OPTICAL PLASTIC FIBER

Abstract

An optical polymer fiber 10 of the present disclosure comprises a core 11 and a cladding 12 arranged on an outer circumference of the core 11. The optical polymer fiber 10 has a length of 30 m or less. The core 11 has a diameter of 30 µm or more and 100 µm or less. The optical polymer fiber 10 has a transmission loss at a wavelength of 850 nm of 70 dB / km or more and 500 dB / km or less, and a transmission band at a wavelength of 850 nm is 30 MHz·km or more and 600 MHz·km or less.

Description

TECHNICAL FIELD

[0001] The present invention relates to a plastic optical fiber. STATE OF THE ART

[0002] Plastic optical fibers include a core, which is a light-transmitting section located in a central portion, and a cladding coating an outer periphery of the core. The core is made of a resin material with a high refractive index. The cladding is made of a resin material with a lower refractive index than the core resin material, so that light remains within the core.

[0003] In recent years, cables capable of transmitting large amounts of data have also become necessary for short-distance communication, for example, within the home. Therefore, the use of plastic optical fibers capable of transmitting large volumes of communication signals is being considered for short-distance transmission.

[0004] However, the use of plastic optical fibers for short-distance signal transmission introduces a new problem related to signal quality, which has not been considered in the case of long-distance use. Therefore, for example, Patent Literature 1 proposes an optical fiber with a length of 100 m or less and a 2 -value of 1.7 or more as an optical fiber suitable for reducing noise in short-distance transmission and enabling high-quality signal transmission. It should be noted that the M2 -value is a parameter used as a parameter representing the quality of a light beam. CITATION LISTPatent literature

[0005] Patent Literature 1: JP 2019-049658 A SUMMARY OF THE INVENTIONTechnical problem

[0006] The bit error rate (BER) is a measure of signal transmission quality (hereinafter referred to as "transmission quality"). The BER represents how many of the transmitted 0 and 1 signals were received in error and is determined as the ratio of the number of bit errors to the number of transmitted bits (number of bit errors / number of transmitted bits). An optical fiber with a low BER can exhibit high transmission quality.

[0007] As described above, the optical fiber disclosed in Patent Literature 1 can be formed by using a M 2-value of 1.7 or more can reduce the noise. However, even an optical fiber that has such a M 2 -value and thus achieves a reduction in noise, in some cases unsuitable for achieving a low BER. This means that only the M 2 Increasing the BER value is insufficient to reduce the BER, and conventional optical fibers leave room for improvement in terms of transmission quality.

[0008] The present disclosure therefore aims to provide a plastic optical fiber with improved transmission quality in short-distance signal transmission. Solution to the task

[0009] The present disclosure provides a plastic optical fiber comprising: a core and a jacket arranged on an outer circumference of the core, wherein the plastic optical fiber has a length of 30 m or less, the core has a diameter of 30 µm or more and 100 µm or less, a transmission loss at a wavelength of 850 nm is 70 dB / km or more and 500 dB / km or less and a transmission band at a wavelength of 850 nm is 30 MHz·km or more and 600 MHz·km or less. Advantageous effects of the invention

[0010] The present disclosure can provide a plastic optical fiber with improved transmission quality in short-distance signal transmission. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram showing an example of a cross-sectional structure of a plastic optical fiber according to an embodiment of the present disclosure. Fig.2 is a schematic diagram showing another example (first modification) of the cross-sectional structure of the plastic optical fiber according to the embodiment of the present disclosure. Fig. 3 is a schematic diagram showing still another example (second modification) of the cross-sectional structure of the plastic optical fiber according to the embodiment of the present disclosure. Fig. 4 is a schematic cross-sectional view showing an example of a manufacturing apparatus that can be used to manufacture the plastic optical fiber according to the embodiment of the present disclosure. DESCRIPTION OF THE EMBODIMENTS

[0011] A first aspect of the present disclosure is a plastic optical fiber comprising: a core and a jacket arranged on an outer circumference of the core, wherein the plastic optical fiber has a length of 30 m or less, the core has a diameter of 30 µm or more and 100 µm or less, a transmission loss at a wavelength of 850 nm is 70 dB / km or more and 500 dB / km or less and a transmission band at a wavelength of 850 nm is 30 MHz·km or more and 600 MHz·km or less.

[0012] According to a second aspect of the present disclosure, the plastic optical fiber according to the first aspect is, for example, a graded index plastic optical fiber.

[0013] According to a third aspect of the present disclosure, in the plastic optical fiber according to the first or second aspect, for example, the core includes a first resin, and the first resin is at least one selected from the group consisting of a fully fluorinated resin, a partially fluorinated resin, a partially chlorinated resin, and a partially deuterated resin.

[0014] According to a fourth aspect of the present disclosure, the first resin in the plastic optical fiber according to the third aspect is, for example, at least one selected from the group consisting of the fully fluorinated resin and the partially fluorinated resin.

[0015] According to a fifth aspect of the present disclosure, the first resin in the plastic optical fiber according to the fourth aspect includes, for example, a fluorine-containing polymer including a structural unit (A) represented by the following formula (1): wherein R ff 1 to Rff 4 each independently represents a fluorine atom, a perfluoroalkyl group having 1 to 7 carbon atoms or a perfluoroalkyl ether group having 1 to 7 carbon atoms and R ff 1 and R ff 2 are optionally linked to form a ring.

[0016] According to a sixth aspect of the present disclosure, the fluorine-containing polymer in the plastic optical fiber according to the fifth aspect further includes, for example, a structural unit (B) represented by the following formula (2): wherein R 1 to R 3 each independently represents a fluorine atom or a perfluoroalkyl group having 1 to 7 carbon atoms, R 4represents a perfluoroalkyl group having 1 to 7 carbon atoms, the perfluoroalkyl group optionally has a ring structure, one or some of the fluorine atoms are each optionally substituted by a halogen atom other than a fluorine atom, and one or some of the fluorine atoms in the perfluoroalkyl group are each optionally substituted by a halogen atom other than a fluorine atom.

[0017] According to a seventh aspect of the present disclosure, the fluorine-containing polymer in the plastic optical fiber according to the fifth or sixth aspect includes, for example, a structural unit (C) represented by the following formula (3): wherein R 5 to R 8each independently represents a fluorine atom or a perfluoroalkyl group having 1 to 7 carbon atoms, the perfluoroalkyl group optionally has a ring structure, one or some of the fluorine atoms are each optionally substituted by a halogen atom other than a fluorine atom, and one or some of the fluorine atoms in the perfluoroalkyl group are each optionally substituted by a halogen atom other than a fluorine atom.

[0018] According to an eighth aspect of the present disclosure, the fluorine-containing polymer in the plastic optical fiber according to any one of the fifth to seventh aspects further includes, for example, a structural unit (D) represented by the following formula (4): wherein Z represents an oxygen atom, a single bond, or -OC(R 19 R 20 )O- represents, R 9 to R 20each independently represents a fluorine atom, a perfluoroalkyl group having 1 to 5 carbon atoms or a perfluoroalkoxy group having 1 to 5 carbon atoms, one or some of the fluorine atoms are each optionally substituted by a halogen atom other than a fluorine atom, one or some of the fluorine atoms in the perfluoroalkyl group are each optionally substituted by a halogen atom other than a fluorine atom, one or some of the fluorine atoms in the perfluoroalkoxy group are each optionally substituted by a halogen atom other than a fluorine atom, s and t are each independently 0 to 5 and s + t is an integer from 1 to 6 or in the case that Z is -OC(R 19 R 20 )O-is, s + t is optionally 0.

[0019] According to a ninth aspect of the present disclosure, in the plastic optical fiber according to any one of the third to eighth aspects, for example, the core further includes a refractive index modifier.

[0020] According to a tenth aspect of the present disclosure, the plastic optical fiber according to any one of the first to ninth aspects, for example, further includes a reinforcing layer disposed on an outer periphery of the cladding.

[0021] An embodiment of a plastic optical fiber (hereinafter referred to as "POF") of the present disclosure will be described. The POF of the present disclosure includes a core and a cladding disposed on an outer periphery of the core. The POF of the present embodiment is, for example, a gradient index (GI) POF.

[0022] Fig. 1 shows an example of a cross-sectional structure of the POF according to the present embodiment.

[0023] One in Fig. The POF 10 shown in Fig. 1 includes a core 11 and a cladding 12 arranged on an outer circumference of the core 11.

[0024] The POF 10 of the present embodiment has a length of 30 m or less. Here, the length of the POF 10 refers to an axial length of the POF 10. That is, the POF 10 of the present embodiment is used for short-distance signal transmission and is also applicable, for example, to indoor use. Moreover, the core 11 in the POF 10 of the present embodiment has a diameter of 30 μm or more and 100 μm or less. In the POF 10 of the present embodiment having such a length and core diameter, the transmission loss at a wavelength of 850 nm is 70 dB / km or more and 500 dB / km or less, and a transmission band at a wavelength of 850 nm is 30 MHz·km or more and 600 MHz·km or less.

[0025] Here, the diameter (hereinafter referred to as "core diameter") of the core 11 refers to a diameter at which the light intensity measured by a near-field pattern (NFP) method, which is one of the methods specified in IEC 60793-1-20 and IEC 60793-2-40 subcategory A4h, using light with a wavelength of 850 nm is 5%. The transmission attenuation of the POF 10 at a wavelength of 850 nm is a value measured by a cut-back method, which is one of the methods specified in IEC 60793-1-40. The transmission band of the POF 10 is a value measured by a pulse method, which is one of the methods specified in IEC 60793-1-41.

[0026] Since the transmission attenuation and transmission band of the POF 10 of the present embodiment satisfy the above ranges, the POF 10 of the present embodiment can achieve a low BER despite its short length and small core diameter, which fall within the above-described ranges where noise is relatively likely to be generated. The BER, as described above, is the ratio of the number of bit errors to the number of transmitted bits (number of bit errors / number of transmitted bits) and is a measure of the transmission quality. A low BER means high transmission quality. Therefore, the POF 10 of the present embodiment can achieve improved transmission quality in short-distance signal transmission. The BER of the POF 10 is preferably 1 × 10 -7 or less and more preferably 1 × 10 -8 or less.

[0027] As described above, the length of the POF 10 of the present embodiment is 30 m or less. The length of the POF 10 of the present embodiment may be, for example, 20 m or less, 15 m or less, or 10 m or less. The POF 10 of the present embodiment can achieve high transmission quality even when the POF 10 is intended for short-distance use as described above. The length of the POF 10 of the present embodiment is required to be more than 0 m, and it may be, for example, 0.1 m or more.

[0028] As described above, the core diameter of the POF 10 of the present embodiment is 30 µm or more and 100 µm or less. The core diameter may be 80 µm or less, 60 µm or less, or 55 µm or less. The core diameter may be 40 µm or more or 45 µm or more.

[0029] As described above, the transmission loss at a wavelength of 850 nm of the POF 10 of the present embodiment is 70 dB / km or more and 500 dB / km or less, and the transmission band at a wavelength of 850 nm is 30 MHz·km or more and 600 MHz·km or less. The transmission loss and the transmission band are each a factor affecting the BER. The transmission loss also correlates with noise. Therefore, by controlling the transmission loss within the above range, the noise is indirectly controlled within a reasonable range. Controlling the transmission loss and the transmission band within the above ranges in combination can reduce the BER of the POF 10 of the present embodiment.Accordingly, a preferable combination of the transmission loss and transmission band ranges can be determined, for example, by considering a material (e.g., resin type) of the core 11.

[0030] The transmission loss at a wavelength of 850 nm is preferably 70 dB / km or more and 400 dB / km or less, more preferably 70 dB / km or more and 350 dB / km or less, even more preferably 80 dB / km or more and 300 dB / km or less.

[0031] The transmission band at a wavelength of 850 nm is preferably 50 MHz·km or more and 580 MHz·km or less, more preferably 60 MHz·km or more and 560 MHz·km or less, even more preferably 70 MHz·km or more and 540 MHz·km or less.

[0032] The transmission loss of the POF 10 of the present embodiment can be regulated within the above range, for example, by conditions for manufacturing the POF 10, specifically, for example, by filtering conditions for removing foreign matter such as minute undesirable substances from the materials of the POF 10 (for example, the materials of the core 11 and the cladding 12). Filtering conditions appropriate for the transmission loss at a wavelength of 850 nm to be 70 dB / km or more and 500 dB / km or less can be determined, for example, by considering the type of resin to be used as the material and an additive such as a refractive index modifier.

[0033] Furthermore, it is preferable that, for example, the material of the POF 10 (for example, the material of the core 11 and the material of the cladding 12) is subjected to high-temperature heat treatment so that the POF 10 of the present embodiment has a transmission loss in the above range. Through the heat treatment, organic impurities such as a by-product of resin synthesis can be removed. Such organic impurities cause scattering. Consequently, through the high-temperature heat treatment, a POF 10 can be obtained that has a lower transmission loss and contains a reduced amount of an organic scatterer. The temperature of the heat treatment depends, for example, on the types of resins used as the materials of the core 11 and the cladding 12.For example, when the glass transition temperature of the resin used is expressed as Tg, the heat treatment temperature is preferably Tg + 70°C or higher, more preferably Tg + 90°C or higher, and even more preferably Tg + 110°C or higher. For example, when a polymer of perfluoro-4-methylene-1,3-dioxolane is used, as in the following EXAMPLES, the heat treatment temperature is preferably 220°C or higher, more preferably 240°C or higher, and even more preferably 250°C or higher.

[0034] The transmission band of the POF 10 of the present embodiment can be controlled within the above range by, for example, controlling a refractive index distribution of the core 11. Specifically, conditions for diffusing a refractive index modifier into the material of the core 11, which are appropriate so that the transmission band is 30 MHz·km or more and 600 MHz·km or less, can be determined, for example, by considering the type of resin used as the material and the refractive index modifier. The conditions for diffusing the refractive index modifier include, for example, the time required for a fiber structure, which is a precursor to the POF 10, to pass through a diffusion tube, the length of the diffusion tube, the setting temperature of the diffusion tube, and the rotation speed.

[0035] It is preferable that the POF 10 of the present embodiment has a first end into which light enters and a second end from which light exits, and that the M 2 -value of the light exiting from the second end side is 1.7 or more. As described in JP 2019-049658 A (Patent Literature 1), which is a previous application of the applicant of the present invention, the optical feedback spatially expands from the second end, which is an exit end, to the first end, which is an entrance end, and the amount of light returning to a light source such as a VCSEL is reduced by reducing the M 2 -value, which was used as a parameter representing the quality of a light beam, is applied to a design value of an optical fiber for short-distance communication, in other words, by the M 2-value is regulated to 1.7 or more. Thus, the optical feedback noise can be reduced. For this reason, the POF 10 of the present embodiment, when it has an M 2 -value of 1.7 or more, further improve the transmission quality. The upper limit of the M 2 -value is not particularly limited and can be, for example, 6 or less or 5 or less. The M 2 -value can be regulated to a desired value, for example, by the type of material of the core 11 and the conditions for producing the POF 10.

[0036] The respective components of the POF 10 of the present embodiment will be described in more detail below. (Core 11)

[0037] The core 11 is a section configured to transmit light. The core 11 has a higher refractive index than that of the cladding 12. As a result, light incident on the core 11 is trapped inside the core 11 by the cladding 12 and propagates into the POF 10.

[0038] The core 11 includes a first resin. The core 11 may include the first resin as its main component. Here, the fact that the core 11 includes the first resin as its main component means that the first resin is a component whose content is the highest by mass in the core 11. The content of the first resin in the core 11 may be 75% by mass or more, 80% by mass or more, or 85% by mass or more.

[0039] The core 11 may further include an additive in addition to the first resin. The additive is, for example, a refractive index modifier. That is, the core 11 may be made of a resin composition including the first resin and the additive such as the refractive index modifier. The refractive index modifier may, for example, be a known refractive index modifier used as the material of the core 11 of the POF 10. The material of the core 11 may include an additive other than the refractive index modifier.

[0040] For example, if the POF 10 of the present embodiment is a GI-POF, the core 11 has a refractive index distribution in which the refractive index changes in the radius direction. Such a refractive index distribution can be formed, for example, by adding the refractive index modifier to the first resin and diffusing the refractive index modifier into the interior of the first resin (for example, by thermal diffusion).

[0041] The first resin contained in the core 11 is not limited to a specific resin, as long as the first resin is a resin with high transparency. Examples of the first resin include fluorine-containing resins, acrylic resins such as methyl methacrylate, styrene resins, and carbonate resins.

[0042] The first resin contained in the core 11 may be at least one selected from the group consisting of a fully fluorinated resin, a partially fluorinated resin, a partially chlorinated resin, and a partially deuterated resin. A partially fluorinated resin, a partially chlorinated resin, and a partially deuterated resin each refer herein to a resin based on a resin known as a core material of POFs in this technical field, in which one or some of the hydrogen atoms in CH bonds are fluorinated, chlorinated, or deuterated. A fully fluorinated resin refers herein to a resin based on a resin known as a core material of POFs in this technical field, in which each hydrogen atom in CH bonds is fluorinated. Examples of resins known as core materials in this technical field include, as described above, acrylic resins such as methyl methacrylate, styrene resins, and carbonate resins.A polymer having an aliphatic ring structure such as a polymer having a dioxolane structure can be used.

[0043] The first resin is desirably at least one selected from the group consisting of a fully fluorinated resin and a partially fluorinated resin. That is, the first resin is desirably a fluorine-containing resin.

[0044] The first resin of the core 11 is preferably a fluorine-containing resin enclosing a fluorine-containing polymer. Hereinafter, the fluorine-containing resin enclosed in the core 11 is referred to as the first fluorine-containing resin, and the fluorine-containing polymer enclosed in the first fluorine-containing resin is referred to as the first fluorine-containing polymer.

[0045] From the viewpoint of reducing light absorption attributable to the stretching energy of a CH bond, it is preferable that the first fluorine-containing polymer included in the first fluorine-containing resin be substantially free of a hydrogen atom, and it is particularly preferable that each hydrogen atom bonded to a carbon atom be substituted by a fluorine atom. That is, it is preferable that the first fluorine-containing polymer be substantially free of a hydrogen atom and be fully fluorinated. Herein, the fluorine-containing polymer being substantially free of a hydrogen atom means that the hydrogen atom content in the fluorine-containing polymer is 1 mol% or less.

[0046] The first fluorine-containing polymer preferably has a fluorine-containing aliphatic ring structure. The fluorine-containing aliphatic ring structure may be included in a main chain of the fluorine-containing polymer or may be included in a side chain of the first fluorine-containing polymer. The first fluorine-containing polymer has, for example, a structural unit (A) represented by the following formula (1).

[0047] In formula (1), R ff 1 to R ff 4 each independently represents a fluorine atom, a perfluoroalkyl group having 1 to 7 carbon atoms or a perfluoroalkyl ether group having 1 to 7 carbon atoms. R ff 1 and R ff 2are optionally linked to form a ring. "Perfluoro" indicates that each hydrogen atom bonded to a carbon atom is substituted by a fluorine atom. In formula (1), the number of carbon atoms in the perfluoroalkyl group is preferably 1 to 5, more preferably 1 to 3, and even more preferably 1. The perfluoroalkyl group may be linear or branched. Examples of the perfluoroalkyl group include a trifluoromethyl group, a pentafluoroethyl group, and a heptafluoropropyl group.

[0048] In formula (1), the number of carbon atoms in the perfluoroalkyl ether group is preferably 1 to 5, and more preferably 1 to 3. The perfluoroalkyl ether group may be linear or branched. Examples of the perfluoroalkyl ether group include a perfluoromethoxymethyl group.

[0049] In case R ff 1 and R ff 2are linked to form a ring, the ring can be a five-membered ring or a six-membered ring. Examples of the ring include a perfluorotetrahydrofuran ring, a perfluorocyclopentane ring, and a perfluorocyclohexane ring.

[0050] Specific examples of the structural unit (A) include structural units represented by the following formulas (A1) to (A8).

[0051] Among the structural units represented by the above formulas (A1) to (A8), the structural unit (A) is preferably the structural unit (A2), that is, a structural unit represented by the following formula (5).

[0052] The first fluorine-containing polymer may include one or more structural units (A). In the first fluorine-containing polymer, the amount of the structural unit (A) is preferably 20 mol% or more, and more preferably 40 mol% or more, of a total amount of all the structural units. When it includes 20 mol% or more of the structural unit (A), the first fluorine-containing polymer tends to have much higher heat resistance. When it includes 40 mol% or more of the structural unit (A), the first fluorine-containing polymer tends to have much higher transparency and much higher mechanical strength in addition to high heat resistance. In the first fluorine-containing polymer, the amount of the structural unit (A) is preferably 95 mol% or less, and more preferably 70 mol% or less, of the total amount of all the structural units.

[0053] The structural unit (A) is derived, for example, from a compound represented by the following formula (6). In formula (6), R ff 1 to R ff 4 as described in formula (1). It should be noted that the compound represented by formula (6) can be obtained, for example, by a previously known production method such as a production method disclosed in JP 2007-504125 A.

[0054] Specific examples of the compound represented by the above formula (6) include compounds represented by the following formulas (M1) to (M8).

[0055] The fluorine-containing polymer may further comprise an additional structural unit other than the structural unit (A). Examples of the additional structural unit include the following structural units (B) to (D).

[0056] The structural unit (B) is represented by the following formula (2).

[0057] In formula (2), R 1 to R 3 each independently represents a fluorine atom or a perfluoroalkyl group having 1 to 7 carbon atoms. R 4 represents a perfluoroalkyl group having 1 to 7 carbon atoms. The perfluoroalkyl group optionally has a ring structure. One or some of the fluorine atoms are each optionally substituted by a halogen atom other than a fluorine atom. One or some of the fluorine atoms in the perfluoroalkyl group are each optionally substituted by a halogen atom other than a fluorine atom.

[0058] The fluorine-containing polymer may include one or more structural units (B). In the fluorine-containing polymer, the amount of the structural unit (B) is preferably 5 to 10 mol% of the total amount of all structural units. The amount of the structural unit (B) may be 9 mol% or less or 8 mol% or less.

[0059] The structural unit (B) is derived, for example, from a compound represented by the following formula (7). In formula (7), R 1 to R 4 as described for formula (2). The compound represented by formula (7) is a fluorine-containing vinyl ether such as a perfluorovinyl ether.

[0060] The structural unit (C) is represented by the following formula (3).

[0061] In formula (3), R 5 to R 8 each independently represents a fluorine atom or a perfluoroalkyl group having 1 to 7 carbon atoms. The perfluoroalkyl group optionally has a ring structure. One or some of the fluorine atoms are each optionally substituted by a halogen atom other than a fluorine atom. One or some of the fluorine atoms in the perfluoroalkyl group are each optionally substituted by a halogen atom other than a fluorine atom.

[0062] The fluorine-containing polymer may include one or more structural units (C). In the fluorine-containing polymer, the amount of the structural unit (C) is preferably 5 to 10 mol% of the total amount of all structural units. The amount of the structural unit (C) may be 9 mol% or less or 8 mol% or less.

[0063] The structural unit (C) is derived, for example, from a compound represented by the following formula (8). In formula (8), R 5 to R 8 as described for formula (3). The compound represented by formula (8) is a fluorine-containing olefin such as tetrafluoroethylene or chlorotrifluoroethylene.

[0064] The structural unit (D) is represented by the following formula (4).

[0065] In formula (4), Z represents an oxygen atom, a single bond or -OC(R 19 R 20 )O- dar and R 9 to R 20each independently represents a fluorine atom, a perfluoroalkyl group having 1 to 5 carbon atoms, or a perfluoroalkoxy group having 1 to 5 carbon atoms. One or some of the fluorine atoms are each optionally substituted by a halogen atom other than a fluorine atom. One or some of the fluorine atoms in the perfluoroalkyl group are each optionally substituted by a halogen atom other than a fluorine atom. One or some of the fluorine atoms in the perfluoroalkoxy group are each optionally substituted by a halogen atom other than a fluorine atom. The symbols s and t are each independently 0 to 5, and s + t is an integer from 1 to 6, or in the case where Z is -OC(R 19 R 20 )O-, s + t is optionally 0.

[0066] The structural unit (D) is preferably represented by the following formula (9). The structural unit represented by the following formula (9) is a structural unit represented by the above formula (4), wherein Z is an oxygen atom, s is 0, and t is 2.

[0067] In formula (9), R 141 , R142, R 151 and R 152 each independently represents a fluorine atom, a perfluoroalkyl group having 1 to 5 carbon atoms, or a perfluoroalkoxy group having 1 to 5 carbon atoms. One or some of the fluorine atoms are each optionally substituted by a halogen atom other than a fluorine atom. One or some of the fluorine atoms in the perfluoroalkyl group are each optionally substituted by a halogen atom other than a fluorine atom. One or some of the fluorine atoms in the perfluoroalkoxy group are each optionally substituted by a halogen atom other than a fluorine atom.

[0068] The fluorine-containing polymer may include one or more structural units (D). In the fluorine-containing polymer, the amount of the structural unit (D) is preferably 30 to 67 mol% of the total amount of all structural units. For example, the amount of the structural unit (D) is 35 mol% or more, and may be 60 mol% or less, or 55 mol% or less.

[0069] The structural unit (D) is derived, for example, from a compound represented by the following formula (10). In formula (10), Z, R 9 to R 18 , s and t are as described for formula (4). The compound represented by formula (10) is a cyclopolymerizable fluorine-containing compound having two or more polymerizable double bonds.

[0070] The structural unit (D) is preferably derived from a compound represented by the following formula (11). In formula (11), R 141 , R 142 , R 151and R 152 as described for formula (9).

[0071] Specific examples of the compound represented by formula (10) or formula (11) include the following compounds. CF2=CFOCF 2C F=CF2 CF2=CFOCF (CF3) CF=CF2 CF2=CFOCF2CF2CF=CF2 CF2=CFOCF2CF (CF3) CF=CF2 CF2=CFOCF (CF3) CF2CF=CF2 CF2=CFOCFClCF2CF=CF2 CF2=CFOCCl2CF2CF=CF2 CF2=CFOCF2OCF=CF2 CF2=CFOC (CF3) 2OCF=CF2 CF2=CFOCF2CF (OCF3) CF=CF2 CF2=CFCF2CF=CF2 CF2=CFCF2CF2CF=CF2 CF2=CFCF2OCF2CF=CF2 CF2=CFOCF2CFClCF=CF2 CF2=CFOCF2CF2CCl=CF2 CF2=CFOCF2CF2CF=CFCl CF2=CFOCF2CF (CF3) CCl=CF2 CF2=CFOCF2OCF=CF2 CF2=CFOCCl2OCF=CF2 CF2=CClOCF2OCCl=CF2

[0072] The first fluorine-containing polymer may further include an additional structural unit other than the structural units (A) to (D). However, the first fluorine-containing polymer is preferably substantially free of an additional structural unit other than the structural units (A) to (D). The fact that the fluorine-containing polymer is substantially free of an additional structural unit other than the structural units (A) to (D) means that the sum of the amounts of the structural units (A) to (D) is 95 mol% or more, and preferably 98 mol% or more, of the total amount of all the structural units in the fluorine-containing polymer.

[0073] The polymerization method for the first fluorine-containing polymer is not particularly limited, and, for example, a conventional polymerization method such as radical polymerization can be used. A polymerization initiator for the polymerization of the fluorine-containing polymer can be a fully fluorinated compound.

[0074] The first fluorine-containing polymer forms the first fluorine-containing resin used as the first resin. A first glass transition temperature Tg1 of the first resin is, for example, 100°C to 140°C, and may be, but is not limited to, 105°C or higher or 120°C or higher. Herein, the term "glass transition temperature" refers to a midpoint glass transition temperature (T mg ), determined according to JIS K 7121: 1987.

[0075] The refractive index of the core 11 is not limited to a specific value, as long as the refractive index of the core 11 is higher than the refractive index of the cladding 12. To achieve a POF 10 with a high numerical aperture, it is preferable that the difference between the refractive index of the core 11 and the refractive index of the cladding 12 at a wavelength of the used light be large. For example, the refractive index of the core 11 may be 1.320 or more, or even 1.330 or more at a wavelength of the used light (e.g., a wavelength of 850 nm). The upper limit of the refractive index of the core 11 is, for example, 1.4000 or less, but is not particularly limited thereto. (Coat 12)

[0076] In the POF 10 of the present embodiment, for example, the cladding 12 includes a second resin. The cladding 12 may include the second resin as its main component. Herein, the inclusion of the second resin as its main component means that the second resin is a component whose content is the highest by mass in the cladding 12. The content of the second resin in the cladding 12 may be 80 mass% or more, 90 mass% or more, or 95 mass% or more. The cladding 12 may be made of the second resin. The cladding 12 may further include an additive in addition to the second resin.

[0077] The second resin enclosed in the shell 12 is not limited to a specific resin, as long as the second resin has high transparency. Examples of the second resin are the same as those presented as examples of the resin that can be used as the first resin. As with the first resin, a fluorine-containing resin is suitably used as the second resin.

[0078] The second resin of the sheath 12 is preferably a fluorine-containing resin enclosing a fluorine-containing polymer. Hereinafter, the fluorine-containing resin enclosed in the sheath 12 is referred to as the second fluorine-containing resin, and the fluorine-containing polymer enclosed in the second fluorine-containing resin is referred to as the second fluorine-containing polymer.

[0079] Examples of the fluorine-containing resin that can be used as the second fluorine-containing resin are the same as those cited as examples of the fluorine-containing resin that can be used as the first fluorine-containing resin. That is, examples of the fluorine-containing polymer that can be used as the second fluorine-containing polymer are the same as those cited as examples of the fluorine-containing polymer that can be used as the first fluorine-containing polymer.

[0080] The second fluorine-containing polymer forms the second fluorine-containing resin used as the second resin. As described above, a second glass transition temperature Tg2 of the second resin is not particularly limited and is, for example, 100°C to 150°C, and may be 105°C or higher or 125°C or higher.

[0081] It is preferable that the second resin, which may be a resin different from the first resin, has an affinity with the first resin. For example, the second resin may include the same polymerization unit as that in the first resin, or it may be the same as the first resin. In these cases, delamination is less likely to occur at the interface between the core 11 and the cladding 12, and transmission loss, for example, may be reduced.

[0082] The refractive index of the cladding 12 is not limited to a specific value, as long as the refractive index of the cladding 12 is determined based on the refractive index of the core 11. The cladding 12 may have a refractive index of, for example, 1.340 or less, 1.330 or less, 1.320 or less at a wavelength of the light used (e.g., a wavelength of 850 nm).

[0083] Fig.Figure 2 shows a first modification of the POF of the present embodiment. A POF 20 as shown in Fig. 2, has a configuration in which the POF 10 is further provided with a reinforcing layer 21 disposed on an outer periphery of the cladding 12. The reinforcing layer 21 is provided to improve the mechanical strength of the POF 10. For example, a material and reinforcing layer configuration of a known POF can be applied for the reinforcing layer 21. Examples of the material of the reinforcing layer 21 include various engineering plastics such as a polycarbonate, a polyester, a cycloolefin polymer, a cycloolefin copolymer, polytetrafluoroethylene (PTFE), a modified PTFE, a tetrafluoroethylene-perfluoroalkoxyethylene (PFA) copolymer, a copolymer thereof, and a mixture thereof.

[0084] The cladding of the POF of the present embodiment may, for example, be composed of a plurality of layers. For example, the POF of the present embodiment may be a POF 30 including the core 11, a cladding 32 disposed on the outer periphery of the core, and a coating layer 21 disposed on the outer periphery of the cladding, as shown in a Fig. 3. The cladding 32 of the POF 30 has a double cladding structure in which a two-layer structure composed of a first cladding layer 321 arranged in contact with the core 11 and a second cladding layer 322 arranged closer to an outer periphery of the POF 30 than the first cladding layer 321 is formed. In the POF 30, the coating layer 21 is in contact with the second cladding layer 322. In the Fig.3, the shell 32 has a two-layer structure; however, the number of layers in the shell 32 is not limited to two, and three or more layers may be included. (POF manufacturing process)

[0085] The POF of the present embodiment is manufactured, for example, by melt spinning. That is, an example of the manufacturing method of the POF of the present embodiment includes: Producing a fibrous extrusion molded article by melting a core material and extruding the molten core material into a fibrous shape, wherein the fibrous extrusion molded article is produced from the core material, and Producing a laminated body by melting a sheath material and extruding the molten sheath material to coat a surface of the extrusion molded body, wherein the laminated body includes the core material and the sheath material concentrically layered. The above core material includes, for example, the first resin. The above sheath material includes, for example, the second resin.

[0086] If in Fig. 2 is produced, the above manufacturing method may further include drawing the above laminated body while heating at a given temperature to spin the laminated body.

[0087] If the Fig.When manufacturing the POF 30 shown in Fig. 3, for example, a material (first cladding material) for forming the first cladding layer 321 and a material (second cladding material) for forming the second cladding layer 322 are prepared as a cladding material. When the laminated body including the core material and the cladding material concentrically laminated is manufactured by the above manufacturing method, the first cladding material may be melted and extruded to coat the surface of the fibrous extrusion molded body made of the core material, and the second cladding material may be extruded to coat a surface of the first cladding material, so that a laminated body including the core material, the first cladding material, and the second cladding material concentrically laminated is manufactured.

[0088] Fig.4 is a schematic cross-sectional view showing an example of a manufacturing apparatus used to manufacture the Fig. 2 shown POF 20 can be used.

[0089] One in Fig. The apparatus 100 shown in Figure 4 includes a first extrusion device 101a for core formation, a second extrusion device 101b for shell formation, and a third extrusion device 101c for reinforcement layer formation. The apparatus 100 further includes a first chamber 110 and a second chamber 120. The first chamber 110 and the second chamber 120 are arranged vertically in this order from top to bottom.

[0090] The first extrusion device 101a includes a first holding section 102a that holds the core material 1a, and a first extrusion section 103a that extrudes the core material held in the first holding section 102a from the first holding section 102a. The first extrusion device 101a may be further equipped with a heating unit (not shown) such as a heater so that the core material 1a is melted in the first holding section 102a, and the molten core material 1a can be maintained in a molten state until it is molded. In this case, the core material (preform) 1a can be melted in a rod shape by inserting it into the first holding section 102a via an upper opening portion of the first holding section 102a and then heating it in the first holding section 102a.

[0091] In the first extrusion device 101a, the core material 1a is extruded from the first holding section 102a through the first extrusion section 103a, for example, by gas extrusion, to form a core 2. The core material 1a extruded through the first extrusion section 103a to form the core 2 then moves vertically downward to be supplied to the first chamber 110 and the second chamber 120 in this order.

[0092] A second extrusion device 101b includes a second holding section 102b that holds a sheath material 1b, and a second extrusion section 103b that extrudes the sheath material 1b held in the second holding section 102b from the second holding section 102b. The second extrusion device 101b extrudes the sheath material 1b in a molten state to coat an outer periphery of the core 2 made from the core material 1a extruded from the first extrusion device 102a. Specifically, the sheath material 1b extruded from the second extrusion device 101b is supplied to the first chamber 110. In the first chamber 110, a sheath 3 that coats the outer periphery of the core 2 can be formed by coating the core 2 made of the core material 1a with the sheath material 1b.A laminated body of the core 2 and the cladding 3, which coats the outer periphery of the core 2, moves from the first chamber 110 to the second chamber 120.

[0093] The third extrusion device 101c includes, for example, a third holding section 102c that holds a reinforcing layer material 1c, a screw 104 disposed in the third holding section 102c, and a hopper 105 connected to the third holding section 102c. In the third extrusion device 101c, the reinforcing layer material 1c, for example, in pellet form, is fed to the third holding section 102c via the hopper 105. The reinforcing layer material 1c fed to the third holding section 102c becomes soft and flowable by being kneaded by the screws 104 under heating, for example. The softened reinforcing layer material 1c is extruded from the third holding section 102c by the screw 104.

[0094] The reinforcing layer material 1c extruded from the third extrusion device 101c is supplied to the second chamber 120. A reinforcing layer 4 coating the outer periphery of the shell 3 can be formed in the second chamber 120 by coating a surface of the composite body of the core 2 and the shell 3 with the reinforcing layer material 1c.

[0095] A laminated body 5, which concentrically encloses the core 2, the cladding 3, and the reinforcement layer 4, moves from the second chamber 120 to a diffusion tube 130 arranged vertically below the second chamber 120. For example, a heater (not shown) for heating the laminated body can be arranged in the diffusion tube 130. The diffusion tube 130 can diffuse a dopant, such as a refractive index modifier, into the laminated body, with the dopant passing through the diffusion tube 130 while enclosed in the laminated body 5. Regarding the diffusion tube 130, for example, the time required for the laminated body 5 to pass through the diffusion tube 130, the length of the diffusion tube 130, the rotation speed, the temperature, etc. are adjusted as needed, so that the transmission band of the finally obtained POF 20 will be 30 MHz·km or more and 600 MHz·km or less.

[0096] The diffusion tube 130 communicates with an internal flow path of the nozzle 140. That is, a lower opening portion of the diffusion tube 130 communicates with an inlet of the nozzle 140, and the laminated body 5 that has passed through the diffusion tube 130 flows into the internal flow path via the inlet of the nozzle 140. The laminated body 5 passes through the internal flow path so that the diameter is reduced and is then ejected in a fiber shape through an outlet of the nozzle 140.

[0097] The positions of the second chamber 120 and the diffusion tube 130 can be interchanged. That is, the device may have a configuration in which the diffusion tube 130 is disposed below the first chamber 110, the second chamber 120 is disposed below the diffusion tube 130, and the nozzle 140 is installed below the second chamber.

[0098] The laminated body 5, which is ejected in a fiber form through the outlet of the nozzle 140, flows, for example, into an inner space 151 of a cooling tube 150. The laminated body 5 is cooled while passing through the inner space 151. The laminated body 5 is then ejected from the cooling tube 150 through an opening portion. The laminated body 5 ejected from the cooling tube 150 passes, for example, through two rollers 161 and 162 of a pressure roller 160 and then along guide rollers 163 to 165 and is wound as the POF 20 around a winding roller 166. A displacement counter 170 for measuring the outer diameter of the POF 20 may also be provided near the winding roller 166, such as between the guide roller 165 and the winding roller 166.

[0099] The manufacturing apparatus 100 configured to manufacture the POF 20 is taken as an example for detailed description herein. However, the manufacturing apparatus 100 can also be used to manufacture the POF 10.

[0100] When the POF 10 is manufactured using the manufacturing apparatus 100, the third extrusion apparatus 101c for reinforcing layer formation should remain unused.

[0101] When manufacturing the POF 30, another extrusion device should be added between the second extrusion device 101b and the third extrusion device 101c of the manufacturing device 100. For example, the added extrusion device may have the same configuration as that of the second extrusion device 101b. In this case, the second extrusion device 101b should be used to form the first cladding layer 321, and the newly added extrusion device would be used to form the second cladding layer 322. Furthermore, in the above case, a third chamber for forming the second cladding layer 322 is provided between the first chamber 110 and the second chamber 120.That is, the cladding 3 (corresponding to the first cladding layer) coating the outer periphery of the core 2 is formed by coating the core 2 made of the core material 1a with the core material 1b (first cladding material) inside the first chamber 110. The laminated body composed of the core 2 and the cladding 3 (corresponding to the first cladding layer) coating the outer periphery of the core 2 moves from the first chamber 110 to the third chamber, and in the third chamber, an outer periphery of the laminated body is coated with the second cladding material extruded from the extrusion device to form the second cladding layer 322.The laminated body composed of the core 2, the cladding 3 (corresponding to the first cladding layer) coating the outer periphery of the core, and the second cladding layer coating the outer periphery of the cladding 3 moves from the third chamber to the second chamber 120, and a coating layer is formed in the second chamber 120. EXAMPLES

[0102] Below, the present disclosure will be described in more detail with reference to examples and comparative examples. However, the present disclosure is not limited to these. (Example 1)[Preparation of the first fluorine-containing resin and second fluorine-containing resin]

[0103] A polymer of perfluoro-4-methyl-2-methylene-1,3-dioxolane (PFMMD, the compound represented by the above formula (M2)) was prepared as the first fluorine-containing resin and the second fluorine-containing resin. The perfluoro-4-methyl-2-methylene-1,3-dioxolane was synthesized by synthesizing 2-carbomethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane, fluorinating the 2-carbomethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane, and then decarboxylating the resulting carboxylic acid salt. In the polymerization of perfluoro-4-methyl-2-methylene-1,3-dioxolane, perfluorobenzoyl peroxide was used as the polymerization initiator.

[0104] The synthesis of 2-carbomethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane, the fluorination of 2-carbomethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane, the synthesis of perfluoro-4-methyl-2-methylene-1,3-dioxolane, and the polymerization of perfluoro-4-methyl-2-methylene-1,3-dioxolane are described in more detail below. <Synthese von 2-Carbomethyl-2-trifluormethyl-4-methyl-1,3-dioxolan>

[0105] A 3-liter three-necked flask equipped with a water cooler, a thermometer, a magnetic stirrer, and a pressure-equalizing dropping funnel was prepared. A mixture of 2-chloro-1-propanol and 1-chloro-2-propanol (139.4 g, a total of 1.4 mol) of 2-chloro-1-propanol was added to the flask. The flask was cooled to 0°C, methyl trifluoropyruvate was slowly added, and the contents were stirred for 2 hours. A mixture of 100 ml of dimethyl sulfoxide (DMSO) and 194 g of potassium carbonate were added over 1 hour, and the contents were stirred for 8 hours to obtain a reaction mixture. The resulting reaction mixture was mixed with 1 L of water, and an aqueous phase of the resulting mixture was separated. After extraction with dichloromethylene, the dichloromethylene solution was mixed with the organic phase of the reaction mixture. The resulting solution was dried over magnesium sulfate.After removal of the solvent, 245.5 g of crude product was obtained. This crude product was fractionated under reduced pressure (12 Torr) to obtain 230.9 g of purified product, 2-carbomethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane. The boiling point of the purified product was 77 to 78°C, and the percent yield was 77%. HNMR and . 19 F-NMR was used to confirm that the obtained purified product was 2-carbomethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane.

[0106] HNMR (ppm): 4.2 to 4.6, 3.8 to 3.6 (CHCH2, multiplet, 3H), 3.85 to 3.88 (COOCH3, multiplet, 3H), 1.36 to 1.43 (CCH3, multiplet, 3H) 19 F-NMR (ppm): -81.3 (CF3, s, 3F) <Fluorierung von 2-Carbomethyl-2-trifluormethyl-4-methyl-1,3-dioxolan>

[0107] A 4 L amount of 1,1,2-trichlorotrifluoroethane was introduced into a 10 L stirred reaction vessel. Nitrogen and fluorine were flowed into the stirred reaction vessel at a flow rate of 1,340 cc / min and 580 cc / min, respectively, to create a nitrogen-fluorine atmosphere. Five minutes later, 290 g of the previously prepared 2-carbomethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane was dissolved in 750 mL of a 1,1,2-trichlorotrifluoroethane solution, which was then added to the reaction vessel at 0.5 mL / min. The reaction vessel was cooled to 0°C. After the dioxolane was completely added over 24 hours, the fluorine gas flow was stopped. The nitrogen gas was purged, and then an aqueous potassium hydroxide solution was added until the mixture became weakly alkaline.

[0108] After removing a volatile substance under reduced pressure, the reaction vessel was cooled. Cooling was followed by drying under reduced pressure at 70°C for 48 hours to obtain a solid reaction product. The solid reaction product was dissolved in 500 ml of water, to which an excess amount of hydrochloric acid was added to separate the mixture into an organic phase and an aqueous phase. The organic phase was separated and distilled under reduced pressure to obtain perfluoro-2,4-dimethyl-1,3-dioxolane-2-carboxylic acid. The boiling point of the main distillate was 103°C–106°C / 100 mmHg. The percentage yield of fluorination was 85%. <Synthese von Perfluor-4-methyl-2-methylen-1,3-dioxolan>

[0109] The above distillate was neutralized with an aqueous potassium hydroxide solution to obtain perfluoro-4-methyl-2-methylene-1,3-dioxolane. This potassium salt was vacuum-dried at 70°C for one day. The salt decomposed at 250°C to 280°C under a nitrogen or argon atmosphere. By condensation in a cold trap cooled at -78°C, perfluoro-4-methyl-2-methylene-1,3-dioxolane was obtained with a percentage yield of 82%. The boiling point of the product was 45°C / 760 mmHg. The product was purified by 19 Identified by F-NMR and GC-MS.

[0110] 19 F-NMR: -84 ppm (3F, CF3), -129 ppm (2F, =CF2) GC-MS: m / e244 (molecular ion) 225, 197, 169, 150, 131, 100, 75, 50. <Polymerisation von Perfluor-4-methyl-2-methylen-1,3-dioxolan>

[0111] A quantity of 100 g of the perfluoro-4-methyl-2-methylene-1,3-dioxolane obtained above and 1 g of perfluorobenzoyl peroxide were placed in a glass tube, which was then sealed. After oxygen in the system was removed by freeze-thaw pumping cycles, the glass tube was filled with argon and then heated at 50°C for several hours. The contents thereby became solids, which were further heated at 70°C overnight to obtain 100 g of a transparent adhesion.

[0112] The resulting transparent adhesion was dissolved in Fluorinert FC-75 (manufactured by Sumitomo 3M), and the resulting solution was cast onto a glass plate to obtain a thin polymer film. The polymer exhibited a glass transition temperature of 117°C and was completely amorphous. The transparent adhesion was dissolved in a hexafluorobenzene solution, to which chloroform was added for precipitation. The product was thus purified. A polymer resulting from the purification had a glass transition temperature of approximately 131°C. This polymer was used as the first fluorine-containing resin and the second fluorine-containing resin. [Refractive index modifier]

[0113] A chlorotrifluoroethylene oligomer (molecular weight: 585) was used as a refractive index modifier. Specifically, only one component was used, which was obtained by distillation of DAIFLOIL #10, manufactured by DAIKIN INDUSTRIES, LTD., and had a molecular weight of 585. [Core material]

[0114] The first fluorine-containing resin prepared in the above manner was dissolved in Vertrel XF-UP (manufactured by Chemours-Mitsui Fluoroproducts Co., Ltd.) as a solvent. The solution was filtered through an "LPJ-CTA-001-N3" filter (manufactured by ROKI TECHNO CO., LTD.) with a pore diameter of 100 nm, and the filtrate was dropped onto a Hastelloy container heated at 260°C to evaporate the solvent to dryness. The filtered first fluorine-containing resin obtained by drying and the above refractive index modifier were melted and mixed at 260°C to prepare a resin composition. The refractive index modifier concentration in the resin composition was 12 mass%. This resin composition was used as the core material. [First sheath material]

[0115] The second fluorine-containing resin prepared in the above manner was filtered in the same manner as the first fluorine-containing resin in the preparation of the core material, thus obtaining a filtered second fluorine-containing resin. This filtered second fluorine-containing resin was used as the first cladding material to form a first cladding layer. [Second sheath material]

[0116] Teflon AF1600 (manufactured by Chemours-Mitsui Fluoroproducts Co., Ltd.), serving as a fluororesin, and Fomblin YR (manufactured by Solvay SA), serving as a viscosity modifier, were dissolved in Vertrel XF-UP (manufactured by Chemours-Mitsui Fluoroproducts Co., Ltd.) serving as a solvent. The mixing ratio of Teflon AF1600 and Fomblin YR was 7:3 by mass. The resulting solution was filtered through a filter "LPA-SLF-003-N2" (manufactured by ROKI TECHNO CO., LTD.) with a pore diameter of 300 nm, and the filtrate was dropped onto a Hastelloy container heated at 260°C to evaporate the solvent to dryness. The resin composition obtained by drying was used as the second sheath material. [Reinforcing layer material]

[0117] Xylex (manufactured by SABIC Innovative Plastics, glass transition temperature: 113°C) was used as the reinforcement layer material. [POF]

[0118] The POF with the same configuration as the one in Fig. The POF 30 shown in Figure 3 was manufactured by melt spinning using the core material, the first cladding material, the second cladding material, and the reinforcing layer material prepared in the above manner. For the production of the POF, a manufacturing device including the Fig.4 and another extrusion device for second cladding layer formation, which was added between the second extrusion device 101b and the third extrusion device 101c in the manufacturing device 100, were used. The added extrusion device had the same configuration as that of the second extrusion device 101b. That is, in the present example, the second extrusion device 101b was used to form the first cladding layer 321, and the added extrusion device was used to form the second cladding layer 322. The third chamber for forming the second cladding layer 322 was located between the first chamber 110 and the second chamber 120.

[0119] The core material had a melting temperature of 250°C, the first cladding material had a melting temperature of 255°C, the second cladding material had a melting temperature of 260°C, and the reinforcement layer material had a melting temperature of 240°C. The temperature of the diffusion tube 130 was set to 260°C. The drawing temperature of a composite body composed of the core, the cladding (the first and second cladding layers), and the reinforcement layer was 240°C.

[0120] Melt extrusion was performed, with the volumetric rates of the ejected materials being 1.5 for the first cladding material, 1.5 for the second cladding material, and 50 for the reinforcement layer material relative to 1 for the core material. The diffusion time, i.e., the time required for the composite to pass through the diffusion tube 130, was 960 seconds.

[0121] For the resulting POF, the core diameter was 49 µm, and the outer diameter of the reinforcement layer (namely, the outer diameter of the POF) was 235 µm. The core diameter was measured using the following method. [Evaluation of the core diameter]

[0122] The core diameter was measured using an NFP method, which is one of the methods specified in IEC 60793-1-20 and IEC 60793-2-40 subcategory A4h, using light with a wavelength of 850 nm. A 6 m long POF was fabricated, and LED light with a wavelength of 850 nm was incident on one end portion of the POF. The light intensity distribution of the output light at a distance of 6 m was measured, and then a diameter at which the light intensity was 5% was determined. [Evaluation of the numerical aperture (NA)]

[0123] The NA was measured using a far-field pattern (FFP) method, which is one of the methods according to IEC 60793-1-43 and IEC 60793-2-40 subcategory A4h, using light with a wavelength of 850 nm. A 6 m long POF was fabricated, and LED light with a wavelength of 850 nm was incident on one end portion of the POF. A light intensity distribution at angular positions of the output light was measured at a distance of 6 m, and then the NA was calculated. [Evaluation of transmission loss]

[0124] The transmission loss was measured using a cut-back method, which is one of the methods specified in IEC 60793-1-40. A 40 m long POF was fabricated, and an 850 nm LED light was incident on one end of the POF. The output light intensity was measured using a power meter. The POF was shortened by one meter at a time, and the light intensity was measured for each length of the POF. The transmission loss was determined from the change in light intensity. [Evaluation of the volume]

[0125] The band was measured using a pulse method, which is one of the methods specified in IEC 60793-1-41. A 20-m-long POF was manufactured. An optical pulse was incident on one end portion of the POF, and an optical pulse of the output light at a distance of 20 m was measured. After that, the POF was cut to a length of 2 m. In the same way, an optical pulse was incident on it, and an output pulse was measured. For the two output pulses, a transfer function was determined by the Fourier transform specified in IEC 60793-1-41, and a frequency at an optical power of -3 dB was determined. [Evaluation of the M 2 -value]

[0126] The M 2-value was evaluated by the same method as that described in JP 2019-049658 A. That is, a beam radius W (Dσ4) and a beam divergence θ (half angle), defined using a second moment, were determined by the same method as that described in paragraph 0088 of JP 2019-049658 A using a measuring system according to the method described in Fig. 3 of JP 2019-049658 A for NFP and FFP. The results were used to determine the M 2 -value is used by the following mathematical formula (1). Mathematical formula (1): M 2 = πWθ / λ [BER evaluation]

[0127] The BER was evaluated by the same method as described in JP 2019-049658 A. That is, the BER was evaluated by the same method as described in paragraph 0089 of JP 2019-049658 A using a measurement system according to the method described in Fig. 4 of JP 2019-049658 A illustrated. (Example 2)

[0128] A POF was fabricated in the same manner as in Example 1 except for the following points. • In the manufacture of POF, melt extrusion was performed, with the volume rates of the ejected materials being 1.5 for the first cladding material, 1.5 for the second cladding material, and 90 for the reinforcing layer material with respect to 1 for the core material. • The length of the diffusion tube and the rotation speed were adjusted so that the time required for the composite to pass through the diffusion tube was 130 1,000 seconds.

[0129] For the resulting POF, the core diameter, measured in the same manner as in Example 1, was 79 µm, and the outer diameter of the reinforcement layer (namely, the outer diameter of the POF) was 490 µm. The POF was evaluated for its properties in the same manner as in Example 1. (Example 3)

[0130] A POF with the same configuration as the one in Fig. The POF 20 shown in Figure 2 was manufactured. That is, in Example 3, a POF including a single-layer composite cladding was manufactured. The first cladding material of Example 1 was used as a cladding material, and the second cladding material was not used. Differences between Example 3 and Example 1 are shown below. Except for the following points, the POF of Example 3 was manufactured in the same manner as in Example 1. In the obtained POF, the core diameter measured in the same manner as in Example 1 was 44 μm, and the outer diameter of the reinforcing layer (namely, the outer diameter of the POF) was 235 μm. The POF was evaluated for properties in the same manner as in Example 1. Differences to Example 1 • In the preparation of the core material, the filtration of the first fluorine-containing resin was carried out such that the solution of the first fluorine-containing resin was filtered twice through a filter “LPJ-CTA-001-N3” (manufactured by ROK TECHNO CO., LTD.) with a pore diameter of 100 nm and then through a filter “DFA 1ANDESW44” (manufactured by Pall Corporation) with a pore diameter of 40 nm. • The refractive index modifier was filtered through a filter “DFA 1ANDESW44” (manufactured by Pall Corporation) with a pore diameter of 40 nm. • In the manufacture of POF, the second cladding material was not used and no second cladding layer was formed. • The volume rates of the excluded materials were 1.5 for the first cladding material and 53 for the reinforcement layer material relative to 1 for the core material. (Example 4)

[0131] A POF was fabricated in the same manner as in Example 1 except for the following points. • During the preparation of the core material, the refractive index modifier to be added was filtered through a filter “DFA 1ANDESW44” (manufactured by Pall Corporation) with a pore diameter of 40 nm. • The length of the diffusion tube and the rotation speed were adjusted so that the time required for the composite to pass through the diffusion tube was 130 480 seconds.

[0132] For the obtained POF, the core diameter measured in the same manner as in Example 1 was 50 µm, and the outer diameter of the reinforcement layer (namely, the outer diameter of the POF) was 235 µm. The POF was evaluated for properties in the same manner as in Example 1. (Example 5)

[0133] A POF was fabricated in the same manner as in Example 1 except for the following points. • In the preparation of the core material, the synthesized first fluorine-containing resin was directly melted and mixed with the refractive index modifier by heating at 260°C without being dissolved in the solvent and filtered to prepare a resin composition. • In the preparation of the first sheath material, the synthesized second fluorine-containing resin was directly used as the first sheath material without being dissolved in the solvent and filtered. • The temperature of the diffusion tube 130 was 265°C.

[0134] For the resulting POF, the core diameter measured in the same manner as in Example 1 was 50 µm, and the outer diameter of the reinforcement layer (namely, the outer diameter of the POF) was 235 µm. The POF was evaluated for its properties in the same manner as in Example 1. (Example 6)

[0135] A POF was fabricated in the same manner as in Example 1 except for the following points. • In the preparation of the core material and the first cladding material, the solution of the first fluorine-containing resin and the solution of the second fluorine-containing resin were each filtered twice through a filter “LPJ-CTA-001-N3” (manufactured by ROKI TECHNO CO., LTD.) with a pore diameter of 100 nm and then through a filter “DFA 1ANDESW44” (manufactured by Pall Corporation) with a pore diameter of 40 nm. • The refractive index modifier was filtered through a filter “DFA 1ANDESW44” (manufactured by Pall Corporation) with a pore diameter of 40 nm. • The temperature of the diffusion tube 130 was 265°C. • The length of the diffusion tube and the rotation speed were adjusted so that the time required for the composite to pass through the diffusion tube 130 was 1,440 seconds.

[0136] For the obtained POF, the outer diameter of the core, measured in the same manner as in Example 1, was 48 µm, and the outer diameter of the reinforcement layer (namely, the outer diameter of the POF) was 235 µm. The POF was evaluated for its properties in the same manner as in Example 1. (Comparison example 1)

[0137] "FONTEX 50" manufactured by AGC Inc. was used as the POF of Comparative Example 1. Its properties were evaluated in the same manner as in Example 1. (Comparison example 2)

[0138] A POF was fabricated in the same manner as in Example 1 except for the following points. • During the production of the POF, the temperature of the diffusion tube was 250°C. • The length of the diffusion tube and the rotation speed were adjusted so that the time required for the composite to pass through the diffusion tube was 130 480 seconds.

[0139] For the obtained POF, the outer diameter of the core, measured in the same manner as in Example 1, was 50 µm, and the outer diameter of the reinforcement layer (namely, the outer diameter of the POF) was 235 µm. The POF was evaluated for its properties in the same manner as in Example 1.

[0140] Table 1 presents the evaluation results for the POFs of the examples and comparison examples. [Table 1] Structure of the POF Length [m] Core diameter [µm] N / A Transmission loss [dB / km] Transmission band [MHz · km] M 2 -Value BER e.g. 1 4-layer 10 49 0,222 223 122 5,9 4,36 × 10 -9 2 4-layer 15 79 0,22 219 133 3,2 9,25 × 10 -8 3 3-layer 30 44 0,173 76 555 4,3 4,03 × 10 -10 4 4-layer 10 50 0,225 180 40 2,5 1,35 × 10 -8 5 4-layer 10 50 0,219 441 142 3,5 3,78 × 10 -8 6 4-layer 25 48 0,22 98 180 2,1 8,83 × 10 -8 See example 1 FONTEX 50 15 55 0,23 45 207 1,6 3,11 × 10 -6 2 4-layer 15 50 0,225 222 26 6,9 1,12 × 10 -5

[0141] The POFs of Examples 1 to 6, whose transmission attenuation at a wavelength of 850 nm is 70 dB / km or more and 500 dB / km or less and whose transmission bands at a wavelength of 850 nm are 30 MHz·km or more and 600 MHz·km or less, were capable of achieving a low BER of 1 × 10 -7or less. The BER of the POF of Comparative Example 1, whose transmission loss is less than 70 dB / km, is 3.11 × 10 -6 , which is higher than those of the POFs of Examples 1 to 6. Although the POF of Comparative Example 2, whose transmission band is less than 30 MHz·km, has a M 2 -value of 1.7 or more, the BER of the POF of Comparative Example 2 is 1.12 × 10 -5 , which is higher than those of the POFs of Examples 1 to 6. These results confirm that a POF with a length of 30 m or less and a core diameter of 30 µm or more and 100 µm or less can exhibit improved transmission quality in short-distance signal transmission when a transmission attenuation of 70 dB / km or more and 500 dB / km or less and a transmission band of 30 MHz·km or more and 600 MHz·km or less are satisfied.

[0142] For comparison, a POF manufactured in the same manner as in Example 2 and having a length of 40 m was evaluated for BER; the BER was 2.20 × 10 -2 poor. This demonstrates that the present disclosure provides a technique for effectively solving the problem encountered by a POF with a length of 30 m or less in short-distance signal transmission. INDUSTRIAL APPLICABILITY

[0143] The POF of the present disclosure is suitable for applications such as short-distance signal transmission, for example, in the home. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2019-049658 A [0005, 0035, 0126, 0127] JP 2007-504125 A

[0053] Cited non-patent literature

[0000] JIS K 7121: 1987

[0074]

Claims

[1] Plastic optical fiber comprising: a core and a jacket arranged on an outer circumference of the core, wherein the plastic optical fiber has a length of 30 m or less, the core has a diameter of 30 µm or more and 100 µm or less, a transmission loss at a wavelength of 850 nm is 70 dB / km or more and 500 dB / km or less and a transmission band at a wavelength of 850 nm is 30 MHz·km or more and 600 MHz·km or less. [2] The plastic optical fiber according to claim 1, wherein the plastic optical fiber is a graded index plastic optical fiber. [3] A plastic optical fiber according to claim 1, wherein the core includes a first resin and the first resin is at least one selected from the group consisting of a fully fluorinated resin, a partially fluorinated resin, a partially chlorinated resin, and a partially deuterated resin. [4] The plastic optical fiber according to claim 3, wherein the first resin is at least one selected from the group consisting of the fully fluorinated resin and the partially fluorinated resin. [5] The plastic optical fiber according to claim 4, wherein the first resin includes a fluorine-containing polymer including a structural unit (A) represented by the following formula (1): wherein R ff 1 to R ff 4 each independently represents a fluorine atom, a perfluoroalkyl group having 1 to 7 carbon atoms or a perfluoroalkyl ether group having 1 to 7 carbon atoms and R ff 1 and R ff 2 are optionally linked to form a ring. [6] The plastic optical fiber according to claim 5, wherein the fluorine-containing polymer further includes a structural unit (B) represented by the following formula (2): wherein R 1 to R 3 each independently represents a fluorine atom or a perfluoroalkyl group having 1 to 7 carbon atoms, R 4 represents a perfluoroalkyl group having 1 to 7 carbon atoms, the perfluoroalkyl group optionally has a ring structure, one or some of the fluorine atoms are each optionally substituted by a halogen atom other than a fluorine atom, and one or some of the fluorine atoms in the perfluoroalkyl group are each optionally substituted by a halogen atom other than a fluorine atom. [7] The plastic optical fiber according to claim 5, wherein the fluorine-containing polymer further includes a structural unit (C) represented by the following formula (3): wherein R 5 to R 8each independently represents a fluorine atom or a perfluoroalkyl group having 1 to 7 carbon atoms, the perfluoroalkyl group optionally has a ring structure, one or some of the fluorine atoms are each optionally substituted by a halogen atom other than a fluorine atom, and one or some of the fluorine atoms in the perfluoroalkyl group are each optionally substituted by a halogen atom other than a fluorine atom. [8] The plastic optical fiber according to claim 5, wherein the fluorine-containing polymer further includes a structural unit (D) represented by the following formula (4): wherein Z represents an oxygen atom, a single bond, or -OC(R 19 R 20 )O- represents, R 9 to R 20each independently represents a fluorine atom, a perfluoroalkyl group having 1 to 5 carbon atoms or a perfluoroalkoxy group having 1 to 5 carbon atoms, one or some of the fluorine atoms are each optionally substituted by a halogen atom other than a fluorine atom, one or some of the fluorine atoms in the perfluoroalkyl group are each optionally substituted by a halogen atom other than a fluorine atom, one or some of the fluorine atoms in the perfluoroalkoxy group are each optionally substituted by a halogen atom other than a fluorine atom, s and t are each independently 0 to 5 and s + t is an integer from 1 to 6 or in the case that Z is -OC(R 19 R 20 )O-is, s + t is optionally 0. [9] The plastic optical fiber of claim 3, wherein the core further includes a refractive index modifier. [10] The plastic optical fiber according to claim 1, further comprising a reinforcing layer disposed on an outer periphery of the cladding.

Images