braid

Abstract

To provide a braid of a CNT core yarn excellent in tensile strength and abrasion resistance.SOLUTION: A braid 100 has a core yarn 101 including a CNT yarn constituted of CNT (carbon nanotube), and a sheath yarn 102 covering the core yarn 101.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a ply yarn excellent in tensile strength and abrasion resistance.

Background Art

[0002] Conventionally, ply yarns having various characteristics have been provided according to uses and purposes.

[0003] For example, monofilaments of polyamide resins such as nylon 6 and nylon 6,6, fluororesins such as polyvinylidene fluoride, polyester resins such as polyethylene terephthalate, and polyolefin resins such as ultra-high molecular weight polyethylene are widely used as fishing lines according to target fish and fishing methods (see Patent Document 1).

[0004] Currently, a PE line, which is a multifilament made of polyethylene fibers, is popular as a fishing line. The PE line has advantages of being superior in tensile strength (linear strength) to the monofilaments made of the above synthetic resins, having a low elongation rate, and having a small cross-sectional area. On the other hand, the PE line is inferior in abrasion resistance (wear resistance) compared with these monofilaments.

[0005] As a material excellent in abrasion resistance, there is a CNT yarn in which carbon nanotubes (hereinafter referred to as CNT), which are one of carbon-based fine structures, are aggregated (see Patent Documents 2 to 4). However, the CNT yarn is inferior in tensile strength compared with the PE line.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] Conventionally, yarns having excellent properties in either tensile strength (linear strength) or abrasion resistance (wear resistance) have been developed. However, yarns having both tensile strength and abrasion resistance have not yet been developed. It is desired to provide a yarn having improved abrasion resistance while maintaining the excellent properties of a PE line widely used as a fishing line or the like.

[0008] The present invention is mainly for solving such problems, and an object thereof is to provide a ply yarn of a CNT core yarn excellent in tensile strength and abrasion resistance.

MEANS FOR SOLVING THE PROBLEMS

[0009] In one embodiment, the ply yarn has a core yarn including a CNT yarn which is a yarn made of CNT (carbon nanotube), and a sheath yarn covering the core yarn. In one embodiment, there is one core yarn and the sheath yarn is composed of a plurality of strands. In one embodiment, the sheath yarns have the same thickness and are made of the same material. In one embodiment, the sheath yarn contains polyethylene fibers.

EFFECTS OF THE INVENTION

[0010] According to the present invention, it is possible to provide a ply yarn of a CNT core yarn excellent in tensile strength and abrasion resistance.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0012] Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.

[0013] <Core yarn> The composite yarn according to an embodiment of the present invention has a core yarn containing a CNT yarn.

[0014] The CNT yarn is a yarn formed by aggregating CNTs. To form a CNT yarn from CNTs, when the generated CNTs are drawn out, a continuous body that is attracted to each other by the gravitational force between individual CNTs while being oriented in the drawn direction can be obtained, and by winding this, a CNT yarn can be obtained.

[0015] Individually, CNTs have a single-walled CNT (SWCNT) or a multi-walled CNT (MWCNT) in terms of their structure, and multi-walled CNTs with three or more layers are also known. Any of these CNTs can be used to form a CNT yarn.

[0016] The individual CNTs constituting the CNT yarn preferably have an average diameter of 3 to 15 nm, more preferably 7.5 to 15 nm. The length of the CNTs is preferably 50 μm or more, more preferably 100 μm or more. This is because if the average length of the CNTs is shorter than 50 μm, the number of ends of individual CNTs increases. The average diameter and average length of the CNTs are obtained by averaging the diameters and lengths of a plurality of arbitrarily selected CNTs using a transmission electron microscope.

[0017] The CNT yarn as an aggregate of individual CNTs has a diameter (wire diameter) of 20 μm to 70 μm, preferably 25 μm to 60 μm, more preferably 30 to 50 μm.

[0018] The length of the CNT yarn can be set to a preferable length according to the desired application. For example, when used as the core yarn of a combined yarn used as fishing line or the like, it can be, for example, 100 m to 300 m, but it can of course be shorter than 100 m, and if necessary, it can also be longer than 300 m.

[0019] The CNT yarn constituting the core yarn may be a single yarn formed by spinning a CNT web into a yarn shape, a bundle of multiple yarns, or a twisted bundle of multiple yarns. Preferably, the combined yarn according to the present invention uses a yarn in which a plurality of untwisted CNT yarns are bundled as the core yarn. Thereby, the tensile strength of the core yarn can be improved. The core yarn may be a bundle or twist of a CNT yarn and other fibers.

[0020] <Sheath yarn> The combined yarn according to the embodiment of the present invention has a sheath yarn containing fibers excellent in tensile strength such as UHMW-PE (ultra-high molecular weight polyethylene fiber).

[0021] The UHMW-PE used as the sheath yarn preferably has a thickness of 10 T to 440 T. Here, T: decitex is a unit representing the thickness of a fiber by the weight per a certain length. The thickness of a fiber with a weight of 1 g per 10,000 m in length is represented as 1 T (decitex).

[0022] The material of the sheath yarn may be a synthetic resin filament such as nylon or fluorocarbon in addition to UHMW-PE. In that case, the number and thickness of the sheath yarns are adjusted so as to ensure the required tensile strength and flexibility.

[0023] <Method for making a combined yarn> FIG. 1 is a schematic diagram showing the structure of a combined yarn 100 according to the embodiment of the present invention. To make the combined yarn 100, one or more UHMW-PEs are wound or woven around a core yarn 101 containing a CNT yarn as a sheath yarn 102.

[0024] The sheath yarn 102 may be spirally wound around the core yarn 101 by bundling one or more strands together, or may cover the core yarn 101 by knitting a plurality of strands. To increase the tensile strength of the combined yarn 100, it is more desirable to knit a plurality of strands rather than spirally winding the sheath yarn 102 around the core yarn 101.

[0025] When knitting a plurality of sheath yarns 102 around the core yarn 101, if the thickness and material of each sheath yarn 102 are made the same, it becomes easier to make the string and the contact between the core yarn 101 and the sheath yarn 102 becomes more stable. Also, the more the number of sheath yarns 102, the fewer the irregularities on the outer peripheral surface of the combined yarn 100 and the smoother it becomes, and since the core yarn 101 is tightened from various directions and the core yarn 101 contracts uniformly, the balance between tensile strength and abrasion resistance is excellent. The number of sheath yarns 102 is preferably 3 or more from the viewpoint of ensuring tensile strength, 7 or more from the viewpoint of ensuring abrasion resistance, and 24 or less from the viewpoint of ensuring flexibility. Note that by making the thickness of one or more sheath yarns 102 different from that of the other sheath yarns 102, it is also possible to change the way the combined yarn 100 bends. Or, by making the material of one or more sheath yarns 102 different from that of the other sheath yarns 102, it is also possible to appropriately change the characteristics of the combined yarn 100.

[0026] <Evaluation of Tensile Strength> To evaluate the tensile strength of the combined yarn according to the present invention, the tensile strengths of two examples (Example 1, Example 2) with the core yarn being a CNT yarn and the sheath yarn being UHMW-PE (hereinafter referred to as PE material) and two comparative examples (Comparative Example 1, Comparative Example 2) with the core yarn being a PE material and the sheath yarn being a PE material were measured and compared.

[0027] Table 1 is a table showing the thickness of the combined yarns according to Examples 1 and 2 and Comparative Examples 1 and 2 and the ratio of the cross-sectional area of the core yarn to the cross-sectional area of the combined yarn. Both Example 1 and Comparative Example 1 were set so that the thickness of the combined yarn was 0.20 mm (equivalent to size 1) and the ratio of the cross-sectional area of the core yarn to the cross-sectional area of the combined yarn was 38%. Both Example 2 and Comparative Example 2 were set so that the thickness of the combined yarn was 0.12 mm (equivalent to size 0.7) and the ratio of the cross-sectional area of the core yarn to the cross-sectional area of the combined yarn was 60%.

Table 1

[0028] Table 2 shows a table indicating the breaking load, breaking load ratio, breaking load per unit cross-sectional area, and breaking load ratio per unit cross-sectional area when a tensile load is applied in the longitudinal direction of these ply yarns. Here, the breaking load ratio is the ratio of the breaking load when the breaking load of Comparative Example 2 is taken as 1. The breaking load ratio per unit cross-sectional area is the ratio of the breaking load per unit cross-sectional area when the breaking load per unit cross-sectional area of Comparative Example 1 is taken as 1.

Table 2

[0029] Figure 2 is a graph plotting the breaking load ratio. It can be seen that Example 1 with the core yarn being a CNT yarn has a larger breaking load ratio compared to Comparative Example 1 under the same conditions (same thickness, same ratio of the cross-sectional area of the core yarn to the cross-sectional area of the ply yarn) where the core yarn is PE. Similarly, Example 2 has a larger breaking load ratio compared to Comparative Example 2 under the same conditions.

[0030] Figure 3 is a graph plotting the breaking load ratio per unit cross-sectional area. It can be seen that the groups of Examples 1 and 2 with the core yarn being a CNT yarn have a larger breaking load ratio per unit cross-sectional area compared to the groups of Comparative Examples 1 and 2 where the core yarn is PE.

[0031] Therefore, it can be evaluated that the ply yarn with the core yarn being a CNT yarn is superior in tensile strength to the ply yarn with the core yarn being a PE material.

[0032] <Evaluation of Abrasion Resistance> To evaluate the abrasion resistance of the ply yarn according to the present invention, the abrasion resistance of an example with the core yarn being a CNT yarn and the sheath yarn being a PE material and a comparative example with the core yarn being a PE material and the sheath yarn being a PE material was measured and compared by the following method. Also, for reference, the abrasion resistance of a commercially available multifilament PE line, a monofilament nylon line, and a fluorocarbon line was measured by the same method.

[0033] The specific measurement method will be described with reference to Fig. 4. In Fig. 4, 1 is a reciprocating body such as a piston or a cylinder (stroke length: 10 mm), 2 is a load (weight: 75 g), 3 is a twisted yarn, and 4 is a friction body (sandpaper #240). The twisted yarn 3 with one end fixed to the reciprocating body 1 and the other end fixed to the weight 2 was placed on the friction body 4, and the reciprocating motion was repeated at regular time intervals, and the number of breakages was measured.

[0034] Table 3 is a table showing the yarn thicknesses according to the examples, comparative examples, and reference examples. In both Example 1 and Comparative Example 1, the thickness of the twisted yarn was set to 0.20 mm, and the ratio of the cross-sectional area of the core yarn to the cross-sectional area of the twisted yarn was set to 38%. As Reference Examples 1 to 3, a PE line, a nylon line, and a fluorocarbon line (all commercially available products) with a yarn thickness of approximately 0.20 mm were prepared.

Table 3

[0035] Table 4 is a table showing the number of durability cycles (number of breakages) and the durability cycle ratio when these yarns are rubbed by the method shown in Fig. 4. Here, the durability cycle ratio is the ratio of the number of breakages when the number of breakages in Comparative Example 1 is set to 1.

Table 4

[0036] Fig. 5 is a graph plotting the durability cycle ratio. Example 1 with the core yarn being CNT yarn had 11.9 times the number of durability cycles compared to Comparative Example 1 under the same conditions (same thickness, same ratio of the cross-sectional area of the core yarn to the cross-sectional area of the twisted yarn) with the core yarn being PE. Note that Reference Example 1 (PE line size 1.0) had 1.9 times the number of durability cycles of Comparative Example 1, Reference Example 2 (nylon line size 1.5) had 6.7 times the number of durability cycles of Comparative Example 1, and Reference Example 3 (fluorocarbon line size 1.5) had 8.6 times the number of durability cycles of Comparative Example 1. Here, the reason why the number of durability cycles of Reference Example 1 (PE line size 1.0) slightly exceeded that of Comparative Example 1 which also used only PE material is considered to be that in commercially available Reference Example 1, techniques for twisting and coating were fully utilized to improve the durability of the PE line.

[0037] Therefore, it can be evaluated that the combined yarn with the core yarn being a CNT yarn is overwhelmingly superior in abrasion resistance to the combined yarn with the core yarn being a PE material. In addition, even when compared with the monofilament lines of Reference Examples 2 and 3, which are generally said to have excellent abrasion resistance, the combined yarn with the core yarn being a CNT yarn showed extremely excellent abrasion resistance.

[0038] The reason is considered as follows. The CNT yarn is bonded by intermolecular forces. Therefore, although the CNTs on the outer peripheral side of the core yarn come off from the CNT yarn due to friction, since the CNTs are bonded by intermolecular forces, fluff is gradually formed on the outer periphery of the core yarn. It is assumed that this fluff of CNTs serves as a coating that reduces the friction of the CNTs inside the core yarn.

[0039] According to the present embodiment, the combined yarn with the CNT yarn as the core yarn and the PE material as the sheath yarn has excellent tensile strength compared to the combined yarn with the PE material as the core yarn. In addition, it has overwhelmingly excellent abrasion resistance compared to the combined yarn with the PE material as the core yarn.

[0040] It should be noted that within the scope of the present invention, free combinations of each embodiment, or modifications of any component of each embodiment, or omissions of any component in each embodiment are possible.

[0041] For example, in the above-described embodiment, the fishing line was mainly shown as the use of the combined yarn according to the present invention, but the present invention is not limited thereto, and it is applicable to various uses that require both tensile strength and abrasion resistance. For example, by using it as a textile fiber, the present invention can be applied to clothes and protective gear, parts or members of vehicles, ships, and aircraft, building and civil engineering materials, parachutes, tents, sails, and interior decoration items including curtains and wall hangings, which are excellent in tensile strength and abrasion resistance. In addition, by twisting or combining one or a plurality of combined yarns, the present invention can be applied to sports goods including nets, ropes, fishing nets, octopus lines, fishing tackle, and racket guts, wires, etc.

[0042] In addition, in the above-described embodiments, an example in which a PE material is adopted as the material of the sheath yarn has been mainly shown. However, the present invention is not limited thereto, and other materials may be used for the sheath yarn. At this time, since it is considered that the tensile strength of the ply yarn mainly depends on the sheath yarn, it is preferable to use a material having excellent tensile strength for the sheath yarn. In addition, since it is considered that the abrasion resistance of the ply yarn is a characteristic mainly ensured by the core material of the CNT yarn, it is considered that even if a material other than the PE material is used for the sheath yarn, it still exhibits overwhelming abrasion resistance.

Explanation of Signs

[0043] 100 Ply yarn 101 Core yarn 102 Sheath yarn 1 Reciprocating body 2 Load 3 Ply yarn 4 Friction body

Claims

1. A core yarn containing a CNT yarn which is a yarn composed of CNTs (carbon nanotubes), and a sheath yarn covering the core yarn, a ply yarn.

2. The core yarn is a single one, and the sheath yarn is composed of a plurality of yarns, The ply yarn according to Claim 1.

3. The plurality of sheath yarns have the same thickness and are made of the same material, The ply yarn according to Claim 2.

4. The sheath yarn contains polyethylene fibers, The ply yarn according to Claim 1.

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