Flame-retardant fire-resistant flexible cable for communication power supply and manufacturing method thereof

Abstract

The present application relates to a kind of communication power supply fire-retardant fire-resistant flexible cable and its manufacturing method.The present application includes the conductor arranged from inside to outside, PTFE wrapping layer, first ceramic plastic sheath, fire-resistant wrapping assembly, second ceramic plastic sheath and environment-friendly smoke layer;Fire-resistant wrapping assembly includes the inner layer glass fiber tape, mica tape and outer layer glass fiber tape of reverse wrapping;The smoke starting temperature of environment-friendly smoke layer is lower than the melting bonding temperature of PTFE wrapping layer, so that environment-friendly smoke layer generates the smoke of triggering fire alarm first, and PTFE wrapping layer forms the porous fusion block layer for bearing external impact and isolating the conductor in adjacent cable when reaching the melting bonding temperature.The present application can provide smoke alarm in the early stage of fire, maintain the insulation isolation between adjacent conductors in the sustained stage of fire, and reduce the black smoke and chlorine-containing corrosive gas generated by burning conventional PVC sheath.

Description

Technical Field

[0001] This invention relates to the field of communication power cable technology, and in particular to a flame-retardant and fire-resistant flexible cable for communication power supply and its manufacturing method. Background Technology

[0002] Flame-retardant and fire-resistant flexible cables for communication power supplies are typically laid in communication equipment rooms, data centers, equipment rooms, or outdoor communication facilities. In these locations, electrical equipment is concentrated, and the cables bear the responsibility of providing continuous power and signal protection. In the event of a fire, the cables not only need to limit the spread of flames but also need to maintain insulation between conductors for a certain period to prevent premature power outages due to short circuits.

[0003] However, existing communication power cables often use PVC as the insulation or sheath. PVC is prone to carbonization, embrittlement, and pulverization under sustained high temperatures or in combustion environments, producing thick black smoke and corrosive chlorine gases that severely irritate the eyes, throat, and respiratory system. Furthermore, when equipment parts or building components fall and impact an already brittle cable, the sheath and insulation may crack, causing adjacent cable cores to come into contact, resulting in short circuits, power outages, and other accidents. The thick black smoke and corrosive gases can also hinder the evacuation of trapped personnel, rescue operations, and subsequent equipment repairs. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the problems of existing communication power cables, such as the sheath easily becoming brittle and powdery in a fire, adjacent conductors easily short-circuiting after being hit by falling objects, the PVC material producing a large amount of black smoke and corrosive gas when burning, and the lack of active warning function of the cable body.

[0005] To solve the above-mentioned technical problems, the present invention provides a flame-retardant and fire-resistant flexible cable for communication power supply, comprising: conductor; The PTFE wrapping layer includes a PTFE wrapping tape wrapped around the outer periphery of the conductor. The PTFE wrapping layer maintains a flexible wrapping structure under normal cable operation and can undergo interlayer fusion bonding when the fusion bonding temperature is reached to form a porous fusion block layer. A first ceramic-plastic sheath is disposed on the outer periphery of the PTFE wrapping layer; A fire-resistant wrapping assembly is disposed on the outer periphery of the first ceramic-plastic sheath, comprising an inner layer of fiberglass tape, a mica tape, and an outer layer of fiberglass tape arranged radially outward in sequence; A second ceramic-plastic sheath is disposed on the outer periphery of the refractory wrapping assembly; An environmentally friendly smoke-generating layer is disposed on the outer periphery of the second ceramic-plastic sheath and includes a diatomaceous earth composite smoke-generating material; The smoke-generating initiation temperature of the environmentally friendly smoke-generating layer is lower than the melting and bonding temperature of the PTFE wrapping layer, causing the environmentally friendly smoke-generating layer to generate smoke that triggers a fire alarm first. When the PTFE wrapping layer reaches the melting and bonding temperature, it forms a porous fused block layer that can withstand external impacts and isolate conductors in adjacent cables. The first ceramic plastic sheath, the fire-resistant wrapping assembly, and the second ceramic plastic sheath are used to regulate the heat transfer rate to the PTFE wrapping layer and can prevent the molten and bonded PTFE from being blown away by gas (hot airflow from flames or high-temperature airflow) during combustion (or from flowing or falling off during melting and bonding).

[0006] In one embodiment of the present invention, the thickness of the PTFE wrapping layer is 0.5 to 0.8 times the outer diameter of the conductor; the total thickness of the PTFE wrapping layer is 0.7 to 2.6 mm.

[0007] In one embodiment of the present invention, the PTFE wrapping layer is formed by wrapping PTFE wrapping tape with a wrapping tension of 50-75N and an overlap rate of 30%-40%.

[0008] In one embodiment of the present invention, adjacent layers of the inner fiberglass tape, the mica tape, and the outer fiberglass tape adopt opposite wrapping directions.

[0009] In one embodiment of the present invention, both the first ceramic-plastic sheath and the second ceramic-plastic sheath are made of a low-smoke, halogen-free ceramic polymer material that can form a ceramicized shell when heated.

[0010] In one embodiment of the present invention, the diatomaceous earth composite smoke-generating material includes an extrudable polymer matrix, a porous diatomaceous earth carrier dispersed in the polymer matrix, and a fog-forming component loaded in the pores of the porous diatomaceous earth carrier. The thickness of the environmentally friendly smoke-generating layer is 0.3 to 0.8 mm, and the smoke-generating initiation temperature is 260°C.

[0011] The present invention also provides a method for manufacturing the aforementioned flame-retardant and fire-resistant flexible cable for communication power supply, comprising: On a wire bundling machine, multiple annealed soft copper wires are bundled into strands using a predetermined pitch and in either a left- or right-hand direction. On a tube stranding machine or a cage stranding machine, multiple strands are stranded into a conductor using a predetermined pitch and in either a left- or right-hand direction. A PTFE wrapping tape is tightly wrapped around the outer periphery of the conductor to form a PTFE wrapping layer; A first ceramic-plastic sheath is extruded around the outer periphery of the PTFE wrapping layer; The inner layer of fiberglass tape, mica tape and outer layer of fiberglass tape are wrapped around the outer periphery of the first ceramic plastic sheath in sequence to form a fire-resistant wrapping assembly, wherein adjacent layers adopt opposite wrapping directions; A second ceramic-plastic sheath is extruded around the outer periphery of the refractory wrapping assembly; Diatomaceous earth composite smoke-generating material is continuously extruded onto the outer periphery of the second ceramic-plastic sheath to form an environmentally friendly smoke-generating layer.

[0012] In one embodiment of the present invention, when tightly wrapping PTFE wrapping tape around the outer periphery of the conductor, the wrapping tension is set to 50-75N, the overlap rate is set to 30%-40%, and the total thickness of the PTFE wrapping layer is controlled to be 0.5-0.8 times the outer diameter of the conductor and 0.7-2.6mm.

[0013] In one embodiment of the present invention, when a refractory wrapping assembly is formed on the outer periphery of the first ceramic plastic sheath, the tension of the inner layer fiberglass tape and the outer layer fiberglass tape is controlled at 10-15N, the tension of the mica tape is controlled at 8-12N, and the overlap rate of the inner layer fiberglass tape, the mica tape and the outer layer fiberglass tape is 15%-25%.

[0014] In one embodiment of the present invention, when continuously extruding diatomite composite smoke-generating material around the outer periphery of the second ceramic-plastic sheath, the mist-generating component is first loaded onto a dried diatomite porous carrier, and then the diatomite porous carrier loaded with the mist-generating component is mixed with an extrudable polymer matrix to form a diatomite composite smoke-generating material, and the thickness of the environmentally friendly smoke-generating layer is controlled to be 0.3-0.8 mm.

[0015] The technical solution of the present invention has the following advantages compared with the prior art: The flame-retardant and fire-resistant flexible cable for communication power supply provided by this invention utilizes the specific radial arrangement of the environmentally friendly smoke-generating layer, the second ceramic-plastic sheath, the fire-resistant wrapping assembly, the first ceramic-plastic sheath, and the PTFE wrapping layer, as well as the thermal response temperature difference of different materials, to form a phased protective structure that functions sequentially as the fire temperature rises. During the normal operation of the cable, the overall structure maintains flexibility to meet the bending, laying, and winding requirements of the communication power supply flexible cable. In the early stages of a fire, the environmentally friendly smoke-generating layer, located on the outermost side and with a lower smoke initiation temperature, first generates smoke that can be detected by smoke detectors. As the fire continues to develop, the first ceramic-plastic sheath, the fire-resistant wrapping assembly, and the second ceramic-plastic sheath provide heat insulation, fire resistance, and structural restraint. When heat continues to transfer inward and the PTFE wrapping layer reaches its melting and bonding temperature, adjacent PTFE wrapping strips undergo interlayer melting and bonding to form an integral porous fused block layer. Therefore, the cable is able to achieve a coordinated thermal response of triggering alarm, heat insulation and fire resistance, and fusion isolation. Through the low-temperature smoke response of the environmentally friendly smoke-generating layer, the heat insulation constraint of the double-layer ceramic plastic sheath and the reverse wrapping fire-resistant components, the high-temperature melting and bonding of the PTFE wrapping layer, and the coordination between the thermal response temperature and radial position of each layer, a protection mechanism is formed from early fire warning to protection during the continuous fire stage.

[0016] In this invention, the outer fire-resistant structure provides constraint for the formation of a stable fusion layer of PTFE on the inner side, enabling the cable to simultaneously maintain flexibility under normal conditions, provide active warning capability in the early stages of a fire, provide fire-resistant insulation capability during the sustained fire phase, and provide conductor isolation capability after external mechanical impact. It can also reduce the black smoke and chlorine-containing corrosive gases generated by the combustion of traditional PVC cables, making it more suitable for the continuous power supply and safety protection needs of communication power systems in complex fire environments.

[0017] The present invention sets the environmentally friendly smoke-generating layer on the outer periphery of the second ceramic plastic sheath, and makes the smoke-generating initiation temperature of the environmentally friendly smoke-generating layer lower than the melting and bonding temperature of the PTFE wrapping layer, so that the environmentally friendly smoke-generating layer can generate smoke before the PTFE wrapping layer undergoes significant melting and bonding.

[0018] The environmentally friendly smoke-generating layer of this invention uses a diatomaceous earth composite smoke-generating material. The mist-forming components are loaded through the pores of a porous diatomaceous earth carrier, and the diatomaceous earth porous carrier loaded with the mist-forming components is dispersed in an extrudable polymer matrix. The porous diatomaceous earth carrier can adsorb and retain the mist-forming components, reducing their migration and surface seepage during cable storage at room temperature, winding, and long-term use. The polymer matrix allows the composite material to form a stable outer sheath using existing continuous cable extrusion processes. Therefore, this invention does not directly coat easily migratable smoke-generating components onto the cable surface, but rather forms a stable composite smoke-generating system through porous carrier loading and polymer matrix fixation, improving the storage stability of the mist-forming components in non-fire conditions while maintaining continuous extrusion processing capabilities. Controlling the thickness of the environmentally friendly smoke-generating layer to 0.3–0.8 mm also achieves a reasonable balance between the mist-forming component content per unit length, alarm smoke generation capability, cable outer diameter, and finished product flexibility.

[0019] The PTFE wrapping layer in this invention has different structural forms under normal and fire conditions. Under normal use, the PTFE wrapping layer consists of multiple layers of PTFE wrapping tape, retaining the interface between adjacent wrapping tapes. Instead of pre-fusion-bonding the entire PTFE wrapping layer at high temperatures during cable manufacturing, this allows the conductor's outer insulation structure to maintain good bending flexibility. As the fire continues to heat up, when the PTFE wrapping layer reaches its melting and bonding temperature, adjacent PTFE wrapping tapes fuse together in the overlapping area, gradually transforming the flexible wrapping tape into a monolithic, porous, fused block layer. This structure realizes the transformation of the PTFE wrapping layer from a normal-temperature flexible insulation structure to a high-temperature monolithic isolation structure, allowing the same material to adapt to both normal laying and fire protection conditions.

[0020] This invention sets the thickness of the PTFE wrapping layer to 0.5–0.8 times the outer diameter of the conductor, and controls its total thickness to 0.7–2.6 mm. Simultaneously, the wrapping tension of the PTFE wrapping tape is controlled to 50–75 N, and the overlap rate to 30%–40%. Appropriate wrapping tension allows the PTFE wrapping tape to adhere to the conductor and maintain interlayer contact, while avoiding excessively loose wrapping that creates large gaps or excessively tight wrapping that leads to excessive stretching of the PTFE tape and reduced flexibility of the finished product. The 30%–40% overlap rate allows adjacent PTFE wrapping tapes to form a continuous overlapping area, providing sufficient contact area for fusion bonding between adjacent layers in a fire condition. Combined with the thickness of the PTFE wrapping layer, this ensures that the structure after heat fusion has certain radial dimensions and structural integrity. Therefore, by controlling the combination of thickness, wrapping tension, and overlap rate, it is beneficial to balance flexibility and insulation performance under normal conditions with the ability to form an integral fused structure under fire conditions.

[0021] This invention provides a first ceramic-plastic sheath on the outside of the PTFE wrapping layer, and a second ceramic-plastic sheath on the outside of the fire-resistant wrapping assembly, positioning the fire-resistant wrapping assembly between the two ceramic-plastic sheaths. The first and second ceramic-plastic sheaths maintain the flexibility of the polymer material at room temperature, gradually forming a ceramicized shell under the high temperature of a fire, thus creating a two-tiered high-temperature structural support around the PTFE wrapping layer. On one hand, the two ceramic-plastic sheaths and the fire-resistant wrapping assembly together increase the path of heat transfer from the outside of the cable to the PTFE wrapping layer, preventing the PTFE wrapping layer from experiencing a sudden and drastic temperature rise due to external flames, which is beneficial for forming a thermal response process suitable for the gradual melting and bonding of the PTFE wrapping tape. On the other hand, the ceramicized shell and the fire-resistant wrapping assembly can radially constrain the PTFE during softening and melting, reducing the possibility of the molten PTFE being blown away by flames, hot air current disturbances, or changes in cable posture, allowing the molten PTFE to bond together around the original conductor and remain as a porous fused block layer.

[0022] The fire-resistant wrapping assembly of this invention employs an inner layer of fiberglass tape, a mica tape, and an outer layer of fiberglass tape arranged radially, with the mica tape positioned between two layers of fiberglass tape. The mica tape provides primary high-temperature insulation and fire-resistant barrier properties. The inner and outer fiberglass tapes reinforce and constrain the mica tape from both the inner and outer sides, respectively, thereby reducing the risk of cracking and loosening of the mica tape during cable bending, wrapping, sheath extrusion, and after exposure to heat during a fire. Adjacent layers use opposite wrapping directions, preventing the overlap gaps between the inner, mica, and outer fiberglass tapes from continuously corresponding in the same helical direction. This also reduces the accumulation of wrapping stress in the same direction across the layers, thus improving the overall stability of the fire-resistant wrapping assembly under bending and high-temperature conditions.

[0023] The manufacturing method provided by this invention can continuously manufacture each functional layer in the following sequence: conductor stranding, PTFE wrapping, extrusion of the first ceramic-plastic sheath, reverse layered wrapping of the fire-resistant wrapping assembly, extrusion of the second ceramic-plastic sheath, and continuous extrusion of the environmentally friendly smoke-generating layer. Specifically, in the PTFE wrapping stage, high-temperature sintering treatment that causes premature overall melting of the PTFE layer is avoided, thus preserving the flexibility of the finished cable at room temperature and the structural conditions for further interlayer melting and bonding under fire conditions. By controlling the PTFE wrapping tension, overlap ratio, and total thickness, the melting conditions under fire conditions are made more consistent. By first loading the mist-forming component onto a dried diatomaceous earth porous carrier, and then mixing and extruding it with the polymer matrix, the loss of the mist-forming component during processing and normal use is reduced. This manufacturing method is integrated into existing cable wrapping and extrusion processes and has good adaptability to continuous processing. Attached Figure Description

[0024] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0025] Figure 1 This is a schematic diagram of the cross-sectional structure of the flame-retardant and fire-resistant flexible cable for communication power supply of the present invention.

[0026] Figure 2 This is a flowchart illustrating the manufacturing method of the flame-retardant and fire-resistant flexible cable for communication power supply according to the present invention.

[0027] Explanation of reference numerals on the accompanying drawings: 1. Conductor; 2. PTFE wrapping layer; 3. First ceramic-plastic sheath; 4. Fire-resistant wrapping assembly; 41. Inner fiberglass tape; 42. Mica tape; 43. Outer fiberglass tape; 5. Second ceramic-plastic sheath; 6. Environmentally friendly smoke-generating layer. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0029] In this invention, when directions (up, down, left, right, front, and back) are described, it is only for the convenience of describing the technical solution of this invention, and does not indicate or imply that the technical features referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0030] In this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," "exceeding," etc., are understood to exclude the stated number; "above," "below," "within," etc., are understood to include the stated number. In the description of this invention, the terms "first" and "second" are used only to distinguish technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0031] In this invention, unless otherwise explicitly defined, the terms "setting," "installing," and "connecting" should be interpreted broadly. For example, they can refer to a direct connection or an indirect connection through an intermediate medium; a fixed connection, a detachable connection, or an integrally formed connection; a mechanical connection, an electrical connection, or a connection capable of mutual communication; or the internal connection of two components or the interaction between two components. Those skilled in the art can reasonably determine the specific meaning of the above terms in this invention based on the specific content of the technical solution.

[0032] Example 1 Reference Figure 1As shown, this embodiment provides a flame-retardant and fire-resistant flexible cable for communication power supply and its manufacturing method. The flexible cable has a multi-layer coaxial sheath structure, which includes, from the inside out, a conductor 1, a PTFE (polytetrafluoroethylene) wrapping layer 2, a first ceramic plastic sheath 3, a fire-resistant wrapping assembly 4, a second ceramic plastic sheath 5, and an environmentally friendly smoke-generating layer 6.

[0033] Specifically, conductor 1 is formed by stranding multiple annealed soft copper wires. Annealed soft copper wires have good conductivity and bending properties. The cross-sectional area, single wire diameter, and stranding pitch of conductor 1 are determined according to the rated current and flexibility requirements of the communication power supply.

[0034] Specifically, the PTFE wrapping layer 2 is tightly wrapped around the outer periphery of the conductor 1. PTFE material has high heat resistance, dielectric properties, and arc resistance. The PTFE wrapping layer 2 ensures the insulation strength between the conductor 1 and the external structure under normal cable operation. The thickness of the PTFE wrapping layer 2 is selected according to the outer diameter of the conductor 1. In this embodiment, it is preferably 0.5 to 0.8 times the outer diameter of the conductor 1, and the thickness is 0.7 to 2.6 mm.

[0035] Specifically, the PTFE wrapping layer 2 is formed by wrapping with PTFE wrapping tape. During wrapping, the tension is controlled at 50–75 N, and the overlap rate is controlled at 30%–40%. The overlap rate is the ratio of the overlap width of two adjacent turns of PTFE wrapping tape projected onto the cable surface to the width of the PTFE wrapping tape. A wrapping tension of 50–75 N allows each wrapping tape to adhere to the conductor 1. When the wrapping tension is less than 50 N, the tape layers are prone to loosening and forming large gaps; when the wrapping tension is greater than 75 N, the PTFE wrapping tape will be overstretched, the conductor 1 will deform, or the flexibility of the finished product will be reduced. An overlap rate of 30%–40% increases the fusion bonding area between adjacent tape layers when heated in a fire. This is because when the overlap rate is less than 30%, the effective bonding area between adjacent tape layers after heating is small; when the overlap rate is greater than 40%, the local thickness increases and the amount of material used increases.

[0036] It should be noted that, unlike the PTFE insulation layer that is pre-sintered at high temperatures during general production, the PTFE wrapping layer 2 in this embodiment retains the interface between the PTFE wrapping tapes after production, giving the cable better flexibility. When the fire continues and the temperature of the PTFE wrapping layer 2 reaches its melting and bonding temperature, the molten PTFE inside is not easily blown away by the airflow under the constraint of the external multi-layer structure. The multi-layer PTFE wrapping film softens and flows when heated, the film interface disappears, and the molecular chains can completely melt and diffuse fully, forming a dense integral insulation layer without interfaces between different wrapping layers. The insulation performance is optimal. The multi-layer film is fused into one piece, and after cooling, it forms a solid block (porous fused block layer) with high hardness. It is not easy to crack when falling objects hit the cable at the fire scene. Therefore, after being wrapped, the conductor 1 can maintain the electrical insulation between the conductors 1 after the outer sheath is burned or after being hit by falling objects.

[0037] Specifically, the first ceramic-plastic sheath 3 is extruded around the outer periphery of the PTFE wrapping layer 2. The first ceramic-plastic sheath 3 remains flexible at room temperature and gradually forms a ceramicized shell with mechanical support capabilities under fire temperatures. This shell restricts radial deformation of the PTFE wrapping layer 2 and delays direct heat entry into the conductor 1 region. The thickness of the first ceramic-plastic sheath 3 can be determined based on the cable's outer diameter and the sheath thickness requirements of the communication power cable.

[0038] Specifically, the refractory wrapping assembly 4 includes an inner layer of fiberglass tape 41, a mica tape 42, and an outer layer of fiberglass tape 43. The inner layer of fiberglass tape 41 is tightly wrapped around the outer periphery of the first ceramic-plastic sheath 3, the mica tape 42 is wrapped around the outer periphery of the inner layer of fiberglass tape 41, and the outer layer of fiberglass tape 43 is wrapped around the outer periphery of the mica tape 42. Adjacent layers use opposite wrapping directions to reduce gaps between layers and improve the wrapping stability of the refractory wrapping assembly 4.

[0039] It should be noted that the inner fiberglass tape 41 has high temperature resistance and tensile strength, which can restrain the mica tape 42 and maintain the integrity of the fire-resistant wrapping assembly 4; the mica tape 42 has fire-resistant insulation properties, which is used to block flames and high-temperature gases from entering the inner layer radially. The inner fiberglass tape 41, mica tape 42 and outer fiberglass tape 43 are all tightly wrapped using an overlapping method, and the overlap rate of each layer can be determined according to the tape width and the outer diameter of the finished product.

[0040] It should be noted that the inner fiberglass tape 41 and the outer fiberglass tape 43 can be made of alkali-free fiberglass tape, fiberglass cloth tape, or tape with similar heat resistance and reinforcing properties; the mica tape 42 can be made of phlogopite mica tape 42, synthetic mica tape 42, or calcined mica tape 42.

[0041] Specifically, the second ceramic-plastic sheath 5 is extruded around the outer periphery of the refractory wrapping assembly 4. The second ceramic-plastic sheath 5 is used to protect the refractory wrapping assembly 4 under normal conditions and to form an outer ceramicized shell during a fire. By placing the first ceramic-plastic sheath 3 and the second ceramic-plastic sheath 5 on the inner and outer sides of the refractory wrapping assembly 4, respectively, the heated areas of the refractory wrapping assembly 4 can be constrained.

[0042] It should be noted that the first ceramic-plastic sheath 3 and the second ceramic-plastic sheath 5 can be made of the same ceramicized polymer material, or different ceramicized polymer materials can be used according to the requirements of the softness, shelling temperature and mechanical strength of the inner and outer layers.

[0043] Specifically, the environmentally friendly smoke-generating layer 6 is continuously extruded onto the outer periphery of the second ceramic-plastic sheath 5. In this embodiment, the thickness of the environmentally friendly smoke-generating layer 6 is preferably 0.3–0.8 mm. This is because when the thickness is too small, the amount of mist-forming components that can be released per unit length of cable is relatively small, which may prevent the formation of smoke that reaches the detection threshold within a predetermined time; when the thickness is too large, the total amount of mist-forming components increases, which can easily have adverse effects on the cable's outer diameter, bending performance, anti-sticking properties during winding, and room temperature storage stability.

[0044] In some embodiments, the diatomaceous earth composite smoke-generating material includes an extrudable polymer matrix, a porous diatomaceous earth carrier, and an environmentally friendly mist-generating component loaded within the pores of the porous diatomaceous earth carrier. The polymer matrix enables the environmentally friendly smoke-generating layer 6 to be continuously formed using a cable extrusion device and to maintain a stable coating relationship with the second ceramic-plastic sheath 5; the porous diatomaceous earth carrier adsorbs the mist-generating component, reducing its migration and exudation to the surface at room temperature; the mist-generating component volatilizes or undergoes a controllable thermal response at a predetermined temperature to form white tracer smoke.

[0045] The polymer matrix of the environmentally friendly smoke-generating layer 6 can be a low-smoke, halogen-free material that is compatible with the second ceramic-plastic sheath 5 and suitable for continuous extrusion; the diatomaceous earth porous carrier can be screened, dried, surface modified, or coupled to improve its dispersibility in the polymer matrix. The types and loading of the mist-forming components can be determined according to the target smoke-generating temperature, smoke generation per unit length, and environmental protection requirements for flue gas.

[0046] It should be noted that, to balance environmental friendliness and alarm triggering reliability, the fogging components are preferably low-toxicity fogging materials that do not contain halogens, heavy metals, or highly corrosive components. The generated smoke is used to increase the concentration of smoke particles or the light-blocking rate in the environment, thereby being detected by smoke detectors in the alarm system within the computer room. The smoke detectors can then send alarm signals to the fire control panel, which will activate audible and visual alarms, smoke extraction, power outages, or other fire-fighting equipment according to preset linkage logic.

[0047] It should be noted that when the cable is used in an open outdoor area, the white smoke generated by the environmentally friendly smoke-generating layer 6 can be used to improve the visibility of a fire; when the cable is used in an indoor computer room, the smoke generated by the environmentally friendly smoke-generating layer 6 can be used to trigger smoke detectors. Both applications fall under the alarm function.

[0048] Furthermore, the term "high environmental protection" in this embodiment refers to a reduction in the generation of chlorine-containing corrosive gases and black smoke compared to cables of the same specification with PVC sheaths, rather than indicating that it is absolutely non-toxic under fire conditions.

[0049] In this embodiment, the diatomaceous earth composite smoking material includes silane-modified 3000-mesh diatomaceous earth, 58# fully refined paraffin wax, food-grade corn starch, a compatibilizer, and an antioxidant. The compatibilizer is at least one of EVA wax and polyethylene wax, used to improve the compatibility between the components, reduce material delamination, and improve the adhesion between the composite smoking material and the matrix material. The antioxidant is used to inhibit oxidation of the composite smoking material under normal temperature storage conditions, reducing oil separation caused by oxidation.

[0050] The preferred loading of the smoking component in the diatomaceous earth is 30%–50% of the diatomaceous earth mass, balancing the storage capacity of the smoking component, material stability, and thermal release performance. Diatomaceous earth possesses a hierarchical pore structure ranging from nanometer to micrometer scale, with micropores having a diameter of 20 nm–50 nm and macropores having a diameter of 100–300 nm, resulting in an overall porosity of 80%–90%. This hierarchical pore structure adsorbs and loads smoking components such as paraffin, allowing the smoking components to be more uniformly dispersed within the diatomaceous earth and gradually released during heating, thereby improving the loading stability and smoke uniformity of the composite smoking material. The thickness of the environmentally friendly smoke-generating layer 6 is 0.3 mm–0.8 mm, and the smoke initiation temperature is 260℃. In the event of a fire, when the external temperature of the cable rises to the smoke initiation temperature, the outermost environmentally friendly smoke-generating layer 6 will be the first to produce smoke. The smoke initiation temperature is 260℃. Because the environmentally friendly smoke-generating layer 6 is located on the outermost side, it can generate smoke before the heat is fully transferred to the PTFE wrapping layer 2, thus providing an initial fire warning.

[0051] As the fire continues and heat is further transferred inward, the first ceramic-plastic sheath 3, the fire-resistant wrapping assembly 4, and the second ceramic-plastic sheath 5 slow down heat transfer and form a radial temperature gradient. When the temperature of the PTFE wrapping layer 2 reaches the melt-bonding temperature, adjacent PTFE wrapping tapes melt-bond. The melt-bonding temperature is a controlled temperature range below its significant thermal decomposition temperature, which can be determined, for example, by approximately 360–380°C depending on the PTFE material used.

[0052] Therefore, the cable forms a phased process of alarm first, then protection: the environmentally friendly smoke-generating layer 6 first generates smoke for alarm purposes, and then the PTFE wrapping layer 2 forms an integral fused insulation layer to maintain isolation between adjacent conductors 1. The first ceramic-plastic sheath 3, the fire-resistant wrapping assembly 4, and the second ceramic-plastic sheath 5 cannot completely block heat, but they can regulate the heat transfer rate, allowing the PTFE wrapping layer 2 to obtain sufficient heat for melting and bonding, while reducing the risk of its prolonged excessive thermal decomposition.

[0053] In this embodiment, the flame-retardant and fire-resistant flexible cable for communication power supply was tested for fire resistance using testing equipment. The PTFE wrapping layer 2 is made of polytetrafluoroethylene film from Fuchengwei Company, grade FA151. When the cable is placed in a continuous combustion environment of about 750°C for 90 minutes, the PTFE wrapping layer 2 inside the cable fuses and forms a relatively continuous protective layer. Before being heated, the PTFE wrapping tape is in a wrapped shape; after being heated, adjacent tape layers bond together and form an integral structure.

[0054] In this embodiment, the porous fused block layer formed after the PTFE wrapping layer 2 is subjected to a high-voltage spark test using a 10kV high-voltage spark tester. No breakdown occurred during the test, indicating that the formed porous fused block layer still has good continuity and insulation integrity, and can continue to form insulation isolation for the internal conductor after the external structure of the cable is damaged by high temperature.

[0055] In this embodiment, the formed porous fused block layer was subjected to a compressive strength test using a professional compressive strength tester. Under a pressure of 700 N for 2 minutes, no significant cracking or failure occurred. After the test, visual inspection revealed no cracking in the protective layer, but the porous fused block layer showed signs of flattening. The original thickness was 5.93 mm, which decreased to 5.16 mm after flattening, a change rate of approximately 13%. Furthermore, based on the detection images and corresponding change curves collected during the compressive strength test, after 2 minutes of continuous application of 700 N pressure, the detection curves did not show any abrupt changes or significant abnormal fluctuations; the change rate of relevant characteristic quantities was only approximately 13%, indicating that the porous fused block layer did not experience significant structural instability or damage during continuous compression, and its compressive strength exhibits good stability.

[0056] In this embodiment, the porous fused block layer after the pressure test was subjected to a 10kV high-voltage spark test to verify the integrity of the porous fused block layer. The test showed that the porous fused block layer did not crack and remained intact, indicating that the porous fused block layer was sufficient to withstand pressure.

[0057] Example 2 Reference Figure 2 As shown, this embodiment provides a method for manufacturing the flame-retardant and fire-resistant flexible cable for communication power supply described in Embodiment 1, including the following steps: S1. Preparation of conductor 1. On a wire bundling machine, multiple annealed soft copper wires are bundled into strands using a predetermined pitch and in either a left-hand or right-hand direction.

[0058] S2. Perform the stranding process. On a tube stranding machine or cage stranding machine, multiple strands are stranded into conductor 1 using a predetermined pitch and in either a left-hand or right-hand direction.

[0059] S3. Forming the PTFE wrapping layer 2. The PTFE wrapping tape is loaded into the wrapping equipment, allowing conductor 1 to advance along the production line, and the PTFE wrapping tape is tightly wrapped around the outer circumference of conductor 1 in a spiral manner. The width, number of layers, and wrapping angle of the PTFE wrapping tape are selected according to the outer diameter of conductor 1. The total thickness is controlled to be 0.5–0.8 times the outer diameter of conductor 1 and is selected to be 0.7–2.6 mm. The wrapping tension is controlled to be 50–75 N, and the overlap rate is controlled to be 30%–40%.

[0060] In step S3, the high-temperature sintering treatment that pre-melts all the layers into a whole is not performed on the PTFE wrapping layer 2, so that the completed PTFE wrapping layer 2 retains the multi-layer wrapping tape structure and bending flexibility.

[0061] S4. Conduct semi-finished product inspection. This includes inspection of outer diameter, surface quality, etc.

[0062] S5, Form the first ceramic-plastic sheath 3.

[0063] The ceramicized polymer sheath material is added to the cable extrusion equipment, and the first ceramic-plastic sheath 3 is continuously extruded around the outer periphery of the PTFE wrapping layer 2. The extrusion thickness is controlled according to the YD / T 1173 industry standard, and the material is cooled and shaped using a cooling water tank. The extrusion temperature is set according to the processing window of the selected ceramicized polymer material to avoid the PTFE wrapping layer 2 from melting together during the production stage due to extrusion heat.

[0064] S6. Forming the refractory wrapping assembly 4. First, tightly wrap the inner layer of fiberglass tape 41 around the outer periphery of the first ceramic-plastic sheath 3. Then, wrap the mica tape 42 in the opposite direction to the inner layer of fiberglass tape 41. Finally, wrap the outer layer of fiberglass tape 43 in the opposite direction to the mica tape 42. By wrapping adjacent layers in opposite directions, the overlap gaps of each layer are staggered, reducing the accumulation of wrapping stress in the same direction. When forming the refractory wrapping assembly 4 around the outer periphery of the first ceramic-plastic sheath 3, the tension of the inner layer of fiberglass tape 41 and the outer layer of fiberglass tape 43 are controlled at 10-15N, the tension of the mica tape 42 is controlled at 8-12N, and the overlap rate of the inner layer of fiberglass tape 41, the mica tape 42, and the outer layer of fiberglass tape 43 is 15%-25%.

[0065] S7. Forming the second ceramic-plastic sheath 5. A ceramicized polymer sheath material is continuously extruded onto the outer periphery of the refractory wrapping assembly 4. The extrusion thickness is controlled according to the YD / T 1173 industry standard to form the second ceramic-plastic sheath 5. During the extrusion process, the second ceramic-plastic sheath 5 provides radial constraint to the refractory wrapping assembly 4, ensuring that each layer remains tightly bonded.

[0066] S8. Prepare and extrude an environmentally friendly smoke-generating layer 6. Dry the diatomaceous earth porous carrier to reduce the influence of moisture in the pores on the loading of the mist-generating components and polymer processing; impregnate or mix the environmentally friendly mist-generating components into the pores of the diatomaceous earth porous carrier; then mix the diatomaceous earth porous carrier loaded with the mist-generating components with an extrudable polymer matrix and granulate to obtain a diatomaceous earth composite smoke-generating material.

[0067] The diatomaceous earth composite smoke-generating material is added to the outer extrusion equipment and continuously extruded around the outer periphery of the second ceramic-plastic sheath 5 to form an environmentally friendly smoke-generating layer 6. The thickness of the environmentally friendly smoke-generating layer 6 is controlled to be 0.3–0.8 mm. The extrusion temperature should be lower than the significant volatilization temperature of the mist-generating component, and the diatomaceous earth composite smoke-generating material should have sufficient melt strength to avoid loss of the mist-generating component during extrusion and cooling.

[0068] S9. Produce finished products into trays.

[0069] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A flame-retardant and fire-resistant flexible cable for communication power supply, characterized in that, include: Conductor (1); The PTFE wrapping layer (2) includes a PTFE wrapping tape wrapped around the outer periphery of the conductor (1). The PTFE wrapping layer (2) maintains a flexible wrapping structure under normal cable operation and can undergo interlayer fusion bonding when the fusion bonding temperature is reached to form a porous fusion block layer. The first ceramic plastic sheath (3) is disposed on the outer periphery of the PTFE wrapping layer (2); The fire-resistant wrapping assembly (4) is disposed on the outer periphery of the first ceramic plastic sheath (3) and includes an inner layer of fiberglass tape (41), a mica tape (42) and an outer layer of fiberglass tape (43) arranged radially outward. The second ceramic-plastic sheath (5) is disposed on the outer periphery of the refractory wrapping assembly (4); An environmentally friendly smoke-generating layer (6) is disposed on the outer periphery of the second ceramic plastic sheath (5) and includes a diatomaceous earth composite smoke-generating material; The smoke-generating initiation temperature of the environmentally friendly smoke-generating layer (6) is lower than the melting and bonding temperature of the PTFE wrapping layer (2), so that the environmentally friendly smoke-generating layer (6) generates smoke that triggers a fire alarm first. When the PTFE wrapping layer (2) reaches the melting and bonding temperature, it forms a porous fused block layer for withstanding external impacts and isolating the conductors (1) in adjacent cables. The first ceramic plastic sheath (3), the fire-resistant wrapping assembly (4), and the second ceramic plastic sheath (5) are used to regulate the rate of heat transfer to the PTFE wrapping layer (2) and can prevent the molten and bonded PTFE from being blown away by gas during combustion.

2. The flame-retardant and fire-resistant flexible cable for communication power supply according to claim 1, characterized in that, The thickness of the PTFE wrapping layer (2) is 0.5 to 0.8 times the outer diameter of the conductor (1), and the total thickness of the PTFE wrapping layer (2) is 0.7 to 2.6 mm.

3. The flame-retardant and fire-resistant flexible cable for communication power supply according to claim 1, characterized in that, The PTFE wrapping layer (2) is formed by wrapping PTFE wrapping tape with a wrapping tension of 50-75N and an overlap rate of 30%-40%.

4. The flame-retardant and fire-resistant flexible cable for communication power supply according to claim 1, characterized in that, The inner fiberglass tape (41), the mica tape (42), and the outer fiberglass tape (43) have adjacent layers with opposite wrapping directions.

5. The flame-retardant and fire-resistant flexible cable for communication power supply according to claim 1, characterized in that, Both the first ceramic plastic sheath (3) and the second ceramic plastic sheath (5) are made of low-smoke halogen-free ceramic polymer material that can form a ceramic shell when heated.

6. The flame-retardant and fire-resistant flexible cable for communication power supply according to claim 1, characterized in that, The diatomite composite smoke-generating material includes an extrudable polymer matrix, a porous diatomite carrier dispersed in the polymer matrix, and a fog-generating component loaded in the pores of the porous diatomite carrier. The thickness of the environmentally friendly smoke-generating layer (6) is 0.3 to 0.8 mm, and the smoke-generating initiation temperature is 260°C.

7. A method for manufacturing a flame-retardant and fire-resistant flexible cable for communication power supply according to any one of claims 1-6, characterized in that, include: On a wire bundling machine, multiple annealed soft copper wires are bundled into strands using a predetermined pitch and in either the left or right direction. On a tube stranding machine or a cage stranding machine, multiple strands are stranded into a conductor using a predetermined pitch and in either the left or right direction (1). A PTFE wrapping tape is tightly wrapped around the outer periphery of the conductor (1) to form a PTFE wrapping layer (2). A first ceramic plastic sheath (3) is extruded around the outer periphery of the PTFE wrapping layer (2); A fire-resistant wrapping assembly (4) is formed on the outer periphery of the first ceramic plastic sheath (3), including wrapping an inner layer of fiberglass tape (41), a mica tape (42) and an outer layer of fiberglass tape (43) around the outer periphery of the first ceramic plastic sheath (3) in sequence to form a fire-resistant wrapping assembly (4), wherein two adjacent layers adopt opposite wrapping directions; A second ceramic plastic sheath (5) is extruded around the outer periphery of the refractory wrapping assembly (4); Diatomaceous earth composite smoke-generating material is continuously extruded around the outer periphery of the second ceramic plastic sheath (5) to form an environmentally friendly smoke-generating layer (6).

8. The method for manufacturing a flame-retardant and fire-resistant flexible cable for communication power supply according to claim 7, characterized in that, When tightly wrapping PTFE wrapping tape around the outer periphery of the conductor (1), the wrapping tension is set to 50-75N, the overlap rate is set to 30%-40%, and the total thickness of the PTFE wrapping layer (2) is controlled to be 0.5-0.8 times the outer diameter of the conductor (1) and 0.7-2.6mm.

9. The method for manufacturing a flame-retardant and fire-resistant flexible cable for communication power supply according to claim 7, characterized in that, When the refractory wrapping assembly (4) is formed on the outer periphery of the first ceramic plastic sheath (3), the tension of the inner layer fiberglass tape (41) and the outer layer fiberglass tape (43) is controlled at 10-15N, the tension of the mica tape (42) is controlled at 8-12N, and the overlap rate of the inner layer fiberglass tape (41), the mica tape (42) and the outer layer fiberglass tape (43) is 15%-25%.

10. The method for manufacturing a flame-retardant and fire-resistant flexible cable for communication power supply according to claim 7, characterized in that, When continuously extruding diatomite composite smoke-generating material around the outer periphery of the second ceramic plastic sheath (5), the mist-generating component is first loaded onto a dried diatomite porous carrier, and then the diatomite porous carrier loaded with the mist-generating component is mixed with an extrudable polymer matrix to form a diatomite composite smoke-generating material, and the thickness of the environmentally friendly smoke-generating layer (6) is controlled to be 0.3-0.8 mm.

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