Plastic optical fiber cable

Abstract

To provide a plastic optical fiber cable excellent in long-term heat resistance in a high-temperature environment.SOLUTION: A plastic optical fiber cable includes a core including a polymer having a methyl methacrylate unit and at least one cladding layer provided on an outer peripheral surface of the core, and a coating layer coating an outer peripheral portion of the optical fiber, wherein the coating layer includes a polyamide-based resin (A), and the polyamide-based resin (A) is an aliphatic polyamide resin having an amide group ratio (N1 / N2) which is a ratio of the number of methylene carbon atoms (N1) in the skeleton to the number of amide group carbon atoms (N2) of 7 or more and 10 or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a plastic optical fiber cable. [Background technology]

[0002] A plastic optical fiber strand has a structure in which a core made of transparent resin is surrounded by a cladding layer made of resin with a lower refractive index than the transparent resin, and is a medium that transmits optical signals within the core by reflecting light at the boundary between the core and the cladding layer. Generally, plastic optical fiber strands are used as plastic optical fiber cables in which a coating layer is provided on the outside of the plastic optical fiber strand to prevent physical or chemical damage.

[0003] In recent years, the plastic optical fiber cables have been used for information transmission inside moving objects such as automobiles, or for sensor applications in the food and semiconductor fields, and their use in high-temperature environments where the ambient temperature reaches approximately 100 to 105°C is being considered. Therefore, there is a growing demand for plastic optical fiber cables to have the performance to withstand long-term use in such high-temperature environments.

[0004] However, conventionally known plastic optical fiber cables using polymethyl methacrylate (PMMA) as the core material may have the disadvantage that structural irregularities at the interface between the core and cladding layer of the plastic optical fiber increase and transmission loss increases significantly when used for a long time in a high-temperature environment of around 100 to 105°C. Therefore, there is a problem that it is difficult to use in fields that require long-term heat resistance, as mentioned above.

[0005] In view of these problems, many attempts have been made to improve the heat resistance at around 100 to 105° C. by selecting materials for the cladding and coating layers of plastic optical fiber cables that use PMMA as the core material. For example, a technology has been proposed in which polyamide 12 is used as the coating layer that coats a plastic optical fiber wire, thereby imparting mechanical strength and heat resistance (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-98864 Summary of the Invention [Problem to be solved by the invention]

[0007] However, plastic optical fiber cables, which are constructed by covering a plastic optical fiber strand with polyamide 12, have excellent heat resistance at temperatures of around 85°C, but have the problem that there is room for improvement in terms of long-term heat resistance at temperatures exceeding 100°C.

[0008] Therefore, an object of the present invention is to provide a plastic optical fiber cable that has long-term heat resistance in high-temperature environments exceeding 100° C. without impairing the optical properties of the plastic optical fiber cable. [Means for solving the problem]

[0009] As a result of extensive research into solving the problems of the prior art described above, the inventors have discovered that the problems of the prior art can be solved by using a specific polyamide resin as the material for the coating layer that coats the outer periphery of the optical fiber core, and have thus completed the present invention. That is, the present invention is as follows.

[0010] [1] an optical fiber having a core containing a polymer having a methyl methacrylate unit and one or more cladding layers provided on the outer circumferential surface of the core; a coating layer that coats an outer periphery of the optical fiber; , and the coating layer contains a polyamide-based resin (A), The polyamide resin (A) is an aliphatic polyamide resin having an amide group ratio (N1 / N2), which is the ratio of the number of methylene carbon atoms (N1) in the skeleton to the number of amide group carbon atoms (N2), of 7 to 10. Plastic fiber optic cable. [2] The polyamide resin (A) At least one selected from the group consisting of polyamide 610, polyamide 612, polyamide 810, polyamide 812, polyamide 1010, polyamide 1012, and polyamide 11, The plastic optical fiber cable described in [1] above. [3] The polyamide resin (A) is Density is 1.00g / cm 3 More than 1.40g / cm 3 is as follows: The melting point is 180°C or higher and 230°C or lower. The plastic optical fiber cable according to [1] or [2]. [4] The polyamide resin (A) is It is a polyamide resin derived from plant materials. The plastic optical fiber cable according to any one of [1] to [3]. [5] The polyamide resin (A) is the bio-based carbon content, which is the proportion of the carbon mass of biomass-derived components calculated from radiocarbon (14C) measurements of the total carbon mass constituting the polyamide-based resin (A), is 80 mass% or more; The plastic optical fiber cable according to any one of [1] to [4]. [6] The mass of the total resin constituting the plastic optical fiber cable is The plastic optical fiber cable according to any one of [1] to [5], wherein the biomass plastic content, which is the mass ratio of components derived from plant raw materials, is 25 mass % or more. [7] the cladding layer is made of a fluorine-based resin having a refractive index lower than that of the core; The plastic optical fiber cable according to any one of [1] to [6]. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a plastic optical fiber cable that has excellent long-term heat resistance in a high-temperature environment. [Brief explanation of the drawings]

[0012] [Figure 1] 1 shows a schematic cross-sectional view of an example of a single-core plastic optical fiber cable according to an embodiment of the present invention. [Figure 2] A schematic cross-sectional view of another example of a single-core plastic optical fiber cable of this embodiment is shown. [Figure 3] A schematic cross-sectional view of another example of a multi-core plastic optical fiber cable of this embodiment is shown. [Figure 4] A schematic cross-sectional view of another example of a multi-core plastic optical fiber cable of this embodiment is shown. [Figure 5] A schematic cross-sectional view of another example of a multi-core plastic optical fiber cable of this embodiment is shown. [Figure 6] 1 is a schematic cross-sectional view of an example of a two-core plastic optical fiber cable according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. The following embodiments are merely examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be implemented by appropriately modifying it within the scope of its gist. In the drawings, duplicated explanations of identical elements will be omitted. Furthermore, unless otherwise specified, the positional relationships, such as up, down, left, and right, are based on the positional relationships shown in the drawings. Furthermore, the dimensional ratios of the drawings are not limited to the ratios shown in the drawings.

[0014] [Plastic optical fiber cable] The plastic optical fiber cable (hereinafter sometimes referred to as POF cable) of this embodiment has an optical fiber wire having a core containing a polymer having methyl methacrylate units and one or more cladding layers provided on the outer surface of the core, and a coating layer that coats the outer periphery of the optical fiber wire. The coating layer contains a polyamide-based resin (A), and the polyamide-based resin (A) is an aliphatic polyamide resin having an amide group ratio (N1 / N2), which is the ratio of the number of methylene carbon atoms (N1) in the skeleton to the number of amide group carbon atoms (N2), of 7 or more and 10 or less. With the above-described configuration, a plastic optical fiber cable having excellent long-term heat resistance in a high-temperature environment can be obtained.

[0015] 1 to 6 show schematic cross-sectional views of an example of the POF cable of this embodiment.

[0016] FIG. 1 is a schematic cross-sectional view of an example of the POF of this embodiment. The POF cable 10 is a single-core plastic optical fiber cable having one core 12 . The POF cable 10 has a core 12 at the center, a clad layer 14 formed to cover the outer periphery of the core 12, and a coating layer 18 formed to cover the outer periphery of the clad layer 14. In this embodiment, the core 12 and the cladding layer 14 are collectively referred to as a plastic optical fiber 16 . Although not shown, an outer coating layer may be further provided on the outer periphery of the coating layer 18. This makes it possible to more reliably protect the plastic optical fiber from the effects of long-term outdoor use and contact with chemicals, etc.

[0017] FIG. 2 is a schematic cross-sectional view of another example of the POF cable of the present embodiment. As shown in FIG. 2, the POF cable 20 has a core 22 in the center, a clad layer 24 formed around the outer periphery of the core 22, a protective layer 28 formed around the outer periphery of the clad layer 24, and a coating layer 29 formed around the outer periphery of the protective layer 28. The core 22, the cladding layer 24, and the protective layer 28 constitute a plastic optical fiber strand 26. Since the POF cable 20 further has a protective layer 28 formed on the outer periphery of the cladding layer 24, the plastic optical fiber strand 26 can be more reliably protected from the effects of long-term outdoor use and contact with chemicals, etc.

[0018] FIG. 3 is a schematic cross-sectional view of another example of the POF cable of the present embodiment. As shown in FIG. 3, the POF cable 30 is a multi-core plastic optical fiber cable having a plurality of cores 32. The POF cable 30 is a seven-core optical fiber cable, but is not limited to seven cores. The POF cable 30 is multi-cored with seven cores 32 covered with a clad layer 34. The cores 32 and the clad layer 34 constitute a plastic optical fiber strand 36. The clad layer 34 is covered with a coating layer 38. Although not shown, an outer coating layer may be further provided on the coating layer 38. This can more reliably protect the cores 32 from the effects of long-term outdoor use and contact with chemicals, etc.

[0019] FIG. 4 is a schematic cross-sectional view of another example of the POF cable of the present embodiment. As shown in FIG. 4, in a POF cable 40, each core 42 is individually covered with a cladding layer 44. The POF cable 40 has cores 42 each covered with a first clad layer 441, which are then covered with a second clad layer 442, thereby forming a multi-core cable. A coating layer 48 is formed on the outer periphery of the second cladding layer 442. The core 42, the first cladding layer 441, and the second cladding layer 442 constitute a plastic optical fiber wire 46.

[0020] FIG. 5 is a schematic cross-sectional view of another example of the POF cable of the present embodiment. 5, a POF cable 50 is configured as a multi-core cable with seven cores 52 covered with a cladding layer 54. A protective layer 58 is provided on the outer periphery of the cladding layer 54, constituting a plastic optical fiber strand 56. A coating layer 59 is then formed on the outer periphery of the protective layer 58. The POF cable 50 is a seven-core optical fiber cable, but is not limited to seven cores.

[0021] FIG. 6 is a schematic cross-sectional view of the two-core structure of the POF cable of this embodiment. The POF cable 60 is a single-core pair optical fiber cable having two cores 62a and 62b. The POF cable 60 has cores 62a and 62b therein, clad layers 64a and 64b that cover the outer peripheries of the cores 62a and 62b, and a coating layer 68 that covers the outer peripheries of the clad layers 64a and 64b. In this embodiment, the core 62a and the cladding layer 64a together constitute a plastic optical fiber strand 66a, and the core 62b and the cladding layer 64b together constitute a plastic optical fiber strand 66b. Although not shown, an outer coating layer may be further provided on the outer periphery of the coating layer 68. This makes it possible to more reliably protect the cores 62a and 62b from the effects of long-term outdoor use and chemicals with which they come into contact.

[0022] The components and materials constituting the above-mentioned POF cable will be described in detail below.

[0023] (core) The resin constituting the core (hereinafter also referred to as "core resin") contains a polymer having a methyl methacrylate unit. The resin constituting the core is preferably a transparent resin. As the core resin, any of those known as core resins for plastic optical fibers can be used. As the core resin, for example, polymethyl methacrylate resins are preferred, and polycarbonate resins may be included. Among these, polymethyl methacrylate resins are preferred from the viewpoint of transparency.

[0024] The polymethyl methacrylate resin refers to a homopolymer of methyl methacrylate or a copolymer containing 50% by mass or more of methyl methacrylate monomer. That is, the polymethyl methacrylate resin may be a copolymer of methyl methacrylate monomer and another monomer copolymerizable with methyl methacrylate monomer. The other monomer copolymerizable with the methyl methacrylate monomer is not particularly limited, but examples thereof include acrylic acid esters such as methyl acrylate, ethyl acrylate, and butyl acrylate; methacrylic acid esters such as ethyl methacrylate, propyl methacrylate, and cyclohexyl methacrylate; maleimides such as isopropylmaleimide; acrylic acid, methacrylic acid, styrene, etc. The other copolymerizable monomers may be used alone or in combination of two or more.

[0025] The weight-average molecular weight of the polymethyl methacrylate resin is not particularly limited, but from the viewpoint of moldability, it is preferably from 80,000 to 200,000, more preferably from 100,000 to 120,000. The weight-average molecular weight can be measured by a conventionally known GPC (gel permeation chromatography) method.

[0026] (cladding layer) The cladding layer is formed to cover the outer periphery of the core. The optical signal propagates through the optical fiber by being reflected at the interface between the cladding layer and the core. From this perspective, it is preferable that the cladding layer directly covers the surface of the core. The cladding layer may be a single layer or two or more layers. In the case of a multiple layer configuration, for example, when the optical fiber has a first cladding layer that directly covers the core and a second cladding layer that covers the outer periphery of the first cladding layer, it is preferable that the refractive index of the second cladding layer located on the outer side is lower than that of the first cladding layer located on the inner side. This makes it possible to recover a portion of the optical signal that has penetrated the first cladding layer by interfacial reflection between the first cladding layer and the second cladding layer. Therefore, in the case of a multiple cladding layer configuration, it is preferable that the refractive index of the cladding layer located on the inner side is lower than that of the cladding layer located on the outer side.

[0027] The resin constituting the cladding layer (hereinafter also referred to as "cladding resin") is not particularly limited, but specifically, fluororesins having a lower refractive index than the core are preferred. Among these, fluororesins having a high light transmittance are particularly preferred. By using such fluororesins, transmission loss can be further reduced.

[0028] Examples of fluorine-based resins include fluoromethacrylate polymers, polyvinylidene fluoride resins, and ethylene-tetrafluoroethylene copolymers. The fluorinated methacrylate polymer is not particularly limited, but from the viewpoint of high transmittance and excellent heat resistance and moldability, fluorine-containing acrylate or methacrylate monomers such as fluoroalkyl methacrylate, fluoroalkyl acrylate, and α-fluoro-fluoroalkyl acrylate are preferred. Furthermore, the polymer may be a copolymer containing units derived from a fluorine-containing (meth)acrylate monomer and units derived from another component copolymerizable therewith, and a copolymer with units derived from a copolymerizable hydrocarbon-based monomer such as methyl methacrylate is preferred. A copolymer of units derived from a fluorine-containing (meth)acrylate monomer and units derived from a hydrocarbon-based monomer copolymerizable therewith is preferred because it allows for control of the refractive index.

[0029] The polyvinylidene fluoride resin is not particularly limited, but from the viewpoint of excellent heat resistance and moldability, preferred are: a homopolymer of vinylidene fluoride; a copolymer of vinylidene fluoride with at least one monomer selected from the group consisting of tetrafluoroethylene, hexafluoropropene, trifluoroethylene, hexafluoroacetone, perfluoroalkyl vinyl ether, chlorotrifluoroethylene, ethylene, and propylene; and an alloy of a polymer containing units derived from these vinylidene fluoride components with a PMMA resin.

[0030] Furthermore, from the viewpoint of heat resistance, the fluorine-based resin constituting the cladding layer is preferably a copolymer of polyvinylidene fluoride, hexafluoropropene, and tetrafluoroethylene, more preferably a copolymer consisting of 40 mol% to 62 mol% of vinylidene fluoride, 28 mol% to 40 mol% of tetrafluoroethylene, and 8 mol% to 22 mol% of hexafluoropropene. Furthermore, among the copolymers, resins satisfying the following conditions are preferred, because they facilitate the production of optical fibers: a refractive index measured at 20°C with sodium D line of 1.35 to 1.37, a Shore D hardness (ASTM D2240) at 23°C of 38 to 45, and an MFR (ASTM D1238, 10 kg load) at 240°C of 5 g / 10 min to 100 g / 10 min. The copolymer of polyvinylidene fluoride, hexafluoropropene, and tetrafluoroethylene may be a copolymer with trifluoroethylene, hexafluoroacetone, perfluoroalkyl vinyl ether, chlorotrifluoroethylene, ethylene, propylene, or the like, as long as the component ratios are within the above range.

[0031] The ethylene-tetrafluoroethylene copolymer as the fluorine-based resin constituting the cladding layer is not particularly limited, but is preferably a modified fluorine-based resin such as a modified ethylene-tetrafluoroethylene copolymer resin, which has a melting point in the range of 150 to 200°C, a refractive index measured at 20°C with sodium D line of 1.37 or more and 1.41 or less, an MFR (230°C, load 3.8 kg, orifice diameter 2 mm, length 8 mm) of 5 g / 10 min or more and 100 g / 10 min or less, and has a reactive functional group terminal. The modified fluororesin is a polymer of an ethylenic monomer (which may contain halogen atoms other than fluorine, such as chlorine; hereinafter also referred to as a "fluorine-containing monomer") in which all or some of the hydrogen atoms have been substituted with fluorine atoms, or a copolymer of the fluorine-containing monomer and a monomer copolymerizable therewith, which has been modified by introducing a reactive functional group (e.g., a carbonate group (carbonyldioxy group), an ester group, a haloformyl group, a carboxyl group, etc.) into the main chain or side chain, thereby having a reactive functional group terminal. Here, "having a reactive functional group terminal" means having a reactive functional group at the terminal of the main chain and / or side chain.

[0032] As described above, by using a modified fluororesin into which a reactive functional group has been introduced, an optical fiber having excellent chemical resistance, heat resistance, etc. can be obtained. From the viewpoint of chemical resistance and heat resistance, among the reactive functional groups, those having a carbonate group are particularly preferable. The modified fluororesin into which a reactive functional group having a carbonate group has been introduced can be easily introduced by using peroxycarbonate as a polymerization initiator during polymerization of the modified fluororesin.

[0033] The introduction of reactive functional groups into the fluororesin can be carried out by a known method. For example, a method of introducing reactive functional groups into a copolymer by using a predetermined polymerization initiator is preferred. Specifically, it is preferred to introduce reactive functional groups into the fluororesin using 0.05 to 20 parts by mass of the polymerization initiator per 100 parts by mass of the resulting fluororesin.

[0034] The modified fluorine-based resin preferably has an ethylene-tetrafluoroethylene copolymer as the main skeleton. The molar ratio of ethylene / tetrafluoroethylene in the ethylene-tetrafluoroethylene copolymer is not particularly limited, but is preferably in the range of 70 / 30 to 30 / 70 from the viewpoint of the balance between moldability and chemical resistance.

[0035] The modified fluorine-based resin having an ethylene-tetrafluoroethylene copolymer as a main skeleton may be further copolymerized with other monomers copolymerizable with tetrafluoroethylene and ethylene (for example, olefins such as hexafluoropropylene, hexafluoroisobutene, propylene, 1-butene, 2-butene, vinyl chloride, vinylidene chloride, vinylidene fluoride, chlorotrifluoroethylene, vinyl fluoride, hexafluoroisobutene, and perfluoro(alkyl vinyl ether)).

[0036] In this case, the molar ratio of ethylene / tetrafluoroethylene / other copolymerizable monomer is not particularly limited, but from the viewpoint of the balance between moldability and chemical resistance, it is preferably in the range of (10 to 80) / (20 to 80) / (0 to 40).

[0037] More preferred examples of the modified fluororesin include a carbonyldioxy group-containing copolymer having a polymer chain obtained from a monomer component consisting of 62 mol % to 80 mol % of tetrafluoroethylene, 20 mol % to 38 mol % of ethylene, and 0 mol % to 10 mol % of a monomer copolymerizable therewith; and a carbonyldioxy group-containing copolymer having a polymer chain obtained from a monomer component consisting of 20 mol % to 80 mol % of tetrafluoroethylene, 10 mol % to 80 mol % of ethylene, 0 mol % to 30 mol % of hexafluoropropylene, and 0 mol % to 10 mol % of a monomer copolymerizable therewith. The above-mentioned modified fluorine-based resin is preferable because it has particularly excellent chemical resistance and heat resistance.

[0038] The melting point of the modified fluororesin is preferably in the range of 150°C to 200°C. This is preferable because a melting point in this temperature range allows molding at a molding temperature of 300°C or less, which is an allowable temperature for thermal decomposition of the polymethyl methacrylate resin that is the core resin. The melting point can be measured by differential scanning calorimetry. For example, the melting point can be measured by using a differential scanning calorimeter (EXSTAR DSC6200) manufactured by Seiko Instruments Inc., by heating the sample at a heating rate of 20°C / min.

[0039] The modified fluorine-based resin used as the material for the cladding layer constituting the plastic optical fiber cable of this embodiment is preferably an ethylene-tetrafluoroethylene copolymer resin having a terminal reactive functional group. The ethylene-tetrafluoroethylene copolymer resin may be a copolymer of tetrafluoroethylene, ethylene, and a monomer such as propylene. Among these, those having a melting point in the range of 150°C to 200°C and an MFR (230°C, load 3.8 kg) in the range of 5 to 100 g / 10 min are preferred because they can be molded at a molding temperature of 300°C or less, which is an acceptable temperature for thermal decomposition of the polymethyl methacrylate resin constituting the core. The ethylene-tetrafluoroethylene copolymer resin having a terminal reactive functional group typically has a Shore D hardness (ASTM D2240) value at 23°C in the range of 60 to 80. Introducing a reactive functional group into the cladding resin provides adhesion to the core, making it difficult for even a hard cladding resin to peel from the core, and thus reducing the likelihood of the core protruding from the cladding layer.

[0040] Commercially available modified fluororesins constituting the cladding layer as described above include Neoflon EFEP RP5000 and RP4020 manufactured by Daikin Industries, Ltd., and Fluon LM-ETFE AH2000 manufactured by Asahi Glass Co., Ltd. Of these, Neoflon EFEP RP5000 and RP4020 are preferred because they are carbonate-modified ethylene-tetrafluoroethylene copolymers whose reactive functional groups contain carbonyldioxy groups.

[0041] In the plastic optical fiber cable of this embodiment, the thickness of the cladding layer is not particularly limited, but from the viewpoint of sufficiently reflecting light, suppressing a decrease in the light-receiving area, and ensuring practically sufficient mechanical strength, the cladding layer in contact with the core is preferably 1 μm to 100 μm, more preferably 5 μm to 50 μm. If there are other cladding layers in addition to the cladding layer in contact with the core, the thickness of these other cladding layers does not affect the mechanical strength, so is preferably 1 μm to 20 μm, more preferably 1 μm to 10 μm.

[0042] The diameter of a single-core POF wire composed of a core and a cladding layer is not particularly limited, but is typically in the range of 200 μm to 3000 μm, and the total thickness of the cladding layer 14 is preferably in the range of 5 μm to 50 μm. If the cladding layer is 5 μm or thicker, the mechanical strength and heat resistance of the POF wire or POF cable can be further improved. Furthermore, if the cladding layer is 50 μm or thicker, a sufficient cross-sectional area of ​​the core that functions as an optical fiber can be ensured, allowing optical signals to propagate sufficiently.

[0043] (protective layer) The plastic optical fiber of this embodiment preferably has a protective layer 28 on the outer periphery of the cladding layer 24 that forms the outermost periphery of the core / cladding structure, as shown in Fig. 2. By providing the protective layer 28 on the outer periphery of the cladding layer 24, it is possible to improve adhesion with the coating layer 29 described below and to impart heat resistance to the plastic optical fiber, thereby further improving the performance of the plastic optical fiber.

[0044] The material used for the protective layer 28 is not particularly limited as long as it is a thermoplastic resin that can be spun together with the material that forms the core / clad structure of this embodiment. From the viewpoints of adhesion to the clad layer 24 and moldability, however, a thermoplastic fluorine-based resin is preferred, and the above-mentioned ethylene-tetrafluoroethylene copolymer is more preferred. It is particularly preferable to form the protective layer 28 as a layer having a lower refractive index than the clad layer 24. By using a material having a lower refractive index than the clad layer 24, the protective layer 28 can function as a second clad layer when the clad layer 24 is used as a first clad layer, and the protective layer 28, which is a low refractive index layer, can reflect light leaking from the first clad 24, thereby achieving the above-mentioned effect. The material of the protective layer 28, which is a low refractive index layer, is not particularly limited as long as it has a refractive index lower than that of the material of the clad layer 24. The thickness of the protective layer 28 is preferably 1 μm or more and 20 μm or less, and more preferably 1 μm or more and 10 μm or less, in order to impart appropriate mechanical strength without reducing the light intensity of the plastic optical fiber.

[0045] (covering layer) The POF cable of this embodiment has a configuration in which the outer periphery of a bare fiber is covered with a covering layer. In this embodiment, the resin constituting the coating layer (hereinafter also referred to as "coating resin") contains a predetermined polyamide resin (A). The polyamide resin (A) is not particularly limited as long as its starting material falls within the range of the specified physical properties of the present invention, whether it is derived from petroleum or from a plant material as described below. The polyamide resin (A) used in the coating layer constituting the POF cable of this embodiment has an amide group ratio (N1 / N2), which is the ratio of the number of methylene carbon atoms (N1) in the skeleton to the number of amide group carbon atoms (N2), of 7 to 10.

[0046] The polyamide resin (A) used in the coating layer has a density of 1.00 g / cm 3 More than 1.40g / cm 3 Preferably, it is 1.01 g / cm or less. 3 More than 1.20g / m 3 More preferably, it is 1.03 g / cm or less. 3 More than 1.15g / cm 3 It is even more preferable that: The density of polyamide resin (A) is 1.00 g / cm 3This is preferable because it provides sufficient mechanical strength when used as a material for the coating layer of a POF cable. 3 If the thickness is less than or equal to the above, sufficient flexibility can be obtained when the POF cable is made, which is preferable.

[0047] The melting point of the polyamide resin (A) used in the coating layer is preferably 180°C or higher and 230°C or lower, more preferably 185°C or higher and 225°C or lower, and even more preferably 187°C or higher and 220°C or lower. If the melting point of the polyamide resin (A) is 180°C or higher, the POF cable can withstand use in a high temperature range exceeding 100°C, and is also excellent in long-term heat resistance, which is preferable. Furthermore, if the melting point is 230° C. or less, it is possible to coat the POF wires without causing thermal damage to the POF wires when manufacturing a POF cable, which is preferable.

[0048] (Amide group ratio) The ratio of the number of methylene carbon atoms in the polymer skeleton of the polyamide to the number of amide group carbon atoms is used as an index for determining the physical properties of the polyamide resin (A) used in the coating layer constituting the plastic optical fiber cable of this embodiment. The ratio (N1 / N2) of the number of methylene carbon atoms (N1) to the number of amide group carbon atoms (N2) in the polymer skeleton of the polyamide resin (A) (hereinafter referred to as "amide group ratio") is 7 or more and 10 or less, and preferably 8 or more and 9 or less. Here, the amide group ratio can be expressed by the ratio of the number of carbon atoms in the amide group contained in the structural unit of the polyamide resin (A), and can be calculated by the following mathematical formula (1). The amide group ratio is an index of the reciprocal of the amide group concentration, with the number of methylene carbon atoms in the polymer skeleton as the numerator and the number of amide group carbon atoms as the denominator, so a small value means a high amide group concentration. Formula (1): Amide group ratio = number of methylene carbons per structural unit / number of amide group carbons per structural unit The amide group ratio can be measured by the method described in the Examples below.

[0049] In the above formula (1), the "structural unit" refers to a repeating structural unit that constitutes the polyamide resin (A). The "number of amide group carbon atoms per structural unit" refers to the total number of carbon atoms in the amide groups contained in the structural unit. The "number of methylene carbon atoms" refers to the total number of carbon atoms in the methylene groups contained in the structural unit.

[0050] Generally, polyamide resins include L-type polyamide resins, which contain cyclic lactams or amino acids as constituent components, depending on the monomers used in polymerization, and NM-type polyamide resins obtained by condensation polymerization of diamine N1 and dicarboxylic acid M1 or condensation polymerization of different amino acids (amino acid N2 and amino acid M2). L-type polyamide resins contain one amide group in the structural unit, and the total number of carbon atoms in the methylene groups is the number of carbon atoms in the lactam minus one. On the other hand, since MN type polyamide resins contain two amide groups in the structural unit, the total number of carbon atoms in the methylene groups is the total number of carbon atoms in the diamine and dicarboxylic acid minus 2. For example, when applied to the above formula (1), polyamide 12 has one amide group in the structural unit and a total of 11 carbon atoms in the methylene group, so the amide group ratio is 11. In the case of polyamide 66, since the structural unit contains two amide groups, the total number of carbon atoms in the methylene groups is 10, which is the total number of carbon atoms in the hexamethylenediamine and adipic acid that make up polyamide 66 minus 2. Therefore, the amide group ratio is 5.

[0051] The smaller the amide group ratio, the higher the amide group concentration in the polyamide-based resin, which makes it easier for hydrogen bonds to form between the amide groups, resulting in a higher crystallinity and melting point, and a tendency for the polyamide-based resin to have excellent mechanical strength and gas barrier properties for oxygen, etc. On the other hand, if the amide group ratio is too small, the polyamide-based resin becomes rigid and its flexibility decreases. By specifying the amide group ratio of the polyamide resin (A), which is the material for the coating layer of the POF cable of this embodiment, within the above range, it is possible to impart sufficient mechanical strength and sufficient long-term heat resistance in high-temperature environments exceeding 100°C without impairing the optical properties of the plastic optical fiber when coating the plastic optical fiber wire.

[0052] The amide group ratio of 7 or more is preferable because it can prevent the polyamide resin (A) from becoming rigid and ensure sufficient flexibility as a POF cable. Furthermore, the amide group ratio of 7 or more can prevent the melting point of the polyamide resin from becoming too high, avoiding thermal damage to the bare plastic optical fiber when coating the bare plastic optical fiber with the coating resin, and ensuring sufficient optical properties. Furthermore, by making the amide group ratio 10 or less, the ratio of methylene groups to amide groups in the polyamide resin (A) is reduced, so that desired heat resistance and mechanical strength can be obtained when made into a POF cable.

[0053] The polyamide-based resin (A) used in this embodiment is not particularly limited as long as it satisfies the above conditions, but particularly preferred are polyamide 610 (amide group ratio = 7), polyamide 612 (amide group ratio = 8), polyamide 810 (amide group ratio = 8), polyamide 812 (amide group ratio = 9), polyamide 1010 (amide group ratio = 9), polyamide 1012 (amide group ratio = 10), polyamide 11 (amide group ratio = 10), etc.

[0054] The amide group ratio of the polyamide resin (A) can be determined by the above formula (1) by identifying its structural units using a general analytical method such as GPC or pyrolysis MS-GC. The polyamide resin (A) having an amide group ratio of 7 or more and 10 or less can be obtained by a known method. For example, polyamide 11 having an amide group ratio of 10 as the above-mentioned L-type polyamide resin can be obtained by condensation polymerization of 11-aminoundecanoic acid, which is a type of amino acid. As an NM type polyamide resin, polyamide 1010 (amide group ratio = 9) can be obtained by condensation polymerization of decanediamine and sebacic acid. Furthermore, polyamide 612 (amide group ratio = 8) can be obtained by condensation polymerization of amino acids, such as caprolactam and lauryllactam. Furthermore, polyamide 610 (amide group ratio = 7) can be obtained by condensation polymerization of hexamethylenediamine and sebacic acid.

[0055] (Plant-derived polyamide resin) Furthermore, the polyamide resin (A) is preferably a bio-based polyamide resin made from a plant-derived component as a starting material, ie, a plant-derived polyamide resin, as shown below. A method for producing this bio-based polyamide resin will now be described. First, castor oil is used as the starting material. The oil extracted from this material is separated from unnecessary impurities to produce ricinoleic acid triglyceride contained in the oil. This ricinoleic acid triglyceride is then subjected to processes such as transesterification to synthesize dicarboxylic acid compounds such as aminoundecanoic acid and sebacic acid, and diamine compounds, which are used as raw materials for polyamide resins. The resulting monomers are then subjected to condensation polymerization in the presence of a polymerization catalyst to produce polyamide. The plant-derived polyamide resins obtained in this manner have been confirmed to have similar quality and processability to conventional petroleum-derived polyamide resins.

[0056] When the POF cable of this embodiment uses the above-mentioned plant-derived polyamide resin, it can be manufactured by the same method as when a conventional petroleum-derived polyamide resin is used.

[0057] In the POF cable of this embodiment, by using a polyamide-based resin derived from plant materials that has the above-mentioned specific amide group ratio and is obtained as described above, the cable has the desired heat resistance and mechanical properties, while making it possible to save petroleum resources by replacing conventional petroleum-derived resin compositions and contributing to environmental improvement by reducing carbon dioxide emissions.

[0058] The polyamide-based resin derived from the above-mentioned plant raw materials preferably has the density and melting point described above, and is not particularly limited as long as it has the above-mentioned amide group ratio, but examples include polyamide 11 (amide group ratio = 10), polyamide 610 (amide group ratio = 7), polyamide 612 (amide group ratio = 8), polyamide 810 (amide group ratio = 8), polyamide 812 (amide group ratio = 9), polyamide 1010 (amide group ratio = 9), polyamide 1012 (amide group ratio = 10), etc.

[0059] The plant-derived polyamide resins described above can be easily used to coat POF wires, just like conventional petroleum-derived polyamides. Furthermore, the use of plant-derived polyamide resins can provide the same moldability and sufficient strength against tension, bending, torsion, impact, etc. as POF cables coated with conventional petroleum-derived polyamide resins.

[0060] (Bio-based carbon content of polyamide resin (A)) The polyamide resin (A) used in the coating layer of the POF cable of this embodiment preferably has a bio-based carbon content (biomass ratio), which is the ratio of the carbon mass of biomass-derived components calculated from a radiocarbon (14C) measurement value to the total carbon mass constituting the polyamide resin (A), of 80 mass% or more, more preferably 85 mass% or more, and even more preferably 100 mass%.

[0061] Here, the biomass degree of the polyamide resin (A) will be explained. Generally, if the manufacturing process is the same, plant-based resin compositions and petroleum-based resin compositions do not differ in mechanical properties (e.g., molecular weight, crystallinity, etc.) resulting from polymer structure, or in thermal properties (e.g., melting point). Therefore, to distinguish between the two, the biomass ratio is measured by measuring the content of the radioactive isotope 14C. This 14C is contained only in plant-based raw materials because plants absorb atmospheric 14C when they absorb carbon dioxide from the atmosphere for growth. On the other hand, the carbon in petroleum-based resin compositions does not contain radioactive carbon (14C). Therefore, the concentration of radioactive carbon (14C) can be measured using accelerator mass spectrometry to calculate the proportion of plant-based resin compositions in a resin composition.

[0062] This bio-based carbon content can be measured using the method described in ISO 16620-2. First, the sample to be measured is burned to generate carbon dioxide, which is then purified in a vacuum line. The carbon dioxide is then reduced with hydrogen using iron as a catalyst to generate graphite, which is then attached to a dedicated 14C-AMS device to measure the 14C count, 13C concentration (13C / 12C), and 14C concentration (14C / 12C). From these measurements, the ratio of the 14C concentration of the sample carbon to standard modern carbon can be calculated.

[0063] In this embodiment, by forming a coating layer using the polyamide-based resin (A) derived from plant raw materials as described above, it is possible to reduce the amount of carbon dioxide emitted during the production of the polyamide-based resin, which is the raw material for the cable material, and as a result, it is possible to reduce the generation of carbon dioxide during the production of the POF cable.

[0064] Furthermore, by using a polyamide-based resin derived from plant-based raw materials having a predetermined biomass degree calculated from the measurement value of radiocarbon dating 14C as the polyamide-based resin (A) constituting the coating layer of the POF cable of this embodiment, the biomass degree can be used as an indicator to identify the origin of the raw material of the polyamide-based resin constituting the coating layer for various types of POF cables included in this embodiment.

[0065] (Biomass plastic content) In addition, in the POF cable of this embodiment, the biomass plastic content relative to the mass of all resins constituting this POF cable is preferably 25% by mass or more, more preferably 27% by mass or more, and even more preferably 30% by mass or more.

[0066] The biomass plastic content is the mass ratio of components derived from plant raw materials, and is an index showing the extent to which biomass plastics are used in all resin components constituting the POF cable.

[0067] In the POF cable of this embodiment, the cross-sectional diameter of the POF wire is preferably 0.5 mm or more and 1.0 mm or less, and the coating layer is preferably made of a polyamide resin derived from plant-based raw materials. The thickness of the coating layer is preferably 100 μm or more. By adopting such a configuration, the biomass plastic content of the POF cable can be increased to 25 mass % or more, which makes it possible to suppress the generation of carbon dioxide and reduce the environmental burden.

[0068] In the POF cable of this embodiment, the plant-derived polyamide resin (A) may contain a light-blocking agent such as carbon black or a flame retardant such as melamine cyanurate to prevent external light from entering the POF wire, as long as the biomass plastic content of the POF cable does not fall below 25% by mass. Furthermore, a colorant may be contained in the material forming the coating layer to enhance the distinguishability and design of the POF cable. Known dye-based or inorganic colorants are used as colorants, but inorganic pigments are preferred from the viewpoint of heat resistance.

[0069] The polyamide resin (A) and the additives may be mixed, for example, by melt-kneading using a known device such as a twin-screw extruder.

[0070] The temperature for melt-kneading the materials constituting the coating layer is preferably 180°C or higher and 250°C or lower, more preferably 190°C or higher and 230°C or lower. When the temperature for melt-kneading the materials constituting the coating layer is 180°C or higher, the additives can be uniformly dispersed in the polyamide-based resin (A), and sufficient mechanical strength can be achieved. When the temperature for melt-kneading the materials constituting the coating layer is 250°C or lower, the polyamide-based resin (A) can be kneaded without impairing its inherent performance.

[0071] The coating layer can be formed by a method commonly used for cable-making POF wires, but a method of forming the coating layer using a crosshead die is preferred because it allows the production of a POF cable that fully exhibits the effects of the present invention. [Example]

[0072] Hereinafter, the present embodiment will be described with reference to specific examples and comparative examples, but the present embodiment is not limited to the examples described below. First, the evaluation methods used in the examples and comparative examples of the present invention will be described.

[0073] (refractive index) A film-like test piece having a thickness of 200 μm was prepared by melt pressing using the core resin and clad layer resin used in the examples and comparative examples described below. The refractive index (nD20) of sodium D line at 20° C. was measured using an Abbe refractometer.

[0074] (The ratio of the number of methylene carbon atoms (N1) in the skeleton of the resin in the coating layer to the number of amide group carbon atoms (N2), the amide group ratio (N1 / N2)) For polyamide resins having known structural units, which will be described later, the number of amide groups and the number of methylene groups per structural unit were calculated from the structural units, and the amide group concentration was determined by the following formula (1). Formula (1): Amide group ratio = number of methylene carbons per structural unit / number of amide group carbons per structural unit

[0075] (Transmission loss) Using the POF cables manufactured in the examples and comparative examples described below, transmission loss was measured by a 25 m-1 m cutback method under conditions of a measurement wavelength of 650 nm and an excitation NA of 0.15.

[0076] (Transmission loss after 3000 hours) 25 m of POF cables manufactured in the examples and comparative examples described below were wound in a reel and left to stand in three different environments: a dry heat environment at 85°C, a dry heat environment at 105°C, and a humid heat environment at 85°C and 85% RH, and the transmission loss after 3000 hours was measured. The measurement conditions were a measurement wavelength of 650 nm, excitation NA=0.15, and the transmission loss was measured by a 25 m-1 m cutback method.

[0077] (bio-based carbon content) The concentrations of carbon (12C) and other isotopes contained in the polyamide were measured using the method described in ISO 16620-2, and the proportion of radioactive carbon (14C) in the total carbon constituting the polyamide was calculated. From this, the biobased carbon content (mass%), which is the mass proportion of carbon from biomass-derived components, was measured.

[0078] (Biomass plastic content) The biomass plastic content of the POF cables produced in the examples and comparative examples described below was calculated as the ratio of the mass of biomass-derived polyamide to the mass of all resins constituting the POF cable. The mass of 1 m of POF cable was measured, and then it was disassembled into the coating layer and the plastic optical fiber, and the mass of the coating layer was measured. When the coating layer contained a light-shielding material, a colorant, or other additives, the mass of the biomass-derived polyamide contained in the coating layer was calculated based on the blending ratio of these additives. Finally, the mass proportion (mass %) of the biomass-derived polyamide was calculated from the calculated mass of the biomass-derived polyamide and the mass of the plastic optical fiber that had been weighed in advance.

[0079] (tensile breaking strength) The maximum breaking strength when the POF cable broke was measured in accordance with the method of ASTM D1708 at a temperature of 23°C and a pulling speed of 100 mm / min.

[0080] (Number of repeated bending times) A load of 500 gf was applied to one end of a 3-m-long POF cable, and the center of the POF cable was clamped between two 15-mm-diameter circular pipes. The other end of the POF cable was moved to one of the circular pipes and wrapped around the outer periphery of the circular pipe so that the POF cable was bent 90 degrees, and then moved to the other circular pipe and wrapped around the outer periphery of the circular pipe so that the POF cable was bent 90 degrees, for a total of 180 degrees of bending. This process was repeated, and the number of bends until the POF cable broke was measured.

[0081] (heat shrinkage rate) At room temperature (23°C), the POF cable was cut to a length of 1 m using an industrial razor so that both ends were flat, then heated at 105°C for 1 hour, cooled to room temperature, and the cable length was measured. The shrinkage rate was calculated using the following formula. A score of 4% or less was considered acceptable. Heat shrinkage rate = (1m - cable length after test) / 1m x 100 (%)

[0082] Example 1 The core resin used was a polymethyl methacrylate resin with a refractive index of 1.492, a weight-average molecular weight of 100,000, and an MFR of 1.5 g / 10 min, and the clad resin in contact with the core was a copolymer of ethylene, tetrafluoroethylene, and hexafluoropropene (refractive index 1.362). These resins were melted and fed into a spinning head at 220°C. They were then melt-spun into composite fibers using a concentric composite nozzle. The fibers were then stretched twice in the fiber axis direction in a hot air oven at 150°C to obtain a POF strand with a clad resin thickness of 10 μm and a diameter of 1.0 mm.

[0083] Next, a polyamide-based resin composition was prepared by adding 3 parts by mass of carbon black as a colorant to 100 parts by mass of commercially available polyamide 1010 (d=1.05, melting point 200°C, amide group ratio=9, bio-based carbon content 0% by mass) using a twin-screw extruder with a screw diameter of 30 mm, and the mixture was melt-kneaded at 240°C to obtain a resin composition. Next, the POF wire obtained as described above was coated with the resin composition at 220°C using a single-screw extruder with a screw diameter of 40 mmφ and a crosshead die, to a thickness of 0.25 mm, thereby obtaining a POF cable. The resulting POF cable had a diameter of 1.5 mm. The biomass plastic content of the produced POF cable was 0% by mass.

[0084] Example 2 A POF wire having a diameter of 1.0 mm was obtained in the same manner as in Example 1. Next, a polyamide-based resin composition was prepared by adding 3 parts by mass of carbon black as a colorant to 100 parts by mass of Evonik Polyamide 1010 DS16 (d=1.05, melting point 200°C, amide group ratio=9, bio-based carbon content 100% by mass), a polyamide-based resin derived from castor oil, using a twin-screw extruder with a screw diameter of 30 mm, and melt-kneading the mixture at 240°C to obtain a resin composition. Next, the POF wire obtained as described above was coated with the resin composition at 220°C using a single-screw extruder with a screw diameter of 40 mmφ and a crosshead die, to a thickness of 0.25 mm, thereby obtaining a POF cable. The resulting POF cable had a diameter of 1.5 mm. The biomass plastic content of the produced POF cable was calculated to be 46 mass %.

[0085] Example 3 The core resin of the POF wire was the same as that in Example 1. The cladding layer constituting the POF strand had a two-layer structure, and the resin for the first cladding layer was a fluoromethacrylate resin obtained by cast polymerization of 20% by mass of tetrafluoropropyl methacrylate (4FM), 60% by mass of pentafluoropropyl methacrylate (5FM), and 20% by mass of methyl methacrylate. The refractive index of the fluoromethacrylate resin was 1.42. As the resin for the second clad layer provided on the outside of the first clad layer, a copolymer (refractive index 1.402) of 72 mass % vinylidene fluoride and 28 mass % tetrafluoroethylene was used. These resins were melted and fed to a spinning head at 220° C., and melt-spun into composite fibers using a concentric composite nozzle. Using the POF wire obtained as described above, a 1.5 mm POF cable was obtained in the same manner as in Example 2. The biomass plastic content of the produced POF cable was calculated to be 46 mass %.

[0086] Example 4 The resin (cladding resin) constituting the first cladding layer was a modified fluorocopolymer (refractive index 1.383) obtained by introducing carbonate groups into a fluorocopolymer having an ethylene-tetrafluoroethylene copolymer as the main skeleton, and the resin constituting the second cladding layer was a copolymer of ethylene, tetrafluoroethylene, and hexafluoropropene (refractive index 1.362). Other conditions were the same as in Example 3, and a 1.0 mm diameter POF was produced. Next, a POF cable having an outer diameter of 1.5 mm was obtained in the same manner as in Example 2 using the POF wire obtained as described above. The biomass plastic content of the produced POF cable was calculated to be 46 mass %.

[0087] Example 5 The resin constituting the cladding layer (cladding resin) was a quaternary copolymer (refractive index 1.36) of perfluoroalkyl vinyl ether, vinylidene fluoride, tetrafluoroethylene, and hexafluoropropene, and the resin constituting the protective layer (protective resin) was a copolymer (refractive index 1.40) of 72% by mass of vinylidene fluoride and 28% by mass of tetrafluoroethylene. These polymers were melted and, under the same conditions as in Example 3, a 1.0 mm diameter POF was fabricated. Next, a POF cable having an outer diameter of 1.5 mm was obtained in the same manner as in Example 2 using the POF wire obtained as described above. The biomass plastic content of the produced POF cable was calculated to be 46 mass %.

[0088] Comparative Example 1 A commercially available petrochemically-derived polyamide 12 resin (d = 1.02, melting point 179°C, amide group ratio = 11, bio-based carbon content 0 mass%) was used, and polyamide 12 and coloring carbon black were melt-kneaded in the same manner as in Example 1, except for the other conditions, to obtain a resin composition. This resin composition was used to coat a POF wire produced in the same manner as in Example 1, to prepare a POF cable. The biomass plastic content of the produced POF cable was calculated to be 0% by mass.

[0089] Comparative Example 2 The resin composition for the coating layer of the POF cable was the same polyamide 12 resin composition as in Comparative Example 1. The other conditions were the same as in Example 3, and the POF cable was produced. The biomass plastic content of the produced POF cable was calculated to be 0% by mass.

[0090] The structure and characteristics of the POF cable produced as described above were measured and evaluated, and the results are shown in Table 1 below.

[0091] [Table 1]

[0092] From the above results, it was found that Example 1, in which a POF bare wire was coated with polyamide 1010, and Example 2, in which a POF bare wire was coated with a polyamide-based resin derived from plant materials, had transmission loss equivalent to that of Comparative Examples 1 and 2, in which a POF bare wire was coated with polyamide 12, and were also excellent in long-term thermal stability, tensile break strength, and repeated bending strength. In particular, with regard to long-term heat resistance, polyamide 1010 (amide group ratio = 9) had a higher amide group concentration than polyamide 12 (amide group ratio = 11), and therefore had excellent oxygen barrier properties and was able to suppress thermal oxidative degradation of the POF cable in a high-temperature environment.

[0093] Example 6 Polymethyl methacrylate (refractive index 1.492) was used as the material for the core, and a copolymer of 72% by mass of vinylidene fluoride and 28% by mass of tetrafluoroethylene (refractive index 1.40) was used as the resin (clad resin) for the clad layer. These materials were placed in the core resin distribution chamber and clad resin distribution chamber of a 217-core composite spinning die, respectively, and a 217-core POF strand with a diameter of 1.0 mm was produced by composite spinning. A POF cable was obtained in the same manner as in Example 1, except that the resin composition for forming the covering layer was changed from commercially available polyamide 1010 to commercially available polyamide 610 (d=1.08, melting point 225°C, amide group ratio=7, bio-based carbon content 0% by mass). However, the outer diameter of the POF cable was set to 2.2 mm. The biomass plastic content of the produced POF cable was calculated to be approximately 0% by mass. The various characteristics of the POF cable were evaluated, and the results are shown in Table 2.

[0094] Example 7 A POF cable was obtained in the same manner as in Example 1, except that the 217-core POF strand having a diameter of 1.0 mm produced in Example 6 was used and the resin composition for forming the coating layer was changed from commercially available polyamide 1010 to polyamide 610 HS16 (d=1.06, melting point 223°C, amide group ratio=7, bio-based carbon content 63% by mass) manufactured by Evonik, which is a polyamide resin derived from castor oil. However, the outer diameter of the POF cable was set to 2.2 mm. The biomass plastic content of the manufactured POF cable was calculated to be approximately 29 mass %. The various characteristics of the POF cable were evaluated, and the results are shown in Table 2.

[0095] Example 8 Using an extruder with a screw diameter of 40 mm, a polyethylene resin composition was prepared by adding 3% by mass of carbon black as a colorant to Arkema's castor oil-derived polyamide 11 BESN P20TL (d = 1.04, melting point 185°C, amide group ratio = 10, bio-based carbon content 99.9%), and melt-kneading it at 200°C to obtain a resin composition. The POF wire produced in Example 6 was coated with the resin composition in a crosshead die to form a coating layer having a thickness of 0.15 mm, thereby producing a POF cable having a diameter of 1.30 mm. The biomass plastic content of the obtained POF cable was calculated to be approximately 32% by mass. Various properties of the POF cable were evaluated, and the results are shown in Table 2.

[0096] Example 9 The core material was polymethyl methacrylate (refractive index 1.491), and the clad layer resin (clad resin) was a copolymer of 72% by mass of vinylidene fluoride and 28% by mass of tetrafluoroethylene (refractive index 1.402). They were placed in the core resin distribution chamber and clad resin distribution chamber of a 217-core conjugate spinning die, respectively, and a 217-core POF strand with a diameter of 0.5 mm was produced by conjugate spinning. Next, in the same manner as in Example 2 described above, a POF cable having a thickness of 0.25 mm and a diameter of 1.0 mm was produced. The biomass plastic content of the obtained POF cable was calculated to be about 68% by mass. The various characteristics of the POF cable were evaluated, and the results are shown in Table 2.

[0097] Comparative Example 3 A POF cable was obtained using the 217-core POF wire with a diameter of 0.5 mm produced in Example 9 and the commercially available petrochemically derived polyamide 12 resin (d=1.02, melting point 179°C, amide group ratio=11, bio-based carbon content 0% by mass) used in Comparative Example 1 as the resin composition for forming the coating layer, in the same manner as in Example 1 except that the outer diameter of the POF cable was 1.0 mm. The biomass plastic content of the produced POF cable was calculated to be approximately 0% by mass. The various characteristics of the POF cable were evaluated, and the results are shown in Table 2.

[0098] [Table 2] [Industrial Applicability]

[0099] The plastic optical fiber cable of the present invention has industrial applicability as a POF cable that conserves petroleum resources and reduces the total amount of carbon dioxide emissions, thereby reducing the environmental impact. [Explanation of symbols]

[0100] 10, 20, 30, 40, 50, 60... Plastic optical fiber cable 12, 22, 32, 42, 52, 62a, 62b... Core 14, 24, 34, 44, 54, 64a, 64b... Cladding layer 441 First cladding layer 442...Second cladding layer 16, 26, 36, 46, 56, 66a, 66b... Plastic optical fiber 18, 29, 38, 48, 59, 68, 68b...Covering layer 28, 58... protective layer

Claims

1. an optical fiber having a core containing a polymer having a methyl methacrylate unit and one or more cladding layers provided on the outer circumferential surface of the core; a coating layer that coats an outer periphery of the optical fiber; , and the coating layer contains a polyamide-based resin (A), The polyamide resin (A) is an aliphatic polyamide resin having an amide group ratio (N1 / N2), which is the ratio of the number of methylene carbon atoms (N1) in the skeleton to the number of amide group carbon atoms (N2), of 7 to 10. Plastic fiber optic cable.

2. The polyamide resin (A) At least one selected from the group consisting of polyamide 610, polyamide 612, polyamide 810, polyamide 812, polyamide 1010, polyamide 1012, and polyamide 11, 2. The plastic optical fiber cable according to claim 1.

3. The polyamide resin (A) is Density is 1.00 g / cm 3 1.40g / cm or more 3 is as follows: The melting point is 180°C or higher and 230°C or lower.

3. The plastic optical fiber cable according to claim 1 or 2.

4. The polyamide resin (A) is It is a polyamide resin derived from plant materials.

4. The plastic optical fiber cable according to claim 1.

5. The polyamide resin (A) is the polyamide-based resin (A) has a bio-based carbon content, which is the proportion of the carbon mass of biomass-derived components calculated from a radiocarbon (14C) measurement value to the total carbon mass constituting the polyamide-based resin (A), of 80 mass% or more; 5. The plastic optical fiber cable according to claim 1.

6. The mass of the total resin constituting the plastic optical fiber cable is The biomass plastic content, which is the proportion of the mass of components derived from plant raw materials, is 25% by mass or more.

6. The plastic optical fiber cable according to claim 1.

7. the cladding layer is made of a fluorine-based resin having a refractive index lower than that of the core; 7. The plastic optical fiber cable according to claim 1.

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