JP2002116358A - Coated optical fiber tape and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber having sufficiently high single-fiber separation and strength, and capable of sufficiently preventing an increase in transmission loss even when used in water or a humid atmosphere. Provided is a method for manufacturing an optical fiber ribbon, which can efficiently and reliably obtain the optical fiber ribbon. SOLUTION: The optical fiber wires 2a to 2d are covered with inner collective coating layers 3a to 3f made of a first ultraviolet curable resin and integrated to form a multi-core unit 4, and the outer peripheral surface of the multi-core unit 4 is formed as a second core unit. Outer collective coating layer 5 made of UV curable resin
UV curing with a tensile strength of 35 to 65 MPa obtained by curing a resin composition in which the first and second UV curable resins each contain the same UV curable resin in the optical fiber ribbon 1 coated with An optical fiber, wherein the optical fiber is a resin, and the inner collective coating layer is disposed substantially only in a gap formed by the outer peripheral surfaces of the optical fiber strands adjacent to each other and their common tangents. Tape cord.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber ribbon and a method of manufacturing the same, and more particularly, to an optical fiber ribbon in which a plurality of optical fibers arranged in parallel with each other are integrated. It is about lines.

[0002]

2. Description of the Related Art Conventionally, there has been known an optical fiber ribbon in which a plurality of optical fibers are arranged in parallel, and these are covered with a collective coating layer to form one optical fiber.

FIG. 3A is a schematic sectional view showing an example of a conventional optical fiber ribbon. In FIG. 3A,
The optical fiber ribbons 1 are arranged in parallel with each other.
Each of the optical fiber strands 2a to 2d and a collective coating layer 6 that covers and integrates these optical fiber strands. In such an optical fiber ribbon,
By dividing the collective coating layer 6, the optical fiber 2a
~ 2d can be separated into a single core.

In recent years, the introduction of subscriber optical fiber cables has been rapidly progressing, and the development of optical fiber tapes having higher single-core separability and higher strength has been advanced. . For example, Japanese Patent Application Laid-Open No. 1-252020
No. 6, Japanese Patent No. 2763028, Japanese Patent No. 283
No. 9691 discloses an optical fiber in which a plurality of optical fiber wires are covered and integrated with a collective coating layer to form a multi-core unit, and a plurality of multi-core units are further coated and integrated with another collective coating layer. A tape core is disclosed. In the optical fiber ribbon having such a configuration, in order to achieve both the strength of the optical fiber ribbon and the splitting property (single fiber separation), a plurality of optical fiber strands are integrally coated. The collective coating layer for integrating the layer and the multi-core unit is generally made of materials having different hardness and strength.

However, the conventional optical fiber ribbon has a problem that transmission loss is likely to increase when used in water or in a humid atmosphere, regardless of the above-mentioned structure. . For example, when a conventional optical fiber ribbon is immersed in warm water of about 60 ° C. for a long time, the interface between the optical fiber and the collective coating layer partially peels, and water is peeled off at the peeled portion. Accumulation tends to cause partial swelling (blister), and as a result, the optical fiber strand is subjected to microbending in the longitudinal direction thereof, thereby increasing transmission loss.

Therefore, various proposals have been made to avoid such a phenomenon. For example, in Japanese Patent Application Laid-Open No. Hei 7-313324, a coloring layer made of a colored ultraviolet curable resin is provided as a coating layer of an optical fiber, and a plurality of these optical fiber wires are collectively coated with an ultraviolet curable resin. In the optical fiber tape, the adhesive force between the colored layer and the collective coating layer is set to 5 to 20 g / mm by a pulling force per one optical fiber wire. A technique for preventing an increase in transmission loss of a core wire has been disclosed.

In the above-mentioned conventional optical fiber ribbon, the adhesion between the coloring layer and the collective coating layer usually depends on the adhesive strength of the coloring layer and the collective coating layer. And the addition of a release agent to the colorant. Therefore, in such a method, when the adhesion between the colored layer and the collective coating layer is increased, the effect of preventing transmission loss from increasing in water or in a humid environment is improved. At the time of separation, the single-layer separability and strength are reduced, for example, the collective coating layer is hardly peeled off, or the glass fiber is damaged by applying excessive force.

In the case where the adhesion between the colored layer and the collective coating layer is controlled by the degree of surface curing of each layer, it is necessary to keep the intensity of ultraviolet light irradiated when curing the resin in the step of forming each layer constant. However, in actuality, volatile matter generated from an object to be irradiated (such as a coating liquid containing a resin material) due to the irradiation of ultraviolet light adheres to a quartz tube in an ultraviolet irradiation device,
A phenomenon such as a decrease in reflectance due to heating of the mirror for collecting the ultraviolet rays occurs, so that the intensity of the ultraviolet rays decreases with time. Therefore, when manufacturing a large number of optical fiber ribbons, cleaning and cooling of the ultraviolet irradiation device should be performed in order to keep the adhesion between the colored layer and the collective coating layer in each optical fiber ribbon constant. It is necessary to frequently perform the control of the intensity of the ultraviolet light, and the efficiency is significantly reduced.

Japanese Patent Application Laid-Open No. 9-33773 discloses that
An optical fiber ribbon in which the collective coating layer has a water absorption of 1.5% or less as a whole is disclosed. However,
Even with such an optical fiber ribbon, blisters (water droplets) are generated between the colored layer and the collective coating layer, causing partial swelling, which is still sufficient to prevent an increase in transmission loss. It was not something.

Further, Japanese Utility Model Laid-Open Publication No. Sho 61-56612 discloses a collective coating layer 6a to 6f as shown in FIG.
However, a so-called edge bonding type optical fiber ribbon is disclosed, which is disposed only in a gap defined by the outer peripheral surfaces of optical fiber strands adjacent to each other and their common tangents. In the case of the fiber ribbon, the optical fiber is exposed at both ends and the upper and lower surfaces of the fiber ribbon. There has been a problem that cracks are easily generated between the core wires.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, has a sufficiently high single-core separation property and strength, and can be used under water or in a humid atmosphere. Provided is an optical fiber ribbon in which an increase in transmission loss is sufficiently prevented even in a case where the optical fiber ribbon is provided, and a method for manufacturing the optical fiber ribbon that can efficiently and reliably obtain the optical fiber ribbon. The purpose is to do.

[0012]

Means for Solving the Problems The inventors of the present invention have made intensive studies to achieve the above object, and as a result, a plurality of optical fiber wires are covered with an inner collective coating layer and integrated to form a multi-core unit. And further, in an optical fiber ribbon obtained by coating the outer peripheral surface of the multi-core unit with an outer batch coating layer,
As the material of the inner collective coating layer and the outer collective coating layer, an ultraviolet curable resin having a tensile strength of 35 to 65 MPa obtained by curing an ultraviolet curable resin containing the same oligomer is used, and the inner coating layer is substantially formed. When placed only in the gap formed by the outer peripheral surface of the optical fiber and the common tangent thereof adjacent to each other, it is possible to maintain the single core separation and strength at a high level while maintaining the single-core separation and strength in a water or humid atmosphere. It has been found that the increase in transmission loss in the above is sufficiently prevented, and the present invention has been completed.

That is, in the optical fiber ribbon of the present invention, a plurality of optical fiber strands arranged in parallel with each other are covered with an inner batch covering layer made of a first ultraviolet curable resin and integrated to form a multi-core fiber. A unit, and in an optical fiber ribbon obtained by covering the outer peripheral surface of the multi-core unit with an outer batch coating layer made of a second ultraviolet-curable resin, the first ultraviolet-curable resin and the second ultraviolet-curable resin Is an ultraviolet-curable resin having a tensile strength of 35 to 65 MPa obtained by curing an ultraviolet-curable resin each containing the same oligomer, and wherein the inner collective coating layer is substantially adjacent to the optical fiber strand. Are arranged only in a gap defined by the outer peripheral surface of the first member and the common tangent line thereof.

Further, in the method for manufacturing an optical fiber ribbon according to the present invention, a plurality of optical fiber wires arranged in parallel with each other are covered with an inner collective coating layer made of a first ultraviolet curable resin and integrated. A first step of obtaining a multi-core unit, and a second step of coating the outer peripheral surface of the multi-core unit with an outer batch coating layer made of a second ultraviolet curable resin,
In the method for producing an optical fiber ribbon, a tensile strength of 35 to 65 MPa obtained by curing an ultraviolet-curable resin containing the same oligomer as the first ultraviolet-curable resin and the second ultraviolet-curable resin, respectively.
Using an ultraviolet curable resin, and the inner batch coating layer,
Substantially, it is characterized in that the optical fiber is disposed only in a gap defined by the outer peripheral surfaces of the optical fiber wires adjacent to each other and their common tangent line.

According to the present invention, as a material of the inner collective coating layer and the outer collective coating layer of the optical fiber ribbon, a tensile strength of 35 to 65 MPa obtained by curing an ultraviolet curable resin containing the same oligomer, respectively. By using the ultraviolet curable resin, the compatibility between the inner collective coating layer and the outer collective coating layer is improved, so that the adhesion of the resin constituting these layers is improved without imparting excessive tackiness. be able to. In addition, when the collective coating layer is formed on the conventional optical fiber ribbon, there is a problem that the resin hardly hardens around the adjacent portions of the optical fiber wires adjacent to each other. By arranging the layers substantially only in the gaps formed by the outer peripheral surfaces of the optical fiber strands adjacent to each other and their common tangents, the inner batch coating layer is also formed around the adjacent parts of the optical fiber strands. Can be formed efficiently and reliably. Further, by coating the multi-core unit integrated with the inner collective coating layer with the outer coating layer having a predetermined tensile strength, a sufficiently high strength is provided. Therefore, with the optical fiber tape of the present invention, it is possible to sufficiently prevent an increase in transmission loss under water or in a humid environment while maintaining sufficiently high single-fiber separation and sufficiently high strength. Become. Moreover,
The optical fiber ribbon of the present invention having such excellent characteristics can be efficiently and reliably obtained by the manufacturing method of the present invention.

[0016] The term "tensile strength" used herein means JIS.
It refers to "tensile fracture strength" measured according to the method specified in K7127. That is, the tensile strength according to the present invention is a thickness of about 200 μm using an ultraviolet curable resin.
JIS No. 2 dumbbell-type test piece was prepared, and the tensile speed was 5
A value [MPa] calculated by pulling a test piece at 0 mm / min and dividing a load value obtained when the test piece breaks by a cross-sectional area of the test piece.

In the present invention, it is preferable that the first ultraviolet-curable resin is obtained by curing the resin composition in an atmosphere having an oxygen concentration of 1 to 10% by volume.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
In the drawings, the same or corresponding portions are denoted by the same reference characters.

The optical fiber ribbon of the present invention comprises a plurality of optical fiber strands arranged in parallel with each other and coated with an inner batch covering layer made of a first ultraviolet curable resin to be integrated into a multicore unit. In an optical fiber ribbon obtained by covering the outer peripheral surface of the multi-core unit with an outer batch covering layer made of a second ultraviolet-curable resin, the first ultraviolet-curable resin and the second ultraviolet-curable resin are respectively An ultraviolet curable resin having a tensile strength of 35 to 65 MPa obtained by curing an ultraviolet curable resin containing the same oligomer, and wherein the inner collective coating layer is substantially the outer periphery of the optical fiber strand adjacent to each other; It is characterized by being arranged only in the gap formed by the surfaces and their common tangent lines, and maintains a sufficiently high single-core separation and a sufficiently high strength. Reluctant, and makes it possible to sufficiently prevent an increase in transmission loss under water or humid environment.

FIG. 1 is a schematic sectional view showing a preferred embodiment of the optical fiber ribbon of the present invention. In FIG. 1, an optical fiber ribbon 1 includes four optical fiber wires 2a to 2d arranged in parallel with each other. Two adjacent ones of the optical fiber strands 2a to 2d are in contact with each other, and are substantially arranged only in the gap defined by the outer peripheral surface thereof and the common tangent line. The multi-core unit 4 is formed integrally by the inner collective coating layers 3a to 3f. Further, the outer peripheral surface of the multi-core unit 4 is covered with an outer collective covering layer 5 made of a second ultraviolet curable resin.

Here, the first UV-curable resin forming the inner collective coating layers 3a to 3f and the second UV-curable resin forming the outer collective coating layer 5 are each a UV-curable resin containing the same oligomer. , And their tensile strength must be in the range of 35 to 65 MPa. When the first UV-curable resin and the second UV-curable resin are each obtained by curing an ultraviolet-curable resin not containing the same oligomer, the inner collective coating layer and the outer collective coating layer The adhesive strength between them is reduced, and it is not possible to sufficiently prevent an increase in transmission loss under water or in a humid environment. Further, the tensile strength of either one of the first ultraviolet resin and the second ultraviolet curing resin is 65 MPa.
Exceeds 30MPa, the single core separation becomes insufficient, while 35MP
If it is less than a, the strength of the optical fiber ribbon becomes insufficient, and the optical fiber becomes liable to be damaged even by a small distortion at the time of manufacturing a cable or after laying.

The first UV-curable resin according to the present invention is preferably obtained by curing the above-mentioned UV-curable resin in an atmosphere having an oxygen concentration of 1 to 10% by volume. If the oxygen concentration in the atmosphere at the time of curing the resin composition is less than 1% by volume, the curing of the ultraviolet curable resin tends to proceed excessively, and as a result, the adhesive strength of the obtained first ultraviolet curable resin And the strength tends to be insufficient such that the adhesion between the inner collective coating layer and the outer collective coating layer decreases and peeling occurs. In addition, when an acrylic resin is used as the ultraviolet curable resin, anaerobic polymerization tends to occur when curing is performed in such an atmosphere having a low oxygen concentration, and as a result, die clogging easily occurs in a coating apparatus or the like. Become. On the other hand, if the oxygen concentration is 10
When the content exceeds the capacity%, curing becomes insufficient over the inside and outside of the resin, and the adhesive strength between the optical fiber and the inner collective coating layer tends to decrease.

Further, the first ultraviolet curable resin and the second ultraviolet curable resin according to the present invention each preferably have a Young's modulus of 600 to 1000 MPa. If the Young's modulus of any one of the first UV-curable resin and the second UV-curable resin is less than 400 MPa, the optical fiber is broken when subjected to an external force such as lateral pressure and transmitted. Loss tends to increase easily, and particularly, when the Young's modulus of the second ultraviolet curable resin is 40
If it is less than 0 MPa, the surface of the tape core tends to be sticky. On the other hand, the UV-curable resin has a Young's modulus of 1
If it exceeds 000 MPa, the shrinkage stress at the time of curing the resin increases, and the optical fiber becomes liable to be broken, and as a result, the transmission loss tends to increase. In addition, the Young's modulus mentioned here means "tensile secant modulus" measured in accordance with the method specified in JIS K 7127. That is, the Young's modulus according to the present invention means that a JIS No. 2 dumbbell-type test piece having a thickness of about 200 μm is prepared using an ultraviolet curable resin, and the test piece is pulled at a pulling speed of 1 mm / min to generate 2.5% strain. Means the value [MPa] calculated by dividing the load value required for the above by the cross-sectional area of the test piece.

In the present invention, the oligomer commonly contained in the ultraviolet curable resin used as the material of the first ultraviolet curable resin and the second ultraviolet curable resin is a main component of the ultraviolet curable resin. Usually, a polymer compound having a reactive group (such as a hydrocarbon group having a carbon-carbon double bond) at both ends of a molecular chain is used. Here, the oligomer used in the present invention is not particularly limited as long as the obtained ultraviolet curable resin satisfies the above conditions, but when a urethane acrylate oligomer is used,
This is preferable because the effect of preventing transmission loss increase under water or in a humid environment can be further improved, and strength and single fiber separation can be achieved at a higher level. Specific examples of such an oligomer include the following oligomers A and B:
Oligomer A: Polytetramethylene glycol (PTM
G), copolymer of tolylene diisocyanate (TDI) and hydroxyethyl acrylate (HEA) oligomer B: copolymer of polypropylene glycol (PPG), tolylene diisocyanate (TDI) and hydroxyethyl acrylate (HEA), etc. .

The UV-curable resin used in the present invention generally contains a diluent monomer and a photoinitiator in addition to the oligomer (preferably a urethane acrylate oligomer). As the diluent monomer, specifically, N-vinylpyrrolidone, ethylene oxide-modified bisphenol A diacrylate, isobornyl acrylate, phenoxyethyl acrylate, and a mixture of two or more of these can be used. Further, as the photoinitiator, a conventionally known photoinitiator such as Irgacure 184 (manufactured by Ciba Specialty Chemicals) can be used. Furthermore, in the present invention, it is particularly preferable to use, as the material of the first UV-curable resin and the second UV-curable resin, resin compositions in which the types and amounts of the above-mentioned components are the same.

The thickness of the outer batch coating layer according to the present invention is:
It is preferably 15 to 70 μm, more preferably 15 to 70 μm.
To 40 μm, and more preferably 20 to 35 μm. If the thickness of the outer batch coating layer is less than the lower limit, the strength tends to be insufficient such that the glass fiber of the optical fiber becomes liable to be damaged even with a slight side pressure. On the other hand, when the thickness of the outer batch coating layer exceeds the upper limit, the layer is less likely to be divided, and the single-core separation property tends to decrease.

The optical fiber used in the present invention is not particularly limited, and a conventionally known optical fiber can be used. Usually, a glass fiber is coated with a resin coating layer, What was covered with the coloring layer which consists of is used. In the present invention, the adhesive force between the optical fiber and the inner collective coating layer is preferably 0.1 to 10 g / cm, more preferably 0.1 to 10 g / cm.
-5 g / cm, more preferably 0.5-1.5 g / cm.
g / cm. When the adhesive force between the optical fiber and the inner collective coating layer is less than the lower limit, a blister (water droplet) is formed between the optical fiber and the inner collective coat layer when used in water or in a humid environment. ) Occurs and transmission loss tends to increase. On the other hand, if the adhesive force between the optical fiber and the inner batch coating layer exceeds the upper limit, the single-fiber separation property tends to decrease. In addition, the adhesion here means
Value [g / cm] measured in a 180 degree peel test
Say.

The optical fiber ribbon of the present invention having such a structure has a sufficiently high strength, and not only is the optical fiber tape hardly damaged at the time of manufacture and at the time of work after laying, but also Even when used underwater or in a humid environment, the transmission loss can be sufficiently prevented. Further, the optical fiber ribbon of the present invention has a sufficiently high single-fiber separation property, such as an operation of separating the outer collective coating layer 5 and separating the optical fiber strand 2a from the optical fiber ribbon 1. Can be performed easily and reliably.

Although FIG. 1 shows a four-core type optical fiber ribbon having four optical fiber strands, the number of optical fiber strands provided in the optical fiber ribbon of the present invention is particularly limited. However, it may be a two-core type, a six-core type, an eight-core type, or the like.

Next, a method for manufacturing the optical fiber ribbon of the present invention will be described.

According to the manufacturing method of the present invention, a plurality of optical fibers arranged in parallel with each other are covered with an inner batch covering layer made of a first ultraviolet curable resin and integrated to obtain a multi-core unit. And a second step of coating the outer peripheral surface of the multi-core unit with an outer batch coating layer made of a second ultraviolet-curable resin, the method of manufacturing an optical fiber ribbon, the method comprising: A UV curable resin having a tensile strength of 35 to 65 MPa obtained by curing a UV curable resin containing the same oligomer as the curable resin and the second UV curable resin, respectively, and substantially forming the inner batch coating layer. In addition, the optical fiber is arranged only in a gap defined by the outer peripheral surfaces of the optical fiber wires adjacent to each other and their common tangent line. The manufacturing method of the present invention having such a configuration can be suitably implemented using a manufacturing apparatus described later.

FIG. 2 is a schematic diagram showing an example of a manufacturing apparatus used in the method of manufacturing an optical fiber ribbon according to the present invention. In the apparatus shown in FIG. 2, first, the optical fiber unreeling supply 201 is connected to the concentrator 20.
5 and a plurality of optical fiber wires 2 to the coating device 206.
Is transported. Here, the supply 201 applies tension (usually about several tens g) to a plurality of rotatable reels 202 for sending out the wound optical fiber 2 and the optical fiber 2 transferred from each reel 202. A dancer roller 203 for imparting and preventing deflection, a guide roller 204 having grooves corresponding to the number of the reels 202, and arranging a plurality of optical fiber wires in parallel at a fixed interval, and fixing the transport direction thereof. It has. The plurality of optical fiber strands 2 conveyed in this manner are connected to a concentrator 2
05 and the coating device 206 are arranged in parallel with each other in a direction perpendicular to the paper surface.

The pressurized tank 2 connected to the coating device 206
An ultraviolet curable resin containing an oligomer is contained in 07, and the ultraviolet curable resin is supplied from the pressurized tank 207 to the coating device 206 and applied to the optical fiber 2. Further, the ultraviolet ray irradiating device 208 irradiates ultraviolet rays to the optical fiber 2 after the application of the ultraviolet curable resin to cure the ultraviolet curable resin, thereby obtaining the first ultraviolet curable resin (tensile strength: 35 to 65 MPa). A multi-core unit comprising a plurality of optical fiber wires formed substantially only in the gap formed by the outer peripheral surfaces of the optical fiber wires adjacent to each other and their common tangent line 4 is obtained. Here, the ultraviolet irradiation device 2
The above-mentioned hardening treatment in 09 is preferably performed in an atmosphere having an oxygen concentration of 1 to 10% by volume. If the oxygen concentration in the atmosphere is less than 1% by volume, the curing reaction tends to proceed excessively, and as a result, the strength tends to be insufficient such that the adhesive strength on the surface of the inner batch coating layer decreases and peeling occurs. is there.
In addition, when an acrylic resin such as a urethane acrylate resin is used as the ultraviolet curable resin, anaerobic polymerization is likely to occur, and as a result, the resin is cured even by a slight irradiation of ultraviolet light, and the die is clogged at the exit of the apparatus. Will happen. On the other hand, when the oxygen concentration in the atmosphere increases, the adhesive force on the surface of the inner batch coating layer tends to be improved. There is a tendency that it becomes difficult to obtain desired characteristics due to insufficient adhesive force.

In the present invention, the coating device 206
And an ultraviolet irradiation device 208 by a connection box 209 to form an airtight structure, and it is preferable to replace the inside thereof with a mixed gas of an inert gas such as a nitrogen gas and an oxygen gas having the above concentration. If the connection box 209 is used to form an airtight structure between the coating device 206 and the ultraviolet irradiation device 208, the control of the oxygen concentration of the atmosphere in the resin curing step tends to be simple and easy. The coating device 206 and the connection box 2
09 and the connection box 209 and the ultraviolet irradiation device 2
An elastic body such as rubber can be used for the connection portion with the 08. If necessary, a connection port for introducing the mixed gas into the connection box 209 or an exhaust port for discharging the mixed gas may be provided.

Next, an ultraviolet curable resin containing the same oligomer as that used for the material of the first ultraviolet curable resin is supplied from a tank 207 'to a coating device 206', and the ultraviolet curable resin is applied to the coating device 206 '. The ultraviolet curable resin is applied to the multi-core unit 4. Then, in the ultraviolet ray irradiating device 208 ′, the outer batch coating layer made of the second ultraviolet curable resin (tensile strength: 35 to 65 MPa) is formed by curing the ultraviolet curable resin, and the optical fiber ribbon 1 of the present invention is formed. can get. Here, the conditions for producing the outer coating resin are not particularly limited, but the oxygen concentration of the atmosphere in the ultraviolet irradiation device 208 ′ is 1 to 10% by volume.
It is preferable that

The optical fiber ribbon obtained in this manner is supplied to the guide roller 210 and the delivery capstan 2.
11. The film is wound on a reel 215 by a winding device 213 via a winding tension dancer 212. Reel 21
The tension of the optical fiber ribbon 1 wound around 5 can be set to a desired value by the winding tension dancer 212, but is usually several tens to several hundreds g.

[0037]

EXAMPLES The present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples. (Ultraviolet curable resin) In the following examples and comparative examples, optical fiber tape cores were produced using ultraviolet curable resins A and B having the following compositions, respectively.

UV curable resin A oligomer: polytetramethylene glycol (PTM
G), copolymer of tolylene diisocyanate (TDI) and hydroxyethyl acrylate (HEA) Diluent monomer: mixture of N-vinylpyrrolidone and ethylene oxide-modified bisphenol A diacrylate Photoinitiator: Irgacure 184 (manufactured by Ciba Specialty Chemicals) ).

UV curable resin B oligomer: copolymer of polypropylene glycol (PPG), tolylene diisocyanate (TDI) and hydroxyethyl acrylate (HEA) Diluent monomer: mixture of isobornyl acrylate and phenoxyethyl acrylate Photoinitiator: Irgacure 184 (manufactured by Ciba Specialty Chemicals).

Example 1 Using the apparatus shown in FIG. 2, the procedure shown in FIG.
An optical fiber ribbon having the structure shown in FIG.

The outer diameter of the optical fiber is 125 μm.
Single-mode optical fiber bare glass is double-coated with a layer made of urethane acrylate ultraviolet curing resin,
Further, a coating (outer diameter: 250 μm) covered with a colored layer made of an ultraviolet curable resin was used. Four of the optical fiber strands were wound around four reels of an optical fiber unreeling supply, and were sequentially transferred to a concentrator and a coating apparatus.

(Formation of Inner Collective Coating Layer) Next, the above-mentioned ultraviolet curable resin A is applied to these optical fiber wires in a coating device, and further in an ultraviolet irradiation device in an atmosphere having an oxygen concentration of 0% by volume. The ultraviolet curable resin A was cured to form an inner collective coating layer only in the gaps formed by the outer peripheral surfaces of adjacent optical fiber wires and their common tangent lines, thereby forming a 4-core unit.

(Formation of Outer Collective Coating Layer) Further, an ultraviolet curable resin A is applied on the outer peripheral surface of the four-core unit and cured to form an outer collective coating layer. A core wire (thickness: 300 μm) was obtained. The thus obtained optical fiber ribbon was wound on a reel of a winding device with a winding tension of 150 g.

Example 2 In the step of forming the inner batch coating layer, the oxygen concentration was 1% by volume.
An optical fiber ribbon having the structure shown in FIG. 1 was obtained in the same manner as in Example 1 except that the ultraviolet-curable resin A was cured in the atmosphere described above.

Example 3 The structure shown in FIG. 1 was changed in the same manner as in Example 1 except that the ultraviolet curable resin A was cured in an atmosphere having an oxygen concentration of 10% by volume in the step of forming the inner batch coating layer. The obtained optical fiber ribbon was obtained.

Example 4 In the step of forming the inner batch coating layer, the oxygen concentration was 8% by volume.
An optical fiber ribbon having the structure shown in FIG. 1 was obtained in the same manner as in Example 1 except that the ultraviolet-curable resin A was cured in the atmosphere described above.

Comparative Example 1 Four optical fiber strands similar to those in Example 1 were arranged in parallel with each other, and an ultraviolet curable resin A was applied. Next, these optical fiber wires are irradiated with ultraviolet rays in an atmosphere having an oxygen concentration of 0% by volume to cure the ultraviolet curable resin A to form a coating layer, which has a structure shown in FIG. An optical fiber ribbon was obtained.

COMPARATIVE EXAMPLE 2 Four optical fiber wires similar to those in Example 1 were arranged in parallel with each other, and an ultraviolet curable resin A was applied. Next, these optical fiber strands are irradiated with ultraviolet rays in an atmosphere having an oxygen concentration of 0% by volume to cure the ultraviolet curable resin A, and are constituted by the outer peripheral surfaces of adjacent optical fiber strands and their common tangents. A coating layer was formed only on the voids to be formed to obtain an optical fiber ribbon having the structure shown in FIG.

Comparative Example 3 In the step of forming the outer batch coating layer, the ultraviolet curable resin B was used.
An optical fiber ribbon having the structure shown in FIG. 1 was obtained in the same manner as in Example 2 except for using.

Comparative Example 4 In the step of forming the inner batch coating layer, the oxygen concentration was 0% by volume.
An optical fiber ribbon having the structure shown in FIG. 1 was obtained in the same manner as in Example 1 except that the ultraviolet-curable resin A was cured in the atmosphere described above.

For each of Examples 1 to 4 and Comparative Examples 1 to 4 thus obtained, the materials of the inner collective coating layer (collective coat layers in Comparative Examples 1 and 2) and the outer collective coat layer Table 1 shows the tensile strength, the oxygen concentration when the resin of the inner batch coating layer is cured, and the tensile strength. In the column of the material of each layer in the table, “A” means the above-mentioned ultraviolet-curable resin A, and “B” means the above-mentioned ultraviolet-curable resin B.

[0052]

[Table 1]

Next, the following tests were performed on the optical fiber ribbons of Examples 1 to 4 and Comparative Examples 1 to 4.

(Hot Water Characteristics Evaluation Test) 1000 m of each optical fiber tape core was wound into a coil to form a bundle having a diameter of 300 mm, which was kept immersed in 60 ° C. hot water for 14 days. Thereafter, the transmission loss of the four optical fibers of each optical fiber tape was measured using an optical pulse tester (OTDR, manufactured by Ando Electric, wavelength: 1.55 μm). Table 2 shows the results of the four optical fiber strands of each optical fiber tape with the largest transmission loss.

(Evaluation Test for Single-Core Separability) The subject manually cuts each optical fiber tape having a length of 1 m and separates it into a single-core optical fiber. The properties were evaluated. Table 2 shows the results.

(Side Pressure Characteristic Evaluation Test) The transmission loss after winding each optical fiber tape core wire with a tension of 300 g on a bobbin having a body diameter of about 300 mm with sandpaper # 240 adhered to the body surface was measured. The measurement was performed using a pulse tester (OTDR, manufactured by Ando Electric, wavelength: 1.55 μm). Table 2 shows the results of the four optical fiber strands of each optical fiber tape with the largest transmission loss.

(Twisting characteristic evaluation test) After stretching 100 mm of the optical fiber ribbon with 300 g of tension and twisting one end 10 or 20 times, damage such as cracking in the optical fiber ribbon and peeling of the coating layer was observed. Was observed under a microscope.
Table 2 shows the results.

[0058]

[Table 2]

As shown in Table 2, it was confirmed that the optical fiber ribbons of Examples 1 to 4 were sufficiently prevented from increasing transmission loss even when used in warm water. Each of these optical fiber ribbons had a sufficiently high strength and a sufficiently high single-core separation property.

On the other hand, in the optical fiber ribbon of Comparative Example 1, when used in warm water, blisters occurred and transmission loss increased. In addition, the optical fiber ribbons of Comparative Examples 2 and 4 were inferior in single-core separation, and in addition,
The strength was also insufficient such that peeling was observed between the inner collective coating layer and the outer collective coating layer after the 0 th twist. Furthermore, the optical fiber ribbon of Comparative Example 3 was insufficient in strength, such as a remarkable increase in transmission loss in the lateral pressure characteristic evaluation test, and damage after ten twists in the twist characteristic evaluation test. Was.

[0061]

As described above, according to the present invention, a sufficiently high single-core separation property and a sufficiently high strength are obtained.
Even when used underwater or in a humid atmosphere, it is possible to obtain an optical fiber ribbon in which an increase in transmission loss is sufficiently prevented. Further, according to the manufacturing method of the present invention, it becomes possible to efficiently and reliably obtain the optical fiber ribbon of the present invention having the above excellent characteristics.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a preferred embodiment of an optical fiber ribbon according to the present invention.

FIG. 2 is a schematic configuration diagram illustrating an example of a manufacturing apparatus used in the method of manufacturing an optical fiber ribbon according to the present invention.

FIGS. 3A and 3B are schematic cross-sectional views showing examples of a conventional optical fiber ribbon. FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical fiber tape core wire, 2, 2a-2d ... Optical fiber wire, 3a-3f ... Inner collective covering layer, 4 ... Multi-core unit, 5 ... Outer collective covering layer, 6, 6a-6f ... Collective covering layer , 201 ... Optical fiber feeding supply, 202,
215: reel, 203, 212: dancer roller, 2
04, 210, 214: guide roller, 205: line concentrator, 206, 206 ': coating device, 207, 207'
... pressurized tank, 208, 208 '... ultraviolet irradiation device,
209: connection box, 211: capstan, 213: winding device.

Continued on the front page F term (reference) 2H001 BB19 DD23 DD35 KK17 KK22 MM01 2H050 BA01 BA18 BB33Q BB33S BC03 BD05 4G060 AA01 AA03 AC12 AC15 AD22 AD43 AD51 CB09 CB22

Claims (4)

[Claims] 1. A multi-core unit in which a plurality of optical fiber wires arranged in parallel with each other are covered with an inner collective coating layer made of a first ultraviolet curable resin to be integrated into a multi-core unit, and an outer peripheral surface of the multi-core unit Is coated with an outer batch coating layer made of a second ultraviolet curable resin, wherein the first ultraviolet curable resin and the second ultraviolet curable resin each contain the same oligomer. Tensile strength 35-65MPa obtained by curing conductive resin
UV curable resin, and the inner batch coating layer,
An optical fiber ribbon, wherein the optical fiber ribbon is arranged substantially only in a gap formed by the outer peripheral surfaces of the optical fiber strands adjacent to each other and their common tangent. 2. The light according to claim 1, wherein the first UV-curable resin is obtained by curing the resin composition in an atmosphere having an oxygen concentration of 1 to 10% by volume. Fiber tape core. 3. A first step of coating a plurality of optical fiber wires arranged in parallel with each other with an inner collective coating layer made of a first ultraviolet curable resin and integrating them to obtain a multi-core unit; A second step of coating the outer peripheral surface of the multi-core unit with an outer batch coating layer made of a second ultraviolet-curable resin, the method comprising the steps of: Tensile strength of 35 to 65 M obtained by curing an ultraviolet-curable resin containing the same oligomer as the second ultraviolet-curable resin
Using an ultraviolet curable resin of Pa, and wherein the inner batch coating layer is disposed substantially only in the gap formed by the outer peripheral surfaces of the optical fiber strands adjacent to each other and their common tangent line. Of manufacturing optical fiber ribbon. 4. In the first step, the resin composition is cured in an atmosphere having an oxygen concentration of 1 to 10% by volume to obtain the first ultraviolet-curable resin.
A method for manufacturing the optical fiber ribbon according to claim 3.