JP-7854750-B1 - Method for manufacturing conductive composite yarn

Abstract

[Problem] To provide a conductive composite yarn 2 that is less likely to cause false detections even 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: Includes the step of winding this sheath thread around a core thread formed from organic fibers to obtain a composite wire. [Selection Diagram] Figure 1

Inventors

• 金 龍煕

Assignees

• トクセン工業株式会社

Dates

Publication Date

20260507

Application Date

20250623

Claims (5)

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. A method for producing conductive composite yarn for woven fabrics, knitted fabrics, or sewn products, comprising the steps of: C: winding the above-mentioned sheath yarn around a core yarn formed from organic fibers to obtain a composite yarn ; and D: applying an overtwist to the above-mentioned composite yarn with an overtwist rate of 5% or more to remove torque, wherein the magnetic field is 0.40 mT or less and the torque is 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 wound around a core thread whose material is polyester.
4. In step C described above, the sheath thread is wound around the core thread to form a coil whose inner diameter Di is 1/4 or more of the wire diameter D2 of the sheath thread, as described in claim 1 or 2.
5. E: The manufacturing method according to claim 1 or 2, wherein a step of applying a finishing drawing to the sheath yarn, in which the reduction of surface area is 1% or more and 25% or less, while suppressing the martensitic transformation of the sheath yarn, is provided between step B and step C.

Description

This specification discloses a method for producing composite yarns containing conductive threads. As wearable devices requiring conductivity, woven or knitted fabrics containing conductive composite yarns are known. An example of a conductive composite yarn is disclosed in Japanese Patent Application Publication No. 2022-109899. This composite yarn contains organic fibers and metal fibers. The metal fibers contribute to the conductivity of this composite yarn. Japanese Patent Publication No. 2022-109899 Figure 1 is a front view showing a conductive composite yarn according to one embodiment.Figure 2 is an enlarged cross-sectional view along the line II-II in Figure 1.Figure 3 is a flowchart showing an example of a method for manufacturing the conductive composite yarn shown in Figure 1. The following describes preferred embodiments in detail, with reference to drawings as appropriate. 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. 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. Each sheath thread 6 may be a single strand or a stranded strand. The sheath thread 6 is formed from metal. Examples of preferred metallic elements to be included in the sheath thread 6 include iron, gold, silver, copper, platinum, zinc, tin, nickel, aluminum, tungsten, and molybdenum. Examples of 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 steel 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 types of sheath threads 6 made of different materials. The electrical resistance of the conductive composite yarn 2 is preferably 1 × 10⁻³ Ω/m or more and 1 × 10¹¹ Ω/m or less. 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. The original wire is then drawn (STEP 2). During drawing, 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. A drawing degree of 50% to 99% is preferable. If the original wire is made of austenitic stainless steel, the intermediate wire may have work-induced martensite produced by the drawing process. 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 between 850°C and 1150°C for at least 0.1 seconds. If the intermediate wire's microstructure contains martensite, this heat treatment may cause a transformation from martensite to austenite. The intermediate wire may undergo finishing drawing (STEP 4). In finishing drawing, the intermediate wire is passed through multiple dies. Finishing drawing yields the sheath yarn 6. The sheath yarn 6 is longer than the intermediate wire before finishing drawing. The sheath yarn 6 is thinner than the intermediate wire before finishing drawing. The reduction in surface area due to finishing drawing is preferably 1% to 25%, and particularly preferably 1% to 10%. Even if the intermediate wire is made of austenitic stainless steel, martensitic transformation due to finishing drawing hardly occurs. This manufacturing method may have a flow that does not include finishing drawing (STEP 4). The sheath yarn 6 is wound around the core yarn 4 (STEP 5). Suitable devices for this winding include a covering yarn twisting machine, a ring twisting machine, a double twister, a tubular twisting machine, and a buncher twisting machine. This winding forms a coil of sheath yarn 6. This winding yields a composite wire containing the core