JPH06347650A - Plastic light transmission body and its production - Google Patents

Abstract

PURPOSE:To provide a plastic transmission body having a high heat resistance, small transmission loss, small thermal shrinkage at a high temp. and lowered increase rate of the transmission loss. CONSTITUTION:The core part of this plastic transmission body, for example, a plastic optical fiber, consists of polycarbonate. The endothermic peak at the time when the polycarbonate in the core part of the plastic transmission body is subjected to a differential thermal analysis at 10 deg.C/min heating up rate exists in the 100 to 200 deg.C range and the endothermic quantity thereof is >=1.5mJ/mg.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic optical transmission body having a small transmission loss and improved heat resistance, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Plastic optical fibers are optical transmitters which are flexible, lightweight and easy to process at terminals, and are expected to be developed and used as signal transmission lines for automobiles and electronic equipment. ing. Among them, the transmission loss of acrylic plastic optical fiber is 300d.
B / km is low and loss is low, but heat resistance is around 85 ° C., which limits the range of use. On the other hand, a polycarbonate plastic optical fiber has heat resistance higher than that, but the heat resistance is about 125 ° C., which is still insufficient as an optical transmission line used in an automobile engine room or the like.

[0003]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a plastic optical transmission body having a low transmission loss and a high heat resistance. Another object of the present invention is to provide a plastic optical fiber which can improve the heat resistance of the conventional plastic optical fiber and expand the range of application of the fiber. Further, an object of the present invention is to provide a method for producing a plastic optical transmission body having a small transmission loss and high heat resistance, for example, providing a method for producing a plastic optical fiber having improved heat resistance. is there.

[0004]

In order to achieve the above object, the inventors of the present invention are keenly aware of the heat resistance of a plastic optical transmission body, especially a plastic optical fiber having a polycarbonate core material when the core material is a thermoplastic resin. As a result of the study, it is possible to improve the heat resistance of the resin by pre-heating the core layer of the polycarbonate at a predetermined temperature below the glass transition temperature of the resin, and the plastic optical fiber after this heat treatment has a low transmission loss. It was found that the increase in transmission loss was small even at high temperatures. The present invention is based on this finding.
That is, the present invention is (1) a plastic optical transmission body having a core portion made of polycarbonate, wherein the polycarbonate of the core portion has an endothermic peak of 100 ° C. or more when subjected to a differential thermal analysis at a heating rate of 10 ° C./min. Exists in a temperature range of 200 ° C or less and has an endothermic amount of 1.5 mJ / m
A plastic optical transmission medium characterized by being a polycarbonate having a weight of g or more, (2) A plastic optical transmission medium according to item (1), wherein the plastic optical transmission medium is a plastic optical fiber. When manufacturing a plastic optical transmission body whose core portion is made of polycarbonate, at least 8 ° C. is lower than the glass transition temperature of the polycarbonate forming the core portion by 10 ° C. or more.
A method of manufacturing a plastic optical transmission medium, characterized in that the core portion is heat-treated for a period of time, and (4) the plastic optical transmission medium according to (3), wherein the plastic optical transmission medium is a plastic optical fiber. A method of manufacturing a body is provided.

The optical transmission medium in the present invention means a light wave, a signal,
It means one used as an optical waveguide for propagating an image or the like, and specifically includes an optical fiber, a light guide, an optical fiber sensor and the like, as well as a connecting portion for these and an optical coupler. The shape is not particularly limited, and the cross section of the core may be circular or rectangular. Next, the present invention
An optical fiber, which is a typical optical transmission body, will be described as an example. The polycarbonate of the core layer that constitutes the plastic optical fiber has an endothermic peak at 100 ° C or more and 200 ° C or less when the differential thermal analysis is performed at a temperature rising rate of 10 ° C / min, and the endothermic amount is 1.5 mJ / mg. Must be above. The position of this endothermic peak almost depends on the glass transition temperature of the resin, but this endothermic peak appears at a position higher by 1 to 20 ° C. than the glass transition temperature of the resin constituting the core layer. A plastic optical fiber whose temperature is lower than 100 ° C has poor heat resistance, and the higher the temperature, the better.
Further, if it exceeds 200 ° C., the molding process of the resin becomes difficult. The plastic optical fiber preferably has an endothermic peak of the core layer at 130 ° C. or higher and 190 ° C. or lower, particularly preferably 135 ° C. or higher and 185 ° C. or lower. The endothermic amount at this endothermic peak is 1.5 mJ.
/ Mg or more. Heat absorption is 1.5 mJ /
This is because if it is less than mg, the heat resistance of the plastic optical fiber is not improved. Further, as a plastic optical fiber, the endothermic amount at the endothermic peak is preferably 2.0 mJ / mg or more, particularly preferably 2.5 mJ / mg.
It is more than mg. Polycarbonate is used as the thermoplastic resin for the core layer used in such a plastic optical fiber in consideration of the transmission loss and the glass transition temperature of the resin, and the polycarbonate has a large heat treatment effect. The polycarbonate is not particularly limited and may be any type. Specifically, in addition to polycarbonate A (a polycarbonate having bisphenol A and carbonyl as repeating units below), a carbonate precursor is added to the following dihydric phenol. Examples thereof include aromatic polycarbonates obtained by reaction and copolymers thereof.

The dihydric phenol includes 2,2-bis (4-hydroxyphenyl) propane (hereinafter referred to as bisphenol A), 2,2-bis (4-hydroxyphenyl) -1,1,1,3. 3,3-hexafluoropropane (hereinafter referred to as bisphenol AF), 1,1
-Bis (4-hydroxyphenyl) -1-phenylethane (hereinafter referred to as bisphenol AP), 9,9-bis (4-hydroxyphenyl) fluorene (hereinafter referred to as bisphenol FL), bis (4-hydroxyphenyl) Methane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 4,4-bis (4-hydroxyphenyl) heptane, 2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, bis (4-hydroxyphenyl) oxide, bis (3,5-dichloro-4-hydroxyphenyl) oxide, p, p'-dihydroxybiphenyl , 3,3'-
Dichloro-4,4'-dihydroxybiphenyl, bis (4-hydroxyphenyl) sulfone, bis (3,5-
Dimethyl-4-hydroxyphenyl) sulfone, resorcinol, hydroquinone, 1,4-dihydroxy-
2,5-dichlorobenzene, 1,4-dihydroxy-3
-Methylbenzene, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfoxide and the like. Examples of the carbonate precursor to be reacted with the above divalent phenol include phosgene and diphenyl carbonate.

The heat treatment of the plastic optical fiber may be performed after forming the clad layer on the core or may be performed on the core before forming the clad layer. The heat treatment temperature is lower than the glass transition temperature of the core layer resin by 10 ° C. or more, and preferably 10 ° C. lower than the glass transition temperature of the core layer resin.
The temperature is not lower than 50 ° C. and not higher than 50 ° C., particularly preferably not lower than 15 ° C. and lower than 40 ° C. lower than the glass transition temperature of the core layer resin. This is because if the heat treatment temperature is lower than the glass transition temperature and smaller than 10 ° C., the fiber shrinks, heat resistance cannot be improved, and the decrease in transmission loss is not reduced. Although not particularly limited, if the temperature is 50 ° C. or lower than the glass transition temperature, the effect of heat treatment is small and the productivity is poor, which is not preferable. The heat treatment conditions are, for example, 110 to 130 ° C. when the core portion is polycarbonate A (usually, the glass transition temperature is about 142 ° C.),
It is preferably about 110 to 125 ° C. In manufacturing a plastic optical fiber, the heat treatment is performed for 8 hours or more. The upper limit of the heat treatment time is not particularly limited, but the heat treatment is preferably performed for 20 to 200 hours, more preferably 30 to 180 hours. If the heat treatment time is insufficient, an endothermic peak does not appear and heat resistance is not improved, which is not preferable. As the clad layer of the plastic optical fiber, tetrafluoroethylene-hexafluoroethylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, ethylene-tetrafluoroethylene copolymer, fluorinated polymethylmethacrylate, Teflon AF ( Fluorine-based resins such as trade names (manufactured by Dyupon Co., Ltd.) and Cytop (trade names, manufactured by Asahi Glass Co., Ltd.), silicone resins, and imidized acrylic resins are used. The production of plastic optical fiber can be done according to the usual method,
For example, while continuously spinning the core, the outer periphery of the core may be coated with a clad layer in a later step, and the so-called double extrusion method or other method may be used. There is no limit in itself. In order to further reduce the transmission loss, a plastic optical fiber may be produced by forming a preform by using the heating decompression / pressurizing method disclosed in JP-A-4-124603 and then spinning the preform. In the present invention, also in the case of a plastic optical transmission body other than the plastic optical fiber, the same core as that described for the plastic optical fiber is used, and the manufacturing method of the core is also the same as that of the plastic optical fiber.
On the other hand, the points other than the core are the same as those of the conventional light guides, optical fiber sensors, and other optical transmitters, and the above-mentioned points can be followed by a conventional method.

[0008]

According to the method of manufacturing an optical transmission body of the present invention,
By performing heat treatment at a temperature lower than the glass transition point of the core layer resin by 10 ° C. or more after clad in the core or before clad, an optical transmission body having high heat resistance and small transmission loss can be prepared. Further, the plastic optical transmission article of the present invention has an endothermic peak above the glass transition temperature of the thermoplastic resin of the core layer, has a small heat shrinkage rate at high temperatures, and has a small increase in transmission loss. Therefore, the heat-resistant plastic optical transmission body of the present invention is not only a plastic optical fiber for propagating light waves, signals, images, etc., but particularly for heat resistance, for a light guide for transmitting illumination light from a light source, Automotive Optical LAN (Local Area Network), FA (Factory Automation) -L
It is preferably used in devices such as an AN system and an optical fiber sensor for confirming the position of an article in a factory at a high temperature, and has excellent effects.

[0009]

The present invention will be described in more detail based on the following examples, but the present invention is by no means limited to these examples. The parts in the examples represent parts by weight. The characteristics were measured by the following methods. -Transmission loss: A 660 nm LED was used as a light source and measured by the 5 m-1 m cutback method. -Differential thermal analysis: DSC RDC220 (manufactured by Seiko Denshi Kogyo Co., Ltd.) was used for measurement at a heating rate of 10 ° C / min. -Shrinkage rate The plastic optical fiber was cut into 10 cm, and the length after heat treatment at a predetermined temperature for 10 days was measured, and the shrinkage rate was calculated by the following formula.

[0010]

[Equation 1]

Example 1 Polycarbonate AD-9000TG (trade name, Polycarbonate A; Teijin Kasei Co., Ltd.) (glass transition temperature: 142 ° C.) was added as a core layer to the resin introducing passage of the plastic optical fiber spinning apparatus, and the head temperature was 245 ° C. Spun in.
A die is installed in the middle of spinning, a thermosetting silicone resin (trade name, X-38-091 HAB: manufactured by Shin-Etsu Chemical Co., Ltd.) is added to the die to form a clad layer, and then the die is further cured in a furnace below the die. It was Next, this was heat-treated at 120 ° C. for 2 days to obtain a target plastic optical fiber. The obtained plastic optical fiber has a core diameter of 0.9.
The outer diameter was 6 mm and the outer diameter was 1.02 mm. The transmission loss was 400 dB / km (660 nm: LED). The results of differential thermal analysis by DSC of the obtained plastic optical fiber are shown in FIG. 1. The endothermic peak appeared at 153 ° C. and the endothermic amount was 4.7 mJ / mg. When this plastic optical fiber was heated at 135 ° C for 1 month, the transmission loss was 630 dB / km (660 nm: LE
D). When the obtained plastic optical fiber was heat-treated at 135 ° C. for 10 days, the shrinkage rate of the fiber was 0.8%.

Comparative Example 1 A plastic optical fiber was prepared in the same manner as in Example 1 except that heat treatment was not performed at 120 ° C. after forming the cladding layer. The transmission loss of the obtained plastic optical fiber was 400 dB / km (660 nm: LED). The results of the differential thermal analysis by DSC of the obtained plastic optical fiber are shown in FIG. 2, but no endothermic peak was observed and an endothermic transition of glass transition temperature was observed at 142 ° C. When this plastic optical fiber was heated at 135 ° C for 1 month, the transmission loss was 1300 dB / km.
(660 nm: LED). When the obtained plastic optical fiber was heat-treated at 135 ° C. for 10 days, the shrinkage rate of the fiber was 5.4%.

Comparative Example 2 A plastic optical fiber was prepared in the same manner as in Example 1 except that it was heat treated at 135 ° C. for 2 days. The transmission loss of the obtained plastic optical fiber is 600 dB / km.
(660 nm: LED). The endothermic peak of the obtained plastic optical fiber by DSC is 147 ° C.
The endothermic amount was 1.2 mJ / mg. When this plastic optical fiber was heated at 135 ° C for one month, the transmission loss was 1200 dB / km (660 nm: L
ED). When the obtained plastic optical fiber was heat-treated at 135 ° C. for 10 days, the shrinkage rate of the fiber was 3.1%.

Comparative Example 3 AD-9000TG (manufactured by Teijin Kasei Co., Ltd.) (glass transition temperature: 142 ° C.) was added as a core layer to the resin introducing passage of the plastic optical fiber spinning apparatus, and spinning was performed at a head temperature of 245 ° C. A die was installed in the middle of spinning, a thermosetting silicone resin (X-38-091 HAB: manufactured by Shin-Etsu Chemical Co., Ltd.) was added to the die to form a clad layer, and then the die was further cured in a furnace below the die. Next, this was heat-treated at 120 ° C. for 3 hours to obtain a plastic optical fiber. The obtained plastic optical fiber had a core diameter of 0.96 mm and an outer diameter of 1.02 mm. Also, the transmission loss is 400 dB.
/ Km (660 nm: LED). As a result of the differential thermal analysis by DSC of the obtained plastic optical fiber, no endothermic peak was observed and an endothermic transition of glass transition temperature was observed at 142 ° C. When this plastic optical fiber was heated at 135 ° C. for one month, the transmission loss was 1300 dB / km (660 nm: LED).
When the obtained plastic optical fiber was heat-treated at 135 ° C. for 10 days, the shrinkage rate of the fiber was 5.3%.

Example 2 48.5 in a reaction vessel equipped with a stirrer, thermometer, reflux condenser.
A 94% aqueous sodium hydroxide solution and 8251 parts of ion-exchanged water were added, and nitrogen gas was bubbled for about 30 minutes to deoxygenate. To this, 2.4 parts of hydrosulfide was added to give 99.99% pure bisphenol AF174.
After dissolving 0.5 parts, 6170 parts of methylene chloride was added, and 600 parts of phosgene was blown thereinto with stirring at 14 to 16 ° C. for about 60 minutes. Then, 42.7 parts of p-tert-butylphenol and 322.6 parts of a 48.5% sodium hydroxide aqueous solution were added, and the mixture was stirred to emulsify, then 1.0 part of triethylamine was added, and the mixture was stirred at 30 ° C. for about 2 hours. The reaction was completed. After the reaction was completed, the product was diluted with methylene chloride, washed with water, acidified with hydrochloric acid and further washed with water. When the conductivity of the aqueous phase became almost the same as that of ion-exchanged water, the methylene chloride was evaporated to remove the polymer. Obtained. The polymer had a specific viscosity of 0.175 and a glass transition temperature of 157 ° C. The above-mentioned polycarbonate resin was added as a core layer to the resin introduction path of the plastic optical fiber spinning apparatus, and spinning was performed at a head temperature of 235 ° C. A die is installed in the middle of spinning, and a thermosetting silicone resin (X-38-
091HAB: manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and further cured in a furnace below the die. Next, this was heat-treated at 140 ° C. for 2 days to obtain a target plastic optical fiber. The obtained plastic optical fiber had a core diameter of 0.96 mm and an outer diameter of 1.02 mm. The transmission loss is 800 dB /
It was km (660 nm: LED). The results of differential thermal analysis by DSC of the obtained plastic optical fiber are shown in FIG. 3. The endothermic peak appeared at 164 ° C. and the endothermic amount was 3.6 mJ / mg. When this plastic optical fiber was heated at 150 ° C. for one month, the transmission loss was 900 dB / km (660 nm: LED).
Further, when the obtained plastic optical fiber was heat-treated at 150 ° C. for 10 days, the shrinkage rate of the fiber was 1.3%.

Comparative Example 4 A plastic optical fiber was prepared in the same manner as in Example 2 except that heat treatment was not performed at 140 ° C. The transmission loss of the obtained plastic optical fiber is 800 dB /
It was km (660 nm: LED). The results of differential thermal analysis of the obtained plastic optical fiber by DSC are shown in FIG. 4, but no endothermic peak was observed and an endothermic transition of glass transition temperature was observed at 156 ° C. When this plastic optical fiber was heated at 150 ° C for 1 month, the transmission loss was 1400 dB / km (660 nm: LE
D). When the obtained plastic optical fiber was heat-treated at 150 ° C. for 10 days, the shrinkage rate of the fiber was 5.0%.

Comparative Example 5 A plastic optical fiber was prepared in the same manner as in Example 1 except that it was heat treated at 150 ° C. for 2 days. The transmission loss of the obtained plastic optical fiber is 900 dB / km.
(660 nm: LED). The results of differential thermal analysis by DSC of the obtained plastic optical fiber are shown in FIG. 5. The endothermic peak appeared at 158 ° C. and the endothermic amount was 1.3 mJ / mg. When this plastic optical fiber was heated at 150 ° C. for one month, the transmission loss was 1300 dB / km (660 nm: LED).
When the obtained plastic optical fiber was heat-treated at 135 ° C. for 10 days, the shrinkage rate of the fiber was 4.5%.

Example 3 3280 parts of ion-exchanged water and 372 parts of 48.5% aqueous sodium hydroxide solution were placed in a reaction vessel equipped with a stirrer, a thermometer, and a reflux condenser, and degassing was carried out by bubbling nitrogen gas for about 50 minutes. did. To this was added 0.99 parts of hydrosulfide, and 99.98% pure bisphenol AF544.
3 parts and 99.98% pure bisphenol AP52.
After dissolving 2 parts, 2150 parts of methylene chloride was added, and 210 parts of phosgene was blown thereinto under stirring at 14 to 16 ° C. over about 60 minutes. Then, 13.3 parts of p-tert-butylphenol and 48.5% sodium hydroxide aqueous solution 7
After 0.0 part was added and the mixture was stirred to emulsify, 0.28 part of triethylamine was added and stirred at 30 ° C. for about 2 hours to complete the reaction. After completion of the reaction, the product was diluted with methylene chloride, washed with water, acidified with hydrochloric acid and further washed with water, and when the conductivity of the aqueous phase was almost the same as that of ion-exchanged water, the methylene chloride was evaporated to perform copolymerization. A polymer was obtained. The specific viscosity of this copolymer was 0.210, and the glass transition temperature was 160 ° C. The above polycarbonate copolymer from which dust was removed through a 0.1 μm filter as a core layer was added to the resin introduction passage, and spinning was performed at a head temperature of 240 ° C. A die was installed in the middle of spinning, and a thermosetting silicone resin (X-38-091 HAB: manufactured by Shin-Etsu Chemical Co., Ltd.) was added to the die to form a clad layer, which was further cured in a furnace below the die. This was heat-treated at 140 ° C. for 3 days to obtain a desired plastic optical fiber. The obtained plastic optical fiber had a core diameter of 0.96 mm and an outer diameter of 1.02 mm. The transmission loss is 830 dB / k.
m (660 nm: LED). When this plastic optical fiber was heated at 150 ° C. for one month, the transmission loss was 930 dB / km (660 nm: LED). As a result of the differential thermal analysis by DSC of the obtained plastic optical fiber, an endothermic peak appeared at 168 ° C. and an endothermic amount was 2.8 mJ / mg. When the obtained plastic optical fiber was heat-treated at 150 ° C. for 10 days, the shrinkage rate of the fiber was 0.5%.

Example 4 249 parts of ion-exchanged water and 16.4 parts of 48.5% aqueous sodium hydroxide solution were placed in a reaction vessel equipped with a stirrer, a thermometer and a reflux condenser, and bubbled with nitrogen gas for about 30 minutes. Deoxygenated. To this was added 0.05 part of hydrosulfide, and 99.98% pure bisphenol AF27.
After dissolving 1 part and 3.14 parts of 9,9-bis (4-hydroxyphenyl) fluorene having a purity of 99.8%, 267 parts of methylene chloride was added, and 10.4 parts of phosgene was added under stirring at 14 to 16 ° C. It took about 60 minutes to blow. Then p
-Tert-butylphenol 0.67 parts and 48.5
% Aqueous sodium hydroxide solution (5.6 parts), and the mixture is stirred to emulsify and then triethylamine (0.02 parts) is added.
The reaction was completed by stirring at C for about 2 hours. After completion of the reaction, the product was diluted with methylene chloride, washed with water, acidified with hydrochloric acid and further washed with water, and when the conductivity of the aqueous phase was almost the same as that of ion-exchanged water, the methylene chloride was evaporated to perform copolymerization. A polymer was obtained. The specific viscosity of this copolymer is 0.21.
1, and the glass transition temperature was 168 ° C. The above polycarbonate copolymer from which dust was removed through a 0.1 μm filter as a core layer was added to the resin introduction path, and spinning was performed at a head temperature of 245 ° C. A die is installed in the middle of spinning and the thermosetting silicone resin (X
-38-040 HAB: manufactured by Shin-Etsu Chemical Co., Ltd.) was added to form a clad layer, and the clad layer was further cured in a furnace below the die.
This was heat-treated at 145 ° C. for 3 days to obtain a desired plastic optical fiber. The obtained plastic optical fiber had a core diameter of 0.96 mm and an outer diameter of 1.02 mm. Transmission loss is 900 dB / km (660 nm: LED)
Met. DS of the obtained plastic optical fiber
As a result of the differential thermal analysis by C, an endothermic peak appeared at 178 ° C. and an endothermic amount was 3.4 mJ / mg. When this plastic optical fiber was heated at 150 ° C for one month, the transmission loss was 1050 dB / km (660 nm: LE).
D). When the obtained plastic optical fiber was heat-treated at 155 ° C. for 10 days, the shrinkage rate of the fiber was 0.3%.

Comparative Example 6 A plastic optical fiber was prepared in the same manner as in Example 3 except that the heat treatment was not performed at 140 ° C. for 3 days. As a result of differential thermal analysis by DSC of the obtained plastic optical fiber, no endothermic peak was observed. The transmission loss of the obtained plastic optical fiber is 830 dB / km (66
0 nm: LED). When this plastic optical fiber was heat-treated at 150 ° C. for 10 days, the shrinkage rate of the fiber was 3.0%.

Comparative Example 7 A plastic optical fiber was prepared in the same manner as in Example 4 except that the heat treatment was not performed at 145 ° C. for 3 days. As a result of differential thermal analysis by DSC of the obtained plastic optical fiber, no endothermic peak was observed. The transmission loss of the obtained plastic optical fiber is 900 dB / km (66
0 nm: LED). When this plastic optical fiber was heat-treated at 155 ° C. for 10 days, the shrinkage rate of the fiber was 2.5%.

[Brief description of drawings]

FIG. 1 is a DSC chart of a core layer of a plastic optical fiber obtained in Example 1.

2 is a DSC chart of the core layer of the plastic optical fiber obtained in Comparative Example 1. FIG.

3 is a DSC chart of the core layer of the plastic optical fiber obtained in Example 2. FIG.

FIG. 4 is a DSC chart of a core layer of a plastic optical fiber obtained in Comparative Example 4.

5 is a DSC chart of the core layer of the plastic optical fiber obtained in Comparative Example 5. FIG.

Claims (4)

[Claims] 1. A plastic optical transmission body having a core portion made of polycarbonate, the endothermic peak of which is 100 ° C. or more and 200 ° C. or less when the polycarbonate of the core portion is subjected to a differential thermal analysis at a heating rate of 10 ° C./min. A plastic optical transmission body, which is a polycarbonate existing in a temperature range and having an endothermic amount of 1.5 mJ / mg or more. 2. A plastic optical fiber having a core portion made of polycarbonate, the endothermic peak of which is 100 ° C. or more and 200 ° C. or less when the core polycarbonate is subjected to a differential thermal analysis at a temperature rising rate of 10 ° C./min. A plastic optical fiber, which is a polycarbonate existing in the range and having an endothermic amount of 1.5 mJ / mg or more. 3. When manufacturing a plastic optical transmission body whose core part is made of polycarbonate, the core part is heat-treated at a temperature 10 ° C. or more lower than the glass transition temperature of the polycarbonate forming the core part for at least 8 hours. A method for manufacturing a plastic optical transmission body, comprising: 4. When manufacturing a plastic optical fiber whose core part is made of polycarbonate, the core part is heat-treated at a temperature 10 ° C. or more lower than the glass transition temperature of the polycarbonate forming the core part for at least 8 hours. A method for producing a plastic optical fiber characterized by the above.