Plastic optical fibers, medical lighting equipment, medical sensor equipment, medical phototherapy equipment, and plastic optical fiber cords

Abstract

Provided is a plastic optical fiber that has a multilayer structure having a core, a first clad, and a second clad, and is characterized in that the core comprises an organic polymeric material having a water absorption of 0.001% or more but less than 0.29% and a total light transmittance of 80% or more, and containing 0.01-10 wt% plasticizer, the relation between the refractive index (X) of the core and the refractive index (Y) of the first clad is X-Y > 0.01, and the relation between the refractive index (Y) of the first clad and the refractive index (Z) of the second clad is Y-Z > 0.05.　The present invention provides the plastic optical fiber having excellent moisture resistance and flex resistance.

Description

[Technical Field]

[0001] The present invention relates to a plastic optical fiber, a medical lighting device, a medical sensor device, a medical phototherapy device, and a plastic optical fiber cord that use the same. [Background technology]

[0002] Plastic optical fibers are superior to glass optical fibers in terms of processability, handling, and manufacturing costs, and are therefore used for short-distance optical signal transmission, light guides, and the like.

[0003] Plastic optical fibers are typically composed of two layers: a core and a cladding. The core is typically made of a polymer with excellent transparency and weather resistance, such as polymethyl methacrylate (PMMA). The cladding, on the other hand, must have a lower refractive index than the core in order to confine light within the core, and fluorine-containing polymers are widely used. However, because PMMA is highly hygroscopic, plastic optical fibers using PMMA for the core have the problem of reduced light transmittance in the visible long-wavelength region around 800 nm due to moisture absorption.

[0004] As a plastic optical fiber with a reduced hygroscopic core, an optical fiber has been proposed in which the core is made of a fluorine-substituted deuterated styrene / deuterated (meth)acrylate copolymer, among other plastic optical fibers having a core and sheath made of synthetic polymers (see, for example, Patent Document 1). However, because polystyrene is brittle and has low elongation, plastic optical fibers using polystyrene for the core have the problem of insufficient bending resistance.

[0005] Therefore, as a plastic optical fiber with excellent bending resistance, an all-plastic optical fiber with a core-sheath-protective layer structure has been proposed, characterized in that the protective material is made of a polymer with a breaking elongation of 30% or more (see, for example, Patent Document 2).

[0006] In particular, plastic optical fibers used in medical applications for endoscopic illumination must be flexible and durable against repeated bending in order to pass through complex internal organs. Light-guiding sensors for robots and photoelectric sensors for industrial equipment also require excellent flexibility because the bending drive section is large. Furthermore, moisture resistance is also required in environments where the plastic optical fiber comes into contact with water, such as inside the body or outdoors. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 61-223806 [Patent Document 2] Japanese Patent Application Publication No. 4-66907 Summary of the Invention [Problem to be solved by the invention]

[0008] Even if the technology described in Patent Document 2 is applied to a plastic optical fiber using polystyrene as a core, there is still a problem that it is insufficient to meet the high bending resistance that has been required in recent years.

[0009] A primary object of the present invention is to provide a plastic optical fiber having excellent moisture resistance and bending resistance. [Means for solving the problem]

[0010] In order to solve the above problems, the plastic optical fiber of the present invention has the following configuration: A plastic optical fiber having a multilayer structure with a core, a first clad and a second clad, wherein the core has a water absorption rate of 0.04 % or more 0.06 % or less, total light transmittance 90 %、 Plasticizer 1 The organic polymer material contains 5 wt% or more and 5 wt% or less, and the relationship between the refractive index (X) of the core and the refractive index (Y) of the first cladding isXY=0.10 The relationship between the refractive index (Y) of the first cladding and the refractive index (Z) of the second cladding is 0.11≧YZ≧0.07, and the following formulas (1) and (2) are satisfied, and the water absorption rate of the second cladding is 0.02 % or more 0.04 % or less, and the modulus of elasticity of the second cladding is 200 MPa or more 1,250 MPa or less. 2≦x≦18 Formula (1) where x: first cladding thickness × 100 / fiber diameter [%] 5≦y≦13 Equation (2) where y: second cladding thickness × 100 / fiber diameter [%]

[0011] The medical lighting device of the present invention has the following configuration: A medical lighting device having the plastic optical fiber.

[0012] The medical sensor device of the present invention has the following configuration: A medical sensor device having the plastic optical fiber.

[0013] The medical phototherapy device of the present invention has the following configuration: A medical phototherapy device having the plastic optical fiber.

[0014] The plastic optical fiber cord of the present invention has the following configuration: The plastic optical fiber cord has at least one coating layer on the outer layer of the plastic optical fiber.

[0015] The plastic optical fiber of the present invention satisfies the following formulas (1) and (2): vinegar.

[0016] 2≦x≦18 Formula (1) where x: first cladding thickness × 100 / fiber diameter [%] 5≦y≦13 Formula (2) Here, y: Second cladding thickness × 100 / fiber diameter [%].

[0017] The plastic optical fiber of the present invention preferably has a polymer in which the core is mainly composed of any one of styrene, cycloolefin, methylpentene, and carbonate.

[0018] The plastic optical fiber of the present invention has a polymer in which the first cladding is made of methyl methacrylate ,Ma or a copolymer containing 0.1% to 12% by weight of at least one copolymer component selected from the group consisting of methyl acrylate, ethyl acrylate, and butyl acrylate, with methyl methacrylate as the main component.

[0019] The plastic optical fiber of the present invention has a water absorption rate of the second cladding 0.02 % or more 0.04 % or less, and an elastic modulus of the second cladding 200 MPa or more 1,250 MPa or less.

[0020] The plastic optical fiber of the present invention preferably contains carbon black in the second cladding to 0.4 wt% or more 4.0 wt% or less.

[0021] The plastic optical fiber of the present invention preferably satisfies R < I, where R (dB / km) is the light transmittance loss at a wavelength of 660 nm and I (dB / km) is the light transmittance loss at a wavelength of 800 nm.

[0022] The plastic optical fiber of the present invention preferably satisfies 0.2 < R / I < 1, where R (dB / km) is the light transmittance loss at a wavelength of 660 nm and I (dB / km) is the light transmittance loss at a wavelength of 800 nm.

[0023] In the plastic optical fiber of the present invention, the melt flow rate of the core (230° C., load 3.8 kg) is preferably 1 g / 10 min or more and 200 g / 10 min or less.

[0024] The plastic optical fiber of the present invention preferably has a fiber diameter of 100 μm or more and 500 μm or less. [Effects of the Invention]

[0025] According to the present invention, a plastic optical fiber having excellent moisture resistance and bending resistance can be provided. DETAILED DESCRIPTION OF THE INVENTION

[0026] Below, we will specifically explain preferred embodiments of the plastic optical fiber and the plastic optical fiber cord containing the same according to the present invention, but the present invention is not limited to the following embodiments and can be implemented with various modifications depending on the purpose and application.

[0027] The plastic optical fiber of the present invention has a core, a first cladding, and a second cladding in this order. It may have three or more cladding layers, in which case the innermost cladding in contact with the core is called the first cladding, and the cladding located outside the first cladding and in contact with the first cladding is called the second cladding.

[0028] (core) In the plastic optical fiber of the present invention, the core is preferably a polymer primarily composed of styrene, cycloolefin, methylpentene, or carbonate, and more preferably a polymer primarily composed of styrene residues. Using these preferred polymers for the core stabilizes transmittance. Examples of polymerization components (monomers) for such polymers include styrene; substituted styrenes such as methylstyrene and α-methylstyrene; (meth)acrylic acid esters; (meth)acrylic acid; and N-substituted maleimides. (Meth)acrylic acid esters are a general term for acrylic acid and methacrylic acid, and examples include methyl acrylate, ethyl methacrylate, butyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, phenyl methacrylate, bornyl methacrylate, and adamantyl methacrylate. Examples of N-substituted maleimides include N-isopropylmaleimide, N-cyclohexylmaleimide, N-methylmaleimide, N-ethylmaleimide, and N-methylphenylmaleimide. Two or more of these may be used. In the present invention, a polymer containing styrene residues as a main component refers to a polymer in which 50 mol % or more of the repeating units constituting the polymer are derived from styrene. The repeating units constituting the polymer preferably contain 70 mol % or more, more preferably 90 mol % or more, of styrene residues. By selecting a polymer containing styrene residues as a main component, moisture resistance can be improved.

[0029] In the plastic optical fiber of the present invention, the core contains a plasticizer. 1 wt% or more 5 The content of the plasticizer in the core is 0.01 wt% or less. By including the plasticizer, the moldability and flexibility of the core can be improved, and the flex resistance can be further improved. The content of the plasticizer in the core is 1 If the content of the plasticizer in the core is less than 10 wt%, the core will have poor moldability and flexibility. 5 If it is greater than wt%, heat resistance will deteriorate. 。

[0030] The plasticizer for the core is a compound that imparts flexibility, weather resistance, and processability to the resin. Examples of plasticizers include, but are not limited to, epoxy plasticizers, phthalate ester plasticizers, polyester plasticizers, and hydrocarbons such as paraffin and polyethylene oxide.

[0031] Specific examples include, but are not limited to, epoxidized soybean oil (ESBO), epoxidized linseed oil (ELSO), dioctyl adipate (DOA), diisononyl adipate (DINA), tricresyl phosphate (TCP), acetyl tributyl citrate (ATBC), trioctyl trimellitate (TOTM), sebacate esters, azelaate esters, solid paraffin, light liquid paraffin, heavy liquid paraffin, bis(2-ethylhexyl) phthalate (DEHP), butyl benzyl phthalate (BBP), dibutyl phthalate (DBP), diisobutyl phthalate, diisodecyl phthalate (DIDP), dioctyl phthalate (DOP), polyethylene oxide (PEO), and polyethylene glycol (PEG).

[0032] The core may contain stabilizers such as antioxidants and heat stabilizers to the extent that they do not affect light transmittance.

[0033] The water absorption rate of the core is 0.04 % or more 0.06 % or less. 0.06 If it is greater than %, it will easily absorb moisture and its permeability will change over time. 。

[0034] The total light transmittance of the core is 80% or more. If the total light transmittance is less than 80%, the transmittance is poor and light does not pass through even if the fiber is short, making it unsuitable for sensor applications. The total light transmittance is preferably 85% or more, and more preferably 87% or more.

[0035] The relationship between the refractive index of the core (X) and the refractive index of the first cladding (Y) is XY =0.1 XY ≠0.1 If this occurs, it will be impossible to confine light in the core.

[0036] The melt flow rate of the core (230°C, 3.8 kg load) is preferably 1 g / 10 min or more and 200 g / 10 min or less. This range ensures stable spinning, the process of forming the core. A more preferred melt flow rate (230°C, 3.8 kg load) is 1 g / 10 min or more and 100 g / min or less.

[0037] (Clad) The plastic optical fiber of the present invention has at least two cladding layers.

[0038] In the plastic optical fiber of the present invention, the first cladding is a polymer made of methyl methacrylate. ,Ma Alternatively, it is preferably a copolymer containing methyl methacrylate as the main component and 0.1% by weight to 12% by weight of at least one copolymerization component selected from the group consisting of methyl acrylate, ethyl acrylate, and butyl acrylate. In the present invention, a polymer containing methyl methacrylate as the main component refers to a polymer in which 50 mol % or more of the repeating units constituting the polymer are derived from methyl methacrylate. The first clad material preferably has a lower refractive index than the core and excellent interfacial adhesion with the core. By selecting a polymer made of methyl methacrylate and / or the above-mentioned copolymer containing methyl methacrylate as the main component for the first clad, it is possible to improve both the interfacial adhesion with the core and flex resistance.

[0039] Examples of copolymerization components of the copolymer containing methyl methacrylate as the main component include (meth)acrylic acid esters, (meth)acrylic acid, styrene, substituted styrenes, and N-substituted maleimides. Examples of (meth)acrylic acid esters, substituted styrenes, and N-substituted maleimides include those exemplified as polymerization components of the core. Two or more of these may be used.

[0040] Preferably, the copolymer contains methyl methacrylate as the main component and 0.1% by weight to 12% by weight of at least one copolymer component selected from the group consisting of methyl acrylate, ethyl acrylate, and butyl acrylate. By blending methyl acrylate, ethyl acrylate, or butyl acrylate as a copolymer component, heat resistance can be imparted and the melt viscosity can be adjusted. Methyl acrylate is preferred. In this case, the interfacial adhesion with the core can be further improved, and the breaking strength of the plastic optical fiber can be increased. The copolymer component content is more preferably 0.3% by weight to 10% by weight. It is even more preferably 0.8% by weight to 6% by weight.

[0041] The plastic optical fiber of the present invention satisfies the following formula (1): vinegar. 2 ≦x≦ 18 Formula (1) Here, x represents the percentage of the thickness of the first cladding relative to the fiber diameter, and is expressed as x = first cladding thickness × 100 / fiber diameter [%]. 2 %, the interfacial adhesion between the core and the first clad and between the first clad and the second clad is improved, and the flex resistance is improved. 3 % or more, and more preferably 4 % or more. On the other hand, if x is 18 % or less, the proportion of the second clad, which has relatively excellent flex resistance, increases, thereby improving flex resistance. to Preferably, it is 8% or less.

[0042] Here, the thickness of the first cladding and the fiber diameter can be measured by cutting five randomly selected locations of a plastic optical fiber perpendicular to the drawing direction, polishing the cross section so that the core / first cladding / second cladding interface can be observed, and then observing the cross section under magnification using a VHX-7000 digital microscope (manufactured by Keyence Corporation). The magnification for magnification observation is between 10 and 200 times, and a range is selected in which the entire cross section fits within the field of view and the interface can be observed. The thickness of the thinnest part of the first cladding on the cross section is measured and taken as the thickness of the first cladding. The diameter of the optical fiber is measured as the fiber diameter. If the cross section shape is not circular, the shortest diameter of the optical fiber is taken as the fiber diameter. The fiber diameter and the thickness of the first cladding are measured for each of the five cross sections, and the average values ​​are taken as the fiber diameter and the thickness of the first cladding.

[0043] In the plastic optical fiber of the present invention, the relationship between the refractive index (Y) of the first cladding and the refractive index (Z) of the second cladding is YZ>0.05. If YZ≦0.05, light tends to leak from the second cladding.

[0044] In the plastic optical fiber of the present invention, the water absorption rate of the second cladding is 0.02 % or more 0.04 % or less. Within this range, moisture absorption can be suppressed. . The modulus of elasticity of the 2nd cladding is 200 MPa or more 1,250 MPa or less. 200 MPa or more, the second clad provides a good protection effect for the first clad, and the bending resistance is improved. 1,250 MPa or less, the stress on the first cladding during bending is alleviated, improving bending resistance. .The flexural modulus is measured according to ASTM D790 (2010). A test piece measuring 127mm x 13mm x 3.1mm is used, and the measurement unit is kg / cm2. The flexural modulus is determined from the tangent to the steepest initial slope of the bending load-deflection curve. If it is difficult to sample the clad and measure the flexural modulus directly, and the composition of the clad is known, it is possible to prepare a clad of the same composition and measure the flexural modulus.

[0045] One way to adjust the flexural modulus of the second cladding to this range is to use a fluorine-containing polymer, which will be described later.

[0046] In the plastic optical fiber of the present invention, the second cladding preferably contains a fluorine-containing polymer. Examples of polymerization components of the fluorine-containing polymer include vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, hexafluoroacetone, perfluoroalkyl methacrylate, hexafluoropropyl methacrylate, tetrafluoropropyl methacrylate, and pentafluoropropyl methacrylate. Two or more of these may be used. The fluorine content of the second cladding is preferably 50% by weight or more. By making the fluorine content 50% by weight or more, the proportion of monomer residues with low fluorine content, such as acrylate and methacrylate, is reduced, making it possible to easily adjust the flexural modulus of the second cladding to the aforementioned preferred range and further improving bending resistance.

[0047] It is preferable to use ethylene as a polymerization component of the fluorine-containing polymer of the second cladding. Copolymerization of ethylene improves moldability and increases the breaking strength of the plastic optical fiber.

[0048] The second clad is carbon black to 0.4 wt% or more 4.0 It is preferable that the content is 5 wt % or more. 0.4If the content is more than wt%, external light can be blocked and the sensor sensitivity becomes stable. . 4.0wt% or less In this case, the workability of the second clad is improved. It is more preferably less than 3.0 wt%, and even more preferably 1.0 wt% or more.

[0049] The second clad may contain pigments such as titanium dioxide, zinc oxide, and chromium oxide, as well as other additives, in addition to carbon black, as long as the properties of the second clad are not impaired.

[0050] The copolymer of the second clad preferably has a carbonyl group-containing functional group at the polymer chain end or in a side chain, which can improve solvent resistance.

[0051] Examples of carbonyl group-containing functional groups include carbonate groups having an -OC(=O)O- bond and carboxylic acid halide groups having a structure of -COY (Y is a halogen element). It is more preferable that these groups contain fluorine, and fluorine-containing carbonate groups (-RF-OC(=O)-RF'-) and carboxylic acid fluoride groups (-C(=O)F) are preferred. Here, RF and RF' represent groups containing fluorine, such as alkyl fluoride groups and vinylidene fluoride groups.

[0052] The plastic optical fiber of the present invention satisfies the following formula (2): vinegar.

[0053] 5≦y ≦13 Formula (2) Here, y represents the percentage of the second cladding thickness relative to the fiber diameter, and is expressed as y = second cladding thickness × 100 / fiber diameter [%]. When y is in the above range, the proportion of the second cladding in the plastic optical fiber can be secured, thereby preventing a decrease in bending resistance. Preferably, it is 7% or more.

[0054] Here, the thickness of the second cladding and the fiber diameter are measured in the same manner as the thickness of the first cladding and the fiber diameter described above.

[0055] For the plastic optical fiber of the present invention, it is preferable that the light transmission loss R (dB / km) at a wavelength of 660 nm and the light transmission loss I (dB / km) at a wavelength of 800 nm satisfy R < I. More preferably, 0.2 < R / I < 1. Generally, wavelengths of 660 nm and 800 nm are wavelengths that easily pass through a living body, and thus are used as indices for sensor sensitivity. In particular, for the wavelength of 660 nm, the reflectance greatly changes depending on the oxygen content of hemoglobin, while for the wavelength of 800 nm, the index of R / I, which is the value obtained by dividing R by I, utilizing the property of being hardly affected by the oxygen content, is often used as the sensor sensitivity. When it is greater than 0.2, the permeability at the wavelength of 660 nm is good, so the sensor sensitivity is improved. Also, when it is less than 1, the permeability at 800 nm is good, so the sensor sensitivity is stabilized.

[0056] The fiber diameter of the plastic optical fiber of the present invention is preferably 100 μm or more and 500 μm or less. By setting the fiber diameter to 100 μm or more, the amount of light required for irradiation can be ensured. On the other hand, by setting the fiber diameter to 500 μm or less, the bending resistance can be further improved.

[0057] As a method for manufacturing a plastic optical fiber, for example, a composite spinning method in which a core material and a cladding material are discharged from a concentric composite die in a heat-melted state to form a three-layer core-sheath structure of core / 1st cladding / 2nd cladding is preferably used. Subsequently, for the purpose of improving mechanical properties such as the breaking strength, a stretching treatment of about 1.2 to 3 times is generally performed to obtain a plastic optical fiber.

[0058] The temperature during spinning should be lower, preferably 250°C or lower, and more preferably 240°C or lower.

[0059] The plastic optical fiber cord according to an embodiment of the present invention has at least one coating layer on the outer layer of the aforementioned plastic optical fiber. Examples of materials for forming the coating layer include polyethylene, polypropylene, copolymers or blends thereof, olefin-based polymers containing organosilane groups, ethylene-vinyl acetate, polyvinyl chloride, polyvinylidene fluoride, polyamide resins such as nylon 12, polyester resins, nylon elastomers, polyester elastomers, urethane resins, fluorine resins, and rubbers such as EPM and EPDM. The coating layer may be single-layered or multi-layered. In the case of multi-layered coatings, a tension member such as "Kevlar" (registered trademark) may be inserted between the coating layers. These coating layers may contain stabilizers such as flame retardants, antioxidants, anti-aging agents, and UV stabilizers. The coating layer can be formed by known methods such as melt extrusion molding using a crosshead die.

[0060] An endoscopic illumination device according to an embodiment of the present invention has the above-described plastic optical fiber and can be used in combination with an endoscope. An ophthalmic surgical illumination probe according to an embodiment of the present invention has the above-described plastic optical fiber as an illumination for ophthalmic surgery. A vascular catheter according to an embodiment of the present invention has the above-described plastic optical fiber as an illumination for the catheter or an optical sensor. [Example]

[0061] The present invention will be described in more detail below with reference to examples. Evaluations in each example and comparative example were carried out by the following methods.

[0062] Core water absorption rate: The supplier's published value was used. If the supplier's published value was unknown, a sample was prepared based on the information obtained from an analysis of the core composition in accordance with JIS K 7209, and the water absorption rate was calculated.

[0063] Core composition ratio: For the core materials used in each of the examples and comparative examples, the amount of styrene residue in the polymer was determined using GC / MS (GC: 7890A, manufactured by Agilent; MS: JMS-Q1050GC, manufactured by JEOL).

[0064] Clad composition ratio: The clad materials used in each example and comparative example were 19 The composition ratio (wt %) was determined using F-NMR (AVANCE NEO 400 manufactured by Bruker) and FT-IR (FT-IR manufactured by Bio-Rad Digilab).

[0065] Flexural modulus of cladding: Measured according to ASTM D790 (2010).

[0066] A test piece of 127 mm x 13 mm x 3.1 mm was prepared from the second clad material used in each example and comparative example, and the measurement unit was kg / cm 2 The flexural modulus was calculated from the tangent to the steepest initial slope of the bending load-deflection curve.

[0067] Light loss of plastic optical fiber when immersed in water (moisture resistance): The light intensity was measured using an 820 nm LED (light-emitting diode) for the plastic optical fiber obtained in each example and comparative example. In addition, the plastic optical fiber obtained in each example and comparative example was immersed 10 m in water at 23°C, and the light intensity was measured in the same way 100 hours later. The decrease (light loss) obtained by subtracting the initial light intensity from the light intensity when immersed in water was used as an index of moisture resistance. A negative light loss value means that the light intensity when bent was lower than the initial light intensity. The smaller the absolute value of the light loss, the better the moisture resistance.

[0068] Number of bending times (durability) of plastic optical fiber until breakage: A load of 175 g was applied to one end of the plastic optical fiber obtained in each example and comparative example, and it was supported by a mandrel with a diameter of 10 mm. The other end of the fiber was bent continuously at an angle of 180° around the support point, and the number of bending times until the plastic optical fiber broke was measured (average value of n=5). The higher the number of bending times, the better the durability.

[0069] Light loss (bending resistance) of plastic optical fiber in a bent state: The light intensity of the plastic optical fiber obtained in each example and comparative example was measured using an 820 nm LED (light-emitting diode). In addition, the plastic optical fiber obtained in each example and comparative example was wrapped 360 degrees around a metal rod with a radius of 5 mm, and the light intensity was measured in the same way. The reduction (light loss) obtained by subtracting the initial light intensity from the light intensity in a bent state was used as an index of bending resistance. A negative light loss value means that the light intensity in a bent state was lower than the initial light intensity. The smaller the absolute value of the light loss, the better the bending resistance.

[0070] Breaking strength of plastic optical fiber: For the plastic optical fibers obtained in each example and comparative example, a tensile test was conducted in accordance with JIS C 6837 (2015) at a pulling speed of 100 mm / min to measure the strength (breaking strength) when the plastic optical fiber broke. Measurements were conducted for three samples each, and the average value was used.

[0071] Light transmission loss of plastic optical fiber: For the plastic optical fibers obtained in each example and comparative example, wavelengths of 660 nm and 800 nm were selected from a halogen lamp light source, and the light transmission loss (dB / km) was measured with a 5 m-2 m cutback. [Example 1] A methyl methacrylate / methyl acrylate copolymer having the composition ratio shown in Table 1 was supplied to the composite spinning machine as the first cladding material, and a vinylidene fluoride polymer was supplied to the composite spinning machine as the second cladding material. Furthermore, 95% by weight of polystyrene with a styrene residue content of 100 mol% produced by continuous continuous polymerization and 5% by weight of liquid paraffin were supplied to the composite spinning machine as the core material, and the core and cladding were subjected to core-sheath composite melt spinning at 220°C to obtain a plastic optical fiber with a fiber diameter of 300 μm (core diameter 228 μm, first cladding thickness 6 μm, second cladding thickness 30 μm).

[0072] The plastic optical fiber thus obtained was evaluated by the above-mentioned evaluation method, and the results are shown in Table 2. [Example 2] A plastic optical fiber was obtained in the same manner as in Example 1, except that the cladding material of the first cladding was changed to a polymer having the composition shown in Table 1. The obtained plastic optical fiber was evaluated in the same manner as in Example 1, and the results are shown in Table 2. [Example 3] A plastic optical fiber was obtained in the same manner as in Example 1, except that the cladding thickness of the second cladding was changed so that y had the value shown in Table 1. The obtained plastic optical fiber was evaluated in the same manner as in Example 1, and the results are shown in Table 2. [Example 4] A plastic optical fiber was obtained in the same manner as in Example 1, except that the cladding material of the second cladding was changed to a copolymer having the composition ratio shown in Table 1. The obtained plastic optical fiber was evaluated in the same manner as in Example 1, and the results are shown in Table 2. [Example 5] A plastic optical fiber was obtained in the same manner as in Example 1, except that the ratio of polystyrene to liquid paraffin in the core material was changed to the value in Table 1. The obtained plastic optical fiber was evaluated in the same manner as in Example 1, and the results are shown in Table 2. [Example 6] A plastic optical fiber was obtained in the same manner as in Example 1, except that the cladding material of the second cladding was changed to a copolymer having the composition ratio shown in Table 1. The obtained plastic optical fiber was evaluated in the same manner as in Example 1, and the results are shown in Table 2. [Examples 7 to 9] A plastic optical fiber was obtained in the same manner as in Example 1, except that the cladding material of the first cladding was changed to a polymer having the composition shown in Table 1. The obtained plastic optical fiber was evaluated in the same manner as in Example 1, and the results are shown in Table 2. [ reference example 1 ] Except for not using liquid paraffin as the core material, a plastic optical fiber was obtained in the same manner as in Example 7. The obtained plastic optical fiber was evaluated in the same manner as in Example 1, and the results are shown in Table 2. [Example 10、11 ] A plastic optical fiber was obtained in the same manner as in Example 1, except that the cladding material of the first cladding was changed to the polymer shown in Table 1. The obtained plastic optical fiber was evaluated in the same manner as in Example 1, and the results are shown in Table 2. [Example 12、13 ] A plastic optical fiber was obtained in the same manner as in Example 1, except that the thicknesses of the first cladding and the second cladding were changed to the values ​​shown in Table 1. The obtained plastic optical fiber was evaluated in the same manner as in Example 1, and the results are shown in Table 2. [Example 14 ~ 16 ] Except for using liquid paraffin or PEO for the core material and carbon black for the second cladding, a plastic optical fiber was obtained in the same manner as in Example 1. The obtained plastic optical fiber was evaluated in the same manner as in Example 1, and the results are shown in Table 2. [ reference example 2 ~ 4 ] A plastic optical fiber was obtained in the same manner as in Example 1, except that the core material was changed as shown in Table 1. The obtained plastic optical fiber was evaluated in the same manner as in Example 1, and the results are shown in Table 2. [ reference example 5 ] A plastic optical fiber was obtained as a core material in the same manner as in Example 10, except that the spinning temperature was 250° C. The obtained plastic optical fiber was evaluated in the same manner as in Example 1, and the results are shown in Table 2. [Comparative Examples 1 to 4] Plastic optical fibers were obtained in the same manner as in Example 1, except that the core material and cladding material were changed to copolymers having the composition ratios shown in Table 3. These plastic optical fibers were evaluated in the same manner as in Example 1, and the results are shown in Table 4. [Comparative Example 5 ] Regarding the cladding thickness, plastic optical fibers were obtained in the same manner as in Example 1, except that x and y were changed to the values ​​shown in Table 3. These plastic optical fibers were evaluated in the same manner as in Example 1, and the results are shown in Table 4. [Comparative Example 6 ~ 7 ] Except for changing the cladding to a single-layer structure, plastic optical fibers were obtained in the same manner as in Example 1. The same evaluations as in Example 1 were carried out on these plastic optical fibers, and the results are shown in Table 4. [Comparative Example 8 ] A plastic optical fiber was obtained in the same manner as in Example 1, except that the core and cladding were changed to copolymers having the composition ratios shown in Table 3. The obtained plastic optical fiber was evaluated in the same manner as in Example 1, and the results are shown in Table 4.

[0073] [Table 1]

[0074] The meanings of the abbreviations in Table 1 are as follows. The meanings of the abbreviations in Table 3 below are also the same.

[0075] LP: liquid paraffin, St: polystyrene, PEO: polyethylene oxide, TPX: polymethylpentene, PC: polycarbonate, PC: polycarbonate, COP: polycycloolefin, MMA: methyl methacrylate, MA: methyl acrylate, 2F: vinylidene fluoride, 4F: tetrafluoroethylene, 6F: hexafluoropropylene, FVE: heptafluorovinyl ether, 4FM: tetrafluoropropyl methacrylate, 5FM: pentafluoropropyl methacrylate.

[0076] [Table 2]

[0077] [Table 3]

[0078] [Table 4] [Industrial Applicability]

[0079] The plastic optical fiber and plastic optical fiber cord of the present invention can be suitably used for wiring inside moving bodies such as automobiles, aircraft, ships, and trains, wiring for short-distance communication in AV equipment, domestic appliances, office equipment, etc., medical endoscopic lighting, ophthalmic surgical lighting, laparoscopic surgical lighting, catheter lighting, microscope lighting, light-guiding sensors for robots, photoelectric sensors for industrial equipment, automobile collision sensors, decorative wall lighting, interior lighting, etc. In particular, because of their high aperture ratio, moderate flexibility, and properties that make it difficult for transmission loss to decrease even when bent, they are suitable for use in lighting medical equipment and industrial sensors, and more specifically for use in endoscopic lighting, ophthalmic surgical lighting, and catheters.

Claims

1. A plastic optical fiber having a multilayer structure having a core, a first cladding, and a second cladding, wherein the core is made of an organic polymer material having a water absorption rate of 0.04% or more and 0.06% or less, a total light transmittance of 90%, and containing a plasticizer at 1 wt% or more and 5 wt% or less, wherein the relationship between the refractive index (X) of the core and the refractive index (Y) of the first cladding is X-Y=0.10, and the relationship between the refractive index (Y) of the first cladding and the refractive index (Z) of the second cladding is 0.11≧Y-Z≧0.07, and the plastic optical fiber satisfies the following formulas (1) and (2): the water absorption rate of the second cladding is 0.02% or more and 0.04% or less, and the elastic modulus of the second cladding is 200 MPa or more and 1,250 MPa or less. 2≦x≦18 Formula (1) where x: first cladding thickness x 100 / fiber diameter [%] 5≦y≦13 Formula (2) where y: second cladding thickness×100 / fiber diameter [%]

2. 2. The plastic optical fiber according to claim 1, wherein the core is a polymer containing one of styrene, cycloolefin, methylpentene, and carbonate as a main component.

3. A plastic optical fiber as described in claim 1 or 2, characterized in that the first cladding is a polymer consisting of methyl methacrylate or a copolymer having methyl methacrylate as the main component and containing 2 to 10 weight % of at least one copolymer component selected from the group consisting of methyl acrylate, ethyl acrylate, and butyl acrylate.

4. 4. The plastic optical fiber according to claim 1, wherein the second cladding contains carbon black in an amount of 0.4 wt % to 4.0 wt %.

5. 5. The plastic optical fiber according to claim 1, wherein the transmission loss R (dB / km) at a wavelength of 660 nm and the transmission loss I (dB / km) at a wavelength of 800 nm satisfy the relationship R<I.

6. 6. The plastic optical fiber according to claim 1, wherein the transmission loss R (dB / km) at a wavelength of 660 nm and the transmission loss I (dB / km) at a wavelength of 800 nm satisfy the relationship 0.2<R / I<1.

7. 7. The plastic optical fiber according to claim 1, wherein the melt flow rate of the core (at 230° C. and a load of 3.8 kg) is 1 g / 10 min or more and 200 g / 10 min or less.

8. 8. The plastic optical fiber according to claim 1, wherein the fiber diameter is 100 μm or more and 500 μm or less.

9. A medical lighting device comprising the plastic optical fiber according to any one of claims 1 to 8.

10. A medical sensor device comprising the plastic optical fiber according to any one of claims 1 to 8.

11. A medical phototherapy device comprising the plastic optical fiber according to any one of claims 1 to 8.

12. A plastic optical fiber cord having at least one coating layer on the outer layer of the plastic optical fiber according to any one of claims 1 to 8.

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