Low temperature resistant flexible cable and method for manufacturing the same

Abstract

The application relates to the technical field of cables, and particularly discloses a low-temperature-resistant flexible cable and a preparation method thereof. The low-temperature-resistant flexible cable comprises a conductor, an insulation layer, a cabling unit, a shielding layer and an outer sheath which are sequentially arranged, and the raw material of the outer sheath comprises the following components in parts by weight: 100 parts of PVC resin, 12-25 parts of powder nitrile rubber, 5-15 parts of polyether TPU, 6-18 parts of maleic anhydride grafted POE, 8-18 parts of dioctyl sebacate, 6-15 parts of dioctyl adipate, 5-15 parts of polyester plasticizer, 3-8 parts of epoxy soybean oil, 4-12 parts of silane modified nano calcium carbonate, 3-6 parts of calcium-zinc composite stabilizer, 0.2-0.8 parts of antioxidant, 0.8-3 parts of matt black masterbatch, 0.5-2 parts of lubricant and 0.5-2 parts of silicone masterbatch. The cable in the application still has good flexibility in a low-temperature environment.

Description

Technical Field

[0001] This application relates to the technical field of cables, and in particular to a low-temperature resistant flexible cable and its preparation method. Background Technology

[0002] Traditional PVC insulated and sheathed cables can meet general electrical transmission requirements at room temperature, but they have significant drawbacks at low temperatures: First, the movement of PVC molecular chain segments is restricted, resulting in a high glass transition temperature and brittleness at low temperatures, leading to cracking and a bending life of less than 1 million cycles. Second, conventional conductors use single-diameter stranded hard copper wires, which can cause stress concentration during low-temperature bending, leading to single-wire breakage, resulting in circuit breaks, poor contact, or abnormal signal transmission. Third, ordinary shielding structures have insufficient electromagnetic interference resistance, and the shielding layer has poor adhesion to the sheath, making it prone to shielding layer detachment and signal transmission distortion during low-temperature dragging. Existing improvement solutions often use thermoplastic elastomers to replace PVC, but these generally suffer from high costs, poor processing fluidity, and poor compatibility with the conductor and shielding layer interfaces, making it difficult to simultaneously meet the requirements of low-temperature resistance, flexibility, and industrial mass production. Summary of the Invention

[0003] In order to obtain a cable that combines low-temperature resistance and flexibility, this application provides a low-temperature resistant flexible cable and a method for its preparation.

[0004] Firstly, this application provides a low-temperature resistant flexible cable, which adopts the following technical solution: A low-temperature resistant flexible cable includes a conductor, an insulation layer, a cabling unit, a shielding layer, and an outer sheath arranged sequentially. The outer sheath is made of the following components in parts by weight: 100 parts PVC resin, 12-25 parts powdered nitrile rubber, 5-15 parts polyether-type TPU, 6-18 parts maleic anhydride-grafted POE, 8-18 parts dioctyl sebacate, 6-15 parts dioctyl adipate, 5-15 parts polyester plasticizer, 3-8 parts epoxidized soybean oil, 4-12 parts silane-modified nano-calcium carbonate, 3-6 parts calcium-zinc composite stabilizer, 0.2-0.8 parts antioxidant, 0.8-3 parts matte black masterbatch, 0.5-2 parts lubricant, and 0.5-2 parts silicone masterbatch.

[0005] By adopting the above technical solution, PVC resin serves as the continuous phase, and powdered nitrile rubber, polyether-type TPU, and maleic anhydride-grafted POE together form a multiphase elastic toughening system. Among them, powdered nitrile rubber improves the problem of PVC hardening at low temperatures, polyether-type TPU enhances low-temperature resilience, abrasion resistance, and tear resistance, and maleic anhydride-grafted POE provides a flexible elastic phase at low temperatures, thus enabling the outer sheath to maintain good flexibility in low-temperature environments. The polar grafting groups in maleic anhydride-grafted POE can improve the interfacial bonding between POE and PVC, powdered nitrile rubber, and TPU, reduce the problem of poor dispersion of ordinary POE in the PVC system, and enable the flexible phase to be uniformly distributed in the PVC matrix. Dioctyl sebacate, dioctyl adipate, and polyester plasticizers together constitute a cold-resistant plasticizing system. Dioctyl sebacate and dioctyl adipate can reduce the low-temperature hardening tendency of the PVC matrix, while polyester plasticizers can reduce the migration risk of small-molecule cold-resistant plasticizers, allowing the outer sheath to maintain flexibility after long-term use and heat aging. Silane-modified nano-calcium carbonate can be uniformly dispersed in the composite elastic matrix to form microscale stress dispersion points, avoiding ordinary inorganic fillers from becoming crack sources at low temperatures, thereby improving the sheath's low-temperature impact, low-temperature winding, and repeated bending performance. The combined action of calcium-zinc composite stabilizer, epoxidized soybean oil, antioxidant, lubricant, and silicone masterbatch can improve the processing thermal stability of PVC sheath material, reduce the risk of decomposition, scorching, and die accumulation during extrusion, and improve the surface smoothness, abrasion resistance, and drag performance of the sheath.

[0006] In one specific implementation, the method for preparing the silane-modified nano-calcium carbonate includes the following steps: Take nano-calcium carbonate with a particle size of 40-100 nm and dry it at 100-120℃ for 2.5-3.5 h; separately take anhydrous ethanol, deionized water and glacial acetic acid, mix them, adjust the pH to 4.5, then add silane coupling agent and PEG-400, stir and hydrolyze at 28-32℃ to obtain silane hydrolysate; The dried nano-calcium carbonate was added to a high-speed mixer, the powder temperature was controlled at 85-95℃, and the mixture was stirred at a speed of 1200 r / min. The silane hydrolysate was atomized and sprayed into the high-speed mixer. After the spraying was completed, the mixing and stirring continued. Then the temperature was raised to 105℃ and the stirring continued. Subsequently, the resulting powder was vacuum dried, and after air jet pulverization and sieving, silane-modified nano-calcium carbonate was obtained.

[0007] By adopting the above technical solutions and methods, silane-modified nano-calcium carbonate with uniform surface coating, low moisture content, minimal agglomeration, and good compatibility with the organic sheath system can be obtained, thereby improving the low-temperature crack resistance, wear resistance, and surface quality of the outer sheath.

[0008] In one specific implementation scheme, the weight ratio of the nano-calcium carbonate, silane coupling agent, and PEG-400 is 100:(2.0-2.4):(0.3-0.4).

[0009] By adopting the above technical solution and optimizing the ratio of silane coupling agent and PEG-400, the surface modification efficiency and dispersion stability of nano-calcium carbonate are improved, thereby further enhancing the low-temperature crack resistance and mechanical property stability of the outer sheath.

[0010] In one specific implementation, the antioxidant comprises a mixture of antioxidant 1010 and antioxidant 168.

[0011] By adopting the above technical solution, the combination of hindered phenolic primary antioxidant and phosphite auxiliary antioxidant can improve the processing stability, thermal aging stability and low-temperature flexibility retention of the outer sheath material.

[0012] In one specific implementation, the lubricant comprises a mixture of oxidized polyethylene wax and PE wax.

[0013] By adopting the above technical solutions, the extrusion processability, filler dispersibility, surface quality, and low-temperature crack resistance of the outer sheath material are improved through the synergistic effect of internal and external lubrication and dispersion lubrication.

[0014] Secondly, this application provides a method for preparing a low-temperature resistant flexible cable, which adopts the following technical solution: A method for preparing a low-temperature resistant flexible cable includes the following steps: Preparation of outer sheath material: PVC resin, calcium-zinc composite stabilizer, epoxidized soybean oil, and antioxidant are added to a high-speed mixer and mixed at 300-500 r / min for 2-3 min; the speed is increased to 900-1200 r / min, and when the material temperature rises to 55-65℃, dioctyl sebacate, dioctyl adipate, and polyester plasticizer are added sequentially, and mixing continues to 95℃; then silane-modified nano calcium carbonate, powdered nitrile rubber, matte black masterbatch, and lubricant are added, and mixing continues to 105-110℃ before discharge and cooling. When the material temperature drops below 45℃, polyether-type TPU, maleic anhydride-grafted POE, and silicone masterbatch are added and mixed for 5-8 min to obtain a premix; the premix is ​​added to a twin-screw extruder for melt blending and granulation, and after extrusion and pelletizing, the outer sheath material is obtained; Conductor stranding: 26 fine copper wires with a diameter of 0.1 mm and 2 copper foil wires with a diameter of 0.23 mm are stranded to the left, with the stranding pitch controlled at 13 mm. The outer diameter of the conductor after stranding is 0.7 mm. Insulation extrusion: A colored PVC insulation layer is extruded over the conductor. The insulation extrusion process is used to produce yellow, blue, green and red insulated wire cores respectively. Cable forming and wrapping: The yellow, blue, green and red insulated wire cores are twisted into a cable in left-hand order, and cotton rope is added to the center for filling. The cable pitch is controlled at 20-23mm. Single-sided aluminum foil is wrapped around the outer layer with the metal side of the aluminum foil facing outward and the overlap rate is 20%. The outer diameter after wrapping is controlled at 3.5-3.7mm, and the cable unit is obtained by molding. Shielding layer assembly: A composite guide wire is set on the outside of the aluminum foil of the cabling unit, which is formed by combining 30 fine copper wires with a diameter of 0.1 mm and 3 copper foil wires with a diameter of 0.23 mm. The composite guide wire is in contact with the metal surface of the aluminum foil. The aluminum foil and the composite guide wire together form a shielding layer. The outer diameter after shielding is controlled to be 3.7-3.9 mm. Outer sheath extrusion: The outer sheath material is dried and extruded onto the outside of the shielding layer using a tube extrusion process to form the outer sheath; Post-processing: After the outer sheath is extruded, it is cooled and shaped in sections of cooling water tanks at 35-45℃ and 20-30℃, and then printed for inspection to obtain a low-temperature resistant flexible cable.

[0015] By adopting the above technical solutions and utilizing the synergistic control of the outer sheath material preparation process, cable structure forming process, and cooling post-treatment process, the cable can possess low-temperature flexibility, drag resistance, bending fatigue resistance, shielding stability, and industrial mass production stability.

[0016] In one specific implementation, the thickness of the insulating layer in the insulating extrusion step is 0.3-0.5 mm.

[0017] In one specific implementation, during the outer sheath extrusion step, the extrusion temperature is set sequentially to 138℃, 148℃, 158℃, 163℃, 165℃, 165℃ and 162℃, and the traction speed is 10-14m / min.

[0018] In one specific implementation, during the outer sheath extrusion step, the thickness of the outer sheath is 0.8-1.2 mm.

[0019] By adopting the above technical solution and utilizing a specific low-temperature slow extrusion process, the outer sheath material is fully plasticized without thermal decomposition. The sheath thickness of 0.8-1.2mm can effectively protect the internal shielding layer, cabling unit and insulated core, improve wear resistance, drag resistance and impact resistance, and improve the appearance quality, dimensional stability and low-temperature crack resistance of the sheath.

[0020] In summary, this application includes at least one of the following beneficial technical effects: In this application, a multiphase elastic toughening system is constructed by introducing powdered nitrile rubber, polyether-type TPU, and maleic anhydride-grafted POE into a PVC matrix; a cold-resistant and migration-resistant plasticizing system is constructed by using dioctyl sebacate, dioctyl adipate, and polyester plasticizer; a low-temperature stress dispersion structure is formed by modifying nano-calcium carbonate with silane, and calcium-zinc composite stabilizer, compound antioxidant, compound lubricant, and silicone masterbatch are used to improve the processing stability, surface quality, and drag resistance of the outer sheath. Therefore, the resulting cable can combine low-temperature resistance and flexibility. This application obtains silane-modified nano-calcium carbonate with uniform surface coating, low moisture content, less agglomeration, and good compatibility with organic sheathing systems, thereby improving the low-temperature crack resistance, wear resistance, and surface quality of the outer sheath. The preparation method in this application employs a composite copper foil conductor, a small-pitch cable structure, an aluminum foil and composite current-conducting wire shielding structure, and an extrusion sheath forming process, which enables the cable to maintain good flexibility, resistance to bending fatigue, shielding stability, and wear and crack resistance even in low-temperature environments. Detailed Implementation

[0021] The present application will be further described in detail below with reference to the embodiments.

[0022] All raw materials used in the examples are commercially available. The PVC resin is SG-3; the polyether TPU is Wanthane® WHT-8185; the maleic anhydride-grafted POE is Fine-Blend® CMG5805-L; the polyester plasticizer is an adipic acid-based polyester plasticizer; and the silicone masterbatch is WACKER GENIOPLAST® Pellet S. Preparation Example

[0023] Preparation Example 1 Preparation Example 1 provides a method for preparing silane-modified nano-calcium carbonate, comprising the following steps: Nano-sized calcium carbonate with a particle size of 40-100 nm was dried at 110℃ for 3 h. Separately, anhydrous ethanol, deionized water, and glacial acetic acid were mixed and the pH adjusted to 4.5. A silane coupling agent and PEG-400 were then added, and the mixture was stirred and hydrolyzed at 30℃ for 40 min to obtain a silane hydrolysate. The weight ratio of anhydrous ethanol, deionized water, glacial acetic acid, silane coupling agent, and PEG-400 was 6:0.8:0.06:2.0:0.3; the silane coupling agent was KH-570; and the weight ratio of nano-sized calcium carbonate, silane coupling agent, and PEG-400 was 100:2.0:0.3. The dried nano-calcium carbonate was added to a high-speed mixer, the powder temperature was controlled at 90℃, and the mixture was stirred at a speed of 1200 r / min. The silane hydrolysate was atomized and sprayed into the high-speed mixer. After the spraying was completed, the mixture was stirred for 25 min. Then the temperature was raised to 105℃ and stirred for 20 min. The resulting powder was then vacuum dried at 100℃ for 2.5 h. After air jet pulverization and sieving, silane-modified nano-calcium carbonate was obtained.

[0024] Preparation Example 2 The difference between Preparation Example 2 and Preparation Example 1 is that nano-calcium carbonate with a particle size of 40-100 nm was dried at 110 °C for 3 h; separately, anhydrous ethanol, deionized water, and glacial acetic acid were mixed, the pH was adjusted to 4.5, and then silane coupling agent and PEG-400 were added. The mixture was stirred and hydrolyzed at 30 °C for 40 min to obtain a silane hydrolysate; wherein the weight ratio of anhydrous ethanol, deionized water, glacial acetic acid, silane coupling agent, and PEG-400 was 6:0.8:0.06:2.2:0.35; the silane coupling agent was KH-570; and the weight ratio of nano-calcium carbonate, silane coupling agent, and PEG-400 was 100:2.2:0.35; the remaining steps were the same as in Preparation Example 1.

[0025] Preparation Example 3 The difference between Preparation Example 3 and Preparation Example 1 is that nano-calcium carbonate with a particle size of 40-100 nm was dried at 110 °C for 3 h; separately, anhydrous ethanol, deionized water, and glacial acetic acid were mixed, the pH was adjusted to 4.5, and then silane coupling agent and PEG-400 were added. The mixture was stirred and hydrolyzed at 30 °C for 40 min to obtain a silane hydrolysate; the weight ratio of anhydrous ethanol, deionized water, glacial acetic acid, silane coupling agent, and PEG-400 was 6:0.8:0.06:2.4:0.4; the silane coupling agent was KH-570; and the weight ratio of nano-calcium carbonate, silane coupling agent, and PEG-400 was 100:2.4:0.4; the remaining steps were the same as in Preparation Example 1. Example

[0026] Example 1 Example 1 provides a method for preparing a low-temperature resistant flexible cable, comprising the following steps: Preparation of outer sheath material: 100 kg of PVC resin, 3 kg of calcium-zinc composite stabilizer, 3 kg of epoxidized soybean oil, and 0.2 kg of antioxidant were added to a high-speed mixer and mixed at 400 r / min for 3 min. The speed was increased to 1100 r / min, and when the material temperature reached 60℃, 8 kg of dioctyl sebacate, 6 kg of dioctyl adipate, and 5 kg of polyester plasticizer were added sequentially, and mixing continued until 95℃ was reached. Then, 4 kg of silane-modified nano-calcium carbonate from Preparation Example 1, 12 kg of powdered nitrile rubber, 0.8 kg of matte black masterbatch, and 0.5 kg of lubricant were added, and mixing continued until 108℃ was reached. The mixture was then discharged and cooled. When the material temperature dropped below 45℃, 5 kg of polyether-type TP was added. U, 6 kg of maleic anhydride-grafted POE, and 0.5 kg of silicone masterbatch were mixed for 7 min to obtain a premix. The premix was then added to a twin-screw extruder for melt blending and granulation. The twin-screw temperatures were set sequentially to 130℃, 140℃, 150℃, 158℃, 163℃, 163℃, and 158℃, with a die temperature of 160℃, a screw speed of 200 r / min, and a vacuum of -0.08 MPa. After extrusion and pelletizing, an outer sheath material was obtained. The antioxidant was a mixture of antioxidant 1010 and antioxidant 168 in a weight ratio of 2:1. The lubricant was a mixture of oxidized polyethylene wax and PE wax in a weight ratio of 4:1. Conductor stranding: 26 fine copper wires with a diameter of 0.1 mm and 2 copper foil wires with a diameter of 0.23 mm are stranded to the left, with the stranding pitch controlled at 13 mm. The outer diameter of the conductor after stranding is 0.7 mm. Insulation extrusion: A colored PVC insulation layer is extruded over the conductor. The insulation extrusion adopts an extrusion process with a core diameter of 0.8mm, a die sleeve diameter of 1.5mm, an extrusion temperature of 158℃, an insulation layer thickness of 0.4mm, and an insulation outer diameter of 1.47mm, producing yellow, blue, green, and red insulated wire cores respectively. Cable winding: The yellow, blue, green and red insulated wire cores are twisted into a cable in left-hand order, and cotton rope is added to the center for filling. The cable pitch is controlled at 23mm. 0.028mm×12mm aluminum foil is wrapped around the outside of the cable unit, with the metal side of the aluminum foil facing outward and the overlap rate at 20%. The outer diameter after wrapping is controlled at 3.6mm, and it is shaped by a 3.6mm sizing mold to obtain the cable unit. Shielding layer assembly: A composite current-guiding wire is set on the outside of the aluminum foil of the cabling unit, which is formed by combining 30 fine copper wires with a diameter of 0.1mm and 3 copper foil wires with a diameter of 0.23mm. The composite current-guiding wire is in contact with the metal surface of the aluminum foil. The aluminum foil and the composite current-guiding wire together form a shielding layer. The outer diameter is controlled to be 3.8mm after shielding. Outer sheath extrusion: After drying the outer sheath material at 75℃ for 2 hours, it is extruded onto the outside of the shielding layer using a tube extrusion process. The die core is 4.5mm and the die sleeve is 8.2mm. The extrusion temperatures are set sequentially to 138℃, 148℃, 158℃, 163℃, 165℃, 165℃ and 162℃, and the traction speed is 12m / min, forming an outer sheath with a thickness of 1.0mm and an outer diameter of 5.8mm. Post-processing: After the outer sheath is extruded, it is cooled and shaped in sections of cooling water baths at 40℃ and 25℃, and then printed for inspection to obtain a low-temperature resistant flexible cable.

[0027] Example 2 The difference between Example 2 and Example 1 lies in the preparation of the outer sheath material: 100 kg of PVC resin, 4.5 kg of calcium-zinc composite stabilizer, 5.5 kg of epoxidized soybean oil, and 0.5 kg of antioxidant were added to a high-speed mixer and mixed at 400 r / min for 3 min; the speed was increased to 1100 r / min, and when the material temperature reached 60°C, 13 kg of dioctyl sebacate, 10.5 kg of dioctyl adipate, and 10 kg of polyester plasticizer were added sequentially, and mixing continued until 95°C; then 8 kg of silane-modified nano-calcium carbonate from Example 1, 18 kg of powdered nitrile rubber, 1.9 kg of matte black masterbatch, and 1.25 kg of lubricant were added, and mixing continued until 10... After cooling the material at 8°C, when the material temperature drops below 45°C, add 10kg of polyether-type TPU, 12kg of maleic anhydride-grafted POE, and 1.25kg of silicone masterbatch, and mix for 7 minutes to obtain a premix. Add the premix to a twin-screw extruder for melt blending and granulation. The twin-screw temperatures are set sequentially to 130°C, 140°C, 150°C, 158°C, 163°C, 163°C, and 158°C, with a die head temperature of 160°C, a screw speed of 200 r / min, and a vacuum degree of -0.08 MPa. After extrusion and pelletizing, the outer sheath material is obtained. The remaining steps are consistent with those in Example 1.

[0028] Example 3 The difference between Example 3 and Example 1 lies in the preparation of the outer sheath material: 100 kg of PVC resin, 6 kg of calcium-zinc composite stabilizer, 8 kg of epoxidized soybean oil, and 0.8 kg of antioxidant were added to a high-speed mixer and mixed at 400 r / min for 3 min; the speed was increased to 1100 r / min, and when the material temperature reached 60°C, 18 kg of dioctyl sebacate, 15 kg of dioctyl adipate, and 15 kg of polyester plasticizer were added sequentially, and mixing continued until 95°C; then 12 kg of silane-modified nano-calcium carbonate from Example 1, 25 kg of powdered nitrile rubber, 3 kg of matte black masterbatch, and 2 kg of lubricant were added, and mixing continued until 108°C. After cooling the discharged material, when the temperature drops below 45°C, add 15kg of polyether-type TPU, 18kg of maleic anhydride-grafted POE, and 2kg of silicone masterbatch, and mix for 7 minutes to obtain a premix. Add the premix to a twin-screw extruder for melt blending and granulation. The twin-screw temperatures are set sequentially to 130°C, 140°C, 150°C, 158°C, 163°C, 163°C, and 158°C, with a die head temperature of 160°C, a screw speed of 200 r / min, and a vacuum of -0.08 MPa. After extrusion and pelletizing, the outer sheath material is obtained. The remaining steps are consistent with those in Example 1.

[0029] Example 4 The difference between Example 4 and Example 2 lies in the preparation of the outer sheath material: 100 kg of PVC resin, 4.5 kg of calcium-zinc composite stabilizer, 5.5 kg of epoxidized soybean oil, and 0.5 kg of antioxidant were added to a high-speed mixer and mixed at 400 r / min for 3 min; the speed was increased to 1100 r / min, and when the material temperature reached 60°C, 13 kg of dioctyl sebacate, 10.5 kg of dioctyl adipate, and 10 kg of polyester plasticizer were added sequentially, and mixing continued until 95°C; then 8 kg of silane-modified nano-calcium carbonate, 18 kg of powdered nitrile rubber, 1.9 kg of matte black masterbatch, and 1.25 kg of lubricant from Example 2 were added, and mixing continued until 10... After cooling the material at 8°C, when the material temperature drops below 45°C, add 10kg of polyether-type TPU, 12kg of maleic anhydride-grafted POE, and 1.25kg of silicone masterbatch, and mix for 7 minutes to obtain a premix. Add the premix to a twin-screw extruder for melt blending and granulation. The twin-screw temperatures are set sequentially to 130°C, 140°C, 150°C, 158°C, 163°C, 163°C, and 158°C, with a die head temperature of 160°C, a screw speed of 200 r / min, and a vacuum degree of -0.08 MPa. After extrusion and pelletizing, the outer sheath material is obtained. The remaining steps are consistent with those in Example 2.

[0030] Example 5 The difference between Example 5 and Example 2 lies in the preparation of the outer sheath material: 100 kg of PVC resin, 4.5 kg of calcium-zinc composite stabilizer, 5.5 kg of epoxidized soybean oil, and 0.5 kg of antioxidant were added to a high-speed mixer and mixed at 400 r / min for 3 min; the speed was increased to 1100 r / min, and when the material temperature reached 60°C, 13 kg of dioctyl sebacate, 10.5 kg of dioctyl adipate, and 10 kg of polyester plasticizer were added sequentially, and mixing continued until 95°C; then 8 kg of silane-modified nano-calcium carbonate from Example 3, 18 kg of powdered nitrile rubber, 1.9 kg of matte black masterbatch, and 1.25 kg of lubricant were added, and mixing continued until 10... After cooling the material at 8°C, when the material temperature drops below 45°C, add 10kg of polyether-type TPU, 12kg of maleic anhydride-grafted POE, and 1.25kg of silicone masterbatch, and mix for 7 minutes to obtain a premix. Add the premix to a twin-screw extruder for melt blending and granulation. The twin-screw temperatures are set sequentially to 130°C, 140°C, 150°C, 158°C, 163°C, 163°C, and 158°C, with a die head temperature of 160°C, a screw speed of 200 r / min, and a vacuum degree of -0.08 MPa. After extrusion and pelletizing, the outer sheath material is obtained. The remaining steps are consistent with those in Example 2.

[0031] Example 6 The difference between Example 6 and Example 4 is that the lubricant is oxidized polyethylene wax; the remaining steps are the same as in Example 4.

[0032] Example 7 The difference between Example 7 and Example 4 is that the lubricant is PE wax; the remaining steps are the same as in Example 4. Comparative Example

[0033] Comparative Example 1 The difference between Comparative Example 1 and Example 1 lies in the preparation of the outer sheath material: 123 kg of PVC resin, 3 kg of calcium-zinc composite stabilizer, 3 kg of epoxidized soybean oil, and 0.2 kg of antioxidant were added to a high-speed mixer and mixed at 400 r / min for 3 min; the speed was increased to 1100 r / min, and when the material temperature reached 60°C, 8 kg of dioctyl sebacate, 6 kg of dioctyl adipate, and 5 kg of polyester plasticizer were added sequentially, and mixing continued until 95°C; then 4 kg of silane-modified nano-calcium carbonate, 0.8 kg of matte black masterbatch, and 0.5 kg of lubricant from Example 1 were added, and mixing continued. After reaching 108°C, the material is discharged and cooled. When the material temperature drops below 45°C, 0.5 kg of silicone masterbatch is added and mixed for 7 minutes to obtain a premix. The premix is ​​then added to a twin-screw extruder for melt blending and granulation. The twin-screw temperatures are set sequentially to 130°C, 140°C, 150°C, 158°C, 163°C, 163°C, and 158°C, with a die head temperature of 160°C, a screw speed of 200 r / min, and a vacuum of -0.08 MPa. After extrusion and pelletizing, the outer sheath material is obtained. The remaining steps are consistent with those in Example 1.

[0034] Comparative Example 2 The difference between Comparative Example 2 and Example 1 lies in the preparation of the outer sheath material: 111 kg of PVC resin, 3 kg of calcium-zinc composite stabilizer, 3 kg of epoxidized soybean oil, and 0.2 kg of antioxidant were added to a high-speed mixer and mixed at 400 r / min for 3 min; the speed was increased to 1100 r / min, and when the material temperature reached 60°C, 8 kg of dioctyl sebacate, 6 kg of dioctyl adipate, and 5 kg of polyester plasticizer were added sequentially, and mixing continued until 95°C; then 4 kg of silane-modified nano-calcium carbonate from Example 1, 12 kg of powdered nitrile rubber, 0.8 kg of matte black masterbatch, and 0.5 kg of lubricant were added. Continue mixing until the temperature reaches 108°C, then discharge and cool. When the material temperature drops below 45°C, add 0.5 kg of silicone masterbatch and mix for 7 minutes to obtain a premix. Add the premix to a twin-screw extruder for melt blending and granulation. The twin-screw temperatures are set sequentially to 130°C, 140°C, 150°C, 158°C, 163°C, 163°C, and 158°C, with a die head temperature of 160°C, a screw speed of 200 r / min, and a vacuum of -0.08 MPa. After extrusion and pelletizing, the outer sheath material is obtained. The remaining steps are consistent with those in Example 1.

[0035] Comparative Example 3 The difference between Comparative Example 3 and Example 1 lies in the preparation of the outer sheath material: 114 kg of PVC resin, 3 kg of calcium-zinc composite stabilizer, 3 kg of epoxidized soybean oil, and 0.2 kg of antioxidant were added to a high-speed mixer and mixed at 400 r / min for 3 min; the speed was increased to 1100 r / min, and when the material temperature reached 60°C, 5 kg of polyester plasticizer was added, and mixing continued until 95°C; then 4 kg of silane-modified nano-calcium carbonate from Example 1, 12 kg of powdered nitrile rubber, 0.8 kg of matte black masterbatch, and 0.5 kg of lubricant were added, and mixing continued until 108°C, after which the material was discharged and cooled. When the temperature drops below 45°C, add 5 kg of polyether-type TPU, 6 kg of maleic anhydride-grafted POE, and 0.5 kg of silicone masterbatch, and mix for 7 min to obtain a premix. Add the premix to a twin-screw extruder for melt blending and granulation. The twin-screw temperatures are set sequentially to 130°C, 140°C, 150°C, 158°C, 163°C, 163°C, and 158°C, with a die head temperature of 160°C, a screw speed of 200 r / min, and a vacuum of -0.08 MPa. After extrusion and pelletizing, the outer sheath material is obtained. The remaining steps are consistent with those in Example 1.

[0036] Comparative Example 4 The difference between Comparative Example 4 and Example 1 lies in the preparation of the outer sheath material: 100 kg of PVC resin, 3 kg of calcium-zinc composite stabilizer, 3 kg of epoxidized soybean oil, and 0.2 kg of antioxidant were added to a high-speed mixer and mixed at 400 r / min for 3 min; the speed was increased to 1100 r / min, and when the material temperature reached 60°C, 8 kg of dioctyl sebacate, 6 kg of dioctyl adipate, and 5 kg of polyester plasticizer were added sequentially, and mixing continued until 95°C; then 4 kg of nano-calcium carbonate, 12 kg of powdered nitrile rubber, 0.8 kg of matte black masterbatch, and 0.5 kg of lubricant were added, and mixing continued until 108°C before discharge and cooling. When the material temperature drops below 45℃, add 5kg of polyether-type TPU, 6kg of maleic anhydride-grafted POE, and 0.5kg of silicone masterbatch, mix for 7 minutes to obtain a premix; add the premix to a twin-screw extruder for melt blending and granulation, with the twin-screw temperatures set sequentially to 130℃, 140℃, 150℃, 158℃, 163℃, 163℃, and 158℃, the die head temperature at 160℃, the screw speed at 200 r / min, and the vacuum degree at -0.08 MPa. After extrusion and pelletizing, the outer sheath material is obtained; the remaining steps are consistent with Example 1. Performance testing experiment

[0037] Low-temperature resistance performance: The low-temperature winding test and low-temperature impact test were conducted according to GB / T 2951.14-2008 "General Test Methods for Insulation and Sheath Materials of Cables and Optical Fibers - Part 14: General Test Methods - Low Temperature Test". Five finished cables with a length of 600mm were used as samples per group. The samples were placed in a low-temperature test chamber and kept at -40℃ for 4 hours. Immediately after removal, a low-temperature winding test was performed, with the winding mandrel diameter being 6 times the cable's outer diameter, for 5 turns. The outer sheath surface was observed for cracks, splitting, or peeling. A separate 300mm finished cable was used as a low-temperature impact sample. Five samples were taken from each group; the samples were placed in a low-temperature test chamber and kept at a constant temperature of -50℃ for 4 hours; immediately after removal, a low-temperature impact test was performed with an impact hammer of 1000g and an impact height of 100mm. After the impact, the outer sheath was observed to see if it cracked; after the impact, the samples were subjected to a 1500V / 5min withstand voltage test, and the breakdown was recorded; the low-temperature resistance performance was expressed by the sheath cracking rate after low-temperature impact. The lower the cracking rate, the better the low-temperature resistance performance of the cable; the sheath cracking rate after low-temperature impact was calculated according to the following formula: Sheath cracking rate after low-temperature impact = number of cracked samples / total number of samples × 100%.

[0038] Bending performance: Referring to the bending test method for flexible cables in GB / T 5023.2-2008, a finished cable with a length of 2.5m was used as the sample, and 3 samples were taken for each group. The samples were installed in a low-temperature dynamic bending test device, the test temperature was -40℃, the bending radius was 6 times the outer diameter of the cable, and the bending frequency was 30 times / min. During the test, a continuous continuity detection signal was applied to the conductor. The number of bends when the cable under any of the following conditions occurred was taken as the dynamic bending life: instantaneous or continuous open circuit of the conductor; short circuit between any two cores; visible through cracks in the outer sheath; obvious loosening, breakage or separation of the shielding layer from the aluminum foil; failure of the 1500V / 5min withstand voltage test after bending. When the sample reached the set number of bends and the above failure conditions did not occur, its dynamic bending life was recorded, and the average value of 3 samples in each group was taken as the test result.

[0039] Signal transmission stability: The test was conducted according to the transfer impedance test method in IEC 62153-4-3 and the test approach for conducted interference immunity induced by radio frequency field in GB / T17626.6-2017. Three finished cables of 10m length were used as samples. The shielding attenuation value of the cable was first tested at room temperature. Then, the cable was placed in a -40℃ environment for 1 million dynamic bends, with a bending radius of 6 times the cable's outer diameter and a bending frequency of 30 bends / min. After bending, the shielding attenuation value was tested again under the same test conditions. The shielding attenuation test frequency range was 1MHz-100MHz, and the shielding attenuation value at 100MHz was recorded. Shielding attenuation retention rate = shielding attenuation value after low-temperature bending / shielding attenuation value before low-temperature bending × 100%.

[0040] Table 1. Cable performance test data

[0041] Combining Example 1 and Comparative Examples 1-4, Comparative Example 1 did not add powdered nitrile rubber, polyether-type TPU, or maleic anhydride-grafted POE. It relied solely on PVC resin and a cold-resistant plasticizing system to improve low-temperature performance. After low-temperature impact, the sheath cracking rate reached 60%, and the dynamic bending life was only 1.82 million cycles, indicating that relying solely on the PVC matrix and plasticizer is insufficient to meet the requirements for frequent bending at low temperatures. Comparative Example 2 added powdered nitrile rubber but did not add polyether-type TPU or maleic anhydride-grafted POE. Its sheath cracking rate after low-temperature impact was reduced to... The dynamic bending life increased to 2.86 million cycles, but was still significantly lower than in Example 1. This indicates that while powdered nitrile rubber can improve the low-temperature hardening problem of PVC, its improvement on low-temperature rebound, abrasion resistance, and interfacial compatibility is limited when used alone. Comparative Example 3 did not contain dioctyl sebacate and dioctyl adipate, retaining only polyester plasticizers. Its sheath cracking rate after low-temperature impact was 20%, and its dynamic bending life was 3.94 million cycles. This indicates that the flexibility of the outer sheath at low temperatures was significantly reduced without small-molecule cold-resistant plasticizers. Comparative Example 4 will be implemented... In Example 1, after replacing the silane-modified nano-calcium carbonate with an equal amount of unmodified nano-calcium carbonate, the low-temperature impact sheath cracking rate increased from 0% to 20%, the dynamic bending life decreased from 5.35 million cycles to 4.18 million cycles, and the shielding attenuation retention rate decreased from 94.2% to 90.9%. This indicates that although unmodified nano-calcium carbonate can play a certain role in filling and reinforcing, its surface polarity is relatively high, resulting in poor compatibility with the composite organic system composed of PVC resin, powdered nitrile rubber, polyether-type TPU, and maleic anhydride-grafted POE, which easily leads to... Agglomeration occurs in the outer sheath system, forming stress concentration points and microcrack sources during low-temperature bending. In Example 1, through the synergistic effect of PVC resin, powdered nitrile rubber, polyether-type TPU, maleic anhydride-grafted POE, cold-resistant plasticizing system, silane-modified nano-calcium carbonate, compound lubricant, and composite shielding structure, the cable exhibits significant advantages in low-temperature impact, low-temperature dynamic bending, and signal transmission stability after low-temperature bending, meeting the requirements of frequent bending, dragging, and stable signal transmission in low-temperature environments.

[0042] Combining Examples 1-3, Examples 2 and 3 used higher contents of elastic toughening components and cold-resistant plasticizing components, respectively, and their dynamic bending lives reached 6.72 million and 6.48 million cycles, respectively, both significantly higher than that of Example 1. This indicates that increasing the amount of powdered nitrile rubber, polyether-type TPU, maleic anhydride-grafted POE, and cold-resistant plasticizing system can further improve the low-temperature flexibility and bending fatigue resistance of the outer sheath. However, in Example 3, the amount of plasticizer and elastomer was higher. Although the low-temperature resistance was better, the dynamic bending life was slightly lower than that of Example 2. This indicates that excessively high amounts of softening components may lead to a decrease in the dimensional stability and tear resistance of the sheath.

[0043] Combining Examples 2, 4, and 5, Example 4, using the silane-modified nano-calcium carbonate obtained in Example 2, exhibits the best overall performance. This indicates that when the silane coupling agent and PEG-400 are in an appropriate ratio, the surface coating of the nano-calcium carbonate is more uniform, resulting in better dispersion in the outer sheath composite system. It can synergistically form a multi-level buffer structure of "inorganic stress dispersion point - polar interface layer - low-temperature elastic phase" with the elastic toughening system, thereby significantly improving the low-temperature crack resistance, dynamic bending life, and shielding structure stability of the sheath. In Example 5, the dosage of silane coupling agent and PEG-400 is further increased, and its dynamic bending life is 7.01 million cycles, slightly lower than that of Example 4. This indicates that when the dosage of silane coupling agent is too high, silane may undergo a certain degree of self-condensation, leading to local agglomeration of nano-calcium carbonate, which is detrimental to the uniform dispersion of the filler in the outer sheath system.

[0044] Combining Examples 4, 6, and 7, Examples 6 and 7 used oxidized polyethylene wax and PE wax as lubricants separately, respectively, and their dynamic bending life and shielding attenuation retention rate were lower than those of Example 4. This indicates that when oxidized polyethylene wax and PE wax are used in combination, they can take into account both filler dispersion lubrication and extrusion external lubrication effects, which is beneficial to reducing surface defects and internal microcrack sources of the sheath, thereby improving the structural stability and signal transmission stability after low-temperature bending.

[0045] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A low-temperature resistant flexible cable, characterized in that: The cable includes a conductor, an insulation layer, a cabling unit, a shielding layer, and an outer sheath arranged sequentially. The outer sheath is made of the following components in parts by weight: 100 parts PVC resin, 12-25 parts powdered nitrile rubber, 5-15 parts polyether-type TPU, 6-18 parts maleic anhydride-grafted POE, 8-18 parts dioctyl sebacate, 6-15 parts dioctyl adipate, 5-15 parts polyester plasticizer, 3-8 parts epoxidized soybean oil, 4-12 parts silane-modified nano-calcium carbonate, 3-6 parts calcium-zinc composite stabilizer, 0.2-0.8 parts antioxidant, 0.8-3 parts matte black masterbatch, 0.5-2 parts lubricant, and 0.5-2 parts silicone masterbatch.

2. The low-temperature resistant flexible cable according to claim 1, characterized in that: The preparation method of the silane-modified nano-calcium carbonate includes the following steps: Take nano-calcium carbonate with a particle size of 40-100 nm and dry it at 100-120℃ for 2.5-3.5 h; separately take anhydrous ethanol, deionized water and glacial acetic acid, mix them, adjust the pH to 4.5, then add silane coupling agent and PEG-400, stir and hydrolyze at 28-32℃ to obtain silane hydrolysate; The dried nano-calcium carbonate was added to a high-speed mixer, the powder temperature was controlled at 85-95℃, and the mixture was stirred at a speed of 1200 r / min. The silane hydrolysate was atomized and sprayed into the high-speed mixer. After the spraying was completed, the mixing and stirring continued. Then the temperature was raised to 105℃ and the stirring continued. Subsequently, the resulting powder was vacuum dried, and after air jet pulverization and sieving, silane-modified nano-calcium carbonate was obtained.

3. The low-temperature resistant flexible cable according to claim 2, characterized in that: The weight ratio of the nano-calcium carbonate, silane coupling agent, and PEG-400 is 100:(2.0-2.4):(0.3-0.4).

4. The low-temperature resistant flexible cable according to claim 1, characterized in that: The antioxidant comprises a mixture of antioxidant 1010 and antioxidant 168.

5. A low-temperature resistant flexible cable according to claim 1, characterized in that: The lubricant comprises a mixture of oxidized polyethylene wax and PE wax.

6. A method for preparing a low-temperature resistant flexible cable as described in any one of claims 1-5, characterized in that: Includes the following steps: Preparation of outer sheath material: PVC resin, calcium-zinc composite stabilizer, epoxidized soybean oil, and antioxidant are added to a high-speed mixer and mixed at 300-500 r / min for 2-3 min; the speed is increased to 900-1200 r / min, and when the material temperature rises to 55-65℃, dioctyl sebacate, dioctyl adipate, and polyester plasticizer are added sequentially, and mixing continues to 95℃; then silane-modified nano calcium carbonate, powdered nitrile rubber, matte black masterbatch, and lubricant are added, and mixing continues to 105-110℃ before discharge and cooling. When the material temperature drops below 45℃, polyether-type TPU, maleic anhydride-grafted POE, and silicone masterbatch are added and mixed for 5-8 min to obtain a premix; the premix is ​​added to a twin-screw extruder for melt blending and granulation, and after extrusion and pelletizing, the outer sheath material is obtained; Conductor stranding: 26 fine copper wires with a diameter of 0.1 mm and 2 copper foil wires with a diameter of 0.23 mm are stranded to the left, with the stranding pitch controlled at 13 mm. The outer diameter of the conductor after stranding is 0.7 mm. Insulation extrusion: A colored PVC insulation layer is extruded over the conductor. The insulation extrusion process is used to produce yellow, blue, green and red insulated wire cores respectively. Cable forming and wrapping: The yellow, blue, green and red insulated wire cores are twisted into a cable in left-hand order, and cotton rope is added to the center for filling. The cable pitch is controlled at 20-23mm. Single-sided aluminum foil is wrapped around the outer layer with the metal side of the aluminum foil facing outward and the overlap rate is 20%. The outer diameter after wrapping is controlled at 3.5-3.7mm, and the cable unit is obtained by molding. Shielding layer assembly: A composite guide wire is set on the outside of the aluminum foil of the cabling unit, which is formed by combining 30 fine copper wires with a diameter of 0.1 mm and 3 copper foil wires with a diameter of 0.23 mm. The composite guide wire is in contact with the metal surface of the aluminum foil. The aluminum foil and the composite guide wire together form a shielding layer. The outer diameter after shielding is controlled to be 3.7-3.9 mm. Outer sheath extrusion: The outer sheath material is dried and extruded onto the outside of the shielding layer using a tube extrusion process to form the outer sheath; Post-processing: After the outer sheath is extruded, it is cooled and shaped in sections of cooling water tanks at 35-45℃ and 20-30℃, and then printed for inspection to obtain a low-temperature resistant flexible cable.

7. The method for preparing a low-temperature resistant flexible cable according to claim 6, characterized in that: In the insulation extrusion step, the thickness of the insulation layer is 0.3-0.5 mm.

8. The method for preparing a low-temperature resistant flexible cable according to claim 6, characterized in that: In the outer sheath extrusion step, the extrusion temperature is set sequentially to 138℃, 148℃, 158℃, 163℃, 165℃, 165℃ and 162℃, and the traction speed is 10-14m / min.

9. The method for preparing a low-temperature resistant flexible cable according to claim 8, characterized in that: In the outer sheath extrusion step, the thickness of the outer sheath is 0.8-1.2 mm.

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