical use as a coater by applying several layers of heat-resistant coatings such as vinyl, polypropylene, polyvinylidene fluoride, and nylon.

The plastic optical fiber of the present invention produced in this manner is extremely stable, with only a small increase in loss in the visible to near-infrared range, even when used for long periods of time at high temperatures.

(Examples) Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way. In addition, each physical property value was measured as follows.

(1) Transmission loss Fiber loss spectrometer yp-8 manufactured by Operax Co., Ltd.
89, and measured by the cutback method of 12 ffl-2 m.

(2) Melt Index Toyo Seiki Co., Ltd.! ! ! Using a melt indexer, measurements were made under the conditions of ASTM-1238 test temperature 230°C, load 3.8, and die inner diameter 2.0955 m.Example 1 High purity bisphenol A of 4569 and p of 9.59.
-tart-butylphenol and filtered pure water 15
In addition to #00, filtered nitrogen was blown into the reactor while stirring, and the oxygen tube inside the reaction tank was removed. Next, 45% hydroxide) IJum aqueous solution 335 II, dichloromethane 1000. F was added and high purity phosgene 2379 was blown in over 60 minutes while keeping the temperature at 25°C.

After the blowing of phosdan was completed, 0.1 of triethylamine was added, and stirring was continued for an additional 2 hours to advance the reaction.

After the reaction was completed, the dichloromethane solution containing polycarbonate was thoroughly washed with filtered pure water to thoroughly remove remaining impurities such as salt and alkali. After that, hemethane, which is a poor solvent, is added to reprecipitate the polycarbonate.
At the same time, low molecular weight components were also cut. After the solvent was blown off, the mixture was molded into pellets using a vented extruder.

T101. When the proportion of terminal phenolic OH groups was measured by the method, it was found to be 0.005% by weight. Moreover, the melt index was 5 g/10 minutes.

Using this polycarbonate as a core and poly-4-methylpentene-1T- as a sheath, the outer diameter was 1000 μm, the thickness of the sheath was 1
A bare plastic optical fiber having a diameter of 0 μm was obtained. In addition, commercially available water-crosslinked polyethylene Nippon Unicar Co., Ltd. *
rsN-150J was multi-machined to have a sheath diameter of 2.211IE, put into a cold water tank for 20 hours at 65° C. to carry out a crosslinking reaction, and a plastic optical fiber vania-ft- was produced.

The transmission loss of this code is 50 nm at the wavelength of light 770 nm.
0 dB/A2l5 5204B/Ax at 660 nm
Met. Put this cord in a thermostat at 120℃ and
When the transmission loss was measured after 00 hours, it was 770 nm.
540 dB/bs at 620 dB/bs at 660 nm
b, and was very stable.

Example 2 Commercially available polycarbonate (“Panlite JI, -122
5. Dissolved in t-dichloromethane (manufactured by Yojin Kasei Co., Ltd.),
The purification method of reprecipitation in acetone and separation from the solvent was repeated several times to remove low molecular weight components.

The proportion of terminal phenolic OH groups in this polycarbonate is 0.012% by weight, and the melt index is! IM/10 minutes.

A core diameter of 1000 μm, a sheath diameter of 2.2
A plastic optical fiber cord of m was fabricated.

The transmission loss of this code is 650 d at 770nffI
B/IaR was 750 dB/kR at 1660 nm.

I put this cord in a thermostat at 120℃ and measured the transmission loss after 2000 hours.
0 aB/Ax, 15 (880 dB at S Onm
/b and was very stable.

Example 3 The proportion of phenolic OH groups in "Nipiron" H4000 (manufactured by Mitsubishi Gas Chemical Co., Ltd.) was measured and found to be 0.01.
5% by weight, and the melt index is 14fi/10
It was a minute.

When a plastic optical fiber cord was produced using this polycarbonate as a core material in the same manner as in Example 2, the transmission loss was 670 at 770 nm (LB/b% 660 n
l! I was 7754B/kR. This knee V is 12
When placed in a constant temperature bath at 0°C and measured for transmission loss after 2000 hours, it was 720 dB/hs660 at 770 nm.
It is 910 clB/b in nm and is stable.

Comparative Example 1 Commercially available polycarnate (Panlite J AD-550
3, manufactured by Yojin Kasei Co., Ltd.), the proportion of terminal phenolic OH groups was measured and was 0.050% by weight, and the melt index was 16! l/'I was 0 minutes.

A plastic optical fiber cord having a bare wire diameter of 1000 μm and a sheath diameter of 2.2N was manufactured in the same manner as in Example 1 except that this polycarbonate was used as the core.

The transmission loss of this knee P is 930 nm at a wavelength of 770 nm.
dB/kJn, 11504B/b at 660 nm, but when the transmission loss was measured after heating at 120°C for 2000 hours, it was 1050 dB/bs at 770 nm.
It increased to 1800 dB/b at 660 nm.

(Effect of the invention) The plastic optical fiber of the present invention has a temperature of 200°C at 120°C.
Even when heated for 0 hours, the increase in transmission loss is small over the visible light region to near-infrared region, and it exhibits excellent long-term heat resistance. Therefore, the plastic optical fiber of the present invention can be applied to parts that require long-term heat resistance and Φ stability, such as the engine room of an automobile.

[Brief explanation of drawings]

FIG. 1 shows a calibration curve used for quantifying the terminal phenolic OB group in the present invention. Patent applicant: Asahi Kasei Industries, Ltd.

Claims (1)

[Claims] In plastic optical fibers whose core material is a polymer mainly composed of polycarbonate and whose sheath material is a resin with a lower refractive index than the core material, the proportion of polymers used in the core material whose terminal ends are phenolic OH groups. A plastic optical fiber characterized in that the amount of OH is 0.02% by weight or less when determined by the TiCl_4 method.