Bending-resistant anti-cracking bundled insulated wire and preparation method thereof

Abstract

The invention belongs to the technical field of power transmission wires, and discloses a bending-resistant anti-cracking bundled insulated wire and a preparation method thereof. According to the invention, the conductor adopts a stepped unequal-diameter stranded structure, and in cooperation with in-situ annealing treatment, the flexibility and fatigue resistance of the conductor are improved; the insulating layer adopts a sandwich gradient composite structure, so that the inner layer is soft, the middle layer is tough, the outer layer is wear-resistant, bending stress can be effectively dispersed, and cracking of the insulating layer is avoided; and the protection layer and the insulation layer are mechanically interlocked through the micro ribs and the grooves, and the bonding effect of the identification layer is combined, so that the interlayer bonding is tight, the stripping phenomenon is avoided, and the bending resistance is further improved. The wire is good in overall flexibility, facilitates wiring and bending in complex scenes, improves the construction efficiency, has excellent high and low temperature resistance and aging resistance, can be widely applied to scenes needing frequent bending and complex wiring such as building interior lines, new energy equipment and mobile electrical equipment, and is high in practicability.

Description

Technical Field

[0001] This invention relates to the field of power transmission conductor technology, and in particular to a bend-resistant and crack-resistant bundled insulated conductor and its preparation method. Background Technology

[0002] Bundled insulated conductors are widely used in various power transmission scenarios due to their compact structure, small footprint, and convenient installation. However, existing bundled conductors are prone to the following problems in actual use, especially in complex environments such as repeated bending, friction and wear, or high and low temperatures: The stranding structure of individual conductors is unreasonable, leading to copper wire breakage and conductor loosening during bending, resulting in decreased conductivity; the insulation layer is not tightly bonded to the conductor and protective layer, easily causing interlayer peeling and cracking during bending, leading to insulation failure; insufficient filling of the gaps between the bundled conductor cores causes friction between the cores during bending, exacerbating conductor damage; and the outer protective structure has poor wear resistance and bending resistance, easily leading to sheath cracking and shielding layer damage after long-term use, affecting the electromagnetic compatibility and overall mechanical strength of the conductor. Summary of the Invention

[0003] The purpose of this invention is to provide a bend-resistant and crack-resistant bundled insulated wire and its preparation method, thereby solving the problems of easy cracking and short service life of existing bundled wires when bent.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a bend-resistant and crack-resistant bundled insulated wire, which comprises, from the inside out: a multi-wire stranded filling core layer, a shielding layer, and an outer sheath layer; The multi-wire stranded filling core layer consists of multiple stranded wires, with silicone rubber covering the surface of the stranded bundle and filling the gaps between the wires. The single conductor in the multi-wire stranded filler core layer comprises, from the inside out: a conductor, a marking layer, an insulation layer, and a protective layer; the conductor is made of non-uniform diameter copper wire stranded in layers; the marking layer is made of double-sided functionalized polyester tape, one side being a color-printed layer, and the other side being coated with a blend of silane coupling agent and thermoplastic elastomer; the insulation layer is a composite structure with an inner layer of silicone rubber and TPE blend, a middle layer of TPE and nano-boron nitride composite material, and an outer layer of silicone rubber modified TPE; the protective layer is a blend of TPU, modified graphene, and wear-resistant ceramic material; The shielding layer is made of braided metal wire; The outer sheath layer is made of cross-linked polyolefin.

[0005] Furthermore, in the aforementioned bend-resistant and crack-resistant bundled insulated wire, the silicone rubber coating thickness in the multi-wire stranded filler core layer is ≥0.38mm, and the silicone rubber filling density in the multi-wire stranded filler core layer is ≥95%.

[0006] Furthermore, in the aforementioned bend-resistant and crack-resistant bundled insulated wire, the non-equal diameter copper wires are layered and twisted as follows: the copper wires are divided into a central layer, a first outer layer, and a second outer layer, with the ratio of the number of copper wire strands in the central layer, the first outer layer, and the second outer layer being 1:6:12, the ratio of the diameter of the copper wires in the central layer, the first outer layer, and the second outer layer being 0.52:0.28:0.15, and the twisting pitch ratio of the central layer, the first outer layer, and the second outer layer being 8~10:10~12:12~14.

[0007] Furthermore, in the aforementioned bend-resistant and crack-resistant bundled insulated wire, the conductor is also subjected to in-situ annealing and surface micro-roughening treatment in sequence.

[0008] Furthermore, in the aforementioned bend-resistant and crack-resistant bundled insulated wire, the silane coupling agent in the marking layer accounts for 3-10 wt% of the blend of silane coupling agent and thermoplastic elastomer; The thickness of the marking layer is 0.05~0.08mm, and the coating thickness of the silane coupling agent and thermoplastic elastomer blend is 0.02~0.03mm.

[0009] Furthermore, in the aforementioned bend-resistant and crack-resistant bundled insulated wire, the inner layer contains 60-70% silicone rubber by mass, with the remainder being TPE; The boron nitride nanoparticles in the middle layer have a mass fraction of 1-5%, with the balance being TPE; the particle size of the boron nitride nanoparticles is 50-100 nm. The insulation layer has an inner layer thickness of 0.2~0.3mm, a middle layer thickness of 0.1~0.2mm, and an outer layer thickness of 0.2~0.3mm.

[0010] Furthermore, in the aforementioned bend-resistant and crack-resistant bundled insulated wire, the outer layer of the insulation layer is further enhanced with a surface hydrophobic additive, which is 1-2 wt% of the mass of silicone rubber modified TPE.

[0011] Furthermore, in the aforementioned bend-resistant and crack-resistant bundled insulated wire, the protective layer contains 1-5% modified graphene by mass, 3-8% wear-resistant ceramic by mass, and the remainder is TPU. The thickness of the protective layer is 0.3~0.5mm.

[0012] Furthermore, in the aforementioned bend-resistant and crack-resistant bundled insulated wire, the insulation layer has a raised ridge structure on the surface in contact with the protective layer, and the protective layer has a groove structure on the surface in contact with the insulation layer. The raised ridge structure and the groove structure match to form a mechanical interlocking structure.

[0013] This invention also provides a method for preparing a bend-resistant and crack-resistant bundled insulated wire, comprising the following steps: (1) Copper wires are mixed and twisted with non-equal diameters to obtain a conductor; double-sided functionalized polyester tape is wrapped around the conductor to obtain a conductor with a marking layer; a co-extrusion process is used to sequentially wrap a silicone rubber and TPE blend, a TPE and nano boron nitride composite material, and silicone rubber modified TPE around the marking layer to obtain a conductor with an insulation layer and a marking layer; finally, a TPU, modified graphene and wear-resistant ceramic blend is wrapped around the insulation layer to obtain a wire. (2) Select multiple wires and bundle them together; send the bundled wire cores after stranding into a filling machine, cover them with silicone rubber and fill them, and after curing, obtain a multi-wire stranded filling core layer; (3) Apply silane coupling agent to the outside of the multi-wire stranded filling core layer, and braid metal wire is used for braiding and covering to obtain a shielding layer; (4) Cross-linked polyolefin is melt-extruded and coated on the outside of the shielding layer. After curing, a bend-resistant and crack-resistant bundled insulated wire is obtained.

[0014] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects: (1) The conductor of this application adopts a stepped non-equal diameter stranded structure, combined with in-situ annealing treatment, which improves the flexibility and fatigue resistance of the conductor; the insulation layer adopts a sandwich gradient composite structure, which makes the inner layer soft, the middle layer tough and the outer layer wear-resistant, effectively dispersing bending stress and avoiding cracking of the insulation layer; the protective layer and the insulation layer are mechanically interlocked by micro-protrusion ridges and grooves, combined with the bonding effect of the marking layer, the interlayer bonding is tight and there is no peeling phenomenon, further improving the bending resistance.

[0015] (2) The protective layer of this application is made of TPU / modified graphene / wear-resistant ceramic blend material, which significantly improves the wear resistance and tear resistance of the conductor; the outer sheath is made of cross-linked polyolefin material, which has excellent mechanical protection capabilities and can effectively resist external friction and impact, and extend the service life of the conductor.

[0016] (3) The conductor of this application uses high-purity oxygen-free copper wire, which is optimized by stranding and surface treatment to ensure excellent conductivity, while avoiding the decrease in conductivity caused by copper wire breakage and loosening when bending; the shielding layer has a high braiding density, which can effectively suppress electromagnetic interference and ensure stable signal transmission.

[0017] (4) The conductor of this application has good overall flexibility, which is convenient for wiring and bending in complex scenarios and improves construction efficiency.

[0018] (5) This application has excellent high and low temperature resistance and aging resistance, and can be widely used in scenarios such as building wiring, new energy equipment, and mobile electrical equipment that require frequent bending and complex wiring, and has strong practicality. Detailed Implementation

[0019] This invention provides a bend-resistant and crack-resistant bundled insulated wire, which comprises, from the inside out: a multi-wire stranded filling core layer, a shielding layer, and an outer sheath layer; The multi-wire stranded filling core layer consists of multiple stranded wires, with silicone rubber covering the surface of the stranded bundle and filling the gaps between the wires. The single conductor in the multi-wire stranded filler core layer comprises, from the inside out: a conductor, a marking layer, an insulation layer, and a protective layer; the conductor is made of non-uniform diameter copper wire stranded in layers; the marking layer is made of double-sided functionalized polyester tape, one side being a color-printed layer, and the other side being coated with a blend of silane coupling agent and thermoplastic elastomer; the insulation layer is a composite structure with an inner layer of silicone rubber and TPE blend, a middle layer of TPE and nano-boron nitride composite material, and an outer layer of silicone rubber modified TPE; the protective layer is a blend of TPU, modified graphene, and wear-resistant ceramic material; The shielding layer is made of braided metal wire; The outer sheath layer is made of cross-linked polyolefin.

[0020] In this invention, the silicone rubber coating thickness in the multi-wire stranded filler core layer is preferably ≥0.38mm, more preferably ≥0.40mm, and even more preferably ≥0.42mm; the silicone rubber filling density in the multi-wire stranded filler core layer is preferably ≥95%, more preferably ≥96%, and even more preferably ≥97%.

[0021] In this invention, the non-uniform diameter copper wires are preferably stranded in layers by dividing the copper wires into a central layer, a first outer layer, and a second outer layer. The preferred ratio of the number of copper wire strands in the central layer, the first outer layer, and the second outer layer is 1:6:12; The preferred ratio of the copper wire diameters in the central layer, the first outer layer, and the second outer layer is 0.52:0.28:0.15. The twisting pitch ratio of the central layer, the first outer layer and the second outer layer is preferably 8~10:10~12:12~14, more preferably 8~9:10~11:12~13, and even more preferably 9:11:13.

[0022] In this invention, the conductor is also subjected to in-situ annealing and surface roughening treatment in sequence.

[0023] In this invention, the conditions for in-situ annealing include: an annealing temperature preferably of 300-350°C, more preferably of 310-330°C, and even more preferably of 320°C; and a holding time preferably of 10-20 min, more preferably of 12-18 min, and even more preferably of 15 min.

[0024] In this invention, the preferred method for surface micro-roughening is plasma etching. This invention does not limit the plasma etching method; any method well-known in the art can be used to achieve a surface roughening height between 0.02 and 0.1 mm.

[0025] In this invention, the construction scheme for the color printing layer in the identification layer is not limited. Different colors and identification information can be printed according to the wire specifications and uses to facilitate identification during construction.

[0026] In this invention, the silane coupling agent in the marking layer preferably includes an aminosilane coupling agent or a vinylsilane coupling agent. This invention does not impose a specific limitation on the type of silane coupling agent; any type well-known in the art can be used. For example, aminosilane coupling agents include, but are not limited to, KH-550 and KH-560, and vinylsilane coupling agents include, but are not limited to, KH-171.

[0027] In this invention, the thermoplastic elastomer in the marking layer includes styrene-based TPEs. This invention does not specifically limit the type of styrene-based TPE; any type well-known in the art can be used. For example, styrene-based TPEs include, but are not limited to, hydrogenated styrene-butadiene-styrene block copolymers (SEBS) or styrene-butadiene-styrene block copolymers (SBS).

[0028] In this invention, the silane coupling agent in the marking layer preferably accounts for 3 to 10 wt% of the blend of silane coupling agent and thermoplastic elastomer, more preferably 5 to 10 wt%, and even more preferably 8 wt%.

[0029] In this invention, the coating thickness of the silane coupling agent and thermoplastic elastomer blend is preferably 0.02~0.03 mm, more preferably 0.022~0.028 mm, and even more preferably 0.025 mm.

[0030] In this invention, the thickness of the marking layer is preferably 0.05~0.08mm, more preferably 0.06~0.07mm, and even more preferably 0.06mm.

[0031] In this invention, the winding method of the marking layer is not limited, and any solution well known in the art can be used.

[0032] In this invention, the mass fraction of silicone rubber in the inner layer is preferably 60-70%, more preferably 62-66%, and even more preferably 65%; the balance is TPE. The thickness of the inner layer in the insulating layer is preferably 0.2~0.3mm, more preferably 0.23~0.28mm, and even more preferably 0.25mm.

[0033] In this invention, the mass fraction of nano-boron nitride in the middle layer is preferably 1-5%, more preferably 2-4%, and even more preferably 3%; the balance is TPE. The thickness of the middle layer in the insulating layer is preferably 0.1~0.2mm, more preferably 0.12~0.18mm, and even more preferably 0.15mm.

[0034] In this invention, the particle size of the nano-boron nitride is preferably 50~100nm.

[0035] In this invention, a surface hydrophobic additive is also added to the outer layer of the insulating layer; The surface hydrophobic additive preferably includes polytetrafluoroethylene micro powder; The surface hydrophobic additive is preferably 1-2 wt% of the silicone rubber modified TPE, more preferably 1.2-1.8 wt%, and even more preferably 1.5 wt%.

[0036] In this invention, the outer layer thickness is preferably 0.2~0.3 mm, more preferably 0.22~0.28 mm, and even more preferably 0.25 mm.

[0037] In this invention, the modified graphene in the protective layer is preferably 1-5% by mass, more preferably 2-4%, and even more preferably 3% by mass; the wear-resistant ceramic is preferably 3-8% by mass, more preferably 4-6%, and even more preferably 5% by mass; the balance is TPU.

[0038] In this invention, the thickness of the protective layer is preferably 0.3~0.5mm, more preferably 0.35~0.45mm, and even more preferably 0.4mm.

[0039] In this invention, the insulating layer has a raised ridge structure on the surface in contact with the protective layer, and the protective layer has a groove structure on the surface in contact with the insulating layer. The raised ridge structure and the groove structure match to form a mechanical interlocking structure. This invention does not limit the shape or size of the raised ridge structure; any solution well-known in the art can be used.

[0040] In this invention, the braided metal wires in the shielding layer are preferably tin-plated copper wires. This invention does not limit the braiding density of the shielding layer; any method well-known in the art can be used.

[0041] In this invention, the thickness of the outer sheath layer is preferably 0.5~2mm, more preferably 1~1.5mm, and even more preferably 1.5mm.

[0042] In this invention, the sources of various raw materials for the bundled insulated wires are not limited, and commercially available or non-commercially available products well known in the art can be used.

[0043] This invention also provides a method for preparing a bend-resistant and crack-resistant bundled insulated wire, comprising the following steps: (1) Copper wires are mixed and twisted with non-equal diameters to obtain a conductor; double-sided functionalized polyester tape is wrapped around the conductor to obtain a conductor with a marking layer; a co-extrusion process is used to sequentially wrap a silicone rubber and TPE blend, a TPE and nano boron nitride composite material, and silicone rubber modified TPE around the marking layer to obtain a conductor with an insulation layer and a marking layer; finally, a TPU, modified graphene and wear-resistant ceramic blend is wrapped around the insulation layer to obtain a wire. (2) Select multiple wires and bundle them together; send the bundled wire cores after stranding into a filling machine, cover them with silicone rubber and fill them, and after curing, obtain a multi-wire stranded filling core layer; (3) Apply silane coupling agent to the outside of the multi-wire stranded filling core layer, and braid metal wire is used for braiding and covering to obtain a shielding layer; (4) Cross-linked polyolefin is melt-extruded and coated on the outside of the shielding layer. After curing, a bend-resistant and crack-resistant bundled insulated wire is obtained.

[0044] In this invention, in step (1), the conditions of the co-extrusion process include: the co-extrusion temperature is preferably 150~200℃, more preferably 170~190℃, and even more preferably 180℃; the extrusion speed is preferably 5~8m / min, more preferably 6~7m / min, and even more preferably 6m / min.

[0045] In this invention, in step (1), the TPU, modified graphene and wear-resistant ceramic blend material are preferably blended before coating; the blending conditions include: the blending temperature is preferably 150~200℃, more preferably 170~190℃, and more preferably 180℃; the blending speed is preferably 200~300r / min, more preferably 220~280r / min, and more preferably 250r / min.

[0046] In this invention, in step (1), the method of covering the outside of the insulating layer is preferably an extrusion process; the conditions of the extrusion process include: the extrusion temperature is preferably 150~200℃, more preferably 170~190℃, and more preferably 180℃.

[0047] In this invention, in step (2), the filling pressure is preferably 0.3~0.6MPa, more preferably 0.4~0.5MPa, and even more preferably 0.5MPa.

[0048] In this invention, the curing conditions in step (2) include: the curing temperature is preferably 80~100℃, more preferably 90~100℃, and more preferably 100℃; the curing time is preferably ≥10min, more preferably ≥12min, and more preferably ≥15min.

[0049] In this invention, the conditions for melt extrusion in step (4) include: the co-extrusion temperature is preferably 150~200℃, more preferably 170~190℃, and even more preferably 180℃; the extrusion speed is preferably 4~8m / min, more preferably 5~7m / min, and even more preferably 6m / min.

[0050] In this invention, other conditions in the preparation method are not limited, and solutions well known in the art can be used.

[0051] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] Example 1

[0053] This embodiment provides a bend-resistant and crack-resistant bundled insulated wire, the structure of which and its manufacturing method are as follows: 1. Raw material preparation Copper wire: Manufacturer: Jiangxi Copper Industry; Grade: T1R Electrical soft copper wire; Double-sided functionalized polyester tape: Polyester film for electrical insulation, manufactured by Sichuan Dongcai Technology Group Co., Ltd., grade: 6020; one side is printed with color stripes, the other side is a coating layer, the silane coupling agent is KH-550, the thermoplastic elastomer is SEBS6151, manufactured by TSRC, the content of KH-550 in the coating layer is 5wt%; Insulation layer: Inner layer: Silicone rubber ELASTOSIL ® The composition consists of: LR 3170 blended with TPE (manufacturer: LG Chem; grade: KEYFLEX BT1172D), with 60% silicone rubber by mass; middle layer: TPE (manufacturer same as above) and nano-boron nitride (particle size 50~80nm) composite material, with 1% nano-boron nitride by mass; outer layer: silicone rubber modified TPE (silicone rubber blended with TPE, silicone rubber by mass 60%), with 1wt% polytetrafluoroethylene micro powder (manufacturer: 3M; grade: Dyneon TF 9207) added. Protective layer materials: TPU (manufacturer: BASF; grade: Elastollan 1180A), modified graphene (manufacturer: Changzhou Sixth Element; grade: SE1232), wear-resistant ceramics (alumina micro powder C1525G, manufacturer: Zhejiang Zili New Materials; D 50 =1μm), with a mass ratio of TPU:modified graphene:wear-resistant ceramic = 94:1:5; Silicone rubber filler: ELASTOSIL ® LR 3170 (same as the inner layer of the insulation); Shielding layer: tin-plated copper wire, manufacturer: Shenzhen Jinxiuli Weaving Products Co., Ltd., diameter 0.15mm; Outer sheath: Cross-linked polyolefin XLPE, Manufacturer: Borealis, Brand: Visico TM LE4423; 2. Preparation process (1) Preparation of a single conductor: The copper wires are stranded in three layers with non-equal diameters: a central layer, a first outer layer, and a second outer layer. The number of strands is 1:6:12, the diameter ratio is 0.52:0.28:0.15 mm, and the pitch ratio is 8:10:12 D. After stranding, the wires are annealed in situ at 320℃ for 15 minutes, followed by plasma etching for surface micro-roughening to control the surface unevenness height to 0.05~0.08 mm. Double-sided functionalized polyester tape is wrapped around the conductor with the colored printing layer facing outwards. The coating thickness of the silane coupling agent and SEBS blend is 0.02 mm, and the total thickness of the marking layer is 0.05 mm. A three-layer co-extrusion process is adopted, in which the inner, middle and outer layers are sequentially wrapped around the labeling layer; the co-extrusion temperature is 180℃ and the extrusion speed is 6m / min; the inner layer thickness is 0.2mm, the middle layer thickness is 0.1mm and the outer layer thickness is 0.2mm; the outer layer surface is formed into a continuous spiral rib structure through mold design, with a rib height of 0.1mm and a width of 0.2mm; TPU, modified graphene, and wear-resistant ceramics are blended at 180℃ and 250r / min, and then extruded onto the outside of the insulating layer at an extrusion temperature of 180℃. A groove matching the protrusions of the insulating layer is formed on the inner surface of the protective layer, and the thickness of the protective layer is 0.3mm. (2) Bundling and core filling: Seven of the above-prepared wires were selected and bundled together; the bundled wire cores were fed into a filling machine and silicone rubber was injected under a pressure of 0.4 MPa to cover and fill the gaps between the wire cores; the cores were cured at 90°C for 15 min to form a multi-wire stranded filling core layer; the filling density was tested to be 96% and the silicone rubber coating thickness was ≥0.40 mm. (3) Shielding layer braiding: KH-560 silane coupling agent dilution is applied to the outside of the filling core layer, and then tin-plated copper wire is used for braiding with a braiding density of 85%; (4) Outer sheath extrusion: cross-linked polyolefin is melt-extruded at 180°C to cover the outer shielding layer at an extrusion speed of 6 m / min. After cooling and solidification, the finished product is obtained with an outer sheath thickness of 1.0 mm.

[0054] Example 2

[0055] The difference between this embodiment and Embodiment 1 is that: Conductor stranding: The pitch ratio of the center layer, the first outer layer, and the second outer layer is adjusted to 9:11:13 D; Labeling layer: The content of silane coupling agent (KH-560) in the blend is increased to 8 wt%, the coating thickness is 0.025 mm, and the total thickness of the labeling layer is 0.06 mm; Insulation layer: Inner layer: Silicone rubber mass fraction increased to 65%, thickness 0.25mm; Middle layer: Nano boron nitride mass fraction increased to 3%, thickness 0.15mm; Outer layer: Polytetrafluoroethylene micro powder addition increased to 1.5wt%, thickness 0.25mm; Protective layer: 3% modified graphene by mass, 5% wear-resistant ceramic by mass (92% TPU), 0.4mm thickness; Silicone rubber filler: coating thickness ≥ 0.42 mm, filling density 97%, filling pressure 0.5 MPa, curing temperature 100℃, curing time 12 min; Outer sheath layer: 1.5mm thick.

[0056] Example 3

[0057] The difference between this embodiment and Embodiment 1 is that: Conductor stranding: The pitch ratio of the center layer, the first outer layer, and the second outer layer is adjusted to 10:12:14 D; Labeling layer: The content of silane coupling agent KH-171 in the blend is increased to 10wt%, the coating thickness is 0.03mm, and the total thickness of the labeling layer is 0.08mm; Insulation layer: Inner layer: Silicone rubber mass fraction increased to 70%, thickness 0.3mm; Middle layer: Nano boron nitride mass fraction increased to 5%, thickness 0.2mm; Outer layer: Polytetrafluoroethylene micro powder addition increased to 2wt%, thickness 0.3mm; Protective layer: 5% modified graphene by mass, 8% wear-resistant ceramic by mass (87% TPU), 0.5mm thick; Silicone rubber filler: coating thickness ≥ 0.38 mm, filling density 95%, filling pressure 0.6 MPa, curing temperature 80℃, curing time 20 min; Outer sheath layer: 2.0mm thick.

[0058] The performance of the bundled insulated wires prepared in the above three embodiments was tested. The test methods are as follows, and the test results are shown in Table 1.

[0059] (1) Silicone rubber filling density: Method A (density method) in ASTM D2734-09 "Test method for void content of reinforced plastics" was used to determine the density of silicone rubber material and the actual density of the composite core layer, and the filling density was obtained by theoretical calculation. (2) Conductor bending performance: Refer to GB / T 2951.21-2008 "General test methods for insulation and sheath materials of cables and optical cables Part 21: Test methods for elastomer mixtures - ozone resistance test - thermal elongation test - mineral oil immersion test", take the sample and bend it repeatedly in both directions at 90 degrees at room temperature around a round bar with a diameter of 5 times its own. Record the number of bends when visible cracks appear in the sheath or the conductor breaks. (3) Cracking resistance test: Refer to GB / T 2951.31-2008 "General test methods for insulation and sheath materials of cables and optical cables Part 31: Test methods for polyvinyl chloride mixtures - high temperature pressure test - cracking resistance test", wind the conductor on a test bar of specified diameter, put it in a high temperature test chamber at 130℃ and keep it for 1 hour. After cooling, check whether there is cracking on the surface of insulation and sheath.

[0060] (4) Shielding test: Refer to GB / T 17737.5-2013 "Coaxial Communication Cables Part 5: Measurement Method of Cable Shielding Transfer Impedance and Shielding Attenuation", and use the three coaxial method to test the transfer impedance at a frequency of 30MHz.

[0061] Table 1. Test results of Examples 1-3

[0062] In summary, the bend-resistant and crack-resistant bundled insulated wire provided by this invention exhibits excellent overall performance in all three embodiments. By optimizing the conductor structure, employing multi-layer functionalized insulation layers, introducing tightly packed silicone rubber, and setting a mechanical interlocking structure, the problem of traditional bundled wires being prone to cracking and delamination under frequent bending environments is effectively solved, while also taking into account both electrical shielding and mechanical protection performance.

[0063] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A kink-resistant, anti-cracking bundled insulated conductor, characterized by, The bundled insulated wire comprises, from the inside out: a multi-wire stranded filling core layer, a shielding layer, and an outer sheath layer; The multi-wire stranded filling core layer consists of multiple stranded wires, with silicone rubber covering the surface of the stranded bundle and filling the gaps between the wires. The single conductor in the multi-wire stranded filler core layer comprises, from the inside out: a conductor, a marking layer, an insulation layer, and a protective layer; the conductor is made of non-uniform diameter copper wire stranded in layers; the marking layer is made of double-sided functionalized polyester tape, one side being a color-printed layer, and the other side being coated with a blend of silane coupling agent and thermoplastic elastomer; the insulation layer is a composite structure with an inner layer of silicone rubber and TPE blend, a middle layer of TPE and nano-boron nitride composite material, and an outer layer of silicone rubber modified TPE; the protective layer is a blend of TPU, modified graphene, and wear-resistant ceramic material; The shielding layer is made of braided metal wire; The outer sheath layer is made of cross-linked polyolefin.

2. The kink-resistant, anti-cracking bundled insulated conductor of claim 1, wherein, The silicone rubber coating thickness in the multi-wire stranded filler core layer is ≥0.38mm, and the silicone rubber filling density in the multi-wire stranded filler core layer is ≥95%.

3. The kink-resistant, rip-resistant bundled insulated conductor of claim 1, wherein, The non-uniform diameter copper wire layering is specifically described as follows: the copper wire is divided into a central layer, a first outer layer, and a second outer layer. The ratio of the number of copper wire strands in the central layer, the first outer layer, and the second outer layer is 1:6:12, the ratio of the diameter of the copper wires in the central layer, the first outer layer, and the second outer layer is 0.52:0.28:0.15, and the ratio of the twisting pitch of the central layer, the first outer layer, and the second outer layer is 8~10:10~12:12~14.

4. A bend-resistant and crack-resistant bundled insulated wire according to claim 1 or 3, characterized in that, The conductor is also subjected to in-situ annealing and surface roughening treatment in sequence.

5. The bend-resistant and crack-resistant bundled insulated wire according to claim 1, characterized in that, In the labeling layer, the silane coupling agent accounts for 3-10 wt% of the blend of silane coupling agent and thermoplastic elastomer; The thickness of the marking layer is 0.05~0.08mm, and the coating thickness of the silane coupling agent and thermoplastic elastomer blend is 0.02~0.03mm.

6. The bend-resistant and crack-resistant bundled insulated wire according to claim 1, characterized in that, The inner layer contains 60-70% silicone rubber by mass, with the remainder being TPE. The boron nitride nanoparticles in the middle layer have a mass fraction of 1-5%, with the balance being TPE; the particle size of the boron nitride nanoparticles is 50-100 nm. The insulation layer has an inner layer thickness of 0.2~0.3mm, a middle layer thickness of 0.1~0.2mm, and an outer layer thickness of 0.2~0.3mm.

7. A bend-resistant and crack-resistant bundled insulated wire according to claim 1 or 6, characterized in that, In the insulating layer, a surface hydrophobic additive is also added to the outer layer, and the surface hydrophobic additive is 1~2wt% of the mass of the silicone rubber modified TPE.

8. The bend-resistant and crack-resistant bundled insulated wire according to claim 1, characterized in that, In the protective layer, the mass fraction of modified graphene is 1~5%, the mass fraction of wear-resistant ceramic is 3~8%, and the balance is TPU; The thickness of the protective layer is 0.3~0.5mm.

9. A bend-resistant and crack-resistant bundled insulated wire according to claim 1, 6, or 8, characterized in that, The insulating layer has a raised ridge structure on the surface in contact with the protective layer, and the protective layer has a groove structure on the surface in contact with the insulating layer. The raised ridge structure and the groove structure match to form a mechanical interlocking structure.

10. A method for preparing a bend-resistant and crack-resistant bundled insulated wire according to any one of claims 1 to 9, characterized in that, Includes the following steps: (1) Copper wires of different diameters are mixed and twisted together to obtain a conductor; A conductor is coated with a marking layer by wrapping a double-sided functionalized polyester tape around it. Using a co-extrusion process, a blend of silicone rubber and TPE, a composite material of TPE and nano-boron nitride, and silicone rubber-modified TPE are sequentially coated onto the outside of the marking layer to obtain a conductor with an insulating layer and a marking layer; finally, a blend of TPU, modified graphene, and wear-resistant ceramics is coated onto the outside of the insulating layer to obtain a wire. (2) Select multiple wires and bundle them together; send the bundled wire cores after stranding into a filling machine, cover them with silicone rubber and fill them, and after curing, obtain a multi-wire stranded filling core layer; (3) Apply silane coupling agent to the outside of the multi-wire stranded filling core layer, and braid metal wire is used for braiding and covering to obtain a shielding layer; (4) Cross-linked polyolefin is melt-extruded and coated on the outside of the shielding layer. After curing, a bend-resistant and crack-resistant bundled insulated wire is obtained.

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