Method and apparatus for producing plastic optical fiber

Abstract

To provide a method for producing a plastic optical fiber provided with a colored layer while suppressing an increase in transmission loss.SOLUTION: A method for producing a plastic optical fiber includes (II) forming a coating film by applying a UV-curable composition containing a coloring agent to the surface of a plastic optical fiber main body, and (III) forming a colored layer by irradiating the coating film with ultraviolet light while applying a tensile stress in the longitudinal direction to the plastic optical fiber main body, wherein, in step (III), the tensile stress σd (MPa) and the ultraviolet energy E (mJ / cm2) satisfy the following relational expressions (1) to (4): σd≤aE2+bE+23 (1), a=10-7Tg12-0.0001Tg1+0.0153 (2), b=-4×10-5Tg12+0.0195Tg1-2.0987 (3), 100≤Tg1≤150 (4), where Tg1 is the glass transition temperature (°C) of a material forming an outermost layer of the plastic optical fiber main body.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method and apparatus for manufacturing a plastic optical fiber. [Background technology]

[0002] A plastic optical fiber (hereinafter referred to as "POF"), for example, comprises a central core as a part for transmitting light and a cladding that covers the 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 resin material of the core in order to keep the light within the core. Furthermore, some POFs have a configuration in which a coating layer is further provided on the outer periphery of the cladding to improve the mechanical strength of the POF.

[0003] Since POF is a product whose main function is to transmit light, it is required to have low transmission loss. For example, Patent Document 1 proposes a technique for solving the problem of high transmission loss caused by cracks occurring in the core and / or clad during stretching when manufacturing a POF that includes a core, clad, and protective functional layer (a layer corresponding to the above-mentioned coating layer). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2014 / 042023 Summary of the Invention [Problem to be solved by the invention]

[0005] In some cases, a colored layer is provided on the surface of a POF to identify the POF in a cable incorporating multiple POFs and to protect the POF. That is, in a POF intended to be made into a cable, a colored layer is provided on the outer periphery of the POF main body, which is composed of the above-mentioned core, cladding, and coating layer.

[0006] However, a POF provided with a colored layer may have a problem of increased transmission loss.

[0007] An object of the present disclosure is to provide a POF manufacturing method and manufacturing apparatus that can manufacture a POF having a colored layer in which an increase in transmission loss is suppressed. [Means for solving the problem]

[0008] Conventionally, technologies for reducing transmission loss in the POF body, including the core, which is the optical transmission section, have been proposed, and POFs with reduced transmission loss have been proposed. However, even when such a POF body with reduced transmission loss is used, forming a colored layer on the POF body results in increased transmission loss. Therefore, the present inventors investigated the relationship between the formation of a colored layer and increased transmission loss (i.e., the occurrence of optical blockages in the POF). When a cross section along the length of the POF was examined with a microscope, multiple cracks were found in the optical transmission region (i.e., the core) of the POF body. Furthermore, when light was passed through the same POF while observing the cross section along the length of the POF, bright spots were found at the locations of the cracks. That is, light scattering was confirmed at the locations corresponding to the cracks in the POF. From this phenomenon, the present inventors determined that the formation of the colored layer caused cracks in the optical transmission region of the POF, resulting in optical blockages. The length direction of the POF is the long axis direction of the POF, that is, the light transmission direction of the POF.

[0009] The present inventors further investigated the cause of cracks occurring in the optical transmission region of a POF due to the formation of a colored layer and found that the heat applied to the POF body when forming the colored layer on its outer periphery is related to the tensile stress applied to the POF body when forming the colored layer. A colored layer is generally formed using an ultraviolet curing reaction. That is, the heat applied to the POF body when forming the colored layer on its outer periphery is heat caused by ultraviolet irradiation and is related to the energy of the irradiated ultraviolet rays. Based on the above findings, the present inventors conducted further research and discovered new conditions for forming a colored layer that suppress an increase in transmission loss due to the formation of the colored layer. As a result, they arrived at the following POF manufacturing method according to a first aspect of the present disclosure and a POF manufacturing apparatus according to a second aspect for carrying out the manufacturing method.

[0010] A method for manufacturing a POF according to the first aspect of the present disclosure includes: A method for manufacturing a POF including a POF body and a colored layer covering the outer periphery of the POF body, The manufacturing method includes: (I) preparing the POF main body; (II) applying an ultraviolet-curable composition containing a colorant to the surface of the POF body to form a coating film; (III) applying a tensile stress in the longitudinal direction to the POF body on which the coating film is formed, and irradiating the coating film with ultraviolet light to harden the coating film, thereby forming the colored layer; Including, In the above (III), the tensile stress σ d (MPa) and the energy E (mJ / cm 2 ) satisfies the following relations (1) to (4). σ d ≦aE 2 +bE+23 …(1) a=10 -7 Tg1 2 -0.0001Tg1+0.0153 …(2) b=-4×10 -5 Tg1 2+0.0195Tg1-2.0987 …(3) 100≦Tg1≦150 …(4) In the above relational expressions (2) to (4), Tg1 is the glass transition temperature (° C.) of the material forming the outermost layer of the POF body.

[0011] The POF manufacturing apparatus according to the second aspect of the present disclosure comprises: A POF manufacturing apparatus for carrying out the POF manufacturing method according to the first aspect, The manufacturing apparatus includes: a coating device that applies the ultraviolet curable composition to the surface of the POF body being transported to form a coating film; a curing device that is disposed downstream of the coating device in the conveying direction of the POF body and applies tensile stress in the longitudinal direction to the POF body on which the coating film is formed, while irradiating the coating film with ultraviolet light to cure the coating film; Equipped with The curing device applies the tensile stress to the POF body and irradiates it with ultraviolet light so as to satisfy the relational expressions (1) to (4). [Effects of the Invention]

[0012] According to the manufacturing method and manufacturing apparatus of the present disclosure, a POF having a colored layer can be manufactured in which an increase in transmission loss is suppressed. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view showing an example of a POF manufactured by a POF manufacturing method according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is a flowchart showing a method for manufacturing a POF according to the first embodiment of the present disclosure. [Figure 3] FIG. 3 is a schematic cross-sectional view showing an example of a manufacturing apparatus that can be used to manufacture the POF body shown in FIG. [Figure 4] FIG. 4 is a schematic diagram showing an example of a POF manufacturing apparatus according to the second embodiment of the present disclosure. [Figure 5] FIG. 5 is a graph showing an approximation (light blocking threshold) of the boundary between the conditions under which no problems occur in light transmission and the conditions under which problems occur in light transmission, which was obtained from the results of a light transmission evaluation performed after applying tensile stress to the POF body and irradiating it with ultraviolet light. [Figure 6] FIG. 6 is a graph showing the results of a light transmission evaluation carried out to determine the loss of the POF of the example. [Figure 7] FIG. 7 is a graph showing the results of a light transmission evaluation carried out to determine the loss of the POF of the comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0014] First Embodiment The method for manufacturing a POF according to the first embodiment of the present disclosure is a method for manufacturing a POF including a POF body and a colored layer that covers the outer periphery of the POF body.

[0015] Fig. 1 is a cross-sectional view showing an example of a POF manufactured by the manufacturing method according to the first embodiment. For example, as shown in Fig. 1, a POF 100 manufactured by the manufacturing method according to the first embodiment includes a POF body 10 and a colored layer 20 that covers the outer periphery of the POF body 10. The POF body 10 includes, for example, a core 11, a cladding 12 arranged around the outer periphery of the core 11, and a coating layer 13 arranged around the outer periphery of the cladding 12. In the example shown in Fig. 1, the coating layer 13 corresponds to the outermost layer of the POF body 10.

[0016] 2 is a flowchart showing the manufacturing method according to the first embodiment. (I) preparing a POF main body (S1); (II) applying a UV-curable composition containing a colorant to the surface of the POF body to form a coating film (S2); (III) applying a tensile stress in the longitudinal direction to the POF body on which the coating film is formed, and irradiating the coating film with ultraviolet light to harden the coating film to form a colored layer (S3); In the above (III), the tensile stress σ d (MPa) and the energy E (mJ / cm 2 ) satisfies the following relations (1) to (4). σ d ≦aE 2 +bE+23 …(1) a=10 -7 Tg1 2 -0.0001Tg1+0.0153 …(2) b=-4×10 -5 Tg1 2 +0.0195Tg1-2.0987 …(3) 100≦Tg1≦150 …(4) In the above relational expressions (2) to (4), Tg1 is the glass transition temperature (°C) of the material forming the outermost layer of the POF body. For example, in the example shown in FIG. 1, Tg1 is the glass transition temperature (°C) of the material forming the coating layer 13. In this specification, the glass transition temperature is the midpoint glass transition temperature (T mg ) means

[0017] Ultraviolet energy E (mJ / cm 2 ) is the amount of ultraviolet light exposure (integrated light amount) to the coating film, that is, the integral of the ultraviolet irradiance and irradiation time of the ultraviolet light irradiated to the coating film. When the ultraviolet irradiance is constant, the ultraviolet energy E can be calculated by multiplying the ultraviolet irradiance by the irradiation time.

[0018] According to the manufacturing method of the first embodiment, even if an ultraviolet-curable composition is applied to the surface of the POF body in the above (II), and then the coating film on the surface of the POF body is irradiated with ultraviolet light while applying a tensile stress in the longitudinal direction of the POF body in the above (III), it is possible to prevent cracks from occurring in the POF body. Therefore, in a POF manufactured by the manufacturing method of the first embodiment, an increase in transmission loss due to the formation of a colored layer is suppressed. More specifically, since the above relational expressions (1) to (4) are satisfied, even if a tensile force is applied to the POF body whose temperature has risen due to ultraviolet light irradiation, the occurrence of cracks in the optical transmission region (i.e., core 11) located inside the POF body due to the elongation of the outermost layer of the POF body is suppressed.

[0019] The above relational expressions (1) to (3) are approximate expressions obtained by preparing a plurality of types of POF bodies each having an outermost layer (e.g., coating layer 13) formed of a material having a glass transition temperature in the range of 100°C or more and 150°C or less, irradiating the POF bodies with ultraviolet light while applying tensile stress to the POF bodies, and then evaluating the light transmission through the POF bodies. For one type of POF body, the energy value of the ultraviolet light and the tensile stress were changed to evaluate the light transmission, and the light transmission success or failure was plotted. The above relational expressions (1) to (3) are the results of obtaining approximate expressions (light interruption thresholds) for the boundary between the condition under which no problem occurs in light transmission and the condition under which a problem occurs in light transmission (i.e., light interruption).

[0020] 1 , when the glass transition temperature (°C) of the material of the core 11 is defined as Tg2, the difference between the glass transition temperature Tg2 of the material of the core 11 and the glass transition temperature (i.e., glass transition temperature Tg1) of the material of the outermost coating layer 13 may be 10°C or more. When the difference between the glass transition temperature Tg2 of the material of the core 11 and the glass transition temperature Tg1 of the material of the outermost layer is 10°C or more, even if a tensile force is applied to the POF body 10 whose temperature has risen due to ultraviolet irradiation, the occurrence of cracks in the core 11 is suppressed. Therefore, even if the difference in glass transition temperature between the material of the core 11 and the material of the outermost layer is large, the increase in transmission loss due to the formation of the colored layer is suppressed by satisfying the relational expressions (1) to (4) in (III) above.

[0021] The glass transition temperature Tg2 of the material of the core 11 may be higher than the glass transition temperature (i.e., the glass transition temperature Tg1) of the material of the outermost coating layer 13. In this case, the temperature of the POF body 10 rises due to the irradiation of ultraviolet light in the above (III), and the temperature of the coating layer 13 reaches the glass transition temperature before that of the core 11, making the coating layer 13 more likely to stretch in the longitudinal direction than the core 11. However, even in such a case, since the above relational expressions (1) to (4) are satisfied in the above (III), it is possible to suppress the occurrence of cracks in the core 11.

[0022] The difference between the glass transition temperature Tg2 of the material of core 11 and the glass transition temperature (i.e., glass transition temperature Tg1) of the material of outermost coating layer 13 may be 10°C or more, and the glass transition temperature Tg2 of the material of core 11 may be higher than the glass transition temperature (i.e., glass transition temperature Tg1) of the material of outermost coating layer 13. Even in such a case, the occurrence of cracks in core 11 can be suppressed by satisfying the relational expressions (1) to (4) in (III) above.

[0023] The above steps (I) to (III) of the manufacturing method according to the first embodiment will be described in detail below.

[0024] [Preparation of the POF body (above (I))] In the above (I), a POF body is prepared. Here, an example in which the POF body 10 shown in Fig. 1 is prepared as the POF body will be described.

[0025] Each component of the POF body 10 will now be described in more detail.

[0026] (Core 11) The core 11 is a region that transmits light. The core 11 is made of a resin material that has a higher refractive index than the cladding 12. With this configuration, light that enters the core 11 is confined within the core 11 by the cladding 12 and propagates within the POF body 10.

[0027] Core 11 includes a first resin. Core 11 may include the first resin as a main component. Here, "core 11 includes the first resin as a main component" means that the component contained in core 11 in the largest amount by mass is the first resin. Core 11 may include 75% by mass or more, 80% by mass or more, or 85% by mass or more of the first resin.

[0028] The core 11 may further contain an additive in addition to the first resin. The additive is, for example, a refractive index adjuster. That is, the core 11 may be formed of a resin composition containing the first resin and an additive such as a refractive index adjuster. As the refractive index adjuster, for example, a known refractive index adjuster used in the material of the core 11 of the POF body 10 may be used. The material of the core 11 may contain an additive other than the refractive index adjuster.

[0029] When the POF body 10 is, for example, a graded index (GI) type, the core 11 has a refractive index profile in which the refractive index varies in the radial direction. Such a refractive index profile can be formed, for example, by adding a refractive index adjuster to the first resin and diffusing (for example, thermally diffusing) the refractive index adjuster in the first resin.

[0030] The first resin contained in the core 11 is not particularly limited as long as it is a resin having high transparency. Examples of the first resin include fluorine-containing resins, acrylic resins such as methyl methacrylate, styrene-based resins, and carbonate-based resins.

[0031] 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. The terms partially fluorinated resin, partially chlorinated resin, and partially deuterated resin refer to resins known in the art as core materials for POFs in which some of the hydrogen atoms in C-H bonds have been substituted with fluorine, chlorine, and deuterium, respectively. The term fully fluorinated resin refers to resins known in the art as core materials for POFs in which all of the hydrogen atoms in C-H bonds have been substituted with fluorine. Examples of resins known in the art as core materials include acrylic resins such as methyl methacrylate, styrene resins, and carbonate resins, as described above. Polymers having an alicyclic structure, such as a polymer having a dioxolane structure, may also be used.

[0032] The first resin is preferably at least one selected from the group consisting of fully fluorinated resins and partially fluorinated resins, that is, the first resin is preferably a fluorine-containing resin.

[0033] The first resin of core 11 is preferably a fluororesin containing a fluoropolymer. Hereinafter, the fluororesin contained in core 11 will be referred to as the first fluororesin, and the fluoropolymer contained in the first fluororesin will be referred to as the first fluoropolymer.

[0034] From the viewpoint of suppressing light absorption due to the stretching energy of C-H bonds, the first fluorine-containing polymer contained in the first fluorine-containing resin preferably contains substantially no hydrogen atoms, and particularly preferably has all hydrogen atoms bonded to carbon atoms substituted with fluorine atoms. That is, the first fluorine-containing polymer preferably contains substantially no hydrogen atoms and is perfluorinated. In this specification, "the fluorine-containing polymer contains substantially no hydrogen atoms" means that the content of hydrogen atoms in the fluorine-containing polymer is 1 mol% or less.

[0035] The first fluorine-containing polymer preferably has a fluorine-containing alicyclic structure. The fluorine-containing alicyclic structure may be contained in the main chain of the fluorine-containing polymer or 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 (6): [ka]

[0036] In formula (6), R ff 1 ~R ff 4 R 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. ff 1 and R ff 2 may be linked to form a ring. "Perfluoro" means that all hydrogen atoms bonded to carbon atoms are substituted with fluorine atoms. In formula (6), 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.

[0037] In formula (6), 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.

[0038] R ff 1 and R ff 2 When these are linked to form a ring, the ring may be a 5-membered ring or a 6-membered ring. Examples of this ring include a perfluorotetrahydrofuran ring, a perfluorocyclopentane ring, and a perfluorocyclohexane ring.

[0039] Specific examples of the structural unit (A) include structural units represented by the following formulas (A1) to (A8). [ka]

[0040] Of the structural units represented by the above formulas (A1) to (A8), the structural unit (A) is preferably the structural unit (A2), ie, the structural unit represented by the following formula (7). [ka]

[0041] The first fluorine-containing polymer may contain one or more types of structural unit (A). In the first fluorine-containing polymer, the content of the structural unit (A) is preferably 20 mol % or more, more preferably 40 mol % or more, based on the total of all structural units. When the structural unit (A) is contained in an amount of 20 mol % or more, the first fluorine-containing polymer tends to have higher heat resistance. When the structural unit (A) is contained in an amount of 40 mol % or more, the first fluorine-containing polymer tends to have higher transparency and high mechanical strength in addition to high heat resistance. In the first fluorine-containing polymer, the content of the structural unit (A) is preferably 95 mol % or less, more preferably 70 mol % or less, based on the total of all structural units.

[0042] The structural unit (A) is derived from, for example, a compound represented by the following formula (8): In formula (8), R ff 1 ~R ff 4 is the same as formula (6). The compound represented by formula (8) can be obtained by a known production method, such as the production method disclosed in JP-A-2007-504125. [ka]

[0043] Specific examples of the compound represented by the above formula (8) include compounds represented by the following formulae (M1) to (M8). [ka]

[0044] The fluorine-containing polymer may further contain other structural units in addition to the structural unit (A). Examples of the other structural units include the following structural units (B) to (D).

[0045] The structural unit (B) is represented by the following formula (9). [ka]

[0046] In formula (9), R 1 ~R 3 R each independently represents a fluorine atom or a perfluoroalkyl group having 1 to 7 carbon atoms. 4 represents a perfluoroalkyl group having 1 to 7 carbon atoms. The perfluoroalkyl group may have a ring structure. Some of the fluorine atoms may be substituted with halogen atoms other than fluorine atoms. Some of the fluorine atoms in the perfluoroalkyl group may be substituted with halogen atoms other than fluorine atoms.

[0047] The fluorine-containing polymer may contain one or more types of structural unit (B). In the fluorine-containing polymer, the content of the structural unit (B) is preferably 5 to 10 mol % based on the total of all structural units. The content of the structural unit (B) may be 9 mol % or less, or may be 8 mol % or less.

[0048] The structural unit (B) is derived from, for example, a compound represented by the following formula (10): 1 ~R 4 is the same as formula (9). The compound represented by formula (10) is a fluorine-containing vinyl ether such as perfluorovinyl ether. [ka]

[0049] The structural unit (C) is represented by the following formula (11). [ka]

[0050] In formula (11), R 5 ~R 8each independently represents a fluorine atom or a perfluoroalkyl group having 1 to 7 carbon atoms. The perfluoroalkyl group may have a ring structure. Some of the fluorine atoms may be substituted with halogen atoms other than fluorine atoms. Some of the fluorine atoms in the perfluoroalkyl group may be substituted with halogen atoms other than fluorine atoms.

[0051] The fluorine-containing polymer may contain one or more types of structural unit (C). In the fluorine-containing polymer, the content of the structural unit (C) is preferably 5 to 10 mol % based on the total of all structural units. The content of the structural unit (C) may be 9 mol % or less, or may be 8 mol % or less.

[0052] The structural unit (C) is derived from, for example, a compound represented by the following formula (12): 5 ~R 8 is the same as formula (11). The compound represented by formula (12) is a fluorine-containing olefin such as tetrafluoroethylene or chlorotrifluoroethylene. [ka]

[0053] The structural unit (D) is represented by the following formula (13). [ka]

[0054] In formula (13), Z is an oxygen atom, a single bond, or —OC(R 19 R 20 )O-, R 9 ~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. Some of the fluorine atoms may be substituted with halogen atoms other than fluorine atoms. Some of the fluorine atoms in the perfluoroalkyl group may be substituted with halogen atoms other than fluorine atoms. Some of the fluorine atoms in the perfluoroalkoxy group may be substituted with halogen atoms other than fluorine atoms. s and t each independently represent an integer of 0 to 5, and s+t is an integer of 1 to 6 (provided that Z is -OC(R 19 R 20 )O-, s+t may be 0).

[0055] The structural unit (D) is preferably represented by the following formula (14): The structural unit represented by the following formula (14) is the structural unit represented by the above formula (13) in which Z is an oxygen atom, s is 0, and t is 2. [ka]

[0056] In formula (14), R 141 , R 142 , 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. Some of the fluorine atoms may be substituted with halogen atoms other than fluorine atoms. Some of the fluorine atoms in the perfluoroalkyl group may be substituted with halogen atoms other than fluorine atoms. Some of the fluorine atoms in the perfluoroalkoxy group may be substituted with halogen atoms other than fluorine atoms.

[0057] The fluorine-containing polymer may contain one or more types of structural unit (D). In the fluorine-containing polymer, the content of the structural unit (D) is preferably 30 to 67 mol% based on the total of all structural units. The content of the structural unit (D) is, for example, 35 mol% or more, and may be 60 mol% or less, or may be 55 mol% or less.

[0058] The structural unit (D) is derived from, for example, a compound represented by the following formula (15): In formula (15), Z, R 9 ~R 18 , s and t are the same as in formula (13). The compound represented by formula (11) is a fluorine-containing compound which has two or more polymerizable double bonds and is capable of cyclopolymerization. [ka]

[0059] The structural unit (D) is preferably derived from a compound represented by the following formula (16): 141 , R 142 , R 151 , and R 152 is the same as equation (14). [ka]

[0060] Specific examples of the compound represented by formula (15) or formula (16) include the following compounds. CF2=CFOCF2CF=CF2 CF2=CFFOCF(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

[0061] The first fluorine-containing polymer may further contain other structural units than the structural units (A) to (D), but preferably does not substantially contain other structural units than the structural units (A) to (D). Here, "the fluorine-containing polymer does not substantially contain other structural units than the structural units (A) to (D)" means that the total of the structural units (A) to (D) is 95 mol % or more, preferably 98 mol % or more, of the total of all structural units in the fluorine-containing polymer.

[0062] The polymerization method for the first fluorine-containing polymer is not particularly limited, and for example, a general polymerization method such as radical polymerization can be used. The polymerization initiator for polymerizing the fluorine-containing polymer may be a perfluorinated compound.

[0063] The first fluorine-containing polymer constitutes a first fluorine-containing resin used as the first resin. The first resin has a first glass transition temperature of, for example, more than 105°C and not more than 140°C, and may be 120°C or higher.

[0064] (Clad 12) In the POF body 10 of this embodiment, the clad 12 contains, for example, a second resin. The clad 12 may contain the second resin as a main component. Here, the clad 12 containing the second resin as a main component means that the component contained in the clad 12 in the largest amount by mass ratio is the second resin. The clad 12 may contain 80% by mass or more of the second resin, 90% by mass or more, or 95% by mass or more of the second resin. The clad 12 may be made only of the second resin. The clad 12 may further contain an additive in addition to the second resin.

[0065] The second resin contained in the clad 12 is not particularly limited as long as it is a resin having high transparency. Examples of the second resin are the same as those exemplified as the resin that can be used as the first resin. As with the first resin, a fluorine-containing resin is preferably used as the second resin.

[0066] The second resin of the clad 12 is preferably a fluororesin containing a fluoropolymer. Hereinafter, the fluororesin contained in the clad 12 will be referred to as the second fluororesin, and the fluoropolymer contained in the second fluororesin will be referred to as the second fluoropolymer.

[0067] As the second fluorine-containing resin, those exemplified as the fluorine-containing resin that can be used as the first fluorine-containing resin can be used.

[0068] As the second fluorine-containing resin, a fluorine-containing resin containing a fluorine-containing polymer having an amorphous structure and further containing a constituent unit (E) represented by the following formula (17), and a fluorine-containing plasticizer may be used. [ka] (In formula (17), Z is an oxygen atom, a single bond, or —OC(R 31 R 32 )O-, R 21 ~R 32 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. "Perfluoro" means that all hydrogen atoms bonded to carbon atoms have been substituted with fluorine atoms. Some of the fluorine atoms may be substituted with halogen atoms other than fluorine atoms. Some of the fluorine atoms in the perfluoroalkyl group may be substituted with halogen atoms other than fluorine atoms. Some of the fluorine atoms in the perfluoroalkoxy group may be substituted with halogen atoms other than fluorine atoms. s and t each independently represent an integer of 0 to 5, and s+t is an integer of 1 to 6 (provided that Z is not -OC(R 31 R 32) In the case of O-, s+t may be 0. u and v are each independently 0 or 1.

[0069] The fluorine-containing polymer containing the structural unit (E) may further contain a structural unit (F) represented by the following formula (18). [ka] (In formula (18), R 33 ~R 36 each independently represents a fluorine atom or a perfluoroalkyl group having 1 to 7 carbon atoms. The perfluoroalkyl group may have a ring structure. Some of the fluorine atoms may be substituted with halogen atoms other than fluorine atoms. Some of the fluorine atoms in the perfluoroalkyl group may be substituted with halogen atoms other than fluorine atoms.

[0070] When the second fluorine-containing polymer is the above copolymer, the ratio of the structural unit (E) to the structural unit (F) is optional and is not particularly limited.

[0071] The second fluorine-containing polymer is preferably, for example, at least one selected from the group consisting of fluorine-containing polymer A and fluorine-containing polymer B shown below.

[0072] The fluorine-containing polymer A contains a structural unit (G) represented by the following formula (19) and a structural unit (H) represented by the following formula (20). 23 , R 24 , R 31 , and R 32 is the same as the above equation (17).

[0073] [ka] [ka] (In formula (20), R 37 ~R 40each independently represents a fluorine atom or a perfluoroalkyl group having 1 to 7 carbon atoms. The perfluoroalkyl group may have a ring structure. Some of the fluorine atoms may be substituted with halogen atoms other than fluorine atoms. Some of the fluorine atoms in the perfluoroalkyl group may be substituted with halogen atoms other than fluorine atoms.

[0074] The fluorine-containing polymer B contains a structural unit (I) represented by the following formula (21): 21 ~R 24 , R 27 ~R 30 , R 31 , and R 32 is the same as the above equation (17). [ka]

[0075] The above-mentioned fluorine-containing polymer A and fluorine-containing polymer B have very high transparency and can have a refractive index that is very low compared with the general refractive index of the first fluorine-containing resin used as the material for the core 11. Therefore, the second fluorine-containing resin containing at least one selected from the group consisting of fluorine-containing polymer A and fluorine-containing polymer B as the second fluorine-containing polymer can further reduce the refractive index while maintaining the high transparency of the cladding 12. As a result, the difference between the refractive index of the core 11 and the refractive index of the cladding 12 can be made even larger, which further improves the effect of confining light in the core 11 by the cladding 12 and makes it easier to achieve low transmission loss in the POF main body 10.

[0076] The second fluorine-containing polymer preferably contains a structural unit (J) represented by the following formula (22). [ka] (In formula (22), m and n are any integers.)

[0077] The fluorine-containing plasticizer is preferably a fluorine-containing polyether, more preferably a perfluoropolyether.

[0078] Specific examples of perfluoropolyethers include organic compounds represented by the following formula (23) or (24): In the following formulas (23) and (24), p1, q1, p2, and q2 each represent an arbitrary integer. CF3-[(O(CF3)CFCF2) p1 -(OCF2) q1 ]OCF3(23) CF3-[(OCF2CF2) p2 -(OCF2) q2 ]OCF3(24)

[0079] The second fluorine-containing polymer constitutes a second fluorine-containing resin used as the second resin. The second glass transition temperature Tg2 of the second resin is not particularly limited and may be, for example, higher than 105°C and 170°C or lower, or 125°C or higher.

[0080] (Coating layer 13) The reinforcing layer 13 is provided to improve the mechanical strength of the POF body 10. For example, the material and configuration used for reinforcing layers in known POFs can be applied to the reinforcing layer 13. However, when the reinforcing layer 13 is the outermost layer of the POF body 10, the material forming the reinforcing layer 13 has a glass transition temperature in the range of 100°C or higher and 150°C or lower.

[0081] Examples of materials for the reinforcing layer 13 include various engineering plastics such as polycarbonate resin, polyester, cycloolefin polymer, cycloolefin copolymer, polytetrafluoroethylene (PTFE), modified PTFE, and tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA), or copolymers or mixtures thereof.

[0082] The reinforcing layer 13 preferably contains a polycarbonate resin, which allows the reinforcing layer 13 to have excellent heat resistance and transparency.

[0083] The thickness of the coating layer 13 is preferably, for example, 50 μm or more and 250 μm or less. When the thickness of the coating layer 13 is 50 μm or more, the core 11 and the cladding 12 can be sufficiently protected by the coating layer 13, thereby obtaining a highly reliable POF body 10. When the thickness of the coating layer 13 is 250 μm or less, a highly flexible POF body 10 can be obtained.

[0084] (POF main body manufacturing method) The POF body 10 is manufactured by using, for example, a melt spinning method. melting a core material and extruding it into a fiber shape to produce a fiber-shaped molded body made of the core material; melting a clad material and extruding it to cover the surface of the molded body, thereby producing a first laminate in which the core material and the clad material are concentrically laminated; a coating layer material is melted and extruded to cover the surface of the first laminate, thereby producing a second laminate in which the core material, the clad material, and the resin composition are concentrically laminated; The composition can be produced by a production method including the steps of:

[0085] The core material includes, for example, a first resin. The clad material includes, for example, a second resin. The coating layer material includes a resin that forms the coating layer. Examples of the first resin, the second resin, and the resin that forms the coating layer are as described above.

[0086] When producing a fiber-shaped molded body made of a core material, a first core material containing a refractive index control agent may be extruded first to form an inner core layer, and then a second core material may be extruded to cover the outer periphery of the inner core layer 2 formed of the first core material. In this case, the refractive index control agent contained in the first core material is diffused toward the outer periphery of the core formed of the second core material, thereby forming a core 11 having a refractive index profile.

[0087] FIG. 3 is a schematic cross-sectional view showing an example of a manufacturing apparatus that can be used to manufacture the POF body 10 shown in FIG.

[0088] The apparatus 1000 shown in FIG. 3 includes a first extrusion device 101a for extruding a first core material, a second extrusion device 101b for extruding a second core material, a third extrusion device 101c for extruding a cladding material, and a fourth extrusion device 101d for forming a coating layer.

[0089] The first extrusion device 101a has a first storage section 102a that stores the first core material 1a and a first extrusion section 103a that extrudes the first core material 1a stored in the first storage section 102a from the first storage section 102a. The first extrusion device 101a is further provided with a heating section (not shown) so that the first core material 1a can be melted in the first storage section 102a and the molten first core material 1a can be maintained in a molten state until it is molded. A rod-shaped first core material (preform) 1a is inserted into the first storage section 102a through an upper opening and is heated and melted in the first storage section 102a.

[0090] In the first extrusion device 101a, the first core material 1a is extruded by gas extrusion from the first storage section 102a through the first extrusion section 103a to form the inner core layer section 2. The first core material 1a extruded through the first extrusion section 103a to form the inner core layer section 2 then moves vertically downward and is supplied to the first chamber 110.

[0091] The second extrusion device 101b has a second storage section 102b that stores the second core material 1b and a second extrusion section 103b that extrudes the second core material 1b stored in the second storage section 102b from the second storage section 102b. The second extrusion device 101b extrudes the molten second core material so as to cover the outer periphery of the inner core layer section 2 formed from the first core material 1a extruded from the first extrusion device 101a. Specifically, the second core material extruded from the second extrusion device 101b is supplied to a first chamber 110. In the first chamber 110, the inner core layer section 2 formed from the first core material 1a is covered with the second core material, thereby forming an outer core section 3 that covers the outer periphery of the inner core layer section 2. The laminate 4 formed of the inner core layer portion 2 and the outer core portion 3 covering the outer periphery of the inner core layer portion 2 moves from the first chamber 110 to the diffusion tube 120 arranged vertically below the first chamber 110. A heater (not shown) for heating the laminate is arranged in the diffusion tube 120. The diffusion tube 120 diffuses the refractive index adjuster and the like contained in the inner core layer portion 2 of the laminate 4 passing through the inside of the diffusion tube 120 toward the outer core portion 3. In other words, the inner core layer portion 2 and the outer core portion 3 ultimately form a core.

[0092] The third extrusion device 101c has a third housing section 102c that houses the clad material 1c and a third extrusion section 103c that extrudes the clad material 1c housed in the third housing section 102c from the third housing section 102c. The third extrusion device 101c extrudes the molten clad material 1c so as to coat the outer periphery of the laminate 4 that has passed through the diffusion tube 120. Specifically, the clad material 1c extruded from the third extrusion device 101c is supplied to a second chamber 130. In the second chamber 130, the laminate 4 (i.e., the core) is coated with the clad material 1c, thereby forming a clad 5 that covers the outer periphery of the core. Hereinafter, the laminate 4 will be referred to as the core 4. The laminate formed of the core 4 and the clad 5 moves from the second chamber 130 to a third chamber 140 located vertically below the second chamber 130.

[0093] The fourth extrusion device 101d includes a fourth storage section 102d that stores the coating layer material 1d, a screw 104 disposed in the fourth storage section 102d, and a hopper 105 connected to the fourth storage section 102d. In the fourth extrusion device 101d, the coating layer material 1d, for example, in pellet form, is supplied to the fourth storage section 102d through the hopper 105. The coating layer material 1d supplied to the fourth storage section 102d is kneaded by the screw 104 while being heated, thereby softening and becoming flowable. The softened coating layer material 1d is extruded from the fourth storage section 102d by the screw 104.

[0094] The coating layer material 1d extruded from the fourth extrusion device 101d is supplied to the third chamber 140. In the third chamber 140, the surface of the first laminate formed of the core 4 and the clad 5 is coated with the coating layer material 1d, thereby forming a coating layer 6 that covers the outer periphery of the clad 5.

[0095] The second laminate 7, in which the core 4, the clad 5, and the coating layer 6 are concentrically laminated, flows from the third chamber 140 into the internal flow path through the inlet of the nozzle 150. The second laminate 7 is reduced in diameter as it passes through the internal flow path, and is discharged from the outlet of the nozzle 150 in the form of a fiber.

[0096] The second laminate 7 discharged in a fiber form from the discharge port of the nozzle 150 flows into the internal space 161 of the cooling pipe 160, is cooled while passing through the internal space 161, and is discharged from the opening to the outside of the cooling pipe 160. The second laminate 7 discharged from the cooling pipe 160 passes between two rolls 171 and 172 of the nip roll 170, and further passes through guide rolls 173 to 175 to be taken up on a take-up roll 176 as a POF 10. A displacement meter 180 for measuring the outer diameter of the POF main body 10 may be further provided near the take-up roll 176, for example, between the guide roll 175 and the take-up roll 176.

[0097] [Application of UV-curable composition containing colorant (above (II))] An ultraviolet-curable composition containing a colorant is applied to the surface of the POF body to form a coating film.

[0098] The ultraviolet-curable composition contains, for example, an ultraviolet-curable multifunctional acrylate and a colorant.

[0099] The colorant is appropriately selected depending on the use and purpose of the POF to be manufactured. Examples of the colorant include pigments and dyes, and preferably pigments. The pigment is not particularly limited, and examples thereof include white pigments, black pigments, yellow pigments, green pigments, red pigments, and blue pigments.

[0100] As the ultraviolet-curable polyfunctional acrylate, one type may be used alone, or multiple types may be used in combination. When one type is used alone as the ultraviolet-curable polyfunctional acrylate, the ultraviolet-curable polyfunctional acrylate has a vinyl group and an aromatic ring group. On the other hand, when multiple types are used in combination as the ultraviolet-curable polyfunctional acrylate, all of the multiple types of ultraviolet-curable polyfunctional acrylates have a vinyl group, or one ultraviolet-curable polyfunctional acrylate has a vinyl group and an aromatic ring group, and the other energy ray-curable polyfunctional acrylate has a vinyl group but does not have an aromatic ring group.

[0101] The blending ratio of each of the above-mentioned raw materials is appropriately set depending on the application and purpose of the POF to be manufactured. The ratio of the ultraviolet-curable polyfunctional acrylate in the ultraviolet-curable composition is, for example, 50 mass% or more, preferably 75 mass% or more, and is, for example, 99 mass% or less. The number of mass parts of the colorant per 100 mass parts of the ultraviolet-curable polyfunctional acrylate is, for example, 1 mass part or more, for example, 25 mass parts or less.

[0102] The ultraviolet-curable composition may further contain a photoinitiator, a photosensitizer, and the like.

[0103] The prepared ultraviolet-curable composition is allowed to contain oxygen, which is derived from the oxygen contained in the air since the ultraviolet-curable composition is prepared in the air.

[0104] As the ultraviolet-curable composition, commercially available products can be used, for example, Optical Fiber Coloring Ink Series (manufactured by Phichem).

[0105] The thickness of the coating film formed by applying the ultraviolet-curable composition is not particularly limited, and may be appropriately set according to the thickness of the colored layer determined depending on the use and purpose of the POF to be manufactured. The thickness of the colored layer 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. The ratio of the thickness of the colored layer to the diameter of the POF body is, for example, 0.0001 or more, preferably 0.001 or more, and, for example, 1 or less, preferably 0.5 or less.

[0106] [Curing of coating film (above (III))] While applying a tensile stress in the longitudinal direction to the POF body on which the coating film is formed, the coating film is irradiated with ultraviolet light to harden the coating film, thereby forming a colored layer. d (MPa) and ultraviolet energy E (mJ / cm 2 ) satisfies the above relational expressions (1) to (4), as described above.

[0107] In order to sufficiently cure the coating film formed from the ultraviolet curable composition, the ultraviolet energy E (mJ / cm 2 ) is 10 mJ / cm 2 More than 15mJ / cm is preferable. 2 More preferably, 20 mJ / cm or more 2 The above is particularly preferable. The energy E (mJ / cm 2 ) is, for example, 50 mJ / cm 2 The following is the result.

[0108] In order to irradiate the coating film with ultraviolet rays uniformly and efficiently, it is preferable that the POF body on which the coating film is formed is introduced into an irradiation chamber, and the irradiation is performed on the coating film on the POF body passing through the irradiation chamber. At this time, the tensile stress σ applied to the POF body is adjusted so that the POF body does not fall off the conveying path and the coating film is irradiated with ultraviolet rays uniformly and efficiently. d (MPa) is preferably 3 MPa or more, and more preferably 5 MPa or more. d (MPa) may be 10 MPa or more. d (MPa) is, for example, 20 MPa or less. In this case, cracks in the POF body can be reduced.

[0109] Second Embodiment A POF manufacturing apparatus according to a second embodiment of the present disclosure is an apparatus for carrying out the manufacturing method according to the first embodiment. The manufacturing apparatus according to the second embodiment includes a coating device and a curing device. The coating device applies an ultraviolet-curable composition to the surface of the POF body being transported to form a coating film. The curing device is arranged downstream of the coating device in the transport direction of the POF body, and applies tensile stress in the longitudinal direction of the POF body on which the coating film has been formed, while irradiating the coating film with ultraviolet light to cure the coating. The curing device applies tensile stress to the POF body and irradiates ultraviolet light so as to satisfy the relational expressions (1) to (4) described in the first embodiment.

[0110] The POF body and the ultraviolet curable composition are the same as those described in the first embodiment, and therefore detailed description thereof will be omitted here.

[0111] According to the manufacturing apparatus of the second embodiment, a POF provided with a colored layer can be manufactured while reducing or suppressing an increase in transmission loss caused by the formation of the colored layer.

[0112] Fig. 4 is a schematic diagram showing an example of a POF manufacturing apparatus according to the second embodiment, in which the manufacturing apparatus is used to manufacture the POF 100 shown in Fig. 1 and described in the first embodiment.

[0113] 4 includes a coating device 210 and a curing device 220. The manufacturing device 200 further includes a payout roll 230 for paying out the POF body 10, a take-up roll 240 for taking up the POF 100, and a predetermined number of guide rolls 250 for guiding the POF body 10 or the POF 100.

[0114] A roll of the POF body 10 is attached to the payout roll 230. The POF body 10 paid out from the payout roll 230 is guided by a predetermined number of guide rolls 250 and transported to the coating device 210.

[0115] In the coating device 210, an ultraviolet-curable composition is applied to the surface of the POF body 10 being conveyed, thereby forming a coating film. A known coating device can be used to apply the ultraviolet-curable composition. As an example, the coating device 210 may include a coating die 211 as shown in FIG. 4. The POF body 10 is passed through the coating die 211, and an ultraviolet-curable composition 212 supplied to the coating die 211 is applied to the outer periphery of the POF body 10, and the POF body 10 on which the coating film has been formed is discharged from the outlet of the coating die 211.

[0116] The POF body 10 on which the coating film has been formed is transported from the coating device 210 to the curing device 220. In the curing device 220, ultraviolet light is irradiated onto the coating film while applying tensile stress in the longitudinal direction to the POF body 10 on which the coating film has been formed, thereby curing the coating film. The curing device 220 includes, for example, a light source 221 for irradiating ultraviolet light and an irradiation chamber 222 arranged opposite the light source 221. The irradiation chamber 222 is configured so that the POF body 10 on which the coating film has been formed can pass through it. The irradiation chamber 221 has a substantially cylindrical shape and is made of a light-transmitting material such as quartz glass. A gas inert to radical polymerization can be introduced into the irradiation chamber 222. Examples of such gases include nitrogen gas, carbon dioxide gas, and helium gas, and nitrogen gas is preferred. The gas flow rate is appropriately set depending on the volume of the irradiation chamber 222 and / or the speed at which the POF body 10 on which the coating film has been formed passes through it. Specifically, the gas flow rate is, for example, 3 L / min or more, preferably 5 L / min or more, more preferably 8 L / min or more, and is, for example, 100 L / min or less.

[0117] The POF 100 on which the coating film is cured in the curing device 220 to form the colored layer 20 is taken up from the curing device 220 by way of a predetermined number of guide rolls 250 onto a take-up roll 240 .

[0118] In the curing device 220, the tensile stress applied to the POF body 10 and the irradiation energy of the ultraviolet light are controlled so as to satisfy the relational expressions (1) to (4) described in the first embodiment. The irradiation energy of the ultraviolet light can be controlled, for example, by the illuminance setting of the light source 221 and the passing speed of the POF body 10 in the irradiation chamber 222 (i.e., the irradiation time). These controls may also be performed by a controller.

[0119] The manufacturing apparatus 200 shown in FIG. 4 is an example, and other devices not shown in FIG. 4 may be incorporated as needed, for example, between the delivery roll 230 and the coating device 210, or between the curing device 220 and the winding roll 240. [Example]

[0120] <Production of the POF main body and determination of relational expressions (1) to (3)> [Production of the first fluorine-containing resin] As the first fluorine-containing resin, a polymer of perfluoro-4-methyl-2-methylene-1,3-dioxolane (PFMMD) was prepared. Perfluoro-4-methyl-2-methylene-1,3-dioxolane was synthesized by first synthesizing 2-carbomethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane, fluorinating this, and decarboxylating and separating the resulting carboxylate. For the polymerization of perfluoro-4-methyl-2-methylene-1,3-dioxolane, perfluorobenzoyl peroxide was used as the polymerization initiator.

[0121] The details of 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 will be described in detail below.

[0122] [Synthesis of 2-carbomethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane] A 3 L three-neck flask equipped with a water-cooled condenser, a thermometer, a magnetic stirrer, and a pressure-equalizing dropping funnel was prepared. 139.4 g (1.4 mol total) of a mixture of 2-chloro-1-propanol and 1-chloro-2-propanol was added to the flask. The flask was cooled to 0 °C, and methyl trifluoropyruvate was slowly added and stirred for an additional 2 hours. 100 mL of dimethyl sulfoxide (DMSO) and 194 g of potassium carbonate were added over 1 hour, followed by stirring for an additional 8 hours to obtain a reaction mixture. The resulting reaction mixture was mixed with 1 L of water, and the aqueous phase was separated. This was then extracted with dichloromethylene. The dichloromethylene solution was mixed with the organic reaction mixture phase, and the resulting solution was dried over magnesium sulfate. After removing the solvent, 245.5 g of crude product was obtained. This crude product was fractionally distilled under reduced pressure (12 Torr) to obtain 230.9 g of purified 2-carbomethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane. The boiling point of the purified product was 77-78°C, and the yield was 77%. The purified product was confirmed to be 2-carbomethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane by HNMR and 19 This was confirmed by FNMR.

[0123] HNMR(ppm):4.2-4.6,3.8-3.6(CHCH2,muliplet,3H),3.85-3.88(COOCH3,multiplet,3H),1.36-1.43(CCH3,multiplet,3H) 19 FNMR(ppm):-81.3(CF3,s,3F)

[0124] <Fluorination of 2-carbomethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane> A 10 L stirred reactor was charged with 4 L of 1,1,2-trichlorotrifluoroethane. Nitrogen was introduced into the stirred reactor at a flow rate of 1340 cc / min, and fluorine was introduced at a flow rate of 580 cc / min, creating 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 1,1,2-trichlorotrifluoroethane solution, and this solution was added to the reactor at a rate of 0.5 mL / min. The reactor was cooled to 0°C. After adding all the dioxolane over 24 hours, the fluorine gas flow was stopped. After purging with nitrogen, an aqueous potassium hydroxide solution was added until the mixture became slightly alkaline.

[0125] After removing volatile materials under reduced pressure, the reaction vessel was cooled to ambient temperature and then dried 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, and excess hydrochloric acid was added to separate the product 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 fluorination yield was 85%.

[0126] <Synthesis of perfluoro-4-methyl-2-methylene-1,3-dioxolane> The distillate was neutralized with aqueous potassium hydroxide to obtain perfluoro-2,4-dimethyl-2-potassium carboxylate-1,3-dioxolane. The potassium salt was vacuum dried at 70°C for 1 day. The salt was decomposed at 250-280°C under a nitrogen or argon atmosphere. Condensation was carried out in a cold trap cooled to -78°C to obtain perfluoro-4-methyl-2-methylene-1,3-dioxolane in 82% yield. The boiling point of the product was 45°C / 760mmHg. 19 The products were identified using FNMR and GC-MS.

[0127] 19 FNMR:-84ppm(3F,CF3),-129ppm(2F,=CF2) GC-MS:m / e244(Molecular ion)225,197,169,150,131,100,75,50.

[0128] <Polymerization of perfluoro-4-methyl-2-methylene-1,3-dioxolane> 100 g of the perfluoro-4-methyl-2-methylene-1,3-dioxolane obtained above and 1 g of perfluorobenzoyl peroxide were sealed in a glass tube. The glass tube was degassed by freeze-degassing, then refilled with argon and heated at 50°C for several hours. The contents became solid, but further heating at 70°C overnight yielded 100 g of a transparent rod.

[0129] The obtained transparent rod-like substance was dissolved in Fluorinert FC-75 (manufactured by Sumitomo 3M), and the obtained solution was poured onto a glass plate to obtain a thin film of the polymer. The obtained polymer had a glass transition temperature of 117°C and was completely amorphous. The transparent rod-like substance was dissolved in hexafluorobenzene, and chloroform was added thereto to cause precipitation, thereby purifying the product. The glass transition temperature of the purified polymer was approximately 131°C. This polymer was designated as the first fluorine-containing resin.

[0130] [Refractive index adjuster] Chlorotrifluoroethylene oligomer (molecular weight 700 to 850) was used as the refractive index adjuster. Specifically, Daikin Industries, Ltd.'s "Dafloil #10" was distilled, and the component with a molecular weight of 700 to 850 was separated. The separated component with a molecular weight of 700 to 850 was filtered through a 40 nm pore size filter "DFA1ANDESW44" (PALL Corporation) to obtain the refractive index adjuster.

[0131] [First core material] The first fluorine-containing resin prepared by the above method was dissolved in a solvent, Vertrel XF-UP (manufactured by Mitsui-Chemours Fluoroproducts). The solution was filtered twice using a 100 nm pore size filter, "LPJ-CTA-001-N3" (manufactured by Roki Techno Corporation), and the filtrate was dropped into a Hastelloy container heated to 260°C to evaporate the solvent and dry the mixture. The filtered fluorine-containing resin obtained by drying and solidifying it and the refractive index modifier were melt-mixed at 260°C to prepare a resin composition. The concentration of the refractive index modifier in the resulting resin composition was 12% by mass. This resin composition was used as the first core material.

[0132] [Second core material] The first fluororesin prepared by the above method was filtered in the same manner as in the filtration of the fluororesin used in preparing the first core material to obtain a filtered fluororesin, which was used as the second core material.

[0133] [Clad materials] A second fluorine-containing resin was prepared as a clad material. Teflon AF1600 (manufactured by Mitsui-Chemours Fluoroproducts) as the second fluorine-containing resin and Fomblin YR (manufactured by Solvay) as a plasticizer were dissolved in a Vertrel XF-UP solvent (manufactured by Mitsui-Chemours Fluoroproducts). The mass ratio of Teflon AF1600 to Fomblin YR was 7:3. The resulting solution was filtered through a 300 nm pore size filter, LPA-SLF-003-N2 (manufactured by Roki Techno Co., Ltd.). The filtrate was then dropped into a Hastelloy container heated to 260°C to evaporate the solvent and dry the mixture. The resulting resin composition was used as a clad material.

[0134] [Reinforcing layer material] The following two reinforcing layer materials were prepared: Xylex (SABIC, glass transition temperature: 118°C) Panlite (Teijin Limited, glass transition temperature: 144°C)

[0135] [Fabrication of the POF body] Using the first core material, second core material, cladding material, and coating layer material prepared by the above-mentioned methods, POF bodies having a structure similar to that of the POF body 10 shown in Fig. 1 were fabricated by melt spinning. Three types of POF bodies with different coating layer materials were fabricated. The manufacturing apparatus shown in Fig. 3 was used to fabricate the POF bodies.

[0136] In this example, the inner diameter of the diffusion tube 120 was 4 mm. The length of the diffusion tube 120 was set so that the diffusion time was 68 minutes.

[0137] In this example, the melting temperature of the first core material was 250°C, the melting temperature of the second core material was 260°C, and the melting temperature of the clad material was 270°C. The melting temperature of the coating layer material was 250°C when Xylex was used and 270°C when Panlite was used. The temperature of the diffusion tube 120 was set to 260°C. A core was formed from the first core material and the second core material. The temperature for drawing down the second laminate consisting of the core, clad, and coating layer was 240°C.

[0138] The melt extrusion was carried out with the volume ratio of each material being 1:1.4 for the second core material, 1.6 for the cladding material, and 51 for the coating layer material.

[0139] For the POF produced in Example 1, the core diameter (outer diameter of the core) was 50 μm, the clad outer diameter was 62 μm, and the coating layer outer diameter was 231 μm.

[0140] [Evaluation of light transmission and creation of approximate formula for POF main body] A UV-curable composition containing a colorant was applied to a POF body to form a coating film, and then UV light was irradiated onto the coating film while applying tensile stress to the POF body on which the coating film was formed, to form a colored layer, and then light transmission evaluation was performed. Specifically, for two types of POF body with different coating layer materials, the tensile stress was changed between 0 and 23.0 MPa, and the UV energy was changed between 0 and 50.0 mJ / cm. 2 The colored layer was formed by varying the temperature between 0.1 and 1.0, and then the light transmittance was checked. The light transmittance evaluation was carried out by the following method.

[0141] A 60m or longer POF with a colored layer formed as described above was prepared. The tip of this POF was cut off, and the cut portion was polished with abrasive paper to make it flush, and a connector was attached. This was used as a measurement sample for light transmission evaluation. The above connector of the measurement sample was connected to the GOF of an optical time domain reflectometer (OTDR) for measurement. Light with a wavelength of 850nm was passed through the OTDR to measure the light intensity of the backscattered light. If loss could be measured from the obtained light intensity profile, the loss was calculated. In the obtained light intensity profile, the numerical value of the smooth linear portion without sudden fluctuations was read, and the loss was calculated using the following formula.

[0142] Loss (dB / km) = Difference in transmitted light intensity (dB) ÷ POF length (m)

[0143] The light transmittance was judged by visually checking the obtained light intensity profile for sudden fluctuations in light intensity. Specifically, a sample without sudden changes in light intensity was judged as light transmittance, and a sample with sudden fluctuations of 10 dB or more in light intensity was judged as light transmittance impossibility, referring to the scale of the visually obtained light intensity profile. In addition, a sample was also judged as light transmittance impossibility when the loss was 20 dB / km or more lower than the loss of the POF (i.e., the POF main body) before the colored layer was formed, according to the above calculation formula.

[0144] From the evaluation results, an approximation formula (light blocking threshold) for the boundary between conditions under which no problems occur with light transmission (light passing conditions) and conditions under which problems occur with light transmission (i.e., conditions under which light is blocked or not passing) was obtained, and the approximation formula shown in Figure 5, i.e., the above relational formulas (1) to (3), was obtained.

[0145] Example 1 The POF body was fabricated in the same manner as the POF body fabricated when determining the relations (1) to (3), except that Xylex was used as the coating material.

[0146] The ultraviolet-curable composition containing the colorant was stirred for 30 minutes or more before coating, and then the stirred ultraviolet-curable composition was poured into a metal container (coating liquid tank).

[0147] Using the manufacturing apparatus shown in Figure 4, a UV-curable composition was applied to the POF body to form a coating film. The metal container was connected to a coating device, and the UV-curable composition in the metal container was supplied to the coating device. After forming a coating film by applying the UV-curable composition to the POF body, a tensile stress of 29.7 mJ / cm was applied to the POF body. 2 That is, in Example 1, the colored layer was formed such that the glass transition temperature Tg1 of the outermost layer of the POF body satisfied the relational expression (4), and the tensile stress and ultraviolet energy satisfied the relational expressions (1) to (3).

[0148] <Comparative Example 1> When forming the colored layer, the tensile stress applied to the POF body was set to 19.8 MPa, and the ultraviolet energy was set to 29.7 mJ / cm 2 POFs were produced in the same manner as in Example 1, except for the change in the temperature of the outermost layer of the POF body. That is, in Comparative Example 1, although the glass transition temperature Tg1 of the outermost layer of the POF body satisfied the relational expression (4), the colored layer was formed by the tensile stress and ultraviolet energy that did not satisfy the relational expression (1).

[0149] <Transmission loss evaluation> The transmission loss of the POFs of the Examples and Comparative Examples was measured both before and after the formation of the colored layer. As a result, an increase in transmission loss was confirmed in the POF of Comparative Example 1 due to the formation of the colored layer, but no increase in transmission loss was confirmed in Example 1. Fig. 6 is a graph showing the results of light transmission evaluation (i.e., light intensity profile) using an OTDR according to the above-mentioned method, which was performed to determine the loss of the POFs of the Examples. Fig. 7 is a graph showing the results of light transmission evaluation (i.e., light intensity profile) using an OTDR according to the above-mentioned method, which was performed to determine the loss of the POF of the Comparative Example.

[0150] [Note] To summarize the above, one aspect of the present disclosure is as follows.

[0151] (1) A method for manufacturing a plastic optical fiber comprising a plastic optical fiber body and a colored layer covering the outer periphery of the plastic optical fiber body, The manufacturing method includes: (I) providing the plastic optical fiber body; (II) applying an ultraviolet-curable composition containing a colorant to the surface of the plastic optical fiber body to form a coating film; (III) applying a tensile stress in the longitudinal direction to the plastic optical fiber body on which the coating film is formed, and irradiating the coating film with ultraviolet light to harden the coating film, thereby forming the colored layer; Including, In the above (III), the tensile stress σ d (MPa) and the energy E (mJ / cm 2 ) satisfies the following relations (1) to (4): Manufacturing method of plastic optical fiber. σ d ≦aE 2 +bE+23 …(1) a=10 -7 Tg1 2 -0.0001Tg1+0.0153 …(2) b=-4×10 -5 Tg1 2 +0.0195Tg1-2.0987 …(3) 100≦Tg1≦150 …(4) In the above relational expressions (2) to (4), Tg1 is the glass transition temperature (° C.) of the material forming the outermost layer of the plastic optical fiber body.

[0152] (2) In (III), the energy E (mJ / cm 2 ) is 10 mJ / cm 2 That's all. A method for producing a plastic optical fiber according to (1) above.

[0153] (3) In the above (III), the tensile stress σ d (MPa) is 5 MPa or more, A method for producing a plastic optical fiber according to (1) or (2) above.

[0154] (4) In (III), the energy E (mJ / cm 2 ) is 50mJ / cm 2 Below is the A method for producing a plastic optical fiber according to any one of (1) to (3) above.

[0155] (5) In the above (III), the tensile stress σ d (MPa) is 20 MPa or less, The method for producing a plastic optical fiber according to (3) above.

[0156] (6) the outermost layer of the plastic optical fiber body contains a polycarbonate resin; A method for producing a plastic optical fiber according to any one of (1) to (5) above.

[0157] (7) The ultraviolet-curable composition contains an ultraviolet-curable polyfunctional acrylate and the colorant. A method for producing a plastic optical fiber according to any one of (1) to (6) above.

[0158] (8) The plastic optical fiber body is The core and a cladding disposed on the outer periphery of the core; a coating layer disposed on the outer periphery of the cladding; Equipped with the coating layer is the outermost layer, When the glass transition temperature (°C) of the core material is defined as Tg2, The difference between the glass transition temperature Tg2 and the glass transition temperature Tg1 is 10°C or more. A method for producing a plastic optical fiber according to any one of (1) to (7) above.

[0159] (9) The glass transition temperature Tg2 is higher than the glass transition temperature Tg1. The method for producing a plastic optical fiber according to (8) above.

[0160] (10) The plastic optical fiber body is The core and a cladding disposed on the outer periphery of the core; a coating layer disposed on the outer periphery of the cladding; Equipped with the coating layer is the outermost layer, When the glass transition temperature (°C) of the core material is defined as Tg2, The glass transition temperature Tg2 is higher than the glass transition temperature Tg1. A method for producing a plastic optical fiber according to any one of (1) to (7) above.

[0161] (11) A plastic optical fiber manufacturing apparatus for carrying out the plastic optical fiber manufacturing method according to any one of (1) to (9) above, The manufacturing apparatus includes: a coating device that applies the ultraviolet curable composition to the surface of the plastic optical fiber body being transported to form a coating film; a curing device that is disposed downstream of the coating device in the conveying direction of the plastic optical fiber body, and that applies tensile stress in the longitudinal direction to the plastic optical fiber body on which the coating film is formed, while irradiating the coating film with ultraviolet light to cure the coating film; Equipped with the curing device applies the tensile stress to the plastic optical fiber body and irradiates the ultraviolet light so as to satisfy the relational expressions (1) to (4). Plastic optical fiber manufacturing equipment. [Industrial Applicability]

[0162] The POF manufacturing method and manufacturing apparatus disclosed herein can manufacture POFs with colored layers formed thereon while suppressing increases in transmission loss, and are therefore suitable for manufacturing POFs that require high speed and large capacity, such as POFs contained in active optical cables (AOCs). [Explanation of symbols]

[0163] 1a First core material 1b Second core material 1c Cladding material 1d resin composition 2. Core inner layer 3 Core outer periphery 4 Laminate (core) 5. Clad 6 Covering layer 7 Second laminate 100 POF 10 POF main body 11 cores 12 Clad 13 Covering layer 20 Colored layer 101a First extrusion device 101b Second extrusion device 101c Third extrusion device 101d Fourth extrusion device 102a First storage section 102b Second storage section 102c Third Storage Unit 102d 4th Storage Unit 103a First extrusion section 103b Second extrusion section 103c Third extrusion section 104 Screw 105 Hopper 110 Room 1 120 Diffusion tube 130 Room 2 140 Room 3 150 nozzles 160 Cooling pipe 161 Interior Space 170 Nip Roll 171,172 rolls 173,174,175 Guide Roll 176 Winding Roll 180 Displacement Meter 200 POF manufacturing equipment 210 Coating equipment 211 Coating die 212 Ultraviolet curable composition 220 Curing equipment 221 Light source 222 Irradiation room 230 Payout Roll 240 winding roll 250 guide roll 1000 POF main body manufacturing equipment

Claims

1. A method for manufacturing a plastic optical fiber comprising a plastic optical fiber body and a colored layer covering the outer periphery of the plastic optical fiber body, The manufacturing method includes: (I) providing the plastic optical fiber body; (II) applying an ultraviolet-curable composition containing a colorant to the surface of the plastic optical fiber body to form a coating film; (III) applying a tensile stress in the longitudinal direction to the plastic optical fiber body on which the coating film is formed, and irradiating the coating film with ultraviolet light to harden the coating film, thereby forming the colored layer; Including, In the above (III), the tensile stress σ d (MPa) and the energy E (mJ / cm 2 ) satisfies the following relations (1) to (4): Manufacturing method of plastic optical fiber. s d ≦ad 2 +bE+23 …(1) a=10 -7 Tg 1 2 -0.0001Tg 1 +0.0153 …(2) b=-4×10 -5 Tg 1 2 +0.0195Tg 1 -2.0987 …(3) 100≦Tg 1 ≦150 …(4) In the above relational expressions (2) to (4), Tg 1 is the glass transition temperature (°C) of the material forming the outermost layer of the plastic optical fiber body.

2. In (III), the energy E (mJ / cm 2 ) is 10 mJ / cm 2 That's all. A method for producing the plastic optical fiber according to claim 1.

3. In the above (III), the tensile stress σ d (MPa) is 5 MPa or more, A method for producing the plastic optical fiber according to claim 1.

4. In (III), the energy E (mJ / cm 2 ) is 50 mJ / cm 2 Below is the A method for producing the plastic optical fiber according to claim 1.

5. In the above (III), the tensile stress σ d (MPa) is 20 MPa or less, The method for producing the plastic optical fiber according to claim 3.

6. the outermost layer of the plastic optical fiber body contains a polycarbonate resin; A method for producing the plastic optical fiber according to claim 1.

7. The ultraviolet-curable composition contains an ultraviolet-curable polyfunctional acrylate and the colorant. A method for producing the plastic optical fiber according to claim 1.

8. The plastic optical fiber body is The core and a cladding disposed on the outer periphery of the core; a coating layer disposed on the outer periphery of the cladding; Equipped with the coating layer is the outermost layer, The glass transition temperature (°C) of the core material is Tg 2 When we define The glass transition temperature Tg 2 and the glass transition temperature Tg 1 The difference is 10°C or more. A method for producing the plastic optical fiber according to claim 1.

9. The glass transition temperature Tg 2 is the glass transition temperature Tg 1 Higher than The method for producing the plastic optical fiber according to claim 8.

10. The plastic optical fiber body is The core and a cladding disposed on the outer periphery of the core; a coating layer disposed on the outer periphery of the cladding; Equipped with the coating layer is the outermost layer, The glass transition temperature (°C) of the core material is Tg 2 When we define The glass transition temperature Tg 2 is the glass transition temperature Tg 1 Higher than A method for producing the plastic optical fiber according to claim 1.

11. A plastic optical fiber manufacturing apparatus for carrying out the plastic optical fiber manufacturing method according to any one of claims 1 to 10, The manufacturing apparatus includes: a coating device that applies the ultraviolet curable composition to the surface of the plastic optical fiber body being transported to form a coating film; a curing device that is disposed downstream of the coating device in the conveying direction of the plastic optical fiber body, and that applies tensile stress in the longitudinal direction to the plastic optical fiber body on which the coating film is formed, while irradiating the coating film with ultraviolet light to cure the coating film; Equipped with the curing device applies the tensile stress to the plastic optical fiber body and irradiates the ultraviolet light so as to satisfy the relational expressions (1) to (4). Plastic optical fiber manufacturing equipment.

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