JP2015203710A - polymer optical fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer optical fiber that features heat resistance, flexibility, and a large transmitted light volume.SOLUTION: A polymer optical fiber 100 comprises a core 200 made of a polymer material and cladding 300 made of a polymer material surrounding the core 200, where each of the polymer materials is a cured product of a photocurable composition and the cladding 300 has a thickness of 1-20 μm. The core 200 of the polymer optical fiber 100 preferably occupies 30% or more of cross-sectional area of the polymer optical fiber 100.

Description

  The present invention relates to a polymer optical fiber having a core and a clad (particularly, a polymer optical fiber produced using a photocurable composition (crosslinkable resin)). In particular, the present invention relates to a polymer optical fiber having a core and a thin cladding, and having a high core space factor.

  Due to the widespread use of moving image distribution via the Internet, the communication capacity within the board used for servers and routers has increased, and in recent years, consideration has been given to replacing some high-speed signal lines from electrical wiring to optical wiring. In particular, an optical fiber (polymer optical fiber) formed of a polymer material is excellent in flexibility and can be wired with a small curvature radius. As expected.

  In particular, when producing an opto-electric composite wiring using an array of optical fibers, one of the characteristics required for optical fibers is that there is an increase in light loss due to high-temperature treatment in the solder reflow process and thermal degradation such as cracks. The so-called “solder reflow heat resistance” to suppress or prevent is mentioned. In recent years, the reflow temperature has become higher in order to cope with the use of lead-free solder that requires heating at a high temperature of about 260 ° C., so that the optical fiber is required to have higher heat resistance. .

  As an example of the use of an optical fiber, there is an illumination device using a light guide fiber bundle in which optical fiber strands are bundled. In order to guide the light from the light source using such a light guide fiber bundle and emit the light in the vicinity of the object to be illuminated, the light guide fiber bundle has a light source side entrance and a light exit side. It is necessary to improve the space factor of the core of the optical fiber and increase the amount of light incident on the light receiving end face.

  Patent Document 1 discloses a light guide fiber bundle in which a large number of thin silica glass optical fibers are bundled as a light guide fiber bundle excellent in heat resistance. However, the light guide fiber bundle made of quartz glass generally has very low mechanical strength because each optical fiber is very thin. On the other hand, the polymer optical fiber as disclosed in Patent Document 2 is generally superior in flexibility as compared with the quartz glass optical fiber, but because it uses a thermoplastic resin such as PMMA as a main material, Low heat resistance.

In Patent Document 3, as a method for producing a polymer optical fiber, a nozzle for discharging a photocurable composition, and a light irradiation device for irradiating light to a filamentous photocurable composition discharged from the nozzle; And a photocurable composition for forming a core (curing for core formation) using an optical fiber manufacturing apparatus comprising a control means for setting the irradiation intensity of light at the nozzle outlet to 0.2 mW / cm ² or less. And a photocurable composition for forming a clad (curable composition for forming a clad) are simultaneously extruded and photocured to produce a polymer optical fiber.

Japanese Patent Laid-Open No. 2003-121661 JP 2003-185855 A JP 2012-159804 A

  By the way, as a method for producing a polymer optical fiber, there is known a production method in which a photo-curing resin (cationic polymerizable resin) is reacted while being irradiated with ultraviolet light (for example, JP-A-61-245109). etc). In this production method, liquid epoxy resin containing an ultraviolet curing agent is placed in a heating container of a normal drawing device, and heated to a constant temperature with a heater so that it can easily flow out of the line reference nozzle and have a constant wire diameter. It is necessary to reduce the viscosity. Moreover, the said manufacturing method is a method of producing the core used as the optical conduction part first, and forming the clad which coat | covers this core later.

  In general, when a polymer optical fiber having a core and a clad (polymer optical fiber having a core-clad structure) is used in connection with a light source device or the like, the center of the core (center axis) and the center of the clad (center axis) are accurate. A good match is required. However, after the core is manufactured, it is difficult to manufacture a polymer optical fiber in which the core and the center (center axis) of the cladding coincide with each other by the method of covering the core with the cladding. In addition, the production of the polymer optical fiber by the above production method has to be performed in a clean environment such as a clean room in order to prevent foreign matters from adhering to the surface of the core.

  Similarly, generally known polymer optical fibers made of thermoplastic resins and optical fibers made of quartz are manufactured by first forming a core and then forming a cladding on the surface of the core. Therefore, it is necessary to manufacture these optical fibers in a clean environment such as a clean room in order to prevent foreign matter from adhering to the surface of the core. Further, due to the manufacturing method, in these optical fibers, there has been a problem that it is difficult to match the centers of the core and the clad.

  On the other hand, according to the method described in Patent Document 4, since the core and the clad are simultaneously formed, it is easy to produce a polymer optical fiber in which the centers of the core and the clad are accurately aligned. Since it is formed from the polymer (cured material) of the adhesive composition, there is a merit that heat resistance and flexibility are high.

  However, as a result of further investigation on the method described in Patent Document 4, the present inventors have found that there is room for further improvement in the following points (1) to (3). That is, (1) when a radical polymerizable composition is used as the curable composition for forming a clad, the clad is difficult to be cured due to polymerization inhibition (curing inhibition) by oxygen, and it is difficult to produce a polymer optical fiber. (2) When the viscosity of the curable composition for forming a clad is low, the spinnability is poor and it is difficult to produce a polymer optical fiber; therefore, the clad material cannot be determined only by optical properties. Therefore, if the viscosity of the curable composition for forming a clad is increased in order to improve the spinnability, light scattering is required from the viewpoint of productivity, workability, and operability. It is difficult to remove the causative minute foreign matter by filtration. (3) An optical fiber having a large core space factor in order to produce a fiber bundle and use it as a light guide. However, if a polymer optical fiber with a thin clad thickness is to be manufactured by the above method, it is difficult to manufacture the polymer optical fiber with a thin clad thickness due to insufficient spinnability. I found that there was a problem.

Accordingly, an object of the present invention is to provide a polymer optical fiber having both heat resistance and flexibility and having a large amount of transmitted light.
Another object of the present invention is to provide a polymer optical fiber in which the central axes of the core and the clad coincide with each other with high accuracy, the fine foreign matter is highly reduced, and the productivity is excellent.

  The inventors of the present invention provide a polymer optical fiber having a core and a clad, wherein each of the polymer materials constituting the core and the clad is a cured product of a photocurable composition, and the thickness of the clad is specified. The present inventors have found that a polymer optical fiber controlled in a range has both heat resistance and flexibility, and has a large amount of transmitted light, thereby completing the present invention.

  That is, the present invention is an optical fiber having a core made of a polymer material and a clad made of a polymer material covering the core, and each of the polymer materials is a photocurable composition. Provided is a polymer optical fiber, which is a cured product of the product, wherein the clad has a thickness of 1 to 20 μm.

  Furthermore, the polymer optical fiber having a core space factor of 30% or more is provided.

  Further, a curable composition for forming a core for forming a polymer material constituting a core and a curable composition for forming a clad for forming a polymer material constituting a clad are Manufactured by a method in which the core-forming curable composition and the clad-forming curable composition are cured by light irradiation in a form corresponding to the form of the core and clad of the molecular optical fiber and simultaneously ejected coaxially into a fiber shape. The polymer optical fiber is provided.

  Furthermore, the polymer optical fiber according to the present invention, wherein each of the core-forming curable composition and the cladding-forming curable composition is a photo-radical polymerizable composition.

  Furthermore, the photoradical polymerizable composition is at least selected from the group consisting of (meth) acryloyl group, (meth) acryloyloxy group, (meth) acryloylamino group, vinylaryl group, vinyl ether group, and vinyloxycarbonyl group. Provided is the above-described polymer optical fiber comprising a radically polymerizable compound having at least one kind of radically polymerizable group in the molecule.

  Furthermore, the polymer optical fiber according to the present invention, wherein one or both of the curable composition for core formation and the curable composition for clad formation contains an antioxidant.

  Since the polymer optical fiber of the present invention has the above-described configuration, it has both heat resistance and flexibility and has a large amount of transmitted light. In addition, as a composition for forming the polymer material constituting the core (curable composition for core formation) and a composition for forming the polymer material constituting the cladding (curable composition for clad formation) By using the photo-radical polymerizable composition, in particular, the above-described polymer optical fiber with even lower light loss can be produced. Furthermore, the above-mentioned polymer optical fiber having particularly excellent heat resistance can be produced by adding an antioxidant to one or both of the curable composition for forming a core and the curable composition for forming a clad. In particular, the polymer optical fiber is a polymer optical fiber manufactured by the “method for manufacturing a polymer optical fiber of the present invention” described later, so that the central axes of the core and the clad coincide with each other with high accuracy, and a minute foreign matter. Is highly reduced, and a polymer optical fiber excellent in productivity can be obtained. As described above, the polymer optical fiber of the present invention is a polymer optical fiber that is very advantageous in terms of quality and cost.

It is the schematic which shows an example of the polymer optical fiber of this invention, (a) shows a perspective view, (b) shows the YY sectional drawing in (a). It is the schematic which shows an example of the process A of the manufacturing method of the polymeric optical fiber of this invention. It is the schematic (in the case of a triple tube nozzle; sectional drawing of the longitudinal direction of a pipe | tube) which shows an example of a multiple tube nozzle. It is the schematic (sectional drawing of the radial direction of a pipe | tube) showing an example of the multi-tube nozzle provided with the position adjustment mechanism. It is the schematic which shows one Embodiment of the process A in the manufacturing method of the polymer optical fiber of this invention. It is the schematic (plan view) which shows the example of a light irradiation apparatus, (a) shows the light irradiation apparatus which can irradiate light from three directions, (b) shows the light irradiation apparatus which can irradiate light from two directions. It is the schematic (perspective view) which shows the example of a light shielding member, (a) is a light shielding cylinder, (b) is a light shielding plate (disk-shaped light shielding plate), (c) is a light shielding plate (conical light shielding plate). Indicates. It is the schematic (side view) explaining the divergence angle (psi) of the light radiate | emitted from the light irradiation apparatus. It is the schematic (side view) explaining the relationship between the angle (theta) which the direction of the light ray with which irradiation intensity becomes the maximum, and the surface perpendicular | vertical to the discharge direction of the composition for polymeric optical fiber formation, and the light spread angle (psi). (A) is a schematic view when θ ≧ ψ / 2, and (b) is a schematic view when θ <ψ / 2. It is the schematic (side view) which shows an example of a light irradiation apparatus provided with an irradiation angle adjustment mechanism. It is the schematic which shows the manufacturing method of the polymer optical fiber used in the Example, and the manufacturing method of the polymer optical fiber using this manufacturing apparatus. It is the schematic which shows the manufacturing method of the polymer optical fiber used in the comparative example, and the manufacturing method of the polymer optical fiber using this manufacturing apparatus.

  The polymer optical fiber of the present invention is an optical fiber having a multi-layer structure of two or more having a core made of a polymer material and a clad covering the core and made of a polymer material, Each of the polymer materials is a cured product of a photocurable composition, and the thickness of the clad is 1 to 20 μm.

  FIG. 1 is a schematic view showing an example of a polymer optical fiber of the present invention, in which (a) shows a perspective view and (b) shows a YY sectional view in (a). As shown in FIG. 1, the polymer optical fiber 100 of the present invention has at least a structure in which a core 200 is covered with a clad 300. The polymer optical fiber of the present invention is not limited to the polymer optical fiber having the configuration shown in FIG. 1, and may be, for example, a polymer optical fiber having a core covered with a clad having a multilayer structure having two or more layers. May be. However, in the case of having a multilayer clad, the total thickness of these clads (the total thickness of each clad) is 1 to 20 μm.

  In the polymer optical fiber of the present invention, generally, light propagates in the longitudinal direction (length direction) of the polymer optical fiber through the core. The clad in the polymer optical fiber of the present invention is located outside the core. As described above, the clad may have a single layer configuration or may have a multilayer configuration (multilayer configuration).

  The diameter of the core (core diameter) and the diameter of the cladding (cladding diameter) in the polymer optical fiber of the present invention are not particularly limited, and are preferably 5 to 2000 μm, for example, because the cladding diameter is larger than the core diameter. It adjusts suitably in the range (more preferably 10-1000 micrometers).

As described above, the thickness of the clad in the polymer optical fiber of the present invention is 1 to 20 μm, preferably 1 to 15 μm. By setting the thickness of the clad to 20 μm or less, the amount of transmitted light per unit cross-sectional area of the polymer optical fiber is increased, and for example, it can be preferably used as a polymer optical fiber constituting a light guide fiber bundle. On the other hand, when the thickness of the clad is 1 μm or more, the protection of the core is improved. In addition, the thickness of the clad in the polymer optical fiber of the present invention can be calculated from the following formula using the following diameter observed and measured from the cross section (radial section) of the polymer optical fiber. In addition, the said observation and measurement can be implemented using a digital microscope, for example.
[Clad thickness (μm)] = ([Polymer optical fiber diameter (μm)] − [Core diameter (μm)]) / 2

The space factor of the core in the polymer optical fiber of the present invention is not particularly limited, but is preferably 30% (area%) or more (for example, 30 to 80%), more preferably 40 to 80%. By setting the core space factor to 30% or more, the amount of light transmitted through the polymer optical fiber tends to be further improved. On the other hand, when the core space factor is 80% or less, the core protection tends to be further improved. In addition, the space factor of a core is computable from a following formula using the following area observed and measured from the cross section (radial direction cross section) of a polymer optical fiber. In addition, the said observation and measurement can be implemented using a digital microscope, for example.
[Core space factor (%)] = ([Cross sectional area of core (μm ² )] / [Cross sectional area of polymer optical fiber (μm ² )]) × 100

  The polymer material constituting the core and the polymer material constituting the clad in the polymer optical fiber of the present invention are both cured products (polymers) of a photocurable composition (photopolymerizable composition). That is, a composition for forming a polymer material constituting the core in the polymer optical fiber of the present invention (sometimes referred to as a “core-forming curable composition”) and a clad in the polymer optical fiber of the present invention. The composition for forming the constituting polymer material (sometimes referred to as “clad-forming curable composition”) is a photocurable composition. For this reason, the polymer optical fiber of the present invention has excellent heat resistance and flexibility.

  Examples of the photocurable composition include known or commonly used photocurable compositions (photoradical polymerizable composition, light, which can be cured (polymerized) by light irradiation to form a cured product (polymer material). Cationic polymerizable composition, photoanionic polymerizable composition, etc.) can be used. Among these, the photocurable composition is easy to handle and can use a general photoinitiator, so that it can be polymerized by irradiation with ultraviolet rays to give a polymer material ( An ultraviolet curable composition is preferred. In particular, a photo-cationic polymerizable composition and a photo-radical polymerizable composition are preferable in terms of wide selection of materials.

(Photocationic polymerizable composition)
As said photocationic polymerizable composition, the composition etc. which contain a cationically polymerizable compound as an essential component, and also contain a photocationic polymerization initiator, a photoacid generator, etc. as needed are mentioned, for example. The cationic polymerizable compound is a compound having one or more cationic polymerizable groups in the molecule (in one molecule). Examples of the cationic polymerizable group include an oxetane ring (oxetanyl group), an epoxy ring (oxiranyl group), a vinyl ether group, and a vinyl aryl group.

Among the above cationic polymerizable compounds, in particular, from the viewpoint of the transparency, heat resistance and flexibility of the polymer optical fiber, the oxetane ring-containing (meth) acrylic acid ester compound represented by the following formula (1) alone or Cationic polymerizable resins (cationic polymerizable polymers or copolymers) obtained by radical polymerization with other compounds having radical polymerizability are preferred. That is, the photo-cationic polymerizable composition is preferably a photo-curable resin composition (photo-cationic polymerizable resin composition) containing the cationic polymerizable resin as an essential component. Since the photocurable resin composition (photocationic polymerizable resin composition) has a low viscosity, it tends to be excellent in workability. In addition, the said cationically polymerizable resin is a polymer which contains the oxetane ring derived from the oxetane ring containing (meth) acrylic acid ester compound represented by Formula (1) in a molecule | numerator.

In the present specification, “(meth) acryl” means either or both of acryl and methacryl, and the same applies to “(meth) acryloyl”, “(meth) acrylate”, and the like. However, “(meth) acryl” in the oxetane ring-containing (meth) acrylic acid ester compound includes not only acrylic and methacrylic but also the meaning of CH ₂ ═CR ¹ CO— in which R ¹ is an alkyl group other than a methyl group. Shall be.

In formula (1), R ¹ and R ² are the same or different and each represents a hydrogen atom or an alkyl group. As the alkyl group in R ¹ and R ^2, an alkyl group having 1 to 6 carbon atoms (C _1-6 ) is preferable, and examples thereof include straight groups such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. Chain C _1-6 (preferably C _1-3 ) alkyl group; isopropyl group, isobutyl group, s-butyl group, t-butyl group, isopentyl group, s-pentyl group, t-pentyl group, isohexyl group, Examples thereof include branched C _3-6 (preferably C ₃ ) alkyl groups such as s-hexyl group and t-hexyl group. Among them, as R ¹ , a hydrogen atom or a methyl group is preferable, and as R ² , a methyl group or an ethyl group is preferable.

In the formula (1), A represents a linear or branched alkylene group having 2 to 20 carbon atoms. Among these, a linear alkylene group represented by the following formula (a1) or the following formula (a2) is preferable in that a polymer optical fiber having both excellent heat resistance and flexibility can be formed. A branched alkylene group is preferred. Note that the right end of the formula (a2) is bonded to an oxygen atom constituting an ester bond.

  N1 in Formula (a1) represents an integer of 2 or more. As n1, the integer of 2-20 is preferable, More preferably, it is an integer of 2-10. When n1 is 1, the flexibility of the polymer optical fiber tends to decrease.

In formula (a2), R ³ , R ⁴ , R ⁷ and R ⁸ are the same or different and each represents a hydrogen atom or an alkyl group. R ⁵ and R ⁶ are the same or different and each represents an alkyl group. The alkyl group in R ³ to R ^8, is not particularly limited, preferably an alkyl group having 1 to 4 carbon atoms, such as methyl group, ethyl group, propyl group, C _1-4 straight-chain and butyl group (Preferably C _1-3 ) alkyl group; branched C _3-4 (preferably C ₃ ) alkyl group such as isopropyl group, isobutyl group, s-butyl group, t-butyl group and the like can be mentioned. Among these, as R ³ and R ⁴ , a hydrogen atom is preferable, and as R ⁵ and R ⁶ , a methyl group and an ethyl group are preferable.

N2 in Formula (a2) represents an integer of 0 or more. As n2, the integer of 1-20 is preferable, More preferably, it is an integer of 1-10. When n2 is an integer of 2 or more, 2 or more of R ⁷ and R ⁸ may be the same or different.

Typical examples of the oxetane ring-containing (meth) acrylic acid ester compound represented by the formula (1) include the following compounds.

  The oxetane ring-containing (meth) acrylic acid ester compound represented by the formula (1) can be produced by a known or conventional method, and the production method is not particularly limited. For example, International Publication No. 2011/099352 Or by the method described in International Publication No. 2011/129268.

  The cationic polymerizable resin can be obtained by radical polymerization of the oxetane ring-containing (meth) acrylic acid ester compound represented by the formula (1) alone or with other compounds having radical polymerizability. In addition, said "other compound which has radical polymerizability" has radical polymerizability, and is the oxetane ring containing (meth) acrylic acid ester compound represented by Formula (1), and the radical polymerizable resin mentioned later Hereinafter, they are different compounds and may be referred to as “other radically polymerizable compounds”.

［式中、Ｒ¹、Ｒ²、Ａは上記に同じ。］ Since the oxetane ring-containing (meth) acrylic acid ester compound represented by the formula (1) has an oxetane ring as a cationic polymerization site and a (meth) acryloyl group as a radical polymerization site in the molecule, it is radical polymerization alone. Or a cationically copolymerizable resin having a structural unit represented by the following formula (repeating structural unit) by radical copolymerization with other radical polymerizable compounds. The radical copolymerization includes block copolymerization and random copolymerization.

[Wherein R ¹ , R ² and A are the same as above. ]

  Among the above cationic polymerizable resins, the oxetane ring-containing (meth) acrylic acid ester compound represented by the formula (1) and other radical polymerizable compounds are particularly preferable in that a polymer optical fiber excellent in flexibility can be formed. Is preferably a resin obtained by radical copolymerization, and the proportion of the oxetane ring-containing (meth) acrylic acid ester compound represented by the formula (1) is 0.1 wt. % To less than 100% by weight (more preferably from 1 to 99% by weight, even more preferably from 10 to 80% by weight, particularly preferably from 10 to 50% by weight). Is preferred.

  Examples of the other radical polymerizable compounds include radical polymerizable groups such as (meth) acryloyl group, (meth) acryloyloxy group, (meth) acryloylamino group, vinyl ether group, vinylaryl group, vinyloxycarbonyl group and the like. Examples thereof include compounds having one or more in the molecule.

  Examples of the compound having at least one (meth) acryloyl group in the molecule include 1-buten-3-one, 1-penten-3-one, 1-hexen-3-one, and 4-phenyl-1-butene. -3-one, 5-phenyl-1-penten-3-one, and derivatives thereof.

  Examples of the compound having one or more (meth) acryloyloxy groups in the molecule include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl ( (Meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isodecyl (meth) acrylate, n-lauryl (meth) acrylate, n-stearyl (meth) acrylate, n-butoxyethyl (meth) acrylate , Butoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, cyclohexyl (meth) acrylate, tetrahydrofurfuryl (meth) a Relate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, isobornyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, dimethylamino Ethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, acrylic acid, methacrylic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, 2- (meth) acryloyloxy Ethyl-2-hydroxypropyl phthalate, glycidyl (meth) acrylate, 2- (meth) acryloyloxyethyl acid phosphate, ethylene glycol di (meth) acrylate, die Lenglycol di (meth) acrylate, triethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, glycerin di (meth) acrylate, 2-hydroxy-3- (meth) acryloyloxypropyl (meth) acrylate, dimethylol Tricyclodecane di (meth) acrylate, trifluoroethyl (meth) acrylate, perfluorooctylethyl (meth) acrylate, isoamyl (meth) acrylate, isomyristyl (meth) acrylate, γ- (meth) acryloyloxy Propyltrimethoxysilane, 2- (meth) acryloyloxyethyl isocyanate, 1,1-bis {(meth) acryloyloxy} ethyl isocyanate, 2- {2- (meth) acryloyloxyethyloxy} ethyl isocyanate, 3- ( And (meth) acryloyloxypropyltriethoxysilane, and derivatives thereof.

  Examples of the compound having one or more (meth) acryloylamino groups in the molecule include 4- (meth) acryloylmorpholine, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N- Methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, Nn-butoxymethyl (meth) acrylamide, N -Hexyl (meth) acrylamide, N-octyl (meth) acrylamide, etc., and derivatives thereof.

  Examples of the compound having one or more vinyl ether groups in the molecule include 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2-hydroxypropyl vinyl ether, 2-hydroxyisopropyl vinyl ether, 4-hydroxybutyl vinyl ether, 3-hydroxybutyl. Vinyl ether, 2-hydroxybutyl vinyl ether, 3-hydroxyisobutyl vinyl ether, 2-hydroxyisobutyl vinyl ether, 1-methyl-3-hydroxypropyl vinyl ether, 1-methyl-2-hydroxypropyl vinyl ether, 1-hydroxymethylpropyl vinyl ether, 4-hydroxy Cyclohexyl vinyl ether, 1,6-hexanediol monovinyl ether, 1,4-cyclohexane dimeta Monovinyl ether, 1,3-cyclohexanedimethanol monovinyl ether, 1,2-cyclohexanedimethanol monovinyl ether, p-xylene glycol monovinyl ether, m-xylene glycol monovinyl ether, o-xylene glycol monovinyl ether, diethylene glycol monovinyl ether, tri Ethylene glycol monovinyl ether, tetraethylene glycol monovinyl ether, pentaethylene glycol monovinyl ether, oligoethylene glycol monovinyl ether, polyethylene glycol monovinyl ether, dipropylene glycol monovinyl ether, tripropylene glycol monovinyl ether, tetrapropylene glycol monovinyl ether, pentapropylene group Glycol monomethyl ether, oligo propylene glycol monomethyl ether, polypropylene glycol monovinyl ether, and derivatives thereof.

  Examples of the compound having at least one vinylaryl group in the molecule include styrene, divinylbenzene, methoxystyrene, ethoxystyrene, hydroxystyrene, vinylnaphthalene, vinylanthracene, 4-vinylphenyl acetate, and (4-vinylphenyl) dihydroxy. Examples thereof include borane, N- (p-vinylphenyl) maleimide, and derivatives thereof.

  Examples of the compound having one or more vinyloxycarbonyl groups in the molecule include, for example, isopropenyl formate, isopropenyl acetate, isopropenyl propionate, isopropenyl butyrate, isopropenyl isobutyrate, isopropenyl caproate, isopropenyl valerate, Isopropenyl isovalerate, isopropenyl lactate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl caprylate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylate, pivalin Vinyl acetate, vinyl octylate, vinyl monochloroacetate, divinyl adipate, vinyl acrylate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl benzoate, vinyl cinnamate, etc. Body, and the like.

  As other radical polymerizable compounds, vinyl silanes such as vinyltrimethoxysilane and vinyltriethoxysilane can also be used.

  Among the other radical polymerizable compounds, a (meth) acryloyl group, a (meth) acryloyloxy group, a (meth) acrylic group can be formed in the molecule in that a polymer optical fiber excellent in flexibility and heat resistance can be formed. ) A compound having only one radical polymerizable group selected from the group consisting of an acryloylamino group, a vinylaryl group, a vinyl ether group, and a vinyloxycarbonyl group is preferred, and in particular, n-butyl (meth) acrylate, isobutyl (meta ), Tert-butyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate and other compounds having only one (meth) acryloyloxy group in the molecule are preferred. As the other radical polymerizable compound as the monomer component of the cationic polymerizable resin, one kind can be used alone, or two or more kinds can be used in combination.

  The cationic polymerizable resin can be produced by a known or conventional method (for example, radical polymerization reaction), and the production method is not particularly limited. For example, the method described in International Publication No. 2011/099352 can be used. Can be manufactured.

  Although the weight average molecular weight of the said cation polymeric resin is not specifically limited, 500 or more (for example, 500-1 million) are preferable, More preferably, it is 3000-500,000. When the weight average molecular weight of the cationic polymerizable resin is out of the above range, the flexibility of the polymer optical fiber tends to be difficult to obtain.

  Although the number average molecular weight of the said cation polymeric resin is not specifically limited, 100 or more (for example, 100-500,000) are preferable, More preferably, it is 300-250,000. If the number average molecular weight of the cationic polymerizable resin is out of the above range, the flexibility of the polymer optical fiber tends to be difficult to obtain. In addition, the weight average molecular weight and number average molecular weight of the said cation polymeric resin can be measured as a value of standard polystyrene conversion by GPC (gel permeation chromatography) method, for example.

  When the cationic photopolymerizable composition contains the cationic polymerizable resin, the proportion (content) of the cationic polymerizable resin is not particularly limited, but is preferably 5% by weight or more, and is substantially a cationic photopolymerizable composition. The thing may be comprised only with the said cationically polymerizable resin. Among them, the proportion of the cationic polymerizable resin is more preferably 10 to 95% by weight, and still more preferably 40 to 95% by weight, in that a polymer optical fiber having more flexibility can be formed. When the proportion of the cationic polymerizable resin is less than 5% by weight, the flexibility of the polymer optical fiber tends to be lowered.

  The above cationic photopolymerizable composition contains, as the cationic polymerizable compound, a compound other than the oxetane ring-containing (meth) acrylic acid ester compound represented by the formula (1) and the cationic polymerizable resin (“other cationic polymerizable compounds”). May be referred to as "compound"). Examples of the other cationically polymerizable compounds include compounds having one or more cationically polymerizable groups such as oxetane ring, epoxy ring, vinyl ether group, and vinylaryl group in the molecule.

  Examples of the compound having one or more oxetane rings in the molecule include 3,3-bis (vinyloxymethyl) oxetane, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, 3-ethyl-3- ( Hydroxymethyl) oxetane, 3-ethyl-3-[(phenoxy) methyl] oxetane, 3-ethyl-3- (hexyloxymethyl) oxetane, 3-ethyl-3- (chloromethyl) oxetane, 3,3-bis ( Chloromethyl) oxetane, 1,4-bis [(3-ethyl-3-oxetanylmethoxy) methyl] benzene, bis {[1-ethyl (3-oxetanyl)] methyl} ether, 4,4′-bis [(3 -Ethyl-3-oxetanyl) methoxymethyl] bicyclohexyl, 1,4-bis [(3-ethyl-3-oxetanyl) meth Shimechiru] cyclohexane, 3-ethyl-3 - {[(3-ethyloxetan-3-yl) methoxy] methyl} oxetane, and the like.

  Examples of the compound having one or more epoxy rings in the molecule include bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, brominated bisphenol A diglycidyl ether, brominated bisphenol F diglycidyl ether, Brominated bisphenol S diglycidyl ether, epoxy novolac resin, hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol F diglycidyl ether, hydrogenated bisphenol S diglycidyl ether, 3,4-epoxycyclohexylmethyl (3,4-epoxy) Cyclohexanecarboxylate, 2- (3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy) cyclohexane-meta-dioxane, bis (3,4-epoxy Cycyclohexylmethyl) adipate, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, 3,4-epoxy-6-methylcyclohexyl-3 ′, 4′-epoxy-6′-methylcyclohexanecarboxylate, methylenebis (3,4-epoxycyclohexane), dicyclopentadiene diepoxide, ethylene glycol di (3,4-epoxycyclohexylmethyl) ether, ethylene bis (3,4-epoxycyclohexanecarboxylate), dioctyl epoxyhexahydrophthalate, epoxy Hexahydrophthalic acid di-2-ethylhexyl, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin triglycidyl ether, trimethylol Lopantriglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, etc .; obtained by adding one or more alkylene oxides to aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol and glycerin Polyglycidyl ethers of polyether polyols; diglycidyl esters of aliphatic long-chain dibasic acids; monoglycidyl ethers of higher aliphatic alcohols; polyethers obtained by adding phenol, cresol, butylphenol or alkylene oxides to these Monoglycidyl ethers of the above; glycidyl esters of higher fatty acids and the like.

  Examples of the compound having one or more vinyl ether groups in the molecule and the compound having one or more vinyl aryl groups in the molecule include compounds similar to those exemplified as the other radical polymerizable compounds.

  Among these other cationically polymerizable compounds, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, 3,3-bis (vinyloxymethyl) oxetane, , 4-bis {[(3-ethyl-3-oxetanyl) methoxy] methyl} benzene, 3-ethyl-3-{[(3-ethyloxetane-3-yl) methoxy] methyl} oxetane, etc. A compound having one or more thereof is preferred. In addition, the said other cationically polymerizable compound can also be used individually by 1 type, and can also be used in combination of 2 or more type.

  In the said cationic photopolymerizable composition, the oxetane ring containing (meth) acrylic acid ester compound represented by Formula (1) can also be used as a cationically polymerizable compound.

  It is preferable that the said cationic photopolymerizable composition contains the said cationic polymerizable resin and another cationically polymerizable compound at the point which can form the polymeric optical fiber which is more excellent in a softness | flexibility. The blending ratio (the former / the latter: weight ratio) of the cationic polymerizable resin and the other cationic polymerizable compound is not particularly limited, but is preferably 95/5 to 10/90, more preferably 95/5 to 20/80. More preferably, it is 95/5 to 40/60. When the blending ratio of the cationic polymerizable resin is below the above range, the flexibility of the resulting polymer optical fiber tends to decrease.

  The said cationic photopolymerizable composition may contain the polymerization initiator as needed. Examples of the polymerization initiator include those that can cause cationic polymerization such as known or commonly used cationic photopolymerization initiators and photoacid generators, and are not particularly limited. For example, triarylsulfonium hexafluorophosphate, Sulfonium salts such as triarylsulfonium hexafluoroantimonate; diaryliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, bis (dodecylphenyl) iodonium tetrakis (pentafluorophenyl) borate, iodonium [4- (4-methylphenyl-2 -Methylpropyl) phenyl] iodonium salts such as hexafluorophosphate; phosphonium salts such as tetrafluorophosphonium hexafluorophosphate; pyridinium salts and the like It is below.

  As the polymerization initiator, for example, commercially available products such as trade name “CPI-100P” (manufactured by San Apro Co., Ltd.) and trade name “CPI-101A” (manufactured by San Apro Co., Ltd.) can be used.

  The content (blending amount) of the polymerization initiator in the photo-cationic polymerizable composition is not particularly limited, but the total amount of the cationically polymerizable compound (for example, the total weight of the cationically polymerizable resin and other cationically polymerizable compounds) is 100. 0.01-50 weight part is preferable with respect to weight part, More preferably, it is 0.1-20 weight part.

  The photocationically polymerizable composition may contain an antioxidant. In particular, when the photo-cationic polymerizable composition is used as a curable composition for forming a core and a curable composition for forming a cladding, any one of the curable composition for forming a core and the curable composition for forming a cladding. One or both preferably contain an antioxidant. As the antioxidant, known or commonly used antioxidants can be used, and are not particularly limited. For example, phenolic compounds (phenolic antioxidants), hindered amine compounds (hindered amine antioxidants), Phosphorus compounds (phosphorus antioxidants), sulfur compounds (sulfur antioxidants) and the like can be mentioned.

  Examples of the phenol compound include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-p-ethylphenol, stearyl-β- (3, Monophenols such as 5-di-t-butyl-4-hydroxyphenyl) propionate; 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6) -T-butylphenol), 4,4'-thiobis (3-methyl-6-t-butylphenol), 4,4'-butylidenebis (3-methyl-6-t-butylphenol), 3,9-bis [1, 1-dimethyl-2- {β- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} ethyl] 2,4,8,10-tetraoxas Bisphenols such as pyro [5.5] undecane; 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6 -Tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis [methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, bis [3,3′-bis- (4′-hydroxy-3′-t-butylphenyl) butyric acid] glycol ester, 1,3,5-tris (3 ′, 5′-di-t-butyl-4 '-Hydroxybenzyl) -s-triazine-2,4,6- (1H, 3H, 5H) trione, polymer type phenols such as tocophenol, and the like.

  Examples of the hindered amine compound include bis (1,2,2,6,6-pentamethyl-4-piperidyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl]. Butyl malonate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, methyl-1,2,2,6,6-pentamethyl-4-piperidyl sebacate, 4-benzoyloxy-2 2,6,6-tetramethylpiperidine and the like.

  Examples of the phosphorus compound include triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, tris (nonylphenyl) phosphite, diisodecylpentaerythritol phosphite, tris (2,4-di-t-butyl). Phenyl) phosphite, cyclic neopentanetetraylbis (octadecyl) phosphite, cyclic neopentanetetraylbis (2,4-di-t-butylphenyl) phosphite, cyclic neopentanetetraylbis (2, Phosphites such as 4-di-t-butyl-4-methylphenyl) phosphite, bis [2-tert-butyl-6-methyl-4- {2- (octadecyloxycarbonyl) ethyl} phenyl] hydrogen phosphite Class; 9,10-di Dro-9-oxa-10-phosphaphenanthrene-10-oxide, 10- (3,5-di-t-butyl-4-hydroxybenzyl) -9,10-dihydro-9-oxa-10-phosphaphenanthrene Examples include oxaphosphaphenanthrene oxides such as -10-oxide.

  Examples of the sulfur compound include dodecanethiol, dilauryl-3,3′-thiodipropionate, dimyristyl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, and the like. Can be mentioned.

  In addition, in the said photocationic polymerizable composition, antioxidant can also be used individually by 1 type and can also be used in combination of 2 or more type. Moreover, as said antioxidant, commercial items, such as a brand name "IRGANOX1010" (made by BASF, a phenolic compound), a brand name "IRGAFOS168" (made by BASF, a phosphorus compound), can also be used, for example.

  Among them, the antioxidant is preferably a phenol compound, a phosphorus compound, or a sulfur compound, and particularly, a combination of a phenol compound and a phosphorus compound or a sulfur compound (particularly, a phenol compound and a sulfur compound). In combination).

  The content (blending amount) of the antioxidant in the photocationically polymerizable composition is not particularly limited, but is 0.1 to 10% by weight with respect to the total amount (100% by weight) of the photocationically polymerizable composition. Preferably, it is 0.1 to 5% by weight, more preferably 0.1 to 3% by weight. When the content of the antioxidant is out of the above range, the optical properties of the polymer optical fiber tend to be impaired. In particular, when the content of the antioxidant is less than 0.1% by weight, the polymer optical fiber is thermally deteriorated due to high-temperature treatment such as solder reflow treatment, optical loss increases, or the shape of the end face changes (protrusion, etc.). May be likely to occur. In addition, when using 2 or more types of antioxidant together, it is preferable that these total amounts are controlled by the said range.

  In particular, when a phenol compound and a phosphorus compound or sulfur compound are used in combination as the antioxidant, the ratio of these contents (blending amount) [phenol compound / phosphorus compound or sulfur compound] (weight) The ratio is not particularly limited, but is preferably 0.1 / 1 to 20/1, more preferably 0.5 / 1 to 15/1, still more preferably 1/1 to 10/1, particularly preferably 2 /. 1 to 5/1. There is a tendency that the heat resistance of the polymer optical fiber can be remarkably improved by controlling the ratio within the above range.

  The said cationic photopolymerizable composition may contain the other additive as needed within the range which does not impair the effect of this invention. Other additives include, for example, curing-expandable monomers, photosensitizers (anthracene sensitizers, etc.), resins, adhesion improvers, reinforcing agents, softeners, plasticizers, viscosity modifiers, solvents, inorganic Or well-known thru | or usual various additives, such as organic particle | grains (nanoscale particle | grains etc.) and fluorosilane, are mentioned.

(Photoradical polymerizable composition)
Examples of the radical photopolymerizable composition include a composition containing a radical polymerizable compound as an essential component and, if necessary, a radical photopolymerization initiator. The radical polymerizable compound is a compound having one or more radical polymerizable groups in the molecule. Examples of the radical polymerizable group include (meth) acryloyl group, (meth) acryloyloxy group, (meth) acryloylamino group, vinylaryl group, vinyl ether group, vinyloxycarbonyl group and the like. In the radical photopolymerizable composition, the radical polymerizable compound can be used alone or in combination of two or more.

  The radical polymerizable compound is not particularly limited as long as it is a compound having one or more radical polymerizable groups in the molecule. For example, urethane (meth) acrylate, polyester (meth) acrylate, polyacryl (meth) ) Acrylate, epoxy (meth) acrylate, polyether (meth) acrylate, polyfunctional (meth) acrylate other than these, and the like.

  The urethane (meth) acrylate may be a known or commonly used urethane (meth) acrylate [compound having a urethane bond and (meth) acryloyl group in the molecule], and is not particularly limited. Urethane (meth) acrylate obtained by reacting an isocyanate compound (polyisocyanate) having two or more isocyanate groups in the compound with a compound having active hydrogen atoms and (meth) acryloyl groups in the molecule; urethane prepolymer ( For example, a urethane prepolymer having one or more isocyanate groups in the molecule obtained by reaction of a polyisocyanate and a compound having two or more hydroxyl groups in the molecule (polyol), an active hydrogen atom in the molecule and ( By reacting with a compound having a (meth) acryloyl group Urethane (meth) acrylate and the like to be.

  The polyisocyanate as a raw material for the urethane (meth) acrylate is not particularly limited as long as it is a compound having two or more isocyanate groups in the molecule. For example, aliphatic polyisocyanate [for example, tetramethylene diisocyanate Aliphatic diisocyanates such as hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMDI), lysine diisocyanate (LDI); 1,6,11-undecane triisocyanate methyloctane, 1,3,6-hexamethylene triisocyanate, etc. Aliphatic triisocyanates, etc.], alicyclic polyisocyanates [for example, cyclohexane 1,4-diisocyanate, isophorone diisocyanate (IPDI), hydrogenated xylylene diisocyanate Alicyclic diisocyanates such as hydrogenated bis (isocyanatophenyl) methane; alicyclic triisocyanates such as bicycloheptane triisocyanate], aromatic polyisocyanates [eg, phenylene diisocyanate, tolylene diisocyanate (TDI), xylylene Diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), naphthalene diisocyanate (NDI), bis (isocyanatophenyl) methane (MDI), toluidine diisocyanate (TODI), 1,3-bis (isocyanatophenyl) propane, etc. Aromatic triisocyanates such as triphenylmethane triisocyanate], heterocyclic polyisocyanates, and derivatives of these polyisocyanates [for example, Reisocyanate dimer, trimer, biuret, allophanate, polyisocyanate having 2,4,6-oxadiazinetrione ring (polymer of carbon dioxide and polyisocyanate (monomer)), carbodiimide, uretdione, etc. It is done. In addition, the said polyisocyanate can also be used individually by 1 type, and can also be used in combination of 2 or more type.

The polyol as a raw material of the urethane (meth) acrylate is not particularly limited. For example, a low molecular weight polyol [aliphatic polyol (C _2-10 alkanediol such as ethylene glycol, propylene glycol, tetramethylene ether glycol; glycerin) _C3-12 aliphatic polyols such as trimethylolpropane and pentaerythritol), alicyclic polyols (cycloalkanediols such as 1,4-cyclohexanediol), hydrogenated bisphenols such as hydrogenated bisphenol A, etc. C _2-4 alkylene oxide adducts, etc.), aromatic polyols (araliphatic diols such as xylylene glycol, bisphenols such as bisphenol A, S, F, etc., these C _2-4 alkylene oxide adducts, etc.)] , Polymer polio S [e.g., polyether polyols (polyethylene glycol, polypropylene glycol, poly C _2-4 alkylene glycol such as polytetramethylene ether glycol), polyester polyols (e.g., such as polyester polyols and aliphatic dicarboxylic acids and aliphatic diols) , Polycarbonate polyol, etc.]. In addition, the said compound can also be used individually by 1 type, and can also be used in combination of 2 or more type.

  Although it does not specifically limit as a compound which has an active hydrogen atom and a (meth) acryloyl group in the said molecule | numerator as a raw material of the said urethane (meth) acrylate, For example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl ( (Meth) acrylate, 4-hydroxycyclohexyl (meth) acrylate, 5-hydroxycyclooctyl (meth) acrylate, 2-hydroxy-3-phenyloxypropyl (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta ( And (meth) acrylate. In addition, the said compound can also be used individually by 1 type, and can also be used in combination of 2 or more type.

  The urethane prepolymer as a raw material of the urethane (meth) acrylate is not particularly limited, but is a multimer of the polyisocyanate described above, a bullet-modified multimer of the polyisocyanate described above, and an adduct of the polyisocyanate and the polyol described above. And a polyurethane prepolymer obtained by reacting an excess amount of the polyisocyanate with respect to the polyol and the polyol. In addition, the said urethane prepolymer can also be used individually by 1 type, and can also be used in combination of 2 or more type.

  The polyester (meth) acrylate may be a known or commonly used polyester (meth) acrylate [compound having an ester bond and (meth) acryloyl group in the molecule], and is not particularly limited. (Or derivatives thereof) and polyesters such as polymers or oligomers obtained by polymerizing polycarboxylic acids (or derivatives thereof) and polymers or oligomers obtained by ring-opening polymerization of cyclic ester compounds. Examples thereof include polyester (meth) acrylates obtained by reacting a compound having a (meth) acryloyl group (for example, (meth) acrylic acid, hydroxyalkyl (meth) acrylate) and the like.

  It does not specifically limit as said polyol as a raw material of the said polyester (meth) acrylate, For example, the thing similar to the polyol as a raw material of the said urethane (meth) acrylate, etc. are mentioned. In addition, the said polyol or its derivative can also be used individually by 1 type, and can also be used in combination of 2 or more type.

  The polycarboxylic acid as a raw material for the polyester (meth) acrylate is not particularly limited, but examples thereof include saturated polycarboxylic acids such as adipic acid, succinic acid, and sebacic acid; maleic acid, fumaric acid, itaconic acid, citraconic acid And unsaturated polycarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid and trimellitic acid. In addition, the said polycarboxylic acid or its derivative can also be used individually by 1 type, and can also be used in combination of 2 or more type.

  The cyclic ester compound as a raw material for the polyester (meth) acrylate is not particularly limited, and examples thereof include lactone compounds such as ε-caprolactone, δ-valerolactone, γ-butyrolactone, and γ-valerolactone, or derivatives thereof. Can be mentioned. In addition, the said cyclic ester compound can also be used individually by 1 type, and can also be used in combination of 2 or more type.

  As said polyacryl (meth) acrylate, well-known thru | or usual polyacryl (meth) acrylate [The acryl oligomer or polymer which has a (meth) acryloyl group in a molecule | numerator] can be used, Although it does not specifically limit, For example, The (meth) acryloyl group in the molecule such as (meth) acrylic acid is added to the epoxy group of an acrylic polymer having an epoxy group (for example, a copolymer of (meth) acrylic monomer and glycidyl (meth) acrylate). Examples thereof include polyacryl (meth) acrylate obtained by addition reaction of the compound having the same.

  The epoxy (meth) acrylate is a known or commonly used epoxy (meth) acrylate [epoxy (meth) obtained by reaction of an epoxy compound with a compound having an addition-reactive group and a (meth) acryloyl group for the epoxy group. Acrylate] can be used, and is not particularly limited. For example, a compound having two or more epoxy groups in the molecule (for example, polyhydric alcohol type, polyvalent carboxylic acid type, bisphenol A, F, S, etc. Epoxy (meth) acrylate obtained by addition reaction of a compound having a (meth) acryloyl group in a molecule such as (meth) acrylic acid to the epoxy group of an epoxy resin of a bisphenol type or a novolak type) Can be mentioned.

  As the polyether (meth) acrylate, known or commonly used polyether (meth) acrylate [compound having an ether bond and (meth) acryloyl group in the molecule] can be used, and is not particularly limited. , Diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate , Polytetramethylene glycol di (meth) acrylate, bisphenol A alkylene oxide (for example, ethylene oxide, propylene oxide, etc.) adducts with one or both ends of (meth) acrylate Polyether (meth) acrylate having Royle group.

  As said polyfunctional (meth) acrylate, well-known thru | or usual polyfunctional (meth) acrylate [The compound which has a 2 or more (meth) acryloyl group in a molecule | numerator] can be used, Although it does not specifically limit, For example, 2-hydroxy-3- (meth) acryloyloxypropyl (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, 1,6-hexanediol di (meth) Acrylate, 1,9-nonanediol di (meth) acrylate, ethoxylated isocyanuric acid tri (meth) acrylate, ε-caprolactone modified tris (2- (meth) acryloyloxyethyl) isocyanurate, glycerin di (meth) acrylate, ethoxy Glycerin tri (meth) acrylate , Pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, ethoxylated pentaerythritol tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol poly (Meth) acrylate, ethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, polybutadiene (meth) acrylate, melamine (meth) acrylate, polyacetal (meta ) Acrylate, 9,9-bis [4- (2- (meth) acryloyloxyethoxy) phenyl] fluorene, 2,2-bis [4-((meth) acryloylo) Xydiethoxy) phenyl] propane and the like.

As the above-mentioned radical polymerizable compound, in addition, the oxetane ring-containing (meth) acrylic acid ester compound represented by the formula (1) alone or with other compounds having other cationic polymerizable properties (other cationic polymerizable compounds) A radical polymerizable resin (radical polymerizable polymer) obtained by cationic polymerization can also be used. That is, as the photoradical polymerizable composition, a photocurable resin composition (photoradical polymerizable resin composition) containing the radical polymerizable resin as an essential component can also be used. The above radical-polymerizable resin is a polymer having a CH ₂ = CR ¹ CO- groups derived from oxetane ring-containing (meth) acrylic acid ester compound represented by the formula (1) in the molecule.

  The radical polymerizable resin is obtained by cationic polymerization of the oxetane ring-containing (meth) acrylic acid ester compound represented by the formula (1) alone or together with other cationic polymerizable compounds.

［式中、Ｒ¹、Ｒ²、Ａは上記に同じ。］ The oxetane ring-containing (meth) acrylic acid ester compound represented by the formula (1) has an oxetane ring that is a cationic polymerization site and a (meth) acryloyl group that is a radical polymerization site in the molecule, and therefore is cationic polymerization alone. Or a radically polymerizable resin having a structural unit represented by the following formula (repeating structural unit) by cation copolymerization with other cationically polymerizable compounds. The cationic copolymer includes block copolymerization, random copolymerization and the like.

[Wherein R ¹ , R ² and A are the same as above. ]

  Among the above radical polymerizable resins, an oxetane ring-containing (meth) acrylic acid ester compound represented by the formula (1) and other cationic polymerizable compounds are particularly preferable in that a polymer optical fiber having excellent flexibility can be formed. A radically polymerizable resin obtained by cationic copolymerization of is preferred. In particular, the proportion of the oxetane ring-containing (meth) acrylic acid ester compound represented by the formula (1) in all monomers constituting the radical polymerizable resin is 0.1% by weight or more (preferably 1 to 99% by weight). In particular, a resin obtained by cationic copolymerization at a ratio of 10 to 80% by weight) is preferable.

  Examples of the other cationically polymerizable compound include one or more cationically polymerizable groups such as oxetane ring, epoxy ring, vinyl ether group, and vinylaryl group exemplified in the section of the photocationically polymerizable composition in the molecule. And the like.

  The other cationic polymerizable compound is selected from the group consisting of an oxetane ring, an epoxy ring, a vinyl ether group, and a vinyl aryl group in the molecule, in that a cured product having excellent flexibility and heat resistance can be formed. Further, compounds having only one cationic polymerizable group are preferable, and in particular, trimethylene oxide, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, 3-ethyl-3-[(phenoxy) methyl] oxetane, 3 -Compounds having only one oxetane ring in the molecule such as ethyl-3- (hexyloxymethyl) oxetane, compounds having only one epoxy group in the molecule such as glycidyl methyl ether and butyric acid (R) -glycidyl, etc. preferable. One of these other cationic polymerizable compounds can be used alone, or two or more of them can be used in combination.

  The radical polymerizable resin can be produced by a known or commonly used method (for example, cationic polymerization reaction), and the production method is not particularly limited. For example, the method described in International Publication No. 2011/129268 is used. Can be manufactured.

  Although the weight average molecular weight of the said radical polymerizable resin is not specifically limited, 500 or more (for example, about 500-1 million) are preferable, More preferably, it is 3000-500,000. When the weight average molecular weight of the radical polymerizable resin is below the above range, the flexibility of the polymer optical fiber tends to be lowered.

  Although the number average molecular weight of the said radical polymerizable resin is not specifically limited, 100 or more (for example, 100-500,000) are preferable, More preferably, it is 300-250,000. If the number average molecular weight of the radical polymerizable resin is out of the above range, the flexibility of the polymer optical fiber tends to be difficult to obtain. In addition, the weight average molecular weight and number average molecular weight of the said radical polymerizable resin can be measured as a value of standard polystyrene conversion by GPC (gel permeation chromatography) method, for example.

  In the said radical photopolymerizable composition, the oxetane ring containing (meth) acrylic acid ester compound represented by Formula (1) can also be used as a radically polymerizable compound. Moreover, the radical polymerizable compound etc. which were illustrated by the term of the said photocationic polymerizable composition can also be used as a radical polymerizable compound.

  The content (blending amount) of the radically polymerizable compound in the photoradical polymerizable composition is not particularly limited, but is 40% by weight or more and 100% by weight with respect to the total amount (100% by weight) of the photoradical polymerizable composition. % Is preferred, more preferably 60 to 99% by weight.

  The said radical photopolymerizable composition may contain radical photopolymerization initiator as needed. Examples of the photo radical polymerization initiator include benzophenone, acetophenone, benzyl, benzyldimethylketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, dimethoxyacetophenone, dimethoxyphenylacetophenone, diethoxyacetophenone, diphenyl disulfite. 1-hydroxycyclohexyl phenyl ketone and the like. The said radical photopolymerization initiator can also be used individually by 1 type, and can also be used in combination of 2 or more type.

  The photoradical polymerizable composition may contain a synergist for enhancing the conversion of light absorption energy into polymerization initiation free radicals. Examples of the synergist include amines such as triethylamine, diethylamine, diethanolamine, ethanolamine, dimethylaminobenzoic acid and methyl dimethylaminobenzoate; ketones such as thioxanthone, 2-isopropylthioxanthone, 2,4-diethylthioxanthone, and acetylacetone. Is mentioned.

  When the radical photopolymerizable composition contains a polymerization initiator, the content (blending amount) of the radically polymerizable compound in the radical photopolymerizable composition (for example, radical polymerizable resin and other components) The total weight of the radical polymerizable compound) is preferably from 0.01 to 50 parts by weight, more preferably from 0.1 to 20 parts by weight, based on 100 parts by weight.

  The photoradical polymerizable composition may contain an antioxidant. In particular, when the photo-radical polymerizable composition is used as a curable composition for forming a core or a curable composition for forming a cladding, any one of the curable composition for forming a core and the curable composition for forming a cladding. One or both preferably contain an antioxidant. Examples of the antioxidant include known and commonly used antioxidants, and are not particularly limited. Examples thereof include those similar to those exemplified in the section of the photocationically polymerizable composition. Among them, the antioxidant is preferably a phenol compound, a phosphorus compound, or a sulfur compound, and particularly, a combination of a phenol compound and a phosphorus compound or a sulfur compound (particularly, a phenol compound and a sulfur compound). In combination).

  The content (blending amount) of the antioxidant in the photoradical polymerizable composition is not particularly limited, but is 0.1 to 10 wt% with respect to the total amount (100 wt%) of the photoradical polymerizable composition. Preferably, it is 0.1 to 5% by weight, more preferably 0.1 to 3% by weight. When the content of the antioxidant is out of the above range, the optical properties of the polymer optical fiber tend to be impaired. In particular, when the content of the antioxidant is less than 0.1% by weight, the polymer optical fiber is thermally deteriorated due to high-temperature treatment such as solder reflow treatment, optical loss increases, or the shape of the end face changes (protrusion, etc.). May be likely to occur. In addition, when using 2 or more types of antioxidant together, it is preferable that these total amounts are controlled by the said range.

  In particular, when a phenol compound and a phosphorus compound or sulfur compound are used in combination as the antioxidant, the ratio of these contents (blending amount) [phenol compound / phosphorus compound or sulfur compound] (weight) The ratio is not particularly limited, but is preferably 0.1 / 1 to 20/1, more preferably 0.5 / 1 to 15/1, still more preferably 1/1 to 10/1, particularly preferably 2 /. 1 to 5/1. There is a tendency that the heat resistance of the polymer optical fiber can be remarkably improved by controlling the ratio within the above range.

  The said radical photopolymerizable composition may contain the other additive as needed within the range which does not impair the effect of this invention. Other additives include known or commonly used additives, and are not particularly limited. Examples thereof include those similar to those exemplified in the section of the photocationically polymerizable composition.

  The polymer optical fiber of the present invention is manufactured by a known or conventional method for forming a polymer optical fiber having a core-clad structure using a photocurable composition as long as the thickness of the clad is controlled to 1 to 20 μm. Can do. In particular, the polymer optical fiber of the present invention comprises a core-forming curable composition and a cladding-forming curable composition in a form corresponding to the form of the core and clad of the polymer optical fiber using a nozzle (fiber Core-forming curable composition discharged in a concentrically surrounded by a cylindrical clad-forming curable composition), and simultaneously ejected coaxially into a fiber and then cured for core formation It is preferable to manufacture by the manufacturing method which hardens a curable composition and the curable composition for clad formation by light irradiation. The polymer optical fiber manufactured by the manufacturing method has high reliability because the central axes of the core and the clad coincide with each other with high accuracy.

Specific examples of the production method include the following production methods (referred to as “the production method of the polymer optical fiber of the present invention”). The polymer optical fiber produced by the method for producing a polymer optical fiber of the present invention can further reduce minute foreign matters to a high degree and is excellent in productivity.
Production method of polymer optical fiber of the present invention: curable composition for core formation and curable composition for clad formation using a nozzle having a multiple structure of three or more layers (sometimes referred to as “multi-tube nozzle”) And a resin composition for the outermost layer are simultaneously (integrated) from the discharge port of the multi-tube nozzle, and are coaxial (the core-forming curable composition discharged in the form of a fiber is a cylindrical cladding-forming curing) The outermost layer resin composition is located in the outermost layer, with the curable composition being concentrically surrounded by the adhesive composition and the curable composition being concentrically surrounded by the cylindrical outermost layer resin composition). In this way, the outermost resin composition is not cured, and the core-forming curable composition and the cladding-forming curable composition are cured to form a polymer material (core Hardness of the curable composition for forming And a polymer material (cured product of a curable composition for forming a clad) (referred to as “process A”); after the process A, the outermost resin composition is removed. And a step (referred to as “step B”) for producing a polymer optical fiber, which is an essential step. In addition, the manufacturing method of the polymeric optical fiber of this invention may include processes (for example, below-mentioned process C etc.) other than the process A and the process B. In the method for producing an optical fiber of the present invention, the composition (core-forming curable composition, clad-forming curable composition, and outermost-layer resin composition) discharged in the above-described fiber shape is used as “high”. It may be referred to as “molecular optical fiber forming composition”.

<Process A>
FIG. 2 is a schematic view (cross-sectional view) showing an example of step A in the method for producing a polymer optical fiber of the present invention. 2 in FIG. 2 indicates a multi-tube nozzle. In step A, first, using the multi-tube nozzle 1, the core-forming curable composition 20, the clad-forming curable composition 30, and the outermost layer resin composition 40 are discharged from the multi-tube nozzle 1 discharge port. At the same time, the resin composition 40 for outermost layer is coaxially ejected in a fiber shape so as to be located in the outermost layer. Thereafter, the outermost layer resin composition 40 of the polymer optical fiber forming composition 10 that hangs down from the discharge port of the multi-tube nozzle 1 and is formed in a fiber shape is not cured, and the core-forming curable composition 20 and The core and the clad are simultaneously formed by curing the clad forming curable composition 30 and converting it into each polymer material. As a result, a polymer optical fiber (structure having a resin composition for outermost layer and a polymer optical fiber) 100 coated with the resin composition for outermost layer is obtained. In addition, the block arrow drawn with the dotted line in FIG. 2 shows operation (namely, light irradiation) for hardening the curable composition 20 for core formation, and the curable composition 30 for clad formation.

[Multi-tube nozzle]
The multi-tube nozzle used in step A has a core-forming curable composition, a cladding-forming curable composition, and a resin composition for the outermost layer passed therethrough, and these compositions are used for core formation. The curable composition is coated with a curable composition for forming a clad, and further, the curable composition for forming a clad is coated with a resin composition for an outermost layer, and the resin composition for an outermost layer is located in the outermost layer. In the state (form) (form corresponding to the form in which the polymer optical fiber is coated with the resin composition for the outermost layer), it is a structure that can be ejected in a fiber form from its ejection port. That is, the multi-tube nozzle is a nozzle having a triple structure of triple or more. More specifically, the multi-tube nozzle includes an inner tube, an outer tube (first outer tube) positioned outside the inner tube, and the outer tube as a structure at least near the discharge port and the discharge port. This is a nozzle having a triple (multilayer) structure having at least a triple pipe having at least an outer pipe (second outer pipe) positioned on the outer side of the (first outer pipe). In the present specification, the innermost tube in the multiple tube nozzle is referred to as an “inner tube”, and a tube located outside the inner tube is referred to as an “outer tube”. Further, among the outer tubes in the multi-tube nozzle, the one closest to the inner tube is referred to as a “first outer tube”, and in order toward the outside, “second outer tube”, “third outer tube”,. -It shall call a "(n-1) outer pipe" and an "nth outer pipe" (n shows an integer greater than or equal to 2).

  The multi-tube nozzle includes an inner tube, between the inner tube and the first outer tube, between the first outer tube and the second outer tube, ..., (n-1) outer tube and nth outer tube. The core-forming curable composition, the clad-forming curable composition, and the outermost-layer resin composition can be allowed to pass therethrough, and these are simultaneously (together), coaxially, and the discharge port. It can be discharged from. In the method for producing a polymer optical fiber of the present invention, the outermost resin composition is passed between the (n-1) outer tube and the nth outer tube (outermost outer tube). For example, when the multiple tube nozzle is a triple tube nozzle having a triple structure (a multiple tube nozzle having an inner tube, a first outer tube, and a second outer tube) (see, for example, FIG. 2), the inner tube A core-forming curable composition, a clad-forming curable composition between the inner tube and the first outer tube, and an outermost layer resin composition between the first outer tube and the second outer tube. By passing the liquid, each composition can be simultaneously discharged from the discharge port.

  The multi-tube nozzle usually has an inlet for introducing the core-forming curable composition, the clad-forming curable composition, and the outermost layer resin composition into the multi-tube nozzle. For example, the introduction port is connected to a tank, a metering pump, or the like for storing each of the above-described compositions via an appropriate tube as necessary. The size, shape, position, etc. of the inlet are not particularly limited.

  The shape of each tube (inner tube, outer tube) in the multi-tube nozzle is such that the core-forming curable composition, the cladding-forming curable composition, and the outermost-layer resin composition can be passed through it. There is no particular limitation, and examples thereof include a cylindrical shape (hollow column shape; cylindrical shape, rectangular tube shape, etc.). Among these, from the viewpoint of producing a polymer optical fiber having a low propagation loss, the shape of the tube through which at least the curable composition for core formation and the curable composition for clad formation pass is preferably cylindrical.

  The material of each tube (inner tube, outer tube) in the multiple tube nozzle is not particularly limited, and examples thereof include SUS, aluminum, and resin. Among these, SUS is preferable from the viewpoint of durability and strength.

  FIG. 3 is a schematic view showing an example of a multi-tube nozzle (in the case of a triple tube nozzle; cross-sectional view in the longitudinal direction of the tube). In FIG. 3, 1a of the multiple tube nozzle 1 is an inner tube, 1b is a first outer tube, and 1c is a second outer tube. In addition, 1d of the multi-tube nozzle 1 represents a discharge port, and 1e to 1g represent introduction ports for the respective compositions. By using such a multi-tube nozzle, the core-forming curable composition is multiplexed from the inlet 1e, the clad-forming curable composition is introduced from the inlet 1f, and the outermost layer resin composition is multiplexed from the inlet 1g. Since these compositions can be introduced into the inside of the tube nozzle 1 and discharged simultaneously from the discharge port 1d in a form corresponding to the form of the polymer optical fiber coated with the outermost layer resin composition, By curing the curable composition for forming a core and the curable composition for forming a clad in these compositions, the polymer optical fiber in which the central axes of the core and the clad are accurately aligned is coated with the resin composition for the outermost layer. A structure is obtained.

  The diameter (inner diameter and outer diameter) of each pipe (inner pipe and outer pipe) in the multi-pipe nozzle is not particularly limited. Specifically, for example, the inner pipe when the multi-pipe nozzle is a triple pipe nozzle is used. The inner diameter (the inner diameter at the discharge port) is preferably, for example, 0.1 to 4.0 mm, and the outer diameter (the outer diameter at the discharge port) of the inner tube is preferably, for example, 0.4 to 4.6 mm. In this case, the inner diameter of the first outer tube (inner diameter at the discharge port) is preferably, for example, 0.8 to 6.6 mm, and the outer diameter of the first outer tube (outer diameter at the discharge port) is, for example, 1.1 to 7.2 mm is preferable. In this case, the inner diameter of the second outer tube (the inner diameter at the discharge port) is preferably, for example, 1.5 to 11.2 mm. However, the diameter of each tube in the multi-tube nozzle is not limited to the above range. For example, the diameter of the core, the diameter of the clad, the viscosity of each composition, the discharge speed, the draft ratio ( Average discharge linear velocity of the polymer optical fiber forming composition, and the take-up speed of the structure obtained by curing of the core forming curable composition and the clad forming curable composition in the polymer optical fiber forming composition The ratio can be selected appropriately according to (for example, the ratio to the winding speed).

  In addition, it is preferable that the center axis | shaft of each pipe | tube agree | coincides in the said multiple tube nozzle at least in the discharge port (tip part at the discharge port side). By using such a multi-tube nozzle, a polymer optical fiber in which the central axis of the core and the central axis of the cladding coincide can be easily manufactured. Thus, the polymer optical fibers having the same central axis can exhibit high reliability when connecting the polymer optical fibers or connecting them to other devices (for example, connectors, light source devices, etc.).

  The multi-tube nozzle preferably has an adjustment mechanism (sometimes referred to as a “position adjustment mechanism”) for adjusting the position of each tube in order to align the central axes of the tubes. The position adjusting mechanism is not particularly limited as long as the position of each pipe can be adjusted. Specifically, for example, a screw (adjustment screw) arranged so as to penetrate at least the outer tube located on the outermost side and bring the tip into contact with the outer surface of each tube located on the inner side of the outer tube. It can be used as a simple position adjustment mechanism. FIG. 4 is a schematic diagram (cross-sectional view in the radial direction of the tube) showing an example of a multi-tube nozzle provided with a position adjusting mechanism. In FIG. 4, 1h represents an adjusting screw. In FIG. 4, the position adjusting mechanism is configured by bringing the tips of six adjusting screws 1h into contact with the inner tube 1a or the first outer tube 1b at equal intervals, and the screwing condition of these adjusting screws. Can be adjusted to adjust the position of the inner tube 1a or the first outer tube 1b inside the second outer tube 1c. However, the size, number, and arrangement of the adjusting screws used are not limited to this. Moreover, the adjustment mechanism of the position of each pipe | tube is not limited to the position adjustment mechanism shown in FIG.

  The multiple tube nozzle is not limited to the triple tube nozzle described above, and may be a nozzle having a multiple tube structure of four or more. The multi-tube nozzle can be appropriately selected according to the structure and shape of the polymer optical fiber to be manufactured.

[Curable composition for core formation, curable composition for clad formation]
The photocurable composition as the core-forming curable composition and the photocurable composition as the cladding-forming curable composition in the method for producing a polymer optical fiber of the present invention are not particularly limited, but both are room temperature. It is preferably liquid at (about 25 ° C.). That is, it is preferable that both are liquid materials having fluidity at room temperature. By using a liquid photocurable composition as the core-forming curable composition and the clad-forming curable composition, spinning at room temperature is possible without reducing the viscosity by heating or using a solvent. Furthermore, since impurities such as fine foreign substances in the photocurable composition can be easily removed by filtration, it is easy to obtain a high-quality polymer optical fiber. On the other hand, when a composition (resin composition) that is solid at room temperature is used as a raw material for a polymer optical fiber, spinning at room temperature is difficult unless the viscosity is lowered by heating or the use of a solvent. Disadvantageous. In general, a composition (resin composition) that is solid at room temperature tends to have a complicated operation for removing impurities such as fine foreign matters.

  In particular, the viscosity at 25 ° C. of the core-forming curable composition is not particularly limited, but it is 25000 mPa · s or less (for example, in terms of easy removal of impurities by filtration and easy to obtain a low optical loss polymer optical fiber) 20 to 25000 mPa · s) is preferable. Further, the viscosity at 25 ° C. of the curable composition for forming a clad is not particularly limited, but it is 10 to 25000 mPa · s in that it is easy to remove impurities by filtration and easily obtain a low optical loss polymer optical fiber. preferable. In particular, a photocurable composition having a viscosity at 25 ° C. of 10,000 mPa · s or less, which is very difficult to spin by a method that does not use the resin composition for the outermost layer, can be used as a curable composition for forming a clad. For example, compared with the method described in JP2012-159804A, the method for producing a polymer optical fiber of the present invention is very useful. The viscosity at 25 ° C. can be measured using an E-type viscometer (trade name “VISCONIC”, manufactured by Tokimec Co., Ltd.) (rotor: 1 ° 34 ′ × R24, rotation speed: 0.00). 5 rpm, measurement temperature: 25 ° C.). The viscosity of the photocurable composition can be controlled by, for example, the composition of the photocurable composition (for example, the molecular weight or content of the cationic polymerizable resin or radical polymerizable resin).

  Among these, as one or both (more preferably both) of the curable composition for core formation and the curable composition for clad formation in the method for producing a polymer optical fiber of the present invention, the optical loss of the polymer optical fiber is more reduced. In terms of reduction, it is preferable to use a photoradical polymerizable composition. In the method for producing a polymer optical fiber of the present invention, the outermost layer resin composition is used to coat the surface of the curable composition for forming a clad discharged from the nozzle with the outermost layer resin composition. Therefore, the radical polymerization reaction of the photopolymerizable composition as the curable composition for forming a clad is sufficiently advanced even in a special environment such as in the absence of oxygen (for example, in the air). be able to.

[Outermost layer resin composition]
The resin composition for the outermost layer used in the method for producing a polymer optical fiber of the present invention includes an outermost layer located outside the curable composition for core formation and the curable composition for clad formation discharged from the multi-tube nozzle. It is a composition for forming. In the method for producing a polymer optical fiber of the present invention, by adopting such a resin composition for the outermost layer, the curable composition for forming a clad can be shielded from the outside air, and curing inhibition by oxygen (polymerization inhibition) ) And other environmental problems can be prevented. For this reason, for example, a polymer optical fiber can be easily manufactured without using special equipment such as a nitrogen box. Further, since the curable composition for forming a clad does not come into contact with the outside air, the adhesion of foreign matters is prevented. Furthermore, since the spinnability can be ensured by adjusting the viscosity of the resin composition for the outermost layer, the freedom of material selection for the curable composition for clad formation is expanded. A composition having a low viscosity (for example, a composition having a viscosity of 10 to 10,000 mPa · s at 25 ° C.) can be used. From such a low-viscosity curable composition for forming a clad, fine foreign matters can be easily removed by filtration, so that a polymer optical fiber in which the fine foreign matters are highly reduced can be obtained. Furthermore, because the spinnability is ensured by the resin composition for the outermost layer described above, it becomes easy to reduce the thickness of the clad, so the core space factor is high and suitable for use as, for example, a light guide fiber bundle. The polymer optical fiber of the present invention can be easily produced.

  Since the resin composition for the outermost layer needs to be removed in the step B described in detail later, a resin composition that does not cure when the core-forming curable composition and the clad-forming curable composition are cured is used. This is very important. Generally, when a polymer material having a cross-linked structure is formed by curing, the polymer material has low solubility in a solvent, and thus it is difficult to remove the polymer material by washing using a solvent.

  Further, as the outermost layer resin composition, the core-forming curable composition and the clad-forming curable composition in Step A are used so as not to inhibit the curing of the core-forming curable composition and the clad-forming curable composition. It is necessary to use a composition that transmits light to be irradiated on the active composition. For example, when an ultraviolet curable composition is used as the curable composition for forming a core and the curable composition for forming a cladding, the outermost layer resin composition includes the curable composition for forming a core and the formation of a cladding. Therefore, it is necessary to use a composition that transmits the amount of ultraviolet light necessary to cure the curable composition.

  As the outermost resin composition, it is preferable to use a resin composition that can be discharged from a nozzle at room temperature, that is, a liquid that is liquid at room temperature (for example, 25 ° C.). Among them, from the viewpoint of improving the spinnability and facilitating the production of the polymer optical fiber, a liquid composition having a viscosity at 25 ° C. of 5000 mPa · s or more is preferable, and more preferably 10,000 to 500,000 mPa · s. . The viscosity at 25 ° C. can be measured using an E-type viscometer (trade name “VISCONIC”, manufactured by Tokimec Co., Ltd.) (rotor: 1 ° 34 ′ × R24, rotation speed: 0.00). 5 rpm, measurement temperature: 25 ° C.).

  The outermost layer resin composition is a composition that does not cure when the core-forming curable composition and the clad-forming curable composition are cured, and inhibits the polymerization reaction of each of the curable compositions. In addition, there can be used any one that can use a composition capable of imparting spinnability to the polymer optical fiber forming composition, and is not particularly limited. For example, polybutadiene rubber, water-soluble polymer (for example, , Polyvinyl alcohol, polyethylene glycol, and the like), and curable compositions that do not cure when the core-forming curable composition and the cladding-forming curable composition are cured. Examples of the latter curable composition include the above-described photocurable composition that does not cure by light irradiation and does not contain a polymerization initiator (for example, a photocationic polymerizable composition that initiates photocationic polymerization) And the like that do not contain an agent).

  The outermost resin composition is preferably one that can be removed by washing with any solvent in Step B. As the above-mentioned solvent, a solvent that is rich in the resin composition for the outermost layer and does not adversely affect the core and clad of the polymer optical fiber (for example, a solvent that does not dissolve or swell the core and clad or has poor solubility) ) Can be appropriately selected, and is not particularly limited. For example, water; aliphatic hydrocarbons such as hexane, heptane, and octane; alicyclic hydrocarbons such as cyclohexane; aromatics such as benzene, toluene, xylene, and ethylbenzene Hydrocarbons: Halogenated hydrocarbons such as chloroform, dichloromethane and 1,2-dichloroethane; Ethers such as diethyl ether, dimethoxyethane, tetrahydrofuran and dioxane; Ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; Methyl acetate, ethyl acetate and acetic acid Isopropyl, butyl acetate Cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate, esters such as propylene glycol monomethyl ether acetate (PGMEA); amides such as N, N-dimethylformamide, N, N-dimethylacetamide; acetonitrile, propionitrile, Nitriles such as benzonitrile; alcohols such as methanol, ethanol, isopropyl alcohol and butanol; dimethyl sulfoxide and the like. Of these, alcohols and esters (particularly acetates) are preferred.

[Discharge of polymer optical fiber forming composition]
As described above, the step A in the method for producing a polymer optical fiber according to the present invention uses a multi-tube nozzle to form a core-forming curable composition, a clad-forming curable composition, and an outermost layer resin composition. Are simultaneously and coaxially discharged from the outlet of the multi-tube nozzle in the form of a fiber so that the outermost resin composition is positioned in the outermost layer, and the outermost resin composition is not cured and the core In this step, the curable composition for forming and the curable composition for forming the clad are cured to simultaneously form the polymer material constituting the core and the polymer material constituting the clad. The polymer optical fiber forming composition discharged from the discharge port of the multi-tube nozzle is usually in the form of a fiber (thread-like) and corresponds to the form of the polymer optical fiber coated with the outermost layer resin composition (That is, a multiple structure of “core-forming curable composition (innermost) / cladding-curable curable composition / outermost-layer resin composition (outermost)”; in the radial cross section, the boundary of each composition And the outer surface of the resin composition for the outermost layer has a structure having a concentric shape).

  The discharge of the polymer optical fiber forming composition from the multi-tube nozzle in step A can be carried out at room temperature, or the inside of the multi-tube nozzle can be fixed depending on the type of each composition used. It can also be carried out while maintaining the temperature (for example, while heating or cooling). For example, the discharge may be performed while heating or cooling for the purpose of adjusting the viscosity. Heating and cooling can be performed using a known or conventional method or apparatus.

  Moreover, the discharge of the composition for forming a polymer optical fiber can be carried out in the air or in an inert gas atmosphere such as an argon atmosphere or a nitrogen atmosphere. In particular, in the method for producing a polymer optical fiber of the present invention, even when a photo-radical polymerizable composition is used as the curable composition for forming a cladding, the curing for forming a cladding is caused by the presence of the outermost resin composition. This is extremely useful in that polymer optical fibers can be produced in the air without using special equipment such as a nitrogen box because the composition is shielded from the outside air, thereby preventing polymerization inhibition by oxygen. is there.

  The discharge amount of each composition from the multi-tube nozzle can be appropriately adjusted according to the diameter of each tube in the multi-tube nozzle, the viscosity of each composition, the diameter of the polymer optical fiber to be produced, etc., and is not particularly limited. Generally, when the discharge amount of the core-forming curable composition and the clad-forming curable composition is increased, the wire diameter of the curable composition discharged from the multi-tube nozzle tends to be thickened. There is a tendency that the diameter of the polymer optical fiber to be obtained also becomes thick. In addition, by controlling the discharge amount of the core-forming curable composition and the clad-forming curable composition independently, the core diameter and the cladding diameter of the polymer optical fiber can be controlled independently. Become.

  The discharge rate (feed rate) of the polymer optical fiber forming composition (total amount) in step A is appropriately adjusted according to the diameter of each tube in the multi-tube nozzle, the viscosity of each composition, the diameter of the polymer optical fiber to be produced, and the like. Although it is possible and is not particularly limited, for example, 0.1 to 5.0 mL / min is preferable, and 0.3 to 1.5 mL / min is more preferable.

  The discharge rate of the core-forming curable composition is not particularly limited, but is preferably 0.01 to 0.20 mL / min, more preferably 0.05 to 0.15 mL / min. Although the discharge speed of a thing is not specifically limited, 0.01-1.00 mL / min is preferable, More preferably, it is 0.05-0.10 mL / min. The discharge rate of the outermost layer resin composition is not particularly limited, but is preferably 0.10 to 1.00 mL / min, more preferably 0.15 to 0.80 mL / min from the viewpoint of securing the spinnability. Minutes. The discharge rate can be appropriately controlled by known or conventional means such as the use of a metering pump.

[Curing of curable composition for core formation and curable composition for clad formation]
In step A, after the polymer optical fiber forming composition is discharged into a fiber shape using the multi-tube nozzle, a core forming curable composition and a clad forming curable composition among the polymer optical fiber forming compositions are used. By curing the composition, a polymer material constituting the core of the polymer optical fiber and a polymer material constituting the clad are simultaneously formed. At this time, as described above, the resin composition for the outermost layer is not cured. This is because it is necessary to remove the resin composition for the outermost layer in the subsequent step B. The curing means is not particularly limited as long as each of the curable compositions can be cured and converted into a polymer material. The curing is usually performed by light irradiation.

  The light applied to each of the curable compositions may be light that can cure the curable composition (particularly, light that can be cured by advancing the polymerization reaction of the photocurable composition). There is no particular limitation, and examples include ultraviolet rays, infrared rays, visible rays, and electron beams. Among these, ultraviolet rays are preferable from the viewpoint that a general photoinitiator can be used.

  The means for irradiating each curable composition with light is not particularly limited. For example, light (especially ultraviolet light) that can cure each curable composition is emitted (radiated) and each of the curable compositions is cured. A known or conventional light irradiation apparatus that can irradiate the conductive composition can be used. Specifically, for example, as a light irradiation device (ultraviolet irradiation device) that emits ultraviolet light, a light source such as a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a xenon lamp, a carbon arc, a metal halide lamp, sunlight, an LED lamp, or a laser. Can be used. Further, a light irradiation device that combines these light sources with a light guide for transmitting light output from the light sources, and a combination of these with various optical systems (for example, lenses, mirrors, etc.) Can be used as

FIG. 5 is a schematic view showing an embodiment of the process A. In the embodiment shown in FIG. 5, a multi-tube nozzle 1 and a light irradiation device 2 arranged so as to emit light below the discharge port at the tip of the multi-tube nozzle 1 are used. 5 includes a light source device 2c that outputs light, a light guide 2b that transmits the light, and a light guide tip 2a that emits light from an end (output end). . Note that the light irradiation device on the right side of FIG. 5 is drawn with a part of the light guide and the light source device omitted, but represents the same as the light irradiation device 2 on the left side, and the same applies to other drawings. Further, reference numerals 3a and 3b in FIG. 5 denote light-shielding members (3a: 3a: as means (control means) for controlling the irradiation intensity of light at the discharge port of the multi-tube nozzle 1 to 0.2 mW / cm ² or less, which will be described later. A light shielding cylinder, 3b: a light shielding plate).

  In the present specification, in particular, a portion that emits light in the light irradiation device may be referred to as an “emission portion”. For example, in the light irradiation device 2 shown in FIG. 5, the end portion (output end) of the tip portion 2a of the light guide is the emission portion.

  The method of irradiating light to each of the curable compositions is not particularly limited, and can be performed by a known or common method (light irradiation method). For example, when irradiating light using the said light irradiation apparatus, arrangement | positioning and the number of the output parts of the said light irradiation apparatus are not specifically limited. In particular, it is preferable to arrange the emission part of the light irradiation device so that the above-described curable composition can be irradiated with light uniformly. FIG. 6 is a schematic diagram (plan view) showing an example of a light irradiation device that can be used in step A, (a) is a light irradiation device that can irradiate light from three directions, and (b) is a light from two directions. It is the light irradiation device which can irradiate. The light irradiation apparatus shown in FIG. 6 is a light irradiation apparatus that emits light from three or two directions below the discharge port of the multi-tube nozzle and irradiates each of the curable compositions. The said light irradiation apparatus has the emission part (output end of the front-end | tip part 2a of a light guide) arrange | positioned at equal intervals with respect to each said curable composition at equal intervals. In FIG. 6, 4 represents a position through which the composition for forming a polymer optical fiber discharged from the multi-tube nozzle passes, and 2d and 2e are bases (supports) for fixing the tip portion 2a of the light guide of the light irradiation device. Body). However, a light irradiation apparatus is not limited to this, For example, what irradiates light from one direction or four or more directions may be sufficient. Further, the light irradiation device is not limited to one that emits light below the discharge port of the multi-tube nozzle, and may be one that emits light from above the discharge port of the multi-tube nozzle.

  Furthermore, since the said light irradiation apparatus irradiates light with respect to each said curable composition efficiently, you may use it in combination with a suitable optical system as needed. Specifically, for example, the light from the light irradiation device is condensed with a condensing lens (such as a convex lens or a cylindrical lens), and the curable composition is irradiated with higher intensity light, or once It is also possible to reflect the light irradiated to each curable composition by a mirror (reflection mirror) and irradiate each curable composition again. By using the optical system, it is possible to effectively use light and improve the productivity of the polymer optical fiber. The optical system is not limited to the above, and an optical system or the like that is usually used in a known or conventional optical device or the like can be used.

In step A, the irradiation intensity of the light applied to each of the curable compositions is not particularly limited. For example, the irradiation intensity for the polymer optical fiber forming composition is preferably 1000 to 5000 mW / cm ² , more preferably. 1500 to 2000 mW / cm ² . When the irradiation intensity is less than 1000 mW / cm ² , the core is particularly likely to be uncured, resulting in poor spinning, and the shape of the polymer optical fiber is likely to be deformed and difficult to handle. On the other hand, when the irradiation intensity exceeds 5000 mW / cm ² , it may be difficult to control the irradiation intensity of light at the discharge port of the multi-tube nozzle to 0.2 mW / cm ² or less.

In step A, in particular, the light irradiation intensity at the discharge port of the multi-tube nozzle (hereinafter sometimes simply referred to as “light irradiation intensity at the discharge port”) is controlled to 0.2 mW / cm ² or less. Is preferred. By controlling the irradiation intensity of light at the discharge port to 0.2 mW / cm ² or less, a polymer optical fiber having a uniform wire diameter can be obtained, and high productivity and high productivity without causing yarn breakage during production. There is a tendency to produce molecular optical fibers.

The “irradiation intensity of light at the discharge port” is exactly the same as in the production of a polymer optical fiber in the method for producing a polymer optical fiber of the present invention, except that the composition for forming a polymer optical fiber is not fed. Means the irradiation intensity (unit: mW / cm ² ) of light measured at the outlet of the multi-tube nozzle when light is emitted at (for example, when light is emitted from the light irradiation device). The method for measuring the irradiation intensity is not particularly limited. For example, the irradiation intensity can be measured with a light receiver UVD-S365 using a power meter (trade name “UV light meter UTI-250”, manufactured by USHIO INC.). it can.

The light irradiation intensity at the discharge port is not particularly limited, but is preferably 0.1 mW / cm ² or less from the viewpoint of obtaining a polymer optical fiber having a uniform wire diameter and preventing yarn breakage during production. When the irradiation intensity of light at the discharge port exceeds 0.2 mW / cm ² , a curing reaction (polymerization reaction) of each curable composition proceeds at the discharge port at the tip of the multi-tube nozzle, and a high temperature near the discharge port. In some cases, the viscosity of the composition for forming a molecular optical fiber fluctuates or becomes clogged. As a result, the fiber diameter of the polymer optical fiber forming composition discharged from the multi-tube nozzle is not stable, and a polymer optical fiber with a constant wire diameter cannot be obtained. Productivity may be reduced.

As a means for controlling the light irradiation intensity at the discharge port to 0.2 mW / cm ² or less, a known or conventional means can be applied, and is not particularly limited. For example, the control means exemplified below is used. Is possible.

  In particular, when a photocurable composition that is liquid at room temperature is used as the curable composition for forming a core and the curable composition for forming a clad in the method for producing a polymer optical fiber of the present invention, it is discharged from a multi-tube nozzle. It is necessary to irradiate the light at a relatively early stage where the formed photocurable composition can maintain a thread-like (fiber-like) shape and to convert (cured) it into a cured product. For this reason, in Step A, it is necessary to make the distance between the portion irradiated with light in the photocurable composition and the discharge port of the multi-tube nozzle as close as possible, and inevitably irradiate the photocurable composition. This makes it easy for the light to reach the vicinity of the discharge port of the multi-tube nozzle. From such a viewpoint, for example, as the control means, the spread of light is suppressed, or the shadow is formed on the discharge port by arranging it between the emission part of the light irradiation device and the discharge port of the multi-tube nozzle. It is effective to use the following light shielding member.

  FIG. 7A shows a cylindrical light shielding member 3a (sometimes referred to as a “light shielding cylinder”) as an example of the light shielding member. By covering the emission part of the light irradiation device (the output end of the light guide tip part 2a) with the light shielding cylinder 3a, it is possible to prevent the emitted light from spreading more than necessary and to propagate the light to the nozzle outlet. (Refer to FIG. 5, 3a in FIG. 5). The diameter, length, etc. of the light-shielding tube can be appropriately selected according to the shape of the emission part of the light irradiation device, and are not particularly limited.

  Further, as the light shielding member, a plate-shaped light shielding member (sometimes referred to as a “light shielding plate”) that can be disposed between the emission portion of the light irradiation device and the discharge port of the nozzle can be used (see FIG. 5, FIG. 5). 3b) in 5. By using such a light shielding plate, it is possible to block weak light that still leaks even when the light emitting device is covered with a light shielding tube. For this reason, it is effective to use the light shielding plate and the light shielding cylinder in combination. The shape and size of the light shielding plate are not particularly limited. For example, a disc-shaped light shielding plate shown in FIG. 7B or a conical light shielding plate shown in FIG. 7C is used. Can do. The light shielding plate preferably has a hole (3c in FIG. 7) for allowing the composition for forming a polymer optical fiber to pass from the viewpoint of ease of installation.

  The material forming the light shielding member such as the light shielding cylinder and the light shielding plate is not particularly limited. For example, SUS, aluminum, resin, paper, etc. can be used. The light shielding member is not particularly limited, but is preferably black from the viewpoint of preventing light reflection.

In step A, in particular, in order to obtain effects such as obtaining a polymer optical fiber with a uniform wire diameter and suppressing yarn breakage at a higher level, controlling the light irradiation angle to the curable composition. Is preferred. Specifically, in step A, a composition for forming a polymer optical fiber comprising the direction of light (maximum intensity light) having the maximum irradiation intensity among the light emitted from the light irradiation device and the curable composition. It is preferable to irradiate the composition for forming a polymer optical fiber with light so that the minimum value θ of the angle formed by the plane (plane) perpendicular to the discharge direction of the above satisfies the relationship of the following formula (I).
θ ≧ ψ / 2 (I)
In the above formula (I), ψ is the maximum value of the angles formed by the light beams whose irradiation intensity is 3% of the maximum value among the light beams emitted from the light irradiation device (sometimes referred to as “divergence angle”). It is.

  Strictly speaking, the light beam having the maximum irradiation intensity (sometimes referred to as “maximum intensity light”) out of the light beam emitted from the light irradiation device (the emission unit of the light irradiation device) is emitted from the emission unit. It can be specified by measuring the light intensity distribution of the light. In general, a light beam emitted to the front surface of the light emitting unit (for example, the output end of the light guide tip) is the maximum intensity light. Thus, for example, the tip portion of the light guide is at an angle θ with respect to a plane (usually a horizontal plane) perpendicular to the discharge direction of the polymer optical fiber forming composition (the discharge direction of the curable composition is also the same). The minimum value of the angle formed between the direction of the maximum intensity light and the plane perpendicular to the discharge direction of the composition for forming a polymer optical fiber by inclining only to the discharge direction side (for example, downward) of the composition for forming a polymer optical fiber Can be θ (see, for example, FIG. 9A).

  In the above formula (I), ψ is a light beam whose irradiation intensity is 3% of the maximum value (irradiation intensity of the maximum intensity light) out of the light beams emitted from the light irradiation device (the emission part of the light irradiation device). This is the maximum value (the spread angle) of the angle formed. However, when manufacturing the polymer optical fiber, when the emission part is covered with the above-described light shielding cylinder, the above-mentioned ψ means the spread angle of the light emitted from the emission part covered with the light shielding cylinder To do. In addition, it means that the directivity of the light radiate | emitted from a light irradiation apparatus is so high that the said divergence angle is small (narrow).

  FIG. 8 is a schematic diagram (a side view and a light shielding tube is used) for explaining the spread angle ψ of light emitted from the light irradiation device. In FIG. 8, 5a represents the maximum intensity light, and 5b represents a light beam whose irradiation intensity is 3% of the maximum intensity light. As shown in FIG. 8, the divergence angle ψ is defined by the maximum value 5c of the angle formed by the light beams whose irradiation intensity is 3% of the maximum intensity light. In general, the spread angle ψ tends to be small by covering the emitting portion with a light shielding tube.

  The above ψ can be derived, for example, by measuring the light intensity distribution at a certain distance (for example, 1.5 cm) from the emitting portion. The light intensity distribution can be measured by, for example, using an ultraviolet light quantity meter and moving the light receiver little by little from the center of irradiation light (the front of the center of the emitting portion) toward the peripheral portion.

In step A, the minimum value θ of the angle formed between the direction of the maximum intensity light emitted from the light irradiation device and the surface perpendicular to the discharge direction of the polymer optical fiber forming composition satisfies the relationship of the above formula (I). By controlling in such a manner, effects such as acquisition of a polymer optical fiber having a uniform wire diameter and suppression of yarn breakage during production can be obtained at a higher level. This is presumably due to the following reasons.
FIG. 9 is a schematic diagram (side view) illustrating the relationship between the minimum value θ of the angle formed by the direction of the maximum intensity light and the surface perpendicular to the discharge direction of the polymer optical fiber forming composition and the light spread angle ψ. is there. FIG. 9A is a schematic diagram when θ ≧ ψ / 2, that is, when θ and ψ satisfy the relationship of the above formula (I). In this case, among the light beams emitted from the light irradiation device, the angle X formed by the light beam 5b (nozzle side) having an irradiation intensity of 3% of the maximum value and the incident surface of the light beam with respect to the polymer optical fiber forming composition is , “90 ° + (θ−ψ / 2)”. Therefore, in the case of θ ≧ ψ / 2 (that is, θ−ψ / 2 ≧ 0), X is 90 ° or an obtuse angle, and the light beam 5b (nozzle side) whose irradiation intensity is 3% of the maximum value is high. The light is incident perpendicular to the composition for forming a molecular optical fiber or inclined toward the ejection direction. In this case, the light beam 5b (nozzle side) having an irradiation intensity of 3% of the maximum value propagates in the polymer optical fiber forming composition toward the ejection direction, while the light that can propagate to the nozzle side is irradiated. Only rays whose intensity is less than 3% of the maximum value. For this reason, the curing reaction of the composition for forming a polymer optical fiber hardly proceeds in the vicinity of the discharge port of the nozzle, and an effect of obtaining a polymer optical fiber with a uniform wire diameter and suppressing yarn breakage can be obtained. On the other hand, if θ and ψ do not satisfy the relationship of the above formula (I), X becomes an acute angle (see FIG. 9B). It may propagate in the nozzle direction and adversely affect the production of polymer optical fibers.

  In addition, the above θ (the minimum value θ of the angle formed between the direction of the maximum intensity light and the surface perpendicular to the discharge direction of the polymer optical fiber forming composition) is, for example, the tip of the light guide of the light irradiation device as described above. The portion can be controlled by an angle inclined to the discharge direction side (for example, downward) of the polymer optical fiber forming composition with respect to a plane (usually a horizontal plane) orthogonal to the discharge direction of the polymer optical fiber forming composition. That is, as the light irradiation device, a mechanism for adjusting the light irradiation angle (specifically, the minimum value θ of the angle formed between the direction of the maximum intensity light and the surface perpendicular to the discharge direction of the precursor). It is preferable to use a light irradiation device provided with (sometimes referred to as “irradiation angle adjustment mechanism”). FIG. 10 is a schematic diagram illustrating an example of a light irradiation apparatus that can be used in step A and includes an irradiation angle adjustment mechanism. In the light irradiation apparatus shown in FIG. 10, the angle of the tip portion of the light guide can be freely adjusted by providing the screw 2f (angle adjusting screw) as the irradiation angle adjusting mechanism.

  In particular, in the process A, as described above, in addition to the embodiment in which the light emitting device is disposed below the discharge port of the multi-tube nozzle (see, for example, FIG. 5), above the discharge port of the multi-tube nozzle. It is also possible to implement by an embodiment in which the emission part of the light irradiation device is arranged and the light is emitted from above the discharge port (this form may be referred to as “epi-illumination method”). As an embodiment of such an epi-illumination method, for example, an embodiment of the epi-illumination method disclosed in JP 2012-159804 A can be applied.

  By the step A in the method for producing a polymer optical fiber of the present invention, a structure in which a polymer optical fiber having at least a core and a clad covering the core is coated with the outermost resin composition is obtained. The structure is a structure in which a part or all of the surface of the polymer optical fiber of the present invention is coated with the outermost layer resin composition. For example, the entire surface of the polymer optical fiber of the present invention is the outermost resin composition. And those in which the outermost resin composition adheres in droplets to the surface of the polymer optical fiber of the present invention (cladding surface).

<Process B>
The method for producing a polymer optical fiber of the present invention includes, after step A, step B of removing the resin composition for outermost layer from the polymer optical fiber coated with the resin composition for outermost layer as an essential step. The polymer optical fiber coated with the above-mentioned outermost layer resin composition may be obtained at the completion of Step A, or after Step A and further through Step C described later. It may be.

  Step B may be performed continuously with another step (for example, step A) or may be performed discontinuously.

  Examples of the method for removing the resin composition for the outermost layer include known or conventional methods capable of removing the resin composition for the outermost layer from the structure to obtain a polymer optical fiber, and are not particularly limited. , Cleaning with a solvent, mechanical removal (polishing, peeling, etc.) and the like. Among these, the removal of the resin composition for the outermost layer is preferably carried out by washing with a solvent in that the operation is simple and a high-quality polymer optical fiber is obtained.

  The solvent used for washing the resin composition for the outermost layer in step B can be appropriately selected according to the type of the resin composition for the outermost layer, and is not particularly limited, but in the section of the resin composition for the outermost layer. The solvent etc. which were illustrated are mentioned. In addition, a solvent can also be used individually by 1 type and can also be used in combination of 2 or more type.

  As a method for washing the polymer optical fiber coated with the outermost layer resin composition in the step B with a solvent, a known or conventional method for washing various products with a solvent can be applied, and is not particularly limited. A method of dissolving the resin composition for the outermost layer by immersing in a solution, a method of dissolving the resin composition for the outermost layer by passing through a solvent, a method of dissolving and dropping the resin composition for the outermost layer by spraying the solvent, a solvent And a method in which these methods using the above are appropriately combined. Moreover, the method of washing | cleaning the resin composition for outermost layers with a solvent may be a continuous method, and may be a batch method. Moreover, the frequency | count of washing | cleaning using the solvent in the process B is not specifically limited. When performing washing | cleaning twice or more, the kind of solvent used in each washing | cleaning process may be the same, and may differ.

  After removing the resin composition for outermost layer by solvent washing in Step B, it is preferable to dry and remove the solvent. The drying can be performed by a known or conventional method.

  A polymer optical fiber (polymer optical fiber having a core and a clad covering the core) in which the resin composition for the outermost layer is removed from the polymer optical fiber coated with the resin composition for the outermost layer by the step B can get. The polymer optical fiber (polymer optical fiber obtained in step B) can also be obtained as the polymer optical fiber of the present invention, and the step obtained after subjecting to step C described later after step B can be obtained. A molecular optical fiber can also be obtained as the polymer optical fiber of the present invention. In addition, the present invention includes a polymer optical fiber obtained in step B and a polymer optical fiber obtained by subjecting the polymer optical fiber obtained after step B to step C described later to further known or conventional processing. It can also be obtained as a polymer optical fiber.

<Process C>
The method for producing a polymer optical fiber of the present invention may further include a step C of performing either one or both of a light irradiation treatment and a heat treatment after the step A. The process C may be performed after the process A, can be performed before the process B, or can be performed after the process B. Further, the process C may be performed both before and after the process B. That is, when the process C is performed before the process B, the process C is a process of performing either one or both of light irradiation treatment and heat treatment on the polymer optical fiber coated with the outermost layer resin composition. On the other hand, when it is carried out after step B, it is a step of performing either one or both of light irradiation treatment and heat treatment on the polymer optical fiber (from which the outermost resin composition has been removed). In particular, in the method for producing a polymer optical fiber of the present invention, it is preferable to include step C because the photocurable composition is used as the curable composition for core formation and the curable composition for clad formation. By passing through the process C, the polymer optical fiber of the present invention exhibits very excellent heat resistance, and there is a tendency that deterioration due to high-temperature heat such as solder reflow treatment or deterioration of optical properties due to shape change is suppressed. is there. Especially, it is preferable that the process C is a process which performs both a light irradiation process and heat processing.

  Step C may be performed continuously after step A or step B, or may be performed discontinuously. When step C is carried out continuously following step A, for example, the polymer optical fiber coated with the outermost layer resin composition obtained in step A is subsequently subjected to light irradiation treatment and / or heating. By performing the process, Step C can be performed. When step C is performed non-continuously with step A or step B, for example, the polymer optical fiber coated with the outermost resin composition obtained in step A or obtained in step B is used. After the polymer optical fiber is wound up and once collected, the light irradiation treatment and / or the heat treatment can be performed in a state where the polymer optical fiber is unwound or wound up.

Although the light irradiated in the light irradiation process of the process C is not specifically limited, For example, an ultraviolet-ray, infrared rays, visible light, an electron beam etc. are mentioned. Among these, ultraviolet rays are preferable because they are easy to handle. The conditions for the light irradiation treatment are not particularly limited. For example, the integrated irradiation amount (the polymer optical fiber coated with the outermost layer resin composition or the total amount of light applied to the polymer optical fiber) is 50 to 6000 mJ / cm ² is preferable, more preferably 60 to 2000 mJ / cm ² , and still more preferably 80 to 1000 mJ / cm ² . When the integrated irradiation amount is less than 50 mJ / cm ² , curing may be insufficient, and a shape change at a high temperature of the polymer optical fiber may easily occur. On the other hand, if the integrated irradiation amount exceeds 6000 mJ / cm ² , the optical properties of the polymer optical fiber may be impaired. Note that the light irradiation treatment can be performed in one stage, or can be performed in two or more stages. The integrated irradiation amount is, for example, a value obtained by converting the irradiation amount of light having a wavelength of 310 to 390 nm into the irradiation amount of light having a wavelength of 365 nm (absolute calibration wavelength) using a light receiver (UVD-S365). It can be measured.

  The light irradiation in the light irradiation treatment can be performed by a known or common method (for example, a method using the above-described light irradiation apparatus), and is not particularly limited. Can be used. In particular, the light irradiation treatment is preferably performed by the same method as the light irradiation in step A.

  Although the heating temperature in the heat processing of the process C is not specifically limited, 40-200 degreeC is preferable, More preferably, it is 50-150 degreeC, More preferably, it is 80-120 degreeC. When the heating temperature is less than 40 ° C., curing becomes insufficient, and the shape change of the polymer optical fiber is likely to occur due to heating. On the other hand, if the heating temperature exceeds 200 ° C., the optical properties of the polymer optical fiber may be impaired. In the heat treatment, the heating temperature may be controlled to be constant, or may be controlled so as to fluctuate stepwise or continuously.

  The heating time in the heat treatment of Step C is not particularly limited, but is preferably 0.01 to 2000 minutes, more preferably 0.1 to 100 minutes, and further preferably 0.2 to 30 minutes. When the heating time is less than 0.01 minutes, curing may be insufficient depending on the heating temperature, and the shape of the polymer optical fiber may be easily changed by heating. On the other hand, when the heating time exceeds 2000 minutes, the productivity of the polymer optical fiber may decrease, or the optical characteristics of the polymer optical fiber may be impaired depending on the heating temperature.

  The heating in the above heat treatment can be performed by a known or conventional method, and is not particularly limited. For example, a heating apparatus (an oven or the like) provided with a heating source such as an oven, hot air, electricity, gas, or infrared rays is used. it can.

  Since the process C can further increase the curing rate (curing degree) of the core and clad of the polymer optical fiber formed in the process A, the process C may be referred to as a “post-curing process”. As described above, the polymer optical fiber obtained through Step C can also be obtained as the polymer optical fiber of the present invention.

  The method for producing a polymer optical fiber of the present invention may include steps (other steps) other than the steps A to C described above. Examples of the other steps include a step of performing known or conventional processing on the polymer optical fiber (for example, a step of providing a coating layer on the outer side of the cladding).

  A polymer optical fiber (polymer optical fiber of the present invention) is manufactured by the above-described method for manufacturing a polymer optical fiber of the present invention. The polymer optical fiber of the present invention is not particularly limited, but can be recovered by appropriately winding up. The winding speed at this time is not particularly limited, but is preferably 10 cm / second to 2 m / second, for example. From the viewpoint of productivity, it is preferable that the winding speed is high. Moreover, the diameter of the polymer optical fiber obtained can be controlled by controlling the winding speed (particularly, the winding speed in step A). Generally, when the winding speed is increased, the wire diameter of the polymer optical fiber forming composition becomes thin, and therefore the wire diameter of the obtained polymer optical fiber tends to be thin. The winding speed can be controlled by using, for example, a winding device (winding machine) for winding and collecting the manufactured polymer optical fiber.

  Furthermore, in the method for producing a polymer optical fiber of the present invention, other devices and devices (for example, a heating unit, a cooling unit, a fiber diameter measuring device, a fiber tension measuring device, etc.) can be used as appropriate. .

  The method for producing a polymer optical fiber of the present invention is a method of ensuring the spinnability by the resin composition for the outermost layer, so that the polymer optical fiber of the present invention having a thin cladding and a large core space factor can be easily obtained. Can be manufactured. On the other hand, a conventional curable composition for forming a core and a curable composition for forming a cladding are simultaneously ejected using a nozzle so that the curable composition for forming a cladding is located in the outermost layer, and then cured. In the method for producing a polymer optical fiber, it was necessary to secure the spinnability with a curable composition for forming a clad, so it was difficult to obtain a polymer optical fiber having a thin clad thickness and a large core space factor. .

  The polymer optical fiber of the present invention may be one in which a suitable coating layer is further provided outside the cladding. Examples of the coating layer include a coating layer made of polyimide, polypropylene, polyethylene, PTFE, polyvinyl chloride, or the like. The thickness of the coating layer is not particularly limited.

  The polymer optical fiber of the present invention is widely used in optical communication applications and decoration applications. In particular, because of its excellent heat resistance and flexibility, for example, communication applications in portable devices, FA devices, OA devices, audio devices, vehicles, LANs, image transmission applications in home and industrial endoscopes, sensor applications, etc. It is particularly useful for light transmission for inspection / measurement lighting, lighting for art works, etc., decoration for billboards, signs, landscape lighting, and the like.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, the unit of the compounding quantity of each component shown in Table 1 is a weight part. Moreover, the compounding quantity about the goods containing a solvent among each component shown in Table 1 was shown with the quantity of goods itself.

Production Examples 1-5
[Production of curable composition]
In accordance with the composition and blending ratio shown in Table 1, a radical polymerizable substance (radical polymerizable compound), a polymerization initiator, and an antioxidant are blended and filtered through a filter having a pore size of 0.2 μm. X1) and (X2) and curable compositions for clad formation (Y1) to (Y3) were produced. The viscosities shown in Table 1 were measured using an E-type viscometer (trade name “VISCONIC”, manufactured by Tokimec Co., Ltd., rotor: 1 ° 34 ′ × R24, rotation speed: 0.5 rpm, measurement temperature: 25 ° C.). Measured.

Production Example 6
[Production of curable composition]
(Production of resin composition (I))
3,4-epoxycyclohexylmethyl (3,4-epoxy) cyclohexanecarboxylate (trade name “Celoxide 2021P”) was added to a 5-neck flask equipped with a monomer dropping line, an initiator dropping line, a thermometer, a reflux pipe, and a stirring blade. (Manufactured by Daicel Corporation) 311.89 g (1.23 mol) and 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane (trade name “OXT-212”, manufactured by Toagosei Co., Ltd.) 155.94 g ( 0.683 mol) of a mixed solution (cationically polymerizable monomer mixed solution) was charged and heated to 80 ± 1 ° C. under a nitrogen stream.
Next, 200.53 g (0 of 3-ethyl-3- (3-acryloyloxy-2,2-dimethylpropyloxymethyl) oxetane (EOXTM-NPAL; compound represented by formula (1c)) was added to the 5-necked flask. .782 mol) and n-butyl acrylate (BA) 500.00 g (3.90 mol) from a monomer dropping line, 30% of the cationic polymerizable monomer mixture and 2, A mixture of 2.15 g (9.38 mmol) of 2′-azobis (isobutyric acid) dimethyl (trade name “V601”, manufactured by Wako Pure Chemical Industries, Ltd.) from the initiator dropping line for 4 hours with a liquid feed pump. It was dripped over. Immediately after the completion of dripping (that is, 4 hours after the start of dripping), 1% of the above cationic polymerizable monomer mixture was added to wash the line, and then held for 2 hours. Then, 2.15 g of “V601” ( 9.38 mmol) and the remainder (5%) of the above cationic polymerizable monomer mixture were added. After maintaining this at 100 ± 1 ° C. for 30 minutes, it was immediately cooled to 40 ° C. or less to obtain a colorless and transparent liquid resin composition (referred to as “resin composition (I)”). The resin composition (I) is a composition (resin composition) containing a copolymer of EOXTM-NPAL and BA, “Celoxide 2021P”, and “OXT-212”.
The polymer (EOXTM-NPAL and BA copolymer) contained in the resin composition (I) had a standard polystyrene equivalent weight average molecular weight of 198,000 and a number average molecular weight of 31,000.

(Manufacture of curable composition for clad formation (Y4))
In accordance with the composition and blending ratio shown in Table 1, a cationic polymerizable substance (resin composition (I) and OXT-DVE) and a polymerization initiator are blended and filtered through a filter having a pore size of 0.2 μm to form a curable composition for clad formation. A product (Y4) was produced. The viscosities shown in Table 1 were measured using an E-type viscometer (trade name “VISCONIC”, manufactured by Tokimec Co., Ltd., rotor: 1 ° 34 ′ × R24, rotation speed: 0.5 rpm, measurement temperature: 25 ° C.). Measured.

Production Example 7
[Manufacture of resin composition for outermost layer]
The resin composition (I) obtained above was used as it is as the outermost resin composition (Z1). The viscosities shown in Table 1 were measured using an E-type viscometer (trade name “VISCONIC”, manufactured by Tokimec Co., Ltd., rotor: 1 ° 34 ′ × R24, rotation speed: 0.5 rpm, measurement temperature: 25 ° C.). Measured.

The symbols shown in Table 1 indicate the following.
A-9550: Trade name “A-9550” (dipentaerythritol polyacrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.)
IBOA: Trade name “IBOA” (isobornyl acrylate, manufactured by Daicel-Cytec)
EB767: Trade name “EBECRYL767” (mixture of linear acrylic oligomer and isobornyl acrylate, manufactured by Daicel Cytec Co., Ltd.)
EB1830: Trade name “EBECRYL1830” (polyester acrylate resin, manufactured by Daicel Cytec Co., Ltd.)
BA: Butyl acrylate Decanediol diacrylate: 1,10-decandiol diacrylate A-BPEF: Trade name “A-BPEF” (9,9-bis [4- (2-acryloyloxyethoxy) phenyl] fluorene, Shin-Nakamura (Chemical Industry Co., Ltd.)
EB114: Product name “EBECRYL114” (phenoxyethyl acrylate, manufactured by Daicel Cytec Co., Ltd.)
A-BPE-4: Trade name “A-BPE-4” (2,2-bis [4- (acryloyloxydiethoxy) phenyl] propane, manufactured by Shin-Nakamura Chemical Co., Ltd.)
OXT-DVE: 3,3-bis (vinyloxymethyl) oxetane Irg184: Trade name “IRGACURE 184” (1-hydroxycyclohexyl phenyl ketone, manufactured by BASF)
CPI-101A: Trade name “CPI-101A” (diphenyl [4- (phenylthio) phenyl] sulfonium hexafluoroantimonate, propylene carbonate, thiodi-p-phenylenebis (diphenylsulfonium) bis (hexafluoroantimonate) mixture, (San Apro Co., Ltd.)
Irg1010: Trade name “IRGANOX 1010” (pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], manufactured by BASF)
X1, X2: Curable composition for core formation Y1-Y4: Curable composition for clad formation Z1: Resin composition for outermost layer

Example 1
The polymer optical fiber was produced using a polymer optical fiber production apparatus shown in FIG. In the polymer optical fiber manufacturing apparatus shown in FIG. 11, 1 is a multi-tube nozzle (triple tube nozzle). The diameters of the inner tube, the first outer tube, and the second outer tube of the multi-tube nozzle 1 are as shown below. As shown in Table 2, the core-forming curable composition (X1) was used as the core-forming curable composition, and the cladding-forming curable composition (Y2) was used as the cladding-forming curable composition. The outermost resin composition (Z1) was used as the outer resin composition.
Moreover, as the light irradiation apparatus used in the process A, the light irradiation apparatus shown in FIG. 6A that can irradiate the polymer optical fiber forming composition 10 from three directions was used. The light irradiation apparatus equidistantly with respect to the polymer optical fiber forming composition 10, the tip portions of three light guides (UV light guides) are equally spaced at the same height (polymer optical fiber forming composition 10 (See FIG. 6 (a)). Further, “SPOTCURE SP9-250DB” (USHIO INC.) Was used as the light source device of the light irradiation device. In FIG. 11, only the tip portions of the two light guides are drawn for convenience.
Further, a light shielding tube 3a is installed at the tip portion 2a of the light guide, and a light shielding plate 3b is installed between the output end of the tip portion 2a of the light guide and the discharge port of the multi-tube nozzle 1.
As shown in FIG. 11, the tip portion 2a of the light guide is disposed below the discharge port of the multi-tube nozzle 1, and the output end (center of the output end) of the tip portion 2a of the light guide from the discharge port of the multi-tube nozzle 1 is arranged. Part) was 20 mm in height (vertical distance). Further, the distance from the output end of the light guide tip 2a (the center of the output end) to the polymer optical fiber forming composition 10 was set to 15 mm.
Furthermore, the tip portion 2a of the light guide was installed to be inclined 11 ° downward with respect to the horizontal plane (that is, θ = 11 °). In addition, the spread angle ψ of light emitted in a state where the front end portion 2a of the light guide is covered with the light shielding cylinder 3a is 22 °.
In addition, the light irradiation process in the process B uses two (two sets) of the same light irradiation apparatus (see FIG. 6A) as the light irradiation apparatus used in the process A, and has two steps as shown in FIG. It carried out by irradiating light. The winding device 8 was used for the subsequent collection of the polymer optical fiber.
[Step A]
First, the core-forming curable composition (X1) 20, the clad-forming curable composition (Y2) 30, and the outermost layer resin composition (Z1) 40 are obtained using the metering pumps 6a, 6b, and 6c. The liquid was injected into the multi-tube nozzle 1 and fed at the following feed rates, respectively, and simultaneously discharged from the tip (discharge port) of the multi-tube nozzle 1 coaxially and downward in the vertical direction in a thread form. The core forming curable composition (X1) 20 is disposed inside the inner tube of the multi-tube nozzle 1, and the cladding forming curable composition (Y2) 30 is disposed between the inner tube and the first outer tube. The outermost layer resin composition (Z1) 40 was fed between the outer tube and the second outer tube. Therefore, the composition 10 for forming a polymer optical fiber discharged from the multi-tube nozzle 1 is coated with the curable composition for core formation with the curable composition for clad formation, and further, the curable composition for clad formation is It is the state (form) coat | covered with the resin composition for outermost layers.
Thereafter, the polymer optical fiber forming composition 10 (X1, Y2, and Z1) was irradiated with ultraviolet rays by a light irradiation device to cure the core forming curable composition 20 and the clad forming curable composition 30. .
(Experimental conditions)
Light irradiation intensity at the outlet of the multi-tube nozzle: 0.15 mW / cm ²
Feed rate of curable composition for core formation (X1): 0.12 mL / min Feed rate of curable composition for core formation (Y2): 0.066 mL / min Feed rate of resin composition for outermost layer (Z1) : 0.55 mL / min Inner diameter (diameter) of inner tube of multi-tube nozzle: 0.3 mm
The outer diameter (diameter) of the inner tube of the multi-tube nozzle: 0.6 mm
Inner diameter (diameter) of the first outer tube of the multi-tube nozzle: 1.0 mm
The outer diameter (diameter) of the first outer tube of the multi-tube nozzle: 1.3 mm
Inner diameter (diameter) of the second outer tube of the multi-tube nozzle: 1.7 mm
UV irradiation intensity with respect to polymer optical fiber forming composition 10 (X1, Y2, and Z1) measured by a light receiver (UVD-S365): 1.8 W / cm ² (total of three sides: 600 mW / cm ² per side)
Winding speed: 250 mm / second (common with process C)

[Step C]
As shown in FIG. 11, after step A, the light irradiation treatment is further continuously performed in two stages, and then wound with a winding device to obtain a polymer optical fiber coated with the outermost layer resin composition. It was. The experimental conditions are as follows.
(Experimental conditions)
Integrated irradiation amount measured by a light receiver (UVD-S365) (converted from a light irradiation amount of wavelength 310 to 390 nm into a light irradiation amount of wavelength 365 nm (absolute calibration wavelength)) (two-step light irradiation) Total): 80 mJ / cm ²
Winding speed: 250 mm / second (common with process A)

[Step B]
By washing the polymer optical fiber coated with the outermost layer resin composition obtained in step C with PGMEA, and then washing with methanol to remove the outermost layer resin composition, and then drying the polymer optical fiber. A polymer optical fiber composed of a core and a clad (polymer optical fiber having a core-clad structure) was obtained.

Examples 2-4
In the same manner as in Example 1 except that the combination of the curable composition for core formation, the curable composition for clad formation, and the resin composition for the outermost layer was changed as shown in Table 2, a polymer optical fiber ( Polymer optical fiber having a core-clad structure) was obtained.

Comparative Example 1
The polymer optical fiber was manufactured using the polymer optical fiber manufacturing apparatus shown in FIG. In the polymer optical fiber manufacturing apparatus shown in FIG. 12, 7 is a double tube nozzle. The diameters of the inner tube and the outer tube of the double tube nozzle 7 are as follows. The polymer optical fiber manufacturing apparatus shown in FIG. 12 has the same configuration as the polymer optical fiber manufacturing apparatus shown in FIG. 11 except that a double tube nozzle is used as the nozzle.
Using the metering pumps 6a and 6b, the core-forming curable composition (X1) 20 and the clad-forming curable composition (Y4) 30 are injected into the double-tube nozzle 7 and fed at the following feed rates, respectively. Then, it was simultaneously discharged from the nozzle tip (discharge port) in the form of a thread downward in the vertical direction. The core-forming curable composition (X1) 20 is sent inside the inner tube of the double tube nozzle 7, and the cladding-forming curable composition (Y4) 30 is sent between the inner tube and the first outer tube. Liquid.
Then, the said curable composition 10 '(X1 and Y4) was irradiated with the ultraviolet-ray with the light irradiation apparatus.
(Experimental conditions)
Light irradiation intensity at the nozzle outlet: 0.15 mW / cm ²
Feed rate of curable composition for core formation (X1): 0.05 mL / min Feed rate of curable composition for core formation (Y4): 0.25 mL / min Inner diameter (diameter) of inner tube of double tube nozzle : 0.3mm
Outer diameter (diameter) of inner pipe of double pipe nozzle: 0.6mm
Inner diameter (diameter) of outer tube of double tube nozzle: 1.0 mm
UV irradiation intensity with respect to curable composition 10 ′ (X1 and Y4) measured with a light receiver (UVD-S365): 1.8 W / cm ² (total of three sides: 600 mW / cm ² per side)
Winding speed: 400mm / sec

As shown in FIG. 12, after the above process, the light irradiation treatment was further continuously performed in two stages, and then wound up by a winding device 8 to obtain a polymer optical fiber. The experimental conditions are as follows.
(Experimental conditions)
Integrated irradiation amount measured by a light receiver (UVD-S365) (converted from a light irradiation amount of wavelength 310 to 390 nm into a light irradiation amount of wavelength 365 nm (absolute calibration wavelength)) (two-step light irradiation) Total): 80 mJ / cm ²
Winding speed: 400 mm / sec (common to the above process)

[Evaluation]
(Evaluation of fiberization)
The case where a polymer optical fiber (fibrous cured product) of 100 m or more could be manufactured was evaluated as ○ (can be fiberized), and the case where it could not be manufactured was evaluated as x (cannot be fiberized). It is shown in the column.

(Evaluation of heat resistance)
The polymer optical fibers obtained in Examples 1 to 4 were heated at 260 ° C. for 10 minutes, and the optical loss at 850 nm before and after heating was measured. The case where the amount of change from light loss before heating is 0.1 dB · cm ⁻¹ or less is evaluated as ○ (with heat resistance), and the case where it exceeds 0.1 dB · cm ⁻¹ is evaluated as × (without heat resistance). These are shown in the column of “Heat resistance” in Table 2.
The light loss was measured by the following procedure.
Examples 1 to 4 and comparison were performed using light from a light source having a wavelength of 850 nm (MLXA-D12-850-50 (CN4) manufactured by Kikko Giken Co., Ltd.) using a lens (OBL-20 manufactured by Sigma Koki Co., Ltd.). The polymer optical fiber obtained in Example 1 was introduced. The light emitted from the polymer optical fiber was received by a photodiode (OPHIR PD300), connected to a power meter (OPHIR VEGA), and light loss was measured.

(Evaluation of flexibility)
The presence or absence of cracks (cracks) when the polymer optical fibers obtained in Examples 1 to 4 and Comparative Example 1 were wound around a rod having a radius of 1 mm was visually observed. As a result, the case where no crack (crack) occurred was evaluated as flexible, and the case where a crack (crack) occurred was evaluated as not flexible.

(Clad thickness)
The diameter of the polymer optical fiber obtained in Examples 1 to 4 and Comparative Example 1 and the diameter of the core of the polymer optical fiber are shown in the column of “core diameter (μm) / fiber diameter (μm)” in Table 2, respectively. It was. From these diameters, the thickness of the clad in the polymer optical fiber (cladding thickness) was calculated according to the following formula and shown in the column of “Clad Thickness (μm)” in Table 2. In addition, the said diameter was measured from the photograph of the cross section using a digital microscope.
[Clad thickness (μm)] = ([Polymer optical fiber diameter (μm)] − [Core diameter (μm)]) / 2

(Core space factor)
From the cross-sectional area of the polymer optical fiber obtained in Examples 1 to 4 and Comparative Example 1 and the cross-sectional area of the core of the polymer optical fiber, the space factor (%) of the core in the polymer optical fiber is calculated by the following formula. These are shown in the column of “core space factor (%)” in Table 2. The cross-sectional area was calculated using the diameter measured above.
[Core space factor (%)] = ([Cross sectional area of core (μm ² )] / [Cross sectional area of polymer optical fiber (μm ² )]) × 100

DESCRIPTION OF SYMBOLS 1 Multiple tube nozzle 1a Inner tube 1b 1st outer tube 1c 2nd outer tube 1d Discharge port 1e-1g Inlet 1h Adjustment screw 2 Light irradiation device 2a Light guide tip part 2b Light guide 2c Light source device 2d Base (support) )
2e Foundation (support)
2f Irradiation angle adjusting mechanism 3a Light-shielding cylinder 3b Light-shielding plate 3c Hole 4 for allowing the polymer optical fiber forming composition to pass through 4a Position through which the polymer optical fiber-forming composition passes 5a Maximum intensity light 5b % Of light beam 5c divergence angle (ψ)
6a to 6c Metering pump 7 Double tube nozzle 8 Winding device 10 Polymer optical fiber forming composition 10 'Core forming curable composition and clad forming curable composition 20 Core forming curable composition 30 Cladding Curable composition 40 for outermost layer resin composition 100 polymer optical fiber 200 core 300 clad 400 polymer optical fiber coated with outermost layer resin composition

Claims (6)

An optical fiber having a core made of a polymer material and a clad made of a polymer material covering the core,
Each of the polymer materials is a cured product of a photocurable composition,
A polymer optical fiber, wherein the clad has a thickness of 1 to 20 μm.   The polymer optical fiber according to claim 1, wherein a space factor of the core is 30% or more.   Using a nozzle, a curable composition for forming a core for forming a polymer material constituting a core and a curable composition for forming a clad for forming a polymer material constituting a clad are used to form a polymer optical fiber. In the form corresponding to the form of the core and the clad, the core-forming curable composition and the clad-forming curable composition are cured by light irradiation after being simultaneously ejected coaxially into a fiber shape. The polymer optical fiber according to claim 1 or 2.   The polymer optical fiber according to claim 3, wherein both the core-forming curable composition and the clad-forming curable composition are photo-radical polymerizable compositions.   The radical photopolymerizable composition is at least one selected from the group consisting of (meth) acryloyl group, (meth) acryloyloxy group, (meth) acryloylamino group, vinylaryl group, vinyl ether group, and vinyloxycarbonyl group. The polymer optical fiber according to claim 4, comprising a radical polymerizable compound having one or more radical polymerizable groups in the molecule.   The polymer optical fiber according to any one of claims 3 to 5, wherein one or both of the curable composition for forming a core and the curable composition for forming a clad contain an antioxidant.

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