Plastic optical fiber

Abstract

To provide a POF having a coating layer capable of preventing loss deterioration while having excellent thermostability.SOLUTION: A plastic optical fiber 10 includes a core 11, a cladding 12 disposed on a circumference of the core 11, and a coating layer 13 disposed on a circumference of the cladding 12. The coating layer 13 is formed with a resin composition. The resin composition substantially includes no mold-releasing agent but includes a polycarbonate resin having a constitutional unit expressed by a formula (1) below. In the resin composition, glass-transition temperature is 130°C to 150°C, inclusive, and a water absorption percentage is 0.22% or less after being exposed for 24 hours under an environment at 23°C and relative humidity 50%.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to plastic optical fibers.

Background Art

[0002] An optical fiber includes a core as a portion for transmitting light, and a region called a cladding provided on the outer periphery of the core for confining the light in the core.

[0003] Optical fibers include plastic optical fibers (hereinafter referred to as "POF") in which the core is formed of a resin material, and glass optical fibers (hereinafter referred to as "GOF") in which the core is formed of a glass material. POF is more flexible than GOF and is excellent in bending resistance (i.e., flexibility) and processability compared to GOF. Further, POF is lighter than GOF. Due to these advantages of POF, its application to in-vehicle use etc. is expected.

[0004] In POF, the core is formed of a resin material having a high refractive index. The cladding is formed of a resin material having a refractive index lower than that of the resin material of the core in order to keep the light in the core. Further, POF usually has a configuration in which a coating layer is provided on the outer periphery of the cladding for reinforcement. For example, Patent Document 1 discloses a POF having a protective coating layer for improving mechanical strength.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Members mounted on automobiles are exposed to harsh environments or high temperatures due to the heat generated by the engine, so high heat resistance is required. For example, in POF, characteristics that can maintain low loss (i.e., high-speed communication) even when exposed to high temperatures exceeding 105°C and are less likely to deteriorate in loss are desired.

[0007] To improve the heat resistance of POF, it has been proposed to use a resin material with excellent heat resistance for the coating layer of POF. For example, Patent Document 1 describes forming a protective coating layer using a material having a high glass transition temperature.

[0008] However, when the material of the coating layer is selected only from the perspective of heat resistance, it does not conform to the spinning process when manufacturing POF, foreign substances are generated in the coating layer, and these foreign substances become factors for loss deterioration, and may instead deteriorate the loss.

[0009] An object of the present disclosure is to provide a POF having a coating layer with excellent heat resistance and capable of suppressing loss deterioration.

Means for Solving the Problems

[0010] The POF of the present disclosure has a core, a cladding disposed on the outer periphery of the core, a coating layer disposed on the outer periphery of the cladding, and is provided with the coating layer is formed of a resin composition, the resin composition substantially does not contain a release agent, contains a polycarbonate resin containing a structural unit represented by the following formula (1), has a glass transition temperature of 130°C or higher and 150°C or lower, and the water absorption rate when exposed to an environment of 23°C and 50% relative humidity for 24 hours is 0.22% or less.

Chemical formula

[0011] According to the present disclosure, it is possible to provide a POF provided with a coating layer having excellent heat resistance and capable of suppressing deterioration of loss.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0013] The POF according to the embodiment of the present disclosure will be described.

[0014] FIG. 1 is a schematic diagram showing an example of a cross-sectional structure of a POF according to the first embodiment of the present disclosure.

[0015] The POF 10 according to the present embodiment includes a core 11, a clad 12 disposed on the outer periphery of the core 11, and a coating layer 13 disposed on the outer periphery of the clad 12.

[0016] The coating layer 13 is formed of a resin composition. The resin composition substantially does not contain a release agent (Configuration (a)), includes a polycarbonate resin containing a structural unit represented by the following formula (1) (Configuration (b)), has a glass transition temperature of 130°C or higher and 150°C or lower (Configuration (c)), and has a water absorption rate of 0.22% or less when exposed to an environment of 23°C and a relative humidity of 50% for 24 hours (Configuration (d)). [Chemical formula]

[0017] Due to the above configuration, the POF10 of the present embodiment can have an excellent heat resistance and be provided with a coating layer capable of suppressing the deterioration of loss.

[0018] Since the resin composition forming the coating layer 13 has the above Configuration (a), it is possible to suppress the occurrence of defects that cause deterioration of loss in the coating layer by the spinning process (for example, the occurrence of foreign matters). For example, when manufacturing the POF10 using the melt spinning method, the resin composition for forming the POF10 is continuously heated at a high temperature (for example, 230°C or higher) for a long time of about several hours. When heated continuously at a high temperature for such a long time, the release agent contained in the resin composition deteriorates, and as a result, foreign matters are likely to occur. If such foreign matters are contained in the coating layer 13, the loss of the POF10 deteriorates. In addition, such foreign matters also cause linear fluctuations in the POF10. In the POF10 of the present embodiment, since the resin composition forming the coating layer 13 substantially does not contain a release agent, the occurrence of defects that cause deterioration of loss by the spinning process is suppressed. Thereby, the deterioration of the loss of the POF10 is suppressed.

[0019] Here, "the resin composition for forming the coating layer 13 substantially does not contain a release agent" means that the content ratio of the release agent in the resin composition for forming the coating layer 13 is 0.01% by mass or less, preferably 0.005% by mass or less, more preferably 0.002% by mass or less, still more preferably 0.001% by mass or less, and particularly preferably 0.0009% by mass or less. It is particularly preferable that the resin composition for forming the coating layer 13 does not contain a release agent.

[0020] Since the resin composition for forming the coating layer 13 has the above configurations (b) and (c), the heat resistance of the POF 10 can be improved, and it can have a viscosity suitable for the spinning process, so it is less likely to cause defects in the coating layer 13 formed by the spinning process. Therefore, according to the above configurations (b) and (c), the heat resistance of the POF 10 can be improved and the deterioration of loss can be suppressed. In this specification, the glass transition temperature of the resin composition for forming the coating layer 13 is the midpoint glass transition temperature (T mg ) determined in accordance with the provisions of JIS K7121:1987.

[0021] Since the resin composition for forming the coating layer 13 has the above configuration (d), peeling of the coating layer 13 due to moisture absorption is suppressed. Thereby, the deterioration of loss of the POF 10 is suppressed. The water absorption rate of the above configuration (d) was determined as per ISO 62:1999 (Plastics - Determination of water absorption).

[0022] The above release agent is, for example, at least one selected from the group consisting of fatty acids, fatty acid ester compounds, modified products of fatty acid ester compounds, polyglycerin fatty acid esters, and sorbitan fatty acid esters. That is, the resin composition for forming the coating layer 13 substantially does not contain, for example, fatty acids, fatty acid ester compounds, modified products of fatty acid ester compounds, polyglycerin fatty acid esters, and sorbitan fatty acid esters.

[0023] Fatty acid ester compounds and modified products of fatty acid ester compounds are, for example, glycerin fatty acid esters and modified products of glycerin fatty acid esters. For example, the release agent is a compound represented by the following formula (2) and a compound represented by the following formula (3). [Chemical formula] [Chemical formula]

[0024] However, in the above formulas (2) and (3), R 1 , R 2 , R 3 , and R 4 are each independently a linear or branched aliphatic carboxylic acid residue having 5 to 30 carbon atoms.

[0025] Also, the fatty acid is a compound represented by the following formula (4). An example of the fatty acid is montanic acid. [Chemical formula]

[0026] However, in the above formula (4), R 5 is a linear or branched aliphatic carboxylic acid residue having 5 to 30 carbon atoms.

[0027] Here, the aliphatic carboxylic acid residue means that -OR (R: R 1 , R 2 , R 3 , R 4 , or R 5 ) is a fatty acid ester group. The carbon-carbon bond in the aliphatic carboxylic acid residue may contain a double bond.

[0028] The release agent is, for example, at least one selected from the group consisting of the compound represented by the above formula (2), the compound represented by the above formula (3), and the compound represented by the above formula (4). The resin composition for forming the coating layer 13 substantially does not contain, for example, the compound represented by the above formula (2), the compound represented by the above formula (3), and the compound represented by the above formula (4).

[0029] It is preferable that the resin composition has a molecular weight reduction rate of 10% or less after being exposed to an environment of 85°C and 85% relative humidity for 1000 hours. Here, the molecular weight reduction rate is the reduction rate of the weight average molecular weight (B) of the resin composition after being exposed to the environment of 85°C and 85% relative humidity for 1000 hours with respect to the weight average molecular weight (A) of the resin composition before being exposed to the environment, and is obtained by the following mathematical formula (1). The weight average molecular weight (A) and the weight average molecular weight (B) of the resin composition are measured by the gel permeation chromatography (GCP) method. For example, as the apparatus, ACQUITY APC (manufacturer: Waters) is used, PLgel Mixed-B (manufacturer: Agilent) is used for the column, the column temperature is 40°C, chloroform is used as the eluent, and RI can be obtained as the detector.

[0030] Molecular weight reduction rate (%) ={(Molecular weight (A) - Molecular weight (B)) / Molecular weight (A)} × 100 ··· (Mathematical formula 1)

[0031] A resin composition with a molecular weight reduction rate of 10% or less is judged to be less likely to have the resin decomposed by hydrolysis reaction or the like even when exposed to a high humidity environment for a long time. Therefore, the coating layer 13 formed of such a resin composition has excellent moisture resistance. Thereby, the POF10 of this embodiment is less likely to have loss deterioration even when exposed to a high humidity environment for a long time, and excellent moisture resistance can be realized. In order to further improve the moisture resistance of the coating layer 13, the molecular weight reduction rate of the resin composition for forming the coating layer 13 is more preferably 5% or less.

[0032] The resin composition used for forming the coating layer 13 is continuously heated at a high temperature for a long time, for example, in a spinning process. Therefore, the resin composition used for forming the coating layer 13 preferably has a molecular weight reduction rate of 15% or less after being exposed to 240 °C for 10 hours. The method for obtaining the molecular weight reduction rate is the same as that for the case of the molecular weight reduction rate after being exposed to an environment of 85 °C and 85% relative humidity for 1000 hours.

[0033] The polycarbonate resin contained in the resin composition for forming the coating layer 13 only needs to have a structural unit represented by the above formula (1), and may be a copolymer containing the structural unit represented by the above formula (1) and other structural units, or may be a homopolymer of only the structural unit represented by the above formula (1).

[0034] In order to improve heat resistance and further facilitate the realization of excellent moisture resistance with a molecular weight reduction rate of 10% or less as described above, the polycarbonate resin is preferably a homopolymer of only the structural unit represented by the above formula (1). That is, the polycarbonate resin is preferably a compound represented by the following formula (5). [Chemical formula] (However, in the above formula (5), n is an arbitrary integer.)

[0035] In addition, when the polycarbonate resin is a compound represented by the above formula (5), the transparency of the coating layer 13 can be improved.

[0036] The molecular weight of the polycarbonate resin is, for example, as follows. · Weight average molecular weight Mw (×10 4 ): 3.9 - 4.3 · Weight average molecular weight (Mw) / number average molecular weight (Mn): 2.5 - 3.0

[0037] In order to improve heat resistance and further facilitate the realization of excellent moisture resistance with a molecular weight reduction rate of 10% or less as described above, the resin composition forming the coating layer 13 preferably contains 90% by mass or more of the above polycarbonate resin, more preferably 95% by mass or more, and still more preferably 99% by mass or more.

[0038] The resin composition forming the coating layer 13 may not substantially contain an antioxidant. In this case, it is possible to further suppress the occurrence of defects (for example, the generation of foreign matters) that cause deterioration of losses in the coating layer during the spinning process. As a result, the deterioration of losses of POF10 can be further suppressed.

[0039] Here, "the resin composition forming the coating layer 13 substantially does not contain an antioxidant" means that the content ratio of the antioxidant in the resin composition forming the coating layer 13 is 0.01% by mass or less, preferably 0.005% by mass or less, and more preferably 0.001% by mass or less. It is still more preferable that the resin composition forming the coating layer 13 does not contain an antioxidant.

[0040] Regarding the resin composition forming the coating layer 13, the melt volume flow rate of the resin composition (hereinafter referred to as "MVR") measured at 300 °C and a load of 1.2 kg in accordance with ISO1133 is 20 cm 3 / 10 min or more and 26 cm 3 / 10 min or less is preferable. Thereby, it is possible to achieve both the stretchability after the discharge of the resin composition and the fluidity of the resin composition in the spinning process, and it is possible to manufacture POF with a stable diameter.

[0041] Hereinafter, each configuration of POF10 of the present embodiment will be described in more detail.

[0042] (Core 11) The core 11 is a region for transmitting light. The core 11 is formed of a resin material having a refractive index higher than that of the cladding 12. With this configuration, the light incident on the core 11 is confined inside the core 11 by the cladding 12 and propagates within the POF 10.

[0043] The core 11 contains a first resin. The core 11 may contain the first resin as a main component. Here, when the core 11 contains the first resin as a main component, it means that the component contained most in terms of mass ratio in the core 11 is the first resin. The core 11 may contain 75% by mass or more of the first resin, 80% by mass or more, or 85% by mass or more.

[0044] In addition to the first resin, the core 11 may further contain an additive. The additive is, for example, a refractive index modifier. That is, the core 11 may be formed of a resin composition containing the first resin and an additive such as a refractive index modifier. As the refractive index modifier, for example, a known refractive index modifier used for the material of the core 11 of the POF 10 can be used. The material of the core 11 may contain other additives other than the refractive index modifier.

[0045] When the POF 10 is, for example, a graded index (GI) type, the core 11 has a refractive index distribution in which the refractive index changes in the radial direction (see the arrow in FIG. 1). Such a refractive index distribution can be formed, for example, by adding a refractive index modifier to the first resin and diffusing (for example, thermally diffusing) the refractive index modifier in the first resin.

[0046] The first resin contained in the core 11 may be any resin having high transparency and is not particularly limited. Examples of the first resin include fluorine-containing resins, acrylic resins such as methyl methacrylate, styrene resins, and carbonate resins.

[0047] The first resin contained in the core 11 may be at least one selected from the group consisting of a perfluorinated resin, a partially fluorinated resin, a partially chlorinated resin, and a partially deuterated resin. Here, the partially fluorinated resin, the partially chlorinated resin, and the partially deuterated resin mean resins in which some of the hydrogen atoms of the C-H bonds are respectively fluorine-substituted, chlorine-substituted, and deuterium-substituted in resins known in the art as core materials for POF. The perfluorinated resin means, here, a resin in which all of the hydrogen atoms of the C-H bonds are fluorine-substituted in resins known in the art as core materials for POF. Examples of resins known in the art as core materials include acrylic resins such as methyl methacrylate as described above, styrene resins, and carbonate resins. A polymer having an aliphatic ring structure such as a polymer having a dioxolane structure may be used.

[0048] It is desirable that the first resin is at least one selected from the group consisting of a perfluorinated resin and a partially fluorinated resin. That is, it is desirable that the first resin is a fluorine-containing resin.

[0049] The first resin of the core 11 is preferably a fluorine-containing resin containing a fluorine-containing polymer. Hereinafter, the fluorine-containing resin contained in the core 11 is referred to as the first fluorine-containing resin, and the fluorine-containing polymer contained in the first fluorine-containing resin is referred to as the first fluorine-containing polymer.

[0050] From the viewpoint of suppressing light absorption due to the stretching energy of the C-H bond, the first fluorine-containing polymer contained in the first fluorine-containing resin preferably contains substantially no hydrogen atoms, and it is particularly preferable that all hydrogen atoms bonded to carbon atoms are substituted with fluorine atoms. That is, the first fluorine-containing polymer preferably contains substantially no hydrogen atoms and is fully fluorinated. In the present specification, that the fluorine-containing polymer contains substantially no hydrogen atoms means that the hydrogen atom content in the fluorine-containing polymer is 1 mol% or less.

[0051] The first fluorine-containing polymer preferably has a fluorine-containing aliphatic ring structure. The fluorine-containing aliphatic ring structure may be included in the main chain of the fluorine-containing polymer or may be included in the side chain of the first fluorine-containing polymer. The first fluorine-containing polymer has, for example, a structural unit (A) represented by the following formula (6).

Chemical formula

[0052] In formula (6), R ff 1 ~R ff 4 each independently represents a fluorine atom, a perfluoroalkyl group having 1 to 7 carbon atoms, or a perfluoroalkyl ether group having 1 to 7 carbon atoms. R ff 1 and R ff 2 may be linked to form a ring. "Perfluoro" means that all hydrogen atoms bonded to carbon atoms are substituted with fluorine atoms. In formula (6), the number of carbon atoms of the perfluoroalkyl group is preferably 1 to 5, more preferably 1 to 3, and even more preferably 1. The perfluoroalkyl group may be linear or branched. Examples of the perfluoroalkyl group include a trifluoromethyl group, a pentafluoroethyl group, and a heptafluoropropyl group.

[0053] In formula (6), the number of carbon atoms of the perfluoroalkyl ether group is preferably 1 to 5, more preferably 1 to 3. The perfluoroalkyl ether group may be linear or branched. Examples of the perfluoroalkyl ether group include a perfluoromethoxymethyl group.

[0054] R ff 1 and R ff 2When they are connected to form a ring, the ring may be a 5-membered ring or a 6-membered ring. Examples of such rings include a perfluorotetrahydrofuran ring, a perfluorocyclopentane ring, and a perfluorocyclohexane ring.

[0055] Specific examples of the structural unit (A) include, for example, structural units represented by the following formulas (A1) to (A8).

Chemical formula

[0056] The structural unit (A) is preferably the structural unit (A2), that is, the structural unit represented by the following formula (7) among the structural units represented by the above formulas (A1) to (A8).

Chemical formula

[0057] The first fluorine-containing polymer may contain one or more kinds of the structural unit (A). In the first fluorine-containing polymer, the content of the structural unit (A) is preferably 20 mol% or more, more preferably 40 mol% or more, based on the total of all the structural units. When the structural unit (A) is contained in an amount of 20 mol% or more, the first fluorine-containing polymer tends to have higher heat resistance. When the structural unit (A) is contained in an amount of 40 mol% or more, the first fluorine-containing polymer tends to have higher transparency and higher mechanical strength in addition to high heat resistance. In the first fluorine-containing polymer, the content of the structural unit (A) is preferably 95 mol% or less, more preferably 70 mol% or less, based on the total of all the structural units.

[0058] The structural unit (A) is derived from, for example, a compound represented by the following formula (8). In formula (8), R ff 1 ~R ff 4is the same as formula (6). The compound represented by formula (8) can be obtained by known production methods, including, for example, the production method disclosed in Japanese Patent Application Laid-Open No. 2007-504125.

Chem.

[0059] Specific examples of the compound represented by the above formula (8) include, for example, compounds represented by the following formulas (M1) to (M8).

Chem.

[0060] The fluorine-containing polymer may further contain other constitutional units in addition to the constitutional unit (A). Examples of the other constitutional units include the following constitutional units (B) to (D).

[0061] The constitutional unit (B) is represented by the following formula (9).

Chem.

[0062] In formula (9), R 1 ~R 3 each independently represents a fluorine atom or a perfluoroalkyl group having 1 to 7 carbon atoms. R 4 represents a perfluoroalkyl group having 1 to 7 carbon atoms. The perfluoroalkyl group may have a ring structure. A part of the fluorine atoms may be substituted with halogen atoms other than fluorine atoms. A part of the fluorine atoms in the perfluoroalkyl group may be substituted with halogen atoms other than fluorine atoms.

[0063] The fluorine-containing polymer may contain one or more kinds of the constitutional unit (B). In the fluorine-containing polymer, the content of the constitutional unit (B) is preferably 5 to 10 mol% based on the total of all constitutional units. The content of the constitutional unit (B) may be 9 mol% or less, or may be 8 mol% or less.

[0064] The structural unit (B) is derived from, for example, a compound represented by the following formula (10). In formula (10), R 1 ~R 4 is the same as in formula (9). The compound represented by formula (10) is a fluorine-containing vinyl ether such as perfluorovinyl ether. [Chemical formula]

[0065] The structural unit (C) is represented by the following formula (11). [Chemical formula]

[0066] In formula (11), R 5 ~R 8 each independently represents a fluorine atom or a perfluoroalkyl group having 1 to 7 carbon atoms. The perfluoroalkyl group may have a ring structure. A part of the fluorine atoms may be substituted with halogen atoms other than fluorine atoms. A part of the fluorine atoms in the perfluoroalkyl group may be substituted with halogen atoms other than fluorine atoms.

[0067] The fluorine-containing polymer may contain one or more structural units (C). In the fluorine-containing polymer, the content of the structural unit (C) is preferably 5 to 10 mol% based on the total of all structural units. The content of the structural unit (C) may be 9 mol% or less, or may be 8 mol% or less.

[0068] The structural unit (C) is derived from, for example, a compound represented by the following formula (12). In formula (12), R 5 ~R 8 is the same as in formula (11). The compound represented by formula (12) is a fluorine-containing olefin such as tetrafluoroethylene and chlorotrifluoroethylene. [Chemical formula]

[0069] The structural unit (D) is represented by the following formula (13). [Chemical formula]

[0070] In formula (13), Z represents an oxygen atom, a single bond, or -OC(R 19 R 20 )O-, and R 9 ~R 20 each independently represents a fluorine atom, a perfluoroalkyl group having 1 to 5 carbon atoms, or a perfluoroalkoxy group having 1 to 5 carbon atoms. A part of the fluorine atoms may be substituted with halogen atoms other than fluorine atoms. A part of the fluorine atoms in the perfluoroalkyl group may be substituted with halogen atoms other than fluorine atoms. A part of the fluorine atoms in the perfluoroalkoxy group may be substituted with halogen atoms other than fluorine atoms. s and t are each independently an integer from 0 to 5 and s + t is an integer from 1 to 6 (however, when Z is -OC(R 19 R 20 )O-, s + t may be 0).

[0071] The structural unit (D) is preferably represented by the following formula (14). The structural unit represented by the following formula (14) is the case where Z is an oxygen atom, s is 0, and t is 2 in the above formula (13). [Chemical formula]

[0072] In formula (14), R 141 , R 142 , R 151 , and R 152Each independently represents a fluorine atom, a perfluoroalkyl group having 1 to 5 carbon atoms, or a perfluoroalkoxy group having 1 to 5 carbon atoms. A part of the fluorine atoms may be substituted with halogen atoms other than fluorine atoms. A part of the fluorine atoms in the perfluoroalkyl group may be substituted with halogen atoms other than fluorine atoms. A part of the fluorine atoms in the perfluoroalkoxy group may be substituted with halogen atoms other than fluorine atoms.

[0073] The fluorine-containing polymer may contain one or more kinds of structural units (D). In the fluorine-containing polymer, the content of the structural unit (D) is preferably 30 to 67 mol% based on the total of all the structural units. The content of the structural unit (D) may be, for example, 35 mol% or more and 60 mol% or less, or may be 55 mol% or less.

[0074] The structural unit (D) is derived from, for example, a compound represented by the following formula (15). In formula (15), Z, R 9 ~R 18 , s and t are the same as those in formula (13). The compound represented by formula (11) is a fluorine-containing compound having two or more polymerizable double bonds and capable of undergoing cyclopolymerization.

Chemical formula

[0075] The structural unit (D) is preferably derived from a compound represented by the following formula (16). In formula (16), R 141 , R 142 , R 151 , and R 152 are the same as those in formula (14).

Chemical formula

[0076] Specific examples of the compound represented by formula (15) or formula (16) include the following compounds. CF2=CFOCF2CF=CF2 CF2=CFOCF(CF3)CF=CF2 CF2=CFOCF2CF2CF=CF2 CF2=CFOCF2CF(CF3)CF=CF2 CF2=CFOCF(CF3)CF2CF=CF2 CF2=CFOCFClCF2CF=CF2 CF2=CFOCCl2CF2CF=CF2 CF2=CFOCF2OCF=CF2 CF2=CFOC(CF3)2OCF=CF2 CF2=CFOCF2CF(OCF3)CF=CF2 CF2=CFCF2CF=CF2 CF2=CFCF2CF2CF=CF2 CF2=CFCF2OCF2CF=CF2 CF2=CFOCF2CFClCF=CF2 CF2=CFOCF2CF2CCl=CF2 CF2=CFOCF2CF2CF=CFCl CF2=CFOCF2CF(CF3)CCl=CF2 CF2=CFOCF2OCF=CF2 CF2=CFOCCl2OCF=CF2 CF2=CClOCF2OCCl=CF2

[0077] The first fluorine-containing polymer may further contain other constitutional units in addition to the constitutional units (A) to (D), but preferably substantially does not contain other constitutional units than the constitutional units (A) to (D). Note that the fact that the fluorine-containing polymer substantially does not contain other constitutional units than the constitutional units (A) to (D) means that the total of the constitutional units (A) to (D) is 95 mol% or more, preferably 98 mol% or more, based on the total of all constitutional units in the fluorine-containing polymer.

[0078] The polymerization method of the first fluorine-containing polymer is not particularly limited, and for example, general polymerization methods such as radical polymerization can be used. The polymerization initiator for polymerizing the fluorine-containing polymer may be a fully fluorinated compound.

[0079] The first fluorine-containing polymer constitutes a first fluorine-containing resin used as the first resin. The first glass transition temperature Tg1 of the first resin is not particularly limited, and is, for example, above 105 °C and below 140 °C, and may be 120 °C or higher. In this specification, Tg means the midpoint glass transition temperature (T mg ) determined in accordance with the provisions of JIS K7121:1987.

[0080] (Cladding 12) In the POF10 of this embodiment, the cladding 12 contains, for example, a second resin. The cladding 12 may contain the second resin as a main component. Here, that the cladding 12 contains the second resin as a main component means that in the cladding 12, the component contained in the largest amount by mass is the second resin. The cladding 12 may contain 80% by mass or more of the second resin, 90% by mass or more, or 95% by mass or more. The cladding 12 may be composed only of the second resin. The cladding 12 may further contain additives in addition to the second resin.

[0081] The second resin contained in the cladding 12 may be any resin having high transparency and is not particularly limited. Examples of the second resin are the same as those exemplified as resins that can be used as the first resin. Similar to the first resin, a fluorine-containing resin is preferably used as the second resin.

[0082] The second resin of the cladding 12 is preferably a fluorine-containing resin containing a fluorine-containing polymer. Hereinafter, the fluorine-containing resin contained in the cladding 12 is referred to as a second fluorine-containing resin, and the fluorine-containing polymer contained in the second fluorine-containing resin is referred to as a second fluorine-containing polymer.

[0083] As the second fluorine-containing resin, those exemplified as fluorine-containing resins that can be used as the first fluorine-containing resin can be used.

[0084] As the second fluorine-containing resin, a fluorine-containing polymer containing a structural unit (E) represented by the following formula (17) and having an amorphous structure, and a fluorine-containing plasticizer may be used.

Chemical formula

[0085] The fluorine-containing polymer containing the structural unit (E) may further contain a structural unit (F) represented by the following formula (18).

Chemical formula

[0086] When the second fluorine-containing polymer is the above copolymer, the ratio of the structural unit (E) to the structural unit (F) is arbitrary and not particularly limited.

[0087] The second fluorine-containing polymer is preferably at least one selected from the group consisting of, for example, the fluorine-containing polymers A and B shown below.

[0088] The fluorine-containing polymer A contains a structural unit (G) represented by the following formula (19) and a structural unit (H) represented by the following formula (20). In the following formula (19), R 23 , R 24 , R 31 , and R 32 are the same as those in the above formula (17).

[0089]

Chemical formula

Chemical formula

[0090] The fluorine-containing polymer B contains a structural unit (I) represented by the following formula (21). In the following formula (21), R 21 to R 24 , R 27 to R 30 , R 31 , and R 32 are the same as those in the above formula (17).

Chemical formula

[0091] The above-mentioned fluorine-containing polymer A and fluorine-containing polymer B have very high transparency and can have a very low refractive index as compared with the general refractive index of the first fluorine-containing resin used for the material of the core 11. Therefore, the second fluorine-containing resin containing at least one selected from the group consisting of the fluorine-containing polymer A and the fluorine-containing polymer B as the second fluorine-containing polymer can further reduce the refractive index while maintaining the high transparency of the cladding 12. As a result, the difference between the refractive index of the core 11 and the refractive index of the cladding 12 can be further increased, so that the light confinement effect of the cladding 12 into the core 11 is further improved, and it becomes easier to achieve the low transmission loss of the POF 10.

[0092] The second fluorine-containing polymer preferably contains a structural unit (J) represented by the following formula (22). [Chemical formula] (In formula (22), m and n are arbitrary integers)

[0093] The fluorine-containing plasticizer is preferably a fluorine-containing polyether, and more preferably a perfluoropolyether.

[0094] Specific examples of the perfluoropolyether include organic compounds represented by the following formula (23) or (24). In the following formulas (23) and (24), p1, q1, p2, and q2 are each an arbitrary integer. CF3-[(O(CF3)CFCF2) p1 -(OCF2) q1 OCF3(23) CF3-[(OCF2CF2) p2 -(OCF2) q2 OCF3(24)

[0095] The second fluorine-containing polymer constitutes the second fluorine-containing resin used as the second resin. The second glass transition temperature Tg2 of the second resin is not particularly limited, and is, for example, more than 105 °C and 170 °C or less, and may be 125 °C or more.

[0096] (Coating layer 13) The resin composition for forming the coating layer 13 is as described above.

[0097] The thickness of the coating layer 13 is preferably, for example, 50 μm or more and 250 μm or less. When the thickness of the coating layer 13 is 50 μm or more, the core 11 and the clad 12 can be sufficiently protected by the coating layer 13, so that a highly reliable POF 10 can be obtained. Further, when the thickness of the coating layer 13 is 250 μm or less, a highly flexible POF 10 can be obtained.

[0098] (Modified example of POF) FIG. 2 shows a modified example of the POF of the present embodiment. The POF 20 shown in FIG. 2 has a configuration in which a coloring layer 21 is further provided on the outer periphery of the coating layer 13 so as to cover the coating layer 13 with respect to the POF 10. Such a coloring layer 21 is provided, for example, for the purpose of improving the discriminability of the POF. The thickness of the coloring layer 21 is, for example, 5 μm or more and 20 μm or less. By setting the thickness within such a range, the surface of the POF can be appropriately colored by the coloring layer 21.

[0099] The above-described resin composition for forming the coating layer 13 in the POF 20 of the present embodiment is excellent in adhesion to the material (coloring agent) used for the coloring layer 21. Therefore, even in the configuration in which the coloring layer 21 is provided, delamination between the layers of each layer constituting the POF 20 is less likely to occur, and the POF 20 can have high reliability.

[0100] (Manufacturing method of POF) The POF of the present embodiment is manufactured, for example, by using a melt spinning method. That is, an example of the manufacturing method of the POF of the present embodiment is melting the core material and extruding it into a fiber shape to produce a fiber-shaped molded body made of the core material, Melting the cladding material and extruding it to coat the surface of the molded body to produce a first laminate in which the core material and the cladding material are concentrically laminated, Melting the resin composition for forming the coating layer and extruding it to coat the surface of the first laminate to produce a second laminate in which the core material, the cladding material, and the resin composition are concentrically laminated, including.

[0101] The core material includes, for example, a first resin. The cladding material includes, for example, a second resin. The resin composition for forming the coating layer is a resin composition for forming the coating layer, as described above.

[0102] When producing a fiber-shaped molded body made of a core material, first, a first core material containing a refractive index adjuster is extruded to form a core inner layer portion, and then a second core material is extruded to coat the outer periphery of the core inner layer portion 2 formed by the first core material 1a. In this case, by diffusing the refractive index adjuster contained in the first core material toward the core outer periphery portion formed by the second core material, a core 11 having a refractive index distribution can be formed.

[0103] FIG. 3 is a schematic cross-sectional view showing an example of a manufacturing apparatus that can be used for manufacturing the POF 10 shown in FIG. 1.

[0104] The apparatus 1000 shown in FIG. 3 includes a first extrusion device 101a for extruding a first core material, a second extrusion device 101b for extruding a second core material, a third extrusion device 101c for extruding a cladding material, and a fourth extrusion device 101d for forming a coating layer.

[0105] The first extrusion device 101a includes a first accommodating portion 102a that houses the first core material 1a, and a first extrusion portion 103a that extrudes the first core material 1a housed in the first accommodating portion 102a from the first accommodating portion 102a. The first extrusion device 101a is further provided with a heating portion (not shown) so that the first core material 1a can be melted in the first accommodating portion 102a and can remain in a molten state until the molten first core material 1a is formed. The rod-shaped first core material (preform) 1a is inserted into the first accommodating portion 102a through the opening above the first accommodating portion 102a and is melted by being heated in the first accommodating portion 102a.

[0106] In the first extrusion device 101a, the first core material 1a is extruded outward through the first extrusion portion 103a by gas extrusion so as to form the core inner layer portion 2 from the first accommodating portion 102a. The first core material 1a extruded through the first extrusion portion 103a so as to form the core inner layer portion 2 then moves vertically downward and is supplied to the first chamber 110.

[0107] The second extrusion device 101b includes a second accommodation part 102b that accommodates the second core material 1b, and a second extrusion part 103b that extrudes the second core material 1b accommodated in the second accommodation part 102b from the second accommodation part 102b. The second extrusion device 101b extrudes the molten second core material so as to cover the outer periphery of the core inner layer part 2 formed of the first core material 1a extruded from the first extrusion device 101a. Specifically, the second core material extruded from the second extrusion device 101b is supplied to the first chamber 110. In the first chamber 110, by covering the core inner layer part 2 formed of the first core material 1a with the second core material, a core outer periphery part 3 that covers the outer periphery of the core inner layer part 2 can be formed. The laminate 4 formed by the core inner layer part 2 and the core outer periphery part 3 that covers the outer periphery of the core inner layer part 2 moves from the first chamber 110 to a diffusion tube 120 disposed vertically below the first chamber 110. A heater (not shown) for heating this laminate is disposed in the diffusion tube 120. The diffusion tube 120 diffuses a refractive index adjusting agent or the like contained in the core inner layer part 2 of the laminate 4 passing through the inside of the diffusion tube 120 toward the core outer periphery part 3. That is, finally, the core is formed by the core inner layer part 2 and the core outer periphery part 3.

[0108] The third extrusion device 101c includes a third accommodation part 102c that accommodates the cladding material 1c, and a third extrusion part 103c that extrudes the cladding material 1c accommodated in the third accommodation part 102c from the third accommodation part 102c. The third extrusion device 101c extrudes the molten cladding material 1c so as to cover the outer periphery of the laminate 4 that has passed through the diffusion tube 120. Specifically, the cladding material 1c extruded from the third extrusion device 101c is supplied to the second chamber 130. In the second chamber 130, by covering the laminate 4 (that is, the core) with the cladding material 1c, a cladding 5 that covers the outer periphery of the core can be formed. Hereinafter, the laminate 4 is referred to as the core 4. The laminate formed by the core 4 and the cladding 5 moves from the second chamber 130 to a third chamber 140 disposed vertically below the second chamber 130.

[0109] The fourth extrusion device 101d includes a fourth accommodation part 102d that accommodates a resin composition 1d for forming a coating layer, a screw 104 disposed within the fourth accommodation part 102d, and a hopper 105 connected to the fourth accommodation part 102d. In the fourth extrusion device 101d, for example, the pellet-shaped resin composition 1d is supplied to the fourth accommodation part 102d through the hopper 105. The resin composition 1d supplied to the fourth accommodation part 102d is kneaded by the screw 104 while being heated, thereby softening and becoming flowable. The softened resin composition 1d is extruded from the fourth accommodation part 102d by the screw 104.

[0110] The resin composition 1d extruded from the fourth extrusion device 101d is supplied to the third chamber 140. In the third chamber 140, by coating the surface of the first laminate formed of the core 4 and the clad 5 with the resin composition 1d, a coating layer 6 that covers the outer periphery of the clad 5 is formed.

[0111] The second laminate 7 in which the core 4, the clad 5, and the coating layer 6 are laminated concentrically flows into the internal flow path from the third chamber 140 through the inlet of the nozzle 150. The second laminate 7 passes through the internal flow path and is reduced in diameter, and is discharged in a fiber shape from the discharge port of the nozzle 150.

[0112] The second laminate 7 discharged in a fiber shape from the discharge port of the nozzle 150 flows into the internal space 161 of the cooling pipe 160, is cooled while passing through the internal space 161, and is discharged from the opening to the outside of the cooling pipe 160. The second laminate 7 discharged from the cooling pipe 160 passes between the two rolls 171 and 172 of the nip roll 170, and further passes through the guide rolls 173 to 175, and is wound around the winding roll 176 as the POF 10. A displacement meter 180 for measuring the outer diameter of the POF 10 may be further provided in the vicinity of the winding roll 176, for example, between the guide roll 175 and the winding roll 176.

Example

[0113] (Example 1) [Production of the First Fluorine-Containing Resin] As the first fluorine-containing resin, a polymer of perfluoro-4-methyl-2-methylene-1,3-dioxolane (PFMMD) was prepared. Perfluoro-4-methyl-2-methylene-1,3-dioxolane was synthesized by first synthesizing 2-carboxymethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane, fluorinating this, and separating the resulting carboxylate by decarboxylation. For the polymerization of perfluoro-4-methyl-2-methylene-1,3-dioxolane, perfluorobenzoyl peroxide was used as a polymerization initiator.

[0114] The details of the synthesis of 2-carboxymethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane, the fluorination of 2-carboxymethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane, the synthesis of perfluoro-4-methyl-2-methylene-1,3-dioxolane, and the polymerization of perfluoro-4-methyl-2-methylene-1,3-dioxolane will be described in detail below.

[0115] <Synthesis of 2-carboxymethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane> Prepare a 3L three-necked flask equipped with a water-cooled cooler, a thermometer, a magnetic stirrer, and an isobaric dropping funnel, and charge 139.4 g (1.4 mol in total) of a mixture of 2-chloro-1-propanol and 1-chloro-2-propanol into the flask. Cool the flask to 0 °C, slowly add methyl trifluoropyruvate thereto, and stir for another 2 hours. Then add 100 mL of dimethyl sulfoxide (DMSO) and 194 g of potassium carbonate thereto over 1 hour, and continue stirring for 8 hours to obtain a reaction mixture. Mix the resulting reaction mixture with 1 L of water, separate the aqueous phase, extract this with dichloromethane, mix this dichloromethane solution with the organic reaction mixture phase, and dry the solution with magnesium sulfate. After removing the solvent, 245.5 g of a crude product was obtained. Fractionate this crude product under reduced pressure (12 Torr) to obtain 230.9 g of a purified product of 2-carbomethoxy-2-trifluoromethyl-4-methyl-1,3-dioxolane. The boiling point of the purified product was 77 - 78 °C, and the yield was 77%. The fact that the obtained purified product was 2-carbomethoxy-2-trifluoromethyl-4-methyl-1,3-dioxolane was confirmed by HNMR and 19 FNMR.

[0116] HNMR (ppm): 4.2 - 4.6, 3.8 - 3.6 (CHCH2, multiplet, 3H), 3.85 - 3.88 (COOCH3, multiplet, 3H), 1.36 - 1.43 (CCH3, multiplet, 3H) 19 FNMR (ppm): -81.3 (CF3, s, 3F)

[0117] <Fluorination of 2-carbomethoxy-2-trifluoromethyl-4-methyl-1,3-dioxolane> 4 L of 1,1,2-trichlorotrifluoroethane was injected into a 10 L stirred reaction tank. In the stirred reaction tank, nitrogen was flowed at a flow rate of 1340 cc / min and fluorine was flowed at a flow rate of 580 cc / min to create a nitrogen / fluorine atmosphere. After 5 minutes, 290 g of 2-carbomethoxy-2-trifluoromethyl-4-methyl-1,3-dioxolane previously prepared was dissolved in a 750 mL 1,1,2-trichlorotrifluoroethane solution, and this solution was added to the reaction tank at a rate of 0.5 ml / min. The reaction tank was cooled to 0 °C. After all the dioxolane was added in 24 hours, the fluorine gas flow was stopped. After purging with nitrogen gas, an aqueous potassium hydroxide solution was added until it became weakly alkaline.

[0118] After removing volatile substances under reduced pressure, the surroundings of the reaction tank were cooled, and then dried under reduced pressure at 70 °C for 48 hours to obtain a solid reaction product. The solid reaction product was dissolved in 500 mL of water, excess hydrochloric acid was added, and it was separated into an organic phase and an aqueous phase. The organic phase was separated and distilled under reduced pressure to obtain perfluoro-2,4-dimethyl-1,3-dioxolane-2-carboxylic acid. The boiling point of the main distillate was 103 °C - 106 °C / 100 mmHg. The fluorination yield was 85%.

[0119] <Synthesis of Perfluoro-4-methyl-2-methylene-1,3-dioxolane> The above distillate was neutralized with an aqueous potassium hydroxide solution to obtain potassium perfluoro-2,4-dimethyl-2-carboxylate-1,3-dioxolane. This potassium salt was vacuum dried at 70 °C for 1 day. The salt was decomposed at 250 °C - 280 °C and under a nitrogen or argon atmosphere. It was condensed with a cooling trap cooled to -78 °C to obtain perfluoro-4-methyl-2-methylene-1,3-dioxolane with a yield of 82%. The boiling point of the product was 45 °C / 760 mmHg. 19 The product was identified using 19F NMR and GC-MS.

[0120] 19 19F NMR: -84 ppm (3F, CF3), -129 ppm (2F, =CF2) GC-MS: m / e 244 (Molecular ion), 225, 197, 169, 150, 131, 100, 75, 50.

[0121] <Polymerization of perfluoro-4-methyl-2-methylene-1,3-dioxolane> 100 g of perfluoro-4-methyl-2-methylene-1,3-dioxolane obtained by the above method and 1 g of perfluorobenzoyl peroxide were sealed in a glass tube. This glass tube was purged with argon after removing oxygen in the system by the freeze-degassing method and then heated at 50 °C for several hours. The content became solid, but when it was further heated at 70 °C overnight, a 100 g transparent rod-shaped product was obtained.

[0122] The obtained transparent rod-shaped product was dissolved in Fluorinert FC-75 (manufactured by Sumitomo 3M Limited), and the resulting solution was poured onto a glass plate to obtain a thin film of the polymer. The glass transition temperature of the obtained polymer was 117 °C and it was completely amorphous. The transparent rod-shaped product was dissolved in hexafluorobenzene, and chloroform was added thereto for precipitation to purify the product. The glass transition temperature of the purified polymer was about 131 °C. This polymer was used as the first fluorine-containing resin.

[0123] [Refractive index adjuster] As the refractive index adjuster, chlorotrifluoroethylene oligomer (molecular weight 700 - 850) was used. Specifically, "Daifloyl #10" manufactured by Daikin Industries, Ltd. was distilled, and the component with a molecular weight of 700 - 850 was separated. The separated component with a molecular weight of 700 - 850 was filtered through a filter "DFA1ANDESW44" (manufactured by PALL Corporation) with a pore size of 40 nm to obtain the refractive index adjuster.

[0124] [First core material] The first fluorine-containing resin produced by the above method was dissolved in Bartrel XF-UP (manufactured by Mitsui Chemicals Fluoro Products Co., Ltd.), which is a solvent. The resulting solution was filtered twice through a filter with a pore size of 100 nm, "LPJ-CTA-001-N3" (manufactured by Lokitechno Co., Ltd.). The filtrate was dropped into a Hastelloy container heated to 260°C to evaporate the solvent and dried. The fluorine-containing resin after the filtration treatment obtained by drying and the above refractive index adjuster were melt-mixed at 260°C to prepare a resin composition. The concentration of the refractive index adjuster in the obtained resin composition was 12% by mass. This resin composition was used as the first core material.

[0125] [Second Core Material] The first fluorine-containing resin produced by the above method was filtered in the same manner as the filtration of the fluorine-containing resin in the production of the first core material to obtain a fluorine-containing resin after the filtration treatment. This fluorine-containing resin after the filtration treatment was used as the second core material.

[0126] [Cladding Material] As the cladding material, a second fluorine-containing resin was prepared. "Teflon AF1600" (manufactured by Mitsui Chemicals Fluoro Products Co., Ltd.) as the second fluorine-containing resin and "Fomblin YR" (manufactured by Solvay) as a plasticizer were dissolved in Bartrel XF-UP (manufactured by Mitsui Chemicals Fluoro Products Co., Ltd.), which is a solvent. The mixing ratio of "Teflon AF1600" and "Fomblin YR" was 7:3 by mass ratio, i.e., "Teflon AF1600": "Fomblin YR" = 7:3. The resulting solution was filtered through a filter with a pore size of 300 nm, "LPA-SLF-003-N2" (manufactured by Lokitechno Co., Ltd.). The filtrate was dropped into a Hastelloy container heated to 260°C to evaporate the solvent and dried. The resin composition obtained by drying was used as the cladding material.

[0127] [Resin Composition for Coating Layer Formation] As the resin composition for coating layer formation, a resin composition containing no mold release agent and containing a polycarbonate resin was prepared by removing the mold release agent from Panlite L-1225LM (manufactured by Teijin Limited).

[0128] The resin composition prepared for forming the coating layer had the following physical properties. · Glass transition temperature: 145°C · Water absorption rate when exposed to an environment of 23°C and 50% relative humidity for 24 hours: 0.20% · Molecular weight reduction rate after being exposed to an environment of 85°C and 85% relative humidity for 1000 hours: less than 3% · MVR: 24 cm 3 / 10 min

[0129] [Production of POF] Using the first core material, the second core material, the cladding material, and the resin composition for forming the coating layer prepared by the above method, a POF having the same configuration as POF10 shown in FIG. 1 was produced by the melt spinning method. In this example, the production apparatus shown in FIG. 3 was used for the production of the POF.

[0130] In this example, the inner diameter (diameter) of the diffusion tube 120 was 6.3 mm. The length of the diffusion tube 120 was set so that the diffusion time was 120 min.

[0131] In this example, the melting temperature of the first core material was 250°C, the melting temperature of the second core material was 255°C, the melting temperature of the cladding material was 260°C, and the melting temperature of the resin composition for forming the coating layer was 250°C. Also, the temperature of the diffusion tube 120 was set to 275°C. The core was formed by the first core material and the second core material. The temperature for pulling down the second laminate composed of the core, the cladding, and the coating layer was 240°C.

[0132] The volume ratio of the discharge of each material was melt-extruded at a ratio of 1.6 for the second core material, 0.1 for the cladding material, and 48.6 for the resin composition for forming the coating layer with respect to 1 of the first core material.

[0133] In the first chamber 110 shown in FIG. 3, the temperature of the joining mold used when coating the core inner layer portion formed of the first core material with the second core material was set to 260°C. In the second chamber 130 shown in FIG. 3, the temperature of the joining mold used when coating the core with the cladding material was set to 205°C. In the third chamber 140 shown in FIG. 3, the temperature of the joining mold used when coating the surface of the laminate formed of the core and the cladding with the coating layer material was set to 250°C.

[0134] Regarding the POF produced in Example 1, the core diameter (outer diameter of the core) measured by the method described below was 50 μm, the outer diameter of the cladding was 60 μm, and the outer diameter of the coating layer was 232 μm.

[0135] (Comparative Example 1) As the resin composition for forming the coating layer, Xylex 7200 (manufactured by SABIC, glass transition temperature: 113°C) was used. Except for this point, a POF was produced in the same manner as in Example 1. Regarding Xylex, the molecular weight reduction rate after being exposed to an environment of 85°C and 85% relative humidity for 1000 hours was 60%.

[0136] (Comparative Example 2) As the resin composition for forming the coating layer, Panlite L-1225LM (a resin composition containing a mold release agent, manufactured by Teijin Limited) was used. Except for this point, a POF was produced in the same manner as in Example 1. Regarding Panlite L-1225LM, the molecular weight reduction rate after being exposed to an environment of 85°C and 85% relative humidity for 1000 hours was less than 3%, the same as in Example 1. Also, the MVR was 24 cm 3 / 10 min.

[0137] [Evaluation of Heat Resistance] In the evaluation of the heat resistance of the POFs of Example 1 and Comparative Example 1, the loss of a 40 m POF was measured. Here, regarding the heat resistance of the POF of Example 1, the measurement result of the heat resistance of the POF of Comparative Example 2, which differed only in the presence or absence of a release agent in the resin composition for forming the coating layer, was regarded as the measurement result of the heat resistance of the POF of Example 1. It should be noted that it has been confirmed in advance by preliminary tests that the heat resistance of the POF hardly changes due to only the difference in the presence or absence of a release agent in the resin composition for forming the coating layer. In the evaluation of heat resistance, the POF was held at 105 °C, and the change in loss over time was determined. More specifically, using an optical pulse tester (OTDR: Optical Time Domain Reflectometer) (product name: LOR-220, manufacturer: Luciol Instruments), the loss of the POF was measured at a wavelength of 850 nm and a pulse width of 7 ns, and the change in loss was determined. The POF of Comparative Example 1 showed a loss change (here, it means loss deterioration) of 500 dB / km or more after 300 hours had passed, and no light passed through the 40 m at the time when 600 hours had passed. On the other hand, regarding the result of the heat resistance of the POF of Comparative Example 2, which was regarded as the result of the heat resistance of the POF of Example 1, the loss change (here, it means loss deterioration) of the POF was about 50 dB / km even after 1000 hours had passed.

[0138] [Evaluation of moisture resistance] In the evaluation of the moisture resistance of the POFs of Example 1 and Comparative Example 1, the loss of a 40 m POF was measured. Here, regarding the moisture resistance of the POF of Example 1, the measurement results of the moisture resistance of the POF of Comparative Example 2, which differed only in the presence or absence of a release agent in the resin composition for forming the coating layer, were regarded as the measurement results of the moisture resistance of the POF of Example 1. It should be noted that it has been confirmed in advance by preliminary tests that the moisture resistance of the POF hardly changes due to only the difference in the presence or absence of a release agent in the resin composition for forming the coating layer. In the evaluation of moisture resistance, the POF was held at 85°C and 85% relative humidity, and the change in loss over time was determined. More specifically, the loss was measured and the change in loss was determined by the following method. An OTDR (product name: LOR-220, manufacturer: Luciol Instruments) was prepared. Then, the change in loss was measured under a wavelength of 850 nm and a pulse width of 7 ns. For the POF of Comparative Example 1, the change in loss (here, meaning loss deterioration) exceeded 50 dB / km significantly after 600 hours, and the change in loss (loss deterioration) was close to 100 dB / km at the time point after 1000 hours. On the other hand, for the results of the moisture resistance of the POF of Comparative Example 2, which were regarded as the results of the moisture resistance of the POF of Example 1, the change in loss (here, meaning loss deterioration) of the POF was 55 dB / km or less after 1000 hours. The detailed results are shown in Figure 4. It should be noted that this evaluation was repeated three times for each POF.

[0139] [Evaluation of Foreign Object Generation] For the POFs of Example 1, Comparative Example 1, and Comparative Example 2, the presence or absence of foreign matter generation in the coating layer was confirmed. The specific method is as follows. First, the POF was provided on a linear sensor (product name: LS-9006M, manufacturer: Keyence). Then, in the linear sensor, a portion with relatively large linear variation was cut out to obtain the cut POF. The obtained POF was observed with a microscope (product name: VHX-7000, manufacturer: Keyence). In the POF of Example 1, no foreign matter generation was confirmed in the coating layer. On the other hand, in the POF of Comparative Example 2, the generation of a plurality of black foreign matters was confirmed in the coating layer. Thus, regarding the coating layers of the POFs of Example 1 and Comparative Example 2 formed using resin compositions that differed only in the presence or absence of a release agent, no foreign matter occurred in Example 1 where a resin composition without a release agent was used, while foreign matter occurred in Comparative Example 2 where a resin composition containing a release agent was used. In addition, when evaluating the generation of foreign matter for the POF of Comparative Example 1, no foreign matter generation was confirmed in the coating layer. FIG. 5 is a photograph showing the result of observing the POF of Example 1 with a microscope. FIG. 6 is a photograph showing the result of observing the POF of Comparative Example 2 with a microscope. FIG. 7 is a photograph showing the result of observing the POF of Comparative Example 1 with a microscope.

[0140] [Summary] Summarizing the above results, it becomes as shown in Table 1 below. [Table 1]

[0141] [Supplementary Note] Summarizing the above, one form of the invention of the present disclosure is as follows.

[0142] (1) A plastic optical fiber, wherein the plastic optical fiber has a core, a cladding disposed on the outer periphery of the core, and a coating layer disposed on the outer periphery of the cladding, and is provided with The coating layer is formed of a resin composition, The resin composition, substantially does not contain a release agent, contains a polycarbonate resin including a structural unit represented by the following formula (1), has a glass transition temperature of 130°C or higher and 150°C or lower, and has a water absorption rate of 0.22% or less when exposed to an environment of 23°C and a relative humidity of 50% for 24 hours, a plastic optical fiber.

Chemical formula

[0143] (2) The molecular weight reduction rate of the weight average molecular weight (B) of the resin composition after the resin composition is exposed to an environment of 85°C and a relative humidity of 85% for 1000 hours, with respect to the weight average molecular weight (A) of the resin composition before being exposed to the environment, is 10% or less, The plastic optical fiber according to (1) above.

[0144] (3) The release agent is at least one compound selected from the group consisting of fatty acids, fatty acid ester compounds, modified products of fatty acid ester compounds, polyglycerin fatty acid esters, and sorbitan fatty acid esters, The plastic optical fiber according to (1) or (2) above.

[0145] (4) The release agent is at least one selected from the group consisting of the compound represented by the following formula (2), the compound represented by the following formula (3), and the compound represented by the following formula (4), The plastic optical fiber according to any one of (1) to (3) above.

Chemical formula

Chemical formula

[0146] (5) The melt volume flow rate of the resin composition measured at 300 °C and a load of 1.2 kg in accordance with ISO 1133 is 20 cm 3 / 10 min or more and 26 cm 3 / 10 min or less. The plastic optical fiber according to any one of (1) to (4) above.

[0147] (6) The polycarbonate resin is a compound represented by the following formula (5). The plastic optical fiber according to any one of (1) to (5) above. [Chemical] (However, in the above formula (5), n is an arbitrary integer.)

[0148] (7) The resin composition contains 90% by mass or more of the polycarbonate resin. The plastic optical fiber according to any one of (1) to (6) above.

[0149] (8) The thickness of the coating layer is 50 μm or more and 250 μm or less. The plastic optical fiber according to any one of (1) to (7) above.

[0150] (9) Further provided with a coloring layer disposed so as to cover the coating layer on the outer periphery of the coating layer. The plastic optical fiber according to any one of (1) to (8) above.

[0151] (10) The thickness of the coloring layer is 5 μm or more and 20 μm or less. The plastic optical fiber according to (9) above.

Industrial Applicability

[0152] The POF of the present disclosure has excellent heat resistance and a coating layer capable of suppressing deterioration of loss, and thus is suitable for applications used in high-temperature environments such as in-vehicle use.

Explanation of Signs

[0153] 1a First core material 1b Second core material 1c Cladding material 1d Resin composition 2 Core inner layer part 3 Core outer periphery part 4 Laminate (core) 5 Cladding 6 Coating layer 7 Second laminate 10, 20 POF 11 Core 12 Cladding 13 Coating layer 21 Coloring layer 101a First extruder 101b Second extruder 101c Third extruder 101d Fourth extruder 102a First housing part 102b Second housing part 102c Third housing part 102d Fourth housing part 103a First extrusion part 103b Second extrusion part 103c Third extrusion part 104 Screw 105 Hopper 110 First chamber 120 Diffusion tube 130 Second chamber 140 Third chamber 150 Nozzle 160 Cooling tube 161 Internal space 170 Nip roll 171, 172 Roll 173, 174, 175 Guide roll 176 Take-up roll 180 Displacement gauge 1000 Manufacturing device

Claims

1. A plastic optical fiber, wherein the plastic optical fiber comprises a core, a cladding disposed on the outer periphery of the core, and a coating layer disposed on the outer periphery of the cladding, and the coating layer is formed of a resin composition, the resin composition substantially does not contain a release agent, contains a polycarbonate resin including a structural unit represented by the following formula (1), has a glass transition temperature of 130°C or higher and 150°C or lower, and has a water absorption rate of 0.22% or lower when exposed to an environment of 23°C and 50% relative humidity for 24 hours, a plastic optical fiber. 【Chemical 1】

2. The rate of decrease in the weight average molecular weight (B) of the resin composition after the resin composition is exposed to an environment of 85°C and 85% relative humidity for 1000 hours, relative to the weight average molecular weight (A) of the resin composition before being exposed to the environment, is 10% or lower, The plastic optical fiber according to Claim 1.

3. The release agent is at least one compound selected from the group consisting of fatty acids, fatty acid ester compounds, modified products of fatty acid ester compounds, polyglycerin fatty acid esters, and sorbitan fatty acid esters, The plastic optical fiber according to Claim 1.

4. The release agent is at least one selected from the group consisting of a compound represented by the following formula (2), a compound represented by the following formula (3), and a compound represented by the following formula (4), The plastic optical fiber according to Claim 1. 【Chemical 2】 【Chemical Formula 3】 【Chemical Formula 4】 (However, in the above formulas (2), (3), and (4), R 1 , R 2 , R 3 , R 4 , and R 5 are each independently a linear or branched aliphatic carboxylic acid residue having 5 to 30 carbon atoms.)

5. The melt volume flow rate of the resin composition measured at 300 °C and a load of 1.2 kg in accordance with ISO 1133 is 20 cm 3 / 10 min or more and 26 cm 3 / 10 min or less. The plastic optical fiber according to Claim 1.

6. The polycarbonate resin is a compound represented by the following formula (5), The plastic optical fiber according to Claim 1. 【Chemical Formula 5】 (However, in the above formula (5), n is an arbitrary integer.)

7. The resin composition contains 90% by mass or more of the polycarbonate resin, The plastic optical fiber according to Claim 1.

8. The thickness of the coating layer is 50 μm or more and 250 μm or less, The plastic optical fiber according to Claim 1.

9. Further comprising a coloring layer disposed so as to cover the coating layer on the outer periphery of the coating layer, The plastic optical fiber according to Claim 1.

10. The thickness of the coloring layer is 5 μm or more and 20 μm or less, The plastic optical fiber according to Claim 9.

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