Bending-resistant flexible cable and preparation method thereof

Abstract

The invention belongs to the technical field of power cables, and particularly relates to an anti-bending flexible cable and a preparation method thereof.The cable sequentially comprises a conductor, an insulating layer, a buffer layer, a shielding layer and a protective layer from inside to outside, the insulating layer is divided into an inner layer, a middle layer and an outer layer in the radial direction, and the inner layer of the insulating layer comprises the following components in parts by weight; 100 parts of crosslinked polyethylene, 6-10 parts of amino-modified photoresponse graphene quantum dots, and 2-4 parts of a plasticizer DOS; 2-3 parts of amino modified photoresponse graphene quantum dots, 100 parts of crosslinked polyethylene and 2-4 parts of a plasticizer DOS; the protective layer comprises the following components in parts by weight; the insulation layer comprises 100 parts of shape memory polyurethane, 15-22 parts of composite microspheres and 0.5-1.0 part of a light stabilizer, and the insulation layer adopts a cross-linked polyethylene, amino modified light response graphene quantum dot gradient distribution and plasticizer system; and three-channel co-extrusion and three-section type ultraviolet curing are matched, so that inner layer under-crosslinking / outer layer over-crosslinking is avoided.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of power cable, and particularly relates to a flexible cable with bending resistance and a preparation method thereof. BACKGROUND

[0002] As a key component for power and signal transmission under dynamic conditions, the bending fatigue resistance of the flexible cable directly determines the reliability and service life of the equipment.

[0003] The traditional conductor is twisted by pure metal wire bundles. When bent, stress concentration occurs between the metal wires due to rigid contact, which easily causes micro-fracture. The insulation layer and protective sleeve are mostly single polymer materials, which are prone to interlayer peeling or material fatigue cracking after repeated bending. Although the soft insulation material improves flexibility, it lacks mechanical strength and is easily punctured by the conductor. Although the hard protective material is wear-resistant, it is poor in flexibility, resulting in large bending resistance of the cable and accelerating the damage of the internal structure. Therefore, it is a technical problem to be solved in the field to develop a flexible cable with high bending fatigue resistance and long service life. SUMMARY

[0004] In view of the above problems in the prior art, the present application provides a flexible cable with bending resistance and a preparation method thereof to solve the problems in the background.

[0005] In order to solve the above technical problems, the present application adopts the following technical scheme: A flexible cable with bending resistance comprises, from inside to outside, a conductor, an insulation layer, a buffer layer, a shielding layer and a protective layer. The conductor is composed of an elastic core and embedded twisted metal wire bundles. The elastic core is a thermoplastic elastomer (thermoplastic polyurethane TPU / styrene-butadiene-styrene block copolymer SBS) containing 0.5-1.5wt% light-responsive crosslinking agent, and a spiral groove is provided on the surface of the elastic core. The groove depth is 0.08-0.12mm, and the tolerance is ±0.005mm. The metal wire bundle is a nickel-plated copper-titanium alloy wire with a single wire diameter of 0.04-0.07mm, which is embedded and twisted in the spiral groove with a twisting pitch of 6-8 times the diameter of the metal wire bundle. The insulation layer is divided into an inner layer, a middle layer and an outer layer along the radial direction. The inner layer contains 100 parts by weight of crosslinked polyethylene, 6-10 parts by weight of amino-modified light-responsive graphene quantum dots with a particle size of 3-8nm, 2-5wt% azobenzene-modified groups and 2-4 parts by weight of plasticizer dioctyl sebacate. The middle layer contains 4-6 parts by weight of amino-modified light-responsive graphene quantum dots. The outer layer contains 2-3 parts by weight of amino-modified light-responsive graphene quantum dots. The insulation layer is formed by gradient co-extrusion and segmented light curing process. The buffer layer is a silicone rubber-barium titanate composite system with a barium titanate content of 5-8wt% and a thickness of 0.3-0.5mm. The interface with the insulation layer is pretreated by plasma. The shielding layer is a tinned copper wire braiding layer, the single wire diameter is 0.07-0.10 mm, and the braiding density is 95%±0.5%; The protective layer contains, by weight parts, 100 parts of shape memory polyurethane, 15-22 parts of composite microspheres, a particle size of 50-100 nm, a graphene quantum dot proportion of 15-20 wt%, a light stabilizer of 0.5-1.0 parts, a composite microsphere axial orientation degree of ≥98%, and a self-repairing efficiency (tearing strength recovery rate) of ≥92% after 30 min of segmented irradiation by 365-405 nm ultraviolet light.

[0006] Further, the spiral groove of the elastic core is formed by ultraviolet laser microprocessing, the laser wavelength is 355 nm, the power is 10-15 W, and the groove wall roughness Ra is ≤0.8 μm; the elastic core breaking elongation is ≥650%, and the crosslinking degree is improved by 40-45% after 365 nm ultraviolet light irradiation.

[0007] Further, the nickel-plated copper-titanium alloy wire is prepared by a "vacuum melting-continuous drawing-electroplating" process, the tensile strength is ≥850 MPa, and the nickel plating layer thickness is 3-5 μm.

[0008] Further, the segmented light curing process parameters of the insulating layer are as follows: the first stage is irradiated at 30-40 mW / cm² for 5-8 s, the second stage is irradiated at 80-100 mW / cm² for 10-12 s, and the third stage is irradiated at 120-150 mW / cm² for 3-5 s; the thickness ratio of the inner layer, the middle layer and the outer layer of the insulating layer is 1:1.2:1, and the total thickness is 0.8-1.2 mm.

[0009] Further, the plasma pretreatment process of the buffer layer is as follows: Ar / O2 mixed gas (volume ratio 3:1) is used, the power is 50-80 W, the processing time is 10-15 s, and the dielectric loss tangent is ≤0.015.

[0010] Further, the composite microspheres are of a core-shell structure, the core is a mixture of hydroxylated graphene quantum dots and dithiodipropionic acid dihydrazide, and the shell is melamine formaldehyde resin; the composite microspheres are axially oriented by magnetic field assistance, and the magnetic field strength is 0.1-0.2 T.

[0011] The application also provides a preparation method of the anti-bending flexible cable. S1. Conductor preparation: S11. Thermoplastic elastomer, light response crosslinking agent (4,4'-bis (azido) benzene) and antioxidant 1010 are added into a double screw extruder in proportion, melt blended at 180-200 °C, and extruded into an elastic core rough blank with a diameter of 0.4-0.6 mm; S12. When the elastic core rough blank is cooled to 80-90℃, a helical groove is processed by using ultraviolet laser (355 nm, 10-15 W), and then the ultraviolet light of 365 nm is used for pre-irradiation for 10-15 s; S13. The metal wire bundle is controlled in tension by a multi-channel tension feedback system, and is twisted into the helical groove at a constant temperature environment of 40-50℃ to obtain a conductor; S2. Preparation of the insulation layer: S21. The inner, middle and outer layer slurries of the insulation layer are respectively prepared, and are deaerated after ultrasonic dispersion for 30-40 min; the three-channel gradient co-extrusion machine is used to coat the conductor periphery, the co-extrusion machine is controlled in three sections (inner layer 170-180℃, middle layer 160-170℃, outer layer 150-160℃), and the near-infrared online detection module is used for real-time adjustment of the feeding speed of each channel; S22. After co-extrusion, three-stage ultraviolet curing is immediately used: 30-40 mW / cm² irradiation for 5-8 s→80-100 mW / cm² irradiation for 10-12 s→120-150 mW / cm² irradiation for 3-5 s, and then drying in an oven at 85-95℃ for 1-2 h to obtain an insulated wire core; S3. Buffer layer coating: S31. The surface of the insulated wire core is treated by Ar / O2 plasma at 50-80 W for 10-15 s; S32. The silicone rubber-barium titanate composite slurry is coated on the periphery of the treated insulated wire core by an extruder, the extrusion temperature is 130-140℃, the pulling speed is 4-6 m / min, and the cooling is set; S4. Shielding layer weaving: S41. The weaving of the tinned copper wire is controlled by using a double-shaft servo synchronous system, and the synchronization error between the pulling speed and the spindle speed is ≤0.1%; S42. The weaving density is detected online by a high-speed camera, and the spindle speed is automatically adjusted to ensure that the weaving density is 95%±0.5%, thereby obtaining a shielding wire core; S5. Preparation of the protective layer: S51. The shape memory polyurethane, composite microspheres and light stabilizer are added into a supercritical CO2 reactor (45℃, 18 MPa), and are mixed for 40-50 min under ultrasonic assistance (20 kHz, 300 W); S52. The mixed system is coated on the periphery of the shielding wire core by an extruder, a permanent magnet array (magnetic field strength 0.1-0.2 T, length 50-80 mm) is arranged at the outlet section of the extrusion die, the extrusion temperature is 175-190℃, the screw rotation speed is 30-40 r / min, and the cooling is set; S6. Post-processing: S61. First, the conductor elastic core is activated by using the ultraviolet light of 365 nm (80-100 mW / cm²) for irradiation for 10-15 s; S62. Again irradiate with 405nm ultraviolet light (100-120mW / cm²) for 10-15s, activate the light response components of the insulation layer and the protective layer, and complete the preparation.

[0012] Further, in step S13, the multi-channel tension feedback system dynamically adjusts the wire bundle pay-off speed through a servo motor.

[0013] Further, in step S21, the near-infrared online detection module is linked with the PLC system, the response time of the feed screw speed adjustment is ≤0.5s, and the concentration deviation of the graphene quantum dots of each layer of the insulation layer is ≤0.3wt%.

[0014] Further, in step S52, the magnetic field strength of the permanent magnet array is monitored online by a magnetometer, and the distance between the permanent magnets is adjusted in real time to ensure that the axial orientation degree of the composite microspheres is ≥98%.

[0015] Compared with the prior art, the present application has the following beneficial effects: 1. The insulation layer adopts a "cross-linked polyethylene + amino-modified light-responsive graphene quantum dot gradient distribution + plasticizer" system; combined with three-channel co-extrusion and three-stage ultraviolet curing, the risk of breakdown caused by electric field concentration is avoided. 2. The conductor adopts a "thermoplastic elastomer elastic core containing 0.5-1.5wt% light-responsive cross-linking agent + spiral groove embedded nickel-plated copper-titanium alloy wire bundle" design: the elastic core can absorb more than 70% of the bending stress, the light-responsive cross-linking agent can increase the cross-linking degree by 40-45%, and the spiral groove can avoid collapse; the metal wire bundle is embedded and arranged to reduce rigid contact wear. Combined with the quantum dot gradient distribution of the insulation layer and the 0.1-0.2T magnetic field axial orientation of the composite microspheres in the protective layer, the bending resistance life of the cable is much longer than that of traditional cables, meeting the dynamic wiring needs of industrial robots, mobile devices, etc. 3. The shielding layer is a tinned copper wire braided layer, which has good shielding effectiveness and a tin plating layer that prevents oxidation, solving the problem of bare copper wire corrosion; the protective layer contains shape memory polyurethane, core-shell structure composite microspheres and light stabilizer 770, and the performance retention rate is high after 1000h of ultraviolet aging, suitable for harsh working conditions such as outdoor and humid environments. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a structural schematic diagram of the anti-bending flexible cable of the present application; Figure 2 is a schematic diagram of the insulation layer of the anti-bending flexible cable of the present application; Figure 3 is a flow chart of the preparation method of the insulation of the anti-bending flexible cable of the present application; The reference signs in the drawings of the specification include: 1, conductor; 2, insulation layer; 21, inner layer of insulation layer; 22, middle layer of insulation layer; 23, outer layer of insulation layer; 3, buffer layer; 4, shielding layer; 5, protective layer. DETAILED DESCRIPTION

[0017] In order for those skilled in the art to better understand the present application, the technical solutions of the present application are further described below in conjunction with the accompanying drawings and examples.

[0018] The conventional conductor adopts pure metal wire bundle to be twisted, and stress concentration is generated between the metal wires due to rigid contact when being bent, and micro-fracture is prone to occur; the insulation layer and the protective sleeve are mostly single polymer material, and interlayer peeling or material fatigue cracking is prone to occur after repeated bending; although the soft insulation material improves flexibility, the mechanical strength is insufficient, and the conductor is prone to be punctured; although the hard protective material is wear-resistant, the flexibility is poor, resulting in large bending resistance of the cable and accelerating damage to the internal structure; therefore, it is a technical problem to be solved in the field to develop a flexible cable with high bending fatigue resistance and long service life The present application provides an anti-bending flexible cable, which comprises a conductor, an insulation layer, a buffer layer, a shielding layer and a protective layer from inside to outside, characterized in that the conductor comprises an elastic core and a metal wire bundle twisted around the periphery of the elastic core. The insulation layer is divided into an inner layer, a middle layer and an outer layer along the radial direction, wherein the inner layer of the insulation layer comprises the following components by weight: 100 parts of cross-linked polyethylene, 6-10 parts of amino-modified light-responsive graphene quantum dots and 2-4 parts of plasticizer DOS; The middle layer of the insulation layer comprises the following components by weight: 4-6 parts of amino-modified light-responsive graphene quantum dots, 100 parts of cross-linked polyethylene and 2-4 parts of plasticizer DOS; The outer layer of the insulation layer comprises the following components by weight: 2-3 parts of amino-modified light-responsive graphene quantum dots, 100 parts of cross-linked polyethylene and 2-4 parts of plasticizer DOS; The amino-modified light-responsive graphene quantum dots are functional nanomaterials obtained by performing amino chemical modification on graphene quantum dots (basic carrier) and endowing the graphene quantum dots with light-responsive characteristics. The graphene quantum dots provide mechanical / electrical basis, the amino modification solves the compatibility problem with the matrix, and the light-responsive characteristics adapt to the segmented light-curing process of the insulating layer, so that the triple effects of "enhanced tear resistance + auxiliary crosslinking + stable dispersion" are finally achieved in the insulating layer. Graphene quantum dots (GQDs) are nanoscale fragments of graphene (usually 3-8 nm in size, spherical or flaky, with excellent properties of graphene, but due to quantum size effect, additional optical response ability; the atomically dense structure makes the tensile strength reach 130 GPa, and when added to the crosslinked polyethylene matrix, it can disperse bending stress like "nanometer steel bar", which is the key to the insulating layer tear strength ≥40 MPa; the nanoscale size enables it to absorb specific wavelength ultraviolet light (365-405 nm, matching the segmented light-curing wavelength), providing the basis for "light response"; the amino-modified light-responsive graphene quantum dots are formed by grafting amino groups (-NH2) onto the surface of graphene quantum dots through chemical methods (such as ammonia reduction method and amine coupling reaction); the amino group (polar group) can form hydrogen bonds with the hydroxyl group (-OH) and ester group (-COO-) in the crosslinked polyethylene matrix, avoiding the agglomeration of quantum dots in the slurry, and the amino modification can further reduce the agglomeration rate; the modified quantum dots are not easy to "channel layer" in the molten slurry, ensuring that the concentration deviation of the inner layer (6-10 wt%), middle layer (4-6 wt%) and outer layer (2-3 wt%) is ≤0.2 wt% during gradient co-extrusion; the amino group can react with the active free radicals of crosslinked polyethylene during light-curing process, indirectly improving the crosslinking efficiency (making the inner layer crosslinking degree reach 75%-85% faster). The amino-modified graphene quantum dots will undergo "photo-induced electron transfer" under 365-405 nm ultraviolet light (the core wavelength of segmented light-curing): after absorbing light energy, the electrons of the surface amino group are excited and can be transferred to the crosslinked polyethylene molecular chain or photoinitiator, accelerating the crosslinking reaction; the inner layer (high addition amount 6-10 wt%): under high light intensity (120-150 mW / cm²), the light response of quantum dots is more significant, which assists the rapid and deep crosslinking of the inner layer and strengthens the tear resistance; the middle / outer layer (low addition amount): under low light intensity (30-100 mW / cm²), the response is mild, avoiding excessive crosslinking leading to the embrittlement of the outer layer; without light: the quantum dots only play a mechanical strengthening role and do not interfere with the storage or co-extrusion process of the slurry (such as good stability at 170-180°C inner layer temperature control).

[0019] The protective layer comprises the following components by weight: 100 parts of shape memory polyurethane, 15-22 parts of composite microspheres, and 0.5-1.0 parts of light stabilizer.

[0020] The shape memory polyurethane is a kind of polyurethane polymer material with "light / thermal stimulus response shape memory function", which can recover from the "temporary deformation" caused by bending to the initial structure morphology under 405nm ultraviolet light (corresponding to the post-processing step S62 "405nm ultraviolet light irradiation activation") or a specific temperature, and has excellent compatibility with composite microspheres and light stabilizers; ordinary polyurethane has good flexibility, but is prone to irreversible deformation (such as wrinkles and cracks) after repeated bending and cannot recover automatically; while the shape memory polyurethane can recover to the original shape by light activation, avoiding deformation accumulation leading to failure of the protective layer; the amino and ester groups in the molecular structure of the shape memory polyurethane can form hydrogen bonds with the hydroxyl groups in the shell layer (melamine formaldehyde resin) of the composite microspheres, and at the same time, the dispersion of the light stabilizer 770 is compatible, ensuring the uniformity of the overall components of the protective layer and avoiding delamination.

[0021] The composite microspheres have a core-shell structure, and the parameters and compositions are as follows: size: particle size 50-100 nm; Core layer: mixture of hydroxylated graphene quantum dots (15-20wt%) and dithiodipropionic acid dihydrazide (containing a disulfide bond, a self-repairing active component), after 365-405nm ultraviolet light irradiation for 30min, the disulfide bond breaks and recombines, the tear strength recovery rate of the protective layer is ≥92%, and the microcracks (width ≤5μm) caused by bending can be repaired; Shell layer: melamine formaldehyde resin (rigid support layer), the shell layer melamine formaldehyde resin can block external water vapor and oxygen, and slow down the oxidation aging of the protective layer matrix (shape memory polyurethane); Orientation: axial orientation (along the length direction of the cable) is achieved by 0.1-0.2T magnetic field assistance during preparation, and the orientation degree is ≥98%.

[0022] The shell layer (melamine formaldehyde resin) can prevent the loss of the disulfide bond component in the core, and at the same time provide rigid support; the hydroxylated graphene quantum dots (high mechanical strength) in the core can specifically enhance the tear resistance of the protective layer, and the disulfide bond of dithiodipropionic acid dihydrazide can break and recombine under ultraviolet light to realize self-repair; when the cable is bent, the stress is transmitted along the length direction, and the axial arrangement of the microspheres can maximize the dispersion of the bending stress (avoiding stress concentration leading to cracking), and the anti-bending fatigue life is improved by more than 40% compared with random dispersion.

[0023] In the dynamic bending working condition of the cable, the stress is mainly transmitted along the length direction (axial direction) (such as the bending force of the cable is distributed along the axial direction when the industrial robot joint swings or the equipment moves), if the composite microspheres are randomly dispersed: the amount of core layer hydroxylated graphene quantum dots (high mechanical strength) cannot be arranged in the stress direction, and is easy to form "stress concentration points" on the inside / outside of the bending, causing the local tearing of the protective layer, axial orientation (along the length direction of the cable): the "axial orientation degree of the composite microspheres is ≥98%" after the magnetic field assistance, in any unit volume (such as 1 mm3) of the protective layer, the included angle between the long axis of at least 98% of the composite microspheres and the length direction (axial direction) of the cable is ≤5°, only less than 2% of the microspheres deviate slightly (included angle > 5°) or arrange randomly due to dispersion error, which can be understood as "more than 98% of the 100 microspheres are neatly oriented in the extension direction of the cable, only 1-2 microspheres are slightly arranged", and the whole presents a highly unified axial arrangement state, which is realized through 0.1-0.2T magnetic field assistance. When the protective layer generates microcracks (extend along the radial direction or the axial direction) due to bending, the cracks at any position can contact the disulfide bond component, and after irradiation by 365-405 nm ultraviolet light, the disulfide bond breaks and recombines. The graphene quantum dots can evenly disperse the axial bending stress like "axial nanometer steel bars", avoiding local stress from being too high to cause cracking; at the same time, the core layer disulfide bond (self-repairing active component) is also evenly distributed along the axial direction, and when activated by subsequent ultraviolet light, it can cover the microcracks comprehensively, ensuring the self-repairing efficiency, the core layer of the composite microspheres containing hydroxylated graphene quantum dots has weak magnetism, and sufficient magnetic field force is needed to drive the directional arrangement. If the magnetic field strength <0.1T (such as 0.05T), the magnetic field force is not enough to overcome the van der Waals force between the microspheres, and the orientation degree will decrease to below 80%, which cannot form effective axial arrangement, and the anti-tearing performance of the protective layer decreases, if the magnetic field strength >0.2T (such as 0.3T), the magnetic field force is too strong, which can cause the microspheres to attract each other and form agglomerates with a diameter >1μm (the particle size of the microspheres is required to be 50-100nm). The agglomerates not only destroy the continuity of the protective layer, but also form "dielectric / mechanical defects" at the local position - such as the self-repairing component is missing in the agglomerate (the disulfide bond is concentrated in the agglomerate), which causes the cracks to be unable to be repaired; at the same time, the agglomerates can also scratch the inner shielding layer, causing the shielding efficiency to fluctuate. The axially oriented composite microspheres can complement the "light-induced shape recovery" function of the shape memory polyurethane - after bending, the shape memory polyurethane restores the original shape, and the axially oriented microspheres simultaneously disperse the elastic recovery stress, avoiding the accumulation of deformation; the 0.1-0.2T magnetic field orientation process does not affect the function of the light stabilizer 770 (the light stabilizer 770 "does not react with the composite microspheres"), and when activated by subsequent ultraviolet light, it can not only ensure the self-repairing / shape memory functions, but also inhibit aging through the light stabilizer, prolonging the service life of the protective layer.

[0024] Light stabilizer 770 (Hindered amine HALS, Hindered amine light stabilizer), the amount of addition is 0.5-1.0 parts by weight, the chemical property is stable, does not absorb 365-405 nm ultraviolet light (avoid interfering with the light activated self-repair, shape memory function), and does not react with shape memory polyurethane, composite microspheres. Ultraviolet light can cause the molecular chain of shape memory polyurethane to break (inducing embrittlement, flexibility decrease), and also can destroy the double sulfur bond of the core layer of the composite microspheres (lose self-repair function); ordinary light stabilizers (such as ultraviolet absorbers) may absorb 365-405 nm ultraviolet light, interfere with the light activation process of the post-processing step; and light stabilizer 770 inhibits aging by "capturing free radicals", without affecting the function of the light responsive component.

[0025] In an embodiment, the buffer layer is a silicone rubber-barium titanate composite system, with a thickness of 0.3-0.5 mm, and the interface thereof in contact with the insulating layer is pretreated by plasma. The buffer layer uses methyl vinyl silicone rubber as the matrix, and barium titanate particles as the functional filler uniformly dispersed in the matrix. The mass fraction of barium titanate on the side of the buffer layer close to the insulating layer is 7-8 wt%, and the mass fraction of barium titanate on the side of the buffer layer close to the shielding layer is 5-6 wt%. The dielectric constant of the buffer layer decreases from the side of the insulating layer to the side of the shielding layer, forming a micro-graded distribution of the dielectric constant along the radial direction.

[0026] It is explained that the traditional buffer layer matrix (such as ordinary nitrile rubber) is not flexible enough and is prone to hardening and cracking after repeated bending. The molecular chain of methyl vinyl silicone rubber contains flexible Si-O bonds, with a Shore hardness of only 30-50A at room temperature and an elongation at break of ≥500%. It can produce elastic deformation with the cable bending, effectively absorbing the bending stress between the insulating layer and the shielding layer (reducing stress transmission loss by more than 40%), while having excellent high and low temperature resistance (stable at -60-200°C), suitable for cable use in multiple working conditions.

[0027] The dielectric constant of the insulating layer (crosslinked polyethylene-based) is about 2.3-2.5, and the dielectric constant of the shielding layer (tinned copper wire) is close to infinity. Direct contact between the two will cause "electric field concentration" due to the sudden change in dielectric constant (the local field strength can be 3-5 times the average field strength), which is prone to cause breakdown of the insulating layer. Barium titanate is a high-dielectric filler (dielectric constant ≥1000). By "high content (7-8 wt%) on the side close to the insulating layer and low content (5-6 wt%) on the side close to the shielding layer", the dielectric constant of the buffer layer is gradually reduced from 30-40 to 15-20 along the radial direction, forming a dielectric constant transition zone from "insulating layer → buffer layer → shielding layer", avoiding electric field concentration. If barium titanate is uniformly distributed, the dielectric constant of the buffer layer is single, and the dielectric sudden change between the insulating layer and the buffer layer cannot be eliminated.

[0028] If the interface between the buffer layer and the insulating layer is not firmly combined, interlayer peeling is likely to occur when bending (peeling strength < 1.5 N / mm in traditional process); the surface of the insulating layer is treated by Ar / O2 plasma (volume ratio 3:1, power 50-80 W, time 10-15 s), which can achieve two key functions: etching the surface of the insulating layer (roughness Ra increases from 0.2 μm to 0.8-1.0 μm), and increasing the contact area between the buffer layer and the insulating layer; active groups such as hydroxyl (-OH) and carboxyl (-COOH) are introduced on the surface of the insulating layer, which chemically bond with the silicon hydroxyl (-SiOH) of the methyl vinyl silicone rubber, so that the interfacial peeling strength is increased to ≥3.0 N / mm, avoiding interlayer peeling.

[0029] The preparation method of the silicone rubber-barium titanate composite system comprises the following steps: Pre-treatment: insulating layer interface plasma treatment equipment: low-temperature plasma treatment machine (equipped with Ar / O2 gas mixing system); process parameters: Ar / O2 volume ratio 3:1, treatment power 50-80 W, treatment time 10-15 s, treatment distance (nozzle to the surface of the insulating layer) 5-8 mm; etching the surface of the insulating layer and introducing active groups to prepare for the subsequent combination of the buffer layer.

[0030] Preparation of composite slurry: prepare gradient barium titanate slurry in batches High-content slurry (corresponding to the side of the buffer layer close to the insulating layer, 7-8 wt% barium titanate): take 100 parts by weight of methyl vinyl silicone rubber, 7-8 parts by weight of barium titanate, and 1.5-2.0 parts by weight of vulcanizing agent (such as dicumyl peroxide), add it into a high-speed mixer (rotation speed 1000-1200 r / min), mix at 80-90°C for 30-40 min to form a uniform slurry; Low-content slurry (corresponding to the side of the buffer layer close to the shielding layer, 5-6 wt% barium titanate): keep the amount of methyl vinyl silicone rubber and vulcanizing agent unchanged, adjust the amount of barium titanate to 5-6 parts by weight, and prepare the slurry according to the same mixing process; transfer the two kinds of slurry into a 20 kHz, 300 W ultrasonic device respectively, and ultrasonic dispersion for 20-30 min to ensure uniform dispersion of barium titanate particles (no agglomerates with particle size > 5 μm).

[0031] Gradient extrusion coating: double-channel gradient extruder (equipped with independent temperature control system and coaxial mold, two channels respectively conveying high-content and low-content slurry); extrusion temperature: 130-140°C (adapted to the melt flowability of methyl vinyl silicone rubber to avoid premature decomposition of the vulcanizing agent); pulling speed: 4-6 m / min (synchronous with the co-extrusion pulling speed of the insulating layer to avoid uneven thickness of the buffer layer); the inner channel of the coaxial mold conveys high-content slurry (close to the insulating layer), and the outer channel conveys low-content slurry (close to the shielding layer), the channel cross-sectional area ratio is 1:1.2, which ensures the total thickness of the buffer layer to be 0.3-0.5 mm; Cooling and setting: the extruded buffer layer immediately enters a 25-30℃ cooling water tank (cooling length 1-1.5m), and is cooled to a surface temperature ≤50℃, fixing the gradient structure and shape.

[0032] Post-vulcanization: the cooled and set cable is sent into a hot air circulating oven, and is vulcanized at 150-160℃ for 2-3h, so that the methyl vinyl silicone rubber is fully crosslinked, and the barium titanate particles are firmly combined with the matrix, finally forming a silicone rubber-barium titanate composite buffer layer with a gradient distribution of dielectric constant.

[0033] In an embodiment, the shielding layer is a tinned copper wire braided layer. The cable is susceptible to external electromagnetic interference (EMI) and radio frequency interference (RFI) in power / signal transmission, and the shielding layer needs to have high electrical conductivity to "ground and lead away interference current" - the volume resistivity of copper is only 1.72×10 -8 Ω·m (much lower than that of aluminum, iron and other metals), which can efficiently absorb and conduct interference signals, is the optimal base material selection for realizing "low interference transmission", and is suitable for the functional positioning of the cable "stable transmission". Bare copper wire is easily oxidized to form copper oxide (resistivity increases sharply, and shielding performance decreases) in humid and high-temperature environments, while tin has excellent chemical stability: a dense protective film can be formed on the surface of the copper wire by the tin plating layer, which prevents air and water vapor from contacting the copper and prevents oxidation and rusting. At the same time, tin has good ductility, and the plating layer is not prone to cracking during subsequent braiding and bending, ensuring stable long-term shielding performance and meeting the needs of the cable "for use in multiple environments". The braided layer is formed by interlacing multiple thin copper wires (single wire diameter 0.07-0.10mm), and the single wires can slide slightly along the interlacing gap during bending, following the overall deformation of the cable (no risk of breaking when the bending radius is ≤10 times the cable diameter), avoiding the problem of "easy breakage and shielding failure" of traditional metal foils during bending. The buffer layer (silicone rubber-barium titanate system) is a flexible elastomer, and the mesh structure of the braided layer can fully adhere to the surface of the buffer layer, and the two layers deform synchronously during bending, reducing the risk of interlayer peeling and controlling the "braiding density 95%±0.5%": balancing the shielding effect and flexibility.

[0034] In an embodiment, the elastic core is a thermoplastic elastomer containing 0.5-1.5wt% of a light-responsive crosslinking agent. The metal wire bundle is a nickel-plated copper-titanium alloy wire with a single wire diameter of 0.04-0.07mm and a twisting pitch of 6-8 times the diameter of the metal wire bundle.

[0035] It is illustrated that the traditional conductor core is mostly rigid metal or pure rubber, the former is easy to produce stress concentration when bending, and the latter is difficult to process; and the thermoplastic elastomer (TPU / styrene-butadiene-styrene block copolymer SBS) has both "rubber elasticity" and "plastic hot workability" - at room temperature, the molecular chain soft segment freely moves to present high flexibility (elongation at break ≥ 650%), which can absorb the stress of metal wire bundle twisting and cable bending; at high temperature (180-200℃), it can be melt extruded to meet the process requirements of the spiral groove processing of the elastic core, if no photoresponsive crosslinking agent is added, the elastic core is easy to have "permanent deformation" (such as spiral groove collapse) after long-term bending, and cannot stably support the metal wire bundle; if the addition amount is less than 0.5wt%, the crosslinking degree is insufficient (the crosslinking degree is increased by less than 30% after 365nm ultraviolet light irradiation), and the anti-deformation ability of the elastic core is weak; If the addition amount is greater than 1.5wt%, the crosslinking degree is too high, the rigidity of the elastic core increases (Shore hardness > 75A), and the cable bending resistance increases. The high elasticity of the elastic core can absorb more than 70% of the radial stress when the cable is bent, avoiding micro-fracture of the metal wire bundle (nickel-plated copper-titanium alloy wire) due to rigid contact, after 10-15s of 365nm ultraviolet light pre-irradiation, the photoresponsive crosslinking agent activates crosslinking, the hardness of the elastic core increases from 60A to 75A, and the deformation amount of the spiral groove decreases from 15% to less than 5%, which can stably embed the metal wire bundle (avoiding wire bundle slipping during twisting); subsequent post-processing ultraviolet irradiation can further strengthen the support.

[0036] The core composition of the elastic core is as follows: the type of the thermoplastic elastomer matrix (main body) is one of thermoplastic polyurethane (TPU) or styrene-butadiene-styrene block copolymer (SBS); TPU: the molecular chain contains "hard segment (polyurethane segment, providing basic strength) + soft segment (polyether / polyester segment, providing elasticity)", the temperature resistance range is -50-150℃, which is suitable for extreme working conditions; SBS: composed of "rigid styrene segment (S segment, physical crosslinking point) + flexible butadiene segment (B segment, elasticity source)", the flexibility is optimal when the butadiene segment content is 30-40%, and the processing temperature is lower (160-180℃).

[0037] The photoresponsive crosslinking agent is 4,4'-bis(azido)benzene; it contains azido (-N3) photoactive group, which is broken to generate free radicals under 365nm ultraviolet light irradiation, and crosslinking reaction occurs with the molecular chain of TPU / SBS to form a three-dimensional network structure, realizing performance regulation; the addition amount is 0.5-1.5wt% (relative to the mass of the thermoplastic elastomer matrix).

[0038] In an embodiment, the thickness ratio of the inner layer, the middle layer and the outer layer of the insulation layer is 1:1.2:1, and the total thickness is 0.8-1.2 mm. The preparation method of the insulation layer comprises the following steps: preparing the inner layer, the middle layer and the outer layer slurry of the insulation layer, ultrasonic dispersion for 30-40 min and then defoaming; using a three-channel co-extrusion machine, segmenting the temperature control at 170-180℃ for the inner layer, 160-170℃ for the middle layer and 150-160℃ for the outer layer, synchronously coating the three layers of slurry on the conductor and then shaping by cold water at 20-25℃; after the cold water shaping, using three-stage ultraviolet light curing, sequentially irradiating at 30-40 mW / cm² for 5-8 seconds, 80-100 mW / cm² for 10-12 seconds and 120-150 mW / cm² for 3-5 seconds; finally, drying the insulation wire core by hot air at 85-95℃ for 1-2 hours.

[0039] It is explained that if the total thickness of the insulation layer is <0.8 mm: the insulation layer is too thin to meet the insulation requirement of “breakdown field strength ≥ 35 kV / mm” (easy to cause breakdown due to insufficient thickness and concentrated electric field); if the total thickness is >1.2 mm: the insulation layer is too thick, which will increase the overall diameter of the cable and the bending resistance (contrary to the design goal of “flexible cable”, the bending radius needs to be increased by more than 20%, which cannot adapt to dynamic working conditions); the thickness ratio of the inner layer (anti-tearing), the middle layer (transition) and the outer layer (flexibility) makes the “anti-tearing strength-flexibility” of the insulation layer along the radial direction present a gentle transition (the tearing strength of the inner layer ≥ 45 MPa, the outer layer ≥ 30 MPa and the middle layer ≥ 38 MPa), avoiding the bending delamination (interlayer peeling strength ≥ 3.0 N / mm, much higher than the 1.5 N / mm of ordinary equal-thickness structure) caused by performance mutation of the traditional “equal-thickness three-layer”. Under the control of the total thickness, the breakdown field strength of the insulation layer is stable ≥ 35 kV / mm (meeting the power transmission insulation requirement), and at the same time, the overall bending radius of the cable can be reduced to 8-10 times of the diameter (ordinary thick insulation cable needs 12-15 times), which adapts to dynamic bending working conditions (such as industrial robot joints and mobile device wiring). The amino-modified light-responsive graphene quantum dots are easy to agglomerate due to van der Waals force, and if not uniformly dispersed, it will cause local quantum dots to be excessive (embrittlement) or insufficient (poor anti-tearing / insulation). If there are bubbles in the slurry, “bubble defects” will be formed after co-extrusion, directly reducing the breakdown field strength (bubble electric field concentration, easy to cause breakdown). 20 kHz ultrasonic dispersion can break the agglomeration, making the uniformity of the quantum dots ≥ 90% and the concentration deviation of each layer ≤ 0.3 wt%. After defoaming, there are no visible bubbles in the slurry, and the insulation layer formed by co-extrusion has no bubble defects, and the qualified rate of the breakdown field strength is increased to more than 98% (when not defoamed, the qualified rate is only 75%) The inner layer slurry has the highest quantum dot content (6-10 parts) and a viscosity 30%-50% higher than the middle and outer layers. It requires a higher temperature (170-180℃) to reduce viscosity and ensure uniform flow during extrusion (avoiding fluctuations in inner layer thickness). The outer layer slurry has the lowest quantum dot content (2-3 parts) and low viscosity. If the temperature is too high (>160℃), it will lead to over-melting and embrittlement after cooling (violating the "flexible" positioning of the outer layer). The middle layer uses a transition temperature (160-170℃) to eliminate the temperature difference between the inner and outer layers and promote the diffusion and fusion of molecular chains at the three-layer interface (avoiding interlayer delamination). After co-extrusion, the slurry is in a molten viscous flow state at 150-180℃. If it cools naturally, the high-viscosity inner layer slurry and the low-viscosity outer layer slurry are prone to "layering" due to the difference in flowability (disordered quantum dot distribution, destroying the 1:1.2:1 thickness ratio and gradient concentration). The molten slurry is prone to deformation due to tension during traction, resulting in eccentric insulation layer (uneven thickness). Cold water at 20-25℃ can rapidly solidify the slurry surface through rapid heat exchange (cooling rate ≥10℃ / s) (surface hardness reaches Shore D30), locking in the three-layer structure; after cold water setting, the gradient structure of the insulation layer (thickness ratio, quantum dot concentration) has no layer migration, and the eccentricity is ≤0.05mm (far lower than the industry standard of 0.1mm). The cured structure provides "rigid support" for subsequent photocuring, avoiding uneven cross-linking caused by material flow during light irradiation. Outer layer: requires high flexibility, and the degree of cross-linking needs to be controlled at 30% to 40% (over-cross-linking will cause embrittlement). Therefore, it is irradiated with low light intensity (30 to 40 mW / cm²) for a short time (5 to 8 s) to achieve only preliminary cross-linking. Middle layer: requires "balance between tear resistance and flexibility", and the degree of cross-linking needs to be 60% to 70%. Therefore, it is irradiated with medium light intensity (80 to 100 mW / cm²) for a medium time (10 to 12 s) to achieve full cross-linking. Inner layer: requires "high tear resistance and voltage resistance", and the degree of cross-linking needs to be 75% to 85%. Since the inner layer is located at the innermost edge, the light needs to penetrate the middle and outer layers. Therefore, it is irradiated with high light intensity (120 to 150 mW / cm²) for a short time (3 to 5 s) to ensure deep cross-linking and avoid excessive cross-linking of the middle and outer layers.

[0040] The slurry contains the plasticizer DOS (2-4 parts). DOS is the abbreviation for dioctyl sebacate, CAS number 122-62-3, molecular formula C 26 H 50 O4 is a colorless or pale yellow transparent oily liquid. After co-extrusion and photocuring, trace amounts of low-boiling-point solvents (such as impurities in DOS) may remain. If not removed, solvent evaporation during long-term use will cause the insulation layer to shrink and produce microcracks. Hot air at 85-95℃ can promote further cross-linking of unreacted quantum dots and cross-linked polyethylene molecular chains (increasing the degree of cross-linking by 5%-10%), reducing internal stress.

[0041] The application further provides a preparation method of the anti-bending flexible cable. S1. Conductor preparation: S11. Thermoplastic elastomer, light-responsive crosslinking agent and antioxidant 1010 are added into a double-screw extruder in proportion, melt-blended at 180-200 DEG C, and extruded into an elastic core rough blank with a diameter of 0.4-0.6 mm; S12. When the elastic core rough blank is cooled to 80-90 DEG C, a spiral groove is processed by using ultraviolet laser, and then the spiral groove is pre-irradiated by 365 nm ultraviolet light for 10-15 s; S13. Metal wire bundles are embedded and twisted in the spiral groove in a constant temperature environment of 40-50 DEG C to obtain a conductor; S2. Insulating layer preparation: S21. Inner, middle and outer insulating layer slurries are respectively prepared, and are deaerated after ultrasonic dispersion for 30-40 min; the conductor is coated outside by using a three-channel gradient co-extruder, and is shaped by cold water at 20-25 DEG C after extrusion, and the co-extruder is controlled in three sections, wherein the temperature of the inner layer is controlled at 170-180 DEG C, the temperature of the middle layer is controlled at 160-170 DEG C, and the temperature of the outer layer is controlled at 150-160 DEG C; S22. Three-stage ultraviolet light curing is adopted: 30-40 mW / cm² is irradiated for 5-8 s, 80-100 mW / cm² is irradiated for 10-12 s, and 120-150 mW / cm² is irradiated for 3-5 s, and then the insulating wire core is dried in an oven at 85-95 DEG C for 1-2 h; S3. Buffer layer coating: S31. The surface of the insulating wire core is treated by Ar / O2 plasma; S32. The silicone rubber-barium titanate composite slurry is coated outside the treated insulating wire core by using an extruder, the extrusion temperature is 130-140 DEG C, the pulling speed is 4-6 m / min, and the cooling shaping is performed; S4. Shielding layer weaving: S41. The tinned copper wire is woven by using a double-shaft servo synchronous system to obtain a shielding wire core; S5. Protective layer preparation: S51. Shape memory polyurethane, composite microspheres and light stabilizer are added into a supercritical CO2 reaction kettle, and are ultrasonically mixed for 40-50 min; S52. The mixed system is coated outside the shielding wire core by using an extruder, a permanent magnet array is arranged at the outlet section of the extrusion die, the extrusion temperature is 175-190 DEG C, and the cooling shaping is performed; S6. Post-processing: S61. First, the conductor elastic core is activated by irradiating 365 nm ultraviolet light for 10-15 s; S62. Again irradiate with 405 nm ultraviolet light for 10-15 s to activate the light responsive components of the insulation layer and the protective layer, and complete the preparation Example 1 provides a bending-resistant flexible cable, which comprises, from inside to outside, a conductor, an insulation layer, a buffer layer, a shielding layer, and a protective layer. The conductor: the elastic core is TPU (thermoplastic polyurethane, Shore hardness 58A) containing 0.8 wt% of light-responsive crosslinking agent (4,4'-bis(azido)diphenylmethane), and is processed with a 355 nm ultraviolet laser to form a spiral groove (depth 0.1 mm ± 0.005 mm) and pre-irradiated with 365 nm ultraviolet light for 12 s. The wire bundle is a nickel-plated copper-titanium alloy wire (single wire diameter 0.06 mm) twisted in 130 strands (twist pitch 7 mm, constant temperature embedding at 45°C, tension deviation ≤3%).

[0042] The insulation layer: inner layer (100 parts of crosslinked polyethylene + 8 parts of amino-modified light-responsive graphene quantum dots + 3 parts of DOS), middle layer (100 parts of crosslinked polyethylene + 5 parts of quantum dots + 3 parts of DOS), and outer layer (100 parts of crosslinked polyethylene + 2.5 parts of quantum dots + 3 parts of DOS), thickness ratio 1:1.2:1, total thickness 1.0 mm; three-channel co-extrusion (inner layer 175°C, middle layer 165°C, outer layer 155°C), 20-25°C cold water shaping, three-stage ultraviolet light curing (35 mW / cm²×6 s→90 mW / cm²×11 s→130 mW / cm²×4 s), 90°C hot air drying for 1.5 h.

[0043] The buffer layer: 100 parts of methyl vinyl silicone rubber + 7.5 wt% of barium titanate on the side of the insulation layer and 5.5 wt% of barium titanate on the side of the shielding layer, thickness 0.4 mm; the insulation layer interface is treated with Ar / O2 plasma (volume ratio 3:1, 70 W, 12 s), extruded and coated at 135°C, and the pulling speed is 5 m / min.

[0044] The shielding layer: tin-plated copper wire (single wire diameter 0.09 mm), biaxial servo synchronous weaving (weaving density 96%, synchronization error 0.08%).

[0045] The protective layer: 100 parts of shape memory polyurethane + 18 parts of composite microspheres (50-100 nm, hydroxylated graphene quantum dots account for 18 wt%) + 0.8 parts of light stabilizer 770; the composite microspheres are axially oriented under the assistance of a 0.15 T magnetic field (orientation degree ≥98%), mixed with supercritical CO2 (45°C, 18 MPa), and then extruded and coated at 185°C.

[0046] Post-processing: 365 nm ultraviolet light (90 mW / cm²×12 s)→405 nm ultraviolet light (110 mW / cm²×12 s) to activate the functional components.

[0047] Example 2 differs from Example 1 only in that; ① the elastic core matrix is replaced by SBS (styrene-butadiene-styrene block copolymer, butadiene segment content 35%, processing temperature 180°C); ② the protective layer composite microspheres are added to 22 parts, and the magnetic field strength is increased to 0.2T (orientation degree ≥99%); ③ the total thickness of the insulation layer is 1.2mm, the third stage of the three-stage photocuring light intensity is 150mW / cm²×5s. The rest of the raw materials, process parameters are consistent with Example 1.

[0048] Example 3 differs from Example 1 only in that; ① the total thickness of the insulation layer is 0.8mm, the thickness ratio is kept 1:1.2:1; ② the buffer layer barium titanate gradient is adjusted to 8wt% on the insulation layer side and 6wt% on the shielding layer side, with a thickness of 0.3mm; ③ the protective layer composite microspheres are reduced to 15 parts, and the magnetic field strength is reduced to 0.1T (orientation degree ≥98%). The rest of the raw materials, process parameters are consistent with Example 1.

[0049] Comparative Example 1 differs from Example 1 only in that: the elastic core is not added with 4,4'-bis(azido)diphenylmethane (only TPU + antioxidant 1010), there is no 365nm ultraviolet light pre-irradiation step, and the spiral groove is directly embedded with metal wire after processing. The rest of the raw materials, process parameters are consistent with Example 1.

[0050] Comparative Example 2 differs from Example 1 only in that; ① the inner / middle / outer layers of the insulation layer are all "crosslinked polyethylene 100 parts + amino modified quantum dots 5 parts + DOS 3 parts" (no gradient); ② the photocuring is changed to a single condition (100mW / cm²×20s), without segment control; ③ the three-stage temperature control of the co-extruder is unified to 165°C. The rest of the raw materials, process parameters are consistent with Example 1.

[0051] Comparative Example 3 differs from Example 1 only in that; ① the surface of the insulation layer is not treated by Ar / O2 plasma; ② the buffer layer barium titanate is uniformly added to 6.5wt% (no gradient distribution), with an extrusion temperature of 140°C. The rest of the raw materials, process parameters are consistent with Example 1.

[0052] Comparative Example 4 differs from Example 1 only in that; ① the protective layer composite microspheres are not treated by 0.1-0.2T magnetic field (randomly dispersed); ② no light stabilizer 770 is added; ③ the supercritical CO2 mixing time is shortened to 30min. The rest of the raw materials, process parameters are consistent with Example 1.

[0053] Comparative Example 5 differs from Example 1 only in that: ① the conductor is pure copper wire (single wire diameter 0.08 mm) stranded (no elastic core, no spiral groove, stranded pitch 10 mm); ② the insulating layer is ordinary cross-linked polyethylene (no quantum dots, no DOS); ③ the buffer layer is ordinary nitrile rubber (no barium titanate); ④ the protective layer is ordinary TPE (no shape memory function, no composite microspheres). The rest of the process parameters are simplified as industry conventional processes (such as single-channel extrusion, natural cooling).

[0054] Performance Comparison Table

[0055]

[0056] Bending life: Example (17.8-19.5 million times) because of the use of "elastic core light response crosslinking + insulating layer quantum dot gradient + buffer layer barium titanate gradient + protective layer composite microsphere magnetic field orientation", the bending stress is dispersed; Comparative Example 1 lacks elastic core light response crosslinking agent (10.5 million times), and Comparative Example 5 is a traditional structure (5.1 million times), and the stress concentration causes the life to drop sharply.

[0057] Insulating layer performance: Example (breakdown field strength 35.2-37.5 kV / mm, tear strength 40.5-43.8 MPa) "quantum dot gradient + segmented photocuring", strong crosslinking voltage resistance and tear resistance in the inner layer; Comparative Example 2 has no gradient + single photocuring (29.7 kV / mm, 33.2 MPa), and Comparative Example 5 has no quantum dots (20.3 kV / mm, 21.7 MPa), and the performance is not up to standard.

[0058] Buffer layer peeling strength: Example (3.0-3.3 N / mm) uses Ar / O2 plasma pretreatment to strengthen the interface; Comparative Example 3 has no pretreatment (1.6 N / mm), and the layers are easily peeled apart.

[0059] Protective layer self-repair: Example (92.1-94.8%) relies on core-shell composite microspheres + magnetic field orientation; Comparative Example 4 has no magnetic field + no light stabilizer (75.3%), and the repair efficiency is low.

[0060] The above is only an embodiment of the present application, and relates to circuits and electronic components and modules, which are all prior art. Those skilled in the art can implement the present application without further description. The present application does not involve improvement of software and methods. Commonly known specific structures and characteristics in the scheme are not described in detail herein. Those skilled in the art know all common technical knowledge in the technical field of the present application before the filing date or the priority date, can know all prior art in the field, and have the ability to apply conventional experimental means before the date. Those skilled in the art can perfect and implement the present scheme based on their own ability under the guidance of the present application. Some typical known structures or known methods should not be an obstacle for those skilled in the art to implement the present application. It should be pointed out that, for those skilled in the art, a number of modifications and improvements can be made without departing from the structure of the present application. These should also be considered as the protection scope of the present application, and these will not affect the implementation effect and practicality of the present application.

Claims

1. A bending-resistant flexible cable comprising, from inside to outside, a conductor, an insulation layer, a buffer layer, a shielding layer and a protective layer, characterized in that: The conductor comprises an elastic core and a wire bundle twisted on the periphery of the elastic core; The inner layer of the insulation layer comprises the following components by weight: 100 parts of cross-linked polyethylene, 6-10 parts of amino-modified light-responsive graphene quantum dots, and 2-4 parts of plasticizer DOS; The middle layer of the insulation layer comprises the following components by weight: 100 parts of cross-linked polyethylene, 4-6 parts of amino-modified light-responsive graphene quantum dots, and 2-4 parts of plasticizer DOS; The outer layer of the insulation layer comprises the following components by weight: 100 parts of cross-linked polyethylene, 2-3 parts of amino-modified light-responsive graphene quantum dots, and 2-4 parts of plasticizer DOS; The protective layer comprises the following components by weight: 100 parts of shape memory polyurethane, 15-22 parts of composite microspheres, and 0.5-1.0 parts of light stabilizer, wherein the composite microspheres have a core-shell structure, the core is a mixture of hydroxylated graphene quantum dots and dithiodipropionic acid dihydrazide, and the shell is melamine formaldehyde resin.

2. A kink-resistant flexible electrical cable as claimed in claim 1, characterized in that: The buffer layer is a silicone rubber-barium titanate composite system with a thickness of 0.3-0.5 mm, and the interface between the buffer layer and the insulation layer is pretreated by plasma.

3. A kink-resistant flexible electrical cable as claimed in claim 2, characterized in that; The buffer layer uses methyl vinyl silicone rubber as a matrix and uniformly disperses barium titanate particles as a functional filler in the matrix, the mass fraction of barium titanate on the side of the buffer layer close to the insulation layer is 7-8 wt%, the mass fraction of barium titanate on the side of the buffer layer close to the shielding layer is 5-6 wt%, and the dielectric constant of the buffer layer decreases from the side of the insulation layer to the side of the shielding layer, forming a micro-graded distribution of the dielectric constant along the radial direction.

4. A kink-resistant flexible electrical cable as defined in claim 1, wherein: The shielding layer is a braided layer of tin-plated copper wires.

5. A kink-resistant flexible electrical cable according to claim 1, wherein: The elastic core is a thermoplastic elastomer containing 0.5-1.5 wt% of a light-responsive cross-linking agent.

6. A kink-resistant flexible electrical cable according to claim 5, wherein: The wire bundle is a nickel-plated copper-titanium alloy wire with a single wire diameter of 0.04-0.07 mm and a twisting pitch of 6-8 times the diameter of the wire bundle.

7. A kink-resistant flexible electrical cable according to claim 1, wherein: The thickness ratio of the inner layer, the middle layer, and the outer layer of the insulation layer is 1:1.2:1, and the total thickness is 0.8-1.2 mm.

8. A kink-resistant flexible electrical cable according to claim 7, wherein: The preparation method of the insulation layer comprises the following steps: Prepare the slurry of the inner layer, the middle layer, and the outer layer of the insulation layer, and perform ultrasonic dispersion for 30-40 min and then degassing; Use a three-channel co-extrusion machine to segmentally control the temperature of the inner layer at 170-180°C, the middle layer at 160-170°C, and the outer layer at 150-160°C, synchronously coat the three layers of slurry on the conductor, and then perform cold water shaping at 20-25°C; After cold water shaping, perform three-stage ultraviolet light curing by sequentially irradiating at 30-40 mW / cm² for 5-8 seconds, 80-100 mW / cm² for 10-12 seconds, and 120-150 mW / cm² for 3-5 seconds; and finally, perform hot air drying at 85-95°C for 1-2 hours.

9. A kink-resistant flexible electrical cable according to claim 1, wherein: The composite microspheres are axially oriented by magnetic field assistance, and the magnetic field strength is 0.1-0.2 T.

10. A method for the production of a kink-resistant flexible electrical cable for the production of a kink-resistant flexible electrical cable according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: S1. Conductor preparation: S11. Add the thermoplastic elastomer, the light-responsive cross-linking agent, and the antioxidant 1010 into a double-screw extruder in proportion, melt blend at 180-200°C, and extrude into an elastic core rough blank with a diameter of 0.4-0.6 mm; S12. When the elastic core rough blank is cooled to 80-90℃, a helical groove is processed by using ultraviolet laser, and then the helical groove is pre-irradiated by 365nm ultraviolet light for 10-15s; S13. The metal wire bundle is embedded and twisted in the helical groove in a constant temperature environment of 40-50℃ to obtain a conductor; S2. Insulating layer preparation: S21. The inner, middle and outer layer slurries of the insulating layer are respectively prepared, and after ultrasonic dispersion for 30-40min, they are degassed; the three-channel gradient co-extrusion machine is used to coat the conductor periphery, and after extrusion, the 20-25℃ cold water is used for shaping, and the co-extrusion machine is controlled in three sections, wherein the inner layer temperature is controlled at 170-180℃, the middle layer temperature is controlled at 160-170℃, and the outer layer temperature is controlled at 150-160℃; S22. Adopt three-stage ultraviolet light curing: 30-40 mW / cm2 irradiation for 5-8 seconds, 80-100 mW / cm2 irradiation for 10-12 seconds, 120-150 mW / cm2 irradiation for 3-5 seconds, and then drying in an 85-95 °C oven for 1-2 h to obtain an insulated wire core. 2 30-40 mW / cm2 irradiation for 5-8 seconds, 80-100 mW / cm2 irradiation for 10-12 seconds, 120-150 mW / cm2 irradiation for 3-5 seconds, and then drying in an 85-95 °C oven for 1-2 h to obtain an insulated wire core. S3. Buffer layer coating: S31. The surface of the insulating wire core is treated by Ar / O2 plasma; S32. The silicone rubber-barium titanate composite slurry is coated on the periphery of the treated insulating wire core by using an extruder, the extrusion temperature is 130-140℃, the pulling speed is 4-6m / min, and the cooling shaping is performed; S4. Shielding layer weaving: S41. The tinned copper wire is woven by using a double-shaft servo synchronous system to obtain a shielding wire core; S5. Protective layer preparation: S51. The shape memory polyurethane, composite microspheres and light stabilizer are added into a supercritical CO2 reaction kettle, and ultrasonic assisted mixing is performed for 40-50min; S52. The mixed system is coated on the periphery of the shielding wire core by using an extruder, a permanent magnet array is arranged at the outlet section of the extrusion die, the extrusion temperature is 175-190℃, and the cooling shaping is performed; S6. Post-processing: S61. First, the conductor elastic core is activated by 365nm ultraviolet light for 10-15s to activate the light response crosslinking agent; S62. Then, the light response components of the insulating layer and the protective layer are activated by 405nm ultraviolet light for 10-15s, and the preparation is completed.

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