Stretchable wire with high conductivity and high electrical stability and continuous preparation method thereof

Abstract

The invention discloses a stretchable wire with high conductivity and high electrical stability and a continuous preparation method of the stretchable wire. The stretchable wire is composed of an elastic base body and metal wires, wherein the metal wires are spirally wound around the elastic base body and partially embedded in the elastic base body. The continuous preparation method comprises the following steps: preparing an elastic matrix preform with a groove in the side surface; inserting an elastic matrix preform with grooves in the side surface into the plastic pipe, and performing vacuum heat treatment to obtain a composite preform; a metal wire penetrates through a groove in the side face of the elastic matrix preform from the upper end of the composite preform and is fixed to the lower end of the composite preform, then continuous heating and wire drawing are conducted (the composite preform is synchronously rotated in the wire drawing process), and composite fibers are obtained; and removing the plastic pipe on the surface of the composite fiber to obtain the stretchable wire. The stretchable wire has high conductivity and high electrical stability, and is suitable for various application scenes needing to realize stable electrical interconnection in a dynamic environment.

Description

Technical Field

[0001] The present invention relates to the field of flexible electronics, and particularly to a stretchable wire with both high conductivity and high electrical stability and a continuous preparation method thereof. Background Art

[0002] Stretchable wires combine conductivity, low modulus, and stretchability, and have important applications in fields such as flexible electronics. For example, as a connection for functional modules in wearable devices, it can significantly enhance the reliability of electrical interconnections and increase the wearing comfort of wearable devices; as an electrode to construct flexible fiber-type energy storage batteries, solar cells, supercapacitors, sensors, etc.; fabrics woven with stretchable wires can play roles such as electromagnetic shielding, electric heating and warming, and heat therapy, and due to their good flexibility, can improve the wearing comfort. In addition to the flexible electronics field, using stretchable wires for electrical interconnections at the joints of robots can greatly reduce the redundancy of wiring; replacing traditional brocade silk threads and being used for the voice coil connection of audio equipment can significantly improve the reliability and stability of electrical interconnections.

[0003] Currently reported stretchable wires mainly include two categories: "material stretchable" and "structure stretchable". "Material stretchable" type stretchable wires mainly mix conductive fillers (including metal micro-nano powders, carbon nanomaterials, conductive polymers, etc.) with elastic matrix materials (including TPE, silica gel, hydrogel, natural rubber, etc.), and are processed into fibers through techniques such as wet spinning, dry spinning, electrospinning, and hot drawing to obtain stretchable wires. This type of stretchable wire is easy to achieve continuous batch production, but its conductivity is relatively low and its electrical stability is relatively poor, thus limiting its practical applications. "Structure stretchable" type stretchable wires are generally prepared by constructing a continuous-phase conductive material with microstructures (such as wrinkles, networks, spirals, etc.) on the surface or inside of elastic matrix fibers that can effectively release tensile strain. This type of stretchable wire generally has high conductivity and electrical stability, but its preparation process is relatively complex and it is difficult to achieve continuous batch preparation.

[0004] In summary, although many types of stretchable wires and various preparation methods have been reported currently, there is still a lack of stretchable wires with both high conductivity and high electrical stability and a method that can achieve continuous batch preparation. Summary of the Invention

[0005] The purpose of the present invention is to provide a stretchable wire with both high conductivity and high electrical stability and a continuous preparation method thereof to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention: A stretchable wire with both high conductivity and high electrical stability, which is composed of an elastic matrix and a metal wire spirally wound around the elastic matrix and partially embedded in the elastic matrix.

[0008] That is, the stretchable wire includes a stretchable elastic matrix and a conductive metal wire; the conductive metal wire is wound around the elastic matrix to form a spiral structure and is partially embedded in the elastic matrix. Among them, partial embedding means that part of the cross-section of the metal wire is located within the cross-section of the elastic matrix and part is located outside the cross-section of the elastic matrix, that is, the cross-section of the metal wire and the cross-section of the elastic matrix partially overlap.

[0009] The stretchable wire of the present invention has both high conductivity and high electrical stability. The continuous-phase metal wire can provide high electrical conductivity, and its spiral structure can ensure good stretchability and provide high electrical stability at the same time. The metal wire is partially embedded inside the elastic matrix, which can make the metal wire and the elastic matrix firmly bonded, further improving the electrical stability. Part of the metal wire is exposed on the surface of the elastic matrix, which is beneficial to increasing the convenience of the electrical interconnection process and can be used as the electrode of the stretchable fibrous electronic device.

[0010] Further, the elastic matrix is a thermoplastic elastomer (TPE).

[0011] Further, the cross-sectional shape of the elastic matrix is circular.

[0012] Further, the metal wire includes copper wire, aluminum wire, nickel wire or steel wire (these metal wires have good electrical conductivity and mechanical strength).

[0013] Further, the cross-sectional shape of the metal wire is circular.

[0014] Further, the number of the metal wires ≥ 1.

[0015] Further, the diameter of the elastic matrix is 0.1 - 2 mm.

[0016] Further, the diameter of the metal wire is 0.01 - 0.5 mm.

[0017] Further preferably, the number of the metal wires is 1 - 10.

[0018] Further, the partial embedding includes: 1 / 3 - 4 / 5 arcs of the circumference of the circular cross-section of the metal wire are embedded in the elastic matrix.

[0019] Two of the technical solutions of the present invention: A continuous preparation method of the above stretchable wire with both high conductivity and high electrical stability, including the following steps:

[0020] Prepare an elastic matrix preform with grooves on its side; insert the elastic matrix preform with grooves on its side into a plastic tube, and perform vacuum heat treatment (so that the elastic matrix core rod and the plastic cladding are tightly bonded together through vacuum heat treatment) to obtain a composite preform; pass a metal wire through the grooves on the side of the elastic matrix preform from the upper end of the composite preform and fix it at the lower end of the composite preform, and then continuously heat and draw the wire to obtain a composite fiber; remove the plastic tube on the surface of the composite fiber to obtain the stretchable wire with both high conductivity and high electrical stability;

[0021] During the wire drawing process, rotate the composite preform synchronously so that the metal wire winds around the elastic matrix preform to form a spiral structure.

[0022] Further, the grooves are arranged longitudinally along the elastic matrix preform.

[0023] Further, the number of the grooves ≥ 1.

[0024] Further, the cross-sectional shape of the elastic matrix preform with grooves on its side is circular, and the diameter is 5 - 100 mm.

[0025] Further, the cross-sectional shape of the groove is an arc of 1 / 3 - 4 / 5.

[0026] Further, the ratio of the diameter of the arc to the diameter of the elastic matrix preform with grooves on its side is 0.01 - 0.5:0.1 - 2.

[0027] Further, the ratio of the diameter of the arc to the diameter of the elastic matrix preform with grooves on its side is equal to the ratio of the diameter of the metal wire to the diameter of the elastic matrix in the finally obtained stretchable wire with both high conductivity and high electrical stability, that is, the diameter of the arc / the diameter of the elastic matrix preform = the diameter of the metal wire / the diameter of the elastic matrix in the stretchable wire.

[0028] Further preferably, the number of the grooves is 1 - 10 (the number of the grooves is the same as the number of the metal wires).

[0029] Further, the inner diameter of the plastic tube is slightly larger than the outer diameter of the elastic matrix preform with grooves on its side.

[0030] Further, the preparation method of the elastic matrix preform with grooves on its side includes injection molding, extrusion or machining.

[0031] Further, the method for removing the plastic tube on the surface of the composite fiber includes mechanical peeling or solvent immersion.

[0032] Further, the softening temperature of the plastic tube is equal to or higher than the softening temperature of the elastic matrix preform.

[0033] Furthermore, the plastic tube can be dissolved by at least one solvent.

[0034] Furthermore, the material of the elastic matrix preform includes styrene-butadiene rubber (SBS), hydrogenated styrene-butadiene rubber (SEBS), or thermoplastic polyurethane (TPU).

[0035] Furthermore, the material of the plastic tube includes polymethyl methacrylate (PMMA), polyethyl methacrylate (PEMA), polycarbonate (PC), polyvinyl alcohol (PVA), polyethylene oxide (PEO), polyethylene glycol (PEG), or isomalt (all of these materials are thermoplastic polymer materials).

[0036] Furthermore, the solvent used to dissolve the plastic tube will not affect the elastic matrix and the metal wire.

[0037] Furthermore, the wire drawing is carried out in an optical fiber drawing tower.

[0038] In the method of the present invention, the groove size of the preform will shrink synchronously as the preform is drawn into a fiber. After being drawn into a fiber, the metal wire is closely attached to the outermost layer of plastic and the grooves of the elastic matrix. Removing the outermost layer of plastic results in part of the metal wire being exposed outside the grooves of the elastic matrix.

[0039] The third technical solution of the present invention: Application of the above stretchable wire with both high conductivity and high electrical stability in the preparation of flexible electronic devices.

[0040] The present invention discloses the following technical effects:

[0041] In the stretchable wire of the present invention, the metal wire is in a helical spring shape, which is wound around the elastic insulating matrix and partially embedded inside the elastic insulating matrix and partially exposed on the surface of the elastic insulating matrix. This fiber structure design can not only ensure good conductivity on the surface of the wire, but also ensure that the metal wire and the elastic matrix are closely combined, thus having good mechanical stability. The stretchable wire with a helical structure metal wire composite of the present invention has both high conductivity and high electrical stability, and is suitable for various application scenarios that require stable electrical interconnection in a dynamic environment (such as being used as voice coil tinsel wire, headphone wire, signal wire and power cord of wearable devices, etc.).

[0042] Traditional methods such as wet spinning, dry spinning, and electrospinning cannot prepare the stretchable wire with a special structure of the present invention. Moreover, the preparation methods reported for preparing "structurally stretchable" types of stretchable wires are difficult to achieve continuous preparation. The method disclosed in the present invention can achieve continuous preparation of a stretchable wire of the "structurally stretchable" type with both high conductivity and high electrical stability, can overcome the disadvantages of the prior art, and has good practical application prospects. The stretchable wire preparation method disclosed in the present invention can achieve precise control of the microstructure of the final stretchable wire by designing the structure of the preform at the macroscopic scale, and has a fast hot drawing speed and high stability during the drawing process. Therefore, the stretchable wire preparation method of the present invention has the characteristics of simple implementation and high production efficiency, and can achieve precise regulation of the wire size and microstructure, so it is suitable for continuous batch production of high-performance stretchable wires. Description of the Drawings

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0044] Figure 1 It is a schematic structural diagram of a stretchable wire with both high conductivity and high electrical stability of the present invention;

[0045] Figure 2 It is a schematic diagram of the preparation process of a stretchable wire with both high conductivity and high electrical stability of the present invention. Detailed Embodiments

[0046] Now, various exemplary embodiments of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0047] It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0048] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although this invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of this invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the said documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0049] Without departing from the scope or spirit of this invention, various improvements and changes can be made to the specific embodiments of the specification of this invention, which are obvious to those skilled in the art. Other embodiments obtained from the specification of this invention are obvious to those skilled in the art. The specification and examples of this invention are merely exemplary.

[0050] Regarding the use of "comprising", "including", "having", "containing", etc. in this text, they are all open-ended terms, meaning including but not limited to.

[0051] It should be noted that the parts not described in detail in this invention are all conventional operation means in the art and are not the focus of this invention.

[0052] As a first aspect of this invention, this invention provides a stretchable wire with both high conductivity and high electrical stability, which is composed of an elastic matrix and a metal wire spirally wound around the elastic matrix and partially embedded in the elastic matrix.

[0053] As a preferred embodiment of this invention, the elastic matrix is a thermoplastic elastomer (TPE).

[0054] As a preferred embodiment of this invention, the cross-sectional shape of the elastic matrix (including the part of the metal wire embedded in the matrix) is circular.

[0055] As a preferred embodiment of this invention, the metal wire includes copper wire, aluminum wire, nickel wire or steel wire (these metal wires have good electrical conductivity and mechanical strength).

[0056] And / or, the cross-sectional shape of the metal wire is circular.

[0057] As a preferred embodiment of this invention, the number of the metal wires ≥ 1; the structural schematic diagram of the stretchable wire with both high conductivity and high electrical stability is as Figure 1 shown.

[0058] As a preferred embodiment of this invention, the diameter of the elastic matrix is 0.1 - 2 mm.

[0059] As a preferred embodiment of the present invention, the diameter of the metal wire is 0.01 - 0.5 mm.

[0060] As a preferred embodiment of the present invention, the number of the metal wires is 1 - 10.

[0061] As a second aspect of the present invention, the present invention provides a continuous preparation method of the above stretchable wire with both high conductivity and high electrical stability, comprising the following steps (the schematic diagram of the preparation process is as shown in Figure 2 shown, Figure 2 only the method of removing the plastic tube by solvent immersion is shown):

[0062] Preparing an elastic matrix preform with grooves on the side (the grooves form a semi-open pore structure); inserting the elastic matrix preform with grooves on the side into a plastic tube, and performing vacuum heat treatment (the elastic matrix core rod and the plastic cladding are tightly combined together through vacuum heat treatment) to obtain a composite preform (i.e., an integrated preform with closed through holes on the side); passing a metal wire through the grooves on the side of the elastic matrix preform from the upper end of the composite preform and fixing it at the lower end of the composite preform, and then continuously heating and drawing (i.e., drawing to obtain continuous composite fibers) to obtain composite fibers; removing the plastic tube on the surface of the composite fibers to obtain the stretchable wire with both high conductivity and high electrical stability;

[0063] During the drawing process, the composite preform is synchronously rotated (rotating around the center of the preform) so that the metal wire winds around the elastic matrix preform to form a spiral structure.

[0064] As a preferred embodiment of the present invention, the grooves are arranged longitudinally along the elastic matrix preform.

[0065] As a preferred embodiment of the present invention, the number of the grooves ≥ 1.

[0066] As a preferred embodiment of the present invention, when the number of grooves > 1, the cross-sectional shapes and sizes of the grooves are the same.

[0067] As a preferred embodiment of the present invention, the cross-sectional shape of the elastic matrix preform with grooves on the side is circular (i.e., the elastic matrix preform is a round rod with a uniform diameter), and the diameter is 5 - 100 mm.

[0068] As a preferred embodiment of the present invention, the cross-sectional shape of the groove is 1 / 3 - 4 / 5 arc (i.e., the length of the arc is 1 / 3 - 4 / 5 of the circle).

[0069] As a preferred embodiment of the present invention, the ratio of the diameter of the arc to the diameter of the elastic matrix preform with grooves on the side is 0.01 - 0.5:0.1 - 2.

[0070] As a preferred embodiment of the present invention, the ratio of the diameter of the arc to the diameter of the elastic matrix preform with grooves on the side is equal to the ratio of the diameter of the metal wire to the diameter of the elastic matrix in the finally obtained stretchable wire with both high conductivity and high electrical stability, that is, the diameter of the arc / the diameter of the elastic matrix preform = the diameter of the metal wire / the diameter of the elastic matrix in the stretchable wire.

[0071] As a preferred embodiment of the present invention, the number of the grooves is 1 - 10 (the number of the grooves is the same as the number of the metal wires).

[0072] As a preferred embodiment of the present invention, the inner diameter of the plastic tube is slightly larger than the outer diameter of the elastic matrix preform with grooves on the side.

[0073] As a preferred embodiment of the present invention, the inner diameter of the plastic tube is 0.1 - 1 mm larger than the outer diameter of the elastic matrix preform with grooves on the side.

[0074] As a preferred embodiment of the present invention, the preparation method of the elastic matrix preform with grooves on the side includes injection molding, extrusion or machining.

[0075] As a preferred embodiment of the present invention, the method for removing the plastic tube on the surface of the composite fiber includes mechanical peeling or solvent immersion.

[0076] As a preferred embodiment of the present invention, the softening temperature of the plastic tube is equal to or higher than the softening temperature of the elastic matrix preform.

[0077] As a preferred embodiment of the present invention, the plastic tube can be dissolved by at least one solvent.

[0078] As a preferred embodiment of the present invention, the material of the elastic matrix preform includes styrene-butadiene rubber (SBS), hydrogenated styrene-butadiene rubber (SEBS) or thermoplastic polyurethane (TPU).

[0079] As a preferred embodiment of the present invention, the material of the plastic tube includes polymethyl methacrylate (PMMA), polyethyl methacrylate (PEMA), polycarbonate (PC), polyvinyl alcohol (PVA), polyethylene oxide (PEO), polyethylene glycol (PEG) or isomalt (these materials are all thermoplastic polymer materials).

[0080] As a preferred embodiment of the present invention, the solvent used to dissolve the plastic tube will not affect the elastic matrix and the metal wire.

[0081] As a preferred embodiment of the present invention, the wire drawing is carried out in an optical fiber drawing tower.

[0082] As the third aspect of the present invention, the present invention provides the application of the above stretchable wire with both high conductivity and high electrical stability in the preparation of flexible electronic devices.

[0083] The technical solutions of the present invention will be further described below in conjunction with specific embodiments.

[0084] In the specific embodiments of the present invention, if room temperature is involved, it specifically refers to 20 - 30 °C.

[0085] All raw materials used in the specific embodiments of the present invention are ordinary commercially available products.

[0086] Example 1

[0087] A stretchable wire with both high conductivity and high electrical stability is composed of an elastic matrix and conductive metal wires (the number is 3). Among them, the elastic matrix is hydrogenated styrene-butadiene rubber (SEBS, Kraton G1657), and the metal wire is a copper wire. The copper wire is spirally wound around the hydrogenated styrene-butadiene rubber matrix, and about 2 / 3 of the arc (that is, the arc accounting for 2 / 3 of the circular circumference of the metal wire cross-section) is embedded in the hydrogenated styrene-butadiene rubber matrix. The cross-sectional shape of the hydrogenated styrene-butadiene rubber matrix (including the part of the metal wire embedded in the matrix) is circular, and its diameter is 1 mm. The cross-sectional shape of the complete copper wire is circular, and its diameter is 0.05 mm. The pitch of the copper wire helix is 0.2 mm.

[0088] A continuous preparation method for a stretchable wire with both high conductivity and high electrical stability is as follows:

[0089] (1) Use a twin-screw extruder to prepare a hydrogenated styrene-butadiene rubber round rod with a diameter of 30 mm and a length of 300 mm with 3 grooves on the side by heating and extrusion. The cross-sectional shape of each groove is a 2 / 3 arc with a diameter of 1.5 mm (that is, the length of the arc is 2 / 3 of the circle with a diameter of 1.5 mm). The 3 grooves are evenly arranged longitudinally around the hydrogenated styrene-butadiene rubber round rod, and it is used as a thermoplastic elastomer preform with grooves on the side.

[0090] (2) Insert the hydrogenated styrene-butadiene rubber round rod with grooves on the side (i.e., the preform) prepared in step (1) into a polymethyl methacrylate (Macklin ordinary injection grade) round tube with an inner diameter of 31 mm, a wall thickness of 3 mm, and a length of 300 mm. Then, heat at 180 °C for 30 min in a vacuum environment to tightly bond the hydrogenated styrene-butadiene rubber round rod with grooves on the side and the polymethyl methacrylate round tube together to form an integrated preform with a closed through-hole on the side.

[0091] (3) Vertically fix the integrated preform with closed through-holes on the side prepared in step (2) on the preform fixture of the optical fiber drawing tower. Then install 3 coils of commercial copper wires with a diameter of 0.05 mm above the preform. Next, let the wire heads of the 3 coils of copper wires pass through 1 through-hole of the preform respectively and fix them together with the lower end of the preform. The copper wire coils can rotate freely when the copper wires are drawn out to ensure that the copper wires can be smoothly drawn out during the drawing process. The fixtures for clamping the preform and the copper wire coils are controlled by a motor and can move up and down and rotate.

[0092] (4) Lower the preform with copper wires passing through it in step (3) into the heating furnace of the optical fiber drawing tower, and then raise the temperature to the softening temperature of the preform (near 185 °C) and start drawing at a certain speed. The composite fiber obtained by drawing is wound by the winding device below the drawing tower. During the drawing process, control the preform fixture to slowly descend and rotate synchronously (driving the preform and the copper wire to rotate around the center of the preform). Regulate the diameter of the fiber by jointly controlling the lowering speed of the preform and the drawing speed of the fiber. Regulate the pitch of the copper wire spiral structure by jointly controlling the rotation speed of the preform and the drawing speed of the fiber. During the drawing process, the diameter of the through-hole formed by the groove of the hydrogenated styrene-butadiene rubber matrix and the polymethyl methacrylate circular tube cladding decreases in the same proportion as the diameter of the preform. When the elastic matrix is drawn into a fiber with a diameter of about 1 mm, the diameter of the through-hole is just about equal to the diameter of the copper wire.

[0093] (5) Immerse the composite fiber obtained in step (4) in glacial acetic acid to dissolve and remove the polymethyl methacrylate cladding on its surface, and obtain the final stretchable wire with both high conductivity and high electrical stability after cleaning and drying.

[0094] By changing the length of the hydrogenated styrene-butadiene rubber rod, the on-line continuous preparation of longer-specification stretchable wires can be realized.

[0095] Example 2

[0096] A stretchable wire with both high conductivity and high electrical stability, which is only different from Example 1 in that the elastic matrix is replaced by styrene-butadiene rubber (Yanshan Petrochemical SBS1401), and other structures, parameters and preparation methods are the same as those in Example 1.

[0097] Example 3

[0098] A stretchable wire with both high conductivity and high electrical stability, which is only different from Example 1 in that the hydrogenated styrene-butadiene rubber of the elastic matrix is replaced by thermoplastic polyurethane (BASF 1170AU, Germany), and other structures, parameters and preparation methods are the same as those in Example 1.

[0099] Example 4

[0100] A stretchable wire with both high electrical conductivity and high electrical stability, which is only different from Example 1 in that the conductive copper wire is replaced with a nickel wire, and other structures, parameters and preparation methods are the same as those in Example 1.

[0101] Example 5

[0102] A stretchable wire with both high electrical conductivity and high electrical stability, which is only different from Example 1 in that the conductive copper wire is replaced with an aluminum wire, and other structures, parameters and preparation methods are the same as those in Example 1.

[0103] Example 6

[0104] A stretchable wire with both high electrical conductivity and high electrical stability, which is only different from Example 1 in that the conductive copper wire is replaced with an iron wire, and other structures, parameters and preparation methods are the same as those in Example 1.

[0105] Example 7

[0106] A stretchable wire with both high electrical conductivity and high electrical stability, which is different from Example 1 in that the number of conductive copper wires is changed from 3 to 1. Other structures and parameters of the stretchable wire are the same as those in Example 1. The number of open grooves of the hydrogenated styrene-butadiene rubber round rod used in the preparation process of the stretchable wire is correspondingly changed to 1. The shape and size of the groove are the same as those in Example 1.

[0107] Example 8

[0108] A stretchable wire with both high electrical conductivity and high electrical stability, which is different from Example 1 in that the number of conductive copper wires is changed from 3 to 5, and the 5 copper wires are evenly distributed around the elastic matrix. Other structures and parameters of the stretchable wire are the same as those in Example 1. The number of open grooves of the hydrogenated styrene-butadiene rubber round rod used in the preparation process of the stretchable wire is correspondingly changed to 5, and they are evenly distributed around the round rod. The shape and size of the groove are the same as those in Example 1.

[0109] Example 9

[0110] A stretchable wire with both high electrical conductivity and high electrical stability, which is only different from Example 1 in that the pitch of the copper wire is changed from 0.2 mm to 0.1 mm, and other structures and parameters are the same as those in Example 1. During the preparation process, with the constant lowering speed and drawing speed of the preform, the rotation speed of the preform is increased to 2 times the rotation speed of the preform in Example 1. Or with the constant rotation speed and lowering speed of the preform, the drawing speed is changed to 0.5 times the drawing speed in Example 1.

[0111] Example 10

[0112] A stretchable wire with both high conductivity and high electrical stability, which is only different from Example 1 in that the pitch of the copper wire changes from 0.2 mm to 0.4 mm, and other structures and parameters are the same as those in Example 1. During the preparation process, with the constant lowering speed of the preform and the drawing speed, the rotation speed of the preform is reduced to 0.5 times the rotation speed of the preform in Example 1. Or with the constant rotation speed and lowering speed of the preform, the drawing speed is increased to 2 times the drawing speed in Example 1.

[0113] Example 11

[0114] A stretchable wire with both high conductivity and high electrical stability, whose structure and parameters are the same as those in Example 1. In step (2) of the preparation process, a polycarbonate (Chi Mei PC-110 from Taiwan, China) round tube is used to replace the polymethyl methacrylate round tube, and its inner diameter, wall thickness and length are the same as those of the polymethyl methacrylate round tube used in Example 1. Other parameters and conditions of the preparation process are the same as those in Example 1.

[0115] Example 12

[0116] A stretchable wire with both high conductivity and high electrical stability, whose structure and parameters are the same as those in Example 1. In step (2) of the preparation process, a polyethyl methacrylate (Macklin Mw~515000) round tube is used to replace the polymethyl methacrylate round tube, and its inner diameter, wall thickness and length are the same as those of the polymethyl methacrylate round tube used in Example 1. Other parameters and conditions of the preparation process are the same as those in Example 1.

[0117] Example 13

[0118] A stretchable wire with both high conductivity and high electrical stability, whose structure and parameters are the same as those in Example 1. In step (2) of the preparation process, a polyvinyl alcohol (Kuraray PVA117 from Japan) round tube is used to replace the polymethyl methacrylate round tube, and its inner diameter, wall thickness and length are the same as those of the polymethyl methacrylate round tube used in Example 1. The method of removing the polyvinyl alcohol outer layer after fiber drawing in this example is slightly different from that in step (5) of Example 1. In this example, water is used to replace glacial acetic acid.

[0119] Example 14

[0120] A stretchable wire with both high conductivity and high electrical stability, whose structure and parameters are the same as those in Example 1. In step (2) of the preparation process, a polyethylene oxide (Sumitomo PEO-800 from Japan) round tube is used to replace the polymethyl methacrylate round tube, and its inner diameter, wall thickness and length are the same as those of the polymethyl methacrylate round tube used in Example 1. Other parameters and conditions of the preparation process are the same as those in Example 1.

[0121] Example 15

[0122] A stretchable wire with both high conductivity and high electrical stability, having the same structure and parameters as in Example 1. In step (2) of the preparation process, an isomalt (BENE Isomalt ST-M E593 from Germany) round tube was used to replace the polymethyl methacrylate round tube, with the same inner diameter, wall thickness, and length as the polymethyl methacrylate round tube used in Example 1. Other parameters and conditions of the preparation process were the same as in Example 1.

[0123] Comparative Example 1

[0124] A braided stretchable wire, the preparation steps are as follows:

[0125] (1) Prepare hydrogenated styrene-butadiene rubber (Kraton G1657) fibers with a diameter of 1 mm by hot wire drawing;

[0126] (2) Pre-stretch SEBS fibers with a diameter of 1 mm (elongation strain 500%);

[0127] (3) Interweave 3 copper wires with a diameter of 0.05 mm and 5 fabric fibers on the pre-stretched SEBS fiber core, and release the pre-strain after weaving to achieve the stretchability of the overall structure, obtaining the final stretchable wire. Its diameter is about 1.1 mm, and the pitch of the helical copper wire in the wire is about 0.4 mm.

[0128] Comparative Example 2

[0129] A stretchable wire with an overall helical structure, the preparation steps are as follows:

[0130] (1) Prepare SEBS (Kraton G1657) fibers with a diameter of 1 mm by hot wire drawing;

[0131] (2) Pre-stretch SEBS fibers with a diameter of 1 mm (elongation strain 500%);

[0132] (3) Closely attach 3 copper wires with a diameter of 0.05 mm to the surface of the pre-stretched SEBS fibers in step (2) (3

[0133] copper wires are evenly distributed);

[0134] (4) Coat the surface of the pre-stretched SEBS fibers and copper wires closely attached together obtained in step (3) with SEBS aqueous emulsion by dip coating and dry thoroughly;

[0135] (5) Release the pre-strain to obtain a stretchable wire with a helical structure (the whole wire has a helical structure). Its diameter is about 1.1 mm, and the pitch of the helical structure is about 0.2 mm.

[0136] Comparative Example 3

[0137] A stretchable wire with all metal wires embedded inside an elastic matrix, the preparation steps are as follows:

[0138] (1) Prepare a SEBS (Kraton G1657) round rod with 3 circular through-holes by methods such as injection molding and extrusion. The diameter of the SEBS round rod is 30 mm, the length is 300 mm, the diameter of its circular through-hole is 3 mm, the distance from the center of the through-hole to the center of the SEBS round rod is 10 mm, and the through-holes are evenly distributed on the circumference of the SEBS round rod;

[0139] (2) Vertically fix the SEBS round rod with through-holes prepared in step (1) on the preform fixture of the fiber drawing tower. Then install 3 coils of commercial copper wires with a diameter of 0.05 mm above the preform. Then let the wire heads of each coil of copper wire pass through 1 through-hole of the SEBS round rod respectively and be fixed together with the lower end of the SEBS round rod. The copper wire coils can rotate freely when the copper wire is pulled out, ensuring that the copper wire can be smoothly pulled out during the wire drawing process. The fixtures for clamping the preform and the copper wire coils are controlled by a motor and can move up and down and rotate.

[0140] (3) Lower the preform with copper wires passing through it in step (2) into the heating furnace of the fiber drawing tower, and then raise the temperature to the softening temperature of the preform (near 185 °C) and start wire drawing at a certain speed. The composite fiber obtained by wire drawing is wound up by the winding device below the wire drawing tower. During the wire drawing process, control the preform fixture to slowly move downward and rotate synchronously (driving the preform and the copper wire to rotate around the center of the preform). Regulate the diameter of the fiber by jointly controlling the lowering speed of the preform and the wire drawing speed of the fiber. Regulate the pitch of the copper wire spiral structure by jointly controlling the rotation speed of the preform and the wire drawing speed of the fiber, and obtain a stretchable wire with a pitch of the spiral structure of 0.2 mm and a diameter of about 1 mm.

[0141] Test Example 1

[0142] Test the stretch ratio, line resistivity, and electrical stability of the stretchable wires prepared in each example and comparative example. The test methods are as follows, and the test results are shown in Table 1.

[0143] Test method for the stretch ratio: The length of the wire sample is 5 cm, and both ends are clamped by the sample fixtures of the universal mechanical testing machine. The length of the stretchable section is 3 cm. During the stretch test, the stretch speed is 3 mm / s, and the stress-strain data is synchronously recorded by computer software until the wire is broken and the stretch is immediately stopped to complete the test.

[0144] Test method for linear resistivity: The length of the wire sample is 10 cm. The two ends of the wire are clamped with copper clamps and fixed on the stator and the moving platform of the automatic tensile machine. The clamps are respectively connected to the two electrodes of the Keithley 2400 source meter. The moving platform of the moving tensile machine pulls the wire (but does not stretch it). Use a ruler to accurately measure the length of the free section of the wire, denoted as L. Measure the resistance of the free section of the wire with the source meter, denoted as R. Then the linear resistivity (R L ) is calculated using the formula R L = R / L.

[0145] Test method for electrical stability of the wire: After the measurement of the linear resistivity is completed, turn on the automatic tensile machine to stretch the wire, and use computer software to record the stretching distance and resistance of the wire in real time. Convert the stretching distance into the stretching strain of the wire, and the resistance of the wire under a specific stretching strain can be obtained. The above stretching process can set a specific stretching strain and perform repeated tests to evaluate the stability of the wire under repeated stretching.

[0146] Table 1

[0147]

[0148]

[0149] As can be seen from Table 1, the stretchable wire prepared in the embodiment of the present invention has extremely high stretchability, conductivity, and electrical stability. In addition, by comparing Example 1 and Comparative Example 1, it can be seen that compared with other helical structure stretchable wires prepared by other methods, the stretchable wire prepared in the embodiment of the present invention has a higher stretchability. On the other hand, the stretchable wire obtained in Example 1 has no insulating coating, and the peeling operation of the insulating coating can be omitted in actual electrical interconnection operations, which can improve the efficiency of electrical interconnection operations. In addition, since the surface of the stretchable wire obtained in Example 1 has conductivity, it can be used as a stretchable electrode for preparing fiber-type stretchable devices (such as stretchable fiber-type lithium batteries, stretchable fiber-type solar cells, stretchable fiber-type triboelectric energy harvesters, etc.). In addition, in the method for preparing the stretchable wire adopted in Example 1, the preparation of the SEBS core layer and the winding of the copper wire are carried out synchronously, and there is no need to independently prepare stretchable SEBS fibers and then wind the copper wire subsequently, and there is no need to pre-stretch the SEBS fibers. Therefore, the method adopted in Example 1 is simpler and more efficient.

[0150] Compared with Comparative Example 2, in the stretchable wire obtained in Example 1, the copper wire part of the spiral structure is embedded in the SEBS matrix, and the macroscopic shape of the whole wire is a straight structure, rather than the whole wire presenting a spiral structure as in Comparative Example 2. The structure of the present invention is more conducive to wiring operations in practical applications. Moreover, the stretchable wire obtained in Example 1 has no insulating coating, which can simplify the electrical interconnection operation in practical applications and is used as the electrode material for stretchable fiber-type electronic devices. In addition, in the preparation method of the stretchable wire adopted in Example 1, the winding of the copper wire and the wire drawing process of the SEBS elastic matrix fiber are carried out synchronously, and there is no need to pre-stretch the elastic matrix fiber, so it is simpler and more efficient.

[0151] Compared with Comparative Example 3, the copper wire part in the stretchable wire obtained in Example 1 is exposed on the surface of the SEBS matrix, and its surface has conductivity. There is no need to strip the insulating coating on the surface during actual electrical interconnection operations, so the electrical interconnection operation can be simplified. On the other hand, the stretchable wire with surface conductivity can also be used as the electrode material for stretchable fiber-type electronic devices.

[0152] The above-described embodiments are only descriptions of the preferred modes of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A stretchable wire with both high electrical conductivity and high electrical stability, characterized in that, It is composed of an elastic matrix and a metal wire spirally wound around the elastic matrix and partially embedded in the elastic matrix.

2. The stretchable wire with both high conductivity and high electrical stability as described in claim 1, characterized in that, The elastic matrix is a thermoplastic elastomer; and / or, the cross-sectional shape of the elastic matrix is circular; and / or, the metal wire includes copper wire, aluminum wire, nickel wire or steel wire; and / or, the cross-sectional shape of the metal wire is circular.

3. The stretchable wire with both high conductivity and high electrical stability as claimed in claim 1, wherein The number of the metal wires ≥ 1.

4. The stretchable wire with both high conductivity and high electrical stability as described in claim 1, characterized in that, The diameter of the elastic matrix is 0.1 - 2 mm; and / or, the diameter of the metal wire is 0.01 - 0.5 mm.

5. A continuous preparation method of a stretchable wire having both high conductivity and high electrical stability as described in any one of claims 1-4, characterized in that, It includes the following steps: Prepare an elastic matrix preform with grooves on the side; insert the elastic matrix preform with grooves on the side into a plastic tube, and perform vacuum heat treatment to obtain a composite preform; pass the metal wire through the grooves on the side of the elastic matrix preform from the upper end of the composite preform and fix it at the lower end of the composite preform, and then continuously heat and draw to obtain a composite fiber; remove the plastic tube on the surface of the composite fiber to obtain the stretchable wire with both high conductivity and high electrical stability; During the wire drawing process, the composite preform is synchronously rotated so that the metal wire is wound around the elastic matrix preform to form a spiral structure.

6. The continuous preparation method according to claim 5, characterized in that, The grooves are arranged longitudinally along the elastic matrix preform; and / or, the number of the grooves ≥ 1; and / or, the cross-sectional shape of the elastic matrix preform with grooves on the side is circular, and the diameter is 5 - 100 mm; and / or, the cross-sectional shape of the grooves is 1 / 3 - 4 / 5 arc.

7. The continuous preparation method according to claim 5, characterized in that, The preparation method of the elastic matrix preform with grooves on the side includes injection molding, extrusion or machining; and / or, the method of removing the plastic tube on the surface of the composite fiber includes mechanical peeling or solvent immersion.

8. The continuous preparation method according to claim 5, characterized in that, The softening temperature of the plastic tube is equal to or higher than the softening temperature of the elastic matrix preform; and / or, the plastic tube can be dissolved by at least one solvent.

9. The continuous preparation method according to claim 8, characterized in that, The material of the elastic matrix preform includes styrene-butadiene rubber, hydrogenated styrene-butadiene rubber or thermoplastic polyurethane; and / or, the material of the plastic tube includes polymethyl methacrylate, polyethyl methacrylate, polycarbonate, polyvinyl alcohol, polyethylene oxide, polyethylene glycol or isomaltose.

10. Application of a stretchable wire with both high conductivity and high electrical stability according to any one of claims 1 - 4 in the preparation of flexible electronic devices.

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