Separable optical fiber ribbon and method for manufacturing separable optical fiber ribbon

Abstract

To provide a split type coated optical fiber ribbon having both of splittability and single core separability.SOLUTION: A separable optical fiber ribbon according to the present invention includes a plurality of optical fiber colored core wires arranged in parallel, a tape layer covering the plurality of optical fiber colored core wires and connecting the plurality of optical fiber colored core wires to form a collective optical fiber ribbon, and a plurality of optical fiber ribbons covering the plurality of collective optical fiber ribbons arranged in parallel. A binding layer connecting the plurality of ribbon-type optical fibers to form a split-type optical-fiber ribbon, wherein a ribbon layer including the tape layer and the binding layer has a first glass-transition temperature and a second glass-transition temperature which are different from each other, and a balanced modulus of the ribbon layer is 44. 7MPa or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a splittable optical fiber ribbon and a method for manufacturing the splittable optical fiber ribbon. [Background technology]

[0002] A technique for forming an integrated optical fiber ribbon by connecting multiple colored optical fiber core wires to each other using a tape layer formed with an ultraviolet-curable resin is known (Patent Document 1). Another technique for forming a separable optical fiber ribbon by further connecting multiple integrated optical fiber ribbon core wires with a band layer formed with an ultraviolet-curable resin is known (Patent Document 2). A separable optical fiber ribbon core wire is required to have the property of being able to be separated into integrated optical fiber ribbon core wires by removing only the outermost binding layer (hereinafter referred to as "separability"). Additionally, a separable optical fiber ribbon core wire is required to have the property of being able to separate the colored optical fiber core wires one by one from the integrated optical fiber ribbon core wire by peeling off the tape layer and colored layer (hereinafter referred to as "single fiber separability"). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Application No. 116658 / 1983 [Patent Document 2] Patent No. 2551622 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to maintain the divisibility of a splittable optical fiber ribbon, the elastic modulus of the tape layer must be high and the elastic modulus of the bind layer must be low. On the other hand, in order to maintain the single fiber separation property, the ribbon layer consisting of the tape layer and the bind layer must have a high breaking elongation. However, it is very difficult to increase both the elastic modulus and the breaking elongation, and it has been difficult to satisfy both the divisibility and the single fiber separation property.

[0005] In view of the above-mentioned problems, the present invention has an object to provide a splittable optical fiber ribbon that is both easily splittable and easily separable into individual fibers, and a method for manufacturing the splittable optical fiber ribbon. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided a splittable optical fiber ribbon core wire comprising: a plurality of colored optical fiber core wires arranged in parallel; a tape layer that covers the plurality of colored optical fiber core wires and connects the plurality of colored optical fiber core wires to form an integrated optical fiber tape core wire; and a binding layer that covers the plurality of integrated optical fiber tape core wires arranged in parallel and connects the plurality of integrated optical fiber tape core wires to form a splittable optical fiber ribbon core wire, wherein the ribbon layer consisting of the tape layer and the binding layer has a first glass transition temperature and a second glass transition temperature that are different from each other, and the equilibrium elastic modulus of the ribbon layer is 44.7 MPa or less.

[0007] According to another aspect of the present invention, there is provided a method for manufacturing a splittable optical fiber ribbon, comprising the steps of: arranging a plurality of colored optical fiber core wires in parallel; forming a tape layer that covers the plurality of colored optical fiber core wires and connects the plurality of colored optical fiber core wires to form an integrated optical fiber ribbon core wire; and forming a bind layer that covers the plurality of parallel-arranged integrated optical fiber ribbon core wires and connects the plurality of integrated optical fiber ribbon core wires to form a splittable optical fiber ribbon core wire, wherein a ribbon layer consisting of the tape layer and the bind layer has a first glass transition temperature and a second glass transition temperature that are different from each other, and the equilibrium elastic modulus of the ribbon layer is 44.7 MPa or less. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a splittable optical fiber ribbon that is both splittable and easy to separate into individual fibers, and a method for manufacturing the same. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view of a splittable optical fiber ribbon according to an embodiment. [Figure 2] 1 is a cross-sectional view of an integrated optical fiber ribbon according to an embodiment. [Figure 3] 1 is a cross-sectional view of a colored optical fiber core wire in one embodiment. [Figure 4] FIG. 10 is a cross-sectional view showing an example of a sample piece of a ribbon layer in one embodiment. [Figure 5] 1 is a diagram showing the relationship between temperature, storage modulus, loss tangent value, and glass transition temperature in a ribbon layer of a splittable optical fiber ribbon according to an embodiment. [Figure 6] 1A and 1B are diagrams illustrating division and separation of a splittable optical fiber ribbon according to an embodiment of the present invention. [Figure 7A] 3 is an example of a division pattern of a splittable optical fiber ribbon according to an embodiment. [Figure 7B] 3 is an example of a division pattern of a splittable optical fiber ribbon according to an embodiment. [Figure 7C] 3 is an example of a division pattern of a splittable optical fiber ribbon according to an embodiment. [Figure 7D] 3 is an example of a division pattern of a splittable optical fiber ribbon according to an embodiment. [Figure 7E] 3 is an example of a division pattern of a splittable optical fiber ribbon according to an embodiment. [Figure 7F] 3 is an example of a division pattern of a splittable optical fiber ribbon according to an embodiment. [Figure 8] 1 is a schematic diagram of a manufacturing apparatus for a splittable optical fiber ribbon according to an embodiment. [Figure 9] FIG. 2 is a block diagram of a control device according to an embodiment. [Figure 10] 1 is a flowchart of a method for manufacturing a splittable optical fiber ribbon according to an embodiment. [Figure 11]1 is a flowchart of a method for manufacturing a tape layer in one embodiment. [Figure 12] 1 is a flowchart of a method for manufacturing a bind layer in one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described with reference to the accompanying drawings. The same reference numerals throughout the specification refer to substantially the same components.

[0011] 1 is a cross-sectional view of a separable optical fiber ribbon 1 according to this embodiment. The separable optical fiber ribbon 1 includes two bundled optical fiber tape conductors 2. The bundled optical fiber tape conductor 2 includes two colored optical fiber tape conductors 3. The two bundled optical fiber tape conductors 2 are each bundled in a belt shape via a binding layer 11. Note that the number of fibers in the separable optical fiber ribbon conductor 1 is four in this embodiment, but is not limited to this and may be, for example, eight, twelve, twenty-four, etc.

[0012] The binding layer 11 is the outermost layer of the separable optical fiber ribbon 1. The binding layer 11 covers the plurality of bundled optical fiber tape core wires 2 arranged in parallel, and connects the plurality of bundled optical fiber tape core wires 2 to form the separable optical fiber ribbon 1. The binding layer 11 has the function of bundling the plurality of bundled optical fiber tape core wires 2 and protecting the plurality of bundled optical fiber tape core wires 2 from external forces. The binding layer 11 is formed by curing an ultraviolet-curable resin by irradiating it with ultraviolet rays. In a cross-sectional view, the binding layer 11 is formed in a substantially oval shape around the outer periphery of the two bundled optical fiber tape core wires 2.

[0013] 2 is a cross-sectional view of an integrated optical fiber ribbon 2 according to this embodiment. Each integrated optical fiber ribbon 2 includes two colored optical fiber ribbons 3. The colored optical fiber ribbons 3 are bundled in pairs in a belt shape via a ribbon layer 21. The number of colored optical fiber ribbons 3 is not limited to this, and may be, for example, four, eight, or twelve.

[0014] The tape layer 21 is the outermost layer of the bundled optical fiber ribbon 2. The tape layer 21 covers the plurality of colored optical fiber core wires 3 arranged in parallel and connects the plurality of colored optical fiber core wires 3 to form the bundled optical fiber ribbon 2. The tape layer 21 has the function of bundling the plurality of colored optical fiber core wires 3 and protecting the plurality of colored optical fiber core wires 3 from external forces. The tape layer 21 is formed by curing an ultraviolet-curable resin by irradiating it with ultraviolet rays. In a cross-sectional view, the tape layer 21 is formed in a substantially oval shape around the outer periphery of the two colored optical fiber core wires 3.

[0015] 3 is a cross-sectional view of a colored optical fiber 3 in this embodiment. The colored optical fiber 3 includes a bare optical fiber 31, a primary layer 32, a secondary layer 33, and a colored layer 34. The bare optical fiber 31 is formed of, for example, silica-based glass. The primary layer 32 is formed of an ultraviolet-curable resin and is coated on the outer periphery of the bare optical fiber 31. The secondary layer 33 is formed of an ultraviolet-curable resin and is coated on the outer periphery of the primary layer 32. The primary layer 32 and the secondary layer 33 are each formed by curing the ultraviolet-curable resin by irradiation with ultraviolet light. The bare optical fiber 31, the primary layer 32, and the secondary layer 33 are collectively referred to as the "optical fiber."

[0016] The colored layer 34 is the outermost layer of the colored optical fiber core 3. The colored layer 34 has the function of protecting the bare optical fiber 31, the primary layer 32, and the secondary layer 33 from external forces. The colored layer 34 is formed of an ultraviolet-curable resin and covers the outer periphery of the secondary layer 33. Like the primary layer 32 and the secondary layer 33, the colored layer 34 is formed by curing the ultraviolet-curable resin by irradiating it with ultraviolet rays. The ultraviolet-curable resin that forms the colored layer 34 is an oligomer, a monomer, or the like, and may contain additives such as a photoinitiator, a photosensitizer, an ultraviolet absorber, an antioxidant, a chain transfer agent, a lubricant such as silicone, and titanium oxide.

[0017] The colored layer 34 is colored with a colorant mixed with a pigment or a lubricant so that the multiple colored optical fiber cores 3 can be distinguished from one another. The colors may be, for example, white, black, gray, purple, blue, light blue, green, brown, yellow, orange, pink, red, etc. The colored layer 34 may be a secondary layer 33 colored with a colorant. In this case, the secondary layer 33 can be colored by adding a colorant similar to the colorant used to color the ultraviolet-curable resin used in the colored layer 34 to the ultraviolet-curable resin used in the secondary layer 33.

[0018] In this embodiment, the primary layer 32, the secondary layer 33, the colored layer 34, the tape layer 21, and the bind layer 11 are formed of an ultraviolet-curable resin. The ultraviolet-curable resin is, for example, a urethane acrylate (methacrylate)-based ultraviolet-curable resin. The urethane acrylate (methacrylate)-based ultraviolet-curable resin is composed of an oligomer, a monomer, and the like. The ultraviolet-curable resin composition appropriately contains additives such as a photoinitiator, a photosensitizer, a chain transfer agent, an ultraviolet absorber, an antioxidant, a silane coupling agent, a lubricant such as silicone, and a pigment such as titanium oxide. By appropriately adjusting the components of the ultraviolet-curable resin composition, physical properties such as the conversion rate, Young's modulus, and elongation at break can be controlled.

[0019] Examples of the photoinitiator include 1-hydroxycyclohexyl-phenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,4,6-trimethylbenzoyl bis(p-tolyl)phosphine oxide, ethyl (2,4,6-trimethylbenzoyl)(phenyl)phosphinate, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide. oxide), 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, etc. The type of photoinitiator is not limited to those mentioned above.

[0020] The addition of photoinitiators and photosensitizers enables efficient UV curing using UV-LEDs. Examples of photoinitiators with absorption at wavelengths above 300 nm include 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,4,6-trimethylbenzoyl bis(p-tolyl)phosphine oxide, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide. Examples of photosensitizers with absorption at wavelengths above 300 nm include 2,4-diethyl-9H-thioxanthen-9-one and 2-isopropylthioxanthone.

[0021] Furthermore, an additive (photoacid generator) that generates acid when irradiated with ultraviolet light may be added as appropriate to promote the reaction between the silane coupling agent and the bare optical fiber 31. An example of the photoacid generator is CPI-200K manufactured by San-Apro Co., Ltd. However, the type of photoacid generator is not limited to this.

[0022] A mercapto-containing compound may be added to adjust the Young's modulus of the UV-curable resin. The mercapto-containing compound has the effect of terminating the polymerization of the polymerizable compound, such as urethane (meth)acrylate, contained in the UV-curable resin, by reacting with the mercapto group. Examples of the mercapto-containing compound include isooctyl 3-mercaptopropionate and ethyl mercaptan. Mercaptan, 1-Butanethiol, 1-Heptanethiol, 1-Undecanethiol, 4-Hydroxybenzenethiol, (2-Mercaptoethyl)pyrazine, 2,3-Butanedithiol, 3-Methyl-2-butanethiol, 3-Mercapto-1,2,4-triazole, 1,3,4-Thiadiazole-2-thiol, and Isobutyl Mercaptan. Examples of mercaptan-containing compounds include 4-methoxy-α-toluenethiol, 4,4'-biphenyldithiol, trimethylsilylmethanethiol, 1,4-butanedithiol, 1,8-octanedithiol, 3-ethoxybenzenethiol, and pentaerythritol tetra(3-mercaptopropionate). The types of mercapto-containing compounds are not limited to these. Furthermore, the mercapto-containing compounds are not limited to mercapto-containing compounds. Compounds that react with ultraviolet-curable resins to terminate polymerization may also be added.

[0023] The ultraviolet light is irradiated at an appropriate illuminance and dose using, for example, a mercury lamp or a UV-LED light source. The Young's moduli of the primary layer 32, the secondary layer 33, and the colored layer 34 vary depending on the optical fiber manufacturing conditions (e.g., drawing speed, UV irradiation intensity, type of UV light source, resin application temperature, etc.), and cannot be uniquely determined by the ultraviolet-curable resin used.

[0024] The diameter of the bare optical fiber 31 may be 80 μm or more and 150 μm or less, and preferably 124 μm or more and 126 μm or less. The thickness of the primary layer 32 may be 5 μm or more and 60 μm or less. The thickness of the secondary layer 33 may be 5 μm or more and 60 μm or less. The thickness of the colored layer 34 may be approximately several μm. Here, the diameter of the optical fiber strand may be determined by the sum of the diameter of the bare optical fiber 31, the length twice the thickness of the primary layer 32, and the length twice the thickness of the secondary layer 33. Therefore, the diameter of the bare optical fiber 31, the thickness of the primary layer 32, and the thickness of the secondary layer 33 may each be selected so that the diameter of the optical fiber strand is approximately 120 to 280 μm.

[0025] [Young's modulus measurement] The Young's modulus of the primary layer 32 corresponds to the In Situ Modulus (ISM). The Young's modulus measurement (P-ISM) of the primary layer 32 is defined as being measured by the following method. First, a commercially available stripper is used to strip a few millimeters of the primary layer 32 and secondary layer 33 from the middle of a sample optical fiber. Then, one end of the optical fiber on which the coating layer is formed is fixed on a glass slide with adhesive, and a load F is applied to the other end of the optical fiber on which the coating layer is formed. In this state, the displacement δ of the primary layer 32 at the boundary between the portion where the coating layer is stripped and the portion where the coating layer is formed is measured using a microscope. A graph of the displacement δ versus the load F is then created by setting the load F to 10, 20, 30, 50, and 70 gf (i.e., 98, 196, 294, 490, and 686 mN, respectively). The primary modulus is then calculated using the slope obtained from the graph and the following equation (1). The calculated primary elastic modulus corresponds to the so-called ISM, and will be referred to as P-ISM below as appropriate. Note that when drawing the colored optical fiber 3, the drawing speed and the irradiance of the ultraviolet light were controlled to adjust the P-ISM. P-ISM=(3F / δ)*(1 / 2πl)*ln(DP / DG) (Formula 1)

[0026] Here, the unit of P-ISM is [MPa]. Furthermore, F / δ is the slope of the graph of displacement (δ) [μm] against load (F) [gf], l is the sample length (e.g., 10 mm), and DP / DG is the ratio of the outer diameter (DP) [μm] of the primary layer 32 to the outer diameter (DG) [μm] of the cladding of the optical fiber. Therefore, when calculating P-ISM using the above formula from the used F, δ, and l, a predetermined unit conversion is required. The outer diameter of the primary layer 32 and the outer diameter of the cladding can be measured by observing the cross section of the optical fiber cut with a fiber cutter under a microscope.

[0027] The Young's modulus of the secondary layer 33 was measured as follows. First, an optical fiber was immersed in liquid nitrogen, and the coating layer was stripped off using a commercially available stripper. A hollow cylindrical sample consisting of only the coating layer was prepared, and the end of the sample was fixed to an aluminum plate. Next, the aluminum plate portion was chucked using a Tensilon universal tensile tester in an atmosphere of 23°C and 50% relative humidity. Next, the sample was pulled with a width of 6 mm, a gauge spacing of 25 mm, and a pulling rate of 1 mm / min, and the force at 2.5% elongation was measured. The elastic modulus (secondary elastic modulus) S-ISM (2.5% secant modulus) of the secondary layer 33 was calculated based on the measured values. Note that the hollow cylindrical sample also contained the primary layer 32, but because the S-ISM value was sufficiently large compared to the P-ISM, the influence of the primary layer 32 was considered negligible.

[0028] Generally, the Young's modulus of the primary layer 32 can be in the range of 0.1 to 2.0 MPa, the Young's modulus of the secondary layer 33 can be in the range of 500 to 2000 MPa, and the Young's modulus of the colored layer 34 can be in the range of 500 to 2000 MPa.

[0029] Next, the Young's modulus of the tape layer 21 and the bind layer 11 will be described. Generally, the Young's modulus of the tape layer 21 and the bind layer 11 can be in the range of 10 to 2000 MPa. However, it is not easy to accurately predict the properties of the ribbon layer, which is a combination of the tape layer 21 and the bind layer 11, based on data obtained by evaluating the tape layer 21 and the bind layer 11 separately. For this reason, it is important to evaluate the tape layer 21 and the bind layer 11 together as a ribbon layer. Hereinafter, in this specification, a layered member consisting of the tape layer 21 and the bind layer 11 will be referred to as a "ribbon layer."

[0030] The Young's modulus of the ribbon layer was measured as follows. First, the ribbon layer was scraped off from one side of the splittable optical fiber ribbon 1 (the side on which the plurality of colored optical fibers 3 were arranged in parallel) using a single-edged blade or the like, and then the colored optical fibers 3 remaining on the other side together with the ribbon layer were removed. Next, the other ribbon layer was conditioned at constant temperature and humidity (23°C, 50% constant), and then prepared into a sample piece 10 with a length of 25 mm. This was pulled at a pulling rate of 1 mm / min, and the Young's modulus at 2.5% strain was calculated. FIG. 4 is a cross-sectional view showing an example of the sample piece 10 of the ribbon layer used in testing the splittable optical fiber ribbon 1. The sample piece 10 includes only the tape layer 21 and the binding layer 11. The cross-sectional area of ​​the sample piece 10 was measured using a microscope.

[0031] The storage modulus is the component of energy generated by external force and strain that is stored inside an object, and represents the elastic element of a material. In this specification, the storage modulus at 150°C is defined as the "equilibrium modulus." The storage modulus and equilibrium modulus of the ribbon layer of the dividable optical fiber ribbon 1 can be measured by dynamic mechanical analysis (DMA). Dynamic mechanical analysis is the viscoelasticity observed when a periodically changing strain or stress is applied to an object. By measuring dynamic mechanical analysis, data on the storage modulus (G'), loss modulus (G''), and loss tangent value (tan δ = G'' / G') can be obtained. Here, the loss modulus represents the viscous element of a material. The loss tangent value is the loss modulus divided by the storage modulus, and represents the balance between the elastic element and the viscous element.

[0032] In a perfectly elastic body, stress and strain are proportional, and stress is detected without delay (zero phase difference) for a given stress. In contrast, in a perfectly viscous body, stress and strain rate are proportional. Therefore, when stress is applied as sin(ωt), the response strain is -cos(ωt) = sin(ωt - π / 2), and strain is detected with a delay of 1 / 4 wavelength (phase difference π / 2) relative to stress. Measurements are performed by detecting the sample's displacement when an AC force is applied to the sample. Fourier transformations are then performed on the applied AC force and the detected displacement to determine the phase difference. Typical polymers have properties intermediate between a perfectly elastic body and a viscous body, with a phase difference between 0 and π / 2. The relationship between stress and strain is measured, and the loss tangent value, which represents the ratio of the storage modulus of the elastic component to the loss modulus of the viscous component, which are mechanical properties, is output. In this specification, the temperature at which the loss tangent value reaches its maximum is defined as the "glass transition temperature."

[0033] In this embodiment, the dynamic viscoelasticity device used was the RSA-G2 (registered trademark) manufactured by TA Instruments, and the sample piece 10 scraped off with a single-edged blade or the like was fixed to a tensile jig of the RSA-G2 (registered trademark) and measured under the dynamic viscoelasticity test conditions described below. <Dynamic viscoelasticity test conditions> Vibration frequency: 1Hz Sample heating rate: 5°C / min

[0034] FIG. 5 is a diagram showing the relationship between temperature, storage modulus, loss tangent, and glass transition temperature in the ribbon layer of the splittable optical fiber ribbon 1. In FIG. 5, the horizontal axis represents temperature, and the vertical axis represents storage modulus or loss tangent (tan δ). Line A shows the relationship between temperature and storage modulus. Line B shows the relationship between temperature and loss tangent (tan δ). In FIG. 5, the loss tangent of the ribbon layer being measured exhibits maximum values ​​at points P and Q. Hereinafter, the lowest temperature among two or more glass transition temperatures in the ribbon layer is defined as the "first glass transition temperature," and the highest temperature is defined as the "second glass transition temperature." As an example, the first glass transition temperature may be approximately -55°C, and the second glass transition temperature may be approximately 90°C. It is preferable that the first glass transition temperature of the ribbon layer is less than 25°C (room temperature), and the second glass transition temperature is 25°C or higher. It is also preferable that the difference between the first glass transition temperature and the second glass transition temperature is 85°C or higher. Although the example of FIG. 5 shows a case where the ribbon layer has two glass transition temperatures, the ribbon layer may have three or more glass transition temperatures depending on the resin composition of the ribbon layer.

[0035] 5 does not limit whether the first glass transition temperature and the second glass transition temperature of the ribbon layer correspond to the glass transition temperature of the tape layer 21 or the bind layer 11. One of the tape layer 21 and the bind layer 11 may have the first glass transition temperature, and the other may have the second glass transition temperature.

[0036] Each of the tape layer 21 and the bind layer 11 may have two or more glass transition temperatures. In this case, the lowest glass transition temperature of the tape layer 21 and the bind layer 11 is the first glass transition temperature of the ribbon layer, and the highest glass transition temperature of the tape layer 21 and the bind layer 11 is the second glass transition temperature of the ribbon layer. When each of the tape layer 21 and the bind layer 11 has two or more glass transition temperatures, the resin composition of the tape layer 21 and the bind layer 11 may be one in which two or more oligomers having different glass transition temperatures are blended into the tape layer material or the bind layer material.

[0037] In this embodiment, the ribbon layer consisting of the tape layer 21 and the bind layer 11 has a first glass transition temperature and a second glass transition temperature that are different from each other. This can improve the divisibility of the splittable optical fiber ribbon 1. Normally, when the glass transition temperature is high, the elastic modulus is high. When the glass transition temperature is low, the elastic modulus is low. For example, when the bind layer 11 has a first glass transition temperature and the tape layer 21 has a second glass transition temperature, the elastic modulus of the tape layer 21 is higher than that of the bind layer 11. On the other hand, when the tape layer 21 has a first glass transition temperature and the bind layer 11 has a second glass transition temperature that is higher than the first glass transition temperature, the elastic modulus of the bind layer 11 is higher than that of the tape layer 21. In either case, a difference occurs between the elastic modulus of the tape layer 21 and that of the bind layer 11. From the viewpoint of improving divisibility, it is preferable to set the elastic modulus of the tape layer 21 higher than that of the bind layer 11.

[0038] In this embodiment, the equilibrium elastic modulus of the ribbon layer is set low. Specifically, the equilibrium elastic modulus of the ribbon layer is 44.7 MPa or less. This improves the individual fiber separation property of the splittable optical fiber ribbon 1. Normally, if the breaking elongation of the ribbon layer is set low, the ribbon layer itself is easily torn when peeled off from the colored optical fiber 3, resulting in poor individual fiber separation property. For this reason, the ribbon layer is required to have a certain degree of breaking elongation. Meanwhile, the breaking elongation depends on the crosslink density and the molecular weight between crosslink points, and there is a correlation between the breaking elongation and the equilibrium elastic modulus. In other words, the higher the breaking elongation, the lower the equilibrium elastic modulus. For this reason, by setting the equilibrium elastic modulus of the ribbon layer low, the breaking elongation of the ribbon layer can be increased.

[0039] Next, the divisibility and single-fiber separability of the separable optical fiber ribbon 1 according to this embodiment will be described in detail. FIG. 6 is a diagram illustrating the divisibility and single-fiber separability of the separable optical fiber ribbon 1. FIG. 6(a) is a diagram illustrating the separable optical fiber ribbon 1 before being divided. FIG. 6(b) shows a state in which the single separable optical fiber ribbon 1 shown in FIG. 6(a) has been divided into two bundled optical fiber ribbons 2. In the example of FIG. 6(b), although pieces of the binding layer 11 remain in each of the two bundled optical fiber ribbons 2 at the cross section of the binding layer 11, there is no damage to the tape layers 21 of the two bundled optical fiber ribbons 2. FIG. 6(c) shows a state in which the two divided bundled optical fiber ribbons 2 shown in FIG. 6(b) have been separated into four colored optical fiber ribbons 3.

[0040] 7A to 7F show an example of dividing one splittable optical fiber ribbon 1 into two bundled optical fiber tapes 2. Figs. 7A to 7E show an example of good (A) evaluation of splittability, and Fig. 7F shows an example of poor (N) evaluation of splittability.

[0041] In the example of Fig. 7A, no binding layer 11 remains in each of the two bundled optical fiber ribbons 2, and there is no damage to the tape layers 21 of the two bundled optical fiber ribbons 2. Therefore, the example of Fig. 7A is evaluated as good (A) in terms of splittability.

[0042] In the example of Fig. 7B, pieces of the binding layer 11 remain in each of the two bundled optical fiber ribbons 2 at the cross section of the binding layer 11, but there is no damage to the ribbon layer 21. Therefore, the example of Fig. 7B is evaluated as good (A) in terms of divisibility.

[0043] In the example of Figure 7C, in the cross section of the binding layer 11, pieces of the binding layer 11 remain in each of the two bundled optical fiber ribbons 2, but there is no damage to the tape layers 21 of the two bundled optical fiber ribbons 2. Similarly, in the example of Figure 7D, pieces of the binding layer 11 remain in each of the two bundled optical fiber ribbons 2, but there is no damage to the tape layers 21 of the two bundled optical fiber ribbons 2. Therefore, the examples of Figures 7C and 7D are evaluated as good (A) in terms of divisibility.

[0044] In the example of Fig. 7E, although the pieces of the binding layer 11 are separated from the two bundled optical fiber ribbons 2, there is no damage to the tape layers 21 of the two bundled optical fiber ribbons 2. Therefore, the example of Fig. 7E is evaluated as good (A) in the evaluation of divisibility.

[0045] In the example of Fig. 7F, the tape layers 21 of the two bundled optical fiber ribbons 2 are damaged, and the tape layers 21 are separated from the bundled optical fiber ribbon 2. Therefore, the example of Fig. 7F is evaluated as poor (N) in the evaluation of divisibility. In addition to the example of Fig. 7F, if the bundled optical fiber ribbon 2 cannot be divided, if the tape layers 21 are damaged to a degree that is visible to the naked eye, or if the tape layers 21 are damaged and separated from the bundled optical fiber ribbon 2, the evaluation of divisibility is also evaluated as poor (N).

[0046] [Effective core area and microbend loss] An index indicating the likelihood of microbend loss in an optical fiber is the effective core area (Aeff). 2 or more (≧60μm 2 ) optical fiber is used. In optical fibers, Aeff is an index of microbending sensitivity, and the larger Aeff, the higher the microbending sensitivity. Generally, 2 If Aeff is greater than 130μm, the microbend sensitivity is said to be high. 2More than 150μm 2 If the effective core area (Aeff) is less than 1 / 2, the optical fiber has a high microbending sensitivity without any problems. 2 It is expressed by the formula ×π×k / 4 (where MFD is the mode field diameter (μm) and k is a constant), and is described, for example, in C-3-76 and C-3-77 of the 1999 Electronics Society Conference Proceedings of the Institute of Electronics, Information and Communication Engineers. It is assumed that Aeff is measured at 1550 nm.

[0047] The optical fiber and colored optical fiber 3 according to this embodiment have a microbend loss of 0.3 dB / km or less, preferably 0.2 dB / km or less, and more preferably 0.1 dB / km or less.

[0048] There are various possible methods for measuring microbend loss. In this specification, the microbend loss value is defined as the difference between the transmission loss of the optical fiber to be measured in State A, where an optical fiber 400 m or longer is wound in a single layer without overlapping at a tension of 100 gf around a large bobbin wrapped with #1000 grit sandpaper, and the transmission loss of the optical fiber in State B, where the optical fiber is wound on the same bobbin as State A with the same tension and length as State A but without sandpaper. Here, the transmission loss of the optical fiber in State B does not include microbend loss and is considered to be the transmission loss inherent to the optical fiber itself.

[0049] This measurement method is similar to the fixed diameter drum method specified in JIS C6823:2010. This measurement method is also called the sandpaper method. In this measurement method, the transmission loss is measured at a wavelength of 1550 nm, so the microbend loss in this specification is also a value measured at a wavelength of 1550 nm.

[0050] 8 is a schematic diagram of a manufacturing apparatus 5 used in the manufacturing method of the splittable optical fiber ribbon 1 in this embodiment. The manufacturing apparatus 5 includes a fiber holding device 51, a guide roller 52, a tape layer coating device 53, a binding layer coating device 54, a guide roller 55, a winding device 56, and a control device 7.

[0051] The fiber holding device 51 winds and holds the manufactured colored optical fiber 3. The colored optical fiber 3 is pulled out from the fiber holding device 51, guided by guide rollers 52, and transported to the tape layer coating device 53. The number of fiber holding devices 51 and guide rollers 52 can vary depending on the number of colored optical fiber 3 in the segmentable optical fiber ribbon 1. In this embodiment, the bundled optical fiber ribbon 2 is manufactured using two colored optical fiber 3, and the segmentable optical fiber ribbon 1 is manufactured using two bundled optical fiber ribbons 2. Therefore, the number of fiber holding devices 51 and the number of guide rollers 52 are four. The fiber holding devices 51A, 53B, 51C, and 51D each hold the colored optical fiber 3, and the guide rollers 52A, 52B, 52C, and 52D each transport the colored optical fiber 3 to the tape layer coating device 53.

[0052] The tape layer coating device 53 includes a resin applicator 531 and an ultraviolet ray irradiator 532. The resin applicator 531 holds an ultraviolet-curable resin and applies the ultraviolet-curable resin to the outer periphery of the colored optical fiber 3. The resin applicator 531 is also called a coating die or a die. The ultraviolet ray irradiator 532 includes a UV light source 533 such as a metal halide lamp, a mercury lamp, or a UV-LED light source, and is provided downstream of the resin applicator 531 (corresponding to the lower part in FIG. 8 ). The ultraviolet ray irradiator 532 is also called a curing furnace, and irradiates ultraviolet rays onto the colored optical fiber 3 coated with the ultraviolet-curable resin to form the tape layer 21. The UV light source 533 is provided to surround the outer periphery of the colored optical fiber 3. The tape layer coating device 53 may include multiple ultraviolet ray irradiators 532. When multiple ultraviolet ray irradiators 532 are provided, the multiple ultraviolet ray irradiators 532 are provided in series in the transport direction of the colored optical fiber 3. By providing a plurality of ultraviolet irradiation devices 532, it is possible to extend the time for irradiating ultraviolet rays onto the ultraviolet curable resin. Note that by measuring the surface temperature of the tape layer 21 immediately after ultraviolet irradiation by the UV light source 533 (at the outlet 534 of the ultraviolet irradiation device 532 in FIG. 8), it is possible to measure the temperature of the tape layer 21 immediately after the ultraviolet curable resin has hardened.

[0053] While the colored optical fiber 3 passes through the inside of the ultraviolet irradiation device 532, the UV light source 533 irradiates ultraviolet light onto the ultraviolet curable resin coated on the outer periphery of the colored optical fiber 3. The ultraviolet curable resin coated on the outer periphery of the colored optical fiber 3 hardens to form a tape layer 21. In this way, two bundled optical fiber ribbons 2 are formed. The two bundled optical fiber ribbons 2 are transported from the tape layer coating device 53 and transported to the binding layer coating device 54, respectively.

[0054] The binding layer coating device 54 has a configuration similar to that of the tape layer coating device 53 and includes a resin applicator 541 and an ultraviolet ray irradiator 542. The resin applicator 541 holds an ultraviolet ray curable resin and applies the ultraviolet ray curable resin to the outer periphery of the two bundled optical fiber ribbons 2. The resin applicator 541 is also called a coating die or a die. The ultraviolet ray irradiator 542 includes a UV light source 543 such as a metal halide lamp, a mercury lamp, or a UV-LED light source, and is provided downstream of the resin applicator 541 (corresponding to the lower part in FIG. 8 ). The ultraviolet ray irradiator 542 is also called a curing furnace, and irradiates ultraviolet rays onto the bundled optical fiber ribbons 2 to which the ultraviolet ray curable resin has been applied, thereby forming the binding layer 11. The UV light source 543 is provided so as to surround the outer periphery of the bundled optical fiber ribbon 2. As with the tape layer coating device 53, the binding layer coating device 54 may also be provided with a plurality of ultraviolet ray irradiators 542. When multiple ultraviolet irradiation devices 542 are provided, the multiple ultraviolet irradiation devices 542 are provided in series in the transport direction of the bundled optical fiber ribbon 2. By providing multiple ultraviolet irradiation devices 542, the time for irradiating the ultraviolet curable resin with ultraviolet rays can be extended. As with the tape layer coating device 53, the surface temperature of the binding layer 11 can be measured immediately after ultraviolet irradiation by the UV light source 543 (at the outlet 544 of the ultraviolet irradiation device 542 in FIG. 8), thereby measuring the temperature of the binding layer 11 immediately after the ultraviolet curable resin is cured.

[0055] While the bundled optical fiber ribbon 2 passes through the inside of the ultraviolet irradiation device 542, ultraviolet light is irradiated from a UV light source 543 onto the ultraviolet curable resin coated on the outer periphery of the bundled optical fiber ribbon 2. The ultraviolet curable resin coated on the outer periphery of the two bundled optical fiber ribbons 2 is cured to form a binding layer 11. Through the above steps, the separable optical fiber ribbon 1 is manufactured. The separable optical fiber ribbon 1 is transported from the binding layer coating device 54, and is transported via a guide roller 55 to a winding device 56 and wound up.

[0056] The control device 7 controls, for example, the conveying speed of the guide rollers 52A, 52B, 52C, 52D and the guide roller 55, the pressure when pressurizing and supplying the ultraviolet-curable resin in the tape layer coating device 53 and the bind layer coating device 54, the temperature of the ultraviolet-curable resin supplied to the resin application device 531 and the resin application device 541, the outlet diameter of the tape layer coating device 53 and the bind layer coating device 54, the intensity of the UV light source of the ultraviolet irradiation device 532 and the ultraviolet irradiation device 542, the internal temperature of the tape layer coating device 53 and the bind layer coating device 54, the winding torque of the winding device 56, etc.

[0057] 9 is a block diagram of the control device 7 in this embodiment. The control device 7 has a CPU (Central Processing Unit) 701, a ROM (Read Only Memory) 702, a RAM (Random Access Memory) 703, a storage device 704, a display 705, a touch sensor 706, an input device 707, a communication I / F 708, and a sensor I / F 709. Each unit is connected to each other via a bus 710.

[0058] The CPU 701 controls each part of the manufacturing apparatus 5 using an application program. The ROM 702 is made up of a non-volatile memory and stores the application program for controlling each part of the manufacturing apparatus 5. The RAM 703 provides a memory area necessary for the operation of the CPU 701. The storage device 704 is made up of a hard disk, a semiconductor memory, etc.

[0059] The display 705 is configured by, for example, a liquid crystal display, an OLED (organic light emitting diode) display, an LED (light emitting diode) display, etc. A touch sensor 706 is disposed on the surface of the display 705. The touch sensor 706 includes a capacitance-type or resistance-type detection circuit. The input device 707 is a user I / F and may be, for example, a keyboard, a mouse, etc.

[0060] The communication I / F 708 is a communication unit that transmits and receives data, and communicatively connects the control device 7 with the tape layer coating device 53 and the bind layer coating device 54. Communication between the control device 7 and the manufacturing device 5 via the communication I / F 708 may be either wired communication or wireless communication. The wireless communication method may be, for example, third-generation mobile communication, LTE (Long Term Evolution), fourth-generation mobile communication, fifth-generation mobile communication, short-range wireless communication such as Bluetooth (registered trademark), or wireless communication via a wireless LAN connection such as Wi-Fi.

[0061] The sensor I / F 709 acquires various data from sensors included in the manufacturing apparatus 5 and stores the data in the storage device 704 or the like. The various data may be, for example, the temperature of the ultraviolet curable resin supplied to the resin application device 531 and the resin application device 541, the pressure when the ultraviolet curable resin is pressurized and supplied, the temperature of the tank storing the ultraviolet curable resin, the intensity of the UV light sources 533 and 543, the internal temperatures of the tape layer coating device 53 and the bind layer coating device 54, the surface temperature of the colored optical fiber 3, the surface temperature of the bundled optical fiber tape 2, the surface temperature of the split optical fiber ribbon 1, and the like.

[0062] The control device 7 receives control parameters for the manufacturing apparatus 5 through an operation by an operator, and controls the manufacturing apparatus 5. The control device 7 also receives information from a sensor (not shown) provided in the manufacturing apparatus 5 via a sensor I / F 709, and can calculate the conveying speed of the guide rollers 52A, 52B, 52C, 52D and the guide roller 55, the temperature of a tank storing the ultraviolet-curable resin supplied to the resin applicator 531 and the resin applicator 541, the surface temperature of the colored optical fiber 3, the surface temperature of the bundled optical fiber tape 2, the surface temperature of the separable optical fiber ribbon 1, the internal temperature of the tape layer coating device 53, and the internal temperature of the bind layer coating device 54, and can reflect these in the control of the manufacturing apparatus 5.

[0063] FIG. 10 is a flowchart of a method for manufacturing a splittable optical fiber ribbon 1 according to this embodiment. First, an optical fiber preform is placed in a drawing device (not shown) (step S101). The optical fiber preform is heated with a heater, and a bare optical fiber 31 is drawn (step S102). An ultraviolet-curable resin is applied to the outer periphery of the drawn bare optical fiber 31, and ultraviolet light is applied to form a primary layer 32 (step S103). An ultraviolet-curable resin is applied to the outer periphery of the primary layer 32, and ultraviolet light is applied to form a secondary layer 33 (step S104). An optical fiber is obtained by steps S101 to S104. A colored ultraviolet-curable resin is applied to the outer periphery of the optical fiber, and ultraviolet light is applied to form a colored layer 34 (step S105). A colored optical fiber 3 is obtained by steps S101 to S105. The manufactured colored optical fiber 3 is wound around a fiber holding device 51. Steps S101 to S105 are performed for each colored optical fiber 3.

[0064] The manufacturing apparatus 5 carries the colored optical fiber core wires 3 from the core wire holding devices 51A, 53B, 51C, and 51D into the tape layer coating device 53. The multiple colored optical fiber core wires 3 are arranged in parallel inside the tape layer coating device 53. The tape layer coating device 53 then forms a tape layer 21 on the parallelly arranged colored optical fiber core wires 3 (step S106). By forming the tape layer 21 around the outer periphery of the colored optical fiber core wires 3, two bundled optical fiber ribbon core wires 2 are obtained from the four colored optical fiber core wires 3. The specific process of forming the tape layer 21 in step S106 will be described in detail with reference to FIG. 11.

[0065] The manufacturing apparatus 5 carries the bundled optical fiber ribbons 2 from the tape layer coating device 53 into the binding layer coating device 54. The bundled optical fiber ribbons 2 are arranged in parallel inside the binding layer coating device 54. The binding layer coating device 54 then forms a binding layer 11 on the bundled optical fiber ribbons 2 arranged in parallel (step S107). By forming the binding layer 11 around the outer periphery of the two bundled optical fiber ribbons 2, one separable optical fiber ribbon 1 is obtained. The separable optical fiber ribbon 1 is taken up by the take-up device 56. The specific process of forming the binding layer 11 in step S107 will be described in detail with reference to FIG. 12.

[0066] FIG. 11 is a flowchart of a manufacturing method of the tape layer 21 in this embodiment. First, the manufacturing apparatus 5 sets the light source output of the UV light source 533, the irradiation time of ultraviolet light to the ultraviolet curable resin, the temperature of the ultraviolet curable resin, etc. (Step S201). The output of the UV light source 533 is set in the range of 0 to 100%, with the maximum output of the UV light source 533 being 100%. The irradiation time of ultraviolet light to the ultraviolet curable resin is set by controlling the linear speed of the colored optical fiber 3 as it passes through the ultraviolet irradiation device 532. Also, as described in FIG. 8, the irradiation time of ultraviolet light to the ultraviolet curable resin can be controlled by providing multiple ultraviolet irradiation devices 532. The temperature of the ultraviolet curable resin is set by an operator or the like via the control device 7. The predetermined temperature can be, for example, in the range of 25°C (room temperature) to 50°C.

[0067] The manufacturing apparatus 5 heats the ultraviolet-curable resin held in the tape layer coating device 53 to a predetermined temperature based on the temperature of the ultraviolet-curable resin set in step S201 (step S202). The ultraviolet-curable resin may be heated inside the tape layer coating device 53, or may be heated in a tank (not shown) that stores the ultraviolet-curable resin and supplies it to the tape layer coating device 53. When applying the ultraviolet-curable resin to the colored optical fiber 3, it is preferable that the ultraviolet-curable resin be heated so that its temperature is the temperature set in step S201. The temperature of the ultraviolet-curable resin is measured using a thermocouple-type thermometer.

[0068] When the temperature of the ultraviolet curing resin reaches a predetermined temperature, the manufacturing apparatus 5 transports each of the four colored optical fiber core wires 3 wound around the core wire holding device 51 to the tape layer coating device 53. In the tape layer coating device 53, the resin coating device 531 applies ultraviolet curing resin to the outer periphery of the colored optical fiber core wire 3 (step S203). Furthermore, the ultraviolet irradiation device 532 irradiates the ultraviolet curing resin with ultraviolet light for a predetermined irradiation time to form the tape layer 21 around the outer periphery of the colored optical fiber core wire 3 (step S204). The UV light source provided in the ultraviolet irradiation device 532 can be, for example, a mercury lamp, a UV-LED light source, or the like.

[0069] Through steps S201 to S204, the tape layer 21 is formed around the outer periphery of the colored optical fiber core wires 3, and two bundled optical fiber ribbon core wires 2 are obtained from the four colored optical fiber core wires 3.

[0070] 12 is a flowchart of a method for manufacturing the bind layer 11 in this embodiment. First, the manufacturing apparatus 5 sets the light source output of the UV light source 543 and the irradiation time of ultraviolet light to the ultraviolet-curable resin (step S301). The output of the UV light source 543 is set in the range of 0 to 100%, with the maximum output of the UV light source 543 being 100%. The output of the UV light source 543 when forming the bind layer 11 is preferably smaller than the output of the UV light source 533 when forming the tape layer 21.

[0071] The irradiation time of the ultraviolet curable resin with ultraviolet rays is set by controlling the linear speed of the bundled optical fiber ribbon 2 as it passes through the ultraviolet irradiation device 542. The irradiation time of the ultraviolet curable resin with ultraviolet rays when forming the bind layer 11 is preferably shorter than the irradiation time of the ultraviolet curable resin when forming the tape layer 21. By providing multiple ultraviolet irradiation devices 532 in the tape layer coating device 53, the irradiation time of ultraviolet rays when forming the bind layer 11 may be shorter than the irradiation time of ultraviolet rays when forming the tape layer 21. For example, if the tape layer coating device 53 is provided with two ultraviolet irradiation devices 532 and the bind layer coating device 54 is provided with one ultraviolet irradiation device 542, the irradiation time of ultraviolet rays when forming the bind layer 11 will be approximately half the irradiation time of ultraviolet rays when forming the tape layer 21. Furthermore, the temperature of the ultraviolet curable resin may be set. For example, the temperature of the ultraviolet curable resin may be room temperature, or the ultraviolet curable resin may be heated to a predetermined temperature.

[0072] The manufacturing apparatus 5 transports the two bundled optical fiber ribbons 2 from the ribbon layer coating apparatus 53 to the binding layer coating apparatus 54. In the binding layer coating apparatus 54, a resin applicator 541 applies an ultraviolet curable resin to the outer peripheries of the two bundled optical fiber ribbons 2 (step S302). When applying the ultraviolet curable resin, the ultraviolet curable resin may be heated to a predetermined temperature. The ultraviolet curable resin may be heated inside the binding layer coating apparatus 54, or may be heated in a tank (not shown) that stores the ultraviolet curable resin and supplies it to the binding layer coating apparatus 54. Furthermore, the ultraviolet irradiation apparatus 542 irradiates the ultraviolet curable resin with ultraviolet light for a predetermined irradiation time to form a binding layer 11 around the outer peripheries of the two bundled optical fiber ribbons 2 (step S303). The UV light source provided in the ultraviolet irradiation apparatus 542 may be, for example, a mercury lamp, a UV-LED light source, or the like.

[0073] Through steps S301 to S303, a binding layer 11 is formed around the two bundled optical fiber ribbons 2, and one separable optical fiber ribbon 1 is obtained by connecting the two bundled optical fiber ribbons 2 together.

[0074] According to the splittable optical fiber ribbon 1 of this embodiment, the ribbon layer consisting of the tape layer 21 and the binding layer 11 has a first glass transition temperature and a second glass transition temperature that are different from each other. In addition, the equilibrium modulus of the tape layer 21 and the binding layer 11 is 44.7 MPa or less. This provides a splittable optical fiber ribbon 1 that combines "splittability" and "single fiber separability."

[0075] [Example] Next, Examples 1 to 11 of the present invention and Comparative Examples 1 to 3 will be described. The test results for Examples 1 to 11 and Comparative Examples 1 to 3 are shown in Table 1 below. [Table 1]

[0076] Table 1 shows the first glass transition temperature, second glass transition temperature, equilibrium modulus, storage modulus at -50°C, and storage modulus at 25°C of the ribbon layer of a four-core split optical fiber ribbon (two two-core ribbons bound together).

[0077] Furthermore, in the evaluation results of splittability in Table 1, if the splittable optical fiber ribbon 1 could be split into a plurality of bundled optical fiber tape 2 at the middle portion, not at the ends, using a dedicated tool, it was rated as good (A). In other words, if the bundled optical fiber tape 2 collapsed into a single fiber state, or if the binding layer 11 did not collapse and splitting was not possible, it was rated as poor (N). Also, if it could be split without using a dedicated tool, it was rated as poor (N). Note that the number of fibers in the splittable optical fiber ribbon 1 is not limited to 4, and sufficient splittability can be obtained with other numbers of fibers (e.g., 8, 12, 24, etc.) by appropriately controlling the hardening characteristics of the tape layer 21.

[0078] Furthermore, the evaluation results of the fiber separation ability in Table 1 were evaluated by whether or not it was possible to separate colored optical fiber 3 having a size of 30 cm to 50 cm in the longitudinal direction into single fibers by cracking the ribbon layer from the end of the splittable optical fiber ribbon 1 without using any special tools, and then removing the ribbon layer. If the colored optical fiber 3 could be neatly removed from the ribbon layer without peeling or breaking of the colored layer 34, and without any of the ribbon layer skin remaining on the colored optical fiber 3, it was evaluated as good (A).

[0079] However, if separation of the fibers was possible but the ribbon layer tore after two to five attempts to separate the fibers, or if the separation was time-consuming, the fiber separation ability was evaluated as fair (B). If peeling or breakage of the colored layer 34 occurred, or if the ribbon layer tore after five or more attempts to separate the fibers, the fiber separation ability was evaluated as poor (N). Note that the number of fibers in the splittable optical fiber ribbon 1 is not limited to four, and even in cases of other numbers of fibers (e.g., 8, 12, 24, etc.), sufficient fiber separation ability can be obtained by appropriately controlling the hardening characteristics of the ribbon layer.

[0080] Note that 25°C and -50°C are temperatures assuming the use of a four-core split optical fiber ribbon in a room temperature environment and a low temperature environment, respectively. Since it is necessary to maintain splittability and single-core separation in these temperature environments, the storage modulus at these temperatures was investigated.

[0081] [Example 1] In Example 1, a ribbon layer was used having a first glass transition temperature of -54.6°C, a second glass transition temperature of 92.0°C, an equilibrium modulus of 11.6 MPa, a storage modulus of 2990 MPa at -50°C, and a storage modulus of 1310 MPa at 25°C. In Example 1, the divisibility was evaluated as good (A) and the single-core separability was evaluated as good (A).

[0082] [Example 2] In Example 2, a ribbon layer was used having a first glass transition temperature of -55.2°C, a second glass transition temperature of 98.1°C, an equilibrium modulus of 11.8 MPa, a storage modulus of 2980 MPa at -50°C, and a storage modulus of 1250 MPa at 25°C. In Example 2, the divisibility was evaluated as good (A) and the single-core separation property was evaluated as good (A).

[0083] [Example 3] In Example 3, a ribbon layer was used having a first glass transition temperature of -53.6°C, a second glass transition temperature of 98.6°C, an equilibrium modulus of 12.9 MPa, a storage modulus of 3150 MPa at -50°C, and a storage modulus of 1160 MPa at 25°C. In Example 3, the divisibility was evaluated as good (A) and the single-core separation property was evaluated as good (A).

[0084] [Example 4] In Example 4, a ribbon layer was used having a first glass transition temperature of -54.5°C, a second glass transition temperature of 59.2°C, an equilibrium modulus of 27.2 MPa, a storage modulus of 3190 MPa at -50°C, and a storage modulus of 1230 MPa at 25°C. In Example 4, the divisibility was evaluated as good (A) and the single-core separability was evaluated as good (A).

[0085] [Example 5] In Example 5, a ribbon layer was used having a first glass transition temperature of -52.8°C, a second glass transition temperature of 68.4°C, an equilibrium modulus of 39.9 MPa, a storage modulus of 3210 MPa at -50°C, and a storage modulus of 1330 MPa at 25°C. In Example 5, the divisibility was evaluated as good (A) and the single-core separability was evaluated as good (A).

[0086] [Example 6] In Example 6, a ribbon layer was used having a first glass transition temperature of -53.6°C, a second glass transition temperature of 62.4°C, an equilibrium modulus of 33.2 MPa, a storage modulus of 3310 MPa at -50°C, and a storage modulus of 1390 MPa at 25°C. In Example 6, the divisibility was evaluated as good (A) and the single-core separation property was evaluated as good (A).

[0087] [Example 7] In Example 7, a ribbon layer was used having a first glass transition temperature of -54.3°C, a second glass transition temperature of 61.3°C, an equilibrium modulus of 24.9 MPa, a storage modulus of 3060 MPa at -50°C, and a storage modulus of 1050 MPa at 25°C. In Example 7, the divisibility was evaluated as good (A) and the single-core separation property was evaluated as good (A).

[0088] [Example 8] In Example 8, a ribbon layer was used having a first glass transition temperature of -24.2°C, a second glass transition temperature of 98.7°C, an equilibrium modulus of 11.8 MPa, a storage modulus of 3040 MPa at -50°C, and a storage modulus of 1280 MPa at 25°C. In Example 8, the divisibility was evaluated as good (A) and the single-core separation property was evaluated as good (A).

[0089] [Example 9] In Example 9, a ribbon layer was used having a first glass transition temperature of -23.5°C, a second glass transition temperature of 61.5°C, an equilibrium modulus of 25.1 MPa, a storage modulus of 3220 MPa at -50°C, and a storage modulus of 1070 MPa at 25°C. In Example 9, the divisibility was evaluated as good (A) and the single-core separability was evaluated as good (A).

[0090] [Example 10] In Example 10, a ribbon layer was used having a first glass transition temperature of -53.5°C, a second glass transition temperature of 80.3°C, an equilibrium modulus of 44.3 MPa, a storage modulus at -50°C of 3380 MPa, and a storage modulus at 25°C of 1160 MPa. In Example 10, the divisibility was evaluated as good (A). On the other hand, although single fiber separation was possible, the separation was somewhat time-consuming, and therefore the single fiber separability was evaluated as fair (B).

[0091] [Example 11] In Example 11, a ribbon layer was used having a first glass transition temperature of -53.6°C, a second glass transition temperature of 83.3°C, an equilibrium modulus of 44.7 MPa, a storage modulus at -50°C of 3000 MPa, and a storage modulus at 25°C of 1250 MPa. The detachability in Example 11 was evaluated as good (A). On the other hand, although single fiber separation was possible, the separation took some time and effort, so the single fiber separability was evaluated as fair (B).

[0092] [Comparative Example 1] In Comparative Example 1, there was no ribbon layer corresponding to the first glass transition temperature, and a ribbon layer was used having a second glass transition temperature of 100.4°C, an equilibrium modulus of 12.5 MPa, a storage modulus of 3980 MPa at -50°C, and a storage modulus of 1940 MPa at 25°C. In Comparative Example 1, the splitting ability was evaluated as poor (N), and the single-core separation ability was evaluated as good (A).

[0093] Comparative Example 2 In Comparative Example 2, a ribbon layer was used whose first glass transition temperature was -54.2°C, there was no corresponding second glass transition temperature, and whose equilibrium modulus was 19.8 MPa, whose storage modulus at -50°C was 1290 MPa, and whose storage modulus at 25°C was 110 MPa. In Comparative Example 2, the splitting ability was evaluated as poor (N), and the single-core separation ability was evaluated as good (A).

[0094] Comparative Example 3 In Comparative Example 3, a ribbon layer was used having a first glass transition temperature of -53.5°C, a second glass transition temperature of 82.5°C, an equilibrium modulus of 50.1 MPa, a storage modulus of 3650 MPa at -50°C, and a storage modulus of 2120 MPa at 25°C. In Comparative Example 3, the splitting ability was evaluated as good (A), and the single-core separation ability was evaluated as poor (N).

[0095] As described above, according to the splittable optical fiber ribbon 1 of Examples 1-11, when the ribbon layers have different first and second glass transition temperatures, good "splittability" and "single fiber separability" can be obtained. Furthermore, based on the results of Examples 1-11, it was found that it is preferable that the first glass transition temperature is less than 25°C (room temperature) and the second glass transition temperature is 25°C or higher. More preferably, the difference between the first and second glass transition temperatures is 85°C or higher. Furthermore, it was found that good "single fiber separability" can be obtained when the equilibrium elastic modulus of the ribbon layer is 44.7 MPa or lower.

[0096] Furthermore, from Examples 1-11 and Comparative Examples 1-3, it was confirmed that the ribbon layer having two or more glass transition temperatures tends to improve "splittability." Furthermore, the ribbon layer's equilibrium modulus of 44.7 MPa or less tends to improve "single-fiber separability." A low storage modulus makes it difficult to remove the binding layer 11, which is disadvantageous in terms of splittability, while a too high storage modulus tends to lower the elongation at break, which is disadvantageous in terms of single-fiber separability. From these results, it was confirmed that the ribbon layer's storage modulus at room temperature (25°C) is preferably 1050 MPa or more and 1390 MPa or less. It was also found that the equilibrium modulus is preferably 11.6 MPa or more and 39.9 MPa or less.

[0097] The present invention is not limited to the above-described embodiments and various modifications are possible. For example, an example in which a part of the configuration of one embodiment is added to another embodiment, or an example in which a part of the configuration of another embodiment is replaced with another embodiment, is also an embodiment of the present invention. Furthermore, with respect to parts not specifically explained or illustrated in the embodiments, well-known or publicly known techniques in the relevant technical field can be applied as appropriate. [Explanation of symbols]

[0098] 1: Split optical fiber ribbon 2: Integrated optical fiber ribbon 3: Colored optical fiber core 11: Binding layer 21: Tape layer

Claims

1. a plurality of colored optical fiber cores arranged in parallel; a tape layer that covers the plurality of colored optical fibers and connects the plurality of colored optical fibers to form an integrated optical fiber tape; a binding layer that covers the plurality of bundled optical fiber ribbons arranged in parallel and connects the plurality of bundled optical fiber ribbons to form a splittable optical fiber ribbon; Equipped with the ribbon layer consisting of the tape layer and the bind layer has a first glass transition temperature and a second glass transition temperature which are different from each other; The equilibrium elastic modulus of the ribbon layer is 44.7 MPa or less. A splittable optical fiber ribbon.

2. The first glass transition temperature is less than 25°C, and the second glass transition temperature is 25°C or higher.

2. The splittable optical fiber ribbon according to claim 1.

3. the difference between the first glass transition temperature and the second glass transition temperature is 85°C or more; 2. The splittable optical fiber ribbon according to claim 1.

4. The equilibrium elastic modulus of the ribbon layer is 39.9 MPa or less.

2. The splittable optical fiber ribbon according to claim 1.

5. The equilibrium elastic modulus of the ribbon layer is 11.6 MPa or more.

2. The splittable optical fiber ribbon according to claim 1.

6. The storage modulus of the ribbon layer at 25 ° C. is 1050 MPa or more.

2. The splittable optical fiber ribbon according to claim 1.

7. The storage modulus of the ribbon layer at 25 ° C. is 1390 MPa or less.

2. The splittable optical fiber ribbon according to claim 1.

8. arranging a plurality of colored optical fiber cores in parallel; a step of covering the plurality of colored optical fibers and forming a tape layer that connects the plurality of colored optical fibers to form an integrated optical fiber ribbon; forming a binding layer that covers the plurality of bundled optical fiber ribbons arranged in parallel and connects the plurality of bundled optical fiber ribbons to form a splittable optical fiber ribbon; Equipped with the ribbon layer consisting of the tape layer and the bind layer has a first glass transition temperature and a second glass transition temperature which are different from each other; A method for manufacturing a splittable optical fiber ribbon, wherein the equilibrium elastic modulus of the ribbon layer is 44.7 MPa or less.

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