Plastic Optical Fiber

Abstract

A plastic optical fiber (1) comprises a plastic optical fiber main body (2) and a coloring material (3) covering the peripheral surface thereof. The coloring material (3) is formed by a cured product of a curable composition, the curable composition comprising an active energy ray-curable multifunctional acrylate and a colorant. The reaction rate of the vinyl group in the active energy ray-curable multifunctional acrylate in the coloring material (3) is 85% or more.

Description

Technical Field

[0001] The present invention relates to plastic optical fibers. Background Art

[0002] Conventionally, there is known an optical fiber including a glass fiber and an ink layer covering the peripheral surface of the glass fiber (for example, refer to Patent Document 1 listed below).

[0003] The optical fiber described in Patent Document 1 can be identified by the color, pattern, etc. of the ink layer.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application No. 2012-508395 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] However, the ink layer is required to have excellent adhesion to the glass fiber.

[0009] In recent years, optical fibers using plastic fibers instead of glass fibers have been studied. For optical fibers using glass fibers, even if exposed to a solvent, the solvent attacks the ink layer and contacts the glass fibers, and the glass fibers bend, and cracks do not occur in the glass fibers. On the other hand, for fibers using plastic fibers, since plastics have lower solvent resistance than glass, if the solvent attacks the ink layer and contacts the plastic fibers, and the plastic fibers bend, there is a disadvantage that cracks occur.

[0010] The present invention provides a plastic optical fiber having excellent adhesion of a coloring material to a plastic optical fiber main body, excellent solvent resistance, and capable of suppressing damage.

[0011] Solutions for solving problems

[0012] The present invention (1) comprises a plastic optical fiber, which comprises a plastic optical fiber body and a coloring material covering the peripheral surface thereof, wherein the coloring material is formed by a cured product of a curable composition, wherein the curable composition comprises an active energy ray-curable multifunctional acrylate and a colorant, and the reaction rate of the vinyl group in the active energy ray-curable multifunctional acrylate in the coloring material is greater than 85%.

[0013] The present invention (2) comprises the plastic optical fiber described in (1), wherein the plastic optical fiber body comprises a contact layer in contact with the inner side surface of the coloring material, and the material of the contact layer is a polycarbonate resin and / or a cyclopolyolefin resin.

[0014] Effects of the Invention

[0015] In the plastic optical fiber of the present invention, the reaction rate of the vinyl group in the active energy ray-curable multifunctional acrylate is as high as 85% or more, so the adhesion of the coloring material to the plastic optical fiber body is excellent.

[0016] In addition, since the vinyl reaction rate of the coloring material is high, at 85% or more, even if the plastic optical fiber is exposed to a solvent, the solvent can be prevented from corroding the coloring material, thereby preventing damage to the plastic optical fiber body caused by the solvent corroding the ink layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a cross-sectional view of one embodiment of the plastic optical fiber of the present invention. DETAILED DESCRIPTION

[0018] (One embodiment of the plastic optical fiber of the present invention)

[0019] Reference Figure 1 One embodiment of the plastic optical fiber of the present invention will be described.

[0020] The plastic optical fiber 1 is longitudinally (equivalent to Figure 1 The plastic optical fiber 1 is a fiber extending in the paper depth direction. The plastic optical fiber 1 has a substantially circular shape in a cross section along a direction perpendicular to the longitudinal direction. The plastic optical fiber 1 includes a plastic optical fiber body 2 and a coloring material 3.

[0021] The plastic optical fiber main body 2 is a light transmission path that transmits light in the longitudinal direction. The plastic optical fiber main body 2 has a substantially circular shape in a cross section perpendicular to the light transmission direction.

[0022] The plastic optical fiber main body 2 includes, for example, a core portion 4 , a cladding portion 5 , and an overcladding portion 6 as an example of a contact layer in this order from the center toward the outside in a cross-sectional view.

[0023] The core 4 has a substantially circular shape in a cross-sectional view. The core 4 includes the center of the plastic optical fiber body 2 in a cross-sectional view.

[0024] The cladding portion 5 is arranged on the outer peripheral surface of the core portion 4. The cladding portion 5 is sandwiched between the core portion 4 and the over-cladding portion 6. The cladding portion 5 has a substantially annular shape in a cross-sectional view.

[0025] The refractive index of the cladding portion 5 is lower than the refractive index of the core portion 4 .

[0026] The upper cladding portion 6 is disposed on the outer peripheral surface of the cladding portion 5. The upper cladding portion 6 forms the outer peripheral surface of the plastic optical fiber body 2. The upper cladding portion 6 has a substantially annular shape in a cross-sectional view.

[0027] It should be noted that the plastic optical fiber body 2 may have a double cladding structure according to the use and purpose of the plastic optical fiber 1. Figure 1As shown by the virtual line of , the cladding portion 5 includes a first cladding portion 51 and a second cladding portion 52 arranged on the outer peripheral surface of the first cladding portion 51. That is, the cladding portion 5 has a two-layer structure of the first cladding portion 51 and the second cladding portion 52. The refractive index of the first cladding portion 51 is lower than the refractive index of the core portion 4. The refractive index of the second cladding portion 52 is lower than the refractive index of the first cladding portion 51. The refractive index of the upper cladding portion 6 is lower than the refractive index of the second cladding portion 52.

[0028] The material of the plastic optical fiber body 2 is plastic. The plastic is not particularly limited, and examples thereof include thermoplastic resins such as acrylic resins (including fluoroacrylic resins), polycarbonate resins (including modified polycarbonate resins such as polyester-modified polycarbonate resins), polyethylene resins, polypropylene resins, olefin resins such as cycloolefin resins, etc. These can be used alone or in combination. The material of the plastic optical fiber body 2 is appropriately selected according to the refractive index required for the core 4, the cladding 5, and the upper cladding 6.

[0029] As the over cladding layer 6 , polycarbonate resins and olefin resins are preferably used, and in view of high reliability, modified polycarbonate resins and cycloolefin resins are particularly preferably used.

[0030] The plastic optical fiber body 2 is transparent and has a total light transmittance of, for example, 85% or more, preferably 90% or more, more preferably 90% or more, and, for example, 100% or less.

[0031] The diameter of the plastic optical fiber main body 2 is, for example, not less than 10 μm and not more than 10 mm.

[0032] The coloring material 3 is disposed on the outer peripheral surface of the plastic optical fiber body 2. Specifically, the coloring material 3 is in contact with the outer peripheral surface of the upper cladding portion 6. The coloring material 3 forms the outer peripheral surface of the plastic optical fiber 1.

[0033] The coloring material 3 is colored. The total light transmittance of the coloring material 3 is, for example, less than 85%, preferably less than 80%, and, for example, more than 10%. Therefore, the plastic optical fiber 1 including the coloring material 3 has identification properties.

[0034] The coloring material 3 is formed of a cured product of a curable composition. The curable composition is a material of the coloring material 3, and will be described in detail in the production method below, and contains an active energy ray-curable multifunctional acrylate and a colorant.

[0035] The thickness of the coloring material 3 is not particularly limited, and is, for example, 0.01 μm or more, preferably 0.1 μm or more, and, for example, 1000 μm or less, preferably 100 μm or less. In addition, the ratio of the thickness of the coloring material 3 to the diameter of the plastic optical fiber body 2 is, for example, 0.0001 or more, preferably 0.001 or more, and, for example, 1 or less, preferably 0.5 or less.

[0036] Next, a method for producing the plastic optical fiber 1 will be described.

[0037] In this method, first, a plastic optical fiber main body 2 is prepared. The plastic optical fiber main body 2 is produced, for example, by a melt extrusion method. In the melt extrusion method, the core portion 4, the cladding portion 5, and the overcladding portion 6 are formed simultaneously.

[0038] Next, a curable composition is prepared and placed on the outer peripheral surface of the plastic optical fiber body 2 , and then the curable composition is cured.

[0039] The curable composition contains an active energy ray-curable multifunctional acrylate and a colorant.

[0040] Specifically, the curable composition contains, for example, an active energy ray-curable multifunctional acrylate, an active energy ray initiator, and a colorant.

[0041] The active energy ray-curable multifunctional acrylate has a vinyl group. Specifically, the active energy ray-curable multifunctional acrylate has a vinyl group and an aromatic ring group.

[0042] Examples of the aromatic ring group include a phenyl group and a naphthyl group, and preferably a phenyl group is used.

[0043] The active energy ray-curable multifunctional acrylates may be used alone or in combination.

[0044] When an active energy ray-curable multifunctional acrylate is used alone, the active energy ray-curable multifunctional acrylate has a vinyl group and an aromatic ring group. On the other hand, when a plurality of active energy ray-curable multifunctional acrylates are used in combination, the plurality of active energy ray-curable multifunctional acrylates all have a vinyl group; or one energy ray-curable multifunctional acrylate has a vinyl group and an aromatic ring group, and the other energy ray-curable multifunctional acrylates have a vinyl group but do not have an aromatic ring group.

[0045] The colorant is appropriately selected according to the use and purpose of the plastic optical fiber 1. As the colorant, for example, pigments and dyes can be mentioned, and preferably pigments can be mentioned. As the pigment, there is no particular limitation, for example, white pigments, black pigments, yellow pigments, green pigments, red pigments, blue pigments, etc. can be mentioned.

[0046] The blending ratio of each of the above raw materials is appropriately set according to the use and purpose of the plastic optical fiber 1. The ratio of the active energy ray-curable multifunctional acrylate in the curable composition is, for example, 50% by mass or more, preferably 75% by mass or more, and, for example, 99% by mass or less. The mass fraction of the colorant relative to 100 parts by mass of the active energy ray-curable multifunctional acrylate is, for example, 1 part by mass or more, for example, 25 parts by mass or less.

[0047] It should be noted that the prepared curable composition is allowed to contain oxygen. The curable composition is prepared in the air, and the oxygen is derived from the oxygen contained in the air.

[0048] As the curable composition, a commercially available product can be used, and for example, an optical fiber coloring ink series (manufactured by Phichem Co., Ltd.) can be used.

[0049] Next, the curable composition is applied to the outer peripheral surface of the plastic optical fiber body 2 , and then the curable composition is irradiated with active energy rays.

[0050] A known coating device is used for coating the curable composition.

[0051] Examples of active energy rays include ultraviolet rays (including UVA (long-wavelength ultraviolet rays) and UVB (short-wavelength ultraviolet rays)), α rays, β rays, γ rays, and X-rays. Preferably, ultraviolet rays are used.

[0052] For irradiation with active energy rays, an irradiation device including a light source and an irradiation chamber disposed opposite to the light source is used.

[0053] The irradiation chamber is constructed in a manner that the plastic optical fiber main body 2 coated with the curable composition can pass through. The irradiation chamber, for example, has a roughly cylindrical shape formed by a light-transmitting material (quartz, etc.). In addition, in the free radical polymerization, an inactive gas can flow into the irradiation chamber. As such a gas, nitrogen, carbon dioxide, helium, etc. can be cited, and nitrogen can be preferably cited. The gas flow rate is appropriately set according to the volume in the irradiation chamber and / or the passing speed of the plastic optical fiber main body 2 coated with the curable composition. Specifically, the gas flow rate is, for example, more than 3L / minute, preferably more than 5L / minute, more preferably more than 8L / minute, and, for example, less than 100L / minute.

[0054] In this method, the plastic optical fiber main body 2 having the curable composition coated on the outer peripheral surface is passed through the irradiation chamber of the irradiation device.

[0055] If oxygen is dissolved in the curable composition, the free radical polymerization of the vinyl in the active energy ray-curable multifunctional acrylate is hindered. However, if an inert gas is flowed into the irradiation chamber, the above-mentioned gas is dissolved in the curable composition, and the oxygen dissolved in the curable composition is driven out of the curable composition. As a result, the oxygen concentration in the curable composition is reduced. Therefore, the hindrance of the above-mentioned free radical polymerization is suppressed, and the reaction rate of the vinyl becomes high.

[0056] Thus, a cured product is produced by curing the curable composition. Thus, the coloring material 3 formed of the cured product is molded on the outer peripheral surface of the plastic optical fiber body 2 .

[0057] The reaction rate of the vinyl group in the active energy ray-curable multifunctional acrylate in the coloring material 3 is 85% or more. The reaction rate of the vinyl group is preferably 88% or more, more preferably 90% or more, further preferably 92% or more, and for example, 100% or less.

[0058] When the reaction rate of vinyl is less than 85%, the adhesion of the coloring material 3 to the plastic optical fiber body 2 is reduced. In addition, if the reaction rate of vinyl is less than 85%, the solvent resistance of the coloring material 3 is reduced. When the plastic optical fiber 1 is exposed to a solvent, if the solvent erodes the coloring material 3 and contacts the plastic optical fiber body 2, the plastic optical fiber 1 bends, and cracks are generated in the plastic optical fiber body 2.

[0059] The reaction rate of the vinyl group in the active energy ray-curable multifunctional acrylate is obtained by FT-IR based on the ATR (attenuated total reflectance spectroscopy) method. In FT-IR, the ratio of the absorbance (peak height) of the peak derived from the vinyl group to the absorbance (peak height) of the peak derived from the aromatic ring group (specifically, the phenyl group) is obtained as the "vinyl amount". Next, the reaction rate shown in the following formula is obtained.

[0060] Reaction rate (%) = [(vinyl content of the curable composition before curing) - (vinyl content of the cured product after curing)] / (vinyl content of the curable composition before curing) × 100

[0061] In the IR spectrum, the peak derived from vinyl is located at a wavelength of 810 cm -1 The peak originating from phenyl is located at a wavelength of 1510 cm -1 Place.

[0062] (Effects of one embodiment)

[0063] Furthermore, in the plastic optical fiber 1 , the reaction rate of the vinyl group in the active energy ray-curable multifunctional acrylate is high, being 85% or more. Therefore, the coloring material 3 has excellent adhesion to the plastic optical fiber body 2 .

[0064] In addition, the reaction rate of the vinyl group of the coloring material 3 is high, being 85% or more, so even if the plastic optical fiber 1 is exposed to a solvent (specifically, an organic solvent), it is possible to suppress the solvent from attacking the coloring material 3. Therefore, it is possible to suppress damage to the plastic optical fiber body 2 caused by the attack of the coloring material 3 by the solvent. Specifically, it is possible to suppress the generation of cracks in the plastic optical fiber body 2.

[0065] (Variation Example)

[0066] In the following modifications, the same reference numerals are used for the same components and processes as those in the above-mentioned embodiment, and detailed description thereof is omitted. In addition, each modification can exert the same effects as those in the embodiment except for special descriptions. Furthermore, an embodiment and its modifications can be appropriately combined.

[0067] In one embodiment, when irradiating with active energy rays, an inert gas is flowed into the irradiation chamber, but the present invention is not limited thereto, and the gas may be blown into the curable composition before coating, for example, instead of or in addition to the flow into the irradiation chamber. The method for reducing the oxygen concentration in the curable composition is not limited to the above.

[0068] In one embodiment, the vinyl amount is determined by the ratio of the absorbance of the vinyl group to the absorbance of the aromatic ring group (phenyl group). However, for example, instead of using the absorbance of the peak of the aromatic ring group, the reaction rate of the vinyl group in the cured product can be determined by the ratio of the absorbance of the vinyl group in the cured composition before curing and the absorbance of the vinyl group in the cured product after curing.

[0069] In the above embodiment, the vinyl amount is determined using the absorbance of the peak of the aromatic ring group whose amount does not change before and after the reaction as a reference. However, the vinyl amount may be determined using the peak of a group other than the aromatic ring group whose amount does not change before and after the reaction.

[0070] The plastic optical fiber 1 has a substantially circular shape in a cross-sectional view, but its shape is not particularly limited. For example, although not shown in the figure, the cross section may be a substantially rectangular shape.

[0071] Figure 1 In the figure, the plastic optical fiber body 2 includes a core 4, a cladding 5, and an upper cladding 6. However, for example, although not shown, it is also possible to include only the core 4 and the cladding 5 as an example of a contact layer without the upper cladding 6. In this case, the coloring material 3 is in contact with the outer peripheral surface of the cladding 5.

[0072] Example

[0073] Embodiment and comparative example are shown below, and the present invention is described in more detail.It should be noted that the present invention is not subject to any limitation of embodiment and comparative example.In addition, the specific numerical values ​​such as the blending ratio (ratio), physical property value, parameter used in the following description can be replaced by the upper limit (defined as "below", "not enough" numerical value) or the lower limit (defined as "above", "exceeding" numerical value) of the blending ratio (ratio), physical property value, parameter etc. recorded in the above-mentioned "specific embodiments", corresponding to them.

[0074] Example 1

[0075] A plastic optical fiber body 2 having an outer diameter of 470 μm is manufactured by a melt extrusion method and includes a core portion 4 formed of polymethyl methacrylate (PMMA) (manufactured by Mitsubishi Chemical Corporation), a cladding portion 5 formed of fluoro-PMMA (FM450 manufactured by DAIKIN INDUSTRIES, Ltd.), and an upper cladding portion 6 formed of XYLEXX7300CL (product name, manufactured by SABIC Innovative Plastics, polyester-modified polycarbonate resin).

[0076] Next, optical fiber coloring ink blue (containing active energy ray-curable multifunctional acrylate and blue pigment, manufactured by Phichem Co., Ltd.) was prepared as a curable composition.

[0077] Then, a coating device and an irradiation device are sequentially provided on the downstream side in the conveying direction. The coating device has a coating port with an inner diameter of 510 μm. The irradiation device has a microwave-excited D lamp as a light source and a quartz passage tube as an irradiation chamber.

[0078] The curable composition was placed in a coating device (mold diameter: 510 μm). In addition, nitrogen gas was allowed to flow through the irradiation device at a flow rate of 5 L / min.

[0079] Next, the plastic optical fiber body was passed through a coating device to coat the curable composition on the peripheral surface of the plastic optical fiber body. Then, an irradiation device (D lamp manufactured by FUSION Co., Ltd.) was used to irradiate the plastic optical fiber body at a temperature of 331 mJ / cm 2 The curable composition is cured by irradiating ultraviolet rays with an energy of 1000 μm to form the coloring material.

[0080] Example 2 to Comparative Example 3

[0081] The plastic optical fiber 1 was obtained by performing the same treatment as in Example 1 except that the method for producing the plastic optical fiber 1 was changed according to the description in Table 1.

[0082] evaluate

[0083] The following items were evaluated for the plastic optical fibers 1 of the respective examples and comparative examples.

[0084] (Adhesion)

[0085] A double-sided adhesive tape (manufactured by Nitto Denko Corporation, No. 500) was attached to the surface of the rectangular plate.

[0086] Next, five plastic optical fibers 1 each having a length of 5 cm in the longitudinal direction were arranged side by side on the adhesive surface of the front side of the double-sided adhesive tape, and then pressed against the double-sided adhesive tape with fingers.

[0087] Thereafter, the plastic optical fiber 1 is cut with a cutter along the parallel direction of the plastic optical fiber 1. A plurality of cuts are made at intervals of 0.5 mm in the longitudinal direction. Thus, one plastic optical fiber 1 is divided into 10 units (masses).

[0088] Then, a single-sided adhesive tape (Nitto Denko Corporation, No. 5000NS) was attached to these plastic optical fibers and pressed with a 1 kg roller. Then, the single-sided adhesive tape was peeled off from the plastic optical fiber 1 at a peeling speed of 1000 mm / min or more. The number of repetitions was set to 2.

[0089] Thereafter, the units (blocks) of the portion where the coloring material 3 was peeled off were counted.

[0090] The percentage of the number of peeled units (blocks) was calculated as the peeling rate (%).

[0091] ◎: The peeling rate is 0%.

[0092] ○: The peeling rate is 1% or more and 40% or less.

[0093] ×: The peeling rate is 41% or more.

[0094] (Reactivity of vinyl)

[0095] The coloring material 3 (cured product after curing) of the plastic optical fiber 1 was subjected to FT-IR measurement by the ATR method to obtain a spectrum. The conditions and the like of FT-IR are described below.

[0096] FT-IR: Nicolet4700 manufactured by Thermo Fisher Scientific

[0097] Cumulative number of times: 32

[0098] Detector: DTGS

[0099] According to the obtained spectrum, the 1510 cm -1 The absorbance (peak height) of the vinyl group is 810 cm -1Then, the peak height at 810 cm derived from the vinyl group (peak height) was calculated. -1 The absorbance is relative to 1510 cm-1 derived from phenyl -1 The ratio of the absorbance (peak height) of the vinyl group was taken as the vinyl amount.

[0100] Furthermore, the same operation as that of the coloring material 3 was carried out on the cured composition before coating, and the above absorbance ratio was determined as the vinyl group amount.

[0101] Thereafter, the reaction rate of the vinyl group was determined according to the following formula.

[0102] Reaction rate of vinyl group (%) = [(vinyl group amount of curable composition before curing) - (vinyl group amount of cured product after curing)] / (vinyl group amount of curable composition before curing) × 100

[0103] (Solvent resistance)

[0104] The plastic optical fiber 1 having a length of 1 m in the longitudinal direction is placed in a vat of 250 mm×350 mm in a state where it is bent into an arc shape having a curvature radius of 10 mm or more.

[0105] Next, diisononyl phthalate (solvent) is injected into the disk so that the middle portion in the longitudinal direction of the plastic optical fiber 1 is completely covered.

[0106] Thereafter, the tray was left standing at room temperature for 1 day, and thereafter, the plastic optical fiber 1 was taken out from the tray.

[0107] The taken-out plastic optical fiber 1 was observed with an optical microscope (manufactured by KEYENCE CORPORATION, "VHX-950F", lens: VH-Z100R), and the solvent resistance was evaluated according to the following criteria.

[0108] ○: No cracks were observed in the plastic optical fiber main body 2 .

[0109] ×: Generation of cracks was observed in the plastic optical fiber main body 2 .

[0110] [Table 1]

[0111] Table 1

[0112]

[0113] It should be noted that the above invention is provided as an exemplary embodiment of the present invention, but this is merely an example and is not to be construed as limiting. Modifications of the present invention that are obvious to a person skilled in the art are also included in the above claims.

[0114] Industrial Applicability

[0115] Plastic optical fibers can be used in various optical transmissions.

[0116] Description of Reference Numerals

[0117] 1 Plastic Optical Fiber

[0118] 2 Plastic optical fiber body

[0119] 3 Coloring Materials

[0120] 6 Upper cladding layer (an example of a contact layer)

Claims

1. A plastic optical fiber, characterized in that: It has a plastic optical fiber body and a coloring material covering its peripheral surface. The coloring material is formed of a cured product of a curable composition, wherein the curable composition comprises an active energy ray-curable multifunctional acrylate and a coloring agent. The reaction rate of the vinyl groups in the active energy ray-curable multifunctional acrylate in the coloring material is 85% or more, The plastic optical fiber body includes a contact layer in contact with the inner side of the coloring material, The material of the contact layer is polycarbonate resin.

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