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EP-3598187-B1 - PLASTIC OPTICAL FIBER, PLASTIC OPTICAL FIBER CABLE, WIRING HARNESS AND VEHICLE

EP3598187B1EP 3598187 B1EP3598187 B1EP 3598187B1EP-3598187-B1

Inventors

  • KIHARA, HIDEKI
  • FUJIKURA, NOBORU

Dates

Publication Date
20260506
Application Date
20180312

Claims (14)

  1. A plastic optical fiber (10) comprising: one core (11); and at least two layers of clads of a first clad (12a) and a second clad (12b) formed in this order concentrically on the outer circumference of the core (11), wherein a transmission band is 100 MHz or wider, as measured under conditions of a wavelength of 650 nm and a launch NA = 0.65; and a transmission loss is 350 dB/km or less, as measured under conditions of a wavelength of 650 nm and a launch NA = 0.1, after exposure to an environment of a temperature of 105°C for 1000 hours, wherein the material for the first clad (12a) comprises a copolymer comprising 0 to 70% by mass of a repeating unit derived from at least one fluoroalkyl (meth)acrylate represented by the following Formula (1) or the following Formula (2), where Formula (1) excludes 2-(perfluorohexyl)ethyl methacrylate, and 7 to 55% by mass of a repeating unit derived from 2-(perfluorohexyl)ethyl methacrylate, based on the total mass of the materials: wherein R is a hydrogen atom or a methyl group, X is a hydrogen atom or a fluorine atom, m is 1 or 2, and n is an integer of 5 to 13; wherein R is a hydrogen atom or a methyl group, X is a hydrogen atom or a fluorine atom, m is 1 or 2, and n is an integer of 1 to 4; wherein the material for the second clad (12b) comprises a fluorine-containing olefin-based polymer comprising a tetrafluoroethylene unit and having a heat of crystal melting of 40 mJ/mg or smaller in differential scanning calorimetry (DSC); and wherein the refractive index of the material for the second clad (12b) is 1.340 to 1.395.
  2. The plastic optical fiber (10) according to claim 1, wherein the transmission band is 150 MHz or wider, as measured under the conditions of the wavelength of 650 nm and the launch NA = 0.2.
  3. The plastic optical fiber (10) according to claim 1 or 2, wherein a difference is 1 dB or smaller between a quantity of light, as measured at a wavelength of 650 nm and overfilled launch in a state in which an optical fiber is linearly held, and a quantity of light, as measured in a state in which the optical fiber is bent at a bending radius of 10 mm and a bending angle of 90°.
  4. The plastic optical fiber (10) according to any one of claims 1 to 3, wherein a number of times of repetitive bending is 14500 or more, as measured by a repetitive bending test according to IEC 60794-1-21: 2015 as specified in the description.
  5. The plastic optical fiber (10) according to any one of claims 1 to 4, wherein a material for the core (11) comprises a homopolymer of methyl methacrylate, or a copolymer of methyl methacrylate and one or more vinyl-based monomers.
  6. The plastic optical fiber (10) according to any one of claims 1 to 5, wherein a refractive index of a material for the first clad (12a) is 1.430 to 1.485.
  7. The plastic optical fiber (10) according to any one of claims 1 to 6, wherein the material for the second clad (12b) comprises a polymer comprising: 25.01 to 92% by mole of a repeating unit derived from vinylidene fluoride; 0.01 to 54% by mole of a repeating unit derived from tetrafluoroethylene; and 3.0 to 20.99% by mole of a repeating unit derived from hexafluoropropylene.
  8. A plastic optical fiber (10) comprising: a core (11) comprising a homopolymer of methyl methacrylate or a copolymer of methyl methacrylate and one or more vinyl-based monomers; and clads of a first clad (12a) and a second clad (12b) formed in this order concentrically on an outer circumferential surface of the core (11), wherein a material for the first clad (12a) comprises a copolymer comprising 0 to 70% by mass of a repeating unit derived from at least one fluoroalkyl (meth)acrylate represented by the following Formula (1) or the following Formula (2), where Formula (1) excludes 2-(perfluorohexyl)ethyl methacrylate, and 7 to 55% by mass of a repeating unit derived from 2-(perfluorohexyl)ethyl methacrylate, based on the total mass of the materials, and a refractive index of the material for the first clad (12a) is 1.430 to 1.485: wherein R is a hydrogen atom or a methyl group, X is a hydrogen atom or a fluorine atom, m is 1 or 2, and n is an integer of 5 to 13; wherein R is a hydrogen atom or a methyl group, X is a hydrogen atom or a fluorine atom, m is 1 or 2, and n is an integer of 1 to 4; and wherein a material for the second clad (12b) comprises a fluorine-containing olefin-based polymer which contains a tetrafluoroethylene unit and has a heat of crystal melting of 40 mJ/mg or smaller in differential scanning calorimetry (DSC), and wherein the material for the second clad (12b) comprises a polymer containing: 25.01 to 92% by mole of a repeating unit derived from vinylidene fluoride; 0.01 to 54% by mole of a repeating unit derived from tetrafluoroethylene; and 3.0 to 20.99% by mole of a repeating unit derived from hexafluoropropylene.
  9. The plastic optical fiber (10) according to claim 8, wherein a refractive index of the material for the second clad (12b) is 1.340 to 1.395.
  10. The plastic optical fiber (10) according to claim 8 or 9, wherein when an outer diameter of the plastic optical fiber (10) is represented by A (µm) and a thickness of the first clad (12a) is represented by a (µm), the diameter and the thickness satisfy the following formulae (i) and (ii): 900 ≤ A ≤ 1100 and 3.0 ≤ a ≤ 35
  11. A plastic optical fiber cable comprising: the optical fiber (10) according to any one of claims 1 to 10; and a covering layer provided on an outer circumference of the optical fiber.
  12. The plastic optical fiber cable according to claim 11, wherein a material for the covering layer comprises a polyamide resin.
  13. A wire harness comprising: the plastic optical fiber cable according to claim 11 or 12 and an electric wire bundled together with the plastic optical fiber cable.
  14. A vehicle comprising at least one selected from the plastic optical fiber cable according to claim 11 or 12, and the wire harness according to claim 13.

Description

Technical Field The present invention relates to a plastic optical fiber, a plastic optical fiber cable, a wire harness and a vehicle. Background Art Optical fibers are used in a wide range of applications, such as communication, sensors, lighting, decoration and displays. Glass-based optical fibers are excellent in light transmission property over a wide wavelength, but have problems to be inferior in workability and mechanical characteristics. On the other hand, examples of plastic optical fibers include a plastic optical fiber having a structure in which an outer circumference of a core that is formed from a resin having a high transparency such as polymethyl methacrylate is covered with a resin having high transparency and a lower refractive index than the core, and have features to be excellent in workability and flexibility, as compared to the glass-based optical fibers. In addition, the plastic optical fibers have recently increased a transmission distance with an improvement of a manufacturing technology, and are expanding the applications such as optical information communication in trains, aircrafts and vehicles such as automobiles, and optical information communication in a field of factory automation (FA). The plastic optical fibers, when being used in the vehicles such as the automobiles or for the optical information communication in the FA field, are usually used in an environment close to a high-temperature body such as an engine or used in a high-temperature environment in summer, and accordingly, it is desired that the plastic optical fibers are excellent in long-term heat resistance so that a transmission loss does not increase even when having been exposed to heat for a long period of time. In recent years, the plastic optical fibers are being combined with a visible red-light source that can be driven at high speed, and are being used as a signal transmission line for a high-speed LAN, and the plastic optical fibers are desired to be excellent in band characteristics. In addition, the plastic optical fibers, when being used as wiring in a vehicle such as an automobile, are usually used in a state of being laid in a state of being bent in a narrow space. In this case, it is desired for the plastic optical fiber that a loss of a quantity of light is small even if the plastic optical fiber has been bent (low bending loss) at a radius of 10 mm, in other words, a flexibility is desired. Furthermore, it is desired for the plastic optical fiber that even when being used in a vehicle such as an automobile, in a state of having received a mechanical action such as vibration, or being used in a factory automation (FA) field while a state in which the fiber is bent and a state in which the fiber is kept linearly are repeated, the plastic optical fiber does not cause a crack in the core or the clad of itself, or delamination between the core and the clad, or delamination between clads in the case of clads formed of two or more layers, and does not increase the transmission loss. In other words, a plastic optical fiber excellent in mechanical durability is desired. As a method for improving a transmission band of the plastic optical fiber, an optical fiber is disclosed in which a material for the clad is optimized, in Patent Literatures 1 and 4, for example. In addition, in Patent Literature 2 (for example, Example 9), an optical fiber is disclosed in which a material for a first clad in clads of a two-layer structure is optimized, as a method of improving heat resistance (glass transition temperature) and the like. As a method of improving the long-term heat resistance and flexibility of the plastic optical fiber, an optical fiber is disclosed in which a material for the second clad is optimized, in Patent Literature 3, for example. JP 2007 052095 A relates to a plastic optical fiber cable including a coated plastic optical fiber having a core composed of a polymer containing methyl methacrylate units and having one or more clad layers formed on the outer periphery of the core; and a coating layer covering the outer circumference of the coated plastic optical fiber, wherein at least the outermost layer of the clad layers is composed of special fluorine-contained olefinic resin, wherein the coating layer is composed of a coating material containing special polybutyleneterephthalate and a light shielding agent. JP 2002 040267 A relates to a plastic optical fiber being manufactured by subjecting a core resin and the sheath resin to multicomponent fiber spinning by a double-layer multicomponent fiber spinning die provided with a nozzle having contracting parts 4, 5 at which a nozzle radius gradually reduces from an upstream part to a downstream part. JP 2014 228815 A relates to a resin composition for covering an optical fiber containing 80-99.5 mass% of a fluorine-based resin and 0.5-20 mass% of an acid acceptor, wherein the acid acceptor contained in the resin composition for covering the optical fib