JP2009198706A - Polymer clad coated optical fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polymer clad coated optical fiber that can suppress pistoning under a temperature changing environment and that is also superior in coating removability. <P>SOLUTION: The polymer clad coated optical fiber 5 includes a resin coating layer (overcoat layer) 4 on the outside of a polymer clad primary optical fiber 3 in which a clad layer 2 is composed of ultraviolet light setting fluorinated carbon resin, wherein the resin coating layer (overcoat layer) 4 is formed by hardening resin composition having a crosslinking double bond concentration of 2.3-3.0 mmol/g and containing urethane acrylate based resin or epoxy acrylate based resin. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polymer clad optical fiber core wire. More specifically, the present invention relates to a polymer-clad optical fiber that can suppress pistoning in a temperature change environment and is excellent in coating removal property, and can suppress an increase in transmission loss due to aging in a high temperature environment.

One type of optical fiber is called a hard polymer clad fiber (hereinafter sometimes abbreviated as “HPCF”). The HPCF core wire is composed of a core having a diameter of about 200 μm made of quartz glass such as pure silica, and a clad layer having a thickness of about 15 μm made of a fluorine resin such as an ultraviolet curable fluorinated acrylate resin surrounding the core. An outer diameter of 0.5 mm or 0.9 mm is provided by extrusion coating a resin coating layer made of a fluororesin such as ethylene-tetrafluoroethylene copolymer (ETFE) on an HPCF strand.
This HPCF core wire has high mechanical strength, and is used for short-distance transmission such as intra-office optical wiring by attaching a connector to the optical cord.

By the way, such an HPCF core wire has a problem that transmission loss increases due to the influence of the operating environment temperature. One of the factors that increase the transmission loss is a decrease in the adhesion between the quartz glass core and the fluorine resin cladding layer. Moreover, when the adhesive force between the core and the clad layer is reduced, the clad layer may be peeled off from the core due to an influence when the resin coating layer expands and contracts due to a change in use environment temperature.
Japanese Patent Application Laid-Open No. 2002-201048 (Patent Document 1) discloses a hard polymer clad in which a resin coating layer of fluororesin (ETFE resin) is provided on an optical fiber having a quartz glass core and a fluororesin clad layer. An optical fiber core is disclosed. The optical fiber core has an initial adhesion between the silica glass core and the fluororesin cladding layer of 100 g / mm or more. In addition, when applying a fluororesin liquid that becomes a cladding layer to the core of quartz glass, the inlet temperature is controlled by a cooling gas, thereby improving the adhesion between the two layers and transmission in a wet heat-degraded environment. The patent document discloses that an increase in loss can be prevented.
JP 2002-201048 A

However, under an environment in which the temperature changes (temperature change environment), the ETFE resin forming the resin coating layer contracts, and pistoning (a phenomenon in which when the temperature change is applied, the polymer contracts and the glass fiber protrudes). )). On the other hand, generally, when the adhesion is improved, the coating removability (removability of the resin coating layer when the HPCF core wire is connected to a connector or the like) tends to decrease.
The present invention has been made to solve the above-mentioned problems, and its object is to provide a polymer-clad optical fiber core wire that can suppress pistoning in a temperature change environment and has excellent coating removal properties. It is to be.
Another object of the present invention is to provide a polymer clad optical fiber that can suppress an increase in transmission loss due to aging in a high temperature environment in addition to the above characteristics.

The configuration of the present invention is as follows.
(1) The crosslinkable double bond concentration is 2.3 to 3.0 mmol / g outside the polymer clad optical fiber strand in which the clad layer is made of an ultraviolet curable fluororesin, and urethane acrylate resin Alternatively, a polymer clad optical fiber having a resin coating layer obtained by curing a resin composition containing an epoxy acrylate resin.
(2) The polymer-clad optical fiber according to the above (1), wherein the glass transition point of the resin coating layer is 100 ° C. or more higher than the glass transition point of the cladding layer.
(3) The polymer-clad optical fiber according to (2), wherein the ultraviolet curable fluororesin in the clad layer is a methacrylate fluororesin.

  In the HPCF core wire of the present invention, since the clad layer and the resin coating layer (overcoat layer) surrounding the outer peripheral surface thereof are both made of an ultraviolet curable resin, a strong adhesion force is developed between the layers and the temperature changes. Pistoning in the environment is suppressed. In particular, the resin coating layer contains a urethane acrylate resin or an epoxy acrylate resin, and the crosslinkable double bond concentration considered to be an influencing factor of the shrinkage of the overcoat layer is a specific amount of 2.3 to 3.0 mmol / g. Since the resin composition is cured and formed, pistoning under a temperature change environment is further suppressed, and it has an appropriate coating removal property.

  Further, by increasing the glass transition point of the resin coating layer by 100 ° C. or higher than the glass transition point of the cladding layer, an increase in transmission loss can be further suppressed. In particular, it is preferable that the ultraviolet curable resin for forming the cladding layer is a methacrylate resin. Methacrylate resins generally have higher glass transition points than acrylate resins that are generally used as cladding layer materials, so molecules do not move easily even when exposed to high-temperature environments, and light scattering due to aggregation of fluorine-based segments. This is because it is difficult to occur.

Hereinafter, an example of an embodiment of the HPCF core wire of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the HPCF core wire 5 is made of a core 1 made of quartz glass such as pure silica and an ultraviolet curable fluororesin such as an ultraviolet curable fluorinated acrylate resin surrounding the outer peripheral surface of the core 1. A resin coating layer (hereinafter referred to as “overcoat layer”) 4 made of an ultraviolet curable fluororesin is further provided on the HPCF strand 3 made of the clad layer 2. The overcoat layer 4 is formed by curing a resin composition containing a urethane acrylate resin or an epoxy acrylate resin and having a crosslinkable double bond concentration of 2.3 to 3.0 mmol / g.
Here, “crosslinkable double bond concentration” refers to oligomers and monomers having two or more double bonds (for example, vinyl group or acrylic group) in the molecule in the resin composition forming the overcoat layer 4. The number (mol) of double bonds contained is calculated with respect to 1 g of the base resin.

  Hereinafter, each component contained in the cladding layer 2 and the overcoat layer 4 of the HPCF core wire 5 will be described.

The resin of the clad layer 2 has a low refractive index and can be cured with active energy rays such as ultraviolet rays. Furthermore, by curing this resin composition, it has mechanical strength and has flexibility. However, it is necessary to be a resin from which a cured product having excellent transparency can be obtained. Such resin includes a resin composition composed of a fluorine atom-containing urethane (meth) acrylate compound, a (meth) acrylate compound having a fluorinated polyether in the structure, and a photopolymerization initiator.
The fluorine atom-containing urethane (meth) acrylate compound used in the cladding layer 2 is obtained by reacting the fluorine atom-containing (meth) acrylate compound described in the following group (1) with the diisocyanate compound described in the group (2). Can do.
Specific examples of the fluorine atom-containing (meth) acrylate compound belonging to the group (1) include, for example, 1- (meth) acryloyloxy-3-trifluoromethyl-2-propanol, 1- (meth) acryloyloxy-3. -Perfluoroethyl-2-propanol, 1- (meth) acryloyloxy-3-perfluoro-n-propyl-2-propanol, 1- (meth) acryloyloxy-3-perfluoro-n-butyl-2-propanol 1- (meth) acryloyloxy-3 (2-perfluoro-n-hexyl) ethoxy-2propanol, 2- (meth) acryloyloxy-3 (2-perfluoro-n-hexyl) ethoxy-propanol, and the like.

  Specific examples of the diisocyanate compound belonging to the group (2) include, for example, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, isophorone diisocyanate, methylene bis (4- Cyclohexyl isocyanate), 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate and the like.

  The fluorine atom-containing (meth) acrylate compound having a polyether in the molecular structure includes the fluorine atom-containing (meth) alcohol compound described in the following group (3) and the fluorine atom (meth) acrylate or acrylic described in (1) above. It can be obtained by reacting an acid.

  Specific examples of the fluorine atom-containing (meth) alcohol compound belonging to the group (3) include, for example, 1H, 1H-perfluoro-3,6-dioxaheptan-1-ol, 1H, 1H-perfluoro-3. , 6-Dioxaoctane-1-ol, 1H, 1H-perfluoro-3,6-dioxadecan-1-ol, 1H, 1H-perfluoro-3,6,9-trioxadecan-1-ol, 1H , 1H-perfluoro-3,6,9-trioxaundecan-1-ol and the like.

  In addition, N-vinylcaprolactam, isobornyl acrylate, nonanediol acrylate, nonylphenol acrylate as a polymerizable unsaturated monomer, the following photopolymerization initiator, and tetrakis {methylene-3- (3-5-di-t) as other additives -Butyl-4-hydroxyphenyl) propionate} methane, γ-mercaptopropyltrimethoxysilane, 2,2,6,6-tetramethyl-4-piperidyl alcohol and the like, and these compounds and the fluorine atom described above A form in which an urethane-containing (meth) acrylate compound and a fluorine atom-containing (meth) acrylate compound are appropriately mixed to form an ultraviolet curable resin liquid, and this resin liquid is irradiated with ultraviolet rays (preferably using a die coating method) Is preferred.

  The photopolymerization initiator used in the ultraviolet curable resin of the cladding layer 2 is required to have good storage stability after blending. Specific examples of such a photopolymerization initiator include, for example, 2-hydroxy-2-methyl-1-phenylpropan-1-one, diethoxyacetophenone, benzyldimethyl ketal, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-2-morpholino (4-thiomethylphenyl) propan-1-one and the like can be mentioned.

The overcoat layer 4 includes a urethane acrylate resin or an epoxy acrylate resin.
As urethane acrylate resin and epoxy acrylate resin, urethane acrylate obtained by reacting bisphenol A / ethylene oxide addition diol, tolylene diisocyanate and hydroxyethyl acrylate; reacting polytetramethylene glycol, tolylene diisocyanate and hydroxyethyl acrylate Urethane acrylate obtained; oligomer selected from urethane acrylate obtained by reacting tolylene diisocyanate and hydroxyethyl acrylate, and tricyclodecane diacrylate; N-vinylpyrrolidone; isobornyl acrylate; bisphenol A / ethylene oxide addition diol Diacrylate lauryl acrylate; bisphenol A epoxy diacryl ; It can be a diluting monomer selected from ethylene oxide adduct of nonylphenol acrylate may appropriately combined. These structural components may be used individually by 1 type, and may be used in combination of 2 or more type. Moreover, a polysiloxane compound can also be added and used for these structural components.

  Further, the overcoat layer 4 may further contain other components such as the polymerizable unsaturated monomer and the photopolymerization initiator mentioned above as an additive for the cladding layer 2. Moreover, as a photoinitiator used with the ultraviolet curable resin of the overcoat layer 4, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, 2, 4, 6 -Trimethylbenzoyldiphenylphosphine oxide can be preferably used.

The preferable dimension of each layer which comprises the HPCF core wire 5 is shown below.
Outer diameter of core 1: 200 μm or less Outer diameter to cladding layer 2: 230 μm or less Outer diameter to overcoat layer 4: 500 μm or more and 900 μm or less

  In the HPCF core wire 5, the thickness of the overcoat layer 4 is preferably 100 μm or more.

  The present invention will be described in more detail with reference to the following examples, but of course the scope of the present invention is not limited thereto.

(Adjustment of UV curable resin composition)
An ultraviolet curable resin composition A having the following composition is prepared.
<Ultraviolet curable resin composition A>
(Base resin component)
-Urethane acrylate obtained by reacting bisphenol A-ethylene oxide addition diol, tolylene diisocyanate and hydroxyethyl acrylate-Urethane acrylate obtained by reacting 1 mol of polytetramethylene glycol, 2 mol of tolylene diisocyanate and 2 mol of hydroxyethyl acrylate-Tri Urethane acrylate, tricyclodecanediacrylate, N-vinylpyrrolidone, isobornyl acrylate (photopolymerization initiator) obtained by reacting 1 mol of diisocyanate and 2 mol of hydroxyethyl acrylate
Bisphenol A Ethylene oxide-added diol diacrylate 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one (Irgacure 907, manufactured by Ciba Specialty Chemicals)
・ 2,4,6-Trimethylbenzoyldiphenylphosphine oxide (Lucirin TPO, manufactured by BASF)

  The crosslinkable double bond group concentration is adjusted by changing the blending amount of bisphenol A / ethylene oxide addition diol.

(Manufacturing of HPCF core wire (1))
The HPCF core wires of Examples 1 to 3 and Comparative Examples 1 to 3 shown in Table 1 are manufactured by the following manufacturing method.

First, the core glass base material is drawn by heating, followed by applying a fluorinated methacrylate-based UV curable resin (clad material resin) with a coating device, and then irradiating the UV with a curing device to cure the resin. The clad layer is then wound up once (core diameter is 200 μm). The cladding diameter is 230 μm. An HPCF strand consisting of a core and a clad layer is passed through a coating device, and an acrylate-based ultraviolet curable resin (the ultraviolet curable resin composition A (resin of overcoat material) prepared as described above) is applied. The overcoat layer is formed by irradiating ultraviolet rays and curing the ultraviolet curable resin. As the ultraviolet curable resin, one having a viscosity of 1000 to 2000 Pa · s at 40 ° C. (temperature during application) is used. The obtained HPCF core wire (outer diameter 500 μm) is wound up by a winder.
As a production method other than the above, there is a tandem method in which both the coating and curing steps of the clad layer and the coating and curing steps of the overcoat layer are performed at the same time in one time, which is preferable in terms of productivity.

(Manufacture of HPCF core wire (2))
The HPCF core wire of Example 4 is manufactured by the same composition and method except that the clad layer is changed from fluorinated methacrylate to fluorinated acrylate in Example 2.

(Evaluation of HPCF core wire)
In order to evaluate the pistoning characteristics under the temperature change environment, the coating removal property, and the heat resistance (the transmission loss amount due to aging under the high temperature environment) in the HPCF core wire obtained in this way, the following test is performed.

<Pistoning characteristics>
Conduct a heat shock test at -40 to 125 ° C. Both ends of the obtained HPCF core wire are cut and cut cleanly (with a blade or the like), held in a −40 ° C. test bath for 30 minutes, immediately transferred to a 125 ° C. test bath, and held for 30 minutes. This is repeated 1000 cycles as one cycle. Thereafter, the protruding amount of the glass fiber or the clad fiber is measured. If the protrusion amount is 30 μm or less, it is judged as good (indicated by “◯” in Table 1), and if it exceeds 30 μm, it is judged as defective (indicated by “X” in Table 1).

<Removability of coating>
Using the tool “Hozan wire stripper P906”, the coating length 10 (mm) of the obtained HPCF core wire is removed. If the coating can be removed, it is judged as good (indicated by “◯” in Table 1), and if the coating cannot be removed, it is judged as defective (indicated by “x” in Table 1).

<Heat resistance (transmission loss increase)>
Evaluation method: An HPCF core wire having a predetermined length (= 1000 m) is prepared. A transmission loss amount (measuring instrument: power tester CAT-7200 manufactured by Sumitomo Electric, measurement wavelength = 650, 850 nm) is measured by the cut-back method.
After leaving at 125 ° C. for 500 hours, if the increase in transmission loss of light at any wavelength of 650 or 850 nm is 5.0 dB / km or less, it is excellent (indicated as “◎” in Table 2), more than 5.0 dB / km and 10 dB / If it is less than km, it is judged as good (indicated by ◯ in Table 2), and if it exceeds 10 dB / km, it is judged as defective (indicated by x in Table 1).

  Table 1 shows the evaluation of the HPCF cords of Examples 1 to 3 and Comparative Examples 1 to 3, and Table 2 shows the evaluation results of Example 4.

  As shown in Table 1, in Examples 1 to 3, good results were obtained for both the pistoning characteristics and the coating removability in a temperature change environment.

  In Comparative Example 1, since the crosslinkable double bond concentration of the overcoat layer was too low, the crosslinking was insufficient and the adhesion strength with the clad layer was insufficient. Accordingly, although the coating removal property was excellent, as a result of the heat cycle, the resin became brittle and pistoning occurred.

  In Comparative Example 2, since the crosslinkable double bond concentration of the overcoat layer is too high, the overcoat layer does not stretch as a result of being exposed to a high temperature, and the overcoat layer collapses when the coating is removed, and part of the overcoat layer remains attached to the cladding layer. The remaining. In addition, it is considered that the overcoat layer was strongly contracted by crosslinking, which is considered to be one of the reasons why it was difficult to remove the coating.

  In Comparative Example 3, an overcoat layer was prepared using ETFE (not including a crosslinkable double bond), which is a thermoplastic resin. occured.

  On the other hand, as shown in Example 4 of Table 2, when the clad layer is made of fluorinated acrylate, compared with Example 2 (clad layer is fluorinated methacrylate) different from Example 4 only in the material of the clad layer, Increase in transmission loss increased. Since acrylate has a lower glass transition point than methacrylate, it is thought that the reason for the increase in transmission loss is that the molecules easily move when exposed to high temperatures and the fluorine-based segments aggregate to form light scattering centers. Nevertheless, the results were practical.

It is a schematic cross section which shows an example of the polymer clad optical fiber core wire of this invention.

Explanation of symbols

  1 core, 2 clad layer, 3 polymer clad optical fiber (HPCF strand), 4 resin coating layer (overcoat layer), 5 polymer clad optical fiber (HPCF core)

Claims (3)

  The crosslinkable double bond concentration is 2.3 to 3.0 mmol / g on the outside of the polymer clad optical fiber whose clad layer is made of an ultraviolet curable fluororesin, and urethane acrylate resin or epoxy acrylate A polymer-clad optical fiber having a resin coating layer formed by curing a resin composition containing a resin.   2. The polymer-clad optical fiber according to claim 1, wherein the glass transition point of the resin coating layer is 100 ° C. or more higher than the glass transition point of the cladding layer.   The polymer clad optical fiber core wire according to claim 2, wherein the ultraviolet curable fluororesin in the clad layer is a methacrylate fluororesin.

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