JP2018052762A - Optical fiber coating material, coated optical fiber, and method for producing coated optical fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber coating material that can improve an interfacial adhesion between a glass optical fiber and a coating layer and allows easy coating, and a coated optical fiber containing the coating material and a method of producing the same.SOLUTION: A coated optical fiber 10 has a glass optical fiber 11, and a coating layer 14 that coats the periphery of the glass optical fiber. The coating material of the coating layer contains an ultraviolet-curable resin, a silane coupling agent, and a photoacid generator that generates acid by light irradiation. The acid generated from the photoacid generator promotes the hydrolysis of the silane coupling agent and dehydration condensation thereof.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a coating material for an optical fiber, a coated optical fiber including the coating material, and a method for manufacturing the coated optical fiber.

  An optical fiber is generally manufactured by coating an outer periphery of a glass optical fiber drawn from a preform (also referred to as an optical fiber preform) with an ultraviolet curable resin and curing it by ultraviolet irradiation. The coating layer of the optical fiber prevents the glass optical fiber that is the waveguide from being broken, prevents dust and other dust and moisture from entering, and the glass optical fiber is micro-deformed by the force applied from the outside of the optical fiber. The object is to prevent light transmission loss caused by bending. In order to achieve these objects, a high interfacial adhesion is required between the glass optical fiber and the coating layer.

  Optical fibers are used in various environments including outdoors. Therefore, it is desirable that the interfacial adhesion between the glass optical fiber and the coating layer be maintained even in a high humidity atmosphere. However, an ultraviolet curable resin suitable for a coating layer of an optical fiber does not adhere strongly to the glass surface as it is. Furthermore, when moisture enters the coating layer, the adhesive force between the glass optical fiber and the coating layer is significantly reduced.

  In order to improve the interfacial adhesion between the glass optical fiber and the coating layer, for example, the techniques described in Patent Documents 1 and 2 add a silane coupling agent to a coating material containing an ultraviolet curable resin. The silane coupling agent reacts or interacts with the surface of the glass optical fiber by hydrolysis reaction and dehydration condensation reaction, and improves the interfacial adhesion.

JP 59-92947 A JP-T-2005-504698 JP 2013-91575 A

  It is known that the reaction rate of the hydrolysis reaction and dehydration condensation reaction of a silane coupling agent generally increases in an acid or base environment. Therefore, in order to promote the reaction of the silane coupling agent and improve the interfacial adhesion, a method of making the resin composition used as the coating material acidic or basic can be considered.

  However, when the resin composition is acidified, the viscosity becomes very high and cannot be uniformly applied to the glass optical fiber. Moreover, since the glass optical fiber is damaged when the resin composition is made basic, the strength of the glass optical fiber is lowered. Furthermore, when the resin composition is made acidic or basic, the reaction of the silane coupling agent proceeds spontaneously during storage, and the resin composition becomes cloudy. That is, in the method of making the resin composition acidic or basic, since it is difficult to handle the resin composition, there is a problem that the production of the coated optical fiber becomes more difficult than before.

  The technique described in Patent Document 3 promotes the reaction of the silane coupling agent by applying an acid-imparting substance to the surface of the glass optical fiber, rather than making the resin composition itself acidic. However, in this method, the equipment tends to deteriorate due to the acid-imparting substance, and it is difficult to control the amount of the acid-imparting substance applied, so that the production of the coated optical fiber becomes more difficult than before.

  The present invention has been made in view of the above-described problems, and can improve the interfacial adhesion between the glass optical fiber and the coating layer and can be easily coated, and the coating material for the optical fiber. It is an object of the present invention to provide a coated optical fiber containing a material and a method for manufacturing the same.

  A first aspect of the present invention is an optical fiber coating material, which includes an ultraviolet curable resin, a silane coupling agent, and a photoacid generator that generates an acid upon irradiation with light.

  According to a second aspect of the present invention, there is provided a method for producing a coated optical fiber, the step of drawing a glass optical fiber, and an acid applied to the glass optical fiber by irradiation with an ultraviolet curable resin, a silane coupling agent and light. A step of coating a coating material containing a photoacid generator to be generated; and irradiating the glass optical fiber coated with the coating material with ultraviolet rays, thereby curing the ultraviolet curable resin and applying the photoacid generator to the photoacid generator. Generating the acid.

  According to the present invention, since the photoacid generator that generates an acid upon irradiation with light is added to the coating material of the optical fiber, the reaction of the silane coupling agent is simultaneously accelerated by the light for curing the ultraviolet curable resin. be able to. In the state where light is not irradiated, since the acid is hardly generated from the photoacid generator, the coating material can be easily handled. In addition, since the light for curing the ultraviolet curable resin is also used for the generation of acid from the photoacid generator, there is no need to change the conventional method for manufacturing a coated optical fiber.

It is sectional drawing of the covering optical fiber which concerns on 1st Embodiment. It is a schematic diagram of the manufacturing apparatus used for the manufacturing method of the coating optical fiber which concerns on 1st Embodiment. It is a figure which shows the flowchart of the manufacturing method of the coating optical fiber which concerns on 1st Embodiment. It is a schematic diagram of the manufacturing apparatus used for the manufacturing method of the coated optical fiber which concerns on 2nd Embodiment. It is a figure which shows the flowchart of the manufacturing method of the coating optical fiber which concerns on 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments. In the drawings described below, components having the same function are denoted by the same reference numerals, and repeated description thereof may be omitted.

(First embodiment)
FIG. 1 is a cross-sectional view of a coated optical fiber 10 according to this embodiment. As shown in FIG. 1, the coated optical fiber 10 includes a glass optical fiber 11 and a primary layer 12 (primary coating layer) and a secondary layer 13 (secondary coating layer) coated on the outer periphery of the glass optical fiber 11. And two coating layers 14. The primary layer is a soft layer having a Young's modulus of 0.2 MPa to 3.0 MPa, and the secondary layer is a hard layer having a Young's modulus of 500 MPa to 2500 MPa. The primary layer 12 and the secondary layer 13 are each formed of a layer formed by irradiating and curing an optical fiber coating material containing an ultraviolet curable resin, and has a function of protecting the glass optical fiber 11. Yes.

  The coated optical fiber 10 is not limited to the configuration shown in FIG. For example, the coating layer 14 may be a single layer having a Young's modulus of 0.2 MPa to 2000 MPa. The covering layer 14 may include three or more layers. The coated optical fiber 10 may take the form of an optical fiber core wire that further includes a colored layer coated on the outer periphery of the coating layer 14. The coated optical fiber 10 may take the form of an optical fiber ribbon that further includes a collective coating layer that bundles a plurality of coated optical fibers 10.

  The diameter of the glass optical fiber 11 is usually 80 μm or more and 150 μm or less, and generally 124 μm or more and 126 μm or less. The thickness of the primary layer 12 is usually 5 μm or more and 50 μm or less, and the thickness of the secondary layer 13 is usually 5 μm or more and 50 μm or less. The diameter of the coated optical fiber 10 (that is, the outer diameter of the secondary layer 13) is usually 200 μm or more and 255 μm or less.

  The coating material of the coating layer 14 includes an ultraviolet curable resin. The ultraviolet curable resin is, for example, an ultraviolet curable resin having at least two ethylenically unsaturated groups that are polymerized and cured by ultraviolet rays, and is preferably an oligomer. Here, the oligomer is a polymer having a degree of polymerization of 2 or more and 100 or less.

  Further, the coating material of the coating layer 14 includes a silane coupling agent that interacts with the surface of the glass optical fiber 11 by hydrolysis and dehydration condensation, and Lewis acid, Bronsted acid, and the like by irradiation with active energy rays emitted from a light source. Includes a photoacid generator that generates acid. The acid generated from the photoacid generator promotes hydrolysis and dehydration condensation of the silane coupling agent, and improves the adhesion between the resin contained in the coating layer 14 and the glass optical fiber 11.

[Photoacid generator]
The photoacid generator absorbs irradiated light, then decomposes, and generates hydrogen by extracting hydrogen from the solvent or the acid generator itself. The light absorbed by the photoacid generator varies depending on the type of the photoacid generator, but is, for example, ultraviolet light having a wavelength range of about 10 nm to 405 nm. It is desirable that at least a part of the wavelength region of light that cures the ultraviolet curable resin contained in the coating material of the coating layer 14 overlaps the wavelength region of light that generates acid in the photoacid generator. Thereby, the curing of the ultraviolet curable resin and the generation of the acid by the photoacid generator can be performed simultaneously by the light from one kind of light source.

Photoacid generators can be broadly classified into onium salt photoacid generators and nonionic photoacid generators. In this embodiment, at least one of an onium salt photoacid generator and a nonionic photoacid generator is used, but other types of photoacid generators may be used. The onium salt photoacid generator that can be used for the coating material of the coating layer 14 is not particularly limited, and examples thereof include organic sulfonium salt compounds, organic oxonium salt compounds, organic ammonium salt compounds, organic phosphonium salt compounds, and organic iodonium salt compounds. Examples thereof include those having a counter anion such as a hexafluoroantimonate anion, a tetrafluoroborate anion, a hexafluorophosphate anion, a hexachloroantimonate anion, a trifluoromethanesulfonate ion, or a fluorosulfonate ion. The specific chemical formula of the counter anion is, for example, an anion represented by B (C ₆ F ₅ ) ₄ ⁻ , SbF ₆ ⁻ , SbF ₄ ⁻ , AsF ₆ ⁻ , PF ₆ ⁻ , BF ₄ ⁻ and CF ₃ SO ₃ ⁻ It is. These may be used alone or in combination of two or more.

  Examples of commercially available onium salt photoacid generators include IRGACURE (registered trademark, hereinafter omitted) 250, IRGACURE 270 (above, trade name, manufactured by BASF), WPI-113, WPI-116, WPI-169, WPI- 170, WPI-124, WPAG-638, WPAG-469, WPAG-370, WPAG-367, WPAG-336 (above, Wako Pure Chemical Industries, Ltd., trade name), B2380, B2381, C1390, D2238, D2248, D2253, I0591, T1608, T1609, T2041, T2042 (above, trade name, manufactured by Tokyo Chemical Industry Co., Ltd.), AT-6992, At-6976 (above, trade name, made by ACETO), CPI-100, CPI-100P , CPI-101A, CPI-200K, CP -210S (above, San Apro Co., Ltd., trade name), SP-056, SP-066, SP-130, SP-140, SP-150, SP-170, SP-171, SP-172 (above, ADEKA shares) Company-made, trade name), CD-1010, CD-1011, CD-1012 (above, trade name, manufactured by Sartomer), PI 2074 (trade name, made by Rhodia Japan) and the like.

  The nonionic photoacid generator that can be used for the coating material of the coating layer 14 is not particularly limited. For example, phenacylsulfone photoacid generator, o-nitrobenzyl ester photoacid generator, iminosulfonate photo Examples thereof include acid generators and N-hydroxyimide sulfonic acid ester photoacid generators. These may be used alone or in combination of two or more. Specific examples of the nonionic photoacid generator include sulfonyldiazomethane, oxime sulfonate, imide sulfonate, 2-nitrobenzyl sulfonate, disulfone, pyrogallol sulfonate, p-nitrobenzyl-9,10-dimethoxyanthracene-2- Sulfonate, N-sulfonyl-phenylsulfonamide, trifluoromethanesulfonic acid-1,8-naphthalimide, nonafluorobutanesulfonic acid-1,8-naphthalimide, perfluorooctanesulfonic acid-1, 8-naphthalimide, pentafluoro Benzenesulfonic acid-1,8-naphthalimide, nonafluorobutanesulfonic acid-1,3,6-trioxo-3,6-dihydro-1H-11-thia-azacyclopentanthracen-2-yl ester, nona Luobutanesulfonic acid-8-isopropyl-1,3,6-trioxo-3,6-dihydro-1H-11-thia-2-azacyclopentanthracen-2-yl ester, 1,2-naphthoquinone-2- Diazide-5-sulfonic acid chloride, 1,2-naphthoquinone-2-diazide-4-sulfonic acid chloride, 1,2-benzoquinone-2-diazido-4-sulfonic acid chloride, 1,2-naphthoquinone-2-diazide- Sodium 5-sulfonate, sodium 1,2-naphthoquinone-2-diazide-4-sulfonate, sodium 1,2-benzoquinone-2-diazide-4-sulfonate, 1,2-naphthoquinone-2-diazide-5 Potassium sulfonate, 1,2-naphthoquinone-2-diazide-4-sulfonate, 1,2-benzoquinone-2 Potassium diazide-4-sulfonic acid, 1,2-naphthoquinone-2-diazide-5-sulfonic acid methyl, 1,2-benzoquinone-2-diazide-4-sulfonic acid methyl and the like.

  As a commercial item of a nonionic photo-acid generator, WPAG-145, WPAG-149, WPAG-170, WPAG-199 (above, the Wako Pure Chemical Industries Ltd. make, brand name), D2963, F0362, M1209, M1245 (above, Tokyo Chemical Industry Co., Ltd., trade name), SP-082, SP-103, SP-601, SP-606 (above, ADEKA Corporation, trade name), SIN-11 (Sanpo Chemical Co., Ltd.) Laboratories, trade name), NT-1TF (trade name, manufactured by Sun Apro Co., Ltd.) and the like.

  The addition amount of the photoacid generator is 0.01 wt% or more, preferably 0.1 wt% or more with respect to the coating material of the coating layer 14. When the amount of the photoacid generator is less than this, the amount of acid generated from the photoacid generator is small, so the progress rate of the hydrolysis reaction and dehydration condensation reaction of the silane coupling agent is reduced, and the coating layer 14 and It takes time to develop adhesiveness with the glass optical fiber 11. Note that “wt%” indicates a weight percent concentration (hereinafter the same).

  Further, it is desirable that the amount of the photoacid generator added is not more than the amount of the photopolymerization initiator contained in the coating material of the coating layer 14. When the photoacid generator is added more than the photopolymerization initiator, the curability of the coating layer 14 is reduced because the reaction of the photopolymerization initiator that similarly absorbs ultraviolet rays and generates radical species is inhibited. The elastic modulus may be reduced. Specifically, the addition amount of the photoacid generator is 10 wt% or less, preferably 5 wt% or less with respect to the coating material of the coating layer 14.

[Silane coupling agent]
As the silane coupling agent, any known silane coupling agent can be used as long as it does not interfere with the effects of the present invention. The addition amount of the silane coupling agent is appropriately determined by experiments or the like. Although it does not specifically limit as a specific compound of a silane coupling agent, For example, tetramethyl silicate, tetraethyl silicate, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyl Trimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxy Silane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane 3-acryloxypropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, tris- (trimethoxysilylpropyl) isocyanate Examples include nurate, 3-ureidopropyltrialkoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-isocyanatopropyltriethoxysilane.

  The addition amount of the silane coupling agent is preferably 0.1 wt% or more and 10 wt% or less, more preferably 0.5 wt% or more and 5.0 wt% or less with respect to the coating layer 14. Within the above range, the adhesion between the glass optical fiber and the coating layer 14 is sufficient, and the storage stability of the coating material is excellent.

  Furthermore, the coating material of the coating layer 14 may contain a dilution monomer, a photosensitizer, a photopolymerization initiator, a chain transfer agent, and various additives. Monofunctional (meth) acrylate or polyfunctional (meth) acrylate is used as the dilution monomer. The dilution monomer is a monomer for diluting the ultraviolet curable resin.

[Photopolymerization initiator]
The photopolymerization initiator absorbs light in a wavelength region emitted from an ultraviolet irradiation device and generates radicals to start polymerization in the ultraviolet curable resin. The addition amount of the photopolymerization initiator is appropriately determined by experiments or the like. Although it does not specifically limit as a photoinitiator, For example, an acyl phosphine oxide type photoinitiator, an acetophenone type photoinitiator, an o-acyl oxime type photoinitiator, etc. can be used.

[Photosensitizer]
The photosensitizer is added to the coating material of the coating layer 14 for the purpose of improving the photosensitivity of the photoacid generator. The photosensitizer improves the photosensitivity of the photoacid generator by absorbing light in a wavelength region that cannot be absorbed by the photoacid generator. Therefore, the absorption wavelength region of the photosensitizer is different from the absorption wavelength region of the photoacid generator, and it is preferable that the overlap thereof is as small as possible.

  The addition amount of the photosensitizer is preferably 0.1 wt% or more and 10 wt% or less, and more preferably 0.5 wt% or more and 10 wt% or less with respect to the coating material of the coating layer 14. When the content of the photosensitizer is 0.1 wt% or more, desired sensitivity is easily obtained, and when it is 10 wt% or less, the transparency of the coating is easily ensured.

  Although it does not specifically limit as a photosensitizer which can be used for the coating material of the coating layer 14, For example, an anthracene derivative, a benzophenone derivative, a thioxanthone derivative, an anthraquinone derivative, a benzoin derivative etc. are mentioned. More specifically, as a photosensitizer, 9,10-dialkoxyanthracene, 2-alkylthioxanthone, 2,4-dialkylthioxanthone, 2-alkylanthraquinone, 2,4-dialkylanthraquinone, p, p′-aminobenzophenone, Examples include 2-hydroxy-4-alkoxybenzophenone and benzoin ether.

  Specific compounds of the photosensitizer are not particularly limited. For example, anthrone, anthracene, 9,10-diphenylanthracene, 9-ethoxyanthracene, pyrene, perylene, coronene, phenanthrene, benzophenone, benzyl, benzoin, 2- Methyl benzoylbenzoate, butyl 2-benzoylbenzoate, benzoin ethyl ether, benzoin-i-butyl ether, 9-fluorenone, acetophenone, p, p'-tetramethyldiaminobenzophenone, p, p'-tetraethylaminobenzophenone, 2-chloro Thioxanthone, 2-isopropylthioxanthone, 2,4-diethylthioxanthone, phenothiazine, acridine orange, benzoflavin, cetoflavin-T, 2-nitrofluorene, 5-nitroacetate Futen, benzoquinone, 2-chloro-4-nitroaniline, N-acetyl-p-nitroaniline, p-nitroaniline, N-acetyl-4-nitro-1-naphthylamine, picramid, anthraquinone, 2-ethylanthraquinone, 2- tert-butylanthraquinone, 1,2-benzanthraquinone, 3-methyl-1,3-diaza-1,9-benzanthrone, dibenzalacetone, 1,2-naphthoquinone, 3,3′-carbonyl-bis (5 , 7-dimethoxycarbonylcoumarin), 9,10-dibutoxyanthracene, 9,10-dipropoxyanthracene and the like. These may be used alone or in combination of two or more.

[Thermal acid generator]
Furthermore, the coating material of the coating layer 14 may contain a thermal acid generator. The thermal acid generator is decomposed by heat to generate an acid. The addition of an excessive photoacid generator may also inhibit the reaction of the photopolymerization initiator that absorbs ultraviolet rays and generates radical species. Therefore, the effect of the photoacid generator can be compensated by suppressing the addition amount of the photoacid generator and adding the thermal acid generator together.

  When a thermal acid generator is added to the coating material, heating is performed at the acid generation temperature (decomposition temperature) of the thermal acid generator during or after the production of the coated optical fiber 10. The thermal acid generator can generate an acid without performing an additional step by heat from a light source at the time of curing the ultraviolet curable resin or reaction heat of the resin itself. Moreover, you may set an additional heating process separately like 2nd Embodiment mentioned later. In that case, the heating step is to install a device for heating the coated optical fiber 10 after curing of the resin after the ultraviolet irradiation device, or to put the coated optical fiber 10 after manufacture into a thermostatic bath and perform heat aging. . By heating, the acid generated by the thermal acid generator further promotes the reaction of the silane coupling agent, and the glass adhesion can be improved.

  The acid generation temperature (decomposition temperature) of the thermal acid generator is preferably 60 ° C. or higher and 200 ° C. or lower, and particularly preferably 80 ° C. or higher and 150 ° C. or lower in order to reduce the influence on the coated optical fiber 10. The addition amount of the thermal acid generator is 0.01 wt% or more and 10 wt% or less, preferably 0.1 wt% or more and 5 wt% or less with respect to the coating material of the coating layer 14. If the amount is less than this range, the amount of acid generated is small, so the effect of promoting the hydrolysis reaction and dehydration condensation reaction of the silane coupling agent is low, and it takes time to develop the adhesion between the coating layer 14 and the glass optical fiber 11. Cost. If it exceeds this range, the storage stability of the coating material may be lowered.

The thermal acid generator that can be used for the coating material of the coating layer 14 is not particularly limited as long as it generates an acid by thermal decomposition. For example, as the thermal acid generator, an organic onium salt compound in which a cation component and an anion component are paired is used. Examples of the cation component of the thermal acid generator include various onium salt compounds such as organic sulfonium salt compounds, organic oxonium salt compounds, organic ammonium salt compounds, organic phosphonium salt compounds, and organic iodonium salt compounds. Examples of the anionic component of the thermal acid generator include B (C ₆ F ₅ ) ₄ ⁻ , SbF ₆ ⁻ , SbF ₄ ⁻ , AsF ₆ ⁻ , PF ₆ ⁻ , BF ₄ ⁻ , CF ₃ SO ₃ ^{− and the} like. Can be mentioned. Also, organometallic complexes such as aluminum chelate complexes, iron-allene complexes, titanocene complexes, arylsilanol-aluminum complexes, oxime sulfonate acid generators, bisalkyl or bisarylsulfonyldiazomethanes, poly (bissulfonyl) diazomethanes, etc. Diazomethane acid generators, nitrobenzyl sulfonate acid generators, imino sulfonate acid generators, disulfone acid generators and the like also function as thermal acid generators. These may be used alone or in combination of two or more.

  FIG. 2 is a schematic diagram of a manufacturing apparatus 20 used in the method for manufacturing the coated optical fiber 10 according to the present embodiment. The optical fiber preform 21 is made of, for example, quartz glass and is manufactured by a known method such as a VAD method, an OVD method, or an MCVD method. The end portion of the optical fiber preform 21 is heated and melted by a heater 22 which is a heating device disposed around the optical fiber preform 21, and drawn to draw a glass optical fiber 23 (that is, the glass optical fiber of FIG. 1). 11) is pulled out.

  Below the heater 22, a resin coating device 24 (a die) for applying an ultraviolet curable resin to the outer periphery of the glass optical fiber 23 is provided. The resin coating device 24 holds a coating material for the primary layer 12 (also referred to as a primary layer material) and a coating material for the secondary layer 13 (also referred to as a secondary layer material) separately. Here, at least the primary layer material is a coating material containing the above-mentioned silane coupling agent and photoacid generator. The secondary layer material is not limited to the above-described configuration, and may not include, for example, a silane coupling agent and a photoacid generator. A primary layer material and a secondary layer material are collectively applied to the glass optical fiber 23 drawn from the optical fiber preform 21 by a resin coating device 24.

  Below the resin coating device 24, an ultraviolet irradiation device 26 for irradiating the glass optical fiber 25 coated with the primary layer material and the secondary layer material with ultraviolet rays is provided. The ultraviolet irradiation device 26 includes an arbitrary ultraviolet light source such as a semiconductor light emitting element or a mercury lamp. The glass optical fiber 25 coated with the ultraviolet curable resin by the resin coating device 24 enters the ultraviolet irradiation device 26 and is irradiated with ultraviolet rays. As a result, the two layers of ultraviolet curable resin coated on the outer periphery of the glass optical fiber 25 are cured, and the two layers of ultraviolet curable resin become the primary layer 12 and the secondary layer 13.

  The glass optical fiber (that is, the coated optical fiber 10) having the primary layer 12 and the secondary layer 13 formed on the outer periphery is guided by the guide roller 27 and wound by the winding device 28.

  Although the manufacturing method of the coated optical fiber 10 according to the present embodiment uses a wet-on-wet method in which the primary layer 12 and the secondary layer 13 are applied and cured with a single die, the primary layer 12 and the secondary layer 13 are used. Wet-On-Dry method may be used in which is applied with a separate die and cured.

  FIG. 3 is a diagram illustrating a flowchart of the method for manufacturing the coated optical fiber 10 according to the present embodiment. First, the user installs the optical fiber preform 21 in the manufacturing apparatus 20 (step S11). Next, the heater 22 heats the optical fiber preform 21 and starts drawing the glass optical fiber 23 (step S12).

  The resin coating device 24 coats the drawn glass optical fiber 23 with the primary layer material (step S13), and then coats the secondary layer material (step S14). The ultraviolet irradiation device 26 irradiates the glass optical fiber 25 coated with the primary layer material and the secondary layer material with ultraviolet rays (step S15). By irradiation with ultraviolet rays, the primary layer material and the secondary layer material are cured, and the coated optical fiber 10 including the primary layer 12 and the secondary layer 13 is formed. At the same time, an acid is generated from the photoacid generator contained in the coating material by irradiation with ultraviolet rays, and the reaction of the silane coupling agent is promoted.

  The coating material used for the coating layer 14 (particularly the primary layer 12) of the coated optical fiber 10 according to this embodiment includes a photoacid generator. Since the photoacid generator generates an acid only upon irradiation with ultraviolet rays, the acid is generated simultaneously with the ultraviolet curing of the coating material. The progress of hydrolysis reaction and dehydration condensation reaction of the silane coupling agent is promoted by the generated acid, and high adhesion between the glass optical fiber 11 and the coating layer 14 can be obtained immediately after UV curing.

  In conventional optical fiber cores, it has been reported that optical loss increases due to water immersion. When the optical fiber core is immersed for a long period of time, the adhesion decreases, for example, at the glass optical fiber / primary layer interface, causing partial delamination, which causes water to accumulate in the formed space and further exfoliation. To do. When the separation occurs at the glass optical fiber / primary layer interface and water accumulates, a lateral pressure is applied to the glass optical fiber, resulting in an increase in light loss due to microbending. In the optical fiber core using the coated optical fiber 10 according to the present embodiment, the adhesion of the glass optical fiber / primary layer interface is improved, so that it is possible to suppress an increase in optical loss due to water immersion of the optical fiber core. it can.

  In addition, since the coated optical fiber 10 according to the present embodiment has improved adhesion at the glass optical fiber / primary layer interface, the durability of the breaking strength of the glass optical fiber 11 (expressed by dynamic fatigue characteristics) is long. It can be stably maintained over a period.

  In the configuration in which the coating material is previously made acidic or basic in order to promote the reaction of the silane coupling agent, there is a problem that the reaction of the silane coupling agent naturally proceeds during storage. On the other hand, the coating material according to this embodiment has good storage stability because it hardly generates acid from the photoacid generator when stored in a dark place.

  In the configuration in which the acid-imparting substance is applied to the surface of the glass optical fiber as in the technique described in Patent Document 3, an additional application process is necessarily required during the production of the coated optical fiber. On the other hand, in the manufacturing method of the coated optical fiber 10 according to the present embodiment, the photoacid generator is also decomposed at the wavelength of the light source conventionally used for decomposing the photopolymerization initiator, thereby generating an acid. There is no need to change the manufacturing process.

(Second Embodiment)
In the present embodiment, the interface adhesive force between the glass optical fiber 11 and the coating layer 14 is further improved by heating the coating material of the coating layer 14. Except for the configuration and processes related to the heating of the coating material of the coating layer 14, it is the same as in the first embodiment.

  FIG. 4 is a schematic diagram of a manufacturing apparatus 20 used in the method for manufacturing the coated optical fiber 10 according to the present embodiment. In the manufacturing apparatus 20 according to the present embodiment, in addition to the configuration of the first embodiment, a heating apparatus 29 that heats the coated optical fiber 10 (that is, the coating material of the coating layer 14) is provided below the ultraviolet irradiation apparatus 26. . The heating device 29 includes an arbitrary heat source such as a tape heater, a ribbon heater, a rubber heater, an oven heater, a ceramic heater, an infrared irradiation unit, an ultraviolet irradiation unit, a heating wire heater, a carbon heater, or a halogen heater. The heating temperature by the heating device 29 is preferably 60 ° C. or higher and 200 ° C. or lower, and particularly preferably 80 ° C. or higher and 150 ° C. or lower in order to suppress damage to the coated optical fiber 10.

  FIG. 5 is a diagram illustrating a flowchart of the method for manufacturing the coated optical fiber 10 according to the present embodiment. Steps S11 to S15 are the same as in the first embodiment. After irradiating with ultraviolet rays in step S15, the heating device 29 heats the coated optical fiber 10 (that is, the coating material of the coating layer 14) at a predetermined temperature (step S16).

  In the coating material, the hydrolysis reaction and dehydration condensation reaction of the silane coupling agent by the acid generated from the photoacid generator are accelerated by heat. In this embodiment, since the action of the photoacid generator described in the first embodiment is promoted by heating, the interfacial adhesion between the glass optical fiber 11 and the coating layer 14 can be further improved.

  In addition to the photoacid generator, a thermal acid generator may be added to the coating material. As a result, since acid is generated from the thermal acid generator in the heating step, the hydrolysis reaction and dehydration condensation reaction of the silane coupling agent can be further promoted than when only the photoacid generator is used.

  In this embodiment, the heating process is performed after the ultraviolet irradiation process, but the present invention is not limited to this as long as the coating material of the coating layer 14 can be heated. For example, the ultraviolet irradiation device 26 and the heating device 29 may be integrated as one device, and the heating process may be performed simultaneously with the ultraviolet irradiation process. Specifically, an ultraviolet light source (for example, an electrodeless UV lamp) that arranges both the ultraviolet light source and the heat source in the ultraviolet irradiation device 26 or generates high heat together with the ultraviolet light may be used. With such a configuration, the effect of improving the interfacial adhesion can be obtained by heating without increasing the steps of the method of manufacturing the coated optical fiber 10.

  Moreover, you may perform a heating process before an ultraviolet irradiation process. Specifically, the heating device 29 may be disposed in the vicinity of the resin coating device 24 to heat the die from which the coating material is discharged. Alternatively, the heating device 29 may be disposed between the resin coating device 24 and the ultraviolet irradiation device 26 to heat the glass optical fiber 11 before resin curing. Even with such a configuration, the effect of improving the interfacial adhesion by heating can be obtained.

  Further, a heating step may be performed after the coated optical fiber 10 is manufactured. Specifically, after the coated optical fiber 10 is manufactured by the manufacturing method according to the first embodiment, heating may be performed by placing the coated optical fiber 10 in a thermostat set to a predetermined temperature. Thereby, the improvement effect of the interface adhesive force by heating can be acquired, without changing the manufacturing apparatus 20 from 1st Embodiment.

(Example)
As examples and comparative examples according to the above-described embodiment, samples were prepared under the following conditions, and their properties were measured.

1. Blending of coating material As a UV curable resin for the coating material, a UV curable polyether urethane acrylate resin was used. The Young's modulus was adjusted to 1.0 MPa by changing the molecular weight of the polyether moiety in the oligomer, the type and blending amount of the diluted monomer and reactive monomer. As photopolymerization initiator, Lucirin (registered trademark) TPO (BASF, trade name) 3.0 wt% is used, and silane coupling agent KBM-5103 (Shin-Etsu Chemical Co., trade name) 1.5 wt% is used. used.

  As a photoacid generator to be added to the coating material, diphenyl [4- (phenylthio) phenyl] sulfonium hexafluoroantimonate (manufactured by San Apro, trade name CPI-101A), or 4-isobutylphenyl (4-methylphenyl) iodonium. Hexafluorophosphate (manufactured by BASF, trade name: IRGACURE250) was used. In addition, in addition to the photoacid generator CPI-101A, the coating materials of some examples include 1-naphthylmethylmethyl-p-hydroxyphenylsulfonium hexafluoroantimonate (Sanshin) as a thermal acid generator. Chemical Industry, trade name SI-60, decomposition temperature 60 ° C.) was added. In each Example and Comparative Example, the type and amount of the acid generator added to the coating material were variously set as shown in Table 1 described later.

2. Production of Film A plate-like glass substrate was spin-coated with a coating material according to each Example and Comparative Example at a thickness of 100 μm. The prepared sample was put in a purge box to make a nitrogen atmosphere, and irradiated with ultraviolet rays by adjusting the illuminance and speed so that the accumulated light amount was 500 mJ / cm ² with a conveyor type ultraviolet irradiation device. The coating material cured in this manner was used as a film according to each example and comparative example. An electrodeless UV lamp (D bulb) was used as a light source of the conveyor type ultraviolet irradiation device.

3. Measurement of Young's modulus The Young's modulus (tensile modulus) of the film was used to determine the curability of the coating material. The film according to each Example and Comparative Example was peeled off from the glass substrate, cut into a 6 mm width and formed into a strip shape, and 2.5% modulus thereof was measured according to JIS K7161.

4). Measurement of glass adhesion strength Glass adhesion strength was used to determine the adhesion strength of the interface between the coating material and the glass substrate. The film according to each Example and Comparative Example was cut into a width of 10 mm, and the force when peeled from the glass substrate by pulling from the surface of the glass substrate at a normal temperature of 50 mm / min. did. The measurement was carried out under three conditions 1, 3, and 7 days after film production.

Table 1 shows the conditions and measurement results of each Example and Comparative Example.

  In Examples 1 to 4, by adding a sulfonium salt photoacid generator (CPI-101A) to the coating material, higher glass adhesion can be obtained in a shorter time than when no photoacid generator is added. Was confirmed. In Examples 5 to 6, by adding an iodonium salt-based photoacid generator (IRGACURE250) to the coating material, higher glass adhesion can be obtained in a shorter time than when no photoacid generator is added. Was confirmed. In any of Examples 1 to 6, the Young's modulus is maintained at about 1.0 MPa, and the photoacid generator does not affect the curability of the resin.

  In Comparative Example 1 in which the photoacid generator is not added to the coating material, a high glass adhesion is obtained by the action of the silane coupling agent, but the glass adhesion is small before 3 days from the preparation of the sample. Was confirmed. That is, it takes 3 days or more before high glass adhesion is exhibited without a photoacid generator. Therefore, if a load is applied at a time when the interfacial adhesion is insufficient immediately after the coated optical fiber is manufactured, there is a possibility that problems such as separation of the interface occur.

  In Comparative Example 2 in which no silane coupling agent was added, it was confirmed that high glass adhesion was not obtained despite the addition of the photoacid generator. That is, it can be seen that the effects of the above-described embodiment are exhibited by the presence of both the silane coupling agent and the photoacid generator. Also in Comparative Example 2, the Young's modulus is 1.0 MPa, and the photoacid generator does not affect the curability of the resin.

  In Comparative Example 3 where the amount of photoacid generator (5.0%) is larger than the amount of photopolymerization initiator (3.0%), the Young's modulus is significantly reduced, and sufficient curability of the resin is obtained. There wasn't. This is thought to be because the photoacid generator similarly inhibits the reaction of the photopolymerization initiator that absorbs ultraviolet rays and generates radical species. In Example 4 where the amount of photoacid generator (3.0%) is equal to the amount of photopolymerization initiator (3.0%), the Young's modulus is almost maintained, so the amount of photoacid generator is photopolymerization. It can be said that it is desirable to be less than or equal to the amount of initiator.

  In Example 7 in which the thermal acid generator (SI-60) was added in addition to the photoacid generator (CPI-101A), compared to Example 1 in which the same amount of photoacid generator was added. The glass adhesion rises quickly. Similarly, in Example 8 in which the thermal acid generator is added in addition to the photoacid generator, the initial value of the glass adhesion is slightly improved as compared with Example 3 in which the same amount of photoacid generator is added. ing. This is considered to be because acid is generated also from the thermal acid generator due to radiation heat at the time of ultraviolet irradiation or reaction heat of the resin, and the reaction of the silane coupling agent is promoted.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 10 Covered optical fiber 11 Glass optical fiber 12 Primary layer 13 Secondary layer 14 Covering layer

Claims (10)

UV curable resin,
A silane coupling agent;
A photoacid generator that generates acid upon irradiation with light;
A coating material for optical fiber.   2. The optical fiber coating material according to claim 1, wherein the amount of the photoacid generator is 0.01 wt% or more and 10 wt% or less with respect to the optical fiber coating material. A photopolymerization initiator for initiating polymerization of the ultraviolet curable resin;
The optical fiber coating material according to claim 2, wherein the amount of the photoacid generator is equal to or less than the amount of the photopolymerization initiator.   The at least part of the wavelength region of the light that cures the ultraviolet curable resin and the wavelength region of the light that generates the acid in the photoacid generator overlap each other. The coating material for optical fibers as described in any one of these.   The optical fiber coating according to any one of claims 1 to 4, wherein the photoacid generator contains at least one of an onium salt photoacid generator and a nonionic photoacid generator. material.   The optical fiber coating material according to any one of claims 1 to 5, further comprising a photosensitizer that absorbs light in a wavelength region different from that of the photoacid generator.   The optical fiber coating material according to claim 1, further comprising a thermal acid generator that generates an acid by heat. Glass optical fiber,
A coating layer covering the glass optical fiber;
With
A coated optical fiber, wherein at least one layer constituting the coating layer is made of the coating material for an optical fiber according to any one of claims 1 to 7. Drawing a glass optical fiber;
Coating the glass optical fiber with a coating material containing an ultraviolet curable resin, a silane coupling agent, and a photoacid generator that generates acid upon irradiation with light;
Irradiating the glass optical fiber coated with the coating material with ultraviolet rays to cure the ultraviolet curable resin and generate the acid in the photoacid generator;
A method for producing a coated optical fiber comprising:   The method for manufacturing a coated optical fiber according to claim 9, further comprising a step of heating the coating material.

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