Method for manufacturing conductive composite yarn

Abstract

To provide conductive composite yarn 2 that is less likely to cause false detections when textile products are inspected with a metal detector. [Solution] The conductive composite yarn 2 has a core yarn 4 and three sheath yarns 6. Each sheath yarn 6 is wound around the core yarn 4 at a predetermined pitch. These sheath yarns 6 have a spiral shape. The core yarn 4 is made of organic fibers. The sheath yarns 6 are made of metal. The method for manufacturing this conductive composite yarn 2 is as follows: A: The process of drawing a raw wire, which is made of metal, to obtain an intermediate wire. B: The process of applying heat treatment to this intermediate line to obtain the sheath thread, and C: A process of winding this sheath thread around a core thread made of organic fibers to obtain a composite wire. Includes.

Description

Technical Field

[0001] This specification discloses a method for manufacturing a composite yarn containing a conductive yarn.

Background Art

[0002] As a wearable device that requires conductivity, a knitted or woven fabric containing a conductive composite yarn is known. An example of a conductive composite yarn is disclosed in Japanese Patent Application Laid-Open No. 2022-109899. This composite yarn contains an organic fiber and a metal fiber. The metal fiber contributes to the conductivity of this composite yarn.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a fiber product containing the conductive composite yarn disclosed in Japanese Patent Application Laid-Open No. 2022-109899 is inspected with a metal detector, false detection is likely to occur due to the metal fiber.

[0005] What the applicant intends is to provide a conductive composite yarn in which false detection is unlikely to occur even when the fiber product is inspected with a metal detector.

Means for Solving the Problems

[0006] The method for manufacturing a conductive composite yarn disclosed in this specification is A: A step of drawing a raw wire made of metal to obtain an intermediate wire, B: A step of heat-treating the intermediate wire to obtain a sheath yarn, and C: A step of winding the sheath yarn around a core yarn formed from an organic fiber to obtain a composite yarn including.

Effects of the Invention

[0007] This composite yarn is conductive. When textile products containing this conductive composite yarn are inspected using a metal detector, false detections are less likely. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a front view showing a conductive composite yarn according to one embodiment. [Figure 2] Figure 2 is an enlarged cross-sectional view along the line II-II in Figure 1. [Figure 3] Figure 3 is a flowchart showing an example of a method for manufacturing the conductive composite yarn shown in Figure 1. [Modes for carrying out the invention]

[0009] Preferred embodiments will be described in detail below, with reference to drawings as appropriate.

[0010] Figures 1 and 2 show a conductive composite yarn 2. This conductive composite yarn 2 has a core yarn 4 and three sheath yarns 6. Each sheath yarn 6 is wound around the core yarn 4 at a predetermined pitch. The sheath yarns 6 have a spiral shape. Each sheath yarn 6 is in contact with an adjacent sheath yarn 6.

[0011] The core yarn 4 may be a spun yarn or a multifilament. The core yarn 4 is formed from a number of organic fibers. Suitable organic fibers for the core yarn 4 include natural fibers, synthetic fibers, and regenerated fibers. Examples of natural fibers include cotton, linen, wool, and silk. Examples of synthetic fibers include polyester fibers, nylon fibers, acrylic fibers, polyolefin fibers, para-aramid fibers, meta-aramid fibers, polyarylate fibers, and polybenzoxazole fibers. An example of a regenerated fiber is rayon. From the viewpoint of versatility, polyester fibers are particularly preferred organic fibers.

[0012] Each sheath thread 6 may be a single strand or a stranded strand. The sheath thread 6 is formed from a metal. Preferred metallic elements to be included in the sheath thread 6 include iron, gold, silver, copper, platinum, zinc, tin, nickel, aluminum, tungsten, and molybdenum. Preferred materials for the sheath thread 6 include steel, copper, copper alloys, and aluminum alloys. Stainless steel is more preferred, and austenitic stainless steel is particularly preferred. Examples of versatile austenitic stainless steels include SUS304, SUS316, and SUS316L. The conductivity of the composite yarn 2 is achieved by this sheath thread 6. Since the composite yarn 2 is conductive, woven, knitted, and sewn products containing this composite yarn 2 are suitable for wearable devices. The conductive composite yarn 2 may have two or more sheath threads 6 made of different materials. The electrical resistance of the conductive composite yarn 2 is 1 × 10⁻⁶. -3 Ω / m or more 1×10 11 Ω / m or less is preferable.

[0013] Figure 3 shows an example of a manufacturing method for conductive composite yarn 2. In this manufacturing process, a base wire for the sheath yarn 6 is prepared (STEP 1). A typical material for the base wire is austenitic stainless steel. SUS304 is an example of this austenitic stainless steel.

[0014] The original wire is then drawn (STEP 2). In the drawing process, the original wire is passed through multiple dies. Drawing yields an intermediate wire. The intermediate wire is longer than the original wire. The intermediate wire is thinner than the original wire. The degree of processing by drawing is preferably between 50% and 99%. If the material of the original wire is austenitic stainless steel, the microstructure of the intermediate wire may contain work-induced martensite produced by drawing.

[0015] This intermediate wire is subjected to heat treatment (STEP 3). A typical heat treatment is annealing. In this heat treatment, the intermediate wire is exposed to a temperature of 850°C to 1150°C for a period of 0.1 seconds or more. If the metal structure of the intermediate wire contains martensite, this heat treatment may cause a transformation from martensite to austenite.

[0016] A finish drawing may be applied to this intermediate wire (STEP4). In the finish drawing, the intermediate wire is passed through a plurality of dies. By the finish drawing, the sheath yarn 6 is obtained. The sheath yarn 6 is longer than the intermediate wire before the finish drawing. The sheath yarn 6 is thinner than the intermediate wire before the finish drawing. The area reduction rate by the finish drawing is preferably 1% or more and 25% or less, and particularly preferably 1% or more and 10% or less. Even if the material of the intermediate wire is austenitic stainless steel, martensite transformation hardly occurs due to the finish drawing. This manufacturing method may have a flow that does not include the finish drawing (STEP4).

[0017] This sheath yarn 6 is wound around the core yarn 4 (STEP5). Examples of the apparatus suitable for this winding include a covering yarn twister, a ring twister, a double twister, a tubular type twister, and a buncher type twister. By this winding, the sheath yarn 6 forms a coil. By this winding, a composite wire including the core yarn 4 and the sheath yarn 6 is obtained. The winding direction of the sheath yarn 6 is preferably different from the winding direction of the organic fiber in the core yarn 4. The winding direction of the sheath yarn 6 may coincide with the winding direction of the organic fiber in the core yarn 4.

[0018] Torque adjustment processing is performed on this composite wire (STEP6). By this torque adjustment processing, the torque remaining in the composite wire is removed, and the conductive composite yarn 2 shown in FIGS. 1 and 2 is obtained. Examples of preferable torque adjustment processing include overtwisting, roller correction, and tension application. Overtwisting is particularly preferable.

[0019] In overtwisting, the composite wire is stretched between two rollers. These rollers rotate. The direction of the axis of this rotation generally coincides with the traveling direction of the composite wire. By this rotation, the composite wire is overtwisted. When this twist is released, the residual torque is removed from the composite wire.

[0020] Preferable roller correction is performed by a plurality of roller pairs. Each roller pair has an upper roller and a lower roller. In the preferable correction processing, the composite wire is continuously fed in two perpendicular directions.

[0021] If winding (STEP 5) yields a composite wire that does not require torque removal, the manufacturing method may have a flow that does not involve straightening.

[0022] Since the sheath thread 6 undergoes heat treatment (STEP 3), its metallic structure contains austenite. The conductive composite thread 2 containing this sheath thread 6 has low magnetism. Typically, wearable devices are inspected for the presence of sewing needles using a needle detector. When a wearable device containing the conductive composite thread 2 with low magnetism is inspected, the needle detector is less likely to mistakenly identify the sheath thread 6 as a sewing needle. In other words, this conductive composite thread 2 suppresses false detection by the needle detector.

[0023] From the viewpoint of suppressing false detections, the magnetism of the conductive composite yarn 2 is preferably 0.40 mT or less, more preferably 0.20 mT or less, and particularly preferably 0.10 mT or less.

[0024] For the magnetic measurement, a reel made of synthetic resin with a diameter of 50 mm is prepared. Conductive composite yarn 2 is wound spirally around this reel. The pitch of this spiral is 0.2 mm. When the number of turns reaches 50, a first layer is formed with an axial distance of approximately 10 mm from the reel. When the number of turns reaches 50, the conductive composite yarn 2 is reversed and wound on top of the first layer at a pitch of 0.2 mm so as to form a spiral in the opposite direction to the spiral of the first layer. When the number of turns reaches 50, a second layer is formed with an axial distance of approximately 10 mm from the reel. The second layer is laminated on the first layer. Similarly, spiral winding and reversal are repeated until a laminate with 30 layers is obtained. A magnet with a magnetic field of 100 mT is brought into contact with the axial center of the surface of this laminate and held for 60 seconds. When the magnet is removed from the laminate, the magnetic field at the point where the magnet was in contact is measured using a Tesla meter. A typical Tesla meter is the "TM-701" from KANETEC.

[0025] Since the composite wire is subjected to torque adjustment processing (STEP 6), the torque of the conductive composite yarn 2 is small. When woven, knitted, or sewn products are manufactured from this conductive composite yarn 2, kinking is less likely to occur. Wearable devices containing this conductive composite yarn 2 have excellent appearance. From this viewpoint, a torque of 30 T / m or less is preferable, 26 T / m or less is more preferable, and 23 T / m or less is particularly preferable.

[0026] In torque measurement, a conductive composite yarn 2 is suspended in a U-shape with a sample length of 200 cm, and a hook is attached at a position 1 m from its lower end. A load of 0.0294 cN / dtex is applied to each of the two upper ends of the conductive composite yarn 2, and this load pulls the conductive composite yarn 2. In this state, the vicinity of these upper ends is fixed, and the load is released. A load of 0.00294 cN / dtex is then applied to the lower end of the conductive composite yarn 2. This causes the conductive composite yarn 2 to twist in the direction of the U-shape, and the conductive composite yarn 2 is twisted. The number of twists T in the conductive composite yarn 2 when this twisting stops is counted. The number of twists T per meter of conductive composite yarn 2 is the torque T / m.

[0027] If the torque adjustment process (STEP 6) results in overtwisting, a conductive composite yarn 2 with low torque can be obtained. From this viewpoint, the overtwist rate Po is preferably 5% or more, more preferably 8% or more, and particularly preferably 10% or more. An overtwist rate Po of 50% or less is preferred. The overtwist rate Po is calculated by the following formula. Po = (N2 - N1) / N1 * 100 In this formula, N1 is the number of twists in the composite wire before overtwisting (STEP 6) is performed, and N2 is the number of twists in the composite wire after it has been excessively twisted during overtwisting.

[0028] The fineness of the core yarn 4 is preferably 15 dtex or more and 500 dtex or less. Conductive composite yarn 2 with a fineness of 15 dtex or more has excellent durability. From this viewpoint, a fineness of 33 dtex or more is more preferable, and 56 dtex or more is particularly preferable. Woven, knitted, or sewn products with a good texture can be obtained from conductive composite yarn 2 with a fineness of 500 dtex or less. From this viewpoint, a fineness of 444 dtex or less is more preferable, and 390 dtex or less is particularly preferable.

[0029] From the viewpoint of achieving both conductivity and flexibility in the conductive composite yarn 2, the number N2 of the sheath yarns 6 is preferably between 2 and 6. As mentioned above, in this embodiment, this number N2 is 3.

[0030] In Figure 1, arrow P2 represents the winding pitch of the sheath yarn 6. This pitch P2 is preferably 0.50 mm or less. A woven or knitted fabric with a smooth surface can be obtained from a conductive composite yarn 2 having a pitch P2 of 0.50 mm or less. From this viewpoint, a pitch P2 of 0.40 mm or less is more preferable, and 0.30 mm or less is particularly preferable. From the viewpoint of ease of manufacture, a pitch of 0.05 mm or more is preferable.

[0031] In Figure 2, arrow Dc represents the wire diameter of the conductive composite yarn 2. The wire diameter Dc is preferably 0.07 mm or more and 0.40 mm or less. Conductive composite yarn 2 with a wire diameter Dc of 0.07 mm or more has excellent durability. From this viewpoint, a wire diameter Dc of 0.08 mm or more is more preferable, and 0.10 mm or more is particularly preferable. Conductive composite yarn 2 with a wire diameter Dc of 0.40 mm or less has excellent flexibility. From this viewpoint, a wire diameter Dc of 0.35 mm or less is more preferable, and 0.30 mm or less is particularly preferable.

[0032] In Figure 1, arrow D2 represents the wire diameter of the sheath thread 6. In Figure 2, arrow Di represents the inner diameter of the coil formed by the sheath thread 6. It is preferable that the inner diameter Di is 1 / 4 or more of the wire diameter D2. In this conductive composite thread 2, the coil distortion is small. The proportion of martensite in the metallic structure of this sheath thread 6 is small. From this viewpoint, it is particularly preferable that the inner diameter Di is 1 / 5 or more of the wire diameter D2.

[0033] This specification is also directed to a method for manufacturing wearable devices. This method yields a woven, knitted, or sewn product containing the conductive composite yarn 2 shown in Figures 1 and 2. Wearable devices obtained from this woven, knitted, or sewn product are less prone to false detection by needle detectors. [Examples]

[0034] The effects of the manufacturing method described in the following examples will be clarified, but the scope disclosed herein should not be interpreted as limiting based on the description of these examples.

[0035] [Example 1] A raw wire made of SUS304 with a diameter of 0.1 mm was subjected to solution treatment. This raw wire was drawn using multiple dies to obtain an intermediate wire with a diameter of 0.02 mm. The degree of completion in this drawing process was 96%. The breaking load of this intermediate wire was 0.82 N. This intermediate wire was heat-treated at 1000 °C for 1 second to obtain a sheath thread. The breaking load of this sheath thread was 0.25 N. A core thread (167dtex48f) made of polyester fiber was prepared. The breaking load of this core thread was 6.20 N. Three sheath threads were spirally wound onto this core thread at a pitch P2 of 0.30 mm using a tubular twisting machine to obtain a composite wire. This composite wire was overtwisted with an overtwist rate Po of 10% to obtain the conductive composite yarn according to Example 1. The structure of this conductive composite yarn is shown in Figures 1 and 2.

[0036] [Example 2] A composite yarn was obtained in the same manner as in Example 1, except that roller straightening was performed instead of over-twisting as a torque adjustment process.

[0037] [Example 3] A composite yarn was obtained in the same manner as in Example 1, except that a sheath yarn made of SUS316L with a breaking load of 0.16N was used.

[0038] [Comparative Example 1] A composite yarn was obtained in the same manner as in Example 1, except that the intermediate wire (breaking load: 0.82 N) after wire drawing was used as a sheath thread without heat treatment.

[0039] [Comparative Example 2] A composite yarn was obtained in the same manner as in Example 1, except that the intermediate wire (breaking load: 0.82 N) after wire drawing was used as a sheath thread without heat treatment and no straightening process was performed.

[0040] [Breakage during sewing] A seam was formed in the fabric using composite yarn. The breakage of the composite yarn during this process was evaluated. The results are shown in Table 1 below.

[0041] [Electrical resistance] The electrical resistance of the composite yarn was measured. This electrical resistance was 1 × 10⁻⁶. -3 Ω / m or more 1×10 11 Composite yarns with a density of Ω / m or less were considered "suitable." The results are shown in Table 1 below.

[0042] [Table 1]

[0043] As is clear from Table 1, the manufacturing methods of each example exhibit excellent performance in various aspects. The superiority of this manufacturing method is evident from these evaluation results.

[0044] [Disclosure items] Each of the following items discloses a preferred embodiment.

[0045] [Item 1] A: The process of drawing a raw wire, which is made of metal, to obtain an intermediate wire. B: A process of applying heat treatment to the above intermediate line to obtain a sheath thread, and C: A process of winding the above sheath thread onto a core thread made of organic fibers to obtain a composite wire. A method for manufacturing conductive composite yarn, comprising [a specific feature / feature].

[0046] [Item 2] D: Step to remove torque from the above composite line. The manufacturing method described in item 1, further comprising the above.

[0047] [Item 3] The manufacturing method described in item 2, wherein in step D above, the composite wire is subjected to overtwisting.

[0048] [Item 4] The manufacturing method described in item 3, wherein the overtwist rate in step D above is 5% or more.

[0049] [Item 5] The manufacturing method according to any one of items 1 to 4, wherein in step A above, a wire drawing process is performed on a raw wire whose material is stainless steel.

[0050] [Item 6] The manufacturing method according to any one of items 1 to 5, wherein the temperature of the heat treatment in step B is 850°C or higher and 1150°C or lower.

[0051] [Item 7] The manufacturing method according to any one of items 1 to 6, wherein in step C above, the sheath thread is wrapped around a core thread whose material is polyester.

[0052] [Item 8] The manufacturing method according to claim 1 or 2, wherein in step C above, the sheath thread is wound around the core thread to form a coil in which the inner diameter Di is 1 / 4 or more of the wire diameter D2 of the sheath thread.

[0053] [Item 9] E: Between process B and process C above, a process in which the sheath yarn is subjected to finishing drawing in which the reduction ratio is 45% or less. A manufacturing method according to any one of items 1 to 4, further comprising the above. [Industrial applicability]

[0054] The manufacturing method described above can yield conductive composite yarns suitable for various textile products. [Explanation of Symbols]

[0055] 2. Conductive composite yarn 4... Core thread 6...sheath thread

Claims

1. A: A process of drawing a raw wire whose material is SUS304 or SUS316L to obtain an intermediate wire. B: A process of heat-treating the above intermediate wire to induce a transformation into austenite, thereby reducing its magnetism and obtaining a sheath thread. C: A process of winding the above sheath thread onto a core thread made of organic fibers to obtain a composite wire. and D: A process of applying overtwist to the above composite wire, where the overtwist ratio is 5% or more, to remove torque. A method for manufacturing conductive composite yarn for woven fabrics, knitted fabrics, or sewn products, comprising a magnetic field of 0.40 mT or less and a torque of 30 T / m or less.

2. The manufacturing method according to claim 1, wherein the temperature of the heat treatment in step B is 850°C or higher and 1150°C or lower.

3. The manufacturing method according to claim 1 or 2, wherein in step C above, the sheath thread is wrapped around a core thread whose material is polyester.

4. The manufacturing method according to claim 1 or 2, wherein in step C above, the sheath thread is wound around the core thread to form a coil in which the inner diameter Di is 1 / 4 or more of the wire diameter D2 of the sheath thread.

5. E: A process of applying a finishing drawing to the sheath yarn, in which the reduction in surface area is 1% or more and 25% or less, while suppressing the martensitic transformation of the sheath yarn. The manufacturing method according to claim 1 or 2, wherein the above step B is provided between step C.

Images