JP2014219550A - Coated optical fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coated optical fiber having high resin breaking elongation, core wire transparency, and side pressure characteristic.SOLUTION: A coated optical fiber 10 includes: at least one glass fiber 13 which has a core part 11 and a clad part 12; and a resin coating layer 16 which coats the outer circumference of the glass fiber 13. The coated optical fiber 10 contains filler containing synthetic quartz as a material in an outermost layer 15 of the resin coating layer 16. The content of the filler is 0.25 to 50 mass%, and the mean particle diameter of the filler is 500 nm or less.

Description

  The present invention relates to an optical fiber core.

Patent Document 1 describes an optical fiber core wire having a resin coating layer on the outer periphery of a glass fiber. Further, Patent Literatures 1 and 2 describe optical fiber tape core wires each including a collective coating resin (connecting material) obtained by integrally covering a plurality of optical fiber core wires arranged in parallel.
An ultraviolet curable resin is used for the resin coating layer and the collective coating resin (connecting material) of the optical fiber core and the optical fiber ribbon described in Patent Documents 1 and 2. The ultraviolet curable resin is obtained by curing an ultraviolet curable resin composition by ultraviolet irradiation.

International Publication No. 02/066390 Pamphlet JP 2002-277700 A

  In the field of optical fibers, an optical fiber having excellent lateral pressure characteristics is required as the density of optical fiber cables increases. In order to improve the optical fiber side pressure characteristics, it is necessary to provide a plurality of resin coating layers on the outer periphery of the glass fiber and to increase the Young's modulus of the outer layer of the plurality of resin coating layers. However, it has been difficult to achieve a high elastic modulus while forming a resin coating layer using only an ultraviolet curable resin and ensuring the handling properties of the optical fiber (maintenance of resin break elongation and core transparency).

  The present invention has been made in view of the above problems in the field of conventional optical fiber cores and the like, and an object thereof is to provide an optical fiber core having high resin break elongation, core wire transparency, and high lateral pressure characteristics. And

The invention of this application 1
(1) An optical fiber core having at least one glass fiber having a core and a clad, and a resin coating layer covering the outer periphery of the glass fiber, and using synthetic quartz as the outermost layer of the resin coating layer It is an optical fiber core wire in which the filler content is 0.25 to 50% by mass and the average particle diameter of the filler is 500 nm or less.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the optical fiber core wire which has the resin coating layer which coat | covers the outer periphery of a glass fiber, and a thing with high resin break elongation, core wire transparency, and a lateral pressure characteristic.

It is a schematic sectional drawing which shows an example (single-core type) of the optical fiber core wire of this invention. It is a schematic sectional drawing which shows another example (optical fiber tape core wire) of the optical fiber core wire of this invention.

[Description of Embodiment of Present Invention]
One form of the present invention is (1) an optical fiber core wire having at least one glass fiber having a core and a clad, and a resin coating layer covering the outer periphery of the glass fiber, The outermost layer contains a filler made of synthetic quartz as a raw material, the filler content is 0.25 to 50% by mass, and the filler has an average particle diameter of 500 nm or less.

In one embodiment of the present invention, the resin coating layer is formed by applying an ultraviolet curable resin composition to the outer periphery of the glass optical fiber and then curing the resin by ultraviolet irradiation.
The ultraviolet curable resin composition is widely used in other fields and various applications other than the optical fiber core wire.
Curing by ultraviolet irradiation of the ultraviolet curable resin composition indicates that, in other words, the portion where ultraviolet rays do not reach becomes insufficiently cured. Therefore, the addition of filler to the UV curable resin composition has not been carried out much, and even if a filler is added, it is limited to the field where the addition amount is small or the cured thickness may be thin. It was. Further, it has been found that the addition of a general filler significantly inhibits the curability.

In one embodiment of the present invention, a filler made of synthetic quartz is used as the filler. As a result, the resin coating layer containing the filler could be made to have a low shrinkage and a high Young's modulus while maintaining its curability. An optical fiber having a high resin breaking elongation, a high core transparency, and a high lateral pressure characteristic by maintaining a low shrinkage rate and a high Young's modulus while maintaining the curability of the resin coating layer containing the filler. I was able to provide a heart line.
The following is presumed as the above-mentioned action, particularly the action of maintaining curability.
By using synthetic quartz as a raw material, the irradiated ultraviolet rays may be absorbed or blocked by the filler even when the ultraviolet rays are irradiated for curing the ultraviolet curable resin composition. However, it is moderately transmitted and, in some cases, moderately scattered. Thereby, ultraviolet rays sufficiently reach the entire molded body of the ultraviolet curable resin composition.

(2) As an example of the optical fiber core wire, there is a so-called single optical fiber core wire which has only one glass fiber and has a plurality of resin coating layers.
(3) As another example of the optical fiber core wire, a plurality of optical fibers coated on the glass fiber are arranged in parallel, and the outermost layer of the resin coating layer collects the plurality of optical fibers together. Thus, there is a so-called optical fiber ribbon that is a coating layer to be connected.

(4) The filler is preferably dispersed by a dispersion medium. Since the filler is dispersed in a dispersion medium, the filler is uniformly dispersed in the ultraviolet curable resin composition for forming the resin coating layer, and other fillers in the ultraviolet curable resin composition are used. It is presumed that the mixing and dispersibility with the components is also improved.

(5) The resin of the layer containing the filler has a linear expansion coefficient of 1.2 × 10 ⁻⁴ / ° C. or lower by normal temperature to low temperature (−50 to 50 ° C.) by thermomechanical analysis (TMA). Is preferred. When the resin of the layer containing the filler has a linear expansion coefficient of 1.2 × 10 ⁻⁴ / ° C. or less by normal temperature to low temperature (−50 to 50 ° C.) by TMA, before and after a heat cycle of −50 to 50 ° C. The change in the transmission loss of light having a wavelength of 1550 nm is preferably 0.5 dB / km or less.

[Details of the embodiment of the present invention]
Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 and 2.
FIG. 1 is a schematic cross-sectional view showing an example of an optical fiber core wire according to an embodiment of the present invention.
The optical fiber core wire 10 is a so-called single-core fiber having a resin coating layer 16 including an inner layer 14 and an outer layer 15 formed of an ultraviolet curable resin composition on the outer periphery of a glass fiber 13 made of a single quartz glass. An optical fiber core. The glass fiber 13 includes a core part 11 and a clad part 12. For example, germanium-added quartz can be used for the core portion 11, and pure quartz or fluorine-added quartz can be used for the cladding portion 12.

  In FIG. 1, for example, the diameter (D2) of the glass fiber 13 is about 125 μm. The diameter (D1) of the core part 11 is preferably about 7 to 15 μm. The resin coating layer 16 includes two layers, an inner layer 14 and an outer layer 15, and the inner layer 14 has a thickness of 12 to 45 μm. The layer containing the filler made of synthetic quartz is the outer layer 15.

FIG. 2 is a schematic cross-sectional view showing an example of an optical fiber ribbon that is another embodiment of the present invention.
The optical fiber ribbon 20 includes a plurality of glass fibers 13 arranged in parallel, and a coating layer (hereinafter also referred to as a connection coating layer) 22 that collectively connects the plurality of glass fibers 13.
In FIG. 2, the connection coating layer 22 is a layer containing a filler made of synthetic quartz. In FIG. 2, the plurality of glass fibers 13 are each coated with a resin coating layer 26 to form a single optical fiber core wire 21. The plurality of optical fiber core wires 21 are integrated by a connection coating layer 22.

  Such an optical fiber ribbon 20 is first conveyed to a coating apparatus in a state where a plurality of single optical fibers are arranged in parallel with each other. The pressurized tank connected to the coating apparatus contains an ultraviolet curable resin composition containing a filler made of synthetic quartz for forming the batch connection coating layer 22 as a raw material. The ultraviolet curable resin composition is supplied from the pressurized tank to the coating device and applied to the optical fiber core. Further, in the curing device provided on the downstream side of the coating device, the ultraviolet curable resin composition applied around the optical fiber core is irradiated with ultraviolet rays to cure the ultraviolet curable resin composition. Thereby, the connection coating layer 22 is formed, and the optical fiber ribbon 20 of this embodiment is obtained.

The optical fiber core 10 or the optical fiber ribbon 20 according to the embodiment of the present invention is set to −50 ° C. for 2 hours and 1 hour to 50 ° C., and to 50 ° C. for 2 hours and 1 hour to −50 ° C. When the change in the transmission loss of light having a wavelength of 1550 nm is measured before and after the heat cycle (−50 ° C. to 50 ° C.), it is preferably less than 0.5 dB / km.
Changes in transmission loss before and after the heat cycle (−50 ° C. to 50 ° C.) of the optical fiber core 10 or the optical fiber ribbon 20 and the normal temperature to low temperature (−50) of the resin containing the filler in the layer containing the filler ˜50 ° C.) The relationship with the linear expansion coefficient was examined. As a result, it was found that the linear expansion coefficient of the resin of the layer containing the filler in which the change in the transmission loss is less than 0.5 dB / km is 1.2 × 10 ⁻⁴ / ° C. or less. The linear expansion coefficient of the coating layer can be adjusted by the filler content and the manner of dispersion.

(Filler made from synthetic quartz)
Examples include fillers made from synthetic quartz used in the embodiment of the present invention, and those produced by pulverizing synthetic quartz into fillers to an appropriate particle size. Further, the filler may contain a trace amount of a component other than synthetic quartz as long as the effects of the present invention are not impaired.
The filler may be directly added to and dispersed in the ultraviolet curable resin composition for forming the resin coating layer, but before that, it is preferable to perform a dispersion treatment by a general method. A general dispersion process is not particularly limited, but a dispersion method using a dispersion medium is simple and efficient. The dispersion medium is not particularly limited, and examples thereof include EO-modified bisphenol A diacrylate, polyethylene glycol diacrylate, PO-modified bisphenol A diacrylate, polypropylene glycol diacrylate, and polytetramethylene glycol diacrylate.

The filler has an average particle size of 500 nm or less, preferably 450 nm or less, and more preferably 400 nm or less. In this case, the primary particle diameter is measured by, for example, microscopic observation, image analysis, or light scattering method.
Content of the said filler in the layer containing the said filler is 0.25-50 mass%, 0.5-25.0 mass% is preferable and 1.0-10.0 mass% is more preferable.

(Base resin)
In an embodiment of the present invention, the ultraviolet curable resin composition for forming the layer containing the filler and the layer not containing the filler contains a base resin.
The base resin is not particularly limited as long as it has ultraviolet curable properties. For example, a resin containing an oligomer, a monomer, a photoinitiator, and a silane coupling agent is preferable.

  Examples of the oligomer include urethane acrylate, epoxy acrylate, or a mixed system thereof.

Examples of the urethane acrylate include those obtained by reacting a polyol compound, a polyisocyanate compound, and a hydroxyl group-containing acrylate compound.
Examples of the polyol compound include polytetramethylene glycol, polypropylene glycol, and bisphenol A / ethylene oxide addition diol. Examples of the polyisocyanate compound include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and isophorone diisocyanate. Examples of the hydroxyl group-containing acrylate compound include 2-hydroxy acrylate, 2-hydroxyethyl acrylate, 2-hydroxybutyl acrylate, 1,6-hexanediol monoacrylate, pentaerythritol triacrylate, 2-hydroxypropyl acrylate, and tripropylene glycol diacrylate. Is mentioned.

  Examples of the monomer include N-vinyl monomers having a cyclic structure, such as N-vinylpyrrolidone, N-vinylcaprolactam, and acryloylmorpholine. The inclusion of these monomers is preferable because the curing rate is improved. In addition, monofunctional monomers such as isobornyl acrylate, tricyclodecanyl acrylate, benzyl acrylate, dicyclopentanyl acrylate, 2-hydroxyethyl acrylate, phenoxyethyl acrylate, polypropylene glycol monoacrylate, polyethylene glycol diacrylate, A polyfunctional monomer such as tricyclodecanediyldimethylene diacrylate or bisphenol A / ethylene oxide addition diol diacrylate is used.

Examples of the photoinitiator include 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 2,4 , 4-trimethylpentylphosphine oxide, 2,4,4-trimethylbenzoyldiphenylphosphinoxide, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one (Irgacure 907, Ciba Specialty Chemicals), 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Lucirin TPO, manufactured by BASF) and the like. Further, an antioxidant, a photosensitizer and the like may be added.
Examples of the silane coupling agent include γ-mercaptopropyltrimethoxysilane.

  Hereinafter, the results of evaluation tests using examples and comparative examples according to the present invention will be shown, and the present invention will be described in more detail. The present invention is not limited to these examples.

[Fabrication of optical fiber core wire 10]
As the glass fiber 13, a core mainly composed of quartz having a core diameter (D1) of 8 μm and a cladding diameter (D2) of 125 μm (relative refractive index difference Δn is 1.0%) was used. Then, the outer peripheral surface of the glass fiber 13 is coated with two coating layers 16 (an inner layer 14 and an outer layer 15) obtained by curing the following ultraviolet curable resin composition according to the method described above, and the inner layer 14 An optical fiber core wire 10 having an outer diameter of 180 μm and an outer layer 15 having an outer diameter (D3) of 250 μm was produced.

[Ultraviolet curable resin composition for forming inner layer 14]
60% by mass of polymerizable oligomer synthesized from 2-hydroxyethyl acrylate, 2,4-tolylene diisocyanate and polypropylene glycol
N-vinylpyrrolidone 7% by mass
Isobornyl acrylate 15% by mass
Isostearyl acrylate 15% by mass
2,4,4-Trimethylbenzoyldiphenylphosphinoxide 2% by mass
γ-mercaptopropyltrimethoxysilane 1% by mass

[UV curable resin composition for forming outer layer 15]
2.5 parts by mass of 2,4,4-trimethylbenzoyldiphenylphosphinoxide, which is a photoinitiator, with respect to 100 parts by mass of the base resin 1 having the following composition, filler type, particle size range and addition The amount and the addition amount of the dispersion medium were blended so as to satisfy the conditions described in Table 1 below.
In “filler dispersion”, “preliminary” means that the dispersion was prepared by previously dispersing the filler in the dispersion medium and then blended with the base resin 1 or the like, and “directly” means that the filler and the dispersion medium were mixed. And without separately preparing the dispersion liquid, it means that the base resin 1 was blended separately.
As a dispersion medium, A-BPE-30 (EO modified number 30) manufactured by Shin-Nakamura Chemical Co., Ltd., which is an EO-modified bisphenol A diacrylate, was used.

[Base resin 1]
Polymerizable oligomer synthesized from 2-hydroxyethyl acrylate, 2,4-tolylene diisocyanate and diol type polypropylene glycol 55% by mass
Isobornyl acrylate 13% by mass
N-Vinylcaprolactam 15% by mass
Tripropylene glycol diacrylate 15% by mass
2,4,4-Trimethylbenzoyldiphenylphosphinoxide 2% by mass

[Evaluation of optical fiber core wire 10]
The following evaluation tests (linear expansion coefficient, lateral pressure characteristics, curability of the outer layer 15) were performed on the manufactured optical fiber core wire. The results are shown in Table 1 below.

(Linear expansion coefficient evaluation method)
The linear expansion coefficient at −50 to 50 ° C. of the resin composition that becomes the outermost layer of the optical fiber core wire was measured by a thermomechanical analysis (TMA) (film test).
Further, before and after the heat cycle (−50 ° C. to 50 ° C.) in which the optical fiber core wire is set to −50 ° C. for 2 hours and set to 50 ° C. over 1 hour, and then set to 50 ° C. for 2 hours and set to −50 ° C. over 1 hour. A change in transmission loss of an optical signal having a wavelength of 1550 nm propagating through the optical fiber was measured. If the change in transmission loss was 0.5 dB / km or more, it was judged as NG.
Looking at the relationship between the linear expansion coefficient of the resin (film state) that is the outermost layer of the optical fiber and the change in transmission loss, if the linear expansion coefficient is 1.2 × 10 ⁻⁴ / ° C. or less, the change in transmission loss is 0.5 dB. It was smaller than / km and OK.

(Side pressure characteristics evaluation method)
An optical fiber 10 to be tested was wound in a single layer with a tension of 80 g around a 280 mm diameter bobbin whose surface was covered with sandpaper, and loss was measured by an OTDR (Optical Time Domain Reflectometer) method.
The optical fiber core 10 to be tested was a single mode optical fiber conforming to G652, and had an MFD (mode field diameter) of 10.4 μm.
Using the measured loss,
Formula: Δα (dB / km) = loss (with sandpaper) −loss (without sandpaper)
The calculated Δα was evaluated according to the following criteria. A and B were accepted.
(Evaluation criteria)
Δα ≦ 0.1 dB / km: A
0.1 dB / km <Δα <0.5 dB / km: B
Δα ≧ 0.5 dB / km: C

(Curing property evaluation method)
Using a UV-curable resin composition for the outer layer 15 formed, respectively to create a resin cured sheet by UV irradiation of 30 mJ / cm ² and 300 mJ / cm ^2, the shape of the test piece 1A in JIS K7162, the thickness and 100μm did. The elastic modulus of each of the cured resin sheet prepared was measured, the 30 mJ / cm ² modulus of the cured resin sheet was cured by ultraviolet irradiation amount and 300 mJ / cm ² modulus of the cured resin sheet was cured by ultraviolet irradiation dose The ratio was calculated. The ratio was evaluated as B when less than 0.80 and A when 0.80 or more.

(Comprehensive evaluation)
The evaluation result of the side pressure characteristic is A or B, and the evaluation result of the curability is A.
In Table 1 below, no. 1 to 4 are examples. 5 to 9 are comparative examples.

From the above results, it was confirmed that when the outer layer 15 contains a specific amount of filler made of synthetic quartz having a specific particle size range, the lateral pressure characteristics, the linear expansion coefficient, and the curability are all good.
On the other hand, when the outer layer 15 does not contain a filler made of synthetic quartz, the outer layer 15 contains a synthetic quartz filler outside a specific particle size range, and the synthetic quartz filler content is outside a specific range, the lateral pressure characteristics, All of the linear expansion coefficient and curability could not be improved.
In addition, No. In No. 8, since the outer layer 15 was not cured, the side pressure characteristics could not be evaluated.

[Fabrication of optical fiber ribbon 20]
An optical fiber is used under the same conditions as in the above-mentioned “Fabrication of optical fiber core 10” except that the “UV curable resin composition for forming outer layer 15” does not contain a filler and a dispersion medium. A single-core optical fiber 21 used for the tape core 20 was produced. The core used for the optical fiber tape was obtained by applying and curing colored ink to the optical fiber core 21.
Four of the optical fiber cores 21 produced as described above were wound around four reels of an optical fiber feeding supply, and were sequentially transferred to a wire concentrator, a coating device, and a curing device. An ultraviolet curable resin composition A having the following composition was applied to these optical fiber cores with a coating apparatus. The connection coating layer 22 was formed by irradiating ultraviolet rays with a curing device to cure the ultraviolet curable resin composition A. As a result, a four-core optical fiber ribbon 20 shown in FIG. 2 was obtained. The linear velocity of the optical fiber core 21 when passing through the curing device was 600 m / min.

[Ultraviolet curable resin composition A]
It compounded so that the particle size range and addition amount of a synthetic quartz filler, and the addition amount of a dispersion medium may become the conditions of following Table 2 with respect to 100 mass parts of base resin 2 which consists of the following composition.
In “filler dispersion”, the meanings of “preliminary” and “direct” are the same as described above.
Moreover, A-BPE-30 (EO organization number 30) by Shin-Nakamura Chemical Industry which is EO modified bisphenol A diacrylate was used as a dispersion medium.

[Base resin 2]
Urethane acrylate obtained by reacting 1 mol of bisphenol A / ethylene oxide addition diol, 2 mol of tolylene diisocyanate and 2 mol of hydroxyethyl acrylate
Urethane acrylate obtained by reacting 18 parts by mass of polypropylene glycol 1 mol, tolylene diisocyanate 2 mol and hydroxyethyl acrylate 2 mol
30 parts by mass of urethane acrylate obtained by reacting 1 mol of tolylene diisocyanate and 2 mol of hydroxyethyl acrylate
10 parts by weight tricyclodecane diacrylate 15 parts by weight N-vinylpyrrolidone 10 parts by weight isobonyl acrylate 10 parts by weight bisphenol A / ethylene oxide addition diol diacrylate
5 parts by mass 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one (Irgacure 907, manufactured by Ciba Specialty Chemicals)
0.7 parts by mass 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Lucirin TPO, manufactured by BASF)
1.3 parts by mass

[Evaluation of optical fiber ribbon 20]
The produced optical fiber ribbon 20 was subjected to the same evaluation test (linear expansion coefficient, lateral pressure characteristics, curability of the connecting coating layer 22) as that of the optical fiber 10 described above. The results are shown in Table 2 below.
In Table 2 below, No. Nos. 11 to 12 are examples. 13 is a comparative example.

From the above results, it was confirmed that by including a specific range amount of synthetic quartz filler having a specific particle size range in the connection coating layer 22, the lateral pressure characteristics, the linear expansion coefficient, and the curability are all good.
On the other hand, when the connection coating layer 22 does not contain a synthetic quartz filler, the lateral pressure characteristics, the linear expansion coefficient, and the curability cannot all be improved.

DESCRIPTION OF SYMBOLS 10, 21 Optical fiber core wire 11 Core part 12 Clad part 13 Glass fiber 14 Inner layer 15 Outer layer 16, 26 Resin coating layer 20 Optical fiber tape core wire 22 Connection coating layer

Claims (5)

An optical fiber core having at least one glass fiber having a core and a clad, and a resin coating layer covering an outer periphery of the glass fiber,
An optical fiber core containing a filler made of synthetic quartz as an outermost layer of the resin coating layer, wherein the filler content is 0.25 to 50% by mass, and the average particle diameter of the filler is 500 nm or less. line.   The optical fiber core wire according to claim 1, wherein the optical fiber core wire has only one glass fiber and the resin coating layer has a plurality of layers.   2. The optical fiber according to claim 1, wherein a plurality of optical fibers in which the glass fiber is coated with a resin are arranged in parallel, and an outermost layer of the resin coating layer is a coating layer that collectively connects the plurality of optical fibers. Heartline.   The optical fiber core wire according to any one of claims 1 to 3, wherein the filler is dispersed by a dispersion medium. The resin of the layer containing the filler has a linear expansion coefficient of 1.2 × 10 ⁻⁴ / ° C. or less according to TMA (thermomechanical analysis) at normal temperature to low temperature (−50 to 50 ° C.). An optical fiber core wire according to claim 1.

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