JP4190975B2 - Optical fiber, optical fiber ribbon using the optical fiber, and optical fiber cable using the optical fiber or optical fiber ribbon - Google Patents

Description

  The present invention relates to an optical fiber strand excellent in fatigue characteristics, an optical fiber ribbon using the optical fiber strand, and also installed in a cave or an aerial space formed using the optical fiber strand or the optical fiber ribbon. The present invention relates to an optical fiber cable.

  In recent years, the demand for FTTH (Fiber to the home) has been increasing rapidly due to an increase in demand for large-capacity data transmission and a dramatic increase in the amount of personal communication lines typified by the Internet. There is an urgent need to establish a fiber optic cable network.

As a general optical fiber cable used for constructing an optical fiber cable network, for example, a slot type optical fiber cable is known.
In this cable, a plurality of optical fiber strands are arranged in parallel in a plane, and a plurality of optical fiber ribbons, which are integrated into a tape shape, are laminated in a spiral shape on the surface, or as appropriate. This is a structure in which a slot whose spiral direction is reversed at intervals is provided, and a so-called slot is accommodated in the groove.

FIG. 1 is a schematic cross-sectional view of a normal optical fiber used in such an optical fiber cable.
As shown in FIG. 1, this optical fiber strand 1 is made of quartz glass or multicomponent glass, for example, a glass optical fiber 2 having a core and a cladding provided outside the core (hereinafter simply referred to as an optical fiber 2). The primary coating layer 3 made of, for example, an ultraviolet curable resin is coated on the outside, and the secondary coating layer 4 also made of an ultraviolet curable resin is formed on the outside.

By the way, the above-described optical fiber cable is usually laid in a cave, an aerial, or the like. The installed optical fiber cable may be in a state where tension is always applied depending on the installed condition. In such a case, a part of this tension may continue to act on the optical fiber 1 constituting the optical fiber cable for a long period of time.
If tension is applied continuously for a long time in this way, so-called fatigue failure, in which the optical fiber strand breaks suddenly after a certain period of time, or breaks when a little larger tension is further applied. It may happen.
It is presumed that this is because the defects on the glass surface forming the optical fiber are hydrolyzed by moisture, and corrosion grows in a state in which tension is applied as described above, that is, a so-called stress load condition.

In order to avoid such fatigue failure, it is necessary to improve the fatigue characteristics of the optical fiber 1. By the way, the fatigue characteristic of the optical fiber 1 is greatly affected by the properties of the coating layer covering the surface of the optical fiber 2 shown in FIG. 1, and in the example shown in FIG. 1, the coating material of the primary coating layer 3 and the secondary coating layer 4. It is known to be affected.
Specifically, in order to improve the fatigue characteristics, a silane coupling agent is already added to the coating material of the primary coating layer 3 to improve adhesion to the glass, or the moisture permeability of the coating material of the secondary coating layer 4. Attempts have been made to slow down the hydrolysis of the glass due to moisture by lowering the value.

  However, even though this method can reduce the moisture transmission rate to some extent, this is not sufficient when the optical fiber cable is laid under high humidity, and it may extend the life of the optical fiber cable. No effect has been obtained so far.

Therefore, in the optical fiber 1 in which a coating layer made of an ultraviolet curable resin is provided on the outside of the optical fiber 2 shown in FIG. (Patent Document 1).
Specifically, an ultraviolet curable resin having a pH of 4.5 or less is used as a coating material for the primary coating layer 3 in FIG.
According to Patent Document 1, when the pH of the primary coating layer 3 made of an ultraviolet curable resin in contact with the surface of the optical fiber 2 is set to 4.5 or less, specifically, the dynamic fatigue of the optical fiber strand 1 is determined. The coefficient n value is 18 or more, and the optical fiber 1 having excellent fatigue characteristics can be obtained.

JP 2003-4993 A

By the way, when the optical fiber element 1 of the primary coating layer 3 made of an ultraviolet curable resin is manufactured by the proposal disclosed in the above-mentioned Patent Document 1, and the fatigue characteristics are actually evaluated, the dynamic fatigue coefficient n value immediately after the manufacturing is surely When the pH of the coating material forming the primary coating layer 3 is 4.5 or less, a high value, specifically, a value of 18 or more is obtained.
However, if the optical fiber 1 is left in a high temperature and high humidity for a long time, the coating material for forming the secondary coating layer 4 made of an ultraviolet curable resin has a high pH value. Some had a low dynamic fatigue coefficient n value.

  Therefore, as in the above-mentioned Patent Document 1, simply by making the pH of the coating material that is in contact with the optical fiber 2, that is, forming the primary coating layer 3, 4.5 or less, excellent fatigue characteristics are desired over a long period of time. There was a problem that the optical fiber 1 could not always be obtained.

  Accordingly, an object of the present invention is to form an optical fiber having high fatigue characteristics over a long period of time, an optical fiber ribbon using such an optical fiber, and further using these optical fiber and optical fiber ribbon. An object of the present invention is to provide an optical fiber cable having excellent fatigue characteristics over the long term.

To achieve the above object, the optical fiber of the present invention according to claim 1 comprises at least a glass optical fiber having a core and a cladding, and a urethane acrylate UV curable resin applied to the outside of the glass optical fiber. An optical fiber having a two-layer coating layer, which is a photoinitiator used for the urethane acrylate-based ultraviolet curable resin, and forms light by reacting with oxygen and moisture contained therein after cleavage. by using the initiator, it is characterized in that it has a pH of said optical fiber and 5.5 or less.

Thus, according to the optical fiber of the present claim 1 comprising, it is possible to provide an optical fiber capable of maintaining a high fatigue characteristics desired I was I-term.

The optical fiber of the present application according to claim 2 is characterized in that it has a pH of said optical fiber and 5.0 or less.
Thus the pH of the optical fiber 5.0 below, it is possible to provide an optical fiber capable of maintaining a high fatigue characteristics desired I was I more reliably long.

The optical fiber ribbon according to claim 3 of the present application is a plurality of optical fiber strands according to claim 1 or claim 2 or a plurality of the optical fiber strands with a colored layer arranged in parallel in a planar shape. It is characterized by integrating.
Thus, if an optical fiber ribbon is formed using an optical fiber, an optical fiber ribbon capable of maintaining excellent fatigue characteristics over a long period of time can be obtained.

The optical fiber cable according to claim 4 of the present invention is formed using at least one of the optical fiber strand according to claim 1 or claim 2 or the optical fiber ribbon according to claim 3. It is.
Thus, if an optical fiber cable is formed using the optical fiber strand of this invention and the optical fiber ribbon formed using this, the optical fiber cable which can maintain a high fatigue characteristic over a long period of time can be provided.

As described above, according to the present invention, as a photoinitiator used for the urethane acrylate ultraviolet curable resin, by using a photoinitiator that reacts with oxygen and moisture contained therein to form an acid after cleavage, Since the pH of the optical fiber is 5.5 or less, preferably 5.0 or less, the pH of the glass surface can be kept low over a long period of time, and the fatigue characteristics are maintained high over a long period of time. be able to. Accordingly, an optical fiber strand having high fatigue characteristics over a long period of time, an optical fiber ribbon using such an optical fiber strand, and a long-term fatigue formed using these optical fiber strands and optical fiber ribbons. An optical fiber cable having excellent characteristics can be provided.

  Hereinafter, embodiments of the optical fiber of the present invention will be described in detail with reference to FIG. 1, FIG. 2 and FIG.

FIG. 1 is a schematic diagram showing a cross section of a typical optical fiber according to the present invention.
As shown in FIG. 1, on the outside of an optical fiber 2 made of quartz glass having a core and a cladding provided outside the core, a primary coating layer 3 made of an ultraviolet curable resin, and the primary coating layer 3 An optical fiber strand 1 was obtained by coating the outer coating layer with a secondary coating layer 4 made of an ultraviolet curable resin.
Specifically, as the primary coating layer 3, the pH is adjusted by adding one of the urethane acrylate UV curable resin with or without an amine additive, and two types of photoinitiators A and B. The coating material changed to 3.9 to 5.4 was applied onto the optical fiber 2 by a general-purpose method, and this was irradiated with ultraviolet rays to be cured and coated.

Moreover, the secondary coating layer 4 has a pH of 4.5 to 6 by combining various combinations of urethane acrylate ultraviolet curable resins with or without amine photoinitiators and amine antioxidants added. 1 and these were coated on the primary coating layer 3 in the same manner as the primary coating layer 3.
Specific photoinitiators used are shown below.
Photoinitiator A 2,4,6-Trimethylbenzoylphenylphosphine oxide
(Lucirin TPO manufactured by BASF)
Photoinitiator B 1-Hydroxycyclohexyl phenyl ketone
(Ciba Specialty Chemicals)
Irgacure 184)
Amine-based additive Diethylamine Amine-based photoinitiator 2-Methyl 1- [4-methylthio] phenyl-2-morpholinopropan 1-one
(Ciba Specialty Chemicals)
Irgacure 907)
Amine-based antioxidant hindered amine (HALS)

The dimensions of the optical fiber 2, the primary coating layer 3, and the secondary coating layer 4 of the optical fiber 1 thus obtained are as follows.
The optical fiber 2 is a single-mode optical fiber made of quartz glass and having an outer diameter of 125 μm. The next coating layer 4 was applied. The outer diameter of the coated optical fiber 1 is 245 μm.
As described above, eight types of optical fiber wires 1 of Examples 1 to 8 shown in FIG. 2 were obtained.

Samples were prepared by cutting the optical fiber strands 1 of Examples 1 to 8 obtained in this manner into a length of about 10 mm.
Each sample was weighed to 3 g excluding the weight of quartz glass corresponding to the weight of the optical fiber 2, and then adjusted to pH 7.0 with 0.1N hydrochloric acid and 0.1N sodium hydroxide solution. The flask was placed in a flask containing 30 ml of exchanged water and left in a thermostatic bath maintained at 80 ° C. for 18 hours, and then returned to room temperature and stirred.
Thereafter, only the solution in the flask was transferred to a beaker, and the pH of this solution was measured using a pH meter (for example, MP220 manufactured by METTLER TOLEDO). The pH measured at this time was taken as the pH of the optical fiber 1, that is, the pH of the optical fiber 1 in the state where both the primary coating layer 3 and the secondary coating layer 4 were coated. The measurement results are shown in the pH column of FIG.

  On the other hand, each of the optical fiber strands 1 of Examples 1 to 8 is cut into two, one is left in room temperature and humidity, and the other is left in a constant temperature and humidity atmosphere at a temperature of 85 ° C. and a relative humidity of 85% for 30 days. I left it alone. An optical fiber 1 taken out from a constant temperature and humidity atmosphere after 30 days (hereinafter referred to as an optical fiber 1 after aging) and an optical fiber 1 left in a room temperature and humidity (hereinafter simply referred to as a room temperature product) Each dynamic fatigue coefficient n value was measured according to the method of IEC 60793-1-33. The results are shown in FIGS.

FIG. 3 is a graph showing the relationship between the pH and the dynamic fatigue coefficient n value of the optical fiber 1 after standing at room temperature and after aging. From FIG. 3, there is a correlation between the pH of the optical fiber 1 and the dynamic fatigue coefficient n value. When the pH of the optical fiber 1 is 5.5 or lower, the dynamic fatigue coefficient n value is 18 or higher. It can be seen that the characteristics are obtained.
Incidentally, if the pH of the optical fiber 1 is 5.0 or less, the dynamic fatigue coefficient n value including the dynamic fatigue coefficient n value after aging can be increased to a high value of 20 or more, which is preferable.
By the way, the pH values described in the columns of the primary coating layer and the secondary coating layer in FIG. 2 are the urethane acrylate ultraviolet curable types for the primary coating layer 3 and the secondary coating layer 4 coated on the optical fiber 2. The same coating material as the resin is cast on a glass plate and cured by irradiating it with ultraviolet rays in an amount of 200 mJ / cm ² to form a sheet having a thickness of 200 μm. It is a value measured in the same manner as the pH measurement.

As shown by the pH value of the primary coating layer 3 and the dynamic fatigue coefficient n value in FIG. 2, it can be seen that the desired high fatigue characteristics cannot be obtained even if the pH of the primary coating layer 3 is decreased. In other words, it is understood that it is necessary to select a coating material for the optical fiber 2 in consideration of not only the pH of the primary coating layer 3 but also the pH of both the primary coating layer 3 and the secondary coating layer 4.
When the coating material is selected so that the pH of the optical fiber to which the primary coating layer 3 and the secondary coating layer 4 are applied, that is, the optical fiber 1 is 5.5 or less, as shown in FIGS. It can be seen that even after aging, an optical fiber 1 having excellent fatigue characteristics with a dynamic fatigue coefficient n value of 18 or more can be obtained.

  By the way, in this invention, it is not the pH of the whole coating layer which combined the primary coating layer 3 and the secondary coating layer 4, but the optical fiber strand containing the optical fiber 2 in addition to these primary coating layers 3 and the secondary coating layer 4 It is extremely difficult to completely peel off the primary coating layer 3 and the secondary coating layer 4 from the optical fiber 2, and the optical fiber 2 and the coating layer are separated. This is because there is a great possibility that the pH measurement will be inaccurate.

The form of the optical fiber 1 that can be applied to the present invention is not particularly limited to that shown in FIG. Example, another coating layer further composed of a urethane acrylate ultraviolet curable resin on the secondary coating layer 4 as the coating layer, consisting of two or more layers of urethane acrylate ultraviolet curable resin having a tertiary coating layer or the like is specifically A coating layer may be provided. In this case, the pH of the optical fiber 1 referred to in the present invention means that the optical fiber 1 is coated by the method described above with the primary coating layer 3, the secondary coating layer 4 and the tertiary coating layer coated on the optical fiber 2. It shall mean the value which measured pH of 1.

  The material of the optical fiber 2 is not limited to quartz glass but may be multi-component glass, and the outer diameter is not limited to the above-mentioned 125 μm.

By the way, in order to lower the pH of each coating material made of urethane acrylate UV curable resin forming the coating layer, not only the coating material of the primary coating layer 3 but also the pH of the coating material of the secondary coating layer 4 is lowered. There is a need to.
Specifically, as shown in FIG. 2, if the pH of the secondary coating layer 4 is extremely higher than that of the primary coating layer 3, the components on the secondary coating layer 4 side will increase with time. the process proceeds to the primary coating layer 3 side, by raising the pH of the glass interface of the optical fiber 2 thus decreases the fatigue characteristics, and is presumed. Therefore, it is necessary to suppress the pH of the entire optical fiber 1 including the primary coating layer 3 and the secondary coating layer 4 to 5.5 or less, more preferably to 5.0 or less.

Incidentally, as described above, a urethane acrylate-based ultraviolet curable resin is generally used as this kind of low pH resin. And Photoinitiators used in urethane acrylate ultraviolet curable resin, after cleavage, the type containing a carbonyl group of the acetophenone type such as to form an acid by reacting with oxygen or moisture containing preferred.
Specific examples of the photoinitiator include 1-hydroxycyclohexyl phenyl ketone and acyl phosphine oxide. However, a photoinitiator having an amino group such as morpholino is not preferable because it raises the pH after being cured by ultraviolet irradiation.

Further, it is not preferable to use a basic additive having an amino group that easily moves after curing as a stabilizer such as a silane coupling agent or an antioxidant.
It is also possible to use a photoacid generator as a means for lowering the pH after curing. Examples of such a photoacid generator include CGI series manufactured by Ciba Specialty Chemicals.
Again, however, the present invention is not intended to limit the pH of each coating material, the pH of the coated optical fiber 1 is a structure 5.5 or less, preferably to the a pH 5.0 or less It is to select a coating material made of urethane acrylate-based ultraviolet curable resin . In this way, it is possible to obtain the optical fiber 1 that can obtain sufficient fatigue characteristics over a long period of time.

  For example, a colored layer is applied to the above-described optical fiber 1 of the present invention, if necessary, or a protective layer is applied to increase the mechanical strength if necessary, and then a plurality of general-purpose methods are used to assemble a plurality of them. If an optical fiber cable is manufactured, an optical fiber cable that can be used stably over a long period of time, that is, excellent in fatigue characteristics, can be obtained.

  Furthermore, a colored layer or the like is applied to the optical fiber strand 1 or the optical fiber strand 1 of the present invention, and a plurality of the optical fiber strands 1 or the colored layer-attached optical fiber strands 1 are arranged in parallel in a plane, For example, if an optical fiber ribbon is integrated by a general-purpose method such as applying a collective coating layer thereto, an optical fiber ribbon having excellent long-term fatigue characteristics can be provided.

Furthermore, in a state where a plurality of the optical fiber ribbons are laminated, a spiral shape is provided on the surface thereof, or a groove in which the spiral direction is reversed at an appropriate interval is provided. The laminated optical fiber ribbon can be accommodated to form an optical fiber cable called a slot type optical fiber cable. This type of optical fiber cable is extremely effective for construction of an optical fiber cable network for FTTH (Fiber to the home).
Thus, if the optical fiber 1 of the present invention is used, an optical fiber ribbon or an optical fiber cable that can maintain a stable fatigue characteristic for a long period of time can be obtained.

It is a schematic diagram which shows the cross section of the optical fiber strand concerning this invention. It is a table | surface which shows the coating material, pH, dynamic fatigue coefficient n value, etc. of each optical fiber strand of each Example of this invention. It is a graph which shows the relationship between pH and dynamic fatigue coefficient n value in each optical fiber strand of each Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical fiber strand 2 Optical fiber 3 Primary coating layer 4 Secondary coating layer

Claims (4)

An optical fiber having a glass optical fiber having a core and a clad, and at least two coating layers made of a urethane acrylate ultraviolet curable resin applied to the outside of the glass optical fiber, the urethane acrylate type As a photoinitiator used for the ultraviolet curable resin, a photoinitiator that reacts with oxygen and moisture contained therein to form an acid after cleavage is used, so that the pH of the optical fiber strand is 5.5 or less . An optical fiber element characterized by that. Optical fiber according to claim 1, characterized in that the pH of said optical fiber and 5.0 or less.   3. An optical fiber ribbon comprising a plurality of the optical fiber strands according to claim 1 or 2, wherein the optical fiber strands are provided with a colored layer, arranged in parallel in a planar shape. An optical fiber cable formed using at least one of the optical fiber strand according to claim 1 or claim 2 or the optical fiber ribbon according to claim 3.

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