Tapes and optical fiber units for bundled optical fiber cores

Abstract

This invention provides an optical fiber core bundleing tape suitable for bundled optical fiber cores using a single bunching method in which the tape is wrapped spirally around an optical fiber core bundle, and an optical fiber unit formed using this bundleing tape. [Solution] An optical fiber core bundling tape 1 is constructed by spirally wrapping a single tape around the outer circumference of an optical fiber core bundle. The tape has a cross section perpendicular to the longitudinal direction, with a sea component 11 made of a first thermoplastic resin containing multiple island components 12 made of a second thermoplastic resin having a melting point 20°C or more higher than that of the first thermoplastic resin. The tape has a width w of 3.2 to 5.0 mm, a thickness t of 0.12 mm or less, a tensile elongation of 20 to 50%, and a thermal shrinkage rate of 1.1 to 1.5% when heated at 100°C for 3 hours.

Description

Technical Field

[0001] The present invention relates to an optical fiber core wire binding tape for binding an optical fiber core wire and an optical fiber unit bound by the binding tape.

Background Art

[0002] In high-density optical fiber cables, for example, an optical fiber unit in which a large number of optical fiber core wires are bound by a tape-shaped or string-shaped bundling material is used. As the bundling material used for such an optical fiber unit, a flat sea-island type composite fiber or tape composed of two types of thermoplastic resins having different melting points has been proposed (see, for example, Patent Documents 1 to 3).

[0003] Patent Document 1 proposes an optical fiber unit binding fiber that is suitable for the "cross bundling method" in which two bundling materials are wound in different twisting directions and the crossing portion is heat-sealed. The heat shrinkage rate after heating at 80°C for 6 hours is 0.2% or less, and the two binding fibers are crossed at an intersection angle of 90°. When heat pressure bonding and heat sealing are performed at 150°C and 0.0245 MPa for 20 seconds, the intersection flatness rate of the binding fibers is 50% or more.

[0004] Further, Patent Document 2 proposes an optical fiber unit binding fiber used for the "single bundling method" in which one bundling material is wound in a spiral shape. The melting start temperature of the sea component is 100°C or higher, the melting peak temperature is 120 to 150°C, the width is 0.5 to 3.0 mm, the thickness is 0.15 mm or less, and the heat shrinkage rate after heating at 100°C for 3 hours is 1.0% or less.

[0005] Furthermore, Patent Document 3 proposes a tape for bundling optical fiber cores, in which the melting point of the marine component resin is 150-230°C, the melting point of the island component resin is 200-260°C, the melting point of the island component resin is 20°C or more higher than the melting point of the marine component resin, the tensile modulus is 4000-10000 MPa, and the diameter of the island component resin is 10-60 μm. On the other hand, an optical fiber unit using a bundle material with a thermal shrinkage rate of 1.03% or less has also been proposed to allow for easy removal of optical fiber cores during branching operations (see Patent Document 4). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2013-037253 [Patent Document 2] International Publication No. 2014 / 024720 [Patent Document 3] Japanese Patent Publication No. 2021-157175 [Patent Document 4] Japanese Patent Publication No. 2014-219530 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, the conventional bundle materials mentioned above have the following problems. The bundle materials described in Patent Documents 1 and 3 are intended for cross-bunching systems, so when used in a single-bunching system, the bundle material may not be strong enough, causing the optical fiber core to protrude or the bundle material to break. On the other hand, the bundle materials described in Patent Documents 2 and 4 are applied to single-bunching systems, but because the width of the bundle material is narrow, the binding of the bundle material to the optical fiber core is strong, which tends to increase transmission loss, and further performance improvements are needed.

[0008] Therefore, the present invention aims to provide an optical fiber core bundle tape suitable for bundled optical fiber cores using a single bunching method in which the tape is wrapped spirally around an optical fiber core bundle, and an optical fiber unit formed using this bundled tape. [Means for solving the problem]

[0009] The optical fiber core bundling tape according to the present invention is wound spirally around an optical fiber core bundle in a single piece. The cross section perpendicular to the longitudinal direction has a sea-island structure in which multiple island components made of a second thermoplastic resin having a melting point 20°C or more higher than that of the first thermoplastic resin are scattered within a sea component made of a first thermoplastic resin. The tape has a width of 3.2 to 5.0 mm, a thickness of 0.12 mm or less, a tensile elongation of 20 to 50%, and a thermal shrinkage rate of 1.1 to 1.5% when heated at 100°C for 3 hours. This optical fiber core bundling tape can achieve a thermal shrinkage rate of 0.25 to 0.5% when heated at 80°C for 6 hours, for example. The optical fiber core bundling tape of the present invention may be formed by bundling multiple composite fibers having a sheath-core structure in which the sheath portion is made of a first thermoplastic resin and the core portion is made of a second thermoplastic resin, and fusing the sheath portions of each composite fiber into a single unit. In this case, the total fineness can be 3000 to 5000 dTex, and the number of filaments of the composite fiber can be 50 to 500. For the first thermoplastic resin in the optical fiber core bundling tape of the present invention, for example, a thermoplastic resin with a melting point of 100 to 260°C can be used.

[0010] The optical fiber unit according to the present invention has one optical fiber core bundling tape, as described above, spirally wrapped around the outer circumference of an optical fiber core bundle, which is made up of multiple optical fiber cores. [Effects of the Invention]

[0011] According to the present invention, it is possible to realize an optical fiber core bundleing tape suitable for bundleing using a single-bunching method, and an optical fiber unit that can achieve stable performance even with a single-bunching method. [Brief explanation of the drawing]

[0012] [Figure 1] This figure schematically shows the cross-sectional structure of the optical fiber core bundling tape according to the first embodiment of the present invention. [Figure 2] This is a schematic perspective view showing a sheath-core composite fiber bundle before fusion. [Figure 3] This is a schematic perspective view showing an example configuration of an optical fiber unit according to a second embodiment of the present invention. [Modes for carrying out the invention]

[0013] The embodiments for carrying out the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described below.

[0014] (First Embodiment) First, the optical fiber core bundle tape (hereinafter simply referred to as "bunching tape") according to the first embodiment of the present invention will be described. The bundle tape of this embodiment is used for bundles using a single bunching method and is wound spirally around an optical fiber core bundle as a single piece when manufacturing an optical fiber unit.

[0015] [Tape Configuration] Figure 1 is a schematic diagram showing the cross-sectional structure of the bonding tape of this embodiment. As shown in Figure 1, the bonding tape 1 of this embodiment has a sea-island structure in which a cross section perpendicular to the longitudinal direction contains a sea component 11 made of a first thermoplastic resin, with a plurality of island components 12 made of a second thermoplastic resin having a melting point 20°C or more higher than that of the first thermoplastic resin.

[0016] The first thermoplastic resin forming the sea component 11 is not particularly limited and may be any of a single thermoplastic resin, a copolymerized thermoplastic resin, and various modified thermoplastic resins. However, from the viewpoints of improving spinning stability and production stability during tape formation, those having a melting point in the range of 100 to 260°C are preferred. Also, from the viewpoints of improving spinning stability and tape physical properties, polyolefin-based resins are preferred.

[0017] Specifically, the first thermoplastic resin forming the sea component 11 includes ethylene polymers such as high-density, medium-density, or low-density polyethylene and linear low-density polyethylene, copolymers of propylene and other α-olefins such as propylene-butene-1 random copolymer and propylene-ethylene-butene-1 random copolymer, amorphous propylene-based polymers such as soft polypropylene, and poly-4-methylpentene-1. These thermoplastic resins may be used alone or in combination of two or more.

[0018] The second thermoplastic resin forming the island component 12 is not particularly limited as long as its melting point is 20°C or higher than that of the first thermoplastic resin described above and it is capable of melt spinning. Specifically, crystalline polypropylene, crystalline polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamide (nylon), and aromatic polyester resins (liquid crystal polymers) can be used. Among these resins, from the viewpoint of improving spinnability, crystalline polypropylene, polyethylene terephthalate, and polyamide are preferred. Note that the thermoplastic resins described above may be used alone or in combination of two or more.

[0019] The above-mentioned first and second thermoplastic resins may be colored, and weathering agents, heat-resistant agents, etc. may be added. Furthermore, other additives can be added as necessary within a range that does not inhibit the effects of the present invention. Examples of other additives added to the thermoplastic resin include, for example, processing heat stabilizers, light stabilizers, ultraviolet absorbers, antioxidants, lubricants, colorants, antistatic agents, flame retardants, water repellents, waterproof agents, hydrophilicity-imparting agents, conductivity-imparting agents, heat conductivity-imparting agents, electromagnetic wave shielding property-imparting agents, light transmittance adjusters, fluorescent agents, sliding property-imparting agents, transparency-imparting agents, antiblocking agents, metal deactivators, and antibacterial agents, etc.

[0020] The above-mentioned binding tape 1 can be manufactured from a sheath-core structured composite fiber. FIG. 2 is a perspective view schematically showing a sheath-core composite fiber bundle before fusion. As shown in FIG. 2, the composite fiber 2 processed into the binding tape 1 has a sheath portion 21 made of the above-mentioned first thermoplastic resin and a core portion 22 made of the above-mentioned second thermoplastic resin. Then, a plurality of such sheath-core structured composite fibers 2 are bundled, and the sheath portions 21 are fused and integrated to obtain the binding tape 1.

[0021] The composite fiber 2 constituting the binding tape 1 preferably has a total fineness of 3000 to 5000 dTex and a number of filaments of 50 to 500. Thereby, a binding tape 1 with good flexibility and without excessive side pressure being applied to the optical fiber core bundle can be obtained.

[0022] [Tape width w] When binding an optical fiber core bundle by the single-bunching method, if the tape width w of the binding tape 1 is less than 3.2 mm, the tape strength is insufficient, and the optical fiber core may protrude or the tape may break. On the other hand, if the tape width w of the binding tape 1 exceeds 5.0 mm, the followability with respect to the optical fiber core bundle decreases. Therefore, in the binding tape 1 of the present embodiment, the tape width w is set to 3.2 to 5.0 mm.

[0023] [Tape thickness t] If the tape thickness t of the bundling tape 1 exceeds 0.12 mm, handling during bundling may be reduced. Therefore, in the bundling tape 1 of this embodiment, the tape thickness t is set to 0.12 mm or less.

[0024] [Tensile elongation] If the tensile elongation of the bonding tape 1 is less than 20%, breakage or cracking may occur in the tape when bonding the optical fiber cores, leading to poor quality of the manufactured optical fiber units. Furthermore, if the tensile elongation of the bonding tape 1 exceeds 50%, the tape stretches when bonding the optical fiber cores, reducing processability. Therefore, in this embodiment, the tensile elongation of the bonding tape 1 is set to a range of 20-50%.

[0025] The tensile elongation of the bonding tape 1 in this embodiment can be measured by conventionally known methods. For example, when measuring with the Tensilon universal material tester RTG-1210 manufactured by A&D Company, Limited, the measurement can be performed under conditions of a chuck distance of 200 mm and a tensile speed of 500 mm / min.

[0026] [Thermal shrinkage rate] The optical fiber core bundling tape 1 of this embodiment has a thermal shrinkage rate of 1.1 to 1.5% when heated at 100°C for 3 hours. If the thermal shrinkage rate when heated at 100°C for 3 hours is less than 1.1%, the holding power of the optical fiber cores after bundling will be weak. On the other hand, if the thermal shrinkage rate when heated at 100°C for 3 hours exceeds 1.5%, the heat will tighten the optical fiber cores when forming the outermost sheath in the optical cable manufacturing process, increasing transmission loss. Therefore, by setting the thermal shrinkage rate of the bundling tape of this embodiment to 1.1 to 1.5% when heated at 100°C for 3 hours, it is possible to realize an optical fiber unit with low transmission loss and high holding power of the optical fiber cores.

[0027] Furthermore, the bonding tape 1 of this embodiment preferably has a thermal shrinkage rate of 0.25 to 0.5% when heated at 80°C for 6 hours. By setting the thermal shrinkage rate within this range when heated at 80°C for 6 hours, an optical fiber unit with low transmission loss and high retention force of the optical cable core can be obtained.

[0028] The heat shrinkage rate of the conjugation tape 1 can be measured by the following method. First, a 2m sample is cut from the conjugation fiber to be measured, and markings are accurately made at 1m intervals as the inspection length. The load used during marking is precisely defined to the inspection length and is standardized to a load equivalent to 0.0393 cN / dtex, which does not stretch the fiber. Then, the test piece is placed in a dry heat oven heated to 100°C or 80°C without load and subjected to a heat treatment for 3 or 6 hours until the heat shrinkage rate reaches saturation. Then, while applying a load of 0.0393 cN / dtex to the test piece, taking care not to twist it, the length of the marked area is measured, and the percentage change in the inspection length before and after the heat treatment is calculated as the heat shrinkage rate (%).

[0029] As detailed above, the binding tape of this embodiment has a wider width than conventional products, a tensile elongation of 20-50%, and a heat shrinkage rate of 1.1-1.5% when heated at 100°C for 3 hours. This improves processability and reduces the likelihood of cracking or breaking of the tape during the binding process. As a result, the occurrence of quality defects is suppressed when the tapes are unitized, and a binding tape suitable for single-bunching binding can be realized.

[0030] (Second embodiment) Next, a second embodiment of the optical fiber unit of the present invention will be described. Figure 3 is a schematic perspective view showing an example of the configuration of the optical fiber unit of this embodiment. As shown in Figure 3, in the optical fiber unit 30 of this embodiment, one optical fiber bundle tape 1 of the first embodiment is wrapped around the outer circumference of an optical fiber bundle in which a plurality of optical fiber cores 3 are bundled together.

[0031] In this embodiment, the optical fiber unit uses an optical fiber core bundlening tape 1 with excellent processability, making it less likely for the tape to crack or break during the bundlening process, thus suppressing the occurrence of quality defects. Furthermore, in this embodiment, the bundlening tape 1 is wrapped using a single bunching method, and since the tapes do not cross each other, the problem of thickness at intersections does not occur, and stable performance can be obtained.

[0032] The optical fiber core wire 3 used in the optical fiber unit of this embodiment includes not only optical fiber strands, but also optical fiber dyed wires having a colored layer on the outside of the optical fiber strands, optical fiber tapes made by bundling multiple optical fiber dyed wires together and forming them into a tape shape with a tape layer, and intermittently fixed tape core wires in which single optical fiber strands are intermittently bonded.

[0033] As detailed above, the optical fiber unit of this embodiment uses a bundled tape with improved strength and handling properties, and bundles optical fiber cores using a single-bunching method, resulting in low transmission loss and high retention force of the optical cable cores. As a result, it is possible to realize an optical fiber unit with good quality and stable performance. [Examples]

[0034] The effects of the present invention will be specifically described below with reference to examples and comparative examples. In this example, the bonding tapes of the example and comparative example were manufactured by the method shown below, and their processability was evaluated.

[0035] <Preparation of conjugation tape> A sheath-core composite fiber was formed using ethylene-polypropylene random copolymer (CoPP), which has a melting point of 134°C, as the sheath component, and polyethylene terephthalate (PET), which has a melting point of 256°C, as the core component. From this composite fiber (single fiber), a tape-like sea-island type fiber (conjugation tape) of a predetermined width was produced.

[0036] <Tape width and thickness> Using a microtome, a sample with a cross-section perpendicular to the longitudinal direction was cut from the conjugation tape. This tape cross-section sample was fixed to a horizontal sample stage and observed from directly above and to the side using a KEYENCE digital microscope (VHX-900), and photographed with a camera fitted with an appropriate magnifying lens. Next, the captured images were imported into a computer, and the length was measured by comparing the length of an arbitrary point with a reference length. The major axis was used as the tape width and the minor axis as the tape thickness, and these dimensions were determined.

[0037] In this process, the tape width was measured with an accuracy of 1 / 10 mm using images taken with a 50x magnifying lens. The tape thickness was measured with an accuracy of 1 / 100 mm using images taken with a 175x magnifying lens. The dimensions of each part were measured five times at 1m intervals, and the average value was calculated.

[0038] <Tensile elongation> The tensile elongation of each bonding tape in the examples and comparative examples was calculated using the following formula 1 after fracture testing with the Tensilon universal material testing machine RTG-1210 manufactured by A&D Company, Limited. The distance L0 between the chucks before measurement was set to 200 mm, the tensile speed to 500 mm / min, and the distance L between the chucks at fracture was measured.

[0039]

number

[0040] <Thermal shrinkage rate> The heat shrinkage rate at 100°C was measured by curing a 1000mm length of tape in an oven heated to 100°C for 3 hours, then removing it and measuring its length T (mm). The heat shrinkage rate at 80°C was measured by curing a 1000mm length of tape in an oven heated to 80°C for 6 hours, then removing it and measuring its length T (mm). The heat shrinkage rate was then calculated using the following formula 2.

[0041]

number

[0042] <Evaluation of processability> The processability of each bonding tape in the examples and comparative examples was evaluated by winding one bonding tape around an 8mm diameter nylon tube five times in the S direction at 80mm intervals, and visually checking whether "breakage," "cracking," or "slack" occurred in the optical fiber core bonding tape. Here, "cracking" refers to a state in which a crack has occurred in the wound portion that penetrates in the thickness direction and extends 3mm or more in the longitudinal direction. "Slack" refers to a state in which a gap of 1.5mm or more has occurred between the wound portion and the nylon tube.

[0043] As a result, tapes that showed no "breakage," "cracking," or "loosening" were classified as having good processability (○), while tapes that showed even one instance of "breakage," "cracking," or "loosening" were classified as having poor processability (×). The results are shown in Tables 1 and 2 below.

[0044] [Table 1]

[0045] [Table 2]

[0046] As shown in Table 2, the bundling tapes of Comparative Examples 1 to 3 had widths of 1.20 to 2.80 mm, which is narrower than the range of the present invention, resulting in fracture. On the other hand, the bundling tape of Comparative Example 4 had a width exceeding 5.0 mm and a tensile elongation of less than 20%, resulting in reduced conformability and cracking. The bundling tape of Comparative Example 5 had a thickness exceeding 0.12 mm, which is thicker than the range of the present invention, resulting in reduced conformability and cracking. The bundling tape of Comparative Example 6 had a tensile elongation exceeding 50%, resulting in sagging.

[0047] The bonding tape in Comparative Example 7 had a thermal shrinkage rate of less than 1.1% after heating at 100°C for 3 hours, resulting in weak holding power and sagging. On the other hand, the tape in Comparative Example 8 had a thermal shrinkage rate exceeding 1.5% after heating at 100°C for 3 hours, causing deformation of the nylon tube due to shrinkage, raising concerns about increased transmission loss when applied to optical fiber cables.

[0048] In contrast, the bonding tapes of Examples 1 to 4, which were manufactured within the scope of the present invention, did not exhibit "breakage," "cracking," or "sagging," and had good processability.

[0049] From the above results, it has been confirmed that the present invention makes it possible to realize a conjugation tape suitable for conjugation using a single-bunching method.

[0050] Furthermore, the present invention may also take the following forms. [1] A fiber optic core bundle tape that is wrapped spirally around a bundle of fiber optic cores, A cross-section perpendicular to the longitudinal direction has a sea-island structure in which multiple island components made of a second thermoplastic resin having a melting point 20°C or more higher than that of the first thermoplastic resin are scattered within a sea component made of a first thermoplastic resin. Width is 3.2~5.0mm, Thickness of 0.12 mm or less, Tensile elongation is 20-50%, The thermal shrinkage rate when heated at 100°C for 3 hours is 1.1-1.5%. Tape for bundling optical fiber cores. [2] The optical fiber core bundling tape described in [1] has a thermal shrinkage rate of 0.25 to 0.5% when heated at 80°C for 6 hours. [3] Multiple composite fibers with a sheath-core structure, where the sheath portion is made of the first thermoplastic resin and the core portion is made of the second thermoplastic resin, are bundled together, and the sheath portions are fused together to form a single integrated structure. Total fiber density is 3000-5000 dTex. The number of filaments in the aforementioned composite fiber is 50 to 500. [1] or [2] Tape for bundling optical fiber cores as described above. [4] The first thermoplastic resin is a tape for bonding optical fiber cores according to any one of [1] to [3], wherein the melting point is 100 to 260°C. [5] An optical fiber unit in which one optical fiber core bundling tape described in any one of items [1] to [4] is spirally wrapped around the outer circumference of an optical fiber core bundle, which is made up of multiple optical fiber cores. [Explanation of Symbols]

[0051] 1. Conjugation tape 2 Composite Fibers 3 Optical fiber core 11 Marine components (first thermoplastic resin) 12 Island component (second thermoplastic resin) 21 Scabbard part 22 Core 30 Fiber Optic Units

Claims

1. A fiber optic core bundle tape that is wrapped spirally around a bundle of fiber optic cores, A cross-section perpendicular to the longitudinal direction has a sea-island structure in which multiple island components made of a second thermoplastic resin having a melting point 20°C or more higher than that of the first thermoplastic resin are scattered within a sea component made of a first thermoplastic resin. Width is 3.2 to 5.0 mm. Thickness of 0.12 mm or less, Tensile elongation is 20-50%. The thermal shrinkage rate when heated at 100°C for 3 hours is 1.1-1.5%. Tape for bundling optical fiber cores.

2. The optical fiber core bundling tape according to claim 1, wherein the thermal shrinkage rate when heated at 80°C for 6 hours is 0.25 to 0.5%.

3. Multiple composite fibers with a sheath-core structure, where the sheath portion is made of the first thermoplastic resin and the core portion is made of the second thermoplastic resin, are bundled together, and the sheath portions are fused together to form a single integrated structure. Total fiber thickness is 3000-5000 dTex. The number of filaments in the aforementioned composite fiber is 50 to 500. The optical fiber core bundling tape according to claim 1.

4. The optical fiber core bonding tape according to claim 1, wherein the first thermoplastic resin has a melting point of 100 to 260°C.

5. An optical fiber unit in which one optical fiber core bundling tape according to any one of claims 1 to 4 is spirally wrapped around the outer circumference of an optical fiber core bundle, which is made up of multiple optical fiber cores bundled together.

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