Conductive fibers, clothing containing conductive fibers, and electrical and electronic equipment containing conductive fibers.

Abstract

The present invention provides: an electroconductive fiber that, in addition to high electroconductivity, electrical characteristic stability under deformation, etc., has superior flexibility and in particular is suitable for incorporating into a fabric such as a smart textile; and clothing or an electrical / electronic instrument in which said fiber is used. This electroconductive fiber has an average number of crimps of at least 2 / cm, has a metal layer on the fiber surface, and has a volume resistivity of 2 × 10-6 to 1 × 10-2 Ω∙cm, and furthermore has a total fineness of 10-1000 dtex.

Description

[Technical Field]

[0001] The present invention relates to conductive fibers that are particularly suitable for incorporation into fabrics such as smart textiles, and to clothing or electrical / electronic equipment using the same. [Background technology]

[0002] In recent years, there has been a growing demand for smart textiles, which incorporate various devices, sensors, IC chips, and other electronic components into knitted and woven fabrics. These smart textiles can be designed to suit a wide range of purposes, from sports to medical applications, and are therefore expected to be worn in various situations.

[0003] In smart textiles incorporating these electronic components, low-resistance electrical wiring is required for power transmission to drive the devices and for transmitting electrical signals from sensors. While ordinary copper wire provides sufficient conductivity for power transmission and signal transmission, it cannot adapt to the bending and stretching of the textile, resulting in an unnatural appearance when incorporated into clothing.

[0004] Against this backdrop, various technologies are being investigated to impart electrical stability and flexibility to conductive fibers against deformation. For example, stretchable conductive fibers (see Patent Document 1) have been developed in which a conductive layer made of copper iodide is formed near the interior surface of an elastomer-based stretchable fiber, and a technology (see Non-Patent Document 1) has been proposed in which conductive fibers are formed into a spring-like shape to impart high elasticity, thereby creating highly stretchable conductive wiring with excellent durability.

[0005] Furthermore, as a method for imparting conductivity to crimped synthetic fibers, a composite fiber has been proposed in which a conductive layer containing carbon black and a non-conductive layer having fiber-forming properties form a side-by-side or eccentric core-sheath composite, and the conductive layer forms at least a portion of the fiber surface (see Patent Document 2).

[0006] Separately, as a technology for imparting functionality to fibers by forming a metal layer, an electromagnetic wave shielding sheet (see Patent Document 3) has been proposed that includes a metal layer attached to the constituent fibers of a nonwoven fabric, and the nonwoven fabric includes crimped fibers and adhesive fiber solidification parts. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2010-209481 [Patent Document 2] Japanese Patent Publication No. 2009-46785 [Patent Document 3] Japanese Patent Publication No. 2020-17615 [Non-patent literature]

[0008] [Non-Patent Document 1] [online], February 25, 2015, National Institute of Advanced Industrial Science and Technology, accessed June 29, 2020, Internet<URL:https: / / www.aist.go.jp / aist_j / press_release / pr2015 / pr20150225 / pr20150225.html> [Overview of the project] [Problems that the invention aims to solve]

[0009] The technology described in Patent Document 1 states that conductive fibers with elasticity and electrical stability can be obtained by imparting conductivity to the sheath portion of a core-sheath composite fiber using two different types of elastomers. However, the technology in Patent Document 1 has the problem that, because elastomers are used, the fiber diameter of the resulting fibers becomes substantially thicker, and due to the elastic behavior unique to elastomers, a repulsive force is generated in the bent and stretched parts, causing discomfort when conductive fibers are incorporated into clothing.

[0010] The technology described in Non-Patent Document 1 states that conductive fibers with excellent elasticity and durability can be obtained by forming conductive fibers into a spring-like shape. However, the outer diameter of the spring-like fiber bundle is large, and the elastic behavior of the spring-like structure generates repulsive forces in the bent and stretched parts, which presents a problem of discomfort when conductive fibers are incorporated into clothing.

[0011] The technology described in Patent Document 2 states that a highly elastic conductive fiber can be obtained by using crimped fibers having a conductive layer containing carbon black. However, the volume resistivity of the obtained fiber is 1 × 10⁻⁶. -1 The resistance was high, exceeding Ω·cm, making it insufficient for use in power transmission or signal transmission from sensors. Furthermore, the conductivity was prone to large variations in resistance due to the dispersion of carbon black, making it difficult to ensure sufficient electrical stability.

[0012] Patent Document 3 proposes an electromagnetic shielding sheet in which a metal layer is attached to a nonwoven fabric. However, when this nonwoven fabric is cut and used for electrical wiring, it requires a larger conductive layer area compared to conductive fibers to obtain sufficient conductive performance, and because of its nonwoven fabric form, it is difficult to weave or knit into fabrics. For these reasons, it was unsuitable as electrical wiring for smart textiles.

[0013] Therefore, the object of the present invention, made in view of the above circumstances, is to provide a conductive fiber that has high conductivity and electrical stability against deformation, as well as excellent flexibility, and is particularly suitable for incorporation into fabrics such as smart textiles, and clothing or electrical / electronic equipment using the same. [Means for solving the problem]

[0014] Through further investigation, the inventors confirmed that, for conductive fibers used in smart textiles incorporating electronic components for power transmission and signal transmission from sensors, it is important that they possess not only high conductivity and stable electrical properties against deformation, but also excellent flexibility to follow the movement of the textile without causing discomfort.

[0015] Therefore, as a result of intensive studies to achieve the above performance, the present inventors have found that by disposing a metal layer on the surface of a fiber having a specific number of curls and setting the volume resistivity and the total fineness within specific ranges, in addition to deformation followability and electrical property stability, excellent flexibility that does not cause a sense of incongruity even when incorporated into textiles is exhibited, and the present invention has been completed.

[0016] The present invention aims to solve the above problems. The conductive fiber of the present invention has an average number of curls of 2 or more per cm, has a metal layer on the fiber surface, and has a volume resistivity of 2 × 10 -6 ~1 × 10 -2 Ω·cm, and further has a total fineness of 10 to 1000 dtex.

[0017] According to a preferred embodiment of the conductive fiber of the present invention, the average single fiber diameter is 5 to 20 μm.

[0018] According to a preferred embodiment of the conductive fiber of the present invention, it is composed of long fibers.

[0019] According to a preferred embodiment of the conductive fiber of the present invention, the volume resistivity when stretched by 10% in the fiber axis direction is 2 × 10 -6 ~1 × 10 -2 Ω·cm.

[0020] According to a preferred embodiment of the conductive fiber of the present invention, the shape of the curl is a three-dimensional coil shape.

[0021] In addition, the clothing or electric / electronic device of the present invention is at least partially composed of the above conductive fiber.

Advantages of the Invention

[0022] According to the present invention, in addition to high conductivity and electrical property stability against deformation, a conductive fiber having excellent flexibility, particularly suitable for incorporation into fabrics such as smart textiles, and a clothing or electric / electronic device using the same can be obtained.

Modes for Carrying Out the Invention

[0023] The conductive fiber of the present invention has an average crimp count of 2 or more, a metal layer on the fiber surface, and a volume resistivity of 2 × 10⁻⁶. -6 ~1 × 10 -2 It has a density of Ω·cm and a total fineness of 10 to 1000 dtex. The constituent elements will be described in detail below, but the present invention is not limited to the scope described below, unless it exceeds the gist of the invention.

[0024] [Sufficient fiber] In the present invention, it is preferable that the portion of the conductive fiber other than the metal layer is made of a thermoplastic polymer. Because the portion other than the metal layer is made of a thermoplastic polymer, it becomes easier to form the fiber shape using a melt spinning method, resulting in a conductive fiber with a uniform shape in the fiber axis direction.

[0025] Examples of thermoplastic polymers used in the conductive fibers of the present invention include polyester polymers and copolymers such as "polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate," aliphatic polyester polymers and copolymers such as "polylactic acid, polyethylene succinate, polybutylene succinate, polybutylene succinate adipate, polyhydroxybutyrate-polyhydroxyvalate copolymer, polycaprolactone," aliphatic polyamide polymers and copolymers such as "polyamide 6, polyamide 66, polyamide 610, polyamide 10, polyamide 12, polyamide 6-12," polyolefin polymers and copolymers such as "polypropylene, polyethylene, polybutene, polymethylpentene," water-insoluble ethylene-vinyl alcohol copolymer polymers containing 25 mol% to 70 mol% of ethylene units, and elastomer polymers such as polystyrene, polydiene, chlorine, polyolefin, polyester, polyurethane, polyamide, and fluorine. These can be selected and used from among these. Among these, polyester polymers and their copolymers are preferred because they allow for relatively easy formation of a metal layer by methods such as plating, and are less prone to peeling of the metal layer.

[0026] The conductive fibers of the present invention may contain various additives in the thermoplastic polymer, such as inorganic substances like titanium dioxide, silica, and barium oxide, carbon black, colorants such as dyes and pigments, flame retardants, fluorescent whitening agents, antioxidants, or ultraviolet absorbers, to the extent that they do not impair the effects of the present invention.

[0027] The conductive fibers of the present invention may be single-component fibers or composite fibers formed by combining two or more polymers. When the conductive fibers are composite fibers, examples include core-sheath type, sea-island type, side-by-side type, and eccentric core-sheath type, but the side-by-side type and eccentric core-sheath type are preferred, as these composite forms exhibit three-dimensional coil-like (helical) crimping in the fibers depending on the polymer combination. When the side-by-side type is used as the composite form, suitable examples of polymer combinations include combinations of the same type of polyester polymer with different viscosities, combinations of the same type of polyamide polymer with different viscosities, and combinations of different types of polyester polymers such as polyethylene terephthalate and polybutylene terephthalate. Furthermore, when the eccentric core-sheath type is used as the composite form, suitable examples of polymer combinations include, in addition to the examples of side-by-side type combinations mentioned above, combinations of polyester polymers and polyurethane polymers, and combinations of polyamide polymers and polyurethane polymers.

[0028] It is important that the conductive fibers of the present invention have an average crimp count of 2 or more. By increasing the average crimp count to 2 or more, preferably 3 or more, and more preferably 4 or more, the 10% modulus of the conductive fibers tends to decrease, thus improving flexibility. Furthermore, there is no particular upper limit to the average crimp count in the present invention, but approximately 60 or more is a practical upper limit.

[0029] The average crimp count in this invention is determined as follows. (1) Place a single fiber extracted from the multifilament onto a sample stage in an unloaded state, and take an image of a 1 cm portion of the single fiber using a microscope. (2) After counting the number of peaks and valleys of the fibers from the captured image, divide the total by 2 to find the crimp number. (3) The above measurement is performed five times for each level, changing the single fiber, and the arithmetic mean is taken as the average crimp count.

[0030] The crimped shape of the conductive fiber of the present invention can take a crimped shape such as a sawtooth shape, a three-dimensional coil shape, and combinations thereof, and among them, a three-dimensional coil shape is preferable. Since the crimped shape of the conductive fiber is a three-dimensional coil shape, the followability to stretching and complex movements in the fiber axis direction is enhanced, so that it can be suitably used for textiles such as clothing.

[0031] It is important that the conductive fiber of the present invention has a metal layer on the fiber surface. By having a metal layer on the fiber surface, it becomes possible to lower the volume resistivity of the conductive fiber, and sufficient conductivity for power transmission and signal transmission can be obtained.

[0032] The metal layer on the fiber surface in the conductive fiber of the present invention is not particularly limited as long as it satisfies the conductive performance of the present invention, but it is preferably formed of copper plating and / or silver plating. By forming the metal layer on the fiber surface of copper plating and / or silver plating, it becomes possible to lower the volume resistivity of the conductive fiber, and since it is easy to form the metal layer uniformly on the fiber surface, the conductivity and its fiber axis direction uniformity are improved. In addition, when the metal layer on the fiber surface is formed only of copper plating, although the conductivity decreases (the volume resistivity increases) compared with the case of forming only of silver plating, the cost can be suppressed.

[0033] The conductive fiber of the present invention has a volume resistivity of 2×10 -6 ~1×10 -2 Ω·cm is important. By setting the volume resistivity to 2×10 -6 Ω·cm or more, preferably 1×10 -5 Ω·cm or more, the proportion of the metal layer in the fiber cross-section substantially decreases, so that the mechanical properties such as strength are improved. Also, by setting the volume resistivity to 1×10 -2 Ω·cm or less, preferably 1×10 -3 Ω·cm or less, sufficient conductivity for power transmission and signal transmission can be obtained.

[0034] In addition, the volume resistivity in the present invention is determined as follows. (1) Keep a 10 cm long conductive fiber at a temperature of 25°C and a humidity of 65% RH for at least one hour. (2) Set the conductive fiber without applying tension so that it is in contact with the probe, which consists of two rod terminals connected to the insulation resistance meter with a distance of 5 cm between the terminals. (3) Measure the resistance (Ω) with an applied voltage of 100V, divide the obtained resistance by the probe distance of 5cm, and then measure the cross-sectional area A (cm²) of the conductive fiber used for measurement using the method described later. 2 Find the value obtained by multiplying by ). (4) The above measurement is performed five times for each level, changing the measurement location each time, and the arithmetic mean is taken as the volume resistivity (Ω·cm).

[0035] Here, in the present invention, if the conductive fiber is a monofilament, it is the volume resistivity of the monofilament alone, and if the conductive fiber is a multifilament, it is the volume resistivity of the entire multifilament. That is, in the case of a multifilament, the volume resistivity is the cross-sectional area A (cm²) of all the single fibers constituting the multifilament. 2 The sum of the above (3) is the cross-sectional area A (cm 2 This corresponds to ).

[0036] The conductive fiber of the present invention has a volume resistivity of 2 × 10 when stretched by 10% in the fiber axis direction. -6 ~1 × 10 -2 It is preferable that the density is Ω·cm. The volume resistivity when the fiber is stretched by 10% in the axial direction is preferably 2 × 10⁻⁶. -6 Ω·cm or more, more preferably 1 × 10⁻⁶ -5 By setting the volume resistivity to Ω·cm or higher, excessive changes in volume resistivity are eliminated even during stretching deformation, resulting in a conductive fiber with stable volume resistivity against deformation. Furthermore, the volume resistivity when stretched by 10% in the fiber axis direction is preferably 1 × 10⁻⁶. -2 Ω·cm or less, more preferably 1 × 10⁻¹⁰ -3 By keeping the resistivity below Ω·cm, there is no excessive increase in volume resistivity due to stretching deformation. Even when incorporated into textiles and subjected to complex movements, sufficient conductivity for power transmission and signal transmission can always be obtained, resulting in a conductive fiber with excellent electrical stability against deformation.

[0037] In this invention, the volume resistivity when the fiber is stretched by 10% in the axial direction is determined by stretching the conductive fiber by 10% from an unloaded state before setting it in contact with the probe when measuring the volume resistivity.

[0038] It is important that the conductive fibers of the present invention have a total fineness of 10 to 1000 dtex. By setting the total fineness to 10 dtex or more, preferably 20 dtex or more, and more preferably 30 dtex or more, it is possible to achieve a sufficiently low resistance value for power transmission and signal transmission, and the breaking strength of the fibers is increased, resulting in conductive fibers with excellent post-processability and durability. Furthermore, by setting the total fineness to 1000 dtex or less, preferably 800 dtex or less, and more preferably 500 dtex or less, conductive fibers that do not feel unnatural when incorporated into textiles such as clothing and have excellent wearability are obtained.

[0039] In this invention, total fineness is calculated by taking a 100m skein of conductive fiber, multiplying the mass of the skein by 100 to obtain the total fineness (dtex), taking five measurements for each level, and using the arithmetic mean. If the conductive fiber is shorter than 100m or cannot be taken in a skein, the length (m) and mass (g) of the conductive fiber may be measured, and the total fineness (dtex) may be calculated by mass (g) ÷ length (m) × 10000.

[0040] The conductive fibers of the present invention preferably have an average single fiber diameter of 5 to 20 μm. By setting the average single fiber diameter to preferably 5 μm or more, more preferably 6 μm or more, and even more preferably 7 μm or more, the strength of the single fiber is increased, reducing thread breakage due to friction and other abrasion, resulting in a conductive fiber with high durability. Furthermore, by setting the average single fiber diameter to preferably 20 μm or less, more preferably 18 μm or less, and even more preferably 16 μm or less, the fiber becomes flexible and easily conforms to deformation such as bending, so it does not feel unnatural when incorporated into textiles such as clothing, resulting in a conductive fiber with excellent wearability.

[0041] The average single fiber diameter in this invention is determined as follows. (1) A single fiber extracted from the multifilament is cut perpendicular to the fiber axis, and an image is taken using a scanning electron microscope at a magnification that allows the entire cross-section of the single fiber to be observed. (2) Using image analysis software, the cross-sectional area A formed by the cross-sectional contour of a single fiber is measured from the captured image, and the diameter (μm) of a perfect circle with the same area as this cross-sectional area A is calculated. (3) This procedure is performed on all single fibers constituting the multifilament, and the arithmetic mean is taken as the average single fiber diameter (μm).

[0042] When an eccentric core-sheath type is used as the composite form of the conductive fiber of the present invention, the degree of eccentricity in the cross-section of the single fiber is preferably 0.05 to 0.80. By setting the degree of eccentricity to preferably 0.05 or higher, more preferably 0.10 or higher, and even more preferably 0.15 or higher, the average crimp number increases, resulting in improved flexibility and a conductive fiber with excellent electrical stability against deformation. Furthermore, by setting the degree of eccentricity to preferably 0.80 or lower, more preferably 0.65 or lower, and even more preferably 0.50 or lower, the cross-section formation during the spinning process is improved, resulting in a conductive fiber with excellent process stability and fewer defects such as yarn breakage.

[0043] The degree of eccentricity in this invention is determined as follows. (1) A single fiber extracted from the multifilament is cut perpendicular to the fiber axis, and an image is taken using a scanning electron microscope at a magnification that allows the entire cross-section of the single fiber to be observed. (2) Using image analysis software, the centroid a obtained from the cross-section of the entire composite fiber and the centroid b obtained from the cross-section of only the core component are calculated from the captured images, and the degree of eccentricity is calculated from the following formula. Eccentricity = (distance between centroid a and centroid b) / (1 / 2 × average single fiber diameter)

[0044] The conductive fibers of the present invention can take any shape, such as spun yarn made of long or short fibers, but it is preferable that they be made of long fibers. Because the conductive fibers are made of long fibers, the unevenness of conductivity is reduced, resulting in a stable volume resistivity in the fiber axis direction, as well as conductive fibers with high productivity and excellent mechanical properties.

[0045] The conductive fiber of the present invention preferably has a tensile strength of 1.5 cN / dtex or higher. By having a tensile strength of preferably 1.5 cN / dtex or higher, and more preferably 2.0 cN / dtex or higher, yarn breakage during post-processing steps such as weaving and knitting is reduced, resulting in a conductive fiber with excellent process stability. On the other hand, there is no particular upper limit to the tensile strength in the present invention, but approximately 10.0 cN / dtex is a practical upper limit.

[0046] In this invention, the breaking strength is determined based on the tensile strength and elongation described in JIS L 1013:2010 8.5. The conductive fiber is set without tension, and the strength at the time of breaking (cN) is measured under the conditions of a sample length of 200 mm and a tensile speed of 200 mm / min. The strength (cN / dtex) is calculated by dividing this by the total fineness (dtex), and the arithmetic mean is obtained by performing five measurements for each level.

[0047] The conductive fibers of the present invention preferably have a break elongation of 15 to 200%. By setting the break elongation to preferably 15% or more, more preferably 20% or more, and even more preferably 30% or more, thread breakage during post-processing steps is reduced, resulting in conductive fibers with excellent process stability. Furthermore, by setting the break elongation to preferably 200% or less, more preferably 180% or less, and even more preferably 160% or less, the fibers become less susceptible to plastic deformation when stretched, resulting in conductive fibers with excellent durability.

[0048] In this invention, the elongation at break is determined based on the tensile strength and elongation ratio described in JIS L 1013:2010 8.5. The conductive fiber is set without tension, and the elongation (%) at break is measured under the conditions of a sample length of 200 mm and a tensile speed of 200 mm / min. Five measurements are taken for each level, and the arithmetic mean is used to determine the elongation at break.

[0049] The conductive fibers of the present invention preferably have a 10% modulus of 1.50 cN / dtex or less. By setting the 10% modulus to preferably 1.50 cN / dtex or less, more preferably 1.00 cN / dtex or less, and even more preferably 0.50 cN / dtex or less, the stress generated by deformation is reduced, resulting in a conductive fiber with excellent flexibility. On the other hand, there is no particular lower limit to the 10% modulus in the present invention, but 0.00 cN / dtex is a practical lower limit.

[0050] In this invention, the 10% modulus is determined by setting a conductive fiber without applying tension, based on the tensile strength and elongation described in JIS L 1013:2010 8.5, measuring the stress (cN / dtex) when the fiber is stretched by 10% under conditions of a sample length of 200 mm and a tensile speed of 200 mm / min, and performing five measurements for each level, and calculating the arithmetic mean.

[0051] The conductive fibers of the present invention possess high conductivity, electrical stability against deformation, and excellent flexibility. These characteristics allow them to be used in various applications, such as antistatic materials for clothing like stockings, tights, and dustproof clothing, textiles like curtains, and carpets, mats, and flooring for indoor and outdoor use, as well as in vehicles. They are particularly well-suited for use in smart textiles, such as for power transmission to drive devices incorporated into fabrics and for transmitting electrical signals from sensors. Furthermore, by incorporating the conductive fibers of the present invention into electrical and electronic equipment that requires movements such as stretching and bending, they can be suitably used for power transmission and electrical signal transmission from sensors.

[0052] [Clothing] The garment of the present invention is composed of at least a portion of the conductive fibers of the present invention. By including at least a portion of the conductive fibers of the present invention, the garment becomes comfortable to wear with no discomfort when worn.

[0053] The clothing of the present invention refers to items worn to cover the body partially or entirely, and includes not only tops, bottoms, or garments such as kimonos and coveralls, but also hats, gloves, socks, and other items. In particular, it is preferable to apply the present invention to smart textiles, which are clothing incorporating various devices, sensors, IC chips, and other electronic components, as this allows the conductive fibers of the present invention to fully demonstrate their characteristics, such as high conductivity, electrical stability against deformation, and flexibility.

[0054] For example, when the conductive fibers of the present invention are applied to smart textiles, their high flexibility due to crimping does not hinder human movement, and the total fineness is within a specific range, resulting in a smart textile with excellent wearing comfort and no discomfort when worn. Furthermore, because the conductive fibers of the present invention have a lower volume resistivity compared to fibers containing carbon black, they can transmit electricity as a power source for devices and transmit electrical signals from sensors, and also exhibit excellent electrical stability against deformation. Therefore, the conductive fibers of the present invention can be applied to smart textiles for a variety of applications.

[0055] In the present invention, when conductive fibers are used for power transmission, the portion where the conductive fibers are arranged may be covered with an insulating material. Covering the portion where the conductive fibers are arranged with an insulating material is preferable because it can prevent electric shock and other problems.

[0056] [Electrical and Electronic Equipment] The electrical and electronic equipment of the present invention is composed of at least a portion of the conductive fibers of the present invention. By including at least a portion of the conductive fibers of the present invention, the electrical or electronic equipment can perform movements such as stretching and bending smoothly and has excellent electrical stability against deformation.

[0057] The conductive fibers of the present invention not only enable the transmission of electricity and electrical signals from sensors, but also exhibit excellent electrical stability against deformation. Therefore, the conductive fibers of the present invention can be applied to various electrical and electronic equipment applications that require movements such as stretching and bending.

[0058] In the electrical and electronic equipment of the present invention, when conductive fibers are used for power transmission, the portion where the conductive fibers are arranged may be covered with an insulating material. Covering the portion where the conductive fibers are arranged with an insulating material is preferable because it can prevent electric shock and other dangers.

[0059] [Conductive fibers, and methods for manufacturing clothing and electrical / electronic equipment] Next, preferred embodiments for manufacturing the conductive fibers of the present invention will be described in detail.

[0060] The method for producing conductive fibers according to the present invention can be selected from methods such as solution spinning and melt spinning, but it is preferable to apply the melt spinning method because it has a low environmental impact and is easy to manufacture.

[0061] In the present invention, it is preferable to dry the thermoplastic polymer before spinning to prevent moisture contamination and remove oligomers, thereby improving its spinnability. Typically, vacuum drying at 80-200°C for 1-24 hours is used as the drying condition.

[0062] In melt spinning, melt spinning methods using extruders such as pressure melters, uniscrews, and twin-screw extruders can be applied. The extruded thermoplastic polymer is transported through piping, weighed by a metering device such as a gear pump, passes through a filter to remove foreign matter, and is then guided to a spinneret and discharged. When composite fibers are to be produced, each thermoplastic polymer is guided from separate piping to the spinneret, where its shape is restricted to a side-by-side type or eccentric core-sheath type before being combined and discharged as a composite fiber. The composite fiber obtained in this way is subjected to the drawing process described later to become a fiber with a three-dimensional coil shape.

[0063] When polyester or polyamide is used as the thermoplastic polymer, the temperature from the polymer piping to the spinneret (spinning temperature) is preferably 20°C or higher above the melting point of the thermoplastic polymer to increase fluidity, and preferably 320°C or lower to suppress thermal decomposition of the thermoplastic polymer.

[0064] In the spinneret used for extrusion, it is preferable that the diameter D of the spinneret hole be 0.1 mm or more and 0.6 mm or less, and that L / D, defined as the quotient obtained by dividing the land length L of the spinneret hole (length of the straight tube section with the same diameter as the spinneret hole) by the hole diameter, be 1 or more and 10 or less.

[0065] The fibers discharged from the nozzle holes are cooled and solidified by blowing cooling air (air) onto them. The temperature of the cooling air can be determined by balancing it with the cooling air velocity from the viewpoint of cooling efficiency, but it is preferable that it be 30°C or lower. By preferably keeping the temperature of the cooling air at 30°C or lower, the solidification behavior due to cooling is stabilized, resulting in conductive fibers with high fiber diameter uniformity.

[0066] Furthermore, it is preferable to direct the cooling air almost perpendicular to the undrawn fibers discharged from the nozzle. In this case, the speed of the cooling air is preferably 10 m / min or more from the viewpoint of cooling efficiency and uniformity of fiber diameter, and preferably 100 m / min or less from the viewpoint of yarn production stability. In addition, by setting the direction of cooling air discharge to one direction and cooling fibers using thermoplastic polymers with a large specific heat capacity or hollowed-out fibers, it is possible to obtain undrawn fibers having a difference in the degree of molecular orientation in the fiber cross-section direction, and it is also possible to obtain crimped fibers by subjecting these undrawn fibers to the drawing process described later.

[0067] The cooled and solidified undrawn fibers are taken up by a roller (godette roller) that rotates at a constant speed. The take-up speed is preferably 300 m / min or more for uniform fiber diameter and improved productivity, and preferably 4000 m / min or less to prevent yarn breakage.

[0068] The undrawn fibers obtained in this way are subjected to a drawing process immediately after being wound up or taken up. Drawing is performed by running the fibers through a heated first roller or a heating device installed between the first and second rollers, for example, in a heating bath or on a hot plate. The drawing conditions are determined by the mechanical properties of the obtained undrawn fibers, but the drawing temperature is determined by the temperature of the heated first roller or the heating device installed between the first and second rollers, and the drawing ratio is determined by the ratio of the peripheral speeds of the first and second rollers.

[0069] Furthermore, after passing through the second roller, the drawn fibers can be heated by a heated third roller, or by a heating device installed between the second and third rollers, to perform heat setting. Heat setting promotes crystallization, resulting in conductive fibers with excellent shape stability.

[0070] The stretched fibers obtained by the above manufacturing method can exhibit a three-dimensional coil shape in their stretched state by applying the aforementioned composite fiber formation and cooling condition adjustments. Furthermore, it is possible to impart mechanical crimping to the obtained stretched fibers using a crimper or gears.

[0071] The resulting crimped fibers are plated to form a metal layer on the fiber surface. The metal used for plating is not particularly limited as long as it satisfies the conductivity requirements of the present invention, but copper and / or silver are preferred in terms of conductivity and cost. The plating process can be any method that forms a metal layer on the crimped fibers, such as electroless plating, electrolytic plating, molten metal plating, vacuum deposition, chemical deposition, or physical deposition. In addition, a surface modification treatment may be performed before the plating process to facilitate the formation of the metal layer.

[0072] Conductive fibers, in which a metal layer is formed on the surface of crimped fibers obtained by the above manufacturing method, are incorporated into textiles such as woven or knitted fabrics. When incorporating them into woven or knitted fabrics, methods include using some or all of the conductive fibers of the present invention in the manufacturing process, or sewing the conductive fibers of the present invention onto a raw or knitted fabric made of other fibers. The textiles (woven or knitted fabrics) obtained in this way are then used to sew garments according to the present invention. Another method is to directly sew the conductive fibers of the present invention onto garments. Furthermore, when incorporating the conductive fibers of the present invention into electrical and electronic equipment, methods similar to those used for ordinary electrical wiring, such as copper wire, can be employed. [Examples]

[0073] Next, the present invention will be described in detail based on the examples. However, the present invention is not limited to these examples. Unless otherwise specified, the measurements of each physical property were performed based on the methods described above.

[0074] (1) Total fineness The measurements were performed using the "YC-1" electric measuring machine manufactured by Intec Co., Ltd., as described above.

[0075] (2) Average single fiber diameter For the single fibers extracted from the multifilament, images were captured using a scanning electron microscope "S-5500" manufactured by Hitachi High-Technologies Corporation at a magnification that allowed observation of the entire cross-section of the single fiber. Subsequently, measurements were performed using "WinROOF2015" image analysis software manufactured by Mitani Corporation, as described above.

[0076] (3) Average number of crimps As described above, single fibers extracted from multifilaments were measured using a digital microscope "VHX-2000" equipped with a wide-range zoom lens "VH-Z100R" manufactured by Keyence Corporation.

[0077] (4) Breaking strength, breaking elongation, 10% modulus The measurements were performed using the "Tensilon UCT100" tensile testing machine manufactured by Orientec Co., Ltd., as described above.

[0078] (5) Volume resistivity, volume resistivity at 10% elongation The measurements were performed using the "SM-8220" insulation resistance meter manufactured by Toa DKK Corporation, as described above.

[0079] (6) Electrical stability against deformation A stretch knitted polyester fabric without a conductive layer, having a break elongation of 15% or more in at least one direction (either vertically or horizontally) (pique knit, weight 170g / m²) 2 Two conductive fibers obtained in the examples and comparative examples were sewn parallel to each other for 15 cm each, with a 3 cm gap between them, in the direction of high elongation of the stretch fabric (running stitch, 0.5 cm intervals). Next, the stretch fabric was stretched by 10% in the direction of high elongation, then returned to an unloaded state, and the two sewing threads were secured by tying knots to prevent them from becoming loose. The terminals of a Nidec Corporation axial DC fan "D02X (rated voltage 5V)" were connected to the ends of the two sewing threads, and a DC power supply with an output voltage of 5V was connected to the other end of the sewing threads. Subsequently, while applying current to rotate the fan, the structure was repeatedly expanded and contracted (back and forth) by 10% at a speed of 3 seconds per cycle for 10 cycles. Those where "the fan rotates sufficiently and the fan speed does not change during the expansion and contraction operation" were evaluated as "A (Good)," those where "the fan speed changes during the expansion and contraction operation" were evaluated as "B (Slightly Poor)," and those where "the fan rotation is significantly slow or the fan rotation stops" were evaluated as "C (Poor)," thereby evaluating the electrical stability of the deformation.

[0080] [Example 1] High-viscosity polyethylene terephthalate (PET) with an intrinsic viscosity of 0.9 dL / g was used as polymer A, and low-viscosity PET with an intrinsic viscosity of 0.6 dL / g was used as polymer B. Both polymers were vacuum-dried at 150°C for 12 hours, and then melt-spun at a spinning temperature of 290°C. In melt spinning, the high-viscosity PET and low-viscosity PET were melt-extruded separately using twin-screw extruders and guided to the spindle while being weighed with a gear pump. Then, within the spindle, the two polymers were combined in a side-by-side configuration with a volume ratio of high-viscosity PET:low-viscosity PET = 50:50, and spun from a spindle with 36 round holes of 0.3 mmφ at a single-hole discharge rate of 0.82 g / min.

[0081] The yarn spun from the spindle passed through a 50 mm heat retention area and was then air-cooled for 1.0 m using a uniflow type cooling device at a temperature of 25°C and an airflow of 30 m / min. After that, an oil was applied 2.0 m below the spindle surface, and all 36 filaments were wound on a winder via a first and second godet roller at a speed of 1000 m / min to obtain undrawn fibers.

[0082] The undrawn fibers described above were taken up by a feed roller equipped with a nip roller, tension was applied to the undrawn fibers between the first and second rollers, and then heat-drawn by passing them around six times on the first and second rollers heated to 90°C. Furthermore, they were passed around six times on the third roller heated to 140°C for heat setting. The total draw ratio was 3.50 times, and after the third roller, the fibers were wound up on a winder via an unheated roller at a peripheral speed of 400 m / min to obtain the drawn fibers.

[0083] The surface of the stretched fibers described above was cleaned and degreased, then etched, and a palladium catalyst was supported on the fiber surface. Copper plating was then performed in an aqueous copper sulfate solution.

[0084] The obtained conductive fibers were evaluated for total fineness, average single fiber diameter, average crimp count, breaking strength, breaking elongation, volume resistivity, volume resistivity at 10% elongation, and electrical stability under deformation. The evaluation results are shown in Table 1.

[0085] [Examples 2 and 3] Conductive fibers were obtained using the same method as in Example 1, except that the single-hole extrusion rate in the spinning process was changed to 1.40 g / min in Example 2 and 0.56 g / min in Example 3. The evaluation results of the obtained conductive fibers are shown in Table 1.

[0086] [Example 4] Conductive fibers were obtained using the same method as in Example 1, except that the volume ratio in the spinning process was set to high-viscosity PET:low-viscosity PET = 20:80. The evaluation results of the obtained conductive fibers are shown in Table 1.

[0087] [Example 5] Conductive fibers were obtained in the same manner as in Example 1, except that polybutylene terephthalate (PBT) "Toraycon" 1200M, manufactured by Toray Industries, Inc., was used as polymer A. The evaluation results of the obtained conductive fibers are shown in Table 2.

[0088] [Example 6] Conductive fibers were obtained in the same manner as in Example 1, except that in the spinning process, polymer A was arranged as the sheath and polymer B as the core, resulting in an eccentric core-sheath type composite fiber with an eccentricity of 0.30. The evaluation results of the obtained conductive fibers are shown in Table 2.

[0089] [Comparative Example 1] Conductive fibers were obtained in the same manner as in Example 6, except that polypropylene terephthalate (PPT-CB) was obtained by melt-kneading Degussa Furnace Black (Type L, average particle size 23 μm) as polymer A, and PET (copolymerized PET) was obtained by copolymerizing 7 mol% isophthalic acid (IPA) and 4 mol% bisphenol A-ethylene oxide adduct (BPA-EO) as polymer B. The results of the evaluation of the obtained conductive fibers are shown in Table 2.

[0090] [Example 7] In the spinning process, only polymer A was spun using a hollow spinneret (slit width 0.08 mm, slit diameter 0.8 mm, 3 slits), and then air-cooled using a uniflow type cooling device at a wind speed of 50 m / min. Conductive fibers were obtained in the same manner as in Example 1, except that undrawn fibers with a difference in molecular orientation in the fiber cross-sectional direction were used. The evaluation results of the obtained conductive fibers are shown in Table 3.

[0091] [Comparative Example 2] As the drawn fiber, "Lycra T-127," a polyurethane elastic fiber manufactured by Toray Operontex Co., Ltd., was used, and conductive fibers were obtained by copper plating treatment in the same manner as in Example 1. The evaluation results of the obtained conductive fibers are shown in Table 3.

[0092] [Table 1]

[0093] [Table 2]

[0094] [Table 3]

[0095] Examples 1-7 were found to have excellent flexibility due to their total fineness being within a specific range, a large average crimp number, and a low 10% modulus. Furthermore, the presence of a metal layer resulted in low volume resistivity and excellent electrical stability against deformation.

[0096] On the other hand, Comparative Example 1 had a high volume resistivity, making it difficult for electricity to flow and preventing the fan from operating. In Comparative Example 2, the surface metal layer was destroyed when stretched by 10%, resulting in a significant decrease in conductivity and the fan stopping. Thus, it was found that Comparative Example 2 had poor electrical stability against deformation.

[0097] Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible without departing from the intent and scope of the invention. This application is based on Japanese Patent Application No. 2020-127087, filed on 28 July 2020, which is incorporated herein by reference in its entirety.

Claims

1. The average number of crimps is 4 or more, the crimp shape is a three-dimensional coil shape, and the fiber surface has a metal layer. Volume resistivity is 2 × 10⁻⁶ －６ ~1 x 10 －２ It is Ω·cm, Furthermore, when stretched by 10% in the fiber axis direction, the volume resistivity is 2 × 10 －６ ~1 x 10 －２ It is Ω·cm, Conductive fibers with a total fineness of 10 to 1000 dtex.

2. The conductive fiber according to claim 1, wherein the average single fiber diameter is 5 to 20 μm.

3. A conductive fiber according to claim 1 or 2, comprising long fibers.

4. The conductive fiber according to claim 3, wherein the long fiber is a multifilament consisting of a side-by-side type or eccentric core-sheath type composite fiber or hollow fiber.

5. A garment comprising at least a portion of conductive fibers as described in any one of claims 1 to 4.

6. Electrical and electronic equipment comprising at least a portion of conductive fibers as described in any one of claims 1 to 4.

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