JPH0527126A - Plastic optical fiber - Google Patents

Abstract

PURPOSE:To improve mechanical characteristics, workability, and optical characteristics by using a specified polycarbonate as the core material. CONSTITUTION:The core material consists of a polycarbonate which is a single polymer of polycarbonate comprising the recurring unit expressed by formula I as the main chain and has 25000-45000 weight mean mol.wt. to styrene standard and >=165 deg.C glass transition temp. This polycarbonate is obtd. by phosgene method, for example, by condensing phosgene oligomer of bisphenol AF. The solvent used in the phosgene condensation is methylene chloride, cholorobenzene, trichloroethylene, etc. As for the oxygen coupling agent, sodium hydroxide, potassium hydroxide, etc., are used. The catalyst to promote this condensation is, for example, tertiary amine, quaternary amine, etc., however, it is preferable to promote the synthesization without catalyst considering the decrease in optical characteristics during forming.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low loss plastic optical fiber having high heat resistance and excellent processability and mechanical properties.

[0002]

2. Description of the Related Art Conventionally, an optical fiber is made of inorganic glass and has been widely used for signal transmission for long distance transmission. In recent years, plastic optical fibers have been inferior in transmission loss to conventional inorganic glass optical fibers, but have been widely used for electronic devices because they are resistant to bending, are not easily broken, are lightweight, and are easy to handle.

In many of the plastic optical fibers which have been put into practical use at present, the core material is composed of polymethylmethacrylate having a good light transmission property, but the heat resistance temperature of polymethylmethacrylate is about 100.degree. Therefore, it cannot be used as a sensor in a microwave oven or for transmitting a control signal in an automobile engine room.

Therefore, various attempts have been made to improve the heat resistant temperature of the plastic optical fiber. For example, a method of copolymerizing polymethylmethacrylate and maleic anhydride, a method of copolymerizing methylmethacrylate and N-arylmaleimide, a method of imidizing a part of polymethylmethacrylate (JP-A-60-184212, JP-A-60-18509) and the like have been proposed.

Also, instead of polymethylmethacrylate,
Studies have been conducted on the use of polycarbonate (JP-A-57-46204 and JP-A-61-6604).
issue). Further, among the polycarbonates, studies have been made on a plastic optical fiber having a core material of polycarbonate made of bisphenol AF, bisphenol Z, or the like having a higher glass transition point than ordinary bisphenol A-based polycarbonates (Japanese Patent Laid-Open No. 64-19308).
No. 64-28602).

[0006]

However, the method of modifying polymethylmethacrylate has problems that heat resistance is insufficient and production efficiency is remarkably reduced. Further, the plastic optical fiber using a polycarbonate made of bisphenol A as a core material has a heat resistance of about 125 ° C. and cannot withstand the high temperature as in the engine room of an automobile.

Further, a polycarbonate homopolymer using bisphenol AF as a raw material was examined as in Example 4 of JP-A-64-19307, but the glass transition point was 180.
Polycarbonates above ℃ have a weight average molecular weight of 600
Therefore, it is necessary to perform molding at a high temperature of about 270 ° C., and there is a problem that the transmission loss increases due to decomposition and coloring during molding.

[0008]

[Means for Solving the Problems] The above-mentioned problems are

[Chemical 2] In a polycarbonate homopolymer consisting of repeating units of, the weight average molecular weight based on styrene is 25,000.
It was solved by a plastic optical fiber having a glass transition temperature of 165 ° C. or higher in the range of ˜45,000.

This polycarbonate is bisphenol A
Condensation of phosgenated oligomers of F, for example, from the phosgene process. The weight average molecular weight can be controlled within the above range by the stirring speed during the condensation, the reaction time, and the amount of sodium hydroxide.

Examples of the solvent used in this phosgenation condensation reaction include methylene chloride, chlorobenzene and trichloroethylene, and examples of the oxygen binding agent include sodium hydroxide and potassium hydroxide. Further, as a catalyst for promoting this condensation reaction, a tertiary amine,
Examples thereof include quaternary amines, but it is better to synthesize them without a catalyst in consideration of deterioration of optical characteristics during molding or heat resistance of a molded plastic optical fiber.

In this way, the molecular weight is 25,000-45.
000 polycarbonate. Weight average molecular weight is 2
If it is lower than 5000, there is a problem with physical strength,
If it exceeds 0, a high temperature of 270 ° C or higher is required at the time of molding,
The optical characteristics of the obtained plastic optical fiber are degraded.

The glass transition point is 165 ° C. or higher, preferably 170 ° C. or higher. The upper limit depends on the molecular weight, the terminal group, or the state of the molecular chain, and is preferably 177 ° C or lower. In the case of polycarbonate having a glass transition point of 165 ° C. or lower at the above-mentioned molecular weight, not only the heat resistance is deteriorated due to the deformation of the obtained plastic optical fiber, but also the initial optical characteristics of the molded plastic optical fiber are deteriorated. Or, it causes deterioration of mechanical properties.

The decrease in the glass transition point may be due to contact between the solvent of the polycarbonate and the alcohol, increase in the molecular weight distribution, side reaction or the like. Reaction control and post-reaction treatment must be carried out so as not to cause these problems.

The polycarbonate thus obtained has a refractive index of 1.50 to 1.51. As a polymer used for the sheath layer, the refractive index is 0.01% or more higher than the above-mentioned refractive index. Any polymer having a high light transmittance may be used, but a resin having heat resistance of 150 ° C. or higher is preferable.

As the above-mentioned sheath material, a fluorine-based resin (for example, a homopolymer or a copolymer of tetrafluoroethylene, vinylidene fluoride, propylene hexafluoride, etc.), a fluorinated acrylic resin, and an aliphatic or aromatic main chain Ring-containing fluororesins), polymethylpentene, imidized or dehydrated methacrylic acid polymers, polymer silicone resins of long-chain acrylic compounds, and the like.

The above-mentioned polymer is formed into fibers by a conventional double spinning method, but it must be formed at about 250 ° C. in order to minimize the loss of the obtained fibers. Further, it is preferable to remove air (oxygen) contained in the obtained polycarbonate and then perform molding under an inert gas.

[0017]

EXAMPLES The present invention will be described in more detail based on examples. In the examples, the molecular weight means the weight average molecular weight unless otherwise specified.

Example 1 30% in a container equipped with a stirrer, thermometer and gas inlet
400 g of sodium hydroxide and 3.5 liters of distilled water were added and mixed well. 1 mol of bisphenol AF was added thereto with stirring, and 4 liters of methylene chloride was further added. Then, 1.35 mol of phosgene was introduced at 25 ° C. and reacted for 1 hour to form an oligomer, which was further hydroxylated at 25 ° C. by 30%. 700 g of an aqueous sodium solution was added and stirred sufficiently.
The stirring was stopped when the molecular weight of the polycarbonate reached about 35,000 (based on styrene). The reaction time was 5 hours. The obtained aqueous phase and organic phase were separated, and the organic phase was thoroughly washed with 0.02N aqueous sodium hydroxide solution and then washed with 0.1N hydrochloric acid. After washing, methylene chloride was removed to obtain a white flake polycarbonate. The refractive index was 1.51, and the glass transition point by differential thermal analysis was 174 ° C. The molecular weight distribution by GPC was 1.49.

The obtained polycarbonate is selected as an inner layer (core material) and an outer layer (sheath material) of ethylene-tetrafluoroethylene copolymer, and the polycarbonate is heated at 120 ° C.
After sufficiently vacuum drying, the two resins were supplied to a double extruder under argon and pulled out from a double spinning nozzle to obtain a plastic optical fiber. The temperature of the spinning head was 250 ° C., the core diameter was 0.95 mm, and the clad thickness was 0.03 mm. The transmission loss of the obtained plastic optical fiber is 800 dB / km (770 mm)
850 dB / km after heat treatment at 140 ° C. for 1 week
(770 mm). The mechanical strength of the fiber was sufficient, and the elongation was 50% or more.

Example 2 30% in a container equipped with a stirrer, thermometer and gas inlet
400 g of sodium hydroxide and 3.5 liters of distilled water were added and mixed well. 1 mol of bisphenol AF was added thereto with stirring, and 4 liters of methylene chloride was further added. Then, 1.35 mol of phosgene was introduced at 25 ° C. and reacted for 1 hour to form an oligomer, which was further hydroxylated at 25 ° C. by 30%. 700 g of an aqueous sodium solution was added and stirred sufficiently.
The stirring was stopped when the molecular weight of the polycarbonate reached about 45,000 (based on styrene). The reaction time was 6 hours. The subsequent treatment was the same as in Example 1. The obtained polycarbonate had a refractive index of 1.51, and a glass transition point by differential thermal analysis of 176 ° C. The obtained polycarbonate was selected as an inner layer and an ethylene-tetrafluoroethylene copolymer was selected, and the polycarbonate was sufficiently vacuum dried at 120 ° C., and then these two resins were supplied to a double extruder under argon to perform double spinning. A plastic optical fiber was obtained by pulling out from a nozzle. The temperature of the spinning head was 255 ° C., the core diameter was 0.95 mm, and the clad thickness was 0.03 mm. The transmission loss of the obtained plastic optical fiber is 900 dB / km (770 mm), and after heat treatment at 140 ° C. for 1 week, it is 930 dB / km (7 mm).
70 mm). The mechanical strength of the fiber was sufficient, and the elongation was 50% or more.

Example 3 30% in a container equipped with a stirrer, thermometer and gas inlet
400 g of sodium hydroxide and 3.5 liters of distilled water were added and mixed well. 1 mol of bisphenol AF was added thereto with stirring, and 4 liters of methylene chloride was further added. Then, 1.35 mol of phosgene was introduced at 25 ° C. and reacted for 1 hour to form an oligomer, which was further hydroxylated at 25 ° C. by 30%. 650 g of an aqueous sodium solution was added and stirred sufficiently.
The stirring was stopped when the molecular weight of the polycarbonate reached about 27,000 (based on styrene). Reaction time is 4.5
It was time. The obtained aqueous phase and organic phase were separated, and the organic phase was thoroughly washed with 0.02N aqueous sodium hydroxide solution and then washed with 0.1N hydrochloric acid. After washing, methylene chloride was removed to obtain a white flake polycarbonate. The refractive index was 1.51, and the glass transition point by differential thermal analysis was 167 ° C.

Ethylene-tetrafluoroethylene copolymer was selected as the inner layer and the outer layer of the obtained polycarbonate, and the polycarbonate was sufficiently vacuum dried at 120 ° C., and then these two resins were fed to a double extruder under argon. Then, a plastic optical fiber was obtained by pulling out from the double spinning nozzle. The temperature of the spinning head is 250 ° C, the core diameter is 0.95 mm, and the clad thickness is 0.03 mm.
Met. The transmission loss of the obtained plastic optical fiber is 800 dB / km (770 mm), 140 ° C. 1
It was 900 dB / km (770 mm) after the weekly heat treatment. The mechanical strength of the fiber was sufficient, and the elongation was about 50%.

Comparative Example 1 30% in a container equipped with a stirrer, thermometer and gas inlet
400 g of sodium hydroxide and 3.5 liters of distilled water were added and mixed well. 1 mole of bisphenol AF there
After adding 4 liters of methylene chloride, 2
1.5 moles of phosgene was introduced at 5 ° C. and reacted for 1 hour to give an oligomer. Further, 900 g of a 35% sodium hydroxide aqueous solution was added, and the mixture was sufficiently stirred. The stirring speed was 1.4 times that of the example. The molecular weight of polycarbonate is about 3
When it reached 0000, the stirring was stopped. The reaction time was 4.5 hours. The subsequent treatment was the same as in Example 1. The refractive index was 1.51, and the glass transition point by differential thermal analysis was 162 ° C.

When the molecular weight distribution was investigated, M _W / M _N
= 2.20. An ethylene-tetrafluoroethylene copolymer was selected as the inner layer and the outer layer of the obtained polycarbonate, and the polycarbonate was sufficiently vacuum dried at 120 ° C., and then these two resins were supplied to a double extruder under argon, and 2 A plastic optical fiber was obtained by pulling out from a double spinning nozzle. The temperature of the spinning head is 25
0 ℃, core diameter 0.98mm, cladding thickness 0.05m
It was m. The transmission loss of the obtained plastic optical fiber is 960 dB / km (770 mm), 140 ° C.
The transmission loss after heat treatment for 1 week was 1100 dB / km.

Comparative Example 2 The polycarbonate obtained by the method of Example 1 was reprecipitated in ethanol and dried to obtain a polycarbonate flake. Refractive index is 1.51, glass transition point by differential thermal analysis is 16
It was 2 ° C. As a result of measuring the molecular weight by GPC, the molecular weight was 30,000 and M _W / M _N was 2.19.

Ethylene-tetrafluoroethylene copolymer was selected as the inner layer and outer layer of the obtained polycarbonate, and the polycarbonate was sufficiently vacuum dried at 120 ° C., and then these two resins were fed to a double extruder under argon. Then, a plastic optical fiber was obtained by pulling out from the double spinning nozzle. The temperature of the spinning head is 250 ° C, the core diameter is 0.95 mm, and the clad thickness is 0.03 mm.
Met. The transmission loss of the obtained plastic optical fiber is 1000 dB / km (770 mm), 140 ° C.
The transmission loss after heat treatment for 1 week was 1100 dB / km. Comparative Example 3 30% in a container equipped with a stirrer, thermometer and gas inlet
400 g of sodium hydroxide and 3.5 liters of distilled water were added and mixed well. 1 mol of bisphenol AF was added thereto with stirring, and 4 liters of methylene chloride was further added. Then, 1.35 mol of phosgene was introduced at 25 ° C. and reacted for 1 hour to form an oligomer, which was further hydroxylated at 25 ° C. by 30%. 700 g of an aqueous sodium solution was added and stirred sufficiently.
The stirring was stopped when the molecular weight of the polycarbonate reached about 55,000 (based on styrene). The reaction time was 7 hours. The obtained aqueous phase and organic phase were separated, and the organic phase was thoroughly washed with 0.02N aqueous sodium hydroxide solution and then washed with 0.1N hydrochloric acid. After washing, methylene chloride was removed to obtain a white flake polycarbonate. The refractive index was 1.51, and the glass transition point by differential thermal analysis was 178 ° C.

Ethylene-tetrafluoroethylene copolymer was selected as the inner layer and the outer layer of the obtained polycarbonate, the polycarbonate was sufficiently vacuum dried at 120 ° C., and the two resins were supplied to a double extruder under argon. Then, a plastic optical fiber was obtained by pulling out from the double spinning nozzle. The temperature of the spinning head is 20 ° C, the core diameter is 0.95 mm, and the clad thickness is 0.03 mm.
Met. The transmission loss of the obtained plastic optical fiber is 1000 dB / km (770 mm), 140 ° C.
It was 1050 dB / km after heat treatment for 1 week. Also, the mechanical strength of the fiber is sufficient, and the elongation is 50%.
That was all.

Comparative Example 4 30% in a container equipped with a stirrer, a thermometer and a gas inlet.
400 g of sodium hydroxide and 3.5 liters of distilled water were added and mixed well. 1 mol of bisphenol AF was added thereto with stirring, and 4 liters of methylene chloride was further added. Then, 1.35 mol of phosgene was introduced at 25 ° C. and reacted for 1 hour to form an oligomer, which was further hydroxylated at 25 ° C. by 30%. 700 g of an aqueous sodium solution was added and stirred sufficiently.
When the molecular weight of the polycarbonate reached about 23000 (based on styrene), the stirring was stopped. Reaction time is 3.5
It was time. The obtained aqueous phase and organic phase were separated, and the organic phase was thoroughly washed with 0.02N aqueous sodium hydroxide solution and then washed with 0.1N hydrochloric acid. After washing, methylene chloride was removed to obtain a white flake polycarbonate. The refractive index was 1.51, and the glass transition point by differential thermal analysis was 163 ° C. The obtained polycarbonate had almost no strength and could not be made into fibers.

[0029]

The plastic optical fiber using the specific polycarbonate of the present invention as the core material is excellent in heat resistance, mechanical properties and workability, and is also excellent in optical properties in terms of low loss.

Claims (1)

Claims: 1. As a core material, the main chain is A homopolymer of polycarbonate having a weight average molecular weight of 25000 to styrene.
Is in the range of 45,000 and has a glass transition temperature of 16
A plastic optical fiber characterized by using polycarbonate having a temperature of 5 ° C. or higher.